阅读说明：本技术 具有热转移图像的泡沫不透明元件 (foamed opaque element with thermally transferred image ) 是由 M.奈尔 D.M.赫里克 于 2018-04-30 设计创作，主要内容包括：可以制备泡沫不透明元件,以在多孔基材的相对外表面和内表面任一者上具有热着色剂图像。该内表面具有作为干燥不透明层布置于其上的干燥泡沫组合物,该干燥泡沫组合物包含：(a)0.1-40重量%的多孔颗粒；(b)至少10重量%的至少部分固化的粘合剂材料；(c)至少0.2重量%的包含表面活性剂的一种或更多种添加剂；(d)小于5重量%的水；和(e)至少0.002重量%的不同于所有的一种或更多种(c)添加剂的不透明着色剂,该不透明着色剂吸收预定电磁辐射。热着色剂图像由来自热供体元件的可升华着色剂的热着色剂转移得到。(the foamed opacifying element can be prepared to have a thermal colorant image on either of the opposing outer and inner surfaces of the porous substrate. The inner surface has disposed thereon as a dry opaque layer a dry foam composition comprising: (a)0.1-40 wt% of porous particles; (b) at least 10 wt% of an at least partially cured binder material; (c) at least 0.2 wt% of one or more additives comprising a surfactant; (d) less than 5 wt% water; and (e) at least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives, the opacifying colorant absorbing the predetermined electromagnetic radiation. The thermal colorant image is derived from thermal colorant transfer of a sublimable colorant from a thermal donor element.)

1. A method of providing a foamed opaque element comprising a thermal colorant image, comprising:

Providing a porous substrate having opposing outer and inner surfaces, said porous substrate further comprising a dry foam composition disposed as a dry opaque layer on said inner surface of said porous substrate,

Wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having a mode particle size of at least 2 μm and up to and including 50 μm and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase having a glass transition temperature of greater than 80 ℃ and being contained at a concentration of 20 wt% in ethyl acetate at 100s at 25 ℃^-1a polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) At least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) Less than 5 wt% water; and

(e) At least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives that absorbs the predetermined electromagnetic radiation,

All amounts being based on the total weight of the dry foam composition,

Wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, an

Providing a thermal colorant image on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer by thermal colorant transfer from a thermal donor element comprising a colorant donor layer comprising one or more thermal colorants.

2. the method of claim 1, wherein the thermal colorant image is a multi-color thermal colorant image provided by a plurality of thermal colorant transfer operations using a plurality of thermal donor elements.

3. the method of claim 1, wherein the thermal colorant image is a multicolor thermal colorant image provided by a multicolor mirror image on a single thermal donor element.

4. The method of any one of claims 1 to 3, wherein at least 0.01 g/m²And up to and including 5 g/m²To provide the thermal colorant image.

5. the method of any one of claims 1 to 4, wherein the one or more thermal colorants are one or more sublimable dyes.

6. The method of any one of claims 1 to 5, comprising:

Providing the thermal colorant image by overlaying the colorant donor layer of the thermal donor element with the dry opaque layer, an

The one or more thermal colorants are imagewise transferred from the colorant donor layer to the dry opaque layer by applying heat to the thermal donor element, with or without pressure, on the side opposite the colorant donor layer.

7. the method of any one of claims 1 to 5, comprising:

Providing the thermal colorant image by superposing the colorant donor layer of the thermal donor element with the opposing outer surface of the porous substrate, and

The one or more thermal colorants are imagewise transferred from the colorant donor layer to the opposing outer surface by applying heat to the thermal donor element on a side opposite the colorant donor layer, with or without pressure.

8. The method of any one of claims 1 to 7, comprising:

providing the thermal colorant image by: imagewise transferring the one or more thermal colorants from the colorant donor layer onto the opposing outer surface of the porous substrate by thermal printing using a resistive head or a laser.

9. the method of any one of claims 1 and 3 to 8, wherein the thermal donor element comprises blocks of two or more different thermal dye blocks and blocks comprising a transparent protective overcoat composition.

10. The method of any one of claims 1 and 3 to 9, wherein the thermal donor element comprises an inkjet printed mirror image of the thermal colorant image.

11. The method of any one of claims 1 to 10, wherein the porous substrate comprises polyester and the one or more thermal colorants are one or more thermally sublimable dyes.

12. The method of any one of claims 1 to 11, further comprising:

Providing a metallic image by heat transfer to any of the opposing outer surfaces, the dry opaque layer, or the thermal colorant image.

13. The method of any one of claims 1 to 12, further comprising:

Providing a dry non-opaque layer on the dry opaque layer, the dry non-opaque layer comprising a tinting colorant, a flame retardant, an antimicrobial agent, an antiblock agent, or a flocking agent.

14. The method of any one of claims 1 to 13, wherein the opacifying colorant is carbon black present in an amount of at least 0.002% by weight and up to and including 1% by weight, based on the total weight of the dry foam composition.

15. The method of any one of claims 1 to 14, wherein the dry foam composition has at least 98% solids.

16. the process of any one of claims 1 to 15, wherein the continuous polymer phase comprises at least 70 weight percent and up to and including 100 weight percent of one or more polymers derived from one or more of cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate, based on the total polymer weight in the continuous polymer phase.

17. The method of any one of claims 1 to 16, wherein the porous particles are present in an amount of at least 0.5 wt% and up to and including 10 wt%, based on the total weight of the dry foam composition.

18. The method of any one of claims 1 to 17, wherein the at least partially cured binder material is present in an amount of at least 20 wt% and up to and including 60 wt%, and has a glass transition temperature of less than 25 ℃.

19. The method of any one of claims 1 to 18, wherein the at least partially cured binder material has a glass transition temperature of less than 0 ℃.

20. The method of any one of claims 1 to 19, wherein the one or more (c) additives comprise an antimicrobial agent comprising silver metal, a silver-containing compound, copper metal, a copper-containing compound, or a mixture of any of these.

21. The method of any one of claims 1 to 20, wherein the one or more thermal colorants comprise sublimable cyan, yellow, magenta, or black dyes, or a combination thereof.

22. The method of any one of claims 1 to 21, wherein the porous substrate comprises a porous woven web, a porous polymeric membrane, a porous cellulosic material, a porous ceramic material, or a porous glass material.

23. The method of any one of claims 1 to 22, wherein the porous substrate comprises a polyester.

24. the method of any one of claims 1 to 23, wherein the dry opaque layer is the only layer disposed on the porous substrate.

25. The method of any one of claims 1 to 24, further comprising disposing a dry non-opaque layer on the dry opaque layer.

26. the method of claim 25, wherein the dry non-opaque layer comprises a tinting colorant, a flame retardant, an antimicrobial agent, an antiblock agent, or a flocking agent.

27. the method of any one of claims 1 to 26, wherein the dry foam composition comprises at least 0.5 wt% and up to and including 10 wt% of the porous particles having a mode particle size of at least 3 μ ι η and up to and including 30 μ ι η, based on the total weight of the dry foam composition.

28. The method of any one of claims 1 to 27, wherein the one or more (c) additives further comprise metal flakes present within the porous particles.

29. The method of any one of claims 1 to 28, wherein the surfactant of the one or more (c) additives is a foaming agent, and the one or more (c) additives further comprise a foam stabilizer.

30. the process of any one of claims 1 to 29, wherein the one or more (c) additives further comprise a tinting colorant in an amount of at least 0.0001 weight% and up to and including 3 weight%, based on the total weight of the dry foam composition.

31. The process of any one of claims 1 to 30, wherein the one or more (c) additives further comprise an optical brightener in an amount of at least 0.001 wt% and up to and including 0.4 wt%, based on the total weight of the dry foam composition.

32. The method of any one of claims 1 to 31, further comprising providing a transparent protective layer over the thermal colorant image.

33. A foamed opacifying element obtained from the method of any one of claims 1 to 32, comprising a thermal colorant image, the foamed opacifying element further comprising a porous substrate having opposing outer and inner surfaces, the inner surface having a dry foam composition disposed thereon as a dry opacifying layer,

wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having a mode particle size of at least 2 μm and up to and including 50 μm and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase having a glass transition temperature of greater than 80 ℃ and being contained at a concentration of 20 wt% in ethyl acetate at 100s at 25 ℃^-1A polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) At least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) Less than 5 wt% water; and

(e) at least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives that absorbs the predetermined electromagnetic radiation,

All amounts being based on the total weight of the dry foam composition,

Wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, and

Wherein the thermal colorant image is disposed on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer.

34. The foamed opacifying element of claim 33, wherein the dry opacifying layer exhibits a light-blocking value of at least 5.

Technical Field

The present invention relates to a method of providing a foamed opacifying element useful as a light-blocking (opacifying) article, which also has a colorant image provided by a thermal transfer process. Foamed opaque elements have a dry opaque layer from a foamable aqueous composition that includes unique porous particles mixed with other necessary components so that foaming, application to a porous substrate, drying and densification of the composition can be easily achieved.

Background

Drapes (draperies) are designed primarily for style and appearance, and are typically made from various colored fabrics that are printed or in some other way carry a design or image. Digital printing is replacing the traditional methods in the textile industry. The main drivers are cost efficiency, ability to personalize printing, and flexibility. Traditional screen printing is being replaced by digital textile printing schemes like thermal transfer or sublimation printing for shorter production runs and personalized printing requiring multiple colors and detailed images. Thermal transfer or heat transfer is a process for imparting a desired color or color pattern or image to synthetic fabrics such as polyester, nylon, and acrylics. Thermal transfer printing uses thermally responsive inks containing sublimable colorants that sublime or evaporate under the influence of heat onto the surface of the fabric, penetrate the fibers and become entrained therein or attached to the textile fibers. Thermal transfer methods and materials are quite old and are described in numerous publications, such as U.S. Pat. Nos. 3,363,557 (Blake), 3,952,131 (Sideman), 4,139,343 (Steiner), 6,036,808 (Shaw-Klein et al), 8,628,185 (Hale et al), 9,315,682 (Delys et al), 4,117,699 (Renaut), 4,097,230(Sandhu), 4,576,610 (Donenfeld), 5,668,081 (Simpson et al) and 7,153,626 (Foster et al).

According to such imaging techniques, a color pattern (discontinuity or image) to be imparted to a textile substrate, such as a woven, nonwoven or knitted material, is pre-printed with an ink containing a sublimable colorant as a print or image on a substrate (typically a sheet of paper or nonwoven material) referred to as a transfer sheet or transfer donor element. The inks used to prepare the printed images contain colorants that are selected to sublime at temperatures that do not compromise the integrity of the fabric or textile substrate. The ink may be applied to an inert transfer donor support (conventionally paper) by a number of printing methods known in the art including gravure, flexographic, lithographic, rotary screen, electrophotographic and ink jet printing. Contacting the preprinted transfer donor element with the fabric to be printed under controlled time, temperature and pressure conditions such that the colorant of the image sublimes and is transferred from the transfer donor element to the fabric substrate, which substrate should have the properties of: it will receive and hold the transferred ink to provide a permanent print or image thereon. Since the colorant becomes part of the material structure, the image on the fabric is vivid, resistant to fading or deterioration after multiple washes, and exhibits good rub-off resistance. In addition, the textile substrate should be resilient to the heat and pressure required to transfer an image due to the volatilization or sublimation of the respective ink condensed on and absorbed by at least the outer surface layers of the individual fibers of the textile substrate. This effect can be easily obtained on many fabrics made from synthetic fibers, especially polyester fibers and blends of polyester and natural fibers.

For example, U.S. patent 4,139,343 (mentioned above) discloses transfer sheets for heat-transfer polyester textiles that are yellow-tinted, inks that can be used to prepare such transfer sheets, improved methods of heat-transferring polyester textiles, and printed or dyed fabrics produced thereby.

The art has recognized the difficulty of transferring images to fabrics made from naturally occurring or synthetic fibers, particularly fabrics comprising cotton, as described, for example, in U.S. patent 4,576,610 (mentioned above), wherein sublimable compositions are formulated with polyester binder resins, wherein the polymers have significant amounts of free carboxyl groups, to significantly improve the depth, uniformity and fastness of color imparted to cotton and other naturally occurring fibrous materials by sublimation dyeing techniques.

