JP5942710B2 - Optical film, polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to an optical film, a polarizing plate, and a liquid crystal display device. More specifically, an optical film having excellent retardation value development and small variation in retardation value in the thickness direction of the film due to humidity variation, and a polarizing plate and a liquid crystal display device having the durability such as moisture and heat resistance provided therewith About.

  As an optical film used for a liquid crystal display device, a cellulose ester film has been mainly used. However, since the cellulose ester film is highly moisture permeable, it can easily cause fluctuations in the retardation value (retardation value) of the optical film by allowing moisture to penetrate inside. As a result, the color of the liquid crystal display device is increased. There was a problem of unevenness.

  As a method for improving the fluctuation of the retardation value of the cellulose ester film, it is possible to reduce the film thickness or to add a large amount of additives to control moisture permeability. When a large amount of additive is added, the retardation value decreases, and therefore a compound having a high retardation value increasing ability is required.

  For example, a 1,3,5-triazine compound has been proposed as a compound having a high retardation value increasing ability (see, for example, Patent Document 1). However, even when the compound was used, the retardation expression was insufficient. Further increasing the amount of the compound added to increase retardation development, a polarizing plate produced using a thinned optical film containing the compound, and a liquid crystal display device using the polarizing plate are resistant to moisture and heat. Inferior in durability, etc. When placed under high temperature and high humidity, problems such as bleeding out and uneven color of the display device were also observed.

  In addition, when a large amount of an additive is added to control moisture permeability, depending on the type of the additive, the compatibility with the cellulose ester is deteriorated, and the addition amount is limited.

JP 2006-188718A

  The present invention has been made in view of the above-mentioned problems and circumstances, and the solution is an optical that has a high retardation value and has a small variation in the retardation value in the thickness direction of the film due to a variation in humidity. Is to provide a film. Another object of the present invention is to provide a polarizing plate and a liquid crystal display device that are excellent in heat and moisture resistance such as color unevenness of the display device provided with the optical film.

  The present inventor is an optical film containing a cellulose ester and a compound having a function of increasing the retardation value in the process of examining the cause of the above-mentioned problem, and has a specific retardation value and humidity fluctuation It has been found that the above-mentioned problems can be solved by an optical film in which the fluctuation of the retardation value due to is within a specific range.

  Among them, an optical film containing a benzoxazinone compound having a specific structure together with a cellulose ester has high retardation expression, small fluctuation of the retardation value due to humidity fluctuation, and resistance to moisture and heat such as color unevenness of the display device. It was found that an excellent optical film can be provided. Moreover, it discovered that the said compound was excellent also in bleed-out tolerance.

  Furthermore, in order to control the moisture permeability of the optical film, a compound having a molecular weight other than the above-mentioned benzoxazinone compound having a specific structure of 10,000 or less is contained in a specific range, and a specific acyl group It has been found that by using a cellulose ester having a substituent and a substitution degree, the heat and humidity resistance is further improved, and the present invention has been achieved.

  That is, the said subject which concerns on this invention is solved by the following means.

1. An optical film containing a compound having a function of raising the at least cellulose ester and retardation value, the optical film, meets all the conditions from the following conditions 1 to condition 3, and the retardation value An optical film , wherein the compound having a function of increasing is a compound represented by the following general formula (1) .

  Condition 1: An in-plane retardation value Ro (590) represented by the following formula (i) measured at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55% is in the range of 30 to 150 nm.

Formula (i): Ro (590) = (n x -n y) × d
Condition 2: Retardation value Rt (590) in the thickness direction represented by the following formula (ii) measured at a wavelength of 590 nm under an environment of a temperature of 23 ° C. and a relative humidity of 55% is within a range of 70 to 300 nm. is there.

Formula (ii): Rt (590) = {(n _x + n _y ) / 2−n _z } × d
Condition 3: The amount of change in retardation value Rt (590) in the thickness direction (ΔRt (590)) when the relative humidity is changed to a range of 20 to 80% in an environment of a temperature of 23 ° C. is 0 to It is in the range of 10 nm.
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x which refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]

（一般式（１）において、Ｒ_１３及びＲ_２３は各々置換基を表す。ｋ３は１〜５の整数を表す。ｍ３は０〜４の整数を表す。）
２．前記一般式（１）で表される化合物以外に、分子量が１００００以下である化合物を、セルロースエステル１００質量部に対して６〜４０質量部の範囲内で含有することを特徴とする第１項に記載の光学フィルム。

(In General Formula (1), R ₁₃ and R ₂₃ each represent a substituent. K3 represents an integer of 1 to 5. m3 represents an integer of 0 to 4.)
2 . The 1st term | claim characterized by containing the compound whose molecular weight is 10,000 or less in the range of 6-40 mass parts with respect to 100 mass parts of cellulose esters other than the compound represented by the said General formula (1). the optical film according to.

3 . 3. The optical film according to item 2, wherein the compound having a molecular weight of 10,000 or less is at least one selected from a sugar ester compound, a polyester compound, and an acrylic compound.

4 . The optical film according to any one of Items 1 to 3 , wherein the cellulose ester satisfies both of the following formulas (a) and (b).

Formula (a) 2.0 ≦ X + Y ≦ 2.6
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group. Y represents the degree of substitution of the propionyl group or butyryl group or the total degree of substitution thereof.)
5 . A polarizing plate, wherein the optical film according to any one of items 1 to 4 is bonded to a polarizer with an active energy ray-curable adhesive.

6 . 6. A liquid crystal display device, wherein the polarizing plate according to item 5 is provided in at least one of the liquid crystal cells.

  By the above means of the present invention, it is possible to provide an optical film having a high retardation value and having a small variation in retardation value in the thickness direction of the film due to humidity variation. Another object of the present invention is to provide a polarizing plate and a liquid crystal display device (hereinafter also simply referred to as a display device) having excellent durability such as heat and moisture resistance such as color unevenness of the display device provided with the optical film.

  The expression mechanism and action mechanism of the effects of the present invention are not clear, but are presumed as follows.

  According to the study by the present inventors, the color unevenness when the display device is placed under high humidity is more in-plane and in the thickness direction than the fluctuation of the retardation value Ro in the film plane due to the humidity fluctuation. It was found that this can be improved by suppressing the fluctuation of the retardation value Rt in the thickness direction of the film, which is determined by the refractive index of the film. Therefore, it is important to control the amount of change in retardation value Rt in the thickness direction of the film due to humidity fluctuations (ΔRt (590) in the present application) to a specific value or less.

  Further, according to the study by the present inventors, the change in the retardation value Rt in the thickness direction of the film due to the humidity change is a cellulose that expresses a phase difference rather than the action of water molecules on the hydroxy groups of the cellulose ester. It was presumed to be generated by the coordination of water molecules to the carbonyl group of the ester.

The compound represented by the general formula (1) according to the present invention introduces a cellulose ester by introducing a substituent with —OCO— as a linking group into a phenyl group substituted at a specific position with respect to the benzoxazinone skeleton. It has been found that a high retardation value is imparted to the optical film by improving the compatibility with the optical film. Furthermore, it discovered that the optical film which added the benzoxazinone compound which has the said specific structure suppressed the coordination of the water molecule to a cellulose ester by the said orientation, and has high heat-and-moisture resistance. When the optical film of the present invention containing the compound is used for a polarizing plate, color unevenness due to water content of the liquid crystal display device can be remarkably suppressed due to improvement in heat and moisture resistance.
Furthermore, by including a compound having a specific molecular weight other than the compound represented by the general formula (1), it is possible to reduce the influence of humidity by giving the optical film a function of making it difficult to absorb moisture. It is presumed that by adopting a cellulose ester having a low carbonyl group and a low substitution degree of acyl group, it is possible to reduce the coordination of water molecules to the carbonyl group and improve the wet heat resistance comprehensively.

Schematic diagram of an example of the dope preparation step, casting step and drying step of the solution casting film forming method Schematic sectional view showing an example of the configuration of a polarizing plate provided with the optical film of the present invention and a liquid crystal display device provided with the polarizing plate

The optical film of the present invention is an optical film containing a compound having a function of raising the at least cellulose ester and retardation value, the optical film, to meet all the conditions from the condition 1 to condition 3, And the compound which has a function which raises the said retardation value is a compound represented by the said General formula (1) , ie, has a specific retardation value, and the fluctuation | variation of the retardation value by humidity fluctuation | variation is It is characterized by being within a specific range, and this feature is a technical feature common to the inventions according to claims 1 to 6 .

The embodiments of the present invention, 6 from the viewpoint of the effect expression of the present invention, the molecular weight other than the compound represented by previous following general formula (1) is 10,000 or less compounds, based on 100 parts by weight of cellulose ester It is preferable to contain in the range of 40 parts by mass, and the compound having a molecular weight of 10,000 or less is at least one selected from a sugar ester compound, a polyester compound and an acrylic compound. This is preferable because the effect of reducing the retardation value due to humidity fluctuation can be obtained.

  Furthermore, in this invention, it is preferable that the said cellulose ester is a cellulose ester which has all the said formula (a) and (b), and has the substitution degree of a specific substituent and a specific acyl group.

  Furthermore, it is preferable that the optical film is bonded to a polarizer with an active energy ray-curable adhesive to form a polarizing plate, and the polarizing plate is suitably included in a liquid crystal display device.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Optical film of the present invention>
The optical film of the present invention includes at least a cellulose ester, a compound having a function of increasing a retardation value, and other optional components, and satisfies all the conditions from Condition 1 to Condition 3 below. .

  Condition 1: An in-plane retardation value Ro (590) represented by the following formula (i) measured at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55% is in the range of 30 to 150 nm.

Formula (i): Ro (590) = (n x -n y) × d
Condition 2: Retardation value Rt (590) in the thickness direction represented by the following formula (ii) measured at a wavelength of 590 nm under an environment of a temperature of 23 ° C. and a relative humidity of 55% is within a range of 70 to 300 nm. is there.

Formula (ii): Rt (590) = {(n _x + n _y ) / 2−n _z } × d
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
These retardation values can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

  When the retardation value of the optical film is in the range of the retardation values Ro (590) and Rt (590), it is suitable for increasing the viewing angle of the vertical alignment type liquid crystal display device.

  Condition 3: The amount of change in retardation value Rt (590) in the thickness direction (ΔRt (590)) when the relative humidity is changed to a range of 20 to 80% in an environment of a temperature of 23 ° C. is 0 to It is in the range of 10 nm.

Specifically, after conditioning the optical film at 23 ° C. and 20% RH for 5 hours, the Rt value measured in the same environment was measured, and this was set to Rt _20% (590). After adjusting the humidity at 80% RH for 5 hours, the Rt value measured in the same environment is obtained and this is set to Rt _80% (590), and the change amount ΔRt (590) is obtained from the following equation.

ΔRt (590) = | Rt _20% (590) −Rt _80% (590) |
A smaller value indicates that the value is more stable against humidity fluctuations.

  An optical film having a high retardation value and having a small variation in the retardation value in the thickness direction of the film due to humidity variation is provided by the optical film satisfying all the conditions from condition 1 to condition 3. In addition, a polarizing plate and a liquid crystal display device, which are provided with the optical film and are excellent in heat and moisture resistance, can be provided.

<Compound having a function of increasing retardation value>
The compound having the function of increasing the retardation value in the present application means that the retardation value Rt (590) in the thickness direction of the optical film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cellulose ester is not added. The compound which has a function which shows a 1.1 times or more value compared with the optical film. Hereinafter, in this application, it may be simply referred to as a retardation increasing agent or a retardation developer.

<Compound represented by the general formula (1)>
Compounds having a function of raising the retardation value according to the present invention, Ru compound der represented by the following general formula (1).

（一般式（１）において、Ｒ_１３及びＲ_２３は各々置換基を表す。ｋ３は１〜５の整数を表す。ｍ３は０〜４の整数を表す。）
ベンゾオキサジノン骨格に対して、特定の位置に置換するフェニル基に−ＯＣＯ−を連結基として置換基を導入することで、セルロースエステルとの相互作用が向上し、相溶性、及び配向性が向上して、リターデーション発現性の高い光学フィルムを得ることができる。一般式（１）で表される化合物は、セルロースエステルと水素結合を形成することから、水分子の配位を抑制して優れた耐湿熱性を発現することによって、当該光学フィルムは、液晶表示装置の湿度変動による色ムラを効果的に改善できる。

(In General Formula (1), R ₁₃ and R ₂₃ each represent a substituent. K3 represents an integer of 1 to 5. m3 represents an integer of 0 to 4.)
By introducing a substituent with -OCO- as the linking group to the phenyl group substituted at a specific position with respect to the benzoxazinone skeleton, the interaction with the cellulose ester is improved, and the compatibility and orientation are improved. And an optical film with high retardation expression can be obtained. Since the compound represented by the general formula (1) forms a hydrogen bond with the cellulose ester, the optical film has a liquid crystal display device by exhibiting excellent moisture and heat resistance by suppressing coordination of water molecules. Color unevenness due to humidity fluctuations can be effectively improved.

In the general formula (1), R ₁₃ represents a substituent. Examples of the substituent represented by R ₁₃ include an alkyl group (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, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), alkyloxy group (for example, alkoxy group, t-butoxy group, etc.) ), An aryloxy group (eg, phenoxy group, naphthoxy group, etc.), an alkylamino group (eg, ethylamino group, etc.), an arylamino group (eg, phenylamino group, etc.), an alkylthio group (eg, methylthio group, 2- Ethylhexylthio group, etc.), arylthio group (eg, phenylthio group, etc.), hetero A ring group (for example, pyridyl group, pyrimidyl group, oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group, etc.), alkenyl group (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl- 3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc.), alkynyl group (eg, propargyl group, etc.), alkylsulfonyl group (eg, methyl) Sulfonyl group, ethylsulfonyl group, etc.), amino group and the like.

