WO2013108778A1

WO2013108778A1 - Optical film, manufacturing method for optical film, polarizing plate, and liquid crystal display device

Info

Publication number: WO2013108778A1
Application number: PCT/JP2013/050655
Authority: WO
Inventors: 齋藤　浩一
Original assignee: コニカミノルタアドバンストレイヤー株式会社
Priority date: 2012-01-17
Filing date: 2013-01-16
Publication date: 2013-07-25
Also published as: JPWO2013108778A1

Abstract

　Provided are an optical film which is strong and which does not exhibit yellow coloration even if manufactured by means of melt casting, and a manufacturing method for the optical film. Also provided are a liquid crystal display device which does not become yellow during white display time, and which has excellent viewing angle properties even when kept in a hot and humid environment, and a polarizing plate which is used in the liquid crystal display device.　The optical film according to the present invention contains an acrylic resin and copper ions, and is characterised in that the amount of copper ions included is within the range of 20-100 mass% relative to the optical film.

Description

Optical film, optical film manufacturing method, polarizing plate, and liquid crystal display device

The present invention relates to an optical film, a manufacturing method thereof, a polarizing plate and a liquid crystal display device, and more particularly to an optical film which is suitably used for an IPS liquid crystal display device and has high strength and improved coloring, and a manufacturing method thereof.

Demand for liquid crystal display devices is expanding for applications such as liquid crystal televisions and personal computer liquid crystal displays. In general, a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof. The element (also referred to as a polarizing film or a polarizing film) is sandwiched between two optical films (also referred to as a polarizing plate protective film). As this polarizing plate protective film, a cellulose triacetate film is usually used.

Such a liquid crystal display device is required to have a wide viewing angle, and attention is paid to an IPS system in which a hue change due to the viewing angle is small. In the case of this IPS system, when no voltage is applied, the liquid crystal is aligned parallel to the screen, and when the voltage is applied, the liquid crystal rotates in a plane parallel to the screen, so that the change in phase difference between the front and the diagonal is small. If there is a phase difference (Rt) in the optical film between the polarizer and the liquid crystal cell, the optical film changes its color in front and obliquely due to the phase difference of the optical film, so the optical film is required to have no phase difference. ing.

In addition, when the liquid crystal display device is stored under high temperature and high humidity, a phase difference occurs in the optical film, and the viewing angle changes in a direction that deteriorates. For this reason, even when stored under high temperature and high humidity, there is a demand for a phase difference in the optical film that does not deteriorate the viewing angle of the liquid crystal display device.

On the other hand, due to recent technological advances, the enlargement of liquid crystal display devices has accelerated, and the applications of liquid crystal display devices have diversified. For example, it can be used as a large display installed in a street or a store, or used as an advertising display in a public place using a display device called digital signage.

In such applications, since it is assumed to be used outdoors, deterioration due to moisture absorption of the polarizing film becomes a problem, and the polarizing plate protective film is required to have higher moisture resistance. However, it has been difficult to obtain sufficient moisture resistance with cellulose ester films such as cellulose triacetate films that have been used in the past, and there has been a problem that the optical effect increases when the film thickness is increased in order to obtain moisture resistance. . Furthermore, in recent years, there has been a demand for thinning of the apparatus, so that the thickness of the polarizing plate itself has also become a problem.

On the other hand, polymethyl methacrylate (hereinafter abbreviated as “PMMA”), which is a representative of acrylic resin, as an optical film material having low hygroscopicity, exhibits excellent transparency and dimensional stability in addition to low hygroscopicity. It was used suitably for the film.

However, as described above, the liquid crystal display device is increased in size, and the width of the original film is wide and the winding length is required to be long. Therefore, although the film original is wide, workability is poor due to insufficient improvement in brittleness, and handling properties are not sufficient for producing an optical film used for a large liquid crystal display device.

As a technique for improving moisture resistance and processability, a technique for producing a mixed composition of a polymer having a cellulose resin and an acrylic resin by an extrusion molding method has also been proposed (see Patent Document 1). However, when various two resins are mixed by the extrusion method proposed in this method and film formation is performed by melt casting, it is estimated that the compatibility is not sufficient depending on the mixed resin components. Occurs, the haze is high, the transparency is insufficient, and when used as an optical film, there is a problem that the contrast of the image is lowered. In addition, when the optical film was stored for a long time, a tendency to yellow was observed.

In order to improve the compatibility between the cellulose resin and the acrylic resin and to provide a highly transparent optical film, a technique of adding an acrylic resin having an amide group has been proposed (see Patent Document 2). However, an acrylic resin having an amide group must be kept in a molten state at a high temperature in melt casting, and is colored yellow. In addition, an optical film produced by adding an acrylic resin having an amide group to a cellulose derivative has a more intense yellow coloring in the melt casting than when an acrylic resin and a cellulose resin having no amide group are used. Therefore, there has been a problem that the image quality of the liquid crystal display device using this optical film is deteriorated.

Also, in recent years, with the thinning of liquid crystal display devices, there has been a demand for thinner optical films. For this reason, it has been desired to further improve the film strength.

JP 2008-88417 A Japanese Patent Application Laid-Open No. 2011-248094

The present invention has been made in view of the above-described problems and circumstances, and its solution is to provide an optical film having high strength and not yellow-colored even when manufactured by melt casting and a method for manufacturing the same. It is. Another object of the present invention is to provide a liquid crystal display device that does not turn yellow during white display and has good viewing angle characteristics even when stored in a high-temperature and high-humidity environment, and a polarizing plate used in the liquid crystal display device.

In order to solve the above problems, the present inventor added copper ions in the range of 20 to 100 mass ppm to the optical film containing the acrylic resin in the process of examining the cause of the above problems, etc. The inventors have found that the viewing angle characteristics when stored under high strength, coloring, and high temperature and high humidity are improved, and the present invention has been achieved.

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

1. An optical film comprising an acrylic resin and copper ions, wherein the content of the copper ions is in the range of 20 to 100 ppm by mass with respect to the optical film.

2. 2. The optical film according to item 1, wherein the acrylic resin has an amide group.

3. The optical film according to

item

1 or 2, which contains a cellulose resin.

4. 4. The optical film according to any one of items 1 to 3, wherein the film thickness is in the range of 10 to 45 μm.

5. It is a manufacturing method of the optical film which manufactures the optical film as described in any one of Claim 1 to 4, Comprising: The said copper ion is added as copper gluconate or acetylacetonate copper, It is characterized by the above-mentioned. A method for producing an optical film.

6. An optical film manufacturing method for manufacturing the optical film according to any one of items 1 to 4, wherein the optical film is formed by a melt casting method.

7. A polarizing plate comprising the optical film according to any one of items 1 to 4.

8. The optical film according to any one of items 1 to 4, a polarizer, and a counter film are provided in this order, the counter film contains a cellulose resin, and the thickness of the counter film is 20 to 60 μm. A polarizing plate characterized by being in the range of.

9. A liquid crystal display device comprising the polarizing plate according to item 7 or 8.

The above-mentioned means of the present invention can provide an optical film having high strength and not yellow-colored even when manufactured by melt casting and a method for manufacturing the same. In addition, it is possible to provide a liquid crystal display device having favorable viewing angle characteristics even when stored in a high temperature and high humidity environment and a polarizing plate used for the liquid crystal display device, even when white display is not performed.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

It is considered that when the acrylic resin is heated at a high temperature, it decomposes to form a yellow colored substance by forming a chelate with a functional group of the acrylic resin. In particular, when the acrylic resin has an amide group, since the bond between the copper ion and the amide group is strong, it is considered that the effect of preventing coloration by the copper ion is even greater. Further, since the divalent copper ions are bluish, it is considered that canceling out the yellow coloring caused by the decomposition of the resin is also advantageous. Moreover, it is thought that the strength is improved by bonding the copper ions and the acrylic resin, and the brittleness of the acrylic resin can be improved.

Schematic flow sheet showing one embodiment of a production apparatus for carrying out the method for producing an optical film according to the present invention 1 is an enlarged flow sheet of the main part of the manufacturing apparatus of FIG. External view of main parts of casting die Cross section of the main part of the casting die Sectional drawing of 1st Embodiment of a pinching rotary body (it is also called a touch roller). Sectional drawing in the plane perpendicular | vertical to the rotating shaft of 2nd Embodiment of a pinching rotary body Sectional drawing in the plane containing the rotating shaft of 2nd Embodiment of a pinching rotary body

The optical film of the present invention is characterized by containing an acrylic resin and containing copper ions in a range of 20 to 100 ppm by mass with respect to the optical film. This feature is a technical feature common to the inventions according to claims 1 to 9.

As an embodiment of the present invention, it is preferable that the acrylic resin has an amide group from the viewpoint of manifesting the effects of the present invention. Moreover, it is preferable to contain a cellulose resin because the effects of improving the strength of the optical film and improving the viewing angle characteristics can be obtained.

Furthermore, in the optical film of the present invention, the film thickness is preferably in the range of 10 to 45 μm. Thereby, the effect of preventing coloring and improving the strength is obtained.

As a method for producing the optical film of the present invention, copper ions are added as copper gluconate or acetylacetonate copper, since the acrylic resin and copper ions are uniformly mixed, and the anti-coloring effect is improved. preferable.

In addition, when the optical film is produced by the melt casting method, since it is exposed to high heat in the production process, the effect of the anti-coloring effect of the present invention becomes more remarkable. The film is preferably formed by the method.

The optical film of the present invention can be suitably included in a polarizing plate and a liquid crystal display device using the polarizing plate. Further, a polarizing plate having an optical film, a polarizer and a counter film in this order, wherein the counter film contains a cellulose resin and has a thickness in the range of 20 to 60 μm, has particularly high strength and warpage. It is preferable because it is difficult.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<Optical film>
In the present invention, the “optical film” is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and more specifically, a polarizing plate protective film and a retardation film for a liquid crystal display device. , An antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for expanding the viewing angle, and the like.

The optical film of the present invention is preferably used for a polarizing plate protective film (including a polarizing plate protective film provided with a functional layer). The optical film used as the polarizing plate protective film preferably has a retardation value close to zero.

(Measurement method of retardation value)
Retardation Ro and Rt are calculated | required by a following formula.

Formula _{(i) Ro = (n x} -n y) × d
Formula (ii) Rt = ((n _x + n _y ) / 2−n _z ) × d
(Wherein, n _x is a refractive index in a slow axis direction in the film plane, n _y is the fast axis direction of the refractive index in the film plane, n _z is the thickness direction of the refractive index (refractive index of the film 23 (Measured at a wavelength of 590 nm in an environment of 55 ° C. and 55% RH), d represents the thickness (nm) of the film.)
The refractive index of the optical film is an Abbe refractometer (4T), the thickness of the film is a commercially available micrometer, and the retardation value is an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments) Etc.) can be used for measurement.

The optical film of the present invention contains an acrylic resin and copper ions.

The film thickness of the optical film of the present invention is preferably in the range of 10 to 45 μm. If it is 10 microns or more, it is easy to tear, and it is easy to handle. If it is 45 μm or less, yellow coloring due to long-term storage is not noticeable, and the manufacturing cost can be reduced. This is because it meets the demand.

