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Dual Solvent for Polycarbonate

IP.com Disclosure Number: IPCOM000049744D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Edds, KE: AUTHOR [+5]

Abstract

A mixture of methylene chloride and toluene is employed as a solvent vehicle for casting polycarbonate. The addition of toluene lowers the evaporation rate and thereby eliminates the formation of premature surface skin and other debris in the coating equipment.

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Dual Solvent for Polycarbonate

A mixture of methylene chloride and toluene is employed as a solvent vehicle for casting polycarbonate. The addition of toluene lowers the evaporation rate and thereby eliminates the formation of premature surface skin and other debris in the coating equipment.

First, 5.44 parts by weight of MAKROLON 5905* polycarbonate is dissolved in 55.50 parts by weight of methylene chloride. Then 37.00 parts by weight of toluene is added with stirring, followed by 2.00 parts by weight Cabot XC72R** carbon black with stirring. That order of mixing is significant because toluene is not a good solvent for polycarbonate.

This is applied continuously to a substrate with a three-roll reverse coater using pan runs. Evaporation of the methylene chloride and toluene leaves a strong, uniform polycarbonate layer which may be stripped from the substrate.

Methylene chloride as a sole solvent evaporates more rapidly than the foregoing mixture from the coater supply and the coater-head fountain. This rapid evaporation results in surface skin and other debris formation which prevents coating uniformity and interrupts the costing process.

The toluene is believed to be miscible in the methylene chloride solution, but not to contribute to the solubility of the polymer. The foregoing ratio of methylene chloride to toluene is 60/40. That can be reduced at least to 80/20 depending on the extent of the problem of debris formation with a particular coater configuratio...