阅读说明：本技术 具有包含热致变色材料的层的系统 (System having a layer comprising a thermochromic material ) 是由 唐杰丛 O·卡亚 S·桑卡兰 何涛 于 2019-06-24 设计创作，主要内容包括：提供了一种具有表面(102)的系统(100)。标记(104)被布置在表面上,该标记代表视觉信息。层(106)被设置在标记上。该层由加热元件(103)加热。该层包括热致变色材料,用于在该层的温度超过阈值温度时改变该层在可见波长下的光吸收。该层在(处于或者)高于阈值温度时具有足够的光学透射性,使得标记提供的视觉信息变得可见。(A system (100) having a surface (102) is provided. Indicia (104) are disposed on the surface, the indicia representing visual information. A layer (106) is disposed on the indicia. The layer is heated by a heating element (103). The layer includes a thermochromic material for changing the absorption of light by the layer at visible wavelengths when the temperature of the layer exceeds a threshold temperature. The layer is sufficiently optically transmissive at (at or above) the threshold temperature such that the visual information provided by the indicia becomes visible.)

1. A system (100) comprising:

-a substrate (101) comprising a surface (102);

-a marking (104) arranged on the surface, the marking representing visual information;

-a layer (106) arranged on the marking; and

-a heating element (103) for heating the layer, wherein the layer comprises:

a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature; and

a binder, the binder being at least one of a fluoropolymer and a sol-gel material.

2. The system (100) according to claim 1, wherein the thermochromic material is adapted to change the light absorption of the layer (106) such that the mark (104) is not visible when the threshold temperature is not exceeded, or wherein the thermochromic material is adapted to change the light absorption of the layer such that the mark is partially visible when the threshold temperature is not exceeded.

3. The system (100) according to any one of the preceding claims, wherein the thermochromic material comprises a leuco dye.

4. The system (100) according to any one of the preceding claims, wherein the threshold temperature is between 30 ℃ and 70 ℃.

5. The system (100) according to any one of the preceding claims, wherein the indicia (104) comprises at least one of text characters, symbols, pictorial images, and patterns.

6. The system (100) according to any one of the preceding claims, wherein the marker (104) is arranged directly on the surface (102).

7. The system (100) of claim 6, wherein the indicia (104) and the surface (102) are colored differently relative to one another to provide a visual contrast between the indicia and the surface when the threshold temperature is exceeded.

8. The system (100) according to any one of claims 1 to 5, comprising a base layer (108) arranged between the substrate (101) and the marker (104).

9. The system (100) of claim 8, wherein the indicia (104) and the base layer (108) are colored differently relative to one another to provide a visual contrast between the indicia and the base layer when the threshold temperature is exceeded.

10. The system (100) according to any one of the preceding claims, wherein the heating element (103) is adapted to heat the substrate (101) by direct heat exchange or indirect heat exchange.

11. An apparatus comprising the system (100) as claimed in any one of the preceding claims.

12. The apparatus of claim 11, corresponding to:

-a garment care device taken from any of a steamer (400, 500), a steam iron, a pressurized steam iron or a carpet cleaner; or

-a cooking device, taken from any of a kettle or an oven.

13. A method (600) comprising the steps of:

-providing (620) indicia on a surface of a substrate, the indicia representing visual information;

-disposing (630) a layer on the marking, the layer comprising a thermochromic material adapted to change the light absorption of the layer such that the marking becomes visible when the temperature of the layer exceeds a threshold temperature, wherein the disposing (630) comprises disposing a mixture of a binder composition and the thermochromic material on the marking, the binder composition comprising at least one of a fluoropolymer and a sol for forming a sol-gel material; and

-providing (640) a heating element for heating the layer.

14. The method (600) of claim 13, further comprising the step of providing (610) a base layer on the surface, wherein the step of providing (620) the indicia comprises providing the indicia directly on the base layer.

Technical Field

The invention relates to a system having a layer comprising a thermochromic material.

The present invention may be used with any system or device that includes a heating element.

Background

Various devices, such as garment care products (e.g., steamers or steam irons), have surfaces that are heated by a heating element. The temperature of the surfaces may exceed 100 c and thus become too hot to be safely contacted during use. There is a particular danger after use when the hot surface may have cooled to some extent but not enough to be safely touched. The user or others may not know that the surface is still at an unsafe temperature and may be injured or uncomfortable by contact with the hot surface.

In view of this problem, it has been achieved by using a mark formed from a thermochromic material to provide a visual warning in response to a change in temperature of a surface heated by a heating element when the surface becomes too hot to be safely contacted. The indicia provides information, such as a warning message or symbol, and the color change of the thermochromic material emphasizes or displays the information.

However, this approach is not without difficulties. Forming such marks on a surface often involves a printing process, such as a screen printing process, using a composition comprising thermochromic material particles. In order to convey information (e.g., warnings) as clearly as possible, it is desirable to have a relatively high resolution of the printed indicia.

