WO2014139074A1

WO2014139074A1 - Binder composition and its application in anti-dewing coating composition

Info

Publication number: WO2014139074A1
Application number: PCT/CN2013/072398
Authority: WO
Inventors: Qingwei Zhang; Longlan Cui; Tingke Zhang; Caifeng WANG
Original assignee: Dow Global Technologies Llc; Rohm And Haas Company
Priority date: 2013-03-11
Filing date: 2013-03-11
Publication date: 2014-09-18
Also published as: CN105026505A; KR102087740B1; KR20150126826A; CN105026505B

Abstract

A binder composition for below critical pigment volume concentration coating is provided. The binder composition comprises: a) from 10% to 80% by wet weight based on the total wet weight of the binder composition, at least one aqueous emulsion polymer, and b) from 2% to 10% by dry weight based on the total dry weight of the binder composition, a second polymer comprising sodium styrene sulfonate, 2-acrylamide-2-methylpropanesulfonic acid or the combination thereof; wherein the molecular weight of the second polymer is from 10,000 to 70,000. An aqueous coating composition comprises the binder composition with improved liquid stain repellency.

Description

BINDER COMPOSITION AND ITS APPLICATION IN ANTI-DEWING COATING

COMPOSITION

Field

This invention relates to a coating composition. Especially, it relates to an aqueous coating composition with improved liquid stain repellency.

Background

In architectural coating applications, dew formation, also known as dewing, occurs under conditions of high humidity and high temperature or at interfacial boundaries where there is a large temperature and humidity difference. Dew leaves drying marks on the wall and adversely affects its appearance. Dew may also lead to the growth of microbes which often are harmful to human health. These issues caused by dewing are more conspicuous in below critical pigment volume concentration (CPVC) coatings according to CN 102072921 A to GU Jian-yong et al.

Porous pigments have been used to make anti-dewing coatings. Japanese patent No. JP 02552859B2 to Ishida Yoshiichi et al. disclosed a covering composition which incorporates porous inorganic powder calcium silicate crystals into a synthetic resin emulsion and which reduces dewing. However, porous pigments adversely impact coating performances such as scrub resistance, elasticity and dry time.

Another commonly used method to reduce dewing is to use surfactants. Irusta et al, Journal of Applied Polymer Sciences Vol. Ill, 2299 (2009), compared the effectiveness of two anti-dewing additives - fatty acid glycerol monoesters and N-stearyl diethanol amine fatty acid monoesters - in different compositions of low density polyethylene (LDPE) and ethylene/ vinyl acetate (EVA) copolymer films. However, those low molecular weight surfactants adversely impact the water resistance of the coating films.

Thus, it is desirable to provide a hydrophilic polymer which, upon addition to base polymers, renders a coating with enhanced dewing resistance without compromising other aspects of coating performance.

Summary

The present invention provides a binder composition for below critical pigment volume concentration coating comprising: a) from 10% to 80% by wet weight based on the total wet weight of the binder composition, at least one aqueous emulsion polymer; and b) from 2% to 10% by dry weight based on the total dry weight of the binder composition, a second polymer comprising sodium styrene sulfonate, 2-acrylamide-2- methylpropanesulfonic acid or the combination thereof; wherein the molecular weight of the second polymer is from 10,000 to 70,000.

The present invention further provides a coating composition comprising the binder composition.

Detailed Description

For the purpose of describing the components in the compositions of the present invention, all phrases comprising parenthesis denote either or both of the included parenthetical matter and its absence. For example, the phrase "(co)polymer" includes, in the alternative, polymer, copolymer and mixtures thereof; the phrase "(meth)acrylate" means acrylate, methacrylate, and mixtures thereof.

As used herein, the term "polymer" shall include homopolymers and copolymers.

As used herein, the term "acrylic" shall mean (meth)acrylic acid, (meth)alkyl acrylate, (meth)acrylamide, (meth)acrylonitrile and modified forms thereof such as (meth)hydroxyalkyl acrylate.

As used herein, the term "aqueous" shall mean water or water mixed with 50 wt% or less, based on the weight of the mixture, of water-miscible solvent.

As used herein, the term "pigment volume concentration (PVC)" is the volume percentage of pigment in the dry paint film. The critical pigment volume concentration (CPVC) is understood as the pigment volume concentration where there is just sufficient binder to provide a completely adsorbed layer of binder on the pigment surfaces and to fill all the interstices between the particles in a close-packed system.

The CPVC can be determined by wetting out dry pigment with just sufficient linseed oil to form a coherent mass. This method yields a value known as the "oil absorption" (OA). It indicates the amount of oil required to wet out 100 grams of dry pigment. The method for determining the OA is described in British Standard 3483 (BS3483). The CPVC can be calculated from the OA by the following formula:

CPVC = 100% / (1 + (density_pi_gme„t / density_resin)) x (OA / 100).

