Powdery water-absorbing polymers with fine particles bound by thermoplastic adhesives
View Patent ↗A process for producing and a powdery water-absorbing polymers comprising: about 0.01 to 20 wt. % of a fine particle with a particle size of less than about 200 μm; about 0.001 to 10 wt. % of a thermoplastic adhesive; and about 60 to 99.998 wt. % of a water-absorbing polymer particle with a particle size of about 200 μm and above, wherein the powdery water-absorbing polymers have: a flow value (FFC) within the range from about 1 to 13, and/or a dust portion of at most about 6 are disclosed. Also disclosed are a transport process, a composite, chemical products, and a use of a thermoplastic adhesive.
1. Treated water-absorbing polymer particles comprising:
from about 0.01 to about 20 percent by weight of the polymer of a fine particle with a particle size of less than about 200 μm;
from about 0.001 to less than 0.3 percent by weight of the polymer of a thermoplastic adhesive; and
from about 60 to about 99.998 percent by weight of the polymer of a water-absorbing polymer particle with a particle size of about 200 μm and above, wherein
wherein the treated water-absorbing polymer particles are prepared by a production process and the fine particles are bound to the surface of the water-absorbing polymer particles by the thermoplastic adhesive during the production process for the treated water-absorbing polymer particles, and the treated water-absorbing polymer particles have either
a flow value (FFC) comprising from about 1 to about 13 according to the Determination of the FFC Value set forth in the present application, or
a dust portion comprising at most about 6 according to the Determination of the Dust Portion method set forth in the present application.
2. The treated water-absorbing polymer particles according to claim 1 , wherein the flow value (FFC) comprises from about 1 to about 13 and the dust portion comprises at most about 6, respectively based on the total weight of the powdery water-absorbing polymers.
3. The treated water-absorbing polymer particles according to claim 1 , wherein the thermoplastic adhesive has a melt temperature according to ISO 11357 of at least about 50° C.
4. The treated water-absorbing polymer particles according to claim 1 , wherein the thermoplastic adhesive has a melt viscosity according to Brookfield (ASTM E 28) with a number 27 spindle at a temperature of about 160° C. and less than about 2000 Pas.
5. The treated water-absorbing polymer particles according to claim 1 , wherein the thermoplastic adhesive comprises at least about 10 percent by weight of the adhesive of a polycondensate.
6. The treated water-absorbing polymer particles according to claim 5 , wherein the polycondensate comprises a polyester.
7. The treated water-absorbing polymer particles according to claim 1 , wherein at least about 80 percent by weight of the fine particle comprises an inorganic fine particle.
8. The treated water-absorbing polymer particles according to claim 1 , wherein the water-absorbing polymers include secondary crosslinking in a surface region.
9. The treated water-absorbing polymer particles according to claim 8 , wherein the surface crosslinking in the surface region comprises crosslinking effected by at least one organic compound or at least one polyvalent metal cation.
10. Treated water-absorbing particles obtainable by a process comprising the steps of:
providing from about 0.01 to about 20 percent by weight of a fine particle with a particle size of less than about 200 μm;
providing from about 0.001 to about 0.3 percent by weight of a thermoplastic adhesive;
providing from about 60 to about 99.998 percent by weight of a water-absorbing polymer particle with a particle size of about 200 μm and above; and
wherein the treated water-absorbing polymer particles are prepared by a production process, and contacting the fine particle, the thermoplastic adhesive, and the water-absorbing polymer particle with each other at a temperature comprising from about 120 to about 250° C. during the production process for the treated water-absorbing polymer particles.
11. The treated water-absorbing polymer particles according to claim 10 comprising at least one of the following properties:
P1 a flow value (FFC) comprising from about 1 to about 13; or
P2 a dust portion comprising at most about 6,
P3 an attrition index A i , comprising from about 1 to about 17;
P4 an attrition difference A d comprising from 0 to about 7; or
P5 a retention determined according to ERT 441.1-99 comprising at least about 20 g/g.
12. The treated water-absorbing polymer particles according to claim 1 , wherein at least about 50 percent by weight of the powdery water-absorbing polymers have a particle size comprising from about 50 to about 2,000 μm.
13. A composite comprising the treated water-absorbing polymer particles according to claim 1 .
14. A chemical product comprising the treated water-absorbing polymer particles according to claim 1 .
15. The treated water-absorbing polymer particles according to claim 8 , wherein the water-absorbing polymer particles are contacted with the thermoplastic adhesive and the fine particles during a secondary cross-linking of the water-absorbing polymer particles.
16. A process for producing treated water-absorbing polymer particles comprising the steps of:
providing from about 0.01 to about 20 percent by weight of a fine particle with a particle size of less than about 200 μm;
providing from about 0.001 to less than 0.3 percent by weight of a thermoplastic adhesive;
providing from about 60 to about 99.998 percent by weight of a water-absorbing polymer particle with a particle size of about 200 μm and above; and
contacting the fine particle, the thermoplastic adhesive, and the water-absorbing polymer particle with each other at a temperature comprising from about 120 to about 250° C.
wherein the treated water-absorbing polymer particles have either
a flow value (FFC) comprising from about 1 to about 13 according to the Determination of the FFC Value set forth in the present application, or
a dust portion comprising at most about 6 according to the Determination of the Dust Portion method set forth in the present application.
17. The process for producing treated water-absorbing polymer particles according to claim 16 , wherein the contacting occurs in a continuously conveying mixing oven.
18. The process for producing treated water-absorbing polymer particles according to claim 17 wherein the oven comprises movable, heated conveying means.
19. The process for producing treated water-absorbing polymer particles according to claim 16 further comprising providing a secondary crosslinker and contacting the secondary crosslinker with any one of the fine particle, the thermoplastic adhesive, the water-absorbing polymer particle, or any combination of any of the preceding.
20. The process for producing treated water-absorbing polymer particles according to claim 19 wherein the contacting comprises contacting the secondary crosslinker and the thermoplastic adhesive with the fine particle and the water-absorbing polymer particle.
21. The process for producing treated water-absorbing polymer particles according to claim 19 wherein at least the secondary crosslinker comprises a liquid phase.
22. The treated water-absorbing polymer particles according to claim 1 , wherein the flow value (FFC) or dust portion in said powdery water-absorbing polymer is altered by the process comprising adding a thermoplastic adhesive to the powdery water-absorbing polymer.
23. The treated water-absorbing polymer particles according to claim 1 , wherein said treated water-absorbing polymer particles are transported according to a transport process comprising flowing the treated water-absorbing polymer particles according to claim 1 through a channel.
24. The treated water-absorbing polymer particles according to claim 1 , wherein the flow value (FFC) or dust portion in said powdery water-absorbing polymer is altered by a process comprising adding a thermoplastic adhesive to the powdery water-absorbing polymer.