阅读说明：本技术 涂料组合物和相关纸板结构 (Coating composition and related paperboard structure ) 是由 S·G·布什豪斯 G·P·富吉特 S·E·金瑟 于 2019-01-03 设计创作，主要内容包括：用于纸板的涂料组合物,其包括粘合剂和颜料共混物,所述颜料共混物包括低密度有机颜料和改性无机颜料。(A coating composition for paperboard comprising a binder and a pigment blend comprising a low density organic pigment and a modified inorganic pigment.)

1. A coating composition 10 comprising:

an adhesive 12; and

a pigment blend 14 comprising:

a low-density organic pigment 16; and

a modified inorganic pigment 18.

2. The coating composition 10 of claim 1, wherein the binder 12 comprises a latex.

3. The coating composition 10 of claim 1 or claim 2, wherein the binder 12 comprises starch.

4. The coating composition 10 of any preceding claim, wherein the low density organic pigment 16 comprises hollow spheres.

5. The coating composition 10 of any of the preceding claims, wherein the low density organic pigment 16 has at most 1.04g/cm³The density of (c).

6. The coating composition 10 of any of the preceding claims, wherein the low density organic pigment 16 comprises spheres having an average diameter of about 0.4 μm to about 1.5 μm.

7. The coating composition 10 of any preceding claim, wherein the low density organic pigment 16 comprises at least 15 volume percent of the pigment blend 14.

8. The coating composition 10 of any preceding claim, wherein the modified inorganic pigment 18 comprises a modified clay 22.

9. The coating composition 10 of claim 8, wherein the modified clay 22 comprises delaminated kaolin.

10. The coating composition 10 of claim 8 or claim 9, wherein up to about 25% of the modified clay 22 has a particle size of less than 1 μm.

11. The coating composition 10 of any preceding claim, wherein the modified inorganic pigment 18 comprises a modified calcium carbonate 24.

12. The coating composition 10 of claim 11, wherein the modified calcium carbonate 24 comprises coarse heavy calcium carbonate.

13. The coating composition 10 of claim 11 or claim 12, wherein up to about 12% of the modified calcium carbonate 24 has a particle size of less than 1 μm.

14. The coating composition 10 of any of the preceding claims, wherein the modified inorganic pigment 18 comprises a modified calcium carbonate 24 and a modified clay 22.

15. The coating composition 10 of any one of the preceding claims, wherein the pigment blend 14 further comprises an additional inorganic pigment 20.

16. The coating composition 10 of any one of the preceding claims, wherein the pigment blend 14 has a void volume of at least 40%.

17. A paperboard structure 100 comprising a paperboard substrate 102 and the coating composition 10 of any preceding claim applied to the paperboard substrate 102.

18. A paperboard structure 100 comprising:

a paperboard substrate 102, a base coat 104 and a top coat 106,

wherein the base coat layer 104 is located between the paperboard substrate 102 and the top coat layer 106, and

wherein the basecoat layer 104 comprises a binder 12 and a pigment blend 14, the pigment blend 14 comprising a low density organic pigment 16 and a modified inorganic pigment 18.

19. A paperboard structure 200, comprising:

a paperboard substrate 202 and a single coating 204 applied to the paperboard substrate 202,

wherein the single coating layer 204 comprises a binder 12 and a pigment blend 14, the pigment blend 14 comprising a low density organic pigment 16 and a modified inorganic pigment 18.

20. The paperboard structure 200 of claim 19, wherein the single coating 204 has a dry weight of at most about 9 pounds per 3000 square feet.

Brief Description of Drawings

FIG. 1 is a schematic block diagram of one embodiment of the disclosed coating composition;

FIG. 2 is a graphical representation of the particle size distribution of a commercially available layered clay compared to the particle size distribution of a modified clay suitable for use in the coating composition of FIG. 1;

FIG. 3 is a graphical representation of the particle size distribution of a commercially available crude calcium carbonate as compared to the particle size distribution of a modified calcium carbonate suitable for use in the coating composition of FIG. 1;

FIG. 4 is a cross-sectional view of one (multi-coat) embodiment of a paperboard structure made using the coating composition of FIG. 1;

FIG. 5 is a cross-sectional view of another (single coat) embodiment of a paperboard structure made using the coating composition of FIG. 1;

FIG. 6 is a graphical representation of the amount of low density organic pigment present in the void volume vs of the pigment blend of the disclosed coating composition;