If a mixture of pigments or resins having different densities is used, the respective average density of the pigment or resin mixture has to be used for the calculation. For determination of the CPVC of specific coating compositions, it is preferred to carry out the process described in BS3483 with the resin or mixture of resins used in the coating composition, rather than with linseed oil.

The present invention is particularly applicable in below critical pigment volume concentration coatings.

The binder composition of the present invention comprises from 10% to 80%, preferably from 20%> to 60%>, and more preferably from 30%> to 50%>, by wet weight based on the total wet weight of the binder composition, at least one aqueous emulsion polymer.

The aqueous emulsion polymer is copolymerized from ethylenically unsaturated nonionic monomers. Herein "nonionic monomer" means that the copolymerized monomer residue does not bear an ionic charge between pH=l-14. The ethylenically unsaturated nonionic monomers used in this invention include, for example, (meth)acrylic ester monomers, where (meth)acrylic ester designates methacrylic ester or acrylic ester, including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydro xyethyl methacrylate, hydro xypropyl methacrylate; (meth)acrylonitrile; (meth)acrylamide; amino -functional and ureido-functional monomers; monomers bearing acetoacetate functional groups; styrene and substituted styrenes; butadiene; ethylene, propylene, a -olefins such as 1-decene; vinyl acetate, vinyl butyrate, vinyl versatate and other vinyl esters; and vinyl monomers such as vinyl chloride, vinylidene chloride.

The aqueous emulsion polymer of the present invention further comprises up to 10%>, preferably up to 5%, more preferably up to 2.5%, by weight based on the dry weight of the polymer, of an ethylenically unsaturated monomer carrying at least one functional group selected from carboxyl, carboxylic anhydride, hydroxyl, amide, sulphonate, phosphonate and mixtures thereof. Examples of these types of monomers are ethylenically unsaturated carboxylic or dicarboxylic acids, especially acrylic or methacrylic acid, itaconic acid, maleic acid, or the amides, especially N-alkylolamides or hydroxyalkyl esters of the above- mentioned carboxylic acids, such as (meth)acrylamide, N-methylol(meth)acrylamide, 2- hydroxyethyl(meth) acrylamide, hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate. More preferably, the functional monomer is methyl acrylic acid, acrylic acid, acrylamide, methacrylamide. Most preferably, the functional monomer is methyl acrylic acid.

Optionally, the aqueous emulsion polymer may further comprise, as copolymerized units, from 0 to 0.5wt%>, preferably from 0.05%> to 0.4%>, more preferably from 0.1%> to 0.3%>, by weight based on the total weight of the polymer, at least one ethylenically unsaturated monomer having at least one alkoxysilane functionality. Preferably it is a hydrolyzable alkoxysilane functionality. The alkoxysilane functionalized monomer includes, for example, vinyltrialkoxysilanes such as vinyltrimethoxysilane; alkylvinyldialkoxysilanes; (meth)acryloxyalkyltrialkoxy-silanes; such as (meth)acryloxyethyltrimethoxysilane and (meth)acryloxypropyl-trimethoxysilane; and the derivatives thereof.

The binder composition of the present invention further comprises from 2 wt.% to 10 wt.%, preferably from 3% to 10%, and more preferably from 5%> to 10%>, by dry weight based on the total dry weight of the binder composition, a second polymer comprising sodium styrene sulfonate, 2-acrylamide-2-methylpropanesulfonic acid or the combination thereof.

Suitable second polymers include, but are not limited to, poly(sodium 4-styrene- sulfonate) as commercially purchased from Sigma-Aldrich Co. LLC; poly( sodium 2-styrene- sulfonate), poly(sodium 3-styrene-sulfonate), poly(2-acrylamide-2-methylpropanesulfonic acid), poly(sodium 4-styrene-sulfonate-co-2-acrylamide-2-methylpropanesulfonic acid), poly(sodium 2-styrene-sulfonate-co-2-acrylamide-2-methylpropanesulfonic acid), and poly(sodium 3-styrene-sulfonate-co-2-acrylamide-2-methylpropanesulfonic acid).

In the embodiments of the present invention, the molecular weight of the second polymer comprising sodium styrene sulfonate, 2-acrylamide-2-methylpropanesulfonic acid or the combination thereof is from 10,000 to 70,000. In a preferred embodiment, the molecular weight of the second polymer is from 1 1 ,000 to 25,000. Most preferably, it is from 13,000 to 20,000.

