Patent ID: 8377595

Claim:
A gelling agent for a battery, which comprises granular carboxyl group-containing polymer particles having a median particle diameter of 100 to 800 μm and a bulk density of 0.30 g/ml or more, wherein the gelling agent has a gel turbidity of 200 ppm or less, a gel density of 1.37 g/ml or more in a gel, and a gelation time of 60 minutes or less upon preparing a gel, said gel is prepared by adding 2 parts by mass of the granular carboxyl group-containing polymer particles to 98 parts by mass of 40% by mass of an aqueous potassium hydroxide solution, and a carboxyl group-containing polymer particle for forming the granular carboxyl group-containing polymer particles is produced by polymerizing an α,β-unsaturated carboxylic acid-type compound in an inert solvent that dissolves the α,β-unsaturated carboxylic acid-type compound but does not dissolve a carboxyl group-containing polymer.