JP2022084519A - Methods for producing porous cellulose particles - Google Patents

Abstract

To provide simple methods for producing porous cellulose particles and methods for providing porosity.SOLUTION: Disclosed is a method for producing porous cellulose particles comprising treating an amorphous cellulose with at least one selected from cellulase and hemicellulose in a solvent comprising step (1), where the amorphous cellulose has 50% or less cellulose I type crystallinity, and the porous cellulose particles have a median diameter of from 5 μm or more and 90 μm or less, where the cellulose I type crystallinity (%) is defined by Formula (1) [cellulose I type crystallinity (%)=(I22.6-I18.5)/I22.6]×100. In the formula, I22.6 is diffraction intensity of lattice plane (002 plane)(diffraction angle 2θ=22.6°) and I18.5 is the diffraction intensity of amorphous part (diffraction angle 2θ=18.5°) in X ray diffraction.SELECTED DRAWING: None

Description

The present invention relates to a method for producing porous cellulose particles and a method for making cellulose porous.

Conventionally, a method for producing fine spherical particles of regenerated cellulose has been known.
On the other hand, there is a report that an enzyme is allowed to act on cellulose, and Patent Document 1 has a problem of easily obtaining fine fibrous cellulose having a diameter of 1 nm to 1000 nm, and it is short by mechanically treating chemical pulp. Described is a method for producing fine fibrous cellulose, which comprises treating the fibrous and short-fibrous chemical pulp with a cellulase-based enzyme and then performing a micronization treatment with a high-speed rotary defibrator or a high-pressure homogenizer. There is.
In Patent Document 2, an amorphous cellulose having a cellulose type I crystallization degree reduced to 33% or less is prepared with an object of efficiently obtaining a sugar, and then cellulase and / or hemicellulase is added to the amorphous cellulose. A method for producing a sugar, which is saccharified by the action of the above, is disclosed.

Japanese Unexamined Patent Publication No. 2012-46846 Japanese Unexamined Patent Publication No. 2009-171952

In Patent Document 1, an enzyme is allowed to act on the subject of obtaining fine cellulose, and in the method of Patent Document 2, an enzyme is allowed to act for saccharification, which is a problem of porosity. In this respect, it cannot be said that sufficient consideration has been given.
The present invention relates to providing a production method and a porosification method capable of easily producing porous cellulose particles.

The present inventors have found that the above-mentioned problems can be solved by allowing an enzyme to act on cellulose having a specific crystallinity.

That is, the present invention relates to the following [1] and [2].
[1] A method for producing porous cellulose particles, which comprises the following step 1.
Step 1: A step of allowing at least one selected from cellulase and hemicellulase to act on the non-crystallized cellulose in a solvent. The non-crystallized cellulose has a cellulose type I crystallinity defined by the following formula (1). Is 50% or less, and the median diameter of the porous cellulose particles is 5 μm or more and 90 μm or less, a method for producing porous cellulose particles.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.)
[2] A method for making cellulose porous, which comprises the following step I.
Step I: A step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose in a solvent. The amorphous cellulose is the cellulose type I crystallinity defined by the following formula (1). Is 50% or less, and the median diameter of the porous cellulose particles is 5 μm or more and 90 μm or less.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.)

According to the present invention, porous cellulose particles can be easily obtained.

[Method for producing porous cellulose particles]
The method for producing porous cellulose particles of the present invention is a method for producing porous cellulose particles having the following step 1.
Step 1: A step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose in a solvent. The amorphous cellulose is a cellulose type I crystal defined by the following formula (1). The degree of crystallization is 50% or less, and the median diameter of the obtained porous cellulose particles is 5 μm or more and 90 μm or less.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.)
According to the present invention, porous cellulose particles can be easily obtained.

The detailed mechanism by which the above effects are obtained is unknown, but it is presumed as follows.
That is, by allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose, the amorphous portion of the amorphous cellulose is decomposed by the enzyme, and as a result, the pore volume. It is probable that the number of particles increased and porous cellulose particles were obtained.

