JP2022072702A - Method for Producing Cellulose Fiber Composite and Cellulose Fiber Composite Composition - Google Patents

Abstract

To provide a method for producing a cellulose fiber composite that enables production of a cellulose fiber composite from which water, an excessive dispersant and a vinyl-based homopolymer are simply removed with low energy, without hindering dispersibility to a dispersed material of a resin such as a cellulose fiber, and a method for producing a cellulose fiber composite composition using the cellulose fiber composite.SOLUTION: A method for producing a cellulose fiber composite includes: a step of preparing a copolymer obtained by grafting a vinyl-based polymer with a cellulose derivative as a dispersant, and preparing a dispersion liquid obtained by dispersing a cellulose fiber in an organic solvent or a mixed solvent of an organic solvent and water, by the dispersant; and a step of separating a liquid containing a vinyl-based homopolymer not grafted with an excessive dispersant and/or cellulose derivative not absorbed to the cellulose fiber, from the dispersion liquid, and thereby collecting the cellulose fiber adsorbed with the dispersant as a target cellulose fiber composite.SELECTED DRAWING: None

Description

The present invention relates to each method for producing a cellulose fiber composite and a cellulose fiber composite composition, and in particular, a method for producing a cellulose fiber composite in which a dispersant is adsorbed on the cellulose fiber and recovered as the cellulose fiber composite, and the method thereof is used. The present invention relates to a method for producing a cellulose fiber composite composition in which cellulose fibers are dispersed in a resin or the like.

Cellulose is used as a renewable resource for various purposes such as paper and functional materials. In addition, so-called nanocellulose, which is obtained by defibrating cellulose at the nano level, is attracting attention as a material with new functions.
Nanocellulose is a cellulose nanofiber (CNF) with a fiber diameter of 10 nm or less (called TEMPO oxide CNF or phosphate esterified CNF, also called a single nanofiber) by chemical treatment, mechanical and physical defibration. CNF, which has a larger fiber diameter than the chemical treatment by, microcellulose, cellulose nanocrystal (CNC), which is obtained by treating pulp with strong acid, etc. Are known.
These materials are film materials, gas barrier materials, viscosity modifiers, lubricants, heat conductive materials, plant growth agents, thermosetting resins, radiation curable resins such as UV and electron beams, composite materials with general-purpose resins, and composites with rubber. Its application is widely expected as a material.

A promising use of nanocellulose is compounding with resin. Nanocellulose has strength close to that of carbon fiber and aramid fiber, is one-fifth the weight of steel, and is more than five times stronger. Therefore, the composite material in which nanocellulose is dispersed in a resin has high strength and light weight, and is expected to be applied to automobile members such as exterior materials, interior materials and rubber belts.

Various approaches have been taken to disperse and complex nanocellulose in resins. For example, a method of mixing pulp with a resin and, if necessary, a swelling agent and defibrating using a kneader, or a single nano-sized CNF dispersion solution having a diameter of less than 10 nm is mixed with the resin in the same manner. It is a method of defibrating using a kneader.

However, with these methods, it is difficult to disperse at the single nano level, and it is difficult to obtain the desired physical properties.
One of the reasons is that many nanocelluloses have hydrophilic functional groups on their surface, so that they have excellent affinity and dispersibility in water, but generally dispersibility in highly hydrophobic resins. Is extremely bad. In particular, CNF produced by the TEMPO oxidation method or the phosphoric acid esterification method is useful because it has a fiber diameter of a single nano level, but it is hydrophobic because it has a carboxylic acid base or a phosphoric acid base on the surface. Very poor compatibility with resin.

Therefore, various technical studies have been made to disperse it in the resin.
One of them is a method of introducing a hydrophobic functional group by a chemical reaction using a hydroxyl group or the like existing on the surface of nanocellulose.
For example, grafting of caprolactone (see Patent Document 1), acetylation by addition reaction of acetic anhydride (see Patent Document 2), addition reaction of alkenyl succinic anhydride and the like are known (see Patent Document 3).
Further, there is also known a method of using an acrylic block polymer having an affinity for both components of nanocellulose and a resin in which the resin is desired to be dispersed as a dispersant (see Patent Documents 4 and 5).
In addition, the applicant of the present application has prepared a cellulose fiber dispersion composite capable of dispersing cellulose fibers, particularly nanocellulose in an organic solvent, a resin, or the like at an inexpensive and sufficient level, and a cellulose fiber composition containing the cellulose derivative. We have proposed a complex having a structure in which a vinyl-based polymer is grafted onto a cellulosic polymer (this complex is referred to as a "dispersant" in the present invention), and a cellulosic fiber composition containing the complex and a cellulosic fiber. (See Patent Document 6). Specific examples of the cellulose fiber composition include those containing an organic solvent, a resin precursor, a resin, and the like.

Japanese Unexamined Patent Publication No. 2011-68707 JP-A-2017-165946 Japanese Patent No. 5757779 Japanese Unexamined Patent Publication No. 2016-104865 International Publication No. 2015/152188 Japanese Unexamined Patent Publication No. 2020-7525

In the technique described in Patent Document 6, cellulose fibers, particularly nanocellulose, can be dispersed in a resin at an inexpensive and sufficient level. However, when producing a dispersant having a structure in which a vinyl-based polymer is grafted on a cellulose derivative, a vinyl-based homopolymer that has not been grafted on the cellulose derivative is also produced as a by-product, and such a vinyl-based homopolymer can be obtained. It may adversely affect the physical properties of the cellulose fiber composition. Also, it is not efficient to include an excess dispersant that does not contribute to the dispersion of the cellulose fibers. Patent Document 6 does not disclose a method for removing this vinyl-based homopolymer or an excess dispersant. Further, as a method for removing water, dehydration is performed under reduced pressure, but if water can be removed with lower energy, the value of the technique will be further enhanced.

Therefore, the present invention relates to the improved technique of the invention described in Patent Document 6, and does not impair the dispersibility of cellulose fibers in a material to be dispersed such as a resin, and water, an excess dispersant, a vinyl-based homopolymer, etc. It is an object of the present invention to provide a method for producing a cellulose fiber composite capable of easily producing a cellulose fiber composite removed with low energy, and a method for producing a cellulose fiber composite composition using the cellulose fiber composite. There is.

As a result of diligent studies, the present inventor has found that the above problems can be solved by adopting the following configuration.

That is, in the method for producing a cellulose fiber composite of the present invention, a copolymer obtained by grafting a vinyl polymer on a cellulose derivative is used as a dispersant, and the dispersant is used in an organic solvent or a mixed solvent of an organic solvent and water. By the step of preparing a dispersion liquid in which cellulose fibers are dispersed and by separating the liquid containing an excess dispersant that is not adsorbed by the cellulose fibers and / or a vinyl-based homopolymer that is not grafted on the cellulosic derivative from the dispersion liquid. , Includes a step of recovering the cellulose fibers adsorbed by the dispersant as a target cellulose fiber composite.

Further, in the method for producing a cellulose fiber composite composition of the present invention, after the cellulose fiber composite is produced by the above method, the cellulose fiber composite is combined with an organic solvent, a resin and / or a resin precursor as a material to be dispersed. It comprises the step of redispersing the cellulose fibers in the material to be dispersed by mixing.

In addition, regarding the terms in the present invention, if the terms are arranged just in case, the cellulose fibers recovered from the dispersion liquid to which the dispersant is adsorbed are referred to as "cellulose fiber composite", whereas this "cellulose fiber" is used. A product in which cellulose fibers are (re) dispersed in a material to be dispersed (organic solvent, resin, resin precursor, etc.) using a "composite" is referred to as a "cellulose fiber composite composition".

