WO2017116639A1

WO2017116639A1 - Aqueous silicone dispersion

Info

Publication number: WO2017116639A1
Application number: PCT/US2016/065253
Authority: WO
Inventors: Donald Liles; Kimberly QUACKENBUSH
Original assignee: Dow Corning Corporation
Priority date: 2015-12-28
Filing date: 2016-12-07
Publication date: 2017-07-06

Abstract

The present invention provides aqueous silicone emulsions comprising a crosslinked polyorganosiloxane, a polyvinyl alcohol polymer, and water, wherein the crosslinked polyorganosiloxane is a reaction product of (A) a polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups and (B) at least one self-catalyzing crosslinking agent having more than two leaving groups. The present invention also provide methods for making the emulsions and composition comprising the emulsions.

Description

AQUEOUS SILICONE DISPERSION

FIELD OF THE INVENTION

[0001] This invention is in the field of aqueous silicone emulsions comprising crosslinked polyorganosiloxanes. Particularly, the invention is useful for making emulsions of elastomers which when dried produce films for coating applications.

BACKGROUND OF THE INVENTION

[0002] Methods for producing emulsions from high viscosity polysiloxanes involve forming a thick phase emulsion by mixing a polysiloxane, at least one primary surfactant and water. Sometimes, at least one secondary surfactant is added to make the mixture. The mixture is then mixed using shear for a sufficient period of time until a desirable average particle size is achieved. The thick phase emulsion is then diluted with additional water to the desired silicone content to form the final emulsion.

[0003] To make stable aqueous silicone emulsion that froms an elastomer upon removal of the water, a reactive polydiorganosiloxane in the presence of a surfactant is combined with water, a crosslinking agent, and a catalyst. In some cases the cross-linking agent is a self- crosslinking compound so that an added catalyst may not be needed. The crosslinking of the reactive polydiorganosiloxane may take place either before or after the evaporation of the water, although crosslinking prior to the evaporation of water is more common. Upon the evaporation of water, the silicone emulsions may produce silicone elastomeric materials in the form of coatings, seals or caulks.

[0004] One disadvantage of prior aqueous silicone emulsions of pre-cured silicone elastomer is their limited usefulness as a slip additive in water-based coatings that contain organic solvents. Alcohols and coalescing solvents are known to destabilize silicone emulsions prepared with conventional surfactants.

[0005] Thus, the present invention provide aqueous silicone emulsions that use a self- catalytic crosslinking agent and that is also stable in water-based coatings that contain organic solvents, such as alcohols and coalescing solvents.

SUMMARY OF THE INVENTION

[0006] The present invention provides aqueous silicone emulsions comprising a crosslinked polyorganosiloxane, a polyvinyl alcohol polymer, and water, wherein the crosslinked polyorganosiloxane is a reaction product of (A) a polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups and (B) at least one self-catalyzing crosslinking agent having more than two leaving groups. The present invention provides compositions comprising the aqueous silicone emulsions.

[0007] The present invention also provides methods for making a crosslinked

polyorganosiloxane emulsions, the methods comprising: A. combining components:

i. polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups,

ii. at least one self-catalyzing crosslinking agent having more than two leaving groups,

III a polyvinyl alcohol polymer, and

IV. water;

B. mixing the components at a high shear to form an aqueous emulsion having a dispersed phase comprising components i and ii; and

C. reacting the polyorganosiloxane or a mixture of polyorganosiloxanes and the at least one self -catalyzing crosslinking agent to obtain a crosslinked

polyorganosiloxane emulsion.

DETAILED DESCRIPTION OF THE INVENTION

[0008] In one embodiment, the present invention provides aqueous silicone emulsions, the emulsions comprise a siloxane polymer or polymer mixture, a polyvinyl alcohol polymer, water and at least one self-catalyzing crosslinking agent. Optionally, the emulsions contain co-surfactants, in-situ reinforcers, stabilizers, and fillers which may be added before or after the formation of the emulsions. The emulsions are produced by mixing the components at a sufficiently high shear, which may optionally be diluted with water to a desired silicone content. The dispersed phase of the emulsions comprise siloxane polymer or polymer mixture and the self-catalyzing crosslinking agent. Crosslinking of the siloxane polymer takes place by reacting the siloxane polymer with the self -catalyzing crosslinking agent after formation of the emulsions.

[0009] In another embodiment, the present invention provides aqueous silicone emulsions comprising a crosslinked siloxane, a polyvinyl alcohol polymer, and water, wherein the crosslinked siloxane is a reaction product of (A) a siloxane polymer or polymer mixture and (B) at least one self-catalyzing crosslinking agent having more than two leaving groups. In one embodiment, the siloxane polymer or polymer mixture comprises a polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups, and the crosslinked siloxane is a crosslinked polyorganosiloxane.

[0010] As used herein, the term "silicone content" means the total amount of silicone in the dispersed phase of the dispersion or emulsion, from whatever source, including, but not limited to a siloxane polymer or siloxane polymer mixtures, a self-catalyzing crosslinking agent, a in situ resin reinforcers, and/or silane or polymeric silane stabilizers.

[0011] As used herein, the term "portion" means any amount from 1 % to 100%, 1 % to 90%, 1 % to 80%, 1 % to 70%, 1 % to 60%, 1 % to 50%, 1 % to 40%, 1 % to 30%, 1 % to 20%, 1 % to 10% or 1 % to 5% of a component. For example, a portion may mean 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or 1 %.

[0012] As used herein, the term "nonionic surfactant" means a nonionic surfactant that is not polyvinyl alcohol of compounds derived from polyvinyl alcohol.

[0013] The siloxane polymers. The siloxane polymers or polymer mixtures used as starting materials comprises linear or branched siloxane polymers having at least two reactive groups per polymer, and may be characterized as having a viscosity of greater than 100 mPa^«s but less than 25,000,000 mPa^«s, or alternatively from 1000 mPa^«s - 15,000,000 mPa-s, or alternatively from 5000 mPa-s - 10,000,000 mPa-s, or alternatively from 10,000 mPa^«s - 5,000,000 mPa^«s, or alternatively from 40,000 mPa^«s - 2,000,000 mPa^«s, or alternatively from 40,000 mPa^«s - 1 ,000,000 mPa^«s, or alternatively 40,000 mPa^«s - 100,000 mPa^«s, or alternatively from 50,000 mPa^«s - 90,000 mPa^«s. In the various embodiments of the present invention, the term "siloxane", "siloxane polymer" or "siloxane polymer mixture" means or is used interchangeably with or comprises "polyorganosiloxane or a mixture of polyorganosiloxanes".

[0014] In one embodiment, the siloxane polymer or polymer mixture comprises a polyorganosiloxane or a mixture of polyorganosiloxanes having the following molecular formula (I):

X3_-nR_n-YO-(Rl ₂SiO)_z-Y-R_nX_3-n (I)

wherein

n is 0, 1 , 2 or 3 and z is an integer from 10 to 2,500,000;

X is a reactive group selected from the group consisting of hydrogen, a hydroxyl group, a condensable and a hydrolyzable group;

Y is a Si atom or a Si-(CH2)_m-SiR¹2 group wherein m is an integer from 1 to 8;

R is individually selected from the group consisting of aliphatic, alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl organic, or aromatic aryl groups; and

R¹ is individually selected from the group consisting of X, aliphatic, alkyl, alkenyl, and aromatic groups.