However, thermochromic pigment particles tend to be relatively large, i.e. relative to the apertures of a conventional screen, which can lead to processing difficulties during printing, such as screen clogging.

This relatively large grain also means that the resolution of the printed indicia and the clarity of the information conveyed by the indicia may be compromised.

US 2006/081639 a1 discloses a cooking appliance that provides a visual indication to a user to indicate that the cooking appliance is at an elevated temperature above room temperature.

US 2004/149720 a1 discloses a method of alerting individuals that the surface of a counter-top grill, rotisserie or mexican tortilla store is too hot to touch. The method uses a thermochromic composition that displays a thermal warning symbol.

US 6,581,309B 1 discloses a temperature indicator for an iron comprising a visual indicator coupled to a heat sensitive element.

WO 2005/099325 a1 discloses a carrier substrate and a thermochromic material for producing a visual change of the visible surface of the carrier substrate upon reaching an activation temperature.

Disclosure of Invention

It is an object of the present invention to propose an improved system and device which avoids or mitigates the above-mentioned problems.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

To this end, according to an aspect of the present invention, there is provided a system comprising:

-a substrate comprising a surface;

-indicia arranged on a surface, the indicia representing visual information;

-a layer arranged on the indicia; and

-a heating element for heating the layer.

The layer comprises a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature. The layer further comprises a binder that is at least one of a fluoropolymer and a sol-gel material.

The present invention is based on the recognition that thermochromic materials can be used to provide a visible response to a change in temperature without the need to form the mark itself from the thermochromic material. Indicia, such as warning messages or symbols, are disposed on the surface. The indicia may be formed in any suitable manner, such as printing. The layer arranged on the marking comprises a thermochromic material such that the layer provides a visual response to a temperature change caused by a heating element heating the layer. The associated change in the visible light (i.e., at a wavelength between 390 and 700 nanometers) absorption of the layer provides a visual response when the threshold temperature is exceeded. This may involve, for example, the layer changing color, or the layer transitioning from colored below a threshold temperature to colorless above the threshold temperature. For example, the layer may become transparent or translucent, i.e. sufficiently optically transmissive in the visible region, to enable the information provided by the indicia to be visually perceived through the layer.

Above the threshold temperature, the information provided by the mark may be visually perceived through the layer. Thus avoiding the need to form (e.g. print) indicia using thermochromic materials.

The adhesive may allow the layer to protect the indicia and the surface beneath the indicia, for example by providing abrasion and/or non-stick properties. Such anti-wear and/or non-stick properties may be particularly useful when the surface is located, for example, on the sole plate of an iron or on the cooking surface of a frying pan.

Preferably, the thermochromic material is adapted to change the light absorption of the layer such that the mark is not visible when the threshold temperature is not exceeded.

Alternatively, the thermochromic material is adapted to change the light absorption of the layer such that the marking is partially visible when the threshold temperature is not exceeded.

In both cases, above the threshold temperature, the information provided by the mark is visible through the layer. Also by masking (e.g., completely masking) the indicia below the threshold temperature, a more pronounced response to temperature changes may be provided, i.e., as a result of switching from being visually imperceptible by the indicia to being visually perceptible through the layer above the threshold temperature.

Preferably, the thermochromic material comprises a leuco dye.

The thermochromic material is adapted to reverse the change in light absorption of the layer when the temperature of the layer is below a threshold temperature, i.e. above the threshold temperature. The thermochromic material may thus enable the layer to repeatedly change to/above and below the threshold temperature in response to the temperature.

Preferably, the threshold temperature is between 30 ℃ and 70 ℃. This temperature range can be used to alert the system user that the temperature of the layer is too high for safe contact. The threshold temperature may be, for example, about 65 ℃. On the other hand, a threshold temperature near the lower end of the range (e.g., near 30℃.) may also allow the layer to signal when another portion of the system in thermal contact with the layer is too hot to safely make contact. In the latter case, parts of the system may be much hotter than the layer itself.

Preferably, the mark includes at least one of a text character, a symbol, a picture image, and a pattern.

For example, the indicia may spell the word "hot" and/or include a suitable metaphorical warning to alert the user that a threshold temperature has been exceeded.

Preferably, the indicia are provided directly on the surface. In other words, there is no other layer between the mark and the surface.

Preferably, the indicia and the surface are differently coloured relative to each other to provide a visual contrast between the indicia and the surface when a threshold temperature is exceeded.

Thus, the user of the system can easily visually perceive the marker when the threshold temperature is exceeded.

Alternatively, the base layer is disposed between the substrate and the mark.

The base layer provides a suitable surface on which indicia, such as printed indicia, may be applied. In this case, the indicia are disposed directly on the base layer.

Preferably, the base layer comprises a pigment and a binder.

For example, the adhesive may be selected so that the indicia is securely attached to the substrate. In this regard, the binder may for example comprise a (cured) sol-gel material and/or a polymer, such as teflon.

Preferably, the indicia and the base layer are colored differently relative to one another to provide a visual contrast between the indicia and the base layer when a threshold temperature is exceeded.

