JP2011122014A - Resin composite, method for producing the same, and method for producing cellulose nanofiber used in the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composite using cellulose nanofibers with a narrow fiber diameter distribution and having a small linear expansion coefficient and excellent transparency, a method for producing the same, and a method for producing cellulose nanofibers for the same. <P>SOLUTION: The resin composite contains cellulose nanofibers, wherein the cellulose nanofibers are a surface-acylated plant-derived cellulose fiber aggregate and have a degree of I<SB>β</SB>crystallization in a range of 40-60%, an average fiber diameter in a range of 4-200 nm and a coefficient of variation (S/Da) which is a ratio between the average fiber diameter Da and its standard derivation S in a range of less than 0.15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin composite having a small linear expansion coefficient and excellent transparency, a method for producing the same, and a method for producing cellulose nanofibers used therefor.

  Cellulose is the most abundant natural polymer on the earth and has been used in various forms. It has been used in many industrial fields as a fiber, but recently, research related to cellulose nanofibers has been conducted. It is thriving. This is a very useful fiber such as a nano-sized fiber (ultrafine fiber) with a small fiber diameter, and its fiber aggregate has a very large surface area per unit mass, and has excellent separation performance and liquid retention performance. It is because it has a characteristic.

  On the other hand, research and development of highly functional composite materials such as fiber reinforced composite materials that take advantage of the characteristics of cellulose nanofibers are also becoming active.

  Regarding cellulose, several production methods for obtaining nano-sized ultrafine fibers have been proposed so far. For example, Patent Document 1 discloses a method for obtaining fine cellulose fibers by utilizing a surface oxidation reaction of cellulose by an N-oxyl compound. Patent Document 2 discloses a method for producing an ultrafine cellulose fiber having a nano-sized fiber diameter excellent in uniformity and a fiber aggregate thereof by using an electrostatic spinning method of a cellulose solution. Patent Document 3 discloses a highly transparent fiber-reinforced composite material obtained by impregnating a resin into a cellulose fiber aggregate having an average fiber diameter of 4 to 200 nm, and a method for producing the same.

  However, cellulose nanofibers obtained by the production methods disclosed in the above-mentioned patent documents and the like have a large distribution of fiber diameters and are non-uniform or have good uniformity, but have a high production cost. When used, there were problems such as insufficient performance such as transparency.

JP 2008-1728 A JP 2008-266828 A JP 2007-51266 A

  The present invention has been made in view of the above-mentioned problems and situations, and its solution is a resin composite using cellulose nanofibers with a small fiber diameter distribution, which has a low linear expansion coefficient and transparency. It is to provide an excellent resin composite and a production method thereof. Moreover, it is providing the manufacturing method of the cellulose nanofiber for that.

  The problems according to the present invention are solved by the following means.

1. A resin composite containing cellulose nanofibers, wherein the cellulose nanofibers are plant-derived cellulose fiber aggregates whose surfaces are subjected to acylation treatment, and the I _β type crystallinity is 40 to 60%. The average fiber diameter is in the range of 4 to 200 nm, and the coefficient of variation (S / Da), which is the ratio of the average fiber diameter Da and its standard deviation S, is within 0.15. Characteristic resin composite.

  2. The method for producing a resin composite according to claim 1, wherein the acylation treatment is an acylation treatment by a gas phase surface treatment method or a supercritical region surface treatment method. A method for producing a resin composite.

  3. A method for producing cellulose nanofibers contained in the resin composite according to item 1, wherein the freeze-dried cellulose nanofibers are acylated by a gas phase surface treatment method. Production method.

  4). A method for producing cellulose nanofibers contained in the resin composite according to item 1, wherein the cellulose nanofibers are freeze-dried and acylated by a supercritical region surface treatment method. Manufacturing method.

  5. The method for producing cellulose nanofibers contained in the resin composite according to item 1, wherein the cellulose nanofibers subjected to acylation treatment are heated by infrared rays and stretched by 100 times or more. The manufacturing method of the cellulose nanofiber of the 3rd term or the 4th term.

  6). A method for producing cellulose nanofibers contained in a resin composite, wherein the cellulose nanofibers subjected to acylation treatment are heated with infrared rays and stretched 100 times or more.

  By the above means of the present invention, it is possible to provide a resin composite using cellulose nanofibers having a small fiber diameter distribution, a low linear expansion coefficient and excellent transparency, and a method for producing the same. . Moreover, the manufacturing method of the cellulose nanofiber for that can be provided.

Process conceptual diagram of the method for drawing raw cellulose nanofibers Example of arrangement of mirrors for irradiating cellulose nanofibers with infrared rays from multiple locations; A is a plan view, B is a side view Schematic flow sheet showing one embodiment of an apparatus for producing a film-like resin composite

The resin composite of the present invention is a resin composite containing cellulose nanofibers, wherein the cellulose nanofibers are plant-derived cellulose nanofiber aggregates whose surfaces are acylated, and I _β The coefficient of variation (S / Da) is the ratio of the average fiber diameter Da and its standard deviation S, and the type crystallinity is in the range of 40 to 60%, the average fiber diameter is in the range of 4 to 200 nm Is within 0.15. This feature is a technical feature common to the inventions according to claims 1 to 6.

  In the method for producing a resin composite of the present invention, the acylation treatment is preferably an acylation treatment by a gas phase surface treatment method or a supercritical region surface treatment method.

  Moreover, as a manufacturing method of the cellulose nanofiber contained in the resin composite of this invention, the manufacturing method of the aspect which acylates the freeze-dried cellulose nanofiber by a gaseous-phase surface treatment method, or a freeze-dried cellulose nanofiber It is preferable that the method is a production method in which the fiber is acylated by a supercritical region surface treatment method. Furthermore, it is preferable that the cellulose nanofibers subjected to the acylation treatment are heated by infrared rays and stretched 100 times or more.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail.

<Cellulose nanofiber>
The cellulose nanofiber according to the present invention is a cellulose nanofiber derived from a plant and is characterized in that it is a cellulose-based fiber having an average fiber diameter in the range of 4 to 200 nm. Here, the cellulosic fiber refers to a microfibril of cellulose constituting the basic skeleton of a plant cell wall or the like, or a component fiber thereof, and is usually an aggregate of unit fibers having a fiber diameter of about 4 nm. In addition, the cellulose nanofiber which concerns on this invention requires that I ( _beta) type crystallinity is in the range of 40 to 60%.

