阅读说明：本技术 聚合颗粒的水性分散体 (Aqueous dispersions of polymeric particles ) 是由 李岩 陈军宇 沈澄 J·勃林 龚志娟 王涛 于 2018-10-16 设计创作，主要内容包括：聚合颗粒的水性分散体包含乳液聚合物和重均分子量在450到1,500g/mol的范围内的聚环氧烷,并且具有低VOC的水性涂料组合物包含所述水性分散体,并且使由其制备的涂料具有改善的水漂白耐受性和硬度。(An aqueous dispersion of polymeric particles comprises an emulsion polymer and a polyalkylene oxide having a weight average molecular weight in the range of 450 to 1,500g/mol, and an aqueous coating composition having a low VOC comprises the aqueous dispersion and results in coatings prepared therefrom having improved water bleach resistance and hardness.)

1. An aqueous dispersion of polymeric particles comprising an emulsion polymer and a polyalkylene oxide having a weight average molecular weight in the range of from 450 to 1,500g/mol,

wherein the emulsion polymer comprises structural units of an ethylenically unsaturated phosphorous acid monomer and/or a salt thereof,

wherein the polyalkylene oxide has the structure of formula (I),

R₁-O-(AO)_m-R₂ (I)，

wherein R is₁And R₂Each independently represents a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated alkyl group having 1 to 22 carbon atoms; AO represents a butylene oxide unit or a combination of a butylene oxide unit and a propylene oxide unit; and m is an integer from 5 to 23; and is

Wherein the amount of the polyalkylene oxide in the polymeric particles is 50 wt.% or more based on the total weight of polyalkylene oxide in the aqueous dispersion.

2. The aqueous dispersion of claim 1, wherein the polyalkylene oxide is present in the polymeric particles in an amount of from 0.5 to 30 weight percent, based on the weight of the emulsion polymer.

3. The aqueous dispersion according to any of the preceding claims, wherein the polyalkylene oxide has a weight average molecular weight of from 500 to 1,000 g/mol.

4. The aqueous dispersion of any one of the preceding claims, wherein R₁And R₂Is an alkyl group having 4 to 12 carbon atoms, and m is 5 to 15.

5. The aqueous dispersion of any one of the preceding claims, wherein the amount of the polyalkylene oxide in the polymeric particles is 70 wt.% or more based on the total weight of polyalkylene oxide in the aqueous dispersion.

6. The aqueous dispersion of any one of the preceding claims, wherein the polymeric particles have a minimum film forming temperature of less than 23 ℃.

7. The aqueous dispersion of any one of the preceding claims, wherein the emulsion polymer comprises from 0.1 to 10 weight percent structural units of the ethylenically unsaturated phosphorous acid monomer and/or salt thereof, based on the weight of the emulsion polymer.

8. The aqueous dispersion of any one of the preceding claims, wherein the ethylenically unsaturated phosphorous acid monomer is selected from the group consisting of: phosphoric ethyl (meth) acrylate, phosphoric propyl (meth) acrylate, phosphoric butyl (meth) acrylate, or mixtures thereof.

9. The aqueous dispersion of any of the preceding claims, wherein the emulsion polymer further comprises from 0.1 to 5% by weight, based on the weight of the emulsion polymer, of structural units of an ethylenically unsaturated monomer bearing at least one functional group selected from the group consisting of: amide, carboxyl, carboxylic anhydride, sulfonate, sulfate, or mixtures thereof.

10. The aqueous dispersion of any one of the preceding claims, wherein the polymeric particles have a measured Tg of from-20 ℃ to 50 ℃.

11. The aqueous dispersion of any one of the preceding claims, wherein the polymeric particles have a particle size of from 60 to 200 nm.

12. The aqueous dispersion of any one of the preceding claims formed by emulsion polymerizing monomers in an aqueous medium in the presence of the polyalkylene oxide, wherein the monomers comprise the ethylenically unsaturated phosphorous acid monomer and/or salt thereof.

13. A method of making an aqueous dispersion of polymeric particles comprising:

polymerizing monomers in an aqueous medium in the presence of a polyalkylene oxide to obtain a dispersion of polymeric particles,

wherein the monomer comprises an ethylenically unsaturated phosphorous acid monomer and/or a salt thereof,

wherein the polyalkylene oxide having a weight average molecular weight in the range of 450 to 1,500g/mol has the structure of formula (I),

R₁-O-(AO)_m-R₂ (I)，

wherein R is₁And R₂Each independently represents a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated alkyl group having 1 to 22 carbon atoms; AO represents a butylene oxide unit or a combination of a butylene oxide unit and a propylene oxide unit; and m is an integer from 5 to 23; and is

Wherein the amount of the polyalkylene oxide in the polymeric particles is 50 wt.% or more based on the total weight of polyalkylene oxide in the aqueous dispersion.

14. An aqueous coating composition comprising an aqueous dispersion of polymeric particles according to any one of claims 1 to 12.

15. The aqueous coating composition of claim 14, further comprising zero to less than 2% of a coalescing agent by dry weight of the aqueous dispersion of polymeric particles.

Technical Field

The present invention relates to aqueous dispersions of polymeric particles and aqueous coating compositions comprising the same.

Background

Aqueous or water-based coating compositions are becoming more and more important than solvent-based coating compositions due to fewer environmental issues. The coating industry has been interested in developing coating compositions that are free of, or have significantly reduced or low Volatile Organic Compounds (VOCs).

In gloss applications, the binder typically has a glass transition temperature near or above room temperature, where film formation is facilitated by coalescents and/or solvents. One common method of minimizing VOC is to include a non-volatile coalescing agent, such as Optifilm Enhancer 400 coalescing agent from eastman chemical company. However, the use of such non-volatile coalescents has significantly increased cost and challenges that compromise performance such as hardness and/or water bleach resistance.

Accordingly, there is a need to develop a new solvent-free binder suitable for water-based paint formulations having lower VOC levels and improved performance compared to paints containing conventional coalescents.

Disclosure of Invention

The present invention provides a novel aqueous dispersion of polymeric particles prepared by incorporating a specific polyalkylene oxide during polymerization. The aqueous dispersions of the present invention can provide a minimum film forming temperature that is low enough to form a film at room temperature without the use of a coalescing agent. Aqueous coating compositions comprising such aqueous dispersions have lower VOC and may provide coatings made therefrom with improved Koenig hardness and water bleach resistance compared to coating compositions comprising a combination of conventional binders and conventional coalescents under the same loading.

In a first aspect, the invention is an aqueous dispersion of polymeric particles comprising an emulsion polymer and a polyalkylene oxide having a weight average molecular weight in the range of from 450 to 1,500g/mol,

wherein the emulsion polymer comprises structural units of an ethylenically unsaturated phosphorous acid monomer and/or a salt thereof, wherein the polyalkylene oxide has the structure of formula (I),

R₁-O-(AO)_m-R₂ (I)，

wherein R is₁And R₂Each independently represents a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated alkyl group having 1 to 22 carbon atoms; AO represents a butylene oxide unit or a combination of a butylene oxide unit and a propylene oxide unit; and m is an integer from 5 to 23; and is

Wherein the amount of polyalkylene oxide in the polymeric particles is 50 wt.% or more based on the total weight of polyalkylene oxide in the aqueous dispersion.

In a second aspect, the present invention is a method of making an aqueous dispersion of polymeric particles of the first aspect.

