WO2013058244A1

WO2013058244A1 - Method for production of chemically modified cellulose non-woven fabric and chemically modified cellulose non-woven fabric, and cellulose fiber resin composite material produced using said chemically modified cellulose non-woven fabric and method for production thereof

Info

Publication number: WO2013058244A1
Application number: PCT/JP2012/076725
Authority: WO
Inventors: 幸子澤田; 尚秀荻田
Original assignee: 三菱化学株式会社
Priority date: 2011-10-17
Filing date: 2012-10-16
Publication date: 2013-04-25
Also published as: JPWO2013058244A1

Abstract

The purpose of the present invention is to provide a method for producing a chemically modified cellulose non-woven fabric which does not undergo the problem of discoloration or deterioration in strength when prepared into a composite material with high productivity by performing the chemical modification of cellulose in an industrially advantageous manner. The present invention is a method for producing a chemically modified cellulose non-woven fabric, comprising chemically modifying cellulose in a cellulose non-woven fabric using a reactive gas. The production method enables the reduction in reaction time, and also enables the high-productivity production of a chemically modified cellulose non-woven fabric without requiring the use of any extra chemical substance such as a catalyst, a solvent and a diluting agent.

Description

Method for producing chemically modified cellulose nonwoven fabric, chemically modified cellulose nonwoven fabric, cellulose fiber resin composite material using the same, and method for producing the same

The present invention relates to a method for producing a chemically modified cellulose nonwoven fabric and a cellulose fiber composite material using the chemically modified cellulose nonwoven fabric. More specifically, the present invention relates to a cellulose fiber nonwoven fabric having a number average fiber diameter of 2 to 400 nm. The present invention also relates to a technique for chemically modifying cellulose of this cellulose nonwoven fabric in a gas phase by bringing a reactive gas into contact therewith. Further, the present invention relates to a technique for realizing high strength, high transparency, non-coloring property, and low linear expansion coefficient when a cellulose fiber composite material is formed using the chemically modified cellulose nonwoven fabric.

In recent years, composite materials using fine cellulose fibers such as bacterial cellulose have been actively studied. Since cellulose has an extended chain crystal, it is known to exhibit a low linear expansion coefficient, a high elastic modulus, and a high strength. Finer and finer cellulose nanofibers with a thickness in the range of several nm to 200 nm are obtained by miniaturization, and high transparency and low linear expansion are achieved by filling the gaps between the fibers with a matrix material. It has been reported that composite materials having a rate can be obtained.

However, while cellulose has such excellent characteristics, it has the disadvantages that the degree of polymerization is lowered by heating, coloration and dimensional change associated with it occur, and water resistance and moisture resistance are inferior to other materials. In order to make up for the drawbacks of cellulose, attempts have been made to modify or modify cellulose.

For example, Patent Document 1 discloses a method of chemically modifying cellulose by immersing a cellulose non-woven fabric in an acetic acid / acetic anhydride solution and causing an acetylation reaction at room temperature. However, when the cellulose nonwoven fabric is chemically modified by this method, the reaction rate of the chemical modification is very low, and there is a problem that the composite material obtained using this nonwoven fabric is colored when heated.

Further, in Patent Document 2, a cellulose nonwoven fabric is immersed in an acetic anhydride solution and subjected to acetylation reaction at 110 ° C. for 7 hours to obtain a cellulose nonwoven fabric having a desired chemical modification rate. Realizes high transparency and non-coloring. However, this method has a problem that, when chemically modifying, a large amount of drug is required to immerse the cellulose nonwoven fabric, and a process of removing and washing excess drug after the reaction is required. In addition, since the reaction time is long, the degree of polymerization of cellulose is reduced during the reaction, and the strength is lowered when a composite material is formed.

Japanese Unexamined Patent Publication No. 2007-51266 Japanese Unexamined Patent Publication No. 2009-161896

Conventional cellulose non-woven fabric chemical modification methods have long reaction times, require a large amount of chemicals, have complicated processes, etc., and have poor productivity and are difficult to implement on a commercial scale. In addition, there are problems that the cellulose fiber composite material produced using the obtained cellulose nonwoven fabric is colored when heated, and that the strength of the composite material is reduced due to a decrease in the degree of polymerization of cellulose. It was.

In view of the above-described conventional situation, the present invention performs a chemical modification of cellulose by an industrially advantageous method to produce a chemically modified cellulose nonwoven fabric having no problem of coloring or strength reduction when used as a composite material with high productivity. It is an object to provide a manufacturing method.
Furthermore, this invention makes it a subject to provide the cellulose fiber composite material of high intensity | strength, high transparency, a non-coloring property, and a low linear expansion coefficient using the chemically modified cellulose nonwoven fabric obtained by this manufacturing method.

As a result of intensive studies on the above problems, the inventors of the present invention can shorten the reaction time by chemically modifying the cellulose of the cellulose nonwoven fabric in the gas phase using a reactive gas. It has been found that a chemically modified cellulose non-woven fabric can be produced with good productivity without using an extra drug such as a diluent, and further a decrease in the degree of polymerization of cellulose can be suppressed.

That is, the gist of the present invention is a method for producing a chemically modified cellulose nonwoven fabric characterized by chemically modifying cellulose in the cellulose nonwoven fabric using a reactive gas, and a chemically modified cellulose nonwoven fabric produced by the production method. It exists in the cellulose fiber resin composite material containing matrix materials, such as resin.

The present invention is characterized by the following (1) to (9).
(1) A method for producing a chemically modified cellulose nonwoven fabric,
Using a cellulose nonwoven fabric of cellulose fibers having a number average fiber diameter of 2 to 400 nm,
The manufacturing method of chemically modifying the cellulose in the said cellulose nonwoven fabric using reactive gas.
(2) The said reactive gas is a manufacturing method of the cellulose nonwoven fabric as described in said (1) which is an acid or acid anhydride of a gaseous state.
(3) The manufacturing method of the chemically modified cellulose nonwoven fabric as described in said (1) or (2) which makes the said reactive gas contact with a roll-shaped cellulose nonwoven fabric.
(4) Production of chemically modified cellulose nonwoven fabric according to any one of (1) to (3) above, wherein the temperature in the reaction system when chemically modified using the reactive gas is 250 ° C. or lower Method.
(5) The method for producing a chemically modified cellulose nonwoven fabric according to any one of (1) to (4) above, wherein the reaction time when chemically modifying using the reactive gas is 3 hours or less.
(6) The method for producing a chemically modified cellulose nonwoven fabric according to any one of (1) to (5) above, wherein the chemically modified cellulose nonwoven fabric obtained has a chemical modification rate of 5 to 65 mol%.
(7) A chemically modified cellulose nonwoven fabric produced by the production method according to any one of (1) to (6) above.
(8) A cellulose fiber resin composite material containing the chemically modified cellulose nonwoven fabric and resin according to (7) above.
(9) After chemically modifying cellulose in a cellulose nonwoven fabric of cellulose fibers having a number average fiber diameter of 2 to 400 nm using a reactive gas,
A method for producing a cellulose fiber resin composite material, wherein a chemically modified cellulose nonwoven fabric and a resin are combined.

According to the present invention, in chemical modification of cellulose nonwoven fabric, the reaction time can be shortened as compared with the conventional method, the amount of extra chemicals can be reduced, and the process such as the washing step can be simplified. A chemically modified cellulose nonwoven fabric can be produced with good productivity. Moreover, since reaction time can be shortened, the fall of the polymerization degree of the cellulose during chemical modification reaction can be suppressed, and the strength reduction at the time of using a composite material can be suppressed. Furthermore, since the reaction is performed in the gas phase, the diffusion of the reaction solvent is faster than the reaction in the liquid phase, the uniformity of the reaction is improved, and a more uniform chemically modified cellulose nonwoven fabric can be provided. .

Thus, according to the present invention, not only the process is simplified by contacting with the reactive gas, but also the reaction time is shortened by improving the reaction efficiency, and the polymerization time of cellulose is reduced by shortening the reaction time. Decrease in strength and resulting reduction in strength can be suppressed, and a chemically modified cellulose nonwoven fabric that is uniformly chemically modified can be provided. Using this chemically modified cellulose nonwoven fabric, high strength, high transparency, non-coloring property, low line A cellulose fiber composite material having an expansion coefficient can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of a denaturing apparatus that can be used for chemical modification of a cellulose nonwoven fabric in the method for producing a chemically modified cellulose nonwoven fabric of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of a denaturing apparatus that can be used for chemical modification of a cellulose nonwoven fabric in the method for producing a chemically modified cellulose nonwoven fabric of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of a denaturing apparatus that can be used for chemical modification of a cellulose nonwoven fabric in the method for producing a chemically modified cellulose nonwoven fabric of the present invention. 4 is a cross-sectional view of a block-like cellulose nonwoven fabric produced in Example 8. FIG. FIG. 5 is a cross-sectional view of a cellulose nonwoven fabric wound in a roll shape.

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Method for producing cellulose nonwoven fabric]
The method for producing a chemically modified cellulose nonwoven fabric of the present invention is characterized by chemically modifying cellulose in the cellulose nonwoven fabric using a reactive gas.

[Cellulose nonwoven fabric]
First, the cellulose nonwoven fabric which performs chemical modification in this invention is demonstrated.

The cellulose nonwoven fabric in the present invention is a sheet of fine cellulose fibers, and is usually produced by filtering or applying a dispersion containing cellulose fibers to a suitable substrate. It is a shape.

