Resin composition and method for producing the same

Abstract

To provide a resin composition which achieves a good balance between mechanical characteristics and decorative as well as aesthetic qualities at high levels; and a method for producing the resin composition.SOLUTION: One aspect of the present invention provides: a resin composition which contains cellulose nanofibers, a resin, and a liquid polymer that has a thermal decomposition initiation temperature of more than 200°C; and a method for producing the resin composition. In one aspect, the liquid polymer contains a diene rubber. In one aspect, the liquid polymer is one or more selected from the group consisting of a polybutadiene, a butadiene-styrene copolymer, a polyisoprene, and a polychloroprene.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition containing cellulose nanofibers and a method for producing the same. [Background technology]

[0002] Resin materials are light and have excellent processing properties, and are therefore widely used in many fields, such as automobile parts, electrical and electronic parts, office equipment housings, and precision parts. However, resin alone often has insufficient mechanical properties and dimensional stability, so composites of resin and various fillers are generally used. In recent years, the use of cellulose nanofibers (CNFs), which are natural materials, as such fillers has been considered. CNFs have the advantage of having excellent mechanical properties while being environmentally friendly, but due to their fine structure, they tend to aggregate easily in a dry state, so they are manufactured as a dispersion liquid that allows stable dispersion. For example, when applying cellulose nanofibers to various applications, the above-mentioned dispersion liquid may be directly mixed with a resin, or the dispersion liquid may be dried and then dispersed in a dispersion medium or mixed with a resin in its dried form. However, in cellulose nanofibers, aggregation due to hydrogen bonds between cellulose molecules is extremely strong, so various methods have been proposed to suppress the aggregation of cellulose nanofibers.

[0003] For example, Patent Document 1 describes a dispersion for cellulose nanofibers that can disperse cellulose nanofibers without agglomerating them, the dispersion containing (A) a surface treatment agent that is a water-soluble polymer having hydrophilic and hydrophobic segments and a number average molecular weight of 200 to 30,000, (B) polyurethane, and water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-063408 A Summary of the Invention [Problem to be solved by the invention]

[0005] The properties required of resin compositions containing cellulose nanofibers are becoming more advanced year by year, and in particular, molded articles obtained by molding resin compositions are now required to have not only excellent mechanical properties, but also decorative properties and beautiful appearances due to high surface smoothness. The technology described in Patent Document 1 aims to increase the dispersibility of cellulose nanofibers by using a dispersion liquid containing a specific water-soluble polymer and polyurethane, but there is still room for improvement in providing a resin composition that achieves a high level of both mechanical properties and decorative properties and beautiful appearances.

[0006] An object of one aspect of the present invention is to solve the above problems and to provide a resin composition that achieves a high degree of compatibility between mechanical properties and decorative properties and aesthetic appearance, and a method for producing the same. [Means for solving the problem]

[0007] This disclosure encompasses the following items. [1] A resin composition comprising cellulose nanofibers, a resin, and a liquid polymer having a thermal decomposition onset temperature of greater than 200°C. [2] The resin composition according to item 1, wherein the liquid polymer is a liquid rubber. [3] The resin composition according to item 1 or 2, wherein the liquid polymer contains a diene rubber. [4] The resin composition according to any one of items 1 to 3, wherein the liquid polymer is at least one selected from the group consisting of polybutadiene, butadiene-styrene copolymer, polyisoprene, and polychloroprene. [5] The resin composition according to any one of items 1 to 4, wherein the liquid polymer has a number average molecular weight of 1,000 to 80,000. [6] The resin composition according to any one of items 1 to 5, wherein the liquid polymer has a viscosity of 100 mPa·s to 1,000,000 mPa·s at 25° C. [7] The resin composition according to any one of items 1 to 6, wherein the liquid polymer is a copolymer of a conjugated diene monomer and an aromatic vinyl monomer, and the amount of the aromatic vinyl monomer bonded to the conjugated diene monomer is 5 mol % to 70 mol %. [8] The resin composition according to any one of items 1 to 7, wherein the liquid polymer has a glass transition temperature of -150°C to 25°C. [9] The resin composition according to any one of items 1 to 8, wherein the cellulose nanofibers are chemically modified cellulose nanofibers.

[10] The resin composition according to item 9, wherein the chemically modified cellulose nanofibers are acylated cellulose nanofibers having an acyl substitution degree of 0.1 to 2.0.

[11] The resin composition according to any one of items 1 to 10, wherein the cellulose nanofibers have a number average fiber diameter of 2 nm to 1000 nm.

[12] The resin composition according to any one of items 1 to 11, wherein the cellulose nanofibers have a thermal decomposition onset temperature of 250°C or higher.

[13] The resin composition according to any one of items 1 to 12, wherein the liquid polymer is present in a form that penetrates at least a portion of the interface between the cellulose nanofibers and the resin.

[14] The resin composition according to any one of items 1 to 13, wherein the resin composition has a weight loss rate at 250°C of 1.5% or less.

[15] The thermal decomposition onset temperature T1 of the liquid polymer and the thermal decomposition onset temperature T2 of the cellulose nanofiber have the following relationship: (T1) ≧ (T2) The resin composition according to any one of items 1 to 14 above, which satisfies the above.

[16] The resin composition according to item 15, wherein the difference between T1 and T2, T1-T2, is 5°C or more.

[17] The resin composition according to any one of items 1 to 16, wherein the resin is a thermoplastic resin.

[18] The resin composition according to item 17, wherein the thermoplastic resin is at least one selected from the group consisting of polyamide-based resins, polyolefin-based resins, and polyacetal-based resins.

[19] The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T3 which is the melting point or the glass transition temperature + 70°C of the thermoplastic resin satisfy the following relationship: (T1)>(T3) 19. The resin composition according to item 17 or 18, which satisfies the above requirement.

[20] The resin composition according to item 19, wherein the thermoplastic resin is a crystalline thermoplastic resin, and the temperature T3 is a melting point of the thermoplastic resin.

[21] The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T4 which is the melting point or the glass transition temperature + 100°C of the thermoplastic resin satisfy the following relationship: (T1)>(T4) 20. The resin composition according to any one of items 17 to 19, which satisfies the above.

[22] The viscosity η50 of the liquid polymer at 50°C, the viscosity ηTm of the liquid polymer at a melting point of the thermoplastic resin + 20°C, and the melt viscosity ηr of the thermoplastic resin at a melting point of the thermoplastic resin + 20°C satisfy the following relationship: η50 / ηTm≧20, and 1≦ηr / η50≦1000 The resin composition according to any one of items 17 to 21 above, which satisfies the above.

[23] The thermoplastic resin is a polyolefin resin, The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyolefin resin + 20° C. have the following relationship: η50 / ηTm≧20 The resin composition according to any one of items 17 to 22 above, which satisfies the above.

[24] The thermoplastic resin is a polyolefin resin, The melt viscosity ηr of the polyolefin resin at a temperature 20° C. higher than the melting point of the polyolefin resin and the viscosity ηTm of the liquid polymer at a temperature 20° C. higher than the melting point of the polyolefin resin satisfy the following relationship: ηr / ηTm≦50000 The resin composition according to any one of items 17 to 23 above, which satisfies the above.

[25] The thermoplastic resin is a polyacetal resin; The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyacetal resin + 20° C. have the following relationship: η50 / ηTm≧20 The resin composition according to any one of items 17 to 22 above, which satisfies the above.

[26] The thermoplastic resin is a polyacetal resin, The melt viscosity ηr of the polyacetal resin at a melting point of the polyacetal resin + 20°C and the viscosity ηTm of the liquid polymer at a melting point of the polyacetal resin + 20°C have the following relationship: ηr / ηTm≦100000 The resin composition according to any one of items 17 to 22 and 25 above, which satisfies the above.

[27] The thermoplastic resin is a polyamide resin, The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyamide-based resin + 20° C. have the following relationship: η50 / ηTm≧80 The resin composition according to any one of items 17 to 22 above, which satisfies the above.

[28] The thermoplastic resin is a polyamide resin, The melt viscosity ηr of the polyamide-based resin at a temperature 20° C. higher than the melting point of the polyamide-based resin and the viscosity ηTm of the liquid polymer at a temperature 20° C. higher than the melting point of the polyamide-based resin satisfy the following relationship: ηr / ηTm≦50000 The resin composition according to any one of items 17 to 22 and 28 above, which satisfies the above.

[29] The resin composition according to any one of items 1 to 28, which does not contain a surfactant.

[30] The resin composition according to any one of items 1 to 29, further comprising 0.1 to 50 parts by mass of a dispersing aid relative to 100 parts by mass of the liquid polymer.

[31] A method for producing a resin composition according to any one of items 1 to 30, comprising the steps of: A method comprising heating and kneading a mixture comprising cellulose nanofibers, a resin, and a liquid polymer. Effect of the Invention

[0008] According to one aspect of the present invention, a resin composition that achieves a high degree of compatibility between mechanical properties and decorative properties and aesthetic appearance, and a method for producing the same can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The following is a detailed description of exemplary embodiments of the present invention (hereinafter, also referred to as the present embodiment), but the present invention is not limited to these embodiments. Note that, unless otherwise specified, the characteristic values ​​of the present disclosure are values ​​measured by the method described in the [Examples] section of the present disclosure or a method that is understood to be equivalent to the method by a person skilled in the art.

[0010] ≪Resin composition≫ A resin composition according to one embodiment of the present invention includes cellulose nanofibers, a resin, and a liquid polymer. In one embodiment, the liquid polymer has a thermal decomposition onset temperature of more than 200°C. Since the liquid polymer is liquid, it tends to have better cellulose nanofiber aggregation suppression ability than non-liquid materials, and since it is a polymer, it tends to have better heat resistance than non-polymer materials. Incorporating a liquid polymer into a resin composition containing cellulose nanofibers and a resin is advantageous in that the liquid polymer contributes to high cellulose nanofiber aggregation suppression ability and high heat resistance, thereby suppressing the generation of decomposition gases and the like during the processing of the resin composition. Such suppression of the generation of decomposition gases and the like is advantageous in improving the decorativeness and aesthetics by reducing the surface roughness of the resin composition.

[0011] The liquid polymer's high ability to inhibit cellulose nanofiber aggregation and high heat resistance as described above are achieved because the liquid polymer, unlike, for example, liquid non-polymeric materials (e.g., non-polymeric surfactants), does not have a structure with low heat resistance and has a hydrophobic structure that contributes to the dispersion of cellulose nanofibers in the resin.

[0012] While cellulose nanofibers are essentially hydrophilic due to their hydroxyl groups, the properties of the resins that are combined with the cellulose nanofibers to form the resin composition vary depending on the type of resin selected. It is not easy to disperse cellulose nanofibers well in a wide variety of resins, and methods such as combining a surfactant are used. However, surfactants are prone to thermal degradation due to heating when producing a resin composition (typically when cellulose nanofibers and a resin are heated and kneaded) and heating when processing the resin composition to form various molded bodies, and products generated by such thermal degradation may remain in the resin composition or molded body, thereby reducing mechanical properties, decorativeness, and / or appearance. The present inventors have investigated various methods for achieving good dispersion of cellulose nanofibers in a wide range of resins while eliminating the use of components that are prone to thermal degradation during the production and processing of the resin composition as much as possible. As a result, they have found that by combining a specific polymer that has fluidity at a certain temperature, i.e., a liquid polymer, with cellulose nanofibers, it is possible to disperse cellulose nanofibers as desired without substantially requiring the use of a surfactant. Liquid polymers tend to have superior thermal stability compared to non-polymers such as surfactants, and are therefore advantageous in that even if the resin composition is heated during production and processing, the mechanical properties, decorativeness and appearance of the resin composition and molded article are not adversely affected.

[0013] In a preferred embodiment, the liquid polymer is present in a form in which it has penetrated (i.e., has penetrated into) at least a portion of the interface between the cellulose nanofiber and the resin. In the present disclosure, the form in which the liquid polymer has penetrated into at least a portion of the interface between the cellulose nanofiber and the resin means that, in morphological observation using a scanning electron microscope and / or a transmission electron microscope, when the cellulose nanofiber, the resin, and the liquid polymer are distinguished by means of dyeing or the like, the liquid polymer is observed at the interface between the cellulose nanofiber and the resin. By being present between the cellulose nanofiber and the resin, such a liquid polymer contributes to good dispersion of the cellulose nanofiber in the resin. The liquid polymer does not have to cover the entire surface of the cellulose nanofiber, but preferably covers the entire surface. Preferred examples of each component of the resin composition will now be described.

[0014] <Cellulose nanofiber> The cellulose nanofiber may be obtained from various cellulose fiber raw materials selected from natural cellulose and regenerated cellulose. As the natural cellulose, wood pulp obtained from wood species (broadleaf or coniferous), non-wood pulp obtained from non-wood species (cotton, bamboo, hemp, bagasse, kenaf, cotton linters, sisal, straw, etc.), and cellulose fiber aggregates produced by animals (e.g., sea squirts), algae, and microorganisms (e.g., acetic acid bacteria) can be used. As the regenerated cellulose, regenerated cellulose fibers (viscose, cupra, Tencel, etc.), cellulose derivative fibers, and ultrafine threads of regenerated cellulose or cellulose derivatives obtained by electrospinning can be used. These raw materials can be adjusted, as necessary, by mechanical beating, fibrillation, and refinement using a grinder, refiner, etc. to adjust the fiber diameter, fiber length, fibrillation degree, etc., or by bleaching and refining using chemicals to adjust the content of components other than cellulose (acid-insoluble components such as lignin, alkali-soluble polysaccharides such as hemicellulose, etc.).

[0015] Cellulose nanofibers can be obtained by mechanically pulverizing cellulose raw materials in a dry or wet manner. This pulverization process can be carried out using a single device one or more times, or multiple devices can be used one or more times each. The equipment used for the pulp milling is not particularly limited, and examples thereof include high-speed rotation, colloid mill, high-pressure, roll mill, and ultrasonic types of equipment. Examples of equipment that can be used include high-pressure or ultra-high-pressure homogenizers, refiners, beaters, PFI mills, kneaders, dispersers, high-speed defibrators, grinders (stone-type grinders), ball mills, vibration mills, bead mills, conical refiners, disk-type refiners, single-axis, twin-axis, or multi-axis kneaders / extruders, homomixers under high-speed rotation, refiners, defibrators, beaters, friction grinders, high-shear fibrilators (e.g., Cavitron rotor / starter devices), dispergers, and homogenizers (e.g., microfluidizers), which act on pulp fibers with a metal or blade around a rotating shaft, or which use friction between pulp fibers themselves.

[0016] In one embodiment, the cellulose nanofibers can be obtained as a slurry, which can be prepared by dispersing and finely pulverizing cellulose fiber raw materials in water and / or other media (e.g., organic solvents, inorganic acids, bases, and / or ionic liquids).

[0017] The organic solvent used in the above-mentioned microparticulation treatment is not particularly limited, and examples thereof include alcohols having 1 to 20 carbon atoms, preferably 1 to 4 carbon atoms, such as methanol, ethanol, and propanol; glycol ethers having 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, such as methyl cellosolve and propylene glycol monomethyl ether; ethers having 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms, such as propylene glycol monomethyl ether, 1,2-dimethoxyethane, diisopropyl ether, tetrahydrofuran, and 1,4-dioxane; acetone, methyl ethyl ketone, methyl Examples of the solvent include ketones having 3 to 20 carbon atoms, preferably 3 to 6 carbon atoms, such as ethyl isobutyl ketone; linear or branched saturated or unsaturated hydrocarbons having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms; aromatic hydrocarbons such as benzene and toluene; halogenated hydrocarbons such as methylene chloride and chloroform; carboxylic acids having 1 to 20 carbon atoms, such as formic acid, acetic acid, and lactic acid; esters having 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, such as ethyl acetate and vinyl acetate; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone, and sulfur-containing solvents such as dimethylsulfoxide. These can be used alone or in combination of two or more kinds, but from the viewpoint of operability of the microparticulation treatment, alcohols having 1 to 6 carbon atoms, glycol ethers having 2 to 6 carbon atoms, ethers having 2 to 8 carbon atoms, ketones having 3 to 6 carbon atoms, lower alkyl ethers having 2 to 5 carbon atoms, carboxylic acids having 1 to 8 carbon atoms, esters having 2 to 6 carbon atoms, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and the like are preferred.

[0018] Examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid, etc., but from the viewpoint of defibration efficiency and handling, preferably, one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid are used.