In the present invention, it is preferable to have the following step 0 before the step 1.
Step 0: A step of converting a cellulose-containing raw material having a cellulose I-type crystallization degree of more than 50% into an amorphous cellulose having a cellulose I-type crystallization degree of 50% or less. Further, after the step 1, the following step 2 is provided. Is preferable.
Step 2: A step of allowing at least one selected from cellulase and hemicellulase to act and then drying the amorphous cellulose to obtain porous cellulose particles. In the following description, the degree of cellulose type I crystallinity of cellulose is determined. Sometimes it is simply called "crystallinity".
Hereinafter, steps 0 to 2 will be described.

<Step 0>
Step 0 is a step of converting a cellulose-containing raw material having a cellulose I-type crystallization degree of more than 50% into an amorphous cellulose having a cellulose I-type crystallization degree of 50% or less. Cellulose type I crystallinity is represented by the following formula (1).
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
[I _22.6 indicates the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and _I18.5 indicates the amorphous portion (diffraction angle 2θ = 18.5 °). ) Is shown. ]

[Cellulose type I crystallinity]
The amorphous cellulose prepared in step 0 has a cellulose type I crystallinity reduced to 50% or less. The crystallinity is calculated by the Segal method from the diffraction intensity value by the X-ray diffraction method, and is defined by the following formula (1).
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
[I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the diffraction intensity of the amorphous part (diffraction angle 2θ = 18.5 °). Indicates the diffraction intensity. ]
When the crystallinity is 50% or less, the chemical reactivity of cellulose is improved, and the pore capacity can be further improved by porosification. From this viewpoint, the crystallinity is preferably 40% or less, more preferably 30% or less, still more preferably 25% or less, and particularly preferably 0% or less in which type I crystals are not detected in the analysis. In addition, the cellulose type I crystallinity defined by the formula (1) may have a negative value in calculation.

Here, the cellulose type I crystallinity is a ratio of the amount of the crystalline region of cellulose to the total amount. Further, the cellulose type I is a crystalline form of natural cellulose. The degree of crystallinity is also related to the physical and chemical properties of cellulose, and the larger the value, the higher the crystallinity of cellulose and the smaller the number of non-crystalline parts, so the hardness, density, etc. increase, but the elongation, flexibility, etc. Solubility and chemical reactivity with water and solvents are reduced.

[Cellulose-containing raw material]
The cellulose-containing raw material is not particularly limited, and woods such as various wood chips, pruned branches, thinned wood, and branch wood; wood pulp produced from wood, cotton linter pulp obtained from fibers around cotton seeds, etc. Pulps; papers such as newspapers, cardboards, magazines, and high-quality papers; plant stems and leaves such as rice straw and corn stalks; plant shells such as rice husks, palm husks, and coconut husks. Among these, pulps, papers, and plant stems / leaves are preferable, pulps and papers are more preferable, and it is further preferable to be selected from wood-derived pulps.
The cellulose-containing raw material used in the present invention has a cellulose content of preferably 20% by mass or more, more preferably 40% by mass or more, still more preferably 60% by mass or more in the residual component obtained by removing water from the raw material. Is.
The cellulose content means the total amount of cellulose and hemicellulose.
In the case of commercially available pulp, the cellulose content in the residual component excluding water is generally 75% by mass or more and 99% by mass or less, and other components include lignin and the like. The degree of cellulose I-type crystallinity of commercially available sheet pulp is usually 60% or more.

The water content in the cellulose-containing raw material is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less. When the water content in the cellulose-containing raw material is 20% by mass or less, it can be easily pulverized, and the crystallinity can be easily lowered by the pulverization treatment, and the production of porous cellulose particles by the subsequent enzyme treatment is efficient. You can do it well.

The size of the cellulose-containing raw material used in the present invention is preferably 1 mm square or more and 50 mm square or less, and more preferably 1 mm square or more and 30 mm square or less. By coarsely pulverizing into chips of 1 mm square or more and 50 mm square or less, the amorphous treatment described later can be easily performed.

Examples of the method of coarsely pulverizing the cellulose-containing raw material into chips include a method using a shredder, a sheet pelletizer, or a rotary cutter.

The coarsely pulverized cellulose raw material is preferably subjected to a drying treatment prior to the amorphous treatment described later. The method of the drying treatment is not particularly limited, and examples thereof include a stirring dryer.

