Curable silicone composition

The present invention pertains to a curable silicone composition comprised of (A) an organopolysiloxane represented by the formula ##STR1## wherein R.sup.1 is a monovalent hydrocarbon group other than an alkenyl group; R.sup.2 is a monovalent hydrocarbon group other than an alkenyl group or hydrogen; R.sup.3 is an organic group that contains an epoxy group or an alkoxysilylalkyl group with the proviso that at least one R.sup.3 group is an organic group containing an epoxy group; a is either 0 or a positive number; b is a positive number; c is a positive number; a/c has a value of between 0 to 4, b/c has a value of between 0.05 to 4, and (a+b)/c has a value of between 0.2 to 4; and (B) a curing compound selected from curing agents or curing catalysts. The curable silicone composition of the present invention has superior curing properties and is capable of forming a hardened silicone material with superior flexibility and heat resistance after curing.

BACKGROUND OF THE INVENTION 
Because of their superior adhesive properties, bonding properties, 
environmental resistance, and electrical properties after the silicone is 
hardened curable silicone compositions are used for electric and 
electronic fillers, adhesives for electric and electronic applications, 
coating compositions, and coating materials for rubber. Silicone 
compositions curable by a condensation-reaction which undergo curing by a 
dehydration-condenstion reaction of silanol groups, dehydrogenation 
between a silanol group and a hydrogen bonded to a silicon atom, dealcohol 
reaction between a silanol group and silicon atom bonded alkoxy group, and 
silicone compositions curable by an adduct reaction which undergo curing 
by an adduct reaction between the silicon atom, hydrogen, and fatty acid 
unsaturated groups in the presence of hydrosilylation reaction catalysts 
are known in the art. 
However, in the silicone compositions curable by a condensation reaction, 
the curing requires a very long time and the curing property is inferior; 
in the case of silicone compositions curable by an adduct reaction, curing 
does not progress in the presence of adduct reaction inhibitors such as 
sulfur and soldering flux, and the surface of the composition is less 
likely to be hardened because of oxygen. In addition, in general, the heat 
resistance of the curable silicone composition is inferior after curing. 
For this reason, various types of curable silicone compositions with 
improved curing properties have been suggested. Curable silicone 
compositions comprised of a hydrolysate of an organic silane containing an 
epoxy group and ammonium perchlorate are disclosed in Japanese Kokai 
Patent Application No. Sho 56[1981]-72054 and curable silicone 
compositions comprised of an organopolysiloxane containing at least two 
epoxy groups in a single molecule, organopolysiloxane containing at least 
two amino groups in a single molecule, and an epoxy curing catalyst are 
disclosed in Japanese Kokai Patent Application No. Sho 60[1985]-179417. 
However, the curing properties of curable silicone compositions suggested 
in Japanese Kokai Patent Application No. Sho 56[1981]-72054 and Japanese 
Kokai Patent Application No. Sho 60[1985]-179417 are insufficient, and the 
flexibility and heat resistance of the cured silicone material are 
inferior. 
It is an object of the present invention is to produce a curable silicone 
composition with superior curing properties that forms a hard silicone 
material with superior flexibility and heat resistance after curing. 
SUMMARY OF THE INVENTION 
The present invention pertains to a curable silicone composition comprised 
of (A) an organopolysiloxane represented by the formula 
##STR2## 
wherein R.sup.1 is a monovalent hydrocarbon group other than an alkenyl 
group; R.sup.2 is a monovalent hydrocarbon group other than an alkenyl 
group or hydrogen; R.sup.3 is an organic group that contains an epoxy 
group or an alkoxysilylalkyl group with the proviso that at least one 
R.sup.3 group is an organic group containing an epoxy group; a is either 0 
or a positive number; b is a positive number; c is a positive number; a/c 
has a value of between 0 to 4, b/c has a value of between 0.05 to 4, and 
(a+b)/c has a value of between 0.2 to 4; and (B) a curing compound 
selected from curing agents or curing catalysts. 
