JP5888333B2 - Polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to a polarizing plate and a liquid crystal display device using cellulose acylate.

  Among cellulose esters, it is known that cellulose acylate can be applied to optical films having a wide range of retardation by changing the acyl group substitution degree. Generally, triacetyl cellulose (TAC) having a high degree of acetyl group substitution is suitably used for a protective film for polarizing plates because of its low retardation. On the other hand, in order to use triacetyl cellulose as an optical compensation film in various liquid crystal modes such as VA type and TN type, since the expression of retardation is insufficient, it is necessary to add a retardation increasing agent (for example, patents) Reference 1).

  On the other hand, diacetyl cellulose (DAC) having a low degree of acetyl group substitution has high retardation expression, and therefore can function as an optical compensation film without adding a retardation increasing agent. Expected.

  When a film made of cellulose acylate having a small acyl group substitution degree is used as an optical compensation film, it is generally bonded to a polarizer to produce a polarizing plate. And when durability as a polarizing plate is considered, the adhesiveness between a cellulose acylate film and a polarizer is so preferable that it is high.

  Moreover, when bonding a cellulose acylate film and a polarizer, the process of superimposing the slow axis of a cellulose acylate film and the absorption axis of a polarizer exactly in parallel or at right angles is required. This is because the polarization degree of the polarizing plate decreases when these two axes are slightly shifted and a phenomenon called axial shift occurs. The higher the retardation development performance of the cellulose acylate film, the more pronounced the decrease in the degree of polarization. Therefore, it is desired to develop a means that can alleviate the decrease in the degree of polarization caused by the axis deviation.

  Until now, polyvinyl alcohol-based adhesives have been widely used for adhesion between a polarizer and a polarizing plate protective film made of cellulose acylate. At that time, it was necessary to hydrophilize the surface of the cellulose acylate film in advance with an alkali saponification solution or the like. However, the cellulose acylate film having a low degree of acyl group substitution has a problem that in the alkali saponification step, a part of the film is eluted into the alkali saponification solution and contaminates the step. Therefore, an adhesive that does not require an alkali saponification step has been desired.

  In recent years, a photocurable adhesive has attracted attention as an adhesive for bonding a polarizer and a polarizing plate protective film (for example, see Patent Documents 2 to 4). Since the photocurable adhesive can be bonded to the polarizer without passing through the alkali saponification step, it can be expected to be applied to cellulose acylate having a low degree of acyl group substitution.

  However, when the present inventors bonded the optical compensation film made of cellulose acylate having a small acyl group substitution degree and the polarizer using a photocurable adhesive, the adhesion with the polarizer is not sufficient, Moreover, the problem that the polarization degree of a polarizing plate falls significantly was discovered. This is presumed to be caused by a slight misalignment of the orientation angle of the optical compensation film due to heat generation or curing shrinkage during curing of the photocurable adhesive, resulting in an axial misalignment.

European Patent No. 91656 JP 2010-39298 A JP 2009-244860 A JP 2009-211057 A

  This invention is made | formed in view of the said problem and the situation, and the solution subject is the adhesiveness of the cellulose acylate film which comprises a polarizing plate, and a polarizer, when using a photocurable adhesive agent. An object of the present invention is to provide a polarizing plate that improves and further reduces the decrease in the degree of polarization. Moreover, it is providing the liquid crystal display device provided with the said polarizing plate.

  In order to solve the above-mentioned problems, the present inventor adopts a cellulose acylate film containing a cellulose acylate having a low acyl group substitution degree and a glass transition temperature lowering agent in the course of examining the cause of the above-mentioned problem. It has been found that a high retardation value and high phase difference expression are exhibited while being a thin film. In addition, when the present inventors use a photocurable adhesive to bond a polarizer and a cellulose acylate film, the distribution of the glass transition temperature lowering agent on the bonding surface is made larger than that on the other surface, thereby bonding. It has been found that the adhesion of the mating surface is improved and a decrease in the degree of polarization is suppressed, and the present invention has been achieved.

That is, the said subject which concerns on this invention is solved by the following means.
1. A cellulose acylate film containing a cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5 and a glass transition temperature lowering agent is formed on one of the polarizers using a photocurable adhesive. A polarizing plate bonded to a surface,
The detected value of the glass transition temperature reducing agent on the bonding surface of the cellulose acylate film, detected using time-of-flight secondary ion mass spectrometry (TOF-SIMS), is d _A , and the detected value of the other surface The polarizing plate is characterized in that the r value represented by the following formula (1) is 1.1 or more, where d is _B.
Formula (1) r = d _A / d _B
2. 2. The polarizing plate according to item 1, wherein the cellulose acylate is diacetyl cellulose having an acyl group substitution degree in the range of 2.0 to 2.5.
3. The glass transition temperature lowering ability of the glass transition temperature lowering agent is 3.5 ° C./part by mass or more.
4). The cellulose acylate film further comprises a hydrolysis inhibitor,
4. The polarizing plate according to claim 1, wherein an average log P value of the hydrolysis inhibitor is 7.5 or more.
5. The arithmetic average roughness of the said bonding surface is larger than the other surface, The polarizing plate as described in any one of said 1st term | claim-4th term | claim characterized by the above-mentioned.
6). The polarization degree of the polarizing plate is 99.99% or more, The polarizing plate according to any one of the first to fifth items.
7). A liquid crystal display device comprising the polarizing plate according to any one of the first to sixth items.

By the above means of the present invention, the adhesion between the cellulose acylate film and the polarizer can be improved, and the decrease in the degree of polarization of the polarizing plate can be alleviated.
The expression mechanism or action mechanism of the effect of the present invention has not been clarified, but is presumed as follows.
That is, when a cellulose acylate film is bonded to a polarizer using a photocurable adhesive, the bonding surface is smaller than the other surface due to the presence of a glass transition temperature reducing agent in the bonding surface. Has a rough surface structure. This surface structure is considered to contribute to the improvement of the adhesion with the polarizer.
Moreover, the abundance of cellulose acylate decreases with an increase in the abundance of the glass transition temperature lowering agent on the bonding surface. Therefore, it is considered that the retardation value of the cellulose acylate film in the vicinity of the bonding surface is smaller than the value of the whole cellulose acylate film. As the retardation value of the cellulose acylate film is higher, the decrease in the degree of polarization due to misalignment at the time of bonding is more conspicuous, and by bonding the bonding surface and the polarizer with a relatively small retardation, It is thought that the decrease in the degree of polarization is alleviated.

The polarizing plate of the present invention comprises a cellulose acylate film containing a cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5 and a glass transition temperature reducing agent, a photocurable adhesive. The polarizing plate bonded to one surface of the polarizer using the time-of-flight secondary ion mass spectrometry (TOF-SIMS), which is detected using the bonding surface of the cellulose acylate film when the detected value of the glass transition temperature lowering agent and d _a, the detection value of the other surface and d _B, and wherein the r value represented by the formula (1) is 1.1 or more. This feature is a technical feature common to the inventions according to claims 1 to 7.

As an embodiment of the present invention, the cellulose acylate is preferably diacetyl cellulose having an acyl group substitution degree in the range of 2.0 to 2.5 from the viewpoint of manifesting the effects of the present invention. Moreover, it is preferable that the glass transition temperature decreasing ability of the said glass transition temperature decreasing agent is 3.5 degreeC / mass part or more. Moreover, it is preferable that the said cellulose acylate film further contains a hydrolysis inhibiting agent and the average logP value of the said hydrolysis inhibiting agent is 7.5 or more. Moreover, it is preferable that the arithmetic mean roughness of the said bonding surface is larger than the other surface. The polarization degree of the polarizing plate is preferably 99.99% or more.
The polarizing plate of the present invention can be 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.

<Polarizing plate>
The polarizing plate according to the present invention is a photocurable adhesive comprising a cellulose acylate film having an acyl group substitution degree in the range of 2.0 to 2.5 and a glass transition temperature reducing agent. It is bonded to one surface of the polarizer using an agent.

<Cellulose acylate film>
The cellulose acylate film used in the present invention contains a cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5. By adopting cellulose acylate having a low acyl group substitution degree in this way, high retardation development is exhibited, and even when a retardation film having a high retardation is obtained, a thin film can be obtained. In addition, even when a high phase difference is developed, the stretch ratio can be kept low, and advantages such as failure such as breakage can be avoided.

  Here, the cellulose molecule consists of many glucose units connected, and the glucose unit has three hydroxy groups (hydroxyl groups). The number of acyl groups derived from these three hydroxy groups is called the degree of acyl group substitution. For example, diacetylcellulose (DAC) has an acetyl group bonded to an average of 2.0 to 2.5 hydroxy groups among the three hydroxy groups of the glucose unit.

  Examples of the cellulose acylate used in the present invention include carboxylic acid esters having about 2 to 22 carbon atoms, which may be esters of aromatic carboxylic acids, but are particularly preferably lower fatty acid esters of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The acyl group bonded to the hydroxy group may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted. The carbon number is preferably selected from acyl groups having 2 to 6 carbon atoms. The acyl group preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  For example, cellulose acetate, cellulose propionate, cellulose butyrate and the like, cellulose acetate propio as described in JP-A Nos. 10-45804, 8-231761, US Pat. No. 2,319,052, etc. It is preferable to use mixed fatty acid esters such as nate, cellulose acetate butyrate, and cellulose acetate phthalate.

The acyl group substitution degree of cellulose acylate can be measured in accordance with ASTM D-817-91, and the preferred acyl group substitution degree is 2.18 to 2.45.
When the acyl group substitution degree of cellulose acylate is 2.0 or more, it is possible to prevent the occurrence of deterioration in film surface quality due to increase in dope viscosity and haze-up due to increase in stretching tension. Further, when the acyl group substitution degree is 2.5 or less, a necessary phase difference is easily obtained.

The number average molecular weight (Mn) of the cellulose acylate is preferably in the range of 30,000 to 300,000 because the mechanical strength of the obtained cellulose acylate film is strong. Further, cellulose acylate having a number average molecular weight of 50,000 to 200,000 is preferably used.
The ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acylate (Mw / Mn) is preferably in the range of 1.4 to 3.0.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) of cellulose acylate are measured using gel permeation chromatography (GPC).
The measurement conditions are as follows.
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 cellulose acylate used in the present invention can be synthesized by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.
Cellulose as a raw material for cellulose acylate is not particularly limited, and examples thereof include cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like. Moreover, you may use the cellulose acylate obtained from them by mixing in arbitrary ratios, respectively.
On the other hand, a commercially available cellulose acylate may be used. Examples of commercially available cellulose acylates include L20, L30, L40, and L50 manufactured by Daicel, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical.

<Glass transition temperature lowering agent>
The cellulose acylate film used in the present invention contains a glass transition temperature lowering agent (hereinafter referred to as Tg lowering agent). Thus, when a cellulose acylate film contains a Tg reducing agent, the glass transition temperature Tg of the cellulose acylate which has a hard and brittle property can fall, and the workability and mechanical physical property can be improved. As a result, the cellulose acylate film has a high retardation value despite being a thin film, suppresses an increase in internal haze even when stretched at a high magnification, reduces retardation unevenness, and suppresses an increase in haze even in a humid heat environment. Can be provided.

The Tg lowering agent used in the present invention means that the glass transition temperature Tg of a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 alone is not added. Any substance may be used as a Tg lowering agent as long as it means an additive that lowers and satisfies such a definition.
In addition, the value of the glass transition temperature Tg of a cellulose acylate film is a value measured by the differential scanning calorimetry (DSC).

  In addition, depending on the type of cellulose acylate having an acyl group substitution degree of 2.0 to 2.5, when a certain substance falls into the case where it falls under the definition of the Tg lowering agent and when it does not fall, the substance is If it is a combined use with a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 when the definition falls under the definition of a Tg reducing agent, it can be used as a Tg reducing agent in the present invention.

〔式中、Ｘはセルロースアシレートを単独で製膜して得られたセルロースアシレートフィルムのガラス転移温度Ｔｇを表し、Ｙは当該セルロースアシレート１００質量部に対し、Ｔｇ低下剤を５質量部添加した後に同様に製膜して得られたセルロースアシレートフィルムのガラス転移温度Ｔｇを表す。〕The glass transition temperature lowering ability (hereinafter referred to as Tg lowering ability) of the Tg lowering agent is not particularly limited, but is preferably 3.5 ° C / part by mass or more, more preferably 3.8 ° C / part by mass. It is above, More preferably, it is 4.0 degrees C / mass part or more.
Here, the Tg lowering ability means the ability to lower the glass transition temperature Tg per unit mass of a certain substance, and is defined by the following mathematical formula (3).

[Wherein, X represents a glass transition temperature Tg of a cellulose acylate film obtained by independently forming a cellulose acylate, and Y represents 5 parts by mass of a Tg reducing agent with respect to 100 parts by mass of the cellulose acylate. The glass transition temperature Tg of the cellulose acylate film obtained by adding a film in the same manner after the addition is shown. ]

  When the Tg reducing ability of the Tg reducing agent is a value within the above range, an excellent Tg reducing effect can be exhibited even with a small addition amount. For this reason, the bleed-out etc. which generate | occur | produce when the additive must be added in large quantities can be prevented. On the other hand, the upper limit of the Tg lowering ability is not particularly limited, but is actually about 5.0 ° C./part by mass or less.

