Resin composition and method for producing the same

Abstract

To provide a resin composition having excellent mechanical characteristics and a method for producing the same.SOLUTION: A method for producing a resin composition containing a polyolefin-based resin, a polyamide-based resin and cellulose nanofibers includes a first kneading step of kneading a kneading component containing a polyamide-based resin and cellulose nanofibers to obtain a masterbatch, and a second kneading step of kneading a kneading component containing the masterbatch and a polyolefin-based resin to obtain a resin composition, wherein the first kneading step and the second kneading step are continuously performed in the same device, the first kneading step is performed in the absence of a modified polyolefin-based resin, the resin composition has a continuous phase of the polyolefin-based resin and a dispersion phase of the polyamide-based resin, the dispersion phase is a non-spherical dispersion phase, and in the resin composition, at least a part of the cellulose nanofibers is interposed between the continuous phase and the dispersion phase.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 Art

[0002] Resin materials are light and have excellent processing characteristics, so they are widely used in various fields such as automotive parts, electrical and electronic parts, office equipment housings, and precision parts. However, resin alone often has insufficient mechanical properties and dimensional stability. Therefore, composites of resins and various fillers are generally used. In recent years, as such a filler, the use of cellulose nanofibers (CNF), which are natural product-derived materials, has been considered. CNF has the advantages of having excellent mechanical properties and a small environmental load. However, due to its fine structure, it has the property of being easily aggregated in a dry state, so it is produced as a dispersion liquid in which stable dispersion is possible. For example, when applying cellulose nanofibers to various uses, there are cases where the above dispersion liquid is directly mixed with a resin, and cases where the dispersion liquid is once dried and then dispersed in a dispersion medium or mixed with the resin as a dried body. However, in cellulose nanofibers, aggregation due to hydrogen bonding between cellulose molecules is extremely strong. Therefore, various methods for suppressing the aggregation of cellulose nanofibers have been proposed conventionally.

[0003] Particularly, when a highly hydrophobic resin such as a polyolefin resin is selected as a matrix as a thermoplastic resin, it is extremely difficult to uniformly disperse cellulose fibers in the matrix resin because cellulose fibers are hydrophilic. Therefore, various attempts have been made to improve the affinity of the interface between the matrix resin and cellulose fibers.

[0004] For example, Patent Document 1 describes that in order to disperse cellulose nanofibers in a thermoplastic resin without aggregating them, a masterbatch in which the solubility parameters of the cellulose nanofibers, the thermoplastic resin, and the compatibilizer are adjusted within a specific range is produced, and then this is mixed with a diluting resin to obtain a thermoplastic resin in which the cellulose nanofibers are dispersed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The properties required for resin compositions containing cellulose nanofibers have been becoming more and more advanced year by year. In particular, molded articles formed from resin compositions are required to have particularly excellent mechanical properties. The technique described in Patent Document 1 attempts to improve the dispersibility of cellulose nanofibers by means of a masterbatch in which the range of solubility parameters is adjusted, but there is still room for improvement in providing a resin composition that exhibits excellent mechanical properties due to the contribution of cellulose nanofibers.

[0007] One aspect of the present invention aims to solve the above problems and provide a resin composition having excellent mechanical properties and a method for producing the same.

Means for Solving the Problems

[0008] This disclosure includes the following aspects. [1] A method for producing a resin composition comprising a polyolefin-based resin, a polyamide-based resin, and cellulose nanofibers, comprising: a first kneading step of kneading a kneading component comprising a polyamide-based resin and cellulose nanofibers to obtain a masterbatch, and [[ID=3I]] A second kneading step involves kneading the masterbatch and a kneading component containing a polyolefin resin to obtain a resin composition. Includes, The first kneading step and the second kneading step are performed continuously within the same apparatus. The first kneading step is carried out in the absence of the modified polyolefin resin. The resin composition comprises a continuous phase of a polyolefin resin and a dispersed phase of a polyamide resin. The aforementioned dispersed phase is a non-spherical dispersed phase, A method comprising the resin composition wherein at least a portion of the cellulose nanofibers are interposed between the continuous phase and the dispersed phase. [2] The method according to embodiment 1, wherein the resin composition has a Ferret major axis / Ferret minor axis ratio of the dispersed phase of 1.5 or more. [3] The method according to embodiment 1 or 2, wherein the resin composition has a roughness of 0.01 to 0.9 of the dispersed phase. [4] The method according to any one of embodiments 1 to 3, wherein at least a portion of the cellulose nanofibers interposed between the continuous phase and the dispersed phase is in contact only with the continuous phase at one end in the fiber length direction and in contact only with the dispersed phase at the other end in the fiber length direction. [5] The method according to any one of embodiments 1 to 4, wherein the resin composition has a ratio Lp / Lc of the spherical equivalent diameter Lp of the dispersed phase to the fiber length Lc of the cellulose nanofibers, which is 0.001 to 0.1. [6] The method according to any one of embodiments 1 to 5, wherein the weight-average molecular weight of the polyamide resin is 1,000 to 100,000. [7] The method according to any one of embodiments 1 to 6, wherein the terminal amino group concentration [NH2] of the polyamide resin is 1 μmol / g to 150 μmol / g. [8] The method according to any one of embodiments 1 to 7, wherein the concentration of terminal carboxyl groups [COOH] of the polyamide resin is 20 μmol / g to 500 μmol / g. [9] The method according to any one of embodiments 1 to 8, wherein the polyamide resin has an aromatic skeleton and an aliphatic skeleton.

[10] The method according to any one of embodiments 1 to 9, wherein the polyamide resin is polyamide 6I.

[11] The method according to any one of embodiments 1 to 10, wherein the difference Tg1-Tg2 between the glass transition temperature Tg1 of the polyamide resin and the glass transition temperature Tg2 of the polyolefin resin is greater than 80°C.

[12] The method according to any one of embodiments 1 to 11, wherein the polyolefin resin is a polypropylene resin.

[13] The method according to embodiment 12, wherein the weight-average molecular weight of the polypropylene resin is 10,000 to 300,000.

[14] The method according to embodiment 12 or 13, wherein the melt flow rate (MFR) of the polypropylene resin at 230°C is 3 g / 10 min to 30 g / 10 min.

[15] The method according to any one of embodiments 1 to 14, wherein the number-average fiber diameter of the cellulose nanofibers is 2 nm to 1000 nm.

[16] The method according to any one of embodiments 1 to 15, wherein the cellulose nanofiber is a chemically modified cellulose nanofiber.

[17] The method according to embodiment 16, wherein the chemically modified cellulose nanofiber is acetylated cellulose nanofiber.

[18] The method according to embodiment 16 or 17, wherein the degree of acyl substitution (DS) of the chemically modified cellulose nanofiber is 0.1 to 2.0.

[19] The method according to any one of embodiments 1 to 18, wherein the resin composition comprises 100 parts by mass of an unmodified polyolefin resin, 0.1 to 50 parts by mass of a polyamide resin, and 0.1 to 50 parts by mass of cellulose nanofibers.

[20] The method according to any one of embodiments 1 to 19, wherein the second kneading step is carried out in the presence of a modified polyolefin resin, and the resin composition contains the modified polyolefin resin. Including doing,

[21] The method according to embodiment 20, wherein the modified polyolefin resin is an acid-modified polyolefin resin.

[22] The method according to embodiment 21, wherein the acid-modified polyolefin resin is an acid-modified polypropylene resin.

[23] The method according to embodiment 21 or 22, wherein the acid value of the acid-modified polyolefin resin is 1 mg KOH / g to 200 mg KOH / g.

[24] The method according to any one of embodiments 21 to 23, wherein the ratio of the carboxyl group concentration [COOH]MAH of the acid-modified polyolefin resin to the terminal amino group concentration [NH2] of the polyamide resin, [COOH]MAH / [NH2], is greater than 0.1.

[25] The method according to any one of embodiments 1 to 24, wherein the first kneading step and / or the second kneading step are carried out in the presence of a dispersant, and the resin composition contains the dispersant.

[26] A resin composition comprising a polyolefin resin, a polyamide resin, and cellulose nanofibers, The resin composition comprises a continuous phase of the polyolefin resin and a dispersed phase of the polyamide resin. The aforementioned dispersed phase is a non-spherical dispersed phase, A resin composition in which at least a portion of the cellulose nanofibers is interposed between the continuous phase and the dispersed phase.

[27] The resin composition according to embodiment 26, wherein the ratio of the Ferret major axis to the Ferret minor axis of the dispersed phase is 1.5 or more.

[28] The resin composition according to embodiment 26 or 27, wherein the degree of unevenness of the dispersed phase is 0.01 to 0.9.

[29] The resin composition according to any one of embodiments 26 to 28, wherein at least a portion of the cellulose nanofibers interposed between the continuous phase and the dispersed phase are in contact only with the continuous phase at one end in the fiber length direction and in contact only with the dispersed phase at the other end in the fiber length direction.

[30] The resin composition according to any one of embodiments 26 to 29, wherein the ratio Lp / Lc of the spherical equivalent diameter Lp of the dispersed phase to the fiber length Lc of the cellulose nanofibers is 0.001 to 0.1.

[31] The resin composition according to any one of embodiments 26 to 30, wherein the weight-average molecular weight of the polyamide resin is 1,000 to 100,000.

[32] The resin composition according to any one of embodiments 26 to 31, wherein the concentration of terminal amino groups [NH2] of the polyamide resin is 1 μmol / g to 150 μmol / g.

[33] The resin composition according to any one of embodiments 26 to 32, wherein the concentration of terminal carboxyl groups [COOH] of the polyamide resin is 20 μmol / g to 500 μmol / g.

[34] The resin composition according to any one of embodiments 26 to 33, wherein the polyamide resin has an aromatic skeleton and an aliphatic skeleton.

[35] The resin composition according to any one of embodiments 26 to 34, wherein the polyamide resin is polyamide 6I.

[36] The resin composition according to any one of embodiments 26 to 35, wherein the difference Tg1-Tg2 between the glass transition temperature Tg1 of the polyamide resin and the glass transition temperature Tg2 of the polyolefin resin is greater than 80°C.

[37] The resin composition according to any one of embodiments 26 to 36, wherein the polyolefin resin is a polypropylene resin.

[38] The resin composition according to embodiment 37, wherein the weight-average molecular weight of the polypropylene resin is 10,000 to 300,000.

[39] The resin composition according to embodiment 37 or 38, wherein the melt flow rate (MFR) of the polypropylene resin at 230°C is 3 g / 10 min to 30 g / 10 min.

[40] The resin composition according to any one of embodiments 26 to 39, wherein the number average fiber diameter of the cellulose nanofibers is 2 nm to 1000 nm.

[41] The resin composition according to any one of embodiments 26 to 40, wherein the cellulose nanofibers are chemically modified cellulose nanofibers.

[42] The resin composition according to embodiment 41, wherein the chemically modified cellulose nanofiber is acetylated cellulose nanofiber.

[43] The resin composition according to embodiment 41 or 42, wherein the degree of acyl substitution (DS) of the chemically modified cellulose nanofiber is 0.1 to 2.0.

[44] A resin composition according to any one of embodiments 26 to 43, comprising 100 parts by mass of an unmodified polyolefin resin, 0.1 to 50 parts by mass of a polyamide resin, and 0.1 to 50 parts by mass of cellulose nanofibers.

[45] The resin composition according to any one of embodiments 26 to 44, further comprising a modified polyolefin resin.

[46] The resin composition according to embodiment 45, wherein the modified polyolefin resin is an acid-modified polyolefin resin.

[47] The resin composition according to embodiment 46, wherein the acid-modified polyolefin resin is an acid-modified polypropylene resin.

[48] ​​The resin composition according to embodiment 46 or 47, wherein the acid value of the acid-modified polyolefin resin is 1 mg KOH / g to 200 mg KOH / g.

[49] The resin composition according to any one of embodiments 46 to 48, wherein the ratio of the carboxyl group concentration [COOH]MAH of the acid-modified polyolefin resin to the terminal amino group concentration [NH2] of the polyamide resin is greater than 0.1.

[50] A resin composition according to any one of embodiments 26 to 49, further comprising a dispersant. [Effects of the Invention]

[0009] According to one aspect of the present invention, a resin composition with excellent mechanical properties and a method for producing the same can be provided. [Modes for carrying out the invention]

[0010] Exemplary embodiments of the present invention (hereinafter also referred to as "these embodiments") will be described in detail below, but the present invention is not limited to these embodiments. Unless otherwise specified, the characteristic values ​​of this disclosure are measured by the methods described in the [Examples] section of this disclosure or by methods that would be understood to those skilled in the art to be equivalent thereto.

[0011] ≪Resin composition≫ One aspect of the present invention provides a resin composition comprising a polyolefin resin, a polyamide resin, and cellulose nanofibers. In one aspect, the resin composition has a continuous phase of polyolefin resin and a dispersed phase of polyamide resin.

[0012] In one embodiment, the resin composition comprises 100 parts by mass of a polyolefin resin (100 parts by mass of an unmodified polyolefin resin in one embodiment), 0.1 to 50 parts by mass of a polyamide resin, and 0.1 to 50 parts by mass of cellulose nanofibers.

[0013] In one embodiment, cellulose nanofibers in the resin composition exist as microfibrils or bundles of microfibrils. In another embodiment, at least a portion of the cellulose nanofibers are interposed between a continuous phase and a dispersed phase. Cellulose nanofibers are inherently hydrophilic due to their hydroxyl groups, while the properties of the thermoplastic resin that constitutes the resin composition in combination with the cellulose nanofibers vary depending on the type of thermoplastic resin selected. The inventors have found that, in the production of a resin composition containing cellulose nanofibers, by having the cellulose nanofibers present in a unique distribution form within the resin composition, a high degree of compatibility in mechanical properties, more specifically, tensile yield strength, tensile elongation at break, and flexural modulus, can be achieved.

[0014] Polyolefin resins, especially unmodified polyolefin resins, generally have strong hydrophobicity. On the other hand, polyamide resins have a certain degree of hydrophilicity because they contain hydrophilic groups such as amino groups and carboxyl groups. When polyolefin resins and polyamide resins are mixed, one generally forms a continuous phase and the other forms a nearly spherical dispersed phase.

[0015] When producing a resin composition by further mixing cellulose nanofibers with polyolefin resins and polyamide resins, the dispersion state of the cellulose nanofibers in the resin composition can be controlled by the combination of the properties of the cellulose nanofibers (size, chemical modification state, etc.) and the mixing conditions. Conventionally, in cellulose nanofiber-containing resin compositions, the main focus has been on uniformly dispersing the cellulose nanofibers in the resin. However, the inventors have found that interposing cellulose nanofibers between the continuous phase and the dispersed phase unexpectedly improves the mechanical properties of the resin composition.

[0016] In areas where cellulose nanofibers are interposed between the continuous phase and the dispersed phase, the two phases are not in direct contact. Although not bound by theory, it is thought that when cellulose nanofibers are interposed between the continuous phase and the dispersed phase, the increased contact area between the dissimilar materials compared to when the two phases are in direct contact leads to an anchoring effect, resulting in improved resistance to delamination between the dissimilar materials and, consequently, improved mechanical properties of the resin composition.

[0017] In one embodiment, the dispersed phase of a polyamide resin is a non-spherical dispersed phase. In this disclosure, a non-spherical dispersed phase means a phase in which the Ferret major axis / Ferret minor axis ratio is greater than 1.1. In this disclosure, the Ferret major axis of the dispersed phase is the maximum distance between parallel lines when the projected image of the dispersed phase is sandwiched between parallel lines in a certain direction, and the Ferret minor axis of the dispersed phase is the minimum distance between parallel lines when the projected image of the dispersed phase is sandwiched between parallel lines in a certain direction. In one embodiment, a non-spherical dispersed phase means a phase in which the degree of roughness measured by the method described later is 0.9 or less. A non-spherical dispersed phase can be formed when a polyamide resin and a polyolefin resin are mixed in the presence of cellulose nanofibers, and the dispersion behavior of the polyamide resin is appropriately adjusted by the action of cellulose nanofibers. Examples of factors that can greatly contribute to controlling the shape of the dispersed phase include the size of the cellulose nanofibers, the order of addition of the kneading components to the kneader, the kneading conditions, the chemical structure of the dispersed phase and the continuous phase, and the ratio of the dispersed phase to the continuous phase. The formation of a non-spherical dispersed phase by the polyamide resin increases the contact area between the polyamide resin and the cellulose nanofiber or polyolefin resin. This is thought to contribute to improved peel resistance between dissimilar materials and, consequently, to improved mechanical properties of the resin composition.

[0018] The ratio of the long diameter to the short diameter of the Ferret ferret is preferably 1.2 or higher, or 1.3 or higher, or 1.4 or higher, or 1.5 or higher, from the viewpoint of obtaining good mechanical properties of the resin composition, and in one embodiment, it is 10 or lower, or 5 or lower, or 3 or lower, from the viewpoint of ease of manufacturing the resin composition.