[0019] Examples of bases include hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc., carbonates such as sodium carbonate, potassium carbonate, calcium carbonate, etc., ammonia, and organic amines such as triethylamine and triethanolamine, but from the viewpoints of defibration efficiency and handleability, one or more types selected from the group consisting of hydroxides, carbonates, and organic amines are preferred.

[0020] In the present disclosure, an ionic liquid refers to a liquid salt containing an organic ion in at least one of the cation moiety and the anion moiety, and the melting point of the ion alone is 100° C. or less. The cation moiety of the ionic liquid preferably has at least one cation selected from the group consisting of imidazolium cation, pyrrolidinium cation, piperidinium cation, morpholinium cation, pyridinium cation, quaternary ammonium cation, and phosphonium cation.

[0021] Among them, ionic liquids having an imidazolium skeleton, for example, ionic liquids represented by the following formula (1): [ka] (In the formula, R 1 and R 2 each independently represents an alkyl group or an allyl group having 1 to 8 carbon atoms, and X represents an anion. The imidazolium-based ionic liquid represented by the formula (I) is more preferable in that it has a relatively lower melting point than other ionic liquids, exists in a liquid state over a wide temperature range, has fluidity even at low temperatures, and is excellent in thermal stability. 1 and R 2 From the viewpoint of defibration property, the number of carbon atoms of each of the above is more preferably 4 or less, further preferably 3 or less, and most preferably 2 or less.

[0022] The anion components are halide ions (Cl - , Br - , I - etc.), carboxylate anions (e.g., carboxylate anions having a total of 1 to 3 carbon atoms, e.g., C 2 H 5 CO 2- , C.H. 3 CO 2 - , HCO 2 - etc.), pseudohalide ions (i.e., ions that are monovalent and have properties similar to those of halide ions, e.g., CN - , SCN - , OCN - , O.N.C. - , N 3 - Examples of anions that can be used include anions of sulfonate, organic sulfonate (e.g., methanesulfonate), phosphate (e.g., ethyl phosphate, methyl phosphate, hexafluorophosphate), borate (e.g., tetrafluoroborate), and perchlorate, and from the viewpoint of defibration ability, halide ions and carboxylate anions are preferred.

[0023] Examples of imidazolium ionic liquids include 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium formate, 1-allyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium diethyl phosphate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium propionate, 1-propyl-3-methylimidazolium chloride, and 1-propyl-3-methylimidazolium bromide.

[0024] Although cellulose fiber raw materials can be defibrated using only ionic liquids, when there is a risk that the cellulose nanofibers may be dissolved due to the ionic liquid having too high a dissolving power for cellulose, it is preferable to add water and / or an organic solvent to the ionic liquid. The type of organic solvent to be added may be appropriately selected taking into consideration the compatibility with the ionic liquid, the affinity with cellulose, the solubility of the mixed solvent in the cellulose fiber raw materials, the viscosity, etc., and is preferably one or more selected from the group consisting of N,N-dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidone, dimethylsulfoxide, acetonitrile, methanol, and ethanol.

[0025] The total amount of water and / or other medium used in the micronization treatment is not particularly limited as long as it is an effective amount capable of dispersing the cellulose fiber raw material, but is preferably at least 1 time by mass, more preferably at least 10 times by mass, even more preferably at least 50 times by mass, and is preferably not more than 10,000 times by mass, more preferably not more than 5,000 times by mass, even more preferably not more than 2,000 times by mass, and particularly preferably not more than 1,000 times by mass, relative to the cellulose fiber raw material.

[0026] Since the cellulose fiber raw material contains alkali soluble matter and sulfuric acid insoluble matter (lignin, etc.), the alkali soluble matter and sulfuric acid insoluble matter may be reduced by a purification process such as delignification by cooking and a bleaching process. On the other hand, the purification process such as delignification by cooking and the bleaching process cut the molecular chains of cellulose, changing the weight average molecular weight and number average molecular weight, so it is desirable to control the purification process and bleaching process of the cellulose fiber raw material so that the weight average molecular weight of the cellulose nanofiber and the ratio of the weight average molecular weight to the number average molecular weight are within an appropriate range.

[0027] In addition, there is a concern that the molecular weight of cellulose nanofibers will be reduced by the refining process such as delignification by cooking and the bleaching process, and that the cellulose fiber raw material will be altered to increase the proportion of alkali-soluble matter. Since alkali-soluble matter has poor heat resistance, it is desirable to control the refining process and bleaching process of the cellulose fiber raw material so that the amount of alkali-soluble matter contained in the cellulose fiber raw material is within a certain range or less.

[0028] In one embodiment, the cellulose fiber raw material may be chemically modified, and inorganic esters such as nitrate esters, sulfate esters, phosphate esters, silicate esters, and borates, organic esters such as acetylation and propionylation, ethers such as methyl ether, hydroxyethyl ether, hydroxypropyl ether, hydroxybutyl ether, carboxymethyl ether, and cyanoethyl ether, and TEMPO oxides obtained by oxidizing the primary hydroxyl groups of cellulose can be used as the cellulose fiber raw material.

[0029] [Number average fiber diameter and L / D ratio] In one aspect, the number average fiber diameter of the cellulose nanofibers is preferably 2 to 1000 nm from the viewpoint of obtaining a good effect of improving physical properties by the cellulose nanofibers. The number average fiber diameter of the cellulose nanofibers is more preferably 4 nm or more, or 5 nm or more, or 10 nm or more, or 15 nm or more, or 20 nm or more, and more preferably 900 nm or less, or 800 nm or less, or 700 nm or less, or 600 nm or less, or 500 nm or less, or 400 nm or less, or 300 nm or less, or 200 nm or less.

[0030] From the viewpoint of satisfactorily improving the mechanical properties of a resin composition containing cellulose nanofibers with a small amount of cellulose nanofibers, the number average fiber length (L) / number average fiber diameter (D) ratio of the cellulose nanofibers is preferably 30 or more, or 50 or more, or 80 or more, or 100 or more, or 120 or more, or 150 or more. There are no particular upper limits, but from the viewpoint of handleability, it is preferably 5,000 or less, or 3,000 or less, or 2,000 or less, or 1,000 or less.

[0031] In one embodiment, the number average fiber diameter (D), number average fiber length (L), and L / D ratio of the cellulose nanofibers of the present disclosure are values ​​measured using a scanning electron microscope (SEM) according to the following procedure. The aqueous dispersion of cellulose fibers is replaced with tert-butanol, diluted to 0.001 to 0.1% by mass, and dispersed using a high-shear homogenizer (e.g., IKA, product name "Ultra Turrax T18") under processing conditions: rotation speed 15,000 rpm x 3 minutes. The sample is cast on an osmium-deposited silicon substrate and air-dried to obtain a measurement sample, which is measured using a high-resolution scanning electron microscope (SEM). Specifically, the length (L) and diameter (D) of 100 randomly selected fibrous substances are measured in an observation field where the magnification is adjusted so that at least 100 fibrous substances are observed, and the ratio (L / D) is calculated. 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 for the cellulose fibers.

[0032] [BET specific surface area] In one embodiment, the BET specific surface area of ​​the cellulose nanofiber is preferably 1 m from the viewpoint of improving the dispersibility of the cellulose nanofiber in the resin composition. 2 / g or more, or 3m 2 / g or more, or 5m 2 / g or more, or 8m 2 / g or more, or 10m 2 / g or more, or 12m 2 / g or more, and from the viewpoint of ease of production of the dried product, it is preferably 50m 2 / g or less, or 40m 2 / g or less, or 30m 2 / g or less, or 25m 2 / g or less, or 20m 2 The specific surface area is measured by drying approximately 0.2 g of cellulose nanofiber at 120°C for 5 hours under vacuum using a specific surface area / pore size distribution measuring device (e.g., Nova-4200e, manufactured by Quantachrome Instruments), and then measuring the amount of adsorption of nitrogen gas at the boiling point of liquid nitrogen in terms of the relative vapor pressure (P / P 0 ) was measured at five points in the range of 0.05 to 0.2 (multipoint method), and then the BET specific surface area (m 2 / g)

[0033] [Crystallization degree] The crystallinity of the cellulose nanofibers is preferably 55% or more. When the crystallinity is in this range, the mechanical properties (strength, dimensional stability) of the cellulose itself are high, so that when the cellulose nanofibers are dispersed in a resin, the strength and dimensional stability of the resin composition tend to be high. A more preferable lower limit of the crystallinity is 60%, even more preferably 70%, and most preferably 80%. There is no particular upper limit for the crystallinity of the cellulose nanofibers, and the higher the better, but from the viewpoint of production, a preferable upper limit is 99%.

[0034] The degree of crystallinity here, when the cellulose is cellulose type I crystal (derived from natural cellulose), is calculated from the diffraction pattern (2θ / deg. is 10 to 30) obtained by measuring a sample by wide-angle X-ray diffraction using the Segal method, according to the following formula: Crystallinity (%)=[I (200) -I (amorphous) ] / I (200) ×100 I (200) : Diffraction peak intensity due to 200 plane (2θ=22.5°) in cellulose I crystals I (amorphous) : The halo peak intensity due to the amorphous phase in cellulose I crystals, which is the peak intensity at an angle 4.5° lower than the diffraction angle of the 200 plane (2θ=18.0°)

[0035] When the cellulose is cellulose II type crystal (derived from regenerated cellulose), the degree of crystallinity can be calculated from the absolute peak intensity h0 at 2θ=12.6° assigned to the (110) plane peak of cellulose II type crystal in wide-angle X-ray diffraction and the peak intensity h1 from the baseline at this interplanar spacing, according to the following formula: Crystallinity (%) =h1 / h0 ×100

[0036] [Crystal polymorphism] Known crystalline polymorphs of cellulose include types I, II, III, and IV, of which types I and II are particularly widely used, and types III and IV have been obtained on a laboratory scale but are not widely used on an industrial scale. The cellulose nanofibers of the present disclosure are preferably cellulose nanofibers containing cellulose type I crystals or cellulose type II crystals, since they have relatively high structural mobility and, by dispersing the cellulose nanofibers in a resin, a resin composition can be obtained that has a lower linear expansion coefficient and is superior in strength and elongation during tensile and bending deformation, and more preferably cellulose nanofibers containing cellulose type I crystals and having a crystallinity of 55% or more.

[0037] [Degree of polymerization] In addition, the degree of polymerization of the cellulose nanofiber is preferably 100 or more, more preferably 150 or more, more preferably 200 or more, more preferably 300 or more, more preferably 400 or more, more preferably 450 or more, and preferably 3500 or less, more preferably 3300 or less, more preferably 3200 or less, more preferably 3100 or less, and more preferably 3000 or less.

[0038] From the viewpoint of processability and mechanical property expression, it is desirable that the degree of polymerization of the cellulose nanofiber is within the above-mentioned range. From the viewpoint of processability, it is preferable that the degree of polymerization is not too high, and from the viewpoint of mechanical property expression, it is desirable that the degree of polymerization is not too low.

[0039] The degree of polymerization of cellulose nanofibers refers to the average degree of polymerization measured according to the reduced specific viscosity method using a copper ethylenediamine solution described in the Verification Test (3) of the "15th Revised Japanese Pharmacopoeia Commentary (published by Hirokawa Shoten)." Incidentally, the degree of polymerization of chemically modified cellulose nanofibers may not be calculated accurately due to the presence of chemically modifying groups. In such cases, the degree of polymerization of the cellulose nanofiber immediately before chemical modification, which is the raw material for the chemically modified cellulose nanofiber, or the raw cellulose fiber immediately before chemical modification, may be regarded as the degree of polymerization of the chemically modified cellulose nanofiber.

[0040] [Mw, Mn, Mw / Mn] In one embodiment, the weight average molecular weight (Mw) of the cellulose nanofiber is 100,000 or more, or 200,000 or more. In one embodiment, the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight (Mn) is 6 or less, or 5.4 or less. The larger the weight average molecular weight, the fewer the number of terminal groups of the cellulose molecule. In addition, 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, the smaller the Mw / Mn, the fewer the number of terminals of the cellulose molecule. Since the terminals of the cellulose molecules are the starting points of thermal decomposition, cellulose nanofibers with particularly high heat resistance can be obtained when the cellulose molecules of the cellulose nanofibers not only have a large weight average molecular weight but also have a narrow molecular weight distribution width at the same time. The weight average molecular weight (Mw) of the cellulose nanofiber may be, for example, 600,000 or less, or 500,000 or less, from the viewpoint of the availability of cellulose fiber raw materials. From the viewpoint of ease of production of cellulose nanofibers, the ratio (Mw / Mn) of weight average molecular weight to number average molecular weight (Mn) may be, for example, 1.5 or more, or 2 or more. Mw can be controlled to the above range by selecting a cellulose fiber raw material having an Mw appropriate for the purpose, by appropriately performing physical treatment and / or chemical treatment on the cellulose fiber raw material within an appropriate range, etc. Mw / Mn can also be controlled to the above range by selecting a cellulose fiber raw material having an Mw / Mn appropriate for the purpose, by appropriately performing physical treatment and / or chemical treatment on the cellulose fiber raw material within an appropriate range, etc. Each of the Mw and Mw / Mn of the cellulose fiber raw material may be within the above range in one embodiment. In both the control of Mw and the control of Mw / Mn, examples of the physical treatment include physical treatments that apply mechanical forces such as dry or wet grinding using a microfluidizer, ball mill, disk mill, etc., and impact, shear, friction, etc. using a crusher, homomixer, high-pressure homogenizer, ultrasonic device, etc., and examples of the chemical treatments include digestion, bleaching, acid treatment, enzyme treatment, regenerated cellulose, etc. It should be noted that the Mw, Mn, and Mw / Mn of chemically modified cellulose nanofibers may not be calculated accurately due to the presence of chemically modifying groups. In this case, the Mw, Mn, and Mw / Mn of the cellulose nanofiber immediately before chemical modification, which is the raw material for the chemically modified cellulose nanofiber, or the cellulose fiber raw material immediately before chemical modification, may be regarded as the Mw, Mn, and Mw / Mn of the chemically modified cellulose nanofiber.

[0041] The weight average molecular weight and number average molecular weight of the cellulose nanofiber referred to here are values ​​obtained by dissolving the cellulose nanofiber in N,N-dimethylacetamide containing added lithium chloride and then performing gel permeation chromatography using N,N-dimethylacetamide as a solvent.

[0042] [Control of polymerization degree and molecular weight] Methods for controlling the degree of polymerization (i.e., average degree of polymerization) or molecular weight of cellulose nanofibers include hydrolysis. Hydrolysis promotes depolymerization of amorphous cellulose inside the cellulose nanofibers, decreasing the average degree of polymerization. At the same time, hydrolysis removes impurities such as hemicellulose and lignin in addition to the above-mentioned amorphous cellulose, making the inside of the fiber more porous.

[0043] The hydrolysis method is not particularly limited, and examples thereof include acid hydrolysis, alkali hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used alone or in combination of two or more. In the acid hydrolysis method, for example, α-cellulose obtained as pulp from a fibrous plant is used as a cellulose fiber raw material, and this is dispersed in an aqueous medium, and an appropriate amount of protonic acid, carboxylic acid, Lewis acid, heteropolyacid, etc. is added, and the mixture is heated while stirring, so that the average degree of polymerization can be easily controlled. The reaction conditions such as temperature, pressure, and time at this time vary depending on the cellulose type, cellulose concentration, acid type, acid concentration, etc., but are appropriately adjusted so that the desired average degree of polymerization is achieved. For example, a condition in which a mineral acid aqueous solution of 2% by mass or less is used and cellulose nanofibers are treated at 100°C or higher under pressure for 10 minutes or more can be mentioned. Under these conditions, the catalyst component such as acid penetrates into the inside of the cellulose nanofiber, promoting hydrolysis, reducing the amount of catalyst component used, and making subsequent purification easier. The dispersion of the cellulose fiber raw material during hydrolysis may contain, in addition to water, a small amount of an organic solvent within a range that does not impair the effects of the present invention.

[0044] [Alkali-soluble polysaccharides and acid-insoluble components] Alkali-soluble polysaccharides such as hemicellulose and acid-insoluble components such as lignin exist between the microfibrils and between the microfibril bundles of cellulose nanofibers. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and plays a role in connecting the microfibrils by hydrogen bonding with cellulose. Lignin is a compound with an aromatic ring, and is known to be covalently bonded to hemicellulose in the cell walls of plants.

