Gradient polymers

Abstract

Provided is a gradient polymer comprising: 5% to 35% by weight of structural units of a (meth) acrylic monomer; 35 wt% to 65 wt% of a structural unit of a C1-8 alkyl (meth) acrylate monomer; gt; 10% to 30% by weight of structural units of a dedicated associative monomer having structure (I) wherein R1 is selected from a linear saturated C12-26 alkyl group; r2 is selected from hydrogen and a methyl group, and n is from 10 to 30; 0.01 wt% to 2 wt% of a structural unit of a polyethylenically unsaturated monomer; wherein the gradient polymer comprises lt; 0.05% by weight of structural units of sulfonated monomers; wherein the gradient polymer comprises lt; 0.02% by weight of a structural unit (II) of a monomer having the structure (II) wherein R3 is selected from-H and-CH3; wherein R4 is selected from-H and a-C1-4 alkyl group; wherein R5 is selected from a-C1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a + c is 1 to 100, and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology.

Description

[0001] This invention relates to a gradient polymer. Specifically, the invention relates to a gradient polymer comprising: (a) 5% to 35% by weight (by weight) structural monomer units of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (by weight) C(meth)acrylic acid monomer based on the dry weight of the gradient polymer. 1-8 (c) Structural monomer units of alkyl ester monomers; and (d) structural monomer units of dedicated associative monomers having structure I, based on a dry weight percentage of the gradient polymer of the above-mentioned graded polymers, ranging from >10% to 30% by weight. (I) Each R 1 Independently selected from straight-chain saturated C 12-26 alkyl groups; wherein each R 2 (d) Independently selected from hydrogen and methyl groups, wherein n is 10 to 30; (d) 0.01 wt% to 2 wt% of a polyene-bonded unsaturated monomer based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.05 wt% of a sulfonated monomer based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.02 wt% of a monomer having structure II based on the dry weight of the gradient polymer. (II) Each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology.

[0002] Amino acid-based surfactants possess a range of desirable properties for use in personal care products, such as shampoos. These surfactants are typically naturally derived and readily biodegradable. They are much milder and less irritating to skin and hair compared to more traditional sulfate- and sulfonate-based surfactants such as sodium lauryl sulfate and sodium lauryl ether sulfate. They tend to exhibit lower toxicity and reduced negative environmental impact compared to more traditional sulfate- and sulfonate-based surfactants. They also possess good cleaning and foaming properties.

[0003] Nevertheless, formulations containing amino acid-based surfactants present challenges for effective thickening. Some conventional thickeners achieve their target viscosity at high usage levels, which can adversely affect foaming properties. In other cases, conventional thickeners provide sufficient thickening, but the formulation viscosity is sensitive to temperature changes; it becomes watery at high temperatures and gel-like at low temperatures. Some conventional thickeners, such as xanthan gum or cellulose esters, exhibit potential compatibility issues, leading to phase separation.

[0004] Therefore, viscosity modifiers remain in demand for water-based cleaning products that can achieve increased viscosity at low shear rates while maintaining the desired flowability at higher shear rates, particularly for water-based cleaning products containing amino acid surfactants (e.g., shampoos).

[0005] This invention provides a gradient polymer comprising: (a) 5% to 35% by weight (by weight) structural monomer units of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (by weight) C(meth)acrylic acid monomer based on the dry weight of the gradient polymer. 1-8 (c) Structural monomer units of alkyl ester monomers; and (d) structural monomer units of dedicated associative monomers having structure I, based on a dry weight percentage of the gradient polymer of the above-mentioned graded polymers, ranging from >10% to 30% by weight. (I) Each R 1 Independently selected from straight-chain saturated C 12-26 alkyl groups; wherein each R 2 (d) Independently selected from hydrogen and methyl groups, wherein n is 10 to 30; (d) 0.01 wt% to 2 wt% of a polyene-bonded unsaturated monomer based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.05 wt% of a sulfonated monomer based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.02 wt% of a monomer having structure II based on the dry weight of the gradient polymer. (II) Each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology.

[0006] This invention provides a gradient polymer comprising: (a) 5% to 35% by weight (by weight) structural monomer units of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (by weight) C(meth)acrylic acid monomer based on the dry weight of the gradient polymer. 1-8 (c) Structural monomer units of alkyl ester monomers; and (d) >10% to 30% by weight of a dedicated associating monomer having structure I based on the dry weight of the gradient polymer; wherein the structural monomer units of the dedicated associating monomer having structure I are blends of: a first dedicated associating monomer having structure Ia (Ia) Each R 1a Independently selected from straight-chain saturated C 12-19 alkyl groups; wherein each R 2a Independently selected from hydrogen and methyl groups, wherein na is 10 to 30; and a second specific associative monomer having structure Ib. (Ib) Each R 1b Independently selected from straight-chain saturated C 20-26 alkyl groups; wherein each R 2b Independently selected from straight-chain saturated hydrogen and methyl groups; and wherein nb is 10 to 30; wherein the gradient polymer comprises <0.05 wt% of sulfonated monomer structural monomer units based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.02 wt% of structural monomer units having structure II based on the dry weight of the gradient polymer; wherein each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology. Detailed Implementation

[0007] We have surprisingly discovered that gradient polymers, as described herein, are beneficial for the formulation of water-based cleaning products, particularly those containing amino acid surfactants (e.g., shampoos), to increase viscosity at low shear rates while maintaining the product's flow properties at higher shear rates.

