JP2013014741A - Additive for modifying resin and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for modifying a resin suitably usable for producing a cellulose nanofiber composite molding where the cellulose nanofiber is highly dispersed in a resin.SOLUTION: This additive for modifying a resin includes a cellulose nanofiber obtained by making an N-oxyl compound to act on a natural cellulose fiber and/or the cellulose nanofiber derivative, and a resin particle. It is preferable that the cellulose nanofiber and/or the cellulose nanofiber derivative is present on the surface of the resin particle. It is preferable that a thermoplastic resin is used as the resin. The additive for modifying a resin is preferably produced by: preparing an emulsion containing cellulose nanofiber obtained by making an N-oxyl compound act on a natural cellulose fiber and/or a derivative of the cellulose nanofiber, a resin particle and a liquid medium; and removing the liquid medium from the emulsion by drying.

Description

  The present invention relates to an additive for resin modification. This additive for resin modification is suitably used for producing a cellulose nanofiber composite molded body.

  A technique is known in which fine cellulose fibers are combined with a resin to reinforce the resin. For example, Patent Document 1 proposes an MFC / resin composite material composed of a resin and microfibrillated cellulose (hereinafter also referred to as “MFC”). In this composite material, MFC that has been defibrated without agglomeration is uniformly dispersed so as to have voids, and resin particles are contained in the voids.

  In Patent Document 2, a reactant fiber obtained by allowing an N-oxyl compound and a cooxidant to act on natural cellulose is treated with an organic onium compound to produce a finely modified cellulose fiber. It has been proposed that an epoxy resin composite is obtained by adding to the epoxy resin and curing.

  Patent Document 3 proposes a film-forming agent comprising cellulose fibers composed of cellulose having a carboxyl group content of 0.1 to 2 mmol / g and a resin emulsion.

JP 2009-107155 A JP 2010-059304 A JP 2009-197122 A

  In the MFC / resin composite material described in Patent Document 1, the MFC does not have an electrostatic repulsive force such as a carboxyl group, and therefore normal drying is performed when water is removed during the production. I can't. This is because, when normal drying is performed, aggregation of MFCs occurs. Therefore, it is difficult to uniformly disperse MFC in the resin. As a result, in order to strengthen the resin by MFC, it is necessary to contain a large amount of MFC.

  In the epoxy resin composite described in Patent Document 2, due to the low compatibility between the epoxy resin and the fine cellulose fiber, it is necessary to make the cellulose fiber oleophilic using an organic onium compound at the time of compounding. is there. When the oleophilicity is not sufficient, the dispersion of the cellulose fibers in the epoxy resin is not uniform, and the epoxy resin cannot be sufficiently reinforced.

  According to the film forming agent described in Patent Document 3, a high-strength film can be formed. However, in the same document, the effects as a resin-modifying additive and a composite molded article are not mentioned.

  Accordingly, an object of the present invention is to provide an additive for resin modification that can eliminate the above-mentioned drawbacks of the prior art.

  The present invention provides a resin-modifying additive comprising cellulose nanofibers obtained by allowing an N-oxyl compound to act on natural cellulose fibers and / or derivatives of the cellulose nanofibers and resin particles. .

  Further, the present invention provides a cellulose nanofiber obtained by allowing an N-oxyl compound to act on natural cellulose fiber and / or a derivative of the cellulose nanofiber and a resin particle as a preferred method for producing the additive for resin modification. The present invention provides a method for producing an additive for resin modification, which comprises a step of preparing an emulsion containing an aqueous solution and a liquid medium, and then removing the liquid medium from the emulsion by drying.

  Furthermore, the present invention provides a method for producing a cellulose nanofiber composite molded body having a step of melt-kneading the above-mentioned resin-modifying additive and a thermoplastic resin and melt-molding the mixture.

  ADVANTAGE OF THE INVENTION According to this invention, the additive for resin modification used suitably for manufacture of the cellulose nanofiber composite molded object which the cellulose nanofiber disperse | distributed highly in resin is provided.

  Hereinafter, the present invention will be described based on preferred embodiments thereof. The additive for resin modification of the present invention is a cellulose nanofiber obtained by allowing an N-oxyl compound to act on a natural cellulose fiber and / or a derivative of the cellulose nanofiber (hereinafter these are simply referred to as “cellulose nanofiber”). It is also called “fiber”.) And resin particles. The resin-modifying additive of the present invention is typically in a state where cellulose nanofibers are present on the surface of the resin particles. This state is one aspect of the composite in the present invention. The resin-modifying additive of the present invention takes the form of particles in appearance. In some cases, it may be in the form of a lump or plate like a pellet in which cellulose nanofibers and resin particles are combined. Although it is difficult to directly observe the state of the cellulose nanofibers on the surface of the resin particles, the present inventors consider that the cellulose nanofibers are uniformly dispersed on the surface of the resin particles. The resin-modifying additive in such a composite state is manufactured as a master batch, the master batch is melt-kneaded with other molding resins, melt-molded, and a resin molded body is manufactured. The obtained resin molded body is a composite molded body of cellulose nanofiber and resin (hereinafter referred to as “cellulose nanofiber composite molded body” or simply “composite molded body”). In the composite molded body, cellulose nanofibers are uniformly dispersed in the composite molded body. As a result, the composite molded body is reinforced by cellulose nanofibers and has improved strength. Reinforcement with cellulose nanofibers is achieved by the use of a small amount of cellulose nanofibers due to the uniform dispersion of cellulose nanofibers in the composite molded body.