[0019] In electron microscope cross-sectional observation of a resin composition, the degree of roughness of the dispersed phase, calculated by the following formula, is 0.9 or less in one embodiment. The degree of roughness may be 0.01 or greater in one embodiment. The degree of roughness is 1 when the dispersed phase is spherical. For example, the degree of roughness is 0.99 when the dispersed phase is an ellipsoid with a major axis / minor axis ratio of 1.2. A degree of roughness of 0.9 or less indicates that the dispersed phase does not have a fixed shape such as a sphere or ellipsoid, but rather an irregular shape with protrusions, points, etc. Formula: Roughness = [cross-sectional area / (outer circumference length) 2)] × 4π

[0020] In one embodiment, at least a portion of the cellulose nanofibers (in one embodiment, at least a portion of the cellulose nanofibers interposed between the continuous phase and the dispersed phase) are in contact only with the continuous phase at one end in the fiber length direction (i.e., they exist in the continuous phase) and in contact only with the dispersed phase at the other end in the fiber length direction (i.e., they exist in the dispersed phase). Cellulose nanofibers in this manner are advantageous for improving the mechanical properties of the resin composition.

[0021] In electron microscope cross-sectional observation of the resin composition, the area ratio of cellulose nanofibers present in or at least in contact with the dispersed phase relative to 100% of the total amount of cellulose nanofibers is preferably 0.1% by mass or more, 1% by mass or more, or 10% by mass or more, from the viewpoint of obtaining a good reinforcing effect by cellulose nanofibers, and preferably 90% by mass or less, from the viewpoint of ease of manufacturing the resin composition.

[0022] In the resin composition, the ratio Lp / Lc of the spherical equivalent diameter Lp of the dispersed phase to the fiber length Lc of the cellulose nanofiber is preferably 0.001 or more, or 0.002 or more, from the viewpoint of obtaining a good effect of making the dispersed phase non-spherical by the cellulose nanofiber and from the viewpoint of obtaining a good inherent good property (heat resistance, etc.) of the polyamide resin, and preferably 0.1 or less, or 0.05 or less, or 0.03 or less, or 0.01 or less, or 0.005 or less.

[0023] The equivalent spherical diameter Lp may, in one embodiment, be 0.1 μm or more, or 0.5 μm or more, or 1 μm or more, and in one embodiment, it may be 20 μm or less, or 10 μm or less, or 5 μm or less.

[0024] The following describes preferred examples of each component of the resin composition.

[0025] <Cellulose nanofiber> Cellulose nanofibers may be obtained from various cellulose fiber raw materials selected from natural cellulose and regenerated cellulose. As natural cellulose, wood pulp obtained from wood species (hardwood or softwood), non-wood pulp obtained from non-wood species (cotton, bamboo, hemp, bagasse, kenaf, cotton linter, sisal, straw, etc.), and cellulose fiber aggregates produced by animals (e.g., sea squirts), algae, or microorganisms (e.g., acetic acid bacteria) can be used. As regenerated cellulose, regenerated cellulose fibers (viscose, cupro, 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 needed by beating, fibrillation, or micronization using mechanical force such as grinders and refiners to adjust the fiber diameter, fiber length, degree of fibrillation, etc., or by bleaching and purifying with chemicals to adjust the content of components other than cellulose (acid-insoluble components such as lignin, alkali-soluble polysaccharides such as hemicellulose, etc.).

[0026] Cellulose nanofibers are obtained by mechanically micronizing cellulose raw materials using a dry or wet process. This micronization process may be performed using a single device one or more times, or using multiple devices, each one or more times. The equipment used for micronization is not particularly limited, but examples include high-speed rotary, colloidal mill, high-pressure, roll mill, and ultrasonic types of equipment. High-pressure or ultra-high-pressure homogenizers, refiners, beaters, PFI mills, kneaders, dispersers, high-speed defibrators, grinders (stone mill type grinders), ball mills, vibratory mills, bead mills, conical refiners, disc refiners, single-screw, twin-screw or multi-screw kneaders / extruders, homomixers under high-speed rotation, refiners, defibrators, beaters, friction grinders, high-shear fibrilators (e.g., Cavitron rotor / starter devices), dispersers, homogenizers (e.g., microfluidizers), etc., which use metal or blades to act on pulp fibers around a rotating shaft, or those that use friction between pulp fibers.

[0027] In one embodiment, cellulose nanofibers can be obtained as a slurry. The slurry can be prepared by dispersing and micronizing cellulose fiber raw materials in water and / or other media (e.g., organic solvents, inorganic acids, bases and / or ionic liquids).

[0028] The organic solvent used in the aforementioned micronization process is not particularly limited, but examples include: alcohols with 1 to 20 carbon atoms, preferably 1 to 4 carbon atoms, such as methanol, ethanol, and propanol; glycol ethers with 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, such as methyl cellosolve and propylene glycol monomethyl ether; ethers with 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; and Examples include ketones with 3 to 20 carbon atoms, preferably 3 to 6 carbon atoms, such as ethyl isobutyl ketone; linear or branched saturated or unsaturated hydrocarbons with 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 with 1 to 20 carbon atoms, such as formic acid, acetic acid, and lactic acid; esters with 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 dimethyl sulfoxide. These can be used individually or in combination of two or more, but from the viewpoint of ease of operation in the micronization process, alcohols with 1 to 6 carbon atoms, glycol ethers with 2 to 6 carbon atoms, ethers with 2 to 8 carbon atoms, ketones with 3 to 6 carbon atoms, lower alkyl ethers with 2 to 5 carbon atoms, carboxylic acids with 1 to 8 carbon atoms, esters with 2 to 6 carbon atoms, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide are preferred.

[0029] Examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and boric acid. However, from the viewpoint of efficiency of defibrillation and ease of handling, it is preferable to use one or more selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid.

[0030] Examples of bases include hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide; carbonates such as sodium carbonate, potassium carbonate, and calcium carbonate; and organic amines such as ammonia, triethylamine, and triethanolamine. However, from the viewpoint of efficiency of defibrillation and ease of handling, it is preferable to use one or more selected from the group consisting of hydroxides, carbonates, and organic amines.

[0031] In this disclosure, an ionic liquid refers to a salt of a liquid containing an organic ion in at least one of its cation and anion portions, with a melting point of ions only of 100°C or lower. Preferably, the ionic liquid 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 in its cation portion.

[0032] In particular, ionic liquids having an imidazolium skeleton, for example, the following formula (1): [ka] (In the formula, R1 and R2 each independently represent an alkyl group or allyl group having 1 to 8 carbon atoms, and X represents an anion.) The imidazolium-based ionic liquid shown is more preferable than other ionic liquids because it has a relatively low melting point, a wide temperature range in which it exists as a liquid, maintains fluidity even at low temperatures, and has excellent thermal stability. From the viewpoint of defibrillability, the number of carbon atoms in R1 and R2 is more preferably 4 or less, even more preferably 3 or less, and most preferably 2 or less.

[0033] The anionic component is a halide ion (Cl - , Br - , I - (etc.), carboxylate anions (for example, carboxylate anions with a total of 1 to 3 carbon atoms, e.g., C2H5CO2) - CH3CO2 - , HCO2 -Pseudohalide ions (i.e., monovalent ions having properties similar to halide ions, such as CN - , SCN - , OCN - , ONC - , N3 - etc.), sulfonate anions, organic sulfonate anions (such as methanesulfonate anion), phosphate anions (such as ethyl phosphate anion, methyl phosphate anion, hexafluorophosphate anion), borate anions (such as tetrafluoroborate anion), perchlorate anions, etc. From the viewpoint of fiber disintegration property, halide ions and carboxylate anions are preferred.

[0034] Examples of imidazolium-based 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, 1-propyl-3-methylimidazolium bromide, etc.

[0035] While it is possible to defibrillate cellulose fiber raw materials using only ionic liquids, if the solubility of the ionic liquid is too high and there is a risk of dissolving cellulose nanofibers, it is preferable to add water and / or an organic solvent to the ionic liquid. The type of organic solvent to be added should be appropriately selected considering its compatibility with the ionic liquid, affinity with cellulose, solubility of the mixed solvent in the cellulose fiber raw materials, viscosity, etc., but it is preferable to select one or more from the group consisting of N,N-dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidone, dimethyl sulfoxide, acetonitrile, methanol, and ethanol.

[0036] The total amount of water and / or other media used in the micronization process is not particularly limited, as long as it is an effective amount that can disperse the cellulose fiber raw material. However, it is preferably 1 mass or more, more preferably 10 mass or more, even more preferably 50 mass or more, preferably 10,000 mass or less, more preferably 5,000 mass or less, even more preferably 2,000 mass or less, and particularly preferably 1,000 mass or less, relative to the cellulose fiber raw material.

[0037] Since cellulose fiber raw materials contain alkali-soluble components and sulfuric acid-insoluble components (such as lignin), these components may be reduced through purification processes such as deligninization by pulping and bleaching. On the other hand, purification processes such as deligninization by pulping and bleaching cleave the molecular chains of cellulose, changing the weight-average molecular weight and number-average molecular weight. Therefore, it is desirable that the purification and bleaching processes of cellulose fiber raw materials be controlled so that the weight-average molecular weight of cellulose nanofibers and the ratio of weight-average molecular weight to number-average molecular weight are within an appropriate range.

[0038] Furthermore, there are concerns that the purification process, such as deligninization through pulping, and the bleaching process may reduce the molecular weight of cellulose nanofibers, and that the cellulose fiber raw material may be altered, increasing the proportion of alkali-soluble components. Since alkali-soluble components have poor heat resistance, it is desirable that the purification and bleaching processes of the cellulose fiber raw material be controlled so that the amount of alkali-soluble components contained in the cellulose fiber raw material remains below a certain value.

[0039] 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 borate esters, organic esters such as acetylated and propionylated esters, ethers such as methyl ethers, hydroxyethyl ethers, hydroxypropyl ethers, hydroxybutyl ethers, carboxymethyl ethers, and cyanoethyl ethers, and TEMPO oxides obtained by oxidizing the primary hydroxyl groups of cellulose can be used as the cellulose fiber raw material.

[0040] [Number-average fiber length, number-average fiber diameter, and L / D ratio] In one embodiment, the number-average fiber length of cellulose nanofibers can favorably influence the distribution of cellulose nanofibers in a resin composition. More specifically, setting the number-average fiber length within a specific range may be advantageous when interposing cellulose nanofibers between the continuous phase of a polyolefin resin and the dispersed phase of a polyamide resin. Although not bound by theory, it is thought that cellulose nanofibers with a controlled number-average fiber length within a specific range exhibit appropriate thixotropy during the kneading process in the production of the resin composition, attracting them between the polyolefin resin phase and the polyamide resin phase, thereby allowing for the uneven distribution of cellulose nanofibers near the boundary between the continuous phase and the dispersed phase.

[0041] In one embodiment, the number-average fiber length of the cellulose nanofibers is preferably 30 μm or more, 50 μm or more, or 100 μm or more, from the viewpoint of exhibiting the property-improving effect of cellulose nanofibers well and, in particular, from the viewpoint of well controlling the distribution state of cellulose nanofibers in the resin composition, and preferably 750 μm or less, 700 μm or less, 650 μm or less, or 600 μm or less, from the viewpoint of controlling the distribution state of cellulose nanofibers in the resin composition.

[0042] In one embodiment, 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. More preferably, the number-average fiber diameter of the cellulose nanofibers is 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.

[0043] The number-average fiber length (L) / number-average fiber diameter (D) ratio of 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, from the viewpoint of effectively improving the mechanical properties of the resin composition containing cellulose nanofibers with a small amount of cellulose nanofibers. There is no particular upper limit, but from the viewpoint of ease of handling, it is preferably 5000 or less, or 3000 or less, or 2000 or less, or 1000 or less.

[0044] In one embodiment, the number-average fiber diameter (D), number-average fiber length (L), and L / D ratio of the cellulose nanofibers of this disclosure are values ​​measured using a scanning electron microscope (SEM) by the following procedure. An aqueous dispersion of cellulose fibers is replaced with tert-butanol, diluted to 0.001-0.1% by mass, dispersed using a high-shear homogenizer (e.g., IKA product, trade name "Ultra-Turrax T18") under processing conditions: rotation speed 15,000 rpm × 3 minutes, cast onto an osmium-deposited silicon substrate, and air-dried. This is used as the measurement sample and measured using a high-resolution scanning electron microscope (SEM). Specifically, the length (L) and diameter (D) of 100 randomly selected fibrous materials are measured in an observation field adjusted to the magnification so that at least 100 fibrous materials can be observed, and the ratio (L / D) is calculated. For the cellulose fibers, the number-average values ​​of length (L), diameter (D), and ratio (L / D) are calculated.

[0045] [Crystallization] The crystallinity of the cellulose nanofibers is preferably 55% or higher. When the crystallinity is within this range, the mechanical properties (strength, dimensional stability) of the cellulose itself are high, and therefore, when cellulose nanofibers are dispersed in a resin, the resin composition tends to have high strength and dimensional stability. A more preferable lower limit for the crystallinity is 60%, even more preferably 70%, and most preferably 80%. There is no particular upper limit to the crystallinity of the cellulose nanofibers; higher is preferable, but from a production standpoint, a preferable upper limit is 99%.

[0046] The degree of crystallinity referred to here, when the cellulose is type I cellulose crystal (derived from natural cellulose), can be determined by the Segal method from the diffraction pattern (2θ / deg. of 10 to 30) obtained by measuring the sample by wide-angle X-ray diffraction, using the following formula. Crystallinity (%)=[I (200) -I (amorphous) ] / I (200) ×100 I (200) :Diffraction peak intensity at the 200 plane (2θ=22.5°) in cellulose type I crystals I (amorphous) : The halo peak intensity due to amorphous material in type I cellulose crystals, specifically the peak intensity at an angle 4.5° lower than the diffraction angle of the 200 plane (2θ = 18.0°).

[0047] Furthermore, if the cellulose is a type II cellulose crystal (derived from regenerated cellulose), the degree of crystallinity can be determined by the following formula using wide-angle X-ray diffraction, from the absolute peak intensity h0 at 2θ=12.6°, which is attributed to the (110) plane peak of the type II cellulose crystal, and the peak intensity h1 from the baseline at this interplanar spacing. Crystallinity (%) =h1 / h0 ×100

[0048] [Crystal polymorphism] Known crystalline polymorphs of cellulose include type I, type II, type III, and type IV. Among these, types I and II are particularly widely used, while types III and IV, although obtained on a laboratory scale, are not widely used on an industrial scale. The cellulose nanofibers of this disclosure have relatively high structural mobility, and by dispersing these cellulose nanofibers in a resin, a resin composition with a lower coefficient of thermal expansion and superior strength and elongation during tensile and bending deformation can be obtained. Therefore, cellulose nanofibers containing cellulose type I crystals or cellulose type II crystals are preferred, and cellulose nanofibers containing cellulose type I crystals and having a crystallinity of 55% or higher are more preferred.

[0049] [Degree of polymerization] Furthermore, the degree of polymerization of the cellulose nanofiber is preferably 100 or higher, more preferably 150 or higher, more preferably 200 or higher, more preferably 300 or higher, more preferably 400 or higher, more preferably 450 or higher, preferably 3500 or lower, more preferably 3300 or lower, more preferably 3200 or lower, more preferably 3100 or lower, and more preferably 3000 or lower.

[0050] From the viewpoint of processability and mechanical property development, it is desirable to keep the degree of polymerization of cellulose nanofibers 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 development, it is desirable that it is not too low.

[0051] The degree of polymerization of cellulose nanofibers refers to the average degree of polymerization measured according to the reduction ratio viscosity method using copper ethylenediamine solution, as described in the confirmation test (3) of the "Fifteenth Revised Japanese Pharmacopoeia Commentary (published by Hirokawa Shoten)". Furthermore, the degree of polymerization of chemically modified cellulose nanofibers may not be accurately calculated due to the presence of chemical modification groups. In such cases, the degree of polymerization of the cellulose nanofiber immediately before chemical modification, or the cellulose fiber raw material (e.g., pulp) immediately before chemical modification, may be considered as the degree of polymerization of the chemically modified cellulose nanofibers.

[0052] [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 another embodiment, the ratio of weight-average molecular weight to number-average molecular weight (Mn) (Mw / Mn) is 6 or less, or 5.4 or less. A larger weight-average molecular weight means fewer end groups in the cellulose molecule. Also, since the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) represents the width of the molecular weight distribution, a smaller Mw / Mn means fewer end groups in the cellulose molecule. Since the end groups of cellulose molecules are the starting points for thermal decomposition, particularly heat-resistant cellulose nanofibers can be obtained when the weight-average molecular weight of the cellulose molecules in the cellulose nanofiber is large, and at the same time the width of the molecular weight distribution is narrow. From the viewpoint of the availability of cellulose fiber raw materials, the weight-average molecular weight (Mw) of the cellulose nanofiber may be, for example, 600,000 or less, or 500,000 or less. The ratio of weight-average molecular weight to number-average molecular weight (Mn) (Mw / Mn) may be, for example, 1.5 or higher, or 2 or higher, from the viewpoint of ease of manufacturing cellulose nanofibers. Mw can be controlled to the above range by selecting a cellulose fiber raw material having an Mw appropriate for the purpose, and by appropriately performing physical and / or chemical treatments on the cellulose fiber raw material within an appropriate range. 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, and by appropriately performing physical and / or chemical treatments on the cellulose fiber raw material within an appropriate range. In one embodiment, each of the Mw and Mw / Mn of the cellulose fiber raw material may be within the above range. In both the control of Mw and the control of Mw / Mn, examples of the above physical treatments include dry or wet grinding using microfrudizers, ball mills, disc mills, etc., and physical treatments that apply mechanical forces such as impact, shear, shear, and friction using grinders, homomixers, high-pressure homogenizers, ultrasonic devices, etc. Examples of the above chemical treatments include pulverization, bleaching, acid treatment, enzymatic treatment, and regenerative cellulose formation. In addition, accurate calculation of Mw, Mn, and Mw / Mn for chemically modified cellulose nanofibers may not be possible due to the presence of chemical modification groups. In such cases, the Mw, Mn, and Mw / Mn of the cellulose nanofiber immediately before chemical modification, or the cellulose fiber raw material (e.g., pulp) immediately before chemical modification, may be considered as the Mw, Mn, and Mw / Mn of the chemically modified cellulose nanofibers.

