JP5940933B2 - Resin composition - Google Patents

Description

  The present invention relates to a resin composition containing fine cellulose fibers having a nano-sized fiber diameter and having high mechanical strength.

  Conventionally, for the purpose of improving the mechanical strength and the like of a resin, it is widely performed to add fine cellulose fibers having a nano-sized fiber diameter to the resin. However, since the fine cellulose fiber is a hydrophilic fiber, when it is blended in a hydrophobic resin, it aggregates in the resin and is not uniformly dispersed, so that there is a problem that the intended mechanical strength cannot be improved. In view of this, fine cellulose fibers are modified by surface modification or the like to make them hydrophobic so that they can be dispersed uniformly in a hydrophobic resin.

  For example, Patent Document 1 discloses an average fiber as a method for producing a cellulose fiber-containing resin material in which fine cellulose fibers are uniformly dispersed in a thermoplastic resin such as polyethylene terephthalate and polycarbonate, and the mechanical strength of the thermoplastic resin is improved. A method of further mixing a second thermoplastic resin having a molecular weight larger than that of the first thermoplastic resin after mixing the surface-treated cellulose fibers having a diameter of 2 to 200 nm, the organic solvent, and the first thermoplastic resin is described. ing. Further, in Patent Document 1, as an example of the surface-treated cellulose fiber, one obtained by chemically modifying a hydroxyl group of cellulose fiber with a modifier such as an acid, an alcohol, an acid anhydride, or 2,2,6,6- Examples include those obtained by oxidizing cellulose fibers with an oxidizing agent in the presence of an N-oxyl compound such as tetramethyl-1-piperidine-N-oxyl (hereinafter also referred to as TEMPO). In the oxidation treatment of cellulose fibers using the latter TEMPO catalyst, only the primary hydroxyl group at the C6 position in the glucopyranose ring, which is a constituent monomer unit of cellulose, is selectively oxidized and oxidized to the carboxy group via the aldehyde. .

  Patent Document 2 describes a fine cellulose ester fiber having a uronic acid residue esterified in a molecule and a cellulose I-type crystal structure as a fine cellulose fiber having improved adhesion to a resin. Has been. According to Patent Document 2, this fine cellulose ester fiber is obtained by adding an organic onium compound to a dispersion of hydrophilic fine cellulose fibers containing a carboxy group, which is obtained through oxidation treatment of cellulose fibers using a TEMPO catalyst. By adding a solution containing, ion exchange between the alkali metal carboxylate on the surface of the fine cellulose fiber and the organic onium ion of the organic onium compound is performed to make the fine cellulose fiber hydrophobic (lipophilic), The hydrophobized fine cellulose fiber is said to be obtained by reacting an alkylating agent with esterification.

  Patent Document 3 describes a resin composition having excellent mechanical strength, which includes a hydrophobic resin such as an epoxy resin or a phenol resin and a hydrophobized fine cellulose fiber. This hydrophobized fine cellulose fiber is obtained by adding and stirring an organic cationic substance to a dispersion of hydrophilic fine cellulose fibers containing a carboxy group, which is obtained through oxidation treatment of cellulose fibers using a TEMPO catalyst. The hydrogen ion of the carboxylic acid group on the surface of the fine cellulose fiber is ion-exchanged with a hydrophobic organic cation.

JP 2010-265357 A JP 2010-59571 A JP 2011-47084 A

  When a resin composition is produced by blending fine cellulose fibers modified from hydrophilic to hydrophobic in accordance with the description in Patent Document 1 or 3 for the purpose of improving the mechanical strength of the resin, the resin However, it is unintentionally colored in a color different from the original color of the resin, and there is a problem that the obtained resin composition exhibits an unintended color. Such a resin composition having a color different from the original color of the contained resin is inferior in versatility because its use is limited. Patent Documents 1 to 3 do not mention the problem of coloring the resin, and no means for solving the problem has been provided.

  Accordingly, an object of the present invention is to provide a resin composition containing fine cellulose fibers and a resin, having a practically sufficient mechanical strength and being less colored.

  The present inventors pay attention to the characteristics (high crystallinity, having a high aspect ratio, etc.) of hydrophilic fine cellulose fibers containing a carboxy group obtained through oxidation treatment of cellulose fibers using a TEMPO catalyst. As a result of various studies on methods that can effectively improve the mechanical strength of the resin by taking advantage of such properties, the surface of the fine cellulose fiber is selectively hydrophobized to thereby improve the crystallinity of the fine cellulose fiber. As a result of further finding that the reduction and the reduction in the mechanical strength improvement effect resulting from the reduction can be avoided, the fine cellulose can be obtained by selectively amidating the carboxy group of the cellulose constituting the fine cellulose fiber. It has been found that the fiber surface can be selectively hydrophobized while maintaining the crystal structure unique to the fiber to improve the compatibility with the resin. It is also found that the combined use of a fine cellulose fiber composite obtained by such an amidation reaction and a specific resin can effectively improve the mechanical strength while effectively suppressing the coloring of the resin. did.

  The present invention has been made on the basis of the above-mentioned knowledge. A fine cellulose fiber composite in which a hydrocarbon group is bonded to a fine cellulose fiber through an amide bond, a polyolefin resin, a polyvinyl chloride resin, and a polyamide resin. And the said subject is solved by providing the resin composition containing 1 or more types of resin selected from the group which consists of polycarbonate-type resin.

  Moreover, this invention is a manufacturing method of the said resin composition, Comprising: The said fine cellulose fiber composite body and the said resin are mixed, the uniform mixture is obtained, and resin which has the process of shape | molding this uniform mixture in arbitrary shapes The problem is solved by providing a method for producing the composition.

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition which contains fine cellulose fiber and resin, has sufficient mechanical strength practically, and there is little coloring of this resin is provided.

  The resin composition of the present invention contains a fine cellulose fiber composite and a specific resin as essential components. Each component will be described in detail below.

  The fine cellulose fiber composite used in the present invention is obtained by bonding a hydrocarbon group to a fine cellulose fiber as a raw material via an amide bond. This amide bond is preferably located at the C6 position of the glucopyranose ring which is a constituent monomer unit of cellulose constituting the fine cellulose fiber composite. The fine cellulose fiber composite used in the present invention is obtained by selectively amidating the carboxy group of a fine cellulose fiber containing a carboxy group, as will be described later. That the amide bond is located at the C6 position in the glucopyranose ring in C6 position in the glucopyranose ring of cellulose constituting the fine cellulose fiber is that the fine cellulose fiber that is the starting material for the amidation reaction Means having a carboxy group (carboxy group to be amidated). Hereinafter, unless otherwise specified, “fine cellulose fiber” means a fine cellulose fiber having no amide bond (carboxy group is not amidated) which is a starting material of the fine cellulose fiber composite, “Fine cellulose fiber composite” means fine cellulose fibers in which a carboxy group is amidated.

  The average fiber diameter of the fine cellulose fiber composite used in the present invention is preferably 1 nm or more, and preferably 200 nm or less, from the viewpoint of more surely improving the mechanical strength of the resin composition. The thickness is preferably 100 nm or less, particularly preferably 50 nm or less, more specifically preferably 1 to 200 nm, further preferably 1 to 100 nm, and particularly preferably 1 to 50 nm. The average fiber diameter is measured by the following measuring method. The average fiber diameter of each of the “fine cellulose fibers” as the raw material and the “fine cellulose fiber composite” obtained by amidating them can be measured according to the following measurement method.

<Measuring method of average fiber diameter of fine cellulose fiber or fine cellulose fiber composite>
An atomic force microscope was prepared by preparing a dispersion in which water or ethanol was added to cellulose fibers having a solid content concentration of 0.0001% by mass, and the dispersion was dropped onto mica (mica) and dried. (AFM, Nanoscope III Tapping mode AFM, manufactured by Digital instrument, probe uses Nano Sensors Point Probe (NCH)) is used to measure the fiber height of the cellulose fibers in the observation sample. And in the microscope image which can confirm a cellulose fiber, five or more fine cellulose fibers are extracted, and an average fiber diameter is computed from those fiber heights. In general, the minimum unit of cellulose nanofibers prepared from higher plants is packed in a square shape with 6 x 6 molecular chains. Therefore, the height that can be analyzed by AFM images is regarded as the fiber width. Can do.

  The carboxy group content of the fine cellulose fiber used in the present invention is preferably 0.1 mmol / g or more, more preferably 0.4 mmol / g or more, particularly preferably 0.6 mmol / g or more, and preferably 3 mmol. / G or less, more preferably 2 mmol / g or less, particularly preferably 1.8 mmol / g or less, more specifically preferably 0.1 to 3 mmol / g, more preferably 0.4 to 2 mmol / g, particularly Preferably it is 0.6-1.8 mmol / g. In the resin composition of the present invention, cellulose fibers having a carboxy group content outside such a range may be unintentionally contained as impurities.