Drapes made from fabric and printed as described above to produce the desired visual effect are generally ineffective at preventing a significant amount of light from penetrating into the room from an external source, which produces a corresponding undesirable level of illumination without the need for light. To completely block unwanted light, drapes are usually composed of two separate elements: decorative or printed face fabric, and a separate shade material (or liner) attached to the decorative face fabric by sewing or other means. The shade material or liner is typically turned toward the window or other light source, and the decorative face fabric is hung in front of the window or other light source.

"opacifying" or light-blocking materials generally refer to articles that are substantially impermeable to light, such as visible or UV radiation. When a shading material is used to cover a window or other opening through which light can pass, the shading material is designed to completely block all external light from entering the room through the window or opening.

hotels and homes require light screening materials to ensure a desirable sleeping environment, to protect the interior from ultraviolet light, and to provide privacy. Residential use of shade materials is also desirable for those living in densely populated urban or suburban areas where the amount of light penetrating into the window at night may be significant due to sources such as street lights, light from adjacent buildings, and vehicle headlights. Hospitals may also use such materials to improve patient privacy and comfort, particularly where multiple patients share the same area.

The cost of manufacturing light-blocking drapes (lined with shade material) is higher than single textile or unlined drapes due to the increased expense of manufacturing the shade liner material and the increased labor of attaching the shade liner material to the face fabric. Additionally, drapery manufacturers should keep sufficient inventory of shade liner material on hand. Us patent 5,741,582(Leaderman et al) suggests the possibility of embossing, dyeing or decorating a shade structure of material fabric on both sides of the drapery lining rather than on the exposed foam, thereby acting as a self-lining drapery fabric.

the shade material or liner is a multi-layer structure having a minimum of three separate coated layers. For example, U.S. patent 4,677,016 (Ferziger et al) describes a light blocking article comprising a fabric backed by a first coating of white acrylic foam, followed by a second coating of acrylic foam having an opaque color, and finally a third coating of white acrylic foam. U.S. patent application publication 2002/0122949 (Richards) describes light blocking articles that are layered structures composed of two layers of fabric, two layers of foam, and a metallized plastic sheet.

These multilayer opacifying liners are sufficiently opaque to light, but are not suitable for thermal transfer. They tend to outgas significantly, producing unacceptable levels of harmful fumes at the temperatures required to sublime and transfer the sublimable colorants. High temperatures may also cause the multilayer light screening material to suffer delamination or loss of interlayer adhesion. Poor image quality due to incomplete and inconsistent transfer of the sublimable ink from the donor element to the multilayer opacifying liner is commonly reported. Such problems can arise in multilayer shade liners known in the art, even those comprising polyester or comprising another synthetic fabric including blends, due to the continuous layer of interlayer carbon black which can absorb heat and thereby act as a heat sink during the intended sublimation process. These unwanted effects can also occur in metallized shade curtains.

Accordingly, there is a need to provide sunscreen articles containing suitable colorant images or prints achieved using thermal transfer chemistry and methods that avoid these problems.

Summary of The Invention

The present invention provides a method for providing a foamed opaque element comprising a thermal colorant image, comprising:

Providing a porous substrate having opposing outer and inner surfaces, the porous substrate further comprising a dry foam composition disposed as a dry opaque layer on the inner surface of the porous substrate,

Wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having a mode particle size of at least 2 μ ι η and up to and including 50 μ ι η and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase having a glass transition temperature of greater than 80 ℃ and being comprised at 25 ℃ at a concentration of 20 wt% in ethyl acetate at 100s^-1A polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) At least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) Less than 5 wt% water; and

(e) At least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs the predetermined electromagnetic radiation,

All amounts are based on the total weight of the dry foam composition,

Wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, an

Providing a thermal colorant image on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer by thermal colorant transfer from a thermal donor element comprising a colorant donor layer comprising one or more thermal colorants.

The present invention also provides a foamed opacifying element comprising a thermal colorant image, the foamed opacifying element further comprising a porous substrate having opposing outer and inner surfaces, the inner surface having a dry foam composition disposed thereon as a dry opacifying layer,

Wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having a mode particle size of at least 2 μ ι η and up to and including 50 μ ι η and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase having a glass transition temperature of greater than 80 ℃ and being comprised at 25 ℃ at a concentration of 20 wt% in ethyl acetate at 100s^-1A polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) At least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) less than 5 wt% water; and

(e) At least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs the predetermined electromagnetic radiation,

all amounts are based on the total weight of the dry foam composition,

Wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, and

Wherein the thermal colorant image is disposed on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer.

The foamed opacifying elements and the process for their preparation according to the present invention offer many advantages. The present invention overcomes the disadvantages of the articles known in the art by providing a separate, self-lining drape (foam opaque element) that is impermeable to light and is durable enough to withstand the temperatures required for thermal transfer operations. The foamed opacifying element of the invention is a stand-alone, self-lined, light-blocking drape having a porous substrate, a single dry opacifying layer derived from a dry foam composition disposed on one supporting side (or inner surface) of the porous substrate, and a heat-transferred colorant image disposed on the opposite outer surface of the porous substrate or dry opacifying layer. In most embodiments, the foamed opaque element consists only of these specific features. Thus, either or both of the opposing outer and inner surfaces (or opposing sides) of the foamed opacifying element may have an applied decorative pattern or image provided using a thermal transfer method.

The foamed opaque element provided according to the present invention avoids the use of a carbon black layer that can act as a heat sink during the thermal colorant transfer process. In addition, the present invention reduces the outflow of harmful fumes common during known transfer colorant transfer processes.

The foamed opacifying element contains a very small amount of opacifying colorant in the dried opacifying composition, which is not damaged by temperatures greater than 100 ℃ that may be used during the thermal colorant transfer process or during the manufacturing drying operation. Foamed opaque elements (or light blocking articles), such as freestanding, self-lined light shades, exhibit desirable opacity, improved flexibility, "feel" and drape. The manufacturing operation (process) can easily be performed in a continuous manner, for example in a roll-to-roll operation.

It is very important to understand that the foamed opacifying element according to the invention has a simpler construction than the light-blocking articles described in the prior art. For example, such articles include a single dry opaque layer that is both opaque and resistant to delamination at high temperatures and pressures. The present invention avoids thick and multi-layer constructions while providing the significant advantage of having very little opacifying colorant (e.g., up to and including 1 weight percent total solids). Because the opacifying colorant may be contained within the porous particles and so little opacifying colorant is used, the foamed opacifying element remains light in color and, when it is damaged or pierced, the escape of opacifying colorant and its effect on other materials is minimized. In addition, low levels of opacifying colorant enable more efficient thermal colorant transfer.

In some embodiments, the foamed opacifying element made according to the present invention comprises a single dry opacifying layer that also has any or all of antimicrobial, opacifying, and flame retardant properties, as well as desirable light-blocking properties.

Detailed Description

The following discussion is directed to various embodiments of the invention, and although some embodiments may be desirable for particular uses, the disclosed embodiments should not be interpreted, or otherwise regarded, as limiting the scope of the invention as claimed below. In addition, one skilled in the art will appreciate that the following disclosure has broader application than that explicitly described and discussed for any of the embodiments.

Definition of

as used herein to define the various components of the foamed aqueous composition, the foamable aqueous composition, the dry foam composition, the thermal colorant transfer composition, or the material used to prepare the porous particles, the singular forms "a, an" and "the" are intended to include one or more components (i.e., including the plural referents) unless otherwise indicated.

Each term not explicitly defined in the present application should be understood to have the meaning commonly accepted by those skilled in the art. A term definition should be taken from a standard dictionary if its construction makes it meaningless or substantially meaningless in its context.

The use of numerical values in the various ranges specified herein is considered approximate, as if the word "about" preceded both the minimum and maximum values within the stated ranges, unless expressly stated otherwise. In this manner, minor variations above and below the stated ranges can be used to achieve substantially the same results as values within the stated ranges. In addition, the disclosure of these ranges is intended as a continuous range including every value between the minimum and maximum values.

Unless otherwise indicated, the terms "foamed opacifying element," "light-blocking article," and "light-blocking drape" are intended to refer to the same material.

Unless otherwise indicated, the term "opposing outer surface" refers to a flat surface of a porous substrate (defined below) that typically does not have a dry opaque layer disposed thereon. Such an opposing outer surface may be the surface of the foamed opaque element that generally faces the viewer.

Unless otherwise indicated, the term "inner surface" refers to a flat surface of a porous substrate (defined below) on which the dry opaque layer is disposed for blocking incident light from various sources (e.g., sunlight, street lights, and any external light source) that is to be blocked from passing through the dry opaque layer off the opposite outer surface of the foamed opaque element.

As used herein, unless otherwise indicated, the terms "porous particles" and "porous particles" refer to porous organic polymeric materials that can be used in foamable aqueous compositions, foamed aqueous compositions, dry foamed compositions, and foamed opacifying elements. The porous particles generally comprise a solid continuous polymeric phase having an outer particle surface and discrete pores dispersed within the continuous polymeric phase. The continuous polymeric phase may also be chemically crosslinked or elastomeric in nature, or both.

the continuous polymer phase of the porous particles typically has the same composition throughout the solid phase. That is, the continuous polymer phase is generally homogeneous in the composition including any additives (e.g., colorants) that may be incorporated therein. In addition, if mixtures of polymers are used in the continuous polymer phase, typically those mixtures are also uniformly dispersed throughout.

The term "isolated from each other" as used in this disclosure means that different (dissimilar) pores of the same or different sizes are separated from each other by some continuous polymer phase, and such pores are not typically interconnected.

The terms "first discrete pores" and "second discrete pores" refer to distinct sets of isolated pores that may be used in the porous particles of the present invention. These first and second discrete holes refer to distinct sets of holes. Each distinct set of pores includes a plurality of pores isolated from each other, and the pores of each set of pores are isolated from all other pores of the other sets of pores in the porous particle. Each group of holes may have the same mode average size, or both groups may have the same mode average size. The word "discrete" is also used to define the different droplets of the first and second aqueous phases when they are suspended in the oil (solvent) phase used to make the porous particles.

Porous particles may include "micro", "meso" and "macro" discrete pores, which according to the International Union of Pure and Applied Chemistry (International Union of Pure and Applied Chemistry) are the recommended classes for discrete pore sizes of less than 2 nm, from 2 nm to 50 nm and greater than 50 nm, respectively. Thus, while the porous particles may include closed discrete pores of all sizes and shapes that provide a suitable volume in each discrete pore (i.e., discrete pores entirely within the continuous polymer phase), large discrete pores are particularly useful. Although open macropores may be present on the surface of the porous particles, such open pores are undesirable and may only be present by chance. The size, formulation and manufacturing conditions of the porous particles are the primary controlling factors for the discrete pore size. Typically, however, the discrete pores independently have an average size of at least 100 nm and up to and including 7,000 nm, or more likely at least 200 nm and up to and including 2,000 nm. Regardless of the size of the discrete pores, they are generally randomly distributed throughout the continuous polymer phase. If desired, the discrete pores may be predominately grouped into a portion of the porous particle (e.g., a "core" or "shell").

In some embodiments, where there are different sets of discrete pores, the first set of discrete pores is predominately closer to the outer particle surface than the second set of discrete pores. For example, a set of smaller discrete holes may be predominantly near the outer particle surface as compared to a set of larger discrete holes. The term "predominantly" as used herein means that a greater number fraction of pores of one size is found in the "shell" region closer to the surface of the porous particle than would be desirable based on the total number fraction of two or more types (sizes) of pores present in the porous particle.

The porous particles used in the present invention typically have a porosity of at least 20 volume% and up to and including 70 volume%, or possibly at least 40 volume% and up to and including 65 volume%, or more typically at least 45 volume% and up to and including 60 volume%, all based on the total volume of the porous particle. The porosity can be measured using mercury intrusion techniques, where mercury is crushed at high pressure to close the pores and the volume of the (irreversibly) crushed pores is used to measure the porosity (pore volume). A high degree of separation under pressure was observed between the interstitial filling of mercury between the particles and pore crushing. The gap filling is a function of both the particle size distribution and particle packing in the penetrometer, while the cell crush signal is due to the compressibility of the particles as a function of the wall thickness and the change in its modulus.

