GB2566726A

GB2566726A - Aqueous coating composition

Info

Publication number: GB2566726A
Application number: GB1715402.2A
Authority: GB
Inventors: Léger Pierre
Original assignee: Dow Silicones Corp
Current assignee: Dow Silicones Corp
Priority date: 2017-09-22
Filing date: 2017-09-22
Publication date: 2019-03-27
Also published as: WO2019060614A1; GB201715402D0

Abstract

An aqueous coating composition comprises a water-based resin binder, at least one surfactant, and a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition, wherein the active content (solid content) of the emulsion composition is ≥2 wt.% of the coating composition. Typically, the binder includes a self-crosslinkable acrylic resin with a Tg of 10-35ºC. The copolymer emulsion may be obtained by emulsion polymerisation of a vinyl monomer and a carbosiloxane dendrimer in the ratio of 0:100 to 99.9:0.1 together with 0.01-20 pbw surfactant and 0.01-20 pbw radical polymerisation initiator for each 100 pbw of the combined vinyl monomer and carbosiloxane dendrimer. The dendrimer may have the formula, Y-Si-[O-Si(R2)-X]3, wherein Y is a radically polymerisable organic group, R is C1-10 alkyl or aryl, and X is a particular silylalkyl group. The copolymer emulsion is used as a water-based paint additive, preferably to decrease surfactant leaching and increase stain resistance of the coating composition.

Description

AQUEOUS COATING COMPOSITION [001] Technical Field [002] The present invention relates to an aqueous coating composition such as a water-based paint, using a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition. The present invention further relates to the use of a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition as a waterbased paint additive, particularly but not exclusively to decrease the surfactant leaching of an aqueous coating composition.

[003] Background Art [004] Various silicone-grafted vinyl copolymer emulsion compositions comprising a vinyl monomer and a carbosiloxane dendrimer are known from EP 1 095 953 A2. The emulsion composition is characterised by excellent storage stability and by the ability to form a film or coating that exhibits an excellent water repellancy.

[005] Also known in the art are various carbosiloxane dendrimer non-emulsion additives for a coating agent which exhibit a compatibility with resins, and which comprise a co-polymer that contains a hydroxyl group and a group having a carbosiloxane dendrimer structure, as set out in WO 2012/091178 A1.

[006] However, problems still occur in relation to the leaching of surfactants in aqueous coating compositions such as water-based paint. Surfactant leaching is sometimes called a ‘snail trail of resistance’ or just ‘snail trail’. Such leaching occurs on both interior and exterior walls, where vertical marks are seen on the paint, and which are usually sufficiently visually unsightly as to require re-painting. Typically the marks occur as paint is drying, and the atmosphere is cold, or is humid, or there is a heavy dew fall, or there is rain. Surfactants in the dried or drying paint migrate (or leach) to the wall’s surface towards the wetness or dampness, and then dry on the surface. The migration of salts causes the vertical marks or streaks, which then typically follow a gravitational direction to form vertical marks.

[007] Technical Problem to be solved

An object of the present invention is to provide an aqueous coating composition with reduced surfactant leaching. A further object of the present invention is to provide a use and a method of decreasing the surfactant leaching of an aqueous coating composition.

[008] Another object of the present invention is to provide an aqueous coating composition with improved stain resistance. A further object of the present invention is to provide a use and a method of increasing the stain resistance of an aqueous coating composition.

[009] Summary to the Invention [0010] The present inventors achieved the present invention as a result of extensive investigations directed to solving the problem described above. The problem is solved by an aqueous coating composition comprising:

(A) a water-based resin binder, (B) at least one surfactant, and (C) a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition, wherein the active content of the carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition is 2.0 weight % or more of the aqueous coating composition.

[0011] The problem is also solved by the use of various carbosiloxane dendrimergrafted vinyl copolymer emulsion compositions comprising a carbosiloxane dendrimer-grafted vinyl copolymer, as a water-based paint additive.

[0012] The problem is also solved by a method of decreasing the surfactant leaching, or of increasing the stain resistance, of an aqueous coating composition, comprising at least the step of adding a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition comprising 2.0 weight % or more active content of carbosiloxane dendrimer-grafted vinyl copolymer to the aqueous coating composition.

[0013] Detailed Description of the Invention [0014] The aqueous coating composition of the present invention is described in detail below.

[0015] The aqueous coating composition may comprise any paint or other coating agent which is ‘water-based’, which includes one or more of the group comprising: organic binder emulsion (typically acrylic or styrene acrylic copolymer), dispersants, fillers and pigments, defoamers, thickeners, coalescent solvent, water, biocides, pH modifiers. Water-based paints are increasingly preferred to organic solvent-based paint to avoid toxicity issues. Water-based paints can also be fast drying, have easier application, and allow easier cleaning of equipment.

[0016] The aqueous coating composition according to the present invention characteristically contains component (A) a water-based resin binder. The waterbased resin binder may be one or more of the group comprising: pure acrylic emulsions, styrene acrylic copolymer emulsions. Binders include synthetic or natural resins such as alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE) or siloxanes. The water-based binder can be exemplified by acrylic resin binders, which may comprise less than 0.5wt% alkyl phenol ethoxylates (and in some embodiments substantially free from alkyl phenol ethoxylates). The acrylic resin binders may also be self-cross-linking. The acrylic resin binders may have a solids content of 40-55wt%, more particularly 40-50wt%, even more particularly 43-47wt%. The acrylic resin binders may pH of 7-11, more particularly 8-10. The minimum film formation temperature may be -5-20°C, more particularly 0-19°C. One preferred component (A) is exemplified to be a self-cross-linkable acrylic resin having a Tg ranging from 10 to 35 °C, having a hydrophobic property derived from having a higher content for hydrophobic acrylate monomers. Such a water-based resin binder can be emulsified with any type of surfactants or combinations thereof. With respect to stability and solubility in relationship with component (C) in the composition of the present invention, anionic surfactants are most preferred to emulsify a self-crosslinkable resin into water phase. Suitable acrylic resin binders include SG-380 and Primal SF-016 (both Dow Chemical, Midland, USA). Primal SF-016 contains a higher amount of surfactant than SG-380.