  The fact that the fine cellulose fiber contains a carboxy group of 0.1 mmol / g or more and 3 mmol / g or less is preferable for stably obtaining fine cellulose fibers having a fine average fiber diameter of 200 nm or less. It is an important element. That is, in the process of biosynthesis of natural cellulose, normally, nanofibers called microfibrils are first formed, and these are multi-bundleed to construct a higher-order solid structure. Fine cellulose fibers used in the present invention As will be described later, the fine cellulose fiber that is a raw material of the composite is obtained in principle, and is a driving force of strong cohesion between microfibrils in a naturally derived cellulose solid raw material. In order to weaken the hydrogen bond between the surfaces, it is obtained by oxidizing a part thereof and converting it to a carboxy group. Therefore, the larger the total amount of carboxy groups present in cellulose (carboxy group content), the smaller the fiber diameter, the more stable it can exist, and in water, an electric repulsive force is generated. In addition, the tendency of microfibrils to break apart without maintaining agglomeration is increased, and the dispersion stability of nanofibers is further increased. When the carboxy group content is less than 0.1 mmol / g, it becomes difficult to obtain fine cellulose fibers (fine cellulose fiber composite) having a fine average fiber diameter, and the dispersion stability in a polar solvent such as water is low. May decrease. The carboxy group content of the fine cellulose fiber is measured by the following measuring method. “Cellulose fiber” in the following measurement method can be read as “fine cellulose fiber” as a raw material.

<Measuring method of carboxy group content of fine cellulose fiber>
Take a cellulose fiber with a dry mass of 0.5 g in a 100 ml beaker, add ion-exchanged water to make a total of 55 ml, add 5 ml of 0.01 M sodium chloride aqueous solution to prepare a dispersion, and until the cellulose fibers are sufficiently dispersed The dispersion is stirred. 0.1M hydrochloric acid is added to this dispersion to adjust the pH to 2.5-3, and 0.05M sodium hydroxide aqueous solution is waited for using an automatic titrator (AUT-50, manufactured by Toa DKK Co., Ltd.). The solution is dropped into the dispersion under the condition of 60 seconds, and the conductivity and pH values are measured every minute, and the measurement is continued until the pH is about 11, thereby obtaining an conductivity curve. From this conductivity curve, a sodium hydroxide titration amount is obtained, and the carboxy group content of the cellulose fiber is calculated by the following formula.
Carboxy group content of fine cellulose fiber (mmol / g) = sodium hydroxide titration × sodium hydroxide aqueous solution concentration (0.05 M) / mass of cellulose fiber (0.5 g)

  The fine cellulose fibers used in the present invention have an average aspect ratio (fiber length / fiber diameter) of preferably 10 or more, more preferably 50 or more, particularly preferably 100 or more, and preferably 1000 or less, more preferably 500 or less. Especially preferably, it is 350 or less, More specifically, Preferably it is 10-1000, More preferably, it is 50-500, Most preferably, it is 100-350. A fiber having an average aspect ratio in such a range has characteristics that it has excellent dispersibility when mixed with a resin, high mechanical strength, and is particularly difficult to brittle fracture. The average aspect ratio is measured by the following measurement method. The average aspect ratio of the cellulose fibers measured by the following measurement method is that of “fine cellulose fibers” corresponding to the raw material, but is substantially the same as that of the amidated “fine cellulose fiber composite”.

<Measuring method of average aspect ratio>
The average aspect ratio is calculated from the viscosity of a dispersion liquid prepared by adding water to cellulose fibers (mass concentration of cellulose fibers: 0.005 to 0.04 mass%). The viscosity of the dispersion is measured at 20 ° C. using a rheometer (MCR, DG42 (double cylinder), manufactured by PHYSICA). From the relationship between the mass concentration of the cellulose fibers in the dispersion and the specific viscosity of the dispersion with respect to water, the aspect ratio of the cellulose fibers is calculated by the following formula (1) to obtain the average aspect ratio. The following formula (1) is obtained from The Theory of Polymer Dynamics, M .; DOI and D.D. F. EDWARDS, CLARENDON PRESS · OXFORD, 1986 , P312 viscosity rigid-rod molecules according to equation (8.138), the relationship wherein the ^{Lb 2 × ρ = M / N} A, L is the fiber length, b is fiber width (The cross section of the cellulose fiber is a square), ρ is the concentration of the cellulose fiber (kg / m ³ ), M is the molecular weight, and N _A is the Avogadro number. In the viscosity formula (8.138), rigid rod-like molecules = cellulose fibers. In the following formula (1), η _SP is the specific viscosity, π is the circumference ratio, ln is the natural logarithm, P is the aspect ratio (L / b), γ = 0.8, ρ _S is the density of the dispersion medium ( kg / m ³ ), ρ ₀ represents the density of cellulose crystals (kg / m ³ ), and C represents the mass concentration of cellulose (C = ρ / ρ _S ).

In the fine cellulose fiber composite used in the present invention, the hydrocarbon group bonded via an amide bond is, for example, a hydrocarbon group having 1 carbon atom, or a saturated or unsaturated, straight chain having 2 to 30 carbon atoms. Or a branched hydrocarbon group is mentioned. As will be described later, these hydrocarbon groups are derived from a primary or secondary amine used as a raw material when producing a fine cellulose fiber composite. Specific examples include the following hydrocarbon groups.
-A hydrocarbon group having 1 carbon atom: a methyl group.
-C2-C30 saturated, linear hydrocarbon group: ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group, dodecyl group, octadecyl group, docosyl group An octacosanyl group.
-Unsaturated, linear hydrocarbon group having 2 to 30 carbon atoms: oleyl group, myristol group, palmitoleyl group, linoleyl group, linolenyl group, eicosanyl group.
A saturated branched hydrocarbon group having 2 to 30 carbon atoms: isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, t-pentyl group, isohexyl group, 2-hexyl group , Dimethylbutyl group, ethylbutyl group.

  In addition to the hydrocarbon group, alicyclic hydrocarbon groups such as cyclopentyl group and cyclohexyl group, and aromatic hydrocarbon groups such as benzyl group and phenyl group are also amide bonds in the fine cellulose fiber composite used in the present invention. It is preferably used as a hydrocarbon group bonded via

The average bond amount of hydrocarbon groups in the fine cellulose fiber composite (average bond amount per unit mass of the fine cellulose fiber composite) is preferably 0.1 mmol / g or more, more preferably 0.5 mmol / g or more, And preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1 mmol / g or less, more specifically preferably 0.1 to 3 mmol / g, more preferably 0.1 to 2 mmol / g. g, particularly preferably 0.5 to 1 mmol / g. The average bond amount of the hydrocarbon group is calculated by the following formula. In the following formula, “carboxy group content of fine cellulose fiber before introduction of hydrocarbon group” is measured by the above <Method for measuring carboxy group content of fine cellulose fiber>, and “fine cellulose fiber after introduction of hydrocarbon group” The “carboxy group content of the composite” is measured by the <Measurement method of carboxy group content of fine cellulose fiber composite> described later.
Bond amount of hydrocarbon group (mmol / g) = Carboxyl group content of fine cellulose fiber before introduction of hydrocarbon group (mmol / g) -Carboxy group content of fine cellulose fiber composite after introduction of hydrocarbon group (mmol) / G)

Moreover, the introduction rate of the hydrocarbon group to the fine cellulose fiber which is a raw material can be calculated from the average bond amount of the hydrocarbon group in the fine cellulose fiber composite by the following formula.
Introduction rate (%) of hydrocarbon groups = {average bond amount of hydrocarbon groups in the fine cellulose fiber composite (mmol / g) / carboxy group content of fine cellulose fibers before introduction of hydrocarbon groups (mmol / g) } × 100

  As described above, the fine cellulose fiber composite is obtained by amidating the carboxy group of the fine cellulose fiber having a carboxy group, and all of the carboxy groups in the fine cellulose fiber composite are amidated. Alternatively, the carboxy group may remain without being amidated. The carboxy group content of the fine cellulose fiber composite used in the present invention is preferably 0 mmol / g or more, more preferably 0.2 mmol / g or more, and preferably 2.9 mmol / g or less, more preferably 1 mmol / g. Hereinafter, particularly preferably 0.8 mmol / g or less, more specifically, preferably 0 to 2.9 mmol / g, more preferably 0 to 1 mmol / g, particularly preferably 0.2 to 0.8 mmol / g or less. It is. The carboxy group content of the fine cellulose fiber composite is measured as follows.

<Measuring method of carboxy group content of fine cellulose fiber composite>
Take a fine cellulose fiber composite with a dry mass of 0.5 g in a 100 mL beaker, add ion-exchanged water or a mixed solvent of methanol / water = 2/1 to make a total of 55 mL, and add 5 mL of 0.01 M sodium chloride aqueous solution to it. A dispersion is prepared, and the dispersion is stirred until the fine cellulose fiber composite is sufficiently dispersed. 0.1M hydrochloric acid was added to this dispersion to adjust the pH to 2.5-3, and 0.05M sodium hydroxide aqueous solution was added using an automatic titrator (trade name “AUT-50” manufactured by Toa DKK Corporation). The solution is dropped into the dispersion under the condition of a waiting time of 60 seconds, and the conductivity and pH values are measured every minute, and the measurement is continued until the pH is about 11 to obtain a conductivity curve. From this conductivity curve, the sodium hydroxide titration amount is obtained, and the carboxy group content of the fine cellulose fiber composite is calculated by the following formula.
Carboxy group content of fine cellulose fiber composite (mmol / g) = Sodium hydroxide titration × Sodium hydroxide aqueous solution concentration (0.05 M) / Mass of fine cellulose fiber composite (0.5 g)

The fine cellulose fiber composite used in the present invention can be produced, for example, by a production method having the following steps 1 and 2.
Step 1: A step of oxidizing a natural cellulose fiber in the presence of an N-oxyl compound to obtain a carboxy group-containing cellulose fiber.
Step 2: A step of reacting a carboxy group-containing cellulose fiber obtained through Step 1 with a primary or secondary amine having a hydrocarbon group to carry out an amidation reaction of the carboxy group of the cellulose fiber.

