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Coating Nodule Free Coatings on Wire

IP.com Disclosure Number: IPCOM000080928D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Armstrong, EJ: AUTHOR [+2]

Abstract

The application of a TEFLON* coating to small diameter wire in a vertical coater presents a control problem, in that the viscosity of the TEFLON dispersion is such that it causes the TEFLON to run back down the wire. As the wire is pulled vertically through the heat zone, the agglomerated droplets are fused in place causing beads, nodules, etc. These imperfections cause thickness variations, which make it impossible to thread the TEFLON coated wire through tubes and other equipment during subsequent processing.

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Coating Nodule Free Coatings on Wire

The application of a TEFLON* coating to small diameter wire in a vertical coater presents a control problem, in that the viscosity of the TEFLON dispersion is such that it causes the TEFLON to run back down the wire. As the wire is pulled vertically through the heat zone, the agglomerated droplets are fused in place causing beads, nodules, etc. These imperfections cause thickness variations, which make it impossible to thread the TEFLON coated wire through tubes and other equipment during subsequent processing.

It was found that certain additives would increase the viscosity of and impart a certain thixotropic nature to the TEFLON dispersion. When used in correct amounts, the viscosity was controlled so that there was no sagging or running down the wire during coating and curing; consequently, eliminating the coating imperfections. Using this method, satisfactory concentric coatings were produced having the desirable thickness needed for subsequent operations.

An additional feature obtained by viscosity adjustment, is the fact that the desired product thickness requirement is attainable in one pass through the coater. Prior to this four and five passes were necessary. Still further, the additives having served their purpose are expelled during the fusing operation, and are not retained to any harmful extent in the final coating.

The additives are ammonium Formate, dizmmonium phosphate or ammonium carbonate. These are used in c...