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
2003-01-02
2003-12-30
Lu, Caixia (Department: 1713)
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...
C524S588000, C524S861000, C524S493000, C525S478000, C528S012000, C528S031000, C528S032000
Reexamination Certificate
active
06670418
ABSTRACT:
BRIEF SUMMARY OF THE INVENTION
The present invention relates to organopolysiloxane compositions which can be crosslinked by addition of Si-bonded hydrogen onto an aliphatic carbon—carbon multiple bond, their preparation and their use.
BACKGROUND OF THE INVENTION
EP-A-316 696 (Wacker Silicones Co.; published on May 24, 1989) describes organopolysiloxane compositions which can be crosslinked by condensation in which surface-treated aluminum hydroxide is used as an additional component in order to improve the electrical properties of the rubber obtained after crosslinkng. EP-A-586 153 (General Electric Co.; published on Mar. 9, 1994) discloses crosslinkable siloxane compositions which comprise additional fillers, such as calcium silicate, aluminum oxide and ceramic beads, which, in conjunction with alkoxy silanes, improves the mechanical properties, in particular the tear propagation resistance, of silicone rubbers.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to crosslinkable organopolysiloxane compositions which comprise
(1) an organopolysiloxane which contains SiC-bonded radicals with aliphatic carbon—carbon multiple bonds, and
(2) an organopolysiloxane with a Si-bonded hydrogen atom or, instead of (1) and (2)
(3) an organopolysiloxane which contains a SiC-bonded radical with aliphatic carbon—carbon multiple bonds and Si-bonded hydrogen atoms,
(4) a catalyst which promotes the addition of Si-bonded hydrogen onto an aliphatic multiple bond,
(5) a reinforcing filler
(6) a non-reinforcing filler having an average particle diameter of less than 30 &mgr;m and a BET surface area of less than 30 m
2
/g and, optionally, further substances.
If the composition according to the invention is a two-component silicone rubber composition, the two components of the silicone rubber compositions according to the invention can comprise all the constituents in any desired combination, with the proviso that one component does not simultaneously comprise siloxanes with an aliphatic multiple bond, siloxanes with Si-bonded hydrogen and the catalyst.
In the context of the present invention, the term organopolysiloxanes is also to be understood as meaning polymeric, oligomeric and dimeric siloxanes.
The organopolysiloxane compositions according to the invention have a content of organic solvent of not more than 3% by weight, preferably not more than 2% by weight, the compositions being, in particular, free from organic solvent
The siloxanes (1) and (2) or (3) used in the compositions according to the invention are chosen, such that crosslinking is possible. Thus, for example, siloxane (1) contains at least two aliphatically unsaturated radicals and siloxane (2) contains at least three Si-bonded hydrogen atoms, or siloxane (1) contains at least three aliphatically unsaturated radicals and siloxane (2) contains at least two Si-bonded hydrogen atoms, or, instead of siloxane (1) and (2), siloxane (3) which contains aliphatically unsaturated radicals and Si-bonded hydrogen atoms in the above mentioned ratios is used.
Organopolysiloxanes (1) which contain SiC-bonded radicals with aliphatic carbon—carbon multiple bonds are linear or branched organopolysiloxanes comprising units of the formula
R
a
R
b
1
S
i
O
4
-
a
-
b
2
(I)
in which
R is a monovalent SiC-bonded, optionally substituted hydrocarbon radical which has 1 to 18 carbon atoms and is free from aliphatic carbon—carbon multiple bonds,
R
1
is a monovalent SiC-bonded hydrocarbon radical with an aliphatic carbon—carbon multiple bond,
a is 0, 1, 2 or 3 and
b is 0, 1 or 2,
with the proviso that the sum a+b is less than or equal to 3 and at least two radicals R
1
are present per molecule.
