JP5626222B2 - Method for producing fine fibrous cellulose sheet and composite in which fine fibrous cellulose sheet is impregnated with resin - Google Patents

Description

The present invention relates to a method for producing a fine fibrous cellulose sheet that efficiently converts fine fibrous cellulose into a porous sheet, and a composite obtained by impregnating a porous fine fibrous cellulose sheet obtained by the production method with a resin. The purpose is to provide a body.
This application claims priority on December 10, 2009 based on Japanese Patent Application No. 2009-280209 for which it applied to Japan, and uses the content here.

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, a transparent paper (glassine paper) can be obtained by processing (beating, pulverizing) cellulose fibers with a refiner, kneader, sand grinder, etc., and then making the cellulose fibers fine (microfibril). 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 having a high elastic modulus and a low coefficient of thermal expansion, and heat resistant dimensional stability is increased by combining the cellulose fibers with a resin, so that they are used for laminates and the like. However, ordinary cellulose fibers are aggregates of crystals and have a limit in dimensional stability due to fibers having a cylindrical void.
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 diffusely reflected white and becomes highly opaque. However, when the fine fibrous cellulose sheet is impregnated with a 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. For this reason, when combined with a resin, fine fibers are more uniformly and densely dispersed in the resin, and the heat-resistant dimensional stability is dramatically increased. Moreover, since the fibers are thin, the transparency is high. The composite of fine fibrous cellulose 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, the aqueous dispersion of fine fibrous cellulose has a concentration of 1% by mass and a viscosity of about 500 to 10000 mPa · sec. When the dispersion is dehydrated to form a sheet, the drainage of the dispersion is extremely poor. The papermaking speed is extremely slow, and industrial production by winding (continuous sheet) is difficult. The reason why the production speed at the time of paper making is extremely slow is that the freeness (dehydration rate) of fine fibrous cellulose is very low.
There are many disclosures about the fine fiber technology and the composite technology with resin, but most of the technology to make the fine fiber cellulose porous sheet while maintaining industrial productivity. The current situation is not.

  Specifically, Patent Documents 1 to 3 disclose a technique for making cellulose fibers into fine fibers. However, disclosure of the technique for improving the drainage when forming cellulose into fine fibers is also suggested. Nor.

  Patent Documents 4 to 10 disclose a technique for improving physical properties such as mechanical strength by complexing fine fibrous cellulose with a polymer resin, but a technique for facilitating complexation (for example, cellulose). However, there is almost no disclosure of a technique that makes it easy to impregnate resin.

  Patent Documents 10 to 20 disclose a technique for forming fine fibrous cellulose into a sheet, but have not yet achieved an industrial level of productivity, and the fine fibrous cellulose is made porous. Therefore, it is desired to provide a simple method for making the sheet.

  In Patent Document 21, a sheet prepared by adding a slurry of fine fibrous cellulose so that the solid content falls within a range of 6% by mass or more and 30% by mass or less is replaced with an organic solvent or a mixed solution of water and an organic solvent and then dried. However, the productivity is at a low level even with the above method.

JP-A 56-1000080 JP 2008-169497 A Japanese Patent No. 3036354 Japanese Patent No. 3641690 JP 9-509694 A JP 2006-316253 A JP-A-9-216952 JP-A-11-209401 JP 2008-106152 A JP-A-2005-060680 JP-A-8-188981 JP 2006-193858 A JP 2008-127893 A JP-A-5-148387 JP 2001-279016 A JP 2004-270064 A JP-A-8-188980 JP 2007-23218 A JP 2007-23219 A Japanese Patent Laid-Open No. 10-248872 JP 2008-308547 A

  The present invention has been made in view of the above circumstances, and is a method for producing a fine fibrous cellulose sheet that efficiently converts fine fibrous cellulose into a porous sheet, and a fine fibrous cellulose sheet obtained by the production method. A composite obtained by impregnating a resin is provided.

  The present inventors applied an organic solvent to or impregnated a sheet obtained by filtering and dewatering an aqueous dispersion of fine fibrous cellulose, and drying the sheet containing moisture and the organic solvent. It was found that voids were generated and the resin was easily impregnated, and the present invention was completed based on this finding.

The present invention includes the following inventions.
(1) In the method for producing a fine fibrous cellulose sheet, a dispersion step of dispersing fine fibrous cellulose in water, the dispersion obtained in the dispersion step is dehydrated by filtration on a porous substrate, and contains moisture Paper making process for forming a sheet, applying an organic solvent to the sheet containing moisture, organic solvent treatment process for forming a sheet containing moisture and an organic solvent, drying for drying the sheet containing the moisture and the organic solvent The manufacturing method of the fine fibrous cellulose sheet which has a process and the organic solvent used at an organic-solvent process process is 120-260 degreeC of boiling points, and is water-soluble.

(2) The manufacturing method of the fine fibrous cellulose sheet as described in (1) which mix | blends a cellulose coagulant with a dispersion liquid in the said dispersion | distribution process.

(3) The method for producing a fine fibrous cellulose sheet according to (2), wherein the cellulose coagulant is at least one selected from inorganic salts or an organic compound containing a cationic functional group.

(4) The method for producing a fine fibrous cellulose sheet according to (2) or (3), wherein the cellulose coagulant is at least one selected from ammonium hydrogen carbonate, ammonium carbonate, aluminum sulfate, and polyamide-based fine cationic resin.

(5) The method for applying the organic solvent is at least one method selected from a spray coater, a curtain coater, a gravure coater, a bar coater, a blade coater, and a size press coater (1) to (4) 2. A method for producing a fine fibrous cellulose sheet according to item 1.

(6) The organic solvent applied to the moisture-containing sheet is diluted with water, and the mass ratio of the organic solvent to water is 100: 1 to 100: 1000, and any one of (1) to (5) The manufacturing method of the fine fibrous cellulose sheet of description.

(7) The drying process includes any one of (1) to (6) including a two-stage drying process in which water is evaporated in the first drying process and then the organic solvent is evaporated in the second drying process. Method for producing a fine fibrous cellulose sheet.

(8) The fine fibrous form according to any one of (1) to (7), wherein a mass ratio of water and the organic solvent contained in the sheet containing the water and the organic solvent is 100: 10 to 10: 100. A method for producing a cellulose sheet.

(9) The method for producing a fine fibrous cellulose sheet according to any one of (1) to (8), wherein the organic solvent is a glyme.

(10) The method for producing fine fibrous cellulose according to any one of (1) to (9), wherein the organic solvent is diethylene glycol dimethyl ether.

(11) The method for producing a fine fibrous cellulose sheet according to any one of (1) to (10), wherein the fine fibrous cellulose has a fiber width of 2 to 1000 nm.

(12) The manufacturing method of the fine fibrous cellulose sheet of any one of (1)-(11) whose density | concentration in the dispersion liquid of the said fine fibrous cellulose is 0.1-1 mass%.

(13) A fine fibrous cellulose composite obtained by impregnating a fine fibrous cellulose sheet obtained by the production method according to any one of (1) to (12) with a resin.

  According to the present invention, a production method capable of very efficiently producing a porous sheet of fine fibrous cellulose, and a composite having excellent physical properties obtained by impregnating a resin into the fine fibrous cellulose sheet obtained by the production method Can be provided.

