Abstract: 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 1.5 d (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.

Abstract: A sheet-like separator has an electrolyte dripping speed of 100 mm/hr or less, wherein the values of repellent force on the pouring repellent force curve of pouring of dilute sulfuric acid shown in FIG. 1 are the following:______________________________________ if point S = P kg/dm.sup.2, point B .gtoreq. 0.55P kg/dm.sup.2 point C .gtoreq. 0.40P kg/dm.sup.2 ______________________________________A valve regulated lead acid battery employs the separator.

Abstract: A separator in which a flowing rate of an electrolyte is less than 100 mm/hr and a sealed lead acid battery using the separator.

Abstract: A separator substantially comprising only alkali-containing glass fibers with an average fiber diameter of less than 2 .mu.m, and having an electrolyte dripping speed of lower than 80 mm/hr and a content of sulfer S at the surface of the glass fibers of less than 0.02% by weight, as well as a sealed lead acid battery using such a separator.