# US 4,391,965 A · Curing agents

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- Number: US 4,391,965 A
- Document ID: US4391965A
- Status: Granted
- Kind: A
- Application number: 06/315,264
- Filed: 1981-10-26
- Granted: 1983-07-05
- Earliest claimed: 1980-10-27
- Assignees: Imperial Chemical Industries PLC; Hermann Wiederhold GmbH Corp.
- Inventors: Hans R. Falkenburg; Siegfried Krause; Robert C. McGuiness
- Web page: https://patentgrep.com/patent/US4391965A

## CPC

- C09D 163/00: Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
- C08G 59/42: Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
- C08G 59/4223: {aromatic}
- Y10T 428/31529: Next to metal
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A modified polycarboxylic acid polyanhydride curing agent suitable for curing epoxy resins which is prepared by reacting a polycarboxylic acid anhydride with a monohydroxy compound ROH; and coating compositions, comprising the modified curing agent and a solution of an epoxy resin to be cured, which have improved storage stability.

## Claims

### Claim 1

A coating composition which comprises in admixture
(a) a curing agent which is the reaction product of a polycarboxylic acid polyanhydride with a monohydroxy compound ROH, wherein R is alkyl, substituted alkyl, or aralkyl and
(b) a solution of an epoxy resin which is to be cured.

### Claim 2 (depends on 1)

A coating composition according to claim 1 wherein the acid polyanhydride curing agent is heated with the monohydroxy compound ROH to a temperature greater than 60.degree. C. for such a period of time that at least 50% of the anhydride groups are reacted with ROH.

### Claim 3 (depends on 1)

A coating composition according to claim 1 wherein the temperature is greater than 100.degree. C.

### Claim 4 (depends on 1)

A curing agent according to claim 1 wherein at least 75% of the anhydride groups have been reacted with ROH.

### Claim 5 (depends on 1)

A coating composition according to claim 1 wherein ROH is selected from the group an alkanol, an ether alkanol and a hydroxy ester.

### Claim 6 (depends on 1)

A coating composition according to claim 1 wherein the polyanhydride is an adduct of trimellitic anhydride and a polyhydric alcohol.

### Claim 7 (depends on 6)

A coating composition according to claim 6 wherein the polyanhydride is an adduct of trimellitic anhydride and ethylene glycol.

### Claim 8 (depends on 1)

A coating composition according to claim 1 wherein there is also present a solvent selected from the group ester solvents, ketone solvents and aromatic solvents.

### Claim 9 (depends on 1)

A cured coating on a substrate which is prepared by applying to a substrate a coating composition according to claim 1 and thereafter heating the substrate.