JP2011094046A - Resin film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin film which has a high transparency and a low coefficient of linear expansion and is excellent in dimensional stability such as thermal expansion and thermal shrinkage; and to provide a method for manufacturing the resin film. <P>SOLUTION: The resin film is a resin film containing crystalline cellulose, a dispersing agent, and a matrix resin, wherein the substitution degree of a hydroxyl group of the crystalline cellulose by an acyl group ranges from 0 to 2.5, the average minor axis diameter of the crystalline cellulose is 2 μm or less, and the dispersing agent is non-compatible with the matrix resin, a thermoplastic resin has a molecular weight of 1,000 or more, and the matrix resin is a thermoplastic resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin film having high transparency, a low linear expansion coefficient and excellent dimensional stability, and a method for producing the same.

  In a flat panel display typified by a liquid crystal display, a glass substrate is used as a support substrate. In recent years, thinning, lightening, and freedom of shape have been demanded, and instead of a glass substrate, a light and flexible film substrate has been studied.

  Various functional layers are laminated on the film substrate depending on the application. At this time, since the film is exposed to heat, dimensional stability such as thermal expansion and contraction is an important characteristic.

  As a technique for reducing the linear expansion coefficient of a film, there is a technique for reducing the linear expansion coefficient by adding a fibrous material to a matrix resin. Among them, a technique for adding crystalline cellulose has attracted attention.

  In the technique disclosed in Patent Document 1, crystalline cellulose is included in a binder resin, but a monomer solution of the binder resin is impregnated and cured by a solvent replacement method and then mixed with the matrix resin. In this method, dispersibility is determined at the stage of solvent replacement, and dispersibility and transparency are low.

  In the technique disclosed in Patent Document 2, surface treatment or the like is performed, but the dispersion means is only US dispersion, and the mechanical crushing force is weak and there is a problem in dispersibility. In order to improve dispersibility with this dispersing means, surface treatment and surface adsorption amount must be enormous.

  However, surface treatment with a high degree of substitution causes a decrease in the crystallinity of cellulose, and the performance of the low linear expansion coefficient, which is the original purpose, is not improved. Moreover, in patent document 2, since a powder is once dried, bulk density becomes high and there exists a problem that it cannot add to a high density | concentration by the problem of a viscosity.

JP 2008-127540 A JP 2009-52016 A

  The present invention has been made in view of the above problems and situations, and its solution is 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 its production. Is to provide a way.

  The above-mentioned problem according to the present invention is solved by the following means.

  1. A resin film containing crystalline cellulose, a dispersant, and a matrix resin, wherein the degree of substitution of the hydroxyl group of the crystalline cellulose with an acyl group is in the range of 0 to 2.5, and the average of the crystalline cellulose A resin having a minor axis diameter of 2 μm or less, the dispersant being incompatible with the matrix resin, a molecular weight of 1000 or more, and the matrix resin being a thermoplastic resin the film.

  2. 2. The resin film as described in 1 above, wherein a difference in refractive index between the dispersant and the matrix resin is 0.2 or less.

  3. 3. The resin film as described in 1 or 2 above, wherein the degree of substitution is in the range of 0 to 2.0.

  4). 4. The resin film according to any one of 1 to 3, wherein the matrix resin contains 1% by mass or more of a cellulose ester resin.

  5. It is a manufacturing method of a resin film, Comprising: The resin film as described in any one of said 1 to said 4 is manufactured, The manufacturing method of the resin film characterized by the above-mentioned.

  By the above means of the present invention, it is possible to 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.

  In other words, by controlling the degree of substitution of the hydroxyl group of crystalline cellulose with an acyl group within a specified range, the degradation of crystallinity that causes performance degradation is suppressed, and re-aggregation is performed simultaneously with dispersion and disintegration in a solvent substitution state. It is possible to produce a highly transparent and low linear expansion coefficient optical film by adding a dispersing agent that prevents water and using a thermoplastic resin that has a molecular weight of 1000 or more and is incompatible with the matrix resin. It was.