Hereinafter, the present invention will be described in detail.
The fine fibrous cellulose in the present invention is a cellulose fiber or rod-like particle that is much narrower than the pulp fiber usually used in papermaking. Fine fibrous cellulose is an aggregate of crystalline cellulose molecules, and its crystal structure is type I (parallel chain). The width of the fine fibrous cellulose is preferably 2 nm to 1000 nm, more preferably 2 nm to 500 nm, still more preferably 4 nm to 100 nm as observed with a transmission electron microscope. When the width of the fiber is less than 2 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. Moreover, when it is a use as which transparency is calculated | required by the composite of a fine fibrous cellulose, as for the width | variety of a fine fiber, 50 nm or less is preferable.

The fiber length (length-weighted average fiber length measured according to JAPAN TAPPI paper pulp test method No. 52: 2000) in the present invention is preferably 1-1000 μm, more preferably 10-600 μm, and 50 -300 micrometers is especially preferable. The aspect ratio, which is a value obtained by dividing the fiber length by the fiber width, is preferably 100 to 30000, more preferably 500 to 15000, and particularly preferably 1000 to 10,000.
When the length weighted average fiber length is less than 1 μm, the strength for forming the sheet is remarkably low, so that the sheet cannot be formed. When the fiber length is 10 μm or more, the sheet can be formed reliably. When the fiber length is 50 μm or more, the sheet is further easily formed and the strength of the obtained sheet is improved. When trying to create a fiber whose length-weighted average fiber length exceeds 1000 μm and the fiber width is 1 μm or less, it is necessary to reduce the fiber width so that the fiber is not cut as much as possible (so that the length-weighted average fiber length is not shortened). However, such treatment requires mechanical treatment with a weak shearing force for a long time, and industrial production is difficult.
When the aspect ratio is less than 100, when the length weighted average fiber length is 50 μm or more, there is no significant difference in the physical properties of the obtained sheet compared to normal pulp fibers (with an aspect ratio of about 50), and the fiber width is If the thickness is reduced to the order of 10 nm, the fiber length is shortened, making it difficult to form a sheet, and the strength is significantly lowered.

  Here, the fact that the fine fibrous cellulose has a type I crystal structure is that 2θ = 14 in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418４) monochromatized with graphite. It can be identified by having typical peaks at two positions near -17 ° and 2θ = 22-23 °.

  There are no particular restrictions on the method for producing fine fibrous cellulose, but mechanical actions such as grinders (stone mill type grinders), high-pressure homogenizers, ultra-high pressure homogenizers, high-pressure collision type grinders, disk type refiners, conical refiners, etc. are used. A method of thinning the cellulosic fibers by wet pulverization is preferred. Further, it may be refined after chemical treatment such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy radical) oxidation, enzyme treatment, ozone treatment and the like. Examples of cellulosic fibers to be refined include plant-derived cellulose, animal-derived cellulose, and bacterial-derived cellulose. More specifically, it is isolated from wood-based paper pulp such as conifer pulp and hardwood pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, sea squirt and seaweed. A cellulose etc. are mentioned. Among these, wood-based paper pulp and non-wood pulp are preferable in terms of easy availability.

In the present invention, the fine fibrous cellulose is used by being dispersed in water. The fine fibrous cellulose aqueous dispersion is prepared by adding water to a container and then adding fine fibrous cellulose while stirring. In this dispersion step, a cellulose coagulant is preferably blended.
Using an apparatus such as an agitator, a homomixer, or a pipeline mixer as a stirring device, cellulose is uniformly dispersed. In this case, the concentration of the dispersion is preferably 0.1 to 1% by mass, and more preferably 0.2 to 0.8% by mass. If the concentration of the dispersion is less than 0.1% by mass, the papermaking efficiency may be lowered. If it exceeds 1% by mass, the viscosity may be too high and handling may be difficult. The viscosity of the dispersion is preferably about 100 to 5000 mPa · s as a B-type viscosity at 25 ° C.

  Examples of the cellulose coagulant that can be used in the present invention include water-soluble inorganic salts and water-soluble organic compounds containing a cationic functional group. Water-soluble inorganic salts include sodium chloride, calcium chloride, potassium chloride, ammonium chloride, magnesium chloride, aluminum chloride, sodium sulfate, potassium sulfate, aluminum sulfate, magnesium sulfate, sodium nitrate, calcium nitrate, sodium carbonate, potassium carbonate, ammonium carbonate Examples thereof include sodium phosphate and ammonium phosphate.

  Examples of the water-soluble organic compound containing a cationic functional group include polyacrylamide, polyvinylamine, urea resin, melamine resin, melamine-formaldehyde resin, and a polymer obtained by polymerizing or copolymerizing a monomer containing a quaternary ammonium salt.

  The blending amount of the cellulose coagulant needs to be blended more than the amount that the aqueous dispersion is gelled. Specifically, it is preferable to blend 0.5 to 10 parts by mass of a cellulose coagulant with respect to 100 parts by mass of fine fibrous cellulose. Incidentally, when the blending amount of the cellulose coagulant is less than 0.5 parts by mass, the gelation of the aqueous dispersion becomes insufficient, and the drainage improvement effect may be poor. If the blending amount exceeds 10 parts by mass, gelation may proceed excessively and handling of the aqueous dispersion may be difficult. More preferably, it is the range of 1-8 mass parts. Here, the gelation according to the present invention is a state change in which the viscosity of the aqueous dispersion increases rapidly and greatly and loses fluidity. However, the gel obtained here is jelly-like and easily broken by stirring. Judgment of gelation can be visually judged because it is in a state of rapidly losing fluidity, but the concentration is 0.5 mass% and the temperature is 25 ° C. for the aqueous dispersion of fine fibrous cellulose containing the cellulose coagulant of the present invention. Judging from the B-type viscosity (rotor No. 4, rotational speed 60 rpm). The viscosity is preferably 1000 mPa · second or more, more preferably 2000 mPa · second or more, and particularly preferably 3000 mPa · second or more. Incidentally, if the B-type viscosity is less than 1000 mPa · s, gelation of the aqueous dispersion becomes insufficient, and the effect of improving drainage may be poor.

For applications where transparency is required for the fine fibrous cellulose sheet, it is preferable to use a compound having a weak cationic property as the cellulose coagulant. Examples of compounds having weak cationic properties include ammonium carbonate compounds such as ammonium carbonate and ammonium hydrogen carbonate, and organic carboxylate ammonium compounds such as ammonium formate, ammonium acetate, and ammonium propionate. Among these, ammonium carbonate and ammonium hydrogen carbonate which are decomposed and vaporized by heating at 60 ° C. or higher and released from the sheet are preferable.
Furthermore, slightly cationic organic polymers such as polyamide compounds, polyamide polyurea compounds, polyamine polyurea compounds, polyamidoamine polyurea compounds, and polyamidoamine compounds can also be used.
Moreover, about the said compound with weak cationicity, it is preferable that the compounding quantity of a cellulose coagulant is 10-200 mass parts of cellulose coagulants with respect to 100 mass parts of fine fibrous cellulose, More preferably, 20- It is 150 mass parts, More preferably, it is the range of 30-100 mass parts. When the blending amount of the weakly cationic cellulose coagulant is less than 10 parts by mass, the drainage may be deteriorated. On the contrary, if the blending amount exceeds 200 parts by mass, the transparency may deteriorate.

  As a method for forming a sheet that can be used in the present invention, a method usually used in papermaking is preferable, and a method of dehydrating with a long net, circular net, inclined wire, etc. and then dewatering with a roll press can be mentioned. Moreover, as a drying method, the method normally used by paper manufacture is preferable, For example, methods, such as a cylinder dryer, a Yankee dryer, hot air drying, an infrared heater, are mentioned.