In a third aspect, the present invention is an aqueous coating composition comprising an aqueous dispersion of the polymeric particles of the first aspect.

Detailed Description

"acrylic acid" in the present invention includes (meth) acrylic acid, (meth) alkyl acrylates, (meth) acrylamides, (meth) acrylonitrile, and modified forms thereof, such as (meth) hydroxyalkyl acrylates. Throughout this document, the word fragment "(meth) acryl" refers to both "methacryl" and "acryl". For example, (meth) acrylic acid refers to methacrylic acid and acrylic acid, and methyl (meth) acrylate refers to methyl methacrylate and methyl acrylate.

The "aqueous dispersion of polymeric particles" in the present invention means polymer particles dispersed in an aqueous medium. By "aqueous medium" in the present invention is meant water and 0 to 30 wt.% of water-miscible compound(s), such as alcohols, glycols, glycol ethers, glycol esters, and the like, based on the weight of the medium.

The aqueous dispersion of polymeric particles comprising an emulsion polymer and a polyalkylene oxide can be prepared by polymerizing (e.g., emulsion polymerizing) monomers in an aqueous medium in the presence of a polyalkylene oxide.

Emulsion polymers suitable for use in the present invention may comprise structural units of one or more ethylenically unsaturated phosphorous acid monomers and/or salts thereof. The ethylenically unsaturated phosphorous acid monomer may be a dihydrogen phosphate ester of an alcohol, wherein the alcohol contains or is substituted with a polymerizable vinyl or olefinic group. Ethylenically unsaturated phosphorous acid monomers may include phosphoalkyl (meth) acrylates, such as phosphoethyl (meth) acrylate, phosphopropyl (meth) acrylate, phosphobutyl (meth) acrylate, salts thereof, and mixtures thereof; CH (CH)₂＝C(R)-C(O)-O-(R_pO)_n-P(O)(OH)₂Wherein R is H or CH₃，R_pAlkyl, and n ═ 1-10, such as sipmer PAM-100, sipmer PAM-200, and sipmer PAM-300, all available from sumay (Solvay); phosphoric acid alkoxy (meth) acrylates, such as ethylene glycol (meth) acrylate phosphate, diethylene glycol (meth) acrylate phosphate, triethylene glycol (meth) acrylate phosphate, propylene glycol (meth) acrylate phosphate, dipropylene glycol (meth) acrylate phosphate, tripropylene glycol (meth) acrylate phosphate, salts thereof, and mixtures thereof. Preferred ethylenically unsaturated phosphorus-containing monomers are selected from the group consisting of: phosphoric ethyl (meth) acrylate, phosphoric propyl (meth) acrylate, phosphoric butyl (meth) acrylate, and salts thereof; more preferably, phosphoethyl methacrylate (PEM). The emulsion polymer may comprise, based on the weight of the emulsion polymer, 0.1 wt.% or more, 0.2 wt.% or more, 0.3 wt.% or more, 0.4 wt.% or more, 0.5 wt.% or more, 0.6 wt.% or more, 0.7 wt.% or more, 0.8 wt.% or more, 0.9 wt.% or more, 1 wt.% or more, 1.1 wt.% or more, or even 1.2 wt.% or more, and at the same time 10 wt.% or less, 8 wt.% or less, 6 wt.% or less, 5 wt.% or less, 4.5 wt.% or less, 4 wt.% or less, 3.5 wt.% or less, 3 wt.% or less, 2.5 wt.% or less, 2 wt.% or less, or even 1.5 wt.% or less of structural units of ethylenically unsaturated phosphorous acid monomers and/or salts thereof. The weight of the emulsion polymer herein in the present invention means the dry weight of the emulsion polymer。

Emulsion polymers suitable for use in the present invention may comprise structural units of one or more ethylenically unsaturated monomers bearing at least one functional group selected from the group consisting of: amide, carboxyl, carboxylic anhydride, sulfonate, sulfate, or mixtures thereof. Suitable ethylenically unsaturated monomers bearing at least one functional group may include, for example, α, β -ethylenically unsaturated carboxylic acids or anhydrides thereof, such as (meth) acrylic acid, Itaconic Acid (IA), fumaric acid, (meth) acrylic anhydride, maleic anhydride, or mixtures thereof; sodium Styrene Sulfonate (SSS), Sodium Vinyl Sulfonate (SVS), 2-acrylamido-2-methylpropanesulfonic Acid (AMPS), methacrylamide, acrylamide, or mixtures thereof. Preferred ethylenically unsaturated monomers having at least one functional group include methacrylamide, acrylamide, or mixtures thereof. The emulsion polymer may comprise, based on the weight of the emulsion polymer, zero or more, 0.1 wt.% or more, 0.2 wt.% or more, 0.3 wt.% or more, 0.4 wt.% or more, 0.5 wt.% or more, 0.6 wt.% or more, 0.7 wt.% or more, 0.8 wt.% or more, or even 1.0 wt.% or more, and at the same time 10 wt.% or less, 8 wt.% or less, 6 wt.% or less, 5 wt.% or less, 4 wt.% or less, 3.5 wt.% or less, 3 wt.% or less, 2.5 wt.% or less, 2.2 wt.% or less, 2 wt.% or less, 1.8 wt.% or less, 1.5 wt.% or less, or even 1.2 wt.% or less of structural units of an ethylenically unsaturated monomer having at least one functional group.

Emulsion polymers suitable for use in the present invention may comprise structural units of one or more monoethylenically unsaturated nonionic monomers other than those described above. Herein, "nonionic monomer" refers to a monomer that does not carry an ionic charge between pH 1-14. Monoethylenically unsaturated nonionic monomers can include (meth) acrylic acid and alkyl esters having an alkyl group of 1 to 20 carbon atoms, 1 to 10 carbon atoms, or 1 to 8 carbon atoms examples of suitable monoethylenically unsaturated nonionic monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or combinations thereof; (meth) acrylonitrile; ureido functional monomers, such as hydroxyethyl ethylene urea methacrylate; monomers with acetoacetoxy functionality, such as acetoacetoxyethyl methacrylate (AAEM); monomers bearing carbonyl-containing groups, such as diacetone acrylamide (DAAM); vinyl aromatic monomers including styrene and substituted styrenes such as alpha-methylstyrene, p-methylstyrene, t-butylstyrene, vinyl toluene, or mixtures thereof; butadiene; alpha-olefins such as ethylene, propylene and 1-decene; vinyl acetate, vinyl butyrate, vinyl versatate and other vinyl esters; glycidyl (meth) acrylate; or a combination thereof. Preferred monoethylenically unsaturated nonionic monomers are selected from the group consisting of: methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, styrene, or mixtures thereof. The emulsion polymer may comprise 50 wt.% or more, 60 wt.% or more, 70 wt.% or more, 80 wt.% or more, 90 wt.% or more, or even 95 wt.% or more, and at the same time 99.5 wt.% or less, 99 wt.% or less, or even 98 wt.% or less structural units of a monoethylenically unsaturated nonionic monomer, based on the weight of the emulsion polymer.

