CN1784458A - Aqueous systems containing additive pre-mixes and processes forming the same - Google Patents

Abstract

The present invention relates to an additive for pigmented aqueous systems comprising a mixture of a cationic polymer and a high surface area anionic inorganic particle, methods for making and using the additive, methods of forming an aqueous paper coating color as well as cellulose matrix coated therewith; and a process for preparing stabilized pre-mixes.

Description

Aqueous system containing additive premix and method for forming the same

This application claims the benefit of US Provisional Application 60/467,802, filed May 2, 2003, and US Provisional Application 60/470,762, filed May 15, 2003, the entire contents of each of which are hereby incorporated by reference.

technical field

In general, the present invention relates to aqueous systems containing additive premixes and methods of forming such aqueous systems, wherein the additives of the aqueous system for coloring include a mixture of cationic polymers and anionic particles, and relate to the formation of aqueous paper coating colors (coating color) and cellulose substrates coated therewith; and methods of preparing stable premixes.

Background technique

Pigmented coatings have been used to improve the optical properties and printability of paper for more than 100 years. Pigments in coatings and the pore spaces they form are known to increase the opacity, brightness, ink absorption and gloss of paper. The smooth surface formed by calendering the coated paper has a higher gloss than a relatively rough uncoated substrate and is easier to print on.

The use of cationic polymers and cationic pigments in paper coating applications is known in the art. For example, articles such as LePoutre, P. "The structure of paper coatings: an update" in Progress in Organic Coating , 17, pp. 89-106 (1989), and Lepoutre, P. et al., Journal of Pulp and Paper Science, 15, #5, pp. 183-185 "The light-scattering efficiency of microvoids in papercoatings and filled papers" describes the use of cationic polymers, amphoteric polymers and latexes containing amphoteric polymers on their surfaces To control the fixation of paint solids and increase the void fraction of the dried paint. These cationic additives interact strongly with the anionic coating colorants, creating a porous structure that scatters light more efficiently and has more exposed pigment surface area than standard paper coatings. Increasing light scattering increases the opacity and brightness of the paint. Increasing the pigment surface area increases ink absorption. However, the problem of pigment shock (formation of gels and hard aggregates) has prevented the commercial use of cationic polymer additives in paper coating applications.

The use of cationic pigments and cationic polymers in papermaking applications has been discussed in numerous articles and patents, for example, U.S. Patent 2,795,545 (Gluesenkamp); U.S. Patent 3,804,656 (Kaliski et al); U.S. Patent 5,718,756 (Mohler); U.S. Patent 4,738,726 ( Pratt); von Raven A., Scritmatter, G., Weigl, J. "Cationic coating colors-a new coating system", TAPPI Journal, December 1998, pp. 141-148; U.S. Patent 4,874,466 (Savino); U.S. Patent 4,964,955 (Lamar); and US Patent 5,169,441 (Lauzon). These articles and patents are limited to the direct addition of cationic polymers, or the treatment of most waterborne pigments with relatively low additions of cationic polymers, followed by high shear mixing, which leads to the formation of lumps.

The present invention provides a related process, and additives used in the process, which can lead to reduced pigment shock, easier application and better suitability for operation, after considering the needs in the industry.

Contents of the invention

The present invention relates to embodiments of pigmented aqueous systems comprising an additive premix comprising cationic polymers and anionic particles (e.g. high surface area, anionically charged inorganic mineral or synthetic particles and/or mixtures thereof ).

The present invention also relates to a method for forming an aqueous system (for example, an aqueous paper coating color), comprising:

(1) mixing anionic particles and cationic polymers; wherein an additive premix is formed,

(2) optionally filtering the additive premix;

(3) optionally adding a stabilizer to the additive premix;

(4) optionally adding the additive premix to the coating starch;

(5) optionally adding an antimicrobial agent to the additive premix; and

(6) Add the additive premix to the aqueous system.

Still further, the present invention includes coating a cellulose substrate according to the method described above, and said coated cellulose substrate, further comprising the steps of:

(7) coating the cellulosic substrate; and

(8) Drying the cellulose substrate.

Still further, the present invention relates to embodiments of methods of preparing stable premixtures comprising:

(a) forming a premix comprising anionic particles and a cationic polymer;

(b) adding a stabilizer to the premix, wherein a stable premix is formed; and

(c) Optionally adding an antimicrobial agent to the stabilized premix.

In addition, the present invention relates to stable premixes produced using the methods described above.

Description of drawings

Figure 1 depicts the relationship between cationic polymer concentration and pigment oscillation.

Figure 2 depicts the relationship between paint viscosity and premix addition concentration.

Figure 3 depicts the relationship between coat weight and opacity.

Figure 4 depicts the relationship between coating weight and brightness.

Figure 5 depicts the relationship between premix addition concentration and opacity.

Figure 6 depicts the relationship between additive concentration and brightness.

Figure 7 depicts the relationship between post dilution agitation time and pigment shock.

Figure 8 depicts the relationship between premix addition and solids fixation.

Detailed ways

All references cited in this specification, especially US patents, are hereby incorporated by reference in their entirety.

Unless otherwise stated, where a numerical range is recited herein, that range is meant to include its endpoints, and all integers and fractions within the range. It is not intended that the scope of the various embodiments of the invention be limited to the specific values recited when defining a range. Furthermore, all ranges stated herein are meant to include not only the specific range described, but also any combination of numerical values subsumed therein.

Embodiments of the present invention may be used in applications requiring cationic modification of pigments for purposes of enhanced post-drying structuring, such as increased void volume. Thus, embodiments of the present invention are suitable for use in industrial applications including, but not limited to, paper coating, paper size press coating, paper wet end pigment retention, adhesives, drilling mud, and the like.

Generally, the present invention relates to aqueous systems comprising a premix of an additive comprising a cationic polymer mixed with anionic particles, forming an aqueous system containing the additive (e.g., an aqueous paper coating colorants) and cellulosic substrates coated therewith; and to a method of preparing a stable premix wherein the anionic particles moderate the interaction between the cationic polymer and the anionic aqueous pigment, and Significantly reduces or eliminates pigment agglomeration.

The term "system" or its derivatives as used herein includes, but is not limited to, paper coatings, pigmented paint mixtures, paper wet-end pigment retention, adhesives, drilling mud, paper sizing pressure coatings, and the like.

As used herein, the term "anionic particle" includes high surface area, anionically charged inorganic mineral particles, and/or high surface area, anionically charged synthetic inorganic particles, and/or mixtures thereof.

As used herein, the term "indirect addition" describes mixing the cationic polymer and the anionic particles to form a premix prior to adding either the cationic polymer or the anionic particles to the aqueous system.

The term "direct addition" as used herein describes the addition of the cationic polymer to the aqueous system so that no premix is formed.

The term "(co)polymer" as used herein includes both homopolymers and copolymers.

The present invention relates to a pigmented aqueous system comprising:

(i) An additive premix comprising a cationic polymer and anionic particles (eg, high surface area, anionically charged inorganic mineral or synthetic particles).

The types of pigments used in the aqueous system and the amounts of each that can be utilized can vary widely, however, these aspects are well known to those skilled in the art.

The amount of premix added to the pigmented aqueous system is preferably in the range of 0.01-2.0 dry parts per 100 parts of pigment, more preferably 0.05-1.0 part per 100 parts of pigment, most preferably 0.1-0.5 part per 100 parts of pigment. However, the amount of premix added can vary depending on the charge density of the polymer.

Typically, the premix has a solids content of from about 5% to about 40%, preferably from 15% to about 30%, based on the total weight of the premix.

Additionally, in making the additive premix, a cationic polymer can be added to the anionic particle solution, wherein the cationic polymer can be added very quickly, resulting in a lower solids solution. However, it is also desirable to add anionic particles to the cationic polymer solution, which results in a high solids solution that can be diluted and stirred prior to use.

The cationic polymers used in the present invention can be linear or branched and should have some degree of water solubility. Water soluble is meant to indicate that the cationic polymer can be dissolved or dispersed in the pigment premix at concentrations effective for use.

Cationic polymers may contain polar mer units such as (meth)acrylamide, acrylonitrile, etc., or less polar nonionic mer units such as lower alkyl esters of (meth)acrylic acid such as (meth)acrylic acid C _1-4 alkyl esters of acrylic acid, as long as this hydrophobicity and this density of less polar mer units do not unduly reduce the water solubility of the cationic polymer at the concentration used.

Typical cationic polymers include those having a weight average molecular weight of from about 5,000 to about 3,000,000 Daltons, preferably from about 10,000 to about 1,000,000 Daltons, more preferably from about 20,000 to about 500,000 Daltons.

Without being bound by theory, it is believed that the effect of cationic polymers generally increases with increasing charge density. The cationic charge density of the cationic polymers of the invention should preferably be relatively high. The charge density of the cationic polymer is preferably from about 0.1 meq/g to about 8 meq/g, more preferably from about 1 meq/g to about 8 meq/g, most preferably from about 2.0 meq/g to about 6.5 meq/g. Charge density can be determined according to those conventional charge titration methods known in the art.

Suitable cationic polymers include those used in water treatment or papermaking applications, including those described in US Patent Nos. 4,753,710; 5,246,548; 5,256,252 and 6,100,322, incorporated herein by reference. For example, representative cationic polymers described in U.S. Pat. No. 5,256,252 include (1) quaternary ammonium salts of N-alkyl substituted aminoalkyl ester (co)polymers of (meth)acrylates, including, for example, poly(di Ethylaminoethylacrylate) acetate, poly(diethylaminoethyl-methacrylate), poly(dimethylaminoethylmethacrylate) (as alkyl chloride quaternary ammonium salt) "DMAEM.MC Q") etc.; (2) quaternary ammonium salts of reaction products of polyamines with, for example, acrylate-type compounds prepared from methyl acrylate and ethylenediamine; (3) (methacryloyloxyethyl) (Co) polymers of trimethylammonium chloride; (4) acrylamide with quaternary ammonium compounds such as acrylamide and diallylmethyl (β-propionamido) ammonium chloride, acrylamide (β-methyl (Co)polymers of acryloyl oxyethyl)trimethylammonium methylsulfate, etc.; (5) Quaternized vinyl lactam-acrylamide (co)polymers; (6) Hydroxyl-containing unsaturated carboxyl quaternary ammonium salts of acid polyesters such as poly-2-hydroxy-3-(methacryloyloxy)propyltrimethylammonium chloride; (7) as styrene-maleic anhydride (co)polymers and (8) quaternized polyamines; (9) amine and polyester quaternized reaction products; (10 ) quaternary ammonium salts of condensation (co)polymers of polyvinylamine and dichloroethane; (11) quaternized condensation products of polyalkylene-polyamines and epoxyhalides; (12) alkylene-polyamines Quaternized condensation products of polyamines with polyfunctional halohydrins, such as (co)polymers of epichlorohydrin/dimethylamine ("EPI-DMA"); (13) alkylene-polyamines and halogenated Quaternized condensation products of alcohols; (14) (co)polymers of quaternized condensations of ammonia and halogenated alcohols; (15) quaternary ammonium salts of polyvinylbenzyltrialkylamines, such as polyvinylbenzyl (16) Quaternary ammonium salts of (co)polymers of vinyl-heterocyclic monomers with ring nitrogen, such as poly(1,2-dimethyl-5-vinylpyridine methylsulfate), poly(2-vinyl-2-imidazolinium chloride), etc.; (17) polydiallyldimethylammonium chloride ("polyDADMAC") polydialkyldi Allyl ammonium salts; (18) (Co)polymers of ethylenically unsaturated acids, their esters and amides with diallyldialkylammonium salts, including poly(acrylic acid-diallyldimethyl chloride ("polyAA-DADMAC-HPA"); (19) polymethacrylamidopropyltrimethylammonium chloride ("polyMAPTAC"); (20) ammonia-dichloroethane quaternary ammonium salts of condensation (co)polymers; and (21) quaternary ammonium salts of epoxy halide (co)polymers, such as polyepichlorohydrin methyl chloride, polyepichlorohydrin methyl sulfate, and the like. Mixtures comprising two or more of the above polymers may also be utilized.

