Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-01-27
2001-07-31
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S093000, C524S095000, C524S267000, C524S265000, C524S492000, C524S493000
Reexamination Certificate
active
06268416
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a silicone rubber adhesive film and to methods for adhering metal substrates to glass substrates.
Silicone rubber adhesive films are known. For example, Japanese Official Patent Publication (Kokoku) Heisei 7-119394 discloses a silicone rubber adhesive film prepared from an organopolysiloxane rubber and a wet method hydrophobized reinforcing silica with a curing accelerator. The silicone rubber adhesive film is simple to handle, possesses excellent workability, and is suitable for firmly securing together plates which have smooth surfaces and are made of such materials as glass, metal, etc. Furthermore, since the silicone rubber adhesive film can fix together glass and metal plates, it can be advantageously used as an adhesive for attaching knobs to glass entrance doors or to glass windows for buildings, for attaching mirrors (so called inner mirrors) to automobile windshield, etc. However, the adhesive strength of the silicone rubber adhesive film depends on the degree of its curing, and therefore there may be significant variations in the strength of the connections between structural elements secured with the use of this adhesive.
It is an object of the present invention to provide a colored silicone rubber adhesive film which is easily handled, possesses excellent workability, and most important, makes it possible to verify the degree and the point of completion of the curing in the silicone rubber adhesive film. When the latter is used for bonding various substrates together, it produces adhesive connections with improved uniformity.
Another object of the present invention is to provide methods for adhering metals substrates to glass substrates with the use of the colored silicone rubber adhesive film.
As a results of careful studies aimed at the solution of the problems described above, the present inventors have found certain organic pigments when present in a specific transparent silicone rubber adhesive film creates a colored film. The colored silicone rubber film become colorless upon subsequent heating and curing. This feature is used to verify the degree of curing, so that the moment at which the adhesive becomes completely colorless, curing completion is indicated. Furthermore, the inventors have discovered that the colored silicone rubber adhesive film produces bonded structures with improved uniformity in adhesive strength.
SUMMARY OF THE INVENTION
The present invention provides a colored silicone-rubber adhesive film composition comprising:
(A) 100 parts by weight of an organopolysiloxane with an average unit formula R
a
SiO
(4−a)/2
, where R is a substituted or unsubstituted hydrocarbon group with the provision that at least two R groups are alkenyl groups, and a is a number between 1.9 and 2.1;
(B) 30 to 150 parts by weight of a wet method hydrophobized reinforcing silica having a specific surface area exceeding 200 m
2
/g, consisting essentially of SiO
4/2
units and organopolysiloxane units selected from the group consisting of R
3
SiO
1/2
units, R
2
SiO
2/2
units, RSiO
3/2
units, and mixtures thereof, where R is the same as defined above, wherein the mole ratio of the organopolysiloxane units to the SiO
4/2
units is within a range of 0.08 to 2.0;
(C) 0.1 to 10 parts by weight of an organohydridopolysiloxane comprising at least one silicon-bonded hydrogen atom;
(D) a pigment selected from the group of azo pigments and anthroquinone pigments present in an amount sufficient for coloring a silicone rubber adhesive film composition;
(E) a curing accelerator in an amount sufficient to cure the silicone rubber adhesive film composition;
wherein said colored silicone rubber adhesive film composition has a tensile strength of 1.5 kg/cm
2
to 5.0 kg/cm
2
at 25° C.
The inventors also provide a method of adhering a metal substrate to a glass substrate comprising:
a) coating the surface of a metal substrate with a primer composition comprising a organosilicon compound selected from the group of silanes and organosiloxane oligimers having an alkoxy group to form a primer layer;
b) laminating said primer layer with the colored silicone rubber adhesive film;
c) bringing the surface of said colored silicone rubber adhesive film into contact with a glass substrate;
d) curing said colored silicone rubber adhesive film composition at a temperature above 80° C. until the said colored silicone rubber adhesive film composition becomes colorless.
In another embodiment of adhering a metal substrate to a glass substrate, a method is provided comprising:
a) coating the surface of a metal substrate with a primer composition comprising,
i) an organosilicon compound having an alkoxy group selected from the group of silanes and organosiloxane oligimers, and
ii) a pigment selected from the group of azo pigments and anthroquinone pigments to form a colored primer layer on the surface of said metal substrate;
b) laminating said colored primer layer with a silicone rubber adhesive film composition comprising,
(A) 100 parts by weight of an organopolysiloxane with an average unit formula R
a
SiO
(4−a)/2
, where R is a substituted or unsubstituted hydrocarbon group with the provisio that at least two R groups are alkenyl groups, and a is a number between 1.9 and 2.1;
(B) 30 to 150 parts by weight of a wet method hydrophobized reinforcing silica having a specific surface area exceeding 200 m
2
/g, consisting essentially of SiO
4/2
units and organopolysiloxane units selected from the group consisting of R
3
SiO
1/2
units, R
2
SiO
2/2
units, RSiO
3/2
units, and mixtures thereof, where R is the same as defined above, wherein the mole ratio of the organopolysiloxane units to the SiO
4/2
units is within a range of 0.08 to 2.0;
(C) 0.1 to 10 parts by weight of an organohydridopolysiloxane comprising at least one silicon-bonded hydrogen atom;
(D) a curing accelerator in an amount sufficient to cure the silicone rubber adhesive film composition;
wherein said silicone rubber adhesive film composition has a tensile strength of 1.5 kg/cm
2
to 5.0 kg/cm
2
in an uncured state at 25° C.;
c) maintaining contact between the silicone rubber adhesive film and the colored primer layer for at least one hour to form a colored silicone rubber adhesive layer;
d) bringing the surface of said colored silicone rubber adhesive film into contact with a glass substrate, and
e) curing said colored silicone rubber adhesive film by heating at a temperature above 80° C. until the film becomes colorless.
REFERENCES:
patent: 4614758 (1986-09-01), Schwabe et al.
patent: 4918126 (1990-04-01), Matsushita et al.
patent: 5366768 (1994-11-01), Kasari et al.
patent: 7-119394 (1995-12-01), None
Dow Corning Toray Silicone Company, Ltd.
Rajguru U. K.
Seidleck James J.
Zombeck Alan
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