The curable silicone composition of the instant invention is mainly 
comprised of an organopolysiloxane made of monofunctional siloxane units 
(M units) and quaternary functional siloxane units (Q units ) and has 
superior curing properties that forms a hardened silicone material with 
superior flexibility and heat resistance after curing. 
THE INVENTION 
The present invention pertains to a curable silicone composition comprised 
of (A) an organopolysiloxane represented by the formula 
##STR3## 
wherein R.sup.1 is a monovalent hydrocarbon group other than an alkenyl 
group; R.sup.2 is a monovalent hydrocarbon group other than an alkenyl 
group or hydrogen; R.sup.3 is an organic group that contains an epoxy 
group or an alkoxysilylalkyl group with the proviso that at least one 
R.sup.3 group is an organic group containing an epoxy group; a is either 0 
or a positive number; b is a positive number; c is a positive number; a/c 
has a value of between 0 to 4, b/c has a value of between 0.05 to 4, and 
(a+b)/c has a value of between 0.2 to 4; and (B) a curing compound 
selected from curing agents or curing catalysts. 
The organopolysiloxane, component (A), is the primary component of the 
present invention and is represented by the formula: 
##STR4## 
R.sup.1 is a monovalent hydrocarbon group other than an alkenyl group. R1 
may be exemplified by alkyl groups such as methyl group, ethyl group, 
propyl group, butyl group, pentyl group; aryl groups such as phenyl group, 
tolyl group, xylyl group; aralkyl groups such as benzyl group and 
phenethyl group; and substituted alkyl groups such as chloromethyl group 
and 3,3,3-trifluoropropyl group. R.sup.2 is selected from hydrogen or a 
monovalent hydrocarbon group other than an alkenyl group. R.sup.2 may be 
exemplified by hydrogen or alkyl groups such as methyl group, ethyl group, 
propyl group, butyl group, and pentyl group; aryl groups such as phenyl 
group, tolyl group, xylyl group; aralkyl groups such as benzyl group and 
phenethyl group; and substituted alkyl groups such as chloromethyl group 
and 3,3,3-trifluoropropyl group. R.sup.3 is an organic group that contains 
an epoxy group or alkoxysilylalkyl group with the proviso that at least 
one of R.sup.3 is an organic group containing an epoxy group. R.sup.3 may 
be exemplified by organic groups containing an epoxy group, such as 
glycidoxyethyl group, glycidoxypropyl group, glycidoxybutyl group, 
3,4-epoxycyclohexylethyl group, 3,4- epoxycyclohexylpropyl group, 
3,4-epoxynorbornaylethyl group, 2- 
(3,4-epoxy-3-methylcyclohexyl)-2-methylethyl group; and alkoxysilylalkyl 
groups that provide an adhesive property to the composition of the present 
invention, such as trimethoxysilylethyl group, triethoxysilylpropyl group, 
trimethoxysilylbutyl group, triethoxysilylethyl group, 
triethoxysilylpropyl group, tripropoxysilylethylene, 
methyldimethoxysilylethyl group, and methyldimethoxysilylpropyl group. 
Furthermore a is either 0 or a positive number that indicates the number of 
monofunctional siloxane units (M units) that do not include an organic 
group containing an epoxy group or alkoxysilylalkyl group. b is a positive 
number that indicates the number of monofunctional siloxane units (M 
units) having an organic group containing an epoxy group or an 
alkoxysilylalkyl group. c is a positive number that indicates the number 
of quaternary functional siloxane units (Q units). For each of the ratios, 
a/c is a number between 0 to 4, b/c is a number between 0.05 to 4, and 
(a+b)/c is a number between 0.2 to 4. This is because it is not possible 
to include more than four of the monofunctional siloxane units (M units) 
per quaternary functional siloxane unit (Q unit), and ill order to produce 
a hardened silicone material with superior flexibility and heat resistance 
after curing, at least 0.05 monofunctional siloxane unit (M unit) 
containing an organic group containing epoxy group or alkoxysilylalkyl 
group per quaternary functional siloxane unit (Q unit) is necessary. 
