Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-11-10
2001-11-06
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S015000, C528S032000, C528S037000, C528S031000, C528S483000, C522S099000, C522S170000
Reexamination Certificate
active
06313255
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to telechelic silicone polymers. In particular, this invention relates to telechelic organopolysiloxanes having multiple cationic polymerizable end groups such as epoxy, vinyl ether, or propenyl ether end groups, and to methods for synthesis of the same.
Telechelic polymers are terminally-functionalized, macromolecular polymers. Silicone polymers (organopolysiloxanes) having epoxy and/or vinyl ether functional groups are of particular utility in curable compositions to produce release coatings, that is, coatings which release materials that would ordinarily be adherent. Such materials include pressure-sensitive adhesives for labels, decorative laminates, transfer tapes, and the like.
One common approach to manufacture of organopolysiloxane release coatings is based on hydrosilation of vinyl-terminated polysiloxanes with hydride crosslinkers. Another approach is based on photocatalyzed cross-linking of epoxy-functional organopolysiloxanes. U.S. Pat. Nos. 4,208,503, 4,421,904, 4,640,967, 5,187,251, and 5,217,805, for example, describe epoxy-functional polysiloxanes useful for the preparation of release coatings. These polysiloxanes contain the epoxy functionality located on the polymer ends and/or randomly distributed on the siloxane backbone. These polymers are then mixed with a photo-catalyst such as diaryliodonium hexafluoroantimonate, and cured by an irradiation with UV light to provide a release coating.
The major disadvantage of epoxy-based release coatings over those made by the hydrosilation of vinyl-terminated polysiloxanes is their brittleness. The brittleness of epoxy-functional systems is related to the presence of relatively short segments of dimethylsiloxane units (usually from 5 to 20 dimethylsiloxane units) between crosslinked islands of organic polyethers which have high glass transition temperature. In an attempt to solve this problem, epoxy end-stopped siloxane polymers have been manufactured having 100 or more dimethylsiloxane units between the epoxy functionalized groups. Cure of such polymers results in flexible coatings, but such systems suffer from a very low activity (very slow cure). Slow cure severely limits practical use of such long-chain siloxane polymers.
Accordingly, there remains a continuing need in the art for new functionalized siloxane polymers with both improved cure activity and improved release coating properties upon cure.
SUMMARY OF THE INVENTION
The above-described and other drawbacks and deficiencies of the prior art are overcome or alleviated by the telechelic polymers described herein, comprising polysiloxane polymers having multiple functional end-groups of formula (I)
G—R
3
—SiR
1
R
2
O(SiR
1
R
2
O)
m
SiR
1
R
2
—R
3
—G (I)
wherein R
1
and R
2
are each independently monovalent alkyl, alkoxy, aryl, aryloxy, and halohydrocarbon radicals having from 1 to 20 carbon atoms; m is an integer in the range from 10 to about 1000; R
3
is a divalent hydrocarbon radical having from 2 to 18 carbon atoms; and G is a silicon-based functionalized end group selected from the group consisting of epoxides, vinyl ethers, propenyl ether, or a combination thereof. Preferably, G has the structure (II) or (III)
wherein B is a divalent silicon radical of the formula —SiR
7
E—, p is an integer in the range from 1 to 5, R
4
, R
5
, R
6
, and R
7
are each independently monovalent alkyl, alkoxy, aryl, aryloxy, or halohydrocarbon radicals, having up to about 20 carbons, q is 0 or 1, and E is a monovalent radical having an epoxy, vinyl ether, or propenyl ether functionality. Such polymers are produced by the reaction of a polyorganosiloxane having at least one vinyl end group with an excess of an oligomeric organosiloxane having at least three Si—H functional groups, to yield a telechelic siloxane polymer having multiple Si—H functionalities; then reacting this polymer with an excess of an alkenyl epoxide or vinyl ether to yield a telechelic polyorganosiloxane with multiple epoxy and/or vinyl ether end-groups.