[0015] The polyorganosiloxane may be a single polyorganosiloxane represented by formula (I) or mixtures of polyorganosiloxanes represented by formula (I), or

solvent/polyorganosiloxane mixtures, wherein the polyorganosiloxane in the

solvent/polyorganosiloxane mixture is meant to include any of the polyorganosiloxane or mixtures of polyorganosiloxane according to formula (I).

[0016] In formula (I), each X is a reactive group that is the same or different, and is selected from the group consisting of a hydrogen, hydroxyl group, a condensable group and a hydrolyzable group. The term "hydrolyzable group" means any group attached to the silicon which is hydrolyzed by water at room temperature. The hydrolyzable group includes hydrogen, halogen atoms such as F, CI, Br or I ; groups of the formula -OT when T is any hydrocarbon or halogenated hydrocarbon group such as methyl, ethyl, isopropyl, octadecyl, allyl, hexenyl, cyclohexyl, phenyl, benzyl, beta-phenylethyl, any hydrocarbon ether radical such as 2-methoxyethyl, 2-ethoxyisopropyl, 2-butoxyisobutyl, p-methoxyphenyl or - (CH2CH20)2CH3; or any Ν,Ν-amino radical such as dimethylamino, diethylamino, ethylmethylamino, diphenylamino, or dicyclohexylamino. The X group may also be any amino radical such as NH2, dimethylamino, diethylamino, methylphenylamino or dicyclohexylamino; any ketoxime radical of the formula -ON=CM2 or -ON=CM' in which M is any monovalent hydrocarbon or halogenated hydrocarbon radical such as those shown for T above and M' is any divalent hydrocarbon radical both valences of which are attached to the carbon, such as hexylene, pentylene or octylene; ureido groups of the formula - N(M)CONM"2 in which M is defined above as a hydrocarbon radical such as those shown for T above and M" is H or any of the M radicals; carboxyl groups of the formula -OOCMM" in which M and M" are defined above or halogenated hydrocarbon radical as illustrated for T above, or carboxylic amide radicals of the formula -NMC=0(M") in which M and M" are defined above. The X group may also be a sulfate group or sulfate ester group of the formula -OS02(OM) where M is defined above as hydrocarbon or halogenated hydrocarbon radical illustrated for T; a cyano group; a isocyanate group; or a phosphate group or phosphate ester group of the formula -OPO(OM)2 in which M is defined above.

[0017] In one embodiment, X is a hydroxyl groups or alkoxy groups. Illustrative examples of the alkoxy groups are methoxy, ethoxy, propoxy, butoxy, isobutoxy, pentoxy, hexoxy, 2- ethylhexoxy, and the like; alkoxy radicals such as methoxymethoxy, ethoxymethoxy, and the like; and alkoxyaryloxy such as ethoxyphenoxy and the like. In one embodiment, the alkoxy groups are methoxy or ethoxy.

[0018] In one embodiment, the R group may individually be methyl, ethyl, octyl, vinyl, allyl, or phenyl. In one embodiment, the group may individually be selected from the group consisting of methyl, ethyl, octyl, trifluoropropyl, vinyl, and phenyl groups.

[0019] In some embodiments, the polyorganosiloxane of formula (I) may have an average of more than two condensable or hydrolyzable groups per molecule that are self-catalytic, and such a situation it is not necessary that the crosslinking agent be self-catalytic in order to form a crosslinked polyorganosiloxane. The condensable or hydrolyzable groups on different polyorganosiloxane molecules may react with each other to form crosslinks that do not involve the crosslinking agent.

[0020] The polyorganosiloxane may be a mixture of different kinds of molecules, for example long chain linear molecules and short chain linear or branched molecules. These molecules may react with each other to form a crosslinked network. Such polyorganosiloxanes which may function similar to the crosslinking agent are illustrated by low molecular weight organosilicon hydrides, such as polymethylhydrogensiloxane, low molecular weight copolymers containing methylhydrogensiloxy and dimethylsiloxy groups, - (OSi(OEt)₂-, ethylpolysihcate, (OSiMeC₂H₄Si(OMe)₃)4, and (OSi-MeON=CR'₂)4, where Me is methyl and Et is ethyl.

[0021] The polyorganosiloxane polymer of the present invention, thus, more advantageously also comprises mixtures of polyorganosiloxane polymers of formula (I), exemplified by, but not limited to, mixtures of α,ω-hydroxysiloxy terminated polyorganosiloxanes and of α,ω- bis(triorganosiloxy) terminated polyorganosiloxanes, mixtures of α,ω-hydroxylsiloxy terminated polyorganosiloxanes and of a-hydroxy, ω-triorgano-siloxy terminated

polyorganosiloxanes, mixtures of α,ω-dialkoxysiloxy terminated polyorganosiloxanes and of α,ω-triorganosiloxy terminated polyorganosiloxanes, mixtures of α,ω-dialkoxysiloxy terminated polyorganosiloxanes and of α,ω-hydroxysiloxy terminated polyorganosiloxanes, mixtures of α,ω-hydroxysiloxy terminated polyorganosiloxanes and of α,ω-triorganosiloxy terminated poly(diorgano)(hydrogenorgano)siloxane co-polymers.

[0022] The polyorganosiloxane polymer of the invention can also comprise mixtures of polyorganosiloxane polymers of formula (I) as described above with liquid, branched methylpolysiloxane polymers ("MDT fluids") comprising a combination of recurring units of the formulae:

(CH₃)₃Sio.5 ("M")

(CH₃)2SiO ("D")

CHaSiOLs C ')

and containing from 0.1 to 8% hydroxyl groups. The fluids may be prepared by co- hydrolysis of the corresponding chloro- or alkoxysilanes, as described in U.S. Pat. Nos. 3,382,205; 3,661 ,817; 3,714,089; 4,356,1 16;4,468,760; 5,175,057 and Belgian Patent No. 0,877,267, which patents are incorporated herein by reference. The proportion of MDT fluids added should not exceed 50 parts, preferably of 1 to 20 parts by weight, per 100 parts by weight of the polyorganosiloxane polymer of formula (I), in order to achieve improved physical properties and adhesion of the resultant polymers. The polyorganosiloxane polymer of the present invention may also comprise mixtures of polyorganosiloxane polymers of formula (I) with liquid or solid, branched methylsiloxane polymeric resins comprising a combination of recurring units of the formulae:

(CH₃)₃Sio.5 ("M")

(CH₃)2SiO ("D")

