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
1999-05-07
2001-05-01
Dawson, Robert (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...
C524S267000, C524S588000, C525S106000, C528S014000, C528S025000, C528S033000
Reexamination Certificate
active
06225390
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to oil gel compositions for use in cosmetics and pharmaceutical products, cable packing, etc. More particularly, this invention relates to such compositions containing polystyrene-polydimethylsiloxane or polyethylene-polydimethylsiloxane block copolymers and which utilize siloxane monomers as the oil.
BACKGROUND OF THE INVENTION
Silicone gel compositions have been used in a variety of products, including sunscreen gels, moisturizing creams, antiperspirant creams, liquid foundations, and hair gels. Known silicone gel compositions include compositions comprised of silicone oil and wax, silicone oil and silica, and silicone oil and polyoxyalkylene-containing organopolysiloxanes, such as described in European Published Patent Application No. 0,568,102. That application identifies a number of possibilities for components useful as the silicone oil including low and high viscosity diorganopolysiloxanes, including polydimethylsiloxane, cyclic siloxanes, cyclic siloxane solutions of polydimethylsiloxane gums, etc.
Linear block copolymers of polystyrene and polydimethylsiloxane have been synthesized, both by graft and block copolymerization. In block copolymerization of such linear polymers, polystyrene is produced by anionic polymerization with an organo lithium initiator and the living polymer (PS-Li+) created thereby is reacted with hexamethylcyclotrisiloxane, (Me
2
SiO)
3
, in the presence of a polar promoter wherein a block of polydimethylsiloxane grows on the end of the living vinyl aromatic hydrocarbon polymer block. U.S. Pat. No. 5,618,903 describes a block copolymer which is an anionically polymerized block copolymer which is comprised of at least one block of high density (HDPE) polyethylene and at least one block of a polysiloxane, e.g., polydimethylsiloxane. These polymers are useful for impact modification of engineering thermoplastics, flow promoters, and forming coatings with low energy surfaces but have not been used or suggested for use as components of oil gels.
SUMMARY OF THE INVENTION
This invention is a silicone oil gel composition which is comprised of a silicone block copolymer selected from the group consisting of polyethylene-polydimethylsiloxane block copolymers and polystyrene-polydimethylsiloxane block copolymers wherein the overall number average molecular weight is from 2000 to 251,000, the polystyrene content (PSC) is 40% or less by weight, the polystyrene block number average molecular weight is from 1000 to 30,000, and the polyethylene number average block molecular weight is from 1000 to 20,000, the polydimethylsiloxane number average molecular weight is from 1000 to 250,000, wherein the block copolymer is dissolved in a silicone oil which is a cyclic or linear siloxane monomer. Preferred siloxane monomers for use herein are (Me
2
SiO)
3
, (Me
2
SiO)
4
, and (Me
2
SiO)
5
.
DETAILED DESCRIPTION OF THE INVENTION
The polyethylene-polydimethylsiloxane and polystyrene-polydimethylsiloxane block copolymers of this invention and the method of making them are fully described in U.S. Pat. No. 5,618,903, which is herein incorporated by reference. In block copolymerization of such linear polystyrene-polydimethylsiloxane polymers, polystyrene is produced by anionic polymerization with an organo lithium initiator and the living polymer (PS-Li+) created thereby is reacted with hexamethylcyclotrisiloxane, (Me
2
SiO)
3
, in the presence of a polar promoter wherein a block of polydimethylsiloxane grows on the end of the living vinyl aromatic hydrocarbon polymer block.
In general, when solution anionic techniques are used, polymers of anionically polymerizable monomers are prepared by contacting the monomer to be polymerized simultaneously or sequentially with an anionic polymerization initiator such as Group IA metals, their alkyls, amides, silanolates, naphthalides, biphenyls and anthracenyl derivatives. It is preferable to use an organo alkali metal (such as sodium or potassium) compound in a suitable solvent at a temperature within the range from −150° C. to 300° C. preferably at a temperature within the range from 0° C. to 100° C. Particularly effective anionic polymerization initiators are organo lithium compounds having the general formula:
RLi
n
wherein R is an aliphatic, cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radical having from 1 to 20 carbon atoms; and n is an integer of 1-4.
