Filters consisting of filter paper or paper-type nonwoven material

摘要

Filters and methods for producing filter paper or paper-like nonwoven materially consisting partially or wholly of fibrous cellulose containing material. The filters provided are characterized by high filtration capacity and are capable of absorbing and binding undesirable foreign and attendant substances in the filter medium. The cellulose containing material of the is at least partially carbamided with urea and phosphorylated with phosphoric acid or ammonium phosphate until a nitrogen content in the form of carbamide groups of 1 to 4% and a phosphorous content of 3 to 8% are reached.