JP5613996B2 - Method for producing cellulose fiber-containing resin material - Google Patents

Description

  The present invention relates to a technique for uniformly dispersing hydrophilic cellulose fibers in a hydrophobic thermoplastic resin.

  BACKGROUND ART Fiber reinforced composite materials whose strength and rigidity are greatly improved by blending various fibrous reinforcing materials with resins are widely used in industrial fields such as electric / electronics, machinery, automobiles, and building materials. As the fibrous reinforcing material blended in the fiber-reinforced composite material, glass fibers having excellent strength and lightness are mainly used. However, in the glass fiber reinforced material, although high rigidity is achieved, the specific gravity is increased, so that there is a limit to weight reduction.

  On the other hand, fiber reinforcement made of organic materials such as polyester fiber, polyamide fiber, and aramid fiber has been studied as a fibrous reinforcement, but fiber reinforcement materials containing these reinforcements are lightweight and thermal recyclable. Although it can be secured, there is a problem that the mechanical reinforcement effect is not sufficient.

  On the other hand, in recent years, high-performance materials using plant-derived materials are attracting attention from the viewpoint of carbon neutral, and fiber composite materials in which cellulose fibers obtained by fibrillating and fibrillating these plant fibers have been proposed. .

  As a method of dispersing these fibers in the resin, a method of mixing the fibers and the resin and dispersing them using a biaxial kneader is generally used, but it is difficult to disperse the fibers in the resin at the nano level. Therefore, sufficient mechanical strength has not been secured.

  Patent Document 1 discloses a resin composite material containing microfibrillated cellulose (MFC) surface-treated as a reinforcing material in a resin material, and after mixing an emulsion of MFC and a matrix resin, the matrix resin Although there is a description of a method for producing a resin composite material that is added and kneaded, the matrix resin emulsion only describes an example in which an aqueous solvent is used, and does not describe how to use a hydrophobic resin. As general-purpose resins, there are many hydrophobic resins. For example, it is impossible to apply the production method described in Patent Document 1 to resins with a large production amount such as polyethylene terephthalate (PET) and polycarbonate (PC). It is.

  Patent Document 2 includes a step of removing the solvent after mixing the microfibrillated cellulose (MFC) dispersibility and resin solubility with the dispersion of the microfibrillated cellulose and dissolving the resin, Although a method for producing a microfibrillated cellulose-containing resin molded product is described, the MFC and the resin are mixed only in one stage, and the MFC and the resin are not uniformly dispersed, and are particularly exposed to high temperatures. In mixing by the kneading method, the tensile strength and bending strength are reduced.

  When mixing with a general-purpose resin such as polyethylene terephthalate (PET), polycarbonate (PC) or the like with a high production amount, a melt mixing method is used to dissolve the resin at a high temperature. For this reason, the production method of Patent Document 2 cannot be applied to a general-purpose resin.

JP 2008-184493 A JP 2008-24795 A

  Conventionally, when microfibrillated cellulose (MFC) is dispersed in a resin, a hydrophilic resin has been used, and mixing with a hydrophobic resin has been a difficult problem. However, most of the general-purpose resins that have a large production amount are hydrophobic resins. MFC is hydrophilic, and such a hydrophobic resin has poor compatibility, making it difficult to uniformly disperse MFC.

  In addition, since there are many thermoplastic resins in the hydrophobic resin, a melt mixing method is often used as a molding method, but this melt mixing method causes aggregation of MFC by exposure to high temperatures, Uniform dispersion cannot be achieved, and the target mechanical strength cannot be improved.

  The problem to be solved by the present invention is that the MFC is uniformly dispersed in a thermoplastic resin represented by PET, which is widely demanded in the industry, to improve the mechanical strength, and to impart heat resistance. Is to provide a method for producing a cellulose fiber-containing resin material (a composite material of cellulose fiber and thermoplastic resin) that can maintain transparency.

  The object of the present invention is achieved by the following configurations.

  1. A method for producing a resin material comprising a thermoplastic resin and a surface-treated cellulose fiber having an average fiber diameter of 2 nm or more and 200 nm or less, wherein the surface-treated cellulose fiber, an organic solvent, and a first thermoplastic resin A method for producing a cellulose fiber-containing resin material, comprising: a first mixing step of mixing, and a second mixing step of further mixing a second thermoplastic resin having a molecular weight larger than that of the first thermoplastic resin.

  2. The molecular weight of the first thermoplastic resin mixed in the first mixing step is 500 or more and 50,000 or less, and the molecular weight of the second thermoplastic resin mixed in the second mixing step is 50,000 or more and 1,000,000 or less. 2. The method for producing a cellulose fiber-containing resin material as described in 1 above.

  3. 3. The method for producing a cellulose fiber-containing resin material according to 1 or 2, wherein the concentration of the cellulose fiber at the end of the second mixing step is 1% by mass to 30% by mass with respect to the total amount of the resin.

  4). 4. The method for producing a cellulose fiber-containing resin material according to any one of 1 to 3, wherein the organic solvent contains a hydroxyl group.

  5. The method for producing a cellulose fiber-containing resin material according to any one of 1 to 4, wherein the organic solvent is removed after the first mixing step and the second mixing step is performed.

  According to an embodiment of the present invention, cellulose fibers can be uniformly dispersed in a transparent thermoplastic resin, and the mechanical strength such as tensile strength, bending strength, and low linear expansion of the polymer film or the polymer composite alone while maintaining transparency. The characteristics could be greatly improved. Surprisingly, the heat resistance of the resin could be remarkably improved.

Sectional drawing of an extensional flow kneading chamber is shown.

  Hereinafter, although this invention is demonstrated based on embodiment, it is not limited to these.

  The present invention is a method for producing a resin material containing a thermoplastic resin and a surface-treated cellulose fiber having an average fiber diameter of 2 nm to 200 nm, the surface-treated cellulose fiber, an organic solvent, and a first It has the 1st mixing process which mixes a thermoplastic resin, and the 2nd mixing process which further mixes the 2nd thermoplastic resin with larger molecular weight than a 1st thermoplastic resin, It is characterized by the above-mentioned.

  Hereinafter, the present invention will be described in more detail.