[Amorphous treatment]
As the amorphization treatment, it is preferable to treat the cellulose-containing raw material with a pulverizer to reduce the degree of cellulose type I crystallization in the cellulose to 50% or less. By treating with a pulverizer, the cellulose-containing raw material can be further pulverized, the crystallinity can be lowered, and the cellulose can be efficiently amorphous.
As the crusher, a medium type crusher can be preferably used. The medium-type crusher includes a container-driven crusher and a medium-stirring type crusher. Examples of the container-driven crusher include a rolling mill, a vibration mill, a planetary mill, and a centrifugal flow mill. Among these, a vibration mill is preferable from the viewpoint of high pulverization efficiency and productivity. As a medium stirring type crusher, a tower type crusher such as a tower mill; a stirring tank type crusher such as an attritor, an aquamizer, or a sand grinder; a distribution tank type crusher such as a viscomill or a pearl mill; a distribution tube type crusher; Annual type crusher; continuous dynamic type crusher and the like can be mentioned. Among these, a stirring tank type crusher is preferable from the viewpoint of high crushing efficiency and productivity. When a medium stirring type pulverizer is used, the peripheral speed of the tip of the stirring blade is preferably 0.5 m / s or more, more preferably 1 m / s or more, and preferably 20 m / s or less, more preferably 15 m. It is less than / s.
For the types of crushers, refer to "Advances in Chemical Engineering Vol. 30 Fine Particle Control" (edited by Tokai Branch of the Chemical Engineering Society, published on October 10, 1996, Maki Shoten).
As the processing method, either a batch method or a continuous method may be used.

The material of the medium of the crusher is not particularly limited, and examples thereof include iron, stainless steel, alumina, zirconia, silicon carbide, silicon carbide, and glass.
When the crusher is a vibration mill and the medium is a ball, the outer diameter of the ball is preferably 0.1 mm or more, more preferably 0.5 mm or more, and preferably 100 mm or less, more preferably. Is 50 mm or less. When the size of the ball is within the above range, a desired crushing force can be obtained, and cellulose can be efficiently amorphous without contaminating the cellulose-containing raw material due to contamination by pieces of the ball or the like. ..
The filling rate of the balls varies depending on the model of the vibration mill, but is preferably in the range of 10% or more and 97% or less, and more preferably 15% or more and 95% or less. When the filling rate is within this range, the contact frequency between the cellulose-containing raw material and the balls can be improved, and the pulverization efficiency can be improved without hindering the movement of the medium. Here, the filling factor means the apparent volume of the ball with respect to the volume of the stirring portion of the vibrating mill.
When the crusher is a vibration mill and the medium is a rod, the diameter of the rod is preferably 1 mm or more, more preferably 5 mm or more, and preferably 300 mm or less, more preferably 100 mm or less, and further. It is preferably 50 mm or less.
As the medium, a medium such as a tube can be used in addition to the ball and the rod.
The processing time of the vibration mill cannot be unconditionally determined depending on the type of the vibration mill, the type of the medium, the size, the filling rate, etc., but is preferably 5 minutes or more and 72 hours or less from the viewpoint of reducing the crystallinity. The treatment temperature is not particularly limited, but is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, still more preferably 100, from the viewpoint of preventing deterioration due to heat. ° C or lower, more preferably 50 ° C or lower.

By the above treatment method, amorphous cellulose having a cellulose type I crystallization degree of 50% or less can be efficiently obtained using a cellulose-containing raw material as a starting material, and the inside of the crusher is used during the crusher treatment. The cellulose-containing raw material does not adhere to the surface and can be treated by a dry method.
The average particle size (median diameter) of the obtained uncrystallized cellulose is preferably 10 μm or more, more preferably 20 μm or more, and preferably 150 μm or less, from the viewpoint of obtaining porous cellulose particles having a desired median diameter. It is more preferably 100 μm or less.
The median diameter of amorphous cellulose is measured by the method described in Examples.