This can be achieved by enabling the pigment of the base layer to form an appropriate degree of contrast with the indicia. In other words, the respective pigments used for the indicia and the substrate may be selected to contrast with each other. In this manner, a visual contrast is provided between the indicia and the base layer when the threshold temperature is exceeded.

Preferably, the substrate is formed of at least one of a metal material, a plastic material, rubber, and ceramic. For example, the material selected for the substrate may depend on the particular application of the system.

Preferably, the heating element is adapted to heat the substrate by direct heat exchange or indirect heat exchange.

Having the heating element in direct heat exchange with the substrate allows the layer to change its light absorption based on the temperature of the heating element itself. This may be advantageous for safety reasons relating to the temperature of the layer.

Indirect heat exchange of the heating element with the substrate allows the layer to change its light absorption based on the temperature of a portion of the system other than the heating element itself. This may be advantageous for safety reasons relating to the temperature of the device implementing the system according to the invention.

According to another aspect of the invention, there is provided an apparatus comprising the system described above.

Preferably, the device corresponds to:

-a garment care device selected from any one of a steam iron, a pressurized steam iron or a carpet cleaner; or

-a cooking device selected from any of a kettle or an oven.

According to another aspect of the present invention, there is provided a method comprising the steps of:

-providing indicia on the substrate surface, the indicia representing visual information;

-providing a layer on the mark, the layer comprising a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature; and

-providing a heating element for heating the layer.

The disposing step includes disposing a mixture of a binder composition and the thermochromic material on the indicia. The adhesive composition comprises at least one of a fluoropolymer and a sol (curable precursor) for forming a sol-gel material.

The adhesive may act as a carrier for the thermochromic material and may further protect the marker from damage, such as abrasion.

Preferably, the method further comprises the step of providing a substrate on the surface, wherein the step of providing the indicia comprises providing the indicia directly on the substrate.

Preferably, the step of providing indicia comprises printing, embossing or spraying indicia on the surface.

These and other aspects of the disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

Embodiments of the invention will be described in more detail, by way of non-limiting examples, with reference to the accompanying drawings, in which:

FIG. 1A shows a cross-sectional view of a portion of a system below a threshold temperature in which a heating element is in direct thermal communication with a substrate, according to an embodiment of the invention;

FIG. 1B shows a cross-section of a portion of a system according to an embodiment of the invention above a threshold temperature;

FIG. 1C illustrates a cross-sectional view of a portion of the system below a threshold temperature with the heating element in indirect heat exchange with the substrate, in accordance with an embodiment of the present invention;

FIGS. 2A and 2B illustrate different zoomed-out views of the system shown in FIGS. 1A and 1B;

FIGS. 3A and 3B illustrate cross-sectional views of a portion of a system according to another embodiment of the invention below and above a threshold temperature, respectively;

FIG. 4 shows a front portion of a garment steamer according to an embodiment of the invention;

FIG. 5 shows a top portion of a garment steamer according to another embodiment of the invention; and

fig. 6 shows a flow chart of a method according to the invention.

Detailed Description

It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems, and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the figures to indicate the same or similar parts.

A system having a surface is provided. Indicia are disposed on the surface, the indicia representing visual information. A layer is disposed over the indicia. The layer is heated by a heating element. The layer includes a thermochromic material for changing the light absorption of the layer at visible wavelengths when the temperature of the layer exceeds a threshold temperature. The layer has sufficient optical transmission at or above a threshold temperature such that the visual information provided by the indicia can be viewed through the layer.

The system itself may be a device or a part of a device, as will be explained in more detail below.

The term "vision" as used herein refers to what a healthy human eye can perceive under daylight conditions, for example, within a distance of 0 to 5 meters or more from the system.

Fig. 1A and 1B schematically depict cross-sections of a system 100 according to an embodiment of the invention. The system 100 includes:

a substrate 101 comprising a surface 102;

-indicia 104 arranged on the surface, the indicia representing visual information;

-a layer 106 arranged on the indicia; and

a heating element 103 for heating the layer,

the layer comprises a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature.

Preferably, the heating element 103 is adapted to heat the substrate 101 by direct heat exchange or indirect heat exchange.

Surface 102 is heated by heating element 103. The heating elements are adapted to heat (by conduction) the substrate 101 by direct heat exchange, for example by direct contact with each other.

FIG. 1C schematically depicts a cross-section of a portion of a system according to an embodiment of the invention. The system of FIG. 1C differs from the system of FIG. 1A in that the heating elements are in indirect heat exchange with the substrate, such as by not being in direct contact with each other (e.g., through an intermediate layer of air as shown or any other element or portion in between). Thus, the heating element is adapted to heat the substrate by indirect heat exchange (by conduction and/or convection).