  In addition, as a porous base material which can be used as a wire at the time of dehydration, a wire used for general papermaking can be mentioned. Examples thereof include metal wires such as stainless steel and bronze, and plastic wires such as polyester, polyamide, polypropylene, and polyvinylidene fluoride. Moreover, you may use membrane filters, such as a cellulose acetate base material, as a wire. The opening of the wire is preferably 0.2 to 200 μm, and more preferably 0.4 to 100 μm. If the mesh opening is less than 0.2 μm, the dehydration rate becomes extremely slow, which is not preferable. If it exceeds 200 μm, the yield of fine fibrous cellulose decreases, which is not preferable. In the present specification, “dehydration” refers to reducing the water content to an arbitrary value, and “drying” refers to a state in which a liquid is removed and dried (15% by mass or less as moisture, preferably 10 mass% or less). The water content after dehydration is preferably 60 to 95 parts, more preferably 70 to 90 parts, relative to 100 parts of the wet sheet. In order to reduce the water content to less than 60 parts, it is necessary to make the dehydration zone very long, and as the water content decreases, dehydration becomes difficult. If the water content exceeds 95 parts, it is not preferable because it takes too much time in the drying process or the wet sheet is too fluid to maintain its shape.

  Among these, 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 (wire), and a dispersion medium is squeezed from the discharged dispersion to generate a web. And a drying step of drying the web to produce a fiber sheet, the endless belt is disposed from the squeezing step to the drying step, and the web generated in the squeezing step is the endless It is preferable to use a manufacturing method or the like that is transported to the drying step while being placed on a belt.

In this invention, it is necessary to apply | coat an organic solvent to the said fine fibrous cellulose sheet containing a water | moisture content, and as the organic solvent, it is necessary for the boiling point to be 120-260 degreeC, and to be water-soluble. The purpose of applying the organic solvent in the present invention is to impregnate the fine fibrous cellulose sheet with the organic solvent and evaporate (dry) the water and the organic solvent to obtain a porous sheet.
When the boiling point of the organic solvent is lower than 120 ° C., the amount of the organic solvent that evaporates increases when water is evaporated, which causes a problem that a porous sheet cannot be obtained. On the other hand, when the boiling point exceeds 260 ° C., a high temperature is required to evaporate the organic solvent, causing problems such as yellowing of the fine fibers and a decrease in fiber strength. Further, the solubility in water is preferably 10% or more at 20 ° C., more preferably 30% or more, and still more preferably 50% or more.

  Examples of such organic solvents include glycol ethers such as dipropylene glycol methyl ether, ethylene glycol monobutyl ether, ethylene glycol mono t-butyl ether, and diethylene glycol monoethyl ether; diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, Glymes such as triethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol isopropyl methyl ether; dihydric alcohols such as 1,2-butanediol and 1,6 hexanediol; diethylene glycol monoethyl ether Acete DOO, ethylene glycol monomethyl ether acetate. Two or more of these organic solvents may be used in combination. Further, these organic solvents may contain water.

  Of these, diethylene glycol dimethyl ether and diethylene glycol isopropyl methyl ether are particularly preferable because they are excellent in solubility in water and have a good balance of boiling point, surface tension, and molecular weight.

  The organic solvent may be diluted with water and replaced with water in the sheet containing moisture by coating or impregnating the organic solvent. By diluting the organic solvent with water, the porosity (pore volume, pore surface area, etc.) of the resulting fine fibrous cellulose sheet can be controlled. When the mixing ratio of water is small, the pore volume, pore surface area, and pore diameter of the fine fibrous cellulose sheet are increased. Also. When the mixing ratio of water is large, the pore volume, pore surface area, and pore diameter of the fine fibrous cellulose sheet are reduced. The mass ratio of the organic solvent to water is preferably 100: 1 to 100: 1000, more preferably 100: 2 to 100: 750, and particularly preferably 100: 5 to 100: 500. If the water mass ratio is less than 1, the effect of dilution with water may be lost. If the mass ratio of water exceeds 1000, the fine fibrous cellulose sheet may not be porous. Further, by diluting the organic solvent with water, the used organic solvent and / or water can be recovered and reused.

  In the present invention, the mass ratio of water and the organic solvent contained in the fine fibrous cellulose sheet containing the water and the organic solvent is preferably 100: 10 to 10: 100, more preferably 100: 30 to 30: 100, 100: 50 to 50: 100 is more preferable. If the ratio of the organic solvent is less than 10, the porosity of the sheet may decrease. On the other hand, when the ratio of the organic solvent exceeds 100, the pulp concentration is too low and the papermaking efficiency is lowered. Moreover, when the ratio of the organic solvent exceeds 100 with the pulp concentration kept constant, the viscosity may be too high, or the fine fibers may aggregate.

  In the present invention, the organic solvent is applied as a spray coater, curtain coater, gravure coater, bar coater, blade coater, size press coater, gate roll coater, cap coater, micro gravure coater, die coater, rod coater, comma coater. There are methods such as screen coater, but it is selected from spray, curtain, gravure, bar, blade, size press because it is easy to control the application amount (impregnation amount) of organic solvent and can apply (impregnation) uniformly. It is preferable to use at least one method. A sheet containing moisture is weak in strength, and when it comes into contact with the coater head, the sheet may be streaked or unevenness may occur. Therefore, a spray or curtain which is a non-contact coating method is most preferable.

  In the present invention, the drying process is not particularly limited, but a two-stage drying is a preferred embodiment. That is, water is evaporated in the first drying step, and then an organic solvent having a boiling point higher than that of water is evaporated in the second drying step. Moreover, as a drying method, the method normally used by paper manufacture is preferable, For example, methods, such as a cylinder dryer, a Yankee dryer, hot air drying (floating dryer), an infrared heater, are mentioned. Many fine voids are formed in the fine fibrous cellulose sheet obtained by this method, and it is extremely easy to impregnate the resin. As a measure of the porosity of the sheet, the air permeability measured according to JIS P 8117: 1998 is about 50 to 3000 seconds / 100 cc.

The basis weight of the fine fibrous cellulose sheet obtained in the present invention is preferably 0.1~1000g / ^{m 2,} more preferably ^{1~500g / m 2, 5~100g / m} 2 is particularly preferred. When the basis weight is less than 0.1 g / m ² , the sheet strength becomes extremely weak and continuous production cannot be performed. If it exceeds 1000 g / m ² , dehydration takes a very long time and productivity is extremely lowered, which is not preferable.

  The thickness of the fine fibrous cellulose sheet obtained in the present invention is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, and particularly preferably 5 to 100 μm. When the thickness is less than 0.1 μm, the sheet strength becomes extremely weak and continuous production cannot be performed. If it exceeds 1000 μm, dehydration takes a very long time, and productivity is extremely lowered, which is not preferable.

The density of fine fibrous cellulose sheet obtained in the present invention is preferably 0.10~1.5g / cm ^3, more preferably ^{0.30~1.20g / cm 3, 0.40~0.80g / cm} 3 Is particularly preferred. When the density is less than 0.10 g / cm ³ , the sheet strength becomes weak, which is not preferable. If it exceeds 1.5 g / cm ³ , there will be almost no voids, which is not preferable when combined with a resin or the like. Here, the density can be controlled by a dehydrating pressure during paper making, a pressing pressure, a calendar process after sheet formation, and the like. The density of the present invention is a value obtained by dividing the basis weight by the thickness.

  Examples of the resin that can be combined with the fine fibrous cellulose in the present invention include at least one resin selected from thermoplastic resins, thermosetting resins, photocurable resins, and resin cured products.

