JP2012111849A - Method for producing microfibrous cellulose, method for producing microfibrous cellulose sheet, and microfibrous cellulose composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing microfibrous cellulose having 1-1,000 nm fiber width in high yield and a method for producing a microfibrous cellulose sheet using the microfibrous cellulose, in addition, a method for producing a transparent composite material even having low discoloration (evaluated with YI value after heating at 200°C) in a microfiber cellulose composite prepared by impregnating the microfibrous cellulose with a polymer and curing the same.SOLUTION: The microfibrous cellulose with little discoloration (low in YI value after heating) in a composite compounded with a polymer can be produced in high yield by carrying out fat removal, lignin removal and hemicellulose removal treatments of wood flour, removing residual lignin by bleaching treatment, subsequently treating the same with a cellulase-based enzyme and mechanically fiber-opening the same by a high-speed rotation type fiber-opening machine or high pressure homogenizer.

Description

  The present invention is a method for producing fine fibrous cellulose, in which fine fibrous cellulose having a fiber width of 1 nm to 1000 nm can be easily obtained by enzymatically defibrating chemically treated wood powder, The present invention relates to a production method of a fine fibrous cellulose sheet and a fine fibrous cellulose composite, and specifically relates to a production method capable of providing a fine fibrous cellulose composite with little coloring.

In recent years, nanotechnology aimed at obtaining physical properties different from the bulk and molecular levels by making a material a nanometer size has attracted attention. On the other hand, attention is also focused on the application of natural fibers that can be regenerated due to the substitution of petroleum resources and the growing environmental awareness.
Among natural fibers, cellulose fibers, particularly wood-derived cellulose fibers (pulp) are widely used mainly as paper products. Most cellulose fibers used for paper have a width of 10 to 50 μm. Paper (sheet) obtained from such cellulose fibers is opaque and is widely used as printing paper because it is opaque. On the other hand, when the cellulose fiber is treated (beating, pulverizing) with a refiner, kneader, sand grinder or the like, and the cellulose fiber is refined (microfibril), a transparent paper (glassine paper or the like) is obtained. However, the transparency of the transparent paper is at a semi-transparent level, the light transmittance is lower than that of the polymer film, and the haze level (haze value) is large.

Cellulose fibers are aggregates of cellulose crystals with a high modulus of elasticity and a low coefficient of thermal expansion, and heat resistant dimensional stability is improved by compositing cellulose fibers with polymers. Yes. However, normal cellulosic fibers are aggregates of crystals, and are fibers having cylindrical voids, so that dimensional stability is limited.
The aqueous dispersion of fine fibrous cellulose having mechanically pulverized cellulose fibers and having a fiber width of 50 nm or less is transparent. On the other hand, since the fine fibrous cellulose sheet contains voids, it is irregularly reflected white and becomes highly opaque. However, when the fine fibrous cellulose sheet is impregnated with a polymer resin, the voids are filled, so that a transparent sheet is obtained. Furthermore, the fibers of the fine fibrous cellulose sheet are an aggregate of cellulose crystals, very stiff, and because the fiber width is small, the number of fibers is dramatically increased at the same mass compared to ordinary cellulose sheets (paper). To be more. Therefore, when composited with a polymer, fine fibers are dispersed more uniformly and densely in the polymer, and the heat-resistant dimensional stability is dramatically improved. Moreover, since the fibers are thin, the transparency is high. A fine fibrous cellulose composite having such characteristics is expected to be very large as a flexible transparent substrate (a transparent substrate that can be bent or folded) for organic EL or liquid crystal displays.

  However, even if it is combined with a polymer using fine fibrous cellulose to obtain a transparent substrate, several heating (about 170 to 240 ° C.) treatment is essential in the actual device forming step. When heat treatment is performed, there is a problem that a small amount of lignin remaining in the fine fibrous cellulose, hemicellulose, or a reducing end group of cellulose or coloring components react with each other, and a YI value (Yellowing Index) is determined as an index. ing. In order to prevent the coloring, in the process of producing fine fibrous cellulose in advance, a trace amount of lignin remaining in the raw material, hemicellulose, reducing end groups or extraction components of cellulose are removed as much as possible, or their content is It is required in production to select a small amount of raw materials.

  When removing trace amounts of lignin, hemicellulose, reducing end groups of cellulose or extracted components in the raw material, cellulose has a layer structure in wood, and it is chemically combined with components such as lignin and hemicellulose. Therefore, they cannot be removed by mechanical grinding alone. Therefore, in a final product obtained by combining such a fiber and a polymer and subjected to heat treatment (about 170 to 240 ° C.) for several hours, fading occurs and the YI value becomes high, and the maximum fiber width is 1000 nm or less. It becomes difficult to obtain fibrous cellulose. Therefore, a method in which a chemical or biological treatment and a mechanical grinding treatment are combined is generally used.

  As a method of this combination, Non-Patent Document 1 discloses that a pulp is slightly hydrolyzed, washed with filtered water, dried and pulverized, and a method for producing cellulose fine particles partially containing amorphous regions or purified pulp with hydrochloric acid or sulfuric acid. Discloses a technique of hydrolyzing and pulverizing only the crystalline region. However, the level of refinement is not sufficient, and the transparency of the resulting aqueous suspension of fine fibrous cellulose is also insufficient.

  Patent Document 1 discloses a technique for obtaining fine fibrous cellulose having a water holding power of 210% or more by wet-grinding fibrous cellulose pretreated with enzymes such as cellulase and xylanase or chemical treatment using a vibration mill. Yes. However, this method has a problem that the refinement does not proceed sufficiently, and the efficiency of the enzyme reaction is still low, so it cannot be said that it is a method for producing fine fibrous cellulose with high productivity.

Non-Patent Document 2 discloses that when Trichoderma EG II is allowed to act on microcrystalline cellulose purified with 2.5N hydrochloric acid and stirred for 3 days at 40 ° C., fibrillated microcrystalline fibers are obtained and fibrillated fibers. The width was 11 nm and the length was 2300 nm. However, the fibrillated fibers are agglomerated and do not fall apart. Therefore, it is difficult to form the fine fibrous cellulose into a sheet, and it is difficult to use it industrially.

  In Patent Document 2, cellulose fibers are dispersed in water, preliminarily defibrated with a refiner or a stone mill, and steamed at a temperature of 105 to 160 ° C., and then treated with an enzyme such as cellulase, xylanase, or hemicellulase. Thereafter, a technique for producing nanofibers with a high-pressure homogenizer or a twin-screw kneader is disclosed. Although nanofibers can be obtained by this method, there is a problem that production efficiency (yield of microfibrillation) is low.

  In Patent Document 3, the microfibril cellulose aggregate or the microfibril cellulose itself was partially loosened by a treatment such as stirring, thereby improving the permeability of the enzyme into cellulose and at the same time causing the loosening. A technique for obtaining finer cellulose nanofibers by further fibrillating microfibril cellulose by causing endoglucanase to act on the amorphous part is disclosed. However, there is no disclosure at all regarding the YI value before heating and after heating, when this nanofiber is composited with a polymer.