In one particular embodiment of the present invention, the second polymer is a sodium styrene sulfonate homopolymer or its copolymer with other ethylenically unsaturated nonionic monomers. In this embodiment, the sodium styrene sulfonate is in the content range of from 80% to 100%, preferably from 90% to 100%, and most preferably from 95% to 100%), by dry weight based on the total dry weight of the second polymer comprising sodium styrene sulfonate. It is preferable that the second polymer is a homopolymer of sodium styrene sulfonate.

In another embodiment of the present invention, the second polymer is a 2- acrylamide-2-methylpropanesulfonic acid homopolymer or its copolymer with other ethylenically unsaturated nonionic monomers. In this embodiment, the 2-acrylamide-2- methylpropanesulfonic acid is in the content range of from 80% to 100%, preferably from 90%) to 100%), and most preferably from 95%> to 100%), by dry weight based on the total dry weight of the second polymer. It is preferable that the second polymer is a 2-acrylamide-2- methylpropanesulfonic acid homopolymer.

In yet another embodiment of the present invention, the second polymer is a copolymer of sodium styrene sulfonate and 2-acrylamide-2-methylpropanesulfonic acid or the copolymer with other ethylenically unsaturated nonionic monomers. In this embodiment, the weight ratio of sodium styrene sulfonate to 2-acrylamide-2- methylpropanesulfonic acid in this copolymer is from 1 :99 to 99: 1, and the total weight of sodium styrene sulfonate and 2-acrylamide-2-methylpropanesulfonic acid is from 80% to 100%, preferably from 90% to 100%, and most preferably from 95% to 100%, by weight based on the total weight of the second polymer.

Optionally, the second polymer of the present invention may further comprise from 0.1% to 20%, preferably from 0.1% to 10%, and most preferably from 0.1% to 5% by weight based on the total weight of the second polymer, an acetoacetoxyethyl methacrylate (AAEM), a diacetone acrylamide (DAAM), or mixtures thereof.

The polymerization techniques used to prepare the copolymer are well known in the art, for example emulsion polymerization. In the emulsion polymerization process, conventional surfactants include anionic and nonionic surfactants, and illustrative examples include, but are not limited to alkali metal or ammonium salts of alkyl, aryl, or alkylaryl sulfates, sulfonates or phosphates; alkyl sulfonic acids; sulfo succinate salts; fatty acids; ethylenically unsaturated surfactant monomers; and ethoxylated alcohols or phenols. The amount of surfactant used is usually 0.1% to 6%> by weight, based on the weight of monomer. Either thermal or redox initiation processes may be used. The reaction temperature is maintained at lower than 100 °C throughout the course of the reaction. The reaction temperature is preferably between 30 °C and 95 °C, more preferably between 50 °C and 90 °C. The monomer mixture may be added neat or as an emulsion in water. The monomer mixture may be added in one or more additions or continuously, linearly or not, over the reaction period, or combinations thereof.

Conventional free radical initiators may be used such as, hydrogen peroxide, sodium peroxide, potassium peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium and/or alkali metal persulfates, sodium perborate, perphosphoric acid and salts thereof, potassium permanganate, and ammonium or alkali metal salts of peroxydisulfuric acid, typically at a level of 0.01% to 3.0% by weight, based on the weight of total monomer. Redox systems using the same initiators coupled with a suitable reductant such as, sodium sulfoxylate formaldehyde, ascorbic acid, isoascorbic acid (IAA), alkali metal and ammonium salts of sulfur-containing acids, such as sodium sulfite, bisulfite, thiosulfate, hydrosulfite, sulfide, hydrosulfide or dithionite, formadinesulfmic acid, hydroxymethanesulfonic acid, acetone bisulfite, amines such as ethanolamine, glycolic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid and salts of the preceding acids may be used. Redox reaction catalyzing metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium, or cobalt may be used. Chelating agents for the metals may optionally be used.

Buffer is optionally used in the present invention. It is a kind of salt and used to control the in process pH value during a polymerization reaction. General buffer salts include phosphates, citrates, acetates bicarbonate and carbonates. The counter ion may be sodium, potassium, and ammonium ion. Buffer may be added in one or more additions or continuously, linearly or not, over most or all of the entire reaction period or during limited portion(s) of the reaction period, or combinations thereof. The in process pH value may be controlled using buffer at between 2 to 7, preferably at between 2 to 5, more preferably at between 2 to 4.