The organopolysiloxane (A) remains in a liquid state or a solid state at 
room temperature, and the molecular weight is not especially limited, but 
from the standpoint of superior curing properties, a range of 500-500,000 
is desirale. The organopolysiloxane (A) described above can be produced 
by, for example, performing an adduct reaction with the organopolysiloxane 
represented by the formula: 
##STR5## 
and an unsaturated aliphatic hydrocarbon containing an epoxy group, and an 
appropriate amount of alkoxysilylalkene in the presence of a 
hydrosilylation reaction catalyst; wherein R.sup.1 is a monovalent 
hydrocarbon group other than an alkenyl group; d is either 0 or a positive 
number; e is a positive number; f is a positive number; d/f has a value of 
between 0 to 4, e/f has a value of between 0.05 to 4, and (d+e)/f has a 
value of between 0.2 to 4. 
The curing compound, component (B), is a component that hardens the 
organopolysiloxane component (A), and component (B) is not especially 
limited as long as the material is a curing agent or curing catalyst that 
is capable of curing the epoxy resin. Useful curing agents may be 
exemplified by phenolic compounds, carboxylic acid compounds, acid 
anhydrides, amine compounds, compounds containing alkoxy groups, or 
mixtures thereof or partial reaction products thereof. Useful curing 
catalysts may be exemplified by tertiary amine compounds such as 
imidazole; quaternary amine compounds; phosphorus compounds such as 
phosphine; aluminum compounds such as organic aluminum; and zirconium 
compounds such as organic zirconium compounds. Furthermore, in the 
composition of the present invention, either a curing agent or curing 
catalyst or a combination of curing a agent and a curing catalyst can be 
used. 
The mixing ratio of component (B) is not especially limited, but it is 
desirable to add 0.1-500 parts by weight per 100 parts by weight of 
component (A). This is because when the mixing ratio of component (B) is 
less than 0.1 part by weight per 100 parts by weight of component (A), the 
curing reaction is less likely to be initiated, and when the amount 
exceeds 500 parts by weight, a sufficient degree of the curing reaction 
fails to occur. 
In addition, the curable silicone composition of the present invention 
mainly composed of component (A) and component (B) may include fillers 
such as aerosol silica, crystalline silica, fused silica, wet silica, 
titanium oxide, zinc carbonate, calcium carbonate, iron oxide, and carbon 
black, fatty acid esters such as stearic acid ester, and palmitic acid 
ester, metal salts, ester-based waxes, and plasticizers. 
The curable silicone compositions of the present invention has superior 
curing properties and forms a hard silicone material with a superior 
flexibility and heat resistance after curing; therefore, it can be used 
effectively for coating compositions, coating agents for electric and 
electronic parts, adhesives, sealers for electric and electronic parts, 
sealing agents used for high temperature areas such as automobile engines 
and furthermore for a composition that provides flexibility in the curable 
resin compositions. 
So that those skilled in the art can understand and appreciate the 
invention taught herein, the following examples are presented, being it 
understood that these examples should not be used to limit the scope of 
this invention found in the claims attached hereto. 
In the following examples the value of the viscosity in application 
examples is the value measured at 25.degree. C., and curable silicone 
compositions were cured by heating at 150.degree. C. for 3 hours. 
Furthermore, measurement of physical properties of the hardened silicone 
material was carried out as described below. 
Heat resistance: A small piece of hardened silicone was heated in air at a 
rate of temperature increase of 10.degree. C./min by thermogravimetric 
analysis (TGA), and is shown as the residual (wt %) at 850.degree. C. 
Flexibility: Both ends of a hardened silicone material molded to form a 1/4 
inch.times.1/2 inch.times.4 inch bar were fixed, then a 5 kg weight was 
hung from the center of the hardened silicone material, and the warping at 
the center area was measured. When the warping was less than 0.5 cm, it is 
classified as x, when 0.5-1 cm, it is classified as .DELTA., an when it 
exceeds 1 cm, it is classified as 0. 