According to the present invention, an advantage in the technique described in Patent Document 6, that is, since the cellulose fibers can be sufficiently dispersed in a resin or the like, it is effective for producing a composite material (composite composition) of the cellulose fibers and the resin. Further, grafting a vinyl polymer to a cellulosic derivative has an advantage that it can be carried out at a relatively low cost. In addition, water, vinyl homopolymers that do not contribute to dispersibility, and excess dispersant are removed easily and with low energy, and a necessary and sufficient amount of dispersant is adsorbed on the cellulosic fibers. Since it remains, it is expected that the dispersion of the cellulose fibers in the resin will be more efficient in the compounding with the resin and the like, and the effect of improving the physical properties of the resin and the like will be further improved.

Hereinafter, preferred embodiments of the method for producing a cellulose fiber composite and a cellulose fiber composite composition according to the present invention will be described in detail, but the scope of the present invention is not limited to these explanations, and other than the following examples. However, changes may be made as appropriate without impairing the gist of the present invention.

[Dispersant]
The dispersant used in the present invention has a structure in which a vinyl-based polymer is grafted on a cellulose derivative. As such a dispersant, for example, those disclosed as "complex for dispersing cellulose fibers" in JP-A-2020-7525 can be used.

The cellulose derivative is one in which a part of the hydroxyl group of cellulose is substituted.
As the cellulose derivative, a conventionally known cellulose derivative can be used, and specifically, for example, methyl cellulose, ethyl cellulose, butyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, carboxymethyl cellulose, cellulose acetate, cellulose acetate. Butyrate, cellulose acetate propionate, triacetyl cellulose, nitro cellulose, cationized cellulose and the like can be mentioned.
Of these, ethyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, triacetyl cellulose, and cationized cellulose are preferable from the viewpoints of high solubility in organic solvents, ease of grafting vinyl polymers, and availability.

These conventionally known cellulose derivatives usually have unmodified hydroxyl groups. This hydroxyl group can be used to introduce a polymerizable unsaturated group or a thiol (mercapto) group. By introducing a polymerizable unsaturated group or a thiol group in this way, it is possible to easily graft a vinyl-based polymer, which will be described later, using these functional groups as a starting point.
The introduction of the polymerizable unsaturated group or thiol group is carried out, for example, by addition-reacting an isocyanate-based (meth) acrylate compound such as Karenz MOI or AOI manufactured by Showa Denko with the above-mentioned conventionally known cellulose derivative. ) Addition reaction of anhydrides such as acrylic acid and maleic anhydride, addition reaction of (meth) acrylic acid using a condensing agent such as carbodiimide, (meth) acrylic acid chloride, organic acid having a thiol group It can be carried out by reacting with or the like. Examples of organic acids having a polymerizable unsaturated double bond or a thiol group include (meth) acrylic acid, maleic acid, crotonic acid, butentricarboxylic acid, 4-ethenylbenzoic acid, 3-mercaptopropionic acid and the like. Be done.
In addition, in this specification, the notation of "(meth) acrylic acid" is a notation including both methacrylic acid and acrylic acid. The same applies to notations such as "(meth) acrylate".

In the introduction of the polymerizable unsaturated group and the thiol group, various solvents and catalysts (condensing agents, organic metal materials, amines, etc.) can be used as in the known technique.
Further, it is desirable that the number of polymerizable unsaturated groups and thiol groups introduced is 20 or less on average per molecule of the cellulose derivative. Introducing more than 20 may result in gelation during graft polymerization.
Examples of the above reaction solvent include aprotic solvents such as ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and pyridine. Can be used alone or in combination.

In the present invention, the cellulose derivative may have a cationic group.
Since the cellulose derivative has a cationic group, it becomes a dispersant having excellent dispersibility of CNF produced by the TEMPO oxidation method or the phosphoric acid treatment method. These CNFs have carboxylic acid bases and phosphate bases on their surfaces, because the affinity between the functional groups on the surface of these CNFs and the cationic groups of the cellulose derivatives promotes the dispersion of CNFs. ..

As the cellulose derivative having a cation group, conventionally known cationized cellulose may be used, but the cation group can also be introduced into the cellulose derivative having no cation group as follows.
That is, for example, as a method for introducing an amino group, a method of reacting with thionyl chloride / ammonia and a method of reacting with ammonia or a polyvalent amino compound after introducing an epoxy group are known. Further, a method of introducing a compound having both an amino group and a carboxyl group in the molecule by reacting them with the above-mentioned condensing agent or the like can be carried out.
Examples of the above reaction solvent include aprotic solvents such as ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and pyridine. Can be used alone or in combination.
The average number of cationic groups per molecule of the cellulose derivative is preferably in the range of 1 to 30.

The graft of the vinyl-based polymer to the cellulose derivative can be carried out, for example, by radically polymerizing the vinyl-based monomer in the presence of the cellulose derivative into which the polymerizable unsaturated group or the thiol group has been introduced as described above. .. A graft chain, which is a vinyl-based polymer, is formed with a polymerizable unsaturated group or a thiol group as a base point.

In the above, examples of the vinyl-based monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl (meth) acrylate, 2 -Alkyl group such as ethylhexyl (meth) acrylate (meth) acrylate with 1 to 20 carbon atoms, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glyceryl (meth) acrylate, dimethylaminoethyl (Meta) acrylate, diethylaminoethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl ( Meta) acrylate, dicyclopentenyloxyethyl (meth) acrylate adamantyl-based (meth) acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd .: MADA, MDMA, EtADA, EAMA (P), etc.), methoxypolyethylene with 1 to 30 repeating units Glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate with 1 to 30 repeating units, butoxydiethylene glycol (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloy Loxyethyl succinic acid, glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethylmethacrylate, 2- (meth) acryloxyethyl acid phosphate, styrene, styrene derivative, (meth) acrylic acid, (meth) acrylamide, N -Phenylmaleimide, N-cyclohexylmaleimide, maleic anhydride, (meth) acrylonitrile, N-vinylpyrrolidone, silicone-based (meth) acrylate (manufactured by JNC, trade names Silaplane "FM-0711", "FM-0721", " FM-0725 ", etc., manufactured by Shin-Etsu Chemical Co., Ltd .:" X-22-174DX "," X-22-2426 "," X-22-2475 ", etc.)), fluorine substituent-containing (meth) acrylate (manufactured by Daikin Co., Ltd.) (Various fluorine-substituted alkyl (meth) acrylates, etc.) and the like.

It is also possible to use polyfunctional (meth) acrylates such as ethylene glycol di (meth) acrylate and hexanediol di (meth) acrylate, divinylbenzene and the like in an amount that does not insolubilize in the solvent by gelation. .. In addition, each of these monomers can be used alone or in combination of two or more.

The combination of the vinyl-based monomers described above changes the properties of the vinyl-based polymer produced, and in particular, the dispersion performance of the cellulose fibers in the organic solvent or resin. As a general theory, the Solubility Parameter (SP) value can be mentioned as an index of affinity with the organic solvent or resin to be dispersed. It is desirable to design the grafted vinyl polymer so that the SP value of the dispersion target is close to the SP value. In particular, it is desirable that the difference between the experimental value and the SP value on the calculated value is within 1.0 ((cal / cm ³ ) ^1/2 ).
Further, as the vinyl-based monomer, a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate and a polyalkylene oxide-based monomer component, particularly, methoxypolyethylene glycol (meth) acrylate having 1 to 30 repeating units, and the number of repeating units. When methoxypolypropylene glycol (meth) acrylate having a value of 1 to 30 is used, an effective interaction effect can be expected even when an acid base or the like is present in the cellulose fiber, so that it can be used as one component to be copolymerized. desirable.