Chain transfer agents including, but not limited to, halogen compounds such as tetrabromomethane, allyl compounds, or mercaptans such as alkyl thioglycolates, alkyl mercaptoalkanoates, and C4-C22 linear or branched alkyl mercaptans, may be used to lower the molecular weight of the emulsion polymer and/or to provide a different molecular weight distribution than would otherwise have been obtained with any free-radical-generating initiator(s). Chain transfer agent(s) may be added in one or more additions or continuously, linearly or not, over most or all of the entire reaction period or during limited portion(s) of the reaction period such as in the kettle charge and in the reduction of residual monomer stage. Chain transfer agents are typically used in the amount of from 0 to 5 wt%, based on the total weight of monomer used to form the aqueous copolymer dispersion. A preferred level of chain transfer agent is from 0.01 to 0.5 mole%, more preferably from 0.02 to 0.4 mole% and most preferably from 0.05 to 0.2 mole%, based on the total number of moles of monomer used to form the aqueous copolymer dispersion.

In the embodiment where DAAM is comprised in the second polymer, the binder composition of the present invention further comprises from 0.1% to 20%, preferably from 0.5%) to 10%), and most preferably from 1% to 5% by weight based on the total weight of the binder composition, an adipic dihydrazide (ADH). The binder composition of the present invention may further comprise from 0.005% to 0.3%), preferably from 0.05%> to 0.2%> by weight based on the total weight of the binder composition, a ZnO.

The binder composition of the present invention is made of a stable coating composition in one of its applications.

The coating composition of the present invention may further comprise at least one conventional coating additives including, but not limited to, coalescing agents, cosolvents, surfactants, buffers, neutralizers, thickeners, non-thickening rheology modifiers, dispersants, humectants, wetting agents, mildewcides, biocides, plasticizers, antifoaming agents, defoaming agents, anti-skinning agents, flowing agents, crosslinkers, and anti-oxidants.

Thickeners being used herein include, but are not limited to polyvinyl alcohol (PVA), hydrophobically modified alkali soluble emulsions (HASE), alkali- soluble or alkali swellable emulsions (ASE), hydrophobically modified ethylene oxide-urethane polymers known in the art as HEUR, cellulosic thickeners such as hydroxymethyl cellulose (HMC), hydroxyethyl cellulose (HEC), hydrophobically-modified hydroxy ethyl 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-hydoxypropyl cellulose. Also useful as thickeners are fumed silica, attapulgite clay and other types of clay, and titanate chelating agents.

Dispersants being used herein include non-ionic, anionic and cationic dispersants such as polyacid with suitable molecular weight, 2-amino-2-methyl-l-propanol (AMP), dimethyl amino ethanol (DMAE), potassium tripolyphosphate (KTPP), trisodium polyphosphate (TSPP), citric acid and other carboxylic acids. Prefer dispersants are the polyacids with suitable molecular weight. The polyacids used herein include, but are not limited to, homopolymers and copolymers based on polycarboxylic acids, including those that have been hydrophobically or hydrophilically modified, e.g., polyacrylic acid or polymethacrylic acid or maleic anhydride with various monomers such as styrene, acrylate or methacrylate esters, diisobutylene, and other hydrophilic or hydrophobic monomers as well as the salts of the aforementioned dispersants, and mixtures thereof. The molecular weight of such polyacids dispersant is from 400 to 50,000, preferably from 400 to 30,000, preferably from 500 to 10,000, preferably from 1,000 to 5,000 and preferably from 1,500 to 3,000.

Antifoaming agents and/or defoaming agents being used herein include, but are not limited to, silicone-based and mineral oil-based defoamers. Surfactants for use herein include anionic, nonionic, cationic surfactants and amphiphilic surfactant. Preferably anionic and nonionic surfactants, and more preferably, nonionic surfactants are used.

The biocides that can be used in the present invention are organic or inorganic biocides. Examples are described in US Patent No. 4127687 to DuPont, in US Patent No. 4898895 to Masuoka et al, and in WO1995032862A1. Preferably, the biocide(s) is with the active structure of diiodomethyl-p-tolylsulfone, 4,5-dichloro-2-octyl-2H-isothiazol-3-one (DCOIT), chloromethylisothiazolinone, methylisothiazolinone, or mixtures thereof.

The preparation of the coating composition involves the process of selecting and admixing appropriate coating ingredients in the correct proportions to provide coatings with specific processing and handling properties, as well as a final dry coating film with the desired properties.

The aqueous coating composition may be applied by conventional application methods including, but not limited to, brushing, roller application, and spraying methods such as air-atomized spray, air-assisted spray, airless spray, high volume low pressure spray, and air-assisted airless spray.

Suitable substrates include, but are not limited to, concrete, cement board, Medium Density Fiberboard (MDF) and particle board, gypsum board, wood, stone, metal, plastics, wall paper and textile. Preferably, all the substrates are pre-primed by aqueous or solvent- borne primers.

Examples

The experimental methods in the examples, when not described in detail, are contemplated to follow normal conditions in the art, for example, handbooks of polymer chemistry, or follow conditions suggested by chemical or instrument manufacturers.