  In the step 1, first, a slurry in which natural cellulose fibers are dispersed in water is prepared. The slurry is obtained by adding about 10 to 1000 times (mass basis) of water to the natural cellulose fiber (absolute dry basis) as a raw material, and processing with a mixer or the like. Examples of natural cellulose fibers include wood pulp such as softwood pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; bacterial cellulose and the like. These 1 type can be used individually or in combination of 2 or more types. The natural cellulose fiber may be subjected to a treatment for increasing the surface area such as beating.

  Next, natural cellulose fibers are oxidized in water using an N-oxyl compound as an oxidation catalyst to obtain carboxy group-containing cellulose fibers. Examples of N-oxyl compounds that can be used as an oxidation catalyst for cellulose include TEMPO, 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO, and the like. A catalytic amount is sufficient for the addition of these N-oxyl compounds, and is usually in a range of 0.1 to 10% by mass with respect to natural cellulose fibers (absolute dry basis) used as a raw material.

  In the step 1, an oxidizing agent (for example, hypohalous acid or a salt thereof, a halogenous acid or a salt thereof, a perhalogen acid or a salt thereof, hydrogen peroxide, a perorganic acid, etc.) and a co-oxidant (for example, an odor In combination with an alkali metal bromide such as sodium bromide). As the oxidizing agent, alkali metal hypohalites such as sodium hypochlorite and sodium hypobromite are particularly preferable. The amount of the oxidizing agent used is usually in the range of about 1 to 100% by mass with respect to the natural cellulose fiber (absolute dry standard) used as a raw material. Moreover, the usage-amount of a co-oxidant is the range used as about 1-30 mass% normally with respect to the natural cellulose fiber (absolute dry reference | standard) used as a raw material.

  Moreover, in the said process 1, it is desirable to maintain the pH of a reaction liquid (the said slurry) in the range of 9-12 from a viewpoint of making an oxidation reaction advance efficiently. The temperature of the oxidation treatment (the temperature of the slurry) is arbitrary at 1 to 50 ° C., but the reaction is possible at room temperature, and no temperature control is required. The reaction time is preferably 1 to 240 minutes.

  In the step 1, the natural cellulose fiber is oxidized in the presence of an N-oxyl compound (TEMPO catalyst) in this manner, so that C6 in the glucopyranose ring, which is a constituent monomer unit of cellulose constituting the natural cellulose fiber. Only the primary hydroxyl group is selectively oxidized and oxidized to the carboxy group via the aldehyde to obtain the target carboxy group-containing cellulose fiber.

  If necessary, a purification step is performed after the completion of the step 1 and before the execution of the step 2 (amidation reaction), and carboxy contained in the slurry such as unreacted oxidant and various by-products. Impurities other than the group-containing cellulose fiber and water are removed. Since the carboxy group-containing cellulose fibers are usually not dispersed to the nanofiber unit at this stage, the purification process can be performed by a purification method that repeats washing and filtration, for example. Not. The purified carboxy group-containing cellulose fiber thus obtained is usually sent to the next step in a state of being impregnated with an appropriate amount of water, but may be a dried fiber or powder if necessary.

  Usually, after completion of Step 1, before carrying out Step 2 (amidation reaction) (after carrying out the purification step, after carrying out), carboxy group-containing cellulose fibers are dispersed in a solvent such as water. A refinement process is performed (a refinement process). By carrying out this refinement step, fine cellulose fibers each having an average fiber diameter and an average aspect ratio in the above ranges are obtained.

  In the micronization step, the solvent as a dispersion medium is usually preferably water, but water-soluble organic solvents (alcohols, ethers, ketones, etc.) may be used in addition to water depending on the purpose. These mixtures can also be suitably used. Examples of the disperser used in the miniaturization process include a disaggregator, a beater, a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short shaft extruder, a twin screw extruder, and an ultrasonic stirrer. A home juicer mixer or the like can be used. Further, the solid content concentration of the carboxy group-containing cellulose fiber in the refining treatment is preferably 50% by mass or less. When the solid content concentration exceeds 50% by mass, it is not preferable because extremely high energy is required for dispersion.

  As a form of the fine cellulose fiber obtained after the above-mentioned micronization step, the suspension is adjusted to a solid content concentration (visually colorless and transparent or opaque liquid), or a dried powder (however, cellulose as necessary) It is also a powder form in which fibers are aggregated and does not mean cellulose particles). In the case of a suspension, only water may be used as a dispersion medium, and a mixed solvent of water and other organic solvents (for example, alcohols such as ethanol), surfactants, acids, bases, etc. May be used.

  By such oxidation treatment of natural cellulose fibers (the step 1) and the refinement treatment (the refinement step), the hydroxyl group at the C6 position in the glucopyranose ring that is a constituent monomer unit of cellulose is selectively oxidized to a carboxy group. Thus, highly crystalline fine cellulose fibers having an average fiber diameter of preferably 200 nm or less and a carboxy group content of preferably 0.1 mmol / g or more and 3 mmol / g or less are obtained. This highly crystalline fine cellulose fiber has the same type I crystal structure as natural cellulose. This means that the fine cellulose fiber composite used in the present invention is a fiber obtained by subjecting a naturally-derived cellulose solid raw material having an I-type crystal structure to surface oxidation and being refined. In other words, natural cellulose fibers have a high-order solid structure in which fine fibers called microfibrils produced in the process of biosynthesis are bundled to form a high-order solid structure. The fine cellulose fibers can be obtained by weakening the hydrogen bond) by introduction of aldehyde groups or carboxy groups by the oxidation treatment, and further through the refinement treatment. And by adjusting the conditions for the oxidation treatment, the carboxy group content is increased or decreased within a predetermined range, the polarity is changed, or electrostatic repulsion of the carboxy group or the refinement treatment makes fine cellulose fibers. The average fiber diameter, average fiber length, average aspect ratio, etc. of (fine cellulose fiber composite) can be controlled.

  In the step 2, the primary cellulose or secondary amine having a hydrocarbon group is reacted with the fine cellulose fiber (carboxy group-containing cellulose fiber) obtained through the step 1, and the carboxy group of the fine cellulose fiber is reacted. An amidation reaction is performed. By such amidation reaction [dehydration condensation reaction between amine and carboxylic acid (fine cellulose fiber)], the carboxy group located at the C6 position in the glucopyranose ring of cellulose constituting the fine cellulose fiber is converted to amide (carboxylic amide ).

  The fine cellulose fiber (carboxy group-containing cellulose fiber) used as the starting material in Step 2 may be a sodium salt type having a sodium salt type carboxy group (COONa) or an acid type carboxy group (COOH). Although it may be an acid type, acid type fine cellulose fibers are preferred from the viewpoint of increasing the substitution rate of a carboxy group to an amide (carboxylic amide). As a method for converting sodium salt type fine cellulose fibers into acid type fine cellulose fibers, for example, a dispersion prepared by dispersing sodium salt type fine cellulose fibers in a solvent such as water is mixed with an acid such as hydrochloric acid. After adding an appropriate amount and stirring (for example, adjusting the pH of the dispersion after acid addition to 2.0 and stirring the dispersion for 12 hours), the fine cellulose fibers are mixed with an appropriate solvent (for example, acetone and water). The resulting mixture is washed and filtered, and acetone is added to the fine cellulose fiber after filtration and left for a certain period of time (for example, about 1 hour). The method of obtaining a cellulose fiber is mentioned.

  In the step 2, fine cellulose fibers (carboxy group-containing cellulose fibers) as a starting material are dispersed in an organic solvent, a predetermined amount of primary or secondary amine is added to the dispersion, and the mixture is stirred for a predetermined time. . The organic solvent in which the fine cellulose fibers are dispersed is not particularly limited as long as it is excellent in dispersibility of the fine cellulose fibers and does not inhibit the amidation reaction. For example, alcohols such as ethanol, isopropanol, and t-butyl alcohol Dimethylformamide, dimethyl sulfoxide, dimethylacetamide and the like, and one of these may be used alone, or two or more thereof may be used in combination, or a mixed solvent with water may be used. It is preferable to adjust the usage-amount of an organic solvent so that the density | concentration of the fine cellulose fiber in a dispersion liquid may be 0.1-50 mass%.

  The primary or secondary amine used in Step 2 constitutes a hydrocarbon group that is bonded through an amide bond in the fine cellulose fiber composite that is the production object. Examples of the primary amine include methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, octylamine, decylamine, dodecylamine, octadecylamine, oleylamine and the like. Examples of the secondary amine include dimethylamine, diethylamine, dibutylamine, dioctadecylamine and the like.

