Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2002-03-14
2004-03-02
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...
C528S031000, C528S032000
Reexamination Certificate
active
06699956
ABSTRACT:
This invention relates to highly dielectric addition type curable compositions which are less hygroscopic and able to form films and cure into products having improved dielectric properties including a large dielectric constant and a low dielectric loss and finding practical use in a variety of applications.
BACKGROUND OF THE INVENTION
Engineers have made efforts to ameliorate the performance of electric and electronic parts such as electroluminescent devices and film capacitors while reducing the size and weight thereof. As the dielectric material used therein, organic polymers having a large dielectric constant are of interest and have been used. It is believed that this trend becomes increasingly prevalent in the future.
The dielectric organic polymers which are known in the art include cyanoethyl polysaccharides such as cyanoethyl cellulose, cyanoethyl starch and cyanoethyl pullulan, cyanoethyl polysaccharide derivatives such as cyanoethyl hydroxyethyl cellulose and cyanoethyl glycerol pullulan, cyanoethyl polyols such as cyanoethyl polyvinyl alcohol, and fluoro-resins such as polyvinylidene fluoride.
However, these substances have many drawbacks and do not perform satisfactorily when applied in electric and electronic fields. More particularly, cyanoethyl products of polysaccharides and polysaccharide derivatives and cyanoethyl polyvinyl alcohol have the common drawback that they are highly hygroscopic and readily alter electrical properties by moisture absorption, sometimes detracting from the reliability of electric and electronic parts. This phenomenon can be prohibited by taking such measures as careful control of humidity during the manufacturing process and removal of absorbed water. These measures, however, are regarded negative from the productivity standpoint and hardly expected to exert satisfactory effects.
Also undesirably, cyanoethyl cellulose and cyanoethyl starch are difficult to form film. Cyanoethyl hydroxyethyl cellulose, cyanoethyl glycerol pullulan, and cyanoethyl polyvinyl alcohol undergo large changes of dielectric constant with temperature.
The fluoro-resins such as polyvinylidene fluoride have the advantages of a low moisture absorption and reduced changes of dielectric constant with temperature, but their dielectric constant is approximately half of that of cyanoethyl polysaccharides and polysaccharide derivatives.
U.S. Pat. No. 4,843,517 discloses a highly dielectric organic material base on a cyanoalkyl group-bearing organopoly-siloxane. This is semi-solid or solid and difficult to handle in forming a film. Such difficulty can be avoided by dissolving the material in polar solvents such as acetone and dimethylformamide. However, the solutions are not applicable to various organic resin substrates because the substrates can be attacked by the solvents. The applicable substrates are thus restricted.
SUMMARY OF THE INVENTION
An object of the invention is to provide a highly dielectric addition type curable composition which can be prepared as a relatively low viscosity liquid without a need for solvents, which is easy to handle, less hygroscopic, and able to form a film, and which cures into a product having improved dielectric properties including a large dielectric constant and a low dielectric loss.
We have found that an addition type curable composition comprising (A) an organopolysiloxane containing a cyanoalkyl group and a monovalent hydrocarbon group having an aliphatic unsaturated bond, (B) an organohydrogenpolysiloxane containing a cyanoalkyl group, and (C) a platinum group metal catalyst is liquid without a need for solvents, that is, can be prepared to a relatively low viscosity and is thus improved in handling. The composition is less hygroscopic and able to form a film, and cures into a product having improved dielectric properties including a large dielectric constant and a low dielectric loss.
The present invention provides a highly dielectric addition type curable composition comprising (A) an organopolysiloxane containing a cyanoalkyl group and a monovalent hydrocarbon group having an aliphatic unsaturated bond, (B) an organohydrogenpolysiloxane containing a cyanoalkyl group, and (C) a platinum group metal catalyst.
