JPWO2009119153A1 - Optical film, polarizing plate - Google Patents

Abstract

An object of the present invention is to provide an optical film that is excellent in handling properties such as slitting properties and has dimensional stability even when stored under high temperature and high humidity. It is another object of the present invention to provide a polarizing plate using this optical film and having no performance deterioration even in long-term use. The above object of the present invention has been achieved by an optical film characterized by containing silica particles doped with at least one metal element in an optical film having a haze value in the range of 0.0 to 0.5. .

Description

  The present invention relates to an optical film excellent in handleability and excellent in dimensional stability even under high temperature and high humidity, and a polarizing plate using the optical film.

  Various optical films such as a retardation film and a polarizing plate protective film are used in the liquid crystal display device, and the optical film is provided with slitting properties, slipperiness between optical films, transportability, winding quality, and pasting. Usually, particles such as silica are added for handling such as prevention of sticking failure (Patent Document 1).

  In addition, the silica surface is subjected to a hydrophobization treatment (Patent Document 2) for the purpose of improving productivity such as particle dispersibility and filterability (Patent Document 3). Such a technique is also disclosed.

On the other hand, the problem that optical films containing silica particles are inferior in dimensional stability under high temperature and high humidity has recently been clarified.
JP 2002-194106 A JP-A-7-11055 Japanese Patent Application Laid-Open No. 2004-359736

  An object of the present invention is to provide an optical film that is excellent in handling properties such as slitting properties and excellent in dimensional stability even when stored under high temperature and high humidity. Another object is to provide an optical film excellent in coatability with few cissing failures even when used as a support.

  Another object of the present invention is to provide a polarizing plate using this optical film, which does not deteriorate in performance even after long-term use.

  More specifically, an object of the present invention is to provide a highly productive optical film that eliminates clogging of the kneader during melt-kneading and is excellent in the quality of prepared pellets.

  The object of the present invention has been achieved by the following constitution.

  1. An optical film having a haze value in the range of 0.0 to 0.5, comprising silica particles doped with at least one metal element.

  2. 2. The optical film as described in 1 above, wherein the metal element is selected from aluminum, titanium, zinc, zirconium and magnesium.

  3. A polarizing plate using the optical film described in 1 or 2 above.

  It is an object of the present invention to provide an optical film that is excellent in handling properties such as slitting properties and excellent in dimensional stability even in storage under high temperature and high humidity. Another object was to provide an optical film excellent in coatability with few cissing failures even when used as a support.

  In addition, a polarizing plate using this optical film and having no performance deterioration even after long-term use could be provided.

  More specifically, it was possible to provide a highly productive optical film that eliminates clogging of the kneading machine during melt kneading and is excellent in the quality of the prepared pellets.

It is a general | schematic flow sheet which shows one embodiment of the apparatus which enforces the manufacturing method of the cellulose-ester film which concerns on this invention. It is a principal part expansion flow sheet of the manufacturing apparatus of FIG.

Explanation of symbols

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)
9, 11, 13, 14, 15 Transport roll 10 Film 12 Stretcher 16 Winding device

<Basic structure of optical film>
The optical film of the present invention is a silica particle doped with at least one element selected from aluminum, titanium, zinc, zirconium and magnesium (hereinafter referred to as metal-doped silica). (Abbreviated as “particle”).

  The mechanism by which the metal-doped silica particles of the present invention suppress the deterioration of the dimensional stability of the optical film under high temperature and high humidity is estimated as follows.

  Silanol groups exist on the surface of the silica particles, and the silanol groups take in moisture in the atmosphere, and the taken-in moisture acts on the polymer forming the film to change the size.

  In the metal-doped silica particles of the present invention, the doped metal acts on the silanol group and lowers the action of taking moisture from the atmosphere, so the action of moisture on the polymer forming the film is reduced, and as a result, the optical film Dimensional change is reduced.

  Since this metal-doped silica particle is modified with a metal doped with silanol groups present on the particle surface, the distribution of the secondary particle size when dispersed is narrower than that of undoped silica particles, and the optical film It also contributes to transparency.

Usually, the haze is increased by adding particles such as silica. However, in the metal-doped silica particles of the present invention, the haze of the optical film may be 0.0 to 0.5 while maintaining the handleability of the optical film. it can.
<Metal-doped silica particles>
Examples of the method for producing the metal-doped silica particles of the present invention include a method of reacting aluminum, zinc or titanium chelate compounds in a dry or wet manner with pure silica particles once prepared, or titanic acid as a silica raw material. And a method of mixing a trace amount of zirconic acid and the like.

  In the present invention, the most preferable production method is to co-combust the metal chloride when producing vapor phase silica by combustion. Reference can be made to the method described in JP-A-2004-143028.

  Specifically, in the case of aluminum, as a method for producing alumina-doped silica particles, silica particles are put in a solution containing aluminum chloride, the surface of the silica particles is coated with the aluminum chloride solution, and this is dried and fired. And a method of gasifying an aluminum halide compound and a silicon halide compound and reacting the mixed gas in a flame.

  As the alumina-doped silica particles of the present invention, those produced by a combination of a thermal decomposition method and a flame hydrolysis method can be used.

According to this method, a small amount of alumina can be uniformly doped on the surface of the silica particles. In this method, gasified silicon halide (such as SiCl ₄ CH ₃ SiHCl ₂ HSiCl ₃ CH ₃ SiCl ₃ ) is sent into an oxygen hydrogen flame burner and reacted with the aerosol in the flame.

  As the aerosol, an aluminum compound such as aluminum chloride is used. This aerosol is prepared by spraying a solution or dispersion containing an aluminum compound with an aerosol generator, for example, an ultrasonic generator.

  This aerosol is introduced into the burner and reacted together with the vaporized silicon halide. This produces alumina-doped silica whose surface is doped with alumina. Since hydrogen halide gas is generated as a by-product, it is separated and recovered.

  The alumina-doped silica thus produced is not produced as separate particles of alumina and silica, and unlike the mixed oxide in which alumina and silica are mixed in one particle, the alumina-doped silica is formed on the surface layer of silica particles. The particles are doped with alumina.

  Other metals can be prepared in the same manner. For example, the method for producing fine particles described in JP 2007-137984 A, JP 03-75302 A, 07-53268, and 07-54008 Can be used to produce fine particles in which different types of oxides are combined. These are also included as the metal-doped silica of the present invention.