[0017] The aqueous coating composition according to the present invention characteristically contains component (B) at least one surfactant. The at least one surfactant may be for dispersing pigments in the composition. The component (B) may be derived from dispersant or emulsifier for said component (A) in aqueous raw resin/paint composition, or derived from polymerization reaction material for component (A) or component (C). Needless to say, the component (B) can be independently blended to the inventive composition apart from said component (A) or component (C).

[0018] The at least one surfactant may be anionic or nonionic. Anionic surfactants include alkyl sulfates (sodium Lauryl sulfate), Fatty Alcohol Ether Sulfates (FAES), and Alkyl Phenol Ether Sulfates (APES). In particular, the alkyl sulfate may be sodium lauryl sulfate. Nonionic surfactants include polyethoxylates, such as ethoxylated alkyl polyethylene glycol ethers.

[0019] At least one surfactant able to disperse pigment may be neutralized acid copolymers, polycarboxylic acids, polyphosphates, modified fatty acid derivatives, or amine neutralized phosphoric acid ester.

[0020] The surfactant can be exemplified by a polycarboxlyate dispersant, such as OROTAN™ 731 A ER (Dow Chemical, Midland, USA) [0021] The aqueous coating composition according to the present invention characteristically contains component (C) a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition. Various carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition are known in the art. A range of carbosiloxane dendrimer-grafted vinyl copolymer emulsion compositions are defined in EP 1 095 953 A2, which is incorporated herein by way of reference, and which describes the emulsion polymerization of:

(a) a vinyl monomer;

(b) a carbosiloxane dendrimer as defined herein, (c) a surfactant; and (d) a radical polymerization initiator.

[0022] Optionally, the vinyl monomer (a) should contain a radically polymerizable vinyl group, but the type and properties of this monomer are not otherwise critical. Vinyl monomer (a) can be exemplified by lower alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, and isopropyl acrylate; lower alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate; higher acrylates such as n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2ethylhexyl acrylate, octyl acrylate, lauryl acrylate, and stearyl acrylate; higher methacrylates such as n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, lauryl methacrylate, and stearyl methacrylate; the vinyl esters of lower aliphatic acids, such as vinyl acetate and vinyl propionate; the vinyl esters of higher aliphatic acids, such as vinyl butyrate, vinyl caproate, vinyl 25 ethylhexanoate, vinyl laurate, and vinyl stearate; aromatic vinyl monomers such as styrene, vinyl toluene, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, and vinyl pyrrolidone; amino-functional vinyl monomers such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, and diethylaminoethyl methacrylate; amide-functional vinyl monomers such as acrylamide, N-methylolacrylamide, Nmethoxymethylacrylamide, isobutoxymethoxyacrylamide, N,N-dimethylacrylamide, methacrylamide, N-methylolmethacrylamide, N-methoxymethylmethacrylamide, isobutoxymethoxymethacrylamide, and Ν,Ν-dimethylmethacrylamide; hydroxylfunctional vinyl monomers such as 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxybutyl methacrylate, and 2-hydroxypropyl methacrylate; fluorinated vinyl monomers such as trifluoropropyl acrylate, perfluorobutylethyl acrylate, periluorooctylethyl acrylate, trifluoropropyl methacrylate, perfluorobutylethyl methacrylate, and perfluorooctylethyl methacrylate; epoxy-functional vinyl monomers such as glycidyl acrylate, 3,4epoxycyclohexyl methyl acrylate, glycidyl methacrylate, and 3,4epoxycyclohexylmethyl methacrylate; ether linkage-containing vinyl monomers such as tetrahydrofurfuryl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, polyethylene glycol acrylate, polypropylene glycol monoacrylate, hydroxybutyl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, tetrahydrofurfuryl methacrylate, butoxyethyl methacrylate, ethoxydiethylene glycol methacrylate, polyethylene glycol methacrylate, polypropylene glycol monomethacrylate; alkoxysilanes that contain a radically polymerizable unsaturated group, such as . CH₂=CHCOOC₃H₆Si(OCH₃)₃, . CH₂=C(CH₃)COOC₃H₆Si(OCH₃)₃, . CH₂=C(CH₃)COOC₃H₆Si(CH₃)(OCH₃)₂, . CH₂=C(CH₃)COOC₃H₆Si(CH₃)₂OCH₃, . CH₂=C(CH₃)COOC₂H₄OC₃H₆Si(OCH₃)₃, . CH₂=C(CH₃)COOCi₂H₂₄Si(OCH₃)₃, . CH₂=CHOC₃H₆Si(CH₃)(OC₂H₅)₂, . CH₂=CHSi(OCH₃)₃, . CH₂=CHSi(OC₂H₅)₃, and . CH₂=CHSi(C₄H₉)(OC₄H₉)₂ unsaturated group-functionalized silicone compounds such as organopolysiloxane (branched or straight-chain) bearing an acryl or methacryl group at a single terminal and polydimethylsiloxane bearing a styryl group at a single terminal; butadiene; vinyl chloride; vinylidene chloride; acrylonitrile and methacrylonitrile; dibutyl fumarate; maleic anhydride;

dodecylsuccinic anhydride; radically polymerizable unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid, as well as their alkali metal salts, ammonium salts, and organic amine salts; radically polymerizable unsaturated monomers that contain a sulfonic acid residue, e.g., styrenesulfonic acid, as well as their alkali metal salts, ammonium salts, and organic amine salts; quaternary ammonium salts that are derived from (meth)acrylic acid, such as 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride; and the methacrylate esters of alcohols that contain a tertiary amine group, such as the diethylamine ester of methacrylic acid, as well as the quaternary ammonium salts thereof. Preferred among the preceding are acrylate ester monomers, methacrylate ester monomers, and styrene monomers.