[0053] The weight-average molecular weight and number-average molecular weight of cellulose nanofibers referred to herein are values ​​obtained by dissolving cellulose nanofibers in N,N-dimethylacetamide to which lithium chloride has been added, and then determining them by gel permeation chromatography using N,N-dimethylacetamide as the solvent.

[0054] [Control of degree of polymerization 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 the depolymerization of amorphous cellulose inside the cellulose nanofibers, reducing the average degree of polymerization. At the same time, hydrolysis removes impurities such as hemicellulose and lignin in addition to the amorphous cellulose mentioned above, resulting in a porous structure inside the fibrous material.

[0055] The hydrolysis method is not particularly limited, but examples include acid hydrolysis, alkaline hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used individually or in combination of two or more. In the acid hydrolysis method, for example, α-cellulose obtained as pulp from fibrous plants is used as the cellulose fiber raw material, and while dispersed in an aqueous medium, an appropriate amount of protic acid, carboxylic acid, Lewis acid, heteropoly acid, etc. is added, and the average degree of polymerization can be easily controlled by heating while stirring. The reaction conditions such as temperature, pressure, and time vary depending on the cellulose species, cellulose concentration, acid species, acid concentration, etc., but are adjusted appropriately to achieve the desired average degree of polymerization. For example, one condition is to use an aqueous solution of mineral acid with a concentration of 2% by mass or less and treat the cellulose nanofibers at 100°C or higher under pressure for 10 minutes or more. Under these conditions, the catalytic component such as the acid penetrates into the cellulose nanofibers, promoting hydrolysis, reducing the amount of catalytic component used, and making subsequent purification easier. Furthermore, the dispersion of cellulose fiber raw materials during hydrolysis may contain a small amount of organic solvent in addition to water, as long as it does not impair the effects of the present invention.

[0056] [Alkali-soluble polysaccharides and acid-insoluble components] Between the microfibrils of cellulose nanofibers, and between the bundles of microfibrils, are present alkali-soluble polysaccharides such as hemicellulose and acid-insoluble components such as lignin. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and it plays a role in linking the microfibrils together by hydrogen bonding with cellulose. Lignin is a compound with an aromatic ring, and it is known to be covalently bonded with hemicellulose in the cell walls of plants.

[0057] The alkali-soluble polysaccharides that cellulose nanofibers may contain include not only hemicellulose but also β-cellulose and γ-cellulose. Alkali-soluble polysaccharides are understood by those skilled in the art to be components obtained as the alkali-soluble part of holocellulose obtained by solvent extraction and chlorine treatment of plants (e.g., wood) (i.e., components obtained by removing α-cellulose from holocellulose). Since alkali-soluble polysaccharides are polysaccharides containing hydroxyl groups and have poor heat resistance, they can cause problems such as decomposition when heated, yellowing during thermal aging, and a decrease in the strength of cellulose nanofibers. Therefore, it is preferable to have a low alkali-soluble polysaccharide content in cellulose nanofibers.

[0058] In one embodiment, the average content of alkali-soluble polysaccharides in 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, based on 100% by mass of cellulose nanofibers, from the viewpoint of maintaining the mechanical strength of cellulose nanofibers during melt kneading and suppressing yellowing. 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, from the viewpoint of ease of manufacturing cellulose nanofibers.

[0059] The average alkali-soluble polysaccharide content can be determined using the method described in non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000), by subtracting the α-cellulose content from the holocellulose content (Wise method). This method is understood in this industry as a method for measuring hemicellulose content. The alkali-soluble polysaccharide content is calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide content is taken as the average alkali-soluble polysaccharide content. However, the alkali-soluble polysaccharide content of chemically modified cellulose nanofibers may not be accurately calculated due to the presence of chemical modification groups. In this case, the average alkali-soluble polysaccharide content of the cellulose nanofiber immediately before chemical modification, or the cellulose fiber raw material (e.g., pulp) immediately before chemical modification, which is the raw material for the chemically modified cellulose nanofibers, may be considered as the average alkali-soluble polysaccharide content of the chemically modified cellulose nanofibers.

[0060] Acid-insoluble components that cellulose nanofibers may contain are understood by those skilled in the art as insoluble components remaining after sulfuric acid treatment of a degreased sample obtained by solvent extraction of plants (e.g., wood). Specifically, these acid-insoluble components are, but are not limited to, aromatic lignin. Acid-insoluble components are often colored themselves, which can impair the appearance of the resin composition and cause yellowing during thermal aging. Therefore, it is preferable to have a low average content of acid-insoluble components in cellulose nanofibers.

[0061] In one embodiment, the average content of acid-insoluble components in cellulose nanofibers is preferably 10% by mass or less, 5% by mass or less, or 3% by mass or less, based on 100% by mass of cellulose nanofibers, from the viewpoint of avoiding a decrease in the heat resistance of cellulose nanofibers and the resulting discoloration. The above content may be 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more, from the viewpoint of ease of manufacturing cellulose nanofibers.

[0062] The average acid-insoluble component content is determined using the Claesson method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000). This method is understood in this industry as a method for measuring lignin content. After stirring the sample in sulfuric acid solution to dissolve cellulose and hemicellulose, etc., the sample is filtered through glass fiber filter paper, and the resulting residue contains the acid-insoluble components. The acid-insoluble component content is calculated from the weight of these acid-insoluble components, and the number average of the acid-insoluble component content calculated for three samples is taken as the average acid-insoluble component content. However, the average acid-insoluble component content of chemically modified cellulose nanofibers may not be accurately calculated due to the presence of chemical modification groups. In this case, the average alkali-soluble polysaccharide content of the cellulose nanofiber immediately before chemical modification, or the cellulose fiber raw material (e.g., pulp) immediately before chemical modification, which is the raw material for the chemically modified cellulose nanofibers, may be considered as the average alkali-soluble polysaccharide content of the chemically modified cellulose nanofibers.

[0063] [Thermal decomposition onset temperature (T D )] The thermal decomposition onset temperature of cellulose nanofibers (T D In one embodiment, the thermal decomposition start temperature is 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, from the viewpoint of avoiding thermal degradation during melting and kneading and being able to exhibit mechanical strength. A higher thermal decomposition start temperature is preferable, but from the viewpoint of ease of manufacturing cellulose nanofibers, it may be, for example, 320°C or lower, or 310°C or lower, or 300°C or lower.

[0064] [Temperature at 1% weight loss (T 1% ), 250℃ weight loss rate (T 250℃ )] Temperature (T) when cellulose nanofibers lose 1 wt% of their weight. 1%In one embodiment, the temperature is preferably 260°C or higher, or 270°C or higher, or 275°C or higher, or 280°C or higher, or 285°C or higher, or 290°C or higher, from the viewpoint of avoiding thermal degradation during melting and kneading and being able to exhibit mechanical strength. 1% Higher temperatures are preferable, but from the viewpoint of ease of manufacturing cellulose nanofibers, temperatures of, for example, 330°C or lower, 320°C or lower, or 310°C or lower may also be acceptable.

[0065] Weight loss rate of cellulose nanofibers at 250°C (T 250℃ From the viewpoint of avoiding thermal degradation during melting and kneading and being able to exhibit mechanical strength, in one embodiment, it 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℃ While a lower concentration is preferable, from the viewpoint of ease of manufacturing cellulose nanofibers, it may be, for example, 0.1% or more, 0.5% or more, 0.7% or more, or 1.0% or more.

[0066] In this disclosure, T D This value is obtained from a graph in thermogravimetric (TG) analysis under nitrogen flow, where the x-axis is temperature and the y-axis is weight retention percentage. Cellulose nanofibers were 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, and then heated to 450°C at a heating rate of 10°C / min. The weight at 150°C (when moisture is almost completely removed) (weight loss of 0 wt%) was used as the starting point, and the temperature at which a 1 wt% weight loss occurred (T 1% ) and temperature (T) when weight decreases by 2 wt% 2% Obtain a straight line passing through ( ). The temperature at the point where this line intersects with the horizontal line (baseline) passing through the starting point of the weight loss of 0 wt% is T. D This is how it is defined.

[0067] 1% weight loss temperature (T 1% ) is the above T D This is the temperature at which the weight decreases by 1% by weight, starting from the weight at 150°C, when the temperature is continuously increased using this method.

[0068] Weight loss rate of cellulose nanofibers at 250°C (T 250℃ ) is the weight loss rate when cellulose nanofibers are held at 250°C under a nitrogen flow for 2 hours in TG analysis. 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 of reaching 250°C is taken as the starting point, and the weight after holding at 250°C for 2 hours is taken as W1, which is calculated using the following formula. Weight change rate at 250℃ (%): (W1-W0) / W0×100

[0069] [Porous Sheet] The properties of cellulose nanofibers (crystallinity, 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℃ Measurements of (etc.) can vary significantly depending on the form of the sample being measured. To ensure stable and reproducible measurements, a distortion-free porous sheet should be used as the measurement sample. The method for preparing the porous sheet is as follows.

[0070] First, a concentrated cake of cellulose nanofibers with a solid content of 10% by mass or more is added to tert-butanol, and then dispersed using a mixer or similar device until no aggregates remain. The concentration is adjusted to 0.5% by mass for every 0.5g of solid weight of cellulose nanofibers. 100g of the resulting tert-butanol dispersion is filtered on filter paper. Without removing the filtrate from the filter paper, it is sandwiched between two larger sheets of filter paper, and the edges of the larger sheets are pressed down with weights, and dried in a 150°C oven for 5 minutes. After that, the filter paper is peeled off to obtain a porous sheet with minimal distortion. The air permeability resistance R of this sheet is 10g / m² 2 Materials with a density of 100 sec / 100 ml or less are treated as porous sheets and used as measurement samples.

[0071] The air permeability resistance R was measured by measuring the basis weight W (g / m²) of a porous sheet sample that had been left standing for one day in an environment of 23°C and 50%RH. 2 After measuring the air permeability resistance (R) (sec / 100ml), the air permeability resistance is measured using a Wangyan-type air permeability resistance tester (for example, Asahi Seiko Co., Ltd., model EG01). At this time, 10g / m³ is used according to the following formula. 2 Calculate the value per unit area. Weight: 10g / m 2 Air permeability resistance (sec / 100ml) = R / W × 10

[0072] [Physical properties of cellulose nanofibers in resin compositions] Various physical properties of cellulose nanofibers in resin compositions (number-average fiber length, number-average fiber diameter, L / D ratio, degree of 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 following properties (including DS, DSs, DS heterogeneity ratio, coefficient of variation of DS heterogeneity ratio, etc., as described later) 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, and after thorough washing with the solvent, the solvent is replaced with tert-butanol. Subsequently, the cellulose nanofiber tert-butanol slurry is analyzed using the same measurement method as described above, and various physical properties of the cellulose nanofibers in the resin composition are calculated.

[0073] [Chemical modification] Cellulose nanofibers may be chemically modified cellulose nanofibers (also called chemically modified cellulose nanofibers). Cellulose nanofibers may be chemically modified beforehand, for example, at the cellulose fiber raw material stage, during the defibrillation process, or after the defibrillation process, or they may be chemically modified during or after the preparation of the slurry as a dispersion, or during or after the drying and granulation process.

[0074] As modifying agents for cellulose nanofibers, compounds that react with the hydroxyl groups of cellulose can be used, such as esterifying agents, etherifying agents, and silylating agents. In a preferred embodiment, the chemical modification is acylation using an esterifying agent, and particularly preferably acetylation. As esterifying agents, acid halides, acid anhydrides, vinyl carboxylates, and carboxylic acids are preferred.

[0075] The acid halide may be at least one compound selected from the group consisting of compounds represented by the following formula. R 1 -C(=O)-X (In the formula, R 1 (where X 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 these, acid chlorides are particularly suitable due to their reactivity and ease of handling. In the reaction of acid halides, one or more alkaline compounds may be added to act as a catalyst and to neutralize the acidic by-products. 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.

[0076] Any suitable acid anhydride can be used as the acid anhydride. 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 anhydrides such as benzoic acid and 4-methylbenzoic acid; Examples of dibasic carboxylic acid anhydrides include saturated aliphatic dicarboxylic anhydrides such as succinic anhydride and adipic acid, unsaturated aliphatic dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride, alicyclic dicarboxylic anhydrides such as 1-cyclohexene-1,2-dicarboxylic anhydride, hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride, and aromatic dicarboxylic anhydrides such as phthalic anhydride and naphthalic anhydride; Examples of polybasic carboxylic acid anhydrides with three or more bases include (anhydride) polycarboxylic acids such as trimellitic anhydride and pyromellitic anhydride. Furthermore, in the reaction of acid anhydrides, one or more acidic compounds such as sulfuric acid, hydrochloric acid, or phosphoric acid, or Lewis acids (for example, Lewis acid compounds represented as MYn, where M represents a metalloid 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 lanthanide element; n is an integer corresponding to the valence of M, representing 2 or 3; and Y represents a halogen atom, OAc, OCOCF3, ClO4, SbF6, PF6, or OSO2CF3(OTf)), or alkaline compounds such as triethylamine or pyridine may be added as catalysts.

[0077] Examples of vinyl carboxylates include those with the following formula: R-COO-CH=CH2 A vinyl carboxylate ester represented by the formula {wherein R is any 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, or an aryl group having 6 to 24 carbon atoms} is preferred. The vinyl carboxylate ester 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 octoate, divinyl adipate, vinyl methacrylate, vinyl crotate, vinyl octoate, vinyl benzoate, and vinyl cinnamate. In esterification reactions with vinyl carboxylates, 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 bicarbonates, primary to tertiary amines, quaternary ammonium salts, imidazoles and their derivatives, pyridines and their derivatives, and alkoxides may be added.

[0078] Examples of alkali metal hydroxides and alkaline earth metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and barium hydroxide. Examples of alkali metal carbonates, alkaline earth metal carbonates, and alkali metal bicarbonates include lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, and cesium bicarbonate.

[0079] Primary, secondary, and tertiary amines refer to primary, secondary, and tertiary amines, and specific examples 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.

[0080] Examples of imidazoles and their derivatives include 1-methylimidazole, 3-aminopropylimidazole, and carbonyldiimidazole.

[0081] Examples of pyridine and its derivatives include N,N-dimethyl-4-aminopyridine and picoline.

[0082] Examples of alkoxides include sodium methoxide, sodium ethoxide, and potassium t-butoxide.

[0083] The carboxylic acid is selected from the group consisting of compounds represented by the following formula. 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.)

[0084] Specific examples of carboxylic acids include at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, caproic acid, cyclohexanecarboxylic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, pivalic acid, methacrylic acid, crotonic acid, octic acid, benzoic acid, and cinnamic acid.

[0085] Among these carboxylic acids, at least one selected from the group consisting of acetic acid, propionic acid, and butyric acid, particularly acetic acid, is preferred from the viewpoint of reaction efficiency. Furthermore, in the reaction of carboxylic acids, one or more acidic compounds such as sulfuric acid, hydrochloric acid, or phosphoric acid, or Lewis acids (for example, Lewis acid compounds represented as MYn, where M represents a metalloid 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 lanthanide element; n is an integer corresponding to the valence of M, representing 2 or 3; and Y represents a halogen atom, OAc, OCOCF3, ClO4, SbF6, PF6, or OSO2CF3(OTf)), or alkaline compounds such as triethylamine or pyridine may be added as catalysts.

[0086] Among these esterification reagents, at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, vinyl acetate, vinyl propionate, vinyl butyrate, and acetic acid, with acetic anhydride and vinyl acetate being particularly preferred from the viewpoint of reaction efficiency.

[0087] [Degree of acyl substitution (DS)] When cellulose nanofibers are chemically modified (e.g., by hydrophobization such as acylation), they tend to have good dispersibility in resins. However, the cellulose nanofibers of this disclosure, especially when combined with a dispersant, easily exhibit good dispersibility in resins even when unsubstituted or with a low degree of substitution. When the cellulose nanofibers are esterified cellulose nanofibers, the degree of acyl substitution (DS) is preferably 0.1 or higher, or 0.2 or higher, or 0.25 or higher, or 0.3 or higher, or 0.5 or higher, in order to obtain esterified cellulose nanofibers with a high thermal decomposition onset temperature. Furthermore, since an unmodified cellulose skeleton remains in the esterified cellulose nanofibers, the degree of acyl substitution (DS) is preferably 2.0 or lower, or 1.8 or lower, or 1.5 or lower, or 1.2 or lower, or 1.0 or lower, or 0.8 or lower, or 0.7 or lower, or 0.6 or lower, or 0.5 or lower, in order to obtain esterified cellulose nanofibers that combine high tensile strength and dimensional stability derived from cellulose with a high thermal decomposition onset temperature derived from chemical modification.