  These metal-doped silica particles are preferably further hydrophobized. As hydrophobizing agents, silane coupling agents such as trimethylsilyl chloride and epoxy silane, silicone oils such as polydimethylsiloxane, silazanes such as hexamethyldisilazane, etc. are used, and one or more of these hydrophobizing agents are mixed. Can be used.

  The amino group-containing silane coupling agent and amino group-containing silicone oil can also be used as a charge adjusting agent.

  The method of hydrophobizing treatment is performed, for example, by placing fine powder in a container equipped with a stirring device, stirring under a nitrogen atmosphere, and using the hydrophobizing agent alone or the hydrophobizing agent and the charge adjusting agent as needed. In addition, the hydrophobized silica particles of the present invention can be obtained by a dry treatment method in which a hydrophobizing agent or the like is vaporized by heating or vaporized and sufficiently dispersed with fine powder, then heated and then cooled.

  Although the preferable dope amount of a metal element changes with kinds of metal, the range of 0.5 to 40% is preferable at the element molar ratio with respect to silicon.

  In order to exhibit a clear effect, it is 0.5% or more, and in order to maintain dispersibility and transparency, it is preferably 40% or less.

The average primary particle size of the silica particles of the present invention is preferably 5 to 100 nm from the viewpoint of transparency. As the metal-doped particles of the present invention, commercially available products such as Aerosil MOX 170, 80 (manufactured by Nippon Aerosil Co., Ltd.) can be used, but the type and amount of the metal to be appropriately doped depending on the characteristics of the optical film. It is preferable to change.
<Polymer forming film>
As the polymer that forms the optical film of the present invention, a normal polymer that can be used for optical applications and can form a film can be used. Cellulose ester, polycarbonate, polysulfone, polyethersulfone, Those selected from polyacrylates, acrylic polymer-containing cellulose esters and polycycloolefins are preferred, and cellulose esters, polycycloolefins, polyacrylates, acrylics are particularly easy to adjust the phase difference when used as an optical film. It is preferable to select from a polymer-containing cellulose ester and polycarbonate.

  As these polymers, those produced by ordinary known production methods and those commercially available can be used.

  Examples of the polyacrylate of the present invention include Delpet 60N, 80N (Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry ( Etc.).

  Examples of commercially available polycycloolefins include ZEONEX, ZEONOR (manufactured by ZEON Corporation), ARTON (manufactured by JSR Corporation), TOPAS (manufactured by TICONA Corporation), and APEL (manufactured by Mitsui Chemicals, Inc.). Can be mentioned.

Examples of the cellulose ester of the present invention include the cellulose esters described below.
<Characteristics of optical film>
In the optical film of the present invention, when the refractive index in the slow axis direction in the plane of the film is nx, the refractive index in the direction perpendicular to the slow axis in the plane is ny, and the refractive index in the thickness direction is nz, An optical film having a retardation as described below is preferable.

Film thickness: 20-70 μm
0nm ≦ Ro ≦ 330nm
−200 nm ≦ Rt ≦ 500 nm
1.1 ≦ Rt / Ro ≦ 10
The measurement wavelengths of Ro and Rt are 590 nm, Ro = (nx−ny) × d, and Rt = {(nx + ny) / 2−nz} × d, where d represents the film thickness (nm) of the optical film.

  Examples of the method for adjusting the retardation in the optical film of the present invention as described above include the following methods.

  For example, the polycycloolefin film is preferably subjected to an appropriate stretching treatment.

For example, the cellulose ester film is preferably subjected to an appropriate stretching treatment, and the rod-like polarizability anisotropy represented by the following formula (1) is 300 × 10 ⁻²⁵ cm ³ or more and 2000 × 10 ⁻²⁵ cm ^3. A compound having a molecular end-to-end distance of 2 nm to 10 nm and a plane polarizability anisotropy represented by Formula (2) of 300 × 10 ⁻²⁵ cm ^{3 to} 1500 × 10 ⁻²⁵ cm ³ A compound having an end-to-end distance of 2 nm to 10 nm, an acrylic polymer, and at least one of at least one of a pyranose structure or a furanose structure and having all or part of OH groups in the structure esterified A cellulose ester film containing at least one ester compound is preferable.

Formula (1): Δα1 = αx− (αy + αz) / 2
Formula (2): Δα2 = (αx + αy) / 2−αz
(Where αx is the largest component of the eigenvalues obtained after diagonalizing the polarizability tensor; αy is the second largest component of the eigenvalues obtained after diagonalizing the polarizability tensor. Yes; αz is the smallest component of the eigenvalues obtained after diagonalizing the polarizability tensor.)
<Compound represented by formula (1) or (2)>
The compound represented by the formula (1) or (2) of the present invention acts as a retardation increasing agent for increasing the so-called cellulose ester retardation.

  The end-to-end distance of the retardation increasing agent of the present invention needs to be 2 nm or more and 10 nm or less for the function expression.

  The end-to-end distance can be obtained from the optimized molecular structure by calculation using the molecular orbital method or the density functional method.

  The retardation increasing agents used in the present invention are roughly classified into two types. The first is the type represented by the mathematical formula (1) having a large rod-like polarizability anisotropy of the molecule, and the second is the formula represented by the mathematical formula (2) having a large planar polarizability anisotropy of the molecule. It is.

  For these compounds, the compounds described in JP-A-2006-193724 can be referred to.

  It is necessary to add at least one of the retardation increasing agents having a large plane polarizability anisotropy of the molecule to the cellulose in an amount of 0.1 to 30% by mass, preferably 0.5 to 20% by mass. More preferably, it is 1-15 mass%, Most preferably, it is 1-10 mass%. When using 2 or more types, it is preferable that the total amount satisfy | fills said range.

  In addition, the retardation increasing agent having a large rod-like polarizability anisotropy of the molecule of the present invention and a retardation increasing agent having a large planar polarizability anisotropy of the molecule can be used to suppress bleed out more effectively. And particularly preferred.

