WO2013022025A1

WO2013022025A1 - Process for producing microfibrous cellulose, process for producing nonwoven fabric, microfibrous cellulose, slurry containing microfibrous cellulose, nonwoven fabric, and composite

Info

Publication number: WO2013022025A1
Application number: PCT/JP2012/070208
Authority: WO
Inventors: 泰友野一色; 裕一野口; 岸田　隆之; 日出子赤井
Original assignee: 王子ホールディングス株式会社
Priority date: 2011-08-08
Filing date: 2012-08-08
Publication date: 2013-02-14
Also published as: JP2013136859A; JP5828288B2

Abstract

The present invention relates to a process for producing microfibrous cellulose which comprises: a carboxy group introduction step in which a fibrous raw material comprising cellulose is treated with at least one carboxylic acid-based compound selected from the group consisting of compounds having two or more carboxy groups, acid anhydrides of compounds having two or more carboxy groups, and derivatives of these to introduce carboxy groups into the cellulose; an alkali treatment step in which after completion of the carboxy group introduction step, the cellulose into which carboxy groups have been introduced is treated with an alkali solution; and a fibrillation step in which the cellulose which has undergone the alkali treatment is fibrillated. According to the invention, it is possible to provide a process for microfibrous-cellulose production in which microfibrous cellulose is highly efficiently produced from a fibrous raw material and which is low in cost and reduced in environmental burden.

Description

Method for producing fine fibrous cellulose, method for producing nonwoven fabric, fine fibrous cellulose, slurry containing fine fibrous cellulose, nonwoven fabric, and composite

The present invention relates to a method for producing fine fibrous cellulose, a method for producing a non-woven fabric, fine fibrous cellulose, a fine fibrous cellulose-containing slurry, a non-woven fabric, and a composite.
This application is filed in Japanese Patent Application No. 2011-173194 filed in Japan on August 8, 2011, Japanese Patent Application No. 2011-258664 filed in Japan on November 28, 2011, and Japan on February 7, 2012. Claiming priority based on Japanese Patent Application No. 2012-024457 filed in Japan, the contents of which are incorporated herein by reference.

In recent years, materials that use reproducible natural fibers have attracted attention due to the substitution of petroleum resources and the growing environmental awareness. Among natural fibers, cellulose fibers having a fiber diameter of 10 to 50 μm, especially wood-derived cellulose fibers (pulp) have been widely used as paper products so far.
In addition, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known as the cellulose fiber, and the sheet containing the fine fibrous cellulose has advantages such as high mechanical strength, and can be used for various applications. Application has been studied (Patent Document 1). For example, it is known that fine fibrous cellulose is made into a non-woven fabric and used as a high-strength sheet.

As a method for producing fine fibrous cellulose, Patent Document 2 discloses a method of treating lignocellulose in an aqueous solvent containing a nitroxyl radical derivative, an alkali bromide and an oxidizing agent.
Patent Document 3 discloses a method in which a polybasic acid anhydride is half-esterified into a part of a hydroxy group of cellulose to introduce a carboxy group, and then fibrillated and refined.

JP 2008-24788 A JP 2008-308802 A JP 2009-293167 A

However, Patent Document 2 requires the use of a special catalyst, which increases the cost. In the method for producing fine fibrous cellulose described in Patent Document 3, the fiber raw material is insufficiently refined. Since the yield was low and the dispersion was insufficiently stable, there were problems such as low production efficiency from the fiber raw material, high cost, and high environmental load.
An object of this invention is to provide the manufacturing method of the fine fibrous cellulose which solved the said problem, the manufacturing method of a nonwoven fabric, a fine fibrous cellulose, a fine fibrous cellulose containing slurry, a nonwoven fabric, and a composite_body | complex.

The present invention relates to the following.
(1) A compound containing two or more carboxy groups, an acid anhydride of a compound having two or more carboxy groups, and at least one carboxylic acid compound selected from the group consisting of derivatives thereof include cellulose. After the fiber raw material is treated, a carboxy group introduction step for introducing a carboxy group into the cellulose, an alkali treatment step for treating the cellulose introduced with the carboxy group with an alkaline solution after the completion of the carboxy group introduction step, and after the alkali treatment A method for producing fine fibrous cellulose, comprising a defibrating treatment step of defibrating cellulose of
(2) The method for producing fine fibrous cellulose according to (1), wherein the carboxy group introduction step is a step of adding the carboxylic acid compound to a hydroxy group of cellulose.
(3) The carboxylic acid compound is a compound selected from the group consisting of maleic acid, succinic acid, phthalic acid, maleic acid, succinic acid, acid anhydrides of phthalic acid, and derivatives thereof (1) or (2) The manufacturing method of the fine fibrous cellulose as described in
(4) The method for producing fine fibrous cellulose according to any one of (1) to (3), wherein the carboxylic acid compound is an acid anhydride,
(5) The method for producing fine fibrous cellulose according to any one of (1) to (4), wherein the carboxy group introduction step is a step of treating cellulose with the gasified carboxylic acid compound,
(6) The method for producing fine fibrous cellulose according to any one of (1) to (5), further comprising preliminarily setting the moisture of the fiber raw material to 10% by mass or less based on the dry weight of the fiber raw material. ,
(7) a dehydration step of dehydrating a slurry containing fine fibrous cellulose produced by the method for producing fine fibrous cellulose according to any one of (1) to (6) on a filter medium to obtain a wet paper; A method for producing a nonwoven fabric comprising a drying step of drying the wet paper,
(8) A fine fibrous cellulose having a fiber width of 1 to 1000 nm, wherein a part of the hydroxy groups of cellulose constituting the fibers is a hydroxy group substituted with a functional group represented by the following structural formula (1) ,

(In the structural formula (1), R represents a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched group. Any of a chain hydrocarbon group, an aromatic group, and a single bond, and M is a cationic group.)
(9) A fine fibrous cellulose-containing slurry in which the fine fibrous cellulose according to (8) is dispersed in a dispersion medium,
(10) A nonwoven fabric containing the fine fibrous cellulose according to (8),
(11) A composite containing the fine fibrous cellulose described in (8) and a matrix material, and (12) a composite containing the nonwoven fabric described in (10) and a matrix material.

According to the method for producing fine fibrous cellulose of the present invention, since the fiber raw material can be sufficiently refined and the yield of fine fibrous cellulose is high, the production efficiency of fine fibrous cellulose from the fiber raw material is high. Moreover, the manufacturing method of the fine fibrous cellulose of this invention is low cost, and its environmental impact is small.
According to the method for producing a nonwoven fabric of the present invention, the production efficiency of the nonwoven fabric with respect to the fiber raw material can be improved.
Since the fine fibrous cellulose of the present invention has a small fiber width and a large axial ratio (fiber length / fiber width), the slurry stability of the fine fibrous cellulose is high, and the resulting nonwoven fabric has a high strength. The composite of the fine fibrous cellulose and the matrix resin of the present invention has high strength and a low linear thermal expansion coefficient.

2 is a transmission electron micrograph of cellulose contained in the defibrated pulp slurry obtained in Example 1. FIG. 3 is a transmission electron micrograph of cellulose contained in the defibrated pulp slurry obtained in Example 2. FIG. 4 is a transmission electron micrograph of cellulose contained in the defibrated pulp slurry obtained in Example 3. FIG. 4 is a transmission electron micrograph of cellulose contained in the defibrated pulp slurry obtained in Example 4. It is a schematic block diagram of one Embodiment of the manufacturing apparatus used with the manufacturing method of the nonwoven fabric of this invention.

<Fine fibrous cellulose>
In the fine fibrous cellulose of the present invention, a part of the hydroxy group (—OH group) is substituted with a functional group represented by the following structural formula (1). The fine fibrous cellulose of the present invention is a cellulose fiber or cellulose rod-like particles that are much thinner than pulp fibers that are usually used in papermaking applications.

R in the structural formula (1) is a group connecting two carboxy groups of a carboxylic acid compound used in a carboxy group introduction step described later, and is a group derived from each carboxylic acid compound. Specifically, a saturated-linear hydrocarbon group (for example, derived from malonic acid or succinic acid), a saturated-branched hydrocarbon group (for example, 2-methylpropanediacid, 2-methylbutanedioic acid, etc.) ), Saturated-cyclic hydrocarbon group (for example, derived from 1,2-cyclohexanedicarboxylic acid, etc.), unsaturated-linear hydrocarbon group (for example, derived from maleic acid or fumaric acid, etc.), unsaturated-branched Chain hydrocarbon groups (eg, derived from 2-methyl-2-butenedioic acid, itaconic acid, etc.), aromatic groups (eg, derived from phthalic acid, isophthalic acid, etc.), and carboxy groups and hydroxyl groups for them Examples thereof include a derivative group to which a functional group such as a group is added (for example, derived from citric acid or pyromellitic acid), or a single bond (for example, derived from oxalic acid).
In addition, R in the structural formula (1) may have two or more carboxy groups or hydroxy groups with respect to the main structure composed of a hydrocarbon group.

M in the structural formula (1) is a cationic group, and forms a carboxylate by pairing with the carboxy group in the structural formula (1).
As the cationic group M forming the carboxylate, monovalent and polyvalent cationic groups can be selected and used as desired. Specific examples include a cation of an alkali metal such as sodium, potassium or lithium, a cation of a divalent metal such as calcium or magnesium, and ammonium, aliphatic ammonium, or aromatic ammonium. A combination of two or more kinds of cationic groups can also be applied. Among the cationic groups M, sodium ions, potassium ions, and ammonium are preferable because they are versatile.

When the minor axis of the fine fibrous cellulose of the present invention is defined as the width, the cellulose fiber width is preferably 1 nm to 1000 nm, more preferably 2 nm to 500 nm, and still more preferably 4 nm to 100 nm, as observed with an electron microscope. When the fiber width of the fine fibrous cellulose is less than 1 nm, the physical properties (strength, rigidity, or dimensional stability) as the fine fibrous cellulose are not expressed because cellulose molecules are dissolved in water. On the other hand, if it exceeds 1000 nm, it cannot be said to be fine fibrous cellulose, but is merely a fiber contained in ordinary pulp, and physical properties (strength, rigidity, or dimensional stability) as fine fibrous cellulose cannot be obtained.
In applications where transparency is required for fine fibrous cellulose, when the fiber width exceeds 30 nm, it approaches 1/10 of the wavelength of visible light, and when combined with a matrix material, visible light is refracted and scattered at the interface. The fiber width is preferably 2 nm to 30 nm, more preferably 2 to 20 nm, because it tends to occur and the transparency tends to decrease. A composite obtained from fine fibrous cellulose as described above generally has a high strength because it becomes a dense structure, and in addition to obtaining a high elastic modulus derived from cellulose crystals, it also scatters visible light. Since there are few, high transparency is also obtained.

The fine fibrous cellulose of the present invention is an aggregate of cellulose molecules and has a crystal structure. Its crystal structure is type I (parallel chain).
Here, the fine fibrous cellulose has the I-type crystal structure in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromated with graphite. It can be identified by having typical peaks at two positions near 14 to 17 ° and 2θ = 22 to 23 °.
Moreover, the measurement of the fiber width by electron microscope observation of fine fibrous cellulose is performed as follows. A fine fibrous cellulose-containing slurry is prepared, and the slurry is cast on a carbon film-coated grid subjected to a hydrophilization treatment to obtain a sample for TEM observation. When wide fibers are included, an SEM image of the surface cast on glass may be observed. Observation by an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, 20000 times, 40000 times, or 50000 times depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions (1) and (2).
(1) One straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicularly intersecting the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The width of the fiber intersecting with the straight line X or the straight line Y is visually read with respect to the observation image satisfying the above conditions. In this way, at least three sets of images of the surface portion not overlapping each other are observed, and the width of the fiber intersecting with the straight line X or the straight line Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read. The fine fiber width in the present invention is an average value of the fiber widths read in this way.

When the major axis of the fine fibrous cellulose of the present invention is taken as the length, the fiber length is preferably 0.1 μm or more. When the fiber length is less than 0.1 μm, it is difficult to obtain the strength improvement effect when the fine fibrous cellulose is combined with the resin. The fiber length can be determined by TEM, SEM, or AFM image analysis. The said fiber length is a fiber length of the cellulose which occupies 30 mass% or more of fine fibrous cellulose.
The fiber length of the fine fibrous cellulose of the present invention is preferably from 0.1 to 100 μm, more preferably from 0.1 to 50 μm, still more preferably from 0.1 to 10 μm.

The axial ratio (fiber length / fiber width) of the fine fibrous cellulose according to the present invention is preferably in the range of 100 to 10,000. If the axial ratio is less than 100, it may be difficult to form a fine fibrous cellulose-containing nonwoven fabric. When the axial ratio exceeds 10,000, the slurry viscosity becomes high, which is not preferable.

As for the ratio of the crystal part contained in the fine fibrous cellulose of the present invention, the crystallinity obtained by the X-ray diffraction method is 60% or more, but the crystallinity is preferably 65% or more, more preferably 70%. When it is above, further superior performance can be expected in terms of heat resistance and low linear thermal expansion. The degree of crystallinity can be obtained by measuring an X-ray diffraction profile and determining the crystallinity by a conventional method (Segal et al., Textile Research Journal, 29, 786, 1959).
The range of the crystallinity is preferably 60 to 100%, more preferably 65 to 95%, and further preferably 70 to 90%.