<Acrylic resin>
The acrylic resin used in the present invention includes a methacrylic resin. Although it does not restrict | limit especially as resin, It is preferable that it is a copolymer which uses methyl methacrylate as one of the copolymerization components.

Further, the acrylic resin is preferably an acrylic resin having an amide group because the retardation value of the optical film is small and the strength is high.

<Acrylic resin having an amide group>
The optical film of the present invention preferably contains an acrylic resin having an amide group. Since the acrylic resin has an amide group, it has excellent affinity with the cellulose resin and excellent compatibility with the cellulose resin, so that haze can be suppressed low and transparency is also good.

The acrylic resin having an amide group is preferably synthesized by copolymerization of a copolymer component having an amide group and an acrylic copolymer component.

Examples of copolymer components having amide groups include N-vinylpyrrolidone (VP), N-vinyl-2-methylpyrrolidone, acryloylmorpholine (ACMO), acryloyl-2-methylmorpholine, dimethylacrylamide (DMAA), vinylacetamide, etc. In particular, N-vinylpyrrolidone and acryloylmorpholine are preferable.

The copolymerization ratio of the acrylic resin having an amide group is preferably such that the copolymer component having an amide structure is in the range of 5 to 50% by mass of the total copolymer components constituting the polymer. % Is more preferable.

In particular, the number average molecular weight (Mn) of the acrylic resin having an amide group is in the range of 60,000 to 400,000 from the viewpoint of improving brittleness as an optical film and improving transparency when it is compatible with a cellulose resin. The inner level is preferable, and the range of 80,000 to 300,000 is more preferable. If the number average molecular weight (Mn) is 60,000 or more, high strength is obtained, and if it is 400,000 or less, high transparency is obtained.

Molecular weight can be measured by the same method as for cellulose resin.

The acrylic resin having an amide group is preferably used in the range of 50 to 100% by mass in the optical film, and more preferably in the range of 60 to 80% by mass. When the addition amount is 60% by mass or more, the effect of the amide group can be exerted and the strength can be improved. When the addition amount is 80% by mass or less when mixed with the cellulose resin, when used in a liquid crystal display device. Viewing angle characteristics are further improved.

The acrylic resin having an amide group may have a third copolymer component in addition to the methyl methacrylate and the copolymer component having an amide group. The third copolymer component may be an acrylic copolymer component or a copolymer component other than an acrylic copolymer component.

Examples of the acrylic copolymer component include α, β-nondeoxyalkylene such as alkyl methacrylate having 2 to 18 alkyl atoms, alkyl acrylate having 1 to 18 carbon atoms, acrylic acid, and methacrylic acid. Examples thereof include α, β-unsaturated nitriles such as saturated acid, acrylonitrile and methacrylonitrile, and these can be used alone or in combination of two or more monomers. Among these, acrylic acid, methyl acrylate (MA), ethyl acrylate, propyl acrylate, butyl acrylate, methacrylic acid, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate (HEMA), etc. Is preferably used. Of these, methyl methacrylate, methyl acrylate, and 2-hydroxyethyl methacrylate are particularly preferable.

Examples of the copolymer component other than acrylic include unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, maleic anhydride, maleimide, N -Substituted maleimide, vinyl acetate and the like are mentioned, and among these, styrene and vinyl acetate are preferably used.

The weight average molecular weight of the acrylic resin 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 manufactured by Showa Denko KK)
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 are used. The 13 samples are preferably used at approximately equal intervals.

The production method of the acrylic resin in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used.

The polymerization temperature may be within a range of 30 to 100 ° C. for suspension or emulsion polymerization, and within a range of 80 to 160 ° C. for bulk or solution polymerization. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

<Cellulose resin>
In addition to the acrylic resin having an amide group, the optical film of the present invention preferably contains a cellulose resin because the strength of the film is further improved.

Examples of the cellulose resin include cellulose ester and alkoxy cellulose. Examples of the alkoxy cellulose include ethyl cellulose (sold under the trade name Etcel from Nisshin Chemical). Among them, cellulose ester is preferable as the cellulose resin, and the total substitution degree (T) of acyl group is 2.0 to 3.0, particularly from the viewpoint of transparency when improved in brittleness or compatible with acrylic resin. In this range, cellulose esters in which the substitution degree of the acyl group having 3 to 7 carbon atoms is in the range of 1.2 to 3.0 are preferable. That is, the cellulose resin according to the present invention is preferably a cellulose ester substituted with an acyl group having 3 to 7 carbon atoms. As specific acyl groups, propionyl, butyryl and the like are preferably used, and a propionyl group is particularly preferable. Used.

When the total substitution degree of the acyl group of the cellulose ester is 2.0 or more, that is, when the residual degree of the hydroxy group at the 2,3,6-position of the cellulose ester molecule is 1.0 or less, an acrylic type Resin and cellulose ester exhibit high compatibility and are highly transparent when used as an optical film.

Further, when the total substitution degree of the acyl group is 2.0 or more and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 or more, higher compatibility is obtained and the strength is excellent. . For example, the total substitution degree of the acyl group is 2.0 or more, the substitution degree of the acyl group having 2 carbon atoms (ie, acetyl group) is low, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 or more. In this case, the compatibility and strength are further improved.

It is preferable that the total substitution degree of the acyl group having a carbon number other than 3 to 7 in the cellulose ester, that is, the acetyl group or the acyl group having 8 or more carbon atoms is 1.3 or less.

Further, the total substitution degree (T) of the acyl group of the cellulose ester is more preferably in the range of 2.5 to 3.0.

In the present invention, the acyl group may be an aliphatic acyl group or an aromatic acyl group. In the case of an aliphatic acyl group, it may be linear or branched and may further have a substituent. The number of carbon atoms of the acyl group in the present invention includes an acyl group substituent.

When the cellulose ester has an aromatic acyl group as a substituent, the number of substituents substituted on the aromatic ring is preferably 0 to 5. Also in this case, it is necessary to pay attention so that the substitution degree of the acyl group having 3 to 7 carbon atoms including the substituent is in the range of 1.2 to 3.0.

For example, since the benzoyl group has 7 carbon atoms, when it has a substituent containing carbon, the benzoyl group has 8 or more carbon atoms and is not included in the acyl group having 3 to 7 carbon atoms. Become.

Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

The cellulose ester as described above preferably has a structure having at least one aliphatic acyl group having 3 to 7 carbon atoms.

The cellulose resin according to the present invention is preferably at least one selected from cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, and cellulose butyrate. Among these, particularly preferred cellulose resins are cellulose acetate propionate and cellulose propionate.

The portion not substituted with an acyl group is usually present as a hydroxy group. These can be synthesized by known methods.

Incidentally, the substitution degree of the acetyl group and the substitution degree of other acyl groups were determined by the method prescribed in ASTM-D817-96.

The weight average molecular weight (Mw) of the cellulose resin according to the present invention is preferably in the range of 75,000 to 300,000, particularly in the range of 100,000 to 250,000, from the viewpoint of improving compatibility with acrylic resins and improving brittleness. Is more preferable, and those within the range of 150,000 to 250,000 are particularly preferable.

When the important average molecular weight (Mw) of the cellulose resin is less than 75,000, the effect of improving heat resistance and brittleness may not be sufficient, and the effect of the present invention may not be obtained. In the present invention, two or more kinds of cellulose resins can be mixed and used.

In the optical film of the present invention, the mass ratio value of the acrylic resin and the cellulose resin is preferably in the range of 50:50 to 94: 6 and in a compatible state, more preferably 60:40. Within the range of 90:10.

When the value of the mass ratio between the acrylic resin and the cellulose resin is 94: 6 or less, an improvement in strength and an improvement in viewing angle characteristics are observed with the cellulose resin, and the value of the mass ratio is 50:50 or more. When there are many acrylic resins, moisture resistance is excellent.

In the optical film of the present invention, it is preferable that an acrylic resin and a cellulose resin are contained in a compatible state. The physical properties and quality required for an optical film are achieved by supplementing each other by dissolving different resins.

Whether the acrylic resin and the cellulose resin are in a compatible state can be determined, for example, based on the glass transition temperature Tg.

For example, when the glass transition temperatures of the two resins are different, when the two resins are mixed, there are two or more glass transition temperatures of the mixture because there is a glass transition temperature of each resin. When they are compatible, the glass transition temperature specific to each resin disappears and becomes one glass transition temperature, which becomes the glass transition temperature of the compatible resin.

The glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a heating rate of 20 ° C./min. The point glass transition temperature (Tmg).

The acrylic resin and the cellulose resin are each preferably an amorphous resin, and either one may be a crystalline polymer or a partially crystalline polymer. The resin and the cellulose resin are preferably compatible with each other to become an amorphous resin.

After the weight average molecular weight (Mw) of the acrylic resin in the optical film of the present invention, the weight average molecular weight (Mw) of the cellulose resin, and the degree of substitution are separated using the difference in solubility in the solvent of both resins. , Obtained by measuring each. When fractionating the resin, it is possible to extract and separate the soluble resin by adding a compatible resin in a solvent that is soluble only in either one. At this time, heating operation or reflux is performed. May be. A combination of these solvents may be combined in two or more steps to separate the resin.

The dissolved resin and the resin remaining as an insoluble material are filtered off, and the solution containing the extract can be separated by an operation of evaporating the solvent and drying. These fractionated resins can be identified by general structural analysis of polymers. When the optical film of the present invention contains a resin other than an acrylic resin or a cellulose resin, it can be separated by the same method.

If the weight average molecular weights (Mw) of the compatible resins are different, the high molecular weight substances are eluted earlier by gel permeation chromatography (GPC), and the lower molecular weight substances are eluted after a longer time. Therefore, it can be easily fractionated and the molecular weight can be measured.

In addition, the molecular weight of the compatible resin is measured by GPC, and at the same time, the resin solution eluted every time is separated, the solvent is distilled off, and the dried resin is different by quantitatively analyzing the structure. By detecting the resin composition for each molecular weight fraction, it is possible to identify each compatible resin. By measuring the molecular weight distribution of each of the resins separated in advance based on the difference in solubility in a solvent by GPC, it is possible to detect each of the compatible resins.

The total mass of the acrylic resin and the cellulose resin in the optical film of the present invention is preferably 55% by mass or more of the optical film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. .

<Copper ion>
The copper ion according to the present invention is preferable because a divalent copper ion greatly improves the film strength. Copper ions are preferably added to the resin as an organic copper compound in order to be uniformly mixed with the resin. Specifically, copper acetylacetonate (II), copper gluconate (II), glycinate copper (II), copper (II) bisisobutyrate, copper (II) trifluoroacetylacetonate, Pigment Blue 15, etc. are preferable, and the ligand is preferably a complex or salt having a β-diketone structure or a carboxy group. Among them, it is particularly preferable that acetylacetonate copper (II) or gluconate copper (II) is added.