<Step 1>
Step 1 is a step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose having a crystallinity of 50% or less in a solvent. The mixed solution containing at least one selected from cellulase and hemicellulase and amorphous cellulose in the solvent in step 1 is hereinafter also referred to as a reaction solution.
The amorphous cellulose obtained by the above-mentioned amorphous treatment has a low crystallinity, and is subjected to enzymatic treatment with at least one selected from cellulase and hemicellulase (hereinafter, also simply referred to as "cellulase and the like"). It is considered that the amorphous portion is preferentially decomposed by cellulase or the like.
The term "cellulase" as used herein refers to an enzyme that hydrolyzes the glycoside bond of β-1,4-glucan of cellulose, and is a general term for enzymes called endoglucanase, exoglucanase, cellobiohydrolase, β-glucosidase, and the like. ..
Further, hemicellulase is a general term for enzymes that hydrolyze hemicellulose (EC 3.2.1.8 or EC 3.21.89). Hemicellulose is a polysaccharide that is alkaline-extracted from plant tissues, and examples of the main polysaccharides include xylan, arabinoxylan, xyloglucan, and glucomannan.
Cellulase and hemicellulase may be used alone or in combination of two or more. In addition, any of a mode in which two or more kinds of cellulase are used in combination and a mode in which cellulase and hemicellulase are used in combination are not particularly limited.

The cellulase and hemicellulase used in the present invention are not particularly limited, and commercially available cellulase preparations and those derived from animals, plants and microorganisms can be used.
Examples of cellulase include cellulase preparations derived from Trichoderma reesei such as Cellulase 1.5L (Novozymes), cellulase derived from Bacillus sp. KSM-N145 (FERM P-19727), or cellulase. Bacillus sp. KSM-N252 (FERM P-17474), Bacillus sp. KSM-N115 (FERM P-19726), Bacillus sp. KSM-N440 (FERM P-19728), Cellulase derived from each strain such as Bacillus sp. KSM-N659 (FERM P-19730), as well as Trichoderma viride, Aspergillus acryatas (Aspergillus acleatus), Crostridium cellulase, and crosstridium cellulase.リウム（Ｃｌｏｓｔｒｉｄｉｕｍ ｓｔｅｒｃｏｒａｒｉｕｍ）、クロストリジウム ジョスイ（Ｃｌｏｓｔｒｉｄｉｕｍ ｊｏｓｕｉ）、セルロモナス フィミ（Ｃｅｌｌｕｌｏｍｏｎａｓ ｆｉｍｉ）、アクレモニウム セルロリティクス（Ａｃｒｅｍｏｎｉｕｍ ｃｅｌｌｕｌｏｒｉｔｉｃｕｓ）、イルペックス ラクテウス（Ｉｒｐｅｘ ｌａｃｔｅｕｓ）、アスペルギルス ニガー（Ａｓｐｅｒｇｉｌｌｕｓ ｎｉｇｅｒ）、フミコーラ インソレンス（Ｈｕｍｉｃｏｌａ ｉｎｓｏｌｅｎｓ） Examples thereof include a cellulase mixture derived from the cellulase and a heat-resistant cellulase derived from Pyrococcus horikoshii.

Examples of hemicellulase include xylanase derived from Bacillus sp. KSM-N546 (FERM P-19729), Aspergillus niger, Trichoderma vilide, and Filcola. , Bacillus alkalofilus-derived xylanase, as well as Thermomyces, Aureobasideium, Streptomyces, Streptomyces, Clostridium, Clostridium Examples thereof include Caldocellum, xylanase derived from the genus Thermomonospora, and the like. In addition, an enzyme having hemicellulase activity contained in the above cellulase mixture can also be used.

Among these, porous cellulose can be efficiently produced by preferably using cellulase or the like derived from Trichoderma reesei.
Further, as cellulase or the like, it is preferable to contain at least cellulase, and it is more preferable to contain at least endoglucanase.

It is also possible to improve the production efficiency of porous cellulose by further adding a specific cellulase component such as β-glucosidase to these enzymes. Examples of β-glucosidase to be added include enzymes derived from Aspergillus niger (for example, β-glucosidase manufactured by Megazyme), Agrobacterium, Thermotoga maritima, Trichoderma, and Trichoderma. Examples thereof include enzymes derived from Penicillium emersonii.