  When using together, it is preferable that the total amount satisfy | fills the same numerical range as said one type of case. The mixing ratio of these retardation increasing agents is 0.01 to 100 parts by mass of a retardation increasing agent having a large planar polarizability anisotropy with respect to 1 part by mass of the retardation increasing agent having a large rod-like polarizability anisotropy of the molecule. Is preferable, and 0.1-10 mass parts is further more preferable.

<Acrylic polymer>
The optical film of the present invention may contain an acrylic polymer. Here, the acrylic polymer includes a methacrylic polymer. The total amount of the resin in the optical film may be an acrylic polymer, or may be used in combination with other resins, and the content can be arbitrarily selected within the range of 0 to 100%. In the present invention, it is most preferable to use in combination with a cellulose ester.

  As an acrylic polymer used in the present invention, when used in combination with a cellulose ester film, it preferably exhibits negative birefringence as a function of the stretching direction, and the structure is not particularly limited. It is preferable that a polymer having a weight average molecular weight of 500 or more and 1000000 or less obtained by polymerizing a polymerizable unsaturated monomer is appropriately selected.

  The proper molecular weight range of the acrylic polymer is as described above, but when it is contained in an amount of 30% by mass or more, the weight average molecular weight is preferably 80,000 to 1,000,000 from the viewpoint of compatibility with the cellulose ester.

  The weight average molecular weight of the acrylic polymer of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

  The acrylic polymer can be directly added and dissolved as a material constituting the dope liquid described later, or can be added to the dope liquid after being previously dissolved in an organic solvent for dissolving the cellulose ester.

<Ester compound in which at least one of pyranose structure or furanose structure is 1 or more and 12 or less and all or part of OH groups of the structure are esterified>
The cellulose ester film of the present invention is characterized by comprising an ester compound having at least one pyranose structure or at least one furanose structure and having all or part of OH groups in the structure esterified.

  The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

  In the present invention, ester compounds are collectively referred to as sugar ester compounds.

  Examples of the ester compound of the present invention include the following, but the present invention is not limited thereto.

  Glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose or tose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  As examples, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are preferable, and sucrose is more preferable.

  Specifically, glucose pentaacetate, glucose pentapropionate, glucose pentabtylate, saccharose octaacetate, saccharose octabenzoate and the like can be preferably mentioned, and among these, saccharose octaacetate and saccharose octabenzoate are more preferable, and saccharose Octabenzoate is particularly preferred.

  Monopet SB (Daiichi Kogyo Seiyaku Co., Ltd.) etc. can be used as a commercial item.

  The cellulose ester film of the present invention preferably contains the ester compound of the present invention in an amount of 1 to 30% by mass of the cellulose ester film in order to suppress the fluctuation of the retardation value and stabilize the display quality. 5 to 30% by mass is preferable.

<Cellulose ester>
The cellulose ester of the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, may be an aromatic carboxylic acid ester, and is particularly preferably a lower fatty acid ester having 6 or less carbon atoms.

  The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  Specifically, the cellulose ester includes cellulose acetate propionate, cellulose acetate butyrate, or a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate butyrate. Can be used.

  The butyryl group that forms butyrate may be linear or branched. As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are particularly preferably used.

  Preferred cellulose esters other than cellulose acetate phthalate for the present invention preferably satisfy the following formulas (1) and (2).

Formula (1) 2.0 <= X + Y <= 3.0
Formula (2) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.

  Further, in order to obtain optical characteristics that meet the purpose, resins having different degrees of substitution may be mixed and used. The mixing ratio is preferably 100: 0 to 50:50 (mass ratio).

  Of these, cellulose acetate propionate is particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The weight average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000, since the mechanical strength of the resulting film is strong. Further, 75,000 to 280000 are preferably used.

<Other additives>
(Plasticizer)
The cellulose ester film of the present invention can contain a plasticizer as necessary to obtain the effects of the present invention.

  The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like.

  Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

(Antioxidant)
In this invention, it is preferable to use what is generally known as an antioxidant. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds having no metal atom can be preferably used.

  As the lactone compound of the present invention, those commercially available under the trade name HP-136 from Ciba Japan Co., Ltd. are preferable.

  The phenolic compound preferably has a 2,6-dialkylphenol structure. For example, Ciba Japan Co., Ltd., “Irganox 1076”, “Irganox 1010”, “Irgafos XP40”, “Irgafos XP60”, Co., Ltd. ADEKA What is marketed with the brand name "ADK STAB AO-50" is preferable.

  Examples of the phosphorus-based compound having no metal atom include Sumitizer GP from Sumitomo Chemical Co., Ltd., ADK STAB PEP-24G from Adeka Co., Ltd., “ADK STAB PEP-36”, “ADK STAB 2112” and What is marketed by the brand name "ADK STAB 3010", the product name "IRGAFOS P-EPQ" from Ciba Japan Co., Ltd., and "GSY-P101" from Sakai Chemical Industry Co., Ltd. is preferable.

  As the hindered amine compound, for example, those commercially available from Ciba Japan Co., Ltd. under the trade names of “Tinvin 144” and “Tinvin 770” and ADEKA Co., Ltd. as “ADK STAB LA-52” are preferable.

  As the sulfur compound, for example, those commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer TPL-R” and “Sumilizer TP-D” are preferable.

  The above-mentioned double bond compounds are preferably those commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer GM” and “Sumilizer GS”.

  Furthermore, as a commercially available epoxy group-containing epoxide resin compound, a compound having an epoxy group as described in EPON 815C, US Pat. No. 4,137,201 may be contained.

  The amount of these antioxidants and the like to be appropriately added is determined in accordance with the process at the time of recycling, but generally 0.05 to 20% by mass, preferably with respect to the resin as the main raw material of the film Is added in the range of 0.1 to 1% by mass.

  These antioxidants can obtain a synergistic effect by using several different types of compounds in combination rather than using only one kind. For example, the combined use of lactone, phosphorus, phenol and double bond compounds is preferred.

  In the present invention, the preferred embodiment of the cellulose ester is preferably washed in the presence of an antioxidant during suspension washing with a poor solvent.

  The antioxidant used inactivates the radicals generated in the polymer forming the film, or the deterioration of the polymer forming the film due to the addition of oxygen to the radical generated in the polymer forming the film. Any compound that can be used can be used without limitation.