Furthermore, it is also desirable to select a vinyl-based monomer that has an interaction with the material to be dispersed (particularly resin). Examples of the interaction include a hydrophobic interaction such as an alkyl group, a hydrogen bond such as a hydroxyl group, an amine, a carboxyl group and an amide group, and a conjugated system stack such as π-π due to an aromatic ring. It can be realized by using what you have.
Furthermore, it is also possible to introduce a reactive group into the produced vinyl-based polymer to form a bond with the resin or the like to be dispersed. One method is to copolymerize a vinyl-based monomer having an epoxy group such as the above-mentioned glycidyl (meth) acrylate or 3,4-epoxycyclohexylmethyl (meth) acrylate. Another method is to introduce a (meth) acrylate group, a vinyl group, an allyl group or the like which can be polymerized using a functional group, for example, a hydroxyl group or a carboxyl group in the generated vinyl polymer by a chemical reaction. .. For the introduction of such reactive groups, isocyanate group-containing (meth) acrylates such as Karenz MO-I and AO-I (manufactured by Showa Denko), glycidyl (meth) acrylate, and 3,4-epoxycyclohexylmethyl (meth). This can be achieved by an addition reaction using acrylate or the like.

In the polymerization of the cellulose derivative introduced with the polymerizable unsaturated group or the thiol group and the vinyl-based monomer, it is preferable that each of them is blended in the range of 5:95 to 99: 1 by weight. If it is out of this range, the effect of the cellulose fiber as a dispersant may be lowered.
In the above-mentioned polymerization, it is not necessary that all the vinyl-based polymers formed from the vinyl-based monomers are grafted (chemically bonded) to the cellulose derivative. A polymer produced by homopolymerization of a vinyl-based monomer may be contained.

The molecular weight of the vinyl polymer formed by grafting on the cellulose derivative is preferably selected from the range of 1000 to 500,000 in terms of weight average molecular weight. If the weight average molecular weight is less than 1000, the effect as a dispersant may be lowered, and if the weight average molecular weight exceeds 500,000, the viscosity tends to be too high.
The weight average molecular weights of the cellulose derivative, the vinyl-based polymer grafted on the cellulose derivative, and the dispersant (copolymer in which the vinyl-based polymer is grafted on the cellulose derivative) are determined by gel permeation chromatography (GPC). It is a standard polystyrene conversion value according to.

The molecular weight of the dispersant is preferably in the range of 5,000 to 800,000 in terms of weight average molecular weight. This weight average molecular weight is assumed to include a vinyl-based polymer bonded to a cellulose derivative and a bonded or non-bonded vinyl-based homopolymer (homopolymer).
The molecular weight of the dispersant measured by the GPC method may be due to the solution characteristics peculiar to the cellulose derivative, but may not be simply the sum of the cellulose derivative and the vinyl polymer. Although the details are unknown, the binding of the vinyl polymer to the cellulose derivative may change the spread of the polymer chain and the interaction between the cellulose derivatives. Therefore, it is only the measured molecular weight by the GPC method.

Examples of the organic solvent that can be used for polymerization include ethyl acetate, butyl acetate, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, benzyl alcohol, and dimethyl. Formamide, dimethylacetamide, N-methylpyrrolidone, ethyllactate, dimethylsulfoxide, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate (butyl carbitol acetate) ), Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol ethylmethyl ether, diethylene glycol isopropylmethyl ether, diethylene glycol diethyl ether, diethylene glycol butylmethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, Triethylene glycol butylmethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol dimethyl ether, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monobutyl ether, One or a mixture of dipropylene glycol dibutyl ether, tripropylene glycol dimethyl ether, dihydroterpineol acetate, tarpineol, dihydroterpineol, dihydroterpineol acetate and the like is preferred.

As the polymerization initiator, for example, various types of peroxide-based and azo-based radical polymerization initiators can be used. Further, the concentration at the time of polymerization, the concentration of the initiator and the like can be carried out within the range of known techniques.

After polymerizing the vinyl-based monomer on the cellulose derivative, it is also possible to carry out precipitation purification with a poor solvent if necessary, as in the case of conventional polymer purification. It is possible to remove unreacted monomers and by-products.
On the other hand, in the dispersant prepared by the above method, in addition to the ideal dispersant structure in which the cellulose derivative and the vinyl-based polymer are bonded, a non-bonded vinyl-based homopolymer is produced, which is produced. It is mixed. This is unavoidable due to the mechanism of radical chain transfer called radical polymerization. It was also found that it is difficult to completely remove the vinyl homopolymer from the produced polymer by reprecipitation purification or the like. It was also found that when such a vinyl-based homopolymer is contained in a large amount, it becomes a factor of deterioration of physical properties when the subsequent composite material is produced. Therefore, this production method also aims to effectively remove such vinyl-based homopolymers.

[Cellulose fiber]
The cellulose fiber used in the present invention is, for example, a cellulose nanofiber (CNF) (TEMPO oxide CNF or phosphoric acid esterified CNF) having a fiber diameter of 10 nm or less by chemical treatment as described above, and is a single nano. CNF, which has a larger fiber diameter than chemical treatment by mechanical and physical defibration), lignocellulose bound with lignin, its nanocellulose, microfibrils, and pulp are treated with strong acid to make it crystalline. Cellulose nanocrystals (CNC) from which the high part has been taken out, as well as bacterial cellulose produced by microorganisms.
Commercially available products include slurry CNF (phosphorylated product, name: Auro Visco) manufactured by Oji Holdings, powder CNF, TEMPO oxidation method CNF manufactured by Nippon Paper Industries, and Nanoforest-S manufactured by Chuetsu Pulp. , Water-dispersed CNF (name: ELLEX-S) manufactured by Daio Paper Corporation, water-dispersed CNF (name: Leocrysta) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. by the TEMPO oxidation method, and the like have a fiber diameter of 4 nm to 500 nm.
In the production method of the present invention, nanocellulose in which these fiber diameters are dispersed in water at the micrometer to nanometer level may be used, and mechanical and physical after adding the above-mentioned dispersant to the raw material pulp. It may be defibrated by a conventional method.

[Preparation of dispersion]
The method for producing a cellulose fiber composite of the present invention includes a step of preparing a dispersion liquid in which the cellulose fibers are dispersed by the dispersant in an organic solvent or a mixed solvent of the organic solvent and water.
As the cellulose fiber, as described above, the chemically treated cellulose fiber is commercially available in the form of an aqueous dispersion, and can also be produced from raw material pulp. Taking these as raw materials as an example, the dispersion can be prepared, for example, as follows.

First, when an aqueous dispersion of chemically treated cellulose fibers is used as a starting material, an organic solvent that dissolves in water is mixed with the chemically treated cellulose, which is an aqueous dispersion, and the above-mentioned dispersant is added. A dispersion can be prepared by stirring and mixing.
The amount ratio of the organic solvent to be mixed with respect to the water dispersion of cellulose fibers dispersed in water is preferably 1 to 50 parts by weight with respect to 1 part by weight of the water dispersion. The amount of the dispersant to be added should be in the range of 0.1 to 10 parts by weight of the dispersant (corresponding to the polymer solid content) with respect to 1 part by weight of the cellulose fiber in the aqueous dispersion of cellulose fibers. Is desirable. Generally, the solid content concentration of the chemically treated cellulose fiber (water-dispersed state) is in the range of 0.5% by weight to 5% by weight, and the amount of the dispersant is adjusted in the above range with respect to the solid content weight. Can be done.
In the dispersion operation, the mixture can be dispersed with cellulose fibers using a mechanical stirrer such as a homogenizer, a jet mill, a ball mill or a bead mill.

