Sealerless primers
AssigneePPG Industries, Inc.
InventorMartin J. Simon
Life of this patent
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Abstract
A primer composition comprises an oil-free saturated polyester resin, an aminoplast curing agent for the polyester, and a thermoplastic acrylic polymer. The primer is used as a bond coat to adhere an acrylic polymer dispersion topcoat to a metal base.
Claims8
An article comprising a metal substrate having adhered thereto a hard, crack-resistant coating, said coating comprising a layer of cured primer composition adhering to said metal substrate and a layer of an acrylic polymer superimposed upon and adhering to said cured primer composition, wherein said cured primer composition is a mixture of
- a. a saturated resin which is a saturated polyester having hydroxyl functionality, a saturated polyether having hydroxyl functionality or a saturated polyurethane having hydroxyl functionality, and which has been cured with an aminoplast curing agent produced from the condensation products of amines or amides with an aldehyde, to form a thermoset polymer, and
- b. a thermoplastic acrylic polymer which
- (1) is selected from the group consisting of addition polymers of esters of alpha-beta ethylenically unsaturated acids and interpolymers of esters of alpha-beta ethylenically unsaturated acids with other ethylenically unsaturated compounds,
- (2) is essentially uncured with said aminoplast curing agent, and
- (3) is soluble in solvents in which it was soluble before said primer composition was cured.
A method of coating a metallic substrate comprising:
- a. coating said metallic substrate with a primer composition containing:
- (1) an aminoplast curing agent produced from the condensation products of amines or amides with an aldehyde,
- (2) a saturated resin which is curable with said aminoplast curing agent to form a thermoset polymer and which is a saturated polyester having hydroxyl functionality, a saturated polyether having hydroxyl functionality or a saturated polyurethane having hydroxyl functionality, and
- (3) a thermoplastic acrylic polymer which
- (a) is selected from the group consisting of addition polymers of esters of alpha-beta ethylenically unsaturated acids and interpolymers of esters of alpha-beta ethylenically unsaturated acids with other ethylenically unsaturated compounds,
- (b) is essentially non-curable with said aminoplast curing agent;
- b. curing said primer composition to form a mixture of
- (1) a thermoset polymer of said saturated resin and said aminoplast curing agent, and
- (2) said thermoplastic acrylic polymer which is soluble in solvents in which it was soluble before said curing;
- c. coating said cured primer composition with a non-aqueous dispersion of an acrylic polymer;
- and
- d. drying said non-aqueous dispersion to provide a coating of said acrylic polymer contained therein.
Dependencies are inferred from the claim text.