  The antioxidant used for suspension washing of the polymer forming the film may remain in the polymer forming the film after washing. The remaining amount is preferably 0.01 to 2000 ppm, more preferably 0.05 to 1000 ppm. More preferably, it is 0.1-100 ppm.

  The antioxidant useful in the present invention can be used without limitation as long as it is a compound that suppresses the deterioration of the film forming material due to oxygen. Among them, as the useful antioxidant, phenolic compounds, hindered amine compounds And phosphorus compounds having no metal atoms, sulfur compounds, heat-resistant processing stabilizers, oxygen scavengers, etc. Among these, phenol compounds, hindered amine compounds, and phosphorus compounds having no metal atoms are particularly preferable. .

  By blending these compounds, it is possible to prevent coloring and strength reduction of the molded product due to heat, thermal oxidation degradation, and the like without reducing transparency, heat resistance, and the like. These antioxidants can be used alone or in combination of two or more.

  As with the polymer forming the film, the antioxidant preferably removes impurities such as residual acids, inorganic salts, and small organic molecules that are carried over from production or generated during storage, and more preferably purity. 99% or more. The residual acid and water are preferably from 0.01 to 100 ppm, and in the melt casting film formation of the polymer forming the film, thermal deterioration can be suppressed, film formation stability, film optical properties, machine Physical properties are improved.

  In the present invention, these antioxidants are each preferably added in an amount of 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, and further 0% to the polymer forming the film. It is preferable to add 2 to 2% by mass. Two or more of these may be used in combination.

(UV absorber)
The optical film of the present invention can also contain an ultraviolet absorber.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry film thickness of the polarizing plate protective film is 30 to 200 μm, it is 0.5 with respect to the polarizing plate protective film. 10 mass% is preferable, and 0.6-4 mass% is further more preferable.
<The manufacturing method of the optical film of this invention>
As a method for producing the optical film of the present invention, a known method can be used. For example, a dope in which a polymer for forming a film is dissolved in a solvent is prepared, and the solution is cast on an endless belt. Typical methods include a film method and a melt casting film forming method in which a polymer for forming a film is melted by heat and formed into a film shape with a roll or the like.

  These methods can be appropriately selected depending on the type of polymer forming the film.

  For polycarbonate, the solution casting film forming method is preferred, and for cellulose esters and polycycloolefins, both the solution casting film forming method and the melt casting film forming method can be adopted. The film forming method is preferred.

Hereinafter, cellulose ester will be described as a specific example.
<Melt casting film formation of cellulose ester film>
The method for producing a cellulose ester film of the present invention is a method for producing a cellulose ester film in which at least a cellulose ester, silica particles of the present invention and a plasticizer are mixed and melted, extruded from a die, and cast on a cooling roll.

  The entire manufacturing method will be described below.

<Melted pellet manufacturing process>
The mixture of the cellulose ester used for melt extrusion, the silica particles of the present invention, the plasticizer and other additives is preferably kneaded in advance and pelletized.

  Pelletization may be performed by a known method. For example, dry cellulose ester, plasticizer, and other additives are fed to an extruder using a feeder and kneaded using a single-screw or twin-screw extruder, and then formed into a strand from a die. It can be done by extrusion, water cooling or air cooling and cutting.

  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.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders. A small amount of an additive such as an antioxidant is preferably mixed in advance in order to mix uniformly.

  Mixing of the antioxidants may be performed by mixing solids, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with cellulose ester and mixed, or sprayed and mixed. Also good.

  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>
Using a single-screw or twin-screw type extruder, the melt temperature Tm when extruding the pellets is about 200-300 ° C, filtered with a leaf disk type filter, etc. Cast on the cooling roll, solidify on the cooling roll, and cast while pressing with the elastic touch roll.

  When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure or in an 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.

  The cooling roll of the present invention is not particularly limited, but is a roll having a structure in which a heat medium or a coolant that can be controlled in temperature flows through a highly rigid metal roll, and the size is not limited. The size 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 surface hardness 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, ceramic spraying, or the like.

  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.

  Examples of the elastic touch roll of the present invention include JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97-028950, JP-A-11-235747, JP-A-11-235747. A silicon rubber roll coated with a thin-film metal sleeve can be used as described in JP-A-2002-36332, JP-A-2005-172940 and JP-A-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, it is preferable that the film obtained as described above is further stretched 1.01 to 3.0 times in at least one direction after passing through the step of contacting the cooling roll. The sharpness of the streaks becomes gentle by stretching and can be highly corrected.

  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, in the case where the optical film is a retardation film that 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. On the other hand, the transmission axis of the polarizing film is also usually in the width direction. A good viewing angle can be obtained by incorporating in a liquid crystal display device a polarizing plate laminated so that the transmission axis of the polarizing film and the slow axis of the polarizing plate protective film are parallel to each other.

  When the cellulose ester film of the present invention is used as a film having an optical compensation function, the temperature and magnification can be selected so that desired retardation characteristics can be obtained.

  Usually, the draw ratio is 1.1 to 3.0 times, preferably 1.2 to 1.5 times, and the drawing temperature is usually Tg to Tg + 50 ° C. of the resin constituting the film, preferably Tg to Tg + 40 ° C. In the temperature range.

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

  For the purpose of adjusting the retardation of the cellulose ester film produced by the above method and reducing the dimensional change rate, the film may be contracted in the longitudinal direction or the width direction.

  In order to shrink in the longitudinal direction, for example, there is a method of contracting the film 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 in-plane retardation (Ro) and thickness direction retardation (Rt) of the cellulose ester film of the present invention can be appropriately adjusted, but Ro is preferably 0 to 200 nm and Rt is preferably −150 to 400 nm.

In addition, when the refractive index Nx in the slow axis direction of the film, the refractive index Ny in the fast axis direction, the refractive index Nz in the thickness direction, and the film thickness of the film are d (nm),
Ro = (Nx−Ny) × d
Rt = {(Nx + Ny) / 2−Nz} × d
Represented as: (Measurement wavelength 590nm)
The variation in retardation is preferably as small as possible, and is usually within ± 10 nm, preferably ± 5 nm or less, and more preferably ± 2 nm or less.

  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.

  In the cellulose ester film of the present invention, it is preferable that the height from the top of the adjacent mountain to the bottom of the valley is 300 nm or more, and there is no streak continuous in the longitudinal direction with an inclination of 300 nm / mm or more.