The copper (II) acetylacetonate and copper (II) gluconate are suitable when the organic copper compound is added to the acrylic resin when the bond stability between the copper and the organic group is not too high and appropriate. Since copper ions can bind to the acrylic resin, it is considered that the effect of the present invention is more remarkably exhibited.

The content of copper ions in the optical film is in the range of 20 to 100 ppm by mass. If the copper ion content is 20 mass ppm or more, a large strength can be obtained, and yellow coloration is not observed even if it is used for a long time at a high temperature. When the image is visually observed, the bluish color is suppressed to such an extent that it cannot be confirmed.

On the other hand, a film having a thickness of 20 to 40 μm containing 300 to 600 ppm by mass of copper phthalocyanine in an acrylic resin is known, but since it is strong in blue, it cannot be applied to an optical film used for an image display device or the like.

<Additives>
In the optical film of the present invention, the following additives are preferably added for the purpose of reducing breakage failure in the production process. Three types of additives: (1) carbon radical scavenger, (2) primary antioxidant having hydrogen radical donating ability for peroxy radical, and (3) secondary antioxidant having a reducing action on peroxide. Combined.

(1) Carbon radical scavenger The optical film of the present invention preferably contains at least one carbon radical scavenger.

The “carbon radical scavenger” has a group (for example, an unsaturated group such as a double bond or a triple bond) that allows a carbon radical to rapidly undergo an addition reaction, and a subsequent reaction such as polymerization occurs after the addition of the carbon radical. It is a compound that gives no stable product.

Examples of the carbon radical scavenger include compounds having a radical polymerization inhibiting ability such as a group (an unsaturated group such as a (meth) acryloyl group or an aryl group) that reacts quickly with a carbon radical in the molecule, and a phenolic or lactone based compound. The compound represented by the following general formula (1) or general formula (2) is particularly preferable.

In the general formula (1), R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, particularly preferably a hydrogen atom or a methyl group. .

R ₁₂ and R ₁₃ each independently represents an alkyl group having 1 to 8 carbon atoms, and may be linear or have a branched structure or a ring structure.

R ₁₂ and R ₁₃ are preferably a structure represented by “* —C (CH ₃ ) ₂ —R ′” containing a quaternary carbon (* represents a connecting site to an aromatic ring, and R ′ represents a carbon number of 1 Represents an alkyl group of ˜5).

R ₁₂ is more preferably a tert-butyl group, a tert-amyl group or a tert-octyl group. R ₁₃ is more preferably a tert-butyl group or a tert-amyl group. As the compound represented by the general formula (1), commercially available products include “Sumilizer GM, Sumilizer GS” (both trade names, manufactured by Sumitomo Chemical Co., Ltd.) and the like.

Specific examples (I-1 to I-18) of the compound represented by the general formula (1) are exemplified below, but the present invention is not limited thereto.

In the general formula (2), R ₂₂ to R ₂₅ each independently represent a hydrogen atom or a substituent, and the substituent represented by R ₂₂ to R ₂₅ is not particularly limited. (For example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group) Etc.), aryl groups (eg phenyl group, naphthyl group etc.), acylamino groups (eg acetylamino group, benzoylamino group etc.), alkylthio groups (eg methylthio group, ethylthio group etc.), arylthio groups (eg phenylthio) Group, naphthylthio group, etc.), alkenyl group (for example, vinyl group, 2-propenyl group, 3-butyl group) Nyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom) , Iodine atoms, etc.), alkynyl groups (eg, propargyl group, etc.), heterocyclic groups (eg, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.), alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group, etc.) ), Arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.), phosphono group, acyl group (eg, Acetyl group, pivaloyl group, benzoyl group, etc.), cal Moyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group) , Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group Group), sulfonamide group (eg, methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy group (eg, Toxyl group, ethoxy group, propoxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), heterocyclic oxy group, siloxy group, acyloxy group (eg, acetyloxy group, benzoyloxy group, etc.), sulfone Acid group, sulfonic acid salt, aminocarbonyloxy group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino Group (eg, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (eg, methylureido group, ethylureido group, pentylureido group, cyclohexyl) Ureido group, octylureido , Dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino group (eg, methoxycarbonylamino group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, Ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group, etc.), heterocyclic thio group, thioureido group, carboxy group, carboxylic acid salt, hydroxy group, mercapto group, nitro group, etc. Is mentioned. These substituents may be further substituted with the same substituent.

In the general formula (2), R ₂₆ represents a hydrogen atom or a substituent, and examples of the substituent represented by R ₂₆ include the same groups as the substituents represented by R ₂₂ to R _25. .

In the general formula (2), n represents 1 or 2.

In the general formula (2), when n is 1, R ₂₁ represents a substituent, and when n is 2, R ₂₁ represents a divalent linking group. When R ₂₁ represents a substituent, examples of the substituent include the same groups as the substituents represented by R ₂₂ to R ₂₅ .

When R ₂₁ represents a divalent linking group, examples of the divalent linking group include an alkylene group that may have a substituent, an arylene group that may have a substituent, an oxygen atom, a nitrogen atom, and a sulfur atom. Or a combination of these linking groups.

In the general formula (2), n is preferably 1.

Next, specific examples of the compound represented by the general formula (2) in the present invention are shown, but the present invention is not limited to the following specific examples.

The carbon radical scavengers can be used singly or in combination of two or more, and the amount of the carbon radical scavenger is appropriately selected within a range that does not impair the object of the present invention. Resin (acrylic resin and cellulose resin) 100 Usually in the range of 0.001 to 10.0 parts by weight, preferably in the range of 0.01 to 5.0 parts by weight, more preferably in the range of 0.1 to 1.0 parts by weight with respect to parts by weight. Is within.

(2) Primary antioxidant The optical film of the present invention preferably contains at least one primary antioxidant having hydrogen radical donating ability for peroxy radicals.

In the present invention, the “primary antioxidant having the ability to donate hydrogen radicals to peroxy radicals” means that the molecule has at least one hydrogen atom that can be quickly extracted by peroxy radicals, and peroxides from peroxy radicals. The compound to be produced is preferably an aromatic compound substituted with a hydroxy group or a primary or secondary amino group or a heterocyclic compound having a sterically hindered group, and more preferably an alkyl group at the ortho position. A phenolic compound or a hindered amine compound.

(Phenolic compounds)
Phenol compounds preferably used in the present invention include 2,6-dialkylphenol derivative compounds such as those described in US Pat. No. 4,839,405, columns 12-14. Such a compound includes a compound represented by the following general formula (3).

In the formula, R ₃₁ to R ₃₆ each represents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom (eg, fluorine atom, chlorine atom), an alkyl group (eg, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group), A cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), an aralkyl group (eg, benzyl group, 2-phenethyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), alkoxy Groups (eg methoxy, ethoxy, isopropoxy, butoxy), aryloxy (eg phenoxy), cyano, acylamino (eg acetylamino, propionylamino), alkylthio (eg methylthio) Group, ethylthio group, butylthio group, etc.), aryl O group (for example, phenylthio group), sulfonylamino group (for example, methanesulfonylamino group, benzenesulfonylamino group, etc.), ureido group (for example, 3-methylureido group, 3,3-dimethylureido group, 1,3-dimethylureido) Group), sulfamoylamino group (dimethylsulfamoylamino group etc.), carbamoyl group (eg methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group etc.), sulfamoyl group (eg ethylsulfamoyl group, dimethylsulfamoyl group) Moyl group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group etc.), aryloxycarbonyl group (eg phenoxycarbonyl group etc.), sulfonyl group (eg methanesulfonyl group, butanesulfonyl group, phenylsulfonyl group) Group), acyl group (eg, acetyl group, propanoyl group, butyroyl group, etc.), amino group (methylamino group, ethylamino group, dimethylamino group, etc.), cyano group, hydroxy group, nitro group, nitroso group, amine oxide Groups (for example, pyridine-oxide groups), imide groups (for example, phthalimide groups), disulfide groups (for example, benzene disulfide groups, benzothiazolyl-2-disulfide groups), carboxy groups, sulfo groups, heterocyclic groups (for example, pyrrole groups, Pyrrolidyl group, pyrazolyl group, imidazolyl group, pyridyl group, benzimidazolyl group, benzthiazolyl group, benzoxazolyl group, etc.). These substituents may be further substituted.

Further, a compound in which R ₃₁ is a hydrogen atom and R ₃₂ and R ₃₆ are t-butyl groups is preferable. Specific examples of phenolic compounds include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, n-octadecyl 3- (3,5-di-t-butyl-4 -Hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5 -Di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl β (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n- Octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenyl acetate, 2- (n-octadecyl) Thio) ethyl 3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxy Ethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4- Droxy-phenyl) propionate, 2- (n-octadecylthio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene 3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- ( 2-stearoyloxyethylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-tert-butyl-4-hydroxy Phenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxypheny ) Propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-ln-octadecanoate-2,3-bis- (3,5 -Di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 3,9-bis- { 2- [3- (3-tert-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,1,1-trimethylolethane-tris- [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate], sorbitol hexa- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-tbutyl-4-hydroxyphenyl) propionate 2-stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ′, 5′-di-t-butyl- 4-hydroxyphenyl) propionate], pentaerythritol tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate) Be turned. The phenol compound of the above type is commercially available, for example, from BASF Japan Ltd. under the trade names “Irganox 1076” and “Irganox 1010”.

The above-mentioned phenol compounds can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within the range not impairing the object of the present invention, but 100 parts by mass of resin (acrylic resin and cellulose resin) Is usually within the range of 0.001 to 10.0 parts by mass, preferably within the range of 0.05 to 5.0 parts by mass, and more preferably within the range of 0.1 to 2.0 parts by mass. is there.

(Hindered amine compounds)
The hindered amine compound preferably used in the present invention is preferably a hindered amine compound represented by the following general formula (4).

In the formula, R ₄₁ to R ₄₇ each represents a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). R ₄₄ is preferably a hydrogen atom and a methyl group, R ₄₇ is a hydrogen atom, and R ₄₂ , R ₄₃ , R ₄₅ and R ₄₆ are preferably a methyl group. Specific examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2,2) , 6,6-Tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6- Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6,6- Tramethyl-4-piperidyl) 2,2-bis (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4- Piperidyl) decanedioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1- [ 2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2, 6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

Further, it may be a polymer type compound. Specific examples include N, N ′, N ″, N ″ ′-tetrakis- [4,6-bis- [butyl- (N-methyl-2,2,6, 6-tetramethylpiperidin-4-yl) amino] -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine-N, N′-bis ( 2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, di Polycondensate of butylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3 -Tetramethylbutyl) amino-1,3,5-to Azine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], Between 1,6-hexanediamine-N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5-triazine Polycondensate, poly [(6-morpholino-s-triazine-2,4-diyl) [(2,2,6,6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6 , 6-tetramethyl-4-piperidyl) imino]], etc., high molecular weight HALS in which a plurality of piperidine rings are bonded via a triazine skeleton; dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl- 1-piperidine Polymer with tanol, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethyl) (Ethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, and the like, and the like include, but are not limited to, compounds in which a piperidine ring is bonded via an ester bond. It is not a thing.

Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1, 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2 , 2,6,6-tetramethyl-4-piperidyl) imino}], a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, etc. Those having a molecular weight (Mn) in the range of 2,000 to 5,000 are preferred.

The hindered amine compound of the above type is commercially available, for example, from BASF Japan Co., Ltd. under the trade names “Tinvin 144” and “Tinvin 770”, and from ADEKA Co., Ltd. under the name “Adeka Stub LA-52”.

The above-mentioned hindered amine compounds can be used alone or in combination of two or more, and the blending amount is appropriately selected within the range not impairing the object of the present invention, but 100 parts by mass of resin (acrylic resin and cellulose resin) Is usually within the range of 0.001 to 10.0 parts by mass, preferably within the range of 0.05 to 5.0 parts by mass, and more preferably within the range of 0.1 to 2.0 parts by mass. is there.

(3) Secondary antioxidant The optical film of the present invention preferably contains at least one secondary antioxidant having a reducing action on peroxide.

In the present invention, the “secondary antioxidant having a reducing action on peroxide” is a reducing compound that rapidly reduces peroxide to convert it into a hydroxy group.

As the secondary antioxidant having a reducing ability for peroxide, a phosphorus compound or a sulfur compound is preferable.

(Phosphorus compounds)
The phosphorus compound preferably used in the present invention is preferably a phosphorus compound selected from the group consisting of phosphite, phosphonite, phosphinite, or tertiary phosphane. A compound having a partial structure represented by the following general formulas (5-1), (5-2), (5-3), (5-4), and (C-5) in the molecule is preferable.

In the formula, Ph ₁ and Ph ′ ₁ represent a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). More preferably, Ph ₁ and Ph ′ ₁ represent a phenylene group, and the hydrogen atom of the phenylene group is a phenyl group, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 to 12 carbon atoms. And may be substituted with an alkylcycloalkyl group or an aralkyl group having 7 to 12 carbon atoms. Ph ₁ and Ph ′ ₁ may be the same as or different from each other. X represents a single bond, a sulfur atom or a —CHR— group. R represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. These may be substituted with a substituent having the same meaning as the substituent represented by R ₃₁ to R ₃₆ in the general formula (3).

Wherein, Ph ₂ and Ph _'2 each represent a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). More preferably, Ph ₂ and Ph ′ ₂ represent a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a carbon number. It may be substituted with an alkylcycloalkyl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 12 carbon atoms. Ph ₂ and Ph ′ ₂ may be the same as or different from each other. These may be substituted with a substituent having the same meaning as the substituent represented by R ₃₁ to R ₃₆ in the general formula (3).

In the formula, Ph ₃ represents a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). More preferably, Ph ₃ represents a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a 6 to 12 carbon atom. It may be substituted with an alkylcycloalkyl group or an aralkyl group having 7 to 12 carbon atoms. These may be substituted with a substituent having the same meaning as the substituent represented by R ₃₁ to R ₃₆ in the general formula (3).

In the formula, Ph ₄ represents a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). More preferably, Ph ₄ represents an alkyl group or phenyl group having 1 to 20 carbon atoms, and the alkyl group or phenyl group is a substituent having the same meaning as the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). It may be substituted by a group.

In the formula, Ph ₅ , Ph ′ ₅ and Ph ″ ₅ represent a substituent. The substituent has the same meaning as the substituent represented by R ₃₁ to R ₃₆ in the general formula (3). More preferably, Ph ₅ , Ph ′ ₅ and Ph ″ ₅ represent an alkyl group or phenyl group having 1 to 20 carbon atoms, and the alkyl group or phenyl group is a substituent represented by R ₃₁ to R ₃₆ in the general formula (3). It may be substituted with a substituent having the same meaning as

Specific examples of phosphorus compounds include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-). t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 6- [ 3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3,2] dioxaphosphine Monophosphite compounds such as pin and tridecyl phosphite; 4,4′-butylidene-bis (3-methyl-6-tert-butyl) Diphosphite compounds such as ruphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phosphite); triphenylphosphonite, tetrakis (2,4- Di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) [1,1-biphenyl]- Phosphonite compounds such as 4,4'-diylbisphosphonite; phosphinite compounds such as triphenylphosphinite and 2,6-dimethylphenyldiphenylphosphinite; triphenylphosphine and tris (2,6-dimethoxyphenyl) Phosphine compounds such as phosphine; and the like.

Phosphorus compounds of the above type are, for example, “SumilizerGP” from Sumitomo Chemical Co., Ltd., “Adeka Stub PEP-24G”, “Adeka Stub PEP-36” and “Adeka Stub 3010” from ADEKA Co., Ltd., “IRGAFOS from BASF Japan K.K. “P-EPQ” is commercially available from Sakai Chemical Industry Co., Ltd. under the trade name “GSY-P101”.

The above phosphorus compounds can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within the range not impairing the object of the present invention, but 100 parts by mass of resin (acrylic resin and cellulose resin) Is usually within the range of 0.001 to 10.0 parts by mass, preferably within the range of 0.05 to 5.0 parts by mass, and more preferably within the range of 0.05 to 2.0 parts by mass. is there.

(Sulfur compounds)
The sulfur compound preferably used in the present invention is preferably a sulfur compound represented by the following general formula (6).

General formula (6)
R ₆₁ -SR ₆₂
In the formula, R ₆₁ and R ₆₂ represent a substituent. The substituent is synonymous with the substituent represented by R ₃₁ to R ₃₆ in the general formula (3).

Specific examples of the sulfur compound include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodipropioate. And pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane .

The above-mentioned types of sulfur compounds are commercially available, for example, from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TPL-R” and “Sumilizer TP-D”.

The above sulfur compounds can be used singly or in combination of two or more, and the blending amount is appropriately selected within the range not impairing the object of the present invention, but the resin (acrylic resin and cellulose resin) 100 mass. Usually within the range of 0.001 to 10.0 parts by mass, preferably within the range of 0.05 to 5.0 parts by mass, and more preferably within the range of 0.05 to 2.0 parts by mass. It is.

<Other additives>
In the optical film of the present invention, additives such as an acid scavenger, an ultraviolet absorber, a plasticizer, a mat agent, an optical anisotropy control agent and an antistatic agent may be used in combination as other additives.

(Acid scavenger)
Since decomposition is accelerated by an acid in a high temperature environment where melt casting is performed, the optical film of the present invention preferably contains an acid scavenger as a stabilizer. Any acid scavenger useful in the present invention can be used without limitation as long as it is a compound that reacts with an acid to inactivate the acid, and is described in U.S. Pat. No. 4,137,201. A compound having an epoxy group is preferred.

Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of various polyglycol diglycidyl ethers, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol. Glycol, diglycidyl ethers of glycerol, metal epoxy compounds (such as those conventionally used in and with vinyl chloride polymer compositions), epoxidized ether condensation products, diphenols of bisphenol A Glycidyl ether (ie, 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 4 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (eg Butyl epoxy stearate Epoxidized vegetable oils and other unsaturated natural oils, which may be represented and exemplified by compositions of various epoxidized long chain fatty acid triglycerides and the like (eg, epoxidized soybean oil, epoxidized linseed oil, etc.) As epoxidized natural glycerides or unsaturated fatty acids, which generally contain from 12 to 22 carbon atoms).

Further, as a commercially available epoxy group-containing epoxide resin compound, EPON 815C and other epoxidized ether oligomer condensation products of the following general formula (7) can also be preferably used.

Where n is an integer from 0 to 12. Other acid scavengers that can be used include those described in paragraphs 87 to 105 of JP-A No. 5-194788.

Each of the acid scavengers can be used alone or in combination of two or more, and the amount of the acid scavenger is appropriately selected within a range not impairing the object of the present invention. In general, it is in the range of 0.001 to 10.0 parts by mass, preferably in the range of 0.05 to 5.0 parts by mass, and more preferably in the range of 0.05 to 2.0 parts by mass.

The acid scavenger may be referred to as an acid scavenger, an acid scavenger, an acid catcher or the like with respect to the resin, but can be used in the present invention without any difference due to their names.

(UV absorber)
In the optical film of the present invention, from the viewpoint of preventing deterioration of the polarizer and the display device with respect to ultraviolet rays, the optical film is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, visible light having a wavelength of 400 nm or more is used. It is preferable to contain an ultraviolet absorber that absorbs little.

Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. However, benzophenone compounds, less colored benzotriazole compounds, and triazine compounds are preferable.

Further, ultraviolet absorbers described in JP-A Nos. 10-182621 and 8-337574, and polymer ultraviolet absorbers described in JP-A Nos. 6-148430 and 2003-113317 may be used.

Specific examples of benzotriazole ultraviolet absorbers include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzo Triazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy 3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5 '-(2-octyloxycarbonylethyl) -phenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(1-methyl-1-phenylethyl) -5 ′-(1,1,3,3-tetramethylbutyl) -phenyl) benzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H -Benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro- H- benzotriazol-2-yl) can be mentioned mixtures of phenyl] propionate, and the like.

As commercially available products, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 360 (all are manufactured by BASF Japan), LA31 (manufactured by ADEKA Corporation), RUVA-100 (Made by Otsuka Chemical).

Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-) 5-benzoylphenylmethane) and the like, but are not limited thereto.

In the present invention, the ultraviolet absorber is preferably added in the range of 0.1 to 5% by mass, and more preferably in the range of 0.2 to 3% by mass with respect to the resin (acrylic resin and cellulose resin). It is preferable to add, and it is more preferable to add within the range of 0.5 to 2% by mass. Two or more of these may be used in combination.

The benzotriazole structure or triazine structure may be part of the polymer or regularly pendant to the polymer, and part of the molecular structure of other additives such as plasticizers, antioxidants, acid scavengers, etc. May be introduced.

The conventionally known UV-absorbing polymer is not particularly limited, and examples thereof include a polymer obtained by homopolymerizing RUVA-93 (manufactured by Otsuka Chemical) and a polymer obtained by copolymerizing RUVA-93 with other monomers. . Specifically, PUVA-30M obtained by copolymerizing RUVA-93 and methyl methacrylate in a ratio (mass ratio) of 3: 7, and PUVA-50M copolymerized in a ratio of 5: 5 (mass ratio). It is done. Furthermore, the polymer etc. which are described in Unexamined-Japanese-Patent No. 2003-113317 are mentioned.

(Plasticizer)
In the optical film of the present invention, at least one plasticizer may be added to the film.

A plasticizer is generally an additive that has the effect of improving brittleness or imparting flexibility by being added to a polymer. In this case, a plasticizer is added in order to lower the melting temperature than the melting temperature alone, and to lower the melt viscosity of the film constituent material containing the plasticizer than the resin alone at the same heating temperature. Moreover, since it adds also in order to improve the hydrophilic property of a cellulose resin and to improve the water vapor transmission rate of an optical film, it has a function as a moisture permeation preventive agent.

Here, the melting temperature of the film constituent material means a temperature at which the material is heated and fluidity is developed. In order to melt and flow the resin according to the present invention, it is necessary to heat at least a temperature higher than the glass transition temperature. Above the glass transition temperature, the elastic modulus or viscosity decreases due to heat absorption, and fluidity is exhibited.