In the above process using an aqueous dispersion of cellulose fibers as a starting material, a specific organic solvent is mixed with the aqueous dispersion of cellulose fibers in advance to remove the mixture of water and the organic solvent, so that the majority of the components are contained. It is also desirable and feasible to remove the water from the solvent (preliminary dehydration).
As the organic solvent used for pre-dehydration, an amphoteric organic solvent having a high affinity with water is suitable for removing water, and methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, acetone, methyl ethyl ketone, tetrahydrofuran, Dioxane, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, ethyllactate, dimethylsulfooxide, ethyleneglycol monoacetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate and the like are preferably mentioned, and one or more thereof. Can be used in combination with seeds.
By carrying out this process, it may be possible to prevent the dispersant from insolubilizing due to the influence of water. That is, it is also possible to use a plurality of organic solvents and perform dehydration and removal of excess dispersant in a multi-step process.

When pulp fiber is used as a starting material, the pulp is mixed with a dispersant and an organic solvent alone or a mixed solvent of water and an organic solvent, and the pulp is defibrated by a mechanical or physical method to obtain nano. Can be distributed to levels. In this manufacturing method, the surface area increases as the pulp fiber is defibrated (the fiber diameter becomes smaller). Therefore, when a dispersant is added to the defibration step, the dispersant is adsorbed on the surface of the produced cellulose fiber, which is stable. A dispersed state can be formed. On the other hand, it is also possible to carry out the defibration step without adding the dispersant, and to proceed with the defibration by adding the dispersant in the final step.
Various types of pulp such as chemical pulp, mechanical pulp, chemical mechanical pulp, and semi-chemical pulp are used depending on the raw materials such as softwood, broadleaf, kenaf, and bamboo, depending on the treatment method. can do.
The above-mentioned organic solvent or a mixed solvent of water and an organic solvent is mixed with 1 part by weight of the cellulose fiber before defibration, for example, in the range of 0.5 to 100 parts by weight, and mechanical or physical means. The fiber can be defibrated at. The amount of the dispersant to be added is the same as when the aqueous dispersion of chemically treated cellulose fibers is used as a starting material.
For defibration, a jet crusher such as a kneader, a continuous twin-screw kneader, or a jet mill can be used in addition to the above-mentioned mechanical disperser.

In the above process using pulp fiber as a starting material, a mixture of an organic solvent and water, and if necessary, a dispersant are added to defibrate the cellulose fiber such as pulp, and then gradually to the organic solvent. It is also possible to replace, wash and remove water and excess dispersant.

As the organic solvent used in this step, the organic solvent used for the introduction of the functional group or the graft polymerization may be used at the time of producing the dispersant, but in particular, the amphipathic organic solvent as exemplified for the pre-dehydration is used. It can be preferably used.

As described above, by dispersing the cellulose fibers with the dispersant in the organic solvent or the mixed solvent of the organic solvent and water, the dispersant is adsorbed on the surface of the cellulose fibers.

[Recovery of cellulose fiber composite]
The method for producing a cellulosic fiber composite of the present invention is a liquid containing, from the dispersion prepared in the above step, an excess dispersant not adsorbed on the cellulosic fibers and / or a vinyl homopolymer not grafted on the cellulosic derivative. By separating the above, the cellulose fibers on which the dispersant is adsorbed are recovered as the target cellulose fiber composite.

In the dispersion liquid after the above-mentioned dispersion liquid preparation step, the cellulose fibers are dispersed in the organic solvent or the mixed solvent of the organic solvent and water. By separating the liquid from this dispersion by this step, it is possible to recover the cellulose fiber composite having an ideal structure in which a necessary and sufficient amount of the dispersant is adsorbed on the cellulose fibers. In other words, components that may affect the deterioration of physical properties, such as dispersants that do not adsorb to cellulosic fibers and vinyl-based homopolymers, are separated and removed. Since water can also be removed as a liquid component, it is possible to simultaneously remove unnecessary components such as vinyl-based homopolymers that may affect the removal of water and the deterioration of physical properties.
As a method for separating the liquid, a filtration method using various filters, a method of pouring out and removing the liquid from the state where the cellulose fiber and the liquid are separated, a method of precipitating and separating the cellulose fiber by a centrifuge or the like, etc. Is feasible. In particular, it is desirable to carry out a filtration method because it is simple and low cost.
The filters used in this operation include various paper filters, their processed filters, resin filters made of fibrous or porous bodies such as fluororesins, nylon, polypropylene, polyether sulfone, and cellulose mixed esters, and MERK. Membrane filters such as Millipore manufactured by the company, resin mesh filters, metal mesh filters, glass fiber filters, tubular extraneous filtration filters, etc. are used. The pore diameter of the opening can be in the range of 10 nm to 50 μm. Alternatively, there is a retained particle size as an index of filter performance, and it is preferable that this value is in the range of 50 nm to 20 μm. Further, a plurality of types of filters having different performance differences may be used in combination.
The solution temperature at the time of filtration or separation from the liquid is usually carried out in the range of −10 ° C. to 100 ° C. Further, when the filtration method is carried out, it is possible to perform depressurization (suction) filtration or pressurization filtration.

In the liquid separation step, it is also desirable to wash the cellulose fiber composite with an organic solvent. This cleaning step makes it possible to effectively remove water and vinyl-based homopolymers in the dispersant. In particular, repeated washing can reduce the amount of water contained and the like to 1.0% by weight or less. By reducing the amount of water contained to 1.0% by weight or less, excellent effects can be expected in terms of characteristics such as physical properties when applied to a cellulose fiber composite composition or the like described later.
On the other hand, the desirable amount of the dispersant adsorbed on the cellulose fiber is preferably in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the cellulose fiber. Depending on the diameter of the cellulose fiber, the smaller it is, the larger the surface area and the more adsorbed amount, but as a result of examining various fiber diameters, it was found that the desired range is as described above. It was found that if the dispersant is adsorbed in this range, the cellulose fibers can be uniformly dispersed in various materials to be dispersed. If it is less than 1 part by weight, the dispersibility of the cellulose fiber is lowered, and if it is more than 200 parts by weight, the physical properties of the composite when the cellulose fiber is composited with a resin or the like may be lowered. There is.
The organic solvent used in this washing step is not particularly limited, but an amphipathic organic solvent as exemplified for pre-dehydration can be preferably used.

The liquid separation step does not mean that the liquid component is completely separated from the solid component, and the cellulose fiber composite to be recovered is in a wet state in which a part of the organic solvent is taken into the cellulose fiber and remains. May be there. On the contrary, the organic solvent may be almost completely removed, but if the organic solvent is completely removed, aggregation between the cellulose fibers may occur. Therefore, the preferable range of the remaining organic solvent is 1 to 200 parts by weight with respect to 1 part by weight of the cellulose fiber adsorbed by the dispersant.
Further, it is desirable from the viewpoint of cost that the organic solvent used in the above-mentioned dehydration treatment, adsorption of the dispersant and removal of the excess dispersant is repeatedly used by recovering and purifying the organic solvent.

[Cellulose fiber composite composition]
By mixing the cellulose fiber composite (cellulose fiber on which the dispersant is adsorbed) obtained as described above with the material to be dispersed (organic solvent, resin, resin precursor, etc.), the cellulose fiber becomes uniform in the material to be dispersed. It is possible to prepare a cellulose fiber composite composition dispersed in.
The cellulose fiber composite composition will be described below.
As a specific configuration, various configurations may be adopted depending on the intended use and the like. Hereinafter, the first to third configurations will be exemplified as preferable configurations.