[0045] Alkali-soluble polysaccharides that may be contained in cellulose nanofibers include hemicellulose, β-cellulose, and γ-cellulose. Alkali-soluble polysaccharides are understood by those skilled in the art as components obtained as the alkali-soluble portion of holocellulose obtained by solvent extraction and chlorine treatment of plants (e.g., wood) (i.e., components obtained by removing α-cellulose from holocellulose). Alkali-soluble polysaccharides are polysaccharides containing hydroxyl groups and have poor heat resistance, and may cause inconveniences such as decomposition when exposed to heat, yellowing during thermal aging, and a decrease in strength of cellulose nanofibers. Therefore, it is preferable that the content of alkali-soluble polysaccharides in cellulose nanofibers is low.

[0046] In one aspect, the average content of alkali-soluble polysaccharides in the cellulose nanofibers is preferably 20% by mass or less, 18% by mass or less, 15% by mass or less, or 12% by mass or less, relative to 100% by mass of the cellulose nanofibers, from the viewpoint of maintaining the mechanical strength of the cellulose nanofibers during melt-kneading and suppressing yellowing. From the viewpoint of ease of production of the cellulose nanofibers, the above content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more.

[0047] The average alkali-soluble polysaccharide content can be determined by the method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pages 92-97, 2000), by subtracting the α-cellulose content from the holocellulose content (Wise method). This method is understood in the industry as a method for measuring the amount of hemicellulose. The alkali-soluble polysaccharide content is calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide contents is taken as the average alkali-soluble polysaccharide content. The alkali-soluble polysaccharide content of chemically modified cellulose nanofibers may not be calculated accurately due to the presence of chemical modification groups. In this case, the average alkali-soluble polysaccharide content of the cellulose nanofibers immediately before chemical modification, which are the raw material for chemically modified cellulose nanofibers, or the cellulose fiber raw material immediately before chemical modification, may be regarded as the average alkali-soluble polysaccharide content of the chemically modified cellulose nanofibers.

[0048] Those skilled in the art will understand that acid-insoluble components that cellulose nanofibers may contain are insoluble components that remain after a defatted sample obtained by solvent extraction of a plant (e.g., wood) is treated with sulfuric acid. Specifically, the acid-insoluble component is lignin derived from aromatic compounds, but is not limited thereto. Since the acid-insoluble component is often colored by itself and may cause inconveniences such as impairing the appearance of the resin composition and causing yellowing during thermal aging, it is preferable that the average content of acid-insoluble components in the cellulose nanofibers is low.

[0049] In one aspect, the average content of acid-insoluble components in the cellulose nanofibers is preferably 10% by mass or less, 5% by mass or less, or 3% by mass or less, relative to 100% by mass of the cellulose nanofibers, from the viewpoint of avoiding a decrease in heat resistance of the cellulose nanofibers and the associated discoloration. From the viewpoint of ease of production of the cellulose nanofibers, the above content may be 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more.

[0050] The average acid-insoluble content is determined as a quantity of acid-insoluble components using the Clason method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pages 92-97, 2000). This method is understood in the industry 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 glass fiber filter paper, and the resulting residue corresponds to the acid-insoluble components. The acid-insoluble component content is calculated from the weight of the acid-insoluble components, and the number average of the acid-insoluble component contents calculated for the three samples is taken as the average acid-insoluble component content. The average acid-insoluble component content of chemically modified cellulose nanofibers may not be calculated accurately due to the presence of chemical modification groups. In this case, the average alkali-soluble polysaccharide content of the cellulose nanofibers immediately before chemical modification, which are the raw material for chemically modified cellulose nanofibers, or the cellulose fiber raw material immediately before chemical modification, may be considered as the average alkali-soluble polysaccharide content of the chemically modified cellulose nanofibers.

[0051] [Thermal decomposition onset temperature (T D )] The thermal decomposition temperature of cellulose nanofiber (T D ) is, in one aspect, preferably 250° C. or higher, or 260° C. or higher, or 270° C. or higher, or 275° C. or higher, or 280° C. or higher, or 285° C. or higher, from the viewpoint of avoiding thermal degradation during melt-kneading and being able to exert mechanical strength. The higher the thermal decomposition onset temperature, the more preferable it is, but from the viewpoint of ease of production of cellulose nanofibers, it may be, for example, 320° C. or lower, 310° C. or lower, or 300° C. or lower.

[0052] [Temperature at 1% weight loss (T 1% ), 250℃ weight loss rate (T 250℃ )] The temperature at which the cellulose nanofiber loses 1 wt% weight (T 1% From the viewpoint of avoiding thermal deterioration during melt-kneading and exhibiting mechanical strength, in one aspect, the temperature is preferably 260° C. or higher, 270° C. or higher, 275° C. or higher, 280° C. or higher, 285° C. or higher, or 290° C. or higher.1% The higher the temperature, the more preferable; however, from the viewpoint of ease of production of cellulose nanofibers, the temperature may be, for example, 330° C. or less, 320° C. or less, or 310° C. or less.

[0053] Weight loss rate of cellulose nanofiber at 250°C (T 250℃ From the viewpoint of avoiding thermal deterioration during melt-kneading and exhibiting mechanical strength, in one aspect, T is preferably 15% or less, or 12% or less, or 10% or less, or 8% or less, or 6% or less, or 5% or less, or 4% or less, or 3% or less. 250℃ The lower the better, but from the viewpoint of ease of production of cellulose nanofibers, it may be, for example, 0.1% or more, or 0.5% or more, or 0.7% or more, or 1.0% or more.

[0054] In this disclosure, T D is a value obtained from a graph in which the horizontal axis is temperature and the vertical axis is the weight residual rate % in thermogravimetry (TG) analysis under nitrogen flow. Cellulose nanofibers are heated from room temperature to 150°C at a heating rate of 10°C / min in a nitrogen flow of 100 ml / min, and then held at 150°C for 1 hour, after which they are heated to 450°C at a heating rate of 10°C / min. Starting from the weight at 150°C (a state where most moisture has been removed) (weight loss of 0 wt%), the temperature at which 1 wt% weight loss occurs (T 1% ) and the temperature at which the weight loss reaches 2 wt% (T 2% The temperature at the point where this line intersects with the horizontal line (baseline) that passes through the starting point of the weight loss of 0 wt% is called T D It is defined as:

[0055] 1% weight loss temperature (T 1% ) is the above T D This is the temperature at which the weight loss reaches 1% by weight, starting from the weight at 150°C, when the temperature is continued to be increased using the method described above.

[0056] Weight loss rate of cellulose nanofiber at 250°C (T 250℃) is the weight loss rate when cellulose nanofibers are held at 250°C under nitrogen flow for 2 hours in TG analysis. The cellulose nanofibers are heated from room temperature to 150°C at a rate of 10°C / min in a nitrogen flow of 100 ml / min, held at 150°C for 1 hour, then heated from 150°C to 250°C at a rate of 10°C / min, and held at 250°C for 2 hours. The weight W0 at the time when 250°C is reached is taken as the starting point, and the weight after holding at 250°C for 2 hours is taken as W1, and is calculated using the following formula. Weight change rate at 250℃ (%): (W1-W0) / W0×100

[0057] [Porous sheet] The properties of cellulose nanofiber (crystallinity, crystalline polymorphism, degree of polymerization, Mw, Mn, Mw / Mn, average content of alkali-soluble polysaccharides, average content of acid-insoluble components, T D , T 1% , T 250℃ The measurements of the above may vary greatly depending on the shape of the measurement sample. In order to perform stable and reproducible measurements, a distortion-free porous sheet is used as the measurement sample. The porous sheet is prepared as follows.

[0058] First, a concentrated cake of cellulose nanofibers with a solid content of 10% by mass or more is added to tert-butanol, and a dispersion process is then performed using a mixer or the like until no aggregates remain. The concentration is adjusted to 0.5% by mass for 0.5 g of cellulose nanofiber solids. 100 g of the resulting tert-butanol dispersion is filtered on filter paper. The filtered material is not peeled off from the filter paper, but is sandwiched together with the filter paper between two sheets of larger filter paper, and dried for 5 minutes in an oven at 150°C while pressing down the edges of the larger filter paper with a weight. The filter paper is then peeled off to obtain a porous sheet with little distortion. When the air resistance R of this sheet is 10 g / m2, the sheet weight is 10 g / m2. 2 A porous sheet with a permeability of 100 sec / 100 ml or less is used as the measurement sample.

[0059] The air permeability resistance R was measured by measuring the basis weight W (g / m2) of a porous sheet sample left to stand for one day in an environment of 23°C and 50% RH. 2 ), and then the air resistance R (sec / 100ml) is measured using an Oken air resistance tester (e.g., Asahi Seiko Co., Ltd., Model EG01). 2 Calculate the value per unit area. Weight 10g / m 2 Air resistance per unit (sec / 100ml) = R / W x 10

[0060] [Physical properties of cellulose nanofibers in resin composition] Various physical properties of cellulose nanofibers in the resin composition (number average fiber length, number average fiber diameter, L / D ratio, crystallinity, crystal polymorphism, polymerization degree, Mw, Mn, Mw / Mn, average content of alkali-soluble polysaccharides, average content of acid-insoluble components, T D , T 1% , T 250℃ (and DS, DSs, DS heterogeneity ratio, and coefficient of variation of DS heterogeneity ratio, etc., described below) are analyzed by the following method. The resin components in the resin composition are dissolved in an organic or inorganic solvent capable of dissolving the resin components of the resin composition, the cellulose nanofibers are separated, thoroughly washed with the solvent, and the solvent is replaced with tert-butanol. The cellulose nanofiber tert-butanol slurry is then analyzed using the same measurement method as above, and various physical properties of the cellulose nanofibers in the resin composition are calculated.

[0061] [Chemical modification] The cellulose nanofibers may be chemically modified cellulose nanofibers (also referred to as chemically modified cellulose nanofibers). The cellulose nanofibers may be chemically modified in advance, for example, at the stage of raw cellulose fiber material, during or after defibration treatment, or may be chemically modified during or after preparation of a slurry as a dispersion, or during or after the drying and granulation process.

[0062] As a modification agent for cellulose nanofibers, a compound that reacts with the hydroxyl groups of cellulose can be used, such as an esterification agent, an etherification agent, and a silylating agent. In a preferred embodiment, the chemical modification is acylation using an esterification agent, and particularly preferably acetylation. As the esterification agent, acid halides, acid anhydrides, vinyl carboxylates, and carboxylic acids are preferred.

[0063] The acid halide may be at least one selected from the group consisting of compounds represented by 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 is Cl, Br, or I. Specific examples of acid halides include, but are not limited to, acetyl chloride, acetyl bromide, acetyl iodide, propionyl chloride, propionyl bromide, propionyl iodide, butyryl chloride, butyryl bromide, butyryl iodide, benzoyl chloride, benzoyl bromide, and benzoyl iodide. Among them, acid chlorides can be preferably used in terms of reactivity and handling. In addition, in the reaction of acid halides, one or more alkaline compounds may be added to act as a catalyst and neutralize the by-product acidic substances. Specific examples of alkaline compounds include, but are not limited to, tertiary amine compounds such as triethylamine and trimethylamine; and nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine.

[0064] As the acid anhydride, any suitable acid anhydride can be used. For example, Saturated aliphatic monocarboxylic acid anhydrides, such as acetic acid, propionic acid, (iso)butyric acid, and valeric acid; unsaturated aliphatic monocarboxylic acid anhydrides, such as (meth)acrylic acid and oleic acid; Alicyclic monocarboxylic acid anhydrides such as cyclohexanecarboxylic acid and tetrahydrobenzoic acid; Aromatic monocarboxylic acid anhydrides such as benzoic acid and 4-methylbenzoic acid; Examples of dibasic carboxylic acid anhydrides include saturated aliphatic dicarboxylic acid anhydrides such as succinic anhydride and adipic acid, unsaturated aliphatic dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, alicyclic dicarboxylic acid anhydrides such as 1-cyclohexene-1,2-dicarboxylic acid anhydride, hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride, and aromatic dicarboxylic acid anhydrides such as phthalic anhydride and naphthalic anhydride; Examples of polybasic carboxylic acid anhydrides having three or more bases include polycarboxylic acids (anhydrides) such as trimellitic anhydride and pyromellitic anhydride. In addition, in the reaction of the acid anhydride, a catalyst may be used, for example, 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 represents a semimetal element such as B, As, or Ge, or a base metal element such as Al, Bi, or In, or a transition metal element such as Ti, Zn, or Cu, or a lanthanoid element, n is an integer corresponding to the atomic valence of M and represents 2 or 3, and Y represents a halogen atom, OAc, OCOCF, or the like). 3 , ClO 4 , SbF 6 , P.F. 6 or OSO 2 CF 3 (OTf). Alternatively, one or more alkaline compounds such as triethylamine and pyridine may be added.

[0065] The vinyl carboxylate may be represented by the following formula: R-COO-CH=CH 2 {wherein R is any one of an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, and an aryl group having 6 to 24 carbon atoms.} is preferred. The vinyl carboxylate is more preferably at least one selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate, divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl octylate, vinyl benzoate, and vinyl cinnamate. In the esterification reaction with a vinyl carboxylate, one or more catalysts selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal hydrogencarbonates, primary to tertiary amines, quaternary ammonium salts, imidazole and derivatives thereof, pyridine and derivatives thereof, and alkoxides may be added.

[0066] Examples of the alkali metal hydroxides and alkaline earth metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide, etc. Examples of the alkali metal carbonates, alkaline earth metal carbonates, and alkali metal hydrogen carbonates include lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate, etc.

[0067] The primary, secondary and tertiary amines refer to primary, secondary and tertiary amines, and specific examples thereof 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-dimethylcyclohexylamine and triethylamine.

[0068] Examples of imidazole and its derivatives include 1-methylimidazole, 3-aminopropylimidazole, and carbonyldiimidazole.

[0069] Examples of pyridine and its derivatives include N,N-dimethyl-4-aminopyridine and picoline.

[0070] Examples of the alkoxide include sodium methoxide, sodium ethoxide, and potassium t-butoxide.

[0071] The carboxylic acid may be at least one selected from the group consisting of compounds represented by the following formulas: R-COOH (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.)

[0072] Specific examples of carboxylic acids include at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, caproic acid, cyclohexane carboxylic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, pivalic acid, methacrylic acid, crotonic acid, octylic acid, benzoic acid, and cinnamic acid.

[0073] Among these carboxylic acids, at least one selected from the group consisting of acetic acid, propionic acid, and butyric acid, and particularly acetic acid, is preferred from the viewpoint of reaction efficiency. In the reaction of carboxylic acid, a catalyst may be 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 represents a semimetallic element such as B, As, or Ge, or a base metal element such as Al, Bi, or In, or a transition metal element such as Ti, Zn, or Cu, or a lanthanoid element, n is an integer corresponding to the atomic valence of M and represents 2 or 3, and Y represents a halogen atom, OAc, OCOCF, or the like). 3 , ClO 4 , SbF6 , P.F. 6 Or OSO 2 CF 3 (OTf). Alternatively, one or more alkaline compounds such as triethylamine and pyridine may be added.

[0074] Among these esterification reactants, at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, vinyl acetate, vinyl propionate, vinyl butyrate, and acetic acid, and among these, acetic anhydride and vinyl acetate are preferred from the viewpoint of reaction efficiency.

[0075] [Acyl Substitution Degree (DS)] When cellulose nanofibers are chemically modified (for example, by hydrophobization such as acylation), the dispersibility of the cellulose nanofibers in the resin tends to be good, but the cellulose nanofibers of the present disclosure can exhibit good dispersibility in the resin even when unsubstituted or with a low degree of substitution by combining with a liquid polymer. When the cellulose nanofibers are esterified cellulose nanofibers, the degree of acyl substitution (DS) is preferably 0.1 or more, or 0.2 or more, or 0.25 or more, or 0.3 or more, or 0.5 or more in terms of obtaining esterified cellulose nanofibers with a high thermal decomposition onset temperature, and is preferably 2.0 or less, or 1.8 or less, or 1.5 or less, or 1.2 or less, or 1.0 or less, or 0.8 or less, or 0.7 or less, or 0.6 or less, or 0.5 or less in terms of obtaining esterified cellulose nanofibers with a high thermal decomposition onset temperature because an unmodified cellulose skeleton remains in the esterified cellulose nanofibers.

