JP7260318B2 - Cellulose fiber aqueous dispersion - Google Patents

Description

The present invention relates to a cellulose fiber aqueous dispersion.

Cellulose is a main component of plant cell walls, and plays a role in supporting plants by coexisting with lignin and hemicellulose. It is also the most abundantly produced and accumulated resource on earth, and its effective utilization is desired. Cellulose is used in various industrial fields, one of which is its use as a filler. A filler is a particle or fibrous substance added to resins, rubbers, paints, etc. for the purpose of improving strength and functionality and reducing costs.

In the development of polymeric materials (polymers), compounding with functional fillers is an important development factor, and the impact on the physical properties of composite materials varies greatly depending on the shape of the filler. In particular, needle-like and fibrous fillers have characteristics such as high mechanical and thermal reinforcing effects, high electrical conductivity, and damping properties.
In addition, amorphous or spherical fillers have characteristics such as easy workability, isotropy of physical properties, little adverse effect on toughness, and little deformation after molding.
Among the above, cellulose is a natural polymer in which glucose is linked by β-1,4-glycosidic bonds, and has a high aspect ratio and is promising as a fibrous filler.

As a fiber-reinforced resin, glass fiber is relatively inexpensive, easy to mold and drill, and has a high reinforcing effect, and is currently widely used in a wide range of fields. However, glass fiber has a density of 2.55 g/cm ³ and is heavy compared to resin, which is disadvantageous in applications requiring weight reduction.

Moreover, in recent years, commercialization of CFRP, which is a composite of carbon fibers, is progressing as an aircraft member. Carbon fiber (PAN-based) has a density of 1.82 g/cm ³ , and is lighter and stronger than glass fiber. .

However, the problem remains that the resin compounded with glass fiber or carbon fiber has poor recyclability and cannot be incinerated. For this reason, attempts have long been made to substitute fibers derived from natural products, such as cellulose, chitin and chitosan, which are relatively easy to obtain and environmentally friendly. Cellulose has a density of 1.5 g/ ^cm3 , is lighter than glass fiber and carbon fiber, and has relatively high rigidity. Resin is on the market. Moreover, unlike glass fiber and carbon fiber, it can be incinerated and has thermal recyclability. Furthermore, in recent years, research and development are underway to add nanofibers with a fiber diameter of 100 nm or less, which are called nanocellulose or cellulose nanofibers, to resins to produce a reinforcing effect.

By the way, cellulose is a natural product, and its fiber diameter is determined by plant species. Typical plant fibers have a fiber diameter of 20 to 50 μm. is very difficult.

For example, in Patent Document 1, cellulose having a fiber diameter of 20 μm or less is prepared as an additive for rubber or resin.
Patent Document 2 discloses a method for shortening the crystallization peak time and increasing the degree of crystallinity by adding cellulose fibers to an aliphatic polyester resin.
Patent Document 3 discloses that cellulose fibers are used as a dehydration aid, and that the cellulose fibers have a fiber diameter of 10 to 30 μm.
Patent Document 4 discloses, as a method for producing a resin containing cellulose fibers, a method of uniformly dispersing defibrated cellulose fibers in a resin without using an aqueous medium.
Patent Document 5 discloses a resin composition containing microcellulose fibers and a method for producing the same.

Japanese Patent No. 3867117 Japanese Patent No. 5592696 Japanese Patent No. 4260045 Japanese Patent No. 6005470 Japanese Patent No. 5675066

However, the cellulose described in the examples of Patent Document 1 is not fibrous but flat cellulose particles, and cellulose fibers in a fibrous shape have not been obtained.
The cellulose whose effect is found in Patent Document 2 is a flat cellulose fiber having an average diameter exceeding 20 μm.
The cellulose fiber obtained in Patent Document 3 is a hydrous material, and is premised on being used in water. That is, no mention is made of producing cellulose fibers having an average fiber diameter of 0.1 to 20 μm in a dry state.
In Patent Document 4, the dried cellulose fibers with an average fiber diameter of 0.1 to 20 μm cannot be obtained alone due to the manufacturing method, and it is necessary to disperse them in a solvent and perform a polymerization reaction. As a general filler, it cannot be added to thermoplastic resins or rubbers.
In Patent Document 5, the average fiber diameter of the cellulosic fibers specifically produced in Examples is less than 0.1 μm, and the production of cellulose fibers having an average fiber diameter of 0.1 to 20 μm in a dry state is described. has not been substantively mentioned.

As described above, in the prior art, there is no specific mention of obtaining cellulose fibers having an average fiber diameter of 0.1 to 20 μm in a dry state, and the dried cellulose fibers maintaining such a fiber shape are used as a resin. It is not known to exhibit excellent properties when compounded.

On the other hand, it is known that fine cellulose fibers having an average fiber diameter of 20 nm can be obtained by disentangling cellulose fibers with a water jet, a grinder, a high-pressure homogenizer, a bead mill, or the like. Also known is a technique for reducing the fiber diameter of cellulose to about 3 nm by using chemical treatment in combination. With these methods, it is possible to obtain nanofibers with a fiber diameter of 0.1 μm or less as an aqueous dispersion. During the removal process, cellulose forms a strong macrostructure due to hydrogen bonding. For this reason, cellulose fibers having an average fiber diameter of 0.1 μm or less have a strong agglomeration action during drying, and it is very difficult to obtain dried cellulose fibers in the state of unraveled fibers.

As described above, the present invention has been made in view of the above, and provides an aqueous cellulose fiber dispersion capable of producing a dry cellulose fiber dried body having an average fiber diameter of 0.1 μm or more and 20 μm or less. for the purpose.

The present inventors have made intensive studies to solve the above problems, and found that cellulose fibers having an average fiber diameter of 0.1 μm or more and 20 μm or less and having a hemicellulose content of 50% or less in the constituent sugar components of the cellulose fibers. The inventors have found that the problem can be solved by a cellulose fiber aqueous dispersion containing, and completed the present invention.

That is, the present invention is as follows.
[1] A cellulose fiber aqueous dispersion containing cellulose fibers, wherein the average fiber diameter of the cellulose fibers is 0.1 μm or more and 20 μm or less, and the proportion of hemicellulose in the constituent sugar components of the cellulose fibers is 50% or less. A cellulose fiber aqueous dispersion.
[2] The cellulose fiber aqueous dispersion according to [1], wherein the cellulose fibers have I-type cellulose crystals.
[3] The cellulose fiber aqueous dispersion according to [1] or [2], wherein the cellulose fiber has a viscosity average molecular weight of 100,000 or more.
[4] The cellulose fiber aqueous dispersion according to any one of [1] to [3], further comprising a surfactant.
[5] The cellulose fiber aqueous dispersion according to any one of [1] to [4], wherein the surfactant is at least one selected from the group consisting of stearic acid, oleic acid, glycerin, and polyglycerin derivatives.
[6] The cellulose fiber aqueous dispersion according to any one of [1] to [5], wherein the surfactant is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the cellulose fibers.

