# US 4,395,521 A · Process for curing thermoset resins using phenyl esters of carboxylic acids as latent catalysts

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- Number: US 4,395,521 A
- Document ID: US4395521A
- Status: Granted
- Kind: A
- Application number: 06/340,854
- Filed: 1982-01-20
- Granted: 1983-07-26
- Earliest claimed: 1982-01-20
- Assignees: Union Carbide Corporation
- Inventors: Sui-Wu Chow; George L. Brode
- Web page: https://patentgrep.com/patent/US4395521A

## CPC

- C08K 5/105: with phenols
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

Latent catalysts comprising the phenyl esters of certain carboxylic acids are disclosed for use in the cure thermosetting resins curable by an acid catalyst.

## Claims

### Claim 1

In a process for the curing of a thermosetting resin which is curable using an acid catalyst, the improvement being the use of a phenyl ester of a carboxylic acid as a latent catalyst, said phenyl ester being hydrolyzable at a temperature greater than 100.degree. C. and in the presence of water to form a carboxylic acid having a pK.sub.a of about 2 or less.

### Claim 2 (depends on 1)

A process as in claim 1 wherein the thermosetting resin comprises a hemiformal having any one of the following structures: ##STR5## wherein R is a monovalent radical selected from the group consisting of alkyl from 1 to 18 carbon atoms, cycloalkyl from 5 to 8 carbon atoms, aryl containing from 1 to 3 aromatic rings, aralkyl, alkaryl, alkoxy containing from 1 to 18 carbon atoms, aroxy containing 1 to 3 aromatic nuclei, a halide radical, alkyl sulphido having from 1 to 18 carbon atoms, aryl sulphido having from 1 to 3 aromatic nuclei, and a radical derived from linseed oil or tung oil, n is a positive number of at least 1, b is 1 to about 5, c is 1 to about 3, and d is 0 to about 2, x is 0 to 3, the sum of c and d is at least 1 and no greater than 3 and the sum of c, d, and x is at least 1 but no greater than 5, where x=0 for at least 50 mole percent of the hemiformal, and with respect to the R substituent, at least 2 of the ortho- and para- positions are free in relation to the --OH and --O(CH.sub.2 O).sub.n H groups.

### Claim 3 (depends on 1)

A process as in claim 1 wherein the thermosetting resin comprises a phenol-formaldehyde resin having the formula: ##STR6## wherein a is from 0 to 3, b is 0 to 1, the sum of a and b does not exceed 3, the sum of c and d is from 2 to about 20, the mole fraction d/(c+d) is 0.4 to 0.9, R is --(CH.sub.2 O(CH.sub.2 O).sub.e H, e is 0 to about 5, and X is a monovalent radical selected from the group consisting of alkyl from 1 to 18 carbon atoms, cycloalkyl from 5 to 8 carbon atoms, aryl containing from 1 to 3 aromatic rings, aralkyl, alkaryl, alkoxy containing from 1 to 18 carbon atoms, aroxy containing 1 to 3 aromatic nuclei, a halide radical, alkyl sulphides having from 1 to 18 carbon atoms, aryl sulphides having from 1 to 3 aromatic nuclei, wherein for at least one of the R or --O(CH.sub.2 O).sub.e H groups, e is at least 1 and wherein at least 50 mole percent of the ##STR7##

### Claim 4 (depends on 1, 2, 3)

A process as in claims 1, 2 or 3 wherein the latent catalyst is an ester of a polymer having acid groups incorporated into its structure.

### Claim 5 (depends on 1, 2, 3)

A process as in claims 1, 2 or 3 wherein the latent catalyst is phenyl hydrogen maleate or phenyl trifluoracetate.

### Claim 6 (depends on 1, 2, 3)

A process as in claim 1, 2 or 3, a said process being a liquid injection process wherein the thermosetting resin is injected directly into a mold.

### Claim 7 (depends on 1, 2, 3)

A process as in claim 1, 2 or 3, a said process being a sheet molding compounds process.

### Claim 8 (depends on 2)

A process according to claim 2 wherein n is from about 1 to about 5.

### Claim 9 (depends on 2)

A process according to claim 2 wherein n is from about 1.2 to about 2.5.

### Claim 10 (depends on 3)

A process according to claim 3 wherein the mole fraction d/c+d is from 0.6 to 0.8.