CHaSiOLs C ') Si0₂ ("Q")

and containing from 0.1 to 8% hydroxyl groups, the fluids may be prepared by co-hydrolysis of the corresponding chloro- or alkoxysilanes, as described in U.S. Pat. Nos. 2,676,182; 2,441 ,320; 4,707,531 ; 5,070,175; EP 0,529,547; 0,535,687; DE 4,124,588; JP 05,098,012; WO 93/23455, which patents are incorporated herein by reference. The MDTQ fluid/resin may be added in a proportion not exceeding 50 parts, preferably of 1 to 10 parts by weight, per 100 parts by weight of the polymer of formula (I) to improve physical properties and adhesion of the resultant polymers. The MDTQ fluids/resins can also be mixed with MDT fluids and the polyorganosiloxane polymers of formula (I). Finally the polyorganosiloxane polymer may comprise mixtures of polyorganosiloxane polymers of formula (I) with compatible organic solvents, to form organic polymer/solvent mixtures. These organic solvents are exemplified by, but not limited to, organophosphate esters, such as

trioleylphosphate, trioctylphosphate, or tetraethyleneglycolmonolauryletherphosphate, as disclosed in U.S. Pat. No. 4,147,855 and German Patent No. 2,802,170 (incorporated by reference); alkanes, such as hexane, heptanes; and higher paraffines, aromatic solvents, such as toluene, benzene; etc. The polymer solvent mixtures can also be added with MDT fluids and/or MDTQ fluids to the polyorganosiloxane polymer of formula (I). Any of the above mixtures of polymers or polymer/solvents can be prepared by mixing the ingredients prior to emulsification or by emulsifying them individually and then mixing into the final emulsion.

[0023] Polyvinyl alcohol polymer. The polyvinyl alcohol (PVA) polymer may in general be any PVA useful for dispersing the siloxane, crosslinked siloxane, polyorganosiloxane or crosslinked polyorganosiloxane. The PVA may be any commercially available polyvinyl alcohol and may for example have a degree of hydrolysis in the range 75% to 99%, alternatively 80% to 99%, alternatively 85% to 99%, alternatively 90% to 99%, alternatively 80% to 95%, or alternatively 85% to 95%. The viscosity of the PVA, measured as the viscosity of a 4% w/w aqueous solution at 20 °C determined by Hoppler viscometer (DIN 53015), can for example be in the range 3 to 60 mPa-s. Various suitable PVAs are sold by

Kuraray America Inc. under the trademark Mowiol®, for example, Mowiol® 18-88, Mowiol® 8-88, Mowiol® 30-88, Mowiol® 30-92 and Mowiol® 20-98. Various suitable PVAs are also available from DuPont Inc. under the trademark Elvanol®. Polyvinyl alcohol polymer is also sold under the tradename Kuraray POVAL™, for instance, Kuraray POVAL™ 30-92, Kuraray POVAL™ 20-98, Kuraray POVAL™ 8-88, Kuraray POVAL™ 18-88, and Kuraray POVAL™ 40-88. Polyvinyl alcohol polymer is also sold under the tradename EXCEVAL™. The polyvinyl alcohol polymer may be a fully saponified grade, partially saponified grade, ultra low saponified grade, defoamed grade, fine powder grade and low ash grade. [0024] The polyvinyl alcohol polymer works as a surfactant to emulsify and as a stabilizing agent to stabilize the siloxane dispersion or emulsion. For example, the polyvinyl alcohol polymer enhances stability against coalescing solvents. Coalescing solvents, include, but are not limited to, organic solvents, esters, and alcohols. Examples of alcohols include, but are not limited to, isopropyl alcohol, n-propanol, or ethanol. The emulsifying and stabilizing properties of the polyvinyl alcohol polymer in the present invention are unexpected advantages that are not exhibited by commonly used non-ionic, cationic, or anionic surfactants.

[0025] In one embodiment, the present invention provides methods for making a crosslinked polyorganosiloxane emulsion, the methods comprising preparing a mixture by combining polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups, a self -catalyzing crosslinking agent having more than two leaving groups, a polyvinyl alcohol polymer, and water, and then emulsifying in the presence of the PVA. The PVA helps to disperse the crosslinked polyorganosiloxane in a continuous aqueous phase. The PVA may be used as an aqueous solution.

[0026] The concentration of PVA in the emulsion may be 0.1 to 25%, 0.1 to 20%, 0.1 to 15%, 0.1 to 10%, 0.1 to 5%, 0.1 to 2%, 0.1 to 1 %, 0.5 to 10%, 0.5 to 8%, 0.5 to 5%, 0.5 to 3%, 0.5 to 2%, 0.5 to 1 %, 1 to 10%, 1 to 8%, 1 to 5%, 1 to 3%, or 1 to 2%, based on the weight of the emulsion.

[0027] At low amounts of PVA, for example, below 15% based on the weight of the emulsion, a non-Newtonian "thick phase" is formed, which is much more viscous at low shear rate than the siloxane polymer alone and often exhibits a yield stress (viscoplastic behaviour). Formation of such a thick phase allows more thorough mixing of the hydrophobic components with the aqueous phase and thus aids in the formation of the emulsion. In the initial stage of the emulsification, the amount of PVA in the emulison may be below 15% as defined above for formation of a thick phase. In the thick phase, the amount of PVA may be 0.2 to 50% by weight of the emulsion. In some embodiments, only a part of the PVA is used in the initial stage of the emulsification. The thick phase may be diluted with water or with further PVA to form a less viscous emulsion.

[0028] The PVA:siloxane weight ratio may be from 0.1 :100 to 25:100, or 0.1 :100 to 20:100, or 0.1 :100 - 15:100, or 0.5:100 - 10:100, or 1 :100 - 5:100. Alternatively, the PVA may be 0.1 %, 0.5%, 1 %, 2%, 5%, 10%, 15%, or 20% by weight of the siloxane.

[0029] The emulsions of the present invention includes a predetermined amount of water. The water is present in the emulsion in an amount of from 0.5 to 90% by weight of emulsion, or from 0.5 to 80% by weight of emulsion, or from 0.5 to 70% by weight of emulsion, or from 0.5 to 60% by weight of emulsion, or from 0.5 to 50% by weight of emulsion, or from 0.5 to 40% by weight of emulsion, or from 2 to 90% by weight of emulsion, or from 2 to 80% by weight of emulsion, or from 2 to 70% by weight of emulsion, or from 2 to 60% by weight of emulsion, or from 2 to 50% by weight of emulsion, or from 2 to 40% by weight of emulsion, or from 5 to 90% by weight of emulsion, or from 5 to 80% by weight of emulsion, or from 5 to 70% by weight of emulsion, or from 5 to 60% by weight of emulsion, or from 5 to 50% by weight of emulsion, or from 5 to 40% by weight of emulsion. Water in an amount less than 2 % by weight of the emulsion may be used to achieve desirable results.

