WO2019226582A1 - Pigment and coating compositions - Google Patents

Abstract

Compositions useful for coating applications, including coating of paper for printing, are described. The composition may include a phyllosilicate mineral, such as kaolin, and a non-ionic dispersant. The composition also may also include other minerals, such as, e.g., calcium carbonate, and/or may include a multivalent metal salt or cationic polymer.

Description

PIGMENT AND COATING COMPOSITIONS

CLAIM FOR PRIORITY

[0001] This PCT International Application claims the benefit of priority of U.S.

Provisional Patent Application No. 62/674,178, filed May 21, 2018, the subject matter of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments of the present disclosure relate generally to compositions useful in pigments and coatings, and methods of making and using such compositions. In particular, the disclosed compositions may be suitable for coating a substrate used in printing.

BACKGROUND

[0003] In printing (such as, e.g., inkjet printing), the substrate (e.g., paper) used plays a role in the quality of the image printed. Papers suitable for inkjet printing usually comprise a basepaper coated with a composition that improves the properties of the paper that are relevant for inkjet printing (e.g., ink reception). The coating composition applied to the paper should be sufficiently capable of absorbing ink (coated on the paper surface) such that the ink appears as a well-focused symmetrical dot on the paper. If the ink is absorbed too deeply into the paper, optical density will be lost, and the ink may spread out in an irregular manner to cover a larger area than intended and appear rough at the edges. Achieving an acceptable combination of properties in a coating composition is not straight-forward, and there is a continued need for improved pigment and coating compositions that are suitable for coating paper used in inkjet printing. SUMMARY OF THE DISCLOSURE

[0004] The present disclosure includes compositions useful for coating substrates, e.g., for printing processes. For example, the present disclosure includes a composition comprising a phyllosilicate mineral and a non-ionic dispersant, wherein the non-ionic dispersant comprises a water soluble polyether polycarboxylate copolymer. The composition may further comprise an additional dispersant such as, e.g., polyacrylate, a polyphosphate, sodium hexametaphosphate, tetrasodium polyphosphate, sodium tripolyphosphate, sodium silicate, or a combination thereof. The weight ratio of the additional dispersant to the nonionic dispersant may range from about 10:1 to about 1:1, for example. In some examples herein, the phyllosilicate mineral comprises kaolin, talc, mica, or a combination thereof such as, e.g., hydrous kaolin, metakaolin, calcined kaolin, or a mixture thereof. The particle size distribution of the phyllosilicate mineral may have a dso diameter ranging from about 0.1 mm to about 2.0 mm, for example.

[0005] According to some aspects of the present disclosure, the dispersant comprises a copolymer of an acrylic acid monomer and a polyalkylene glycol monomer. For example, the polyalkylene glycol monomer has the formula wherein R is a

polymerizable group chosen from methacrylate or methacrylurethane; EO represents ethylene oxide; PO represents propylene oxide; m and n are each integers between 0 and 100, at least one of m or n being non-zero; and R' is hydrogen or an alkyl group comprising 1 to 4 carbon atoms. The acrylic acid monomer may comprise acrylic acid or methacrylic acid, and/or the copolymer may comprise from about 5% to about 40% by weight of the acrylic acid monomer, and from about 60% to about 95% by weight of the polyalkylene glycol monomer. [0006] In some examples, the composition is in the form of an aqueous slurry. The aqueous slurry may, in some cases, have a total solids content ranging from about 40% to about 70% by weight. Additionally or alternatively, the composition may have a Brookfield viscosity less than 600 cP when measured at 20 rmm and 25°C and/or a Brookfield viscosity less than 8000 cP when measured at 20 rmm and 25°C. The composition may further comprise a multivalent metal salt or a cationic polymer, e.g., the multivalent metal salt optionally comprising calcium, magnesium, chloride, sulfate, nitrate, hydroxide, or a combination thereof. In some examples, the multivalent metal salt comprises calcium chloride or calcium sulfate. In some examples, the composition comprises a multivalent metal salt and has a Brookfield viscosity less than 8000 cP when measured at 20 rpm and

25°C.

[0007] The composition may further comprise calcium carbonate and/or a binder (such as, e.g., latex, starch, a starch derivative, polyvinyl alcohol, a protein, or a combination thereof) and/or titanium dioxide, a plastic pigment, or any combination thereof. Additionally or alternatively, the composition may further comprise at least one agent chosen from a cross linker, a water retention aid, a viscosity modifier, a viscosity thickener, a defoaming agent, an optical brightening agent, a dye, a biocide agent, a levelling aid, a grease and oil resistance additive, or a combination thereof.

[0008] The present disclosure also includes paper products (e.g., inkjet printer paper or paperboard) at least partially coated with one or more of the compositions described above or elsewhere herein. One or both sides of the paper products may be coated. BRIEF DESCRIPTION OF DRAWINGS

[0009] Embodiments and various aspects of the present disclosure are illustrated in the following detailed description and the accompanying figures.

[0010] FIG. 1 shows measured viscosity of exemplary compositions discussed in

Example 1.

DETAILED DESCRIPTION

[0011] Particular aspects of the present disclosure are described in greater detail below. The terms and definitions provided herein control, if in conflict with terms and/or definitions incorporated by reference.