The emulsion polymers suitable for use in the present invention may also comprise one or more polyethylenically unsaturated monomers. Suitable polyethylenically unsaturated monomers may include alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, 1,1, 1-trimethylolpropane di (meth) acrylate, or pentaerythritol trimethacrylate; divinylbenzene, vinyl (meth) acrylates; allyl (meth) acrylate, N-methylenebisacrylamide, and the like; or mixtures thereof. The emulsion polymer may comprise, based on the weight of the emulsion polymer, zero or more, 0.1 wt.% or more, 0.2 wt.% or more, or even 0.5 wt.% or more, and at the same time 5 wt.% or less, 4 wt.% or less, 3 wt.% or less, 2 wt.% or less, or even 1 wt.% or less of structural units of the polyethylenically unsaturated monomer.

The total weight concentration of the above-described structural units in the emulsion polymer may be equal to 100%. The type and amount of monomers described above can be selected so that the resulting emulsion polymer has a glass transition temperature (T) suitable for different applications_g). The measured Tg of the polymeric particles may be in the range of-60 ℃ to 100 ℃, -20 ℃ to 50 ℃, -10 ℃ to 30 ℃. As used herein, "measured Tg" refers to the glass transition temperature as determined by Differential Scanning Calorimetry (DSC) according to the test method described in the examples section below.

The polymeric particles in the aqueous dispersion further comprise one or more polyalkylene oxides. Polyalkylene oxides suitable for use in the present invention may have the structure of formula (I),

R₁-O-(AO)_m-R₂ (I)

wherein R is₁And R₂Each independently represents a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated alkyl group having 1 to 22 carbon atoms; AO represents a butylene oxide unit (-C)₄H₈O-) or butylene oxide unit and propylene oxide unit (-C)₃H₆A combination of O-; and m is an integer of 5 to 23, preferably 5 to 15. In some embodiments, R₁And R₂At least one of which is an alkyl group, preferably having from 4 to 12 carbon atoms. In some further embodiments, R₁And R₂One of which is an alkyl group having 4 to 12 carbon atoms, and the other is a hydrogen atom. Preferably, AO represents a combination of butylene oxide units and propylene oxide units, i.e., the polyalkylene oxide is a polypropylene oxide-polybutylene oxide copolymer. The polyalkylene oxide may be a block or random polymer. Preferred polyalkylene oxides are block or random polypropylene oxide-polypropylene oxide copolymers.

Polyalkylene oxides suitable for use in the present invention may comprise from zero to 90 weight percent of units derived from propylene oxide and from 100 to 10 weight percent of units derived from butylene oxide. For example, the amount of units derived from butylene oxide (i.e., butylene oxide units) can be 10 wt.% or more, 15 wt.% or more, 20 wt.% or more, 25 wt.% or more, 30 wt.% or more, 35 wt.% or more, 40 wt.% or more, or even 45 wt.% or more, and at the same time 100 wt.% or less, 95 wt.% or less, 90 wt.% or less, 85 wt.% or less, 80 wt.% or less, 70 wt.% or less, 65 wt.% or less, 60 wt.% or less, 55 wt.% or less, or even 50 wt.% or less, based on the total weight of butylene oxide units and propylene oxide units. The amount of units derived from propylene oxide (i.e., propylene oxide units) can be zero or more, 5 wt.% or more, 10 wt.% or more, 15 wt.% or more, 20 wt.% or more, 30 wt.% or more, 35 wt.% or more, 40 wt.% or more, or even 45 wt.% or more, and at the same time 90 wt.% or less, 85 wt.% or less, 80 wt.% or less, 75 wt.% or less, 70 wt.% or less, 65 wt.% or less, or even 60 wt.% or less, based on the total weight of butylene oxide units and propylene oxide units.

The polyalkylene oxides suitable for use in the present invention may have a weight average molecular weight of 1,500g/mol or less, for example 450g/mol or more, 500g/mol or more, 550g/mol or more, 600g/mol or more, 620g/mol or more, 650g/mol or more, 680g/mol or more, 700g/mol or more, 720g/mol or more or even 750g/mol or more, and at the same time, 1,500g/mol or less, 1,400g/mol or less, 1,300g/mol or less, 1,200g/mol or less, 1,100g/mol or less, 1,000g/mol or less, 980g/mol or less, 950g/mol or less, 920g/mol or less, 900g/mol or less, 880g/mol or less, 850g/mol or less, or, 820g/mol or less, 800g/mol or less, 780g/mol or less, or even 770g/mol or less. The weight average molecular weight can be determined by Gel Permeation Chromatography (GPC) as described in the examples section below.

The polyalkylene oxide can be present in the polymeric particle in an amount of 0.5 weight percent or more, 1 weight percent or more, 1.5 weight percent or more, 2 weight percent or more, 2.5 weight percent or more, 3 weight percent or more, 3.5 weight percent or more, 4 weight percent or more, 4.5 weight percent or more, 5 weight percent or more, 5.5 weight percent or less, 6 weight percent or more, 6.5 weight percent or less, 7 weight percent or more, 7.5 weight percent or more, 8 weight percent or more, 8.5 weight percent or more, 9 weight percent or more, 9.5 weight percent or more, or even 10 weight percent or more, and at the same time 30 weight percent or less, 28 weight percent or less, 26 weight percent or less, 25 weight percent or less, 24 weight percent or less, 22 weight percent or less, 20 weight percent or less, based on the weight of the emulsion polymer in the polymeric particle, 19 wt% or less, 18 wt% or less, 17 wt% or less, 16 wt% or less, 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, or even 11 wt% or less.

The polymeric particles in the aqueous dispersion may have an average particle size of 30 to 500 nanometers (nm), 50 to 300nm, or 80 to 200 nm. Particle size herein refers to the Z average particle size and can be measured by a Brookhaven BI-90Plus particle size analyzer.

The aqueous dispersion of polymeric particles of the present invention may be prepared by polymerizing, preferably emulsion polymerizing, the monomers described above in an aqueous medium in the presence of a polyalkylene oxide. The polyalkylene oxide may be added before or during the polymerization of the monomer or a combination thereof. The polyalkylene oxide can be added to the monomer, or to a polymer seed (e.g., polystyrene seed), for injection into the reactor, or dispersed in the monomer. In one embodiment, the polyalkylene oxide is mixed with the monomer prior to polymerization of the monomer. Without being bound by theory, after the polymerization process, all or a major portion of the polyalkylene oxide attaches to the surface of the polymeric particle and/or is embedded in the polymeric particle (both referred to as "polyalkylene oxide in the polymeric particle"). After the preparation of the polymeric particles, a small amount of polyalkylene oxide may optionally be present in the aqueous medium of the aqueous dispersion obtained. For example, the polyalkylene oxide in the polymeric particles can be present in an amount of 50 weight percent or more, 55 weight percent or more, 60 weight percent or more, 65 weight percent or more, 70 weight percent or more, 75 weight percent or more, 80 weight percent or more, 85 weight percent or more, 87 weight percent or more, about 90 weight percent or more, 95 weight percent or more, 97 weight percent or more, 98 weight percent or more, 99 weight percent or more, or even 100 weight percent based on the total weight of polyalkylene oxide in the aqueous dispersion (i.e., the total weight of polyalkylene oxide in the polymeric particles and in the aqueous medium of the aqueous dispersion).

The monomers can be added in the form of a solvent-free or emulsion in water; or one or more additions or a continuous, linear or nonlinear addition during the reaction period to prepare the polymeric particles. The total weight concentration of monomers described above for preparing polymeric particles may be equal to 100%. The dosage of such monomers based on the total weight of the monomers is substantially the same as the amount of each of these monomers as structural units in the emulsion polymer, based on the weight of the emulsion polymer.