[0030] In some embodiments, the aqueous silicone emulsion comprise from 10 to 200 parts by weight of water per 100 parts of the siloxane, or from 10 to 180 parts by weight of water per 100 parts of the siloxane, or from 10 to 160 parts by weight of water per 100 parts of the siloxane, or from 10 to 140 parts by weight of water per 100 parts of the siloxane, or from 10 to 120 parts by weight of water per 100 parts of the siloxane, or from 10 to 100 parts by weight of water per 100 parts of the siloxane, or from 10 to 80 parts by weight of water per 100 parts of the siloxane, or from 10 to 60 parts by weight of water per 100 parts of the siloxane, or from 10 to 40 parts by weight of water per 100 parts of the siloxane, or from 10 to 20 parts by weight of water per 100 parts of the siloxane. Water may also be added after mixing, in any amount, to dilute the gel phase.

[0031 ] Self-catalyzing crosslinkinq agent. At least one self -catalyzing crosslinking agent is present in the reaction mixture or composition. The self-catalyzing crosslinking agent may be in an amount from 0.01 to 60 parts by weight, 0.01 to 50 parts by weight, 0.01 to 40 parts by weight, 0.01 to 30 parts by weight, 0.01 to 20 parts by weight, or 0.01 to 10 parts by weight, 0.01 to 5 parts by weight, 0.5 to 60 parts by weight, 0.5 to 50 parts by weight, 0.5 to 40 parts by weight, 0.5 to 30 parts by weight, 0.5 to 20 parts by weight, or 0.5 to 10 parts by weight, 0.5 to 5 parts by weight, 1 to 60 parts by weight, 1 to 50 parts by weight, 1 to 25 parts by weight, 1 to 15 parts by weight, or 1 to 5 parts by weight per 100 parts of siloxane polymer.

[0032] The term "self-catalyzing crosslinking agent" or "self-catalytic crosslinking agent" means a molecule that has at more than two leaving groups and does not require a separate species as a catalyst. While in certain circumstances only one self-catalytic crosslinking agent may be needed to produce an elastomer having the desired physical properties, those skilled in the art will recognize that two or more self-catalytic crosslinking agents may be added to the reaction mixture to achieve desirable results. In addition, the self-catalytic crosslinking agent or crosslinking agent may be added with a conventional catalyst.

However, adding the self-catalytic crosslinking agent with a conventional catalyst is not required for the practice of this invention, and the compositions contemplated by this invention may in fact be free of said conventional catalysts. [0033] Typical self-catalytic crosslinking agents include tri or tetra functional compounds, such as R-Si-(Q)3 or Si-(Q)4, where Q is carboxylic, OC(0)R, e.g., acetoxy and R is an alkyl group of 1 to 8 carbon atoms inclusive, preferably methyl, ethyl or vinyl. Other preferred Q groups are the hydroxyl amines, ON(R)2, where R is the same or different alkyl group of 1 to 8 carbon atoms inclusive, e.g., ON(CH2CH3)2. Q may also be an oxime group, such as O-

N=C(R)2 where R is the same or different alkyl group of 1 to 8 carbon atoms inclusive, e.g.,

0-N=C(CH3)(CH2CH3). Further, Q may be an amine group such as N(R)2 where R is the same or different alkyl group of 1 to 8 carbon atoms inclusive or cyclic alkyl group of 5 to 10 carbon atoms inclusive, e.g., N(CH3)2 or NH(cyclohexyl). Finally, Q may be an acetamido group, NRC(0)R, where R is the same or different alkyl group of 1 to 8 carbon atoms inclusive, e.g., Ν(ΟΗ₃)0(0)ΟΗ₃.

[0034] In addition, partial hydrolysis products of the aforementioned compounds may also function as self-catalytic crosslinking agents. This would include dimers, trimers, tetramers etc., for example compounds of the formula:

Q Q

R-Si-0--Si-R

Q Q

where Q and R are defined in the preceding paragraph.

[0035] Also useful as self-catalytic crosslinking agents are those polymeric or copolymeric species containing more than two Q sites located at either pendant or terminal positions or both on the backbone of a polydiorganosiloxane molecule. Examples of the pendent group include compositions of the following formula:

R₃SiO(R₂SiO)_a(RSiO)bSiR3

ON(CH₂CH₃)₂

where R is the same or different alkyl group of from 1 to 8 carbon atoms inclusive, and a is 0 or more, and b is greater than 2. In some embodiments, a is 0 - 100, or 0 - 80, or 0 - 60, or 0 - 40, or 0 - 20, or 0 - 10, or 0 - 5. In some embodiments, b greater than 2 up to 100, or 3 - 90, or 3 - 70, or 3 - 50, or 3 - 30, or 3 - 10, or 3 - 5. In general polymeric compositions having either pendent or terminal Q groups may be used in the practice of the present invention. In one embodiment, self-catalyzing crosslinking agent comprises compounds of the general formula:

Q3_-nR_nSiO(R₂SiO)_zSiR_nQ_3-n

where

n is 0, 1 , 2, or 3;

z is a positive integer; and R is Q, or independently the same or different alkyl chain of 1 to 8 carbon atoms inclusive as long as there are more than two Q groups on the molecule. Q is as defined above.

[0036] In one embodiment, the self-catalying crosslinking agent comprises a compound of general formula:

R₃SiO(R₂SiO)_a(RSiO)bSiR3 ON(CH₂CH₃)₂

where R is the same or different alkyl group of from 1 to 4 carbon atoms inclusive, and a is 0 - 5, and b is 3 - 10. In one embodiment, R is methyl or ethyl, a is 2 or 3 or 4 and b is 3 or 4 or 5 or 6. In another embodiment, R is methyl, and a is 2 and b is 5.

[0037] Effective self-catalytic crosslinking agents are those compounds which form elastomers when mixed with functional silicone polymers in the absence of additional catalysts such as tin carboxylates or amines. In the self-catalytic crosslinking agent, the acetoxy, oxime, hydroxyl amine (aminoxy), acetamide and amide groups catalyze the formation of Si-O-Si bonds in reactions of the type contemplated by this invention.

[0038] One skilled in the art would recognize that the starting polymer itself could be pre- endblocked with self-catalytic crosslinking moieties. Optionally further self-catalytic crosslinking agent can be added to such compositions.

[0001] Crosslinked polvorqanosiloxane. The crosslinked polyorganosiloxane may be described as a plurality of particles. The crosslinked polyorganosiloxane may be a solid, liquid, or elastomer (having both solid and liquid properties). In one embodiment, the crosslinked polyorganosiloxanes are silicone elastomers. The crosslinked

polyorganosiloxane comprises a type of tri-dimensional crosslinked silicone polymers. For example, the crosslinked polyorganosiloxane may be further defined as silicone elastomer that is not dissolvable in an organic solvent or water. The silicone elastomer may be minimally soluble or swellable in one or more organic solvents.