In step 1, the reaction conditions for treating amorphous cellulose with cellulase or the like in a solvent can be appropriately selected depending on the crystallinity of the amorphous cellulose and the enzyme used.
Water is preferable as the solvent to be used, and a buffer solution is preferably used from the viewpoint of obtaining high enzyme activity.
The pH of the reaction solution at which cellulase or the like is allowed to act may be appropriately selected depending on the optimum pH of the enzyme to be used, but is generally preferably 2 or more, more preferably 3 or more, and preferably 13 or less. , More preferably 12 or less.
The temperature of the reaction solution when the cellulase or the like is allowed to act may be appropriately selected depending on the optimum temperature of the enzyme to be used, but is preferably 20 ° C. or higher, more preferably 25 ° C. or higher from the viewpoint of obtaining high enzyme activity. , And preferably 70 ° C. or lower, more preferably 60 ° C. or lower.
The reaction time when the cellulase or the like is allowed to act is preferably 12 hours or longer, more preferably 24 hours or longer, still more preferably 36 hours or longer, and preferably 36 hours or longer, from the viewpoint of achieving both productivity and sufficient enzymatic reaction. Is 72 hours or less, more preferably 60 hours or less.

The total amount of cellulase or the like in the reaction solution when the cellulase or the like is allowed to act is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, still more preferably 0.01% by mass or more, still more preferably. It is 0.015% by mass or more, and preferably 1% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.08% by mass or less. The total amount of cellulase and the like in the reaction solution means the content of cellulase and the like as the amount of protein.
The content of the uncrystallized cellulose in the reaction solution is preferably 1% by mass or more, more preferably 3% by mass, from the viewpoint of obtaining high enzyme activity, uniformly performing the enzyme treatment, and the fluidity of the treatment solution. % Or more, more preferably 5% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less.

The mass ratio of the total content of cellulase and hemicellulase to uncrystallized cellulose ((cellulase + hemicellulase) / amorphous cellulose) is preferably 2.5 × 10 ^-5 or more, more preferably 2.5 × 10. ^-4 or more, more preferably 1.0 × 10 ^-3 or more, and preferably 2.5 × 10 ^-1 or less, more preferably 5 × 10 ^{-2- or less, still more preferably 1 × 10 -2 or} less. Is.
The total content of cellulase and hemicellulase means the mass as the amount of protein.

When the cellulase or the like is allowed to act, it is preferable to stir or shake the reaction solution.
In the case of stirring, the blade selection speed of the stirring blade is preferably 0.1 m / s or more, more preferably 0.5 m / s or more, still more preferably 1.0 m / s from the viewpoint of obtaining high enzyme activity. The above, and preferably 10 m / s or less, more preferably 8.0 m / s or less, still more preferably 5.0 m / s or less.
Further, when shaking is performed, reciprocating shaking or swirling shaking may be used, and the shaking is not particularly limited, but from the viewpoint of obtaining high enzyme activity, it is preferably 10 rpm or more, more preferably 30 rpm or more, still more preferably 100 rpm. The above, and preferably 1000 rpm or less, more preferably 500 rpm or less, still more preferably 200 rpm or less.

<Step 2>
Step 2 is a step of spray-drying or freeze-drying the amorphous cellulose after allowing cellulase or the like to act on it to obtain porous cellulose particles.
From the viewpoint of suppressing the aggregation of the porous cellulose particles due to drying, freeze-drying or spray-drying is preferable as the drying treatment, and freeze-drying is more preferable.
For spray drying, for example, it is preferable to spray the reaction solution after the completion of step 1 in a spray drying device and dry it at an inlet temperature of 200 ° C. or lower and an outlet temperature of 110 ° C. or lower.
For freeze-drying, it is preferable to perform primary drying and secondary drying after pre-freezing the reaction solution after the completion of step 1.
The pre-freezing is preferably quick freezing at a temperature of −40 ° C. or higher and −20 ° C. or lower under normal pressure. Then, a primary drying is performed to sublimate the ice in the pre-frozen product under a vacuum of 0.1 Pa or more and 100 Pa or less, and at a temperature of -20 ° C or more and -5 ° C or less, and then a vacuum of 0.1 Pa or more and 100 Pa or less is performed. It is preferable to perform secondary drying at a lower temperature and a temperature of 20 ° C. or higher and 40 ° C. or lower.
Step 2 may further include a step of pulverizing the porous cellulose particles obtained after the drying treatment.