Suitable temperatures for the polymerization of the monomers may be below 100 ℃, in the range of 30 ℃ to 95 ℃ or in the range of 50 ℃ to 92 ℃. Multistage emulsion polymerization using the above monomers can be utilized, wherein at least two stages are formed sequentially, and typically a multistage polymer comprising at least two polymer compositions is formed.

Free radical initiators may be used in the polymerization process. The polymerization process may be a thermally initiated or redox initiated emulsion polymerization. Examples of suitable free radical initiators include hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium and/or alkali metal persulfates, sodium perborate, perphosphoric acid and its salts; ammonium or alkali metal salts of potassium permanganate and peroxydisulfuric acid. Free radical initiators may generally be used at levels of from 0.01 wt% to 3.0 wt%, based on the total weight of the monomers. Redox systems comprising the above-mentioned initiators and suitable reducing agents can be used in the polymerization process. Examples of suitable reducing agents include sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, alkali metal and ammonium salts of sulfur-containing acids (such as sodium sulfite, bisulfite, thiosulfate, hyposulfite, sulfide, hydrosulfide or dithionite), formamidine sulfinic acid, acetone bisulfite, glycolic acid, hydroxymethylsulfonic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid, and salts of the foregoing acids. Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium or cobalt may be used to catalyze the redox reaction. A chelating agent for the metal may optionally be used.

One or more surfactants may be used in the polymerization process. The surfactant may be added prior to or during the polymerization of the monomers or a combination thereof. A portion of the surfactant may also be added after polymerization. These surfactants may include anionic and/or nonionic emulsifiers. The surfactant may be a reactive surfactant, for example, a polymerizable surfactant. Examples of suitable surfactants include alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates; an alkyl sulfonic acid; a sulfosuccinate salt; a fatty acid; and ethoxylated alcohols or phenols. Preferably, alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfate surfactants are used. The surfactant used is typically zero to 10 wt.%, 0.5 wt.% to 3 wt.%, or 0.8 wt.% to 1.5 wt.%, based on the total weight of the monomers.

One or more chain transfer agents may be used in the polymerization process. Examples of suitable chain transfer agents include 3-mercaptopropionic acid, n-dodecyl mercaptan, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, thiophenol, alkyl mercaptans azelaic acid, or mixtures thereof. The chain transfer agent may be used in an effective amount to control the molecular weight of the emulsion polymer. The chain transfer agent may be used in an amount of zero to 5 wt%, 0.05 wt% to 1 wt%, or 0.1 wt% to 0.3 wt%, based on the total weight of the monomers.

After completion of the polymerization process, the resulting aqueous dispersion may be neutralized to a pH value, e.g., at least 7, 7 to 10, or 8 to 9, by one or more bases. Examples of suitable bases include ammonia; alkali metal or alkaline earth metal compounds, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, sodium carbonate; primary, secondary and tertiary amines, such as triethylamine, ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, diethylamine, dimethylamine, di-n-propylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, dimethylethanolamine, diisopropanolamine, morpholine, ethylenediamine, 2-diethylaminoethylamine, 2, 3-diaminopropane, 1, 2-propanediamine, neopentyldiamine, dimethylaminopropylamine, hexamethylenediamine, 4, 9-dioxadodecane-1, 12-diamine, polyethyleneimine or polyvinylamine; aluminum hydroxide; or mixtures thereof. The aqueous dispersion of the present invention may have a solids content of from 20 to 70 wt% or from 40 to 60 wt%.

The aqueous dispersions of the present invention exhibit good film-forming properties at room temperature. For example, the aqueous dispersions of the present invention exhibit a lower Minimum Film Forming Temperature (MFFT) compared to blends without the polyalkylene oxide binder or the emulsion polymer and polyalkylene oxide. The MFFT is the lowest temperature at which the polymer particles of an aqueous dispersion will coalesce with one another and form a continuous film when the volatile component (e.g., water) evaporates. The MFFT may be determined according to the test method described in the examples section below.

The aqueous dispersions of polymeric particles of the present invention are suitable for use in coating applications without the use of coalescents. The aqueous dispersions of the present invention can provide coating films with comparable performance properties, such as hiding power, whiteness, gloss, scrub resistance, and/or stain resistance, as compared to coating compositions comprising conventional binders and high VOC coalescents (defined by ISO 17895-2005), such as Texanol ester alcohols from eastman chemical company. OE-400 aqueous dispersions of the invention, as defined by ISO17895-2005, such as by eastman chemical company, loaded identically, may also provide coating films with improved Koenig hardness and water bleach resistance while not requiring coalescents, as compared to coating compositions comprising conventional binders and typical zero VOC coalescents.

The aqueous coating composition of the present invention comprises an aqueous dispersion of polymeric particles. The aqueous dispersion of polymeric particles may be present in an amount of from 5% to 85%, from 7% to 65%, or from 10% to 50% by dry weight of the aqueous coating composition, on a solid or dry weight basis.

The aqueous coating composition of the present invention may optionally comprise one or more coalescents. By "coalescent" herein is meant a compound capable of assisting the formation of a homogeneous coating film from dispersed polymer particles by lowering the film-forming temperature of the polymer. The molecular weight of the coalescing agent is typically less than 410. Examples of suitable coalescents include ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol hexyl ether, propylene glycol n-butyl ether, dipropylene glycol methylene ether, tripropylene glycol methyl ether, propylene glycol phenyl ether, propylene glycol t-butyl ether, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, 2, 4-trimethyl-1, 3-pentanediol diisobutyrate, or mixtures thereof. Commercially available coalescing agents may include, for example, Texanol ester alcohols, OE-300 and OE-400 coalescing agents, all from Islam chemical, COASOL coalescing agents from Chemyxy International, or mixtures thereof. The amount of coalescent agent in the aqueous coating composition may be less than 5 wt.%, less than 4.5 wt.%, less than 4 wt.%, less than 3.5 wt.%, less than 3 wt.%, less than 2.5 wt.%, less than 2 wt.%, less than 1.8 wt.%, less than 1.5 wt.%, less than 1.2 wt.%, less than 1 wt.%, less than 0.8 wt.%, less than 0.5 wt.%, or even less than 0.1 wt.% based on the dry weight of the aqueous dispersion of polymeric particles. Preferably, the aqueous coating composition is substantially free of coalescents.