  Patent Document 4 discloses a step of wet-disaggregating a cellulose-based fiber raw material, a preliminary defibrating step of coarsening the disaggregated fiber raw material, and applying ultrasonic waves to the pre-defamed fiber raw material to make a fine fiber. A technique is disclosed in which an enzyme is allowed to act on a fiber raw material at any point in time until the sonication process is completed in a production method in which the sonication process is refined in the order of the sonication process. However, the effect of the enzyme treatment is not remarkable, and the miniaturization efficiency is low.

  Patent Document 5 discloses a technique for treating a pulp containing hemicellulose with hemicellulase, cellulase, or a mixture thereof, and purifying (defibrating) the resulting pulp to form microfibrils, but the defibrating efficiency is low. There is a problem. Furthermore, the obtained nanofibers are combined with a polymer, and the YI values before heating and after heating are not disclosed at all.

  In Patent Document 6 and Patent Document 7, cellulose raw materials such as hardwood and softwood pulp are oxidized using an oxidizing agent in the presence of an N-oxyl compound and bromide / iodide to wet the oxidized cellulose. A method for producing a printing paper by performing atomization and using the cellulose nanofiber as an additive for papermaking is described. However, in this method, since hydrophilic groups are introduced on the surface of the cellulose fiber, impregnation with a hydrophobic polymer becomes a problem.

  A method has been proposed in which wood powder is used as a raw material, degreased with sodium chlorite and acetic acid, washed, dehemicellulosed, and then refined to produce fine fibrous cellulose (Patent Document 8). . In addition, a method has been proposed in which wood flour is used as a raw material, and the fiber is delignified with sodium chlorite and acetic acid, washed, dehemicellulose, enzymatically treated, and then refined into fine fibrous cellulose (Patent Document) 9). However, since sodium chlorite, which is a chlorine compound, is used, the lignin on the surface of the wood flour is efficiently removed, but the lignin inside the wood flour remains because of poor permeability, resulting in a YI value. It is difficult to obtain a fine fibrous cellulose having a low density, and since sodium chlorite is a chlorine compound, the wastewater after the reaction contains an organic chlorine compound, which causes environmental problems.

Akira Yamaguchi "Pulverization and Microfibrillation of Cellulose" Paper and Pulp Technology Times Vol. 28, No. 9, pp. 5 (1985) Tokuko Hayashi, Gen Shibuya “Cellulose Enzyme Refinement Method” Cellulose communications Vol. 16 (2), P73-78 (2009)

JP-A-6-10288 JP 2008-75214 A JP 2008-150719 A JP 2008-169497 A Special table 2009-526140 JP 2009-263850 A JP 2009-263849 A JP 2008-24788 A JP 2010-216021 A

  In the present invention, a fine fibrous cellulose having a fiber width of 1 nm to 1000 nm can be obtained in a simple method with a high yield by subjecting wood powder to chemical treatment, followed by enzyme treatment, and then mechanically refining. A method for forming a fine fibrous cellulose into a porous sheet is provided. In addition, when the sheet is impregnated with a polymer to form a composite, a composite having a low YI value before and after heating is provided.

  The present inventors performed treatment with cellulase enzymes after chemical treatment of bleaching wood flour with a bleaching agent such as degreased, delignified, dehemicellulose, and chlorine dioxide, followed by high-speed rotation type defibrating treatment or high pressure It has been found that fine fibrous cellulose having a fiber width of 1 nm to 1000 nm can be obtained in high yield by performing a finer treatment such as a homogenizer treatment, and further, the fine fibrous cellulose is made into a sheet and combined with a polymer. The inventors have also found that the YI value, which serves as an index for returning the color of the fine fibrous cellulose composite, can be lowered, and the present invention has been completed.

The present invention includes the following inventions.
(1) Wood chips are pulverized by pulverization, and the wood flour is degreased, delignified, dehemicellulose treated, bleached, and then treated with cellulase enzymes, using a high-speed rotary defibrator or high-pressure homogenizer It is a manufacturing method of the fine fibrous cellulose which refines.

(2) The method for producing fine fibrous cellulose according to (1), wherein the bleaching treatment is a chlorine dioxide bleaching treatment.

(3) In the delignification step, at least one selected from peracetic acid or a mixed solution of peracetic acid and persulfuric acid, or a Wise method using sodium chlorite and acetic acid is used. (1) or (2) This is a method for producing fine fibrous cellulose.

(4) Any of (1) to (3), wherein the addition rate of the cellulase enzyme is 0.1% by mass to 3% by mass relative to the solid content of the wood flour, and the treatment time with the enzyme is 30 minutes to 24 hours. The method for producing fine fibrous cellulose according to claim 1.

(5) A fine fibrous material obtained by adding an organic solvent to the fine fibrous cellulose aqueous dispersion produced by any one of the methods (1) to (4), papermaking and drying to obtain a porous cellulose sheet. It is a manufacturing method of a cellulose sheet.

(6) A fine fibrous cellulose composite obtained by impregnating a fine fibrous cellulose sheet produced by the method of (5) with a polymer.

  The inventors of the present invention have improved the yield of fine fibrous cellulose, made the fine fibrous cellulose sheet porous, and controlled the YI value before and after heating of the composite in which a polymer (matrix) is composited to the fine fibrous cellulose sheet. Various methods were studied. First, after degreasing, delignin, and dehemicellulose, chemical processing is performed on the wood powder from conifers and hardwoods, followed by high-speed rotary defibrator, high-pressure homogenizer defibator, ultrasonic defibrator, etc. At the same time, the yield of fine fibers obtained was high, but the YI value of the composite was low before heating, but increased after heating. A result that could satisfy both the yield of cellulose and the YI value before and after heating the composite was not obtained. Next, bleaching with chlorine dioxide after degreasing, delignification and dehemicellulose treatment, and fine fiberization by the method as described above, the yield of fine fibrous cellulose was significantly reduced, but the heating of the composite The front and rear YI values were greatly improved.

  The inventors of the present invention continued further diligent examination, and after the bleaching treatment such as the chlorine dioxide treatment or the like, the cellulase enzyme was used for the treatment, and then the fiber was refined by the method as described above. The inventors have found that fine fibrous cellulose can be obtained in a very high yield and that the YI value before and after heating of the composite can be controlled to be low, and the present invention has been completed.

  Although the mechanism by which the YI value after heat treatment, which is an index of the yield of fine fibers and the discoloration of the composite, has been dramatically improved, has not yet been fully elucidated, the present inventors have as follows. I am thinking. By subjecting the wood powder to the chemical treatment including chlorine dioxide, the wood resin, lignin and hemicellulose are sufficiently removed, and the enzyme is easily adsorbed on the purified cellulose fiber. Since the crystal part of the refined cellulose fiber is very strongly bonded, it is considered that the structure is destroyed mainly by the amorphous part due to the enzyme treatment. As a result, it is estimated that the crystallized portion of the cellulose fiber after the enzyme treatment becomes very large. In this way, when the cellulose fiber with the amorphous part decomposed is processed with a high-speed rotary defibrator or a high-pressure homogenizer, it is refined using the decomposed part as a trigger and easily has a fibrous width of nano-order. It is thought that can be obtained. In addition, the YI value of the composite was improved because the delignification was promoted by the addition of bleaching treatment such as chlorine dioxide, and the reducing end group of cellulose was oxidized to reduce the components contributing to fading. Guessed.