<Physical characteristics of porous cellulose particles>
The porous cellulose obtained by the method for producing porous cellulose particles of the present invention has a median diameter of 5 μm or more and 90 μm or less. When the median diameter is within the above range, it is expected to be applied to various uses as alternative particles for microplastics.
The median diameter of the porous cellulose particles is preferably 10 μm or more, more preferably 20 μm or more, and preferably 75 μm or less, more preferably 60 μm, in consideration of ease of manufacture and applicability to various applications. It is as follows.
The median diameter of the porous cellulose particles is produced by the method described in Examples.
It should be noted that the median diameter may be reduced by allowing cellulase or the like to act on the amorphous cellulose. It is considered that this is a result of decomposition of cellulose and hemicellulose by cellulase and the like.

The pore volume of the porous cellulose is increased as compared with the pore volume of the amorphous cellulose before the action of cellulase or the like.
By allowing cellulase or the like to act, the pore volume of the porous cellulose is preferably increased by 10% or more, more preferably 50% or more, still more preferably 100% or more, as compared with the pore volume of the amorphous cellulose. ing. The upper limit thereof is not particularly limited, but is, for example, 300% or less from the viewpoint of ease of manufacture.

The pore volume of the porous cellulose of 10 μm or less is preferably 0.30 mL / g or more, more preferably 0.35 mL / g or more, still more preferably 0.40 mL / g or more from the viewpoint of forming the porous cellulose. The upper limit is not particularly limited, but is, for example, 2.0 mL / g or less, more preferably 1.8 mL / g or less, still more preferably 1.5 mL / g or less, from the viewpoint of ease of production.
The pore volume of the porous cellulose is measured by the method described in Examples.

[Method for making cellulose porous]
The method for making cellulose porous according to the present embodiment is a method for making cellulose porous having the following step I.
Step I: A step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose in a solvent. The amorphous cellulose is the cellulose type I crystallinity defined by the following formula (1). Is 50% or less, and the median diameter of the porous cellulose particles is 5 μm or more and 90 μm or less.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.)
Step I is the same as in Step 1, and the same conditions as in Step 1 can be adopted for the amorphous cellulose, solvent, cellulase and the like to be used, reaction conditions and the like, and the preferred range is also the same.
Further, step 0 related to the preparation of amorphous cellulose and step 2 related to the drying step can be similarly adopted, and the preferred range is also the same.

The porous cellulose particles obtained by the present invention are expected to be applied to various uses in which microplastics have been used.

The median diameter, X-ray diffraction intensity, and pore volume of the amorphous cellulose or the cellulose-containing raw material were measured by the methods described below. In addition, the enzymatic treatment reaction of various celluloses such as amorphous cellulose was carried out under the conditions described below.

(1) Measurement of median diameter The median diameter (medium volume particle size, D ₅₀ ) was measured using a laser diffraction / scattering type particle size distribution measuring device “LA-920” (manufactured by HORIBA, Ltd.). The measurement conditions were as follows: treatment was performed with ultrasonic waves for 1 minute before measuring the particle size, water was used as a dispersion medium at the time of measurement, and the measurement was performed at a temperature of 25 ° C.

(2) Measurement of X-ray diffraction intensity The X-ray diffraction intensity is measured under the following conditions using "MiniFlex-II" manufactured by Rigaku Co., Ltd., and the degree of cellulose I-type crystallinity is determined based on the above formula (1). Calculated.
The measurement conditions are as follows.
X-ray source: Cu / Kα-radiation
Measurement range: 2θ = 5 to 50 °
The measurement sample was prepared by compressing it into pellets having an area of 320 mm ² × thickness of 1 mm. The X-ray scan speed was measured at 5 ° / min.
In the cellulose type I crystal, a peak (I _22.6 ) corresponding to the 002 plane is expressed at a diffraction angle of 2θ = 22.6 °. The crystallinity (X [%]) is generally calculated by the following formula using a peak intensity (I _18.5 ) of 2θ = 18.5 ° reflecting the amorphous portion.
X = (I _22.6 -I _18.5 ) / I _22.6 x 100

(3) Evaluation of Pore Volume The evaluation of the pore volume was carried out by a mercury porosimeter (Auto Pore IV 9500) manufactured by Shimadzu Corporation. About 0.05 g of the powder sample was placed in the cell, and the measurement was carried out in the measurement pressure range of 0.01 MPa to 210 MPa. In the mercury intrusion method, the measured pressure (intrusion pressure) corresponds to the pore diameter, and the pore diameter distribution can be measured from the relationship between the measured pressure and the mercury intrusion amount. This time, in order to evaluate the volume of the pores in the particles newly generated by the enzyme treatment, the pore volume having a pore diameter of 10 μm or less was evaluated.

