Patent GB-811444-A (GB)
Title: Improvements in or relating to sheet material comprising adhesively-bonded fibers
IPC: D04H1/58
Filed: 1955-09-15
Abstract: 811,444. Agglutinated fibrous sheet materials. DU PONT DE NEMOURS & CO., E.I. Sept. 15, 1955 [Oct. 1, 1954], No. 26502/55. Classes 96 and 140. A sheet material consists of a non-woven batt predominantly comprising polymeric linear terephthalate ester filaments bound together with the polymeric reaction product of a polyalkyleneether glycol, an organic diisocyanate and a chain-extending compound containing active hydrogen atoms. The filaments may be staple or continuous. The terephthalic ester is a highly polymerized linear ester of terephthalic acid and a glycol of the series HO(CH 2 ) n OH where n is a whole number within the range of 2 to 10 inclusive. The batt may be prepared by paper making or air-blowing techniques or on acarding machine or other web-forming apparatus. Fibres of nylon, polyactylonitrile, cotton, wool, glass and viscose rayon may be blended with the terephthalate fibres. The polyalkyleneether glycol is represented by the formula HO(RO) n H, where R is an alkylene radical and n is an integer greater than 1. Polyglycols containing diverse alkylene radicals may be used. Specified polyalkyleneether glycols are polypropyleneether, polyethyleneether, polybutyleneether, 1,2-polydimethyleneether and polydecamethyleneether glycols. Aromatic, aliphatic and cycloaliphatic di-isocyanates and combinations thereof may be used. Specified di-isocyanates are 2,4-tolylene, m-phenylene, 4-chloro-1,3-phenylene, 4,4<SP>1</SP>- biphenylene, 1,5-naphthylene, 1,4-tetramethylene, 1,6- hexamethylene, 1,10-decamethylene, 1-4 - cyclohexylene, 4,4<SP>1</SP> - methylene - bis - (cyclohexyl isocyanate) and 1,5-tetrahydronaphthylene diisocyanates. Dimers of the monomeric diisocyanates and di-(isocyanataryl) ureas, such as di-(3-isocyanato-4-methylphenyl) urea may be used. Specified chainextending compounds containing active hydrogen atoms are water, hydrogen sulphide and organic compounds containing active hydrogen atoms attached to two different atoms in the molecule. The batt of fibres may be brought into contact with the polymeric binder by impregnating the bath with a solution or dispersion of the binder, by mixing with the binder in particulate form or by use of a preformed film of the binder. When the binder is used as a dispersion, in particulate form or as a preformed film, heat and pressure are required to effect coalescence of the blader with the batt ; when used as a solution, heat and pressure may be omitted. Specified solvents are dimethyl formamide, tetrahydrofuran, methyl ethyl ketone, nitrobenzene, o-dichlorobenzene, tetrachloroethane, chloroform, thiophone, a mixture of tetrahydrofuran and benzene, pyridine, cyclohexanone, the diethyl ether of ethylene glycol and carbon tetrachloride. In examples, a batt of polyethylene terephthalate fibres is formed on a card, impregnated with a solution of a polytetramethylene ether glycol (toluene diisocyanate elastomer in dimethyl formamide and dried. In a further example, polyethylene terephthalate fibres are formed into a waterleaf which is dried and then impregnated with a solution in carbon tetrachloride of an elastomeric polymer prepared by reacting polytetramethyleneether glycol with 2,4-tolylene diisocyanate to form polymethane which itself is then reacted with water and further 2,4- tolylene di-isocyanate. In another example a batt, impregnated according to the invention is dried, buffed and then coated with a watervapour transmittable coating which may consist of a sprayed deposit from a mixture of an aqueous latex of a butadiene-acrylonitrile copolymer, a water-soluble phenol-aldehyde resin, and an aqueous solution of sodium polyacrylate. The product may be embossed while hot from drying. A laminated assembly may be formed by superposing on a batt of polyester fibres a film comprising di - (3 - isocyanato - 4 - methylphenyl) urea and the reaction product of a polyalkyleneether glycol, an organic diisocyanate and a chain-extending compound containing active hydrogen and subjecting the assembly to heat and pressure. Specifications 578,079, [Group IV], 695,567, [Group IV (a)], and U.S.A. Specification 2,451,915 are referred to.