| 摘要 |
<p>A novel polyhydroxy oligomer crosslinkable with aminoplast resins to form a coating composition adapted for use as an automotive topcoat which upon curing forms a hard, glossy, durable coating with outstanding durability and excellent resistance to solvents and water. The coating composition comprises: (A) a polyhydroxy oligomer having a number average (Mn,) molecular weight of between about 250-2000 and being the reaction produce of: (i) an ester having pendant hydroxyl and carboxyl functionality and being made by reacting (a) a C3-C10 aliphatic branched diol, and (b) an alkyl hexahydrophthalic anhydride, wherein (a) and (b) are combined in the reactant mixture in an amount sufficient to allow reaction in at least about a 1:1 molar ratio; and (ii) a C2-C10 monomer, having reactive functionality capable of esterifying said carboxyl functionality of said ester, said C2-C10 monomer being selected from the group consisting of: (a) a monomer wherein said reactive functionality reacts with said carboxyl functionality to form an hydroxy in addition to an ester linkage; (b) a monomer bearing hydroxyl functionality in addition to said reactive functionality and wherein said reactive functionality does not generate an hydroxy in addition to an ester linkage; and (c) a monomer bearing hydroxyl functionality in addition to said reactive functionality wherein said reactive functionality reacts with said carboxyl functionality to form a hydroxyl in addition to an ester linkage, wherein said ester and said C2-C10 monomer are combined in the reactant mixture in an amount sufficient to allow reaction in about a 1:1 molar ratio; (B) an amine-aldehyde or polyisocyanate crosslinking agent; and (C) 0-50 weight percent based on the total weight of (A), (B) and (C) of hydroxy functional additive having a number average molecular weight (Mn) of between about 150-6000. In addition, the coating composition of this invention may include conventional additives such as catalysts, antioxidants, U.V. absorbers, flow control or wetting agents, antistatic agents, pigments, plasticiers, solvents, etc. The oligomers of this composition are also compatible with non-agueous dispersions (NAD's).</p> |