By the way, there are two types of crystals of natural cellulose, namely, triclinic cellulose I _α (Cellulose I _α , also simply referred to as “I _α ” hereinafter) and monoclinic cellulose I _β (Cellulose I). _β , hereinafter also simply referred to as “I _β ”). The abundance ratio of both crystals varies significantly depending on the type of natural cellulose. For example, Varo in the near cellulose, whereas I _alpha is about 64% and I _alpha is rich, the cotton or ramie cellulose, I _beta is about 80% and I _beta is rich. Moreover, Hoya cellulose is composed of only little I _beta. On the other hand, bacterial cellulose, Varo near cellulose Like content of I _alpha is 64%.

  Cellulose nanofibers according to the present invention may be composed of single fibers that are sufficiently spaced apart so as to enter each other. In this case, the average fiber diameter is the average diameter of single fibers. Further, the fibers according to the present invention may be one in which a plurality of (may be many) single fibers are gathered in a bundle to form one yarn. The average fiber diameter is defined as the average value of the diameter of one yarn.

  The average fiber diameter of the fiber used in the present invention is 4 to 200 nm, preferably 4 to 60 nm.

  In addition, as long as the fiber used by this invention has an average fiber diameter in the range of 4-200 nm, the thing of the fiber diameter out of the range of 4-200 nm may be contained in the fiber, The ratio is 30. Preferably, the fiber diameter of all the fibers is 200 nm or less, particularly 100 nm or less, particularly 60 nm or less.

  In addition, although it does not specifically limit about the length of a fiber, From a viewpoint of the reinforcement effect in a composite_body | complex, 100 nm or more is preferable by average length. In addition, although a fiber length less than 100 nm may be contained in the fiber, it is preferable that the ratio is 30 mass% or less.

  In the present invention, when the average fiber diameter is Da and the standard deviation is S, the coefficient of variation (S / Da) that is the ratio of Da to S is within 0.15.

  The uniformity of the fiber diameter of the cellulose nanofiber according to the present invention is the coefficient of variation (S / Da), which is the fiber diameter distribution of the fibers constituting the fiber assembly, that is, the ratio of the average fiber diameter Da to its standard deviation S. It is also called “CV value”). The coefficient of variation indicates that the smaller the value, the smaller the fiber diameter distribution, indicating a uniform fiber diameter. The coefficient of variation of the fiber aggregate of cellulose nanofibers according to the present invention is preferably 0.15 or less, and more preferably 0.10 or less.

  As a method for satisfying the coefficient of variation, cellulose nanofibers that have been subjected to acylation treatment after subjecting the surface of cellulose nanofibers described below to acylation treatment by vapor phase surface treatment method or supercritical region surface treatment method are used. It is preferable to adjust by a method of heating the glass with infrared rays and stretching it 100 times or more.

  In addition, the measurement of the said fiber diameter and fiber length can be measured with a commercially available microscope and an electron microscope. For example, by taking a photograph of cellulose nanofibers magnified 2000 times with a scanning electron microscope, and then analyzing the photographic image using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph It was measured. Under the present circumstances, the average value of a fiber diameter and fiber length can be calculated | required using 100 cellulose nanofibers.

  The cellulose nanofiber according to the present invention can be obtained, for example, by the method described in JP-A-2005-60680 and JP-A-2008-1728.

  The cellulose nanofibers of the present invention are preferably refined using a plurality of pulverizing means. The pulverizing means is not limited, but in order to finely pulverize to a particle size suitable for the purpose of the present invention, there is a method that can obtain a strong shearing force such as a high-pressure homogenizer, a media mill, a grindstone rotary grinder, and a stone mill grinder. Preferably used.

  A high-pressure homogenizer is a device that grinds by shear force due to accelerated high flow velocity, rapid pressure drop (cavitation), and impact force caused by high-velocity particles colliding face-to-face within a fine orifice, and is commercially available. As the device, a nanomizer (manufactured by Nanomizer Co., Ltd.), a microfluidizer (manufactured by Microfluidics) or the like can be used.

The degree of cellulose fibrillation and homogenization by the high-pressure homogenizer depends on the pressure fed to the high-pressure homogenizer and the number of passes (number of passes) passed through the high-pressure homogenizer. The pumping pressure is usually in the range of about 500 to 2000 kg / cm ^2, which is suitable for ultrafine processing, but 1000 to 2000 kg / cm ² is more preferable in consideration of productivity. The number of passes is, for example, about 5 to 50 times, preferably about 10 to 40 times, particularly about 20 to 30 times. The medium mill is a wet vibration mill, a wet planetary vibration mill, a wet ball mill, a wet roll mill, a wet coball mill, a wet bead mill, a wet paint shaker, or the like. Among these, for example, a wet bead mill is a device in which a metal or ceramic medium is built in a container and this is subjected to wet grinding by forcibly stirring it. A mill (manufactured by Kotobuki Giken Kogyo Co., Ltd.), a pearl mill (manufactured by Ashizawa Co., Ltd.), a dyno mill (manufactured by Shinmaru Enterprises Co., Ltd.), or the like can be used.

  The grindstone rotary grinder is a kind of colloid mill or stone mortar grinder, for example, grinds a grindstone made of abrasive grains having a particle size of 16 to 120 and passes the above-mentioned aqueous dispersion through the grinder. That is, it is an apparatus to be pulverized. You may perform a process in multiple times as needed. It is one of the preferred embodiments that the grindstone is appropriately changed. The grindstone rotary crusher has both “short fiber” and “fine” actions, but the action is affected by the grain size of the abrasive grains. For the purpose of shortening the fiber length, a # 46 or less grindstone is effective. For miniaturization purposes, a # 46 or greater grindstone is effective. No. 46 has both functions. Specific examples of the apparatus include a pure fine mill (grinder mill) (Kurita Machinery Co., Ltd.), a serendipeater, a super mass collider, and a super grinder (above, Masuko Sangyo Co., Ltd.).

  In the present invention, the obtained cellulose nanofibers are added to the thermoplastic resin directly or as a dispersion, and the content thereof is preferably in the range of 0.1 to 50% by mass. More preferably, it is 5-50 mass%, and especially 10-40 mass% is preferable.

  Although the method for containing cellulose nanofibers in acetylated cellulose is not particularly limited, it is preferably contained as a dispersion when preparing a dope solution in the solution casting method described below.

(Surface acylation treatment of cellulose nanofiber)
The acylation treatment method for the surface of the cellulose nanofiber according to the present invention is preferably an acylation treatment method by a gas phase surface treatment method or a supercritical region surface treatment method described later.

  In the acylation treatment of the surface of the cellulose nanofiber according to the present invention, the acylation may be performed not only on the outermost surface of the cellulose nanofiber but also on the inner region near the surface.

  In the acylation treatment, the substitution degree of the hydroxyl group with the acyl group is preferably in the range of 0 to 2.5. In the present application, the “acyl group substitution degree” is a value calculated according to ASTM D817.