[0012] As used herein, the terms“comprises,”“comprising,” or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, composition, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, composition, article, or apparatus. The term“exemplary” is used in the sense of“example” rather than“ideal.” As used herein, the singular forms“a, » U an,” and

“the” include plural reference unless the context dictates otherwise. And, relative terms such as“about,”“substantially,”“approximately,” etc., refer to being nearly the same as a referenced number or value, and should be understood to encompass a possible variation of

±5% or ±2% or ±1% of a specified amount or value.

[0013] The present disclosure describes compositions that may comprise at least one inorganic particulate material, such as a phyllosilicate mineral, and at least one dispersant, such as a non-ionic dispersant. In some examples herein, the composition may further comprise, e.g., one or more of water, a multivalent metal salt, a cationic polymer, a binder, other minerals such as talc, mica, and/or calcium carbonate, and/or one or more additives or agents useful for pigment or coating compositions. For example, in some cases, the compositions herein may comprise one or more other materials, such as a thickener.

[0014] According to some aspects of the present disclosure, the inorganic particulate material may be present in the composition in an amount ranging from about 1 wt % to about

99 wt %, or about 20 wt % to about 95 wt %, or about 45 wt % to about 95 wt % relative to the total weight of dry inorganic particulate material.

[0015] In general, the inorganic particulate material may include one or more phyllosilicate minerals. Exemplary phyllosilicate minerals suitable for the compositions herein include, but are not limited to, a hydrous kaolinitic clay (such as, e.g., kaolin clay or ball clay), an anhydrous (calcined) kaolinitic clay (such as, e.g., metakaolin or fully calcined kaolin), talc, and/or mica.

[0016] According to some aspects of the present disclosure, the phyllosilicate mineral(s) may comprise a kaolin clay derived from a natural source (such as, for e.g., raw natural kaolin clay mineral) using processes (bleaching, refining, grinding/milling, etc.) which are well known to those skilled in the art. Kaolin clay typically comprises at least 50% by weight kaolinite. Kaolinite is an aluminum silicate having a layered structure with the chemical formula of formed from a tetrahedral sheet of silica (S1O4) and an

octahedral sheet of alumina linked together through oxygen atoms. The 1:1 layers are

held together by hydrogen bonding and can typically withstand grinding without fully delaminating. In some examples, the composition may comprise kaolin that includes greater than about 75% by weight, greater than about 90% by weight, or greater than about 95% by weight of kaolinite. The kaolin may be hydrous or at least partially anhydrous or calcined, such as, e.g., metakaolin or calcined kaolin. For example, the phyllosilicate mineral of the composition may comprise hydrous kaolin, metakaolin, calcined kaolin, or a combination thereof. In some examples, the inorganic particulate material may be 100 wt % kaolin (e.g., hydrous kaolin, metakaolin, calcined kaolin, or a combination thereof), or may consist essentially of, kaolin.

[0017] According to some aspects of the present disclosure, the kaolin may be a platy kaolin or a hyper-platy kaolin.“Platy” kaolin refers to kaolin having a higher shape factor, such as a shape factor greater than about 20.“Hyper-platy” kaolin refers to kaolin having a shape factor greater than about 60, e.g., shape factor values ranging from about 60 to about 100 or greater than 100.“Shape factor,” as used herein, is a measure of the ratio of particle diameter to particle thickness for a population of particles of varying sizes and shapes as measured using electrical conductivity methods, apparatuses, and equations as described in U.S. Pat, No. 5,576,617, which is incorporated herein by reference in its entirety. In some examples, the composition may comprise from about 1 wt% to about 99 wt% platy and/or hyper-play kaolin, based on the total weight of the dry inorganic particulate material.

[0018] In some examples, the amount of kaolin in the composition may be up to about 100 wt % based on the total dry weight of the inorganic particulate material. For example, the composition may comprise from about 5 wt% to about 99 wt%, from about 10 wt% to about 90 wt%, from about 25 wt% to about 80 wt %, from about 50 wt % to about 99 wt%, from about 80 wt% to about 95 wt%, from about 60 wt% to about 80 wt%, or from about 40 wt% to about 80 wt% kaolin, based on the total dry weight of the inorganic particulate material. [0019] It is also contemplated that, in some embodiments, the inorganic particulate material of the current disclosure may also include an alkaline earth metal carbonate or sulfate (such as, for e.g., calcium carbonate, magnesium carbonate, dolomite, gypsum, etc.), For example, the inorganic particulate material may comprise ground calcium carbonate (GCC) and/or precipitated calcium carbonate (PCC). In some embodiments, the composition comprises a blend or a mixture of two or more minerals, such as, e.g., kaolin in combination with one or more other minerals. In at least one example, the composition comprises a blend of kaolin and calcium carbonate, such as a blend of 10:90 by weight, 20:80 by weight, 30:70 by weight, 50:50 by weight, 60:40 by weight, 70:30 by weight, 80:20 by weight, or 90:10 by weight of GCC to kaolin. In some examples herein, the composition comprises kaolin and does not include GCC (e.g., the sole pigment is kaolin).

