JPH0965890A - Production of cellulose derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a cellulose derivative for thickeners, binders, stabilizers, etc., by treating pulp with an enzyme such as the enzyme capable of hydrolyzing β-1,4 glycoside bonds before chemically modifying the pulp, suppressing generation of microgels and improving filterability. SOLUTION: This production of a cellulose derivative for thickeners, binders, stabilizers, suspensions, etc., is to prepare a slurry from pulp with an acetic acid buffer having pH6, add an enzyme such as xylanase which is the enzyme capable of hydrolyzing β-1, 4-glycoside bonds and obtained from Bacillus sp. SD 902 (FERM-P-13356), treat the pulp slurry for 3 hours with agitating at 60 deg.C, feltering and dehydrating the pulp through a Buchner funnel and obtain the enzyme-treated pulp, add the enzyme-treated pulp to 88% isopropanol to prepare a slurry, add sodium hydroxide to bring to alkali cellulose, carry out chemical modifications such as methyl etherification, hydroxypropyl etherification, carboxymethyl etherification, etc., by adding chlorinated compounds and obtain the objective compound derivative.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a cellulose derivative. More specifically, it relates to a method for producing a cellulose derivative using cellulose treated with an enzyme.

[0002]

2. Description of the Related Art Cellulose ether is one of the cellulose derivatives, but methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), carboxymethyl cellulose ( Cellulose ethers such as CMC) are non-caloric, odorless, tasteless, water-soluble or water-suspendable white polymers. Therefore, thickeners, binders, stabilizers,
It is widely used as a suspending agent in the fields of food, medicine, cosmetics, paper and textiles.

Recently, as new applications of these cellulose ethers have been developed, there has been a demand for cellulose ethers having high performance depending on the applications. For example, it has excellent salt water resistance and corrosion resistance, and has a small amount of microgel. The term "microgel" as used herein refers to a cellulose ether which is not completely solubilized in a solvent but is in a semi-dissolved gel state due to insufficient etherification of cellulose.

Conventionally, cellulose ether is prepared by immersing lignocellulose such as wood pulp or linter pulp in a high-concentration alkaline solution to form alkali cellulose, and then using a suitable etherifying agent (eg, methyl chloride, ethyl chloride, ethylene oxide, propylene oxide). , Monochloroacetic acid, etc.)
The method of manufacturing by making the act on has been taken.

The cellulose ether produced by this method is strongly affected by the degree of substitution (etherification degree) and the distribution of substituents, and therefore, it cannot always obtain satisfactory properties depending on the application. For example, low-substituted cellulose ethers have poor solubility in solvents due to their non-uniform etherification. Further, a semi-dissolved gel-like substance called a microgel is liable to be generated, which is not only a preferable characteristic in terms of sensory (visual and tactile) but also causes deterioration of filterability of the solution.

On the other hand, a method of treating pulp with an enzyme has also been studied. As the enzyme, cellulase, xylanase, etc. are used. For example, in 1986, Viikari et al. Proceedings of the Symposium on Biotechnolog that the amount of chemicals used in the subsequent bleaching process can be reduced by applying an enzyme treatment to the pretreatment of pulp bleaching.
y in the Pulp and Paper Industry, 3rd Internationa
l Report at the conference.

Further, in Japanese Patent Laid-Open No. 2-245001, C
A method of reacting MC with cellulase to produce a hydrolyzate thereof is described. However, with this method
Since C is the form of enzymatic treatment of etherified pulp, many microgels are formed at the time of etherification. Therefore, in order to remove the microgel, it is necessary to use a large amount of enzyme, which causes a problem that the yield of the desired hydrolyzate is significantly reduced. On the other hand, if the yield of the hydrolyzate is emphasized, it is necessary to reduce the amount of enzyme used, and therefore, there is a problem that the enzymatic treatment of the microgel portion becomes insufficient and the microgel remains. The hydrolyzate obtained by this method is the original CMC.
Since the viscosity is remarkably reduced as compared with, it is inconvenient when used as a thickener or a binder. Therefore, it is an object of the present invention to provide a cellulose derivative in which generation of microgel is suppressed in the process of producing a cellulose derivative from pulp and filterability is improved.

[0008]

As a result of intensive studies to solve the above problems, the present inventors have found that an enzyme, especially Bacillus sp. By treating with the enzyme prepared from the culture solution of SD902, it was possible to improve the filterability of the cellulose derivative, to suppress the generation of microgel as much as possible or to suppress the intramolecular substitution distribution, which was difficult to be improved by the conventional method for producing the cellulose derivative. The inventors have found that they are homogenized and increase the water solubility of the cellulose derivative, and have completed the present invention.