{Cellulose fiber}
Initially, the cellulose fiber used for a cellulose nonwoven fabric is demonstrated.
Cellulose fibers may be any of cellulose-containing materials, cellulose fiber materials purified from cellulose-containing materials, and fine cellulose fibers defibrated from cellulose fiber materials as long as the number average fiber diameter is 2 to 400 nm. . In order to apply to the use described in detail below, it is preferable to use fine cellulose fibers for the cellulose nonwoven fabric.

As the cellulose fiber, only cellulose itself may be used or cellulose partially containing impurities may be used.

<Cellulose-containing material>
Examples of cellulose-containing materials include woods such as conifers and hardwoods (wood flour, etc.), cotton such as cotton linter and cotton lint, pomace such as sugar cane and sugar radish, bast fibers such as flax, ramie, jute, kenaf, etc. Vegetal vein fibers such as sisal and pineapple, petiole fibers such as abaca and banana, fruit fibers such as coconut palm, stem stem fibers such as bamboo, bacterial cellulose produced by bacteria, seaweed and squirts such as valonia and falcon Natural cellulose such as encapsulates. These natural celluloses are preferable because of their high crystallinity and low linear expansion and high elastic modulus. In particular, cellulose fibers obtained from plant-derived materials are preferred.

Bacterial cellulose is preferred in that it can be easily obtained with a fine fiber diameter. Cotton is also preferable in that it is easy to obtain a fine fiber diameter, and more preferable in terms of easy acquisition of raw materials.
In addition, wood of conifers and hardwoods with fine fiber diameters can be obtained, and it is the largest amount of biological resources on the planet. It is a sustainable resource that produces about 70 billion tons per year. Therefore, it contributes greatly to the reduction of carbon dioxide that affects global warming, which is advantageous from an economic point of view. When wood is used as the cellulose fiber of the present invention, it is preferably used after being crushed into a state of wood chips or wood flour.

<Cellulose fiber raw material>
The cellulose fiber raw material is obtained by purifying the cellulose-containing material by a usual method.
For example, it can be obtained by degreasing the above cellulose-containing material with benzene-ethanol or an aqueous sodium carbonate solution, then subjecting it to delignification treatment with chlorite (Wise method) and subjecting it to dehemicellulose treatment with alkali. In addition to the Wise method, a method using peracetic acid (pa method), a method using a peracetic acid persulfuric acid mixture (pxa method), and the like are also used as purification methods. Moreover, you may perform a bleaching process etc. further suitably. This crushing may be performed at any timing before, after or after the purification treatment described later.

As a dispersion medium used for the purification treatment, water is generally used, but an aqueous solution of an acid or base or other treatment agent may be used, and in this case, it may be finally washed with water. .

The degree of purification of the cellulose fiber raw material obtained by refining the cellulose-containing material is not particularly defined, but it is preferable that the fat content of the cellulose fiber raw material is less because the fat and oil and lignin are less and the cellulose component content is higher. The cellulose fiber raw material may be obtained by a general method for producing chemical pulp, for example, a method for producing kraft pulp, salified pulp, alkali pulp, or nitrate pulp.
That is, as a cellulose fiber raw material, you may use hardwood kraft pulp, softwood kraft pulp, hardwood sulfite pulp, softwood sulfite pulp, hardwood bleached kraft pulp, softwood bleached kraft pulp, linter pulp and the like.

The content of the cellulose component in the cellulose fiber raw material is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more.

The cellulose component of the cellulose fiber raw material can be classified into a crystalline α-cellulose component and an amorphous hemicellulose component. It is preferable that the content of crystalline α-cellulose is large because the effects of low linear expansion coefficient, high elastic modulus, and high strength are easily obtained when a cellulose fiber composite material is obtained. Therefore, the α-cellulose content of the cellulose fiber raw material is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 97% by weight or more.

The fiber diameter of the cellulose fiber raw material is not particularly limited, but is usually 1 μm to 1 mm as the number average fiber diameter.
In addition, the number average fiber diameter of the cellulose fiber raw material which passed through general refinement | purification is about 50 micrometers normally.

<Fine cellulose fiber>
The fine cellulose fiber is usually obtained by defibrating a cellulose fiber raw material, and its number average fiber diameter is preferably 400 nm or less, more preferably 150 nm or less, and 100 nm or less. Is more preferably 80 nm or less, most preferably 50 nm or less, and further preferably 30 nm or less. The number average fiber diameter of the fine cellulose fibers is preferably as small as possible. However, in order to develop a low linear expansion coefficient and a high elastic modulus, it is important to maintain the crystallinity of cellulose. Is 4 nm or more which is the fiber diameter of the cellulose crystal unit.

In addition, the fiber diameter of the fine cellulose fiber can be determined by measuring the cellulose nonwoven fabric obtained by drying and removing the dispersion medium in the fine cellulose fiber dispersion described in detail below by observing with SEM, TEM or the like. . Specifically, it is usually observed with SEM, TEM, etc., a line is drawn on the diagonal line of the photograph, 12 points of fibers in the vicinity are randomly extracted, and 10 points obtained by removing the thickest fiber and the thinnest fiber are extracted. The number average fiber diameter is measured and averaged.

The cellulose fiber raw material is normally defibrated in a cellulose fiber raw material dispersion (cellulose fiber raw material dispersion). In the dispersion, the solid content concentration as the cellulose fiber raw material is 0.1% by weight or more, preferably 0.2% by weight or more, particularly 0.3% by weight or more, and 10% by weight or less, particularly 6% by weight or less. The cellulose fiber raw material dispersion is preferably used. If the solid content concentration in the cellulose fiber raw material dispersion used in this defibrating process is too low, the amount of liquid will increase with respect to the amount of cellulose to be treated, resulting in poor efficiency, and if the solid content concentration is too high, the fluidity will be poor. The concentration of the cellulose fiber raw material dispersion to be subjected to the defibration treatment is preferably adjusted by adding water as appropriate.

As the dispersion medium, an organic solvent, water, or a mixed solution of an organic solvent and water can be used. Organic solvents include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, n-butanol, ethylene glycol, ethylene glycol mono-t-butyl ether and other alcohols, acetone and methyl ethyl ketone ketones, and other water-soluble organics. One kind or two or more kinds of solvents can be used. The dispersion medium is preferably a mixed liquid of an organic solvent and water or water, and particularly preferably water.

There are no particular restrictions on the method of defibrating the cellulose fiber raw material, but for example, ceramic beads having a diameter of about 1 mm are placed in the cellulose fiber raw material dispersion, and vibration is applied using a paint shaker or bead mill. Cellulosic fiber raw material is defibrated, blended with a blender-type disperser or a high-speed rotating slit, using a cellulose fiber raw material dispersion to apply shearing force (high-speed rotating homogenizer method), By depressurizing the cellulose fiber to generate shear force between cellulose fibers (high pressure homogenizer method), a method using a counter collision type disperser (Masuko Sangyo) such as “Masscomizer X”, etc. Can be mentioned. In particular, the high-speed rotating homogenizer and the high-pressure homogenizer treatment improve the efficiency of defibration.

In addition, you may perform the refinement | miniaturization process which combined the ultrasonic process after the above processes.

In this case, the frequency of the ultrasonic wave is 15 kHz to 1 MHz, preferably 20 kHz to 500 kHz, more preferably 20 kHz to 100 kHz. If the frequency of the ultrasonic wave to be irradiated is too small, cavitation described later is difficult to occur, and if it is too large, the generated cavitation disappears without growing until it causes a physical action. I can't. Moreover, as an output of an ultrasonic wave, it is 1 W / cm < ² > or more as an execution output density, Preferably it is 10 W / cm < ² > or more, More preferably, it is 20 W / cm < ² > or more. If the output of the ultrasonic wave is too small, the miniaturization efficiency is lowered, and a long time irradiation is necessary for sufficient miniaturization, which is not practical. In addition, the upper limit of the effective output density of the ultrasonic wave is 500 W / cm ² or less from the viewpoint of durability of the vibrator and the horn.

The ultrasonic irradiation method is not particularly limited, and various methods can be used. For example, by directly inserting a horn that transmits the vibration of an ultrasonic vibrator into the cellulose fiber raw material dispersion, a method for directly refining cellulose fibers, or a floor or wall of a container containing a cellulose fiber raw material dispersion. Place ultrasonic transducers on the part to make cellulose fibers fine, or put a liquid such as water in a vessel equipped with ultrasonic transducers, and immerse the vessel containing the cellulose fiber raw material dispersion in it. Thus, a method of applying ultrasonic vibration indirectly to the cellulose fiber raw material dispersion liquid through a liquid such as water can be employed.

Further, the ultrasonic wave may be irradiated continuously or intermittently at a predetermined interval.

In addition, after the defibrating treatment, it is preferable to separate and remove the defibrated cellulose fibers in the fine cellulose fiber dispersion using centrifugation. By centrifuging, a supernatant of a more uniform and fine fine cellulose fiber dispersion can be obtained. The conditions for the centrifugation are not particularly limited because they depend on the miniaturization process used, but it is preferable to apply a centrifugal force of, for example, 3000 G or more, preferably 10,000 G or more. The time is preferably 1 minute or longer, preferably 5 minutes or longer. If the centrifugal force is too small or the time is too short, separation / removal of poorly defibrated cellulose fibers becomes insufficient, which is not preferable.

Further, when the centrifugal separation is performed, it is not preferable that the fine cellulose fiber dispersion has a high viscosity because the separation efficiency is lowered. As the viscosity of the fine cellulose fiber dispersion, the viscosity at a shear rate of 10 s ⁻¹ measured at 25 ° C. is 500 mPa · s or less, preferably 100 mPa · s or less.

