JP2021155491A - Composite particles containing fine cellulose fiber, and resin composition containing composite particles - Google Patents

Abstract

To provide fine cellulose fiber-containing composite particles which can impart a resin composition having good physical properties by uniformly dispersing fine cellulose fibers even in a dry state into a resin, and a resin composition containing the composite particles.SOLUTION: Composite particles contain fine cellulose fibers and an amide compound, in which viscosity η100 at 25°C and a shear rate of 100 sec-1 of a slurry obtained by dispersing the composite particles in water with a fine cellulose fiber concentration of 0.5 mass% is 20 mPa s or more.SELECTED DRAWING: None

Description

The present invention relates to composite particles containing fine cellulose fibers and a resin composition containing the composite particles.

In recent years, in the fields of automobiles, electric appliances, etc., it has been actively made to replace parts from metal to resin in order to reduce the weight of products. In such applications, the mechanical properties and dimensional stability of the resin alone are often insufficient, and various inorganic materials such as glass fiber, carbon fiber, talc, and clay are generally added as fillers. .. However, since these fillers have a large specific gravity, there is a problem that the weight of the resin molded product becomes large.

On the other hand, cellulose is known to have a high elastic modulus comparable to that of aramid fiber and a coefficient of linear expansion lower than that of glass fiber. Also, the true density of 1.56 g / cm ^3, low, and the glass used as a general filler (density 2.4~2.6g / cm ³⁾ and talc (density 2.7 g / cm ³⁾ Comparative It is an overwhelmingly light material. It exists in large quantities on the earth as a natural resource, and is expected as an environment-friendly resin reinforcing filler from the viewpoint of carbon neutrality. Among them, in recent years, cellulose nanofibers obtained by beating and crushing cellulose fibers at a high level to make them finer (fibrillated) to a fiber diameter of 1 μm or less have been attracting attention as fillers.

In a resin composition containing a cellulose fiber and a resin, the resin forming the matrix is often hydrophobic, while the cellulose fiber is hydrophilic, so that the cellulose fiber is uniformly dispersed in the matrix resin to form the matrix resin. Various attempts have been made to improve the affinity between the resin and the cellulose fiber.

Patent Document 1 describes nanofibers of polysaccharides such as cellulose, lignocellulose, chemically modified cellulose, chemically modified lignocellulose, chitin, and chitosan, a dispersion containing a dispersion medium and a monomer, and nanofibers of the polysaccharide. A method for producing a resin composition, which comprises mixing a monomer with a mixture of and a dispersion medium and then polymerizing the monomer to form a resin, will be described.

Patent Document 2 is characterized in that when lactams are polymerized in the presence of an alkali catalyst and an initiator, a solid filler having any size of 1 μm or less is polymerized in the lactams in a dispersed manner. A method for producing a polyamide composite material is described, and carbon black, carbon nanotubes, and cellulose nanofibers are exemplified as solid fillers.

Patent Document 3 exemplifies a CNF-dried solid product obtained by drying a cellulose nanofiber (CNF) dispersion liquid with a water-soluble polymer such as carboxymethyl cellulose added in an amount of 5 to 300% by weight.

Patent Document 4 exemplifies a cellulose preparation containing cellulose particles and a surfactant that covers at least a part of the surface of the cellulose particles.

International Publication No. 2016/129963 JP-A-2018-162363 Japanese Unexamined Patent Publication No. 2017-8176 JP-A-2018-109138

The techniques described in Patent Documents 1 and 2 are to disperse the filler in the resin monomer and then polymerize the resin monomer, and the filler can be uniformly dispersed in the resin composition to some extent. Conceivable. However, in particular, fine cellulose fibers are difficult to disperse highly and uniformly in a medium once dried due to the influence of the high hydrophilicity of cellulose molecules, and even with the techniques described in Patent Documents 1 and 2. , The dispersion uniformity of the filler is not sufficient. The technique described in Patent Documents 3 and 4 is to dry a cellulose nanofiber slurry containing a water-soluble polymer or a surfactant to obtain a fine cellulose fiber dried product in which cellulose nanofibers are uniformly dispersed even in a resin composition. What you get. However, even with these techniques, the dispersion uniformity of the filler is not sufficient.

The mechanical properties and thermal dimensional stability of the resin composition in which the dispersion of the fine cellulose fibers is non-uniform is inferior to that of the resin composition in which the same amount of fine cellulose fibers are uniformly dispersed. In addition, if the fine cellulose fibers are not sufficiently dispersed in the resin composition to form agglomerates, the molded product obtained from the resin composition is likely to be broken from the agglomerates (that is, in the vicinity of the agglomerates). Is a strength defect). In a resin composition using fine cellulose fibers as a filler, further improvement in mechanical properties, thermal dimensional stability, etc. is required, and a fine cellulose fiber-containing resin composition satisfying such high required properties. Has not been provided yet.

The present invention solves the above-mentioned problems, and in one aspect, provides a resin composition having excellent mechanical properties, thermal dimensional stability, etc. by allowing fine cellulose fibers to be uniformly dispersed in the resin even from a dry state. Provided are fine cellulose fiber-containing composite particles capable of being formed, and a resin composition containing the composite particles.

The present invention includes the following aspects.
[1] Composite particles containing fine cellulose fibers and an amide compound.
A composite particle having a viscosity η ₁₀₀ of 20 mPa · s or more at ^{25 ° C. and a shear rate of 100 seconds-1} of a slurry obtained by dispersing the composite particles in water at a fine cellulose fiber concentration of 0.5% by mass.
[2] The composite particle according to the above aspect 1, wherein the liquid fraction is 30% by mass or less.
[3] of the slurry is 25 ° C. and the difference between the viscosity eta ₃₀ in viscosity eta ₁₀₀ and 25 ° C. and a shear rate of 30 sec ^-1 at a shear rate of 100 sec ^-1 is 20 mPa · s or more, the aspect 1 or 2 The composite particles described in.
[4] The composite particle according to any one of the above aspects 1 to 3, wherein the slurry exhibits viscosity hysteresis at 25 ° C. and a shear rate of 30 seconds- ^{1 or less.}
[5] The composite particle according to any one of the above aspects 1 to 4, wherein the fine cellulose fiber has a fiber diameter of 2 nm or more and less than 1000 nm.
[6] The composite particle according to any one of the above aspects 1 to 5, wherein the fine cellulose fiber is a chemically modified fine cellulose fiber.
[7] The composite particle according to the above aspect 6, wherein the chemical modification is esterification.
[8] The composite particle according to the above aspect 7, wherein the esterification is acetylation.
[9] The composite according to any one of the above aspects 1 to 8, wherein the fine cellulose fibers have a weight average molecular weight (Mw) of 100,000 or more and a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 6 or less. particle.
[10] The composite particle according to any one of the above aspects 1 to 9, wherein the average content of the acid-insoluble component of the fine cellulose fiber is 10% by mass or less.
[11] The composite particle according to any one of the above aspects 1 to 10, wherein the alkali-soluble polysaccharide content of the fine cellulose fiber is 12% by mass or less.
[12] The composite particle according to any one of the above aspects 1 to 11, wherein the amide compound has an amide bond in the molecular skeleton.
[13] The composite particle according to any one of the above aspects 1 to 12, wherein 1 g or more of the amide compound is dissolved in 100 g of water at 25 ° C.
[14] The composite particle according to any one of the above aspects 1 to 13, wherein the amide compound has a moisture absorption rate of 10% or more at 23 ° C. and 60% RH.
[15] Any of the above embodiments 1 to 14, wherein the difference ΔYI between the yellowness of the amide compound and the yellowness after heating the amide compound at 190 ° C. in a nitrogen atmosphere for 4 hours is 30 or less. The composite particles described in.
[16] The composite particle according to any one of the above aspects 1 to 15, wherein the amide compound has a melting point of 300 ° C. or lower.
[17] The composite particle according to any one of the above aspects 1 to 16, wherein the amide compound is a cyclic amide.
[18] The composite particle according to any one of the above aspects 1 to 17, wherein the amide compound is caprolactam.
[19] The composite particle according to any one of the above aspects 1 to 18, wherein the median particle size of the composite particle is 1 μm to 5000 μm.
[20] The method for producing composite particles according to any one of the above aspects 1 to 19.
Preparing a slurry of fine cellulose fibers and
The slurry and the amide compound are mixed and then dried.
Including methods.
[21] A resin composition containing the composite particles according to any one of the above aspects 1 to 19 and a resin.
[22] A method for producing a resin composition containing fine cellulose fibers, an amide compound, and a resin.
A method comprising mixing the composite particles according to any one of the above aspects 1 to 19 with a resin.
[23] A resin pellet formed from the resin composition according to the above aspect 21.
[24] A resin molded product formed from the resin composition according to the above aspect 21.

According to one aspect of the present invention, the fine cellulose fibers can be uniformly dispersed in the resin even from a dry state, so that a resin composition having excellent mechanical properties and thermal dimensional stability can be provided. A fiber-containing composite particle and a resin composition containing the composite particle can be provided.

It is explanatory drawing of the measurement method of viscosity hysteresis and the maximum viscosity difference (Δη _max). It is explanatory drawing of the calculation method of IR index 1730 and IR index 1030. It is an explanatory view of a method of measuring the thermal decomposition temperature (T _D) and 1% weight loss temperature (T _1%).

Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to these aspects.

≪Composite particles≫
One aspect of the present invention provides composite particles containing fine cellulose fibers and a compound having an amide bond (also referred to as an amide compound). The amide compound can function as a dispersant for the fine cellulose fibers. The present inventors have found that the amide compound can significantly improve the dispersibility of the fine cellulose fibers when the fine cellulose fibers are dispersed in the resin. Once the fine cellulose fibers are dried, the cellulose molecules interact with each other extremely strongly due to hydrogen bonds, and even if they try to disperse again in a fluid, uniform dispersion is difficult. When the fluid is a hydrophobic fluid such as a resin monomer or a molten resin, it is particularly difficult to disperse the fine cellulose fibers. However, according to the composite particles of the present disclosure containing the fine cellulose fibers and the amide compound, even when the fine cellulose fibers once dried are dispersed in the fluid, the fine cellulose fibers can be dispersed very well. It will be possible. Although the reason is not clear, the amide compound is a fine cellulose fiber because the interaction with the fine cellulose fiber of the amide bond (for example, the hydrogen bond between the amide bond and the hydrogen bond in the cellulose molecule) is appropriate. It is presumed that the agglomeration of the fine cellulose fibers is prevented extremely well and the dispersibility of the fine cellulose fibers is improved.

In one preferred embodiment, the liquid fraction of the composite particle is 30% by mass or less, or 20% by mass or less, or 10% by mass or less, or 8% by mass or less, or 5% by mass or less, or 3% by mass or less, or 1. It is mass% or less. The lower the liquid fraction is, the more desirable it is, but from the viewpoint of ease of producing composite particles, for example, it may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more. The liquid fraction is a value measured when the sample is heated at 150 ° C. using a heat-drying moisture meter (A & D Co., Ltd., MX-50).

The liquid contained in the composite particles is not particularly limited, and examples thereof include water and an organic solvent. As the organic solvent, a water-soluble organic solvent capable of dissolving 1 g / L or more in water is preferable. Specifically, for example, alcohols having 1 to 6 carbon atoms such as methanol, ethanol and propanol, preferably 1 to 4 carbon atoms; ketones having 3 to 6 carbon atoms such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethylene glycols. , Alkylene glycol having 2 to 6 carbon atoms such as propylene glycol; linear or branched saturated or unsaturated hydrocarbon having 1 to 6 carbon atoms; aromatic hydrocarbons such as benzene and toluene; methylene chloride, chloroform and the like Examples thereof include halogenated hydrocarbons; lower alkyl ethers having 2 to 5 carbon atoms; polar solvents such as DMSO, DMF, DMAc, and NMP. These can be used alone or in combination of two or more, but from the viewpoint of operability in the production of composite particles, water, alcohol having 1 to 6 carbon atoms, ketone having 3 to 6 carbon atoms, and 2 carbon atoms. Alkylene glycol of ~ 6, DMSO, DMF, DMAc, NMP and the like are preferable.

In one embodiment, a slurry of composite particles dispersed in water at a fine cellulose fiber concentration of 0.5% by mass has a viscosity η _{100 at} ^{25 ° C. and a shear rate of 100 seconds-1} (in the present disclosure, simply "viscosity η _100". ”) Is 20 mPa · s or more, preferably 25 mPa · s or more, more preferably 30 mPa · s or more, and further preferably 40 mPa · s or more. When a resin composition is prepared using composite particles having a viscosity η ₁₀₀ of 20 mPa · s or more, the dispersibility of the fine cellulose fibers in the resin composition is good, and the mechanical strength and dimensional stability can be improved. It is advantageous. On the other hand, the viscosity eta ₁₀₀ more excellent dispersibility in water is no particular upper limit of the viscosity eta ₁₀₀ is to rise. The higher the viscosity η ₁₀₀ , the better the dispersibility of the fine cellulose fibers in the resin composition, and it is possible to achieve good mechanical strength improvement and dimensional stability improvement. In one embodiment, from the viewpoint of ease of producing composite particles, _{the upper limit of the viscosity η 100} is 1000 mPa · s or less, or 500 mPa · s or less, or 200 mPa · s or less, or 150 mPa · s or less, or 100 mPa · s or less. It may be there.

In one embodiment, a slurry obtained by dispersing composite particles in water at a fine cellulose fiber concentration of 0.5% by mass at a shear rate of 30 seconds- ¹ with respect to a viscosity η ₁₀₀ ^{at a shear rate of 100 seconds-1 at 25 ° C.} The ratio of viscosity η ₃₀ to η ₃₀ / η ₁₀₀ (also referred to as thixotropy index (TI) in the present disclosure) is more than 1. The TI is preferably 2 or more, 3 or more, or 5 or more, or 7 or more. Originally, the dispersion liquid in which the fine cellulose fibers are sufficiently dispersed has a structural viscosity that decreases as the shear rate increases. The fact that the TI is in the above range indicates that the dispersibility of the fine cellulose fibers in the dispersion is good, and when a resin composition is prepared using such composite particles, the fine cellulose fibers in the resin composition are produced. The dispersibility of the resin is also good, which is advantageous in improving the mechanical strength and the dimensional stability. The TI is preferably large from the viewpoint of dispersibility of the fine cellulose fibers, but may be, for example, 50 or less, 40 or less, or 30 or less from the viewpoint of ease of producing composite particles.

In one embodiment, the slurry in which the composite particles are dispersed in water at a fine cellulose fiber concentration of 0.5% by mass exhibits viscosity hysteresis at ^{25 ° C. and a shear rate of 30 seconds-1 or less.} Here, to show viscosity hysteresis at 25 ° C. and a shear rate of 30 seconds- ¹ or less, the shear rate is increased ^{from 1 second-1} to 100 seconds- ¹ over 100 seconds with a double-cylindrical geometry using a leometer. After that, in the third cycle when the cycle of lowering to ^{1 second-1} over 100 seconds was performed three times, there was a viscosity difference between the time when the shear rate increased and the time when the shear rate decreased in the region where the shear rate was ^{30 seconds-1 or less.} However, it means that the maximum viscosity difference (Δη _max ) is 5 mPa · s or more (see FIG. 1). The viscosity hysteresis correlates with the degree of fibril development of the fine cellulose fibers, and the larger the hysteresis, the better the development of fibrils, and the more excellent the degree of network formation by the fine cellulose fibers in the resin composition. As a result, the mechanical strength and dimensional stability of the resin composition are improved. The maximum viscosity difference Δη _max is preferably 10 mPa · s or more, 15 mPa · s or more, 20 mPa · s or more, or 30 mPa · s or more. The maximum viscosity difference Δη _max is preferably large from the viewpoint of the physical properties of the resin composition, but from the viewpoint of ease of producing composite particles, for example, at 200 mPa · s or less, 150 mPa · s or less, or 100 mPa · s or less. It may be there.

Slurry, the difference between the viscosity eta ₃₀ in viscosity eta ₁₀₀ and 25 ° C. and a shear rate of 30 sec ^-1 at 25 ° C. and a shear rate of 100 sec ^-1 (.DELTA..eta _30-100), from the viewpoint of obtaining good viscosity hysteresis, Preferably, it is 20 mPa · s or more, 25 mPa · s or more, or 30 mPa · s or more, and from the viewpoint of ease of producing composite particles, for example, 100 mPa · s or less, 80 mPa · s or less, or 50 mPa · s or less. May be.