  As thermoplastic resins, styrene resins, acrylic resins, aromatic polycarbonate resins, aliphatic polycarbonate resins, aromatic polyester resins, aliphatic polyester resins, aliphatic polyolefin resins, cyclic olefin resins, polyamides Resin, polyphenylene ether resin, thermoplastic polyimide resin, polyacetal resin, polysulfone resin, amorphous fluorine resin and the like.

  Styrenic resin refers to homopolymers of vinyl aromatic monomers or copolymers with other monomers, and examples of vinyl aromatic monomers include styrene, α-methylstyrene, paramethylstyrene, etc. Among them, a homopolymer of styrene or a copolymer with other monomers is preferable. In the case of a homopolymer, it may be one having stereoregularity in the chain (isotactic, syndiotactic) or one having no stereoregularity (atactic). Other monomers that can be copolymerized include acrylonitrile, methacrylonitrile, isoprene, butadiene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl acetate, acrylic monomers and styrene. Resin obtained by copolymerizing with a monomer, for example, acrylonitrile-styrene copolymer, styrene-methacrylic acid copolymer, etc., can adjust the refractive index of the resin by the copolymerization ratio. This is preferable. For example, when a monomer of polystyrene (refractive index: about 1.59) and a monomer of polyacrylonitrile (refractive index: about 1.52) are copolymerized at 71:21, a resin having a refractive index of about 1.57 Is obtained. Examples of the form of the copolymer include a block copolymer, a random copolymer, and a graft copolymer.

  Acrylic resins include methacrylic acid alkyl esters such as cyclohexyl methacrylate, t-butyl cyclohexyl methacrylate, and methyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, and the like. One or more monomers selected from acrylic acid alkyl esters are polymerized. Of these, a homopolymer of methyl methacrylate or a copolymer with other monomers is preferable. Examples of monomers copolymerizable with methyl methacrylate include other alkyl methacrylates; acrylic acid alkyl esters; aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene, acrylonitrile, and methacrylonitrile. Vinyl cyanides such as; maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide; unsaturated carboxylic acid anhydrides such as maleic anhydride; and unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic acid It is done. Moreover, alicyclic acrylic resins, such as tricyclodecyl methacrylate, are also mentioned.

  The aromatic polycarbonate resin is an aromatic polycarbonate derived from an aromatic dihydroxy compound. Examples of the aromatic dihydroxy compound include 1,1-bis (4-hydroxy-t-butylphenyl) propane, 2, Bis (hydroxyaryl) alkanes such as 2-bis (4-hydroxyphenyl) propane; Bis (1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, etc. Hydroxyaryl) cycloalkanes; dihydroxyaryl ethers such as 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dimethylphenyl ether; 4,4′-dihydroxydiphenyl sulfide, 4,4 ′ -Dihydroxy-3,3'- Dihydroxyaryl sulfides such as methylphenyl sulfide; dihydroxyaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethylphenyl sulfoxide; 4,4′-dihydroxydiphenyl sulfone; Examples include dihydroxyaryl sulfones such as 4,4′-dihydroxy-3,3′-dimethylphenylsulfone. Among these, 2,2-bis (4-hydroxyphenyl) propane (common name, bisphenol A) is particularly preferable. These aromatic dihydroxy compounds can be used alone or in combination of two or more.

The aromatic polyester resin is not particularly limited, but specific examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyarylate, and the like.
Examples of the aliphatic polyester resin include a polymer mainly composed of aliphatic hydroxycarboxylic acid and a polymer mainly composed of aliphatic polycarboxylic acid and aliphatic polyhydric alcohol. Specifically, polymers having aliphatic hydroxycarboxylic acid as a main constituent component include polyglycolic acid, polylactic acid, poly (3-hydroxybutyric acid), poly (4-hydroxybutyric acid), poly (4-hydroxyyoshido). Herbic acid), poly (3-hydroxyhexanoic acid), polycaprolactone, and the like. Polymers mainly composed of aliphatic polycarboxylic acid and aliphatic polyhydric alcohol include polyethylene adipate, polyethylene succinate, poly Examples include butylene adipate and polybutylene succinate.

Aliphatic polyolefin resins include polyethylene, polypropylene, ethylene-propylene copolymers, polymethylpentene, polybutene, ethylene-vinyl acetate copolymers, ionomer resins (ethylene-acrylic acid polymer salts and styrene-sulfonates). And the like, and copolymers thereof, modified products with maleic acid, and the like.
The cyclic olefin resin is a polymer containing a cyclic olefin skeleton in a polymer chain, such as norbornene or cyclohexadiene, or a copolymer containing these, and the production method thereof is not particularly limited. Examples of the cyclic olefin-based resin include norbornene-based resins composed of a repeating unit of a norbornene skeleton or a copolymer of a norbornene skeleton and a methylene skeleton. “Arton” manufactured by JSR, “ZEONEX” manufactured by Nippon Zeon Co., Ltd. And “Zeonoa”, “Appel” manufactured by Mitsui Chemicals, and “Topas” manufactured by Chicona.

  The polyamide resin is not particularly limited as long as it is a known polyamide resin. For example, polycaprolactam (nylon 6), polytetramethylene adipamide (nylon 4,6), polyhexamethylene adipamide (nylon 6,6), polyhexamethylene sebacamide (nylon 6,10), polyhexa Methylene dodecamide (nylon 6,12), polyundecamethylene adipamide (nylon 1,16), polyundecalactam (nylon 11), polydodecalactam (nylon 12), polytrimethylhexamethylene terephthalamide (nylon TMHT ), Polyhexamethylene isophthalamide (nylon 6I), polynonanemethylene terephthalamide (9T), polyhexamethylene terephthalamide (6T), polybis (4-aminocyclohexyl) methane dodecamide (nylon PACM12), polybis (3-methyl) -Aminocyclohexyl) methane dodecamide (nylon dimethyl PACM12), polymetaxylylene adipamide (nylon MXD6), polyundecamethylene hexahydroterephthalamide (nylon 11T (H)), polydodecane terephthalamide (nylon 12T), and Among these, polyamide copolymers containing at least two different polyamide-forming components, and mixtures thereof.

Examples of the polyphenylene ether resin include poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), and poly (2-methyl-6). -Phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether) and the like, and copolymers of 2,6-dimethylphenol and other phenols (for example, A polyphenylene ether copolymer such as a copolymer with 2,3,6-trimethylphenol or a copolymer with 2-methyl-6-butylphenol as described in JP-B-52-17880. Can be mentioned.
Among these, particularly preferred polyphenylene ethers include poly (2,6-dimethyl-1,4-phenylene ether), a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, or these It is a mixture. In addition, the polyphenylene ether resin that can be used in the present invention may be a polyphenylene ether modified in whole or in part. The modified polyphenylene ether here means at least one carbon-carbon double bond or triple bond and at least one carboxylic acid group, acid anhydride group, amino group, hydroxyl group, or glycidyl in the molecular structure. The polyphenylene ether modified with at least one modifying compound having a group. Since the polyphenylene ether resin has high heat resistance and excellent electrical characteristics, it can be suitably used for high heat resistance applications and electronic parts.

The monomer in the present invention refers to a monomer constituting these thermoplastic resins. The number average molecular weight of these thermoplastic resins is generally 1000 or more, preferably 5000 or more and 5 million or less, and more preferably 10,000 or more and 1 million or less. Particularly when impregnated with the monomer and polymerized by polymerization, the compounding of the monomer that forms a cross-linked structure with another monomer such as divinylbenzene also improves the plasticity at high temperature. It is extremely effective in terms of suppression.
These thermoplastic resins can be used alone or in admixture of two or more. In the case of using a mixture of two or more thermoplastic resins, it is preferable because the refractive index of the resin can be adjusted by the mixing ratio. A resin obtained by blending an acrylic resin and a styrene resin is preferable. For example, polymethyl methacrylate (refractive index: about 1.49) and acrylonitrile-styrene copolymer (acrylonitrile content: about 21%, refractive index: about 1) .57) are mixed at 50:50 to give a resin with a refractive index of about 1.53.