  As a method for adjusting the substitution degree with an acyl group, a conventionally known acylation method can be employed.

  In the present invention, the functional group introduced into the hydroxyl group (hydroxyl group) of the nanofiber by chemical modification includes acetyl group, methacryloyl group, propanoyl group, butanoyl group, iso-butanoyl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group Group, nonanoyl group, decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, 2-methacryloyloxyethylisocyanoyl group and the like, and the hydroxyl group (hydroxyl group) of cellulose fiber includes One kind of these functional groups may be introduced, or two or more kinds may be introduced.

  Of these, acetyl group, methacryloyl group and the like are preferable.

<Acylation treatment by vapor phase surface treatment method>
As the acylation treatment by the vapor phase surface treatment method according to the present invention, various conventionally known methods can be employed. In the presence of an acid catalyst, acylating agents such as acyl halides, carboxylic acid anhydrides, and carboxylic acids can be used. A method of acylating by exposing cellulose nanofibers to steam is preferred.

Specifically, for example, as a pretreatment, after cellulose nanofibers are subjected to ZnCl ₂ / acetic acid treatment, acetylation can be performed by enclosing acetic anhydride in a heated acetic anhydride vapor atmosphere.

<Acylation by supercritical surface treatment>
In the present application, “acylation treatment by supercritical region surface treatment” refers to a treatment method in which cellulose nanofibers are dissolved in a solvent at a temperature and pressure belonging to the supercritical region or subcritical region, and acylated.

  Here, the “supercritical region” refers to a temperature / pressure region that gives a supercritical fluid in a phase diagram (phase diagram) showing the transition of a gas-liquid solid state. Further, the “supercritical fluid” refers to a fluid that is in a state that is higher than the critical temperature and higher than the critical pressure. A supercritical fluid can be understood as a high-density fluid having high kinetic energy, and exhibits a liquid behavior in terms of dissolving a solute and a gas characteristic in terms of density variability. Although there are various solvent properties of supercritical fluids, it is important that they are low-viscosity, highly diffusive, and have excellent permeability to solid materials (see: Supercritical Fluid Science and Technology, supervised by Shozaburo Saito). (1996, Sankyo Business).

A high-density region in a temperature range slightly lower than the critical temperature is generally called a subcritical region. In the present application, the subcritical region has a temperature equal to or higher than the boiling point of the solvent and a pressure of 10 kgf / cm ² ( 1.013 MPa) or more.

  The organic solvent used in the present invention is not particularly limited, but contains carbon dioxide and ketones having 12 or less carbon atoms, and esters and the like are used as a combined solvent. These esters and ketones may have a cyclic structure or may have two or more types of functional groups.

  Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone and the like. Of these, acetone, cyclopentanone, and cyclohexanone are particularly preferable.

  Examples of esters include methyl formate, ethyl formate, propyl formate, methyl acetate, and ethyl acetate.

In the present invention, it is particularly preferable to use carbon dioxide. Carbon dioxide has a critical temperature of 31.1 ° C. and a critical pressure of 75.3 kgf / cm ² (7.38 MPa), which is relatively easy to handle. This is preferable because a high-purity fluid is inexpensive and easily available. The suitable pressure of carbon dioxide in the supercritical state (including subcritical state) used in the acylation method according to the present invention is 80 to 500 kgf / cm ² (7.8 to 49 MPa), preferably 90 to 400 kgf. / Cm ² (8.8 to 39 MPa), more preferably 100 to 200 kgf / cm ² (9.8 to 19.6 MPa). Moreover, as temperature of the carbon dioxide gas of a suitable critical state, it is 32-200 degreeC, Preferably it is 35-100 degreeC, More preferably, it is 40-80 degreeC. Within these ranges, a supercritical state (including a subcritical state) is preferably obtained by appropriately selecting and combining the temperature and pressure.

  In the present invention, the acylation treatment by the supercritical region surface treatment method is specifically performed as follows.

  Liquid carbon dioxide is added to the pressure vessel to bring it to the supercritical or subcritical state under the preferred pressure and temperature described above. Dissolve the cellulose nanofiber and acylating agent according to the present invention in supercritical (or subcritical) carbon dioxide, or add liquid carbon dioxide to a pressure vessel to which these compounds have been added in advance, and then adjust the temperature and pressure. It may be adjusted to a supercritical state and dissolved.

  In that case, you may use together 1 type, or 2 or more types of lower alcohol, glycol, glycol ether, etc. as a dissolution aid.

<Stretching of cellulose nanofiber>
The cellulose nanofiber according to the present invention is preferably heated by infrared rays after being subjected to an acylation treatment and stretched by 100 times or more.

  As a method for stretching cellulose nanofibers, various conventionally known methods can be adopted. However, as a preferable method, at least a step in which cellulose nanofibers are sent out by a sending means, and a plurality of cellulose nanofibers that have been sent out are provided at a plurality of locations. It is preferable that it is a method of the aspect which has a process heated with the infrared rays light beam from.

  In the cellulose nanofiber stretching method, the cellulose nanofibers are stretched with respect to the raw cellulose nanofibers fed from the feeding means. As the delivery means, various types can be used as long as the filament can be delivered at a constant delivery speed such as a combination of a nip roller and several stages of driving rollers.

  In the stretching according to the present invention, it is preferable to provide a guide for regulating the position of the raw cellulose nanofiber immediately before the infrared heating. Heating by infrared light beam is characterized by heating in a very narrow range, and since the stretching tension is small at the start of stretching, the stretched part is likely to shake, so a guide device is provided to regulate the position of the cellulose nanofiber. . The guide can be a combination of thin tubes, grooves, combs, and thin bars.

  The raw cellulose nanofiber according to the present invention is heated to an appropriate stretching temperature by an infrared light beam irradiated by an infrared heating means (including a laser).

  This method enables stretching with a high degree of molecular orientation by abrupt stretching in a narrow region, and can reduce stretching breakage even with ultrahigh magnification stretching.

  For infrared heating, laser heating is particularly preferred. Among these, a carbon dioxide laser with a wavelength of 10.6 μm and a YAG (yttrium, aluminum, garnet) laser with a wavelength of 1.06 μm are particularly preferable. Lasers can narrow the radiation range to a small size, and are concentrated on a specific wavelength, so there is little wasted energy.

The carbon dioxide laser has a power density of 10 W / cm ² or more, preferably 20 W / cm ² or more, and most preferably 30 W / cm ² or more. This is because the high magnification stretching of the present invention can be achieved by concentrating high power density energy in a narrow stretching region. In addition, the power density at the time of irradiating on a filament from several places shows each power density in total.