To measure the viscosities (η ₃₀ and η ₁₀₀ ) of the present disclosure, first, a predetermined amount of composite particles are added to water so that the fine cellulose fibers are 0.5% by mass, and 20 ml of an aqueous slurry containing the composite particles is prepared. .. The dispersion conditions are as follows. That is, the composite particles are lightly loosened in a mortar while adding distilled water to the composite particles little by little. Finally, distilled water is added to the composite particles so that 20 g of fine cellulose fibers is 0.5% by mass in a glass vial having a capacity of 30 ml to prepare 20 g of the test dispersion. The obtained test dispersion liquid (20 g) is dispersed with a homogenizer (manufactured by IKA, trade name "Ultratalax T18", rotation speed 10000 rpm, 5 minutes). After confirming that the liquid temperature is 25 ° C., a part of the slurry being stirred is taken and the viscosity is immediately measured with a rheometer using a double-cylindrical geometry. The temperature of the device is adjusted to 25 ° C. in advance. As a measurement condition, the shear rate is ^{increased from 1 second-1} to 100 seconds- ¹ over 100 seconds, and ^{then decreased from 1 second-1} over 100 seconds three times, and the viscosity is increased every second. Get the data. Then, the viscosity when the shear rate R seconds ^{-1 at} the time of the _{third rise is η R} (for example, when it is ^{10 seconds -1} , it is expressed as _{η 10).}

In the present disclosure, the median particle size of the composite particle is a value measured by a laser diffraction type particle size distribution measuring device or an image analysis type particle size distribution measuring device. The numerical values of the median particle diameter of the present disclosure are intended to be the numerical values obtained by at least one of these devices. The lower limit of the median particle size is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, and particularly preferably 10 μm or more. The upper limit is preferably 5000 μm or less, more preferably 3000 μm or less, still more preferably 1000 μm or less, and particularly preferably 500 μm or less. When the median particle size is 1 μm or more, it is not necessary to use a special method in the production in order to prevent the secondary agglutination of the primary particles, which is preferable from the viewpoint of the production process and cost. On the other hand, when the median particle size is 5000 μm or less, the kneading of the composite particles and the resin (that is, the base resin) in the resin composition is stable in the production of the resin composition using an extruder or the like, and as a result, the fine cellulose fibers are produced. It is preferable because the dispersibility in the resin composition is good.

Hereinafter, an exemplary embodiment of each component of the composite particle will be described.

<Fine cellulose fiber>
The fine cellulose fibers may be obtained from various cellulose fiber raw materials selected from natural cellulose and regenerated cellulose. Natural cellulose includes wood pulp obtained from wood species (hardwood or coniferous tree), non-wood pulp obtained from non-wood species (cotton, bamboo, hemp, bagasse, kenaf, cotton linter, sisal, walla, etc.), and animals (for example, straw). Cellulose fiber aggregates produced by kenaf), algae, and microorganisms (eg, acetic acid) can be used. As the regenerated cellulose, regenerated cellulose fibers (viscose, cupra, tencel, etc.), cellulose derivative fibers, regenerated cellulose obtained by an electrospinning method, or ultrafine threads of a cellulose derivative can be used. These raw materials are adjusted in fiber diameter, fiber length, degree of fibrillation, etc. by beating, fibrillation, miniaturization, etc. by mechanical force such as grinder, refiner, etc., and bleached and purified using chemicals, if necessary. However, the content of components other than cellulose (acid-insoluble components such as lignin, alkali-soluble polysaccharides such as hemicellulose, etc.) can be adjusted.

In one embodiment, the cellulose fiber raw material may be chemically modified and is an inorganic esterified product such as nitrate ester, sulfuric acid ester, phosphoric acid ester, silicic acid ester, methyl ether, hydroxyethyl ether, hydroxypropyl ether, hydroxybutyl ether, carboxymethyl ether. , Esterized products such as cyanoethyl ether, TEMPO oxidation-treated pulp obtained by oxidizing the primary hydroxyl group of cellulose, and the like can be used as a raw material for cellulose fibers.

In one embodiment, the number average fiber diameter of the fine cellulose fibers is 2 nm or more, preferably 4 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, and particularly preferably 30 nm or more. On the other hand, the upper limit is less than 1000 nm in one embodiment, preferably 800 nm or less, more preferably 500 nm or less, still more preferably 300 nm or less. When the number average fiber diameter is 2 nm or more, the crystallinity of cellulose is well maintained, which is preferable. When the number average fiber diameter is less than 1000 nm, the performance improving effect when used as a filler of the resin composition is good.

The number average fiber length / number average fiber diameter (L / D) of the fine cellulose fibers is preferably 50 from the viewpoint of satisfactorily improving the mechanical properties of the resin composition containing the fine cellulose fibers with a small amount of fine cellulose fibers. More than or equal to, or more than 80, or more than 100, or more than 120, or more than 150. The upper limit is not particularly limited, but is preferably 5000 or less from the viewpoint of handleability.

In one embodiment, the fine cellulose fibers are beaten and fibrillated by mechanical force such as a beater or refiner, and then crushed by a high-pressure homogenizer, a microfluidizer, a ball mill, a disc mill, a mixer (for example, a homomixer) or the like. It is a fine cellulose defibrated by.

In one aspect, as a method for obtaining fine cellulose fibers, a method for refining the cellulose fiber raw material can be exemplified. The miniaturization treatment can be carried out by a known miniaturization treatment method. For example, in the case of obtaining fine cellulose fibers having a number average fiber diameter of less than 1000 nm (for example, 2 nm or more and less than 1000 nm) from fibers having a number average fiber diameter of 1 μm or more, in water or an organic solvent, for example, a grinder such as a mass colloider, etc. Alternatively, miniaturization can be performed by performing a treatment using a high-pressure homogenizer.

The organic solvent used for the micronization treatment is not particularly limited, but is, for example, an alcohol having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms such as methanol, ethanol and propanol; carbons such as acetone, methyl ethyl ketone and methyl isobutyl ketone. Ketones of number 3 to 6; linear or branched saturated or unsaturated hydrocarbons with 1 to 6 carbon atoms; aromatic hydrocarbons such as benzene and toluene; halogenated hydrocarbons such as methylene chloride and chloroform; carbon Lower alkyl ethers of number 2-5; polar solvents such as DMSO, DMF, DMAc, NMP, diesters of succinic acid and triethylene glycol monomethyl ether and the like are exemplified. These can be used alone or in combination of two or more, but from the viewpoint of operability of the micronization treatment, an alcohol having 1 to 6 carbon atoms, a ketone having 3 to 6 carbon atoms, and 2 to 5 carbon atoms can be used. Lower alkyl ethers, DMSO, DMF, DMAc, NMP, methyl succinate triglycol diester, toluene and the like are preferred.
The amount of water or an organic solvent used in the micronization treatment may be an effective amount capable of dispersing the fibers before the micronization, and is not particularly limited, but is preferably 1% by mass or more with respect to the fibers before the micronization. It is more preferably 10 mass times or more, further preferably 50 mass times or more, preferably 2000 mass times or less, and more preferably 1000 mass times or less.

Further, as an apparatus used in the miniaturization process, a known disperser is preferably used. For example, a breaker, a beater, a refiner, a low pressure homogenizer, a high pressure homogenizer, an ultrahigh pressure homogenizer, a homomixer, a grinder, a mass colloider, a cutter mill, a ball mill, a jet mill, a single shaft extruder, a twin shaft extruder, an ultrasonic stirrer, A household juicer mixer or the like can be used. The fine cellulose fibers can be recovered in the form of a dispersion or a dried product in a liquid medium. The liquid medium in the dispersion may further contain, in addition to water, any other liquid medium (eg, one or more of the organic solvents exemplified above), either alone or in combination of two or more.

In the present disclosure, the number average fiber diameter, the number average fiber length, and the L / D ratio of the fine cellulose fibers are set to 0. Dilute to 001 to 0.1% by mass, use a high shear homogenizer (for example, manufactured by IKA, trade name "Ultratalax T18"), and disperse under the treatment conditions: rotation speed 25,000 rpm x 5 minutes, and perform a hydrophilic substrate (for example, manufactured by IKA, trade name "Ultratalax T18"). For example, it is cast on mica) and air-dried as a measurement sample, and measured with a high-resolution scanning electron microscope (SEM) or an interatomic force microscope (AFM). Specifically, the length (L) and diameter (D) of 100 fibrous substances randomly selected in the observation field of view adjusted so that at least 100 fibrous substances are observed. Is measured and the ratio (L / D) is calculated. For the fine cellulose fibers, the number average value of the length (L), the number average value of the diameter (D), and the number average value of the ratio (L / D) are calculated.

In a typical embodiment, the crystal structure of the fine cellulose fibers has cellulose type I and / or type II. As the crystal form of cellulose, type I, type II, type III, type IV and the like are known. Type I and type II celluloses are widely used, while type III and type IV celluloses are available on the laboratory scale but not on the industrial scale.

The crystal structure can be identified from the diffraction profile obtained by wide-angle X-ray diffraction using CuKα (λ = 0.15418 nm) monochromatic with graphite. Cellulose type I has peaks at two positions, around 2θ = 14 to 17 ° and around 2θ = 22 to 23 °. Cellulose type II has one peak at 2θ = 10 ° to 19 ° and two peaks at 2θ = 19 ° to 25 °. When cellulose type I and cellulose type II are mixed, a maximum of 6 peaks are observed in the range of 2θ = 10 ° to 25 °.

The crystallinity of the fine cellulose fibers of the present embodiment is preferably 50% or more. When the crystallinity is in this range, the mechanical properties (particularly strength and dimensional stability) of the fine cellulose fibers are enhanced, so that the strength and dimensional stability of the resin composition obtained by dispersing the fine cellulose fibers in the resin is enhanced. There is a tendency. The crystallinity of the fine cellulose fibers of the present embodiment is more preferably 60% or more, further preferably 65%, and most preferably 70%. The higher the crystallinity of the fine cellulose fibers, the more preferable it is. Therefore, the upper limit is not particularly limited, but 99% is the preferable upper limit from the viewpoint of production.

When the fine cellulose fiber is a cellulose type I crystal (derived from natural cellulose), the crystallinity is determined by the Segal method from the diffraction pattern (2θ / deg. Is 10 to 30) when the sample is measured by wide-angle X-ray diffraction. Therefore, it is calculated by the following formula.

Crystallinity (%) = [I ₍₂₀₀₎ −I _(amorphous) ] / I ₍₂₀₀₎ × 100
I _{(200) : Diffraction peak intensity due to amorphous in the} cellulose type I crystal by 200 planes (2θ = 22.5 °) I (amorphous): Hello peak intensity due to amorphous in the cellulose type I crystal, 4 from the diffraction angle of 200 planes Peak intensity on the low angle side (2θ = 18.0 °) of .5 °

The degree of crystallinity is 2θ = 12.6, which is assigned to the (110) plane peak of the cellulose type II crystal in wide-angle X-ray diffraction when the fine cellulose fiber is a cellulose type II crystal (derived from regenerated cellulose). From the absolute peak intensity h0 at ° and the peak intensity h1 from the baseline at this surface spacing, it is calculated by the following formula.
Crystallinity (%) = h1 / h0 × 100

The degree of polymerization (DP) of the fine cellulose fibers is preferably 100 or more and 12000 or less. The degree of polymerization is the number of repetitions of anhydrous glucose units that form a cellulose molecular chain. When the degree of polymerization of the cellulose fiber is 100 or more, the tensile breaking strength and elastic modulus of the fiber itself are improved, and the high tensile breaking strength and thermal stability of the resin composition containing the fine cellulose fiber are exhibited, which is preferable. There is no particular upper limit to the degree of polymerization of the cellulose fiber, but cellulose having a degree of polymerization exceeding 12000 is practically difficult to obtain and tends to be difficult to be used industrially. From the viewpoint of handleability and industrial implementation, the degree of polymerization of the fine cellulose fibers is preferably 150 to 8000. The degree of polymerization was determined by first determining the ultimate viscosity of a diluted cellulose solution using a copper ethylenediamine solution (JIS P 8215: 1998), and then utilizing the relationship between the ultimate viscosity of cellulose and the degree of polymerization DP by the following formula. Therefore, it is obtained as the degree of polymerization DP.
Extreme viscosity [η] = K × DPa
Here, K and a are constants determined by the type of polymer, and in the case of cellulose, K is 5.7 × 10 ^-3 and a is 1.

The weight average molecular weight (Mw) of the fine cellulose fibers is preferably 100,000 or more, more preferably 200,000 or more. The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight (Mn) of the fine cellulose fibers is preferably 6 or less, preferably 5.4 or less. The larger the weight average molecular weight, the smaller the number of terminal groups of the cellulose molecule. Further, since the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight represents the width of the molecular weight distribution, it means that the smaller the Mw / Mn, the smaller the number of terminals of the cellulose molecule. Since the end of the cellulose molecule is the starting point of thermal decomposition, not only the weight average molecular weight of the cellulose molecule of the fine cellulose fiber is large, but also when the weight average molecular weight is large and the width of the molecular weight distribution is narrow, the fine cellulose having high heat resistance is particularly high. A resin composition containing fibers and fine cellulose fibers and a resin can be obtained. The weight average molecular weight (Mw) of the cellulose fibers may be, for example, 600,000 or less, or 500,000 or less, from the viewpoint of availability of the cellulose raw material. The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight (Mn) may be, for example, 1.5 or more, or 2 or more, from the viewpoint of ease of producing cellulose fibers. The Mw can be controlled within the above range by selecting a cellulose raw material having Mw according to the purpose, appropriately performing physical treatment and / or chemical treatment on the cellulose raw material within an appropriate range, and the like. Mw / Mn also has the above range by selecting a cellulose raw material having Mw / Mn according to the purpose, appropriately performing physical treatment and / or chemical treatment on the cellulose raw material within an appropriate range, and the like. Can be controlled. In both Mw control and Mw / Mn control, the physical treatment includes dry or wet pulverization of a microfluidizer, ball mill, disc mill, etc., a crusher, a homomixer, a high-pressure homogenizer, and an ultrasonic device. Physical treatments that apply mechanical forces such as impact, shearing, shearing, and friction due to such factors can be exemplified, and examples of the chemical treatments include cooking, bleaching, acid treatment, and regenerated cellulose formation.

Here, the weight average molecular weight and the number average molecular weight of the fine cellulose fibers are defined by dissolving the fine cellulose fibers in N, N-dimethylacetamide to which lithium chloride is added, and then gelling with N, N-dimethylacetamide as a solvent. It is a value obtained by permeation chromatography.

The fine cellulose fiber of the present embodiment may contain an acid-insoluble component containing lignin and / or an alkali-soluble polysaccharide containing hemicellulose and the like. Since the contents of the acid-insoluble component and the alkali-soluble polysaccharide affect the heat resistance of the fine cellulose fibers and the dispersibility in the resin composition, they may be adjusted according to the purpose. Generally, when the content of the acid-insoluble component and the alkali-soluble polysaccharide is large, the heat resistance of the fine cellulose fiber is lowered and the discoloration is accompanied by the content, and the mechanical property of the cellulose fiber is lowered. Therefore, for example, when a resin composition is produced using a resin that is melt-kneaded at a high temperature such as a polyamide resin, it is preferable that the average content of acid-insoluble components and alkali-soluble polysaccharides in the fine cellulose fibers is small. There is.

The average content of the acid-insoluble component of the fine cellulose fiber is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 7% by mass or less, still more preferably 6% by mass or less, and most preferably 5% by mass. It is as follows. The average content of the acid-insoluble component may be 0% by mass, but from the viewpoint of ease of producing fine cellulose fibers, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more. Alternatively, it may be 2% by mass or more, or 3% by mass or more.

The average content of acid-insoluble components is determined as a quantification of acid-insoluble components using the Clarson method described in a non-patent document (Wood Science Experiment Manual, edited by Japan Wood Society, pp. 92-97, 2000). This method is understood in the art as a method for measuring the amount of lignin. The sample is stirred in a sulfuric acid solution to dissolve cellulose, hemicellulose, etc., and then filtered through a glass fiber filter paper, and the obtained residue corresponds to an acid-insoluble component. The acid-insoluble component content is calculated from the weight of the acid-insoluble component, and the number average of the acid-insoluble component contents calculated for the three samples is defined as the acid-insoluble component average content.

The average content of alkali-soluble polysaccharides in the fine cellulose fibers is preferably 25% by mass or less, more preferably 13% by mass or less, further preferably 12% by mass or less, particularly preferably 8% by mass or less, and most preferably 5. It is less than mass%. The average content of the alkali-soluble polysaccharide may be 0% by mass, but from the viewpoint of ease of producing fine cellulose fibers, for example, it may be 1% by mass or more, 3% by mass or more, or 6% by mass or more. May be good.

The alkali-soluble polysaccharides in the present disclosure include β-cellulose and γ-cellulose as well as hemicellulose. The alkali-soluble polysaccharide is a component (that is, a component obtained by removing α-cellulose from holocellulose) obtained as an alkali-soluble portion of holocellulose obtained by solvent extraction and chlorine treatment of a plant (for example, wood). Understood by those skilled in the art. Alkaline-soluble polysaccharides are polysaccharides containing hydroxyl groups and have poor heat resistance, which causes inconveniences such as decomposition when heat is applied, yellowing during heat aging, and a decrease in the strength of cellulose fibers. Therefore, it is preferable that the content of the alkali-soluble polysaccharide in the cellulose fiber is small.

The alkali-soluble polysaccharide content can be obtained from the method described in non-patent documents (Wood Science Experiment Manual, edited by Japan Wood Society, pp. 92-97, 2000), and can be obtained from the holocellulose content (Wise method). It is obtained by subtracting the α-cellulose content. This method is understood in the art as a method for measuring the amount of hemicellulose. The alkali-soluble polysaccharide content is calculated three times for one sample, and the number average of the calculated alkali-soluble polysaccharide content is defined as the alkali-soluble polysaccharide average content.

