Seed resin stabilized high solids emulsion polymer

Abstract

The currently claimed invention relates to polymer emulsions and methods for preparing polymer emulsions. In particular, the currently claimed invention relates to methods for preparing polymer emulsions with high solids content.

Description

Technical Field

[0001] The currently claimed invention relates to polymer emulsions and methods for preparing polymer emulsions. In particular, the currently claimed invention relates to methods for preparing polymer emulsions with high solids content. Background Technology

[0002] Stable polymer emulsions are widely used in printing and packaging, especially as adhesives. Particularly due to environmental regulations, there is a growing demand for adhesives based on waterborne polymer emulsions with superior performance compared to traditional hot-melt and solvent-based adhesives. More specifically, water-based adhesive systems offer advantages in terms of reduced organic solvent emissions.

[0003] During adhesive preparation, the aqueous medium is typically removed from the emulsion, and the adhesive is then cured and hardened at room temperature to form a binder, ideally possessing high strength and resistance to heat, moisture, and water. However, high water content often introduces unnecessary costs and complexities to the drying and film formation of the water system. Therefore, a dispersion with the highest possible solids content and low water content is required, which will provide faster setting times for the use of high-speed production equipment. Thus, one way to improve adhesive performance parameters (such as setting speed, peel strength, water resistance, and smoothness) is to increase the solids content of the emulsion. Furthermore, it remains necessary to balance the high solids content in the emulsion with its viscosity to maintain processability, i.e., to allow it to be applied using conventional equipment.

[0004] Polymer emulsions are typically prepared by emulsion polymerization in the presence of a non-polymerizing emulsifier. Exemplary methodologies for their preparation are described in U.S. patents: 4,921,898; 5,070,134 and 5,629,370. The methods described in these patents are to be understood by those skilled in the art as unsuitable for preparing polymer emulsions with high solids content greater than about 65 wt.%.

[0005] Recently, polymer dispersions or polymer emulsions with high solids content for use in coatings have been studied. For example, polymer emulsions with high solids content are known and described, for example, in the following references.

[0006] US2015 / 0284482 describes a method for preparing an aqueous polymer dispersion with high solids content, wherein the dispersed polymer is prepared by free radical emulsion polymerization in the presence of a polymer protective colloid.

[0007] US2007 / 0255000 describes an aqueous dispersion of polymer particles comprising: 5% to 80% by weight of a first polymer, the first polymer comprising at least one copolymerized olefinically unsaturated monomer, based on the weight of the polymer particles; and 20% to 95% by weight of a second polymer substantially encapsulating the first polymer, the second polymer comprising at least one copolymerized olefinically unsaturated monomer, the second polymer having a Tg of -40°C to 30°C, wherein at least 90% by weight of the second polymer is formed by polymerization at a temperature of 5°C to 65°C.

[0008] EP 2 058 364 describes a composition comprising a water-based polymer binder, wherein the binder comprises, by weight of total polymer solids, from 0.05 wt.% to 20 wt.% carboxylic acid monomers present as comonomers in pendant polyacid sidechain groups, wherein the calculated glass transition temperature Tg of the binder is between -50°C and 80°C; fillers, wherein the dry weight ratio of fillers to polymer is from 1:1 to 10:1; and a thickener, in an amount sufficient to achieve a shear-thinning composition having a Brookfield viscosity between 200,000 cps and 10,000,000 cps when not under shear conditions, wherein the volume solids of the composition are from about 50% to about 75%.

[0009] US 4,921,898 discloses a vinyl acetate-ethylene copolymer emulsion containing about 65% to 70% solids and prepared in the presence of a stable system with a viscosity of less than about 3,500 cps.

[0010] While the aforementioned references describe emulsions with high solids content, they have limitations. For example, the presence of other components in the emulsion can restrict its application. Emulsifiers or polymer emulsions based on specific surfactant systems exhibit adverse effects on performance properties. In some known embodiments, protective colloids are used instead of emulsifiers in the polymer emulsion; however, these protective colloids have certain drawbacks. For instance, protective colloids are typically low molecular weight polymers containing acid groups, which become water-soluble under elevated pH conditions when the acid groups are neutralized. Furthermore, these systems containing protective colloids suffer from the presence of significant amounts of stabilizers, thus limiting water repellency. Additionally, polymer emulsions containing protective colloids and having high solids content exceeding 55 wt.% often exhibit poor rheological properties and are too viscous or lack sufficient flowability, making them unsuitable for coating on substrates.

[0011] Further improvements in this field include the use of block copolymers with different hydrophobic and hydrophilic blocks. However, these systems are generally limited to emulsions with relatively low solid content, thus limiting their availability in industrial applications.

[0012] Therefore, there is a clear need for improved polymer emulsions with low or almost no emulsifier content, and emulsions with high solids content and improved performance properties. Therefore, the object of the currently claimed invention is to provide an improved method for preparing polymer emulsions that overcomes the aforementioned disadvantages and eliminates the need for surfactants to stabilize the polymer emulsion. Another object of the invention is to provide a method for preparing polymer emulsions with a high solids content greater than 55 wt.%, which exhibits improved application performance compared to surfactant-based emulsions. Summary of the Invention

[0013] Surprisingly, it has been found that polymeric mixtures containing at least one copolymerizable monomer and a resin dispersion, through the polymerization of polymer seeds, can be used to prepare polymer emulsions as disclosed herein, resulting in polymer emulsions with a high solids content of at least 55 wt.%. Furthermore, the methods for preparing polymer emulsions disclosed herein can yield polymer emulsions with low viscosity, wherein the particles forming the emulsion exhibit a bimodal or multimodal particle size distribution.

[0014] This invention relates to a method for preparing a polymer emulsion, the method comprising the steps of: providing a resin dispersion having at least one resin in water, and adding at least one polymer seed and a polymerization mixture to the resin dispersion. The polymerization mixture has at least one copolymerizable monomer. The method comprises preparing a polymer emulsion in water by free radical emulsion polymerization of the polymerization mixture, the resin dispersion, and the polymer seed. Based on the total weight of the polymer emulsion, the polymer emulsion has a solid content of at least 55 wt.%.

[0015] According to another aspect of the invention, a polymer emulsion is provided that can be obtained by the methods disclosed herein. Detailed Implementation

[0016] This disclosure is not limited to the specific embodiments described herein. Many modifications and variations can be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of this disclosure, other than those listed herein, will become apparent to those skilled in the art based on the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims and the entire scope of equivalents obtained by granting those claims. It should be understood that this disclosure is not limited to specific methods, reagents, compounds, or compositions, which may of course be varied. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be restrictive.

[0017] As used herein, the terms “comprising” and “comprised of” are synonymous with “including” or “containing” and are inclusive or open-ended, not excluding additional, unlisted members, elements, or method steps. It should be understood that, as used herein, the term “comprising / comprises / comprised of” includes the terms “consisting of”, “consists”, and “consists of”.

[0018] Furthermore, the terms “first,” “second,” “third,” or “(a),” “(b),” “(c),” “(d),” etc., used in the specification and claims are used to distinguish similar elements and are not necessarily used to describe order or temporal sequence. It should be understood that such terms are interchangeable where appropriate, and embodiments of the invention described herein can be operated in a different order than that described or illustrated herein. Where the terms “first,” “second,” “third,” or “(A),” “(B),” and “(C),” or “(a),” “(b),” “(c),” “(d),” “(i),” “(ii),” etc., relate to steps of a method, use, or measurement, there is no temporal or time interval continuity between the steps; that is, these steps may be performed simultaneously, or there may be time intervals of seconds, minutes, hours, days, weeks, months, or even years between such steps, unless otherwise indicated in the application set forth above or below.

[0019] Furthermore, when features or aspects of this disclosure are described in accordance with the Markush Group, those skilled in the art will recognize that this disclosure is also described in accordance with any individual member or subgroup of the Markush Group.

[0020] For the purposes of this invention, all scopes disclosed herein also cover any and all possible subscopes and combinations thereof. Furthermore, scopes defined throughout the specification also include end values; that is, a scope of 1 to 10 means that the scope includes both 1 and 10. For the avoidance of doubt, the applicant has the right to enjoy equivalents under applicable law. Any listed scope can be readily considered sufficiently descriptive and achieves the same scope being decomposed into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting embodiment, each scope discussed herein can be readily decomposed into lower thirds, middle thirds, and upper thirds, etc. As those skilled in the art will also understand, all languages ​​such as “at most,” “at least,” “greater than,” “less than,” etc., include the stated numbers and refer to a scope that can be subsequently decomposed into subscopes as discussed above. Finally, as those skilled in the art will understand, a scope includes each individual member. Thus, for example, a group having 1-3 cells means a group having 1, 2, or 3 cells. Similarly, a group having 1-5 cells means a group having 1, 2, 3, 4, or 5 cells, and so on.

[0021] Unless otherwise indicated herein or clearly contradicted by the context, the terms “a / an” and “the”, as well as similar pronouns, used in the context of describing the materials and methods discussed herein (particularly in the context of the following claims) should be interpreted as encompassing both the singular and plural.

[0022] The term "about" as used throughout this specification is used to describe and indicate small fluctuations. For example, the term "about" means less than or equal to ±5%, such as less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.2%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Whether explicitly stated or not, all numerical values ​​herein are modified by the term "about". Values ​​modified by the term "about" naturally include specific values. For example, "about 5.0" must include 5.0.

[0023] The different aspects of this subject matter are defined in more detail in the following paragraphs. Each aspect so defined may be combined with any one or more other aspects unless explicitly indicated otherwise. Any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0024] Throughout this specification, the phrase "in one embodiment" or "an embodiment" means that a feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the currently claimed invention. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, features, structures, or characteristics may be combined in any suitable manner as will be apparent to those skilled in the art based on this disclosure. Moreover, while some embodiments described herein include some but not others of features included in other embodiments, as will be understood by those skilled in the art, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the appended claims, any claimed embodiment may be used in any combination.

[0025] Although the embodiments disclosed herein have been described with reference to methods, it should be understood that these embodiments are merely illustrative of the principles and applications of the currently claimed invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatus of the currently claimed invention without departing from the spirit and scope of the currently claimed invention. Therefore, the currently claimed invention is intended to include modifications and variations within the scope of the appended claims and their equivalents, and the embodiments described above are presented for illustrative purposes and not for limitation. All patents and publications cited herein are incorporated by reference for their specific teachings as mentioned, unless otherwise specifically stated to be incorporated.

[0026] Unless otherwise indicated herein or otherwise clearly contradicted by the context, all methods described herein may be performed in any suitable order. Unless otherwise stated, the use of any and all embodiments or exemplary language (e.g., "such") provided herein is intended only to better illustrate the materials and methods and does not constitute a limitation on the scope.

[0027] For the purposes of the invention currently claimed, the term "polymer" refers to a single polymer or a mixture of polymers produced in a reaction in which monomers form macromolecules.

[0028] For the purposes of the invention currently claimed, "polymer emulsion" refers to an emulsion or colloidal dispersion containing water-soluble and / or water-dispersible polymers.

[0029] For the purposes of the invention currently claimed, "resin dispersion" refers to resin dispersed in water.

[0030] For the purposes of the invention currently claimed, "polymer seed" refers to a polymer that acts as a seed in polymerization.

[0031] For the purposes of the invention currently claimed, a surfactant is defined as a surface-active compound that reduces the surface tension of a liquid, the interfacial tension between two liquids, or between a liquid and a solid. The terms surfactant and emulsifier are used interchangeably herein.

[0032] For the purposes of the invention currently claimed, "water solubility" means that the relevant components or ingredients of the composition can be dissolved in the aqueous phase at the molecular level.

