US4824901A — Surface treated absorbent polymers

Claim 1

Independent Claim 220 words

A method of absorbing water comprising mixing a monomer solution of (A) acrylic acid, neutralized 70 to 100 mole percent, (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the weight of acrylic acid and (C) acrylamide in a mole ratio of acrylic acid: acrylamide in the range of 70:30 to 100:0; (D) a water soluble or water miscible polyvinyl monomer cross-linking agent in an amount of 0.001 to 0.3 percent by weight of (A) plus (B) plus (C); and water to form a mixed monomer solution, wherein the monomers of the mixed monomer solution consist essentially of (A), (B), (C) and (D) and the monomer concentration is below 70 percent by weight of the monomer solution prior to polymerization; and initiating polymerization of monomers (A) and (B) such that during polymerization, the exothermic heat of reaction is substantially the only heat energy used to accomplish polymerization, cross-linking and to drive off sufficient water to form a water-absorbent cross-linked polyacrylate resin having a water content of 15 percent by weight or less, followed by contacting said resin with a polyquaternary amine in an amount of from about 0.1% to about 5.0% based on the weight of said resin, and thereafter contacting said polyquaternary amine treated resin with water to absorb water into said treated resin.

Claim 2

Independent Claim 220 words

A method of absorbing water comprising mixing a monomer solution of (A) acrylic acid, neutralized 70 to 100 mole percent, (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the weight of acrylic acid and (C) acrylamide in a mole ratio of acrylic acid: acrylamide in the range of 70:30 to 100:0; (D) a water soluble or water miscible polyvinyl monomer cross-linking agent in an amount of 0.001 to 0.3 percent by weight of (A) plus (B) plus (C); and water to form a mixed monomer solution, wherein the monomers of the mixed monomer solution consist essentially of (A), (B), (C) and (D) and the monomer concentration is below 70 percent by weight of the monomer solution prior to polymerization; and initiating polymerization of monomers (A) and (B) such that during polymerization, the exothermic heat of reaction is substantially the only heat energy used to accomplish polymerization, cross-linking and to drive off sufficient water to form a water-absorbent cross-linked polyacrylate resin having a water content of 15 percent by weight or less, followed by contacting said resin with a polyquaternary amine in an amount of from about 0.1% to about 5.0% based on the weight of said resin, and thereafter contacting said polyquaternary amine treated resin with water to absorb water into said treated resin.

Claim 3

Dependent Claim 30 words

The method as defined in claim 1 wherein the combined concentration of the monomers (A), (B) and (C) is at least 30 wt. % and less than 70 wt. %.

Claim 4

Dependent Claim 23 words

The method as defined in claim 1 wherein the mixed monomer solution has a temperature of 20° to 85° C. prior to polymerization.

Claim 5

Dependent Claim 20 words

The method as defined in claim 1 wherein monomer (C) is selected from the group consisting of N,N-methylenebisacrylamide and N,N-methylenebismethacrylamide.

Claim 6

Dependent Claim 32 words

The method as defined in claim 1 wherein the mixed monomer solution contains 1 to 10 wt. % of an organic solvent based on the weight of monomers (A), (B) and (C).

Claim 7

Dependent Claim 34 words

The method as defined in claim 1 wherein the solid cross-linked resin is treated with from about 0.25% to 2.0% by dry weight of a polyquaternary amine based on the weight of said resin.

Claim 8

Dependent Claim 21 words

The method as defined in claim 1 wherein the polyquaternary amine has a molecular weight from about 200 to about 5000.

Claim 9

Dependent Claim 21 words

The method as defined in claim 1 wherein the polyquaternary amine has a molecular weight from about 300 to about 4000.

Claim 10

Dependent Claim 30 words

The method as defined in claim 1 wherein the polyquaternary amine is a condensation product of hexamethylenediamine, dimethylamine and epichlorohydrin; a condensation product of dimethylamine and epichlorohydrin; or quaternized polyethylenimine.

Claim 11

Dependent Claim 31 words

A process as defined in claim 1 whereby the polyquaternary amine is dispersed in a non-aqeuous solvent from about 0.1% to about 20% by weight before contacting the solid water-absorbent resin.

Claim 12

Dependent Claim 22 words

A process as defined in claim 10 whereby the non-aqueous solvent is methanol, isopropyl alcohol, acetone, methyl ethyl ketone or mixtures thereof.