The fine cellulose fiber may be a chemically modified fine cellulose fiber chemically modified by a modifying agent. In the chemically modified fine cellulose fibers in the composite particles, aggregation due to hydrogen bonds is suppressed as compared with the unmodified fine cellulose fibers. Therefore, when the composite particles are mixed in the resin composition, the chemically modified fine cellulose fibers are uniformly dispersed in the resin, and the chemically modified fine fibers having excellent mechanical properties, heat resistance, surface smoothness and appearance are obtained. A fiber-reinforced resin composition containing the same can be obtained.
As the modifying agent for the fine cellulose fiber, a compound that reacts with the hydroxyl group of cellulose can be used, and examples thereof include an esterifying agent, an etherizing agent, a silylating agent, and an isocyanate. In a preferred embodiment, the chemical modification is acylation with an esterifying agent. As the esterifying agent, a compound selected from a compound that reacts with a hydroxyl group of cellulose to generate an acyl group, for example, a carboxylic acid halide, an acid anhydride (that is, a carboxylic acid anhydride), a carboxylic acid vinyl ester, or a carboxylic acid. Can be used. In a preferred embodiment, the esterification is acetylation. The carboxylic acids constituting each of the above-mentioned carboxylic acid halide, acid anhydride, and carboxylic acid vinyl ester include saturated fatty acids and unsaturated (mono-unsaturated, di-unsaturated, tri-unsaturated, tetra-unsaturated, and penta-unsaturated. Saturated, hexaunsaturated, etc.) Fatty acids, aromatic carboxylic acids, amino acids, imide compounds and the like can be exemplified. The carboxylic acid may be a monobasic acid or a polybasic acid. It is preferable that the carboxylic acid has a lower alkanoyloxy group (for example, 1 to 24 carbon atoms) in terms of ease of production of the esterified fine cellulose fiber.

Saturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, pivalic acid, caproic acid, enanthic acid, capric acid, pelargonic acid, capric acid, undesic acid, lauric acid, tridecic acid, myristic acid, pentadecic acid, Palmitic acid, margaric acid, stearic acid, nonadecil acid, arachidic acid and the like are preferable. Saturated fatty acids include branched chain alkylcarboxylic acids (eg, 3,5,5-trimethylhexanoic acid, etc.), cyclic alkanecarboxylic acids (cyclohexanecarboxylic acid, t-butylcyclohexanecarboxylic acid, etc.), and substituted or unsubstituted phenoxys. Alkylcarboxylic acids (phenoxyacetic acid, 1,1,3,3-tetramethylbutylphenoxyacetic acid, bornanphenoxyacetic acid, bornanphenoxyhexanoic acid, etc.) can also be mentioned.

Examples of monounsaturated fatty acids include acrylic acid, methacrylic acid, crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, ricinoleic acid and the like.
Examples of diunsaturated fatty acids include sorbic acid, linoleic acid, and eikosazienoic acid.
Examples of triunsaturated fatty acids include linolenic acid, pinolenic acid, and eleostearic acid.
Examples of tetra-unsaturated fatty acids include stearidonic acid and arachidonic acid.
Examples of the pentaunsaturated fatty acid include bosseopentaenoic acid and eicosapentaenoic acid.
Examples of hexaunsaturated fatty acids include docosahexaenoic acid and herring acid.

Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid (3,4,5-trihydroxybenzenecarboxylic acid), and silicic acid (3-phenylpropa-2-enoic acid). ) Etc. can be mentioned.
Examples of the multibasic carboxylic acid include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid.

Examples of amino acids include glycine, β-alanine, ε-aminocaproic acid (6-aminocaproic acid) and the like.

As an imide compound,
Maleimide compound:

Phthalimide compound:

At least one compound selected from the group consisting of can be exemplified.

A preferable example of the carboxylic acid halide is the following formula:
R ^1- C (= O) -X
(In the formula, R ¹ represents an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, a cycloalkyl group having 3 to 24 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and X represents an aryl group having 6 to 24 carbon atoms. , Cl, Br or I.)
At least one selected from the group consisting of the compounds represented by.

Preferable examples of carboxylic acid halides include acetyl chloride, acetyl bromide, acetyl iodide, propionyl chloride, propionyl bromide, propionyl iodide, butyryl chloride, butyryl bromide, butyryl iodide, benzoyl chloride, benzoyl bromide, Examples include, but are not limited to, benzoyl iodide. Among them, carboxylic acid chloride can be preferably adopted from the viewpoint of reactivity and handleability.

Preferable examples of acid anhydrides are saturated aliphatic monocarboxylic acid anhydrides such as acetic acid, propionic acid, (iso) butyric acid and valeric acid; and unsaturated aliphatic monocarboxylic acids such as (meth) acrylic acid and oleic acid. Anhydride; Anhydrous of alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid and tetrahydrobenzoic acid; Anhydrides of aromatic monocarboxylic acids such as benzoic acid and 4-methylbenzoic acid; As dibasic carboxylic acid anhydrides, for example. Anhydrous saturated aliphatic dicarboxylic acid such as succinic anhydride and adipic acid; anhydrous unsaturated aliphatic dicarboxylic acid anhydride such as maleic anhydride and itaconic anhydride; Alicyclic dicarboxylic acids such as phthalic acid and methyltetrahydrophthalic anhydride; as polybasic carboxylic acid anhydrides such as anhydrous aromatic dicarboxylic acid anhydrides such as phthalic anhydride and naphthalic anhydride, for example, trimellitic anhydride. , (Anhydrous) polycarboxylic acid such as pyromellitic anhydride. From the viewpoint of reaction efficiency, acetic anhydride, propionic anhydride, and butyric anhydride are preferable, and acetic anhydride is particularly preferable.

The carboxylic acid vinyl ester has the following formula:
R-COO-CH = CH ₂
(In the formula, R represents an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, or an aryl group having 6 to 16 carbon atoms.)
At least one selected from the group consisting of the compounds represented by.

Specific examples of the carboxylic acid vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylic acid, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, and stearer. At least one selected from the group consisting of vinyl acid acid, vinyl pivalate, vinyl divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl octylate, vinyl benzoate, and vinyl cinnate. Be done.

Among these carboxylic acid vinyl esters, at least one selected from the group consisting of vinyl acetate, vinyl propionate, and vinyl butyrate, particularly vinyl acetate, is preferable from the viewpoint of reaction efficiency.

The carboxylic acid has the following formula:
R-COOH ... (1)
(In the formula, R represents an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, or an aryl group having 6 to 16 carbon atoms.)
At least one selected from the group consisting of the compounds represented by.

Specific examples of carboxylic acids include acetic acid, propionic acid, butyric acid, caproic acid, cyclohexanecarboxylic acid, capric acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, pivalic acid, methacrylic acid, crotonic acid and pivalin. Included is at least one selected from the group consisting of acids, octyl acids, benzoic acids, and cinnamic acid.

Among these carboxylic acids, at least one selected from the group consisting of acetic acid, propionic acid, and butyric acid, particularly acetic acid, is preferable from the viewpoint of reaction efficiency.

The lower limit of the mass ratio of the esterifying agent to the entire reaction system is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 5% by mass or more, and particularly preferably 10% by mass or more. When it is 0.1% by mass or more, the amount of the esterifying agent is not too small, and the reactivity is good, which is preferable. On the other hand, the upper limit of the mass ratio is preferably less than 80% by mass, more preferably less than 50% by mass, and further preferably less than 30% by mass. If it is less than 80% by mass, elution of high DS cellulose is suppressed, which is preferable.

In one aspect, the reaction medium may further comprise a catalyst from the viewpoint of promoting the reaction. For example, in the reaction of a carboxylic acid halide, one or more alkaline compounds may be added for the purpose of acting as a catalyst and at the same time neutralizing an acidic substance which is a by-product. Specific examples of the alkaline compound include, but are not limited to, tertiary amine compounds such as triethylamine and trimethylamine; and nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine.

In the reaction of acid anhydride, as a catalyst, an acidic compound such as sulfuric acid, hydrochloric acid, or phosphoric acid, or a Lewis acid (for example, a Lewis acid compound represented by MYn, in which M is B, As, Ge, etc. It represents a semi-metal element, a base metal element such as Al, Bi, In, or a transition metal element such as Ti, Zn, Cu, or a lanthanoid element, and n is an integer corresponding to the atomic value of M, and 2 or 3 is used. Representing, Y represents a halogen atom, OAc, OCOCF ₃ , ClO ₄ , SbF ₆ , PF ₆ or OSO ₂ CF ₃ (OTf)), or one or more alkaline compounds such as triethylamine and pyridine are added. You may.

In the reaction of carboxylic acid vinyl ester, as a catalyst, alkali metal hydroxide, alkaline earth metal hydroxide, alkali metal carbonate, alkaline earth metal carbonate, alkali metal hydrogen carbonate, 1st to 3rd grade amines, One or more selected from the group consisting of quaternary ammonium salts, imidazoles and derivatives thereof, pyridines and derivatives thereof, and alkoxides are preferable.

Examples of the alkali metal hydroxide and alkaline earth metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide and the like. Alkali metal carbonate, alkaline earth metal carbonate, alkali metal hydrogen carbonate include lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, carbonic acid. Examples include potassium hydrogen hydrogen and cesium hydrogen carbonate.

Examples of the 1st to 3rd amines (that is, primary amines, secondary amines, and tertiary amines) include ethylenediamine, diethylamine, proline, N, N, N', N'-tetramethylethylenediamine, N, N, N'. , N'-tetramethyl-1,3-propanediamine, N, N, N', N'-tetramethyl-1,6-hexanediamine, tris (3-dimethylaminopropyl) amine, N, N-dimethylcyclohexyl Examples include amines and triethylamines.

Examples of imidazole and its derivatives include 1-methylimidazole, 3-aminopropylimidazole, carbonyldiimidazole and the like.

Examples of pyridine and its derivatives include N, N-dimethyl-4-aminopyridine, picoline and the like.

Examples of the alkoxide include sodium methoxide, sodium ethoxide, potassium-t-butoxide and the like.

In the reaction of a carboxylic acid, as a catalyst, an acidic compound such as sulfuric acid, hydrochloric acid, or phosphoric acid, or a Lewis acid (for example, a Lewis acid compound represented by MYn, where M is a half of B, As, Ge, etc.) It represents a metal element, a base metal element such as Al, Bi, In, or a transition metal element such as Ti, Zn, Cu, or a lanthanoid element, and n is an integer corresponding to the valence of M and represents 2 or 3. , Y represents halogen atom, OAc, OCOCF ₃ , ClO ₄ , SbF ₆ , PF ₆ or OSO ₂ CF ₃ (OTf)) may be added in one or more.

Esterification is preferably carried out under stirring. The stirring method is not particularly limited, but it is carried out using various stirrers (shear type, friction type, high pressure jet type, ultrasonic type, etc.), melters, emulsifiers, dispersers, kneaders, homogenizers, etc. can do. After completion of the reaction, the esterified fine cellulose fibers can be recovered as a dispersion or a dried product after being concentrated, washed, etc., if necessary.

The degree of modification of the chemically modified fine cellulose fiber (also referred to as chemically modified fine cellulose fiber) of the present embodiment is the average degree of substitution of hydroxyl groups (the average number of substituted hydroxyl groups per glucose, which is the basic constituent unit of cellulose, and DS. It is expressed as). In one embodiment, the DS of the chemically modified fine cellulose fiber is preferably 0.01 or more and 2.0 or less. When the DS is 0.01 or more, a resin composition containing chemically modified fine cellulose having a high thermal decomposition start temperature can be obtained. On the other hand, when it is 2.0 or less, an unmodified cellulose skeleton remains in the chemically modified fine cellulose, so that the chemistry has high tensile strength and dimensional stability derived from cellulose and a high thermal decomposition start temperature derived from chemical modification. A resin composition containing modified fine cellulose can be obtained. The DS is more preferably 0.05 or more, still more preferably 0.1 or more, particularly preferably 0.2 or more, most preferably 0.3 or more, still more preferably 1.8 or less, still more preferably 1. It is 5 or less, particularly preferably 1.2 or less, and most preferably 1.0 or less.

The degree of acyl substitution (DS) of the esterified fine cellulose fiber is calculated from the reflective infrared absorption spectrum of the esterified fine cellulose fiber based on the peak intensity ratio of the peak derived from the acyl group and the peak derived from the cellulose skeleton. be able to. The peak of the C = O absorption band based on the acyl group ^{appears at 1730 cm -1,} and the peak of the CO absorption band based on the cellulose skeleton chain appears at 1030 cm ^-1 (see FIG. 2). The DS of the esterified fine cellulose fiber is the DS obtained from the solid NMR measurement of the esterified fine cellulose fiber described later, and the absorption band of C = O based on the acyl group with respect to the peak intensity of the absorption band of the cellulose skeleton chain C—O. A correlation graph with the modification rate (IR index 1030) defined by the ratio of peak intensity was prepared, and the calibration curve substitution degree DS = 4.13 × IR index (1030) calculated from the correlation graph.
Can be obtained by using.

The DS of the esterified fine cellulose fiber by solid-state NMR is calculated ^{by performing 13} C solid-state NMR measurement on the freeze-crushed esterified fine cellulose fiber, and carbon C1-C6 derived from the pyranose ring of cellulose appearing in the range of 50 ppm to 110 ppm. It can be calculated by the following formula from the area intensity (Inf) of the signal assigned to one carbon atom derived from the modifying group with respect to the total area intensity (Inp) of the signal to which it belongs.
DS = (Inf) x 6 / (Inp)
For example, when the modifying group is an acetyl group, a signal of 23 ppm attributed to _{−CH 3 may be used.}
^{The conditions for the 13} C solid-state NMR measurement used are as follows, for example.
Equipment: Bruker Biospin Avance 500WB
Frequency: 125.77MHz
Measurement method: DD / MAS method
Waiting time: 75 sec
NMR sample tube: 4 mmφ
Accumulation number: 640 times (about 14 hours)
MAS: 14,500Hz
Chemical shift standard: Glycine (external standard: 176.03 ppm)

In esterified fine cellulose fibers, DS heterogeneity is defined by the ratio of the degree of modification (DSs) on the fiber surface to the degree of modification (DSt) of the entire fiber (which is synonymous with the above-mentioned degree of acyl substitution (DS)). The ratio (DSs / DSt) is preferably 1.05 or more. The larger the value of the DS non-uniform ratio, the more non-uniform structure like the sheath core structure (that is, the fiber surface layer is highly chemically modified while the fiber center retains the structure of cellulose that is close to the original unmodified structure. The structure) is remarkable, and while having high tensile strength and dimensional stability derived from cellulose, it leads to improvement of affinity with the resin during production of the resin composition and improvement of dimensional stability of the resin composition. The DS non-uniform ratio is more preferably 1.1 or more, more preferably 1.2 or more, further preferably 1.3 or more, particularly preferably 1.5 or more, most preferably 2.0 or more, and esterification fine. From the viewpoint of ease of producing cellulose fibers, the ratio is preferably 30 or less, more preferably 20 or less, still more preferably 10 or less.

The value of DSs varies depending on the degree of modification of the esterified fine cellulose fiber, but as an example, it is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and preferably 3 It is 0.0 or less, more preferably 2.5 or less, particularly preferably 2.0 or less, still more preferably 1.5 or less, particularly preferably 1.2 or less, and most preferably 1.0 or less. The preferred range of DSt is as described above for acyl substituents (DS).

In the esterified fine cellulose fiber, the smaller the coefficient of variation (CV) of the DS non-uniform ratio is, the smaller the variation in various physical properties of the resin composition is, which is preferable. The coefficient of variation is preferably 50% or less, more preferably 40% or less, still more preferably 30% or less, and most preferably 20% or less.

For the coefficient of variation (CV) of the DS non-uniform ratio, 100 g of an aqueous dispersion of esterified fine cellulose fibers (solid content of 10% by mass or more) was sampled and frozen and crushed by 10 g, which was used as a measurement sample, and 10 samples of DS were used. After calculating the DS non-uniform ratio from the DSs, the coefficient of variation is calculated from the standard deviation (σ) and the arithmetic mean (μ) of the DS non-uniform ratio among the obtained 10 samples.
DS non-uniform ratio = DSs / DS
Coefficient of variation (%) = standard deviation σ / arithmetic mean μ × 100

The calculation method of DSs is as follows. That is, the esterified fine cellulose fibers pulverized by freeze pulverization are placed on a dish-shaped sample table having a diameter of 2.5 mm, the surface is suppressed and flattened, and measurement is performed by X-ray photoelectron spectroscopy (XPS). The XPS spectrum reflects the constituent elements and the chemical bond state of only the surface layer of the sample (typically about several nm). Peak separation was performed on the obtained C1s spectrum, and the peak (289eV, CC bond) attributed to carbon C2-C6 derived from the pyranose ring of cellulose was assigned to one carbon atom derived from the modifying group with respect to the area intensity (Ipp). It can be calculated by the following formula from the area intensity (Ixf) of the peak to be formed.
DSs = (Ixf) x 5 / (Ixp)
For example, when the modifying group is an acetyl group, the C1s spectrum is peak-separated at 285 eV, 286 eV, 288 eV, and 289 eV, and then the peak of 289 ev is used for Ix and the O-C = O bond of the acetyl group is used for Ixf. A peak (286 eV) may be used.
The conditions for XPS measurement used are as follows, for example.
Equipment used: ULVAC-PHI VersaProbeII
Excitation source: mono. AlKα 15kV x 3.33mA
Analysis size: Approximately 200 μmφ
Photoelectron extraction angle: 45 °
Capture area Now scan: C 1s, O 1s
Pass Energy: 23.5eV

The fine cellulose fibers are washed and concentrated by filtration or centrifugation using water, and finally can be used for producing composite particles as a water slurry or a dried product.