"opacity" is a measured parameter of a foamed opaque element that characterizes the degree of transmission of electromagnetic radiation, such as visible light. Greater opacity indicates more effective blocking (shadowing) of predetermined radiation (as described below). In the present invention, the "opacity" of a foamed, opacifying element may be measured in terms of a Light Blocking Value (LBV) (as described below in connection with the examples), which determines the degree of impinging radiation or light blocked by the foamed, opacifying element. The higher the LBV, the greater the light blocking ability exhibited by the foamed opacifying element. The articles of the present invention typically exhibit an LBV of at least 4.

The glass transition temperature of the organic polymer used to prepare the continuous polymer phase can be measured using Differential Scanning Calorimetry (DSC) using known procedures. For many commercially available organic polymers, the glass transition temperature is known from the supplier.

the polymer viscosity (in centipoise) of the continuous polymer phase can be measured in a couette (coquette) Anton par MCR 301 stress rheometer using a stable shear scan at a polymer concentration of 20 wt.% in ethyl acetate at 25 ℃. From the obtained graph of viscosity versus shear rate, 100s was calculated^-1Shear rate of (b).

CIELAB L, a, and b values have known definitions according to CIE1976 color space or later known color space versions and are calculated assuming a standard D65 illuminant. X, Y and the Y tristimulus value of the Z tristimulus values may be used as a measure of the light reflectance or "brightness" of the dried opaque layer.

Unless otherwise indicated, the terms "thermal transfer process" and "heat transfer process" are intended to refer to the same sublimation or vapor phase process of printing or dyeing textile fabrics, wherein the textile is colored with a thermal colorant that undergoes sublimation at a temperature below that which compromises the physical integrity of the textile.

use of

The foamable aqueous composition and the foamed aqueous composition can be used to prepare foamed opacifying elements, which in turn can be used as radiation (light) blocking materials, in the form of: shade liners, roller shades, privacy curtains, banners and curtains for airplanes, hospitals, homes; a label; a projection screen; textile fabrics and packaging materials. The foamed opaque elements may also exhibit improved sound and thermal insulation properties, and may have suitable images provided by a thermal colorant transfer process as described below for viewing on one or both sides. The term "shade liner" is intended to include, but is not limited to, draperies, shades for all purposes, draperies, room dividers, privacy curtains, and cubicle curtains for various environments and structures.

Foamable aqueous compositions

The foamable aqueous composition designed for use in the present invention may be suitably aerated to provide a foamed aqueous composition to prepare a foamed opacifying element according to the present invention. In many embodiments, the foamable aqueous composition has the following five essential components, which are the only components needed to obtain the light blocking properties and advantages described above: (a) porous particles as described below; (b) binder materials, also described below; (c) one or more additives as described below comprising at least one surfactant; (d) water; and (e) an opacifying colorant of all compounds other than component (c), which opacifying colorant absorbs "predetermined electromagnetic radiation" (typically UV to near IR, for example absorbs radiation of all wavelengths from 350 nm to 800 nm or 350 nm to and including 700 nm). Optional (optional) components that may be included are also described below.

the foamable aqueous composition typically has at least 35% and up to and including 70% solids, or more particularly at least 40% and up to and including 60% solids.

Porous particles:

The porous particles containing discrete pores (or cells) used in the present invention are used to dry the opaque layer and they are typically prepared as described below using one or more water-in-oil emulsions in combination with an aqueous suspension method, for example in an evaporative finite coalescence (ELC) process. Details regarding the preparation of porous particles are provided in, for example, U.S. patents 8,110,628 (Nair et al), 8,703,834 (Nair), 7,754,409 (Nair et al), 7,887,984 (Nair et al), 8,329,783 (Nair et al), and 8,252,414 (Putnam et al). The porous particles are typically polymeric and organic in nature (i.e., the continuous polymeric phase is polymeric and organic in nature), and non-porous particles (having a porosity of less than 5%) are excluded. As mentioned below, the inorganic particles may be present on the outer surface.

The porous particles consist of a continuous polymer phase derived from one or more organic polymers selected such that the continuous polymer phase has a glass transition temperature (T) of greater than 80 ℃ or more typically at least 100 ℃ and up to and including 180 ℃ or more likely at least 110 ℃ and up to and including 170 ℃, as determined using differential scanning calorimetry_g). Has a T of more than 200 DEG C_gIs generally less useful in the continuous polymer phase.

in addition, the continuous polymer phase comprises one or more polymers, as measured at 25 ℃, at a concentration of 20 wt% in ethyl acetate, at 100s^-1Each having a viscosity of at least 80 centipoise (0.080 mPa s) and up to and including 500 centipoise (0.5 mPa s). This feature is important to optimize the preparation of the porous particles used in the practice of the present invention so that the porous particles prepared have a narrow particle size distribution and high porosity.

For example, the continuous polymeric phase may comprise one or more polymers having the properties mentioned above, wherein typically at least 70 weight percent and up to and including 100 weight percent, based on the total weight of polymers in the continuous polymeric phase, is comprised of one or more cellulose polymers (cellulose polymers) including, but not limited to, those derived from one or more of cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate. Polymers derived solely from cellulose acetate butyrate are particularly useful. Mixtures of these cellulosic polymers can also be used if desired, and mixtures comprising at least 80% by weight of the total amount of cellulosic polymer (or all polymers in the continuous polymer phase) of a polymer derived from cellulose acetate butyrate are particularly useful mixtures.

Typically, the porous particles used in the present invention have a mode particle size equal to or less than 50 μm, or at least 2 μm and up to and including 50 μm, or typically at least 3 μm and up to and including 30 μm or even up to and including 40 μm. The most useful porous particles have a mode particle size of at least 3 μm and up to and including 20 μm. The mode particle size represents the most frequently occurring diameter for spherical particles and the most frequently occurring maximum diameter for non-spherical particles in the particle size distribution histogram.

Pore stabilizing materials (e.g., hydrocolloids) may be present within at least a partial volume of discrete pores distributed throughout the continuous polymer phase, which are described in the above-referenced patents. In some embodiments, the same pore stabilizing material is incorporated into substantially all of the discrete pores throughout the entire porous particle. In many embodiments, the pore stabilizing hydrocolloid is selected from the group consisting of carboxymethylcellulose (CMC), gelatin, proteins or protein derivatives, polyvinyl alcohol and its derivatives, hydrophilic synthetic polymers, and water soluble microgels.

in some embodiments, it may be desirable to provide additional stability of one or more discrete pores in the porous particles during their formation by having one or more amphiphilic block copolymers disposed at the interface of the one or more discrete pores and the continuous polymeric phase. Such materials are "low HLB," which means that they have an HLB (hydrophilic-lipophilic balance) value of 6 or less, or even 5 or less, as calculated using known science. Details of these amphiphilic polymers and their use in making porous particles are provided in U.S. patent 9,029,431 (Nair et al).

Particularly useful amphiphilic block copolymers that can be used in such embodiments comprise polyethylene oxide and polycaprolactone, which can be represented as PEO-b-PCL. Amphiphilic block copolymers, graft copolymers, and random graft copolymers containing similar components are also useful.

Such amphiphilic block copolymers may typically be present in the porous particles in an amount of at least 1 weight% and up to and including 99.5 weight%, or at least 2 weight% and up to and including 50 weight%, based on the total dry weight of the porous particles.

the porous particles used in the present invention may be spherical or non-spherical depending on the desired use. In the process for preparing porous particles, additives (shape control agents) may be incorporated into the first or second aqueous phase or the oil (organic) phase to alter the shape, aspect ratio or morphology of the porous particles. The shape control agent may be added before or after the formation of the water-in-oil-in-water emulsion. In either case, the interface of the oil phase and the second aqueous phase is altered prior to removal of the organic solvent, which results in a reduction in the sphericity of the porous particles. The porous particles used in the present invention may also comprise a surface stabilizer (e.g., colloidal silica) on the outer surface of each porous particle in an amount of at least 0.1 weight percent based on the total dry weight of the porous particles.

The average size of the discrete pores (or individually isolated and closed voids or compartments) is described above.

The porous particles may be provided as a powder or as an aqueous suspension comprising water or water and a water-miscible organic solvent, such as an alcohol. Such powders and aqueous suspensions may also include surfactants or suspending agents to keep the porous particles suspended in the aqueous medium or to rewet them in the aqueous medium. Surfactants useful for this purpose are, for example, C for polyethylene oxide₁₂-C₁₄Secondary alcohol derivatives as TERGITOL15-S-7 (Dow Chemical Corporation) are commercially available. Other compositional features are described in the incorporated description of the method for making the porous particles.

The porous particles are generally present in the foamable aqueous composition in an amount of at least 0.05 wt.% and up to and including 15 wt.%, or typically at least 0.5 wt.% and up to and including 10 wt.%, based on the total weight of the foamable aqueous composition (including water present), particularly when the porous particles have a mode size of at least 3 μm and up to and including 30 μm.

It is known in the art that typical white inorganic pigments (e.g., titanium dioxide) block electromagnetic radiation by light scattering due to the difference in refractive index between the inorganic pigment particles, which is affected by the pigment particle size, and the surrounding environment. In addition, only these fillable volumes (0.635 of random close packing of monodisperse spheres) are present before interstitial cavities are formed between the packed pigment particles.

The opacity of the opaque layer is enhanced by interstitial voids formed when the Particle Volume Concentration (PVC), typically pigment particles (e.g. titanium dioxide), is above a critical level. For example, the size of interstitial voids between pigment particles is smaller than the pigment particles themselves and decreases as the polydispersity of such pigment particles increases. Since the pigment particle size is optimized for maximum light scattering when dispersed in a polymer matrix above the critical PVC, the interstitial voids created by the pigment particles will be too small to simultaneously optimize the scattered light. Congestion occurs when the spacing between the pigment particles is reduced to the point where light scattering becomes dependent on the concentration of the pigment particles, and the efficiency of scattering by the pigment particles decreases as the pigment loading increases. This is known as "dependent scattering", which is the phenomenon whereby the effective scattering diameter or scattering area of the pigment particle becomes effectively larger than its actual diameter. These scattering regions overlap as the concentration of scattering pigment particles increases, which reduces the scattering efficiency and leads to a congestion effect. Small and large pigment particle size extenders have been used to create greater spacing between scattering pigment particles and to reduce overlap of scattering regions to create greater scattering efficiency and opacity.

advantageously, for the porous particles used in the present invention, the spacing between the light scattering discrete pores within the porous particles is controlled during the process of forming them and is not subject to subsequent formulation effects, such as dependent scattering effects.

An optimal dry opaque layer designed according to the present invention comprises: porous particles containing a small amount of an opacifying colorant, as described below, to enhance the light-blocking ability (particularly the ability to block transmitted light) of the porous particles; a binder material to hold the porous particles in place; and surfactants and other additives optionally including one or more tinting colorants (tinting colorants) that may be in other porous particles or dispersed within the dry opaque layer. The foamed aqueous composition used to prepare the dry opaque layer comprises cells surrounding porous particles.

upon drying the foamed aqueous composition, the large mismatch in refractive index between the discrete pores of the porous particles and the dry cells in the dry opaque layer and the polymer walls (continuous polymer phase) causes incident electromagnetic radiation passing through the dry opaque layer to be scattered by the various interfaces and discrete pores. The backscattered electromagnetic radiation may be scattered again and returned in the direction of the incident electromagnetic radiation, thereby reducing attenuation and contributing to the opacity strength and brightness or light reflectivity of the dried opaque layer. The opacity of the dried opaque layer is increased if a small amount of an opaque colorant that absorbs electromagnetic radiation is present in the porous particles of the dried opaque layer, for example in the discrete pores of the porous particles or in the continuous polymer phase. This is because multiple scattering of the electromagnetic radiation in the dry opaque layer increases the path length of the electromagnetic radiation through the dry opaque layer, thereby increasing the chance that the electromagnetic radiation will encounter the opaque colorant in the dry opaque layer and be blocked or absorbed by it.

The individual dry opaque layers present in embodiments of the present invention comprise porous particles and a relatively low amount of an opaque colorant (e.g., carbon black) that absorbs predetermined electromagnetic radiation for producing a coating that blocks the electromagnetic radiation, as well as dry cells surrounded by a binder material. Multiple light scattering effects through (caused by) and among the porous particles and the surrounding dry cells increase the path of radiation through the dry opaque layer. The likelihood of radiation encountering the opacifying colorant is increased by this greater path length.