Hardness: A hardened silicone material molded to form a disc 2 inches in 
diameter.times.1/10 inch was measured by a Barcol 935 hardness meter.

PREATION EXAMPLE 1 
An organopolysiloxane shown by the formula 
EQU [CH.sub.3).sub.3 SiO.sub.1/2 ].sub.0.8 [(CH.sub.3).sub.2 HSiO.sub.1/2 
].sub.0.7 (SiO.sub.4/2).sub.1.0 
(viscosity 105 centipoise, silicon-bonded hydrogen content 0.40 wt %) was 
reacted with an excess amount of allyl glycidyl ether in toluene using 
chloroplatinate as a catalyst. An organopolysiloxane having the formula: 
##STR6## 
was produced. The viscosity of the organopolysiloxane produced was 520 
centipoise, and the epoxy equivalence was 420. 
PREATION EXAMPLE 2 
An organopolysiloxane shown by the formula: 
EQU [CH.sub.3).sub.2 HSiO.sub.1/2 ].sub.1.8 (SiO.sub.4/2).sub.1.0 
(viscosity 46 centipoise, silicon-bonded hydrogen content 0.92 wt %) was 
reacted with an excess amount of allyl glycidyl ether in toluene with 
chloroplatinate as a catalyst. An organopolysiloxane having the formula: 
##STR7## 
was produced. The viscosity of the organopolysiloxane produced was 610 
centipoise, and the epoxy equivalence was 370. 
PREATION EXAMPLE 3 
A viscous organopolysiloxane shown by the formula 
EQU [CH.sub.3).sub.3 SiO.sub.1/2 ].sub.0.7 [(CH.sub.3).sub.2 HSiO.sub.1/2 
].sub.0.5 (SiO.sub.4/2).sub.1.0 
(silicon-bonded hydrogen content 0.33 wt %) was reacted in toluene with an 
excess amount of allyl glycidyl ether with chloroplatinate as a catalyst. 
An organopolysiloxane having the formula: 
##STR8## 
was produced. The organopolysiloxane produced had a semi transparent brown 
color, and the epoxy equivalence was 1100. 
PREATION EXAMPLE 4 
An organopolysiloxane shown by the formula 
EQU [(CH.sub.3).sub.3 SiO.sub.1/2 ].sub.0.6 [(CH.sub.3).sub.2 HSiO.sub.1/2 
].sub.0.1 (SiO.sub.4/2).sub.1.0 
(silicon-bonded hydrogen content 0.09 wt %) was reacted in toluene with an 
excess amount of allyl glycidyl ether with chloroplatinate as a catalyst. 
An organopolysiloxane having the formula 
##STR9## 
was produced. The organopolysiloxane produced had a semitransparent brown 
color, and the epoxy equivalence was 1290. 
PREATION EXAMPLE 5 
An organopolysiloxane shown by the formula 
##STR10## 
(viscosity 46 centipoise, silicon-bonded hydrogen content 0.92 wt %) was 
reacted in toluene with an excess amount of 1,2-epoxy-4-vinylcyclosiloxane 
with chloroplatinate as a catalyst. An organopolysiloxane having the 
formula 
##STR11## 
was produced. The organopolysiloxane produced had a semitransparent brown 
color, the viscosity was 520 centipoise, and the epoxy equivalence was 
230. 
PREATION EXAMPLE 6 
An organopolysiloxane shown by the formula 
EQU [(CH.sub.3).sub.2 HSiO.sub.1/2 ].sub.4.0 (SiO.sub.4/2).sub.1.0 
(boiling point 190.degree. C., silicon-bonded hydrogen content 1.22 wt %) 
was reacted in toluene with an excess amount of allyl glycidyl ether with 
chloroplatinate as a catalyst, and organopolysiloxane having the formula: 
##STR12## 
below was produced. The organopolysiloxane produced was a semitransparent 
brown color, the viscosity was 54 centipoise, and the epoxy equivalence 
was 205. 