[0023] Also usable are multifunctional vinyl monomers, as can be exemplified by acryloyl-or methacryloyl-functional monomers such as trimethylolpropane triacrylate, pentaerythritol triacrylate, ethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane trioxyethylacrylate, tris(2hydroxyethyl)isocyanurate diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol di methacryl ate, neopentyl glycol dimethacrylate, trimethylolpropane trioxyethylmethacrylate, tris(2hydroxyethyl)isocyanurate dimethacrylate, tris(2-hydroxyethyl)isocyanurate trimethacrylate, the diacrylates and dimethacrylates of diols that are the adducts of ethylene oxide or propylene oxide on bisphenol A, and the diacrylates and di methacrylates of diols that are the adducts of ethylene oxide or propylene oxide on hydrogenated bisphenol A. Usable multifunctional vinyl monomers can also be exemplified by triethylene glycol divinyl ether, divinylbenzene, and unsaturated group-functional silicone compounds such as polydimethylsiloxane endblocked at both terminals by the styryl group and polydimethylsiloxane endblocked at both terminals by methacryloxypropyl.

[0024] Considering the above-listed vinyl monomers, the use in particular of vinyl monomer bearing a crosslinkable functional group makes it possible for the siliconegrafted vinyl copolymer to undergo crosslinking upon removal of the water from the composition after emulsion polymerization. The crosslinkable functional group under consideration can be, for example, an amino group, epoxy group, tetrahydrofurfuryl group, carboxyl group, hydroxyl group, blocked isocyanate group, or any of various silyl groups, e.g., halogenated silyl, alkoxysilyl, and acetoxysilyl. This crosslinking serves to improve the durability and solvent resistance of the silicone-grafted vinyl copolymer. The crosslinking can be of the self-crosslinking type or may be effected using a crosslinker, e.g., melamine, multifunctional epoxy, or multifunctional isocyanate. A crosslinking catalyst can also be used as necessary. Since in some cases the aforementioned crosslinkable functional groups can be hydrolyzed by water, it may be necessary to effect emulsification-using techniques known in the art so as to avoid their hydrolysis. Moreover, an additional stabilization of the composition of the present invention can be achieved by using hydrophilic vinyl monomer for a portion of component (A), said hydrophilic vinyl monomer being exemplified by acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, dimethylaminoethyl acrylate, 2-hydroxyethyl methacrylate, and dimethylaminoethyl methacrylate.

[0025] Optionally, the carbosiloxane dendrimer component (b) bears a radically polymerizable organic group having the following general formula:

Y - Si - (O - Si-XS3 wherein Y in this general formula is a radically polymerizable organic group and can be, for example, C₂ to C10 alkenyl or an acryl-, methacryl-, or styryl-functional organic group as defined by the following general formulas.

CH₂ = C-C(=O)-O-R⁵-

CH₂ = C-C(=O)-NH-R⁵-

R⁴ and R⁶ in these formulas are hydrogen or methyl; R⁵ and R⁸ are Ci to Cw alkylene; R⁷ is Ci to Cw alkyl; b is an integer from 0 to 4; and c is 0 or 1. These radically polymerizable organic groups can be exemplified by acryloxymethyl, 3acryloxypropyl, methacryloxymethyl, 3-methacryloxypropyl, 4-vinylphenyl, 3vinylphenyl, 4-(2-propenyl)phenyl, 3-(2-propenyl)phenyl, 2-(4-vinylphenyl)ethyl, 2-(3vinylphenyl)ethyl, vinyl, allyl, methallyl, and 5-hexenyl. R¹ in the preceding general formula for the carbosiloxane dendrimer (B) is Ci to Cw alkyl or aryl. The alkyl encompassed by R¹ can be exemplified by methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, cyclopentyl, and cyclohexyl. The aryl encompassed by R¹ can be exemplified by phenyl and naphthyl. Methyl and phenyl are preferred for R¹, and methyl is particularly preferred. X¹ is the silylalkyl group with the following formula when i = 1 (OR³)_ai R¹

I- I

X¹ = -R²-Si-(O-Si-X* ^{+ 1})3-_ai

R¹ in the preceding formula is defined as above. R² in the preceding formula represents C2 to Cw alkylene and can be exemplified by ethylene, propylene, and butylene. R³ in the preceding formula is Ci to Cw alkyl, for example, methyl, ethyl, propyl, or butyl. X^l+1 is selected from the group consisting of hydrogen, Ci to C10 alkyl, aryl, and the above-defined silylalkyl group, a' is an integer from 0 to 3. i is an integer with a value from 1 to 10 that specifies the generation of said silylalkyl group, i.e., that indicates the number of repetitions of this silylalkyl group. Thus, the carbosiloxane dendrimer (b) has the following general formula when the number of generations i is 1:

R¹ (OR³)_al R¹

I

Y-Si-{0-Si-R²-Si-(0-Si-R¹²)3. _al b (in the preceding formula, Y, R¹, R², and R³ are defined as above; R¹² is hydrogen or 10 is defined as for R¹; a¹ is defined as for a¹; and the average of the sum of the a¹values in each molecule is from 0 to 7). The carbosiloxane dendrimer (B) has the following general formula when the number of generations i is 2:

R¹ (OR³)ai R¹ (OR³)a2 R¹I I I I I

Y-Si-[-O-Si-R²-Si-{O-Si-R²-Si-(O-Si-R¹²)3-a2)3-ai]3 I I I

R¹ R¹ R¹ (in the preceding formula, Y, R¹, R², R³, and R¹² are defined as above; a¹ and a² are defined as for a¹; and the average of the sum of the a¹ and a² values in each molecule is from 0 to 25). The carbosiloxane dendrimer (b) has the following general formula when the number of generations i is 3:

R¹ (OR³)ai R¹ (OR³)a2 R¹ (OR³)_a3 R^{1 1 1 1 1 1 1 1}

Y-Si-[O-Si-R²-Si-[-O-Si-R²-Si-{-O-Si-R²-Si-(-C)-Si-R¹²)3-_a3}3__a2]3-ai]3 (in the preceding formula, Y, R¹, R², R³, and R¹² are defined as above; a¹, a² and a³are defined as for a'; and the average of the sum of the a¹, a², and a³ values in each molecule is from 0 to 79).