[0020] Some or all the constituents of the inorganic particulate material may be ground to achieve a desired particle size distribution. In some examples, the inorganic particulate material may be ground in an aqueous suspension or slurry, e.g., with a dispersant (e.g., an anionic dispersant or a non-ionic dispersant). Exemplary dispersants useful for grinding include, but are not limited to, polyacrylates, polyphosphates, sodium

hexametaphosphate, tetrasodium polyphosphate, sodium tripolyphosphate, and sodium silicates. The dispersant may improve the wetting of the inorganic particulate material and/or reduce the grinding time.

[0021] All of part of the inorganic particulate material (e.g., kaolin, mica, talc, and/or calcium carbonate) may be classified by a particle size classification procedure to obtain particles having a desired median particle size (e.g., a desired dso value). The median particle size and/or particle size distribution of the inorganic particulate material may be measured in any manner, such as, for example, using a Sedigraph 5100 machine (supplied by

Micromeritics Instruments Corporation, Norcross, Ga., USA). The Sedigraph 5100 machine plots the cumulative percentage by weight of particles having a size (referred to in the art as the equivalent spherical diameter (or ESD)) less than a given ESD value. As used herein, the d₅₀ value refers to the ESD value at which there are 50% by weight of the particles having an equivalent spherical diameter less than the dso value.

[0022] According to some aspects of the present disclosure, the particle size (e.g., the dso value) of the inorganic particulate material may range from about 0.1 mm to about 5 mm or from about 0.1 mm to about 2 mm, such as from about 0.3 mm to about 3.5 mm, from about

0.5mm to about 3.0 mm, from about 1.0 mm to about 2.5mm , from about 0.5mm to about 2.0 mm, from about 1.5 mm to about 5.0 mm, from about 2.0 mm to about 3.0 mm, from about 0.1 mm to about 1.0 mm, or from about 0.3 mm to about 0.7 mm. For example, the compositions herein may comprise kaolin having a dso value ranging from about 0.1 mm to about 5 mm, from about 0.1 mm to about 2.0 mm, from about 0.3 mm to about 3.5 mm, from about 0.3 mm to about 2.0 mm, from about 0.5 mm to about 3.0 mm, from about 0.5mm to about 2.0 mm, from about 1.0mm to about 2.5 mm, from about 0.5 mm to about 2.0mm , from about 1.5 mm to about 5.0 mm, from about 2.0 mm to about 3.0 mm, from about 0.1 mm to about 1.0 mm, or from about 0.3 mm to about 0.7 mm. In at least one example, the dso value of the inorganic particulate material (e.g., kaolin, talc, mica, and/or calcium carbonate) may be less than or equal to about 2.0mm , less than or equal to about 1.0 mm, or less than or equal to about 0.6 mm.

[0023] In some examples, the particulate inorganic material may have a particle size distribution steepness factor equal to or greater than about 25, for example, equal to or greater than about 40, or equal to or greater than about 45, or equal to or greater than about 50. For example, the particulate inorganic material may have a particle size distribution steepness factor ranging from about 25 to about 70, such as from about 45 to about 50, or from about

50 to about 70. The steepness factor is defined as the ratio of the dao value (Sedigraph) (the

ESD at which 30% by weight of the particles are smaller in size) to the dvo value (Sedigraph)

(the ESD at which 70% by weight of the particles are smaller in size), multiplied by 100 (i.e., d3o/d_?o^x100).

[0024] The compositions herein may comprise at least one dispersant, e.g., a nonionic dispersant The compositions herein may comprise, consist of or consist essentially of the particulate inorganic material and the non-ionic dispersant described herein. The non- ionic dispersant may be the same or different than dispersants used during a grinding process.

The dispersant may assist in restricting flocculation of the particulate inorganic material in a slurry or suspension and/or control the viscosity of the composition.

[0025] In general, the amount of the dispersant in the composition may depend upon the application. However, in some embodiments, the amount of the dispersant may be at least about 0.1% by weight of the dry inorganic particulate material (e.g., from about 0.3 wt

% to about 1.5 wt %, for example about 1.25 wt % based on the dry weight of the inorganic particulate material), or at least about 5% by weight relative to the total weight of the composition. In some examples, the amount of non-ionic dispersant in the composition may range from about 0.1 % to about 3.0% by weight, such as from about 1.0% to about 3.0%, from about 2.0% to about 3.0%, from about 0.5% to about 1.5%, from about 0.3% to about

1.5%, from about 0.5% to about 1.0%, or from about 1.5% to about 2.5% by weight of the dry inorganic particulate material. [0026] Water may also be added to the inorganic particulate material before or after mixing it with the dispersant to form an exemplaiy composition of the present disclosure.

The slurry may have a relatively high solids content. For example, the composition may be in the form of a slurry having a solids content of at least about 10 wt %, e.g., ranging from about 10 wt% to about 78 wt%, from about 40 wt% to about 70 wt%, from about 50 wt% to about 60 wt%, from about 40 wt% to about 60 wt%, from about 20 wt% to about 50 wt%, from about 60 wt% to about 70 wt%, In some examples, the slurry may have a solids of at least about 40 wt%, at least about 50 wt %, at least about 60 wt%, or at least about 70 wt%, such as a solids content of about 72 wt%, about 75 wt%, or about 78 wt %.