  In addition, regarding the Tg lowering ability, depending on the type of cellulose acylate having an acyl group substitution degree of 2.0 to 2.5, the substance used as the Tg lowering agent is included in the preferable range of the Tg lowering ability described above. Cases and cases that are not included. In such a case, the substance is preferable as described above only when used in combination with a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 when included in the preferable range of the above-described Tg lowering ability. It shall be interpreted as a Tg lowering agent that satisfies the range of Tg lowering ability.

The specific form of the Tg reducing agent used in the present invention is not particularly limited as long as the definition of the Tg reducing agent described above is satisfied, and preferably the preferable range of the Tg reducing ability described above is satisfied. An example of the Tg lowering agent is a polyester compound represented by the following general formula (I).
General formula (I) X-O-B- {O-C (= O) -A-C (= O) -OB} _n- O-X [wherein B is a straight chain having 2 to 6 carbon atoms. A chain or branched alkylene group, or a linear or branched cycloalkylene group is represented. A represents an aromatic ring having 6 to 14 carbon atoms, a linear or branched alkylene group having 2 to 6 carbon atoms, or a linear or branched cycloalkylene group having 2 to 6 carbon atoms. X represents a monocarboxylic acid residue containing a hydrogen atom or an aromatic ring having 6 to 14 carbon atoms. n represents a natural number of 1 or more. ]

The polyester compound represented by the general formula (I) has an aromatic ring (having 6 to 14 carbon atoms), a linear or branched alkylene group, or a linear or branched cycloalkylene group (both having 2 to 6 carbon atoms). An alternating copolymer obtained by alternating copolymerization of a dicarboxylic acid and a linear or branched alkylene diol or cycloalkylene diol having 2 to 6 carbon atoms.
The aromatic dicarboxylic acid and the dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group may be used alone or as a mixture, but from the viewpoint of compatibility with cellulose acylate. It is preferable that at least 10% or more of the aromatic dicarboxylic acid is contained. Moreover, you may seal both ends with the monocarboxylic acid which has an aromatic ring (C6-C14).

  Examples of the dicarboxylic acid having an aromatic ring (6 to 14 carbon atoms), that is, an aromatic dicarboxylic acid having 6 to 16 carbon atoms include, for example, phthalic acid, isophthalic acid, terephthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4- Naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 4,4'- And biphenyl dicarboxylic acid. Among these, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid are preferable.

  Examples of the dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group (having 2 to 6 carbon atoms) include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and 1,2-cyclohexanedicarboxylic acid. Examples thereof include acid and 1,4-cyclohexanedicarboxylic acid. Of these, succinic acid, adipic acid, and 1,4-cyclohexanedicarboxylic acid are preferable.

  Examples of the linear or branched alkylene diol or cycloalkylene diol having 2 to 6 carbon atoms include ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexane Examples include diol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like. Among these, ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol are preferable.

  Among these, A is preferably a benzene ring, naphthalene ring or biphenyl ring which may have a substituent, from the viewpoint of excellent Tg lowering ability. Here, the substituent which the benzene ring, naphthalene ring or biphenyl ring may have is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.

  Examples of the monocarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms) that seals both ends of the polyester compound include benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, p-tert-butylbenzoic acid, and dimethylbenzoic acid. And paramethoxybenzoic acid. Of these, benzoic acid, p-toluic acid and p-tert-butylbenzoic acid are preferred.

  Aromatic polyester compounds are prepared by the conventional methods of polyesterification reaction of dicarboxylic acid and alkylene diol or cycloalkylene diol, hot melt condensation method by transesterification, or interfacial condensation method of acid chlorides of these acids and glycols. It can be easily synthesized by any method. Furthermore, by adding the aromatic monocarboxylic acid described above, a polyester compound in which both ends are sealed can be synthesized.

Examples of aromatic polyester compounds (PES-1) to (PES-14) and (ar-1) to (ar-20) that can be used in the present invention are shown below.

As described above, the aromatic polyester compound represented by the general formula (I) has been described in detail as a specific example of the Tg reducing agent, but other Tg reducing agents may be used as a matter of course.
In the cellulose acylate film according to one embodiment of the present invention, only one Tg reducing agent may be used alone, or two or more Tg reducing agents may be used in combination. Further, the amount of the Tg reducing agent added in the cellulose acylate film according to one embodiment of the present invention is not particularly limited, but is preferably 1 to 5% by mass, more preferably 100% by mass with respect to cellulose acylate. Is 1.5 to 3.5 mass%. If the added amount of the Tg reducing agent is 1% by mass or more, the Tg reducing performance that is the original purpose of the Tg reducing agent can be sufficiently exhibited. On the other hand, if the addition amount of the Tg reducing agent is 5% by mass or less, the retardation development performance of the cellulose acylate film accompanying the increase in the addition amount of the T reducing agent can be prevented.

The cellulose acylate film according to one embodiment of the present invention is based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) on a bonding surface with a polarizer and other surfaces. The detection value of the Tg lowering agent is characterized by a certain degree of bias.
When this is expressed quantitatively, the detected value of the Tg reducing agent on the bonding surface with the polarizer of the cellulose acylate film, detected using time-of-flight secondary ion mass spectrometry, is expressed as d _A , and the other surface. when the detected value was d _B, is r value shown by the following formula (1) is 1.1 or more.
Formula (1) r = d _A / d _B

Here, time-of-flight secondary ion mass spectrometry can measure the chemical information of atoms and molecules on a solid sample with a sensitivity of one molecular layer or less, and the distribution of specific atoms and molecules with a spatial resolution of 100 nm or less. This is an observable mass spectrometry method. Time-of-flight secondary ion mass spectrometry is a type of secondary ion mass spectrometry (SIMS), in which a solid sample is irradiated with a primary ion beam, and ions emitted from the outermost surface of the sample (two Analysis is performed by detecting (secondary ions). Since a time-of-flight mass spectrometer (TOF-MS) is used as the mass spectrometer, it is referred to as TOF-SIMS.
According to time-of-flight secondary ion mass spectrometry, it is possible to measure a sample substantially non-destructively by irradiating the sample with an ion beam in a pulsed manner. It has been widely applied to the analysis of

  The r value may be 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more, and still more preferably 1.4 or more. On the other hand, since it becomes easy to suppress generation | occurrence | production of a curl at the time of polarizing plate manufacture, it is usually preferable that it is 1.5 or less.

  As described above, the definition and preferred form of the r value, which is an essential constituent requirement in the present invention, have been described, but as a preferred embodiment based on another viewpoint of the cellulose acylate film according to the present invention, along the thickness direction of the film. A form in which there is a concentration gradient of the Tg reducing agent can be mentioned. For example, as the simplest example, when the cellulose acylate film according to the present invention is cut so as to be divided into two equal parts by a plane perpendicular to the thickness direction (a plane parallel to the plane direction of the film), An embodiment in which the amount of the Tg reducing agent present in the fragment including the bonding surface with the polarizer is larger than the amount of the Tg reducing agent present in the other fragment (the fragment including the other surface) is preferably exemplified. The When this is generalized, when the cellulose acylate film according to the present invention is cut so as to be divided into k equal parts by a plane perpendicular to the thickness direction (a plane parallel to the plane direction of the film), each piece An embodiment in which the amount of the Tg reducing agent present in is gradually decreased from the fragment containing the bonding surface with the polarizer toward the fragment containing the other surface is also preferably exemplified. In this embodiment, the case where k = 2 is described separately above, but k is preferably 3 or more, more preferably 5 or more, further preferably 10 or more, and particularly preferably 20 or more. is there.

  According to the cellulose acylate film according to one embodiment of the present invention, the adhesiveness with the polarizer constituting the polarizing plate is further improved by being configured so that the r value is 1.1 or more. Is possible. When cellulose acylate such as DAC having a low acyl group substitution degree is used not only as a retardation film but also as an optical compensation film for expanding a viewing angle, it is bonded to a polarizer to constitute a polarizing plate. It is common. And when durability as a polarizing plate is considered, the adhesiveness between a cellulose acylate film and a polarizer is so preferable that it is high.

The mechanism for improving the adhesion is not completely clear, but according to the study of the present inventor, the following mechanism is presumed.
As will be described later, the cellulose acylate film is usually produced through a step of drying a film obtained by casting a dope containing cellulose acylate and an additive on a support, peeling it, and then stretching it. When adopting a production method in which the r value of the obtained cellulose acylate film is 1.1 or more, one surface of the obtained cellulose acylate film has minute unevenness as compared with the other surface. Many were found to exhibit a rough surface structure.
This is because the cellulose acylate moves flexibly during stretching because the Tg lowering agent having the ability to lower the glass transition temperature Tg of the cellulose acylate is present on one surface in a rich manner. This is thought to be the result of the fact that And it is thought that the rough surface structure which has many such micro unevenness | corrugation contributes to the improvement of adhesiveness with a polarizer.

In addition, the bonding surface of the cellulose acylate film is usually subjected to alkali saponification treatment for the purpose of improving the adhesion at the time of bonding between the polarizer and the cellulose acylate film. However, according to the cellulose acylate film provided by the present invention, the adhesion between the polarizer and the polarizer is improved by the mechanism as described above, so that it is expected that such alkali saponification treatment is unnecessary. In addition, a cost reduction effect can be achieved by reducing the number of man-hours.
Moreover, when alkali saponification treatment is performed, part of cellulose acylate present on the saponification treatment surface (bonding surface) of the cellulose acylate film may be hydrolyzed, but the adhesion is improved. If the alkali saponification treatment becomes unnecessary, the possibility of hydrolysis of the cellulose acylate during the alkali saponification treatment is eliminated, and a very superior technique is provided.

  A preferred embodiment of the cellulose acylate film according to one aspect of the present invention is a quantitative representation of the presence of a surface structure composed of minute irregularities that contributes to improvement in adhesion to a polarizer by the above-described mechanism. is there. That is, in the cellulose acylate film according to one embodiment of the present invention, the arithmetic average roughness Ra measured by JIS B0601: 2001 on the bonding surface with the polarizer, out of the two surfaces of the film, It is preferably larger than the value on the other surface. At this time, the value of the arithmetic average roughness Ra on the bonding surface is preferably 1.05 times or more, more preferably 1.1 times or more, more preferably the value of the arithmetic average roughness Ra on the other surface. Is 1.2 times or more, particularly preferably 1.3 times or more, and most preferably 1.4 times or more.

  Conventionally, when a polarizing plate is produced by laminating a cellulose acylate film and a polarizer, the slow axis of the cellulose acylate film as a retardation film and the absorption axis of the polarizer are precisely overlapped. A process was needed. When pasting, even if these two axes are shifted slightly, so-called axial shift occurs, there is a problem that the polarization degree of the polarizing plate is lowered. The higher the retardation development performance of the cellulose acylate film that constitutes the polarizing plate, the more the reduction in the polarization degree appears. Therefore, the reduction in the polarization degree due to the axis deviation as described above is alleviated. The development of possible means was also highly desired.

  The cellulose acylate film according to one embodiment of the present invention provides a certain solution to such a demand. That is, according to the cellulose acylate film according to one embodiment of the present invention, even if a slight axis shift occurs during bonding with a polarizer, a decrease in the degree of polarization of the polarizing plate due to the misalignment can be alleviated. Although the mechanism is not completely clear, the following mechanism has been estimated according to the study of the present inventor.

  The Tg lowering agent contained in the cellulose acylate film according to one aspect of the present invention reduces the relative abundance of cellulose acylate contributing to the development of retardation as the abundance in the film increases. become. In the cellulose acylate film of the present invention, since there are more Tg reducing agents on the bonding surface with the polarizer than on the other surface, if it is observed microscopically in the vicinity of the bonding surface, It is considered that the retardation values Ro and Rth of the cellulose acylate film are smaller than the macroscopic values of the entire cellulose acylate film. On the contrary, if the other surface vicinity is observed microscopically, it can be considered that the retardation values Ro and Rth are larger than the macroscopic values of the entire cellulose acylate film.

  Even in such a case, if the amount of the Tg reducing agent contained in the whole film and the thickness of the cellulose acylate film are constant, the retardation development performance as a whole film, that is, the retardation values Ro and Rth are Is unchanged. As described above, the higher the retardation development performance of the cellulose acylate film as the retardation film, that is, the retardation values Ro and Rth, the greater the decrease in the degree of polarization due to the axial misalignment with the polarizer. In addition, on the bonding surface with the polarizer, the axis shift of the cellulose acylate film is likely to occur due to external factors such as shrinkage of the adhesive and heat generation during curing. Therefore, when bonding the bonding surface comprised so that retardation values Ro and Rth become microscopically small with a polarizer, the surface where a Tg reducing agent exists uniformly in the whole film can be used as a polarizer. Even if the same degree of axial deviation occurs as compared with the case of pasting, the degree of decrease in the degree of polarization of the polarizing plate can be small. As a result, the decrease in the degree of polarization of the polarizing plate due to the axis deviation is alleviated.

  Conventionally, various devices have been devised so that the additive used to constitute the cellulose acylate film is normally distributed as uniformly as possible inside the film. In other words, those skilled in the art who consider the addition of various additives to the cellulose acylate film should try to have a distribution in the additive formulation even though they may have a more uniform formulation in mind. Should not. Therefore, the present invention capable of exerting the above-described excellent effects by providing the distribution of the Tg lowering agent intentionally under such technical common sense is extremely different from the prior art. It can be said that it provides a technology with high advantage.

<Other additives>
The cellulose acylate film according to one embodiment of the present invention can contain other additives in addition to the above-described Tg reducing agent. Hereinafter, additives that can be used in the present invention will be described.