Any suitable design of the heating element 103 may be used as long as the heating element 103 is capable of supplying heat to the layer 106. The heating element 103 may be, for example, a resistive heating element, and heat generated by the heating element 103 may be transferred to the surface 102 by conduction. The resistive heating element may for example be adapted to heat water in a steam chamber (not shown) to generate steam. In other words, the heating element 103 may also define a steam generator comprising a resistive heating element, for example in an iron, a steamer or the like.

Alternatively, the heating element 103 may heat the surface 102, for example by magnetic induction, provided that the substrate 101 is made of a suitable material (e.g. iron). Such heating element designs are well known per se and will not be described further herein for the sake of brevity only.

Preferably, the substrate 101 is formed of at least one of a metal material, a plastic material, rubber, and ceramic. For example, the material selected for the substrate may depend on the particular application of the system.

Suitable metallic materials may be, for example, metals such as aluminum or iron. Alternatively, the metallic material may be a metal alloy, such as steel.

An example of a suitable plastic material is polypropylene. As will be readily understood by those skilled in the art, the material for the substrate 101 may be selected to withstand the temperature generated by heating by the heating element 103.

Fig. 1A and 1B show only a portion of surface 102 covered by indicia 104. Indicia 104 is disposed on surface 102 and is used to visually convey information to a user of system 100, for example. In particular, the indicia 104 may be a warning indicia or symbol that warns a user or any person that may come into contact with the system 100 that the system 100 is too hot to safely contact.

Preferably, the indicia 104 comprise at least one of text characters, symbols, pictorial images, and patterns.

For example, the indicia 104 may spell the word "hot" and/or include an appropriate metaphorical warning. Thus, the indicia 104 may serve as a warning sign to protect a user of the system 100 from being burned by contact with a hot surface.

Any suitable thickness of the indicia 104 may be considered if the indicia 104 visually contrast sufficiently with the surface 102 and any other layers between the surface 102 and the indicia 104. In the present context, the term "thickness" is intended to refer to the average height 105 of the markings 104, as seen in the cross-sectional views of fig. 1A, 1B, 1C, 2A, 2B, 3A and 3B. The thickness may be in the range of, for example, 1 micron to 50 microns.

Fig. 2A and 2B illustrate the system shown in fig. 1A and 1B, but also illustrate portions of surface 102 not covered by indicia 104. The term "indicia" should be considered to mean that the indicia 104 suitably differs from the surrounding portions of the surface 102 and any other layers that may be present between the surface 102 and the indicia 104. In this regard, the indicia 104 may be colored and/or textured in a manner that contrasts with the color and/or texture of the surface 102 or the other layers (if present). In this manner, a user of the system 100 may perceive the marker 104 when a threshold temperature is exceeded. This comparison is schematically illustrated in fig. 1A, 1B, 1C, 2A and 2B by the marks 104, the marks 104 being represented by solid black areas, and the substrate 101 being represented by solid white areas without any pattern. For the avoidance of doubt, the terms "colour" and "colouring" as used herein are not intended to exclude shades such as black, white, grey, etc. Thus, the color contrast described below may be achieved, for example, by using black pigment for the indicia 104 applied to the substrate 101 comprising white pigment, and vice versa. A number of different color combinations are conceivable.

The indicia 104 may be applied to the surface 102 of the substrate 101 by any suitable means, such as using printing techniques. Because the mark 104 itself does not require any color change in response to temperature changes, the requirement that the mark 104 contain thermochromic materials, i.e., pigments, is eliminated. Thus, in arranging the mark 104 on the surface 102, pigments having a smaller particle size than conventional thermochromic pigments may be used. This may mean that the resulting indicia 104 may have a suitably high resolution in order to clearly convey information, such as warnings, to a user of the system 100. Further, the indicia 104 may be disposed on the surface 102 using a printing process (e.g., a screen printing process), with less risk of handling difficulties (e.g., screen clogging) because relatively small particle size pigments may be used to form the indicia 104.

Preferably, indicia 104 are disposed directly on surface 102. In other words, there are no other layers between the mark 104 and the surface 102.

Although fig. 1A, 1B, 1C, 2A, 2B, 3A, and 3B illustrate indicia 104 disposed directly on surface 102, this should not be considered limiting. The markings 104 may alternatively be provided in the surface 102 (e.g., engraved). It should also be noted that the indicia 104 need not be applied directly to the surface 102 of the substrate 101. Other layers may be located, for example, between surface 102 and indicia 104. An example of this will be described below with reference to fig. 3A and 3B.

Preferably, the indicia 104 and the surface 102 are colored differently relative to one another to provide a visual contrast between the indicia 104 and the surface 102 when a threshold temperature is exceeded.

The indicia 104 may be printed, embossed, sprayed, or spread on the surface 102, for example. Examples of suitable printing methods include screen printing, such as screen printing, ink jet printing, pad printing, and the like. Preferably, the indicia 104 are applied by screen printing to provide high resolution indicia 104. For example, the indicia 104 may include a suitable pigment to provide the necessary contrast with surrounding portions of the surface 102 and any other layers that may be present between the surface 102 and the indicia 104. The pigments may also be selected such that they are thermally stable over the temperature operating range of the system 100. For example, such suitable pigments may include at least one of a black pigment, a red pigment, and a blue pigment.