The aqueous coating composition of the present invention may also comprise one or more pigments. As used herein, the term "pigment" refers to a particulate inorganic material capable of materially contributing to the opacity or hiding power of a coating. Such materials typically have a refractive index greater than 1.8 and include inorganic pigments and organic pigments. Examples of suitable inorganic pigments include titanium dioxide (TiO)₂) Zinc oxide, zinc sulfide, iron oxide, barium sulfate, barium carbonate, or mixtures thereof. The preferred pigment for use in the present invention is TiO₂。TiO₂It is also available in the form of a concentrated dispersion. The aqueous coating composition may also comprise one or more extenders. The term "extender" refers to a particulate inorganic material having a refractive index of less than or equal to 1.8 and greater than 1.3. Examples of suitable extenders include calcium carbonate, alumina (Al)₂O₃) Clay, calcium sulfate, aluminosilicate, silicate, zeolite, mica, diatom algaeSoil, solid or hollow glass, ceramic beads and opaque polymers such as ROPAQUETM Ultra E (ROPAQUE is a trademark of the dow chemical company) available from the dow chemical company, or mixtures thereof. The Pigment Volume Concentration (PVC) of the aqueous coating composition may be 10% to 75%, 15% to 65%, or 18% to 60%. The PVC of the coating composition can be determined according to the following equation:

the aqueous coating composition of the present invention may comprise one or more matting agents. As used herein, "matting agent" refers to any inorganic or organic particle that provides a matte effect. The matting agent may be selected from silica matting agents, diatomaceous earth, polyurea matting agents, polyacrylates, polyethylene, polytetrafluoroethylene or mixtures thereof. Suitable commercially available matting agents may include, for example, CELITE 499 available from World Minerals Co. Ltd, ACEMATT TS-100 and ACEMATT OK520 silica matting agents available from Woundplast (Evonik), DEUTERON MK polyurea matting agents available from Duterra (Deuteron), micronized wax additives CERAFLOUR 929 and CERAFLOUR 920 available from Bike (BYK), SYLOID silica 7000 matting agents available from Grace Davison; or mixtures thereof. The matting agent can be present in an amount of zero to 10%, 0.1% to 8%, or 0.5% to 5% by weight solids based on the total weight of the aqueous coating composition.

The aqueous coating composition of the present invention may further comprise one or more defoamers. "antifoam" herein refers to a chemical additive that reduces and retards foam formation. The defoamer may be a silicone based defoamer, a mineral oil based defoamer, an ethylene oxide/propylene oxide based defoamer, an alkyl polyacrylate or mixtures thereof. The defoamer can be present in an amount of zero to 2 wt.%, 0.1 wt.% to 1.5 wt.%, or 0.2 wt.% to 1 wt.%, based on the total weight of the aqueous coating composition.

The aqueous coating composition of the present invention may further comprise one or more thickeners (also referred to as "rheology modifiers"). The thickener may include polyvinyl alcohol (PVA), clay materials, acid derivatives, acid copolymers, Urethane Associative Thickeners (UAT), polyether urea polyurethanes (PEUPU), polyether polyurethanes (PEPU), or mixtures thereof. Examples of suitable thickeners include: alkali Swellable Emulsions (ASE), such as sodium or ammonium neutralized acrylic acid polymers; hydrophobically modified alkali swellable emulsions (HASE), such as hydrophobically modified acrylic copolymers; associative thickeners such as hydrophobically modified ethoxylated urethane (HEUR); and cellulosic thickeners such as methyl cellulose ether, hydroxymethyl cellulose (HMC), hydroxyethyl cellulose (HEC), hydrophobically modified hydroxyethyl cellulose (HMHEC), sodium carboxymethyl cellulose (SCMC), sodium carboxymethyl 2-hydroxyethyl cellulose, 2-hydroxypropyl methyl cellulose, 2-hydroxyethyl methyl cellulose, 2-hydroxybutyl methyl cellulose, 2-hydroxyethyl ethyl cellulose and 2-hydroxypropyl cellulose. The preferred thickener is based on HEUR. The thickener may be present in an amount of zero to 4 wt.%, 0.1 wt.% to 3 wt.%, or 0.2 wt.% to 2 wt.%, based on the total weight of the aqueous coating composition.

The aqueous coating composition of the present invention may further comprise water. The concentration of water can be 30 wt.% to 90 wt.%, 35 wt.% to 80 wt.%, or 40 wt.% to 70 wt.%, based on the total weight of the aqueous coating composition.

In addition to the components described above, the aqueous coating composition of the present invention may also comprise any one or combination of the following additives: buffers, neutralizing agents, dispersants, humectants, biocides, antiskinning agents, colorants, flow agents, antioxidants, leveling agents, thixotropic agents, adhesion promoters, anti-scratch additives, and grinding media. These additives may be present in a combined amount of zero to 10 weight percent, 0.1 weight percent to 6 weight percent, or 0.2 weight percent to 4 weight percent, based on the total weight of the aqueous coating composition.

The aqueous coating composition of the present invention can be prepared by techniques known in the coating art. The method of preparing the aqueous coating composition can comprise blending the aqueous dispersion of polymeric particles with other optional components as described above. The components of the aqueous coating composition may be mixed in any order to provide the aqueous coating composition of the present invention. Any of the above optional components may also be added to the composition during or prior to mixing to form an aqueous coating composition.

The aqueous coating composition of the present invention can be applied to a substrate by conventional means including brushing, dipping, rolling and spraying. The aqueous coating composition is preferably applied by spraying. Standard spray techniques and spray equipment can be used such as air atomized spray, air spray, airless spray, high volume low pressure spray, and electrostatic spray (e.g., electrostatic cup application), as well as manual or automated methods. After the aqueous coating composition has been applied to a substrate, the aqueous coating composition can be dried or allowed to dry to form a film (i.e., a coating) at 5 ℃ to 35 ℃ or at an elevated temperature (e.g., 35 ℃ to 90 ℃).

The aqueous coating compositions of the present invention show significantly reduced VOC emissions compared to coating compositions comprising conventional binders and conventional coalescents, and can provide coatings prepared therefrom with improved water bleach resistance without the Koenig hardness compromising film formation, hiding, gloss, and scrub resistance characteristics. The aqueous coating composition of the present invention can be applied and adhered to a variety of substrates. Examples of suitable substrates include concrete, cement substrates, wood, metal, stone, elastomeric substrates, glass, or fabric. The coating composition is suitable for various coating applications, such as architectural coatings, marine and protective coatings, automotive coatings, wood coatings, coil coatings and civil engineering coatings. The aqueous coating composition can be used alone or in combination with other coatings to form a multi-layer coating.

Examples of the invention

Some embodiments of the invention will now be described in the following examples, in which all parts and percentages are by weight unless otherwise indicated.

Methyl Methacrylate (MMA), styrene (St), and 2-ethylhexyl acrylate (EHA) are all available from Shanghai Lang Yuan Chemical Co., Ltd.

Acrylamide (AM) is available from Shanghai Chemicals, Inc. (Shanghai Chemical Reagent Co., Ltd)

Phosphoethyl methacrylate (PEM) is available from suwei.

(n-methacryloyloxyethyl) ethyl ethylene urea (MEU) is available from Suwei.

SYNALOX^TMOA-25 polyalkylene glycol (OA-25), available from Dow Chemical Company (available from The Dow Chemical Company), C having a weight average molecular weight of 750g/mol₄Copolymers of alkyl-terminated butylene oxide and propylene glycol.

UCON^TMOSP-32 polyalkylene glycol (OSP-32), available from the Dow chemical company, is C having a weight average molecular weight of 765g/mol₁₂Copolymers of alkyl-terminated butylene oxide and propylene glycol.

UCON^TMOSP-46 polyalkylene glycol (OSP-46), available from the Dow chemical company, is C having a weight average molecular weight of 950g/mol₁₂Copolymers of alkyl-terminated butylene oxide and propylene glycol.

UCON^TMOSP-150 polyalkylene glycol (OSP-150), available from the Dow chemical company, is C having a weight average molecular weight of 1,850g/mol₁₂Copolymers of alkyl-terminated butylene oxide and propylene glycol.

DISPONIL Fes-32 surfactant ("Fes-32") is available from Cognis (Corning Inc.) as the sodium salt of fatty alcohol ether sulfate (31% solids).

Ammonium Persulfate (APS) (solids: 97%) as initiator, t-butyl hydroperoxide (t-BHP) (solids: 70%) as chaser catalyst, and erythorbic acid (IAA) as chaser activator are all available from Shanghai Chemicals, Inc.