(Hydrolysis inhibitor)
The cellulose acylate film according to one embodiment of the present invention can contain a hydrolysis inhibitor. Thus, since a cellulose acylate film contains a hydrolysis inhibiting agent, since hydrolysis of a cellulose acylate is prevented, the water resistance of a cellulose acylate film can improve.

  The hydrolysis inhibitor that can be used in the present invention is that the hydrolysis resistance of cellulose acylate alone, which does not contain it, is 2.0 to 2.5, and is reduced by adding it. Any substance may be used as a hydrolysis inhibitor so long as it satisfies such a definition.

  As an index of hydrolysis resistance of a cellulose acylate film for determining whether or not a certain substance is included in the concept of hydrolysis inhibitor, a mass change rate before and after saponification can be used. Specifically, the film is immersed in a 2.0 M KOH aqueous solution at 50 ° C. for 90 seconds, and the mass change rate of the film before and after that is calculated. According to the mass change rate, it is possible to grasp the ratio of cellulose acylate that has been hydrolyzed in the alkaline solution and dissolved in the saponified solution. | D1 |> | d2 where d1% is the mass change rate of a film formed only with cellulose acylate, and d2% is the mass change rate of 5 mass parts of the additive with respect to 100 mass parts of cellulose acylate. When | is satisfied, it can be determined that the additive is a hydrolysis inhibitor for cellulose acylate.

  In addition, depending on the type of cellulose acylate having an acyl group substitution degree of 2.0 to 2.5, when a certain substance falls within the case where the substance falls under the definition of the hydrolysis inhibitor and when it does not, the substance is If it is a combined use with a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 in the case where it falls under the definition of a hydrolysis inhibitor, it can be used as a hydrolysis inhibitor in the present invention.

  Although there is no restriction | limiting in particular about the hydrolysis inhibiting ability of a hydrolysis inhibiting agent, It can represent with the average logP value which is a parameter | index of the hydrophobicity of a hydrolysis inhibiting agent. It can be said that the higher the average log P value, the better the performance as a hydrolysis inhibitor.

Here, the log P value is also called an octanol-water partition coefficient or log Pow, and is defined as a common logarithm of the value of the ratio of the distribution concentration of a substance to each phase of a two-phase solvent system composed of n-octanol and water. . The average log P value is determined by first considering the specific log P value of each compound constituting the mixture in consideration of the case where the hydrolysis inhibitor is used as a mixture of a plurality of compounds, and then the mixing ratio of each compound in the mixture. It is calculated by weighting by (mass ratio).
The log P value is a value measured by a flask shaking method described in JIS Z-7260-107: 2000. Further, the logP value may be a value estimated by a computational chemical method or an empirical method instead of the actual measurement.

  When the log P value is obtained by a computational chemistry method, the calculation method includes Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, p21 (1987)), Viswanadhan's fragmentation method ( J. Chem. Inf. Comput. Sci., 29, p163 (1989)), Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, p71 (1984)). ClogP method (reference documents Leo, A., Jow, PYC, Silipo, C., Hansch, C., J. Med. Chem., 18, 865 1975) and the like are preferably used. Crippen's flag Mention method (J. Chem. Inf. Comput. Sci., 27, p21 (1987)) is preferred. However, when the measured value by the flask shaking method mentioned above and the value estimated by the computational chemical method or the empirical method are significantly different, the measured value by the flask shaking method has priority.

  The average log P value of the hydrolysis inhibitor used in the present invention is preferably 7.5 or more, more preferably 8.0 or more, still more preferably 9.0 or more, and particularly preferably 9.5. That's it. When the average log P value of the hydrolysis inhibitor is within such a range, an excellent hydrolysis prevention effect can be exhibited even with a small addition amount. For this reason, generation | occurrence | production of the bleedout etc. which generate | occur | produce when the additive must be added in large quantities can be prevented. On the other hand, although there is no restriction | limiting in particular about the upper limit of the average logP value of a hydrolysis inhibitor, Usually, it is preferable that it is about 13.0 or less from a viewpoint of compatibility with a cellulose acylate.

The specific form of the hydrolysis inhibitor that can be used in the present invention is not particularly limited as long as the definition of the hydrolysis inhibitor described above is satisfied, and preferably the preferable range of the log P value described above is also satisfied. An example of the hydrolysis inhibitor is a sugar ester compound represented by the following general formula (II).
Formula _{(II) (HO) m -G-} (O-C (= O) -R 2) l
[In formula, G represents the residue of a monosaccharide or a disaccharide. R ² represents an aliphatic group or an aromatic group. m represents the total number of hydroxy groups directly bonded to the monosaccharide or disaccharide residues. l represents the total number of — (O—C (═O) —R ² ) groups directly bonded to the monosaccharide or disaccharide residue, 3 ≦ m + l ≦ 8, and l ≠ 0. . ]

The compound having the structure represented by the general formula (II) is a single type of compound in which the total number m of hydroxy groups and the total number l of — (O—C (═O) —R ² ) groups are fixed. It is difficult to separate, and it is known that a compound in which several components different in m and l in the formula are mixed is obtained. Therefore, the number of hydroxy groups m, - is (O-C (= O) -R 2) performance as a mixture number l is changed each group is important.
In the case of the cellulose acylate film of the present invention, the mixing ratio of the component represented by the general formula (II) and the component m = 0 and the component m> 0 is 45:55 with respect to the haze characteristics. Compounds that are in the range of ~ 0: 100 are preferred. More preferably, in terms of performance and cost, the mixing ratio of the component m = 0 and the component m> 0 is in the range of 10:90 to 0.1: 99.9. In addition, the component of m = 0 and the component of m> 0 can be measured by high performance liquid chromatography by a conventional method.

  Specific examples of the monosaccharide of the residue represented by G in the general formula (II) include, for example, allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, lyxose, and the like. .

Examples of the structure of the compound having a monosaccharide residue represented by the general formula (II) are shown below, but the present invention is not limited to these specific examples.

Specific examples of the disaccharide of the residue represented by G include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and isotrehalose.
Although the structural example of the compound which has a disaccharide residue represented by general formula (II) below is shown, this invention is not limited to these specific examples.

In general formula (II), the aliphatic group or aromatic group represented by R ² may each independently have a substituent.

In the general formula (II), m and l are required to satisfy 3 ≦ m + l ≦ 8, and preferably 4 ≦ m + l ≦ 8. Also, l ≠ 0. In addition, when l is 2 or more, the — (O—C (═O) —R ² ) groups may be the same or different.

The aliphatic group in the definition of R ^{2 in} the general formula (II) may be linear, branched or cyclic. The aliphatic group preferably has 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 2 to 15 carbon atoms. Specific examples of the aliphatic group include, for example, methyl, ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, iso-butyl, tert-butyl, amyl, iso-amyl, tert-amyl, and n-hexyl. Cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, tert-octyl, dodecyl, hexadecyl, octadecyl, didecyl and the like.

In addition, the aromatic group in the definition of R ^{2 in} the general formula (II) may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group. The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Specific examples of the aromatic hydrocarbon group include benzene, naphthalene, anthracene, biphenyl, terphenyl and the like. As the aromatic hydrocarbon group, benzene, naphthalene, and biphenyl are particularly preferable. As an aromatic heterocyclic group, what contains at least 1 among an oxygen atom, a nitrogen atom, or a sulfur atom is preferable. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline. Phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. As the aromatic heterocyclic group, pyridine, triazine, and quinoline are particularly preferable.

Next, although the preferable example of a compound represented by general formula (II) is shown below, this invention is not limited to these specific examples.

Hereinafter, synthesis examples of the compound represented by the general formula (II) are shown.
A four-headed colben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was mixed with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas from 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 was added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer was collected, and toluene was distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). The mixture of exemplary compound (C-1), (C-2), (C-3), (C-4) and (C-5) was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, (C-1) was 7% by mass, (C-2) was 58% by mass, (C-3) was 23% by mass, and (C-4). Was 9% by mass, and (C-5) was 3% by mass. In addition, by purifying a part of the obtained mixture by silica gel column chromatography, (C-1), (C-2), (C-3), (C-4), and (C-4) having a purity of 100%, respectively. C-5) was obtained.

  The hydrolysis inhibitor that can be added to the cellulose acylate film according to one embodiment of the present invention exhibits the effect of imparting water resistance to the film as described above. Therefore, it is preferable that the hydrolysis inhibitor is uniformly distributed throughout the film as much as possible, unlike the Tg reducing agent described above.

〔式中、ｍａｘ｛ｄ_Ｃ，ｄ_Ｄ｝はｄ_Ｃ又はｄ_Ｄのうち大きい方を表し、ｍｉｎ｛ｄ_C，ｄ_D｝はｄ_C又はｄ_Dのうち大きくない方を表す。〕Expressing this quantitatively, when the detected values of the hydrolysis inhibitor on both sides of the film, detected using time-of-flight secondary ion mass spectrometry, are d _C and d _D , respectively, The s value indicated by (2) is preferably less than 1.1.

[Wherein, max {d _C , d _D } represents the larger of d _C or d _D , and min {d _C , d _D } represents the smaller of d _C or d _D. ]

  As can be understood from the above description of the deviation of the detected value of the Tg reducing agent, this preferred embodiment of the deviation of the detected value of the hydrolysis inhibitor is, This means that the detected value of the hydrolysis inhibitor by secondary ion mass spectrometry is almost non-biased, specifically, only to the extent that the ratio is less than 1.1.

  In a preferred embodiment, the s value is theoretically a real number of 1 or more. The s value may be less than 1.1, but the s value is preferably 1.05 or less, more preferably 1.03 or less, still more preferably 1.02 or less, and particularly preferably 1. 01 or less, and most preferably 1.005 or less.

(Plasticizer)
In order to obtain the effects of the present invention, the cellulose acylate film of the present invention may contain a conventionally known plasticizer as necessary. Although the compound represented by the general formula (I) or the general formula (II) described above is also used as a plasticizer, it can also contain other plasticizers.
The specific form of the other plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, or a polyhydric alcohol ester. Selected from plasticizers, ester plasticizers, acrylic plasticizers, and the like. Of these, when two or more plasticizers are used, at least one of them is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising a dihydric or higher aliphatic polyhydric alcohol and an ester of a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

The polyhydric alcohol preferably used in the present invention is represented by the following general formula (III).
Formula _{(III) R 11 - (OH} ) n
[Wherein R ₁₁ represents an n-valent organic group. n represents an integer of 2 or more. The OH group represents an alcoholic and / or phenolic hydroxy group. ]

  Preferred polyhydric alcohols include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2 -Butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol Mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.
As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with cellulose acylate is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.
Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as an alkyl group, a methoxy group or an ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferable because it is less likely to volatilize, and a lower molecular weight is preferable in terms of moisture permeability and compatibility with cellulose acylate.
The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

Specific examples of the polyhydric alcohol ester compounds (ae-1) to (ae-35) are shown below.

The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.
Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.
Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.
The polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably 2 to 20 valent polyvalent carboxylic acid and an alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

The polyvalent carboxylic acid is represented by the following general formula (IV).
Formula (IV) R ₁₂ (COOH) _m1 (OH) _n1
[Wherein R ₁₂ represents an (m1 + n1) -valent organic group, m1 represents an integer of 2 or more, n1 represents an integer of 0 or more, a COOH group represents a carboxy group, an OH group represents an alcoholic group and / or Or represents a phenolic hydroxy group. ]

Examples of the preferred polyvalent carboxylic acid include the following, but the present invention is not limited thereto.
Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving the retention.

There is no restriction | limiting in particular as alcohol used for a polyhydric carboxylic acid ester compound, Well-known alcohol and phenols can be used.
For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.
When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxy group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid.

Although there is no restriction | limiting in particular in the molecular weight of a polyhydric carboxylic acid ester compound, It is preferable that it is the range of molecular weight 300-1000, and it is more preferable that it is the range of 350-750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose acylate.
The alcohols used in the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.
The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

  In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxy group which exists in a sample) contained in 1g of samples. As the acid value, a value measured in accordance with JIS K0070 is adopted.

Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.
For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

(UV absorber)
The cellulose acylate film of the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is added for the purpose of improving the durability of the cellulose acylate film by absorbing ultraviolet rays of 400 nm or less. The transmittance at a wavelength of 370 nm in the cellulose acylate film is preferably 10% or less, more preferably 5% or less, and further preferably 2% or less.

Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.
For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products made by BASF Japan and can be preferably used.

The ultraviolet absorber preferably used in the present invention is a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, or a triazine ultraviolet absorber, and particularly preferably a benzotriazole ultraviolet absorber or a benzophenone ultraviolet absorber.
In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.
The method for adding the UV absorber is to add the UV absorber to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof. Or you may add directly in dope composition.

For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose acylate to disperse and then added to the dope.
The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry thickness of the cellulose acylate film is 30 to 200 μm, the amount used is 0.5 to the total mass of the film. -10.0 mass% is preferable, and 0.6-4.0 mass% is further more preferable.

(Antioxidant)
Antioxidants are also referred to as deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the cellulose acylate film may be deteriorated.
The antioxidant has a role of delaying or preventing the cellulose acylate film from being decomposed by, for example, the residual solvent amount of halogen in the cellulose acylate film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain in an acylate film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.
The amount of these compounds added is preferably 1 to 5000 ppm, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose acylate film.