Thermal decomposition temperature of the fine cellulose fibers (T _D), from the viewpoint of heat resistance and mechanical strength desired in-vehicle use or the like can be exhibited, and at 250 ° C. or higher in one aspect, preferably 265 ° C. or higher, more preferably It is 270 ° C. or higher, more preferably 275 ° C. or higher, particularly preferably 280 ° C. or higher, and most preferably 285 ° C. or higher. The higher the thermal decomposition start temperature is, the more preferable it is, but from the viewpoint of ease of producing fine cellulose fibers, it may be, for example, 320 ° C. or lower, or 300 ° C. or lower.

1% weight loss temperature of fine cellulose fibers (T _D), from the viewpoint of heat resistance and mechanical strength desired in-vehicle use or the like can be exhibited, and at 250 ° C. or higher in one aspect, preferably 265 ° C. or higher, more preferably Is 270 ° C. or higher, more preferably 275 ° C. or higher, particularly preferably 280 ° C. or higher, and most preferably 285 ° C. or higher. The higher the 1% weight loss temperature is, the more preferable it is, but from the viewpoint of ease of producing fine cellulose fibers, it may be, for example, 320 ° C. or lower, or 300 ° C. or lower.

The 250 ° C. weight change rate (T ₂₅₀ ) of the fine cellulose fiber is -10% or more, preferably -5% or more in one embodiment from the viewpoint of exhibiting the heat resistance and mechanical strength desired for in-vehicle use and the like. It is more preferably -4% or more, further preferably -3% or more, particularly preferably -2% or more, and most preferably -1% or more. The 250 ° C. weight change rate (T ₂₅₀ ) is preferably close to zero, but may be, for example, −0.1% or less, or −0.5% or less from the viewpoint of ease of producing fine cellulose fibers.

In this disclosure, the T _D, as shown in the illustration of FIG. 3, in the thermogravimetric (TG) analysis, the horizontal axis is the temperature, the vertical axis is a value determined from the weight residual ratio% Graph (Note, FIG. 3B is an enlarged view of FIG. 3A). Starting from the weight (weight loss of 0 wt%) of the fine cellulose fibers at 150 ° C. (with almost all water removed), the temperature continues to rise, and the temperature (T _1% ) and 2 wt% weight at the time of 1 wt% weight loss. Obtain a straight line through the decreasing temperature (T _2%). The temperature at the intersection of this straight line and the horizontal line (baseline) passing through the starting point of the weight loss amount of 0 wt% is defined _{as T D.}

The 1% weight loss temperature (T _1% ) is the temperature at which the weight is reduced by 1% by weight starting from the weight of 150 ° C. when the temperature is continuously raised by the method of _{T D.}

_{The 250 ° C. weight change rate (T 250 ° C.} ) of the fine cellulose fibers in the resin composition is the weight change rate when the fine cellulose fibers are held at 250 ° C. for 2 hours under a nitrogen flow in TG analysis.

<Amide compound>
The amide compound is a compound having one or more amide bonds (-C (= O) NH- bonds) in the molecule. The amide bond may be a peptide bond. The number of amide bonds in the molecule of the amide compound may be 1 or more, 2 or more, or 3 or more, and is preferably 100 or less, or 50 or less in that the amide compound is likely to be present in the vicinity of the fine cellulose fibers. The following, or 30 or less, or 10 or less.

The amide compound of the present disclosure is distinguished from a general polymer in that it is a low molecular weight compound, specifically, that it has a number average molecular weight of 10,000 or less.

From the viewpoint of chemical stability, the molecular weight of the amide compound is preferably 50 or more, 60 or more, or 70 or more, and it is easy to enter between the fine cellulose fibers and is excellent in the effect of improving the dispersibility of the fine cellulose fibers. In one embodiment, it is 10,000 or less, preferably 9000 or less, or 8000 or less, or 7000 or less, or 6000 or less, or 5000 or less, or 4000 or less, or 3000 or less, or 2000 or less, or 1000 or less. The above molecular weight is calculated by calculation from a chemical formula when the amide compound is a structure-defined low molecular weight compound, and when it is a polymer, it is dissolved in water and then gel permeation chromatography using water as a solvent. It is a value calculated by pullulan conversion by.

The amide compound may be an aliphatic or aromatic amide or a combination thereof. The amide compound preferably has an amide bond in the molecular skeleton (that is, a site other than the side chain) in that the effect of improving the dispersibility of the fine cellulose fibers is good. For example, a compound having a structure in which an amide bond is incorporated in the chain of an aliphatic or aromatic or a combination thereof in a hydrocarbon chain or at the molecular terminal is preferable. The number of carbon atoms in the hydrocarbon chain is preferably 2 or more, 3 or more, or 4 or more in that the chemical stability of the amide compound is good, and the fine cellulose fibers are easily dispersed between the fine cellulose fibers. It is preferably 24 or less, 18 or less, or 12 or less in that it is excellent in the property improving effect.

In one embodiment, the amide compound is a compound having no repeating unit or having a repeating unit and having a repeating number of 2 to 100 in that the amide compound easily penetrates between the fine cellulose fibers and is excellent in the effect of improving the dispersibility of the fine cellulose fibers. Is a compound (ie, an oligomer, or a polymer with a small number of repeats). The number of repetitions is preferably 2 or more, 3 or more, or 4 or more, and preferably 50 or less, 30 or less, or 20 or less, or 10 or less.

The amide compound is preferably a cyclic amide, more preferably a 3- to 7-membered cyclic amide, and even more preferably a pyrrolidone (that is, a 5-membered ring) because it easily penetrates between the fine cellulose fibers and is excellent in the effect of improving the dispersibility of the fine cellulose fibers. ), Laurolactam (ie, 6-membered ring) or caprolactam (ie, 7-membered ring cyclic amide), particularly preferably caprolactam. These lactams can be obtained as commercial products, and may be used alone or in combination of two or more.

The amide compound is preferable because it easily penetrates between the fine cellulose fibers and has an excellent effect of improving the dispersibility of the fine cellulose fibers.
NH ₂ CO-R ^1- CONH ₂
(In the formula, R ¹ is a divalent group that is an aliphatic or aromatic or a combination thereof.)
It is a diamide represented by. R ¹ is preferably a C _{2 to} C ₈ group, more preferably a C _{2 to} C ₈ aliphatic group, still more preferably a C _{2 to} C ₆ aliphatic group, and particularly preferably a C ₄ aliphatic group. be. A particularly preferred amide compound is adipamide.

The amide compound is preferably water-soluble. Specifically, the amount of the amide compound dissolved in 100 g of water at 25 ° C. is preferably 1 g or more, 5 g or more, or 10 g or more. By mixing such a compound with the fine cellulose fibers, for example, in the state of an aqueous solution, the amide compound can be allowed to enter between the fine cellulose fibers, and the dispersibility of the fine cellulose fibers can be remarkably improved. The amount of the amide compound dissolved in 100 g of water at 25 ° C. is not particularly limited, but is preferably 100 g or less, or 80 g or less, from the viewpoint of suppressing moisture absorption of the resin composition and suppressing deterioration of physical properties under high humidity conditions. Or 50 g or less.

As the amide compound, a water-soluble polyamide (also referred to as a water-soluble polyamide) may be used. Examples of the water-soluble polyamide include polyamides having a structure such as a sulfonic acid group, an alkali metal salt of a sulfonic acid, a secondary amine, a tertiary amine, and an alkyleneoxy group in the molecule. The water-soluble polyamide can be produced by using a monomer which is a water-soluble component at the time of polymerization.

Examples of the monomer having a sulfonic acid group or the monomer which is a sulfonate include sodium 2,5- or 3,5-dicarboxybenzenesulfonate, sodium 2,5- or 3,5-diaminomethylbenzenesulfonate, 5 − Examples thereof include dimethyl sodium sulfoisophthalate.

Examples of the monomer containing a secondary amine structure in the main chain include the following formula:
H ₂ N- (R ^1- NH) _m- R ^1- NH ₂
(In the formula, R ¹ represents the alkylene group of C ₂ or C ₃ , and m is an integer of 2-10.)
The alkyleneamines represented by (1) can be exemplified, and more specifically, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like can be exemplified.

Examples of the monomer containing a tertiary amine structure in the main chain include N- (2-aminoethyl) piperazine and 1,4-bis (3-aminopropyl) piperazine.

Examples of the monomer containing a tertiary amine structure in the side chain include α-dimethylaminoε-caprolactam.

Examples of the monomer containing an alkyleneoxy group in the main chain include the following formula:
H ₂ N-R ^3- O- (R ^2- O) _n- R ^3- NH ₂ , or HOOC-R ^3- O- (R ^2- O) _n- R ^3- COOH
(In the formula, R ² represents the alkylene group of C _{1 to} C ₈ ^{, R 3} represents the alkylene group of C ₂ or C ₃ , and n is an integer from 0 to 200.)
Examples thereof include diamines and dicarboxylic acids represented by.

When diamine is used as the water-soluble monomer, it is preferable to use it in combination with substantially the same molar amount of dicarboxylic acid. Examples of the dicarboxylic acid include adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid and the like. When a dicarboxylic acid is used as the water-soluble monomer, it is preferable to use it in combination with substantially the same molar amount of diamine. Examples of diamines include aliphatic diamines such as hexamethylenediamine, alicyclic diamines such as paraaminocyclohexylmethane, and aromatic diamines such as m-xylylenediamine.

When a diamine and a dicarboxylic acid are used, it is generally convenient to use them as a salt obtained by reacting both components in substantially the same molar amount.

Here, substantially this mole will be described. As the ratio of the number of moles of diamine and dicarboxylic acid deviates from 1, the polymerization rate tends to decrease and the degree of polymerization tends to decrease. Therefore, the actual mole is a range in which these effects are not substantially observed, and the degree of deviation is usually such that the number of moles of dicarboxylic acid is ± 10% or less of the number of moles of diamine. ..

For example, a water-soluble monomer containing a cyclic amide such as ε-caprolactam can be polymerized by ring-opening polymerization using an acid or a base.

The water-soluble monomer may be polymerized alone, but in many cases, it is often copolymerized with another monomer in order to balance with water-soluble or other physical properties. As the copolymerization component, lactams such as ε-caprolactam, amino acids such as aminocaproic acid, the above-mentioned dicarboxylic acids, diamines and the like are used.

The amide compound preferably has high hygroscopicity. Specifically, the hygroscopicity of the amide compound at 23 ° C. and 60% RH (that is, the mass ratio of water to 100% by mass of the amide compound) is preferably 10% or more, 20% or more, or 30% or more. Is. By mixing such a compound with the fine cellulose fibers, water can be attracted between the fine cellulose fibers, so that it is possible to prevent the fine cellulose fibers from sticking to each other due to hydrogen bonds during drying, and the fine cellulose fibers can be dispersed. The sex can be remarkably improved. The hygroscopicity of the amide compound at 23 ° C. and 60% RH is not particularly limited, but is preferably 1000% or less, or 1000% or less, from the viewpoint of suppressing the hygroscopicity of the resin composition and suppressing the deterioration of physical properties under high humidity conditions. It is 500% or less, or 300% or less, or 200% or less, or 100% or less.

The moisture absorption rate is such that 0.5 g of glass fiber is added to 10 g of a 1 mass% solution of an amide compound, dried in an oven, completely dried under vacuum conditions (120 ° C., 2 hr), and then humidity-controlled at 23 ° C. and 60% RH. It is the equilibrium moisture content (%) obtained. In this method, the moisture absorption of the glass fiber is 0, and all the weight increase can be considered to be due to the moisture absorption of the amide compound.

The higher the heat resistance of the amide compound, the more preferable it is because the yellowing of the resin composition obtained by combining with the resin is suppressed. The index of heat resistance is the change (ΔYI) in the degree of yellowing (YI value) of the amide compound before and after the heat treatment, preferably 30 or less, 20 or less, or 10 or less, or 5 or less. The heat treatment conditions were such that the amide compound was heated in an oven at 190 ° C. for 4 hours in a nitrogen atmosphere, and the degree of yellowing was a reflection type (SCI + SCE) using a spectrocolorimeter (for example, CM-700d manufactured by Konica Minolta). , Measure under the condition of measurement diameter of 3 mm. The change in yellowing degree (ΔYI) is a value obtained by subtracting the YI value before the heat treatment from the YI value after the heat treatment. The smaller ΔYI is, the more preferable, but from the viewpoint of availability of the amide compound, in one embodiment, it may be 0.1 or more, 0.5 or more, or 1 or more.

In one embodiment, the amide compound is preferably a compound other than a salt of a compound having an amino group and a carboxy group at the terminals. This is because such salts tend to exhibit yellowing or other coloring. Further, in one embodiment, the amide compound is preferably a compound other than an amino acid derivative. This is because the amino acid derivative tends to easily form a hydrogen bond due to the tendency for the concentration of the amide group, the amino group and / or the carboxy group (acid type or salt type) in the compound to be high. In one embodiment, the amide compounds, carboxylate anion (-COO ^-) or no site, or has a carboxylate anion moiety, an amide bond closest with the carboxylate anionic sites (-C (= O ) N (H)-) is a compound having a structure in which the C side is closer to the carboxylate anion site than the N side. The carboxylate anionic moiety can typically be an anionic group in the salt.

When the amide compound has a plurality of amide bonds, the amide bonds tend to form hydrogen bonds, so that the amide bonds are separated by a chain composed of C and / or O by 3 or more elements or 5 or more elements. Is preferable.

The melting point of the amide compound is preferably 300 ° C. or lower, or 250 ° C. or lower, or 230 ° C. or lower, or 200 ° C. or lower, or 180 ° C. or lower, or 150 ° C. or lower. By mixing such a compound with the fine cellulose fibers in a molten state, for example, the amide compound can be allowed to enter between the fine cellulose fibers and the dispersibility of the fine cellulose fibers can be remarkably improved. There is no particular lower limit to the melting point of the amide compound, but from the viewpoint of suppressing bleeding from the resin composition, it is preferably solid at the operating temperature, and specifically, the melting point is preferably −30 ° C. or higher, or −. 20 ° C or higher, or -10 ° C or higher, or 0 ° C or higher, or 10 ° C or higher, or 20 ° C or higher, or 30 ° C or higher, or 40 ° C or higher. The melting point is a value measured by a method of reading the peak top of a melting peak in differential scanning calorimetry (DSC).

In fine cellulose fibers in which cellulose is finely divided to the nanometer level, the surface area becomes significantly large, so that the surfaces of cellulose undergo hydrogen bond-based interactions. When these fine cellulose fibers are dried and powdered, extremely strong drying shrinkage occurs, and the shrinkage structure is irreversible. Further, since the hydrophilic property of cellulose appears remarkably in the fine cellulose fiber, the fine cellulose fiber undergoes vigorous aggregation under a different medium such as a resin. When the amide compound of the present disclosure is present, the fine cellulose fibers can be satisfactorily redispersed even from a dry state, so that the fine cellulose fibers can be redispersed in the resin by melt-kneading with the resin. can. The fine cellulose fibers highly dispersed in the resin improve various mechanical characteristics of the resin composition.

Considering the production process of the composite material containing the filler and the resin, it is extremely significant that the composite particles as the filler are in a dry state. It was difficult to obtain as a redispersible dry matter. In the composite particles according to one aspect of the present disclosure, the amide compound interacts with the surface of the fine cellulose fibers to enable a high degree of redispersion of the fine cellulose fibers in the resin.

The ratio of the fine cellulose fibers to 100% by mass of the composite particles is preferably 10% by mass or more, 20% by mass or more, or 30% by mass or more, or 40% by mass or more from the viewpoint of obtaining a good action as a filler. , 50% by mass or more, or 60% by mass or more, or 70% by mass or more, or 80% by mass or more, and is preferable from the viewpoint of satisfactorily obtaining the effect of improving the dispersibility of the fine cellulose fibers by using the amide compound. It is 99% by mass or less, 95% by mass or less, or 90% by mass or less.

The ratio of the amide compound to 100% by mass of the composite particles is preferably 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass from the viewpoint of obtaining a good effect of improving the dispersion of the fine cellulose fibers. % Or more, or 20% by mass or more, and preferably 90% by mass or less, or 80% by mass or less, or 70% by mass or less, or 60% by mass from the viewpoint of obtaining a good filler action by using fine cellulose fibers. Below, or 50% by mass or less, or 40% by mass or less.

The ratio of the amide compound to 100 parts by mass of the fine cellulose fibers in the composite particles is preferably 1 part by mass to 1000 parts by mass, 1 part by mass to 500 parts by mass, or 5 parts by mass to 200 parts by mass, or 10 parts by mass. Parts to 100 parts by mass, 15 parts by mass to 80 parts by mass, 20 parts by mass to 70 parts by mass, or 25 parts by mass to 50 parts by mass.

<Additional ingredients>
The composite particles may further contain additional components as needed to improve its performance. The additional components are not particularly limited, but are, for example, fine fibers other than fine cellulose fibers (for example, fibrillated fibers of aramid fibers, cellulose whiskers); compatibilizers; plasticizers; polysaccharides such as starches and alginic acid; gelatin. , Nikawa, natural proteins such as casein; inorganic compounds such as zeolite, ceramics, talc, silica, metal oxides, metal powders; colorants; fragrances; pigments; flow conditioners; leveling agents; conductive agents; antistatic agents; ultraviolet rays Absorbents; ultraviolet dispersants; deodorants; surfactants and the like.

