Aqueous composition

Abstract

An aqueous composition comprises water, a binder, optionally a pigment, and particles. The particles themselves comprise at least one core polymer and at least one shell polymer. The at least one core polymer and the at least one shell polymer are polymerization reaction products of a mixture of a first monomer and a second monomer, respectively. The first and second monomer mixtures each comprise: a1) / a2) optionally one or more anionic ethylenically unsaturated monomers; b1) / b2) optionally one or more short-chain hydrophobic ethylenically unsaturated monomers, the side chain of which comprises a hydrophobic group having 7 or less carbon atoms; c1) / c2) optionally one or more associative monomers; d1) / d2) optionally one or more crosslinking monomers; e1) / e2) optionally one or more nonionic ethylenically unsaturated monomers; and f1) / f2) optionally one or more long-chain hydrophobic ethylenically unsaturated monomers, the side chain of which comprises a hydrophobic group having 8 or more carbon atoms.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 493,084, filed March 30, 2023, and U.S. Provisional Application No. 63 / 359,323, filed February 29, 2024, the disclosure of each of which is expressly incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to an aqueous composition comprising particles that are typically alkali-swellable and capable of providing customizable viscosity properties to the composition. More specifically, the particles comprise at least one core polymer and at least one shell polymer disposed around the at least one core polymer, wherein the at least one shell polymer is at least partially crosslinked. Background Technology

[0004] Aqueous compositions are used in a variety of industries, including but not limited to paints, coatings, adhesives, and asphalt. Depending on the application, adjusting the rheological properties of such compositions can be challenging because they often need to exhibit additional physical properties such as leveling, anti-sagging, stability, pH, solubility, compatibility, and surface tension.

[0005] To give just one example, in paints, it can be difficult to simultaneously achieve both medium-shear and high-shear viscosities, especially if only one rheology modifier is used. KU viscosity and ICI viscosity are both important measures of paint consistency because they affect paint performance and application characteristics. For instance, paints with high KU or ICI viscosity will be thicker and may be more difficult to apply evenly, while paints with low KU or ICI viscosity may be too thin and may not provide sufficient coverage. It is crucial for paint manufacturers to carefully control these viscosity values ​​to ensure their products perform as expected.

[0006] Nonionic synthetic associative thickeners (NSATs) are commonly used across various industries to control the viscosity and rheological properties of aqueous compositions. While they offer numerous advantages, such as improved performance and stability, their use also presents several potential challenges. For example, NSATs may be incompatible with certain formulations or ingredients, leading to problems such as phase separation, reduced efficacy, or changes in appearance. Furthermore, the performance of NSATs can vary depending on factors such as temperature, shear rate, and the presence of other additives. This variability makes predicting and controlling the rheological properties of the final product challenging.

[0007] NSATs can also be sensitive to changes in formulation parameters, such as the type or concentration of other additives. Small changes in formulation can sometimes result in dramatic changes in viscosity or rheological behavior. In certain formulations, NSATs can cause syneresis, i.e., the separation of liquid from a gel or paste. Some NSATs can have environmental impacts due to their chemical composition or manufacturing process.

[0008] Accordingly, there remains an opportunity to develop aqueous compositions containing novel rheology modifiers that can be used alone or with NSATs. SUMMARY

[0009] The present disclosure provides an aqueous composition comprising water, a binder, optionally a pigment, and a particle. The particle itself comprises at least one core polymer and at least one shell polymer disposed around the at least one core polymer. The at least one core polymer is a polymerization reaction product of a first monomer mixture. The first monomer mixture comprises: al) optionally one or more anionic ethylenically unsaturated monomers; bl) optionally one or more short chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 7 or fewer carbon atoms; cl) optionally one or more associative monomers; dl) optionally one or more crosslinking monomers; el) optionally one or more non-ionic ethylenically unsaturated monomers; and fl) optionally one or more long chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 8 or more carbon atoms. In this first monomer mixture, if al) is not present, then el) is present in the first monomer mixture. Further, if fl) is not present in the first monomer mixture, then al) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the first monomer mixture. Still further, if fl) is present in the first monomer mixture, then al) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the first monomer mixture. However, at least one of bl) and fl) is present in the first monomer mixture. Now directed to the at least one shell polymer, the at least one shell polymer is at least partially crosslinked and is a polymerization reaction product of a second monomer mixture. The second monomer mixture comprises: a2) optionally one or more anionic ethylenically unsaturated monomers; b2) optionally one or more short chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 7 or fewer carbon atoms; c2) optionally one or more associative monomers; d2) one or more crosslinking monomers; e2) optionally one or more non-ionic ethylenically unsaturated monomers; and f2) optionally one or more long chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 8 or more carbon atoms. In this second monomer mixture, if a2) is not present, then e2) is present in the second monomer mixture. Further, if f2) is not present in the second monomer mixture, then a2) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the second monomer mixture. Still further, if f2) is present in the second monomer mixture, then a2) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the second monomer mixture. Additionally, at least one of b2) and f2) is present in the second monomer mixture, while at least one of al) or a2) in the first monomer mixture and the second monomer mixture, respectively, comprises greater than 0 mol%. BRIEF DESCRIPTION OF DRAWINGS

[0010] The present disclosure will be described with respect to the following drawings in which the same numbers on different drawings represent the same elements, and

[0011] Figure 1 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer;

[0012] Figure 2 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer;

[0013] Figure 3 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer;

[0014] Figure 4 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer;

[0015] Figure 5 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer;

[0016] Figure 6 is a cross-sectional view of one embodiment of a particle of the present disclosure, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer, and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer. DETAILED DESCRIPTION

[0017] The following detailed description is merely exemplary in nature and is not intended to limit the aqueous compositions of the application. Furthermore, there is no intention that the application be limited by any of the examples, or examples set forth in the following detailed description. Further, there is no intention that the application be limited by any theory of operation presented in the preceding background or the following detailed description.

[0018] Embodiments of the present disclosure generally relate to polymers, compositions including the polymers, and methods of making the polymers and compositions. For the sake of brevity, the conventional techniques related to the methods of making the polymers and compositions will not be described in detail herein. Additionally, the procedures and process steps described herein can be incorporated into more comprehensive procedures or processes that have other steps or functions not described in detail herein. In particular, the procedures for making the polymers and related compositions are well known, and thus, for the sake of brevity, only a brief description of these conventional procedures will be provided herein, and the well-known process details will not be provided.

[0019] In the present disclosure, the term "about" can describe a numerical value ± 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% in various embodiments. Further, it should be understood that, in various non-limiting embodiments, all numerical values provided herein are approximations, and the end value or particular value should be understood to be "about" or "approximately" the value stated. Further, it should be understood that all isomers and chiral options of each compound described herein are expressly contemplated for use in various non-limiting embodiments herein.

[0020] Throughout the disclosure, the term percent "actives" is art-recognized and refers to the percentage content of active or effective compounds or molecules relative to the total weight of, for example, a solvent and a dilute solution of the compound. Certain compounds (e.g., solvents) are not described in terms of percent actives because it is well known that their active content is approximately 100%. It will be understood by those skilled in the art that any one or more of the values described herein can also be described in terms of percent actives.

[0021] In various embodiments, the term "free of" describes embodiments in which the content of the compound or element in question is less than about 5, 4, 3, 2, 1, 0.5, or 0.1 weight percent (or percent actives by weight) based on the appropriate weight as understood by those skilled in the art. In other embodiments, the term "free of" describes embodiments in which the weight percent of the compound or element in question is zero.

[0022] The term "consisting essentially of can describe various non-limiting embodiments that are free of one or more of the optional compounds described herein and / or free of one or more of the polymers, surfactants, additives, solvents, etc.

[0023] It should be appreciated that the subscripts of the polymers are generally expressed as averages, as the synthesis of the polymers will generally result in a distribution of different individual molecules.

[0024] The polymers and compositions disclosed herein can suitably comprise, consist of, or consist essentially of the components, elements, or process flows described herein. The illustrative embodiments disclosed herein can suitably be implemented in the absence of any element not specifically disclosed herein.

[0025] Aqueous composition

[0026] The present disclosure provides an aqueous composition, which can be alternatively described herein as a "composition." The aqueous composition is not particularly limited in terms of use or application. For example, the aqueous composition can be alternatively described as an aqueous coating composition, an aqueous paint composition, an aqueous adhesive composition, an aqueous asphalt composition, and the like. Alternatively, the aqueous composition can be used as one component in a larger and otherwise aqueous or non-aqueous composition, such as a coating composition, a paint composition, an adhesive composition, an asphalt composition, and the like. The aqueous composition includes water and particles as described below.

[0027] In various embodiments, the aqueous composition is further defined as an aqueous coating composition. The aqueous coating composition generally includes water (and / or a solvent), a binder, optional pigments, and the particles. In various embodiments, the aqueous coating composition is, consists essentially of, or consists of water (and / or a solvent), a binder, optional pigments, and the particles. In any of these embodiments, a non-ionic synthetic associative thickener can be included or omitted, as described in detail below.

[0028] Water and / or solvent

[0029] The term "aqueous" as used herein generally describes that the composition includes a sufficient amount of water (and / or a polar solvent) to at least swell or dissolve the particles formulated into the composition. In various embodiments, the solvent can use water itself or can be a combination of water and a water-miscible solvent. The solvent can be described as any polar solvent known in the art. For example, the polar solvent can be or can include an alcohol such as ethanol or methanol, butanol, isobutyl alcohol, acetone, methyl ethyl ketone, isopropyl alcohol, n-propyl alcohol, acetonitrile, DMSO (dimethyl sulfoxide), DMF (dimethylformamide), ether alcohol, butyl cellosolve, dipropylene glycol monomethyl ether, or a combination thereof. In one embodiment, the solvent is water, free of any additional polar solvent.

[0030] In other embodiments, the solvent can be or can include an organic solvent, which can be polar or non-polar. However, most typically, if used, the organic solvent will be present in small amounts as a co-solvent with the water or polar solvent described above. Generally, no organic solvent is used. In various embodiments, glycols can be used as open time extenders in compositions, such as aqueous coating compositions. In addition, coalescing agents such as Texanol, e.g., Texanol 25265-77-4 77-68-9, 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, can also be used.

[0031] However, if an organic solvent is used, the solvent can be a polar organic liquid, such as an ether, especially a lower alkyl ether, an ester, a ketone, a glycol, an alcohol, an amide, or combinations thereof. In one embodiment, the polar organic liquid includes dialkyl ketones, alkyl esters of alkyl carboxylic acids and alkanols, especially such liquids containing up to and in total 6 or 8 carbon atoms. Examples of the polar organic liquid include: dialkyl ketones and cycloalkyl ketones, such as acetone, methyl ethyl ketone, diethyl ketone, diisopropyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl ketone, methyl n-amyl ketone, and cyclohexanone; alkyl esters, such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, ethyl formate, methyl propionate, methoxypropyl acetate, and ethyl butyrate; glycols, glycol esters, and ethers, such as ethylene glycol, 2-ethoxyethanol, 3-methoxypropyl propanol, 3-ethoxypropyl propanol, 2-butoxyethyl acetate, 3-methoxypropyl acetate, 3-ethoxypropyl acetate, and 2-ethoxyethyl acetate; alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol; dialkyl ethers and cyclic ethers, such as diethyl ether and tetrahydrofuran; and combinations thereof. In one embodiment, solvents such as alcohols and alkane carboxylic acid esters can be used. The polar organic liquid can include methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol, or mixtures thereof.

[0032] In various embodiments, the composition includes at least about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or more weight percent water (and / or the solvent) based on the total weight of the composition. In other embodiments, the water (and / or the solvent) is present in an amount of about 5 to about 90 weight percent, about 5 to about 85 weight percent, about 10 to about 80 weight percent, about 15 to about 75 weight percent, about 20 to about 70 weight percent, about 25 to about 65 weight percent, about 30 to about 60 weight percent, about 35 to about 55 weight percent, about 40 to about 50 weight percent, or about 45 to about 50 weight percent, based on the total weight of the composition. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values and numerical ranges set forth above, are expressly considered to be used in this disclosure.

[0033] Binder

[0034] With respect to binders, the term "binder" generally refers to the film-forming component of the composition when the composition is, for example, a coating composition. Generally, the binder can include a polymer, oligomer, or a combination thereof, for forming a coating having desired properties (e.g., hardness, protection, adhesion, etc.). Additional components, such as carriers, pigments, catalysts, rheology modifiers, antioxidants, ultraviolet light stabilizers and absorbers, leveling agents, defoamers, anti-cratering agents, or other conventional additives, can not be included in the term "binder" unless one or more of these additional components is a film-forming component of the composition.

[0035] The film-forming component can include any water-dispersible or latex polymer that is curable. A "latex" polymer refers to a dispersion of polymer particles in water. Latex polymers generally require an auxiliary dispersant (e.g., surfactant, polymeric colloid) to form a dispersion or emulsion of polymer particles in water. A "water-dispersible" polymer refers to a polymer that is capable of being dispersed in water by itself (i.e., without the use of a separate surfactant) or water can be added to the polymer to form a stable water dispersion (i.e., the dispersion should have at least one month of shelf stability at normal storage temperatures). Such water-dispersible polymers can include nonionic or anionic functionality on the polymer that aids in its water-dispersibility. For such polymers, an external acid or base is generally used to enhance the anionic stability.

[0036] Alternatively, the binder can be selected from polyester-polyurethane polymers, latex polymers, melamine resins, and combinations thereof. It should be understood that other polymers can be included in or omitted from the composition.

[0037] Latex polymers, such as aqueous latex binders and methods for their preparation, are well known to those skilled in the art. Aqueous (meth)acrylic copolymer latex binders can generally be prepared by free radical emulsion copolymerization of ethylenically unsaturated free radical copolymerizable monomers. Typical latex binders used in paints are acrylic, vinyl-acrylic, styrene-acrylic, ethylene-vinyl acetate, vinyl acetate, alkyd, vinyl chloride, styrene-butadiene, versatic acid, vinyl acetate-maleate or mixtures thereof, as well as other binders known in the art.

[0038] The melamine resin can be partially or fully etherified using one or more alcohols, such as methanol or butanol. Hexamethoxymethyl melamine is a non-limiting example. Non-limiting examples of suitable melamine resins include monomeric melamine, polymeric melamine-formaldehyde resins, or combinations thereof. Monomeric melamine includes low molecular weight melamine having an average of more than three hydroxymethyl groups per triazine nucleus etherified with C1-C5 monohydric alcohol (e.g., methanol, n-butanol, or isobutanol), an average degree of condensation of up to about 2, in some embodiments from about 1.1 to about 1.8, and a proportion of mononuclear species of no less than about 50 weight percent. In contrast, polymeric melamine has an average degree of condensation of greater than about 1.9. Some suitable monomeric melamine includes alkylated melamine, such as methylated, butylated, isobutylated melamine, and mixtures thereof. Many such suitable monomeric melamine are commercially available.

[0039] The polyester in the polyester-polyurethane polymeric binder can be linear or branched. Useful polyesters include esterification products of aliphatic or aromatic dicarboxylic acids, polyols, diols, aromatic or aliphatic cyclic anhydrides, and cyclic alcohols. Non-limiting examples of suitable cycloaliphatic polycarboxylic acids include tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, endomethylene tetrahydrophthalic acid, tricyclodecane dicarboxylic acid, endoethylidene hexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid, and cyclobutanetetracarboxylic acid. Cycloaliphatic polycarboxylic acids can be used not only in their cis-form, but also in their trans-form, as well as in mixtures of the two forms. Further non-limiting examples of suitable polycarboxylic acids can include aromatic and aliphatic polycarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, halogenated phthalic acid (e.g., tetrachloro or tetrabromo phthalic acid), adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid, and pyromellitic acid. Combinations of polycarboxylic acids, such as combinations of polycarboxylic acids and cycloaliphatic polycarboxylic acids, are also suitable. Combinations of polyols are also suitable.

[0040] Non-limiting suitable polyols include, but are not limited to, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethyl pentanediol, ethyl butyl propylene glycol, ditrimethylolpropane, trihydroxyethyl propane, trihydroxypropyl propane, glycerol, pentaerythritol, dipentaerythritol, polyethylene glycol, and polypropylene glycol. If desired, monohydric alcohols, such as butanol, octanol, lauryl alcohol, ethoxylated or propoxylated phenol, can also be included with the polyols to control molecular weight.

[0041] Non-limiting examples of suitable polyesters include branched copolyester polymers. Compounds having multiple functionalities, such as the AxBytype (x and y each independently is 1-3), including compounds having one carboxyl group and two hydroxyl groups, two carboxyl groups and one hydroxyl group, one carboxyl group and three hydroxyl groups, or three carboxyl groups and one hydroxyl group, can be used to form branched structures. Non-limiting examples of such compounds include 2,3 dihydroxypropionic acid, 2,3 dihydroxy-2-methylpropionic acid, 2,2 dihydroxypropionic acid, 2,2-bis(hydroxymethyl)propionic acid, and the like.

[0042] The branched copolyester polymers can be conventionally polymerized from a monomer mixture including a chain extender selected from the group consisting of hydroxycarboxylic acids, hydroxycarboxylic acid lactones, and combinations thereof; and one or more branched monomers. Some suitable hydroxycarboxylic acids include glycolic acid, lactic acid, 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid, and hydroxypropionic acid. Some suitable lactones include caprolactone, valerolactone; and lactones of the corresponding hydroxycarboxylic acids such as 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid, and hydroxyvaleric acid. In some embodiments, caprolactone can be used. In various embodiments, the branched copolyester polymers can be prepared by one-step polymerization of a monomer mixture including a chain extender and a hyperbranched monomer, or by first polymerizing the hyperbranched monomer and then polymerizing the chain extender. It is understood that the branched copolyester polymers can be formed from an acrylic core with the chain extension monomers described above.

[0043] Polyester-polyurethane polymers can be prepared from a polyester and a polyisocyanate. The polyester can be a polymeric or oligomeric organic material having at least two hydroxyl functional groups or two mercapto functional groups and mixtures thereof. Polyesters and polycarbonates bearing terminal hydroxyl groups can be effectively used as diols.

[0044] Polyurethane polymers can be prepared by reacting a polyisocyanate with an excess of a polyol. In some embodiments, a low molar mass polyol (e.g., a polyhydric alcohol) defined using an empirical formula and a structural formula is used to form the polyurethane polymer. Non-limiting examples of polyols include ethylene glycol, propylene glycol, butylene glycol, hexanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethyl pentanediol, ethyl butyl propylene glycol, bis(trimethylol)propane, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, polyethylene glycol, and polypropylene glycol. In other embodiments, a low oligomeric or polymeric polyol having a number average molar mass of, for example, up to 8000, or up to 5000, or up to 2000, and / or, for example, a corresponding hydroxyl-functional polyether, polyester, or polycarbonate, is used to form the polyurethane polymer. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the values and values between the values described above, are expressly incorporated herein.

[0045] Non-limiting examples of suitable polyisocyanates include aromatic, aliphatic, or cycloaliphatic diisocyanates, triisocyanates, or tetraisocyanates, including: polyisocyanates having isocyanurate structural units, such as isocyanurates of hexamethylene diisocyanate and isocyanurates of isophorone diisocyanate; adducts of two molecules of a diisocyanate (e.g., hexamethylene diisocyanate) with a diol (e.g., ethylene glycol); uretdiones of hexamethylene diisocyanate; uretdiones of isophorone diisocyanate or isophorone diisocyanate; adducts of trimethylolpropane with m-tetramethylxylylene diisocyanate. Other polyisocyanates disclosed herein are also suitable for use in producing the polyurethane.

[0046] Aqueous polyurethane binders and methods for their preparation are known to those skilled in the art. Typical and employable non-limiting examples of aqueous polyurethane binders include aqueous polyurethane binder dispersions, which can generally be prepared by first forming an NCO-functional, hydrophilic polyurethane prepolymer by addition reaction of a polyol-based compound with a polyisocyanate, converting the formed polyurethane prepolymer into an aqueous phase, and then reacting the aqueously dispersed NCO-functional polyurethane prepolymer with an NCO-reactive chain extender (e.g., a polyamine, a hydrazine derivative, or water).

[0047] One non-limiting example of a polyester-polyurethane polymer is a polyurethane dispersion resin formed from a diol resin and a diisocyanate. Another non-limiting example of a polyester-polyurethane polymer is a polyurethane dispersion resin formed from a polycarbonate-polyester and a diisocyanate.

[0048] In some embodiments, the binder is a polymer or oligomer having crosslinkable functional groups, such as isocyanate-reactive groups. The term "crosslinkable functional group" refers to a functional group located on an oligomer, polymer, polymer backbone, polymer side chain, polymer backbone end, or a combination thereof, where the functional group is capable of crosslinking with a crosslinking functional group (in the curing step) to form a coating in a crosslinked structural form. Typical crosslinkable functional groups can include hydroxyl, thiol, isocyanate, thioisocyanate, acetoacetoxy, carboxyl, primary amine, secondary amine, epoxy, anhydride, ketimine, aldimine, or operable combinations thereof. Some other functional groups, such as orthoesters, orthocarbonates, or cyclic amides, which can produce hydroxyl or amine groups once the ring structure is opened, are also suitable as crosslinkable functional groups.

[0049] In various embodiments, the composition can include a binder in an amount of about 0.1 wt% to about 50 wt%, about 1 wt% to about 20 wt%, or about 1 wt% to about 10 wt% based on the percent of binder active. In other embodiments, the composition can include about 5 wt% to about 70 wt%, about 10 wt% to about 50 wt%, or about 15 wt% to about 25 wt% of a binder based on the percent of binder active. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values and numerical ranges set forth above, are expressly incorporated herein.

[0050] Pigment

[0051] The composition can optionally include a pigment, which can be any pigment known in the art. For example, the composition can include a pigment, and can also not include a pigment. In one embodiment, the composition is free of pigment, and can be described as a clear coat composition.