In addition, the thermosetting resin and the photocurable resin used in the present invention are relatively low molecular weight substances that are liquid, semi-solid or solid at room temperature and exhibit fluidity at room temperature or under heating. means. These can be an insoluble and infusible resin formed by forming a network-like three-dimensional structure while increasing the molecular weight by causing a curing reaction or a crosslinking reaction by the action of a curing agent, a catalyst, heat or light. The resin cured product in the present invention means a resin obtained by curing the thermosetting resin or the photocurable resin.
The thermosetting resin used in the present invention is not particularly limited, but specific examples include epoxy resin, thermosetting modified polyphenylene ether resin, thermosetting polyimide resin, urea resin, allyl resin, Silicon resin, benzoxazine resin, phenol resin, unsaturated polyester resin, bismaleimide triazine resin, alkyd resin, furan resin, melamine resin, polyurethane resin, aniline resin, etc. Examples thereof include resins obtained by mixing seeds or more. Among these, an epoxy resin, an allyl resin, an unsaturated polyester resin, a vinyl ester resin, a thermosetting polyimide resin, and the like are suitable for use as an optical material because they have transparency.

  The epoxy resin refers to an organic compound having at least one epoxy group. The number of epoxy groups in the epoxy resin is preferably 1 to 7 per molecule, more preferably 2 or more per molecule. Here, the number of epoxy groups per molecule is determined by dividing the total number of epoxy groups in the epoxy resin by the total number of molecules in the epoxy resin. It does not specifically limit as said epoxy resin, A conventionally well-known epoxy resin can be used, For example, the epoxy resin etc. which were shown below are mentioned. These epoxy resins may be used independently and may use 2 or more types together. These epoxy resins are thermosetting resin precursor epoxy compounds, and by using a curing agent, a cured epoxy resin that is a cured product of the epoxy resin can be obtained.

  For example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin and bisphenol S type epoxy resin; novolak type epoxy resins such as phenol novolac type epoxy resin and cresol novolak type epoxy resin; Aromatic epoxy resins such as trisphenol methane triglycidyl ether and hydrogenated products and brominated products thereof can be mentioned. Also, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexanecarboxylate, bis (3,4 -Epoxycyclohexyl) adipate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (3,4-epoxycyclohexyl-5,5-spiro- Examples include alicyclic epoxy resins such as 3,4-epoxycyclohexanone-metadioxane and bis (2,3-epoxycyclopentyl) ether.

  Also, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether Aliphatic epoxy resins such as glycidyl ether, polyglycidyl ether of a long-chain polyol containing a polyoxyalkylene glycol having 2 to 9 carbon atoms (preferably 2 to 4 carbon atoms) or a polytetramethylene ether glycol, etc. It is done. Also, glycidyl ester type epoxies such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, diglycidyl-p-oxybenzoic acid, salicylic acid glycidyl ether-glycidyl ester, dimer acid glycidyl ester, etc. Examples thereof include resins and hydrogenated products thereof. Further, triglycidyl isocyanurate, N, N′-diglycidyl derivative of cyclic alkylene urea, N, N, O-triglycidyl derivative of p-aminophenol, N, N, O-triglycidyl derivative of m-aminophenol, etc. Examples thereof include glycidylamine type epoxy resins and hydrogenated products thereof. Moreover, the copolymer etc. of radical polymerizable monomers, such as glycidyl (meth) acrylate, ethylene, vinyl acetate, (meth) acrylic acid ester, etc. are mentioned. In the present invention, (meth) acryl means acryl or methacryl.

  Moreover, the thing which epoxidized the double bond of the unsaturated carbon in the polymer mainly based on conjugated diene compounds, such as epoxidized polybutadiene, or the polymer of the partially hydrogenated thing is mentioned. Also, a polymer block mainly composed of a vinyl aromatic compound such as epoxidized SBS (styrene butadiene styrene) and a polymer block mainly composed of a conjugated diene compound or a polymer block of a partially hydrogenated product thereof are the same. Examples thereof include epoxidized unsaturated carbon double bonds of conjugated diene compounds in a block copolymer in the molecule. Moreover, the polyester resin etc. which have 1 or more, preferably 2 or more epoxy groups per molecule are mentioned. Examples thereof include urethane-modified epoxy resins and polycaprolactone-modified epoxy resins in which a urethane bond or a polycaprolactone bond is introduced into the structure of the epoxy resin. Examples of the modified epoxy resin include rubber modified epoxy resins in which the epoxy resin contains a rubber component such as NBR (Nitrile Butadiene Rubber), CTBN (Carboxyl-Terminated Butadiene-Nitral Rubber), polybutadiene, and acrylic rubber. It is done. In addition to the epoxy resin, a resin or oligomer having at least one oxirane ring may be added.

Moreover, the thermosetting resin and composition containing a fluorene group, such as a fluorene containing epoxy resin, a fluorene containing acrylate resin, a fluorene containing epoxy acrylate resin, or its hardened | cured material is also mentioned. These fluorene-containing epoxy resins are suitably used because they contain a fluorene group in the molecule and thus have a high refractive index and high heat resistance.
The curing agent used for the curing reaction of the epoxy resin is not particularly limited, and conventionally known curing agents for epoxy resins can be used. For example, amine compounds, compounds such as polyaminoamide compounds synthesized from amine compounds, A tertiary amine compound, an imidazole compound, a hydrazide compound, a melamine compound, an acid anhydride, a phenol compound, a heat latent cationic polymerization catalyst, a photolatent cationic polymerization initiator, dicyanamide, and derivatives thereof are exemplified. These hardening | curing agents may be used independently and 2 or more types may be used together.

Moreover, as a photocurable resin used in this invention, the epoxy resin containing a photolatent cationic polymerization initiator etc. are mentioned, for example. These thermosetting resins or photocurable resins may be used alone or in combination of two or more.
In addition, when hardening the said photocurable resin, you may apply heat simultaneously with light irradiation. In the present invention, the curing agent and curing catalyst used in combination with the thermosetting resin and the photocurable resin are not particularly limited as long as they are used for curing the thermosetting resin and the photocurable resin. Specific examples of the curing agent include polyfunctional amines, polyamides, acid anhydrides, and phenol resins. Specific examples of the curing catalyst include imidazole. These may be used alone or as a mixture of two or more. it can.

  The polyimide resin in the present invention is not particularly limited, but is a resin containing an imide group in the main chain skeleton, and any of thermoplastic and thermosetting polyimide resins can be used. Specific examples include polyimide, polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, and the like.

  Moreover, resin obtained by mixing 2 or more types of thermoplastic resins, thermosetting resins, photocurable resins, and resin cured products can also be used.

In the present invention, as a method of compounding the resin for the fine fibrous cellulose sheet,
(1) A method in which a monomer is impregnated and polymerized,
(2) A method of impregnating and curing a thermosetting resin precursor or a photocurable resin precursor,
(3) A method of drying after impregnating the resin solution,
(4) A method of producing a composite by any one of the methods of impregnating a thermoplastic resin melt of the resin and cooling after defoaming can be used.

