Process for preparing microporous,open-celled cellular polyamide,polyester and polyacetal structures

Claim 2

A process according to claim 1 wherein from about 0.3 to about 50 weight per volume percent of a normally solid polymer selected from the group consisting of polyamide, polyester and polyacetal is dissolved in the selected solvent.

Claim 3

The process of claim 1 in which the solvent is removed by evaporation and the chlorofluorocarbon is removed by sublimation at a temperature of from about 0* C. to the solidification temperature of the chlorofluorocarbon.

Claim 4

The process of claim 1 further comprising mixing water with the cooled dispersion of claim 1(c) to form a solvent-water phase and a polymer-chlorofluorocarbon mixture, removing the solvent-water phase by decantation; and removing the chlorofluorocarbon by sublimation at a temperature of from about 0* C. to the solidification temperature of the chlorofluorocarbon.

Claim 5

The process of claim 1 further comprising mixing water with the cooled dispersion of claim 1(c) to form a solvent-water phase and a polymer-chlorofluorocarbon mixture; removing the solvent-water phase by decantation; removing substantially all of the chlorofluorocarbon by aspiration at a temperature at which the chlorofluorocarbon is liquid; and removing any residual chlorofluorocarbon by vaporization.

Claim 6

The process of claim 1 in which the starting polymer is selected from the group poly(hexamethyleneadipamide), poly(ethylene terephthalate) and polyoxymethylene.

Claim 7

The process of claim 1 in which the chlorofluorocarbon is at least one of 1,1,2,2-tetrachloro-1,2-difluoroethane and 1,1,1,2-tetrachloro-2,2-difluoromethane.

Claim 8

A process of claim 1 in which the amount of the chlorofluorocarbon used is such that the resulting polymeric microporous, open-celled, cellular structure is coherent.

Claim 9

A process of claim 1 in which the amount of the chlorofluorocarbon used is such that the resulting polymeric microporous, open-celled, cellular structure is particulate.

Claim 10

A process according to claim 1 further comprising adding to the dispersion of the chlorofluorocarbon in the polymer solution prior to the cooling step a chlorofluorocarbon miscible anionic, cationic or nonionic surfactant in an amount of up to 3 weight per volume percent of said dispersion.

Claim 11

A process according to claim 11 wherein the surface active agent is anionic and is selected from the group consistinG of fatty carboxylic acids, sulfuric esters, alkane sulfonic acids and alkylarylsulfonic acids.

Claim 12

A process according to claim 11 wherein the surface active agent is cationic and is selected from the group consisting of fatty amines and quaternary ammonium compounds.

Claim 13

A process according to claim 11 wherein the surface active agent is monionic and is selected from the group consisting of polyoxyalkylene ethers of higher fatty acids and alkylphenols.

Claim 14

A dispersion of a polymer selected from th group consisting of polyamide, polyester and polyacetal prepared by a. dissolving at least 0.3 weight per volume percent of the selected polymer in a solvent selected from the group consisting of hexafluoropropyl alcohol, hexafluoroacetone hydrate, formic acid, and mixtures thereof to form a polymer solution, with the proviso that formic acid is utilized either alone or in mixture only when the selected polymer is polyamide, and (b) dispersing in the resulting solution from about one to about 10 times its volume of a liquid chlorofluorocarbon or mixture of chlorofluorocarbons having a boiling point in the range of from about 10* to 150* C., a melting point in the range of from about -40* to 125* C., an entropy of fusion of less than 10 calories/*K/mole, a plastic flow index of at least 0.1 g./10 min. at the reduced temperature of 0.96 to 0.99, and a solubility in water of less than about 2 weight percent at a temperature below the atmospheric boiling temperature of the lowest-boiling component of the polymer solution, to form a dispersion.

Claim 15

A dispersion according to claim 15 wherein the chlorofluorocarbon or mixture of chlorofluorocarbons is selected from the group consisting of 1,1,1,2,2-pentachloro-2-fluoroethane, 1,1,2,2-tetrachloro-1,2-difluoroethane, 1,1,1,2-tetrachloro-2,2-difluoroethane, 1,1,1-trichloro-2,2,2-trifluoroethane, 1,2dichlorodecafluorocyclohexane, 1,1,2,2-tetrachloro-perfluorocyclobutane, 1,2-dichloroperfluorocyclobutane, 1-chloroperfluorocyclobutane, 1,1, 2-trichloro-1,2,2-trifluoroethane, 1,1,1,3-tetrafluoro-2,2,3,3-tetrachloropropane, 1,1,1,3,3-pentafluoro-2,2,3-trichloropropane, 1,1,1,3,3,3-hexafluoro-2,2-dichloropropane, 1,1,1,4,4,4-hexafluoro-2,2,3,3-tetrachlorobutane and mixtures thereof.

Claim 16

A plastic, pliable, moldable, and extrudable composition of matter obtained by a. cooling the dispersion of claim 15 to at least the solidification temperature of the lowest-melting chlorofluorocarbon present; b. mixing with the cooled dispersion sufficient water to substantially precipitate the polymer; and c. removing the solvent-water phase.