  In the step 2, a condensing agent may be added to the reaction system from the viewpoint of allowing the amide reaction to proceed efficiently. The condensing agent is preferably added after the amine is added to the fine cellulose fiber dispersion. As the condensing agent, a carbodiimide condensing agent, a triazine condensing agent, a phosphonium condensing agent, a benzotriazole condensing agent, an imidazole condensing agent, a polar group-containing halogenated carboxylic acid, and the like can be used. DMT-MM (4- (4,4-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride), EDC (1-ethyl-3- (3-dimethylaminopropyl) Carbodiimide hydrochloride), BOP (benzotriazol-1-yl-oxy-tris (dimethylamino) phosphonium hexafluorophosphate), PYBOP (benzotriazol-1-yl-oxy-tripyrrolidinophosphonium hexafluorophosphate), HBTU (O- (benzotriazol-1-yl)- , N, N ', N'- tetramethyluronium hexafluorophosphate), 1,2-benzisothiazolin-3-one, and the like.

  In step 2, the temperature of the reaction system (reaction temperature of the amidation reaction) is preferably 20 to 80 ° C., and the reaction time is preferably 1 to 24 hours. After completion of step 2, the reaction system is washed and filtered according to a conventional method to remove impurities such as unreacted substances and various by-products. In this way, a fine cellulose fiber composite in which hydrocarbon groups are bonded to fine cellulose fibers via amide bonds is obtained. The fine cellulose fiber composite may be a swollen gel impregnated with a solvent (for example, acetone) used at the time of washing, or may be a dried fiber or powder.

  In the resin composition of the present invention, the resin used in combination with the fine cellulose fiber composite is selected from the group consisting of polyolefin resins, polyvinyl chloride resins, polyamide resins and polycarbonate resins. These resins are all thermoplastic resins, and can be used singly or in combination of two or more.

  Examples of the polyolefin resin used in the present invention include polyethylene and polypropylene, and more specifically, for example, low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene, modified polyethylene resin, and modified polypropylene. Examples thereof include resins.

  Examples of the polyvinyl chloride resin used in the present invention include soft polyvinyl chloride and hard polyvinyl chloride.

  Examples of the polyamide-based resin used in the present invention include 6 nylon and 66 nylon.

  Examples of the polycarbonate resin used in the present invention include general polycarbonates using bisphenol A as a raw material, and special polycarbonates using siloxane as a raw material.

  As the resin used in combination with the fine cellulose fiber composite, in addition to the above thermoplastic resin, for example, a polyacrylic resin such as polymethyl methacrylate, a vinyl resin such as polystyrene, or a fluorine resin such as polyvinylidene fluoride. To provide a resin composition that has the same effect as the present invention even when a resin, a silicone resin, a polyimide resin, or the like is used, but has a practically sufficient mechanical strength and is less colored. Can do.

  Selection of resin is suitably selected according to the specific use etc. of the resin composition of this invention obtained by mix | blending a fine cellulose fiber composite with this. In addition, since the fine cellulose fiber composite usually has various characteristics depending on the type of amide (carboxylic amide) introduced into the glucopyranose ring of cellulose (preferably C6 position of the glucopyranose ring) constituting the fine cellulose fiber composite, It is desirable to select a fine cellulose fiber composite suitable for the resin used so that the mechanical strength can be effectively improved while suppressing the coloring of the resin as much as possible.

  For example, when high-density polyethylene is used as the resin, the fine cellulose fiber composite used together preferably has an octadecylamide group (C number 18).

  The content of the fine cellulose fiber composite in the resin composition of the present invention can be appropriately set according to the type of resin used from the viewpoint of balance between improvement in mechanical strength of the resin and prevention of coloring of the resin. . Generally, from the viewpoint of improving the mechanical strength, it is preferable that the content of the fine cellulose fiber composite is large. However, if the content of the fine cellulose fiber composite is too large, the resin contained together with the fine cellulose fiber is colored. Then, there is a possibility that the resin composition will exhibit an unintended color. Although the cause of such resin coloring is not clear, it is caused by the thermal decomposition of the fine cellulose fiber composite during the melt-kneading of the resin and the fine cellulose fiber composite in producing the resin composition. Inferred. From such a viewpoint, the content of the fine cellulose fiber composite in the resin composition of the present invention is preferably 0.01% by mass or more, more preferably 0.1% by mass with respect to the total mass of the resin composition. Above, and preferably 50% by mass or less, more preferably 10% by mass or less, more specifically preferably 0.01 to 50% by mass, and more preferably 0.1 to 10% by mass. In particular, when polyolefin is used as the resin, the content of the fine cellulose fiber composite is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 5% by mass or less, more specifically. Specifically, it is preferably 0.01 to 5% by mass, more preferably 0.1 to 5% by mass.

  However, the fine cellulose fiber composite used in the present invention (amidated fine cellulose fiber) has high thermal stability as compared with conventional modified cellulose fibers of this type as described in Patent Documents 1 to 3, Since it is difficult to cause thermal decomposition during melt kneading with the resin, in combination with the excellent dispersibility in the resin and the ability to effectively improve the mechanical strength of the resin with a relatively small content, Less likely to cause coloring problems.

  On the other hand, the content of the resin in the resin composition of the present invention is preferably 50% by mass or more, more preferably 90% by mass or more, and preferably 99.99% by mass or less, with respect to the total mass of the resin composition. More preferably, it is 99.90 mass% or less, More specifically, Preferably it is 50-99.99 mass%, More preferably, it is 90-99.90 mass%.

  The resin composition of the present invention can increase the compatibility between the fine cellulose fiber composite and the resin, if necessary, other components other than the fine cellulose fiber composite and the resin, for example, and can improve the adhesion between the two components. An adhesive may be included. Examples of such an adhesive include adhesive resins such as polypropylene graft-modified with maleic anhydride (MA-g-PP), polyethylene graft-modified with maleic anhydride (MA-g-PE), and epoxy-modified polyethylene. Can be used. The content of the adhesive is preferably 1 to 10% by mass with respect to the total mass of the resin composition. Moreover, the resin composition of this invention may contain dispersing agents, such as a crosslinking agent, clay mineral, surfactant, a coloring agent, an antistatic agent, etc. as components other than an adhesive agent.

  The resin composition of the present invention can be produced, for example, by a production method comprising a step of mixing a fine cellulose fiber composite and a resin to obtain a uniform mixture, and molding the uniform mixture into an arbitrary shape.

  As the form of the fine cellulose fiber composite used as the raw material of the resin composition of the present invention, in consideration of the resin used together with the fine cellulose fiber composite, the apparatus used for kneading, etc., powder form (however, the cellulose fibers are aggregated) Powdery powder, which does not mean cellulose particles), suspension (visually colorless and transparent or opaque liquid), and the like. In particular, when a powdery fine cellulose fiber composite is used as a raw material, the fine cellulose fiber composite is easily uniformly dispersed in the resin composition, and the fine cellulose fiber composite has a relatively small content (content of 10% by mass or less). Use of the body provides practically sufficient mechanical strength.

  Examples of the powdered fine cellulose fiber composite include, for example, a dried product obtained by directly drying an aqueous dispersion of the fine cellulose fiber composite; a powder obtained by pulverizing the dried product by mechanical treatment; and an aqueous dispersion of the fine cellulose fiber composite. A liquid is mixed with a non-aqueous solvent such as alcohol to aggregate the fiber composite, and the aggregate is dried; an undried product of the aggregate; an aqueous dispersion of the fine cellulose fiber composite is a known spray. What was pulverized by the dry method; What was pulverized the water dispersion of the fine cellulose fiber composite by the well-known freeze-dry method, etc. are mentioned. The spray drying method is a method in which an aqueous dispersion of the fine cellulose fiber composite is sprayed in the air and dried.

  As the suspension-like fine cellulose fiber composite, an aqueous dispersion of the fine cellulose fiber composite can be used as it is, or a powdery fine cellulose fiber composite is dispersed in an arbitrary medium. Can also be used. Such a medium is appropriately selected depending on a resin to be mixed, a mixing and molding method described later, and water, alcohol, or the like can be used, for example.

  In the case where the resin used in combination with the fine cellulose fiber composite is a thermoplastic resin, for example, the fine cellulose fiber composite is added to the heated and molten resin, and the resin is maintained in the molten state. The resin composition of the present invention can be produced by a method of kneading these together and forming a uniform mixture thus obtained (hereinafter also referred to as a melt kneading method). In that case, as a kneading apparatus, for example, a known apparatus such as a single-shaft kneading extruder, a twin-screw kneading extruder, or a pressure kneader can be used. For example, by adding a powdery fine cellulose fiber composite into a molten thermoplastic resin, kneading them using a biaxial kneader to obtain resin pellets, and heating and compressing the resin pellets A sheet-like resin composition is obtained. Alternatively, using a known plastic molding method, specifically injection molding, casting, extrusion molding, blow molding, stretch molding, foam molding, etc., a resin composition having a block shape or other three-dimensional shape is obtained. Can do.

  A uniform mixture of a fine cellulose fiber composite and a resin is a liquid obtained by dispersing a fine cellulose fiber composite in a solvent such as water to obtain a slurry, and dissolving or dispersing the resin or resin in an appropriate solvent in the slurry. It can also be obtained by the method of adding. As the solvent in this homogeneous mixture (slurry), water is usually preferable, but water-soluble organic solvents (alcohols, ethers, ketones, etc.) may be used in addition to water depending on the purpose. A mixture of these solvents can also be suitably used. Further, the solid content concentration of the uniform mixture is preferably 30% by mass or less from the viewpoint of facilitating dispersion. Examples of the disperser used for preparing the slurry include a disaggregator, a beater, a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short shaft extruder, a twin screw extruder, and an ultrasonic stirrer. A home juicer mixer or the like can be used.

