Abstract A method for producing a microporous sheet material having excellent abrasion resistance and moisture-permeability useful for artificial leathers wherein numerous bead-like linked spherical micropores are arranged contiguously at barrier intervals in the interior of the microporous layer is proposed. A coating solution of a polymer predominantly comprising polyurethane elastomer containing an inorganic salt selected from among sodium chloride, sodium sulphate, potassium chloride and potassium sulphate and a higher aliphatic carboxylic acid selected from among stearic acid, palmitic acid and myristic acid is applied to a base sheet material, then coagulated in a coagulating bath comprising water or an aqueous solution of said inorganic salt, washed and dried. Thus-obtained microporous sheet may be further subjected to buffing or grinding to produce a suede-like sheet material, if required.
A method according to claim 1 wherein said liquid coating material contains inorganic salt in an amount in a range of 150 to 400 percent by weight based on the weight of the polyurethane.
Claim 2
Dependent Claim
56 words
immersing the coated base material in a liquid coagulating bath selected from the group consisting of water and an aqueous solution of said inorganic salt having a salt concentration of less than two-thirds the concentration of a saturated aqueous solution of said salt, said bath having a temperature in the range of from 5* to 50*C;
Claim 3
Dependent Claim
14 words
and then washing and drying the coagulated material to obtain the microporous sheet material.
Claim 4
Dependent Claim
24 words
A method according to claim 1 wherein said inorganic salt is sodium chloride or sodium sulphate and said aliphatic carboxylic acid is stearic acid.
Claim 5
Dependent Claim
37 words
A method according to claim 1 wherein said aqueous solution of the inorganic salt, as a coagulating bath, has a concentration of not more than one-third of the concentration of a saturated aqueous solution of said salt.
Claim 6
Dependent Claim
21 words
A method according to claim 1 wherein the temperature of the coagulating bath is in a range of 20* to 40*C.
Claim 7
Dependent Claim
23 words
A method according to claim 1 wherein the inorganic salt in the coating solution is the same as that in the coagulating bath.
Claim 8
Dependent Claim
16 words
A method according to claim 1 wherein said polymer consists essentially of a polyester polyurethane elastomer.
Claim 9
Dependent Claim
13 words
A method according to claim 6 wherein the inorganic salt is sodium chloride.