  The ratio between the cellulose nanofibers and the resin particles in the resin modifying additive is not particularly limited as long as the cellulose nanofibers can be uniformly dispersed on the surface of the resin particles. As a result of the study by the present inventors, it has been found that the ratio between cellulose nanofibers and resin particles can be selected from a wide range. Specifically, the ratio of cellulose nanofibers in the resin modifying additive is preferably 0.1 to 99% by mass, more preferably 1 to 50% by mass, and still more preferably 2 to 10% by mass. On the other hand, the ratio of the resin in the resin modifying additive is preferably 1 to 99.9% by mass, more preferably 50 to 99% by mass, and still more preferably 90 to 98% by mass. The ratio of cellulose nanofibers and the ratio of resin particles in the resin-modifying additive can be measured by, for example, thermogravimetric analysis or X-ray diffraction analysis. Specifically, when the resin particles are polyethylene, the thermal decomposition temperature of cellulose nanofibers is about 200 to 300 ° C., whereas the thermal decomposition temperature of polyethylene in a nitrogen atmosphere is about 200 to 300 ° C. The ratio can be calculated by measuring the decomposition weight of cellulose nanofibers.

  As the resin used for the resin modifying additive, either a thermoplastic resin or a thermosetting resin may be used. From the viewpoint of a high degree of freedom in molding, it is preferable to use a thermoplastic resin. As the thermoplastic resin, conventionally known melt-moldable thermoplastic resins can be used without any particular limitation. For example, polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polylactic acid, polyvinyl acetate, polyurethane, polystyrene, natural rubber, synthetic rubber, etc. Can do. These resins can be used alone or in combination of two or more. When two or more kinds of resins are used in combination, a mixture of resin particles of different resins or different resins can be used as the resin particles of the melt blend or copolymer. In particular, polyethylene, polypropylene, polylactic acid, polyvinyl acetate, and ethylene vinyl acetate co-polymerized from the viewpoint of dispersibility of cellulose nanofibers and improvement in strength of composite molded products when cellulose nanofiber composite molded products are formed by the method described later. It is preferable to use coalescence, polyacrylic acid and polyurethane.

  The resin described above is used in the form of particles. The average particle diameter of these particles is preferably 0.01 to 500 μm, particularly preferably 0.1 to 10 μm. This is because by adopting an average particle diameter in this range, the resin particles can be successfully made into an emulsion in the method for producing an additive for resin modification described later. The average particle diameter of the resin particles is measured by the following method. The particle size distribution is measured using a laser diffraction particle size distribution analyzer (SALD-300V, analysis software WingSALD-300V, manufactured by Shimadzu Corporation). The resin emulsified in advance is adjusted to an appropriate concentration with ion-exchanged water, and then the median diameter is measured from the particle size distribution to obtain the average particle diameter. The resin particles not dispersed in water are mixed with the cellulose nanofiber aqueous dispersion to be emulsified, and then the median diameter is measured in the same manner as the average particle diameter. The refractive indexes are all 1.5. In the resin modifying additive of the present invention, since the cellulose nanofibers present on the surface of the resin particles are thinly coated with the resin particles, the particle size of the resin modifying additive is determined from the raw material. Is substantially the same as the particle size of the resin particles.

  There are no particular limitations on the shape of the resin modifying additive and the resin particles used as the raw material, and various shapes can be used. From the viewpoint of successfully making the resin particles into an emulsion in the method for producing an additive for resin modification described below, it is preferable to use substantially spherical particles.

  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. In the case of using powdery resin particles, a surfactant, a dispersant, or the like may be used in order to successfully make the resin particles into an emulsion in the method for producing an additive for resin modification described later.

  The cellulose nanofibers present on the surface of the resin particles are fine ones having an average fiber diameter of preferably 200 nm or less, more preferably 1 to 200 nm, more preferably 1 to 100 nm, and still more preferably 1 to 50 nm. It is. By using cellulose nanofibers having an average fiber diameter of 200 nm or less, the resin can be effectively reinforced. The average fiber diameter is measured by the following method.

<Measurement method of average fiber diameter>
An aqueous dispersion of cellulose nanofibers having a solid content concentration of 0.001% by mass is prepared. An observation sample is obtained by dripping this dispersion liquid onto mica (mica) and drying it. The fiber height of the cellulose nanofiber in the observation sample is measured using an atomic force microscope (NanoNaVi IIe, SPA400, manufactured by SII Nano Technology Co., Ltd., and the probe uses SI-DF40Al manufactured by the same company). In a microscopic image in which cellulose nanofibers can be confirmed, five or more cellulose nanofibers are extracted, and the average fiber diameter is calculated from the fiber heights.

  The cellulose nanofiber used in the present invention is obtained by refining a natural cellulose fiber described later to a structural unit called microfibril. The shape of the microfibril varies depending on the raw material, but many natural cellulose fibers have a rectangular cross-sectional structure in which dozens of cellulose molecular chains are collected and crystallized. For example, microfibrils in the cell walls of higher plants have a square cross-sectional structure in which 6 × 6 cellulose molecular chains are gathered. Therefore, the height of the cellulose nanofiber obtained by an atomic force microscope image was used as the fiber diameter for convenience.

  In addition to being fine, cellulose nanofibers are also characterized by being obtained by allowing an N-oxyl compound to act on natural cellulose fibers. By using the cellulose nanofiber obtained by such a method, the above-mentioned fine fiber diameter can be easily achieved. In particular, the carboxyl group content of cellulose constituting the cellulose nanofiber is preferably 0.1 to 3 mmol / g, more preferably 0.4 to 2 mmol / g, and still more preferably 0.6 to 1.8 mmol. / G, and even more preferably 0.6 to 1.6 mmol / g, the above-mentioned fine fiber diameter can be more easily achieved.