Hereinafter, the present invention will be described in detail.
In the present invention, when the cellulose fiber is refined, examples of the fiber raw material include plant-derived cellulose, animal-derived cellulose, and bacterial-derived cellulose. More specifically, wood-based paper such as softwood pulp and hardwood pulp is used. Pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw, bagasse, etc., or cellulose isolated from sea squirts and seaweed, etc. The raw material (wood chips) is preferably used after being powdered into wood. Examples of the wood flour include coniferous wood flour and hardwood wood flour, among which bay pine and eucalyptus are preferable. In particular, a raw material derived from a plantation tree of eucalyptus is a preferred embodiment because of the high uniformity of the material.

  Eucalyptus derived from planted trees that can be used in the present invention includes at least one material selected from globulas, grandis, camaldrensis, perita, saligna, danai, nightens, a hybrid of camaldrensis and eurofila, and the like. It is done.

  The wood chip as a fiber raw material used in the present invention is usually used for pulp production, for example, bay pine or eucalyptus chips (thickness 2 mm to 8 mm) are sun-dried or forcibly dried so that the moisture content is 10% or less. After drying with a machine, chips are pulverized in a pulverization process to produce wood flour. Here, although there is no restriction | limiting in particular in the particle size distribution of a chip | tip, since a thing with a thickness of 2-8 mm tends to be made into a wood powder, it is used suitably. If the moisture content of the chip exceeds 10%, the crystallinity of the final fine fibrous cellulose is greatly reduced, which is not preferable.

  In the production of wood flour in the present invention, the coarse pulverizer includes a shearing pulverizer such as a shredder and a cutter mill, a compression pulverizer such as a juicer crusher and a cone crusher, an impact pulverizer such as an impact crusher, or a roll mill and a stamp. It can be appropriately selected from among milling machines such as mills, edge runner mills, and rod mills in view of final use and cost. Here, it is not particularly necessary to adjust the particle diameter and shape, and therefore there is no problem even if pulverization is performed without using a screen.

  After coarse pulverization, the wood powder is finely pulverized without classification.For the fine pulverization, a self-pulverizing mill, a vertical roller mill, a high-speed rotary mill, a high-speed rotary mill with a built-in classifier, a container drive medium mill, There are a medium stirring mill, an airflow pulverizer, a compaction shear mill, a colloid mill, and the like, but an impact system in which powder is formed using a medium such as a ball or a rod made of zirconium, alumina, or SUS is preferable.

  In order to obtain the desired fine fibrous cellulose in the present invention, the wood flour is subjected to chemical treatment in the order of degreasing treatment, delignification treatment, dehemicellulose treatment, and bleaching treatment.

  In the degreasing treatment in the present invention, carbonate such as sodium carbonate, alcohol, alcohol, benzene which is a 1: 2 mixed solution, benzene, lipase which is an enzyme that decomposes fatty acid triglyceride, etc. can be used as appropriate. Examples include treatment at room temperature with stirring or high temperature and pressure, but it is inexpensive as a chemical, is not an organic solvent, can be used easily without using a pressure vessel, and has high degreasing efficiency. For this reason, the sodium carbonate method is preferred.

  As a method of delignification treatment, peracetic acid such as peracetic acid, persulfuric acid, percarbonate, perphosphoric acid, hypoperchloric acid, perbenzoic acid, metachloroperbenzoic acid, performic acid, perpropionic acid, etc. or chlorous acid and acetic acid In the present invention, a Wise method using peracetic acid, a mixture of peracetic acid and persulfuric acid, or a mixture of perchloric acid and acetic acid is also used for bleaching wood pulp and is relatively easy to handle. A method using any of the above is preferred. (In the following, chemicals such as peracetic acid may be referred to as delignifying agents.)

  Peracetic acid can be produced by acetylation of hydrogen peroxide or autooxidation of acetaldehyde, but the former method is preferred. The production method includes a method in which hydrogen peroxide and glacial acetic acid are reacted under sulfuric acid conditions or a method in which hydrogen peroxide and acetic anhydride are reacted. The former is called equilibrium peracetic acid, Although it is commercially available as peracetic acid, an example of its composition is 42% peracetic acid, 6% hydrogen peroxide, 37% acetic acid, 14% water, and 1% sulfuric acid. The latter is also called an in situ method, and examples of its composition are 23% peracetic acid and 8% hydrogen peroxide. Further, a distilled peracetic acid aqueous solution obtained by azeotropic distillation of the peracetic acid is also preferably used.

The persulfuric acid includes monopersulfuric acid (caroic acid) and dipersulfuric acid (marshall acid), and monopersulfuric acid is preferred from the viewpoint of effect and economy. Here, monopersulfuric acid can be produced by hydrolyzing peroxydisulfuric acid, or can be produced by mixing hydrogen peroxide and sulfuric acid at an arbitrary ratio, but the production method is particularly limited. It is not a thing. It is also possible to use something like oxone is a transient double sulfate _{(2KHSO 5 · KHSO 4 · K} 2 SO 4). However, in consideration of economy, it is a preferable embodiment to produce and use monopersulfuric acid by mixing high concentration hydrogen peroxide and high concentration sulfuric acid.

  A method for producing monopersulfuric acid by mixing high concentration hydrogen peroxide and high concentration sulfuric acid is 20 to 70% by mass, preferably 80 to 98% by mass in 35 to 60% by mass hydrogen peroxide water. Preferably, a method of dropping and mixing 93 to 96% by mass of concentrated sulfuric acid is preferable. The mixing molar ratio of the sulfuric acid and hydrogen peroxide is 1: 1 to 5: 1, preferably 2: 1 to 4: 1.

  In this invention, since YI value of the fine fibrous cellulose composite obtained can be made low by using the said acetic acid and persulfuric acid together, it is preferable embodiment.

  In the Wise method using peracetic acid alone, a mixture of peracetic acid and persulfuric acid, and chlorous acid and acetic acid, a concentration that can reduce the pH to 4 or less is preferable. The progress of the lignin reaction is accelerated, which is preferable. The blending ratio of the delignification agent to the defatted raw material is preferably 50% to 500%, and more preferably 90% to 250%. The temperature during delignification treatment is preferably 70 ° C to 99 ° C, more preferably 80 ° C to 98 ° C, and particularly preferably 90 ° C to 95 ° C. When the temperature is lower than 70 ° C., the efficiency of the delignification reaction is lowered, and the color is not preferable. On the other hand, if it exceeds 99 ° C., it becomes difficult to make fine fibers. The treatment time is preferably 0.5 to 2 hours for peracetic acid or a mixture of peracetic acid and persulfuric acid, and 4 to 6 hours for the Wise method.

  In the present invention, as the method for dehemicellulose formation, an aqueous solution of an alkali metal hydroxide is used for immersion treatment at room temperature overnight, or a short time treatment at a high temperature while stirring in the aqueous solution, or the aqueous solution. The method of processing under high temperature and high pressure while stirring in the inside is mentioned. Among them, potassium hydroxide is most preferable because it is inexpensive, can be used at normal temperature and pressure, and has high efficiency in dehemicellulose reaction.