[0052] The pigments can be or include primary color pigments. Non-limiting examples of suitable primary color pigments include color matching pigments including: blue pigments including indanthrone blue (Pigment Blue 60), phthalocyanine blue (Pigment Blue 15:1, 15:2, 15:3, and 15:4), and cobalt blue (Pigment Blue 28); red pigments including quinacridone red (Pigment Red 122 and Pigment Red 202), iron oxide red (Pigment Red 101), perylene red (perylene scarlet) (Pigment Red 149, Pigment Red 177, Pigment Red 178), maroon (Pigment Red 179), azo red (Pigment Red 188), and diketopyrrolopyrrole red (Pigment Red 255 and Pigment Red 264); yellow pigments including diarylide yellow (Pigment Yellow 14), iron oxide yellow (Pigment Yellow 42), nickel titanate yellow (Pigment Yellow 53), indolinone yellow (Pigment Yellow 110 and Pigment Yellow 139), monoazo yellow (Pigment Yellow 150), bismuth vanadate yellow (Pigment Yellow 184), disazo yellow (Pigment Yellow 128 and Pigment Yellow 155); orange pigments including quinacridone orange pigments (Pigment Yellow 49 and Pigment Orange 49), benzimidazolone orange pigments (Pigment Orange 36); green pigments including phthalocyanine green (Pigment Green 7 and Pigment Green 36), cobalt green (Pigment Green 50); violet pigments including quinacridone violet (Pigment Violet 19 and Pigment Violet 42), dioxazine violet (Pigment Violet 23), and perylene violet (Pigment Violet 29); brown pigments including monoazo brown (Pigment Brown 25), chromate antimony titanate (Pigment Brown 24), iron chromium oxide (Pigment Brown 29); white pigments such as anatase and rutile titanium dioxide (Ti02) (Pigment White 6); black pigments including carbon black (Pigment Black 6 and Pigment Black 7), perylene black (Pigment Black 32), copper chromium black (Pigment Black 28).

[0053] Alternatively, the pigments can be or include special effect pigments selected from the group consisting of metallic flake pigments, mica-containing pigments, glass-containing pigments, and combinations thereof.

[0054] In other embodiments, suitable pigments are, for example, Pigment Yellow 213, Pigment Yellow 151, Pigment Yellow 93, Pigment Yellow 83, Pigment Red 122, Pigment Red 168, Pigment Red 254, Pigment Red 179, Pigment Red 166, Pigment Red 48:2, Pigment Violet 19, Pigment Blue 15:1, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Black 7, or Pigment White 6.

[0055] Further non-limiting examples of suitable pigments include metal oxides, metal hydroxides, special effect pigments (including metallic flake), chromates (e.g., lead chromate), sulfides, sulfates, carbonates, carbon black, silica, talc, china clay, phthalocyanine blue and phthalocyanine green, organic reds, organic maroons, pearlescent pigments, other organic pigments and dyes, and combinations thereof. If desired, pigments that do not contain chromates can also be used, such as barium metaborate, zinc phosphate, aluminum triphosphate, and combinations thereof.

[0056] Further non-limiting examples of suitable effect pigments include: bright aluminum flake, very fine aluminum flake, medium particle size aluminum flake, and bright medium coarse aluminum flake; mica flake coated with titanium dioxide pigments, also known as pearlescent pigments; and combinations thereof. Non-limiting examples of suitable color pigments include titanium dioxide, zinc oxide, iron oxide, carbon black, monoazo red toner, red iron oxide, quinacridone maroon, transparent red oxide, dioxazine carbazole violet, iron blue, indanthrone blue, chromium titanate, titanium yellow, monoazo permanent orange, iron yellow, monoazo benzimidazolone yellow, transparent yellow oxide, isoindoline yellow, isoindoline yellow, tetra-chloro isoindoline yellow, anthraquinone orange, lead chromate yellow, phthalocyanine green, quinacridone red, perylene maroon, quinacridone violet, pre-darkened chromium yellow, sulfur indigo red, transparent red oxide flake, molybdate orange, molybdate orange-red, and combinations thereof. As is well known in the art, various grades and having various coatings of titanium dioxide are commercially available. Any one of these can be used herein.

[0057] Extender pigments can also be used. Extender pigments can have various configurations, including but not limited to nodular, flaky, acicular, and fibrous. Non-limiting examples of suitable extender pigments include chalk, barite, amorphous silica, fumed silica, diatomaceous earth, china clay, calcium carbonate, phyllosilicates (mica), wollastonite, magnesium silicate (talc), barium sulfate, kaolin, and aluminum silicate.

[0058] The composition can include a pigment, if included, in an amount greater than zero, for example, from about 0.1 to about 50 wt.%, from about 1 to about 20 wt.%, or from about 1 to about 10 wt.%, based on the total weight of the composition. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values falling within the ranges recited above, are expressly contemplated for use herein.

[0059] Particles

[0060] Now turning to the particle itself, the particle can alternatively be described as a core-shell polymer. The core-shell polymer can include any of the polymers or copolymers described herein. In the context of the present disclosure, the term “(co)polymer” means either a polymer or a copolymer. The term “polymer” and the term “copolymer” can be used interchangeably herein, as understood by one of skill in the art.

[0061] As used herein and throughout the specification, the terms "core-shell morphology," "core-shell structure," "core polymer," "staged core polymer," and "two-stage polymer" or "multi-stage polymer" can be used interchangeably and mean a polymer or polymer particle prepared by a sequential or staged polymerization process in which the monomeric repeat units of each sequence or stage are added to a polymerization reactor in a batch or continuous process and polymerization is initiated, which can be before or concurrently with the addition and initiation of polymerization of the repeat units of a subsequent sequence or stage. In some embodiments, polymerization of one stage will be substantially complete before the monomers of the next stage are added to the polymerization reactor. In other embodiments, polymerization of one stage can be only partially complete before the monomers of the next stage are added to the polymerization reactor.

[0062] The particles themselves comprise at least one core polymer and at least one shell polymer disposed around the at least one core polymer. The at least one core polymer is the polymerization reaction product of a first monomer mixture. The first monomer mixture comprises: al) optionally one or more anionic ethylenically unsaturated monomers; bl) optionally one or more short chain hydrophobic ethylenically unsaturated monomers having a hydrophobic group in the side chain comprising 7 or fewer carbon atoms; cl) optionally one or more associative monomers; dl) optionally one or more crosslinking monomers; el) optionally one or more non-ionic ethylenically unsaturated monomers; and fl) optionally one or more long chain hydrophobic ethylenically unsaturated monomers having a hydrophobic group in the side chain comprising 8 or more carbon atoms. In this first monomer mixture, if al) is not present, then el) is present in the first monomer mixture. Further, if fl) is not present in the first monomer mixture, then al) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the first monomer mixture. Still further, if fl) is present in the first monomer mixture, then al) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the first monomer mixture. However, at least one of bl) and fl) is present in the first monomer mixture. Now directed to the at least one shell polymer, the at least one shell polymer is at least partially crosslinked and is the polymerization reaction product of a second monomer mixture. The second monomer mixture comprises: a2) optionally one or more anionic ethylenically unsaturated monomers; b2) optionally one or more short chain hydrophobic ethylenically unsaturated monomers having a hydrophobic group in the side chain comprising 7 or fewer carbon atoms; c2) optionally one or more associative monomers; d2) one or more crosslinking monomers; e2) optionally one or more non-ionic ethylenically unsaturated monomers; and f2) optionally one or more long chain hydrophobic ethylenically unsaturated monomers having a hydrophobic group in the side chain comprising 8 or more carbon atoms. In this second monomer mixture, if a2) is not present, then e2) is present in the second monomer mixture. Further, if f2) is not present in the second monomer mixture, then a2) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the second monomer mixture. Still further, if f2) is present in the second monomer mixture, then a2) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the second monomer mixture. Additionally, at least one of b2) and f2) is present in the second monomer mixture, while at least one of the first monomer mixture and the second monomer mixture comprises greater than 0 mol% of al) or a2), respectively.

[0063] At least one shell polymer

[0064] The at least one shell polymer can be disposed all around the at least one core polymer or only around a portion thereof, for example, disposed around about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% or more of the outer surface of the at least one core polymer. For example, the particles can be in a form in which the core portion (e.g., core polymer) is completely coated or encapsulated by the shell portion (e.g., shell polymer), or incompletely coated or encapsulated. It is also to be understood that in describing "core polymer" and "shell polymer," there can be a significant amount of interpenetration of these polymers. Thus, the "core polymer" can extend to some degree into the at least one shell polymer, and vice versa. The terms "core polymer" and "shell polymer" and like terms are used herein to generally describe the polymeric materials, and are not intended to strictly identify any particular polymer as a "shell" or as a "core" polymer. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values and ranges stated above, are expressly incorporated herein.

[0065] In various embodiments, the core-shell polymer has a structure in which one or more polymers forming a core portion, sequence, or stage (e.g., core polymer) and one or more polymers forming a shell portion, sequence, or stage (e.g., shell polymer) are bonded and / or attracted to one another by physical and / or chemical means. The structure and / or chemical composition (e.g., monomer mixture and / or amounts used) of the core-shell polymer can vary from the inside to the outside (i.e., from the at least one core polymer to the at least one shell polymer), possibly forming gradient regions having different physical and chemical properties from one another. These gradient regions can be gradual, forming a morphology having a gradient of polymer structure or composition in any radial direction therefrom. Alternatively, the gradient regions can be relatively distinct, forming a morphology having a relatively distinct core portion (comprising one polymer composition) and a relatively distinct shell portion (comprising a different polymer composition) when moving radially outward from the center of the core-shell polymer. The term "gradient" generally describes a pattern having a gradual change (e.g., increase or decrease) in a particular characteristic. For example, the core-shell polymer can vary with a gradual change in a physical and / or chemical property (e.g., amount of crosslinking) when considered from the inside to the outside or from the outside to the inside.

[0066] The core-shell morphology can comprise multiple layers or regions of different polymer compositions. The rate of change in the polymeric morphology is not particularly critical as long as the polymers exhibit the desired physical properties described herein. Thus, as used in various embodiments, the terms "core" and "shell" refer to the polymeric content inside and outside, respectively, of the core-shell polymer, and the use of these terms should not be interpreted to mean that the core-shell polymer necessarily exhibits a distinct interface between the inside and outside polymers.

[0067] The core-shell polymer can comprise one or more core polymers and one or more shell polymers, which can be the same or different from the at least one core polymer in terms of the type and ratio of monomers forming the polymer backbone, and can also differ from each other.

[0068] In various embodiments, one or both of the at least one core polymer and the at least one shell polymer comprises a gradient of increasing crosslinking density as measured outwardly from the center of the at least one core polymer toward the at least one shell polymer, wherein the crosslinking density of the at least one core polymer is less than the crosslinking density of the at least one shell polymer.

[0069] Alternatively, one or both of the at least one core polymer and the at least one shell polymer comprises a gradient of increasing crosslinking density as measured inwardly from the outermost layer of the at least one shell polymer toward the center of the at least one core polymer, wherein the crosslinking density of the at least one core polymer is greater than the crosslinking density of the at least one shell polymer.

[0070] The core-shell polymer can be present in the composition in any amount. Typically, the core-shell polymer is present in an amount of from about 0.01 to about 10 weight percent, from about 0.05 to about 2 weight percent, or from about 0.1 to about 2 weight percent, based on the total weight of the composition. In other embodiments, the amount is from about 0.1 to about 1.9, from about 0.2 to about 1.8, from about 0.3 to about 1.7, from about 0.4 to about 1.6, from about 0.5 to about 1.5, from about 0.6 to about 1.4, from about 0.7 to about 1.3, from about 0.8 to about 1.2, from about 0.9 to about 1.1, or about 1 weight percent, based on the total weight of the composition. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values described above and numerical values falling within the ranges described above, are expressly contemplated for use.

[0071] At least one core polymer

[0072] Referring now to the at least one core polymer itself, the at least one core polymer is independent of the at least one shell polymer. The term "at least one" means that a single core polymer can be used. Alternatively, more than one core polymer can be used. For example, one or more seed polymers can be used, which are subsequently partially or completely encapsulated by one or more other polymers, where the entire complex of the seed polymer and the encapsulating polymer can be referred to as a "core" polymer. Any one or more of these seed polymers and / or encapsulating polymers can be any polymer described herein. Alternatively, the at least one core polymer can be a single core polymer.

[0073] The at least one core polymer can comprise, consist, or consist essentially of, a polymerized reaction product of the monomers in the first monomer mixture as first mentioned above. For example, the monomers used to form the at least one core polymer can be selected from a), b), c), d), e), f), and combinations thereof. In one embodiment, only a) and b) are used to form the at least one core polymer. In other embodiments, the following combinations are used: (a, b, c); (a, b, c, d); (a, b, d); (a, b, c, d, e); (a, b, e); (a, b, c, e); (a, b, d, e); (a, b, c, f); (a, b, c, d, f); (a, b, d, f); (a, b, c, d, e, f); (a, b, e, f); (a, b, c, e, f); (a, b, d, e, f); (a, b, f); (a, c, f); (a, d, f); (a, e, f); (a, b, c, f); (a, b, d, f); (a, b, e, f); and all combinations thereof. Any one or more of c, d, e, and f can be used or omitted.

[0074] As used herein, the monomers generally described for the first monomer mixture are labeled as a1), b1), c1), d1), e1), and f1). The nomenclature "1" indicates that the monomers can be included in the first monomer mixture. Similarly, as described in more detail below, the monomers generally described for the second monomer mixture are labeled as a2), b2), c2), d2), e2), and f2). The nomenclature "2" indicates that the monomers can be included in the second monomer mixture. But the general nomenclature and options described herein with respect to selecting a, b, c, d, e, and f apply to the "1" and "2" designations. For example, consider that any of a1) and a2) can be any monomer described herein as "a", any of b1) and b2) can be any monomer described herein as "b", any of c1) and c2) can be any monomer described herein as "c", any of d1) and d2) can be any monomer described herein as "d", any of e1) and e2) can be any monomer described herein as "e", and any of f1) and f2) can be any monomer described herein as "f". Moreover, consider that the following descriptions also apply to the second monomer mixture in various non-limiting embodiments.

[0075] With respect to the first monomer mixture, if a1) is not present in the first monomer mixture, then e1) is present in the first monomer mixture. This is because certain hydrophilic monomers are needed to swell the particles.

[0076] Further, if f1) is not present in the first monomer mixture, a1) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the first monomer mixture. For example, the amount can be about 5 to about 55, about 10 to about 50, about 15 to about 45, about 20 to about 40, about 25 to about 35, or about 30 to about 35 mol%. In other embodiments, the monomer mixture comprises about 12 to about 60 mol% of a1) based on the total moles of monomers. In other embodiments, the amount of a1) is greater than about 0 to about 10, about 1 to about 9, about 2 to about 8, about 3 to about 7, about 4 to about 6, or about 4 to about 5 mol% based on the total moles of monomers. In various embodiments, the amount is about 15 to about 60, about 20 to about 55, about 25 to about 50, about 30 to about 45, or about 35 to about 40 mol% based on the total moles of monomers. This is because stable emulsions cannot be formed if a1) greatly exceeds 60 mol% when f1 is not present. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values falling within the ranges recited above, are expressly contemplated for use.

[0077] Further, if f1) is present in the first monomer mixture, a1) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the first monomer mixture. For example, the amount can be about 5 to about 75, about 10 to about 70, about 15 to about 65, about 20 to about 60, about 25 to about 55, about 30 to about 50, about 35 to about 45, or about 35 to about 40 mol%. In other embodiments, the amount of a1) is greater than about 0 to about 10, about 1 to about 9, about 2 to about 8, about 3 to about 7, about 4 to about 6, or about 4 to about 5 mol% based on the total moles of monomers in the first monomer mixture. This is because f1 provides a high level of hydrophobicity, which is advantageous for forming stable emulsions. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values falling within the ranges recited above, are expressly contemplated for use.

[0078] Further, at least one of b1) and f1) is present in the first monomer mixture. This is because a hydrophobic monomer is needed to form the emulsion.

[0079] a) Anionic ethylenically unsaturated monomer

[0080] As described above, a) anionic ethylenically unsaturated monomer can describe a1) and / or a2). As used herein, the term "anionic ethylenically unsaturated monomer" refers to an ethylenically unsaturated monomer from which a polymer produced is capable of producing a negative charge in aqueous solution, and which is not an associative monomer as described below. One or more of a1) and / or a2) can be used as described above.

[0081] In various embodiments, the anionic ethylenically unsaturated monomer is an acid. The anionic ethylenically unsaturated monomer can include, but is not limited to, acrylic acid, methacrylic acid, 2-ethyl acrylic acid, α-chloroacrylic acid, α-cyanoacrylic acid, β-methyl acrylic acid (tiglic acid), α-phenylacrylic acid, β-acryloxypropionic acid, sorbic acid, α-chlorosorbic acid, angelic acid, 2-carboxyethyl (meth) acrylate, cinnamic acid, p-chlorocinnamic acid, β-styrylacrylic acid (1-carboxy-4-phenylbutadiene-1,3), itaconic acid, maleic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, fumaric acid, tricarboxyethylene, muconic acid, 2-acryloyloxypropionic acid, 2-acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, sodium methallyl sulfonate, sulfonated styrene, allyloxybenzenesulfonic acid, and vinyl phosphonic acid. Combinations of anionic ethylenically unsaturated monomers can also be used. In one embodiment, the anionic ethylenically unsaturated monomer can be methacrylic acid, maleic acid, acrylic acid, itaconic acid, 2-acrylamido-2-methylpropane sulfonic acid, or a mixture thereof. In one embodiment, most commonly, the anionic ethylenically unsaturated monomer is methacrylic acid or acrylic acid, or a combination thereof. As used herein, the term "(meth)acrylic acid" is meant to include both acrylic acid and methacrylic acid. Similarly, the term "(meth)acrylic acid alkyl ester" is meant to include both acrylic acid alkyl ester and methacrylic acid alkyl ester. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values and ranges set forth above, are expressly incorporated herein.

[0082] b) Short chain hydrophobic ethylenically unsaturated monomer

[0083] As described above, b) short chain hydrophobic ethylenically unsaturated monomer can describe b1) and / or b2). As used herein, the term "short chain hydrophobic ethylenically unsaturated monomer" refers to a monomer whose side chain includes a hydrophobic group having 7 or fewer carbon atoms (e.g., 7, 6, 5, 4, 3, 2, or 1 carbon atom). The monomer is hydrophobic and tends to form an emulsion system when reacted with an anionic ethylenically unsaturated monomer. One or more of the following can be used as described above.

[0084] In various embodiments, the hydrophobic ethylenically unsaturated monomer can be sparingly soluble in water, having a solubility of less than about 6, 5, 4, 3, 2, 1.6, 1, etc. grams in about 100 milliliters of water at about 25°C. These hydrophobic ethylenically unsaturated monomers can include linear or branched alk(en)yl, cycloalkyl, aryl, or alk(en)aryl moieties.

[0085] Suitable hydrophobic ethylenically unsaturated monomers include C1-C7 alkyl esters of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; C1-C7 alkyl amides of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; benzyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate ethoxylate, phenyl (meth)acrylate ethoxylate, 6-hydroxyhexyl (meth)acrylate, and styrene, a-methylstyrene, vinyltoluene, and p-chlorostyrene; vinyl acetate, vinyl butyrate, vinyl hexanoate, vinyl valerate, vinyl hexanoate, vinyl caprolactam, (meth)acrylonitrile, isobutylene, diisobutylene, isoprene, vinyl chloride, vinylidene chloride, and combinations thereof.

[0086] In one embodiment, the amount of b1 ) hydrophobic ethylenically unsaturated monomer is used such that the sum of the amounts of a1 ) and b1 ) is about 100 mol%. In various embodiments, the amount of b1 ) is about 1 to about 99, about 5 to about 95, about 10 to about 90, about 10 to about 88, about 10 to about 85, about 15 to about 80, about 20 to about 75, about 25 to about 70, about 30 to about 65, about 35 to about 60, about 40 to about 55, or about 45 to about 50 mol%, based on the total moles of monomers in the above-described first monomer mixture (typically not including the amount of any crosslinking monomer or agent used). In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the above-mentioned numerical values and numerical values falling between the above-mentioned numerical values, are expressly considered to be used herein.

[0087] c) Associative monomer

[0088] As described above, c) associative monomer can describe c1 ) and / or c2). Herein, "associative monomer" describes an ethylenically unsaturated monomer that includes a hydrophobic group and a spacer moiety that keeps the hydrophobic group at a sufficient distance from the backbone of the core or shell polymer so as to form hydrophobic associations in aqueous solution, and wherein the hydrophobic group includes at least six carbon atoms. The spacer moiety is typically an ethoxylate group, but any other group that extends the hydrophobic group away from the backbone of the core and / or shell polymer can also be used. One or more of the following can be used as described above:

[0089] Spaced hydrophobes can include, but are not limited to, alcohol ethoxylates, alkylphenol ethoxylates, propoxy / butoxy ethoxylates, ethoxylated siloxanes, and the like. In one embodiment, typical spaced hydrophobes include alcohol ethoxylates and / or alkylphenol ethoxylates. In another embodiment, the alcohol ethoxylates have a carbon chain length of from about 6 to about 40 carbons and an ethoxylate degree of from about 6 to about 100 moles. In yet another embodiment, the alcohol ethoxylates have a carbon chain length of from about 12 to about 22 carbons and an ethoxylate degree of from about 15 to about 30 moles. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values and numerical ranges set forth above, are expressly considered as being used in this disclosure.