The presence of the cellulose whiskers in the composite particles improves the dispersibility of the composite particles in water or in the resin composition, resulting in improved mechanical properties of the resin composition. The main properties of cellulose whiskers are, but not limited to, L / D of 1 or more and less than 30, preferably L / D = 1-20, more preferably L / D = 1-10. be. The crystallinity of the cellulose whiskers is, for example, 70% or more, preferably 80% or more, and may be 99% or less, for example. The degree of polymerization of the cellulose whiskers is, for example, 1000 or less, or 750 or less, or 500 or less, or 350 or less, or 300 or less, or 250 or less, or 200, and may be, for example, 10 or more, or 20 or more. The cellulose whiskers may be commercially available products, or may be obtained by cutting wood pulp and hydrolyzing it in an aqueous hydrochloric acid solution, for example. Each characteristic value of the cellulose whiskers can be measured for the fine cellulose fibers by the same method as described above.

The above-mentioned surfactant has a function of enhancing the dispersibility of the composite particles in water or a resin composition described later. Surfactants need only have a chemical structure in which a site having a hydrophilic substituent and a site having a hydrophobic substituent are covalently bonded, and are used in various applications such as edible and industrial purposes. Can be used. For example, the following can be used alone or in combination of two or more.
As the surfactant, any of anionic surfactants, nonionic surfactants, amphoteric ionic surfactants, and cationic surfactants can be used, but they have an affinity for cellulose. In that respect, anionic surfactants and nonionic surfactants are preferable, and nonionic surfactants are more preferable.

Among the above, a surfactant having a polyoxyethylene chain, a carboxylic acid group, or a hydroxyl group as a hydrophilic group is preferable, and a polyoxyethylene-based surfactant having a polyoxyethylene chain as a hydrophilic group is preferable in terms of affinity with cellulose. Agents (polyoxyethylene derivatives) are more preferred, and nonionic polyoxyethylene derivatives are even more preferred. The polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, further preferably 10 or more, and particularly preferably 15 or more. The longer the chain length, the higher the affinity with cellulose. However, in terms of the balance with the coating property, the upper limit is preferably 60 or less, more preferably 50 or less, further preferably 40 or less, and particularly preferably 30 or less. 20 or less is most preferable.

Among the above-mentioned surfactants, as hydrophobic groups, alkyl ether type, alkyl phenyl ether type, rosin ester type, bisphenol A type, β naphthyl type, styrenated phenyl type, and cured castor oil type have an affinity with the resin. Since it has high properties, it can be preferably used. As a preferable alkyl chain length (in the case of alkylphenyl, the number of carbon atoms excluding the phenyl group), the carbon chain is preferably 5 or more, more preferably 10 or more, further preferably 12 or more, and particularly preferably 16 or more. When the resin is polyolefin, the higher the number of carbon atoms, the higher the affinity with the resin, so there is no upper limit, but the upper limit is preferably 30 or less, more preferably 25 or less.

Among these hydrophobic groups, those having a cyclic structure or those having a bulky and polyfunctional structure are preferable. The alkylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, and styrenated phenyl type are preferable as those having a cyclic structure, and the cured castor oil type is preferable as those having a polyfunctional structure.
Of these, the rosin ester type and the cured castor oil type are particularly preferable.

The content of any additional component in the composite particle is appropriately selected as long as the desired effect of the present invention is not impaired, and is, for example, 0.01 to 50% by mass, or 0.1 to 30% by mass. It may be there.

Although it depends on the type of resin, an organic compound having a boiling point of 160 ° C. or higher may be effective as a nonionic surfactant-based dispersion medium. As a specific example of such an organic compound, for example, when the resin is a polyolefin resin, a high boiling point organic solvent such as liquid paraffin or decalin is effective. When the resin is a polar resin such as a nylon resin or a polyacetal resin, it is effective to use a solvent similar to the aprotic solvent that can be used when producing fine cellulose fibers, for example, DMSO. In some cases.

≪Manufacturing of composite particles≫
The method for producing the composite particle is not particularly limited, and examples thereof include the following methods. According to these methods, the composite particles can be recovered as a slurry or a dried product.
(1) A method in which a slurry of fine cellulose fibers (for example, an aqueous dispersion or an organic solvent dispersion) and an amide compound are mixed and then optionally dried (that is, powdered) to recover composite particles.
(2) A step of adding an amide compound to an organic solvent dispersion of fine cellulose fibers to obtain an organic solvent dispersion in which the fine cellulose fibers are dispersed and the amide compound is dissolved.
A step of mixing this organic solvent dispersion with a poor solvent of an amide compound and precipitating the amide compound (that is, precipitating composite particles containing fine cellulose fibers and the amide compound) to obtain a composite particle dispersion.
Optional steps of separating and recovering composite particles by filtration, centrifugation, etc., washing with pure water, and / or drying,
How to include.
(3) A method in which an amide compound is added and dissolved in the process of producing fine cellulose fibers, and after the production of fine cellulose fibers is completed, the precipitation step and subsequent steps are performed in the same manner as in the above method (2).

The fine cellulose fibers are subjected to a defibration step of defibrating cellulose in an organic solvent to obtain a fine cellulose fiber dispersion, and optionally a purification step of substituting the organic solvent in the fine cellulose fiber dispersion with water. It can be preferably prepared. The addition of the amide compound in the method (3) above may be carried out before or during defibration.

When chemically modifying the fine cellulose fibers, it is preferable to provide a chemical modification step for chemically modifying the fine cellulose fibers at the same time as the defibration step or after the defibration step (preferably before the purification step).

In the production of composite particles, contacting the fine cellulose fibers with the amide compound in the presence of a liquid medium (water, organic solvent, etc.) is advantageous in that the polyamide compound can be uniformly and satisfactorily fixed to the fine cellulose fibers. ..

The organic solvent in which the amide compound is dissolved is not particularly limited, but alcohols, ethers, benzene and the like are suitable. The solvent may be one kind of compound or a mixed solvent in which a plurality of compounds are mixed. Specific examples thereof include ethanol and acetone.

When the defibration and / or chemical modification of the cellulose raw material and the addition of the amide compound are carried out simultaneously or continuously in an organic solvent, DMSO, DMF, DMAc, NMP and the like, particularly DMSO, may be used. In this case, fine cellulose fibers having a high thermal decomposition start temperature can be produced more efficiently. The mechanism of action is not always clear, but it is presumed to be due to the homogeneous microswelling of the cellulose raw material in the aprotic solvent.

The stirring or shearing method required to promote the compounding of the fine cellulose fibers with the amide compound is not particularly limited, but for example, a device to which collision shearing is applied, such as a planetary ball mill and a bead mill. Use a device that adds a rotary shear field that induces fibrillation of cellulose, such as a disc refiner and grinder, or a device that can perform mixing, stirring, and dispersing functions with high efficiency, such as various kneaders and planetary mixers. Can be done.

Conventionally, the process of concentrating a slurry of fine cellulose fibers takes a very long time due to clogging, for example when using a filtration operation. Therefore, the productivity when performing multiple washings was remarkably low. However, in the above-mentioned production methods ((2) and (3)) in which washing and concentration are carried out after precipitating the amide compound using a poor solvent, the fine cellulose fibers and the amide compound are both precipitated. While the filterability is extremely improved and the time required for the concentration step can be significantly shortened, the cleaning efficiency is equal to or higher than that of the conventional one.

The composite particles are obtained by mixing, washing and concentrating operations, and containing water or an organic solvent. The liquid fraction in the composite particles is preferably 30% by mass or less, or 20% by mass or less, or 10% by mass or less, or 8% by mass or less, or 5% by mass or less, or 3% by mass or less, or 1% by mass. It can be controlled to% or less. It is desirable that the liquid fraction is low, but from the viewpoint of ease of producing composite particles, for example, it may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more. The drying operation may be appropriately carried out so that the liquid fraction in the composite particles is within a desired range. The dryer is not particularly limited, but even a high-viscosity mixer such as a kneader, a planetary mixer, a propeller mixer, a ribbon mixer, a single-screw or biaxial screw extruder, or a Banbury mixer can be easily stirred and kneaded. Mixer is preferable. The drying conditions may be either atmospheric pressure or reduced pressure, and the drying temperature is preferably 200 ° C. or lower in order to prevent thermal deterioration of the fine cellulose fibers.

In one embodiment, in the composite particles containing the cyclic amide as the amide compound, the cyclic amide can be ring-opened and polymerized by heating in an inert atmosphere, for example, to obtain a polyamide. In this case, it is preferable that the composite particles further contain an alkali catalyst or an acid catalyst and, if necessary, a polymerization initiator, or the composite particles are mixed with an alkali catalyst or an acid catalyst and optionally a polymerization initiator. For example, after separately preparing the cyclic amide and other constituents of the composite particles, they may be mixed to form composite particles and ring-opening polymerization of the cyclic amide.

≪Resin composition≫
One aspect of the present invention provides a resin composition containing the above-mentioned composite particles and a resin. As the resin, a thermoplastic resin, a thermosetting resin, a photocurable resin, an elastomer and the like can be used.

<Thermoplastic resin>
Specific examples of the thermoplastic resin are not particularly limited, but are, for example, polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymer; vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride; Vinyl-based resins such as polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol; polyacetal-based resin; fluororesins such as polyvinylidene fluoride; polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene, Polystyrene resins such as styrene-butadiene block copolymers and styrene-isoprene block copolymers; nitrile resins such as polyacrylonitrile, styrene-acrylonitrile copolymers and ABS resins; polyphenylene ether resins; polyamides; polyurethanes; polyimides; polyamides Iimide; Acrylic resins such as polymethacrylic acid and polyacrylic acid; Polycarbonate; Polyphenylene sulfide; Polysulphon; Polyethersulphon; Polyethernitrile; Polyetherketone; Polyketone; Liquid crystal polymer; Silicone resin; Ionomer; Cellulose (wood pulp, cotton) Natural celluloses such as; regenerated celluloses such as biscous polymers, copper ammonia polymers and Tencel); cellulose derivatives such as nitrocellulose and cellulose acetate. These thermoplastic resins may be used alone or in a blend of two or more. The blending ratio at the time of blending may be appropriately selected according to various uses.

Among thermoplastic resins, crystalline resins having a melting point in the range of 100 ° C. to 350 ° C., or amorphous resins having a glass transition temperature in the range of 100 ° C. to 250 ° C., for example, polyolefin resins and polyamide resins. , Polyester resin, polyacetal resin, polyphenylene ether resin, polyphenylene sulfide resin and a mixture of two or more of them are preferably mentioned, and more preferably from the viewpoint of handleability and cost, polyolefin resin, polyamide resin, polyester. Examples thereof include based resins and polyacetal resins. The melting point of the thermoplastic resin (particularly the crystalline resin) is preferably 140 ° C. or higher, 150 ° C. or higher, or 160 ° C. or higher, or 170 ° C. or higher, or 180 ° C. or higher from the viewpoint of enhancing the heat resistance of the resin composition. , 190 ° C. or higher, or 200 ° C. or higher, or 210 ° C. or higher, 220 ° C. or higher, or 230 ° C. or higher, or 240 ° C. or higher, or 245 ° C. or higher, or 250 ° C. or higher.

The melting point of the thermoplastic resin is, for example, for a resin having a relatively low melting point (for example, a polyolefin resin), 150 ° C. to 190 ° C., or 160 ° C. to 180 ° C., for example, a resin having a relatively high melting point (for example, a polyamide resin). Can be exemplified with respect to 220 ° C. to 350 ° C. or 230 ° C. to 320 ° C.

The melting point of the crystalline resin referred to here is the peak top temperature of the endothermic peak that appears when the temperature is raised from 23 ° C. to 10 ° C./min using a differential scanning calorimetry device (DSC). When two or more endothermic peaks appear, it means the peak top temperature of the endothermic peak on the highest temperature side. The enthalpy of the endothermic peak at this time is preferably 10 J / g or more, and more preferably 20 J / g or more. In the measurement, it is desirable to use a sample in which the sample is once heated to a temperature condition of melting point + 20 ° C. or higher, the resin is melted, and then cooled to 23 ° C. at a temperature lowering rate of 10 ° C./min.

The glass transition temperature of the amorphous resin referred to here is when measured at an applied frequency of 10 Hz while raising the temperature from 23 ° C. to 2 ° C./min using a dynamic viscoelasticity measuring device. The temperature at the peak of the peak where the storage elastic modulus is greatly reduced and the loss elastic modulus is maximized. When two or more peaks of loss elastic modulus appear, it means the peak top temperature of the peak on the highest temperature side. The measurement frequency at this time is preferably at least once every 30 seconds in order to improve the measurement accuracy. The method for preparing the sample for measurement is not particularly limited, but from the viewpoint of eliminating the influence of molding strain, it is desirable to use a cut piece of a hot press molded product, and the size (width and thickness) of the cut piece can be as large as possible. The smaller one is preferable from the viewpoint of heat conduction.

A preferred polyolefin resin as a thermoplastic resin is a polymer obtained by polymerizing olefins (for example, α-olefins) and alkenes as a monomer unit. Specific examples of the polyolefin resin include ethylene-based (co) polymers such as low-density polyethylene (for example, linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, and ultra-high-molecular-weight polyethylene, polypropylene, and ethylene. Polypropylene-based (co) polymers such as −propylene copolymer, ethylene-propylene-diene copolymer, etc., ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-glycidyl methacrylate copolymer Examples thereof include copolymers of α-olefins such as ethylene represented by coalescence and the like.

Here, polypropylene is mentioned as the most preferable polyolefin resin. In particular, polypropylene having a melt mass flow rate (MFR) of 3 g / 10 minutes or more and 30 g / 10 minutes or less measured at 230 ° C. and a load of 21.2 N in accordance with ISO1133 is preferable. The lower limit of MFR is more preferably 5 g / 10 min, even more preferably 6 g / 10 min, and most preferably 8 g / 10 min. The upper limit is more preferably 25 g / 10 minutes, even more preferably 20 g / 10 minutes, and most preferably 18 g / 10 minutes. It is desirable that the MFR does not exceed the above upper limit value from the viewpoint of improving the toughness of the composition, and it is desirable that the MFR does not exceed the above lower limit value from the viewpoint of the fluidity of the composition.

Further, in order to enhance the affinity with cellulose, an acid-modified polyolefin resin can also be preferably used. The acid at this time can be appropriately selected from maleic acid, fumaric acid, succinic acid, phthalic acid, anhydrides thereof, and polycarboxylic acids such as citric acid. Of these, maleic acid or an anhydride thereof is preferable because of the ease of increasing the denaturation rate. The modification method is not particularly limited, but a method of heating to a melting point or higher and melt-kneading in the presence or absence of a peroxide is common. As the acid-modified polyolefin resin, all of the above-mentioned polyolefin-based resins can be used, but polypropylene is particularly preferable. The acid-modified polypropylene may be used alone, but it is more preferable to use it in combination with unmodified polypropylene in order to adjust the modification rate of the resin as a whole. The ratio of the acid-modified polypropylene to all polypropylene at this time is 0.5% by mass to 50% by mass. A more preferable lower limit is 1% by mass, still more preferably 2% by mass, even more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass. The upper limit is more preferably 45% by mass, still more preferably 40% by mass, even more preferably 35% by mass, particularly preferably 30% by mass, and most preferably 20% by mass. In order to maintain the interfacial strength between the resin and cellulose, the lower limit or more is preferable, and in order to maintain the ductility of the resin, the upper limit or less is preferable.

The melt mass flow rate (MFR) measured at 230 ° C. and a load of 21.2 N in accordance with ISO 1133 of acid-modified polypropylene is preferably 50 g / 10 minutes or more in order to enhance the affinity with the cellulose interface. .. A more preferable lower limit is 100 g / 10 minutes, even more preferably 150 g / 10 minutes, and most preferably 200 g / 10 minutes. There is no particular upper limit, but it is 500 g / 10 minutes from the maintenance of mechanical strength. By setting the MFR within this range, it is possible to enjoy the advantage that it easily exists at the interface between the cellulose and the resin.

Examples of preferable polyamide-based resins as thermoplastic resins include polyamide 6, polyamide 11, polyamide 12 obtained by a polycondensation reaction of lactams, 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, and the like. 1,7-Heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonandiamine, 2-methyl-1,8- Diamines such as octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylene diamine, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid , Octanedioic acid, nonanedioic acid, decanedioic acid, benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1,4 dicarboxylic acid, etc., cyclohexane-1,3-dicarboxylic acid, cyclohexane Polyamides 6,6, polyamides 6,10, polyamides 6,11, polyamides 6,12, polyamides 6, T, polyamides 6, I, and polyamides obtained as copolymers with dicarboxylic acids such as -1,4-dicarboxylic acids. 9, T, polyamide 10, T, polyamide 2M5, T, polyamide MXD, 6, polyamide 6, C, polyamide 2M5, C, and copolymers obtained by copolymerizing these, as an example, polyamide 6, T / 6, Examples thereof include a copolymer such as I.

Among these polyamide-based resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6, 6, polyamide 6, 10, polyamide 6, 11, polyamide 6, 12 and polyamide 6, C, polyamide 2 M5, C The alicyclic polyamide such as is more preferable.

The concentration of the terminal carboxyl group of the polyamide resin is not particularly limited, but the lower limit is preferably 20 μmol / g, more preferably 30 μmol / g. The upper limit of the terminal carboxyl group concentration is preferably 150 μmol / g, more preferably 100 μmol / g, and further preferably 80 μmol / g.