  In the process of biosynthesis of natural cellulose fibers, normally, nanofibers called microfibrils are first formed, and these are multi-bundled to build a higher-order solid structure. Cellulose nanofibers used in the present invention are In order to weaken the hydrogen bond between the surfaces, which is obtained by using this in principle and is the driving force of strong cohesion between microfibrils in a naturally derived cellulose solid raw material, an N-oxyl compound is used. By acting, it is obtained by oxidizing a part of the hydroxyl groups on the microfibril surface and converting them to carboxyl groups. Therefore, the one where there is much sum total of the quantity of the carboxyl group which exists in a cellulose (carboxyl group content) can exist stably as a finer fiber diameter. Further, in water, an electric repulsive force is generated, so that the tendency of the microfibrils to break apart without maintaining aggregation is increased, and the dispersion stability of the nanofibers is further increased. The carboxyl group content is measured by the following method.

<Measurement method of carboxyl group content>
Cellulose nanofibers with a dry mass of 0.5 g are placed in a 100 ml beaker and ion-exchanged water is added to make a total of 55 ml. A dispersion is prepared by adding 5 ml of 0.01 M sodium chloride aqueous solution to sufficiently disperse cellulose fibers. The dispersion is stirred until. 0.1 M hydrochloric acid is added to this dispersion to adjust the pH to 2.5-3. Using an automatic titrator (AUT-50, manufactured by Toa DKK Co., Ltd.), 0.05M aqueous sodium hydroxide solution is added dropwise to the dispersion under conditions of a waiting time of 60 seconds. 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 carboxyl group content of the cellulose nanofiber is calculated according to the following formula.
Carboxyl group content (mmol / g) = sodium hydroxide titration (ml) × sodium hydroxide aqueous solution concentration (0.05 M) / mass of cellulose fiber (0.5 g)

  In addition, a nanofiber derivative obtained by subjecting cellulose nanofibers having a carboxyl group content in the above range by the action of an N-oxyl compound to a modification treatment is also preferably used in the present invention. In this derivative, the carboxyl group content of cellulose may be outside the above range, but in the process until the derivative is formed, the cellulose has a carboxyl group content within the above range. Therefore, a fine fiber diameter can be easily achieved. In addition, either the cellulose nanofiber obtained by making an N-oxyl compound act on natural cellulose fiber and the derivative | guide_body of this cellulose nanofiber can also be used, and both can also be used together.

  The length of the cellulose nanofiber is not particularly limited. When the fiber length is represented by an average aspect ratio (fiber length / fiber diameter), it is preferably 10 to 1000, more preferably 10 to 500, and still more preferably 100 to 350. The average aspect ratio is measured by the following method.

<Measuring method of average aspect ratio>
It is calculated from the viscosity of a dispersion prepared by adding water to cellulose nanofibers (concentration of cellulose nanofibers of 0.005 to 0.04% by 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 nanofibers in the dispersion and the specific viscosity of the dispersion with respect to water, the aspect ratio of the cellulose nanofibers is calculated back using the following formula (1) to obtain the average aspect ratio. Equation (1) is 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 nanofiber is square), ρ is the concentration (kg / m ³ ) of the cellulose nanofiber, M is the molecular weight, and N _A is the Avogadro number. In the viscosity formula (8.138), rigid rod-like molecule = cellulose nanofiber. In 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 ).

  Cellulose nanofibers can be obtained, for example, by a production method including an oxidation reaction step of oxidizing natural cellulose fibers to obtain reactant fibers, and a refinement step of miniaturizing the reactant fibers. In the oxidation reaction step, 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, using an N-oxyl compound as an oxidation catalyst, natural cellulose fibers are oxidized in water to obtain reactant fibers. Examples of N-oxyl compounds include 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO), 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO, and the like. Can be used. A catalytic amount is sufficient for the addition of the N-oxyl compound, and is usually in the range of 0.1 to 10% by mass relative to the natural cellulose fiber (absolute dry basis) used as a raw material.

  In the oxidation treatment of natural cellulose fiber, an oxidizing agent (for example, hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogenic acid or a salt thereof, hydrogen peroxide, a perorganic acid, etc.) and a co-oxidant (For example, 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.

  In the oxidation treatment of natural cellulose fibers, it is desirable to maintain the pH of the reaction solution (slurry) in the range of 9 to 12 from the viewpoint of allowing the oxidation reaction to proceed 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.

  After the oxidation reaction step, a purification step is performed before the miniaturization step to remove impurities other than the reactant fibers and water contained in the slurry, such as unreacted oxidant and various by-products. Since the reaction product fibers are not normally dispersed evenly at the nanofiber unit at this stage, in the purification step, for example, a purification method in which water washing and filtration are repeated can be performed. The purification apparatus used in that case is not particularly limited. The purified reaction product fiber thus obtained is usually sent to the next step (miniaturization step) impregnated with an appropriate amount of water. However, if necessary, it may be dried into a fiber or powder form. Good.

  In the miniaturization step, the reaction product fibers that have undergone the purification step are dispersed in a solvent such as water and subjected to a miniaturization treatment. By passing through this refinement | miniaturization process, the cellulose nanofiber which has an average fiber diameter and an average aspect ratio in the said range, respectively is obtained.

  In the miniaturization treatment, the solvent as the dispersion medium is usually water, but in addition to water, an organic solvent soluble in water (alcohols, ethers, ketones, etc.) may be used 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, an ultrasonic stirrer, and a household. Juicer mixer for use. The solid content concentration of the reactant fiber in the refinement treatment is preferably 50% by mass or less.

  Cellulose nanofibers obtained after the micronization step are in the form of a dispersed liquid with a solid content adjusted as needed (a visually colorless transparent or opaque liquid), or a dried powdery form (however, the cellulose fiber) Is an agglomerated powder and does not mean cellulose particles). When making a dispersion liquid, water alone may be used as a dispersion medium, or a mixed solvent of water and other organic solvents (for example, alcohols such as ethanol), surfactants, acids, bases, etc. is used. May be.