[0090] The hydrophobe can be a linear or branched alk(en)yl, cycloalkyl, aryl, alk(en)aryl, or alkoxylated derivative thereof. In one embodiment, the most common hydrophobe is a linear or branched alcohol and amine comprising from about 12 to about 32 carbons. The associative monomer can comprise an ethylenically unsaturated monomer covalently linked to the hydrophobe. In one embodiment, the ethylenically unsaturated monomer portion of the associative monomer is typically a (meth)acrylate, itaconate, and / or maleate comprising an ester linkage. But the associative monomer can also comprise amides, ureas, urethanes, ethers, alkyls, aryls, and other suitable linking groups. The hydrophobe can be an alkyl amine or dialkyl amine ethoxylate. In one embodiment, (meth)acrylate groups are most typical. In another embodiment, typical associative monomers are C 12-32 (EO) 10-30 (meth)acrylate or C 12-32 (EO) 10-30 (meth)acrylate or C 12-32 (EO) 10-30 (meth)acrylate or C

[0091] In one embodiment, the associative monomer has the structure of Formula (I):

[0092]

[0093] wherein:

[0094] R1is selected from -H, -CH3, -COOH, or -CH2COOH;

[0095] A is selected from the group consisting of -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH2C(O)N-, -C(O)N-, -CH2-, -O-C(O)-, -NHC(O)O-, -NHC(O)NH-, -C6H4(R5)-NH-C(O)-O-, -C6H4(R5)-NH-C(O)-NH-, -C(O)O-CH2-CH(CH2OH)-O-, -C(O)O-CH2-CH(CH2OH)-NH-, -C(O)O-CH2-CH-CH2(OH)-O-, -C(O)O-CH2-CH-CH2(OH)-NH-, -CH2-O-CH2-CH(CH2OH)-O-, -CH2-O-CH2-CH-CH2(OH)-O-, -CH2-O-CH2-CH(CH2OH)-NH-, and -CH2-O-CH2-CH-CH2(OH)-NH-;

[0096] (R3-O) n R3 is a polyoxyalkylene, which is a homopolymer, random copolymer or block copolymer of C2-C4oxyalkylene units, wherein each R3 is independently selected from -C2H4-, -C3H6-, -C4H8- or mixtures thereof, and n is an integer from about 5 to about 250, typically n is from about 5 to about 100, more typically from about 10 to about 50, and most typically from about 15 to about 30; R4 is selected from C6-C 36 a linear or branched, saturated or unsaturated alk(en)yl or alk(en)aryl group, typically a C8-C 32 a linear or branched alk(en)yl group, more typically a C 10 -C 22 a linear alk(en)yl group or C 10 -C 32 a branched alk(en)yl group; and R5 is -CH2- or -(C)(CH3)2-. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the values and values falling between the values above, are explicitly contemplated herein.

[0097] Suitable associative monomers include methacrylates and itaconates of hydrophilic ethoxylate chains with hydrophobic alkyl chains.

[0098] In one embodiment, the associative monomer is an ethoxylated alkyl methacrylate having the structure of Formula I(A):

[0099]

[0100] In one embodiment, the associative monomer is an itaconic acid based associative monomer, such as a cetylethoxylate itaconate (cetylethoxylate itaconate), a behenylethoxylate itaconate (behenylethoxylate itaconate), or a stearyl ethoxylate itaconate (stearyl ethoxylate itaconate) having the structure of Formula I (B, C, D, respectively):

[0101]

[0102] In various embodiments, the associative monomer is used in an amount of about 0.01 mol% to about 3 mol%, or about 0.05 mol% to about 2 mol%, or about 0.1 mol% to about 1 mol%, based on the total moles of monomer mixture. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the values noted above and values between the values noted above, are expressly considered for use herein.

[0103] In various embodiments, the at least one core polymer and / or the at least one shell polymer is free of residues of the one or more optional associative monomers. In other words, no associative monomers are used in such embodiments. For example, one or more of the c1) and c2) associative monomers can be absent from the first and / or second monomer mixture.

[0104] d) Crosslinking monomer (crosslinker)

[0105] As noted above, the d) crosslinking monomer can describe d1) and / or d2). For crosslinking monomers, one or more can be used as described above. Alternatively, these monomers can be omitted. In various embodiments, the at least one core polymer is not crosslinked. However, some crosslinking can be employed so long as the amount of crosslinking does not unduly inhibit the ability of the core-shell polymer to swell as described herein.

[0106] In one embodiment, the at least one shell polymer is formed using a crosslinking monomer / reagent, while the at least one core polymer is not. Alternatively, both the at least one shell polymer and the at least one core polymer can be formed using a crosslinking monomer / reagent. However, if the amount of crosslinking agent is the same in both polymers, a conventional polymer is typically formed rather than a core-shell polymer of the present disclosure.

[0107] Generally, when crosslinking monomers / agents are used, the polymer formed therefrom is or comprises a partially or substantially crosslinked network. In one embodiment, the crosslinking monomers / agents are used to form the at least one core polymer such that it is a partially or substantially crosslinked network, provided that the mole percent of crosslinking monomers / agents used to form the at least one core polymer is less than the mole percent of crosslinking monomers / agents used to form the at least one shell polymer.

[0108] For example, in various embodiments, the at least one core polymer comprises an amount of residues of one or more crosslinking monomers that is about 5 mol% or less than the amount of residues of one or more crosslinking monomers in the shell. In other words, the amount of crosslinking monomers / agents used to form the at least one core polymer can be about 5 mol% less than the amount of crosslinking monomers / agents used to form the at least one shell polymer. In other embodiments, the amount is about 5 to about 10 mol% less. In other embodiments, the amount is about 5, 4, 3, 2, 1, or even 0.5 mol% less. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the values noted above and values between the values noted above, are expressly considered for use herein.

[0109] The crosslinking monomers / agents can be selected from one or more of the following: crosslinking monomers having two or more carbon-carbon double bonds, multifunctional crosslinking compounds that react with pendant functional groups on the associated polymer, and combinations thereof.

[0110] Exemplary crosslinking monomers / agents include: di(meth)acrylate compounds such as ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,6-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 2,2'-bis(4-(propenyloxy-propyloxyphenyl)propane, 2,2'-bis(4-(propenyloxydiethoxy-phenyl)propane, and zinc acrylate (i.e., 2(C3H3O2)Zn ++) ; tri(meth)acrylate compounds such as trimethylolpropane tri(meth)acrylate, trimethyloloethane tri(meth)acrylate, trimethyl(ethoxylate)propane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; tetra(meth)acrylate compounds such as di(trimethylolpropane)tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; hexa(meth)acrylate compounds such as dipentaerythritol hexa(meth)acrylate; allyl compounds such as allyl (meth)acrylate, diallyl phthalate, diallyl itaconate, diallyl fumarate, and diallyl maleate; sucrose polyallyl ethers having 2 to 8 alkyl groups per molecule, polyallyl ethers of pentaerythritol such as pentaerythritol diallyl ether, pentaerythritol triallyl ether, and pentaerythritol tetraallyl ether; polyallyl ethers of trimethylolpropane such as trimethylolpropane diallyl ether and trimethylolpropane triallyl ether; and combinations thereof. Other suitable compounds include divinyl glycol, divinyl benzene, and N,N'-methylenebisacrylamide, and combinations thereof. In another embodiment, suitable monomers can be synthesized by esterification of a polyol made from ethylene oxide or propylene oxide or combinations thereof with an unsaturated anhydride such as maleic anhydride, citraconic anhydride, itaconic anhydride, or by addition reaction with an unsaturated isocyanate such as 3-isopropenyl-alpha, alpha-dimethylphenyl isocyanate.

[0111] Exemplary multifunctional crosslinking monomers / agents include: polyhaloalcohols such as 1,3-dichloroisopropyl alcohol and 1,3-dibromo isopropyl alcohol; sulfonium zwitterions such as tetrahydrothiophene adducts of novolac resins; halogenated alkylene oxides such as epichlorohydrin, epoxy bromopropane, 2-methyl epichlorohydrin, and epoxy iodopropane; polyglycidyl ethers such as 1,4-butanediol diglycidyl ether, glycerol-1,3-diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, bisphenol A-epichlorohydrin epoxy resin, and mixtures of the foregoing.

[0112] e) Non-ionic ethylenically unsaturated monomer

[0113] As noted above, e) non-ionic ethylenically unsaturated monomers can describe ei) and / or e2). The term "non-ionic ethylenically unsaturated monomer" as used herein means an ethylenically unsaturated monomer that does not introduce a charge into the polymer in which it is formed, and which is neither a hydrophobic ethylenically unsaturated monomer nor an associative monomer or crosslinker each as described herein. As noted above, one or more can be used, or none can be omitted.

[0114] In various embodiments, the non-ionic ethylenically unsaturated monomers include, but are not limited to, acrylamides, methacrylamides, N-C1-C3 alkyl (meth)acrylamides, and N,N-C1-C3 dialkyl (meth)acrylamides, such as N-methyl methacrylamide, N-ethyl acrylamide, N-propyl acrylamide, N-isopropyl acrylamide, N,N-dimethyl acrylamide, and N,N-dimethyl methacrylamide; vinyl morpholin, vinyl pyrrolidone, vinyl propionate, vinyl butyrate; ethoxylated alkyl, alkaryl, or aryl monomers, such as methoxypolyethylene glycol (meth)acrylate, allyl glycidyl ether, allyl alcohol, glyceryl (meth)acrylate, C1-C4 hydroxyalkyl esters of (meth)acrylic acid, and the like. The non-ionic ethylenically unsaturated monomers include: (poly)C1-C4 alkoxylated (meth)acrylates, such as poly(ethylene glycol) n (meth)acrylates and poly(propylene glycol) n (meth)acrylates, where n = 1-100, typically 3-50, most typically 5-20; ethoxylated C1-C4 alkyl, C1-C4 alkaryl, or aryl monomers. In one embodiment, the monomer is methoxypolyethylene glycol (meth)acrylate. Optional C1-C4 (meth)acrylic acid hydroxyalkyl esters can include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and butanediol mono(meth)acrylate. In one embodiment, the monomer is selected from 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the values noted above and values between the values noted above, are expressly contemplated for use herein.

[0115] In one embodiment, the optional non-ionic ethylenically unsaturated monomer is used in an amount of about 0 to about 85, about 1 to about 85, about 10 to about 85, about 15 to about 80, about 20 to about 75, about 25 to about 70, about 30 to about 65, about 35 to about 60, about 40 to about 55, or about 45 to about 50 mol%, based on the total moles of monomers in the monomer mixture described above (typically not including the amount of any crosslinking monomer / agent used). In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the values noted above and values between the values noted above, are expressly contemplated for use herein.

[0116] f) Long chain hydrophobic ethylenically unsaturated monomer

[0117] As described above, f) long chain hydrophobic ethylenically unsaturated monomers can describe f1) and / or f2). The one or more long chain hydrophobic ethylenically unsaturated monomers have a side chain comprising a hydrophobic group of 8 or more carbon atoms. While there is no specific upper limit on the number of carbon atoms, in various embodiments, the upper limit is about 50, 45, 40, 35, 30, 25, 20, 15, or 10. In other embodiments, the number of carbon atoms is from about 8 to about 32, 10 to about 30, 12 to about 28, 14 to about 26, 16 to about 24, 18 to about 22, or 20 to about 22. In various embodiments, such monomers are independently selected from the group consisting of C8-C32 alkyl esters of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; C8-C32 alkyl amides of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; 10-hydroxydecyl (meth)acrylate, t-butyl styrene, isopropyl styrene, octyl vinylate, nonyl vinylate, decyl vinylate, neodecyl vinylate, lauryl vinylate, vinyl caprolactam, (meth)acrylonitrile, isobutylene, diisobutylene, isoprene, chloroethylene, vinylidene chloride, 1-allylnaphthalene, 2-allylnaphthalene, 1-vinylnaphthalene, 2-vinylnaphthalene; and combinations thereof. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values described above and numerical values falling within the ranges described above, are expressly considered to be used herein.

[0118] In other embodiments, in view of the above definitions of such monomers, b1) and / or b2) and / or f1) and / or f2) can be selected from the following, as appropriate: C1-C 32 alkyl esters of (meth)acrylic acid, including methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, benzyl ethoxy (meth)acrylate, phenyl ethoxy (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-butyloctyl (meth)acrylate, 2-hexyldecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, 2-decyldodecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, behenyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate; and C4-C 32alkyl amides, including t-butyl (meth)acrylamide, t-octyl (meth)acrylamide, 2- ethylhexyl (meth)acrylamide, n-octyl (meth)acrylamide, dodecyl (meth)acrylamide, octadecyl (meth)acrylamide, and docosyl (meth)acrylamide; styrene, a- methylstyrene, vinyltoluene, t-butylstyrene, isopropylstyrene, and p-chlorostyrene; vinyl acetate, vinyl butyrate, vinyl hexanoate, vinyl valerate, vinyl hexanoate, vinyl octanoate, vinyl nonanoate, vinyl decanoate, vinyl neodecanoate, vinyl laurate, vinyl caprolactam, (meth)acrylonitrile, butadiene, isobutylene, isoprene, vinyl chloride, vinylidene chloride, 1-allylnaphthalene, 2-allylnaphthalene, 1-vinylnaphthalene, 2-vinylnaphthalene, (meth)acrylic acid ethyl ester, (meth)acrylic acid methyl ester, 2-ethylhexyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, vinyl acetate, t-butyl acrylamide; and combinations thereof. In various embodiments, typically ethyl acrylate, methyl acrylate, methyl methacrylate, vinyl acetate, butyl acrylate, and combinations thereof. In other embodiments, exemplary alkyl (meth)acrylate monomers can be selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, and combinations thereof. In one embodiment, ethyl acrylate is typical.

[0119] In various embodiments, the amount of f1) long chain hydrophobic ethylenically unsaturated monomer is about 1 to about 99, about 5 to about 95, about 10 to about 90, about 10 to about 88, about 10 to about 85, about 15 to about 80, about 20 to about 75, about 25 to about 70, about 30 to about 65, about 35 to about 60, about 40 to about 55, or about 45 to about 50 mol% based on the total moles of monomers in the first monomer mixture described above (typically not including the amount of any crosslinking monomer or agent used).

[0120] Shell polymer

[0121] With respect to the at least one shell polymer, the at least one shell polymer is independently a polymerization reaction product of a second monomer mixture comprising: a2) optionally one or more anionic ethylenically unsaturated monomers; b2) optionally one or more short chain hydrophobic ethylenically unsaturated monomers (which pendant chain comprises a hydrophobic group having 7 or fewer carbon atoms); c2) optionally one or more associative monomers; d2) one or more crosslinking monomers; e2) optionally one or more nonionic ethylenically unsaturated monomers; and f2) optionally one or more long chain hydrophobic ethylenically unsaturated monomers (which pendant chain comprises a hydrophobic group having 8 or more carbon atoms). In other words, any of the components described above can be used to form the at least one shell polymer.

[0122] It is contemplated that any of the above descriptions regarding the components or amounts thereof used to form the at least one core polymer can also apply to the at least one shell polymer in various non-limiting embodiments. Further, the amounts of any one or more of any of a1) - f1) above can also independently apply to any one or more of a2) - f2) in the second monomer mixture, where the weight basis would be the second monomer mixture.

[0123] For example, the monomers used to form the at least one shell polymer can be selected from a), b), c), d), e), f), and combinations thereof. In one embodiment, only a) and b) are used to form the at least one core polymer. In other embodiments, the following combinations are used: (a, b, c); (a, b, c, d); (a, b, d); (a, b, c, d, e); (a, b, e); (a, b, c, e); (a, b, d, e); (a, b, c, f); (a, b, c, d, f); (a, b, d, f); (a, b, c, d, e, f); (a, b, e, f); (a, b, c, e, f); (a, b, d, e, f); (a, b, f); (a, c, f); (a, d, f); (a, e, f); (a, b, c, f); (a, b, d, f); (a, b, e, f); and all combinations thereof. In various non-limiting embodiments, any one or more of c, d, e, and f can be used or omitted.

[0124] In various embodiments, the at least one shell polymer is at least partially crosslinked and comprises about 0.01 mol% to about 10 mol% of residues of one or more crosslinking monomers. In various embodiments, the amount is about 0.05 to about 10, about 0.1 to about 10, about 1 to about 10, about 0.01 to about 0.1, about 0.05 to about 0.1, about 0.1 to about 1 mol%, etc. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values described above and numerical values between the numerical values described above, are expressly contemplated for use herein.

[0125] In various embodiments, the one or more shell polymers can have any mole percent of crosslinker residues, so long as the at least one core polymer has a mole percent of crosslinker residues that is less than the at least one shell polymer.

[0126] In one embodiment, the residue of the one or more optional associative monomers is present in the at least one core polymer and / or the at least one shell polymer in an amount greater than zero and up to about 1.5 mol%, for example, about 0.05 to about 1.5, about 0.1 to about 1.5, about 0.5 to about 1.5, about 0.5 to about 1, or about 0.1 to about 0.15 mol%. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly contemplated for use herein.

[0127] In other embodiments, the at least one shell polymer is at least partially crosslinked and comprises from about 0.01 mol% to about 10 mol% of residues of the one or more crosslinking monomers. In various embodiments, the amount is about 0.05 to about 10, about 0.1 to about 10, about 1 to about 10, about 0.01 to about 0.1, about 0.05 to about 0.1, about 0.1 to about 1 mol%, and the like. In other embodiments, the amount is about 0.1 to about 2.8, about 0.2 to about 2.7, about 0.3 to about 2.6, about 0.4 to about 2.5, about 0.5 to about 2.4, about 0.6 to about 2.3, about 0.7 to about 2.2, about 0.8 to about 2.1, about 0.9 to about 2, about 1 to about 1.9, about 1.1 to about 1.8, about 1.2 to about 1.7, about 1.3 to about 1.6, or about 1.4 to about 1.5 mol%. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly contemplated for use herein.

[0128] In other embodiments, the at least one core polymer comprises from about zero mol% of residues of the one or more crosslinking monomers up to an amount that is less than about 25 mol% of the amount of residues of the one or more crosslinking monomers present in the at least one shell polymer. In various embodiments, the amount is about 0.05 to about 25, about 0.1 to about 25, about 1 to about 25, about 0.01 to about 0.1, about 0.05 to about 0.1, about 0.1 to about 1 mol%, and the like. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly contemplated for use herein.

[0129] In other embodiments, the at least one core polymer comprises about zero mole percent of residues of the one or more crosslinking monomers, and the at least one shell polymer comprises greater than zero mole percent of residues of the one or more associative monomers. The amount can be any amount greater than zero. For example, the amount can be from about 0.05 to about 100, from about 0.1 to about 100, from about 1 to about 100, from about 0.01 to about 0.1, from about 0.05 to about 0.1, from about 0.1 to about 1 mole percent, or the like. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly incorporated herein.

[0130] In other embodiments, the at least one core polymer comprises about zero mole percent of residues of the one or more crosslinking monomers, and the at least one shell polymer comprises greater than zero mole percent of residues of the one or more associative monomers. The amount can be any amount greater than zero. For example, the amount can be from about 0.05 to about 100, from about 0.1 to about 100, from about 1 to about 100, from about 0.01 to about 0.1, from about 0.05 to about 0.1, from about 0.1 to about 1 mole percent, or the like. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly incorporated herein.

[0131] In other embodiments, the at least one core polymer comprises about zero mole percent of residues of the one or more crosslinking monomers, and the at least one shell polymer is at least partially crosslinked and comprises greater than about 0.05 mole percent of residues of the one or more crosslinking monomers. The amount can be any amount greater than about 0.05 mole percent. For example, the amount can be from about 0.05 to about 100, from about 0.1 to about 100, from about 1 to about 100, from about 0.01 to about 0.1, from about 0.05 to about 0.1, from about 0.1 to about 1 mole percent, or the like. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly incorporated herein.

[0132] In one embodiment, the at least one core polymer comprises from about 1 to about 95 weight percent of the one or more shell polymers, based on the total weight of the at least one core polymer. In another embodiment, the at least one core polymer comprises from about 5 to about 60 weight percent of the one or more shell polymers, based on the total weight of the at least one core polymer. In other embodiments, the at least one shell polymer comprises greater than about 5 weight percent and less than about 90 weight percent of the total weight of monomeric residues in the core-shell polymer. The value can be from about 5 to about 85, from about 10 to about 80, from about 15 to about 75, from about 20 to about 70, from about 25 to about 65, from about 30 to about 60, from about 35 to about 55, from about 40 to about 50, or from about 45 to about 55 weight percent. In other embodiments, the value is from about 15 to about 40, from about 20 to about 35, or from about 25 to about 30 weight percent. Generally, if the amount is greater than about 90, the shell is too heavy and the desired expansion / swelling is limited. This is undesirable. Similarly, if the weight percent of the shell is too high and the percent of crosslinking in the shell is too high, the expansion / swelling is hindered, which is also undesirable. In various embodiments, the weight percent of the shell is about 75 weight percent and the amount of residues of crosslinking monomers / agents is about 0.1 mole percent. The use of similar shell weight and mole percent of crosslinking monomers ratios are also contemplated herein. If the weight percent is too low, for example less than about 15, 10, or 5 weight percent, the core-shell polymer will not be complete and will tend to form undesirable byproduct (polymer) mixtures. In various non-limiting embodiments, all numerical values (integral and fractional) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly contemplated for use.

[0133] In another embodiment, the at least one core polymer comprises from about 10 to about 40 weight percent or from about 15 to about 35 weight percent of the one or more shell polymers, based on the total weight of the at least one core polymer. In other embodiments, the at least one core polymer is present in an amount greater than about 60 weight percent and up to about 95 weight percent, based on the total weight of the at least one core polymer. In various non-limiting embodiments, all numerical values (integral and fractional) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly contemplated for use.

[0134] In other embodiments, the at least one shell polymer comprises a mole percent of residues of d2) one or more crosslinking monomers that is greater than the mole percent of residues of d1) one or more crosslinking monomers in the at least one core polymer. For example, the mole percent can be greater by 1, 2, 3, 4, 5, 10, 15, 20, 25,... up to about 100 mole percent. In other embodiments, the particle comprises two or more shell polymers, and the at least one shell polymer comprises a mole percent of residues of d2) one or more crosslinking monomers that is less than the mole percent of residues of d1) one or more crosslinking monomers in the at least one core polymer. In further embodiments, the at least one core shell polymer comprises greater than 5 wt% and less than about 90 wt% of the total weight of the particle, for example, about 5 to about 90, about 10 to about 85, about 15 to about 80, about 20 to about 75, about 25 to about 70, about 30 to about 65, about 35 to about 60, about 40 to about 55, or about 50 to about 55 mole percent. In various non-limiting embodiments, all numerical values (integral and fractional) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly considered and contemplated for use herein.

