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US 4,072,795 AGranted
Thin film electrostatic epoxy powder coating process and the resulting article
AssigneeWestinghouse Electric Corp.
InventorCharles M. Noonan
Life of this patent
Estimating the term…
Abstract
A coating powder is made by preparing a composition of two different diglycidyl ethers of bisphenol A and a curing agent, extruding the composition, cooling it to form a solid, and grinding the solid into a powder. Wire or other articles are coated with the coating powder in an electrostatic fluidized bed or with an electrostatic gun and the powder is cured.
Claims26
A method of coating a metallic object with a coating powder comprising:
- (I) applying a coating powder to said metallic object with an electrostatic means selected from the group consisting of a gun and a fluidized bed, said coating powder being made by
- (A) dry mixing a composition which comprises:
- (1) a first diglycidyl ether of bisphenol A having an E.E.W. of about 400 to about 900 and a melting point of about 70.degree. to about 110.degree. C;
- (2) a second diglycidyl ether of bisphenol A having an E.E.W. of about 750 to about 1400 and a melting point of about 100.degree. to about 130.degree. C, where said second diglycidyl ether is different from said first diglycidyl ether and the weight ratio of said first diglycidyl ether to said second diglycidyl ether is about 1 to 1 to about 12 to 1;
- (3) about 10 to about 60% by weight based on the weight of the total composition of an epoxy ester, the epoxy portion of said ester being derived from a diglycidyl ether of bisphenol A having an E.E.W. of about 400 to about 900 and a melting point of about 70.degree. to about 110.degree. C, and the ester portion being derived from a dibasic acid having the formula HOOC--(CH.sub.2).sub.m -- COOH, where m is about 18 to about 54;
- and
- (4) about 2 to about 8 phr of a curing agent for said diglycidyl ethers;
- (B) extruding said composition;
- (C) cooling said composition to form a solid;
- and
- (D) grinding said composition into a powder having a particle size of about 15 to about 74 microns;
- (II) curing said coating powder at about 125.degree. to about 200.degree. C for about 1 to about 10 minutes.
9 more elements
An article comprising a substrate having thereon a coating comprising a cured film less than 2 mils thick of a coating powder made by
- (A) dry mixing a composition which comprises:
- (1) a first diglycidyl ether of bisphenol A having an E.E.W. of about 400 to about 900 and a melting point of about 70.degree. to about 110.degree. C;
- (2) a second diglycidyl ether of bisphenol A having an E.E.W. of about 750 to about 1400 and a melting point of about 100.degree. to about 130.degree. C, where said second diglycidyl ether is different from said first diglycidyl ether and the weight ratio of said first diglycidyl ether to said second diglycidyl ether is about 1 to 1 to about 12 to 1;
- (3) about 10 to about 60% by weight based on the weight of the total composition of an epoxy ester, the epoxy portion of said ester being derived from a diglycidyl ether of bisphenol A having an E.E.W. of about 400 to about 900 and a melting point of about 70.degree. to about 110.degree. C, and the ester portion being derived from a dibasic acid having the formula HOOC--(CH.sub.2).sub.m -- COOH, where m is about 18 to about 54;
- and
- (4) about 2 to about 8 phr of a curing agent for said diglycidyl ethers;
- (B) extruding said composition;
- (C) cooling said composition to form a solid;
- and
- (D) grinding said composition into a powder having a particle size of about 15 to about 74 microns.
7 more elements
Dependencies are inferred from the claim text.