Title:  Hydrophilic siloxane latex emulsions

United States Patent:  6,207,782

Assignee:  Cromption Corporation (Middlebury, CT)

Filed:  September 11, 1998

Emulsions and dispersions of polymers formed from acrylated hydrophilic polysiloxanes and their copolymers with acrylate/methacrylate comonomers are taught herein wherein the polymer is formed in a solvent via radically catalyzed polymerization. Such a polymer has utility in personal care applications, as well as textile finishes and coating formulations.

DETAILED DESCRIPTION OF THE INVENTION

The present invention describes radically polymerized acrylates/methacrylates of polyether modified polysiloxanes and their copolymers with organic acrylates, as well as emulsions including these polymers. The siloxanes have siloxane backbones with pendant polyether functionalities which polyethers are encapped with an acrylate or methacrylate functionality. The backbone may be linear, branched or cyclic. These acrylated siloxanes then are polymerized in a solvent to form an emulsion of the latex.

The acrylated siloxanes can be represented by Formula I

[R₃ SiO_1/2 ]_m [O_1/2 SiR₂ O_1/2 ]_n [SiO_3/2 R]_o [SiO_4/2 ]_p

wherein R is selected from the R¹ and P, wherein each R¹ can be the same or different and each is a monovalent hydrocarbon group; each P is R³ [O(C_b H_2b O)_z COCR⁴=CH₂ ]_g wherein, R³ is a poly valent organic moiety, which may be hydroxy substituted alkylene, g is the valency of R³ minus 1, R⁴ is hydrogen or methyl; b=2 to 4, preferably 2 to 3; z=1 to 1000, preferably 3 to 30; and m+n+p+o=1 to 100, preferably 2 to 20, at least one R is P; n=1 to 100; when O is not zero n/o<10:1; when p is not zero n/p<10:1; and m=0 to 10.

Preferably the acrylated siloxane is of the formula (II)

QR1₂ Si[OSiR1₂ ]_x [O--SiR¹ P]_y OSiR1₂ Q

wherein x, and y can be 0 or an integer, preferably each x and y are from 0 to 100, most preferably 0 to 25; Q can be R¹ or P, with the proviso that the average acrylate functionality is >1 unsaturated groups per molecule. In the preferred embodiment y=0 and Q=P.

Preferably R is a C₁ -C₄ alkyl, an aryl or alkaryl. Specifically preferred R are methyl, ethyl, phenyl and ethyl phenyl. R may include heteroatom substituents preferably, which are nonreactive with acrylates.

P may be branched with several polyether branches originating from the alkyl bridge to the silicon atom. For example, P may be an alkoxylated trimethylol propane monoallyl ether which has been hydrosilated onto the siloxane backbone and esterified. Other polyvalent precursors for P, which may be hydrosilated, alkoxylated and esterified are glycerol monoallyl ether, pentaerythritol allyl ether and trisopropanol amine allyl ether. In a preferred embodiment, g=1 and R³ is a linear C₂ -C₅ alkylene, most preferably C₂ -C₃.

Not all polyethers in P need be the same as each other. Preferable P structures are ones with ethylene oxide (b=2) contents of greater than 80% by weight of the alkylene oxide (C_b H_2b O) content, most preferably all of the alkylene oxide chain is ethylene oxide.

Said acrylates of Formula I are derived from the polyether polysiloxane copolymers wherein the polyethers are attached to the siloxane backbone through a non-hydrolyzable Si--C bond. Moreover, the polyethers should be uncapped so that the hydroxyl group may be (trans)esterified with the acrylate. Said polyether polysiloxanes are commercially available.

The esterification is catalyzed with a Bronstead acid if the acid is the starting acrylate. If an ester is used an acid or base can be used to catalyze the transesterification.

The acrylated silicone copolymers are polymerized to form polymers (latexes), or if desired, copolymers of Formula I with other comonomers (e.g., other esters). Said polymerization may be conducted in various solvents, catalysts and temperatures as are known in the art for polymerizing acrylates. Said polymerization should not be conducted on a surface to form a film. Rather, polymerization in a solvent allows for production of a crosslinked latex gel which has broader utility than film forming. The emulsion should contain less than or equal to 90 wt %, preferably less than 50 wt %, of the polymer in solvent. Suitable solvents include polar solvents, e.g., water and alcohol, and non-polar solvents, such as many hydrocarbons or low molecular weight cyclic or linear polydimethylsiloxanes. Preferably polydimethylsiloxanes should have a viscosity of less than 100 cSt (25^oC.).

Any organic acrylate or methacrylate can be employed in forming the copolymers with Formula I. Thus, for example, acrylic acid and methacrylic acid or their derivatives such as esters, nitrites and amides can be employed. The esters are preferred compounds. Specific examples of the acrylates that can be utilized are methyl acrylate, ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, vinyl acrylate, allyl acrylate, hydroxyethyl acrylate, perfluoroethyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate. A single acrylate or various combinations of acrylates can be employed in making the copolymers.

Copolymers of the acrylates/methacrylates of the polyether modified polysiloxanes, with the organic acrylates may consist of 1 to 99% by weight of the polysiloxanes, preferably 20-90% and most preferably 50-80% of the polysiloxane.

It is also an objective of the present invention to produce emulsions, comprising the polymerized acrylates/methacrylates polyether polysiloxanes copolymers and/or their copolymers with organic acrylates (i.e., latexes), which upon evaporation of water form films with good tactile properties and good integrity. These emulsions may in fact be dispersions of the latex.

