FI86080B - FOERFARANDE FOER BEHANDLING AV BISULFITPAPPERSMASSA. - Google Patents

Abstract

1. A method of treating a bisulphitic paper pulp having a high mean degree of polymerization of approximately 1,100, characterized in that, in order to give it the characteristics of a pulp for chemical purposes, there is caused to act upon the paper pulp an enzymatic preparation on a basis of fungic cellulases having a C1 activity and a Cx activity, a maximum activity in the pH range from 1.5 to 7.5, and at a temperature below 80 degrees C, the reaction medium being continually stirred the pH being maintained between 2 and 7 and the temperature below 80 degrees C during the action of the enzymatic preparation.

Description

1 86080

This invention relates to the production and use of pulps for the production of wood-derived cellulose for chemical use.

Wood is a mixture of different components, the most important of which are lignin, hemicelluloses and cellulose. Different types of cellulose pulps can be made from this naturally occurring raw material, depending on their lignin content. The composition of these pulps and the method of their preparation determine their use.

Thus, pulps for chemical use or Liu-pulps refer in particular to raw materials for the production of man-made textile fibers, films and films or varnishes.

Instead, the fibrous raw materials used in papermaking are mechanical pulp, which is simply finely ground wood in the manufacture of newsprint, or unbleached or bleached chemical pulp, such as pulp used in the manufacture of kraft paper.

In general, sulfite pulps or sulfate pulps can be prepared.

In the sulphite process, the wood is boiled with alkali or alkaline earth ·: * ·; libisulphite and sulfuric acid solution and the resulting pulps are used for sanitary, chemical or papermaking purposes.

The sulphite process is mainly used in the production of pulps for chemical use.

2,86080

But pulps intended for the production of man-made textile fibers, such as viscose fibers, must have special properties, in contrast to pulps for the production of sanitary products or paper: the cellulose they contain must be chemically very pure, the cellulose chains must have regular lengths and good reactivity.

In order to obtain these properties, all the other components of the cellulose contained in the wood must be removed. To this end, wood is usually subjected to advanced chemical treatments: these treatments are difficult to control and pollute the environment. In particular, a considerable dispersion of the lengths of the molecular chains is observed, as well as a decrease in the yield relative to the wood raw material due to the decomposition of the short molecular chains of the cellulose.

In particular, for the production of viscose fibers, the pulp should be characterized by a high cellulose content of 90-95% and an average degree of polymerization (DPm) of about 700.

The poor properties of the pulp have a significant effect on the properties of fibers made from such pulp: for example, a deterioration in mechanical strength and poorer filterability.

Furthermore, for this application, it is not possible to start from a papermaking pulp because its cellulose is not sufficiently pure. It is difficult to obtain a spinning solution such as is needed in the manufacture of man-made textile fibers, such as viscose fibers. The pulp is generally purified by delignification and its cellulosic fibers are suitably bleached, but their average degree of polymerization (DPm) is not similar to that of chemical pulps.

Il 3 86080

It is an object of the invention to provide an improvement, at least in part, on these two types of disadvantages: it can thus be applied to a pulp for chemical use to produce a spinable solution for forming textile man-made fibers such as viscose fibers as to bisulphite-type papermaking pulp.

In the case of the manufacture of man-made textile fibers, and in particular viscose fibers, from chemical pulp, it is an object of the invention to advantageously influence the various steps involved in the preparation of a spinning solution without altering the mechanical strength of the fibers obtained by conventional chemical treatments.

The process for producing viscose fibers from cellulose pulp for chemical use schematically involves dissolving the cellulose pulp, then regenerating or coagulating it into yarns so that the resulting yarns are suitable for use in the textile industry. The most important steps here are the preparation of alkali cellulose by contacting the cellulosic pulp with sodium (just after this step there is a maturation step in which oxidation causes the too long cellulose chains to break). The second main step is the conversion of viscose into yarn: the alkali cellulose is sulfurized with carbon disulphide, the resulting cellulose saxanthate is dissolved in a sodium solution; the resulting spun solution (viscose) is homogenized, deaerated, filtered and then spun through nozzles into a regeneration bath where the regenerated viscose yarn coagulates.

