Water-Absorbing Polymer Structure Surface-Treated with Polycations
The present invention relates to water-absorbing polymer structures, whose surface has been brought into contact with a compound comprising a polycation and at least one anion. The invention further relates to a process for treating the surface of water-absorbing polymer structures, the surface-treated water-absorbing polymer structures obtainable by this process, a composite comprising a surface-treated, water-absorbing polymer structure as well as a substrate, a process for production of a composite, the composite obtainable by this process, chemical products such as foams, formed bodies, and fibers comprising surface-treated water-absorbing polymer structures or a composite, the use of surface-treated, water-absorbing polymer structures or of a composite in chemical products as well as the use of compounds comprising a polycation with a given structure for the treatment of the surface of water-absorbing polymer structures.
1 . A water-absorbing polymer structure, whose surface has been brought into contact with a compound comprising a polycation and at least one anion and which has an absorption under a pressure of 50 g/cm 2 of at least about 16 g/g.
2 . A water-absorbing polymer structure, whose surface has been brought into contact with a compound comprising a polycation and at least one anion, wherein the compound comprising a polycation and at least one anion has a weight average molecular weight of more than about 3,000 g/mol.
3 . The water-absorbing polymer structure according to claim 1 , comprising an inner region and an outer region surrounding the inner region, wherein the outer region has a higher degree of crosslinking than the inner region.
4 . The water-absorbing structure according to claim 1 wherein the polycation has the structure I
in which R 1 and R 2 can be the same or different and represent a hydrocarbon residue with 1 to 10 carbon atoms and n has a value of at least 25.
5 . A polymer structure according to claim 4 wherein R 1 and R 1 represent a methyl group.
6 . The polymer structure according to claim 4 wherein n has a value of at least about 1,000.
7 . The polymer structure according to claim 4 wherein n has a value of at least about 2,000.
8 . The polymer structure according to claim 4 wherein n has a value of at least about 3,000.
9 . The polymer structure according to claim 4 wherein the anion is a chloride ion.
10 . The polymer structure according to claim 4 wherein the polymer structure has at least one of the following properties:
(β1) no caking after three hours;
(β2) with a CRC value of less than about 26 g/g, an SFC value of at least about 80×10 −7 cm 3 s g −1 ;
(β3) with a CRC value within the range from about 26 to less than 27 g/g, an SFC value of at least about 70×10 −7 cm 3 s g −1 ;
(β4) with a CRC value within the range from about 27 to less than 28 g/g, an SFC value of at least about 60×10 −7 cm 3 s g −1 ;
(β5) with a CRC value within the range from about 28 to less than 29 g/g, an SFC value of at least about 45×10 −7 cm 3 s g −1 ;
(β6) with a CRC value within the range from about 29 to less than 30 g/g, an SFC value of at least about 30×10 −7 cm 3 s g −1 ;
(β7) with a CRC value within the range from about 30 to less than 31 g/g, an SFC value of at least about 20×10 −7 cm 3 s g −1 ;
(β8) with a CRC value of at least about 31 g/g, an SFC value of at least about 10×10 −7 cm 3 s g −1 ;
(β9) a Wicking Index after one minute of at least about 7.5 cm;
(β10) a degree of neutralization of at most about 75 mol %.
11 . A process for treatment of the surface of water-absorbing polymer structures, comprising the following steps:
i) providing an untreated water-absorbing polymer structure,
ii) bringing into contact the untreated water-absorbing polymer structure with a compound comprising at least one anion and a polycation, and
iii) post-crosslinking the water-absorbing polymer structure,
wherein the process step iii) can be carried out before, during or after process step ii).
12 . The process according to claim 11 , wherein the polycation has the structure I
in which R 1 and R 2 can be the same or different and represents a hydrocarbon residue with 1 to 10 carbon atoms and
n has a value of at least 25.
13 . The process according to claim 11 wherein the water-absorbing polymer structure is brought into contact with the compound in an amount within a range from about 0.001 to about 10 wt. %, based on the weight of the water-absorbing polymer structure.
14 . The process according to claim 11 wherein the compound is brought into contact with the water-absorbing polymer structure in the form of an about 10 to about 80 wt. % aqueous solution.
15 . The process according to claim 11 wherein the water-absorbing polymer structure has a degree of neutralization of not more than about 70 mol %.
16 . (canceled)
17 . A composite comprising a water-absorbing polymer structure according to claim 1 and a substrate.
18 - 22 . (canceled)
23 . The water-absorbing polymer structure according to claim 2 comprising an inner region and an outer region surrounding the inner region, wherein the outer region has a higher degree of crosslinking than the inner region.
24 . The water-absorbing structure according to claim 2 wherein the polycation has the structure I
in which R 1 and R 2 can be the same or different and represent a hydrocarbon residue with 1 to 10 carbon atoms and n has a value of at least 25.
25 . The polymer structure according to claim 5 wherein n has a value of at least about 1,000.
26 . The polymer structure according to claim 5 wherein n has a value of at least about 2,000.
27 . The polymer structure according to claim 5 wherein n has a value of at least about 3,000.
28 . The polymer structure according to claim 5 wherein the anion is a chloride ion.
29 . The polymer structure according to claim 5 wherein the polymer structure has at least one of the following properties:
(β1) no caking after three hours;
(β2) with a CRC value of less than about 26 g/g, an SFC value of at least about 80×10 −7 cm 3 s g −1 ;
(β3) with a CRC value within the range from about 26 to less than 27 g/g, an SFC value of at least about 70×10 −7 cm 3 s g −1 ;
(β4) with a CRC value within the range from about 27 to less than 28 g/g, an SFC value of at least about 60×10 −7 cm 3 s g −1 ;
(β5) with a CRC value within the range from about 28 to less than 29 g/g, an SFC value of at least about 45×10 −7 cm 3 s g −1 ;
(β6) with a CRC value within the range from about 29 to less than 30 g/g, an SFC value of at least about 30×10 −7 cm 3 s g −1 ;
(β7) with a CRC value within the range from about 30 to less than 31 g/g, an SFC value of at least about 20×10 −7 cm 3 s g −1 ;
(β8) with a CRC value of at least about 31 g/g, an SFC value of at least about 10×10 −7 cm 3 s g −1 ;
(β9) a Wicking Index after one minute of at least about 7.5 cm;
(β10) a degree of neutralization of at most about 75 mol %.
30 . The process according to claim 12 wherein the water-absorbing polymer structure is brought into contact with the compound in an amount within a range from about 0.001 to about 10 wt. %, based on the weight of the water-absorbing polymer structure.
31 . The process according to claim 12 wherein the compound is brought into contact with the water-absorbing polymer structure in the form of a 10 to 80 wt. % aqueous solution.