NATROSOL 250HBR (250HBR), available from Ashland Aqualon Company, is a rheology modifier.

TERGITOL^TMEF-406 (70%), available from the Dow chemical company, is a nonionic surfactant.

OROTAN^TM1288 dispersant (45%), commercially available from Dow chemical company, is a polymethacrylate-type dispersant.

Rhodoline FT-100 (100%), available from Suwei, is an additive for water-based paints to improve freeze-thaw stability.

Noploc NXZ antifoam is commercially available from noploc (Nopco).

Ti-Pure R-706, available from The Chemours Company, is titanium dioxide (TiO)₂)

Celite 499, available from Imerys Company, is a diatomaceous earth used as a matting agent.

CC-700, available from Guangfu Building Materials Fine Chemicals Industry Co, Ltd., is calcium carbonate.

ASP 170, available from BASF, is a hydrated aluminum silicate.

DB-80, available from Bright Industrial Co.Ltd, is calcined clay.

Optifilm Enhancer 400(OE-400) coalescing agents are available from Istman chemical company.

Texanol ester alcohol, available from Istmann chemical, was trimethylpentanediol isobutyrate.

ROPAQUE ultra-E opaque polymers (ultra polymers) are available from the dow chemical company.

ACRYSOL^TMTT-935 (50%), available from the Dow chemical company, is a hydrophobically modified alkali swellable emulsion (HASE) thickener.

KATHON^TMLXE biocides are available from dow chemical company.

SYNALOX, UCON, TERGITOL, ACRYSOL, OROTAN, and KATHON are trademarks of the Dow chemical company.

The following standard analytical equipment and methods were used in the examples.

GPC analysis

The molecular weight of the sample (e.g., polyalkylene glycol) was determined by GPC. GPC analysis was calibrated using a mixture of polyols (1.5 wt% in Tetrahydrofuran (THF)) and the calibrated molecular weights Mw were based on a broad standard method. By adding 15 mg of VORANOL to 1g of THF^TMCP6001, VORANOL CP4100, VORANOL P2000 and VORANOLCP1000 (all available from Dow chemical Co., Ltd.) obtained a polyol mixture. (VORANOL is a trademark of Dow chemical Co., Ltd.)

150 + -20 mg of sample was weighed into a 20mL vial, followed by the addition of 10mL THF (HPLC grade, LabScan). The vial was sealed with a butyl rubber septum and shaken. The following table gives the instrument conditions:

minimum film formation temperature test

The MFFT was determined using Rhopoint MFFT Bar-90 and bars with gradient temperature in the range of 0 ℃ to 60 ℃. A tape was placed on the strip and the aqueous dispersion to be tested was then pulled down onto the tape to form a 75 μm wet film. After 2 hours, the tape was pulled manually off the strip to observe mechanical failure of the film. The lowest temperature at which the film was discontinuous was recorded as MFFT.

Measured glass transition temperature (Tg)

The measured Tg was determined by DSC. 5-10mg of the sample was analyzed in sealed aluminum pans under a nitrogen atmosphere on a TA Instrument DSC Q2000 equipped with an autosampler. Tg measurements by DSC had three cycles including-60 ℃ to 150 ℃,10 ℃/min (cycle 1, then held for 5 minutes to eliminate the thermal history of the sample); 150 ℃ to-60 ℃,10 ℃/min (cycle 2) and-60 ℃ to 150 ℃,10 ℃/min (cycle 3). Tg was obtained from cycle 3 by the "half-high" method.

Tolerance to water bleaching

Samples of the coating composition to be tested were first prepared and left at room temperature for 12 hours. Each sample was pulled down on a vinyl card having a wet thickness of 100 μm and then cured at room temperature for 12 hours. The coated vinyl card was immersed in distilled water for seven days, and then the color change of the coating film on the vinyl card was visually observed. The water bleach resistance performance of the coating film was scored according to the whiteness of the clear film as follows,

score of	Appearance of the product
		5	Without bleaching
4	One point bleaching
		3	Slightly bleaching
2	Partial bleaching
		1	Complete bleaching

Koenig hardness

Coated panels were prepared by applying the test coating composition onto Q panels (cold rolled steel) using a 100 μm applicator. The coated panels were then allowed to dry at 23 ℃ and RH 50% for 1 hour. Pendulum (Koenig) hardness was tested according to ASTM D4366-95 (amplitude limit: 6 to 3 ℃ and period of oscillation: 1.4 seconds) and reported in seconds.

Contrast ratio (C.R.)

Contrast is a measure of hiding power, which correlates well with the visual impression of hiding power. The contrast was tested according to the following procedure:

the paint formulation was cast onto white black cards (5C opacity cards) with a 100 μm film applicator and allowed to dry for 1 day. The Y-reflectance values of the three regions were measured in the white and black regions of the 5C opacity card, respectively. The contrast is reported as the average reflectance on black/the average reflectance on white.

Degree of gloss

The paint formulation was cast onto white black cards (5C opacity cards) with a 100 μm film applicator and allowed to dry for 1 day. The cards were then separately tested for 20/60/85 degree gloss on the white portion of the card using a micro-TRI gloss meter by BYK Gardner.

Scrub resistance

Scrub resistance is measured according to ASTM test method D2486-74A (2006). The paint formulation was coated on a black vinyl scrub card (model P-121-10N, Leneta corporation) with a 7 mil (175 μm) film machine and then air dried in a horizontal position in a thermostatic chamber (CTR, 23 ± 2 ℃ and 50 ± 5% relative humidity) for 7 days. Scrub tests were performed on a gloss maker (Sheen machine) model REF903 equipped with a metal tray and nylon bristles. The brush was soaked in water overnight prior to use and then placed in a holder with the bristle side of the brush facing down to start the test. Ten grams of abrasive scouring media (model SC-2, Leneta corporation) was applied to the brush surface. The number of cycles required to completely remove the coating film on one continuous line was recorded. The number of cycles for a coating composition comprising OE-400 as a coalescent (comparative paints a-I) was recorded as 100%, and the number of cycles for the other examples was a relative percentage value compared to the comparative paints a-I. A relative percentage higher than 95% means an acceptable scrub resistance. A higher relative percentage means better scrub resistance.

Contamination resistance

To test for stain resistance, the test paint formulations were coated on a Leneta P-121-10N black vinyl card with a wet film thickness of 7 mils (175 μm). The resulting coating film was dried in a thermostatic chamber (CTR, 25 ℃, 50% relative humidity) for 7 days. Then, different stains including marker pens, pencils, crayons, green tea, yellow tea, coffee, vinegar and blue ink were applied to the surface of the paint film, respectively, so that the stains were immersed in the film for 3 hours. The soil release tests were performed on a modified scrubbing machine equipped with a boat containing 3M commercial sponge saturated with 1% household detergent solution. A 1 Kg weight was placed on the boat to ensure that all samples were tested under the same pressure. Each sample was washed for 200 cycles using the 3M sponge described above. The sample cards were rinsed with water before being rated for stain resistance and then completely dried at room temperature. The stain resistance score for each stain was evaluated on a scale of 1 to 10 by visually rating the percent stain removed by comparison to the non-scrubbed side based on the criteria described in the table below. The stain resistance of the paint film was then reported as the sum of each stain resistance score. The higher the sum of each anti-contamination score, the better the anti-contamination.

