US5086133A — Process for producing highly water absorptive pol…

Claim 1

Independent Claim 156 words

A process for producing a highly water absorptive polymer, which comprises: preparing a mixture (A) comprising an aqueous solution of (a) a partially neutralized product of acrylic acid with 20% or more of carboxylic groups being neutralized to an alkali metal salt or ammonium salt, (b) a crosslinking agent having two or more copolymerizable vinyl groups in one molecule, (c) a basic vinyl monomer in a quantity of 20 mol % or less based on said partially neutralized product of acrylic acid, (d) a nonionic surfactant with HLB of 7 or more and (e) an oxidative radical polymerization initiator, said mixture (A) being maintained at a temperature of 50° C. or lower, and a mixture (B) comprising an amine or a reducing agent dissolved in water or in said mixture (A) from which at least the component (e) is removed; and mixing both the mixtures and conducting polymerization at a temperature of 30° to 50° C.

Claim 2

Dependent Claim 156 words

A process for producing a highly water absorptive polymer, which comprises: preparing a mixture (A) comprising an aqueous solution of (a) a partially neutralized product of acrylic acid with 20% or more of carboxylic groups being neutralized to an alkali metal salt or ammonium salt, (b) a crosslinking agent having two or more copolymerizable vinyl groups in one molecule, (c) a basic vinyl monomer in a quantity of 20 mol % or less based on said partially neutralized product of acrylic acid, (d) a nonionic surfactant with HLB of 7 or more and (e) an oxidative radical polymerization initiator, said mixture (A) being maintained at a temperature of 50° C. or lower, and a mixture (B) comprising an amine or a reducing agent dissolved in water or in said mixture (A) from which at least the component (e) is removed; and mixing both the mixtures and conducting polymerization at a temperature of 30° to 50° C.

Claim 3

Dependent Claim 48 words

The process according to claim 1, wherein the mixture (A) and the mixture (B) are mixed on a movable belt or prior to feeding onto a movable belt, and fed onto the movable belt to a thickness of 10 mm or less to cause polymerization on said belt.

Claim 4

Dependent Claim 60 words

The process according to claim 1, wherein the partially neutralized product of acrylic acid (a) is one of which 40 to 70% of the carboxylic groups of the acrylic acid are neutralized to sodium salt and (or) potassium salt and the concentration of said partially neutralized product of acrylic acid in the aqueous solution is less than 65% by weight.

Claim 5

Dependent Claim 31 words

The process according to claim 3, wherein the partially neutralized product of acrylic acid (a) is obtained by neutralization of acrylic acid monomer with sodium hydroxide, potassium hydroxide or mixtures thereof.

Claim 6

Dependent Claim 35 words

The process according to claim 1, wherein the partially neutralized product of acrylic acid (a) is one of which 90% or more the carboxylic groups of the acrylic acid are neutralized to the ammonium salt.

Claim 7

Dependent Claim 26 words

The process according to claim 5, wherein the partially neutralized product of acrylic acid (a) is obtained by neutralization of acrylic acid monomer with ammonium hydroxide.

Claim 8

Dependent Claim 27 words

The process according to claim 1, wherein the crosslinking agent is selected from the group consisting of N,N'-methylenebis(meth)acrylamide, polyethylene glycol di(meth)acrylate and tetramethylolmethane tetraacrylate and mixtures thereof.

Claim 9

Dependent Claim 36 words

The process according to claim 1, wherein the amount of the crosslinking agent (b) used is 0.01 to 1 part by weight per 100 parts by weight of the partially neutralized product of acrylic acid (a).

Claim 10

Dependent Claim 28 words

The process according to claim 1, wherein the basic vinyl monomer (c) is selected from the group consisting of (meth)acrylamide, N,N'-dimethylmethacrylamide, dimethylaminoethyl(meth)acrylamide, 2-vinylpyridine and 4-vinylpyridine and mixtures thereof.

Claim 11

Dependent Claim 16 words

The process according to claim 1, wherein the nonionic surfactant (d) is a polyoxyethylene acyl ester.

Claim 12

Dependent Claim 23 words

The process according to claim 10, wherein the nonionic surfactant (d) is a polyethylene glycol dilaurate with HLB value of 10 or more.

Claim 13

Dependent Claim 36 words

The process according to claim 1, wherein the amount of the nonionic surfactant (d) used is 0.01 to 5 parts by weight per 100 parts by weight of the partially neutralized product of acrylic acid (a).

Claim 14

Dependent Claim 51 words

The process according to claim 1, wherein the oxidative radical initiator (e) is selected from the group consisting of (i) hydrogen peroxide, (ii) persulfates selected from ammonium persulfate, potassium persulfate and sodium persulfate, (iii) hydroperoxides selected from tert-butyl hydroperoxide and cumene hydroperoxide, and (iv) secondary cerium salts, permanganates, chlorites and hypochlorites.

Claim 15

Dependent Claim 32 words

The process according to claim 1, wherein the amount of the oxidative radical initiator (e) used is 0.1 to 2% by weight based on the partially neutralized product of acrylic acid (a).