Schematic flow sheet showing one embodiment of an apparatus for producing a film-like resin substrate

  The resin film of the present invention is a resin film containing crystalline cellulose, a dispersant, and a matrix resin, and the substitution degree of the hydroxyl group of the crystalline cellulose with an acyl group is within the range of 0 to 2.5. The crystalline cellulose has an average minor axis diameter of 2 μm or less, the dispersant is incompatible with the matrix resin, and has a molecular weight of 1000 or more, and the matrix resin is a thermoplastic resin. It is characterized by being. This feature is a technical feature common to the inventions according to claims 1 to 5.

  As an embodiment of the present invention, it is preferable that a difference in refractive index between the dispersant and the matrix resin is 0.2 or less from the viewpoint of manifesting the effect of the present invention. Moreover, it is preferable that the said substitution degree exists in the range of 0-1.5. Further, the matrix resin preferably contains 1% by mass or more of a cellulose ester resin.

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

  In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Crystalline cellulose)
The resin film of the present invention is characterized by containing crystalline cellulose and a dispersant. Here, “crystalline cellulose” is a raw material such as pulp, which has been purified by taking out a cellulose crystal region (part where cellulose molecular chains are densely and regularly present) by hydrolysis, and has a chemical structure of natural cellulose. The same thing as. In the present application, crystalline cellulose refers to those having a crystallinity of 30% or more as measured by an X-ray diffractometer. The crystal structure may be either α or β type.

  The crystalline cellulose can be obtained from those derived from plants such as wood, bamboo, kenaf and hemp, those produced by bacteria such as acetic acid bacteria, and those produced by marine organisms such as scallops.

  The crystalline cellulose used in the present invention has a minor axis diameter of 10 to 2000 nm (2 μm), more preferably 50 to 1500 nm, and further preferably 100 to 1000 nm (1 μm). By setting the minor axis diameter to 2000 nm or less, there is an advantage that mixing with the matrix is facilitated and the range of types of usable matrix is widened. The major axis diameter is preferably 10,000 nm (10 μm).

  The method for obtaining crystalline cellulose having a minor axis diameter of 10 to 2000 nm is not particularly limited. For example, it is obtained by using a method of hydrolyzing highly crystalline cellulose such as cellulose nanofiber, cellulose nanowhisker, bacterial cellulose, commercially available microcrystalline cellulose with mineral acid, or a method of disaggregating and dispersing with a high-pressure homogenizer. be able to.

  In the present invention, it is particularly preferable to use cellulose nanofibers as a raw material for crystalline cellulose. Here, “cellulose nanofiber” refers to a cellulose-based fiber having an average fiber diameter (short axis diameter) of 4 to 200 nm as a fiber. The “cellulosic fiber” refers to a microfibril of cellulose constituting a basic skeleton of a plant cell wall or the like, or a component fiber thereof, and is an aggregate of unit fibers having a fiber diameter (short axis diameter) of about 4 nm. In order to obtain high strength and low thermal expansion, it is preferable that this cellulose fiber contains a crystal structure of 40% or more.

  The fibers may be composed of single fibers that are sufficiently spaced and so as to enter each other. In this case, the average fiber diameter (short axis 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 (short axis diameter) is defined as the average value of the diameters of one yarn.

  The average fiber diameter (short axis diameter) of the fiber used in the present invention is preferably 4 to 1000 nm, more preferably 4 to 100 nm.

  In addition, if the average fiber diameter (short axis diameter) is in the range of 4 to 200 nm, fibers used in the present invention include fibers having a fiber diameter (short axis diameter) outside the range of 4 to 200 nm. However, the ratio is preferably 30% by mass or less, and desirably the fiber diameter (short axis diameter) of all the fibers is 200 nm or less, particularly 100 nm or less, particularly 60 nm or less.