A preferred embodiment of the invention is a highly dielectric addition type curable composition comprising
(A) an organopolysiloxane containing a cyanoalkyl group and a monovalent hydrocarbon group having an aliphatic unsaturated bond, represented by the average compositional formula (I):
R
1
a
R
2
b
R
3
c
SiO
(4+a+b+c)/2
(I)
wherein R
1
is a cyanoalkyl group having 3 to 5 carbon atoms, R
2
is a monovalent hydrocarbon group of 2 to 6 carbon atoms having an aliphatic unsaturated bond, R
3
is a monovalent hydrocarbon group having 1 to 10 carbon atoms other than R
1
and R
2
, letter “a” is a number of 0.2 to 0.95, “b” is a number of 0.05 to 0.7, “c” is a number of 0.05 to 1.0, and a+b+c is 1.05 to 1.9,
(B) an organohydrogenpolysiloxane containing a cyanoalkyl group, represented by the average compositional formula (II):
R
4
k
R
5
m
R
6
n
SiO
(4+k+m+n)/2
(II)
wherein R
4
is a cyanoalkyl group having 3 to 5 carbon atoms, R
5
is hydrogen, R
6
is a monovalent hydrocarbon group having 1 to 10 carbon atoms other than R
4
, letter “k” is a number of 0.2 to 0.7, “m” is a number of 0.2 to 0.7, “n” is a number of 1.0 to 1.6, and k+m+n is 2.0 to 2.3, and
(C) a platinum group metal catalyst.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For the highly dielectric addition type curable compositions of the invention, the presence of nitrile groups is essential. The organopolysiloxane (A) and the organohydrogenpolysiloxane (B) used herein must contain cyanoalkyl groups in their structural units. This is because highly polar nitrile groups are oriented and polarized in an electric field whereby dielectric constant is increased.
Component (A) is an organopolysiloxane containing a cyanoalkyl group and a monovalent hydrocarbon group having an aliphatic unsaturated bond, which is preferably represented by the average compositional formula (I) below.
R
1
n
R
2
b
R
3
c
SiO
(4+a+b+c)/2
(I)
Herein R
1
is a cyanoalkyl group having 3 to 5 carbon atoms, R
2
is a monovalent hydrocarbon group of 2 to 6 carbon atoms having an aliphatic unsaturated bond, R
3
is a monovalent hydrocarbon group having 1 to 10 carbon atoms other than R
1
and R
2
, letter “a” is a number of 0.2 to 0.95, “b” is a number of 0.05 to 0.7, “c” is a number of 0.05 to 1.0, and a+b+c is 1.05 to 1.9.
Examples of the C
3
-C
5
cyanoalkyl group represented by R
1
include cyanoethyl, cyanopropyl, cyanobutyl, 2-cyanopropyl, 2-cyanobutyl, 3-cyanobutyl, and 2-methyl-2-cyanopropyl. Of these, cyanoethyl is preferred.
Examples of the monovalent C
2
-C
6
hydrocarbon group having an aliphatic unsaturated bond represented by R
2
include alkenyl groups such as vinyl and allyl, with vinyl being preferred.
R
3
is selected from substituted or unsubstituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, other than R
1
and R
2
, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl and cyclohexyl, aryl groups such as phenyl, aralkyl groups such as benzyl and phenylethyl, and halogenated monovalent hydrocarbon groups such as chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, 1,1,1-trifluorohexyl and 3-chloropropyl. Of these, methyl is preferred.
The letter “a” representative of the content of cyanoalkyl groups in the average compositional formula (I) is from 0.2 to 0.95, and preferably from 0.3 to 0.6. Too low a cyanoalkyl content leads to a lower concentration of nitrile groups in the polymer, which may lead to a reduced dielectric constant. With too high a cyanoalkyl content, the content of aliphatic unsaturation-bearing monovalent hydrocarbon groups (represented by “b”) may be relatively reduced, resulting in insufficient cure.
The letter “b” representative of the conten
Kudo Muneo
Yamaya Masaaki
Moore Margaret G.
Shin-Etsu Chemical Co. , Ltd.
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