[0033] For the purposes of the invention currently claimed, "water dispersibility" means that the relevant components or ingredients of the composition can be dispersed in an aqueous phase and form a stable emulsion or suspension.

[0034] For the purposes of the invention currently claimed, the adhesive or solid adhesive is the non-volatile component of the polymer emulsion of the present invention, and is free of pigments and fillers.

[0035] For the purposes of the invention currently claimed, the term "carrier resin" refers to a low molecular weight copolymer (average molecular weight of about 1,500 g / mol to 35,000 g / mol) comprising styrene, acrylic acid and / or acidic monomers, which can be dispersed in water after neutralization of the acidic component.

[0036] For the purposes of the invention currently claimed, the terms “aqueous” or “water-based” as used herein refer to a large portion of water, other than organic solvents, that serves as the primary dispersion medium.

[0037] The use of (methyl) in monomers or repeating units indicates an optional methyl group. The term "copolymer" refers to copolymers including block or random copolymers that can be obtained through free radical polymerization.

[0038] For the purposes of the currently claimed invention, the term "bimodal particle size distribution" as used herein refers to two different sets of particle size distributions. For the purposes of the currently claimed invention, the term "multimodal particle size distribution" as used herein refers to more than two different sets of particle size distributions.

[0039] For the purposes of the invention currently claimed, the term "surfactant-free" means an emulsion in which polymerization is carried out without the use of surfactants and no surfactants are added to the composition before or at any time during the formation process.

[0040] For the purposes of the invention currently claimed, “theoretical glass transition temperature” or “theoretical Tg” refers to the estimated Tg of a polymer or copolymer calculated using the Fox equation. The Fox equation can be used to estimate the glass transition temperature of polymers or copolymers, as described, for example, in L. H. Perling, “Introduction to Physical Polymer Science”, 2nd ed., John Wiley & Sons, New York, p. 357 (1992) and T. Fox, Bulletin of the American Physical Society, 1, 123 (1956), both of which are incorporated herein by reference. For example, the theoretical glass transition temperature of a copolymer derived from monomers a, b, ..., i can be calculated according to the following equation, where w a T is the weight fraction of monomer a in the copolymer. ga It is the glass transition temperature of the homopolymer of monomer a, w b T is the weight fraction of monomer b in the copolymer. gb It is the glass transition temperature of the homopolymer of monomer b, w i T is the weight fraction of monomer i in the copolymer. gi T is the glass transition temperature of the homopolymer of monomer i, and T g It is the theoretical glass transition temperature of copolymers derived from monomers a, b, ... and i.

[0041]

[0042] The terms "wt.%" or "wt.%" used in this invention refer to the total weight of the composition. Furthermore, as described below, the sum of the wt.% of all compounds in each component is 100 wt.% or higher.

[0043] For the purposes of the currently claimed invention, the mass-average (Mw) and number-average (Mn) molecular weights were determined by gel permeation chromatography at 40°C using a high-performance liquid chromatography pump and a refractive index detector. Tetrahydrofuran was used as the eluent at a rate of 1 ml / min. Calibration was performed using polystyrene standards.

[0044] The above measurement techniques are well known to those skilled in the art and therefore do not limit the present invention.

[0045] "Substituted" means an organic group (e.g., alkyl) as defined below, wherein one or more bonds to the hydrogen atom contained therein are replaced by bonds to non-hydrogen or non-carbon atoms. Substituted groups also include groups in which one or more bonds to hydrogen atoms are replaced by one or more bonds to heteroatoms (including double or triple bonds). Therefore, unless otherwise specified, a substituted group will be substituted by one or more substituents. In some embodiments, the substituted group is substituted by one, two, three, four, five, or six substituents. Examples of substituents include: halogens (i.e., F, Cl, Br, and I); hydroxyl groups; alkoxy, alkenoxy, alkynoxy, aryloxy, arylalkoxy, heterocyclic alkoxy, and heterocyclic alkoxy groups; carbonyl (oxygen-containing); carboxyl groups; esters; ethers; urethanes; oximes; hydroxylamines; alkoxyamines; arylalkoxyamines; thiols; sulfides; sulfoxides; sulfones; sulfonyl groups; sulfonamides; amines; N-oxides; hydrazines; acylhydrazines; hydrazones; azides; amides; ureas; enamines; imides; isocyanates; isothiocyanates; cyanates; thiocyanates; imides; nitro groups; nitriles (i.e., CN); etc.

[0046] As used herein, "alkyl" includes straight-chain and branched alkyl groups having 1 to about 20 carbon atoms, and typically 1 to 12 carbon atoms, or in some embodiments, 1 to 8 carbon atoms. As used herein, "alkyl" includes cycloalkyl groups as defined below. Alkyl groups can be substituted or unsubstituted. Examples of straight-chain alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl. Examples of branched alkyl groups include, but are not limited to, isopropyl, sec-butyl, tert-butyl, neopentyl, and isopentyl. Representative substituted alkyl groups may be substituted once or more by, for example, amino, thio, hydroxyl, cyano, alkoxy, and / or halogen groups (such as F, Cl, Br, and I groups). As used herein, the term haloalkyl is an alkyl group having one or more halogen groups. In some embodiments, haloalkyl refers to perhaloalkyl.

[0047] The cycloalkyl group is a cyclic alkyl group, such as, but not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. In some embodiments, the cycloalkyl group has 3 to 8 ring members, while in other embodiments, the number of ring carbon atoms ranges from 3 to 5, 6, or 7. The cycloalkyl group can be substituted or unsubstituted. The cycloalkyl group further comprises polycyclic cycloalkyl groups such as, but not limited to, norbornel, adamantyl, bornel, camphenyl, isocamphenyl, and carmineyl, and fused rings such as, but not limited to, decahydronaphthyl esters. The cycloalkyl group also comprises rings substituted with straight-chain or branched alkyl groups as defined above. Representative substituted cycloalkyl groups can be monosubstituted or substituted more than once, such as, but not limited to: 2,2-; 2,3-; 2,4-; 2,5-; or 2,6-disubstituted cyclohexyl groups or mono, di, or trisubstituted norbornyl or cycloheptyl groups, which can be substituted with, for example, alkyl, alkoxy, amino, thio, hydroxyl, cyano, and / or halogen groups.

[0048] As used herein, “aryl” or “aromatic” refers to a cyclic aromatic hydrocarbon that does not contain heteroatoms. Aryl groups comprise monocyclic, bicyclic, and polycyclic ring systems. Therefore, aryl groups include, but are not limited to, phenyl, azulel, heptalenyl, biphenylenyl, indole, fluorenyl, phenanthrene, triphenylene, pyrene, naphthonaphthyl, chrysenyl, biphenyl, anthracene, indene, indanyl, cyclopentadienyl, and naphthyl. Aryl groups having one or more alkyl groups may also be referred to as alkylaryl groups. In some embodiments, the aryl group comprises 6 to 14 carbon atoms in the cyclic portion of the group, and in other embodiments, from 6 to 12 or even 6 to 10 carbon atoms. The phrase “aryl” includes groups containing fused rings such as fused aromatic-aliphatic ring systems (e.g., indene, tetrahydronaphthyl, etc.). Aryl groups can be substituted or unsubstituted.

[0049] For the purposes of the currently claimed invention, the term "(meth)acrylic acid" or "(meth)acrylate" refers to acrylic acid or methacrylic acid, esters of acrylic acid or methacrylic acid, and salts, amides, and other suitable derivatives of acrylic acid or methacrylic acid, as well as mixtures thereof. Exemplary examples of suitable (meth)acrylic acid monomers include, but are not limited to, the following methacrylates: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate (BMA), isopropyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isoamyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, 2-sulfoethyl methacrylate, trifluoroethyl methacrylate, glycidyl methacrylate (GMA), benzyl methacrylate, allymethacrylate, methylpropyl methacrylate, etc. 2-Butoxyethyl methacrylate, 2-chloroethyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl methacrylate, cinnamon methacrylate, crotonyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, furfuryl methacrylate, hexafluoroisopropyl methacrylate, methylallyl methacrylate, 3-methoxybutyl methacrylate, 2-methoxybutyl methacrylate, 2-nitro-2-methylpropyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, phenyl methacrylate, propargyl methacrylate, tetrahydrofurfuryl methacrylate, and tetrahydropyran methacrylate.Suitable examples of acrylates include, but are not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate (BA), n-decyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, isoamyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, tert-butylaminoethyl acrylate, 2-sulfoethyl acrylate, trifluoroethyl acrylate, glycidyl acrylate, benzyl acrylate, allyl acrylate, n-butoxyethyl acrylate, and acrylic acid. 2-Chloroethyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, cinnamon acrylate, croton acrylate, cyclohexyl acrylate, cyclopentyl acrylate, 2-ethoxyethyl acrylate, furfuryl acrylate, hexafluoroisopropyl acrylate, methyl allyl acrylate, 3-methoxybutyl acrylate, 2-methoxybutyl acrylate, 2-nitro-2-methylpropyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-phenoxyethyl acrylate, 2-phenylethyl acrylate, phenyl acrylate, propargyl acrylate, tetrahydrofuran acrylate, and tetrahydropyran acrylate.

[0050] For the purposes of the invention currently claimed, the term styrene refers to styrene or α-methylstyrene.

[0051] One aspect of the present invention relates to a method for preparing a polymer emulsion, the method comprising at least the following steps:

[0052] i) Provide a resin dispersion containing at least one resin in water;

[0053] ii) Adding at least one polymer seed and a polymerization mixture to a resin dispersion, said polymerization mixture comprising at least one copolymerizable monomer; and

[0054] iii) Preparation of polymer emulsions in water by free radical emulsion polymerization of polymer mixtures, resin dispersions and polymer seeds;

[0055] Based on the total weight of the polymer emulsion, the polymer emulsion has a solid content of at least 55 wt.%.

[0056] In one embodiment of the invention, the polymer emulsion further includes the step of adding at least one surfactant to the resin dispersion, wherein the amount is ≤0.10 wt.% based on the total weight of the polymer emulsion. In other exemplary embodiments, the amount of at least one surfactant added ranges from ≤0.09 wt.% or ≤0.08 wt.%, or ≤0.07 wt.%, or ≤0.06 wt.%, or ≤0.05 wt.%, or ≤0.04 wt.%, or ≤0.03 wt.%, or ≤0.02 wt.%, or ≤0.01 wt.%, or ≤0.001 wt.%.

[0057] Suitable surfactants include nonionic surfactants and anionic surfactants. Examples of nonionic surfactants include, but are not limited to, 5 to 70 moles of ethylene oxide added to straight-chain and branched alkanols having 6 to 22 carbon atoms, or corresponding C6-C22 alkylphenols, or fatty acids, or higher fatty amides, or primary and secondary higher alkylamines; block copolymers of propylene oxide and ethylene oxide, and mixtures thereof.