[0002] The crosslinked polyorganosiloxane are not particularly limited in size or shape. Typically, the crosslinked polyorganosiloxane are approximately spherical or oval shaped. The crosslinked polyorganosiloxane may have an average diameter (or a distribution of average diameters) of from 1 to 1000, 1 to 500, 1 to 450, 1 to 400, 1 to 350, 1 to 300, 1 to 250, 1 to 200, 1 to 150, 1 to 100, 100 to 500, 150 to 450, 200 to 400, 250 to 350, 300 to 350, 5 to 95, 10 to 90, 15 to 85, 20 to 80, 25 to 75, 30 to 70, 35 to 65, 40 to 60, 45 to 55, 50 to 55, 1 to 20, 2 to 19, 3 to 18, 4 to 17, 5 to 16, 6 to 15, 7 to 14, 8 to 13, 9 to 12, 10 to 1 1 , 1 to 10, 2 to 9, 3 to 8, 4 to 7, 5 to 6, 50 to 70, 55 to 65, or 60 to 65 microns. In other embodiments, the particles have an average diameter or distribution of average diameters from 10 to 100 nm, from 0.1 to 1 ,000 micrometers, or from 1 ,000 to 5,000, micrometers. The average diameter of the particles may be determined using a Malvern Mastersizer^® S. In additional embodiments, any value, or range of values, both whole and fractional, within or between any one or more values described above are contemplated.

[0003] The crosslinked polyorganosiloxane, or its emulsion, slurry, and/or dispersion may be utilized in any product for coatings in cosmetics, in paints, in textiles, and personal care.

[0039] The crosslinked polyorganosiloxane may form a film. The film is not particularly limited any may have any dimensions of length, width, and thickness. In various embodiments, the film has a thickness of from 10 to 100 nm, from 0.1 to 1 ,000 micrometers, or from 1 ,000 to 5,000, micrometers.

[0040] The aqueous silicone emulsion of the present invention may have the a crosslinked polyorganosiloxane or silicone content of from 1 % to 98% by weight of the emulsion, or from 40% to 90% or 50% to 70% by weight of the emulsion.

[0041] Optional components. The emulsions of the present invention may have an optional co-surfactant. Co-surfactants may be selected from nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants or mixtures thereof. The co- surfactant may be present in the emulsions in an amount of 0.1 to 25 parts by weight of siloxane polymer, and is preferably present in the amount of 1 to 10 parts by weight of siloxane polymer. Co-Surfactant in an amount less than 3 parts by weight of siloxane polymer may also be used to achieve desirable results. To those skilled in the art, co- surfactants may be useful to enhance properties such as freeze/thaw stability, high temperature stability, or clarity of the resulting elastomer film.

[0042] Selection of the co-surfactant may have an important impact on the properties of the dispersion or the elastomer resulting after the evaporation of water. The properties particularly controllable by co-surfactant selection are freeze/thaw stability, high temperature heat stability and clarity.

[0043] In situ resin reinforcers such as methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl orthosilicate (TEOS), normal propylorthosilicate (NPOS) may be added as an optional component. Such resin reinforcers helps to improve the physical properties of an elastomer, particularly the tensile, elongation and hardness properties. It also results in improved clarity of the resulting elastomer.

[0044] Aminosilanes containing polymeric or neat aminosilanes may also be added as optional components. Neat aminosilanes include compounds of the formula:

(RO)_3-nR_nSiQ NR_yH_2-y

where:

n and y are independently 0, 1 , or 2,

R is the same or different alkyl chain of 1 to 8 carbon atoms inclusive, could be (CH2)_Z or {(CH2)_ZN(R)}_W, where z is an integer from 1 to 10, and w is from 0 to 3 inclusive.

[0045] Polymeric amino silanes may also be used as optional components in the practice of the present invention, such as reaction products of silanol functional siloxane fluids and aminosilanes, or silanol functional siloxane fluids and alkoxysilanes and aminosilanes. For example, one useful polymeric amino siloxane has the formula:

(MeO)2MeSiO(Me₂SiO)_zSi(OMe)2 i CH₂)3NH(CH₂)2NH₂

where z is from 3 to 40.

[0046] Fillers may be optionally added to the composition of the invention, such as colloidal silica, silica powders made by combustion and precipitation, semi-reinforcing agents such as diatomaceous earths, ground quartz, etc. Nonsiliceous fillers may also be added, such as calcium carbonate, hydrated alumina, magnesium hydroxide, carbon black, titanium dioxide, aluminum oxide, vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulfate, slaked lime, etc. If necessary, liquid alkoxy silanes which are soluble in the siloxane polymer may be added with the filler to compatibilize the filler with the siloxane polymers.

[0047] It should be noted that selection and addition to the composition of particular fillers, such as certain types of silicas, may improve the physical properties of the resulting elastomer, particularly tensile properties, elongation properties, hardness, and heat stability. Elastomers containing ammonium stabilized silicas are heat stable while sodium stabilized silicas are not. Acidic silicas, (those containing H+ as a stabilizer) also yield heat stable elastomers. In general, colloidal or dispersed silica which is not stabilized by Group IA or 11 A elements yield heat stable elastomers. Volatile organic amines and volatile inorganic bases are expected to be useful stabilizers for silicas that would yield heat stable elastomers, e.g., (R)3_-XN(H)_X where x=0, 1 , 2, or 3, R is an alkyl or aryl group such as (CH3)2NH, or R is an alcohol group such as N(CH2CH20H)3 or NH(CH2CH20H)2. The volatile organic amines include cyclohexylamine, triethylamine, dimethylaminomethylpropanol, diethylaminoethanol, aminomethyl propanol, aminobutanol, monoethanolamine, monoisopropanolamine, dimethylethanolamine, diethanolamine, aminoethylpropanediol, aminomethylpropanesiol, diisopropanolamine, morpholine, tris(hydroxymethyl)aminomethane, triisoproanolamine, triethanolamine, aniline, urea.

[0048] In addition to the volatile organic amines, volatile inorganic bases such as ammonia and ammonium carbonate also yield heat stable elastomers.

[0049] In one embodiment, an aqueous silicone emulsions of the present invention are useful as slip additives in organic coatings. Slip additives provide a low coefficient of friction (CoF) for coatings which leads to improved abrasion resistance. The emulsion is prepared via a self-crosslinking reaction of an aminoxy-functional siloxane crosslinking agent and a siloxane polymer, which are emulsified in the presence of polyvinyl alcohol. The polyvinyl alcohol imparts a degree of stability to the aqueous emulsions which is not observed with conventional surfactants, such as nonionic surfactants. Particularly, the slip additives according to the present invention possess good stability in water-based coatings that contain alcohols and/or coalescing solvents. Alcohols and/or coalescing solvents destabilize silicone emulsions prepared with conventional nonionic, cationic, anionic, or amphoteric surfactants.

[0050] In one embodiment, the emulsions of the present invention are silicone water-based elastomer (SWBE) that uses polyvinyl alcohol (PVA) as a surfactant. Polyvinyl alcohol provides advantageous feature to the emulsions, such as, but no limited to, stability towards coalescing solvents or alcohols that are used in numerous water-based coatings. Emulsions of silicones prepared with conventional surfactants such as alcohol ethoxylates or polyoxyalkylene copolymers (Pluronic® surfactants) are not so stable in some organic water- based coatings that contain certain coalescing solvents or alcohols. In contrast, the emulsions described by the present invention are stable in such compositions and the stability is achieved by the presence of PVA. In addition to possessing good stability in numerous coatings compositions, the silicone emulsion of the present invention also provides excellent slip properties to the dried coating films.