Some particularly useful porous particles comprise a continuous polymeric phase and a first set of discrete pores dispersed within the continuous polymeric phase, wherein:

each porous particle has a mode particle size of at least 3 μm and up to and including 30 μm,

each porous particle has a porosity of at least 40 volume% and up to and including 65 volume%,

The continuous polymer phase comprises one or more polymers at least 70 wt.% of which is derived from one or more of cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate, such that the continuous polymer phase has a glass transition temperature (T) of at least 110 ℃ and up to and including 170 ℃, as determined using differential scanning calorimetry_g)，

The discrete pores have an average size of at least 50 nm and up to and including 1000 nm,

the porous particle further comprises a pore stabilizing hydrocolloid selected from the group consisting of carboxymethylcellulose, gelatin, a protein or protein derivative, polyvinyl alcohol or a derivative thereof, a hydrophilic synthetic polymer, and a water soluble microgel within at least a portion of the volume of the discrete pores, and

The porous particles comprise one or more amphiphilic low HLB block copolymers disposed at the interface of one or more discrete pores and the continuous polymeric phase.

adhesive material:

The foamable aqueous compositions and foamed aqueous compositions used in the present invention also comprise one or more binder materials that can serve as a "matrix" for all materials to hold together the necessary porous particles, additives, opacifying colorants, and any optional materials when applied to the interior surface of a porous substrate and dried to form a dry opacifying layer.

It is particularly useful that the binder material has the following properties: (a) it is water soluble or water dispersible; (b) it is capable of forming a stable foamed aqueous composition with the essential and optional components described herein; (c) it can be disposed onto a suitable substrate as described below; (d) it does not inhibit the aeration (foaming) process (described below); (e) it can be dried and also cross-linked (or cured) if desired; (f) it has good light stability and thermal stability; (g) it is film-forming but contributes to the flexibility of the foamed opacifying element and is therefore not too brittle, e.g. has a T of less than 25 ℃_g。

The choice of binder material may also be used to increase the laundering properties of the resulting foamed opacifying composition in the foamed opacifying element. In addition, the adhesive material may be used to provide a compliant tactile feel and flexibility, particularly when disposed on a porous substrate (e.g., fabric) intended for a window covering (e.g., drape). The adhesive material may be used in a foamed opacifying element to bind the porous particles together with other materials in the dry foam composition and to adhere both to the porous substrate.

the binder material may comprise one or more organic polymers which are film-forming and may be provided as an emulsion, dispersion or aqueous solution and which cumulatively provide the above-mentioned properties. It may also comprise a self-crosslinking or self-curable polymer, or it may comprise one or more polymers to which a crosslinking agent is added and which are therefore curable or capable of crosslinking (or curing) under the appropriate conditions.

Thus, if the adhesive material is crosslinkable (or curable) in the presence of a suitable crosslinking agent, such crosslinking (or curing) may be chemically activated by heat, radiation, or other known means. The curing or crosslinking agent serves to provide improved insolubility, cohesive strength, and adhesion to the porous substrate of the resulting dry foam composition. Curing or crosslinking agents are typically chemicals having functional groups that are capable of reacting with reactive sites in the binder material (e.g., functionalized latex polymer) under curing conditions, thereby creating a crosslinked structure. Representative crosslinking agents include, but are not limited to, polyfunctional aziridines, aldehydes, carbinol derivatives, and epoxides.

Useful binder materials include, but are not limited to, polyvinyl alcohol, polyvinyl pyrrolidone, ethylene oxide polymers, polyurethanes, urethane-acrylic copolymers, other acrylic polymers, styrene-acrylic copolymers, vinyl polymers, styrene-butadiene copolymers, acrylonitrile copolymers, polyesters, silicone polymers, or combinations of two or more of these organic polymers. Such binder materials are readily available from various commercial sources or may be prepared using known starting materials and synthesis conditions. The binder material may be anionic, cationic or nonionic in terms of net charge. One class of useful film-forming binder materials includes aqueous latex polymer dispersions, such as acrylic latexes, which may be ionic colloidal dispersions or nonionic colloidal dispersions of acrylate polymers and copolymers. For example, useful film-forming aqueous latexes include, but are not limited to, styrene-butadiene latexes, polyvinyl chloride and polyvinylidene chloride latexes, polyvinyl pyridine latexes, polyacrylonitrile latexes, and latexes formed from N-methylol acrylamide, butyl acrylate, and ethyl acrylate. Examples of suitable commercially available adhesive materials include NEOREZ under the trade name NEOREZ from DSM^® A-1150、NEOCRYL^®Those sold under the trade name RHOPLEX by Dow, A-6093^®Those sold under the trade name BUTOFAN by BASF, NW-1845K^®N S144 and BUTOFAN^®those sold by NS 222 under the trade name HYSTRETCH by Lubrizol^®And HYCAR^®Those sold, and resins sold by Royal Adhesives, e.g. PARANOL^® AC-2032。

The adhesive material typically has a glass transition temperature of less than 25 ℃, and more likely equal to or less than 0 ℃. The glass transition temperature can be determined using known procedures, and such values are known for many polymers that can be used as binder materials in the present invention. The binder material desirably has sufficient flexibility and tensile strength to maintain integrity when treated, particularly with porous textile substrates.

The one or more binder materials may be present in the foamable aqueous composition in an amount of at least 20 wt.%, or at least 20 wt.% and up to and including 60 wt.%, or typically at least 30 wt.% and up to and including 50 wt.%, based on the total weight of the total foamable aqueous composition (i.e., the total weight of all components including water).

Additive:

The foamable aqueous composition may comprise at least 0.0001 or at least 0.001 wt% or even at least 0.01 wt%, and up to and including 2 wt% or up to and including 5 wt% or even up to and including 20 wt% or even at least and including 30 wt% of one or more additives comprising at least one surfactant as defined below. Other useful additives include, but are not limited to, plasticizers, inorganic or organic pigments and dyes (e.g., pigments or dye colorants other than the opacifying colorants described below), flame retardants, biocides, fungicides, antimicrobials, preservatives, pH buffers, optical brighteners, tinting colorants, metal particles such as metal platelets or metal flakes, thickeners, and inorganic fillers (e.g., clays) that are not any of the other additive materials or opacifying colorants described below. These amounts refer to the total amount of one or more additives in the foamable aqueous composition and are based on the total weight of those compositions (including water). Each of these compositions may have a mixture of each type of additive or a mixture of two or more types of additives.

Any of these additives, or mixtures thereof, may be present in any location of the foamed aqueous composition including, but not limited to: a continuous polymeric phase; the volume of the first (or other) set of discrete holes; or both the first (or other) set of discrete pores of the porous particle and the continuous polymer phase. Alternatively, the one or more additives may be present only within the binder material, or within both the binder material and the porous particles.

In all embodiments, the (c) additive useful in the present invention is a different compound than (a) the porous particles, (b) the binder material, and (d) the opacifying colorant, as described herein.

As mentioned above, at least one additive is a surfactant, which is defined as a compound that reduces the surface tension in the composition. In most embodiments of the invention, such essential surfactants are blowing agents, which are used to create and enhance foam formation. In many such embodiments, the one or more (c) additives comprise one or more blowing agents (surfactants) and one or more foam stabilizers, which are also surfactants, that serve to structure and stabilize the foam. Examples of useful foaming agents (surfactants) and foam stabilizing dispersants include, but are not limited to, ammonium stearate, sodium lauryl sulfate, ammonium sulfosuccinate, disodium stearyl sulfosuccinate, ethoxylated alcohols; ionic, nonionic or anionic agents, such as fatty acid soaps or condensation products of fatty acids with alkylene oxides, for example condensation products of ethylene oxide with lauric acid or oleic acid; or esters of fatty alcohols, and the like, many of which are available from various commercial sources. Mixtures of blowing agents may be used if desired.

The relative amounts of each of these two types of (c) additives is not critical so long as the desired function is evident, which is the proper foaming properties required to prepare the foamed aqueous composition of the present invention, as well as the stability of the foamed aqueous composition during storage and during the manufacture of foamed opacifying elements. The optimum amounts of each of these additives can be determined by using routine experimentation and the teachings of the working examples below.

Other useful (c) additives include metal particles, which may be obtained as metal flakes or metal platelets and in dry form or in suspension from any available commercial source. Such metal flakes or flakes are essentially two-dimensional particles having opposing major surfaces or faces separated by a relatively small thickness dimension. The metal sheet may have a major surface Equivalent Circle Diameter (ECD) of at least 2 μm and up to and including a size range of 50 μm, where ECD is the diameter of a circle having the same area as the major surface. Examples of useful metal flakes include those available from Ciba Specialty Chemicals (BASF), such as aluminum flakes available as METASHEEN 91-0410 in ethyl acetate, and copper flakes available from various commercial sources. Further details of useful foils are provided in columns 11-12 of U.S. patent 8,614,039 (Nair et al). The metal particles, and in particular the metal flakes, described above can be in any suitable location in the foamable aqueous composition, but they are particularly useful when incorporated within the porous particles (e.g., within the volume of the discrete pores of the porous particles).

Useful biocides (i.e., antimicrobial or antifungal agents) that may be present as (c) additives include, but are not limited to, silver metal (e.g., silver particles, platelets, or fiber strands) and silver-containing compounds, such as silver chelates and salts, such as silver sulfate, silver nitrate, silver chloride, silver bromide, silver iodide, silver iodate, silver bromate, silver tungstate, silver phosphate, and silver carboxylates. In addition, copper metal (e.g., copper particles, flakes or fibers) and copper-containing compounds, such as copper chelates and copper salts, can be present as (c) additives for biocidal purposes. Mixtures of any of silver metal, silver-containing compounds, copper metal, and copper-containing compounds may also be present and used in this manner.

It may also be useful to include a thickener as (c) additive to modify the viscosity of the foamable aqueous composition and stabilize it, as long as aeration is not inhibited. The skilled person can optimize the viscosity in order to obtain the optimal aeration conditions and the desired foam density as described below. Depending on the method used to form the dry opaque layer on the porous substrate as described below, useful thickeners may be utilized to control the rheology of the foamable aqueous composition. A particularly useful rheology modifier is RHEOVIS^®PU 1214 (BASF) and ACRYSOL^® G111 (Dow Chemical Company)。

Particularly useful (c) additives include one or more tinting colorants that can be used to provide a particular observable color, tint, or hue in the resulting foamed opacifying element. These materials are not selected to provide the opacifying properties described below for the opacifying colorants, and thus the tinting colorants are intended to be materials other than opacifying colorants.

Mixtures of tinting colorants may be present in the foamable aqueous composition, and they may differ from each other in composition and amount. The desired coloration or hue may be obtained using the following means: the particular tinting colorants can be used in combination with the opacifying colorants described below to offset or alter the original color of the foamed opacifying element (without such materials) to provide greater whiteness (or brightness) in the final "color" (or tint). One or more tinting colorants may be incorporated within the porous particles (within the volume of the discrete pores, within the continuous polymeric phase, or at both locations), or they may be uniformly dispersed in the binder material. In some embodiments, the tinting colorant may be incorporated into the same porous particle that also includes an opacifying colorant (as described below). Alternatively, one or more tinting colorants may be present both within the porous particles (where appropriate) and within the binder material.

in some embodiments, a first porous particle population described herein comprises an opacifying colorant as described below, and another porous particle population described herein comprising a tinting colorant can be mixed with the first porous particle population. The two sets of porous particles may comprise the same or different polymers in the continuous polymer phase.

the one or more tinting colorants can be present in the foamable aqueous composition in an amount of at least 0.0001 wt%, or more typically at least 0.001 wt% and up to and including 3 wt%, based on the total weight of the foamable aqueous composition (including water). The tinting colorant may be a dye or organic pigment that is soluble or dispersible in the organic solvent and polymer used to prepare the porous particles, and thus may be included in the oil phase used to prepare such porous particles. Alternatively, the tinting colorant may be predominantly a water-soluble or water-dispersible material and included in the aqueous phase used to prepare the porous particles.