  By the oxidation treatment and refinement treatment of the natural cellulose fiber as described above, the hydroxyl group at the C6 position of the cellulose constituent unit is selectively oxidized to a carboxyl group via an aldehyde group, and the carboxyl group content is preferably 0. It is possible to easily obtain a highly refined highly crystalline cellulose fiber composed of 1 to 3 mmol / g cellulose and having an average fiber diameter of preferably 200 nm or less. This highly crystalline cellulose fiber has a cellulose I-type crystal structure. This means that the fine cellulose fiber used in the present invention is a fiber obtained by surface-oxidizing a naturally-derived cellulose solid raw material having an I-type crystal structure. 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 fiber is obtained by weakening the hydrogen bond between them by introduction of the aldehyde group or carboxyl group by the oxidation treatment, and further through the refinement treatment. And by adjusting the conditions for the oxidation treatment, the polarity can be changed by increasing or decreasing the carboxyl group content within a predetermined range, and by the electrostatic repulsion or refinement treatment of the carboxyl group, The average fiber diameter, average fiber length, average aspect ratio, etc. can be controlled.

  A cellulose nanofiber derivative may be obtained by modifying the carboxyl group on the surface of the cellulose nanofiber thus obtained. Examples of the modification treatment for the carboxyl group of cellulose nanofiber include methyl group, ethyl group, propyl group, 2-propyl group, butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, Examples thereof include carboxylic acid esterification or carboxylic acid amidation with an alkyl group such as octyl group, nonyl group, decyl group, undecyl group, dodecyl group, myristyl group, palmityl group and stearyl group.

  Examples of the modification treatment for the carboxyl group of cellulose nanofiber include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, hexylamine, Amine chloride with primary to tertiary alkylamines having the same or different alkyl groups having 1 to 18 carbon atoms, such as octylamine, decylamine, dodecylamine, stearylamine, octadecylamine; tetraethylammonium, tetrabutylammonium, tetrapropyl Ammonia, lauryltrimethylammonium, stearyltrimethylammonium, distearyldimethylammonium, etc. Ammonium chloride with quaternary ammonium compounds having different or different alkyl groups; imidazolium chloride with imidazolium compounds such as 1,3 dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium; N, N ′ -Imidazolinium chloride with imidazolinium compounds such as dimethylimidazolinium, 1,2,3-trimethylimidazolinium; phosphonium with phosphonium compounds such as tetraethylphosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tetraphenylphosphonium And chloride.

  Furthermore, the cellulose nanofiber derivative may be obtained by modifying the hydroxyl group on the surface of the cellulose nanofiber. Examples of modification treatment for the hydroxyl group of cellulose nanofiber include acetyl group, acryloyl group, methacryloyl group, propionyl group, propioyl group, butyryl group, 2-butyryl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, nonanoyl group , Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, benzoyl group, naphthoyl group, nicotinoyl group, isonicotinoyl group, furoyl group, cinnamoyl group and other acyl groups, 2-methacryloyloxyethyl isocyania Isocyanate group such as noyl group, methyl group, ethyl group, propyl group, 2-propyl group, butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl , Nonyl group, decyl group, undecyl group, dodecyl group, myristyl group, palmityl group, an alkyl group such as a stearyl group, an oxirane group, an oxetane group, a thiirane group, and a thietane group treatment. Cellulose nanofiber derivatives obtained by such various modification treatments have improved dispersibility in resins used in composite molded products due to the change in hydrophilicity / hydrophobicity of unmodified cellulose nanofibers. And can be arbitrarily selected according to the resin used.

  The additive for resin modification of the present invention contains the above-mentioned cellulose nanofibers and resin particles, and further contains a dispersing agent such as a crosslinking agent, clay mineral, and surfactant, a colorant, an antistatic agent, and the like as necessary. May be included.

  Next, the suitable manufacturing method of the additive for resin modification | change of this invention is demonstrated. This production method includes the steps of (a) preparing an emulsion containing cellulose nanofibers, resin particles and a liquid medium, and (b) removing the liquid medium from the emulsion by drying. Hereinafter, each of the steps (a) and (b) will be described.

  In the step (a), water is usually used as the liquid medium used for mixing the cellulose nanofibers and the resin particles, but other mediums that can disperse the cellulose nanofibers, for example, water-insoluble Examples thereof include an organic medium, a water-soluble organic medium, a water-soluble organic medium, and 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), for example, cellulose nanofibers, resin particles, and a liquid medium can be mixed to prepare an emulsion. From the viewpoint of ease of preparation of the emulsion, it is advantageous to prepare the emulsion by mixing the resin particles in an emulsion state (that is, a resin emulsion dispersed in a liquid medium in advance) and cellulose nanofibers. 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 prepared by mixing powdery resin particles (that is, a dry resin powder that has not been previously dispersed in a liquid medium) and cellulose nanofibers. You can also At this time, even if the resin powder is a combination that is difficult to disperse in the liquid medium, the cellulose nanofibers can be used as a dispersant to form an emulsion, or the emulsion can be formed using a dispersant other than a surfactant or cellulose nanofiber. You can also.

  By mixing the resin emulsion and a dispersion of cellulose nanofibers, a target cellulose nanofiber / resin particle emulsion can be obtained. The concentration of cellulose nanofibers contained in this emulsion is preferably 0.1 to 40% by mass, particularly preferably 0.2 to 5% by mass. It is preferable that the density | concentration of the resin particle is 0.1-50 mass%, especially 0.1-10 mass%. In addition to cellulose nanofibers and resin particles, this emulsion may contain a crosslinking agent, clay mineral, a surfactant or other dispersant, a colorant, an antistatic agent, etc., if necessary. .