I. Raw Materials

Product Supplier

ACRYSOL™ DR-73 Thickener Dow Chemical Company

ACRYSOL™ DR-72 Thickener Dow Chemical Company

ACPvYSOL™ TT-935 Rheology Modifier Dow Chemical Company

ACRYSOL™ RM-2020 NPR Rheology

Dow Chemical Company

Modifier CELLUSIZE™ QP 30000H Thickener Dow Chemical Company

China National Pharmaceutical Group

Propylene Glycol Solvent

Corporation

AMP™ 95 Base Dow Chemical Company

OROTAN™ 1288 Dispersant Dow Chemical Company

TRITON™ CF-10 Wetting Agent Dow Chemical Company

DISPELAIR™ CF-246 Defoamer Blackburn Chemicals

TI-PURE™ R-902 Pigment DuPont

TALC-800 Extender Meijia Chemical Company

CC-700 Extender Guangfu Building Materials Group (China)

DB-80 Extender Jinyang Gaoling Co., Ltd. (China)

CELITE 499 Extender Zhedong Guizaotu Company

TEXANOL™ Coalescent Eastman

ROPAQUE™ Ultra E Opaque Polymer Dow Chemical Company

PRIMAL™ SF-018 Binder Dow Chemical Company

PRIMAL™ AS-380 Binder Dow Chemical Company

PRIMAL™ TT-935 Rheology Modifier Dow Chemical Company

TERGITOL™ 15-S-40 Wetting agent Dow Chemical Company

II. Testing method for anti-dewing performance

Anti-dewing performance was evaluated according to TT-C-492C, FEDERAL SPECIFICATION, COATING COMPOUND, PAINT ANTISWEAT (31 MAY 1974), with some modifications. Two steel conic containers were painted with 20g (weight of wet paint) different coatings respectively. The height of the cone was 98 mm and the bottom radius of the cone is 53 mm. After drying the conic container for 24 hours at room temperature, 0°C ice water was added into the conic container. The temperature of outside environment was 23°C with 45% relative humidity. A bottle was put below the conic container to collect the dew drops. The time when the first drop of dew drips down into the bottle was defined as the dew time which was used to quantify the anti-dewing performance. The longer the dew time is, the better the anti-dewing performance is.

III. Experimental Examples Example 1 : Preparation of poly( sodium styrene sulfonate) (PSSS) homopolymer and copolymer

i. PSSS-1 to PSSS-5

Dissolved 50g sodium styrene sulfonate (SSS) in 200g Di water, and charged both to a 1 -liter four-neck flask reactor with stirring and condenser. Heated the reactor with nitrogen being blown in. When the reactor's temperature reached 80°C, charged an initiator, sodium persulphate (SPS), into the reactor. Calculating the amount of the sodium persulphate to control the molecular weight of the final product poly (sodium styrene sulfonate) (PSSS). When the temperature increased to 86°C, held the reaction at this temperature for 2 hours. The reaction product was filtered through a 100M and a 325M filter, and the final product, 20 wt.% solid PSSS aqueous solutions, were obtained. The weight-molecular weights of the PSSSs are listed in table 1.

Table 1. Average molecular weights of PSSS samples

ii. PSSS-6, purchased from Sigma-Aldrich Co. LLC, was a 30 wt.% poly(sodium 4-styrene- sulfonate) water solution, with its weight-average molecular weight being 70,000. iii. P(SSS-AAEM)

Dissolved 40g SSS in 183g Di- water, and charged both into a 1 -liter four-neck flask reactor with stirring and condenser. Dissolved lOg AAEM in a 6g 25% NaOH aqueous solution with stirring to get an AAEM aqueous solution. Charged the AAEM aqueous solution to a reactor. After heated the reactor to 88 °C with N₂ being blown in, charged l . lg SPS and 0.5g 3- mercaptopropionic acid (MP A) into the reactor to start polymerization. Reaction temperature was kept at 88°C for one hour to get a SSS-AAEM copolymer. The weight-average molecular weight of P(SSS-AAEM) is 207,000. iv. P(SSS-DAAM) Dissolved 40g SSS and 2g DAAM in 183g Di-water, and charged both into a 1 -liter four- neck flask reactor with stirring and condenser. After heated the reactor to 88 °C with N₂ being blown in, charged 3g SPS and lg MPA into the reactor to start polymerization. Reaction temperature was kept at 86°C for 2 hours. When the polymerization was finished, the pH of the solution was adjusted to 9.0 by adding ammonia. Added 1.64g ADH into the reaction system to get a SSS-DAAM copolymer. The weight-average molecular weight of P(SSS-DAAM) is 12,000. v. P(SSS/St)

