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
2002-11-12
2004-08-31
Wu, David W. (Department: 1713)
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...
C524S588000, C524S612000, C524S425000, C525S326100, C526S089000, C526S194000
Reexamination Certificate
active
06784240
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a curable composition. More particularly, it relates to a curable composition which comprises a vinyl polymer having at least one crosslinking silyl group, together with heavy or ground calcium carbonate having a specific surface area of not smaller than 1.5 m
2
/g but not larger than 50 m
2
/g.
BACKGROUND ART
Unlike polymers obtained by ionic polymerization or polycondensation, few vinyl polymers obtainable by radical polymerization and having a functional group, in particular a terminal functional group, have been put to practical use. Among vinyl polymers, (meth)acrylic polymers have high weatherability, transparency and other characteristics that cannot be possessed by the polyether polymers, hydrocarbon polymers or polyester polymers. (Meth) acrylic polymers having an alkenyl group or crosslinking silyl group on their side chains are being utilized in high-weatherability coating compositions and the like. On the other hand, the polymerization of acrylic polymers is not easy to control because of side reactions. Moreover, introduction of functional group into terminus is very difficult.
Vinyl polymers having an alkenyl group at a molecular chain terminus, if obtained by a simple and easy method, cured products excellent in cured product physical properties will possibly be obtained as compared with vinyl polymers having crosslinking groups on their side chains. Therefore, investigations concerning the methods of production thereof have been made by a number of researchers. However, it is not easy as yet to produce them on an industrial scale. In Japanese Kokai Publication Hei-01-247403 and Japanese Kokai Publication Hei-05-255415, for instance, there is disclosed a method of synthesizing alkenyl group-terminated (meth) acrylic polymers which uses an alkenyl group-containing disulfide as a chain transfer agent.
In Japanese Kokai Publication Hei-05-262808, there is disclosed a method of synthesizing alkenyl group-terminated (meth)acrylic polymers which comprises synthesizing a vinyl polymer having a hydroxyl group at both termini using a hydroxyl group-containing disulfide and further utilizing the reactivity of the hydroxyl group.
In Japanese Kokai Publication Hei-05-211922, there is disclosed a method of synthesizing silyl group-terminated (meth)acrylic polymers which comprises synthesizing a vinyl polymer having a hydroxyl group at both termini using a hydroxyl group-containing polysulfide and further utilizing the reactivity of the hydroxyl group.
By any of these methods, however, it is difficult to introduce functional groups into both termini of the molecule with certainty so that a cured product having satisfactory characteristics may hardly be obtained. For introducing functional groups into both termini of the molecule with certainty, it is essential to use a large amount of the chain transfer agent, and this is a problem from the production process viewpoint. In carrying out these methods, ordinary radical polymerization is used, so that it is difficult to control the molecular weight and molecular weight distribution (ratio between weight average molecular weight and number average molecular weight) of the polymer to be obtained.
In view of such state of the art, the present inventors have so far made a large number of inventions relating to various crosslinking functional group-terminated vinyl polymers, methods of producing the same, curable compositions comprising the same and uses thereof (see, for example, Japanese Kokai Publication Hei-11-080249, Japanese Kokai Publication Hei-11-080250, Japanese Kokai Publication Hei-11-005815, Japanese Kokai Publication Hei-11-116617, Japanese Kokai Publication Hei-11-116606, Japanese Kokai Publication Hei-11-080571, Japanese Kokai Publication Hei-11-080570, Japanese Kokai Publication Hei-11-130931, Japanese Kokai Publication Hei-11-100433, Japanese Kokai Publication Hei-11-116763, Japanese Kokai Publication Hei-09-272714 and Japanese Kokai Publication Hei-09-272715).
For example, a vinyl polymer having a silicon-containing group (hereinafter also referred to as “crosslinking silyl group”), which has a silicon atom-bound hydroxyl group or a hydrolyzable group and is capable of being crosslinked under formation of a siloxane bond, or cured products derived from a composition comprising such vinyl polymer are excellent in heat resistance and weatherability and are applicable in various uses, including, but being not limited to, sealants such as elastic sealants for building and construction and sealants for multilayer glass, materials for electric and electronic parts, such as solar battery backside sealants, electric insulating materials such as insulating sheath for electric wires and cables, pressure sensitive adhesives, adhesives, elastic adhesives, paints, powder coatings, coating materials, foamed articles, potting agents for electric and electronic use, films, gaskets, casting materials, various molding materials, and rustproof and waterproof sealants for end faces (cut edges)of net glass or laminated glass.
Among them, elastic sealants for building and construction contain in many cases general-purpose heavy or ground calcium carbonate having a specific surface area of about 1 m
2
/g as incorporated therein. This is for the purpose of reducing the cost of compositions and improving the restorability of cured products, among others. However, when such general-purpose heavy or ground calcium carbonate is used in the above-mentioned vinyl polymers having a crosslinking functional group, there arises a problem in that cured products showing a high level of elongation as required of elastic sealants for building and construction can hardly be obtained. Furthermore, the curable composition tends to readily string, hence improvements in viscosity ratio and knife releasability are required in certain instances.
On the other hand, as a demand from the relevant market, not only sealants for multilayer glass but also elastic sealants for building and construction (in particular single-component elastic sealants) are required to be capable of firmly bonding to various adherends without applying any primer, namely to be excellent in non-primer adhesiveness. Furthermore, sealing compositions for use in contact with glass, for example sealants for multilayer glass, are required to be excellent in weather-resistant adhesiveness, in particular. However, when the above-mentioned general-purpose heavy or ground calcium carbonate is used in combination with the above-mentioned crosslinking functional group-containing vinyl polymers, the non-primer adhesiveness and weather-resistant adhesiveness are unsatisfactory. A particular problem is that the weather-resistant adhesiveness to highly insulating, heat ray-reflecting glass whose surface is coated with a metal oxide or the like is insufficient.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to improve the viscosity ratio and knife releasability of a curable composition whose main component is a vinyl polymer having at least one crosslinking functional group and improve the cured products obtained therefrom with respect to their breaking strength, breaking elongation, adhesiveness to various adherends, and weather-resistant adhesiveness to various kinds of glass, in particular heat ray-reflecting glass.
In view of the state of the art as explained above, the present inventors made intensive investigations and, as a result, found that when a specific filler is added to the above polymer, the viscosity ratio and knife releasability of the resulting composition can be improved without lowering the rate of curing of the composition or without otherwise adversely affecting the same and, at the same time, the breaking strength, breaking elongation, adhesiveness and weather-resistant adhesiveness of the cured products to various adherends derived therefrom can be improved. The inventors have thus solved the above-discussed problems and have been led to completion of the present invention.
The invention thus
Hasegawa Nobuhiro
Nakagawa Yoshiki
Shimizu Yasuo
Kaneka Corporation
Sastri Satya
Westerman Hattori Daniels & Adrian LLP
Wu David W.
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