The substituent represented by R ₁₃ is further an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.) , A cycloalkyl group (eg, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, etc.), a heterocyclic group (eg, pyridyl group, pyrimidyl group, oxazolyl group, Thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, etc.), arylthio group (eg, phenylthio group, Naphthylthio groups, etc.), alkenyl groups (eg For example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc. ), Halogen atoms (eg fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl groups (eg propargyl group etc.), alkylsulfonyl groups (eg methylsulfonyl group, ethylsulfonyl group etc.), arylsulfonyl groups (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.), carbamoyl group (for example, aminocal Nyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyl) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfone) Amide group, benzenesulfonamide group, etc.), cyano group, alkyloxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group For example, phenoxy group, naphthyloxy group, etc.), siloxy group, acyloxy group (eg, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group or salt thereof, aminocarbonyloxy group, amino group (eg, amino group, ethyl group) Amino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylamido Noureido 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.), carbamate group (eg methyl carbamate group, phenyl carbamate group), alkyloxyphenyl group (eg methoxyphenyl group etc.), acyloxyphenyl group (eg acetyloxyphenyl group etc.), thioureido group, carboxy A group, a salt of a carboxylic acid, a hydroxy group, a mercapto group, a nitro group, or the like may be substituted, and adjacent substituents may be bonded to form a ring.

Preferred examples of R ₁₃ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an amino group, an alkylamino group, an arylamino group, and an alkylthio group; an alkyl group, a cycloalkyl group, and an alkyl group An oxy group, an aryl group, an aryloxy group and an alkylthio group are preferred; an alkyl group, an alkyloxy group, an aryl group and an aryloxy group are more preferred; an alkyl group and an alkyloxy group are particularly preferred, and an alkyl group is most preferred. When R ₁₃ is an alkyl group, an alkyl group having 1 to 8 carbon atoms is preferable. 1-4 alkyl groups are more preferred. By using R ₁₃ as these substituents, the compatibility of the compound is improved and an optical film exhibiting a high retardation value is obtained.

In the general formula (1), R ₂₃ represents a substituent. The substituent denoted by R _23, an alkyl group (e.g., methyl group, an ethyl group, a propyl group, an isopropyl group, t- butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a trifluoromethyl group, etc. ), Cycloalkyl group (for example, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), heterocyclic group (for example, pyridyl group, pyrimidyl group, oxazolyl group) , Thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group etc.), acylamino group (eg acetylamino group, benzoylamino group etc.), alkylthio group (eg methylthio group, ethylthio group etc.), arylthio group (eg phenylthio group) , Naphthylthio group, etc.), alkenyl group ( For example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc. ), Halogen atoms (eg fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl groups (eg propargyl group etc.), alkylsulfonyl groups (eg methylsulfonyl group, ethylsulfonyl group etc.), arylsulfonyl groups (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.), carbamoyl group (for example, amino Sulfonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyl) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfone) Amide group, benzenesulfonamide group, etc.), cyano group, alkyloxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group Group (for example, phenoxy group, naphthyloxy group, etc.), siloxy group, acyloxy group (for example, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group or a salt thereof, aminocarbonyloxy group, amino group (for example, amino group) , Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino) Group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2 -Pyridyl Aminoureido 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.), carbamate group (eg, methyl carbamate group, phenyl carbamate group), alkyloxyphenyl group (eg, methoxyphenyl group, etc.), acyloxyphenyl group (eg, acetyloxyphenyl group, etc.), thioureido group, A carboxy group, a salt of a carboxylic acid, a hydroxy group, a mercapto group, a nitro group and the like are included.

The substituent represented by R ₂₃ in the general formula (1) may be further substituted with a similar group, or adjacent substituents may be bonded to form a ring.

Preferred examples of R ₂₃ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an alkylthio group, and a halogen atom; Group, cycloalkyl group, alkyloxy group, aryl group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group and halogen atom are more preferred; alkyl group, alkyloxy group, acyl group and alkoxycarbonyl group are particularly preferred preferable. By using R ₂₃ as these substituents, the compatibility of the compound is improved, and an optical film exhibiting a high retardation value with suppressed bleed-out is obtained.

  The integer represented by k3 in the general formula (1) is preferably in the range of 1 to 4, more preferably in the range of 1 to 3, and particularly preferably 1 from the viewpoint of retardation development and compatibility.

  In general formula (1), -OCO- is preferably substituted at the 3-position, 4-position, and 5-position when the binding site with the benzoxazinone skeleton is at the 1-position. More preferably, it is substituted. High retardation value is expressed by substituting at these positions.

  The integer represented by m3 in the general formula (1) is preferably in the range of 0 to 4, more preferably in the range of 0 to 3, particularly preferably 0 from the viewpoint of retardation development.

  Specific examples of the compound represented by the general formula (1) are given below, but the present invention is not limited to the following specific examples.

  The optical film of the present invention contains a cellulose ester and a compound represented by the general formula (1). In order to obtain a desired retardation, the compound represented by the general formula (1) is added to the cellulose ester. It is preferable that “Added” means dissolved or dispersed in the cellulose ester. A desired retardation cannot be obtained only by applying the compound represented by the general formula (1) only to the surface of the optical film.

  In order to obtain the desired retardation, the optical film of the present invention contains the compound represented by the general formula (1) within a range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the cellulose ester. Is preferably in the range of 1 to 15 parts by mass, more preferably in the range of 1.5 to 10 parts by mass, and particularly preferably in the range of 2 to 8 parts by mass. If it exists in this range, while providing sufficient retardation to the optical film of this invention, compatibility and bleed-out tolerance will become favorable.

  The compound represented by the general formula (1) in the present invention has a retardation value Rt (590) in the thickness direction of an optical film containing 3 parts by mass of the compound of the general formula (1) with respect to 100 parts by mass of the cellulose ester. ) Is preferably 1.1 times or more compared to the unadded cellulose ester film, more preferably in the range of 1.2 to 10 times, and in the range of 1.3 to 4 times. More preferably. By adding a compound in the above range, an optical film having excellent retardation can be provided.

  The optical film of this invention should just contain at least 1 or more types of compounds represented by the said General formula (1), and can also give retardation by using compounds other than the said General formula (1) together. it can.

<Synthesis of the compound represented by the general formula (1)>
The compound represented by the general formula (1) can be synthesized by a general method. Synthesis examples of exemplary compounds are described below.

(Synthesis of Exemplary Compound A-022)

  To a 2 L eggplant flask, 56 g of 4-hydroxybenzoic acid and 800 ml of 1N NaOH aqueous solution were added, stirred and dissolved at 40 ° C., and 50 g of acetic anhydride was added dropwise. After stirring for 1 hour, the mixture was cooled with water and 30 ml of acetic acid was added. After stirring for 1 hour, 54.5 g of intermediate A was obtained by filtering, washing with water and drying.

  To a 100 ml eggplant flask, 5.0 g of intermediate A, 3.0 ml of thionyl chloride and 0.1 ml of DMF were added and heated at 80 ° C. for 3 hours. The solvent and thionyl chloride were distilled off under reduced pressure to obtain 5.6 g of Intermediate B.

  After adding 50 g of pyridine and 4.5 g of isatoic anhydride to a 200 ml eggplant flask and heating to 50 ° C., 5.6 g of intermediate B was added dropwise. After completion of dropping, the external temperature was raised to 120 ° C. After 2 hours, the mixture was cooled to room temperature, 100 ml of water was added, and the mixture was stirred for 1 hour. 6.4 g of a crude product was obtained by drying after filtration and washing with methanol. The crude product was purified by column chromatography (developing solvent: toluene) to obtain 3.8 g of Exemplified Compound A-022. The obtained exemplary compound A-022 was identified by NMR and Mass spectrum.

  Other compounds represented by the general formula (1) can also be synthesized with reference to the disclosure of the present specification and known techniques.

<Cellulose ester>
Although the cellulose ester contained in the optical film of this invention is not specifically limited, It is preferable that it is a C2-C22 linear or branched carboxylic acid ester. The carboxylic acid constituting the ester may form a ring or an aromatic carboxylic acid. The carboxylic acid constituting the ester may have a substituent. The carboxylic acid constituting the ester is particularly preferably a lower fatty acid having 6 or less carbon atoms.

  Specific examples of preferred cellulose esters include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose mixtures with propionate or butyrate groups attached in addition to acetyl groups Examples include fatty acid esters.

  The cellulose ester preferably satisfies both the following formulas (a) and (b). In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or the degree of substitution of a mixture thereof. The degree of acyl group substitution can be measured according to ASTM-D817-96.

Formula (a) 2.0 ≦ X + Y ≦ 2.6
Formula (b) 0 ≦ Y ≦ 1.5
The cellulose ester is more preferably cellulose acetate (Y = 0) and cellulose acetate propionate (Y; propionyl group, Y> 0). Cellulose acetate propionate satisfies 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.6, and 2.0 ≦ X + Y ≦ 2.5. As cellulose acetate, 2.0 ≦ X ≦ 2.5 is preferable. The cellulose acetate most preferably used is cellulose diacetate (DAC) with 2.0 ≦ X <2.4.

  By using the above-mentioned cellulose acetate or cellulose acetate propionate, an optical film excellent in retardation, mechanical strength and environmental fluctuation can be obtained.

  In order to obtain desired optical properties, cellulose acetates having different degrees of substitution may be mixed and used. The mixing ratio of different cellulose acetates is not particularly limited, and may be in the range of 10:90 to 90:10 (mass ratio).

The number average molecular weight of the cellulose ester is preferably in the range of 6 × 10 ^{4 to} 3 × 10 ⁵ , and more preferably in the range of 7 × 10 ⁴ to 2 × 10 ⁵ , since the mechanical strength of the obtained film becomes high. The weight average molecular weight Mw and the number average molecular weight Mn of the cellulose ester can be measured using gel permeation chromatography (GPC). An example of measurement conditions is as follows, but is not limited to this, and an equivalent measurement method can be used.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products 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 Corporation) Mw = 100000 to 500 calibration curves with 13 samples are used. Thirteen samples are used at approximately equal intervals.

  The raw material cellulose of the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  Cellulose esters such as cellulose acetate and cellulose acetate propionate can be produced by known methods. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

<Compounds other than the compound represented by the general formula (1)>
In the optical film of the present invention, in addition to the cellulose ester and the compound represented by the general formula (1), a compound having a molecular weight of 10,000 or less can improve the wet heat resistance and the compatibility with the cellulose ester. It is preferable from the viewpoint of achieving both. When the compound having a molecular weight of 10,000 or less is a polymer, the weight average molecular weight is preferably 10,000 or less. A preferred molecular weight range is in the range of 100 to 10,000, more preferably in the range of 400 to 8,000.

  In particular, in order to obtain the effect of the present invention, the compound having a molecular weight of 10,000 or less is preferably contained within a range of 6 to 40 parts by mass with respect to 100 parts by mass of the cellulose ester, and is within a range of 10 to 20 parts by mass. It is more preferable to make it contain. By containing in the said range, effective control of moisture permeability and compatibility with a cellulose ester can be made compatible, and it is preferable.

  Among the compounds, at least one compound selected from the following sugar ester compounds, polyester compounds, and acrylic compounds can be highly compatible with effective control of moisture permeability and compatibility with cellulose esters. It is preferable from the viewpoint.

<Sugar ester compound>
In this invention, it is preferable to contain sugar ester compounds other than a cellulose ester. As the sugar ester compound according to the present invention, a sugar ester compound in which at least one of the pyranose structure or furanose structure is 1 to 12 and all or a part of the OH groups of the structure is esterified is used. Is preferred.

  In particular, the optical film of the present invention preferably uses a sugar ester compound having a total average substitution degree represented by the following general formula (FA) of 3.0 to 6.0.

（式中、Ｒ_１〜Ｒ_８は、各々独立に、水素原子、置換又は無置換のアルキルカルボニル基、若しくは、置換又は無置換のアリールカルボニル基を表し、Ｒ_１〜Ｒ_８は相互に同じであっても、異なっていてもよい。）
本発明に係る一般式（ＦＡ）で表される化合物の平均置換度は３．０〜６．０であることによって、透湿性の制御とセルロースエステルとの相溶性を高度に両立することができる。

(Wherein R _{1 to} R ₈ each independently represents a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ are the same as each other). Or it may be different.)
When the average substitution degree of the compound represented by the general formula (FA) according to the present invention is 3.0 to 6.0, the moisture permeability control and the compatibility with the cellulose ester can be highly compatible. .

In the present invention, the degree of substitution of the compound represented by the general formula (FA) represents the number substituted with a substituent other than hydrogen among the eight hydroxyl groups contained in the general formula (FA). among _R 1 to R ₈ of general formula (FA), it represents a number that contains a group other than hydrogen. Therefore, when all of R _{1 to} R ₈ are substituted with a substituent other than hydrogen, the degree of substitution is 8.0, which is the maximum value, and when R _{1 to} R ₈ are all hydrogen atoms, 0.0 It becomes.

  The compound having the structure represented by the general formula (FA) is difficult to synthesize a single kind of compound in which the number of hydroxyl groups and the number of OR groups are fixed. Since it is known that it becomes a compound in which several different components are mixed, it is appropriate to use the average substitution degree as the substitution degree of the general formula (FA) in the present invention. The average substitution degree can be measured from the area ratio of the chart showing the substitution degree distribution.