[0135] In other embodiments, b1) and / or f1) is present in the first monomer mixture in at least about 1 mole percent, based on the total moles of monomers in the first monomer mixture, and a1) anionic ethylenically unsaturated monomer is present in the first monomer mixture in 10 mole percent or less, based on the total moles of monomers in the first monomer mixture; b2) and / or f2) is present in the second monomer mixture in at least about 1 mole percent, based on the total moles of monomers in the second monomer mixture, and a2) anionic ethylenically unsaturated monomer is present in the second monomer mixture in 10 mole percent or less, based on the total moles of monomers in the second monomer mixture. In various non-limiting embodiments, all numerical values (integral and fractional) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly considered and contemplated for use herein.

[0136] In other embodiments, the at least one core polymer is the reaction product of a1) and b1), and the at least one shell polymer is the reaction product of a2), b2), and d2); or the at least one core polymer is the reaction product of a1), b1), and e1), wherein a1) is present in an amount less than about 20 mole percent of the first monomer mixture, and e1) is present in an amount greater than about 5 mole percent of the first monomer mixture, and the at least one shell polymer is the reaction product of a2), b2), d2), and e2), wherein a2) is present in an amount less than about 20 mole percent of the second monomer mixture, and e2) is present in an amount greater than about 5 mole percent of the second monomer mixture. In various non-limiting embodiments, all numerical values (integral and fractional) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly considered and contemplated for use herein.

[0137] Consider that any of a2), b2), c2), d2), e2), and f2) may exist independently with any quantity or range of quantity described above with respect to a1), b1), c1), d1), e1), and f1), even if one or more of a1), b1), c1), d1), e1), and f1) are not used, or even if the quantity of one or more of a1), b1), c1), d1), e1), and f1) is different from the quantity of one or more of a2), b2), c2), d2), e2), and / or f2).

[0138] First and second shell polymers

[0139] In other embodiments, the particle (e.g., a core-shell polymer) comprises a first shell polymer (12) and a second shell polymer (14), wherein the first shell polymer (12) is disposed in direct contact with the at least one core polymer (10), and the second shell polymer (14) is disposed in direct contact with the first shell polymer (12). Examples Figures 1-6 As shown.

[0140] In one implementation scheme (e.g., as shown in the example) Figure 1 As shown), the at least one core polymer (10), the first shell polymer (12) and the second shell polymer (14) each have a crosslinking density, the crosslinking density of the first shell polymer (12) is greater than the crosslinking density of the at least one core polymer (10), and the crosslinking density of the second shell polymer (14) is greater than the crosslinking density of the first shell polymer (12) and greater than the crosslinking density of the at least one core polymer (10).

[0141] In another implementation (e.g., as Figure 2 As shown), the at least one core polymer (10), the first shell polymer (12) and the second shell polymer (14) each have a crosslinking density. The crosslinking density of the first shell polymer (12) is greater than that of the at least one core polymer (10), and the crosslinking density of the second shell polymer (14) is less than that of the first shell polymer (12) but greater than that of the at least one core polymer (10).

[0142] In another implementation (e.g., as Figure 3 As shown), the at least one core polymer (10), the first shell polymer (12) and the second shell polymer (14) each have a crosslinking density. The crosslinking density of the first shell polymer (12) is less than that of the at least one core polymer (10), and the crosslinking density of the second shell polymer (14) is greater than that of the at least one core polymer (10) and greater than that of the first shell polymer (12).

[0143] In another embodiment (e.g., as shown in Figure 4 In another embodiment (e.g., as shown in

[0144] In another embodiment (e.g., as shown in Figure 5 In another embodiment (e.g., as shown in

[0145] In another embodiment (e.g., as shown in Figure 6 In another embodiment (e.g., as shown in

[0146] It is also contemplated, for example, in any one or more of Figures 1-6 The term "outermost layer" describes embodiments in which the layer is disposed to form the outer layer of the particle, is exposed to the environment, and has no other layer disposed on its exterior. The term "inner layer" describes a layer that has another layer disposed on at least one surface / side thereof. An inner layer is not exposed to the environment and is not an outer layer.

[0147] Alternatively, one or more intervening polymers can be disposed between the at least one shell polymer and the at least one core polymer. Such intervening polymers can be any type known in the art and any type described herein.

[0148] Additives

[0149] The composition can or can not contain one or more additives, such as any of the additives described herein.

[0150] For example, the pH of the composition can be adjusted using any combination of acidic and / or basic pH adjusting agents known in the art. In various embodiments, the basic material introduced into the composition to neutralize the core-shell polymer can be referred to as a neutralizing agent or pH adjusting agent. Different types of neutralizing agents can be used, including inorganic bases, organic bases, and combinations thereof. Examples of inorganic bases include, but are not limited to, alkali metal hydroxides (particularly sodium, potassium, and ammonium hydroxides) and alkali metal salts of inorganic acids, such as sodium borate (borax), sodium phosphate, sodium pyrophosphate, and the like; and mixtures thereof. Examples of organic bases include, but are not limited to, triethanolamine (TEA), diisopropanolamine, triisopropanolamine, aminomethyl propanol, dodecylamine, cocamine, oleylamine, morpholine, triamylamine, triethylamine, tetrakis(hydroxypropyl)ethylenediamine, L-arginine, aminomethyl propanol, 2-amino-2-hydroxymethyl-l,3-propanediol, and PEG-15 cocamine. Alternatively, other basic materials can be used alone or in combination with the inorganic and organic bases described above. Such materials include surfactants, mixtures of surfactants, pre-neutralized surfactants, or materials that are capable of neutralizing or partially neutralizing carboxyl groups on the polymer backbone when combined with a composition comprising the polymer. Any material that is capable of increasing the pH of the composition is suitable.

[0151] Various acidic materials can be used as pH adjusting agents. Such acidic materials include: organic acids, such as acetic acid, citric acid, tartaric acid, alpha-hydroxy acids, beta-hydroxy acids, salicylic acid, lactic acid, glycolic acid, and natural fruit acids; or inorganic acids, such as hydrochloric acid, nitric acid, sulfuric acid, sulfamic acid, phosphoric acid; and combinations thereof. The acidic pH adjusting agent can be added to the composition after the basic pH adjusting agent is added to the composition. As with the basic pH adjusting agent, other acidic materials can be used alone or in combination with the inorganic and organic acids described above.

[0152] A buffering agent can also be used. Suitable buffering agents include, but are not limited to, carbonates, phosphates, bicarbonates, citrates, borates, acetates, anhydrides, succinates, and the like of alkali or alkaline earth metals, such as sodium phosphate, sodium citrate, sodium acetate, sodium bicarbonate, and sodium carbonate. The pH adjusting agent and / or buffering agent can be used in any amount necessary to achieve and / or maintain the desired pH in the composition.

[0153] The compositions can include or exclude other ingredients in addition to the components described above, such as fluidizing agents, anti-settling agents, plasticizers, surfactants, defoamers, rheology modifiers, leveling agents, gloss modifiers, preservatives, pH adjusters (such as organic amines), biocides, and the like, and combinations thereof. Conventional additives can include, but are not limited to, dispersants, antioxidants, ultraviolet light stabilizers and absorbers, surfactants, wetting agents, leveling agents, defoamers, anti-cratering agents, or combinations thereof. In various embodiments, one or more organic liquids useful as film-forming resins can be used. Examples of such resins include polyamides and cellulose ethers such as ethyl cellulose and ethyl hydroxyethyl cellulose, nitrocellulose and cellulose acetate butyrate resins, and mixtures thereof. Examples of paint resins include short oil alkyd / melamine formaldehyde resins, polyester / melamine formaldehyde resins, thermosetting acrylic / melamine formaldehyde resins, long oil alkyd resins, polyether polyols, and multi-media resins such as acrylics and urea / aldehyde.

[0154] The core-shell polymers of the present disclosure can provide the desired rheological properties to compositions having a pH of from about 2 to about 12, about 3 to about 10, about 4 to about 9, about 5 to about 8, or about 6 to about 7. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values falling within the ranges recited above, are expressly contemplated for use herein.

[0155] The core-shell polymers can be used in aqueous compositions comprising one or more surfactants (such as anionic, cationic, amphoteric, nonionic, and / or combinations of any two or more thereof). In some embodiments, the core-shell polymers are useful thickeners in products comprising active acid components, and are useful thickeners and emulsifiers in emulsions. The core-shell polymers can be used as film formers, spreading aids, and deposition aids for products comprising surfactants, colorants, silicones, and the like.

[0156] As used herein, a polymer can be described as comprising a particular weight or mole percent of a monomer, crosslinker, and the like. It should be understood that the term describes that the polymer comprises a residue of such a compound, as the compound is no longer present after polymerization.

[0157] The compositions can also include or exclude nonionic synthetic associative thickeners (NSATs). Nonionic synthetic associative thickeners can be used to provide viscosity and rheology control. The thickeners are generally nonionic, meaning that they do not carry any net charge in solution. These thickeners generally increase viscosity by forming associations or interactions with other molecules, such as water or polymer chains.

[0158] Hydrophobically modified ethoxylated urethane (HEUR) thickeners generally comprise a polyethylene oxide (PEO) backbone with hydrophobic groups (e.g., alkyl chains) attached via urethane linkages. These hydrophobic groups interact with each other and with the hydrophobic domains of other molecules, resulting in thickening. In various embodiments, the composition includes less than about 2, 1.5, 1, 0.5, or 0.1 active weight percent of hydrophobically modified ethoxylated urethane (HEUR) based on the total weight of the composition. Alternatively, the composition can be free of such polyurethanes.

[0159] Hydrophobically modified cellulose (HMHEC) thickeners are cellulose derivatives modified with hydrophobic groups (e.g., alkyl or alkylaryl moieties) attached to the cellulose backbone. These hydrophobic groups promote the association of the cellulose chains, resulting in increased viscosity.

[0160] Hydrophobically modified polyacrylic acid (HMPAA) thickeners are based on polyacrylic acid (PAA) or a derivative thereof modified with hydrophobic groups. These hydrophobic modifications enable the polymer chains to associate with each other and with other molecules in the system, resulting in thickening.

[0161] Hydrophobically modified polyurethane (HMPU) thickeners are polyurethane-based polymers modified with hydrophobic groups. Like other associative thickeners, these hydrophobic groups promote the association of the polymer chains, resulting in increased viscosity.

[0162] In some embodiments, the inclusion of one or more nonionic synthetic associative thickener (NSAT) can increase the KU to an unacceptable level without correspondingly increasing the ICI to a desired level. However, in other embodiments, the inclusion of one or more nonionic synthetic associative thickener (NSAT) is preferred. In various embodiments, the nonionic synthetic associative thickener is present in an amount of about 0.01 to about 5, about 0.05 to about 2, or about 0.1 to about 1 weight percent based on the total weight of the composition. In other embodiments, the amount is about 0.01 to about 0.09, about 0.02 to about 0.08, about 0.03 to about 0.07, about 0.04 to about 0.06, about 0.04 to about 0.05, about 0.1 to about 0.9, about 0.2 to about 0.8, about 0.3 to about 0.7, about 0.4 to about 0.6, about 0.4 to about 0.5, about 1 to about 5, about 2 to about 4, or about 2 to about 3 weight percent based on the total weight of the composition. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the values noted above and values between the values noted above, are expressly considered to be used herein.

[0163] Alkali swellable

[0164] In various embodiments, the particles are further defined as base-swellable particles. The term “base-swellable” refers to particles that, in these embodiments, can swell upon exposure to basic conditions (e.g., in water, in a composition, etc.). In various embodiments, the swelling of a composition can be measured by laser diffraction, e.g., using a particle size analyzer such as a Malvern Mastersizer. Any method can be used, e.g., ASTM E3340-22, ASTM D1921-18, International Standard ISO 13320-1, etc. Further, the diameter can be reported as x 10 (D v 10), x 50 (D v 50), x 90 (D v 90), and D[4,3] (volume moment average), etc. In other words, any one or more of D v 10 and / or D n 10, D v 50 and / or D n 50, D v 90 and / or D n 90 can be used to report and evaluate particle size. Further, any instrument type, software version, light scattering model applied, complex refractive index real and imaginary parts if Malvern theory is applied, etc. as specified in such methods can be used.

[0165] In various embodiments, particle size can be calculated using a Malvern Zetasizer Nano S as follows. For example, three measurements are performed consecutively, with the number of runs per measurement determined automatically by the instrument. The measurement position and attenuation are set automatically by the instrument. The measurement sequence is performed after a 120 second equilibration time at 25 °C. The pre-set values for the dispersant parameters employ the viscosity (0.8872 centipoise) and refractive index (1.330) of water. The refractive index and absorbance of the sample are set to 1.590 and 0.010, respectively. After completion of the sample measurement sequence, the cumulative and distribution analysis is performed by the instrument software (Malvern Zetasizer Software, Version 7.10). The z-average value (in nm) reported is used as a measure of particle size. In some cases, the particle size distribution can render the cumulative analysis unsuccessful (as indicated by the instrument software quality report), so that the z-average value, while reported, can not be reliably calculated. In such cases of cumulative analysis / z-average unreliable, the particle size of the peak with the highest volume fraction in the volume particle size distribution reported by the instrument software can be used as the particle size if the distribution analysis passes the quality checks indicated by the instrument software.

[0166] In various embodiments, the particle has a first diameter measured at a pH of about 3 to about 5, and a second diameter measured at a pH of about 8, wherein the second diameter is greater than the first diameter. For example, the second diameter can be about 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%... up to about 100% or more greater than the first diameter. Also, the diameters can be measured using any of the methods described above or known in the art, and reported, so long as the first and second diameters are measured using the same method for accurate comparison. In various non-limiting embodiments, all numerical values (integers and fractions) and numerical ranges, including the numerical values and ranges recited above, are expressly incorporated herein by reference.

[0167] Viscosity modification of the composition

[0168] Without wishing to be limited by theory, it is believed that the core-shell polymer swells upon neutralization in the composition, thereby increasing the viscosity of the composition. Swelling of the core-shell polymer is also believed to affect the low, medium (KU viscosity), and high (ICI viscosity) shear viscosity curves.

[0169] In various embodiments, the composition exhibits an ICI viscosity of greater than about 0.8 poise and a KU viscosity of less than about 140 gram Krebs units. In other embodiments, the composition exhibits an ICI viscosity of greater than about 0.6 poise and a KU viscosity of less than about 140 gram Krebs units. In various embodiments, the ICI viscosity is about 0.6 to about 2, about 0.7 to about 2, about 0.8 to about 2, about 0.9 to about 1.9, about 1 to about 1.8, about 1.2 to about 1.7, about 1.3 to about 1.6, about 1.4 to about 1.5 poise. In other embodiments, the ICI viscosity is greater than about 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9 poise. In other embodiments, the ICI viscosity is about 1.2 to about 1.7, about 1.2 to about 1.6, about 1.2 to about 1.5, about 1.5 to about 2, about 1.6 to about 1.9, about 1.6 to about 1.8, about 1.5 to about 1.8, etc. poise, typically measured at about 25 °C. ICI viscosity can be determined using methods according to ASTM D4287, ISO 2884, and BS 2900. More specifically, ICI viscosity is typically obtained using a Brookfield CAP 2000+ ICI Cone and Plate Viscometer (High Torque Model), which is provided by AMETEK Brookfield, with U.S. headquarters in Middleboro, MA. This model conforms to ASTM D4287, ISO 2884, and BS 2900 standards. Samples are typically analyzed for ICI viscosity at 25 °C, 900 RPM using a #1 spindle. The sample temperature is first allowed to equilibrate between the cone and plate for 60 seconds, then the measurement is taken over 30 seconds.

[0170] Viscosity values are obtained using a cone and plate type viscometer and provide information on the flow characteristics of a material under high shear conditions (similar to conditions encountered during application: brushing, spraying, electrostatic disk or roller coating). In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the values noted above and values between the values noted above, are expressly considered to be used herein.

[0171] In addition, the composition can exhibit a KU viscosity of less than about 140, 135, 130, 125, 120, 115, 110, 105, 100, 95, or 90 Krebs units. In various embodiments, the KU viscosity is about 90 to about 140, about 95 to about 135, about 100 to about 130, about 105 to about 125, about 110 to about 120, about 115 to about 120, about 100 to about 110, about 100 to about 105, or about 105 to about 110 Krebs units, typically measured at about 23 °C. KU viscosity is determined according to ASTM D562. KU viscosity is typically reported in Krebs units (KU), which tends to be unique to Stormer viscometers and the like. Vibration viscometers, such as resonance or vibration viscometers, can also be used. Most typically, about 300 grams of the composition is added to a 12-ounce wide-mouth plastic bottle, and then the KU viscosity is analyzed using a Stormer viscometer, model DS Byko-visc, manufactured by BYK-Gardner Gmbh, headquartered in Geretsried, Germany, which conforms to ASTM D 562 standards, run at 200 rpm at about 23 °C, using a paddle rotor 8340. In various non-limiting embodiments, all numerical values (integers and decimals) and numerical ranges, including the above-mentioned numerical values and numerical values therebetween, are expressly considered for use herein.

[0172] The relative importance of ICI and KU viscosity depends on the formulation, typically divided into DIY (do-it-yourself) and contractor formulations. Pigment volume concentration (or PVC) is used to describe the volume (not weight) of pigment in a paint film. PVC indicates how much of the volume of the paint film is made up of pigment versus the amount made up of binder. The critical pigment volume concentration (CPVC) is the pigment concentration at which pigment packs as closely as possible and the binder just fills the space between the pigments. In many DIY premium paints, the PVC is typically below CPVC. In contractor formulations, the PVC is typically above CPVC.

[0173] In most premium DIY paint formulations, the desired KU viscosity is about 95 to about 105, and the ICI viscosity is about 1.2 to about 1.5. In contractor formulations, the KU viscosity is typically about 95 to about 120, and the ICI viscosity is typically about 0.6 or higher. In certain regions, contractors will thin the formulation, so a lower KU viscosity drop can be useful. Unexpectedly, the polymers of the present disclosure exhibit a lower KU viscosity drop upon thinning, as exemplified in at least embodiments HH and II described below, as compared to control formulations.

[0174] Preparation of the core shell polymer

[0175] The core-shell polymers can be formed using any method in the art. More specifically, the core-shell polymers include at least two polymers (i.e., the at least one core polymer and the at least one shell polymer) which can be synthesized using any method known in the art. For example, the polymerization can be carried out sequentially by free radical emulsion polymerization techniques known in the art.

[0176] Synthesis of the core polymer

[0177] In various embodiments, the at least one core polymer is synthesized from a first monomer mixture including one or more of a1) - f1) above in a first emulsion polymerization step. Chain transfer agents can also be used, as described in more detail below.

[0178] In another embodiment, a first monomer pre-emulsion can be used, wherein the first monomer mixture can be emulsified in a first vessel with water and a surfactant mixture prior to being added to the reactor where emulsion polymerization takes place. In another embodiment, the first monomer mixture is added to the reactor where emulsion polymerization takes place without the addition of water or surfactant.

[0179] The monomers a1) - f1) can be polymerized in the presence of a suitable free radical forming initiator, for example, to provide an emulsion of the at least one core polymer. In one embodiment, the polymerization is typically initiated in a "seed" process, in which seed polymer particles are formed as loci for subsequent polymerization.

[0180] In free radical emulsion polymerization, a free radical initiator is used which generates free radicals during polymerization. As used herein, the initiating system can be any free radical initiating system. The free radical initiator is typically present in an amount of about 0.01 wt% to about 3 wt% based on the total weight of monomers. In one embodiment, the initiating system has a solubility in water at 25 °C of at least 0.1 weight percent. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the numerical values and ranges of values stated above, are expressly incorporated herein.

[0181] Suitable initiators include, but are not limited to, peroxides, azo initiators, and redox systems, such as hydrogen peroxide and erythorbic acid, and metal ion based initiation systems. Initiators can also include inorganic and organic peroxides, such as hydrogen peroxide, benzoyl peroxide, acetyl peroxide, and lauryl peroxide; organic hydroperoxides, such as cumene hydroperoxide and t-butyl hydroperoxide. In one embodiment, inorganic peroxides are typical, such as sodium, potassium, and ammonium persulfate. In another embodiment, the initiator includes metal ion based initiation systems, including iron and hydrogen peroxide, and combinations of iron with other peroxides. Organic peracids such as peracetic acid can be used. The peroxides and peracids can optionally be activated with a reducing agent, such as sodium bisulfite, sodium formaldehyde, or ascorbic acid, transition metals, hydrazine, and the like. Azo initiators, especially water soluble azo initiators, can also be used. Water soluble azo initiators include, but are not limited to: 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] hydrogen sulfate dihydrate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate, 2,2'-azobis{2-[l-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(l-imino-l-pyrrolidinyl-2-ethylpropane) dihydrochloride, 2,2'-azobis{2-methyl-N-[l,l-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and the like.

[0182] Optionally, other emulsion polymerization additives and processing aids well known in the art of emulsion polymerization, such as co-emulsifiers, solvents, buffers, chelating agents, inorganic electrolytes, polymeric stabilizers, biocides, antifoams, and pH adjusters, can be included in the polymerization system. The primary emulsifier is typically an anionic surfactant, such as sodium dodecyl sulfate. These are well known in the art.