Preferred cationic polymers include (co)polymers of diallyldialkylammonium salts, (co)polymers of diallylamine, (co)polymers of diallylalkylamine, polyethylene (co)polymers of imines, dialkylamines/epichlorohydrin, (co)polymers of polyamines/epichlorohydrin, (co)polymers of polyamides/epichlorohydrin, (co)polymers of polyamidoamines ) polymers, (co)polymers of polyamidoamine/epichlorohydrin, (co)polymers of dialkylaminoalkylacrylamides and methacrylamides and quaternized (co)polymers, dioxane (co)polymers and quaternized (co)polymers of aminoalkyl acrylates and methacrylates. More preferred cationic polymers include (co)polymers of diallyldimethylammonium salt, (co)polymers of polyamine/epichlorohydrin, polyethyleneimine, (co)polymers of dimethylamine/epichlorohydrin Co)polymers and polyamidoamine/epichlorohydrin (co)polymers. Most preferred cationic polymers include (co)polymers of diallyldimethylammonium salt and (co)polymers of dimethylamine/epichlorohydrin. Mixtures comprising two or more of the above polymers may also be utilized.

When the cationic polymer is added to the aqueous system, it is preferably present in the premix at a concentration of less than 2.5%, more preferably 1.5% or less, most preferably 1.0% or less.

In general, the cationic polymers can be prepared according to any conventional method known in the art.

Generally, as noted above, the anionic particles useful in the present invention include high surface area anionically charged inorganic minerals, and/or high surface area anionically charged synthetic inorganic particles, and/or mixtures thereof.

Examples of suitable anionically charged inorganic mineral and synthetic inorganic particles of the invention generally include swelling clays such as, for example, montmorillonite, and silica-based particles (e.g., silica and alumino-silicate-based )particle).

Montmorillonite clays which may be used are well known in the art of paper retention aids and include swelling clays and their synthetic or semi-synthetic equivalents.

Suitable montmorillonites include, but are not limited to, those described in U.S. Patent 4,753,710, described herein and incorporated by reference, and also include, for example, members of the dioctahedral montmorillonite group (e.g., montmorillonite, bentonite, , montmorillinite, beidellite, and nontronite) and members of the trioctahedral group (eg, hectorite and saponite), sepolite, sepialite, and attapulgite.

Suitable bentonites and hectorites are disclosed in U.S. Patents 4,305,781; 4,753,710; 5,501,774; 5,876,563, respectively; Bentonite, or preferably montmorillonite. The bentonites broadly described in U.S. Patent 4,305,781 are suitable. Suitable montmorillonites include Wyoming bentonite or Fuller's earth. These clays can be chemically modified, for example by treating calcium-based bentonite with alkali converted to alkali metal bentonite, or not); and also described in EP 0446205 published in US Patent 5,071,512, which patents are hereby incorporated by reference.

Preferably, the swelling clay is colloidal, ie, has a particle size in the range of about 1 nanometer (1 nanometer) to about 1 micrometer (1 micrometer). Furthermore, it is preferred that the swelling clay has a surface area of at least 50 m ² /g, more preferably a surface area of at least 100 m ² /g, most preferably at least 200 m ² /g. For example, bentonite preferably has a surface area after expansion of at least 400 m ² /g. Typical coated clay and calcium carbonate surface areas are 1-12 m ² /g.

Preferably the swelling clay, most preferably bentonite, has a dry particle size (dry size) of at least 60% below 50 microns, more preferably at least 90% below 100 microns, most preferably at least 98% below 100 microns.

Silica-based particles that may be used in accordance with the present invention include those described in US Pat. Polyaluminosilicate (polyaluminosilicate) and polyaluminosilicate microgels, which are included in the term colloidal aluminum-modified silica and aluminum silicate as used herein), and their mixtures, used alone or Use in combination with other types of anionic inorganic particles and the like for use as retention aids is well known in the art.此外，合适的硅石和硅铝酸盐基颗粒包括公开于美国专利4,388,150；4,954,220；4,961,825；4,927,498；4,980,025；5,127,994；5,176,891；5,368,833；5,447,604；5,470,435；6,100,322；也公开为美国专利5,603,805的EP0656872以及WO 95 /23021, all of which are incorporated herein by reference.

Suitable silica-based particles preferably have a particle size of less than about 50 nanometers, more preferably less than about 20 nanometers, most preferably about 1 to about 10 nanometers. Suitable silica-based particles have a specific surface area of at least 50 m ² /g, preferably at least 100 m ² /g, and preferably at least 200 m ² /g. The specific surface area can be measured by NaOH titration according to the method described by Sears in Analytical Chemistry 28 (1956): 12, 1981-1983.

Mixtures of silica and swelling clays such as montmorillonite, preferably natural sodium bentonite, may also be used in the present invention.

Typically, the ratio of anionic particles to cationic polymer in the additive premix can be from about 95:5 to about 10:80 (about 95% to about 10% by weight anionic particles and about 5% to about 80% by weight cationic polymer), preferably about 90:10 to about 20:80 (about 90% by weight to about 20% by weight of anionic particles and about 10% by weight to about 80% by weight of cationic polymer), more preferably 90:10 to about 40:60 (about 90% to about 40% by weight anionic particles and about 10% to about 60% by weight cationic polymer), most preferably 85:15 to about 60:40 (about 85% to about 60% by weight % of anionic particles and from about 15% to about 40% by weight of cationic polymers). However, this ratio depends on the polymer used, for example, when using a mixture of bentonite and poly-DADMAC, the ratio of bentonite:poly-DADMAC is preferably from about 92.5:7.5 to 60:40, more preferably from about 70:30 to About 85:15 range.

The present invention further relates to forming an aqueous system (for example, an aqueous paper coating colorant) comprising:

(1) mixing anionic particles and cationic polymers; wherein an additive premix is formed,

(2) optionally filtering the additive premix;

(3) optionally adding a stabilizer to the additive premix;

(4) optionally adding the additive premix to the coating slurry;

(5) optionally adding an antimicrobial agent to the additive premix; and

(6) Add the additive premix to the aqueous system.

Still further, the present invention includes coating a cellulose substrate according to the method described above, and said coated substrate, further comprising the steps of:

(7) coating the cellulosic substrate; and

(8) Drying the cellulose substrate (eg, paper).

The additive premix can be added to the waterborne system at any point during the preparation of the coating. Preferably, however, the premix is added to the paint slurry or added last. The paint slurry is a compound of a number of paint components where the premix is added to the paint slurry for the purpose of diluting the premix. The coating slurry typically contains a high percentage of water (eg, about 70% water relative to solids content), enabling dilution of the premix without introducing additional quantities of water to the overall aqueous system. In each case, however, the additive premix was added indirectly, wherein said additive premix was formed prior to addition to the aqueous system as described above. Anionic particles and cationic polymers such as those described above can be used herein.

In general, the order of mixing in step (1) is not critical to performance when non-swelling anionic particles are used, but the anionic particles are usually added "as is" to the polymer solution. However, the order of the steps in the process is important when producing high solids premixes (>5% solids). If a swelling clay (eg bentonite, etc.) is used, it is preferred to add the anionic particles to a quantity of water containing the cationic polymer, rather than adding the swelling clay to the water and then adding the polymer.

As indicated in step (2), the premix may optionally be filtered to remove any formed Coarse, where the filter automatically sweeps the sieve to prevent clogging of the sieve.

Introduction An optional stabilizer may be added to the premix in step (3) to reduce any precipitation or stratification of the anionic particles in the premix. The stabilizer can be of high or medium molecular weight and can be cationic or nonionic. Non-ionic stabilizers include hydroxymethyl hydroxyethyl cellulose, butyl glycidyl ether modified hydroxyethyl cellulose, hydroxypropyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, Methylcellulose, ethylcellulose, poly-N-vinylpyrrolidone, polyvinyl alcohol, polyethylene oxide, polypropylene oxide, polyacrylamide, starch ethers (such as hydroxyethyl starch), starch esters ( Such as alkyl succinic anhydride modified starch), oxidized starch, guar gum, pectin, carrageenan, locust bean gum, xanthan gum, water-soluble proteins (such as soybean) and hydrophobic associative paint enhancers. Thickener. Cationic stabilizers include cationic starch and Galactosol cationic guar gum (Hercules Inc., Wilmington, Delaware). Preferably the stabilizer is non-ionic. Most preferably the stabilizer is hydroxypropyl guar gum or hydroxyethylcellulose.

Typically, the amount of stabilizer used results in an aqueous system having a viscosity of at least 1000 cps (Brookfield at 100 RPM), preferably at least 2000 cps, more preferably at least 3000 cps. Most preferably the viscosity is in the range of about 2000 to about 3500 cps.

Typically, stabilizers are added in an amount of about 0.1% to about 5% based on the total weight of the premix, however, the amount depends on the type of stabilizer and the solids content of the premix. For example, for hydroxyethylcellulose and hydroxypropyl guar, preferably the amount is from about 0.2% to about 1.0%, more preferably from 0.3% to about 0.7%, based on the total weight of the premix. Stabilizer addition rates and agitation are known in the art and should be adjusted to obtain a smooth mixture.

For example, the optional antimicrobial agent in step (5) is often used when it is desired to prevent odor, delamination and lack of storage stability caused by bacteria consuming a particular polymer such as guar gum. Aqueous systems can be prepared without the use of antimicrobial agents, however, refrigeration, vacuum packaging or use for short periods of time are often required due to the adverse effects of bacteria. Examples of suitable antimicrobial agents include, for example, AMA-35D-P antimicrobial agent (Kemira Chemical Co. Marietta, Georgia) and Proxel GXL (Avecia Inc., Wilmington DE).

For step (6), the premix is usually pumped or poured into the aqueous system without any particular limitation on the method or speed of addition. As noted above, it is preferred that the cationic polymer is present in the premix at a concentration of less than 2.5%, more preferably 1.5% or less, most preferably 1.0% or less when added to the aqueous system.

Coating of cellulose substrates can be carried out according to methods known in the art, for example as described in Pigment Coating and Surface Sizing of Paper, Lehtinen, Esa, published by Fapet Oy (2000), pp. 415-594.

Drying of the cellulose substrate can be carried out according to methods known in the art, for example as described in Pigment Coating and Surface Sizing of Paper, Lehtinen, Esa, pp. 415-594, published by Fapet Oy (2000).

The invention further relates to a process for preparing a stable premixture of polymer and anionic particles suitable for use after a shelf life. More specifically, methods for preparing stable anionic particle/polymer premixes and stabilizers include:

(a) forming a premix comprising anionic particles, preferably bentonite, and a cationic polymer;

(b) adding a stabilizer (neutral or cationic) to the premix, wherein a stable premix is formed; and

(c) Optionally adding an antimicrobial agent to the premix.

In addition to those described above, examples of suitable bentonites include, for example, commercially available compositions such as sodium bentonite (Wyoming or Western), which have a high degree of swelling in water.

The cationic polymer component of the present invention may be any cationic polymer conventionally used in the papermaking process, such as those described above. Similarly, the anionic particles and stabilizers described above can also be used herein.

Typically, as stated above, the amount of stabilizer used will result in a viscosity of at least 1000 cps (Brookfield at 100 rpm), preferably at least 2000 cps, more preferably at least 3000 cps. Most preferably the viscosity is in the range of about 2000 to about 3500 cps. In addition, the stabilizer is usually added at about 0.2% to about 5% based on the total weight of the premix, but the amount depends on the kind of stabilizer and the solid content of the premix. For example, for hydroxyethylcellulose and hydroxypropyl guar, preferably the amount is from about 0.2% to about 1.0%, more preferably from 0.3% to about 0.7%, based on the total weight of the premix.

The present invention further relates to stable premixes formed by the methods described above.

Example

In the following examples, the present invention is described in further detail, wherein all parts and percentages are by weight. It should be understood, that these Examples, which represent preferred embodiments of the invention, are given by way of illustration only. From the above discussion and these examples, without departing from the spirit and scope of the present invention, those skilled in the art can ascertain the main features of the present invention, and make various changes and modifications to the present invention, so that it is suitable for various application and conditions.

