Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2000-04-21
2001-08-07
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S025000, C528S901000, C525S453000
Reexamination Certificate
active
06271333
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a one-part moisture curable composition which exhibits excellent storage stability as well as room temperature-curable good adhesion and excellent sheet property in rubber elasticity and strength.
Organic polymers having a reactive silyl group, namely, modified silicone resins have become a versatile resin for use as a sealant having well balanced properties in coating and sealing applications since such polymers are room temperature-curable and the cured products thereof exhibit rubber elasticity owing to their polyether backbone and the like.
However, modified silicone resin has low strength inherently, therefore, modified silicone resin with excellent strength is desired.
In view of such situation, various curable compositions comprising a curable compound capable of imparting the modified silicone resin with strength have been proposed. Examples of such compound are epoxy compounds and isocyanate compounds.
However, when a one-part composition is produced from a modified silicone resin and an isocyanate compound, the isocyanate compound suffers from curing failure due to the blocking of the isocyanate group by the alcohol generated in the curing of the modified silicone resin. When an amine or the like is used for the curing agent of the isocyanate compound, and the isocyanate compound and the amine are stored as a mixture, the mixture undergoes gelation, curing, and the like during its storage and the mixture was not at all storage stable. Even if a latent curing agent having the amine blocked were used, the mixture still suffered from insufficient storage stability.
SUMMARY OF THE INVENTION
The present invention has been completed in view of the prior art technology as described above, and an object of the present invention is to provide a room temperature-curable one-part moisture curable composition which has excellent storage stability, and which can be cured into a cured product exhibiting excellent adhesion, rubber elasticity, and strength.
In the present invention, such object is realized by using the isocyanate compound of particular structure and the latent curing agent of particular structure in the preparation of the one-part moisture curable composition from an organic polymer having a reactive silyl group, an isocyanate compound, and a latent curing agent. Accordingly, the one-part moisture curable composition of the present invention comprises:
(A) an organic polymer having at least one reactive silyl group in the molecule,
(B) an isocyanate compound having at least one isocyanate (NCO) group bonded to secondary or tertiary carbon in the molecule, and
(C) a latent curing agent.
The latent curing agent (C) is preferably a ketimine having ketimine (C═N) bond derived from a ketone or an aldehyde and an amine, having a structure wherein a branched carbon atom or a ring member carbon atom is bonded to &agr; position of at least one of carbon or nitrogen of the ketimine bond.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is hereinafter described in further detail.
The one-part moisture curable composition of the present invention comprises:
(A) an organic polymer having at least one reactive silyl group in the molecule,
(B) an isocyanate compound having a particular structure as described below, and
(C) a latent curing agent.
First, such components contained in the moisture curable composition of the present invention are described.
(A) Organic polymer having at least one reactive silyl group in the molecule
In the present invention, the organic polymer (A) used is the one containing at least one reactive silyl group in the molecule. The term, reactive silyl group used herein designates silanol group or silicon having a hydrolyzable group bonded thereto, and the reactive silyl group undergoes condensation reaction in the presence of moisture or cross-linking agent, and in optional presence of a catalyst.
Typical hydrolyzable groups bonded to the silicon include halogen atom, alkoxy group, acyloxy group, ketoxime group, alkenyloxy group, and the like. Among these, the most preferred is the alkoxy group.
The backbone preferably comprise a rubber-based organic polymer, and examples of such organic polymer include polyether, polyester, ether-ester block copolymer, olefin, and/or conjugated diene rubber, hydrogenate thereof, polychloroprene and other halogenated rubbers, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer, poly(meth)acrylate, and polysulfide-based polymer.
The polyether as mentioned above is preferably an alkylene oxide polymer containing an —RO— group wherein the divalent organic group R is a hydrocarbon group substantially containing 1 to 20 carbon atoms, and preferably 1 to 8 carbon atoms. R is typically methylene, ethylene, propylene, butylene, or tetramethylene, and most preferably, propylene. R may comprise either one of these or a combination of two or more of these.
The polyester as mentioned above is typically a polyester-based polymer obtained by condensation of a dibasic acid such as adipic acid or maleic anhydride and a glycol, or ring-opening polymerization of a cyclic ester such as a lactone.
The olefin and/or the conjugated diene rubber as mentioned above is typically polyisobutylene, polybutadiene, polyisoprene, isobutylene-isoprene copolymer, isoprene-butadiene copolymer, and a copolymer containing butadiene or isoprene.
Exemplary organic polymers (A) containing the reactive silyl group include those produced by the method proposed in JP-B 45-36319, JP-B 46-12154, JP-B 49-82673, JP-A 50-156599, JP-A 51-73561, JP-A 54-6096, JP-A 55-82123, JP-A 55-123620, JP-A 55-125121, JP-A 55-131022, JP-A 55-135135, JP-A 55-137129, and the like, and those produced by the method proposed in JP-A 3-47825, JP-A 3-72527, JP-A 3-43449, JP-A 3-79627, and the like.
Among those described above, the organic polymer (A) is preferably the one containing a polyether, a polyester, an ether-ester block copolymer, and the like as its backbone, and most preferably, the one containing a polyether backbone as its backbone. The backbone is not limited for its molecular weight. The molecular weight of the polyether, the polyester, or the ether-ester block copolymer is preferably about 300 to about 30000, and more preferably, about 500 to about 15000.
The organic polymer (A) preferably used in the present invention is described in further detail.
The organic polymer (A) containing a polyether for its backbone, and at least one reactive silyl group may be produced, for example, by the addition reaction between a silane compound represented by the following general formula (a) and a polyether containing a group represented by the general formula (b) having ethylenic double bond.
In formula (a), X is hydroxyl group or the hydrolyzable group as described above; R
11
is a monovalent hydrocarbon group containing 1 to 20 carbon atoms or a triorganosiloxy group represented by the formula: (R
12
)
3
SiO—; the two or more R
11
may be either the same or different from each other; and n is an integer of 0 or more. The monovalent hydrocarbon group of R
11
may be selected from an alkyl group such as methyl and ethyl; a cycloalkyl group such as cyclohexyl; an aryl group such as phenyl group; and an aralkyl group such as benzyl group. R
12
may be a hydrocarbon group containing 1 to 20 carbon atoms as described above and when two or more R
12
are present, they may be either the same or different from each other.
Examples of the silane compound represented by the formula (a) include halogenated silanes such as trichlorosilane, methyldichlorosilane, dimethylchlorosilane, trimethylsiloxydichlorosilane, etc; alkoxysilanes such as trimethoxysilane, triethoxysilane, methyldimethoxysilane, phenyldimethoxysilane, 1,3,3,5,5,7,7-heptamethyl-1,1-di-methoxytetrasiloxane, etc.; acyloxysilanes such as methyldiacetoxysilane, trimethylsiloxymethylacetoxysilane, etc.; ketoxymate silanes such as bis(dimethylketoxymate) methylsilane, bis(cyclohexylketoxymate) methylsilane, bis(diethylketoxymate) trimethyls
Arent Fox Kintner & Plotkin & Kahn, PLLC
Dawson Robert
The Yokohama Rubber Co. Ltd.
Zimmer Marc S.
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