The pigment contained in the indicia 104 may be transferred to the surface 102, for example, in a printing paste. Such printing pastes can be used, for example, in screen printing processes.

In addition to pigments, the printing paste may also comprise binder precursors, such as polymers or (curable) sol-gel components. In a non-limiting example, the sol-gel component is prepared by pre-hydrolyzing the methylsilicate precursor using one or more of water, an alcohol (e.g., 2-butanol), and an acid (e.g., HCl). This prehydrolysis may be performed, for example, at room temperature for at least one hour before adding the pigment to the sol-gel composition. For example, a filler, such as a gas phase silicate, may be additionally added to the composition. The paste can be mixed thoroughly before printing. Many variations of the above-described paste preparation will be apparent to those skilled in the art.

The printing paste may then be used to form indicia 104 on surface 102, such as by screen printing. In this example, the printing paste is preferably dried and cured, for example between 60 ℃ and 150 ℃, before the layer 106 is placed on the indicia 104.

Layer 106 is disposed on indicia 104. Layer 106 may be in thermal contact with surface 102 such that layer 106 may respond to any increase in the temperature of surface 102, i.e., due to heating element 103 supplying heat to surface 102.

In effect, layer 106 is heated via surface 102 by conduction of thermal energy directly from surface 102 to layer 106. Note that mark 104 does not significantly affect heat transfer from surface 102 to layer 106 (including the portion of the layer overlying the mark).

With any other layers disposed between surface 102 and layer 106, these other layers conduct heat from surface 102 to layer 106.

When the temperature exceeds the threshold temperature, the layer 106 provides the necessary visual response, which reveals or emphasizes the indicia 104 (i.e., the indicia itself and/or visual information of the indicia).

To this end, the layer 106 includes a thermochromic material that causes a change in the light absorption of the layer 106 at visible wavelengths (i.e., wavelengths between 390 and 700 nanometers) when a threshold temperature is exceeded. It is this change that reveals or emphasizes the mark 104. At or above the threshold temperature, indicia 104 is visible through layer 106, thereby enabling information (e.g., a temperature warning message) to be communicated through layer 106 to inform a user of system 100 that a portion of system 100 (e.g., layer 106) may be too hot to safely touch.

Thermochromic materials are well known per se, and any suitable thermochromic material may be used in layer 106. The thermochromic material may reverse the change in light absorption of the layer 106 when the temperature of the layer 106 is below a threshold temperature, i.e. when the threshold temperature is exceeded. Thus, the layer 106 may be cycled in response to temperatures above and below a threshold temperature. Thus, when the surface 102 heats up, the markings 104 (e.g., warning signs) may appear, and when the surface 102 cools to a safe value (e.g., 60 ℃ or less), the markings 104 may disappear.

Both organic and inorganic thermochromic pigments are known and commercially available. The terms "thermochromic material" and "thermochromic pigment" are used interchangeably herein. Inorganic thermochromic pigments include, for example, transition metal compounds, such as transition metal oxides, for example titanium dioxide and iron trioxide, or cadmium-based compounds. Organic thermochromic pigments include leuco dyes.

Preferably, the thermochromic material comprises a leuco dye.

Leuco dyes switch between two chemical forms, which changes the chromophore of the compound and causes a corresponding change in the light absorption of the material. One chemical form may be colorless, i.e., absorb light outside the visible region, and the other may be colored, i.e., absorb light within the visible region. The leuco dye can include, for example, at least one of a spirolactone, a fluoran, a spiropyran, and a fulgide.

The thermochromic pigment may have any suitable particle size, for example in the range of 0.1 to 50 microns, preferably in the range of 0.5 to 10 microns

In one embodiment, the thermochromic material includes a leuco dye. The thermochromic material may, for example, take the form of microcapsules that encapsulate (i.e., encapsulate within) the leuco dye and any other desired ingredients to help the leuco dye perform its color changing function. In this regard, the microcapsules may comprise other components, such as weak acids and solvents, in addition to the leuco dye.

The selection of thermochromic materials may determine the temperature operating range of system 100. For example, some thermochromic materials may lose their thermochromic properties at temperatures in excess of 200 ℃. Thus, the temperature operating range of the system 100 employing such thermochromic materials may be limited to, for example, between 0 ℃ and 100 ℃. On the other hand, thermochromic materials that can withstand temperatures up to 400 ℃ are also known and are therefore not described further here. The use of such high temperature stable thermochromic materials may allow the temperature operating range of system 100 to be correspondingly increased. Some high temperature stable thermochromic materials may be usefully employed in a layer 106 placed on the soleplate, which layer may be exposed to temperatures above 200 ℃.