Example 1 - Preparation of 85:15 Bentonite:poly-DADMAC Premix

A 5% solids 85:15 bentonite:poly-DADMAC premix was prepared using the following procedure. 106.25 g of bentonite (Bentolite H from Southern Clay Products, Gonzalez, Texas) and 2346.88 g of water were charged into a 5 L beaker and mixed using an overhead stirrer for 1-2 minutes until a homogeneous premix was obtained (500 rpm). 46.88 g of PRP-4440 poly-DADMAC (diallyldimethylammonium chloride polymer, 40% solids, available from Pearl River Polymers, Riceboro, Georgia) was then added dropwise over a period of 1-2 minutes. ). During the addition of poly-DADMAC, the mixture swelled and thickened before redispersing. After complete addition, the premix was agitated for an additional 2 hours, sonicated for 10 minutes on Device #2 of a Branson Sonicator 450, then filtered through a 200 mesh screen to remove any coarse particles. If necessary _, adjust the pH of the final premix to pH 7-8 using 15% _H2SO4 .

Example 2 - Preparation of Silica: Reten 203 Premix

Silica at 5% solids was prepared using the following method over the range of proportions shown in Table 1: Reten 203 Cationic Polymer Premix. The required amount of silica (Ludox FM, Grace-Davison, Columbia; Maryland) and water were charged to a 100 mL beaker and mixed using an overhead stirrer (500 rpm) for 15 minutes. The required amount of Reten 203 (diallyldimethylammonium chloride polymer, Mn = 2-300,000, 20% solids, available from Hercules Incorporated, Wilmington , DE). The premix was then stirred for 2.5 hours and sonicated for 3 minutes on a Branson Sonicator 450, Apparatus #8. Strain again through a 200 mesh sieve to remove any coarse particles. Adjust the premix to _pH 7-8 with 15% _H2SO4 if necessary.

Table 1 Final Total Solids % 5 TS% of silica solution 16.02 Final pH 7-8 TS% of Reten solution 20.41 final volume 25 Proportion Silica Reten Silica% g. Silica Reten% g. Reten g. water 100 1 4.95 7.73 0.05 0.06 17.21 100 10 4.55 7.09 0.45 0.56 17.35 100 50 3.33 5.20 1.67 2.04 17.76 100 100 2.50 3.90 2.50 3.06 18.04 50 100 1.67 2.60 3.33 4.08 18.32 10 100 0.45 0.71 4.55 5.57 18.72 1 100 0.05 0.08 4.95 6.06 18.86

The preparation of embodiment 3-kaolin/calcium carbonate paint pigment

A kaolin/calcium carbonate based coating color was prepared using the following procedure. A detailed description of the formulations is given in Table 2. First add the required amount of dilution water and dispersant (Dispex N40V, Ciba Specialty Chemicals, Sufolk VA). Hydrafine(R) #1 kaolin (commercially available from JM Huber Corporation, Edison, NJ) was then added slowly with vigorous stirring using a Cowles mixer. Keep a good swirl throughout the clay addition. After the clay was well dispersed, Hydrocarb® 90 ground calcium carbonate (Omya, available from Pleuss-Staufer Incorporated, VT) and _RPSTiO slurry (available from EI duPont de Nemours and Company, Wilmington, DE) were slowly added with vigorous stirring. . The slurry was then stirred for an additional 30 minutes using a Cowles mixer.

While preparing the pigment slurry, Penford 290 starch (available from Penford Products Co. Cedar Rapids, Iowa) was cooked at 95-100° C. for 45 minutes using a steam jacketed pot. The concentration of starch (30%) was adjusted during cooking to compensate for water loss. The hot starch solution (stored at 65°C) was then added to the pigment slip while stirring vigorously. After the coating had cooled from the starch addition, styrene butadiene latex (Dow 620, Latex CP620NA, Dow U.S.A. Midland, Michigan) was added and mixed thoroughly into the coating color. While stirring vigorously, Calsan® 65 lubricant (BAS F, North Mount Olive, NJ), Sequarez® 755 insolvent (Omnova Solutions Corporation, Fairlawn, OH) and Proxel GXL preservative (Avecia Inc.) were added sequentially. After these additives were dispersed, the pH of the coating color was adjusted to 8.0 with ammonium hydroxide. The coating color was adjusted to 68% solids with water prior to addition of the particle/cationic polymer mixture.

Premixes of bentonite/poly-DADMAC (Example 1) and silica/poly-DADMAC (Example 2) were added to the clay/carbonate coating color using the following procedure. The required amount of particle/cationic polymer premix was added dropwise to the stirred coating color sample (68% solids). Premixes of bentonite and silica were added at 5% of total solids unless otherwise stated. Maintain a good vortex throughout the addition of the pellet premix. The required amount of water was then added to dilute the coating color to 62% total solids unless otherwise stated. The treated samples were stirred for an additional 15-30 minutes (500 rpm) prior to testing.

Table 2 Clay/Carbonate Compound additive describe number of copies dry grams solid% wet grams added #1 Kaolin Hydrafine 58 1740 100% 1740 GCC Hydrocarb 90 41 1230 100% 1230 TiO2 RPS slurry 1 30 71% 42.3 latex Dow 620 9 270 50% 540 starch Penford 290 3 90 30.36% 296.4 lubricant Calsan 65 0.3 9 50% 18 Dispersant Dispedx N-40 0.1 3 40% 7.50 Insoluble adhesive Sequarez 755 0.21 6.3 55% 11 preservative Proxel GXL 0.1 3 100% 3 alkali Ammonium hydroxide as needed total dry grams 3378.3 total wet grams 3885.65 total solids 68% grams added to water 1082.44 final gross weight 4968.09

Example 4 - Bentonite/poly-DADMAC Premix

663 g of water and 108.4 g of PRP-4440 poly-DADMAC (diallyldimethylammonium chloride polymer, 40% solids, Pearl River Polymers, Riceboro, Georgia) were charged into a stainless steel beaker and stirred at 500 rpm for 5 minutes. Then 228.3 g of bentonite (92.7% solids obtained as Bentolite H from Southern Clay Products, Gonzalez, Texas) was mixed in over a period of 5 minutes. After the addition was complete, the premix was stirred at 500 rpm for 2 hours. The temperature of the premix was maintained at 20°C throughout the process. The premix was then filtered through a 200 mesh screen to remove any coarse particles formed by agglomeration of the anionic bentonite and cationic polymer. About 0.5 g of coarse particles were separated by sieve (0.2% of total solids).

After completion of the filtration, 1.2 g of antimicrobial agent (AMA-35D-P antimicrobial agent, Kemira Chemical Co. Marietta, Georgia) and then 6.0 g of hydroxypropyl guar gum (HPG, Galactasol 40H4FD 1-Hercules, Wilmington, Delaware) was sprayed into the premix. The premix was stirred for an additional 3 hours (500 rpm) after the addition was complete. The temperature of the premix was maintained at 20°C throughout the process. The viscosity of the premix increased rapidly within the first 30-60 minutes after the addition of the hydroxypropyl guar gum. The final product had a pH of 7.9 and a Brookfield RV viscosity of 3000 cps (100 rpm, #5 spindle).

Example 5 - Effect of Premix Solids and HPG Addition on Layering

A screening test was performed to determine the highest solids of the bentonite/poly-DADMAC premix, which could be performed using the additional method described in Example 4. As shown in Table 3, fluid premixes were made at up to 40% total solids. The Brookfield RV viscosity of the premix increases (100 rpm) with increasing % solids.

table 3 solid% Brookfield Viscosity twenty one% 34cps twenty four% 42cps 27% 50cps 30% 64cps 35% 120cps 40% 260cps

The effect of HPG on precipitation stability was then measured at 21%, 24%, 27%, and 30% premix solids. The premix was prepared using the method described in Example 4. The amount of HPG added was chosen to produce a premix viscosity in the range of 500 cps to 3500 cps per % solids. Acceptable settling stability is defined as less than 5% solids stratification from the top to the bottom of the premix and no lump formation.

As shown in Table 4, the stability of the premixes generally increased with increasing % solids, amount of HPG added, and viscosity of the premixes. All 16 premixes showed good 1-day precipitation stability. All premixes with an initial viscosity of at least 1500 cps (Brookfield RV, 100 rpm) gave acceptable storage stability of at least 1 week. All premixes with an initial viscosity of less than 1500 cps failed the stability test after 1 week of storage. Also, all premixes with an initial viscosity of at least 3000 cps showed no signs of separation or formation of lumps after 8 weeks of storage. Testing of premixes that passed the 4 and 8 week stability tests showed that when tested with the paint formulation described in Example 3, they gave the expected increase in paint viscosity without pigment shock . The premix was diluted to 5% total solids and stirred for 30 minutes before adding to the coating. The amount of grit remaining on the 200 mesh sieve of a 200 g sample of the treated paint was used as a measure of pigment shock.

Example 6 - Preparation of a stabilized bentonite/poly-DADMAC premix

255 g of bentonite (Bentonite H, available from Southem Clay Products) and 1632.5 g of water were charged into a stainless steel beaker and mixed (500 rpm) with an overhead stirrer for 1-2 minutes. While stirring vigorously, add 112.5 g of PRP-4440 poly-DADMAC (diallyldimethylammonium chloride polymer, 40% solids, available from Pearl River Polymers) dropwise over a period of 1-2 minutes. , Riceboro, GA). During the addition of PRP-4440, the mixture swelled and thickened before redispersing into a fluid premix. Once the addition was complete, the mixture was stirred for an additional 90 minutes and then sonicated on a Branson Sonifier 450, Apparatus #2, for 15 minutes.

A 200 mL aliquot of the cationic bentonite premix was then filled into a glass beaker. 1.0 g of Natrosol 250H4BR (hydroxyethylcellulose, commercially available from Hercules, Wilmington, DE) was slowly added to the premix while stirring vigorously with an overhead stirrer. Once this addition was complete, the mixture was continued to be stirred for 30 minutes, then sonicated using a Branson Sonifier 450 on Apparatus #2 for 6 minutes. After two weeks at room temperature, no sign of precipitation or separation of the premix was observed.

Example 7 - Effect of Premix Dilution on Pigment Shock

Measured at solution concentrations of 0.75% and 2.25% by direct addition of PC-1193 (equivalent to PRP-4440 from Pearl River Polymers, diallyldimethylammonium chloride polymer, hereinafter referred to as PRP-4440) The degree of pigment shock caused by it. These solution concentrations correspond to a 85:15 bentonite:PRP-4440 premix at 5% and 15% total solids, respectively. The bentonite premix was prepared using the method described in Example 6. The evaluation was carried out in the clay/carbonate coating color described in Example 3. The amount of grit remaining on a 200 mesh sieve of a 200 g sample of the treated paint was used as a measure of pigment shock.

As shown in Figure 1, by reducing the concentration of PRP-4440 from 2.25% to 0.75%, the degree of pigment shock in the clay/carbonate coating color was significantly reduced. Reducing the concentration of the 85:15 bentonite:PRP-4440 mixture from 15% (2.25% of PRP-4440) to 5% (0.75% of PRP-4440) of total solids also reduced pigment shock. A comparison of the degree of pigment shock caused by adding PRP-4440 directly at 2.25% solids to an 85:15 mixture of bentonite clay at 15% solids (also 2.25% PRP-4440) showed that premixes containing bentonite PRP-4440 The substance reduces pigment shock by 85-90%. A similar comparison at a solution concentration of 0.75% PRP-4440 and a bentonite mixture concentration of 5% total solids (also 0.75% PRP-4440) showed that premixing PRP-4440 with bentonite reduced pigment shock by 98-99%. The 85:15 bentonite mixture at 5% solids gave similar pigment shock to the untreated paint control.

Example 8 - Effect of Bentonite/poly-DADMAC Dilution on Coating Viscosity

85:15 bentonite:PRP-4440 premixes with total solids concentrations ranging from 2.5% to 20% were prepared by diluting the 25% solids premix prepared by the method described in Example 4. The effect of each premix on the viscosity of the kaolin/calcium carbonate coating formulation Brookfield described in Example 3 was then tested. Premix additions in the range of 0.35-0.55 parts based on paint pigment were tested. At a given premix addition level, the Brookfield viscosity (Brookfield LVT, 60r.p.m.) of the paint increases as the premix addition concentration decreases (see Figure 2).