Example 1
[Preparation of amorphous cellulose]
As a cellulose-containing raw material, sheet-shaped wood pulp [“Biofloc HV +” manufactured by Tembeck Co., Ltd., 800 mm × 600 mm × 1 mm, crystallinity 82%, cellulose content 96% by mass in the residual component obtained by removing water from the cellulose-containing raw material, Moisture content 8.5% by mass] was applied to a sheet pelletizer (manufactured by Horai Co., Ltd., “SG (E) -220”) and cut into a size of about 4 mm × 4 mm × 1 mm.
The pulp obtained by the cutting treatment was dried using a twin-screw horizontal stirring dryer [manufactured by Nara Machinery Co., Ltd., product name "two-screw paddle dryer, NPD-3W (1/2) LG"]. The drying temperature was set to 150 ° C., 20 kg of pulp was charged in advance, and the pulp was dried by batch processing for 60 minutes.
920 g of the pulp obtained by the drying treatment was put into a batch type vibration mill (manufactured by Chuo Kakoki Co., Ltd., "FV-10", mill inner diameter 284 mm, depth 226 mm), and used as a rod with a diameter of 30 mm, a length of 510 mm, and a material. A rod made of stainless steel and having a circular cross-sectional shape was filled in a vibration mill and treated at room temperature (20 ° C.) for 10 minutes under the conditions of an amplitude of 8 mm and a circular rotation of 20 cpm. Table 1 shows the average particle size, crystallinity, and pore volume of the obtained amorphous cellulose.

[Enzymes and reagents used]
・ Enzyme: Cellulase from Trichoderma reesei (aqueous solution,> 700units / g), manufactured by Merck ・ Buffer solution: pH 5.10 Sodium oxalate buffer (5-fold concentrate, for biological sample), Fujifilm Wako Pure Chemical Industries, Ltd. Made by the company

[Enzyme treatment of amorphous cellulose]
The study was carried out using the above-mentioned amorphous cellulose and enzyme.
To a 500 mL Erlenmeyer flask, 10 g of amorphous cellulose, 500 μL of enzyme, 20 g of pH buffer (sodium citrate buffer (5-fold concentrated solution)), and 69 g of ion-exchanged water were added. This Erlenmeyer flask was transferred to a shaker (manufactured by Takasaki Kagaku Kikai Co., Ltd., TXY-30R-3F) set at 50 ° C. and shaken at 150 rpm for 48 hours to perform enzyme treatment. In this treatment, the enzyme concentration in the treatment liquid was 0.0175% by mass as the protein concentration. The mass ratio of the enzyme to the amorphous cellulose as a protein (enzyme / amorphous cellulose) was 1.75 × 10 ^-3 .
The slurry after the enzyme treatment was transferred to a 50 mL centrifuge tube and centrifuged (9000 G, 5 min, 4 ° C.) for solid-liquid separation. After removing the supernatant, ion-exchanged water was added to the remaining solid content to make a volumetric flask with a total volume of 50 mL, and the solid content was washed by redispersing with a vortex mixer. This slurry was centrifuged again (9000 G, 5 min, 4 ° C.) to perform solid-liquid separation.
The solid content obtained by removing the supernatant was pre-frozen at −30 ° C. and then dried overnight in a freeze dryer (manufactured by EYELA, FDU-1200 type). Since the solid after freeze-drying was not in powder form and partly solidified, the mass was broken down with a spatula as necessary and evaluated. Table 1 shows the average particle size and pore volume of the obtained amorphous cellulose.

Example 2
[Preparation of amorphous cellulose]
Preparation was performed by changing the treatment time of the batch type vibration mill to 30 minutes in [Preparation of Amorphous Cellulose] of Example 1. Table 1 shows the average particle size, crystallinity, and pore volume of the obtained amorphous cellulose.