[0027] In general, any suitable non-ionic dispersant that does not cause the particles (e.g., kaolin particles) to agglomerate in an aqueous medium. Further, for example, the nonionic dispersant may help to distribute the particles in an aqueous medium, e.g., and avoid agglomeration upon the addition of a multivalent salt (e.g., calcium ions from calcium chloride or other calcium salt). Without wishing to be bound by a particular theory, it is believed that non-ionic dispersants may result in a protective colloidal layer around the inorganic particulate material (or pigment(s)) that is sufficiently maintained in the presence of multivalent salt, such that the multivalent salt does not adversely affect the rheology of the composition. The resulting composition, when used to coat a substrate such as paper, may cause the ink to agglomerate and not to penetrate very far into the coating structure on the surface of the substrate. This type of dispersion may be advantageous in connection with high speed coating applications.

[0028] Exemplary non-ionic dispersants that may be used in the compositions herein include, but are not limited to, copolymers of an acrylic acid monomer and a polyalkylene glycol monomer. In some examples, the acrylic acid monomer may comprise acrylic acid or methacrylic acid. Further, for example, the polyalkylene glycol monomer may have the formula where R is a polymerizable organic group, EO is ethylene oxide,

PO is propylene oxide, and m and n are each integers between 0 and 100, at least one of which is non-zero, and R' is hydrogen or an organic group different from R. in at least one example, R is chosen from methacrylate or methacrylurethane, and R' is hydrogen or an alkyl group, e.g., comprising from 1 to 6, from 1 to 5, from 1 to 4, from 1 to 3, 1, or 2 carbon atoms.

[0029] In some examples, the copolymer may comprise from about 5% to about 40% by weight or from about 10% to about 35% by weight of the acrylic acid monomer, and from about 60% to about 95% by weight or from about 65% to about 90% by weight of the polyalkylene glycol monomer. In some examples herein, the non-ionic dispersant comprises hydrosoluble polymers that comprise, or consist, or consist essentially of: (a) from about 5% by weight to about 40% by weight (e.g., from about 5% by weight to about 20% by weight) of methacrylic acid or acrylic acid; and (b) from about 60% by weight to about 95% by weight (e.g,, from about 80% by weight to about 95% by weight) of at least one monomer having the formula R-(EO)_m-(PO)n-R' discussed above.

[0030] The non-ionic dispersants may be formulated based on the above-described composition, or a suitable commercially available non-ionic dispersant may be used.

Commercially available non-ionic dispersants that may be used may include, but are not limited to, Topsperse™ JX A (Coatex), EnviroGem® 2010 (Air Products), DISPERBYK-

2010 (BYK USA), SOLPLUS™ D540 (from Lubrizol), TERGITOL™ 15-S-9 (Dow

Chemical Co.), or Carbosperse™ K-XP228 (Lubrizol). The non-ionic dispersant, along with an inorganic particulate material that includes kaolin, may provide good rheology properties to the compositions herein, combined with good print quality when used to coat a substrate.

[0031] In addition to the presence of the non-ionic dispersants discussed above, the composition may optionally also include one or more other additional dispersants, such as, for example, ionic dispersants (e.g., anionic and/or cationic dispersants). The ionic dispersant(s) may include, for example, a phosphate containing dispersant and/or a polyacrylate (e.g., sodium polyacrylate, ammonium polyacrylate, etc.). In some

embodiments, the additional dispersant(s) may include one or more of polyacrylates, polyphosphates, sodium hexametaphosphate, tetrasodium polyphosphate, sodium

tripolyphosphate, or sodium silicate. In some examples, the additional dispersant(s) may be used during grinding of the inorganic particulate material, the additional dispersant(s) being a residue of the grinding process. In some examples, the additional dispersant(s) may be added to the composition, independent of any dispersant used during grinding. According to some aspects of the present disclosure, the additional dispersant(s) may assist in stabilizing the composition. The amount of additional dispersant(s), when present, may ranging from about

0.3 % by weight to about 5.0 % by weight based on the dry weight of the inorganic particulate material, such as from about 0.5% by weight to about 3.0% by weight, or from about 1.0% by weight to about 2.0% by weight. The amounts of dispersant are expressed as the weight % of active content of the dispersant

[0032] In some examples herein, the composition may comprise a non-ionic dispersant (e.g,, having the formula

as discussed above) and at least one ionic dispersant (e.g., anionic dispersant), wherein the weight ration of the additional dispersant to the non-ionic dispersant ranging from about 10: 1 to about 1:1, from about 7: 1 to about 1 : 1, from about 5: 1 to about 1 : 1, from about 3: 1 to about 1 : 1, or from about 2: 1 to about 1:1.

[0033] As mentioned above, in some examples, the composition may further comprise a multivalent metal salt. For example, the composition may be prepared by combining the inorganic particulate material (e.g., kaolin, or kaolin and calcium carbonate, among other possible combinations of minerals) with a non-ionic dispersant, e.g., to form a slurry, and further adding a multivalent metal salt, with or without the addition or presence of an ionic dispersant or in the substantial absence of an ionic dispersant. The multivalent metal salt may be water soluble. Exemplary multivalent metal salts include, but are not limited to, alkaline earth metal salts, such as, for example, a calcium or magnesium or barium salt (or a combination thereof). Suitable anions of the metal salt include chloride, sulfate, nitrate, and/or hydroxide.