  Moreover, the casting method is mentioned as a manufacturing method of resin compositions other than the melt kneading method. The casting method is a method in which a mixed fluid in which a fine cellulose fiber composite and a resin are dispersed or dissolved in a solvent is cast-coated on a substrate, a solvent is removed to obtain a film, and the film is subjected to hot pressing. Thus, a thin film resin composition is obtained. In the casting method, as a method for removing the solvent from the mixed fluid applied on the base material, for example, a liquid-permeable base material (for example, a porous material having a large number of liquid-permeable holes penetrating in the thickness direction). A method using a conductive substrate). In this method, by applying the mixed fluid on the liquid-permeable substrate, the solvent in the mixed fluid is removed through the porous substrate, and the solid content (fine cellulose fiber composite and resin) is removed. Is scraped onto the porous substrate. Another solvent removal method includes a method in which the mixed fluid is cast-coated on a substrate and then the mixed fluid is dried by a drying method such as natural drying or hot air drying. Moreover, in the casting method, the hot pressing performed on the film obtained after removing the solvent can be performed using a known apparatus such as a pressing type or a rotary type using a metal plate, for example.

  Moreover, the resin composition of the present invention can also be produced by an impregnation method. That is, the resin composition of the present invention may be obtained by impregnating a fiber assembly mainly composed of a fine cellulose fiber composite with a liquid containing a resin. This fiber assembly is a sheet-like or desired three-dimensional fiber assembly that does not substantially contain the resin used in the resin composition, and is produced by, for example, a known wet papermaking method or pulp mold forming method. be able to. In the method for producing a resin composition using the impregnation method, a fiber aggregate mainly composed of a fine cellulose fiber composite is immersed in a liquid containing a resin, and the liquid is infiltrated into the fiber aggregate. The liquid containing the resin can be obtained by dispersing or dissolving the resin in an appropriate solvent such as water. After immersing the fiber assembly in a liquid containing resin, the fiber assembly is dried by a drying method such as natural drying or hot air drying to obtain a resin composition having a desired shape.

  The resin composition of the present invention can be molded into an arbitrary shape, and is provided as a thin object such as a film or a sheet, a block shape such as a rectangular parallelepiped or a cube, or other three-dimensional shapes. For example, when a thin resin composition is used, the thickness is not particularly limited, but is usually 0.05 to 50 mm.

  The resin composition of the present invention can also be used as an additive for resin modification that can be added to a resin separate from the resin composition and improved in properties such as mechanical strength. A resin-modifying additive-containing resin obtained by blending this resin-modifying additive with a resin is also included in the resin composition of the present invention.

  Below, the suitable manufacturing method of the additive for resin modification which is an example of the resin composition of this invention is demonstrated. This production method comprises (a) preparing an emulsion (a homogeneous mixture of a fine cellulose fiber composite and a resin) containing a fine cellulose fiber composite, resin particles, and a liquid medium, and then (b) drying the emulsion by drying. A step of removing the liquid medium.

  There are no particular restrictions on the shape of the resin modifying additive and the resin particles used as its raw material, and various shapes can be used. From the viewpoint of successfully producing resin particles in this production method. It is preferable to use substantially spherical particles. Moreover, the resin particles used as a raw material may be previously dispersed in a dispersion medium and emulsified, or may be in a powder form. When powdered resin particles are used, a surfactant, a dispersant or the like may be used in order to successfully make the resin particles into an emulsion.

  In the step (a), water is usually used as the liquid medium used for mixing the fine cellulose fiber composite and the resin particles, but in addition to that, a medium in which the fine cellulose fiber composite can be dispersed. Examples thereof include a water-insoluble organic medium, a water-soluble organic medium, a water-soluble organic medium, or a mixed medium of these with water. What kind of medium is used may be appropriately determined according to the dispersibility of the resin particles. As the water-insoluble organic medium, for example, toluene, chloroform, ethyl acetate, hexane or the like can be used. These can be used alone or in combination of two or more. As the water-soluble organic medium, for example, ethanol, methanol, isopropanol, t-butyl alcohol, acetone, N-methyl-2-pyrrolidone, tetrahydrofuran and the like can be used. These can be used alone or in combination of two or more.

  In the step (a), an emulsion can be prepared by mixing, for example, a fine cellulose fiber composite, resin particles, and a liquid medium. From the viewpoint of ease of preparation of the emulsion, it is advantageous to prepare the emulsion by mixing the resin particles in the emulsion state (that is, a resin emulsion dispersed in a liquid medium in advance) and a fine cellulose fiber composite. . As the resin emulsion, for example, a water emulsion, an emulsion of a water-insoluble organic medium, an emulsion of a water-soluble organic medium, or an emulsion of water and a water-soluble organic medium can be used. In consideration of safety and the like, it is preferable to use a water emulsion and an emulsion of water and a water-soluble organic medium. Whatever the resin emulsion of the medium is used, the concentration of the resin particles in the resin emulsion can be 1 to 80% by mass, particularly 5 to 30% by mass, so that the resin particles can be stably dispersed. From the viewpoints of efficiency and efficiency at the time of drying described later.

  In the step (a), an emulsion is obtained by mixing powdery resin particles (that is, a dry resin powder that has not been previously dispersed in a liquid medium) and a fine cellulose fiber composite. Can also be prepared. In this case, even if the resin powder is inherently difficult to disperse in the liquid medium, the fine cellulose fiber composite to be used in combination becomes a dispersant, so that an emulsion can be prepared. If necessary, an emulsion can be prepared using a dispersant other than a surfactant or a fine cellulose fiber composite.

  By mixing the resin emulsion and the dispersion of the fine cellulose fiber composite, a desired fine cellulose fiber composite / resin particle emulsion (a uniform mixture of the fine cellulose fiber composite and the resin particles) is obtained. . The concentration of the fine cellulose fiber composite contained in this emulsion is preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and is preferably 40% by mass or less, particularly preferably 5% by mass or less. . The concentration of the resin particles is preferably 0.1% by mass or more, more preferably 50% by mass or less, and particularly preferably 10% by mass or less. In addition to the fine cellulose fiber composite and resin particles, the emulsion contains a crosslinking agent, a clay mineral, a dispersant such as a surfactant, a colorant, an antistatic agent and the like as necessary. Also good.

  In the step (b), the liquid medium is removed from the fine cellulose fiber composite / resin particle emulsion thus obtained, and the desired additive for resin modification (as the resin composition of the present invention is used). One form). The liquid medium is removed by drying. Drying of the liquid medium may be natural drying or heat drying. When using these drying methods, it is preferable from the viewpoint of drying efficiency that the emulsion is cast (cast) and dried. Other drying methods include freeze drying and spray drying. In spray drying, the emulsion may be ejected from a nozzle to form fine droplets, and then heated and dried in convection air.

  The additive for resin modification thus obtained can be used as, for example, a chip-shaped master batch. By adding this master batch to a thermoplastic resin using an extruder, melt-kneading, and melt-molding, it is possible to obtain a resin-modifying additive-containing resin that is one type of the resin composition of the present invention. it can. As this thermoplastic resin, for example, the same resins as various resins constituting the resin particles described above can be used. The thermoplastic resin may be the same type as the resin constituting the resin particles, or may be a different type. If the same kind of resin is used, the dispersibility of the fine cellulose fiber composite in the intended resin composition can be easily increased. When different types of resins are used, it is preferable to employ a combination of compatible resins.

  The resin composition of the present invention contains a fine cellulose fiber composite (amidated fine cellulose fiber), so that mechanical strength such as tensile elastic modulus is used together with the fine cellulose fiber composite (base polymer). ). The reason is that the fine cellulose fiber composite is highly dispersed in the resin composition. Further, the resin composition of the present invention effectively suppresses the coloring of the resin used in combination with the fine cellulose fiber composite, and therefore exhibits the original color of the resin or a color very close to it, and is versatile. high. The reason why the coloring of the resin is suppressed is that, in addition to the fine cellulose fiber composite being highly dispersed in the resin composition, the fine cellulose fiber composite is excellent in heat resistance and produces a resin composition. This is presumably due to the fact that thermal decomposition hardly occurs at the time of melt kneading with the resin.

  The resin composition of the present invention can be used for developing applications for various daily-use packaging films (pouches, pillows), sheets (blister packs), molded members (bottles, caps, spoons, toothbrush handles, etc.), especially mechanical It can be suitably used for applications in which strength is important (for example, automobiles, information appliances, etc.).

  In relation to the above-described embodiment, the present invention further discloses the following resin composition and production method.

<1> Selected from the group consisting of a fine cellulose fiber composite in which a hydrocarbon group is bonded to a fine cellulose fiber via an amide bond, and a polyolefin resin, a polyvinyl chloride resin, a polyamide resin, and a polycarbonate resin. The resin composition containing 1 or more types of resin.

