Description curable composition

Details Description curable composition Description curable composition

2000-03-29

2002-08-20

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From silicon reactant having at least one...

C528S015000, C528S023000, C528S031000, C528S038000, C524S742000, C525S404000

Reexamination Certificate

active

06437072

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a curable composition having good storage stability, which comprises a reactive silicon group-containing polyether oligomer and a hydrolyzable silicon compound having a hydrolyzable group bound to a silicon atom, said hydrolyzable group being more reactive with H
2
O than the silicon group in the reactive silicon group-containing polyether oligomer and/or an amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound.
PRIOR ART
Room temperature curing compositions comprising a reactive silicon group-containing polyether oligomer, one or more of various additives and a silanol condensation catalyst are known in the art and are used as sealants, adhesives and so on.
It is known that when, in using the above oligomer in an one-component type curable composition, a hydrolyzable silicon compound having a hydrolyzable group bound to a silicon atom, said hydrolyzable group being more reactive with H
2
O than the silicon group in said oligomer, dehydration is effected in the system, so that storage stability can be secured (Japanese Kokai Publication Hei-05-287188).
However, this dehydration technique, which is based on the difference in reactivity with H
2
O, allows the storage stability to decrease when the difference between the rate of reaction in the reaction of the silicon group of the reactive silicon group-containing polyether oligomer with H
2
O and the rate of reaction in the reaction of the dehydrating agent with H
2
O is small. Further, with the increase in H
2
O content, the decrease in storage stability becomes more remarkable.
On the other hand, it is also known that curable compositions comprising a reactive silicon group-containing polyether oligomer, when supplemented with an amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound, acquires good adhesiveness to various adherents (Japanese Kokai Publication Hei-05-70759).
However, when such amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound is admixed with the reactive silicon group-containing polyether oligomer in the presence of water, the amino group functions as a curing catalyst and the condensation reaction proceeds between the silicon groups in the reactive silicon group-containing polyether oligomer, resulting in worsening of the storage stability. Therefore, it is necessary to use the amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound, which is a tackifier, by adding it to one-component type curable compositions which can be tightly sealed in a low water content condition or by admixing it with the reactive silicon group-containing polyether oligomer just prior to use.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a curable composition having good storage stability even when it contains a hydrolyzable silicon compound and/or an amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound, by reducing the reactivity of the silicon group of the reactive silicon group-containing polyether oligomer through introduction of a methyl group into said oligomer in the vicinity of said silicon group. Another object of the invention is to provide a curable composition having better storage stability as compared with the prior art in the case of a hydrolyzable silicon compound being added as a dehydrating agent, by widening the difference in rate of reaction with H
2
O between the dehydrating agent and the above-mentioned oligomer. A further object of the invention is to provide a curable composition with an advantageously enlarged range of dehydrating agents usable therein by reducing the reactivity of the silicon group of said oligomer to thereby make it possible to use those hydrolyzable silicon compounds which can never been used in the prior art.
A still further object of the invention is to provide a novel curable composition showing good storage stability even in the presence of water, in case of adding an amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound, reducing the reactivity of the silicon group of the reactive silicon group-containing polyether oligomer through introduction of a methyl group into said oligomer in the vicinity of said silicon group.
Thus, in accordance with a first aspect of the present invention, there is provided a curable composition which comprises
(A) a reactive silicon group-containing polyether oligomer and
at least one species selected from the following (B) and (C):
(B) a hydrolyzable silicon compound having a hydrolyzable group bound to a silicon atom, said hydrolyzable group being more reactive with H
2
O than the silicon group in the above reactive silicon group-containing polyether oligomer and
(C) an amino group-containing alkoxysilane or amino-substituted alkoxysilane derivative compound, said (A) reactive silicon group-containing polyether oligomer having a partial structure of the general formula (1) per molecule:
13
O—R
1
—CH(CH
3
)—CH
2
—(Si(R
2
2−b
)(X
b
)O)
m
Si(R
3
3−a
)X
a
  (1)
wherein R
1
represents a divalent organic group containing 1 to 20 carbon atoms and one or more constituent atoms selected from the group consisting of hydrogen, oxygen and nitrogen; R
2
and R
3
may be the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms or a triorganosiloxy group of the formula (R′)
3
SiO—; when 2 or more R
2
or R
3
groups are present, they may be the same or different; R′ represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms and three R′ groups may be the same or different; X represents a hydroxyl group or a hydrolyzable group and when two or more X groups are present, they may be the same or different; a represents 0, 1, 2 or 3; b represents 0, 1 or 2; b may be the same or different over m repeats of (Si(R
2
2−b
)(X
b
)O); m represents an integer of 0 to 19; provided that the relation of a+&Sgr;b≧1 is satisfied.
A preferred mode of embodiment is concerned with said curable composition wherein R
1
in said (A) represents CH
2
.
A more preferred mode of embodiment is concerned with the above curable composition
wherein said (A) reactive silicon group-containing polyether oligomer has a partial structure of the following formula:
—O—CH
2
—CH(CH
3
)—CH
2
—Si(CH
3
)(OCH
3
)
2
.
Another preferred mode of embodiment is concerned with the curable composition
wherein said (A) reactive silicon group-containing polyether oligomer is obtainable by reacting a polyether oligomer containing an unsaturated bond of the following general formula (2):
—O—R
1
—C(CH
3
)═CH
2
  (2)
R
1
is as defined above,
with a reactive silicon group-containing compound of the following general formula (3):
H—(Si(R
2
2−b
)(X
b
)O)
m
Si(R
3
3−a
)X
a
  (3)
R
2
, R
3
, a, b, m and X are as defined above,
in the presence of a catalyst and a sulfur compound in an oxygen-containing atmosphere.
Another more preferred mode of embodiment is concerned with the curable composition
wherein said (A) reactive silicon group-containing polyether oligomer has a partial structure of the following formula:
—O—CH
2
—CH(CH
3
)—CH
2
—Si(CH
3
)(OCH
3
)
2
said (A) being obtainable by reacting a polyether oligomer containing an unsaturated bond of the following formula:
—O—CH
2
—C(CH
3
)═CH
2
with a reactive silicon group-containing compound represented by the following formula:
H—Si(CH
3
)(OCH
3
)
2
in the presence of a catalyst and a sulfur compound in an oxygen-containing atmosphere.
Another more preferred mode of embodiment is concerned with the curable composition
wherein, in said (A) reactive silicon-containing polyether oligomer, the number of reactive silicon group is not less than 85% of the number of molecular chain terminals.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is n

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