[0034] In some examples, the multivalent metal salt may comprise (or consist essentially of, or consist of) calcium chloride, magnesium chloride, and/or calcium hydroxide. In some embodiments, the metal salts may be provided in hydrated form (such as,

MX2 2H2O, wherein M is a metal and X is an anion, e.g. CaCh ^IfcO). The metal salts may also be provided in anhydrous form. In some examples, the multivalent metal salts may comprise (or consist essentially of, or consist of) calcium sulfate, for example gypsum (calcium sulfate dihydrate), calcium sulfate hemi hydrate, or calcium sulfate anhydrate, for example phosphate derivatives of calcium sulfate anhydrate.

[0035] In general, the amount of multivalent metal salt in the coating composition may be equal to or greater than about 0.01 % by weight, or equal to or greater than about 0.05 % by weight, or equal to or greater than about 0.1 % by weight, based on the total dry weight of the coating composition. In some examples, the amount of multivalent metal salt in the composition may be less than or equal to about 25 % by weight, or less than or equal to about 15 % by weight, or less than or equal to about 12.5 % by weight, or less than or equal to about 5 % by weight, or less than or equal to about 3 % by weight. For example, the amount of multivalent metal salt in the coating composition may be present in an amount of about

0.01 % by weight to about 3 % by weight, for example about 0.05 % by weight to about 3 % by weight, for example about 1 % by weight to about 3 % by weight.

[0036] In addition to a multivalent metal salt, or as an alternative, the composition may comprise a cationic polymer. For example, the composition may be prepared by combining the inorganic particulate material (e.g., kaolin, or kaolin and calcium carbonate, among other possible combinations of minerals) with a non-ionic dispersant, e.g., to form a slurry, and further adding the cationic polymer(s), with or without the addition or presence of an ionic dispersant or in the substantial absence of an ionic dispersant Exemplary cationic polymers suitable for the compositions herein include, but are not limited to

polydiallyldimethylammonium chloride (polyDADMAC), polyethyleneamine,

polyethyleneimine, polyamine polymers, polyimine polymers, and cationic polymeric starches.

[0037] In some examples, the pH of the composition may be adjusted, for example, by adding a base (e.g., sodium hydroxide), an acid, and/or a buffer. In some examples herein, the pH of the composition may be adjusted to be within a range of about 4.0 to about 9.0 or from about 6.5 to about 8.0, such as from about 4.5 to about 8.5, from about 5.0 to about 8.0, from about 6.8 to about 7.8, from about 7.0 to about 7.5, or from about 7.2 to about 7.5, e.g., a pH of at least about 7.0 or ranging from about 7.0 to about 8.0. The pH of the composition may be at least partially determined by the type of binder used and/or other components of the composition.

[0038] The compositions herein may comprise one or more binders. In some examples, the binder(s) may be mixed with the inorganic particulate material using a high speed mixer, e.g., in an aqueous medium, followed by the addition of a multivalent metal salt or cationic polymer. In some examples, the multivalent metal salt or cationic polymer may be added to the inorganic particulate material prior to the addition of the binder(s).

Exemplary binders suitable for the compositions herein include, but are not limited to, latex, starch, starch derivatives, polyvinyl alcohol, proteins, cellulose (e.g., sodium carboxymethyl cellulose), and combinations thereof.

[0039] In some examples, the amount of the binder(s) may range from about 0.5% to about 50% or more by weight of the dry inorganic particulate material, such as, e.g., from about 1% to about 50%, from about 1% to about 25%, from about 5% to about 30%, from about 10% to about 40%, from about 40% to about 50%, from about 15% to about 25%, from about 5% to about 20%, or from about 3% to about 7% by weight of the dry inorganic particulate material.

[0040] The compositions herein optionally may comprise one or more other additives or agents (including pigments), such as, e.g., titanium dioxide, a plastic pigment (e.g., hollow sphere plastic pigments (HSPP)), or a combination thereof. In some examples, the composition may also include one or more of the following: additional pigments, cross linkers, dry or wet pick improvement additives, abrasion resistance additives, water resistance additives, water retention aids, viscosity modifiers and/or thickeners, lubricity/calendering aids, additional dispersants, antifoamers/defoamers, optical brightening agents and/or fluorescent whitening agents, dyes, biocides/spoilage control agents, and/or levelling or evening aids. In cases where pigments such as HSPP are added to provide gloss to the coating, the compositions herein may allow for lower amounts of HSPP to be used to achieve a desired gloss target relative to a composition that does not include kaolin and a non-ionic dispersant as disclosed herein. In some examples, the amount of HSPP may be lowered by an amount ranging from about 10% to about 100%, from about 25% to about 75%, from about

50% to about 80%, or from about 15% to about 45% as compared to a composition that does not include kaolin and a non-ionic dispersant.