[0088] The degree of acyl substitution (DS) of chemically modified cellulose nanofibers, when the modifying group is an acyl group, can be calculated from the reflected infrared absorption spectrum of esterified cellulose nanofibers based on the peak intensity ratio between the peak derived from the acyl group and the peak derived from the cellulose skeleton. The peak of the C=O absorption band based on the acyl group is at 1730 cm⁻¹. -1 The peak of the CO absorption band based on the cellulose backbone chain appears at 1030 cm⁻¹. -1 It appears there. The DS of esterified cellulose nanofibers is obtained by creating a correlation graph between the DS obtained from solid-state NMR measurements of esterified cellulose nanofibers (described later) and the modification rate (IR index 1030), which is defined as the ratio of the peak intensity of the absorption band of C=O based on the acyl group to the peak intensity of the absorption band of CO in the cellulose backbone chain, and a calibration curve calculated from the correlation graph. Degree of substitution DS = 4.13 × IR index (1030) This can be obtained by using [this method].

[0089] The method for calculating the DS of esterified cellulose nanofibers using solid-state NMR is described below for freeze-dried esterified cellulose nanofibers. 13 The following formula can be used to determine the signal intensity (Inf) from a single carbon atom derived from the modifying group, based on the total area intensity (Inp) of the signals attributed to carbon atoms C1-C6 derived from the pyranose ring of cellulose, which appear in the range of 50 ppm to 110 ppm. DS = (Inf) × 6 / (Inp) For example, if the modifying group is an acetyl group, you can use the 23 ppm signal assigned to -CH3. Use 13 The conditions for 13C solid-state NMR measurement are as follows, for example: Equipment:Bruker Biospin Avance500WB Frequency: 125.77MHz Measurement method: DD / MAS method Waiting time: 75 seconds NMR sample tube: 4mmφ Total number of times: 640 (approximately 14 hours) MAS: 14,500Hz Chemical shift reference: Glycine (External reference: 176.03 ppm)

[0090] The DS non-uniformity ratio (DSs / DSt), defined as the ratio of the degree of modification of the fiber surface (DSs) to the degree of modification of the entire fiber (DSt) (which is synonymous with the degree of acyl substitution (DS) above) of chemically modified cellulose nanofibers, is preferably 1.05 or higher. The larger the value of the DS non-uniformity ratio, the more pronounced the sheath-core-like non-uniform structure (i.e., a structure in which the fiber surface is highly chemically modified while the fiber center retains a structure close to the original unmodified cellulose), and while possessing high tensile strength and dimensional stability derived from cellulose, it is possible to improve the affinity with the resin when compounded with the resin, and improve the dimensional stability of the resin composition. The DS non-uniformity ratio is more preferably 1.1 or higher, or 1.2 or higher, or 1.3 or higher, or 1.5 or higher, or 2 or higher, and from the viewpoint of ease of manufacturing chemically modified cellulose nanofibers, it is preferably 30 or lower, or 20 or lower, or 10 or lower, or 6 or lower, or 4 or lower, or 3 or lower. 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 higher, more preferably 0.2 or higher, even more preferably 0.3 or higher, even more preferably 0.5 or higher, preferably 3.0 or lower, more preferably 2.5 or lower, particularly preferably 2.0 or lower, even more preferably 1.5 or lower, particularly preferably 1.2 or lower, and most preferably 1.0 or lower. The preferred range for DSt is as described above for acyl substituents (DS).

[0091] A smaller coefficient of variation (CV) of the DS heterogeneity ratio of chemically modified cellulose nanofibers is preferable because it reduces the variation in various physical properties of the resin composition. Preferably, the coefficient of variation is 50% or less, or 40% or less, or 30% or less, or 20% or less. The coefficient of variation can be further reduced in a method in which chemical modification is performed after defibrillation of the cellulose fiber raw material to obtain chemically modified cellulose nanofibers (i.e., sequential method), while it can be increased in a method in which defibrillation and chemical modification of the cellulose fiber raw material are performed simultaneously (i.e., simultaneous method). Although the mechanism of action is not clear, it is thought that in the simultaneous method, chemical modification proceeds more easily in the fine fibers generated in the initial stages of defibrillation, and as the hydrogen bonds between cellulose microfibrils decrease due to chemical modification, defibrillation proceeds further, resulting in an increase in the coefficient of variation of the DS heterogeneity ratio.

[0092] The coefficient of variation (CV) of the DS heterogeneity ratio can be calculated using the following formula: 100g of an aqueous dispersion of chemically modified cellulose nanofibers (solid content of 10% by mass or more) is taken, frozen and pulverized in 10g portions, and the DS heterogeneity ratio is calculated from the DSt and DSs of 10 samples. Then, the standard deviation (σ) and arithmetic mean (μ) of the DS heterogeneity ratios among the 10 samples are used. DS heterogeneity ratio = DSs / DSt Coefficient of variation (%) = Standard deviation σ / Arithmetic mean μ × 100

[0093] The method for calculating DSs is as follows: Esterified cellulose nanofibers, powdered by freeze-grinding, are placed on a 2.5 mmφ dish-shaped sample stage, the surface is pressed down to flatten it, and X-ray photoelectron spectroscopy (XPS) is performed. The XPS spectrum reflects the constituent elements and chemical bonding state of only the surface layer of the sample (typically a few nm). Peak separation is performed on the obtained C1s spectrum, and the area intensity (Ixp) of the peak attributed to a single carbon atom derived from the modifying group is used to determine the DSs using the following formula, compared to the area intensity (Ixf) of the peak attributed to a single carbon atom derived from the pyranose ring of cellulose (289 eV, CC bond). DSs = (Ixf) × 5 / (Ixp) For example, if the modifying group is an acetyl group, after separating the C1s spectrum at 285eV, 286eV, 288eV, and 289eV, the 289eV peak can be used for Ixp and the peak derived from the OC=O bond of the acetyl group (286eV) can be used for Ixf. The conditions used for XPS measurement are as follows, for example: Equipment used: ULVAC-FI VersaProbeII Excitation source: mono.AlKα 15kV × 3.33mA Analysis size: Approximately 200 μmφ Photoelectron extraction angle: 45° Capture area Narrow scan: C 1s, O 1s Pass Energy: 23.5 eV

[0094] The amount of cellulose nanofibers per 100 parts by mass of polyolefin resin (in one embodiment, unmodified polyolefin resin) in the resin composition is preferably 0.001 parts by mass or more, or 0.01 parts by mass or more, or 0.1 parts by mass or more, or 1 part by mass or more, from the viewpoint of balancing processability and mechanical properties, 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 parts by mass or less, from the viewpoint of stably achieving good dispersion of cellulose nanofibers in the resin composition.

[0095] The amount of cellulose nanofibers relative to 100% by mass of the resin composition is 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, from the viewpoint of balancing processability and mechanical properties, 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, from the viewpoint of stably achieving good dispersion of cellulose nanofibers in the resin composition.

[0096] <Polyolefin resins> In one embodiment, the resin composition includes a polyolefin resin. The polyolefin resin is a polymer obtained by polymerizing olefins (e.g., α-olefins) and / or alkenes as monomer units. Specific examples of polyolefin resins include ethylene-based (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-based (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.

[0097] From the viewpoint of obtaining good mechanical properties, particularly toughness, of the resin composition, and stably realizing the desired distribution state of cellulose nanofibers and the desired dispersed phase form of the polyamide resin, polypropylene resins are preferred.

[0098] The weight-average molecular weight of polyolefin resins, particularly polypropylene resins, is preferably 10,000 or more, or 15,000 or more, or 20,000 or more, from the viewpoint of obtaining good mechanical properties of the resin composition, especially toughness, and preferably 300,000 or less, or 200,000 or less, or 100,000 or less, from the viewpoint of stably achieving the desired distribution state of cellulose nanofibers and the desired dispersed phase form of polyamide resins.

[0099] The melt mass flow rate (MFR) of polyolefin resins, particularly polypropylene resins, measured in accordance with ISO 1133 at 230°C and a load of 21.2 N, is preferably 3 g / 10 min or more and 30 g / 10 min or less. The lower limit of the 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 the MFR does not exceed the upper limit, and from the viewpoint of the fluidity of the resin composition, it is desirable that it does not exceed the lower limit.

[0100] (Modified polyolefin resin) In one embodiment, the resin composition may include a modified polyolefin resin. In one embodiment, the resin composition includes a non-modified polyolefin resin and a modified polyolefin resin. The modified polyolefin resin can improve the dispersibility of cellulose nanofibers in the resin composition due to its good affinity with polyamide resins and / or cellulose nanofibers. From the viewpoint of affinity with polyamide resins and / or cellulose nanofibers, the modified polyolefin resin is preferably an acid-modified polyolefin resin. Mono- or polycarboxylic acids can be used as the acid for acid modification, and examples include maleic acid, fumaric acid, succinic acid, phthalic acid and their anhydrides, as well as citric acid. Maleic acid or its anhydride is particularly preferred due to its ease of increasing the modification rate. There are no particular restrictions on the modification method, but a common method is to heat the polyolefin resin above its melting point in the presence or absence of a peroxide and then melt-knead it. All of the aforementioned polyolefin resins can be used as the polyolefin resin to be acid-modified, but polypropylene resins are particularly preferred. In other words, in a particularly preferred embodiment, the modified polyolefin resin is an acid-modified polypropylene resin.

[0101] From the viewpoint of obtaining the advantages of using acid-modified polyolefin resins, the acid value is preferably 1 mg KOH / g or more, or 3 mg KOH / g or more, or 10 mg KOH / g or more, and from the viewpoint of maintaining good chemical stability of the resin composition, it is preferably 200 mg KOH / g or less, or 100 mg KOH / g or less, or 50 mg KOH / g or less.

[0102] The ratio of the carboxyl group concentration [COOH]MAH of the acid-modified polyolefin resin to the terminal amino group concentration [NH2] of the polyamide resin, [COOH]MAH / [NH2], is preferably greater than 0.1, 0.5 or more, or 1 or more, from the viewpoint of obtaining the advantages of using the acid-modified polyolefin resin, and preferably 300 or less, 150 or less, 100 or less, 50 or less, or 30 or less, from the viewpoint of maintaining good chemical stability of the resin composition.

[0103] The melt mass flow rate (MFR) of acid-modified polyolefin resins, particularly acid-modified polypropylene resins, measured at 230°C and under a load of 21.2 N in accordance with ISO 1133, is preferably 50 g / 10 min or more, or 100 g / 10 min or more, or 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 acid-modified polyolefin resin and cellulose nanofibers. There is no particular upper limit, but it is preferably 500 g / 10 min to maintain mechanical strength.

[0104] In one embodiment, the melting points of the unmodified polyolefin resin and the modified polyolefin resin are preferably 100°C or higher, or 140°C or higher, 150°C or higher, 160°C or higher, or 170°C or higher, from the viewpoint of good mechanical properties of the resin composition, and preferably 190°C or lower, or 180°C or lower, from the viewpoint of the availability of the polyolefin resin.

[0105] In one embodiment, the glass transition temperatures of the unmodified polyolefin resin and the modified polyolefin resin are preferably -50°C or higher, 0°C or higher, or 50°C or higher, from the viewpoint of good mechanical properties of the resin composition, and preferably 200°C or lower, 150°C or lower, or 100°C or lower, from the viewpoint of the availability of these polyolefin resins.

[0106] In this disclosure, the melting point refers to the peak top temperature of the endothermic peak that appears when the temperature is increased from 23°C at a heating rate of 10°C / min using a differential scanning calorimetry (DSC). If two or more endothermic peaks appear, the peak top temperature of the highest-temperature endothermic peak is referred to. The enthalpy of the endothermic peak at this time is preferably 10 J / g or more, and more preferably 20 J / g or more. When measuring, it is preferable to use a sample that has been heated to a temperature condition of melting point + 20°C or higher to melt the resin, and then cooled to 23°C at a cooling rate of 10°C / min. In this disclosure, the glass transition temperature refers to the peak top temperature of the peak where the storage modulus decreases significantly and the loss modulus is at its maximum when measured using a dynamic viscoelasticity analyzer while increasing the temperature from 23°C at a heating rate of 2°C / min at an applied frequency of 10 Hz. If two or more loss modulus peaks appear, the peak top temperature of the highest-temperature peak is referred to. To improve measurement accuracy, it is desirable to perform measurements at least once every 30 seconds. While there are no particular restrictions on the preparation method of the measurement samples, it is preferable to use cut pieces from hot-pressed products to eliminate the effects of molding distortion, and from the standpoint of heat conduction, the size (width and thickness) of the cut pieces should be as small as possible.

[0107] The amount of modified polyolefin resin per 100 parts by mass of unmodified polyolefin resin is preferably 0.1 parts by mass or more, or 0.5 parts by mass or more, or 1 part by mass or more, or 2 parts by mass or more, or 3 parts by mass or more, or 4 parts by mass or more, or 5 parts by mass or more, from the viewpoint of obtaining good interfacial strength between the thermoplastic resin and cellulose nanofibers in the resin composition, and preferably 50 parts by mass or less, or 45 parts by mass or less, or 40 parts by mass or less, or 35 parts by mass or less, or 30 parts by mass or less, or 20 parts by mass or less, from the viewpoint of obtaining good toughness of the resin composition due to the contribution of the unmodified polyolefin resin.

[0108] <Polyamide resin> Examples of polyamide resins include: polyamides obtained by polycondensation reactions 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., butanediamine, pentanediamine, hexanediamine, heptanediamine) Examples include polyamides obtained as copolymers with 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. (e.g., 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 obtained by copolymerizing these (e.g., polyamide 6,T / 6,I, etc.).

[0109] The polyamide resin preferably has an aromatic skeleton and an aliphatic skeleton. Among polyamide resins having an aromatic skeleton and an aliphatic skeleton, amorphous polyamide resins are more preferred. When a masterbatch of cellulose nanofibers and a polyamide resin is mixed with a polyolefin resin in the production of a resin composition, if the polyamide resin is amorphous, the polyamide resin will hold the cellulose nanofibers well even in the polyolefin resin, making it difficult for the cellulose nanofibers to detach from the masterbatch and migrate into the polyolefin resin. Cellulose nanofibers are difficult to finely disperse in polyolefin resins, and cellulose nanofibers that migrate into polyolefin resins tend to form aggregates and reduce the mechanical properties of the resin composition. Therefore, it is advantageous that the polyamide resin can suppress the migration of cellulose nanofibers into the polyolefin resin.

[0110] The polyamide resin having an aromatic skeleton and an aliphatic skeleton is preferably one or more selected from the group consisting of polyamide 6,T, polyamide 6,I, polyamide 9,T, polyamide 10,T, polyamide 2M5,T, and polyamide MXD, and is particularly preferably polyamide 6,I.

[0111] The glass transition temperature of the polyamide resin is preferably 60°C or higher, or 80°C or higher, or 100°C or higher, from the viewpoint of improving the heat resistance of the resin composition, and preferably 250°C or lower, or 200°C or lower, or 150°C or lower, from the viewpoint of ease of manufacturing the resin composition.

[0112] The difference Tg1-Tg2 between the glass transition temperature Tg1 of the polyamide resin and the glass transition temperature Tg2 of the polyolefin resin is preferably greater than 80°C, or 90°C or higher, or 100°C or higher, from the viewpoint of stably achieving the desired distribution state of cellulose nanofibers and the desired dispersed phase form of the polyamide resin, and preferably 250°C or lower, 200°C or lower, or 150°C or lower, from the viewpoint of obtaining a uniform resin composition.

[0113] From the viewpoint of improving the heat resistance of the resin composition, the melting point of the polyamide resin is preferably 220°C or higher, or 230°C or higher, or 240°C or higher, or 245°C or higher, and from the viewpoint of ease of manufacturing the resin composition, the above melting point is preferably 350°C or lower, or 320°C or lower, or 300°C or lower.

[0114] The terminal amino group concentration [NH2] of the polyamide resin is preferably 1 μmol / g or more, or 8 μmol / g or more, or 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.

[0115] The terminal carboxyl group concentration [COOH] of the polyamide resin is preferably 20 μmol / g or more, or 30 μmol / g or more, and preferably 500 μmol / g or less, or 300 μmol / g or less, or 150 μmol / g or less, or 100 μmol / g or less, or 80 μmol / g or less.

[0116] In polyamide resins, the ratio of carboxy-terminal groups to total terminal groups ([COOH] / [total terminal groups]) is preferably 0.30 or higher, or 0.35 or higher, or 0.40 or higher, or 0.45 or higher, from the viewpoint of dispersibility of cellulose nanofibers in the resin composition, and preferably 0.99 or lower, or 0.95 or lower, or 0.90 or lower, or 0.85 or lower, or 0.80 or lower, from the viewpoint of the color tone of the resin composition.