  The shape of the streak was measured using a surface roughness meter. Specifically, using a Mitutoyo SV-3100S4, a stylus (diamond needle) having a tip shape of a cone of 60 ° and a tip curvature radius of 2 μm was used. The film is scanned in the width direction of the film at a measurement speed of 1.0 mm / sec while applying a load of 0.75 mN, and a cross-sectional curve is measured with a Z-axis (thickness direction) resolution of 0.001 μm.

From this curve, the streak height reads the vertical distance (H) from the top of the mountain to the bottom of the valley. The slope of the streak is obtained by reading the horizontal distance (L) from the top of the mountain to the bottom of the valley and dividing the vertical distance (H) by the horizontal distance (L).
<Cleaning equipment>
It is preferable to add an apparatus for automatically cleaning the belt and the roll to the manufacturing apparatus of the present invention. 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.
<Solution casting film formation of cellulose ester film>
1) Dissolving step A step of dissolving a cellulose ester, the silica particles of the present invention and other additives in an organic solvent mainly containing a good solvent for cellulose ester while stirring, or forming a dope, or a cellulose ester solution In addition, the silica particles of the present invention and other additive solutions are mixed to form a dope which is a main solution.

  For dissolution of the cellulose ester, 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 method as described in JP-A-9-95538 and a high-pressure method as described in JP-A-11-21379 can be used. A method in which pressure is applied at a boiling point or higher is preferred.

  The total amount of cellulose ester in the dope is preferably in the range of 15 to 45% by mass. After the additive is added to the dope during or after dissolution, the dope is dissolved and dispersed, filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Filtration is preferably performed using a filter medium having a collected particle size of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml.

  In this method, the aggregate remaining at the time of particle dispersion and the aggregate generated when the main dope is added are only aggregated by using a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. Can be removed. In the main dope, the concentration of particles is sufficiently thinner than that of the additive solution, so that aggregates do not stick together at the time of filtration and the filtration pressure does not increase suddenly.

  Thereafter, the main dope solution is filtered through a main filter, and the silica particle dispersion of the present invention is optionally added in-line.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material. The return material may contain the silica particles of the present invention. In that case, it is preferable to control the addition amount of the silica particle addition liquid in accordance with the addition amount of the return material.

  The return material is a product obtained by finely pulverizing the cellulose ester film of the present invention, and a material obtained by forming both sides of the film, which is generated when the film is formed, or a raw material which is speculated out by scratches or the like is used.

  Moreover, what was knead | mixed beforehand and pelletized can be used preferably.

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, and the like. 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. When peeling off when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling may be impaired, and slippage and vertical stripes may occur due to peeling tension. The amount of residual 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 35 that alternately feeds the web through a plurality of rolls arranged in the drying device, or a tenter stretching device 34 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.

  The stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the 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.

  30-150 degreeC is preferable, as for the drying temperature in the case of performing a tenter, 50-120 degreeC is more preferable, and 70-100 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 As a winding method, a generally used method may be used, such as a constant torque method, a constant tension method, a program tension control method with a constant internal stress, and the like.
<Polarizing plate using optical film of the present invention as polarizing plate protective film>
The optical film of the present invention may be at least one of the polarizing plate protective films in the polarizing plate of the present invention comprising a polarizer and two polarizing plate protective films sandwiching the polarizer.

  A polarizer is an element that allows only light of a polarization plane in a certain direction to pass through. A typical polarizer currently known is a polyvinyl alcohol polarizing film, which is obtained by staining a polyvinyl alcohol film with iodine. Some of them are dyed with dichroic dyes.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. The film thickness of the polarizer is preferably 5 to 30 μm, particularly preferably 10 to 20 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. Ethylene-modified polyvinyl alcohol is also preferably used.

  Among these, an ethylene-modified polyvinyl alcohol film having a cutting temperature with hot water of 66 to 73 ° C. is preferably used. The difference in the cutting temperature by hot water between two points 5 cm away in the TD direction of this film is more preferably 1 ° C. or less in order to reduce color spots, and between two points 1 cm away in the TD direction of the film It is more preferable that the difference in cutting temperature with hot water is 0.5 ° C. or less in order to reduce color spots.

  A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.

  The polarizing plate of the present invention can be produced by a general method. That is, it is preferable that the polarizer side of the cellulose ester film as the optical film of the present invention is subjected to alkali saponification treatment and is bonded to at least one surface of a polarizer prepared by immersion and stretching in an iodine solution.

  Examples of the adhesive used for pasting include a PVA (polyvinyl alcohol) -based adhesive and a urethane-based adhesive, among which a PVA-based adhesive is preferably used.

  The in-plane slow axis of the optical film of the present invention and the absorption axis of the polarizer are preferably bonded orthogonally or at 45 °. This angle can be appropriately selected depending on the suitability of the liquid crystal display device.

  Here, the axis being orthogonal, 45 °, or parallel or horizontal means that it is in a range of ± 7 degrees with respect to a strict angle, and preferably is ± 4 degrees.

  Even if it uses this optical film for the other surface, it is preferable to bond with another polarizing plate protective film.

  For example, a commercially available cellulose ester film (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4UE, KC8UE, KC8UY-HA, KC8UY-HA, KC8UY-C8 -RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are also preferably used.

The polarizing plate protective film used on the surface side of the display device preferably has an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer in addition to the isotropic layer or the clear hard coat layer.
<Liquid crystal display device using the polarizing plate of the present invention>
The optical film and polarizing plate of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB.

  In particular, even a large-screen liquid crystal display device with a 30-inch or larger screen can provide a liquid crystal display device with excellent visibility such as uneven coloring and front contrast with little environmental fluctuation and reduced light leakage.

  The driving liquid crystal cell has a structure in which a driving circuit is provided on two transparent supports, such as a glass plate and a transparent resin film, which are used in a normal liquid crystal display device, and liquid crystal is enclosed. Can be used in the usual way.

Example 1
<Melting cast cellulose ester film>
The following kneading | mixing examination for producing the pellet for melt casting film forming was performed using the composition of the cellulose ester of this invention, the silica particle of this invention, and various additives as follows.