[0008] Unless otherwise specified, ratios, percentages, parts, etc. are all by weight.

[0009] The percentage of monomer units in a polymer is the percentage of the weight of solid or pure monomers, i.e., excluding any water present in the polymer emulsion.

[0010] As used herein and in the appended claims, the term "structural monomer unit" refers to the residue of the indicated monomer; thus, the structural monomer unit of ethyl acrylate is shown: The dotted lines represent attachment points to the polymer backbone.

[0011] As used herein and in the appended claims, the term "(meth)acrylic acid" is intended to be used as a general expression to cover both acrylic acid and methacrylic acid.

[0012] As used herein and in the appended claims, the term "(meth)acrylate" is intended to be used as a general expression that covers both acrylates and methacrylates.

[0013] As used herein and in the appended claims, the term "gradient polymer morphology" refers to a polymer having a continuously varying monomer composition. The preparation of gradient polymers having a gradient polymer morphology is well known in the art. U.S. Patent 3,804,881 (in its entirety incorporated herein by reference) discloses a method for preparing a gradient polymer having a gradient polymer morphology, wherein the method comprises polymerizing at least one primary polymerizable monomer feed having different compositional contents by continuously adding at least one different secondary polymerizable monomer feed to at least one primary polymerizable monomer feed.

[0014] Preferably, the gradient polymer of the present invention comprises: (a) 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (preferably 40% to 60% by weight; more preferably 45% to 55% by weight; most preferably 48% to 54% by weight) of (meth)acrylic acid C based on the dry weight of the gradient polymer. 1-8 (c) Structural monomer units of alkyl ester monomers; and (d) structural monomer units of dedicated associative monomers having structure I, based on a dry weight basis of gradient polymers, >10% to 30% (preferably, 12% to 30%; more preferably, 15% to 25%; most preferably, 16% to 20%). (I) Each R 1 Independently selected from straight-chain saturated C12-26 alkyl group (preferably, C 12-24 Alkyl groups; more preferably, C 14-24 Alkyl group; most preferably, C 16-22 alkyl groups); wherein each R 2 Independently selected from hydrogen and methyl groups (preferably, wherein R 2 (is a methyl group), and wherein n is 10 to 30 (preferably 12 to 30; more preferably 15 to 28; most preferably 18 to 26); and (d) 0.01 wt% to 2 wt% (preferably 0.05 wt% to 1 wt%; more preferably 0.08 wt% to 0.5 wt%; most preferably 0.1 wt% to 0.2 wt%) of polyene-bonded unsaturated monomer units based on the dry weight of the gradient polymer; wherein the gradient polymer comprises <0.05 wt% ( Preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of a sulfonated monomer (e.g., AMPS) structural monomer unit; wherein the gradient polymer comprises a structural monomer unit of a monomer having structure II based on <0.02 wt% (preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of the gradient polymer on a dry weight basis. (II) Each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology. More preferably, the gradient polymer of the present invention comprises: (a) 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (preferably 40% to 60% by weight; more preferably 45% to 55% by weight; most preferably 48% to 54% by weight) of (meth)acrylic acid C based on the dry weight of the gradient polymer. 1-8(c) Structural monomer units of an alkyl ester monomer; and (d) structural monomer units of a dedicated associating monomer having structure I, based on a gradient polymer, >10% to 30% by weight (preferably 12% to 30% by weight; more preferably 15% to 25% by weight; most preferably 16% to 20% by weight); wherein the dedicated associating monomer having structure I is a blend of: a first dedicated associating monomer having structure Ia (based on the weight of the dedicated associating monomer having structure I, preferably 51% to 99% by weight; more preferably 75% to 97% by weight; most preferably 85% to 95% by weight of the first dedicated associating monomer having structure Ia). (Ia) Each R 1a Independently selected from straight-chain saturated C 12-19 Alkyl groups (preferably, straight-chain saturated C4 groups) 12-18 Alkyl groups; more preferably, straight-chain saturated C 14-18 Alkyl groups; most preferably, straight-chain saturated C 16-18 alkyl groups); wherein each R 2a Independently selected from hydrogen and methyl groups (preferably, wherein R 2 (is a methyl group), and wherein na is 10 to 30 (preferably 12 to 30; more preferably 15 to 28; most preferably 18 to 26); and a second dedicated associating monomer having structure Ib (preferably 1% to 49% by weight; more preferably 3% to 25% by weight; most preferably 6% to 15% by weight of the first dedicated associating monomer having structure Ib, based on the weight of the dedicated associating monomer having structure I). (Ib) Each R 1b Independently selected from straight-chain saturated C 20-26 Alkyl groups (preferably, straight-chain saturated C4 groups) 20-24 Alkyl groups; more preferably, straight-chain saturated C 21-23 Alkyl groups; most preferably, straight-chain saturated C 22 alkyl groups); wherein each R 2bThe structural monomer unit of the polyene-bonded unsaturated monomer is independently selected from straight-chain saturated hydrogen and methyl groups (preferably methyl groups), and wherein nb is 10 to 30 (preferably 15 to 30; more preferably 18 to 28; most preferably 20 to 28) based on the dry weight of the gradient polymer; and (d) 0.01 wt% to 2 wt% (preferably 0.05 wt% to 1 wt%; more preferably 0.08 wt% to 0.5 wt%; most preferably 0.1 wt% to 0.2 wt%) of the gradient polymer; wherein the gradient polymer comprises <0 wt% of the polyene-bonded unsaturated monomer based on the dry weight of the gradient polymer. 0.05 wt% (preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of sulfonated monomers (e.g., AMPS) structural monomer units; wherein the gradient polymer comprises <0.02 wt% (preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of structural monomer units of a monomer having structure II based on the dry weight of the gradient polymer, wherein each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology.