[0076] When the modification group of the chemically modified cellulose nanofiber is an acyl group, the degree of acyl substitution (DS) can be calculated from the peak intensity ratio of the peak derived from the acyl group to the peak derived from the cellulose skeleton from the reflection infrared absorption spectrum of the esterified cellulose nanofiber. The peak of the absorption band of C=O based on the acyl group is at 1730 cm -1The absorption band of CO based on the cellulose backbone appears at 1030 cm -1 The DS of esterified cellulose nanofibers was calculated by plotting a correlation graph between the DS obtained from solid-state NMR measurements of esterified cellulose nanofibers (described below) and the modification ratio (IR index 1030), which is defined as the ratio of the peak intensity of the absorption band of C=O based on acyl groups to the peak intensity of the absorption band of CO in the cellulose backbone chain, and then calculating the calibration curve from the correlation graph. Degree of substitution DS = 4.13 × IR index (1030) It can be found by using

[0077] The method for calculating the DS of esterified cellulose nanofibers using solid-state NMR is as follows: 13 C solid-state NMR measurement was performed, and the intensity can be calculated using the area intensity (Inf) of a signal assigned to one carbon atom derived from the modifying group relative to the total area intensity (Inp) of signals assigned to carbons C1-C6 derived from the pyranose ring of cellulose, which appear in the range from 50 ppm to 110 ppm, using the following formula. DS = (Inf) x 6 / (Inp) For example, if the modifying group is an acetyl group, -CH 3 The signal at 23 ppm assigned to the Use 13 The conditions for the C solid-state NMR measurement are, for example, as follows: Equipment:Bruker Biospin Avance500WB Frequency: 125.77MHz Measurement method: DD / MAS method Waiting time: 75sec NMR sample tube: 4mmφ Accumulation times: 640 times (approx. 14 hours) MAS: 14,500Hz Chemical shift reference: glycine (external reference: 176.03 ppm)

[0078] The DS heterogeneity ratio (DSs / DSt), defined as the ratio of the degree of modification (DSs) of the fiber surface to the degree of modification (DSt) of the entire fiber of the chemically modified cellulose nanofiber (which is synonymous with the above-mentioned degree of acyl substitution (DS)), is preferably 1.05 or more. The larger the value of the DS heterogeneity ratio, the more pronounced the sheath-core-like heterogeneous structure (i.e., a structure in which the fiber surface is highly chemically modified while the fiber center retains a cellulose structure close to the original unmodified structure), and while maintaining high tensile strength and dimensional stability derived from cellulose, it is possible to improve the affinity with the resin when composited with the resin and to improve the dimensional stability of the resin composition. The DS heterogeneity ratio is more preferably 1.1 or more, or 1.2 or more, or 1.3 or more, or 1.5 or more, or 2 or more, and from the viewpoint of ease of production of the chemically modified cellulose nanofiber, it is preferably 30 or less, or 20 or less, or 10 or less, or 6 or less, or 4 or less, or 3 or less. The value of DSs varies depending on the degree of modification of the esterified cellulose nanofiber, but as an example, it is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, even more preferably 0.5 or more, and preferably 3.0 or less, more preferably 2.5 or less, particularly preferably 2.0 or less, even 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 the acyl substituent (DS).

[0079] The smaller the coefficient of variation (CV) of the DS heterogeneity ratio of the chemically modified cellulose nanofiber, the smaller the variation in various physical properties of the resin composition, and therefore the more preferable. The coefficient of variation is preferably 50% or less, or 40% or less, or 30% or less, or 20% or less. The coefficient of variation can be further reduced, for example, by a method in which a cellulose fiber raw material is defibrated and then chemically modified to obtain a chemically modified cellulose nanofiber (i.e., a sequential method), whereas it can be increased by a method in which defibration and chemical modification of the cellulose fiber raw material are performed simultaneously (i.e., a simultaneous method). Although the mechanism of this action is not clear, in the simultaneous method, chemical modification is more likely to proceed in the thin fibers generated in the early stage of defibration, and when hydrogen bonds between cellulose microfibrils are reduced by chemical modification, defibration proceeds further, which is thought to result in an increase in the coefficient of variation of the DS heterogeneity ratio.

[0080] The coefficient of variation (CV) of the DS heterogeneity ratio is calculated by taking 100 g of an aqueous dispersion of chemically modified cellulose nanofiber (solid content of 10 mass% or more) and freeze-pulverizing 10 g portions to use as measurement samples. The DS heterogeneity ratio is calculated from the DSt and DSs of the 10 samples, and then the standard deviation (σ) and arithmetic mean (μ) of the DS heterogeneity ratio among the obtained 10 samples are used to calculate the coefficient of variation (CV) of the DS heterogeneity ratio using the following formula. DS heterogeneity ratio = DSs / DSt Coefficient of variation (%) = standard deviation σ / arithmetic mean μ × 100

[0081] The DSs is calculated as follows. That is, the esterified cellulose nanofibers powdered by freeze-pulverization are placed on a dish-shaped sample stage with a diameter of 2.5 mm, the surface is pressed down to make it flat, and then measurement is performed by X-ray photoelectron spectroscopy (XPS). The XPS spectrum reflects the constituent elements and chemical bond state of only the surface layer of the sample (typically about a few nm). Peak separation is performed on the obtained C1s spectrum, and the DSs can be calculated by the following formula based on the area intensity (Ixf) of the peak assigned to one carbon atom derived from the modifying group relative to the area intensity (Ixp) of the peak (289 eV, CC bond) assigned to carbons C2-C6 derived from the pyranose ring of cellulose. DSs = (Ixf) x 5 / (Ixp) For example, if the modifying group is an acetyl group, after peak separation of the C1s spectrum at 285 eV, 286 eV, 288 eV, and 289 eV, the peak at 289 eV can be used for Ixp and the peak derived from the O-C=O bond of the acetyl group (286 eV) can be used for Ixf. The conditions for the XPS measurement are as follows, for example: Equipment used: ULVAC-Phi VersaProbe II Excitation source: mono.AlKα 15kV×3.33mA Analysis size: Approx. 200 μm φ Photoelectron extraction angle: 45° Capture Area Narrow scan: C 1s, O 1s Pass Energy: 23.5eV

[0082] <Resin> The resin contained in the resin composition of the present disclosure may be a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like. In a typical embodiment, the resin is a thermoplastic resin. The thermoplastic resin may be, for example, a crystalline resin having a melting point in the range of 100°C to 350°C, an amorphous resin having a glass transition temperature in the range of 100°C to 250°C, or the like. In the present disclosure, the melting point refers to the peak top temperature of an endothermic peak that appears when the temperature is increased from 23°C at a heating rate of 10°C / min using a differential scanning calorimeter (DSC), and when two or more endothermic peaks appear, it refers to 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, more preferably 20 J / g or more. In addition, when measuring, it is desirable to use a sample that is once heated to a temperature condition of melting point + 20°C or more to melt the resin, and then cooled to 23°C at a heating rate of 10°C / min. In the present disclosure, the glass transition temperature refers to the peak top temperature at which the storage modulus is greatly reduced and the loss modulus is maximized when measured using a dynamic viscoelasticity measuring device at a heating rate of 2°C / min from 23°C and an applied frequency of 10Hz. When two or more loss modulus peaks appear, the glass transition temperature refers to the peak top temperature of the peak on the highest temperature side. In this case, the measurement frequency is preferably at least once every 30 seconds to improve measurement accuracy. In addition, there is no particular restriction on the method of preparing the measurement sample, but from the viewpoint of eliminating the influence of molding distortion, it is preferable to use a cut piece of a heat press molded product, and it is preferable from the viewpoint of heat conduction that the size (width and thickness) of the cut piece is as small as possible.

[0083] Examples of thermoplastic resins include polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyphenylene ether resins, polyphenylene sulfide resins, and mixtures of two or more of these. From the viewpoint of handling and cost, preferred are polyolefin resins, polyamide resins, polyester resins, polyacetal resins, etc., more preferred are polyamide resins, polyolefin resins, and polyacetal resins, and particularly preferred are polyamide resins and polyacetal resins. The melting point of the thermoplastic resin (particularly the crystalline resin) is preferably 140°C or higher, or 150°C or higher, or 160°C or higher, or 170°C or higher, or 180°C or higher, or 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, from the viewpoint of increasing the heat resistance of the resin composition.

[0084] The melting point of the thermoplastic resin can be, for example, 150°C to 190°C or 160°C to 180°C for a resin with a relatively low melting point (such as a polyolefin-based resin), and 220°C to 350°C or 230°C to 320°C for a resin with a relatively high melting point (such as a polyamide-based resin).

[0085] The thermoplastic resin may preferably be at least one selected from the group consisting of polyolefin-based resins, polyacetate-based resins, polycarbonate-based resins, polyamide-based resins, polyester-based resins, polyphenylene ether-based resins, and acrylic-based resins.

[0086] The polyolefin resin preferred as the thermoplastic resin is a polymer obtained by polymerizing olefins (e.g., α-olefins) and / or alkenes as monomer units.Specific examples of the polyolefin resin include ethylene (co)polymers such as low-density polyethylene (e.g., linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, and ultra-high-molecular-weight polyethylene, polypropylene (co)polymers such as polypropylene, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer, and copolymers of ethylene and α-olefins such as ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-glycidyl methacrylate copolymer.

[0087] Here, the most preferred polyolefin resin is polypropylene. In particular, polypropylene having a melt mass flow rate (MFR) of 3 g / 10 min or more and 30 g / 10 min or less, measured at 230 ° C. and a load of 21.2 N according to ISO1133, is preferred. 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 min, even more preferably 20 g / 10 min, and most preferably 18 g / 10 min. From the viewpoint of improving the toughness of the resin composition, it is desirable that MFR does not exceed the above upper limit, and from the viewpoint of the flowability of the resin composition, it is desirable that MFR does not exceed the above lower limit.

[0088] In addition, in order to increase the affinity with cellulose nanofibers, an acid-modified polyolefin resin can also be suitably used. As the acid used for the acid modification, a mono- or polycarboxylic acid can be used, and examples thereof include maleic acid, fumaric acid, succinic acid, phthalic acid and their anhydrides, and citric acid. Maleic acid or its anhydride is particularly preferred because it is easy to increase the modification rate. There is no particular restriction on the modification method, but a method in which a polyolefin resin is heated to a melting point or higher in the presence or absence of a peroxide and melt-kneaded is common. As the polyolefin resin to be acid-modified, all of the above-mentioned polyolefin resins can be used, but polypropylene is particularly suitable. The acid-modified polypropylene resin may be used alone, but it is more preferable to use it in combination with an unmodified polypropylene resin in order to adjust the modification rate of the resin as a whole. In this case, the ratio of the acid-modified polypropylene resin to all polypropylene resins is preferably 0.5% by mass to 50% by mass. A more preferred lower limit is 1 mass%, or 2 mass%, or 3 mass%, or 4 mass%, or 5 mass%. A more preferred upper limit is 45 mass%, or 40 mass%, or 35 mass%, or 30 mass%, or 20 mass%. In order to maintain the interfacial strength between the resin and the cellulose nanofiber, a content equal to or greater than the lower limit is preferred, and in order to maintain the ductility of the resin, a content equal to or less than the upper limit is preferred.

[0089] The melt mass flow rate (MFR) of the acid-modified polypropylene resin measured in accordance with ISO 1133 at 230°C under a load of 21.2 N is preferably 50 g / 10 min or more, 100 g / 10 min or more, 150 g / 10 min or more, or 200 g / 10 min or more from the viewpoint of increasing the affinity at the interface between the resin and the cellulose nanofiber. There is no particular upper limit, but it is preferably 500 g / 10 min from the viewpoint of maintaining mechanical strength.

[0090] Examples of polyamide-based resins that are preferable as the thermoplastic resin include polyamides obtained by polycondensation reaction of lactams (e.g., polyamide 6, polyamide 11, polyamide 12, etc.); diamines (e.g., 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 1,7-heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylenediamine, etc.) and dicarboxylic acids (e.g., 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, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, etc.) (for example, polyamide 6,6, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6,T, polyamide 6,I, polyamide 9,T, polyamide 10,T, polyamide 2M5,T, polyamide MXD,6, polyamide 6,C, polyamide 2M5,C, etc.); and copolymers in which these are copolymerized (for example, polyamide 6,T / 6,I, etc.).

[0091] Among these polyamide resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6,10, polyamide 6,11, and polyamide 6,12, and alicyclic polyamides such as polyamide 6,C and polyamide 2M5,C are more preferred.

[0092] From the viewpoint of improving the heat resistance of the resin composition, the melting point of the polyamide resin is preferably 220°C or more, or 230°C or more, or 240°C or more, or 245°C or more, or 250°C or more, and from the viewpoint of ease of production of the resin composition, the melting point is preferably 350°C or less, or 320°C or less, or 300°C or less.

[0093] The terminal carboxyl group concentration of the polyamide resin is not particularly limited, but is preferably 20 μmol / g or more, or 30 μmol / g or more, and preferably 150 μmol / g or less, or 100 μmol / g or less, or 80 μmol / g or less.

[0094] In the polyamide-based resin, the ratio of carboxyl end groups to all end groups ([COOH] / [total end groups]) is preferably 0.30 or more, or 0.35 or more, or 0.40 or more, or 0.45 or more from the viewpoint of dispersibility of the cellulose nanofibers in the resin composition, and is preferably 0.95 or less, or 0.90 or less, or 0.85 or less, or 0.80 or less from the viewpoint of the color tone of the resin composition.

[0095] The terminal group concentration of the polyamide resin can be adjusted by a known method, such as adding a terminal regulator (e.g., 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.) that reacts with the terminal group during polymerization of the polyamide to the polymerization liquid so as to obtain a predetermined terminal group concentration.

[0096] Examples of the terminal regulator that reacts with the terminal amino group include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; 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; and mixtures of a plurality of terminal regulators selected from the above. Among these, from the viewpoints of reactivity, stability of the blocked terminal, and cost, one or more terminal regulators selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferred, and acetic acid is most preferred.

[0097] Examples of the terminal regulator that reacts with the terminal carboxyl group include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, etc., alicyclic monoamines such as cyclohexylamine, dicyclohexylamine, etc., aromatic monoamines such as aniline, toluidine, diphenylamine, naphthylamine, etc., and any mixtures thereof. Among these, one or more terminal regulators selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferred in terms of reactivity, boiling point, stability of the blocked terminal, price, etc.

[0098] The concentration of amino end groups and carboxyl end groups of the polyamide resin is 1 It can be determined from the integral value of the characteristic signal corresponding to each terminal group by H-NMR. This method is preferable in terms of accuracy and simplicity. More specifically, it is recommended to use the method described in JP-A-7-228775, use deuterated trifluoroacetic acid as the measurement solvent, and set the number of integration scans to 300 or more.

[0099] The intrinsic viscosity [η] of the polyamide resin measured under the condition of 30°C in concentrated sulfuric acid is preferably 0.6 to 2.0 dL / g, or 0.7 to 1.4 dL / g, or 0.7 to 1.2 dL / g, or 0.7 to 1.0 dL / g, from the viewpoint that the fluidity in the mold is good and the appearance of the molded piece is good when the resin composition is injection molded. In the present disclosure, the "intrinsic viscosity" is synonymous with the viscosity generally called the limiting viscosity. The intrinsic viscosity is obtained by measuring the ηsp / c of ​​several measurement solvents having different concentrations under the temperature condition of 30°C in 96% concentrated sulfuric acid, deriving the relational equation between each of the ηsp / c and the concentration (c), and extrapolating the concentration to zero. The value extrapolated to zero is the intrinsic viscosity. Details of the above method are described, for example, in Polymer Process Engineering (Prentice-Hall, Inc. 1994), pages 291 to 294, etc. From the viewpoint of accuracy, it is desirable to set the concentrations in the measurement solvents having different concentrations to at least four points (for example, 0.05 g / dL, 0.1 g / dL, 0.2 g / dL, and 0.4 g / dL).

[0100] As the polyester resin preferred as the thermoplastic resin, one or more selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoic acid (PHA), polylactic acid (PLA), polyarylate (PAR), etc. can be used. Among them, PET, PBS, PBSA, PBT and PEN are more preferred, and PBS, PBSA and PBT are particularly preferred.

[0101] The terminal groups of the polyester resin can be changed as desired by the monomer ratio during polymerization, the presence or absence and amount of addition of a terminal stabilizer, etc. The ratio of carboxyl terminal groups to all terminal groups of the polyester resin ([COOH] / [total terminal groups]) is preferably 0.30 or more, or 0.35 or more, or 0.40 or more, or 0.45 or more from the viewpoint of dispersibility of cellulose nanofibers in the resin composition, and is preferably 0.95 or less, or 0.90 or less, or 0.85 or less, or 0.80 or less from the viewpoint of the color tone of the resin composition.