<Manufacture of fine fibrous cellulose>
In the method for producing fine fibrous cellulose of the present invention, a fiber raw material containing cellulose is treated with a carboxylic acid compound to introduce a carboxy group into cellulose, and after completion of the carboxy group introduction step, a carboxy group is introduced. Cellulose (hereinafter referred to as “carboxy group-introduced cellulose”) introduced with an alkali solution, and the cellulose after the alkali treatment (hereinafter referred to as “alkali-treated cellulose”) is defibrated. And a defibrating process.

(Carboxy group introduction step)
Examples of the method for treating the fiber raw material with the carboxylic acid compound include a method of mixing the gasified carboxylic acid compound with the fiber raw material, or a method of adding the carboxylic acid compound to the fiber raw material slurry. Among these, since the process is simple and the efficiency of introducing a carboxy group is high, a method of mixing a gasified carboxylic acid compound with a fiber raw material is preferable. Examples of the method for gasifying the carboxylic acid compound include a method for heating the carboxylic acid compound.
In the carboxy group introduction step, it is preferable to add a carboxylic acid compound to cellulose because the yield of fine fibrous cellulose is further improved. In addition of a carboxylic acid compound to cellulose, a carboxylic acid compound is added to the hydroxy group of cellulose.

Examples of the fiber raw material containing cellulose include paper pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as hemp, straw or bagasse; or cellulose isolated from squirts or seaweed . Among these, paper pulp is preferable in terms of availability. Paper pulp includes hardwood kraft pulp (bleached kraft pulp (LBKP), unbleached kraft pulp (LUKP), oxygen bleached kraft pulp (LOKP), etc.), softwood kraft pulp (bleached kraft pulp (NBKP), unbleached kraft pulp) (NUKKP, oxygen bleached kraft pulp (NOKP), etc.), sulfite pulp (SP), soda pulp (AP) and other chemical pulp; semi-chemical pulp (SCP), semi-chemical pulp (CGP), etc. Chemical pulp; mechanical pulp such as groundwood pulp (GP), thermomechanical pulp (TMP, or BCTMP); non-wood pulp made from straw, sanjo, hemp, kenaf, etc .; or deinked pulp made from waste paper Can be mentioned. Among these, kraft pulp, deinked pulp, or sulfite pulp is preferable because it is more easily available.
A fiber raw material may be used individually by 1 type, and may be used in mixture of 2 or more types.

The fiber raw material is preferably dried in advance before the carboxy group introduction step to reduce the water content. Specifically, the water content of the fiber raw material is 10% by mass or less based on the absolute dry weight of the fiber raw material. It is preferably 7% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less.
The moisture content of the fiber raw material is preferably 0 to 10% by mass, more preferably 1 to 7% by mass, further preferably 1 to 5% by mass, and particularly preferably 1 to 3% by mass.
If the moisture of the fiber raw material is reduced, fine fibrous cellulose having a large axial ratio can be easily obtained. When fine fibrous cellulose having a large axial ratio is blended with a nonwoven fabric, a fiber reinforced resin, or a paper base material, the strength can be easily improved.
Moreover, it is also included in the scope of the present invention to use a fiber material having a moisture content of 10% by mass or less based on the absolute dry weight of the fiber material.

The carboxylic acid compound used in the present invention is at least one compound selected from the group consisting of a compound having two or more carboxy groups, an acid anhydride of a compound having two or more carboxy groups, and derivatives thereof. It is. Among the compounds having two or more carboxy groups, compounds having two or more carboxy groups are preferable, and compounds having two carboxy groups (dicarboxylic acid compounds) are more preferable.
Examples of the compound having two or more carboxy groups include propanedioic acid (malonic acid), butanedioic acid (succinic acid), pentanedioic acid (glutaric acid), hexanedioic acid (adipic acid), 2-methylpropanedioic acid 2-methylbutanedioic acid, 2-methylpentanedioic acid, 1,2-cyclohexanedicarboxylic acid, 2-butenedioic acid (maleic acid or fumaric acid), 2-pentenedioic acid, 2,4-hexadienedioic acid, 2 -Methyl-2-butenedioic acid, 2-methyl-2-pentenedioic acid, 2-methylidenebutanedioic acid (itaconic acid), benzene-1,2-dicarboxylic acid (phthalic acid), benzene-1,3-dicarboxylic acid ( Examples thereof include dicarboxylic acid compounds such as isophthalic acid), benzene-1,4-dicarboxylic acid (terephthalic acid), and ethanedioic acid (oxalic acid).
Examples of the derivative of a compound having two or more carboxy groups include 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), or benzene-1,2,4,5-tetracarboxylic acid (pyrrole). Derivatives of the dicarboxylic acid compound such as merit acid).
Examples of the acid anhydride of the compound having two or more carboxy groups include maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride, pyromellitic anhydride, or 1,2, -Acid anhydrides of dicarboxylic acid compounds such as cyclohexanedicarboxylic acid and compounds containing two or more carboxy groups.
The acid anhydride derivative of a compound having two or more carboxy groups includes at least an acid anhydride of a compound having a carboxy group, such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, or diphenylmaleic acid anhydride. One in which a part of hydrogen atoms is substituted with a substituent (for example, an alkyl group or a phenyl group) can be mentioned.
Among these, maleic anhydride, succinic anhydride, or phthalic anhydride is preferable because it is industrially applicable and easily gasified.

The mass ratio of the carboxylic acid compound to the fiber raw material is preferably 0.1 to 500 parts by mass, more preferably 10 to 200 parts by mass with respect to 100 parts by mass of the fiber raw material. . If the ratio of a carboxylic acid type compound is more than the said lower limit, the yield of a fine fibrous cellulose can be improved more. However, even if the upper limit is exceeded, the effect of improving the yield reaches its peak, and the carboxylic acid compound is merely used in vain.

In the present invention, by introducing a carboxy group, a part of the hydroxy group (—OH group) of cellulose of the fiber raw material forms an ester bond. The amount of carboxy groups introduced into the hydroxy group (—OH group) of cellulose as a fiber raw material is preferably in the range of 0.1 to 2.0 mmol / g as the amount introduced per gram of cellulose. Within the above range, the dispersion stability of the fine fibrous cellulose-containing slurry obtained by refinement is excellent. If the introduction amount of the carboxy group is less than 0.1 mmol / g, the dispersion stability of the fine fibrous cellulose-containing slurry may be inferior and may easily aggregate. Fibrous cellulose may be dissolved.
The amount of carboxy group introduced can be determined by measuring the amount of carboxy group according to TAPPI T237 cm-08 (2008) Carboxyl content of pulp. However, in the present invention, in order to make it possible to obtain the introduction amount of the carboxy group over a wider range, among the test solutions used in the measurement method, sodium bicarbonate (NaHCO ₃ ) / sodium chloride (NaCl) = 0. About a test solution obtained by dissolving 0.84 g / 5.85 g in 1000 ml with distilled water, the concentration of the test solution was changed to sodium bicarbonate / sodium chloride = 3.36 g / 23.40 g so that the concentration of the test solution was almost 4 times. . Moreover, the difference in the amount of carboxy groups before and after introduction of the carboxy group was defined as the substantial introduction amount of the carboxy group.

The apparatus used for introducing the carboxy group is not particularly limited. For example, a heating reaction vessel having a stirring blade, a rotary heating reaction vessel, a pressure vessel having a heating jacket, a rotary pressure vessel, a uniaxial mixer having a heating jacket, and a biaxial A mixer or a kneading apparatus having a heating device such as a twin-screw extruder, a multi-screw kneading extruder, a pressure kneader, or a double-arm kneader may be used.

The treatment temperature of cellulose in the carboxy group introduction step is preferably 0 ° C. or higher and 250 ° C. or lower from the viewpoint of the thermal decomposition temperature of cellulose.
Further, when water is contained in the treatment, the temperature is preferably 80 to 200 ° C, more preferably 100 to 170 ° C.

In the carboxy group introduction step, a catalyst can be used if desired. As the catalyst, it is preferable to use a basic catalyst such as pyridine, triethylamine, sodium hydroxide, or sodium acetate, or an acidic catalyst such as acetic acid, sulfuric acid, or perchloric acid.

After the fiber raw material has been treated with the carboxylic acid compound, it is preferable to carry out an alkali treatment step described later. It can be washed with water or an organic solvent (for example, acetone).
However, when water is used, the fiber length may be shortened because an acid generated by dissolution or hydrolysis of the carboxylic acid compound hydrolyzes cellulose.

(Alkali treatment process)
Although it does not specifically limit as a method of an alkali treatment, For example, the method of immersing carboxy group introduction | transduction cellulose in an alkaline solution is mentioned.
The alkali compound contained in the alkali solution may be an inorganic alkali compound or an organic alkali compound. Examples of inorganic alkali compounds include alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal carbonates or alkaline earth metal carbonates, alkali metal phosphates or alkaline earth metal phosphorus. Acid salts. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide, and examples of the alkaline earth metal hydroxide include calcium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, and sodium hydrogen carbonate. Examples of the alkaline earth metal carbonate include calcium carbonate.
Examples of the alkali metal phosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of alkaline earth metal phosphates include calcium phosphate and calcium hydrogen phosphate.
Examples of the organic alkali compounds include ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates, and phosphates.
More specifically, the organic alkali compound contained in the alkali solution of the present invention includes, for example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane. , Diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4 -Aminopyridine, ammonium carbonate, ammonium hydrogen carbonate, diammonium hydrogen phosphate and the like.

The solvent in the alkaline solution may be either water or an organic solvent, but a polar solvent (polar organic solvent such as water or alcohol) is preferred, and an aqueous solvent containing at least water is more preferred.
Among alkaline solutions, a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution and an ammonia aqueous solution are particularly preferred because of their high versatility.

The pH at 25 ° C. of the alkaline solution in which the carboxy group-introduced cellulose is immersed is preferably 9 or more and 14 or less, more preferably 10 or more and 14 or less, and even more preferably 11 or more and 14 or less. If the pH of the alkaline solution is at least the lower limit, the yield of fine fibrous cellulose will be higher. However, when pH exceeds 14, the handleability of an alkaline solution will fall.
In the present invention, “the pH at 25 ° C. of the alkaline solution in which the carboxy group-introduced cellulose is immersed is 9 or more” means that the pH of the alkaline solution in which the carboxy group-introduced cellulose is immersed is based on a temperature of 25 ° C. It means within the above range. That is, when the alkaline solution is prepared at a temperature other than 25 ° C., the pH range is corrected according to the temperature. It is also included in the scope of the present invention to prepare the alkaline solution in the pH range thus corrected.

The temperature of the alkali solution in the alkali treatment step is preferably 0 to 50 ° C, more preferably 10 to 40 ° C.

By the alkali treatment, the carboxylic acid introduced into the cellulose becomes a carboxylate and forms a chemical structure of the structural formula (1).
The amount of carboxylate introduced by the alkali treatment step is preferably 0.1 to 2.0 mmol / g. Within the above range, many of the introduced carboxy groups are in the form of salts.
By introducing a carboxylate into cellulose, miniaturization is facilitated, and the fibrillation efficiency is significantly improved. Further, the dispersion stability as a slurry of fine fibrous cellulose is particularly good. The reason is not clear, but it is presumed that the electrical repulsion between cellulose fibers is strong.

After the alkali treatment, it is preferable to wash the alkali-treated cellulose with water or an organic solvent before the defibrating treatment step in order to improve the handleability.

(Defibration process)
In the defibrating process, usually, the alkali-treated cellulose is defibrated using a defibrating apparatus to obtain a fine fibrous cellulose-containing slurry.
Defibration treatment equipment includes high-speed defibrator, grinder (stone mortar grinder), high-pressure homogenizer and ultra-high pressure homogenizer, high-pressure collision grinder, ball mill, bead mill, disk refiner, conical refiner, twin-screw kneader, vibration mill An apparatus for wet pulverization, such as a homomixer under high-speed rotation, an ultrasonic disperser, or a beater, can be used as appropriate.

A preferable defibrating method includes a method of defibrating an alkali-treated cellulose slurry into which a carboxy group has been introduced using one or more of the above defibrating devices. In the defibrating process, two or more kinds of defibrating apparatuses can be used in combination.

In the defibrating process, it is preferable to dilute the alkali-treated cellulose with water and an organic solvent alone or in combination to form a slurry. The solid content concentration of the alkali-treated cellulose after dilution is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass. If the solid content concentration of the alkali-treated cellulose after dilution is equal to or higher than the lower limit, the efficiency of the defibrating process is improved, and if it is equal to or lower than the upper limit, blockage in the defibrating apparatus can be prevented.

(Chemical modification treatment)
In the present invention, chemical modification treatment may be applied to cellulose. Here, chemical modification is to add a compound by reacting a hydroxy group in cellulose with a chemical modifier. The chemical modification treatment may be performed at any point in the production of the fine fibrous cellulose, may be performed on the fiber raw material, may be performed on the carboxy group-introduced cellulose, or may be performed on the alkali-treated cellulose, You may give to the below-mentioned nonwoven fabric. Moreover, you may perform a chemical modification process simultaneously with a carboxy group introduction | transduction process.