(Cellulose fiber)
The cellulose fiber of the present invention only needs to be defibrated to a state where the average fiber diameter is 2 nm or more and 200 nm or less, and the fiber surface may be further subjected to surface treatment by chemical modification or physical modification.

  Examples of the raw material cellulose fiber used in the present invention include plant-derived pulp, wood, cotton, hemp, bamboo, cotton, kenaf, hemp, jute, banana, coconut, seaweed, tea leaves, and other fibers separated from plant fibers, marine animals Examples include fibers separated from animal fibers produced by sea squirts, and bacterial cellulose produced from acetic acid bacteria. Among these, fibers separated from plant fibers can be preferably used, but fibers obtained from plant fibers such as pulp and cotton are more preferable.

  In the present invention, these fibers are defibrated using a homogenizer, a grinder or the like to obtain a microfibrillated cellulose fiber, but as long as the contained cellulose maintains the fiber state, There is no restriction | limiting about the defibrillation processing method. In addition, hard materials such as wood may need to be pulverized with a dry pulverizer as pre-crushing if they cannot be processed directly with a homogenizer.

  As a specific example, cellulose fibers such as pulp are introduced into a dispersion vessel containing water so as to be 0.1 to 3% by mass, and this is defibrated with a high-pressure homogenizer to obtain an average fiber diameter of 0.1. An aqueous dispersion of cellulose fibers defibrated to about 10 μm microfibrils is obtained. Furthermore, by repeatedly grinding with a grinder or the like, nano-order cellulose fibers having an average fiber diameter of about 2 to 200 nm can be obtained.

  Examples of the grinder used for the grinding treatment include a pure fine mill (manufactured by Kurita Machinery Co., Ltd.). As another method, there is a method using a high-pressure homogenizer in which cellulose fiber dispersion is jetted from a pair of nozzles at a high pressure of about 250 MPa, and the jet fibers collide with each other at a high speed to pulverize the cellulose fibers. Are known. Examples of the apparatus used include “Homogenizer” manufactured by Sanwa Machinery Co., Ltd., “Artemizer System” manufactured by Sugino Machine Co., Ltd., and the like.

  The average fiber diameter of the cellulose fibers obtained by fibrillation in this manner is preferably 2 nm or more and 200 nm or less, more preferably 2 nm or more and 100 nm or less, and further preferably 4 nm or more and 40 nm or less. The average fiber diameter shown here is an average value of the diameters of the fibers dispersed in the resin. In the present invention, the average fiber diameter and the measurement of the average fiber length to be described later are measured for the obtained fibers with a transmission electron microscope. , H-1700FA type (manufactured by Hitachi, Ltd.) was observed at a magnification of 10000 times, and 100 fibers were randomly selected from the obtained image, and each image was selected using image processing software (WINROOF). The fiber diameter and the fiber length are analyzed, and their simple number average value is obtained.

  In this invention, when the average fiber diameter of a cellulose fiber exceeds 200 nm, there exists a possibility that the intensity | strength of a fiber composite material may become inadequate. Furthermore, when mixed with a transparent resin, the transparency of the resin is adversely affected.

  Moreover, although it does not specifically limit about the length of a cellulose fiber, 50 nm or more is preferable by average fiber length, More preferably, it is 100 nm or more.

(Surface treatment method of cellulose)
In order to maintain good dispersibility of cellulose fibers having an average fiber diameter of 2 nm or more and 200 nm or less, surface modification is preferably performed. The surface modification of the cellulose fiber includes chemical modification or physical modification, but is preferably a chemical modification method, and the chemical modification will be described more specifically.

  In the present invention, the hydroxyl group of the cellulose fiber is chemically modified using a modifying agent such as an acid, an alcohol, a halogenating reagent, an acid anhydride, an isocyanate, a silane coupling agent, or a polymer. The chemical modification can be carried out according to a known method. For example, after cellulose fiber that has been defibrated is added to water or an appropriate solvent and dispersed, then a chemical modifier is added to the reaction to perform an appropriate reaction. What is necessary is just to make it react on conditions. In this case, in addition to the chemical modifier, a reaction catalyst can be added as necessary. For example, pyridine, N, N-dimethylaminopyridine, triethylamine, sodium methoxide, sodium ethoxide, sodium hydroxide, etc. A basic catalyst or an acidic catalyst such as acetic acid, sulfuric acid, or perchloric acid can be used, but a basic catalyst such as pyridine is preferably used in order to prevent a decrease in reaction rate and degree of polymerization.

  As reaction temperature, about 40-100 degreeC is preferable at the point which suppresses deterioration, such as yellowing of a cellulose fiber, and the fall of a polymerization degree, and ensuring reaction rate. The reaction time may be appropriately selected depending on the modifier used and the processing conditions.

  Examples of functional groups introduced into cellulose fibers by chemical modification include, for example, acetyl group, methacryloyl group, propanoyl group, butanoyl group, iso-butanoyl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, methyl group, ethyl group, Examples include propyl group, iso-propyl group, butyl group, iso-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group and the like.

  On the other hand, recently, there are reports that defibration treatment and surface modification are performed simultaneously. In this method, natural cellulose obtained by removing and purifying impurities such as lignin from plant resources is once dissolved in a solvent, and then regenerated cellulose is used as a raw material. In this method, an oxidation reaction such as hypochlorous acid is allowed to proceed in the presence of 2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter referred to as TEMPO). According to this, the cellulose chain forming the regenerated cellulose is at the molecular chain level, and only the primary hydroxyl group at the C6 position in the glucopyranose ring, which is a constituent monomer unit of the cellulose chain, is selectively oxidized and passes through the aldehyde. It is oxidized to a carboxyl group. The method of this report ("Cellulose" Vol. 5, 1998, pages 153 to 164, article entitled "Preparation of polyuronic acid from cellulose by TEMPO-catalyzed oxidation" by A. Isogai and Y. Kato) cellulose fiber It is also possible to use it for the cellulose fiber produced by this method for producing the nanofiber. Nanofibers of cellulose fibers prepared by this method can also be used as cellulose fibers having surface hydroxyl groups modified in the same manner as the above chemical modification method.

  Since the surface-treated cellulose fiber has a hydroxyl group modified on the surface, the concentration of the cellulose fiber with respect to the solvent can be 1% by mass or more and 30% by mass or less. Moreover, it is also possible to make it 5 mass% or more and 30 mass% or less preferably, and a yield can be raised.