However, in the resin according to the present invention, the molecular weight of the cellulose resin may be reduced due to thermal decomposition at the same time as melting at high temperatures, which may adversely affect the mechanical properties of the resulting film. There is a need.

In order to lower the melting temperature of the film constituent material, it can be achieved by adding a plasticizer having a melting point or glass transition temperature lower than the glass transition temperature of the resin according to the present invention.

In the optical film of the present invention, it is preferable to add a plasticizer in the range of 0.1 to 20% by mass relative to the resin (acrylic resin and cellulose resin), and further in the range of 0.2 to 10% by mass. It is preferable to add at. Two or more of these may be used in combination.

In the present invention, an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid and an ester plasticizer comprising a polyhydric carboxylic acid and a monohydric alcohol are preferred.

Examples of polyhydric alcohols that are raw materials for ester plasticizers include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, xyl Mention may be made of the toll and the like. In particular, ethylene glycol, glycerin, and trimethylolpropane are preferable.

Specific examples of ethylene glycol ester plasticizers that are one of the polyhydric alcohol esters include ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, and ethylene glycol dicyclopropyl. Examples thereof include ethylene glycol cycloalkyl ester plasticizers such as carboxylate and ethylene glycol dicyclohexylcarboxylate, and ethylene glycol aryl ester plasticizers such as ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate.

These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mix of alkylate group, cycloalkylate group and arylate group, and these substituents may be covalently bonded.

Further, the ethylene glycol part may be substituted, the ethylene glycol ester partial structure may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber, etc. It may be introduced into a part of the molecular structure of the additive.

Specific examples of the glycerin ester plasticizer that is one of the polyhydric alcohol esters include glycerol alkyl esters such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol oleate propionate, and glycerol tricyclopropylcarboxylate. Glycerin cycloalkyl esters such as glycerin tricyclohexyl carboxylate, glyceryl aryl esters such as glycerin tribenzoate and glycerin 4-methylbenzoate, diglycerin tetraacetylate, diglycerin tetrapropionate, diglycerin acetate tricaprylate, diglycerin Diglycerol alkyl esters such as tetralaurate, diglycerol tetracyclobutylcarboxylate, diglycerol Diglycerol cycloalkyl esters such as La cyclopentyl carboxylate, diglycerin tetrabenzoate, diglycerin aryl ester such as diglycerin 3-methylbenzoate or the like. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond.

Furthermore, the glycerin or diglycerin part may be substituted, the partial structure of the glycerin ester or the diglycerin ester may be part of the polymer or regularly pendant, and the antioxidant, acid scavenger, You may introduce | transduce into a part of molecular structure of additives, such as a ultraviolet absorber.

Specific examples of other polyhydric alcohol ester plasticizers include polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A No. 2003-12823.

These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond.

Furthermore, the polyhydric alcohol part may be substituted, and the partial structure of the polyhydric alcohol may be a part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber. May be introduced into a part of the molecular structure of the additive.

Among the ester plasticizers composed of the polyhydric alcohol and the monovalent carboxylic acid, alkyl polyhydric alcohol aryl esters are preferable. Specifically, the ethylene glycol dibenzoate, glycerin tribenzoate, diglycerin tetrabenzoate, penta Examples include erythritol tetrabenzoate and exemplified compound 16 described in paragraph 31 of JP-A No. 2003-12823.

Specific examples of the dicarboxylic acid ester plasticizer that is one of the polyvalent carboxylic acid esters include alkyl dicarboxylic acid alkyl ester plasticizers such as didodecyl malonate, dioctyl adipate, and dibutyl sebacate. Alkyl dicarboxylic acid cycloalkyl ester plasticizers such as cyclopentyl succinate and dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, dihexyl-1,4-cyclohexane Cycloalkyl dicarboxylic acid alkyl ester plasticizers such as dicarboxylate and didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutanedicarboxylate, Cyclopropyl-1,2-cyclohexyl dicarboxylate and other cycloalkyl dicarboxylic acid cycloalkyl ester plasticizers, diphenyl-1,1-cyclopropyl dicarboxylate, di-2-naphthyl-1,4-cyclohexane dicarboxylate Cycloalkyldicarboxylic acid aryl ester plasticizers such as diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, and other aryl dicarboxylic acid alkyl ester plasticizers, dicyclopropyl phthalate, dicyclohexyl phthalate Aryl dicarboxylic acid cycloalkyl ester plasticizers such as diphenyl phthalate, di4-methylphenyl phthalate and other aryl dicarboxylic acid aryl ester plastics And the like. These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted.

The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used.

In addition, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and may be part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be introduced.

Other polycarboxylic acid ester plasticizers include alkyl polycarboxylic acid alkyl esters such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. Plasticizers, alkylpolycarboxylic acid cycloalkylester plasticizers such as tricyclohexyl tricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy- Alkyl polyvalent carboxylic acid aryl ester plasticizers such as 1,2,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2, 3,4-cyclobutanetetracarboxylate, tetra Cycloalkyl polycarboxylic acid alkyl ester plasticizers such as til-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl- Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as 1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2, Cycloalkyl polycarboxylic acid aryl ester plasticizers such as 3,4,5,6-cyclohexylhexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4 Aryl, such as 5-tetracarboxylate Carboxylic acid alkyl ester plasticizers, such as tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate, etc. Plasticizers of aryl polyvalent carboxylic acid aryl esters such as plasticizers triphenylbenzene-1,3,5-tetracarboxylate, hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate Agents.

These alkoxy groups and cycloalkoxy groups may be the same or different, and may be monosubstituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond.

Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester may be part of the polymer or may be regularly pendant to the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be.

Among the ester plasticizers composed of the polyvalent carboxylic acid and the monohydric alcohol, alkyl dicarboxylic acid alkyl esters are preferable, and specific examples include the dioctyl adipate.

Other plasticizers used in the present invention include phosphate ester plasticizers, carbohydrate ester plasticizers, polymer plasticizers, and the like.

Specific examples of the phosphoric acid ester plasticizer include phosphoric acid alkyl esters such as triacetyl phosphate and tributyl phosphate, phosphoric acid cycloalkyl esters such as tricyclopentyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, Examples thereof include phosphoric acid aryl esters such as cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixylyl phosphate, tris ortho-biphenyl phosphate. These substituents may be the same or different, and may be further substituted.

Also, it may be a mix of an alkyl group, a cycloalkyl group, and an aryl group, and substituents may be covalently bonded.

Also, alkylene bis (dialkyl phosphate) such as ethylene bis (dimethyl phosphate), butylene bis (diethyl phosphate), alkylene bis (diaryl phosphate) such as ethylene bis (diphenyl phosphate), propylene bis (dinaphthyl phosphate), phenylene bis (dibutyl) Phosphate), arylene bis (dialkyl phosphate) such as biphenylene bis (dioctyl phosphate), phosphate esters such as arylene bis (diaryl phosphate) such as phenylene bis (diphenyl phosphate) and naphthylene bis (ditoluyl phosphate). These substituents may be the same or different, and may be further substituted.

Furthermore, the partial structure of the phosphate ester may be part of the polymer or may be regularly pendant, and may be introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be. Among the above-mentioned compounds, phosphoric acid aryl ester and arylene bis (diaryl phosphate) are preferable, and specifically, triphenyl phosphate and phenylene bis (diphenyl phosphate) are preferable.

Next, the carbohydrate ester plasticizer will be described. The carbohydrate means a monosaccharide, disaccharide or trisaccharide in which the saccharide is present in the form of pyranose or furanose (6-membered ring or 5-membered ring). Non-limiting examples of carbohydrates include glucose, saccharose, lactose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose and raffinose.

The carbohydrate ester refers to an ester compound formed by dehydration condensation of a hydroxy group of a carbohydrate and a carboxylic acid, and specifically means an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester of a carbohydrate.

Examples of the aliphatic carboxylic acid include acetic acid and propionic acid, and examples of the aromatic carboxylic acid include benzoic acid, toluic acid and anisic acid.

Carbohydrates have a number of hydroxy groups depending on the type, but even if a portion of the hydroxy group reacts with a carboxylic acid to form an ester compound, the entire hydroxy group reacts with the carboxylic acid to form an ester compound. It may be formed. In the present invention, it is preferred that all of the hydroxy groups react with the carboxylic acid to form an ester compound.

Specific examples of the carbohydrate ester plasticizer include glucose pentaacetate, glucose pentapropionate, glucose pentabtylate, saccharose octaacetate, saccharose octabenzoate and the like. Among these, saccharose octaacetate, saccharose Octabenzoate is more preferred, and sucrose octabenzoate is particularly preferred.

Examples of these compounds are listed below, but the present invention is not limited thereto.

Monopet SB: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Monopet SOA: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, alicyclic hydrocarbon polymers, and ethyl polyacrylate. Acrylic polymers such as polymethyl methacrylate, copolymers of methyl methacrylate and 2-hydroxyethyl methacrylate (eg, any ratio between 1:99 and 99: 1), polyvinyl isobutyl Ethers, vinyl polymers such as poly N-vinyl pyrrolidone, styrene polymers such as polystyrene and poly 4-hydroxystyrene, polybutylene succinate, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide , Polyamide, polyureta , And a polyurea or the like.

The number average molecular weight is preferably in the range of 1,000 to 500,000, particularly preferably in the range of 5,000 to 200,000. If it is 1000 or more, the volatility can be reduced, and if it is 500000 or less, the plasticizing ability is high and the mechanical properties of the optical film are good. These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Two or more of the above polymers may be used in combination.

(Matting agent)
In the optical film according to the present invention, a matting agent can be added in order to impart slipperiness, optical and mechanical functions. Examples of the matting agent include inorganic compound fine particles and organic compound fine particles.

The shape of the matting agent is preferably a spherical shape, rod shape, needle shape, layer shape, flat plate shape or the like. Examples of the matting agent include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Examples thereof include inorganic fine particles such as oxides, phosphates, silicates, and carbonates, and crosslinked polymer fine particles.

Among these, silicon dioxide is preferable because it can reduce the haze of the film. These fine particles are preferably surface-treated with an organic substance because the haze of the film can be reduced.

The surface treatment is preferably performed with halosilanes, alkoxysilanes, silazane, siloxane, or the like. The larger the average particle size of the fine particles, the greater the sliding effect, and the smaller the average particle size, the better the transparency. The average primary particle size of the fine particles is in the range of 0.01 to 1.0 μm. The average primary particle diameter of the preferred fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 14 nm. These fine particles are preferably used for generating irregularities in the range of 0.01 to 1.0 μm on the optical film surface.

As the fine particles of silicon dioxide, Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, NAX50, etc. manufactured by Nippon Aerosil Co., Ltd. are available. P10, KE-P30, KE-P100, KE-P150 and the like can be mentioned. Aerosil 200V, R972V, NAX50, KE-P30 and KE-P100 are preferable. Two or more kinds of these fine particles may be used in combination.

¡When two or more types are used together, they can be mixed and used at an arbitrary ratio. Fine particles having different average particle sizes and materials, for example, Aerosil 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9: 0.1.

