Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-06-01
2002-02-26
Dawson, Robert (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C528S901000, C528S031000, C528S014000, C525S106000, C156S327000
Reexamination Certificate
active
06350345
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a curable resin composition useful as a contact adhesive. The term “contact adhesive” as used herein means an adhesive capable of adhesion under pressure after standing for a certain period of time following application thereof to an adherend.
PRIOR ART
The so-called solvent type adhesives comprising a natural rubber or a diene compound polymer such as synthetic rubber, together with additives, such as a tackifier resin, a plasticizer and an antioxidant, as homogeneously dissolved in an organic solvent (the solid concentration being 20 to 35%) have so far been widely used as contact adhesives. Since, however, a large amount of an organic solvent is used in such solvent type adhesives, not only the cost of the solvent arises but also the organic solvent must be evaporated and removed, which raises problems from the viewpoint of working environment, protection against disasters and pollution. For solving such problems and providing adhesives comparable in performance to the conventional solvent type adhesives, solvent-free contact adhesives have been proposed in which a modified silicone polymer is used, as disclosed in Japanese Kokai Publication Hei-03-263478 and Japanese Kokai Publication Hei-07-258535.
However, the contact adhesive in which the modified silicone polymer disclosed in Japanese Kokai Publication Hei-03-263478 is used has problems in that it takes a fairly long time for a sufficient extent of tack to enable lamination to develop and that it is poor in workability because of its high viscosity. Japanese Kokai Publication Hei-07-258535 discloses a curable composition comprising a reactive silicon group-containing oxyalkylene polymer, an acrylic copolymer and a curing catalyst. However, it does not disclose the introduction of a hydrocarbon group into such a reactive silicon group-containing oxyalkylene polymer at a position close to the reactive silicon group. In Japanese Kokai Publication Hei-07-258535, it is proposed that a contact adhesive capable of developing tack in a short time, allowing laminating over a long period and showing good workability be prepared by the method disclosed therein. However, the period during which tack is retained is not longer than an hour, hence cannot be said to be sufficient for workers to effect lamination. The measures so far taken for prolonging the tack retention period comprise adjusting the cure rate by changing the catalyst species, increasing or decreasing the catalyst amount, and/or changing the terminal reactive silicon group content, among others. However, the prior art measures have a problem in that when the tack retention period is prolonged by adjusting the cure rate, the final bond strength decreases accordingly. Thus, it is an object of the present invention to provide a curable resin composition with a prolonged tack retention period without affecting the final bond strength.
SUMMARY OF THE INVENTION
The present inventors made intensive investigations in an attempt to solve the problems mentioned above and, as a result, found that when an alkyl group is introduced into a reactive silicon group-containing polyether oligomer at a position close to the reactive silicon group, the reactivity of the reactive silicon group is indirectly reduced and the tack retention period is prolonged without affecting the final bond strength. Based on this finding, the present invention has now been completed.
Thus, in a first aspect thereof, the present invention relates to a curable resin composition
which comprises (I) a reactive silicon group-containing polyether oligomer, (II) a copolymer comprising a molecular chain substantially composed of one or more acrylate ester monomer units and/or methacrylate ester monomer units, and (III) an accelerator,
said reactive silicon group-containing polyether oligomer having, within the molecule thereof, a partial structure represented by the general formula (1):
—O—R
1
—CH(R
2
)—CH
2
—(Si(R
3
2−b
)(X
b
)O)
m
Si(R
4
3−a
)X
a
(1)
wherein R
1
represents a divalent organic group of 1 to 20 carbon atoms containing at least one constituent element selected from the group consisting of hydrogen, oxygen and nitrogen, R
2
represents an alkyl group of 1 to 10 carbon atoms, R
3
and R
4
may be the same or different and each represents an alkyl group of 1 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms or an aralkyl group of 7 to 20 carbon atoms or a triorganosiloxy group of the formula (R′)
3
SiO—, in which R′ is a monovalent hydrocarbon group of 1 to 20 carbon atoms and the three R′ groups may be the same or different and, where there are two or more R
3
or R
4
groups, they may be the same or different; X represents a hydroxyl group or a hydrolyzable group and, where there are two or more X groups, they may be the same or different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, m represents an integer of 0 to 19, and the b's in the m —(Si(R
3
2−b
) (X
b
)—O)—groups maybe the same or different, provided that the condition a+&Sgr;b≧1 is satisfied.
In a preferred embodiment, this invention is related to the above curable resin composition wherein R
1
in component (I) is CH
2
.
In a further preferred embodiment, this invention is related to the above curable resin composition wherein R
2
in component (I) is CH
3
.
In a further preferred embodiment, this invention is related to the above curable resin composition
wherein component (I) is a reactive silicon group-containing polyether oligomer having a partial structure represented by the formula:
—O—CH
2
—CH(CH
3
)—CH
2
—Si(CH
3
)(OCH
3
)
2
.
In another preferred embodiment, this invention is related to the above curable resin composition
wherein component (I) is a reactive silicon group-containing polyether oligomer obtainable by reacting a polyether oligomer having an unsaturated bond introduced therein of the general formula (2):
—O—R
1
—C(CH
3
)═CH
2
(2)
wherein R
1
is as defined above, with a reactive silicon group-containing compound represented by the general formula (3):
H—(Si(R
3
2−b
)(X
b
)O)
m
Si(R
4
3−a
)X
a
(3)
wherein R
3
, R
4
, a, b, m and X are as defined above, in an oxygen-containing atmosphere in the presence of a catalyst and a sulfur compound.
In a further preferred embodiment, this invention is related to the above curable resin composition
wherein component (I) is a reactive silicon group-containing polyether oligomer having a partial structure represented by the formula:
—O—CH
2
—CH(CH
3
)—CH
2
—Si(CH
3
)(OCH
3
)
2
as obtainable by reacting a polyether oligomer having an unsaturated bond introduced therein of the formula:
—O—CH
2
—CH(CH
3
)═CH
2
with a reactive silicon group-containing compound of the formula:
H—Si(CH
3
)(OCH
3
)
2
in an oxygen-containing atmosphere in the presence of a catalyst and a sulfur compound.
In another preferred embodiment, this invention is related to the above curable resin composition
wherein component (II) is a copolymer comprising a molecular chain substantially composed of (a) acrylic and/or methacrylic ester monomer units having a hydrocarbon group of 1 to 8 carbon atoms and (b) acrylic and/or methacrylic ester monomer units having a hydrocarbon group of 10 or more carbon atoms.
In a further preferred embodiment, this invention is related to the above curable resin composition wherein component (II) is a copolymer having a silicon group crosslinkable under siloxane bond formation.
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention is described in detail. The reactive silicon group-containing polyether oligomer to be used as component (I) according to the present invention may be any polyether-based oligomer comprising a polyether as its main chain and, on a side chain or at a terminal, at least one structure represented by the general formula (1)
—O—R
1
—CH(R
2
)—CH
2
—(Si(R
3
2−b
)(X
b
)O)
m
Si(R
4
3−a
)X
a
(1)
wherein R
1
represents a divalent organic group of
Iwakiri Hiroshi
Kotani Jun
Kusakabe Masato
Dawson Robert
Kaneka Corporation
Peng Kuo-Liang
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