Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2000-04-26
2002-01-01
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S020000, C528S022000, C528S043000, C525S100000
Reexamination Certificate
active
06335412
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a curable composition comprising a saturated hydrocarbon polymer having a hydroxyl or hydrolyzable group bound to a silicon atom and a silicon-containing group capable of crosslinking via siloxane bonding (hereinafter referred to as “reactive silicon group”).
BACKGROUND ART
A saturated hydrocarbon polymer containing at least one reactive silicon group per molecule is known to have the interesting property that the hydrolysis of the reactive silicon group in the presence of, for example, moisture and subsequent formation of a siloxane bond give a rubber-like cured product. Because its backbone chain is composed of a saturated hydrocarbon which is scarcely susceptible to degradation by heat and light, this polymer is able to give a cured product having excellent heat resistance, wheathering resistance and gas barrier properties. Therefore, the polymer can be used as a sealing material for double glazing or an elastic sealant for architectural use.
For the curing by crosslinking of the polymer containing a reactive silicon group, a silanol condensation catalyst can be used. The use of a silanol condensation catalyst reduces the necessary cure time. Double glazing, in particular, is an article of commerce which calls for an extremely short delivery term and, therefore, the sealant for double glazing is much required to be fast-curing as a quality; hence there is a demand for a potent silanol condensation catalyst.
Japanese Kokai publication Hei-8-41360 discloses a curable composition utilizing a compound of the formula Q
2
Sn(OZ)
2
or [Q
2
Sn(OZ)]
2
O (wherein Q represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms; Z represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms or an organic group internally having a functional group capable of coordinating with Sn) as a silanol condensation catalyst for expediting the cure of a saturated hydrocarbon polymer having a reactive silicon group. In the presence of such a curing catalyst, the curing reaction tends to proceed more rapidly than the reaction using a bivalent tin curing catalyst such as stannous octanoate or a tin carboxylate such as dibutyltin dilaurate. However, a further curtailment of cure time is necessary for a sealing agent for double glazing or other applications which require a very rapid curing.
As the technology utilizing an additive for accelerating the silanol condensation reaction of a reactive silicon group-containing saturated hydrocarbon polymer, Japanese Kokai publication Hei-2-97562 discloses a curable composition utilizing “a polyhydroxymonosilane such that the number of hydroxyl groups bound to silicon atom is not less than 2 per molecule” and Japanese Kokai publication Hei-2-196842 discloses a curable composition utilizing “a silicon compound other than polysiloxane, in which the number of hydroxyl groups bound to a silicon atom is not less than 2 and there are 2 or more silicon atoms per molecule”. Addition of such a silanol compound leads to improved curability but the effect is not satisfactory enough; hence there is a demand for a still more effective additive.
Meanwhile, sealing agents for double glazing are required to have the ability to adhere firmly to various adherends without application of a primer, that is to say the so-called non-primer adhesiveness. Recently, not only in the field of sealing materials for double glazing but also in the field of architectural sealants, the strong non-primer adhesiveness to various adherends is required for the improvement of work efficiency. However, the use of said reactive silicon group-containing saturated hydrocarbon polymer often resulted in an inadequate non-primer adhesion.
SUMMARY OF THE INVENTION
The present invention has for its object to provide a curable composition comprising a reactive silicon group-containing saturated hydrocarbon polymer which features a high curing rate and a high degree of adhesiveness to various adherends.
The inventors of the present invention carried out investigations with due diligence for solving the above-mentioned problems and found that the curing rate and adhesiveness of a composition can be improved without adversely affecting the physical properties of the cured product by adding a determined compound to a reactive silicon group-containing saturated hydrocarbon polymer.
The present invention, therefore, is concerned with a curable composition which comprises
(A) a saturated hydrocarbon polymer having at least one reactive silicon group,
(B) a tetravalent tin compound and
(C) a silicon compound represented by the formula
R
1
a
Si(OR
2
)
4-a
wherein R
1
and R
2
each independently represents a substituted or unsubstituted hydrocarbon group containing 1 to 20 carbon atoms; a represents any of 0, 1, 2 and 3.
The present invention is further concerned with a curable composition improved in both curing rate and adhesiveness, which comprises
(A) a saturated hydrocarbon polymer containing at least one reactive silicon group per molecule and having a molecular weight of 500 to 50,000 and, based on 100 weight parts thereof,
0.1 to 20 weight parts of (B) a tetravalent tin alcoholate and/or
0.02 to 20 weight parts of (C) a silicon compound of the formula
R
1
a
Si(OR
2
)
4-a
wherein R
1
represents an aryl group containing 6 to 20 carbon atoms; R
2
represents a substituted or unsubstituted hydrocarbon group containing 1 to 20 carbon atoms; and a represents any of 0, 1, 2 and 3.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is now described in detail.
The saturated hydrocarbon polymer for use in the present invention is a polymer substantially not containing carbon—carbon unsaturated bond other than an aromatic ring and, as such, includes polyethylene, polypropylene, polyisobutylene, hydrogenated polybutadiene, and hydrogenated polyisoprene, among others.
As the reactive silicon group, there can be mentioned a group of the general formula (2)
(wherein R
3
and R
4
each independently 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— (where R′ groups each independently represents a substituted or unsubstituted hydrocarbon group containing 1 to 20 carbon atoms); X groups each independently represents a hydroxyl group or a hydrolyzable group; b represents any of 0, 1, 2 and 3; c represents any of 0, 1 and 2; provided, however, that both b and c are not simultaneously equal to 0; m represents an integer of 0 or 1 to 19).
As the hydrolyzable group, there can be mentioned the groups in routine use, such as hydrogen, alkoxy, acyloxy, ketoximate, amino, amido, aminooxy, mercapto and alkenyloxy, among others.
Among these, alkoxy, amido and aminooxy are preferred, although alkoxy is particularly preferred in view of its mild hydrolyzability and ease of handling.
The hydrolyzable and/or hydroxyl group may be attached, to 1 to 3 silicon atom(s), and (a+&Sgr;b) is preferably 1 to 5. Where 2 or more hydrolyzable and/or hydroxyl groups bind to the reactive silicon group, they may be the same kind of group or different groups.
The number of silicon atoms forming the reactive silicon group is not less than 1 and where silicon atoms are linked by siloxane bonding or the like, the number of the silicon atoms is preferably not more than 20.
Particularly, the reactive silicon group represented by the general formula (4) is preferred from the standpoint of availability.
(wherein R
4
, X and b are as defined hereinbefore)
The number of reactive silicon groups per molecule of the saturated hydrocarbon polymer is not less than 1, preferably 1.05 to 10, more preferably 1.1 to 5. If the number of reactive silicon groups per molecule is less than 1, curability will be insufficient so that a satisfactory rubber-like elasticity may not be realized.
The reactive silicon group may be located terminally and/or internally within the molecular chain of a satur
Chiba Makoto
Okamoto Toshihiko
Takase Junji
Connolly Bove Lodge & Hutz LLP.
Kaneka Corporation
Yoon Tae H.
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