Organopolysiloxane copolymer and method of preparing

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

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C524S860000, C524S863000, C525S474000, C525S477000, C528S018000, C528S031000, C528S032000, C528S033000, C528S034000

Reexamination Certificate

active

06803409

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an organopolysiloxane copolymer and more particularly to an organopolysiloxane copolymer containing trifunctional units, random difunctional units, and linear difunctional units in particular mole ratios. The present invention also relates to a method of preparing the organopolysiloxane copolymer.
BACKGROUND OF THE INVENTION
Organopolysiloxane copolymers comprising linear difunctional siloxane units and methods for their preparation are known in the art. For example, U.S. Pat. No. 3,629,228 to Hartlein et al. discloses a room temperature vulcanizable alkoxy siloxane block copolymer of a polydiorganosiloxane block and a monoorganosiloxane block being endblocked with monorganodialkoxysiloxy units.
U.S. Pat. No. 5,747,608 to Katsoulis et al. discloses a rubber-modified rigid silicone resin comprising a copolymerized reaction product of (A) an organosilicon composition selected from the group consisting of (I) an organosilicone resin, (II) hydrolyzable precursors of (I), and (III) hydrolyzate formed from (II); and (B) a silicone rubber.
U.S. Pat. No. 5,830,950 to Katsoulis et al. discloses a method of producing a rubber-modified rigid silicone resin comprising the steps of (1) dissolving in an organic solvent, the following components so as to form a solution therefrom, said components comprising: (A) an organosilicon composition selected from the group consisting of (I) an organosilicone resin, (II) hydrolyzable precursors of (I), and (III) a hydrolyzate formed from (II); (B) a silicone rubber; and (C) a condensation catalyst; (2) copolymerizing component (B) with component (A) without causing precipitation of the copolymerized product from solution or the gelation thereof; (3) devolatilizing the solution containing the copolymerized product produced from components (A) and (B); and (4) heating said devolatilized, copolymerized product to as temperature sufficient to cause the same to cure.
U.S. Pat. No. 6,046,283 to Katsoulis et al. teaches a rubber-modified rigid silicone resin comprising a copolymerized reaction product of (A) an organosilicon composition selected from the group consisting of (I) an organosilicone resin, (II) hydrolyzable precursors of (I), and (III) a hydrolyzate formed from (II); (B1) a first silicone rubber having a nonfunctional linear chain length between functional groups from 6 to 100; and (B2) a second silicone rubber having terminal functional groups and a degree of polymerization from about 200 to 1,000.
U.S. Pat. No. 4,395,443 to Shimizu et al. discloses a silicone film-forming composition comprising a condensation product of a benzene soluble polysiloxane and a silanol terminated polydiorganosiloxane in combination with a mixed solvent comprising a volatile organosilicon compound and a hydrocarbon solvent.
U.S. Pat. No. 3,974,122 to Sato et al. discloses a silicone resin molding composition comprising (a) a vinyl-containing organopolysiloxane composed of randomly copolymerized tri-, di-, and mono-functional siloxane units in specific mole fractions, (b) a vinyl-containing organopolysiloxane with at least one block composed of from 5 to 1,000 diorganosiloxane units bonded linearly to each other in an uninterrupted sequence, (c) an organohydrogenpolysiloxane, and (d) a platinum catalyst.
Although the aforementioned references describe various organopolysiloxane copolymers and methods of preparing the copolymers, they do not teach the organopolysiloxane copolymer or method of the present invention.
SUMMARY OF THE INVENTION
The present invention is directed to an organopolysiloxane copolymer, comprising (i) R
1
SiO
3/2
units, (ii) random R
2
2
SiO
2/2
units, and (iii) linear (R
3
2
SiO)
n
units, wherein R
1
is hydrocarbyl or halogen-substituted hydrocarbyl, R
2
and R
3
are independently R
