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Foam Plastic with Improved Surface Finish

IP.com Disclosure Number: IPCOM000083236D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Delaney, A: AUTHOR [+2]

Abstract

Plastic articles can be molded by injecting into a mold, a heated plastic that has been mixed with a gas such as nitrogen. The molded article has a low-density cellular interior but the surface is dense and is smooth, except for swirls that are characteristic of this molding process.

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Foam Plastic with Improved Surface Finish

Plastic articles can be molded by injecting into a mold, a heated plastic that has been mixed with a gas such as nitrogen. The molded article has a low- density cellular interior but the surface is dense and is smooth, except for swirls that are characteristic of this molding process.

There are many applications for a foam plastic where this customary surface finish is objectionable, and an additional processing step such as painting is required to provide a suitable finish.

It has been found that a smooth surface is achieved by venting the mold throughout its surface. The mold may be lined with a material, such as rubber, that has pores of a suitable size to receive the gas but not to cause the lining material to adhere to the plastic, or otherwise to affect its surface. A thin layer of the porous material is sufficient to provide a reservoir for the gas, and this layer may be backed up by the usual mold materials having the customary venting arrangements.

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