Process for preparing filter material

Details Process for preparing filter material Process for preparing filter material

1978-05-17

1979-10-16

Lawrence, Evan K.

Coating processes

Foraminous product produced

Filter, sponge, or foam

427246, 427355, 427371, 521 64, 521159, 521163, B05D 500

Patent

active

041713907

ABSTRACT:
A process of producing a porous polyurethane resin filter material. A first solution containing an NCO-adduct dissolved in a highly polar organic solvent is admixed into a second solution containing a highly polar organic solvent and at least one hydrazine hydrate, carbodihydrazide, piperazine and 1,4-diaminopiperazine. The first solution is admixed into the second solution over an extended period of time during which time the viscosity of the admixture is monitored and during which time the NCO pre-adduct and the hydrazine (or the like) react to form a polyurethane reaction product. During this time, the viscosity of the admixture increases. Admixture is continued with monitoring of the viscosity of the admixture until a point is reached at which the addition of even the minutest amount of the first solution into the admixture would result in instantaneous gelling thereof. At this point, the solids content of the final admixture is between 15 and 35% by weight.
The final admixture, which is castable for at least 24 hours, is coated on a textile reinforcing material and the coated material is introduced into a coagulating bath of water with no additives to form a polyurethane sheet structure which is dried to form the porous polyurethane resin filter material in accordance with the invention.

REFERENCES:
patent: 3284274 (1966-11-01), Hulslander et al.
patent: 3595732 (1971-07-01), Tingerthal

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