[0102] As the polyacetal resin preferred as the thermoplastic resin, homopolyacetal made from formaldehyde and copolyacetal containing trioxane as the main monomer and 1,3-dioxolane as the comonomer component are generally used, and although both can be used, copolyacetal is preferred from the viewpoint of thermal stability during processing. The amount of the structure derived from the comonomer component (e.g., 1,3-dioxolane) is preferably 0.01 mol% or more, or 0.05 mol% or more, or 0.1 mol% or more, or 0.2 mol% or more from the viewpoint of thermal stability during extrusion processing and molding processing, and is preferably 4.0 mol% or less, or 3.5 mol% or less, or 3.0 mol% or less, or 2.5 mol% or less, or 2.3 mol% or less from the viewpoint of mechanical strength.

[0103] <Liquid polymer> The liquid polymer contained in the resin composition of the present disclosure means a polymer having fluidity at 23°C. In one embodiment, the liquid polymer has a glass transition temperature (Tg). In one embodiment, the liquid polymer may be a conjugated diene-based polymer or a non-conjugated diene-based polymer. In one embodiment, the liquid polymer is liquid rubber. In the present disclosure, the liquid rubber means a substance having fluidity at 23°C and forming a rubber elastomer by crosslinking (more specifically, vulcanization) and / or chain extension. That is, the liquid rubber is an uncured material in one embodiment.

[0104] In one embodiment, having fluidity means that when a liquid polymer dissolved in cyclohexane is placed in a vial having a body diameter of 21 mm and a total length of 50 mm at 23°C and then dried, the liquid polymer is filled into the vial to a height of 1 mm and sealed, and the vial is left to stand upside down for 24 hours, and a movement of the material in the vertical direction of 0.1 mm or more can be confirmed.

[0105] The liquid polymer may have a monomer composition of a general polymer, and preferably has a relatively low molecular weight from the viewpoint of ease of handling and good dispersibility of cellulose nanofibers. In one embodiment, the liquid polymer has a number average molecular weight (Mn) of 80,000 or less, and thus has a liquid form. The number average molecular weight and weight average molecular weight of various polymers in the present disclosure are values ​​determined in terms of standard polystyrene using gel permeation chromatography, using chloroform as a solvent, and at a measurement temperature of 40°C, unless otherwise specified.

[0106] In one embodiment, a liquid polymer may be combined with cellulose nanofibers to form a masterbatch, and such masterbatch may be combined with a resin to form the resin composition of the present disclosure.

[0107] The number average molecular weight (Mn) of the liquid polymer is preferably 1,000 or more, or 1,500 or more, or 2,000 or more from the viewpoint of thermal stability and the effect of improving the dispersibility of cellulose nanofibers in the resin, and is preferably 80,000 or less, or 50,000 or less, or 40,000 or less, or 30,000 or less, or 10,000 or less in terms of having high fluidity suitable for good dispersion when dispersing cellulose nanofibers in the liquid polymer.

[0108] The weight average molecular weight (Mw) of the liquid polymer is preferably 1,000 or more, or 2,000 or more, or 4,000 or more from the viewpoint of thermal stability and the effect of improving the dispersibility of cellulose nanofibers in the resin, and is preferably 240,000 or less, or 150,000 or less, or 30,000 or less in terms of having high fluidity suitable for good dispersion when dispersing cellulose nanofibers in the liquid polymer.

[0109] The ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of the liquid polymer is preferably 1.5 or more, or 1.8 or more, or 2 or more, in that a certain degree of variation in molecular weight makes it possible to achieve a high degree of compatibility between multiple properties (in one embodiment, a high degree of compatibility between good dispersion of cellulose nanofibers in the resin and good flexural modulus of the resin composition), and is preferably 10 or less, or 8 or less, or 5 or less, or 3 or less, or 2.7 or less, in that the variation in molecular weight is not excessively large and the desired physical properties of the resin composition can be stably obtained, for example, in that it is possible to achieve both fluidity and impact resistance.

[0110] The liquid polymer can have good thermal stability. The thermal decomposition onset temperature (T D In terms of good thermal stability, in one embodiment, the thermal decomposition onset temperature is more than 200° C., or 210° C. or higher, or 230° C. or higher, or 250° C. or higher, or 300° C. or higher. Although a higher thermal decomposition onset temperature is preferable, in terms of availability of the liquid polymer, in one embodiment, the thermal decomposition onset temperature may be 500° C. or lower, or 450° C. or lower, or 400° C. or lower.

[0111] The glass transition temperature of the liquid polymer is preferably -150°C or higher, or -120°C or higher, or -100°C or higher in terms of good thermal stability, and is preferably 25°C or lower, or 10°C or lower, or 0°C or lower in terms of good fluidity.

[0112] In one embodiment, the liquid polymer includes a diene polymer, and in another embodiment, the liquid polymer includes a conjugated diene polymer or a non-conjugated diene polymer, or a hydrogenated product thereof. The above polymer or the hydrogenated product thereof may be an oligomer. The monomer constituting the liquid polymer may be unmodified or modified (e.g., acid modified, hydroxyl group modified, etc.). In one embodiment, the liquid polymer may have reactive groups (e.g., one or more selected from the group consisting of hydroxyl groups, carboxy groups, isocyanato groups, thio groups, amino groups, and halo groups) at both ends, and therefore may be bifunctional. These reactive groups contribute to crosslinking and / or chain extension of the liquid polymer.

[0113] [Conjugated diene polymer] The conjugated diene polymer may be a homopolymer, a copolymer of two or more conjugated diene monomers, or a copolymer of a conjugated diene monomer and another monomer. The copolymer may be either random or block.

[0114] Conjugated diene monomers include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene, which may be used alone or in combination of two or more.

[0115] In one embodiment, the conjugated diene polymer is a copolymer of the above-mentioned conjugated diene monomer and an aromatic vinyl monomer. The aromatic vinyl monomer is not particularly limited as long as it is a monomer copolymerizable with the conjugated diene monomer, and examples thereof include styrene, m- or p-methylstyrene, α-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, diphenylethylene, and divinylbenzene, and these may be used alone or in combination of two or more. From the viewpoint of the molding processability of the resin composition and the impact resistance of the molded product, styrene is preferred.

[0116] Examples of random copolymers include butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and butadiene-isoprene-styrene random copolymers. The composition distribution of each monomer in the copolymer chain includes a completely random copolymer that is close to a statistically random composition, and a tapered (gradient) random copolymer that has a gradient in composition distribution. The bond type of the conjugated diene polymer, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or different between molecules.

[0117] The block copolymer may be a copolymer consisting of two or more blocks. For example, the block copolymer may be a block copolymer in which a block A of an aromatic vinyl monomer and a block B of a conjugated diene monomer and / or a copolymer of an aromatic vinyl monomer and a conjugated diene monomer constitute a structure such as AB, ABA, or ABAB. The boundaries of the blocks do not necessarily need to be clearly distinguished. For example, when the block B is a copolymer of an aromatic vinyl monomer and a conjugated diene monomer, the aromatic vinyl monomer in the block B may be distributed uniformly or in a tapered shape. In addition, the block B may have a plurality of parts in which the aromatic vinyl monomer is distributed uniformly and / or a plurality of parts in which the aromatic vinyl monomer is distributed in a tapered shape. Furthermore, the block B may have a plurality of segments with different aromatic vinyl monomer contents. When the copolymer has a plurality of blocks A and B, the molecular weights and compositions of the blocks A and B may be the same or different.

[0118] The block copolymer may be a mixture of two or more types differing from each other in one or more of the bond type, molecular weight, aromatic vinyl compound type, conjugated diene compound type, 1,2-vinyl content or the total amount of 1,2-vinyl content and 3,4-vinyl content, aromatic vinyl compound component content, hydrogenation rate, etc.

[0119] The amount of vinyl bonds (for example, 1,2- or 3,4-bonds of butadiene) in the conjugated diene bond units in the conjugated diene polymer is preferably 10 mol % or more and 75 mol % or less, or 13 mol % or more and 65 mol % or less. The amount of vinyl bonds in the conjugated diene bond units (for example, the amount of 1,2-bonds in butadiene) is 13 It can be determined by C-NMR (quantitative mode). 13 By integrating the peak areas appearing in the following C-NMR, a value proportional to the carbon amount of each structural unit can be obtained, which can then be converted into mass % of each structural unit. Styrene 145~147ppm Vinyl 110~116ppm Diene(cis) 24~28ppm Diene (trans) 29~33ppm

[0120] In the copolymer of a conjugated diene monomer and an aromatic vinyl monomer, the amount of the aromatic vinyl monomer bonded to the conjugated diene monomer (also referred to as the aromatic vinyl bond amount in the present disclosure) may be preferably 5 mol % or more and 70 mol % or less, or 10 mol % or more and 50 mol % or less, relative to 100% of the total moles of the conjugated diene polymer.

[0121] The hydrogenated product of the conjugated diene polymer may be the hydrogenated products of the conjugated diene polymers exemplified above, for example, a hydrogenated product of a butadiene homopolymer, an isoprene homopolymer, a styrene-butadiene copolymer, or an acrylonitrile-butadiene copolymer.

[0122] In a preferred embodiment, the liquid polymer is one or more selected from the group consisting of polybutadiene, butadiene-styrene copolymer, polyisoprene, and polychloroprene, which may be derivatives (e.g., maleic anhydride modified products, methacrylic acid modified products, terminal hydroxyl group modified products, hydrogenated products, and combinations thereof).

[0123] [Non-conjugated diene polymer] The non-conjugated diene polymer may be a homopolymer, a copolymer of two or more kinds of non-conjugated diene monomers, or a copolymer of a non-conjugated diene monomer and another monomer. The copolymer may be either random or block. Examples of the non-conjugated diene polymer include olefin polymers (e.g., liquid paraffin), silicone polymers, and acrylic polymers. For example, examples of the non-conjugated diene polymer when the liquid polymer is liquid rubber include: Olefin polymers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, and ethylene-α-olefin copolymers; Examples of the rubber include butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0124] In the ethylene-α-olefin copolymer, examples of monomers that can be copolymerized with the ethylene unit include aliphatic substituted vinyl monomers such as propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, or eicosene-1, and isobutylene, and styrene. aromatic vinyl monomers such as substituted styrenes and substituted styrenes; ester vinyl monomers such as vinyl acetate, acrylic esters, methacrylic esters, glycidyl acrylic esters, glycidyl methacrylic esters, and hydroxyethyl methacrylic esters; nitrogen-containing vinyl monomers such as acrylamide, allylamine, vinyl-p-aminobenzene, and acrylonitrile; and dienes such as butadiene, cyclopentadiene, 1,4-hexadiene, and isoprene.

[0125] The ethylene-α-olefin copolymer is preferably a copolymer of ethylene and one or more α-olefins having 3 to 20 carbon atoms, more preferably a copolymer of ethylene and one or more α-olefins having 3 to 16 carbon atoms, and most preferably a copolymer of ethylene and one or more α-olefins having 3 to 12 carbon atoms.

[0126] From the viewpoint of impact resistance, the molecular weight of the ethylene-α-olefin copolymer is preferably 10,000 or more, more preferably 10,000 to 100,000, more preferably 10,000 to 80,000, and even more preferably 20,000 to 60,000, as a number average molecular weight (Mn) measured using a gel permeation chromatography measuring device with 1,2,4-trichlorobenzene as a solvent at 140°C and polystyrene standard.

[0127] From the viewpoint of handling during processing, the ethylene unit content of the ethylene-α-olefin copolymer is preferably 30 to 95% by mass based on the total amount of the ethylene-α-olefin copolymer.

[0128] The ethylene-α-olefin copolymer can be produced by a conventionally known production method such as those described in JP-B-4-12283, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, JP-A-5-155930, JP-A-3-163088, and U.S. Pat. No. 5,272,236.

[0129] In one embodiment, the liquid polymer comprises at least one selected from the group consisting of diene rubber, silicone rubber, urethane rubber, and polysulfide rubber, and hydrogenated products thereof.

[0130] The viscosity of the liquid polymer at 25°C is preferably 1,000,000 mPa·s or less, or 500,000 mPa·s or less, or 200,000 mPa·s or less, from the viewpoint of good dispersion of the cellulose nanofibers in the liquid polymer, and is preferably 100 mPa·s or more, or 300 mPa·s or more, or 500 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose nanofibers in the resin, and the mechanical properties of the resin composition.

[0131] The viscosity of the liquid polymer at 50°C is preferably 1,000,000 mPa·s or less, or 500,000 mPa·s or less, or 200,000 mPa·s or less, or 100,000 mPa·s or less, from the viewpoints of well dispersing the cellulose nanofibers in the liquid polymer and well dispersing the cellulose nanofibers in the resin by heating and kneading, and is preferably 50 mPa·s or more, or 100 mPa·s or more, or 500 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose nanofibers in the resin, and the mechanical properties of the resin composition.

[0132] The viscosity of the liquid polymer at 80°C is preferably 1,000,000 mPa·s or less, or 500,000 mPa·s or less, or 250,000 mPa·s or less, or 100,000 mPa·s or less, from the viewpoints of well dispersing the cellulose nanofibers in the liquid polymer and well dispersing the cellulose nanofibers in the resin by heating and kneading, and is preferably 50 mPa·s or more, or 100 mPa·s or more, or 300 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose nanofibers in the resin, and the mechanical properties of the resin composition.

[0133] The viscosity of the liquid polymer at 0°C is preferably 2,000,000 mPa·s or less, or 1,000,000 mPa·s or less, or 400,000 mPa·s or less, from the viewpoint of good dispersion of the cellulose nanofibers in the liquid polymer, and is preferably 200 mPa·s or more, or 600 mPa·s or more, or 1,000 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose nanofibers in the resin, and the mechanical properties of the resin composition.

[0134] It is preferable that the viscosities of the liquid polymer at 80°C, 50°C, 25°C and 0°C are all within the above ranges, as this allows the cellulose nanofibers to be well dispersed in the liquid polymer over a wide range of mixing temperatures.

[0135] The viscosity of the liquid polymer is a value measured using a Brookfield viscometer at a rotation speed of 10 rpm.

[0136] The ratio η50 / ηTm of the viscosity η50 of the liquid polymer at 50°C to the viscosity ηTm of the liquid polymer at "the melting point of the thermoplastic resin + 20°C" is preferably 20 or more, or 30 or more, or 50 or more, or 80 or more, or 100 or more, or 150 or more, from the viewpoint of adequately coating the cellulose nanofibers with the liquid polymer, and is preferably 10,000 or less, or 5,000 or less, from the viewpoint of facilitating material design according to the desired viscosity.

[0137] The ratio ηr / ηTm of the viscosity ηTm of the liquid polymer at "melting point of thermoplastic resin + 20°C" to the melt viscosity ηr of the thermoplastic resin at "melting point of thermoplastic resin + 20°C" is preferably 100,000 or less, or 75,000 or less, or 50,000 or less, or 25,000 or less, from the viewpoint of good dispersion of cellulose nanofibers in the molten resin, and is preferably 100 or more, from the viewpoint of facilitating material design according to the desired viscosity.

[0138] In a preferred embodiment, the viscosity η50 of the liquid polymer at 50° C., the viscosity ηTm of the liquid polymer at a temperature 20° C. above the melting point of the thermoplastic resin, and the melt viscosity ηr of the thermoplastic resin at a temperature 20° C. above the melting point of the thermoplastic resin satisfy the following relationship: η50 / ηTm≧20 1≦ηr / η50≦1000 satisfies. Controlling the viscosity of the liquid polymer is advantageous in terms of obtaining a favorable effect of improving dispersibility by having the liquid polymer be present around the cellulose nanofibers. The η50 / ηTm ratio is an index of the change in viscosity when the liquid polymer is heated during melt mixing of the cellulose nanofibers, resin, and liquid polymer. The ηr / η50 ratio is an index of how fluid the liquid polymer is in terms of the balance with the resin during the melt mixing. When both the η50 / ηTm ratio and the ηr / η50 ratio satisfy the above relationship, the liquid polymer has good fluidity during melt mixing without being excessively viscous, and can therefore remain around the cellulose nanofibers and exhibit a favorable effect of improving the dispersion of the cellulose nanofibers in the resin.

[0139] The ηr / η50 ratio is preferably 1 or more, or 2 or more, or 3 or more, in order to prevent the liquid polymer from penetrating into the surface of the cellulose nanofibers and suppressing aggregation when the cellulose nanofibers are dried, and is preferably 1,000 or less, or 500 or less, or 300 or less, in order to prevent the liquid polymer from becoming excessively high in fluidity and to allow the liquid polymer to remain well around the cellulose nanofibers.

