# US 5,349,091 A · Process for recycling cured polysulfide sealants

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- Number: US 5,349,091 A
- Document ID: US5349091A
- Status: Granted
- Kind: A
- Application number: 08/053,642
- Filed: 1993-04-27
- Granted: 1994-09-20
- Earliest claimed: 1993-04-27
- Assignees: Morton International, Inc.
- Inventors: Michael J. Hallisy; John R. Gilmore; Steven J. Hobbs; Warren G. Duncan
- Web page: https://patentgrep.com/patent/US5349091A

## CPC

- C08J 11/28: by treatment with organic compounds containing nitrogen, sulfur or phosphorus
- C07C 319/24: by reactions involving the formation of sulfur-to-sulfur bonds
- C08J 11/06: without chemical reactions
- C08J 2381/04: Polysulfides
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

Solid waste materials comprising oxidatively-cured, solid polysulfide sealants containing spent oxidant, fillers, plasticizers, and other formulating aids are reverted to a liquid sealant comprising mercaptan-terminated polysulfides by reducing them with a liquid mercaptan-terminated polysulfide at temperatures ranging from about 50.degree. to about 110.degree. C. Upon the addition of fresh curing agent and recuring, the reclaimed sealant has satisfactory tensile strength and elongation properties.

## Claims

### Claim 1

A method for reclaiming a cured polysulfide sealant comprising mixing the sealant in a non-aqueous system at a temperature of from about 50.degree. C. to about 100.degree. C. with an amount of a mercapto-group terminated liquid polysulfide sufficient to provide from about 1.0% to about 3% by weight of mercapto groups in the reclaimed sealant.

### Claim 2 (depends on 1)

The method of claim 1 wherein the temperature is from about 75.degree. to about 100.degree. C.

### Claim 3 (depends on 1)

The method of claim 1 wherein the liquid polysulfide is an oligomer having a molecular weight of from about 400 to about 4000.

### Claim 4 (depends on 1)

The method of claim 1 wherein the cured sealant comprises a residue of an oxide curing agent.

### Claim 5 (depends on 1)

The method of claim 1 wherein the liquid polysulfide is from about 10 to about 50% of the weight of cured, substantially mercapto group-free polysulfide in the sealant.