  The cellulose fiber defibrating treatment is preferably performed at a cellulose fiber concentration of 0.1% by mass or more and 3% by mass or less with respect to water as a solvent. The cellulose fiber after the fiber treatment may be once dried by means of air drying, oven drying, vacuum drying, freeze drying or the like, and then dispersed in a solvent at a concentration necessary for the surface treatment. Moreover, when performing surface treatment, the density | concentration of the cellulose fiber immediately after defibration is 0.1 mass% or more and 3 mass% or less, and after the surface treatment, the density | concentration with respect to the solvent of a cellulose fiber is 1 mass% or more and 30 mass%. You may concentrate by concentration methods, such as an evaporator and a membrane separation method, so that it may become the following. If possible, the concentration of cellulose fibers immediately after defibration is such that a cellulose dispersion of 0.1% by mass or more and 3% by mass or less is concentrated by a concentration method such as an evaporator or a membrane separation method, followed by surface treatment. Also good. Before surface treatment, many hydroxyl groups are exposed on the cellulose surface and cause gelation. Therefore, a concentration method after surface treatment is preferable.

(Surface treatment using silane coupling agent)
In the present invention, a silane coupling agent may be used as a surface treatment method for cellulose. As a specific silane coupling agent,
Silazanes: vinylsilazane, hexamethyldisilazane, tetramethyldisilazanechlorosilanes: trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane alkoxysilanes: trimethylmethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, vinyl Trimethoxysilane silane coupling agents: vinyltriacetoxysilane, vinyltris (methoxyethoxy) silane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, etc. are applicable, trimethylmethoxysilane, dimethyldimethoxysilane, Methyltrimethoxysilane, hexamethyldisilazane, trimethylchlorosilane and the like are preferable.

  Moreover, when introduce | transducing a reactive group, the silane coupling agent which can introduce | transduce a reactive group is used preferably, for example.

  These silane coupling agents may be appropriately diluted with hexane, toluene, methanol, ethanol, acetone, methyl ethyl ketone (MEK), pyridine, water, or the like.

  These silane coupling agents may be used alone or in combination, and cellulose fibers treated with a silane coupling agent may be further treated with a silane coupling agent.

  The ratio of the silane coupling agent is not particularly limited, but the ratio of the silane coupling agent is preferably 10% by mass or more and 99% by mass or less, and 30% by mass or more and 98% by mass with respect to the cellulose fiber. The following is more preferable.

(Surface treatment using amphiphilic polymer)
Although there is physical modification as the surface modification of the cellulose fiber, a physical modification method using an amphiphilic polymer may be used.

  The amphiphilic polymer is a polymer having both a hydrophilic component and a lipophilic component in a polymer unit, and has a property of being dissolved and dispersed in both an organic solvent and water.

  The polymer may be a homopolymer composed of a single monomer having both a hydrophilic component and a lipophilic component in the side chain, or may be a copolymer polymer obtained by copolymerizing a hydrophilic component monomer and a lipophilic component monomer.

  As a single monomer having both a hydrophilic component and a lipophilic component, for example, (polyoxyalkylene) acrylate and methacrylate are commercially available hydroxypoly (oxyalkylene) materials such as “Pluronic” (Pluronic (Asahi Denka Kogyo Co., Ltd.)). Adeka Polyether (Asahi Denka Kogyo Co., Ltd.), Carbowax [Carbowax (Glico Products)], Triton [Toriton (Rohm and Haas)] and E. Those generally sold as G (Daiichi Kogyo Seiyaku Co., Ltd.) can be used.

  Alternatively, an amphiphilic polymer may be prepared by copolymerizing a hydrophilic component monomer and a lipophilic component monomer. In this case, an acrylic resin that is easy to polymerize and has a wide variety of monomers is preferred. The acrylic resin may be a homopolymer based only on the acrylic monomer, or may be copolymerized with other monomers based on the acrylic monomer. May be.

  Examples of the acrylic monomer include general acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylic chloride, methacrylic chloride, and acrylic acid anhydride.

  As a commercially available product having a special structure, as a polyalkylene glycol mono (meth) acrylate manufactured by NOF Corporation, Blemmer PE-90, Blemmer PE-200, Blemmer PE-350, Blemmer AE-90, Blemmer AE -200, Blemmer AE-400, Blemmer PP-1000, Blemmer PP-500, Blemmer PP-800, Blemmer AP-150, Blemmer AP-400, Blemmer AP-550, Blemmer AP-800, Blemmer 50 PEP-300, Blemmer 70 PEP -350B, Blemmer AEP series, Blemmer 55PET-400, Blemmer 30PET-800, Blemmer 55PET-800, Blemmer AET series, Blemmer 30PPT-800, Buremer Ma 50PPT-800, Blemmer 70PPT-800, Blemmer APT series, Brenmer 10PPB-500B, such as Brenmer 10APB-500B and the like. Similarly, Blemmer PME-100, Blemmer PME-200, Blemmer PME-400, Blemmer PME-1000, Blemmer PME-4000, Blemmer AME-400, Blemmer as alkyl-terminated polyalkylene glycol mono (meth) acrylates manufactured by NOF Corporation. 50POEP-800B, Blemmer 50AOEP-800B, Blemmer PLE-200, Blemmer ALE-200, Blemmer ALE-800, Blemmer PSE-400, Blemmer PSE-1300, Blemmer ASE series, Blemmer PKEP series, Blemmer AKEP series, Blemmer AE-300 , Blemmer ANE-1300, Blemmer PNEP series, Blemmer PNPE series, Blemmer 43ANE -500, BLEMMER 70ANEP-550, etc., and Kyoeisha Chemical Co., Ltd. light ester MC, light ester 130MA, light ester 041MA, light acrylate BO-A, light acrylate EC-A, light acrylate MTG-A, light acrylate 130A, light Acrylate DPM-A, light acrylate P-200A, light acrylate NP-4EA, light acrylate NP-8EA and the like can be mentioned, and these can be selected and used.

  Other than acrylic monomers, acrylimides typically include diacetone acrylamide, acrylamide, N-isopropyl acrylamide (NIPAM), N-ethyl acrylamide, N-pyrrolidinyl acrylamide, N-cyclopropyl acrylamide, N -Diethylacrylamide, N-methyl, N-isopropylacrylamide, N-propylacrylamide, N-methyl, N-isopropylpropylacrylamide, N-piperidinylacrylamide, N-propylacrylamide and the like.