In the polyamide resin, the ratio of carboxyl terminal groups to total terminal groups ([COOH] / [total terminal groups]) is more preferably 0.30 to 0.95. The lower limit of the carboxyl-terminal group ratio is more preferably 0.35, even more preferably 0.40, and most preferably 0.45. The upper limit of the carboxyl-terminal group ratio is more preferably 0.90, even more preferably 0.85, and most preferably 0.80. The carboxyl-terminal group ratio is preferably 0.30 or more from the viewpoint of dispersibility of the cellulose fiber in the composition, and is preferably 0.95 or less from the viewpoint of the color tone of the obtained composition.

As a method for adjusting the terminal group concentration of the polyamide resin, a known method can be used. For example, a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, a monoalcohol, etc. Examples thereof include a method of adding a terminal modifier that reacts with an terminal group to the polymerization solution.

Examples of the terminal modifier that reacts with the terminal amino group include acetic acid, propionic acid, butylic acid, valeric acid, caproic acid, capric acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutylic acid. And other aliphatic monocarboxylic acids; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid. Carboxylic acids; and a plurality of mixtures arbitrarily selected from these. Among these, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, etc. One or more end regulators selected from the group consisting of benzoic acid and benzoic acid are preferable, and acetic acid is most preferable.

Examples of the terminal modifier that reacts with the terminal carboxyl group include aliphatic groups such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine and dibutylamine. Monoamines; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine and any mixtures thereof. Among these, one or more terminals selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine and aniline from the viewpoints of reactivity, boiling point, stability of sealing terminal, price and the like. Regulators are preferred.

The concentrations of these amino-terminal groups and carboxyl-terminal groups are preferably obtained by ¹ H-NMR from the integrated value of the characteristic signal corresponding to each terminal group in terms of accuracy and simplicity. As a method for determining the concentration of these terminal groups, specifically, the method described in JP-A-7-228775 is recommended. When this method is used, ditrifluoroacetic acid is useful as the measurement solvent. In addition, the ^{number of integrations of 1 1} H-NMR requires at least 300 scans even when measured with an instrument having sufficient resolution. In addition, the concentration of the terminal group can also be measured by a measurement method by titration as described in JP-A-2003-055549. However, in order to reduce the influence of mixed additives, lubricants, etc. as much as possible, ¹ H-NMR quantification is more preferable.

The polyamide resin has an intrinsic viscosity [η] measured in concentrated sulfuric acid at 30 ° C., preferably 0.6 to 2.0 dL / g, and preferably 0.7 to 1.4 dL / g. Is more preferable, 0.7 to 1.2 dL / g is further preferable, and 0.7 to 1.0 dL / g is particularly preferable. When the above-mentioned polyamide having an intrinsic viscosity in a preferable range, particularly preferably a range, is used, it is possible to give the effect of significantly increasing the fluidity in the mold during injection molding of the resin composition and improving the appearance of the molded piece. can.

In the present disclosure, "intrinsic viscosity" is synonymous with viscosity generally called intrinsic viscosity. A specific method for determining this viscosity is to measure ηsp / c of several measuring solvents having different concentrations under a temperature condition of 30 ° C. in 96% concentrated sulfuric acid, and to measure the respective ηsp / c and the concentration (c). ) Is derived, and the concentration is extrapolated to zero. The value extrapolated to zero is the intrinsic viscosity.
These details are described, for example, on pages 291 to 294 of Prentice Process Engineering (Prentice-Hall, Inc. 1994).
At this time, it is desirable from the viewpoint of accuracy that the score of some measuring solvents having different concentrations is at least 4. At this time, the recommended concentrations of the different viscosity measuring solutions are preferably at least 4 points of 0.05 g / dL, 0.1 g / dL, 0.2 g / dL, and 0.4 g / dL.

Preferred polyester-based resins as thermoplastic resins include polyethylene terephthalate (hereinafter, may be simply referred to as PET) and polybutylene succinate (polyester resin composed of an aliphatic polyvalent carboxylic acid and an aliphatic polyol (hereinafter, unit PBS). (Sometimes referred to as), polybutylene succinate adipate (hereinafter, also simply referred to as PBSA), polybutylene adipate terephthalate (hereinafter, also simply referred to as PBAT), polyhydroxyalkanoic acid (3-hydroxyalkanoic acid). Polyester resin composed of: PHA (hereinafter, may be simply referred to as PHA), polylactic acid (hereinafter, may be simply referred to as PLA), polybutylene terephthalate (hereinafter, may be simply referred to as PBT), polyethylene naphthalate (hereinafter, may be simply referred to as PBT). , One or more selected from polyarylate (hereinafter, also simply referred to as PAR), polycarbonate (hereinafter, sometimes simply referred to as PC), etc. may be used. can.

Among these, more preferable polyester-based resins include PET, PBS, PBSA, PBT, and PEN, and more preferably, PBS, PBSA, and PBT.

Further, in the polyester resin, the terminal group can be freely changed depending on the monomer ratio at the time of polymerization and the presence / absence and amount of the terminal stabilizer added, but the carboxyl terminal group with respect to all the terminal groups of the polyester resin can be freely changed. More preferably, the ratio ([COOH] / [all end groups]) is 0.30 to 0.95. The lower limit of the carboxyl-terminal group ratio is more preferably 0.35, even more preferably 0.40, and most preferably 0.45. The upper limit of the carboxyl-terminal group ratio is more preferably 0.90, even more preferably 0.85, and most preferably 0.80. The carboxyl-terminal group ratio is preferably 0.30 or more from the viewpoint of dispersibility of the cellulose fiber in the composition, and is preferably 0.95 or less from the viewpoint of the color tone of the obtained composition.

Preferable polyacetal resins as thermoplastic resins are generally homopolyacetal made from formaldehyde and copolyacetal containing trioxane as a main monomer and 1,3-dioxolan as a comonomer component, and both can be used. However, from the viewpoint of thermal stability during processing, copolyacetal can be preferably used. In particular, the amount of the structure derived from the comonomer component (for example, 1,3-dioxolane) is more preferably in the range of 0.01 to 4 mol%. The preferable lower limit of the amount of the structure derived from the comonomer component is 0.05 mol%, more preferably 0.1 mol%, and even more preferably 0.2 mol%. The upper limit is preferably 3.5 mol%, more preferably 3.0 mol%, even more preferably 2.5 mol%, and most preferably 2.3 mol%.

From the viewpoint of thermal stability during extrusion and molding, it is desirable that the lower limit is within the above range, and from the viewpoint of mechanical strength, the upper limit is preferably within the above range.

As the thermoplastic resin, a resin having a hydrophilic group (for example, one or more selected from a hydroxyl group, an amino group and a carboxy group) is particularly preferable in that it has a good affinity with an amide compound. A preferred example of the thermoplastic resin having a hydrophilic group is selected from the group consisting of an acid-modified polyolefin resin, a polyacetal resin, a polycarbonate resin, a polyamide resin, a polyester resin, a polyphenylene ether resin, and an acrylic resin. One or more types. Of these, polyamide-based resins and maleated polypropylene are preferable.

<Thermosetting resin>
Specific examples of the thermosetting resin are not particularly limited, but for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, and bisphenol M type epoxy resin. , Bisphenol P type epoxy resin, bisphenol Z type epoxy resin and other bisphenol type epoxy resin, bisphenol A novolak type epoxy resin, phenol novolac type epoxy resin, cresol novolac epoxy resin and other novolak type epoxy resin, biphenyl type epoxy resin, biphenyl aralkyl Type epoxy resin, arylalkylene type epoxy resin, tetraphenylol ethane type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornen type epoxy resin, adamantan type epoxy resin, Fluorene type epoxy resin, glycidyl methacrylate copolymerized epoxy resin, cyclohexyl maleimide and glycidyl methacrylate copolymerized epoxy resin, epoxy modified polybutadiene rubber derivative, CTBN modified epoxy resin, trimethylpropane polyglycidyl ether, phenyl-1, 3-Diglycidyl ether, biphenyl-4,4'-diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol or propylene glycol diglycidyl ether, sorbitol polyglycidyl ether, tris (2,3-epoxypropyl) ) Isocyanurate, triglycidyltris (2-hydroxyethyl) isocyanurate, phenol novolac resin, cresol novolak resin, novolak type phenol resin such as bisphenol A novolak resin, unmodified resolephenol resin, tung oil, flaxseed oil, walnut oil, etc. Epoxy resin such as resol type phenol resin modified with oil modified with, phenoxy resin, urea (ureia) resin, triazine ring-containing resin such as melamine resin, unsaturated polyester resin, bismaleimide resin, diallyl phthalate resin, Silicone resin, resin with benzoxazine ring, norbornene resin, cyanate resin, isocyanate resin, urethane resin, benzocyclobutene resin, maleimide resin, bismaleimide triazine resin, polyazomethine resin, thermosetting epoxy Examples include reimide.
These thermosetting resins may be used alone or in a blend of two or more. The blending ratio at the time of blending may be appropriately selected according to various uses.

<Photocurable resin>
Specific examples of the photocurable resin include, but are not limited to, known and general (meth) acrylate resins, vinyl resins, epoxy resins and the like. These are roughly classified into a radical reaction type in which a monomer reacts with a radical generated by light and a cationic reaction type in which a monomer is cationically polymerized, depending on the reaction mechanism. Examples of the radical reaction type monomer include (meth) acrylate compounds and vinyl compounds (for example, some vinyl ethers). Epoxy compounds, certain vinyl ethers, and the like correspond to the cationic reaction type. For example, the epoxy compound that can be used as a cationic reaction type can be a monomer of both a thermosetting resin and a photocurable resin.

The (meth) acrylate compound refers to a compound having one or more (meth) acrylate groups in the molecule. Specific examples of the (meth) acrylate compound include monofunctional (meth) acrylate, polyfunctional (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate and the like.

Examples of the vinyl compound include vinyl ether, styrene and styrene derivatives, vinyl compounds and the like. Examples of the vinyl ether include ethyl vinyl ether, propyl vinyl ether, hydroxyethyl vinyl ether, ethylene glycol divinyl ether and the like. Examples of the styrene derivative include methylstyrene and ethylstyrene. Examples of the vinyl compound include triallyl isocyanurate and trimetaallyl isocyanurate.

Further, a so-called reactive oligomer may be used as a raw material for the photocurable resin. As the reactive oligomer, an oligomer having an arbitrary combination selected from a (meth) acrylate group, an epoxy group, a urethane bond, and an ester bond in the same molecule, for example, a (meth) acrylate group and a urethane bond in the same molecule. Urethane acrylate having both (meth) acrylate group and ester bond in the same molecule, epoxy acrylate derived from epoxy resin and having epoxy group and (meth) acrylate group in the same molecule, etc. Be done.

The photocurable resin may be used alone or in a blend of two or more. The blending ratio at the time of blending may be appropriately selected according to various uses.

<Elastomer (rubber)>
Specific examples of the elastomer (that is, rubber) are not particularly limited, but for example, natural rubber (NR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), and isoprene rubber (IR). , Butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), acrylonitrile-styrene-butadiene copolymer rubber, chloroprene rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene co-weight Combined rubber, chlorosulfonated polyethylene rubber, modified natural rubber (epoxidized natural rubber (ENR), hydrogenated natural rubber, deproteinized natural rubber, etc.), ethylene-propylene copolymer rubber, acrylic rubber, epichlorohydrin rubber, polysulfide Examples thereof include rubber, silicone rubber, fluororubber, and urethane rubber. These rubbers may be used alone or in a blend of two or more. The blending ratio at the time of blending may be appropriately selected according to various uses.

The content of the composite particles in the resin composition is preferably 0.5% by mass or more, 1% by mass or more, or 3% by mass or more, or 5 from the viewpoint of obtaining a good effect of improving the physical properties of the fine cellulose fibers. It is preferably 50% by mass or less, 40% by mass or less, or 30% by mass or less, or 20% by mass from the viewpoint of obtaining good dispersibility of the fine cellulose fibers in the resin, which is 50% by mass or more or 10% by mass or more. % Or less.

The mass ratio of the base resin to the total mass of the resin composition is preferably 50% by mass or more, 60% by mass or more, or 70% by mass or more, or 80% by mass or more from the viewpoint of good dispersion of the fine cellulose fibers. From the viewpoint of imparting functions such as high elasticity and reduction of thermal expansion rate to the resin composition by the fine cellulose fibers, it is preferably 99.5% by mass or less, or 90% by mass or less. ..

The amount of the fine cellulose fibers in the resin composition with respect to 100 parts by mass of the resin is preferably 0.1 part by mass or more, 1 part by mass or more, or 2 from the viewpoint of obtaining a good effect of improving the physical properties of the resin composition. It is 4 parts by mass or more, or 3 parts by mass or more, and preferably 40 parts by mass or less, 30 parts by mass or less, or 20 parts by mass or less, or 10 from the viewpoint of fluidity during production and use of the resin composition. It is less than a part by mass. In one aspect, since the dried composite particles are highly redispersed after being mixed with the base resin, sufficient mechanical properties can be realized even if the amount of fine cellulose fibers as compared with the resin is small. Specifically, the ratio of the fine cellulose fibers can be preferably 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the base resin. In particular, since excellent mechanical properties can be realized even if the amount is 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the base resin, problems such as coloration and odor as well as hygroscopicity of the composition are minimized. can do.

The coefficient of linear thermal expansion (CTE) of the resin composition is preferably 80 ppm / k or less, more preferably 70 ppm / k or less, still more preferably 60 ppm / k or less, still more preferably 55 ppm / k or less, and most preferably 50 ppm / k. It is as follows. The smaller the coefficient of linear thermal expansion is, the more preferable it is, but from the viewpoint of ease of production of the resin composition, for example, it may be 5 ppm / K or more, or 10 ppm / K or more.

The storage elastic modulus of the resin composition of the present embodiment is evaluated as the rate of increase of the value with respect to the resin containing no filler component (that is, fine cellulose fibers and other fillers). The rate of increase is preferably 1.3 or more, more preferably 1.4 or more, still more preferably 1.5 or more, even more preferably 1.6 or more, and most preferably 1.7 or more. The rate of increase in the storage elastic modulus of the resin composition of the present embodiment is preferably 1.3 or more, more preferably 1.4 or more, still more preferably 1.5 or more, and most preferably 1.6 or more. ..

Further, in general, the storage elastic modulus of the resin composition becomes remarkably small at a high temperature above the glass transition point, so that the use at a high temperature is restricted. On the other hand, since the resin composition containing composite particles has a small decrease in storage elastic modulus even at a high temperature, it can be used at a high temperature and can be said to have excellent high temperature rigidity. Therefore, the change in storage elastic modulus (also referred to as storage elastic modulus change) between low temperature and high temperature shown in the following formula of the resin composition of the present embodiment is preferably 10 or less, 8 or less, or 6 or less, or 5 Below, or below 4, or below 3. The smaller the change in storage elastic modulus is, the more preferable it is, but from the viewpoint of ease of production of the resin composition, for example, it may be 1 or more, or 2 or more.
Change in storage elastic modulus = low-temperature storage elastic modulus / high-temperature storage elastic modulus The temperature in the low-temperature region and the temperature in the high-temperature region to be measured are set to 50 ° C. and 100 ° C. above the glass transition point of the base resin, respectively. For example, for PA6, the low temperature / high temperature temperature is 0 ° C./150 ° C., and for PP, it is −50 ° C./100 ° C.

<Additional ingredients>
The resin composition of the present embodiment may further contain additional components, if necessary, in order to improve its performance. As the additional component, the same as described above can be exemplified as the additional component in the composite particle.

In a preferred embodiment, an additional dispersant having a function of stably dispersing the fine cellulose fibers in the resin composition may be used. The additional dispersant can improve the mechanical properties of the resin composition by improving and controlling the dispersed state of the fine cellulose fibers in the resin composition. The additional dispersant is selected from the group consisting of the above-mentioned surfactant as an additional component in the composite particle, an organic compound having a boiling point of 160 ° C. or higher, and a resin having a chemical structure capable of highly dispersing fine cellulose fibers. It can be one kind.

The lower limit of the mass ratio of the additional dispersant to the total mass of the resin composition is preferably 0.01% by mass or more, or from the viewpoint of obtaining a good effect of improving the mechanical properties and thermal stability of the resin composition. From the viewpoint that 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and the upper limit is good for maintaining the desired properties of the resin in the resin composition. Therefore, it is preferably 20% by mass or less, 10% by mass or less, or 5% by mass or less, or 3% by mass or less.

The resin composition can be prepared by mixing the composite particles and the resin. Further, a molded product can be produced by molding the resin composition. When the composite particles and the resin are mixed, both components may be mixed at room temperature without heating and then heated, or may be mixed while heating. When heating, the mixing temperature can be adjusted according to the resin used.

When the resin is a thermoplastic resin, the minimum processing temperature recommended by the thermoplastic resin supplier is 255 to 270 ° C. for nylon 66 (also referred to as polyamide "PA66") and nylon 6 (also referred to as polyamide "PA6"). The temperature is 225 to 240 ° C., the temperature is 170 ° C. to 190 ° C. for a thermoplastic resin (also referred to as POM), and 160 to 180 ° C. for polypropylene (also referred to as PP). The heating set temperature is preferably in the temperature range of 20 ° C. higher than these recommended minimum processing temperatures. By setting the mixing temperature within this temperature range, the fine cellulose fibers and the resin can be uniformly mixed.