[0051] The present invention also provides methods for making a crosslinked

polyorganosiloxane emulsion, the method comprising:

A. combining components:

i. polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two hydrolyzable groups, ii. at least one self-catalyzing crosslinking agent having more than two leaving groups,

iii. a polyvinyl alcohol polymer, and

iv. water;

polyorganosiloxane emulsion

[0052] The siloxane polymer and the self-catalyzing crosslinking agent are mixed. Water and PVA are then added to the siloxane polymer and self -catalyzing crosslinking agent and the composition is mixed until a high solids gel phase is formed. Any type of mixing equipment may be used including mixing devices, equipped with disperser blades such as a Cowles™ blade. The gel will have a silicone content of at least 85%.

[0053] Emulsification is generally carried out in a high shear mixer, for example a rotor and stator mixer. The particle size of the emulsion can be reduced in a subsequent step if desired, for example in an apparatus applying increased shear such as a homogeniser or Microfluidiser^® high pressure processor, or a Sonolator™ homogenizer (ultrasonic mixer), producing an emulsion in which the volume median diameter of the droplets is in the range 0.3 to 30μιη (micrometres).

[0054] After mixing, the gel may be diluted with water to the desired silicone content. The dispersion or emulsion may be stored for long periods of time. The dispersion or emulsion may then be dispensed, and will form an elastomeric film upon the evaporation of water.

[0055] The emulsions of the present invention may have an average volume particle size from 0.2 to 1000 μιη, alternatively from 0.2 to 500 μιη, alternatively from 0.2 to 100 μιη, alternatively from 0.2 to 50 μιη, alternatively from 0.2 to 30 μιη, alternatively from 0.2 to 20 μιη, alternatively from 0.2 to 10 μιη, alternatively from 1 to 10 μιη.

[0056] The particle size may be determined by laser diffraction of the emulsion. Suitable laser diffraction techniques are well known in the art. The particle size is obtained from a particle size distribution (PSD). The PSD can be determined on a volume, surface, length, or number basis. The volume particle size is equal to the diameter of the sphere that has the same volume as a given particle. The term Dv, as used herein, represents the average volume particle size of the dispersed particles. Dv50 is the particle size measured in volume corresponding to 50% of the cumulative particle population. In other words, if Dv50 = 10 μιη, 50% of the particle have an average volume particle size below 10 μιη and 50% of the particle have a volume average particle size above 10 μιη. Dv90 is the particle size measured in volume corresponding to 90% of the cumulative particle population. In these instances a Malvern-Mastersizer® 2000 may be used to obtain particle size distributions in the range 0.5 to 1000 μιη, while a Microtrac-Nanotrac® may be used to measure particle size distributions in the ranges less than 0.5 μιη.

[0057] Those skilled in the art will recognize that the emulsions of the present invention may be prepared in other ways. For instance, the siloxane polymer and the self-catalyzing crosslinking agent mixture may be added to a surfactant and water solution and then emulsified using colloid mills, homogenizers, sonolaters or other high shear devices as described in U.S. Pat. No. 5,037,878 and U.S. Pat. No. 5,034,455.

[0001] The dispersion or emulsion may be formed by either a batch process, as described above, or a continuous process. If a continuous process is used, then a low shear dynamic mixer or static mixer is preferred.

[0002] The following additional embodiments further illustrate the present invention. [0003] Embodiment 1 . An aqueous silicone emulsion comprising a crosslinked

polyorganosiloxane, a polyvinyl alcohol polymer, and water, wherein the crosslinked polyorganosiloxane is a reaction product of (A) a polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups and (B) at least one self-catalyzing crosslinking agent having more than two leaving groups.

[0004] Embodiment 2. The aqueous silicone emulsion of claim Embodiment 1 , wherein the emulsion has a silicone content of from 1 % to 98% by weight of the emulsion.

[0005] Embodiment 3. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion has a silicone content of from 40% to 90% or 50% to 70% by weight of the emulsion.

[0006] Embodiment 4. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein 0.1 to 25 parts by weight of the polyvinyl alcohol polymer is present per 100 parts of polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

[0007] Embodiment 5. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein 0.5 to 5 parts by weight of the polyvinyl alcohol polymer is present per 100 parts of the polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

[0008] Embodiment 6. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein 10 to 200 parts by weight of water is present per 100 parts of the polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

[0009] Embodiment 7. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein 0.01 to 50 parts by weight of self-catalyzing crosslinking agent is present per 100 parts of the polyorganosiloxane polymer or a mixture of

polyorganosiloxanes.

[0010] Embodiment 8. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the at least one leaving groups of the self-catalyzing crosslinking agent is selected from the group consisting of acetoxy, amide, acetamide, aminoxy and oxime.

[0011] Embodiment 9. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the self -catalyzing crosslinking agent is of formula

R₃SiO(R₂SiO)a(RSiO)_bSiR3 ON(CH₂CH₃)₂

where R is the same or different alkyl group of from 1 to 8 carbon atoms inclusive, a is 0 - 100, and b greater than 2 up to 100.

[0012] Embodiment 10. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion further comprises a stabilizer of formula: (MeO)2MeSiO(Me₂SiO)_zSi(OMe)2

(CH₂)3NH(CH₂)2NH2

where Me is a methyl group, and z is an integer from 3 to 40 inclusive.

[0013] Embodiment 12. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion further comprises an in situ resin reinforcer selected from the group consisting of methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl orthosilicate, and normal propylorthosilicate.

[0014] Embodiment 13. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion further comprises a nonionic surfactant, cationic surfactant, anionic surfactant, or amphoteric surfactant.

[0015] Embodiment 14. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion further comprises a filler.

[0016] Embodiment 15. The aqueous silicone emulsion of Embodiment 14, wherein the filler is silica.

[0017] Embodiment 16. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the emulsion comprises a siloxane phase comprising the crosslinked polyorganosiloxane and the siloxane phase has a first refractive index, and the emulsion comprises an aqueous phase comprising the polyvinyl alcohol polymer and a portion of the water and the aqueous phase has a second refractive index, and the first refractive index is substantially the same as the second refractive index.

[0018] Embodiment 17. The aqueous silicone emulsion of any of the preceding

Embodiments, wherein the polyorganosiloxane or a mixture of polyorganosiloxanes comprises hydroxy terminated polydiorganosiloxane.

[0019] Embodiment 18. A method for making a crosslinked polyorganosiloxane emulsion, the method comprising:

A. combining components:

iii. a polyvinyl alcohol polymer, and

iv. water;

B. mixing the components at a high shear to form an aqueous emulsion having a dispersed phase comprising components i and ii; and C. reacting the polyorganosiloxane or a mixture of polyorganosiloxanes and the at least one self -catalyzing crosslinking agent to obtain a crosslinked

polyorganosiloxane emulsion.