DETAILED DESCRIPTION OF THE INVENTION
The composition of the present invention comprises organopolysiloxane polymers having multiple epoxy or vinyl ether end groups, wherein the polymers have formula (I) below
G—R
3
—SiR
1
R
2
O(SiR
1
R
2
O)
m
SiR
1
R
2
—R
3
—G (I)
wherein R
1
and R
2
are each independently monovalent alkyl, alkoxy, aryl, aryloxy, and halohydrocarbon radicals having from 1 to 20 carbon atoms. Preferred monovalent halohydrocarbon radicals have the formula C
n
F
2n+1
CH
2
CH
2
—, wherein n is an integer in the range from 1 to about 18, preferably in the range from 1 to 8. Preferably, R
1
and R
2
are monovalent hydrocarbon radicals having up to 20 carbon atoms or more preferably up to six carbon atoms. Most preferably, R
1
and R
2
are methyl or phenyl radicals.
In formula (I), m is an integer in the range from 10 to about 1000, preferably in the range from about 50 to about 200.
G in formula (I) is a silicon-based functionalized end group selected from the group consisting of epoxides, vinyl ethers, propenyl ether, or a combination thereof. Preferably, G has structure (II) or (III)
wherein B is a divalent silicon radical of the formula —SiR
7
E—, p is an integer in the range from 1 to 5, R
4
, R
5
, R
6
, and R
7
are independently monovalent alkyl, alkoxy, aryl, aryloxy, and halohydrocarbon radicals having from 1 to 20 carbon atoms, preferably from 1 to 8 carbon atoms. Preferred monovalent halohydrocarbon radicals have the formula C
n
F
2n+1
CH
2
CH
2
—, wherein n is an integer in the range from 1 to about 18, preferably in the range from 1 to 8. q is 0 or 1 and E is independently a monovalent radical having an epoxy, vinyl ether, or propenyl ether functionality.
Suitable monovalent radicals having an epoxy functional group 20 comprise from 2 to about 26, preferably from 2 to about 18, carbon atoms, this epoxy functional group either being present at the end of the radical chain, of the type (IV):
or in an intermediate position, of the type (V):
It is possible for this intermediate position epoxy-functional group to be present on a cyclic part of the radical, in particular a ring having from 5 to 7 members, preferably a 6-membered ring of the type (VI):
Examples of suitable radicals having epoxy functionality are structures represented by (VII), (VIII), (IX) and (X):
Suitable radicals having vinyl ether or propenyl ether functionalities are known in the art, being represented by the general formula (XI)
—CH
2
CH
2
(CH
2
)
s
—L
t
—(CH
2
)
s
—OCH═CHR
8
(XI)
wherein each s is independently an integer in the range from 0 to 12; t is an integer in the range from 0 to 12; R
8
is a hydrogen or methyl radical; and L is a straight-chain or branched divalent hydrocarbon group having up to about 8 carbon atoms, a straight chain or branched unsaturated divalent hydrocarbon group having up to about 8 carbon atoms, divalent aromatic hydrocarbon having up to about 10 carbon atoms, or a straight-chain or branched divalent oxyalkylene group having up to about 8 carbon atoms. Preferably, L is a divalent methylene (—CH
2
—), ethylene (—C
2
H
4
—), 1,2-propylene (—CH
2
CH(CH
3
)—), or oxyethylene (—OCH
2
CH
2
—)group.
The end-group functionalized polysiloxanes (I) are produced by the reaction of a diorganosiloxane polymer having vinyl end groups (XII)
CH
2
═CH—(CH
2
)
v
SiR
1
R
2
O(SiR
1
R
2
O)
m
SiR
1
R
2
(CH
2
)
v
—CH═CH
2
(XII)
wherein R
1
, R
2
, and m are as defined above, and v is an integer from 0 to 16, with an excess of an oligomeric organosiloxane having at least three Si—H functional groups, in the presence of an effective amount of a precious metal catalyst. Reaction of polymers (XII) with oligomeric organosiloxanes is described, for example in U.S. Pat. No. 5,258,480 and U.S. Pat. No. 5,391,676, both of which are incorporated by reference herein. Suitable diorganosiloxane polymers having vinyl end groups (XII) are known in the art, and have from 10 to about 1000 siloxane moieties. Preferred diorganosiloxane polym
General Electric Company
Moore Margaret G.
Peng Kuo-Liang
LandOfFree
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