To obtain a resin composition having excellent heat resistance by incorporating at least one electrolyte such as sodium carbonate or sodium hydrogencarbonate with a water-absorbing resin.
This composition is obtained by mixing 100 pts.wt. water- absorbing resin with 0.25-0.52 pt. wt. at least one electrolyte such as sodium carbonate or sodium hydrogen carbonate. A specified amount of each of sodium carbonate, sodium hydrogencarbonate, sodium benzoate sodium chloride sodium bromide and sodium dihydrogenphosphate is dissolved in water to form 300 cc of an aqueous solution having a water absorption rate of 120. Next, about 0.5 g of a water-absorbing resin is added to each solution, the resultant mixture is left standing at a high temperature (90°C) for 220 hr. The resin is filtered off and is measured on its water absorption rate. The results show that the water absorption rate for the sodium carbonate solution or the sodium hydrogen carbonate solution is much lower than those for the other solutions. The reason for this is presumably that the improved durability and consequent retarded deterioration of the water-absorbing resin inhibits an increase in a water absorption rate.
HAYASHI MINORU
SAKAI MAKOTO
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