[0058] Representative examples of anionic surfactants include, but are not limited to, anionic compounds obtained from sulfonated fatty acid derivatives such as sulfonated tallow, sulfonated vegetable oils, and sulfonated marine animal oils. Commercially available emulsifiers in this group include TallosanRC, a sulfonated tallow sold by General Dyestuff Corp; Acidolate, a sulfonated oil sold by White Laboratories, Inc.; and Chemooil 412, a sulfonated castor oil sold by Standard Chemical Co. Also useful are various sulfonated and sulfated mono- and poly-ol fatty acid esters, such as Nopco2272R, a sulfated butyl ester of a fatty acid ester sold by Nopco Chemical Company; Nopco 1471, a sulfated vegetable oil sold by Nopco Chemical Company; Sandozol N, a sulfated fatty acid ester sold by Sandoz, Inc.; and Stantex 322, a sulfated ester sold by Standard Chemical Products, Inc. Sulfated and sulfonated fatty alcohols can also be used as emulsifiers, including anionic agents such as Duponal ME, sodium dodecyl sulfate, Duponal L142, sodium hexadecyl sulfate, Duponal LS, an oil-based sodium sulfate, sold by EIdePont de Nemoursand Co.; and Tergitol 4, a sodium sulfate derivative of 7-ethyl-2-methyl,4-undecanoyl alcohol, Tergitol 7, a sodium sulfate derivative of 3,9-diethyltridecanoyl-6, and Tergitol 08, a sodium sulfate derivative of 2-ethyl-1-hexanol, sold by Union Carbide Corp., Chemical Division. Preferred anionic surfactants are alkyl esters of alkali metal salts of sulfosuccinate.

[0059] In one embodiment of the invention, the polymer emulsion in step (iii) of the method disclosed herein is surfactant-free. For the purposes of this invention, "surfactant-free" means that, based on the total weight of the polymer emulsion, the polymer emulsion may contain at least one surfactant in an amount ≤0.10 wt.%.

[0060] In one embodiment of the invention, the method for preparing the polymer emulsion includes at least the step of providing a resin dispersion comprising at least one resin in water. In one embodiment of the invention, the at least one resin is selected from the group consisting of polyacrylate, polymethacrylate, and polystyrene.

[0061] In another embodiment of the invention, at least one resin is derived from a monomer selected from the group consisting of acrylates, styrene, and methacrylates and mixtures thereof.

[0062] Exemplary acrylate and methacrylate monomers include, but are not limited to, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isobutyl methacrylate, -hexyl methacrylate, n-heptyl methacrylate, 2-methylheptyl methacrylate, octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, -decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, glycidyl methacrylate, alkyl crotonate, vinyl acetate, and di-maleic acid. Butyl acetate, dioctyl maleate, hydroxyethyl methacrylate, allyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, 2-ethoxyethyl methacrylate, 2-methoxy methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-propylheptyl methacrylate, 2-phenoxyethyl methacrylate, isobornyl methacrylate, caprolactone methacrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol (meth)acrylate, benzyl methacrylate, hydroxypropyl methacrylate, methyl polyethylene glycol (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and combinations thereof. Other suitable monomers include acrylic acid, acrylates, and mixtures thereof.

[0063] For the purposes of the currently claimed invention, the polymer used as the base for the diluted resin dispersion can be prepared by a continuous free radical polymerization process at relatively high temperatures. Here, polymerization is carried out in a homogeneous environment. The high reaction temperature allows for the achievement of low molecular weight resins without the use of chain transfer agents. After the polymerization step, the resin is subjected to a devolver to remove unreacted monomers and process solvents. The polymer is prepared by a high-temperature, continuous polymerization process as described in U.S. Patent Nos. 5,461,60; 4,414,370; and 4,529,787, all of which are incorporated herein by reference.

[0064] In one embodiment of the invention, the amount of at least one resin present is from 5 wt.% to 40 wt.% based on the total weight of the resin dispersion. In some embodiments, in each case, the at least one resin is present in an amount ranging from ≥10 wt.%, or ≥15 wt.%, or ≥20 wt.%, or ≥25 wt.%, or ≥30 wt.%, or ≥35 wt.% based on the total weight of the resin dispersion. In some embodiments, in each case, the at least one resin is present in an amount ranging from ≤35 wt.%, or ≤30 wt.%, or ≤25 wt.%, or ≤20 wt.%, or ≤15 wt.%, or ≤10 wt.% based on the total weight of the resin dispersion. The amount of surfactant used can range from any of the aforementioned minimum values ​​to any of the aforementioned maximum values.

[0065] In one embodiment of the invention, the method for preparing a polymer emulsion includes at least the steps of providing a resin dispersion with at least one polymer seed and a polymeric mixture comprising at least one copolymerizable monomer. In one embodiment of the invention, the at least one polymer seed is selected from the group consisting of: polystyrene, poly(meth)acrylate, vinyl acetate polymer, ethylene vinyl acetate polymer, acrylic polymer, vinyl acrylate polymer, and styrene (meth)acrylate polymer. In some embodiments, the at least one polymer seed is selected from the group consisting of: polystyrene, styrene (meth)acrylate polymer, and poly(meth)acrylate.

[0066] In one embodiment of the present invention, at least one polymer seed is polystyrene.

[0067] In one embodiment of the invention, the at least one polymer seed comprises ≤1.0 wt.% of the at least one acidic monomer, based on the total weight of the at least one polymer seed. In other exemplary embodiments, in each case, based on the total weight of the polymer seed, the polymer seed contains at least one acidic monomer in an amount of ≤0.9 wt.%, or ≤0.8 wt.%, or ≤0.7 wt.%, or ≤0.6 wt.%, or ≤0.5 wt.%, or ≤0.4 wt.%, or ≤0.3 wt.%, or ≤0.2 wt.%, or ≤0.1 wt.%, or ≤0.01 wt.%.

[0068] In one embodiment of the invention, the at least one acid monomer is selected from the group consisting of: olefinically unsaturated carboxylic acids, olefinically unsaturated sulfonic acids, and vinylphosphonic acids.

[0069] In some embodiments, at least one acid monomer is selected from the group consisting of α,β-monoalkenyl unsaturated monocarboxylic acids and dicarboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, dimethacrylic acid, ethylacrylic acid, allyl acetic acid, vinyl acetic acid, vinyl lactic acid, mesonic acid, methylene malonic acid, citraconic acid, and combinations thereof. Examples of suitable olefinic unsaturated sulfonic acids include, but are not limited to, vinyl sulfonic acid, styrene sulfonic acid, acrylamide methylpropane sulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, and combinations thereof. The acid group can be partially or completely neutralized using a suitable base such as an aqueous solution of sodium hydroxide or potassium hydroxide or ammonia as a neutralizing agent.

[0070] In one embodiment of the invention currently protected, the average particle size diameter of at least one polymer seed is between 10 nm and 50 nm, determined by a dynamic light scattering method. In some embodiments, the number-average particle size of at least one polymer seed is ≥10 nm, for example ≥15 nm, or ≥20 nm, or ≥25 nm, or ≥30 nm, or ≥35 nm, or ≥40 nm, or ≥45 nm, each determined by a dynamic light scattering method. In some embodiments, the number-average particle size of at least one polymer seed is in the range ≤50 nm, for example ≤45 nm, or ≤40 nm, or ≤35 nm, or ≤30 nm, or ≤25 nm, or ≤20 nm, or ≤15 nm, each determined by a dynamic light scattering method. The number-average particle size diameter of at least one polymer can be within the range of any of the aforementioned minimum to any of the aforementioned maximum values.

[0071] In one embodiment of the invention, the at least one polymer seed has a weight-average molecular weight in the range of 10,000 g / mol to 500,000 g / mol, as determined by gel permeation chromatography. In some exemplary embodiments, the weight-average molecular weight of the at least one polymer seed is ≥20,000 g / mol, or ≥30,000 g / mol, or ≥40,000 g / mol, or ≥50,000 g / mol, or ≥60,000 g / mol, or ≥70,000 g / mol, or ≥80,000 g / mol, or ≥90,000 g / mol, or ≥100,000 g / mol, or ≥150,000 g / mol, or ≥200,000 g / mol, or ≥250,000 g / mol, or ≥300,000 g / mol, or ≥400,000 g / mol, each determined by gel permeation chromatography. In some exemplary embodiments, the weight-average molecular weight of at least one polymer seed is ≤450,000 g / mol, or ≤400,000 g / mol, or ≤300,000 g / mol, or ≤200,000 g / mol, or ≤100,000 g / mol, or ≤80,000 g / mol, or ≤60,000 g / mol, or ≤40,000 g / mol, or ≤20,000 g / mol, each determined by gel permeation chromatography. The average molecular weight of at least one polymer seed can range from any of the above minimum values ​​to any of the above maximum values.

[0072] In one embodiment of the invention, the content of at least one polymer seed varies from 0.1 wt.% to 5.0 wt.% based on the total weight of the polymer emulsion. In some exemplary embodiments, in each case, the content of at least one polymer seed is ≥0.2 wt.%, or ≥0.3 wt.%, or ≥0.4 wt.%, or ≥0.5 wt.%, or ≥0.6 wt.%, or ≥0.7 wt.%, or ≥0.8 wt.%, or ≥0.9 wt.%, or ≥1.0 wt.%, or ≥1.5 wt.%, or ≥2.0 wt.%, or ≥2.5 wt.%, or ≥3.0 wt.%, or ≥3.5 wt.%, or ≥4.0 wt.%, based on the total weight of the polymer emulsion. In some exemplary embodiments, in each case, based on the total weight of the polymer emulsion, the content of at least one polymer seed is ≤4.5 wt.%, or ≤4.0 wt.%, or ≤3.5 wt.%, or ≤3.0 wt.%, or ≤2.5 wt.%, or ≤2.0 wt.%, or ≤1.0 wt.%, or ≤0.5 wt.%. The number of polymer seeds in the polymer emulsion can range from any of the above minimum values ​​to any of the above maximum values.

[0073] In one embodiment of the currently claimed invention, the solid content of at least one polymer seed is in the range of 1.0 wt.% to 50.0 wt.% based on the total weight of the polymer seeds. In some exemplary embodiments, in each case, the solid content of the at least one polymer seed is in the range of ≥2.0 wt.%, or ≥3.0 wt.%, or ≥4.0 wt.%, or ≥5.0 wt.%, or ≥6.0 wt.%, or ≥7.0 wt.%, or ≥8.0 wt.%, or ≥9.0 wt.%, or ≥10.0 wt.%, or ≥15.0 wt.%, or ≥20.0 wt.%, or ≥25.0 wt.%, or ≥30.0 ​​wt.%, or ≥35.0 wt.%, or ≥40.0 wt.% based on the total weight of the polymer seeds. In some exemplary embodiments, in each case, based on the total weight of the polymer seeds, the solid content of the at least one polymer seed is in the range of ≤45.0 wt.%, or ≤40.0 wt.%, or ≤35.0 wt.%, or ≤30.0 wt.%, or ≤25.0 wt.%, or ≤20.0 wt.%, or ≤15.0 wt.%, or ≤10.0 wt.%, or ≤5.0 wt.%, or ≤4.0 wt.%, or ≤3.0 wt.%, or ≤2.0 wt.%. Based on the total weight of the polymer seeds, the solid content in the at least one polymer seed can be in the range of any of the above minimum to any of the above maximum values.

[0074] In one embodiment of the invention, the at least one copolymerizable monomer is selected from the group consisting of: acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl acetic acid, vinyl lactic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamide methylpropane sulfonic acid, sulfonyl acrylate, sulfonyl methacrylate, styrene, α-methylstyrene, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 1,4-butanediol diacrylate, n-butyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate. Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isoamyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl methacrylate, cyclohexyl methacrylate, cinnamon methacrylate, glycidyl methacrylate, crotonyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, ureomethacrylate, acrylamide, methacrylamide, N-butoxymethyl methacrylamide, N-hydroxymethyl acrylamide, N-hydroxymethyl methacrylamide, diacetone acrylamide, vinyl acetate, and acrylonitrile.