  In the step (b), the liquid medium is removed from the cellulose nanofiber / resin particle emulsion thus obtained to obtain the resin-modifying additive of the present invention. 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. Even if any drying method is used, the aggregation of cellulose nanofibers hardly occurs. The reason for this is due to electrostatic repulsion caused by carboxyl groups generated by allowing an N-oxyl compound to act on natural cellulose fibers. On the other hand, since the microfibrillated cellulose described in Patent Document 1 described in the background art section does not have an electrostatic repulsive force due to a carboxyl group or the like, natural drying or heat drying is performed. The cellulose is agglomerated. In order to prevent this, freeze-drying is adopted in this document. In the present invention, lyophilization is not essential (of course, lyophilization is not prevented).

  From the viewpoint of the drying efficiency of the resin-modifying additive and the combination of cellulose nanofibers and resin particles, it is preferable to carry out spray drying of the emulsion as a drying method. In spray drying, the emulsion may be ejected from a nozzle to form fine droplets, and then heated and dried in convection air. In this method, a commonly used spray dryer can be used.

  The thus obtained resin-modifying additive (which may be dried from the emulsion state or subsequently melt-molded) may be used as, for example, a chip-shaped masterbatch. A cellulose nanofiber composite molded body can be obtained by adding this master batch to a thermoplastic resin using an extruder, melt kneading, and melt molding. As this thermoplastic resin, for example, the same resins as various resins constituting the resin particles described above can be used. This 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 cellulose nanofibers in the intended cellulose nanofiber composite molded article can be easily increased. When different types of resins are used, it is preferable to employ a combination of compatible resins.

  The obtained cellulose nanofiber composite molded body has improved strength due to reinforcement by cellulose nanofibers. That is, it can be said that the cellulose nanofiber composite molded body is a cellulose nanofiber reinforced resin molded body. Even if the ratio of the cellulose nanofiber contained in the molded product is as small as 0.1 to 50% by mass, particularly 0.5 to 10% by mass, it is sufficient for improving the strength of the resin. This is because cellulose nanofibers are highly dispersed in the molded body. The cellulose nanofiber composite molded body is highly transparent. This is also because cellulose nanofibers are highly dispersed in the molded body.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
(1) Manufacture of cellulose nanofibers Conifer bleached kraft pulp (manufacturer: Fletcher Challenge Canada, trade name “Machenzi”, 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 stat, 0.5M sodium hydroxide was added dropwise to maintain the pH at 10.5, and an oxidation reaction was performed. After 120 minutes of oxidation, dropping was stopped to obtain oxidized pulp. The oxidized pulp was thoroughly washed with ion-exchanged water and then dehydrated. Thereafter, 3.9 g of oxidized pulp and 296.1 g of ion-exchanged water were stirred for 10 minutes by a mixer (Vita-Mix-Blender ABSOLUTE, Osaka Chemical Co., Ltd.). By the operation, the fiber was refined to obtain a dispersion of cellulose nanofibers. The solid content concentration of the dispersion was 1.3% by mass. The average fiber diameter of the cellulose nanofibers was 3.3 nm, the average aspect ratio was 305, and the carboxyl group content was 1.2 mmol / g.

(2) Preparation of resin emulsion A polyethylene emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Ltd.) was used. The concentration of the resin particles was 25% by mass, and the average particle size of the resin particles was 0.22 μm. The shape of the resin particles was spherical.

(3) Preparation of cellulose nanofiber / resin particle emulsion 600 g of the cellulose nanofiber dispersion obtained in (1) above and 31.2 g of the polyethylene water emulsion prepared in (2) above in a beaker. Pour and mix for 30 minutes using a magnetic stirrer. Thus, the intended emulsion was obtained.

(4) Production of resin modifying additive The emulsion obtained in (3) above was spray-dried to obtain a resin modifying additive. For the spray drying, a spray dryer (spray dryer ADL311S-A, manufactured by Yamato Scientific Co., Ltd.) was used. The spray drying conditions were a nozzle diameter of 1.6 mm, an inlet temperature of 150 ° C., an outlet temperature of about 72 ° C., and a spray pressure of 0.15 MPa. The cellulose nanofiber content in the obtained resin-modifying additive is 50% by mass.

(5) Manufacture of cellulose nanofiber composite molded body The resin-modifying additive and low-density polyethylene resin (LDPE, trade name: Novatec LD LC561, manufactured by Nippon Polyethylene Co., Ltd.) obtained in (4) above, The mixture was melt kneaded using a kneader (Laboplast Mill, manufactured by Toyo Seiki Co., Ltd.). 2 parts by mass of the obtained resin modifying additive was added to 100 parts by mass of LDPE and kneaded at 150 ° C. 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. Thus, a sheet-like cellulose nanofiber composite molded body having a thickness of 0.5 mm was obtained. The cellulose nanofiber content in the composite molded body was 1.0% by mass.

[Example 2]
A cellulose nanofiber / resin particle emulsion was prepared in the same manner as in Example 1 using 300 g of the cellulose nanofiber dispersion used in Example 1 and 15.6 g of polyethylene emulsion. This emulsion was poured into a petri dish made of polystyrene (φ80 mm) to a depth of about 0.8 cm and dried in a 23 ° C., 50% RH environment for 1 week. In this way, an additive for resin modification was obtained. This resin-modifying additive was in the form of a cast film. The cellulose nanofiber content calculated from the charged amount at the time of preparing the emulsion was 50% by mass. The resin modifying additive (2.0 parts by mass) was added to 100 parts by mass of LDPE, and a cellulose nanofiber composite molded body was obtained in the same manner as in Example 1. The cellulose nanofiber content in the composite molded body was 1.0% by mass.

Example 3
A resin modifying additive prepared in Example 2 with respect to 100 parts by mass of HDPE using high density polyethylene resin (HDPE, trade name: Novatec HD HB338RE, manufactured by Nippon Polyethylene Co., Ltd.) instead of LDPE 3.1 mass In addition, a cellulose nanofiber composite molded body was obtained in the same manner as in Example 2. The cellulose nanofiber content in the composite molded body was 1.5% by mass.