It may also be useful to include one or more optical brighteners as (c) additive to increase the whiteness (brightness or "fluorescence" effect) of the final coloration in the foamed opacifying element. Fluorescent whiteningThe agent (optical brightener) is sometimes referred to in the art as a "fluorescent whitening agent" ("fluorescent brightener" or "fluorescent brightener"). Typically, such materials are organic compounds selected from the known classes of compounds: derivatives such as stilbene and 4, 4' -diaminostilbene (e.g. bistriazinyl derivatives); derivatives of benzene and biphenyl (e.g., styril derivatives); a pyrazoline; derivatives of bis (benzoxazol-2-yl); coumarin; a quinolone; a naphthalimide; s-triazine; and pyridotriazole. Specific examples of optical brighteners may be mentioned in the list including "Fluorescent Whitening Agents", Kirk-OthmerEncyclopedia of Chemical Technology, fourth editionVol.11, Wiley&Sons, 1994, among various publications. One or more such compounds may be present in an amount of at least 0.01 weight percent and up to and including 2 weight percent, all based on the total weight of the foamable aqueous composition.

When present, the one or more optical brighteners can be at one or more locations in the foamable aqueous composition. For example, optical brighteners may be present in the binder material. Alternatively, the optical brightener may be present within the continuous polymeric phase of the porous particles; within the volume of discrete pores in the porous particle; or both the volume of the discrete pores of the porous particle and the continuous polymer phase.

in many useful embodiments, the (c) additive comprises two or more materials selected from the group consisting of: surfactants as blowing agents, foam stabilizers, toners, optical brighteners, flame retardants, biocides and inorganic fillers (e.g. clays).

(d)Water:

Water is the primary solvent used in the foamable aqueous composition used in the present invention. By "predominantly" is meant that water comprises at least 75 weight percent and more likely at least 80 weight percent and up to and including 100 weight percent of the total solvent weight, based on the total weight of the solvent. The auxiliary solvent that may be present should not adversely affect or damage the other components in the composition, i.e., the porous particles, the binder material, the one or more additives, and the opacifying agent. Such auxiliary solvents should also not adversely affect the formation of the foamable aqueous composition or its use to prepare foamed opacifying elements. Such auxiliary solvents may be water-miscible organic solvents, such as alcohols and ketones.

The solvent (primarily water) then comprises at least 30 wt% and up to and including 65 wt%, or typically at least 40 wt% and up to and including 60 wt% of the total weight of the foamable aqueous composition.

(e)Opaque colorant:

The opacifying colorants used in the present invention may be a single colorant or selected from any suitable combination of colorants such that the single colorant or colorants form an "opacifying colorant" that absorbs predetermined electromagnetic radiation (as defined above) to provide opacifying properties (or suitable opacity). The opacifying colorant may be a soluble dye or pigment or a combination of each or both types of material. The opacifying colorant is different from all compounds defined above as (c) additives.

In most embodiments, one or more opacifying colorants are present within the porous particle within the volume of the first (or another) set of discrete pores, within the continuous polymeric binder of the porous particle, or within both the volume of the first (or another) set of discrete pores and the continuous polymeric binder of the porous particle. This is very advantageous because the porous particles can be used to "encapsulate" various opacifying colorants as well as tinting colorants and other (c) additives so that they remain isolated from the other components of the foamable aqueous composition and, in addition, are not exposed to the environment during sewing or upon surface damage of the foamed opacifying element. However, in some embodiments, it may be useful to incorporate the opacifying agent alone or additionally within the binder material in which the porous particles are dispersed.

As used herein, an "opaque colorant" includes one or more colorant materials, selected individually or in combination, to provide a barrier to predetermined electromagnetic radiation (as described above). While opaque colorants may provide some coloration or desired shade, they are not intentionally selected for this purpose and are therefore materials selected to be different from the hueing colorants described above.

Examples of opaque colorants that can be used alone or in combination include, but are not limited to, neutral or black pigments or dyes, carbon black, black iron oxide, graphite, aniline black, anthraquinone black, and combinations of colored pigments or dyes, such as combinations of two or more cyan, magenta, green, orange, blue, red, and violet dyes. The present invention is not limited to the specific opaque colorants described herein, but these are considered representative and as suitable guidance to the skilled person in designing other combinations of opaque colorants for the desired absorption in the predetermined electromagnetic radiation. Carbon black or neutral or black pigments or dyes (or combinations thereof) are particularly useful as opacifying colorants, of which there are many types available from commercial sources. Combinations of dyes or pigments, such as subtractive primary colored pigments (cyan, magenta, and yellow pigments), can also be used to provide "black" or visually neutral opaque colorants.

The opacifying colorant can generally be present in the foamable aqueous composition in the following amounts: at least 0.001 wt% and up to and including 0.5 wt%, or at least 0.003 wt% and up to and including 0.2 wt%, all based on the total weight of the foamable aqueous composition (including the weight of the solvent). These amounts refer to the total amount of one opacifying colorant or a mixture of opacifying colorants. For example, as mentioned above, an opaque colorant can comprise a combination of two or more component colorants (e.g., a combination of dyes or a combination of pigments) designed in hue and amount such that the combination meets the desired properties described herein.

In some embodiments, the opacifying colorant is carbon black present in an amount of at least 0.003 weight% and up to and including 0.2 weight%, based on the total weight of the foamable aqueous composition.

In some embodiments, if the opacifying colorant is in the form of a pigment, it can be ground to a fine particle size and then encapsulated within the volume of the discrete pores of the porous particles by incorporating the ground pigment into the aqueous phase used to prepare the porous particles. Alternatively, the opacifying colorant may be incorporated into the continuous polymeric phase of the porous particles by incorporating the opacifying colorant into the oil phase used to prepare the porous particles. Such placement can be achieved during the manufacture of porous particles using the teachings provided herein and the teachings provided in the references cited herein.

In some embodiments, it may be useful to incorporate or arrange at least 95% (by weight) of the total opacifying colorant (or combination of component colorants) within the porous particles (in the volume of the discrete pores, the continuous polymer phase, or both), and to incorporate the remainder, if present, into the binder material. However, in many embodiments, 100 weight percent of the opacifying colorant is incorporated into the porous particles. For example, greater than 50 weight percent of the total opacifying colorant can be disposed within or incorporated into the continuous polymeric phase of the porous particles, and the remainder can be incorporated into the volume of the discrete pores.

Opacifying colorants useful in the practice of the present invention may be incorporated into the volume of the discrete pores of the individual porous particles, for example, by incorporating them into the first aqueous phase to form a water-in-oil emulsion, or into the continuous polymeric phase of the individual porous particles by incorporating them into the oil phase. In some embodiments, the opacifying colorant may be incorporated into the first aqueous phase in the form of a dispersion of ground solid particles of the opacifying colorant. The preparation of the milled solid particle dispersion may comprise combining the opacifying colorant particles to be reduced in size with a dispersant and a liquid medium, such as water or ethyl acetate, in which the porous particles are to be dispersed (when the opacifying colorant is incorporated into the continuous polymeric phase of the particles) in a suitable mill in which the porous particles are reduced in size and dispersed. The dispersant, an important ingredient in milling, may be selected to allow the opacifying colorant particles to be milled down in the liquid medium to a size small enough to be incorporated into the discrete pores of the porous particles. The dispersing agent may be selected to achieve effective opacifying colorant particle size reduction during milling, to provide good colloidal stability of the opacifying colorant particles to prevent agglomeration after milling, and to impart desired properties to the final foamed aqueous composition containing the opacifying colorant and the porous particles containing the opacifying colorant. Alternatively, the opacifying colorant may also be incorporated into the continuous polymeric phase in the form of a masterbatch of opacifying colorant and a suitable resin.

foamed aqueous composition

The foamed aqueous composition can be prepared using the procedure described below, wherein an inert gas (e.g., air) is mechanically incorporated into the foamable aqueous composition as described above, the procedure being designed to provide at least 0.1 g/cm²And up to and including 0.5 g/cm³or more likely at least 0.15 g/cm³And up to and including 0.4 g/cm³The foam density of (a). Foam density can be determined gravimetrically by weighing a known volume of the foamed aqueous composition.

the foamed aqueous composition typically has at least 35% solids and up to and including 70% solids, or more particularly at least 40% solids and up to and including 60% solids.

The essential components (a) to (e) of the foamed aqueous composition are generally present in the same amounts as in the foamable aqueous composition (described above) because the foaming process does not significantly increase or decrease the amount of such components.

For example, based on the total weight of the foamed aqueous composition, (a) the porous particles (as described above) may be present in the foamed aqueous composition in the following amounts: at least 0.05 wt% and up to and including 15 wt%, or typically at least 0.5 wt% and up to and including 10 wt%.

The one or more (b) binder materials (as described above) may be present in the following amounts based on the total weight of the foamed aqueous composition: at least 20 wt% or at least 25 wt% and up to and including 70 wt%, or typically at least 30 wt% and up to and including 50 wt%. Additionally, one or more of the binder materials in the foamed aqueous composition may be curable.

The one or more (c) additives (as described above) may be present in the following amounts based on the total weight of the foamed aqueous composition: at least 0.0001 wt% and up to and including 30 wt%, or typically at least 0.001 wt% or even at least 0.01 wt% and up to and including 20 wt%. (c) At least one of the additives is a surfactant as described above, and in a particularly useful embodiment, (c) the additive comprises a blowing agent and a foam stabilizer. Other useful (c) additives may be present as mentioned above for the foamable aqueous composition, in amounts also as mentioned above. For example, some particularly useful embodiments of the foamed aqueous composition, (c) the additive comprises two or more materials selected from the group consisting of: surfactants as blowing agents, surfactants as foam dispersants, toners, optical brighteners, flame retardants, biocides and inorganic fillers (e.g. clays).

Component (d), water, is also present as the predominant solvent (at least 75% by weight of the total solvent weight), and all solvents are present in an amount of at least 30% and up to and including 70% by weight, or typically at least 40% and up to and including 60% by weight, based on the total weight of the foamed aqueous composition.

(e) The opacifying colorant (as described above) is typically present in any suitable amount to provide the desired appearance, coloration, and opacity in the resulting foamed (and dried) opacifying element. In many embodiments, the one or more opacifying colorants may be present in an amount of at least 0.001 wt%, or at least 0.001 wt% and up to and including 0.5 wt%, or even in an amount of at least 0.003 wt% and up to and including 0.2 wt%, especially when the opacifying colorant is carbon black, all weights based on the total weight of the foamed aqueous composition.

in some embodiments, the foamed aqueous composition comprises at least 0.5 wt% and up to and including 10 wt% of porous particles (as described above) having a mode particle size of at least 3 μ ι η and up to and including 30 μ ι η, based on the total weight of the foamed aqueous composition. In addition, the discrete pores in such porous particles may have an average pore size of at least 100 nm and up to and including 7000 nm.

In addition, the foamed aqueous composition may further comprise at least 0.001 weight percent of an opacifying colorant (described above) within the porous particles. For example, some opacifying colorants may be carbon black and are present in an amount of at least 0.003 weight% and up to and including 0.2 weight%, based on the total weight of the foamed aqueous composition.

Such opacifying colorants may be located (i) within the continuous polymeric phase of the porous particles; (ii) the volume of discrete holes; or (iii) both the volume of the discrete pores and the continuous polymer phase of the porous particles.

In some embodiments of the foamed aqueous composition, the porous particles that can be used further comprise at least a second set of discrete pores (different from the "first" set of discrete pores), and the opacifying colorant or tinting colorant can be present within the continuous polymer phase, within the volume of the second set of discrete pores, or within both the continuous polymer phase and the volume of the second set of discrete pores. The first and second (or additional) sets of discrete pores may be incorporated into the porous particles using the fabrication techniques described in the several references cited above, including U.S. patent 8,110,628 (Nair et al).

Foamed opaque element

The foamed opacifying element according to the invention can be prepared using the methods described below. Such articles comprise a porous substrate and at least one dry foam composition disposed on an interior surface of the porous substrate to form a dry opaque layer. As described in more detail, each porous substrate has two supporting (planar) sides, i.e., opposing outer and inner surfaces as defined above.

Each dry foam composition is derived from a foamed aqueous composition as described above. Each dry foam composition comprises at least the essential components (a) to (e) described above, all of which and the respective amounts are described in more detail above.