[Enzymes and reagents used]
The same enzymes and reagents as in Example 1 were used.
[Enzyme treatment of amorphous cellulose]
In Example 1, the study was carried out by changing the amorphous cellulose to be used to one in which the processing time of the batch type vibration mill was 30 minutes. Table 1 shows the average particle size and pore volume of the obtained amorphous cellulose.

Comparative Example 1
[Cellulose species]
KC floc (W-50GK, manufactured by Nippon Paper Chemicals Co., Ltd.) was used. Table 1 shows the crystallinity and pore volume of this cellulose. Since this cellulose is cotton-like, the average particle size has not been measured.
[Preparation of enzyme]
The same enzyme as in Example 1 was used.
[Enzyme treatment of amorphous cellulose]
In Example 1, the study was carried out by changing to the KC floc (W-50GK, manufactured by Nippon Paper Chemicals Co., Ltd.) to be used. Table 1 shows the average particle size and pore volume of the obtained amorphous cellulose.

Comparative Example 2
[Cellulose species]
As the cellulose-containing raw material, the same sheet-shaped wood pulp as in Example 1 [“Biofloc HV +” manufactured by Tembeck Co., Ltd., 800 mm × 600 mm × 1 mm, crystallinity 82%, cellulose-containing in the residual component obtained by removing water from the cellulose-containing raw material. Amount of 96% by mass, water content of 8.5% by mass] was applied to a sheet pelletizer (manufactured by Horai Co., Ltd., “SG (E) -220”) and cut into a size of about 4 mm × 4 mm × 1 mm.
The pulp obtained by the cutting treatment was dried using a twin-screw horizontal stirring dryer [manufactured by Nara Machinery Co., Ltd., product name "two-screw paddle dryer, NPD-3W (1/2) LG"]. The drying temperature was set to 150 ° C., 20 kg of pulp was charged in advance, and the pulp was dried by batch processing for 60 minutes.
[Preparation of enzyme]
The same enzyme as in Example 1 was used.
[Enzyme treatment of cellulose]
The study was carried out by changing the cellulose used in Example 1 to the above Bioflock HV + dried chip (without amorphous treatment). Table 1 shows the average particle size and pore volume of the obtained cellulose.

According to the production method of the present invention, porous cellulose particles can be easily obtained.

Claims (8)

It is a method for producing porous cellulose particles having the following step 1.
Step 1: A step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose in a solvent. The amorphous cellulose is the cellulose type I crystallinity defined by the following formula (1). Is less than 50%,
The median diameter of the porous cellulose particles is 5 μm or more and 90 μm or less.
A method for producing porous cellulose particles.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.) The production method according to claim 1, wherein the amorphous cellulose is an amorphous cellulose obtained by treating a cellulose-containing raw material with a medium-type pulverizer. The production method according to claim 2, wherein the cellulose-containing raw material is selected from pulps derived from wood. The production method according to any one of claims 1 to 3, wherein the solvent in step 1 is water. The production method according to any one of claims 1 to 4, wherein the concentration of amorphous cellulose in step 1 is 1% by mass or more and 40% by mass or less. In step 1, the total content of cellulase and hemicellulase to non-crystallized cellulose ((cellulase + hemicellulase) / amorphous cellulose, mass ratio) is 2.5 × 10 ^-5 or more and 2.5 × 10 ^-1 . The manufacturing method according to any one of claims 1 to 5, which is described below. The production method according to any one of claims 1 to 6, further comprising a step of spray-drying or freeze-drying the amorphous cellulose after the step 1 to obtain porous cellulose particles. A method for making cellulose porous, which comprises the following step I.
Step I: A step of allowing at least one selected from cellulase and hemicellulase to act on the amorphous cellulose in a solvent. The amorphous cellulose is the cellulose type I crystallinity defined by the following formula (1). Is less than 50%,
The median diameter of the porous cellulose particles is 5 μm or more and 90 μm or less.
Method for making cellulose porous.
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] x 100 (1)
(Here, I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in the X-ray diffraction, and _I18.5 is the amorphous portion (diffraction angle 2θ = 18. 5 °) diffraction intensity.)