<First composition: Organic solvent dispersion composition>
The first composition of the composition is an organic solvent dispersion composition containing the cellulose fiber composite and an organic solvent.
As the organic solvent, those used in the above-mentioned reaction, polymerization or dispersion process can be used, and examples thereof include the following.
Ethyl acetate, butyl acetate, tetrahydrofuran, dioxane, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, butyl alcohol, benzyl alcohol, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethyllactate, dimethylsulfoxide, ethylene glycol monoethyl ether, ethylene Glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate (butyl carbitol acetate), diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol Ethyl Methyl Ether, Diethylene Glycol Isopropyl Methyl Ether, Diethylene Glycol Diethyl Ether, Diethylene Glycol Butyl Methyl Ether, Diethylene Glycol Dibutyl Ether, Triethylene Glycol Dimethyl Ether, Triethylene Glycol Butyl Methyl Ether, Propylene Glycol Monomethyl Ether, Propylene Glycol Monoethyl Ether, Propylene Glycol Monomethyl Ether Acetate , Propylene Glycol Diethyl Ether, Propylene Glycol Diacetate, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Dimethyl Ether, Dipropylene Glycol Monobutyl Ether, Dipropylene Glycol Dibutyl Ether, Tripropylene Glycol Diethyl Ether, Dihydro Tarpineol Acetate, Tarpineol, Dihydro Tarpineol, Dihydro Tarpineol Acetate Is one or a mixture such as.

The organic solvent is preferably in the range of 5 to 500 parts by weight with respect to 1 part by weight of the cellulose fiber composite.
An organic solvent dispersion composition can be obtained by mixing the above-mentioned cellulose fiber composite with the above-mentioned organic solvent according to the intended use and redispersing the cellulose fibers using the above-mentioned dispersion device or the like.
The cellulose fiber composite as a raw material may contain the organic solvent used in the above-mentioned manufacturing process. It is also preferable to remove the organic solvent contained in these cellulose fiber composites by a vacuum desolving method or the like.
The composition having the first configuration described above can be widely applied as an ink, an adhesive, a compounding material, a raw material for various parts, and the like.

<Second composition: resin precursor dispersion composition>
The second composition of the composition is a composition containing the cellulose fiber composite and a resin precursor.
The composition according to the second composition can also be prepared by the same method as the composition according to the first composition. That is, it is a method in which the cellulose fiber composite and the resin precursor are mixed, the dispersion treatment as described above is carried out, and the organic solvent present in the cellulose fiber composite is removed as needed.

Here, the resin precursor forms a polymer material by a polymerization reaction or the like, and is a (meth) acrylate compound, a vinyl compound, an allyl compound, an acid anhydride, an amine compound, an isocyanate compound, or the like. Epoxy compounds, reactive silicone compounds and the like can be used.

Among these, (meth) acrylate compounds, vinyl compounds, isocyanate compounds and epoxy compounds are particularly preferably used because of their high reactivity and versatility.
Examples of the (meth) acrylate compound include bifunctional (meth) acrylate compounds such as alkyl compounds having 1 to 30 carbon atoms, methoxyethylene oxide compounds, bisphenol A skeleton compounds, and aromatic (meth) acrylate compounds. Di (meth) acrylate compounds such as ethylene glycol, propylene glycol, bisphenol A skeleton, fluorene skeleton, and tricyclodecane skeleton as (meth) acrylate compounds can be used as more polyfunctional (meth) acrylate compounds. Glycerin skeletal (meth) acrylate compound, (mono-, di-, tri-) trimethylolpropane skeletal system, isocyanurate skeletal polyfunctional (meth) acrylate compound, (mono-, di-, tri-) pentaerythritol skeletal Examples thereof include polyfunctional (meth) acrylate compounds such as system polyfunctional (meth) acrylate compounds.

Examples of the vinyl compound include divinylbenzene, styrene, styrene derivatives, vinylnaphthalene, acrylonitrile and the like.

Examples of the isocyanate-based compound include isocyanates typified by hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI), and polyisocyanates such as additives between them and alcohols.

Examples of the epoxy compound include bisphenol A-based, bisphenol F-based, bisphenol S, novolak phenol-based, resolphenol-based, naphthalene-based, biphenyl-based, and hydrogenated compounds thereof, isocyanurate-based, polybutadiene-based glycidyl having a skeleton. Examples thereof include polyfunctional epoxy compounds such as ether type, glycidylamide type, glycidyl ester type and alicyclic epoxy type, and monofunctional epoxy compounds which are reactive diluents.

As the reactive silicone compound, for example, various RTV silicone rubbers manufactured by Shin-Etsu Chemical Co., Ltd. and silicones for LIM (Liquid Injection Molding) can be used. Not limited to this, various RTV silicone rubbers such as two-component condensation type, addition type, and UV curable type, and silicone materials for LIM can be used.

The blending ratio of the cellulose fiber composite and the resin precursor is preferably in the range of 5 times to 100 times the weight of the cellulose fiber composite. When a (meth) acrylate compound is used, it is also possible to add a polymerization inhibitor such as hydroquinone for the purpose of improving storage stability, as in the prior art.
Further, when the cellulose fiber composite contains an organic solvent, it can be removed by heating or performing a vacuum desolvation process using a known device, if necessary.

The composition having the second constitution can be widely applied as a UV curing material, a 3D modeling material, a thermosetting material, an adhesive, a compounding material, a raw material for various parts, and the like.

<Third composition: resin dispersion composition>
The third composition of the composition is a composition containing the cellulose fiber composite and a resin.
As the resin, various acrylic resins, polystyrene, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, various polycarbonates, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, nitrile rubber, butadiene rubber, poly (styrene-butadiene) , Polyisoprene, ethylene-propylene-diene rubber, various polyesters, various polyurethanes, various nylon resins (polyamides), polyvinyl acetals such as polyacetal and polyvinyl butyral, cellulose resins such as ethyl cellulose, cellulose acetate butyrate and cellulose acetate, polyphenylene oxide, Examples thereof include polyphenylene sulfide, phenol resin, silicone resin, and fluororesin.

As a method for producing the composition according to the third configuration, for example, the cellulose fiber composite described above and the resin described above are mixed and heated as necessary using a kneader, a continuous twin-screw kneader, or the like. It is a method of mechanically kneading and dispersing. Further, from the above-mentioned resins, those having solubility in an organic solvent are selected, dissolved, and the above-mentioned cellulose fiber composite is mixed and stirred therein, and then the organic solvent is uniformly dispersed. The method of removing is also preferably applicable.
It is preferable to use these methods properly depending on the type of resin used.

The blending ratio of the cellulose fiber composite and the resin is preferably in the range of 5 times to 100 times the weight of the resin with respect to 1 part by weight of the cellulose fiber composite.

The third composition can also be used as a raw material for various purposes as an amorphous substance or an amorphous substance containing various organic solvents. Further, it can be applied to various parts and the like as a bulk-like, film-like, spherical or fibrous structure formed from itself by heat molding, machining or the like. Further, it can be applied as a film shape formed by coating or melt molding or as a form laminated on another film substrate.

<Arbitrary component in the composition of the present invention>
In addition to the above-mentioned dispersant, cellulose fiber, organic solvent, resin precursor and resin, various kinds of various materials may be blended in the above-mentioned composition of the present invention.
Examples include surfactants, plasticizers, viscosity modifiers, defoaming agents, leveling agents, stabilizers such as UV absorbers and antioxidants, dyes, polymer particles, inorganic particles such as metal particles and ceramic particles. , Epoxy curing agents, curing acceleration catalysts, polymerization initiators, acid anhydrides that can react with epoxy compounds and isocyanate compounds, polyfunctional alcohols, polyfunctional amines, and the like. These materials can be blended in the range of, for example, 0.001 to 90% by weight based on the total weight of the composition.