According to the present invention, it is possible to provide an aqueous cellulose fiber dispersion capable of producing a dry cellulose fiber dried body having an average fiber diameter of 0.1 μm or more and 20 μm or less.
The cellulose fiber dry body obtained from the cellulose fiber aqueous dispersion has high dispersibility when combined with a resin, and it is possible to obtain a resin composite having an excellent reinforcing effect.

[1. Cellulose fiber aqueous dispersion]
One embodiment (this embodiment) of the cellulose fiber aqueous dispersion of the present invention will be described in detail below.

This embodiment is a cellulose fiber aqueous dispersion containing cellulose fibers, wherein the average fiber diameter of the cellulose fibers is 0.1 μm or more and 20 μm or less, and the proportion of hemicellulose in the constituent sugar components of the cellulose fibers is 50% or less. It's becoming
Here, "aqueous" in the cellulose fiber aqueous dispersion means that the solvent or dispersion medium contains 50% by mass or more of water. A water dispersion in which the solvent or dispersion medium is composed only of water may be used, but various organic substances derived from additives or the like and capable of being dissolved in water may also be included.

In the present embodiment, the average fiber diameter of the cellulose fibers is 0.1 μm or more and 20 μm or less, and by using fibers having a larger fiber diameter than nanofibers (so-called cellulose nanofibers), the fiber shape maintainability is improved. can keep. That is, when dried, the retention of the fiber shape due to keratinization may deteriorate, but this can be suppressed in the present invention. In addition, it is possible to obtain a dried cellulose fiber that can greatly improve the tensile strength and tensile modulus when compounded with a resin. Further, when the proportion of hemicellulose in the constituent sugar components of the cellulose fibers is 50% or less, for example, cellulose fibers in an average fiber diameter of 0.1 μm or more and 20 μm or less can be satisfactorily obtained in a loose dry state.

If the average fiber diameter of the cellulose fibers is less than 0.1 μm, the problem of keratinization occurs. The average fiber diameter is preferably 0.5 μm or more, more preferably 1 μm or more. Also, the average fiber diameter is preferably 17 μm or less, more preferably 10 μm or less.
The average fiber diameter of cellulose fibers can be measured by the method described in Examples.

In a method that can obtain conventional nanofibers, for example, when controlling the average fiber diameter between 0.1 μm and 20 μm, it is possible to adjust the number of pulverizations, the pressure, and the number of rotations. If a cellulose raw material containing a large amount of is used, there will be a portion that is likely to become nanofibers and a portion that will be difficult to become nanofibers, resulting in a broad fiber diameter distribution. Therefore, in order to obtain an average fiber diameter of 0.1 μm or more and 20 μm or less, when the total amount of constituent sugars of cellulose fibers is taken as 100% by constituent sugar analysis, cellulose with a glucose ratio of 50% or more, that is, hemicellulose content is 50%. The following celluloses are preferred.

If the proportion of hemicellulose in the cellulose fibers exceeds 50%, the above-mentioned unraveled dry cellulose fibers cannot be obtained. The proportion of hemicellulose is preferably 35% or less, more preferably 30% or less, even more preferably 5% or less. It is also preferred that the proportion of hemicellulose is lower.
The hemicellulose ratio can be measured by the method described in Examples.

In addition, in order to make the ratio of hemicellulose in the cellulose fiber 50% or less, raw material cellulose having a low ratio of hemicellulose, for example, kraft pulp, cotton, or the like may be used. Moreover, depending on the raw material, the proportion of hemicellulose can be reduced to 50% or less by subjecting the cellulose fiber to a mercerization treatment in which the cellulose fiber is treated with an alkali.

Here, hemicellulose is a general term for polysaccharides other than cellulose contained in wood pulp and non-wood pulp. The main component of pulp is cellulose, and cellulose is a crystalline polysaccharide in which only glucose is linearly polymerized. On the other hand, hemicellulose is a branched polysaccharide containing monosaccharides such as xylose, mannose, arabinose, galactose, glucuronic acid and galacturonic acid. Hemicellulose is a low-molecular-weight, amorphous polysaccharide compared to cellulose. Polysaccharides such as xylan, arabinoxylan, mannan, glucomannan, and glucuronoxylan are known as typical hemicelluloses.

The cellulose fiber according to the present embodiment preferably has cellulose type I crystals. Cellulose type I crystals have a higher crystal elastic modulus than other crystal structures (cellulose II, III, and IV structures), and are therefore effective in obtaining a high elastic modulus, high strength, and a low coefficient of linear expansion.
The fact that the cellulose fiber has a type I crystal structure means that in the diffraction profile (wide-angle X-ray diffraction image) obtained by wide-angle X-ray diffraction image measurement, the scanning angle 2θ = 14 to 17° and 2θ = 22 to 23°. can be identified by having typical peaks at two positions of .

The viscosity-average molecular weight of the cellulose fibers is preferably 100,000 or more, more preferably 120,000 or more, and even more preferably 200,000 or more. When the viscosity-average molecular weight is 100,000 or more, excellent physical properties attributed to cellulose fibers can be brought out more favorably. Practically, the viscosity average molecular weight is preferably 300,000 or less.
The viscosity average molecular weight can be measured by the method described in Examples.

The cellulose fiber aqueous dispersion according to this embodiment preferably further contains a surfactant. By including a surfactant, the dispersibility of the cellulose fiber aqueous dispersion and the cellulose fiber dry body obtained by drying it can be improved.

Surfactants used in the present invention may be anionic surfactants, nonionic surfactants, and mixtures thereof that are soluble and dispersible in water and water-soluble alcohols such as ethanol and methanol. Specifically, stearic acid , oleic acid, glycerin, polyglycerin derivatives, and compounds thereof, but are not limited thereto.