These matting agents are preferably added by kneading. Further, as another form, after a matting agent dispersed in a solvent in advance and a resin and / or plasticizer and / or an antioxidant and / or an ultraviolet absorber are mixed and dispersed, a solid material in which the solvent is volatilized or precipitated is obtained. It is preferable to use this in the process of producing the resin melt from the viewpoint that the matting agent can be uniformly dispersed in the resin.

The matting agent can be added to improve the mechanical, electrical and optical properties of the film.

The slipperiness of the resulting film is improved as these fine particles are added, but the haze increases as the fine particles are added. Therefore, the content is preferably 0.001 to 0.002 (acrylic resin and cellulose resin). It is preferably in the range of 5% by mass, more preferably in the range of 0.005 to 1% by mass, and still more preferably in the range of 0.01 to 0.5% by mass.

<Method for producing optical film>
The example of the manufacturing method of the optical film of this invention is demonstrated.

(Melt casting method)
Examples of the production method for producing the optical film of the present invention include a solution casting method, a melt casting method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretch molding method. It is done. Among these, the melt casting method is excellent for obtaining an optical film having excellent mechanical strength, surface accuracy, and the like.

Hereinafter, the method for producing the optical film of the present invention will be described by taking the melt casting method as an example.

FIG. 1 is a schematic flow sheet showing an example of the overall configuration of an apparatus for carrying out the method for producing an optical film according to the present invention, and FIG. 2 is an enlarged view of a cooling roller portion from a casting die.

In FIG. 1 and FIG. 2, the manufacturing method of the optical film by this invention is, after mixing film materials, such as a cellulose resin and an acrylic resin, using the extruder 1, it is on the 1st cooling roller 5 from the casting die 4. FIG. While melt-extruding and circumscribing the first cooling roller 5, it is further circumscribed by a total of three cooling rollers, the second cooling roller 7 and the third cooling roller 8, in order to cool and solidify to form a film 10. Next, after the film 10 peeled by the peeling roller 9 is stretched in the width direction by holding both ends of the film by the stretching device 12, the film 10 is wound by the winding device 16.

In addition, a touch roller 6 is provided to clamp the molten film on the surface of the first cooling roller 5 in order to correct the flatness. The touch roller 6 has an elastic surface and forms a nip with the first cooling roller 5. Details of the touch roller 6 will be described later.

In the method for producing an optical film according to the present invention, the conditions for melt extrusion can be carried out in the same manner as the conditions used for other thermoplastic resins such as polyester. The material is preferably dried beforehand. It is desirable to dry the moisture to 1000 ppm by mass or less, preferably 200 ppm by mass or less using a vacuum or reduced pressure dryer or a dehumidifying hot air dryer.

For example, a resin dried under hot air, vacuum, or reduced pressure is melted using an extruder 1 at an extrusion temperature within a range of 200 to 300 ° C. and filtered through a leaf disk type filter 2 to remove foreign matters.

When introducing into the extruder 1 from a supply hopper (not shown), it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere.

When additives such as plasticizer are not mixed in advance, they may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer 3.

In the present invention, the resin and other additives that are added as necessary are preferably mixed before melting, and more preferably the resin and the additive are mixed before heating. Mixing may be performed by a mixer or the like, or may be performed in the resin preparation process as described above. When a mixer is used, a general mixer such as a V-type mixer, a conical screw type mixer, a horizontal cylindrical type mixer, a Henschel mixer, or a ribbon mixer can be used.

After the film constituent materials are mixed as described above, the mixture may be directly melted using the extruder 1 to form a film, but once the film constituent materials are pelletized, the pellets are extruded. The film may be melted by the machine 1 to form a film. When the film constituent material includes a plurality of materials having different melting points, a so-called braided semi-melt is once produced at a temperature at which only a material having a low melting point is melted, and the semi-melt is supplied to the extruder 1. It is also possible to form a film by introducing it. If the film component contains a material that is easily pyrolyzed, in order to reduce the number of times of melting, a method of directly forming a film without producing pellets, or after making a paste-like semi-molten material as described above A method of forming a film is preferred.

The extruder 1 can use various commercially available extruders, but is preferably a melt-kneading extruder, and may be a single screw extruder or a twin screw extruder. When forming a film directly without producing pellets from a film constituting material, it is preferable to use a twin-screw extruder because an appropriate degree of kneading is required. However, even with a single-screw extruder, the screw shape is a Maddock type. By changing to a kneading type screw such as a unimelt type or a dull mage, moderate kneading can be obtained, so that it can be used. When a pellet or braided semi-melt is used as the film constituent material, it can be used in either a single screw extruder or a twin screw extruder.

The cooling step in the extruder 1 and after the extrusion is preferably performed by substituting with an inert gas such as nitrogen gas or reducing the pressure to reduce the oxygen concentration.

Although the preferable conditions for the melting temperature of the film constituent material in the extruder 1 vary depending on the viscosity and discharge rate of the film constituent material, the thickness of the sheet to be manufactured, etc., in general, with respect to the glass transition temperature Tg of the film Tg to Tg + 100 ° C., preferably Tg + 10 ° C. to Tg + 90 ° C. The melt viscosity at the time of extrusion is in the range of 1 to 10000 Pa · s, preferably in the range of 10 to 1000 Pa · s. Further, the residence time of the film constituting material in the extruder 1 is preferably short, and is within 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes.

The residence time depends on the type of the extruder 1 and the extrusion conditions, but can be shortened by adjusting the material supply amount, L / D, screw rotation speed, screw groove depth, and the like. is there.

The shape of the screw and the number of rotations of the extruder 1 are appropriately selected depending on the viscosity of the film constituting material, the discharge amount, and the like. In the present invention, the shear rate in the extruder 1 is in the range of 1 / second to 10,000 / second, preferably in the range of 5 / second to 1000 / second, more preferably in the range of 10 / second to 100 / second. is there.

The extruder 1 that can be used in the present invention is generally available as a plastic molding machine.

The film constituent material extruded from the extruder 1 is sent to the casting die 4 and extruded from the slit of the casting die 4 into a film shape. The casting die 4 is not particularly limited as long as it is used for producing a sheet or a film.

The material of the casting die 4 is sprayed or plated with hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. Processing such as buffing, lapping using a # 1000 or higher grinding wheel, plane cutting using a # 1000 or higher diamond grinding wheel (the cutting direction is perpendicular to the resin flow direction), electrolytic polishing, electrolytic composite polishing, etc. And the like. A preferred material for the lip portion of the casting die 4 is the same as that of the casting die 4. The surface accuracy of the lip is preferably 0.5S or less, and more preferably 0.2S or less.

The slit of the casting die 4 is configured so that the gap can be adjusted. This is shown in FIG. Of the pair of lips forming the slit 32 of the casting die 4, one is a flexible lip 33 having low rigidity and easily deformed, and the other is a fixed lip 34. A large number of heat bolts 35 are arranged at a constant pitch in the width direction of the casting die 4, that is, in the length direction of the slits 32.

Each heat bolt 35 is provided with a block 36 having an embedded electric heater 37 and a cooling medium passage, and each heat bolt 35 penetrates each block 36 vertically. The base of the heat bolt 35 is fixed to the die body 31, and the tip is in contact with the outer surface of the flexible lip 33.

While the block 36 is always air-cooled, the input to the embedded electric heater 37 is increased or decreased to increase or decrease the temperature of the block 36, thereby causing the heat bolt 35 to thermally expand and contract, thereby displacing the flexible lip 33 and thereby increasing the film thickness. adjust.

Thickness gauges are installed at the required locations in the wake of the die, and the web thickness information detected by this is fed back to the control device. This thickness information is compared with the set thickness information by the control device, and corrections coming from the device It is also possible to control the power or ON rate of the heat bolt heating element by a control amount signal. The heat bolt preferably has a length within a range of 20 to 40 cm and a diameter within a range of 7 to 14 mm, and a plurality of, for example, several tens of heat bolts are preferably arranged within a range of a pitch of 20 to 40 mm. ing. Instead of the heat bolt, a gap adjusting member mainly composed of a bolt for adjusting the slit gap by manually moving back and forth in the axial direction may be provided. The slit gap adjusted by the gap adjusting member is usually in the range of 200 to 1000 μm, preferably in the range of 300 to 800 μm, more preferably in the range of 400 to 600 μm.

The first to third cooling rollers are made of seamless steel pipe with a wall thickness in the range of 20 to 30 mm, and the surface is mirror finished. Inside, a pipe for flowing a coolant is arranged so that heat can be absorbed from the film on the roller by the coolant flowing through the pipe. Of the first to third cooling rollers, the first cooling roller 5 corresponds to the rotary support according to the present invention.

On the other hand, the touch roller 6 in contact with the first cooling roller 5 has an elastic surface and is deformed along the surface of the first cooling roller 5 by the pressing force to the first cooling roller 5. A nip is formed between the two. The touch roller 6 is also called a pinching rotary body. As the touch roller 6, a touch roller disclosed in registered patent 3194904, registered patent 3422798, Japanese Patent Application Laid-Open No. 2002-36332, Japanese Patent Application Laid-Open No. 2002-36333, or the like can be preferably used. These can also use what is marketed.

These will be described in more detail below.

FIG. 4 is a cross-sectional view showing an example of a pinching rotator. The schematic cross section of the 1st example (henceforth, touch roller A) of the touch roller 6 is shown. As shown in the drawing, the touch roller A has a flexible metal sleeve 41 with an elastic roller 42 disposed therein.

The metal sleeve 41 is made of stainless steel having a thickness of 0.3 mm and has flexibility. If the metal sleeve 41 is too thin, the strength is insufficient, whereas if it is too thick, the elasticity is insufficient. For these reasons, the thickness of the metal sleeve 41 is preferably within the range of 0.1 to 1.5 mm. The elastic roller 42 is formed in a roller shape by providing a rubber 44 on the surface of a metal inner cylinder 43 that is rotatable via a bearing. When the touch roller A is pressed toward the first cooling roller 5, the elastic roller 42 presses the metal sleeve 41 against the first cooling roller 5, and the metal sleep 41 and the elastic roller 42 have the shape of the first cooling roller 5. It deforms corresponding to the familiar shape, and forms a nip with the first cooling roller. Cooling water 45 flows in a space formed between the metal sleeve 41 and the elastic roller 42.

FIG. 5 is a cross-sectional view in a plane perpendicular to the rotation axis showing a second example of a pinching rotating body (a second example of the touch roller 6 (hereinafter referred to as touch roller B)).

FIG. 6 is a cross-sectional view of a plane including a rotation axis showing an example of a second example (touch roller B) of the sandwiching rotary body.

5 and 6 show a touch roller B which is another embodiment of the pinching rotary member. The touch roller B includes a flexible, seamless stainless steel pipe (thickness 4 mm) outer cylinder 51, and a high-rigidity metal inner cylinder 52 disposed on the same axis as the inner cylinder 51. It is roughly composed. A coolant 54 flows in the space 53 between the outer cylinder 51 and the inner cylinder 52. Specifically, in the touch roller B, outer

cylinder support flanges

56a and 56b are attached to the

rotating shafts

55a and 55b at both ends, and a thin metal outer cylinder 51 is attached between the outer peripheral portions of the both outer

cylinder support flanges

56a and 56b. Yes.