  In this case, the infrared light beam is preferably irradiated from a plurality of locations. This is because heating from only one side of the cellulose nanofiber is difficult to stretch due to asymmetric heating when the melting temperature of the cellulose nanofiber is high or when uniform heating for obtaining good physical properties is required. In addition, it is preferable that irradiation from several places is irradiation from a symmetrical direction with respect to the running axis of a cellulose nanofiber. This is because it is necessary to thoroughly perform symmetrical heating in order to obtain cellulose nanofibers with high magnification and high physical properties. Such irradiation from a plurality of locations may be performed from a plurality of infrared light flux light sources, but a plurality of times along the path of the raw cellulose nanofiber by reflecting the light flux from one light source by a mirror. It can also be achieved by irradiating with. As the mirror, not only a fixed type but also a rotating type such as a polygon mirror can be used.

  Further, as another means for irradiation from a plurality of locations, there is a means for irradiating the raw cellulose nanofibers with a light source from a plurality of light sources from a plurality of locations. A high-power light source can be obtained by using a plurality of sets of stable and inexpensive laser oscillators with a relatively small laser light source.

  According to this method, the stretching ratio of the cellulose nanofiber can be 10 times or more, preferably 100 times or more.

  Examples of embodiments of the stretching method will be described below with reference to the drawings.

  FIG. 1 shows an example of a schematic process of a method for stretching cellulose nanofibers. The raw cellulose nanofiber 1 is fed out from the state wound on the reel 11, and is fed out from the feeding nip rollers 13 a and 13 b through the comb 12 at a constant speed. Further, the reels 11 may be fed out from a plurality of reels 11, combined with a comb 12, and sent to the next process. The delivered raw cellulose nanofiber 1 is regulated in position by the guide 15 and descends at a constant speed. The guide 15 accurately determines the irradiation position of the laser and the traveling position of the filament. In the drawing, an injection needle is used, but a thin pipe, a comb, a snail wire, or the like can also be used. The laser beam 6 is irradiated from the laser oscillation device 5 to the heating cellulose M having a certain width from the laser oscillation device 5 directly below the guide tool 15.

  FIG. 2 shows an example of means for irradiating the raw cellulose nanofiber with the infrared light flux employed in the present invention from a plurality of locations. FIG. A is a plan view and FIG. B is a side view. The infrared light beam 21 a irradiated from the infrared irradiator passes through the region P (inside the dotted line in the figure) through which the raw cellulose nanofiber 1 passes, reaches the mirror 22, becomes the infrared light beam 21 b reflected by the mirror 22, and is reflected by the mirror 23. The infrared light beam 21c is reflected. The infrared light beam 21c passes through the region P and irradiates the raw cellulose nanofibers 120 degrees after the irradiation position of the first raw filament. The infrared light beam 21c having passed through the region P is reflected by the mirror 24 to become an infrared light beam 21d, and reflected by the mirror 25 to become an infrared light beam 21e. The infrared light beam 21e passes through the region P and irradiates the raw cellulose nanofiber 1 after 120 degrees opposite to the infrared light beam 21c at the irradiation position of the first raw cellulose nanofiber. Thus, the raw cellulose nanofiber 1 can be heated uniformly from a symmetrical position by 120 degrees by the three infrared light beams 21a, 21c, and 21e. As described above, it is important that the raw cellulose nanofiber 1 can be irradiated with the infrared light beam 21 from a symmetrical position. In the case of asymmetry, it is difficult to obtain cellulose nanofiber having good physical properties without uniform heating. is there.

(resin)
As the resin according to the present invention, a thermoplastic resin, a solvent-soluble resin, or a curable resin can be preferably used. When a thermoplastic resin is used, the composition of the present invention is easily molded. In addition, when a thermoplastic resin or a curable resin is used, the optical anisotropy of the composition of the present invention is reduced.

  Examples of the thermoplastic resin include polyethylene, polypropylene, ABS resin, PMMA (polymethyl methacrylate), polystyrene, polycarbonate, polycycloolefin (Nippon ZEON Corporation, JSR Corporation Arton, Polyplastics Corporation TOPAS, Mitsui Chemicals, Inc.) ), Polylactic acid, cellulose acetate propionate, cellulose acetate butyrate, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyphenylene oxide, polycaprolactone, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polypropylene Terephthalate, polybutylene succinate, poly-3-hydroxybutyrate, polyarylate, Niro , Aramid, thermoplastic elastomers, silicones, and the like.

  Examples of the thermosetting resin include acrylic resin, methacrylic resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, silicone resin, diallyl phthalate resin, furan resin, bismaleimide resin, cyanate resin, and the like. .

  As the solvent-soluble resin, a resin that is soluble in water or an organic solvent can be used. Examples of the organic solvent for dissolving the solvent-soluble resin include methanol, ethanol, isopropanol, butanol, methylene chloride, chloroform, DMF (N, N-dimethylformamide), DMAc (N, N-dimethylacetamide), NMP (N-methylpyrrolidone). ), Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 1,4-dioxane, THF, ethyl acetate, methyl acetate, acetonitrile, glycerin, ethylene glycol, 1,1,1,3,3,3-hexafluoroisopropanol, toluene Xylene, anisole, n-hexane, cyclohexane, 1,2-dichloroethane, acetic acid, trifluoroacetic acid, pyridine, DMSO (dimethyl sulfoxide), nitromethane, nitrobenzene, etc. Al may be used singly or a plurality combination.

  As the resin used in the present invention, a cellulose acetate resin is particularly preferable.

<Method for preparing composition>
The composition according to the present invention is obtained by mixing cellulose nanofibers and a resin.

  For example, when the resin is a thermoplastic resin, it can be mixed with cellulose nanofibers in a state where the resin is melted by heating using a biaxial kneader or the like. The kneading temperature is preferably a temperature at which the melt viscosity of the thermoplastic resin is lowered and is not higher than the thermal decomposition temperature of the cellulose nanofiber.

  The kneading temperature is preferably 270 ° C. or lower, more preferably 260 ° C. or lower, and particularly preferably 250 ° C. or lower.

  When the resin is a solvent-soluble resin, the cellulose nanofibers can be mixed by dissolving the resin in the solvent. In the case of a solvent-soluble resin, there is an advantage that it can be mixed at a temperature sufficiently lower than the thermal decomposition temperature of cellulose nanofibers. As the solvent to be used, water, methanol, ethanol, isopropanol, butanol, methylene chloride, chloroform, DMF (N, N-dimethylformamide), DMAc (N, N-dimethylacetamide), NMP (N-methylpyrrolidone), acetone, Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 1,4-dioxane, THF, ethyl acetate, methyl acetate, acetonitrile, glycerin, ethylene glycol, 1,1,1,3,3,3-hexafluoroisopropanol, toluene, xylene, anisole N-hexane, cyclohexane, 1,2-dichloroethane, acetic acid, trifluoroacetic acid, pyridine, DMSO (dimethyl sulfoxide), nitromethane, nitrobenzene and the like. You may use as a mixed solvent which mixed multiple these solvents.

