JPS5917121B2 - Method for producing cellulose powder with high crystallinity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cellulose powder with a high degree of crystallinity.

Cellulose powder with a high degree of crystallinity (hereinafter simply referred to as crystalline cellulose) is widely used in the pharmaceutical field, food field, and various other industrial fields.

Conventionally, crystalline cellulose is obtained by hydrolyzing a cellulosic material with a mineral acid (e.g., hydrochloric acid or sulfuric acid) or an alkali (e.g., sodium hydroxide) to remove the amorphous regions of cellulose in the raw material. It is manufactured by mechanically crushing the crystalline region.
However, in the above-mentioned hydrolysis method using mineral acids or alkalis, coloration occurs due to excessively decomposed products due to uneven hydrolysis of the raw material, and the average degree of polymerization of cellulose due to hydrolysis increases. In addition, there are other problems such as restrictions on equipment and its materials due to the use of acids and alkalis at high temperatures.

The present invention was made in order to solve the problems in the conventional methods as described above, and it is an advantageous method to produce crystalline cellulose of good quality without coloring or decreasing the average degree of polymerization using a simple device. The purpose is to provide a method that can produce

The present inventor has come to realize the present invention based on the knowledge that cellulose with a high degree of crystallinity can be obtained by removing the solubilized material produced by treating cellulose or cellulosic substances with cellulase.

The present invention will be explained in detail below. The present invention involves treating cellulose or cellulosic substances with cellulase, separating the treated product into a solid-liquid fraction, removing the solubilized portion, and mechanically crushing the resulting cellulose solid content to powder it. It is characterized by

The micelle structure consisting of cellulose molecules consists of microcrystals of cellulose molecules and a non-crystalline region between them. Therefore, this amorphous region can be removed without damaging the microcrystalline portion of the cellulose molecules. This is essential for the production of crystalline cellulose.

According to the invention, the amorphous regions of cellulose can advantageously be removed by using cellulases. In the present invention, as raw materials for crystalline cellulose, wood pulp, bamboo pulp, esparto pulp, bagasse pulp, various types of pulp such as linter pulp, cellulosic substances such as cellulose x human silk, and cellulose obtained by processing these into refined stones are used. obtain.

In order to treat these cellulosic substances and cellulose (hereinafter referred to as cellulose), the cellulases used include commercially available cellulase preparations such as Cellulase Onozuka, Meicelase, and Pancellase, as well as, for example, Trichoderma sp., Fusarium sp. Examples include liquid culture broth or solid culture extract of cellulase-producing bacteria belonging to the genus Irpetcus.

The treatment of cellulosic substances using these cellulases is
Is the concentration of cellulose between 1 and 50% by weight? This is done by preparing cellulose and cellulase solution as much as possible and causing an enzymatic reaction.

The temperature and pH during this treatment range from 25 to 60°C and 30°C depending on the type of cellulase used.
Select as appropriate within the pH range of ~7. Furthermore, the concentration of cellulase and reaction time in the reaction system can be selectively set in consideration of the type of cellulose used, the activity of cellulase, and the degree of crystallinity required for the target crystalline cellulose. The treatment of cellulose can be terminated by stopping the enzymatic reaction by cellulase. That is, it may be carried out by methods conventionally employed for stopping enzyme reactions, such as inactivation of cellulase by heating, pH adjustment to reduce the function of cellulase by addition of acid or alkali, and the like. The enzymatic reaction can also be stopped by immediately separating the cellulose-treated product into solids and liquid to recover the cellulose solid content. Cellulosic materials treated as described above are subjected to centrifugation,
Cellulose with improved crystallinity is separated and recovered from the solubilized material by solid-liquid separation means such as filtration and sedimentation.

The obtained cellulose is washed with water to remove remaining cellulase and solubilized substances, and then dried. Incidentally, in the above-mentioned washing with water, the washing effect can be improved by using water to which an ionic or nonionic surfactant is added to the initial washing water. The cellulose obtained as described above is crushed for powdering.

This crushing is carried out using a conventional crusher such as a pole mill, rod mill, tube mill, hammer mill, or Willey mill. As described above, according to the present invention, the removal of the amorphous region from the micelle structure of cellulose can be carried out under extremely mild conditions. In addition to the advantages of not producing colored substances due to decomposition and not requiring the use of equipment made of chemically resistant materials, the desired crystallization can be achieved by adjusting the concentration of cellulase used and treatment time. The effect of controlling the crystallinity of cellulose is seen. Furthermore, since the solubilized product produced during the treatment of cellulose with cellulase in the present invention contains sugars produced as by-products from the enzymatic reaction, the liquid after separating the treated product into solid and liquid contains cellulose. It can also be used by incorporating it into enzymatic saccharification technology.

EXAMPLES The effects of the present invention will be specifically explained below with reference to Examples.

Example 1 After cutting a wood pulp sheet for dissolution into strips of appropriate size, take the 1009 and add Cellulase Onozuka (manufactured by Kinki Yakult) 59 and 0.02M acetate buffer (
PH4.5) 11 was added and reacted at 45° C. with stirring.

The obtained reaction product was immediately subjected to solid-liquid separation by centrifugation to separate cellulose, washed thoroughly with water, further dried at 60°C in a ventilation dryer, and then crushed in a Wiley mill to obtain cellulose powder. Ta. Table 1 shows the relationship between the treatment time with cellulase, the crystallinity of the obtained cellulose powder, the average degree of polymerization, and the product yield.

The degree of crystallinity was measured using the Segal method (TextlleRes
．． J. , 29, 786 (1959)), and the average degree of polymerization was calculated from viscosity measurements using copper ethylene diamine as a solvent. As shown in Table 1, the average degree of polymerization did not change much compared to the raw material. , a crystalline cellulose product with improved crystallinity was obtained. Example 2 Purified linter pulp was cut into appropriate sizes and ground in a Wiley mill, which was used as a raw material.

Claims (1)

[Claims] 1. A method for producing cellulose powder with a high degree of crystallinity, which comprises treating cellulose or cellulosic substances with cellulase, solid-liquid separation of the treated product, and mechanically crushing the resulting cellulose solid content.