FIG. 7 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. coating weight for a calendered single coat paperboard structure, including two examples and two comparative examples using the disclosed coating compositions formulated with modified clays;

FIG. 8 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. coating weight for a paperboard structure with a basecoat including two examples and two comparative examples using the disclosed coating compositions formulated with modified clays;

FIG. 9 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. base coat weight for an uncalendered topcoat-containing paperboard structure, including two examples and two comparative examples using the disclosed coating compositions formulated with modified clays;

FIG. 10 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. coat weight for a calendered single coated paperboard structure, including two examples and two comparative examples using the disclosed coating compositions formulated with modified calcium carbonate;

FIG. 11 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. coating weight for a paperboard structure containing a basecoat including two examples and two comparative examples using the disclosed coating compositions formulated with modified calcium carbonate; and

FIG. 12 is a graphical representation of Parker Print Surface (PPS10S) smoothness vs. base coat weight for a top coat containing paperboard structure, including two examples and two comparative examples using the disclosed coating compositions formulated with modified calcium carbonate.

Detailed description of the invention

Coating compositions and paperboard structures made using the disclosed coating compositions are disclosed. Various methods are also disclosed.

Referring to FIG. 1, one embodiment of the disclosed coating composition, generally designated 10, includes a binder 12 and a pigment blend 14. The pigment blend 14 includes a low density organic pigment 16, a modified inorganic pigment 18, and optionally, one or more other pigments 20. In one variation, the modified inorganic pigment 18 may be a modified clay 22. In another variation, the modified inorganic pigment 18 may be a modified calcium carbonate 24. In yet another variation, the modified inorganic pigment 18 may include a modified clay 22 and a modified calcium carbonate 24.

A variety of materials may be used as binder 12 of coating composition 10 without departing from the scope of this disclosure. Those skilled in the art will recognize that the composition of adhesive 12 is a design consideration and that the selection of the composition of adhesive 12 is well within the ability of those of ordinary skill in the art.

In a particular embodiment, the binder 12 of the disclosed coating composition 10 may be a latex. A specific non-limiting example of a suitable latex binder is ACRONAL^®S504, a styrene acrylic latex available from BASF Corporation of Florham Park, New Jersey. Another specific, non-limiting example of a suitable latex binder is BASANOL X497AB, a styrene acrylic latex from BASF Corporation.

In another particular embodiment, the binder 12 of the disclosed coating composition 10 may be starch. A specific non-limiting example of a suitable starch binder is ETHYLEX^®2015, Tate available from London, United kingdom&Lyle's ethylated starch.

One skilled in the art will recognize that the amount of binder 12 used in the coating composition 10 is a design consideration, and the selection of an appropriate amount of binder 12 is well within the ability of one of ordinary skill in the art. For example and without limitation, the binder 12 may be present in the coating composition 10 in an amount of about 5 to about 50 parts by weight (e.g., 20 parts) of the binder 12 per 100 parts by weight of the pigment blend 14.

The low density organic pigment 16 of the pigment blend 14 of the disclosed coating composition 10 can be any polymer-based pigment that is hollow (e.g., includes one or more voids) but does not expand more than 10 volume percent upon heating. For example, the low density organic pigments 16 may be hollow spheres formed from a polymeric material, wherein the hollow spheres are sufficiently permeable to air and water vapor such that they do not expand significantly upon heating (i.e., they expand by up to 10% by volume).

Since the low density organic pigment 16 is polymer based and contains voids, the low density organic pigment 16 has a significantly lower density than conventional inorganic pigments such as clay and calcium carbonate. In one expression, the low density organic pigment 16 can have up to 1.04g/cm³The density of (c). In another expression, the low density organic pigment 16 can have a maximum of 0.9 g/cm³The density of (c). In another expression, the low density organic pigment 16 can have a maximum of 0.8 g/cm³The density of (c). In another expression, the low density organic pigment 16 can have a maximum of 0.7 g/cm³The density of (c). In yet another expression, the low density organic pigment 16 can have a maximum of 0.6 g/cm³The density of (c).