  Examples of vinyl monomers other than acrylic monomers include vinyl alcohol and vinyl acetate.

  By copolymerizing these monomers at an arbitrary ratio, the hydrophilicity and hydrophobicity of the polymer can be controlled.

  The molecular weight of the polymer is not particularly limited, but is preferably 10,000 or more and 500,000 or less.

(Thermoplastic resin)
Next, the thermoplastic resin used in the present invention will be described.

  A thermoplastic resin is a resin that becomes soft when heated to the glass transition temperature or melting point and can be molded into the desired shape. In general, thermoplastic resins are often difficult to machine such as cutting and grinding, and when heated and softened, they are widely used for injection molding, etc., which is pushed into a mold and cooled and solidified to make the final product. ing.

  Examples of the thermoplastic resin include the following as general-purpose plastics that are generally abundant in types that are commercially available. Polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), Teflon (registered trademark) (Polytetrafluoroethylene, PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), and the like.

  When strength and resistance to breakage are particularly required, the following may be mentioned.

Polyamide (PA), nylon, polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate ( GF-PET), cyclic polyolefin (COP)
Etc.

  When higher heat distortion temperature and long-term use characteristics are required, the following can be mentioned. Polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyetheretherketone, thermoplastic polyimide (PI), polyamideimide (PAI), etc. .

  Although these general resins are abundant in types, there are many commercially available products of the same type and different molecular weights, so combinations of types and molecular weights should be performed according to the application of the present invention. Is possible.

  Particularly preferred thermoplastic resins include polyethylene terephthalate (PET), polycarbonate (PC), and acrylic resin (PMMA).

  The molecular weight of the thermoplastic resin can be measured by a conventionally known method.

  Specifically, 1 ml of THF (using a degassed sample) is added to 1 mg of a measurement sample, and the sample is stirred using a magnetic stirrer at room temperature to be sufficiently dissolved. Subsequently, after processing with a membrane filter having a pore size of 0.45 μm to 0.50 μm, it is injected into a GPC (gel permeation chromatograph) apparatus.

  GPC measurement conditions are measured by stabilizing the column at 40 ° C., flowing THF (tetrahydrofuran) at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml.

  As the column, it is preferable to use a combination of commercially available polystyrene gel columns. For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard, etc. manufactured by Tosoh Corporation A combination of these is preferred.

  As the detector, a refractive index detector (RI detector) or a UV detector is preferably used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points are preferably used as polystyrene for preparing a calibration curve.

  In the present invention, the molecular weight was measured under the following measurement conditions.

(Measurement condition)
Equipment: Tosoh High Speed GPC Equipment HLC-8220GPC
Column: TOSOH TSKgel Super HM-M
Detector: RI and / or UV
Eluent flow rate: 0.6 ml / min Sample concentration: 0.1% by mass
Sample volume: 100 μl
Calibration curve: prepared with standard polystyrene: standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500-500 calibration curves (also referred to as calibration curves) were used to calculate the molecular weight. . It is preferable that the 13 samples are substantially equally spaced.

  For those having a molecular weight range of 1500 or more, the molecular weight was measured by the above method.

  For those having a molecular weight range of less than 1500, the molecular weight measured by a mass spectrometer was employed. The molecular weight can be obtained from the mass number of the parent peak in the measurement using a mass spectrometer (GCMS-QP2010 Plus, manufactured by Shimadzu Corporation).

(Method for producing cellulose fiber-containing resin material)
The cellulose fiber-containing resin material production method according to the present invention includes a cellulose fiber defibrating step in which one type of cellulose fiber or one or more types of cellulose fibers are uniformly dispersed in a solvent in a nanometer order in a solvent, and a defibrating step. After that, the cellulose fiber and the thermoplastic resin are composed of a surface treatment step for hydrophobizing the surface of the cellulose fiber and a kneading step for kneading the surface-treated hydrophobic cellulose fiber and the thermoplastic resin. A kneading step for mixing the surface-treated cellulose fiber, the organic solvent and the first thermoplastic resin, and a second thermoplastic resin having a molecular weight larger than that of the first thermoplastic resin. A second mixing step of further mixing.

  The content of the surface-treated cellulose fiber with respect to the thermoplastic resin is 1% to 60% by volume, preferably 2% to 50%, more preferably 3% to 40%.

(First mixing step)
The surface-treated cellulose fiber used in the present invention is mixed with a first thermoplastic resin having a molecular weight lower than that of the second thermoplastic resin used in the second mixing step in advance as a second (final) The compatibility with the thermoplastic resin is improved, and uniform dispersion becomes possible. The step of mixing the low-molecular-weight first thermoplastic resin as a binder before mixing with the second (final) thermoplastic resin is referred to as a first mixing step. What is used as a binder is suitably used in consideration of the affinity with the final second thermoplastic resin and the dispersibility of cellulose fibers.

  The molecular weight of the first plastic resin used in the first mixing step is preferably 500 or more and 50000 or less, and more preferably 1500 or more and 50000 or less.

  In consideration of the affinity with the second thermoplastic resin (thermoplastic resin in the second mixing step) and the dispersibility of the cellulose fibers, the (first) thermoplastic resin in the first mixing step is usually the second mixture. It is preferable to use the same composition as that of the (second) thermoplastic resin in the step. However, if the affinity with the second thermoplastic resin (the thermoplastic resin in the second mixing step) and the dispersibility of the cellulose fibers are good, the composition of the thermoplastic resin in the first mixing step and the second mixing step Need not be the same.

  In the first mixing step, the wet mixing method is desirable from the viewpoint that the thermoplastic resin and the surface-treated cellulose fiber are less damaged and can be uniformly mixed. Other advantages of the wet mixing method include prevention of powder scattering, operational convenience, and improved dispersibility. However, the amount of solvent or solution specifically used is appropriately selected depending on the thermoplastic resin used and the surface-treated cellulose fiber.