Claim 13

Dependent Claim 210 words

A process for absorbing water comprising: combining a monomer mixture of (A) potassium acrylate; (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the amount of acrylate computed based on the weight of acrylic acid; and (C) a polyvinyl monomer, with water in an amount of at least 30 combined weight percent of (A) plus (B) plus (C) based on the total weight of (A) plus (B) plus (C) plus water to form a monomer mixture wherein the monomers of the monomer mixture consist essentially of (A), (B) and (C); adding a polymerization initiator to said monomer mixture capable of initiating, and in an amount sufficient to initiate polymerization of said monomer mixture; copolymerizing said monomer mixture while utilizing the exothermic heat of reaction as substantially the only non-ambient energy source to drive water away from said polyacrylate resin copolymer to form said cross-linked resin copolymer having a water content sufficiently low to be powdered without an intermediate drying step; thereafter contacting said cross-linked resin copolymer with a polyquaternary amine in an amount of from about 0.1% to about 5.0% based on the weight of said cross-linked resin copolymer; and thereafter contacting said polyquaternary amine-treated resin with water to absorb water into said treated resin.

Claim 14

Dependent Claim 210 words

A process for absorbing water comprising: combining a monomer mixture of (A) potassium acrylate; (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the amount of acrylate computed based on the weight of acrylic acid; and (C) a polyvinyl monomer, with water in an amount of at least 30 combined weight percent of (A) plus (B) plus (C) based on the total weight of (A) plus (B) plus (C) plus water to form a monomer mixture wherein the monomers of the monomer mixture consist essentially of (A), (B) and (C); adding a polymerization initiator to said monomer mixture capable of initiating, and in an amount sufficient to initiate polymerization of said monomer mixture; copolymerizing said monomer mixture while utilizing the exothermic heat of reaction as substantially the only non-ambient energy source to drive water away from said polyacrylate resin copolymer to form said cross-linked resin copolymer having a water content sufficiently low to be powdered without an intermediate drying step; thereafter contacting said cross-linked resin copolymer with a polyquaternary amine in an amount of from about 0.1% to about 5.0% based on the weight of said cross-linked resin copolymer; and thereafter contacting said polyquaternary amine-treated resin with water to absorb water into said treated resin.

Claim 15

Dependent Claim 35 words

The process of claim 12 further including the step of adjusting the temperature of the monomer mixture to a temperature of 25° to 85° C. prior to adding said polymerization initiator to said monomer mixture.

Claim 16

Dependent Claim 29 words

The process of claim 12 wherein said polymerization initiator is added in an amount of at least 0.5% based on the total weight of monomers (A), (B) and (C).

Claim 17

Dependent Claim 33 words

The process of claim 12 wherein the water content of said cross-linked resin copolymer is not greater than about 10% by weight as recovered from the polymerized mixture, without an additional drying step.

Claim 18

Dependent Claim 26 words

The process of claim 12 including the step of pulverizing said cross-linked resin to form a powder prior to contacting said powder with said polyquaternary amine.

Claim 19

Dependent Claim 32 words

The process of claim 12 wherein the cross-linked resin copolymer is treated with from about 0.25% to about 2.0% of the polyquaternary amine based on the weight of said cross-linked resin copolymer.

Claim 20

Dependent Claim 32 words

The process of claim 16 wherein the cross-linked resin copolymer is treated with from about 0.25% to about 2.0% of a polyquaternary amine based on the weight of said cross-linked resin copolymer.

Claim 21

Dependent Claim 19 words

The process of claim 12 wherein the polyquaternary amine has a molecular weight from about 200 to about 5000.

Claim 22

Dependent Claim 19 words

The process of claim 12 wherein the polyquaternary amine has a molecular weight from about 500 to about 3000.

Claim 23

Dependent Claim 28 words

The process of claim 12 wherein the polyquaternary amine is a condensation product of hexamethylenediamine, dimethylamine and epichlorohydrin; a condensation product of dimethylamine and epichlorohydrin; or quaternized polyethylenimine.

Claim 24

Dependent Claim 27 words

The process of claim 12 wherein the polyquaternary amine is dispersed in methanol from about 0.1% to about 20% by weight before contacting the cross-linked resin copolymer.

Claim 25

Independent Claim 208 words

A method of absorbing water comprising mixing a monomer solution of (A) acrylic acid, neutralized 70 to 100 mole percent, (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the weight of acrylic acid and (C) acrylamide in a mole ratio of (A):(C) in the range of 70:30 to 100:0; (D) a water soluble or water miscible polyvinyl monomer cross-linking agent in an amount of 0.001 to 0.3 percent by weight of (A) plus (B) plus (C); and water to form a mixed monomer solution, wherein the monomers of the mixed monomer solution consist essentially of (A), (B), (C) and (D); and initiating polymerization of monomers (A), (B) and (C) such that during polymerization, the exothermic heat of reaction is substantially the only heat energy used to accomplish polymerization, cross-linking and to drive off sufficient water to form a water-absorbent cross-linked polyacrylate resin composition having a water content of 15 percent by weight or less; thereafter contacting said water-absorbent cross-linked polyacrylate resin with a polyquaternary amine in an amount sufficient to increase the water absorbency of said resin based on the weight of said water-absorbent cross-linked polyacrylate; and thereafter contacting said polyquaternary amine-treated resin with water to absorb water into said treated resin.

Claim 26

Independent Claim 208 words

A method of absorbing water comprising mixing a monomer solution of (A) acrylic acid, neutralized 70 to 100 mole percent, (B) styrene and/or methyl methacrylate in an amount of 0% to 25% based on the weight of acrylic acid and (C) acrylamide in a mole ratio of (A):(C) in the range of 70:30 to 100:0; (D) a water soluble or water miscible polyvinyl monomer cross-linking agent in an amount of 0.001 to 0.3 percent by weight of (A) plus (B) plus (C); and water to form a mixed monomer solution, wherein the monomers of the mixed monomer solution consist essentially of (A), (B), (C) and (D); and initiating polymerization of monomers (A), (B) and (C) such that during polymerization, the exothermic heat of reaction is substantially the only heat energy used to accomplish polymerization, cross-linking and to drive off sufficient water to form a water-absorbent cross-linked polyacrylate resin composition having a water content of 15 percent by weight or less; thereafter contacting said water-absorbent cross-linked polyacrylate resin with a polyquaternary amine in an amount sufficient to increase the water absorbency of said resin based on the weight of said water-absorbent cross-linked polyacrylate; and thereafter contacting said polyquaternary amine-treated resin with water to absorb water into said treated resin.

Claim 27

Dependent Claim 31 words

The method of claim 23 wherein the cross-linked polyacrylate resin is contacted with the polyquaternary amine in an amount of 0.1% to 5.0% based on the total weight of contacted resin.

Claim 28

Dependent Claim 37 words

The method of claim 23 wherein the water content of said cross-linked polyacrylate resin copolymer is not greater than about 10% by weight as recovered from the mixed monomer solution after copolymerization, without an additional drying step.

Claim 29

Dependent Claim 60 words

The method of claim 23 including depositing said monomer mixture including said initiator onto a support surface in sheet form for polymerization and cross-linking, followed by pulverizing the resultant cross-linked resin to form a powder, and thereafter contacting said powder with a polyquaternary amine in an amount of from about 0.1% to 5.0% based on the weight of said powder.

Claim 30

Independent Claim 57 words

A method of absorbing water comprising surface treating a water-absorbent resin containing neutralized carboxyl, neutralized sulfonate, neutralized phosphate, amide or nitrite functionalities with a sufficient amount of a polyquaternary amine to substantially increase the water absorption of said water-absorbent resin, and thereafter contacting said polyquaternary amine treated resin with water to absorb water into said treated resin.

Claim 31

Independent Claim 57 words

A method of absorbing water comprising surface treating a water-absorbent resin containing neutralized carboxyl, neutralized sulfonate, neutralized phosphate, amide or nitrite functionalities with a sufficient amount of a polyquaternary amine to substantially increase the water absorption of said water-absorbent resin, and thereafter contacting said polyquaternary amine treated resin with water to absorb water into said treated resin.

Claim 32

Dependent Claim 14 words

The method according to claim 27 wherein the water-absorbent resin contains neutralized carboxyl functionalities.

Claim 33

Dependent Claim 26 words

The method according to claim 27 wherein the water-absorbent resin is treated with from about 0.1% to about 5.0% by dry weight of a polyquaternary amine.

Claim 34

Dependent Claim 26 words

The method according to claim 27 wherein the water-absorbent resin is treated with from about 0.25% to about 2% by dry weight of a polyquaternary amine.

Claim 35

Dependent Claim 19 words

The method of claim 27 wherein the polyquaternary amine has a molecular weight from about 200 to about 5000.

Claim 36

Dependent Claim 19 words

The method of claim 27 wherein the polyquaternary amine has a molecular weight from about 300 to about 4000.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-04-24	1992-10-24	1993-04-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-04-24	1996-10-24	1997-04-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-04-24	2000-10-24	2001-04-25	$7700.00	Window Closed / Lapsed

Surface treated absorbent polymers

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