[0075] In some exemplary embodiments, at least one copolymerizable monomer is selected from the group consisting of acrylates and methacrylates. Exemplary acrylate and methacrylate monomers include, but are not limited to, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, 2-methylheptyl methacrylate, octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, glycidyl methacrylate, alkyl crotonate, vinyl acetate, and butyl di-n-maleate. Dioctyl maleate, hydroxyethyl (meth)acrylate, allyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxy (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-propylheptyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, caprolactone (meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol (meth)acrylate, benzyl (meth)acrylate, hydroxypropyl (meth)acrylate, methyl polyethylene glycol (meth)acrylate, 3,4-epoxycyclohexyl meth (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and combinations thereof.

[0076] In one embodiment of the invention, the theoretical weight-average molecular weight of the at least one copolymerizable monomer is from 50 g / mol to 500 g / mol. In some exemplary embodiments, the theoretical weight-average molecular weight of the at least one copolymerizable monomer is ≥70 g / mol, or ≥90 g / mol, or ≥100 g / mol, or ≥120 g / mol, or ≥150 g / mol, or ≥175 g / mol, or ≥190 g / mol, or ≥200 g / mol, or ≥220 g / mol, or ≥250 g / mol, or ≥275 g / mol, or ≥300 g / mol, or ≥350 g / mol, or ≥400 g / mol, or ≥450 g / mol. In some exemplary embodiments, the theoretical weight-average molecular weight of at least one comonomer is ≤450 g / mol, or ≤400 g / mol, or ≤350 g / mol, or ≤300 g / mol, or ≤250 g / mol, or ≤200 g / mol, or ≤100 g / mol, or ≤75 g / mol. The theoretical weight-average molecular weight of at least one comonomer can range from any of the above minimum values ​​to any of the above maximum values.

[0077] In one embodiment of the invention, at least one copolymerizable monomer is present in an amount ranging from 15 wt.% to 65 wt.% based on the total weight of the polymer emulsion. In some exemplary embodiments, in each case, at least one copolymerizable monomer is present in an amount ranging from ≥20 wt.%, or ≥25 wt.%, or ≥30 wt.%, or ≥35 wt.%, or ≥40 wt.%, or ≥45 wt.%, or ≥50 wt.%, or ≥55 wt.%, or ≥60 wt.% based on the total weight of the polymer emulsion. In some exemplary embodiments, in each case, at least one copolymerizable monomer is present in an amount ranging from ≤60 wt.%, or ≤55 wt.%, or ≤50 wt.%, or ≤45 wt.%, or ≤40 wt.%, or ≤35 wt.%, or ≤30 wt.%, or ≤25 wt.%, or ≤20 wt.% based on the total weight of the polymer emulsion. The amount of at least one copolymerizable monomer can range from any of the aforementioned minimum values ​​to any of the aforementioned maximum values.

[0078] In some exemplary embodiments, at least one copolymerizable monomer is derived from at least 80 wt.% of a (meth)acrylate monomer. Suitable examples of (meth)acrylate monomers include, but are not limited to, (meth)acrylate C1-C 20 Alkyl esters, such as methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and 2-propylheptyl acrylate. Mixtures of (meth)acrylate alkyl esters are also suitable.

[0079] For the purposes of the invention currently claimed, at least one copolymerizable monomer may also be selected from acid monomers, vinyl carboxylate, vinyl aromatics, olefinic unsaturated nitrile, halogenated vinyl ethers, aliphatic hydrocarbons, and mixtures thereof.

[0080] In one embodiment of the invention, at least one copolymerizable monomer used in the polymer disclosed herein comprises less than 5 wt.% of an acid group by weight of the total monomer, for example, less than 4 wt.%, or less than 3 wt.%, or less than 2 wt.%, or less than 1 wt.%. In some embodiments, at least one copolymerizable monomer used in the polymer disclosed herein does not have an acid group.

[0081] In one embodiment of the invention, the theoretical glass transition temperature (Tg) of the at least one copolymerizable monomer is from -60°C to 10°C. In some exemplary embodiments, the theoretical glass transition temperature (Tg) of the at least one copolymerizable monomer is in the range of ≥-50°C, or ≥-40°C, or ≥-30°C, or ≥-20°C, or ≥-10°C, or ≥0°C. In some exemplary embodiments, the at least one copolymerizable monomer has a theoretical glass transition temperature (Tg) in the range of ≤5°C, or ≤0°C, or ≤-10°C, or ≤-20°C, or ≤-30°C, or ≤-40°C, or ≤-50°C. The range of the theoretical glass transition temperature of the at least one copolymerizable monomer can be any of the above minimum values ​​to any of the above maximum values.

[0082] In one embodiment of the invention, the polymerization mixture further comprises at least one water-soluble initiator.

[0083] In one embodiment of the invention, at least one water-soluble initiator is selected from the group consisting of sulfuric acid peroxide and ammonium or alkali metal salts of peroxides.

[0084] In one embodiment of the invention, the at least one water-soluble initiator is selected from the group consisting of: ammonium or alkali metal salts of persulfate, such as sodium persulfate, hydrogen peroxide, or organic peroxides, such as tert-butyl hydroperoxide. Also suitable as initiators are known reduction-oxidation (redox) initiators. A redox initiator system consists of at least one, typically inorganic, reducing agent and an organic or inorganic oxidizing agent. The oxidizing component includes, for example, initiators for emulsion polymerization as described above. The reducing component is, for example, an alkali metal salt of sulfurous acid, such as sodium sulfite, sodium bisulfite, an alkali metal salt of disulfite, such as sodium bisulfite, an addition compound of bisulfite with aliphatic aldehydes and ketones, such as acetone bisulfite, or a reducing agent, such as hydroxymethanesulfinic acid and its salts, or ascorbic acid. Redox initiator systems can be used with soluble metal compounds whose metal components can exist in multiple valence states. Commonly used redox initiator systems include, for example, ascorbic acid / ferrous sulfate / sodium persulfate, tert-butyl hydroperoxide / sodium metabisulfite, and tert-butyl hydroperoxide / sodium hydroxymethyl sulfinate. Individual components, such as reducing components, can also be mixtures, such as a mixture of sodium hydroxymethyl sulfinate and sodium metabisulfite.

[0085] In one embodiment of the invention, the amount of at least one water-soluble initiator is from 0.10 wt.% to 5.0 wt.% based on the total weight of monomers in the polymerization mixture. In some exemplary embodiments, in each case, the content of at least one water-soluble initiator is ≥0.20 wt.%, or ≥0.30 wt.%, or ≥0.40 wt.%, or ≥0.50 wt.%, or ≥0.60 wt.%, or ≥0.70 wt.%, or ≥0.80 wt.%, or ≥0.90 wt.%, or ≥1.0 wt.%, or ≥1.5 wt.%, or ≥2.0 wt.%, or ≥2.5 wt.%, or ≥3.0 wt.%, or ≥3.5 wt.%, or ≥4.0 wt.%, or ≥4.5 wt.%, based on the total weight of monomers in the polymerization mixture. In some exemplary embodiments, in each case, based on the total weight of the monomers in the polymerization mixture, the content of at least one water-soluble initiator is ≤4.5 wt.%, or ≤4.0 wt.%, or ≤3.5 wt.%, or ≤3.0 wt.%, or ≤2.5 wt.%, or ≤2.0 wt.%, or ≤1.5 wt.%, or ≤1.0 wt.%, or ≤0.5 wt.%, or ≤0.3 wt.%. The amount of at least one water-soluble initiator can be any of the above minimum to any of the above maximum values.

[0086] In one embodiment of the present invention, the weight ratio of the at least one polymer seed to the at least one copolymerizable monomer is in the range of 0.2:100 to 5:100. In some exemplary embodiments of the present invention, the weight ratio of the at least one polymer seed to the at least one copolymerizable monomer is in the range of 0.2:100 to 0.4:100, or 0.2:100 to 0.5:100, or 0.2:100 to 1.0:100, or 0.2:100 to 2.0:100, or 0.2:100 to 3.0:100, or 0.2:100 to 4.0:100. In some exemplary embodiments of the present invention, the weight ratio of the at least one polymer seed to the at least one copolymerizable monomer is less than 4:100, less than 3:100, less than 2:100, less than 1:100, less than 0.5:100, or less than 0.3:100. In some exemplary embodiments of the present invention, the weight ratio of at least one polymer seed to at least one copolymerizable monomer is at least 0.3:100, at least 0.5:100, at least 1.0:100, at least 1.5:100, at least 2.0:100, at least 2.5:100, at least 3.0:100, at least 3.5:100, at least 4.0:100, or at least 4.5:100. The weight ratio of at least one polymer seed to at least one copolymerizable monomer can be within the range of any of the above minimum ratios to any of the above maximum ratios.

[0087] In one embodiment of the invention, the weight ratio of the at least one resin to the at least one copolymerizable monomer is in the range of 5:100 to 40:100. In some exemplary embodiments, the weight ratio of the at least one resin to the at least one copolymerizable monomer is 10:100 to 40:100, or 15:100 to 20:100, or 5:100 to 40:100, or 5:100 to 35:100, or 5:100 to 30:100, or 5:100 to 20:100. In some exemplary embodiments of the invention, the weight ratio of the at least one resin to the at least one copolymerizable monomer is less than 35:100, less than 30:100, less than 25:100, less than 20:100, less than 15:100, or less than 10:100. In some exemplary embodiments of the currently claimed invention, the weight ratio of at least one resin to at least one copolymerizable monomer is at least 10:100, at least 15:100, at least 20:100, at least 25:100, at least 30:100, or at least 35:100. The weight ratio of at least one resin to at least one copolymerizable monomer can be within the range of any of the minimum to any of the maximum ratios described above.

[0088] In one embodiment of the invention, the solid content of the polymer emulsion is at least 60 wt.% based on the total weight of the polymer emulsion. In some exemplary embodiments, the solid content of the polymer emulsion is at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, at least 80 wt.%, or at least 85 wt.%.

[0089] In one embodiment of the invention, the glass transition temperature (Tg) of the polymer emulsion is determined to be from -60°C to 120°C using dynamic scanning calorimetry. In some embodiments, the glass transition temperature (Tg) of the polymer emulsion is determined by dynamic scanning calorimetry in each case to be ≥-50°C, or ≥-40°C, or ≥-30°C, or ≥-20°C, or ≥-10°C, or ≥0°C, or ≥5°C, or ≥10°C, or ≥20°C, or ≥30°C, or ≥40°C, or ≥50°C, or ≥60°C, or ≥70°C, or ≥80°C, or ≥90°C, or ≥100°C. In some exemplary embodiments, the glass transition temperature range of the polymer emulsion, determined by dynamic scanning calorimetry in each case, is ≤110°C, or ≤100°C, or ≤90°C, or ≤80°C, or ≤70°C, or ≤60°C, or ≤50°C, or ≤40°C, or ≤30°C, or ≤20°C, or ≤10°C, or ≤0°C, or ≤-10°C, or ≤-20°C, or ≤-30°C, or ≤-40°C, or ≤-50°C. The measured glass transition temperature of the polymer emulsion can be within any of the above minimum values ​​to any of the above maximum values.