<2> The resin according to <1>, wherein the hydrocarbon group is a hydrocarbon group having 1 carbon atom, or a saturated or unsaturated, linear or branched hydrocarbon group having 2 to 30 carbon atoms. Composition.
<3> The average bond amount of the hydrocarbon group is preferably 0.1 mmol / g or more, more preferably 0.5 mmol / g or more, and preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly <1> preferably 1 mmol / g or less, more specifically preferably 0.1 to 3 mmol / g, more preferably 0.1 to 2 mmol / g, and particularly preferably 0.5 to 1 mmol / g. Or the resin composition as described in <2>.
<4> The carboxy group content of the fine cellulose fiber composite is preferably 0 mmol / g or more, more preferably 0.2 mmol / g or more, and preferably 2.9 mmol / g or less, more preferably 1 mmol / g. In the following, it is particularly preferably 0.8 mmol / g or less, more specifically, preferably 0 to 2.9 mmol / g, more preferably 0 to 1 mmol / g, and particularly preferably 0.2 to 0.8 mmol / g. The resin composition according to any one of <1> to <3>.
<5> The resin composition according to any one of <1> to <4>, wherein the polyolefin resin is one or more selected from the group consisting of polyethylene and polypropylene.

<6> The average fiber diameter of the fine cellulose fiber composite is preferably 1 nm or more, and preferably 200 nm or less, more preferably 100 nm or less, particularly preferably 50 nm or less, more specifically preferably 1 to 200 nm. The resin composition according to any one of <1> to <5>, more preferably 1 to 100 nm, particularly preferably 1 to 50 nm.
<7> The carboxy group content of the fine cellulose fiber is preferably 0.1 mmol / g or more, more preferably 0.4 mmol / g or more, particularly preferably 0.6 mmol / g or more, and preferably 3 mmol / g. Hereinafter, more preferably 2 mmol / g or less, particularly preferably 1.8 mmol / g or less, more specifically preferably 0.1 to 3 mmol / g, more preferably 0.4 to 2 mmol / g, particularly The resin composition according to any one of <1> to <6>, preferably 0.6 to 1.8 mmol / g.
<8> The average aspect ratio of the fine cellulose fibers is preferably 10 or more, more preferably 50 or more, particularly preferably 100 or more, and preferably 1000 or less, more preferably 500 or less, particularly preferably 350 or less. Specifically, the resin composition according to any one of <1> to <7>, preferably 10 to 1000, more preferably 50 to 500, and particularly preferably 100 to 350.
<9> The hydrocarbon group is methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group, dodecyl group, octadecyl group, docosyl group, octacosanyl group, oleyl group , Myristol group, palmitoleyl group, linoleyl group, linolenyl group, eicosanyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, t-pentyl group, isohexyl group, 2-hexyl group, The resin composition according to any one of <1> to <8>, which is at least one selected from the group consisting of a dimethylbutyl group, an ethylbutyl group, a cyclopentyl group, a cyclohexyl group, a benzyl group, and a phenyl group.

<10> The resin composition according to any one of <1> to <9>, wherein the fine cellulose fiber composite is produced through the following steps 1 and 2.
Step 1: A step of oxidizing a natural cellulose fiber in the presence of an N-oxyl compound to obtain a carboxy group-containing cellulose fiber.
Step 2: A step of reacting a carboxy group-containing cellulose fiber obtained through Step 1 with a primary or secondary amine having a hydrocarbon group to carry out an amidation reaction of the carboxy group of the cellulose fiber.

<11> After the completion of the step 1 and before the execution of the step 2, the carboxy group-containing cellulose fibers obtained in the step 1 are dispersed in a solvent, and the carboxy group-containing cellulose fibers are subjected to a fine treatment. The resin composition according to <10>, wherein the step exists.

<12> The N-oxyl compound is 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl, 4 One selected from the group consisting of -carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl and 4-phosphonooxy-2,2,6,6-tetramethylpiperidine-1-oxyl The resin composition as described in <10> or <11> above.
<13> The primary amine having a hydrocarbon group is selected from the group consisting of methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, octylamine, decylamine, dodecylamine, octadecylamine and oleylamine. The resin composition according to any one of <10> to <12>, which is one or more.
<14> The secondary amine having a hydrocarbon group is one or more selected from the group consisting of dimethylamine, diethylamine, dibutylamine, and dioctadecylamine, and any one of <10> to <13>. The resin composition described in 1.

<15> The polyolefin resin is at least one selected from the group consisting of low density polyethylene, high density polyethylene, polypropylene, modified polyethylene resin, and modified polypropylene resin, and any one of <1> to <14>. The resin composition described in 1.
<16> The resin composition according to any one of <1> to <15>, wherein the polyvinyl chloride resin is at least one selected from the group consisting of soft polyvinyl chloride and hard polyvinyl chloride. .
<17> The resin composition according to any one of <1> to <16>, wherein the polyamide-based resin is at least one selected from the group consisting of 6 nylon and 66 nylon.
<18> The polycarbonate resin is at least one selected from the group consisting of a general polycarbonate using bisphenol A as a raw material and a special polycarbonate using siloxane as a raw material, and any one of the above <1> to <17> The resin composition described in 1.

<19> The content of the fine cellulose fiber composite is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 50% by mass with respect to the total mass of the resin composition. % Or less, more preferably 10% by mass or less, more specifically, preferably 0.01 to 50% by mass, more preferably 0.1 to 10% by mass, any one of <1> to <18> The resin composition as described in 1.
<20> The content of the resin is preferably 50% by mass or more, more preferably 90% by mass or more, and preferably 99.99% by mass or less, more preferably, with respect to the total mass of the resin composition. 99.90% by mass or less, more specifically, preferably 50 to 99.99% by mass, more preferably 90 to 99.90% by mass, according to any one of <1> to <19> above. Resin composition.

<21> The method for producing a resin composition according to any one of <1> to <20>, wherein the fine cellulose fiber composite and the resin are mixed to obtain a uniform mixture, and the uniform mixture is obtained. The manufacturing method of the resin composition which has the process shape | molded in arbitrary shapes.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

[Example 1]
(1) Production of Fine Cellulose Fiber Coniferous bleached kraft pulp (manufacturer: Fletcher Challenge Canada, trade name “Machenzie”, CSF 650 ml) was used as natural cellulose fiber. As TEMPO, a commercial product (manufacturer: ALDRICH, Free radical, 98% by mass) was used. A commercial product (manufacturer: Wako Pure Chemical Industries, Ltd.) was used as sodium hypochlorite. A commercial product (manufacturer: Wako Pure Chemical Industries, Ltd.) was used as sodium bromide. First, 100 g of bleached kraft pulp fiber of coniferous trees was sufficiently stirred with 9900 g of ion-exchanged water, and then TEMPO 1.25% by mass, sodium bromide 12.5% by mass, sodium hypochlorite 28. 4% by weight was added in this order. Using a pH stud, 0.5M sodium hydroxide was added dropwise to maintain the pH at 10.5, and an oxidation reaction was performed. After the oxidation was performed for 120 minutes, dropping was stopped to obtain a carboxy group-containing cellulose fiber. The carboxy group-containing cellulose fiber was sufficiently washed with ion-exchanged water, and then dehydrated. Thereafter, 100 g of the obtained carboxy group-containing cellulose fiber is dispersed in 7592 g of ion-exchanged water, and treated twice using a high-pressure homogenizer (Starburst Lab HJP-25005, manufactured by Sugino Machine Co., Ltd.) at a discharge pressure of 245 MPa. Went. By the operation, the fiber was refined to obtain a dispersion of fine cellulose fibers. The solid content concentration of the dispersion was 1.3% by mass. This fine cellulose fiber had an average fiber diameter of 3.3 nm, an average aspect ratio of 200, and a carboxy group content of 1.4 mmol / g.

(2) Production of Fine Cellulose Fiber Composite A dispersion of 4088.75 g of the fine cellulose fiber (solid content concentration: 1.3% by mass) and 4085 g of ion-exchanged water are added to a beaker to obtain a solid content concentration of 0.5% by mass. And then stirred at room temperature for 3 hours with a mechanical stirrer. Subsequently, 245 g of a 1M hydrochloric acid aqueous solution was charged into the fine cellulose fiber dispersion and reacted at room temperature overnight. After completion of the reaction, the solution was reprecipitated with acetone, filtered, and then washed with acetone / ion exchange water to remove hydrochloric acid and salts. Finally, acetone was added and filtered to obtain acetone-containing acid-type fine cellulose fibers (solid content concentration 5.0% by mass) in a state where fine cellulose fibers were swollen in acetone.

  Next, 509.16 g of the acetone-containing acid type fine cellulose fiber (the solid content concentration was adjusted from 5.0 mass% to 4.4 mass%) was charged into a 4-neck round bottom flask equipped with a mechanical stirrer and a reflux tube. Then, 5000 g of isopropyl alcohol was added to obtain an acetone-containing acid-type fine cellulose fiber dispersion having a solid concentration of 0.5% by mass, and the mixture was stirred with a magnetic stirrer at room temperature for 1 hour. Subsequently, 5.45 g of propylamine (corresponding to 3 mol of amine groups with respect to 1 mol of carboxy groups of fine cellulose fibers) and 26.38 g of DMT-MM were charged and dissolved, and then reacted at room temperature overnight. After completion of the reaction, the mixture was filtered, and then washed with methanol / ion exchange water to remove unreacted propylamine and DMT-MM. Finally, acetone was added and filtered to prepare a fine cellulose fiber composite in which propyl groups were bonded to the fine cellulose fiber via an amide bond.

