Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1998-12-23
2001-10-09
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S487000, C524S488000, C524S489000, C524S491000
Reexamination Certificate
active
06300404
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a curable polymer composition which is curable in the presence of moisture and has improved surface tack (stickiness).
PRIOR ART
Polymers having a silicon-containing group, which has a hydroxyl or hydrolyzable group bonded to the silicon atom and can be crosslinked through a silanol condensation reaction (hereinafter referred to as “reactive silicon-containing group”), are crosslinked and cured in the presence of moisture. Curable compositions comprising polymers having backbones of oxyalkylene polymers such as polyoxypropylene and the reactive silicon-containing group among the above polymers are widely used, for example, as sealants for construction, since they are in the liquid state at room temperature, and are cured to provide rubbery elastic materials. However, tack (stickiness) remains on the surfaces of the cured materials of such compositions according to the compositions of the curable compositions or curing conditions, and dirts or dusts adhere to the surfaces, which deteriorate the appearance of the cured materials.
To overcome such defects, for example, JP-A-55-21453 discloses the addition of organic silicone polymers to the polymers having the reactive silicon-containing group. The addition of the organic silicone polymer deteriorate mechanical properties such as modulus, strength at break, elongation, and the like, although the tack is improved.
JP-A-55-36241 discloses the addition of photocurable materials, JP-A-1-149851 discloses the addition of liquid diene polymers, and JP-A-1-188557 discloses the addition of silicone compounds having long chain hydrocarbon groups, to the polymers having the reactive silicon-containing group. However, the addition of such materials increases the cost of the curable compositions, and also has drawbacks that the tack is insufficient in a relatively early stage of curing, and satisfactory effects are not obtained with some compositions or under some curing conditions.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a curable composition comprising a polymer having a reactive silicon-containing group, which is less expansive and can decrease the tack of a cured product without deteriorating modulus and elongation at break of the cured material.
Accordingly, the present invention provides a curable polymer composition comprising
(a) an oxyalkylene polymer having a silicon-containing group which has a hydroxyl or hydrolyzable group bonded to the silicon atom and can be crosslinked through a silanol condensation reaction, and
(b) a paraffinic hydrocarbon.
The curable polymer composition of the present invention may additionally contain.
(c) a silicone compound having a long chain hydrocarbon group, which is preferably a silicone compound having a C
8-20
alkyl group.
DETAILED DESCRIPTION OF THE INVENTION
The backbone of the oxyalkylene polymer having the reactive silicon-containing group (a) which is contained in the composition of the present invention comprises a repeating unit of the formula (1):
—R
1
—O— (1)
wherein R
1
is a divalent organic group, preferably a straight or branched alkylene group having 1 to 14 carbon atoms.
Examples of the repeating unit of the formula (1) are —CH
2
O—, —CH
2
CH
2
O—, —CH
2
CH(CH
3
)O—, —CH
2
CH(C
2
H
5
)O—, —CH
2
C(CH
3
)
2
O—, —CH
2
CH
2
CH
2
CH
2
O—, and the like.
The backbone of the oxyalkylene polymer may consist of the single kind of the repeating unit, while it may comprise two or more kinds of repeating units in which the R
1
groups are different. In particular, polymers comprising propylene oxide, particularly polyoxypropylene are preferable, when the compositions are used as sealants, and the like.
The reactive silicon-containing group included in the polymer (a) of the composition according to the present invention is preferably a group of the formula (2):
wherein R
2
and R
3
are the same or different and represent a C
1-20
alkyl group, a C
6-20
aryl group, a C
7-20
aralkyl group or a triorganosiloxy group of the formula: (R
4
)
3
SiO— in which three R
4
groups are the same or different and represent a C
1-20
alkyl group, provide that when two or more R
2
or R
3
groups are present, they may be the same or different; the X groups are the same or different and represent a hydroxyl group or a hydrolyzable group; a is 0, 1 or 2; and b is 0, 1, 2 or 3, provided that the sum of a and b is not 0; and n is an integer of 0 to 19, with the proviso that the suffixes “a” in the repeating units:
may be the same or different.
The hydrolyzable group X in the formula (2) may not be limited, and may be any conventional hydrolyzable group. Examples of such a group are a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoxymate group, an amino group, an amido group, an acid amide group, an aminoxy group, a mercapto group, an alkenyloxy group, and the like. Among them, a hydrogen atom, alkoxy, acyloxy, ketoximate, amino, amido, aminoxy, mercapto and alkenyloxy groups are preferable. In particular, the alkoxy group is preferable in view of its mild hydrolyzability and easy handling.
One, two or three hydrolyzable groups and/or hydroxyl groups can be attached to one silicon atom, and the total number of the hydrolyzable groups and/or hydroxyl groups, that is, (na+b) is preferably between 1 and 5. When two or more hydrolyzable or hydroxyl groups are present in the reactive silicon-containing group, they may be the same or different.
The reactive silicon-containing group contains at least one silicon atom. When the silicon atoms are bonded through siloxane bonds or the like, the number of silicon atoms is preferably about 20.
Among the reactive silicon-containing groups, a reactive silicon-containing group of the formula (4):
wherein R
3
, X and b are the same as defined above, because of easy availability.
Specific examples of the R
2
and R
3
groups are alkyl groups (e.g. a methyl group, an ethyl group, etc.), cycloalkyl groups (e.g. a cyclohexyl group, etc.), aryl groups (e.g. a phenyl group, etc.), aralkyl groups (e.g. a benzyl group, etc.), triorganosiloxy groups of the formula (R
4
)
3
SiO— in which R
4
is a methyl group or a phenyl group. In particular, a methyl group is preferable as the R
2
and R
3
groups.
The particularly preferable reactive silicon-containing group is —Si(CH
3
)—(OCH
3
)
2
.
The reactive silicon-containing group may be introduced in the polymers by any known methods. The following methods are exemplified:
(i) An oxyalkylene polymer having a functional group such as a hydroxyl group in a molecule is reacted with an organic compound having an unsaturated group and an active group which is reactive with the functional group in the oxyalkylene polymer, to obtain the oxyalkylene polymer having unsaturated groups. Alternatively, an epoxy compound having an unsaturated group and an alkylene oxide are copolymerized to obtain an oxyalkylene polymer having an unsaturated groups. Then, the reaction product is reacted with a hydrosilane having a reactive silicon-containing group for the hydrosilylation of the reaction product.
(ii) The oxyalkylene polymer having the unsaturated groups, which has been obtained in the same manner as in the method (i), is reacted with a compound having a mercapto group and a reactive silicon-containing group.
(iii) An oxyalkylene polymer having a functional group such as a hydroxyl group, an epoxy group, an isocyanate group, etc. is reacted with a compound having a reactive silicon-containing group and a functional group reactive with the above functional group.
Among these methods, the method (i) and the method (iii) in which a polymer having a hydroxyl group at a chain end and a compound having an isocyanate group and a reactive silicon-containing group are reacted, are preferable.
The oxyalkylene polymer as the component (a) used according to the present invention may be a linear or branched one, and its molecular weight is preferably between about 500 and about 50,000, preferably between 1000 and 20,000.
The number of t
Azuma Masaaki
Hashimoto Kazumasa
Kawakubo Fumio
Nishimura Keiko
Foley & Lardner
Kanegafuchi Chemical Industry Co. Ltd.
Rajguru U. K.
Seidleck James J.
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