(Acid scavenger)
Since cellulose acylate is accelerated by acid at high temperatures, it is preferable to contain an acid scavenger when used for the cellulose acylate film of the present invention.
Any useful acid scavenger can be used without limitation as long as it is a compound that reacts with an acid to inactivate the acid. Among them, the epoxy described in US Pat. No. 4,137,201 is particularly useful. Compounds having a group are preferred.

  Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of diglycidyl ethers of various polyglycols, particularly about 8-40 moles of ethylene oxide per mole of polyglycol. Examples include polyglycol and diglycidyl ether of glycerol. Also, in or together with the vinyl chloride polymer composition, metal epoxy compounds, epoxidized ether condensation products, diglycidyl ethers of bisphenol A (ie, 4,4′- Dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester and the like can also be mentioned. The epoxidized unsaturated fatty acid ester is particularly preferably an ester of a fatty acid having 2 to 22 carbon atoms and an alcohol having 2 to 4 carbon atoms, such as butyl epoxy stearate. Others include epoxidized vegetable oils and other unsaturated natural oils that may be represented and exemplified by compositions such as various epoxidized long chain fatty acid triglycerides such as epoxidized soybean oil. These fats and oils are also called epoxidized natural glycerides or unsaturated fatty acids, and the fatty acids of these fats and oils generally contain 12 to 22 carbon atoms. Moreover, EPON 815C can also be preferably used as a commercially available epoxy group-containing epoxide resin compound.

Further, acid scavengers that can be used other than the above are oxetane compounds, oxazoline compounds, organic earth salts of alkaline earth metals, acetylacetonate complexes, and paragraphs 0068 to 0105 of JP-A-5-194788. Are included.
In addition, although an acid scavenger may be called an acid scavenger, an acid capture agent, an acid catcher, etc., in this invention, it can use without a difference by these names.

(Fine particles)
The cellulose acylate film of the present invention has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, silicic acid in order to improve handleability. It is preferable to contain a matting agent such as inorganic fine particles such as aluminum, magnesium silicate and calcium phosphate, and a crosslinked polymer. Of these, silicon dioxide is preferable because haze of the cellulose acylate film can be reduced.

The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.
These fine particles are preferably contained in the cellulose acylate film by forming secondary particles having an average particle diameter of 0.1 to 5.0 μm, and more preferably the average particle diameter is 0.1 to 2.0 μm. More preferably, it is 0.2 to 0.6 μm. Thereby, the unevenness | corrugation of height about 0.1-1.0 micrometer can be formed in the surface of a cellulose acylate film, and appropriate slipperiness can be given to the surface by an unevenness | corrugation.

  The primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. Let the value be the primary average particle size.

<Method for producing cellulose acylate film>
The method for producing a cellulose acylate film used in the present invention includes a step of stretching a film obtained by casting a dope on a metal support, drying the film, and peeling the film. Since the dope essentially includes a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 and a Tg reducing agent, the abundance of the Tg reducing agent on both surfaces of the obtained cellulose acylate film is to some extent. The above steps are performed so that they are biased.

The method for producing a cellulose acylate film may be a method by a solution casting method or a method by a melt casting method, but is preferably a method by a solution casting method.
Hereinafter, although the manufacturing method of the cellulose acylate film by a solution casting method is mentioned as an example and demonstrated, it is not limited to the following form.

  The cellulose acylate film is produced by the solution casting method, for example, by dissolving cellulose acylate having an acyl group substitution degree of 2.0 to 2.5, a Tg reducing agent, and other additives as required in a solvent. A step of preparing a dope, a step of casting the dope on an endless metal support that moves infinitely, a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, Furthermore, the process of drying and the process of winding up the finished film are passed.

First, the process for preparing the dope will be described.
The concentration of cellulose acylate in the dope is preferable because it can reduce the drying load after casting on the metal support, but if the concentration of cellulose acylate is too high, the load during filtration increases and the filtration accuracy Becomes worse. The concentration for achieving both of these is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass. As for the Tg lowering agent and other additives, it is preferable to batch add a specified amount to the dope preparation kettle.

  The solvent used for the preparation of the dope may be used alone or in combination of two or more, but it is preferable in terms of production efficiency to use a mixture of a good solvent and a poor solvent of cellulose acylate, A larger amount of good solvent is preferred from the viewpoint of the solubility of cellulose acylate.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, the solvent which dissolves the cellulose acylate to be used alone is defined as a good solvent, and a solvent which swells alone or does not dissolve is defined as a poor solvent. Therefore, the good solvent and the poor solvent change depending on the acyl group substitution degree of cellulose acylate.

  The good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2.00 mass% water is contained in dope.

The solvent used for dissolving cellulose acylate can be reused by collecting the solvent removed from the film by drying in the film-forming process.
The recovered solvent may contain trace amounts of additives added to cellulose acylate, such as plasticizers, UV absorbers, polymers, monomer components, etc. Can be purified and reused if necessary.

As a method for dissolving cellulose acylate when preparing the dope, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.
It is preferable to stir and dissolve while heating at a temperature not lower than the boiling point at normal pressure of the solvent and under pressure so that the solvent does not boil, because it is possible to prevent the formation of a bulk undissolved material called gel or mamako.

Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.
The heating temperature with the addition of the solvent is preferably higher from the viewpoint of the solubility of cellulose acylate, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.
The range of preferable heating temperature is 45-120 degreeC, 60-110 degreeC is more preferable, and 70-105 degreeC is further more preferable.
The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. The pressure is adjusted so that the solvent does not boil at the set temperature.

As a method for dissolving cellulose acylate, a method in which cellulose acylate is mixed with a poor solvent and wetted or swollen, and then a good solvent is further added and dissolved is preferably used.
In addition, a cooling dissolution method is also preferably used, whereby cellulose acylate can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose acylate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but from the viewpoint of suppressing the occurrence of clogging of the filter medium, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable. A filter medium of 001 to 0.008 mm is more preferable, and a filter medium of 0.003 to 0.006 mm is more preferable.

There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel can cause fibers to fall off. Less preferred.
It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acylate by filtration.

Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. The point (foreign matter) that the light from the opposite side appears to leak.
The number of bright spot foreign matters having a diameter of 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, further preferably 50 pieces / m ² or less, Most preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spot foreign matters having a diameter of 0.01 mm or less is small.

The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and under a pressure in a range where the solvent does not boil is the filtration pressure before and after filtration. The increase in the difference is small and preferable.
A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C.
A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

Here, as described above, a series of steps is performed so that the existing amount of the Tg reducing agent on both surfaces of the obtained cellulose acylate film is biased to some extent. Specifically, as the produced cellulose acylate film detection value d _A of the Tg-lowering agent in the bonding surface and the other surface of the _polarizer, r values determined from d _B becomes 1.1 or more In addition, the above-described series of steps is performed.

  There is no particular limitation on a specific method for performing the above steps so that the r value is 1.1 or more, and various methods can be adopted. Hereinafter, three typical embodiments (first to third embodiments) will be described, but the present invention is not limited to such embodiments.

(First form)
In the first embodiment, the above process can be performed by selecting various materials when preparing the dope. Specifically, as the essential components of the dope, there are three components, cellulose acylate, Tg lowering agent, and solvent. The material is selected so that the solubility parameter value of each of these three components satisfies a predetermined relationship. select. Thereby, it was found that the distribution of the Tg reducing agent can be biased in the thickness direction in the obtained cellulose acylate film. More specifically, when the Hansi solubility parameters of cellulose acylate, Tg lowering agent and solvent are HSP _C , HSP _G and HSP _S in this order, the following formula (4) is satisfied. Each material may be selected.
Formula (4) | HSP _G -HSP _C |> | HSP _G -HSP _S |

The Hansen Solubility Parameter (HSP) is a parameter developed by Charles Hansen to indicate the solubility of a substance. The Hansen solubility parameters HSP _C , HSP _G , and HSP _S are described in Hansen, Charles (2007). Hansen Solubility Parameters: Values measured by the method described in A user's handbook, Second Edition are adopted. In addition, there may be a form in which the cellulose acylate, the Tg lowering agent and the solvent are each a mixture of two or more, but the values of HSP _C , HSP _G and HSP _S in such a form are measured as a mixture. Adopted values.

Briefly the technical significance of the above equation _{(4), | HSP G -HSP} C | is the absolute of the difference between the value HSP _C solubility parameter values HSP _G cellulose acylate solubility parameter of Tg-lowering agent Mean value. On the other hand, | HSP _G -HSP _S | means the absolute value of the difference between the solubility parameter value HSP _G of the Tg reducing agent and the solubility parameter value HSP _S of the solvent. Then, the fact that equation (4) is satisfied, the former is larger than the latter, that is, the value HSP _G solubility parameter of Tg-lowering agent, close to the value HSP _S of solvent than the value HSP _C of the cellulose acylate Means.

  When the material is selected so as to satisfy Equation (4), in the obtained cellulose acylate film, the mechanism by which the distribution of the Tg reducing agent is biased in the thickness direction of the film is not completely clear, but the solubility parameters are close. Since it means that the solubility (affinity) is higher, the following mechanism has been estimated. That is, when dried on the metal support, the solvent gradually evaporates from the surface not in contact with the metal support (interface with air), so the concentration of the solvent in the thickness direction of the cellulose acylate film A gradient occurs. At that time, if the affinity of the Tg lowering agent for the solvent is higher than the affinity for the cellulose acylate, it is considered that the Tg lowering agent is biased toward the metal support having a higher solvent concentration.

When the solubility parameter values HSP _C , HSP _G , and HSP _S satisfy the above formula (4), | HSP _G −HSP _C | is preferably 1.1 times or more of | HSP _G −HSP _S |. 1.2 times or more is more preferable, and 1.5 times or more is more preferable. By setting it as such a range, it becomes possible to express the bias | inclination of the distribution of the thickness direction of the Tg reducing agent in the manufactured cellulose acylate film reliably.

Next, dope casting will be described.
The metal support used in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to less than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. However, if the temperature is too high, the web may foam or the flatness may deteriorate.
The range of preferable support body temperature is 0-55 degreeC, and 25-50 degreeC is still more preferable.
It is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use hot water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is shortened. When warm air is used, wind at a temperature higher than the target temperature may be used.

Next, the film obtained by casting is dried and peeled off.
Here, as a second embodiment in which the distribution of the Tg reducing agent is biased in the thickness direction in the cellulose acylate film, there is a method of controlling the process conditions after casting the dope on the metal support.
Specifically, the amount of residual solvent in the film at the time of peeling the film from the metal support is reduced. That is, it has been found that by drying under more severe conditions, it is possible to make the distribution of the Tg reducing agent biased in the thickness direction in the obtained cellulose acylate film.

  More specifically, the process conditions may be controlled so that the residual solvent amount in the film at the time of peeling from the metal support is 90% or less. The amount of residual solvent in the film at the time of peeling from the metal support is preferably 85% or less, more preferably 80% or less. In addition, the control according to the second mode and the control according to the first mode (selection of material at the time of dope preparation) described above may be performed together. Of course, it is possible to produce a cellulose acylate film having an uneven distribution of the Tg reducing agent by controlling only one of them.

The amount of residual solvent is defined by the following formula 5.
Formula (5) Residual solvent amount (% by mass) = {(MN) / N} × 100
[In the formula, M represents the mass of a sample collected at any time during or after production of the web or cellulose acylate film, and N represents the mass after heating the sample at 115 ° C. for 1 hour. ]

  Examples of the process conditions that are controlled so that the value of the residual solvent amount is not more than a predetermined value include drying conditions before the film is peeled off from the metal support. There is no particular limitation on the specific form of drying conditions before film peeling from the metal support, and controlling the drying conditions so that the value of the residual solvent amount of the film at the time of peeling is not more than a predetermined value, Those skilled in the art can carry out the present invention without any particular difficulty. If an example of drying conditions is given, the range of drying temperature becomes like this. Preferably it is about 25-50 degreeC, More preferably, it is 35-45 degreeC. The drying time is preferably about 15 to 150 seconds, more preferably 25 to 120 seconds. Of course, if the value of the residual solvent amount of the film at the time of peeling is not more than a predetermined value, conditions outside these ranges may be adopted.

  There is no restriction | limiting in particular about the drying means employ | adopted in a drying process, A well-known knowledge can be referred suitably. Specific examples of the drying means include hot air, infrared rays, heating rollers, and microwaves, but it is preferable to carry out with hot air from the viewpoint of simplicity.

  Next, the film (web) peeled from the metal support is stretched. Under the present circumstances, it is especially preferable to extend | stretch in the width direction (direction orthogonal to the film forming direction within the surface of a film) by the tenter system which hold | grips both ends of the peeled film (web) with a clip etc. The peel tension from the metal support is preferably 300 N / m or less.

By adjusting the conditions during the stretching treatment, the film thickness and retardation value of the obtained cellulose acylate film can be controlled.
For example, the retardation can be changed by lowering or increasing the tension in the longitudinal direction. Moreover, retardation can be fluctuate | varied by carrying out biaxial stretching or uniaxial stretching sequentially or simultaneously with respect to the longitudinal direction (it is also called the film forming direction or casting direction) and the width direction of a film.

The draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 0.8 to 1.5 times in the longitudinal direction and 1.1 to 2.0 times in the width direction, respectively. It is more preferable to carry out in the range of 0.8 to 1.1 times and 1.3 to 1.7 times in the width direction, and particularly preferably in the range of 1.3 to 1.5 times in the width direction.
The cellulose acylate film of the present invention is easily stretched and retardation is likely to develop, and has high resistance to process failures such as breakage.