Effect of embodiment 9-poly-DADMAC/bentonite ratio

Diallyldimethylammonium chloride of high molecular weight (Mn=2-300,000, Reten 203, Hercules, Wilmington, DE) and low molecular weight (Mn=30,000, PRP-4440, Pearl River Polymers, Riceboro, Georgia) was used Polymer (poly-DADMAC) A bentonite/poly-DADMAC premix was prepared. High surface area bentonite clay (Bentolite H, Southern Clay Products) was used as anionic particles in the premix. The cationic polymer content of the premix was 5-50% of total solids (see Tables 5 and 6, 95%-50% bentonite). This premix was prepared using the method described in Example 1.

Each bentonite/poly-DADMAC premix was then tested for its effect on Brookfield viscosity and pigment shock of the kaolin/ground calcium carbonate based paint described in Example 3. The concentration of cationic polymer added can have a significant effect on its performance (Examples 7 and 8). Therefore, the addition level of each premix was chosen to obtain the same cationic polymer addition level (0.75%) throughout the range of bentonite/poly-DADMAC ratios. As shown in Tables 5 and 6, the % total solids of each premix and its added concentration varied with the ratio of poly-DADMAC to bentonite. In general, the increase in coating viscosity obtained at a given cationic polymer addition level increases as the percentage of cationic polymer in the premix increases. Therefore, adjust the amount of each premix added to get the same paint viscosity (approximately 2000 cps, Brookfield RV, 100 rpm, #4 or #5 spindle). Untreated paint (paint itself) was tested as a control. Measurements were also performed on the direct addition of high and low molecular weight poly-DADMAC cationic polymers to quantify the benefit of preforming the premix. The concentration of cationic polymer was fixed at 0.75% solids, which is the same concentration of cationic polymer added in the bentonite/poly-DADMAC premix.

Each treated paint (paint containing the additive premix) was then tested for pigment shock. As described in Example 7, the amount of grit remaining on a 200 mesh sieve of a 200 g paint sample was used as a measure of pigment shock. The results are shown in Table 5 and Table 6. Direct addition of either cationic poly-DADMAC polymer produced significant pigment shock. For pigment shocks of high and low molecular weight poly-DADMACs, premixes prepared with poly-DADMAC concentrations between 15%-30% (85%-70% bentonite) gave the best results. Premixes made within this range of poly-DADMAC additions gave greater paint viscosity increases and much less pigment shock than direct addition of the corresponding cationic polymers. Lower and higher concentrations of poly-DADMAC in the bentonite premix resulted in decreased performance. Premixes prepared between 7.5% and 15% poly-DADMAC loading and at 40% poly-DADMAC loading resulted in a large paint viscosity increase with moderate levels of pigment shock. Premixes prepared at poly-DADMAC premix addition levels of 5% and 50% resulted in similar pigment shocks as direct addition of the corresponding poly-DADMAC cationic polymer.

Based on these results, a bentonite/poly-DADMAC premix containing 7.5%-40% poly-DADMAC (92.5%-60% bentonite) bentonite/poly-DADMAC premixes are more preferred.

Example 10 - Pilot Coater Evaluation of Kaolin/Calcium Carbonate Coatings

The coating performance of the 85:15 bentonite:PRP-4440 premix was evaluated on a Western Michigan University cylinder test coater (CLC). The premix was prepared using the method described in Example 1 at 5% total solids. The clay/carbonate coating color and addition method was as described in Example 3. The addition level of the premix was fixed at 5% total solids. An uncoated wood pulp substrate was used as the substrate (38 g/m ² ). The coating speed was fixed at 925 m/min. Bentonite/PRP-4440 premixes were evaluated at 0.45 and 0.65 parts addition levels. An untreated paint was tested as a control. The gap spacing between the substrate and the coating blade was adjusted to bring a coating weight of 3-8 g/m ² for each side of the reference sample and bentonite: PRP-4440 treated coating. The coated paper was calendered 3 times at 65°C and 1000 lbs/linear inch prior to testing.

The test results for opacity and brightness of CLC coated papers are shown in Figures 3 and 4 . When compared across the coat weight range, the Bentonite:PRP-4440 treated coating had significantly higher opacity and brightness than the untreated control.

Example 11 - Effect of Bentonite/poly-DADMAC Addition Concentration

Bentonite/poly-DADMAC premixes with total solids concentrations ranging from 2.5% to 20% were prepared by diluting a 25% solids premix prepared using the method described in Example 4. Each premix was then tested for its effect on coating opacity and brightness. The study was conducted on a Western Michigan University Cylindrical Test Coater (CLC) using the 62% solids clay/carbonate coating formulation described in Example 3 and using the method described in Example 10. of. As shown in Figures 5 and 6 (best data regression fit), the increase in opacity and lightness obtained by adding 0.5 parts of the bentonite/poly-DADMAC premix decreased steadily with increasing concentration. Without wishing to be bound by theory, these results suggest that the increase in lightness and opacity obtained with the bentonite/poly-DADMAC premix correlates with the observed increase in Brookfield viscosity. Based on these results, an addition level of 10% total solids is preferred. Premix addition levels of less than 8% total solids are more preferred.

Example 12 - Effect of Bentonite/poly-DADMAC Stirring Time

The amount of pigment shock (hard pack in paint) formed by adding the bentonite/poly-DADMAC premix described in Example 4 was 10, 15, 20 after dilution from 25% total solids to 5% total solids , Measured within 25 and 30 minutes. The clay/carbonate paint formulation described in Example 3 was used for evaluation (64% solids). As shown in Figure 7, the amount of pigment shocks formed by adding the bentonite/poly-DADMAC premix to the paint decreased steadily within 25 minutes of starting stirring after dilution. Longer stirring times had no beneficial effect on the amount of pigment shocks formed on the paper coating. Based on these results, a stirring time of at least 25 minutes after dilution of the high solids premix is preferred. The study was performed at room temperature. Shorter times at higher temperatures may be sufficient.

Example 13 - Fixation of Coating Solids

Rapid fixation of paint solids (fixation at lower % solids as paint dry) correlates with increased paint brightness and opacity. The effect of the HPG stabilized bentonite:poly-DADMAC premix described in Example 4 on paint solids fixation was measured over a range of premix addition levels. The clay/carbonate coating described in Example 3 was used for this study. The premix was diluted to 5% solids and stirred for 25 minutes before adding it to the paint formulation. In each case, the coating solids were adjusted to 64% after the premix was added. As shown in Figure 8, the fixed point of the paint decreases steadily with increasing premix addition. These results suggest that bentonite:poly-DADMAC premixes can be used to control the fixation of coating solids.

Example 14 - Bentonite: poly-DADMAC premix and treated clay/carbonate Zeta Potential of Paint

A series of bentonite:PRP-4440 poly-DADMAC premixes were tested for zeta potential using a Malvern zeta Sizer and the method described by Lauzon (US Patent 5,169,441, incorporated herein by reference). The premix was prepared using the method described in Example 1. As shown in Table 7, the particles in all four premixes carried a positive zeta potential. It is well known that untreated bentonite has a negative zeta potential. The positive zeta potential measured in this study confirms the tight association of the cationic poly-DADMAC polymer to the bentonite particles.

Analysis of the pigment particles in the untreated clay/carbonate paint samples described in Example 3 showed that the particles carried a negative zeta potential of -25 to -28 millivolts. After treating the paint with 0.75 parts of the 85:15 bentonite:poly-DADMAC premix, the pigment particles in the clay/carbonate paint still carried a negative zeta potential (-24.8 millivolts). These results demonstrate that the addition of the bentonite:poly-DADMAC premix did not result in a "cationic" coating as described in the prior art.

Table 7 premix Zeta potential 95:5 bentonite: PRP-4440 +30.0 mV 85:15 bentonite: PRP-4440 +54.7 mV 75:25 bentonite: PRP-4440 +64.7 mV 65:35 bentonite: PRP-4440 +65.0 mV

Example 15 - Range of Cationic Polymers

Bentonite premixes are prepared using a wide range of cationic polymers. Cationic polymers tested included: Perform® ¹²⁷⁹ (Hercules, branched dimethylamine/ethylenediamine/epichlorohydrin polymer, _Mw = 500,000, positive charge of 5.8 meq/g), commercially available from Aldrich The resulting low molecular weight ( _Mw = 75,000, positive charge of 5.8 meq/g) dimethylamine/ethylenediamine/epichlorohydrin polymer, ^Kymene® 557 (Hercules, a polyamide amine described in U.S. Patent 2,926,154) Epichlorohydrin wet enhanced resin with a positive charge of 2.2 meq/g at pH 8), Kymene® 736 (Hercules, hexamethylenediamine/Tablet described in U.S. Pat. Chlorohydrin copolymer, having a positive charge of 4.0 meq/g at pH 8), polyethyleneimine (PEI, _Mw =50,000, commercially available from Aldrich, having about 8 meq/g at pH 8 gram positive charge), and acrylamide/diallyldimethylammonium chloride copolymer (commercially available from Aldrich with a positive charge of about 3 meq/gram). In each case, bentonite premixes were prepared with a wide range of cationic polymer additions, and high surface area bentonite (Bentolite H, Southern Clay Products) was used as the anionic particle of the premixes. The premix was prepared using the method described in Example 1. Prior to preparing the premix, the polyethyleneimine sample was neutralized to pH 8 with 10% HCl. The premix was not filtered after sonication.

Each bentonite/cationic polymer premix was then tested for its effect on Brookfield viscosity and pigment shock of the kaolin/ground calcium carbonate based paint described in Example 3. The direct addition of various cationic polymers was also tested in the experiment to quantify the benefit of pre-forming the premix. Test untreated paint as a reference. As described in Examples 7 and 8, the concentration of cationic polymer added can have a significant effect on its performance. For direct addition of cationic polymer, the solution concentration was fixed at 0.75% solids. Each premix addition level was chosen to obtain the same cationic polymer addition level (0.75%) across the range of bentonite/cationic polymer ratios. Thus, the % total solids of the various premixes varied with the ratio of bentonite to cationic polymer (see Tables 8-11). In general, the increase in coating viscosity obtained at a given cationic polymer addition level increases with increasing percentage of cationic polymer in the premix. Therefore, the addition levels of the various premixes are adjusted to obtain coating viscosities equal to or higher than those obtained by direct addition of the corresponding cationic polymers. Pigment shock was determined for each of the treated paints using the method described in Example 7 by measuring the amount of grit remaining on a 200 mesh sieve. The results obtained for each cationic polymer are described below.

Perform 1279 Dimethylamine/Ethylenediamine/Epichlorohydrin Copolymer Premix

Bentonite/cationic polymer premixes were prepared with Perform 1279 additions ranging from 10% to 70% (see Table 8, 90% to 30% bentonite).

Heavy pigment shock when added directly to Perform 1279 Cationic Polymer. When compared at the same paint viscosity, all bentonite/Perform 1279 premixes gave less pigment shock than direct addition of Perform 1279. Premixes containing 10%-20% Perform 1279 produced the best balance between increased viscosity and low levels of pigment shock. Based on these results, a premix containing 10%-70% Perform 1279 (90%-30% bentonite) is preferred. A premix containing 10%-20% Perform 1279 (80%-90% bentonite) is more preferred.

Dimethylamine/ethylenediamine/epichlorohydrin copolymer (DMA-epi) premix

A lower molecular weight branched dimethylamine/ethylenediamine/epichlorohydrin copolymer ( _Mw =75,000 Daltons, Aldrich, Milwaukee, WI, about 5.8 meq/gram) was also used to prepare the bentonite premix . As shown in Table 9, bentonite/cationic polymer premixes were prepared with 10%-90% addition of DMA-epi (90%-10% bentonite).

Heavy pigment shock when directly added to low molecular weight DMA-epi cationic polymer. When compared at the same paint viscosity, all bentonite/DMA-epi premixes gave less pigment shock than direct addition of cationic polymer. Premixes containing 20%-60% of low molecular weight DMA-epi cationic polymers produced the best balance between increased viscosity and low levels of pigment shock.

Based on these results, a premix containing 10%-90% DMA-epi (90%-10% bentonite) is preferred. Premixes containing 20%-60% DMA-epi (80%-40% bentonite) are more preferred.

