High temperature adhesive for polymide films
First Claim
1. A method of bonding a metal to a substrate which comprises placing therebetween a prepreg composed of a fibrous substrate coated and impregnated with a tacky polyimide precursor of (a) a substantially equimolar mixture of (i) 2,2-bis[4-(4-(4aminophenoxy)phenyl]hexafluoropropane or 2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane, or both, and (ii) lower alkyl diester of benzophenone tetracarboxylic acid;
- (b) about 2 to 50 weight percent of polyamic acid polyamide producible from components (i) and (ii); and
(c) about 10 to 50 weight percent of solvent;
applying heat to cause the formation of the polyimide in situ while maintaining the metal and first-named substrate in intimate contact with the curing prepreg; and
then cooling the resultant article.
1 Assignment
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Accused Products
Abstract
Thermoplastic polyimides of benzophenone tetracarboxylic acid or an ester or anhydride thereof and a 2,2-bis[4-(amino-phenoxy)phenyl]hexafluoropropane are excellent adhesives for bonding polyimide films to various substrates including polyimide film, metals, etc. The film and substrate need not be abraded before application of the polyamic acid resin or polyimide precursor from which the polyimide is formed on curing. The bond is tenacious. Even after heating to 800° F. the bond was stronger than two different polyimide films. Interposing between the polyimide film and the substrate a strip or patch of a prepreg made from polyimide precursor solutions composed of monomers, solvent and polyamide acid, and applying heat to cure the resin in situ while keeping the components in intimate contact by application of slight pressure is a preferred way of applying and utilizing the adhesives. Such prepregs are also useful for bonding metal to metal or to various other substrates.
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Citations
24 Claims
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1. A method of bonding a metal to a substrate which comprises placing therebetween a prepreg composed of a fibrous substrate coated and impregnated with a tacky polyimide precursor of (a) a substantially equimolar mixture of (i) 2,2-bis[4-(4-(4aminophenoxy)phenyl]hexafluoropropane or 2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane, or both, and (ii) lower alkyl diester of benzophenone tetracarboxylic acid;
- (b) about 2 to 50 weight percent of polyamic acid polyamide producible from components (i) and (ii); and
(c) about 10 to 50 weight percent of solvent;
applying heat to cause the formation of the polyimide in situ while maintaining the metal and first-named substrate in intimate contact with the curing prepreg; and
then cooling the resultant article. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- (b) about 2 to 50 weight percent of polyamic acid polyamide producible from components (i) and (ii); and
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14. A method of bonding a polyimide film to a substrate which comprises placing therebetween a prepreg composed of a fibrous substrate coated and impregnated with a tacky polyimide precursor of (a) a substantially equimolar mixture of (i) 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane or 2,2-bis[4(3-aminophenoxy)phenyl]hexafluoropropane, or both, and (ii) lower alkyl diester of benzophenone tetracarboxylic acid;
- (b) about 2 to 50 weight percent of polyamic acid polyamide producible from components (i) and (ii); and
(c) about 1 to 50 weight percent of solvent;
applying heat to cause the formation of the polyimide in situ while maintaining the polyimide film and first-named substrate in intimate contact with the curing prepreg; and
then cooling the resultant article. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
- (b) about 2 to 50 weight percent of polyamic acid polyamide producible from components (i) and (ii); and
Specification