Stearic acid is a saturated fatty acid most abundantly contained in animal and vegetable fats, and is widely distributed in nature as a fat and oil component. Examples of stearic acid include stearic acid, stearamide, aluminum stearate, magnesium stearate, sodium stearate, calcium stearate, barium stearate, PEG stearate, PEG-glyceryl stearate, PG stearate, and stearin. ascorbyl stearate, isocetyl stearate, glycol stearate, glyceride stearate, glyceryl stearate, cholesteryl stearate, diethanolamide stearate, diethylaminoethylamide stearate, ethyl stearate, vinyl stearate, sucrose stearate, sorbitan stearate, sodium stearate, bacyl stearate, butyl stearate, cetyl stearate, methyl stearate, hexyldecyl stearate, stearyl stearate, glycerol distearate, isohexadecyl stearate, glycerol monostearate, 12-hydroxystearate, 2-ethylhexyl stearate, glycerol monoisostearate, N,N'-ethylenebisstearic acid amide, stearate and the like.

Specific examples of oleic acid include oleic acid, oleic anhydride, ethyl oleate, butyl oleate, methyl oleate, oleyl oleate, sodium oleate, glycidyl oleate, copper(II) oleate, and cholesteryl oleate. , glycerol dioleate, glyceryl monooleate, oleate, butyl oleate, propyl oleate, dibutylammonium oleate, potassium oleate, ethyl oleate, N,N-diethanol oleamide, N,N -diethanol oleamide, 4-methylumbelliferyl oleate, trimethylolpropane trioleate, sodium sulfosuccinimidyl oleate, N,N'-ethylenebisoleamide, 5-bromo-4-oleate and chloro-3-indoxyl.

As glycerin, specifically, glycerin, diglycerin, PPG-9 diglyceryl, PPG-14 polyglyceryl-2 ether, diglycerin monocaprylate, POP (9) polyglyceryl ether, POP (14) polyglyceryl ether, POP (24 ) Polyglyceryl ether, POE (13) polyglyceryl ether, POE (20) polyglyceryl ether, POE (30) polyglyceryl ether, POE (40) polyglyceryl ether, polyglycerin, glycerin fatty acid ester, polyglyceryl monoisostearate, polyglyceryl diisostearate, monolauric acid Polyglyceryl, Decaglyceryl Monomyristate, Polyglyceryl Monooleate, Polyglyceryl Monostearate, Polyglyceryl Distearate, Polyglyceryl Condensed Ricinoleate, Diglyceryl Tetraisostearate, Polyglyceryl Pentaisostearate, Adipic Acid, Diethylene Glycol, Ethylhexylglycerin, Octoxyglycerin, Ozonated glycerin, cyclohexylglycerin, thioglycerin, bis-dioleoylglycerophosphoglycerin 2Na, hexylglycerin, polyglycerin-4, polyglycerin-6, polyglycerin-10, polyglycerin-20, polyglycerin fatty acid ester, diglycerin fatty acid esters, polyoxyethylene polyglyceryl ethers, glycerin fatty acid esters, monoglycerides, acetylated monoglycerides, organic acid monoglycerides, medium-chain fatty acid monoglycerides, polyglycerin fatty acid esters, sorbitan acid fatty acid esters, propylene glycol acid fatty acid esters, and the like.

Other glycerin esters include laurate, myristate, caprylate, behenate, erucate and condensed ricinoleate.

From the viewpoint of further improving dispersibility, the surfactant is preferably at least one selected from the group consisting of stearic acid, oleic acid, glycerin, and polyglycerin derivatives. Among them, polyglycerin derivatives are preferred, and polyglycerin condensed ricinoleic acid esters composed of polyglycerin and condensed ricinoleic acid are more preferred.

The amount of the surfactant is preferably 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of cellulose fibers (solid content). When it is 1 part by mass or more, the effect of suppressing aggregation of cellulose fibers is easily obtained, and when it is 30 parts by mass or less, it does not become an excessive amount with respect to cellulose fibers, and as a result, discoloration and poor drying are suppressed. be done.
The surfactant is more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Further, it is more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

The median diameter of the cellulose fibers in the cellulose fiber aqueous dispersion according to the present embodiment is preferably 10 μm or more, more preferably 15 μm or more, and 20 μm or more from the viewpoint of improving physical properties when compounded with a resin. is more preferable. From the viewpoint of maintaining good dispersibility, the particle size is preferably 80 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less. In addition, the median diameter is also a measure of the dispersibility of the cellulose fibers in the aqueous dispersion, and it can be said that good dispersibility is maintained by being within the above range.
The median diameter of the cellulose fibers in the cellulose fiber aqueous dispersion can be measured by the method described in Examples.

From the viewpoint of obtaining excellent productivity, the proportion (solid content concentration) of cellulose fibers in the cellulose fiber aqueous dispersion is preferably 0.1% by mass or more, more preferably 1% by mass or more, and 10% by mass or more. It is more preferably at least 15% by mass, and more preferably at least 15% by mass. Practically, the upper limit is about 30% by mass.
In general, the solid content concentration in a cellulose fiber aqueous dispersion is practically at most about 10% by mass, but the cellulose fiber aqueous dispersion of the present embodiment has good dispersibility, so the solid content concentration is relatively can be higher.

The cellulose fiber aqueous dispersion according to the present embodiment as described above can be produced, for example, from the following cellulose raw material through a mechanical treatment process or the like.

(raw material for cellulose)
The raw material cellulose used for producing the cellulose fiber aqueous dispersion preferably has cellulose type I crystals. Examples include woody (coniferous and hardwood), herbaceous, kraft pulp, cotton, ramie, algae, sea squirt, and bacterial cellulose. Among them, kraft pulp, cotton (cotton cellulose) and the like are preferable. As the constituent sugar of cellulose, one having a low hemicellulose content is preferred, and one having a high cellulose purity is preferred. Specifically, when the total amount of sugars detected by composition analysis is taken as 100%, it is preferable that the proportion of glucose in the constituent sugars is 50% or more. In other words, it is preferable that the proportion of hemicellulose in the constituent sugar components of the cellulose fiber is 50% or less. These cellulosic fibers may be used alone or in combination of two or more. Moreover, the shape of the cellulose-based raw material is preferably fibrous, powdery, chip-like, or flake-like from the viewpoint of ease of handling, and a mixture thereof may also be used.

(Mechanical processing process)
The mechanical treatment step is a step of fibrillating cellulose fibers having a fiber diameter of 20 to 50 μm so that the average fiber diameter is 0.1 to 20 μm. Fibrillation is a process of loosening fibers and further fluffing them. Preferably, the cellulose raw material is diluted and dispersed with water before the mechanical treatment to prepare a dispersion having a cellulose concentration of 0.1 to 30% by mass. 1 to 20% by mass is more preferable for fibrillation. In particular, when the content is 1 to 20% by mass, the efficiency of fibrillation becomes high, and an increase in viscosity can be suppressed.

