A fiber-treating agent including the following components (A) to (C) and having a turbidity of 1,000 NTU or less, where a part or all of the components (A) and (B) are optionally a condensate formed from the components: (A): formaldehyde or a hydrate thereof, (B): a phenolic compound having an electron donating group on at least one of meta-positions and a hydrogen atom on at least one of ortho-positions and a para-position, where the electron donating group on the meta-position optionally forms, together with adjacent carbon atoms, a benzene ring optionally substituted with a hydroxy group, and (C): water.

An object of the present invention is to provide a modification method capable of affording animal hair having an anti-pilling property through simple treatment.

The present invention provides a method for modifying animal hair, including a reduction treatment step of treating animal hair with a reduction treatment liquid containing a reducing agent under a neutral or weakly alkaline condition, and an enzyme treatment step of treating the animal hair subjected to the reduction treatment with an enzyme treatment liquid containing a water-soluble protein and a transglutaminase.

A separator medium for electrochemical cells that contains at least one nonwoven sheet of polymeric fibers. The nonwoven sheet has a surface area of about 0.5 to about 1.5 m.sup.2/g and has a maximum pore size that is equal to or more than 2.5 times the mean flow pore size and more than 11 times the minimum pore size. The sheet may be sulfonated to a level of 0.67% and demonstrates superior tensile properties after sulfonation and relative to previously known separators.

A separator medium for electrochemical cells that contains at least one nonwoven sheet of polymeric fibers. The nonwoven sheet has a surface area of about 0.5 to about 1.5 m.sup.2/g and has a maximum pore size that is equal to or more than 2.5 times the mean flow pore size and more than 11 times the minimum pore size. The sheet may be sulfonated to a level of 0.67% and demonstrates superior tensile properties after sulfonation and relative to previously known separators.