In General Formula (FA), R _{1 to} R ₈ represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same or different. It may be.

  Examples of the sugar as a raw material for synthesizing the sugar ester compound according to the present invention include the following, but the present invention is not limited thereto.

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

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

  There is no restriction | limiting in particular as monocarboxylic acid used at the time of the synthesis | combination of the sugar ester compound based on this invention, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, Saturated lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, and laxaric acid Examples thereof include unsaturated fatty acids such as fatty acids, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferable aromatic monocarboxylic acids include aromatic monocarboxylic acids having 1 to 5 alkyl groups or alkoxy groups introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, An aromatic monocarboxylic acid having two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid and tetralin carboxylic acid, or a derivative thereof can be mentioned, and benzoic acid is particularly preferable.

Specific examples of the sugar ester compound according to the present invention will be given below, but any one of R _{1 to} R ₈ may be the same substituent R, and the present invention is not limited thereto. .

  The sugar ester compound according to the present invention can be produced by reacting the sugar with an acylating agent (also referred to as an esterifying agent, for example, an acid halide of acetyl chloride, an anhydride such as acetic anhydride). Yes, the distribution of the degree of substitution is made by adjusting the amount of acylating agent, the timing of addition, and the esterification reaction time, but it is possible to mix sugar ester compounds with different degrees of substitution, or purely isolated compounds with different degrees of substitution. By mixing, components having a target average substitution degree and a substitution degree of 4 or less can be adjusted.

(Synthesis Example: Synthesis of Compound According to the Present Invention)

  Four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube were charged with 34.2 g (0.1 mol) of sucrose, 135.6 g (0.6 mol) of benzoic anhydride, 284. 8 g (3.6 mol) was charged, the temperature was raised while bubbling nitrogen gas through a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours.

Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer. Finally, 100 g of water is added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer is separated, and toluene is distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). The sugar ester compound 1 which is a mixture of A-1, A-2, A-3, A-4, A-5, etc. was obtained.

  When the obtained mixture was analyzed by high performance liquid chromatography mass spectrometry (HPLC-MS), A-1 was 1.2% by mass, A-2 was 13.2% by mass, and A-3 was 14.2% by mass. , A-4 was 35.4% by mass, A-5 and the like were 40.0% by mass. The average degree of substitution was 5.2.

  Similarly, 158.2 g (0.70 mol) benzoic anhydride, 146.9 g (0.65 mol), 135.6 g (0.60 mol), 124.3 g (0.55 mol) and equimolar pyridine. Were reacted to obtain sugar ester compounds having the components shown in Table 1.

  Next, by purifying a part of the obtained mixture by column chromatography using silica gel, each of A-1, A-2, A-3, A-4, A-5 and the like having a purity of 100% is obtained. Obtained.

  A-5 or the like means a mixture of all components having a substitution degree of 4 or less, that is, compounds having a substitution degree of 4, 3, 2, 1. The average substitution degree was calculated with A-5 and the like being the substitution degree 4.

In the present invention, the average degree of substitution was adjusted by adding in combination the sugar ester close to the desired degree of average substitution, isolated A-1 to A-5, and the like by the method prepared here. <Measurement conditions for HPLC-MS>
1) LC section Device: JASCO CO., LTD. Column oven (JASCO CO-965), detector (JASCO UV-970-240 nm), pump (JASCO PU-980), degasser (JASCO DG-980-50)
Column: Inertsil ODS-3 Particle size 5 μm 4.6 × 250 mm (manufactured by GL Sciences Inc.)
Column temperature: 40 ° C
Flow rate: 1 ml / min
Mobile phase: THF (1% acetic acid): H ₂ O (50:50)
Injection volume: 3 μl
2) MS unit Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)
Ionization method: Electrospray ionization (ESI) method Spray Voltage: 5 kV
Capillary temperature: 180 ° C
Vaporizer temperature: 450 ° C
<Polyester compound>
In the present invention, similarly to the sugar ester compound, it is preferable to use a polyester compound represented by the following general formula (FB) from the viewpoint of highly compatible moisture permeability control and compatibility with the cellulose ester.

Formula (FB) B- (GA) _n -GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In general formula (FB), a hydroxy group or a carboxylic acid residue represented by B, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, an alkylene dicarboxylic acid residue represented by A or It is composed of an aryl dicarboxylic acid residue and can be obtained by the same reaction as that of a normal ester compound.

  Examples of the carboxylic acid component of the polyester compound represented by the general formula (FB) include acetic acid, propionic acid, butyric acid, benzoic acid, p-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, and dimethylbenzoic acid. , Ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic acid, aliphatic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester compound represented by the general formula (FB) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pen Diol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. Glycol is used as one or a mixture of two or more.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with the cellulose ester resin.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester compound represented by the general formula (FB) include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Yes, these glycols can be used as one or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester compound represented by the general formula (FB) include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecane. There exist dicarboxylic acid etc., and these are each used as a 1 type, or 2 or more types of mixture. Examples of the aryl dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

  The polyester compound represented by the general formula (FB) preferably has a weight average molecular weight in the range of 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxy group (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy group (hydroxyl group) value is 15 mgKOH / g or less. Is.

  Although the specific compound of the polyester-type compound represented by general formula (FB) which can be used for this invention below is shown, this invention is not limited to this.

<Acrylic compound>
In the present invention, it is also preferable to use an acrylic compound suitably. Acrylic compounds also include methacrylic compounds.

  Although it does not restrict | limit especially as an acryl-type compound, The thing which a methylmethacrylate unit consists of 50-99 mass% and the total amount of the other monomer unit copolymerizable with this consists of 1-50 mass%. preferable.

  Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, and amides such as acryloylmorpholine and N, N-dimethylacrylamide. Vinyl monomers having a group, methacrylic acid ester or acrylic acid ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion, α, β-unsaturated acid such as acrylic acid, methacrylic acid, maleic acid, Unsaturated divalent carboxylic acids such as fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α and β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These may be used alone or in combination of two or more. A monomer can be used in combination.

  The acrylic compound used in the present invention may have a ring structure, specifically, a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, an N-substituted maleimide structure, and a maleic anhydride structure. And a pyran ring structure.

  Among these, from the viewpoint of thermal decomposition resistance and fluidity of the copolymer, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, vinyl monomers having an amide group such as acryloylmorpholine and dimethylacrylamide, and carbon number in the ester moiety. A methacrylic acid ester or acrylic acid ester having 5 to 22 alicyclic hydrocarbon groups, an N-substituted maleimide structure, a pyran ring structure and the like are preferable.

  Specific examples of the alkyl acrylate having 1 to 18 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, and 2-ethylhexyl acrylate. And methyl acrylate.

  Specific examples of the vinyl monomer having an amide group include acrylamide, N-methylacrylamide, N-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N-hydroxyethylacrylamide, acryloylpyrrolidine, Acryloylpiperidine, methacrylamide, N-methylmethacrylamide, N-butylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, methacryloylmorpholine, N-hydroxyethylmethacrylamide, methacryloylpyrrolidine, methacryloylpiperidine, N-vinylformamide, N-vinylacetamide, vinylpyrrolidone and the like can be mentioned. Preferably, acryloylmorpholine, N, N-dimethylacrylamide, N-butylacrylamide, vinylpyrrolidone, 2-hydroxyethyl methacrylate are used.

Specific examples of the methacrylic acid ester or acrylic acid ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion include, for example, cyclopentyl acrylate, cyclohexyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, Norbornyl acrylate, norbornyl acrylate, cyano norbornyl acrylate, isobornyl acrylate, bornyl acrylate, menthyl acrylate, fentyl acrylate, adamantyl acrylate, dimethyladamantyl acrylate, tricycloacrylate [5.2 .1.0 ^2,6 ] dec-8-yl, tricyclo [5.2.1.0 ^2,6 ] dec-4-methyl acrylate, cyclodecyl acrylate, cyclopentyl methacrylate, cyclohex methacrylate Sil, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, norbornyl methacrylate, norbornyl methyl methacrylate, cyano norbornyl methacrylate, phenyl norbornyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, methacryl Fentyl acid, adamantyl methacrylate, dimethyladamantyl methacrylate, tricyclo [5.2.1.0 ^2,6 ] deca-8-yl methacrylate, tricyclo [5.2.1.0 ^2,6 ] decamethacrylate Examples include 4-methyl, cyclodecyl methacrylate, and dicyclopentanyl methacrylate.

  Preferable examples include isobornyl methacrylate, dicyclopentanyl methacrylate, dimethyladamantyl methacrylate and the like.

  Examples of the N-substituted maleimide include N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, Ni-propylmaleimide, N-butylmaleimide, Ni-butylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, N- (4-bromophenyl) phenylmaleimide, N -(2-methylphenyl) maleimide, N- (2-ethylphenylmaleimide), N- (2-methoxyphenyl) maleimide, N- (2,4,6-trimethylphenyl) maleimide, N- (4-benzylphenyl) Maleimide, N- (2,4,6-tribromophe Le) maleimide and the like.

  Preferably, N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. are mentioned.

  Commercially available monomers can be used as they are.

  The acrylic compound preferably has a weight average molecular weight (Mw) in the range of 10,000 or less, more preferably in the range of 5000 to 10,000, from the viewpoint of achieving both moisture permeability control and compatibility with the cellulose ester. It is.

  In addition, the weight average molecular weight (Mw) of the acrylic compound according to the present invention is calculated by measurement using gel permeation chromatography (GPC) under the following measurement conditions.

Solvent: Tetrahydrofuran Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Apparatus: HLC-8220 (manufactured by Tosoh Corporation)
Flow rate: 0.6ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 samples are used. Thirteen samples are used at approximately equal intervals.

  There is no restriction | limiting in particular as a manufacturing method of an acryl-type compound, Any of well-known methods, such as suspension polymerization, emulsion polymerization, block 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. Regarding the polymerization temperature, suspension or emulsion polymerization can be carried out in the range of 30 to 100 ° C, and bulk or solution polymerization in the range of 80 to 160 ° C. 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.

<Plasticizer>
In the optical film of the present invention, a known plasticizer having a molecular weight of 10,000 or less can be used in addition to the sugar ester compound, the polyester compound, and the acrylic compound. The plasticizer is not particularly limited, but is preferably selected from polycarboxylic acid ester plasticizers, glycolate plasticizers, phthalate ester plasticizers, fatty acid ester plasticizers, and polyhydric alcohol ester plasticizers. The A suitable plasticizer for the optical film of the present invention is a polyhydric alcohol ester plasticizer.

  From the viewpoint of effectively controlling moisture permeability, preferred polyhydric alcohol ester compounds include compounds described in paragraph numbers (0218) to (0170) of JP2010-32655A. Among these, it is preferable to use pentaerythritol tetrabenzoate. Similarly, the plasticizer is preferably contained within a range of 6 to 40 parts by mass, and preferably within a range of 10 to 20 parts by mass with respect to 100 parts by mass of the cellulose ester.

<Hydrogen bonding compound>
The optical film of the present invention preferably contains a hydrogen bonding compound in order to reduce fluctuations in the retardation value Rt (590) with respect to changes in humidity.

  The hydrogen bonding compound preferably has at least a plurality of functional groups selected from hydroxy groups, amino groups, thiol groups, and carboxylic acid groups in one molecule, and has a plurality of different functional groups in one molecule. It is more preferable to have a hydroxy group and a carboxylic acid group. The compound preferably contains 1 to 2 aromatic rings as a mother nucleus, and the value obtained by dividing the number of functional groups contained in one molecule by the molecular weight of the compound is 0.01 or more. Preferably there is.

  The above effect is presumed to be because the compound binds (hydrogen bond) to the site where the cellulose ester and water molecules interact (hydrogen bonds), and acts to suppress changes in charge distribution due to desorption of water molecules. doing.

  Specific examples of the compound include compounds described in paragraph [0029] of JP 2011-227508 A, and 3-methylsalicylic acid is preferably used.

<Other components of optical film>
<Antioxidant>
In the optical film of the present invention, those generally known can be used as the antioxidant. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used.

  For example, “IrgafosXP40, IrgafosXP60 (trade name)” commercially available from BASF Japan Ltd. and the like can be mentioned.

  As the phenolic compound, those having a 2,6-dialkylphenol structure are preferable. For example, “Irganox 1076”, “Irganox 1010” commercially available from BASF Japan Ltd., and “Analyzed by ADEKA” ADEKA STAB AO-50 "and the like.

  Examples of the phosphorus compounds include “Sumizer GP” commercially available from Sumitomo Chemical Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36” and “ADK STAB 3010” commercially available from ADEKA Corporation. “IRGAFOS P-EPQ” commercially available from BASF Japan Ltd. and “GSY-P101” commercially available from Sakai Chemical Industry Co., Ltd.

  Examples of the hindered amine compound include “Tinvin 144” and “Tinvin 770” commercially available from BASF Japan, and “ADK STAB LA-52” commercially available from ADEKA.

  Examples of the sulfur compound include “Sumilizer TPL-R” and “Sumilizer TP-D” commercially available from Sumitomo Chemical Co., Ltd.

  The above double bond compounds are commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer GM” and “Sumilizer GS”. In general, it is added in an amount of 0.05 to 20% by mass, preferably 0.1 to 1% by mass, based on the resin.

<Acid supplement>
Furthermore, it is possible to contain a compound having an epoxy group as described in US Pat. No. 4,137,201 as an acid scavenger.