{Method for producing cellulose nonwoven fabric}
A cellulose nonwoven fabric is normally manufactured using the fine cellulose fiber obtained as mentioned above. A cellulose non-woven fabric can be produced with a high transparency, a low linear expansion coefficient, and a high elastic modulus when it is produced using fine cellulose fibers rather than using a cellulose fiber raw material before defibration. Specifically, the cellulose nonwoven fabric is obtained by filtering a dispersion containing fine cellulose fibers (fine cellulose fiber dispersion) obtained by performing the above-described defibrating treatment, or by applying to a suitable substrate. Manufactured as a sheet.

When a cellulose nonwoven fabric is produced by filtering a fine cellulose fiber dispersion, the fine cellulose fiber concentration of the dispersion subjected to filtration is usually 0.01% by weight or more, preferably 0.05% by weight or more. Preferably it is 0.1 weight% or more. If the concentration of the fine cellulose fibers is too low, it takes a long time for filtration, which is not preferable. The concentration of fine cellulose fibers is usually 10% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less, still more preferably 1.5% by weight or less, and particularly preferably 1.2% by weight or less. Preferably it is 1.0 weight% or less. If the concentration of fine cellulose fibers is too high, a uniform sheet cannot be obtained, which is not preferable.

When filtering the fine cellulose fiber dispersion, it is important that the fine cellulose fibers do not pass through and the filtration speed is not too slow as a filter cloth at the time of filtration. As such a filter cloth, a sheet made of an organic polymer, a woven fabric, and a porous membrane are preferable. The organic polymer is preferably a non-cellulose organic polymer such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) or the like. More specifically, a porous film of polytetrafluoroethylene having a pore diameter of 0.1 to 20 μm, for example, 1 μm, polyethylene terephthalate or polyethylene fabric having a pore diameter of 0.1 to 20 μm, for example, 1 μm, and the like can be mentioned. Moreover, the paper base material which consists of cellulose which is a natural fiber can be used as a filter medium. The paper substrate is very preferable because it can easily produce a wide or long paper material, and can control the amount of water passing through the paper by changing the type of pulp as the raw material or the beating degree of the pulp. It is also possible to easily impart water resistance to the base with a water-proofing agent or a hydrophobizing agent.

The cellulose nonwoven fabric obtained by the filtration is then dried, but in some cases, it may proceed to the next step without drying.
That is, for example, when the heat-treated fine cellulose fiber dispersion is filtered, it can be directly used for the next step without passing through the drying step.
Moreover, also when filtering the fine cellulose fiber dispersion liquid and heat-processing the obtained cellulose nonwoven fabric, it can also carry out without passing through a drying process.
However, it is preferable to perform drying also in the sense of controlling the porosity, film thickness, and strengthening the structure of the nonwoven fabric. This drying may be air drying, vacuum drying, pressure drying, or freeze drying.
Moreover, you may heat-dry. When heating, 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. If the heating temperature is too low, drying may take time or drying may be insufficient, and if the heating temperature is too high, the cellulose nonwoven fabric may be colored or cellulose may be decomposed. Moreover, when pressurizing, 0.01 MPa or more is preferable, 0.1 MPa or more is more preferable, 5 MPa or less is preferable, and 1 MPa or less is more preferable. If the pressure is too low, drying may be insufficient, and if the pressure is too high, the cellulose nonwoven fabric may be crushed or cellulose may be decomposed.
Moreover, you may manufacture a cellulose nonwoven fabric as a sheet-like material by apply | coating a fine cellulose fiber dispersion liquid to a suitable base material. In this case, usually, the dispersion is applied onto a predetermined substrate, and the dispersion medium is evaporated to a specific amount and removed. The coating method is not particularly limited, and examples thereof include spin coating, blade coating, wire bar coating, spray coating, and slit coating. In particular, the spin coating method is preferable in that a thin film having a uniform thickness can be obtained.
In addition, it does not specifically limit as a board | substrate, A glass substrate, a plastic substrate, etc. are mentioned.

{Physical properties of cellulose nonwoven fabric}
<Porosity>
The cellulose nonwoven fabric can have various porosity depending on the production method.

When a cellulose nonwoven fabric is impregnated with a resin to obtain a cellulose fiber composite material, it is preferable that the cellulose nonwoven fabric has a certain degree of porosity because the resin is difficult to be impregnated if the porosity of the cellulose nonwoven fabric is small. The porosity in this case is usually 10% by volume or more, preferably 20% by volume or more. However, when the porosity is excessively large, the coefficient of linear expansion increases when the cellulose fiber composite material is obtained, and therefore, the porosity of the cellulose nonwoven fabric is preferably 60% by volume or less.

The porosity of a cellulose nonwoven fabric here can be calculated | required easily by a following formula.
Porosity (volume%) = {(1−B / (M × A × t)} × 100
Here, A is the area (cm ² ) of the cellulose nonwoven fabric, t is the thickness (cm), B is the weight (g) of the cellulose nonwoven fabric, M is the density of cellulose, and in the present invention, M = 1.5 g / cm ³ Assume that The film thickness of the cellulose nonwoven fabric is measured at 10 points at various positions of the cellulose nonwoven fabric using a film thickness meter (PDN-20 manufactured by PEACOK), and the average value is adopted.

Examples of a method for obtaining a cellulose nonwoven fabric having a large porosity include a method in which water in the cellulose nonwoven fabric is finally replaced with an organic solvent such as alcohol in a film forming process by filtration. In this method, water is removed by filtration, and an organic solvent such as alcohol is added when the cellulose content reaches 5 to 99% by weight. Alternatively, the organic cellulose solvent such as alcohol can be replaced with the organic solvent such as alcohol at the end of the filtration by putting the fine cellulose fiber dispersion into the filtration device and then gently pouring the organic solvent such as alcohol into the upper part of the dispersion.

The organic solvent such as alcohol used here is not particularly limited, and examples thereof include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethylene glycol, ethylene glycol mono-t-butyl ether and the like. In addition to alcohols, one or more organic solvents such as acetone, methyl ethyl ketone, tetrahydrofuran, cyclohexane, toluene, carbon tetrachloride and the like can be mentioned. When using a water-insoluble organic solvent, it is preferable to use a water-soluble organic solvent or a mixed solvent with the water-soluble organic solvent, and then replace with a water-insoluble organic solvent.

Further, as a method for controlling the porosity, a method in which a solvent having a boiling point higher than that of the above-described alcohol is mixed and dried at a temperature lower than the boiling point of the solvent can be mentioned. In this case, if necessary, the solvent having a high boiling point remaining after drying is immersed in another solvent to be replaced and then dried.

<Film thickness>
Although there is no limitation in particular in the thickness of a cellulose nonwoven fabric, Preferably it is 1 micrometer or more, More preferably, it is 5 micrometers or more. Moreover, it is 1000 micrometers or less normally, Preferably it is 250 micrometers or less. The thickness of the cellulose nonwoven fabric is preferably not less than the above lower limit from the viewpoint of production stability and strength, and is preferably not more than the above upper limit from the viewpoint of productivity, uniformity, and resin impregnation. In addition, a film thickness can also be controlled by controlling the porosity of a cellulose nonwoven fabric by the above-mentioned method.

<Crystal structure>
The cellulose fibers in the cellulose nonwoven fabric preferably have a cellulose I-type crystal structure. Cellulose I-type crystals have a higher crystal elastic modulus than those of other crystal structures, and are therefore preferred as a cellulose nonwoven fabric having a high elastic modulus, high strength, and low linear expansion coefficient.

The fact that the cellulose fiber has the I-type crystal structure is a typical peak at two positions near 2θ = 14 to 17 ° and 2θ = 22 to 23 ° in the diffraction profile obtained by wide-angle X-ray diffraction image measurement. Can be identified.

<Number average fiber diameter>
The fiber diameter of the cellulose fibers in the cellulose nonwoven fabric is preferably 400 nm or less in terms of number average fiber diameter, more preferably 150 nm or less, further preferably 100 nm or less, and particularly preferably 80 nm or less. 50 nm or less is most preferable, and 30 nm or less is more preferable. Usually, it is 2 nm or more, and substantially 4 nm or more which is the fiber diameter of the cellulose crystal unit. Exceeding the upper limit is not preferable because the transparency decreases when the cellulose fiber composite material is formed.
As described above, this number average fiber diameter is usually observed with SEM, TEM, etc., and a diagonal line is drawn on the photograph, and 12 points are randomly extracted in the vicinity thereof, and the thickest fiber and the thinnest fiber are extracted. The 10 points from which the mark is removed are measured, and the measured values are averaged.

<Viscosity average degree of polymerization (degree of polymerization)>
In general, the higher the degree of polymerization of the cellulose fibers in the cellulose nonwoven fabric, the higher the elastic modulus and the higher strength the cellulose nonwoven fabric becomes, and this is preferable in terms of strength properties. The degree of polymerization of the cellulose fiber depends on the raw material used, but is 300 or more, preferably 1000 or more, more preferably 2000 or more.
The degree of polymerization of cellulose fibers in the cellulose nonwoven fabric can be calculated by measuring by the viscosity method described in TAPPI T230, as shown in the Examples section below.

[Method for producing chemically modified cellulose nonwoven fabric]
In the present invention, the cellulose in the cellulose nonwoven fabric is chemically modified using a reactive gas.

<Reactive gas>
The reactive gas in the present invention is a gas-state chemical modifier that reacts with a hydroxyl group in the cellulose nonwoven fabric to be chemically modified.
Therefore, any solid, liquid, or gas may be used at room temperature as long as it is in a gaseous state at the reaction temperature for chemical modification.

