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Treatment for Removal of Mold Release Agent From Reaction Injection Molding Plastics

IP.com Disclosure Number: IPCOM000020296D
Publication Date: 2003-Nov-11
Document File: 2 page(s) / 57K

Publishing Venue

The IP.com Prior Art Database

Abstract

A combination of a phosphoric acid based cleaner with a modified lignosulfonate such as modified sodium lignosulfonate has been found to provide improved cleaning of mold release agents such as zinc stearate from Reaction Injection Molding plastic parts.

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Treatment for Removal of Mold Release Agent From

Reaction Injection Molding Plastics

Abstract

A combination of a phosphoric acid based cleaner with a modified lignosulfonate such as modified sodium lignosulfonate has been found to provide improved cleaning of mold release agents such as zinc stearate from Reaction Injection Molding plastic parts.

Disclosure

Reaction Injection Molding (RIM) is the process used to make polyurethane parts. RIM parts are made by reacting a polyol with an isocyanate containing material to form a polyurethane. Because of polyurethane’s inherent stickiness, an internal mold release agent, typically zinc stearate, is generally formulated into the mixture so the parts can be easily removed form the molds.

The internal mold release agents in RIM parts makes it more difficult to clean the most other types of plastics. The challenge with RIM internal mold release is that it is not bound in the plastic polymer matrix and is mobile. Because of this, the mold release material can be found both on the surface of the part and also dispersed throughout the finished part. The presence of mold release agent on the surface of the part can cause primer to de-wet, or have poor paint adhesion. Thus, it is imperative that the mold release agent be completely removed from the RIM plastic surface and just below the surface as well.

Acid cleaners are used to clean most RIM parts. The most widely used chemistry is to use phosphoric or citric acid based cleaners fed in addition to either ammonium fluoride or gluconic acid. Though...