ENCLOSED LEAD BATTERY-USE SEPARATOR AND ENCLOSED LEAD BATTERY

A separator for a valve regulated lead acid battery is composed mainly of fine glass fibers 1 and also contains inorganic powder 3, beaten natural pulp 2, and heat-weldable organic fibers 4. The heat-weldable organic fibers 4 have a fineness of 1.5d (deniers) or less and a fiber length of 1 mm or more, and the amount of the heat-weldable organic fibers is from 3% to 15% by weight. The separator is excellent in resistance against a short circuit between a positive electrode plate and a negative electrode plate of the battery such as an electrochemical short circuit, for example a short circuit due to lead penetration, and a mechanical short circuit. The separator is also excellent in folding endurance, in durability against repetition of folding, and in tearing strength, and allows easy formation of envelope-like separator, thus preventing active materials from being coming off at the sides thereof. The separator improves the power, the capacity, the stability, and the life duration of a valve regulated lead acid battery.