(1) A method of impregnating and polymerizing a monomer is a method of impregnating a fine fibrous cellulose sheet with a monomer such as methyl methacrylate, which is a monomer constituting a thermoplastic resin, and performing the above process by heat treatment or the like. It is a production method for obtaining a composite comprising a fine fibrous cellulose sheet and the resin by polymerizing a monomer. In the production method, an organic peroxide such as peroxide or a polymerization catalyst generally used for polymerization of monomers can be used as a polymerization initiator. When it is assumed that the polymerization catalyst impairs the performance of the composite as an impurity, impregnate a high-purity monomer that does not contain any polymerization inhibitor such as quinones, and heat without using a polymerization initiator. Polymerization is also effective.

(2) The method of impregnating and curing a thermosetting resin precursor or a photocurable resin precursor is to finely mix a thermosetting resin precursor such as an epoxy resin or a photocurable resin precursor and a curing agent. By impregnating the fibrous cellulose sheet and curing the thermosetting resin precursor or the photocurable resin precursor by heat treatment or light irradiation, heat of the fine fibrous cellulose sheet and the cured epoxy resin that is the resin, etc. This is a production method for obtaining a composite comprising a cured product of a curable resin or a cured product of a photocurable resin. When the thermosetting resin precursor such as epoxy resin or the photocurable resin precursor is solid at room temperature and it is difficult to impregnate the fine fibrous cellulose sheet, the precursor is heat-treated and melted in advance. It is also possible to impregnate a solution obtained by dissolving the precursor in a soluble solvent. For the purpose of enhancing the smoothness of the surface, it is also effective to further advance the reaction by applying a heat press treatment when the curing reaction has progressed to some extent. It is also effective at the time of increasing the film thickness to stack and treat several composites that have undergone a certain degree of curing reaction during the heat treatment.

(3) The method of drying after impregnating the resin solution is to dissolve the thermoplastic resin in a dissolvable solvent, impregnate the fine fibrous cellulose sheet, and dry it to heat the fine fibrous cellulose sheet. This is a manufacturing method in which a plastic resin is combined.

(4) The method of impregnating a thermoplastic resin melt as the resin and cooling it after defoaming is a method in which the thermoplastic resin is plasticized or melted by heat treatment at a glass transition temperature or higher or at a melting point or higher to form fine fibers. It is a production method for obtaining a composite comprising a fine fibrous cellulose sheet and a thermoplastic resin by impregnating the cellulose sheet and cooling after defoaming. The heat treatment is desirably performed under pressure, and the use of equipment having a vacuum heating press function is effective.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to these Examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

<Adjustment Example 1: Fine fibrous cellulose A>
After adding 1150 parts by mass of water to 100 parts by mass of NBKP pulp (Oji Paper Co., Ltd., moisture 50% freeness 600 mLcsf) and defibrating with a disintegrator, the pulp concentration was adjusted to 2-3% and treated with a refiner. The freeness of the pulp treated with the refiner was 300 mLcsf. Water is added to the pulp treated with the refiner so that the pulp concentration is between 0.5 and 0.7%, and using a stone mill type disperser ("Supermass colloider" manufactured by Masuko Sangyo Co., Ltd., stone mill type G). The slurry was processed 5 times to obtain a slurry A of fine fibrous cellulose. The pulp concentration of the slurry was adjusted to 0.5%. When the width of the fine fibrous cellulose was observed and measured with a scanning electron microscope (SEM), the width of the fiber was in the range of 200 to 800 nm.

<Adjustment Example 2: Fine fibrous cellulose B>
The fine fibrous cellulose A was treated 10 times with a high-pressure collision type disperser (“Ultimizer” manufactured by Sugino Machine Co., Ltd.) to obtain a slurry of fine fibrous cellulose B. When the width of the fine fibrous cellulose was observed and measured with a scanning electron microscope (SEM), the width of the fiber was in the range of 100 to 300 nm.

<Adjustment Example 3: Fine fibrous cellulose C>
The fine fibrous cellulose A was treated 20 times with a high-pressure collision type disperser (“Ultimizer” manufactured by Sugino Machine Co., Ltd.) to obtain a slurry of fine fibrous cellulose C. When the width of the fine fibrous cellulose was observed and measured with a scanning electron microscope (SEM), the width of the fiber was in the range of 50 to 200 nm.

<Adjustment Example 4: Fine fibrous cellulose D>
150 parts by weight of water and 4 parts by weight of NBKP pulp (moisture 50% freeness 600 mLcsf manufactured by Oji Paper Co., Ltd.) and 2,25,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) 0.025 parts by weight and odor To a water dispersion prepared by sequentially adding 0.25 parts by mass of sodium chloride with stirring, a 13% by mass aqueous solution of sodium hypochlorite was added to 1 g of absolute dry pulp so that the amount of sodium hypochlorite was 2 The reaction was started by adding 0.5 mmol. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10.5. The pulp obtained by filtering and washing the reaction product was added with water so that the concentration became 1.5% to obtain a pulp dispersion. The obtained pulp dispersion was defibrated for about 5 minutes with a disintegrator to obtain fine fibrous cellulose D. The concentration of the slurry was adjusted to 0.5%. When the width | variety of the said fine fibrous cellulose was observed and measured with the transmission electron microscope (TEM), the width | variety of the fiber was the range of 3-20 nm.

<Example 1>
A wet sheet was prepared while decompressing the fine fibrous cellulose A of Preparation Example 1 on a 500 mesh polyester mesh. The wet sheet had a solid content of 10%. On the obtained wet sheet, 100 parts of diethylene glycol dimethyl ether (DEGDME) (manufactured by Toho Chemical Co., Ltd., trade name: “High Solve MDM”, molecular weight 134, boiling point 162 ° C., surface tension 28 N / m) with respect to 100 parts of the wet sheet. It was uniformly applied by spraying. A spray spray type was used. The pressure was further reduced to form a wet sheet containing water and an organic solvent. The wet sheet had a solid content of 10%. The ratio of water and organic solvent contained in the wet sheet was 50/50. The wet sheet was dried together with a 500 mesh polyester mesh with a cylinder roll for 3 minutes at 80 ° C. so that the wet sheet was in contact with the mirror surface to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and wet. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The obtained sheet was white and opaque and had a thickness of 50 μm.

<Example 2>
A fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that 30 parts of diethylene glycol dimethyl ether was blended. The obtained sheet was white and opaque, and the thickness was 39 μm.

<Example 3>
A fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that 60 parts of diethylene glycol dimethyl ether was blended. The obtained sheet was white and opaque and had a thickness of 41 μm.

<Example 4>
A fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that 200 parts of diethylene glycol dimethyl ether was blended. The obtained sheet was white and opaque and had a thickness of 58 μm.

<Example 5>
35 g / m ² fine fibrous cellulose as in Example 1 except that the organic solvent was applied to the surface of the wet sheet using a gravure roll (50 mesh, lattice, forward coating) instead of spray coating. A sheet was obtained. The coating amount of the organic solvent was 30 parts with respect to 100 parts of the wet sheet. The obtained sheet was white and opaque, and the thickness was 37 μm.

<Example 6>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that an organic solvent was applied to the surface of the wet sheet using a curtain coater instead of spray coating. The coating amount of the organic solvent was 100 parts with respect to 100 parts of the wet sheet. The obtained sheet was white and opaque and had a thickness of 51 μm.

<Example 7>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that the organic solvent was applied to the surface of the wet sheet using a bar coater instead of spray coating. The coating amount of the organic solvent was 100 parts with respect to 100 parts of the wet sheet. The obtained sheet was white and opaque and had a thickness of 48 μm.