PREATION EXAMPLE 7 
An organopolysiloxane shown by the formula 
EQU [(CH.sub.3).sub.2 HSiO.sub.1/2 ].sub.1.8 (SiO.sub.4/2).sub.1.0 
(viscosity 46 centipoise, silicon-bonded hydrogen content 0.92 wt %) was 
reacted in toluene with a mixture composed of allyl glycidyl ether and 
allyltrimethoxysilane=1:1 with chloroplatinate as a catalyst. An 
organopolysiloxane having the formula 
##STR13## 
was produced. The organopolysiloxane produced had a semitransparent yellow 
color, and the viscosity was 200 centipoise. 
EXAMPLE 1 
Organopolysiloxanes produced in the Preparation examples, 
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3- or 
4-methylhexahydrophthalic anhydride, and 2,4,6-(trisdimethyl- 
aminomethyl)phenol were uniformly mixed in the weight ratio listed in 
Table I, and curable silicone compositions were produced. These curable 
silicone compositions were cured, and the properties of the hardened 
silicone materials were evaluated. These results are shown in Table I. 
Also, the hardness of the curable silicone composition mixed with the 
organopolysiloxane prepared in Preparation Example 2 after curing was 55. 
COMATIVE EXAMPLE 1 
The organopolysiloxane was omitted, and a curable epoxy resin composition 
was prepared in the weight ratio shown in Table I. The curable epoxy resin 
composition was cured as in Example 1, and physical properties of the 
hardened material were evaluated. Results are shown in Table I. 
Also, the hardness of the hardened material was 55, and it was confirmed 
that no differences existed in the degree of hardness from the hardened 
material measured in Example 1. 
TABLE I 
__________________________________________________________________________ 
Type of Example 1 Comparative 
organopolysiloxane 
A B C/F 
D/G 
E E Example 1 
__________________________________________________________________________ 
Organopolysiloxane 
100 100 95/5 
95/5 
100 50 -- 
A* -- -- -- -- -- 50 100 
B* 37.6 
42.7 
14.4 
12.2 
40.5 
76.6 
120.5 
C* 1 1 1 1 1 1 1 
Flexibility 
.largecircle. 
.largecircle. 
.largecircle. 
.DELTA. 
.DELTA. 
.DELTA. 
X 
Residual (wt %) 
33 25 55 63 27 11 0 
__________________________________________________________________________ 
*A: 3,4Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 
*B: 3or 4(Methylhexahydrophthalic anhydride 
*C: 2,4,6(Trisdimethylaminomethyl)phenol 
EXAMPLE 2 
In addition to the components of Example 1, a fused silica with an average 
grain diameter of 13 .mu.m was added, and a curable silicone composition 
was produced as in Example 1. The curable silicone composition produced 
was cured as in Example 1, and the physical properties of the hardened 
silicone material were measured. Results are shown in Table II. 
TABLE II 
______________________________________ 
Type of Example 2 
organopolysiloxane E E 
______________________________________ 
Organopolysiloxane 100 50 
A* -- 50 
B* 40.5 76.6 
Fused silica 137.5 169.9 
C* 1 1 
Flexibility .DELTA. .DELTA. 
Residual (wt %) 65 57 
______________________________________ 
*A: 3,4Epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate 
*B: 3or 4(Methylhexahydrophthalic anhydride 
*C: 2,4,6(Trisdimethylaminomethyl)phenol 
COMATIVE EXAMPLE 2 
The same components as used in Example 1 were used except the 
organopolysiloxane shown in the following formula was used, and a curable 
silicone composition was produced as before. The organopolysiloxane shown 
in the formula below separated out onto the surface during curing of said 
curable silicone composition, and it was not possible to evaluate the 
physical properties of the material. 
##STR14## 
The curable silicone composition of the present invention is composed of 
component (A) and component (B). Component (A) is an organopolysiloxane 
composed of monofunctional siloxane units (M units) containing an organic 
group containing an epoxy group and quaternary functional siloxane units 
(Q units). The curing properties of the silicone composition are superior, 
and a hardened silicone material having superior flexibility and heat 
resistance after curing can be obtained.