Example 4
66.8 g of polypropylene emulsion (trade name: Hitech P-5300, manufactured by Toho Chemical Co., Ltd., solid content concentration 35% by mass, average particle size 0.18 μm, shape: sphere) and cellulose nano used in Example 1 An emulsion was obtained by mixing 600 g of a fiber dispersion. This emulsion was dried in the same manner as in Example 2 to obtain an additive for resin modification. The cellulose nanofiber content of this resin modifying additive was 25% by mass.

  A polypropylene resin (PP, trade name: Novatec PP BC03L, manufactured by Nippon Polypropylene Co., Ltd.) was used instead of LDPE, and 9.9 parts by mass of the resin-modifying additive was added to 100 parts by mass of PP. Example 2 In the same manner as above, a cellulose nanofiber composite molded body was obtained. The cellulose nanofiber content in the composite molded body was 2.2% by mass.

[Comparative Example 1]
Without using the cellulose nanofiber dispersion, only 40 g of polyethylene emulsion was dried in the same manner as in Example 1 to obtain a dried product. A molded body was obtained in the same manner as in Example 1 except that 1 part by mass of the dried product was added to 100 parts by mass of LDPE.

[Comparative Example 2]
Only the water emulsion 40g of polyethylene was dried like Example 2 without using the dispersion liquid of cellulose nanofiber. A molded body was obtained in the same manner as in Example 3 except that 1.5 parts by mass of this dried product was added to 100 parts by mass of HDPE.

[Comparative Example 3]
Instead of the dispersion of cellulose nanofibers, an MFC (trade name: Selish FD-200L, manufactured by Daicel Chemical Industries, Ltd.) dispersion prepared with ion exchange water to a solid content concentration of 1.3% by mass was used. 300 g of this MFC dispersion and 15.6 g of the polyethylene emulsion used in Example 1 were mixed to obtain an emulsion. This emulsion was dried in the same manner as in Example 2 to obtain a dried product. The MFC content in the dried product was 50% by mass. A molded body was obtained in the same manner as in Example 3 except that 3.1 parts by mass of the dried product was added to 100 parts by mass of HDPE.

[Comparative Example 4]
Without using the cellulose nanofiber dispersion, only 40 g of the polypropylene emulsion was dried in the same manner as in Example 2 to obtain a dried product. A molded body was obtained in the same manner as in Example 4 except that 7.1 parts by mass of this dried product was added to 100 parts by mass of PP.

[Comparative Example 5]
This comparative example is an example in which cellulose nanofibers are not used in the form of a resin-modifying additive, but are used in the form of a dried product of cellulose nanofibers alone. The cellulose nanofiber dispersion used in Example 1 was dried by a casting method to obtain a dried cellulose nanofiber. Using 1.5 parts by mass of the dried product and 100 parts by mass of HDPE used in Example 3, the mixture was kneaded in the same manner as in Example 1. The obtained kneaded material was pressed with a press in the same manner as in Example 3 to obtain a sheet-like cellulose nanofiber composite molded body having a thickness of 0.5 mm.

[Evaluation]
About the obtained composite molded object, the tensile elasticity modulus, the tensile yield strength, and the breaking elongation were measured with the following method. The results are shown in Table 1 below.

<Measuring method of tensile modulus, tensile yield strength and elongation at break of composite molded body>
Using a tensile and compression tester (RTA-500 manufactured by Orientec Co., Ltd.), the tensile elastic modulus, tensile yield strength, and breaking elongation of the composite molded article were measured in accordance with JIS K7113. A sample punched with No. 1 dumbbell was set at a fulcrum distance of 80 mm and measured at a crosshead speed of 30 mm / min. In addition, regarding the elongation at break, the measurement was terminated at that point when no breaking point appeared even when the elongation was 63 mm or more (breaking elongation: 79%).

  As is clear from the results shown in Table 1, the cellulose nanofiber composite molded body obtained in each example has a cellulose nanofiber content of 3% by mass or less and a tensile elastic modulus in each comparative example. Compared with 1.1 times or more, it had high mechanical strength. Example 1 is an additive for resin modification produced by a spray drying method, and Example 2 is a resin modification additive produced by a cast method. The composite molded body obtained from these is more elastic than the molded body obtained from Comparative Example 1. In addition, the tensile yield strength was high and the elongation was maintained. The composite molded body obtained from Example 3 had higher mechanical strength than the molded body of Comparative Example 2 that did not contain cellulose nanofibers, and was obtained from Comparative Example 3 using MFC instead of cellulose nanofibers. Compared to the molded body, it has high mechanical strength. The composite molded body produced by the method of Comparative Example 5 in which the cellulose nanofibers were not used in the form of a resin-modifying additive and was used as it was in the dry state of cellulose nanofibers alone was the same amount as in Example 3. While containing the cellulose nanofibers, the elastic modulus was lower than that of Example 3. From this, it can be said that the additive for resin modification of the present invention is suitable for the production of a reinforced resin molded article.

Example 5
Softwood 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 stat, 0.5M sodium hydroxide was added dropwise to maintain the pH at 10.5, and an oxidation reaction was performed. After 120 minutes of oxidation, dropping was stopped to obtain oxidized pulp. The oxidized pulp was thoroughly washed with ion-exchanged water and then dehydrated. Thereafter, 7.2 g of 1N hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 3 g of oxidized pulp and stirred gently for 1 hour, and then the oxidized pulp was sufficiently washed again with ion-exchanged water and dehydrated to remove carboxyl groups. Protonated oxidized pulp was obtained. Thereafter, 3 g of the protonated oxidized pulp, 297 g of ion-exchanged water, and 0.21 g of propylamine (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed, and a high-pressure homogenizer (desktop atomization tester NM2-2000AR, Yoshida Kikai Kogyo Co., Ltd.) The product was processed 5 times under the condition of a discharge pressure of 100 MPa. By the operation, the fiber was refined to obtain a dispersion of cellulose nanofiber derivative (propylamine salt type). The solid content concentration of the dispersion was 1.0% by mass. This cellulose nanofiber derivative had an average fiber diameter of 3.5 nm, an average aspect ratio of 220, and a carboxyl group content of 1.2 mmol / g.

