When regenerating cellulose material in an acidic spin bath containing zinc sulphate, disturbancies frequently occur due to the presence of clogging material. The origins of the clogging material are different. One and the most im- portant source are solid by-products, i. e. elementary sulphur and zinc sulphide, which are formed when the dis- solved xanthogenated celluloses are regenerated to cellulose and carbon disulphide. Other examples of clogging by- products are hemicelluloses and resins derived from the cellulosic raw material itself and transfered to the spin bath where they cause deposits. One method of reducing these disadvantages is to add cationic surface active compound to the spinning baths. Thus, in Japanese Patent No. 48006409 it is suggested to add N, N'-polyoxyethylene-N-long chain-alkyl alkylene-diamines and N, N', N''-polyoxyethylene-N-long chain- alkyl alkylene-triamines into the spin bath as dispersants for sulphur particles which cause blockages in spinning nozzles. The long-chai alkyl group contains from 10 to 20 carbon atoms. The number of oxyethylene groups are from 1 to 8 for each substitution position and their sum is from 2 to 10. However, these additives have a rather limited ability to disperse sulphur, especially when the amounts thereof is high.

In Japanese Patent Application No. 54101916 it is suggested to add polyoxyethylene alkyl mono-and diamide polyalkylene polyamines to further reduce the clogging of nozzles. Examples of the used polyalkylene polyamines are triethylene tetramine and tetraethylene pentamine. The number of carbon numbers in the fatty acids used for pre-

paring the said compound is preferably from 12 to 22, while the number of groups derived from ethylene oxide in the molecule is from 6 to 12. Although these polyamines have a good dispersing effect they have a serious drawback since they are not stable in hot acid solutions and are hydrolyzed at high temperature in the spin bath. Consequently, after some time their effect is essentially reduced.

The degradation of the additive can be compensated by addition of higher dosages of the additives. However in practice the resulting products of the hydrolysis, i. e. the fatty acids produced especially during reconditioning of the spin bath, enhances the clogging. Together with elementary sulphur and/or zinc sulphide and resins they form black particles, which are very difficult to disperse.

It has now been found that not only the disturbancies of clogging materials in the spin bath are essentially diminished but also the quality of the fibers formed in the spin bath is improved by using an alkoxylated polyamine sur- factant having the formula RNA+CnH2nNAtx-1A (I) where R represents a hydrogen or an alifatic group with 1-24 carbon atoms, each A represents a hydrogen, an alifatic group with 1-24 carbon atoms, or H (OCmH2m) y-groups, where m is a number from 2-3, and y is a number from 1 to 5, n is a number from 2-3, x is 4-8, with the proviso that the number of H (OCmH2m) y-groups are from 1 to x+l, and the total number of carbon atoms in the aliphatic groups is from 8 to 45, as a viscose spin bath additive. The alkoxylated polyamine sur- factant has an excellent anticlogging effect, since it is a good dispersant and prevent or reduce precipitation in the spin bath. In comparison with the diamines and triamines disclosed in JP 48006409 the anticlogging and dispersing effects are essentially improved. In addition it is very stable in comparison with the amide compound disclosed in JP Patent Application No. 54101916. Since the additive keeps the openings in the spinneret free from clogging materials, the filaments and films formed collect less solid particles,

whereby the discolouration is reduced and the fiber or film strenght improved. In addition the maintainance of the spin bath is also simplyfied. Since the alkoxylated polyamine surfactant has a high stability in ordinary working-up- processes of the spin bath, the spin bath solution can be recirculated after the removal of an excess of the by- products including sodium sulphate formed in the spin bath.

The amount of the alkoxylated polyamine surfactant in the spin bath may be varied within wide limits but is normally added in an amount of 0.5-5000 ppm, preferably from 2 to 1000 ppm, to a spin bath containing 5-15% by weight H2SO4, 15-30% by weight of Na2SO4 and 0-7% by weight of ZnSO4.

The alkoxylated polyamine surfactant with formula I preferably contains one or two aliphatic groups, R and A, with a total of 8 to 40 carbon atoms, preferably between 10 and 36 carbon atoms. Preferably R is a hydrocarbon group with 8-24 carbon atoms, and most preferably a hydrocarbon group with 10-22 carbon atoms, while m is 2 and the total number of OC2H4-units are from 4 to 30.

Most preferred alkoxylated polyamine surfactants of the formula I are those having the formula RNA-(C3H6NA)-x-1A(II) where R has the meaning mentioned in formula I, x is 4-6 and A is hydrogen or the group (C2H40) yHt where y has the meaning mentioned in formula I and the total number of C2H40-units is from 4 to 15. These additives are easy to produce and have excellent dispersing ability.