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

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

<Colorant>
The optical film of the present invention preferably uses a colorant. The colorant means a dye or a pigment. In the present invention, the colorant refers to a colorant having an effect of making a color tone of a liquid crystal screen a blue tone, a yellow index adjustment, or a haze reduction.

  Various dyes and pigments can be used as the colorant, but anthraquinone dyes, azo dyes, phthalocyanine pigments and the like are effective.

<Ultraviolet absorber>
Since the optical film of the present invention is preferably used on the viewing side or the backlight side of the polarizing plate, it preferably contains an ultraviolet absorber. Examples of the ultraviolet absorber include benzotriazole-based and 2-hydroxybenzophenone-based. Or ultraviolet absorbers, such as a salicylic acid phenyl ester type | system | group, are mentioned. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones.

  Of the UV absorbers, UV absorbers having a molecular weight of 400 or more are not sublimated or are not easily volatilized at a high boiling point. From the viewpoint of improving weather resistance, it is preferable.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- ( 1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, Hindered amines such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and further 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl Bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy Cis] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine The hybrid type | system | group which has the structure of a hindered amine is mentioned, These can be used individually or in combination of 2 or more types. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

  As these ultraviolet absorbers, commercially available products may be used, for example, Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. manufactured by BASF Japan, or 2, 2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; examples of commercially available products are manufactured by ADEKA Corporation LA31) can be preferably used.

  Generally, it is added in the range of 0.05 to 10% by mass, preferably 0.1 to 5% by mass with respect to the resin.

<Matting agent>
In the optical film of the present invention, it is preferable to add a matting agent in order to impart slipperiness of the film.

  The matting agent used in the present invention may be either an inorganic compound or an organic compound as long as it does not impair the transparency of the resulting film and has heat resistance during melting. These matting agents can be used alone or in combination of two or more.

  By using particles having different particle sizes and shapes (for example, acicular and spherical), both transparency and slipperiness can be made highly compatible.

  Among these, silicon dioxide, which is excellent in transparency (haze), is particularly preferably used because it has a refractive index close to that of the acrylic copolymer or cellulose ester used as a compatible resin.

  Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP- 30, Seahoster KEP-50 (manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (manufactured by Fuji Silysia), nip seal E220A (manufactured by Nippon Silica Industry), Admafine SO (manufactured by Admatechs), etc. Goods etc. can be preferably used.

  The shape of the particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, spherical shape, etc. However, the use of spherical particles is particularly preferable because the transparency of the resulting film can be improved.

  When the particle size is close to the wavelength of visible light, light is scattered and the transparency is deteriorated. Therefore, the particle size is preferably smaller than the wavelength of visible light, and more preferably ½ or less of the wavelength of visible light. . If the size of the particles is too small, the slipperiness may not be improved, so the range of 80 nm to 180 nm is particularly preferable.

  The particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.

  The particles are added in an amount of 0.05 to 10% by mass, preferably 0.1 to 5% by mass with respect to the resin.

<Acrylic particles>
For the purpose of improving the brittleness of the film, the optical film of the present invention may contain acrylic particles described in International Publication No. 2010/001668 in an amount within a range where transparency can be maintained.

  Examples of commercially available products of such a multilayer structure acrylic granular composite include, for example, “Metablene W-341” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Co., “Paraloid” manufactured by Kureha Co., Ltd., Rohm and “Acryloid” manufactured by Haas, “Staffyroid” manufactured by Gantz Kasei Kogyo Co., Ltd., Chemisnow MR-2G, MS-300X (manufactured by Soken Chemical Co., Ltd.) and “Parapet SA” manufactured by Kuraray These can be used alone or in combination of two or more.

<Hydrogen bondable solvent>
In the present invention, when a film is produced by the solution casting method, a hydrogen bonding solvent can be added to the solvent for dissolving the constituent materials of the film for the purpose of adjusting the solution viscosity. The hydrogen bonding solvent is J.I. N. As described in Israel Ativili, “Intermolecular Forces and Surface Forces” (Takeshi Kondo, Hiroyuki Oshima, Maglow Hill Publishing, 1991) and electrically negative atoms (oxygen, nitrogen, fluorine, chlorine) An organic solvent capable of producing a hydrogen atom-mediated “bond” between a hydrogen atom covalently bonded to an electronegative atom, ie, a bond having a large bond moment and containing hydrogen, such as O—H (Oxygen hydrogen bond), N—H (nitrogen hydrogen bond), and organic solvent that can arrange adjacent molecules by including F—H (fluorine hydrogen bond).

  These form a stronger hydrogen bond between the resin and the hydrogen bonding solvent than the intermolecular hydrogen bond of the acrylic copolymer, cellulose ester resin, or other resin mixture for compatibilization itself. Thus, a change in solution viscosity can be expected.

  In the solution casting method performed in the present invention, in addition to adjusting the solution viscosity with respect to the resin solution to be used, in order to reduce the peeling force at the time of film formation, a hydrogen bond is added to the solvent for dissolution. A part or all of the solvent may be used.

(Physical properties of optical film)
Hereinafter, characteristics of the optical film according to the present invention will be described.

  A haze value (turbidity) is used as an index for judging the transparency of the optical film of the present invention. In particular, in a liquid crystal display device used outdoors, since it is required that sufficient brightness and high contrast are obtained even in a bright place, the haze value is preferably 1.0% or less, and is 0.5% or less. More preferably. When used as a scattering film, the haze value may exceed the above range.

  The thickness of the optical film of the present invention is preferably in the range of 10 to 80 μm. More preferably, it is the range of 20-40 micrometers.

  The optical film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more.

  The optical film of the present invention can be particularly preferably used as a polarizing plate protective film for a large-sized liquid crystal display device or a liquid crystal display device for outdoor use as long as the above physical properties are satisfied.

(Optical film manufacturing method)
Next, an example of the method for producing an optical film of the present invention will be described, but the present invention is not limited to this.

  As the method for producing the optical film of the present invention, the usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method and the like can be used. From the standpoint of suppressing defects and suppressing optical defects such as die lines, the film forming method can be selected from a solution casting film forming method and a melt casting film forming method. It is preferable to obtain

<Solution casting film forming method>
When the optical film of the present invention is produced by a solution casting method, an organic solvent useful for forming a dope can be used without limitation as long as it dissolves cellulose ester and other compounds simultaneously.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate, and acetone can be preferably used.

  In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. When the proportion of alcohol is small, cellulose ester and other compounds dissolve in non-chlorine organic solvents. There is also a role to promote.

  In particular, a dope composition in which cellulose ester and other compounds are dissolved at least 15 to 45 mass% in total in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. Preferably there is.

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

  Hereinafter, the preferable film forming method of the optical film of the present invention will be described.

1) Dissolving step In an organic solvent mainly composed of a good solvent for cellulose ester, the cellulose ester in a dissolution vessel, and optionally dissolving other compounds while stirring to form a dope, or the cellulose ester solution, In some cases, other compound solutions are mixed to form a dope which is a main solution.

  For dissolving cellulose ester and other compounds, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544 and JP-A-9- Various dissolution methods can be used such as a method performed by a cooling dissolution method as described in JP-A-95557 or JP-A-9-95538, and a method performed at high pressure as described in JP-A No. 11-21379. In particular, a method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent is preferable.

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

  It is preferable to use a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml.

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

  FIG. 1 is a diagram schematically showing an example of a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention.

  Large agglomerates are removed from the charging kettle 41 by the filter 44 and fed to the stock kettle 42. Thereafter, various additive solutions are added from the stock kettle 42 to the main dope dissolving kettle 1.

  Thereafter, the main dope is filtered by the main filter 3, and an ultraviolet absorbent additive solution is added in-line from 16 to this.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material.

  The return material is a product obtained by finely pulverizing the optical film, which is generated when the optical film is formed, and is obtained by cutting off both sides of the film, or by using an optical film original that has been speculated out due to scratches, etc. .

  Moreover, as a raw material of resin used for dope preparation, what pelletized cellulose ester and other compounds previously can be used preferably.

2) Casting process An endless metal belt 31 such as a stainless steel belt or a rotating metal drum that feeds the dope to a pressure die 30 through a liquid feed pump (for example, a pressurized metering gear pump) and transfers it indefinitely. This is a step of casting a dope from a pressure die slit to a casting position on a metal support.

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

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

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

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

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

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

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

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

Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 140 ° C. for 1 hour.

  The peeling tension at the time of peeling the metal support and the film is usually within a range of 196 to 245 N / m. However, when wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. .

  In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.

5) Drying and stretching step After peeling, a drying device 35 that alternately passes the web through rollers arranged in the drying device and / or a tenter stretching device 34 that clips and transports both ends of the web with clips are used. And dry the web.

  Generally, the drying means blows hot air on both sides of the web, but there is also a means for heating by applying microwaves instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout, the drying is generally carried out in the range of 40-250 ° C. It is particularly preferable to dry within the range of 40 to 200 ° C.

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

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

  The stretching operation may be performed in multiple stages, and it is particularly preferable to perform biaxial stretching in the casting direction and the width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. The draw ratio is 1.1 to 9 times, preferably 1.2 to 5 times, by adding the casting direction and the width direction.

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

-Stretch in the casting direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferable draw ratio of simultaneous biaxial stretching is in the range of 1.01 to 1.5 times in both the width direction and the longitudinal direction.

  When the tenter is used, the residual solvent amount of the web is preferably in the range of 20 to 100% by mass at the start of the tenter, and drying is performed while the tenter is applied until the residual solvent amount of the web becomes 10% by mass or less. Is more preferable, and more preferably 5% by mass or less.

  The drying temperature when performing the tenter is preferably in the range of 30 to 160 ° C, more preferably in the range of 50 to 150 ° C.

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

6) Winding step This is a step of winding the optical film by the winder 37 after the residual solvent amount in the web is 2% by mass or less, and the dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. A film having good properties can be obtained. In particular, it is preferable to wind up in the range of 0.00 to 0.10% by mass.

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

  The optical film of the present invention is preferably a long film. Specifically, the optical film has a thickness of about 100 m to 10000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a film is 1-4m, and it is more preferable that it is 1.4-3m.

<Melt casting method>
The optical film of the present invention can also be formed by a melt casting method.

  The melt film-forming method refers to a method in which a composition containing additives such as a resin and a plasticizer is heated and melted to a temperature exhibiting fluidity, and then a melt containing fluid cellulose acetate is cast.

  The molding method for heating and melting can be classified in detail into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these molding methods, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. The plurality of raw materials used in the melt extrusion method are usually preferably kneaded in advance and pelletized.

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

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  It is preferable that the extruder can be pelletized so as to suppress the shearing force and prevent the resin from deteriorating (molecular weight reduction, coloring, gel formation, etc.) and processing at as low a temperature as possible. For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

  The melting temperature when extruding the above pellets using a single-screw or twin-screw type extruder is set to a temperature range of 200 to 300 ° C., filtered through a leaf disk type filter, etc. A film is cast from the die, the film is nipped by a cooling roller and an elastic touch roller, and solidified on the cooling roller.

  A method of preventing oxidative decomposition or the like under vacuum or reduced pressure or in an inert gas atmosphere when introducing from the supply hopper to the extruder is also preferable.

  The extrusion flow rate is preferably performed stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is made by compressing the intricately intertwined state of the stainless steel fiber body and sintering and integrating the contact points. The density changes depending on the thickness of the fiber and the amount of compression, and the filtration accuracy Can be adjusted.

  Additives such as plasticizers and particles may be mixed with the resin in advance, or 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.

  When the film is nipped by the cooling roller and the elastic touch roller, the film temperature on the touch roller side is preferably in the temperature range of Tg to Tg + 110 ° C. of the film. A known roller can be used as the roller having an elastic surface used for such a purpose.

  The elastic touch roller is also referred to as a pinching rotator. A commercially available elastic touch roller can also be used.

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

  Moreover, it is preferable that the film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roller.

  As a stretching method, a known roller stretching machine or tenter can be preferably used. The stretching temperature is usually preferably performed in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  Before winding, the end may be slit and cut to the width to be the product, and knurling (embossing) may be applied to both ends to prevent sticking and scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. Note that the clip holding portions at both ends of the film are usually cut off because the film is deformed and cannot be used as a product. If the material has not deteriorated due to heat, it is reused after recovery.

<Configuration of polarizing plate and liquid crystal display device>
The configuration of the polarizing plate and the liquid crystal display device provided with the optical film of the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a polarizing plate provided with the optical film of the present invention and a liquid crystal display device provided with the polarizing plate.

  In the polarizing plate 101A according to the present invention, at least a protective film 102, an active energy ray-curable adhesive 103A, and a polarizer 104 are laminated in this order, and further, the surface on which the protective film is disposed. It is a preferable aspect that the active energy ray-curable adhesive 103B and the optical film 105 of the present invention are laminated on the opposite polarizer surface.

  Further, a functional layer 106 such as an antiglare layer, an antireflection layer, an antifouling layer, and a hard coat layer may be provided on the outer side (outermost surface portion) of the protective film 102 as necessary. .

  The optical film 105 of the polarizing plate 101A is bonded to the liquid crystal cell 107 via an adhesive or the like, and the liquid crystal cell surface (backlight side: in the figure) on the opposite side of the bonded surface of the polarizing plate 101A and the liquid crystal cell 107. It is preferable that the optical film 105 of the present invention of the polarizing plate 101B having the same configuration as the polarizing plate 101A is bonded to form the liquid crystal display device 108.