In the mechanical treatment process, wet pulverization equipment can be used, including wet pulverization equipment, high-pressure homogenizers, ultra-high-pressure homogenizers, grinders (stone mill type pulverizers), high-speed defibrators, ball mills, bead mills, and discs. Mold refiners, conical refiners, twin-screw kneaders, vibration mills, homomixers, ultrasonic dispersers, beaters and the like.

As an apparatus capable of fibrillating while maintaining the fiber length, a wet pulverization apparatus is effective and preferable. Specifically, it is a method of defibrating by colliding against or mutually colliding hard bodies for collision by high-pressure injection treatment of 100 to 245 MPa through an injection nozzle with a diameter of 0.1 to 0.8 mm. This fibrillation method uses not only the shear force generated by passing the dispersion fluid through a narrow channel at high pressure and low speed, but also the impact caused by colliding with a hard body for collision or colliding with each other. Continuous defibration at high pressure using force or cavitation is possible. Further, one pass of the collision treatment is regarded as one pass, and in order to obtain uniform cellulose fibers, it is preferable to repeat the collision for preferably 1 to 30 passes, more preferably 1 to 20 passes.

In this step, the raw material cellulose fibers are preferably defibrated so that the fiber diameter is 0.1 μm or more and 20 μm or less. This prevents the fibrillated cellulose fibers from aggregating due to strong hydrogen bonds during drying. Although it is weakly aggregated in the drying process, it can be broken into fibers having an average fiber diameter of 0.1 μm or more and 20 μm or less by going through the dry pulverization process. That is, the average fiber diameter of the cellulose fibers in the cellulose fiber aqueous dispersion of the present embodiment can be maintained even in a dry state.

(Addition and mixing of surfactant)
In order to incorporate a surfactant into the cellulose fiber aqueous dispersion of the present embodiment, an anionic or nonionic surfactant that can be dissolved and dispersed in a water-soluble alcohol such as water, ethanol, or methanol is added to a mechanical treatment step. It is added to the cellulose fiber aqueous dispersion prepared above, and uniformly stirred and mixed with a commercially available propeller stirrer, blender, ribbon mixer, rotation-revolution type stirring deaerator, planetary mixer, or the like. It is also possible to add it before the mechanical processing step and to perform the wet grinding at the same time.

[2. Cellulose fiber dry body]
The cellulose fiber aqueous dispersion according to the present embodiment can be used as a cellulose fiber dry body by drying by a known drying treatment (drying process). From the viewpoint of further improving the dispersibility, a pulverizing step may be provided after the drying step.

The dried cellulose fiber material according to the present embodiment as described above is the dried material of the aqueous cellulose fiber dispersion according to the present embodiment, wherein the average fiber diameter of the cellulose fibers is 0.1 μm or more and 20 μm or less, and the cellulose fibers are It can be said that the dry cellulose fiber contains 50% or less of hemicellulose in the constituent sugar components. The dried cellulose fiber preferably has a water content of 10% by mass or less. For example, the water content can be reduced to 10% by mass or less by drying by the method described in the Examples.

(Drying process)
The drying method is not particularly limited, and drying may be performed using a commercially available drying device. For example, a spray drying device using a spray drying method, a drying device using a vacuum drying method, a flash drying device using a flash drying method, a hot air drying device using hot air, a steam drying device using steam, centrifugal force Spin drying equipment using vibration force, Vibration drying equipment using the force of vibration, Fluidized bed drying equipment using the fluidized bed drying method, Drum type drying equipment that attaches and dries on the surface of a rotating heating drum, Frozen slurry dispersion liquid A freeze-drying device for drying in a vacuum and the like are included.

(Pulverization process)
The pulverization step is not particularly limited, and may be pulverized using a commercially available pulverizer. For example, a table where the gravity and centrifugal force of the roller rotates, a roller mill that compresses and grinds by pressing against a bowl-shaped grinding container, compression of several atmospheres or more, high-pressure air or high-pressure gas is ejected, and the jet stream accelerates the raw material particles. A jet mill that pulverizes by the collision and impact action of the object, a hammer mill that pulverizes the supplied particles by impacting the supplied particles with a high-speed rotating hammer, and several dozen pins are attached to the surface of two discs facing each other and rotated at high speed. A pin mill that grinds, a rotating cylinder filled with grinding media that fills one-third of the volume around the horizontal axis, and a rotary mill that grinds the object by rotation, a cylindrical or trough-shaped mill Vibration mills that are filled with grinding media and vibrate the mill to cause the media to move and grind, planetary mills that grind with the impact force of a mechanism in which a container filled with grinding media rotates and revolves around the object. An attritor that uses 3 to 10 mm balls and a rod-shaped stirring arm to pulverize an object, a bead mill that fills a container with beads that act as a medium, and crushes the beads by colliding them with the rotation of an agitator. An air flow type pulverizer that pulverizes raw materials by causing them to face and collide with each other with an air flow generated by an impeller.

The dried cellulose fiber obtained as described above has an average fiber diameter of 0.1 μm or more and 20 μm or less and is in a dry state in which it is unraveled. Since it can exist in the resin while maintaining its dispersibility, desired properties such as strength and elastic modulus can be easily obtained.

[3. Cellulose fiber resin composite]
The cellulose fiber aqueous dispersion according to this embodiment can be applied to various moldings as a cellulose fiber-resin composite by compounding it with a resin in the state of the dispersion or in the form of a dried cellulose fiber. That is, the cellulose fiber-resin composite according to this embodiment can be said to be a cellulose fiber-resin composite obtained by combining the dried cellulose fiber according to this embodiment with a resin.

(Thermoplastic resin)
Examples of resins to be mixed include thermoplastic resins having a melting temperature of 300° C. or less. Specific examples include polyethylene, polypropylene, polystyrene, AS resin (acrylonitrile styrene), ABS resin, polyvinyl chloride, vinyl chloride resin, Acrylic resin, methacrylic resin, PET resin, polyethylene terephthalate, PVA resin, polyvinyl alcohol, polyvinylidene chloride, polyvinylidene fluoride, nylon 6, nylon 66, nylon 11, nylon 12, acetal resin, polyacetal, polycarbonate, PBT resin, polybutylene Terephthalate, polyphenylene sulfide, polyetherimide, polysulfone, polychlorotrifluoroethylene, fluororesin, polyamideimide, acetylcellulose, cellulose acetate, nitrocellulose, cellulose nitrate, cellulose propionate, ethyl cellulose, and the like. These thermoplastic resins can be used alone or in combination of two or more.