Examples of chemical modifiers include cyclic ethers such as acids, acid anhydrides, alcohols, halogenating reagents, isocyanates, alkoxysilanes, and oxiranes (epoxies).

Examples of the acid include acetic acid, acrylic acid, methacrylic acid, propanoic acid, butanoic acid, 2-butanoic acid, and pentanoic acid.

Examples of acid anhydrides include acetic anhydride, acrylic anhydride, methacrylic anhydride, propanoic anhydride, butanoic anhydride, 2-butanoic anhydride, pentanoic anhydride, benzoic anhydride, maleic anhydride, succinic anhydride, and fumaric anhydride. An acid, phthalic anhydride, glutaric anhydride, etc. are mentioned.

Examples of the halogenating reagent include acetyl halide, acryloyl halide, methacryloyl halide, propanoyl halide, butanoyl halide, 2-butanoyl halide, pentanoyl halide, benzoyl halide, naphthoyl halide, and benzyl chloride.

Examples of alcohol include methanol, ethanol, propanol, 2-propanol and the like.

Examples of the isocyanate include methyl isocyanate, ethyl isocyanate, propyl isocyanate and the like.

Examples of the alkoxysilane include methoxysilane and ethoxysilane.

Examples of cyclic ethers such as oxirane (epoxy) include ethyl oxirane and ethyl oxetane.

Among these, acids or acid anhydrides are preferable, and particularly in terms of reactivity and easy industrial application, acetic anhydride, propanoic acid anhydride, butanoic acid anhydride, acrylic acid anhydride, methacrylic acid anhydride, maleic anhydride, etc. An acid anhydride is preferably used.

These chemical modifiers may be used alone or in combination of two or more, and may be diluted with a solvent or the like as necessary.

<Pretreatment>
Prior to chemical modification of the cellulose nonwoven fabric, if necessary, the cellulose nonwoven fabric can be pretreated and then chemically modified using a reactive gas. Examples of the pretreatment method include a method of impregnating and immersing in a catalyst or a solvent, a method of immersing in an alkali such as sodium hydroxide, and converting a hydroxyl group of cellulose to a metal salt.

<Processing conditions>
The reaction temperature during the chemical modification is preferably 250 ° C. or less from the viewpoint of the thermal decomposition temperature of cellulose. If the reaction temperature is too high, there is concern about yellowing or a decrease in the degree of polymerization, and if it is too low, the reaction rate may decrease.
In particular, it is preferably 200 ° C. or lower, preferably 170 ° C. or lower, more preferably 150 ° C. or lower, and usually 10 ° C. or higher, preferably 80 ° C. or higher.
As in the present invention, for fibers having a small number average fiber diameter, controlling the reaction temperature is very important in obtaining a desired chemical modification rate and suppressing a decrease in the degree of polymerization of cellulose.
Here, the reaction temperature is the temperature in the reaction system.

The reaction pressure is not particularly limited as long as it reaches a vapor pressure at which the chemical modifier can be gasified at the reaction temperature. From the economical point of view, it is preferably normal pressure, but when the boiling point of the chemical modifier is equal to or higher than the reaction temperature, for example, the pressure is reduced to gasify the chemical modifier and the amount of steam is controlled. For this reason, it can be appropriately pressurized and depressurized.

The reaction time is usually 1 second or longer, preferably 1 minute or longer, more preferably 5 minutes or longer and 3 hours or shorter, preferably 2 hours or shorter, more preferably 90 minutes or shorter, even more preferably 1 hour or shorter. It can be appropriately changed depending on the type of chemical modifier (reactive gas) used and the required chemical modification rate.
Here, the reaction time refers to the time during which the gasified chemical modifier is in contact with the cellulose nonwoven fabric while the temperature in the reaction system has reached the required reaction temperature.

After the chemical modification is performed in this manner, the non-reacted chemical modifier attached to the cellulose nonwoven fabric is usually washed with water or warm water, and then the nonwoven fabric is dried. 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 the present invention, since the cellulose in the cellulose nonwoven fabric is chemically modified in the gas phase using a reactive gas, the amount of chemical modifier used is greatly reduced compared to the conventional chemical modification method in the liquid phase. be able to. Therefore, the amount of the chemical modifier remaining in the cellulose nonwoven fabric is also small, and the amount of water required for cleaning can be reduced. Further, since the amount of the remaining chemical modifier is small, it is possible to dry the chemically modified cellulose nonwoven fabric directly without passing through a process such as washing, and to simultaneously remove the chemical modifier and dry the nonwoven fabric.

The drying method is not particularly limited, but may be air drying, vacuum drying, or pressure drying. Moreover, you may heat-dry. When heating, 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. If the heating temperature is too low, drying takes time and drying may be insufficient. If the heating temperature is too high, the chemically modified cellulose nonwoven fabric may be colored or decomposed. Moreover, when pressurizing, 0.01 MPa or more is preferable, 0.1 MPa or more is more preferable, 5 MPa or less is preferable, and 1 MPa or less is more preferable. If the pressure is too low, drying may be insufficient, and if the pressure is too high, the chemically modified cellulose nonwoven fabric may be crushed and decomposed.

<Processing device>
As a processing apparatus used for chemical modification of a cellulose nonwoven fabric, it is preferable that the chemical modification of the cellulose in a cellulose nonwoven fabric can be implemented continuously or in large quantities from a viewpoint of industrial productivity.

Hereinafter, an apparatus capable of performing chemical modification of cellulose in a cellulose nonwoven fabric continuously or in large quantities will be described with reference to the drawings. However, the present invention is not limited to the one using the following denaturing device unless it exceeds the gist.

In the continuous cellulose denaturing apparatus 100 shown in FIG. 1, first, a reactive gas controlled to a predetermined temperature is supplied into the reaction apparatus 102 from the pipes 106a and 106b. Also in the reaction apparatus 102, the reactive gas is controlled to a predetermined temperature. Next, the cellulose nonwoven fabric 101 is supplied into the reaction apparatus 102 by the supply rollers 103a and 103b. Furthermore, the cellulose nonwoven fabric 101 is conveyed along the conveyance roller 104 in the reaction apparatus 102, and the cellulose in the cellulose nonwoven fabric 101 is chemically modified by the reactive gas in the meantime. Thereafter, the chemically modified cellulose nonwoven fabric discharged from the discharge rollers 105a and 105b is heated by the heater 108, and the remaining reactive gas is removed. The residual reactive gas may be removed by treating the chemically modified cellulose nonwoven fabric with superheated steam having a temperature equal to or higher than the boiling point of the reactive gas using the heater 108 as a superheated steam generator. Excess reactive gas in the reactor 102 is discharged from the pipe 107, cooled, recovered, separated, and recycled as reactive gas.

In the continuous denaturing apparatus 200 shown in FIG. 2, first, a reactive gas controlled to a predetermined temperature is supplied into the reaction apparatus 202 from a pipe 206a. Also in the reaction device 202, the reactive gas is controlled to a predetermined temperature. Next, the cellulose nonwoven fabric 201 is supplied into the reaction apparatus 202 by the supply rollers 203a and 203b. Furthermore, the cellulose nonwoven fabric 201 is conveyed in the reaction apparatus 202 along the conveyance roller 204, and the cellulose in the cellulose nonwoven fabric 201 is chemically modified by reactive gas in the meantime. Thereafter, the chemically modified cellulose nonwoven fabric discharged from the discharge rollers 205a and 205b is heated by the heater 208 to remove the remaining reactive gas. The residual reactive gas may be removed by treating the chemically modified cellulose nonwoven fabric with superheated steam at a temperature equal to or higher than the boiling point of the reactive gas using the heater 208 as a superheated steam generator. Excess reactive gas in the reactor 202 is discharged from the pipe 207, cooled, recovered, separated and recycled as reactive gas.

In the batch-type mass denaturing apparatus 300 shown in FIG. 3, first, a roll-shaped cellular roll nonwoven fabric 301 is put into a reaction apparatus 302, and then a reactive gas controlled to a predetermined temperature is supplied into the reaction apparatus 302 from a pipe 303. . The reactive gas is also controlled to a predetermined temperature in the reactor 302. The cellulose in the cellulose nonwoven fabric 301 is chemically modified by treating the roll-shaped cellulose nonwoven fabric 301 with a reactive gas controlled to a predetermined temperature for a predetermined time. In addition, the surplus reactive gas in the reaction apparatus 302 is discharged | emitted from the piping 304, is cooled, collect | recovered, isolate | separated, and is recycled as reactive gas.

[Characteristics of chemically modified cellulose nonwoven fabric]
The characteristics of the chemically modified cellulose nonwoven fabric of the present invention obtained by the above method will be described.

<Type of substituent>
Functional groups introduced into cellulose by chemical modification include acetyl, acryloyl, methacryloyl, propionyl, propioyl, butyryl, 2-butyryl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl , 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, noni Group, decyl group, undecyl group, dodecyl group, myristyl group, palmityl group, an alkyl group such as a stearyl group, an oxirane group, an oxetane group, a thiirane group, or the like thietane group. Of these, acyl groups having 2 to 12 carbon atoms such as acetyl group, acryloyl group, methacryloyl group, benzoyl group and naphthoyl group, and alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group and propyl group are particularly preferable. .