[0090] In one embodiment of the currently claimed invention, the viscosity of the polymer emulsion is measured at 60 RPM at 25°C using a viscometer with a No. 63 rotor, and the viscosity is in the range of 50 cps to 10,000 cps. In some exemplary embodiments, the viscosity range of the polymer emulsion, measured at 60 RPM at 25°C using a viscometer with a No. 63 rotor in each case, is ≥100 cps, or ≥200 cps, or ≥300 cps, or ≥400 cps, or ≥500 cps, or ≥600 cps, or ≥700 cps, or ≥800 cps, or ≥900 cps, or ≥1000 cps, or ≥1500 cps, or ≥2000 cps, or ≥3000 cps, or ≥4000 cps, or ≥5000 cps, or ≥6000 cps, or ≥7000 cps, or ≥8000 cps, or ≥9000 cps. In some exemplary embodiments, in each case, a viscometer with a No. 63 rotor is used to measure the viscosity of the polymer emulsion at 25°C at 60 RPM. The viscosity range of the polymer emulsion is ≤9,000 cps, or ≤8,000 cps, or ≤7,000 cps, or ≤6,000 cps, or ≤5,000 cps, or ≤4,000 cps, or ≤3,000 cps, or ≤2,000 cps, or ≤1,000 cps, or ≤500 cps, or ≤200 cps. The viscosity of the polymer emulsion can be within any of the above minimum values ​​to any of the above maximum values.

[0091] In one embodiment of the invention, the polymer emulsion comprises particles with a volume average particle size in the range of 100 nm to 1000 nm, as determined by dynamic light scattering. In some exemplary embodiments, in each case, the polymer emulsion comprises particles with a volume average particle size ≥150 nm, or ≥200 nm, or ≥250 nm, or ≥300 nm, or ≥350 nm, or ≥400 nm, or ≥450 nm, or ≥500 nm, or ≥550 nm, or ≥600 nm, or ≥650 nm, or ≥700 nm, or ≥750 nm, or ≥800 nm, or ≥850 nm, or ≥900 nm, or ≥950 nm, as determined by dynamic light scattering. In some exemplary embodiments, in each case, the polymer emulsion comprises particles with a volume average particle size ≤950 nm, or ≤900 nm, or ≤800 nm, or ≤850 nm, or ≤800 nm, or ≤750 nm, or ≤700 nm, or ≤650 nm, or ≤600 nm, or ≤550 nm, or ≤500 nm, or ≤450 nm, or ≤400 nm, or ≤350 nm, or ≤300 nm, or ≤250 nm, or ≤200 nm, or ≤150 nm, as determined by dynamic light scattering. The range of the volume average particle size in the polymer emulsion can be from any of the aforementioned minimum values ​​to any of the aforementioned maximum values.

[0092] In one embodiment of the present invention, the method for preparing a polymer emulsion includes at least the step of preparing a polymer emulsion in water by free radical emulsion polymerization of a polymerization mixture, a resin dispersion, and polymer seeds. In one embodiment of the present invention, the free radical emulsion polymerization is a semi-batch process.

[0093] In one embodiment of the invention, the particle size distribution of the particles in the polymer emulsion is bimodal or multimodal. In the case of bimodal and multimodal distributions, the average particle size distribution of the particles dispersed in the polymer emulsion can be as high as 1000 nm. Average particle size refers to the particle size distribution d... 50 The particle diameter ratio d (i.e., 50 wt.% of the total weight of all particles) 50 Small. Analytical ultracentrifuges can be used to determine particle size distribution.

[0094] The preparation process of the polymer emulsion includes the polymerization of the reaction mixture of the components described in step (iii) disclosed herein. Polymerization is typically carried out via a free radical emulsion polymerization process. Emulsion polymerization can be performed by varying the monomer feed rate. Emulsion polymerization can be carried out under surfactant-free conditions. The emulsion polymerization temperature can be from 10°C to 130°C, for example, from 50°C to 100°C. The temperature can be increased during polymerization, for example, from an initial temperature in the range of 50°C to 85°C to a final temperature in the range of 85°C to 100°C. The polymerization medium can contain only water or a mixture of water-miscible liquids, such as methanol, ethanol, or tetrahydrofuran. In some embodiments, the polymerization medium contains no organic solvent and only water.

[0095] Emulsion polymerization can be carried out batch or semi-batch. In some embodiments, a portion of the monomer can be heated to the polymerization temperature and partially polymerized, followed by continuous, gradual, or cumulative concentration gradient feeding of the remaining portion of the polymerization batch into the polymerization zone. In some embodiments, a method for preparing a polymer emulsion includes polymerizing at least one olefinically unsaturated monomer in a first emulsion polymerization step to produce a first polymer having a first theoretical glass transition temperature Tg; and polymerizing one or more olefinically unsaturated monomers in a second emulsion polymerization step to produce a second polymer having a second theoretical glass transition temperature Tg, wherein the one or more olefinically unsaturated monomers account for at least 50% by weight of the monomers polymerized to form the second polymer particles. In some embodiments, the first polymerization step and / or the second polymerization step is carried out at a first polymerization temperature in the range of 10°C to 130°C (e.g., 50°C to 100°C, or 70°C to 90°C). In one embodiment, the first and second polymerization steps are carried out at a polymerization temperature less than or equal to 85°C.

[0096] Emulsion polymerization can be carried out using a variety of auxiliaries, including water-soluble initiators and modifiers. Examples of water-soluble initiators used for emulsion polymerization are ammonium salts and alkali metal salts of disulfite, such as sodium disulfite, hydrogen peroxide, or organic peroxides, such as tert-butyl hydroperoxide. Reduction-oxidation (redox) initiator systems are also suitable as initiators for emulsion polymerization. Redox initiator systems consist of at least one, and typically inorganic, reducing agent and an organic or inorganic oxidizing agent. For example, the oxidizing component includes the initiators already specified above for emulsion polymerization. For example, the reducing component is an alkali metal salt of sulfurous acid (such as sodium sulfite, sodium bisulfite), an alkali metal salt of disulfite (such as sodium bisulfite), a bisulfite addition compound having aliphatic aldehydes and ketones (such as acetone bisulfite), or a reducing agent (such as hydroxymethyl sulfinic acid and its salts) or ascorbic acid. Redox initiator systems can be used with soluble metal compounds, whose metal components can exist in multiple valence states. For example, typical redox initiator systems include ascorbic acid / ferrous sulfate / sodium persulfate, tert-butyl hydroperoxide / sodium metabisulfite, tert-butyl hydroperoxide / sodium hydroxymethanesulfinate, or tert-butyl hydroperoxide / ascorbic acid. Individual components, such as reducing components, may also exist in mixtures, such as a mixture of sodium hydroxymethanesulfinate and sodium metabisulfite. The compounds are typically present in aqueous solutions, with lower concentrations determined by the acceptable amount of water in the dispersion and higher concentrations by the solubility of the respective compound in water. Based on the solution, the concentration can be from 0.1 wt% to 30 wt%, 0.5 wt% to 20 wt%, or 1.0 wt% to 10 wt%. Based on the monomer to be polymerized, the amount of initiator is typically from 0.1 wt% to 10 wt% or 0.5 wt% to 5 wt%. Two or more different initiators can also be used in emulsion polymerization. To remove residual monomers, the initiator can be added after the emulsion polymerization is complete.

[0097] In polymerization, molecular weight regulators or chain transfer agents can be used, for example, in amounts of 0 to 0.8 parts by weight based on 100 parts by weight of the monomer to be polymerized, to reduce the molecular weight of the copolymer. Suitable embodiments include compounds having thiol groups, such as tert-butylthiol, ethyl methacrylate of mercaptoacetate, mercaptoethanol, mercaptopropyltrimethoxysilane, and tert-dodecylthiol. Alternatively, regulators without thiol groups, such as terpinene, can be used. In some embodiments, the emulsion polymer is prepared in the presence of at least one molecular weight regulator in amounts greater than 0.5% by weight based on the monomer content. In some embodiments, the emulsion polymer is prepared in the presence of less than 0.3% by weight or less than 0.2% by weight (e.g., 0.10% by weight to 0.15% by weight) of a molecular weight regulator.

[0098] Another aspect of the invention relates to polymer emulsions obtainable by the methods disclosed herein. In one embodiment of the invention, the particle size distribution of the polymer emulsion is bimodal or multimodal. In the case of bimodal and multimodal distributions, the average particle size distribution of the particles dispersed in the polymer emulsion can be as high as 1000 nm. Average particle size refers to the d-axis of the particle size distribution. 50 (i.e., 50 wt.% of the total weight of all particles) has less than d 50 The particle size distribution can be determined using an analytical ultracentrifuge.

[0099] In another embodiment of the invention, the polymer emulsion contains at least one surfactant in an amount ranging from ≤0.10 wt.% based on the total weight of the polymer emulsion.

[0100] Suitable surfactants include nonionic surfactants and anionic surfactants. Examples of nonionic surfactants include, but are not limited to, 5 to 70 moles of ethylene oxide added to straight-chain and branched alkanols having 6 to 22 carbon atoms, or corresponding C6-C22 alkylphenols, or fatty acids, or higher fatty amides, or primary and secondary higher alkylamines; block copolymers of propylene oxide and ethylene oxide, and mixtures thereof.

[0101] Representative examples of anionic surfactants include, but are not limited to, anionic compounds obtained from sulfonated fatty acid derivatives such as sulfonated tallow, sulfonated vegetable oils, and sulfonated marine animal oils. Commercially available emulsifiers in this group include TallosanRC, a sulfonated tallow marketed by General Dyestuff Corp; Acidolate, a sulfonated oil marketed by White Laboratories, Inc.; and Chemooil 412, a sulfonated castor oil marketed by Standard Chemical Co. Also useful are various sulfonated and sulfated mono- and poly-ol fatty acid esters, such as Nopco 2272R, a sulfated butyl ester of a fatty acid ester sold by Nopco Chemical Company; Nopco 1471, a sulfated vegetable oil sold by Nopco Chemical Company; Sandozol N, a sulfated fatty acid ester sold by Sandoz, Inc.; and Stantex 322, a sulfated ester sold by Standard Chemical Products, Inc. Sulfated and sulfonated fatty alcohols can also be used as emulsifiers, including anionic agents such as Duponal ME, sodium dodecyl sulfate, Duponal L142, sodium hexadecyl sulfate, Duponal LS, an oil-based sodium sulfate, marketed by DuPont de Nemours and Co.; and Tergitol 4, a sodium sulfate derivative of 7-ethyl-2-methyl,4-undecanoyl alcohol, Tergitol 7, a sodium sulfate derivative of 3,9-diethyltridecanoyl-6, and Tergitol 08, a 2-ethyl-1-hexanol sodium sulfate derivative, marketed by Union Carbide Corp., Chemical Division. Preferred anionic surfactants are alkyl esters of alkali metal salts of sulfosuccinate.

[0102] In one embodiment of the currently claimed invention, the polymer emulsion is free of surfactants.

[0103] In another embodiment of the claimed invention, the polymer emulsion is suitable for preparing adhesives, labels, composite films, protective film laminates, coatings, sound insulations, primers, inks, and pigment dispersants. In one embodiment of the claimed invention, the polymer emulsion is used to produce adhesives. In yet another embodiment of the claimed invention, the polymer emulsion is used to produce pressure-sensitive adhesives or laminating adhesives.

[0104] In another embodiment of the currently claimed invention, the polymer emulsion may also contain dispersants, thickeners, light stabilizers, film-forming aids, defoamers, thickeners, wetting agents, biocides, viscous agents, or combinations thereof.

[0105] Examples of suitable dispersants include, but are not limited to, polyacid dispersants and hydrophobic copolymer dispersants. Polyacid dispersants are typically polycarboxylic acids, such as polyacrylic acid or polymethacrylic acid, which are present in part or in whole as their ammonium salt, alkali metal salt, alkaline earth metal salt, ammonium salt, or lower alkyl quaternary ammonium salt. Hydrophobic copolymer dispersants include copolymers of acrylic acid, methacrylic acid, or maleic acid with hydrophobic monomers.