It should also be noted that the low molecular weight DMA-epi cationic polymer produced a greater paint viscosity increase and less pigment shock than Perform 1279 (a high molecular weight DMA-epi cationic polymer). Based on these results and the results obtained for low and high molecular weight poly-DADMACs (PRP-4440 and Reten 203), cationic polymers having a molecular weight of from about 10,000 to about 1,000,000 Daltons are preferred. Cationic polymers having a molecular weight of from about 20,000 to about 500,000 Daltons are more preferred.

Kymene 557 Polyamide/Epichlorohydrin Premix

As shown in Table 10, bentonite/cationic polymer premixes were prepared with 10% to 90% addition of Kymene 557 (90% to 10% bentonite).

Adding Kymene 557 directly to the paint produced medium to heavy pigment shock. The degree of pigment shock increases with the addition of Kymene 557. When compared with the same paint viscosity, the best results were obtained with premixes made with 50%-70% Kymene 557 additions (50%-30% bentonite). Premixes made at the range of polymer loadings gave paint viscosity increases similar to those obtained with direct addition of Kymene 557, and with much less pigment shock. Premixes made at lower and higher Kymene 557 addition levels produced slightly less pigment shock than direct addition of Kymene 557 when compared to the same paint viscosity levels.

Based on these results, a premix containing 50%-70% Kymene 557 (50%-30% bentonite) is preferred. This Kymene 557 addition range is much higher than Lauzon's preferred range (Kymene 557 with 7.6% bentonite). Finally, it should be noted that Kymene 557 cationic polymer, which has a relatively low charge density, is not as effective at increasing paint viscosity as poly-DADMAC and DMA-epi polymers, which have higher charge densities.

Polyamine Epichlorohydrin (Kymene 736) Cationic Polymer/Bentonite Premix

As shown in Table 11, bentonite/cationic polymer premixes were prepared with additions of 10%-90% Kymene 736 (90%-10% bentonite). Adding Kymene 736 directly to the paint produces heavy pigment shock. Premixes prepared at 30%-70% Kymene 736 concentrations (70%-30% bentonite) gave the best results. Premixes made in this range of polymer additions gave paint viscosity increases similar to those obtained with direct addition of Kymene 736, and with much less pigment shock. Premixes made at lower Kymene 736 loadings gave low levels of pigment shock, but were much worse at increasing paint viscosity than premixes made with 30-70% Kymene 736. The Kymene 736/bentonite premix prepared with 80-90% Kymene 736 has a greater paint viscosity increase and less pigment shock than adding Kymene 736 directly.

Based on these results, a premix containing 10%-90% Kymene 736 (90%-10% bentonite) is preferred. Premixes containing 10%-70% Kymene 736 (90%-30% bentonite) are more preferred. A premix containing 30%-70% Kymene 736 (70%-30% bentonite) is most preferred.

Finally, it should be noted that Kymene 736, which has a relatively high charge density, gives a greater increase in paint viscosity than Kymene 557, which has a lower charge density.

Acrylamide/DADMAC Copolymer and PEI/Bentonite Preblend

Cationic polymer/bentonite premixes were prepared with acrylamide/DADMAC copolymer and 10%-90% PEI addition (90%-10% bentonite). None of these premixes gave the desired results. The acrylamide/DADMAC copolymer produced a flocculated premix causing severe pigment shock. The reasons for the poor performance of PEI premixes are currently not understood. Perhaps lower molecular weight, less branched, or chemically modified forms of the polymer can produce the desired results. As described in Example 17, better results were obtained when high surface area silica was used as the anionic particle instead of bentonite.

Example 16 - Range of Anionic Inorganic Particles

A series of premixes were prepared using silica or aluminum-modified silica as the anionic particles. These premixes were prepared using the method described in Example 2. The silicas used were: Ludox TM (22 nm particle size, 135 m ² /g), Ludox HS (12 nm particle size, 220 m ² /g) and Ludox FM (5 nm particle size, 420 m ² /g). All three silicas are commercially available from Grace-Davison (Columbia, Maryland). The aluminum-modified silicas used were: Ludox TMA (22 nm particle size, 140 m ² /g) and Ludox AM (12 nm particle size, 220 m ² /g). Both are commercially available from Grace-Davison (Columbia, Maryland). In each case, PRP-4440 poly-DADMAC was used as the cationic polymer component of the premix. The premix is prepared by adding PRP-4440 in an amount of 10%-90% of the total solids.

As shown in Tables 12-16, each premix was tested for its effect on the Brookfield viscosity and pigment shock of the kaolin/ground calcium carbonate based paint described in Example 3. An untreated paint with a viscosity of 450-500 cps (Brookfield RV, 100 rpm) was tested as a control. The direct addition of PRP-4440 poly-DADMAC was also tested to quantify the benefit of preforming the premix.

As described in Examples 7 and 8, the concentration of cationic polymer added can have a significant effect on its performance. For direct addition, the PRP-4440 solution concentration was fixed at 0.75% solids. The added concentration of each premix was chosen to give the same added concentration of PRP-4440 poly-DADMAC (0.75%) over the entire range of anionic particle/poly-DADMAC ratios. Thus, the % total solids of each premix varied with the ratio of anionic particles to cationic polymer (see Tables 12-16). As observed in the previous examples, the increase in coating viscosity obtained at a given cationic polymer addition level increased with increasing percentage of cationic polymer in the premix. Therefore, the addition amount of each premix was adjusted to obtain a coating viscosity equal to or higher than that obtained by adding PRP-4440 directly (1500-200 cps, see Table 12-16). The amount of pigment shock for each untreated paint was determined by measuring the amount of grit remaining on the 200 mesh screen using the method described in Example 7. Direct addition of 0.075 parts of PRP-4440 typically yielded 5-15 mg of kibble per 200 g of paint (see Tables 12-16). The results obtained with each of the silica and aluminum-modified silica anion particles are described below.

Ludox TM Silica/PRP-4440 Premix

Ludox™ premixes prepared at 10%-50% addition of PRP-4440 (see Table 12, 90%-50% Ludox™) produced the desired results. Premixes made at addition levels in this range have greater paint viscosity buildup and much less pigment shock than direct addition of PRP-4440. Best results were obtained with PRP-4440 additions of 15%-50% (85%-50% of Ludox™). These premixes effectively increase paint viscosity with little or no pigment thrashing. Higher additions of PRP-4440 in Ludox™ premixes resulted in heavy pigment shock.

Based on these results, a Ludox™ premix containing 10%-50% PRP-4440 (90%-50% Ludox™) is preferred. A Ludox™ premix containing 15%-50% PRP-4440 (85%-50% Ludox™) is more preferred.

Ludox HS Silica/PRP-4440 Premix

Ludox HS premixes prepared at 15%-90% addition of PRP-4440 (see Table 13, 85%-10% Ludox HS) produced the desired results. Premixes made with this range of additions have a greater increase in paint viscosity and much less pigment shock than direct addition of PRP-4440. The lower PRP-4440 addition level (10%) resulted in a poorer premix that formed grits in the coating.

Based on these results, a Ludox HS premix containing 15%-90% PRP-4440 (85%-10% Ludox HS) is preferred.

Ludox FM Silica/PRP-4440 Premix

Ludox FM premixes prepared at 20%-90% PRP-4440 additions (see Table 14, 80%-10% Ludox HS) gave the desired results. Premixes made with this range of additions have a greater increase in paint viscosity and much less pigment shock than direct addition of PRP-4440. Lower PRP-4440 addition levels (10%-15%) resulted in poorer premixes that formed grits in the coating.

Based on these results, a Ludox FM premix containing 20%-90% PRP-4440 (80%-10% Ludox FM) is preferred.

It should be pointed out that Ludox HS and Ludox FM gave better results than Ludox TM, especially at high PRP-4440 addition. It is believed that the differences in performance are caused by differences in anion particle size and surface area. Based on these results, silica with a particle size of less than 50 nm is preferred. Silica with a particle size of less than 20 nm is more preferred.

Ludox TMA Aluminum Modified Silica/PRP-4440 Premix

Ludox TMA premixes prepared with 10%-90% addition of PRP-4440 (see Table 15, 90%-10% Ludox TMA) gave the desired results. The premix prepared with the addition amount in this range has greater paint viscosity increase and less pigment shock than direct addition of PRP-4440. The best results were obtained at 15%-60% addition of PRP-4440 (85%-40% Ludox TMA). These premixes increase paint concentration as effectively as adding PRP-4440 directly with little or no pigment shock. Higher additions of PRP-4440 in the Ludox TMA premix resulted in slightly higher pigment shock. Lower PRP-4440 additions (10%) resulted in poorer premixes with slightly higher pigment shock formation.

Based on these results, a Ludox TMA premix containing 10%-90% PRP-4440 (90%-10% Ludox TMA) is preferred. A Ludox TMA premix containing 15%-60% PRP-4440 (85%-40% Ludox TMA) is more preferred.

Ludox AM Aluminum Modified Silica/PRP-4440 Premix

Ludox AM premixes prepared with 10%-90% addition of PRP-4440 (see Table 16, 90%-10% Ludox AM) gave the desired results. Premixes made with this range of addition have greater paint viscosity buildup and less pigment shock than direct addition of PRP-4440. The best results were obtained at 15%-60% addition of PRP-4440 (80%-40% Ludox AM). These premixes increase paint concentration as effectively as adding PRP-4440 directly with little or no pigment shock. Higher PRP-4440 additions in the Ludox AM premix resulted in moderate pigment shock. The lower addition level of PRP-4440 (10%) resulted in a poorer premix that formed a moderate amount of grit in the coating.

Based on these results, a Ludox AM premix containing 10%-90% PRP-4440 (90%-10% Ludox AM) is preferred. A Ludox AM premix containing 15%-60% PRP-4440 (85%-40% Ludox AM) is more preferred.

Example 17 - Polyethyleneimine/Silica Premix

PEI/Ludox HS silica premixes were prepared using the method described in Example 2 with PEI additions of 10%-50%. The various premixes were then tested for their effect on the Brookfield viscosity and pigment shock of the kaolin/ground calcium carbonate based paint described in Example 3.

Addition of PEI directly to the paper coating resulted in heavy pigment shock (see Table 17). PEI/Ludox HS premixes prepared with PEI additions of 10%-20% (90%-80% of Ludox HS) gave the desired properties. Premixes made at addition levels in this range had a greater paint viscosity increase and much less pigment shock than direct addition of PEI. Higher PEI additions result in heavy pigment shock. However, the pigment shock was still less than that caused by direct addition of PEI when compared to the same paint viscosity.

Based on these results, a Ludox HS premix containing 10%-50% PEI (90%-50% Ludox HS) is preferred. A Ludox HS premix containing 10%-20% PEI (90%-80% Ludox HS) is more preferred.

Example 18 - Acrylamide/DADMAC Copolymer/Silica Premix

Acrylamide/DADMAC copolymer/Ludox HS silica premixes were prepared using the method described in Example 2 at acrylamide/DADMAC addition levels of 10%-90%. Each premix was then tested for its effect on the Brookfield viscosity and pigment shock of the kaolin/ground calcium carbonate based paint described in Example 3.

Addition of acrylamide/DADMAC copolymer directly to the paper coating resulted in very heavy pigment shocks (see Table 18). Only the acrylamide/DADMAC copolymer/Ludox HS preblend prepared at an addition level of 70% gave the desired properties. Lower acrylamide/DADMAC additions produced poorly flocculated premixes. Higher additions of acrylamide/DADMAC copolymer produced heavy pigment shock. Based on these results, a Ludox HS premix containing approximately 70% acrylamide/DADMAC copolymer (30% Ludox HS) is preferred. Perhaps other acrylamide/DADMAC copolymers prepared at different molar ratios of acrylamide and poly-DADMAC or at different molecular weights may give better properties.