[0041] According to some aspects of the present disclosure, the composition may be prepared by combining an aqueous slurry of the inorganic particulate material and the nonionic dispersant, with or without the addition or presence of an ionic dispersant or in the substantial absence of an ionic dispersant. The Brookfield viscosity of such compositions may be less than or equal to 600 cP, such as ranging from about 300 cP to about 600 cP, from about 400 cP to about 550 cP, or from about 500 cP to about 600 cP when measured at a spindle speed of about 20 rpm and at a temperature between about 20 and 30°C (e.g., at 25°C). In some examples, the composition may have a Brookfield viscosity less than 550 cP or less than 500 cP when measured at a spindle speed of about 20 rpm and at a temperature between about 20 and 30°C (e.g., at 25°C). Further, for example, the solids content of the coating composition may range from about 40% to about 70% by weight, or from about 50% to about 65% by weight.

[0042] In some examples, the method additionally comprises adding a binder, a multivalent metal salt, and/or a cationic polymer. The binder, multivalent metal salt, and cationic polymer may be combined with the inorganic particulate material and non-ionic dispersant in any order. For example, the multivalent metal salt may be added to an aqueous composition comprising an inorganic particulate material, a non-ionic dispersant, and a binder. After the addition of a multivalent metal salt, the Brookfield viscosity of such compositions may be less than or equal to about 6000 cP, such as ranging from about 3000 cP to about 6000 cP, from about 4000 cP to about 5500 cP, from about 5000 cP to about 6000 cP, or from about 5250 cP to about 5755 cP when measured at a spindle speed of about 20 rpm and at a temperature between about 20 and 30°C (e.g., at 25°C). For example, the composition may have a Brookfield viscosity less than about 7000 cP, less than about 6000 cP, or less than about 5500 cP when measured at a spindle speed of about 20 rpm and at a temperature between about 20 and 30°C (e.g., at 25°C). Further, for example, the solids content of the composition may range from about 50% to about 70% by weight, from about

50% to about 65% by weight.

[0043] The compositions herein may be applied to a substrate, such as paper (e.g., inkjet printer paper) or other paperboard-related products (e.g., packaging paper) to form a coating. One or more sides of the substrate may be coated. For a paper sheet, for example, one or both sides of the sheet may be coated with a composition as disclosed herein. The compositions herein may provide acceptable properties of brightness (TAPPI T452), opacity

(TAPPI T425), gloss (TAPPI T480), and/or print density (e.g., using a Tobias IQ200 or equivalent color densitometer).

[0044] The coating process may be carried out using any suitable technique. For example, the compositions may be applied by spray coating, curtain coating, blade coating, coating with a roll coater or a gravure coaler, brush coating, dipping, flexo coating, film coating, or rod coating. In some examples, the applied compositions may be dried (e.g., with air and/or heat) to form solid coatings once applied to the substrate. In some cases, the compositions may be applied to the substrate topically.

[0045] According to some aspects of the present disclosure, the process may be performed by a coating machine. Such coating machine may comprise an applicator for applying the compositions described herein to a substrate and optionally a metering device for ensuring that an appropriate level of the composition is applied. Exemplary coating machines may include air knife coaters, blade coaters, rod coaters, bar coaters, multi-head coaters, roll coaters, roll or blade coaters, cast coaters, laboratory coaters, gravure coaters, kisscoaters, liquid application systems, reverse roll coaters, curtain coaters, and spray coaters.

In some examples, the compositions may be applied to a substrate by printing, e.g., offset printing, flexographic printing, or rotogravure printing. Such printing process may allow the compositions to be applied to specified areas on the substrate.

[0046] Aspects of the present disclosure are further illustrated by reference to the following, non-limiting numbered exemplary embodiments.

[0047] 1. A composition comprising a phyllosilicate mineral and a non-ionic dispersant comprising a water soluble polyether polycarboxylate copolymer.

[0048] 2. The composition of paragraph 1, further comprising an additional dispersant different from the non-ionic dispersant.

[0049] 3. The composition of paragraph 2, wherein the additional dispersant comprises a polyacrylate, a polyphosphate, sodium hexametaphosphate, tetrasodium polyphosphate, sodium tripolyphosphate, sodium silicate, or a combination thereof.

[0050] 4. The composition of paragraph 2 or 3, wherein a weight ratio of the additional dispersant to the non-ionic dispersant ranges from about 10:1 to about 1:1. [0051] 5. The composition of any of paragraphs 1-4, wherein the phyllosilicate mineral comprises kaolin, talc, mica, or a combination thereof.

[0052] 6. The composition of any of paragraphs 1-5, wherein the phyllosilicate mineral comprises hydrous kaolin, metakaolin, calcined kaolin, or a mixture thereof.

[0053] 7. The composition of any of paragraphs 1 -6, wherein a particle size distribution of the phyllosilicate mineral has a dso diameter ranging from about 0.1 mm to about 2.0 mm.

[0054] 8. The composition of any of paragraphs 1-7, wherein the dispersant comprises a copolymer of an acrylic acid monomer and a polyalkylene glycol monomer.

[0055] 9. The composition of paragraph 8, wherein the polyalkylene glycol monomer has the formula

wherein R is a polymerizable group chosen from methacrylate or methacrylurethane; EO represents ethylene oxide; PO represents propylene oxide; m and n are each integers between 0 and 100, at least one of m or n being non-zero; and R' is hydrogen or an alkyl group comprising 1 to 4 carbon atoms.

[0056] 10. The composition of paragraph 8 or 9, wherein the acrylic acid monomer comprises acrylic acid or methacrylic acid.