  The wood powder (hereinafter abbreviated as pulp) that has been subjected to the dehemicellulose treatment is further bleached with an oxidizing bleaching agent or a reducing bleaching agent to remove residual lignin that has not been removed by the delignification treatment. Here, examples of the oxidizing bleaching agent include chlorine, hypochlorite, chlorine dioxide, hydrogen peroxide, oxygen, ozone, and peracetic acid. Examples of the reducing bleach include hydrosulfite, sodium borohydride, and thiourea dioxide. Among these bleaching agents, bleaching with chlorine dioxide is preferable because the delignification effect is high and the whiteness of the pulp can be maintained high. The addition amount of the bleaching agent is 0.1 to 10.0% by mass, preferably 0.5 to 5.0% by mass per pulp. Particularly in chlorine dioxide bleaching, the addition rate is 0.5 to 4.0% by mass, preferably 1.0 to 3.0% by mass, per pulp. The reaction pH is 2-6 after reaction, preferably 3-5. In order to adjust the pH, a known acid or alkali may be added before, immediately after, or simultaneously with the addition of chlorine dioxide. The addition method of chlorine dioxide may be added all at once or divided. The treatment temperature is 50 to 99 ° C., preferably 60 to 90 ° C., the treatment time is 30 to 360 minutes, preferably 60 to 240 minutes, and the pulp concentration during treatment is 1 to 40%, preferably 3 to 15%.

  In the present invention, the pulp dispersion is bleached as described above, and then treated with a cellulase enzyme. The cellulase enzyme that can be used in the present invention is an enzyme that cleaves β-1,4-glucoside bond of cellulose by hydrolysis and causes depolymerization. Examples of microorganisms that produce cellulase include aerobic bacteria, anaerobic bacteria, rumen bacteria present in the digestive organs of animals and insects, actinomycetes, yeast, and filamentous fungi (such as ascomycetes and basidiomycetes). , Each producing a variety of cellulases.

  Cellulase-based enzymes include the genus Trichoderma, the genus Acremonium, the genus Aspergillus, the genus Phanerochaete, the trametes, Trametes, Genus, Humicola (Bacteria), Bacillus (Bacteria), Suehirotake (Basidiomycetes), Streptomyces (Bacteria), Pseudomonas (Pseudomonas, Bacteria), etc. Enzymes. Such a cellulase enzyme can be purchased as a reagent or a commercial product. Examples thereof include cellulosin T2 (manufactured by HIPI), mecerase (manufactured by Meiji Seika Co., Ltd.), Novozyme 188 (manufactured by Novozyme), multifect CX10L (manufactured by Genencor), cellulase enzyme GC220 (manufactured by Genencor). Among these cellulase enzymes, filamentous fungal cellulase enzymes are preferred, and among the filamentous fungal cellulase enzymes, cellulase enzymes produced by Trichoderma bacterium (Trichoderma reesei or Hyporea jerorina) are cellulase enzymes. It is particularly preferred because of its wide variety of enzymes and high productivity.

  Cellulase enzymes are classified into a carbohydrate hydrolase family based on the higher order structure of the catalytic domain having a hydrolysis reaction function. On the other hand, cellulase enzymes are classified into endo-glucanase (EG) and cellobiohydrolase (CBH) according to cellulolytic properties. EG is highly hydrolyzable with respect to the amorphous part of cellulose, soluble cellooligosaccharides, and cellulose derivatives such as carboxymethylcellulose, and these molecular chains are randomly cut from the inside to lower the degree of polymerization. However, EG has low reactivity to crystalline cellulose microfibrils. In contrast, CBH decomposes the crystalline part of cellulose and gives cellobiose. CBH is hydrolyzed from the end of the cellulose molecule and is also called an exo-type or processive enzyme.

  In the present invention, both EG and CBH can be used as the cellulase enzyme. Each may be used alone, or EG and CBH may be mixed and used. Further, it may be used by mixing with a hemicellulase enzyme.

  The hemicellulase enzyme that can be used in the present invention is an enzyme that hydrolyzes hemicellulose. Among hemicellulase-based enzymes, xylanase, which is an enzyme that degrades xylan, mannanase, which is an enzyme that degrades mannan, and arabanase, an enzyme that degrades araban. In addition, pectinase, which is an enzyme that degrades pectin, can also be used as a hemicellulase-based enzyme. Microorganisms that produce hemicellulase enzymes often also produce cellulase enzymes.

  Hemicellulose is a polysaccharide excluding pectins between cellulose microfibrils in the plant cell wall. Hemicelluloses are diverse and differ between plant types and cell wall layers. In wood, glucomannan is the main component in the secondary wall of conifers, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwood. Therefore, in order to obtain fine fibrous cellulose from conifers, it is preferable to use mannase, and in the case of hardwoods, it is preferable to use xylanase.

  The amount of cellulase enzyme added to the pulp is preferably 0.1% by mass to 3% by mass, and more preferably 0.3% by mass to 2.5% by mass. If the addition amount is less than 0.1% by mass, the defibrating efficiency by the enzyme may decrease. If the amount exceeds 3% by mass, cellulose is saccharified and the yield of fine fibrous cellulose may be reduced.

  The pH of the pulp slurry during the cellulase enzyme treatment is preferably a pH of 3.0 to 6.9, which is a weakly acidic region, but an optimal pH region may be appropriately selected depending on the type of the cellulase enzyme. Further, the pH of the pulp slurry at the time of the hemicellulase enzyme treatment is preferably pH 7.1 to 10.0 which is a weak alkaline region, but an optimum pH region may be appropriately selected depending on the type of hemicellulase enzyme. The slurry temperature of the chemical pulp during treatment with the cellulase enzyme or hemicellulase enzyme is preferably 30 ° C to 70 ° C, more preferably 35 ° C to 65 ° C, and particularly preferably 40 ° C to 60 ° C. If the temperature is less than 30 ° C., the enzyme activity decreases and the treatment time becomes longer, which is not preferable. If the temperature exceeds 70 ° C., the enzyme is deactivated, which is not preferable. The treatment time is adjusted by the type of enzyme, temperature and pH, but treatment for 30 minutes to 24 hours is preferred. If the treatment time is less than 30 minutes, the effect of the enzyme treatment may hardly be exhibited. If it exceeds 24 hours, the decomposition of cellulose fibers proceeds too much by the enzyme, and the weighted average fiber length of the resulting fine fibrous cellulose may be too short.

  In addition, if the enzyme remains active, the decomposition of the cellulose fiber proceeds too much as described above, so 20% caustic soda in the pulp slurry after the reaction with the enzyme for a predetermined time has a pH of about 12. Usually, the enzyme is deactivated by adding the same, or the temperature of the pulp slurry is increased to 90 ° C. to deactivate the enzyme. Although it is simpler to add caustic soda, dehydration may be deteriorated in the subsequent washing stage, and it is necessary to deal with it. The washing with water is preferably carried out with 2 to 4 times as much water as the pulp, so that almost no enzyme remains.