Usually, in this traditional formula, the ripening step is performed by dividing the pulp into fine particles by means of grinders, which are stored for several hours in silos. But there are several disadvantages associated with the procedures used, notably the storage issue due to the duration of the ripening reactions.

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It is an object of the invention to improve this conventional manufacturing formula.

It is an object of the invention to speed up the manufacturing process of the solution to be spun and thus of the regenerated yarns.

Another object of the invention is to reduce the hemicellulose content of the dissolving sodium as well as the amount of sulfur carbon required for the formation of cellulose xanthate by sulfurizing alkali cellulose.

To this end, the invention proposes a new process for the treatment of bisulfite paper pulp with a high average degree of polymerization, which process comprises administering to fungal cellulases having activity and activity Cx with a maximum activity in the pH range of 1.5 to 7.5 below 80 ° C. at room temperature, the reaction enzyme preparation acts on the paper pulp, whereby the reaction medium is continuously stirred at a pH of 2-7 and a temperature below 80 ° C during the action of the enzyme preparation.

In this application, the enzyme preparation acts on the cellulose in a known manner by hydrolyzing it and lowering its average degree of polymerization.

. . This feature of the invention is particularly advantageous because it provides paper pulp, such as bisulphite cellulose pulp, with average polymerization properties similar to those used for chemical purposes, by lowering the average degree of polymerization of the cellulose, and in which case the text can be made. such as viscose fibers, without the normally required degradative and environmentally polluting treatments.

The invention therefore relates to a process for the preparation of a spinning solution for forming textile man-made fibers from wood-based cellulose pulp, in which the pulp for chemical use is replaced by a bisulphite-cellulose pulp for papermaking, the enzyme preparation 5 7 and a temperature below 80 ° C during the action of the enzyme preparation.

In this case, a spinnable solution can be prepared from a cellulose pulp that is less chemically treated than conventional pulps used in the textile industry. Bisulfite cellulose pulps for papermaking are particularly preferred because they contain less degraded cellulosic fibers than pulps for chemical use. The yield of these pulps is much better than the amount of wood raw material and they are thus more economical.

The enzyme preparation used in the invention is cellulase-based, in particular fungal cellulase-based, which is known to consist of various ingredients and some of them have in particular the activities Ci and Cx. Activity Ci is the effect of cellobiohydrolase, which can be analyzed from highly pure cellulose with an ordered structure, which is mainly found in cotton fibers. This activity manifests itself as the formation of cellobiose. Activity Cx can be analyzed for modified cellulose, carboxymethylcellulose, and its amount can be measured as a decrease in the viscosity of carboxymethylcellulose or an increase in reducing terminals.

As with all methods using enzymes, a number of conditions must be controlled to make the method effective: thus, for example, temperature, pH, enzyme concentration, and duration of action can be determined to be advantageous for carrying out the invention.

According to a further feature of the invention, an enzyme preparation. . is used in a concentration of 0.05-2% and preferably 0.4-0.6%, based on the total weight of the dry cellulose pulp.

Other features and advantages of the invention will become apparent from the following description, followed by examples of embodiments related to Table 1. The essential features of the invention are set out in the appended claims.

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The examples carried out within the scope of the invention are explained with regard to certain parameters which more or less affect the efficiency of the method. The parameters considered are as follows: mixing method, mixing rate, temperature, pH, concentration of the buffer solution.

The mixing method is of particular importance in all industrial processes. It has been found that mixing, characterized by high rotational energy and the presence of high shear forces, promotes reproducibility of the results. In this sense, it is preferable to use a two-arm mixer.

The mixing rate should be sufficient to form the enzyme-substrate complex, but should not be too high, as the efficacy of the enzyme preparation may be impaired.