  The length of the fiber is not particularly limited, but the average length is preferably 100 nm or more. If the average length of the fibers is shorter than 100 nm, the reinforcing effect is low, and the strength of the fiber-reinforced composite material may be insufficient. 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.

  The fiber diameter (short axis diameter) and fiber length can be measured with a commercially available microscope or 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 (short axis diameter) and fiber length (major axis diameter) 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. Although the pulverizing means is not limited, 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 performs grinding by shearing 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.

  The cellulose nanowhiskers can be described in the same manner as the cellulose nanofibers.

(Surface treatment for adjusting the degree of substitution)
The degree of substitution of the hydroxyl group with the acyl group of the crystalline cellulose according to the present invention is in the range of 0 to 2.5. Therefore, chemical modification by surface treatment is necessary to adjust the degree of substitution according to the chemical properties and purpose of crystalline cellulose.

  In the present application, the substitution degree of the acyl group 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.

  Among these, ester functional groups are particularly preferable, and acyl groups such as acetyl groups and / or methacryloyl groups are particularly preferable.

  In particular, by introducing a functional group that is the same or the same type as the functional group of the non-crystalline synthetic resin as the matrix material described later, the functional group of the crystalline cellulose and the functional group of the resin of the matrix material are covalently bonded, A favorable hygroscopicity reducing effect and transparency improving effect are obtained and preferable.

  The crystalline cellulose according to the present invention may be surface-modified with an organic group represented by the following general formula (1) as long as the effects of the present invention are not impaired. By combining organic groups, dispersibility in the matrix is improved, and aggregation is suppressed, so that there is a possibility of obtaining effects such as improvement of transparency and improvement of elastic modulus.

In General Formula (1), L ¹ is a linking group represented by any of the following General Formulas (2) to (21).

  Among these, from the viewpoint of easy formation of bonds, the general formulas (2), (3), (4), (6), (7), (8), (10), (11), (15) , (16), (17), (18), and (19) are preferred, and the linking group is preferably represented by formulas (2), (3), (4), (6), ( 7), (8), (15), (16), and (18) are more preferred, and the linking group is more preferably represented by the general formulas (2), (4), (6), (7 And a linking group represented by any one of (15).

  In the case of cellulose fiber, the group represented by the general formula (1) can be introduced by reaction with the hydroxyl group on the surface. In this case, L1 in the general formula (1) is preferably a linking group represented by any one of (2), (4), (6), (7), (15), and (21).

  In General formula (1), n represents the integer of 0-4, it is preferable that it is 0-2, and it is more preferable that it is 1-2. When n is an integer of 2 to 4, n L1s may be the same as or different from each other.

  In the general formula (1), R1 represents an organic group. The molecular weight of the organic group may be 1000 or less, or may exceed 1000.

  As an organic group having a molecular weight of 1000 or less, an alkyl group (preferably having 1 to 36 carbon atoms, more preferably 1 to 18 carbon atoms; for example, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group), an aryl group (preferably Has 6 to 36 carbon atoms, more preferably 6 to 24 carbon atoms; for example, phenyl group, biphenyl group, naphthyl group and the like, alkoxy group (preferably 1 to 36 carbon atoms, more preferably 1 to 18 carbon atoms; Methoxy group, ethoxy group, isopropoxy group, etc.), acyl group (preferably having 2 to 36 carbon atoms, more preferably 2 to 18 carbon atoms; for example, acetyl group, propionyl group, butyryl group, etc.), acylamino group (preferably 1 to 36 carbon atoms, more preferably 1 to 18 carbon atoms; for example, formylamino group, acetylamino group, etc.), aryl Oxy groups (preferably having 6 to 36 carbon atoms, more preferably 6 to 24 carbon atoms; for example, phenoxy group), cyano groups, silyl groups (for example, trimethylsilyl group, triphenylsilyl group, dimethylbutylsilyl group, etc.), etc. Is mentioned.