Various pigments can be used as the disclosed low density organic pigment 16. As a specific non-limiting example, the low density organic pigment 16 may be ROPAQUE^TMAF-500 EF, which is a low density organic pigment having an average diameter of about 0.4 μm available from the Dow Chemical Company of Midland, Michigan. As another specific, non-limiting example, the low density organic pigment 16 may be ROPAQUE^TMOP-96, which is a low density organic pigment having an average diameter of about 0.6 μm commercially available from The Dow chemical company. As another specific, non-limiting example, the low density organic pigment 16 may be ROPAQUE^TMAF-1055, which is a low density organic pigment having an average diameter of about 1.0 μm commercially available from The Dow Chemical Company. As another specific, non-limiting example, the low density organic pigment 16 may be ROPAQUE^TMAF-1353, which is a low density organic pigment having an average diameter of about 1.3 μm available from The Dow Chemical Company. As yet another specific non-limiting example, the low density organic pigment 16 may be ROPAQUE^TMTH-2000AF, which is a low density organic pigment having an average diameter of about 1.5 μm commercially available from The Dow Chemical Company.

The low density organic pigment 16 may be present in the pigment blend 14 in an amount sufficient to beneficially increase the void volume of the pigment blend 14. In one expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of at least 10 volume percent. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of at least 15 volume percent. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of at least 20 volume percent. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of at least 25 volume percent. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of about 10% to about 80% by volume. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of about 15% to about 65% by volume. In another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of about 20% to about 60% by volume. In yet another expression, the low density organic pigment 16 can be present in the pigment blend 14 at a concentration of about 25% to about 50% by volume.

In addition to the low density organic pigment 16, the pigment blend 14 may further include a modified inorganic pigment 18 and, optionally, one or more other pigments 20. The modified inorganic pigment 18 may include modified clay 22, modified calcium carbonate 24, or various combinations of modified clay 22 and modified calcium carbonate 24. The optional other pigment 20 may be an inorganic pigment (e.g., an unmodified inorganic pigment).

The modified inorganic pigment 18 of the pigment blend 14 of the disclosed coating composition 10 is an inorganic pigment that has been processed or otherwise (e.g., naturally occurring) to have a particle size distribution with a relatively low amount of fine particles (e.g., particles having a particle size of less than 1 μm). That is, the modified inorganic pigment 18 is an inorganic pigment having a controlled amount of particles having a particle size of 1 μm or less.

As used herein, a clay pigment is considered to be "modified clay 22" when at most 30% of the particles of the clay pigment have a particle size of less than 1 μm. In one expression, up to 25% of the particles of the modified clay 22 have a particle size of less than 1 μm. In another expression, up to 20% of the particles of the modified clay 22 have a particle size of less than 1 μm. In another expression, up to 18% of the particles of the modified clay 22 have a particle size of less than 1 μm. In yet another expression, up to 15% of the particles of the modified clay 22 have a particle size of less than 1 μm.

Various clay pigments may be used as is, or processed to produce the modified clay 22. As a general non-limiting example, the modified clay 22 may be kaolin, such as delaminated kaolin. As a specific non-limiting example, the modified clay 22 can be prepared by HYDRAPRINT from KaMin LLC available from Macon, Georgia^®Removing fine particles from kaolin.

FIG. 2 is a graphical representation of a navigation system through a slave HYDRAPRINT^®Modified clay 22 (FIG. 1) from kaolin with fines removed, Standard HYDRAPRINT^®The particle size distribution of the kaolin. Using a SEDIGRAPH available from Micromeritics Instrument Corporation of Norcross, Georgia^®5120A particle size analyzer performs these measurements. The data in fig. 2 is presented as cumulative mass percent less than a given particle size. By identifying the point where the curve intersects 1 μm on the x-axis, one can see the criteria HYDRAPRINT^®The kaolin has approximately 70% particles smaller than 1 μm, while the modified clay 22 has only approximately 8% particles smaller than 1 μm. In addition, HYDRAPRINT^®The kaolin has approximately 83% of particles smaller than 2 μm, and the modified clay 22 has approximately 32% of particles smaller than 2 μm.

Modified clays 22 suitable for use in (or as) the pigment blend 14 of the disclosed coating composition 10 are also disclosed in U.S. ser. number 62/616,094, filed 2018, 1, 11, the entire contents of which are incorporated herein by reference.

As used herein, a calcium carbonate pigment is considered to be "modified calcium carbonate 24" when the particles of the calcium carbonate pigment have a median particle size of about 3 μm to about 8 μm and when at most 15% of the particles of the calcium carbonate pigment have a particle size of less than 1 μm. In one expression, up to 13% of the particles of the modified calcium carbonate 24 have a particle size of less than 1 μm. In another expression, up to 12% of the particles of the modified calcium carbonate 24 have a particle size of less than 1 μm. In another expression, up to 10% of the particles of the modified calcium carbonate 24 have a particle size of less than 1 μm. In yet another expression, up to 8% of the particles of the modified calcium carbonate 24 have a particle size of less than 1 μm.