The present invention also relates to a process for regeneration of cellulose from a viscose solution, in which process the viscose solution is brought into contact with a spin bath containing from 0.5 to 5000 ppm of an alkoxylated polyamine surfactant according to formula I. Preferably the alkoxylated polyamine surfactant has the formula II. The spin bath has normally a temperature of from 40°C to 60°C and contains in addition to the alkoxylated polyamine sur- factant from 5 to 15% by weight of H2S04, from 15 to 30% by weight of Na2SO4 and from 0-7% by weight of ZnS04. The cellu-

lose regenerated may have the form of fibers or films or any other conventional shape.

The invention is further illustrated by the following examples.

Example 1.

Degradation kinetics of two spin bath additives were evaluated in a spin bath with the composition 9,5% H2SO4, 23% Na2SO4,0,4% ZnS04 and 67,1% H20 at different tempera- tures stated in the tables below.

One of the additives was an amide condensate of tetraethylene pentamine and a tallow fatty acid ethoxylated with 10 moles ethylene oxide per mol amide, hereinafter re- ferred to as Compound B. Compound B is a typical representa- tive of an additive in the Japanese Patent Application No.

54101916. The other additive was an N, N',N'',N'''-polyoxy- ethylene-N- (tallow alkyl) tetraamine with 7.5 moles oxyethy- lene per mole tetraamine. This additive is a typical repre- sentative of an alkoxylated polyamine surfactant according to this invention.

The content of Compound B and Compound 1 in the spin bath solutions were analyzed by using the dye Orange II.

This dye and the cationic surfactant were reacted and the complex formed was extracted into chloroform. Then the amount of the complex in the chloroform phase was spectro- fotometrically determined at a wave length of 488 nm.

The data obtained are presentated below in Tables 1 and 2.

The figures show the residual non-degraded amount of Compound B and Compound 1 in %.

Table 1. Content of Compound B, %

Time, h Temperature 220C 50-C 700C reflux 1001001000100 6 90 35780 24 90 I 75 60'20 48 90 65 50 15 Table 2. Content of Compound 1, % Time, h Temperatures 75°Creflux22°C50°C 1001001000100 6 100 100 100 100 24 100 100 100 100 48 100 100 100 100 From the results it is evident that the stability in the hot spin bath solution is much lower for the amide type of spin bath additive (Compound B) than for the additive according to the invention (Compound 1).

Examples 2-4.

Precipitation prevention and dispersing capacities of some spin bath additives were determined according to the following procedure.

21 ml of a solution containing 0.25 M Na2S2O3, 0.15 M Na2CS3 and 0.25 M Na2S was dropwise added during stirring into a polypropylene vessel containing 1 liter of a spin bath. The spin bath contained 10% by weight H2SO4,20% by weight Na2SO4,1% by weight ZnSO4, 69% by weight H20 and a dispersing additive from 0-25 ppm. Its temperature was 50°C.

The stirrer was made of glass with a propellar of platinum.

After the addition the transmittance of the bath was measur- ed after predetermined times in a spectrophotometer at the wave length of 450 nm in a glass cuvette. During the whole test the stirring was kept constant at 300 rpm. After 270

minutes the test was interrupted and the weight of the stirrer was measured in order to determine the amount of material precipitated on the stirrer.

The following dispersing additives were used.

Compound A.

A compound having the formula (EO) XH (EO) y H C18-alkyl-N-C3H6N (EO)zH where EO is ethyleneoxy and the sum of x, y and z is 10, in accordance with the amine compound disclosed in the Japanese Patent No. 48006409.

Compound B.

Same compound as in Example 1.

Compound C.

A compound having the formula <BR> <BR> <BR> <BR> (EO) XH (EO) WH (EO) y H<BR> <BR> <BR> <BR> <BR> <BR> <BR> Cle-alkyl-N-C3H6N-C3H6N (EO) z H where EO is ethyleneoxy and the sum of x, y, z and w is 10.

Compound 1.

Same compound as in Example 1.

Compound 2.

Same compound as Compound 1 but the number of oxyethylene units was 6 per mole tetraamine.

The tests performed and the results obtained are shown in Table 3 below.

Table 3.

%Time,Transmittance, min Com- - A AB C 121 pound AmOUn 5 25 5 5 5 10 25 5 t ppmppmppmppmppmppmppm 100100100100100100911001000100 30 57 71 67 39 59 84 33 80 60 52 41 48 25 42 36 21 36 49 120 47 38 42 32 35 30 19 15 35 270 45 41 30 36 35 26, 8 5 29 Dry weight of precipitation on Pt-stirrer, mg 80402123.20.00.00.03.5270182 It is evident that the spin bath additives in accordance with the present invention have an improved ability to disperse solid and colloidal particles and to prevent the precipitation thereof in comparison with the spin bath additive disclosed in the Japanese Patent No.

48006409 and Japanese Patent Application No. 54101916.