Example 19 - CLC Evaluation of Bentonite and Silica Premixes

Based on the results of Examples 15 and 16, a series of premixes were selected for evaluation on a cylindrical test coater. PRP-4440, Reten 203, 75,000 _Mw of DMA-epi cationic polymer, Kymene 557 and Kymene 736 were tested as the cationic polymer component of the premix. Bentonite, silica, and aluminum-modified silica were tested as anionic particulate components of the premix. Selected premix formulations are shown in Table 19. A 85:15 bentonite:poly-DADMAC premix was prepared at 25% solids using the method described in Example 5. The remaining premixes were prepared using the methods described in Examples 1 and 2. Evaluations were performed using the clay/carbonate coating formulation described in Example 3 and the cylindrical laboratory coater described in Example 10. In each case, the premix addition level was selected to give a cationic polymer addition level of 0.075 parts based on the paint pigment, and a cationic polymer addition concentration of 0.75%. Each premix was agitated at the chosen addition level for at least 25 minutes prior to addition to the paint. The 85:15 bentonite:poly-DADMAC premix was also tested using direct addition to the paint slurry without dilution. Untreated paint was evaluated as a control. Opacity and brightness of coated papers were measured using standard TAPPI (Technical Association of the Pulp and Paper Industry) methods.

Premixes prepared from low molecular weight, high charge density poly-DADMAC PRP-4440 gave the best results (see Table 19). The 85:15 bentonite:PRP-4440 premix yielded a 0.4-0.8 point increase in clarity and brightness on each coating side relative to the untreated control. Excellent the result of. A 70:30 bentonite:PRP-4440 premix gave similar increases in opacity and brightness. Preblends of silica made from PRP-4440 poly-DADMAC and aluminum-modified silica also significantly improved the optical properties of coated paper, especially opacity.

Premixes prepared with Reten 203, 75,000 _Mw of DMA-epi cationic polymer, Kymene 557 and Kymene 736 gave less paint opacity and increased brightness. In general, preblends prepared from high charge density cationic polymers have greater increases in opacity and brightness than preblends prepared from low charge density cationic polymers. For example, premixes made from Reten 203 or 75,000 _Mw of DMA-epi cationic polymer achieved 0.2-0.5 points in paint opacity and brightness (per coat side) increase. Bentonite premixes prepared from the relatively low charge density Kymene 557 and Kymene 736 cationic polymers showed only small increases in paint opacity and brightness (0-0.3 points per coat side). It is possible that Kymene 557 and Kymene 736 based preblends could achieve greater gains in opacity and brightness at addition levels above the 0.075 part cationic polymer used in this study.

Based on these results, cationic polymers having a cationic charge density of at least 2 meq/g are preferred. Cationic polymers having a cationic charge density of at least 4 meq/g are more preferred. Poly-DADMAC cationic polymers are most preferred. The premix can be prepared using bentonite, silica or aluminum-modified silica as anionic particles.

Table 4 % solids of (bentonite/cationic polymer) Hydroxypropyl Guar Gum initial viscosity precipitation stability 1 day 1 week 2 weeks 4 weeks 8 weeks twenty one% 0.4% 732cps pass thin and clear layer, fail - - - twenty one% 0.6% 1760cps pass pass thin and clear layer, fail - - twenty one% 0.7% 2170cps pass pass thin and clear layer, fail - - twenty one% 0.8% 2770cps pass pass pass pass thin and clear layer, fail twenty four% 0.4% 1020 cps pass thin and clear layer, fail - - - twenty four% 0.6% 2060cps pass pass pass thin and clear layer, fail - twenty four% 0.7% 2590cps pass pass pass pass thin and clear layer, fail twenty four% 0.8% 3390cps pass pass pass pass pass

Table 4 (continued) % solids of (bentonite/cationic polymer) Hydroxypropyl Guar Gum initial viscosity precipitation stability 1 day 1 week 2 weeks 4 weeks 8 weeks 27% 0.4% 1200cps pass thin and clear layer, fail - - - 27% 0.5% 1750 cps pass pass pass thin and clear layer, fail - 27% 0.6% 2510 cps pass pass pass pass thin and clear layer, fail 27% 0.7% 3080cps pass pass pass pass pass 30% 0.3% 988cps pass thin and clear layer, fail - - - 30% 0.4% 1610 cps pass pass thin and clear layer, fail - - 30% 0.5% 2220cps pass pass pass pass thin and clear layer, fail 30% 0.6% 3140cps pass pass pass pass pass

Table 5 - Bentonite/Reten 203 - Coating Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 470cps 0.3mg Reten 203 add directly - 0.75% 0.060% 965 cps 3.5mg Reten 203 add directly - 0.75% 0.075% 1690cps 3.2mg Reten 203 add directly - 0.75% 0.085% 2300cps 5.1mg Reten 203 95/5 15% 0.75% 0.10% 1475cps 5.9mg Reten 203 92.5/7.5 10% 0.75% 0.10% 2000cps 4.1mg Reten 203 90/10 7.5% 0.75% 0.10% 2180cps 4.5mg Reten 203 85/15 5.0% 0.75% 0.10% 2450 cps 1.8mg Reten 203 80/20 3.75% 0.75% 0.10% 2820 cps 0.7mg Reten 203 75/25 3.0% 0.75% 0.085% 3000 cps 1.3mg Reten 203 70/30 2.5% 0.75% 0.085% 3120cps 1.7mg Reten 203 60/40 1.88% 0.75% 0.085% 2450 cps 1.8mg Reten 203 50/50 1.5% 0.75% 0.085% 2520 cps 6.5mg

Table 6 - Bentonite/PRP-4440 - Coating Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 480cps 0.1mg PRP-4440 add directly - 0.75% 0.075% 1980cps 11.1mg PRP-4440 add directly - 0.75% 0.075% 2180cps 7.9mg PRP-4440 95/5 15% 0.75% 0.10% 1250 cps 6.7mg PRP-4440 92.5/7.5 10% 0.75% 0.10% 1730 cps 2.3mg PRP-4440 90/10 7.5% 0.75% 0.10% 1995cps 1.6mg PRP-4440 85/15 5.0% 0.75% 0.10% 2530cps 0.7mg PRP-4440 80/20 3.75% 0.75% 0.10% 2220 cps 1.9mg PRP-4440 75/25 3.0% 0.75% 0.085% 2190cps 0.1mg PRP-4440 70/30 2.5% 0.75% 0.085% 2160cps 1.0mg PRP-4440 60/40 1.88% 0.75% 0.085% 2420cps 4.9mg PRP-4440 50/50 1.5% 0.75% 0.075% 1850cps 7.4mg

Table 8 - Bentonite/Perform 1279 DMA - Epi, Mw _- 500,000 - Paint Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 470 cps 0.0mg Perform 1279 add directly - 0.75% 0.075% 1060cps 23.3mg Perform 1279 90/10 7.5% 0.75% 0.10% 925 cps 3.7mg Perform 1279 80/20 3.75% 0.75% 0.10% 1080cps 4.2mg Perform 1279 70/30 2.5% 0.75% 0.10% 1340cps 8.4mg Perform 1279 60/40 1.88% 0.75% 0.10% 1710cps 10.7mg Perform 1279 50/50 1.5% 0.75% 0.085% 1250 cps 14.4mg Perform 1279 40/60 1.25% 0.75% 0.085% 1360cps 15.2mg Perform 1279 30/70 1.07% 0.75% 0.085% 1810 cps 16.5mg

Table 9 - Bentonite/DMA-Epi, Mw _- 750,000 - Coating Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 450 cps 0.0mg DMA-Epi M _w -75,000 add directly - 0.75% 0.075% 1140cps 29.7mg DMA-Epi M _w -75,000 90/10 7.5% 0.75% 0.10% 900cps 4.0mg DMA-Epi M _w -75,000 80/20 3.75% 0.75% 0.10% 1150cps 0.6mg DMA-Epi M _w -75,000 70/30 2.5% 0.75% 0.10% 1560 cps 0.6mg DMA-Epi M _w -75,000 60/40 1.88% 0.75% 0.10% 1920 cps 0.9mg DMA-Epi M _w -75,000 50/50 1.5% 0.75% 0.085% 1900 cps 1.5mg DMA-Epi M _w -75,000 40/60 1.25% 0.75% 0.075% 1300 cps 1.7mg

Table 9 - Bentonite/DMA-Epi, Mw _- 750,000 - Coating Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) DMA-Epi M _w -75,000 30/70 1.07% 0.75% 0.075% 1380 cps 5.7mg DMA-Epi M _w -75,000 20/80 0.94 0.75% 0.075% 1490cps 5.2mg DMA-Epi M _w -75,000 10/90 0.84% 0.75% 0.075% 1700 cps 4.4mg

Table 10 - Bentonite/Kymene 557 - Coating Viscosity and Pigment Requirements polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 470cps 0.3mg Kymene 557 add directly - 0.75% 0.065% 685cps 2.9mg Kymene 557 add directly - 0.75% 0.075% 800cps 5.2mg Kymene 557 add directly - 0.75% 0.10% 960cps 15.4mg Kymene 557 90/10 7.5% 0.75% 0.10% 576cps 2.3mg Kymene 557 80/20 3.75% 0.75% 0.10% 752cps 2.3mg Kymene 557 70/30 2.5% 0.75% 0.10% 670cps 2.0mg Kymene 557 60/40 1.88% 0.75% 0.10% 650cps 2.4mg Kymene 557 50/50 1.5% 0.75% 0.10% 710cps 0.2mg Kymene 557 40/60 1.25% 0.75% 0.10% 720cps 0.1mg Kymene 557 30/70 1.07% 0.75% 0.10% 772 cps 0.8mg Kymene 557 20/80 0.94% 0.75% 0.10% 920 cps 5.5mg Kymene 557 10/90 0.84% 0.75% 0.10% 910 cps 3.2mg

Table 11 - Kymene 736 - Coating Viscosity and Pigment Shock polymer Bentonite/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 448 cps 0.7mg Kymene736 add directly - 0.75% 0.075% 1580 cps 9.6mg Kymene736 90/10 7.5% 0.75% 0.10% 688 cps 1.9mg Kymene736 80/20 3.75% 0.75% 0.10% 1060cps 0.8mg Kymene736 70/30 2.5% 0.75% 0.10% 1920 cps 0.0mg Kymene736 60/40 1.88% 0.75% 0.085% 1710 cps 1.8mg Kymene736 50/50 1.5% 0.75% 0.085% 2000cps 0.8mg Kymene736 40/60 1.25% 0.75% 0.085% 2590cps 2.0mg Kymene736 30/70 1.07% 0.75% 0.075% 1740 cps 0.6mg Kymene736 20/80 0.94% 0.75% 0.075% 2080cps 2.8mg Kymene736 10/90 0.84% 0.75% 0.075% 2210 cps 3.2mg

Table 12 - Ludox TM-50/PRP-4440 - Coating Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 470cps 0.2mg PRP-4440 add directly - - - 478cps 0.1mg PRP-4440 add directly - 0.75% 0.075% 2050cps 5.0mg PRP-4440 add directly - 0.75% 0.075% 1760cps 8.0mg PRP-4440 90/10 7.5% 0.75% 0.085% 1330 cps 0.8mg PRP-4440 90/10 7.5% 0.75% 0.090% 1610 cps 1.1mg PRP-4440 85/15 5.0% 0.75% 0.090% 2980cps 0.4mg PRP-4440 80/20 3.75% 0.75% 0.085% 2580cps 1.1mg PRP-4440 70/30 2.5% 0.75% 0.075% 2270cps 1.2mg PRP-4440 60/40 1.88% 0.75% 0.075% 1890 cps 0.3mg PRP-4440 50/50 1.5% 0.75% 0.075% 2540cps 0.7mg PRP-4440 40/60 1.25% 0.75% 0.075% 2170cps 11.4mg PRP-4440 40/60 1.25% 0.75% 0.075% 2225cps 18.5mg PRP-4440 30/70 1.07% 0.75% 0.065% 1640cps 10.8mg PRP-4440 20/80 0.94% 0.75% 0.065% 1735cps 10.3mg PRP-4440 10/90 0.84% 0.75% 0.065% 1820cps 11.1mg