Dissolved 269g sodium styrene sulfonate (SSS) in 1076g Di-water to form monomer emulsion \# (ME 1#). Dissolved lg SLS (28% solid), 29.89g styrene and 2.99g MPA in lOg Di-water to prepare monomer emulsion 2 (ME 2#). Charged HOg Di-water to a 1 -liter four- neck flask reactor with stirring and condenser; then heated the reactor with nitrogen being blown in. When the reactor temperature reached 90°C, charged 2g initiator sodium persulphate (SPS) into the reactor and observed for a 1~2°C temperature increasing. When the temperature started to drop for 1°C, fed ME 1# and ME 2# together and the feed lasted for 120 minutes. Meanwhile, co-fed a catalyst solution containing 0.82g SPS and 22g Di-water and the feed lasted for 120 minutes. When all feeds were completed, cooled the reactor temperature to 65°C and shotted chase promoter (9ppm FeS0₄ · 7H₂0 and 6ppm Versene) into the reactor, then co-fed 0.2% t-BHP and 0.15% IAA into the reactor and the feed lasted for 30 minutes. All the charges were based on monomers. The reaction product was filtered through a 100M and a 325M filter, and the final product, a 20 wt.% solid Poly (SSS-co-St) emulsion was obtained. The weight-average molecular weight of it is 33,000. vi. P(SSS/BA)

Used the same process as the above preparation for P(SSS/St-2), but replaced all Styrene with BA. The weight-average molecular weight of it is 42,800 vii. PAMPS

Used the same process as above preparation for PSSS-5, but replaced all SSS with AMPS. The weight-average molecular weight of it is 10,000. ix. P(SSS/AMPS) Used the same process as above preparation for PSSS-5, but replaced 20% of SSS with AMPS. The weight-average molecular weight of it is 9,000.

Example 2: Preparation of aqueous coating compositions

Paint 1 - Paint 5:

Latex 1 to Latex 5 were prepared via blending 500g PRIMAL™ SF-018 Binder and lOOg 20%) poly(sodium styrene sulfonate) (PSSS-1 to PSSS-5, respectively) water solution. Paint 1 to paint 5 containing Latex 1 to Latex 5, respectively were prepared using the following procedure. The grind ingredients as listed in Table 2 were mixed using a high speed Cowles disperser. The let-down ingredients as listed in Table 2 were mixed with the grind ingredients using a conventional lab mixer. The pigment volume concentrations (PVCs) of the resulting paints were 40%> (PVC40). The volume solids of the resulting paint were 35.5%. The weight solids were 50.7%>.

Table 2. PVC40 Aqueous Coating Composition of Paint 1 to 5

Ingredients (in kgs) Paint 1 to 5

Grind

Water 167.92 CELLUSIZE QP 30000H Thickener 1.00

OROTAN 1288 Dispersant 4.00 DISPELAIR CF-246 Defoamer 3.00 TERGITOL 15-S-40 Wetting agent (30%) 4.99 AMP 95 Base 3.00 CELITE 499 Extender 12.64 TI-PURE R-902 Ti0₂ 206.46 DB-80 Extender 34.41

TALC-800 Extender 64.79

Grind Sub-Total 502.19

Let Down

Anti-Dewing Latex 1-5 Binder 403.35 ROPAQUE Ultra E Opaque Polymer 25.80 ACRYSOL RM-2020 NPR Rheology Modifier 10.00 PRIMAL TT-935 Rheology Modifier 4.00 DISPELAIR CF-246 Defoamer 3.00

Water 51.67

Total 1000.00

Paint 6 Latex 6 was prepared via blending 500g PRIMAL™ SF-018 and 125g 20% poly(sodium styrene sulfonate-co-acetoacetoxyethyl methacrylate) (P(SSS-AAEM)) water solution. The weight ratio of sodium styrene sulfonate to acetoacetoxyethyl methacrylate was 4: 1. Paint 6 containing Latex 6 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%>. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 7

Latex 7 was prepared via blending 500g PRIMAL™ SF-018 and 125g 20% P(SSS-DAAM) water solution. The weight ratio of sodium styrene sulfonate to DAAM was 20: 1. Paint 7 containing Latex 7 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%>. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%. Paint 8

Latex 8 was prepared via blending 500g PRIMAL™ SF-018 and 125g 20% poly (sodium styrene sulfonate) (PSSS-6) water solution. Paint 8 containing Latex 8 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 9

Latex 9 was prepared via blending 500g PRIMAL™ SF-018 and 87.5 g 20% poly (sodium styrene sulfonate) (PSSS-3) water solution. Paint 9 containing Latex 9 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 10

Latex 10 was prepared via blending 500g PRIMAL™ SF-018 and 62.5 g 20% poly (sodium styrene sulfonate) (PSSS-3) water solution. Paint 10 containing Latex 10 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 11 - Comparative paint Paint 11 containing only PRIMAL™ SF-018 as binder was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%. Paint 12 - Comparative paint

Paint 12 containing only PRIMAL™ AS-380 as binder was prepared using the following procedure. The grind ingredients listed in Table 3 were mixed using a high speed Cowles disperser. The let-down ingredients listed in Table 3 were mixed with the grind ingredients using a conventional lab mixer. The PVC of the resulting paint was 80% (PVC80). The volume solids of the resulting paint was 53.8%. The weight solid was 48%.