Hereinafter, examples and comparative examples of the method for producing the cellulose fiber composite and the cellulose fiber composite composition according to the present invention are shown. However, the present invention is not limited to these examples.

[Synthesis of dispersant]
<Synthesis Example 1: Dispersant A>
100 parts by weight of ethyl cellulose (“Etocell STD-10” manufactured by Dow Chemical Co., Ltd., number average molecular weight: 227,000) and 300 parts by weight of ethyl acetate were added to the reaction vessel and mixed, and ethyl cellulose was uniformly dissolved in ethyl acetate. A solution was prepared.
In the above solution, methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.): 1.14 parts by weight, diisopropylcarbodiimide as a condensing agent (manufactured by Wako Pure Chemical Industries, Ltd.): 1.66 parts by weight, and dimethylamino as a reaction accelerator. Pyridine (manufactured by Wako Pure Chemical Industries, Ltd.): 0.08 parts by weight was added and mixed. Subsequently, the reaction was carried out with stirring at 40 ° C. for 12 hours, and a methacrylate group was introduced into a part of the hydroxyl group of ethyl cellulose by an ester bond (the number of introduced methacrylate groups is 3 on average per ethyl cellulose chain). The introduction of the functional group was confirmed by FT-IR spectroscopy, and it was confirmed that an ester bond was formed.
The temperature of the above reaction solution was raised to 50 ° C., nitrogen was blown into the solution in a bubble shape by a glass tube, and nitrogen substitution was performed while stirring. Further, benzyl methacrylate: 20 parts by weight was mixed as a vinyl-based monomer, and azoisobutyronitrile (AIBN) (manufactured by Wako Pure Chemical Industries, Ltd.): 0.4 parts by weight was further added as a polymerization initiator, and the temperature was 80 ° C. The polymerization reaction was carried out for 8 hours. The concentration of the polymer component in the solution after the reaction was 29% by weight.
When a part of the produced polymer was purified and subjected to GPC molecular weight analysis and composition analysis by ¹ H-NMR, a polymer having almost the same composition as the above-mentioned charged composition of ethyl cellulose and benzyl methacrylate was produced, and this was used as a dispersant. Used as.

<Synthesis Example 2: Dispersant B>
100 parts by weight of ethyl cellulose (“Etocell STD-20” manufactured by Dow Chemical Co., Ltd., number average molecular weight: 39,000) and 300 parts by weight of ethyl acetate were added to the reaction vessel and mixed, and ethyl cellulose was uniformly dissolved in ethyl acetate. A solution was prepared.
To the above solution, 1.1 parts by weight of methacrylic acid, 1.62 parts by weight of diisopropylcarbodiimide as a condensing agent, and 0.08 parts by weight of dimethylaminopyridine as a reaction accelerator were added and mixed. Subsequently, the reaction was carried out with stirring at 40 ° C. for 12 hours, and a methacrylate group was introduced into a part of the hydroxyl group of ethyl cellulose by an ester bond (the number of introduced methacrylate groups is 5 on average per ethyl cellulose chain). The introduction of the functional group was confirmed by FT-IR spectroscopy, and it was confirmed that an ester bond was formed.
The temperature of the above reaction solution was raised to 50 ° C., nitrogen was blown into the solution in a bubble shape by a glass tube, and nitrogen substitution was performed while stirring. Further, butyl methacrylate: 50 parts by weight was mixed as a vinyl-based monomer, 0.5 part by weight of azoisobutyronitrile (AIBN) was further added as a polymerization initiator, and a polymerization reaction was carried out at 80 ° C. for 8 hours. The concentration of the polymer component in the solution after the reaction was 33% by weight.
When a part of the produced polymer was purified and subjected to GPC molecular weight analysis and composition analysis by ¹ H-NMR, a polymer having almost the same composition as the above-mentioned charged composition of ethyl cellulose and butyl methacrylate was produced, and this was used as a dispersant. Used as.

<Synthesis Example 3: Dispersant C>
100 parts by weight of ethyl cellulose (“Etocell STD-10” manufactured by Dow Chemical Co., Ltd., number average molecular weight: 227,000) and 300 parts by weight of ethyl acetate were added to the reaction vessel and mixed, and ethyl cellulose was uniformly dissolved in ethyl acetate. A solution was prepared.
To the above solution, 1.14 parts by weight of methacrylic acid, 1.66 parts by weight of diisopropylcarbodiimide as a condensing agent, and 0.08 parts by weight of dimethylaminopyridine (manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction accelerator were added. , Mixed. Subsequently, the reaction was carried out with stirring at 40 ° C. for 12 hours, and a methacrylate group was introduced into a part of the hydroxyl group of ethyl cellulose by an ester bond (the number of introduced methacrylate groups is 3 on average per ethyl cellulose chain). The introduction of the functional group was confirmed by FT-IR spectroscopy, and it was confirmed that an ester bond was formed.
The temperature of the above reaction solution was raised to 50 ° C., nitrogen was blown into the solution in a bubble shape by a glass tube, and nitrogen substitution was performed while stirring. Further, dicyclopentanyl methacrylate (manufactured by Hitachi Chemical Co., Ltd.): 50 parts by weight was mixed as a vinyl-based monomer, and azoisobutyronitrile (AIBN): 0.4 parts by weight was further added as a polymerization initiator, and the temperature was 80 ° C. The polymerization reaction was carried out for 8 hours. The concentration of the polymer component in the solution after the reaction was about 27% by weight.
When a part of the produced polymer was purified and subjected to GPC molecular weight analysis and composition analysis by ¹ H-NMR, a polymer having almost the same composition as the above-mentioned charged composition of ethyl cellulose and dicyclopentanyl methacrylate was produced. Was used as a dispersant.

<Synthesis Example 4: Dispersant D>
100 parts by weight of ethyl cellulose (“Etocell STD-4” manufactured by Dow Chemical Co., Ltd., number average molecular weight: 137,000) and 300 parts by weight of ethyl acetate were added to the reaction vessel and mixed to uniformly dissolve ethyl cellulose in ethyl acetate. A solution was prepared.
To the above solution, add 3-mercaptopropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.): 2.32 parts by weight, diisopropylcarbodiimide as a condensing agent: 2.76 parts by weight, and dimethylaminopyridine 0.13 parts by weight as a reaction accelerator. , Mixed. Subsequently, the reaction was carried out with stirring at 40 ° C. for 12 hours, and thiol groups were introduced into some of the hydroxyl groups of ethyl cellulose by an ester bond (the number of introduced thiol groups was 3 on average per ethyl cellulose chain). The introduction of the functional group was confirmed by FT-IR spectroscopy, and it was confirmed that an ester bond was formed.
The temperature of the above reaction solution was raised to 50 ° C., nitrogen was blown into the solution in a bubble shape by a glass tube, and nitrogen substitution was performed while stirring. Further, 10 parts by weight of isobornyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a vinyl-based monomer was mixed, and 0.4 part by weight of azoisobutyronitrile (AIBN) was further added as a polymerization initiator, and 8 at 80 ° C. A time polymerization reaction was carried out. The concentration of the polymer component in the solution after the reaction was 27% by weight.
When a part of the produced polymer was purified and subjected to GPC molecular weight analysis and composition analysis by ¹ H-NMR, a polymer having almost the same composition as the above-mentioned charged composition of ethyl cellulose and isobornyl methacrylate was produced. Used as a dispersant.