1
or H, n has an average value of from 5 to 500, the mole ratio of R
1
SiO
3/2
units to R
2
2
SiO
2/2
units is from 1 to 30, and the mole ratio of R
1
SiO
3/2
units and R
2
2
SiO
2/2
units combined to (R
3
2
SiO)
n
units is from 3 to 600 when the copolymer contains aliphatic unsaturation or from 1 to 600 when the copolymer is free of aliphatic unsaturation.
The present invention is also directed to a method of preparing an organopolysiloxane copolymer, comprising the steps of:
(I) combining (a) an organosilane having the formula R
1
SiX
1
3
and (b) an organosilane having the formula R
2
2
SiX
2
2
with (c) water in the presence of (d) a polydiorganosiloxane having the formula X
3
(R
3
2
SiO)
p
SiR
3
2
X
3
and (e) an organic solvent to form a first reaction mixture comprising an organic phase and an aqueous phase, wherein R
1
is hydrocarbyl or halogen-substituted hydrocarbyl; R
2
and R
3
are independently R
1
or H; X
1
, X
2
, and X
3
are independently a hydrolysable group or —OH; p has an average value of from 4 to 499; the mole ratio of (a) to (b) is from 1 to 30; and the mole ratio of (a) and (b) combined to (d) is from 1 to 600; provided when X
1
, X
2
, and X
3
are independently a hydrolysable group that does not react with water to form an acid, or —OH, the reaction mixture contains (f) an acid catalyst;
(II) separating the organic phase from the aqueous phase;
(III) washing the organic phase with water;
(IV) adding (g) a condensation catalyst to the washed organic phase to form a second reaction mixture; and
(V) distilling the second reaction mixture to remove water.
The present invention is further directed to a method of preparing an organopolysiloxane copolymer, comprising combining (a′) an organosilane having the formula R
1
SiX
1
3
and (b′) an organosilane having the formula R
2
2
SiX
2
2
with (c) water in the presence of (d′) a polydiorganosiloxane having the formula X
3
(R
3
2
SiO)
p
SiR
3
2
X
3
, (e) an organic solvent, and (f) an alkali catalyst, to form a reaction mixture comprising an organic phase and an aqueous phase, wherein R
1
is hydrocarbyl or halogen-substituted hydrocarbyl; R
2
and R
3
are independently R
1
or H; X
1
, X
2
, and X
3
are independently a hydrolysable group that does not react with water to form an acid, or —OH; p has an average value of from 4 to 499; the mole ratio of (a′) to (b′) is from 1 to 30; and the mole ratio of (a′) and (b′) combined to (d′) is from 1 to 600; for a time and at a temperature sufficient to form the copolymer.
The organopolysiloxane copolymer of the present invention exhibits superior cohesive strength, adhesive strength, and thermal conductivity.
The method of the present invention produces organopolysiloxane copolymers in high yield from readily available starting materials. Moreover, the method can be conveniently controlled to produce organopolysiloxane copolymers having a wide range of thermal and mechanical properties.
The organopolysiloxane copolymer of the present invention can be used as a silicone adhesive to bond various inorganic and organic substrates. The organopolysiloxane copolymer can also be used as a toughening agent or an adhesion promoter in rigid materials such as silicone resins, epoxy resins, phenolic resins, polyamide resins, and cyanate ester resins. Furthermore, the organopolysiloxane copolymers can be used as an additive in thermoplastic organic polymers to improve the fire-resistance of the polymer.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.
DETAILED DESCRIPTION OF THE INVENTION
An organopolysiloxane according to the present invention comprises (i) R
1
SiO
3/2
units, (ii) random R
2
2
SiO
2/2
units, and (iii) linear (R
3
2
SiO)
n
units, wherein R
1
is hydrocarbyl or halogen-substituted hydrocarbyl, R
2
and R
3
are independently R
1
or H, n has an average value of from 5 to 500, the mole ratio of R
1
SiO
3/2
units to R
2
2
SiO
2/2
units is from 1 to 30, and the mole ratio of R
1
SiO
3/2
units and R
2
2
SiO
2/2
units combined to (R
3
2
SiO)
n
units is from 3 to 600 when the copolymer contains aliphatic unsaturatio

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