Table 3. PVC80 Aqueous Coating Composition of Paint 12

Paint

Ingredients (in kgs) 12

Grind

Water 160.00

PROPYLENE GLYCOL Solvent 10.00

OROTAN 1288 Dispersant 9.00

DISPELAIR CF-246 Defoamer 1.00

TRITON CF-10 Wetting Agent 1.80

CC-700 Extender 380.00

TI-PURE R-902 Ti0₂ 70.00

DB-80 Extender 85.00

Grind Sub-Total 716.80

Let Down

PRIMAL AS-380 Binder 110.00

TEXANOL Coalescent 11.00

DISPELAIR CF-246 Defoamer 0.50

Aqueous Ammonia (28%) 2.00

ACRYSOL DR-73 Thickener 8.00

ACRYSOL DR-72 Thickener 5.00

Water 146.70

Total 1000.00

Paint 13

Prepared Latex 13 via blending 500g PRIMAL™ SF-018, 125 g 20% poly (sodium styrene sulfonate) (PSSS-3) water solution and 3.0 g 25% zinc oxide water slurry. Paint 13 containing Latex 13 was prepared following the procedure of making paint 1. The PVC of the resulting paints was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%. Paint 14

Prepared Latex 14 via blending 500g PRIMAL™ SF-018, 125 g 20% poly (sodium styrene sulfonate-co-styrene) (P(SSS/St)) water solution. The weight ratio of SSS to styrene in the P(SSS/St) is 90 to 10. Paint 14 containing Latex 14 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 15

Prepared Latex 15 via blending 500g PRIMAL™ SF-018, 125 g 20% poly (sodium styrene sulfonate-co-butyl acetate) (P(SSS/BA)) water solution. The weight ratio of SSS to styrene in the P(SSS/BA) is 90 to 10. Paint 15 containing Latex 15 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%. The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%.

Paint 16

Prepared Latex 16 via blending 500g PRIMAL™ SF-018, 125 g 20% poly (2-Acrylamide-2- methylpropanesulfonic acid) (PAMPS) water solution. Paint 16 containing Latex 16 was prepared following the procedure of making paint 1. The PVC of the resulting paint was 40%). The volume solids of the resulting paint was 35.5%. The weight solid was 50.7%. IV. Results:

Dewing is related to the PVC of the paint in architecture coating area according to GU Jian- yong et al. to CN 102072921 A. The lower the PVC is, the more serious the dewing is. Below critical pigment volume concentration (CPVC) paints have serious dewing, while above CPVC paints rarely have dewing issues.

The experiments of the invention were conducted in commonly used 40 PVC paints and comparative 80 PVC paints. In this invention, the CPVC value for PVC40 paints is calculated as 59, thus PVC40 paints are below CPVC. The CPVC value for PVC 80 paints is calculated as 64.9, thus PVC 80 paints are above CPVC This invention relates to binder compositions and their applications in anti-dewing architectural paints. The binder composition of the present invention comprises a homopolymer and/or predominant copolymer of sodium styrene sulfonate) (SSS) as an additive to reduce the dewing of the paint made by the binder composition.

Predominant copolymer of "A" means the content range of "A" in the copolymer is higher than 80%, preferably higher than 90%, and more preferably higher than 95%.

The detailed testing results are shown in Table 4

Table 4. Summary of the Anti-dewing Testing Results Paint No. Second polymer Mw Second polymer in the PVC Dew

binder composition (% by Time solid)

Paint 1 * PSSS-1 7,500 7.5% 40 35

Paint 2 PSSS-2 10,700 7.5% 40 48

Paint 3 PSSS-3 13,000 7.5% 40 52

Paint 4 PSSS-4 18,600 7.5% 40 50

Paint 5 PSSS-5 23,100 7.5% 40 52

Paint 6 PSSS-C 12,000 7.5% 40 52

Paint 7 PSSS-D 11,000 7.5% 40 50

Paint 8 PSSS-6 70,000 7.5% 40 55

Paint 9 PSSS-3 13,000 5.8% 40 48

Paint 10 PSSS-3 13,000 3.9% 40 40

Paint 1 I * 40 32

Paint 12* 80 55

Paint 13 PSSS-3 plus ZnO 13,000 7.5% 40 50

Paint 14 P(SSS/St) 33,000 7.5% 40 38

Paint 15 P(SSS/BA) 42,800 7.5% 40 40

Paint 16 PAMPS 10,000 7.5% 40 42

*Paint 1, 11, and 12 are comparative examples. Paint 11 and 12 are used as benchmarks. Paint 11 has serious dew formation, while Paint 12 has rare dew formation. Paint 1 has no significant differences in dew time compared with that of Paint 11.