<Synthesis Example 5: Dispersant E>
100 parts by weight of ethyl cellulose (“Etocell STD-20” manufactured by Dow Chemical Co., Ltd., number average molecular weight: 39,000) and 300 parts by weight of ethyl acetate were added to the reaction vessel and mixed, and ethyl cellulose was uniformly dissolved in ethyl acetate. A solution was prepared.
To the above solution, 1.36 parts by weight of 3-mercaptopropionic acid, 1.62 parts by weight of diisopropylcarbodiimide as a condensing agent, and 0.08 parts by weight of dimethylaminopyridine as a reaction accelerator were added and mixed. Subsequently, the reaction was carried out with stirring at 40 ° C. for 12 hours, and thiol groups were introduced into some of the hydroxyl groups of ethyl cellulose by an ester bond (the number of introduced thiol groups was 5 on average per ethyl cellulose chain). The introduction of the functional group was confirmed by FT-IR spectroscopy, and it was confirmed that an ester bond was formed.
The temperature of the above reaction solution was raised to 50 ° C., nitrogen was blown into the solution in a bubble shape by a glass tube, and nitrogen substitution was performed while stirring. Further, 20 parts by weight of dicyclopentanyl methacrylate as a vinyl-based monomer was mixed, 0.4 part by weight of azoisobutyronitrile (AIBN) was further added as a polymerization initiator, and a polymerization reaction was carried out at 80 ° C. for 8 hours. .. The concentration of the polymer component in the solution after the reaction was 29% by weight.
When a part of the produced polymer was purified and subjected to GPC molecular weight analysis and composition analysis by ¹ H-NMR, a polymer having almost the same composition as the above-mentioned charged composition of ethyl cellulose and dicyclopentanyl methacrylate was produced. Was used as a dispersant.

[Preliminary dehydration and solvent replacement of cellulose fiber aqueous dispersion]
<Preliminary dehydration example 1>
50 parts by weight of TEMPO oxidation method CNF (CNF solid content 2 wt% aqueous dispersion: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and propylene glycol monomethyl ether (PGME): 1000 parts by weight as an amphoteric organic solvent were put into a glass container. Stirring and mixing were performed for 30 minutes using a high-speed stirrer.
After that, No. A mixture of CNF and PGME was obtained by suction filtration using No. 2 filter paper (holding particle diameter> 5 μm) and repeated washing with PGME: 500 parts by weight. The weight of the mixture was about 73.5 g.
It was confirmed that there was no non-volatile content in the filtrate after the above operation. By measuring the non-volatile content of the sediment, the CNF content in the sediment can be determined. The CNF content in the sediment actually taken out was 1.36% by weight. The water content contained was 1.0% by weight or less.

<Preliminary dehydration example 2>
50 parts by weight of TEMPO oxidation method CNF (CNF solid content 2 wt% aqueous dispersion: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and 1000 parts by weight of ethylene glycol monomethyl ether (EGME) as an amphoteric organic solvent were put into a glass container. Stirring and mixing were performed for 30 minutes using a high-speed stirrer.
After that, No. A mixture consisting of CNF and EGME was obtained by suction filtration using the filter paper No. 2 and repeated washing with EGME. The weight of the mixture was about 75 g.
It was confirmed that there was no non-volatile content in the filtrate after the above operation. By measuring the non-volatile content of the sediment, the CNF content in the sediment can be determined. The CNF content in the sediment actually taken out was 1.33% by weight. The water content contained was 1.0% by weight or less.

<Preliminary dehydration example 3>
50 parts by weight of TEMPO oxidation method CNF (CNF solid content 2 wt% aqueous dispersion: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and 1000 parts by weight of dimethylformamide (DMF) as an amphoteric organic solvent are put into a glass container, and a high-speed stirrer is used. Was stirred and mixed for 30 minutes.
After that, No. A mixture consisting of CNF and DMF was obtained by suction filtration using the filter paper No. 2 and repeated washing with DMF. The weight of the mixture was about 70 g.
It was confirmed that there was no non-volatile content in the filtrate after the above operation. By measuring the non-volatile content of the sediment, the CNF content in the sediment can be determined. The CNF content in the sediment actually taken out was 1.43% by weight. The water content contained was 1.0% by weight or less.

[Preparation of cellulose fiber composite]
By the following process, the dispersant prepared in the above synthesis example is adsorbed on the surface of the water-dispersed TEMPO oxide CNF to prepare a composite of CNF and the dispersant capable of uniformly dispersing CNF in the hydrophobic medium. bottom.
<Example 1>
The mixture of CNF and PGME obtained in the operation of Preliminary Dehydration Example 1 was weighed in a glass container so as to be 20 parts by weight (the weight of CNF contained was about 0.27 parts by weight), and further, in Synthesis Example 1. The prepared ethyl acetate solution containing the dispersant A was mixed so as to be 0.94 parts by weight (0.27 parts by weight of the solid content of the dispersant) and ethylene glycol dimethyl ether (EGDME): 100 parts by weight, and a high-speed stirrer was used. Was stirred and mixed for 30 minutes using the above to obtain a dispersion liquid in which the dispersant was adsorbed on CNF.
Further, the above dispersion liquid was changed to No. Suction filtration was performed at room temperature (25 ° C.) using 2 filter papers (holding particle diameter> 5 μm), and further washing was performed with 100 parts by weight of EGDME: CNF (CNF) in which the dispersant was adsorbed as a filtration product on the filter paper. Cellulose fiber composite) was obtained.
By measuring the non-volatile content of the filtration product on the filter paper and the filtrate after suction filtration, the amount of the organic solvent in the filtration product and the amount of the dispersant adsorbed on the CNF can be determined. As a result, it was found that about 95% by weight of the organic solvent (EGDME) was contained in the filtration product, and about 42 parts by weight of the dispersant was adsorbed with respect to 100 parts by weight of CNF. Since the amount of the added dispersant is 100 parts by weight with respect to 100 parts by weight of CNF, about 42% by weight of the added dispersant is adsorbed. In addition, when the dispersant in the filtrate that was not adsorbed by CNF was analyzed by ¹ H _- NMR, the acrylic polymer component (homoromer of benzyl methacrylate) was found to be increased compared to the composition of the initial dispersant. found. That is, it was found that the grafted body of ethyl cellulose having the structure of the target dispersant and the acrylic polymer was preferentially adsorbed on the CNF.
Moreover, when the water content in the product was measured, it was 0.5% by weight or less. Also in the following Examples 2 to 17, the water content in the product was 0.5% by weight or less.
(In the above-mentioned composite of CNF and the dispersant, the ethylene glycol dimethyl ether used for the preparation may be used in a residual state or may be removed.)

<Examples 2 to 5>
Using the dispersants B to E shown in Synthesis Examples 2 to 5 as the dispersant, a cellulose fiber composite was prepared under the same amount of organic solvent as in Example 1 and the weight ratio of CNF and the dispersant. .. These conditions are shown in Table 1.

<Examples 6 to 7>
In Example 1, the amount of the dispersant added was increased. The conditions are as shown in Table 1.

<Example 8>
A mixture of CNF and EGME obtained in the operation of Pre-dehydration Example 2 was used. Other conditions are the same as in Example 1.

<Example 9>
A mixture of CNF and EGME obtained in the operation of Pre-dehydration Example 2 was used. Other conditions are the same as in Example 5.

<Example 10>
A mixture of CNF and DMF obtained in the operation of Pre-dehydration Example 3 was used. Other conditions are the same as in Example 1.

<Example 11>
A mixture of CNF and DMF obtained in the operation of Pre-dehydration Example 3 was used. Other conditions are the same as in Example 5.