That is, the present invention provides the following. 1) A method for producing a cellulose derivative, which comprises treating an pulp with an enzyme before chemically modifying the pulp. 2) The method for producing a cellulose derivative according to 1) above, wherein at least one of the enzymes used is an enzyme that hydrolyzes a β-1,4 glycoside bond. 3) The method for producing a cellulose derivative according to 1) above, wherein at least one of the enzymes used is hemicellulase. 4) The method for producing a cellulose derivative according to 1) above, wherein at least one of the enzymes used is xylanase. 5) At least one of the enzymes used is Bacillus sp.
The method for producing a cellulose derivative described in 1) above, which is a xylanase obtainable from SD902.

6) The method for producing a cellulose derivative described in 1) to 5) above, wherein the chemical modification is etherification. 7) The method for producing a cellulose derivative according to 1) to 5) above, wherein the chemical modification is methyl etherification, ethyl etherification, hydroxyethyl etherification, hydroxypropyl etherification, or carboxymethyl etherification. Hereinafter, the present invention will be described in detail.

The pulp used in the present invention is a pulp derived from softwood, hardwood or non-wood which has been cooked or bleached. The non-wood pulp referred to here is mulberry, san tsubaki,
Bast fiber plants such as abaca and kenaf, straw, sugar cane,
Pulp produced from hard fiber plants such as bagasse. In addition, cellulose derivatives having a low degree of chemical modification such as etherification and regenerated cellulose can be used as the pulp in the present invention.

The enzyme used in the present invention may be a single enzyme or a plurality of enzymes, at least one of which is β-.
An enzyme that hydrolyzes 1,4 glycoside bonds is preferable, and examples thereof include cellulase and hemicellulase.
More preferably xylanase, and even more preferably Bacillus sp. It is an enzyme derived from SD902. Bacillus sp. SD902 is accession number FERM P-1335
6 was deposited at the Institute of Biotechnology, Institute of Biotechnology, and then transferred to the international deposit, and the deposit number is FERMBP-
4508 is added. This strain was designated as JP-A-6-26.
Cultured according to the method described in 1750, enzyme (hereinafter,
(Abbreviated as SDX enzyme) can be prepared. The enzyme used does not have to be a pure enzyme, and may be a culture supernatant obtained by removing the enzyme-producing bacterium by centrifugation or the like, or an enzyme composition extracted from the bacterium.

The enzyme activity is determined by using xylan as a substrate and pH.
It can be represented by measuring the reducing sugar produced under the reaction conditions of 7,50 ° C. by the 3,5-dinitrosalicylic acid method. Note that 1 U is defined as the amount of enzyme that produces 1 μmol of xylose per minute. The enzyme treatment condition of the pulp used in the present invention is not particularly limited as long as the pH, temperature and time are set within a range in which the enzyme used is active, but it can be performed, for example, under the following conditions. . The treatment temperature is 20 to 90 ° C., preferably 40 to 80 ° C., the treatment time is 15 minutes to 24 hours, preferably 30 minutes to 5 hours, and the treatment pH is 3 to 9, preferably 4 to 8. The amount of enzyme added is
1-1000 U / g (versus dry pulp) Preferably 2-2
It is 50 U / g (versus dry pulp). Here, when the amount of enzyme added is less than 1 U / g, the treatment effect is poor, and 1000 U / g
When the amount exceeds g, the yield of pulp is reduced, and therefore the amount of enzyme added is not preferable.

The pulp concentration may be such that stirring and mixing are sufficient, but it is preferably 20% by weight or less. The chemical modification after the enzyme treatment in the present invention is preferably etherification, more preferably alkyl etherification, hydroxyalkyl etherification, or carboxyalkyl etherification, and even more preferably methyl etherification, ethyl etherification, hydroxy. Ethyl etherification, hydroxypropylation, or carboxymethyl etherification.

For the chemical modification of the pulp after the enzymatic treatment, any known method used in the chemical modification of pulp can be used. For example, pulp to CMC, MC, E
In the case of producing C, HEC, HPC, etc., there are two methods, a water medium method using an aqueous medium as a reaction solvent and a solvent method using an organic solvate.
It can be manufactured by a method roughly classified into two types. Taking CMC as an example, for the water medium method, the Alcer method in which the sodium monochloroacetate powder is added while crushing and stirring the pulp immersed in the sodium hydroxide solution, and the sodium hydroxide in which the pulp immersed in the aqueous sodium monochloroacetate solution is crushed and stirred is used. There is a monochrome method of adding. On the other hand, in the solvent method, a 6-fold method using a mixed solution of ethanol and benzene and 2
A 30-fold method with an aqueous propanol solution can be used. In addition, as a method of chemical modification other than the chemical method,
Enzymatic modification methods can be used.

[0016]

EXAMPLES The present invention will now be described in more detail with reference to examples based on experiments, but the present invention is not limited to these examples. In addition, the% described in the examples
Are all by weight.