Various calcium carbonate pigments may be used as such, or processed to produce modified calcium carbonate 24. As a general non-limiting example, the modified calcium carbonate 24 may be ground calcium carbonate. As another general non-limiting example, the modified calcium carbonate 24 may be coarse heavy calcium carbonate. As a specific non-limiting example, the modified calcium carbonate 24 may be prepared by hydrolyzing the HYDROCARB from Omya AG, available from Oftringen, Switzerland ^®60 ground calcium carbonate to remove fine particles.

FIG. 3 is a graphical representation of a slave HYDROCARB ^®60 ground calcium carbonate modified calcium carbonate 24 (FIG. 1) with fines removed compared to standard HYDROCARB ^®60 size distribution of ground calcium carbonate. Using a SEDIGRAPH available from Micromeritics Instrument Corporation of Norcross, Georgia^®5120A particle size analyzer performs these measurements. The data in fig. 3 is presented as cumulative mass percent less than a given particle size. The standard HYDROCARB can be seen by identifying the point where the curve intersects with 1 [ mu ] m on the x-axis^®The 60 heavy calcium carbonate has approximately 39% of particles smaller than 1 μm, while the modified calcium carbonate 24 has only approximately 5% of particles smaller than 1 μm. In addition, HYDROCARB^®The 60 heavy calcium carbonate has approximately 64% of particles smaller than 2 μm, while the modified calcium carbonate 24 has approximately 32% of particles smaller than 2 μm.

Modified calcium carbonate 24 suitable for use in (or as) pigment blend 14 of the disclosed coating composition 10 is also disclosed in U.S. patent No. 8,916,636 issued to Bushhouse et al, 12-23 days 2014, which is incorporated herein by reference in its entirety.

The pigment blend 14 of the disclosed coating composition 10 has a relatively high void volume, particularly compared to the void volume of conventional inorganic pigments and blends of conventional inorganic pigments with organic pigments. In one expression, the pigment blend 14 has a void volume of at least 40%. In another expression, the pigment blend 14 has a void volume of at least 45%. In another expression, the pigment blend 14 has a void volume of at least 50%. In another expression, the pigment blend 14 has a void volume of at least 55%. In yet another expression, the pigment blend 14 has a void volume of at least 60%.

Without being bound to any particular theory, it is presently believed that when the coating composition 10 is applied to a paperboard substrate, the resulting paperboard structure exhibits improved smoothness and surface coverage due to the relatively high void volume of the pigment blend 14. Significantly, such improved smoothness can be achieved without expensive high aspect ratio clay.

Referring to fig. 4, one embodiment of the disclosed paperboard structure, generally designated 100, may include a paperboard substrate 102, a base coat 104, and a top coat 106. Additional coatings may optionally be included between the base coating 104 and the top coating 106 without departing from the scope of the present disclosure. The paperboard substrate 102 may include a first major surface 108 and a second major surface 110. The primer layer 104 may be applied to only the first major surface 108 (C1S) or to both the first major surface 108 and the second major surface 110 (C2S). A topcoat 106 may be applied over the basecoat 104 to present an outermost coating surface 112.

The paperboard substrate 102 of the paperboard structure 100 can be any fibrous material web (web) that can be coated with the disclosed basecoat 14. The paperboard substrate 102 may be bleached or unbleached and may be paper or thicker and stiffer than paper. For example, the paperboard substrate 102 may have about 85 pounds per 3000 ft²Or greater uncoated basis weight. Examples of suitable paperboard substrates 102 include corrugated medium, linerboard, fully bleached kraft board (SBS), and aseptic liquid packaging board.

The basecoat layer 104 of the paperboard structure 100 may be formed by applying the disclosed coating composition 10 (fig. 1) to the first major surface 108 of the paperboard substrate 102.

In a particular embodiment, the basecoat layer 104 may be applied to the first major surface 108 of the paperboard substrate 102 in an amount sufficient to fill pits and cracks in the first major surface 108 without coating the entire first major surface 108 of the paperboard substrate 102, thereby forming a discontinuous film on the first major surface 108. For example, the primer layer 104 may be applied using a blade coater such that the blade coater pushes the primer layer 104 into pits and cracks in the first major surface 108 while removing the primer layer 104 from the first major surface 108. Specifically, the basecoat layer 104 may be applied in a manner similar to plastering, wherein substantially all of the basecoat layer 104 is located in the depressions and cracks of the first major surface 108 of the paperboard substrate 102 rather than on the first major surface 108 of the paperboard substrate 102.

