Production of porous materials
AssigneePorvair PLC
InventorDavid L. Boutle
Life of this patent
Estimating the term…
Abstract
An improved microporous polymer material is made by coagulating, e.g. in water, a polymer solution containing dispersed microscopic particles of a removable filler soluble in a coagulating liquid.
Claims27
A method of making a microporous polymeric plastics material which comprises
- (a) forming a mixture comprising a solution of elastomeric polyurethane in water-miscible organic solvent, the said solution having evenly distributed through its microscopic particles of water-soluble inorganic salt,
- (b) shaping the mixture into a layer, and
- (c) solidifying said polyurethane by the action of aqueous non-solvent therefor, which is miscible with the organic solvent, and leaching out said microscopic particles of the salt to leave the elastomeric polyurethane in a microporous solid form, as a layer, the weight ratio of salt to polyurethane being up to about 6:1.
A process for producing a porous sheet material which comprises (a) uniformly dispersing from about 10 to about 50 parts by weight of an inorganic salt in 100 parts by weight of a film-forming polyester type polyurethane, (b) applying the coating solution on a fibrous substrate or a film-making plate, (c) coagulating the coating layer with an aqueous coagulation medium, the concentration of said inorganic salt in said coagulating medium being below about two-thirds its concentration at saturation, and at least sufficient to yield a porous sheet upon coagulation of said polyurethane, said inorganic salt being selected from the group consisting of sodium sulfate and sodium chloride.
A process for producing a porous sheet material which comprises (a) uniformly dispersing from about 10 to about 50 parts by weight of an inorganic salt in 100 parts by weight of a film-forming polyester type polyurethane, (b) applying the coating solution on a fibrous substrate or a film-making plate, (c) coagulating the coating layer with water to yield a porous sheet upon coagulation of said polyurethane, said inorganic salt being selected from the group consisting of sodium sulfate and sodium chloride.
In a process for producing an artificial leather by applying a polyurethane polymer solution in an organic solvent as a coating layer onto a textile substrate, bathing the coated layer with a nonsolvent for the polymer until the layer has coagulated and then washing and drying to obtain a porous elastomeric layer, the improvement which comprises:
- carrying out said coating application with a solution of said polyurethane containing 21 to 33 parts by weight of polyurethane and 300 to 600% by weight, with reference to the polyurethane, of sodium sulfate in 79 to 67 parts by weight of an organic solvent which is miscible with water and which is a nonsolvent for sodium sulfate, the viscosity of said solution being at least 20 poises, measured at 20.degree. C.;
- and subsequently washing out said solvent and said sodium sulfate from the coagulated layer and drying to form an elastomeric coating permeated with micropores.
Dependencies are inferred from the claim text.