Example 1 Commercially available bleached pulp (trade name "ARAUCO") was made into a 5% slurry with an acetate buffer of pH 6, and SDX enzyme was added to 5%.
Add 0 U / g (vs. absolute dry pulp). After treating the pulp slurry with stirring at 60 ° C. for 3 hours, the pulp is filtered and dehydrated on a Buchner funnel. The obtained enzyme-treated pulp was treated as CMC according to the carboxymethyl etherification (CMization) method shown below, and enzyme-untreated C
Characteristic comparison with MC was performed.

The characteristics of CMC were measured by the following methods.・ Method of making pulp CM A mixture of 88% isopropanol (30 times the weight of pulp) and a slurry was added to 1.8 mol of caustic soda per glucose group to give alkali cellulose, and then 0.8 mol of monochloroacetic acid was added. The reaction is carried out at 70-80 ° C for 2.5 hours. After completion of the reaction, filtration on a Buchner funnel and washing and filtration with a 75-80% methanol aqueous solution were repeated several times and then dried to obtain purified CMC.

Filtration rate: 200% CMC aqueous solution of 0.5% concentration, which was thermostatted at 20 ° C.
It was passed through a mesh sieve and the amount filtered in 5 minutes was measured with a graduated cylinder. -Viscosity The CMC aqueous solution of 2% concentration which was thermostatted at 20 degreeC was used, and it measured with the single cylinder type rotational viscometer.・ Microgel amount 200% of 0.5% CMC aqueous solution which was thermostatted at 20 ℃
Sift through a mesh screen and remove the wet weight of the remaining gel by C
Expressed as% by weight with respect to MC.

[0020]

[Table 1]

Example 2 The pulp treated by the enzyme treatment method shown in Example 1 was used as CMC by the Alcer method shown below, and the characteristics were compared with enzyme-untreated CMC.・ Arcel method Pulp is dipped in an 18% sodium hydroxide aqueous solution to
After 2 hours, press to remove excess sodium hydroxide,
Make three times as much alkali cellulose as the weight of pulp. While the alkali cellulose is transferred to a crusher and crushed and stirred, 1.2 to the pulp (anhydroglucose unit)
Add 2.0 moles sodium monochloroacetic acid powder. Crushing and stirring are continued for several hours while the temperature of the system is kept at 10 ° C. or lower to sufficiently infiltrate sodium monochloroacetate. After that, the crushed material is transferred to a reactor and stirred while stirring.
Hold at ~ 80 ° C for about 2 hours to obtain CMC. Washing and filtering with a 75-80% methanol aqueous solution was repeated several times and then dried to obtain purified CMC.

[0022]

[Table 2]

Example 3 A commercially available bleached pulp (trade name "ARAUCO") was made into a 15% slurry with a pH 8 phosphate buffer solution, and SDX enzyme was added thereto so as to give 100 U / g (versus dry pulp). To do. The pulp slurry is treated with an enzyme while stirring at 70 ° C. for 5 hours, and then the pulp is filtered and dehydrated on a Buchner funnel. The obtained enzyme-treated pulp was converted to methyl cellulose by the methyl etherification method shown below. As a control, enzyme-untreated pulp was methyl etherified and its characteristics were compared with enzyme-treated methyl cellulose.

Methyl etherification method: Pulp is dipped in caustic soda solution having a concentration of about 50% and then squeezed to obtain alkali cellulose having caustic soda and water in almost the same amount as cellulose. To this is added slightly more than equivalent amount of methyl chloride and the reaction is carried out in an autoclave at 95-100 ° C. After completion of the reaction, the product is washed with hot water on a Buchner funnel and dried to obtain purified methyl cellulose.

[0025]

[Table 3]

[0026]

Industrial Applicability According to the method for producing a cellulose derivative of the present invention, it is possible to obtain a cellulose derivative having improved filterability and suppressed formation of microgels as compared with the conventional one, and a thickener, a stabilizer, It can be effectively used as a suspending agent. Further, depending on the enzyme used, the above properties can be improved without lowering the viscosity, which is particularly useful.

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Claims (7)

[Claims] 1. A method for producing a cellulose derivative, which comprises subjecting a pulp to an enzymatic treatment before chemically modifying the pulp. 2. At least one of the enzymes used is β-
The method for producing a cellulose derivative according to claim 1, which is an enzyme that hydrolyzes 1,4 glycoside bonds. 3. The method for producing a cellulose derivative according to claim 1, wherein at least one of the enzymes used is hemicellulase. 4. The method for producing a cellulose derivative according to claim 1, wherein at least one of the enzymes used is xylanase. 5. At least one of the enzymes used is Bacillus sp. The method for producing a cellulose derivative according to claim 1, which is a xylanase obtainable from SD902. 6. The method according to claim 1, wherein the chemical modification is etherification.
5. The method for producing a cellulose derivative according to item 5. 7. The method for producing a cellulose derivative according to claim 1, wherein the chemical modification is methyl etherification, ethyl etherification, hydroxyethyl etherification, hydroxypropyl etherification, or carboxymethyl etherification.