The content of the dry cellulose fiber in the cellulose fiber-resin composite according to the present embodiment is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, from the viewpoint of obtaining preferable physical properties, although it depends on the type of resin. is more preferred. Moreover, it is preferably 50% by mass or less, more preferably 40% by mass or less.
In addition, in the cellulose fiber resin composite according to the present embodiment, known additives (compatibilizer, heat stabilizer, antioxidant, etc.) can be mixed within a range that does not impair the effect.

To produce a cellulose fiber-resin composite, first, a dried cellulose fiber and a resin are mixed by a known method. After that, dry blending is preferably performed as pre-dispersion using a Henschel mixer, a blender, a stirrer such as a trimix, and a mixing device. After that, using various kneaders, the mixture is kneaded for a predetermined period of time while specifying the number of revolutions and the temperature to produce a cellulose fiber resin composite.

[4. Other configurations of cellulose fiber aqueous dispersion, cellulose fiber dry body, and cellulose fiber resin composite]
The resin used when using the cellulose fiber as a filler in the cellulose fiber aqueous dispersion or the cellulose fiber dry body is not limited to vinyl resins such as polyolefins, polycondensation resins such as polyamides, and the like, and has a melting point of 300°C. The following thermoplastic resins are applicable. In addition, it is possible to synthesize a new functional transparent film/resin by combining it with a transparent substrate (resin) such as epoxy having the same refractive index as cellulose. In particular, the cellulose fiber according to the present embodiment can change its strength or surface properties by forming a composite with a polymer such as phenolic resin, polyethylene glycol, polyethylene terephthalate, polyvinyl alcohol, etc., capable of forming hydrogen bonds.

Furthermore, the cellulose fiber according to the present embodiment can be combined with biodegradable resins such as polylactic acid, polybutylene succinate, and polycaprolactone to improve properties such as strength and heat resistance of these resins.

According to the present embodiment, by surface modification (chemical modification) of cellulose fibers, resins having properties other than those described above, such as cellulose fibers, are acetylated to give them hydrophobic properties, thereby making them hydrophobic such as acrylic resins. Compositing with resin is also possible.

In addition, it is possible to manufacture cosmetics (sunscreen agents) and liquid crystal substrates that take advantage of the optical properties of fine cellulose fibers, as well as filters that take advantage of nano-order voids generated between cellulose fibers. Separation/filtration materials with different properties and functions can be manufactured by substituting various functional groups for the hydroxyl groups of cellulose. Also, the size of the voids can be changed by controlling the diameter of the cellulose fibers. By making cellulose fibers into fine fibers, the specific surface area increases, making it suitable as an adsorbent. The film obtained by drying this is a porous membrane with pores controlled at the micro level. Available. When the cellulose fiber according to this embodiment is applied to the surface of an acoustic diaphragm such as a speaker, a uniform and hard film is formed, and similar effects can be obtained. In order to obtain excellent acoustic characteristics, a rigid material with high strength and high elastic modulus is required that allows the entire body to vibrate uniformly. Since the cellulose fiber according to this embodiment can be finely divided while maintaining high crystallinity, it can be used as a material for an acoustic diaphragm with a high elastic modulus.

In addition, by combining chitosan fiber, which is a cationic polymer derived from natural products, and cellulose fiber, which is an anionic polymer, it is expected that the electrostatic attraction will be reinforced by the charge of anions and cations, creating stronger composite fibers. is also possible. The most important factor affecting the strength of paper is the adhesive strength between fibers, which is determined by hydrogen bonding between hydroxyl groups of cellulose. Therefore, in order to increase the strength of paper, it is sufficient to increase hydrogen bonding, and it can be used as a paper strength enhancer.

In addition, the cellulose fibers according to the present embodiment can be carbonized by high-temperature treatment in the absence of oxygen (in an inert gas atmosphere such as nitrogen or argon). That is, biomass-derived carbon fibers can be produced. Porous carbon containing a large number of micro-level small pores is used as a deodorizing agent, a decolorizing agent, or a filter for water purification. It can be used for such fields. Porous carbon not only traps odors and dirt molecules in its small pores (pores), but can also trap ions (charged atoms and molecules) with the help of electricity. Capacitors with large capacities have been developed by utilizing the captured electric charge. In recent years, such capacitors have received a great deal of attention because they can be used as auxiliary power sources for fuel cell vehicles or as storages for storing surplus power at night. Since the capacitance of an electric double layer capacitor is determined by the amount of charge stored in the electric double layer, the larger the surface area of the electrode, the greater the capacitance that can be obtained. is used as an electrode material. In the present embodiment, the bio-carbon fiber obtained by carbonizing the naturally-derived fiber has a high specific surface area and is a mesoporous activated carbon with pores controlled at the nano level. It can be used as an electrode material that dramatically increases the

Moreover, the cellulose fiber according to the present embodiment can also be applied as a laundry detergent. Cellulose and cellulose derivatives have long been used in detergents as anti-soil redeposition agents. Anti-soil re-staining agents have the function of preventing soil components that have been detached from the laundry to adhere to clothes again due to the action of detergent surfactants, and are an important technology as water-saving washing machines become more popular. be. In the present embodiment, by converting cellulose into microfibers, the specific surface area is increased, and a more effective anti-redeposition effect than conventional cellulose materials can be expected. In addition, cellulose has a wide range of uses, and is expected to be used as a raw material for cosmetics, as a drug release carrier, as an additive to foods, as a coating agent for pharmaceutical preparations, as a heat insulating material, as a catalyst, and the like.

Although the above description assumes the cellulose according to the present embodiment, similar effects can be obtained with biomass-derived materials such as chitin, chitosan, silk, and carboxymethyl cellulose that have a fiber structure like cellulose.

EXAMPLES Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these.

Various measurements and observations in each example and comparative example were carried out as follows.
(Average fiber diameter of cellulose fibers in aqueous dispersion)
For fiber diameters of 1 μm or more, after sufficiently diluting and dispersing the aqueous dispersion so that each fiber is isolated, a preparation is prepared and examined with a microscope (manufactured by Keyence Corporation, device name: VHX-500). In observation, 50 fiber diameters of each fiber were observed, and the average value was taken as the average fiber diameter. For fiber diameters of less than 1 μm, after sufficiently diluting and dispersing the water dispersion so that the fibers are isolated one by one, it is dropped on the mica pieces, dried naturally, and then scanned with a scanning probe microscope (manufactured by Shimadzu Corporation). SPM-9700), 50 fiber diameters of each fiber were observed, and the average value was taken as the average fiber diameter.