A suitable operating temperature range for system 100 may be, for example, 20 ℃ to 150 ℃. A maximum operating temperature of 150 c may provide a suitable lifetime for system 100, particularly since the maximum operating temperature of many currently available thermochromic pigments is about 150 c

The selection from among the various thermochromic pigments currently available may be based on a desired threshold temperature of the layer 106 and/or a desired color below and above the threshold temperature. For example, the color of the layer 106 below the threshold temperature may be red, yellow, blue, black, green, orange, violet, or brown due to the inclusion of the thermochromic material.

Preferably, the threshold temperature is between 30 ℃ and 70 ℃.

In this embodiment, the thermochromic material is selected such that the threshold temperature is between 30 ℃ and 70 ℃. This temperature range may be used to alert the user layer 106 of the system 100 that the temperature is too high for safe contact. The threshold temperature may be, for example, about 65 deg.C

A threshold temperature near the upper end of the range, e.g., near 70 c, may be for safety reasons, i.e., to prevent burns from direct contact with layer 106.

On the other hand, a threshold temperature near the lower end of the range (e.g., near 30℃.) may also allow layer 106 to signal when another portion of system 100 in thermal contact with layer 106 is too hot to safely make contact. In the latter case, portions of system 100 may be much hotter than layer 106 itself.

Depending on the particular thermochromic material selected, and in view of the desired visual response of the layer 106, the thermochromic change of the layer 106 may, for example, change from colored to colorless, or vice versa. In one embodiment, the thermochromic material is selected such that the layer 106 becomes transparent or translucent above a threshold temperature and the indicia 104 becomes visible through the layer 106.

Preferably, the thermochromic material is adapted to change the light absorption of the layer 106 such that the mark 104 is not visible when a threshold temperature is not exceeded.

Alternatively, the thermochromic material is adapted to change the light absorption of the layer 106 such that the mark 104 is partially visible when a threshold temperature is not exceeded.

In both cases, the information provided by the marker 104 may be observed through the layer 106 above the threshold temperature. By also masking (e.g., completely masking) the indicia 104 below the threshold temperature, a more pronounced response to temperature changes may be provided, i.e., due to the switch from being visually imperceptible to the indicia 104 to being visually perceived through the layer 106 when the threshold temperature is exceeded.

Layer 106 also includes a binder that is at least one of a fluoropolymer (e.g., teflon) and a (cured) sol-gel material. Such adhesive materials are stable at high temperatures and therefore contribute to the robustness of layer 106 even at such high temperatures.

The fluoropolymer also has particularly useful non-stick properties, for example, when the layer 106 may come into contact with foreign matter that would otherwise stick to the layer 106 during use of the system.

The thermochromic material may thus be dispersed in the binder. The binder comprises a polymer (e.g. teflon) and/or a (cured) sol-gel material. In other words, the polymer or cured sol-gel material can serve as a carrier for the thermochromic pigment and provide abrasion and/or non-stick properties.

In a non-limiting example, layer 106 may be prepared from a layered composition obtained by adding a sol-gel precursor (e.g., methyltrimethoxysilane) and hydrolyzing the mixture with an acid (e.g., HCl). The thermochromic pigment may then be added to the hydrolysis mixture. Subsequent stirring, for example 30 minutes, ensures that the layered composition is suitably homogeneous. Many variations on the preparation of the layered compositions described above will be apparent to those skilled in the art.

Layer 106 may then be formed by applying the layered composition to indicia 104 (and surface 102), such as by coating, painting, spraying, and the like. Specifically, the layered composition may be sprayed onto the indicia 104. After application, the layered composition may be dried, for example, between 60 ℃ and 120 ℃, and then cured at 150 ℃.

It will be apparent to those skilled in the art that the temperature for drying and curing may be selected to avoid causing unnecessary degradation of the thermochromic material. For example, a conventional sol-gel curing temperature, such as 300 ℃, may be incompatible with thermochromic materials, which may lose thermochromic properties at such high temperatures. In this regard, the drying and curing temperature may be at or below the maximum operating temperature of the thermochromic material. For example, curing temperatures between 150 ℃ and 200 ℃ may be used.

Such a sol-gel adhesive may mean that layer 106 is thermally stable and has good scratch and abrasion resistance. Thus, the layer 106, in addition to performing its thermochromic function, may also serve to protect the surface 102 and the indicia 104 from wear. Thus, layer 106 may be particularly suitable for application to a surface 102 such as the sole plate of an iron or a frying pan.

As will be further explained in connection with fig. 5, a sol-gel carrier may not be needed when the surface 102 to which the layer 106 is to be applied tends to be exposed to lower temperatures during normal use than in the case of a soleplate and a frying pan.

For example, in the case of an iron or steamer, the layer 106 may be applied on an area 114 of the plastic shell adjacent to the heated plate 110. Such areas 114 may become heated during use, but are still exposed to a lower temperature than the heated plate 110 itself. In this case, the indicia 104 may be printed by screen printing, stamping, or otherwise transferring ink onto the region 114. For example, the layer 106 may be formed by dispersing a thermochromic pigment in a solvent (e.g., butyl acetate or ethyl acetate) and spraying the dispersion onto the areas 114 on which the indicia 104 are printed.