<Example 8>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that the organic solvent was applied to the surface of the wet sheet using a blade coater instead of spray coating. The coating amount of the organic solvent was 100 parts with respect to 100 parts of the wet sheet. The obtained sheet was white and opaque, and the thickness was 47 μm.

<Example 9>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that the organic solvent was applied to the surface of the wet sheet using a size press instead of spray coating. The coating amount of the organic solvent was 100 parts with respect to 100 parts of the wet sheet. The obtained sheet was white and opaque, and the thickness was 45 μm.

<Example 10>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 4 except that the fine fibrous cellulose B of Preparation Example 2 was used. The obtained sheet was white and opaque, and the thickness was 49 μm.

<Example 11>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 4 except that the fine fibrous cellulose C of Preparation Example 3 was used. The obtained sheet was white and opaque, and the thickness was 47 μm.

<Example 12>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 4 except that the fine fibrous cellulose D of Preparation Example 4 was used. The obtained sheet was white and opaque, and the thickness was 45 μm.

<Example 13>
35 g / m as in Example 4 except that diethylene glycol isopropyl methyl ether (DEGIPME) (trade name: Hisolv IPDM, molecular weight 162, boiling point 179 ° C., surface tension 24 N / m) was used as the organic solvent. ² fine fibrous cellulose sheets were obtained. The obtained sheet was white and opaque and had a thickness of 51 μm.

<Example 14>
35 g as in Example 4 except that triethylene glycol monomethyl ether (TEGMME) (trade name: Hymor TM, molecular weight 164, boiling point 249 ° C., surface tension 36 N / m) was used as the organic solvent. / M ² fine fibrous cellulose sheet was obtained. The obtained sheet was white and opaque and had a thickness of 50 μm.

<Example 15>
35 g / m ² as in Example 4 except that diethylene glycol monomethyl ether (DEGMME) (trade name: Hisolv DM, molecular weight 120, boiling point 194 ° C., surface tension 34 N / m) was used as the organic solvent. A fine fibrous cellulose sheet was obtained. The obtained sheet was white and opaque and had a thickness of 52 μm.

<Example 16>
A fine fibrous cellulose sheet of 35 g / m ² was used in the same manner as in Example 4 except that diethylene glycol (DEG) (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 106, boiling point 245 ° C., surface tension 45 N / m) was used as the organic solvent. Obtained. The obtained sheet was white and opaque and had a thickness of 51 μm.

<Example 17>
35 g / m ² fine as in Example 4 except that ethylene glycol mono-t-butyl ether (EGtBE) (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 118, boiling point 152 ° C., surface tension 42 N / m) was used as the organic solvent. A fibrous cellulose sheet was obtained. The obtained sheet was white and opaque and had a thickness of 52 μm.

<Example 18>
1.100 parts by mass of aluminum sulfate (chemical formula: Al ₂ (SO ₄ ) ₃ , solid content: 0.3% by mass) as a cellulose coagulant was added to 100 parts of fine fibrous cellulose C with stirring. The B-type viscosity (25 ° C., 60 rpm, rotor No. 4) of the obtained aqueous suspension (A) was 600 mPa · sec. A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 11 except that the fine fibrous cellulose C added with the cellulose coagulant was used. The obtained sheet was white and opaque, and the thickness was 47 μm. It could be produced at a filtration rate 10 times that of Example 11.

<Example 19>
To 100 parts of fine fibrous cellulose C, 15 parts of a cationic polymer PCA-02 (Toho Chemical Co., Ltd.) aqueous solution diluted with water to 0.1% by mass as a cellulose coagulant was added with stirring. The obtained aqueous suspension had a B-type viscosity (25 ° C., 60 rpm, rotor No. 4) of 1200 mPa · s. A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 11 except that the fine fibrous cellulose C added with the cellulose coagulant was used. The obtained sheet was white and opaque, and the thickness was 45 μm. It could be produced at a filtration rate five times that of Example 11.

<Example 20>
To 100 parts of fine fibrous cellulose C, 10 parts of an aqueous solution (concentration 10% by mass) of ammonium hydrogen carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) as a cellulose coagulant was added with stirring. The B-type viscosity (25 ° C., 60 rpm, rotor No. 4) of the obtained aqueous suspension was 850 mPa · sec. A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 11 except that the fine fibrous cellulose C added with the cellulose coagulant was used. The obtained sheet was white and opaque, and the thickness was 40 μm. It could be produced at a filtration rate 10 times that of Example 11.

<Example 21>
To 100 parts of fine fibrous cellulose C, 5 parts of an aqueous solution obtained by diluting a slightly cationic resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: “SPI203”, solid content 50%, polyamine polyamide resin) to 10% as a cellulose coagulant is stirred. While adding. The obtained aqueous suspension had a B-type viscosity (25 ° C., 60 rpm, rotor No. 4) of 1050 mPa · s. A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 11 except that the fine fibrous cellulose C added with the cellulose coagulant was used. The obtained sheet was white and opaque, and the thickness was 40 μm. It could be produced at a filtration rate 10 times that of Example 11.

<Example 22>
The fine fibrous cellulose sheets obtained in Examples 1 to 21 were impregnated with a thermosetting epoxy resin and cured by treatment at 130 ° C. for 3 minutes. The cellulose sheet before impregnation was a white sheet, but the sheet after impregnation became transparent and the resin and the thermosetting epoxy resin could be combined.

<Example 23>
A wet sheet was prepared while decompressing the fine fibrous cellulose A of Preparation Example 1 on a 500 mesh polyester mesh. The wet sheet had a solid content of 10%. Diethylene glycol dimethyl ether (DEGDME) (manufactured by Toho Chemical Co., Ltd., trade name: “High Solve MDM”, molecular weight 134, boiling point 162 ° C., surface tension 28 N / m) and water were mixed on the obtained wet sheet at a mass ratio of 100: 5. 200 parts of the liquid (100 parts of the organic solvent among them) were uniformly applied by spraying to 100 parts of the wet sheet. A spray spray type was used. The pressure was further reduced to form a wet sheet containing water and an organic solvent. The wet sheet had a solid content of 10%. The ratio of water and organic solvent contained in the wet sheet was 47/53. The wet sheet was dried together with a 500 mesh polyester mesh with a cylinder roll for 3 minutes at 80 ° C. so that the wet sheet was in contact with the mirror surface to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and wet. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The obtained sheet was white and opaque and had a thickness of 55 μm.

<Example 24>
100 parts wet sheet of a solution obtained by mixing 100: 100 mass ratio of diethylene glycol dimethyl ether (DEGDME) (manufactured by Toho Chemical Co., Ltd., trade name: “Hisolv MDM”, molecular weight 134, boiling point 162 ° C., surface tension 28 N / m) and water in a mass ratio of 100: 100 A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 23 except that 200 parts (of which 100 parts of the organic solvent) were uniformly applied by spraying. The obtained sheet was white and opaque, and the thickness was 49 μm.

<Example 25>
100 parts of a wet sheet of a solution obtained by mixing a mass ratio of diethylene glycol dimethyl ether (DEGDME) (manufactured by Toho Chemical Co., Ltd., trade name: “High Solve MDM”, molecular weight 134, boiling point 162 ° C., surface tension 28 N / m) and water at a mass ratio of 100: 400 A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 23 except that 200 parts (of which 40 parts of the organic solvent) were uniformly applied by spraying. The obtained sheet was white and opaque, and the thickness was 37 μm.