[0015] Preferably, the gradient polymer of the present invention comprises 90% to 100% by weight (preferably 95% to 100% by weight; more preferably 98% to 100% by weight; still more preferably 99% to 100% by weight; even more preferably 99.9% to 100% by weight; most preferably 100% by weight) of structural monomer units present in the gradient polymer, said structural monomer units being the structural monomer units of (a)-(d). The structural monomer units of the gradient polymer do not include end groups (e.g., residues of chain transfer agents) derived from chain transfer agents or initiators on the gradient polymer.

[0016] Preferably, the gradient polymer of the present invention comprises 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of a (meth)acrylic acid monomer based on the dry weight of the gradient polymer; wherein the (meth)acrylic acid monomer is selected from the group consisting of methacrylic acid, acrylic acid, and mixtures thereof. More preferably, the gradient polymer of the present invention comprises 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of a (meth)acrylic acid monomer based on the dry weight of the gradient polymer; wherein the (meth)acrylic acid monomer is a mixture of methacrylic acid and acrylic acid. Most preferably, the gradient polymer of the present invention comprises structural monomer units of (meth)acrylic acid monomers based on 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of the gradient polymer on a dry weight basis; wherein the (meth)acrylic acid monomers are a mixture of 30% to 60% by weight (preferably 32% to 58% by weight; more preferably 33% to 55% by weight) of methacrylic acid and 40% to 70% by weight (preferably 32% to 58% by weight; more preferably 33% to 55% by weight) of acrylic acid based on a weight basis of the mixture.

[0017] Preferably, the gradient polymer of the present invention comprises 35% to 65% (preferably 40% to 60% by weight; more preferably 45% to 55% by weight; most preferably 48% to 54% by weight) of (meth)acrylic acid C based on the dry weight of the gradient polymer. 1-8 Alkyl ester monomer (preferably, (meth)acrylic acid C) 1-6 Alkyl ester monomer; more preferably, (meth)acrylic acid C 2-3 The structural unit is an alkyl ester monomer; most preferably, a C2 alkyl ester monomer of acrylic acid. More preferably, the gradient polymer of the present invention comprises 35% to 65% (preferably 40% to 60% by weight; more preferably 45% to 55% by weight; most preferably 48% to 54% by weight) of (meth)acrylic acid C2 ester monomer based on the dry weight of the gradient polymer. 1-8 The structural unit of alkyl ester monomers; wherein (meth)acrylic acid C 1-8The alkyl ester monomer is selected from the group consisting of ethyl (meth)acrylate, propyl (meth)acrylate, and mixtures thereof (preferably ethyl acrylate, propyl acrylate, and mixtures thereof). Most preferably, the gradient polymer of the present invention comprises 35% to 65% (preferably 40% to 60%; more preferably 45% to 55%; most preferably 48% to 54%) of (meth)acrylate C based on the dry weight of the gradient polymer. 1-8 The structural unit of alkyl ester monomers; wherein (meth)acrylic acid C 1-8 The alkyl ester monomer is ethyl acrylate.

[0018] Preferably, the gradient polymer of the present invention comprises >10% to 30% by weight (preferably 12% to 30% by weight; more preferably 15% to 25% by weight; most preferably 16% to 20% by weight) of a dedicated associative monomer having structure I based on the dry weight of the gradient polymer. (I) Each R 1 Independently selected from straight-chain saturated C 12-26 alkyl group (preferably, C 12-24 Alkyl groups; more preferably, C 14-24 Alkyl group; most preferably, C 16-22 alkyl groups); wherein each R 2 Independently selected from hydrogen and methyl groups (preferably, wherein R 2 (is a methyl group), and wherein n is 10 to 30 (preferably 12 to 30; more preferably 15 to 28; most preferably 18 to 26). More preferably, the gradient polymer of the present invention comprises >10% to 30% by weight (preferably 12% to 30% by weight; more preferably 15% to 25% by weight; most preferably 16% to 20% by weight) of a dedicated associating monomer having structure I based on the dry weight of the gradient polymer; wherein the dedicated associating monomer having structure I is a blend of: a first dedicated associating monomer having structure Ia (preferably 51% to 99% by weight; more preferably 75% to 97% by weight; most preferably 85% to 95% by weight of the first dedicated associating monomer having structure Ia based on the weight of the dedicated associating monomer having structure I). (Ia) Each R 1a Independently selected from straight-chain saturated C 12-19 Alkyl groups (preferably, straight-chain saturated C4 groups) 12-18 Alkyl groups; more preferably, straight-chain saturated C 14-18Alkyl groups; most preferably, straight-chain saturated C 16-18 alkyl groups); wherein each R 2a Independently selected from hydrogen and methyl groups (preferably, wherein R 2 (is a methyl group), and wherein na is 10 to 30 (preferably 12 to 30; more preferably 15 to 28; most preferably 18 to 26); and a second dedicated associating monomer having structure Ib (preferably 1% to 49% by weight; more preferably 3% to 25% by weight; most preferably 6% to 15% by weight of the first dedicated associating monomer having structure Ib, based on the weight of the dedicated associating monomer having structure I). (Ib) Each R 1b Independently selected from straight-chain saturated C 20-26 Alkyl groups (preferably, straight-chain saturated C4 groups) 20-24 Alkyl groups; more preferably, straight-chain saturated C 21-23 Alkyl groups; most preferably, straight-chain saturated C 22 alkyl groups); wherein each R 2b Independently selected from straight-chain saturated hydrogen and methyl groups (preferably methyl groups); and wherein nb is 10 to 30 (preferably 15 to 30; more preferably 18 to 28; most preferably 20 to 28) (preferably, wherein R 1a and R 1b The difference is less than 8 carbon atoms (more preferably, less than 7 carbon atoms).