Component (a) the porous particles are present in an amount of at least 0.1 wt% and up to and including 40 wt% or at least 0.5 wt% and up to and including 10 wt% of porous particles (described in detail above) based on the total weight of the dry foam composition, particularly when the porous particles have a mode particle size of at least 2 μm and up to and including 50 μm (or at least 3 μm and up to and including 30 μm), and the first set of discrete pores of the porous particles have an average pore size of at least 100 nm and up to and including 7,000 nm.

Additionally, the dry foam composition comprises component (b) a binder material in at least partially cured or crosslinkable form that is at least 10 wt% and up to and including 70 wt%, or at least 20 wt% and up to and including 60 wt% of one or more at least partially cured binder materials. Such at least partially cured adhesive materials are obtained by at least partially curing or crosslinking (described below) the adhesive materials described above. The amounts mentioned are based on the total weight of the dry foam composition. The one or more binder materials each have a T of 25 ℃ or less, or 0 ℃ or less_g。

one or more (c) additives (at least one of which is a surfactant) are present in an amount of at least 0.2 wt% and up to and including 50 wt%, or at least 1 wt% and up to and including 45 wt%, such additives being selected from blowing agents, foam stabilizers, plasticizers, inorganic or organic pigments and dyes (e.g., pigments or dye colorants other than the opaque colorants described below), flame retardants, antimicrobials, fungicides, preservatives, pH buffers, optical brighteners, tinting colorants, metal particles (e.g., metal platelets or metal flakes), thickeners, and inorganic fillers (e.g., clays) that are not any of the other additive materials or opaque colorants described herein, all of which are described in more detail above. The amounts are based on the total weight of the dry foam composition. As mentioned above, most embodiments include at least one surfactant as the blowing agent and at least one foam stabilizer.

Particularly useful one or more (c) additives comprise two or more materials selected from the group consisting of: foaming agents, foam stabilizers, tinting colorants, optical brighteners, flame retardants, biocides, and inorganic fillers (e.g., clay).

Accordingly, the foamed opacifying element may comprise one or more tinting colorants as (c) additive in the dry foam composition in an amount of at least 0.0001% and up to and including 3% by weight, based on the total weight of the dry foam composition. Such tinting colorants may be present at least in the porous particles, and may also be elsewhere.

It is also useful to include as (c) additive one or more optical brighteners in an amount of at least 0.001 wt% and up to and including 0.4 wt%, based on the total weight of the dry foam composition.

The dry foam composition is "substantially" dry in nature, meaning that it comprises less than 5 wt.%, or even less than 2 wt.% of an aqueous medium (including water and any other solvents), based on the total weight of the dry foam composition. The amount may not include any water that may be present in the discrete pores of the porous particle. The dry foam composition in the dry opaque layer typically comprises at least 90% solids, or at least 95% solids, or even at least 98% solids.

The dry foam composition may also contain at least 0.002 wt%, or even at least 0.02 wt% and up to and including 2 wt%, or up to and including 1 wt% of one or more (e) opacifying colorants (as described above) that absorb all wavelengths of predetermined electromagnetic radiation (as defined above). Details of such opacifying colorants are as described above, and the amounts are based on the total weight of the dry foam composition. Such opacifying colorants may be present (a) within the porous particles or (b) within the binder material, or both (a) and (b) components.

In some embodiments, carbon black is present as (e) an opacifying colorant in an amount of at least 0.002% by weight and up to and including 1% by weight, based on the total weight of the dry foam composition.

In many embodiments of the foamed opacifying element, an opacifying colorant (e.g., carbon black) may be present within the continuous polymeric phase of the porous particles; the volume of discrete holes; or both the volume of discrete pores and the continuous polymer phase of the porous particles.

the foamed opaque element is specifically designed to have a single dry opaque layer with the components disposed on a porous substrate such that the single dry opaque layer in the element exhibits a Light Blocking Value (LBV) of at least 4 or more likely at least 5. For this purpose, the light blocking value can be determined as described above.

In addition, such dry opaque layers exhibit a light reflectance (opacity) of greater than 40% as measured for the Y tristimulus value. For this purpose, the light reflectance (brightness) is determined as described above.

Dry porous substrates useful in the practice of the present invention can comprise a variety of porous materials such as knitted, woven and nonwoven textile fabrics composed of polyester, polyamide, triacetate, acrylic, elastomer, nylon or mixtures thereof, or knitted, woven and nonwoven fabrics of cotton, linen, rayon, polyolefin, cotton, wool, porous glass, fiberglass fabrics or felts or mixtures thereof, or porous polymeric films [ such as porous films derived from: triacetyl cellulose, polyethylene terephthalate (PET), diacetyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, polyethersulfone, polyacrylic-based resins such as polymethylmethacrylate, polyurethane-based resins, polyesters, polycarbonates, aramids, polyolefins (e.g., polyethylene and polypropylene), polymers derived from vinyl chloride (e.g., polyvinyl chloride and vinyl chloride/vinyl acetate copolymers), polyvinyl alcohol, polysulfones, polyethers, polynorbornene, polymethylpentene, polyetherketones, (meth) acrylonitrile ], porous paper or other porous cellulosic materials, canvas, porous wood, porous gypsum, and other porous materials that will be apparent to those skilled in the art. The dry thickness of the porous substrate may vary so long as they are suitable for the desired foamed opacifying element. In most embodiments, the dry porous substrate thickness is at least 50 μm.

Particularly useful porous substrates include porous woven webs (e.g., flexible porous woven webs) composed of synthetic materials such as polyester, nylon, acrylic, or synthetic blends containing natural fibers.

Typically, foamed opacifying elements according to the invention are designed to have a single dry opacifying layer disposed on the inner surface of the porous substrate as described above, and such single dry opacifying layer may be the outermost layer disposed on the inner porous substrate. In some other embodiments, the dry non-opaque layer may be disposed on a single dry opaque layer, or it may be disposed on the opposite outer surface of the porous substrate. Such a dry non-opaque layer may be designed to have any of components (a) to (c) described above, but it does not comprise (e) an opacifying colorant as defined herein. Useful dry non-opaque layers can be designed to have various functions, such as coefficient of friction, texture and feel, antimicrobial properties, antiblocking, and color change.

An attractive finish (finish) can be imparted to the foamed opaque element by, for example, flocking the foamed aqueous composition disposed on the porous substrate. Before or during drying, flock or very short (0.2 mm and up to several mm) fibers can be arranged on the foamed aqueous composition by electrostatic or mechanical techniques.

The dried opaque layer or dried opaque layer may be treated with an antiblock agent (e.g., silicone) to reduce tack and improve the surface coefficient of friction. Once applied, the blocking agent may be dried on the appropriate layer.

In the foamed opacifying element, a thermal colorant image resulting from the thermal colorant transfer process is disposed on at least the opposing outer surface of the porous substrate, the dry opacifying layer, or both the opposing outer surface and the dry opacifying layer. Details regarding providing such thermal colorant imaging are provided below.

method for producing foamed opaque elements

A foamed opaque element was prepared by: the dry opaque layer is first provided from a foamable aqueous composition as described above, which composition comprises the essential components (a) to (e) in the amounts described.

Aerating the foamable aqueous composition to provide a composition having at least 0.1 g/cm³And up to and including 0.5 g/cm³Or at least 0.15 g/cm³And up to and including 0.4 g/cm³the foamed aqueous composition of (a). Such an aeration procedure may be carried out using any suitable conditions and equipment that will be readily apparent to those skilled in the art to produce a "foam" in the presence of a blowing agent that is the (c) additive surfactant described above. For example, can be obtained byAeration is carried out by mechanically introducing air or an inert gas (e.g., nitrogen or argon) in a controlled manner. High shear mechanical aeration may be performed using sonication or high speed mixers, such as those equipped with cowles blades, or with commercially available rotor stator mixers with interdigitated pins, such as Oakes mixers or Hobart mixers, by introducing air under pressure or by sucking atmospheric air into the foamable aqueous composition via the whipping action of the mixer. Suitable foaming equipment can be used in a manner that provides the desired foam density with moderate experimentation. It may be useful to chill or cool the foamable aqueous composition below ambient temperature to increase its stability by increasing its viscosity and to prevent the foamed aqueous composition from collapsing. Such chilling operation may be performed shortly before, shortly after or during the aeration procedure. The stability of the foamed aqueous composition may also be enhanced by the presence of a foam stabilizer as another additive (c).

Once the foamed aqueous composition has been formed, it is typically disposed on the interior surface of a suitable porous substrate (described above). This procedure may be performed in any suitable manner that does not undesirably reduce the foam density (or foam structure) of the foamed aqueous composition. For example, the interior surfaces of the porous substrate can be coated with the aqueous foam composition using any suitable known coating equipment (float knife, hopper, blade, or gap) and coating procedures including, but not limited to, knife coating, gap coating, slot die coating, X-slide hopper coating, or "knife over roll" operations, particularly when multiple layers are applied to the interior surfaces. If the dry opaque layer is the only layer to be formed on the inner surface, the foamed aqueous composition may be applied using knife coating, gap coating, slot die coating, or "knife over roll" coating. Useful layer forming (coating) means are described, for example, in us patent 4,677,016 (mentioned above).

Thus, the foamed aqueous composition can be disposed directly onto the interior surface of a porous substrate such as a porous woven cloth fabric, a glass fiber fabric, a porous polyester fabric, or a cellulosic material ("directly" meaning without an intervening layer or intermediate layer).

When multiple layers are to be disposed on the inner surface of the porous substrate, a single dry opaque layer may be disposed thereon using a suitable coating means as described above, and an outermost non-opaque layer may be disposed on the dry opaque layer. Alternatively, a non-opaque layer may be disposed on the inner surface below the dry opaque layer.

Once the foamed aqueous composition has been disposed on the interior surface of the porous substrate, it is dried to remove at least 95% of the original water, and at least partially cured (meaning that the binder material(s) are at least partially cured or crosslinked), either simultaneously or in any order, to provide a dried foamed composition (and a dried opaque layer) on the interior surface of the porous substrate. Drying and at least partial curing may be achieved by any suitable means, for example by heating with warm or hot air, microwave or IR radiation at a temperature and time sufficient to at least dry and at least partially cure (for example at less than 180 ℃). Curing of the binder material may be facilitated by heat or radiation or other conditions to which the binder material responds to facilitate crosslinking. In some embodiments, a suitable functionalized latex composition is used as the binder material. Upon heating, the adhesive material dries and possible curing or crosslinking reactions occur between the reactive side groups of the appropriate curable polymer chains. If the particular adhesive material is not itself thermally reactive, a suitable catalyst or curing (crosslinking) agent may be added to the foamable aqueous composition to promote curing or crosslinking.

After drying and at least partial curing, the dried foam composition on the inner surface is then crushed or densified to form a dried opaque layer. This process may be performed in any suitable manner, but it is typically performed by applying pressure to the dry foam composition on the inner surface, for example, by passing the porous substrate with the dry foam composition through a compression calendaring operation, a pressing operation, or an embossing operation, or a combination thereof. For example, the foamed opaque element can be passed through a combination of calendering and embossing rollers to reduce the thickness of the dried foam composition and densify the foam. During such operations, the thickness of the dry foam composition may be reduced by at least 20%. This process of crushing the dried foam composition may be considered a "densification operation" in that the dried foam composition is made more dense as it is pressed together on the inner surface. The thickness of the dried foam composition before and after crushing (densification) can be determined by known techniques, such as laser profilometry. After drying and crushing, the foamed opacifying element typically has a light-blocking value (LBV) of at least 4, or at least 5, as determined as described above.

the crushing or densification process described above may be carried out at any suitable temperature, including room temperature (e.g., 20 ℃) and up to and including 90 ℃, or more likely at a temperature of at least 20 ℃ and up to and including 80 ℃.

After densifying the dry foam composition, the dry opaque layer may be subjected to conditions that promote further curing, such as those described above for the initial drying operation.

It is also possible to provide an embossed design on the outermost layer (e.g., on the dry opaque layer or on the dry opaque layer) during densification operations, such as drying the outermost layer, e.g., by patterned embossing or calendaring, to produce selected regions of high or low opacity and thickness. The resulting embossed design can be seen from either side of transmission.