[0106] Examples of suitable thickeners include, but are not limited to, hydrophobically modified ethylene oxide urethane (HEUR) polymers, hydrophobically modified alkali-soluble emulsion (HASE) polymers, hydrophobically modified hydroxyethyl cellulose (HMHEC), hydrophobically modified polyacrylamide, and combinations thereof. HEUR polymers are linear reaction products of diisocyanates and hydrophobically hydrocarbon-terminated polyethylene oxides. HASE polymers are homopolymers of (meth)acrylic acid, or copolymers of (meth)acrylic acid, (meth)acrylates, or maleic acid modified with hydrophobically modified vinyl monomers. HMHEC comprises hydroxyethyl cellulose modified with hydrophobically modified alkyl chains. Hydrophobically modified polyacrylamide comprises a copolymer of acrylamide and acrylamide modified with hydrophobically modified alkyl chains (N-alkylacrylamide).

[0107] Suitable defoamers include, but are not limited to, silicone oil defoamers, such as polysiloxanes, polydimethylsiloxanes, polyether-modified polysiloxanes, and combinations thereof. Exemplary siloxane defoamers include... -035, available from BYK USA Inc. Wallingford, Conn. A range of defoamers are available from Evonik Industries (Hopewell, Va.), and A range of defoamers are available from Ashland Inc. (Covington, Kentucky).

[0108] Exemplary biocides comprise 2-[(hydroxymethyl)amino]ethanol, 2-[(hydroxymethyl)amino]2-methyl-1-propanol, o-phenylphenol, sodium salt, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one (MIT), 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone, and acceptable salts thereof and combinations thereof. Examples of fungicides comprise 2-(thiocyanomethylthio)benzothiazole, 3-iodo-2-propynyl butyl carbamate, 2,4,5,6-tetrachloroisophthalonitrile, 2-(4-thiazolyl)benzimidazole, 2-n-octyl-4-isothiazolin-3-one, diiodomethyl-p-tolyl sulfone, and acceptable salts thereof and combinations thereof.

[0109] All publications, patent applications, published patents, and other documents mentioned in this specification are incorporated herein by reference as if each individual publication, patent application, published patent, or other document were specifically and individually indicated as incorporated herein by reference in its entirety. Where a definition contained in the text incorporated by reference contradicts a definition in this disclosure, the definition contained in the text incorporated by reference shall be excluded.

[0110] Implementation

[0111] The following list of embodiments is provided to further illustrate this disclosure, but it is not intended to limit this disclosure to the specific embodiments listed below.

[0112] Implementation Method 1: A method for preparing a polymer emulsion, comprising the following steps:

[0113] i) Providing a resin dispersion containing at least one resin in water;

[0114] ii) Add at least one polymer seed and a polymerization mixture to the resin dispersion, said polymerization mixture comprising at least one copolymerizable monomer; and

[0115] iii) Preparation of polymer emulsions in water by free radical emulsion polymerization of polymer mixtures, resin dispersions and polymer seeds;

[0116] Based on the total weight of the polymer emulsion, the polymer emulsion has a solid content of at least 55 wt.%.

[0117] Embodiment 2; According to the method of Embodiment 1, the polymer emulsion further includes at least one surfactant in an amount ≤0.10 wt.% based on the total weight of the polymer emulsion.

[0118] Embodiment 3: The method according to Embodiment 1 or 2, wherein the at least one resin is selected from the group consisting of: polyacrylate, polymethacrylate and polystyrene.

[0119] Embodiment 4: The method according to any one of Embodiments 1 to 3, wherein the at least one resin is present in an amount of 5 wt.% to 40 wt.% based on the total weight of the resin dispersion.

[0120] Embodiment 5: According to the method of Embodiment 1, wherein the at least one polymer seed is selected from the group consisting of: polystyrene, poly(meth)acrylate, vinyl acetate polymer, ethylene vinyl acetate polymer, acrylic polymer, vinyl acrylic polymer and styrene(meth)acrylate polymer.

[0121] Embodiment 6: According to the method of Embodiment 1, wherein, based on the total weight of the at least one polymer seed, the at least one polymer seed contains ≤1.0 wt.% of at least one acid monomer.

[0122] Embodiment 7: According to the method of Embodiment 6, wherein the at least one acid monomer is selected from the group consisting of: olefinic unsaturated carboxylic acids, olefinic unsaturated sulfonic acids, and vinylphosphonic acids.

[0123] Embodiment 8: The method according to any one of Embodiments 1 to 7, wherein the at least one polymer seed has a number-average particle size in the range of 10 nm to 50 nm as determined by dynamic light scattering.

[0124] Embodiment 9: The method according to any one of Embodiments 1 to 8, wherein the at least one polymer seed has a weight-average molecular weight in the range of 10,000 g / mol to 500,000 g / mol as determined by gel permeation chromatography.

[0125] Embodiment 10: The method according to any one of Embodiments 1 to 9, wherein the at least one polymer seed is present in an amount of 0.1 wt.% to 5.0 wt.% based on the total weight of the polymer emulsion.

[0126] Embodiment 11: The method according to any one of Embodiments 1 to 10, wherein, based on the total weight of the polymer seeds, the at least one polymer seed has a solid content in the range of 1.0 wt.% to 50.0 wt.%.

[0127] Embodiment 12: The method according to any one of Embodiments 1 to 11, wherein the at least one copolymerizable monomer is selected from the group consisting of: acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl acetic acid, vinyl lactic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamide methylpropane sulfonic acid, sulfonyl acrylate, sulfonyl methacrylate, styrene, α-methylstyrene, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 1,4-butanediol diacrylate, n-butyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate. Hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isoamyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamon methacrylate, glycidyl methacrylate, butenyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, ureomethacrylate, acrylamide, methacrylamide, N-butoxymethylmethacrylamide, N-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide, diacetone acrylamide, vinyl acetate, and acrylonitrile.

[0128] Embodiment 13: The method according to any one of Embodiments 1 to 12, wherein the at least one copolymerizable monomer has a theoretical weight-average molecular weight in the range of 50 g / mol to 500 g / mol.

[0129] Embodiment 14: The method according to Embodiment 12 or 13, wherein the at least one copolymerizable monomer is present in an amount of 15 wt.% to 65 wt.% based on the total weight of the polymer emulsion.

[0130] Embodiment 15: The method according to any one of Embodiments 1 to 14, wherein the polymerization mixture further comprises at least one water-soluble initiator.

[0131] Embodiment 16: According to the method of Embodiment 15, the at least one water-soluble initiator is selected from the group consisting of: sulfuric acid peroxide and ammonium or alkali metal salts of peroxides.

[0132] Embodiment 17: The method according to Embodiment 15 or 16, wherein the at least one water-soluble initiator is present in an amount ranging from 0.10 wt.% to 5.0 wt.% based on the total weight of the monomers in the polymerization mixture.

[0133] Embodiment 18: According to the method of Embodiment 1, the weight ratio of the at least one polymer seed to the at least one copolymerizable monomer is in the range of 0.2:100 to 5:100.

[0134] Embodiment 19: According to the method of Embodiment 1, the weight ratio of the at least one resin to the at least one copolymerizable monomer is in the range of 5:100 to 40:100.

[0135] Embodiment 20: The method according to any one of Embodiments 1 to 19, wherein the polymer emulsion has a solid content of at least 60 wt.% based on the total weight of the polymer emulsion.

[0136] Embodiment 21: The method according to any one of Embodiments 1 to 20, wherein the glass transition temperature range of the polymer emulsion is -60°C to 120°C, as determined by dynamic scanning calorimetry.

[0137] Embodiment 22: The method according to any one of Embodiments 1 to 21, wherein the viscosity of the polymer emulsion is measured at 60 RPM at 25°C using a viscometer with a rotor of No. 63, and the viscosity is in the range of 50 cps to 10,000 cps.

[0138] Embodiment 23: The method according to any one of Embodiments 1 to 22, wherein the polymer emulsion comprises particles with a volume average particle size in the range of 100 nm to 1000 nm as determined by dynamic light scattering.

[0139] Embodiment 24: The method according to any one of Embodiments 1 to 23, wherein the step of preparing the polymer emulsion in water by free radical emulsion polymerization is a semi-batch method.

[0140] Embodiment 25: A polymer emulsion that can be obtained by any one of Embodiments 1 to 25.

[0141] Embodiment 26: The polymer emulsion according to Embodiment 25 contains particles that exist in a bimodal or multimodal particle size distribution.

[0142] Embodiment 27: The polymer emulsion according to Embodiment 25 or 26, wherein the polymer emulsion contains at least one surfactant in an amount in the range of 0.10 wt.% based on the total weight of the polymer emulsion.

[0143] Embodiment 28: A polymer emulsion according to any one of Embodiments 25 to 27, wherein the polymer emulsion is suitable for preparing adhesives, composite films, protective film laminates, coatings, sound insulations, primers, inks or pigment dispersions.

[0144] Although the invention currently claimed has been described according to specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the invention currently claimed.

[0145] The invention currently claimed is associated with at least one of the following advantages:

[0146] (i) The invention currently claimed provides a polymer emulsion with a high solids content of at least 55 wt.%.

[0147] (ii) The method for preparing polymer emulsions disclosed herein eliminates the need for surfactants to stabilize polymer emulsions.

[0148] (iii) The preparation method of the polymer emulsion according to the present invention can improve application performance compared with surfactant-based polymer emulsions.

[0149] (iv) The method for preparing polymer emulsions according to the present invention provides a stable polymer emulsion with low viscosity.

[0150] (v) The method for preparing polymer emulsions according to the present invention provides an ideal particle size distribution in the polymer emulsion.

[0151] (vi) Polymer emulsions prepared according to the methods disclosed herein may be used in coatings, sound insulation, primers, inks, pigment dispersions, pressure-sensitive adhesives or any other application requiring high solids content.

[0152] Example

[0153] The following embodiments illustrate aspects of the currently claimed invention more fully. These embodiments are set forth in order to illustrate certain aspects of the invention and should not be construed as limiting the invention.

[0154] Components

[0155] The resin stabilizers used in Examples 1-6 and Comparative Examples 1-2 were prepared by the continuous free radical polymerization method disclosed in the detailed description.

[0156] • The polymer seed used in Examples 1-6: polystyrene was obtained from BASF SE.

[0157] • The monomers and other components in the raw materials listed in Tables 1-8, such as initiators, reducing agents and post-added components, were all purchased from Sigma Aldrich.

[0158] Example 1: The method for preparing a polymer emulsion begins with the preparation of an initial filler of a diluted resin dispersion (Table 1), which is then stirred while being heated to a reaction temperature of 88°C. Once the filler reaches 80°C, tert-butyl hydroperoxide is added to the reactor, and the mixture is held for one minute. Then, a persulfate initiator solution (44 vol.% of the total) and polymer seeds (Table 1) are added to the reactor. After holding for 15 minutes, monomer feeds 1 and 2 (Table 1) are started; all feed 1 and half of feed 2 (Table 1) are added to the reactor within 50 minutes. After 50 minutes, monomer feed 2 (Table 1) is paused for 10 minutes. Then, a small amount of persulfate initiator solution (28 vol.% of the total) is added to the reactor, monomer feed 2 (Table 1) is restarted, and monomer feed 3 (Table 1) is started. The remaining monomer feed 2 (Table 1) and all monomer feed 3 (Table 1) are added to the reactor within 50 minutes. After monomer feeds 2 and 3 (Table 1) are completed, the final persulfate initiator solution (28 vol.% of the total) is added to the reactor, and the reaction is maintained at a controlled temperature for 90 minutes. Then, a reducing agent (sodium isoascorbate) solution is added over 10 minutes, the reactor is cooled to room temperature, and the post-additives (Table 1) are added to the reactor. The final emulsion is poured through a 150 μm mesh into a collection container for filtration, and the presence of large impurities / gravel is measured.