(Constituent sugar analysis: percentage of hemicellulose)
Constituent sugar analysis was measured using a reducing sugar analysis system. In this method, after column separation, sugar reaction (Maillard reaction) is performed with boric acid and arginine at 150° C., and fluorescence is detected. The configuration of the reducing sugar analysis system is manufactured by Shimadzu Corporation, controller CBM-20A, liquid feed pump LC-20AD, autosampler SIL-20AC, column open CTO-20AC, fluorescence detector RF-20Axs, chemical reaction tank CRB. -6A was used. A sample containing water after fibrillation treatment was used. After drying by heating, 0.03 g of the sample was weighed and immersed in 300 μl of 70% sulfuric acid for 1 hour. 8.4 ml of pure water was added, heated at 110° C., and maintained under a reduced pressure environment for 60 minutes. After that, the sample is filtered through a glass fiber, and the volume is adjusted to 10 ml with pure water. Two volumes of a barium hydroxide solution with a concentration of 40% were added to one volume of the sample to salt out the sulfuric acid in the sample solution.

Then, it was subjected to analysis by filtering through a membrane filter with a pore size of 0.2 μm. Liquid chromatographic analysis was performed using columns: Asahipack NH2P-50 4E (250 mm L. x 4.6 mm id; S/NJ17T0192), and Asahipack NH2P-50G 4 (10 mm L. x 4.0 mm id; S/NP2810002 ) was used. Analysis was carried out with a mobile phase of acetonitrile/water/phosphoric acid=85/15/0.3 (v/v/v), a column temperature of 45° C., a flow rate of 0.8 ml/min, and an injection volume of 10 μl. As the detection conditions, a detector: RF-20Ax, a reaction solution of 5 g/L arginine, 0.4 mol/L boric acid, and a mixed aqueous solution of 0.2 mol/L potassium hydroxide were used. The reaction temperature was 150° C., the reaction coil was 2 m×0.5 mm, the detection wavelength was 320 nm excitation wavelength, and the fluorescence wavelength was 470 nm. The ratio (%) was examined. Then, the ratio of hemicellulose was determined from the total ratio (%) of detected amounts of rhamnose, xylose, arabinose, fructose and mannose, which are constituent sugars of hemicellulose.

(Confirmation of cellulose type I crystals)
The X-ray diffractometer (manufactured by Rigaku Co., Ltd., device name: rotating anticathode type X-ray generator Rotaflex RU-200B) was used to obtain CuKα rays (A = 1.542) passed through a Ni filter at an acceleration voltage of 40 kV and an acceleration current of 150 mA. was measured using a horizontal goniometer for powder X-ray diffraction manufactured by the same company. Diffraction intensity was measured over a range of diffraction angles 2θ from 5° to 35°. In the diffraction profile (wide-angle X-ray diffraction image) obtained by wide-angle X-ray diffraction image measurement of cellulose fibers, typical cellulose I The presence or absence of cellulose type I crystals was confirmed based on whether or not there was a peak attributed to type crystals.

(molecular weight measurement)
The molecular weight of cellulose fibers was measured using the viscosity method. Specifically, after obtaining a dry powder sample by freeze-drying the cellulose fiber aqueous dispersion, each cellulose fiber sample was dissolved in a copper ethylenediamine solution, and the relative viscosity of the solution to the solvent was measured using an Ostwald viscometer. The intrinsic viscosity was determined from the above, and the molecular weight (viscosity average molecular weight) of each cellulose fiber was calculated.

(Particle size distribution measurement)
The median diameter was measured in order to simply measure the degree of fiber defibration. The median diameter (the particle diameter at which the cumulative frequency is 50%) was determined by a laser diffraction/scattering particle size distribution measurement method (manufactured by Horiba Ltd., device name: LA-300).

(Determination of fiber shape after drying: observation with an electron microscope)
In order to confirm the shape of the dried cellulose fiber, the fiber appearance was confirmed using an electron microscope (manufactured by JEOL Ltd., device name: JCM-5700). Those in which each fiber is disassembled into fibrous form are A, those in which a plurality of fibers are not fibrous and aggregates are aggregated over the entirety of D, and in the middle, fibers It was judged as B when less than half of the particles were partially aggregated to form partial aggregates, and as C when more than half of the particles were partially aggregated. In addition, A and B judgment are made into a pass.

(Average fiber diameter after drying)
Fiber diameter measurement using an electron microscope (manufactured by JEOL Ltd., device name: JCM-5700) to measure the fiber diameter of the dried cellulose fiber for those whose fibrous bodies were confirmed in the fiber shape determination after drying. did 50 fiber diameters of each fiber were observed, and the average value was taken as the average fiber diameter. In addition, the fiber diameter could not be measured for those for which the fiber shape was not obtained in the determination of the fiber diameter.

[Example 1]
A cellulose fiber aqueous dispersion was prepared using commercially available kraft pulp as a raw material.
First, the pulp was pulverized in a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion of the obtained cotton powder-like cellulose was prepared with ion-exchanged water so as to have a concentration of 10% by mass, and defibrated for 3 times with a wet micronization device (manufactured by Sugino Machine Co., Ltd., device name: Starburst). It was carried out twice to loosen the fibers. After that, the proportion of hemicellulose in the constituent sugars of the cellulose fiber was measured by constituent sugar analysis. In addition, after freeze-drying the obtained cellulose fiber aqueous dispersion to obtain a dry powder sample, the average molecular weight was determined by the viscosity method, and the presence or absence of cellulose type I crystals was confirmed by X-ray diffraction measurement. rice field. Next, a condensed ricinoleic acid ester (product name: CRS-75, manufacturer: Sakamoto Yakuhin Kogyo Co., Ltd.) as a surfactant was added to the obtained 10% by mass aqueous dispersion of cellulose fibers in an amount of 10 parts by mass per 100 parts by mass of cellulose solid content. was added so as to be 1 part, and thoroughly stirred and mixed.
The average fiber diameter and particle size distribution of the cellulose fibers in the obtained cellulose fiber aqueous dispersion were measured. Table 1 shows the results.