As functional groups to be introduced into cellulose by chemical modification, acetyl group, acryloyl group, methacryloyl group, propionyl group, propioyl group, butyryl group, 2-butyryl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, nonanoyl group, Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, benzoyl group, naphthoyl group, nicotinoyl group, isonicotinoyl group, furoyl group, cinnamoyl group and other acyl groups, 2-methacryloyloxyethyl isocyanate Isocyanate group such as noyl group, methyl group, ethyl group, propyl group, 2-propyl group, butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl Group, nonyl group, decyl group, undecyl group, dodecyl group, myristyl group, palmityl group or stearyl alkyl group such as an oxirane group, an oxetane group, a thiirane group, or a thietane group, and the like. Among these, an acyl group having 2 to 12 carbon atoms such as an acetyl group, an acryloyl group, a methacryloyl group, a benzoyl group, or a naphthoyl group, or an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, or a propyl group. Groups are preferred.

The modification method is not particularly limited, and there is a method of reacting cellulose fibers with the following chemical modifiers. Although there are no particular limitations on the reaction conditions, a solvent, a catalyst, or the like can be used, or heating, decompression, or the like can be performed as desired.

Examples of the chemical modifier include one or more substances selected from the group consisting of cyclic ethers such as acids, acid anhydrides, alcohols, halogenating reagents, isocyanates, alkoxysilanes, and oxiranes (epoxies). Can be mentioned.

Examples of the acid include acetic acid, acrylic acid, methacrylic acid, propanoic acid, butanoic acid, 2-butanoic acid, and pentanoic acid.
Examples of the acid anhydride include acetic anhydride, acrylic anhydride, methacrylic anhydride, propanoic anhydride, butanoic anhydride, 2-butanoic anhydride, and pentanoic anhydride.
Examples of the halogenating reagent include acetyl halide, acryloyl halide, methacryloyl halide, propanoyl halide, butanoyl halide, 2-butanoyl halide, pentanoyl halide, benzoyl halide, or naphthoyl halide.
Examples of the alcohol include methanol, ethanol, propanol, and 2-propanol.
Examples of the isocyanate include methyl isocyanate, ethyl isocyanate, and propyl isocyanate.
Examples of the alkoxysilane include methoxysilane and ethoxysilane.
Examples of the cyclic ether such as oxirane (epoxy) include ethyl oxirane or ethyl oxetane.
Among these, acetic anhydride, acrylic anhydride, methacrylic anhydride, benzoyl halide, or naphthoyl halide is particularly preferable.
These chemical modifiers may be used alone or in combination of two or more.

As the catalyst, it is preferable to use a basic catalyst such as pyridine, triethylamine, sodium hydroxide, or sodium acetate, or an acidic catalyst such as acetic acid, sulfuric acid, or perchloric acid.

As the temperature condition for the chemical modification, if it is too high, there is concern about yellowing of cellulose or a decrease in the degree of polymerization, and if it is too low, the reaction rate decreases, so 10 to 250 ° C. is preferable. Although the reaction time depends on the chemical modifier and the chemical modification rate, it is usually from several minutes to several tens of hours.

In the present invention, the chemical modification rate of cellulose is usually 65 mol% or less, preferably 50 mol% or less, more preferably 40 mol% or less, based on the total hydroxy groups of cellulose. There is no particular lower limit for the chemical modification rate.
By performing chemical modification, the decomposition temperature of cellulose increases and the heat resistance increases, but if the chemical modification rate is too high, the cellulose structure is destroyed and the crystallinity is lowered. The thermal expansion coefficient tends to increase, which is not preferable.

The chemical modification rate as used herein refers to the proportion of all hydroxy groups in cellulose that have been chemically modified. The chemical modification rate can be determined by IR, NMR, titration method or the like. For example, the chemical modification rate of the ester can be measured by the following titration method.

Weigh accurately 0.05 g of dry cellulose, and add 1.5 ml of ethanol and 0.5 ml of distilled water to this. This is allowed to stand in a hot water bath at 60 to 70 ° C. for 30 minutes, and then 2 ml of 0.5N aqueous sodium hydroxide solution is added. This is left to stand in a hot water bath at 60 to 70 ° C. for 3 hours, and then shaken with an ultrasonic cleaner for 30 minutes. This is titrated with 0.2N hydrochloric acid standard solution using phenolphthalein as an indicator.
Here, from the amount Z (ml) of the 0.2N aqueous hydrochloric acid solution required for the titration, the number of moles Q of the substituent introduced by chemical modification is obtained by the following formula.
Q (mol) = 0.5 (N) × 2 (ml) /1000−0.2 (N) × Z (ml) / 1000
Here, the introduction amount of the carboxy group before chemical modification is A mmol / g, a mol%, the molecular weight of the substituent is S, and the introduction amount of the chemical modification group is B mmol / g, b mol%, the substituent. Assuming that the molecular weight of T is A, Ammol / g is calculated by the above method, and a mol% is calculated from Ammol / g by the following formula (I).

On the other hand, Bmmo / g is calculated from Q and A by the following formula (II).
B (mmol / g) = (Q × 1000) / sample amount−2A (II)
Further, Bmmol / g and b mol% are in the relationship of the following formula (III).

Therefore, b mol% is represented by the following formula (IV).

(Function and effect)
According to the manufacturing method of the said fine fibrous cellulose, a fiber raw material can fully be refined | miniaturized, the yield of a fine fibrous cellulose becomes high, and the manufacturing efficiency of a fine fibrous cellulose improves. The reason for this is that by subjecting the carboxy group-introduced cellulose to an alkali treatment, the electrostatic repulsion between the cellulose fibers is increased, the osmotic pressure of water between the cellulose is improved, and the defibration property is increased. Guessed.
Moreover, since the manufacturing method of the said fine fibrous cellulose does not use a nitroxy radical derivative, an alkali bromide, and an oxidizing agent, cost is low and environmental impact is also small.

<Slurry containing fine fibrous cellulose>
The fine fibrous cellulose-containing slurry of the present invention is obtained by dispersing fine fibrous cellulose in a dispersion medium.
As the dispersion medium, a polar organic solvent can be used in addition to water. Preferred polar organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, or t-butyl alcohol. , Ketones such as acetone or methyl ethyl ketone (MEK), ethers such as diethyl ether or tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or dimethylacetamide (DMAc). These may be one type or two or more types. Moreover, if it is a range which does not prevent the dispersion stability of a fine fibrous cellulose containing slurry, in addition to said water and a polar organic solvent, a nonpolar organic solvent can be used.
The content of fine fibrous cellulose in the fine fibrous cellulose-containing slurry is preferably 0.05 to 20% by mass, and more preferably 0.1 to 10% by mass. If the content of the fine fibrous cellulose is not less than the lower limit, the production efficiency when producing the nonwoven fabric and the composite described later is excellent, and if it is not more than the upper limit, the dispersion stability of the slurry is excellent.

Examples of the method for producing the fine fibrous cellulose-containing slurry include stirring and dispersing the slurry using a dispersing device such as a homomixer, a pulper, or a disaggregator.

<Nonwoven fabric>
Below, one embodiment of the nonwoven fabric of the present invention and its manufacturing method is described.
The nonwoven fabric of the present invention contains the fine fibrous cellulose.

The thickness of the nonwoven fabric of the present invention is not particularly limited, but is preferably 10 μm or more, more preferably 50 μm or more, particularly preferably 80 μm or more, preferably 10 cm or less, more preferably 1 cm or less, more preferably 1 mm. Hereinafter, it is particularly preferably 250 μm or less. The thickness range of the nonwoven fabric is preferably 10 μm to 1 cm, more preferably 10 μm to 1 mm, and even more preferably 20 μm to 250 μm.
The thickness of the nonwoven fabric is preferably thicker than the lower limit value from the viewpoint of production stability or strength, and is preferably thinner than the upper limit value from the viewpoint of productivity, uniformity, or resin impregnation.

The non-woven fabric of the present invention preferably has a porosity of 35 vol% or more, and more preferably 35 vol% or more and 60 vol% or less. When the porosity of the nonwoven fabric is small, the reaction is difficult to proceed when the above chemical modification is applied, or the matrix material such as resin is difficult to impregnate, and the unimpregnated portion remains when the composite is formed. Scattering occurs and haze increases. Moreover, when the non-woven fabric has a high porosity, when it is made into a composite, a sufficient reinforcing effect by cellulose fibers cannot be obtained, and the linear thermal expansion coefficient becomes large, which is not preferable.

The porosity here refers to the volume ratio of the voids in the nonwoven fabric, and the porosity can be determined from the area, thickness, and mass of the nonwoven fabric according to the following formula.
Porosity (vol%) = {1-B / (M × A × t)} × 100
Here, A is the area (cm ² ) of the nonwoven fabric, t (cm) is the thickness, B is the mass (g) of the nonwoven fabric, M is the density of cellulose, and M = 1.5 g / cm ³ is assumed in the present invention. To do. The film thickness of the nonwoven fabric is measured at 10 points at various positions of the nonwoven fabric using a film thickness meter (PDN-20 manufactured by PEACOK), and the average value is adopted.

Further, when obtaining the porosity of the nonwoven fabric in the composite, the porosity can also be obtained by performing image analysis of spectroscopic analysis or SEM observation of the cross section of the composite.

Air permeability of the nonwoven fabric of the present invention is not particularly limited since it depends on the basis weight, for example, when a basis weight of the sheet 50 g / ^{m 2} is preferably 100 to 20,000 sec / 100 cc.

(Manufacturing equipment)
In FIG. 5, the manufacturing apparatus used with the manufacturing method of the nonwoven fabric of this embodiment is shown. The manufacturing apparatus 1 of this embodiment includes a dewatering section 20, a drying section 40 provided on the downstream side of the dewatering section 20, and a winding section 60 provided on the downstream side of the drying section.

[Dehydration section]
The dewatering section 20 is a section for dewatering the fine fibrous cellulose-containing slurry 3a using the papermaking wire 10 to obtain the water-containing web 3b.
As the papermaking wire, woven or non-woven fabric such as plastic wire or metal wire, or paper can be used, and among these, non-woven fabric and paper are preferable.

The dewatering section 20 is provided with a feed reel 21 for feeding out the papermaking wire 10, a discharge unit 20a for the fine fibrous cellulose-containing slurry 3a, and a dehydrating unit 30 for the dispersion medium.
Two or more die heads 22 for discharging the fine fibrous cellulose-containing slurry 3a to the running paper-making wire 10 fed from the delivery reel 21 and disposed downstream of each die head 22 are discharged to the discharge unit 20a. And a plate 24 for leveling the upper surface of the fine fibrous cellulose-containing slurry 3a.
The discharge unit 20a and the dehydrating unit 30 are provided with

suction devices

26 and 32 for forcibly dehydrating the dispersion medium from the fine fibrous cellulose-containing slurry 3a. The

suction devices

26 and 32 are disposed below the paper making wire 10, and a plurality of suction holes (not shown) connected to a vacuum pump (not shown) are formed on the upper surface thereof. However, it is preferable that the suction hole is not formed on the upstream side of the suction device 26 and is a non-suction hole that is not connected to the vacuum pump. If the suction hole is formed on the upstream side, the surface of the coating film of the fine fibrous cellulose-containing slurry 3a may become rough. Further, since the amount of dewatering is reduced on the downstream side, the suction device 32 in the dewatering unit 30 may not have a hole formed on the downstream side.

[Drying section]
The drying section 40 is a section that obtains the nonwoven fabric 3c by drying the hydrous web 3b using a dryer.
The drying section 40 is provided with a first dryer 42 and a second dryer 52 configured by a cylinder dryer, and a felt cloth 44 disposed along the outer periphery of the first dryer 42 in a hood 49. The first dryer 42 is disposed on the upstream side of the second dryer 52. Further, the felt cloth 44 is endless and is circulated by a guide roll 46.
In the drying section 40, the water-containing web 3 b is transferred by the guide roll 48. Specifically, first, the surface A (hereinafter referred to as “application surface A”) of the water-containing web 3b on which the fine fibrous cellulose-containing slurry 3a is applied is in contact with the outer peripheral surface of the first dryer 42, and the water-containing web 3b. The surface B on which the fine fibrous cellulose-containing slurry 3a has not been applied (hereinafter referred to as “non-application surface B”) is transferred so as to be in contact with the felt cloth 44, and then the application surface A is the outer peripheral surface of the second dryer 52. To come in contact with.

[Winding section]
The winding section 60 is a section that separates the nonwoven fabric 3c from the papermaking wire 10 and winds it.
In the winding section 60, a pair of

separation rollers

62a and 62b for separating the nonwoven fabric 3c from the papermaking wire 10, a winding reel 64 for winding the nonwoven fabric 3c, and a used papermaking wire 10 are wound and collected. A collection reel 66 is provided.
The separation roller 62b is disposed on the papermaking wire 10 side, and the separation roller 62a is disposed on the nonwoven fabric 3c side.

(Production method)
The method for producing a nonwoven fabric according to this embodiment includes a dehydration step of dehydrating a slurry containing fine fibrous cellulose produced by the method for producing fine fibrous cellulose on a filter medium to obtain wet paper, and drying the wet paper It has a drying process for obtaining a nonwoven fabric and a winding process for winding the nonwoven fabric.