[0026] Compounds with the following average compositional formulas are examples of component (b), i.e., carbosiloxane dendrimer functionalized with a radically polymerizable organic group:

ch₃ ch₃ ch₃

I I I

CH₂=C-C(=O)-O-C₃H₆-Si-{O-Si-C2H4-Si-(O-Si-CH₃)₃}₃

I I

CH₃ ch₃ ch₃ ch₃ ch₃

CH₂=C-C(=O)-O-C₃H₆-Si-{O-Si-C₆Hi2-Si-<O-Si-CH₃)₃}₃

I I ch₃ ch₃ ch₃ ch₃

I I

CH₂=CH-C(=O)-O-C₃ H₆-Si-{O-Si-C₂H4-Si-<O-Si-CH₃)₃}₃

I I ch₃ ch₃ ch₃ ch₃ ch₃

I I I

CH₂=C-C(=O)-O-C₃H₆^Si-{O-Si-C₂H4-Si-(O-Si-C6H5)₃}₃ ' I I ch₃ c₆h₅ ch₃ ch₃ C₈Hi7

I I I

CH₂=C-C(=0>-O-C₃H₆-Si-{0-Si-C₂H4-Si-(0-Si-C₈Hi7)₃}₃

I I

CH₃ C₈Hi₇ ch₃ ch₃ ch₃ ;H₂=C-C(=0)-O-C₃H₆-Si-[O-Si-C2H4-Si-{O-Si-C2H4CH₃ ch₃ ch₃

I

-Si-(O-Si-CH₃)₃}₃]₃ l

ch₃

0»

cp

X <· . u _wx I x o—w—o — > .......

w

I w

X

M

5C ¥ X o-o-o w

I w

X

M

- O x I x o—co—o w

J

X s

ac ?=° 0-0

I!

M

X o

ch₃ ch₃ ch₃

I I I

CH2=C-C(=0)-NH—C₃H6~Si—{O-Si—C2H4—Si-(O-Si—CH₃)₃}₃

I I ch₃ ch₃

»

I π ·»

X ο

X

Μ χ Σ χ

Ο—<Λ—Ο

Μ ι

X

- φ « sis

Ο—€0-0 ι

X

Μ ο

χ ο

II ·«

X ο

ch₃ ch₃ (OCH₃)u ch₃

I III

CH₂=C-C(=O)-OC₃H₆-Si-{O-Si-C2H4-Si- (-0-Si-CH₃)i ₉}₃

I I ch₃ ch₃ ch₃ ch₃ (OCH₃)o.5 ch₃

I III

CH₂=C-C(=0)-O-C₃H₆-Si-{O-Si-C2H4-Si - (-O-Si-CH₃)₂ 5} 3

I I ch₃ ch₃ ch₃ ch₃ (OCH₃)o.5 ch₃

I III

CH₂=C-C(=O)-O-C₃H₆-Si-{O-Si-C₂H4-Si - (-O-Si-H)₂ 5} 3

I I ch₃ ch₃

ch₃ ch₃

I I

CH₂=CH—Si {OSi-C₂H4~Si-(OSi—CH₃)3) ₃

I I ch₃ ch₃ ch₃ ch₃

I I

CH₂=CH-Si {OSi-C₂H4-Si-<OSi-H)₃} 3

I I ch₃ ch₃ [0027] The carbosiloxane dendrimer described above can be synthesized, for example, by the method described in Japanese Patent Application Laid Open (Kokai) Number Hei 11-1530 (1,530/1999). In this method, the carbosiloxane dendrimer is synthesized by running a hydrosilylation reaction between an alkenyl15 functional organosilicon compound and an SiH-functional silicon compound with the following general formula:

Y-Si-(O-Si-H)₃ in which R¹ and Y are defined as above. The silicon compound with this formula can be exemplified by 3-methacryloxypropyltris(dimethylsiloxy)silane, 3acryloxypropyltris(dimethylsiloxy)silane, and 4-vinylphenyltris(dimethylsiloxy)silane. The alkenyl-functional organosilicon compound referenced above can be exemplified by vinyltris(trimethylsiloxy)silane, vinyltris(dimethylphenylsiloxy)silane, and 5hexenyltris(trimethylsiloxy)silane. This hydrosilylation reaction is preferably run in the presence of a transition metal catalyst, e.g., chloroplatinic acid or a platinumvinylsiloxane complex.

[0028] Optionally, the component (a) : component (b) polymerization ratio should be in the range from 0 : 100 to 99.9 : 0.1 as the component (a) : component (b) weight ratio, and is preferably from 50 : 50 to 95 : 5 and is more preferably from 60 : 40 to 90 : 10. The characteristic properties of the carbosiloxane dendrimer structure do not appear when the component (b) blending ratio is below 0.1.

