Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-01-24
2001-05-29
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S837000, C008S115510, C008SDIG001, C424S401000, C424S070120, C528S034000
Reexamination Certificate
active
06239211
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
FIELD OF THE INVENTION
This invention is directed to emulsions containing silicone particles in which the emulsion is prepared by first emulsifying organosilicon oligomers, and then polymerizing the emulsified larger particles of oligomers to a siloxane polymer of higher viscosity and/or higher molecular weight using a condensation specific acid catalyst.
BACKGROUND OF THE INVENTION
While U.S. Pat. No. 2,891,920 (Jun. 23, 1959) and U.S. Pat. No. 3,294,725 (Dec. 27, 1966) each teach the use of condensation specific acid catalysts for polymerizing oligomers to siloxane polymers of higher viscosity and/or higher molecular weight, neither patent suggests that siloxane polymers exhibiting improved release properties can be obtained by including in the process an alkyltrialkoxysilane R′Si(OR″)
3
where R′ and R″ represent alkyl groups, and R′ contains at least eight, preferably at least twelve, and most preferably at least sixteen or more carbon atoms.
BRIEF SUMMARY OF THE INVENTION
This invention relates to a method of preparing an emulsion containing particles of an organopolysiloxane. The emulsion is prepared by (i) combining a silanol endblocked siloxane oligomer, an alkyltrialkoxysilane oligomer, water, and a nonionic surfactant or an anionic surfactant; (ii) emulsifying the oligomers to form particles in the emulsion, by agitating the ingredients or by using a high shear device; (iii) adding a condensation specific acid catalyst to the emulsion of oligomers; (iv) polymerizing the oligomers to form an organopolysiloxane polymer; and (v) continuing polymerizing step (iv) until the resulting organosiloxane polymer has the desired viscosity, which is preferably a viscosity in the range of about 20,000 to about ten million centipoise (mPa·s).
Emulsions prepared according to this invention are capable of functioning as a means of delivering polymers of high molecular weight and tailored Theological properties to the human body, i.e., as in a shampoo base to provide styling and conditioning benefits to human hair, or as a delivery mechanism for use in skin care applications. They can also be used in paper coating, textile coating, and home care applications, for delivering high molecular weight polymers to various types of surfaces and substrates.
These and other features of the invention will become apparent from a consideration of the detailed description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not applicable.
DETAILED DESCRIPTION OF THE INVENTION
The silanol endblocked siloxane oligomer used herein has a structure which can be represented generally by the formula shown below:
In the formula, the R1 to R6 groups generally comprise an alkyl group containing 1-6 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; an aryl group such as phenyl; or alkyl and aryl groups. The value of n can vary from 2-300, thus providing oligomers having a viscosity at 25° C. ranging from about 20 to about 100,000 centipoise (mPa·s).
Most preferred are silanol endblocked dimethylsiloxane oligomers of the structure shown below:
The silanol endblocked dimethylsiloxane oligomer may also contain small amounts of RSiO
3/2
trifunctional “T” units at random locations in the oligomer chain. This provides a point of branching, and three or more silanol end groups which provide subsequent growth at three or more reaction sites in the same molecule, during the silanol-silanol condensation polymerization.
An alkyltrialkoxysilane R′Si(OR″)
3
wherein R′ and R″ each represent an alkyl group is included during the polymerization process. Alkyltrialkoxysilanes undergo hydrolysis with water to form R′Si(OH)
3
which participates in the condensation polymerization, or the alkyltrialkoxysilane can react directly with silanols of the siloxane oligomer forming an ≡SiO bond and liberating an alcohol molecule.
Some examples of alkyltrialkoxysilanes are (C1) methyltrimethoxysilane, (C2) ethyltrimethoxysilane, (C3) propyltrimethoxysilane, (C4) n-butyltrimethoxysilane, (C6) hexyltrimethoxysilane, phenyltrimethoxysilane, (C8) octyltrimethoxysilane, octyltriethoxysilane, (C12) dodecyltrimethoxysilane, dodecyltriethoxysilane, (C16) hexadecyltriethoxysilane, hexadecyltrimethoxysilane, (C18) octadecyltriethoxysilane, octadecyltrimethoxysilane, (C20) eicosyltrimethoxysilane, and (C30) triacontyltrimethoxysilane.