[Dehydration process]
In the dehydration step, the papermaking wire 10 is fed out from the delivery reel 21, the fine fibrous cellulose-containing slurry 3a is discharged from the die head 22 to the papermaking wire 10, and the upper surface of the fine fibrous cellulose-containing slurry 3a of the papermaking wire 10 is plated. Level by 24. At the same time, the

suction medium

26 and 32 sucks the dispersion medium contained in the fine fibrous cellulose-containing slurry 3a on the papermaking wire 10 and dehydrates it to obtain the water-containing web 3b.
In the dehydration process, when the running tension of the papermaking wire 10 is large, the papermaking wire 10 may be broken. Therefore, a wire used for normal papermaking is placed under the papermaking wire 10 for papermaking. The wire 10 may be supported.

Before supplying the fine fibrous cellulose-containing slurry 3a to the papermaking wire 10, the papermaking wire 10 may be preliminarily impregnated with water to be in a wet state. When the fine fibrous cellulose-containing slurry 3a is discharged onto the papermaking wire 10, the wrinkle may be generated due to water absorption of the wire. However, if it is made wet in advance, the generation of the wrinkle can be prevented.
Examples of means for bringing the papermaking wire 10 into a wet state include a water tank in which the papermaking wire 10 is immersed in water, or a water coating apparatus. As the water coating apparatus, a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, or the like can be used.

The fine fibrous cellulose-containing slurry 3a supplied to the papermaking wire 10 in the dehydration step is a liquid containing fine fibrous cellulose and water.
Moreover, the fine fibrous cellulose-containing slurry 3a may contain a resin emulsion. Here, the resin emulsion is an emulsion in which particles of natural resin or synthetic resin having a particle diameter of 0.001 to 10 μm are emulsified in water. The particulate resin contained in the resin emulsion is not particularly limited, but polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, poly (meth) acrylic acid alkyl ester polymer, ( (Meth) acrylic acid alkyl ester copolymer, poly (meth) acrylonitrile, polyester, polyurethane, polyamide, epoxy resin, oxetane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicon resin, diallyl phthalate resin, etc. Precursors, and resin emulsions such as monomers and oligomers constituting them; natural rubber, styrene-butadiene copolymer, or molecular chain ends of —SH, —CSSH, —SO ₃ H, — (COO) xM, — _(SO 3) x M, and Modified with at least one functional group selected from the group of CO—R (wherein M is a cation, x is an integer of 1 to 3 depending on the valence of M, and R is an alkyl group) Styrene-butadiene copolymer: acid-modified, amine-modified, amide-modified, or acrylic-modified styrene-butadiene copolymer; (meth) acrylonitrile-butadiene copolymer; polyisoprene; polychloroprene; styrene-butadiene- Methyl methacrylate copolymer; or styrene- (meth) acrylic acid alkyl ester copolymer. Further, polyethylene, polypropylene, polyurethane, ethylene-vinyl acetate copolymer or the like may be emulsified by a post-emulsification method. Two or more kinds of these resin emulsions can be contained.
In addition, when the slurry is dehydrated and dried, it can be obtained in a state in which fine fiber cellulose and a matrix material are contained in the nonwoven fabric 3c. You can also. In this case, two or more sheets may be laminated and cured.

Furthermore, the fine fibrous cellulose-containing slurry 3a can contain a cellulose coagulant. Examples of the cellulose coagulant include a water-soluble inorganic compound and a water-soluble organic compound 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, or a polymer obtained by polymerizing or copolymerizing a monomer containing a quaternary ammonium salt. .

Furthermore, the fine fibrous cellulose-containing slurry 3a can contain one or more materials such as a water-soluble organic polymer, an inorganic polymer, or a hybrid polymer of an organic polymer and an inorganic polymer.
Here, water-soluble polymers include polyvinyl alcohol, vinyl alcohol / ethylene copolymers, and those having a copolymer structure of vinyl alcohol and other monomers such as butyral; polyethylene oxide or alkyl-terminated ends thereof Nonionic water-soluble polymers such as polypropylene oxide or polybutyral resin (water-soluble grade); poly (meth) acrylic acid and poly (meth) acrylate; organic amino derivatives of poly (meth) acrylic acid Polyester; Polyethylene; Polyacrylamide; Acrylamide / sodium acrylate copolymer; Starch; Cationized starch; Phosphorylated starch; Carboxymethylcellulose; or Alginic acid and Alginate.
Examples of the inorganic polymer include ceramics such as glass, silicate material, and titanate material, and these can be formed, for example, by dehydration condensation reaction of alcoholate.

Furthermore, in order to improve the porosity of the resulting nonwoven fabric 3c, it is preferable to contain an organic solvent in the fine fibrous cellulose-containing slurry 3a, or to replace the moisture of the wet paper after dehydration with an organic solvent. When mixing the organic solvent, the mass ratio of water to the organic solvent (water: organic solvent) is preferably 100: 10 to 10: 100, more preferably 100: 30 to 30: 100, : 50 to 50: 100 is more preferable.
If the mixing amount of the organic solvent is not less than the lower limit, the porosity of the nonwoven fabric 3c can be sufficiently improved, and if it is not more than the upper limit, the increase in viscosity of the fine fibrous cellulose-containing slurry 3a can be suppressed. .
When the water content of the wet paper after the dehydration is replaced with an organic solvent, after the fine fibrous cellulose-containing slurry 3a is dehydrated, the wet paper prepared to have a solid content of 5% by mass to 30% by mass is combined with an organic solvent or water. The nonwoven fabric of the present invention can be obtained by impregnating a mixed solution of an organic solvent or applying the mixed solution, treating it by suction dehydration, and drying.

Examples of the organic solvent include alcohols, ketones, ethers, esters, aromatic compounds, hydrocarbons, cyclic hydrocarbons, and cyclic hydrocarbon derivatives.
Alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, t-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethyl-1-hexanol, benzyl alcohol, or phenol Monohydric alcohols such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, tri Dihydric alcohols such as ethylene glycol, 1,2-hexanediol, or 1,2-octanediol; dipropylene glycol methyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, or die Examples include glycol ethers such as tylene glycol monoethyl ether; diethylene glycol monoethyl ether acetate; ethylene glycol monomethyl ether acetate; polyethylene glycol; polypropylene glycol;
Examples of ethers include diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, or glymes such as diethylene glycol isopropyl methyl ether, 1,4-dioxane, Tetrahydrofuran, anisole, etc. are mentioned.
As ketones, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, t-butyl methyl ketone, diisopropyl ketone, butyl isopropyl ketone, isobutyl isopropyl ketone, diisobutyl ketone, 3-methyl-2-pentanone, 4-methyl-2- Examples include pentanone, 3-methyl-2-hexanone, 5-methyl-3-heptanone, 2-decanone, 3-decanone, 4-decanone, and 5-decanone.
Esters include methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, butyl acetoacetate, amyl acetate, amyl acetoacetate, hexyl acetate, hexyl acetoacetate, heptyl acetate, aceto Heptyl acetate, octyl acetate, octyl acetoacetate, methyl propionate, ethyl propionate, ethyl 2-hydroxypropionate, methyl butyrate, ethyl butyrate, methyl valerate, ethyl valerate, methyl hexanoate, ethyl hexanoate, methyl heptanoate , Ethyl heptanoate, methyl octanoate, ethyl octanoate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, oxalic acid Dimethyl, oxalic acid Ethyl, dimethyl malonate, diethyl malonate, dimethyl succinate, diethyl succinate, fatty acid esters such as dimethyl maleate or diethyl maleate, or methyl benzoate, or include an aromatic ester such as ethyl benzoate.
Examples of the aromatic compound include benzene, toluene, xylene, and ethylbenzene.
Examples of the hydrocarbon include n-hexane, n-heptane, and n-octane.
Examples of the cyclic hydrocarbon include cyclopentane, cyclohexane, and terpene.
Examples of the cyclic hydrocarbon derivative include cyclopentanol, cyclopentanone, cyclopentyl methyl ether, cyclohexanol, cyclohexanone, cyclohexanone dimethyl acetal, terpinolene, and terpineol.

The above organic solvents can be used in combination of two or more. Moreover, when mixing and using it, the ratio of the organic solvent which occupies in a mixed solution becomes like this. Preferably it is 40 mass% or more, More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more. The upper limit of the ratio of the organic solvent is not particularly limited. Two or more kinds of organic solvents can be used in the mixed solution. Furthermore, the organic solvent is preferably dissolved in water, but an organic solvent that does not dissolve in water can be emulsified and used as an emulsion.

The solid content concentration of the fine fibrous cellulose-containing slurry 3a is preferably 0.05 to 1.5% by mass, and more preferably 0.1 to 0.8% by mass. If the concentration of the fine fibrous cellulose-containing slurry 3a is equal to or higher than the lower limit value, sufficient production efficiency can be secured in the dehydration step, and if it is equal to or lower than the upper limit value, increase in viscosity is prevented and handling properties are improved. Can do.

In the dehydration step, the fine fibrous cellulose-containing slurry 3a is supplied so that the basis weight of the obtained nonwoven fabric 3c is preferably 10 to 900 g / m ² , more preferably 20 to 300 g / m ² . When the basis weight is equal to or more than the lower limit, the obtained nonwoven fabric 3c can be easily peeled from the papermaking wire 10 and is suitable for continuous production. On the other hand, when the basis weight is not more than the above upper limit value, the dehydration time can be further shortened, and the productivity can be further increased.

[Drying process]
In the drying step, first, the coated surface A is in contact with the outer peripheral surface of the first dryer 42, with the water-containing web 3b placed on the upper surface of the paper making wire 10 being approximately half the outer periphery of the heated first dryer 42. It winds and the dispersion medium which remained in the water-containing web 3b is evaporated. The evaporated dispersion medium evaporates from the felt cloth 44 through the pores of the papermaking wire 10.
Next, the water-containing web 3b is wound around about 3/4 of the outer peripheral surface of the heated second dryer 52 so that the coating surface A is in contact with the outer peripheral surface of the second dryer 52, and remains on the water-containing web 3b. Evaporate the dispersion medium.
In this way, the water-containing web 3b is dried to obtain the nonwoven fabric 3c.

[Winding process]
In the winding process, the papermaking wire 10 and the nonwoven fabric 3c are sandwiched between a pair of

separation rollers

62a and 62b, whereby the nonwoven fabric 3c is separated from the papermaking wire 10 and transferred to the surface of one separation roller 62a. Thereafter, the nonwoven fabric 3 c is pulled away from the surface of the separation roller 62 a and is taken up by the take-up reel 64. At the same time, the used paper making wire 10 is taken up by the collection reel 66.

(Other embodiments)
In the manufacturing method of the nonwoven fabric of this invention, the said manufacturing apparatus 1 does not need to be used. For example, the papermaking wire 10 may be transported on an endless or endless belt.
Moreover, in the manufacturing method of the nonwoven fabric of this invention, the paper machine used when manufacturing a general paper can be applied easily. As the paper machine, in addition to a continuous paper machine such as a long-mesh type, a circular net type, or an inclined type, a multi-layered paper machine combining these can be applied.

(Function and effect)
The method for producing the nonwoven fabric is a method for producing a nonwoven fabric by dehydrating the fine fibrous cellulose-containing slurry 3a produced by the production method above and drying it to improve the yield of the nonwoven fabric relative to the fiber raw material. Can do.

Moreover, since the nonwoven fabric obtained by the said nonwoven fabric manufacturing method has a moderate space | gap, the resin impregnation property of a matrix material when obtaining a composite_body | complex with a matrix material is favorable. Furthermore, when the nonwoven fabric of this invention is used, the yellowishness of the composite obtained will become low, sufficient reinforcement effect will be expressed, and linear thermal expansion will become low.
Moreover, the nonwoven fabric of this invention can also be used alone. For example, it can be suitably used for filter members, battery separators, and the like by taking advantage of the fine structure unique to fine fibers.

<Composite>
The composite of the present invention contains fine fibrous cellulose and a matrix material.
(Matrix material)
In the present invention, the matrix material is a material that fills voids between fine fibrous celluloses or, when fine fibrous cellulose forms a nonwoven fabric, preferably a polymer material.
Polymer materials suitable as the matrix material include thermoplastic resins, thermosetting resins (cured products obtained by polymerization and curing of thermosetting resin precursors by heating), or photocurable resins (precursors of photocurable resins). Is a cured product obtained by polymerization and curing upon irradiation with radiation (such as ultraviolet rays or electron beams).
These may be one kind or two or more kinds.

Although it does not specifically limit as a thermoplastic resin, Styrenic resin, acrylic resin, aromatic polycarbonate resin, aliphatic polycarbonate resin, aromatic polyester resin, aliphatic polyester resin, aliphatic polyolefin Resin, cyclic olefin resin, polyamide resin, polyphenylene ether resin, thermoplastic polyimide resin, polyacetal resin, polysulfone resin, or amorphous fluorine resin.

The thermosetting resin is not particularly limited, but epoxy resin, acrylic resin, oxetane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicon resin, polyurethane resin, diallyl phthalate resin, etc. Is mentioned.

The photocurable resin is not particularly limited, and examples thereof include the epoxy resin, acrylic resin, or oxetane resin exemplified as the above-described thermosetting resin.

Furthermore, specific examples of the thermoplastic resin, thermosetting resin, or photocurable resin include those described in JP-A-2009-299043.