[0183] In one embodiment, a surfactant selected from ethoxylated C 10 to C 22An auxiliary emulsification aid of a fatty alcohol (or mixture thereof) is added to the reactor. In one embodiment, the fatty alcohol comprises an ethoxylated degree of about 5 to about 250 moles, in another embodiment about 8 to 100 moles, and in a further embodiment about 10 to 50 moles. Exemplary ethoxylated fatty alcohols include lauryl alcohol ethoxylate, myristyl alcohol ethoxylate, cetyl alcohol ethoxylate, stearyl alcohol ethoxylate, cetearyl alcohol ethoxylate, sterol ethoxylate, oleyl alcohol ethoxylate, and behenyl alcohol ethoxylate. In another embodiment, suitable ethoxylated fatty alcohols include Ceteth-20, Ceteareth-20, and Steareth-20, Behenth-25, and mixtures thereof. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the numerical values recited above and values between the recited values, are expressly incorporated herein.

[0184] If used, the amount of ethoxylated fatty alcohol, based on the total weight of the emulsion, can be in one embodiment from about 0.01% to 10% by weight, in another embodiment from about 0.1% to about 5% by weight, and in a further embodiment from about 0.3% to about 3% by weight. In various non-limiting embodiments, all numerical values (both integers and fractions) and ranges of values, including the numerical values recited above and values between the recited values, are expressly incorporated herein.

[0185] Two stage polymerization

[0186] A typical two-stage polymerization, which can or can not be used, is described below. First, a first monomer mixture comprising one or more of a1) - f1) above and optional chain transfer agent is mixed in a first vessel and combined with an aqueous solution of emulsification surfactant (e.g., anionic surfactant) to make a monomer pre-emulsion. Optional processing aids (e.g., auxiliary emulsifiers) can be added as desired.

[0187] The monomers can be introduced into the aqueous feed to the reactor as a monomer pre-emulsion or as separate monomer mixtures and aqueous surfactant solution, the feed optionally including surfactant. When a first monomer mixture is used, the aqueous surfactant solution can be added to the reactor at the same time as or immediately after the first monomer mixture is added. The contents of the reactor can be stirred and a small amount of free radical initiator can be added to the reactor to initiate the formation of seed particles, which is referred to as the seed stage. After the seed stage is complete, the first monomer mixture can be added to the reactor as a monomer mixture or as a monomer pre-emulsion simultaneously with the initiator feed, or as the first monomer mixture simultaneously with the aqueous surfactant solution feed and the initiator feed. Alternatively, the initiator can be added prior to the monomer mixture being added to the reactor. Typically, the total polymer solids content of the core polymer or polymer emulsion is from about 10 to about 45 weight percent. While the at least one core polymer is synthesized in the emulsion, it is recognized that the at least one core polymer can be provided in dry powder form if desired. This is particularly useful for binders that are redispersible powders.

[0188] Next, the at least one shell polymer is formed in a second polymerization step. The second monomer mixture of a2) - f2) can be added as a monomer mixture or as a monomer pre-emulsion simultaneously with the initiator feed, or as the second monomer mixture simultaneously with the aqueous surfactant solution feed and the initiator feed. Alternatively, the initiator can be added prior to the second monomer mixture being added to the reactor. The final product is a two-stage polymer, including the at least one core polymer completely or partially surrounded by the at least one shell polymer.

[0189] In alternative embodiments, only a portion of the total amount of surfactant desired to be used is initially present in the reactor, with the remainder being added as a co-current stream with the monomer mixture stream and the initiator stream for all steps of the polymerization.

[0190] Optionally, further successive free radical emulsion polymerization stages can be run to obtain a multi-layer polymer morphology, such that successive polymer stages differ at least by the mole percent of crosslinking agent used in that stage. In stages where a linear polymer is desired, a monomer mixture without crosslinking agent can be used. In stages where a crosslinked polymer is desired, the monomer mixture will include a crosslinking agent.

[0191] To obtain the properties desired for any particular end use application, any of the following can be adjusted: (i) the relative mole ratios of the individual monomers, (ii) the mass percent of each of the at least one core and the at least one shell polymer, (iii) the selection of monomers, crosslinking agents or associative monomers in any of the polymers, (iv) the rate of addition of the first and second monomer mixtures, the surfactant solution and the initiator solution, and (v) the mole percent of crosslinking monomers / agents in any of the polymers, etc.

[0192] Although core-shell polymers can be synthesized via a series of emulsion polymerization steps to produce aqueous polymer emulsions, it should be recognized that core-shell polymers can ultimately be provided in dry powder form if desired.

[0193] Emulsion polymerization can be carried out in a staged batch process, a staged semi-batch monomer addition process, or a multi-step continuous process, or polymerization can begin as a batch process and then most of the monomers can be added to the reactor continuously in stages (seed semi-batch process), as described above.

[0194] Typically, emulsion polymerization is carried out at a reaction temperature of about 20 to about 99°C. However, higher or lower temperatures may be used. In various non-limiting embodiments, all numerical values ​​(integers and decimals) and ranges of values, including those described above and those in between, are expressly intended to be used herein.

[0195] Emulsion polymerization can be carried out in aqueous or aqueous alcohol media.

[0196] The surfactant may be added to the first and / or second monomer mixture to form a preemulsion. Alternatively, the surfactant may be added directly to the reactor during emulsion polymerization. Alternatively, both methods may be used. In one embodiment, the emulsion polymerization is carried out in the presence of a surfactant in an amount based on the total weight of the emulsion: about 0.01% to about 10% by weight, about 0.1% to about 5% by weight, or about 0.3% to about 3% by weight. In various non-limiting embodiments, all numerical values ​​(integers and decimals) and ranges, including the values ​​described above and those between the values ​​described above, are expressly intended to be used herein.

[0197] Suitable surfactants include anionic, nonionic, amphoteric, and cationic surfactants and mixtures thereof. Anionic and nonionic surfactants and mixtures thereof are most commonly used.

[0198] Suitable anionic surfactants for promoting emulsion polymerization are well known in the art, including but not limited to: sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium (C6-C16) alkylphenoxybenzene sulfonate, disodium (C6-C16) alkylphenoxybenzene sulfonate, disodium (C6-C16) dialkylphenoxybenzene sulfonate, disodium lauryl ether-3 sulfosuccinate, sodium dioctyl sulfosuccinate, sodium disec-butylnaphthalene sulfonate, disodium dodecyl diphenyl ether sulfonate, disodium n-octadecyl sulfosuccinate, phosphate esters of branched alcohol ethoxylates, etc.

[0199] Nonionic surfactants suitable for promoting emulsion polymerization are well-known in the polymer field, including but not limited to: linear or branched alcohol ethoxylates, C8 to C9 ... 12Alkylphenol alkoxylates (e.g., octylphenol ethoxylate), polyoxyethylene polyoxypropylene block copolymers, and the like. Other useful nonionic surfactants include: polyoxyethylene glycol C8to C 22 Fatty acid esters, mono- and diglycerides, sorbitol esters and ethoxylated sorbitol esters, C8to C 22 Fatty acid glycol esters, ethylene oxide and propylene oxide block copolymers having an HLB value greater than about 12, ethoxylated octylphenol, and combinations thereof. In another embodiment, the straight-chain alcohol alkoxylate includes a polyethylene glycol ether of cetearyl alcohol (a mixture of cetyl and stearyl alcohols) sold under the trade name C-17, A-38 and A-39 by BASF. In yet another embodiment, the polyoxyethylene polyoxypropylene block copolymers include copolymers sold under the trade names F127 and L35 by BASF.

[0200] Other suitable nonionic surfactants include, but are not limited to: ethoxylated straight-chain fatty alcohols such as A 5060 (Cognis); Ethal LA-23 and Ethal LA-50 (Ethox Chemicals); branched alkyl ethoxylates such as X 1005 (Clariant); secondary C 12 to C 14 alcohol ethoxylates such as S15-30 and S15-40 (Dow Chemical); ethoxylated octylphenol-based surfactants such as X-305, X-405, and X-705 (Dow Chemical); CA 407, 887, and 897 (Rhodia); OP 3070 and 4070 (BASF); OP 30 and 40 (Uniquema); ethylene oxide and propylene oxide block copolymers such as L35 and F127 (BASF); and secondary C 11 alcohol ethoxylates such as EPN 407 (Clariant). Many other suppliers can be found in trade literature.

[0201] In addition, suitable surfactants are also described in the Handbook of Industrial Surfactants (Fifth Edition, by Michael and Irene Ash), which is incorporated herein by reference in its entirety.

[0202] The emulsion polymerization can be carried out in the presence of a suitable polymeric stabilizer. Suitable polymeric stabilizers (also known as protective colloids) suitable for use in the emulsion polymerization process of the present disclosure are water-soluble polymers, including, for example, synthetic polymers such as polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, polyvinyl pyrrolidone, polyacrylamide, polymethacrylamide, carboxylate functional addition polymers, polyalkyl vinyl ether, and the like; water-soluble natural polymers such as gelatin, pectin, alginates, casein, starch, and the like; and modified natural polymers such as methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, allyl-modified hydroxyethyl cellulose, and the like. In certain cases, it can be advantageous to use a mixture of synthetic and natural protective colloids, for example, a mixture of polyvinyl alcohol and casein. Other suitable natural polymers are mixed ethers such as methylhydroxyethyl cellulose and carboxymethyl methyl cellulose.

[0203] The polymeric stabilizer can be used in an amount of up to about 10 weight percent, or up to about 7.5 weight percent, or up to about 5 weight percent, or up to about 2.5 weight percent, or up to about 2 weight percent, based on the total weight of the emulsion. In another embodiment, when used, the polymeric stabilizer is present in an amount of from about 0.001 weight percent to about 10 weight percent, or from about 0.01 weight percent to about 7.5 weight percent, or from about 0.1 weight percent to about 5 weight percent, or from about 0.5 weight percent to about 2.5 weight percent, or even from about 1 weight percent to about 2 weight percent, based on the total weight of the emulsion. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values falling within the ranges recited above, are expressly contemplated for use herein.

[0204] In various embodiments, the desired amount of water, additional surfactant, and optional processing aids are added to the polymerization reactor. The polymerization reactor is equipped with a connected inert gas inlet and a feed pump, and the reactor contents are maintained under an inert atmosphere and agitated and heated. The reactor contents are heated to a temperature of from about 55 to 98 °C, and maintained under these conditions for about one hour.

[0205] The seed stage can then be conducted in a manner consistent with the pre-emulsion addition of monomers and surfactant described above. The desired amount of the core stage monomer pre-emulsion is fed to the reactor under the surface and the free radical initiator solution is fed separately and simultaneously with the core stage monomer mixture into the reactor contents for a period of about a half hour to two hours. During this period, the reaction temperature is controlled at about 45 to about 95 °C. After the desired amount of the core monomer mixture has been added to the reactor, the feed can be stopped and, if desired, an additional amount of the free radical initiator can be optionally added to the reactor. The resulting reaction mixture can be maintained at a temperature of about 45 to 95 °C for a sufficient time to complete or substantially complete the polymerization reaction and obtain a first stage core-shell polymer emulsion. In various non-limiting embodiments, all numerical values (integers and decimals) and numerical ranges, including the numerical values described above and numerical values between the numerical values described above, are expressly considered to be used herein.

[0206] The second monomer mixture for forming the at least one shell polymer can be mixed in a separate vessel following the same procedure described above. Alternatively, the crosslinking agent can be added to the first vessel containing the remaining materials for forming the at least one core polymer and mixed to form the second monomer mixture. Additional monomers can be added if desired.

[0207] In other embodiments, the monomers for forming the at least one shell polymer are metered into the reactor at a constant rate and mixed with the emulsion described above for forming the at least one core polymer. Simultaneously with the feed for introducing the monomers for forming the at least one shell polymer, a free radical initiator solution in an amount sufficient to reinitiate polymerization is metered into the reaction mixture so that the monomers polymerize in the presence of the at least one core polymer. The temperature is then typically maintained at about 85 °C for about a half hour to two and a half hours, or until the polymerization is complete. Unreacted monomers can be eliminated by completing a monomer scavenging step (e.g., adding more initiator and / or adjusting and maintaining the temperature for a period of time to maintain the flux of free radicals from the thermal initiator residue) as is well known in the art of emulsion polymerization.

[0208] While a typical two-stage polymer process is generally described above, a multi-stage or multi-layer polymer can be formed by sequential emulsion polymerization of monomer feeds in the presence of polymer particles of a previously formed emulsion polymer.

[0209] Chain transfer agents can be used at any stage of the polymerization process of any one or more monomers described above, or can be omitted. Chain transfer agents can be any chain transfer agent known in the art. Suitable chain transfer agents include, but are not limited to: sulfur and disulfide containing compounds such as C1-C18 alkyl mercaptans, C1-C18 alkyl mercapto alcohols, mercapto carboxylic acids, mercapto carboxylic acid esters, thioesters, C1-C18 alkyl disulfides, aryl disulfides, multifunctional mercaptans (such as trimethylolpropane-tris-(3-mercaptopropionate), pentaerythritol-tetra-(3-mercaptopropionate), pentaerythritol-tetra-(mercaptoacetate), and pentaerythritol-tetra-(mercapto-lactate), dipentaerythritol-hexa-(mercaptoacetate), and the like; phosphites and hypophosphites; halogenated alkyl compounds such as carbon tetrachloride, bromo-trichloromethane, and the like; and catalytic chain transfer agents such as cobalt complexes (e.g., cobalt (II) chelates).

[0210] In one embodiment, the chain transfer agent is selected from the group consisting of n-dodecyl mercaptan, methyl-3-mercaptopropionate, and 3-mercaptopropionic acid, 2-mercaptoethanol, combinations thereof, and the like, octyl mercaptan, t-dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, iso-octyl 3-mercaptopropionate, butyl 3-mercaptopropionate, butyl mercaptoacetate, octyl isomercaptoacetate, and dodecyl mercaptoacetate.

[0211] The chain transfer agent can be used in an amount less than about 0.75, about 0.5, about 0.25, or about 0.1 mol% based on the monomers present (typically excluding the crosslinking agent). In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values recited above and numerical values between the recited numerical values, are expressly considered to be used herein.

[0212] Other embodiments

[0213] In one embodiment, the weight ratio of the at least one shell polymer to the at least one core polymer and the amount of crosslinking agent in each of the at least one shell polymer and the at least one core polymer are selected to provide typical rheological properties for a particular end use application.

[0214] In another embodiment, the at least one core polymer comprises greater than 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% by weight of the core-shell polymer. In another embodiment, the core-shell polymer comprises at least one core polymer comprising zero mol% of crosslinking agent residues.

[0215] In some embodiments, the core-shell polymer comprises at least one core polymer comprising residues of a (meth)acrylic C1-C6 alkyl ester monomer. In some embodiments, the at least one core polymer comprises residues of both at least one acrylic C1-C6 alkyl ester monomer and at least one methacrylic C1-C6 alkyl ester monomer.

[0216] In other embodiments, the binder is selected from the group consisting of acrylate, vinyl acrylate, styrene acrylate, and combinations thereof.

[0217] In other embodiments, the binder is selected from the group consisting of acrylate, vinyl acrylate, styrene acrylate, and combinations thereof.

[0218] In other embodiments, the at least one core polymer comprises an amount of residues of the one or more crosslinking monomers that is less than about 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, or 0.1% mol% or less than the amount of residues of the one or more crosslinking monomers in the shell. In various non-limiting embodiments, all numerical values (both integers and fractions) and numerical ranges, including the numerical values described above and numerical values falling within the ranges described above, are expressly contemplated for use herein.

[0219] In other embodiments, the at least one core polymer is a reaction product of a) and b), and the at least one shell polymer is independently a reaction product of a), b), and d).

[0220] In other embodiments, if a1 or a2 is present in an amount less than about 10 mol%, then e1 or e2, respectively, is present in an amount greater than about 10 mol% and up to any amount described above with respect to e1 and / or e2.

[0221] In various non-limiting embodiments, one or more method steps, process steps, components, etc. can be used herein as described in WO 2019 / 096976 and / or US 8,673,277, each of which is expressly incorporated by reference herein in its entirety (in non-limiting embodiments).

[0222] Examples

[0223] The following examples are intended to illustrate embodiments of the disclosed rheology modifiers and various formulations comprising these rheology modifiers and are not intended to limit the scope of the appended claims. In the following examples, the terms “core” monomer mixture / solution and “shell” monomer mixture / solution refer to the monomer mixtures used to form the “core polymer” and “shell polymer,” respectively, as described throughout the disclosure. Alternatively, these can be referred to as the first and second monomer mixtures, respectively.

[0224] In the examples and the accompanying tables, the following materials and abbreviations were used:

[0225] BA - n-butyl acrylate from Arkema, AL

[0226] EA - Ethyl Acrylate from Sasol-Bayonne, NJ

[0227] MAA - Methacrylic Acid from Evonik-Avondale, LA

[0228] MMA - Methyl Methacrylate from Lucite-Nederland, TX

[0229] BEI - Ethoxylated Behenyl Itaconate of Formula I (B) from AkzoNobel Chemicals, NC

[0230] SLS - Sodium Lauryl Sulfate 30% solution from Royal Coatings and Specialty Polymers, IN

[0231] 2-ME - 2-Mercaptoethanol from Millipore Sigma, MA

[0232] TMPTA - Trimethylolpropane Triacrylate from Millipore Sigma, MA

[0233] EGDMA - Ethylene Glycol Dimethacrylate from Millipore Sigma, MA

[0234] DAP - Diallyl Phthalate from Millipore Sigma, MA

[0235] Kathon LX - Biocide from Lanxess, PA

[0236] IPEL BP 507 - Biocide from Lanxess, PA

[0237] Foamblast 327 - Defoamer from DyStar, North Carolina

[0238] Bermocoll Prime 3500 - Cellulosic Thickener from Nouryon, IL

[0239] Bermocoll Prime 2500 - Cellulosic Thickener from Nouryon, IL

[0240] Bermocoll EHM Extra - Cellulosic Thickener from Nouryon, IL

[0241] Bermocoll EHM 200 - Cellulosic thickener from Nouryon, IL

[0242] Bermocoll Flow - Cellulosic thickener from Nouryon, IL

[0243] Alcosperse 787 - Dispersant from Nouryon, IL

[0244] Viscodis 177 - Dispersant from Arkema, PA

[0245] Ethylan 1008SA - Alcohol alkoxylate surfactant from Nouryon, IL

[0246] Masodol 900 - Non-ionic surfactant from Pilot Chemical, OH

[0247] AMP-95 - Alkanolamine from Fisher Scientific, MA

[0248] Tipure R-902+ - Titanium dioxide from Tipure, DE

[0249] Tiona 596 - Titanium dioxide from Tronox, MS

[0250] Minex 4 - Nepheline syenite from Sibelco, NC

[0251] Omyacarb 5 - Calcium carbonate from Omya, OH

[0252] Kamin 2000C - Calcined kaolin clay from KaMin, GA

[0253] Jyck 95 - Dehydroxylated aluminum silicate from Avidco, Singapore

[0254] BYK 024 - Defoamer from BYK-Gardner Gmbh, Germany

[0255] Texanol - Coalescent from Eastman Chemical, TN

[0256] Optifilm 300 - Coalescent from Eastman Chemical, TN

[0257] Celocor AF - Opaque polymer from Arkema, PA

[0258] Encor 282 - vinyl acrylic binder from Arkema, PA

[0259] Encor 481 - styrene acrylic binder from Arkema, PA

[0260] Encor 657 - acrylic binder from Arkema, PA

[0261] Hubercarb Q200 - calcium carbonate from Huber Materials, GA

[0262] Suzorite 80-SF - mica from Imerys, Paris

[0263] Expancel 920WE 40d24 - dry expanded thermoplastic microspheres from Nouryon, IL

[0264] P - poise

[0265] Nipacide CFX 3 - biocide from Clariant, Switzerland

[0266] Steatite 10 - micronized talc

[0267] Primal AC 261 - acrylic binder from Dow, MI

[0268] Aquaflow NLS-200 - non-ionic synthetic associative thickener from Ashland Specialty Chemical Company, DE

[0269] Aquaflow NHS-300 - non-ionic synthetic associative thickener from Ashland Specialty Chemical Company, DE

[0270] Example A

[0271] Example A demonstrates the synthesis of core / shell particles.

[0272] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solution, 278.1 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0273] A "core" monomer mixture was prepared by adding 75.3 grams of methacrylic acid to a beaker containing 292.4 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 75.2 grams of methyl methacrylate, 87.50 grams of ethyl acrylate, and 0.1352 grams of n-dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring, and the residue in the beaker was rinsed into the graduated cylinder with 10.9 grams of water.

[0274] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 27.4 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 21.8 grams of water was added to the reactor contents in one portion. Stirring was continued for an additional 15 minutes.

[0275] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 75 minutes. Simultaneously, an initiator feed containing 126 milligrams of ammonium persulfate dissolved in 11.48 grams of water was added to the reactor contents over the same 75 minutes.

[0276] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor subaerially from the graduated cylinder over 15 minutes. The "shell" monomer solution was prepared by mixing 15.07 grams of methacrylic acid, 15.04 grams of methyl methacrylate, 17.5 grams of ethyl acrylate, and 0.0991 grams of EGDMA, and then thoroughly mixing the contents.

[0277] An initiator feed containing 25.2 milligrams of ammonium persulfate dissolved in 2.3 grams of water was also added over the same 15 minutes as the shell monomer mixture.

[0278] After the shell monomer mixture addition was complete, 209 milligrams of ammonium persulfate dissolved in 19.0 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C, and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature, and 2.1 grams of a 50% sodium hydroxide mixture with 19.3 grams of water was added to the contents over a half hour. The contents were mixed for 15 minutes. Then, 0.35 grams of Nalco / Exxon EC 9086A with 0.74 grams of water was added to the contents, and after a brief mix the milky emulsion product was removed from the reactor, with a pH of 5.6 and a solids content of 31.3%.

[0279] Example B

[0280] Example B demonstrates the synthesis of core-shell particles with 20 mole percent of a1) and a2) to improve water sensitivity, and the use of e1) and e2) (hydroxypropyl acrylate).

