# US 5,922,834 A · Method for treating paint sludge

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- Number: US 5,922,834 A
- Document ID: US5922834A
- Status: Granted
- Kind: A
- Application number: 08/892,486
- Filed: 1997-07-14
- Granted: 1999-07-13
- Earliest claimed: 1995-11-13
- Assignees: Aster Co., Ltd.
- Inventors: Michael Joseph Gerace; Sevilla C. Gamboa; Yasminka S. Landaburu
- Web page: https://patentgrep.com/patent/US5922834A

## CPC

- C08J 11/00: Recovery or working-up of waste materials (recovery of plastics B29B17/00; polymerisation processes involving purification or recycling of waste polymers or their depolymerisation products C08B, C08C, C08F, C08G, C08H)
- 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)

## Abstract

A method of treating paint sludge containing uncured polymer resin, water and/or solvent is provided in which a paint sludge putty is formed which may be used as a replacement for polymeric components used to form compounded polymeric compositions. The treated paint sludge putty or powder comprises from about 5 to 90% by weight of the total compounded polymeric composition and may be used in a variety of compositions including pressure sensitive sealants, caulking sealants, automotive sealants, polyvinyl chloride plastics, rubbers and asphalt cement coatings, and waterbased sealers and coatings.

## Claims

### Claim 1

A method for treating raw paint sludge containing uncured polymer resin, water and/or organic solvent comprising the steps of:
removing a substantial portion of said water and/or organic solvent by drying said paint sludge without curing said polymer resin; and
decatalyzing said paint sludge by treatment with a decatalyzing agent comprising a base having at pH in the range of from 8-13.

### Claim 2 (depends on 1)

The method of claim 1 wherein said raw paint sludge is an organic solvent based paint sludge, a water based paint sludge, a combination water and organic solvent based paint sludge, a reactive curing paint sludge, a powdered coating paint sludge, or combinations thereof.

### Claim 3 (depends on 2)

The method of claim 2 wherein said sludge comprises purged solvent sludge.

### Claim 4 (depends on 2)

The method of claim 2 wherein said sludge comprises still bottoms sludge.

### Claim 5 (depends on 1)

The method of claim 1 wherein the step of drying said paint sludge comprises agitating said sludge under a vacuum at a temperature of about 225.degree. F.

### Claim 6 (depends on 1)

The method of claim 1 wherein said base comprises from about 0.1 to 10% by weight of the raw paint sludge.

### Claim 7 (depends on 1)

The method of claim 1 wherein said base is selected from the group consisting of diethanolamine, 2-amino-2-methyl-2-propanol, diisopropanol amine, triisopropanol amine, potassium hydroxide, and sodium hydroxide.

### Claim 8 (depends on 1)

The method of claim 1 wherein said decatalyzing step takes place prior to said removing step.

### Claim 9 (depends on 8)

The method of claim 8 wherein after the decatalyzing step and prior to the removing step, processing fillers are added at the rate of 5 to 75 weight percent of the raw paint sludge.

### Claim 10 (depends on 9)

The method of claim 9 wherein said processing fillers are selected from the group consisting of carbon black, clay, calcium oxide, calcium sulfate, calcium chloride, magnesium sulfate, sodium sulfate, potassium carbonate, calcium carbonate, silica, talc, hydrated aluminum, wood flour, shells, poly soy, cork and mixtures thereof.

### Claim 11 (depends on 10)

The method of claim 10 wherein said processing fillers are selected from the group consisting of carbon black, clay and mixtures thereof.

### Claim 12 (depends on 1)

The method of claim 1 wherein said removing step is performed without curing said polymer in said paint sludge, and said decatalyzing step is performed thereafter.

### Claim 13

A method for treating raw paint sludge containing water and/or organic solvent and uncured polymer to form a paint sludge putty comprising the steps of:
adding a decatalyzing agent comprising potassium hydroxide to said sludge; and
heating said sludge at a temperature of about 225.degree. F.

### Claim 14 (depends on 13)

The method of claim 13 further including the step of adding 5 to 75% of a processing filler selected from the group consisting of carbon black, clay and mixtures thereof, prior to heating, and wherein a paint sludge powder is formed.