When the base resin is a thermoplastic resin, the method for producing the resin composition is not particularly limited, but for example,
1. 1. After melt-kneading the mixture of composite particles and thermoplastic resin using a single-screw or twin-screw extruder,
(1) A method of extruding into a strand shape and cooling and solidifying in a water bath to obtain a pellet-shaped molded product of a resin composition.
(2) A method of extruding and cooling in a rod shape or a tubular shape to obtain an extruded molded product of a resin composition, or (3) a method of extruding from a T die to obtain a sheet-shaped or film-shaped molded product of a resin composition, or 2 .. The composite particles and the thermoplastic resin monomer are mixed and a polymerization reaction (specifically, solid phase polymerization, emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, etc.) is carried out, and the obtained product is obtained from the above (1). )-(3), a method for obtaining a molded product of the resin composition.

An extruder such as a single-screw extruder or a twin-screw extruder can be used for melt-kneading, but the twin-screw extruder is preferable in controlling the dispersibility of cellulose. The L / D obtained by dividing the cylinder length (L) of the extruder by the screw diameter (D) is preferably 40 or more, and particularly preferably 50 or more. The screw rotation speed during kneading is preferably in the range of 100 to 800 rpm, more preferably in the range of 150 to 600 rpm. These vary depending on the screw design.

Each screw in the cylinder of the extruder is optimized by combining an elliptical two-blade screw-shaped full flight screw, a kneading element called a kneading disc, and the like.

In one aspect, an addition port is provided in the middle of the cylinder of the extruder, and the raw material charged into the addition port is guided to a screw in the cylinder. In one aspect, the location of the addition port is located downstream of the melt-kneading zone. In normal kneading using an extruder, the first resin melting zone is the region where shearing is most strongly applied. Therefore, by adding a filler component to the unmelted resin moving in the transport zone, it is subsequently heated and melted. The shearing force below finely disperses the filler. However, when cellulose is finely dispersed in the resin as a reinforcing filler, if cellulose is added before the resin melting zone, the cellulose may deteriorate due to a strong shearing force in the resin melting zone. In particular, when fine cellulose fibers having a diameter of nanometer size (that is, less than 1000 nm) of cellulose alone are used, the surface area thereof is extremely large, so the ratio of the amount of the usual filler component added to the resin (specifically, the filler). When an attempt is made to design a reinforced resin composition with a filler component of 20% by mass or more based on a total of 100% by mass of the component and the resin), the deterioration of the fine cellulose fiber due to the shearing force becomes large, and the original property of the fine cellulose fiber is increased. Problems such as loss of strong crystal structure, deterioration of mechanical properties as a reinforcing resin, coloring and odor may occur.

Since the composite particles of the present disclosure can have excellent redispersibility even in a dry state, fine dispersion is possible without exposing the composite particles to the shearing. That is, composite particles can be added to the molten thermoplastic resin. The composite particles are rapidly finely dispersed in the resin that is already in a molten state, and even if the amount of the composite particles added is extremely small, for example, 10 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin that is the base resin, it is good as a reinforcing filler. It is possible to exhibit various functions, surely improve the mechanical properties of the finally obtained resin composition, and satisfactorily suppress problems such as coloring and odor.

For the purpose of reducing the heat history received when passing through the inside of the cylinder, it is preferable to design the addition port on the downstream side of the melt-kneading zone of the extruder. Specifically, it is preferable to design the length (L2) from the outlet of the cylinder to the addition port to 1/2 or less of the total length (L1) of the cylinder. The total length of the cylinder includes a portion not involved in kneading (for example, a transport zone).

Composite particles are charged from the addition port and mixed into the thermoplastic resin melt-kneaded in the extruder. Since the composite particles of the present embodiment have excellent redispersibility, they can be highly dispersed in the resin even if they are charged in a later step in the extruder.

When the thermoplastic resin is an engineering plastic having excellent heat resistance, its melting temperature is extremely high, so that a strong heat history is applied to the fine cellulose fibers during processing, and problems of coloring and odor due to burning are likely to occur. .. In addition, since this strong thermal history partially loses the excellent mechanical properties of cellulose (particularly natural cellulose), the mechanical properties of the resin composition are improved when cellulose is added as a filler to the thermoplastic resin. Reduces the effect.

In the present embodiment, since the fine cellulose fibers are previously modified into composite particles having excellent redispersibility even in a dry state by using an amide compound, the fine cellulose fibers are modified with respect to the molten resin (preferably). Is an addition located downstream of the melt-kneading zone of the extruder, more preferably L2 / L1 of 1/2 or less, still more preferably L2 / L1 of 1/3 or less, and most preferably L2 / L1 of 1/4 or less. Adding composite particles to the cylinder (by mouth) can also produce a highly dispersed resin composition of fine cellulose fibers. In the fine cellulose fibers charged in the above-described manner, the heat history is relaxed, so that coloring and generation of odor due to burning are suppressed. Further, according to the method of the present embodiment, it is possible to realize a high degree of dispersion of fine cellulose fibers as well as a relaxation of the heat history, so that a high degree of mechanical properties of the resin composition can be realized.

A degassing cylinder, a vacuum vent, etc. may be appropriately provided downstream of the extruder including the addition port (side feeder) to degas the air and a small amount of water (steam) mixed in when the composite particles are charged. can.

Further, in the twin-screw extruder, a high pressure is applied to the resin at the tip discharge portion, and the resin temperature tends to rise. A gear pump can be installed downstream for the purpose of controlling the resin pressure and reducing the resin temperature rise.

In the present embodiment, the distance that the composite particles are conveyed in the extruder can be shortened as compared with the thermoplastic resin. Therefore, by devising the structure of the screw in the cylinder after the composite particles are mixed, reliable homogeneous dispersion is realized. can do. Specifically, but not limited to this, fine cellulose fibers are provided by providing one or more counterclockwise screws that create a feed in the direction opposite to the traveling direction in the cylinder downstream of the addition port. A high degree of dispersion can be achieved more reliably.

The water content of the resin composition is not particularly limited, but in the case of polyamide, for example, it is preferably 10 ppm or more in order to suppress an increase in the molecular weight of the polyamide during melting, and 1200 ppm in order to suppress hydrolysis of the polyamide during melting. It is preferably less than or equal to, more preferably 900 ppm or less, and most preferably 700 ppm or less. Moisture content is a value measured using a Karl Fischer titer in a manner compliant with ISO 15512.

Resin compositions using a thermoplastic resin as a base resin can be provided in various shapes. Specific examples thereof include resin pellets, sheets, fibers, plates, rods and the like. Above all, the resin pellet shape is more preferable from the viewpoint of ease of post-processing and ease of transportation. Preferred pellet shapes at this time include a round shape, an elliptical shape, a cylindrical shape, and the like, which differ depending on the cutting method at the time of extrusion processing. Pellets cut by a cutting method called underwater cut often have a round shape, and pellets cut by a cutting method called hot cut often have a round or oval shape, which is called a strand cut. Pellets cut by the method often have a columnar shape. In the case of a round pellet, the preferred size is 1 mm or more and 3 mm or less as the pellet diameter. Further, in the case of columnar pellets, the preferable diameter is 1 mm or more and 3 mm or less, and the preferable length is 2 mm or more and 10 mm or less. The above diameter and length are preferably not more than the lower limit from the viewpoint of operational stability during extrusion, and preferably not more than the upper limit from the viewpoint of biting into the molding machine in post-processing.

The resin composition using the thermoplastic resin as the base resin can be molded into resin molded bodies having various shapes (for example, film-like, sheet-like, fibrous, plate-like, pellet-like, powder-like, three-dimensional structure, etc.). The manufacturing method of the resin molded product is not particularly limited, but injection molding (for example, injection compression molding, injection press molding, gas assisted injection molding, and ultra-high speed injection molding), various extrusion molding (cold runner method or hot runner method), Examples include foam molding (including injection of supercritical fluid), insert molding, in-mold coating molding, heat insulating mold molding, rapid heating and cooling mold molding, and various deformed extrusion molding (for example, two-color molding and sandwich molding). can. For example, various extrusion moldings are suitable for molding sheets, films, fibers and the like. Inflation method, calendar method, casting method and the like can also be used for forming the sheet or film. Further, it can be molded as a heat-shrinkable tube by applying a specific stretching operation. It is also possible to make a hollow molded product by rotary molding, blow molding or the like. Of these, the injection molding method is particularly preferable from the viewpoint of design and cost.

The method for producing the resin composition in which the base resin is a thermosetting resin or a photocurable resin is not particularly limited, but for example, the composite particles are sufficiently dispersed in the base resin solution or the base resin powder dispersion and dried. Method, method in which composite particles are sufficiently dispersed in a base resin monomer solution and polymerized by heat, UV irradiation, polymerization initiator, etc., base on a molded body composed of composite particles (for example, sheet, powder particle molded body, etc.) A method of sufficiently impregnating a resin solution or a base resin powder dispersion and drying, a method of sufficiently impregnating a molded body composed of composite particles with a base resin monomer solution and polymerizing with heat, UV irradiation, a polymerization initiator, etc. Can be mentioned. At the time of curing, various polymerization initiators, curing agents, curing accelerators, polymerization inhibitors and the like can be blended.

A resin composition based on a thermosetting resin or a photocurable resin can be used as various resin molded products. There is no particular limitation on the method for producing the resin molded product.

In the case of a thermosetting resin, an extrusion molding method is generally used to produce a plate-shaped product, but a flat press can also be used. In addition, a deformed extrusion molding method, a blow molding method, a compression molding method, a vacuum forming method, an injection molding method and the like can be used. In addition to the melt extrusion method, a solution cast method can be used to manufacture film-like products. When the melt molding method is used, inflation film molding, cast molding, extrusion lamination molding, calendar molding, and sheet molding can be used. , Fiber molding, blow molding, injection molding, rotary molding, coating molding and the like.

Further, a method may be used in which a sheet called an uncured or semi-cured prepreg is prepared, and then the prepreg is made into a single layer or a laminated layer and pressed and heated to cure and mold the resin. Examples of the method of applying heat and pressure include, but are not limited to, a press molding method, an autoclave molding method, a bagging molding method, a lapping tape method, and an internal pressure molding method.

Further, a method of impregnating a filament or preform of a reinforcing fiber such as carbon fiber with a resin composition before curing the base resin and then curing the base resin to obtain a molded product (for example, RTM, VaRTM, filament winding, etc.). (Forming method such as RFI) can be mentioned, but the present invention is not limited to these molding methods.

When the base resin is a photocurable resin, a molded product can be manufactured by using various curing methods using active energy rays.

The method for producing the resin composition when the base resin is rubber is not particularly limited. For example, a method of kneading the composite particles and rubber in a dry manner, or a method of dispersing or dissolving the composite particles and rubber in a dispersion medium. After that, a method of drying and kneading can be mentioned. As the mixing method, a homogenizer mixing method is preferable in that high shearing force and pressure can be applied to promote dispersion, but in addition, a propeller type stirring device, a rotary stirring device, an electromagnetic stirring device, manual stirring, etc. The method can also be used. The obtained resin composition is molded into a desired shape and can be used as a molding material. Examples of the shape of the molding material include sheets, pellets, powders and the like.

Resin compositions using rubber as a base resin can be used as various resin molded products. The method for producing the resin molded product is not particularly limited, and the molding material is molded by a desired molding method such as mold molding, injection molding, extrusion molding, hollow molding, foam molding, etc., and the desired shape is not added. A molded product of sulfur can be obtained. The unvulcanized molded product can be vulcanized by heat treatment or the like, if necessary.

≪Use≫
Since the resin composition containing the composite particles of the present embodiment can have high heat resistance and light weight, a steel plate, a fiber reinforced plastic (for example, carbon fiber reinforced plastic, a glass fiber reinforced plastic, etc.), a resin composite containing an inorganic filler, It is useful as a substitute for such as. Suitable applications for resin compositions include industrial machinery parts, general machinery parts, automobiles / railways / vehicles / ships / aerospace-related parts, electronic / electrical parts, construction / civil engineering materials, daily necessities, sports / leisure goods, etc. Examples thereof include housing members for wind power generation, containers / packaging members, and the like.

Hereinafter, the present invention will be further described based on examples, but the present invention is not limited to these examples.

≪Fine cellulose fiber≫
Those prepared in Production Examples 1 and 2 below were used.

[Production Example 1] (Production of fine cellulose fiber CNF-A)
3 parts by mass of cotton linter pulp was immersed in 27 parts by mass of water and heat-treated in an autoclave at 130 ° C. for 4 hours. The obtained swollen pulp was washed with water to obtain purified pulp (30 parts by mass) containing water. Subsequently, 170 parts by mass of water was added to 30 parts by mass of purified pulp containing water and dispersed in water (solid content ratio: 1.5% by mass), and as a disc refiner device, SDR14 type laboratory refiner manufactured by Aikawa Iron Works Co., Ltd. ( Using a pressurized DISK type), the aqueous dispersion was beaten for 30 minutes with a clearance between discs of 1 mm. Subsequently, beating was carried out thoroughly under the condition that the clearance was reduced to a level close to almost zero, and a beating aqueous dispersion (solid content concentration: 1.5% by mass) was obtained. The obtained beating water dispersion was subjected to a micronization treatment 10 times under an operating pressure of 100 MPa using a high-pressure homogenizer (NSO15H manufactured by Niro Soabi (Italy)) as it was, and a fine cellulose fiber slurry (solid content concentration: 1.5). Mass%) was obtained. Then, it was concentrated to a solid content of 10% by mass by a dehydrator to obtain 30 parts by mass of a concentrated slurry A of fine cellulose fibers.

[Production Example 2] (Production of fine cellulose fiber CNF-B)
10 parts by mass of the concentrated slurry A (solid content ratio 10% by mass) of Production Example 1 was added to 80 parts by mass of DMSO, dispersed with a homogenizer, and then treated with a centrifuge at 9000 rpm for 15 minutes to remove the supernatant. 30 parts by mass of DMSO slurry was obtained. Subsequently, 60 parts by mass of DMSO was added, and DMSO replacement treatment for performing the same dispersion and centrifugation was carried out three times, and 30 parts by mass of DMSO slurry (solid content ratio 3.3% by mass, water content <1% by mass) was carried out. Got
30 parts by mass of the DMSO slurry obtained in Production Example 2 was placed in a separable flask, 15 parts by mass of DMSO was added, and the mixture was heated to 70 ° C. while being uniformly stirred with a stirring blade. Subsequently, 2 parts by mass of vinyl acetate and 0.3 parts by mass of sodium hydrogen carbonate were added, and the mixture was stirred at 70 ° C. for 3 hours. To stop the reaction, 100 parts by mass of water was added with stirring. Subsequently, the solid content was filtered off by filtration. After adding 500 parts by mass of water to the obtained solid content and dispersing it with a mixer, a washing operation of filtering was carried out four times, and a concentrated slurry B of acetylated fine cellulose fibers (solid content ratio 10% by mass) was carried out. ) Was obtained.

<Evaluation of fine cellulose fibers>
[Measurement sample preparation]
First, the concentrated slurry was added to tert-butanol, and further dispersed with a mixer or the like until there were no agglutinates. The concentration was adjusted to 0.5% by mass with respect to the weight of the fine cellulose fiber solid content of 0.5 g. 100 g of the obtained tert-butanol dispersion was filtered on a filter paper, dried at 150 ° C., and then the filter paper was peeled off to obtain a sheet. A porous sheet having an air permeation resistance of 100 sec / 100 ml or less per ^{10 g / m 2 of the sheet was used as a measurement sample.
After measuring the basis weight W (g / m 2} ) of the sample left to stand in an environment of 23 ° C. and 50% RH for 1 day, a Wangken type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01) was used. The air permeation resistance R (sec / 100 ml) was measured. ^{At this time, the value per 10 g / m 2} basis weight was calculated according to the following formula.
Air permeation resistance per 10 g / m ² basis weight (sec / 100 ml) = R / W x 10

[Number average fiber diameter]
The concentrated slurry was diluted with tert-butanol to 0.01% by mass, and dispersed using a high-shear homogenizer (manufactured by IKA, trade name "Ultratalax T18") under treatment conditions: rotation speed of 25,000 rpm x 5 minutes. It was cast on mica and air-dried, and measured with a high-resolution scanning electron microscope. The measurement was performed by adjusting the magnification so that at least 100 cellulose fibers were observed, the major axis (L) of 100 randomly selected cellulose fibers was measured, and the summed average of 100 cellulose fibers was calculated. Calculated.