  When the resin is a curable resin, it can be mixed by adding cellulose nanofibers to the liquid monomer and / or prepolymer. At this time, a solvent may be appropriately used. As the solvent, those shown above can be used.

  The mixing mass ratio of the resin and the cellulose nanofiber in the composition of the present invention is usually 1: 0.01 to 3, preferably 1: 0.01 to 2, and more preferably 1: 0.02. It is -2, More preferably, it is 1: 0.03-1. If the ratio of cellulose nanofiber is too small, the effects of lowering the thermal expansion coefficient and improving the elastic modulus tend to be hardly observed, and if the ratio of cellulose nanofiber is too large, molding tends to be difficult.

  Components other than cellulose nanofiber and resin may be contained in the composition of the present invention. Examples of such components include heat stabilizers, plasticizers, UV absorbers, colorants, rubbers, elastomers, and the like. The addition amount of these components is preferably 0.0001 to 20% by mass of the composition, more preferably 0.0001 to 10% by mass, and further preferably 0.0001 to 5% by mass. preferable.

  Hereinafter, a resin that can be suitably used as a matrix resin in the present invention will be described in detail.

<Cellulose ester resin>
Examples of the cellulose ester used in the present invention include cellulose acetate, cellulose propionate, cellulose butyrate and the like, JP-A Nos. 10-45804, 08-231761, and US Pat. No. 2,319,052. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in the literature can be used. Particularly preferred are cellulose triacetate and cellulose acetate propionate. These cellulose esters can be used alone or in combination. The molecular weight is preferably 70000-200000 in terms of number average molecular weight (Mn), more preferably 100000-200000.

  In the case of cellulose triacetate, those having an average degree of acetylation (bound acetic acid amount) of 54.0 to 62.5% are preferably used, and more preferably an average degree of acetylation of 58.0 to 62.5%. Cellulose triacetate.

  Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, the following formula ( It is a cellulose ester containing the cellulose ester which satisfy | fills I) and (II) simultaneously.

Formula (I) 2.0 ≦ X + Y ≦ 2.6
Formula (II) 0.1 ≦ Y ≦ 1.2
Furthermore, a cellulose acetate propionate (total acyl group substitution degree = X + Y) resin of 2.4 ≦ X + Y ≦ 2.6 and 1.4 ≦ X ≦ 2.3 is preferable. Among them, 2.4 ≦ X + Y ≦ 2.6, 1.7 ≦ X ≦ 2.3, 0.1 ≦ Y ≦ 0.9, cellulose acetate propionate resin, cellulose acetate butyrate (total acyl group substitution degree = X + Y ) Resins are preferred. The portion not substituted with an acyl group usually exists as a hydroxyl group. These cellulose ester resins can be synthesized by a known method. The measuring method of the substitution degree of an acyl group can be measured according to the rule of ASTM-D817-96.

  As the cellulose ester, a cellulose ester synthesized using cotton linter, wood pulp, kenaf or the like as a raw material can be used alone or in combination. In particular, it is preferable to use a cellulose ester synthesized from cotton linter alone or in combination.

  The base material of the resin composite according to the present invention is preferably flexible. Here, “flexibility” is assumed to have at least 100 times of bending resistance in the MIT test described in JIS P 8115: 2001.

  The expansion coefficient of the thermoplastic resin alone is preferably 0 to 120 ppm / ° C. More preferably, it is 5-100 ppm / ° C, and most preferably 10-80 ppm / ° C.

<acrylic resin>
In the present invention, it is also preferable to use an acrylic resin. The acrylic resin used in the present invention can be produced by the method described in JP-A-2003-12859.

<Cyclic olefin resin>
In the present invention, it is also preferable to use a cyclic olefin resin. Examples of the cyclic olefin resin include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

(Plasticizer)
The resin composite of the present invention preferably contains a plasticizer. Examples of the plasticizer include a phosphate ester plasticizer, a phthalate ester plasticizer, a trimellitic ester plasticizer, and a pyromellitic acid. A plasticizer, a glycolate plasticizer, a citrate ester plasticizer, a polyester plasticizer, a polyhydric alcohol ester plasticizer, or the like can be preferably used.

  The amount of these plasticizers used is preferably from 1 to 20% by mass, particularly preferably from 3 to 13% by mass, based on the cellulose ester, in terms of film performance, processability and the like.

(UV absorber)
It is preferable to add an ultraviolet absorber to the resin composite of the present invention.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties.

  Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, and the like. For example, but not limited to.

  As the ultraviolet absorber preferably used in the present invention, a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber, which are highly transparent and excellent in preventing the deterioration of the polarizing plate and the liquid crystal, are preferable, and unnecessary coloring occurs. Less benzotriazole-based UV absorbers are particularly preferably used.

(Method for producing resin composite)
As the method for producing the resin composite of the present invention, the usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method and the like can be used. From the viewpoints of suppressing foreign matter defects and optical defects such as die lines, a solution casting method by a casting method and a melt casting method are preferable.

  Hereinafter, as a typical example, a production method for producing the resin composite of the present invention will be described in detail.

<Method for producing resin composite by solution casting method>
(Organic solvent)
When the resin composite of the present invention is produced by a solution casting method, an organic solvent useful for forming a dope can be used without limitation as long as it dissolves a thermoplastic resin such as a cellulose ester resin.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, ethyl lactate, lactic acid , Diacetone alcohol and the like, methylene chloride, methyl acetate, ethyl acetate, acetone, ethyl lactate and the like are preferably used. That.

  In addition to the organic solvent, the dope may contain 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, facilitating peeling from the metal support, and when the proportion of alcohol is small, the dissolution of the thermoplastic resin in a non-chlorine organic solvent system is promoted. There is also a role.

  In particular, the thermoplastic resin should be a dope composition in which at least a total of 10 to 45 mass% is dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. preferable.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

  Hereinafter, a preferred method for forming a film-like resin composite (hereinafter also simply referred to as “film”) according to the present invention will be described.

1) Dissolution Step In this step, a thermoplastic resin, a heat-shrinkable material, and other additives are dissolved in an organic solvent mainly composed of a good solvent for the thermoplastic resin while stirring to form a dope.

  For the dissolution of the thermoplastic resin, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 Alternatively, various dissolution methods such as a cooling dissolution method as described in JP-A-9-95538 and a high-pressure method as described in JP-A-11-21379 can be used. The method of pressurizing at a boiling point or higher is preferred.

