Search International and National Patent Collections
|1. (WO2018180864) WATER-ABSORBING RESIN|
|Applicants:||SUMITOMO SEIKA CHEMICALS CO., LTD.
Provided is a water-absorbing resin which is capable of giving an absorbent having improved gel-shape stability and which has excellent water-absorbing performance. The water-absorbing resin of the present invention is a polymer of a water-soluble, ethylenically unsaturated monomer, and has the following properties (1) and (2). (1) To have a disintegration amount at 20-fold swelling of 30 mass% or less. (2) To have a solubility in physiological saline solution of 25 mass% or less. (Determination method for disintegration amount at 20-fold swelling) Five grams of the water-absorbing resin are added to 100 g of physiological saline solution to allow the water-absorbing resin to absorb the physiological saline solution, thereby obtaining a gel. The obtained gel is divided approximately equally into five portions, and these portions are introduced respectively into cylindrical molds having a length of 3.6 cm and a radius of 2.8 cm and molded. The masses of the five molded cylindrical gels are measured. The heaviest and the lightest of the five gels are removed and the remaining three gels are used as samples. The mass Wa (g) of each sample is measured. Each weighed sample is placed on the uppermost screen of a combination of JIS standard screens having an opening size of 5.6 mm and a saucer in this order and shaken for 10 minutes using a Ro-Tap shaker (rotation speed, 290 rpm; number of taps, 165 rpm). The mass Wb (g) of the gel which has passed through the screens is measured. The disintegration amount of each sample is calculated using the following equation. Disintegration amount of sample (%) = (Wb (g))/(Wa (g))×100 The average of the disintegration amounts for the three samples is regarded as the disintegration amount at 20-fold swelling of the water-absorbing resin.