  The applicable solvent may be any solvent that can dissolve the first thermoplastic resin in the first mixing step and maintain the dispersibility of the surface-treated cellulose fiber, such as benzene, toluene, xylene, and the like. Aromatic hydrocarbons, ketones such as acetone, methyl ethyl ketone, cyclohexanone, heptanone, esters such as ethyl acetate, acetic acid-t-butyl, acetic acid-n-butyl, acetic acid-n-hexyl, 1,2-dichloroethane, chloroform Halogenated hydrocarbons such as chlorobenzene, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, etc. Ethers, N, N- dimethylformamide, N, N- dimethylacetamide, dimethyl sulfoxide, can be mentioned N- methyl-2-pyrrolidone, sulfolane, aprotic polar solvents such as acetonitrile.

In addition, the protic solvent is a solvent having a proton donating property, and many proton solvents have hydrogen with relatively high acidity bonded to oxygen or nitrogen atoms, and at the same time, oxygen or nitrogen has a lone pair of electrons. It is a solvent that also has the property of accepting protons (Lewis basic). Protic solvents are also solvents that form hydrogen bonds between solvent molecules. Specific examples include glycols such as methanol, ethanol, propanol, butanol, acetic acid, ethylene glycol, and propylene glycol (glycolic acid, glyoxylic acid, diethylene glycol, polyethylene glycol, glycol aldehyde, glyoxal) and the like. These solvents can be used alone or in admixture of two or more.

In particular, an organic solvent containing a hydroxyl group is preferable , and glycols such as methanol, ethanol, propanol, butanol, acetic acid, ethylene glycol, and propylene glycol are preferable in that the cellulose fibers are uniformly dispersed in the resin.

  Regarding the boiling point of the solvent used at atmospheric pressure, it is preferably 30 ° C. or higher and 200 ° C. or lower, more preferably 50 ° C. or higher and 150 ° C. or lower. When the boiling point is less than 30 ° C., it is dangerous in handling. On the other hand, if the boiling point is higher than 200 ° C., it is difficult to remove the solvent, and the final product is adversely affected by the residue of the decomposition product and heating.

  The amount of the solvent used when carrying out the first mixing step of the present invention is not particularly limited as long as the thermoplastic resin in the first mixing step is dissolved, but 100 mass of the thermoplastic resin in the first mixing step. The solvent is preferably 100 to 2000 parts by mass with respect to parts. When the solvent is less than 100 parts by mass, the thermoplastic resin in the first mixing step is not completely dissolved, and the composition of the cellulose fiber thermoplastic resin composite material in the first mixing step may be nonuniform. In the case of over 2000 parts by mass, productivity is lowered and sufficient torque cannot be obtained during wet mixing, and the composition of the cellulose fiber thermoplastic resin composite material may become non-uniform.

  If there is residual solvent at the start of the second mixing step, equipment for removing the solvent must be introduced in the middle of the second mixing step, which increases the equipment cost and is removed by the end of the first mixing step. Is desirable. Although the solvent may be removed in the solvent removal step after the completion of the first mixing step, it is preferable to remove the solvent during the first mixing step from the viewpoint of increasing production time and drying equipment.

  Known devices such as a twin-screw kneader, tumbler mixer, super mixer, Henschel mixer, screw blender, and ribbon blender can be used as the first mixing device while removing the solvent. It is desirable to use a twin-screw kneader that is easy and can continuously produce materials. Moreover, when performing by a batch type, when high torque type kneaders, such as TK high vis mix by a Primix company, are used, it is possible to mix a high-viscosity substance from a powder, and solvent removal is also easy.

  As temperature at the time of the process of a 1st mixing process, 20 to 300 degreeC is preferable, More preferably, 40 to 250 degreeC is good.

  Moreover, as a thermoplastic resin to add, 0.1 mass% or more and 50 mass% or less of a cellulose fiber are preferable, and 0.1 mass% or more and 50 mass% or less of the thermoplastic resin added at a 2nd mixing process are preferable.

(Second mixing step)
In the second mixing step, a cellulose fiber thermoplastic resin composite material prepared in the first mixing step is added to the target thermoplastic resin and kneaded to produce a composite material, or a thermoplastic dissolved in a solvent. A preferred embodiment is a production method in which a composite material is prepared by mixing a resin and a cellulose fiber thermoplastic resin composite material and then removing the organic solvent.

  In the second mixing step, the final composite material is particularly preferably produced by a kneading method.

  In the second mixing step, it is possible to use an organic solvent. In that case, it is preferable to deaerate after kneading to remove the organic solvent from the composite material.

  Examples of the apparatus that can be used for the kneading in the second mixing step include a closed kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, and a roll, or a batch kneading apparatus. Moreover, it can also manufacture using a continuous kneading apparatus like a single screw extruder, a twin screw extruder, etc.

  First, in a kneader equipped with an extension flow kneading chamber as shown in FIG. 1 in the resin discharge section, the second thermoplastic resin in the second mixing step is melted, After the prepared cellulose fiber thermoplastic resin composite material is added and melt kneaded to disperse it in the second thermoplastic resin in the second mixing step, the molten composite material is extruded into a strand and pellets There is also a way to make it.

  When a kneading machine is used as the treatment mode of the second mixing step, the thermoplastic resin and the cellulose fiber thermoplastic resin composite material prepared in the first mixing step may be added and kneaded all at once, or added in stages. And may be kneaded. In this case, in a kneading apparatus such as an extruder, it is possible to add the components to be added step by step from the middle of the cylinder. In the kneading process, it is preferable to add a light-resistant stabilizer in the later step as much as possible. Therefore, at least a part of the light-resistant stabilizer is added after the addition of the cellulose fiber thermoplastic resin composite material prepared in the first mixing step.

  When the second thermoplastic resin and the cellulose fiber thermoplastic resin composite material prepared in the first mixing step are combined by kneading, the cellulose fiber thermoplastic resin composite material prepared in the first mixing step is powdered or agglomerated. It can be added as it is. Alternatively, the cellulose fiber thermoplastic resin composite material prepared in the first mixing step can be added in a state of being dispersed in the liquid. In the case where the cellulose fiber thermoplastic resin composite material prepared in the first mixing step is added in a state dispersed in a liquid, it is preferable to perform deaeration after kneading.