[0281] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 278.1 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0282] A "core" monomer mixture was prepared by adding 43 grams of methacrylic acid to a beaker containing 292.4 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 62.6 grams of methyl methacrylate, 97.6 grams of hydroxypropyl acrylate, and then 62.6 grams of ethyl acrylate to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring, and the residue in the beaker was rinsed into the graduated cylinder with 10.9 grams of water.

[0283] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 28.7 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 21.8 grams of water was added to the reactor contents in one portion. Stirring was continued for another 15 minutes.

[0284] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 75 minutes. Simultaneously, an initiator feed containing 126 milligrams of ammonium persulfate dissolved in 11.48 grams of water was added to the reactor contents over the same 75 minutes.

[0285] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor subaerially from the graduated cylinder over 15 minutes. The "shell" monomer solution was prepared by mixing 8.61 grams of methacrylic acid, 12.52 grams of methyl methacrylate, 12.52 grams of ethyl acrylate, 19.52 grams of hydroxypropyl acrylate, and 0.0991 grams of EGDMA, and then mixing the contents thoroughly.

[0286] An initiator feed containing 20.3 milligrams of ammonium persulfate dissolved in 1.85 grams of water was also added over the same 15 minutes that the shell monomer mixture was added.

[0287] After the shell monomer mixture addition was complete, 209 mg of ammonium persulfate was dissolved in 19.02 g of water and added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and 1.2 g of a mixture of 50% sodium hydroxide and 19.3 g of water was added to the contents over a half hour. After mixing for 15 minutes, a mixture of 0.44 g of Nalco / Exxon EC 9086A and 0.93 g of water was added to the contents and after a brief mix the milky emulsion product was removed from the reactor with a pH of 5.6 and a solids content of 29.6%.

[0288] Example C

[0289] Example C illustrates the synthesis of core / shell particles without a2) in the shell.

[0290] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 222.48 g of water and 4.58 g of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0291] A "core" monomer mixture was prepared by adding 60.24 g of methacrylic acid to a beaker containing 233.92 g of water and 4.58 g of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 60.16 g of methyl methacrylate, then 70 g of ethyl acrylate, and 0.1082 g of dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring and the residue in the beaker was rinsed into the graduated cylinder with 8.72 g of water.

[0292] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the seed stage was carried out as follows: 21.9 g of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.25 g of ammonium persulfate dissolved in 17.44 g of water was added to the reactor contents in one portion. Stirring was continued for an additional 15 minutes.

[0293] Then, the remaining core monomer solution was added slowly to the reactor contents sub-surface over 75 minutes. Simultaneously, an initiator feed containing 100.8 mg of ammonium persulfate dissolved in 9.18 g of water was added to the reactor contents over the same 75 minutes.

[0294] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor from the graduated cylinder under the liquid surface over a 15 minute period. The "shell" monomer solution was prepared by mixing 20.8 grams of hydroxypropyl acrylate, 12.03 grams of methyl methacrylate, 12 grams of ethyl acrylate, and 0.0793 grams of EGDMA, and then thoroughly mixing the contents.

[0295] An initiator feed containing 20.2 milligrams of ammonium persulfate dissolved in 1.84 grams of water was also added over the same 15 minute period as the shell monomer mixture was added.

[0296] After the shell monomer mixture addition was complete, 167 milligrams of ammonium persulfate dissolved in 15.22 grams of water was added to the reactor over a 50 minute period. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and 1.4 grams of a 50% sodium hydroxide mixture with 15.44 grams of water was added to the contents over a half hour period. The contents were mixed for 15 minutes. Then 0.35 grams of Nalco / Exxon EC 9086A with 0.75 grams of water was added to the contents and after a brief mix the milky emulsion product was removed from the reactor with a pH of 5.35 and a solids content of 28.91%.

[0297] Example D

[0298] Example D illustrates the synthesis of a core / shell particle without a1) in the core.

[0299] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 222.48 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0300] A surfactant feed solution was prepared by adding 242.5 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) to a 1 liter graduated cylinder. The surfactant feed was added to the reactor contents over a 90 minute period while the following 9 minute core feed was initiated.

[0301] A "core" mixture was prepared by adding 12 grams of ethyl acrylate, 10.85 grams of methacrylic acid, and 0.1165 grams of dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring.

[0302] After sparging the reactor contents with nitrogen at 85°C for at least one hour, 22.96 grams of the core monomer solution was added to the reactor contents subaerially over 1 minute. After stirring the contents for 15 minutes, an initiator feed comprising 25 milligrams of ammonium persulfate dissolved in 17.44 grams of water was also added to the reactor contents in one portion, after which the reactor contents were stirred for 15 minutes.

[0303] After stirring for 15 minutes, 22.96 grams of the core monomer solution was slowly added to the reactor contents subaerially over 9 minutes. Simultaneously, an initiator feed comprising 12 milligrams of ammonium persulfate dissolved in 1.1 grams of water was added to the reactor contents over the same 9 minute period.

[0304] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor subaerially from a graduated cylinder over 81 minutes. The "shell" monomer solution was prepared by mixing 64.96 grams of methacrylic acid, 75.52 grams of ethyl acrylate, 64.73 grams of methyl methacrylate, and 0.4272 grams of ethylene glycol dimethacrylate, followed by thoroughly mixing the contents.

[0305] An initiator feed comprising 109 milligrams of ammonium persulfate dissolved in 9.91 grams of water was also added over the same 81 minute period in which the shell monomer mixture was added.

[0306] After the shell monomer mixture addition was complete, 167 milligrams of ammonium persulfate dissolved in 15.23 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0307] The next day, a mixture of 1.66 grams of 50% sodium hydroxide solution and 15.44 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. A mixture of 1.76 grams of Nalco / Exxon EC 9086A and 3.52 grams of water was added to the contents and, after a brief mix, the cream-colored emulsion product was removed from the reactor, having a solids content of 29.9%.

[0308] Example E

[0309] Example E demonstrates the synthesis of particles having a gradient crosslinking, with increasing crosslinker concentration from the interior of the particle to the surface.

[0310] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, were added 222.48 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were heated to 85°C with overhead stirring and nitrogen sparging for at least 1 hour.

[0311] A "core" mixture was prepared by adding 20.64 grams of methacrylic acid to a beaker containing 233.92 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 60.1 grams of methyl methacrylate, then 44.1 grams of ethyl acrylate and 0.1082 grams of dodecyl mercaptan, and then 124.98 grams of hydroxypropyl acrylate to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring, and the residue in the beaker was rinsed into the graduated cylinder with 8.72 grams of water.

[0312] A crosslinker mixture was prepared in a separate container by adding 4.7592 grams of ethylene glycol dimethacrylate to 16 grams of ethyl acrylate.

[0313] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 24.8 grams of the monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.25 grams of ammonium persulfate dissolved in 17.44 grams of water was added to the reactor contents in one portion. Stirring was continued for an additional 15 minutes.

[0314] Then, the remaining monomer solution was added slowly to the reactor contents sub-surface over 90 minutes. Simultaneously, the crosslinker mixture was added slowly to the monomer mixture over the same 90 minutes. Simultaneously, an initiator feed containing 121 milligrams of ammonium persulfate dissolved in 11 grams of water was added to the reactor contents over the same 90 minutes.

[0315] After the monomer and crosslinker mixtures were added, 167 milligrams of ammonium persulfate dissolved in 15.22 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0316] The next day, a mixture of 0.29 grams of a 50% sodium hydroxide solution and 26.24 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. A mixture of 0.35 grams of Nalco / Exxon EC9086A and 0.74 grams of water was added to the contents, and after a brief mix the milky emulsion product was removed from the reactor, with a pH of 5.1 and a solids content of 32.1%.

[0317] Example F

[0318] Example F demonstrates the synthesis of core / shell particles comprising c1) and c2).

[0319] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 278.1 grams of water and 5.72 grams of a 30% sodium lauryl sulfate aqueous solution (Stanfax 234) were added. The contents were heated to 85°C under overhead stirring and nitrogen sparge for at least 1 hour.

[0320] A "core" monomer mixture was prepared by adding 97.04 grams of methacrylic acid and 2.38 grams of a 50% CD-559 associative monomer aqueous solution to a beaker containing 292.4 grams of water and 5.72 grams of a 30% sodium lauryl sulfate aqueous solution (Stanfax 234). The contents were transferred to a graduated cylinder under overhead stirring. A monomer solution was prepared by adding 63.17 grams of methyl methacrylate, then 75.57 grams of ethyl acrylate, and 0.1363 grams of dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder under stirring, and the residue in the beaker was rinsed into the graduated cylinder with 10.9 grams of water.

[0321] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 27.36 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 21.8 grams of water was added to the reactor contents in one portion. Stirring was continued for another 15 minutes.

[0322] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 75 minutes. Simultaneously, an initiator feed containing 126 milligrams of ammonium persulfate dissolved in 11.48 grams of water was added to the reactor contents over the same 75 minutes.

[0323] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor subaerially from the graduated cylinder over 15 minutes. The "shell" monomer solution was prepared by mixing 18.45 grams of methacrylic acid, 0.45 grams of a 50% CD-559 associative monomer aqueous solution, 12.01 grams of methyl methacrylate, 14.36 grams of ethyl acrylate, and 0.0949 grams of EGDMA, and then thoroughly mixing the contents.

[0324] An initiator feed containing 25.2 milligrams of ammonium persulfate dissolved in 2.3 grams of water was also added over the same 15 minutes that the shell monomer mixture was added.

[0325] After the shell monomer mixture addition was complete, 209 milligrams of ammonium persulfate dissolved in 19.02 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C, and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0326] The next day, a mixture of 2.97 grams of 50% sodium hydroxide solution and 19.3 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. Then, a mixture of 2 grams of Nalco / Exxon EC 9086 and 3 grams of water was added to the contents. After a brief mix, the off-white emulsion product was removed from the reactor, the pH was 5.2, and the solids content was 28.9%.

[0327] Example G

[0328] Example G illustrates the synthesis of core / shell particles comprising f1) and f2).

[0329] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 247 grams of water and 7.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0330] A "core" mixture was prepared by adding 111.71 grams of methacrylic acid to a beaker containing 275.1 grams of water and 7.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 62.12 grams of methyl methacrylate, 63.54 grams of ethyl acrylate, 2.37 grams of 2-ethylhexyl acrylate, and 0.0888 grams of 2-mercaptoethanol to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring.

[0331] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 26.12 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 17.53 grams of water was added to the reactor contents in one portion. Stirring was continued for an additional 15 minutes.

[0332] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 100 minutes. Simultaneously, an initiator feed containing 101.5 milligrams of ammonium persulfate dissolved in 21.98 grams of water was added to the reactor contents over the same 120 minutes.

[0333] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor from the graduated cylinder under the liquid surface over a 20 minute period. The "shell" monomer solution was prepared by mixing 20.37 grams of methacrylic acid, 11.33 grams of methyl methacrylate, 11.59 grams of ethyl acrylate, 0.0162 grams of 2-mercaptoethanol, and 1.94 grams of trimethylolpropane triacrylate, then mixing the contents thoroughly.

[0334] An initiator feed containing 20.3 milligrams of ammonium persulfate dissolved in 4.396 grams of water was also added over the same 20 minute period as the shell monomer mixture was added.

[0335] After the shell monomer mixture addition was complete, 168 milligrams of ammonium persulfate dissolved in 36.42 grams of water was added to the reactor over a 50 minute period. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was allowed to cool to ambient temperature. After a brief mix, the off-white emulsion product was removed from the reactor, which had a pH of 2.47 and a solids content of 29.96%.

[0336] Example H

[0337] Example H demonstrates the synthesis of core / shell particles with 83 mole percent a2) using f2 (2-ethylhexyl acrylate). It is quite surprising that an emulsion with such a high a2) content was successfully synthesized given the fact that 65 mole percent or more of anionic ethylenically unsaturated monomer content results in coagulation and destabilization of the emulsion when only b1 or b2 is used.

[0338] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions were added 278.1 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0339] A "core" monomer mixture was prepared by adding 76.33 grams of methacrylic acid to a beaker containing 292.4 grams of water and 5.72 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 76.06 grams of methyl methacrylate, 88.74 grams of ethyl acrylate, and 0.1370 grams of n-dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder with stirring, and the residue in the beaker was rinsed into the graduated cylinder with 10.9 grams of water.

[0340] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 21.89 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 21.8 grams of water was added to the reactor contents in one portion. The stirring was continued for an additional 15 minutes.

[0341] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 75 minutes. Simultaneously, an initiator feed containing 126 milligrams of ammonium persulfate dissolved in 11.48 grams of water was added to the reactor contents over the same 75 minutes.

[0342] After the "core" monomer mixture feed was complete, the "shell" monomer mixture was added to the reactor subaerially from a graduated cylinder over 15 minutes. The "shell" monomer solution was prepared by mixing 32.18 grams of methacrylic acid, 13.66 grams of 2-ethylhexyl acrylate, and 0.0926 grams of EGDMA, and then thoroughly mixing the contents.

[0343] An initiator feed containing 25.2 milligrams of ammonium persulfate dissolved in 2.3 grams of water was also added over the same 15 minutes as the shell monomer mixture.

[0344] After the shell monomer mixture addition was complete, 209 milligrams of ammonium persulfate dissolved in 19 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature. A mixture of 2.77 grams of 50% sodium hydroxide and 29.3 grams of water was added to the contents over 30 minutes. A mixture of 2 grams of Nalco / Exxon EC 9086A and 3 grams of water was added to the contents and, after a brief mix, the milky emulsion product was removed from the reactor with a pH of 4.7 and a solids content of 28.6%.

[0345] Example I-M demonstrates the synthesis of polymeric particles having three layers (one core and two shells) with each layer having different levels of crosslinker. These examples also demonstrate such multi-layer particles having different levels of anionic ethylenically unsaturated monomer content, as well as the use of a hydroxyl-containing monomer (non-ionic ethylenically unsaturated monomer), hydroxyethyl acrylate.

[0346] Example I

[0347] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 266.1 grams of water and 5.49 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparging for at least 1 hour.

[0348] A surfactant feed solution was prepared by adding 280.7 grams of water and 5.49 grams of a 30% sodium lauryl sulfate aqueous solution (Stanfax 234) to a 1 liter glass graduated cylinder. The surfactant feed was added completely to the reactor contents over 90 minutes while the operation of Layer 1 was initiated.

[0349] A "Layer 1" mixture was prepared by adding 43.41 grams of methacrylic acid to a beaker. The contents were transferred to a graduated cylinder under overhead stirring. A monomer solution was prepared by adding 93.74 grams of ethyl acrylate and 0.1423 grams of dodecyl mercaptan to a glass beaker. The monomer solution was added to the contents of the graduated cylinder under stirring.

[0350] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the Layer 1 monomer solution was added slowly to the reactor contents subaerially over 45 minutes. Simultaneously, an initiator feed containing 72 milligrams of ammonium persulfate dissolved in 6.54 grams of water was added to the reactor contents over the same 45 minutes.

[0351] After the "Layer 1" monomer mixture feed was complete, a "Layer 2" monomer mixture was added from the graduated cylinder to the reactor subaerially over 23 minutes. The "Layer 2" monomer solution was prepared by mixing 5.16 grams of methacrylic acid, 38.97 grams of ethyl acrylate, 19.48 grams of hydroxypropyl acrylate, 0.0592 grams of dodecyl mercaptan, and 4.9689 grams of trimethylolpropane triacrylate, and then mixing the contents thoroughly.

[0352] An initiator feed containing 37 milligrams of ammonium persulfate dissolved in 3.34 grams of water was also added over the same 23 minutes as the Layer 2 monomer mixture.

[0353] After the "Layer 2" monomer mixture feed was complete, a "Layer 3" monomer mixture was added from the graduated cylinder to the reactor subaerially over 23 minutes. The "Layer 3" monomer solution was prepared by mixing 20.8 grams of methacrylic acid, 44.91 grams of ethyl acrylate, 0.0682 grams of dodecyl mercaptan, and 2.8630 grams of trimethylolpropane triacrylate, and then mixing the contents thoroughly.

[0354] An initiator feed containing 37 milligrams of ammonium persulfate dissolved in 3.34 grams of water was also added over the same 23 minutes as the Layer 3 monomer mixture.

[0355] After the Layer 3 monomer mixture addition was complete, 200 milligrams of ammonium persulfate dissolved in 18.23 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0356] The next day, a mixture of 1.61 grams of 50% sodium hydroxide solution and 18.53 grams of water was added to the reactor contents over a 30 minute period. The contents were mixed for 15 minutes. To the contents was added a mixture of 2.11 grams of Nalco / Exxon EC 9086A and 4.22 grams of water and after a brief mix the milky emulsion product was removed from the reactor, having a pH of 5.5 and a solids content of 29.1%.

[0357] Example J

[0358] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions was added 266.98 grams of water and 5.49 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were heated to 85°C under overhead stirring and nitrogen sparge for at least 1 hour.

[0359] A surfactant feed solution was prepared by adding 280.7 grams of water and 5.49 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) to a 1 liter glass graduated cylinder. The surfactant feed was added completely to the reactor contents over a 90 minute period while the operation of Layer 1 was begun.

[0360] A "Layer 1" monomer mixture was prepared by adding 12.95 grams of ethyl acrylate and 0.0128 grams of dodecyl mercaptan to a glass graduated cylinder.

[0361] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the Layer 1 monomer solution was added slowly to the reactor contents subaerially over a 1 minute period. Simultaneously, an initiator feed containing 1 milligram of ammonium persulfate dissolved in 0.1 grams of water was added to the reactor contents over the same 1 minute period.

[0362] After the Layer 1 monomer mixture feed was complete, the Layer 2 monomer mixture was added to the reactor from the graduated cylinder subaerially over a 71 minute period. The Layer 2 monomer solution was prepared by mixing 66.52 grams of methacrylic acid, 143.63 grams of ethyl acrylate, 0.2180 grams of dodecyl mercaptan, and 6.5409 grams of trimethylolpropane triacrylate in a glass graduated cylinder and then thoroughly mixing the contents.

[0363] An initiator feed containing 103 milligrams of ammonium persulfate dissolved in 7.26 grams of water was also added over the same 71 minute period as the Layer 2 monomer mixture.

[0364] After the "Layer 2" monomer mixture feed was complete, the "Layer 3" monomer mixture was added to the reactor from the graduated cylinder under the liquid surface over a 14 minute period. The "Layer 3" monomer solution was prepared by mixing 12.63 grams of methacrylic acid, 27.28 grams of ethyl acrylate, 0.0414 grams of dodecyl mercaptan, and 3.9752 grams of trimethylolpropane triacrylate, and then thoroughly mixing the contents.

[0365] Also during the same 14 minute period of the Layer 3 monomer mixture addition, an initiator feed was added comprising 20 milligrams of ammonium persulfate dissolved in 1.43 grams of water.

[0366] After the Layer 3 monomer mixture addition was complete, 173 milligrams of ammonium persulfate dissolved in 12.14 grams of water was added to the reactor over a 50 minute period. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was allowed to cool to ambient temperature and stand overnight.

[0367] The next day, a mixture of 1.84 grams of 50% sodium hydroxide solution and 18.53 grams of water was added to the reactor contents over a 30 minute period. The contents were mixed for 15 minutes. A mixture of 2.5 grams of Nalco / Exxon EC 9086A and 5 grams of water was added to the contents and after a brief mix the milky emulsion product was removed from the reactor with a pH of 5.6 and a solids content of 29.4%.

[0368] Example K

[0369] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 266.98 grams of water and 5.49 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. The contents were heated to 85°C with overhead stirring and nitrogen sparge for at least 1 hour.

[0370] A surfactant feed solution was prepared by adding 280.7 grams of water and 5.49 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) to a 1 liter graduated cylinder. The surfactant feed was added to the reactor contents over a 90 minute period while the Layer 1 operation was begun.

[0371] A "Layer 1" mixture was prepared by adding 4.17 grams of methacrylic acid, 9 grams of ethyl acrylate, 0.0137 grams of dodecyl mercaptan, and 0.5482 grams of ethylene glycol dimethacrylate to a graduated cylinder.

[0372] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the first layer monomer solution was added slowly to the reactor contents subaerially over 4.5 minutes. Simultaneously, an initiator feed comprising 300 milligrams of ammonium persulfate dissolved in 20.93 grams of water was added to the reactor contents over the same 4.5 minutes.

[0373] After the first layer monomer mixture feed was complete, the second layer monomer mixture was added subaerially from a graduated cylinder to the reactor over 14.4 minutes. The second layer monomer solution was prepared by mixing 23.13 grams of methacrylic acid, 17.92 grams of ethyl acrylate, 0.0442 grams of dodecyl mercaptan, and 2.8391 grams of ethylene glycol dimethacrylate in a glass graduated cylinder, and then thoroughly mixing the contents.

[0374] An initiator feed comprising 24 milligrams of ammonium persulfate dissolved in 2.23 grams of water was also added over the same 14.4 minutes as the second layer monomer mixture.

[0375] After the second layer monomer mixture feed was complete, the third layer monomer mixture was added subaerially from a graduated cylinder to the reactor over 71.1 minutes. The third layer monomer solution was prepared by mixing 68.45 grams of methacrylic acid, 147.8 grams of ethyl acrylate, 0.2244 grams of dodecyl mercaptan, and 0.4502 grams of ethylene glycol dimethacrylate, and then thoroughly mixing the contents.

[0376] An initiator feed comprising 121 milligrams of ammonium persulfate dissolved in 11 grams of water was also added over the same 71.1 minutes as the third layer monomer mixture.

[0377] After the third layer monomer mixture feed was complete, 200 milligrams of ammonium persulfate dissolved in 18.26 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C, and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0378] The next day, a mixture of 2.23 grams of 50% sodium hydroxide solution diluted with 18.53 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. Then a mixture of 2.5 grams of Nalco / Exxon EC 9086A and 5 grams of water was added to the contents, and after a brief mix the milky emulsion product was removed from the reactor, which had a pH of 5.6 and a solids content of 28.9%.