The thickness of the layer 106 may depend on the light absorption characteristics of the layer 106, in particular the light absorption characteristics of the thermochromic material. When it is desired that the layer 106 completely obscure the mark 104 below the threshold temperature, a suitably high extinction of the thermochromic material, and a sufficiently high concentration of the thermochromic material in the layer 106, may be used. It will be apparent to those skilled in the art that above the threshold temperature the layer 106 must still not absorb light, so that the indicia 104 are not visible through the layer 106 above that temperature. The thickness of layer 106 must also be considered in this regard. A suitable thickness of layer 106 may be, for example, between 1 micron and 50 microns.

Since the indicia 104 is located below the layer 106, in some cases, such as in the case of a relatively thin layer 106, the layer 106 and the indicia 104 may need to have the same color or a substantially similar color. In this case, the indicia 104 may be incorporated into the layer 106 when the temperature is below the threshold temperature and only displayed when the light absorption of the layer 106 changes (e.g., becomes transparent) above the threshold temperature.

Fig. 1A and 2A show layer 106 below a threshold temperature. The light absorption by the layer 106 is such that the layer 106 at least partially obscures the indicia 104 (i.e., the indicia 104 is not visible or is partially visible).

Fig. 1B and 2B show layer 106 above a threshold temperature. The light absorption of layer 106 allows layer 106 to visually perceive indicia 104 through layer 106. Such a change may cause the layer 106 to become transparent or at least translucent so that the indicia 104 may be viewed through the layer 106. In this case, the contrast between the marking 104 and the substrate 101 on which the marking 104 is directly applied means that the marking 104 can be properly perceived by a user of the system 100, as previously described.

In an alternative embodiment to the embodiment shown in fig. 1A-1C, 2A and 2B, the base layer 108 is disposed between the substrate 101 and the indicia 104.

The base layer 108 provides a suitable surface on which to apply, for example, the printed indicia 104. In this case, the indicia 104 are disposed directly on the base layer 108.

Turning to fig. 3A and 3B, the system 100 further includes a base layer 108 disposed between the substrate 101 and the indicia 104.

Preferably, the base layer 108 includes a pigment and a binder.

For example, the adhesive may be selected so that the indicia is securely attached to the substrate. In this regard, the binder may for example comprise a (cured) sol-gel material and/or a polymer, such as teflon.

The mark 104 is suitably distinguishable from the surrounding portions of the base layer 108. In this regard, the indicia 104 may be colored and/or textured in a manner that contrasts with the color and/or texture of the base layer 108. This allows the user of the system 100 to perceive the marker 104 when the threshold temperature is exceeded, which is shown in fig. 3B.

The contrast between the indicia 104 and the base layer 108 is schematically illustrated in fig. 3A and 3B by the indicia 104 being represented by solid black areas and the base layer 108 being represented by cross-hatched areas. The thickness of the base layer 108 is not particularly limited and may be, for example, between 1 micron and 50 microns.

In one embodiment, the base layer 108 may include a pigment and a binder. For example, the binder may include a polymer and/or a cured sol-gel material. In other words, a polymer or cured sol-gel material may be used as a carrier for the pigment of the base layer 108. Alternatively, the base layer 108 may not include pigments, in which case the polymer and/or cured sol-gel material may be used only to provide a suitable surface to which the indicia 104 is directly applied.

In a non-limiting example, the base layer 108 can be prepared from a base layer-forming composition obtained by hydrolyzing a sol-gel precursor (e.g., a metal alkoxide such as methyltrimethoxysilane and tetraethylorthosilicate) with an acid (e.g., maleic acid, HCl). Transparent or translucent fillers may be added, such as silica or alumina particles ranging in size from 10 nanometers to 10 microns. Subsequently, one or more suitable thermally stable pigments may be added. Many variations in the preparation of the above-described base layer-forming compositions will be apparent to those skilled in the art.

The base layer-forming composition may then be applied to the surface 102 of the substrate 101, such as by coating, painting, spraying, and the like. In particular, the base layer-forming composition may be sprayed onto the substrate 101. Prior to application, the substrate 101 may be subjected to a grit blasting pretreatment, for example. After application, the layer forming composition may be dried, for example between 60 ℃ and 120 ℃, and then cured at 150 ℃.

It will be apparent to those skilled in the art that the temperature of drying and curing may be selected so as not to cause undesirable degradation of the pigment that may be contained in the base layer 108. As described above, the indicia 104 and layer 106 may then be applied to the base layer 108.

Preferably, the heating element 103 is adapted to heat the substrate 101 by direct heat exchange (as shown in FIG. 1A) or indirect heat exchange (as shown in FIG. 1C).

According to another aspect of the invention, an apparatus 400, 500 is provided comprising the system 100 described above.

Preferably, the apparatus 400, 500 corresponds to:

a garment care device taken from any of the steamers 400, 500, a steam iron (not shown), a pressurized steam iron (not shown) or a carpet cleaner (not shown); or

A cooking device (not shown) taken from any of a kettle (not shown) or an oven (not shown).