  The organic group may have a substituent. Examples of the substituent include a halogen atom, an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group), and an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 15 carbon atoms; , Phenyl group, biphenyl group, naphthyl group, etc.), alkoxy group (preferably 1-30 carbon atoms, more preferably 1-12 carbon atoms; for example, methoxy group, ethoxy group, isopropoxy group etc.), acyl group (preferably Has 2 to 36 carbon atoms, more preferably 2 to 18 carbon atoms; for example, acetyl group, propionyl group, butyryl group, etc.), acylamino group (preferably 1 to 36 carbon atoms, more preferably 1 to 18 carbon atoms; , Formylamino group, acetylamino group, etc.), aryloxy group (preferably having 6 to 36 carbon atoms, more preferably 6 carbon atoms). 18; for example, phenoxy group, etc.), acyloxy group (preferably having 2 to 36 carbon atoms, more preferably 2 to 18 carbon atoms; for example, acetyloxy group, propionyloxy group, butyryloxy group, etc.), cyano group, hydroxyl group, A nitro group etc. are mentioned.

  As the organic group having a molecular weight exceeding 1000, a polymer or an oligomer can be used. When a polymer and an oligomer are bonded, it is preferable in that aggregation is suppressed by steric repulsion in the matrix. The polymer and oligomer may have the substituents shown above.

  Specific examples of the organic group that can be used in the present invention are illustrated below, but the organic group that can be employed in the present invention is not limited thereto.

(Dispersant)
The resin film of the present invention is characterized by containing a dispersant. In the present invention, the dispersant is used as a medium for uniformly dispersing crystalline cellulose.

  The dispersant is required to be a thermoplastic resin that is incompatible with the matrix resin described later and has a molecular weight of 1000 or more. The difference in refractive index between the dispersant and the matrix resin is preferably 0.2 or less. In the present invention, in consideration of these conditions, it is necessary to select a dispersant as in Examples described later.

  The dispersant according to the present invention is not particularly limited as long as it satisfies the above conditions, but preferred specific examples include diacetyl cellulose (DAC), cellulose triacetate (TAC), and cellulose acetate pro manufactured by Eastman Chemical Company. Pionate (CAP482-20, CAP141-20), a dispersing agent (DISPERBYK180: BYK180, DISPERBYK: DISPERBYK: BYK184, BYK9076) manufactured by BYK Japan, Inc. can be used. Moreover, it is preferable to add 10-150 mass% of dispersing agents with respect to crystalline cellulose.

(Matrix resin)
The resin film of the present invention is characterized by containing a matrix resin. The matrix resin needs to be incompatible with the dispersant described above. The difference in refractive index between the matrix resin and the dispersant is preferably 0.2 or less. In the present invention, in consideration of these conditions, it is necessary to select a matrix resin as in Examples described later.

  Here, the “matrix resin” refers to a resin present around the crystalline cellulose used in the present invention. It is necessary to use a thermoplastic resin as the matrix resin.

  When a thermoplastic resin is used, it becomes easy to mold and the optical anisotropy of the resin film 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.

  In the present invention, the matrix resin is required to be incompatible with the above-described dispersant, but the incompatible resin in which the difference in refractive index between the matrix resin and the dispersant is 0.2 or less. Preferred combinations include cellulose acetate propionate (for example, CAP141-20; manufactured by Eastman Chemical Company), cellulose triacetate (TAC), and cellulose acetate propionate (for example, CAP482-20; manufactured by Eastman Chemical Company). ) And diacetyl cellulose (DAC), cellulose acetate propionate and cellulose triacetate (TAC), cellulose acetate propionate and acrylic resin, cellulose acetate propionate and polycarbonate (PC), acrylic resin and cellulose Triacetate (TAC), and the like.

  In the present invention, the mixing mass ratio of the matrix resin and the crystalline cellulose is usually 1: 0.01 to 3, preferably 1: 0.01 to 2, and more preferably 1: 0.02 to 2. More preferably, it is 1: 0.03-1.

  In the present invention, components other than the crystalline cellulose and the matrix resin may be contained. 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, and cellulose butyrate, 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 specification and the like 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.