Examples of radicals R are alkyl radicals, such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl and tert-pentyl radical, hexyl radicals, such as the n-hexyl radical, heptyl radicals, such as the n-heptyl radical, octyl radicals, such as the n-octyl radical and isooctyl radicals, such as the 2,2,4-trimethylpentyl radical, nonyl radicals, such as the n-nonyl radical, decyl radicals, such as the n-decyl radical, dodecyl radicals, such as the n-dodecyl radical, and octadecyl radicals, such as the n-octadecyl radical, cycloalkyl radicals, such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals, aryl radicals, such as the phenyl, naphthyl, anthryl and phenanthryl radical, alkaryl radicals, such as o-, m- and p-tolyl radicals, xylyl radicals and ethylphenyl radicals, and aralkyl radicals, such as the benzyl radical and the &agr;- and the &bgr;-phenylethyl radical.
Examples of substituted radicals R are halogenoalkyl radicals, such as the 3,3,3-trifluoro-n-propyl radical, the 2,2,2,2′,2′,2′-hexafluoroisopropyl radical and the heptafluoroisopropyl radical, and halogenoaryl radicals, such as the o-, m- and p-chlorophenyl radical.
The radical R is preferably a monovalent SiC-bonded hydrocarbon radical which has 1 to 6 carbon atoms and is free from aliphatic carbon—carbon multiple bonds, the methyl radical being preferred.
Examples of radicals R
1
are alkenyl radicals, such as the vinyl, 5-hexenyl, cyclohexenyl, 1-propenyl, allyl, 3-butenyl and 4-pentenyl radical, and alkynyl radicals, such as the ethynyl, propargyl and 1-propynyl radical.
The radical R
1
is preferably alkenyl radicals, the vinyl radical being more preferred.
The siloxanes (1) used according to the invention are preferably those of the formula
R
1
x
SiR
3-x
O(SiR
2
O)
n
(SiR
1
RO)
m
SiR
3-x
R
1
x
(II)
in which
R and R
1
have the meaning given above,
x is 0, 1, 2 or 3, preferably 1,
m is 0 or a number from 1 to 50 and
n is a number from 50 to 100,000,
with the proviso that the siloxanes of formula (II) contain at least two radicals R
1
per molecule and the n units (SiR
2
O) and the m units (SiR
1
RO) can be distributed in the molecule as desired, for example as a block or randomly.
The organopolysiloxanes (1) preferably have an average viscosity of 100 to 200,000 mm
2
/s, more preferably 200 to 100,000 mm
2
/s, at 25° C.
The compositions according to the invention comprise siloxane (1) in amounts of 10% to 80% by weight, preferably 15% to 60% by weight.
Organopolysiloxanes (2) which contain Si-bonded hydrogen atoms and are used are linear, cyclic or branched organopolysiloxanes of units of the formula
R
g
2
H
f
S
i
O
4
-
g
-
f
2
(III)
in which
R
2
has the meaning given above for radical R,
g is 0, 1, 2 or 3 and
f is 0, 1 or 2,
with the proviso that the sum of g+f is less than or equal to 3 and at least 3 Si-bonded hydrogen atoms are present per molecule.
Examples of radical R
2
are the examples mentioned for R, alkyl radicals having 1 to 6 carbon atoms being preferred and the methyl and phenyl radicals being more preferred.
In the siloxanes of units of formula (III), the units containing Si-bonded hydrogen can be arranged in a block or distributed randomly.
The organopolysiloxane (2) used according to the invention contains Si-bonded hydrogen in a range from 0.01% to 1.5% by weight, preferably 0.05% to 1.5% by weight, based on the total weight of the organopolysiloxane (2).
The organopolysiloxanes (2) have an average viscosity of 20 to 50,000 mm
2
/s, preferably 40 to 5000 mm
2
/s, in each case at 25° C.
The siloxanes (2) used according to the invention are preferably essentially linear siloxanes having a chain length of not more than 1000 siloxane units.
The compositions according to the invention comprise siloxane (2) in amounts of 0.2% to 30% by weight, preferably 0.5% to 20% by weight, in particular 1% to 10% by weight.
The siloxanes (1) and (2) used according to the invention are commercially available products or can be prepared by processes customary in chemistry.
Instead of organopolysiloxanes (1) and (2), the compositions according to the invention can comprise organopolysiloxanes (3) which contain both aliphatic carbon—carbon multiple bonds and Si-bonded hydrogen atoms, al
Eller Adolf
Mueller Johann
Brooks & Kushman P.C.
Lu Caixia
Wacker-Chemie GmbH
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