Cellulose acetate propionate (acetyl group substitution degree 1.6, propionyl group substitution degree 1.2, Mn = 86,000, Mw / Mn = 2.5) 100 parts by mass Pentaerythritol tetrabenzoate 8.0 parts by mass IRGANOX 1010 ( Ciba Japan Co., Ltd.)
0.50 parts by mass Sumizer GS (manufactured by Sumitomo Chemical Co., Ltd.) 0.20 parts by mass GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.) 0.25 parts by mass The silica particles of the present invention are shown in Table 1.
(Hydrophobic treatment was performed with hexamethyldisilazane)
TINUVIN928 (Ciba Japan Co., Ltd.) 1.5 parts by mass

  The cellulose ester was dried under reduced pressure at 70 ° C. for 3 hours and cooled to room temperature, and then the additive was mixed.

  The above mixture was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized. In addition, the glass transition temperature Tg of this pellet was 136 degreeC.

The results of the kneading study are shown in Table 1.
<Clogging of kneading machine>
The occurrence frequency of raw material clogging near the inlet of the kneader was evaluated according to the following index.
○: No clogging occurs in 8 hours of continuous operation ○ to Δ: Raw material clogging occurs once in 8 hours Δ: Raw material clogging occurs in 2 to 3 times out of 8 hours Δ to ×: Within 8 hours Occurrence of raw material clogging at a frequency of 4-5 times x: Occurrence of raw material clogging at a frequency of 6 times or more in 8 hours <coarse particles>
The prepared pellet was made into a thin piece and subjected to TEM observation (JEM-2010F field emission electron microscope manufactured by JEOL Ltd., magnification 2500 times, 20 μm square field, 20 field). It was checked whether particles of 1 μm or more were present.
<Pellet powder falling>
The prepared pellets were shaken with a tumbler mixer at a filling rate of 80%, passed through a 1 mm mesh sieve, and the mass of the fallen powder was expressed as a ratio to the original pellets and evaluated according to the following criteria.
○: 0.0 to 0.5% by mass
○ to Δ: 0.5 to 1.0 mass%
Δ: 1.0-3.0 mass%
Δ to ×: 3.0 to 10.0% by mass
×: 10.0% by mass or more

As described above, the pellets using the metal-doped silica particles of the present invention have a high evaluation such as clogging of the kneader and contribute to the productivity improvement of pellet production.
Example 2
In the composition described in Example 1, the silica particles of the present invention were replaced with those described in Tables 2 and 3, and pellets were prepared in the same manner as in Example 1, and the apparatus shown in FIG. 1 was used by the following method. An optical film was prepared.

  The pellets produced in the same manner as in Example 1 were melted at 250 ° C. in a nitrogen atmosphere, and then passed through a filter with a filtration accuracy of 5 μm (manufactured by Nippon Seisen Co., Ltd., leaf disk filter) via a gear pump. The film was extruded from the rolling die 4 onto the first cooling roll 5, and formed by pressing the film between the first cooling roll 5 and the touch roll 6.

  The heat bolt was adjusted so that the gap width of the casting die 4 was 0.5 mm within 30 mm from the end in the width direction of the film and 1 mm at other locations.

  The touch roll A was used as the touch roll, and 80 ° C. water was poured as cooling water therein.

  From the position P1 at which the resin extruded from the casting die 4 contacts the first cooling roll 5 to the position P2 at the upstream end in the rotation direction of the first cooling roll 5 in the nip between the first cooling roll 5 and the touch roll 6. 1 The length L along the peripheral surface of the cooling roller 5 was set to 20 mm.

  Thereafter, the touch roll 6 is separated from the first cooling roll 5, and the temperature T of the melted part immediately before being sandwiched between the first cooling roll 5 and the touch roll 6 is measured. As a result, the temperature T is 141 ° C. Met.

  In addition, the temperature T of the melted part immediately before being squeezed by the nip between the first cooling roll 5 and the touch roll 6 is a thermometer (Anritsu Meter Co., Ltd.) at a position further 1 mm upstream from the nip upstream end P2. (Measured by HA-200E).

  The linear pressure of the touch roll 6 against the first cooling roll 5 was 14.7 N / cm.

  This film was hot-stretched in the longitudinal direction using the difference in roll peripheral speed. Heating was performed with an infrared heater, and the draw ratio was 1.5 times. Furthermore, after being introduced into a tenter and stretched 1.6 times at 160 ° C in the width direction, it was cooled to 30 ° C while relaxing 3% in the width direction, then released from the clip, the clip gripping part was cut off, and both ends of the film Was subjected to a knurling process with a width of 10 mm and a height of 5 μm, and wound on a winding core with a winding tension of 220 N / m and a taper of 40%.

  The extrusion amount and take-up speed were adjusted so that the film had a thickness of 80 μm, and the finished film width was slit and wound up so that the width of the finished film was 1430 mm.

  The winding core had an inner diameter of 152 mm, an outer diameter of 165 to 180 mm, and a length of 1550 mm.

A prepreg resin obtained by impregnating glass fibers and carbon fibers with an epoxy resin was used as the core material for the core. The surface of the core was coated with an epoxy conductive resin, the surface was polished, and the surface roughness Ra was finished to 0.3 μm. The winding length was 2500 m.
<Filterability of particles>
The resin pressure at the filter inlet was monitored over time, and evaluation was performed according to the following criteria from the time until pressure increase was observed.
○: 1000 hours or more ○ to Δ: 500 to 1000 hours Δ: 200 to 500 hours Δ to ×: 20 to 200 hours ×: Less than 20 hours <Slitability of optical film>
After attaching the 60 ° worn upper blade and the 90 ° lower blade to the hydraulic table press machine at a distance of 30 μm, each optical film was placed between both blades, and the lowering speed of the upper blade was 6 m / In minutes, 100 samples having a width of 90 cm and a length of 100 cm were continuously cut out. The cut surfaces of the cut samples were observed at 50 times using an optical microscope, and the sharpness was compared. The number of films with some defects such as burrs, cleavage, inability to cut, and generation of chips was counted, the defect rate was calculated, and the slit property was evaluated according to the following criteria.