Table 13 - Ludox HS/PRP-4440 - Coating Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 492cps 0.1mg PRP-4440 add directly - 0.75% 0.075% 1490cps 3.9mg PRP-4440 90/10 7.5% 0.75% 0.10% 820cps 2.6mg PRP-4440 85/15 5.0% 0.75% 0.10% 2330cps 0.3mg PRP-4440 80/20 3.75% 0.75% 0.10% 1970cps 0.1mg PRP-4440 70/30 2.5% 0.75% 0.085% 1620cps 0.7mg PRP-4440 60/40 1.88% 0.75% 0.085% 1800 cps 1.0mg PRP-4440 50/50 1.5% 0.75% 0.085% 2410cps 0.8mg PRP-4440 40/60 1.25% 0.75% 0.075% 1850cps 0.8mg PRP-4440 30/70 1.07% 0.75% 0.075% 1620cps 0.6mg PRP-4440 20/80 0.94% 0.75% 0.075% 1750cps 0.6mg PRP-4440 10/90 0.84% 0.75% 0.075% 1970cps 0.7mg

Table 14 - Ludox FM/PRP-4440 - Coating Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 455cps 0.3mg PRP-4440 add directly - 0.75% 0.075% 2015 cps 14.4mg PRP-4440 90/10 7.5% 0.75% 0.10% 905 cps 59.1mg PRP-4440 85/15 5.0% 0.75% 0.10% 664cps 4.7mg PRP-4440 80/20 3.75% 0.75% 0.10% 1280cps 1.1mg PRP-4440 70/30 2.5% 0.75% 0.085% 1890cps 1.1mg PRP-4440 60/40 1.88% 0.75% 0.085% 2390cps 1.6mg PRP-4440 50/50 1.5% 0.75% 0.075% 2010cps 1.9mg PRP-4440 40/60 1.25% 0.75% 0.075% 2450cps 2.4mg PRP-4440 30/70 1.07% 0.75% 0.065% 2410 cps 1.7mg PRP-4440 20/80 0.94% 0.75% 0.060% 1690cps 1.3mg PRP-4440 10/90 0.84% 0.75% 0.060% 1910cps 1.2mg

Table 15 - Ludox TMA/PRP-4440 - Coating Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 470 cps 0.3mg PRP-4440 add directly - 0.75% 0.065% 1920 cps 4.9mg PRP-4440 add directly - 0.75% 0.075% 2390cps 8.6mg PRP-4440 90/10 7.5% 0.75% 0.075% 1870cps 2.0mg PRP-4440 85/15 5.0% 0.75% 0.070% 1520cps 0.6mg PRP-4440 80/20 3.75% 0.75% 0.065% 2250cps 0.8mg PRP-4440 70/30 2.5% 0.75% 0.060% 1920 cps 0.7mg PRP-4440 60/40 1.88% 0.75% 0.060% 1760cps 0.7mg PRP-4440 50/50 1.5% 0.75% 0.060% 1680 cps 1.0mg PRP-4440 40/60 1.25% 0.75% 0.060% 1790cps 0.8mg PRP-4440 30/70 1.07% 0.75% 0.065% 2360cps 1.5mg PRP-4440 20/80 0.94% 0.75% 0.065% 2230cps 1.6mg PRP-4440 10/90 0.84% 0.75% 0.065% 2320cps 1.5mg

Table 16 - Ludox AM/PRP-4440 - Coating Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 452cps 0.0mg PRP-4440 add directly - 0.75% 0.075% 1800 cps 32.7mg PRP-4440 90/10 7.5% 0.75% 0.085% 1685 cps 6.5mg PRP-4440 85/15 5.0% 0.75% 0.085% 1410 cps 0.3mg PRP-4440 80/20 3.75% 0.75% 0.085% 2280cps 0.1mg PRP-4440 70/30 2.5% 0.75% 0.075% 2210 cps 0.9mg PRP-4440 60/40 1.88% 0.75% 0.070% 2040cps 0.4mg PRP-4440 50/50 1.5% 0.75% 0.065% 1675cps 0.4mg PRP-4440 40/60 1.25% 0.75% 0.065% 1890cps 0.4mg PRP-4440 30/70 1.07% 0.75% 0.065% 2020cps 2.5mg PRP-4440 20/80 0.94% 0.75% 0.060% 1710cps 2.8mg PRP-4440 10/90 0.84% 0.75% 0.060% 2240cps 2.1mg

Table 17 - Polyethyleneimine (PEI)/HS-40 Silica - Paint Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 480cps 1.4mg PEI add directly - 0.75% 0.065% 1260 cps 5.7mg PEI add directly - 0.75% 0.075% 1780cps 115.6mg PEI 90/10 7.5% 0.75% 0.085% 1100cps 0.5mg PEI 90/10 5.0% 0.75% 0.10% 1260 cps 1.5mg PEI 80/20 3.75% 0.75% 0.085% 1620cps 7.3mg PEI 70/30 2.5% 0.75% 0.085% 2310 cps 20.7mg PEI 60/40 1.88% 0.75% 0.085% 2400cps 33.5mg PEI 50/50 1.5% 0.75% 0.085% 2980cps 31.5mg

Table 18 - Acrylamide/DADMAC Copolymer (ACM/DADMAC)/HS-40 Silica - Paint Viscosity and Pigment Shock polymer Anionic particle/polymer ratio % Solids of Premix % solids of polymer Polymer addition paint viscosity Pigment shock (mg/200g) control blank - - - 480cps 1.4mg PEI add directly - 0.75% 0.075% 944 cps 79.8mg PEI 90/10 7.5% 0.75% 0.085% 608cps 547mg PEI 70/30 2.5% 0.75% 0.10% - Severe pigment shock, unable to filter PEI 50/50 1.5% 0.75% 0.10% - Severe pigment shock, unable to filter PEI 40/60 1.25% 0.75% 0.10% - Severe pigment shock, unable to filter PEI 30/70 1.07% 0.75% 0.10% 1210cps 12.8mg PEI 20/80 0.94% 0.75% 0.10% 1240cps 51.2mg PEI 10/90 0.84% 0.75% 0.10% - Severe pigment shock, unable to filter

Table 19 - Increase in Brightness and Opacity of Coated Papers premix Average increase in brightness of coated paper per side Average increase in opacity of coated paper per side untreated control - - 85:15: Bentonite: PRP-4440 diluted, added last 0.42 points 0.84 points 85:15: Bentonite: PRP-4440 undiluted, added to starch 0.39 points 0.65 points 70:30: Bentonite: PRP-4440 0.62 points 0.54 points 85:15: Bentonite: Reten 203 0.49 points 0.23 points 70:30 bentonite: 75,000 M _w DMA-epi 0.39 points 0.42 points 50:50 bentonite: Kymene 736 0.10 points 0.31 points 40:60 bentonite: Kymene 557 0.27 points 0.0 point 70:30 Ludox FM Silica: PRP-4440 0.13 points 0.65 points 70:30 Ludox TM silica: PRP-4440 0.23 points 0.76 points 70:30 Ludox AM aluminum modified silica: PRP-4440 0.28 points 0.67 points

Claims (111)