<Chemical modification rate>
The chemical modification rate of the chemically modified cellulose nonwoven fabric is preferably 5 mol% or more, more preferably 9 mol% or more, further preferably 10 mol% or more, particularly preferably 20 mol% or more, and 65 mol. % Or less, more preferably 50 mol% or less, still more preferably 40 mol% or less, and particularly preferably 30 mol% or less.
By chemically modifying the cellulose, the decomposition temperature of the cellulose increases and the heat resistance increases, but in the nonwoven fabric of the fiber having a small number average fiber diameter as in the present invention, if this chemical modification rate is too low, Insufficient heat resistance improvement effect, and may be colored when heated by post-combination. If the chemical modification rate is too high, the cellulose structure is destroyed and the crystallinity is lowered. There is a problem that the linear expansion coefficient of the composite material becomes large, which is not preferable. On the other hand, when the chemical modification rate is too low, the hydrophilicity of the non-woven fabric increases and the water content increases, which is not preferable. In particular, when wood is used as the cellulose fiber raw material, if the chemical modification rate is low, it will be colored when heated by post-processing of the composite, or even if the chemical modification rate is high, the nonwoven fabric will be colored after the chemical modification reaction. It is not preferable because it is lost.

Here, the chemical modification rate refers to the proportion of all hydroxyl groups in cellulose that have been chemically modified, and the chemical modification rate can be measured by the following titration method.

<Measuring method>
0.05 g of chemically modified cellulose nonwoven fabric is precisely weighed, and 0.5 ml of distilled water and 1.5 ml of ethanol are added thereto. This is allowed to stand for 30 minutes in a hot water bath at 60 to 70 ° C., and then 2 ml of 0.5 M 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 0.1 M hydrochloric acid standard solution using an automatic titrator (Mitsubishi Chemical Corporation: GT-100).
Here, from the amount Z (ml) of the 0.1 M aqueous hydrochloric acid solution required for the titration, the number of moles Q (mol) of the substituent introduced by chemical modification is determined by the following formula.
Q (mol) = 0.5 (N) × 2 (ml) / 1000
-0.1 (N) x Z (ml) / 1000
The relationship between the number of moles Q of the substituent and the chemical modification rate X (mol%) is calculated by the following formula (cellulose = (C ₆ O ₅ H ₁₀ ) _n = (162.14) _n , repetition Number of hydroxyl groups per unit = 3, molecular weight of OH = 17). In the following, T is the molecular weight of the substituent.

When solving this, it becomes as follows.

<Crystal structure>
The cellulose fibers in the chemically modified cellulose nonwoven fabric preferably have a cellulose I-type crystal structure. Cellulose I-type crystals are preferable because they have higher crystal elastic modulus than other crystal structures, and thus have high elastic modulus, high strength, and low linear expansion coefficient.
The fact that the cellulose fiber has the I-type crystal structure is a typical peak at two positions near 2θ = 14 to 17 ° and 2θ = 22 to 23 ° in the diffraction profile obtained by wide-angle X-ray diffraction image measurement. Can be identified.

<Viscosity average degree of polymerization (degree of polymerization)>
The larger the degree of polymerization of the cellulose fibers in the chemically modified cellulose nonwoven fabric, the higher the elastic modulus and the higher the strength, which is preferable in terms of strength properties. The degree of polymerization depends on the raw materials used, but is 300 or more, preferably 1000 or more, more preferably 2000 or more.

As shown in the examples below, according to the present invention, the rate of decrease in the degree of polymerization of cellulose in the chemically modified cellulose nonwoven fabric after chemical modification relative to the degree of polymerization of cellulose in the cellulose nonwoven fabric before chemical modification is: It can be suppressed to 10% or less.
The polymerization degree of the cellulose fiber in the chemically modified cellulose nonwoven fabric can be calculated by measuring by the viscosity method described in TAPPI T230, as shown in the Examples section described later.

<Application>
The chemically modified cellulose nonwoven fabric produced as described above can be used in combination with a matrix material as described in detail below, or only the chemically modified cellulose nonwoven fabric itself. For example, separators for power storage devices, medical separation membranes, packaging materials, various filters, and the like can be given.

[Cellulose fiber composite material]
The cellulose fiber composite material of the present invention contains a chemically modified cellulose nonwoven fabric obtained by the production method of the present invention and a matrix material. The cellulose fiber composite material is useful for various display substrate materials, solar cell substrates, window materials and the like by taking advantage of its high transparency, low linear expansion coefficient, and non-coloring properties. Utilizing characteristics such as elastic modulus, low linear expansion coefficient, and surface smoothness, it is useful for various structural materials, particularly for automobile panels having excellent surface design and for building outer wall panels.

Here, the matrix material refers to a polymer material or a precursor thereof (for example, a monomer) that is bonded to a chemically modified cellulose nonwoven fabric or that fills voids.

Suitable as the matrix material is a thermoplastic resin that becomes a fluid liquid by heating, a thermosetting resin that polymerizes by heating, and is cured by irradiation with active energy rays such as ultraviolet rays and electron beams. , At least one resin (polymer material) selected from active energy ray-curable resins and the like, or a precursor thereof. In the present invention, a cellulose fiber resin composite material can be obtained by combining chemically modified cellulose and a resin.
In the present invention, the precursor of the resin (polymer material) is a so-called monomer or oligomer.

The cellulose fiber composite material of the present invention is usually obtained by compositing a chemically modified cellulose nonwoven fabric obtained by the production method of the present invention and a matrix material, and examples of the composite method include the following methods.
(A) A method in which a chemically modified cellulose nonwoven fabric is impregnated with a liquid thermoplastic resin precursor and polymerized (b) A chemically modified cellulose nonwoven fabric is impregnated with a thermosetting resin precursor or a photocurable resin precursor and polymerized. Method of curing (c) Resin solution (solution containing one or more solutes selected from thermoplastic resins, thermoplastic resin precursors, thermosetting resin precursors, and photocurable resin precursors) on chemically modified cellulose nonwoven fabric (D) Method of impregnating a chemically modified cellulose non-woven fabric with a thermoplastic resin melt and adhering it with a heating press or the like ( e) A method in which thermoplastic resin sheets and chemically modified cellulose nonwoven fabrics are alternately arranged and adhered with a hot press or the like (f) Liquid on one side or both sides of the chemically modified cellulose nonwoven fabric (G) A resin solution (thermoplastic resin, thermoplastic resin) on one or both sides of a chemically modified cellulose nonwoven fabric by applying a thermoplastic resin precursor, a thermosetting resin precursor, or a photocurable resin precursor to polymerize and cure A solution containing one or more solutes selected from a precursor, a thermosetting resin precursor, and a photocurable resin precursor) is applied, and after removing the solvent, it is combined by polymerizing and curing as necessary. Method

Although matrix materials other than cellulose are exemplified below, the matrix material used in the present invention is not limited to the following materials. In addition, the thermoplastic resin, thermosetting resin, and light (active energy ray) curable resin in the present invention can be used in combination of two or more.

In the present invention, among the following matrix materials (polymer materials or precursors thereof), in the case of a polymer material or precursor, the polymer is an amorphous compound having a high glass transition temperature (Tg). A polymer is preferable for obtaining a highly durable cellulose fiber composite material having excellent transparency. Among these, the degree of amorphousness is 10% or less, particularly 5% or less in terms of crystallinity. The Tg is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 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. Moreover, in order to obtain a low water-absorbing cellulose fiber composite material, it is preferable to select a polymer material having few hydrophilic functional groups such as a hydroxyl group, a carboxyl group, and an amino group. The polymer Tg can be determined by a general method. For example, it is obtained by measurement by the DSC method. The degree of crystallinity of the polymer can be calculated from the density of the amorphous part and the crystalline part, and can also be calculated from the tan δ, which is the ratio of the elastic modulus to the viscosity, by dynamic viscoelasticity measurement. .

<Thermoplastic resin>
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, amorphous fluorine resin and the like.

<Thermosetting resin>
The thermosetting resin is not particularly limited, but includes epoxy resin, acrylic resin, oxetane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicon resin, polyurethane resin, diallyl phthalate resin, etc. A precursor is mentioned.

<Photocurable resin>
Although it does not specifically limit as photocurable resin, Precursors, such as an epoxy resin illustrated in the description of the above-mentioned thermosetting resin, an acrylic resin, an oxetane resin, are mentioned.

Specific examples of the thermoplastic resin, thermosetting resin, and photocurable resin include those described in Japanese Patent Application Laid-Open No. 2009-299043.

<Other ingredients>
The thermosetting resin and the photocurable resin are appropriately used as a curable composition blended with a chain transfer agent, an ultraviolet absorber, a filler, a silane coupling agent and the like.

<Laminated structure>
The cellulose fiber composite material of the present invention may be a laminated structure of a layer of the chemically modified cellulose nonwoven fabric of the present invention and a planar structure layer made of a polymer other than cellulose, and the chemically modified cellulose of the present invention. A laminated structure of the nonwoven fabric layer and the cellulose fiber composite material layer of the present invention may be used, and the number of laminated layers and the laminated structure are not particularly limited.

<Inorganic membrane>
The cellulose fiber composite material of the present invention may be obtained by further laminating an inorganic film on the cellulose fiber composite material layer according to its use, and further laminating an inorganic film on the above laminated structure. There may be.
The inorganic film used here is appropriately determined according to the use of the cellulose fiber composite material, for example, metal such as platinum, silver, aluminum, gold, copper, silicon, ITO, SiO ₂ , SiN, SiOxNy, ZnO, etc. A TFT etc. are mentioned, The combination and film thickness can be designed arbitrarily.

<Characteristics and physical properties of cellulose fiber composite material>
Hereinafter, suitable characteristics or physical properties of the cellulose fiber composite material of the present invention will be described.

