# US 4,391,971 A · Color improvement and acetaldehyde reduction in high molecular weight polyesters

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- Number: US 4,391,971 A
- Document ID: US4391971A
- Status: Granted
- Kind: A
- Application number: 06/334,769
- Filed: 1981-12-28
- Granted: 1983-07-05
- Earliest claimed: 1981-12-28
- Assignees: The Goodyear Tire & Rubber Company
- Inventors: Freddie L. Massey; Douglas D. Callander
- Web page: https://patentgrep.com/patent/US4391971A

## CPC

- C08G 63/90: Purification; Drying
- B29B 13/00: Conditioning or physical treatment of the material to be shaped (chemical aspects C08J3/00 {; heating, cooling or curing during shaping B29C35/00; thermal after-treatment B29C71/02})
- B29C 48/00: Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor (extrusion blow-moulding B29C49/04)
- B29C 48/08: flexible, e.g. films
- B29C 48/09: Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)

## Abstract

This invention relates to a method of improving the brightness and color of a polyester resin and reducing the acetaldehyde content by passing the resin through molecular sieves at a temperature of from 230.degree. C. to about 300.degree. C.

## Claims

### Claim 1

The method of treating molten polyester resin which comprises heating said resin to a temperature of from 230.degree. C. to about 300.degree. C. and passing said resin through a molecular sieve.

### Claim 2

The method of reducing the level of acetaldehyde from molten polyester resin which comprises passing said resin, at a temperature of from 230.degree. C. to about 300.degree. C., through a molecular sieve for a time sufficient to reduce the level of acetaldehyde in said resin.

### Claim 3

The method of improving the brightness and color in a molten polyester resin which comprises extruding said resin through a filter containing a molecular sieve.

### Claim 4 (depends on 2)

The method of claim 2 in which the said molecular sieve consists of crystalline metal alumina silicate with a three dimensional interconnecting network structure of silica and alumina tetrahedron.

### Claim 5 (depends on 2)

The method of claim 2 in which the said polyester is polyethylene terephthalate.

### Claim 6 (depends on 4)

The method of claim 4 in which the said metal is from the group comprising sodium, calcium, potassium or combinations thereof.

### Claim 7 (depends on 2)

The method of claim 2 in which the said molecular sieve is formed of the 13X type (10 angstroms).

### Claim 8 (depends on 2)

The method of claim 2 in which the said molecular sieve is formed of the 4A type (4 angstroms).

### Claim 9

A filter comprising of a molecular sieve, said filter situated between an extruder outlet and a receiving mold or forming die.