  Recycled material is a finely pulverized film, which is generated when the film is formed, cut off on both sides of the film, or the original film that has been speculated out due to scratches, etc. Reused.

2) Casting process An endless metal belt, such as a stainless steel belt or a rotating metal drum, which supports the dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and supported infinitely. This is a step of casting a dope from a pressure die slit to a casting position on the body.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

3) Solvent evaporation step The web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. High efficiency and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.

  The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

  In addition, it is preferable that the residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. If the web is peeled off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be lost, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

  The residual solvent amount of the web is defined by the following formula.

Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, when wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension that can be peeled to 166.6 N / m, and then peel at a minimum tension to 137.2 N / m, and particularly preferably peel at a minimum tension to 100 N / m.

  In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

5) Drying and stretching step After peeling, using a drying device that alternately passes the web through rolls arranged in the drying device and / or a tenter stretching device that clips and transports both ends of the web with clips. Dry the web.

  Generally, the drying means blows hot air on both sides of the web, but there is also a means for heating by applying microwaves instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout the drying is generally carried out at 40-250 ° C. It is particularly preferable to dry at 40 to 160 ° C.

  When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.

  It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

  In addition, extending | stretching operation may be divided | segmented and implemented in multiple steps, and it is also preferable to implement biaxial stretching in a casting direction and a width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.

  In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of x1.01 to x1.5 times in both the width direction and the longitudinal direction.

  When the tenter is used, the residual solvent amount of the web is preferably 20 to 100% by mass at the start of the tenter, and it is preferable to perform drying while applying the tenter until the residual solvent amount of the web becomes 10% by mass or less. More preferably, it is 5% by mass or less.

  30-160 degreeC is preferable, as for the drying temperature in the case of performing a tenter, 50-150 degreeC is more preferable, and 70-140 degreeC is the most preferable.

  In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable.

6) Winding step This is a step of winding the film as a film by a winder after the amount of residual solvent in the web is 2% by mass or less. By reducing the amount of residual solvent to 0.4% by mass or less, dimensional stability can be improved. A good film can be obtained. It is particularly preferable to wind up at 0.00 to 0.10% by mass.

  As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  The film according to the present invention is preferably a long film. Specifically, the film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a film is 1.3-4m, and it is more preferable that it is 1.4-2m.

  Although there is no restriction | limiting in particular in the film thickness of the film concerning this invention, It is preferable that it is 20-200 micrometers, It is more preferable that it is 25-150 micrometers, It is especially preferable that it is 30-120 micrometers.

<Method for producing resin composite by melt casting film forming method>
The method in the case of manufacturing the resin composite of this invention as a film-form resin film by the melt casting film forming method is demonstrated.

<Melted pellet manufacturing process>
The composition constituting a film made of a thermoplastic resin and a heat shrinkable material used for melt extrusion is usually preferably kneaded in advance and pelletized.

  The pelletization may be performed by a known method. For example, an additive comprising a dried thermoplastic resin and a heat-shrinkable material is supplied to an extruder with a feeder and kneaded using a single-screw or twin-screw extruder. It is possible to extrude into a strand, cool with water or air, and cut.

  It is important to dry the raw material before extruding to prevent decomposition of the raw material. In particular, since the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air dryer or a vacuum dryer to keep the moisture content at 200 ppm or less, and further 100 ppm or less.

  Additives may be fed into the extruder and fed into the extruder, or may be fed by individual feeders. In order to mix a small amount of additives such as an antioxidant uniformly, it is preferable to mix them in advance.

  The antioxidant may be mixed with each other, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with a thermoplastic resin and mixed, or mixed by spraying. May be.

A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Further, if the contact with air, such as the exit from the feeder unit or die, it is preferable that the atmosphere such as dehumidified air and dehumidified N ₂ gas.

  The extruder is preferably processed at as low a temperature as possible so that the shearing force is suppressed and the resin can be pelletized so as not to deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

<Process for extruding molten mixture from die to cooling roll>
First, using a single-screw or twin-screw type extruder, the melt temperature Tm when extruding the pellet is about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matters, The film is coextruded into a film, solidified on a cooling roll, and cast while pressing with an elastic touch roll.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.

  When foreign matter such as scratches or plasticizer aggregates adheres to the die, streak-like defects may occur. Such a defect is also called a die line, but in order to reduce surface defects such as the die line, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.

  The inner surface that contacts the molten resin such as an extruder or a die is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material having a low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

  In the present invention, there is no particular limitation on the cooling roll, but it is a roll having a structure in which a heat medium or a coolant that can be controlled in temperature flows with a highly rigid metal roll, and the size is not limited. It is sufficient that the film is large enough to cool the film, and the diameter of the cooling roll is usually about 100 mm to 1 m.

  Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the hardness of the surface or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  The surface roughness of the chill roll surface is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable that the surface processed is further polished to have the above-described surface roughness.

  In the present invention, examples of the elastic touch roll include JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97-028950, JP-A-11-235747, A silicon rubber roll coated with a thin film metal sleeve can be used as described in Japanese Unexamined Patent Application Publication No. 2002-36332, Japanese Patent Application Laid-Open No. 2005-172940 and Japanese Patent Application Laid-Open No. 2005-280217.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

<Extension process>
In the present invention, the film obtained as described above can be further stretched 1.01 to 3.0 times in at least one direction after passing through the step of contacting the cooling roll.

  Preferably, the film is stretched 1.1 to 2.0 times in both the longitudinal (film transport direction) and lateral (width direction) directions.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. In particular, when the optical film also serves as a polarizing plate protective film, it is preferable to stack the polarizing film in a roll form by setting the stretching direction to the width direction.

  By stretching in the width direction, the slow axis of the optical film becomes the width direction.

  Usually, the draw ratio is 1.1 to 3.0 times, preferably 1.2 to 1.5 times, and the draw temperature is usually Tg to Tg + 50 ° C. of the resin constituting the film, preferably Tg to Tg + 50 ° C. In the temperature range.

  The stretching is preferably performed under a uniform temperature distribution controlled in the longitudinal direction or the width direction. The temperature is preferably within ± 2 ° C, more preferably within ± 1 ° C, and particularly preferably within ± 0.5 ° C.

  When the film-shaped resin film produced by the above method is used as an optical film, the film may be contracted in the longitudinal direction or the width direction for the purpose of adjusting the retardation of the optical film and reducing the dimensional change rate.

  In order to shrink in the longitudinal direction, for example, there is a method in which the film is shrunk by temporarily clipping out the width stretching and relaxing in the longitudinal direction, or by gradually narrowing the interval between adjacent clips of the transverse stretching machine.