  The pulp that has been subjected to the enzyme treatment is dispersed in water and subjected to a refining treatment as an aqueous suspension. The concentration of the aqueous suspension is preferably 0.1 to 3% by mass, and more preferably 0.3 to 1% by mass. Incidentally, if the concentration is less than 0.1% by mass, the effect of reducing the cellulose fibrillation load in the subsequent step may be almost lost. On the other hand, if the concentration exceeds 3% by mass, the viscosity increases excessively during the miniaturization process, and handling may become very difficult.

  As a method for defibrating pulp treated with a cellulase enzyme, a high-pressure homogenizer or a high-speed rotary defibrator is used. In the high-pressure homogenizer treatment, the pulp dispersion accelerated at high speed by pressurization is refined by rapid decompression, so the viscosity of the dispersion rises suddenly during the refinement process, and the pipes are clogged, or with excessive force. Since it is processed, it may be easy to shorten the fiber, so it is necessary to set processing conditions carefully. In addition, when the pressure under high pressure conditions is low or when the pressure difference from high pressure to reduced pressure conditions is small, the defibrating efficiency is lowered, and it is not preferable because a large number of repeated ejections are required to obtain a desired fiber width. . Furthermore, even when the pore diameter of the pores from which the cellulose fiber dispersion is ejected is too large, a sufficient fibrillation effect cannot be obtained, and in this case, even if the ejection treatment is repeated, the desired fiber width can be obtained. There is also a possibility that cellulose fibers cannot be obtained. The ejection of the cellulose fiber dispersion is repeated a plurality of times as necessary, thereby increasing the degree of fineness and obtaining cellulose fibers having a desired fiber width. The number of repetitions (pass number) is usually 1 or more, preferably 3 or more, and usually 20 or less, preferably 15 or less. As the number of passes increases, the degree of miniaturization can be increased. However, an excessively large number of passes is not preferable because the cost increases.

  Specific examples of such a high-pressure homogenizer include a “Starburst” manufactured by Sugino Machine, a “High-Pressure Homogenizer” manufactured by Izumi Food Machinery, and a homovalve-type high-pressure homogenizer typified by “Minilab 8.3H type” manufactured by Rannie. "Microfluidizer" manufactured by Microfluidics, "Nanomizer" manufactured by Yoshida Kikai Kogyo Co., Ltd., "Ultimizer" manufactured by Sugino Machine, "Genus PY" manufactured by Shiramizu Chemical Co., Ltd., "DeBEE2000" manufactured by BEE Japan And a chamber type high-pressure homogenizer.

  On the other hand, when a high-speed rotation type defibrator is used, a high shear rate can be generated by passing a narrow gap while rotating the pulp dispersion at a high speed. This is the most preferable embodiment because the crystallization treatment can be performed effectively. The high-speed rotation type defibrator is a type that disperses the pulp fiber to be treated by passing it through the gap between the rotating body and the fixed part. In general, the pulp fiber to be treated is passed through and dispersed in the gap between the inner rotator and the outer rotator. Examples of such a high-speed rotation type defibrator include “Clairemix” manufactured by M Technique, “TK Robotics” and “Filmix” manufactured by Primics, “Milder”, “Cabitron”, “Cabitron”, “ Sharp flow mill ".

  The fine fibrous cellulose obtained by the present invention is a cellulose fiber or rod-like particle that is much thinner than the pulp fiber usually used for papermaking. The fine fibrous cellulose is an aggregate of cellulose molecules including a crystal part, and its crystal structure is type I (parallel chain). The width of the fine fibrous cellulose is preferably 1 nm to 1000 nm as observed with an electron microscope, more preferably 2 nm to 500 nm, and still more preferably 4 nm to 100 nm. When the width of the fiber is less than 1 nm, since the cellulose molecule is dissolved in water, the physical properties (strength, rigidity, dimensional stability) as the fine fiber are not expressed. If it exceeds 1000 nm, it cannot be said that it is a fine fiber, and is merely a fiber contained in ordinary pulp, and physical properties (strength, rigidity, dimensional stability) as a fine fiber cannot be obtained. When the fine fibrous cellulose is used for transparency, the fine fiber width is preferably 50 nm or less. Composite materials obtained from these fine fibrous celluloses have high density and high density because they become dense structures, and in addition to obtaining high elastic modulus derived from cellulose crystals, there is little scattering of visible light High transparency is also obtained.

Using the fine fibrous cellulose obtained as described above, a fine fibrous cellulose sheet can be obtained. Thereby, the polymer can be impregnated or sandwiched between polymer sheets to form a fine fibrous cellulose composite. When producing a fine fibrous cellulose sheet by filtering defibrated cellulose fibers as a dispersion, the concentration of the dispersion used for filtration is preferably 0.05 to 1.0% by mass, and the concentration is too low. On the other hand, it takes an enormous amount of time for filtration. On the contrary, if the concentration is too high, a uniform sheet cannot be obtained, which is not preferable. When filtering the dispersion, it is important for the filter cloth at the time of filtration that the finely divided cellulose fibers do not pass through and the filtration rate is not too slow. As such a filter cloth, a sheet made of an organic polymer, a woven fabric, and a porous membrane are preferable. The organic polymer is preferably a non-cellulose organic polymer such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) or the like. Specific examples include a porous film of polytetrafluoroethylene having a pore size of 0.1 to 20 μm, for example, 1 μm, polyethylene terephthalate or polyethylene woven fabric having a pore size of 0.1 to 20 μm, for example, 1 μm.
Moreover, as a method for producing a sheet from an aqueous suspension containing fine fibrous cellulose, for example, a dispersion containing fine fibers described in Japanese Patent Application No. 2009-173136 is discharged onto the upper surface of an endless belt, and the discharged dispersion is discharged. A squeezing section for squeezing the dispersion medium from the squeezing medium to produce a web, and a drying section for drying the web to produce a fiber sheet, wherein the endless belt is disposed from the squeezing section to the drying section. And a method using a manufacturing apparatus in which the web generated in the water squeezing section is transported to the drying section while being placed on the endless belt.

  Examples of the dehydration method that can be used in the present invention include a dehydration method that is usually used in the manufacture of paper, and a method of dehydrating with a long net, circular net, inclined wire or the like and then dehydrating with a roll press is preferable. Examples of the drying method include methods used in paper manufacture. For example, methods such as a cylinder dryer, a Yankee dryer, hot air drying, and an infrared heater are preferable.

  The fine fibrous cellulose sheet can maintain various porosity depending on its production method. Examples of a method for obtaining a sheet having a large porosity include a method in which water in the sheet is finally replaced with an organic solvent such as alcohol in a film forming process by filtration. In this method, water is removed by filtration, and an organic solvent such as alcohol is added when the cellulose content reaches 5 to 99% by mass. Alternatively, the fine fibrous cellulose dispersion can be replaced by placing it in a filtration device and then gently pouring an organic solvent such as alcohol on top of the dispersion. In the case of obtaining a composite by impregnating a fine fibrous cellulose sheet with a polymer, if the porosity is small, the polymer is difficult to be impregnated, and therefore there is a porosity of 10% by volume or more, preferably 20% by volume or more. It is preferable. The organic solvent such as alcohol used here is not particularly limited, but alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethylene glycol, and ethylene glycol mono-t-butyl ether are used. In addition to these, one or more organic solvents such as acetone, methyl ethyl ketone, tetrahydrofuran, cyclohexane, toluene, carbon tetrachloride and the like can be mentioned. In the case of using a water-insoluble organic solvent as the organic solvent, it is preferable to use a water-soluble organic solvent or a water-soluble organic solvent and then replace it with a water-insoluble organic solvent.