[0029] Optionally, the surfactant (c) may be one or more surfactants typically used in the emulsion-polymerization of vinyl polymers, and the choice of such is not critical. It maybe e.g., an anionic surfactant, nonionic surfactant, cationic surfactant, or amphoteric surfactant. Anionic surfactants are exemplified by sodium oleate, sodium stearate, the sodium salt of dodecylbenzensulfonic acid, salts of alkylsulfate, and the sodium salt of polyoxyethylenealkylethersulfonic acid. Cationic surfactants are exemplified by quarternary ammonium salts such as dodecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, octyldimethylbenzylammonium hydroxide, decyldimethylbenzylammonium hydroxide, didodecyldimethylbenzylammonium hydroxide, dioctadecyldimethylbenzylammonium hydroxide, tallow trimethylammonium hydroxide, and coconut oil-trimethylammonium hydroxide. Nonionic surfactants are exemplified by polyoxyethylene laurylether, polyoxyethylene stearylether, polyoxyehtylene nonylphenolether, polyoxyethylene monostearate, sorbitan monostearate, and polyoxyethylene sorbitan monostearate.

Amphoteric surfactants are exemplified by amino acid-type surfactants and betainetype surfactants. Anionic surfactants, cationic surfactants or combinations of these surfactants are preferred. The surfactant (c) is more preferably a radically polymerizable surfactant which enhances the water-resistance of films formed from the emulsion composition. The radically polymerizable surfactant (c) should exhibit surfactancy and should be capable of undergoing radical polymerization, but its character is not otherwise critical. This radically polymerizable surfactant (c) may be an anionic, nonionic, or cationic surfactant.

[0030] Optionally, the anionic types of radically polymerizable surfactant (c) may be exemplified by compounds with the following structures.

Acrylic types of anionic surfactant:

R CH₂O-(AO)_x-R

CH₂=C-COOCH₂-CH-O(AO)_xSO₃M

R OCOR

I I

CH₂=C-COOCH₂-CR-CH₂SO₃M

R

I

CH₂=C-COO(AO)_XS0₃M

In the preceding structures, R is hydrogen or methyl, M denotes alkali metal, AO denotes alkylene oxide, and x is an integer from 1 to 50.

Allylic types of radically polymerizable anionic surfactant:

CH₂O-(AO)_X-R

CH2=CH-CH₂OCH₂-CH-O(AO)_xSO₃M ch₂coor

CH₂=CH-CH2-OOC-CH-SO₃Na

OH CH₂COOR

I I

CH₂=CHCH₂-OCH₂-CHCH₂-OOC-CH -SO₃Na

O(AO)_XSO₃M

In the preceding structures, R is hydrogen or methyl, M denotes alkali metal, AO 5 denotes alkylene oxide, and x is an integer from 1 to 50.

Maleic acid types of radically polymerizable anionic surfactant:

R¹

I

MOOC-C=CHCOO(AO)_XRO-(AO)_XH

R¹ R¹ ¹ 2 ¹MOOC-C=CHCOO(AO)_XR O-(AO)_XCO-CH₂CHCOOM

OH

ROOC-CH=CHCOOCH₂CHCH₂SO₃M

MOOC-CH=CHCOO(AO)_XR¹

R¹ in the preceding structures is hydrogen or methyl, R² denotes alkylene, M denotes alkali metal, AO denotes alkylene oxide, and x is an integer from 1 to 50.

Itaconic acid types of radically polymerizable anionic surfactant:

(CH₂)_xCOOR

CH2=C-COO(CH2)x-SO3M ch₂coor oh

CH₂=C-COOCH₂-CH-CH2SO₃M

In the preceding structures, R is hydrogen or methyl, M denotes alkali metal, and x is 10 an integer from 1 to 50.

[0031] The nonionic types of the radically polymerizable surfactant (c) can be exemplified by the following compounds.

Acrylic types of radically polymerizable nonionic surfactant:

R CH₂O-(AO)_x-R

CH₂=C-COOCH₂-CH-O(AO)_xH

R

I

CH₂=C-COO(EO)_x(PO)_x(EO)_xR

In the preceding structures, R is hydrogen or methyl, AO denotes alkylene oxide, EO denotes ethylene oxide, PO denotes propylene oxide, and x is an integer from 1 to 50.

Allylic types of radically polymerizable nonionic surfactant:

R CH₂O-(AO)_x-R

CH₂=C-CH₂OCH₂-CH-O(AO)xH

In the preceding structures, R is hydrogen or methyl, AO denotes alkylene oxide, 10 and x is an integer from 1 to 50. Maleic acid types of radically polymerizable nonionic surfactant:

R

I

RO(AO)_xOC-CH=CCOO(AO)xR

Itaconic acid types of radically polymerizable nonionic surfactant:

CH₂COO(AO)_xR

CH₂=C-COO(AO)xR

In the preceding structures, R is hydrogen or methyl, AO denotes alkylene oxide, and x is an integer from 1 to 50.

[0032] The cationic types of the radically polymerizable surfactant (C) can be 5 exemplified by the following compounds. Acrylic types of radically polymerizable cationic surfactant:

OH R

I I₊ ch₂=ch-cooch₂-chch₂n -r X

R

In the preceding structures, R is hydrogen or methyl, X is a halogen atom, AO 10 denotes alkylene oxide, and x is an integer from 1 to 50. Allylic types of radically polymerizable cationic surfactant: In the preceding structures, R is hydrogen or methyl, X is a halogen atom, AO denotes alkylene oxide, and x is an integer from 1 to 50.

[0033] The following surfactants are preferred from among those listed above:

R CH₂O4AO)x-R

CH₂=C—COOCEb-GH—O(AO)_xSO₃M

CH₂O-(AO)_x-R

CH₂=CH-CH₂OCH₂-CH-O(AO)_xSO₃M

R C^O-iAOK-R

CH₂=C-COQCH₂-CH-O(AO)_xH

R CH₂O-(AO)_x-R

CH₂=C-CH2OCH₂-CH-O(AO)_xH

OH R

I L .