The matrix material is preferably an amorphous synthetic polymer having a high glass transition temperature (Tg) from the viewpoint of obtaining a composite having excellent transparency and high durability. The degree of amorphousness is preferably 10% or less, and particularly preferably 5% or less in terms of crystallinity. Further, Tg is preferably 110 ° C. or higher, particularly 120 ° C. or higher, particularly 130 ° C. or higher. If Tg is low, there is a risk of deformation when touched with hot water, for example, which causes a practical problem. The Tg of the matrix material is obtained by measurement by the DSC method, and the crystallinity can be calculated from the density of the amorphous part and the crystalline part.

When the composite of the present invention is used for transparent applications such as optical materials, it is preferable to use a transparent resin such as an acrylic resin, an aromatic polycarbonate resin, or an aliphatic polycarbonate resin as the matrix material.
In order to obtain a low water-absorbing composite, the matrix material preferably has few hydrophilic functional groups such as a hydroxy group, a carboxy group, or an amino group.

The content of fine fibrous cellulose in the composite of the present invention is 1% by mass or more and 99% by mass or less based on the total solid content of the composite, and the content of the matrix material is based on the total solid content of the composite. It is preferable that it is 1 mass% or more and 99 mass% or less.
In order to exhibit low linear thermal expansibility, the content of fine fibrous cellulose is 1% by mass or more with respect to the total solid content of the composite, and the content of the matrix material is 99% with respect to the total solid content of the composite. In order to express transparency, the content of fine fibrous cellulose is 99% by mass or less with respect to the total solid content of the composite, and the content of the matrix material is the total solid content of the composite. It is preferable that it is 1 mass% or more with respect to.
More preferably, the content of fine fibrous cellulose is 2% by mass or more and 90% by mass or less with respect to the total solid content of the composite, and the matrix material is 10% by mass or more and 98% by mass or more with respect to the total solid content of the composite. More preferably, the content of the fine fibrous cellulose is 5% by mass or more and 80% by mass or less, and the content of the matrix material is 20% by mass or more and 95% by mass or less. In particular, in the composite of the present invention, the content of fine fibrous cellulose is 70% by mass or less with respect to the total solid content of the composite and the content of the matrix material is 30% by mass or more with respect to the total solid content of the composite. Furthermore, it is preferable that the content of the fine fibrous cellulose is 60% by mass or less and the content of the matrix material is 40% by mass or more. Further, the content of the fine fibrous cellulose is 10% by mass or more and the content of the matrix material is 90% by mass or less. Furthermore, the content of the fine fibrous cellulose is 15% by mass or more and the content of the matrix material is 85% by mass. Hereinafter, it is preferable that the content of the fine fibrous cellulose fiber is 20% by mass or more and the content of the matrix material is 80% by mass or less.

The contents of the fine fibrous cellulose and the matrix material in the composite can be determined, for example, from the mass of the nonwoven fabric before the composite and the mass of the composite. Alternatively, the composite can be immersed in a solvent in which the matrix material is soluble to remove only the matrix material, and can be determined from the mass of the remaining fibers. In addition, the functional group derived from a matrix material or a cellulose fiber can also be quantified and determined by using a specific gravity of the matrix material, NMR, or IR.

The composite of the present invention may be a flat film (film) or a flat plate, a film having a curved surface or a plate, or other three-dimensional shape. .
When the composite of the present invention is a film or a plate, the thickness is preferably 10 μm or more and 10 cm or less. Strength can be maintained by using a composite having such a thickness.
The thickness of the composite is more preferably 50 μm or more and 1 cm or less, and further preferably 80 μm or more and 250 μm or less. Further, the thickness is not necessarily uniform, and may be partially different.

Further, when the composite of the present invention is in the form of a film or a plate, two or more sheets may be stacked to form a laminate. Moreover, you may laminate | stack the composite sheet containing a cellulose fiber, and the resin sheet which does not contain a cellulose. A thick film can be formed by applying a heat press treatment to the laminate. A thick film composite can be suitably used as a glazing or structural material.

The composite of the present invention may be laminated with an inorganic film on the surface according to the application. Examples of the inorganic material constituting the inorganic film include metals such as platinum, silver, aluminum, gold, and copper, silicon, ITO, SiO ₂ , SiN, SiOxNy, ZnO, and the like, or TFT. These combinations and film thicknesses can be designed arbitrarily.

(Production method of composite)
There is no restriction | limiting in particular as a method of manufacturing a composite_body | complex, For example, a composite_body | complex can be obtained with the following method.

(A) A method in which a nonwoven fabric is impregnated with a plastic resin precursor and polymerized.
(B) A method in which a non-woven fabric is impregnated with a thermosetting resin precursor or a photocurable resin precursor and polymerized and cured.
(C) After impregnating a nonwoven fabric with a resin solution (a solution containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor) and drying , A method of adhering with a heating press or the like and polymerizing and curing as desired.
(D) A method in which a nonwoven fabric is impregnated with a melt of a thermoplastic resin and adhered by a hot press or the like.
(E) A method in which thermoplastic resin sheets and non-woven fabrics are alternately arranged and adhered with a hot press or the like.
(F) A method in which a liquid thermoplastic resin precursor, a thermosetting resin precursor, or a photocurable resin precursor is applied to one side or both sides of a non-woven fabric and polymerized and cured.
(G) Applying a resin solution (a solution containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor) to one side or both sides of a nonwoven fabric Then, after removing the solvent, a method of polymerizing and curing as desired.
(H) a fine fibrous cellulose-containing slurry and a monomer solution or dispersion (a solution containing one or more solutes or dispersoids selected from a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor, or (Dispersion liquid) and then solvent removal and polymerization curing.
(I) A method of removing the solvent after mixing the fine fibrous cellulose-containing slurry and the polymer solution or dispersion (thermoplastic resin solution or dispersion).

(A) The nonwoven fabric is impregnated with a liquid thermoplastic resin precursor and polymerized. The nonwoven fabric is impregnated with a polymerizable monomer or oligomer, and the monomer is polymerized by heat treatment or the like to obtain a cellulose fiber composite. A method is mentioned. Generally, a polymerization catalyst used for polymerization of monomers can be used as a polymerization initiator.

(B) As a method of polymerizing and curing a nonwoven fabric by impregnating a thermosetting resin precursor or a photocurable resin precursor, a thermosetting resin precursor such as an epoxy resin monomer, or a photocurable resin such as an acrylic resin monomer. A method of obtaining a cellulose fiber composite by impregnating a non-woven fabric with a mixture of a resin precursor and a curing agent and curing the thermosetting resin precursor or the photocurable resin precursor with heat or radiation or the like.

(C) After impregnating a nonwoven fabric with a resin solution (a solution containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor) and drying Examples of the method of causing the resin to adhere by heating press or the like and polymerizing and curing as desired include a method in which the resin is dissolved in a solvent in which the resin is dissolved, the nonwoven fabric is impregnated with the solution, and dried to obtain a cellulose fiber composite. . In this case, there is a method of obtaining a higher-performance cellulose fiber composite by adhering the voids in which the solvent is dried by a heating press after drying. In the case of a photo-curing resin, polymerization curing by radiation or the like is further performed as desired.
Here, the solvent for dissolving the resin may be selected according to the solubility of the resin.

(D) As a method of impregnating a nonwoven fabric with a melt of a thermoplastic resin and closely adhering with a heating press or the like, the thermoplastic resin is dissolved by heat treatment at a glass transition temperature or higher or a melting point or higher, and impregnated into the nonwoven fabric. The method of obtaining a cellulose fiber composite by sticking with a heating press etc. is mentioned. The heat treatment is preferably performed under pressure, and the use of equipment having a vacuum heating press function is effective.

(E) As a method of alternately arranging the thermoplastic resin sheet and the nonwoven fabric and closely adhering them with a heating press or the like, placing a thermoplastic resin film or sheet on one side or both sides of the nonwoven fabric, and heating or pressing as desired And a method of laminating a thermoplastic resin and a nonwoven fabric. In this case, an adhesive or a primer may be applied to the surface of the nonwoven fabric and bonded together. A method of passing between two pressurized rolls or a method of pressing in a vacuum state can be used so that bubbles are not embraced at the time of bonding.

(F) As a method of applying and curing a liquid thermoplastic resin precursor, a thermosetting resin precursor or a photocurable resin precursor on one side or both sides of the nonwoven fabric, a thermal polymerization initiator is applied to one side or both sides of the nonwoven fabric. After applying a thermosetting resin precursor formulated with a photocuring resin precursor formulated with a photopolymerization initiator on one side or both sides of a nonwoven fabric, by curing by heating and curing both And a method of curing by irradiating with radiation such as ultraviolet rays.
Alternatively, after applying a heat or photo-curing resin precursor to the nonwoven fabric, the nonwoven fabric may be further laminated and then cured.

(G) A resin solution (a solution containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor) is applied to one side or both sides of the nonwoven fabric. Then, after removing the solvent, as a method of compounding by polymerizing and curing as desired, a resin solution in which a resin soluble in the solvent is dissolved is prepared, applied to one or both sides of the nonwoven fabric, and the solvent is removed by heating. The method of removing is mentioned. In the case of a photo-curing resin, polymerization curing by radiation or the like is further performed as desired.
A solvent for dissolving the resin may be selected according to the solubility of the resin.

(H) a fine fibrous cellulose-containing slurry and a monomer solution or dispersion (a solution containing one or more solutes or dispersoids selected from a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor, or As a method of compounding by mixing the dispersion liquid) and then passing through the steps of solvent removal and polymerization and curing, a solution in which a monomer soluble in the solvent or a dispersion liquid is prepared, and fine fibrous cellulose is prepared. Mix the slurry. At this time, the cellulose fibers are preferably defibrated by using an organic solvent in advance as a dispersion medium (solvent), or when defibrated in water, the water is preferably replaced with an organic solvent. A cellulose fiber composite can be obtained by polymerizing and curing the monomer in this mixed solution or polymerizing and curing the monomer after removing the solvent.

(I) After mixing the fine fibrous cellulose-containing slurry and the polymer solution or dispersion (thermoplastic resin solution or dispersion), the solvent is removed to form a composite. Alternatively, a dispersion is prepared and mixed with the fine fibrous cellulose slurry. At this time, the cellulose fibers are preferably defibrated by using an organic solvent in advance as a dispersion medium (solvent), or when defibrated in water, the water is preferably replaced with an organic solvent. A cellulose fiber composite can be obtained by removing the solvent of the mixed solution.

In the above thermoplastic resin precursor, thermosetting resin precursor, and photocurable resin precursor, a chain transfer agent, an ultraviolet absorber, a filler other than cellulose, or a silane coupling agent is appropriately blended. Or a composition (hereinafter referred to as “curable composition”).

When the curable composition contains a chain transfer agent, the reaction can proceed uniformly. As the chain transfer agent, for example, a polyfunctional mercaptan compound having two or more thiol groups in the molecule can be used. By using a polyfunctional mercaptan compound, moderate toughness can be imparted to the cured product.
Examples of mercaptan compounds include pentaerythritol tetrakis (β-thiopropionate), trimethylolpropane tris (β-thiopropionate), or tris [2- (β-thiopropionyloxyethoxy) ethyl] triisocyanurate. It is preferable to use 1 type (s) or 2 or more types.
When a chain transfer agent is contained in the curable composition, the chain transfer agent is usually contained in a proportion of 30% by mass or less with respect to the total of radically polymerizable compounds in the curable composition.

When the curable composition contains an ultraviolet absorber, coloring can be prevented. As an ultraviolet absorber, it selects from a benzophenone series ultraviolet absorber and a benzotriazole type ultraviolet absorber, for example, The ultraviolet absorber may use 1 type and may use 2 or more types together.
When an ultraviolet absorber is contained in the curable composition, the ultraviolet absorber is usually contained at a ratio of 0.01 to 1 part by mass with respect to a total of 100 parts by mass of radically polymerizable compounds in the curable composition. .

Examples of the filler include inorganic particles and organic polymers. Specifically, inorganic particles such as silica particles, titania particles, or alumina particles, transparent cycloolefin polymer particles such as Zeonex (Nippon Zeon) and Arton (JSR), or general-purpose such as polycarbonate and polymethyl methacrylate Examples include thermoplastic polymer particles. Among these, use of nano-sized silica particles is preferable because transparency can be maintained. In addition, when polymer particles having a structure similar to that of the ultraviolet curable monomer are used as the filler, the polymer can be dissolved to a high concentration, which is preferable.

Examples of the silane coupling agent include γ-((meth) acryloxypropyl) trimethoxysilane, γ-((meth) acryloxypropyl) methyldimethoxysilane, and γ-((meth) acryloxypropyl) methyldiethoxy. Examples include silane, γ-((meth) acryloxypropyl) triethoxysilane, and γ- (acryloxypropyl) trimethoxysilane. These have a (meth) acryl group in the molecule and are preferable because they can be copolymerized with other monomers.
When the curable composition contains a silane coupling agent, the silane coupling agent is usually 0.1 to 50% by mass, preferably 1 to 20%, based on the total of radically polymerizable compounds in the curable composition. It is made to contain so that it may become mass%. If the blending amount is too small, the effect of containing it is not sufficiently obtained, and if it is too large, optical properties such as transparency of the cured product may be impaired.

The curable composition can be polymerized and cured by a known curing method to obtain a cured product.
Examples of the curing method include thermal curing and radiation curing, and radiation curing is preferable. Examples of the radiation include infrared rays, visible rays, ultraviolet rays, electron beams, and the like, but light that is an electromagnetic wave having a wavelength of 1 to 1000 nm is preferable. More preferred is an electromagnetic wave having a wavelength of about 200 nm to 450 nm, and still more preferred is an ultraviolet ray having a wavelength of 300 to 400 nm.