<Active energy ray-curable adhesive>
Regarding the adhesion between the optical film of the present invention and the polarizer, a polyvinyl alcohol-based adhesive, an active energy ray-curable adhesive, or the like can be used, and in particular, the use of the following active energy ray-curable adhesive has moisture permeability. It is preferable because it can be controlled effectively. The active energy ray-curable adhesive includes a cationic polymerization type and a radical polymerization type.

  Preferable examples of the active energy ray-curable adhesive that can be suitably used in the present invention include active energy ray-curable adhesive compositions containing the following components (α) to (δ).

(Α) Cationic polymerizable compound (β) Photocationic polymerization initiator (γ) Photosensitizer exhibiting maximum absorption for light having a wavelength longer than 380 nm (δ) Naphthalene photosensitizer (cationic polymerizable compound (α ))
The cationic polymerizable compound (α), which is a main component of the active energy ray-curable adhesive composition and serves as a component that imparts adhesive force by polymerization and curing, may be any compound that cures by cationic polymerization. It is preferable to include an epoxy compound having two epoxy groups. The epoxy compound includes an aromatic epoxy compound having an aromatic ring in the molecule, an alicyclic epoxy compound having at least two epoxy groups in the molecule, and at least one of which is bonded to the alicyclic ring. A fatty acid that does not have an aromatic ring in the molecule and one carbon atom of the ring containing the two carbon atoms to which it is bonded (usually an oxirane ring) is bonded to another aliphatic carbon atom Group epoxy compounds. The active energy ray-curable adhesive composition used in the present invention is preferably an epoxy resin not containing an aromatic ring and an alicyclic epoxy compound as a main component, particularly as the cationic polymerizable compound (α). If a cationically polymerizable compound having an alicyclic epoxy compound as a main component is used, a cured product having a high storage elastic modulus is provided, and an optical film and a polarizer are bonded via the cured product (adhesive layer). In this case, the polarizer is difficult to break.

  The alicyclic epoxy compound has at least two epoxy groups in the molecule, and at least one of them is bonded to the alicyclic ring. Here, the epoxy group bonded to the alicyclic ring is, as shown in the following formula (ep), two bonds in which two bonds of the epoxy group (—O—) constitute the alicyclic ring. Each of the carbon atoms (usually adjacent carbon atoms). In the following general formula (ep), m represents an integer of 2 to 5.

A compound in which a group in which one or more hydrogen atoms in (CH ₂ ) _m in the general formula (ep) are removed is bonded to another chemical structure can be an alicyclic epoxy compound. Hydrogen constituting the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Of these, compounds having an epoxycyclopentane ring (m = 3 in the above formula (ep)) or an epoxycyclohexane ring (m = 4 in the above formula (ep)) are preferable.

  Among the alicyclic epoxy compounds, any of the following compounds (ep-1) to (ep-11) is more preferable because they are easily available and have a large effect of increasing the storage elastic modulus of the cured product.

In said formula, R < ³ > -R < ²⁴ > represents a hydrogen atom or a C1-C6 alkyl group each independently, and when R < ³ > -R < ²⁴ > is an alkyl group, the position couple | bonded with an alicyclic ring is 1. It is an arbitrary number of the first to sixth positions. The alkyl group having 1 to 6 carbon atoms may be a straight chain, may have a branch, or may have an alicyclic ring. Y ⁸ represents an oxygen atom or an alkanediyl group having 1 to 20 carbon atoms. Y ^{1 to} Y ⁷ each independently represents a straight chain, may have a branch, and represents an alkanediyl group having 1 to 20 carbon atoms which may have an alicyclic ring. n, p, q and r each independently represents a number of 0 to 20.

Among the compounds represented by the above formulas (ep-1) to (ep-11), the alicyclic diepoxy compound represented by the formula (ep-2) is preferable because it is easily available. The alicyclic diepoxy compound of the formula (ep-2) is composed of 3,4-epoxycyclohexylmethanol (an alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring) and 3,4-epoxycyclohexane. An ester compound with a carboxylic acid (an alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring). Specific examples of such ester compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (a compound in which R ⁵ = R ⁶ = H and n = 0 in the formula (ep-2)) 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate (in the formula (ep-2), R ⁵ = 6-methyl, R ⁶ = 6-methyl, n = Compound which is 0) and the like.

  In addition, it is effective to use an alicyclic epoxy compound in combination with an epoxy resin having substantially no alicyclic epoxy group. If a cation-polymerizable compound containing an alicyclic epoxy compound as the main component and an epoxy resin substantially free of an alicyclic epoxy group is used as a cationically polymerizable compound, the cured product has a high storage elastic modulus. However, the adhesion between the polarizer and the optical film can be further enhanced. As used herein, an epoxy resin having substantially no alicyclic epoxy group means that one carbon atom of a ring (usually an oxirane ring) containing an epoxy group and two carbon atoms to which the epoxy group is bonded in the molecule. A compound bonded to another aliphatic carbon atom. Examples thereof include polyglycidyl ether of polyhydric alcohol (phenol). Among these, a diglycidyl ether compound represented by the following general formula (ge) is preferable because it is easily available and has a great effect of improving the adhesion between the polarizer and the optical film.

〔式中、Ｘは直接結合、メチレン基、炭素原子数１〜４のアルキリデン基、脂環式炭化水素基、Ｏ、Ｓ、ＳＯ_２、ＳＳ、ＳＯ、ＣＯ、ＯＣＯ又は下記式（ｇｅ−１）〜（ｇｅ−３）で表される３種の置換基からなる群から選ばれる置換基を表し、アルキリデン基はハロゲン原子で置換されていてもよい。〕

[Wherein, X represents a direct bond, a methylene group, an alkylidene group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group, O, S, SO ₂ , SS, SO, CO, OCO, or the following formula (ge-1 )-(Ge-3) represents a substituent selected from the group consisting of three types of substituents, and the alkylidene group may be substituted with a halogen atom. ]

In the formula (ge-1), R ²⁵ and R ²⁶ may each independently be substituted with a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group. Represents a cycloalkyl group having 3 to 10 carbon atoms which may be substituted by a phenyl group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group, and R ²⁵ and R ²⁶ may be linked to each other to form a ring. Good.

  In the formula (ge-2), A and D are each independently an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, or 6 carbon atoms which may be substituted with a halogen atom. Represents an aryl group having ˜20, an arylalkyl group having 7 to 20 carbon atoms which may be substituted with a halogen atom, a heterocyclic group having 2 to 20 carbon atoms which may be substituted with a halogen atom, or a halogen atom; The methylene group in the alkyl group, aryl group or arylalkyl group may be interrupted by an unsaturated bond, -O- or -S-. a represents a number of 0 to 4, and d represents a number of 0 to 4.

  Examples of the diglycidyl ether compound represented by the general formula (ge) include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Polyfunctional epoxy resin such as glycidyl ether of methane, glycidyl ether of tetrahydroxybenzophenone, epoxidized polyvinylphenol; polyglycidyl ether of aliphatic polyhydric alcohol; polyglycidyl ether of alkylene oxide adduct of aliphatic polyhydric alcohol A diglycidyl ether of alkylene glycol, and the like. Among them, a polyglycidyl ether of an aliphatic polyhydric alcohol is preferable.

  Examples of the aliphatic polyhydric alcohol include those having 2 to 20 carbon atoms. More specifically, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl -2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2 -Aliphatic diols such as methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol; cyclohexanedi Cycloaliphatic diols such as butanol, cyclohexanediol, hydrogenated bisphenol A, hydrogenated bisphenol F; trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, polyglycerin, pentaerythritol, dipentaerythritol, tetramethylol Examples include trivalent or higher polyols such as propane.

  When using together an alicyclic epoxy compound and an epoxy resin substantially free of an alicyclic epoxy group, the blending ratio of both is 50 to 50 based on the total amount of the cationically polymerizable compound. It is preferable that 95% by mass and an epoxy resin substantially not having an alicyclic epoxy group be 5% by mass or more. By blending 50% by mass or more of the alicyclic epoxy compound in the whole cationic polymerizable compound, the storage elastic modulus at 80 ° C. of the cured product becomes 1000 MPa or more, and through such a cured product (adhesive layer) In the polarizing plate in which the polarizer and the optical film are bonded, the polarizer is difficult to break. Moreover, the adhesiveness of a polarizer and an optical film improves by mix | blending 5 mass% or more of epoxy resins which do not have an alicyclic epoxy group substantially with respect to the whole cationically polymerizable compound. The amount of the epoxy resin having substantially no alicyclic epoxy group is 50 based on the total amount of the cation polymerizable compound when the cation polymerizable compound is a two-component system with the alicyclic epoxy compound. Although it is allowed up to mass%, if the amount is excessive, the storage modulus of the cured product is lowered and the polarizer is easily broken, so that it is 45 mass% or less based on the total amount of the cationically polymerizable compound. It is preferable to do this.

  As the cationic polymerizable compound (α) constituting the active energy ray-curable adhesive composition according to the present invention, an alicyclic epoxy compound and an epoxy resin substantially free of an alicyclic epoxy group as described above When these are used in combination, other cationically polymerizable compounds may be included in addition to these in the range in which each amount is as described above. Examples of other cationic polymerizable compounds include epoxy compounds other than formulas (ep-1) to (ep-11) and general formula (ge), oxetane compounds, and the like.

  Epoxy compounds other than formulas (ep-1) to (ep-11) and formula (ge) include at least one alicyclic ring in a molecule other than formulas (ep-1) to (ep-11). An alicyclic epoxy compound having an epoxy group to be bonded, an aliphatic epoxy compound having an oxirane ring bonded to an aliphatic carbon atom other than the formula (ge), an aromatic epoxy compound having an aromatic ring and an epoxy group in the molecule, aromatic There are hydrogenated epoxy compounds in which aromatic rings in group epoxy compounds are hydrogenated.

  Examples of alicyclic epoxy compounds having an epoxy group bonded to at least one alicyclic ring in a molecule other than those represented by formulas (ep-1) to (ep-11) include 4-vinylcyclohexene diepoxide, 2: diepoxides of vinylcyclohexenes such as 8,8,9-diepoxy limonene.

  Examples of the aliphatic epoxy compound having an oxirane ring bonded to an aliphatic carbon atom other than the general formula (ge) include triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, and diglycidyl ether of polyethylene glycol.

  The aromatic epoxy compound having an aromatic ring and an epoxy group in the molecule can be a glycidyl ether of an aromatic polyhydroxy compound having at least two phenolic hydroxy groups (hydroxyl groups) in the molecule. Bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, phenol novolac resin glycidyl ether, and the like.

  A hydrogenated epoxy compound having an aromatic ring hydrogenated in an aromatic epoxy compound catalyzes an aromatic polyhydroxy compound having at least two phenolic hydroxy groups in a molecule as a raw material of the aromatic epoxy compound. The hydrogenated polyhydroxy compound obtained by selectively performing a hydrogenation reaction under pressure in the presence of glycidyl ether can be obtained. Specific examples include diglycidyl ether of hydrogenated bisphenol A, diglycidyl ether of hydrogenated bisphenol F, diglycidyl ether of hydrogenated bisphenol S, and the like.

  Among the epoxy compounds other than these formulas (ep-1) to (ep-11) and the general formula (ge), they have an epoxy group bonded to an alicyclic ring and are classified as the alicyclic epoxy compounds defined above. When the compound to be blended is added, the sum of the alicyclic epoxy compounds represented by the formulas (ep-1) to (ep-11) does not exceed 95% by mass based on the total amount of the cationically polymerizable compounds. Used in a range.

  An oxetane compound that can be any cationically polymerizable compound is a compound having a 4-membered ring ether (oxetanyl group) in the molecule. Specific examples thereof include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [ (3-ethyl-3-oxetanyl) methyl] ether, bis [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- ( (Cyclohexyloxymethyl) oxetane, phenol novolac oxetane, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, oxetanylsilsesquioxane, oxetanyl silicate and the like.

  By blending the oxetane compound at a ratio of 30% by mass or less based on the total amount of the cationic polymerizable compound, an effect of improving curability is expected compared to the case where only the epoxy compound is used as the cationic polymerizable compound. There are things you can do.

(Photocationic polymerization initiator (β))
In the present invention, the cationically polymerizable compound as described above is cationically polymerized by irradiation with active energy rays and cured to form an adhesive layer. Therefore, the active energy ray-curable adhesive composition includes a photocation. It is preferable to blend a polymerization initiator (β).

  The cationic photopolymerization initiator generates a cationic species or a Lewis acid upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of the cationic polymerizable compound (α). It is. Since the cationic photopolymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with the cationically polymerizable compound (α). Examples of compounds that generate cation species and Lewis acids upon irradiation with active energy rays include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes, and the like.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfoni O] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfo Nio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate, and the like.

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) tris ( (Trifluoromethylsulfonyl) methanide and the like.

  These cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in the wavelength region near 300 nm, and thus can provide a cured product having excellent curability and good mechanical strength and adhesive strength. .

  The compounding quantity of a photocationic polymerization initiator ((beta)) shall be in the range of 1-10 mass parts with respect to 100 mass parts of the whole cationic polymerizable compound ((alpha)). By blending 1 part by mass or more of the cationic photopolymerization initiator per 100 parts by mass of the cationic polymerizable compound (α), the cationic polymerizable compound (α) can be sufficiently cured, and the resulting polarizing plate has high mechanical strength. And give adhesive strength. On the other hand, when the amount is increased, the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases and the durability performance of the polarizing plate may be lowered. ) Is 10 parts by mass or less per 100 parts by mass of the cationically polymerizable compound (α).