[0117] The end group concentration of polyamide resins can be adjusted by known methods. One adjustment method involves adding an end group adjusting agent (e.g., diamine compounds, monoamine compounds, dicarboxylic acid compounds, monocarboxylic acid compounds, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, etc.) to the polymerization solution during the polymerization of polyamide so that a predetermined end group concentration is achieved.

[0118] Examples of end modifiers that react with terminal amino groups 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 several of these arbitrarily selected. Among these, from the viewpoint of reactivity, stability of the encapsulated end, and cost, one or more end modifiers 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, with acetic acid being the most preferred.

[0119] Examples of end modifiers that react with terminal carboxyl groups include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine, and any mixture thereof. Among these, one or more end modifiers 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 sealing end, and cost.

[0120] The concentrations of amino-terminated and carboxy-terminated groups in polyamide resins are: 1 The characteristic signal can be determined from the integrated value of the characteristic signal corresponding to each terminal group by 1H-NMR. This method is preferred in terms of accuracy and simplicity. More specifically, it is recommended to use the method described in Japanese Patent Publication No. 7-228775, using deuterated trifluoroacetic acid as the measurement solvent and performing 300 or more scans for integration.

[0121] The weight-average molecular weight of the polyamide resin is preferably 1,000 or more, or 5,000 or more, or 10,000 or more, from the viewpoint of obtaining good heat resistance and mechanical properties of the resin composition, and preferably 100,000 or less, or 50,000 or less, or 20,000 or less, from the viewpoint of ease of manufacturing the polyamide resin. The weight-average molecular weight is a value obtained using gel permeation chromatography and converted to standard polymethyl methacrylate.

[0122] The intrinsic viscosity [η] of polyamide resins, measured under conditions of 30°C in concentrated sulfuric acid, is preferably 0.6 to 2.0 dL / g, 0.7 to 1.4 dL / g, 0.7 to 1.2 dL / g, or 0.7 to 1.0 dL / g, from the viewpoint of good in-mold fluidity and good appearance of molded pieces when the resin composition is, for example, injection molded. In this disclosure, "intrinsic viscosity" is synonymous with viscosity generally called intrinsic viscosity. The intrinsic viscosity is determined by measuring the ηsp / c of ​​several measurement solvents of different concentrations under conditions of 30°C in 96% concentrated sulfuric acid, deriving a relationship between each ηsp / c and concentration (c), and extrapolating the concentration to zero. This extrapolated value is the intrinsic viscosity. Details of the above method are described, for example, on pages 291 to 294 of Polymer Process Engineering (Prentice-Hall, Inc. 1994). From an accuracy standpoint, it is desirable to use at least four different concentrations of the measurement solvents (e.g., 0.05 g / dL, 0.1 g / dL, 0.2 g / dL, and 0.4 g / dL) for the measurements.

[0123] The amount of polyamide resin per 100 parts by mass of polyolefin resin (in one embodiment, unmodified polyolefin resin) in the resin composition is, from the viewpoint of imparting good heat resistance and mechanical properties to the resin composition by the presence of the polyamide resin, 0.1 parts by mass or more, 1 part by mass or more, 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more in one embodiment, and from the viewpoint of easily forming a desired dispersed phase form of the polyamide resin, 50 parts by mass or less, 45 parts by mass or less, or 40 parts by mass or less in one embodiment.

[0124] <Other thermoplastic resins> In one embodiment, the resin composition may contain one or more thermoplastic resins other than polyolefin resins and polyamide resins, such as polyester resins, polyacetal resins, polyphenylene ether resins, and polyphenylene sulfide resins. In one embodiment, these thermoplastic resins may have a melting point of 100°C to 350°C or a glass transition temperature of 100°C to 250°C. From the viewpoint of improving the heat resistance of the resin composition, in one embodiment, the melting point may be 100°C or higher, or 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, and from the viewpoint of ease of manufacturing the resin composition, in one embodiment, it may be 350°C or lower, or 320°C or lower.

[0125] As the polyester 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 these, PET, PBS, PBSA, PBT, and PEN are more preferred, and PBS, PBSA, and PBT are particularly preferred.

[0126] The end groups of the polyester resin can be arbitrarily changed by the monomer ratio during polymerization, the presence or absence and amount of end stabilizers added, etc. The ratio of carboxyl end groups to the total end groups of the polyester resin ([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 the dispersibility of cellulose nanofibers in the resin composition, and 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.

[0127] Common polyacetal resins include homopolyacetals made from formaldehyde and copolyacetals with trioxane as the main monomer and 1,3-dioxolane as a comonomer component. Both are usable, but copolyacetals are preferred from the viewpoint of thermal stability during processing. The amount of structure derived from the comonomer component (e.g., 1,3-dioxolane) is preferably 0.01 mol% or more, 0.05 mol% or more, 0.1 mol% or more, or 0.2 mol% or more from the viewpoint of thermal stability during extrusion and molding processes, and preferably 4.0 mol% or less, 3.5 mol% or less, 3.0 mol% or less, 2.5 mol% or less, or 2.3 mol% or less from the viewpoint of mechanical strength.

[0128] <Additional ingredients> The resin composition may further contain additional components as needed to improve its performance. Examples of additional components include filler components other than cellulose nanofibers; dispersants; plasticizers; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as zeolites, ceramics, talc, silica, metal oxides, and metal powders; colorants; fragrances; pigments; flow regulators; leveling agents; conductive agents; heat stabilizers; antioxidants; antistatic agents; UV absorbers; UV 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, but may be, for example, 0.01 to 50% by mass, or 0.1 to 30% by mass.

[0129] [Dispersant] The dispersant contributes to improving the dispersibility of cellulose nanofibers in the resin composition. Examples of dispersants include liquid rubber and compounds having hydrophilic and hydrophobic parts (hereinafter also referred to as amphiphilic molecules). The amount of dispersant per 100 parts by mass of polyolefin resin (in one embodiment, unmodified polyolefin resin) may be 0.001 parts by mass or more, or 0.1 parts by mass or more, in one embodiment, or 100 parts by mass or less, or 50 parts by mass or less, or 30 parts by mass or less.

[0130] (Liquid rubber) In this disclosure, "liquid rubber" means a substance that is fluid at 23°C and forms a rubber elastic body by crosslinking (more specifically, vulcanization) and / or chain extension. In one embodiment, the liquid rubber is an uncured material. Furthermore, "fluid" means that, in one embodiment, liquid rubber dissolved in cyclohexane is placed in a vial with a diameter of 21 mm and a total length of 50 mm at 23°C and dried, so that the liquid rubber fills the vial to a height of 1 mm, is sealed, and when the vial is left upside down for 24 hours, a movement of 0.1 mm or more of the substance in the height direction can be observed.

[0131] Liquid rubber can function as a dispersant for effectively dispersing cellulose nanofibers in thermoplastic resins, and tends to exhibit superior ability to suppress cellulose nanofiber aggregation and heat resistance compared to, for example, liquid non-rubber materials. When such liquid rubber is used, heating and kneading can be carried out sufficiently during the production of the resin composition without concern for thermal degradation of each component, thus enabling good dispersion of cellulose nanofibers in the thermoplastic resin. Molded articles formed from resin compositions produced in this way have excellent mechanical properties and can also possess excellent decorative properties and aesthetic appeal due to their high surface smoothness.

[0132] The liquid rubber may have the monomer composition of a general rubber, and is preferably relatively low in molecular weight from the viewpoint of ease of handling and good dispersibility of cellulose nanofibers. In one embodiment, the liquid rubber exhibits a liquid form due to having a number-average molecular weight (Mn) of 80,000 or less. Unless otherwise specified, the number-average molecular weight and weight-average molecular weight of the various rubbers in this disclosure are values ​​obtained in terms of standard polystyrene using gel permeation chromatography with chloroform as the solvent and a measurement temperature of 40°C.

[0133] In one embodiment, liquid rubber may be combined with cellulose nanofibers to form a masterbatch, and such a masterbatch may be further combined with a polyamide resin to form another masterbatch.

[0134] The number-average molecular weight (Mn) of the liquid rubber 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. It 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 liquid rubber.

[0135] The weight-average molecular weight (Mw) of the liquid rubber 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. It 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 liquid rubber.

[0136] The ratio (Mw / Mn) of the number-average molecular weight (Mn) to the weight-average molecular weight (Mw) of the liquid rubber is preferably 1.5 or higher, or 1.8 or higher, or 2 or higher, in that the molecular weight variation allows for a high degree of compatibility of multiple properties (in one embodiment, a high degree of compatibility between good dispersion of cellulose nanofibers in the resin and a good flexural modulus of the resin composition). In that the molecular weight variation is not excessively large and the desired physical properties of the resin composition can be obtained stably, for example, in terms of compatibility between fluidity and impact resistance, it is preferably 10 or lower, or 8 or lower, or 5 or lower, or 3 or lower, or 2.7 or lower.

[0137] Liquid rubber can have good thermal stability. The thermal decomposition onset temperature of liquid rubber (T D In terms of good thermal stability, the temperature at which thermal decomposition begins is, in one embodiment, 200°C or higher, 250°C or higher, or 300°C or higher. A higher thermal decomposition onset temperature is preferable, but from the viewpoint of the availability of liquid rubber, in one embodiment it may be 500°C or lower, 450°C or lower, or 400°C or lower.

[0138] The glass transition temperature of liquid rubber is preferably -150°C or higher, or -120°C or higher, or -100°C or higher, in terms of good thermal stability, and preferably 25°C or lower, or 10°C or lower, or 0°C or lower, in terms of good fluidity.

[0139] In one embodiment, the liquid rubber comprises a diene rubber, and in another embodiment, a conjugated diene polymer or a non-conjugated diene polymer or a hydrogenated version thereof. The polymer or its hydrogenated version may be an oligomer. The monomers constituting the liquid rubber may be unmodified or modified (e.g., acid-modified, hydroxyl-modified, etc.). In one embodiment, the liquid rubber may have reactive groups at both ends (e.g., one or more selected from the group consisting of hydroxyl groups, carboxyl groups, isocyanate groups, thio groups, amino groups, and halo groups), and therefore may be bifunctional. These reactive groups contribute to crosslinking and / or chain extension of the liquid rubber.

[0140] Conjugated diene polymers The conjugated diene polymer may be a homopolymer, or a copolymer of two or more conjugated diene monomers, or a copolymer of a conjugated diene monomer and another monomer. The copolymer may be random or block-shaped.

[0141] Examples of 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 individually or in combination of two or more.

[0142] 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 a conjugated diene monomer. Examples include styrene, m or p-methylstyrene, α-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, diphenylethylene, and divinylbenzene, which may be used individually or in combination of two or more. From the viewpoint of moldability of the resin composition and impact resistance of the molded article, styrene is preferred.

[0143] Examples of random copolymers include butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and butadiene-isoprene-styrene random copolymers. Regarding the compositional distribution of each monomer in the copolymer chain, examples include perfectly random copolymers with a composition close to statistically random, and tapered random copolymers with a gradient in the compositional distribution. The bonding mode of the conjugated diene polymer, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or different between molecules.

[0144] A block copolymer may be a copolymer consisting of two or more blocks. For example, a block copolymer may have a structure such as AB, ABA, or ABAB, where block A is an aromatic vinyl monomer and block B is a block of conjugated diene monomer and / or a copolymer of aromatic vinyl monomer and conjugated diene monomer. The boundaries between each block do not necessarily need to be clearly distinguishable; for example, if block B is a copolymer of aromatic vinyl monomer and conjugated diene monomer, the aromatic vinyl monomer in block B may be distributed uniformly or tapered. Furthermore, block B may have multiple portions where the aromatic vinyl monomer is uniformly distributed and / or tapered. In addition, block B may have multiple segments with different aromatic vinyl monomer content. When multiple blocks A and block B exist in the copolymer, their molecular weights and compositions may be the same or different.

[0145] The block copolymer may be a mixture of two or more types in which one or more of the following are different: bond type, molecular weight, aromatic vinyl compound species, conjugated diene compound species, 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.

[0146] In conjugated diene polymers, the amount of vinyl bonds in the conjugated diene bond units (e.g., 1,2- or 3,4- bonds of butadiene) 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 a conjugated diene bond unit (e.g., the amount of 1,2-bonds in butadiene) is, 13 This can be determined by 13C-NMR (quantitative mode). That is, 13 In 1C-NMR, integrating the peak areas shown below yields a value proportional to the carbon content of each structural unit, which can then be converted to the mass percentage of each structural unit. Styrene 145-147 ppm Vinyl 110-116 ppm Diene (cis) 24-28 ppm Diene (trans) 29-33 ppm

[0147] In a copolymer of a conjugated diene monomer and an aromatic vinyl monomer, the amount of aromatic vinyl monomer bonded to the conjugated diene monomer (hereinafter also referred to as the amount of aromatic vinyl bonded) may be preferably 5 mol% to 70 mol%, or 10 mol% to 50 mol%, based on 100% of the total moles of the conjugated diene polymer.

[0148] Examples of hydrogenated conjugated diene polymers include those exemplified above, such as hydrogenated butadiene homopolymers, isoprene homopolymers, styrene-butadiene copolymers, and acrylonitrile-butadiene copolymers.

[0149] In a preferred embodiment, the liquid rubber is one or more selected from the group consisting of polybutadiene, butadiene-styrene copolymer, polyisoprene, and polychloroprene. These may be derivatives (e.g., maleic anhydride modified, methacrylic acid modified, terminal hydroxyl group modified, hydrogenated, and combinations thereof).

[0150] Non-conjugated diene polymers The non-conjugated diene polymer may be a homopolymer, or a copolymer of two or more non-conjugated diene monomers, or a copolymer of a non-conjugated diene monomer and another monomer. The copolymer may be random or block. Examples of non-conjugated diene polymers include: Olefin polymers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, and ethylene-α-olefin copolymers. Examples include butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylic acid ester-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0151] In ethylene-α-olefin copolymers, monomers that can copolymerize with ethylene units include 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, aliphatic substituted vinyl monomers such as isobutylene, and styrene. Examples include aromatic vinyl monomers such as substituted styrene, vinyl acetate, acrylic acid esters, methacrylic acid esters, glycidyl acrylic acid esters, glycidyl methacrylic acid esters, hydroxyethyl methacrylic acid 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.

[0152] 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.

[0153] From the viewpoint of exhibiting 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 measured by a gel permeation chromatography analyzer using 1,2,4-trichlorobenzene as a solvent at 140°C with a polystyrene standard.

[0154] Furthermore, from the viewpoint of ease of handling during processing, the ethylene unit content of the ethylene-α-olefin copolymer is preferably 30 to 95% by mass relative to the total amount of the ethylene-α-olefin copolymer.

[0155] Ethylene-α-olefin copolymers can be produced by conventionally known manufacturing methods, such as those described in Japanese Patent Publication No. 4-12283, Japanese Unexamined Patent Publication No. 60-35006, Japanese Unexamined Patent Publication No. 60-35007, Japanese Unexamined Patent Publication No. 60-35008, Japanese Unexamined Patent Publication No. 5-155930, Japanese Unexamined Patent Publication No. 3-163088, and U.S. Patent No. 5,272,236.

[0156] In one embodiment, the liquid rubber comprises one or more selected from the group consisting of diene rubber, silicone rubber, urethane rubber, and polysulfide rubber, as well as hydrogenated versions thereof.

[0157] The viscosity of the liquid rubber 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 cellulose nanofibers in the liquid rubber, and preferably 100 mPa·s or more, or 300 mPa·s or more, or 500 mPa·s or more, from the viewpoint of thermal stability, effect of improving the dispersibility of cellulose nanofibers in the resin, and mechanical properties of the resin composition.

[0158] The viscosity of the liquid rubber 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 viewpoint of good dispersion of cellulose nanofibers in the liquid rubber and good dispersion of cellulose nanofibers in the resin by heating and kneading, and preferably 50 mPa·s or more, or 100 mPa·s or more, or 300 mPa·s or more, from the viewpoint of thermal stability, effect of improving the dispersibility of cellulose nanofibers in the resin, and mechanical properties of the resin composition.

[0159] The viscosity of the liquid rubber 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 cellulose nanofibers in the liquid rubber, and preferably 200 mPa·s or more, or 600 mPa·s or more, or 1,000 mPa·s or more, from the viewpoint of thermal stability, effect on improving the dispersibility of cellulose nanofibers in the resin, and mechanical properties of the resin composition.

[0160] The low temperature dependence of the viscosity of the liquid rubber is preferable because it allows for good dispersion of cellulose nanofibers in the liquid rubber over a wide mixing temperature range. From this viewpoint, it is particularly preferable that the viscosity of the liquid rubber at 80°C, 25°C, and 0°C is within the above range.

[0161] The viscosity of liquid rubber is measured using a Type B viscometer at a rotation speed of 10 rpm.

[0162] Liquid rubber may be combined with cellulose nanofibers to form a masterbatch. In the masterbatch, the mass ratio of cellulose nanofibers to liquid rubber 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.

[0163] The masterbatch containing cellulose nanofibers and liquid rubber may or may not contain additional components. Examples of additional components include one or more of the thermoplastic resins exemplified in this disclosure that may be included in the resin composition of this embodiment. The content of the additional components in the masterbatch may be, for example, 0.01 to 50% by mass, or 0.1 to 30% by mass.