  100 g of the cellulose nanofiber derivative dispersion and 36 g of a polyethylene emulsion (trade name: Arrow Base SB1010, manufactured by Unitika Co., Ltd.) are poured into a beaker and mixed for 30 minutes using a magnetic stirrer. An emulsion of resin particles was prepared. This emulsion was poured into a petri dish made of polystyrene (φ80 mm) to a depth of about 0.8 cm and dried in a 23 ° C., 50% RH environment for 1 week. In this way, an additive for resin modification was obtained. The cellulose nanofiber content of this resin-modifying additive was 10% by mass.

  A kneading machine (HDPE, trade name: Novatec HD HB338RE, manufactured by Nippon Polyethylene Co., Ltd.) and an adhesive resin (Adtex DH4200, manufactured by Nippon Polyethylene Co., Ltd.) Using a Laboplast mill, manufactured by Toyo Seiki Co., Ltd. 5 parts by mass of the resin modifying additive was added to 95 parts by mass of HDPE and 5 parts by mass of the adhesive resin, and kneaded at 150 ° C. for 10 minutes at a rotation speed of 70 rpm. The obtained kneaded product was hot-pressed at 150 ° 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.), further 23 ° C., 0. Cooling press was performed at 5 MPa for 1 minute. Thus, a sheet-like cellulose nanofiber composite molded body having a thickness of 0.5 mm was obtained. The cellulose nanofiber content in the composite molded body was 0.5% by mass.

Example 6
A dispersion of cellulose nanofiber derivative (hexylamine salt type) was obtained in the same manner as in Example 5 using 0.36 g of hexylamine (manufactured by Wako Pure Chemical Industries) instead of propylamine (manufactured by Wako Pure Chemical Industries). The solid content concentration of the dispersion was 1.0% by mass. This cellulose nanofiber derivative had an average fiber diameter of 3.5 nm, an average aspect ratio of 220, and a carboxyl group content of 1.2 mmol / g.

  A resin modifying additive was obtained in the same manner as in Example 5 except that the cellulose nanofiber derivative (hexylamine salt type) was used instead of the cellulose nanofiber derivative (propylamine salt type). The cellulose nanofiber content of this resin-modifying additive was 10% by mass. Using the resin-modifying additive, a cellulose nanofiber composite molded body was obtained in the same manner as in Example 5. The cellulose nanofiber content in the composite molded body was 0.5% by mass.

[Comparative Example 6]
Without using the cellulose nanofiber dispersion, only 40 g of polyethylene emulsion was dried in the same manner as in Example 5 to obtain a dried product. A molded body was obtained in the same manner as in Example 5 except that 4.7 parts by mass of the dried product was added to 95 parts by mass of HDPE and 5 parts by mass of the adhesive resin.

[Evaluation]
About the obtained composite molded object, the tensile elasticity modulus, the tensile yield strength, and the breaking elongation were measured similarly to Example 1. The results are shown in Table 2 below.

  As is clear from the results shown in Table 2, the composite molded body containing the cellulose nanofiber derivatives obtained in Examples 5 and 6 has a cellulose nanofiber content of 0.5% by mass, but has a tensile modulus of elasticity. Compared to Comparative Example 6, it was close to 1.1 times and had high mechanical strength. Moreover, since Examples 5 and 6 had little cellulose nanofiber content, they maintained high extensibility. From this, it can be said that the resin-modifying additive containing the cellulose nanofiber derivative of the present invention is suitable for the production of a reinforced resin molded article.

Example 7
Softwood 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 stat, 0.5M sodium hydroxide was added dropwise to maintain the pH at 10.5, and an oxidation reaction was performed. After 120 minutes of oxidation, dropping was stopped to obtain oxidized pulp. The oxidized pulp was thoroughly washed with ion-exchanged water and then dehydrated. Thereafter, 100 g of the oxidized pulp and 9900 g of ion-exchanged water were treated twice using a high-pressure homogenizer (Starburst Lab HJP-25005, manufactured by Sugino Machine Co., Ltd.) at a discharge pressure of 245 MPa. By the operation, the fiber was refined to obtain a dispersion of cellulose nanofibers. The solid content concentration of the dispersion was 1.0% by mass. This cellulose nanofiber derivative had an average fiber diameter of 3.4 nm, an average aspect ratio of 200, and a carboxyl group content of 1.2 mmol / g.

  700 g of the cellulose nanofiber dispersion and 93 g of low-density polyethylene powder (LDPE, trade name: Petrocene 202, manufactured by Tosoh Corporation) as resin particles were added to a high-pressure homogenizer (desk atomization tester NM2-2000AR, Yoshida Machine Industries, Ltd.) Was used under the condition of a discharge pressure of 100 MPa to obtain an emulsion. This emulsion 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 1 week. In this way, an additive for resin modification was obtained. The cellulose nanofiber content of this resin-modifying additive was 7% by mass.

  A kneading machine (HDPE, trade name: Novatec HD HB338RE, manufactured by Nippon Polyethylene Co., Ltd.) and an adhesive resin (Adtex DH4200, manufactured by Nippon Polyethylene Co., Ltd.) Using a Laboplast mill, manufactured by Toyo Seiki Co., Ltd. 80 parts by mass of the resin modifying additive was added to 100 parts by mass of HDPE and 5 parts by mass of the adhesive resin, and kneaded at 150 ° C. for 10 minutes at a rotation speed of 70 rpm. The obtained kneaded product was hot-pressed at 150 ° 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.), further 23 ° C., 0. Cooling press was performed at 5 MPa for 1 minute. Thus, a sheet-like cellulose nanofiber composite molded body having a thickness of 0.5 mm was obtained. The cellulose nanofiber content in the composite molded body was 3.0% by mass.