[0057] 11. The composition of any of paragraphs 8-10, wherein the copolymer comprises from about 5% to about 40% by weight of the acrylic acid monomer, and from about 60% to about 95% by weight of the polyalkylene glycol monomer.

[0058] 12. The composition of any of paragraphs 1-1 1, wherein the composition is in the form of an aqueous slurry having a total solids content ranging from about 40% to about

70% by weight. [0059] 13. The composition of paragraph 12, wherein the composition has a

Brookfield viscosity less than 600 cP when measured at 20 rpm and 25°C.

[0060] 14. The composition of any of paragraphs 1-13, wherein the composition further comprises a multivalent metal salt or a cationic polymer.

[0061] 15. The composition of paragraph 14, wherein the multivalent metal salt comprises calcium, magnesium, or a combination thereof.

[0062] 16. The composition of paragraph 14 or 15, wherein the multivalent metal salt comprises chloride, sulfate, nitrate, or hydroxide.

[0063] 17. The composition of any of paragraphs 14-16, wherein the multivalent metal salt comprises calcium chloride or calcium sulfate.

[0064] 18. The composition of any of paragraphs 1-17, wherein the composition has a

Brookfield viscosity less than 8000 cP when measured at 20 rpm and 25°C.

[0065] 19. The composition of any of paragraphs 1-18, wherein the composition further comprises calcium carbonate.

[0066] 20. The composition of any of paragraphs 1-19, wherein the composition further comprises a binder.

[0067] 21. The composition of paragraph 20, wherein the binder comprises latex, starch, a starch derivative, polyvinyl alcohol, a protein, or a combination thereof.

[0068] 22. The composition of any of paragraphs 1-21, wherein the composition further comprises titanium dioxide, a plastic pigment, or a combination thereof.

[0069] 23. The composition of any of paragraphs 1-22, further comprising at least one agent chosen from a cross linker, a water retention aid, a viscosity modifier, a viscosity thickener, a defoaming agent, an optical brightening agent, a dye, a biocide agent, a levelling aid, a grease and oil resistance additive, or a combination thereof.

[0070] 24. A paper product at least partially coated with the composition of any of paragraphs 1-23.

[0071] 25. The paper product of paragraph 24, wherein the paper product comprises inkjet printer paper.

[0072] 26. The paper product of paragraph 24 or 25, wherein both sides of the inkjet printer paper are coated with the composition.

[0073] 27. Use of the composition of any of paragraphs 1-23 as a coating for paper in inkjet printing.

[0074] The following examples are intended to illustrate the present disclosure without, however, being limiting in nature. It is understood that the present disclosure encompasses additional embodiments consistent with the foregoing description and following examples.

EXAMPLES

[0075] Example 1

[0076] Exemplary compositions were prepared and evaluated for their suitability for use in paper coating applications. For these studies, three different commercially available non-ionic dispersants were used: Topsperse™ JX A (Coatex), Disperbyk-2010 (BYK), and Carbosperse™ K-XP228 (Lubrizol). Kaolin (fine kaolin clay) and calcium carbonate (coarse

GCC) were obtained from Imerys.

[0077] Compositions A-H were prepared by combining calcium carbonate

(Compositions A-D), or a mixture of calcium carbonate and kaolin (Compositions E-H) with 1 ,2 wt% of dispersant in water. The solids content was recorded, and the pH and Brookfield viscosity values were measured. The Brookfield viscosity was measured at a temperature of about 27°C (using number 2 and number 6 spindles) at several different spindle speeds (20 rpm and 100 rpm). Next, a hydroxyethylated starch binder (PG 290 produced by Penford) and calcium chloride were added. See Table 1 below. The solids content was again recorded, and the pH and Brookfield viscosity values measured. The values measured before and after addition of the binder and calcium chloride are shown in Table 2. The amounts in weight percent listed in Table 1 are relative to the total amount of dry pigment (CaCOs or kaolin + CaCOa), i.e., parts per 100 parts of dry pigment. All pigments whether organic or inorganic added up to 100 parts and other ingredients were then added on this basis.

[0078] Additional compositions were prepared by pre-dispersing kaolin in a slurry.

In particular, Compositions I-N were prepared by adding kaolin to water with 1.2 wt% of a dispersant to make a 50% solids slurry. The kaolin slurry was combined with calcium carbonate; an additional 1.2 wt% of the respective dispersant was added for Compositions J,

L, and N. The solids content was recorded, and the pH and Brookfield viscosity values were measured as described above. Next, a binder (PG 290) and calcium chloride were added.

See Table 3 below. The solids content was again recorded, and the pH and Brookfield viscosity values measured. The values measured before and after addition of the binder and calcium chloride are shown in Table 4. The amounts in weight percent listed in Table 3 are relative to the total amount of dry particulate material (i.e., kaolin + CaCOa).

Table 4

[0079] It should be noted that the compositions with dispersant had lower viscosities than those without dispersant (i.e., Compositions A and E). Further, as shown in Tables 2 and 4, the addition of the calcium salt increased the viscosity of each composition. However, the increase in viscosity observed for some of the compositions was significantly lower than for others. Since a substantial increase in viscosity may result in poor printing characteristics

(e.g., poor runnability of ink), lower viscosity is expected to provide better performance, particularly in inkjet printing.

