Use of a binder comprising 2-cyanoethyl group-containing polymer for a separator of non-aqueous electrolyte battery , and process for preparing the separator

An object of the invention is to provide a binder for a separator, which can be comprised by a non-aqueous electrolyte battery with improved battery properties and heat resistance; a separator comprising the binder; and a non-aqueous electrolyte battery comprising the separator. More specifically, provided is a binder for a separator of a non-aqueous electrolyte battery, the separator comprising a 2-cyanoethyl group-containing polymer having bis-cyanoethyl ether content of 0.5% by weight or less as an impurity.