[0019] Preferably, the gradient polymer of the present invention comprises structural monomer units of a polyene-bonded unsaturated monomer based on a dry weight of 0.01 wt% to 2 wt% (preferably, 0.05 wt% to 1 wt%; more preferably, 0.08 wt% to 0.5 wt%; most preferably, 0.1 wt% to 0.2 wt%) of the gradient polymer. More preferably, the gradient polymer of the present invention comprises structural monomer units of a polyene-bonded unsaturated monomer based on a dry weight of 0.01 wt% to 2 wt% (preferably, 0.05 wt% to 1 wt%; more preferably, 0.08 wt% to 0.5 wt%; most preferably, 0.1 wt% to 0.2 wt%) of the gradient polymer; wherein the polyene-bonded unsaturated monomer is selected from the group consisting of: polyunsaturated aromatic monomers (e.g., divinylbenzene, divinylnaphthalene, trivinylbenzene); polyunsaturated aromatic monomers; ... Saturated alicyclic monomers (e.g., 1,2,4-trivinylcyclohexane); difunctional esters of phthalic acid (e.g., diallyl phthalate); polyunsaturated alicyclic monomers (e.g., isoprene, butadiene, 1,5-hexadiene, 1,5,9-decanetriene, 1,9-decadiene, 1,5-heptadiene); polyolefin ethers (e.g., triallyl pentaerythritol, diallyl pentaerythritol, diallyl sucrose, octaallyl sucrose, trimethylolpropane diallyl ether); polyunsaturated alicyclic monomers of polyols or polyacids. Saturated esters (e.g., 1,6-hexanediol di(meth)acrylate, tetramethylene tri(meth)acrylate, allyl acrylate, diallyl itaconic acid, diallyl fumarate, diallyl maleate, trimethylolpropane tri(meth)acrylate, trimethylolpropane di(meth)acrylate, polyethylene glycol di(meth)acrylate); alkylene bisacrylamides (e.g., methylene bisacrylamide, propylene bisacrylamide); hydroxyl and carboxyl derivatives of methylene bisacrylamide (e.g., N... N'-bis(hydroxymethyl)methylenebisacrylamide); polyethylene glycol di(meth)acrylates (e.g., ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate); polyunsaturated silanes (e.g., dimethyldivinylsilane, methyltrivinylsilane, allyl dimethylvinylsilane, diallyl dimethylsilane, tetravinylsilane); polyunsaturated tinanes (e.g., tetraallyltin, diallyl dimethyltin); and mixtures thereof. More preferably, the gradient polymer of the present invention comprises 0.01% to 2% (preferably, 0.05% to 1%; more preferably, 0.08% to 0.5%; most preferably, 0.1% to 0.2%) of a polyene-bonded unsaturated monomer based on the dry weight of the gradient polymer; wherein the polyene-bonded unsaturated monomer is a polyene ether.Most preferably, the gradient polymer of the present invention comprises a structural monomer unit of a polyene-bonded unsaturated monomer based on a dry weight of 0.01 wt% to 2 wt% (preferably, 0.05 wt% to 1 wt%; more preferably, 0.08 wt% to 0.5 wt%; most preferably, 0.1 wt% to 0.2 wt%) of the gradient polymer; wherein the polyene-bonded unsaturated monomer is trimethylolpropane diallyl ether.