After that, the dried cellulose fibers from which moisture was removed were obtained by heat-drying them at 80° C. for 4 hours while stirring. Further, the obtained dried cellulose was pulverized using a pin mill (manufactured by Nara Machinery Co., Ltd., device name: sample mill) to obtain cellulose fibers. An electron microscope was used to confirm whether the obtained cellulose fibers were fibrous, and the fiber shape after drying was determined. When fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Example 2]
A cellulose fiber aqueous dispersion was prepared using cotton derived from cotton as raw material cellulose. Cotton was pulverized with a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion of the obtained cotton powder-like cellulose was prepared with ion-exchanged water so as to have a concentration of 10% by mass, and defibration was performed for 10 times with a wet micronization device (manufactured by Sugino Machine Co., Ltd., device name: Starburst). It was carried out twice to loosen the fibers. Constituent sugar analysis, molecular weight measurement, and X-ray diffraction measurement were carried out in the same manner as in Example 1. Next, a condensed ricinoleic acid ester (product name: CRS-75, manufacturer: Sakamoto Yakuhin Kogyo Co., Ltd.) as a surfactant was added to the obtained 10% by mass aqueous dispersion of cellulose fibers in an amount of 10 parts by mass per 100 parts by mass of cellulose solid content. was added so as to be 1 part, and thoroughly stirred and mixed. Thereafter, in the same manner as in Example 1, the average fiber diameter and particle size distribution were measured. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Example 3]
A cellulose fiber aqueous dispersion was prepared using cotton derived from cotton as raw material cellulose. Cotton was pulverized with a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion of the obtained cotton powder-like cellulose was prepared with ion-exchanged water so as to have a concentration of 10% by mass, and fibrillation was performed twice using a wet micronization device (Starburst manufactured by Sugino Machine Co., Ltd.). loosened the fibers. Constituent sugar analysis, molecular weight measurement, and X-ray diffraction measurement were carried out in the same manner as in Example 1. Next, a condensed ricinoleic acid ester (product name: CRS-75, manufacturer: Sakamoto Yakuhin Kogyo Co., Ltd.) as a surfactant was added to the obtained 10% by mass aqueous dispersion of cellulose fibers in an amount of 10 parts by mass per 100 parts by mass of cellulose solid content. was added so as to be 1 part, and thoroughly stirred and mixed. Thereafter, in the same manner as in Example 1, the average fiber diameter and particle size distribution were measured. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Example 4]
A cellulose fiber aqueous dispersion was prepared using cotton derived from cotton as raw material cellulose. Cotton was pulverized with a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion of the obtained cotton powder-like cellulose was prepared with ion-exchanged water so as to have a concentration of 10% by mass, and fibrillation was performed 10 times using a wet atomization device (Starburst manufactured by Sugino Machine Co., Ltd.). loosened the fibers. Next, the obtained 10% by mass aqueous cellulose fiber dispersion (no surfactant) was subjected to constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution in the same manner as in Example 1. I made a measurement. Table 1 shows the results.
Further, a 10% by mass aqueous cellulose fiber dispersion was heat-dried at 80° C. for 4 hours with stirring to obtain a dried cellulose fiber from which moisture was removed. Further, the obtained dried cellulose was pulverized using a pin mill (manufactured by Nara Machinery Co., Ltd., device name: sample mill) to obtain cellulose fibers. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Example 5]
A cellulose fiber aqueous dispersion was prepared using cotton derived from cotton as raw material cellulose. First, cotton was pulverized in a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion of the obtained cotton powder-like cellulose was prepared with ion-exchanged water so as to have a concentration of 10% by mass, and fibrillation was performed 10 times using a wet atomization device (Starburst manufactured by Sugino Machine Co., Ltd.). loosened the fibers. Next, the obtained 10% by mass aqueous cellulose fiber dispersion (no surfactant) was subjected to constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution in the same manner as in Example 1. I made a measurement. Table 1 shows the results.
Also, a 10% by mass aqueous cellulose fiber dispersion was diluted with ion-exchanged water to obtain a 0.5% by mass cellulose fiber dispersion. The resulting aqueous dispersion was spray-dried using a spray dryer (manufactured by Fujisaki Electric Co., Ltd., device name: MDL-050B).
By spray-drying, a dried cellulose fiber from which water was removed was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Comparative Example 1]
Constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size measurement were performed in the same manner as in Example 1, except that FMa-10010 (10% by mass cellulose aqueous dispersion manufactured by Sugino Machine Co., Ltd.) was used as the raw material. Distribution measurements were taken. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Comparative Example 2]
BMa-10010 (10 mass % cellulose aqueous dispersion manufactured by Sugino Machine Co., Ltd.) was used as a raw material. Subsequent steps were the same as in Example 1, and constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution measurement were carried out. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Comparative Example 3]
A cellulose fiber aqueous dispersion was prepared using cotton derived from cotton as raw material cellulose. First, cotton was pulverized in a cutting mill (manufactured by Fritsch, device name: Pulverisette 15) to obtain cotton powder-like cellulose. A dispersion liquid was prepared with ion-exchanged water so as to have a concentration of 10% by mass of the obtained cotton powder-like cellulose without carrying out fibrillation treatment by a wet micronization device. Subsequent steps were the same as in Example 1, and constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution measurement were carried out. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Comparative Example 4]
As a raw material, a low fibrillated product of WFo-10010 (10% by mass cellulose aqueous dispersion manufactured by Sugino Machine Co., Ltd., one fibrillated product) was used. Subsequent steps were carried out in the same manner as in Example 1 to prepare a cellulose fiber aqueous dispersion. Constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution measurement were carried out in the same manner as in Example 1. Table 1 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. It was observed in the same manner as in Example 1 whether the dried cellulose fibers obtained were fibrous or not, and if fibrous, the average fiber diameter was measured. Table 1 shows the results.

[Examples 6 to 8]
The 10% by mass aqueous cellulose fiber dispersion obtained in Example 2 was used. Constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution measurement were carried out in the same manner as in Example 1. Table 2 shows the results.
In addition, the same procedure as in Example 1 was performed except that a condensed ricinoleic acid ester (product name: CRS-75, manufacturer: Sakamoto Yakuhin Kogyo Co., Ltd.) was added as a surfactant to 100 parts by mass of cellulose fibers in the amount shown in Table 2. to obtain a dried cellulose fiber. Thereafter, it was observed whether or not the dried cellulose fibers were fibrous, and if fibrous, the average fiber diameter was measured. Table 2 shows the results.