However, as noted above, siloxane polymers exhibiting improved release properties can be obtained by including in the process the alkyltrialkoxysilanes wherein R′ contains at least eight, preferably at least twelve, and most preferably at least sixteen or more carbon atoms.
According to the method of the present invention, the organosilicon oligomers are first mechanically emulsified in water using an anionic or a nonionic surfactant, and then the catalyst is added to polymerize the emulsified larger particle size oligomers to the desired polymer viscosity.
Useful anionic surfactants include alkali metal sulfosuccinates; sulfonated glyceryl esters of fatty acids such as sulfonated monoglycerides of coconut oil acids; salts of sulfonated monovalent alcohol esters such as sodium oleyl isothionate; amides of amino sulfonic acids such as the sodium salt of oleyl methyl tauride; sulfonated products of fatty acid nitrites such as palmitonitrile sulfonate; sulfonated aromatic hydrocarbons such as sodium alpha-naphthalene monosulfonate; condensation products of naphthalene sulfonic acids with formaldehyde; sodium octahydro anthracene sulfonate; alkali metal alkyl sulfates; ether sulfates having alkyl groups of eight or more carbon atoms; and alkylaryl sulfonates having one or more alkyl groups of eight or more carbon atoms.
Anionic surfactants including olefin sulfonates can also be employed, representative of which are sodium alpha olefin sulfonates sold under the tradename BIO-TERGE AS-40 by the Stephan Company, Northfield, Ill. These sodium C
14-16
olefin sulfonates are mixtures of long chain sulfonate salts prepared by sulfonation of C
14-16
alpha olefins. They consist chiefly of sodium alkene sulfonates and sodium hydroxyalkane sulfonates.
Useful nonionic surfactants preferably have a hydrophiliclipophilic balance (HLB) of 10-20. Nonionic surfactants with HLB of less than 10 may be used, but the emulsion stability may be very poor due to limited solubility of the nonionic surfactant in water. When using a nonionic surfactant with HLB less than 10, a nonionic surfactant with HLB greater than 10 should be added during or after polymerization.
Commercial types of nonionic surfactants can be exemplified by 2,6,8-trimethyl-4-nonyloxy polyethylene oxyethanols (6EO) and (10EO) sold under the trademarks TERGITOL® TMN-6 and TERGITOL® TMN-10; alkyleneoxy polyethylene oxyethanol (C
11-15
secondary alcohol ethoxylates 7EO, 9EO, and 15EO) sold under the trademarks TERGITOL® 15-S-7, TERGITOL® 15-S-9, TERGITOL® 15-S-15; other C
11-15
secondary alcohol ethoxylates sold under the trademarks TERGITOL® 15-S-12, 15-S-20, 15-S-30, 15-S-40; and octylphenoxy polyethoxy ethanol (40EO) sold under the trademark TRITON® X-405. All of these surfactants are sold by Union Carbide Corporation, Danbury, Conn.
Other types of commercial nonionic surfactants are nonylphenoxy polyethoxy ethanol (10EO) sold under the tradename MAKON 10 by Stepan Company, Northfield, Ill.; polyoxyethylene 23 lauryl ether (Laureth-23) sold commercially under the tradename BRIJ 35L by ICI Surfactants, Wilmington, Del.; and RENEX 30, a polyoxyethylene ether alcohol with an HLB of about 14.5 sold by ICI Surfactants, Wilmington, Del.
The reaction to polymerize the emulsified organosilicon oligomers is carried out in a simple reactor containing water, at least one anionic (ionic) surfactant or nonionic surfactant, and a catalyst.
The condensation specific acid catalyst can be a strong acid such
Halloran Daniel Joseph
Keeping Stuart
Zimmerman Brett Lee
Cesare James L. De
Dow Corning Corporation
Moore Margaret G.
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