  In addition, it is preferable that it is flexible as a base material of the resin film which concerns on this invention. 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>
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.

<Judgment of compatible state>
Whether the dispersant resin and the matrix resin are in a compatible state can be determined from the glass transition temperature Tg.

  When both resins are simply mixed, there are two glass transition temperatures for each resin because there is a glass transition temperature for each resin. However, when both resins are compatible, each glass has its own glass transition temperature. The temperature disappears and becomes one glass transition temperature, which becomes the glass transition temperature of the compatible resin.

The glass transition temperature T _g1,2 of the mixture in this compatible state is _expressed by the Gordon-Taylor equation (M. Gordon and JS Taylor, 2 J. of Applied).
Chem. 493-500 (1952)). :
T _g1,2 = (w ₁ T _g1 + Kw ₂ T _g2 ) / (w ₁ + Kw ₂ )
[Where w ₁ and w ₂ are mass fractions of constituent 1 (dispersant resin) and constituent 2 (matrix resin); T _g1 and T _g2 are constituents 1 and 2, respectively. Is the glass transition temperature (Kelvin temperature); T _g1,2 is the glass transition temperature of the mixture of components 1 and 2; K is a constant for the free volume of the two resins. ]
The glass transition temperature here is a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer) in which a sample stored for 24 hours in an atmosphere of 23 ° C. and 55% RH is placed in the same atmosphere. Then, it is measured at a rate of temperature increase of 20 ° C./min in a nitrogen stream, and is defined as the midpoint glass transition temperature (Tmg) determined according to JIS K7121 (1987).

  The test can be as follows. First, a particle, for example, 10 g of titanium oxide is sufficiently kneaded with 10 g of a dispersing agent with a biaxial kneader, dissolved in 200 g of methylene chloride, and subjected to an ultrasonic dispersing machine to prepare a domain particle dispersion.

  Next, 60 g of the matrix resin constituting the support medium is dissolved in this particle dispersion, and after applying to an ultrasonic disperser, it is cast on a glass plate so as to have a dry film thickness of 80 μm and dried to prepare a test film.

  By observing this test film with an electron microscope, it can be confirmed that the domains containing the particles are phase-separated in the support medium.

  When phase separation occurs, it is observed that particles are dispersed in the domain. If no phase separation has occurred, the particles are present throughout the test film.

  When the same test was performed without adding particles to the dispersing agent constituting the domain, the refractive index was very close to that of the matrix resin constituting the support medium, and both materials caused phase separation by electron microscopy. It is extremely difficult to confirm that

(Plasticizer)
The resin film 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 plasticizer. Agents, glycolate plasticizers, citrate plasticizers, polyester plasticizers, polyhydric alcohol ester plasticizers, and 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 film 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 film)
As a method for producing the resin film 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 viewpoint of suppression of defects and suppression of optical defects such as die line, a solution casting method and a melt casting method by a casting method are preferable.

  Hereinafter, the manufacturing method in the case of producing the resin film of this invention as a typical example is explained in full detail.

<Method for producing resin film by solution casting method>
(Organic solvent)
When the resin film of the present invention is produced by a solution casting method, any 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 resin film according to the present invention (hereinafter also simply referred to as “film”) 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 In this 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, a drying device 35 that transports the web alternately through rolls arranged in the drying device and / or a tenter stretching device 34 that clips and transports both ends of the web with clips. And 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 process This is a process in which the amount of residual solvent in the web becomes 2% by mass or less, and is taken up by the winder 37 as a 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 film by melt casting method>
The method in the case of manufacturing the resin film 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. Moreover, when touching with air, such as an exit from a feeder part or die | dye, it is preferable to set it as atmosphere, such as dehumidified air and dehumidified N2 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 defects are also referred to as die lines, but in order to reduce surface defects such as die lines, 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.

