The present invention provides a method for being capable of sufficiently exerting property improvement effect by the addition of additive particles other than water-absorbing resin to water-absorbing resin particles. The problems can be solved by using additive particles having over cohesive particles in an amount equal to or less than a predetermined amount, or by using the additive particles by crushing or classifying in advance, before mixing with water-absorbing resin particles. Alternatively, the problem can be solved by subjecting a mixture of the water-absorbing resin particles and the additive particles to pneumatic transportation processing, in particular, in a heated state, after mixing or at the same time as mixing. Further, the present invention provides a water-absorbing resin composition, which is capable of stably exerting high-level property. The problems can be solved by a water-absorbing resin composition, where the addition amount of additive particles and amount of free additive particles satisfies a predetermined relation.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an outline view showing one embodiment of a high concentration pneumatic conveying apparatus.
Claims
1. A method for producing a water-absorbing resin composition, comprising a mixing step for mixing water-absorbing resin particles and additive particles, wherein rate of content of over cohesive particles, having a particle diameter of equal to or larger than 1.0 mm, in the additive particles, is equal to or smaller than 20% by weight.
2. A method for producing a water-absorbing resin composition, comprising a mixing step for mixing water-absorbing resin particles and additive particles, comprising a step for crushing or classifying the additive particles in advance, before the mixing step.
3. The method for producing according to claim 2, wherein the additive particles are crushed or classified so that rate of content of over cohesive particles, having a particle diameter of equal to or larger than 1.0 mm, in the additive particles, is equal to or smaller than 20% by weight.
4. The method for producing according to claim 2, wherein the additive particles are crushed by subjecting to passing through a screen mesh or a perforated plate.
5. The method for producing according to claim 2, wherein the additive particles are crushed by blowing airflow generated under pressure or by aspiration to the additive particles.
6. The method for producing according to claim 2, wherein the additive particles are crushed by stirring.
7. The method for producing according to claim 2, wherein the additive particles are crushed by using a crusher.
8. The method for producing according to claim 2, wherein the additive particles are crushed at the same time as conveyance of the additive particles.
9. A method for producing a water-absorbing resin composition, comprising a mixing step for mixing water-absorbing resin particles and additive particles, wherein a mixture of the water-absorbing resin particles and the additive particles is subjected to pneumatic transportation processing under a pressure of 0.1 to 10 MPa after mixing or at the same time as mixing of the water-absorbing resin particles and the additive particles.
10. A method for producing a water-absorbing resin composition, comprising a mixing step for mixing water-absorbing resin particles and additive particles, wherein a mixture of the water-absorbing resin particles and the additive particles is subjected to pneumatic transportation processing in plug flow after mixing or at the same time as mixing of the water-absorbing resin particles and the additive particles.
11. The method for producing according to claim 9, wherein the mixture of the water-absorbing resin particles and the additive particles is subjected to pneumatic transportation processing in a heated state.
12. The method for producing according to claim 9, wherein the pneumatic transportation processing is carried out just after mixing of the water-absorbing resin particles and the additive particles.
13. The method for producing according to claim 9, wherein the pneumatic transportation processing is carried out after mixing without stirring of the water-absorbing resin particles and the additive particles.
14. The method for producing according to claim 9, wherein time required for the pneumatic transportation processing is 0.1 to 20 minutes.
15. The method for producing according to claim 11, wherein the mixture to be subjected to the pneumatic transportation processing is heated or under heat-retention at 30 to 100° C.
16. The method for producing according to claim 1, wherein the additive particles are water-insoluble.
17. The method for producing according to claim 1, wherein the additive particles are cohesive fine particles.
18. The method for producing according to claim 17, wherein the cohesive fine particles are amorphous silica fine particles.
19. The method for producing according to claim 1, wherein centrifuge retention capacity of the water-absorbing resin to an aqueous solution of sodium chloride of 0.90% by weight is equal to or larger than 25 [g/g], and absorbency against pressure at 0.3 psi is equal to or larger than 10 [g/g].
20. A water-absorbing resin composition containing 100 parts by weight of water-absorbing resin particles and 0.01 to 1 part by weight of additive particles, wherein percent by weight of the additive particles, (X [%]), based on 100% by weight of the water-absorbing resin particles in the composition, and weight ratio of free additive particles, (Y), relative to the percent by weight, (X [%]), satisfy the following formula:
0.04 (x)0.1≦y<0.2 (x)0.5
21. The water-absorbing resin composition according to claim 20, wherein ratio of content of the additive particles in the composition is larger than 0.2% by weight.
22. The water-absorbing resin composition according to claim 20, wherein the additive particles are water-insoluble.
23. The water-absorbing resin composition according to claim 20, wherein the additive particles are cohesive fine particles.
24. The water-absorbing resin composition according to claim 23, wherein the cohesive fine particles are amorphous silica fine particles.
25. The water-absorbing resin composition according to claim 20, wherein centrifuge retention capacity of the water-absorbing resin particles to an aqueous solution of sodium chloride of 0.90% by weight is equal to or larger than 25 [g/g], and absorbency against pressure at 0.3 psi is equal to or larger than 10 [g/g].
Patent Application
20070225160