Claim 16

Dependent Claim 72 words

The process according to claim 1, wherein the amine or reducing agent dissolved in the mixture (B) is selected from the group consisting of (i) a primary amine selected from aniline, monoethanolamine and hexanemethylenediamine, (ii) a secondary amine selected from diethanolamine, (iii) a sulfite selected from sodium hydrogen sulfite and sodium sulfite and (iv) sodium thiosulfate, cobalt acetate, cupric sulfate, ferrous sulfate, L-ascorbic acid and an alkali metal salt of L-ascorbic acid.

Claim 17

Dependent Claim 32 words

The process according to claim 1, wherein the amount of the amine or reducing agent used is 0.01 to 2% by weight based on the partially neutralized product of acrylic acid (a).

Claim 18

Dependent Claim 31 words

The process according to claim 1, wherein the oxidative radical polymerization initiator (e) is hydrogen peroxide and the reducing agent is L-ascorbic acid or an alkali metal salt of L-ascorbic acid.

Claim 19

Dependent Claim 25 words

The process according to claim 1, wherein the mixing ratio of the mixture (A) to the mixture (B) is 99:1 to 10:90 (% by volume).

Claim 20

Dependent Claim 18 words

The process according to claim 1, wherein the polymerization is carried out for several seconds to one minute.

Claim 21

Dependent Claim 177 words

A process for producing a highly water absorptive polymer, which comprises: (A) preparing a mixture of an aqueous solution of (i) a partially neutralized product of acrylic acid with at least 20% of carboxylic groups being neutralized in the form of an alkali metal salt or an ammonium salt, (ii) a crosslinking agent having at least two copolymerizable vinyl groups in one molecule, (iii) a basic vinyl monomer in an amount of no more than 20 mol % based on said partially neutralized acrylic acid, (iv) a nonionic surfactant with an HLB value of at least 7 and (v) an oxidative radical polymerization initiator, said mixture being maintained at a temperature of no more than 50° C.; (B) preparing a mixture of an amine or a reducing agent dissolved in water; (C) mixing both of said mixtures in a vessel; and (D) feeding said mixed solution from said vessel onto a movable belt to a thickness of no more than 10 mm in order to polymerize the polymerizable ingredients at a temperature of 30° to 50° C.

Claim 22

Dependent Claim 177 words

A process for producing a highly water absorptive polymer, which comprises: (A) preparing a mixture of an aqueous solution of (i) a partially neutralized product of acrylic acid with at least 20% of carboxylic groups being neutralized in the form of an alkali metal salt or an ammonium salt, (ii) a crosslinking agent having at least two copolymerizable vinyl groups in one molecule, (iii) a basic vinyl monomer in an amount of no more than 20 mol % based on said partially neutralized acrylic acid, (iv) a nonionic surfactant with an HLB value of at least 7 and (v) an oxidative radical polymerization initiator, said mixture being maintained at a temperature of no more than 50° C.; (B) preparing a mixture of an amine or a reducing agent dissolved in water; (C) mixing both of said mixtures in a vessel; and (D) feeding said mixed solution from said vessel onto a movable belt to a thickness of no more than 10 mm in order to polymerize the polymerizable ingredients at a temperature of 30° to 50° C.

Claim 23

Dependent Claim 184 words

A process for producing a highly water absorptive polymer, which comprises: (A) preparing a mixture of an aqueous solution of (i) a partially neutralized product of acrylic acid with at least 20% of carboxylic groups being neutralized in the form of an alkali metal salt or an ammonium salt, (ii) a crosslinking agent having at least two copolymerizable vinyl groups in one molecule, (iii) a basic vinyl monomer in an amount of no more than 20 mol % based on said partially neutralized acrylic acid, (iv) a nonionic surfactant with an HLB value of at least 7 and (v) an oxidative radical polymerization initiator, said mixture being maintained at a temperature of no more than 50° C.; (B) preparing a mixture of an amine or a reducing agent dissolved in water; (C) feeding said neutralized acrylic acid containing mixture onto a movable belt to a thickness of no more than 10 mm; and thereafter (D) spraying the mixture containing the reducing agent onto the material on said movable belt thereby conducting polymerization of the polymerizable ingredients at a temperature of 30° to 50° C.

Claim 24

Dependent Claim 184 words

A process for producing a highly water absorptive polymer, which comprises: (A) preparing a mixture of an aqueous solution of (i) a partially neutralized product of acrylic acid with at least 20% of carboxylic groups being neutralized in the form of an alkali metal salt or an ammonium salt, (ii) a crosslinking agent having at least two copolymerizable vinyl groups in one molecule, (iii) a basic vinyl monomer in an amount of no more than 20 mol % based on said partially neutralized acrylic acid, (iv) a nonionic surfactant with an HLB value of at least 7 and (v) an oxidative radical polymerization initiator, said mixture being maintained at a temperature of no more than 50° C.; (B) preparing a mixture of an amine or a reducing agent dissolved in water; (C) feeding said neutralized acrylic acid containing mixture onto a movable belt to a thickness of no more than 10 mm; and thereafter (D) spraying the mixture containing the reducing agent onto the material on said movable belt thereby conducting polymerization of the polymerizable ingredients at a temperature of 30° to 50° C.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-02-03	1995-08-05	1996-02-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-02-03	1999-08-05	2000-02-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-02-03	2003-08-05	2004-02-04	$7700.00	Window Closed / Lapsed

Process for producing highly water absorptive polymer

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag