초록 ▼

Liquid-absorbent polymers are prepared by a process for the gel and/or surface postcrosslinking of water-absorbent polymers by the polymer being treated with a surface postcrosslinking solution and being postcrosslinked and dried during and after the treatment by raising the temperature, wherein the

Liquid-absorbent polymers are prepared by a process for the gel and/or surface postcrosslinking of water-absorbent polymers by the polymer being treated with a surface postcrosslinking solution and being postcrosslinked and dried during and after the treatment by raising the temperature, wherein the surface postcrosslinking solution comprises as crosslinker a compound of the formula I where R1,R2,R3and R4are independently hydrogen, C1-C12-alkyl, C1-C12-alkenyl, C6-C12-aryl or C1-C12-alkoxy, R5is C1-C16-alkyl, C1-C4-hydroxyalkyl, C6-C12-aryl, C1-C16-alkenyl or a group of the formula --(CH2)n--COOH or --(CH2)n--SO3H in the form of the acid or a respective metal salt, ammonium salt or triethanolammonium salt thereof or --(CH2--CH2--O--)m--R6, R6is hydrogen or C1-C16-alkyl, n is from 1 to 10, m is from 1 to 20 dissolved in an inert solvent, and are used in hygiene articles, packaging materials and nonwovens.

대표청구항 ▼

1. A process for the gel and/or surface postcrosslinking of a water-absorbent polymer, comprising: treating said water-absorbent polymer with a surface postcrosslinking solution, to obtain a treated water-absorbent polymer; postcrosslinking said treated water-absorbent polymer to obtain a postcr

1. A process for the gel and/or surface postcrosslinking of a water-absorbent polymer, comprising: treating said water-absorbent polymer with a surface postcrosslinking solution, to obtain a treated water-absorbent polymer; postcrosslinking said treated water-absorbent polymer to obtain a postcrosslinked water-absorbent polymer; and drying said polymer during and after said treating and said crosslinking by raising a temperature; wherein the surface postcrosslinking solution comprises, dissolved in an inert solvent, as crosslinker a compound of formula I wherein R1,R2,R3and R4are each independently hydrogen, C1-C12-alkyl, C1-C12-alkenyl, C6-C12-aryl or C1-C12-alkoxy, R5is C1-C16-alkyl, C1-C4-hydroxyalkyl, C6-C12-aryl, C1-C16-alkenyl or a group of the formula --(CH2)n--COOH or --(CH2)n--SO3H in the form of the acid or a respective metal salt, ammonium salt or triethanolammonium salt thereof or --(CH2--CH2--O--)m--R6, R6is hydrogen or C1-C16-alkyl, n is from 1 to 10, m is from 1 to 20. 2. The process of claim 1, wherein R5is --(CH2)n--COOM or --(CH2)n--SO3M; wherein n=1-10 and M=Na+,K+,NH4+or (HO--CH2--CH2)3NH+. 3. The process of claim 1, wherein said water-absorbent polymer comprises structural units derived from acrylic acid or esters thereof or obtained by graft copolymerization of acrylic acid esters onto a water-soluble polymer matrix. 4. The process of claim 1, wherein surface postcrosslinking is effected using a catalyst comprising an acid or anhydride thereof. 5. The process of claim 4, wherein surface postcrosslinking is effected using a catalyst selected from the group consisting of boric acid, sulfuric acid, hydroiodic acid, phosphoric acid, tartaric acid, acetic acid, toluenesulfonic acid, an acidic salt of boric acid, an acidic salt of sulfuric acid, an acidic salt of hydroiodic acid, an acidic salt of phosphoric acid, an acidic salt of tartaric acid, an acidic salt of acetic acid and an acidic salt of toluenesulfonic acid. 6. The process of claim 1, wherein said inert solvent is water or a mixture of water and from 10 to 90% by weight of a mono- or polyhydric alcohol. 7. The process of claim 1, wherein said crosslinker is used in an amount of from 0.01 to 5% by weight, based on a weight of the polymer. 8. The process of claim 1, wherein in said crosslinker R1,R2,R3and R4are each hydrogen and R5is methyl. 9. A water-absorbent polymer prepared by the process of claim 1. 10. The process of claim 1, wherein said crosslinker of formula I is N-acetyl-2-oxazolidinone. 11. The process of claim 1, wherein said postcrosslinking temperature occurs at a temperature of from 50 to 250° C. 12. The process of claim 1, wherein surface postcrosslinking is effected using a catalyst selected from the group consisting of boron oxide, sulfur trioxide, diphosphorus pentoxide, and ammonium dihydrogenphosphate. 13. The process of claim 1, wherein said inert solvent is an aqueous solution of a member selected from the group consisting of methanol, ethanol, isopropanol, ethylene glycol, 1,2-propanediol and 1,3 propanediol. 14. The process of claim 1, wherein an amount of said surface postcrosslinking solution is 1-20% by weight based a weight of said water-absorbent polymer.