# US 4,395,520 A · Process for curing thermosetting resins using sulfur dioxide containing compounds as latent catalysts

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,395,520 A
- Document ID: US4395520A
- Status: Granted
- Kind: A
- Application number: 06/340,852
- 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/US4395520A

## CPC

- C08K 5/41: Compounds containing sulfur bound to oxygen
- C08K 5/42: Sulfonic acids; Derivatives thereof
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

Latent catalysts comprising certain sulfur dioxide containing compounds such as bubadiene sulfone are used in the cure of thermosetting resins which are 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 sulfur dioxide containing compound as a latent catalyst, said compound being stable at at a temperature less than about 60.degree. C. and dissociable into sulfur dioxide at a temperature greater than about 100.degree. C.

### Claim 2 (depends on 1)

A process as in claim 1 wherein said compound is a sulfone with a double bond in the beta position.

### Claim 3 (depends on 1)

A process as in claim 1 wherein said compound is a diene-sulfur dioxide adduct.

### Claim 4 (depends on 1)

A process as in claim 1 wherein said compound is a sulfone of a .alpha.,.beta.-unsaturated ketone.

### Claim 5 (depends on 1)

A process as in claim 1 wherein said compound is a copolymer of sulfur dioxide and an olefinic monomer.

### Claim 6 (depends on 3)

A process as in claim 3 wherein said adduct is butadiene sulfone.

### Claim 7 (depends on 4)

A process as in claim 4 wherein said sulfone is pulegone sulfone or isopulegone sulfone.

### Claim 8 (depends on 1, 2, 3, 4, 5, 6, 7)

A process as in claim 1, 2, 3, 4, 5, 6 or 7 wherein the thermosetting resin comprises a hemiformal having any one of the following structures: ##STR7## 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 9 (depends on 1, 2, 3, 4, 5, 6, 7)

A process as in claim 1, 2, 3, 4, 5, 6 or 7 wherein the thermosetting resin comprises a phenol-formaldehyde resin having the formula: ##STR8## 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, and 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 group, e is at least 1, and wherein at least 50 mole percent of the ##STR9##

### Claim 10 (depends on 8)

A process as in claim 8, said process being a liquid injection process wherein the thermosetting resin is injected directly into a mold.

### Claim 11 (depends on 9)

A process as in claim 9, said process being a liquid injection process wherein the thermosetting resin is injected directly into a mold.

### Claim 12 (depends on 8)

A process as in claim 8, said process being a sheet moldings compound process.

### Claim 13 (depends on 9)

A process as in claim 9, said process being a sheet moldings compound process.

### Claim 14 (depends on 8)

A process according to claim 8 wherein n is from about 1 to about 5.

### Claim 15 (depends on 8)

A process according to claim 8 wherein n is from about 1.2 to about 2.5.

### Claim 16 (depends on 9)

A process according to claim 9 wherein the mole fraction (d/c+d)is from 0. to 0.8.