Stain resistance rating Scale for Each stain

Anti-contamination rating	Stain removal
		10	No stain or mark left: (<1％)
9	Remove 90% to 99% of the stain
		8	Remove 80% to 89% of the stain
7	70% to 79% of the stain was removed
		6	60% to 69% of the stain was removed
5	Removing 50% to 59% of the stain
		4	Removing 40% to 49% of the stain
3	Removing 20% to 39% of the stain
		2	Removing 2% to 20% of the stain or leaving a noticeable stain
1	Almost no stain (<1%) is removed

VOC emission test

(1) Reaction chamber testing method for emission test

A60L reaction chamber (V-60 from Simplewell Technology) was used for VOC emission testing. The reaction chamber conditions were as follows: temperature: 23 +/-2 ℃; humidity: 50% +/-10%; pressure: 10-20Pa higher than the standard atmospheric pressure; and the air exchange rate: 0.5 hour^-1.16 g of the paint formulation was applied to 25cm x 25cm glass, which was then placed in the reaction chamber. The flow rate at the outlet of the reaction chamber was 500 ml/min. At the predetermined sampling point, a Tenax TA cartridge (60/80, glass tube, Gerstel) was used and the sampling time was 30 minutes (flow rate: 200 ml/min, precision measured using a flow meter). The total volume collected by the Tenax collection cartridge was 6L. The Tenax TA cartridge was then immediately analyzed with a TDS GC-MS instrument for VOC studies. The TDS GC-MS instrument conditions were as follows:

(2) TDS-GC-MS parameters

A Gerstel thermal desorption system with a TDS autosampler was used in conjunction with Agilent GC 7890-MSD 5975C.

And (3) GC column: RXI-5MS column (30m × 0.25mm, 0.5 μm membrane); carrier gas: helium carrier gas at a constant flow of 1.0 ml/min; and GC oven procedure: 50 ℃ for 10 minutes, 5 ℃/min ramp to 250 ℃ for 5 minutes.

TDS parameters: cryofocusing was performed using a Gerstel cold injection system 4(CIS-4) with a Programmable Temperature Vaporization (PTV) injector prior to transferring the analytes to the analytical GC column. The temperature of the TDS was 20 ℃ (hold for 1 minute) at 60 ℃/minute to 280 ℃ (hold for 15 minutes). The CIS-4 programming was from-150 deg.C (equilibration time: 1 minute) at 12 deg.C/s to 280 deg.C (hold 5 minutes). The temperature of the GC-MS transmission line was 280 ℃. Mass Spectrometry Detector (MSD) parameters (scan mode): MS source temperature: 230 ℃, MS quadrupole temperature: 150 ℃, collection mode: scanning, and the mass is 29-370 Da.

¹H NMR analysis

For each aqueous dispersion to be tested, 15ml of hexane was added to a 5g sample of the dispersion. The resulting mixture was shaken overnight. The hexane phase is then separated off and passed through N₂And (5) blowing and drying. The residue of the dried hexane phase was sent for NMR analysis. To carry out¹H NMR measurements were taken to quantify the amount of polyalkylene oxide (PAO) in the extracted hexane phase and reported as the value of the extracted PAO in weight percent based on the total amount of PAO in the aqueous dispersion. The percentage of PAO content in the polymeric particles of the aqueous dispersion was then calculated by subtracting the extracted PAO value from 100%. Triphenylphosphine (PPh3) was chosen as internal standard. A mixture of 21.2mg of PPh3 and 31.47mg of OA-25 was used as a standard sample for comparing example C and example 1 dispersions in Table 2. A mixture of 32.9mg of PPh3 and 25.8mg of OSP-32 was used as a standard sample to compare the dispersions of example F and example 2 in Table 2. A mixture of 24.7mg of PPh3 and 26.8mg of OSP-46 was used as a standard sample to compare the dispersions of example G and example 3 in Table 2. acetone-D6 was used as the solvent.

Comparative example A

First, a monomer mixture was prepared by mixing 424.11g of Deionized (DI) water, 45.08g of FES-32 surfactant (31%), 373.74g of MMA, 561.50g of EHA, 602.37g of St, 45.88g of AM, 23.81g of PEM, and 17.56g of MEU.

An initial charge of 876.26g of DI water was added to a 1 gallon container equipped with a reflux condenser, addition funnel, and stirrer with agitation at 130 rpm. The reaction vessel was heated to 85 ℃. 7.19g FES-32 surfactant (31%) was added to the vessel. A reaction vessel was charged with 98.00g of the monomer mixture and an initial catalyst solution (6.40g of APS in 17.53g of DI water). The reaction mixture was used for seed formation at 82-88 ℃ for 5 minutes. The remaining monomer mixture, catalyst (3.36g of APS in 101.65g of DI water) was then added over a period of 150 minutes at a temperature between 84 ℃ and 86 ℃. After the addition of the monomer mixture and catalyst was complete, the contents of the reaction vessel were cooled to room temperature. During cooling, a mixture of 1.63g of t-BHP in 21.91g of DI water and 0.86g of IAA in 21.91g of DI water was added while the temperature was at 65 ℃. When the vessel temperature reached 50 ℃ or less, 21.73g of aqueous ammonia (25% aqueous solution) was added to adjust the pH of the obtained dispersion to 7 or more to obtain an aqueous dispersion. The resulting dispersion contained polymeric particles having the following composition, based on the total weight of the monomers: 23.47 wt.% MMA/35.16 wt.% EHA/37.76 wt.% ST/1.00 wt.% AM/1.50 wt.% PEM/1.11 wt.% MEU.

Comparative example B

Comparative example B was prepared according to the same procedure as described above in preparing comparative example a dispersion, except 174.78g of OSP-150 was added to the monomer mixture. The resulting dispersion contained polymeric particles having the following composition, based on the total weight of the monomers: 23.47 wt.% MMA/35.16 wt.% EHA/37.76 wt.% ST/1.00 wt.% AM/1.50 wt.% PEM/1.11 wt.% MEU//11.00 wt.% OSP-150.

Comparative example C

OA-25 in an amount of 11 wt% was added to the comparative example a dispersion based on the solid weight of the comparative example a binder and stirred at room temperature for 30 minutes. A portion of OA-25 was immediately observed to exude to the surface (i.e., oily droplets of OA-25 floated on the surface). The resulting blend compositions were evaluated for MFFT.

Comparative example D

Comparative example a dispersion was mixed with 11 wt.% OE-400 based on the solid weight of the comparative example a dispersion and stirred at room temperature for 30 minutes. The resulting blend compositions were evaluated for MFFT.

Comparative example E

Comparative example a dispersion was mixed with 11 wt% Texanol based on the solid weight of the comparative example a dispersion and stirred at room temperature for 30 minutes. The resulting blend compositions were evaluated for MFFT.

Comparative example F

OSP-32(250mg) was added to 5g of the comparative example A dispersion and stirred at room temperature for 30 minutes.

Comparative example G

OSP-46(250mg) was added to 5g of the comparative example A dispersion and stirred at room temperature for 1 hour.

Example 1

Example 1 was prepared according to the same procedure as described above in preparing comparative example B dispersion, except OSP-150 used in comparative example B was replaced with OA-25. The resulting dispersion contained polymeric particles having the following composition, based on the total weight of the monomers: 23.47 wt.% MMA/35.16 wt.% EHA/37.76 wt.% ST/1.00 wt.% AM/1.50 wt.% PEM/1.11 wt.% MEU//11.00 wt.% OA-25.

