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
2000-02-21
2001-10-16
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...
C524S261000, C524S265000, C524S267000, C524S268000, C524S462000, C524S545000, C524S588000, C525S474000, C528S025000, C528S026000, C528S029000, C528S031000, C528S042000
Reexamination Certificate
active
06303675
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to a silicone rubber composition, and more particularly relates to a silicone rubber composition that can be made into a silicone rubber with superior water and oil repellency after curing. Silicone rubbers whose main component is a dimethylpolysiloxane have excellent weather resistance, heat resistance, cold resistance, and so on, and are used in applications that demand these characteristics. A drawback to this type of silicone rubber, however, is that when it is used repeatedly for an extended period, it loses its rubber elasticity, lubricity decreases, and it wears away. This material is therefore not always satisfactory in applications that demand such characteristics, such as the rubber inserts of automobile wiper blades, rubber members used for printing type, and keyboard pad rubber members. Consequently, there have been attempts at enhancing the stress durability, lubricity, and so on of silicone rubber by introducing fluorine atom-containing organic groups into the organopolysiloxanes that make up these silicone rubbers. For instance, Japanese Laid-Open Patent Application H9-226529 proposes an automobile wiper blade composed of a silicone rubber whose main component is an organopolysiloxane containing &ggr;-trifluoropropyl groups. There have also been attempts at enhancing the stress durability, lubricity, and so on of silicone rubber by adding a fluoro-resin powder to the silicone rubber. For instance, Japanese Laid-Open Patent Application H5-117530 proposes an automobile wiper blade composed of a silicone rubber in which a fluoro-resin powder is added to a silicone rubber. Japanese Laid-Open Patent Application S60-36171 proposes a silicone rubber that comprises a fluoro-resin powder added to a silicone rubber, and that is suited for printing type rubber members. All of these silicone rubbers, however, were inadequate in terms of their water and oil repellency, and were therefore not completely satisfactory in certain applications.
The inventors arrived at the present invention as a result of diligent study into the above problems. Specifically, it is an object of the present invention to provide a silicone rubber composition that can be made into a silicone rubber with superior water and oil repellency after curing.
SUMMARY OF INVENTION
The present invention is a silicone rubber composition characterized by containing the following perfluoroalkyl group-containing polydiorganosiloxane in an amount of 0.01 to 50 wt %: a perfluoroalkyl group-containing polydiorganosiloxane having on a side chain (F1) an organic group selected from the group consisting of polyoxyalkylene group-containing organic groups, C
12
or higher alkyl groups, and polydialkylsiloxane chain-containing organic groups, and having on a side chain or at a molecular chain terminal (F2) a perfluoroalkyl group-containing organic group described by the general formula
F(CF
2
)
a
—R
1
—
where R
1
is selected from the group consisting of an alkylene group, an alkyleneoxyalkylene group, and a group in which ═CO or —COO— is present in an alkylene chain, and a is an integer of at least 3, and having a weight average molecular weight of at least 1000.
DESCRIPTION OF INVENTION
The present invention is a silicone rubber composition characterized by containing the following perfluoroalkyl group-containing polydiorganosiloxane in an amount of 0.01 to 50 wt %: a perfluoroalkyl group-containing polydiorganosiloxane having on a side chain (F1) an organic group selected from the group consisting of polyoxyalkylene group-containing organic groups, C
12
or higher alkyl groups, and polydialkylsiloxane chain-containing organic groups, and having on a side chain or at a molecular chain terminal (F2) a perfluoroalkyl group-containing organic group described by the general formula
F(CF
2
)
a
—R
1
—
where R
1
is selected from the group consisting of an alkylene group, an alkyleneoxyalkylene group, and a group in which ═CO or —COO— is present in an alkylene chain, and a is an integer of at least 3, and having a weight average molecular weight of at least 1000.
