Patent GB-802332-A (GB)
Title: Twist-set yarns and method of preparing
Inventor: NOVAK LEO J
IPC: D06M15/11
Filed: 1955-11-14
Abstract: Dextran is obtained by treating a composition comprising sucrose, corn steep liquor, mono-basic potassium phosphate, manganous sulphate, sodium chloride and water at a pH of 6.5 to 7.5 and room temperature with bacteria Leuconostoc mesenteroides, of which several are specified, and according to the selection of which the resulting dextran may be water-soluble or water-insoluble.  The fermentation reduces the pH, which is raised again by adding calcium chloride, which aids precipitation of phosphates, Thereafter, dextran is precipitated by adding acetone or ethyl or iso-propyl alcohol.  A purer dextran may be obtained by adding an aliphatic alcohol at a pH of 2.5 to 4.5.  The dextran may be hydrolysed by means of an acid or enzymatically to yield low molecular weight products and either these or the unhydrolysed products may be esterified with acids containing from 8 to 18 carbon atoms, of which mention is made of caprylic, pelargonic, palmitic, margaric and stearic acid, or with a mixture of said acids or with the corresponding acyl chloride or mixture of such chlorides.  Reaction with the acid chlorides is effected in the presence of quinoline, pyridine or N-methyl morpholine and, to ensure uniform reaction, in the presence of a swelling agent, e.g. xylene, toluene or dioxane, at a temperature of 100 DEG  to 150 DEG  C., the ester being recovered by washing to remove the hydrochloride of the organic base.  The dextran may be reacted with the acid in the presence of an "impeller," e.g. monochloro - acetic - anhydride, and a catalyst, e.g. magnesium perchlorate, at 50 DEG  to 100 DEG  C. The reaction mass may be dissolved in a solvent and, by adding to a non-solvent for the ester, the latter may be precipitated.  The ester may contain from 1 to 3 acid radicals per anhydroglucopyranosidic unit.  Groups containing 1 to 5 carbon atoms, e.g. acyl, alkyl, carboxyl, alkyl and hydroxyalkyl, of which carboxymethyl and hydroxyethyl are specified, may also be introduced into the molecule.ALSO:Natural silk or artificial yarns are twisted and set in the twisted condition by a coating of an ester of dextran or a dextran conversion product containing a chemically bound radical derived from a saturated fatty acid of from 8 to 18 carbon atoms. The artificial yarns may be of nylon or regenerated cellulose and the modified dextran may be applied in aqueous emulsion or in solution in chloroform, carbon tetrachloride, benzene, toluene, xylene or a chlorofluoromethane.  The ester may be formed from caprylic, pelargonic, palmitic, margaric or stearic acid or the corresponding acyl chloride or from a mixture of such acids or chlorides and "native" dextran or a dextran hydrolysis product of lower molecular weight.  Other groups, e.g. acyl, alkyl, carboxyalkyl or or hydroxyalkyl radicals of 1 to 5 carbon atoms, may be introduced into the molecule.  Carboxymethyl and hydroxyethyl groups are specified. The twist set yarns may be fabricated by weaving or knitting and the coating may be removed with solvents or hot solutions of a wetting agent or sodium hydroxide to release the twist and provide a crepe fabric.