  When the cellulose fiber thermoplastic resin composite material prepared in the first mixing step is added in a state of being dispersed in the liquid, it is preferable that the aggregated fibers are uniformly dispersed and added in advance. Various dispersing machines can be used for dispersion, but a bead mill is particularly preferable. There are various materials for beads, but those having a small size are preferable, and those having a diameter of 0.001 to 0.1 mm are particularly preferable.

  Furthermore, you may add a 3rd, 4th thermoplastic resin by the method similar to this 2nd mixing process.

  The thermoplastic resin in the second mixing step corresponds to a thermoplastic resin having a large molecular weight, and a molecular weight of 50,000 to 1,000,000 is preferably used from the viewpoint of resin strength and moldability.

  As temperature at the time of the process of a 2nd mixing process, 20 degreeC or more and 300 degrees C or less are preferable, More preferably, 40 degreeC or more and 250 degrees C or less are good.

  As addition amount of a thermoplastic resin, the density | concentration of a cellulose fiber is 1 mass% or more and 30 mass% with respect to the total amount of the 1st thermoplastic resin of a 1st mixing process, and the 2nd thermoplastic resin of a 2nd mixing process. It is preferable that More preferably, they are 3 mass% or more and 20 mass% or less.

(Molecular weight of the thermoplastic resin in the first mixing step and the second mixing step)
Regarding the respective molecular weights of the first thermoplastic resin and the second thermoplastic resin used in the first mixing step and the second mixing step, respectively, a detailed description will be given in the first mixing step and the second mixing step. Is going. The ratio of the molecular weight of the first thermoplastic resin in the first mixing step and the second thermoplastic resin in the second mixing step is (molecular weight of the first thermoplastic resin / molecular weight of the second thermoplastic resin) is 1. / 1000 or more and less than 1/1. In the case of 1/1000 or less, uniform dispersion of cellulose fibers becomes difficult. On the other hand, when the ratio is 1/1 or more, the molding of the base material resin becomes worse. The ratio is more preferably 1/1000 or more and 1/2 or less. In this case, the effect of the present invention, which can significantly improve the mechanical properties of the resin, is obtained.

(Additive)
In addition, when using the composite material which concerns on this invention for the optical resin material, and when using it as an optical element, you may add various additives as needed. Examples of such additives include antioxidants, light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as ultraviolet absorbers and near infrared absorbers, lubricants, resin modifiers such as plasticizers, soft polymers, , Anti-clouding agents such as alcoholic compounds, colorants such as dyes and pigments, other antistatic agents, flame retardants and the like. They may be used alone or in combination.

<Antioxidant>
Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. By blending these antioxidants, coloring and strength reduction due to oxidative degradation during molding of the composite material can be prevented without reducing transparency, heat resistance, and the like.

  As the phenolic antioxidant, conventionally known ones can be applied. For example, 2-t-butyl-6- (3-t-butyl-2-hydroxy- described in JP-A No. 63-179953). 5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate, etc. Acrylate compounds such as octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate described in JP-A-1-168463, and 2,2′-methylene-bis (4-methyl) -6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-to (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenylpropionate)) methane, , Pentaerythrmethyl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)), triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5- Alkyl-substituted phenolic compounds such as methylphenyl) propionate), 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4- Bisoctylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3 - triazine group-containing phenol compounds such as triazine.

  The phosphorus-based antioxidant is not particularly limited as long as it is a substance that is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris ( Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl)- Monophosphite compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di- Tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C 5) phosphite) diphosphite compounds such as and the like. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  Examples of the sulfur-based antioxidant include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodiprote. Pionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Can be mentioned.

  Furthermore, in addition to the above-mentioned phenol-based, phosphoric acid-based and sulfur-based antioxidants, amine-based antioxidants such as diphenylamine derivatives, nickel or zinc thiocarbamates, and the like are also applicable as antioxidants.

  The above-mentioned antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention. The amount is preferably in the range of 0.001 to 20 parts by mass, more preferably in the range of 0.01 to 10 parts by mass with respect to parts.

<Anti-clouding agent>
As the cloudiness inhibitor, a compound having the lowest glass transition temperature of 30 ° C. or less can be blended. This prevents the cloudiness of the thin film in the long-time high-temperature and high-humidity environment without degrading various properties such as transmittance, heat resistance, and mechanical strength, and in the long-time high-temperature and high-humidity environment. it can.

<Light stabilizer>
Light-resistant stabilizers (light stabilizers) are roughly classified into quenchers and radical scavengers. Benzophenone light stabilizers, benzotriazole light stabilizers, and triazine light stabilizers are classified as quenchers, and hindered amine light stabilizers are classified as radical scavengers. In the present invention, it is preferable to use a hindered amine light stabilizer (HALS) from the viewpoint of the transparency of the lens, the color resistance, and the like. Specific examples of such HALS can be selected from low molecular weight to medium molecular weight and high molecular weight.

  For example, LA-77 (manufactured by Asahi Denka), Tinuvin 765 (manufactured by Ciba Japan), Tinuvin 123 (manufactured by Ciba Japan), Tinuvin 440 (manufactured by Ciba Japan), Tinuvin 144 (manufactured by Ciba Japan) , Hostavin N20 (Hoechst) medium molecular weight LA-57 (Asahi Denka), LA-52 (Asahi Denka), LA-67 (Asahi Denka), LA-62 (Asahi Denka), LA-68 (Asahi Denka), LA-63 (Asahi Denka), Hostavin N30 (Hoechst), Chimassorb 944 (Ciba Japan), Chimassorb 2020 (Ciba Japan), Chimassorb 119 (Ciba)・ Made in Japan), Tinubi 622 (manufactured by Ciba Japan), CyasorbUV-3346 (manufactured by Cytec), CyasorbUV-3529 (manufactured by Cytec), and the like Uvasil299 (manufactured by GLC). In particular, it is preferable to use low and medium molecular weight HALS for a composite material (using an optical element) and high molecular weight HALS for a film-like composite material.

  HALS is also preferably used in combination with a benzotriazole-based light-resistant stabilizer. For example, ADK STAB LA-32, LA-36, LA-31 (manufactured by Asahi Denka Kogyo), Tinuvin 326, Tinuvin 571, Tinuvin 234, Tinuvin 1130 (manufactured by Ciba Japan) and the like can be mentioned.

