# US 4,396,734 A · Polymer stabilizers

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- Number: US 4,396,734 A
- Document ID: US4396734A
- Status: Granted
- Kind: A
- Application number: 06/245,851
- Filed: 1981-03-20
- Granted: 1983-08-02
- Earliest claimed: 1981-03-20
- Assignees: GAF Corporation
- Inventors: Earl P. Williams; Donald H. Lorenz
- Web page: https://patentgrep.com/patent/US4396734A

## CPC

- C08K 5/16: Nitrogen-containing compounds {(C08K5/0091 takes precedence)}
- C08K 5/005: {Stabilisers against oxidation, heat, light, ozone}
- Y10S 507/907: Indicating means, e.g. dye, fluorescing agent
- Y10S 507/934: with inhibitor
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Polymer thickeners having a viscosity of at least 10 K, employed in acid media are stabilized with Redox indicators having from 6 to 30 carbon atoms, such as, for example, methylene blue, phenosafranine, pyronine Y, tartrazine, amaranth, methyl orange, an alkali metal salt of diphenylamine sulfonate and malachite green oxalate, which stabilizers are combined with the polymer in a concentration of between about 0.005 to about 1 weight %.

## Claims

### Claim 1

A mucilage composition having a pH less than 7 containing between about 0.5 and about 25 weight % of a vinyl polymer thickener having a K value of between about 10 and about 250 and between about 0.005 and about 1 weight %, based on polymer, of a redox indicator having from 6 to 30 carbon atoms and containing at least one radical selected from the group consisting of amino, cyano and azo, to stabilize said polymer against acidic degradation.

### Claim 2 (depends on 1)

A stabilized mucilage containing the composition of claim 1 and between about 5 and about 25 weight % acid to provide an acidic solution having a pH of from about 0.1 to less than 7.

### Claim 3 (depends on 1)

The composition of claim 1 wherein the redox indicator is present in an amount between about 0.05 and about 0.75 weight %, based on polymer.

### Claim 4 (depends on 1)

The composition of claim 1 wherein the stabilizer for polymers in acidic media is selected from the group consisting of methylene blue; methyl red, orange or green; pyronine Y; phenosafranine; tartrazine; amaranth; malachite green oxalate; basic blue; neutral red and an alkali metal salt of diphenylamine sulfonate.

### Claim 5 (depends on 1)

The composition of claim 1 wherein said polymer is poly-N-vinyl-2-pyrrolidone.

### Claim 6 (depends on 1)

The composition of claim 1 wherein said polymer is a copolymer of vinyl alkyl ether and maleic acid.

### Claim 7 (depends on 1)

The composition of claim 1 wherein said polymer is a copolymer of vinyl alkyl ether and maleic anhydride.

### Claim 8 (depends on 2)

The composition of claim 2 in which said polymer is an interpolymer of methyl vinyl ether and maleic anhydride.

### Claim 9 (depends on 2)

The composition of claim 2 in which said polymer is poly-N-vinyl-2-pyrrolidone cross-linked with diallyl polyethylene glycol.

### Claim 10 (depends on 2)

The composition of claim 2 in which said polymer is a polymer of alkyl vinyl ether wherein said alkyl contains from 1 to 2 carbon atoms.

### Claim 11 (depends on 4)

The composition of claim 4 in which said indicator is methylene blue.

### Claim 12 (depends on 4)

The composition of claim 4 in which said indicator is phenosafranine.

### Claim 13 (depends on 4)

The composition of claim 4 in which said indicator is malachite green.

### Claim 14 (depends on 4)

The composition of claim 4 in which said indicator is amaranth.

### Claim 15 (depends on 4)

The composition of claim 4 in which said indicator is sodium diphenylamine sulfonate.

### Claim 16 (depends on 4)

The composition of claim 4 in which said solution is an aqueous solution containing from 0.5 to 25 percent of a mineral acid.

### Claim 17 (depends on 16)

The composition of claim 16 in which said acid is hydrogen chloride.

### Claim 18 (depends on 16)

The composition of claim 16 in which said acid is phosphoric acid.

### Claim 19 (depends on 2)

The composition of claim 2 comprising between about 0.5 and about 25% by weight of poly-N-vinyl-2-pyrrolidone in an acidic aqueous solution containing between about 0.05 and about 0.75 weight % based on polymer of methylene blue.