1. A pigmented aqueous system comprising: (i) Additive premix containing cationic polymer and anionic particles. 2. The system of claim 1, wherein said system comprises the premix in an amount of from about 0.01 to about 2.0 dry parts per 100 parts of pigment in said aqueous system. 3. The system of claim 2, wherein said system contains the premix in an amount of from about 0.05 to about 1.0 dry parts per hundred parts of pigment in said aqueous system. 4. The system of claim 3, wherein said system comprises from about 0.1 to about 0.5 dry parts of premix per 100 parts of pigment in said aqueous system. 5. The system of claim 1, wherein said premix has a solids content of from about 5% to about 40%. 6. The system of claim 5, wherein said premix has a solids content of from about 15% to about 30%. 7. The system of claim 1, wherein said cationic polymer has a weight average molecular weight of from about 5,000 to about 3,000,000 Daltons. 8. The system of claim 7, wherein the cationic polymer has a weight average molecular weight of from about 10,000 to about 1,000,000 Daltons. 9. The system of claim 8, wherein the cationic polymer has a weight average molecular weight of from about 20,000 to about 500,000 Daltons. 10. The system of claim 1, wherein said cationic polymer has a charge density of from about 0.1 to about 8 meq/gram. 11. The system of claim 10, wherein said cationic polymer has a charge density of from about 1 to about 8 meq/gram. 12. The system of claim 11, wherein said cationic polymer has a charge density of from about 2 to about 6.5 meq/gram. 13. The system of claim 1, wherein said cationic polymer comprises: a quaternary ammonium salt of an N-alkyl substituted aminoalkyl (meth)acrylic acid ester (co)polymer; a polyamine reacted with an acrylate Quaternary ammonium salt of the product; (co)polymer of (methacryloyloxyethyl)trimethylammonium chloride; (co)polymer of acrylamide and quaternary ammonium compound; quaternized vinyl lactam- Acrylamide (co)polymers; quaternary ammonium salts of hydroxyl-containing unsaturated carboxylic acid polyesters; quaternary ammonium salts of polyimide-amines; quaternized polyamines; reaction of quaternization of amines and polyesters Products; quaternary ammonium salts of condensation (co)polymers of polyvinylamine and ethylene dichloride; quaternized condensation products of polyalkylene-polyamines with epoxy halides; alkylene-polyamines with polyfunctional Quaternized condensation products of halogenated alcohols; quaternized condensation products of alkylene-polyamines and halogenated alcohols; quaternized condensation (co)polymers of ammonia and halogenated alcohols; polyvinylbenzyltri Quaternary ammonium salts of alkylamines; quaternary ammonium salts of (co)polymers of vinyl-heterocyclic monomers with ring nitrogen; polydialkyldienes including polydiallyldimethylammonium chloride Propylammonium salts; (co)polymers of ethylenically unsaturated acids, their esters and amides with diallyldialkylammonium salts; polymethacrylamidopropyltrimethylammonium chloride; ammonia-di Quaternary ammonium salts of vinyl chloride condensation (co)polymers; quaternary ammonium salts of epoxy halide (co)polymers, and mixtures thereof. 14. The system of claim 13, wherein said cationic polymer comprises: (co)polymers of diallyldialkylammonium salts; (co)polymers of diallylamine; diallylalkyl (co)polymers of amines; polyethyleneimines; (co)polymers of dialkylamine/epichlorohydrin; (co)polymers of polyamine/epichlorohydrin; (co)polymers of polyamide/epichlorohydrin ) polymers; polyamidoamine (co)polymers; polyamidoamine/epichlorohydrin (co)polymers; dialkylaminoalkylacrylamide and methacrylamide (co)polymers and quaternary ammonium (co)polymers; and (co)polymers of dialkylaminoalkylacrylates, methacrylates and quaternized (co)polymers; and mixtures thereof. 15. The system of claim 14, wherein said cationic polymer comprises: a (co)polymer of diallyldimethylammonium salt; a (co)polymer of polyamine/epichlorohydrin; polyethyleneimine; (Co)polymers of dimethylamine/epichlorohydrin; polymers of polyamidoamine/epichlorohydrin; and mixtures thereof. 16. The system of claim 15, wherein said cationic polymer comprises: a (co)polymer of diallyldimethylammonium salt, a (co)polymer of dimethylamine/epichlorohydrin, and mixtures thereof. 17. The system of claim 1, wherein the concentration of the cationic polymer in the premix is less than about 2.5%. 18. The system of claim 17, wherein the concentration of the cationic polymer in the premix is less than about 1.5%. 19. The system of claim 18, wherein the concentration of the cationic polymer in the premix is less than about 1.0%. 20. The system of claim 1, wherein said anionic particles are high surface area anionically charged inorganic minerals, high surface area anionically charged synthetic inorganic particles, and mixtures thereof. 21. The system of claim 20, wherein said anionic particles comprise swelling clays, silica-based particles, and mixtures thereof. 22. The system of claim 21, wherein the silica-based particles comprise colloidal silica, colloidal aluminum-modified silica, aluminum silicate, and mixtures thereof. 23. The system of claim 21, wherein the swelling clay comprises bentonite, montmorillonite, montmorillonite, beidellite, nontronite, hectorite, saponite, sepiolite, or attapulgite. 24. The system of claim 23, wherein said anionic particle is bentonite. 25. The system of claim 21, wherein said swelling clay has a particle size of from about 1 nanometer to about 1 micrometer. 26. The system of claim 21, wherein said swelling clay has a surface area of at least 50 ^m2 /g. 27. The system of claim 26, wherein the swelling clay has a surface area of at least 100 ^m2 /g. 28. The system of claim 27, wherein the expansive clay has a surface area of at least 200 ^m2 /g. 29. The system of claim 21, wherein the silica-based particles have a particle size of less than about 50 nanometers. 30. The system of claim 29, wherein the silica-based particles have a particle size of less than about 20 nanometers. 31. The system of claim 30, wherein the silica-based particles have a particle size of about 1 to about 10 nanometers. 32. The system of claim 21, wherein the silica-based particles have a surface area of at least 50 ^m2 /g. 33. The system of claim 32, wherein the silica-based particles have a surface area of at least 100 ^m2 /g. 34. The system of claim 33, wherein the silica-based particles have a surface area of at least about 200 ^m2 /g. 35. The system of claim 1, wherein the additive premix comprises from about 95% to about 10% by weight anionic particles and from about 5% to about 80% by weight cationic polymer. 36. The system of claim 35, wherein the additive premix comprises from about 90% to about 20% by weight anionic particles and from about 10% to about 80% by weight cationic polymer. 37. The system of claim 36, wherein the additive premix comprises from about 90% to about 40% by weight anionic polymer and from about 10% to about 60% by weight cationic polymer. 38. The system of claim 37, wherein the additive premix comprises from about 85% to about 60% by weight anionic particles and from about 15% to about 40% by weight cationic polymer. 39. The system of claim 1, wherein said anionic particle is bentonite and said cationic polymer is poly-DADMAC. 40. The system of claim 39, wherein the ratio of bentonite to poly-DADMAC is from about 92.5:7.5 to about 60:40, respectively. 41. The system of claim 40, wherein the ratio of bentonite to poly-DADMAC is about 70:30 to about 85:15, respectively. 42. A paper coated with a coating comprising the pigmented aqueous system of claim 1. 43. A method of forming an aqueous system comprising: (1) mixing anionic particles and cationic polymers; wherein an additive premix is formed, (2) optionally filtering the additive premix; (3) optionally adding a stabilizer to the additive premix; (4) optionally adding the additive premix to the coating slurry; (5) optionally adding an antimicrobial agent to the additive premix; and (6) Add the additive premix to the aqueous system. 44. The method of claim 43, further comprising: (7) coating the cellulosic substrate; and (8) Drying the cellulose substrate. 45. The method of claim 43, wherein said cationic polymer comprises: a (co)polymer of diallyldialkylammonium salt; a (co)polymer of diallylamine; diallylalkyl (co)polymers of amines; polyethyleneimines; (co)polymers of dialkylamine/epichlorohydrin; (co)polymers of polyamine/epichlorohydrin; (co)polymers of polyamide/epichlorohydrin ) polymers; polyamidoamine (co)polymers; polyamidoamine/epichlorohydrin (co)polymers; dialkylaminoalkylacrylamide and methacrylamide (co)polymers and quaternary ammonium (co)polymers; and (co)polymers of dialkylaminoalkylacrylates, methacrylates and quaternized (co)polymers; and mixtures thereof. 46. The method of claim 45, wherein said cationic polymer comprises: a (co)polymer of diallyldimethylammonium salt; a (co)polymer of polyamine/epichlorohydrin; polyethyleneimine; (Co)polymers of dimethylamine/epichlorohydrin; polymers of polyamidoamine/epichlorohydrin; and mixtures thereof. 47. The method of claim 46, wherein said cationic polymer comprises: a (co)polymer of diallyldimethylammonium salt, a (co)polymer of dimethylamine/epichlorohydrin, and mixtures thereof. 48. The method of claim 43, wherein the concentration of the cationic polymer in the premix is less than about 2.5%. 49. The method of claim 48, wherein the concentration of the cationic polymer in the premix is less than about 1.5%. 50. The method of claim 49, wherein the concentration of the cationic polymer in the premix is less than about 1.0%. 51. The method of claim 43, wherein the anionic particles are high surface area anionically charged inorganic minerals, high surface area anionically charged synthetic inorganic particles, and mixtures thereof. 52. The method of claim 51, wherein the anionic particles comprise swelling clays, silica-based particles, and mixtures thereof. 53. The method of claim 52, wherein the silica-based particles comprise colloidal silica, colloidal aluminum-modified silica, aluminum silicate, and mixtures thereof. 54. The method of claim 52, wherein the swelling clay comprises bentonite, montmorillonite, montmorillonite, beidellite, nontronite, hectorite, saponite, sepiolite, or attapulgite. 55. The method of claim 54, wherein the anionic particle is bentonite. 56. The method of claim 52, wherein the particle size of the swelling clay is from about 1 nanometer to about 1 micrometer. 57. The method of claim 52, wherein the swelling clay has a surface area of at least 50 ^m2 /g. 58. The method of claim 57, wherein the swelling clay has a surface area of at least 100 ^m2 /g. 59. The method of claim 58, wherein the swelling clay has a surface area of at least 200 ^m2 /g. 60. The method of claim 43, wherein the silica-based particles have a particle size of less than about 50 nanometers. 61. The method of claim 60, wherein the silica-based particles have a particle size of less than about 20 nanometers. 62. The method of claim 61, wherein the silica-based particles have a particle size of about 1 to about 10 nanometers. 63. The method of claim 43, wherein the silica-based particles have a surface area of at least 50 ^m2 /g. 64. The method of claim 63, wherein the silica-based particles have a surface area of at least 100 ^m2 /g. 65. The method of claim 64, wherein the silica-based particles have a surface area of at least about 200 ^m2 /g. 66. The method of claim 43, wherein said stabilizer is nonionic or cationic. 67. The method of claim 43, wherein said stabilizer comprises: hydroxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose modified with butyl glycidyl ether, hydroxypropyl cellulose, methyl hydroxyethyl cellulose cellulose, methyl hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, poly-N-vinylpyrrolidone, polyvinyl alcohol, polyethylene oxide, polypropylene oxide, polyacrylamide, starch ether, Starch esters, oxidized starch, guar gum, pectin, carrageenan, locust bean gum, xanthan gum, water-soluble protein, hydrophobic associative paint thickener, cationic starch, hydroxyethyl cellulose, Hydroxypropyl guar gum and cationic guar gum. 68. The method of claim 67, wherein the stabilizer comprises hydroxypropyl guar or hydroxyethylcellulose. 69. The method of claim 68, wherein the stabilizer is hydroxypropyl guar gum. 70. The method of claim 43, wherein said stabilizer is added in an amount of about 0.1% to about 5% based on the total weight of said premix. 71. The method of claim 70, wherein the stabilizer is added in an amount of about 0.2% to about 1.0% based on the total weight of the premix. 72. The method of claim 71, wherein the stabilizer is added in an amount of about 0.3% to about 0.7% based on the total weight of the premix. 73. The method of claim 43, wherein the viscosity of the aqueous system is at least 1000 cps. 74. The method of claim 73, wherein the viscosity of the aqueous system is at least 2000 cps. 75. The method of claim 74, wherein the viscosity of the aqueous system is at least 3000 cps. 76. The method of claim 43, wherein the viscosity of the aqueous system is from about 2000 to about 3500 cps. 77. A cellulosic substrate coated by the method of claim 44. 78. A method of preparing a stable premix comprising: (a) forming a premix comprising anionic particles and a cationic polymer; (b) adding a stabilizer to said premix, wherein a stable premix is formed; and (c) Optionally adding an antimicrobial agent to said premix. 79. The method of claim 78, wherein said cationic polymer comprises: a (co)polymer of diallyldialkylammonium salt; a (co)polymer of diallylamine; diallylalkyl (co)polymers of amines; polyethyleneimines; (co)polymers of dialkylamine/epichlorohydrin; (co)polymers of polyamine/epichlorohydrin; (co)polymers of polyamide/epichlorohydrin ) polymers; polyamidoamine (co)polymers; polyamidoamine/epichlorohydrin (co)polymers; dialkylaminoalkylacrylamide and methacrylamide (co)polymers and quaternary ammonium (co)polymers; and (co)polymers and quaternized (co)polymers of dialkylaminoalkylacrylates and methacrylates; and mixtures thereof. 80. The method of claim 79, wherein said cationic polymer comprises: a (co)polymer of diallyldimethylammonium salt; a (co)polymer of polyamine/epichlorohydrin; polyethyleneimine; (Co)polymers of dimethylamine/epichlorohydrin; polymers of polyamidoamine/epichlorohydrin; and mixtures thereof. 81. The method of claim 80, wherein the cationic polymer comprises a (co)polymer of diallyldimethylammonium salt, a (co)polymer of dimethylamine/epichlorohydrin, and mixtures thereof. 82. The method of claim 78, wherein the concentration of the cationic polymer in the premix is less than about 2.5%. 83. The method of claim 82, wherein the concentration of the cationic polymer in the premix is less than about 1.5%. 84. The method of claim 83, wherein the concentration of the cationic polymer in the premix is less than about 1.0%. 85. The method of claim 78, wherein the anionic particles are high surface area anionically charged inorganic minerals, high surface area anionically charged synthetic inorganic particles, and mixtures thereof. 86. The method of claim 85, wherein the anionic particles comprise swelling clays, silica-based particles, and mixtures thereof. 87. The method of claim 86, wherein the silica-based particles comprise colloidal silica, colloidal aluminum-modified silica, aluminum silicate, and mixtures thereof. 88. The method of claim 86, wherein the swelling clay comprises bentonite, montmorillonite, montmorillonite, beidellite, hectorite, nontronite, saponite, sepiolite, or attapulgite. 89. The method of claim 88, wherein the anionic particle is bentonite. 90. The method of claim 86, wherein the particle size of the swelling clay is from about 1 nanometer to about 1 micrometer. 91. The method of claim 86, wherein the swelling clay has a surface area of at least 50 ^m2 /g. 92. The method of claim 91, wherein the swelling clay has a surface area of at least 100 ^m2 /g. 93. The method of claim 92, wherein the swelling clay has a surface area of at least 200 ^m2 /g. 94. The method of claim 86, wherein the silica-based particles have a particle size of less than about 50 nanometers. 95. The method of claim 86, wherein the silica-based particles have a particle size of less than about 20 nanometers. 96. The method of claim 95, wherein the silica-based particles have a particle size of about 1 to about 10 nanometers. 97. The method of claim 86, wherein the silica-based particles have a surface area of at least 50 ^m2 /g. 98. The method of claim 97, wherein the silica-based particles have a surface area of at least 100 ^m2 /g. 99. The method of claim 98, wherein the silica-based particles have a surface area of at least about 200 ^m2 /g. 100. The method of claim 78, wherein said stabilizer is nonionic or cationic. 101. The method of claim 78, wherein said stabilizer comprises: hydroxymethyl hydroxyethyl cellulose, butyl glycidyl ether modified hydroxyethyl cellulose, hydroxypropyl cellulose, methyl hydroxyethyl cellulose cellulose, methyl hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, poly-N-vinylpyrrolidone, polyvinyl alcohol, polyethylene oxide, polypropylene oxide, polyacrylamide, starch ether, Starch esters, oxidized starch, guar gum, pectin, carrageenan, locust bean gum, xanthan gum, water-soluble proteins and hydrophobic associative paint thickeners, cationic starch, hydroxyethyl cellulose, Hydroxypropyl guar gum and cationic guar gum. 102. The method of claim 101, wherein the stabilizer comprises hydroxypropyl guar or hydroxyethylcellulose. 103. The method of claim 102, wherein the stabilizer is hydroxypropyl guar gum. 104. The method of claim 78, wherein the stabilizer is added in an amount of about 0.1% to about 5% based on the total weight of the premix. 105. The method of claim 104, wherein the stabilizer is added in an amount of about 0.2% to about 1.0% based on the total weight of the premix. 106. The method of claim 105, wherein the stabilizer is added in an amount of about 0.3% to about 0.7% based on the total weight of the premix. 107. The method of claim 78, wherein the stable premix viscosity is at least 1000 cps. 108. The method of claim 107, wherein the stable premix viscosity is at least 2000 cps. 109. The method of claim 108, wherein the stable premix viscosity is at least 3000 cps. 110. The method of claim 78, wherein said stable premix has a viscosity of about 2000 to about 3500 cps. 111. A stabilized anionic particle/cationic polymer premix prepared according to the process of claim 78.

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