DE1045387B - Process for the production of viscose - Google Patents

Description

In the usual way of producing viscose, in which the pulp is soaked in sodium hydroxide solution and pressed and is then shredded, these operations are known to be followed by what is known as preliminary maturity the alkali cellulose from about 1 to 3 days. During this time in which the alkali cellulose im is generally exposed to the action of atmospheric oxygen at a slightly elevated temperature a depolymerization of the cellulose, which makes it possible after the xanthogenation of a viscose of To obtain the desired spinning viscosity with the usual cellulose content of about 8%. If you leave this Pre-ripening of the alkali cellulose results in an extraordinary amount when the usual cellulose content is set viscous solutions that cannot be transported through the usual pipelines with normal means, Pumps etc., especially do not allow them to be filtered.

The implementation of the pre-maturity requires the installation of large rooms and equipment, which the Can absorb alkali cellulose production for the necessary maturation period. This means a significant one Loss of dead capital. Attempts to pre-mature by adding chemicals to the alkali cellulose to accelerate, have so far not brought a satisfactory result, because the even distribution the chemicals within the alkali cellulose is difficult and the degradative effects of such agents even in the viscose or even in the finished thread makes it noticeable, so that a safe control dismantling in this way is associated with great difficulties in practice.

It has now been found that in the action of cellulose-degrading enzymes in the usual way Cellulose obtained through acidic or alkaline cooking is safer before being processed on viscose There is a way to achieve the desired degree of polymerization of the pulp in the viscose, so that the usual pre-maturity can be omitted. With this method it is possible to reduce the degree of degradation keep exactly within the desired limits. A pulp pretreated in this way can be quickly approved Process solutions of the usual concentration and deliver when spinning in the usual spinning belts Threads of excellent evenness, the properties of which are those obtained by the classical process manufactured viscose threads are in no way inferior. The depolymerization of cellulose by Enzymes are known per se, but this fact has not yet been exploited for the production of viscose.

The degradation of the cellulose with cellulose-splitting enzymes is expediently carried out according to the preceding one Milling or other mechanical or chemical pretreatment of the pulp, for example Process for the production of viscose

Applicant:

Phrix-Werke Aktiengesellschaft,
Hamburg 36, Stephansplatz 10

Dr. Fritz Opderbeck, Dipl.-Ing. Günther Trapp

and Dr. Günter Wörner, Okriftel / M.,

have been named as inventors

Alkalis or acids can be used. The action of the enzyme takes place advantageously at a somewhat elevated temperature, e.g. B. at about 30 ° C. Those cellulase preparations that are obtained from cultures of Aspergillus orycae or Aspergillus niger are particularly suitable for degradation. The treatment is best at a relatively low consistency, e.g. B. in Mahlholländer perform. The _pH value of the solution is in neutral or acidic region, for. B. at values between 3 and 6, held. Reductions in the Cuoxam viscosity of the cellulose, measured by the standard method, from 21.6 to 11.1 can be achieved within one hour.

For the production of viscose the fact that the cellulase proves to be particularly favorable preferred cleavage of the longer molecular chains takes place, so that a considerable standardization of the Degree of polymerization of the starting material is achieved. A decline in the exploitation of pulp occurs at the The cellulase solutions do not have any effect.

A peculiarity of the enzymatically degraded cellulose is that it becomes keratinized when it dries. It is therefore advisable to process the degraded cellulose with a moist cloth. He lets himself under Keeping its reactivity in the dry state when the water is suitable organic liquids are displaced beforehand.

The use of enzymatically degraded cellulose for the production of viscose offers particular advantages, if the viscose is obtained by the so-called one-pot process, in which the one to be dissolved Pulp is converted into finished viscose in a single reaction vessel. The implementation of the One-pot process has so far failed in practice because it has not yet been possible to break down the cellulose

809 697/54: 8

can be carried out loosely to the desired degree within technically useful short times. The inclusion of the normal pre-ripening for the alkali cellulose is therefore in the one-pot process not possible because the reaction vessel is not used for days for the intended depolymerization of the Can block cellulose. The addition of chemicals which accelerate the depolymerization, e.g. B. Sulphides, to quickly bring about the desired degree of degradation fails, apart from the prices of such chemicals, the difficulty of precisely metering the effect of the same and always one to maintain uniform viscose quality. The use therefore proves to be particularly suitable for the one-pot process Cellulose that has previously been enzymatically degraded is particularly advantageous.

The following examples are intended to explain the process according to the invention in more detail.