In general, any of the solvents known in the prior art to be useful in the preparation of such polymers may be used. Suitable solvents, then, include straight- and branched-chain hydrocarbons such as pentane, hexane, heptane, octane and the like, as well as, alkyl-substituted derivatives thereof; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and the like, as well as, alkyl-substituted derivatives thereof; aromatic and alkyl-substituted derivatives thereof; aromatic and alkyl-substituted aromatic hydrocarbons such as benzene, naphthalene, toluene, xylene and the like; hydrogenated aromatic hydrocarbons such as tetralin, decalin and the like; linear and cyclic ethers such as methyl ether, methyl ethyl ether, diethyl ether, tetrahydrofuran and the like.
Ethylene may be polymerized as described above with the addition that it is usually best to include a promoter, such as a diamine, to facilitate the reaction. Examples of these amines which include but are not limited to follow: N,N,N′,N′-tetramethylmethylenediamine (TMMDA), N,N,N′,N′-tetramethylethylenediamine (TMEDA), N,N,N′,N′-tetraethylethylenediamine (TEEDA), N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA), N,N,N′,N′tetramethyl-1,4-butanediamine (TMBDA), dipiperidinomethane (DIPIM), 1,2dipiperidinoethane (DIPIE), 1,8-bis(dimethylamino)naphthalene, N,N,N′,N′tetramethyl-o-phenylenediamine (TMOPDA), 1,2-dipyrolidinoethane (DIPIP), 1,3dipiperidinopropane (DIPIP), 1,2-bis(2.6-dimethylpiperidino)cyclohexane (BDMPC), sparteine, and the like.
The ethylene polymerization reaction can be carried out at 0° C. to 100° C. preferably 25° C. to 60° C. The ethylene pressure can be from 10 psig to 1000 psig, preferably 100 to 500 psig, The polymerization time can run from 10 minutes to 2 hours, preferably 30 minutes to 1 hour.
When the polymerization of the ethylene is complete, living polyethylene blocks are present in the polymerization mixture. These are perfectly linear polyethylene-alkyllithiums. These living polyethylenes can then be reacted with cyclic siloxane monomers (R
1
R
2
SiO)
n
, where n=3-10, R
1
and R
2
=alkyl (C
1
-C
20
), alkenyl (C
2
-C
20
), hydrogen, benzyl or phenyl (including alkyl substituted aromatics and polycyclics) and R
1
and R
2
can be the same or different. Specific siloxane monomers include (Me
2
SiO)
3
, (MeHSiO)
3
, (Me
2
SiO)
4
, (Me
2
SiO)
5
, (MeHSiO)
4
, (MeHSiO)
5
, (Ph
2
SiO)
3
, (Ph
2
SiO)
4
, (Ph
2
SiO)
5
, (PhHSiO)
4
, (PhHSiO)
5
, (PhHSiO)
3
, (vinylmethylSiO)
4
, (vinylmethylSiO)
5
, (vinylHSiO)
3
, (vinylHSiO)
4
, (vinylHSiO)
5
, (vinylmethylSiO)
3
, (PhMeSiO)
3
, (PhMeSi)
4
, (PhMeSiO)
5
. Mixtures of monomers can also be used. When a polydimethylsiloxane block is desired with RLi initiator, the monomer is preferably hexamethylcyclotrisiloxane (D3) or octamethylcyclotetrasiloxane (D4).
This polymerization is carried out in the presence of a polar promoter, including, but not limited to, the promoter present during the ethylene polymerization step. Additional promoter can be added. Such promoters include but are not limited to diethers and/or diamines, such as diethylglyme andor TMEDA, cyclic ethers such as tetrahydrofuran, and any promoter known to be useful in anionic polymerizations. Its purpose is to decrease the reaction time of the D3 polymerization. Preferably, this reaction is carried out at a temperature of from 30° C. to 120° C., the concentration of the cyclic siloxane monomer (described herein in terms of hexamethylcyclotrisiloxane) is from 1 to 80 percent by weight, and the amount of pro
Dawson Robert
Haas Donald F.
Robertson Jeffrey B.
Shell Oil Company
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