  The uniformity in the slow axis direction is also important, and the angle is preferably −5 to + 5 ° with respect to the film width direction, more preferably in the range of −1 to + 1 °, and particularly −0. It is preferably in the range of 5 to + 0.5 °, particularly preferably in the range of −0.1 to + 0.1 °. These variations can be achieved by optimizing the stretching conditions.

  The film-like resin film of the present invention is preferably a long film. Specifically, the film-like resin film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a film is 1.3-4m, and it is more preferable that it is 1.4-2m.

  There is no restriction | limiting in particular in the film thickness of the film-form resin film which concerns on this invention, It is preferable to change according to the objective. For example, when using for a polarizing plate protective film, it is preferable that it is 20-200 micrometers, It is more preferable that it is 25-150 micrometers, It is especially preferable that it is 30-120 micrometers.

<Production equipment for resin composites>
FIG. 3 is a schematic flow sheet showing an overall configuration of an example of an apparatus for producing a film-like resin composite according to the present invention. In FIG. 3, the resin film is produced by mixing a film material such as a thermoplastic resin, and then melt-extruding the first cooling roll 5A from the casting die 4A onto the first cooling roll 5A using the extruder 1A. In addition, the film 10A is further circumscribed with a total of three cooling rolls, that is, the second cooling roll 7A and the third cooling roll 8A, and is cooled and solidified to form the film 10A. Next, after the film 10A peeled off by the peeling roll 9A is stretched in the width direction by holding both ends of the film by the stretching device 12A, it is wound up by the winding device 16A. In addition, a touch roll 6A is provided to clamp the molten film on the surface of the first cooling roll 5A in order to correct the flatness. The touch roll 6A has an elastic surface and forms a nip with the first cooling roll 5A.

  In the present invention, it is preferable to add a device for automatically cleaning the belt and the roll to the manufacturing apparatus. There are no particular restrictions on the cleaning device. For example, there are a method of niping a brush roll, a water absorbing roll, an adhesive roll, a wiping roll, an air blow method of blowing clean air, a laser incinerator, or a combination thereof. is there.

  In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Example of the present invention)
(Preparation of cellulose nanofiber 1)
Microfibrillated cellulose (abbreviated as “MFC”): Microfibrillated softwood kraft pulp (NBKP) by high-pressure homogenizer treatment, average fiber diameter of 1 μm) is sufficiently stirred in water and 1% strength by weight Prepare 7 kg of turbid liquid, and use a grinder ("Pure Fine Mill KMG1-10" manufactured by Kurita Kikai Seisakusho Co., Ltd.) to remove this water suspension from the center of the disk rotating at 1200 rpm in the almost contacted state. The operation of passing toward the surface was performed 10 times (10 pass).

The dispersion was treated with ZnCl ₂ , freeze-dried, taken out, and then subjected to surface treatment acetylation treatment by applying acetic anhydride vapor heated at 50 ° C. The I _β type crystallinity was 58%.

  A part of this dispersion was taken out and the methylene chloride was evaporated, and then 100 cellulose nanofibers were observed with an electron microscope. The average fiber diameter was 200 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.10.

(Preparation of cellulose nanofiber 2)
To a fiber obtained by treating a sulfite bleached softwood pulp equivalent to 5 g in dry mass with a high-pressure homogenizer, 0.063 g of TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl (2,2,6,6-tetramethylpiperidine1) -Oxyl)) and 0.63 g of sodium bromide in 375 ml of water, then 13% by weight aqueous sodium hypochlorite solution of 2.5 mmol sodium hypochlorite with respect to 1 g of pulp. Then, hypochlorous acid was added to start the reaction. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10.5. When no change in pH was observed, the reaction was considered to be completed, and the reaction product was filtered, then washed with sufficient water and filtered to obtain a reaction product fiber. This was subjected to ZnCl ₂ treatment, freeze-dried and then taken out, and then subjected to surface treatment by applying vapor of propionic anhydride by a similar method such as adjustment of cellulose nanofiber 1.

The I _β type crystallinity was 53%. Moreover, the average fiber diameter was 30 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.05.

(Preparation of cellulose nanofiber 3)
After pre-treatment of the high-pressure homogenizer-treated fiber of sulfite bleached softwood pulp equivalent to 5 g in dry mass with ZnCl ₂ , esterification is carried out in the presence of butanoic anhydride under supercritical CO ₂ (10 MPa, 70 ° C.). went.

The surface-treated fiber was stretched using the apparatus of FIG. The laser was manufactured by Onizuka Glass Co., Ltd., and a carbon dioxide laser oscillator stretching ratio of 10 W at maximum was used. At this time, the beam diameter was 4 mm, and the power density was 23.7 W / cm ² . In this state, a fiber was prepared by stretching the original fiber by setting the draw ratio to 100 times.

The I _β type crystallinity was 50%. The average fiber diameter was 350 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.08.

(Preparation of cellulose nanofiber 4)
A fiber was prepared in the same manner as in the cellulose nanofiber 3 except that it was changed to isobutyric anhydride in the same manner. The I _β type crystallinity was 48%. The average fiber system was 300 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.06.

(Preparation of cellulose nanofiber 5)
Cellulose nanofibers were produced in the same manner as cellulose nanofibers 2 and were produced in the same manner as cellulose nanofibers 3 except that butanoic anhydride was changed to acetic anhydride in the surface treatment.

The I _β type crystallinity was 45%. The average fiber system was 80 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.09.

<Preparation of resin film 1>
Next, using the produced cellulose nanofiber 1, a crystalline cellulose-containing film 1 having a film thickness of 100 μm and a winding number of 5000 m was produced using the following dope solution.

(Preparation of dope solution)
Triacetyl cellulose 100 parts by weight Methylene chloride solution containing 8 parts by weight of ethanol 840 parts by weight 25 parts by weight as MFC solids <Preparation of resin films 2-5>
Using the matrix material shown in Table 1, various crystalline cellulose-containing films were prepared in the same manner as described above.

(Comparative example)
<Preparation of cellulose nanofiber 1 for comparison>
A cellulose nanofiber 2 that was not surface-treated was used. The I _β type crystallinity was 60%. The average fiber system was significantly aggregated and could not be measured by SEM.

<Preparation of cellulose nanofiber 2 for comparison>
Copper ammonia cellulose solution (cellulose: 10% by mass, copper: 3.6% by mass, ammonia: 6.1% by mass, others are almost water), ammonia water (28% by mass), polyethylene glycol (hereinafter “PEG”) (Abbreviated.) Aqueous solution (10% by mass, molecular weight listed in Table 1) and surfactant (trade name: Pegnol (manufactured by Toho Chemical Co., Ltd.)) were added so as to have the composition shown in Table 1, and kneaded well Thus, a spinning dope for electrostatic spinning was prepared.