(Cellulose content)
The cellulose content (cellulose fiber content) in the cellulose fiber composite material of the present invention is usually 1% by weight to 99% by weight, and the content of the matrix material other than cellulose is 1% by weight to 99% by weight. It is. In order to develop low linear expansion, it is necessary that the content of cellulose is 1% by weight or more and the content of a matrix material other than cellulose is 99% by weight or less. In order to express transparency, it is necessary that the content of cellulose is 99% by weight or less and the content of a matrix material other than cellulose is 1% by weight or more. A preferred range is 5% to 90% by weight of cellulose, a matrix material other than cellulose is 10% to 95% by weight, and a more preferred range is 10% to 80% by weight of cellulose, The matrix material other than cellulose is 20% by weight or more and 90% by weight or less. In particular, the content of cellulose is preferably 30% by weight or more and 70% by weight or less, and the content of matrix materials other than cellulose is preferably 30% by weight or more and 70% by weight or less.

The content of cellulose and a matrix material other than cellulose in the cellulose fiber composite material can be determined, for example, from the weight of the cellulose nonwoven fabric before composite and the weight of the cellulose fiber composite material after composite. Alternatively, the cellulose fiber composite material can be immersed in a solvent in which the matrix material is soluble to remove only the matrix material, and the weight can be determined from the weight of the remaining cellulose fibers. In addition, the functional group of the resin or cellulose can also be quantified and determined using the specific gravity of the resin that is the matrix material, NMR, or IR.

(Thickness)
The thickness of the cellulose fiber composite material of the present invention is preferably 10 μm or more and 10 cm or less, and by using such a thickness, the strength as a structural material can be maintained. The thickness of the cellulose fiber composite material is more preferably 50 μm or more and 1 cm or less, and further preferably 80 μm or more and 250 μm or less.
The cellulose fiber composite material of the present invention is, for example, a film shape (film shape) or a plate shape having such a thickness, but is not limited to a flat film or a flat plate, and is a film shape or a plate shape having a curved surface. You can also Other irregular shapes may also be used. Further, the thickness is not necessarily uniform and may be partially different.

(Coloring)
The cellulose fiber composite material of the present invention is characterized in that coloring by heating is small.
Cellulose is sometimes yellowish by using raw materials derived from wood. This may be the case where the cellulose itself is colored or the remaining substance other than cellulose depending on the degree of purification. The cellulose fiber composite material of the present invention is small in color even when a heating step is performed, and can withstand heat treatment in an actual device forming step such as a transparent substrate of various devices.
When the cellulose fiber composite material of the present invention is used as various transparent materials, the degree of coloring of the cellulose fiber is preferably 15 or less, more preferably 10 or less, as the YI of the cellulose fiber composite material measured in the section of the examples described later. It is preferable that the YI does not increase even after the heat treatment, and it is preferable that the YI is maintained at 15 or less, particularly 10 or less after the heat treatment.

(Haze)
The cellulose fiber composite material of the present invention can be a cellulose fiber composite material having high transparency, that is, low haze.
When used as various transparent materials, the haze of the cellulose fiber composite material is preferably 5.0 or less, more preferably 3.0 or less, and this value is particularly preferably 2.0 or less. When the haze is larger than 5.0, it becomes difficult to apply to a transparent substrate of various devices.
The haze can be measured, for example, for a cellulose fiber composite material having a thickness of 10 to 100 μm using a haze meter manufactured by Suga Test Instruments, and the value of C light is used.

(Total light transmittance)
The cellulose fiber composite material of the present invention can be a cellulose fiber composite material having high transparency, that is, low haze. When used as various transparent materials, the cellulose fiber composite material has a total light transmittance of 60% or more, further 70% or more, particularly 80% or more, particularly 90%, as measured in the thickness direction in accordance with JIS K7105. % Or more is preferable. 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, for a cellulose fiber composite material having a thickness of 10 to 100 μm using a haze meter manufactured by Suga Test Instruments, and the value of C light is used.

(Linear expansion coefficient)
The cellulose fiber composite material of the present invention can be made into a cellulose fiber composite material having a low linear expansion coefficient by using cellulose having a low linear expansion coefficient (elongation rate per 1K). The linear expansion coefficient of the cellulose fiber composite material is preferably 1 to 50 ppm / K, more preferably 1 to 40 ppm / K, although it depends on the type of matrix material and the cellulose fiber content. Particularly preferred is / K.
That is, for example, in the substrate application, since the linear expansion coefficient of the inorganic thin film transistor is about 15 ppm / K, when the linear expansion coefficient of the cellulose fiber composite material exceeds 50 ppm / K, the laminated composite with the inorganic film is formed. The difference in linear expansion coefficient between the two layers becomes large, and cracks and the like are generated. Accordingly, the linear expansion coefficient of the cellulose fiber composite material is particularly preferably 1 to 30 ppm / K.
In addition, a linear expansion coefficient is measured by the method described in the term of the below-mentioned Example.

(Tensile strength)
The tensile strength of the cellulose fiber composite material 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.

(Tensile modulus)
The tensile elastic modulus of the cellulose fiber composite material of the present invention depends on the type and use of the matrix material to be composited, but is preferably 0.2 to 100 GPa, more preferably 1 to 50 GPa, still more preferably 5.0 to 30 GPa. It is. When the tensile elastic modulus is lower than 0.2 GPa, sufficient strength cannot be obtained, which may affect the use of a structural material or the like to which a force is applied.
In particular, according to the method for producing a chemically modified cellulose nonwoven fabric of the present invention, the chemically modified cellulose nonwoven fabric and the cellulose fiber composite material obtained by reducing the reaction time of the chemical modification and preventing the degradation of the polymerization degree of cellulose during the reaction are obtained. It is possible to maintain a high tensile elastic modulus.

<Application>
The cellulose fiber composite material of the present invention has high transparency, high strength, low water absorption, high transparency, low coloration, small haze, and excellent optical properties, so that it can be used for liquid crystal displays, plasma displays, organic EL displays, field emission displays. It is suitably used as an optical member such as substrates for various display devices such as rear projection televisions, panels, polarizing films, antireflection films, hard coat films, and retardation films. Moreover, it is also suitable as a base material for lighting such as organic EL lighting.
Moreover, it is suitable for substrates for solar cells such as silicon-based solar cells and dye-sensitized solar cells. The substrate may be laminated with a barrier film, ITO, TFT or the like. In particular, the cellulose fiber composite material of the present invention is small in color even when heated, and can withstand heat treatment in actual device forming steps such as transparent substrates of various devices.
The cellulose fiber composite material of the present invention can also be suitably used for window materials for automobiles, window materials for railway vehicles, window materials for houses, window materials for offices and factories, and the like. As the window material, a film such as a fluorine film or a hard coat film or a material having impact resistance or light resistance may be laminated as necessary.
In addition, the cellulose fiber composite material of the present invention can be used as a structure other than the use of a transparent material by taking advantage of characteristics such as a low linear expansion coefficient, high elasticity, and high strength. In particular, it is suitably used as automobile materials such as interior materials, outer plates, bumpers, etc., personal computer casings, home appliance parts, packaging materials, building materials, civil engineering materials, marine materials, and other industrial materials.

Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Evaluation methods]
The chemical modification rate of the chemically modified cellulose nonwoven fabric of the present invention, the degree of polymerization, the cellulose content of the composite material using the chemically modified cellulose nonwoven fabric, haze, total light transmittance, YI and the method of measuring the linear expansion coefficient are as follows. .

<Chemical modification rate>
It was measured by the method described in detail above.

<Degree of polymerization and rate of decrease in degree of polymerization>
The degree of polymerization was measured by the viscosity method described in TAPPI T230.
0.04 g of cellulose nonwoven fabric is precisely weighed, 10 mL of water and 10 mL of 1M copper ethylenediamine aqueous solution are added thereto, and stirred for about 5 minutes to dissolve the cellulose. The dissolved solution is put into an Ubbelohde type viscosity tube, and the flow rate is measured at 25 ° C. Using a mixed solution of 10 mL of water and 1M copper ethylenediamine aqueous solution as a blank, the intrinsic viscosity [η] is determined. Using this, the viscosity average degree of polymerization was calculated according to the following formula described in the wood science experiment manual.
Viscosity average degree of polymerization = 175 × [η]
Moreover, the polymerization degree of the cellulose nonwoven fabric before chemical modification and the polymerization degree of the cellulose nonwoven fabric after chemical modification were measured, and the degree of polymerization degree reduction after chemical modification with respect to before chemical modification was calculated according to the following formula.

<Tensile modulus of chemically modified cellulose nonwoven fabric>
The composite material was cut into 8 mm width × 40 mm length. This was subjected to a tensile test using a STA-1225 manufactured by Orientec Co., Ltd. at a distance between chucks of 15 mm and a test speed of 2 mm / min to obtain a tensile elastic modulus.

<Cellulose content in cellulose fiber composite material>
The cellulose content (% by weight) was determined from the weight of the chemically modified cellulose nonwoven fabric used for the composite and the weight of the obtained cellulose fiber composite material.

<Haze of cellulose fiber composite material>
The haze value by C light was measured using a Suga Test Instruments haze meter.

<YI value of cellulose fiber composite material>
The YI value was measured using a color computer manufactured by Suga Test Instruments.

<Linear expansion coefficient of cellulose fiber composite material>
The composite material was cut into 3 mm width × 40 mm length with a laser cutter. This was pulled using a TMA6100 made by SII in a pulling mode at a chucking distance of 20 mm, a load of 10 g and a nitrogen atmosphere from room temperature to 180 ° C. at 5 ° C./min. And then from 180 ° C. to 25 ° C. at 5 ° C./min. At 25 ° C. and then from 25 ° C. to 180 ° C. The linear expansion coefficient was determined from the measured value from 60 ° C. to 100 ° C. during the second temperature increase.