<Example 12>
In the treatment of adsorbing the dispersant in Example 1, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 13>
In the treatment of adsorbing the dispersant in Example 5, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 14>
In the treatment of adsorbing the dispersant in Example 8, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 15>
In the treatment of adsorbing the dispersant in Example 9, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 16>
In the treatment of adsorbing the dispersant in Example 10, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 17>
In the treatment of adsorbing the dispersant in Example 11, isopropyl alcohol (IPA) was used instead of EGDME as the organic solvent used.

<Example 18>
The dispersant was adsorbed at the same time as the dehydration treatment without pre-dehydration as follows.
10 parts by weight of TEMPO oxidation method CNF (CNF solid content 2% by weight aqueous dispersion: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in a glass container, PGME: 100 parts by weight, EGDME: 100 parts by weight was added, and stirring and mixing were performed for 30 minutes using a high-speed stirrer. Further, the ethyl acetate solution containing the dispersant A prepared in Synthesis Example 1 was added in an amount of 0.69 parts by weight (the solid content weight of the dispersant was equal to the amount of CNF), and the mixture was similarly stirred at high speed.
After that, No. By suction filtration using No. 2 filter paper and further washing with EGDME: 200 parts by weight, a CNF (cellulose fiber composite) in which a dispersant was adsorbed as a filtration product on the filter paper was obtained.
By measuring the non-volatile content of the filtration product on the filter paper and the filtrate after suction filtration, the amount of the organic solvent in the filtration product and the amount of the dispersant adsorbed on the CNF can be determined. As a result, it was found that about 55% by weight of the organic solvent (EGDME) was contained in the filtration product, and about 45 parts by weight of the dispersant was adsorbed with respect to 100 parts by weight of CNF. Since the amount of the added dispersant is 100 parts by weight with respect to 100 parts by weight of CNF, about 45% by weight of the added dispersant is adsorbed.
The water content in the product was 0.5% by weight or less. Also in Examples 19 to 22 below, the water content in the product was 0.5% by weight or less.

<Examples 19 to 22>
Using the dispersants B to E shown in Synthesis Examples 2 to 5 as the dispersant, a cellulose fiber composite was prepared under the same amount of organic solvent as in Example 18 and the weight ratio of CNF and the dispersant. .. These conditions are shown in Table 1.

[Preparation of Cellulose Fiber Composite Composition]
Using the cellulose fiber composite (including an organic solvent) prepared in Examples 1 to 22, the CNF content thereof is weighed as 2 parts by weight, A-TMPT: 98 parts by weight is mixed therein, and a high-speed stirrer is used. CNF was dispersed using. Then, the organic solvent contained was removed using the vacuum solvent removal apparatus. Further, 9 parts by weight of Irgacure TPO: 9 parts by weight was mixed as a photoinitiator.
By the above operation, a cellulose fiber composite composition (resin precursor dispersion) in which cellulose fibers are redispersed in a polyfunctional acrylic monomer (A-TMPT: trimethylolpropane triacrylate: manufactured by Shin-Nakamura Chemical Co., Ltd.) which is a resin precursor. Composition) was obtained.

[Evaluation of Cellulose Fiber Composite Composition]
The cellulose fiber composite composition obtained above is coated on a release-treated polyethylene terephthalate film using a blade coater, cured by a UV irradiation device of a high-pressure mercury light source with an integrated energy light amount of 1000 mJ, and peeled from the release film. A transparent film having a thickness of about 100 μm was obtained. Various properties of the obtained cellulose fiber-dispersed resin film were evaluated.

<Dispersity>
The dispersed state of the cellulose fibers (CNF) in the film was evaluated by observing with a microscope or a polarizing microscope.
As an evaluation criterion of dispersibility, the dispersion state of CNF under polarization was evaluated at 500 times optical. The level at which no aggregates were confirmed was marked with ◯, the level with a small number of agglomerates was marked with Δ, and the level with a large number of agglomerates was marked with ×. These results are also shown in Table 1 in correspondence with each Example number of the cellulose fiber composite as a raw material.

<Film transparency>
The transparency of the film was visually evaluated.
The evaluation criteria were ○ for those that did not feel turbidity at all in the permeation state, and × for those with turbidity. These evaluation results are also shown in Table 1 in correspondence with each Example number of the cellulose fiber composite used as a raw material.

<Mechanical characteristics>
The tensile elastic modulus was measured by measuring the tensile strength of the film (SS curve) with a tensile tester (AG-10N) manufactured by Shimadzu Corporation. The tensile elastic modulus of the A-TMPT single film in which CNF is not dispersed is 1.6 GPa. Based on this, those with an improvement of 20% or more are: ○, those with less than 20% to equivalent: △, those with a decrease. : ×. These evaluation results are also shown in Table 1 in correspondence with each Example number of the cellulose fiber composite used as a raw material.

[Comparative experiment]
Hereinafter, comparative experiments were carried out to confirm the superiority of the present invention.
<Comparative Example 1>
In Example 18, an equal amount of dispersant was mixed with CNF, a resin precursor was mixed without filtering after dispersion, and water and an organic solvent were removed by a vacuum desolving device. It took a longer time to remove water and organic solvent than the filtration method. Further, a film sample for evaluation was prepared and evaluated in the same manner as described above. As a result, the dispersibility of CNF and the transparency of the film were good, but the mechanical properties were slightly inferior to those of the examples. It was presumed that the cause of the inferior mechanical properties was the influence of the vinyl homopolymer contained in the dispersant. The results are shown in Table 1.

<Comparative Example 2>
In Comparative Example 1, the same treatment was carried out except that the amount of the dispersant with respect to CNF was halved. Further, a film sample for evaluation was prepared and evaluated in the same manner as described above. As a result, it was found that the dispersibility of CNF was slightly inferior to that of the examples. In addition, the mechanical properties were slightly inferior to those of the examples. It was presumed that the cause of the inferior mechanical properties was the effect of the reduced dispersibility of the vinyl homopolymer and CNF contained in the dispersant. The results are shown in Table 1.

<Comparative Example 3>
In Comparative Example 1, the treatment was carried out without adding a dispersant. Further, a film sample for evaluation was prepared and evaluated in the same manner as described above. As a result, the dispersibility, transparency, and mechanical properties of CNF were all significantly inferior to those of the examples. This result shows the effect of the dispersant of the present invention. The results are shown in Table 1.

From the above Examples and Comparative Examples, the present invention improves the dispersibility of CNF in a resin or the like, and removes the vinyl homopolymer or the like contained in the dispersant to obtain a CNF-dispersed resin or the like. It was found that the physical properties of the composition could be improved. Furthermore, it has been clarified that the water contained in the CNF aqueous dispersion can be efficiently removed, which contributes to the cost reduction of the process.

Claims (3)

A step of preparing a dispersion liquid in which cellulose fibers are dispersed in an organic solvent or a mixed solvent of an organic solvent and water by using a copolymer obtained by grafting a vinyl polymer on a cellulose derivative as a dispersant.
By separating a liquid containing an excess dispersant that is not adsorbed on the cellulose fibers and / or a vinyl homopolymer that is not grafted on the cellulosic derivative from the dispersion liquid, the cellulosic fiber on which the dispersant is adsorbed is the target cellulosic fiber composite. A method for producing a cellulose fiber composite, which comprises a step of collecting the cellulose fiber composite. The method for producing a cellulose fiber composite according to claim 1, which comprises a step of washing the dispersant with an amphipathic organic solvent. After producing the cellulose fiber composite by the method according to claim 1 or 2, the cellulose fiber composite is mixed with an organic solvent, a resin and / or a resin precursor as a material to be dispersed to obtain a cellulose fiber. A method for producing a cellulose fiber composite composition, which comprises a step of redispersing the material to be dispersed.