(3) Preparation of resin particles A polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd., solid content concentration: 25% by mass) was used.

(4) Preparation of fine cellulose fiber composite / emulsion of resin particles The fine cellulose fiber composite obtained in (2) above was made into a dispersion having a solid concentration of 0.5% with ion-exchanged water, and 100 g of the dispersion was obtained. Then, 8 g of the polyethylene resin emulsion prepared in the above (3) was poured into a beaker and mixed for 30 minutes using a magnetic stirrer. Thus, the intended emulsion was obtained.

(5) Production of resin-modifying additive The emulsion obtained in (4) was freeze-dried to obtain a resin-modifying additive. The cellulose content of the fine cellulose fiber composite in the obtained resin modifying additive was 20% by mass, and the content of polyethylene derived from the polyethylene resin emulsion was 80% by mass.

(6) Production of resin composition The resin-modifying additive obtained in (5) above and a high-density polyethylene resin (HDPE, trade name: Novatec HD HB338RE, manufactured by Nippon Polyethylene Co., Ltd.) Melt kneading was performed using a plast mill, manufactured by Toyo Seiki Co., Ltd. To 28 parts by mass of HDPE, 2.4 parts by mass of the obtained resin modifying additive and 2 parts by mass of an adhesive resin (Adtex DH4200, manufactured by Nippon Polyethylene Co., Ltd.) as an adhesive are added at 150 ° C. The mixture was kneaded for 10 minutes at a rotation speed of 70 rpm. The obtained kneaded material was hot-pressed at 160 ° C., 0.5 MPa for 3 minutes, and 20 MPa for 1 minute using a press machine (Lab Press P2-30T, manufactured by Toyo Seiki Co., Ltd.), and further at 23 ° C., 0 Cooled and pressed at 5 MPa for 1 minute. As a result, a sheet-like resin composition having a thickness of 0.5 mm was obtained.

[Example 2]
In a four-necked round bottom flask equipped with a mechanical stirrer and a reflux tube, 93.02 g of acetone-containing acid-type fine cellulose fibers obtained in Example 1 (the solid content concentration was adjusted from 5.0% by mass to 4.4% by mass) Was added, and 800 g of t-butyl alcohol was added to obtain an acetone-containing acid-type fine cellulose fiber dispersion having a solid content concentration of 0.5% by mass, followed by stirring at room temperature for 1 hour. Subsequently, 1.46 g of hexylamine (corresponding to 3 mol of amine group with respect to 1 mol of carboxy group of fine cellulose fiber) and 4.12 g of DMT-MM were charged and dissolved, and then reacted at 60 ° C. for 4 hours. Thereafter, 1.46 g of hexylamine (corresponding to 3 mol of amine group with respect to 1 mol of carboxy group of fine cellulose fiber) and 4.12 g of DMT-MM were added and reacted at 60 ° C. for 4 hours. After completion of the reaction, the mixture was filtered and then washed with ethanol / ion exchange water to remove unreacted hexylamine and DMT-MM. Finally, acetone was added and filtered to prepare a fine cellulose fiber composite in which hexyl groups were bonded to fine cellulose fibers via amide bonds. Using this fine cellulose fiber composite, a sheet-shaped resin composition having a thickness of 0.5 mm was obtained according to the procedures (3) to (6) of Example 1.

Example 3
In a four-necked round bottom flask equipped with a mechanical stirrer and a reflux tube, 79.29 g of acetone-containing acid-type fine cellulose fibers obtained in Example 1 (the solid content concentration was adjusted from 5.0% by mass to 3.3% by mass) And 800 g of isopropyl alcohol was added to obtain an acetone-containing acid-type fine cellulose fiber dispersion having a solid content concentration of 0.3% by mass, followed by stirring at room temperature for 1 hour. Subsequently, 1.19 g of dodecylamine (corresponding to 2 mol of amine group with respect to 1 mol of carboxy group of fine cellulose fiber) and 1.78 g of DMT-MM were charged and dissolved, and then reacted at 50 ° C. for 4 hours. After completion of the reaction, the mixture was filtered and then washed with ethanol / ion exchange water to remove unreacted dodecylamine and DMT-MM. Finally, acetone was added and filtered to prepare a fine cellulose fiber composite in which dodecyl groups were bonded to fine cellulose fibers via amide bonds. Using this fine cellulose fiber composite, a sheet-like resin composition having a thickness of 0.5 mm was obtained according to the procedures (3) to (6) of Example 1. In the “(6) Production of resin composition”, 0.8 part by mass of the resin modifying additive was used with respect to 28 parts by mass of HDPE.

Example 4
Acetone-containing acid-type fine cellulose fibers obtained in Example 1 were prepared in a four-necked round bottom flask equipped with a mechanical stirrer and a reflux tube (the solid content concentration was adjusted from 5.0% by mass to 4.4% by mass). 488.80 g was charged and 4800 g of t-butyl alcohol was added to obtain an acetone-containing acid-type fine cellulose fiber dispersion having a solid content concentration of 0.5% by mass, followed by stirring at room temperature for 1 hour. Subsequently, 17.50 g of octadecylamine (corresponding to 2 mol of amine group with respect to 1 mol of carboxy group of fine cellulose fiber) and 17.97 g of DMT-MM were charged, dissolution was confirmed, and reaction was performed at 55 ° C. for 6 hours. After completion of the reaction, the mixture was filtered and then washed with methanol / ion exchange water to remove unreacted octadecylamine and DMT-MM. Finally, acetone was added and filtered to prepare a fine cellulose fiber composite in which octadecyl groups were bonded to the fine cellulose fiber via an amide bond. Using this fine cellulose fiber composite, a sheet-like resin composition having a thickness of 0.5 mm was obtained according to the procedures (3) to (6) of Example 1. In the “(6) Production of resin composition”, 0.8 part by mass of the resin modifying additive was used with respect to 28 parts by mass of HDPE.

Example 5
The fine cellulose fiber composite used in Example 1 was made into a dispersion having a solid concentration of 0.5% by mass with ion-exchanged water, and 100 g of this dispersion and polyvinyl chloride resin (Vinyl Blanc HD-057, Nissin Chemical Industry Co., Ltd.) 190.4 g of solid product concentration 13 mass%), polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Co., Ltd., solid content concentration 25 mass%) 99 g was poured into a beaker and 30 using a magnetic stirrer. Mix for minutes to obtain an emulsion. 40 g of this emulsion was poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm and dried in an environment of 23 ° C. and 50% RH for 1 week to obtain a dried film. This dried product was cooled and pressed at 200 ° C. and 0.5 MPa for 3 minutes and further at 23 ° C. and 0.5 MPa for 1 minute using a press machine (Lab Press P2-30T, manufactured by Toyo Seiki Co., Ltd.). As a result, a sheet-shaped resin composition having a thickness of 0.1 mm was obtained.

Example 6
The fine cellulose fiber composite used in Example 1 was made into a dispersion having a solid concentration of 0.5% by mass with ion-exchanged water, and 100 g of the dispersion and a polyamide resin (Separjon PA200, manufactured by Sumitomo Seika Co., Ltd., solid concentration) 40 mass%) 61.9 g, polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd., solid content concentration 40 mass%) 99 g is poured into a beaker and mixed for 30 minutes using a magnetic stirrer. Got. 40 g of this emulsion was poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm and dried in an environment of 23 ° C. and 50% RH for 1 week to obtain a dried film. This dried product was cooled and pressed at 180 ° C. and 0.5 MPa for 3 minutes and further at 23 ° C. and 0.5 MPa for 1 minute using a press machine (Lab Press P2-30T, manufactured by Toyo Seiki Co., Ltd.). As a result, a sheet-shaped resin composition having a thickness of 0.1 mm was obtained.

Example 7
The fine cellulose fiber composite used in Example 1 was made into a dispersion having a solid concentration of 0.5% by mass with ion-exchanged water, and 100 g of the dispersion and polycarbonate resin (S-3000FN, manufactured by Mitsubishi Engineering Plastics Co., Ltd., powder) 24.8 g, polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd., solid content concentration 40% by mass) 99 g is poured into a beaker and mixed for 30 minutes using a magnetic stirrer to obtain an emulsion. It was. 40 g of this emulsion was poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm and dried in an environment of 23 ° C. and 50% RH for 1 week to obtain a dried film. This dried product was cooled and pressed at 200 ° C. and 0.5 MPa for 3 minutes and further at 23 ° C. and 0.5 MPa for 1 minute using a press machine (Lab Press P2-30T, manufactured by Toyo Seiki Co., Ltd.). As a result, a sheet-shaped resin composition having a thickness of 0.1 mm was obtained.

[Comparative Example 1]
Without using the fine cellulose fiber composite, only the polyethylene resin emulsion was lyophilized in the same manner as in Example 1 to obtain a dried product. Using this dried product, a sheet-shaped resin composition having a thickness of 0.5 mm was obtained in accordance with “(6) Production of resin composition” in Example 1. In the “(6) Production of resin composition”, 1.9 parts by mass of the dried product was used with respect to 28 parts by mass of HDPE.