CH₂=CH-COOCH₂-CHCH₂N -R X

R

OH R

I |₊ CH₂=CH-CH₂OCH-CH₂N -R X

R [0034] Component (c) can take the form of only a single surfactant or can be a combination of two or more surfactants. Component (c) may be used at from 0.01 to

20 weight parts and preferably at from 0.1 to 10 weight parts, in each case per 100 weight parts of the total amount of components (a) and (b).

[0035] Optionally, the radical polymerization initiator (d) may be selected from the radical polymerization initiators generally used for the emulsion polymerization of vinyl polymers, but its type and nature are not otherwise critical. Component (d) can be exemplified by inorganic persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; organoperoxides such as tert-butyl peroxymaleic acid, succinic acid peroxide, and tert-butyl hydroperoxide; watersoluble azo-type radical initiators such as 2,2'-azobis(2-(N15 benzylamidino)propane)hydrochloride, 2,2'-azobis(2-(N-2hydroxyethylamidino)propane)hydrochloride, and 2,2'-azobis(2-methyl-Nhydroxyethyl)propionamide; oil-soluble azo-type radical initiators such as 2,2'azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1-azobis-1cyclohexanecarbonitrile, dimethyl 2,2'-azobisisobutyrate, and 4,4'-azobis-420 cyanovaleric acid; and oil-soluble peroxides such as lauroyl peroxide, benzoyl peroxide, dicumyl peroxide, cyclohexanone peroxide, di-n-propyl peroxydicarbonate, and tert-butyl peroxypivalate. When a water-soluble radical initiator is used in the execution of the present invention, it may be mixed with the other components after their antecedent emulsification. Component (d) may be used at from 0.01 to 20 weight parts and is preferably used at from 0.1 to 10 weight parts, in each case per 100 weight parts of the total amount of components (a) and (b).

[0036] The emulsion compositions of component (C) may be obtained by combining from 0.01 to 20 weight parts radically polymerizable surfactant (c) and from 0.01 to 20 weight parts radical polymerization initiator (d) with 100 weight parts of the mixture of vinyl monomer (a) and carbosiloxane dendrimer (b), producing an emulsified dispersion therefrom in an aqueous medium, and effecting emulsion polymerization therein. As stated herein above, the component (a) : component (b) weight ratio is preferably in the range from 60 : 40 to 90 : 10. Component (a) is preferred to be a mixture of two or more vinyl monomers. By selecting component (a) as a mixture including an alkyl-modified vinyl monomer in higher content, the flexibility and Tg for the so-obtained copolymer can also be controlled. Components (a) to (d) may be emulsified and dispersed in combination with each other, or the radical polymerization initiator (d) may be added after the antecedent emulsification and dispersion process. The emulsified dispersion can be prepared using the usual emulsification devices, for example, a colloid mill or a homogenizer. Polymerization may be carried out for about 2 to 8 hours after preheating the reaction system to 50 to 90°C. This polymerization can be run by dropwise addition of the emulsified dispersion or after introducing the entire emulsified dispersion in one lot. The former technique is preferred because it facilitates temperature control. A chain transfer agent generally known for use in emulsion polymerizations may also be used in the present invention. The chain transfer agent can be exemplified by mercaptan compounds such as 2-mercaptoethanol, butyl mercaptan, n-dodecyl mercaptan, 3mercaptopropyltrimethoxysilane, and mercaptopropyl-functional polydimethylsiloxanes; by halogen compounds such as methylene chloride, chloroform, carbon tetrachloride, butyl bromide, and 3-chloropropyltrimethoxysilane; and by alpha-methylstyrene dimer. Surfactant lacking reactive functionality may be used — within a range that does not impair the characteristic features of the inventive composition — in combination with the surfactant (c). The postpolymerization particle size of the emulsion is not critical, but viewed from the standpoints of storage stability and preventing the appearance of aggregates is preferably no greater than 1.0 pm, more preferably no greater than 0.5 pm, and most preferably no greater than 0.3 pm. A thickener can be added and/or the specific gravity can be adjusted when the particle size is to be made 1.0 pm or above. The solids content of the inventive composition is preferably in the range from 15 to 60 weight% based on productivity and handling considerations. The obtained carboxysiloxane dendrimer-grafted vinyl copolymer in this emulsion composition preferably has at least some flexibility derived from its Tg (generally measured by DMA method) in the range 40 to 80°C, and an optional molecular weight (as determined by GPC-THF) in the range from 1 million to 5 million. Suitable commercially available emulsion products include Dow Corning® FA 4103 Silicone Acrylate Emulsion and similar products, which can be preferably employed.

[0037] Additives such as colorants, stabilizers, fats, oils, waxes, and fillers can be added to the aqueous coating compositions of the present invention as needed.

[0038] A characteristic feature of the inventive aqueous coating compositions of the present invention are a high loading of active content of the carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition, in particular being above 2.0 weight %, such as being 2.5 weight % or more, 3 weight % or more, 3.5 weight % or more, 4 weight % or more, 4.5 weight % or more, 5 weight % or more, 5.5 weight % or more, 6 weight % or more, 7 weight % or more, 8 weight % or more, 9 weight % or more, or 10 weight % or more. In some embodiments, the active content may be in the range 2.0 to 20 weight % or 2.0 to 15 weight % or 2.0 to 15 weight %. Any of these ranges represent a surprising high loading of the dendrimergrafted copolymer, whose presence may hinder the migration of water-soluble salts as the aqueous coating composition is drying.

[0039] The term active content as used herein relates to the active part of the emulsion composition, being the monomer content in the emulsion composition, typically accounting for 30% of the final composition. This is the same as the solid content of the emulsion composition. One or more of the surfactants could also be defined as a ‘solid component’ of the emulsion and can be separated with copolymer by removing water, to clarify the effect of this invention, it is needed to distinguish all surfactants (in raw paints and from emulsion) from co-polymer content. The co-polymer content can be calculated by the amount of monomers in emulsion polymerization.