  As a method for controlling the porosity, a method in which a solvent having a boiling point higher than that of the alcohol is mixed and dried at a temperature lower than the boiling point of the solvent can be mentioned. In this case, if necessary, the high boiling point solvent remaining after drying is replaced with another solvent, and then the polymer is impregnated. The cellulose fiber sheet from which the solvent has been removed by filtration is then dried, but in some cases, it may proceed to the next step without drying. That is, when the fine fibrous cellulose which is the heat-treated dispersion is filtered and then impregnated with the polymer, the polymer can be impregnated as it is without passing through the drying step. Also, when the defibrated cellulose fibers that are the dispersion liquid are filtered and the sheet is heat-treated, it can also be carried out without a drying step.

  However, drying is also preferable in terms of controlling the porosity, film thickness, and strengthening the sheet structure. This drying may be air drying, vacuum drying, pressure drying, or heat drying. When heating, the temperature is preferably 80 ° C to 150 ° C. If the heating temperature is too low, drying may take time or drying may be insufficient. Conversely, if the heating temperature is too high, the cellulose fiber sheet may be colored or cellulose may be decomposed. Moreover, when pressurizing, 0.1-1 Mpa is preferable. If the pressure is too low, drying may be insufficient. If the pressure is too high, the planar structure of cellulose may be crushed or cellulose may be decomposed. Although there is no limitation in particular in the thickness of a fine fibrous cellulose sheet, Preferably it is 1 micrometer or more, More preferably, it is 5 micrometers or more. Moreover, it is 1000 micrometers or less normally, Preferably it is 5-250 micrometers.

  The fine fibrous cellulose composite of the present invention is a composite of the fine fibrous cellulose sheet obtained above and a polymer (= matrix material) other than cellulose. Here, the matrix material refers to a polymer material or a precursor thereof (for example, a monomer) that is bonded to a cellulose fiber sheet, fills a void, or kneads granulated cellulose fiber particles. Suitable for this matrix material are thermoplastic resins that become fluid when heated, thermosetting resins that polymerize by heating, light that is polymerized and cured by irradiation with ultraviolet rays, electron beams, etc. (active Energy beam) At least one kind of resin (polymer material) or a precursor thereof (so-called monomer or oligomer) from curable resin or the like. A fine fibrous cellulose composite can be obtained by impregnating a precursor of such a thermosetting resin or photocurable resin into a sheet of fine fibrous cellulose, and polymerizing and curing by heating or light.

  In the present invention, among the following matrix materials (polymer materials or precursors thereof), in the case of a polymer material or precursor, the polymer is an amorphous compound having a high glass transition temperature (Tg). What is a polymer is preferable for obtaining a highly durable fine fibrous cellulose composite having excellent transparency. Among these, the degree of amorphousness is preferably 10% or less, particularly 5% or less in terms of crystallinity, and Tg is preferably 110 ° C. or more, particularly 120 ° C. or more, and particularly preferably 130 ° C. or more. When Tg is low, there is a risk of deformation when touched with, for example, hot water, which causes a practical problem.

  In the present invention, matrix materials other than cellulose to be combined with the fine fibrous cellulose sheet are exemplified below, but the matrix material used in the present invention is not limited to the following. That is, the thermoplastic resin includes styrene resin, acrylic resin, aromatic polycarbonate resin, aliphatic polycarbonate resin, aromatic polyester resin, aliphatic polyester resin, aliphatic polyolefin resin, and cyclic olefin resin. And polyamide resins, polyphenylene ether resins, thermoplastic polyimide resins, polyacetal resins, polysulfone resins, and amorphous fluorine resins. Examples of thermosetting resins include precursors such as epoxy resins, acrylic resins, oxetane resins, phenol resins, urea resins, melamine resins, unsaturated polyester resins, silicon resins, polyurethane resins, diallyl phthalate resins. Furthermore, examples of the thermoplastic resin include precursors such as an epoxy resin, an acrylic resin, and an oxetane resin exemplified in the description of the thermosetting resin.

As a method for compositing the fine fibrous cellulose sheet and the matrix material (polymer), the following methods (a) to (g) are preferably exemplified.
(A) A method of polymerizing by impregnating a fine fibrous cellulose sheet with a liquid thermoplastic resin precursor (b) Polymerization by impregnating a fine fibrous cellulose sheet with a thermosetting resin precursor or a photocurable resin precursor Method of curing (c) A resin solution (containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor) in a fine fibrous cellulose sheet (Solution) After drying by impregnating with a solution, a method of adhering with a heating press or the like and polymerizing and curing as necessary (d) impregnating a fine fibrous cellulose sheet with a thermoplastic resin melt and adhering with a heating press or the like Method (e) A method in which thermoplastic resin sheets and fine fibrous cellulose sheets are alternately arranged and adhered with a heating press or the like (f) on one side or both sides of the fine fibrous cellulose sheet (G) A resin solution (thermoplastic resin, heat on a single or both sides of a fine fibrous cellulose sheet) by applying a polymer-like thermoplastic resin precursor, a thermosetting resin precursor or a photocurable resin precursor to polymerize and cure. By applying a solution containing at least one solute selected from a plastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor, removing the solvent, and then polymerizing and curing as necessary. How to combine

  The curable composition for forming the fine fibrous cellulose composite of the present invention can be polymerized and cured by a known method. Among them, a simple method includes thermal curing, radiation curing, and the like. Among radiation curing, photocuring is preferable. In particular, light having a wavelength of about 200 nm to 450 nm is preferable, and ultraviolet light having a wavelength of 250 to 400 nm is more preferable. Specifically, a method in which a thermal polymerization initiator that generates radicals upon heating is added to the curable composition in advance and polymerized by heating (hereinafter sometimes referred to as “thermal polymerization”), the curable composition in advance. A method of adding a photopolymerization initiator that generates radicals by radiation such as ultraviolet rays to polymerize by irradiating with radiation (hereinafter sometimes referred to as “photopolymerization”), and a thermal polymerization initiator and a photopolymerization initiator Can be added in advance and polymerized by a combination of heat and light. Photopolymerization is more preferred in the present invention.

  As the photopolymerization initiator, a photo radical generator typified by benzophenone is usually used. These photopolymerization initiators may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, when the total amount of radically polymerizable compounds in the curable composition is 100 parts by mass. . The upper limit is usually 1 part by mass or less, preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less. If the amount is too large, the polymerization proceeds rapidly, not only increasing the birefringence of the resulting cured product, but also the hue.