As a specific curing method of the curable composition, a method in which a thermal polymerization initiator that generates radicals and acids by heating is added to the curable composition in advance and polymerized by heating (hereinafter referred to as “thermal polymerization”). In some cases, a photopolymerization initiator that generates radicals and acids by radiation such as ultraviolet rays is added to the curable composition in advance and polymerized by irradiation with radiation (preferably light) (hereinafter referred to as “light”). There may be referred to as “polymerization”.), Or a method in which both a thermal polymerization initiator and a photopolymerization initiator are added in advance and polymerized by a combination of heat and light.

In the case of polymerization and curing by irradiation, the amount of radiation to be irradiated is arbitrary as long as the photopolymerization initiator is in a range that generates radicals. However, when the amount is extremely small, the polymerization becomes incomplete, so that the heat resistance or mechanical properties of the cured product are not fully expressed. . Therefore, depending on the composition of the monomer and the type and amount of the photopolymerization initiator, UV of 300 to 450 nm is preferably in the range of 0.1 to 200 J / cm ² , more preferably in the range of 1 to 20 J / cm ² . Irradiate with.
Further, it is more preferable to irradiate the radiation in two or more 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 having smaller birefringence can be obtained.
Specific examples of the lamp used for radiation irradiation include a metal halide lamp, a high pressure mercury lamp lamp, an ultraviolet LED lamp, and an electrodeless mercury lamp.

Photopolymerization and thermal polymerization may be performed at the same time in order to quickly complete the polymerization and curing. In this case, the curable composition is heated at a temperature in the range of 30 to 300 ° C. at the same time as the irradiation with radiation to be cured. In addition, a thermal polymerization initiator may be added to the curable composition in order to complete the polymerization, but when added in a large amount, the birefringence of the cured product is increased and the hue is deteriorated. Therefore, the addition amount of the thermal polymerization initiator is preferably 0.1 to 2% by mass, and more preferably 0.3 to 1% by mass with respect to the total of the curable monomer components.

Examples of the thermal polymerization initiator used for thermal polymerization include hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxycarbonate, peroxyketal, and ketone peroxide. Specifically, benzoyl peroxide, diisopropyl peroxy carbonate, t-butyl peroxy (2-ethylhexanoate) dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoate, t-butyl hydroperoxide Side, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, or the like can be used. These polymerization initiators may be used alone or in combination of two or more.
When thermal polymerization is initiated at the time of light irradiation, it becomes difficult to control the polymerization. Therefore, the thermal polymerization initiator preferably has a 1 minute half-life temperature of 120 ° C. or higher.

As the photopolymerization initiator used for photopolymerization, a photoradical generator or a photocationic polymerization initiator is usually used. A photoinitiator may be used independently or may use 2 or more types together.

As the photoradical generator, known compounds that can be used for this purpose can be used. Examples include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, or 2,4,6-trimethylbenzoyldiphenylphosphine oxide. . Among these, benzophenone or 2,4,6-trimethylbenzoyldiphenylphosphine oxide is preferable.

The photocationic polymerization initiator is a compound that initiates cationic polymerization by irradiation with radiation such as ultraviolet rays or electron beams, and includes the following.

For example, aromatic sulfonium salts include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (diphenylsulfone). Nio) phenyl] sulfide bishexafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoro, diphenyl-4- (phenylthio) ) Phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenyl Rufonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di ( 4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimony Bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonylio) phenyl] sulfide tetrafluoroborate, or bis [4- (di (4 (2-hydroxyethoxy)) phenylsulfonyl O) phenyl] sulfide tetrakis (pentafluorophenyl) borate, and the like.

Aromatic iodonium salts include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecyl) Phenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluorovolley , Or 4-methylphenyl-4- (1-methylethyl) phenyl iodonium tetrakis (pentafluorophenyl) borate, and the like.

Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, and the like.

Aromatic ammonium salts include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2- Cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, 1- (naphthylmethyl) -2- Examples thereof include cyanopyridinium tetrafluoroborate and 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate. (2,4-Cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron salt includes (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron. (II) hexafluorophosphate, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron (II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl) [(1-Methylethyl) benzene] -iron (II) tetrafluoroborate, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron (II) tetrakis (pentafluorophenyl) Examples include borate.

Commercially available products of these cationic photopolymerization initiators include, for example, UVI6990, UVI6979 manufactured by Union Carbide, SP-150, SP-170, or SP-172 manufactured by ADEKA, Irgacure 261 manufactured by Ciba Geigy, or Irgacure 250, Rhodia SILPI 2074 or JMF-2456 manufactured by Rhodia, or Sun-Aid SI-60L, SI-80L, SI-100L, SI-110L, SI-180L, or SI-100L manufactured by Sanshin Chemical Industry Co., Ltd. .

Furthermore, in addition to the cationic photopolymerization initiator, a curing agent for curing the cationic polymerizable monomer may be added. Examples of the curing agent include amine compounds, compounds such as polyaminoamide compounds synthesized from amine compounds, tertiary amine compounds, imidazole compounds, hydrazide compounds, melamine compounds, acid anhydrides, phenolic compounds, thermal latent cationic polymerization catalysts. Or dicyanamide and derivatives thereof. These hardening | curing agents may be used independently and 2 or more types may be used together. Among these, as the heat latent cationic polymerization catalyst, Adeka Opton CP-66 or CP-77 (manufactured by ADEKA Co., Ltd.) or Sun-Aid SI-15, SI-20, SI-25, SI-40, SI -45, SI-47, SI-60, SI-80, SI-100, SI-100L, SI-110L, SI-145, SI-150, SI-160, or SI-180L (Sanshin Chemical Industry Co., Ltd. )).

Also, a photosensitizer can be added. Specific examples include pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone, and benzoflavin. Examples of commercially available photosensitizers include Adekapitomer SP-100 (manufactured by ADEKA Corporation).

The component amount of the photopolymerization initiator is preferably 0.001 part by mass or more and 0.01 part by mass or more when the total amount of polymerizable compounds in the curable composition is 100 parts by mass. Is more preferably 0.05 parts by mass or more. Further, the amount of the component of the photopolymerization initiator is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, and further preferably 0.1 parts by mass or less.
That is, the range of the component amount of the photopolymerization initiator is preferably 0.001 to 5 parts by mass, and 0.01 to 2 parts by mass when the total amount of polymerizable compounds in the curable composition is 100 parts by mass. Is more preferable, and 0.05 to 0.1 parts by mass is even more preferable.
However, when the photopolymerization initiator is a photocationic polymerization initiator, it is 0.01 parts by mass or more, preferably 0.1 parts by mass or more, more preferably, with respect to 100 parts by mass of the total amount of the cationic polymerizable monomer. 0.5 parts by mass or more, usually 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 1 part by mass or less.
That is, when the photopolymerization initiator is a photocationic polymerization initiator, the component amount of the photopolymerization initiator ranges from 0.01 to 10 parts by mass with respect to 100 parts by mass of the total amount of the cation polymerizable monomer. Preferably, 0.1 to 5 parts by mass is more preferable, and 0.5 to 1 part by mass is further preferable. When the addition amount of the photopolymerization initiator is too large, the polymerization proceeds rapidly, not only increasing the birefringence of the resulting cured product but also deteriorating the hue. For example, when the concentration of the photopolymerization initiator is 5 parts by mass, absorption of the photopolymerization initiator causes light to not reach the side opposite to the irradiation of ultraviolet rays, resulting in an uncured part. Further, it is colored yellow and the hue is markedly deteriorated. On the other hand, if the amount is too small, the polymerization may not proceed sufficiently even if ultraviolet irradiation is performed.

In the production of the composite, when the nonwoven fabric of the present invention and the matrix material are composited, it is preferable to perform the above-described chemical modification treatment on the nonwoven fabric before the composite of the matrix material.
When chemically modifying the fine fibrous cellulose of the nonwoven fabric, the nonwoven fabric may be substituted with an organic solvent such as alcohol and dried, and then the chemical modification may be performed, or the chemical modification may be performed without drying. Since the reaction rate of chemical modification becomes faster after drying, it is preferable. Drying may be air drying, vacuum drying, or pressure drying. It can also be heated.

When the nonwoven fabric is chemically modified, it is preferable to thoroughly wash after the chemical modification in order to terminate the reaction. If the unreacted chemical modifier remains, it is not preferable because it causes coloring later or becomes a problem when it is combined with the resin. In addition, after washing sufficiently, it is preferable to further replace with an organic solvent such as alcohol. In this case, the nonwoven fabric can be easily replaced by immersing it in an organic solvent such as alcohol.

Moreover, when chemically modifying a nonwoven fabric, the nonwoven fabric is normally dried after chemical modification. This drying may be air drying, vacuum drying, pressure drying, or heat drying.
When heating at the time of drying, the temperature is preferably 50 ° C or higher, more preferably 80 ° C or higher, 250 ° C or lower is more preferable, and 150 ° C or lower is more preferable.
That is, the temperature range when heating during drying is preferably 50 to 250 ° C, more preferably 80 to 150 ° C.
If the heating temperature is too low, drying may take time or drying may be insufficient. If the heating temperature is too high, the nonwoven fabric may be colored or decomposed.
In addition, when pressurizing, the pressure (gauge pressure) is preferably 0.01 MPa or more, more preferably 0.1 MPa or more, and preferably 5 MPa or less, more preferably 1 MPa or less.
That is, the range of pressure (gauge pressure) when pressurizing is preferably 0.01 to 5 MPa, and more preferably 0.1 to 15 MPa.
If the pressure is too low, drying may be insufficient, and if the pressure is too high, the nonwoven fabric may be crushed or decomposed.

(Physical properties of the composite)
Next, the physical properties of the composite of the present invention will be described.

The composite of the present invention is a fiber composite having a thickness of 100 μm, heated at 190 ° C. with an oxygen partial pressure of 0.006 MPa or less for 1 hour, and then the yellowness (YI value) measured according to JIS standard K7105 is 30 or less. It is preferable that The yellowness is more preferably 25 or less.
The yellowness of the composite can be measured, for example, using a color computer manufactured by Suga Test Instruments.
The yellowness of the composite can be reduced by chemically modifying the cellulose fibers or using a highly transparent matrix material.

In the composite of the present invention, fibers having a fiber diameter thinner than the wavelength of visible light are used. Therefore, if a highly transparent material is used for the matrix material, a composite having high transparency, that is, having a low haze is obtained. Can do. The haze value of the composite is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less, as measured according to JIS standard K7136 for a 100 μm thick composite. The following is particularly preferable.
The haze of the composite can be measured, for example, with a haze meter manufactured by Suga Test Instruments, and the value of C light is used.

The composite of the present invention has a low water absorption, but in a 100 μm thickness, the water absorption measured according to JIS standard K7209 (D method) is preferably 1% or less, 0.8 % Or less is more preferable, 0.5% or less is further preferable, and 0.3% or less is particularly preferable.
When the water absorption rate exceeds 1%, the composite dehydrated in the processing process is undesirably stretched by absorbing moisture in the air when left in the air and causing dimensional deformation.

The composite of the present invention has a thickness of 100 μm, and the total light transmittance measured in accordance with JIS standard K7105 in the thickness direction is preferably 60% or more, more preferably 70% or more, more preferably 80%. More preferably, it is 82% or more, more preferably 84% or more, still more preferably 86% or more, particularly preferably 88% or more, and particularly preferably 90% or more. If this total light transmittance is less than 60%, it becomes translucent or opaque, and it may be difficult to use it in applications requiring transparency. The total light transmittance can be measured, for example, using a Suga Test Instruments haze meter, and the value of C light is used.

In the composite of the present invention having a thickness of 100 μm, the parallel light transmittance measured in accordance with JIS standard K7105 in the thickness direction is 57% or more, further 70% or more, particularly 80% or more, especially 89%. The above is preferable. If the parallel light transmittance is less than 57%, the amount of scattered light is increased and haze is increased. For example, in an organic EL device application, the pixel becomes unclear and the color is blurred or blurred. The parallel light transmittance can be measured, for example, using a Suga Test Instruments haze meter, and the value of C light is used.

The composite of the present invention can easily have a low coefficient of linear thermal expansion, but preferably has a coefficient of linear thermal expansion of 1 to 50 ppm / K. The linear thermal expansion coefficient of the composite of the present invention is more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less. Further, the linear thermal expansion coefficient is preferably 1 ppm / K or more, and more preferably 5 ppm / K or more.
That is, the range of the linear thermal expansion coefficient is preferably 1 to 50 ppm / K, more preferably 5 to 30 ppm / K, and still more preferably 5 to 20 ppm / K.
For example, in a substrate application, since the linear thermal expansion coefficient of an inorganic thin film transistor is about 15 ppm / K, when the linear thermal expansion coefficient of the composite exceeds 50 ppm / K, two layers are combined in an inorganic film. The difference in coefficient of linear thermal expansion between layers becomes large, and cracks and the like are generated. The linear thermal expansion coefficient is measured by the method described in the section of Examples described later.