[0080] FIG. 1 compares the measured viscosity of some of the evaluated coating compositions before and after the addition of calcium chloride. As can be seen in FIG. 1, the increase in viscosity with calcium chloride addition for Composition J (“Sample J” in FIG. 1) (in which the kaolin was pre-dispersed, then mixed with calcium carbonate and dispersant) is comparable to the increase in viscosity for Composition B (“Sample B” in FIG. 1) (in which calcium carbonate was the sole inorganic particulate material, mixed with dispersant).

Further, the viscosity for Composition J was lower than that of Composition F (“Sample F^* in

FIG. 1) (in which kaolin was not pre-dispersed). These results suggest that pre-dispersing kaolin has a significant impact on viscosity of the composition, providing for less increase in viscosity, such that compositions prepared with pre-dispersed kaolin are expected to provide better printing characteristics. For example, these results suggest that the compositions herein may be useful in multi-purpose grades where the paper may be printed with an inkjet or a lithographic offset process. The lower viscosity of the system using pre-dispersed kaolin is expected to exhibit better runnability and achieve improved sheet performance attributions, gloss, and print density, at lower cost.

[0081] It should be noted that although specific embodiments of coating and pigment compositions are described herein. The current disclosure is not limited to these

embodiments. Other aspects and embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the

embodiments disclosed herein. It is intended that the specification and examples therein be considered as exemplary only, with a true scope and spirit of the present disclosure being indicated by the following claims.

Claims

CLAIMS What is claimed is:

1. A composition comprising;

a phyllosilicate mineral; and

a non-ionic dispersant comprising a water soluble polyether polycar boxylate copolymer.

2. The composition of claim 1, further comprising an additional dispersant different from the non-ionic dispersant.

3. The composition of claim 2, wherein the additional dispersant comprises a polyacrylate, a polyphosphate, sodium hexametaphosphate, tetrasodium polyphosphate, sodium tripolyphosphate, sodium silicate, or a combination thereof.

4. The composition of claim 3, wherein a weight ratio of the additional dispersant to the non-ionic dispersant ranges from about 10:1 to about 1:1.

5. The composition of claim 1, wherein the phyllosilicate mineral comprises kaolin, talc, mica, or a combination thereof.

6. The composition of claim 1, wherein the phyllosilicate mineral comprises hydrous kaolin, metakaolin, calcined kaolin, or a mixture thereof.

7. The composition of claim 1, wherein a particle size distribution of the phyllosilicate mineral has a dso diameter ranging from about 0.1 mm to about 2.0 m.m

8. The composition of claim 1, wherein the dispersant comprises a copolymer of an acrylic acid monomer and a polyalkyiene glycol monomer.

9. The composition of claim 8, wherein the polyalkyiene glycol monomer has the formula

wherein:

R is a polymerizable group chosen from methacrylate or methacrylurethane;

EO represents ethylene oxide;

PO represents propylene oxide;

m and n are each integers between 0 and 100, at least one of m or n being non-zero; and

R' is hydrogen or an alkyl group comprising 1 to 4 carbon atoms.

10. The composition of claim 8, wherein the acrylic acid monomer comprises acrylic acid or methacrylic acid.

11. The composition of claim 8, wherein the copolymer comprises from about 5% to about 40% by weight of the acrylic acid monomer, and from about 60% to about 95% by weight of the polyalkyiene glycol monomer.

12. The composition of claim 1, wherein the composition is in the form of an aqueous slurry having a total solids content ranging from about 40% to about 70% by weight.

13. The composition of claim 12, wherein the composition has a Brookfield viscosity less than 600 cP when measured at 20 rpm and 25°C.

14. The composition of claim 1 , wherein the composition further comprises a multivalent metal salt or a cationic polymer.

15. The composition of claim 14, wherein the multivalent metal salt comprises calcium, magnesium, or a combination thereof.

16, The composition of claim 14, wherein the multivalent metal salt comprises chloride, sulfate, nitrate, or hydroxide.

17. The composition of claim 14, wherein the multivalent metal salt comprises calcium chloride or calcium sulfate.

18. The composition of claim 14, wherein the composition has a Brookfield viscosity less than 8000 cP when measured at 20 rpm and 25°C.

19. The composition of claim 1 , wherein the composition further comprises calcium carbonate.

20. The composition of claim 1, wherein the composition further comprises a binder.

21. The composition of claim 20, wherein the binder comprises latex, starch, a starch derivative, polyvinyl alcohol, a protein, or a combination thereof.

22. The composition of claim 1, wherein the composition further comprises titanium dioxide, a plastic pigment, or a combination thereof.

23. The composition of claim 1, further comprising at least one agent chosen from a cross linker, a water retention aid, a viscosity modifier, a viscosity thickener, a defoaming agent, an optical brightening agent, a dye, a biocide agent, a levelling aid, a grease and oil resistance additive, or a combination thereof.

24. A paper product at least partially coated with the composition of claim 14.

25. The paper product of claim 24, wherein the paper product comprises inkjet printer paper.

26. The paper product of claim 25, wherein both sides of the inkjet printer paper are coated with the composition.