Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-02-07
2004-03-02
Berman, Susan (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S172000, C528S012000, C528S017000, C528S018000, C528S021000, C528S032000, C528S033000
Reexamination Certificate
active
06699918
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organopolysiloxane composition with two curing mechanisms, namely photopolymerizability and condensation curability.
2. Description of the Prior Art
The curing of an organopolysiloxane by heating in the presence of an organic peroxide, to produce a silicone rubber elastic body with superior heat resistance, low temperature resistance, weather resistance and electrical characteristics, is well known. Furthermore, ultraviolet light curable organopolysiloxane compositions which are cured by irradiation with light in the presence of a photopolymerization initiator are also known, and examples of such compositions are those disclosed in Japanese Post-Examination Publication (kokoku) No. 52-40334 (JP52-40334B) corresponding to U.S. Pat. No. 4,064,027 and Japanese Laid-open Publication (kokai) No. 60-104158 (JP60-104158A), which incorporate a vinyl group containing polysiloxane and a mercapto group containing polysiloxane, and are cured using a light initiated radical addition reaction. However, these compositions have an odor associated with the mercapto group and are corrosive towards metals, and consequently the uses of such compositions are limited.
Furthermore, additional examples of compositions which undergo curing on light irradiation are the compositions disclosed in Japanese Post-Examination Publication (kokoku) No. 53-36515 (JP53-36515B) corresponding to GB 1323869B and Japanese Laid-open Publication (kokai) No. 60-215009 (JP60-215009A), corresponding to U.S. Pat. No. 4,675,346 which comprise an acryloyl group containing polysiloxane, a photopolymerization initiator and a sensitizer. However, in order to obtain a rubber elastic body, these compositions require the use of high molecular weight linear polymers, and so the relative quantity of acryloyl groups located at the terminals becomes extremely small, resulting in a composition of poor curability, and furthermore the surface portions of the composition in contact with the air undergo almost no curing due to the curing inhibiting effect of oxygen. Consequently, only resin-producing compositions with comparatively large quantities of acryloyl groups were able to be developed, and their cured products were unsatisfactory as rubber elastic bodies.
In order to overcome the drawbacks of the acryloyl group containing polysiloxane compositions described above, adhesives with two curing mechanisms, namely curing due to photopolymerization and curing due to atmospheric moisture (condensation curing), have been proposed and developed. A specific example is the composition disclosed in Japanese Post-Examination Publication (kokoku) No. 6-51774 (JP6-51774B) corresponding to U.S. Pat. No. 4,528,081 which incorporates an organopolysiloxane with an acryloyl group or a methacryloyl group and a hydrolysable group at the terminals, a condensation curing catalyst, and a photopolymerization initiator. However, this composition displays poor adhesiveness to a substrate immediately following irradiation with ultraviolet light, and is consequently difficult to use as an ultraviolet curing adhesive.
SUMMARY OF THE INVENTION
In consideration of the circumstances described above, an object of the present invention is to provide an organopolysiloxane composition with two curing mechanisms, namely photopolymerizability and condensation curability, which displays superior adhesiveness, and in particular superior adhesiveness relative to a substrate immediately following irradiation with ultraviolet light.
As a result of intensive investigations of compositions with superior adhesiveness, and in particular superior adhesiveness immediately following irradiation with ultraviolet light, the inventors of the present invention discovered that the reason the composition disclosed in Japanese Post-Examination Publication (kokoku) No. 6-51774 (JP6-51774B) displayed poor adhesiveness relative to a substrate immediately following irradiation with ultraviolet light, was that in one of the curing components of the composition, the part responsible for the photopolymerization, i.e., the acryloyl group or the methacryloyl group, and the part responsible for the condensation curing, i.e., the alkoxy group or the acryloxy group, were bonding together to the same single silicon atom. Consequently in the present invention, the inventors discovered that by using, as one constituent of an organopolysiloxane composition, an organosilicon compound with at least two silicon atoms within a single molecule and with a photopolymerizable group and a condensation curable group bonded to different silicon atoms, the adhesiveness of the composition relative to a substrate immediately following irradiation with ultraviolet light was able to be improved, and as a result were able to complete the present invention.
In other words, the present invention provides an organopolysiloxane composition comprising (A) 100 parts by weight of an organopolysiloxane represented by the general formula (1) shown below
wherein, each R
1
represents, independently, a substituted or unsubstituted monovalent hydrocarbon group of 1 to 15 carbon atoms, and a represents an integer from 10 to 3000; (B) 0.1 to 30 parts by weight of an organosilicon compound represented by the
general formula (2) shown below
wherein, each R
2
represents, independently, a hydrogen atom, a phenyl group or a halogenated phenyl group, each R
3
represents, independently, a hydrogen atom or a methyl group, each R
4
represents, independently, a substituted or unsubstituted monovalent hydrocarbon group of 1 to 10 carbon atoms, X represents a hydrolysable group, each Z
1
represents, independently, —R
5
—, —R
5
O— or —R
5
(CH
3
)
2
SiO— where each R
5
represents, independently, a substituted or unsubstituted bivalent hydrocarbon group of 1 to 10 carbon atoms, Z
2
represents an oxygen atom or a substituted or unsubstituted bivalent hydrocarbon group of 1 to 10 carbon atoms, m represents 0, 1 or 2, and n represents 0, 1 or 2);
(C) an effective quantity of a condensation curing catalyst; and
(D) 0.01 to 10 parts by weight of a photopolymerization initiator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As follows is a more detailed description of an organopolysiloxane composition according to the present invention.
(A) Organopolysiloxane Represented by the General Formula (1)
In the organopolysiloxane represented by the general formula (1), the R
1
groups may be the same or different and each group represents a substituted or unsubstituted monovalent hydrocarbon group of 1 to 15 carbon atoms, and preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and a represents an integer from 10 to 3000, and preferably from 50 to 1800.
In the general formula (1), suitable examples of substituted monovalent hydrocarbon groups represented by the symbol R
1
include halogenated alkyl groups, e.g., having 1-6 carbon atoms, such as chloromethyl groups, 2-chloroethyl groups, 2-bromoethyl groups, 1,1-dichloropropyl groups, 3-chloropropyl groups and 3,3,3-trifluoropropyl groups; whereas suitable examples of unsubstituted monovalent hydrocarbon groups include alkyl groups, e.g., having 1-6 carbon atoms, such as methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, pentyl groups, hexyl groups, and cyclohexyl groups; alkenyl groups, e.g., having 1-6 carbon atoms, such as vinyl groups and allyl groups; aryl groups, e.g., having 6-10 carbon atoms, such as phenyl groups and tolyl groups; and aralkyl groups, e.g., having 7-10 carbon atoms, such as benzyl groups or phenylethyl groups. Of these groups, substituted or unsubstituted alkyl groups of 1 to 6 carbon atoms or phenyl groups are preferred, and methyl groups, ethyl groups, phenyl groups and 3,3,3-trifluoropropyl groups are particularly desirable.
Specific structural examples of organopolysiloxanes represented by the general formula (1) are shown below, although the present invention is in no way limited to the examples shown.
whe
Goto Tomoyuki
Inoue Yoshifumi
Ozai Toshiyuki
Berman Susan
Shin-Etsu Chemical Co. , Ltd.
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