[Crystallinity]
X-ray diffraction measurement of the porous sheet was performed, and the crystallinity was calculated from the following formula.
Crystallinity (%) = [I ₍₂₀₀₎ −I _(amorphous) ] / I ₍₂₀₀₎ × 100
I _{(200) : Diffraction peak intensity due to amorphous in the} cellulose type I crystal by 200 planes (2θ = 22.5 °) I (amorphous): Hello peak intensity due to amorphous in the cellulose type I crystal, 4 from the diffraction angle of 200 planes Peak intensity on the low angle side (2θ = 18.0 °) of .5 °

(X-ray diffraction measurement conditions)
Equipment MiniFlex (manufactured by Rigaku Co., Ltd.)
Operation axis 2θ / θ
Radioactive source CuKα
Measurement method Continuous voltage 40kV
Current 15mA
Start angle 2θ = 5 °
End angle 2θ = 30 °
Sampling width 0.020 °
Scan speed 2.0 ° / min
Sample: Paste a porous sheet on the sample holder

[DS]
The infrared spectroscopic spectra of the porous sheet at five locations by the ATR-IR method were measured with a Fourier transform infrared spectrophotometer (FT / IR-6200 manufactured by JASCO). Infrared spectroscopic spectrum measurement was performed under the following conditions.
Accumulation number: 64 times,
Wavenumber resolution: 4 cm ^-1 ,
Wavenumber range: 4000-600cm ^-1 ,
ATR crystal: diamond,
Incident angle: 45 °
From the obtained IR spectrum, the IR index was calculated by the following equation (1):
IR index = H1730 / H1030 ... (1)
Calculated according to. In the formula, H1730 and H1030 are the absorbances at 1730 cm ^-1 and 1030 cm ^-1 (absorption band of cellulose skeleton chain CO stretching vibration). However, each of the line connecting the lines and 800 cm ^-1 and 1500 cm ^-1 connecting 1900 cm ^-1 and 1500 cm ^-1 as a baseline, means absorbance when the baseline was zero absorbance.
Then, the average degree of substitution at each measurement location was calculated from the IR index according to the following equation (2), and the average value was taken as DS.
DS = 4.13 x IR index ... (2)

[Weight average molecular weight (Mw), number average molecular weight (Mn)]
0.88 g of the porous sheet was weighed, chopped into small pieces with scissors, stirred lightly, 20 mL of pure water was added, and the mixture was left to stand for 1 day. The water and solids were then separated by centrifugation. Subsequently, 20 mL of acetone was added, and the mixture was lightly stirred and left to stand for 1 day. Acetone and solids were then separated by centrifugation. Subsequently, 20 mL of N, N-dimethylacetamide was added, and the mixture was lightly stirred and left to stand for 1 day. After separating N, N-dimethylacetamide and solid content by centrifugation again, 20 mL of N, N-dimethylacetamide was added, and the mixture was lightly stirred and left to stand for 1 day. The N, N-dimethylacetamide and the solid content were separated by centrifugation, 19.2 g of the N, N-dimethylacetamide solution prepared so that lithium chloride was 8% by mass was added to the solid content, and the mixture was stirred with a stirrer. It was confirmed that it was visually dissolved. The solution in which cellulose was dissolved was filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The equipment and measurement conditions used are as follows.
Equipment: Tosoh HLC-8120
Column: TSKgel SuperAWM-H (6.0 mm ID x 15 cm) x 2 Detector: RI detector Eluent: N, N-dimethylacetamide (lithium chloride 0.2%)
Flow velocity: 0.6 mL / min Calibration curve: Pullulan conversion

[Average content of acid-insoluble components]
The quantification of the acid-insoluble component was carried out by the Clarson method described in the non-patent document (Wood Science Experiment Manual, edited by Japan Wood Society, pp. 92-97, 2000) for the fine cellulose fiber raw material. Weigh the raw material of the absolutely dried fine cellulose fiber, put it in a predetermined container, add 72% by mass concentrated sulfuric acid, press it appropriately with a glass rod so that the contents are uniform, and then autoclave to cellulose and hemicellulose. Was dissolved in an acid solution. After allowing to cool, the contents were filtered through a glass fiber filter paper to obtain an acid-insoluble component as a residue. The acid-insoluble component content was calculated from the weight of the acid-insoluble component, and the number average of the acid-insoluble component contents calculated for the three samples was taken as the acid-insoluble component average content.

[Average content of alkali-soluble polysaccharides]
The alkali-soluble polysaccharide content is based on the method described in the non-patent literature (Wood Science Experiment Manual, edited by Japan Wood Society, pp. 92-97, 2000) for the raw material of fine cellulose fiber, and the holocellulose content (Wise method). It was obtained by subtracting the α-cellulose content from. The alkali-soluble polysaccharide content was calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide content was taken as the average alkali-soluble polysaccharide content of the fine cellulose fibers.

<< Amide compounds and non-amide compounds >>
The following four compounds and those prepared in Production Examples 3 and 4 were used.
ε-Caprolactam (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 113)
2-Pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 85)
(6-Aminohexaneamide) Caproic acid (manufactured by Advanced ChemBlocks Inc., also referred to as AHAHA, molecular weight 244)

[Production Example 3] (Production of water-soluble polyamide)
10 parts by mass of adipic acid, 15 parts by mass of trioxatridecanediamine and 16.6 parts by mass of water were introduced into a reactor inactivated with nitrogen and heated to 245 ° C. As soon as this temperature was reached, decompression began. After reaching this temperature, the reactor was depressurized to normal pressure over 1 hour. The polymer melt was then maintained at 245 ° C. for an additional hour with stirring and the reaction water was removed at normal pressure by passing nitrogen through. After pressurizing with 5 bar of nitrogen, the contents of the reactor were drained through a die plate. After cooling the polymer strands of the fluidized bed, they were granulated to produce a water-soluble polyamide. The water-soluble polyamide had a relative solution viscosity of 9000 and 1.93 with a number average molecular weight, a COOH terminal group concentration of 31 mmol / kg and an NH ₂ terminal group concentration of 38 mmol / kg.

[Manufacturing Example 4] (Manufacturing of polyamide powder)
Polyamide 6 (manufactured by Ube Industries, Ltd., product number 1013B, also referred to as PA6) was freeze-pulverized to produce polyamide powder (also referred to as PA6 powder) (number average molecular weight: 13000).

The following five compounds were used as the non-amide compounds.
ε-Caprolactone (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 114)
6-Aminocaproic acid (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 131)
Polyethylene glycol (manufactured by Sigma-Aldrich, molecular weight 4000)
Carboxymethyl cellulose (manufactured by Daicel, product number 1140)
Oleic acid (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 282)

≪Evaluation of amide compounds and non-amide compounds≫
[Melting point]
The peak top of the melting peak was read with a differential scanning calorimeter (DSC, DSC8000 manufactured by PERKIN ELMER) and used as the melting point. The measurement was carried out at a heating rate of 10 ° C./min from −10 ° C. to a temperature at which the amide compound and the non-amide compound were completely melted.

[solubility]
Regarding the solubility of the amide compound, 1 g of the amide compound was added to 99 g of ion-exchanged water, the mixture was stirred for 1 hour while heating at 90 ° C., and cooled to 25 ° C. The obtained 1% by mass aqueous solution was visually inspected, and if there was no insoluble matter, it was good, and if it was, it was bad.

[Hygroscopicity]
The hygroscopicity of the amide compound was evaluated from the equilibrium water content in an environment of 23 ° C. and 60% RH. Specifically, a 1% by mass solution is prepared by dissolving the amide compound in a solvent, 0.5 g of glass fiber is added to 10 g of the 1% by mass solution, dried in an oven, and then completely dried under vacuum conditions (120 ° C.). After 2 hours), the humidity was adjusted at 23 ° C. and 60% RH, and the equilibrium water content (%) was determined. The moisture absorption of the glass fiber is 0, and the weight increase is due to the moisture absorption by the dispersant. As for hygroscopicity, an equilibrium moisture content of 20% or more was good, 10% or more and less than 20% was acceptable, and less than 10% was poor.

[Molecular weight]
The molecular weights of amide compounds and non-amide compounds are calculated by calculation from chemical formulas for structurally defined low molecular weight compounds, and after dissolving water-soluble polyamide, polyethylene glycol, and carboxymethyl cellulose in water, gel permeation using water as a solvent. It was determined by chromatography in terms of purulan. Specifically, a 0.1% by mass aqueous solution was prepared, filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The equipment and measurement conditions used are as follows.
Equipment: Tosoh HLC-8120
Column: TSKgel α-M (7.8 mm ID x 30 cm) x 2 Detector: RI detector Eluent: 0.1 M NaCl aqueous solution Flow rate: 1.0 mL / min Calibration curve: Pullulan conversion

≪Composite particles or comparative particles≫
[Example 1]
ε-Caprolactam was dissolved in water to produce a 10% by mass aqueous solution of ε-caprolactam. To 1000 parts by mass of the concentrated slurry A obtained in Production Example 1 (100 parts by mass of CNF-A), 1000 parts by mass of an aqueous solution of 10% by mass of ε-caprolactam was added (100% by mass with respect to the fine cellulose fibers), and the planetary was added. After stirring in a mixer (Primix Corporation, trade name "Hibismix 2P-1") at 50 rpm for 10 minutes at 25 ° C. and atmospheric pressure, the jacket temperature is 80 ° C., a reduced pressure condition of -0.1 MPa, and 8 at 50 rpm. Time vacuum drying treatment was performed. The obtained dried product was pulverized with a tabletop pulverizer (Mini Speed Mill MS-05 manufactured by Labonect Co., Ltd.) to obtain composite particles P1.

[Examples 2 to 8 and Comparative Examples 1 to 3]
After producing a 10% by mass aqueous solution of the amide compound, composite particles P2 to P13 were obtained in the same manner as in Example 1 with the compositions shown in Table 2. In Comparative Example 2, since a 10% by mass aqueous solution could not be produced, ε-caprolactone was directly added to obtain P14. For Comparative Example 3, no amide compound was added to obtain P15.

[Examples 9 to 12, Comparative Examples 4 to 9]
Composite particles P9 to 12, 16 and 17 were obtained in the same manner as in Example 1 with the compositions shown in Table 2 except that concentrated slurry B (CNF-B) was used instead of concentrated slurry A. As for Comparative Examples 6 and 7, since a 10% by mass aqueous solution could not be produced, oleic acid and PA powder were directly added to obtain P18 and P19. For Comparative Examples 8 and 9, no amide compound was added to obtain P20 and 21.

<Evaluation of composite particles or comparative particles>
[Viscosity difference Δη _30-100 , thixotropy index (TI), Δη _max ]
A predetermined amount of particles were added to water so that the amount of the fine cellulose fibers was 0.5% by mass, and 100 ml of an aqueous dispersion containing the particles was prepared. Subsequently, using a high-shear homogenizer (manufactured by IKA, trade name "Ultratalax T18"), the mixture was dispersed at a treatment condition: rotation speed of 25,000 rpm x 5 minutes. After confirming that the liquid temperature was 25 ° C., a part of the dispersion liquid being stirred was taken, and the viscosity was immediately measured with a rheometer (TA Instrument Co., Ltd., product name: ARES) using a double cylindrical geometry. .. The temperature of the device was adjusted to 25 ° C. in advance.
As a measurement condition, a cycle of decreasing the shear rate from 100 seconds- ¹ to 1 second- ¹ over 100 seconds and then increasing it from 100 seconds- ¹ over 100 seconds was repeated twice. Finally, the ^{viscosity was lowered from 100 seconds-1} to 1 second- ¹ over 100 seconds, and viscosity data was acquired every second. Then, the viscosities at shear rates of 30 seconds- ¹ and 100 seconds- ¹ o'clock were set to η ₃₀ and η ₁₀₀ , respectively.
_{The viscosity difference Δη 30-100} was calculated according to the following formula.
Δη _30-100 = η ₃₀ −η ₁₀₀
The thixotropy index TI was calculated according to the following formula.
TI = η ₃₀ / η ₁₀₀
Further, in the third cycle, the _{maximum viscosity difference (Δη max} ) is the viscosity difference at the point where the viscosity difference at the same shear rate when the shear rate is increased and decreased is the maximum in the region where ^{the shear rate is 30 seconds-1 or less.} And said.

≪Resin composition≫
9 parts by mass of the obtained composite particle or comparative particle and the following thermoplastic resin using a twin-screw extruder (OMEGA30H manufactured by STEER, L / D = 60) having 13 cylinder blocks. The fine cellulose fibers were melt-kneaded under the following conditions so that the weight of the fine cellulose fibers was 1 part by mass to obtain pellets of the fine cellulose fiber-reinforced thermoplastic resin.

(Thermoplastic resin)
-UBE Nylon 1013B Polyamide 6 manufactured by Ube Industries, Ltd. (hereinafter referred to as PA)
Carboxylic acid terminal group ratio is ([COOH] / [all terminal groups]) = 0.59
-Prime Polypro J105G Prime Polymer Polypropylene (hereinafter referred to as PP)

(Melting and kneading conditions)
Rotation speed: 300 rpm
Cylinder temperature: 250 ° C (for PA) or 200 ° C (for PP)

<Evaluation of resin composition>
[Coefficient of linear expansion (CTE)]
The resin composition or resin was cut into a width of 3 mm and a length of 25 mm to prepare a measurement sample. Using a TMA6100 type device manufactured by SII, in a tension mode, a chuck distance of 10 mm, a load of 5 g, a nitrogen atmosphere, and a temperature of 5 ° C./min from room temperature to 120 ° C. After the temperature was raised in, the temperature was raised to 25 ° C. at 5 ° C./min. The temperature was lowered at 5 ° C./min. From 25 ° C. to 120 ° C. again. The temperature was raised in. At this time, the average coefficient of linear thermal expansion between 0 ° C. and 60 ° C. at the time of the second temperature rise was measured.

[Storage modulus]
The resin composition pellets were melted in an injection molding machine at 260 ° C. for PA6 and 160 ° C. for PP to prepare a dumbbell-shaped test piece of JIS K7127 standard. The apparatus and measurement conditions used for the storage elastic modulus measurement are as follows.
Equipment: GABO Eplexer Measurement mode: Tensile frequency: 10Hz
Temperature range: -130 ° C to 150 ° C
Temperature rise rate: 3 ° C./min Measurement atmosphere: Change in nitrogen storage elastic modulus was calculated according to the following formula.
Change in storage elastic modulus = low temperature storage elastic modulus / high temperature storage elastic modulus PA6 was set to 0 ° C./150 ° C., and PP was set to −50 ° C./100 ° C. Generally, the storage elastic modulus becomes smaller as the temperature becomes higher, so that the storage elastic modulus change is 1 or more. The closer this value is to 1, the smaller the change in storage elastic modulus at high temperature is, and the better the heat resistance (high temperature rigidity) is.

[exterior]
Regarding the appearance of the resin composition sample, compared with the resin composition containing no composite particles (containing only fine cellulose fibers), the one that is clearly brown is defective, and the one that does not show discoloration is good or slightly brown. I made things acceptable. That is, Examples 1 to 8 and Comparative Examples 1 to 2 were compared with Comparative Example 3, Examples 9, 11 and 12, Comparative Examples 4 to 7 were compared with Comparative Example 8, and Example 10 was compared with Comparative Example 9.

Since the composite particles of the present disclosure can satisfactorily disperse fine cellulose fibers in a resin composition and give a resin molded body having extremely excellent mechanical properties, they can be suitably applied to various uses such as metal substitution.

Claims (24)

Composite particles containing fine cellulose fibers and an amide compound.
A composite particle having a viscosity η ₁₀₀ of 20 mPa · s or more at ^{25 ° C. and a shear rate of 100 seconds-1} of a slurry obtained by dispersing the composite particles in water at a fine cellulose fiber concentration of 0.5% by mass. The composite particle according to claim 1, wherein the liquid fraction is 30% by mass or less. Of the slurry, the difference between the viscosity eta ₃₀ in viscosity eta ₁₀₀ and 25 ° C. and a shear rate of 30 sec ^-1 at 25 ° C. and a shear rate of 100 sec ^-1 is 20 mPa · s or more, according to claim 1 or 2 Composite particles. The composite particle according to any one of claims 1 to 3, wherein the slurry exhibits viscosity hysteresis at 25 ° C. and a shear rate of 30 seconds- ^{1 or less.} The composite particle according to any one of claims 1 to 4, wherein the fine cellulose fiber has a fiber diameter of 2 nm or more and less than 1000 nm. The composite particle according to any one of claims 1 to 5, wherein the fine cellulose fiber is a chemically modified fine cellulose fiber. The composite particle according to claim 6, wherein the chemical modification is esterification. The composite particle according to claim 7, wherein the esterification is acetylation. The composite particle according to any one of claims 1 to 8, wherein the fine cellulose fiber has a weight average molecular weight (Mw) of 100,000 or more and a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 6 or less. .. The composite particle according to any one of claims 1 to 9, wherein the average content of the acid-insoluble component of the fine cellulose fiber is 10% by mass or less. The composite particle according to any one of claims 1 to 10, wherein the alkali-soluble polysaccharide content of the fine cellulose fiber is 12% by mass or less. The composite particle according to any one of claims 1 to 11, wherein the amide compound has an amide bond in the molecular skeleton. The composite particle according to any one of claims 1 to 12, wherein 1 g or more of the amide compound is dissolved in 100 g of water at 25 ° C. The composite particle according to any one of claims 1 to 13, wherein the amide compound has a moisture absorption rate of 10% or more at 23 ° C. and 60% RH. The difference ΔYI between the yellowness of the amide compound and the yellowness after heating the amide compound at 190 ° C. in a nitrogen atmosphere for 4 hours is 30 or less, according to any one of claims 1 to 14. The composite particle of the description. The composite particle according to any one of claims 1 to 15, wherein the amide compound has a melting point of 300 ° C. or lower. The composite particle according to any one of claims 1 to 16, wherein the amide compound is a cyclic amide. The composite particle according to any one of claims 1 to 17, wherein the amide compound is caprolactam. The composite particle according to any one of claims 1 to 18, wherein the median particle size of the composite particle is 1 μm to 5000 μm. The method for producing composite particles according to any one of claims 1 to 19.
Preparing a slurry of fine cellulose fibers and
The slurry and the amide compound are mixed and then dried.
Including methods. A resin composition containing the composite particles according to any one of claims 1 to 19 and a resin. A method for producing a resin composition containing fine cellulose fibers, an amide compound, and a resin.
A method comprising mixing the composite particles according to any one of claims 1 to 19 with a resin. A resin pellet formed from the resin composition according to claim 21. A resin molded product formed from the resin composition according to claim 21.

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