[Example 9]
10 in the same manner as in Example 2 except that oleic acid (product name: oleic acid, manufacturer name: Fuji Film Wako Pure Chemical Industries) as a surfactant was added in the amount shown in Table 2 to 100 parts by mass of cellulose fibers. A cellulose fiber aqueous dispersion of mass % was prepared. Constituent sugar analysis, molecular weight measurement, X-ray diffraction measurement, average fiber diameter measurement, and particle size distribution measurement were carried out in the same manner as in Example 1. Table 2 shows the results.
Also, in the same manner as in Example 1, a dried cellulose fiber was obtained. Thereafter, it was observed whether or not the dried cellulose fibers were fibrous, and if fibrous, the average fiber diameter was measured. Table 2 shows the results.

From Tables 1 and 2, in all the examples, it was possible to produce dried cellulose fibers in a dry state with an average fiber diameter of 0.1 μm or more and 20 μm or less.
The fiber length of the cellulose fibers in the aqueous dispersions of Examples was 10 times or more the diameter of each fiber.

Next, the resulting dried cellulose fiber and resin were combined. Examples are shown below. In addition, the following evaluation was performed about the resin after compounding.

(Confirmation of dispersibility of cellulose fibers in resin)
For evaluation of dispersibility, a resin press sheet combined with cellulose fibers was observed with a microscope (manufactured by Keyence Corporation, device name: VHX-500), and 50 points were observed within a viewing angle of 3.1 mm × 4.3 mm. Using the dispersion evaluation indices shown in Table 3, the presence or absence of aggregates and their sizes were measured, and the dispersibility of each dried product in the resin was evaluated. Agglomerates were determined based on the size of 200 μm or more in maximum diameter.

(Tensile test)
A precision universal tester (manufactured by Shimadzu Corporation, device name: Autograph AG-50KNXD) was used to perform a tensile test at 25° C. in accordance with JIS K7161 to measure tensile strength, tensile modulus and strain. A predetermined dumbbell piece (JISK7161) was obtained by injection molding with a total length of 150 mm, an edge portion width of 20 mm, a thickness of 3.25 mm, and a narrow portion width of 12.7 mm. The test conditions were set at a test speed of 10 mm/min and a distance between grips of 60 mm.

[Example 10]
(Composite with polypropylene and evaluation)
The dried cellulose fiber obtained in Example 2, maleic acid-modified polypropylene (product name: Yumex Y-1010, manufacturer name: Sanyo Kasei), and polypropylene (product name: PX600N, manufacturer name: SunAllomer) are blended as shown in Table 4. After weighing as above, they were stirred and mixed for 1 minute using a blender at 20,000 rpm. After that, melt-kneading was performed using a twin-screw kneader (manufactured by Xplore Instruments). The kneading conditions were 200° C., 120 rpm, and the kneading time was 10 minutes. After kneading, a cellulose fiber resin composite was produced as a predetermined dumbbell piece (JISK7161) by injection molding.

The obtained dumbbell piece was subjected to a tensile test with a precision universal tester (manufactured by Shimadzu Corporation, product name: Autograph AG-50KNXD) after conditioning for 7 days or longer. The test conditions were set at a test speed of 10 mm/min and a distance between grips of 60 mm. Table 4 shows the results of mechanical properties (tensile strength, tensile modulus, strain). Further, the strand obtained after kneading was cut into a length of about 3 mm to obtain a composite resin pellet. The resulting composite resin pellets were sandwiched between Teflon (registered trademark) sheets and pressed at 200° C. for 2 minutes at 12 MPa using a heat press to obtain a pressed resin sheet. The obtained resin press sheet was observed with a microscope, and the presence or absence of aggregates and their sizes were measured using the dispersion evaluation method shown in Table 3 to evaluate the dispersibility in the resin.

[Comparative Example 5]
As a comparative example of a resin body containing no cellulose fiber, a sample was prepared at the blending ratio shown in Table 4. A test piece was fabricated in the same manner as in Example 10 and evaluated.

[Example 11]
(Composite with nylon 6 and evaluation)
After weighing the dried cellulose fibers obtained in Example 2 and nylon 6 (product name: Amilan CM1007, manufacturer name: Toray) at the compounding ratio shown in Table 5, stir and mix for 1 minute at 20,000 rpm using a blender. bottom. After stirring and mixing, the mixture was dried in an oven at 80° C. for 2 days to remove moisture. After that, melt-kneading was performed using a twin-screw kneader (manufactured by Xplore Instruments). The kneading conditions were 260° C., 120 rpm, and the kneading time was 8 minutes. After kneading, a cellulose fiber resin composite was produced as a predetermined dumbbell piece (JISK7161) by injection molding.

The obtained dumbbell piece was subjected to a tensile test with a precision universal tester (manufactured by Shimadzu Corporation, product name: Autograph AG-50KNXD) after conditioning for 7 days or more. The test conditions were set at a test speed of 10 mm/min and a distance between grips of 60 mm. Table 5 shows the obtained mechanical properties (tensile strength, tensile modulus, strain). Further, the strand obtained after kneading was cut into a length of about 3 mm to obtain a composite resin pellet. The resulting composite resin pellets were sandwiched between Teflon (registered trademark) sheets and pressed at 260° C. for 2 minutes at 12 MPa using a heat press to obtain a pressed resin sheet. The obtained resin press sheet was observed with a microscope, and the presence or absence of aggregates and their sizes were measured using the dispersion evaluation method shown in Table 3 to evaluate the dispersibility in the resin.

[Comparative Example 6]
As a comparative example of a resin body containing no cellulose fiber, a sample was prepared from nylon 6 alone at the compounding ratio shown in Table 5. Also, a test piece was prepared by the same method as in Example 11 and evaluated.

Claims (7)

A cellulose fiber aqueous dispersion containing cellulose fibers,
The average fiber diameter of the cellulose fibers is 1 μm or more and 17 μm or less,
A cellulose fiber aqueous dispersion, wherein the proportion of hemicellulose in the constituent sugar components of the cellulose fibers is 50% or less, and the viscosity average molecular weight of the cellulose fibers is 100,000 or more. The cellulose fiber aqueous dispersion according to claim 1, wherein the cellulose fiber has cellulose type I crystals. 3. The aqueous cellulose fiber dispersion according to claim 1, further comprising a surfactant. 4. The aqueous cellulose fiber dispersion according to claim 3, wherein the surfactant is at least one selected from the group consisting of stearic acid, oleic acid, glycerin and polyglycerin derivatives. The cellulose fiber aqueous dispersion according to claim 3 or 4, wherein the surfactant is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the cellulose fibers. The cellulose fiber aqueous dispersion according to any one of claims 1 to 5, wherein the cellulose fiber has a viscosity average molecular weight of 200,000 or more. The cellulose fiber aqueous dispersion according to any one of claims 1 to 6, wherein the hemicellulose content is 5% or less.