Patent ID: 9540501
Date: 2017-01-10
CPC Classifications: C08L,E21B

Claim:
1. A water swellable rubber composition comprising: (a) a non-water swellable base rubber, (b) a combination of (i) an ethylene oxide based hydrophilic elastomer having at least 65 mole % of ethylene oxide and having no crosslinkable curable functional group, and (ii) an ethylene oxide based hydrophilic elastomer having at least 65 mole % of ethylene oxide and a crosslinkable curable functional group, wherein the combination has in total less than 5 mole % of a crosslinkable curable functional group, and (c) a water swellable non-elastomeric material which is at least one selected from the group consisting of sodium acetate, sodium formate, and sodium acrylate, wherein the composition comprises 100 phr of the base rubber (a), 50-200 phr of the combination of ethylene oxide based hydrophilic elastomers (b), and 20-200 phr of the water-swellable non-elastomeric material (c).