[0379] Example L

[0380] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 266.98 grams of water and 5.49 grams of 30% sodium lauryl sulfate aqueous solution (Stanfax 234) were added. The contents were heated to 85°C under overhead stirring and nitrogen sparge for at least 1 hour.

[0381] A surfactant feed solution was prepared by adding 280.7 grams of water and 5.49 grams of 30% sodium lauryl sulfate aqueous solution (Stanfax 234) to a 1 liter glass graduated cylinder. The surfactant feed was added completely to the reactor contents over 90 minutes while the operation of Layer 1 was initiated.

[0382] A "Layer 1" monomer mixture was prepared by adding 3.99 grams of methacrylic acid, 8.62 grams of ethyl acrylate, 0.0131 grams of dodecyl mercaptan, and 1.1028 grams of ethylene glycol dimethacrylate to a glass graduated cylinder.

[0383] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the Layer 1 monomer solution was added slowly from the graduated cylinder under the surface to the reactor contents over 1 minute. Simultaneously, an initiator feed containing 300 milligrams of ammonium persulfate dissolved in 20.93 grams of water was added to the reactor contents over the same 1 minute.

[0384] After the Layer 1 monomer mixture feed was complete, a "Layer 2" monomer mixture was added from the graduated cylinder under the surface to the reactor over 67 minutes. The Layer 2 monomer solution was prepared by mixing 65.12 grams of methacrylic acid, 140.6 grams of ethyl acrylate, and 0.2134 grams of dodecyl mercaptan in a glass graduated cylinder, and then mixing the contents thoroughly.

[0385] An initiator feed containing 115 milligrams of ammonium persulfate dissolved in 10.44 grams of water was also added over the same 67 minutes as the Layer 2 monomer mixture.

[0386] After the Layer 2 monomer mixture feed was complete, a "Layer 3" monomer mixture was added from the graduated cylinder under the surface to the reactor over 18 minutes. The Layer 3 monomer solution was prepared by mixing 12.63 grams of methacrylic acid, 27.28 grams of ethyl acrylate, 0.0414 grams of dodecyl mercaptan, and 3.9752 grams of trimethylolpropane triacrylate, and then mixing the contents thoroughly.

[0387] An initiator feed containing 31 milligrams of ammonium persulfate dissolved in 2.78 grams of water was also added over the same 18 minutes as the Layer 3 monomer mixture.

[0388] After the addition of the third layer monomer mixture was complete, 200 mg of ammonium persulfate dissolved in 18.23 g of water was added to the reactor over a 50 minute period. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was allowed to cool to ambient temperature and stand overnight.

[0389] The next day, a mixture of 2.17 g of 50% sodium hydroxide solution diluted with 18.53 g of water was added to the reactor contents over a 30 minute period. The contents were mixed for 15 minutes. Then a mixture of 2.5 g of Nalco / Exxon EC 9086A and 5 g of water was added to the contents and after a brief mix the product was removed from the reactor as a milky emulsion with a pH of 5.5 and a solids content of 29.8%.

[0390] Example M

[0391] Into a 1 liter glass reactor equipped with an inlet for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 266.98 g of water and 5.49 g of 30% sodium lauryl sulfate aqueous solution (Stanfax 234) were added. The contents were heated to 85°C and held for at least 1 hour with overhead stirring and nitrogen sparge.

[0392] A surfactant feed solution was prepared by transferring 280.7 g of water and 5.49 g of 30% sodium lauryl sulfate aqueous solution (Stanfax 234) into a 1 liter glass graduated cylinder. The surfactant feed was added to the reactor contents over a 90 minute period while the first layer was being set up.

[0393] A "first layer" mixture was prepared by adding to a glass graduated cylinder 3.99 g of methacrylic acid, 3.99 g of methacrylic acid, 8.62 g of ethyl acrylate, 0.0131 g of dodecyl mercaptan, and 1.1028 g of ethylene glycol dimethacrylate.

[0394] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the first layer monomer solution was added slowly to the reactor contents from under the liquid surface over a 1 minute period. Simultaneously, an initiator feed containing 300 mg of ammonium persulfate dissolved in 20.93 g of water was added to the reactor contents over the same 1 minute period.

[0395] After the addition of the "first layer" monomer mixture was complete, the "second layer" monomer mixture was added from the graduated cylinder to the reactor from under the liquid surface over a 40 minute period. The "second layer" monomer solution was prepared by mixing 36.92 g of methacrylic acid, 79.72 g of ethyl acrylate, 0.1210 g of dodecyl mercaptan, and 6.7992 g of ethylene glycol dimethacrylate in a glass graduated cylinder and then thoroughly mixing the contents.

[0396] An initiator feed containing 68 mg of ammonium persulfate dissolved in 6.22 g of water was also added over the same 40 minute period as the second layer monomer mixture.

[0397] After the addition of the second layer monomer mixture was complete, the third layer monomer mixture was added to the reactor from below the liquid level over a period of 45 minutes from a graduated cylinder. The third layer monomer solution was prepared by mixing 23.89 g of methacrylic acid, 89.51 g of ethyl acrylate, 23.96 g of hydroxyethyl acrylate, and 0.1359 g of dodecyl mercaptan, and then thoroughly mixing the contents.

[0398] An initiator feed containing 77 mg of ammonium persulfate dissolved in 7 g of water was also added over the same 45 minute period as the third layer monomer mixture.

[0399] After the addition of the third layer monomer mixture was complete, 200 mg of ammonium persulfate dissolved in 18.23 g of water was added to the reactor over a period of 50 minutes. The temperature was then raised to 90°C, and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0400] The next day, a mixture of 1.50 g of 50% sodium hydroxide solution diluted with 18.53 g of water was added to the reactor contents over a period of 30 minutes. The contents were mixed for 15 minutes. A mixture of 2.5 g of Nalco / Exxon EC 9086A and 5 g of water was then added to the contents, and after a brief mixing period, the milky emulsion product was removed from the reactor, which had a pH of 5.5 and a solids content of 29.8%.

[0401] Examples N and O demonstrate the synthesis of core / shell materials using ethoxylated crosslinkers.

[0402] Example N

[0403] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, were added 278.1 g of water and 5.72 g of a 30% aqueous sodium dodecyl sulfate solution (Stanfax 234). With overhead stirring and nitrogen sparge, the contents were heated to 85°C and maintained for at least 1 hour.

[0404] A "core" monomer mixture was prepared by adding 75.3 grams of methacrylic acid to a beaker containing 292.4 grams of water and 5.72 grams of a 30% aqueous sodium dodecyl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 75.2 grams of methyl methacrylate, then 87.5 grams of ethyl acrylate and 0.1352 grams of dodecyl mercaptan to a glass beaker. This monomer solution was added to the contents of the graduated cylinder with stirring and the residue in the beaker was rinsed into the graduated cylinder with 10.9 grams of water.

[0405] After the reactor contents were sparged with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 27.4 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 21.8 grams of water was added to the reactor contents in one portion. Stirring was continued for another 15 minutes.

[0406] Then, the remaining core monomer solution was added slowly to the reactor contents subsea over 75 minutes. Simultaneously, an initiator feed containing 126 milligrams of ammonium persulfate dissolved in 11.48 grams of water was added to the reactor contents over the same 75 minutes.

[0407] After the "core" monomer mixture addition was complete, the "shell" monomer mixture was added to the reactor from the graduated cylinder subsea over 15 minutes. The shell monomer solution was prepared by mixing 15.07 grams of methacrylic acid, 15.04 grams of methyl methacrylate, 17.5 grams of ethyl acrylate and 0.346 grams of Komerate T063, then mixing the contents thoroughly.

[0408] An initiator feed containing 25.2 milligrams of ammonium persulfate dissolved in 2.3 grams of water was also added over the same 15 minutes as the shell monomer mixture.

[0409] After the shell monomer mixture addition was complete, 209 milligrams of ammonium persulfate dissolved in 19.02 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0410] The next day, a mixture of 1.2 grams of a 50% sodium hydroxide solution diluted with 19.3 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. Then a mixture of 0.44 grams of Nalco / Exxon EC9086A and 0.93 grams of water was added to the contents and after a brief mix the milky emulsion product was removed from the reactor with a pH of 5.6 and a solids content of 29%.

[0411] Example O

[0412] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 222.48 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234) were added. With overhead stirring and nitrogen sparge, the contents were heated to 85°C and held for at least 1 hour.

[0413] A "core" monomer mixture was prepared by adding 60.24 grams of methacrylic acid to a beaker containing 233.92 grams of water and 4.58 grams of a 30% aqueous sodium lauryl sulfate solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 60.16 grams of methyl methacrylate, then 70 grams of ethyl acrylate, and 0.1082 grams of dodecyl mercaptan to a glass beaker. This monomer solution was added to the contents of the graduated cylinder with stirring, and the beaker rinsed into the graduated cylinder with 8.72 grams of water.

[0414] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was carried out as follows: 21.9 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.25 grams of ammonium persulfate dissolved in 17.44 grams of water was added to the reactor contents in one portion. Stirring was continued for another 15 minutes.

[0415] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 75 minutes. Simultaneously, an initiator feed containing 100.8 milligrams of ammonium persulfate dissolved in 9.18 grams of water was added to the reactor contents over the same 75 minutes.

[0416] After the "core" monomer mixture addition was complete, a "shell" monomer mixture was added subaerially from the graduated cylinder to the reactor over 15 minutes. The "shell" monomer solution was prepared by mixing 20.8 grams of hydroxypropyl acrylate, 12.03 grams of methyl methacrylate, 12 grams of ethyl acrylate, and 0.2768 grams of Komerate T063, then mixing the contents thoroughly.

[0417] An initiator feed containing 20.2 milligrams of ammonium persulfate dissolved in 1.84 grams of water was also added over the same 15 minutes as the shell monomer mixture was added.

[0418] After the shell monomer mixture addition was complete, 167 milligrams of ammonium persulfate dissolved in 15.22 grams of water was added to the reactor over 50 minutes. The temperature was then raised to 90°C, and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature and allowed to stand overnight.

[0419] The next day, a mixture of 1.4 grams of 50% sodium hydroxide solution diluted with 15.44 grams of water was added to the reactor contents over 30 minutes. The contents were mixed for 15 minutes. Then a mixture of 0.35 grams of Nalco / Exxon EC 9086A and 0.75 grams of water was added to the contents and after a brief mix the milky emulsion product was removed from the reactor with a pH of 5.5 and a solids content of 29.1%.

[0420] Examples P-R demonstrate a paint formulation for testing core / shell particles.

[0421] Example P: Flat paint formulation

[0422] The paint formulation process consists of two steps: grind and letdown. In the grind step, water, biocide, grind defoamer, cellulose thickener, dispersant, surfactant, and amine are added to the reactor. Then titanium dioxide, nepheline syenite, calcined clay and / or calcium carbonate and / or dehydroxylated aluminum silicate are dispersed into the mixture under high speed agitation. In the letdown process, binder, biocide, and coalescent are added one at a time and mixed, then rheology modifier, neutralizer, and additional water are added dropwise to the mixture to make the final paint.

[0423] Milling step

[0424] Into a 2 gallon wide mouth grinding jar, 1008.8 grams of water was added and stirred at the lowest speed using an INDCO HSL-2 mixer equipped with an 18 inch shaft and 3 inch disperser disc. To the jar, 6 grams of AMA-415LX and 12 grams of BYK-22 were added sequentially and mixed for 1 minute after each addition. Then to the jar, 4 grams of Bermocoll Prime 2500 was added and mixed for 5 minutes. After all the Bermocoll Prime 2500 was dispersed, to the jar, 28.8 grams of Alcosperse 787, 8 grams of Ethylan 1008SA and 1.33 grams of AMP-95 were added sequentially and mixed for 1 minute after each addition. At the end of the last mix, the three pigments and filler were added slowly in portions and time was allowed for the added material to disperse into the grind mixture after each addition. To the grind mixture, 700 grams of Tipure R-902+ was added in portions over 15 minutes. After the addition was complete, the grind mixture was mixed for an additional 5 minutes. Then to the grind mixture, 460 grams of Minex 4 was added in portions over 10 minutes. After the Minex 4 was added, the grind mixture was mixed for an additional 5 minutes. Next to the grind mixture, 460 grams of Kamin 2000C was added in portions over 15 minutes. The final grind mixture was mixed for 20 minutes. After 20 minutes, a sample of the grind mixture was collected using a 5 ml syringe and poured into the deep of a Hegman gauge. The paint was applied uniformly with the squeegee edge along the groove. The Hegman gauge was then observed for the presence of a distinct line.

[0425]

[0426] For the letdown stage, 2684.9 grams of the grind composition was added to a gallon wide mouth jar. The grind mixture was then stirred using an IKA R W20 mixer equipped with propeller blades at 400 revolutions per minute. To the grind mixture, 1376 grams of Encor 636 was added slowly and the mixture was mixed for 5 minutes. To the mixture, 8.0 grams of BYK 024 was added and mixed for 2 minutes. Next, 68.0 grams of Texanol was added slowly. The mixture was mixed for an additional 10 minutes. Then using this letdown mixture, an additional 6.8 wt. % total of rheology modifiers, AMP-95 and water were added to make the paint formulation.

[0427]

[0428] Example Q: Semi Gloss formulation

[0429] The grind and letdown materials were produced following the procedure steps described in Example P:

[0430]

[0431] Example R: Semi Gloss formulation

[0432] The grind and letdown material was produced following the procedure steps described in Example P:

[0433]

[0434] Examples S-U demonstrate the use of double core / shell particles in paints. The KU and ICI viscosities for these examples were obtained as described in Example S.

[0435] Example S

[0436] Example S demonstrates good performance (>0.8 ICI, <140 KU) of double core / shell particles in paints.

[0437] The polymer of Example 1 was added dropwise to the paint formulation of Example Q under overhead stirring. During the addition, 50% AMP-95 aqueous solution, additional water, and RM 2020 rheology modifier were added to the paint formulation as specified in the table below.

[0438] Paint formulated with Example 1:

[0439] Ingredients Grams Example Q composition 370.8 Rheology modifier: Example A 4 AMP-95, 50% 0.67 Rheology modifier: RM 2020 2.57 Water, adjust 21.95 KU 101.7 ICI (P) 0.890

[0440] KU viscosity was obtained:

[0441] Approximately 300 grams of prepared paint was placed into a 12-ounce wide mouth plastic bottle and KU viscosity analysis was performed using a Stormer viscometer, model DS Byko-visc, manufactured by BYK-Gardner Gmbh, headquartered in Geretsried, Germany, in accordance with ASTM D562 standards at approximately 23°C using a paddle rotor 8340 at 200 rpm.

[0442] ICI viscosity was obtained:

[0443] ICI viscosity was obtained using a Brookfield CAP 2000+ ICI cone and plate viscometer (high torque model) available from AMETEK Brookfield, headquartered in Middleboro, Massachusetts, USA. The instrument model complies with ASTM D4287, ISO 2884, and BS 2900 standards. The ICI viscosity of the sample was analyzed at 25°C, 900 RPM, using a #1 spindle. The sample temperature was first allowed to equilibrate between the cone and plate for 60 seconds, then the measurement was taken over 30 seconds.

[0444] Example T

[0445] Example T demonstrates good performance (>0.8 ICI, <140 KU) in a paint of a double core / shell particle containing e1) and e2) comprising 20 mole% of a1) and a2).

[0446] Under overhead stirring, the polymer of Example B was added dropwise to the paint formulation of Example R. During the addition, 50% AMP-95 aqueous solution, additional water and RM 2020 rheology modifier were added to the paint formulation as specified in the table below.

[0447] Paint formulated with Example B:

[0448] Ingredients Grams Example R composition 1630.9 Rheology modifier: Example B 43.8 AMP-95, 50% 4.22 Rheology modifier: RM 2020 21.90 Water, adjust 165.7 KU 99.8 ICI (P) 1.317

[0449] Example U

[0450] Example U demonstrates good performance (>0.8 ICI, <140 KU) in a paint of a double core / shell particle containing e2 (hydroxypropyl acrylate) in the shell but no a2).

[0451] Under overhead stirring, the polymer of Example C was added dropwise to the paint formulation of Example P. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0452] Paint formulated with Example C:

[0453] Ingredients Grams Example P composition 419.3 Rheology modifier: Example C 12.85 AMP-95, 50% 1.8 Water, adjust 16.05 KU 101 ICI (P) 1

[0454] Example V

[0455] Example V demonstrates good performance (>0.8 ICI, <140 KU) in a paint of a double core / shell particle containing no a1) in the core and having a 90% shell.

[0456] Under overhead stirring, the polymer of Example D was added dropwise to the paint formulation of Example P. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0457] Paint formulated with Example D:

[0458] Ingredients Grams Example P composition 307.5 Rheology modifier: Example D 7 AMP-95, 50% 1.19 Water, adjust 14.28 KU 102.9 ICI (P) 0.981

[0459] Example W-AA demonstrates the use of a multi-layer core / shell particle in a paint.

[0460] Example W

[0461] Example W demonstrates good performance (>0.8 ICI, <140 KU) of a three-layer core / shell particle with 10 mole% a2) in the 2nd layer and e2) present in the 2nd layer in a paint.

[0462] Under overhead stirring, the polymer of Example I was added dropwise to the paint formulation of Example P. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0463] Paint formulated with Example 9:

[0464] Ingredients Grams Example P composition 233 Rheology modifier: Example I 7.2 AMP-95, 50% 0.62 Water, adjust 9.2 KU 132.6 ICI (P) 0.900

[0465] Surprisingly, the particles were able to impart KU and ICI viscosity to the paint formulation despite the low content of a2) in the 2nd layer (10 mole%).

[0466] Example X

[0467] Example X demonstrates good performance (>0.8 ICI, <140 KU) of a three-layer core / shell particle with no a1) in the 1st layer in a paint.

[0468] Under overhead stirring, the polymer of Example J was added dropwise to the paint formulation of Example P. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0469] Paint formulated with Example J:

[0470] Ingredients Grams Example P composition 233 Rheology modifier: Example J 5.9 AMP-95, 50% 0.89 Water, adjust 10.3 KU 137 ICI (P) 0.896

[0471] KU viscosity was obtained:

[0472] KU viscosity analysis was performed on approximately 300 grams of prepared paint in a 12 oz. wide mouth plastic bottle using a DS Byko-visc Model Stormer viscometer produced by BYK-Gardner Gmbh, headquartered in Geretsried, Germany, in accordance with ASTM D562 standards at approximately 23°C using a paddle rotor 8340 at 200 rpm.

[0473] ICI viscosity was obtained:

[0474] ICI viscosity was obtained using a Brookfield CAP 2000+ ICI Cone and Plate Viscometer (High Torque Model) available from AMETEK Brookfield, headquartered in Middleboro, Massachusetts, USA. This model of instrument meets the standards of ASTM D4287, ISO 2884, and BS 2900. The ICI viscosity of the sample was analyzed at 25 °C, 900 RPM, using a #1 spindle. The sample temperature was first allowed to equilibrate between the cone plates for 60 seconds, then the measurement was taken over 30 seconds.

[0475] Example Y

[0476] Example Y demonstrates good performance (>0.8 ICI, <140 KU) in a paint of a three layer core / shell particle with the entire particle containing a difunctional crosslinker and the second layer containing 60 mole% a2).

[0477] The polymer of Example K was added dropwise to the paint formulation of Example P under overhead stirring. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0478] Paint formulated with Example K:

[0479] Ingredients Grams Example P composition 233 Rheology modifier: Example K 7.6 AMP-95, 50% 1.44 Water, adjust 7.8 KU 114.3 ICI (P) 0.992

[0480] Example Z

[0481] Example Z demonstrates good performance (>0.8 ICI, <140 KU) in a paint of a three layer core / shell particle with the entire particle containing a difunctional crosslinker and the third layer containing 50 mole% a2).

[0482] The polymer of Example L was added dropwise to the paint formulation of Example P under overhead stirring. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0483] Paint formulated with Example L

[0484] Ingredients Grams Example P composition 233 Rheology modifier: Example L 6.23 AMP-95, 50% 1.12 Water, adjust 9.67 KU 120 ICI (P) 1.287

[0485] Example AA

[0486] Example AA demonstrates good performance (>0.8 ICI, <140 KU) of a three layer core / shell particle with the entire particle containing a difunctional crosslinker and the third layer containing e2) (hydroxyethyl acrylate).

[0487] The polymer of Example M was added dropwise to the paint formulation of Example P under overhead stirring. During the addition, 50% AMP-95 aqueous solution and additional water were added to the paint formulation as specified in the table below.

[0488] Paint formulated with Example M:

[0489] Ingredients Grams Example P composition 233 Rheology modifier: Example M 6.2 AMP-95, 50% 0.82 Water, adjust 10 KU 119 ICI (P) 0.890

[0490] Examples BB and CC demonstrate the successful use of core / shell particles in joint compounds.

[0491] Example BB

[0492] Into a KitchenAid 6 quart bowl, add 299.00 grams of Hubercarb Q200, 20.00 grams of Suzorite 80-SF, and 7.50 grams of Attagel 40. Using the dough hook, mix the dry ingredients slowly at speed 1. Mix the powders for 5 minutes, then transfer to another container. In the same KitchenAid bowl, add 153.35 grams of water and 14.0 grams of Avicor 325. Then mix the solution at speed 2. While mixing, slowly add 0.50 grams of Mergal 17411, 0.15 grams of BYK 035, and 1.50 grams of propylene glycol. Slowly add 4.0 grams of Example C to the bowl, then mix for 2-3 minutes. After 5 minutes, slowly add the powder mixture to the KitchenAid bowl containing the liquid mixture, with the mixing speed set to 2. Occasionally pause the mixing and use a rubber spatula to mix the powder stuck to the sides of the bowl into the mixture. After all of the joint compound has been added, increase the speed to 3 and mix the joint compound formulation for an additional 10 minutes. The final formulation has a sheen and a creamy consistency.

