Water-absorbent resin and method of producing water-absorbent resin

a water-absorbent resin and water-absorbent resin technology, which is applied in the direction of bandages, chemistry apparatus and processes, other chemical processes, etc., can solve the problems of difficult to satisfy a balance between these properties, water-absorbent resin obtained by these methods does not necessarily satisfy those properties, and liquid is often blocked, so as to achieve the effect of reducing the amount of re-wet and improving the diffusibility of to-be-absorbed liquid

Inactive Publication Date: 2017-07-27
SUMITOMO SEIKA CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a water-absorbent resin that allows the liquid to be easily absorbed, reducing the amount of re-wet when used in an absorbent material.

Problems solved by technology

However, for example, since the water-retention capacity and the water-absorption rate are in a contradictory relationship with the water-absorption capacity under a load, it is difficult to satisfy a balance between these properties.
However, water-absorbent resins obtained by these methods do not necessarily satisfy those properties such as the high water-retention capacity, the high water-absorption capacity under a load and the better water-absorption rate as described above, and a room for improvement still remains.
Further, when a water-absorbent resin showing a relatively rapid water-absorption rate is used in an absorbent material comprising a water-absorbent resin, the water-absorbent resin may locally absorb a to-be-absorbed liquid around a feeding position of the to-be-absorbed liquid, and the liquid is often blocked because the water-absorbent resin becomes swollen and denser.
Moreover, in this case, since the diffusibility of the to-be-absorbed liquid into the absorbent material is prevented by the gelatinized water-absorbent resin, and the to-be-absorbed liquid may not be easily distributed throughout the absorbent material, the amount of re-wet of the to-be-absorbed liquid tends to be larger.

Method used

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  • Water-absorbent resin and method of producing water-absorbent resin
  • Water-absorbent resin and method of producing water-absorbent resin
  • Water-absorbent resin and method of producing water-absorbent resin

Examples

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examples

4. Example

[0084]Hereafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention shall not in any way be limited to the following Examples and the like.

[Evaluation Test of Water-Absorbent Resin]

[0085]Water-absorbent resins obtained from Examples 1, 2 and 3 and Comparative Examples 1 and 2 below were subjected to various tests described below for evaluation. In the followings, each evaluation test method will be described.

(1) Water-Retention Capacity of Physiological Saline

[0086]A cotton bag (cotton broadcloth No. 60, horizontal 100 mm×vertical 200 mm) into which 2.0 g of a water-absorbent resin was weighed out was placed into a 500 mL beaker. To the cotton bag containing the water-absorbent resin, 500g of 0.9 mass % aqueous sodium chloride (physiological saline) was poured in one portion so that lumps were not formed. The upper part of the cotton bag was then closed with a rubber band, and stood for a pr...

example 2

[0109]In Example 2, the same was performed as in Example 1 except that after the second-step polymerization, 236 g of water was removed from the system by refluxing n-heptane in azeotropic distillation of n-heptane and water. Thereby, obtained was 234.1 g of a water-absorbent resin having a different water-retention capacity from the water-absorbent resin obtained in Example 1. This water-absorbent resin was evaluated in accordance with the various test methods as described above.

[0110]Note that for the water-absorbent resin obtained, the mass proportion of particles from 150 to 850 μm relative to the whole proportion was 94 mass %, and the mass proportion of particles from 300 to 400 μm relative to the whole proportion was 36 mass %.

example 3

[0111]In Example 3, the same was performed as in Example 1 except that the addition amount of an internal-crosslinking agent ethylene glycol diglycidyl ether to be dissolved in the first-step aqueous monomer solution was 0.020 g (0.116 mmol), and after the second-step polymerization, 254 g of water was removed from the system by refluxing n-heptane in azeotropic distillation of n-heptane and water. Thereby, obtained was 232.9 g of a water-absorbent resin which differed from the water-absorbent resin obtained in Example 1 in that a different internal-crosslinking agent was used. This water-absorbent resin way was evaluated in accordance with the various test methods as described above.

[0112]Note that for the water-absorbent resin obtained, the mass proportion of particles from 150 to 850 μm relative to the whole proportion was 95 mass %, and the mass proportion of particles from 300 to 400 μm relative to the whole proportion was 33 mass %.

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Abstract

Provided is a water-absorbent resin that increases the diffusivity of a to-be-absorbed liquid and that makes it possible to effectively decrease the amount of re-wet. The water-absorbent resin is obtained by polymerizing a water-soluble ethylenicallyally unsaturated monomer under the presence of an internal-crosslinking agent, has the water-absorption capacity of physiological saline under a load of 4.14 kPa at 120 minutes passed from the start of water absorption of 20 ml / g or more, and exhibits the degree of swelling under a load at 30 minutes of 70% or less when the water-absorption capacity of physiological saline under a load of 4.14 kPa at 120 minutes from the start of water absorption is designated as the degree of swelling under a load of 100%.

Description

TECHNICAL FIELD[0001]The present invention relates to a water-absorbent resin and a method of producing the water-absorbent resin. More specifically, the present invention relates to a water-absorbent resin comprising an absorbent material suitably used for hygienic materials such as disposable diapers, sanitary napkins and incontinence pads, and also relates to a method of producing such the water-absorbent resin.[0002]BACKGROUND ART[0003]In recent years, water-absorbent resins have been widely used in the field of hygienic materials such as disposable diapers, sanitary napkins and incontinence pads.[0004]For water-absorbent resins as described above, crosslinked products of partially neutralized polymers of acrylic acid salt are preferred because they have many advantages, including the followings: they have better water absorption performance; their raw materials such as acrylic acid are easily and industrially available, and therefore they can be produced with stable quality and...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C08F8/14A61L15/60B01J20/26A61L15/24
CPCC08F8/14B01J20/267A61L15/60A61L15/24A61F13/49A61F13/53A61F13/15C08F2/32C08J3/245C08K5/14C08K5/23C08J2205/022
InventorHINAYAMA, TETSUHIROMURAKAMI, MASAHIROYABUGUCHI, HIROKIYOKOYAMA, HIDEKI
OwnerSUMITOMO SEIKA CHEM CO LTD