In the composite of the present invention, the matrix material is filled in the gaps between the fine fibrous celluloses, but when the nonwoven fabric is used, the matrix material is filled in the gaps in the nonwoven fabric. Therefore, the volume ratio of the matrix material filling portion is substantially equal to the porosity of the nonwoven fabric.

The tensile strength of the composite of the present invention is preferably 40 MPa or more, more preferably 100 MPa or more. If the tensile strength is lower than 40 MPa, sufficient strength cannot be obtained, which may affect the use of a structural material or the like to which a force is applied.

The composite of the present invention has a tensile modulus of preferably 0.2 to 100 GPa, more preferably 1 to 100 GPa. When the tensile elastic modulus is lower than 0.2 GPa, sufficient strength cannot be obtained, which may affect the use in applications where force is applied such as structural materials.
In particular, in a display substrate application, there is a suitable range for the tensile elastic modulus of the substrate. If the tensile elastic modulus of the substrate is low, the substrate is bent by its own weight, and it becomes difficult to form a smooth surface. For this reason, transistors and other elements cannot be formed with high accuracy.
On the other hand, if the tensile elastic modulus is too high, it becomes hard and brittle, causing problems such as cracking of the substrate itself.

The composite of the present invention has a low linear thermal expansion coefficient, high elasticity, and high strength. Taking advantage of the characteristics, the composite of the present invention can be used as a structural material. In particular, it is suitably used as automobile materials such as glazing, interior materials, outer plates, or bumpers, personal computer casings, home appliance parts, packaging materials, building materials, civil engineering materials, marine products, or other industrial materials.
In the composite of the present invention, when a fiber width of 30 nm or less, particularly preferably 20 nm or less is used as the fine fibrous cellulose, and the transparent resin is used as the matrix material, the transparency of the composite is increased and haze is reduced. Become. In the composite of the present invention, the water absorption can be lowered by appropriately selecting a matrix material. Among the composites of the present invention, those having high transparency, small haze, high strength, and low water absorption are excellent in optical characteristics. It is suitable as a display, a substrate or a panel. Moreover, it is suitable for substrates for solar cells such as silicon-based solar cells or dye-sensitized solar cells. For use as a substrate, it may be laminated with a barrier film, ITO, TFT or the like. Moreover, it is suitably used for window materials for automobiles, window materials for railway vehicles, window materials for houses, window materials for offices, factories and the like. As the window material, a film such as a fluorine film or a hard coat film, or an impact-resistant or light-resistant material may be laminated as desired.

The method for producing fine fibrous cellulose according to another aspect of the present invention includes:
Drying the fiber raw material containing cellulose to obtain a dry pulp having a moisture content of 10% or less based on the dry weight of the fiber raw material, and maleic anhydride, succinic anhydride, and phthalic anhydride, or these The dried pulp is treated with at least one carboxylic acid compound selected from the group consisting of derivatives of carboxy group to introduce a carboxy group into cellulose, and a carboxy group is introduced after completion of the carboxy group introduction step. A group consisting of cellulose aqueous solution, aqueous solution of potassium hydroxide, aqueous solution of ammonia, aqueous solution of tetramethylammonium hydroxide, aqueous solution of tetraethylammonium hydroxide, aqueous solution of tetrapropylammonium hydroxide, and aqueous solution of tetrabutylammonium hydroxide. Ri and alkali treatment step of treating at least one alkali solution selected preferably has a fibrillation treatment step of fibrillation treatment the cellulose after the alkali treatment.

According to still another aspect of the present invention, there is provided a method for producing fine fibrous cellulose comprising at least one carboxylic acid compound selected from the group consisting of maleic anhydride, succinic anhydride, phthalic anhydride or derivatives thereof. Including the carboxy group introduction step of introducing a carboxy group into cellulose by treating a fiber raw material containing 10% by mass or less of the moisture content of the fiber raw material, and introducing the carboxy group after completion of the carboxy group introduction step. Cellulose is selected from the group consisting of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrapropylammonium hydroxide aqueous solution, and tetrabutylammonium hydroxide aqueous solution. And alkali treatment step of treating at least one alkali solution that preferably has a fibrillation treatment step of fibrillation treatment the cellulose after the alkali treatment.

(Example 1)
Hardwood kraft pulp (LBKP) was dried at 105 ° C. for 3 hours to obtain a dry pulp having a water content of 3% by mass or less. Next, 4 g of dried pulp and 4 g of maleic anhydride (100 parts by mass with respect to 100 parts by mass of dried pulp) were filled in an autoclave and treated at 150 ° C. for 2 hours.
Next, the pulp treated with maleic anhydride was washed with 500 mL of water three times, and then ion-exchanged water was added to prepare 490 mL of slurry.
Next, while stirring the slurry, 10 mL of 4N aqueous sodium hydroxide solution was added little by little to adjust the pH of the slurry to 12 to 13, and the pulp was alkali treated. Thereafter, the pulp after alkali treatment was washed with water until the pH became 8 or less.
Subsequently, ion-exchanged water was added to the pulp after the alkali treatment to prepare a slurry having a solid content concentration of 0.5% by mass. The slurry was defibrated for 30 minutes using a defibrating apparatus (Cleamix-2.2S, manufactured by MTechnic Co., Ltd.) at 21500 rpm, and finally a cooling / high-speed centrifuge (Kokusan Co., Ltd.). Manufactured by H-2000B) and centrifuged at 12000 G for 10 minutes, and the supernatant was recovered to obtain a defibrated pulp slurry.
When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed that the cellulose was a fine fibrous cellulose having a width of about 4 nm (see FIG. 1). Moreover, the cellulose maintained the cellulose I type crystal | crystallization by X-ray diffraction, and the crystallinity was 84%. Measurement of an infrared absorption spectrum by FT-IR showed absorption based on a carboxy group in the vicinity of 1580 and 1720 cm ⁻¹ , confirming the addition of maleic acid.

(Example 2)
A defibrated pulp slurry was obtained in the same manner as in Example 1 except that succinic anhydride was used instead of maleic anhydride. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed that the cellulose was a fine fibrous cellulose having a width of about 4 nm (see FIG. 2). Moreover, by X-ray diffraction, the cellulose maintained the cellulose I type crystal | crystallization and the crystallinity was 82%. The addition of succinic acid was confirmed by measurement of the infrared absorption spectrum by FT-IR.

(Example 3)
Example 1 except that the amount of maleic anhydride added was changed to 12 g (300 parts by mass with respect to 100 parts by mass of dried pulp), the treatment time with maleic anhydride was changed to 1 hour, and the washing medium was changed to acetone. A defibrated pulp slurry was obtained. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed that the cellulose was a fine fibrous cellulose having a width of about 4 nm (see FIG. 3). Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 4)
A defibrated pulp slurry was obtained in the same manner as in Example 3 except that the hardwood kraft pulp was not dried and the treatment time with maleic anhydride was changed to 1 hour. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed that the cellulose was a fine fibrous cellulose having a width of about 4 nm (see FIG. 4). Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 5)
Defibering in the same manner as in Example 1 except that softwood kraft pulp (NBKP) was used instead of hardwood kraft pulp and the amount of maleic anhydride added was changed to 2 g (50 parts by weight with respect to 100 parts by weight of dry pulp). A pulp slurry was obtained.
When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 6)
A defibrated pulp slurry was obtained in the same manner as in Example 1 except that hemp pulp was used in place of hardwood kraft pulp and the amount of maleic anhydride added was changed to 2 g. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 7)
A defibrated pulp slurry was obtained in the same manner as in Example 1 except that 4 g of maleic anhydride was changed to 2 g of maleic anhydride (50 parts by mass with respect to 100 parts by mass of dry pulp). When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 8)
A defibrated pulp slurry was obtained in the same manner as in Example 1 except that 4 g of maleic anhydride was changed to 2 g of phthalic anhydride (50 parts by mass with respect to 100 parts by mass of dry pulp). When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained a cellulose I-type crystal, and addition of phthalic acid was confirmed by measurement of an infrared absorption spectrum by FT-IR.

Example 9
The hardwood kraft pulp was dried at 105 ° C. for 3 hours to obtain a dry pulp having a moisture content of 3% by mass or less. Next, 4 g of dried pulp and 2 g of maleic anhydride (50 parts by mass with respect to 100 parts by mass of dried pulp) were filled in an autoclave and treated at 150 ° C. for 2 hours.
Next, without washing with water, the dried pulp was dispersed in 250 mL of a 0.8 mass% aqueous sodium hydroxide solution, and the pulp was alkali-treated while stirring the slurry. The pH of the pulp slurry was about 12.5. Thereafter, the pulp after alkali treatment was washed with water until the pH became 8 or less.
Subsequently, ion-exchanged water was added to the pulp after the alkali treatment to prepare a slurry having a solid content concentration of 0.5% by mass. The slurry was defibrated for 30 minutes using a defibrating apparatus (Cleamix-2.2S, manufactured by MTechnic Co., Ltd.) at 21500 rpm, and finally a cooling / high-speed centrifuge (Kokusan Co., Ltd.). Manufactured by H-2000B) and centrifuged at 12000 G for 10 minutes, and the supernatant was recovered to obtain a defibrated pulp slurry.
When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Moreover, the cellulose maintained the cellulose I type crystal | crystallization by X-ray diffraction, and the crystallinity was 84%. Addition of maleic acid was confirmed by measurement of an infrared absorption spectrum by FT-IR.

(Example 10)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that 2 g of maleic anhydride was changed to 2 g of succinic anhydride (50 parts by mass with respect to 100 parts by mass of the dried pulp). When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose type I crystal, and addition of succinic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 11)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that 2 g of maleic anhydride was changed to 2 g of phthalic anhydride (50 parts by mass with respect to 100 parts by mass of dry pulp). When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained a cellulose I-type crystal, and addition of phthalic acid was confirmed by measurement of an infrared absorption spectrum by FT-IR.

Example 12
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that unbleached hardwood kraft pulp (LUKP, unbleached kraft pulp) was used. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 13)
A defibrated pulp slurry was obtained in the same manner as in Example 9, except that oxygen-bleached hardwood kraft pulp (LOKP, oxygen-bleached kraft pulp) was used. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 14)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that 12.5 mass% aqueous ammonia solution was used instead of 0.8 mass% sodium hydroxide. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 15)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that a 2.0 mass% tetramethylammonium hydroxide aqueous solution was used instead of 0.8 mass% sodium hydroxide. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 16)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that a 2.5 mass% tetraethylammonium hydroxide aqueous solution was used instead of 0.8 mass% sodium hydroxide. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 17)
A defibrated pulp slurry was obtained in the same manner as in Example 9 except that a 3.0% by mass tetrapropylammonium hydroxide aqueous solution was used instead of 0.8% by mass sodium hydroxide. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 18)
A defibrated pulp slurry was obtained in the same manner as in Example 9, except that a 3.5% by mass tetrabutylammonium hydroxide aqueous solution was used instead of 0.8% by mass sodium hydroxide. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 19)
A defibrated pulp slurry was obtained in the same manner as in Example 7 except that the reaction was performed at 130 ° C. for 2 hours in an autoclave. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 20)
The hardwood kraft pulp was dried at 105 ° C. for 3 hours to obtain a dry pulp having a water content of 3% or less. Next, a maleic anhydride solution obtained by dissolving 2 g of maleic anhydride in 4 g of acetone was added dropwise to 4 g of the dried pulp and stirred to soak the maleic anhydride solution in the dried pulp. Next, acetone was volatilized by drying at 40 ° C. for 30 minutes, and then the autoclave was filled. The autoclave was placed in an oven at 100 ° C. and treated for 2 hours. This introduced a carboxy group into the cellulose.
Next, the dried pulp treated with maleic anhydride was dispersed in 250 mL of 0.8% aqueous sodium hydroxide solution to form a slurry, and the resulting slurry was stirred to alkali-treat the pulp. The pH of the slurry was about 12.5. Thereafter, the pulp after alkali treatment was washed with water until the pH became 8 or less.
Next, ion-exchanged water was added to the pulp after washing with water to prepare a slurry having a solid content concentration of 0.5%. The slurry was defibrated for 30 minutes at 21500 rpm using a defibrating apparatus (Cleamix-2.2S, manufactured by M Technique Co., Ltd.). Then, the mixture was centrifuged at 12000 G for 10 minutes using a cooling high-speed centrifuge (manufactured by Kokusan Co., Ltd., H-2000B), and the supernatant was collected to obtain a fine fibrous cellulose dispersion.
When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Example 21)
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 20 except that 0.8% calcium hydroxide was used instead of 0.8% sodium hydroxide in the alkali washing step. The pH of the slurry during alkali washing was about 12.8. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Further, by X-ray diffraction, the cellulose maintained the cellulose I type crystal, and addition of maleic acid was confirmed by measurement of infrared absorption spectrum by FT-IR.

(Comparative Example 1)
The alkali treatment in Example 3 was omitted, and an attempt was made to defibrate the slurry after the maleic anhydride treatment. However, since the slurry contained many lumps of pulp, it could not be defibrated.

(Comparative Example 2)
The treatment with the maleic anhydride of the dried pulp was omitted, and a defibrated pulp slurry was obtained in the same manner as in Example 3 except that the dried pulp was alkali-treated and then defibrated. When the cellulose contained in the defibrated pulp slurry was observed with a transmission electron microscope, it was confirmed to be a fine fibrous cellulose having a width of about 4 nm. Moreover, it was confirmed by X-ray diffraction that the cellulose maintained the cellulose I type crystal.

