Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1982-08-09
1987-12-01
Bleutge, John C.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525162, 525163, 524314, 524361, C08L 3700, C08L 6124, C08L 6128
Patent
active
047105437
DESCRIPTION:
BRIEF SUMMARY
Reference is made to commonly assigned and concurrently filed U.S. applications Ser. Nos. 432,897, now abandoned, entitled "Acrylic-Hydroxy-Epoxy High Solids Coating Compositions" and 432,896 entitled "High Solids Coating Compositions", both to Chattha et al.
TECHNICAL FIELD
This invention relates to high solids, thermosetting coating compositions, which when cured, exhibit excellent weatherability and are adapted to provide an automotive topcoat which demonstrates hardness, high gloss and excellent resistance to solvents and water. More particularly, the coating compositions of this invention comprise a mixture of a low molecular weight glycidyl-functional/hydroxyl-functional acrylic copolymer, dicarboxylic acid anhydride including at least about 50 weight percent of alkyl hexahydrophthatic anhydride, amine-aldehyde crosslinking resins and solvent. The composition mixture reacts in situ during curing at elevated temperature to form the coating.
BACKGROUND OF THE INVENTION
Because of increasingly strict solvent emission regulations in recent years, low solvent emission paints have become very desirable. A number of high solids paint compositions have been proposed to meet these low solvent emission requirements. However, many of the compositions are deficient because of difficulty in application, slow curing rates, complex and/or time consuming composition formulation, poor durability and low solvent and water resistance of the coating.
One composition, which has been proposed to overcome these deficiencies is taught in U.S. application Ser. No. 334,684, filed Dec. 12, 1981, now U.S. Pat. No. 4,394,486, in the name of the inventors of this application. In that composition, hydroxy functional acrylic copolymers react with anhydrides of dicarboxylic acids to produce hydroxy acid and polyacid copolymers. The composition of such a mixture is largely dictated by the stoichiometry of the reactants employed. These acid products are then reacted with epoxies to produce hydroxy functional resins. Subsequently a composition comprising a mixture of these hydroxy functional resins and amine-aldehyde crosslinking agent can be applied to a substrate and cured at elevated temperatures to obtain a crosslinked structure. Unexpectedly, we have now found that all of the aforementioned reactions can be carried out in situ during curing on the substrate to obtain high solids coatings with excellent physical properties. While not wishing to be bound by theory, it is believed that in this reaction sequence the hydroxyl functionality of the glycidyl hydroxy acrylic copolymer reacts with the anhydride to produce acid functionality which further reacts with the epoxide functionality of the copolymer to produce hydroxyl moiety; then at higher temperatures, the amine-aldehyde reacts with the hydroxyl functionality to produce a crosslinked network. This crosslinking reaction is facilitated by the unconsumed acid present in the composition.
DISCLOSURE OF THE INVENTION
The thermosetting coating composition of this invention preferably contains greater than about 60% by weight, more preferably greater than 70% by weight, of nonvolatile solids. The composition is characterized in that it comprises a mixture of: groups, wherein the total of such epoxide and hydroxyl groups per molecule is preferably greater than about three, most preferably about five, and having a number average molecular weight (M.sub.n) of between about 1000 and about 5000, preferably between about 1500 and about 3000; percent, preferably greater than about 80 weight percent, of alkyl hexahydrophthalic anhydride; form the coating.
The acrylic copolymer is prepared from a monomer mixture comprising (i) between about 5 and about 35, preferable between about 10 and about 20 weight percent of glycidyl ester of a monoethylenically unsaturated carboxylic acid, (ii) between about 5 and about 35, preferably between about 10 and about 20 weight percent of hydroxy alkyl acrylate or hydroxy alkyl methacrylate and (iii) between about 60 and about 90 weight percent of other
REFERENCES:
patent: 3622651 (1971-11-01), Vasta
patent: 3932367 (1976-01-01), Labana et al.
patent: 4044070 (1977-08-01), Labana et al.
patent: 4069275 (1978-01-01), Labana et al.
patent: 4178319 (1979-12-01), Chattha
patent: 4178321 (1979-12-01), Chattha
patent: 4181783 (1980-01-01), Chattha
Chattha Mohinder S.
Theodore Ares N.
Bleutge John C.
E. I. Du Pont de Nemours and Company
Fricke Hilmar L.
Sellers II Robert E. L.
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