The activity of enzyme preparations is directly related to temperature. Therefore, all steps of the process in which the enzymes are used are performed in baths equipped with thermostats. In addition, by influencing the temperature, i.e., raising the temperature of the reaction medium to 100 ° C for 5 minutes, the enzyme reaction is stopped.

The effect of enzyme preparations is also strongly related to pH. Enzymes cannot withstand strong pH changes. Appropriate pH conditions must therefore be used.

One way to maintain the pH is to use a buffer solution. It has been found that the concentration of the buffer solution affects the activity of the enzyme. The preferred concentration of CH3 COONa / CH3 COOH in the buffer solution is 0.01-0.2 M, which is particularly suitable for the enzymes used according to the invention.

·.! Examples relate to pulps and papermakers for papermaking

Table 1 summarizes the values of the parameters involved in the preparation of rayon pulps or in the pulp treatment of Examples 1-4: pulp quality, pulp (P), amount of pulp relative to total weight of solution, quality of enzyme preparation, cellulase (C) or liver enzyme (M), amount of enzyme, reaction temperature (T ° C), mixing mode (H: spiral mixer), mixing speed (rpm), reaction time in hours (h) at the time of parameter measurement. Examples 1-4 have the average degree of polymerization.

Examples 1-4

Addition of Enzymes to Papermaking Pulp In these examples, enzymes are added to give the papermaking pulp the properties of a pulp for chemical use. The pulp used is a long-fiber bleached pulp prepared by a known bisulfite method. It has the following properties: high average degree of polymerization, about 1100, alpha-cellulose content about 88%. This pulp contains much less impurities, especially hemicellulose, than pulp for chemical use.

The enzyme preparation is allowed to act on this mass by selecting the temperature and pressure conditions corresponding to its maximum activity.

Different experiments were performed with different enzyme concentrations: 0.05%, 0.2% and 0.75%. The development of the average degree of polymerization (DPm) during the reaction was determined at these different concentrations. Indeed, an increasing decrease in the average degree of polymerization of the enzyme is observed. . with concentration, which manifests itself as a change in the properties of the mass in the desired direction.

The experiments were performed with cellulase, which was used for pulps used for chemical purposes, at the temperature and pH-8 86080 conditions best suited to the properties of this enzyme preparation.

The papermaking pulp treated in this way can be used in a viscose-making process, either by the classical chemical method or, preferably, by the enzyme method according to the invention.

table 1

Eg Mass% Enzyme% pH T Mixer RPM / ° DPm _ ° C _min._ 1 P 2 C 0.2 4 40 H 500 1 760 2 P 6 C 0.2 4 40 H 500 1 750 3 P 4 C 0.05 4 40 H 500 4 780 4 P 4 C 0.75 4 40 H 500 4 680 * · • · ·

Claims (6)

9 86080 A process for treating bisulphite paper pulp with a high average degree of polymerization, about 1100, characterized in that the purpose of obtaining the properties of a pulp chemically suitable for pulp is administered by a fungal cellulase-based enzyme preparation having activity and activity Cx at maximum pH 1, 5-7.5, at a temperature below 80 ° C, affects the pulp, whereby the reaction medium is continuously stirred and the pH is kept between 2 and 7 and the temperature below 80 ° C during the action of the enzyme preparation. Process according to Claim 1, characterized in that the enzyme preparation is added in a concentration of 0.05 to 2% and preferably 0.4 to 0.6% of the total dry weight of the cellulose pulp. Process according to Claim 1 or 2, characterized in that the enzyme preparation is based on Basidiomycetes Sp. Poria-derived cellulase. Process according to one of Claims 1 to 3, characterized in that the reaction medium is stirred. . with a torque having a high rotational energy and a shear; the forces are considerable. Process according to Claim 4, characterized in that the reaction medium is stirred with a two-lever stirrer. A method according to any one of claims 1 to 5,. : characterized in that the pH is 4-6 and the temperature is 40-50 ° C. 10 86 080