[0140] The more suitable ranges of each of the η50 / ηTm ratio, the ηr / η50 ratio, and the ηr / ηTm ratio may vary depending on the type of thermoplastic resin. For example, it is advantageous to make the η50 / ηTm ratio relatively small for a thermoplastic resin having a relatively low melting point and relatively large for a thermoplastic resin having a relatively high melting point, in terms of facilitating material design according to the desired viscosity. In addition, in the case of a resin having a high melting point such as a polyamide resin, it is advantageous to set the ηr / η50 ratio to a relatively large value in terms of facilitating material design according to a desired viscosity. Furthermore, the ηr / ηTm ratio can be made relatively large in a resin having extremely high crystallinity and high melt viscosity, such as a polyacetal resin.

[0141] In one embodiment, the thermoplastic resin is a polyolefin resin, and η50 and ηTm at the melting point of the polyolefin resin + 20°C have the following relationship: η50 / ηTm≧20 The η50 / ηTm ratio in the polyolefin resin is preferably 20 or more, or 30 or more, or 100 or more from the above-mentioned viewpoint, and is preferably 1000 or less, or 500 or less, or 300 or less from the above-mentioned viewpoint.

[0142] When the thermoplastic resin is a polyolefin resin, ηr at the melting point of the polyolefin resin + 20°C and ηTm at the melting point of the polyolefin resin + 20°C preferably satisfy the following relationship: ηr / ηTm≦50000 The ηr / ηTm ratio in the polyolefin resin is preferably 50,000 or less, or 30,000 or less, or 20,000 or less from the above-mentioned viewpoint, and is preferably 100 or more from the above-mentioned viewpoint.

[0143] In one embodiment, the thermoplastic resin is a polyacetal resin, and η50 and ηTm at the melting point of the polyacetal resin + 20°C have the following relationship: η50 / ηTm≧20 The η50 / ηTm ratio in the polyacetal resin is preferably 20 or more, or 30 or more, or 45 or more, or 100 or more from the above-mentioned viewpoint, and is preferably 2000 or less, or 1500 or less, or 1000 or less from the above-mentioned viewpoint.

[0144] When the thermoplastic resin is a polyacetal resin, ηr at the melting point of the polyacetal resin + 20°C and ηTm at the melting point of the polyacetal resin + 20°C have the following relationship: ηr / ηTm≦100000 The ηTm / ηr ratio in the polyacetal resin is preferably 100,000 or less, or 50,000 or less, or 40,000 or less, from the above-mentioned viewpoint, and is preferably 100 or more, from the above-mentioned viewpoint.

[0145] In one embodiment, the thermoplastic resin is a polyamide resin, and η50 and ηTm at a melting point of the polyamide resin + 20°C have the following relationship: η50 / ηTm≧80 The η50 / ηTm ratio in the polyamide resin is preferably 80 or more, or 100 or more, or 150 or more, or 500 or more, from the above-mentioned viewpoint, and is preferably 10,000 or less, or 5,000 or less, or 1,000 or less, from the above-mentioned viewpoint.

[0146] When the thermoplastic resin is a polyamide resin, ηr at the melting point of the polyamide resin + 20°C and ηTm at the melting point of the polyamide resin + 20°C have the following relationship: ηr / ηTm≦50000 The ηTm / ηr ratio in the polyamide resin is preferably 50,000 or less, or 40,000 or less, or 30,000 or less, from the above-mentioned viewpoint, and is preferably 100 or more, from the above-mentioned viewpoint.

[0147] <Dispersion aid> In one aspect, the resin composition of the present embodiment does not contain a surfactant. Liquid polymers tend to have better thermal stability than non-polymer surfactants, and are therefore advantageous in that even if the resin composition is heated during production and processing, the mechanical properties, decorativeness, and appearance of the resin composition and the molded product are not adversely affected. The resin composition according to one aspect may be surfactant-free because the liquid polymer contributes to good dispersion of the cellulose nanofibers even without the surfactant. In this disclosure, surfactant-free means that the amount of surfactant in the resin composition is less than 0.1 parts by mass relative to 100 parts by mass of the liquid polymer. On the other hand, in one aspect, a small amount of a dispersion aid may be contained in order to modify the surface of the cellulose nanofibers through interaction and further improve the dispersion of the cellulose nanofibers by the liquid polymer. From the viewpoint of improving the dispersibility of cellulose nanofibers, the dispersing aid may be contained in an amount of preferably 0.1 part by mass or more, or 1 part by mass or more, or 5 parts by mass or more, per 100 parts by mass of the liquid polymer, and from the viewpoint of performance degradation due to the dispersing aid, the dispersing aid may be contained in an amount of preferably 50 parts by mass or less, or 30 parts by mass or less, or 10 parts by mass or less.

[0148] In one embodiment, the dispersing aid preferably has a hydrophilic segment and a hydrophobic segment in the same molecule (i.e., is an amphiphilic molecule) from the viewpoint of dispersing the fine cellulose fibers more uniformly in the resin.

[0149] The hydrophilic segment is a portion that exhibits good affinity with fine cellulose fibers by containing a hydrophilic structure. Examples of the hydrophilic structure include hydroxyl groups, thiol groups, carboxyl groups, sulfonic acid groups, sulfate ester groups, phosphate groups, boronic acid groups, silanol groups, groups derived from sugars such as sorbitan and sucrose, groups derived from glycerin, -OM, -COOM, -SO 3 M, -OSO 3 M, -HMPO 4 , and -M 2 PO 4(wherein M represents an alkali metal or an alkaline earth metal), as well as primary to tertiary amines and quaternary ammonium salts, etc. Examples of the counter anion of the quaternary ammonium salt include halide ions such as hydroxide ions, fluoride ions, chloride ions, bromide ions, and iodide ions, as well as one or more hydrophilic groups selected from the group consisting of nitrate ions, formate ions, acetate ions, trifluoroacetate ions, p-toluenesulfonate ions, hexafluorophosphate, and tetrafluoroborate, etc.

[0150] Examples of hydrophilic segments include segments containing a repeating unit having a quaternary ammonium salt structure, polyvinyl alcohol segments, polyvinylpyrrolidone segments, polyacrylic acid segments, carboxyvinyl polymer segments, cationized guar gum segments, hydroxyethyl cellulose segments, methyl cellulose segments, carboxymethyl cellulose segments, polyurethane soft segments (specifically diol segments), and the like.

[0151] Examples of hydrophobic segments include segments having a hydrocarbon and segments containing a polymer structure: Preferred examples of the segment having a hydrocarbon include alkyl, alkenyl, alkyl ether, alkenyl ether, alkyl phenyl ether, alkenyl phenyl ether, rosin ester, bisphenol A, β-naphthyl, styrenated phenyl, and hardened castor oil. The number of carbon atoms in the alkyl or alkenyl chain of the hydrophobic group (the number of carbon atoms excluding the phenyl group in the case of alkylphenyl or alkenylphenyl) is preferably 5 or more, or 10 or more, or 12 or more, or 16 or more. Examples of the segment containing a polymer structure include acrylic polymers, styrene resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, polyhexamethylene adipamide (6,6 nylon), polyhexamethylene azelamide (6,9 nylon), polyhexamethylene sebacamide (6,10 nylon), polyhexamethylene dodecanoamide (6,12 nylon), polybis(4-aminocyclohexyl)methandodecane, and other polycondensates of organic dicarboxylic acids having 4 to 12 carbon atoms and organic diamines having 2 to 13 carbon atoms, and polycondensates of ω-amino acids (e.g., ω-aminoundecanoic acid) (e.g., polyundecane). Preferred are amino acid lactams including ring-opening polymerization products of lactams such as polycapramide (nylon 11), which is a ring-opening polymerization product of ε-aminocaprolactam, polycapramide (nylon 6), which is a ring-opening polymerization product of ε-aminolaurolactam, and polylauric lactam (nylon 12), which is a ring-opening polymerization product of ε-aminolaurolactam; polymers composed of diamines and dicarboxylic acids; polyacetal resins, polycarbonate resins, polyester resins, polyphenylene sulfide resins, polysulfone resins, polyether ketone resins, polyimide resins, fluorine resins, hydrophobic silicone resins, melamine resins, epoxy resins, and phenolic resins.

[0152] In one embodiment, the amphiphilic molecule may be any of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. The dispersion aid may be a polymeric surfactant, a reactive surfactant, etc. In terms of affinity with fine cellulose fibers, cationic surfactants and nonionic ionic surfactants are preferred, and in terms of heat resistance, nonionic surfactants are more preferred.

[0153] In terms of affinity with cellulose nanofibers, the hydrophilic groups of surfactants include groups derived from sugars such as sorbitan and sucrose, groups derived from glycerin, hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphate groups, -OM, -COOM, -SO 3 M, -OSO 3 M, -HMPO 4 , and -M 2 PO 4(wherein M represents an alkali metal or an alkaline earth metal), as well as primary to tertiary amines and quaternary ammonium salts. The counter anion of the quaternary ammonium salt is preferably one or more ions selected from the group consisting of halide ions such as hydroxide ions, fluoride ions, chloride ions, bromide ions, and iodide ions, as well as nitrate ions, formate ions, acetate ions, trifluoroacetate ions, p-toluenesulfonate ions, hexafluorophosphate ions, and tetrafluoroborate ions.

[0154] As the structure of the hydrophobic group of the surfactant, alkyl type, alkenyl type, alkyl ether type, alkenyl ether type, alkyl phenyl ether type, alkenyl phenyl ether type, rosin ester type, bisphenol A type, β naphthyl type, styrenated phenyl type, and hardened castor oil type are preferred in terms of high affinity with the resin. The number of carbon atoms of the alkyl chain or alkenyl chain of the hydrophobic group (the number of carbon atoms excluding the phenyl group in the case of alkyl phenyl or alkenyl phenyl) is preferably 5 or more, or 10 or more, or 12 or more, or 16 or more. For example, when the resin is a polyolefin resin, the more carbon atoms of the surfactant, the higher the affinity with the resin. The number of carbon atoms may be, for example, 30 or less, or 25 or less.

[0155] As the hydrophobic group, those having a cyclic structure or those having a bulky and multifunctional structure are more preferred. As the hydrophobic group having a cyclic structure, alkylphenyl ether type, alkenylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, and styrenated phenyl type groups are preferred, and as those having a multifunctional structure, hydrogenated castor oil type (e.g. hydrogenated castor oil ether) groups are preferred. Rosin ester type and hydrogenated castor oil type are particularly preferred.

[0156] More specific examples of the surfactant include fatty acid esters (for example, sorbitan fatty acid esters, glycerin fatty acid esters, sucrose fatty acid esters, propylene glycol fatty acid esters, etc.).

[0157] Examples of dispersion aids other than surfactants include long-chain fatty acids such as palmitoleic acid, oleic acid, eicosenoic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, and arachidic acid, and long-chain amines such as palmitoylamine, oleylamine, eicosylamine, myristylamine, pentadecylamine, palmitylamine, margarylamine, stearylamine, and arachidylamine. The term "long chain" as used above means a chain length having 13 or more carbon atoms, and in one embodiment may be 13 to 21 carbon atoms.

[0158] <Additional Ingredients> The resin composition may further contain additional components as necessary to improve its performance. Examples of the additional components include filler components other than cellulose nanofibers; compatibilizers; plasticizers; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as zeolite, ceramics, talc, silica, metal oxides, and metal powders; colorants; fragrances; pigments; flow regulators; leveling agents; conductive agents; heat stabilizers; antioxidants; antistatic agents; ultraviolet absorbers; ultraviolet dispersants; and deodorants. The content ratio of any additional component in the resin composition is appropriately selected within a range that does not impair the desired effects of the present invention, and may be, for example, 0.01 to 50% by mass, or 0.1 to 30% by mass.

[0159] The liquid polymer may be combined with the cellulose nanofibers to form a masterbatch, in which the mass ratio of the cellulose nanofibers to the liquid polymer may be 0.1 / 99.9-99.9 / 0.1, or 1 / 99-99 / 1, or 5 / 95-95 / 5, or 10 / 90-90 / 10, or 20 / 80-80 / 20, or 30 / 70-70 / 30, or 40 / 60-60 / 40.

[0160] The master batch may or may not contain additional components in addition to the cellulose nanofibers and the liquid polymer. Examples of the additional components include one or more of the resins exemplified in this disclosure as the resins that may be contained in the resin composition of the present embodiment. The content of the additional components in the master batch is appropriately selected within a range that does not impair the desired effects of the present invention, and may be, for example, 0.01 to 50 mass %, or 0.1 to 30 mass %.

[0161] In the resin composition, the amount of cellulose nanofibers per 100 parts by mass of resin may be, from the viewpoint of the balance between processability and mechanical properties, preferably 0.001 part by mass or more, or 0.01 part by mass or more, or 0.1 part by mass or more, or 1 part by mass or more, and preferably 100 parts by mass or less, or 80 parts by mass or less, or 70 parts by mass or less, or 50 parts by mass or less, or 30 mass% or less.

[0162] In the resin composition, the amount of liquid polymer per 100 parts by mass of resin may be, from the viewpoint of the balance between processability and mechanical properties, preferably 0.001 part by mass or more, or 0.01 part by mass or more, or 0.1 part by mass or more, or 1 part by mass or more, and preferably 100 parts by mass or less, or 80 parts by mass or less, or 70 parts by mass or less, or 50 parts by mass or less, or 30% by mass or less, or 10% by mass or less, or 8 parts by mass or less.

[0163] The amount of cellulose nanofibers relative to 100% by mass of the resin composition may be, from the viewpoint of the balance between processability and mechanical properties, preferably 0.001% by mass or more, or 0.01% by mass or more, or 0.1% by mass or more, or 1% by mass or more, and preferably 50% by mass or less, or 40% by mass or less, or 30% by mass or less, or 20% by mass or less.

[0164] In the resin composition, the content of cellulose nanofibers relative to the total of 100 mass% of cellulose nanofibers and liquid polymer is preferably 0.5 mass% or more, or 1 mass% or more, or 3 mass% or more, from the viewpoint of obtaining a good reinforcing effect of the cellulose nanofibers, and is preferably 80 mass% or less, or 60 mass% or less, or 33 mass% or less, or 30 mass% or less, or 20 mass% or less, or 10 mass% or less, from the viewpoint of obtaining good advantages from the use of the liquid polymer.

[0165] The thermal decomposition onset temperature T1 of the liquid polymer and the thermal decomposition onset temperature T2 of the cellulose nanofiber preferably satisfy the following relationship in terms of good mechanical properties, decorativeness, and appearance of the resin composition and the molded product: (T1) ≧ (T2) Meet the following.

[0166] The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T3 which is the melting point of the resin or the glass transition temperature + 70° C. of the resin preferably satisfy the following relationship in terms of good mechanical properties, decorability and appearance of the resin composition and the molded product: (T1)>(T3) Meet the following. T3 is the melting point if the resin is a crystalline resin, and is the glass transition temperature +70°C if the resin is an amorphous resin. In a particularly preferred embodiment, the thermoplastic resin is a thermoplastic resin having crystallinity (i.e., having a melting point), and the temperature T3 is the melting point of the thermoplastic resin.

[0167] The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T4 which is the melting point of the resin or the glass transition temperature + 100° C. of the resin preferably satisfy the following relationship in terms of good mechanical properties, decorability and appearance of the resin composition and the molded product: (T1)>(T4) Meet the following. T4 is the melting point if the resin is a crystalline resin, and is the glass transition temperature +100°C if the resin is an amorphous resin.

[0168] In a particularly preferred embodiment, the thermal decomposition onset temperature T1 of the liquid polymer, the thermal decomposition onset temperature T2 of the cellulose nanofiber, and the temperature T3 which is the melting point of the resin or the glass transition temperature + 70° C., satisfy the following relationship in terms of good mechanical properties, decorativeness, and appearance of the resin composition and molded product: (T1) ≧ (T2) > (T3) Meet the following.

[0169] In one aspect, the difference T1-T2 between the above T1 and the above T2 is preferably 5°C or more, or 10°C or more, or 30°C or more, from the viewpoint of avoiding process constraints resulting from the use of liquid polymers because liquid polymers are less susceptible to thermal degradation than cellulose nanofibers, and is preferably 200°C or less, or 150°C or less, or 100°C or less, from the viewpoint of easy availability of liquid polymers.

[0170] In one aspect, the difference T1-T3 between the above T1 and the above T3 is preferably 30°C or more, or 50°C or more, or 70°C or more from the viewpoint of avoiding thermal deterioration of the liquid polymer due to heating during the production and processing of the resin composition and improving the mechanical properties, decoratability and appearance of the resin composition and the molded article obtained by molding it, and is preferably 200°C or less, or 150°C or less, or 100°C or less from the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article.