A fluid supply pipe 59 is disposed in the same axial center in a fluid discharge hole 58 formed in the axial center portion of one rotary shaft 55a and forming a fluid return passage 57. The fluid supply pipe 59 is thin-walled. It is connected and fixed to a fluid shaft cylinder 60 arranged at the axial center in the metal outer cylinder 51. Inner

cylinder support flanges

61a and 61b are attached to both ends of the fluid shaft cylinder 60, respectively, and are within a range of about 15 to 20 mm from between the outer peripheral parts of the inner

cylinder support flanges

61a and 61b to the outer cylinder support flange 56b on the other end side. A metal inner cylinder 52 having a certain thickness is attached.

A cooling liquid flow space 53 of, for example, about 10 mm is formed between the metal inner cylinder 52 and the thin metal outer cylinder 51, and the metal inner cylinder 52 has a flow space 53 and an inner space near both ends. An outlet 52a and an inlet 52b are formed to communicate with the

intermediate passages

62a and 62b outside the

cylinder support flanges

61a and 61b, respectively.

In addition, the outer cylinder 51 is thinned within a range in which the thin cylinder theory of elastic mechanics can be applied in order to have flexibility, flexibility and resilience close to rubber elasticity. The flexibility evaluated by the thin-walled cylinder theory is expressed by the thickness t / roller radius r, and the flexibility increases as t / r decreases.

In this touch roller B, the flexibility is the optimum condition when t / r ≦ 0.03. Usually, a commonly used touch roller has a roller diameter R = 200 to 500 mm (roller radius r = R / 2), a roller effective width L = 500 to 1600 mm, and r / L < 1 is a horizontally long shape.

Here, t / r ≦ 0.03, but in the case of a general roller diameter R = 200 to 500 mm, flexibility is sufficiently obtained particularly when 2 mm ≦ t ≦ 5 mm. In addition, thinning by machining can be easily performed, which is in a very practical range. If the wall thickness is 2 mm or more, highly accurate processing can be performed by elastic deformation during processing.

The converted value of 2 mm ≦ t ≦ 5 mm is 0.008 ≦ t / r ≦ 0.05 with respect to a general roller diameter, but in practical use, the roller diameter under the condition of t / r≈0.03. It is preferable to increase the wall thickness in proportion to. For example, when the roller diameter is R = 200, t = 2 to 3 mm, and when the roller diameter is R = 500, t = 4 to 5 mm is preferable.

The touch rollers A and B are urged toward the first cooling roller by urging means (not shown). The urging force of the urging means is F, and the value F / W (linear pressure) obtained by dividing the width of the film in the nip along the rotation axis of the first cooling roller 5 is 9.8 to 147 N / cm. It is preferable to set within the range.

According to this embodiment, a nip is formed between the touch rollers A and B and the first cooling roller 5, and the flatness of the film is corrected while the film passes through the nip. Therefore, since the touch roller is composed of a rigid body and the nip is not formed between the touch roller and the first cooling roller, the film is sandwiched for a long time with a small linear pressure, so that the flatness can be more reliably corrected. Can do.

That is, if the linear pressure is 9.8 N / cm or more, the die line can be sufficiently eliminated. Conversely, if the linear pressure is 147 N / cm or less, the film easily passes through the nip, and the film thickness becomes uniform.

Moreover, since the surfaces of the touch rollers A and B can be made smoother than when the surfaces of the touch rollers are made of rubber by forming the surfaces of the touch rollers A and B with a metal, a highly smooth film can be obtained. Obtainable. In addition, as a material of the elastic body 44 of the elastic roller 42, ethylene propylene rubber, neoprene rubber, silicon rubber, or the like can be used.

Now, in order to eliminate the die line satisfactorily by the touch roller 6, it is preferable that the viscosity of the film when the touch roller 6 sandwiches the film is in an appropriate range. Cellulose resins are known to have a relatively large change in viscosity with temperature.

Therefore, in order to set the viscosity when the touch roller 6 clamps the optical film to an appropriate range, it is preferable to set the temperature of the film when the touch roller 6 clamps the film to an appropriate range. When the glass transition temperature of the optical film is Tg, it is preferable to set the temperature T of the film immediately before the film is sandwiched between the touch rollers 6 so as to satisfy Tg <T <Tg + 110 ° C.

Preferably, Tg + 10 ° C. <T2 <Tg + 90 ° C., and more preferably Tg + 20 ° C. <T2 <Tg + 70 ° C. In order to set the temperature of the film when the touch roller 6 clamps the optical film to an appropriate range, the first cooling roller 5 from the position where the melt extruded from the casting die 4 contacts the first cooling roller 5. What is necessary is just to adjust the length along the rotation direction of the 1st cooling roller 5 to the nip with the touch roller 6.

Preferred materials for the first roller 5 and the second roller 6 include carbon steel, stainless steel, resin, and the like. The surface accuracy is preferably high, and the surface roughness is preferably 0.3 S or less, more preferably 0.01 S or less. Further, by reducing the pressure from the opening (lip) of the casting die 4 to the first roller 5 to 70 kPa or less, the above-described die line correction effect is more greatly manifested. Preferably, the reduced pressure is in the range of 50 to 70 kPa.

Although there is no restriction | limiting in particular as a method of keeping the pressure of the part from the opening part (lip | rip) of the casting die 4 to the 1st roller 5 below 70 kPa, Cover the roller periphery from the casting die 4 with a pressure-resistant member, and reduce pressure There are methods. At this time, the suction device is preferably subjected to a treatment such as heating with a heater so that the device itself does not become a place where the sublimate is attached. In the present invention, if the suction pressure is too small, the sublimate cannot be sucked effectively.

In the present invention, a molten film-like resin from the T-die 4 is cooled and solidified while being conveyed in close contact with the first roller (first cooling roller) 5, the second cooling roller 7, and the third cooling roller 8. The unstretched film 10 is obtained.

In the embodiment of the present invention shown in FIG. 1, the cooled and solidified unstretched film 10 peeled from the third cooling roller 8 by the peeling roller 9 is guided to a stretching machine 12 via a dancer roller (film tension adjusting roller) 11. Therefore, the film 10 is stretched in the transverse direction (width direction) as necessary. By this stretching, the molecules in the film are oriented.

Then, it is transported by the

transport rollers

13, 14 and 15, and wound up by the winding roller F of the winding device 16. As a method for stretching the film in the width direction, a known tenter or the like can be preferably used.

The glass transition temperature Tg of the film constituting material can be controlled by varying the material type constituting the film and the ratio of the constituting material. When a retardation film is produced as an optical film, Tg is preferably 120 ° C. or higher, preferably 135 ° C. or higher. In the liquid crystal display device, in the image display state, the temperature environment of the film changes due to the temperature rise of the device itself, for example, the temperature rise derived from the light source.

At this time, if the Tg of the film is higher than the film's operating temperature, the retardation value derived from the orientation state of the molecules fixed inside the film by stretching and the dimensional shape as the film do not significantly change, and stable performance. Indicates.

Tg is preferably 250 ° C. or lower. If the Tg of the film is 250 ° C. or lower, the temperature can be kept low when the film constituent material is made into a film, the energy consumption for heating can be reduced, and the material itself can be decomposed or made into a film. The coloring by does not occur.

In the stretching step, known heat setting conditions, cooling, and relaxation treatment may be performed, and it may be appropriately adjusted so as to have characteristics required for the target optical film.

<Polarizing plate>
When using the optical film of this invention as a protective film for polarizing plates, a polarizing plate can be produced by a general method. It is preferable that an adhesive layer is provided on the back side of the optical film of the present invention, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution.

¡An opposite film is pasted on the other side. As the counter film, the optical film of the present invention may be used, or another polarizing plate protective film may be used. For example, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4FR-4, KC4FR-3, KC4FR-3, KC4FR-4 -1, KC8UY-HA, KC8UX-RHA, KC6UA-W or higher, manufactured by Konica Minolta Advanced Layer Co., Ltd.) and the like are preferably used.

The thickness of the opposing film is preferably in the range of 20 to 60 μm. If it is 20 micrometers or more, the intensity | strength of a film is high and it is easy to bond with a polarizer. Moreover, if it is 60 micrometers or less, a polarizing plate will be hard to warp and a low-cost polarizing plate can be produced.

A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.

The polarizer is formed by forming a polyvinyl alcohol aqueous solution into a film and dyeing the film by uniaxial stretching or dyeing or uniaxially stretching, and then performing a durability treatment with a boron compound.

As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 ⁴ to 1.0 × 10 ⁹ Pa in at least a part of the pressure-sensitive adhesive layer is used. Preferably, a curable pressure-sensitive adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the pressure-sensitive adhesive is applied and bonded is suitably used.

Specific examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types, Examples include anaerobic pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.

The above-mentioned pressure-sensitive adhesive may be a one-component type or a type in which two or more components are mixed before use.

The pressure-sensitive adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type. The concentration of the pressure-sensitive adhesive solution may be appropriately determined depending on the film thickness after adhesion, the coating method, the coating conditions, and the like, and is usually in the range of 0.1 to 50% by mass.

<Liquid crystal display device>
By incorporating the polarizing plate bonded with the optical film of the present invention into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility, but particularly outdoors such as large liquid crystal display devices and digital signage. It is preferably used for a liquid crystal display device for use. The polarizing plate according to the present invention is preferably bonded to a liquid crystal cell via the adhesive layer or the like.

The polarizing plate according to the present invention is a reflective type, transmissive type, transflective LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type (including FFS type), etc. Although it is used in LCDs of various driving methods, it is preferably used in an IPS type in which a hue change due to a viewing angle is small. In particular, in a large-screen display device having a screen of 30 or more, especially 30 to 54, there is no white spot at the periphery of the screen and the effect is maintained for a long time.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

[Example 1]
Tables 1 and 2 show the monomer composition ratio of the acrylic resin. The acrylic resins shown in Table 1 and Table 2 were synthesized by known methods. In Tables 1 and 2, MMA represents methyl methacrylate, ACMO represents acryloylmorpholine, and VP represents N-vinylpyrrolidone.

The following acrylic resins A to C3 were synthesized by a known method.

A: Monomer (MMA 100%), Mw 100,000 B1: Monomer mass ratio (MMA: ACMO = 90: 10), Mw 100,000 B2: Monomer mass ratio (MMA: ACMO = 80: 20), Mw 100,000 B3: Monomer mass ratio ( MMA: ACMO = 60: 40), Mw 100,000 C1: monomer mass ratio (MMA: VP = 90: 10), Mw 100,000 C2: monomer mass ratio (MMA: VP = 80: 20), Mw 100,000 C3: monomer mass ratio (MMA: VP = 60: 40), Mw 100,000 <Preparation of optical film 101>
As described below, the acrylic resin A and various additives were mixed, and an optical film 101 was produced by a melt casting method.