  HALS is preferably used in combination with the various antioxidants described above. There are no particular restrictions on the combination of HALS and antioxidant, and combinations of phenols, phosphorus, sulfur and the like are possible, but combinations of phosphorus and phenols are particularly preferred.

<Other additives>
In addition to the above-mentioned antioxidants and light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as near infrared absorbers, resin modifiers such as lubricants and plasticizers, soft polymers, white turbidity such as alcoholic compounds Inhibitors, coloring agents such as dyes and pigments, antistatic agents, flame retardants and the like can be mentioned. These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects described in the present invention.

  The final composite material thus manufactured may be used as a molded body such as an optical lens or may be used in a film-like film form.

  In addition, the cellulose fiber of the present invention can ensure transparency, but even if it is used as a colored molded body or film, the heat resistance and mechanical strength can be drastically improved compared to a single resin, Deployment is also possible.

  The evaluation method of the cellulose fiber thermoplastic resin composite material according to the present invention will be described below.

(Method of evaluating cellulose fiber thermoplastic resin composite material)
(1) Tensile strength A test piece for measuring physical properties was prepared and subjected to a tensile test using a tensile tester of Twin Column Model 3360 series manufactured by Instron. The length of the test piece was 5 cm, the width was 1 cm, the thickness was 2 mm, and the pulling speed was 1 cm per minute.
(2) Bending elastic modulus and bending strength A fiber composite material formed into a plate shape is prepared and cut out at 140 mm × 12 mm × 2 mm, and the distance between fulcrums is 80 mm, bending speed by autograph (“DSS-500” manufactured by Shimadzu Corporation). The bending elastic modulus and bending strength were measured at 2 mm / min and 20 ° C.
(3) Linear expansion coefficient About the molded object, temperature was changed within the range of 40-80 degreeC, and the linear expansion coefficient was measured. SII (Seiko Instruments) EXSTAR6000 TMA / SS6100 was used as a measuring device. The test piece was 1 cm in length, 1 cm in width, and 2 mm in thickness.
(4) Heat resistance (measurement of glass transition point (Tg))
The glass transition point of the composite material was measured using a high-sensitivity differential scanning calorimeter (DSC SII Nanotechnology Inc.).
(5) Measurement of light transmittance Using a spectrophotometer (visible ultraviolet spectrophotometer UV-2500PC, Shimadzu Corporation), the total transmitted light amount with respect to the incident light amount of visible light was measured according to ASTM D-1003 standard. The measurement result at 550 nm was used.
(6) Dispersibility evaluation of cellulose fiber in composite material For each sample, the dispersity of cellulose fiber having a fiber diameter of 2 nm or more and 200 nm or less was visually observed with a transmission electron microscope (hereinafter referred to as TEM) image. Evaluation was performed.

  An ultrathin section having a thickness of 0.1 to 0.2 μm is prepared using a diamond knife, and the ultrathin section is supported on a copper mesh and transferred onto a carbon film that has been hydrophilized by glow discharge. While cooling to −130 ° C. or lower with nitrogen, a bright field image was observed with a TEM at a magnification of 5,000 to 40,000 and quickly recorded on a CCD camera. The carbon film was an extremely thin collodion organic film, the TEM acceleration voltage was 150 kV, and a TEM image recorded was visually observed to evaluate dispersibility. ○ was classified as good dispersibility, Δ was slightly aggregated, and × was severely aggregated. The two listed are judged to be intermediate states.

  Examples of the present invention are shown below, but the present invention is not limited to these Examples.

<About cellulose fiber>
(Comparative Example 1)
Sulfuric acid bleached pulp obtained from conifers is added to 1.0% by mass in pure water, and cellulose fibers are defibrated using an Excel Auto Homogenizer manufactured by Nippon Seiki Seisakusho Co., Ltd. for 15 minutes at 3000 rpm. did. This aqueous dispersion was designated as cellulose fiber A. From the observation result of the scanning electron microscope, it was confirmed that the obtained cellulose fiber was fibrillated to an average fiber diameter of 250 nm and was microfibrillated.

(Comparative Example 2)
The cellulose fiber A aqueous dispersion prepared in Comparative Example 1 was filtered, washed with pure water, and dried at 70 ° C. to obtain cellulose fiber B.

  To 100 parts by mass of acetone, 5 parts by mass of cellulose fiber B is added and dispersed. While stirring this dispersion at the boiling reflux temperature, a mixture of 5 parts by mass of acetic anhydride is added over 60 minutes, and then further. Stir for 2 hours. From the result of observation with a scanning electron microscope, the obtained cellulose fiber was kept at an average fiber diameter of 250 nm. The obtained sample was designated as cellulose fiber C.

(Production Example 1)
A cellulose fiber D was prepared in the same manner except that the rotation speed of Comparative Example 1 was changed to 15 minutes at 10,000 rotations / minute. It was confirmed that the fiber was fibrillated to an average fiber diameter of 200 nm and microfibrillated.

(Production Example 2)
The cellulose fiber D aqueous dispersion prepared in Production Example 1 was filtered, washed with pure water, and dried at 70 ° C. to obtain cellulose fiber E.

  To 100 parts by mass of ethanol and 1 part by mass of pure water, 5 parts by mass of cellulose fiber E is added and dispersed. While stirring this dispersion at 50 ° C., a mixture of 5 parts by mass of tetraethoxysilane is taken over 60 minutes. And then stirred for another 2 hours. From the result of observation with a scanning electron microscope, the obtained cellulose fiber was kept at an average fiber diameter of 200 nm. The obtained sample was designated as cellulose fiber F.

(Production Example 3)
Disperse 100 parts by mass of the cellulose fiber D aqueous dispersion prepared in Production Example 1, add 10 parts by mass of acetic anhydride over 60 minutes while stirring this dispersion at 100 ° C., and then further 2 hours Stir. Further, the solvent was removed by a rotary evaporator, and the cellulose fiber obtained with the cellulose fiber concentration of 5% by mass as the end point was found to have an average fiber diameter of 200 nm from the result of observation with a scanning electron microscope. It was. The obtained sample was designated as cellulose fiber G.

(Production Example 4)
Cellulose fiber D prepared in Production Example 1 was dispersed with Ultra Apex Mill UAM-015 (manufactured by Kotobuki Industries Co., Ltd.) using 0.5 mm beads for 1 hour at a peripheral speed of 6 m / sec. The cellulose fiber H was adjusted with water so that the cellulose fiber D might be 1 mass%, and the cellulose fiber H was obtained. The obtained cellulose fiber had an average fiber diameter of 50 nm.