[0171] In one aspect, the difference T2-T3 between the above T2 and the above T3 is preferably 30°C or more, or 50°C or more, or 70°C or more, from the viewpoint of avoiding thermal degradation of the cellulose nanofiber due to heating during the production and processing of the resin composition and improving the mechanical properties, decoratability and appearance of the resin composition and the molded article obtained by molding it, and is preferably 200°C or less, or 150°C or less, or 100°C or less, from the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article.

[0172] In one aspect, the difference T1-T4 between the above T1 and the above T4 is, from the viewpoint of avoiding thermal deterioration of the liquid polymer due to heating during the production and processing of the resin composition and improving the mechanical properties, decoratability and appearance of the resin composition and the molded article obtained by molding it, preferably greater than 0°C, or 20°C or more, or 40°C or more, and from the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article, preferably 170°C or less, or 120°C or less, or 70°C or less.

[0173] In one aspect, the difference T2-T4 between the above T2 and the above T4 is, from the viewpoint of avoiding thermal degradation of the cellulose nanofibers due to heating during the production and processing of the resin composition and improving the mechanical properties, decoratability and appearance of the resin composition and the molded article obtained by molding it, preferably greater than 0°C, or 20°C or more, or 40°C or more; and from the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article, preferably 170°C or less, or 120°C or less, or 70°C or less.

[0174] <Method for producing resin composition> One aspect of the present invention also provides a method for producing a resin composition containing cellulose nanofibers, a resin, and a liquid polymer. In one aspect, the method includes heating and kneading a mixture containing cellulose nanofibers, a resin, and a liquid polymer. The liquid polymer can function as a dispersant for dispersing cellulose nanofibers well in the resin, and tends to have excellent cellulose nanofiber aggregation suppression ability and heat resistance compared to, for example, liquid non-polymer materials. By using such a liquid polymer, when producing the resin composition of this embodiment, heating and kneading can be sufficiently performed without concern for thermal deterioration of each component, so that the cellulose nanofibers can be well dispersed in the resin. The resin composition produced in this manner is advantageous for forming a molded body that has excellent mechanical properties and is also excellent in decorativeness and aesthetics due to its high surface smoothness.

[0175] Examples of the heating and kneading method include a method in which a master batch containing cellulose nanofibers and a liquid polymer is prepared in advance and then kneaded with a resin, and a method in which the cellulose nanofibers, resin, and liquid polymer are simultaneously or sequentially fed into a kneader and kneaded.

[0176] The heating and kneading method is as follows: A method in which cellulose nanofibers, a liquid polymer, and optionally additional components are mixed to produce a master batch, which is then mixed with a resin monomer to carry out a resin polymerization reaction, the resulting resin composition is extruded into a strand shape, and cooled and solidified in a water bath to obtain a pellet-shaped molded product; - A method in which a mixture of a resin and the above master batch is melt-kneaded using a single-screw or twin-screw extruder, extruded into a strand shape, and cooled and solidified in a water bath to obtain a pellet-shaped molded product; - A method in which a mixture of a resin and the above master batch is melt-kneaded using a single-screw or twin-screw extruder, extruded into a rod or tube, and cooled to obtain an extrusion molded product; - A method of melt-kneading a mixture of a resin and the above-mentioned masterbatch using a single-screw or twin-screw extruder, and extruding the mixture through a T-die to obtain a sheet or film-like molded product; In a preferred embodiment, a mixture of the resin and the master batch is melt-kneaded using a single-screw or twin-screw extruder, extruded into a strand shape, and cooled and solidified in a water bath to obtain a pellet-shaped molded product. For example, a master batch that has been delivered so as to have a desired ratio with the resin may be added to and mixed with the resin, and then the mixture may be melt-kneaded.

[0177] The master batch can be produced by mixing the components constituting the master batch using a stirring means such as a rotation / revolution mixer, a planetary mixer, a homogenizer, a propeller type stirrer, a rotary stirrer, an electromagnetic stirrer, an open roll, a Banbury mixer, a single screw extruder, or a twin screw extruder. In addition, the mixture may be stirred under heating in order to efficiently perform shearing. Mixing using a homogenizer is preferred because it can promote dispersion by applying high shearing force and pressure. The order of addition of the components during mixing is not limited, but for example, (1) A method of simultaneously adding and mixing cellulose nanofibers, a liquid polymer, and optionally additional components; (2) A method in which the components other than the liquid polymer are mixed in advance to obtain a premixture, and then the premixture is mixed with the liquid polymer; etc.

[0178] For the melt kneading to obtain the resin composition, an extruder such as a single screw extruder or a twin screw extruder can be used as described above, but a twin screw extruder is preferred in terms of controlling the dispersibility of the cellulose nanofibers. The L / D ratio, obtained by dividing the cylinder length (L) of the extruder by the screw diameter (D), is preferably 30 or more, and particularly preferably 40 or more. The screw rotation speed during kneading is preferably in the range of 50 to 800 rpm, and more preferably in the range of 100 to 600 rpm.

[0179] Each screw in the cylinder of the extruder is optimized by combining a conveying screw with an elliptical two-wing screw shape, a kneading element called a kneading disk, and the like.

[0180] The minimum processing temperatures recommended by thermoplastic resin suppliers are 255 to 270°C for polyamide 66, 225 to 240°C for polyamide 6, 225 to 240°C for polybutylene terephthalate, 170 to 190°C for polyacetal resin, and 160 to 180°C for polypropylene. The heating temperature setting is preferably in the range of 20°C higher than these recommended minimum processing temperatures. By setting the mixing temperature in this temperature range, the cellulose nanofibers and the resin can be mixed uniformly.

[0181] <Shape of resin composition> The resin composition of the present embodiment can be provided in various shapes. Specifically, resin pellets, sheets, fibers, plates, rods, etc. can be mentioned, but the resin pellet shape is preferred from the viewpoint of ease of post-processing and ease of transportation. Preferred resin pellet shapes include round, elliptical, and cylindrical shapes, and the shape may vary depending on the cutting method used during extrusion processing. For example, pellets cut by a cutting method called underwater cutting are often round, pellets cut by a cutting method called hot cutting are often round or elliptical, and pellets cut by a cutting method called strand cutting are often cylindrical. The preferred pellet diameter of round pellets is 1 mm or more and 3 mm or less. The preferred diameter of cylindrical pellets is 1 mm or more and 3 mm or less, and the preferred length is 2 mm or more and 10 mm or less. It is desirable to set the above diameter and length to be equal to or greater than the lower limit from the viewpoint of operational stability during extrusion, and it is desirable to set them to be equal to or less than the upper limit from the viewpoint of bite into the molding machine during post-processing.

[0182] The resin composition may be molded into a desired shape alone or together with other components to produce a desired molded product. The method of combining the components and the molding method are not particularly limited and may be selected according to the desired molded product. The molding method may include, but is not limited to, injection molding, extrusion molding, blow molding, inflation molding, and foam molding. Among these, the injection molding method is particularly preferred from the viewpoints of design and cost.

[0183] <Applications of resin composition> The resin composition obtained by the method of this embodiment is useful as a substitute for steel plates, fiber-reinforced plastics (e.g., carbon fiber-reinforced plastics, glass fiber-reinforced plastics, etc.), resin composites containing inorganic fillers, etc. Suitable applications of the resin composition include industrial machine parts, general machine parts, automobile / railroad / vehicle / ship / aerospace-related parts, electronic / electrical parts, building / civil engineering materials, daily necessities, sports / leisure goods, housing parts for wind power generation, containers / packaging parts, etc.

[0184] <Characteristics of resin composition> <Tensile yield strength> The tensile yield strength of the resin composition, in one embodiment, may be 20 MPa or more, or 50 MPa or more, or 80 MPa or more, and may be 300 MPa or less, or 200 MPa or less, or 150 MPa or less.

[0185] <Tensile elongation at break> The tensile elongation at break of the resin composition, in one embodiment, may be 2% or more, or 3% or more, or 5% or more, and may be 200% or less, or 100% or less, or 20% or less.

[0186] <Flexural modulus> In one embodiment, the flexural modulus of the resin composition may be 2.0 GPa or more, or 2.5 GPa or more, or 3.0 GPa or more, or 3.5 GPa or more, or 3.7 GPa or more, or 3.9 GPa or more, and may be 20.0 GPa or less, or 10.0 GPa or less, or 8.0 GPa or less.

[0187] <250℃ weight loss rate (T 250℃ )> 250℃ weight loss rate of resin composition (T 250℃ From the viewpoint of avoiding thermal degradation during molding of the resin composition and improving the mechanical strength of the molded product, the 250°C weight loss rate is preferably 1.5% or less, or 1.4% or less, or 1.3% or less. It is desirable that the 250°C weight loss rate is low, but from the viewpoint of ease of production of the resin composition, in one embodiment, the 250°C weight loss rate (T 250℃ ) is the weight loss rate when the resin composition is held at 250°C under nitrogen flow for 2 hours in TG analysis. The resin composition is heated from room temperature to 150°C at a heating rate of 10°C / min in a nitrogen flow of 100 ml / min, held at 150°C for 1 hour, then heated from 150°C to 250°C at a heating rate of 10°C / min, and held at 250°C for 2 hours. The weight W0 at the time when 250°C is reached is taken as the starting point, and the weight after holding at 250°C for 2 hours is taken as W1, and is calculated from the following formula. Weight change rate at 250℃ (%): (W1-W0) / W0×100

[0188] <Surface roughness> The resin composition of the present embodiment has low surface roughness, and thus has excellent decorative properties and appearance. The arithmetic mean surface roughness Ra of the resin composition is preferably 0.5 μm or less, or 0.4 μm or less, or 0.3 μm or less. In one aspect, from the viewpoint of ease of production of the resin composition, the arithmetic mean surface roughness Ra may be 0.001 μm or more, or 0.01 μm or more, or 0.1 μm or more. EXAMPLES

[0189] The following examples further illustrate exemplary embodiments of the present invention, but the present invention is not limited to these examples.

[0190] Evaluation method <Cellulose nanofiber> [Preparation of porous sheet] First, the concentrated cake was added to tert-butanol, and further dispersed using a mixer or the like until no aggregates were formed. The concentration was adjusted to 0.5% by mass per 0.5 g of cellulose nanofiber solids. 100 g of the resulting tert-butanol dispersion was filtered on filter paper. The filtered material was not peeled off from the filter paper, but was sandwiched together with the filter paper between two sheets of larger filter paper, and dried for 5 minutes in an oven at 150°C while pressing down the edges of the larger filter paper with a weight. The filter paper was then peeled off to obtain a porous sheet with little distortion. The air resistance of this sheet was 10 g / m2. 2 The porous sheets with a permeability of 100 sec / 100 ml or less were used as measurement samples. The basis weight W (g / m2) of the sample left standing for one day in an environment of 23°C and 50% RH 2 After measuring the air permeability, the air permeability resistance R (sec / 100ml) was measured using an Oken air permeability tester (manufactured by Asahi Seiko Co., Ltd., model EG01). 2 The value per unit area was calculated. Weight 10g / m 2Air resistance per unit (sec / 100ml) = R / W x 10

[0191] [Weight average molecular weight (Mw), number average molecular weight (Mn) and Mw / Mn ratio] 0.88 g of the porous sheet was weighed, cut into small pieces with scissors, lightly stirred, 20 mL of pure water was added, and left for one day. Next, the water and solids were separated by centrifugation. Next, 20 mL of acetone was added, lightly stirred, and left for one day. Next, the acetone and solids were separated by centrifugation. Next, 20 mL of N,N-dimethylacetamide was added, lightly stirred, and left for one day. N,N-dimethylacetamide and solids were separated again by centrifugation, and then 20 mL of N,N-dimethylacetamide was added, lightly stirred, and left for one day. N,N-dimethylacetamide and solids were separated by centrifugation, and 19.2 g of N,N-dimethylacetamide solution prepared so that lithium chloride was 8 mass percent was added to the solids, and it was stirred with a stirrer and confirmed to be dissolved by visual inspection. The solution in which the cellulose nanofibers were dissolved was filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The apparatus and measurement conditions used are as follows. Equipment: Tosoh HLC-8120 Column: TSKgel SuperAWM-H (6.0mm I.D. x 15cm) x 2 Detector: RI detector Eluent: N,N-dimethylacetamide (lithium chloride 0.2%) Flow rate: 0.6mL / min Calibration curve: Pullulan conversion For the acetylated cellulose nanofibers, the weight average molecular weight (Mw), number average molecular weight (Mn), and Mw / Mn ratio of the raw material before acetylation were used.

[0192] [Average content of alkali-soluble polysaccharides] The alkali-soluble polysaccharide content was calculated by subtracting the α-cellulose content from the holocellulose content (Wise method) according to the method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pages 92-97, 2000) for cellulose nanofibers. The alkali-soluble polysaccharide content was calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide contents was taken as the average alkali-soluble polysaccharide content of the cellulose nanofibers. For acetylated cellulose nanofibers, the average alkali-soluble polysaccharide content of the raw material before acetylation was used.

[0193] [Crystallization degree] The porous sheet was subjected to X-ray diffraction measurement, and the crystallinity was calculated according to the following formula. Crystallinity (%)=[I (200) -I (amorphous) ] / I (200) ×100 I (200) : Diffraction peak intensity due to 200 plane (2θ=22.5°) in cellulose I crystals I (amorphous) : The halo peak intensity due to the amorphous phase in cellulose I crystals, which is the peak intensity at an angle 4.5° lower than the diffraction angle of the 200 plane (2θ=18.0°) (X-ray diffraction measurement conditions) Equipment: MiniFlex (manufactured by Rigaku Corporation) Operation axis 2θ / θ Source CuKα Measurement method: Continuous Voltage 40kV Current 15mA Starting angle 2θ=5° End angle 2θ=30° Sampling width 0.020° Scan speed: 2.0° / min Sample: A porous sheet is attached onto the sample holder.

[0194] [Number average fiber diameter] The concentrated cake was diluted to 0.01% by mass with tert-butanol, dispersed using a high-shear homogenizer (IKA, product name "Ultra Turrax T18") at a rotation speed of 15,000 rpm for 3 minutes, cast onto an osmium-deposited silicon substrate, air-dried, and measured with a high-resolution scanning electron microscope (Hitachi High-Tech, Regulus 8220). The measurement was performed by adjusting the magnification so that at least 100 cellulose fibers were observed, and the minor diameter (D) of 100 randomly selected cellulose fibers was measured, and the arithmetic average of the 100 cellulose fibers was calculated.

[0195] [Specific surface area] Approximately 0.2 g of the porous sheet was dried at 120°C for 5 hours under vacuum using a specific surface area / pore distribution measuring device (Nova-4200e, manufactured by Quantachrome Instruments). The amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen was then measured in terms of the relative vapor pressure (P / P 0 ) was measured at five points in the range of 0.05 to 0.2 (multipoint method), and then the BET specific surface area (m 2 / g) was calculated.

[0196] [Acyl Substitution Degree DS] The infrared spectrum of the porous sheet at five points was measured by the ATR-IR method using a Fourier transform infrared spectrophotometer (FT / IR-6200 manufactured by JASCO Co., Ltd.) The infrared spectrum measurement was performed under the following conditions. Accumulation count: 64 times, Wavenumber resolution: 4cm -1 , Measurement wave number range: 4000~600cm -1 , ATR crystal: Diamond, Incident angle: 45°

[0197] From the obtained IR spectrum, the IR index was calculated according to the following formula: IR index = H1730 / H1030 In the formula, H1730 and H1030 are at 1730 cm -1 , 1030cm -1(absorption band of CO stretching vibration of cellulose backbone chain) -1 and 1500cm -1 The line connecting the -1 and 1500cm -1 The line connecting these points is taken as the baseline, and the absorbance is calculated when this baseline is taken as 0. The average degree of substitution at each measurement site was calculated from the IR index according to the following formula, and the average value was taken as DS. DS = 4.13 × IR index

[0198] [DS heterogeneity ratio (CV)] The porous sheet that had been subjected to the ATR-IR measurement was frozen and crushed to prepare a powder sample of cellulose. The powder was placed on ten 2.5 mm diameter dish-shaped sample stands, the surfaces were pressed down to make them flat, and XPS measurements were performed on each. Peak separation was performed on the obtained C1s spectrum, and the DSs of each sample was calculated using the area intensity (Ixf) of the peak (286 eV) derived from the OC=O bond of the acetyl group relative to the area intensity (Ixp) of the peak (289 eV, CC bond) attributed to the carbons C2-C6 derived from the pyranose ring of cellulose, and the average was taken as the DSs of the cellulose fiber. DSs = (Ixf) x 5 / (Ixp)

[0199] The conditions used for the XPS measurement are as follows: Equipment used: ULVAC-Phi VersaProbe II Excitation source: mono.AlKα 15kV×3.33mA Analysis size: Approx. 200 μm φ Photoelectron extraction angle: 45° Capture Area Narrow scan: C 1s, O 1s Pass Energy: 23.5eV

[0200] Based on the above DS and DSs, the DS heterogeneity ratio (CV) was calculated according to the following formula. DS heterogeneity ratio (CV) = DSs / DS

[0201] [Thermal decomposition onset temperature (T D )] The thermal analysis of the porous sheet was carried out by the following measurement method. Equipment: Rigaku Thermo plus EVO2 Sample: 10 mg of circular samples were cut out from the porous sheet and placed in an aluminum sample pan. Sample size: 10mg Measurement conditions: In a nitrogen flow of 100 ml / min, the temperature was increased from room temperature to 150°C at a rate of 10°C / min, and then held at 150°C for 1 hour, after which the temperature was increased to 450°C at a rate of 10°C / min. T D Calculation method: Calculated from a graph with temperature on the horizontal axis and weight remaining rate % on the vertical axis. Starting from the weight (weight loss 0 wt%) of the porous sheet at 150°C (state where moisture is almost completely removed), the temperature was further increased, and a straight line was obtained that passed through the temperatures at 1 wt% weight loss and 2 wt% weight loss. The temperature at the point where this straight line intersects with the horizontal line (baseline) that passes through the starting point of 0 wt% weight loss was determined as the thermal decomposition onset temperature (T D ) was decided.