[0164] In the resin composition, the amount of liquid rubber per 100 parts by mass of polyolefin resin (in one embodiment, unmodified polyolefin resin) is preferably 0.001 parts by mass or more, or 0.01 parts by mass or more, or 0.1 parts by mass or more, or 1 part by mass or more, 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.

[0165] In the resin composition, the content of cellulose nanofibers relative to 100% by mass of the total of cellulose nanofibers and liquid rubber is preferably 0.5% by mass or more, or 1% by mass or more, or 3% by mass or more, from the viewpoint of obtaining a good reinforcing effect from cellulose nanofibers, and preferably 80% by mass or less, or 60% by mass or less, or 33% by mass or less, or 30% by mass or less, or 20% by mass or less, or 10% by mass or less, from the viewpoint of obtaining the advantages of using liquid rubber.

[0166] The thermal decomposition initiation temperature T1 for liquid rubber, the thermal decomposition initiation temperature T2 for cellulose nanofibers, and the temperature T3 which is the melting point of polyolefin resin or the glass transition temperature + 70°C of polyamide resin, preferably have the following relationship in terms of good mechanical properties, decorative properties, and appearance of the resin composition and molded article: (T1)≧(T2)>(T3) The following conditions are met. T3 is the melting point if the resin is a crystalline resin, and the glass transition temperature + 70°C if it is an amorphous resin.

[0167] In one embodiment, the difference T1-T2 between T1 and T2 is preferably 5°C or higher, or 10°C or higher, or 30°C or higher, from the viewpoint of avoiding process constraints caused by the use of liquid rubber because liquid rubber is less susceptible to thermal degradation than cellulose nanofibers, and preferably 200°C or lower, or 150°C or lower, or 100°C or lower, from the viewpoint of the availability of liquid rubber.

[0168] In one embodiment, the difference T1-T3 between T1 and T3 is preferably 30°C or higher, or 50°C or higher, or 70°C or higher, from the viewpoint of avoiding thermal degradation of the liquid rubber due to heating during the manufacture and processing of the resin composition and improving the mechanical properties, decorative properties, and appearance of the resin composition and the molded article formed therefrom, and preferably 200°C or lower, or 150°C or lower, or 100°C or lower, from the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article.

[0169] In one embodiment, the difference T2-T3 between T2 and T3 is preferably 30°C or higher, or 50°C or higher, or 70°C or higher, from the viewpoint of avoiding thermal degradation of cellulose nanofibers due to heating during the manufacture and processing of the resin composition and improving the mechanical properties, decorative properties, and appearance of the resin composition and the molded article formed therefrom. From the viewpoint of easily selecting a resin that imparts good mechanical properties to the resin composition and the molded article, it is preferably 200°C or lower, or 150°C or lower, or 100°C or lower.

[0170] (Amphiphilic molecules) Examples of amphiphilic molecules include polymers (including oligomers) having hydrophilic and hydrophobic segments. From the viewpoint of suppressing aggregation of cellulose nanofibers, amphiphilic molecules are preferably water-soluble polymers. In this disclosure, "water-soluble" means dissolving 0.1 g or more in 100 g of water at 23°C. Examples of amphiphilic molecules include those having a carbon atom as a basic skeleton and functional groups composed of elements selected from carbon, hydrogen, oxygen, nitrogen, chlorine, sulfur, and phosphorus. As long as the molecule has the above structure, those in which an inorganic compound and the above functional groups are chemically bonded are also preferred. The hydrophilic segment has good affinity with the surface of cellulose nanofibers, and the hydrophobic segment suppresses aggregation of cellulose fibers through the hydrophilic segment and is also easily compatible with resins. Therefore, amphiphilic molecules in which both hydrophilic and hydrophobic segments exist within the same molecule are preferred.

[0171] The HLB value of the amphiphilic molecule is preferably 0.1 or more and less than 15. The HLB value is a value that indicates the balance between hydrophobicity and hydrophilicity of a surfactant, and takes a value from 1 to 20, with a smaller number indicating stronger hydrophobicity and a larger number indicating stronger hydrophilicity. In this disclosure, the HLB value is a value obtained by the following Griffin method formula. In the formula below, "sum of formula weights of hydrophilic groups / molecular weight" is the mass % of the hydrophilic groups. Equation 1) Griffin method: HLB value = 20 × (sum of formula weights of hydrophilic groups / molecular weight)

[0172] The lower limit of the HLB value for amphiphilic molecules is preferably 0.1, more preferably 0.2, and most preferably 1, from the viewpoint of easy solubility in water. The upper limit of the HLB value is preferably less than 15, more preferably 10, more preferably 8, and most preferably 7, from the viewpoint of the dispersibility of cellulose nanofibers in resin.

[0173] In a typical embodiment, the hydrophilic segment is a portion that exhibits good affinity with cellulose nanofibers by containing a hydrophilic structure (e.g., one or more hydrophilic groups selected from hydroxyl groups, carboxyl groups, carbonyl groups, amino groups, ammonium groups, amide groups, sulfo groups, etc.). Examples of hydrophilic segments include polyethylene glycol segments (i.e., segments of multiple oxyethylene units) (PEG blocks), segments containing repeating units including quaternary ammonium salt structures, polyvinyl alcohol segments, polyvinylpyrrolidone segments, polyacrylic acid segments, carboxyvinyl polymer segments, cationized guar gum segments, hydroxyethylcellulose segments, methylcellulose segments, carboxymethylcellulose segments, polyurethane soft segments (specifically diol segments), and the like. In a preferred embodiment, the hydrophilic segment contains oxyethylene units.

[0174] Examples of hydrophobic segments include segments having alkylene oxide units with 3 or more carbon atoms (e.g., PPG blocks), and segments containing the following polymer structures: Acrylic polymers, styrene resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, polyhexamethylene adipamide (6,6 nylon), polyhexamethylene azeramide (6,9 nylon), polyhexamethylene sevacamide (6,10 nylon), polyhexamethylene dodecanoamide (6,12 nylon), polybis(4-aminocyclohexyl)methanedodecane, etc., polycondensates of C4-C12 organic dicarboxylic acids and C2-C13 organic diamines, polycondensates of ω-amino acids (e.g., ω-aminoundecanoic acid) (e.g., polyundecanoamide (1) Amino acid lactams containing ring-opened polymers of lactams, such as nylon 1, polycapramid (nylon 6), which is a ring-opened polymer of ε-aminocaprolactam, and polylauric lactam (nylon 12), which is a ring-opened polymer of ε-aminolaurolactam; polymers composed of diamines and dicarboxylic acids; polyacetal resins; polycarbonate resins; polyester resins; polyphenylene sulfide resins; polysulfone resins; polyetherketone resins; polyimide resins; fluorine resins; hydrophobic silicone resins; melamine resins; epoxy resins; and phenolic resins.

[0175] In a preferred embodiment, the amphiphilic molecule has a PEG block as a hydrophilic group and a PPG block as a hydrophobic group within the molecule.

[0176] Amphiphilic molecules may have graft copolymer structures and / or block copolymer structures. These structures may be single or in combination of two or more. In the case of two or more structures, they may form polymer alloys. Furthermore, these copolymers may be partially modified or terminally modified (acid-modified).

[0177] The structure of amphiphilic molecules is not particularly limited, but when the hydrophilic segment is A and the hydrophobic segment is B, examples include AB-type block copolymers, ABA-type block copolymers, BAB-type block copolymers, ABAB-type block copolymers, ABABA-type block copolymers, BABAB-type copolymers, tribranched copolymers containing A and B, tetrabranched copolymers containing A and B, star-shaped copolymers containing A and B, monocyclic copolymers containing A and B, polycyclic copolymers containing A and B, and cage-shaped copolymers containing A and B.

[0178] The structure of the amphiphilic molecule is preferably an AB-type block copolymer, an ABA-type triblock copolymer, a tribranched copolymer containing A and B, or a tetrabranched copolymer containing A and B, and more preferably an ABA-type triblock copolymer, a tribranched structure (i.e., a tribranched copolymer containing A and B), or a tetrabranched structure (i.e., a tetrabranched copolymer containing A and B). In order to ensure good affinity with cellulose nanofibers, it is desirable that the structure of the amphiphilic molecule be one of the above structures.

[0179] Suitable examples of amphiphilic molecules include copolymers obtained by using one or more compounds that provide a hydrophilic segment (e.g., polyethylene glycol) and compounds that provide a hydrophobic segment (e.g., polypropylene glycol, poly(tetramethylene ether) glycol (PTMEG), polybutadienediol, etc.) (e.g., block copolymers of propylene oxide and ethylene oxide, block copolymers of tetrahydrofuran and ethylene oxide). Amphiphilic molecules may be used alone or in combination of two or more. When two or more are used in combination, they may be used as a polymer alloy. Modified copolymers of the above-mentioned copolymers (e.g., those modified with at least one compound selected from unsaturated carboxylic acids, their acid anhydrides, or their derivatives) can also be used.

[0180] Among these, copolymers of polyethylene glycol and polypropylene glycol, copolymers of polyethylene glycol and poly(tetramethylene ether) glycol (PTMEG), and mixtures thereof are preferred from the viewpoint of heat resistance (odor resistance) and mechanical properties, with copolymers of polyethylene glycol and polypropylene glycol being more preferred from the viewpoint of handling and cost.

[0181] In a typical embodiment, amphiphilic molecules have a cloud point. When the temperature of an aqueous solution of a nonionic surfactant having a polyether chain, such as a polyoxyethylene chain, as the hydrophilic portion is increased, the previously transparent or translucent aqueous solution becomes cloudy at a certain temperature (this temperature is called the cloud point). That is, when an aqueous solution that is transparent or translucent at low temperatures is heated, the solubility of the nonionic surfactant decreases sharply at a certain temperature, and the surfactants that were previously dissolved aggregate and become cloudy, separating from the water. This is thought to be because at high temperatures, the nonionic surfactant loses its hydration ability (the hydrogen bonds between the polyether chain and water break, and the solubility in water decreases sharply). The cloud point tends to be lower the longer the polyether chain. Since it dissolves in water in any proportion below the cloud point, the cloud point serves as a measure of hydrophilicity in amphiphilic molecules.

[0182] The cloud point of amphiphilic molecules can be measured by the following method: Using a tuning fork vibrating viscometer (e.g., SV-10A manufactured by A&D Co., Ltd.), aqueous solutions of amphiphilic molecules are prepared at 0.5% by mass, 1.0% by mass, and 5% by mass, and measurements are taken at temperatures ranging from 0 to 100°C. At this time, the point at which an inflection occurs (a change in viscosity or the point at which the aqueous solution becomes cloudy) is observed at each concentration is defined as the cloud point.

[0183] From the viewpoint of handling ease, the lower limit of the cloud point of the amphiphilic molecule is preferably 0°C, more preferably 10°C, and most preferably 20°C. The upper limit of the cloud point is not particularly limited, but is preferably 120°C, more preferably 110°C, even more preferably 100°C, and most preferably 60°C. In order to ensure good affinity with cellulose nanofibers, it is desirable that the cloud point of the amphiphilic molecule be within the above range.

[0184] Amphiphilic molecules with a solubility parameter (SP value) of 7.25 or higher are more preferable. Having an SP value within this range improves the dispersibility of cellulose nanofibers in the resin.

[0185] According to Foders' literature (RF Foders: Polymer Engineering & SCienCe, vol.12(10), p.2359-2370 (1974)), the SP value depends on both the cohesive energy density and molar molecular weight of the substance, and these are thought to depend on the type and number of substituents in the substance. According to Ueda et al.'s literature (Paint Research, No.152, Oct.2010), the SP values ​​(Cal / Cm) for major existing solvents are... 3 ) 1 / 2 It has been made public.

[0186] The SP value of an amphiphilic molecule can be experimentally determined from the boundary between solubility and insolubility when the amphiphilic molecule is dissolved in various solvents with known SP values. For example, it can be determined by whether the entire volume dissolves when 1 mL of an amphiphilic molecule is dissolved in various solvents (10 mL) with different SP values ​​at room temperature under stirring for 1 hour. For instance, if an amphiphilic molecule is soluble in diethyl ether, its SP value will be 7.25 or higher.

[0187] As amphiphilic molecules, those that do not exhibit a boiling point or have a boiling point higher than that of water are preferred. It is advantageous from the viewpoint of finely dispersing cellulose nanofibers in the resin during melt kneading if one or more thermoplastic resins contained in the resin composition have a boiling point higher than that of all of them. Note that a boiling point higher than that of water refers to a boiling point higher than the boiling point at each pressure on the vapor pressure curve of water (for example, 100°C at 1 atmosphere).

[0188] By selecting amphiphilic molecules with a higher boiling point than water, for example, in the process of obtaining a dried cellulose nanofiber by drying a slurry containing water as a liquid medium in the presence of amphiphilic molecules, the aggregation of cellulose nanofibers can be significantly suppressed by replacing water with amphiphilic molecules during the evaporation process, thereby creating amphiphilic molecules on the surface of the cellulose nanofibers.

[0189] The boiling point of an amphiphilic molecule at 1 atmosphere may, in one embodiment, be greater than 100°C, or 150°C or higher, or 200°C or higher, and in one embodiment, it may be 350°C or lower, or 300°C or lower.

[0190] The melting point of the amphiphilic molecules may be 80°C or below, or 70°C or below, and may be -100°C or above, or -50°C or above, in order to allow the amphiphilic molecules to more uniformly coat the cellulose nanofibers and to more finely disperse the cellulose nanofibers in the resin. The number-average molecular weight of the amphiphilic molecules may be 1,000 or above, or 2,000 or above, and may be 50,000 or below, or 20,000 or below, in order to allow the amphiphilic molecules to more uniformly coat the cellulose nanofibers and to more finely disperse the cellulose nanofibers in the resin. The number-average molecular weight of the amphiphilic molecules is a value obtained using gel permeation chromatography on a standard polystyrene basis.

[0191] From the viewpoint of finely dispersing the cellulose nanofibers in the resin composition, the amount of amphiphilic molecules is preferably 5 parts by mass or more, or 10 parts by mass or more, or 20 parts by mass or more, and preferably 100 parts by mass or less, or 70 parts by mass or less, or 50 parts by mass or less, per 100 parts by mass of cellulose nanofibers.

[0192] The amount of amphiphilic molecules per 100 parts by mass of polyolefin resin (in one embodiment, unmodified polyolefin resin) may be 0.001 parts by mass or more, or 0.1 parts by mass or more, in one embodiment, 100 parts by mass or less, or 50 parts by mass or less, or 30 parts by mass or less.

[0193] In one embodiment, the content of amphiphilic molecules in the resin composition is preferably 0.3% by mass or more, or 0.5% by mass or more, or 1.0% by mass or more, and preferably 10.0% by mass or less, or 5.0% by mass or less, or 3.0% by mass or less.

[0194] (Method of adding dispersant) The method of adding the dispersant is not limited; for example, the following methods can be exemplified. (1) When producing a slurry in which cellulose nanofibers are dispersed in a liquid medium and drying it to obtain a dried product, A method for obtaining a dried cellulose nanofiber by mixing a dispersant with dried cellulose nanofibers, and A method for obtaining a dried cellulose nanofiber by adding a dispersant to a slurry and then drying it. (2) In the production of resin compositions, A method of pre-mixing and melt-kneading a thermoplastic resin, a dried cellulose nanofiber or a redispersion liquid obtained by dispersing the same in a liquid medium, and a dispersant, and then molding the mixture, and A method of molding a thermoplastic resin by adding a dispersant in advance, pre-mixing if necessary, then adding a dried cellulose nanofiber or a redispersion liquid obtained by dispersing it in a liquid medium, melt-mixing, and molding.

[0195] In a resin composition, the amount of dispersant can be easily determined by a person skilled in the art using a general method. The method of determination is not limited, but the following method can be exemplified. Using the resin composition, the resin composition is dissolved in a solvent that dissolves thermoplastic resins, and the soluble component 1 (thermoplastic resin and dispersant) and the insoluble component 1 (cellulose nanofibers and dispersant) are separated. The soluble component 1 is reprecipitated in a solvent that does not dissolve the thermoplastic resin but dissolves the dispersant, separating it into the insoluble component 2 (thermoplastic resin) and the soluble component 2 (dispersant). The insoluble component 1 is then dissolved in a dispersant-soluble solvent, separating it into the soluble component 3 (dispersant) and the insoluble component 3 (cellulose nanofibers). The amount of dispersant can be quantified by concentrating the soluble component 2 and the soluble component 3 (drying, air drying, vacuum drying, etc.). The concentrated dispersant can be identified and its molecular weight measured by the method described above.

[0196] ≪Method for manufacturing resin compositions≫ In one embodiment, the resin composition of this embodiment may be produced by a method comprising a first kneading step of kneading a kneading component containing a polyamide resin and cellulose nanofibers to obtain a masterbatch, and a second kneading step of kneading the masterbatch and a kneading component containing a polyolefin resin to obtain a resin composition.