A: The defect rate is less than 2% B: The defect rate is less than 2-5% C: The defect rate is less than 5-10% D: The defect rate is 10% or more Here, it is determined that A and B are practically acceptable levels. did.
<Haze>
According to ASTM-D1003-52, it measured using Tokyo Denshoku Industries Co., Ltd. T-2600DA.
<Dynamic friction coefficient>
The dynamic friction coefficient of the carbon film surface of each sample stored for 24 hours or more in an atmosphere of 23 ° C. and 55% RH was measured in accordance with the method described in JIS-K-7125-ISO8295 in the same atmosphere. A specimen made of stainless steel having a weight of 200 g is placed on the surface of the carbon film of each specimen, and the specimen is pulled horizontally under the conditions of a specimen moving speed of 100 mm / min and a contact area of 80 mm × 200 mm. ) And the dynamic friction coefficient (μ) was determined from the following formula.

Coefficient of dynamic friction = F (N) / weight of weight (N)
<Applicability>
A hard coat layer and a back coat layer having the following composition were applied to evaluate the coatability.

On the cellulose ester film produced above, the following hard coat layer composition is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a hard coat layer coating solution, which is applied by a micro gravure coater at 90 ° C. After drying, the coating layer is cured using an ultraviolet lamp with an illuminance of the irradiated part of 100 mW / cm ² and an irradiation amount of 0.1 J / cm ² to form a hard coat layer having a dry film thickness of 7 μm. Produced.

(Hard coat layer composition)
The following materials were stirred and mixed to obtain a hard coat layer composition.

Urethane acrylate resin: B420 (manufactured by Shin-Nakamura Chemical Co., Ltd.)
220 parts by mass Irgacure 184 (manufactured by Ciba Japan Co., Ltd.) 20 parts by mass Propylene glycol monomethyl ether 110 parts by mass Ethyl acetate 110 parts by mass Further, the following back coat layer composition was applied by an extrusion coater so as to have a wet film thickness of 10 μm. And dried at 85 ° C. and wound to provide a backcoat layer.

<Backcoat layer composition>
Acetone 54 parts by weight Methyl ethyl ketone 24 parts by weight Methanol 22 parts by weight Diacetylcellulose 0.6 part by weight Ultrafine silica 2% acetone dispersion (Aerosil 200V manufactured by Nippon Aerosil Co., Ltd.)
0.2 parts by mass (applicability evaluation)
The coating film on the hard coat layer side was observed, and the occurrence of repelling failures was counted and determined as follows.

A: 0 / 100m ²
○: 1-3 pieces / 100 m ²
Δ: 4 to 10 pieces / 100 m ²
×: 10 or more / 100 m ²

As described above, the metal-doped silica particles of the present invention have good filterability of the particles, and when contained in a film, the slit property and the dynamic friction coefficient are small, contributing to productivity improvement, and the haze which is an optical characteristic is also small. Furthermore, it is useful as a support having excellent coating properties.
Example 3
A polarizing plate using the optical film prepared in Example 2 as a polarizing plate protective film was prepared and evaluated as follows. The results are shown in Table 4.

  A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to produce a polarizer.

Next, the cellulose ester film of the present invention subjected to alkali saponification treatment on both surfaces of this polarizer was bonded using a polyvinyl alcohol adhesive and dried to prepare a polarizing plate.
<Dimensional stability: Dimensional change of polarizing plate (60 ° C., 80% RH 1000 h)>
Each of the produced polarizing plates is cut into a size of 120 mm × 120 mm, and a cross-shaped type with a sharp blade such as a razor at an interval of about 100 mm in the direction (TD direction) perpendicular to the casting direction (MD direction) on the surface of the polarizing plate. Mark.

  The polarizing plate is conditioned for 24 hours or more in an atmosphere of 23 ° C. and 55% RH, and the distance L1 between marks in the TD direction before processing is measured with a microscope.

  Next, the sample was treated for 1000 hours in an atmosphere of 60 ° C. and 80% RH using an electric thermostat.

  Next, the high-temperature and high-humidity-treated sample was conditioned again under an atmosphere of 23 ° C. and 55% RH for 24 hours, and the distance L2 between the marks in the TD direction after the treatment was measured with a microscope.

  The rate of change before and after this treatment was determined by the following equation, and the dimensional change rate in the TD direction was calculated.

Polarizer dimensional change rate (%) = (L2−L1) / L1 × 100
<Polarizing light resistance>
The total light transmittance T _{0 of the} sample before forced deterioration and the total light transmittance T ₂₀₀ after irradiation with a xenon lamp 70KLUX in an atmosphere of 23 ° C. and 55% RH for 200 hours are measured with a turbidimeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. Was measured and compared, and T ₂₀₀ / T ₀ was defined as the light resistance of the polarizing plate.

As described above, the polarizing plate is excellent in dimensional stability and light resistance using the cellulose ester film containing the metal-doped silica particles of the present invention as a polarizing plate protective film.
Example 4
<Solution cast cellulose ester film>
<Silica particle dispersion 1>
Silica particles of the present invention 11 parts by mass Ethanol 89 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Particle additive solution 1>
The particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a particle additive solution 1.

Methylene chloride 99 parts by mass Particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose esters A and B were added to a pressure dissolution tank containing a solvent while stirring.
This was heated and stirred to dissolve completely, and this was dissolved in Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate propionate (acetyl group substitution degree 1.7, propionyl group substitution degree 1.0, Mn = 86,000, Mw / Mn = 2.5) 100 parts by mass Monopet SB 6.0 parts by mass Plasticizers A, B, and C 1.0 parts by mass Particle additive solution 1 1 part by mass The above was put into an airtight container and dissolved while stirring to prepare a dope solution. Next, using an endless belt casting apparatus, the dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

  The peeled cellulose ester film was stretched 1.2 times in the width direction using a tenter while applying heat at 150 ° C. The residual solvent at the start of stretching was 15%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  As described above, a cellulose ester film 101 having a dry film thickness of 40 μm was obtained.

Plasticizer A: Triphenyl phosphate Plasticizer B: Ethylphthalyl ethyl glycolate Plasticizer C: Trimethylolpropane benzoate The cellulose ester films thus prepared were evaluated in the same manner as in Examples 2 and 3.