  This spinning stock solution is put into a syringe, and is quantitatively discharged (2.62 ml / hr) onto a metal substrate from a metal nozzle having an inner diameter of 0.41 mm. Between the metal nozzle and the metal substrate (distance: 10 cm), a high-voltage power source is 20 kV. A voltage was applied to perform electrospinning. The crystal system was type III.

<Preparation of cellulose nanofiber 3 for comparison>
It was produced in the same manner as the cellulose nanofiber 5 except that the material was bacterial cellulose. The crystallinity was 45% and it was an I _α type structure. The average fiber system was 250 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.17.

<Preparation of cellulose nanofiber 4 for comparison>
It was produced by the same method as cellulose nanofiber 5. The I _β type crystallinity was 38%. The average fiber system was 250 nm, and the variation coefficient (S / Da) of the fiber diameter was 0.30.

<Production of Comparative Resin Films 1 to 4>
Using the matrix material (resin) in Table 1, various comparative cellulose nanofiber-containing films were prepared in the same manner as described above.

<Evaluation>
Resin films 1 to 5 using each of cellulose nanofibers 1 to 5 are examples 1 to 5 according to the present invention, and comparative resin films 1 to 4 using each of comparative cellulose nanofibers 1 to 4 are compared. The following evaluation was performed as Examples 1-4.

(Average linear expansion coefficient)
Using an EXSTAR TMA / SS6000 type thermal stress strain measuring device manufactured by Seiko Electronics Co., Ltd., the temperature was raised from 30 ° C. to 50 ° C. at a rate of 5 ° C. for 1 minute in a nitrogen atmosphere, and once held, again The temperature was raised at a rate of 5 ° C. per minute, and the value at 30 to 150 ° C. was measured and determined. The load was 5 g and the measurement was performed in the tensile mode.

  Using an EXSTAR TMA / SS6000 type thermal stress strain measuring device manufactured by Seiko Electronics Co., Ltd., the temperature was raised from 30 ° C. to 50 ° C. at a rate of 5 ° C. for 1 minute in a nitrogen atmosphere, and once held, again The temperature was raised at a rate of 5 ° C. per minute, and the value at 30 to 150 ° C. was measured and determined. The load was set to 5 g, and measurement was performed in a tensile mode for evaluation. In addition, CTE (Coefficient of thermal expansion) of Table 1 is a linear expansion coefficient computed by the said measurement.

(Nanofiber cellulose crystallinity)
The cellulose crystallinity of the nanofiber was defined as the ratio of the crystal scattering peak area on the X-ray diffraction diagram obtained by X-ray diffraction measurement. The manufactured nanofiber sheet is attached to the sample holder, and the background scattering is removed from the X-ray diffraction pattern obtained by measuring the diffraction angle of X-ray diffraction from 10 ° to 32 °. The area obtained by connecting 10 °, 18.5 °, and 32 ° on the diffraction curve with a straight line is an amorphous portion, and the other area is a crystalline portion.

  The cellulose crystallinity of the nanofiber was calculated by the following formula as a ratio of the crystal part to the entire area of the diffraction pattern.

Crystallinity = (Area of crystal part) / (Area of entire X-ray diffraction diagram) × 100 (%)
(Fiber diameter distribution)
Evaluation was made by a coefficient of variation (also referred to as “CV value”) which is a ratio (S / Da) of the average fiber diameter Da and its standard deviation S. In addition, the fiber diameter was observed about 100 points with the scanning electron microscope (SEM) photograph, the fiber diameter was calculated | required, and the variation coefficient (distribution) was computed.

(transparency)
Using a spectrophotometer U-3200 (manufactured by Hitachi, Ltd.), each sample was measured for spectral transmittance at 380 nm, 550 nm, and 650 nm, and the average value of transmittance at each wavelength was measured in the visible light range. Transparency was evaluated by using transmittance.

(Haze)
The haze (Hf) of the resin film was measured according to JIS-K7136 using a haze meter (NDH2000; manufactured by Nippon Denshoku Industries Co., Ltd.).

  The above evaluation results are summarized in Table 1.

  As is clear from the results shown in Table 1, it can be seen that the sample (resin film) according to the present invention is superior in linear expansion coefficient, transparency, and haze to the comparative example.

  That is, it can be seen that the present invention can provide a resin film having high transparency and a low linear expansion coefficient and excellent in dimensional stability such as thermal expansion and thermal shrinkage and a method for producing the same.

DESCRIPTION OF SYMBOLS 1 Original cellulose nanofiber 5 Laser oscillator apparatus 6 Laser beam 11 Reel 12 Comb 13a, 13b Feeding nip roll 15 Guide tool 16a, 16b Taking-out nip roll 17 Stretched cellulose nanofiber 18 Birefringence measuring apparatus 19 Take-up reel,
21a, 21b, 21c, 21d, 21e Infrared luminous flux,
22, 23, 24, 25 Mirror P region 1A Extruder 2A Filter 3A Static mixer 4A Casting die 5A Rotating support (first cooling roll)
6A sandwiching rotary body (touch roll)
7A Rotating support (second cooling roll)
8A Rotating support (third cooling roll)
9A Peeling roll 10A Film 11A, 13A, 14A Transport roll 12A Stretching machine 15A Slitter 16A Winding machine F Resin film

Claims (6)

A resin composite containing cellulose nanofibers, wherein the cellulose nanofibers are plant-derived cellulose fiber aggregates whose surfaces are subjected to acylation treatment, and the I _β type crystallinity is 40 to 60%. The average fiber diameter is in the range of 4 to 200 nm, and the coefficient of variation (S / Da), which is the ratio of the average fiber diameter Da and its standard deviation S, is within 0.15. Characteristic resin composite.   It is a manufacturing method of the resin composite which manufactures the resin composite_body | complex of Claim 1, Comprising: The said acylation process is an acylation process by a gaseous-phase surface treatment method or a supercritical area | region surface treatment method, It is characterized by the above-mentioned. A method for producing a resin composite.   A method for producing cellulose nanofibers contained in the resin composite according to claim 1, wherein the freeze-dried cellulose nanofibers are acylated by a gas phase surface treatment method. Method.   A method for producing cellulose nanofibers contained in the resin composite according to claim 1, wherein the freeze-dried cellulose nanofibers are acylated by a supercritical region surface treatment method. Production method.   The method for producing cellulose nanofibers contained in the resin composite according to claim 1, wherein the cellulose nanofibers subjected to acylation treatment are heated with infrared rays and stretched 100 times or more. The manufacturing method of the cellulose nanofiber of 3 or Claim 4.   A method for producing cellulose nanofibers contained in a resin composite, wherein the cellulose nanofibers subjected to acylation treatment are heated with infrared rays and stretched 100 times or more.

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