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Increasing Useful Life of Polyurethanes

IP.com Disclosure Number: IPCOM000080946D
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

Arrington, EL: AUTHOR

Abstract

Stability of polyurethane material against hydrolysis is improved at least two-fold in hot humid environments. A sample or unit coated with previously cured polyurethane is soaked in a solution of 30% by weight polycarbodiimide antioxidant (e.g., Stabaxol* PCD) and 70% by weight toluene, acetone, Laminar X-500**, Reducer 66-C-28, xylene, S-8*** or dioxane solvent; whereupon the coated sample or unit is dried at room temperature in a partially closed hood without an exhaust, then baked at 100 degrees C for 24 to 48 hours.

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Increasing Useful Life of Polyurethanes

Stability of polyurethane material against hydrolysis is improved at least two- fold in hot humid environments. A sample or unit coated with previously cured polyurethane is soaked in a solution of 30% by weight polycarbodiimide antioxidant (e.g., Stabaxol* PCD) and 70% by weight toluene, acetone, Laminar X-500**, Reducer 66-C-28, xylene, S-8*** or dioxane solvent; whereupon the coated sample or unit is dried at room temperature in a partially closed hood without an exhaust, then baked at 100 degrees C for 24 to 48 hours.

Tests showed that the hydrolysis stability of a two-year old cured conformal coating material on a coated unit was improved 2.45 lifetimes in a test environment of 90 degrees C and 95% relative humidity, when treated with a 30% solution of polycarbodiimide in toluene followed by overcoating with the same material plus an 8% polycarbodiimide spray mixture. This improvement was achieved without lose of coating flexibility or repairability.

Results are, of course, more effective if the polycarbodiimide is added directly to the polyester-urethane. For example, when 8% by weight polycarbodiimide was added directly to the polyester-urethane, the polyurethane was stabilized against attack by water to the extent that its stability toward hydrolysis was increased 5.5 lifetimes, at 97 degrees C and 95% relative humidity. * Trade name of Naftone, Inc. of New York City ** Trade name of Magna Coating & Chemical Corp. o...