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

  In the present invention, it is preferable to add an apparatus 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 1
(Preparation of cellulose nanowhisker dispersion 1)
Asahi Kasei Co., Ltd. Theolas ST-100 was charged into a mixed solvent of methylene chloride and ethanol in which CAP141-20 was dissolved at a concentration of 2.2% to a concentration of 1%, and zirconia beads having an average particle size of 0.3 mm were used. The dispersion was performed for 90 minutes with a bead disperser. A mixed dispersion of methylene chloride and ethanol of cellulose nanowhiskers was obtained. A part of this dispersion was taken out and the methylochrome was evaporated, and then 100 cellulose nanofibers were observed with an electron microscope and measured to have an average fiber diameter of 100 nm and an average fiber length of 600 nm.

(Preparation of cellulose nanofiber dispersion 2)
Surface treatment of cellulose nanofibers 0.063 g of TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl (2,2) was added to a fiber obtained by treating sulfite bleached softwood pulp equivalent to 5 g in dry mass with a high-pressure homogenizer. , 6,6-tetramethylpiperidine 1-oxyl)) and 0.63 g of sodium bromide in 375 ml of water, 13% by weight sodium hypochlorite aqueous solution was added to 1 g of pulp with sodium hypochlorite. Hypochlorous acid was added to start the reaction so that the amount of was 2.5 mmol. 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 washed with 300 ml of ethanol, and then the substitution with acetone was repeated to completely remove moisture and alcohol components in the medium.

  Next, 1.9 equivalents of acetic anhydride and 2.7 equivalents of acetic acid were added to a toluene solvent containing 5 g of the fiber prepared above and 25 ml of toluene in a 100 ml three-necked flask equipped with a magnetic stirrer for 10 minutes. Stir.

Thereafter, 0.04 equivalent of 60% strength HClO ₄ was added and stirred for 5 minutes.

  After completion of the reaction, the product was obtained by filtration after washing with toluene / methanol. Further, the solid was added to a 200 ml beaker, dispersed in 20 ml of methanol and 10 ml of pure, neutralized with a 0.5N aqueous sodium hydroxide solution, and stored in ethanol.

  Dispersion was carried out by the same means as the preparation of Dispersion 1 except that CAP482-20 was used instead of CAP141-20.

(Preparation of cellulose nanofiber dispersion 3)
The fiber obtained by treating the sulfite bleached softwood pulp equivalent to 5 g in dry mass with a high-pressure homogenizer was completely replaced with ethanol and acetone to remove the water and alcohol components in the same manner as in the dispersion 2, and then 10 minutes under the same conditions. Stir. The product was stored in ethanol.

  Dispersion was made in the same manner as Dispersion 1 except that RW0057B from Eastman Chemical Company (hereinafter abbreviated as “ECC”) was used.

(Preparation of cellulose nanofiber dispersion 4)
The fiber obtained by treating the sulfite-bleached softwood pulp equivalent to 5 g in dry mass with a high-pressure homogenizer was completely replaced with ethanol and acetone to remove water and alcohol components in the same manner as dispersion 2. Stir. The product was stored in ethanol.

  Dispersion was made in the same manner as dispersion 1 except that ECC RW0057B was used.

(Preparation of cellulose nanofiber dispersion 5)
The fiber obtained by treating the sulfite-bleached softwood pulp equivalent to 5 g in dry mass with a high-pressure homogenizer was completely replaced with ethanol and acetone to remove water and alcohol components in the same manner as in dispersion 2, and then for 20 minutes under the same conditions. Stir. The product was stored in ethanol.

  Dispersion was made in the same manner as dispersion 1 except that ECC RW0057B was used.

(Preparation of cellulose nanofiber dispersions 6-8)
(Meth) acrylic polymer: A glass flask equipped with a stirrer, two dropping funnels, a gas introduction tube and a thermometer was charged with 40 g of MMA, 3.0 g of a mercaptopropionic acid chain transfer agent and 30 g of toluene, and the temperature was 90 ° C. The temperature rose. Thereafter, 60 g of the monomer was dropped from one dropping funnel over 10 minutes, and 0.6 g of azobisisobutyronitrile dissolved in 14 g of toluene was dropped from the other funnel over 10 minutes. Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was added dropwise over 10 minutes, and the reaction was further continued for 10 minutes to obtain a (meth) acrylic polymer.