[0020] Preferably, the gradient polymer of the present invention further comprises 0.01 wt% to 2 wt% (preferably 0.02 wt% to 1 wt%; more preferably 0.04 wt% to 0.5 wt%; most preferably 0.06 wt% to 0.1 wt%) of residues of a chain transfer agent based on the dry weight of the gradient polymer. More preferably, the gradient polymer of the present invention further comprises 0.01 wt% to 2 wt% (preferably 0.02 wt% to 1 wt%; more preferably 0.04 wt% to 0.5 wt%; most preferably 0.06 wt% to 0.1 wt%) of residues of a chain transfer agent based on the dry weight of the gradient polymer; wherein the chain transfer agent is selected from the group consisting of: sulfur-containing and disulfide compounds (e.g., C 1-18 Alkyl thiols, mercaptocarboxylic acids, mercaptocarboxylic esters, thioesters, C 1-18 Alkyl disulfides, aryl disulfides, polyfunctional thiols); phosphites and hypophosphites; haloalkyl compounds (e.g., carbon tetrachloride, chloroform); unsaturated chain transfer agents (e.g., α-methylstyrene); and mixtures thereof. More preferably, the gradient polymer of the present invention further comprises 0.01% to 2% by weight (preferably 0.02% to 1% by weight; more preferably 0.04% to 0.5% by weight; most preferably 0.06% to 0.1% by weight) residues of a chain transfer agent based on the dry weight of the gradient polymer; wherein the chain transfer agent is C 1-18 Alkyl mercaptan. Most preferably, the gradient polymer of the present invention further comprises 0.01% to 2% by weight (preferably 0.02% to 1% by weight; more preferably 0.04% to 0.5% by weight; most preferably 0.06% to 0.1% by weight) of a chain transfer agent residue based on the dry weight of the gradient polymer; wherein the chain transfer agent is n-dodecyl mercaptan.

[0021] Preferably, the gradient polymer of the present invention comprises a structural monomer unit of a sulfonated monomer based on a dry weight of <0.05% by weight (preferably, <0.01% by weight; more preferably, <0.001% by weight; still more preferably, <0.0001% by weight; most preferably, less than the detectable limit) of the gradient polymer; wherein the sulfonated monomer is selected from the group consisting of: 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2-methacrylamido-2-methylpropanesulfonic acid, 4-styrenesulfonic acid, vinylsulfonic acid, 3-allyloxysulfonic acid, 2-hydroxy-1-propanesulfonic acid (HAPS), 2-sulfoethyl(meth)acrylic acid, 2-sulfopropyl(meth)acrylic acid, 3-sulfopropyl(meth)acrylic acid, 4-sulfobutyl(meth)acrylic acid, salts thereof, and mixtures thereof.

[0022] Preferably, the gradient polymer of the present invention comprises structural monomer units of a monomer having structure II, in an amount of <0.02 wt% (preferably <0.01 wt%; more preferably <0.001 wt%; still more preferably <0.0001 wt%; most preferably, less than the detectable limit) based on the dry weight of the gradient polymer. (II) Each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4.

[0023] Preferably, the gradient polymer of the present invention comprises, based on a dry weight of <0.01 wt% (preferably, <0.005 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of structural monomer units of monomers selected from the group consisting of: styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, and mixtures thereof.

[0024] Preferably, the gradient polymer of the present invention comprises <2% by weight (preferably <1% by weight; more preferably <0.5% by weight; still more preferably <0.1% by weight; even more preferably <0.01% by weight; still even more preferably <0.001% by weight; most preferably, less than the detectable limit) of a monomer selected from the group consisting of: (meth)acrylic acid C 6-18Alkyl esters, vinyl alkyl esters having 6 to 18 carbon atoms, N-vinylalkylamides having 6 to 18 carbon atoms, N-alkyl (meth)acrylamides having 6 to 18 carbon atoms, and mixtures thereof.