<Tensile elastic modulus of cellulose fiber composite material>
The composite material was cut into a 10 mm width × 40 mm length by a laser cutter. This was subjected to DMA (dynamic viscoelasticity) measurement in tensile mode using DMS6100 manufactured by SII, and storage elastic modulus E ′ (unit: GPa) at a frequency of 10 Hz and 23 ° C. was measured.

<Production Example 1: Production of Cellulose Fiber Raw Material 1>
Wood flour (Miyashita Wood Co., Ltd., Yonematsu) was degreased at 90 ° C. for 5 hours with stirring in a 2 wt% sodium carbonate aqueous solution. After washing this with demineralized water, an aqueous peracid solution in which acetic anhydride and 30% by weight of hydrogen peroxide were mixed at a volume ratio of 1: 1 was added, followed by delignification at 90 ° C. for 1 hour. After washing with demineralized water, the cellulose fiber raw material 1 was obtained by further immersing in a 5 wt% aqueous potassium hydroxide solution for 24 hours to dehemicellulose, and washing with demineralized water.

<Production Example 2: Production of Cellulose Fiber Raw Material 2>
Wood flour (Miyashita Wood Co., Ltd., Yonematsu) was degreased with a 2 wt% aqueous sodium carbonate solution at 80 ° C. for 6 hours. This was washed with demineralized water, and then subjected to delignification treatment with sodium chlorite under acetic acid acidity at 80 ° C. for 5.5 hours. After washing with demineralized water, the cellulose fiber raw material 2 was obtained by further immersing in a 5 wt% aqueous potassium hydroxide solution for 16 hours to dehemicellulose and washing with demineralized water.

<Production Example 3: Production of Cellulose Nonwoven Fabric 1>
Cellulose fiber raw material 1 obtained in Production Example 1 was diluted with water to a concentration of 0.5% by weight and dissolved using a high-speed rotating homogenizer (M Technique Co., Ltd .: CLM0.8S) at a rotational speed of 2000 rpm for 60 minutes. Fiber processing was performed to obtain a fine cellulose fiber dispersion.
The obtained fine cellulose fiber dispersion was diluted with water to a concentration of 0.13% by weight, and 150 g was put into a 90 mm diameter filter using PTFE having a pore diameter of 1 μm, and when the solid content became about 5 wt%, 2 -Replaced with 30 ml of propanol. Then, it press-dried at 120 degreeC and 0.14 MPa for 5 minutes, and the white cellulose nonwoven fabric 1 was obtained. The number average fiber diameter of the cellulose fibers of this cellulose nonwoven fabric 1 was 18 nm.

<Production Example 4: Production of Cellulose Nonwoven Fabric 2>
Cellulose fiber raw material 1 obtained in Production Example 1 was diluted with water to a concentration of 0.5% by weight and dissolved using a high-speed rotating homogenizer (M Technique Co., Ltd .: CLM0.8S) at a rotational speed of 2000 rpm for 60 minutes. Fiber processing was performed to obtain a fine cellulose fiber dispersion.
Furthermore, ultrasonic treatment was performed using an ultrasonic homogenizer (manufactured by SMT: UH-600S, frequency 20 kHz, effective output density 22 W / cm ² ). Using a 36 mmφ straight tip (made of titanium alloy), tuning was performed with the output volume 8, and ultrasonic treatment was performed for 30 minutes at the optimum tuning position. The cellulose fiber raw material dispersion was cooled with cold water at 5 ° C. from the outside of the processing vessel, and was processed while stirring with a magnetic stirrer.
This ultrasonically treated cellulose fiber raw material dispersion was centrifuged to obtain a supernatant. A centrifuge (manufactured by Hitachi Koki Co., Ltd .: himacCR22G) was used, and R20A2 was used as an angle rotor. Eight 50 ml centrifuge tubes were installed at an angle of 34 degrees from the rotation axis. The amount of the cellulose fiber raw material dispersion placed in one centrifuge tube was 30 ml. Centrifugation was performed at 18000 rpm for 30 minutes, and the supernatant was collected.
The obtained fine cellulose fiber dispersion was diluted with water to a concentration of 0.13% by weight, and 150 g was put into a 90 mm diameter filter using PTFE having a pore diameter of 1 μm, and when the solid content became about 5 wt%, 2 -Replaced with 30 ml of propanol. Then, it press-dried at 120 degreeC and 0.14 MPa for 5 minutes, and the white cellulose nonwoven fabric 2 was obtained. The number average fiber diameter of the cellulose fibers of the cellulose nonwoven fabric 2 was 14 nm.

<Production Example 5: Production of cellulose nonwoven fabric 3>
In Production Example 3, the same treatment was performed except that the cellulose fiber raw material 2 obtained in Production Example 2 was used in place of the cellulose fiber raw material 1, and a cellulose nonwoven fabric 3 was obtained. The number average fiber diameter of the cellulose fibers of this cellulose nonwoven fabric 3 was 18 nm.

<Example 1>
Cellulose nonwoven fabric 1 was placed in a container containing 100 mL of acetic anhydride so as not to come into contact with the liquid and sealed. The vessel was heated to 135 ° C., the vapor temperature in the vessel (reaction system temperature) was raised to 130 ° C., and acetic anhydride vapor was brought into contact with the cellulose nonwoven fabric for 10 minutes (treatment time) to carry out the reaction. After the reaction, the cellulose nonwoven fabric was taken out, washed thoroughly with distilled water, immersed in acetone for 10 minutes, and then press dried at 120 ° C. and 0.14 MPa for 3 minutes to obtain an acetylated cellulose nonwoven fabric. The resulting nonwoven fabric had a chemical modification rate of 20.0 mol%.

<Example 2>
An acetylated cellulose nonwoven fabric was obtained in the same manner as in Example 1 except that the reaction time (treatment time) for chemically modifying the cellulose nonwoven fabric 1 was 30 minutes. The chemical modification rate of the obtained nonwoven fabric was 44.3 mol%.

<Example 3>
Acetylated cellulose nonwoven fabric in the same manner as in Example 1 except that the vapor temperature (temperature in the reaction system) in the container when chemically modifying the cellulose nonwoven fabric 1 is 140 ° C. and the reaction time (treatment time) is 10 minutes. Got. The chemical modification rate of the obtained nonwoven fabric was 38.7 mol%.

<Example 4>
Example 1 except that the cellulose nonwoven fabric 2 is used in place of the cellulose nonwoven fabric 1 and the vapor temperature (reaction system temperature) in the container for chemical modification is 130 ° C. and the reaction time (treatment time) is 20 minutes. Similarly, an acetylated cellulose nonwoven fabric was obtained. The chemical modification rate of the obtained nonwoven fabric was 28.7 mol%.

<Example 5>
Example 1 except that the cellulose nonwoven fabric 3 is used in place of the cellulose nonwoven fabric 1 and the vapor temperature (reaction system temperature) in the container for chemical modification is 130 ° C. and the reaction time (treatment time) is 20 minutes. Similarly, an acetylated cellulose nonwoven fabric was obtained. The chemical modification rate of the obtained nonwoven fabric was 33.0 mol%.

<Comparative Example 1>
Cellulose nonwoven fabric 1 was immersed in a container containing 700 mL of acetic anhydride and sealed. The container was heated to 135 ° C. and reacted at a liquid temperature (temperature in the reaction system) in the container of 130 ° C. for 30 minutes (treatment time). After the reaction, the cellulose nonwoven fabric was taken out and washed well with 2-propanol to remove excess acetic anhydride. Thereafter, it was thoroughly washed with distilled water, immersed in 2-propanol for 10 minutes, and then press-dried at 120 ° C. and 0.14 MPa for 5 minutes to obtain an acetylated cellulose nonwoven fabric. The chemical modification rate of the obtained nonwoven fabric was 4.3 mol%.

<Comparative example 2>
Acetylated cellulose nonwoven fabric in the same manner as in Comparative Example 1 except that the liquid temperature (reaction system temperature) in the container when chemically modifying the cellulose nonwoven fabric 1 is 110 ° C. and the reaction time (treatment time) is 420 minutes. Got. The chemical modification rate of the obtained nonwoven fabric was 24.3 mol%.

<Comparative Example 3>
Comparative Example 1 except that the cellulose nonwoven fabric 2 is used instead of the cellulose nonwoven fabric 1 and the liquid temperature (reaction system temperature) in the container for chemical modification is 110 ° C. and the reaction time (treatment time) is 420 minutes. Similarly, an acetylated cellulose nonwoven fabric was obtained. The chemical modification rate of the obtained nonwoven fabric was 27.3 mol%.

<Comparative Example 4>
Comparative Example 1 except that the cellulose nonwoven fabric 3 is used in place of the cellulose nonwoven fabric 1, and the liquid temperature (reaction system temperature) in the container for chemical modification is 130 ° C. and the reaction time (treatment time) is 120 minutes. Similarly, an acetylated cellulose nonwoven fabric was obtained. The chemical modification rate of the obtained nonwoven fabric was 27.0 mol%.

The results obtained in Examples 1 to 5 and Comparative Examples 1 to 4 are summarized in Table 1.

As is clear from Table 1, according to the method for producing a chemically modified cellulose nonwoven fabric of the present invention using a reactive gas, the reaction time for chemical modification is shortened compared to the conventional reaction method in which the reaction solution is immersed. Moreover, the washing | cleaning process which removes an excess reaction liquid after reaction can be skipped, and not only the process can be simplified, but the amount of solvent used can be reduced.