[0197] In one embodiment, the first and second kneading steps are performed continuously within the same apparatus. As a result, the masterbatch containing cellulose nanofibers and polyamide resin, after being produced in the first kneading step, is supplied to the second kneading step while maintaining its fluid state and mixed with the polyolefin resin. When polyolefin resins and polyamide resins are mixed, generally, one forms a continuous phase and the other a nearly spherical dispersed phase. However, in the method of this embodiment, when the polyamide resin mixed with cellulose nanofibers is mixed with the polyolefin resin, unexpectedly, the polyamide resin can be dispersed in a non-spherical manner within the continuous phase of the polyolefin resin. This dispersed phase morphology is thought to be brought about by the cellulose nanofibers exhibiting a unique distribution state, such as being interposed between the polyolefin resin phase and / or the polyamide resin phase, rather than simply being dispersed within these phases.

[0198] In one embodiment, the first kneading step is carried out in the absence of the modified polyolefin resin. In a masterbatch formed in the presence of the modified polyolefin resin, the compatibilizing effect of the modified polyolefin resin makes it easier for cellulose nanofibers to be mixed with the polyolefin resin. When such a masterbatch is subjected to the second kneading step, the cellulose nanofibers readily migrate into the polyolefin resin phase. In this case, the contribution of cellulose nanofibers to the dispersion behavior of the polyamide resin decreases, making it easier for the polyamide resin to form a spherical dispersion phase rather than a non-spherical dispersion phase. Therefore, in one embodiment, the first kneading step is carried out in the absence of the modified polyolefin resin in order to stably achieve the desired distribution state of cellulose nanofibers and the desired dispersion phase morphology of the polyamide resin. In another embodiment, the first kneading step and / or the second kneading step are carried out in the presence of a dispersant, and the resin composition contains a dispersant. The following describes specific examples of the steps involved in each process.

[0199] <First mixing process> In this process, a masterbatch is obtained by kneading a compound containing a polyamide resin and cellulose nanofibers. The cellulose nanofibers may be kneaded alone or in combination with other components (e.g., a dispersant) as a preliminary masterbatch. The preliminary masterbatch may be produced by simultaneously adding and mixing cellulose nanofibers, a dispersant, and optionally additional components, or by pre-mixing components other than the dispersant to obtain a preliminary mixture, and then mixing the preliminary mixture with the dispersant. The obtained preliminary masterbatch may be mixed with a polyamide resin monomer to carry out a resin polymerization reaction, or the preliminary masterbatch may be mixed with a polyamide resin to form a masterbatch containing cellulose nanofibers and a polyamide resin.

[0200] Mixing methods for obtaining a preliminary masterbatch include, for example, agitators such as a rotating / revolving mixer, a planetary mixer, a homogenizer, a propeller-type agitator, a rotary agitator, an electromagnetic agitator, an open roll mixer, a Banbury mixer, a single-screw extruder, and a twin-screw extruder. Mixing may also be performed under heating to efficiently carry out shearing. Mixing by a homogenizer is preferred because it can promote dispersion by applying high shearing force and pressure.

[0201] On the other hand, if a preliminary masterbatch is not formed, cellulose nanofibers, polyamide resin or its monomer, and optionally additional components may be added to the kneader simultaneously or sequentially and kneaded. If polyamide resin monomer is supplied, the polymerization reaction is carried out in the kneader.

[0202] A single-screw or twin-screw extruder is preferred as the mixing method for obtaining the masterbatch. Extruders will be described later. <Second mixing process> In this process, a resin composition is obtained by kneading the masterbatch obtained in the first kneading step with a kneading component containing a polyolefin resin. For example, the masterbatch, which has been transported to a desired ratio with the polyolefin resin, may be added to the polyolefin resin and mixed, and then melt-kneaded. In one embodiment, the second kneading step is performed in the same apparatus and continuously as the first kneading step. This makes it possible to stably achieve the desired distribution state of cellulose nanofibers and the desired dispersed phase form of the polyamide resin. The mixing means for the second kneading step is preferably a single-screw extruder or a twin-screw extruder, but a twin-screw extruder is preferred for controlling the dispersibility of cellulose nanofibers. The resin composition produced in the second kneading step may be extruded into strands, cooled and solidified in a water bath to form pellets, or extruded into rods or cylinders and cooled to form extruded products, or extruded from a T-die to form sheets or films.

[0203] The ratio L / D, obtained by dividing the cylinder length (L) of the extruder by the screw diameter (D) throughout the first and second kneading processes, is preferably 30 or more, and particularly preferably 40 or more. Furthermore, 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.

[0204] Each screw inside the extruder cylinder is optimized by combining elements such as an elliptical, two-bladed screw-shaped conveying screw and a kneading disc, which is a mixing element.

[0205] The minimum processing temperatures recommended by thermoplastic resin suppliers are 180°C to 240°C for polyamide 6I, 255°C to 270°C for polyamide 66, 225°C to 240°C for polyamide 6, and 160°C to 180°C for polypropylene. The heating setting temperature for the first kneading step is preferably in a range 20°C higher than the recommended minimum processing temperature for polyamide resins, and is also preferably in a range 20°C higher than the recommended minimum processing temperature for polyolefin resins. By setting the mixing temperature within this range, the desired distribution state of cellulose nanofibers and the desired dispersed phase form of the polyamide resin can be stably achieved.

[0206] In one embodiment, the second kneading step is carried out in the presence of a modified polyolefin resin. In this case, the resin composition contains the modified polyolefin resin. The modified polyolefin resin contributes to improving the interfacial strength between the thermoplastic resin and cellulose nanofibers in the resin composition, but if it is present during the first kneading step, as described above, it adversely affects the distribution state of the cellulose nanofibers and the dispersed phase morphology of the polyamide resin. Therefore, it is advantageous to supply the modified polyolefin resin in the second kneading step.

[0207] <Shape of resin composition> The resin composition of this embodiment can be provided in various shapes. Specifically, it can be in the form of resin pellets, sheets, fibers, plates, rods, etc., but the resin pellet shape is preferred due to its ease of post-processing and ease of transport. Preferred resin pellet shapes include round, elliptical, and cylindrical shapes, and the shape may vary depending on the cutting method used during extrusion. For example, pellets cut using a method called underwater cutting are often round, pellets cut using a method called hot cutting are often round or elliptical, and pellets cut using a method called strand cutting are often cylindrical. The preferred pellet diameter for round pellets is 1 mm to 3 mm. The preferred diameter for cylindrical pellets is 1 mm to 3 mm, and the preferred length is 2 mm to 10 mm. From the viewpoint of operational stability during extrusion, it is desirable that the diameter and length be above the lower limit, and from the viewpoint of ease of engagement with the molding machine during post-processing, it is desirable that they be below the upper limit.

[0208] A desired molded article may be manufactured by molding a resin composition alone or together with other components into a desired shape. The combination of components and the molding method are not particularly limited and may be selected according to the desired molded article. The molding method is not limited to these, but injection molding, extrusion molding, blow molding, inflation molding, and foam molding can be used. Among these, injection molding is particularly preferred from the viewpoint of design and cost.

[0209] Uses of resin compositions 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, railway, vehicle, ship, and aerospace-related parts, electronic and electrical components, building and civil engineering materials, household goods, sports and leisure goods, wind turbine housing components, containers and packaging components, etc.

[0210] ≪Properties of the resin composition≫ <Tensile yield strength> In one aspect, the tensile yield strength of the resin composition 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.

[0211] <Tensile elongation at break> In one aspect, the tensile elongation at break of the resin composition 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.

[0212] <Flexural modulus> In one aspect, 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.

Examples

[0213] Hereinafter, exemplary embodiments of the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

[0214] ≪Evaluation method≫ <Cellulose nanofiber> [Preparation of porous sheet] First, the concentrated cake was added to tert-butanol, and further dispersed with a mixer or the like until there were no aggregates. It was adjusted so that the concentration became 0.5 mass% with respect to 0.5 g of the solid content weight of the cellulose nanofiber. 100 g of the obtained tert-butanol dispersion was filtered on filter paper. The filtrate was sandwiched between two larger filter papers without peeling it from the filter paper, and while pressing the edges of the larger filter paper with weights, it was dried in an oven at 150 °C for 5 minutes. Thereafter, the filter paper was peeled off to obtain a porous sheet with little strain. The air permeability resistance of this sheet is the basis weight of the sheet 10 g / m 2Porous sheets with a flow rate of 100 sec / 100 ml or less were used as measurement samples. The basis weight (W) of the sample after standing for 1 day in an environment of 23℃ and 50%RH (g / m²) 2 After measuring the air permeability resistance (R) (sec / 100ml), the air permeability resistance was measured using a Wangyan-type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01). At this time, 10 g / m was measured according to the following formula. 2 The value per unit area was calculated. Weight: 10g / m 2 Air permeability resistance (sec / 100ml) = R / W × 10

[0215] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), and Mw / Mn ratio] 0.88 g of porous sheet was weighed, cut into small pieces with scissors, lightly stirred, and then 20 mL of pure water was added and left for 1 day. Next, the water and solids were separated by centrifugation. Then 20 mL of acetone was added, lightly stirred, and left for 1 day. Next, the acetone and solids were separated by centrifugation. Then 20 mL of N,N-dimethylacetamide was added, lightly stirred, and left for 1 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 1 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, stirred with a stirrer, and visually confirmed to be dissolved. The solution containing dissolved cellulose nanofibers was filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The equipment and measurement conditions used are as follows. Equipment: Tosoh Corporation HLC-8120 Column: TSKgel SuperAWM-H (6.0mm I.D. × 15cm) × 2 tubes Detector: RI detector Eluent: N,N-dimethylacetamide (lithium chloride 0.2%) Flow rate: 0.6mL / min Calibration curve: Pullulan equivalent For 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.

[0216] [Average content of alkali-soluble polysaccharides] The alkali-soluble polysaccharide content was determined for cellulose nanofibers by subtracting the α-cellulose content from the holocellulose content (Wise method), using the method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000). The alkali-soluble polysaccharide content was calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide content was taken as the average alkali-soluble polysaccharide content of the cellulose nanofibers. For acetylated cellulose nanofibers, the average alkali-soluble polysaccharide content of the raw material before acetylation was used.

[0217] [Degree of crystallinity] X-ray diffraction measurements were performed on the porous sheet, and the degree of crystallinity was calculated using the following formula. Crystallinity (%)=[I (200) -I (amorphous) ] / I (200) ×100 I (200) :Diffraction peak intensity at the 200 plane (2θ=22.5°) in cellulose type I crystals I (amorphous) : The halo peak intensity due to amorphous material in type I cellulose crystals, specifically 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) MiniFlex device (manufactured by Rigaku Corporation) Operation axis 2θ / θ Source CuKα Measurement method: Continuous Voltage 40kV Current 15mA Starting angle 2θ=5° Ending angle 2θ = 30° Sampling width 0.020° Scan speed 2.0° / min Sample: A porous sheet was pasted onto a sample holder

[0218] [Number average fiber length and number average fiber diameter] The concentrated cake was diluted with tert-butanol to 0.01% by mass, and dispersed using a high-shear homogenizer (manufactured by IKA, trade name "Ultra Turrax T18") under the treatment conditions: rotation speed 15,000 rpm × 3 minutes. The cast and air-dried product on an osmium-evaporated silicon substrate was measured using a high-resolution scanning electron microscope (Regulus 8220, manufactured by Hitachi High-Technologies Corporation). The measurement was carried out by adjusting the magnification so that at least 100 cellulose fibers were observed. The lengths (L) and diameters (D) of 100 randomly selected cellulose fibers were measured, and the additive average of each 100 cellulose fibers was calculated as the number average fiber length and the number average fiber diameter.

[0219] [Specific surface area] Using a specific surface area and pore size distribution measuring device (Nova-4200e, manufactured by Quantachrome Instruments), after drying approximately 0.2 g of the porous sheet under vacuum at 120 °C for 5 hours, the nitrogen gas adsorption amount at the boiling point of liquid nitrogen was measured at 5 points in the range where the relative vapor pressure (P / P0) was 0.05 or more and 0.2 or less (multi-point method). Then, the BET specific surface area (m 2 / g) was calculated using the device program.

[0220] [Degree of acyl substitution DS] The infrared spectra of five locations of the porous sheet by the ATR-IR method were measured using a Fourier transform infrared spectrometer (FT / IR-6200, manufactured by JASCO Corporation). The infrared spectrum measurement was carried out under the following conditions. Number of accumulations: 64 times, Wavenumber resolution: 4 cm -1 , Measurement wavenumber range: 4000~600 cm -1 , ATR crystal: Diamond, Incident angle: 45°

[0221] From the obtained IR spectrum, the IR index was calculated using the following formula: IR Index = H1730 / H1030 The calculation was performed according to the formula. In the formula, H1730 and H1030 are 1730 cm. -1 , 1030cm -1 This is the absorbance in the absorption band of the CO stretching vibration of the cellulose skeleton chain. However, each value is 1900 cm². -1 and 1500cm -1 The line connecting them is 800cm -1 and 1500cm -1 The line connecting these points is used as the baseline, and this value represents the absorbance when this baseline is set to 0. Then, the average degree of replacement at each measurement location was calculated from the IR index according to the following formula, and the average value was defined as DS. DS = 4.13 × IR Index

[0222] [DS heterogeneity ratio (CV)] The porous sheets subjected to the above ATR-IR measurement were freeze-dried to prepare cellulose powder samples. The powder was placed on 10 2.5 mmφ dish-shaped sample holders, flattened by pressing down the surface, and each was subjected to XPS measurement. Peak separation was performed on the obtained C1s spectra, and the DSs of each sample was calculated using the following formula based on the area intensity (Ixf) of the peak derived from the OC=O bond of the acetyl group (286 eV) versus the area intensity (Ixp) of the peak attributed to carbon C2-C6 of the pyranose ring of cellulose (289 eV, CC bond), and the average of these was taken as the DSs of the cellulose nanofiber. DSs = (Ixf) × 5 / (Ixp)

[0223] The XPS measurement conditions used were as follows: Equipment used: ULVAC-FI VersaProbeII Excitation source: mono.AlKα 15kV × 3.33mA Analysis size: Approximately 200 μmφ Photoelectron extraction angle: 45° Capture area Narrow scan: C 1s, O 1s Pass Energy: 23.5 eV

[0224] Based on the above DS and DSs, the DS non-uniformity ratio (CV) was calculated according to the following formula. DS heterogeneity ratio (CV) = DSs / DS

[0225] [Thermal decomposition onset temperature (T D )] Thermal analysis of the porous sheet was performed using the following measurement method. Device: Rigaku Thermo plus EVO2 Sample: Circular pieces cut from a porous sheet were stacked in aluminum sample pans, with 10 mg of each piece placed on top. Sample amount: 10 mg Measurement conditions: The temperature was increased 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, and then continued to increase to 450°C at a rate of 10°C / min. T D Calculation Method: The temperature was determined from a graph with temperature on the horizontal axis and weight retention percentage on the vertical axis. Starting from the weight of the porous sheet at 150°C (when moisture is almost completely removed) (weight loss of 0 wt%), the temperature was further increased, and a straight line was obtained that passes through the temperature at which the weight decreased by 1 wt% and the temperature at which the weight decreased by 2 wt%. The temperature at the point where this straight line intersects with the horizontal line (baseline) passing through the starting point of 0 wt% weight loss was defined as the thermal decomposition onset temperature (T D )

[0226] [1wt% weight loss temperature] Said T D The temperature at which a 1 wt% weight loss occurred during the calculation was defined as the 1 wt% weight loss temperature.

[0227] [Weight change rate at 250℃] Device: Rigaku Thermo plus EVO2 Sample: Circular pieces cut from a porous sheet were stacked in aluminum sample pans, with 10 mg of each piece placed on top. Sample amount: 10 mg Measurement conditions: The temperature was raised 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 raised 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 of reaching 250°C was used as the starting point, and the weight after holding at 250°C for 2 hours was defined as W1, which was calculated using the following formula. Weight change rate at 250℃ (%): (W1-W0) / W0×100

[0228] <Thermoplastic resin> [Melting point and glass transition temperature] The measurements were taken using the method described in JIS K7121.

[0229] [Mw] The measured values ​​were obtained using the method described in JIS K7252.

[0230] [Melt flow rate (MFR) at 230°C] The measurement was performed using the method described in JIS K7210.

[0231] [Concentration of terminal amino groups and terminal carboxyl groups] By the method described in Japanese Patent Publication No. 7-228775, 1 The measurement was performed using 1H NMR (nuclear magnetic resonance) with deuterated trifluoroacetic acid as the measurement solvent, and with a total of 300 or more scans.

[0232] [Acid value] The measurement was performed according to the method described in JIS K0070.

[0233] <Resin composition> [Tensile yield strength and tensile elongation at break] Tensile yield strength and tensile elongation at fracture were measured in accordance with ISO 527-1. For molded pieces that fractured before reaching yield, the maximum strength was used as a substitute.

[0234] [Flexural modulus] The obtained pellets were molded using an injection molding machine under conditions compliant with JIS K6920-2 to produce multipurpose test specimens compliant with ISO 294-3. The injection molding temperatures were 260°C for PA6, 280°C for PA66, 200°C for PP, and 210°C for POM. The flexural modulus was measured in accordance with ISO 179. Since polyamides undergo changes due to moisture absorption, the specimens were stored in aluminum moisture-proof bags immediately after molding to suppress moisture absorption.