[Comparative Example 2]
The fine cellulose fiber used in Example 1 was used as it was without amidation, and freeze-dried in the same manner as in Example 1 to obtain a dried product. Using this dried product, a sheet-shaped resin composition having a thickness of 0.5 mm was obtained in accordance with “(6) Production of resin composition” in Example 1. In the “(6) Production of resin composition”, 2.6 parts by mass of the dried product was used with respect to 28 parts by mass of HDPE.

[Comparative Example 3]
A beaker was charged with 22.72 g of the acetone-containing acid-type fine cellulose fiber obtained in Example 1 (solid content adjusted from 5.0% by mass to 4.4% by mass), 133 g of isopropyl alcohol, ion-exchanged water 67 g was added to obtain an acetone-containing acid-type fine cellulose fiber dispersion having a solid concentration of 0.5% by mass, and the mixture was stirred with a magnetic stirrer at room temperature for 1 hour. Subsequently, 1.86 g of octadecylamine was added, and after confirming dissolution, the reaction was performed at room temperature for 12 hours. After completion of the reaction, the mixture was filtered and then washed with ethanol to remove unreacted octadecylamine. Finally, acetone was added and filtered to obtain a fine cellulose fiber composite in which octadecyl groups were bonded to the fine cellulose fibers through ionic bonds. Using this fine cellulose fiber composite, a sheet-like resin composition having a thickness of 0.5 mm was obtained according to the procedures (3) to (6) of Example 1. In the “(6) Production of resin composition”, 0.8 part by mass of the resin modifying additive was used with respect to 28 parts by mass of HDPE.

[Comparative Example 4]
Without using a fine cellulose fiber composite, polyvinyl chloride resin (Viniblanc HD-057, manufactured by Nissin Chemical Industry Co., Ltd., solid content concentration 13% by mass) and polyethylene resin emulsion (trade names: Arrow Base SB1010, Unitika Ltd.) ), Solid content concentration of 25% by mass) was mixed in the same manner as in Example 5, then poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm, dried in a 23 ° C., 50% RH environment for one week, and film A dried product was obtained. This dried product was cooled and pressed in the same manner as in Example 5 to obtain a sheet-shaped resin composition having a thickness of 0.1 mm.

[Comparative Example 5]
Without using a fine cellulose fiber composite, polyamide resin (Separjon PA200, manufactured by Sumitomo Seika Co., Ltd., solid content concentration 40 mass%) and polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd., solid content) After mixing only in the same manner as in Example 6, the mixture was poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm and dried in an environment of 23 ° C. and 50% RH for one week. Obtained. This dried product was cooled and pressed in the same manner as in Example 6 to obtain a sheet-shaped resin composition having a thickness of 0.1 mm.

[Comparative Example 6]
Without using a fine cellulose fiber composite, polycarbonate resin (Separjon PA200, manufactured by Sumitomo Seika Co., Ltd., solid content concentration 40% by mass) and polyethylene resin emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd., solid content) After mixing only in the same manner as in Example 7, the mixture was poured into a polystyrene petri dish (φ80 mm) to a depth of about 0.8 cm and dried in a 23 ° C., 50% RH environment for one week. Obtained. This dried product was cooled and pressed in the same manner as in Example 7 to obtain a sheet-shaped resin composition having a thickness of 0.1 mm.

[Evaluation]
About the sample (resin composition) of an Example and a comparative example, the tensile elasticity modulus and Yi value were measured with the following method, respectively. The results are shown in Tables 1 and 2 below together with the composition of each resin composition.

<Method for measuring tensile modulus of resin composition>
As described below, the tensile modulus measurement method varies depending on the form (thickness) of the resin composition. However, regardless of the difference in measurement method, the higher the tensile modulus, the better the mechanical strength and the higher the evaluation.
Examples 1-4 and Comparative Examples 1-3 (sheet-shaped resin composition thickness 0.5 mm)
The tensile elastic modulus, tensile yield strength, and elongation at break of the composite molded article were measured using a tensile / compression tester (RTA-500, manufactured by Orientec Co., Ltd.). A sample punched out with a No. 1 dumbbell as defined in JIS K-6251 was set at a fulcrum distance of 80 mm and measured at a crosshead speed of 30 mm / min.
Examples 5 to 7 and Comparative Examples 4 to 6 (sheet-shaped resin composition thickness 0.1 mm)
The tensile elastic modulus, tensile yield strength, and elongation at break of the composite molded article were measured using a tensile / compression tester (RTA-500, manufactured by Orientec Co., Ltd.). A sample punched out with a No. 2 dumbbell defined in JIS K-6251 was set at a fulcrum distance of 60 mm and measured at a crosshead speed of 30 mm / min.

<Measurement method of Yi value>
Using a spectrocolorimeter (CM-2500d, manufactured by Konica Minolta Co., Ltd.), the yellowness (Yi value) of the sheet-like resin composition was measured. In accordance with ASTM E313-73, standard illuminant D65 was used as a light source, measurement diameter φ8 mm, observation visual field 10 ° C., UV 100%, SCI / SCE simultaneous measurement. The SCI value was defined as Yi value. The smaller the Yi value, the lower the degree of coloring and the higher the evaluation.

  Examples 1 to 4 are resin compositions each containing a fine cellulose fiber composite in which hydrocarbon groups are bonded via an amide bond and high-density polyethylene, and Comparative Example 1 does not contain fine cellulose fibers. The tensile elastic modulus is improved as compared with each of Comparative Examples 2 (corresponding to the base polymers of Examples 1 to 4) and the fine cellulose fibers having no hydrocarbon group. The effect of improving the tensile modulus is considered to be a result of uniform dispersion of fine cellulose fibers that have been hydrophobized by introduction of hydrocarbon groups in the resin. In particular, Example 4 is a resin composition containing fine cellulose fibers (fine cellulose fiber composites) into which octadecyl groups have been introduced by amide bonds, and a slight fine cellulose fiber (fine cellulose fibers) of 0.5% by mass. It was confirmed that the tensile modulus was improved by 1.15 times (= 1015/883) of Comparative Example 1 while the content of the composite) was high. The tensile modulus of elasticity of 1015 MPa in Example 4 is higher than that in Comparative Example 3 including fine cellulose fibers in which octadecyl groups are similarly introduced by ionic bonding. From this, it is introduced into the fine cellulose fibers. It can be seen that an amide bond is effective as the bonding mode of the hydrocarbon group. In Comparative Examples 2 and 3, although the tensile modulus was improved as compared with Comparative Example 1 corresponding to these base polymers, the Yi value, which is the degree of coloring, was also significantly increased at the same time. On the other hand, the Yi values of Examples 1 to 4 remained low. The reason why the Yi values of Examples 1 to 4 are relatively low is considered to be due to the high thermal stability of the fine cellulose fiber composite having an amide bond.

In each of Examples 5 to 7, fine cellulose fibers into which a propyl group was introduced by an amide bond (fine cellulose fiber composite), and any one of a polyvinyl chloride resin, a polyamide resin, and a polycarbonate resin were used. It is a resin composition containing. Compared to Comparative Examples 4 to 6 (corresponding to the base polymers of Examples 5 to 7) not containing fine cellulose fibers, the tensile modulus was improved. Although the Yi value is higher than those of Comparative Examples 4 to 6, since the Yi value is smaller than those of Comparative Examples 2 and 3, use of fine cellulose fibers (fine cellulose fiber composites) having hydrocarbon groups introduced by amide bonds. It is considered that the increase in the Yi value was suppressed. If the Yi value is 25 or less, it is at a level where there is no practical problem.

Claims (7)

  One selected from the group consisting of a fine cellulose fiber composite in which a hydrocarbon group is bonded to a fine cellulose fiber via an amide bond, and a polyolefin resin, a polyvinyl chloride resin, a polyamide resin, and a polycarbonate resin. A resin composition containing the above resin.   The resin composition according to claim 1, wherein the hydrocarbon group is a hydrocarbon group having 1 carbon atom, or a saturated or unsaturated, linear or branched hydrocarbon group having 2 to 30 carbon atoms.   The resin composition according to claim 1 or 2, wherein an average bond amount of the hydrocarbon group is 0.1 mmol / g or more and 3 mmol / g or less.   The resin composition according to any one of claims 1 to 3, wherein a content of a carboxy group in the fine cellulose fiber composite is 0 mmol / g or more and 2.9 mmol / g or less.   The resin composition according to any one of claims 1 to 4, wherein the polyolefin resin is at least one selected from the group consisting of polyethylene and polypropylene. It is a manufacturing method of the resin composition as described in any one of Claims 1-5 , Comprising: The said fine cellulose fiber composite and the said resin are mixed, a uniform mixture is obtained, and this uniform mixture is made into arbitrary shapes. The manufacturing method of the resin composition which has the process to shape | mold. The method for producing a resin composition according to claim 6 , wherein the fine cellulose fiber composite is produced through the following steps 1 and 2.
Step 1: A step of oxidizing a natural cellulose fiber in the presence of an N-oxyl compound to obtain a carboxy group-containing cellulose fiber.
Step 2: A step of reacting a carboxy group-containing cellulose fiber obtained through Step 1 with a primary or secondary amine having a hydrocarbon group to carry out an amidation reaction of the carboxy group of the cellulose fiber.