The amount of radiation to be irradiated upon curing is arbitrary as long as the photopolymerization initiator generates radicals. However, when the amount is extremely small, the polymerization is incomplete, so that the cured product has sufficient heat resistance and mechanical properties. If it is not expressed and, on the contrary, extremely excessive, it causes deterioration due to light such as yellowing of the cured product, so that ultraviolet rays having a wavelength of 300 to 450 nm are used in accordance with the composition of the monomer and the type and amount of the photopolymerization initiator. preferably irradiated with 0.1 J / cm ² or 200 J / cm ² or less. More preferably, irradiation is performed in the range of 1 J / cm ² or more and 20 J / cm ² . More preferably, the radiation is divided into a plurality of times. That is, when the first irradiation is performed for about 1/20 to 1/3 of the total irradiation amount and the necessary remaining amount is irradiated for the second and subsequent times, a cured product with smaller birefringence is obtained. Specific examples of the ultraviolet lamp to be used include a metal halide lamp, a high pressure mercury lamp, an ultraviolet LED lamp, and the like.

  A laminate can also be obtained by stacking a plurality of the cellulose fiber composites thus produced. In that case, you may laminate | stack the polymer sheet | seat which does not contain the composite_body | complex containing a cellulose fiber. Or in order to join cellulose composites or a polymer sheet and a cellulose composite, you may apply | coat an adhesive agent or interpose an adhesive sheet. Moreover, it can also integrate by adding a heat press process to a laminated body.

  Examples are given below to explain the present invention in more detail, but it goes without saying that the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

<Example 1>
[Chip processing]
After classifying bay pine to be used for pulp production into chips with a thickness of 8 mm and a 2 mm-on chip with a thickness of 8 mm, the moisture content of the chips (the amount of moisture / the total amount of chips including the amount of moisture) is reduced to the sun. The sample was adjusted to 10% and used as a wood powder sample.

[Wood powdering (coarse and fine)]
The chip was coarsely pulverized using a coarse pulverizer (model TYM-600-350-WS) manufactured by Toyo Hydraulic Co., Ltd. Without classifying it, using a CD mill (model CD-30 type) manufactured by Chuo Kakoh Co., Ltd., which uses rods in two stages as the grinding media, the average particle size is about 100 μ to 250 μ, The processing time was changed and pulverized.

[Degreasing process]
The wood flour (BD 15 g) was treated at 90 ° C. for 5 hours with stirring in a 2% aqueous sodium carbonate solution. The treated raw material was washed with 10 times the amount of distilled water, dehydrated with a Buchner, and distilled water was added to adjust the concentration.

[Delignification step with peracetic acid]
A mixture of acetic anhydride and 30% hydrogen peroxide in a volume ratio of 1: 1 was prepared, and this amount was equivalent to 4.5% in terms of hydrogen peroxide equivalent to the degreased wood flour (BD 15 g). And treated at 90 ° C. for 1 hour. The treated wood flour was washed with 10 times the amount of distilled water, dehydrated with Buchner, and distilled water was added to adjust the concentration.

[Dehemicellulose process]
The slurry-like delignified wood powder (BD 15 g) was immersed in a 5% aqueous potassium hydroxide solution at room temperature for 24 hours for treatment. After the treatment, it was washed with 10 times the amount of distilled water and dehydrated with a Buchner.

[Chlorine dioxide bleaching]
Prepare wood powder (hereinafter pulp) treated with dehemicellulose to a concentration of 15%, add chlorine dioxide water to make 3% chlorine dioxide (relative to dry materials), and hold at 80 ° C. for 2 hours. Processed. After the treatment, it was washed with 10 times the amount of distilled water and dehydrated with a Buchner.

[Enzyme treatment]
Cellulase enzyme “GC220” (manufactured by Genencor) was added to 1.0% aqueous suspension of the obtained chlorine dioxide bleached pulp at a rate of 1.0% with respect to the pulp solid content, and 50 ° C. For 1 hour. After the treatment, the enzyme was inactivated by adjusting the pH to 12 using a 10% sodium hydroxide solution. Thereafter, it was washed with 10 times the amount of distilled water and dehydrated with a Buchner. Thereafter, distilled water was added to obtain a 0.5% aqueous suspension.

[Refining treatment and yield measurement]
The above suspension is defibrated for 30 minutes at 21,500 rpm ("Creamix" manufactured by MTechnic Co., Ltd.) using a high-speed defibrator (fine processing) to obtain a fine fibrous cellulose aqueous suspension. It was. The supernatant concentration of this suspension was measured. Furthermore, about the said fine fibrous cellulose aqueous suspension, it processed for 10 minutes at about 12,000 G using a centrifuge ("H-200NR" by Kokusan Co., Ltd.), measured the supernatant liquid concentration, The yield was determined from the calculation formula.
Yield (%) = (Concentration of supernatant after centrifugation) ÷ (Slurry concentration after refinement) × 100

[Measurement of fine fibrous cellulose fiber width]
The fiber width of the fine fibrous cellulose in the supernatant obtained by centrifugation was measured by electron microscope observation as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05 to 0.1% by mass is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to obtain a sample for TEM observation. Observation with an electron microscope image was performed at a magnification of 5000 times, 10000 times, or 50000 times depending on the width of the constituent fibers. At this time, the sample and the observation conditions (magnification, etc.) were set so that 20 or more fibers intersected the axis at least with respect to the axis when assuming an axis of arbitrary image width in the obtained image. With respect to an observation image that satisfies this condition, two vertical and horizontal axes were drawn per image, and the fiber width of the fibers intersecting with the axis was visually read. In this way, images of at least three non-overlapping surface portions were observed with an electron microscope, and the fiber width values of fibers intersecting each other with two axes were read (at least 20 × 2 × 3 = 120 fiber widths). .

[Preparation of porous fine fibrous cellulose sheet]
The supernatant obtained by centrifugation was suction filtered on a membrane filter having a pore size of 0.45 μm to prepare a wet sheet. 2400% (absolute dry raw material) of ethylene glycol mono-t-butyl ether (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 118, boiling point 152 ° C.) was added on the obtained wet sheet, and suction filtration was performed again. Thereafter, drying was performed in two stages using a cylinder dryer (90 ° C.) and an oven (130 ° C.) to prepare a 40 g / m ² sheet.

[Measurement of pore volume and pore surface area]
The pore volume and pore surface area of 1 μm diameter or less of the fine fibrous cellulose sheet were measured with a mercury porosimeter (manufactured by Shimadzu Corporation, trade name: “Autopore IV9505”) to evaluate the porosity. The larger this value, the better the polymer impregnation. The pore volume is preferably 0.1 mL / g or more and 2 mL / g or less. If it is less than 0.1 mL / g, impregnation is impossible, and if it exceeds 2 mL / g, the ratio of fine fibrous cellulose to the polymer to be impregnated is unfavorable. The pore surface area is preferably 40 m ² / g or more and 200 m ² / g or less. When it is less than 40 m ² / g, the impregnation property of the polymer is deteriorated, and when it exceeds 200 m ² / g, the strength of the sheet is undesirably lowered.

[Preparation of fine fibrous cellulose resin composite]
The fine fibrous cellulose sheet was mixed with 100 parts by mass of 1,10-decanediol diacrylate, 0.02 parts by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASC “Lucirin TPO”), benzophenone 0 The mixed solution was impregnated with 0.01 parts by mass and left under reduced pressure overnight. The fine fibrous cellulose aggregate impregnated with the resin solution was sandwiched between two glass plates, and was cured with an ultraviolet ray using an electrodeless mercury lamp (“D bulb” manufactured by Fusion UV Systems). Conditions of UV curing, irradiation intensity 400 mW / cm ^2, is semi-cured through the front and back twice in total to the line speed 7m / min, then irradiation intensity 1900mW / cm ^2, front and back each twice at a line speed of 2m / min (total 4 times) under conditions of complete curing. After UV curing, the glass plate was removed to obtain a fine fibrous cellulose composite.

