Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2002-03-06
2004-11-09
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...
C528S032000, C528S043000
Reexamination Certificate
active
06815520
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an addition curing type silicone resin composition useful in a variety of fields including electrical and electronic equipment, OA equipment and precision instruments.
2. Description of the Prior Art
Silicone resins are widely known as resins which display superior properties of heat resistance, cold resistance, electrical insulation, weather resistance, water repellency and transparency, and as such are widely used in a variety of fields including electrical and electronic equipment, OA equipment, motor vehicles, precision instruments, and building materials.
Furthermore in recent years, particularly transparent organic materials have been proposed as a potential alternative to inorganic glass materials in fields such as the manufacture of optical lenses, because they offer superior workability, and are lightweight, low cost and impact resistant. Amongst such transparent organic materials, silicone based resins are superior to other organic materials in terms of transparency and associated optical characteristics, and as such offer one of the most promising alternatives to inorganic glass materials and the like.
Amongst silicone resins, addition curing type silicone resin compositions such as those disclosed in Japanese Laid-open patent publication (kokai) No. 11-1619 (JP11-1619A) offer certain advantages, including being solventless and consequently offering superior moldability to solvent based condensation curing silicone materials such as silicone varnish, and moreover being more environmentally friendly due to the fact that they contain almost no solvent. Furthermore, because of the high degree of moldability they offer, silicone resins are also used in the production of key pads, although to enable their use in small, lightweight devices such as mobile telephones, the key pad member must be very thin, and as a result, further strength improvements in these key pad compositions are required.
However, silicone resin compositions such as those disclosed in Japanese Laid-open patent publication (kokai) No. 11-1619 (JP11-1619A) do not offer sufficient strength to enable their use in the type of applications described above.
SUMMARY OF THE INVENTION
In order to resolve the issues described above, an object of the present invention is to provide an addition curing type silicone resin composition which on curing produces a cured product which is transparent, displays good strength, and particularly good flexural strength, and moreover also displays a high degree of hardness.
As a result of intensive investigations aimed at resolving the aforementioned issues, the inventors of the present invention discovered that in order to increase the strength, particularly the flexural strength, and the hardness of a cured product, the cross linking density of the siloxane must be increased, and the &pgr;—&pgr; interactions between aromatic rings must also be considered as an important factor. The inventors also discovered that the aforementioned object of the present invention could be achieved by addition curing of specific organopolysiloxanes with a phenyl group and an alkenyl group, and specific organohydrogenpolysiloxanes with a phenyl group, and were consequently able to complete the present invention.
In other words, the present invention provides an addition curing type silicone resin composition comprising:
(A) 100 parts by weight of an organopolysiloxane represented by the average composition formula (1):
R
1
a
R
2
b
R
3
c
SiO
(4−a−b−c)/2
(1)
(wherein, R
1
represents a phenyl group, R
2
represents an alkenyl group of 2 to 10 carbon atoms, R
3
represents a monovalent group selected from the group consisting of monovalent hydrocarbon groups with the exception of a phenyl group and alkenyl groups, a hydroxyl group and alkoxy groups, and a, b and c are positive numbers which satisfy the requirements 0.5≦a≦1.0, 0.2≦b≦0.5, 0.2≦c≦0.8 and 1.0<a+b+c<2.0), which incorporates a phenyl group and at least two alkenyl groups within a single molecule, and in which the combined proportion of Si atoms within ≡Si—R
2
groups and RSiO
3/2
units (wherein, R represents either one of R
1
and R
3
as defined above) relative to the total number of Si atoms is at least 70 mol %;
(B) 1 to 100 parts by weight of an organohydrogenpolysiloxane represented by the average composition formula (2):
R
4
d
H
c
R
5
f
SiO
(4−d−e−f)/2
(2)
(wherein, R
4
represents a phenyl group, R
5
represents a monovalent group selected from the group consisting of monovalent hydrocarbon groups with the exception of a phenyl group, a hydroxyl group and alkoxy groups, and d, e and f are positive numbers which satisfy the requirements 0.4≦d≦1.0, 0.5≦e≦0.8, 0.7≦f≦1.2 and 1.8<d+e+f<3.0), which incorporates a phenyl group and at least two SiH groups within a single molecule; and
(C) an effective quantity of a hydrosilylation reaction catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As follows is a more detailed description of the present invention.
Constituent (A)
Constituent (A), which is one of the essential constituents of an addition curing type silicone resin composition of the present invention, is an organopolysiloxane represented by the average composition formula (1):
R
1
a
R
2
b
R
3
c
SiO
(4−a−b−c)/2
(1)
(wherein, R
1
represents a phenyl group, R
2
represents an alkenyl group of 2 to 10 carbon atoms, R
3
represents a monovalent group selected from the group consisting of monovalent hydrocarbon groups with the exception of a phenyl group and alkenyl groups, a hydroxyl group and alkoxy groups, and a, b and c are positive numbers which satisfy the requirements 0.5≦a≦1.0, 0.2≦b≦0.5, 0.2≦c≦0.8 and 1.0<a+b+c<2.0), which incorporates a phenyl group and at least two alkenyl groups within a single molecule, and in which the combined proportion of Si atoms within ≡Si—R
2
groups and RSiO
3/2
units (wherein R represents either R
1
or R
3
) relative to the total number of Si atoms is at least 70 mol %.
In the average composition formula (1), as is evident from the relationship 1.0<a+b+c<2.0 (namely, 2.0/2<(4−a−b−c)/2<3.0/2), this organopolysiloxane is a branched type structure or a three dimensional network structure with either one type, or two or more types, of RSiO
3/2
units and SiO
2
units within the molecule, and the alkenyl group represented by the R
2
of the ≡Si—R
2
group undergoes a hydrosilylation reaction with the hydrogen of the organohydrogenpolysiloxane represented by the average composition formula (2), thereby forming further branching or three dimensional network structures. Values of a, b and c which satisfy the requirement 1.3<a+b+c<1.7 are preferred. Furthermore, even if this organopolysiloxane incorporates R
2
SiO
3/2
units, the terminals may be blocked with R
3
3
SiO
1/2
units.
In the average composition formula (1), R
1
represents a phenyl group and R
2
represents an alkenyl group of 2 to 10 carbon atoms. Examples of suitable alkenyl groups include vinyl groups, allyl groups, propenyl groups, isopropenyl groups and butenyl groups, and of these, vinyl groups are preferred.
Furthermore, in the average composition formula (1), R
3
represents a monovalent group selected from the group consisting of monovalent hydrocarbons group with the exception of a phenyl group and alkenyl groups, a hydroxyl group and alkoxy groups. Examples of such hydrocarbon groups, which may be the same or different, include substituted or unsubstituted monovalent hydrocarbons of 1 to 20, and preferably 1 to 10 carbon atoms. Specific examples of such hydrocarbon groups include alkyl groups such as methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, tert-butyl groups and hexyl groups; other saturated hydrocarbon groups including cycloalkyl gr
Itagaki Akinari
Yamaya Masaaki
Yoneda Yoshinori
Moore Margaret G.
Shin-Etsu Chemical Co. , Ltd.
LandOfFree
Addition curing type silicone resin composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Addition curing type silicone resin composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Addition curing type silicone resin composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3343261