  As for the temperature range at the time of extending | stretching, 120 to 200 degreeC is preferable, More preferably, it is 130 to 170 degreeC, More preferably, it exceeds 140 degreeC and is 160 degrees C or less. The range of the residual solvent amount in the film during the stretching treatment is preferably 20 to 0%, more preferably 15 to 0%. More specifically, for example, it is preferable that the residual solvent amount is stretched by 11% at a temperature of 155 ° C., or the residual solvent amount is stretched by 2% at a temperature of 155 ° C. Alternatively, it is preferable to stretch at a temperature of 160 ° C. with a residual solvent amount of 11%, or at 160 ° C. with a residual solvent amount of less than 1%.

  There is no particular limitation on the method of stretching the web. For example, a method in which a circumferential speed difference is applied to a plurality of rollers and the longitudinal speed difference is used to stretch in the longitudinal direction, both ends of the web are fixed with clips and pins, and the distance between the clips and pins is widened in the traveling direction. Examples thereof include a method of stretching in the direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.

In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the possibility of breakage or the like can be reduced.
It is preferable to carry out the width maintenance or lateral stretching in the film forming step by a tenter, and it may be a pin tenter or a clip tenter.

After the stretching described above, a further drying step is preferably performed so that the residual solvent amount is 1% by mass or less, more preferably 0.10% by mass or less, and further preferably 0.00 to 0.01% by mass. It is as follows.
The drying temperature after stretching is preferably 125 ° C. or higher, and more preferably 140 ° C. or higher. If it exceeds 150 ° C., it approaches the glass transition temperature Tg of the cellulose acylate film, which may lead to a decrease in retardation value or misalignment of the orientation angle.

  The manufacturing method by the solution casting method has been described above as an example, but from the viewpoint of manufacturing cost, the manufacturing method may be performed by the melt casting method. In this case, a desired cellulose acylate film can be obtained by the control according to the second embodiment described above.

  Without using the solvent used in the solution casting method (for example, methylene chloride, etc.), the molding method by melt casting that is heated and melted is a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, It can be classified into a stretch molding method. Among these, in order to obtain a cellulose acylate film excellent in mechanical strength, surface accuracy and the like, the melt extrusion molding method is excellent. There is no particular limitation on the specific method for obtaining the cellulose acylate web by the melt casting method, and known knowledge can be referred to as appropriate.

In addition to the solution casting method and the melt casting method, a cellulose acylate film in which the distribution of the Tg reducing agent is biased in the thickness direction can be produced by a co-casting method.
Hereinafter, as a third embodiment in which the distribution of the Tg reducing agent in the cellulose acylate film is biased in the thickness direction, a method for producing a cellulose acylate film by a co-casting method will be described. Specifically, the manufacturing method according to the third embodiment includes a step of co-casting a plurality of dopes having different Tg lowering agent concentrations on a metal support, drying a film obtained by casting, and peeling the film. And a step of stretching after.

(Third form)
First, a plurality of dopes including a cellulose acylate, a Tg reducing agent, and other additives are prepared. When two co-cast dopes are prepared, a dope A having a low concentration of Tg reducing agent and a dope B having a high concentration of Tg reducing agent are prepared. Dope A is on the surface layer side, and dope B is on the metal support layer side. What is necessary is just to co-cast on a metal support body so that it may become. When co-casting three or more dopes having different Tg lowering agent concentrations, the respective dopes are laminated from the surface layer side to the metal support layer side in the order of increasing Tg reducing agent concentration. The form of performing is preferable. In addition, there is no restriction | limiting in particular about the specific value of the density | concentration of the Tg reducing agent in dope in this 3rd form, What is necessary is just to adjust suitably in consideration of the retardation value of the whole cellulose acylate film obtained.

<Physical properties of cellulose acylate film>
The film thickness of the cellulose acylate film used in the present invention is preferably a thin film, a range of 10 to 200 μm is used, preferably 10 to 100 μm, more preferably 10 to 60 μm, and still more preferably. Is 20-60 μm.
The width of the cellulose acylate film used in the present invention is 1.0 to 4.0 m. In particular, a width of 1.4 to 4.0 m is preferable, and 1.6 to 3.0 m is more preferable. When the width is 4.0 m or less, the conveyance is easy.

The retardation values Ro and Rth of the cellulose acylate film used in the present invention are determined by the following mathematical formulas (6) and (7).
Equation _{(6) Ro = (n x} -n y) × d [nm]
Equation _{(7) Rth = {(n} x + n y) / 2-n z} × d [nm]
Wherein, n _x represents a refractive index in a slow axis direction of the cellulose acylate film plane. n _y represents a fast axis direction of the refractive index of the cellulose acylate film plane. _nz represents the refractive index in the thickness direction of the cellulose acylate film. The refractive index is a value measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. d represents the thickness (nm) of the cellulose acylate film. ]

  The retardation values Ro and Rth were obtained by cutting a sample 35 mm × 35 mm from the obtained cellulose acylate film, adjusting the humidity at 25 ° C. × 55% RH for 2 hours, and using an automatic birefringence meter (KOBRA21DH, manufactured by Oji Scientific Co., Ltd.). ) And the extrapolated value of the retardation value measured in the same manner while tilting the cellulose acylate film surface.

Although the retardation required for the cellulose acylate film used in the present invention differs depending on the required optical compensation effect, the retardation values Ro and Rth satisfy the following ranges from the viewpoint of taking advantage of high retardation development. Is preferred.
10 ≦ Ro ≦ 100
70 ≦ Rth ≦ 300
Here, retardation value Ro becomes like this. Preferably it is 30-70, More preferably, it is 40-60, More preferably, it is 45-55.
Moreover, retardation value Rth becomes like this. Preferably it is 90-230, More preferably, it is 100-170, More preferably, it is 110-160.

  When the slow axis or the fast axis of the cellulose acylate film is present in the cellulose acylate film plane and the angle formed with the film forming direction is θ1, it is preferable that θ1 is −1 ° or more and + 1 ° or less. More preferably, it is −0.5 ° or more and + 0.5 ° or less.

  This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). When each θ1 satisfies the above range, it is possible to contribute to obtaining high luminance in the display image, suppressing or preventing light leakage, and obtaining faithful color reproduction in the color liquid crystal display device.

Moisture permeability of the cellulose acylate film, 40 ° C., preferably 300~1800g ^/ m 2 · 24h at 90% RH, further 400~1500g ^/ m 2 · 24h, and particularly preferably 400~1300g ^/ m 2 · 24h is . The moisture permeability can be measured according to the method described in JIS Z0208.

The range of the elongation at break of the cellulose acylate film is preferably 10 to 80%, and more preferably 20 to 50%.
The range of visible light transmittance of the cellulose acylate film is preferably 90% or more, and more preferably 93% or more.
The haze of the cellulose acylate film is preferably less than 1.0%, and more preferably 0.0 to 0.1%.

<Photocurable adhesive>
Preferable examples of the photocurable adhesive for bonding the polarizer and the cellulose acylate film include a photocurable adhesive composition containing the following components (α) to (δ). .

(Α) Cationic polymerizable compound (β) Photocationic polymerization initiator (γ) Photosensitizer exhibiting maximum absorption in light having a wavelength longer than 380 nm (δ) Naphthalene photosensitizer

(Cationically polymerizable compound (α))
The cationically polymerizable compound (α), which is a main component of the photocurable adhesive composition and serves as a component that gives adhesive force by polymerization and curing, may be any compound that can be cured by cationic polymerization. It is preferable to include an epoxy compound having one epoxy group. 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 photocurable adhesive composition used in the present invention is preferably an epoxy resin containing no aromatic ring, particularly an alicyclic epoxy compound as a main component, as the cationic polymerizable compound (α). If a cationically polymerizable compound containing an alicyclic epoxy compound as a main component is used, a cured product having a high storage elastic modulus is given, and the cellulose acylate film and the polarizer are bonded via the cured product (adhesive layer). In the polarizing plate, the polarizer is difficult to break.

As described above, 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 one or more hydrogen atoms in (CH ₂ ) _m in the general formula (ep) are removed and 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. Among these, a compound having an epoxycyclopentane ring (m = 3 in the general formula (ep)) or an epoxycyclohexane ring (m = 4 in the general formula (ep)) is preferable.

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

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 an ester compound 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 formula (ep-2), R ⁵ = 6-methyl, R ⁶ = 6-methyl, n = 0 A certain compound).

〔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。〕

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 cellulose acylate 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 large effect of improving the adhesion between the polarizer and the cellulose acylate film.

[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 of the general formula (ge) include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol S; glycidyl ether of tetrahydroxyphenylmethane , Glycidyl ether of tetrahydroxybenzophenone, polyfunctional epoxy resin such as epoxidized polyvinylphenol; polyglycidyl ether of aliphatic polyhydric alcohol; polyglycidyl ether of alkylene oxide adduct of aliphatic polyhydric alcohol; Examples thereof include diglycidyl ether, and among them, polyglycidyl ether of aliphatic polyhydric alcohol is preferable because it is easily available.

  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 1,000 MPa or more, and such a cured product (adhesive layer) is obtained. In the polarizing plate in which the polarizer and the cellulose acylate film are bonded to each other, the polarizer is hardly broken. Moreover, the adhesiveness of a polarizer and a cellulose acylate 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 permissible up to mass%, it is preferable to make it 45 mass% or less on the basis of the total amount of the cationic polymerizable compound from the viewpoint of suppressing a decrease in storage elastic modulus of the cured product and preventing cracking of the polarizer.

  As the cationically polymerizable compound (α) constituting the photocurable adhesive composition, when using an alicyclic epoxy compound and an epoxy resin substantially free of an alicyclic epoxy group as described above, In the range where becomes the above-mentioned amount, in addition to these, other cationically polymerizable compounds may be included. 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 in the molecule. Diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol S, glycidyl ether of phenol novolac resin, 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, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (cyclohexyloxymethyl) oxetane, phenol novolak 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 photocurable adhesive composition has photocationic polymerization initiation. It is preferable to blend the agent (β).

  The cationic photopolymerization initiator (β) generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and performs a polymerization reaction of the cationic polymerizable compound (α). It is what is started. Since the cationic photopolymerization initiator (β) 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 aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis [diphenylsulfonio] diphenyl sulfide bishexafluoro. 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexa Fluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio ] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio -Diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

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

  These cationic photopolymerization initiators (β) 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 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 (β) 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 can be obtained. Gives high mechanical strength and 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).

〔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。〕(Photosensitizer (γ))
The photocurable adhesive composition that can be used in the present invention is suitable 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.

[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 mix | blending the above photosensitizers ((gamma)) with a photocurable adhesive composition, the sclerosis | hardenability of a photocurable adhesive composition improves compared with the case where it is not mix | blended. Curability is improved by setting the blending amount of the photosensitizer (γ) to 100 parts by mass of the cationic polymerizable compound (α) constituting the photocurable adhesive composition to be 0.1 parts by mass or more. The effect is manifested. On the other hand, in order to prevent precipitation during low-temperature storage, the blending amount is 2 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable compound (α). From the viewpoint of maintaining the neutral gray of the polarizing plate, it is advantageous to reduce the blending amount of the photosensitizer (γ) as long as the adhesiveness between the polarizer and the cellulose acylate 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.

〔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。〕(Photosensitizer (δ))
The photocurable adhesive composition that can be used in the present invention includes the following cationic polymerizable compound (α) containing an epoxy compound, a cationic photopolymerization initiator (β), and a photosensitizer (γ). It contains a naphthalene-based photosensitization aid (δ) represented by the general formula (nf).

[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.

  By mix | blending a naphthalene type photosensitization adjuvant ((delta)) with a photocurable adhesive composition, the sclerosis | hardenability of a photocurable adhesive composition improves compared with the case where it is not mix | blended. By setting the blending amount of the naphthalene photosensitizer (δ) to 100 parts by mass of the cationic polymerizable compound (α) constituting the photocurable adhesive composition to be 0.1 parts by mass or more, curability is improved. The improvement effect is manifested. On the other hand, the amount of the naphthalene-based photosensitization aid (δ) is 10 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable compound (α) in order to prevent precipitation during low-temperature storage. 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 photocurable adhesive composition that can be used in the present invention can contain an additive component as 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), and a photosensitizer, which are essential components of the photocurable adhesive composition that can be used in the present invention. By combining (γ) and the photosensitizing aid (δ), the effects of improving storage stability, preventing discoloration, improving curing speed, and ensuring good adhesion can be exhibited well.

Other preferable examples of the adhesive for laminating the polarizer and the cellulose acylate film include a photocurable adhesive that essentially contains the following three components (α1), (α2), and (β1). A composition is included.
(Α1) Epoxy compound having at least two epoxy groups in the molecule (α2) Oxetane compound having at least one oxetanyl group in the molecule (β1) Photocationic polymerization initiator

  Hereinafter, the epoxy compound (α1), the oxetane compound (α2), and the photocationic polymerization initiator (β1) are simply referred to as the epoxy compound (α1), the oxetane compound (α2), and the photocationic polymerization initiator, respectively. It is called (β1).

  The mass ratio of the epoxy compound (α1) to the oxetane compound (α2) (epoxy compound (α1): oxetane compound (α2)) is preferably about 90:10 to 10:90. Moreover, it is preferable to mix | blend a photocationic polymerization initiator ((beta) 1) in the ratio of about 0.5-20.0 mass% in a composition.