[0493] Example CC

[0494] Into a KitchenAid 6 quart bowl were added 156.20 grams Hubercarb Q200, 31.24 grams Suzorite 80-SF, 11.72 grams Attagel 40, and 27.34 grams Expancel 920WET 40D24. Using the dough hook, the dry ingredients were mixed slowly at speed 1. The powders were mixed for 5 minutes and then transferred to another container. In the same 6 quart bowl, 243.28 grams of water and 21.87 grams of Avicor 325 were added. This solution was then mixed at speed 2. While mixing, 0.78 grams of Mergal 17411, 0.23 grams of BYK 035, and 2.34 grams of propylene glycol were slowly added. To the bowl, 5.0 grams of Example C were slowly added and mixed for 2-3 minutes. After 5 minutes, the powder mixture was slowly added to the KitchenAid bowl containing the liquid mixture with the mixing speed set to 2. Occasionally pause the mixing and use a rubber spatula to mix the powder stuck to the sides of the bowl into the mixture. After all the joint filler was added, the speed was increased to 3 and the joint filler formulation was mixed for an additional 10 minutes. The final formulation had a sheen and a creamy consistency.

[0495] Example DD

[0496] Example DD illustrates the use of core / shell particles in asphalt formulations.

[0497] Ingredients wt% Water To 100% Polymer of Example 1 1 active wt% 50% sodium hydroxide 0.2 Asphalt (40 - 90 needle penetration) 58 Redicote E-7000 (available from Nouryon) 4

[0498] To make an anionic slow crack asphalt emulsion, the polymer of Example A was dispersed in water with Redicote E-7000. The pH of the mixture was adjusted to pH 10-12 with 50% sodium hydroxide and then heated to 50°C. This mixture was combined with hot (130°C) 40-90 penetration asphalt at high speed by a lab colloid mill. The resulting final slow crack emulsion was cooled to room temperature.

[0499] Examples EE and FF

[0500] Examples EE and FF demonstrate the swelling properties and swelling capacity of the core / shell particles after neutralization. Example FF is particularly surprising given the lack of a2) in the shell.

[0501] A mixture of 100 grams of 1% active of each rheology-modified emulsion or binder was prepared by diluting the emulsions in separate plastic cups with deionized water.

[0502] With stirring, 50% aminomethyl propanol aqueous solution was added to each emulsion mixture to achieve 90% neutralization of total acid groups in the polymer. The amount of 50% aminomethyl propanol required to neutralize 90% of the acid groups in 1 gram of wet emulsion polymer was determined by the following equation:

[0503] [grams of methacrylic acid used in synthesis / (86.1 * total grams of material in synthesis batch)] * 0.875 * 89.1 * 2

[0504] The mixture was stirred for an additional 15 minutes, and then immediately prepared for particle size analysis.

[0505] A drop of the above emulsion or binder mixture was dropped into a Fisher Scientific Fisherbrand disposable cuvette (catalog number 14955129) and repeatedly diluted with deionized water until the white haze was barely visible or just below visibility. The original (unneutralized) starting emulsion or binder was also diluted in a separate cuvette with deionized water to the same condition.

[0506] The diluted samples were measured for particle size using a Malvern Zetasizer Nano S. Three measurements were taken consecutively, with the number of runs per measurement determined automatically by the instrument. The measurement position and attenuation were set automatically by the instrument. The measurement sequence was performed at 25 °C after a 120 second equilibration time. The dispersant parameters used the pre-set viscosity value (0.8872 centipoise) and refractive index (1.330) for water. The refractive index and absorbance of the sample were set to 1.590 and 0.010, respectively. After the sample measurement sequence was complete, the cumulative and distribution analysis was performed by the instrument software (Malvern Zetasizer Software, version 7.10).

[0507] The reported z-average (in nm) was used as a measure of particle size. In some cases, the particle size distribution was such that the cumulative analysis was unsuccessful (as indicated by the instrument software quality report), so the z-average was reported, but the calculation was unreliable. In such cases where the cumulative analysis / z-average was unreliable, the particle size of the highest volume fraction peak in the volume particle size distribution reported by the instrument software was used as the particle size if the distribution analysis passed the quality checks indicated by the instrument software to determine the amount of swelling of the emulsion or binder particles.

[0508] The amount of swelling that occurred for each sample was reported as the percent difference between the post-neutralization and the initial unneutralized particle size divided by the initial unneutralized particle size.

[0509]

[0510]

[0511] The above data show the swelling of the core / shell particles of the present disclosure. In particular, Example FF surprisingly demonstrates that the particle size increased by 1631% despite the absence of a2) in the shell layer.

[0512] Example GG

[0513] Grind and thinning materials were produced following the procedure described in Example P:

[0514]

[0515] Example HH

[0516] Grind and thinning materials were produced following the procedure described in Example P:

[0517]

[0518] Example II

[0519] Grind and thinning materials were produced following the procedure described in Example P:

[0520]

[0521]

[0522] Example JJ

[0523] Example JJ demonstrates that paints formulated with the present materials have higher hiding power after dilution compared to paints formulated with traditional rheology modifiers. It is very surprising that paints formulated with the present materials uniquely maintain their hiding power even after dilution to at most 35% when dried to a film.

[0524] Paints were prepared following the procedure described in Example GG-II. Paint dilutions were prepared by adding water to the paint and mixing the water / paint mixture. The amount of water added was determined by calculating the amount of water needed to reduce the paint solids content to the desired amount. The amount of water needed per 100 grams of paint formulation was determined by the following equation:

[0525] 100 grams / (1 - desired percent dilution x 100) - 100 grams = grams of water needed per 100 grams of starting paint formulation to obtain the desired percent dilution

[0526] From each paint and paint dilution, a thin film was drawn down on a Leneta Hiding Chart with a 6 mL drawdown bar (3 mL wet film) at 100 rpm. After drying for at least 24 hours, the contrast ratio of each thin film was measured.

[0527]

[0528] Example KK

[0529] Example KK demonstrates the synthesis of associated monomer particles containing 16 wt% shell and 1.4 mole% crosslinker (trimethylolpropane triacrylate).

[0530] Into a 1 liter glass reactor equipped with inlets for stirrer, water cooled condenser, thermocouple, nitrogen sparge, and addition of monomers and initiator solutions, 247 grams of water and 7.58 grams of 30% sodium dodecyl sulfate aqueous solution (Stanfax 234) were added. With overhead stirring and nitrogen sparge, the contents were heated to 85°C and held for at least 1 hour.

[0531] A "core" monomer mixture was prepared by adding 19.5 grams of 50% CD-559 associated monomer and 105.5 grams of methacrylic acid to a beaker containing 275.1 grams of water and 7.58 grams of 30% sodium dodecyl sulfate aqueous solution (Stanfax 234). The contents were transferred to a graduated cylinder with overhead stirring. A monomer solution was prepared by adding 61.6 grams of methyl methacrylate, followed by 63 grams of ethyl acrylate and 0.0874 grams of 2-mercaptoethanol. This monomer solution was added to the contents of the graduated cylinder with stirring, and the residue in the beaker was rinsed into the graduated cylinder with 14.1 grams of water.

[0532] After sparging the reactor contents with nitrogen at 85°C for at least one hour, the seed stage was conducted as follows: 27.32 grams of the core monomer mixture was added to the reactor contents over 2 minutes. After stirring for 15 minutes, a seed stage initiator solution containing 0.31 grams of ammonium persulfate dissolved in 17.53 grams of water was added to the reactor contents in one portion. Stirring was continued for another 15 minutes.

[0533] Then, the remaining core monomer solution was added slowly to the reactor contents subaerially over 100 minutes. Simultaneously, an initiator feed containing 121 milligrams of ammonium persulfate dissolved in 26.17 grams of water was added to the reactor contents over the same 100 minutes.

[0534] After the "core" monomer mixture addition was complete, a "shell" monomer mixture was added subaerially from the graduated cylinder to the reactor over 20 minutes. The "shell" monomer solution was prepared by mixing 3.9 grams of CD-559 associated monomer, 21.1 grams of methacrylic acid, 12.3 grams of methyl methacrylate, 12.6 grams of ethyl acrylate, 0.0175 grams of 2-mercaptoethanol, and 2.1 grams of trimethylolpropane triacrylate, and then mixing the contents thoroughly.

[0535] An initiator feed comprising 24 mg of ammonium persulfate dissolved in 5.23 g of water was also added over the same 20 minutes as the shell monomer mixture.

[0536] After the shell monomer mixture addition was complete, 145 mg of ammonium persulfate dissolved in 31.4 g of water was added to the reactor over 50 minutes. The temperature was then raised to 90 °C and the reactor contents were cooked for 1 hour. The sample was cooled to ambient temperature. After brief mixing, a milky emulsion product was removed from the reactor which had a solids content of 29.77% and a pH of 2.6.

[0537] Example LL

[0538] A ground and let down material was produced following the procedure described in Example 6 to produce a paint with a pigment volume concentration of 70% without the use of a cellulosic thickener:

[0539] Milling composition for contractor paint Ingredients (grams) Water 175 Defoamer: BYK-22 2 Dispersant: Alcosperse 602N 8 Surfactant: Ethylan 1005 4 Amp-95 (50%) 4 Titanium dioxide: Tipure R-706 60 Nepheline syenite: Minex 4 270 Calcined Kaolin: Kamin 2000C 100 Calcium Carbonate: Hubercarb Q200 50

[0540] Contractor paint let down composition of Example LL

[0541] Paint Thinner Composition Component Gram Grinding Composition 673 Binder: Acronal 4670 121 Defoamer: BYK-035 5 Coalescent: Texanol 6 Biocide: Kathon LX 1.5% 1 Water 324

[0542] The polymer of Example KK was added dropwise to the paint formulation under overhead stirring. During the addition, Acrysol RM 2020 and additional water were added to the paint formulation as specified in the table below.

[0543] Paint formulated with Example KK:

[0544] Component Gram Example LL Grinding / Thinner Composition 1130 Rheology Modifier: Example KK 13.19 Acrysol RM 2020 10 Water, Adjusted 1.8 KU 104.8 ICI (P) 0.973

[0545] Example MM

[0546] A ground and let down material was produced following the procedure described in Example 6 to produce a paint with a pigment volume concentration of 70% using the cellulosic Natrosol Plus 330:

[0547]

[0548] Contractor paint let down composition of Example MM

[0549]

[0550] Acrysol RM 2020 was added to the paint formulation as specified in the table below.

[0551] Component Gram Example MM Grinding / Thinner Composition 1145.5 Acrysol RM 2020 10 KU 99.5 ICI (P) 0.665

[0552] The performance of Examples LL and MM demonstrates that, at similar KU levels, the polymers of the present invention unexpectedly exhibit greater ICI development capabilities than cellulose thickeners in contractor paint formulations, and with higher efficiency, as evidenced by achieving these KU and ICI levels at much lower dosages.

[0553] Example Modifier Effective Dose % KU ICI (P) LL Example KK 0.34 104.8 0.973 MM Natrosol Plus 330 0.48 99.9 0.665

[0554] The formulation data for Examples S–AA demonstrate the KU and ICI construction properties of the core / shell particles of this disclosure. Data in Example JJ show that paints formulated with the core / shell particles of this disclosure provide better hiding power after dilution compared to currently available materials, an unexpected benefit of this invention.

[0555] As illustrated in Examples W-AA, the technology of this disclosure allows for the use of multilayer monomer compositions and crosslinking densities. This means that performance in a wide range of shear rates (e.g., Brookfield viscosity, KU viscosity, and ICI viscosity), paint hiding power, spreadability, sag and leveling properties, and stability can be finely controlled. Furthermore, this differs from known prior art, which often requires the outer layer to have the most crosslinking agent, while this disclosure and the examples allow for more or less crosslinking agent.

[0556] Surprisingly, the particles swelled even with an anionic olefinic unsaturated monomer content of 0–10%. This was confirmed in Example FF, where the shell had 0 mol% anionic olefinic unsaturated monomer, which was unexpected because the anionic olefinic unsaturated monomer content is a key driver of polymer chain solubility and swelling. Without being bound by theory, it is believed that the polymer can still swell despite a 0% anionic olefinic unsaturated monomer content in the shell due to the presence of nonionic olefinic unsaturated monomers in the shell layer.

[0557] Surprisingly, it was found that while stable emulsions with minimal coalescence were formed using up to 60 mol% of anionic olefinic unsaturated monomers (as in Example K), viable emulsions could still be obtained if the layer contained more than 10 mol% of long-chain hydrophobic olefinic unsaturated monomers (as in Example H, where the shell contains 83 mol% of anionic olefinic unsaturated monomers). This is surprising because when using b1 or b2 alone, a content of 65 mol% or more of anionic olefinic unsaturated monomers would lead to polymer coalescence and instability in the emulsion.

[0558] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described are only examples, and are not intended to limit the scope, applicability or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment. It should be understood that various changes can be made in the function and arrangement of elements described in the exemplary embodiment without departing from the scope of the appended claims, which are to be interpreted in the broadest reasonable manner so as to include all equivalent structures and functions.

Claims

1. An aqueous coating composition comprising: I. water; II. a binder; III. optionally, a pigment; and IV. particles, the particles comprising: A. at least one core polymer that is a polymerization reaction product of a first monomer mixture comprising: al) optionally, one or more anionic ethylenically unsaturated monomers; bl) optionally, one or more short chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 7 or fewer carbon atoms; cl) optionally, one or more associative monomers; dl) optionally, one or more crosslinking monomers; el) optionally, one or more non-ionic ethylenically unsaturated monomers; and fl) optionally, one or more long chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 8 or more carbon atoms; wherein if al) is not present in the first monomer mixture, then el) is present in the first monomer mixture; wherein, if fl) is not present in the first monomer mixture, al) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the first monomer mixture; wherein, if fl) is present in the first monomer mixture, al) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the first monomer mixture; wherein, at least one of bl) and fl) is present in the first monomer mixture; and B. at least one shell polymer disposed around the at least one core polymer, wherein the at least one shell polymer is at least partially crosslinked and is a polymerization reaction product of a second monomer mixture comprising: a2) optionally, one or more anionic ethylenically unsaturated monomers; b2) optionally, one or more short chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 7 or fewer carbon atoms; c2) optionally, one or more associative monomers; d2) one or more crosslinking monomers; e2) optionally, one or more non-ionic ethylenically unsaturated monomers; and f2) optionally, one or more long chain hydrophobic ethylenically unsaturated monomers having a side chain comprising a hydrophobic group having 8 or more carbon atoms; wherein, if a2) is not present in the second monomer mixture, then e2) is present in the second monomer mixture; wherein, if f2) is not present in the second monomer mixture, a2) is present in an amount of 0 to about 60 mol% based on the total moles of monomers in the second monomer mixture; wherein, if f2) is present in the second monomer mixture, a2) is present in an amount of 0 to about 80 mol% based on the total moles of monomers in the second monomer mixture; wherein, at least one of b2) and f2) is present in the second monomer mixture; and wherein, at least one of the first monomer mixture and the second monomer mixture comprises greater than 0 mol% of al) or a2), respectively.

2. The aqueous coating composition of claim 1 having an ICI viscosity greater than about 0.6 poise and a KU viscosity less than about 140 Krebs Units, wherein the particles are further defined as base-swellable particles.

3. The aqueous coating composition of claim 1 or 2, wherein the particles are further defined as alkali-swellable particles having a first diameter measured at a pH of about 3 to about 5, and a second diameter measured at a pH of about 8, wherein the second diameter is at least about 10% greater than the first diameter.

4. The aqueous coating composition of any of the preceding claims, wherein the at least one shell polymer comprises a greater mol% of residues of the d2) one or more crosslinking monomers than a mol% of residues of the d1) one or more crosslinking monomers in the at least one core polymer.

5. The aqueous coating composition of any of claims 1 to 3, wherein the particles comprise two or more shell polymers, and at least one shell polymer comprises a smaller mol% of residues of the d2) one or more crosslinking monomers than a mol% of residues of the d1) one or more crosslinking monomers in the at least one core polymer.

6. The aqueous coating composition of any of the preceding claims, wherein the at least one core-shell polymer comprises greater than 5 wt% and less than about 90 wt% of the total weight of the particles.

7. The aqueous coating composition of any of the preceding claims, wherein: b1) and / or f1) are present in the first monomer mixture in an amount of at least about 1 mol% based on the total moles of monomers in the first monomer mixture, and the a1) anionic ethylenically unsaturated monomer is present in the first monomer mixture in an amount of 10 mol% or less based on the total moles of monomers in the first monomer mixture; and b2) and / or f2) are present in the second monomer mixture in an amount of at least about 1 mol% based on the total moles of monomers in the second monomer mixture, and the a2) anionic ethylenically unsaturated monomer is present in the second monomer mixture in an amount of 10 mol% or less based on the total moles of monomers in the second monomer mixture.

8. The aqueous coating composition of any of the preceding claims, wherein one or both of the at least one core polymer and the shell polymer comprise an increasing crosslinking density gradient measured in a direction extending outward from a center of the at least one core polymer toward the shell polymer, wherein the crosslinking density of the at least one core polymer is optionally less than the crosslinking density of the shell polymer.

9. The aqueous coating composition of any of the preceding claims, wherein the first monomer mixture is free of the d1) one or more crosslinking monomers.

10. The aqueous coating composition of any of the preceding claims, wherein the particles comprise a first shell polymer and a second shell polymer, wherein the first shell polymer is disposed on and in direct contact with the at least one core polymer, and the second shell polymer is disposed on and in direct contact with the first shell polymer.

11. The aqueous coating composition of claim 10, wherein the at least one core polymer, the first shell polymer, and the second shell polymer each have a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer; and the crosslinking density of the second shell polymer is greater than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer.

12. The aqueous coating composition of claim 10, wherein each of the at least one core polymer, the first shell polymer, and the second shell polymer has a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer; and the crosslinking density of the second shell polymer is less than the crosslinking density of the first shell polymer and greater than the crosslinking density of the at least one core polymer.

13. The aqueous coating composition of claim 10, wherein each of the at least one core polymer, the first shell polymer, and the second shell polymer has a crosslinking density, the crosslinking density of the first shell polymer is less than the crosslinking density of the at least one core polymer; and the crosslinking density of the second shell polymer is greater than the crosslinking density of the at least one core polymer and greater than the crosslinking density of the first shell polymer.

14. The aqueous coating composition of claim 10, wherein each of the at least one core polymer, the first shell polymer, and the second shell polymer has a crosslinking density, the crosslinking density of the first shell polymer is greater than the crosslinking density of the at least one core polymer; and the crosslinking density of the second shell polymer is less than the crosslinking density of the at least one core polymer and less than the crosslinking density of the first shell polymer.

15. The aqueous coating composition of claim 10, wherein each of the at least one core polymer, the first shell polymer, and the second shell polymer has a crosslinking density, the crosslinking density of the first shell polymer is less than the crosslinking density of the at least one core polymer; and the crosslinking density of the second shell polymer is less than the crosslinking density of the at least one core polymer and greater than the crosslinking density of the first shell polymer.

16. The aqueous coating composition of claim 10, wherein each of the at least one core polymer, the first shell polymer, and the second shell polymer has a crosslinking density, the crosslinking density of the first shell polymer is less than the crosslinking density of the core polymer; and the crosslinking density of the second shell polymer is less than the crosslinking density of the at least one core polymer and less than the crosslinking density of the first shell polymer.

17. The aqueous coating composition of any of the preceding claims, wherein the one or more c1) and c2) associative monomers are not present in the first and second monomer mixtures.

18. The aqueous coating composition of any of the preceding claims, further comprising a non-ionic synthetic associative thickener (NSAT).

19. The aqueous coating composition of any of the preceding claims, wherein: b1 ) and b2) are independently selected from the group consisting of C1-C7 alkyl esters of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; C1-C7 alkyl amides of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; benzyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate ethoxylate, phenyl (meth)acrylate ethoxylate, 6-hydroxyhexyl (meth)acrylate, and styrene, a-methylstyrene, vinyltoluene, and p-chlorostyrene; vinyl acetate, vinyl butyrate, vinyl hexanoate, vinyl valerate, vinyl hexanoate, vinyl caprolactam, (meth)acrylonitrile, isobutylene, diisobutylene, isoprene, vinyl chloride, vinylidene chloride, and combinations thereof; and f1) and f2) are independently selected from the group consisting of C8-C 32 alkyl esters of acrylic acid, maleic acid, itaconic acid, and methacrylic acid; C8-C 32 alkyl amides; (meth)acrylic acid 10-hydroxydecyl ester, t-butyl styrene, isopropyl styrene, vinyl octanoate, vinyl nonanoate, vinyl decanoate, vinyl neodecanoate, vinyl laurate, vinyl caprolactam, (meth)acrylonitrile, isobutene, diisobutene, isoprene, vinyl chloride, vinylidene chloride, 1-allylnaphthalene, 2-allylnaphthalene, 1-vinylnaphthalene, 2-vinylnaphthalene, and combinations thereof.

20. The aqueous coating composition of any of the preceding claims, wherein the at least one core polymer is a reaction product of a1 ) and b1 ), and the at least one shell polymer is a reaction product of a2), b2), and d2); or the at least one core polymer is a reaction product of a1 ), b1 ), and e1 ), wherein a1 ) is present in an amount less than about 20 mol% of the first monomer mixture, and e1 ) is present in an amount greater than about 5 mol% of the first monomer mixture, and the at least one shell polymer is a reaction product of a2), b2), d2), and e2), wherein a2) is present in an amount less than about 20 mol% of the second monomer mixture, and e2) is present in an amount greater than about 5 mol% of the second monomer mixture. the at least one core polymer is a reaction product of a1 ), b1 ), and e1 ), wherein a1 ) is present in an amount less than about 20 mol% of the first monomer mixture, and e1 ) is present in an amount greater than about 5 mol% of the first monomer mixture, and the at least one shell polymer is a reaction product of a2), b2), d2), and e2), wherein a2) is present in an amount less than about 20 mol% of the second monomer mixture, and e2) is present in an amount greater than about 5 mol% of the second monomer mixture.

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