(Production Example 5)
Cellulose fibers H prepared in Production Example 4 were surface treated in the same manner as in Production Example 3 to obtain cellulose fibers I. The obtained cellulose fiber had an average fiber diameter of 50 nm.

(Production Example 6)
The cellulose fiber D produced in Production Example 1 was pulverized 180 times at 200 MPa with a high-pressure pulverization system Altemizer HJP-2005 (manufactured by Sugino Machine Co., Ltd.). The cellulose fiber D was adjusted with water so that the cellulose fiber D might be 1 mass%, and the cellulose fiber J was obtained. The obtained cellulose fiber had an average fiber diameter of 10 nm.

(Production Example 7)
Cellulose fibers J prepared in Production Example 6 were surface treated in the same manner as in Production Example 3 to obtain cellulose fibers K. The obtained cellulose fiber had an average fiber diameter of 10 nm.

(Production Example 8)
Cellulose fibers D prepared in Production Example 1 were mixed with 1 g of dry mass, 0.0125 g of TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) and 0.125 g of sodium bromide in water. After dispersing in 100 ml, sodium hypochlorite was added to a 13 mass% sodium hypochlorite aqueous solution so that the amount of sodium hypochlorite was 2.5 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10.5. When the change in pH is no longer observed, the reaction is considered to be complete, the reaction product is filtered through a glass filter, washed with a sufficient amount of water and filtered five times, so that the cellulose fiber D is 0.1% by mass. Diluted with water. Furthermore, it processed with the ultrasonic disperser for 1 hour and the cellulose fiber L was obtained. It was the average fiber diameter of 4 nm.

(Production Example 9)
Cellulose fibers L prepared in Production Example 8 were surface treated in the same manner as in Production Example 3 to obtain cellulose fibers M. The obtained cellulose fiber had an average fiber diameter of 4 nm.

  In the following, samples of Comparative Examples 1 and 2, Production Examples 1 to 9 using a solvent different in type from the first mixing step are gradually replaced by a membrane separation method, and the concentration of cellulose fibers is 10 Solvent substitution was performed so that the mass%.

<First mixing step of cellulose fiber and thermoplastic resin of Comparative Examples 1 and 2 Production Examples 1 to 9>
Cellulose fibers and thermoplastic resins (described in Table 1) were mixed in equal amounts in the solvents shown in Table 1 in accordance with the composition described in Table 1. After mixing at 60 ° C. for 3 hours using a TK high-vis mix manufactured by Plymix as a high-torque kneader, the inside of the apparatus was evacuated and dried to obtain a powdery sample. Moreover, in the sample of Table 1, it sent to the 2nd mixing process, without vacuum-drying.

<Second mixing step after the first mixing step>
The addition amount of the thermoplastic resin used for a cellulose fiber and a 2nd mixing process was adjusted so that it might become a mixing | blending composition shown in Table 1, and the 2nd mixing process was performed. The second mixing step was performed by first melting the thermoplastic resin and then adding the sample prepared in the first mixing step. Further, as a high-torque type kneader, a kneader equipped with the extension flow kneading chamber shown in FIG. 1 is used in the molten resin discharge section, and melt kneading is performed at a barrel temperature of 250 ° C. and a discharge rate of 10 kg / h. The resin discharged from the tip was cut into pellets to obtain final composite material pellets. The obtained pellets were vacuum-dried at 70 ° C. for 24 hours, and then used for measuring physical properties of the above-mentioned sizes, for example, 140 mm × 12 mm ×, using an injection molding machine (IS-80G type manufactured by Toshiba Machine Co., Ltd.). 2 mm was produced and used for various measurements. The evaluation results are shown in Table 1.

  For samples not dried in the first mixing step, the solvent is volatilized from the vent port in the middle of mixing in the kneading machine in the second mixing step (vent exhaust), and the resin discharged from the tip of the extruder is solvent Was not left behind.

  Table 1 shows the composition of the composite material sample, each condition of the first mixing step and the second mixing step, and Table 2 shows the evaluation results of each composite material sample. Each evaluation method is as described above.

In addition,
TEOS: Tetraethoxysilane EG: Ethylene glycol PET: Polyethylene terephthalate PC: Polycarbonate 1 and 29 are single polymers.

  From Table 1, it was found that the present invention can improve the mechanical strength of the base material resin while maintaining transparency and reduce the linear expansion. Furthermore, it was surprisingly found that as a composite material, the glass transition temperature of the matrix resin can be raised to impart heat resistance. As a result, a low-priced resin represented by PET can be made highly functional, and a great contribution to the industrial field can be expected.

DESCRIPTION OF SYMBOLS 1 Elongation flow kneading chamber 2 Elongation flow kneading part 2a 1st flow path 2b 1st slit flow path 2c 2nd flow path 2d 2nd slit flow path 3 Resin composition supply port 4 Resin composition discharge port

Claims (5)

  A method for producing a resin material comprising a thermoplastic resin and a surface-treated cellulose fiber having an average fiber diameter of 2 nm or more and 200 nm or less, wherein the surface-treated cellulose fiber, an organic solvent, and a first thermoplastic resin A method for producing a cellulose fiber-containing resin material, comprising: a first mixing step of mixing, and a second mixing step of further mixing a second thermoplastic resin having a molecular weight larger than that of the first thermoplastic resin.   The molecular weight of the first thermoplastic resin mixed in the first mixing step is 500 or more and 50,000 or less, and the molecular weight of the second thermoplastic resin mixed in the second mixing step is 50,000 or more and 1,000,000 or less. The manufacturing method of the cellulose fiber containing resin material of Claim 1 characterized by these.   The method for producing a cellulose fiber-containing resin material according to claim 1 or 2, wherein the concentration of the cellulose fiber at the end of the second mixing step is 1% by mass or more and 30% by mass or less with respect to the total amount of the resin. .   The said organic solvent contains the hydroxyl group, The manufacturing method of the cellulose fiber containing resin material of any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a cellulose fiber-containing resin material according to any one of claims 1 to 4, wherein the organic solvent is removed after the first mixing step and then the second mixing step is performed.