One particular method to prepare emulsions is:

1. Dispersing an acrylate/methacrylate of polyether polysiloxane copolymers, as defined by Formula I, with or without a separate organic acrylate, using at 5-50% by weight of the siloxane emulsifiers selected from nonionic surfactants (such as alkylaryl-polyoxyethylene adducts and alkyl ethoxylates) or anionic surfactants (such as, carboxylates, sulfates, sulfonates, alkylaryl sulfonates and alkyl phosphates), to form a stable emulsion containing 10-50% of the dispersed siloxane phase, which can be further stabilized by addition of common thickeners, such as xanthan or guar gum, gellatin and cellulose derivatives.

2. Adding a free-radical catalyst, selected from the group of water soluble or oil soluble peroxides, such as hydrogen peroxide, ammonium persulfate, potassium persulfate, various organic peroxy catalysts, such as dialkyl peroxides, e.g., diisopropyl peroxide, dilauryl peroxide, di-t-butyl peroxide, dicumyl peroxide, alkyl hydrogen peroxides such as t-butyl hydrogen peroxide, t-amyl hydrogen peroxide, cumyl hydrogen peroxide, diacyl peroxides, for instance acetyl peroxide, lauroyl peroxide, benzoyl peroxide, peroxy ester such as ethyl peroxybenzoate, the azo compounds such as 2-azobis(isobutyronitrile), to the emulsion.

3. Heating the emulsion to or above the temperature necessary for initiating the radical reaction, typically 40 to 100^oC., depending on the catalyst, for 1-10 hours or until the unsaturated groups are consumed.

Alternatively, a water in oil emulsions, particularly water in polysiloxane emulsions, are prepared by combining water, anionic surfactant (e.g., sodium dodecyl sulfate) and free radical catalyst, in the aqueous phase and adding the acrylated/methacrylated polyether polysiloxane copolymer, followed by the polysiloxane and silicone surfactant to the agitated aqueous phase. The HLB of the anionic surfactant should be relatively high, i.e., above about 15, and the HLB of the silicone surfactant should be between about 4 and 9. Examples of the silicone surfactant are SILWET L-7622 and SILWET FZ 2108 (available from OSi Specialties, Inc., a subsidiary of Witco Corporation). The preformed emulsion is heated to at least about 80-90^oC. for about 2 to 4 hours. The copolymer should be present at 20-60 wt % of the emulsion and the internal aqueous phase should be present at 5-25 wt % of the emulsion. The polysiloxane should be present at 25-75 wt % of the emulsion. The amount of surfactants will be determined for each case as necessary.

Use

The emulsion may be translucent or milky, depending on the acrylate/methacrylate used. The emulsions are stable with no separation at up to about 90^oC. The viscosity of the emulsion can be from 0.01 to 10,000 cps (25^oC.). The dry oil phase (i.e., after the solvent has evaporated from the emulsion) can form smooth and soft films to stiff and brittle films, depending on the starting material and ratio of silicone to acrylate. Generally, the higher the silicone content, the softer the film.

The emulsions of the present invention can be used as ingredients of personal care formulations, including skin care, nail care, and hair care formulations, such as lipsticks, mascaras, nail polishes, foundations, lotions, creams, sunscreens, shampoos and conditioners, to improve their wear, tactile properties, and ease of application. They also can be used in textile and fiber treatments to impart smooth, soft feel and wettability to both natural and synthetic substrates including natural fibers such as hair, cotton, silk, flax and wool; synthetic fibers such as polyester, polyamide, polyacrylonitrile, polyethylene, polypropylene and polyurethane; and inorganic fibers such as glass or carbon fibers. The fabric substrate which can be treated with the copolymers of the present invention is exemplified by the fabric produced from the above-mentioned fibrous materials or blends thereof. These emulsions can be applied onto the substrate such as by spraying, dipping or kiss roll application or other application method typically employed in hair or textile treatment.

In general the emulsion is applied on skin, hair, fiber, textile or other substrate such that up to 5%, preferable 0.01 to 2.5% of the polymer by weight of the dry substrate remains on the substrate. Optionally other additives, commonly used to treat hair or textile substrates can be employed along with the copolymers of the present invention, including but not limited to additional surfactants, curing resins, preservatives, dyes, colorants, formularies.

Finally, the emulsions of the present invention can be incorporated into waterborne coating formulations for metals, plastic, wood and paper, such as varnishes, latex paints and roofing compositions.

Claim 1 of 20 Claims

We claim:

1. A liquid composition comprising:

a) a polymer formed from the polymerization in a solvent of monomers consisting essentially of acrylated or methacrylated polyether siloxane copolymers wherein the siloxane copolymer is of the formula

[R₃ SiO_1/2 ]_m [O_1/2 SiR₂ O_1/2 ]_n [SiO_3/2 R]_o [SiO_4/2 ]_p

wherein R is selected from R¹ and P, wherein each R¹ and P is the same or different and each R¹ is a monovalent hydrocarbon group; each P is

R³ [O(C_b H_2b O)_z COCR⁴=CH₂ ]_g

wherein, R³ is a polyvalent organic moiety, g is the valency of R³ minus 1, R⁴ is hydrogen or methyl; b=2 to 4, z=1 to 100, and m+n+p+o=1 to 100, at least one R is P; n=1 to 100; when o is not zero, n/o<10:1; when p is not zero, n/p<10:1; and m=0 to 10, with the proviso that the average acrylate functionality is >1 unsaturated groups (P) per molecule, and

b) said solvent.

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