The particle filterability was evaluated according to the following criteria.
<Filterability of particles>
The resin pressure at the filter inlet at the time of filtering the particle additive liquid 1 was monitored over time, and evaluated from the time until the pressure increase was recognized according to the following criteria.
○: 1000 hours or more ○ to Δ: 500 to 1000 hours Δ: 200 to 500 hours Δ to ×: 20 to 200 hours ×: less than 20 hours

  As described above, the metal-doped silica particles of the present invention have good filterability of the particles, and when contained in a film, the slit property and the dynamic friction coefficient are small, contributing to productivity improvement, and the haze which is an optical characteristic is also small. Furthermore, it is useful as a support having excellent coating properties.

  As described above, the polarizing plate is excellent in dimensional stability and light resistance using the cellulose ester film containing the metal-doped silica particles of the present invention as a polarizing plate protective film.

  Further, the cellulose acetate propionate (acetyl group substitution degree 1.7, propionyl group substitution degree 1.0, Mn = 86,000, Mw / Mn = 2.5) was converted to triacetyl cellulose (acetyl group substitution degree 2. 85, Mn = 90000, Mw / Mn = 1.5), and the haze evaluation of the film produced by changing the stretching ratio in the width direction that greatly affects haze among the production conditions is shown below.

As described above, the metal-doped silica particles of the present invention have good filterability of the particles, and when incorporated in a film, the slit property and the dynamic friction coefficient are small, contributing to productivity improvement, and haze which is an optical property is also a draw ratio. It is small even if you raise it.
Example 5
<Polycycloolefin film>
To 100 parts by mass of polycycloolefin polymer (hydrogenated ring-opening copolymer of norbornene monomer, manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR 1430, glass transition temperature (Tg) = 145 ° C.) 0.2 parts by mass of phenol-based heat stabilizer pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and 0.05 parts by mass of silica particles of the present invention Were mixed and kneaded with a biaxial kneader, and a strand (rod-like molten resin) was obtained through a strand cutter to obtain a pellet.

  The pellets obtained above were dried at 110 ° C. for 4 hours using a hot air dryer in which air was circulated.

The pellets were then used in a T-die film melt extrusion machine having a resin melt kneader equipped with a 65 mmφ screw equipped with a leaf disk-shaped polymer filter (filtration accuracy 30 μm), and the surface roughness Ra = The extruded sheet-like norbornene polymer was extruded using a 350 mm wide T-shaped die having a chromium plating of 0.15 μm at a molten resin temperature of 260 ° C. and a die temperature of 260 ° C. , Temperature: 135 ° C., circumferential speed R ₁ : 10.05 m / min), then second cooling drum (diameter 250 mm, temperature: 125 ° C., circumferential speed R ₂ : 10.05 m / min), then third cooling drum (diameter 250 mm, temperature: 100 ° C., circumferential speed R _3: 9.98m / min) were sequentially close contact with transported, length 300 meters, film Polycycloolefin film 40μm was extruded. The obtained long polycycloolefin film was wound up in a roll shape.

  Moreover, content of the volatile component of this polycycloolefin film was 0.01 mass% or less, and the saturated water absorption was 0.01 mass% or less.

  The polycycloolefin film thus produced was evaluated in the same manner as in Example 2.

As described above, the metal-doped silica particles of the present invention have good filterability of the particles, and when contained in a film, the slit property and the dynamic friction coefficient are small, contributing to productivity improvement, and the haze which is an optical characteristic is also small. Furthermore, it is useful as a support having excellent coating properties.
Example 6
A polarizing plate using the optical film prepared in Example 5 as a polarizing plate protective film was prepared and evaluated as follows.

  A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to produce a polarizer.

  Next, using the acrylic adhesive on both surfaces of this polarizer, the produced optical film was corona-treated, and then bonded.

As described above, the polarizing plate is excellent in dimensional stability and light resistance using the polycycloolefin film containing the metal-doped silica particles of the present invention as a polarizing plate protective film.
Example 7
<Solution cast acrylic polymer-containing film>
The following acrylic polymer A1 was produced by a known method.
A1: Poly (MMA-MA) mass ratio 98: 2 Mw 70000
MMA; Methyl methacrylate MA; Methyl acrylate <Preparation of acrylic polymer-containing film 1>
(Dope solution composition)
Acrylic resin A1 70 parts by mass CAP482-20 (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000 manufactured by Eastman Chemical Co., Ltd.)
30 parts by mass Methylene chloride 300 parts by mass Ethanol 40 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

(Formation of acrylic polymer-containing film)
The produced dope solution was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m.

  The peeled acrylic resin web was evaporated at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while being stretched 1.1 times in the width direction by a tenter. At this time, the residual solvent amount when starting stretching with a tenter was 10%.

  After stretching with a tenter and relaxing at 130 ° C for 5 minutes, drying was completed while transporting the drying zone at 120 ° C and 130 ° C with a number of rolls, slitting to a width of 1.5 m, and 10 mm wide at both ends of the film. A knurling process having a thickness of 5 μm was performed, and the film was wound around a 6-inch inner diameter core with an initial tension of 220 N / m and a final tension of 110 N / m to obtain an acrylic polymer-containing film 1.

  The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times.

  The residual solvent amount of the acrylic polymer-containing film was 0.1%, the film thickness was 60 μm, and the winding length was 4000 m.

  The acrylic polymer-containing film thus produced was evaluated in the same manner as in Example 2.

As described above, the metal-doped silica particles of the present invention have good filterability of the particles, and when contained in a film, the slit property and the dynamic friction coefficient are small, contributing to productivity improvement, and the haze which is an optical characteristic is also small. Furthermore, it is useful as a support having excellent coating properties.
Example 8
A polarizing plate using the acrylic polymer-containing film prepared in Example 7 as a polarizing plate protective film was prepared and evaluated as follows.

  A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to produce a polarizer.

  Next, using an acrylic adhesive on both surfaces of this polarizer, the produced acrylic polymer-containing film was subjected to corona treatment and then bonded.

  As described above, the polarizing plate is excellent in dimensional stability and light resistance using the acrylic polymer-containing film containing the metal-doped silica particles of the present invention as a polarizing plate protective film.

Claims (3)

  An optical film having a haze value in the range of 0.0 to 0.5, comprising silica particles doped with at least one metal element.   The optical film according to claim 1, wherein the metal element is selected from aluminum, titanium, zinc, zirconium, and magnesium.   A polarizing plate using the optical film according to claim 1 or 2.