[0025] Preferably, the gradient polymer of the present invention comprises: (a) 5% to 35% by weight (preferably 10% to 35% by weight; more preferably 20% to 34% by weight; most preferably 26% to 32% by weight) of (meth)acrylic acid monomer based on the dry weight of the gradient polymer; and (b) 35% to 65% by weight (preferably 40% to 60% by weight; more preferably 45% to 55% by weight; most preferably 48% to 54% by weight) of (meth)acrylic acid C based on the dry weight of the gradient polymer. 1-8 (c) Structural monomer units of alkyl ester monomers; (d) Structural monomer units of a dedicated associating monomer having structure I, based on a dry weight basis of a gradient polymer, >10% to 30% (preferably 12% to 30%; more preferably 15% to 25%; most preferably 16% to 20%); wherein the dedicated associating monomer having structure I is a blend of: a first dedicated associating monomer having structure Ia (based on the weight of the dedicated associating monomer having structure I, preferably 51% to 99%; more preferably 75% to 97%; most preferably 85% to 95% of the first dedicated associating monomer having structure Ia), wherein each R 1a Independently selected from straight-chain saturated C 12-19 Alkyl groups (preferably, straight-chain saturated C4 groups) 12-18 Alkyl groups; more preferably, straight-chain saturated C 14-18 Alkyl groups; most preferably, straight-chain saturated C 16-18 alkyl groups); wherein each R 2a Independently selected from hydrogen and methyl groups (preferably, wherein R 2 (is a methyl group), and wherein na is 10 to 30 (preferably 12 to 30; more preferably 15 to 28; most preferably 18 to 26); and a second dedicated associating monomer having structure Ib (based on the weight of the dedicated associating monomer having structure I, preferably 1% to 49% by weight; more preferably 3% to 25% by weight; most preferably 6% to 15% by weight of the first dedicated associating monomer having structure Ib), wherein each R 1b Independently selected from straight-chain saturated C 20-26 Alkyl groups (preferably, straight-chain saturated C4 groups) 20-24 Alkyl groups; more preferably, straight-chain saturated C 21-23 Alkyl groups; most preferably, straight-chain saturated C 22alkyl groups); wherein each R 2b The structural monomer unit of the polyene-bonded unsaturated monomer is independently selected from straight-chain saturated hydrogen and methyl groups (preferably methyl groups), and wherein nb is 10 to 30 (preferably 15 to 30; more preferably 18 to 28; most preferably 20 to 28) based on the dry weight of the gradient polymer; and (d) 0.01 wt% to 2 wt% (preferably 0.05 wt% to 1 wt%; more preferably 0.08 wt% to 0.5 wt%; most preferably 0.1 wt% to 0.2 wt%) of the gradient polymer; wherein the gradient polymer comprises <0 wt% of the polyene-bonded unsaturated monomer based on the dry weight of the gradient polymer. 0.05 wt% (preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of sulfonated monomers (e.g., AMPS) structural monomer units; wherein the gradient polymer comprises <0.02 wt% (preferably, <0.01 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of structural monomer units of a monomer having structure II based on the dry weight of the gradient polymer, wherein each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl groups; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100, and wherein d is 1 to 4; wherein the gradient polymer has a gradient polymer morphology; and has one or more of the following conditions (i)-(v): (i) wherein R 1a and R 1b(ii) wherein the structural monomer unit of the (meth)acrylic acid monomer comprises structural monomer units of both methacrylic acid and acrylic acid; (iii) wherein the gradient polymer comprises, based on the dry weight of the gradient polymer, <0.01 wt% (preferably, <0.005 wt%; more preferably, <0.001 wt%; still more preferably, <0.0001 wt%; most preferably, less than the detectable limit) of structural monomer units of monomers selected from the group consisting of: styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate, and mixtures thereof; (iv) wherein the gradient polymer comprises, based on the dry weight of the gradient polymer, <2 wt% (preferably, <1 wt%; more preferably, <0.5 wt%; still more preferably, <0.1 wt%; even more preferably, < 0.01 wt%; more preferably, <0.001 wt%; most preferably, less than the detectable limit) of structural monomer units selected from the group consisting of: alkyl (meth)acrylates having 6 to 18 carbon atoms, vinyl alkyl esters having 6 to 18 carbon atoms, N-vinylalkylamides having 6 to 18 carbon atoms, N-alkyl (meth)acrylamides having 6 to 18 carbon atoms, and mixtures thereof; and / or (v) wherein the gradient polymer contains 90 wt% to 100 wt% (preferably, 95 wt% to 100 wt%; more preferably, 98 wt% to 100 wt%; still more preferably, 99 wt% to 100 wt%; even more preferably, 99.9 wt% to 100 wt%; most preferably, 100 wt%) of structural monomer units present in the gradient polymer, said structural monomer units being the structural monomer units of (a)-(d).

[0026] Some embodiments of the present invention will now be described in detail in the following examples. Synthesis of S1: Gradient Polymer

[0027] Add deionized water (350 g) and sodium lauryl sulfate (9.1 g) to a 3 L, 4-necked round-bottom reactor equipped with a mechanical stirrer, thermocouple, condenser, and nitrogen injector. Purge the reactor with nitrogen and heat to 85 °C. Prepare the following separately: (1) Prepare monomeric emulsion A from the following: deionized water (450 g); sodium lauryl sulfate (16.4 g); ethyl acrylate (EA) (262 g); lipophilic modified monomer (Lipo 1) having the following structure (82.1 g). Where R 1 It is a straight-chain saturated C 16-18Alkyl groups, and n is an average of 18 to 26; a lipophilic modified monomer (Lipo 2) with the following structure (9.6 g). Where R 1 It is a straight-chain saturated C 22 Alkyl groups, and n is an average of 20 to 28; methacrylic acid (MAA) A (45.68g); acrylic acid (AA) (101.1g) and n-dodecyl mercaptan (n-DDM) (0.4g); (2) Monomer emulsion additive B is prepared by: deionized water (70g); sodium lauryl sulfate (9.1g); trimethylolpropane diallyl ether (x-link) (0.81g) and methacrylic acid (MAA) B (3) Initiator solution (C1) was prepared by dissolving ammonium persulfate (0.35 g) in deionized water (15 g), and (4) Initiator solution (C2) was prepared by dissolving ammonium persulfate (0.55 g) in deionized water (84 g). Initiator solution (C1) was added to the reactor at a reactor temperature of about 85°C. Monomer emulsion (A) was then added to the reactor, and monomer emulsion additive (B) was added to monomer emulsion (A) at the same time. The feed rate was controlled such that the feed of monomer emulsion (A) started at half the rate during the first 10 minutes and started at 1 the rate until it ended at 120 min, and the feed of monomer emulsion additive (B) ended within 100 min. At the same time, initiator solution (C2) was fed into the reactor within 125 min. After these additions are completed, the monomer emulsion and initiator feed line are rinsed with deionized water, followed by monomer scavenging with a free radical catalyst and activator. Synthesis of S2-S4: Gradient Polymers

[0028] The gradient polymers in synthesized S2-S4 were prepared according to the procedure described in synthesis S1, except that the composition varied as shown in Table 1. Synthesis of S5: Non-gradient polymer