<Comparative Example 1>
A wet sheet was prepared while decompressing the fine fibrous cellulose A of Preparation Example 1 on a 500 mesh polyester mesh. The wet sheet was dried at 80 ° C. for 3 minutes together with a 500 mesh polyester mesh to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and was in a dry state. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The sheet remained translucent and the thickness was 35 μm.

<Comparative example 2>
A wet sheet was prepared while decompressing the fine fibrous cellulose B of Preparation Example 2 on a 500 mesh polyester mesh. The wet sheet was dried with a 500 mesh polyester mesh at 80 ° C. for 3 minutes to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and was in a dry state. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The sheet remained translucent and the thickness was 32 μm.

<Comparative Example 3>
A wet sheet was prepared while decompressing the fine fibrous cellulose C of Preparation Example 3 on a 500 mesh polyester mesh. The wet sheet was dried with a 500 mesh polyester mesh at 80 ° C. for 3 minutes to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and was in a dry state. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The sheet remained translucent and the thickness was 29 μm.

<Comparative example 4>
A wet sheet was prepared while decompressing the fine fibrous cellulose D of Preparation Example 4 on a 500 mesh polyester mesh. The wet sheet was dried with a 500 mesh polyester mesh at 80 ° C. for 3 minutes to obtain a sheet after the first drying. The obtained sheet after the first drying was translucent and was in a dry state. The sheet after the first drying was dried at 130 ° C. for 3 minutes (second drying step), and the sheet was peeled off from the polyester mesh to obtain a 35 g / m ² fine fibrous cellulose sheet. The sheet remained translucent and the thickness was 25 μm.

<Comparative Example 5>
A 35 g / m ² fine fibrous cellulose sheet was obtained in the same manner as in Example 1 except that ethanol (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 46, boiling point 78 ° C., surface tension 22 N / m) was used as the organic solvent. The obtained sheet was translucent and had a thickness of 34 μm.

<Comparative Example 6>
35 g / m ² fine fibrous cellulose sheet as in Example 1 except that isopropyl alcohol (IPA) (manufactured by Wako Pure Chemical Industries, molecular weight 60, boiling point 82 ° C., surface tension 21 N / m) was used as the organic solvent. Got. The thickness was 35 μm.

<Comparative Example 7>
35 g / as in Example 1 except that ethylene glycol dimethyl ether (EGDME) (trade name: Hisolv MMM, molecular weight 90, boiling point 84 to 86 ° C., surface tension 23 N / m) was used as the organic solvent. An m ² fine fibrous cellulose sheet was obtained. The thickness was 35 μm.

<Comparative Example 8>
An attempt was made to obtain a fine fibrous cellulose sheet in the same manner as in Example 1 except that ortho-xylene (manufactured by Wako Pure Chemical Industries, boiling point 144 ° C., molecular weight 106) was used as the organic solvent. I couldn't get a sheet.

<Comparative Example 9>
An attempt was made to impregnate the thermosetting resin with the fine fibrous cellulose sheet obtained in Comparative Examples 1 to 7, but the thermosetting resin was not impregnated into the fine fibrous cellulose sheet, and a composite sheet was not obtained.

[Evaluation method]
1. Air Permeability The air permeability of the fine fibrous cellulose sheet was measured using the JAPAN TAPPI Paper Pulp Test Method No. It was measured according to 5-2: 2000 (Oken type). The lower the air permeability, the better the resin impregnation.

2. Pore volume and pore surface area The pore volume and pore surface area of a fine fibrous cellulose sheet having a diameter of 1 μm or less were measured with a mercury porosimeter (manufactured by Shimadzu Corporation, trade name: “Autopore IV9505”). The larger the pore volume and pore surface area, the better the impregnation of the resin. The pore volume is preferably 0.1 or more and 2 mL / g or less. When the pore volume is less than 0.1 mL / g, impregnation is impossible. When the pore volume exceeds 2 ml / g, the ratio of the fine fibrous cellulose to the impregnated resin becomes small, which is not preferable. The pore surface area is preferably 40 m ² / g or more and 200 m ² / g or less. If it is less than 40 m ² / g, the impregnation property of the resin deteriorates, and if it exceeds 200 m ² / g, the strength of the sheet is undesirably lowered.

  As is apparent from Table 1, the sheet obtained by the method for producing a fine fibrous cellulose sheet of the present invention has a low air permeability, is a porous sheet, and is a resin composite that is excellent in transparency when impregnated with a resin. The body is obtained. Further, as is apparent from Table 2, it can be seen that the porosity (air permeability, pore volume, pore surface area) can be controlled by changing the blending ratio of the organic solvent and water.

  According to the production method of the present invention, a porous sheet of fine fibrous cellulose can be produced simply and efficiently. Moreover, the composite base material useful for a flexible transparent substrate etc. can be obtained by impregnating resin to the obtained fine fibrous cellulose sheet.

Claims (13)

  In the method for producing a fine fibrous cellulose sheet, a dispersion step of dispersing the fine fibrous cellulose in water, the dispersion obtained in the dispersion step is dehydrated by filtration on a porous substrate, and a sheet containing moisture is obtained. A paper making process to form, an organic solvent treatment step for applying an organic solvent to the moisture-containing sheet to form a sheet containing moisture and an organic solvent, and a drying step for drying the sheet containing moisture and the organic solvent. A method for producing a fine fibrous cellulose sheet, wherein the organic solvent used in the organic solvent treatment step has a boiling point of 120 to 260 ° C. and is water-soluble.   In the said dispersion | distribution process, a cellulose coagulant is mix | blended with a dispersion liquid, The manufacturing method of the fine fibrous cellulose sheet | seat of Claim 1 characterized by the above-mentioned.   The method for producing a fine fibrous cellulose sheet according to claim 2, wherein the cellulose coagulant is at least one selected from inorganic salts or an organic compound containing a cationic functional group.   The method for producing a fine fibrous cellulose sheet according to claim 2 or 3, wherein the cellulose coagulant is at least one selected from ammonium hydrogen carbonate, ammonium carbonate, aluminum sulfate, and polyamide-based fine cationic resin.   The method for applying the organic solvent is at least one method selected from a spray coater, a curtain coater, a gravure coater, a bar coater, a blade coater, and a size press coater. The manufacturing method of the fine fibrous cellulose sheet of description.   The organic solvent applied to the water-containing sheet is diluted with water, and the mass ratio of the organic solvent to water is 100: 1 to 100: 1000. The manufacturing method of the fine fibrous cellulose sheet of description.   The said drying process is equipped with the two-stage drying process of evaporating water in a 1st drying process, and then evaporating an organic solvent in a 2nd drying process, The any one of Claims 1-6 characterized by the above-mentioned. Method for producing a fine fibrous cellulose sheet.   The mass ratio of water and the organic solvent contained in the sheet containing the water and the organic solvent is 100: 10 to 10: 100, and the fine fibrous form according to any one of claims 1 to 7 A method for producing a cellulose sheet.   The method for producing a fine fibrous cellulose sheet according to any one of claims 1 to 8, wherein the organic solvent is a glyme.   The method for producing fine fibrous cellulose according to any one of claims 1 to 9, wherein the organic solvent is diethylene glycol dimethyl ether.   The fiber width of the said fine fibrous cellulose is 2-1000 nm, The manufacturing method of the fine fibrous cellulose sheet of any one of Claims 1-10 characterized by the above-mentioned.   The method for producing a fine fibrous cellulose sheet according to any one of claims 1 to 11, wherein the concentration of the fine fibrous cellulose in the dispersion is 0.1 to 1% by mass.   A composite of fine fibrous cellulose obtained by impregnating a fine fibrous cellulose sheet obtained by the production method according to any one of claims 1 to 12 with a resin.