Example 8
A resin modifying additive was obtained in the same manner as in Example 7, except that 80 g of low density polyethylene powder and 2000 g of cellulose nanofiber dispersion were used. The cellulose nanofiber content of this resin modifying additive was 20% by mass. A cellulose nanofiber composite molded body was obtained in the same manner as in Example 7 except that 19 parts by mass of the resin-modifying additive was added. The cellulose nanofiber content in the composite molded body was 3.0% by mass.

Example 9
An additive for resin modification was obtained in the same manner as in Example 7 except that ethylene vinyl acetate copolymer powder (EVA, trade name: Ultrasen NM38-PW, manufactured by Tosoh Corporation) was used as the resin particles. The cellulose nanofiber content of this resin-modifying additive was 7% by mass. A cellulose nanofiber composite molded body was obtained in the same manner as in Example 7 using the resin-modifying additive. The cellulose nanofiber content in the composite molded body was 3.0% by mass.

Example 10
An additive for resin modification was obtained in the same manner as in Example 7 except that polypropylene powder (PP, trade name: PPW-5 Powder, manufactured by Seishin Enterprise Co., Ltd.) was used as the resin particles. The cellulose nanofiber content of this resin-modifying additive was 7% by mass. A cellulose nanofiber composite molded body was obtained in the same manner as in Example 7 using the resin-modifying additive. The cellulose nanofiber content in the composite molded body was 3.0% by mass.

Example 11
An additive for resin modification was obtained in the same manner as in Example 7 except that ultra high molecular weight polyethylene powder (UDPE, trade name: Mipperon XM-330, manufactured by Mitsui Chemicals, Inc.) was used as the resin particles. The cellulose nanofiber content of this resin-modifying additive was 7% by mass. A cellulose nanofiber composite molded body was obtained in the same manner as in Example 7 using the resin-modifying additive. The cellulose nanofiber content in the composite molded body was 3.0% by mass.

[Comparative Example 7]
A molded body was obtained in the same manner as Example 7 except that 74 parts by mass of low density polyethylene powder was added to 100 parts by mass of HDPE and 5 parts by mass of the adhesive resin without using cellulose nanofibers.

[Comparative Example 8]
A molded body was obtained in the same manner as in Example 7 except that 15 parts by mass of low-density polyethylene powder was added to 100 parts by mass of HDPE and 5 parts by mass of the adhesive resin without using cellulose nanofibers.

[Comparative Example 9]
A molded body was obtained in the same manner as in Example 7 except that 74 parts by mass of ethylene vinyl acetate copolymer powder was added to 100 parts by mass of HDPE and 5 parts by mass of adhesive resin without using cellulose nanofibers.

[Comparative Example 10]
A molded product was obtained in the same manner as in Example 7 except that 74 parts by mass of polypropylene powder was added to 100 parts by mass of HDPE and 5 parts by mass of the adhesive resin without using cellulose nanofibers.

[Comparative Example 11]
A molded body was obtained in the same manner as in Example 7 except that 74 parts by mass of ultrahigh molecular weight polyethylene powder was added to 100 parts by mass of HDPE and 5 parts by mass of the adhesive resin without using cellulose nanofibers.

[Evaluation]
Table 3 below shows the results of the tensile modulus, tensile yield strength, and breaking elongation of the obtained composite molded body.

  Examples 7 to 11 in which additives for resin modification were obtained from different types of resin particles and composite molded bodies were produced using the additives were respectively corresponding to Comparative Examples 7 to 11 in which no cellulose nanofibers were used. ing. In any of Examples 7-11, it turns out that the elasticity modulus is improving rather than the comparative example. The resin particles used in Examples 7 to 11 were all hydrophobic resin powders with low dispersibility in water. However, they can be successfully emulsified with cellulose nanofibers, so that they have high dispersibility. It is thought that it became. From this, it can be said that the additive for resin modification of the present invention is suitable for the production of a reinforced resin molded article.

Claims (8)

  An additive for resin modification comprising cellulose nanofibers obtained by allowing an N-oxyl compound to act on natural cellulose fibers and / or derivatives of the cellulose nanofibers, and resin particles.   The additive for resin modification according to claim 1, wherein cellulose nanofibers and / or derivatives of the cellulose nanofibers are present on the surface of the resin particles.   The additive for resin modification according to claim 1 or 2, wherein the resin constituting the resin particles is a thermoplastic resin.   The additive for resin modification according to claim 3, wherein the thermoplastic resin is polyethylene, polypropylene, polylactic acid, polyvinyl acetate, polyacrylic acid or polyurethane. It is a manufacturing method of the additive for resin modification of Claim 1,
An emulsion containing cellulose nanofibers obtained by allowing an N-oxyl compound to act on natural cellulose fibers and / or derivatives of the cellulose nanofibers, resin particles, and a liquid medium is prepared, and then the liquid medium is dried from the emulsion. The manufacturing method of the additive for resin modification which has the process of removing.   6. The emulsion is prepared by mixing the resin particles in an emulsion state and cellulose nanofibers obtained by allowing an N-oxyl compound to act on natural cellulose fibers and / or derivatives of the cellulose nanofibers. Manufacturing method.   The production method according to claim 5 or 6, wherein the liquid medium is removed by spray drying the emulsion.   The manufacturing method of the cellulose nanofiber composite molded body which has the process of melt-kneading the resin-modifying additive and thermoplastic resin of Claim 1, and melt-molding.