[0029] Deionized water (275 g) and sodium lauryl sulfate (9.1 g) were added to a 3 L, 4-necked round-bottom reactor equipped with a mechanical stirrer, thermocouple, condenser, and nitrogen injector. The reactor was purged with nitrogen and heated to 85 °C. The following items were prepared separately: (1) Monomer emulsion A was prepared from the following: deionized water (570 g); sodium lauryl sulfate (25.5 g); ethyl acrylate (EA) (262 g); and a lipophilic modified monomer (Lipo 1) having the following structure (82.1 g). Where R 1 It is a straight-chain saturated C 16-18 Alkyl groups, and n is an average of 18 to 26; a lipophilic modified monomer (Lipo 2) with the following structure (9.6 g). Where R 1 It is a straight-chain saturated C 22 Alkyl groups, and n is an average of 20 to 28; methacrylic acid (MAA) (50.5 g); acrylic acid (AA) (101.1 g); n-dodecyl mercaptan (n-DDM) (0.4 g) and trimethylolpropane diallyl ether (x-link) (0.81 g); (2) an initiator solution (C1) was prepared by dissolving ammonium persulfate (0.35 g) in deionized water (15 g), and (3) an initiator solution (C2) was prepared by dissolving ammonium persulfate (0.55 g) in deionized water (84 g). The initiator solution (C1) was charged into the reactor at a reactor temperature of about 85 °C. The monomer emulsion (A) was then charged into the reactor. The rate was controlled such that the feed of monomer emulsion (A) started at half the rate during the first 10 minutes and started at half the rate until it ended at 120 min. Individually, the initiator solution (C1) and monomer emulsion (A) were fed into the reactor simultaneously and within 125 min. After these additions were complete, the monomer and initiator feed lines were flushed with deionized water, followed by monomer removal with a radical catalyst and activator. Synthesis of S6-S8: Non-gradient polymers

[0030] The non-gradient polymers in synthesized S6-S8 were prepared according to the procedure described in synthesis S5, except that the composition was varied as described in Table 2. Viscosity and turbidity measurement

[0031] For each polymer prepared according to the synthesizers S1-S8 reported in Table 3, the solubility viscosity and turbidity of a solution containing 0.75% of the polymer active material were determined using the following procedure: 1. Weigh out enough polymer to provide 0.75% polymer in the final formulation. 2. Pre-dilute with deionized water to prepare a 169g solution. 3. Add 11.0 g of 20% w / w sodium hydroxide aqueous solution and stir effectively with a top stirrer until homogeneous. 4. Equilibrate in a warm water bath for 10-15 minutes. Therefore, the internal temperature of the solution is 20℃. 5. The measured pH should be between 7.8 and 10. Adjust with 20% sodium hydroxide if necessary. 6. Use a Brinell viscometer with a corresponding spindle to measure viscosity at 20°C and at 0.3 rpm, 3 rpm, 6 rpm, 12 rpm, 20 rpm, 30 rpm and 60 rpm to obtain measurement results with a scale of at least 10%. 7. Transfer the sample to a 1oz vial for turbidity measurement. 8. Centrifuge the 1oz vial at 3,500 rpm for 20 minutes. 9. Measure the turbidity in turbidity units (NTU) using a turbidimeter at 20°C. The results of viscosity and turbidity measurements are reported in Table 3. Comparative Examples CF1-CF6 and Examples F1-F6: Cleaning Formulations

[0032] Aqueous personal care cleaning formulations were prepared in each of Comparative Examples CF1-CF6 and Examples F1-F6 having the formulations shown in Table 4.

[0033] The phase A components (if any) of each of Comparative Examples CF1-CF6 and Examples F1-F6 were mixed with gentle stirring until dissolved. The phase B components were mixed together in a separate container. The mixed phase B components were then slowly added to the mixed phase A components (if any). The phase C components were then added to the mixed phase A components (if any) and phase B components. The appropriate amount of phase D components was then mixed as needed to adjust to the pH shown in Table 4. The viscosity of the resulting aqueous personal care cleaning formulation was then measured at 20°C using a Brookfield viscometer with the corresponding principal axis, as listed in Table 5. Comparative Examples CF7-CF10 and Examples F7-F10: Cleaning Formulations

[0034] Aqueous personal care cleaning formulations were prepared in each of Comparative Examples CF7-CF10 and Examples F7-F10, having formulations shown in Table 6. Phase A components were mixed together. Then, the mixed Phase B component was slowly added to the mixed Phase A component. Appropriate Phase C components were mixed into the mixed Phase A and Phase B components as needed to adjust the pH. The viscosity of the resulting aqueous personal care cleaning formulations was then measured at 20 rpm and 20°C using a Brookfield viscometer with corresponding spindles, as listed in Table 7. The turbidity of each formulation was measured using a Micro 100 turbidimeter (HF Scientific, Inc.), as listed in Table 7. Rheological data

[0035] The rheological properties of the aqueous personal care cleaning formulations prepared according to Comparative Examples CF7-CF10 and Examples F7-F10 were characterized using a Discovery HR-3 hybrid rheometer (TA Instruments) with a 40 mm parallel plate geometry. All tests were performed at 25 °C. The tests included amplitude scans with oscillation displacements of 0.0002 rad to 0.15 rad at 1 rad / s and shear rates of 0.01 s⁻¹. -1 up to 500s -1 The flow scans were performed. The values ​​of G', G'', and tanδ were obtained from the amplitude in the linear viscoelastic region, and the viscosity values ​​were obtained from the shear rate scans, as listed in Table 8.