[0235] [Constituent resins of the continuous phase and dispersed phase] The following conditions were used for evaluation using a scanning transmission electron microscope (STEM). The resin composition pellets were trimmed to an appropriate size, and ultrathin sections with MD-ND cross-sections were prepared using a cryomicrotome at a set thickness of 100 nm. These sections were loaded onto a copper mesh and stained with ruthenium to obtain samples for microscopy. The STEM observation conditions were as follows. Equipment: S-5500 (manufactured by Hitachi, Ltd.) Acceleration voltage: 30.0kV Detector: BF-STEM (transmission image) In the obtained transmission images, the dispersed phase was a polyamide resin and the continuous phase was a polyolefin resin (however, in Comparative Example 3, the dispersed phase was a polyolefin resin and the continuous phase was a polyamide resin), and the material with a fibrous structure was identified as CNF and the following observations were made. Twenty images were taken at a magnification of 50,000x in an arbitrary field of view.

[0236] [Confirmation of CNF distribution, and the proportion of CNF with one end in the continuous phase and the other end in the dispersed phase] This was confirmed using scanning transmission electron microscopy (STEM) images. If the number of CNFs was less than 50, additional images were taken to ensure the total number was 50 or more.

[0237] [Ratio of Ferret's long diameter to Ferret's short diameter] The major and minor axes of the dispersed phase were measured in scanning transmission electron microscope (STEM) images, and the average values ​​were calculated.

[0238] [Roughness of the dispersed phase] The area (S) of the dispersed phase (as cross-sectional area) is obtained in the scanning transmission electron microscope (STEM) image, and the cross-sectional area / (perimeter length 2 The average value of ) × 4π was calculated.

[0239] [Equivalent spherical diameter of the dispersed phase] The area (S) of the dispersed phase was obtained from scanning transmission electron microscope (STEM) images, and the average value of √4S / π was calculated.

[0240] [Presence or absence of coarse aggregates] Using an optical microscope, arbitrary sections of the resin molded piece were observed, and components with both long and short axes larger than 100 μm were identified as coarse aggregates. If five or more coarse aggregates were observed in a 10 mm square field of view, it was classified as having coarse aggregates; if four or fewer were observed, it was classified as not having coarse aggregates.

[0241] ≪Materials used≫ <(A) Cellulose nanofiber> CNF-A: Acetylcellulose nanofiber Five parts by mass of CNF-D concentrated cake (solid content 20% by mass) and 95 parts by mass of DMSO were added to a NETZSCH Vakumix KAPPA VITA® homomixer (tank size 35L) and dispersed at 2500 rpm (peripheral speed 12 m / s) using the homomixer to obtain 100 parts by mass of DMSO slurry (solid content 1.0% by mass). Next, two 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 was added while stirring. The solids were then filtered off. The obtained solids were dispersed with 100 parts by mass of water using the homomixer, and this washing operation was repeated six times to obtain five parts by mass of CNF-A concentrated cake (solid content 20% by mass).

[0242] CNF-B: Discrete Refiner - Unmodified Cellulose Nanofibers Three parts by mass of cotton linter pulp were immersed in 27 parts by mass of water and dispersed using a pulper. Thirty parts by mass of the pulper-treated cotton linter pulp slurry (of which three parts by mass were cotton linter pulp) were dispersed in water with 170 parts by mass of water (solid content 1.5% by mass). Using an SDR14 type laboratory refiner (pressure-type disk type) manufactured by Aikawa Iron Works Co., Ltd. as a disc refiner, the aqueous dispersion was beaten for 30 minutes with a clearance of 1 mm between the disks to obtain a slurry (solid content concentration: 1.5% by mass). The slurry was then concentrated to a solid content of 20% by mass using a dewatering machine to obtain 15 parts by mass of CNF-B concentrated cake.

[0243] CNF-C: Commercially available cellulose nanofiber Commercially available Celish KY100G (manufactured by Daicel Finechem) was used as the CNF-C cake.

[0244] CNF-D: Unmodified cellulose nanofibers defibrated using a discreeter and high-pressure homogenizer. Three parts by mass of cotton linter pulp were immersed in 27 parts by mass of water and dispersed using a pulper. Thirty parts by mass of the pulper-treated cotton linter pulp slurry (of which three parts by mass were cotton linter pulp) were dispersed in water with 170 parts by mass of water (solid content 1.5% by mass). An SDR14 type laboratory refiner (pressure-type disk type) manufactured by Aikawa Iron Works Co., Ltd. was used as a disc refiner, and the aqueous dispersion was beaten for 30 minutes with a clearance of 1 mm between the disks. Subsequently, thorough beating was performed under conditions where 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 then subjected to 10 micronization treatments using a high-pressure homogenizer (NSO15H manufactured by Nilo Soavi (Italy)) at an operating pressure of 100 MPa to obtain a slurry (solid content concentration: 1.5% by mass). Then, the mixture was concentrated to a solid content of 20% by mass using a dehydrator, yielding 15 parts by mass of CNF-D concentrated cake.

[0245] The properties of cellulose nanofibers are shown in Table 1.

[0246] [Table 1]

[0247] <(B) Thermoplastic resin> The materials used are shown in Table 2. Polyamide 6I (PA6I) was synthesized by the following procedure using the "thermal fusion polymerization method". First, 1500 g of an equimolar salt of isophthalic acid and hexamethylenediamine, along with 1.5 mol% excess adipic acid and 0.5 mol% acetic acid relative to the total equimolar salt components, were dissolved in 1500 g of distilled water to prepare a homogeneous aqueous solution of 50% by mass of the raw material monomers. Next, the solution was concentrated by gradually removing water vapor while stirring at a temperature of approximately 110°C to 150°C until the solution concentration reached 70% by mass. Then, the internal temperature was raised to 220°C. At this time, the autoclave was pressurized to 1.8 MPa. The reaction was carried out for 1 hour, while gradually removing water vapor and maintaining the pressure at 1.8 MPa until the internal temperature reached 245°C. Next, the pressure was reduced over 30 minutes. Then, the autoclave was maintained under reduced pressure of 650 torr (86.66 kPa) for 10 minutes using a vacuum device. At this time, the final internal temperature of polymerization was 265°C. Next, the material was pressurized with nitrogen and formed into strands from the lower spindle (nozzle), then water-cooled and cut to discharge it in pellet form. The pellets were then dried at 100°C under a nitrogen atmosphere for 12 hours to obtain polyamide 6I.

[0248] [Table 2]

[0249] <(C) Dispersant> PEG-PPG (manufactured by Sanyo Chemical Industries, Ltd., GL-3000) Hydrogenated castor oil (manufactured by Aoki Oil & Fat Industry Co., Ltd., RCW-20) Liquid rubber (Clay Valley Corporation, Ricon 181)

[0250] [Extruder Configuration] Mixing was performed using a twin-screw extruder (STEER OMEGA30H, L / D=72) with 15 cylinder blocks. A side feeder was installed in cylinder 11 to allow for the addition of resin pellets. A vent port was installed at the top of cylinder 14 to allow for reduced pressure suction, and vacuum suction was performed. A 50-mesh screen mesh was installed between the die adapter and the die head.

[0251] The screw configuration consists of a conveying zone comprising only conveying screws in cylinders 1-3, two clockwise kneading discs (feed-type kneading discs; hereinafter sometimes simply referred to as RKDs) in cylinders 4-11 arranged in order from the upstream side: two clockwise kneading discs (non-conveying type kneading discs; hereinafter sometimes simply referred to as NKDs), a conveying zone, one RKD followed by two NKDs, a conveying zone, two NKDs, and a conveying zone, two cylinders 12 with two NKDs followed by one counterclockwise screw, and cylinder 13 as a conveying zone.

[0252] Preparation of resin compositions [Examples 1-15, Comparative Examples 2-3] The above materials were used in the formulations shown in Tables 3 and 4, and the resin composition was prepared according to the following procedure.

[0253] Cellulose cake and dispersant were dried under reduced pressure using a planetary mixer according to the formulations shown in Tables 3 and 4 to obtain a dried cellulose product. The above-mentioned dried cellulose and resin were mixed in the proportions shown in Tables 3 and 4, and kneaded in a twin-screw extruder to obtain cellulose-containing resin pellets as a resin composition. The dried cellulose and polyamide were supplied to the upstream feed port of the twin-screw extruder, while the unmodified and modified polyolefins were supplied via side feeders.

[0254] [Comparative Example 1] A resin composition was obtained in the same manner as in Example 1, except that the modified polyolefin was supplied from the upstream supply port.

[0255] [Comparative Examples 4 and 5] A resin composition was obtained in the same manner as in Example 1, except that the unmodified polyolefin and the modified polyolefin were supplied from the upstream supply port.

[0256] [Reference examples 1~4] The resin was fed into a twin-screw extruder on its own and kneaded under the same conditions as in Example 1 to obtain a resin composition. The evaluation results are shown in Tables 3 and 4.

[0257] [Table 3]

[0258] [Table 4] [Industrial applicability]

[0259] The resin composition according to the present invention can be suitably applied to various resin molded article applications.

Claims

1. A method for producing a resin composition comprising a polyolefin resin, a polyamide resin, and cellulose nanofibers, A first kneading step involves kneading a compound containing a polyamide resin and cellulose nanofibers to obtain a masterbatch, and A second kneading step involves kneading a kneading component containing the masterbatch and a polyolefin resin to obtain a resin composition. Includes, The first kneading step and the second kneading step are performed continuously within the same apparatus. The first kneading step is carried out in the absence of the modified polyolefin resin. The resin composition comprises a continuous phase of a polyolefin resin and a dispersed phase of a polyamide resin. The aforementioned dispersed phase is a non-spherical dispersed phase, A method comprising the resin composition wherein at least a portion of the cellulose nanofibers are interposed between the continuous phase and the dispersed phase.

2. The method according to claim 1, wherein the resin composition has a Ferret major axis / Ferret minor axis ratio of the dispersed phase of 1.5 or more.

3. The method according to claim 1 or 2, wherein the degree of unevenness of the dispersed phase in the resin composition is 0.01 to 0.

9.

4. The method according to claim 1 or 2, wherein at least a portion of the cellulose nanofibers interposed between the continuous phase and the dispersed phase are in contact only with the continuous phase at one end in the fiber length direction and in contact only with the dispersed phase at the other end in the fiber length direction.

5. The method according to claim 1 or 2, wherein the ratio Lp / Lc of the spherical equivalent diameter Lp of the dispersed phase to the fiber length Lc of the cellulose nanofibers in the resin composition is 0.001 to 0.

1.

6. The method according to claim 1 or 2, wherein the weight-average molecular weight of the polyamide resin is 1,000 to 100,000.

7. Concentration of terminal amino groups in the polyamide resin [NH 2 The method according to claim 1 or 2, wherein [ ] is 1 μmol / g to 150 μmol / g.

8. The method according to claim 1 or 2, wherein the concentration of terminal carboxyl groups [COOH] of the polyamide resin is 20 μmol / g to 500 μmol / g.

9. The method according to claim 1 or 2, wherein the polyamide resin has an aromatic skeleton and an aliphatic skeleton.

10. The method according to claim 1 or 2, wherein the polyamide resin is polyamide 6I.

11. The method according to claim 1 or 2, wherein the difference Tg1-Tg2 between the glass transition temperature Tg1 of the polyamide resin and the glass transition temperature Tg2 of the polyolefin resin is greater than 80°C.

12. The method according to claim 1 or 2, wherein the polyolefin resin is a polypropylene resin.

13. The method according to claim 12, wherein the weight-average molecular weight of the polypropylene resin is 10,000 to 300,000.

14. The method according to claim 12, wherein the melt flow rate (MFR) of the polypropylene resin at 230°C is 3 g / 10 min to 30 g / 10 min.

15. The method according to claim 1 or 2, wherein the number-average fiber diameter of the cellulose nanofibers is 2 nm to 1000 nm.

16. The method according to claim 1 or 2, wherein the cellulose nanofiber is a chemically modified cellulose nanofiber.

17. The method according to claim 16, wherein the chemically modified cellulose nanofiber is acetylated cellulose nanofiber.

18. The method according to claim 16, wherein the degree of acyl substitution (DS) of the chemically modified cellulose nanofiber is 0.1 to 2.

0.

19. The method according to claim 1 or 2, wherein the resin composition comprises 100 parts by mass of an unmodified polyolefin resin, 0.1 to 50 parts by mass of a polyamide resin, and 0.1 to 50 parts by mass of cellulose nanofibers.

20. The method according to claim 1 or 2, wherein the second kneading step is carried out in the presence of a modified polyolefin resin, and the resin composition contains the modified polyolefin resin. Including doing,

21. The method according to claim 20, wherein the modified polyolefin resin is an acid-modified polyolefin resin.

22. The method according to claim 21, wherein the acid-modified polyolefin resin is an acid-modified polypropylene resin.

23. The method according to claim 21, wherein the acid value of the acid-modified polyolefin resin is 1 mg KOH / g to 200 mg KOH / g.

24. Concentration of terminal amino groups in the polyamide resin [NH 2 The ratio of the carboxyl group concentration [COOH]MAH of the acid-modified polyolefin resin to [NH] 2 The method according to claim 21, wherein ] is greater than 0.

1.

25. The method according to claim 1 or 2, wherein the first kneading step and / or the second kneading step are carried out in the presence of a dispersant, and the resin composition contains the dispersant.

26. A resin composition comprising a polyolefin resin, a polyamide resin, and cellulose nanofibers, The resin composition comprises a continuous phase of the polyolefin resin and a dispersed phase of the polyamide resin. The aforementioned dispersed phase is a non-spherical dispersed phase, A resin composition in which at least a portion of the cellulose nanofibers is interposed between the continuous phase and the dispersed phase.

27. The resin composition according to claim 26, wherein the ratio of the Ferret major axis to the Ferret minor axis of the dispersed phase is 1.5 or more.

28. The resin composition according to claim 26 or 27, wherein the degree of unevenness of the dispersed phase is 0.01 to 0.

9.

29. The resin composition according to claim 26 or 27, wherein at least a portion of the cellulose nanofibers interposed between the continuous phase and the dispersed phase are in contact only with the continuous phase at one end in the fiber length direction and in contact only with the dispersed phase at the other end in the fiber length direction.

30. The resin composition according to claim 26 or 27, wherein the ratio Lp / Lc of the spherical equivalent diameter Lp of the dispersed phase to the fiber length Lc of the cellulose nanofibers is 0.001 to 0.

1.

31. The resin composition according to claim 26 or 27, wherein the weight-average molecular weight of the polyamide resin is 1,000 to 100,000.

32. Concentration of terminal amino groups in the polyamide resin [NH 2 The resin composition according to claim 26 or 27, wherein the concentration is 1 μmol / g to 150 μmol / g.

33. The resin composition according to claim 26 or 27, wherein the concentration of terminal carboxyl groups [COOH] of the polyamide resin is 20 μmol / g to 500 μmol / g.

34. The resin composition according to claim 26 or 27, wherein the polyamide resin has an aromatic skeleton and an aliphatic skeleton.

35. The resin composition according to claim 26 or 27, wherein the polyamide resin is polyamide 6I.

36. The resin composition according to claim 26 or 27, wherein the difference Tg1-Tg2 between the glass transition temperature Tg1 of the polyamide resin and the glass transition temperature Tg2 of the polyolefin resin is greater than 80°C.

37. The resin composition according to claim 26 or 27, wherein the polyolefin resin is a polypropylene resin.

38. The resin composition according to claim 37, wherein the weight-average molecular weight of the polypropylene resin is 10,000 to 300,000.

39. The resin composition according to claim 37, wherein the melt flow rate (MFR) of the polypropylene resin at 230°C is 3 g / 10 min to 30 g / 10 min.

40. The resin composition according to claim 26 or 27, wherein the number-average fiber diameter of the cellulose nanofibers is 2 nm to 1000 nm.

41. The resin composition according to claim 26 or 27, wherein the cellulose nanofibers are chemically modified cellulose nanofibers.

42. The resin composition according to claim 41, wherein the chemically modified cellulose nanofiber is acetylated cellulose nanofiber.

43. The resin composition according to claim 41, wherein the degree of acyl substitution (DS) of the chemically modified cellulose nanofiber is 0.1 to 2.

0.

44. The resin composition according to claim 26 or 27, comprising 100 parts by mass of an unmodified polyolefin resin, 0.1 to 50 parts by mass of a polyamide resin, and 0.1 to 50 parts by mass of cellulose nanofibers.

45. The resin composition according to claim 26 or 27, further comprising a modified polyolefin resin.

46. The resin composition according to claim 45, wherein the modified polyolefin resin is an acid-modified polyolefin resin.

47. The resin composition according to claim 46, wherein the acid-modified polyolefin resin is an acid-modified polypropylene resin.

48. The resin composition according to claim 46, wherein the acid value of the acid-modified polyolefin resin is 1 mg KOH / g to 200 mg KOH / g.

49. Concentration of terminal amino groups in the polyamide resin [NH 2 The resin composition according to claim 46, wherein the ratio of the carboxyl group concentration [COOH]MAH of the acid-modified polyolefin resin to [ ] is greater than 0.

1.

50. The resin composition according to claim 26 or 27, further comprising a dispersant.

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