  The photo-curable adhesive can optionally contain an unsaturated compound having at least one ethylenically unsaturated bond in the molecule as the (ε) component. When such an unsaturated compound (ε) is contained, it is preferable to contain a radical photopolymerization initiator as the (ζ) component. Furthermore, this photocurable adhesive agent can also contain the other component which does not have polymerizability as ((eta)) component.

  The unsaturated compound (ε), the photoradical polymerization initiator as the (ζ) component, and the other non-polymerizable component as the (η) component are simply referred to as the unsaturated compound (ε) and the photoradical, respectively. It is referred to as a polymerization initiator (ζ) and other component (η) having no polymerizability.

(Epoxy compound (α1))
In the photo-curable adhesive composition that can be used in the present invention, the epoxy compound (α1) is not particularly limited as long as it has at least two epoxy groups in the molecule, and various kinds of generally known curings. A functional epoxy compound can be used. As a preferable epoxy compound (α1), an aromatic epoxy compound having at least two epoxy groups and at least one aromatic ring in the molecule, or at least two epoxy groups in the molecule, at least one of them. An example is an alicyclic epoxy compound formed between two adjacent carbon atoms constituting an alicyclic ring.

  The aromatic epoxy compound is not particularly limited as long as the effects of the present invention are not hindered, but bisphenol type such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and brominated bisphenol A diglycidyl ether. Epoxy resins; novolak epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins; biphenyl type epoxy resins, hydroquinone diglycidyl ether, resorcin diglycidyl ether, terephthalic acid diglycidyl ester, phthalic acid diglycidyl ester , Epoxidized styrene-butadiene copolymer, epoxidized styrene-isoprene copolymer, terminal carboxylic acid polybutadiene and bisphenol A type epoxy resin Reactants, and the like as examples.

  The epoxy resin here means a compound or polymer having an average of two or more epoxy groups in the molecule and cured by reaction. In accordance with the practice in this field, a monomer may be referred to as an epoxy resin as long as it has two or more curable epoxy groups in the molecule.

  The alicyclic epoxy compound is not particularly limited as long as the effects of the present invention are not hindered, but dicyclopentadiene dioxide, limonene dioxide, 4-vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl-3,4. Examples include compounds having at least one epoxidized cyclohexyl group such as epoxycyclohexanecarboxylate and bis (3,4-epoxycyclohexylmethyl) adipate.

  In addition to the above, aliphatic epoxy compounds such as 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, polytetramethylene glycol diglycidyl ether; dihydrogenated bisphenol A An epoxy compound such as glycidyl ether in which an aromatic ring is hydrogenated; a compound in which both ends of polybutadiene having both hydroxy groups are glycidyl etherified, an internal epoxidized product of polybutadiene, and a double bond of a styrene-butadiene copolymer A partially epoxidized compound (for example, Epofriend manufactured by Daicel Chemical Industries, Ltd.), a compound in which the isoprene unit of a block copolymer of ethylene-butylene copolymer and polyisoprene is partially epoxidized (for example, KRATON Co. polymeric epoxy compounds such as L-207) or the like may also be epoxy compound ([alpha] 1).

  Among these, aromatic epoxy compounds are preferable because they are excellent in durability when used for polarizing plates, and particularly excellent in adhesion to polarizers and cellulose acylate films. Furthermore, preferred examples of the aromatic epoxy compound include glycidyl ethers of aromatic compounds or glycidyl esters of aromatic compounds. Specific examples of glycidyl ethers of aromatic compounds include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of brominated bisphenol A; phenol novolac type epoxy resin, cresol novolak type Preferred examples include novolak-type epoxy resins such as epoxy resins; biphenyl-type epoxy resins; hydroquinone diglycidyl ether; resorcin diglycidyl ether and the like. Specific examples of glycidyl esters of aromatic compounds include terephthalic acid diglycidyl ester and phthalic acid diglycidyl ester.

  Especially, since the glycidyl ether of an aromatic compound is more excellent in the adhesiveness between a polarizer and a cellulose acylate film, and durability when used for a polarizing plate, it is particularly preferable. Among the glycidyl ethers of aromatic compounds, particularly preferable compounds include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and phenol novolac type epoxy resin.

  As the epoxy compound (α1), one kind can be used alone, or two or more kinds can be mixed and used. For example, two or more aromatic epoxy compounds can be mixed and used, or an aromatic epoxy compound as a main component and an alicyclic epoxy compound can also be mixed.

(Oxetane compound (α2))
In the photocurable adhesive that can be used in the present invention, the oxetane compound (α2) is not particularly limited as long as it has at least one oxetanyl group in the molecule, and various compounds having an oxetanyl group are also used. be able to. Preferred examples of the oxetane compound (α2) include a compound having one oxetanyl group in the molecule (hereinafter referred to as monofunctional oxetane) and a compound having two or more oxetanyl groups in the molecule (hereinafter referred to as polyfunctional oxetane). As mentioned.

  Examples of the monofunctional oxetane include an alkoxyalkyl group-containing monofunctional oxetane such as 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane and an aromatic group-containing monofunctional group such as 3-ethyl-3-phenoxymethyloxetane. Preferred examples include hydroxy group-containing monofunctional oxetanes such as oxetane and 3-ethyl-3-hydroxymethyloxetane.

  Examples of the polyfunctional oxetane include 3-ethyl-3-[(3-ethyloxetane-3-yl) methoxymethyl] oxetane, 1,4-bis [(3-ethyloxetane-3-yl) methoxymethyl] benzene, 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,2-bis [(3-ethyl Oxetane-3-yl) methoxy] benzene, 4,4′-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,2′-bis [(3-ethyloxetane-3-yl) methoxy] Biphenyl, 3,3 ′, 5,5′-tetramethyl-4,4′-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,7-bis [(3-ethyl Xetane-3-yl) methoxy] naphthalene, bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] methane, bis [2-{(3-ethyloxetane-3-yl) methoxy} phenyl] Etherified modification of methane, 2,2-bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] propane, novolak type phenol-formaldehyde resin with 3-chloromethyl-3-ethyloxetane, 3 (4), 8 (9) -bis [(3-ethyloxetane-3-yl) methoxymethyl] -tricyclo [5.2.1.02.6] decane, 2,3-bis [(3-ethyloxetane -3-yl) methoxymethyl] norbornane, 1,1,1-tris [(3-ethyloxetane-3-yl) methoxymethyl] propane, 1- Toxi-2,2-bis [(3-ethyloxetane-3-yl) methoxymethyl] butane, 1,2-bis [{2- (3-ethyloxetane-3-yl) methoxy} ethylthio] ethane, bis [ {4- (3-Ethyloxetane-3-yl) methylthio} phenyl] sulfide, 1,6-bis [(3-ethyloxetane-3-yl) methoxy] -2,2,3,3,4,4,4 Hydrolysis condensate of 5,5-octafluorohexane, 3-[(3-ethyloxetane-3-yl) methoxy] propyltriethoxysilane, condensation of tetrakis [(3-ethyloxetane-3-yl) methyl] silicate Thing etc. are mentioned.

The oxetane compound (α2) is preferably liquid at room temperature with a molecular weight of 500 or less from the viewpoint of coating properties and adhesion to a cellulose acylate film when used for a polarizing plate. Furthermore, in terms of excellent durability of the polarizing plate, a monofunctional oxetane is more preferably an aromatic ring in the molecule or a polyfunctional oxetane. Examples of such preferred oxetane compounds include 3-ethyl-3-phenoxymethyloxetane, 3-ethyl-3-[(3-ethyloxetane-3-yl) methoxymethyl] oxetane, 1,4-bis [(3 -Ethyloxetane-3-yl) methoxymethyl] benzene and the like.
The oxetane compound (α2) can also be used alone or in combination of two or more.

  The mass ratio of the epoxy compound (α1) to the oxetane compound (α2) (epoxy compound (α1): oxetane compound (α2)) is 90:10 to 10:90. If this mass ratio is excessive or insufficient, the effect of curing in a short time, which is one of important characteristics in the photocurable adhesive composition that can be used in the present invention, is not sufficiently exhibited. A preferable mass ratio is about 70:30 to 20:80, more preferably 60:40, because it has a low viscosity before curing, excellent coating properties, and can exhibit sufficient adhesion and flexibility after curing. ~ 25: 75 or so.

(Photocationic polymerization initiator (β1))
The photocurable adhesive composition that can be used in the present invention contains the above-described epoxy compound (α1) and oxetane compound (α2) as curing components, and these are all cured by cationic polymerization. In order to start the cationic polymerization, a photocationic polymerization initiator (β1) is blended. The cationic photopolymerization initiator (β1) generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of an epoxy group or an oxetanyl group.

By blending the cationic photopolymerization initiator (β1), curing at room temperature is possible, and there is little need to consider the heat resistance of the polarizer and distortion due to expansion or contraction, and the cellulose acylate film is adhered well. be able to. In addition, since the cationic photopolymerization initiator (β1) acts catalytically upon irradiation with active energy rays, it is excellent in storage stability and workability even when mixed with the epoxy compound (α1) and the oxetane compound (α2). .
Examples of the photocationic polymerization initiator (β1) that generates cationic species and Lewis acids upon irradiation with such active energy rays include, for example, onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, iron- An allene complex etc. can be mentioned.

  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, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate, diphenyl [ 4- (phenylthio) phenyl] sulfonium hexafluoroantimonate, 4,4′-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl Sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfi Dobishexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p- tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

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

  Each of these cationic photopolymerization initiators (β1) 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 a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.

  As the cationic photopolymerization initiator (β1), commercially available products can be easily obtained. For example, Kayrad PCI-220 and Kayalad PCI-620 (all manufactured by Nippon Kayaku Co., Ltd.) are trade names. UVI-6992 (manufactured by Dow Chemical Co.), Adekaoptomer SP-150, Adekaoptomer SP-170 (above, manufactured by ADEKA), CI-5102, CIT-1370, CIT-1682S, CIP-1866S CIP-2048S, CIP-2064S (manufactured by Nippon Soda Co., Ltd.), DPI-101, DPI-102, DPI-103, DPI-105, MPI-103, MPI-105, BBI-101, BBI-102 , BBI-103, BBI-105, TPS-101, TPS-102, TPS-103, TPS-105, DS-103, MDS-105, DTS-102, DTS-103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia), Irgacure 250, Irgacure PAG103, Irgacure PAG108, Irgacure PAG121, Irgacure PAG203 ( As mentioned above, CPI-100P, CPI-101A, CPI-200K, CPI-210S (above, San Apro Co., Ltd.), etc. are mentioned. Of these, UVI-6992, CPI-100P, CPI-101A, CPI-200K, and CPI-210S containing diphenyl [4- (phenylthio) phenyl] sulfonium as a cation component are preferable.

  The blending ratio of the photocationic polymerization initiator (β1) is in the range of 0.5 to 20.0 mass% based on the entire photocurable adhesive. When the blending ratio is 0.5% by mass or more, the photocurable adhesive is sufficiently cured, and the mechanical strength and the adhesive strength can be maintained. On the other hand, when the blending ratio is 20% by mass or less, an increase in hygroscopicity of the cured product due to an increase in ionic substances in the cured product can be suppressed, and a decrease in durability can be prevented.

(Unsaturated compound (ε))
The photocurable adhesive may contain an unsaturated compound (ε) having at least one ethylenically unsaturated bond in the molecule, if necessary.
A typical example of such an unsaturated compound (ε) is a (meth) acrylic compound having at least one (meth) acryloyl group in the molecule.

  Although it does not specifically limit as a (meth) acrylic-type compound, For example, (meth) acrylates, (meth) acrylamides, (meth) acrylic acid, (meth) acryloylmorpholine, (meth) acrylaldehyde, etc. are mentioned.

  The (meth) acrylates having one (meth) acryloyl group in the molecule (hereinafter referred to as monofunctional (meth) acrylate) are not particularly limited, but for example, methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, Alkyl (meth) acrylates such as stearyl (meth) acrylate; hydrides such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate Xyalkyl (meth) acrylates; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1,4-cyclohexanedimethylol mono (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, di Alicyclic monofunctional (meth) acrylates such as cyclopentenyloxyethyl (meth) acrylate; benzyl (meth) acrylate, (meth) acrylate of p-cumylphenol alkylene oxide adduct, o-phenylphenol alkylene oxide addition (Meth) acrylate, phenolalkylene oxide adduct (meth) acrylate, nonylphenol alkylene oxide adduct (meth) acrylate with a single ring (Meth) acrylates (wherein alkylene oxide includes ethylene oxide, propylene oxide, etc.); 2-methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, alkylene oxide adduct of 2-ethylhexyl alcohol Alkoxyalkyl (meth) acrylates such as (meth) acrylates; such as ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, pentanediol mono (meth) acrylate, hexanediol mono (meth) acrylate Mono (meth) acrylates of dihydric alcohol; mono (meth) acrylate of diethylene glycol, mono (meth) acrylate of triethylene glycol, tetraethyleneglycol Poly (mono) (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate Mono (meth) acrylates of alkylene glycols; glycidyl (meth) acrylates; tetrahydrofurfuryl (meth) acrylates; tetrahydrofurfuryl (meth) acrylates such as caprolactone-modified tetrahydrofurfuryl (meth) acrylates; 3,4-epoxy Examples thereof include cyclohexylmethyl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate; 2- (meth) acryloyloxyethyl isocyanate.

  Moreover, although it does not specifically limit as (meth) acrylates which have a 2 or more (meth) acryloyl group in a molecule | numerator, For example, the following compounds are mentioned.