[0040] Thus, the present invention further provides a use of a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition, in particular to decrease the surfactant leaching of an aqueous coating composition, especially as it dries or is drying.

[0041] Surfactant leaching is considered to be the mechanism through which water soluble components within the coating moves through the surface of a paint. The process usually occurs over a period of time, such as weeks, after initial drying of an aqueous coating composition is applied to a surface, and is possibly washed by rain, although it can be accelerated under certain atmospheric conditions (often in spring and in autumn time). In one example, the formation of condensation on a ‘freshly painted’ exterior facade due to temperature falling below dew point will cause surfactants to migrate to surface. When the condensation subsequently dries, the surfactants are deposited on the surface of the paint, causing shiny streaks or discoloration. Surfactant leaching is visually more apparent in dark, ultra deep colors, although it also happens for lighter colors, even for white paint, when the exudate has a tan color.

[0042] The present invention further provides a use of a carbosiloxane dendrimergrafted vinyl copolymer emulsion composition to increase the water contact angle of an aqueous coating composition.

[0043] The amount of carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition used in an aqueous coating composition may be above 2 weight % active content, such as being 2.5 weight % or more, 3 weight % or more, 3.5 weight % or more, 4 weight % or more, 4.5 weight % or more, 5 weight % or more, 5.5 weight % or more, 6 weight % or more, 7 weight % or more, 8 weight % or more, 9 weight % or more, or 10 weight % or more. In some embodiments, the amount may be in the range 2.0 to 20 weight %.

[0044] The present invention also provides a method of decreasing the surfactant leaching of an aqueous coating composition comprising at least the step of: adding 2 weight % or more active content of a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition comprising carbosiloxane dendrimer-grafted vinyl copolymer to the aqueous coating composition. The range 2 weight % or more may be 2.5 weight % or more, 3 weight % or more, 3.5 weight % or more, 4 weight % or more, 4.5 weight % or more, 5 weight % or more, 5.5 weight % or more, 6 weight % or more, 7 weight % or more, 8 weight % or more, 9 weight % or more, or 10 weight % or more. In some embodiments, the active content may be in the range 2.0 to 20 weight %.

[0045] It is also known that paint and coating surfaces can change following exposure to water, in particular exposure to rain or dew or steam, and a further characteristic of the present invention is to reduce or minimize any changes at paint surfaces following exposure to water or water vapor, which can be measured by contact angle.

[0046] Examples [0047] This invention is explained in greater detail below through working examples. Parts in the examples denote weight parts, and any percentages are by weight. The following methods were used to measure and evaluate the properties of the emulsion compositions and coatings.

[0048] Several loadings of a commercial Emulsion P1 carboxysiloxane dendrimergrafted vinyl copolymer emulsion, characterised by a Tg of 60°C and a molecular weight ranging from 1 million to 5 million, a carboxysilloxane monomer composition of 50% of other acrylic monomer, were added to a general paint composition having the following composition:

filler (blend calcium carbonate, silica, talc - PVC ca 70%), hydrophobic dispersant (ca 1,5%, ie a surfactant such as Orotan 731), thickener (cellulosic ie Cellosize QP4400, acrylic, ie ACRYSOL RM-935), biocide, silicone antifoam.

[0050] The loadings were defined as either 10%, 5%, 2.5% and 1.25% active content The active content percentages were based on the polymerized monomer fraction of the carboxysiloxane denfrimer grafted vinyl compolymer emulsion, for example 30% when residual composition being water used as dispersion medium during the emulsion polymerization process. Thus, 1.25% ‘active content’ corresponds to 4.17% of the Emulsion P1 as supplied, and once mixed with the paint composition.

[0051] The emulsion compositions were judged against;

(i) a ‘Non-silicone comparison’, being the same general paint composition listed above without any copolymer emulsion; and (ii) a ‘Silicone comparison’, being the same general paint composition listed above and a misture comprising 4% SILRES ® BS45 and 1% SILRES® BS1306 (both Walker Chemie AG, Germany) [0052] Snail trail and hydrophobic properties were evaluated following to experimental methods described below.

[0053] Experimental [0054] The snail trail test was based on painting a surface, allowing it to dry for 24 hours at room temperature and 50% RH, followed by applying 2μΙ drops of liquid H₂O to the painted surface, leaving them for 30 minutes, removing the H₂O by lifting up panels vertically and then evaluating the samples. The WCA (water contact angle) test was based on visual appearance of the drops of H₂O after 0 seconds and 60 seconds on the coatings. A 2μΙ drop of high purity water was applied to a test specimen surface using a liquid delivery system (1 ΟΟμΙ syringe). Images of the drop in contact with the substrate were captured by a video camera at specified time intervals following deposition. The contact angle between the drop and the substrate at various time intervals following drop deposition were determined by image analysis techniques on the captured images (according to ASTM D5725). The equipment used was a VCA Optima XE from AST Products, Inc.. The results are shown in Table 1 below (N: no trail appeared after water contact; Δ: slight trail was appeared; X: clear trail appeared and remained):

	10% active loading
WCA	snail trail
Os	60s
Emulsion P1: 10% active content	5	3	N
ref with silicone	3	1	X
ref without silicone	1	0	X
	5% active loading
WCA	snail trail
Os	60s
Emulsion P1: 5% active content	5	4	N
Silicone comparison’	3	1	X
Non-silicone comparison’	1	0	X
	2.5% and 1.25% active loading
WCA	snail trail
Os	60s
Emulsion P1: 2.5% active content	5	3	Ato N
Emulsion P1: 1.25% active content	5	3	Δ
Silicone comparison’	3	1	X
Non-silicone comparison’	2	0	X

Table 1 [0055] The evaluation scale used to obtained is shown in Table 2 below.