<Example 6>
The degree of polymerization, the degree of polymerization degree reduction, and the tensile modulus of the chemically modified cellulose nonwoven fabric obtained in Example 4 were measured. The degree of polymerization was 1097, the rate of decrease in the degree of polymerization was 6.1%, and the tensile modulus was 3.0 GPa.
Next, a cellulose fiber composite material was produced using this chemically modified cellulose nonwoven fabric.
100 parts by weight of 1,10-decanediol diacrylate, 0.24 parts by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASF's Lucillin TPO), hydroxycyclohexyl phenyl ketone (Ciba The mixed solution was impregnated with 0.1 part by weight of Irgacure 184 manufactured by Specialty Chemicals, and placed under reduced pressure for 1 hour. This was sandwiched between two glass plates and irradiated under an irradiance of 400 mW / cm ² at a line speed of 7 m / min using an electrodeless mercury lamp (“D bulb” manufactured by Fusion UV Systems). The irradiation dose at this time was 0.12 J / cm ² . This operation was performed twice by inverting the glass surface. The temperature of the glass surface after ultraviolet irradiation was 25 ° C. Next, irradiation was performed under an irradiance of 1900 mW / cm ^{2 at} a line speed of 2 m / min. The irradiation dose at this time was 2.7 J / cm ² . This operation was performed 4 times by inverting the glass surface. The temperature of the glass surface after ultraviolet irradiation was 50 ° C. The irradiation dose was 21.8 J / cm ² . After the ultraviolet irradiation was completed, the glass plate was removed and heated in an oven (nitrogen gas atmosphere) at 200 ° C. for 4 hours to obtain a composite material. The irradiance of ultraviolet rays was measured at 23 ° C. by using an ultraviolet illuminance meter “UV-M02” manufactured by Oak Seisakusho and using an attachment “UV-35”.
The obtained composite material has a cellulose content of 53.0% by weight, a thickness of 90 μm, a haze of 3.1, a total light transmittance of 89.2%, a YI of 7.7, and a linear expansion coefficient of 20.4 ppm. / K, the tensile modulus was 4.6 GPa.

<Comparative Example 5>
The degree of polymerization, the degree of polymerization degree reduction, and the tensile modulus of the chemically modified cellulose nonwoven fabric obtained in Comparative Example 3 were measured. The degree of polymerization was 930, the rate of decrease in the degree of polymerization was 20.4%, and the tensile modulus was 2.2 GPa.
Next, a cellulose fiber composite material was produced in the same manner as in Example 6 using this chemically modified cellulose nonwoven fabric. The obtained composite material has a cellulose content of 45.1% by weight, a thickness of 96 μm, a haze of 3.1, a total light transmittance of 90.6%, a YI of 5.4, and a linear expansion coefficient of 24.2 ppm. / K, the tensile elastic modulus was 2.8 GPa.

The results obtained in Example 6 and Comparative Example 5 are summarized in Table 2.

From Table 2, the physical properties of the chemically modified cellulose nonwoven fabric obtained by the production method of the chemically modified cellulose nonwoven fabric of the present invention using reactive gas are more polymerized than the chemically modified cellulose nonwoven fabric obtained by the reaction method immersed in the conventional reaction solution. As a result, a chemically modified cellulose nonwoven fabric having a high tensile elastic modulus can be obtained. As for the physical properties of the cellulose fiber composite material, a composite material excellent in transparency, non-coloring property, low linear expansion coefficient, and tensile elastic modulus was obtained as in the past. The tensile modulus was improved as compared with the conventional method, and the linear expansion coefficient was also decreased as compared with the conventional method. That is, according to the present invention, it can be seen that a highly transparent, non-colorable, high heat resistant, low linear expansion coefficient, high strength composite material is produced with high productivity.

<Production Example 6: Production of cellulose nonwoven fabric 4>
Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd.) was beaten using a disc refiner (manufactured by Kumagai Rika Kogyo). The above beaten pulp is diluted with water to a concentration of 2% by weight and subjected to a defibration treatment at a rotational speed of 6500 rpm for 2 hours using a high-speed rotating homogenizer (M Technique Co., Ltd .: CLM11S) to obtain a fine cellulose fiber dispersion. Obtained.
The obtained fine cellulose fiber dispersion was diluted with water to a concentration of 0.2% by weight and ethylene glycol mono-tert-butyl ether (24 times the amount of dry fine cellulose fibers (g)) was A4. The paper was put into a size paper machine (manufactured by Oji Paper Co., Ltd.), paper-dried, and dried with a cylinder dryer heated to 120 ° C. to obtain a cellulose nonwoven fabric 4 having a basis weight of 35 g / m ² and A4 size. The number average fiber diameter of the cellulose fibers of this cellulose nonwoven fabric 4 was 28 nm.

<Example 7>
In a container containing 20 mL of acetic anhydride, 12 pieces of the cellulose nonwoven fabric 4 obtained in Production Example 6 were rolled up into a cylinder and sealed in a container so as not to come into contact with the liquid. The container was heated to 145 ° C., the temperature in the container was raised to 140 ° C., and the vapor of acetic anhydride was brought into contact with the cellulose nonwoven fabric 4 for 60 minutes (treatment time) to carry out the reaction. After the reaction, the residue was dried with a hot air dryer at 140 ° C. to remove residual gas. The chemical modification rate of the obtained cellulose nonwoven fabric was 9.7 mol% for the outermost cellulose nonwoven fabric rolled into a cylindrical shape, and 10.0 mol% for the innermost cellulose nonwoven fabric.

<Example 8>
93 sheets of A4 size cellulose nonwoven fabric 4 obtained in Production Example 6 were cut into a size of 4 cm × 4 cm. As shown in FIG. 4, this cellulose nonwoven fabric 401 (cellulose nonwoven fabric obtained in Production Example 6) was prepared. 4) was layered, and Kapton tape 402 was wound around it to obtain a block-shaped cellulose nonwoven fabric 405. As shown in FIG. 5, this is a reproduction of a part of a cellulose nonwoven fabric 401 wound into a 30-m roll.
In addition, when the thickness of the cellulose nonwoven fabric 401 is about 70 μm and the outer diameter of the winding core is 96.2 mm, when the cellulose nonwoven fabric 401 is wound into a 30-m roll, the paper thickness D becomes 6.5 mm.
The block-shaped cellulose nonwoven fabric was placed in a container in a container containing 20 mL of acetic anhydride and sealed so as not to come into contact with the liquid. The container was heated to 145 ° C., the temperature in the container was raised to 140 ° C., and acetic anhydride vapor was brought into contact with the block-shaped cellulose nonwoven fabric for 90 minutes (treatment time) to carry out the reaction. After the reaction, the residue was dried with a hot air dryer at 140 ° C. to remove residual gas. The chemical modification rate of the obtained cellulose nonwoven fabric was 11.7 mol% at 0 m equivalent (top), 11.3 mol% at 10 m, 10.3 mol% at 15 m, 10.0 mol% at 20 m , 30 m equivalent (lowermost part) was 11.3 mol%.

From the above results, according to the method for producing a chemically modified cellulose nonwoven fabric of the present invention, even if the cellulose nonwoven fabric is rolled and chemically modified, a cellulose nonwoven fabric having a desired chemical modification rate is obtained uniformly throughout the nonwoven fabric. I found out that
Thereby, it becomes possible to manufacture a chemically modified cellulose nonwoven fabric with high productivity.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on Oct. 17, 2011 (Japanese Patent Application No. 2011-228102), the contents of which are incorporated herein by reference.

100, 200, 300

Modification device

101, 201, 301, 401

Cellulose nonwoven fabric

102, 202, 302

Reactor

108, 208 Heater 402 Kapton tape 405 Block-like cellulose nonwoven fabric D Paper thickness

Claims

A method for producing a chemically modified cellulose nonwoven fabric,
Using a cellulose nonwoven fabric of cellulose fibers having a number average fiber diameter of 2 to 400 nm,
The manufacturing method of chemically modifying the cellulose in the said cellulose nonwoven fabric using reactive gas.
The method for producing a chemically modified cellulose nonwoven fabric according to claim 1, wherein the reactive gas is a gaseous acid or acid anhydride.
The manufacturing method of the chemically modified cellulose nonwoven fabric of Claim 1 or Claim 2 which makes the said reactive gas contact with a roll-shaped cellulose nonwoven fabric.
The method for producing a chemically modified cellulose nonwoven fabric according to any one of claims 1 to 3, wherein a temperature in the reaction system when chemically modifying with the reactive gas is 250 ° C or lower.
The method for producing a chemically modified cellulose nonwoven fabric according to any one of claims 1 to 4, wherein the reaction time when chemically modifying with the reactive gas is 3 hours or less.
The method for producing a chemically modified cellulose nonwoven fabric according to any one of claims 1 to 5, wherein the chemically modified cellulose nonwoven fabric obtained has a chemical modification rate of 5 to 65 mol%.
A chemically modified cellulose nonwoven fabric produced by the production method according to any one of claims 1 to 6.
A cellulose fiber resin composite material comprising the chemically modified cellulose nonwoven fabric according to claim 7 and a resin.
After chemically modifying cellulose in a cellulose nonwoven fabric of cellulose fibers having a number average fiber diameter of 2 to 400 nm using a reactive gas,
A method for producing a cellulose fiber resin composite material, wherein a chemically modified cellulose nonwoven fabric and a resin are combined.