[0159] Table 1: Polymer emulsion of Example 1

[0160]

[0161] *Non-volatile fraction per 100 monomers

[0162] **NV% is the percentage of non-volatile components.

[0163] Example 2: The method for preparing a polymer emulsion begins with the preparation of an initial filler of a diluted resin dispersion (Table 2), which is then stirred while being heated to a reaction temperature of 88°C. Once the filler reaches 80°C, tert-butyl hydroperoxide is added to the reactor, and the mixture is held for one minute. Then, a persulfate initiator solution (38.5 vol.% of total volume) and polymer seeds (Table 2) are added to the reactor. After holding for 15 minutes, monomer feeds 1 and 2 (Table 2) are started; all feed 1 (Table 2) and half of feed 2 (Table 2) are added to the reactor over 50 minutes. After 50 minutes, monomer feed 2 (Table 2) is paused for 10 minutes. Then, a small amount of persulfate initiator solution (30.8 vol.% of total volume) is added to the reactor, monomer feed 2 (Table 2) is resumed, and monomer feed 3 (Table 2) is started. The remaining monomer feed 2 (Table 2) and all monomer feed 3 (Table 2) are added to the reactor over 50 minutes. After monomer feeds 2 and 3 (Table 2) are completed, the final persulfate initiator solution (30.8 vol.% of the total) is added to the reactor, and the reaction is maintained at a controlled temperature for 90 minutes. Then, a reducing agent (sodium isoascorbate) solution is added over 10 minutes, the reactor is cooled to room temperature, and the post-additives (Table 2) are loaded into the reactor. The final emulsion is poured through a 150 μm mesh into a collection container for filtration, and the presence of large impurities / gravel is measured.

[0164] Table 2: Polymer emulsions of Example 2

[0165]

[0166] *Non-volatile fraction per 100 monomers

[0167] **NV% is the percentage of non-volatile components.

[0168] Example 3: The method for preparing a polymer emulsion begins with the preparation of an initial feedstock of a diluted resin dispersion (Table 3), which is then stirred while being heated to a reaction temperature of 88°C. Once the feedstock reaches 80°C, tert-butyl hydroperoxide is added to the reactor, and the mixture is held for one minute. Then, a persulfate initiator solution (44 vol.% of the total) and polymer seed crystals are added to the reactor. After holding for 15 minutes, monomer feeds 1 and 2 (Table 3) are started; all feed 1 (Table 3) and half of feed 2 (Table 3) are added to the reactor within 50 minutes. After 50 minutes, monomer feed 2 (Table 3) is paused for 10 minutes. Then, a small amount of persulfate initiator solution (28 vol.% of the total) is added to the reactor, monomer feed 2 (Table 3) is restarted, and monomer feed 3 (Table 3) is started. The remaining monomer feed 2 (Table 3) and all monomer feed 3 (Table 3) are added to the reactor within 50 minutes. After monomer feeds 2 and 3 (Table 3) are completed, the final persulfate initiator solution (28 vol.% of the total) is added to the reactor, and the reaction is maintained at a controlled temperature for 90 minutes. Then, a reducing agent (sodium isoascorbate) solution is added over 10 minutes, the reactor is cooled to room temperature, and the post-additives (Table 3) are added to the reactor. The final emulsion is poured through a 150 μm mesh into a collection container for filtration, and the presence of large impurities / gravel is measured.

[0169] Table 3: Polymer emulsion of Example 3

[0170]

[0171] *Non-volatile fraction per 100 monomers

[0172] **NV% is the percentage of non-volatile components.

[0173] Example 4: Preparation of Polymer Emulsion First, an initial batch of diluted resin dispersion (Table 4) was prepared and stirred while heating to a reaction temperature of 88°C. Once the batch reached 80°C, tert-butyl hydroperoxide was added to the reactor, and the mixture was held for one minute. Then, the persulfate initiator solution (44 vol.% of the total) and polymer seed crystals were added to the reactor. After holding for 15 minutes, monomer feeds 1 and 2 (Table 4) were started; all feed 1 (Table 4) and half of feed 2 (Table 4) were added to the reactor within 50 minutes. After 50 minutes, monomer feed 2 (Table 4) was paused for 10 minutes. Then, a small amount of persulfate initiator solution (28 vol.% of the total) was added to the reactor, monomer feed 2 (Table 4) was restarted, and monomer feed 3 (Table 4) was started. The remaining monomer feed 2 (Table 4) and all of monomer feed 3 (Table 4) were added to the reactor within 50 minutes. After monomer feeds 2 and 3 (Table 4) are completed, the final persulfate initiator solution (28 vol.% of the total) is added to the reactor, and the reaction is maintained at a controlled temperature for 90 minutes. Then, a reducing agent (sodium isoascorbate) solution is added over 10 minutes, the reactor is cooled to room temperature, and the post-additive (Table 4) is added to the reactor. The final emulsion is poured through a 150 μm mesh into a collection container for filtration, and the presence of large impurities / gravel is measured.

[0174] Table 4: Polymer emulsion of Example 4

[0175]

[0176] *Non-volatile fraction per 100 monomers

[0177] **NV% is the percentage of non-volatile components.

[0178] Example 5: Preparation of Polymer Emulsion First, an initial batch of diluted resin dispersion (Table 5) was prepared and stirred while heating to the reaction temperature of 88°C. Once the batch reached 80°C, tert-butyl hydroperoxide was added to the reactor, and the mixture was held for one minute. Then, a persulfate initiator solution (38.5 vol.% of total volume) and polymer seed crystals were added to the reactor. After holding for 15 minutes, monomer feed 1 (Table 5) was started; all feed 1 (Table 5) was added to the reactor within 100 minutes. After 50 minutes, a small amount of persulfate initiator solution (30.8 vol.% of total volume) was added to the reactor. After monomer feed 1 (Table 5) was completed, the final persulfate initiator solution (30.8 vol.% of total volume) was added to the reactor, and the reaction was held at a certain temperature for 60 minutes. Then, a reducing agent (sodium isoascorbate) solution was added over 10 minutes, the reactor was cooled to room temperature, and the post-additive (Table 5) was added to the reactor. The final emulsion was poured through a 150 μm mesh into a collection container to filter and measure the presence of large impurities / gravel.

[0179] Table 5: Polymer emulsion of Example 5

[0180]

[0181] *Non-volatile fraction per 100 monomers

[0182] **NV% is the percentage of non-volatile components.

[0183] Example 6: The method for preparing a polymer emulsion begins with the preparation of an initial batch of diluted resin (Table 6) dispersion and polymer seeds (Table 6), followed by stirring while heating to a reaction temperature of 88°C. Once the batch reaches 80°C, tert-butyl hydroperoxide is added to the reactor, and the mixture is held for one minute. A persulfate initiator solution (38 vol.% of the total amount) is then added to the reactor. After holding for 15 minutes, monomer feed 1 (Table 6) is started; all of feed 1 (Table 6) is added to the reactor over 50 minutes. A small amount of persulfate initiator solution (31 vol.% of the total amount) is then added to the reactor, held for 10 minutes, and then monomer feed 2 (Table 6) is started. Monomer feed 2 (Table 6) is added to the reactor over 50 minutes. After monomer feed 2 (Table 6) is completed, the final dose of persulfate initiator solution (31 vol.% of the total amount) is added to the reactor, and the reaction is held at a constant temperature for 60 minutes. Then, a reducing agent (sodium isoascorbate) solution was added over 10 minutes, the reactor was cooled to room temperature, and the post-additional additives (Table 6) were loaded into the reactor. The final emulsion was poured through a 150 μm mesh into a collection container for filtration and to measure the presence of large impurities / gravel.

[0184] Table 6: Polymer emulsion of Example 6

[0185]

[0186] *Non-volatile fraction per 100 monomers

[0187] **NV% is the percentage of non-volatile substances**

[0188] Comparative Example 1: The preparation of the polymer emulsion began with the preparation of an initial filler of a diluted resin dispersion (Table 7), which was then stirred while being heated to a reaction temperature of 88°C. Once the filler reached 80°C, tert-butyl hydroperoxide was added to the reactor, and the mixture was held for one minute. Then, a persulfate initiator solution (38.5 vol.% of the total amount) was added to the reactor. After holding for 15 minutes, monomer feeds 1 and 2 (Table 7) were started; all of feed 1 (Table 7) and half of feed 2 (Table 7) were added to the reactor over 50 minutes. After 50 minutes, monomer feed 2 (Table 7) was paused for 10 minutes. Then, a small amount of persulfate initiator solution (30.8 vol.% of the total amount) was added to the reactor, monomer feed 2 (Table 7) was restarted, and monomer feed 3 (Table 7) was started. The remaining monomer feed 2 (Table 7) and all of monomer feed 3 (Table 7) were added to the reactor over 50 minutes. After monomer feeds 2 and 3 (Table 7) were completed, the final persulfate initiator solution (30.8 vol.% of the total) was added to the reactor, and the reaction was maintained at a controlled temperature for 90 minutes. Then, a reducing agent (sodium isoascorbate) solution was added over 10 minutes, and the reactor was cooled to room temperature. During this period, the dispersion became unstable and solidified. The final emulsion could not pass through a 150 μm mesh and was discarded without further characterization.

[0189] Table 7: Polymer emulsions of Comparative Example 1

[0190]

[0191] *Non-volatile fraction per 100 monomers

[0192] Comparative Example 2: The procedure begins with the preparation of initial bottled water (Table 8), which is then stirred while being heated to the reaction temperature of 75°C. Once the bottled material reaches 75°C, tert-butyl hydroperoxide is added to the reactor, and the mixture is held for one minute before the temperature is raised to 85°C. A persulfate initiator solution (24.5 vol.% of the total volume) is then added to the reactor. After holding for 5 minutes, the monomer and persulfate initiator are fed, and the feeding continues over 160 minutes. Twenty minutes after the start of monomer and initiator feeding, the carrier resin feeding (Table 8) begins and continues for over 160 minutes. Eighty minutes after monomer feeding 1 (Table 8), the temperature is raised to 90°C, and upon completion of monomer feeding 1 (Table 8), the temperature is raised to 95°C. After the completion of the carrier resin feeding (Table 8), the reaction contents continue to be heated at 95°C for 60 minutes. Then, a reducing agent (sodium isoascorbate) solution was added over 10 minutes, the reactor was cooled to room temperature, and the post-additional additives (Table 8) were loaded into the reactor. The final emulsion was poured into a collection container through a 150 μm mesh.

[0193] Table 8: Polymer emulsions of Comparative Example 2

[0194]

[0195] *Non-volatile fraction per 100 monomers

[0196] Table 9: Properties of Polymer Emulsions

[0197]

[0198] The scope of the compositions and methods in the appended claims is not limited to the specific compositions and methods described herein, which are intended to illustrate several aspects of the claims, and any functionally equivalent compositions and methods are intended to fall within the scope of the claims. Various modifications to the methods other than those shown and described herein are intended to fall within the scope of the appended claims. Furthermore, although only certain representative compositions and method steps disclosed herein are specifically described, other combinations of these compositions and method steps are also intended to fall within the scope of the appended claims, even if not specifically stated. Therefore, combinations of steps, elements, components, or ingredients may be expressly referred to herein; however, fewer other combinations of steps, elements, components, and ingredients may be included, even if not expressly stated. As used herein, the term "comprising" and its variations are used synonymously with the term "including" and its variations, and are open-ended and non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various embodiments, the terms “consisting essentially of” and “consisting of” may be used in place of “comprising” and “including” to provide more specific embodiments of the invention, and are also disclosed. Except as indicated in the embodiments or elsewhere, all figures representing quantities of ingredients, reaction conditions, etc., used in the specification and claims should be understood, rather than as an attempt to limit the application of the equivalence principle to the scope of the claims, and should be interpreted in accordance with the number of significant figures and common rounding methods.