assess the water contact angles results

	WCA (degree)	snail
0s	60s
0	0-70	0-50	very visible
1	70-85	50-65	visible to very visible
2	85-95	65-80	slightly visible to visible
3	95-110	80-90	slightly visible
4	110-120	90-100	almost no mark
5	>120	>100	no mark

Table 2 [0056] House hold stain resistance was evaluated by post-adding the carboxysiloxane dendrimer-grafted vinyl copolymer emulsion to a ‘Control’ formulation having the composition set out in Table 3 below. The carboxysiloxane dendrimer-grafted vinyl copolymer emulsion was added at 2% emulsion solid content, or by using the carboxysiloxane dendrimer-grafted vinyl copolymer emulsion as a ‘Co-binder’, in a 60/40 dry ratio between the acrylic emulsion and the carboxysiloxane dendrimer-grafted vinyl copolymer emulsion (ie replacing 40% of dry

SG-380 with Emulsion P1). The Control and Co-binder formulations are set out in

Table 3 below (in parts by weight).

	Control	Co-binder
Water	87.6	85.7
Orotan 731 (surfactant)	15.5	15.1
Dow Corning 71 (defoamer)	1.6	1.5
Dow Corning 8590 (defoamer)	1.0	1.0
NH₄OH	0.5	0.5
TiO₂ CR 826 (pigment)	187.7	183.6
Imercarb 5L (filler)	30.4	29.7
Imercarb 2L (filler)	30.4	29.7
FinnTalc M15	50.6	49.5
Minex 4 (filler)	93.4	91.4

WATER	63.5	62.1
Dow Corning 108 F (defoamer)	3.9	3.8
SG 380 (binder)	369.9	217.1
UCAR Filmer IBT (coalescing agent)	12.0	7.8
Dowanol DPnB	2.2	0.5
Emulsion P1	0	217.1
HEUR (hydrophobically-modified ethylene oxide-based urethane)	8.6	3.8
WATER	41.4	0.0
TOTAL =	1000.	1000.0

Table 3 [0057] Stain methods: Seven different household stains were applied to panels painted with each of the compositions mentioned below and then left for 30 minutes. The panels were then washed for 10 seconds under tap water. Each panel then received 20 strokes from a scrubbing machine with water. The panels were then evaluated visually and dE measurements (spectrophotometric change of colour) were made (lower = better). Colour change was measured using a BYK spectrophotometer 45/0 geometry Cielab equation D65 illuminant, conforming to ASTM D2244. The results are shown in Table 4 below. Compared with the acrylic emulsion alone, in general, the coating formulation comprising carboxysiloxane dendrimer-grafted vinyl copolymer emulsion is lower in color change degree and show better stain proof performance, reflected by the lower color difference measured through dE.

	Blue dye	Wine	Coffee	Food dye	Red pastel	Lipstick	Soya sauce
Control	2.217	2.808	4.334	2.048	39.075	4.139	0.308
Acryl Em°/Co-binder	0.961	0.921	2.520	0.677	39.822	2.994	0.596
Acryl Em°+ Emulsion P1 with 2% active content	0.563	1.493	3.047	1.268	26.186	3.995	0.920

Table 4

Claims

1. An aqueous coating composition comprising:

2. The aqueous coating composition of claim 1, wherein component (A) includes at least one acrylic resin binder.

3. The aqueous coating composition of claim 2, wherein the acrylic resin binder is characterized by self-cross-linkable acrylic resin having a Tg ranging from 10 to 35 °C.

4. The aqueous coating composition of any one of the preceding claims wherein component (B) is an anionic or non-ionic surfactant.

5. The aqueous coating composition of any one of the preceding claims wherein component (C) is obtainable by the emulsion polymerization of:

(a) a vinyl monomer;

(b) a carbosiloxane dendrimer that contains a radically polymerizable organic group of the formula

Y - Si - (O - Si-xS3 wherein Y is a radically polymerizable organic group, R1 is Ci to Cw alkyl or aryl, and X1 is the silylalkyl group with the following formula when i = 1:

(OR3)ai R1

X* = -R2-Si-(O-Si-X1 + i)3-ai wherein R1 is defined as above; R2 is C2 to Cw alkylene; R3 is Ci to Cw alkyl; Xl+1 is selected from the group consisting of hydrogen, Ci to Cw alkyl, aryl, and the abovedefined silylalkyl group; i is an integer of from 1 to 10 that specifies the generation of said silylalkyl group; and a' is an integer from 0 to 3, and wherein the weight ratio of (a): (b) is from about 0 : 100 to 99.9 : 0.1;

(c) a surfactant, at from 0.01 to 20 weight parts for each 100 weight parts of the total of components (a) and (b); and (d) a radical polymerization initiator, at from 0.01 to 20 weight parts for each 100 weight parts of the total of components (a) and (b).

6 The aqueous coating composition of any one of the preceding claims wherein component (C) is able to form a film or coating.

7. The aqueous coating composition of any one of the preceding claims wherein the active content of the carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition is 2.5 weight % or more of the aqueous coating composition.

8. A use of a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition comprising a carbosiloxane dendrimer-grafted vinyl copolymer as a water-based paint additive.

9. A use as claimed in claim 8 to decrease the surfactant leaching of an aqueous coating composition.

10. A use as claimed in claim 8 to increase the stain resistance of an aqueous coating composition.

11. A method of decreasing the surfactant leaching of an aqueous coating composition comprising at least the step of:

adding a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition comprising carbosiloxane dendrimer-grafted vinyl copolymer in 2.0 weight % or more

5 of its active content to the aqueous coating composition.

12. A method of increasing the stain resistance of an aqueous coating composition comprising at least the step of:

adding a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition 10 comprising carbosiloxane dendrimer-grafted vinyl copolymer in 2.0 weight % or more of its active content to the aqueous coating composition.