WATER DISPERSION FOR AQUEOUS SYSTEM ELECTRODE COMPOSITION

PROBLEM TO BE SOLVED: To provide a water dispersion which has a dispersing function and a viscosity-control function when preparing an aqueous system electrode composition, and the effect of keeping pH of the electrode composition low, and which can be preferably used for an aqueous system electrode composition.SOLUTION: The water dispersion comprises an alkaline soluble polymer used for an aqueous system electrode composition. The alkaline soluble polymer essentially has 20-60 mass% of a structural unit originating from ethylenic unsaturated carboxylic acid monomer and 40-80 mass% of a structural unit originating from ethylenic unsaturated carboxylic acid ester monomer to a total of 100 mass% of the structural units that the polymer has. Assuming a polymer density of 2 mass%, the water dispersion shows, at 25°C, a viscosity of 50 mPa s or less in the condition of pH below 5, and a viscosity of 100 mPa s or higher in the saturated condition of pH 8, and has a total light transmittance of 90-100% in the condition of pH 8.