  Alicyclic rings such as tricyclodecane dimethylol di (meth) acrylate, 1,4-cyclohexane dimethylol di (meth) acrylate, norbornane dimethylol di (meth) acrylate, di (meth) acrylate of hydrogenated bisphenol A Di (meth) acrylates having bisphenol A ethylene oxide adduct di (meth) acrylate, bisphenol A propylene oxide adduct di (meth) acrylate containing di (meth) acrylate, bisphenol A Di (meth) acrylates having an aromatic ring such as di (meth) acrylate of A diglycidyl ether; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, pentane Di (meth) acrylates of alkylene glycols such as all di (meth) acrylate and hexanediol di (meth) acrylate; diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate Di (meth) acrylates of polyalkylene glycols such as polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate; Di- or tri (meth) acrylates, di- or tri (meth) acrylates of glycerol such as di- or tri (meth) acrylate of diglycerol; glycerols Di- or tri (meth) acrylates of alkylene oxide adducts; di (meth) acrylates of bisphenol A alkylene oxide adducts, di (meth) acrylates of bisphenol alkylene oxide adducts (Meth) acrylates; trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipenta Polyol poly (meth) acrylates such as erythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate; these Poly (meth) acrylates of polyol alkylene oxide adducts; di- or tri (meth) acrylates of isocyanuric acid alkylene oxide adducts; 1,3,5-tri (meth) acryloylhexahydro-s-triazine and the like It is done.

  (Meth) acrylamides include 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-hydroxyethyl (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, Examples include mercaaptmethyl (meth) acrylamide and mercaaptethyl (meth) acrylamide.

  In addition, oligomers such as urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate can also be used as the (meth) acrylic compound.

  Furthermore, the compound which has an ethylenically unsaturated bond other than that with a (meth) acryloyl group can also be used as a (meth) acrylic-type compound. Specific examples thereof include allyl (meth) acrylate and N, N-diallyl (meth) acrylamide.

  The unsaturated compound (ε) is not particularly limited, and in addition to the above (meth) acrylic compounds, vinyl compounds such as N-vinyl-2-pyrrolidone, divinyl adipate and divinyl sebacate; triallyl isocyan Allyl compounds such as nurate, triallylamine, tetraallyl pyromellitate, N, N, N ′, N′-tetraallyl-1,4-diaminobutane, tetraallylammonium salt, allylamine; such as maleic acid and itaconic acid Unsaturated carboxylic acids and the like can also be used.

  Of these unsaturated compounds (ε), (meth) acrylic compounds are preferred. Furthermore, when a polarizer and a cellulose acylate film are bonded via an adhesive containing the same to produce a polarizing plate, at least one alicyclic group is included in the molecule from the viewpoint of enhancing durability such as heat resistance. A (meth) acrylic compound having a skeleton or an aromatic ring skeleton is more preferable. Specific examples of the (meth) acrylic compound having at least one alicyclic skeleton or aromatic ring skeleton in the molecule include the above-described alicyclic monofunctional (meth) acrylates and monofunctional having an aromatic ring. Preferable examples include (meth) acrylates, di (meth) acrylates having an alicyclic ring, or di (meth) acrylates having an aromatic ring. Among these, di (meth) acrylate having a tricyclodecane skeleton is preferable, and specific examples of such (meth) acrylic compounds are tricyclodecane dimethylol di (meth) acrylate and the like. be able to.

  The unsaturated compound (ε) can be used to adjust the curing speed, the adhesion between the polarizer and the cellulose acylate film, the elastic modulus of the adhesive layer, the durability of the adhesive, and the like. An unsaturated compound ((epsilon)) can be used individually by 1 type or in mixture of 2 or more types.

  When the unsaturated compound (ε) is blended, the blending ratio is preferably 35% by mass or less based on the entire composition. Thereby, the adhesiveness between a polarizer and a cellulose acylate film becomes excellent. When the amount of the unsaturated compound (ε) is 35% by mass or less, sufficient adhesive strength with the polarizer is easily obtained. Therefore, the blending ratio of the unsaturated compound (ε) is more preferably 30% by mass or less, more preferably about 5 to 25% by mass, particularly preferably about 10 to 20% by mass.

(Photoradical polymerization initiator (ζ))
When the photocurable adhesive contains an unsaturated compound (ε), it is preferable to add a photoradical polymerization initiator (ζ) in order to promote the radical polymerizability and make the curing rate sufficient.

  Specific examples of the radical photopolymerization initiator (ζ) are not particularly limited. For example, 4′-phenoxy-2,2-dichloroacetophenone, 4′-tert-butyl-2,2-dichloroacetophenone, 2,2- Dimethoxy-2-phenylacetophenone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 1-hydroxycyclohexyl phenyl ketone, α, α-diethoxyacetophenone, 2-hydroxy-2 -Methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl Propan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl Acetophenone photopolymerization initiators such as lepropan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin Benzoin ether photopolymerization initiators such as isopropyl ether and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 2,4,6-trimethylbenzophenone Benzophenone photopolymerization initiators such as: 2-Isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, thioxanthates such as 1-chloro-4-propoxythioxanthone Photopolymerization initiator; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) Acylphosphine oxide photoinitiators such as phenylphosphine oxide; 1,2-octanedione, oxime ester systems such as 1- [4- (phenylthiophenyl)]-, 2- (O-benzoyloxime) Photopolymerization initiator; camphorquinone and the like can be mentioned.

  The radical photopolymerization initiator (ζ) can be used alone or in combination of two or more according to the desired performance. When the radical photopolymerization initiator (ζ) is blended, the blending ratio is preferably 10% by mass or less, based on the entire composition, from the viewpoint of obtaining sufficient curing and strength, and 0.1 to 3.0 mass. % Is more preferable.

(Other components (η))
Furthermore, in the photocurable adhesive composition that can be used in the present invention, other components different from the above (α1) to (ζ) components are arbitrarily blended within a range not impairing the effects of the present invention. Can do.
As one type belonging to such other components, there may be mentioned compounds having cationic polymerizability other than the epoxy compound (α1) and the oxetane compound (α2). Specific examples include, but are not limited to, an epoxy compound having one epoxy group in the molecule, and the like. Further, as another type belonging to the other component, other component (η) having no polymerizability can be exemplified. When the other component (η) having no polymerizability is blended, the blending ratio is preferably about 10% by mass or less based on the entire composition.

  Although it does not specifically limit as an example of the other component ((eta)) which does not have polymerizability, A photosensitizer is mentioned. By blending a photosensitizer, the reactivity is improved and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes.

  Specific photosensitizers are not particularly limited. For example, benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o -Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone; 2 -Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; Acridone derivatives such as N-methylacridone and N-butylacridone; Others, α, α-diethoxyacetophenone, benzyl, full Examples include olenone, xanthone, uranyl compound, halogen compound and the like.

  Among these, there is a compound corresponding to the above-mentioned photo radical polymerization initiator (ζ), but the photo sensitizer here is particularly one that functions as a sensitizer for the photo cationic polymerization initiator (β 1). It is not limited. These may be used alone or in combination of two or more.

  The photosensitizer is a cationically polymerizable monomer (including the above epoxy compound (α1) and oxetane compound (α2) in the photocurable adhesive composition that can be used in the present invention, and has the other cationic polymerization properties described above. It is preferable to contain in the range of 0.1-20 mass parts by making 100 mass parts the total amount of a compound including that when the compound is mix | blended.

  Moreover, a thermal cationic polymerization initiator can also be used as another component ((eta)) which does not have polymerizability. Examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium salt, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These initiators can be easily obtained as commercial products. For example, both of them are indicated by trade names, and ADEKA OPTON CP77 and ADEKA OPTON CP66 (manufactured by ADEKA, Inc.), CI-2639, CI- 2624 (manufactured by Nippon Soda Co., Ltd.), Sun-Aid SI-60L, Sun-Aid SI-80L, Sun-Aid SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.), and the like.

  Since polyols have the property of promoting cationic polymerization, they can also be used as other components (η) that do not have polymerizability. As the polyols, those having no acidic groups other than phenolic hydroxy groups are preferable. For example, polyol compounds having no functional groups other than hydroxy groups, polyester polyol compounds, polycaprolactone polyol compounds, polyol compounds having phenolic hydroxy groups. And polycarbonate polyol compounds.

Furthermore, as long as the effects of the present invention are not impaired, other components (η) having no polymerizability include silane coupling agents, ion trapping agents, antioxidants, light stabilizers, chain transfer agents, sensitizers, and tackifiers. An agent, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, a leveling agent, a dye, an organic solvent, and the like can also be blended.
In order to further improve the adhesion to the cellulose acylate film as another component (η) having no polymerizability, it is also effective to blend a thermoplastic resin. As the thermoplastic resin, those having a glass transition temperature of 70 ° C. or higher are preferable from the viewpoint of enhancing the durability of the polarizer, and particularly preferred examples include a methyl methacrylate polymer.

<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 5 to 30 μm, particularly preferably 10 to 20 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. The ethylene-modified polyvinyl alcohol is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature 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.

<Production method of polarizing plate>
The polarizing plate is a cellulose acylate containing a cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 and a Tg lowering agent on one surface of a polarizer using a photocurable adhesive. It can be manufactured by laminating rate films. During lamination, among both surfaces of the cellulose acylate film, r value satisfies the above 1.1, a surface d _A is detected, bonded to the polarizer. That is, of the two surfaces of the cellulose acylate film, the surface with the larger detection value of the Tg reducing agent by time-of-flight secondary ion mass spectrometry is used as the bonding surface with the polarizer.

  In addition, the cellulose acylate film which concerns on this invention may be used for the other surface of the polarizer which comprises a polarizing plate, and it is also preferable to paste another optical film. Examples of such other optical films include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, HC8UX, HAC, -RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

Hereinafter, an example of the manufacturing method of the polarizing plate using a photocurable adhesive agent is demonstrated.
The polarizing plate has the following photo-curing adhesive on at least one of the pretreatment step for easily adhering the surface of the cellulose acylate film to which the polarizer is adhered and the adhesive surface of the polarizer and the cellulose acylate film. Adhesive application process to be applied, a polarizer and a cellulose acylate film are bonded and bonded via an adhesive layer, and a polarizer and a cellulose acylate film are bonded via an adhesive layer It can manufacture by the manufacturing method including the hardening process which hardens an adhesive bond layer in a state.

(Pretreatment process)
In the pretreatment step, the surface of the cellulose acylate film that adheres to the polarizer is subjected to an easy adhesion treatment. When a cellulose acylate film is adhered to both surfaces of the polarizer, an easy adhesion treatment is performed on each cellulose acylate film. In the next adhesive application step, the surface subjected to the easy adhesion treatment is treated as a bonding surface with the polarizer, and therefore, among both surfaces of the cellulose acylate film, the r value satisfies 1.1 or more, d _A is The detected surface is subjected to an easy adhesion treatment.

(Adhesive application process)
In the adhesive application step, the photocurable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the cellulose acylate film. When the photocurable adhesive is applied directly to the surface of the polarizer or the cellulose acylate film, there is no particular limitation on the application method. For example, various 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 a photocurable adhesive between a polarizer and a cellulose acylate film, the method of pressurizing with a roller etc. and spreading it uniformly can also be utilized.

(Bonding process)
Thus, after apply | coating a photocurable adhesive agent, it uses for a bonding process. In this bonding step, for example, when a photocurable adhesive is applied to the surface of the polarizer in the previous application step, a cellulose acylate film is superimposed thereon. When a photocurable adhesive is applied to the surface of the cellulose acylate film in the previous application step, a polarizer is superimposed thereon. Moreover, when a photocurable adhesive agent is cast between a polarizer and a cellulose acylate film, a polarizer and a cellulose acylate film are piled up in that state. When a cellulose acylate film is bonded to both sides of a polarizer and a photocurable adhesive is used on both sides, the cellulose acylate film is superimposed on each side of the polarizer via a photocurable adhesive. Is done. Usually, in this state, both sides (when the cellulose acylate film is superimposed on one side of the polarizer, the polarizer side and the cellulose acylate film side are referred to. When the cellulose acylate film is superimposed on both sides of the polarizer, Means the cellulose acylate film side of both surfaces), and is pressed with a roller or the like. 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 process, an uncured photocurable adhesive is irradiated with active energy rays to cure the adhesive layer containing an epoxy compound or an oxetane compound, and the polarizer and cellulose layered via the photocurable adhesive Adhere to acylate film. When a cellulose acylate film is bonded to one side of the polarizer, the active energy ray may be irradiated from either the polarizer side or the cellulose acylate film side. Moreover, when bonding a cellulose acylate film on both surfaces of a polarizer, either cellulose acylate film is in a state in which the cellulose acylate film is superposed on both surfaces of the polarizer via a photocurable adhesive. It is advantageous to irradiate active energy rays from the side and simultaneously cure the photocurable adhesive on both sides. However, when a UV absorber is blended in one of the cellulose acylate films and the active energy ray is UV, the other cellulose acylate film side not blended with the UV absorber is usually used. Is irradiated with ultraviolet rays.

  Visible light, ultraviolet rays, X-rays, electron beams, and the like can be used as the active energy rays, but ultraviolet rays are generally preferably used because they are easy to handle and have a sufficient curing rate. The light source of the active energy ray is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less. An LED lamp or the like can be used.