Here, the polyoxyalkylene group-containing organic groups of (F1) are described by the general formula:
—(R
2
)
b
—O—(R
3
O)
c
—R
4
where R
2
is a divalent hydrocarbon group, R
3
is a divalent hydrocarbon group having 1 to 4 carbon atoms, R
4
is selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group, and an acyl group, b is 0 or 1, and c is an integer from 1 to 300, and preferably an integer of at least 5. Examples of C
12
or higher alkyl groups include n-dodecyl groups, n-tetradecyl groups, n-hexadecyl groups, and n-octadecyl groups. Examples of polydialkylsiloxane chain-containing organic groups include alkyleneoxyalkylene groups or alkylene groups bonded to a polydimethylsiloxane chain. It is preferable here for the degree of polymerization of the polydialkylsiloxane to be at least 5. Examples of such polydialkylsiloxanes include compounds described by the following general formula.
In the formula 1, R is a substituted or unsubstituted monovalent hydrocarbon group, specific examples of which include C
1
to C
30
alkyl groups, alkenyl groups, aryl groups, and arylalkyl groups. Of these, methyl and phenyl groups are typical. R
F
is a perfluoroalkyl group-containing organic group described by the above-mentioned general formula:
F(CF
2
)
a
—R
1
—
where R
1
is selected from a group consisting of an alkylene group, an alkyleneoxyalkylene group, and a group in which ═CO or —COO— is present in an alkylene chain, and a is an integer of at least 3. Ethylene and propylene groups are preferred as the alkylene group of R
1
, and examples of the alkyleneoxyalkylene group of R
1
include the ethyleneoxyethylene group, ethyleneoxypropylene group, and propyleneoxypropylene group. In formula 1, D is an organic group selected from the group consisting of polyoxyalkylene group-containing organic groups, C
12
or higher alkyl groups, and polydialkylsiloxane chain-containing organic groups. In formula 1, E is a group selected from among R, R
F
, and D, x is a number from 0 to 500, y is a number from 1 to 500, and z is a number from 1 to 500. It is preferred for (x+y+z) to be between 2 and 1500. When at least one of the molecular chain terminals E (F2) of this polydiorganosiloxane is a perfluoro group-containing organic group, y may be 0. It is preferable that the perfluoro group-containing organic group of (F2) and the non-fluorine-based substituents of (F1) are arranged as a graft chain with respect to the siloxane main chain.
The compounds described by the following chemical structural formulas are examples of such a perfluoroalkyl group-containing polydiorganosiloxane.
This perfluoroalkyl group-containing polydiorganosiloxane can be manufactured, for example, by heating an alkenyl group-containing polyoxyalkylene compound described by formula:
CH
2
═CHCH
2
(OC
2
H
4
)
10
H,
such as an &agr;-olefin or other such alkenyl group-containing hydrocarbon compound, or a vinyl group-containing dimethylpolysiloxane such as:
CH
2
═CH {(CH
3
)
2
SiO}
40
(CH
3
)
2
SiR
2
,
where R
2
is a monovalent hydrocarbon group, in the presence of chloroplatinic acid or another such catalyst for a hydrosilylation reaction and, if necessary, in the presence of an organic solvent so that this compound is subjected to an addition reaction to a polysiloxane described by the following formula:
The proportion of the silicone rubber composition accounted for by this perfluoroalkyl group-containing polydiorganosiloxane is between 0.01 and 50 wt %, and preferably between 0.1 and 30 wt %, and even more preferably between 0.2 and 20 wt %.
The silicone rubber composition of the present invention contains the above-mentioned perfluoroalkyl group-containing polydiorganosiloxane in an amount of 0.01 to 50 wt %, and becomes a silicone rubber upon curing. The silicone rubber composition of the present invention is obtained by adding the above-mentioned perfluoroalkyl group-containing pol
Honma Hiroshi
Kobayashi Hideki
Masatomi Toru
Boley William F.
Cesare James L. De
Dawson Robert
Dow Corning Toray Silicone Company, Ltd.
Robertson Jeffrey B.
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