(Comparative Example 3)
A defibrated pulp slurry was obtained in the same manner as in Example 3 except that maleic anhydride treatment and alkali treatment were omitted.

(Comparative Example 4)
A defibrated pulp slurry was obtained in the same manner as in Example 12 except that maleic anhydride treatment and alkali treatment were omitted.

(Comparative Example 5)
The pulp was not dried, and a defibrated pulp slurry was obtained in the same manner as in Example 3 except that maleic anhydride treatment and alkali treatment were omitted.

(Evaluation)
For the defibrated pulp slurries of Examples 1 to 21 and Comparative Examples 2 to 5, the supernatant yield after centrifugation was measured by the method described below. The measurement results are shown in Table 1. The supernatant yield after centrifugation is an indicator of the yield of fine fibrous cellulose, and the higher the supernatant yield, the higher the yield of fine fibrous cellulose. About Comparative Example 1, since there were many block-shaped grains and defibration processing could not be performed, the supernatant yield could not be measured.

[Measurement of supernatant yield after centrifugation]
Add deionized water to the defibrated pulp slurry to adjust the slurry solids concentration to 0.2% by mass, and centrifuge at 12000G for 10 minutes using a cooled high-speed centrifuge (Kokusan, H-2000B). Then, the obtained supernatant was collected, and the solid content concentration of the supernatant was measured.
After the measurement, the yield of the supernatant was obtained from the formula of the solid content concentration of the supernatant / 0.2% by mass.
The supernatant yield after centrifugation is the yield of fine fibrous cellulose obtained by excluding the aggregates of fine fibrous cellulose and non-fine fibrous materials having a large fiber width, and the supernatant yield is high. The yield of finer fine fibrous cellulose is higher.

[Transmission electron microscope observation]
The supernatant was diluted with water and dropped onto a carbon grid membrane that had been subjected to a hydrophilic treatment. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (JEOL JEM-2000EX, manufactured by JEOL Ltd.).

In Examples 1 to 21, in which the fiber raw material was treated with an anhydride of dicarboxylic acid and then subjected to alkali treatment, the supernatant yield after centrifugation was high and the yield of fine fibrous cellulose was high.
In Comparative Example 2 in which the treatment with the dicarboxylic acid anhydride was omitted, the supernatant yield after centrifugation was low, and the yield of fine fibrous cellulose was low.
Further, in comparison with Examples 1 to 3 and Example 4, in Examples 1 to 3 in which the pulp was dried, the fiber length of the obtained fine fibrous cellulose was obtained in Example 4 in which the pulp was not dried. It was longer than fine fibers. Since the fiber width of the fine fibrous cellulose in Examples 1 to 4 is the same, the axial ratio of the fine fibrous cellulose obtained in Examples 1 to 3 is larger than that of the fine fibrous cellulose obtained in Example 4. (See Figures 1-4).
In Examples 12 and 13 using unbleached kraft pulp, the supernatant yield after centrifugation was higher than that in Comparative Example 4, and the yield of fine fibrous cellulose was high. Example 20 in which maleic anhydride was dissolved in advance with acetone and uniformly impregnated into the pulp had a higher supernatant yield after centrifugation than Example 9.

(Example 22)
<Manufacture of non-woven fabric>
The slurry containing fine fibrous cellulose obtained in Example 8 was diluted with water so that the cellulose concentration became 0.127% by mass, adjusted to 150 ml, and 30 ml of isopropyl alcohol was gently added from above the liquid, and the pressure was reduced. Filtration was performed. As a filter, KG-90 made by Advantech was used, and a PTFE membrane filter made by Advantech having a pore size of 1.0 μm was placed on the glass filter. The effective filtration area was 48 cm ² . Filtration under reduced pressure at a reduced pressure of -0.09 MPa (absolute vacuum of 10 kPa) yielded a cellulose fiber deposit on the PTFE membrane filter. This cellulose deposit was press-dried at a pressure of 0.15 MPa for 5 minutes with a press machine heated to 120 ° C. to obtain a porous nonwoven fabric.

(Example 23)
<Manufacture of acetylated nonwoven fabric>
The cellulose to which phthalic acid was added by the method of Example 8 was acetylated in acetic anhydride at 115 ° C. for 5 hours. Thereafter, it was thoroughly washed with distilled water and defibrated in the same manner as in Example 1 to obtain a fine fibrous cellulose-containing slurry. Using this fine fibrous cellulose-containing slurry, a nonwoven fabric was formed in the same manner as in Example 22 to obtain an acetylated nonwoven fabric.

(Evaluation)
About the nonwoven fabric of the said Examples 22 and 23, the chemical modification rate and the porosity of the cellulose were measured by the method as described below. The measurement results are shown in Table 2.

[Chemical modification rate of cellulose]
The chemical modification rate was determined by the method described above.

[Porosity of nonwoven fabric]
It calculated | required by the following formula from the area, thickness, and mass of the nonwoven fabric.
Porosity (vol%) = {1-B / (M × A × t)} × 100
Here, A is the area (cm ² ) of the nonwoven fabric, t (cm) is the thickness, B is the mass (g) of the nonwoven fabric, M is the density of cellulose, and M = 1.5 g / cm ³ is assumed in the present invention. did. The film thickness of the nonwoven fabric was measured at 10 points for various positions of the nonwoven fabric using a film thickness meter (IP65 manufactured by Mitutoyo Co., Ltd.), and the average value was adopted.

The nonwoven fabrics of Examples 22 and 23 both had an appropriate porosity.

(Example 24)
<Composite with resin matrix material>
The acetylated cellulose nonwoven fabric obtained in Example 23 was mixed with 80 parts by mass of 1,10-decandiol dimethacrylate, 20 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate), 2,4,6-trimethylbenzoyldiphenylphosphine. A solution prepared by mixing 0.02 parts by mass of oxide ("Lucirin TPO" manufactured by BASF) and 0.02 parts by mass of Irganox 184 was impregnated and left overnight under reduced pressure. The obtained cellulose fiber aggregate impregnated with the resin solution was sandwiched between two glass plates, and was cured with an ultraviolet ray using an electrodeless mercury lamp lamp (“D bulb” manufactured by Fusion UV Systems). Conditions of UV curing, irradiation intensity 400 mW / cm ² at a wavelength 365 nm, is semi-cured through the front and back ten times the line speed of 7m / min, then the irradiation intensity at a wavelength of 365nm 1900mW / cm ^2, line speed 2m / The test was carried out under conditions of complete curing by passing 10 times each on the front and back sides (total 20 times).
After the ultraviolet irradiation, the glass plate was removed and heated at 190 ° C. under an oxygen partial pressure of 0.006 MPa or less for 1 hour to obtain a cellulose fiber composite having a thickness of 75 μm. The resulting composite had a tensile modulus of elasticity at 23 ° C. of 7.0 Pa.
The ultraviolet irradiance was measured with an ultraviolet illuminance meter “UV-M02” manufactured by Oak Seisakusho using an attachment “UV-35”, and the illuminance of ultraviolet rays of 320 to 390 nm was measured at 23 ° C.

(Example 25)
(Epoxy emulsion papermaking)
50 parts by mass of the fine fibrous cellulose-containing slurry obtained in Example 9 diluted to a solid content concentration of 0.2% by mass and an epoxy resin emulsion W2821R70 diluted to a solid content concentration of 0.2% by mass (manufactured by Japan Epoxy Resin Co., Ltd.) ) After mixing 50 parts by mass of slurry and 5 parts by mass of imidazole-based curing agent EMI24 (manufactured by Japan Epoxy Resin Co., Ltd.) diluted to a solids concentration of 0.2% by mass, the slurry has a solids concentration of 0.2% by mass. 1 part by mass of a coagulant (FS-614, Kurita Kogyo) aqueous solution was added and stirred for 1 minute. The obtained mixed liquid was sucked and dehydrated on a polytetrafluoroethylene membrane filter having a pore diameter of 0.5 μm so as to have a basis weight of 50 g / m ² to obtain a deposit. The deposit was dried with a cylinder dryer at 120 ° C. to obtain a fine fibrous cellulose-matrix composite.
Four obtained composites were stacked and then pressed for 1 hour at a pressure of 10 kgf / cm ² using a press machine heated to 170 ° C. The composite after pressing had a thickness of 150 μm. The resulting composite had a tensile elastic modulus at 23 ° C. of 6.2 GPa.

[Tensile modulus of composite]
The obtained composite was cut into a length of 10 mm × 40 mm with a laser cutter. Using a DMS6100 manufactured by SII, the chuck was 20 mm in chuck mode, the frequency was 10 Hz, and 2 ° C./min. The tensile elastic modulus was determined from the storage elastic modulus E ′ (unit: GPa) at 23 ° C. from −100 ° C. to 250 ° C.

[Yellowness of complex]
The obtained composite was heated at 190 ° C. at an oxygen partial pressure of 0.006 MPa or less for 1 hour, and then yellowness was measured using a color computer manufactured by Suga Test Instruments in accordance with JIS standard K7105.

[Total light transmittance of composite]
Based on JIS standard K7105, the total light transmittance by C light was measured using the haze meter by Suga Test Instruments.

[Linear thermal expansion coefficient of composite]
The obtained composite was cut into 3 mm width × 30 mm length with a laser cutter. This was pulled at 5 ° C./min. From room temperature to 180 ° C. in a pulling mode using TMA120 manufactured by SII in a pulling mode with a chuck distance of 20 mm, a load of 10 g, and a nitrogen atmosphere. At 180 ° C. to 25 ° C. at 5 ° C./min. At 25 ° C to 180 ° C, 5 ° C / min. The linear thermal expansion coefficient was determined from the measured value from 60 ° C. to 100 ° C. at the time of the second temperature increase.

The composite of Example 24 had a low yellowness with a high elastic modulus and a low linear thermal expansion coefficient. The composite of Example 25 had a high elastic modulus and a low linear thermal expansion coefficient.

According to the method for producing fine fibrous cellulose of the present invention, the fiber raw material can be sufficiently refined, and the yield of fine fibrous cellulose is high, so that the production efficiency of fine fibrous cellulose from the fiber raw material is high. Moreover, the manufacturing method of the fine fibrous cellulose of this invention is low cost, and its environmental impact is small. Moreover, according to the manufacturing method of the nonwoven fabric of this invention, the manufacturing efficiency of the nonwoven fabric with respect to a fiber raw material can be improved. Furthermore, since the fine fibrous cellulose of the present invention has a small fiber width and a large axial ratio (fiber length / fiber width), the slurry stability of the fine fibrous cellulose is high, and the resulting nonwoven fabric has high strength. Moreover, since the composite of the fine fibrous cellulose and the matrix resin of the present invention has high strength and a low coefficient of linear thermal expansion, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 3a Slurry containing fine fibrous cellulose 3b Hydrous web 3c Non-woven fabric 10 Paper making wire 20 Dehydration section 40 Drying section 60 Winding section

Claims

A fiber raw material containing cellulose is obtained by at least one carboxylic acid compound selected from the group consisting of a compound having two or more carboxy groups, an acid anhydride of a compound having two or more carboxy groups, and derivatives thereof. A carboxy group introduction step of treating and introducing a carboxy group into cellulose;
After the completion of the carboxy group introduction step, an alkali treatment step of treating the cellulose introduced with the carboxy group with an alkaline solution;
A method for producing fine fibrous cellulose, comprising a defibrating treatment step of defibrating cellulose after the alkali treatment.
The method for producing fine fibrous cellulose according to claim 1, wherein the carboxy group introduction step is a step of adding the carboxylic acid compound to a hydroxy group of cellulose.
3. The compound according to claim 1, wherein the carboxylic acid compound is a compound selected from the group consisting of maleic acid, succinic acid, phthalic acid, maleic acid, succinic acid, acid anhydrides of phthalic acid, and derivatives thereof. Of producing fine fibrous cellulose.
The method for producing fine fibrous cellulose according to any one of claims 1 to 3, wherein the carboxylic acid compound is an acid anhydride.
The method for producing fine fibrous cellulose according to any one of claims 1 to 4, wherein the carboxy group introduction step is a step of treating cellulose with the gasified carboxylic acid compound.
The method for producing fine fibrous cellulose according to any one of claims 1 to 5, further comprising preliminarily setting the moisture of the fiber raw material to 10% by mass or less based on the absolute dry weight of the fiber raw material.
A dehydration step of dehydrating a slurry containing fine fibrous cellulose produced by the method for producing fine fibrous cellulose according to any one of claims 1 to 6 on a filter medium to obtain a wet paper, and drying the wet paper The manufacturing method of the nonwoven fabric which has a drying process to make.
A fine fibrous cellulose having a fiber width of 1 to 1000 nm, wherein some of the hydroxy groups of cellulose constituting the fibers are hydroxy groups substituted with a functional group represented by the following structural formula (1).

(In the structural formula (1), R represents a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched group. Any of a chain hydrocarbon group, an aromatic group, and a single bond, and M is a cationic group.)
A fine fibrous cellulose-containing slurry obtained by dispersing the fine fibrous cellulose according to claim 8 in a dispersion medium.
A nonwoven fabric containing the fine fibrous cellulose according to claim 8.
A composite containing the fine fibrous cellulose according to claim 8 and a matrix material.
A composite containing the nonwoven fabric according to claim 10 and a matrix material.