The light irradiation intensity to the photocurable adhesive is determined for each target composition and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is UV. It is preferable to adjust so that it may become the range of 1-3000 mW / cm < ² > as -B (280-320 nm medium wavelength range ultraviolet-ray). If the irradiation intensity is in the range of 1 to 3,000 mW / cm ² , an appropriate reaction time is sufficient, and the yellow of the photo-curable adhesive due to heat radiated from the lamp and heat generated during polymerization of the photo-curable adhesive. Deformation and deterioration of the polarizer can be prevented.

The light irradiation time to the photocurable adhesive is controlled for each composition to be cured and is not particularly limited, but the integrated light amount represented by the product of the irradiation intensity and the irradiation time is 10 to 5000 mJ / cm. It is preferably set to be in the range of ² . If the integrated light quantity is in the range of 10 to 5000 mJ / cm ² , active species derived from the polymerization initiator are sufficiently generated, and the adhesive layer is sufficiently cured. In addition, an appropriate irradiation time is sufficient, which is suitable for improving productivity.

  When curing the photocurable adhesive by irradiating active energy rays, it is cured under conditions that do not deteriorate the various functions of the polarizing plate, such as the degree of polarization of the polarizer, the transmittance, the hue, and the transparency of the cellulose acylate film. It is preferable.

  In the polarizing plate obtained as described above, the thickness of the adhesive layer is not particularly limited, but is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and further preferably 5 μm or less.

<Liquid crystal display device>
The polarizing plate according to the present invention can be suitably used for a liquid crystal display device. The liquid crystal display device using the polarizing plate according to the present invention is excellent in visibility because a cellulose acylate film having an excellent optical compensation function is used. In addition, such a liquid crystal display device has excellent durability because of high adhesion between the polarizer and the cellulose acylate film.

The bonding between the surface of the polarizing plate on the cellulose acylate film side 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. A VA (MVA, PVA) type liquid crystal display device is preferable. By using the polarizing plate according to the present invention for these liquid crystal display devices, even with a 30-inch or larger screen liquid crystal display device, there are few environmental fluctuations and excellent visibility such as uneven coloring and front contrast. A liquid crystal display device can be obtained.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, “part” or “%” used in Examples represents “part by mass” or “% by mass” unless otherwise specified.

[Example 1]
<Preparation of Cellulose Acylate Film 101>
(Preparation of fine particle dispersion 1)
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to prepare a fine particle dispersion 1.

(Preparation of fine particle additive solution 1)
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. The masses of methylene chloride and fine particle dispersion 1 are as follows. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.
99 parts by mass of methylene chloride 5 parts by mass of fine particle dispersion 1

(Preparation of main dope solution)
A main dope solution having the following composition was prepared.
Methylene chloride 340 parts by mass Ethanol 64 parts by weight Cellulose acylate (cellulose acylate having an acetyl substitution degree of 2.45 and a weight average molecular weight Mw of 135,000, and a cellulose acylate having an acetyl substitution degree of 2.45 and a weight average molecular weight of Mw of 180000 are 6: 100 parts by mass Hydrolysis inhibitors (sugar ester compounds (a1), (a2), (a3), (a4) were mixed at a mass ratio of 1: 14: 35: 40 (a1: a2: a3: a4) mixture, average log P value = 8.7, Tg reduction ability = 2.1 ° C./part by mass) 8 parts by mass Particulate additive liquid 1 1 part by mass

  First, methylene chloride and ethanol having the above composition were added to a pressure dissolution tank. In a pressure dissolution tank containing this solvent, cellulose acylate having an acetyl substitution degree of 2.45 and a weight average molecular weight Mw of 135,000, and a cellulose acylate having an acetyl substitution degree of 2.45 and a weight average molecular weight of Mw of 180,000 were 6: 4. The cellulose acylate having the above composition mixed in a mass ratio was added while stirring. After heating and stirring, this was completely dissolved, and then Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. was used. The main dope solution was prepared by filtration using 244. The main dope solution was put into a sealed container and dissolved while stirring to prepare a dope solution.

(Preparation of cellulose acylate film)
Next, using an endless belt casting apparatus, the dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.
On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) cellulose acylate film was 88%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.
The peeled cellulose acylate film was stretched 1.15 times in the width direction using a tenter while applying heat at 160 ° C. The residual solvent amount at the start of stretching was 10%.
Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the conveyance tension was 100 N / m.
As described above, a cellulose acylate film 101 having a dry film thickness of 45 μm and a length of 2000 m was obtained.

<Production of Cellulose Acylate Films 102-118>
Cellulose acylate films 102 to 118 were produced in the same manner as the cellulose acylate film 101 except that the dope solution composition and production conditions were changed as shown in Table 1 below. In the production of the cellulose acylate film 101, the Tg reducing agent was not added. However, when the Tg reducing agent is added, the composition of the main dope solution includes the Tg reducing agent.

  Table 1 shows compounds of Tg lowering agents contained in the main dope liquid compositions of the cellulose acylate films 101 to 118, addition amounts, values of Tg lowering ability, compounds mixed as hydrolysis inhibitors, and mixtures of compounds. The ratio, the added amount, the average log P value, and the value of the residual solvent amount in the cellulose acylate film at the time of peeling are described.

<Evaluation>
For the cellulose acylate films 101 to 118 obtained above, the following measurement method was used to determine the r value, which is the ratio of the Tg reducing agent distribution on both surfaces, the s value, which is the ratio of the hydrolysis inhibitor distribution, and the arithmetic mean. The roughness Ra was measured. The measurement results are shown in Table 1 below. In Table 1, the Q1 surface represents the surface opposite to the surface that was in contact with the metal support during casting of the dope. The Q2 plane represents the plane that was in contact with the metal support during casting of the dope.

(Measurement method of r value and s value)
The detection value of the Tg reducing agent on each surface of the cellulose acylate films 101 to 118 was obtained using time-of-flight secondary ion mass spectrometry under the following measurement conditions.
Measuring device: 2100TRIFT2 (Phisical Electronics)
Measurement mode: Cooling measurement (temperature range -95 to -105 ° C)
Primary ion: Ga (15 kV)
Measurement area: 60 μm square Integration time: 2 minutes Reference ion m / Z in the case of Tg reducing agent (aromatic polyester (ar-14)): 119
Reference ion m / Z in the case of hydrolysis inhibitor (mixture of sugar ester compounds (a1), (a2), (a3), (a4)): 105
Among the detected values of Tg-lowering agent of the surface, as better the d _A, the smaller the d _B large, according to the above equation (1) to calculate the r value.
In addition, except for the cellulose acylate films 101 and 108 to which no Tg lowering agent is added, the cellulose acylate films 102 to 107 and 109 to 118 have a detected value of the Tg lowering agent on the Q2 surface than on the Q1 surface. Was big.

Under the same measurement conditions, the detection value of the hydrolysis inhibitor on each surface of the cellulose acylate films 101 to 118 was obtained using time-of-flight secondary ion mass spectrometry. Of the detected values of the hydrolysis inhibitor on each surface, the larger one was d _C and the smaller one was d _D , and the s value was calculated according to the above formula (2).

(Measurement method of arithmetic average roughness Ra)
In accordance with JIS B0601: 2001, the arithmetic average roughness Ra was measured with an optical interference surface roughness meter (RST / PLUS, manufactured by WYKO).

In Table 1, the aromatic polyester compound of the Tg reducing agent indicates the aromatic polyester compound (ar-5), (ar-14), (ar-16) or (PES-7) exemplified above. .
Hydrolysis inhibitor compound no. A1 to a4 in FIG. 4 represent sugar ester compounds (a1), (a2), (a3), and (a4). PETB represents pentaerythritol tetrabenzoate. The ratio of the compound of the hydrolysis inhibitor is the compound no. The mixing ratio of the compound shown by is shown.

[Example 2]
<Preparation of polarizing plates 201-221>
(Production of polarizer)
A 70 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. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 20 μm.

(Preparation of adhesive)
Each of the following components was mixed and then defoamed to prepare a photocurable adhesive liquid. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.

(Adhesive solution composition)
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 Tria Reelsulfonium 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)
Polarizing plates using the cellulose acylate films 101 to 118 were produced as follows.
First, a KC6UY (Konica Minolta Opto Co., Ltd.) film was prepared, and the surface was subjected to corona discharge treatment. The corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the adhesive solution prepared above was applied to the corona discharge treated surface of the film with a bar coater so that the film thickness after curing was about 3 μm to form an adhesive layer. The polyvinyl alcohol-iodine-type polarizer produced as mentioned above was bonded to the obtained adhesive layer.

Similarly, the surface of the cellulose acylate films 101 to 118 was subjected to corona discharge treatment. The conditions for the corona discharge treatment were a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the prepared adhesive liquid was applied to the corona discharge treated surfaces of the cellulose acylate films 101 to 118 with a bar coater so that the film thickness after curing was about 3 μm to form an adhesive layer. In that case, it bonded so that the slow axis of a cellulose acylate film and the absorption axis of a polarizer might become mutually orthogonal.
A polarizer polarizer having a KC6UY (Konica Minolta Opto Co., Ltd.) film bonded to one side is bonded to this adhesive layer, and cellulose acylate films 101 to 118 / polarizer / KC6UY (Konica Minolta) are bonded. An optical film laminate was obtained. From the cellulose acylate film 101-118 side of this laminate, using a UV irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems) so that the integrated light quantity becomes 750 mJ / cm ^2. The adhesive layer was cured by irradiating with ultraviolet rays.

In this manner, polarizing plates 201 to 221 in which a polarizer was sandwiched between two films were prepared using each of the cellulose acylate films 101 to 118.
Table 2 below shows which of the cellulose acylate films 101 to 118 used for the production of the respective polarizing plates 201 to 221 and whether the bonding surface with the polarizer is the Q1 surface or the Q2 surface. As shown.
That is, as shown in Table 2, the polarizing plates 201 to 218 have the Q2 surface of the cellulose acylate films 101 to 118 as the bonding surface with the polarizer, and the polarizing plates 219 to 221 are the cellulose acylate film 102, The Q1 surface of 104 and 109 was used as a bonding surface with a polarizer.

<Evaluation of polarizing plate>
About the obtained polarizing plates 201-221, the adhesiveness of a polarizer and a cellulose acylate film and the polarization degree of a polarizing plate were measured and evaluated with the following measuring methods. The evaluation results are shown in Table 2 below.

(Evaluation method for adhesion between polarizer and cellulose acylate film)
The polarizing plates 201-221 were allowed to stand for 500 hours under wet heat conditions of a temperature of 60 ° C. and 90% RH. Then, adhesiveness was evaluated by whether the polarizer which comprises the polarizing plates 201-221, and a cellulose acylate film can be peeled by hand.
The evaluation criteria are as follows.
○: Could not be peeled by hand.
X: It was able to peel by hand.

(Evaluation method of polarization degree of polarizing plate)
The degree of polarization of the polarizing plates 201 to 221 was measured using “V-7100” manufactured by JASCO Corporation.
Specifically, the parallel transmittance (H0) and orthogonal transmittance (H90) of the polarizing plate are measured, and the formula: degree of polarization (%) = {(H0−H90) / (H0 + H90)} ^1/2 × 100 The degree of polarization was calculated. Here, the parallel transmittance (H0) is a transmittance value of a parallel laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are parallel to each other. On the other hand, the orthogonal transmittance (H90) is a transmittance value of an orthogonal laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are orthogonal to each other. These transmittances are Y values obtained by correcting the visibility using a two-degree field of view (C light source) of JIS Z 8701 (1982 edition).
The evaluation criteria for the degree of polarization are as follows.
○: Polarization degree is 99.990 or more Δ: Polarization degree is 99.980 or more and less than 99.990 ×: Polarization degree is less than 99.980

As a result of the evaluation, all of the polarizing plates according to the present invention are excellent in adhesiveness with the polarizer, and also the degree of polarization of the polarizing plate is lowered due to the axial deviation at the time of bonding with the polarizer. It was shown that it can be suppressed.
On the other hand, all the polarizing plates using the cellulose acylate film of the comparative example are inferior in adhesion to the polarizer, and the decrease in the degree of polarization of the polarizing plate cannot be suppressed at a satisfactory level.

  It can be used in the field of liquid crystal display technology, and can be applied to polarizing plates and liquid crystal display devices using cellulose acylate.

Claims (7)

A cellulose acylate film containing a cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5 and a glass transition temperature lowering agent is formed on one of the polarizers using a photocurable adhesive. A polarizing plate bonded to a surface,
The detected value of the glass transition temperature reducing agent on the bonding surface of the cellulose acylate film, detected using time-of-flight secondary ion mass spectrometry (TOF-SIMS), is d _A , and the detected value of the other surface The polarizing plate is characterized in that the r value represented by the following formula (1) is 1.1 or more, where d is _B.
Formula (1) r = d _A / d _B   The polarizing plate according to claim 1, wherein the cellulose acylate is diacetyl cellulose having an acyl group substitution degree within a range of 2.0 to 2.5.   The polarizing plate according to claim 1 or 2, wherein the glass transition temperature lowering ability of the glass transition temperature lowering agent is 3.5 ° C / part by mass or more. The cellulose acylate film further comprises a hydrolysis inhibitor,
The polarizing plate according to claim 1, wherein an average log P value of the hydrolysis inhibitor is 7.5 or more.   The arithmetic average roughness of the said bonding surface is larger than the other surface, The polarizing plate as described in any one of Claims 1-4 characterized by the above-mentioned.   The polarizing plate according to any one of claims 1 to 5, wherein the polarizing plate has a polarization degree of 99.99% or more.   A liquid crystal display device comprising the polarizing plate according to claim 1.