GB835761A - Improvements in or relating to the production of regenerated cellulose filaments from viscose - Google Patents

Abstract

In the production of regenerated cellulose filaments from viscose, the viscose is prepared by xanthating alkali cellulose with at least 37% of carbon bisulphide, based on cellulose, and contains, per 100 grams, not more than 1 millimol. of an alkali-soluble monoamine modifier, and the coagulating bath contains up to 10% of sulphuric acid and at least 5% of zinc sulphate, the percentage of carbon disulphide used for xanthation being at least 4.9 times the percentage of sulphuric acid in the bath. The monoamine modifier is defined as a primary, secondary or tertiary aliphatic monoamine having at least 4 carbon atoms but containing no radical of more than eight carbon atoms and soluble in 6% aqueous sodium hydroxide to an extent of at least 0.1%. Preferred amines are those in which the amino nitrogen is attached to hydrocarbon groups, preferably alkyl groups, and/or to hydroxy-alkyl groups. A list of suitable amines is given, the specified amines including diethylamine, triethylamine, butylmonoethanolamine, cyclohexylamine and N-methylcyclohexylamine. The amount of amine added per 100 grams of viscose may be as little as 0.02 millimol. but is preferably 0.1 to 0.85 millimol. The viscose is preferably heated to 40 DEG C. or over prior to spinning and the spinning bath is preferably maintained at a temperature between 40 DEG and 80 DEG C. The bath preferably contains 4-10% of sulphuric acid, 5-25% of sodium sulphate and 5-15% of zinc sulphate. It may also contain ferrous sulphate, manganese sulphate, nickel sulphate or chromic sulphate. In an example, viscose prepared by xanthating alkali cellulose with 42% of carbon bisulphide (based on cellulose) and containing, per q00 grams, 0.6 millimol. of triethylamine, is extruded into a spinning bath maintained at about 63 DEG C. and containing 7.5% of sulphuric acid, 17.5% of sodium sulphate and 9.5% of zinc sulphate to form a yarn which is stretched 70-80% in the spinning bath and an additional 20% after leaving the bath. The process produces smooth-surfaced filaments of high skin/core ratio. Specifications 652,471, 652,746, 654,083, 741,727 and 835,762 are referred to.