Providing thermal dye images

as described above, the foamed opacifying element according to the invention comprises one or more thermal colorant images disposed on the opposing outer surface, on the dry opacifying layer (on the inner surface), or on both the opposing outer surface and the dry opacifying layer. Each of these thermal colorant images is obtained using a thermal colorant transfer method described in more detail below. In most embodiments, one or more thermal colorant images (e.g., thermal dye images) are provided only on the opposite outer surfaces of the porous substrate.

in some embodiments, thermal colorant images can be provided by what can be referred to as "direct disperse dye printing" in which one or more thermal colorants are applied to a pretreated fabric substrate without the use of a thermal donor element and heated thereon to "thermally fix" them to the pretreated fabric substrate.

typically, such thermal colorant images are provided by overlaying a colorant donor layer of a thermal donor element (described below) and the surface of the foamed opaque element to be printed (or imaged). For example, the opposite outer surface of the porous substrate and the colorant donor layer may be superposed, or the dried opaque layer and the colorant donor layer may be superposed. In any of these arrangements, the desired thermal colorant image (pattern) is transferred with or without pressure by appropriate application of heat directed from the "back side" of the thermal donor element (the thermal donor element support side opposite the colorant donor layer) to the stacked article.

the term "superposed" means that the colorant donor layer and the foamed opaque element are in intimate contact with little or no air gap.

Thermal donor elements useful in the practice of the present invention can be provided in a variety of ways. For example, thermal donor elements are available from a wide variety of commercial sources, and such thermal donor elements typically comprise a suitable paper (cellulosic) or polymer (e.g., polyester) support onto which has been applied a single or multi-color image (or pattern) of one or more "inks" using inkjet printing, gravure printing, rotary screen printing, or other means. Such a single color or multi-color image (or pattern) is provided as a "mirror" (negative) image or pattern, such that the image or pattern provided on the foamed opaque element is a "positive" image or pattern.

In other embodiments, the thermal donor element can be provided similar to those commercially available from various sources around the world. Such elements are sometimes referred to as hot dye strips and have various colors that can be thermally printed, or they may have various colored dye patches (patches) on a single web or roll of hot donor material. Each individual band or block contains an appropriate sublimable dye.

In such embodiments, the thermal colorant donor element typically comprises a support having thereon a colorant donor layer (e.g., a dye donor layer) comprising at least one thermally transferable colorant, such as a sublimable dye or pigment. Such transferable compositions may also be referred to as "inks".

Many useful ink or dye colorants are known in the commercial trade or in the literature, and the present invention is not limited to a particular material, so long as they can be incorporated into the colorant dye donor layer and transferred to the foamed opaque element described above. Representative thermal donor elements can be constructed as described in U.S. Pat. Nos. 4,916,112 (Henzel et al), 4,927,803 (Bailey et al), 5,023,228 (Henzel) and 7,153,626 (Foster et al).

In some of these embodiments, the thermal donor element can comprise a paper (cellulosic) or polymeric (e.g., polyester) support coating or an ink-jet printed image in a band with continuous repeating areas (patches) or patterns or cyan, magenta, yellow, or black dyes or inks. Thermal colorant transfer can be performed sequentially or simultaneously to provide a multi-color image.

a thermally transferable "ink" as used herein may comprise one or more dyes, pigments or other colorants, and optionally one or more binder materials or carriers as will be readily apparent to those skilled in the art. The heat-transferable colorant, such as a dye, may be selected by taking into consideration the color tone, light resistance, solubility in any binder material, type of support, and heat transfer conditions. Many examples of useful thermally transferable dyes are described in the references cited in U.S. patent application publication 2014/0071218 (Dontula et al) [0115 ].

useful thermally transferable colorants (e.g., dyes) can be employed alone or in combination, and can be provided in the thermal donor element in the following amounts: at least 0.01 g/m based on dry coverage of the colorant donor layer²And up to and including 5 g/m²Or more likely at least 0.05 g/m²And up to and including 2 g/m²。

Representative sublimable dyes (inks) useful in the practice of the present invention include Kiian Digitar E-gold sublimation inks for transfer, which can be applied to a substrate, such as Kiian Digitar paper, in any desired pattern or image using an Epson piezoelectric printhead. The resulting thermal donor element can be used immediately or stored for later use. The thermal transfer of ink from the thermal donor element to the foamed opaque element can be carried out using any suitable thermal transfer device, such as a Practix OK-405 rotary transfer machine having heated cylinders or calender rolls against which the thermal donor element and the desired surface of the porous substrate to be printed are superposed by and in contact between a heated cylinder and an endless belt. Typically, heat transfer can be accomplished using a hot press for the sheet material or using heated calender rolls for the roll of material.

In many embodiments, image transfer can be achieved by applying heat at least 180 ℃ and up to and including 220 ℃, e.g., 200 ℃, optionally under suitable pressure. The residence time required for sufficient sublimation, transfer, and condensation of the image is typically at least 15 seconds and up to and including 90 seconds, such as at least 30 seconds and up to and including 60 seconds. The temperature and time for this thermal transfer process can be adjusted by the skilled person using routine experimentation such that at least 60% or even at least 80% by weight of the colorant (ink) in the thermal donor element is transferred to the foamed opacifying element. The amount of such thermal transfer can be assessed by measuring the weight of the thermal donor element before and after thermal image transfer, or by measuring the transmission density of the image or pattern on the thermal donor element before and after thermal image transfer using a commercial densitometer.

in addition to providing a colored image or pattern by thermal transfer, the present invention may also include providing a protective transparent film (laminate) to the porous substrate by thermal transfer. Such a protective transparent film or overcoat can be applied over or on the surface opposite the thermally transferred colorant image or pattern. The protective transparent film may be provided with a separate thermal donor element (or tape), for example, as described in U.S. patent application publication 2010/021887(Vreeland et al). Further details of such transparent laminates are provided in [0118] - [0120] of u.s.'887 (mentioned above). Alternatively, the protective transparent film can be provided as separate blocks in a thermal donor element having one or more blocks of thermally transferable colorant and a block providing the protective transparent film.

for example, in some embodiments, a protective transparent film may be thermally applied (printed) over the color thermal print image or pattern on the opposite outer side of the porous substrate. In other embodiments, a protective transparent film may be thermally applied (printed) over the color thermal print image or pattern on the dry opaque layer on the inside of the porous substrate. In still other embodiments, the protective transparent film may be thermally applied (printed) on the opposite outer surface without the color thermal print image or pattern, with such color thermal print image or pattern disposed on the dry opaque layer on the inside of the porous substrate.

The present invention can also be used to thermally transfer metal images or patterns using a uniquely designed thermal donor element containing a transferable metal in the metal donor layer rather than a dye or other colorant to achieve various metallic effects on the thermally transferred color image on either side of the porous substrate. Details regarding such materials and their use are described in US' 218 (mentioned above) [0121] and publications cited therein.

The present invention provides at least the following embodiments and combinations thereof, but as the skilled person will appreciate from the teachings of the present disclosure, other combinations of features are within the scope of the invention:

1. A method of providing a foamed opaque element comprising a thermal colorant image, comprising:

Providing a porous substrate having opposing outer and inner surfaces, the porous substrate further comprising a dry foam composition disposed as a dry opaque layer on the inner surface of the porous substrate,

Wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having at least 2 μm and up toA mode particle size of up to and including 50 [ mu ] m and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase has a glass transition temperature of greater than 80 ℃ and is comprised at a concentration of 20 wt% in ethyl acetate at 100s at 25 ℃^-1A polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) at least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) Less than 5 wt% water; and

(e) At least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs the predetermined electromagnetic radiation,

All amounts are based on the total weight of the dry foam composition,

wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, an

Providing a thermal colorant image on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer by thermal colorant transfer from a thermal donor element comprising a colorant donor layer comprising one or more thermal colorants.

2. the method of embodiment 1, wherein the thermal colorant image is a multicolor thermal colorant image provided by a plurality of thermal colorant transfer operations using a plurality of thermal donor elements.

3. The method of embodiment 1, wherein the thermal colorant image is a multicolor thermal colorant image provided by a multicolor mirror image on a single thermal donor element.

4. The method of any one of embodiments 1 to 3, wherein at least 0.01 g/m²And up to and including 5 g/m²Dry coverage to provide a thermal colorant image.

5. the method of any one of embodiments 1 to 4, wherein the one or more thermal colorants are one or more sublimable dyes.

6. The method of any one of embodiments 1 to 5, comprising:

providing a thermal colorant image by overlaying a colorant donor layer of a thermal donor element and a dry opaque layer, an

one or more thermal colorants are transferred imagewise (imagewise) from the colorant donor layer onto the dry opaque layer by applying heat to the thermal donor element, either in the presence or absence of pressure, on the side opposite the colorant donor layer.

7. The method of any one of embodiments 1 to 5, comprising:

Providing a thermal colorant image by superposing a colorant donor layer of a thermal donor element and an opposing outer surface of a porous substrate, an

One or more thermal colorants are imagewise transferred from the colorant donor layer to an opposing outer surface by applying heat to the thermal donor element, with or without pressure, on the side opposite the colorant donor layer.

8. The method of any one of embodiments 1 to 7, comprising:

Providing a thermal colorant image by: one or more thermal colorants are transferred image-wise from the colorant donor layer to the opposite outer surface of the porous substrate by thermal printing using a resistive head or a laser.

9. The method of any of embodiments 1 and 3 through 8 wherein the thermal donor element comprises a block of two or more different thermal dye blocks and a block comprising a transparent protective overcoat composition.

10. The method of any of embodiments 1 and 3 through 9, wherein the thermal donor element comprises a mirror image of an inkjet printed thermal colorant image.

11. The method of any of embodiments 1-10, wherein the porous substrate comprises polyester and the one or more thermal colorants are one or more thermally sublimable dyes.

12. the method of any one of embodiments 1 to 11, further comprising:

The metallic image is provided by heat transfer to any of the opposing outer surfaces, a dry opaque layer, or a thermal colorant image.

13. The method of any one of embodiments 1 to 12, further comprising:

Providing a dry non-opaque layer comprising a tinting colorant, a flame retardant, an antimicrobial agent, an antiblock agent, or a flocking agent on the dry opaque layer.

14. The method of any of embodiments 1 through 13, wherein the opacifying colorant is carbon black present in an amount of at least 0.002 weight% and up to and including 1 weight%, based on the total weight of the dry foam composition.

15. The method of any of embodiments 1 to 14, wherein the dry foam composition has at least 98% solids.

16. The process of any of embodiments 1 to 15, wherein the continuous polymer phase comprises at least 70 weight percent and up to and including 100 weight percent of one or more polymers derived from one or more of cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate, based on the total polymer weight in the continuous polymer phase.

17. the method of any of embodiments 1 through 16, wherein the porous particles are present in an amount of at least 0.5 weight% and up to and including 10 weight%, based on the total weight of the dry foam composition.

18. The method of any of embodiments 1 through 17, wherein the at least partially cured binder material is present in an amount of at least 20 weight percent and up to and including 60 weight percent, and has a glass transition temperature of less than 25 ℃.

19. the method of any of embodiments 1-18, wherein the at least partially cured binder material has a glass transition temperature of less than 0 ℃.

20. The method of any one of embodiments 1 to 19, wherein the one or more (c) additives comprise an antimicrobial agent comprising silver metal, a silver-containing compound, copper metal, a copper-containing compound, or a mixture of any of these.

21. The method of any of embodiments 1 to 20, wherein the one or more thermal colorants comprise sublimable cyan, yellow, magenta, or black dyes, or combinations thereof.

22. The method of any of embodiments 1-21, wherein the porous substrate comprises a porous woven web, a porous polymeric membrane, a porous cellulosic material, a porous ceramic material, or a porous glass material.

23. the method of any of embodiments 1-22, wherein the porous substrate comprises a polyester.

24. The method of any of embodiments 1-23, wherein the dry opaque layer is the only layer disposed on the porous substrate.

25. The method of any one of embodiments 1 to 24, further comprising disposing a dry non-opaque layer on the dry opaque layer.

26. The method of embodiment 25, wherein drying the non-opaque layer comprises a tinting colorant, a flame retardant, an antimicrobial agent, an antiblock agent, or a flocking agent.

27. The method of any of embodiments 1 to 26, wherein the dry foam composition comprises at least 0.5 wt.% and up to and including 10 wt.% of porous particles having a mode particle size of at least 3 μm and up to and including 30 μm, based on the total weight of the dry foam composition.