Acrylic Resin A 100 parts by mass Sumilizer GS (Specific Example of Compound of Carbon Radical Scavenger I-10
; Manufactured by Sumitomo Chemical Co., Ltd.) 0.25 parts by mass IRGANOX 1010 (antioxidant; manufactured by BASF Japan Ltd.)
0.5 parts by mass GSY-P101 (antioxidant; manufactured by Sakai Chemical Industry Co., Ltd.) 0.25 parts by mass Acetylacetonate copper (II) (organic copper compound) 0.0208 parts by mass (copper (acetylacetonate) The copper ion content of II) is 24.28% by mass, and the copper ion content in 0.0208 parts by mass of copper (II) acetylacetonate is 0.00505 parts by mass. (The copper ion content is 50 ppm by mass.)
The above mixture was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized.

Using this pellet, it was melted at 250 ° C. in a nitrogen atmosphere, extruded from the casting die 4 onto the first cooling roller 5, and formed by pressing the film between the first cooling roller 5 and the touch roller 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. Touch roller A was used as a touch roller, and 80 ° C. water was allowed to flow as cooling water therein.

The first cooling from the position where the resin extruded from the casting die 4 contacts the first cooling roller 5 to the position at the upstream end in the rotation direction of the first cooling roller 5 in the nip between the first cooling roller 5 and the touch roller 6. The length along the peripheral surface of the roller 5 was set to 20 mm. Thereafter, the touch roller 6 was separated from the first cooling roller 5, and the temperature T of the melted part immediately before being pressed between the first cooling roller 5 and the nip between the touch roller 6 was measured.

In the present embodiment, the temperature T of the melted portion immediately before being squeezed by the nip between the first cooling roller 5 and the touch roller 6 is a position 1 mm upstream from the nip upstream end P2, and a thermometer (an independent meter). This was measured by HA-200E). As a result of the measurement in this example, the temperature T was 141 ° C.

The linear pressure of the touch roller 6 against the first cooling roller 5 was 14.7 N / cm. Furthermore, after being introduced into a tenter and stretched 1.3 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 having 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%, to produce an optical film 101.

In addition, the extrusion amount and the take-up speed were adjusted so that the optical film 101 had a thickness of 30 μm, and the finished film width was slit and wound so that the width 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.

<Preparation of optical films 102 to 136>
Optical films 102 to 136 were similarly prepared except that the acrylic resin, cellulose resin, organic copper compound, and film thickness were changed as shown in Tables 1 and 2 in the production of the optical film 101.

In addition, the copper addition amount of Table 1 and Table 2 represents the content rate of the copper ion with respect to the mass of an optical film in mass ppm, and the copper addition amount of Table 1 and Table 2, and the organic copper shown below The addition amount of the organic copper compound was determined from the copper content in the compound. The addition amount of the cellulose resin of Table 1 and Table 2 represents the content rate (mass%) of a cellulose resin when the total resin is 100 mass%.

The contents of the cellulose resins listed in Tables 1 and 2 are described below.

CAP482-20 (degree of acetylation: 1.3% by mass, degree of propionylation: 48% by mass, hydroxy group content: 1.7% by mass, manufactured by Eastman Chemical)
CAB171-15 (degree of butyrylation: 17% by mass, hydroxy group content: 1.5% by mass, manufactured by Eastman Chemical)
CAB381-20 (degree of butyrylation: 37% by mass, degree of acetylation: 13.5% by mass, hydroxy group content: 1.8% by mass, manufactured by Eastman Chemical)
Etocel 70 (ethyl cellulose, manufactured by Nisshinsei Co., Ltd.)
The copper compound types of the organic copper compounds shown in Tables 1 and 2 and the copper ion content in the organic copper compound are described below.

ACAC: acetylacetonate copper (II) (molecular weight: 261.79, copper ion content: 24.28% by mass)
GLUC: copper (II) gluconate (molecular weight: 453.55, copper ion content: 14.01% by mass)
GLYC: Glycinato copper (II) (molecular weight: 207.67, copper ion content: 30.60% by mass)
BIBA: Copper (II) bisisobutyrate (molecular weight: 237.74, copper ion content: 26.73% by mass)
TFAC: trifluoroacetylacetonate copper (II) (molecular weight: 369.7, copper ion content: 17.19% by mass)
PB15: Pigment Blue 15 (molecular weight: 576.08, copper ion content: 11.03 mass%)
<Evaluation of optical film>
(Tear strength)
As an evaluation of the strength of the optical film, the tear strength was measured by the following method. The tear strength of the Elmendorf method was measured with a light load tear device manufactured by Toyo Seiki Co., Ltd. according to JIS K 7128-1991. The measurement results are shown in Tables 1 and 2 in units of mN.

(Coloring)
A 30 mm square sample of the optical film was cut out and its absorption spectrum was measured using a spectrophotometer U-3310 manufactured by Hitachi High-Technologies Corporation to calculate tristimulus values X, Y, and Z. From these tristimulus values X, Y, and Z, a yellow index YI was calculated based on JIS-K7103. Moreover, visual observation was performed and the following evaluation criteria evaluated. The results are shown in Tables 1 and 2.

○: YI is 0.8 or less and no coloration is visually observed Δ: YI is in the range of 0.8 to 1.0 and no coloration is visually observed ×: YI is 1 or more, or visual coloration (retardation value)
The in-plane retardation value Ro and the retardation value Rt in the thickness direction were measured at a light wavelength of 590 nm in a 23 ° C./55% RH environment by the method described in the section (Measurement Method of Retardation Value). The results are shown in Tables 1 and 2.

From Tables 1 and 2, it can be seen that the addition of 20 to 100 ppm by mass of copper ions improves the tear strength and reduces the coloration. Furthermore, it turns out that tear strength improves by adding a cellulose resin. Moreover, it turns out that tear strength improves and the retardation value of thickness direction approaches 0 because acrylic resin has an amide group. Moreover, it turned out that the optical film 112 is visually colored blue among the optical films whose coloring was “x”.

[Example 2]
<Preparation of polarizing plate>
Polarizing plates 101 to 136 using the optical films 101 to 136 produced in Example 1 were produced 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, the optical films 101 to 136 were each subjected to corona discharge treatment and bonded to one side of the polarizer using an acrylic adhesive.

Further, on the other surface of the polarizer, as a counter film, Konica Minolta Advanced Layer Co., Ltd. manufactured by Konica Minolta Advanced Layer KC6UA-W (thickness 60 μm) was laminated using a polyvinyl alcohol-based adhesive. It dried and produced the polarizing plates 101-136.

<Production of liquid crystal display device>
A liquid crystal display device was produced using each of the produced polarizing plates 101 to 136.

A liquid crystal cell having glass on both sides was prepared by peeling off the polarizing plate attached to both sides of the liquid crystal panel of 42 type liquid crystal television (VIERA TH-L42G3) manufactured by Panasonic Corporation.

The polarizing plates 101 to 136 thus prepared are arranged in such a manner that the optical film is on the glass surface side of the liquid crystal cell and the absorption axis is oriented in the same direction as the polarizing plate previously bonded. The liquid crystal display devices 101 to 136 were produced by bonding to both surfaces.

The viewing angle characteristics and the hue of white display were evaluated using the liquid crystal display devices 101 to 136 manufactured as described above. The results are shown in Table 3.

<Evaluation of liquid crystal display device>
(Viewing angle characteristics)
After the liquid crystal display device was stored at 60 ° C. and 90% RH for 1000 hours, the viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. The sum of the absolute values of the angles at which the contrast ratio (white transmittance / black transmittance) is 10 in the vertical and horizontal directions was determined with the direction of the normal of the display surface being 0 degree. The following criteria evaluated. The viewing angle characteristic is preferably ◯ level or higher, and more preferably ◎, but if it is Δ level or higher, there is no practical problem.

A: 320 degrees or more B: 310 degrees or more and less than 320 degrees B: 300 degrees or more and less than 310 degrees X: Less than 300 degrees.

(Hue of white display)
The screen of the liquid crystal display device was allowed to emit white light, the emission spectrum of the screen was measured using a spectrocolorimeter CM-2500d (manufactured by Konica Minolta Optics), and tristimulus values X, Y, and Z were calculated. From these tristimulus values X, Y, and Z, a yellow index YI was calculated based on JIS-K7103. Moreover, visual observation was also performed and the following evaluation criteria evaluated.

○: YI is 0.8 or less and no coloration is visually observed Δ: YI is in the range of 0.8 to 1.0 and no coloration is visually observed ×: YI is Table 3 shows the results of one or more or visually recognized coloring.

Table 3 shows that the hue of the screen when the liquid crystal display device displays white is improved by adding copper ions. It can also be seen that the viewing angle characteristics are improved when the acrylic resin has an amide group, and the viewing angle characteristics are improved when the cellulose resin is added. Further, it was found that the liquid crystal display device 112 of the liquid crystal display devices having a white display hue of “×” was visually colored blue.

Since the optical film of the present invention has high strength, high transparency, and no coloration, it can be applied to reproduce a high-quality image on a large liquid crystal display device. Can be manufactured. In addition, since the optical film of the present invention has a small phase difference, the color does not change depending on the viewing direction when it is applied to an IPS liquid crystal display device, and can be applied to a high-quality image display device.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roller)
6 Nipping pressure rotating body (touch roller)
7 Rotating support (second cooling roller)
8 Rotating support (3rd cooling roller)
DESCRIPTION OF SYMBOLS 9 Peeling roller 11

Dancer roller

13, 14, 15 Conveyance roller 10 Film 12 Stretching machine 16 Winding device 31 Die body 32 Slit 41 Metal sleeve 42 Elastic roller 43 Metal inner cylinder 44 Rubber 45 Cooling water 51 Outer cylinder 52 Inner cylinder 53 Space 54

Coolant

55a,

55b Rotating shaft

56a, 56b Outer cylinder support flange 60

Fluid shaft cylinder

61a, 61b Inner

cylinder support flange

62a, 62b Intermediate passage

Claims

An optical film comprising an acrylic resin and copper ions, wherein the content of the copper ions is in the range of 20 to 100 ppm by mass with respect to the optical film.
The optical film according to claim 1, wherein the acrylic resin has an amide group.
The optical film according to claim 1, comprising a cellulose resin.
The optical film according to any one of claims 1 to 3, wherein the film thickness is in the range of 10 to 45 µm.
It is a manufacturing method of the optical film which manufactures the optical film as described in any one of Claim 1- Claim 4, Comprising: The said copper ion is added as copper gluconate or acetylacetonate copper, It is characterized by the above-mentioned. A method for producing an optical film.
An optical film manufacturing method for manufacturing the optical film according to any one of claims 1 to 4, wherein the optical film is formed by a melt casting method.
A polarizing plate comprising the optical film according to any one of claims 1 to 4.
The optical film according to any one of claims 1 to 4, a polarizer, and a counter film are provided in this order, the counter film contains a cellulose resin, and the thickness of the counter film is 20 to 60 μm. A polarizing plate characterized by being in the range of.
A liquid crystal display device comprising the polarizing plate according to claim 7 or 8.