In this regard, those skilled in the art will recognize that when the basecoat layer 104 is used in a blade applicator, the spacing between the moving paperboard substrate 102 and the applicator's blade may be minimized to facilitate filling of pits and crevices in the first major surface 108 without substantially depositing the basecoat layer 104 on the first major surface 108 of the paperboard substrate 102 (i.e., forming a discontinuous film on the first major surface 108 of the paperboard substrate 102). In other words, the blade of the applicator may be placed sufficiently close to the first major surface 108 of the moving paperboard substrate 102 such that the blade of the applicator pushes the basecoat 104 into the pits and cracks in the first major surface 108 of the paperboard substrate 102 while removing excess basecoat 104 from the first major surface 108 of the paperboard substrate 102.

The topcoat 106 may be any suitable topcoat. For example, the top coat 106 may include calcium carbonate, clay, and various other components and may be applied as a slurry over the base coat 104. Topcoats are well known to those skilled in the art and any conventional or non-conventional topcoat composition may be used without departing from the scope of the present disclosure.

The outermost coating surface 112 of the disclosed paperboard structure 100 can be relatively smooth. In one implementation, the outermost coating Surface 112 of the disclosed paperboard structure 100 can have a Parker Print Surface (PPS10S) smoothness of up to about 5 microns. In another implementation, the outermost coating Surface 112 of the disclosed paperboard structure 100 can have a Parker Print Surface (PPS10S) smoothness of up to about 4 microns. In another implementation, the outermost coating Surface 112 of the disclosed paperboard structure 100 may have a Parker Print Surface (PPS10S) smoothness of up to about 3 microns. In another implementation, the outermost coating Surface 112 of the disclosed paperboard structure 100 can have a Parker Print Surface (PPS10S) smoothness of up to about 2 microns.

Referring to fig. 5, another embodiment of the disclosed paperboard structure, generally designated 200, may include a paperboard substrate 202 and a single coating 204 applied to the paperboard substrate 202. The paperboard substrate 202 may include a first major surface 206 and a second major surface 208. The single coating 204 may be applied to only the first major surface 206 (C1S), as shown in fig. 5, or to both the first and second major surfaces 206, 208 (C2S) (not shown). Thus, the single coating 204 may directly contact the paperboard substrate 202 (e.g., the first major surface 206 of the paperboard substrate 202) while also forming the outermost coating surface 210 of the paperboard structure 200.

The paperboard substrate 202 of the paperboard structure 200 can be any web of fibrous material that can be coated with a single coating 204. The paperboard substrate 202 may be bleached or unbleached and may be paper or thicker and stiffer than paper. For example, the paperboard substrate 202 may have about 85 pounds per 3000 ft²Or greater uncoated basis weight. Examples of suitable paperboard substrates 202 include corrugated medium, linerboard, fully bleached kraft board (SBS), and aseptic liquid packaging board.

The monocoat layer 204 of the paperboard structure 200 can be formed by applying the disclosed coating composition 10 (fig. 1) to a first major surface 206 of a paperboard substrate 202.

The outermost coating surface 210 of the disclosed paperboard structure 200 can be relatively smooth, which is difficult to achieve with a single coating. In one implementation, the outermost coating Surface 210 of the disclosed paperboard structure 200 can have a Parker Print Surface (PPS10S) smoothness of up to about 5 microns. In another implementation, the outermost coating Surface 210 of the disclosed paperboard structure 200 can have a Parker Print Surface (PPS10S) smoothness of up to about 4 microns. In another implementation, the outermost coating Surface 210 of the disclosed paperboard structure 200 can have a Parker Print Surface (PPS10S) smoothness of up to about 3 microns. In another implementation, the outermost coating Surface 210 of the disclosed paperboard structure 200 can have a Parker Print Surface (PPS10S) smoothness of up to about 2 microns.

The single coat 204 of the disclosed paperboard structure 200 can have a relatively low dry weight while still providing the desired smoothness. In one expression, the single coating 204 can have up to about 10 lb/3000 ft²Dry weight of (d). In another expression, the single coating 204 can have a maximum of about 9 lb/3000 ft²Dry weight of (d). In yet another expression, the single coating 204 can have a maximum of about 8 lb/3000 ft²Dry weight of (d).

Examples