[0202] [1wt% weight loss temperature] Said T D The temperature at which the weight loss reached 1 wt% was calculated was taken as the 1 wt% weight loss temperature.

[0203] [Weight change rate at 250℃] Equipment: Rigaku Thermo plus EVO2 Sample: 10 mg of circular samples were cut out from the porous sheet and placed in an aluminum sample pan. Sample size: 10mg Measurement conditions: In a nitrogen flow of 100 ml / min, the temperature was increased from room temperature to 150°C at a rate of 10°C / min, and then held at 150°C for 1 hour. The temperature was then increased from 150°C to 250°C at a rate of 10°C / min, and held at 250°C for 2 hours. The weight W0 at the time when 250°C was reached was taken as the starting point, and the weight W1 after holding at 250°C for 2 hours was calculated using the following formula. Weight change rate at 250℃ (%): (W1-W0) / W0×100

[0204] <Thermoplastic resin> [Melt viscosity at melting point + 20℃] Using a twin capillary rheometer (manufactured by Malvern, model number RH7), the resin viscosity at the melting point of each resin +20°C was measured at a shear rate of 500 / s.

[0205] <Liquid polymer> [Molecular weight] The values ​​listed in the supplier's product catalogue are given in Table 2.

[0206] [Viscosity at 25℃] The viscosity of the liquid polymer was measured using a Brookfield viscometer (manufactured by Eiko Seiki Co., Ltd., model number DVNext) at a rotation speed of 10 rpm.

[0207] [Viscosity at 50℃] The jacket temperature of the Brookfield viscometer was adjusted to 50° C., and the measurement was performed at a rotation speed of 10 rpm.

[0208] [Viscosity at melting point of thermoplastic resin + 20℃] The jacket temperature of the Brookfield viscometer was adjusted to the melting point of each resin + 20° C., and the measurement was performed at a rotation speed of 10 rpm.

[0209] [Vinyl content, aromatic styrene content] The values ​​listed in the supplier's product catalogue are given in Table 2.

[0210] [Glass transition temperature] The measurement was performed according to the method described in JIS K6240.

[0211] [Thermal decomposition start temperature] 10 mg of the liquid polymer was placed in an aluminum sample pan and measured in the same manner as for cellulose nanofiber.

[0212] <Resin composition>

[0213] [Confirmation of whether liquid polymer exists between cellulose nanofiber and resin] The evaluation was carried out using a scanning transmission electron microscope (STEM) under the following conditions. The resin composition pellet was trimmed to an appropriate size, and an ultrathin section of the MD-ND cross section was prepared at a set thickness of 100 nm using a cryomicrotome. After loading this on a copper mesh, appropriate staining was applied from electronic staining such as ruthenium staining, osmium staining, and phosphotungstic acid staining to obtain a specimen for microscopy. The observation conditions for STEM were as follows. Equipment: S-5500 (Hitachi, Ltd.) Accelerating voltage: 30.0 kV Detector: BF-STEM (transmitted image) In the obtained transmission images, those having a fibrous shape were regarded as cellulose nanofibers, and the following observations were made to see whether liquid polymer was present at the interface between the cellulose nanofibers and the resin. Ten images were taken at a magnification of 50,000 times in an arbitrary field of view, and if liquid polymer was present at the interface in all images, it was judged as "present," and if no liquid polymer was observed at the interface in some or all of the images, it was judged as "absent."

[0214] [Weight loss rate of resin composition at 250°C] Measurements were performed in the same manner as for cellulose nanofiber.

[0215] [Tensile yield strength and tensile elongation at break] Tensile strength at yield and elongation at break were measured according to ISO 527-1. For molded pieces that broke before yielding, the maximum strength was used instead.

[0216] [Flexural modulus] The pellets obtained were molded using an injection molding machine under conditions conforming to JIS K6920-2 to produce multipurpose test pieces conforming to ISO294-3. The molding temperatures for injection molding were 260°C for polyamide 6, 280°C for polyamide 66, 200°C for polypropylene, and 210°C for polyacetal. The flexural modulus was measured in accordance with ISO179. Since polyamide resin changes due to moisture absorption, it was stored in an aluminum moisture-proof bag immediately after molding to suppress moisture absorption.

[0217] [Arithmetic mean surface roughness Ra] A multipurpose test piece conforming to ISO294-3 was used as a sample, and measurements were made using a laser microscope (OPTELICS, manufactured by Lasertec) in accordance with JIS B0031. The roughness curve of the central part of the sample was measured, and only a reference length (a) was cut out in the average line direction of the roughness curve. The direction of the average line of this cutout part was set as the X-axis, the direction of the vertical magnification was set as the Y-axis, and the roughness curve was expressed as y=f(x). The following formula was obtained:

number

[0218] ≪Materials used≫ <Cellulose nanofiber> CNF-A: Acetylated cellulose nanofiber 5 parts by mass of the CNF-D concentrated cake (solid content rate 20% by mass) described below and 95 parts by mass of DMSO were added to a KAPPA VITA (registered trademark) homomixer (tank size 35 L) manufactured by NETZSCH Vakumix, and dispersed at 2500 rpm (circumferential speed 12 m / s) of the homomixer, and 100 parts by mass of DMSO slurry (solid content rate 1.0% by mass) was obtained. Then, 2 parts by mass of vinyl acetate and 0.3 parts by mass of potassium carbonate were added and stirred at 40°C for 3 hours. To stop the reaction, 100 parts by mass of water were added while stirring. Then, the solid content was filtered off by filtration. 100 parts by mass of water was added to the obtained solid content, and the mixture was dispersed in a homomixer, and a washing operation of filtering was performed six times to obtain 5 parts by mass of CNF-A concentrated cake (solid content rate 20% by mass).

[0219] CNF-B: Unmodified cellulose nanofibers defibrated using a disc refiner 3 parts by mass of cotton linter pulp was immersed in 27 parts by mass of water and dispersed with a pulper. 30 parts by mass of the pulper-treated cotton linter pulp slurry (including 3 parts by mass of cotton linter pulp) was added to 170 parts by mass of water and dispersed in water (solid content rate 1.5% by mass), and the aqueous dispersion was beaten for 30 minutes using a SDR14 type lab refiner (pressure type DISK type) manufactured by Aikawa Iron Works Co., Ltd. as a disc refiner device with a clearance between discs of 1 mm to obtain a slurry (solid content concentration: 1.5% by mass). Then, the mixture was concentrated to a solid content rate of 20% by mass with a dehydrator, and 15 parts by mass of CNF-B concentrated cake was obtained.

[0220] CNF-C: Commercially available cellulose nanofiber Commercially available Celish KY100G (manufactured by Daicel Finechem) was used as the CNF-C cake.

[0221] CNF-D: Unmodified cellulose nanofibers defibrated using a disc refiner and a high-pressure homogenizer 3 parts by mass of cotton linter pulp was immersed in 27 parts by mass of water and dispersed with a pulper. 30 parts by mass of the pulper-treated cotton linter pulp slurry (including 3 parts by mass of cotton linter pulp) was added to 170 parts by mass of water to disperse the mixture in water (solid content: 1.5% by mass), and the aqueous dispersion was beaten for 30 minutes using a SDR14 lab refiner (pressure type disk type) manufactured by Aikawa Iron Works Co., Ltd. as a disk refiner device with a clearance between disks of 1 mm. Subsequently, thorough beating was performed under conditions in which the clearance was reduced to a level close to zero, to obtain a beaten aqueous dispersion (solid content concentration: 1.5% by mass). The obtained beaten aqueous dispersion was directly subjected to a high-pressure homogenizer (NSO15H manufactured by Niro Soavi Co., Ltd. (Italy)) for 10 times of refinement under an operating pressure of 100 MPa to obtain a slurry (solid content concentration: 1.5% by mass). The mixture was then concentrated using a dehydrator to a solid content of 20% by mass, yielding 15 parts by mass of a concentrated CNF-D cake.

[0222] The properties of the cellulose nanofibers are shown in Table 1.

[0223] [Table 1]

[0224] <Resin> Polyamide 6 (Ube Industries, Ltd., UBE NYLON 1013B), melting point: 225°C, ηr: 200 Pa s Polyamide 66 (Asahi Kasei Corporation, LEONA1300), melting point: 265°C, ηr: 200 Pa s Polypropylene (Prime Polymer Co., Ltd., J106G), melting point: 160°C, ηr: 1000 Pa s Polyacetal (TENAC HC450, Asahi Kasei Corporation), melting point: 165°C, ηr: 20000 Pa s

[0225] <Liquid polymer and dispersing agent> The items shown in Table 2 below were used.

[0226] [Table 2]

[0227] <Additional Ingredients> Antioxidant: BASF, Irganox 245

[0228] <Preparation of resin composition> [Examples 1 to 23] The above materials were used in the compositions shown in Tables 3 and 4, and resin compositions were prepared according to the following procedure.

[0229] The cellulose cake and the liquid polymer were dried under reduced pressure using a planetary mixer in the proportions shown in Tables 3 and 4 to obtain a dried cellulose product. The above-mentioned dried cellulose and resin were blended in the ratios shown in Tables 3 and 4, and kneaded in a twin-screw extruder to obtain cellulose-containing resin pellets as a resin composition.

[0230] [Comparative Examples 1 to 5] As shown in Table 5, a resin composition was obtained in the same manner as in Example 1, except that PEG-PPG was used instead of Liquid Polymer 1.

[0231] [Reference examples 1~4] As shown in Table 5, each resin was individually charged into a twin-screw extruder and kneaded under the same conditions as in Example 1 to obtain a resin composition. The evaluation results are shown in Tables 3 to 5.

[0232] [Table 3]

[0233] [Table 4]

[0234] [Table 5] [Industrial Applicability]

[0235] The resin composition according to the present invention can be suitably applied to various applications of resin molded articles.

Claims

1. A resin composition comprising cellulose nanofibers, a resin, and a liquid polymer having a thermal decomposition onset temperature of more than 200°C.

2. The resin composition according to claim 1 , wherein the liquid polymer is a liquid rubber.

3. The resin composition according to claim 1 , wherein the liquid polymer comprises a diene rubber.

4. The resin composition according to claim 1, wherein the liquid polymer is at least one selected from the group consisting of polybutadiene, butadiene-styrene copolymer, polyisoprene, and polychloroprene.

5. The resin composition according to claim 1, wherein the liquid polymer has a number average molecular weight of 1,000 to 80,000.

6. 2. The resin composition according to claim 1, wherein the liquid polymer has a viscosity of 100 mPa·s to 1,000,000 mPa·s at 25° C.

7. The resin composition according to claim 1, wherein the liquid polymer is a copolymer of a conjugated diene monomer and an aromatic vinyl monomer, and the amount of the aromatic vinyl monomer bonded to the conjugated diene monomer is 5 mol% to 70 mol%.

8. The resin composition according to claim 1, wherein the glass transition temperature of the liquid polymer is from -150°C to 25°C.

9. The resin composition according to claim 1 , wherein the cellulose nanofiber is a chemically modified cellulose nanofiber.

10. The resin composition according to claim 9, wherein the chemically modified cellulose nanofiber is an acylated cellulose nanofiber having an acyl substitution degree of 0.1 to 2.

0.

11. The resin composition according to claim 1, wherein the cellulose nanofibers have a number average fiber diameter of 2 nm to 1000 nm.

12. The resin composition according to claim 1, wherein the cellulose nanofibers have a thermal decomposition onset temperature of 250° C. or higher.

13. The resin composition according to claim 1 , wherein the liquid polymer is present in a form that penetrates at least a portion of the interface between the cellulose nanofibers and the resin.

14. The resin composition according to claim 1 , wherein the resin composition has a weight loss rate at 250° C. of 1.5% or less.

15. The thermal decomposition onset temperature T1 of the liquid polymer and the thermal decomposition onset temperature T2 of the cellulose nanofibers have the following relationship: (T1) ≧ (T2) The resin composition according to claim 1, which satisfies the above.

16. The resin composition according to claim 15, wherein the difference T1-T2 between T1 and T2 is 5°C or more.

17. The resin composition according to claim 1 , wherein the resin is a thermoplastic resin.

18. The resin composition according to claim 17, wherein the thermoplastic resin is at least one selected from the group consisting of polyamide-based resins, polyolefin-based resins, and polyacetal-based resins.

19. The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T3 which is the melting point or the glass transition temperature + 70° C. of the thermoplastic resin satisfy the following relationship: (T1)>(T3) The resin composition according to claim 17,

20. The resin composition according to claim 19, wherein the thermoplastic resin is a crystalline thermoplastic resin, and the temperature T3 is a melting point of the thermoplastic resin.

21. The thermal decomposition starting temperature T1 of the liquid polymer and the temperature T4 which is the melting point or the glass transition temperature + 100° C. of the thermoplastic resin satisfy the following relationship: (T1)>(T4) The resin composition according to claim 17,

22. The viscosity η50 of the liquid polymer at 50° C., the viscosity ηTm of the liquid polymer at a melting point of the thermoplastic resin + 20° C., and the melt viscosity ηr of the thermoplastic resin at a melting point of the thermoplastic resin + 20° C. have the following relationship: η50 / ηTm≧20, and 1≦ηr / η50≦1000 The resin composition according to claim 17,

23. the thermoplastic resin is a polyolefin resin, The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyolefin resin + 20° C. have the following relationship: η50 / ηTm≧20 The resin composition according to claim 17,

24. the thermoplastic resin is a polyolefin resin, The melt viscosity ηr of the polyolefin resin at a melting point of the polyolefin resin + 20° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyolefin resin + 20° C. have the following relationship: ηr / ηTm≦50000 The resin composition according to claim 17,

25. The thermoplastic resin is a polyacetal resin, The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyacetal resin + 20° C. have the following relationship: η50 / ηTm≧20 The resin composition according to claim 17,

26. The thermoplastic resin is a polyacetal resin, The melt viscosity ηr of the polyacetal-based resin at a melting point of the polyacetal-based resin + 20° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyacetal-based resin + 20° C. have the following relationship: ηr / ηTm≦100000 The resin composition according to claim 17,

27. the thermoplastic resin is a polyamide resin, The viscosity η50 of the liquid polymer at 50° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyamide-based resin + 20° C. have the following relationship: η50 / ηTm≧80 The resin composition according to claim 17,

28. the thermoplastic resin is a polyamide resin, The melt viscosity ηr of the polyamide-based resin at a melting point of the polyamide-based resin + 20° C. and the viscosity ηTm of the liquid polymer at a melting point of the polyamide-based resin + 20° C. have the following relationship: ηr / ηTm≦50000 The resin composition according to claim 17,

29. The resin composition according to claim 1, which is free of a surfactant.

30. The resin composition according to claim 1, further comprising 0.1 to 50 parts by mass of a dispersing aid per 100 parts by mass of the liquid polymer.

31. A method for producing the resin composition according to any one of claims 1 to 30, A method comprising heating and kneading a mixture comprising cellulose nanofibers, a resin, and a liquid polymer.

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