Paint 11 was a common 40 PVC paint, i.e., below CPVC, having serious dew formations in practical application. The dew time of Paint 11 was 32 min. according to the modified TT-C- 492C Standard. Paint 12 was a common 80 PVC paint, i.e., above CPVC, which rarely had dew formation in practical applications. The testing dew time of Paint 12 was 55 min. and was deemed as the target of dew performance of the present invention. The results showed that when PSSS was added to the formulation, there was an obvious increase in dew time for 40 PVC paints (representative for below CPVC paints). The results of Paint 2 to Paint 5 and Paint 8 proved that when the Mw of PSSS was higher than 13,000, it provided the best anti- dewing effect to the paints (with dew time ranging from 50 to 55 min.). When the Mw of PSSS was lower than 13000, the dew time decreased with the decrease of the Mw, and when it reached 7,500 (Paint 1), the dew time (35 min.) was only a little higher compared with that of Paint 11 (below CPVC paint). 7,500 was the bottom line of Mw of PSSS for delivering anti-dewing performance.

In Paints 9 and 10, the dosage of PSSS differed from 3.9% to 5.8% based on the solid of aqueous latex PRIMAL™ SF-018 binder composition. The dew time was shortened with lower dosage of PSSS (Paint 10). At 3.9% PSSS dosage of Paint 10, the dew time was only 40 min.

For Paints 6 and 7, copolymers of SSS with functional monomers were added to the 40 PVC formulations. Both of them showed good anti-dewing performance compared with Paint 11 did.

In Paint 13, ZnO was added to a common 40 PVC paint formulation with 10% dosage of PSSS-3. It showed good anti-dewing performance with 50 min. dew time.

In Paint 14, the copolymers of SSS and styrene were added to formulation. The results showed that 10%> styrene containing SSS copolymer P(SSS/St) was better than Paint 1 1 comprising only PRIMAL™ SF-018.

Paint 15 was formulated with SSS and butyl acrylate (BA) copolymer. The ratio of SSS to BA is 9: 1. It showed a better 40 min. anti-dewing performance which was higher than Paint 11 did.

Paint 16 was formulated with AMPS homopolymer. It showed a better anti-dewing performance than Paint 11. Paint 16 had an acceptable dew time (42 min.) compared with that of Paint 11.

From the data, it might be concluded that the second polymer played a much better anti- dewing role when it was a homopolymer of sodium styrene sulfonate.

Claims

1. A binder composition for below critical pigment volume concentration coating comprising:

a) from 10% to 80%> by wet weight based on the total wet weight of the binder composition, at least one aqueous emulsion polymer; and

b) from 2% to 10% by dry weight based on the total dry weight of the binder composition, a second polymer comprising sodium styrene sulfonate, 2-acrylamide-2- methylpropanesulfonic acid or the combination thereof;

wherein the molecular weight of the second polymer is from 10,000 to 70,000.

2. The binder composition according to claim 1 wherein the aqueous emulsion polymer comprises, as polymerization units, acrylate monomers, styrene monomers, vinyl acrylate monomers, or the mixture thereof.

3. The binder composition according to claim 1 wherein the second polymer further comprises, as polymerization units, from 0.1% to 20%> by weight based on the total weight of the second polymer, an AAEM.

4. The binder composition according to claim 1 wherein the total weight of sodium styrene sulfonate and/or 2-acrylamide-2-methylpropanesulfonic acid is in a range of from 80%) to 100%) by dry weight based on the total dry weight of the second polymer.

5. The binder composition according to claim 1 wherein the second polymer is a homopolymer of sodium styrene sulfonate.

6. The binder composition according to claim 1 wherein the second polymer further comprises, as polymerization units, from 0.1 % to 20%> by weight based on the total weight of the second polymer, a DAAM, and the binder composition further comprises from 0.1% to 20% by weight based on the total weight of the binder composition, an ADH.

7. The binder composition according to claim of 1 wherein the binder composition further comprises, from 0.005%) to 0.3%> by weight based on the total weight of the binder composition, ZnO.

8. A coating composition comprising the binder composition according to any one of claim 1 to 7.