[0199] Results Discussion

[0200] The results in Table 9 show the high solids content in the polymer emulsions prepared by the method according to the invention. Examples (Examples 1 to 6) produced using the method of the invention demonstrate that adding polymer seeds to the resin-stabilized emulsion polymerization results in a bimodal particle size distribution, thus enabling the production of resin-stabilized latexes with a high solids content (NV%) of at least 55 wt.% and low viscosity (<1000 cPs).

[0201] For comparison, the process of Example 2 was repeated without polymer seed, as described in Comparative Example 1, which resulted in extremely high viscosity to the freezing point. This demonstrates the limitations of NV% in conventional resin-stabilized systems and the advantages of the currently claimed method.

[0202] The second comparative example, Comparative Example 2, demonstrates a method of semi-batch feeding of resin into the reaction, ultimately resulting in a bimodal particle size distribution. Comparative Example 2 differs from the currently claimed method in the use of polymer seeds, and the resin is fed into the reactor separately. The currently claimed method is an improved method for preparing polymer emulsions that eliminates the need for protective colloids requiring large amounts of stabilizers, thus limiting water resistance. Furthermore, polymer emulsions containing protective colloids and high solids content (greater than 55 wt.%) also suffer from poor rheological properties and excessively high viscosity, making them unsuitable for coating.

[0203] The improved properties of the polymer emulsions prepared by this invention are driven by the weight ratio of the polymer seed to the resin. However, this is not the only parameter driving the properties of the polymer emulsion. Adding resin stabilizers prepared via a continuous free radical polymerization process to the reaction mixture to prepare polymer emulsions can also achieve unique properties and morphologies. Particle size distribution is a factor affecting the viscosity and adhesive properties of polymer emulsions. In the methods disclosed herein, optimization of the reaction mixture components drives the desired particle size distribution. A relatively narrow particle size distribution, as shown in Table 9, has a significant impact on achieving the desired adhesive properties.

[0204] Test methods

[0205] Molecular weight determination: Gel permeation chromatography (GPC) spectra were acquired using a Waters 2695 instrument, and the molecular weight of the polymers was determined using tetrahydrofuran (THF) as the mobile phase at 40 °C and with a differential refractive index detector. Elution times calibrated against a polystyrene molecular weight standard were used to analyze the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of all samples. The number-average molecular weight (Mn) is the statistical average molecular weight of all polymer chains in the polymer and is defined as follows:

[0206] M n =(ΣN i M i ) / ΣN i

[0207] Where Mi is the molecular weight of the chain, and Ni is the number of chains of that molecular weight.

[0208] Weight-average molecular weight (Mw) is defined as follows:

[0209] M w =(ΣN i M i 2 ) / ΣN i

[0210] Compared to Mn, Mw takes into account the molecular weight of the chain when determining its contribution to the average molecular weight. The heavier the chain, the greater its contribution to Mw.

[0211] A higher weight-average molecular weight (Mz) can be defined by the following equation:

[0212] M z =(ΣN i M i 3 ) / ΣN i

[0213] Solid content determination: The solid content of the polymer emulsion was measured by gravimetric method by drying approximately 0.5 g to approximately 2 g of dispersion sample in a 140°C oven for 1 hour. The solid content was measured using a CEM microwave solids analyzer. The non-volatile (NV%) content was measured by gravimetric method using a CEM Smart System 5 microwave moisture analyzer.

[0214] Viscosity determination: The viscosity of the polymer emulsion was measured using a Brookfield RV viscometer at 60 RPM (rotor 63).

[0215] Particle size determination, including volume average particle size: The particle size of particles in polymer emulsions was measured using dynamic light scattering technology with a nano-flex particle size analyzer from Microtrac.

[0216] Glass transition temperature determination: Glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC) using the hot-cold-hot method according to ASTM D 3418-12e1.

Claims

1. A method of preparing a polymer emulsion comprising the steps of: i) providing a resin dispersion comprising at least one resin in water; ii) adding at least one polymer seed and a polymerization mixture to the resin dispersion, the polymerization mixture comprising at least one co-polymerizable monomer; and iii) preparing a polymer emulsion in water by free radical emulsion polymerization of the polymerization mixture, the resin dispersion, and the polymer seed; wherein the polymer emulsion has a solids content of at least 55 wt.% based on the total weight of the polymer emulsion, wherein the method further comprises the step of adding at least one surfactant to the resin dispersion in an amount ranging from < 0.10 wt.% based on the total weight of the polymer emulsion, wherein the at least one polymer seed is polystyrene, wherein the at least one polymer seed comprises at least one acid monomer selected from the group consisting of: ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, and vinyl phosphonic acids, and wherein the at least one co-polymerizable monomer is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl acetic acid, vinyl lactic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamidomethylpropane sulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, styrene, a-methylstyrene, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 1,4-butanediol diacrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, isoamyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, isoamyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, glycidyl methacrylate, butenyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, ureido methacrylate, acrylamide, methacrylamide, N-butoxymethyl methacrylamide, N-hydroxymethyl acrylamide, N-hydroxymethyl methacrylamide, diacetone acrylamide, vinyl acetate, and acrylonitrile.

2. The method of claim 1, wherein, The at least one resin is selected from the group consisting of poly(meth)acrylates and polystyrene.

3. The method of claim 1, wherein, The at least one resin is present in an amount ranging from 5 wt.% to 40 wt.% based on the total weight of the resin dispersion.

4. The method of claim 2, wherein, The at least one resin is present in an amount ranging from 5 wt.% to 40 wt.% based on the total weight of the resin dispersion.

5. The method of claim 1, wherein, The at least one polymer seed comprises < 1.0 wt.% of at least one acid monomer based on the total weight of the polymer seed.

6. The method of claim 2, wherein, The at least one polymer seed comprises < 1.0 wt.% of at least one acid monomer based on the total weight of the polymer seed.

7. The method of claim 3, wherein, The at least one polymer seed comprises < 1.0 wt.% of at least one acid monomer based on the total weight of the polymer seed.

8. The method of claim 4, wherein, The at least one polymer seed comprises < 1.0 wt.% of at least one acid monomer based on the total weight of the polymer seed.

9. The method of any one of claims 1 to 8, wherein, The at least one polymer seed has a number average particle size in the range of 10 nm to 50 nm as determined according to dynamic light scattering method.

10. The method of any one of claims 1 to 8, wherein, The at least one polymer seed has a weight average molecular weight in the range of 10,000 g / mol to 500,000 g / mol as determined according to gel permeation chromatography method.

11. The method of claim 9, wherein, The at least one polymer seed has a weight average molecular weight in the range of 10,000 g / mol to 500,000 g / mol as determined according to gel permeation chromatography method.

12. The method of any one of claims 1 to 8, wherein, The at least one polymer seed is present in an amount ranging from 0.1 wt.% to 5.0 wt.% based on the total weight of the polymer emulsion.

13. The method of claim 11, wherein, The at least one polymer seed is present in an amount ranging from 0.1 wt.% to 5.0 wt.% based on the total weight of the polymer emulsion.

14. The method of any one of claims 1 to 8, wherein, The solid content of the at least one polymer seed is in the range of 1.0 wt.% to 50.0 wt.%.

15. The method of claim 13, wherein, The solid content of the at least one polymer seed is in the range of 1.0 wt.% to 50.0 wt.%.

16. The method of any one of claims 1 to 8, wherein, The at least one co-polymerizable monomer is present in an amount ranging from 15 wt.% to 65 wt.% based on the total weight of the polymer emulsion.

17. The method of claim 15, wherein, The at least one co-polymerizable monomer is present in an amount ranging from 15 wt.% to 65 wt.% based on the total weight of the polymer emulsion.

18. The method of any one of claims 1 to 8, wherein, The polymerization mixture further comprises at least one water-soluble initiator.

19. The method of claim 17, wherein, The polymerization mixture further comprises at least one water-soluble initiator.

20. The method of claim 18, wherein, The at least one water-soluble initiator is selected from peroxides.

21. The method of claim 19, wherein, The at least one water-soluble initiator is selected from peroxides.

22. The method of claim 20 or 21, wherein, The at least one water-soluble initiator is selected from the group consisting of ammonium or alkali metal salts of peroxodisulfates.

23. The method of claim 18, wherein, The at least one water-soluble initiator is present in an amount ranging from 0.10 wt.% to 5.0 wt.% based on the total weight of the monomers in the polymerization mixture.

24. The method of claim 20, wherein, The at least one water-soluble initiator is present in an amount ranging from 0.10 wt.% to 5.0 wt.% based on the total weight of the monomers in the polymerization mixture.

25. The method of claim 1, wherein, The weight ratio of the at least one polymer seed to the at least one co-polymerizable monomer is in the range of 0.2: 100 to 5:

100.

26. The method of claim 1, wherein, The weight ratio of the at least one resin to the at least one co-polymerizable monomer is in the range of 5: 100 to 40:

100.

27. The method of any one of claims 1 to 8, wherein, The polymer emulsion has a solids content of at least 60 wt.%, based on the total weight of the polymer emulsion.

28. The method of claim 26, wherein, The polymer emulsion has a solids content of at least 60 wt.%, based on the total weight of the polymer emulsion.

29. The method of any one of claims 1 to 8, wherein, The polymer emulsion has a glass transition temperature in the range of -60°C to 120°C, as determined by dynamic scanning calorimetry.

30. The method of claim 28, wherein, The polymer emulsion has a glass transition temperature in the range of -60°C to 120°C, as determined by dynamic scanning calorimetry.

31. The method of any one of claims 1 to 8, wherein, The polymer emulsion has a viscosity in the range of 50 cps to 10,000 cps, as measured at 25°C at 60 RPM using a viscometer with a #63 rotor.

32. The method of claim 30, wherein, The polymer emulsion has a viscosity in the range of 50 cps to 10,000 cps, as measured at 25°C at 60 RPM using a viscometer with a #63 rotor.

33. The method of any one of claims 1 to 8, wherein, The polymer emulsion contains particles having a volume average particle size in the range of 100 nm to 1000 nm, as determined by dynamic light scattering.

34. The method of claim 32, wherein, The polymer emulsion contains particles having a volume average particle size in the range of 100 nm to 1000 nm, as determined by dynamic light scattering.

35. The method of any one of claims 1 to 8, wherein, The step of preparing the polymer emulsion in water by free radical emulsion polymerization is a semi-batch process.

36. The method of claim 34, wherein, The step of preparing the polymer emulsion in water by free radical emulsion polymerization is a semi-batch process.

37. The method of claim 33, wherein, The polymer emulsion comprises particles present in a bimodal or multimodal particle size distribution.

38. The method of claim 34, wherein, The polymer emulsion comprises particles present in a bimodal or multimodal particle size distribution.

39. A polymer emulsion obtainable by the process according to any one of claims 1 to 38.

40. The polymer emulsion of claim 39, wherein, The polymer emulsion is suitable for use in the preparation of adhesives, composite films, protective film laminates, coatings, soundproofing, primers, inks, or pigment dispersions. The polymer emulsion is suitable for use in the preparation of adhesives, composite films, protective film laminates, coatings, soundproofing, primers, inks, or pigment dispersions.

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