Example 2

Example 2 was prepared according to the same procedure as described above in preparing comparative example B dispersion, except OSP-150 used in comparative example B was replaced with OSP-32. The resulting dispersion contained polymeric particles having the following composition, based on the total weight of the monomers: 23.47 wt.% MMA/35.16 wt.% EHA/37.76 wt.% ST/1.00 wt.% AM/1.50 wt.% PEM/1.11 wt.% MEU//11.00 wt.% OSP-32.

Example 3

Example 3 was prepared according to the same procedure as described above in preparing comparative example B dispersion, except OSP-150 used in comparative example B was replaced with OSP-46. The resulting dispersion contained polymeric particles having the following composition, based on the total weight of the monomers: 23.47 wt.% MMA/35.16 wt.% EHA/37.76 wt.% ST/1.00 wt.% AM/1.50 wt.% PEM/1.11 wt.% MEU//11.00 wt.% OSP-46.

The properties of the resulting dispersion are shown in tables 1 and 2.

Table 1.Physical Properties of the aqueous Dispersion

Aqueous dispersion	Measured Tg,. deg.C	pH	Particle size, nm	Solids content%	Viscosity, cps
						Comparative example A	26.3	8.43	106	47.5	504
Comparative example B	7.8	8.43	112	48.8	382
						Example 1	4.7	7.96	116	48.5	786
Example 2	4.4	8.63	121	48.6	602
						Example 3	5.6	8.67	108	48.7	430

Table 2 gives the amounts of PAO in the dispersions obtained by the cold blending process and the polymerization process, respectively¹H NMR analysis results. Extracted PAO means PAO present in the aqueous medium of the aqueous dispersion.

Table 2.Polyalkylene oxides in aqueous dispersions

By weight, based on the total weight of PAO in the aqueous dispersion.

The above dispersions were divided into two groups, group I and group II, and evaluated for film-forming characteristics.

The group I dispersions were evaluated and the results are shown in table 3. As shown in table 3, comparative example a dispersion alone provided a MFFT of about 27.2 ℃, and the films formed therefrom showed severe cracking. When OA-25 was cold blended into comparative example a, many oily droplets were observed to float on the surface, indicating that cold blending is not an effective method to make a uniform and stable binder or paint system. Further, the comparative example C compositions formed by cold blending comparative example a dispersion with OA-25 at the same loading had a higher MFFT than those made by blending comparative example a dispersion with Texanol ester alcohol or OE-400 (comparative examples D and E). In contrast, when OA-25 was added during the polymerization process to prepare the dispersion, the resulting dispersion of example 1 was homogeneous and very stable and produced a much lower MFFT than comparative example C, indicating that the in-process addition of OA-25 was more effective at reducing the MFFT than cold blending of OA-25 with the comparative example a dispersion.

Table 3.Composition and Properties of group I Dispersion

Group I samples	Appearance of Dispersion	Dispersion MFFT/. degree.C
			Comparative example A	Homogeneous stable emulsions	27.2
Example 1	Homogeneous stable emulsions	6.1
			Comparative example C	Oily liquid droplets floating on the surface	13.8
Comparative example D	Homogeneous stable emulsions	6.2
			Comparative example E	Homogeneous stable emulsions	10.6

The group II dispersion was investigated to determine the effect of different types of polyalkylene oxides on film forming characteristics and the results are given in table 4. The appearance of the resulting film was visually observed with the naked eye. Both example 1 and 2 dispersions formed uniform and continuous films at room temperature. Example 3 the dispersion also formed a continuous film at room temperature. In contrast, the comparative example B dispersion failed to form a continuous film (many cracks were observed). In this round of testing, the example 1 dispersion was considered a control to calibrate the performance of other dispersions with different polyalkylene oxides. The results show that the comparative example B dispersion shows a higher MFFT and undesirable film-forming properties compared to the Exs 1-3 dispersion.

TABLE 4 Properties of the group II dispersions

As the tests performed in table 3, the MFFT was tested for the presence of a 5 ℃ variation using different equipment.

Clear coating composition

Clear coating compositions, clear coating 2, clear coating 4 and clear coating 5, were prepared by mixing different binders with thickeners with or without coalescents, based on the formulations given in table 5. The day 1 and day 9 Koenig hardness and water resistance characteristics of clear films made from these coating compositions were measured according to the test methods described above. As shown in table 5, the coating composition containing Texanol ester alcohol exhibited the highest Koenig hardness, which further increased after 9 days of aging due to evaporation of Texanol ester alcohol (clear coating # 2). The composition comprising the dispersion of example 1 showed significantly higher Koenig hardness than the composition comprising comparative example a and OE-400 (clear coat #4), which did not increase over time indicating that little coalescent evaporated. Thus, the composition comprising the dispersion of example 1 showed an advantage over the composition comprising OE-400 in terms of Koenig hardness. The results also show that the compositions comprising the dispersion of example 1 without added coalescent exhibit much better water bleach resistance than the compositions comprising the comparative example a as binder Texanol ester alcohol and OE-400 as coalescent, respectively.

TABLE 5 clear coating composition and Properties

Sample numbering	Clear coating #2	Clear coating #4	Clear coating #5
				Type of adhesive	Example 1 Dispersion	Comparative example A Dispersion	Comparative example A Dispersion
Weight of Binder/g	100	95.04	95.04
				Type of coalescing agent	0	OE-400	Texanol
Weight of coalescent agent/g	0	4.97	4.97
				Thickener type	RM-8W	RM-8W	RM-8W
Weight of thickener/g	0.3	0.3	0.3
				Characteristics of
Day 1 Koenig hardness/sec	13	7	16
				Day 9 Koenig hardness/sec	13	7	22
Tolerance to water bleaching	3	1	1

Paint formulations

Paint formulations for Comp paint a-I, Comp paint a-II and paint-1 were prepared based on the formulations given in table 6. The paint formulation is prepared by a two-step process. First, the ingredients of the milling stage were mixed for 2-4 hours at high speed dispersion (2,000rpm) to obtain a well dispersed slurry. The ingredients of the letdown stage are then added to the slurry. The properties of the resulting paint formulations were evaluated according to the test methods described above, and the results are given in table 6.

For the paint formulations of Comp paints a-I and Comp paints a-II, the non-volatile OE-400 coalescent and the commonly used high VOC coalescent Texanol and comparative example a dispersion, respectively, were used to aid film formation. Paint-1, which contained the example 1 dispersion without coalescent, exhibited good film-forming characteristics as indicated by the formation of a uniform and continuous film.

TABLE 6 paint formulations

To evaluate the VOC contribution of the example 1 dispersion to the paint formulation, emission tests were also performed on the paint formulation described above. The results are given in table 7. Paint-1 containing the OA-25 dispersion of example 1 released less VOC than the paint formulation containing OE-400 (Comp paint a-I), indicating that the example 1 dispersion is more environmentally friendly than OE-400 for application in water-based coatings. Other properties of these paint formulations were also measured and the results are given in table 7. Paint-1 shows comparable contrast, whiteness, gloss, scrub resistance and stain resistance properties compared to paints containing Texanol ester alcohol or OE-400 (Comp paints A-I and Comp paints A-II).

TABLE 7 Properties of paints with different plasticizers/coalescents