Claims

1. A gradient polymer comprising: (a) 5 to 35 weight percent of structural monomer units of (meth)acrylic monomers, based on the dry weight of the gradient polymer; (b) 35 to 65% by weight, based on the dry weight of the gradient polymer, of a C 1-8 monomer units of a C1-8 alkyl ester monomer; (c) > 10 to 30 weight percent of structural monomer units of a dedicated associative monomer having Structure I, based on the dry weight of the gradient polymer (I) wherein each R is independently selected from a linear saturated C 1 independently selected from a linear saturated C 12-26 alkyl group; wherein each R is independently selected from a linear saturated C 2 independently selected from hydrogen and a methyl group, and wherein n is 10 to 30; (d) 0.01 to 2 weight percent of structural monomer units of a multiethylenically unsaturated monomer, based on the dry weight of the gradient polymer; wherein the gradient polymer comprises < 0.05 weight percent of structural monomer units of a sulfonated monomer, based on the dry weight of the gradient polymer; wherein the gradient polymer comprises < 0.02 weight percent of structural monomer units of a monomer having Structure II, based on the dry weight of the gradient polymer (I) and (II) Each R 3 Independently selected from -H and -CH3; where each R 4 Independently selected from -H and -C 1-4 alkyl groups; wherein each R 5 Independently selected from -C 1-4 Alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a+c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymer morphology.

2. The gradient polymer of claim 1, wherein the structural monomer units of a dedicated associative monomer having Structure I are a blend of a first dedicated associative monomer having Structure la (Ia) wherein each R is independently selected from a linear saturated C 1a 12-19 alkyl group; wherein each R is independently selected from a linear saturated C 2a is independently selected from hydrogen and a methyl group, and wherein na is 10 to 30; and​ a second dedicated associative monomer having Structure lb (Ib) wherein each R is independently selected from a linear saturated C 1b independently selected from a linear saturated C 20-26 alkyl group; wherein each R is independently selected from a linear saturated C 2b independently selected from a linear saturated C independently selected from a linear saturated C 3. The gradient polymer of claim 1, wherein the structural monomer units of (meth)acrylic monomers include structural monomer units of both methacrylic acid and acrylic acid.

4. The gradient polymer of claim 1, wherein the gradient polymer comprises < 0.01 weight percent of structural monomer units of a monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate, and mixtures thereof, based on the dry weight of the gradient polymer.

5. The gradient polymer of claim 1, wherein the gradient polymer comprises < 2 weight percent of a monomer selected from the group consisting of (meth)acrylic alkyl esters having 6 to 18 carbons, vinyl alkanoates having 6 to 18 carbon atoms, N-vinyl alkyl amides having 6 to 18 carbon atoms, N-alkyl (meth)acrylamides having 6 to 18 carbon atoms, and mixtures thereof, based on the dry weight of the gradient polymer.

6. The gradient polymer of claim 1, wherein the gradient polymer comprises 90 to 100 weight percent of structural monomer units present in the gradient polymer that are structural monomer units of (a)-(d).

7. The gradient polymer of claim 2, wherein the gradient polymer comprises < 0.01 weight percent of structural monomer units of a monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate, and mixtures thereof, based on the dry weight of the gradient polymer.

8. The gradient polymer of claim 2, wherein R 1a and R 1b differ by less than 8 carbon atoms.

9. The gradient polymer of claim 2, wherein the gradient polymer comprises < 2 wt.% of structural monomer units of monomers selected from the group consisting of (meth)acrylic alkyl esters having 6 to 18 carbons, vinyl alkanoates having 6 to 18 carbon atoms, N-vinyl alkyl amides having 6 to 18 carbon atoms, N-alkyl (meth)acrylamides having 6 to 18 carbon atoms, and mixtures thereof, based on the dry weight of the gradient polymer.

10. The gradient polymer of claim 2, having any one or more of conditions (i)-(v) below: (i) where R 1a and R 1b differ by less than 8 carbon atoms; (ii) wherein the structural monomer units of the (meth)acrylic monomers include structural monomer units of both methacrylic acid and acrylic acid; (iii) wherein the gradient polymer comprises < 0.01 wt.% of structural monomer units of monomers selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate, and mixtures thereof, based on the dry weight of the gradient polymer; (iv) wherein the gradient polymer comprises < 2 wt.% of structural monomer units of monomers selected from the group consisting of (meth)acrylic alkyl esters having 6 to 18 carbons, vinyl alkanoates having 6 to 18 carbon atoms, N-vinyl alkyl amides having 6 to 18 carbon atoms, N-alkyl (meth)acrylamides having 6 to 18 carbon atoms, and mixtures thereof, based on the dry weight of the gradient polymer; and / or (v) wherein the gradient polymer comprises 90 wt.% to 100 wt.% of structural monomer units present in the gradient polymer that are structural monomer units of (a)-(d).

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