Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1996-12-13
1998-10-13
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
524284, 524356, 524366, 524379, 524588, 525104, 525437, 525438, 525487, 528 40, 526279, C08G 7700
Patent
active
058213147
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to novel thermosetting compositions and methods of forming a finish coat using said thermosetting compositions.
BACKGROUND ART
Known curing catalysts for epoxy resins include Lewis acid (e.g. aluminum chloride, tin chloride, boron fluoride, boron fluoride ether complex, etc.), metal alcoholate (e.g. aluminum trialkoxide, titanium tetraalkoxide, etc.), aluminum chelate (e.g. trisacetylacetonatoaluminum, etc.), a reaction product of aluminum chelate and active hydrogen compound (reaction product of trisacetylacetonatoaluminum with silanol compound) and the like.
However, a curable composition containing the Lewis acid or metal alcoholate as the catalyst has drawbacks of being pronouncedly low in storage stability at room temperature, and a curable composition containing the aluminum chelate or the reaction product thereof as the catalyst has drawbacks of being low in storage stability at room temperature and giving a cured product which yellows.
Consequently there exists a need for curable compositions which are free from these drawbacks and which are excellent in storage stability, low temperature curability, resistance to discoloration and so on.
In recent years, the environment has been attacked by air pollution, and acid rain has inflicted damages such as withering of woods, thereby posing a serious social problem. Another problem is that coating films on articles for outdoor use such as automotive exterior panels suffer etching, blushing, staining, etc. Accordingly, there is a great need for highly acid resistant coating films.
Finish coats such as those formed on automotive exterior panels readily become marred on collision with, e.g. sand or dust during travel or on friction with washer brushes. Such mar is one of the factors which impair the appearance of the coating film. Especially scratches are likely to stand out in coating films of dark colors, e.g. black, dark blue or brown. Therefore, there is a marked need for the improvement of scratch resistance in finish coats.
At present, there are widely carried out methods of forming a finish coat using an amino-curable coating composition comprising a hydroxyl group-containing resin and an amino resin as a binder. Yet, finish coats which are satisfactory in both of acid resistance and scratch resistance are still unavailable.
Methods of forming a finish coat using other compositions than said amino-curable coating compositions, e.g. coating compositions comprising an epoxy group- and a hydroxyl group-containing resin and a cyclic anhydride such as methylhexahydrophthalic anhydride as a curing agent are disclosed in Japanese Unexamined Patent Publications No. 84673/1988 and No. 84674/1988. However, the disclosed methods are defective in forming finish coats which are inferior in finished appearance, acid resistance, scratch resistance, etc.
An object of the present invention is to provide a curable composition which is excellent in storage stability, curable at low temperatures and capable of forming a cured product free of discoloration.
Another object of the invention is to provide a method of forming a finish coat, the method having overcome the drawbacks of said conventional methods of forming a finish coat and the method being capable of forming a finish coat which is excellent in low temperature curability, finished appearance, acid resistance, scratch resistance, weather resistance, etc.
DISCLOSURE OF THE INVENTION
The present inventors conducted extensive research to achieve said objects and found the following. When a curable composition contains an organotin catalyst as a reaction catalyst in addition to the components for a composition containing epoxy groups and reactive silicon groups as essential functional group components or for a composition containing epoxy groups, reactive silicon groups, and hydroxyl groups and/or carboxyl groups as essential functional group components, the resulting curable composition is outstanding in storage stability, low temperature curability and res
REFERENCES:
patent: 5166265 (1992-11-01), Nakahata et al.
patent: 5175057 (1992-12-01), Wengrovius et al.
patent: 5213899 (1993-05-01), Lucas
Ikushima Satoshi
Isozaki Osamu
Okumura Yasumasa
Tsunoda Minoru
Kansai Paint Company Limited
Marquis Melvyn I.
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