Fig. 4 shows the front of the garment steamer 400 according to an embodiment of the invention, while fig. 5 shows the top of the garment steamer 500 according to another embodiment of the invention.

The garment steamers 400 and 500 include a heated plate 110 for treating garments. The heated plate 110 has holes 112 for allowing steam to exit the garment steamer 400. An area 114 of the plastic housing is located adjacent to the heated plate 110.

In one embodiment, the system 100 is included in the apparatus 400, 500. The heating element 103 may for example be integrated into the device 400, 500.

The apparatus 400, 500 may be, for example, a garment care device or a cooking device having a substrate arranged to be heated by the heating element 103.

The garment care device may be, for example, a steam iron, a pressurized steam iron, or a carpet cleaner. In this case, the base 101 corresponds to a heated plate 110 (i.e. a soleplate) of a steamer, steam iron (not shown) or pressurized steam iron (not shown), or an area 114 of the housing that receives heat from the heating element 103.

The cooking device may be, for example, a kettle or an oven. In this case, the substrate 101 corresponds to a region 114 of the housing that receives heat from the heating element 103.

The top view of fig. 4 shows the garment steamer 400 below a threshold temperature. Layer 106 is visible, but indicia 104 thereunder is not. However, when a threshold temperature is exceeded, the light absorption of the layer 106 changes, in which case the layer 106 becomes transparent or translucent and the marking 104 becomes (partially) visible.

As previously mentioned, the double-headed arrows shown in FIGS. 4 and 5 are intended to indicate reversibility of the color change.

In this case, the indicia 104 spells "hot" to provide the necessary visual warning. This is shown in the respective lower panes of fig. 4 and 5.

In this manner, the garment steamer 400 can alert the user when overheated by the heating plate 110 without safe contact. In the case of the garment steamer 400 shown in fig. 4, sol-gel derived compositions of the type described above may be particularly suitable for each of the indicia 104 and the layer 106 in view of the high temperatures to which the indicia 104 and the layer 106 may be exposed during use.

Fig. 5 shows that the marking 104 and the layer 106 are alternatively or additionally applied to a region 114 of a (plastic) housing of a steamer 500. In this particular example, the region 114 is located away from the heating plate 110. This region 114 may not be directly heated by the heating element 103, but may become heated due to some heat conduction from the heated plate 110 to this adjacent region 114 of the housing.

The area 114 may be used to warn when the temperature of the heated plate 110 exceeds a safe limit, such as by the visual message "hot" of the indicia 104. The threshold temperature of the layer 106 on the area 114 may be lower than the threshold temperature of the layer disposed on the heated plate 110 itself, such that the area 114 may be used to alert a user when the temperature of the heated plate 110 (which may be significantly higher than the temperature of the area 114 during use) contact is unsafe.

In other words, the region 114 may be considered to be indirectly heated by the heating element 103.

As previously described, indicia 104 may be printed by screen printing, stamping, or otherwise transferring ink onto region 114. The layer 106 may be formed by dispersing the thermochromic pigment in a solvent (e.g., butyl acetate or ethyl acetate) and spraying the dispersion onto the area 114 on which the indicia 104 is printed.

According to another aspect of the invention, there is provided a method 600 comprising the steps of:

-providing 620 indicia on the substrate surface, the indicia representing visual information;

-providing 630 a layer on the mark, the layer comprising a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature; and

providing 640 a heating element for heating the layer.

Preferably, the method 600 further comprises the step of providing 610 a base layer on the surface, wherein the step of providing 620 the marking comprises providing the marking directly on the base layer.

Preferably, the step of providing 620 indicia comprises printing, stamping or spraying indicia on the surface.

The disposing 630 step includes disposing a mixture of the adhesive composition and the thermochromic material on the indicia.

Fig. 6 shows a flow chart of a method 600 according to the invention. The method 600 includes the steps of:

-providing 620 indicia on the substrate surface, the indicia representing visual information;

-providing 630 a layer on the mark, the layer comprising a thermochromic material adapted to change the light absorption of the layer such that the mark becomes visible when the temperature of the layer exceeds a threshold temperature; and

providing 640 a heating element for heating the layer.

Step 620 may, for example, comprise printing, embossing, or spraying indicia on the surface, as previously described.

In step 630, the layer is in thermal contact with the surface.

Step 630 includes disposing a mixture of the adhesive composition and the thermochromic material on the indicia. The layer comprises a thermochromic material adapted to change the light absorption of the layer when a threshold temperature is exceeded. Above a threshold temperature visual information is transmitted through the layer.

In step 640, a heating element is provided for heating the layer.

Preferably, the method further comprises the step of providing 610 a base layer on the surface, wherein the step of providing 620 the marking comprises providing the marking directly on the base layer. As previously described, the color and/or texture of the indicia may be contrasted with the base layer such that the indicia may be visually perceived above a threshold temperature.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope.