Absorbent compositions

Claim 2

A process for preparing a composition capable of absorbing substantial quantities of liquids which comprises polymerizing at an acidic pH acrylonitrile or methacrylonitrile in the presence of about 0.03 to 5.0% by weight thereof of a polyfunctional monomeric cross-linking agent containing at least two polymerizable ethylenic groups per molecule, saponifying the resulting polymer with an aqueous alcoholic solution of an alkali base and recovering a granular, substantially water-insoluble liquid absorbing composition.

Claim 3

A process in accordance with claim 1 wherein the cross-linking agent is incorporated with the acrylonitrile or methacrylonitrile prior to initiation of polymerization.

Claim 4

A process in accordance with claim 1 wherein the cross-linking agent is incorporated with the acrylonitrile or methacrylonitrile subsequent to initiation of polymerization.

Claim 5

A process in accordance with claim 1 wherein an aqueous methanol solution of an alkali base is employed for saponification.

Claim 6

A process in accordance with claim 1 wherein the polymerization is conducted at an acidic pH and at a temperature of not more than about 100° C. for a period of not less than about 0.1 hour.

Claim 7

A process in accordance with claim 1 wherein the polymerization is conducted at an acidic pH and at a temperature of not more than about 80° C. for a period of not less than about 0.1 hour.

Claim 8

A process in accordance with claim 1 wherein a surfactant is employed in the polymerization.

Claim 9

A process in accordance with claim 7 wherein the surfactant is tetrasodium-N-(1,2-dicarboxyethyl)-N-octadecyl sulfosuccinamate.

Claim 10

A process in accordance with claim 1 wherein the cross-linking agent is N,N'-methylene-bis-acrylamide.

Claim 11

A process in accordance with claim 1 wherein the cross-linking agent is employed in an amount of about 0.05 to 2.0% by weight of acrylonitrile or methacrylonitrile.

Claim 12

A process in accordance with claim 1 wherein a polymerization initiator is employed.

Claim 13

A process in accordance with claim 11 wherein the polymerization initiator is a ceric salt.

Claim 14

A process in accordance with claim 11 wherein the polymerization initiator is a redox catalyst system including an oxidizing agent and a reducing agent.

Claim 15

A process in accordance with claim 13 wherein a multivalent metal ion is included to promote polymerization.

Claim 16

A process in accordance with claim 11 wherein the polymerization initiator comprises ammonium persulfate, sodium metabisulfite and ferrous ammonium sulfate.

Claim 17

A process for preparing a composition capable of absorbing substantial quantities of liquids which comprises: (1) forming an aqueous mixture containing from about 2 to 40% by weight acrylonitrile or methacrylonitrile, (2) adding to said aqueous mixture a polyfunctional monomeric cross-linking agent containing at least two polymerizable ethylenic groups per molecule prior to or subsequent to initiation of polymerization in an amount from about 0.03 to 5.0% by weight of acrylonitrile or methacrylonitrile, (3) adjusting the pH of the reaction mixture to pH 1-4, (4) adding to the acidic aqueous mixture a polymerization initiator, (5) allowing the polymerization reaction to proceed for a period of not less than about 0.1 hour at a temperature not above about 100° C., and (6) saponifying the recovered polymerized product with an aqueous alcoholic solution of a base.

Claim 18

A process for preparing a composition capable of absorbing substantial quantities of liquids which comprises: (1) forming an aqueous mixture containing from about 2 to 40% by weight acrylonitrile or methacrylonitrile, (2) adding to said aqueous mixture a polyfunctional monomeric cross-linking agent containing at least two polymerizable ethylenic groups per molecule prior to or subsequent to initiation of polymerization in an amount from about 0.03 to 5.0% by weight of acrylonitrile or methacrylonitrile, (3) adjusting the pH of the reaction mixture to pH 1-4, (4) adding to the acidic aqueous mixture a polymerization initiator, (5) allowing the polymerization reaction to proceed for a period of not less than about 0.1 hour at a temperature not above about 100° C., and (6) saponifying the recovered polymerized product with an aqueous alcoholic solution of a base.

Claim 19

A process in accordance with claim 16 wherein in step (1) the aqueous mixture contains from about 5 to 25% by weight acrylonitrile or methacrylonitrile.

Claim 20

A process in accordance with claim 16 wherein the cross-linking agent is employed in an amount of from about 0.05 to 2.0% by weight of acrylonitrile or methacrylonitrile.

Claim 21

A process in accordance with claim 16 wherein the cross-linking agent is N,N'-methylene-bis-acrylamide.

Claim 22

A process in accordance with claim 16 wherein the polymerization initiator is a redox catalyst system comprised of an oxidizing agent and a reducing agent.

Claim 23

A process in accordance with claim 16 wherein a multivalent metal ion polymerization promoter is added in an amount of from about 0.005 to 0.5% by weight based upon the acrylonitrile or methacrylonitrile.

Claim 24

A process in accordance with claim 16 wherein a surfactant is added to the mixture.

Claim 25

A substantially water-insoluble solid liquid-absorbing composition comprising an alkali metal salt of an aqueous alcoholic alkali saponified cross-linked homopolymer of acrylonitrile or methacrylonitrile.

Claim 26

A substantially water-insoluble solid liquid-absorbing composition comprising an alkali metal salt of an aqueous alcoholic alkali saponified cross-linked homopolymer of acrylonitrile or methacrylonitrile.

Claim 27

A composition in accordance with claim 23 wherein the homopolymer of acrylonitrile or methacrylonitrile is cross-linked with N,N'-methylene-bis-acrylamide.

Claim 28

A composition in accordance with claim 23 wherein the liquid-absorbing composition is an alkali metal salt of an aqueous methanolic alkali saponified cross-linked homopolymer of acrylonitrile or methacrylonitrile.