[0020] Embodiment 19. The method of Embodiment 18, wherein the crosslinked polyorganosiloxane emulsion has a silicone content of from 1 % to 98% by weight of the emulsion.

[0021] Embodiment 20. The method of any one of Embodiments 18 to 19, wherein the crosslinked polyorganosiloxane emulsion has a silicone content of from 40% to 90% or 50% to 70% by weight of the emulsion.

[0022] Embodiment 21 . The method of any one of Embodiments 18 to 20, wherein 0.1 to 25 parts by weight of the polyvinyl alcohol polymer is present in the crosslinked

polyorganosiloxane emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

[0023] Embodiment 22. The method of any one of Embodiments 18 to 21 , wherein 0.5 to 5 parts by weight of the polyvinyl alcohol polymer is present in the emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

[0024] Embodiment 23. The method of any one of Embodiments 18 to 22, wherein 10 to 200 parts by weight of water is present in the emulsion per 100 parts of the

polyorganosiloxane or a mixture of polyorganosiloxanes.

[0025] Embodiment 24. The method of any one of Embodiments 18 to 23, wherein 0.01 to 50 parts by weight of self-catalyzing crosslinking agent is present in the emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

[0026] Embodiment 25. The method of any one of Embodiments 18 to 24, wherein the least one catalytic leaving group of the self-catalyzing crosslinking agent is selected from the group consisting of acetoxy, amide, aminoxy, acetamine and oxime.

[0027] Embodiment 26. The method of any one of Embodiments 18 to 25, wherein the self- catalyzing crosslinking agent is

R₃SiO(R₂SiO)_a(RSiO)_bSiR3

ON(CH₂CH₃)₂

[0028] Embodiment 27. The method of any one of Embodiments 18 to 26, comprising the additional step of adding before or after the mixing step, a stabilizer of the formula:

(MeO)2MeSiO(Me₂SiO)_zSi(OMe)2

(CH₂)₃NH(CH₂)₂NH₂ where Me is a methyl group, and z is an integer from 3 to 40 inclusive.

[0029] Embodiment 28. The method of any one of Embodiments 18 to 28, comprising the additional step of adding before or after to mixing an in situ resin reinforcer selected from the group consisting of methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl orthosilicate, and normal propylorthosilicate.

[0030] Embodiment 29. The method of any one of Embodiments 18 to 28, comprising the additional step of adding a filler either before or after mixing.

[0031] Embodiment 30. The method of any one of Embodiments 18 to 29, wherein the filler is silica.

[0058] Embodiment 31 . The method of any one of Embodiments 18 to 30, wherein the emulsion comprises a siloxane phase comprising the crosslinked polyorganosiloxane and the siloxane phase has a first refractive index, and the emulsion comprises an aqueous phase comprising the polyvinyl alcohol polymer and a portion of the water and the aqueous phase has a second refractive index, and the first refractive index is substantially the same as the second refractive index.

[0059] Having described the invention with reference to certain embodiments, other embodiments will become apparent to one skilled in the art from consideration of the specification. The invention is further defined by reference to the following examples describing the preparation of the emulsions and processes of the invention. It will be apparent to those skilled in the art that many modifications, both to materials and procedures, may be practiced without departing from the scope of the invention.

EXAMPLES

[0060] The following examples are presented to further illustrate the compositions of this invention, but are not to be construed as limiting the invention, which is delineated in the appended claims.

Example 1

[0061] 50. Og of polydimethylsiloxane polymer having Si(CH3)20H chain ends and having a viscosity of approximately 80,000 centipoise was weighed into a max 100 cup followed by 1 .00g of a self-catalyzing crosslinking agent that is a dimethyl, methyl aminoxy functional polysiloxane having trimethylsiloxy units at the terminal with an average of five reactive aminoxy-functional groups per molecule and a viscosity of about 100 cP. The cup was closed and placed in a DAC-150 SpeedMixer® vortex mixer and spun for 25 seconds at maximum speed. Without delay, 6.0g of a 10 percent aqueous solution of polyvinyl alcohol (Mowiol® 30-92) was added to the cup followed by 0.51 g of deionized (Dl) water and 20g of 3mm diameter glass beads. The cup was spun for 30 seconds at maximum speed. The cup was opened and the walls of the cup were scraped and the contents of the cup were mixed quickly by hand using a spatula. The cup was closed and returned to the mixer and spun for another 30 seconds. The cup was opened and 3 g of Dl water was added followed by spinning the cup for 20 seconds at maximum speed. Next 5g of Dl water was added and the cup was spun again for 20 seconds. This was followed by an 8g aliquot of Dl water. A final 10.25g aliquot of water was added and the cup was spun for 30 seconds at maximum speed. The cup and its contents were allowed to remain undisturbed for approximately 20 hours at ambient laboratory temperature after which particle size of the emulsion was determined using a Malvern Mastersizer® S particle size instrument. Particle size was found to be Dv 50 = 3.37um; Dv90 = 6.87um, which means that 50 percent of the particles had a particle size 3.37um or less and 90 percent of the particles had a particle size of 6.87um or less. The composition consisted of an aqueous emulsion of silicone elastomer particles having a silicone content of approximately 60 percent.

[0062] A 30 percent solution of n-propyl alcohol in water was prepared by dissolving 3g of n- propanol in 7g of water in a 30ml glass vial. 2.0g of the above described emulsion was added by pipette to the solution, the cap was secured to the vial and the mixture was shaken by hand for about ten seconds to fully mix the components. The resulting mixture was homogeneous in appearance, indicating that the emulsion dispersed completely in the alcohol-water solution. Comparative Example

[0063] As a comparative experiment, an aqueous emulsion of a silicone water-based elastomer was prepared using a similar procedure described in Example 1 of US Patent 5,674,937. This comparative emulsion was the same as the emulsion of Example 1 in US Patent 5,674,937 with the exception of the surfactant. In the comparative emulsion, the surfactant was 5 parts of Tergitol ® TMN-10 alcohol ethoxylate surfactant based on polymer weight instead of 2 parts of Tergitol® TMN-6 surfactant based on polymer weight as described in US Patent 5,674,937. 2.0g of the comparative emulsion was added by pipette to a 30 per cent n-propanol solution in a 30ml glass vial and the vial was capped and shaken. A single blob of polymer formed in the alcohol solution almost immediately upon shaking, which indicated that the emulsion was unstable in the solution and had coagulated. Example 2

[0064] 50. Og of polydimethylsiloxane polymer having Si(CH₃)20H chain ends and having a viscosity of approximately 80,000 centipoise was weighed into a max 100 cup followed by 1 .05g of a self-catalytic aminoxy-functional siloxane possessing on average five reactive groups per molecule with a viscosity of about 100 cP. The cup was closed and placed in a DAC-150 SpeedMixer® vortex mixer and spun for 25 seconds at maximum speed. Without delay, 6.6g of a 15 percent aqueous solution of polyvinyl alcohol (Mowiol® 30-92) was added to the cup along with 20g of 3mm diameter glass beads. The cup was spun for 30 seconds at maximum speed. The cup was opened and the walls of the cup were scraped. The cup was closed and returned to the mixer and spun for another 30 seconds. The cup was opened and 5 g of Dl water was added followed by spinning the cup for 20 seconds at maximum speed. Four more aliquots of water were added such that the total amount of Dl water added was 44.1 g, and the cup was spun for 30 seconds at maximum speed after each addition of water. Particle size of the emulsion was determined using a Malvern

Mastersizer® 2000 particle size instrument. Particle size was found to be Dv 50 = 2.3μιη; Dv90 = 3.9μιη. The composition consisted of an aqueous emulsion of silicone elastomer particles having a silicone content of approximately 50 percent.