  The molecular weight was adjusted according to the reaction time.

  These were prepared in the same manner as in Example 1 as a dispersant.

<Preparation of crystalline cellulose-containing film 1>
Subsequently, using the produced cellulose nanowhisker dispersion liquid 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 liquid.

(Preparation of dope solution)
Triacetyl cellulose 120 parts by weight Cellulose nanowhisker dispersion 1 840 parts by weight (20 parts by weight as MFC solids)
Plasticizer (trimethylolpropane tribenzoate) 10 parts by mass <Preparation of crystalline cellulose-containing films 2 to 8>
Using the matrix material of Table 1, a crystalline cellulose-containing film was produced in the same manner as described above.
(Comparative example)
<Preparation of Comparative Example Dispersion 1>
It was prepared in the same manner as dispersion 6 except that the dispersant was methyl methacrylate (MMA; manufactured by Wako Pure Chemical Industries, Ltd.).

<Preparation of dispersion of Comparative Example 2>
A dispersion was prepared in the same manner as Dispersion 1 except that the materials shown in Table 1 were used. Moreover, it added to the tetrabutylammonium hydroxy aqueous solution, and the surfactant adsorption | suction cellulose crystal | crystallization was obtained by freeze-drying.

<Preparation of dispersion of Comparative Example 3>
A dispersion was prepared in the same manner as Dispersion 1 except that the materials shown in Table 1 were used.

<Preparation of dispersion of Comparative Example 4>
A film was obtained by adding methyl methacrylate (MMA; manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersant to epoxy acrylate beam set 371 (manufactured by Arakawa Chemical Industries, Ltd.) and heating for 120 minutes.

<Comparative Example 5>
The mixture was stirred for 60 minutes by the same method as that of dispersion 3, and was prepared by the same method as that of dispersion 3 by using no dispersant.

<Evaluation>
The following evaluation was performed using the various films produced above.

(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 increased at a rate of 5 ° C. per minute, and the value at 30 ° C. 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 then held for 30 minutes. The temperature was raised again at a rate of 5 ° C. per minute, and the value at 50 ° C. 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.

(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.

(Confirmation of incompatibility)
A melting peak was measured with a differential operation calorimeter (DSC) EXSTAR DSC6000 series (manufactured by Seiko Instruments Inc.), and two peaks of a matrix and a dispersant were confirmed.

(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 the 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 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roll)
6 Nipping pressure rotating body (touch roll)
7 Rotating support (second cooling roll)
8 Rotating support (3rd cooling roll)
DESCRIPTION OF SYMBOLS 9 Peeling roll 10 Film 11, 13, 14 Conveyance roll 12 Stretching machine 15 Slitter 16 Winding machine F Resin film of this invention

Claims (5)

  A resin film containing crystalline cellulose, a dispersant, and a matrix resin, wherein the degree of substitution of the hydroxyl group of the crystalline cellulose with an acyl group is in the range of 0 to 2.5, and the average of the crystalline cellulose A resin having a minor axis diameter of 2 μm or less, the dispersant being incompatible with the matrix resin, a molecular weight of 1000 or more, and the matrix resin being a thermoplastic resin the film.   The resin film according to claim 1, wherein a difference in refractive index between the dispersant and the matrix resin is 0.2 or less.   The said substitution degree exists in the range of 0-2.0, The resin film of Claim 1 or Claim 2 characterized by the above-mentioned.   The resin film according to any one of claims 1 to 3, wherein the matrix resin contains 1% by mass or more of a cellulose ester resin.   It is a manufacturing method of a resin film, Comprising: The manufacturing method of the resin film characterized by manufacturing the resin film as described in any one of Claim 1- Claim 4.

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