GB864692A - Improvements in and relating to the production of artificial threads - Google Patents

Abstract

Fibres of an optically active form of poly-gamma-methyl glutamate are produced by polymerizing an optically active gamma-methyl glutamate N-carboxy anhydride in an organic liquid which is a solvent for the polypeptide formed, the polypeptide being composed of at least 90% by weight of units of the optically active glutamate ester, dry or wet spinning a solution of the polypeptide while it is still in the "solvated state" so that the polypeptide is in the alpha-configuration on extrusion, and stretching the resultant fibre while it is still in this configuration, thereby converting the polypeptide into the beta-configuration and orienting the fibre along its axis. The polypeptide may be a copolymer of the ester with up to 10% of one or more other N-carboxy anhydrides such as the anhydrides of leucine, phenylalanine, norleucine, isoleucine or gamma-benzyl-glutamate. The polypeptide may be a mixture of the optically active forms of poly-gamma-methyl-glutamate, provided that at least 90% by weight of the mixture consists of one optically active form only. The term "solvated state" is defined as meaning that the polypeptide is dissolved either in the solvent in which the polymerization was effected, or in a different solvent, the polymerization solvent having been removed and replaced by the other solvent, but the polypeptide not having been allowed to dry out before the spinning step. The polypeptide may alternatively be dissolved in a solvent, a part of which consists of the solvent in which the polymerization was effected. The spinning solution solvent may be a chlorinated aliphatic hydrocarbon, preferably containing not more than 4 carbon atoms and at least 2 chlorine atoms in the molecule, or it may be N, N-dimethyl formamide. The solvent may contain diluents such as dioxane, ethyl or methyl acetate, methyl propionate or acetone. When threads are formed by wet spinning the coagulant liquid must be a non-solvent for the polymer which is miscible with the spinning solvent. It is preferably miscible with water, and the coagulant liquid may then be removed from the thread immediately after leaving the bath by washing it with water. The stretching of the thread is preferably effected while it is wet with water. In an example, 9,8 parts of gamma-methyl-L-glutamate N-carboxy anhydride dissolved in 100 parts of a mixture of 80 volumes of methylene chloride and 20 volumes of dioxane are polymerized at ordinary temperature by the addition of 0,16 part of tri-n-butyl amine to form a 7,5% solution of a poly-gammamethyl-L-glutamate which is wet-spun into acetone containing about 5% by volume of water and less than 10% by volume of methylene chloride. The filaments thus formed are withdrawn from the coagulating bath, passed through a water bath, stretched 90% while still wet, and dried on a steam-heated godet. Examples are given also in which solutions of the polymer are dry-spun. The threads produced by the process of the invention are insoluble in chlorinated hydrocarbons, and fabrics woven from them have the appearance and crease-resistance of fabrics of natural silk and high safe ironing temperatures. Specifications 675,298, 675,299, 690,341 and 692,433 are referred to.