  The amount of the cationic photopolymerization initiator (β) is preferably 2 parts by mass or more and preferably 6 parts by mass or less per 100 parts by mass of the cationic polymerizable compound (α).

(Photosensitizer (γ))
The active energy ray-curable adhesive composition according to the present invention can be used for light having a wavelength longer than 380 nm in addition to the cationic polymerizable compound (α) and the cationic photopolymerization initiator (β) including the epoxy compound as described above. Contains a photosensitizer (γ) exhibiting maximum absorption. The cationic photopolymerization initiator (β) exhibits maximum absorption at a wavelength near or shorter than 300 nm, generates a cationic species or a Lewis acid in response to light having a wavelength near the wavelength, and generates a cationic polymerizable compound (α ) Is initiated, but a photosensitizer (γ) that exhibits maximum absorption in light having a wavelength longer than 380 nm is blended so as to be sensitive to light having a longer wavelength than that.

  As such a photosensitizer (γ), an anthracene compound represented by the following general formula (at) is advantageously used.

〔式中、Ｒ_５及びＲ_６は、それぞれ独立に炭素数１〜６のアルキル基又は炭素数２〜１２のアルコキシアルキル基を表す。Ｒ_７は、水素原子又は炭素数１〜６のアルキル基を表す。〕
一般式（ａｔ）で示されるアントラセン系化合物の具体例としては、９，１０−ジメトキシアントラセン、９，１０−ジエトキシアントラセン、９，１０−ジプロポキシアントラセン、９，１０−ジイソプロポキシアントラセン、９，１０−ジブトキシアントラセン、９，１０−ジペンチルオキシアントラセン、９，１０−ジヘキシルオキシアントラセン、９，１０−ビス（２−メトキシエトキシ）アントラセン、９，１０−ビス（２−エトキシエトキシ）アントラセン、９，１０−ビス（２−ブトキシエトキシ）アントラセン、９，１０−ビス（３−ブトキシプロポキシ）アントラセン、２−メチル又は２−エチル−９，１０−ジメトキシアントラセン、２−メチル又は２−エチル−９，１０−ジエトキシアントラセン、２−メチル又は２−エチル−９，１０−ジプロポキシアントラセン、２−メチル又は２−エチル−９，１０−ジイソプロポキシアントラセン、２−メチル又は２−エチル−９，１０−ジブトキシアントラセン、２−メチル又は２−エチル−９，１０−ジペンチルオキシアントラセン、２−メチル又は２−エチル−９，１０−ジヘキシルオキシアントラセン等が挙げられる。

[Wherein, R ₅ and R ₆ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms. R ₇ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ]
Specific examples of the anthracene compound represented by the general formula (at) include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, 9 , 10-dibutoxyanthracene, 9,10-dipentyloxyanthracene, 9,10-dihexyloxyanthracene, 9,10-bis (2-methoxyethoxy) anthracene, 9,10-bis (2-ethoxyethoxy) anthracene, 9 , 10-bis (2-butoxyethoxy) anthracene, 9,10-bis (3-butoxypropoxy) anthracene, 2-methyl or 2-ethyl-9,10-dimethoxyanthracene, 2-methyl or 2-ethyl-9, 10-diethoxyanthracene, 2-methyl or 2 Ethyl-9,10-dipropoxyanthracene, 2-methyl or 2-ethyl-9,10-diisopropoxyanthracene, 2-methyl or 2-ethyl-9,10-dibutoxyanthracene, 2-methyl or 2-ethyl Examples include -9,10-dipentyloxyanthracene, 2-methyl or 2-ethyl-9,10-dihexyloxyanthracene.

  By incorporating the photosensitizer (γ) as described above into the active energy ray-curable adhesive composition, the curability of the active energy ray-curable adhesive composition is improved compared to the case where it is not incorporated. To do. By setting the blending amount of the photosensitizer (γ) to 100 parts by mass of the cationic polymerizable compound (α) constituting the active energy ray-curable adhesive composition to be 0.1 parts by mass or more, curability is improved. The improvement effect is manifested. On the other hand, when the blending amount of the photosensitizer (γ) increases, problems such as precipitation during low-temperature storage occur, so the blending amount of 2 parts by weight or less with respect to 100 parts by weight of the cationic polymerizable compound (α) To do. From the viewpoint of maintaining the neutral gray of the polarizing plate, it is advantageous to reduce the amount of the photosensitizer (γ) in a range in which the adhesiveness between the polarizer and the optical film is maintained appropriately. For example, with respect to 100 parts by mass of the cationically polymerizable compound (α), the amount of the photosensitizer (γ) is 0.1 to 0.5 parts by mass, and further 0.1 to 0.3 parts by mass. Is preferred.

(Photosensitizer (δ))
The active energy ray-curable adhesive composition according to the present invention includes the above-described cationic polymerizable compound (α) containing an epoxy compound, a photo cationic polymerization initiator (β), and a photosensitizer (γ), A naphthalene-based photosensitization aid (δ) represented by the general formula (nf) can be contained.

〔式中、Ｒ^１及びＲ^２はそれぞれ、炭素数１〜６のアルキル基である。〕
ナフタレン系光増感助剤（δ）の具体例としては、１，４−ジメトキシナフタレン、１−エトキシ−４−メトキシナフタレン、１，４−ジエトキシナフタレン、１，４−ジプロポキシナフタレン、１，４−ジブトキシナフタレン等が挙げられる。

[Wherein, R ¹ and R ² are each an alkyl group having 1 to 6 carbon atoms. ]
Specific examples of the naphthalene photosensitizing aid (δ) include 1,4-dimethoxynaphthalene, 1-ethoxy-4-methoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dipropoxynaphthalene, 1, 4-dibutoxynaphthalene etc. are mentioned.

  In the active energy ray-curable adhesive composition according to the present invention, by adding the naphthalene photosensitizing aid (δ), the active energy ray-curable adhesive composition is compared with the case where it is not added. Curability is improved. Curing is achieved by setting the blending amount of the naphthalene photosensitizer (δ) to 0.1 parts by mass or more with respect to 100 parts by mass of the cationic polymerizable compound (α) constituting the active energy ray-curable adhesive composition. The effect of improving the properties is manifested. On the other hand, if the amount of the naphthalene-based photosensitization aid (δ) increases, problems such as precipitation during low-temperature storage occur, and therefore the amount is 10 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable compound (α). The blending amount. Preferably, the blending amount is 5 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable compound (α).

  Furthermore, the active energy ray-curable adhesive composition according to the present invention can contain an additive component as another component that is an optional component as long as the effects of the present invention are not impaired. As additive components, in addition to the above-mentioned photocationic polymerization initiator and photosensitizer (γ), photosensitizers other than the photosensitizer (γ), thermal cationic polymerization initiators, polyols, ion trapping agents , Antioxidants, light stabilizers, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, leveling agents, dyes, organic solvents, and the like.

  When the additive component is contained, the amount of the additive component used is preferably 1000 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable compound (α). When the amount used is 1000 parts by mass or less, a cationically polymerizable compound (α), a photocationic polymerization initiator (β), a photointensifier which are essential components of the active energy ray-curable adhesive composition that can be used in the present invention. The combination of the sensitizer (γ) and the photosensitization aid (δ) can exhibit the effects of improving storage stability, preventing discoloration, improving the curing speed, and ensuring good adhesion.

  As a preferable example of the active energy ray-curable adhesive that can be suitably used in the present invention, an N-substituted amide monomer having a hydroxy group is contained as a curable component of the active energy ray-curable adhesive. The hydroxy group may have at least one substituent bonded to the nitrogen atom (N) forming the amide group, and may have two or more. As the N-substituted amide monomer having a hydroxy group, either monofunctional or bifunctional or more can be used. Moreover, the N-substituted amide monomer which has a hydroxyl group can select 1 type, or can be used in combination of 2 or more type.

  The N-substituted amide monomer having a hydroxy group exhibits good adhesiveness even to a polarizer having a low moisture content or an optical film using a material having low moisture permeability. In particular, the following monomers exhibit good adhesion. For example, N-substituted amide monomers include N-hydroxyethyl (meth) acrylamide, N- (2,2-dimethoxy-1-hydroxyethyl)-(meth) acrylamide, N-hydroxymethyl (meth) acrylamide, p -Hydroxyphenyl (meth) acrylamide, N, N '-(1,2-dihydroxyethylene) bis (meth) acrylamide and the like. Among these, N-hydroxyethyl (meth) acrylamide is preferable. In addition, (meth) acrylamide means an acrylamide group and / or a methacrylamide group.

  In addition to the N-substituted amide monomer having a hydroxy group, the curable component may contain other monomers. Examples of other monomers that can be used as the curable component include compounds having a (meth) acryloyl group, compounds having a vinyl group, and the like. As the other monomer used as the curable component, either monofunctional or bifunctional or more can be used. These curable components may be used alone or in combination of two or more.

  As other monomers used as the curable component, for example, N-substituted amide monomers other than N-substituted amide monomers having a hydroxy group are preferably used. The N-substituted amide monomer is represented by the following general formula (N).

General formula (N)
_{CH 2 = C (R 1)} -CONR 2 (R 3)
In the general formula (N), R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydrogen atom, a straight chain having 1 to 4 carbon atoms which may have a mercapto group, an amino group or a quaternary ammonium group. Alternatively, it represents a branched alkyl group, and R ₃ represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. However, the case where R ₂ and R ₃ are hydrogen atoms at the same time is excluded. R ₂ and R ₃ are bonded to form a 5-membered ring or a 6-membered ring that may contain an oxygen atom.

In the general formula (N), examples of the linear or branched alkyl group having 1 to 4 carbon atoms in R ₂ or R ₃ include a methyl group, an ethyl group, an isopropyl group, and a t-butyl group. Examples of the alkyl group having an amino group include an aminomethyl group and an aminoethyl group. Moreover, when R < ₂ > and R < ₃ > _couple | bond together and form the 5-membered ring or 6-membered ring which may contain an oxygen atom, it has a heterocyclic ring which has nitrogen. Examples of the heterocyclic ring include morpholine ring, piperidine ring, pyrrolidine ring, piperazine ring and the like.

  Specific examples of the N-substituted amide monomer include, for example, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropylacrylamide, N- Butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaapt Examples include methyl (meth) acrylamide and mercaptoethyl (meth) acrylamide. Examples of the heterocyclic-containing monomer having a heterocyclic ring include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. These N-substituted amide monomers can be used singly or in combination of two or more.

  When the N-substituted amide monomer having a hydroxy group and the N-substituted amide monomer represented by the general formula (N) are used in combination as a curable component, durability, coatability, adhesion From the viewpoint of sex, a combination of N-hydroxyethyl (meth) acrylamide and N-acryloylmorpholine is preferred. Moreover, in the case of the said combination, the ratio of N-hydroxyethyl (meth) acrylamide with respect to the total amount of N-hydroxyethyl (meth) acrylamide and N-acryloyl morpholine is 40 mass% or more, and it has favorable adhesiveness. It is preferable in obtaining. As for the said ratio, 40-95 mass% is more preferable, Furthermore, it is preferable that it is 60-90 mass%.

  Moreover, as a monomer which can be used in combination with an N-substituted amide monomer having a hydroxy group as a curable component, in addition to the above, as a compound having a (meth) acryloyl group, for example, various epoxy (meth) acrylates and urethanes Examples include (meth) acrylate, polyester (meth) acrylate, and various (meth) acrylate monomers. Among these, epoxy (meth) acrylates, particularly monofunctional (meth) acrylates having an aromatic ring and a hydroxy group are preferably used.

  As the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group, various monofunctional (meth) acrylates having an aromatic ring and a hydroxy group can be used. The hydroxy group may be present as a substituent on the aromatic ring, but is preferably present as an organic group that binds the aromatic ring and the (meth) acrylate (bonded to a hydrocarbon group, particularly an alkylene group). .

  Examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include a reaction product of a monofunctional epoxy compound having an aromatic ring and (meth) acrylic acid. Examples of the monofunctional epoxy compound having an aromatic ring include phenyl glycidyl ether, t-butylphenyl glycidyl ether, and phenyl polyethylene glycol glycidyl ether. Specific examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include, for example, 2-hydroxy-3-phenoxypropyl (meth) acrylate and 2-hydroxy-3-t-butylphenoxypropyl (meth). Examples thereof include acrylate and 2-hydroxy-3-phenyl polyethylene glycol propyl (meth) acrylate.

  Moreover, a carboxy group monomer is mentioned as a compound which has a (meth) acryloyl group. Carboxy group monomers are also preferred from the viewpoint of adhesiveness. Examples of the carboxy group monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and the like. Of these, acrylic acid is preferred.

  In addition to the above, compounds having a (meth) acryloyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl. Alkyl (meth) acrylates having 1 to 12 carbon atoms such as (meth) acrylate and lauryl (meth) acrylate; (meth) acrylic acid alkoxyalkyl systems such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl Monomer; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxy (meth) acrylate Octyl, (meth) a Hydroxy group-containing monomers such as 10-hydroxydecyl laurate, 12-hydroxy lauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate; Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; Caprolactone adduct of acrylic acid; styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene Examples thereof include sulfonic acid group-containing monomers such as sulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate. (Meth) acrylamide; maleimide, N-cyclohexylmaleimide, N-phenylmaleimide and the like; aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, ( (Meth) acrylic acid alkylaminoalkyl monomers such as meth) acrylic acid t-butylaminoethyl, 3- (3-pyridyl) propyl (meth) acrylate; N- (meth) acryloyloxymethylene succinimide and N- (meth) Examples thereof include nitrogen-containing monomers such as succinimide monomers such as acryloyl-6-oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide.

