Patent GB-446757-A (GB)
Title: Process for the desulphurisation of viscose artificial silk
IPC: D01F11/02
Filed: 1934-11-05
Abstract: In a process for desulphurizing viscose artificial silk, the silk is desulphurized by a physical method which consists in treating it with an aqueous solution of a washing or wetting agent belonging to one of the following groups: acid esters of fatty alcohols and polybasic acids, e.g. phthalic acid esters; higher fatty amines and their derivatives, e.g. stearylamine, stearylpyridinium chloride or oxethyloleylamine; fatty amides of aromatic amino-sulphonic acids, e.g. laurylnaphthionic acid; alkylated and oxyalkylated aromatic and hydroaromatic sulphonic acids, e.g. benzylnaphthalene sulphonic acids, diisopropyl benzene sulphonic acid or dodecylnaphthalene sulphonic acids, protalbinic acid or lysalbinic acid; sulphonated fatty acids, e.g. sulphonated palmitic acid; condensation products of fatty acid glycerides with naphthalene sulphonic acids; chlolic acid, glycollic acid and naphthenic acid, their salts or derivatives; mineral oil sulphonates, abietine sulphonates; semi-ether of glycol and polyglycol with fatty alcohol; amides, anilides, alkylanilides and naphthalides of oxy-fatty acids such as ricinoleic acid; fatty acid ethanolamides or ethanolamides glycolated with ethylene oxide; esters of glycerine and polyglycerine or of glycols and polyglycols; or lecithin.  A concentration of 5--30 grams per litre and a temperature of 60--100 DEG  C. is employed.  The material may be in the form of a thread, a hank, spool or cake or small bands or foils may be desulphurized in this manner.  Preferably a wetting agent is used which may be left in the fibre to serve as a softening or preparing agent.  Oils or fats may be incorporated in the bath. Several sulphur removing agents may be employed together and with other substances such as hydrogen peroxide.  Two baths may be employed one after the other.  When treating viscose to which a substance which lowers the surface tension of aqueous solutions with respect to sulphur has been added, the temperature may be lowered to 20 DEG  C.  Such substances which may be added in proportions of 0,1--0,3 per cent are described in Specification 417,290.  In examples, hanks of viscose artificial silk are treated for \ba1/2\be--2 hours at 70--90 DEG  C., with a \ba1/2\be per cent solution of the sodium salt of mono-oleyl ester of phthalic acid at a pH value of 4,9--9,5 but preferably of 7, or in a two per cent solution of sodium diisopropyl-benzene-sulphonate at a pH value of 6,3--9; or undesulphurized silk is treated for 2 hours at 80 DEG  C. with a 1 per cent solution of an oxyethylamide of a higher fatty acid.  A 1,5 per cent solution of Laventin or an alkyl substituted naphthalene sulphonic acid containing terpene may be used.  In other examples hanks of viscose silk are treated first with a 2 per cent solution of a polyglycol ether such as oleylpolyglycol ether, and then with a similar bath containing 0,03 per cent of hydrogen peroxide at 80 DEG  C., or a viscose made from sulphite cellulose and containing 6,5 per cent cellulose, 6,5 per cent sodium hydroxide and either 0,25 per cent of bornyl xanthate, 0,3 per cent of turkey red oil or 0,2 per cent of sodium alkyl-naphthalene-sulphonate is spun in a bath containing 13 per cent sulphuric acid and 30 per cent sodium sulphate, washed, and treated with a 2 per cent solution of sodium diisopropyl-benzene sulphonate at 20 DEG  C. for 1 hour.