[Measurement of YI value of fine fibrous cellulose composite]
The YI value before heating of the fine fibrous cellulose composite was measured using a color computer manufactured by Suga Test Instruments. Moreover, it heat-processed for 4 hours in 200 degreeC oven (nitrogen gas atmosphere), and measured the YI value after a heating. A large YI value indicates strong coloring.

  Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating, measured as described above.

<Example 2>
The fine fibrous cellulose, fine fibrous cellulose sheet and composite of the present invention were obtained in the same manner as in Example 1 except that the Wise method was used in the delignification step and a high-pressure homogenizer was used in the defibrating treatment. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

[Delignin process by Wise method]
The degreased wood powder was suspended in 1.8 L of water, 2.4 mL of acetic acid was added with stirring, 12 g of sodium chlorite was added, and the mixture was treated at 80 ° C. for 1 hour. The pH at that time was 4.0. After this operation was repeated five times, the raw material was washed and adjusted in concentration in the same manner as after the peracetic acid treatment.

[Miniaturization processing]
A 0.5% pulp suspension was treated with a high-pressure homogenizer ("Starburst System" manufactured by Sugino Machine Co., Ltd.). Used and repeated 12 times.

<Example 3>
The fine fibrous cellulose and fine fibrous material of the present invention were used in the same manner as in Example 1 except that a eucalyptus tree planted at the age of 8 years was used as the material and a mixed solution of peracetic acid and persulfuric acid in the delignification step was used. Cellulose sheets and composites were obtained. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

[Delignining step with peracetic acid and persulfuric acid mixture]
100% by mass of acetic acid, 98% by mass of sulfuric acid and 60% by mass of hydrogen peroxide were mixed at a ratio of 1: 1.5: 1 (molar ratio). An amount corresponding to 4.5% in terms of hydrogen peroxide equivalent was added to the raw material after degreasing treatment (BD 15 g), and treated at 90 ° C. for 1 hour. After the treatment, washing and concentration adjustment were performed in the same manner as after the peracetic acid treatment.

<Example 4>
The fine fibrous cellulose, fine fibrous cellulose sheet and composite of the present invention were obtained in the same manner as in Example 3 except that peracetic acid was used in the delignification step and a high-pressure homogenizer was used in the defibrating treatment. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

[Delignification step with peracetic acid]
A mixture of acetic anhydride and 30% hydrogen peroxide in a volume ratio of 1: 1 was prepared, and this amount was equivalent to 4.5% in terms of hydrogen peroxide equivalent to the degreased wood flour (BD 15 g). And treated at 90 ° C. for 1 hour. The treated wood flour was washed with 10 times the amount of distilled water, dehydrated with Buchner, and distilled water was added to adjust the concentration.

[Miniaturization processing]
A 0.5% pulp suspension was treated with a high-pressure homogenizer ("Starburst System" manufactured by Sugino Machine Co., Ltd.). Used and repeated 12 times.

<Example 5>
The fine fiber of the present invention was the same as in Example 3 except that bleaching was performed with hypochlorous acid (pH 9.5, addition rate 2%, temperature 60 ° C., time 2 hours) instead of chlorine dioxide in the bleaching step. Cellular cellulose, fine fibrous cellulose sheet and composite were obtained. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

<Comparative Example 1>
A fine fibrous cellulose, a fine fibrous cellulose sheet and a composite were obtained in the same manner as in Example 1 except that the bleaching treatment and the enzyme treatment were not performed. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

<Comparative example 2>
A fine fibrous cellulose, a fine fibrous cellulose sheet and a composite were obtained in the same manner as in Example 2 except that chlorine dioxide was used for delignification treatment and no bleaching treatment was performed. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.
The same method was used. The results are shown in Table 1.

<Comparative Example 3>
A fine fibrous cellulose, a fine fibrous cellulose sheet and a composite were obtained in the same manner as in Example 3 except that the enzyme treatment was not applied and the hot water treatment was performed (50 ° C., 6 hours). Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

<Comparative example 4>
A fine fibrous cellulose, a fine fibrous cellulose sheet and a composite were obtained in the same manner as in Example 4 except that a blender was used in the refining treatment. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

[Miniaturization processing]
In the blender stirring process, Vita Mix (R) Corp. The fiber was defibrated for 15 minutes at 37,000 rpm with "ABS-BU" manufactured by the company.

<Comparative Example 5>
A fine fibrous cellulose, a fine fibrous cellulose sheet and a composite were obtained in the same manner as in Example 5 except that the enzyme treatment was performed without the chlorine dioxide treatment after the dehemicellulose treatment. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

<Comparative Example 6>
A fine fibrous cellulose composite was obtained in the same manner as in Example 1 except that ethylene glycol mono-t-butyl ether was not added on the fine fibrous wet sheet. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

<Comparative Example 7>
A fine fibrous cellulose composite was obtained in the same manner as in Example 4 except that ethylene glycol mono-t-butyl ether was not added on the fine fibrous wet sheet. Table 1 shows the fiber width, yield, pore volume of 1 μm or less, YI value before heating, and YI value after heating measured in the same manner as in Example 1.

  As is apparent from Table 1, it can be seen that fine fibrous cellulose having a high yield and a low YI value can be obtained with the fine fibrous cellulose composite by the method for producing fine fibrous cellulose of the present invention.

  By the production method of the present invention, fine fibrous cellulose having a fiber width of 1 nm to 1000 nm can be obtained with high yield. Furthermore, since the YI value before and after heating of the transparent composite material obtained by impregnating and curing the polymer resin into the sheet made of fine fibrous cellulose is very low, it is flexible for organic EL and liquid crystal displays with little fading. Useful as a transparent substrate.

Claims (6)

  Wood chips are pulverized into wood powder, and the wood powder is degreased, delignified, dehemicellulose treated, bleached, treated with cellulase enzymes, and refined with a high-speed rotary defibrator or high-pressure homogenizer. The manufacturing method of the fine fibrous cellulose characterized by performing.   The method for producing fine fibrous cellulose according to claim 1, wherein the bleaching treatment is a chlorine dioxide bleaching treatment.   The at least one selected from the Wise method using peracetic acid or a mixed solution of peracetic acid and persulfuric acid, or sodium chlorite and acetic acid is used in the delignification step. A method for producing fine fibrous cellulose according to 1.   The addition rate of the cellulase enzyme is 0.1% by mass to 3% by mass with respect to the solid content of the wood flour, and the treatment time with the enzyme is 30 minutes to 24 hours. The manufacturing method of the fine fibrous cellulose of any one.   An organic solvent is added to the fine fibrous cellulose aqueous dispersion produced by the method according to any one of claims 1 to 4, and papermaking is performed to obtain a porous cellulose sheet. A method for producing a fine fibrous cellulose sheet.   A fine fibrous cellulose composite obtained by impregnating a polymer into a fine fibrous cellulose sheet produced by the method according to claim 5.