28. The method of any one of embodiments 1 through 27, wherein the one or more (c) additives further comprise metallic flakes present within the porous particles.

29. the method of any one of embodiments 1 to 28, wherein the surfactant of the one or more (c) additives is a blowing agent, and the one or more (c) additives further comprise a foam stabilizer.

30. The method of any of embodiments 1 to 29, wherein the one or more (c) additives further comprise a tinting colorant in an amount of at least 0.0001 weight% and up to and including 3 weight%, based on the total weight of the dry foam composition.

31. The method of any of embodiments 1 to 30, wherein the one or more (c) additives further comprise an optical brightener in an amount of at least 0.001 wt% and up to and including 0.4 wt%, based on the total weight of the dry foam composition.

32. The method of any one of embodiments 1 to 31, further comprising providing a transparent protective layer over the thermal colorant image.

33. A foamed opacifying element obtained from the method of any of embodiments 1 to 32, comprising a thermal colorant image, the foamed opacifying element further comprising a porous substrate having opposing outer and inner surfaces, the inner surface having a dry foam composition disposed thereon as a dry opacifying layer,

Wherein the dry foam composition comprises:

(a) At least 0.1 wt% and up to and including 40 wt% of porous particles, each porous particle comprising a continuous polymer phase and a first set of discrete pores dispersed within the continuous polymer phase, the porous particles having a mode particle size of at least 2 μm and up to and including 50 μm and a porosity of at least 20 vol% and up to and including 70 vol%, and the continuous polymer phase having a glass transition temperature of greater than 80 ℃ and being comprised at 100s at a concentration of 20 wt% in ethyl acetate at 25 ℃^-1A polymer having a viscosity of at least 80 centipoise and up to and including 500 centipoise at a shear rate of (a);

(b) At least 10 wt% of an at least partially cured binder material;

(c) At least 0.2 wt% of one or more additives comprising a surfactant;

(d) Less than 5 wt% water; and

(e) at least 0.002% by weight of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs the predetermined electromagnetic radiation,

all amounts are based on the total weight of the dry foam composition,

Wherein the dry opaque layer has a light blocking value of at least 4 and a light reflectance of greater than 40% as measured by the Y tristimulus value, and

Wherein the thermal colorant image is disposed on the opposing outer surface, the dry opaque layer, or both the opposing outer surface and the dry opaque layer.

34. The foamed opacifying element of embodiment 33, wherein the dried opacifying layer exhibits a light-blocking value of at least 5.

the following examples are provided to illustrate the practice of the invention and are not meant to be limiting in any way. The following materials were used in the examples.

materials used in the following examples:

the continuous polymer phase polymer used in the following examples is Eastman-phase cellulose acetate butyrate 381-0.5 (CAB), which is a cellulose ester, T_gat 130 ℃ (from Chem Point);

NALCO containing colloidal silica^®1060 available from Nalco Chemical Company in the form of a 50% by weight aqueous dispersion.

The poly (methylaminoethanol adipate) (AMAE) co-stabilizer was prepared using known procedures and starting materials.

Carboxymethyl cellulose (CMC, 250,000 kDa) was obtained from Acros Organics or from Ashland Aqualon as Aqualon 9M 31F. These products may be used interchangeably.

The procedure described in us patent 5,429,826 (Nair et al) was used to prepare amphiphilic block copolymers of polyethylene oxide and polycaprolactone (PEO-b-PCL)5K-20K, where the first figure is the molecular weight of the hydrophilic block segment PEO and the second figure is the molecular weight of the lipophilic block segment PCL.

TERGITOL^®15-S-7, C12-C14 secondary alcohol surfactant, having an HLB value of 12.4, available from Dow Chemical Corp.

fluorescent whitening agent TINOPAL^®OB CO is available from BASF Corporation.

The porous substrate used in the following examples was a porous woven 100% polyester fabric Coplane Muslin AS931/1 from Coplane Industries, having approximately 80-110 g/m²The weight of (c).

The opaque colorant of carbon black (K) used as the aqueous dispersion is hydrophobic surface-modified Regal 330 (Cabot Corp.).

SOLSPERSE^®43000 is a polyacrylate polymeric dispersant, available from Lubrizol Corp.

Drapery Compound (Drapery Compound) was obtained from Eagle Performance Products, where the adhesive material was a self-crosslinking terpolymer obtained from the polymerization of acrylonitrile, n-butyl acrylate, and ethyl acrylate, and having a glass transition temperature of-10 ℃.

Measurement:

The mode particle size of the porous particles used in the examples was measured using a Sysmex FPIA-3000 automated particle size analyzer from Malvern Instruments. Light scattering is used to determine the particle size of the dispersed pigment.

The porosity of the porous particles was measured using mercury intrusion porosimetry as described earlier.

the light blocking ability of each foamed opaque element in the examples was evaluated by measuring its Light Blocking Value (LBV) in transmitted light using a custom-made apparatus consisting of a fiber-optic xenon light source, a computer-controlled conversion stage, and a spectrophotometer. The optical fibers were positioned 10 mm above the fabric surface. A light detector is placed on the other side of the sample element directly below the optical fiber to quantify the amount of light passing through the sample element. By comparing the intensity of light (I) passing through the sample element with the intensity of light (I) reaching the detector in the absence of the sample element₀) And the light blocking value of each sample was calculated using the following equation:

-log₁₀ (I/I₀)。

The light reflectance (or brightness) of each sample element was determined by first measuring the spectral reflectance in the wavelength range 400-. The 0 to 100% reflectivity range was fixed using light traps and standard white tiles. The X, Y and Z tristimulus values for each dried opaque layer were also determined and used in conjunction with CIELab color space (standard D65 illuminant) to calculate specific values for the brightness (L), red-green characteristic (a), and yellow-blue characteristic (b) of each dried opaque layer. The Y tristimulus value was used as a measure of the light reflectance or "brightness" of each sample.

Thermal colorant transfer method:

The present method uses a thermal donor element comprised of an Epson 64 "additive Textile Paper sheet onto which the desired mirror image design or pattern has been ink-jet printed using an Epson F9200 ink-jet printer. The mirror image design or pattern comprises an ink containing a sublimable dye and the ink is manufactured by Kiian Digital.

Thermal colorant transfer is performed using a roll-to-roll machine with a large industrial sublimation calender. A nip (nip) is created by the roll and the belt in which the thermal donor element is brought into contact with the superposed opposing outer surfaces of the porous substrate (having the dry opaque layer on the inner surface) in the foamed opaque element. The nip residence time at 30 psi (207 kPa) and a nip temperature of 190 ℃ to 205 ℃ is 30 seconds, which causes sublimation of the sublimation dyes in the colorant donor layer and their adhesion to the opposing outer surfaces of the porous substrate. Transfer quality was assessed by visual inspection.

Preparation of opaque colorant dispersions of porous particles:

By mixing 10.42 wt% of dry pigment, SOLSPERSE^®43000 dispersant (20% by weight of opacifying colorant) and water are combined in a suitable milling vessel to prepare an opacifying colorant (K) carbon black dispersion. The opacifying colorant pigments are reduced in particle size by grinding them using ceramic media until all opacifying colorant particles are reduced to a diameter of 1 μm or less as determined by light microscopy. The dispersion was further diluted with water for incorporation into porous particles. Dv (volume weighted mean diameter in nanometers) was 101 nm.

Preparation of porous particles:

the following describes the porous particles used to make the foamed opacifying elements of the inventive examples.

Containing 0.8% by weight of opacifying colorant (K) in the discrete pores and 1% by weight in the continuous polymer phase CAB p1 porous particles of an amount% optical brightener

The aqueous phase was composed by dissolving 5 grams of CMC in 240.5 grams of distilled water and adding to 4.3 grams of D-K dispersion containing 18.6 weight percent carbon black. The aqueous phase was dispersed using a homogenizer in 831.8 g of an oil phase containing 97.7 g CAB, 2 g PEO-b-PCL and 1 g of Fluorescencetinopal as a whitening agent^®OBCO. Using a Silverson L4R homogenizer, a 975 g aliquot of the resulting water-in-oil emulsion was dispersed at 1200 RPM in 1625 g of 200 mM pH 4 acetate buffer for two minutes, then at 1000 psi (70.4 kg)_f/cm²) Homogenizing in a bore flow homogenizer (orific homogenizer) to form a water-in-oil-in-water double emulsion, the acetate buffer containing 39 grams of NALCO^®1060 colloidal silica and 9.75 grams of AMAE co-stabilizer. After diluting the water-in-oil-in-water emulsion with an equal weight of water, the ethyl acetate was removed under reduced pressure at 40 ℃. The resulting suspension of solidified porous particles was filtered and the resulting P1 porous particles were washed several times with water and then with 0.05 wt.% TERGITOL^®The 15-S-7 surfactant solution is washed. The isolated porous particles of P1 were then air dried. The porous particles had a mode particle size of 4.3 μm and a porosity of 40 volume%. Typically, the discrete pores contained in the porous particles prepared according to this procedure have an average diameter of 150 nm and up to and including 1,500 nm.

Foamable aqueous composition, foamed aqueous composition and preparation of foamed opacifying element：

Typically, the eagetex is prepared by incorporating porous particles into 48 wt.% solids^®C-3018 drape compound to prepare a foamable aqueous composition. For each foamed aqueous composition, a drape compound is added to an appropriately sized container. The porous particles were dispersed into the mixture by stirring at 1200 revolutions per minute for 30-60 minutes at ambient temperature with a Cowles blade 50 mm in diameter. The resulting dispersion (foamable aqueous composition) was used under pressure to prepare a foamed aqueous composition using an Oakes 2M laboratory mixer (model 2MBT 1A). Will have a coating knife of 0.18 g/cm³To 0.22 g/cm³The resulting foamed aqueous composition of density (d) is coated onto the surface of the porous substrate described above, dried at a temperature of 120 ℃ to 160 ℃ until the moisture content is less than 2% by weight, and crushed ("densified") under pressure on the porous substrate between rigid rollers.

Inventive example 1:Thermal printing on exterior surfaces

an image was thermally printed on the outer surface of the porous substrate in the dry opaque element in the following manner.

1400 g of EAGLETEX was used^®a foamable aqueous composition was prepared from a C-3018 drape compound and 100 g of a 49 wt% aqueous dispersion of P1 porous particles. The foamable aqueous composition was foamed (aerated) and the resulting foamed aqueous composition was coated onto the inner surface of the above-described porous substrate at 1 m/min in a coater using a coating knife having a gap of 2.54 mm (0.100 inch) and dried at 160 ℃. The resulting dry foam composition (dry opaque layer) in the resulting foamed opaque element contained 6.71 wt.% of the porous particles of P1, 0.0557 wt.% of carbon black (0.136 g/m based on dry weight)²Carbon black of (2). The foamed opacifying element exhibits a colour shift to 185 g/m²LBV of 5.8 by weight of dry opaque layer, light reflectance value of 52.

A sample of the foamed opaque element was thermally printed to impart a multi-colored floral image to the opposite exterior side of the porous substrate following the procedure described above with respect to the thermal colorant transfer method. Good heat transferability is demonstrated by the following facts: 70-80 wt% of the original colorant was transferred from the thermal donor element without risk of damaging the foamed opaque element. Print quality is acceptable for as many colors as are available in the thermal donor element. No delamination of the foamed opacifying element was observed during the thermal colorant transfer process and no significant outgassing from the foamed opacifying element was observed.

Inventive example 2:thermal printing on dry opaque layers

Another foamed opacifying element was prepared according to the invention using the foamable aqueous composition and foamed opacifying element described above for invention example 1, except that the multicoloured floral image was thermally printed onto the dry opacifying layer of the foamed opacifying element. For many colors, the thermal print quality is acceptable and no delamination or outgassing is observed during the thermal colorant transfer process.

Additional inventive embodiments:

in some other inventive embodiments performed similarly to inventive embodiment 1, the dry opaque layers on opposite outer and inner sides of the foamed opaque element are printed sequentially. In all embodiments, the quality of the thermally transferred color image was acceptable. No delamination or outgassing was observed for any of the examples.

In addition, as described above, various patterns (images) are similarly thermally transferred (printed) from a suitable thermal donor element to the opposite outer surface of the porous substrate of the foamed opaque element to provide floral, persiley or animal patterns (images), as well as red, flat areas (images) with excellent results.