[0065] An aqueous solution of 2-Butoxyethanol was prepared by mixing 4.5g of Dl water with 0.5g of 2-Butoxyethanol. 5.0g of the above described silicone emulsion was added by pipette to the solution, the cap was secured to the vial and the mixture was shaken by hand for about ten seconds to fully mix the components. The resulting mixture was homogeneous in appearance, indicating that the emulsion dispersed completely in the solvent solution which had a final concentration of 5% 2-Butoxyethanol. One day after adding the emulsion to the Butoxyethanol solution, the particle size was measured again and found to be Dv 50 = 2.2μιη and Dv90 = 3.7μιη, indicating that the silicone particles are stable in the presence of 5% Butoxyethanol.

Claims

CLAIMS What is claimed is:

1 . An aqueous silicone emulsion comprising a crosslinked polyorganosiloxane, a polyvinyl alcohol polymer, and water, wherein the crosslinked polyorganosiloxane is a reaction product of (A) a polyorganosiloxane or a mixture of polyorganosiloxanes wherein the polyorganosiloxane comprises at least two reactive groups and (B) at least one self- catalyzing crosslinking agent having more than two leaving groups.

2. The aqueous silicone emulsion of claim 1 , wherein the emulsion has a silicone content of from 1 % to 98% by weight of the emulsion.

3. The aqueous silicone emulsion of any of the preceding claims, wherein the emulsion has a silicone content of from 40% to 90% or 50% to 70% by weight of the emulsion.

4. The aqueous silicone emulsion of any of the preceding claims, wherein 0.1 to 25 parts by weight of the polyvinyl alcohol polymer is present per 100 parts of

polyorganosiloxane polymer or a mixture of polyorganosiloxanes. 5. The aqueous silicone emulsion of any of the preceding claims, wherein 0.

5 to 5 parts by weight of the polyvinyl alcohol polymer is present per 100 parts of the polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

6. The aqueous silicone emulsion of any of the preceding claims, wherein 10 to 200 parts by weight of water is present per 100 parts of the polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

7. The aqueous silicone emulsion of any of the preceding claims, wherein 0.01 to 50 parts by weight of the self -catalyzing crosslinking agent is present per 100 parts of the polyorganosiloxane polymer or a mixture of polyorganosiloxanes.

8. The aqueous silicone emulsion of any of the preceding claims, wherein the at least one leaving groups of the self-catalyzing crosslinking agent is selected from the group consisting of acetoxy, amide, acetamide, aminoxy and oxime.

9. The aqueous silicone emulsion of any of the preceding claims, wherein the self- catalyzing crosslinking agent is of general formula

R₃SiO(R₂SiO)a(RSiO)_bSiR3

ON(CH₂CH₃)₂ where R is the same or different alkyl group of from 1 to 8 carbon atoms inclusive, a is 0 - 100, and b greater than 2 up to 100.

10. The aqueous silicone emulsion of any of the preceding claims, wherein the emulsion further comprises an in situ resin reinforcer selected from the group consisting of methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl orthosilicate, and normal propylorthosilicate.

1 1 . The aqueous silicone emulsion of any of the preceding claims, wherein the emulsion further comprises a nonionic surfactant, cationic surfactant, anionic surfactant, or amphoteric surfactant.

12. The aqueous silicone emulsion of any of the preceding claims, wherein the emulsion further comprises a filler.

13. The aqueous silicone emulsion of claim 12, wherein the filler is silica.

14. The aqueous silicone emulsion of any of the preceding claims, wherein the emulsion comprises a siloxane phase comprising the crosslinked polyorganosiloxane and the siloxane phase has a first refractive index, and the emulsion comprises an aqueous phase comprising the polyvinyl alcohol polymer and a portion of the water and the aqueous phase has a second refractive index, and the first refractive index is substantially the same as the second refractive index.

15. The aqueous silicone emulsion of any of the preceding claims, wherein the polyorganosiloxane or a mixture of polyorganosiloxanes comprises hydroxy terminated polydiorganosiloxane.

16. A method for making a crosslinked polyorganosiloxane emulsion, the method comprising:

A. combining components:

iii. a polyvinyl alcohol polymer, and

iv. water;

polyorganosiloxane emulsion.

17. The method of claim 16, wherein the crosslinked polyorganosiloxane emulsion has a silicone content of from 1 % to 98% by weight of the emulsion.

18. The method of any one of claims 16 to 17, wherein the crosslinked

polyorganosiloxane emulsion has a silicone content of from 40% to 90% or 50% to 70% by weight of the emulsion.

19. The method of any one of claims 16 to 18, wherein 0.1 to 25 parts by weight of the polyvinyl alcohol polymer is present in the crosslinked polyorganosiloxane emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

20. The method of any one of claims 16 to 19, wherein 0.5 to 5 parts by weight of the polyvinyl alcohol polymer is present in the emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

21 . The method of any one of claims 16 to 20, wherein 10 to 200 parts by weight of water is present in the emulsion per 100 parts of the polyorganosiloxane or a mixture of polyorganosiloxanes.

22. The method of any one of claims 16 to 21 , wherein 0.01 to 50 parts by weight of the self-catalyzing crosslinking agent is present in the emulsion per 100 parts of the

polyorganosiloxane or a mixture of polyorganosiloxanes.

23. The method of any one of claims 16 to 22, wherein the least one catalytic leaving group of the self-catalyzing crosslinking agent is selected from the group consisting of acetoxy, amide, aminoxy, acetamine and oxime.

24. The method of any one of claims 16 to 23, wherein the self-catalyzing crosslinking agent is of general formula

R₃SiO(R₂SiO)a(RSiO)_bSiR3

ON(CH₂CH₃)₂

25. The method of any one of claims 16 to 24, comprising the additional step of adding before or after to mixing an in situ resin reinforcer selected from the group consisting of methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl orthosilicate, and normal propylorthosilicate.

26. The method of any one of claims 16 to 25, comprising the additional step of adding a filler either before or after mixing.

27. The method of any one of claims 16 to 26, wherein the filler is silica.

28. The method of any one of claims 16 to 27, wherein the emulsion comprises a siloxane phase comprising the crosslinked polyorganosiloxane and the siloxane phase has a first refractive index, and the emulsion comprises an aqueous phase comprising the polyvinyl alcohol polymer and a portion of the water and the aqueous phase has a second refractive index, and the first refractive index is substantially the same as the second refractive index.