  In addition to the above curable components, bifunctional or higher curable components can be used. The bifunctional or higher curable component is preferably a bifunctional or higher (meth) acrylate, particularly a bifunctional or higher epoxy (meth) acrylate. The bifunctional or higher functional epoxy (meth) acrylate is obtained by reacting a polyfunctional epoxy compound with (meth) acrylic acid. Various examples of the polyfunctional epoxy compound can be exemplified. Examples of the polyfunctional epoxy compound include aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

  Examples of the aromatic epoxy resin include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde Examples include novolak-type epoxy resins such as phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  Examples of the alicyclic epoxy resin include hydrogenated aromatic epoxy resins, cyclohexane-based, cyclohexylmethyl ester-based, cicyclohexylmethyl ether-based, spiro-based, and tricyclodecane-based epoxy resins.

  Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene. Polyethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as glycol diglycidyl ether, ethylene glycol, propylene glycol, and glycerin Examples thereof include glycidyl ether.

  The epoxy equivalent of the epoxy resin is usually in the range of 30 to 3000 g / equivalent, preferably 50 to 1500 g / equivalent.

  The bifunctional or higher epoxy (meth) acrylate is preferably an epoxy (meth) acrylate of an aliphatic epoxy resin, particularly preferably an epoxy (meth) acrylate of a bifunctional aliphatic epoxy resin.

  As the curable component in the active energy ray-curable adhesive, an N-substituted amide monomer having a hydroxy group is used, and the monomer used in combination with this is an N-substituted amide represented by the general formula (1). System monomers are preferred. In addition, when using together the monofunctional (meth) acrylate which has an aromatic ring and a hydroxy group as a sclerosing | hardenable component, it is 0-50 mass% with respect to the ratio of the N-substituted amide type monomer which has a hydroxy group, 1 It is preferable to be within the range of ˜40% by mass, further 5˜30% by mass.

  When using an epoxy-type compound for the monomer used together, it is preferable to make it into the range of 0-50 mass%, 1-30 mass%, 5-15 mass% with respect to the N-substituted amide monomer having a hydroxy group. .

  The active energy ray-curable adhesive contains a curable component, but in addition to the above components, an additive may be appropriately added if necessary. The active energy ray-curable adhesive can be used in an electron beam curable type or an ultraviolet curable type. When the adhesive is used as an electron beam curable type, it is not particularly necessary for the adhesive to contain a photopolymerization initiator, but when used as an ultraviolet curable type, a photopolymerization initiator is used. . The usage-amount of a photoinitiator is about 0.1-10 mass parts normally per 100 mass parts of sclerosing | hardenable components, Preferably, it is the range of 0.5-3 mass parts.

  Examples of additives include sensitizers that increase the curing speed and curing sensitivity represented by electron beams such as carbonyl compounds, adhesion promoters such as silane coupling agents and ethylene oxide, and improved wettability with optical films. Additives, acryloxy group compounds and hydrocarbons (natural and synthetic resins), additives that improve mechanical strength and processability, UV absorbers, anti-aging agents, dyes, processing aids, ions Examples include trapping agents, antioxidants, tackifiers, fillers (other than metal compound fillers), plasticizers, leveling agents, foaming inhibitors, and antistatic percents. Moreover, you may contain oxetanes, polyols, etc.

  The application method and the curing method of the active energy ray-curable adhesive will be described later.

<Polarizer>
The polarizer, which is the main component of the polarizing plate, is an element that passes only light having a plane of polarization in a certain direction, and a typical known polarizer is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  As the polarizer, a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used. The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and particularly preferably in the range of 5 to 15 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol. % Ethylene-modified polyvinyl alcohol is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73 ° C. is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.

<Protective film>
In the polarizing plate of the present invention, as shown in FIG. 2, a protective film is further provided on the polarizer surface opposite to the surface on which the optical film of the present invention is disposed via an active energy ray-curable adhesive. It is preferable that they are laminated.

  The protective film can be obtained as a commercial product. For example, Konica Minoltak KC4UE, KC8UE, KC8UX, KC5UX, KC8UY, KC4UY, KC4CZ, KC6UA, KC4UA, and KC2UA (manufactured by Konica Minolta Advanced Layer Co., Ltd.) ) And the like.

  In particular, the protective film disposed on the viewing side is preferably provided with functional layers such as a hard coat layer, an antistatic layer, an antireflection layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer.

<Production method of polarizing plate>
A polarizing plate can be manufactured by bonding the optical film of the present invention to one surface of a polarizer using an active energy ray-curable adhesive. In the case where the adhesiveness is different between both surfaces of the optical film, it is preferable that the optical film is bonded to the one having better adhesiveness.

  Hereinafter, an example of the manufacturing method of the polarizing plate using an active energy ray hardening adhesive is demonstrated.

  The polarizing plate includes an adhesive application step of applying an active energy ray-curable adhesive below to form an adhesive layer on at least one of the adhesive surfaces of the polarizer and the optical film, and the adhesive layer. A manufacturing process including a bonding step in which a polarizer and an optical film are bonded to each other via an adhesive layer, and a curing step in which the adhesive layer is cured in a state where the polarizer and the optical film are bonded to each other through the adhesive layer. It can be manufactured by a method. In addition, there may be a pretreatment process for easily bonding the surface of the optical film to which the polarizer is bonded.

(Pretreatment process)
In the pretreatment step, the surface of the optical film that adheres to the polarizer is subjected to an easy adhesion treatment. When the optical film and the protective film are bonded to both surfaces of the polarizer, easy adhesion treatment is performed on each of the optical film and the protective film. In the next adhesive application process, the surface subjected to the easy adhesion treatment is treated as a bonding surface with the polarizer, and therefore, on both surfaces of the optical film, the surface to be bonded with the active energy ray-curable adhesive is easily Apply adhesive treatment. As easy adhesion treatment. Examples include corona treatment and plasma treatment.

(Adhesive application process)
In the adhesive application step, the active energy ray-curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the optical film. When the active energy ray-curable adhesive is applied directly to the surface of the polarizer or the optical film, the application method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting an active energy ray hardening adhesive between a polarizer and an optical film, the method of pressing with a roller etc. and spreading uniformly can also be utilized.

(Bonding process)
After apply | coating an active energy ray hardening adhesive agent by said method, it processes by a bonding process. In this bonding step, for example, when an active energy ray-curable adhesive is applied to the surface of the polarizer in the previous application step, an optical film is superimposed thereon. When the active energy ray-curable adhesive is applied to the surface of the optical film in the previous application step, a polarizer is superimposed thereon. Moreover, when an active energy ray-curable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superposed in that state. When an optical film and a protective film are bonded to both sides of a polarizer, and both sides use an active energy ray-curable adhesive, both sides of the polarizer are optically bonded via an active energy ray-curable adhesive. A film and a protective film are overlaid. Usually, in this state, both sides (when the optical film is superimposed on one side of the polarizer, the polarizer side and the optical film side, and when the optical film and the protective film are superimposed on both sides of the polarizer, The pressure is sandwiched between rollers and the like from both sides of the optical film and the protective film side. As the material of the roller, metal, rubber or the like can be used. The rollers arranged on both sides may be made of the same material or different materials.

(Curing process)
In the curing step, an active energy ray curable adhesive is irradiated with active energy rays, and a cationic polymerizable compound (eg, epoxy compound or oxetane compound) or a radical polymerizable compound (eg, acrylate compound, acrylamide type). The active energy ray-curable adhesive containing the compound or the like is cured, and the polarizer and the optical film, or the polarizer and the retardation film, which are superposed via the active energy ray-curable adhesive, are bonded. When bonding an optical film to the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or an optical film side. Moreover, when bonding an optical film and a protective film on both surfaces of a polarizer, in a state where the optical film and the protective film are superposed on both surfaces of the polarizer via an active energy ray-curable adhesive, It is advantageous to irradiate and simultaneously cure the active energy ray curable adhesive on both sides.

  Visible light, ultraviolet rays, X-rays, electron beams, etc. can be used as the active energy rays applied for curing, but electron beams and ultraviolet rays are generally preferred because they are easy to handle and have a sufficient curing rate. Used.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. When the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. When the acceleration voltage exceeds 300 kV, the penetrating force through the sample is too strong and the electron beam rebounds, and an optical film or polarized light. There is a risk of damaging the child. The irradiation dose is in the range of 5 to 100 kGy, more preferably in the range of 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, the optical film and the polarizer are damaged, resulting in a decrease in mechanical strength and yellowing, thereby obtaining predetermined optical characteristics. Can not.

Arbitrary appropriate conditions can be employ | adopted for the irradiation conditions of an ultraviolet-ray, if it is the conditions which can harden the said adhesive agent. The dose of ultraviolet rays is preferably in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

  When the production method is performed in a continuous line, the line speed depends on the curing time of the adhesive, but is preferably in the range of 1 to 500 m / min, more preferably 5 to 300 m / min, and still more preferably 10 to 100 m. / Min. When the line speed is too slow, productivity is poor, or damage to the optical film is too great, and a polarizing plate that can withstand a durability test cannot be produced. When the line speed is too high, the adhesive is not sufficiently cured, and the target adhesiveness may not be obtained.

  In the polarizing plate obtained as described above, the thickness of the adhesive layer is not particularly limited, but is usually within a range of 0.01 to 10, and preferably within a range of 0.5 to 5 μm.

<Liquid crystal display device>
The polarizing plate of the present invention can be suitably used for a liquid crystal display device. Since the liquid crystal display device using the polarizing plate of the present invention uses an optical film having a low moisture permeability, color unevenness of the liquid crystal display device due to water content hardly occurs.

  The glass used for the panel of the liquid crystal display device preferably has a thickness in the range of 0.3 to 0.7 mm, and more preferably in the range of 0.3 to 0.5 mm. Since the polarizing plate of the present invention is not easily deformed, it is preferably used particularly when the glass thickness is small.

  Bonding between the surface of the polarizing plate on the side of the optical film of the present invention and at least one surface of the liquid crystal cell can be performed by a known method. Depending on the case, it may be bonded through an adhesive layer.

  The mode (driving method) of the liquid crystal display device is not particularly limited, and liquid crystal display devices in various drive modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, and OCB can be used.

  In particular, since the optical film of the present invention satisfies the conditions 1 and 2 as retardation values, VA (MVA, PVA) is used as an optical compensation film (also referred to as a retardation film) that expands the viewing angle. It is suitably provided in a liquid crystal display device of a type (vertical alignment type).

  By providing a polarizing plate including the optical film of the present invention in these liquid crystal display devices, even a liquid crystal display device having a large screen of 30 type or more has excellent visibility with no unevenness of the liquid crystal display device. A liquid crystal display device can be obtained.

  EXAMPLES 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.

<Preparation of optical film 1>
(Preparation of dope 1)
Cellulose ester (diacetyl cellulose: acetyl group substitution degree 2.3 (described as Ac in the table), weight average molecular weight (Mw) 185,000) 100 parts by mass Compound 1 (retardation increasing agent: represented by general formula (1) Compound A-022)
4 parts by mass Matting agent: R972V (manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size = 16 nm)
0.30 parts by mass Methylene chloride 300 parts by mass Ethanol 40 parts by mass The above compositions were sufficiently dissolved with stirring and heating to prepare Dope 1.

(Formation of optical film 1)
The prepared dope 1 was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m.

  Next, the solvent of the peeled dope 1 is evaporated at 35 ° C., slit to 1 m width, then 1.1 times in the transport direction (MD direction) by zone stretching, and the width direction (TD direction) by tenter stretching. The film was dried at a drying temperature of 135 ° C. while being stretched 1.5 times. At this time, the residual solvent amount when starting stretching with the tenter was 8%.

  After stretching with a tenter, relaxation treatment was performed at 130 ° C. for 5 minutes, and then drying was completed while transporting a drying zone at 120 ° C. and 140 ° C. with a large number of rollers. Was subjected to a knurling process having a width of 10 mm and a height of 5 μm, and then wound around a core to produce an optical film 1 according to the present invention. The film thickness was 30 μm and the winding length was 4000 m.

[Preparation of optical films 2 to 37]
In the production of the optical film 1, the type of cellulose ester used for the preparation of the dope, the type and amount of the compound represented by the general formula (1) (compound 1), other than the compound represented by the general formula (1) Optical films 2 to 37 were produced in the same manner except that the types and addition amounts of the compounds having a molecular weight of 10,000 or less (compound 2 and compound 3) and the film thickness were changed as shown in Tables 2 and 3.

  In Table 2 and Table 3, as for the substituent of the cellulose ester, the acetyl group is described as Ac, and the propionyl group is described as Pr. In any case, the total substitution degree represents the total acyl group substitution degree of the cellulose ester.

(Weight average molecular weight measurement)
The weight average molecular weight of the cellulose ester was measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  Moreover, the detail of the compound described by the abbreviation in Table 2 and Table 3 is as follows.

<Compound 1>
Compound 1 is a compound having a function of increasing the retardation value. In addition to the exemplified compound A-022, compounds represented by B1 to B4 shown below and comparative compounds C-1 to C-3 are used. It was.

<Compound 2 and Compound 3: Sugar ester compound: In Table 2 and Table 3, expressed as sugar ester>
Compound 2 and Compound 3 are compounds having a molecular weight of 10,000 or less according to the present invention.

