Patent GB-600369-A (GB)
Title: Modifying leather by treatment with novel sulphonated polymeric materials
IPC: C14C9/00
Filed: 1945-09-21
Abstract: An acid emulsifying agent consists of a sulphonated polymeric material having a plurality of carboxyl groups attached to aliphatic carbon and a plurality of sulphonic groups attached to aromatic carbon.  The hydrogen in the acid groups may be replaced by a metal or ester group.  The materials are prepared by the sulphonation of polymers of the type described in Specification 530,643, [Group IV], especially the copolymer of maleic anhydride and styrene (see Group IV (a)).ALSO:Substances for use in the modification of leather (see Group VIII) consist of sulphonated polymeric materials having a plurality of carboxyl groups attached to aliphatic carbon and a plurality of sulphonic groups attached to aromatic carbon.  The hydrogen in the acid groups may be replaced by a metal or ester group.  The materials are prepared by the sulphonation of polymers of the type described in Specification 530,643, including copolymers of alpha-unsaturated carboxylic acids and their anhydrides, such as maleic anhydride, acrylic acid and methacrylic acid with polymerizable olefines containing an aromatic substituent, such as styrene, methyl styrene and indene.  The half ester formed from a higher alcohol, e.g. lauryl or stearyl alcohol, and a sulphonated heteropolymer of styrene and maleic anhydride is used in fat-liquoring leather.  In examples, a styrene-maleic anhydride polymer, prepared as in Specification 549,682, is sulphonated by suspending in ethylene dichloride, cooling to 0 DEG  C., and adding a mixture of chlorosulphonic acid and ethylene dichloride.  The ethylene dichloride is removed by distillation, or by filtering off and drying the product.  Aqueous solutions of the materials are used in bleaching chrome-tanned leather, e.g. calf skins, at a pH of 1.5 to 3.0.  The materials may also act as foaming agents, dye-levelling agents and mordants.ALSO:Substances for use in the modification of leather (see Group VIII) consist of sulphonated polymeric materials having a plurality of carboxyl groups attached to aliphatic carbon and a plurality of sulphonic groups attached to aromatic carbon.  The hydrogen in the acid groups may be replaced by a metal or ester group.  The materials are prepared by the sulphonation of polymers of the type described in Specification 530,643, including copolymers of alpha-unsaturated carboxylic acids and their anhydrides, such as maleic anhydride, polyacrylic acid, and polymethacrylic acid, with polyacrylic acid, and polymethacrylic acid, with polymerizable olefines containing an aromatic substituent, such as styrene, methyl styrene and indene.  The half ester formed from a higher alcohol, e.g. lauryl or stearyl alcohol, and a sulphonated heteropolymer of styrene and maleic anhydride is used in fat-liquoring leather.  In examples, a styrene - maleic anhydride polymer, prepared as in Specification 549,682, is sulphonated by suspending in ethylene dichloride, cooling to 0 DEG  C., and adding a mixture of chlorosulphonic acid and ethylene dichloride.  The ethylene dichloride is removed by distillation, or by filtering off and drying the product. Aqueous solutions of the materials are used in bleaching chrome-tanned leather, e.g. calf skins, at a pH of 1.5 to 3.0. The materials may also act as foaming agents, dye-levelling agents and mordants.