400 kg of air-dry beech textile pulp are made in the Steinholländer at room temperature Ground for 7V2 hours until the grind is about 67 ° Schopper-Riegler is. The ground substance is mixed with an enzyme solution in a mixer, which has been obtained as follows:

A strain of Aspergillus orycae is grown on a culture medium consisting of wheat bran and cellulose grown in the usual way until a dense lawn of molds has formed. Then it will be this culture in a suitable mixer for about two and a half hours with ten times the amount of tap water (calculated on the dry nutrient medium) intensively processed and then 13 cbm from it by filtration Extract obtained.

The diastatic power of the enzyme solution, which also leads to a certain conclusion about the cellulose-splitting Activity Permits is 35.2. The consistency of the material mixed with the mushroom extract in the mixer is 3 ° / o pulp. The reaction temperature is 22 ° C.

After a reaction time of IOV is 2 hours For example, the viscosity of the pulp, which was originally 22 Cp, has dropped to 13.7 Cp. the The final viscosity of the degraded pulp can be determined by varying the time and strength of the enzyme solution Adjust to the desired height.

The pulp is now drawn out through a wire section or a cell filter to a dry content dewatered by around 4OVo and fed to the viscose production.

This enzymatically degraded cellulose is now for comparison purposes once after the classic Viscose process and the other time processed according to the so-called one-pot process on viscose, which is then spun into threads.

a) One-pot process

The enzymatically degraded pulp was still moist in the kneader along with its water content appropriately reinforced immersion liquor kneaded, sulfided with 38% carbon disulfide for 40 minutes and solved. The Cuoxam viscosity of the starting pulp was 6.5 cps. Analysis of the finished viscose (I) resulted in the following values:

Viscose analysis, ° / o
NaOH [cellulose [S. 8.12 2.41 Ball drop
in
Seconds Maturity,
⁰ SR Filter value
Rw 6.78 114 12.2 145/180

Twelve spinning attempts were made each with changing the bath length and the draw ratio and the spinning speed. The data of the experiments were in each case in a narrow range Area together. For comparison, a normal air-ripened and according to the norms for Determination of the filter value of dissolved similar beech textile pulp (Bu-TZ) spun (II).

Mean values

description

Sulphiding time Tear strength, g / den
dry I wet

Strain, %
dry I wet

Relative
Wet strength, ° / o

(II) Bu-TZ standard

(I) enzymatically degraded

2V ₂ hours 40 minutes 2.16
2.35

1.42
1.52

15.5
15.2

16.6
16.2

65
64

Optimal values

description

Sulphiding time Tear strength, g / den
dry wet

Strain, %
dry wet

Relative
Wet strength, ° / o

(II) Bu-TZ standard

(I) enzymatically degraded

2V ₂ hours 40 minutes 2.30
2.56

1.58
1.56

16.6
15.3

17.5
16.0

71
67

The fiber data of the enzymatically degraded cellulose after 40 min. Xanthation time in comparison to those obtained from pulp processed after conventional pre-ripening and normal viscose production Surprisingly, fiber data are clearly superior, especially with regard to strength. This is Particularly noteworthy because with this method of working in the one-pot process, the Lye and, accordingly, no release of hemicellulose has taken place.

b) Usual mash alkalization with pressing

The enzymatically degraded pulp was, as usual, with a corresponding excess of lye mashed and pressed after an hour of immersion. A compression factor of 3.35 was used here

achieved. The sulfidation took place without prior alkali cellulose maturity, as above, for 40 minutes 38% carbon disulfide. It happened just like the subsequent dissolution of the viscose in the kneader. There were again twelve spinning attempts with different bath lengths, different draw ratios and different ones Spinning speed carried out. The results were also in a narrow range together. They are summarized in the following table:

Labelling Tear strength, g / den
dry | wet 1.58 Elongation, ° / o
dry [ wet Relative
Wet strength,% middle 2.36 1.73 16.2 16.2 67 Optimal.. 2.48 16.4 16.1 73

Here, too, it can be seen that if the elongation is satisfactory, the strength coefficients compared to the normal, pulp with alkaline degradation in the air are higher. The relative wet strength has also decreased by a few Percent increased. The filterability of the on the new Viscose obtained away is very cheap.

In summary, these experiments show that on the way of the enzymatic degradation of the Pulp a better quality thread can be achieved than in the normal way.

The degree of polymerization of the finished thread is about 385. The determination of the DP with the aid of the Cuoxam method shows that there is no significant further reduction in the degree of polymerization during processing he follows.

Claims (2)

Patent claims: 1. A method for the production of viscose, characterized in that a in the usual way through acidic or alkaline cooking of cellulose! Raw material obtained pulp, optionally after grinding or other mechanical or chemical treatment, the Exposed to the action of cellulose-degrading enzymes and then in a manner known per se, but without pre-ripening, is processed on viscose. 2. The method according to claim 1, characterized in that the processing to viscose after so-called one-pot process is carried out. Considered publications:
French patent specification No. 886 806. © 809 697/54 * 11th SS