  As the sugar ester compound used in the examples, a compound having an average substitution degree adjusted as follows using FA-3, which is an exemplary compound represented by the general formula (FA), was used.

Sugar ester 1: Average substitution degree 5.5
Sugar ester 2: Average substitution degree 4.5
Sugar ester 3: Average substitution degree 5.0
Sugar ester 4: Average substitution degree 6.5
Sugar ester 5: Average substitution degree 7.0
<Compounds 2 and 3: Polyester compound: In Table 2 and Table 3, expressed as polyester 1>
As the polyester compound used in the examples, FB-14, which is an exemplary compound of the compound represented by the general formula (FB), was used. Prepared according to the following synthesis method.

<Synthesis of ester compounds>
251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, stirrer, and slow cooling tube The flask was charged and gradually heated with stirring until it reached 230 ° C. in a nitrogen stream. The ester compound was obtained by making it dehydrate-condense for 15 hours, and distilling unreacted 1, 2- propylene glycol under reduced pressure at 200 degreeC after completion | finish of reaction. The acid value was 0.10 mg / g and the molecular weight was 491.

<Compound 2: Acrylic compound: In Table 2, expressed as acrylic 1 and acrylic 2>
[Synthesis of Acrylic Copolymer 1]
In a SUS polymerization reactor having an internal volume of 40 liters equipped with a stirrer, 24 liters of deionized water was added, and 36 g of sodium sulfate was added as a dispersion stabilizing aid and stirred and dissolved. In a container equipped with another stirrer, a monomer mixture of 9600 g of methyl methacrylate and 2400 g of 2-hydroxyethyl methacrylate, 12 g of 2,2′-azobisisobutyronitrile as a polymerization initiator, and a chain transfer agent 24 g of n-octyl mercaptan and 24 g of stearyl alcohol as a release agent were added and stirred and dissolved. The monomer mixture in which the polymerization initiator, the chain transfer agent and the release agent thus obtained were dissolved was converted into a 40-liter SUS polymerization reaction apparatus (deionized water, dispersion-stabilized) equipped with the stirrer described above. Containing the agent and the dispersion stabilizing aid) and stirred at 175 rpm for 15 minutes while purging with nitrogen. Thereafter, the polymerization was started by heating to 80 ° C., and after completion of the polymerization exothermic peak, a heat treatment was performed at 115 ° C. for 10 minutes to complete the polymerization. The obtained bead polymer was filtered, washed with water, and dried at 80 ° C. for 24 hours to obtain an acrylic copolymer 1 of methyl methacrylate and 2-hydroxyethyl methacrylate. The weight average molecular weight measured using GPC was 8,000.

[Synthesis of Acrylic Copolymer 2]
In the synthesis | combination of the acryl-type compound 1, the same synthesis | combination was performed except having replaced 2-hydroxyethyl methacrylate with methyl acrylate, and the acrylic copolymer 2 of methyl methacrylate and methyl acrylate was obtained. The weight average molecular weight measured using GPC was 12000.

<Other compounds in Table 2 and Table 3>
PETB: Pentaerythritol tetrabenzoate, molecular weight 550
Hydrogen bonding compound: 3-methylsalicylic acid, molecular weight 150
TPP: triphenyl phosphate, molecular weight 326
BDP: biphenyl diphenyl phosphate, molecular weight 402
<< Evaluation of optical film >>
About each produced said optical film, the following characteristic value was measured and evaluated.

[Measurement of retardation value]
About the produced optical film, retardation values Ro and Rt represented by the following formulas using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments) at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55%. Was measured.

  Specifically, after the optical film was subjected to three-dimensional refractive index measurement at 10 locations at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and the average values of the refractive indexes nx, ny and nz were obtained, In-plane direction retardation value Ro and thickness direction retardation value Rt were calculated according to the following formula.

Formula (i): Ro (590) = (n x -n y) × d
Formula (ii): Rt (590) = {(n _x + n _y ) / 2−n _z } × d
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
[Measurement of retardation value due to humidity fluctuation]
After the optical film was conditioned at 23 ° C. and 20% RH for 5 hours, the Rt value measured in the same environment was measured and set to Rt _20% (590), and the same film was continuously maintained at 23 ° C. and 80% RH. After adjusting the humidity for 5 hours, the Rt value measured in the same environment was determined and this was set to Rt _80% (590), and the change amount ΔRt (590) was determined from the following equation.

ΔRt (590) = | Rt _20% (590) −Rt _80% (590) |
Furthermore, the humidity-controlled sample was measured again in an environment of 23 ° C. and 55% RH, and it was confirmed that this change was a reversible change. A smaller value indicates that the value is more stable against humidity fluctuations.

[Bleed-out resistance]
The produced optical film was allowed to stand in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH for 100 hours, and then bleed-out resistance was evaluated.

  The presence or absence of bleed out was evaluated by observing the surface of the film.

○: No bleed out on the film surface △: Partial bleed out can be seen on the film surface ×: Full bleed out can be clearly seen on the film surface [Slitting]
After attaching the 60 ° worn upper blade and the 90 ° lower blade to the hydraulic table press machine at a distance of 30 μm, each optical film was placed between both blades, and the lowering speed of the upper blade was 6 m / In minutes, 100 samples having a width of 90 cm and a length of 100 cm were continuously cut out. The cut surfaces of the cut samples were observed at 50 times using an optical microscope, and the sharpness was compared. The number of films in which some defects such as burrs, cleavage, cutting, or chipping occurred was counted, the defect rate was calculated, and the cutting property was evaluated according to the following criteria.

○: The defect rate is less than 2% Δ: The defect rate is less than 2 to 5% ×: The defect rate is 5% or more Here, it was determined that ○ and Δ were practically acceptable levels.

  The contents of the optical film and the results of the evaluation are summarized in Table 2 and Table 3 below.

<Production of polarizing plate>
[Preparation of Polarizing Plate 1]
(Production of polarizer)
A 30 μm thick polyvinyl alcohol film was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution at 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. . The obtained film was uniaxially stretched under conditions of a stretching temperature of 55 ° C. and a stretching ratio of 5 times. This uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 10 μm.

(Preparation of active energy ray-curable adhesive solution: cationic polymerization type, described as UV in the table)
Each of the following components was mixed and then defoamed to prepare an active energy ray-curable adhesive solution. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Industries) 40 parts by mass 1,4-butanediol diglycidyl ether 15 parts by mass Triarylsulfonium hexafluorophosphate 2.3 parts by mass 9,10-dibutoxyanthracene 0.1 parts by mass 1,4-diethoxynaphthalene 2.0 parts by mass (Preparation of polarizing plate 1)
A polarizing plate 1 having the configuration of the polarizing plate 101A of FIG. The numerical value in parentheses indicates the number of each component described in FIG.

  First, as a protective film (102), a KC6UA film (manufactured by Konica Minolta Advanced Layer Co., Ltd.) was prepared, and the prepared active energy ray-curable adhesive liquid was microgravure coater (gravure roller: # 300, rotational speed). 140% / line speed) was applied to a thickness of 5 μm to form an active energy ray-curable adhesive (103A).

  Next, the active energy ray-curable adhesive liquid prepared above was applied to the optical film 1 (105) thus prepared so as to have a thickness of 5 μm, as described above, and the active energy ray-curable adhesive ( 103B) was formed.

  Between the active energy ray-curable adhesives (103A) and (103B), the produced polyvinyl alcohol-iodine polarizer (104) is placed and bonded with a roller machine, and the protective film 1 (102). A laminate in which / active energy ray-curable adhesive (103A) / polarizer (104) / active energy ray-curable adhesive (103B) / optical film 1 (105) was laminated was obtained. In that case, it bonded by the roller machine so that the slow axis of an optical film (105) and the absorption axis of a polarizer (104) might become mutually orthogonal.

  The polarizing plate 1 (101A) was produced by irradiating an electron beam from both sides of the laminate.

  The line speed was 20 m / min, the acceleration voltage was 250 kV, and the irradiation dose was 20 kGy.

[Preparation of polarizing plates 2 to 37]
In the production of the polarizing plate 1, the optical film 1 is changed to the optical films 2 to 37, and PVA water paste (described as PVA in the table) is used in combination as the adhesive described in Tables 2 and 3, respectively. Thus, polarizing plates 2 to 37 were produced.

<Production of liquid crystal display device>
Using the commercially available VA type liquid crystal display device (40 type display KLV-40J3000 made by SONY), the polarizing plates bonded to both surfaces of the liquid crystal cell are peeled off, and the produced polarizing plates 1 to 37 are shown in FIG. In this way, liquid crystal display devices 1 to 37 were prepared by bonding to both surfaces of the liquid crystal cell. At that time, the direction of the absorption axis of the polarizing plate was adjusted to the same direction as the polarizing plate bonded in advance.

<< Evaluation of Polarizing Plate and Liquid Crystal Display >>
Each evaluation below was performed about each produced said liquid crystal display device and each polarizing plate used for the production.

(Evaluation of moisture resistance: Evaluation of color unevenness due to fluctuations in water content)
Bencot (manufactured by Asahi Kasei Fibers Co., Ltd.) soaked in water was placed on the surface of the liquid crystal display device produced above and held for 30 hours in a state where moisture did not evaporate. Next, each liquid crystal display device was turned on, the uniformity of the display screen was visually evaluated, and the moisture resistance was evaluated according to the following criteria.

◎: No color unevenness is observed at all ○: Slightly weak color unevenness is observed, but the quality has no problem in practical use △: Color unevenness is observed ×: Strong color unevenness occurs The contents of the optical film, which is a quality that has a problem with moisture resistance, and the results of the evaluation are summarized in Table 2, Table 3, and Table 4 below.

  The optical films 1 to 33 of the present invention satisfy the retardation value and the variation range of the retardation value from Condition 1 to Condition 3 according to the present invention with respect to Comparative Examples 35 to 37, and a sufficiently high retardation value. The stability of the retardation value in the thickness direction due to fluctuations in humidity. In addition, it has excellent bleed-out resistance and slitting properties. Furthermore, it is clear that a polarizing plate and a liquid crystal display device using the optical film are excellent in color unevenness due to variation in water content. Further, in addition to the compound represented by the general formula (1), when compared with a level in which a compound having a molecular weight of 10,000 or less is added (for example, comparison between optical films 1 and 2 and 10 and 11), It can be seen that by adding a compound having a molecular weight of 10,000 or less, color unevenness due to fluctuations in water content of the display device is further improved.

  The optical film 34 using the 1,3,5-triazine compound (C-1) other than the compound represented by the general formula (1) according to the present invention as a retardation increasing agent has a bleedout resistance, and The color unevenness due to the water content variation of the display device was slightly inferior.

  The optical film 26 using diacetyl cellulose having a degree of acetyl group substitution lower than the preferred range of the present invention was somewhat deteriorated in slitting characteristics due to poor film brittleness.

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15 Filter 4, 13 Stock tank 5, 14 Liquid feed pump 8, 16 Conduit 10 Ultraviolet absorber charging pot 20 Merge pipe 21 Mixer 30 Die 31 Metal support 32 Web 33 Peeling position 34 Tenter device 35 Roller dryer 41 Feeding tank 42 Stock tank 43 Pump 44 Filter 101A, 101B Polarizing plate 102 Protective film 103A, 103B Active energy ray curable adhesive 104 Polarizer 105 Optical film of the present invention 106 Functional layer 107 Liquid crystal cell 108 Liquid crystal display device

Claims (6)

An optical film containing a compound having a function of raising the at least cellulose ester and retardation value, the optical film, meets all the conditions from the following conditions 1 to condition 3, and,
The optical film, wherein the compound having a function of increasing the retardation value is a compound represented by the following general formula (1) .
Condition 1: An in-plane retardation value Ro (590) represented by the following formula (i) measured at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55% is in the range of 30 to 150 nm.
Formula (i): Ro (590) = (n x -n y) × d
Condition 2: Retardation value Rt (590) in the thickness direction represented by the following formula (ii) measured at a wavelength of 590 nm under an environment of a temperature of 23 ° C. and a relative humidity of 55% is within a range of 70 to 300 nm. is there.
Formula (ii): Rt (590) = {(n _x + n _y ) / 2−n _z } × d
Condition 3: The amount of change in retardation value Rt (590) in the thickness direction (ΔRt (590)) when the relative humidity is changed to a range of 20 to 80% in an environment of a temperature of 23 ° C. is 0 to It is in the range of 10 nm.
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x which refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]

(In General Formula (1), R ₁₃ and R ₂₃ each represent a substituent. K3 represents an integer of 1 to 5. m3 represents an integer of 0 to 4.) Claim 1 in addition to the compound represented by the general formula (1), the molecular weight of the compound is 10,000 or less, characterized in that it contains in the range of 6 to 40 parts by mass with respect to 100 parts by weight of cellulose ester the optical film according to. The optical film according to claim 2 , wherein the compound having a molecular weight of 10,000 or less is at least one selected from a sugar ester compound, a polyester compound, and an acrylic compound. The optical film according to any one of claims 1 to 3 , wherein the cellulose ester satisfies both the following formulas (a) and (b).
Formula (a) 2.0 ≦ X + Y ≦ 2.6
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group. Y represents the degree of substitution of the propionyl group or butyryl group or the total degree of substitution thereof.) A polarizing plate, wherein the optical film according to any one of claims 1 to 4 is bonded to a polarizer with an active energy ray-curable adhesive. 6. A liquid crystal display device, wherein the polarizing plate according to claim 5 is provided in at least one of the liquid crystal cells.

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