TW201736878A - Polarizing plate, method for producing polarizing plate and liquid crystal display device - Google Patents

Abstract

The objective of the present invention is to provide: a polarizing plate which has improved durability and production efficiency; a method for producing this polarizing plate; and a liquid crystal display device which is provided with this polarizing plate. A polarizing plate according to the present invention is configured of a first protection film, a polarizer and a second protection film arranged in this order, and is characterized in that: the first protection film is a polyester film that has in-plane super birefringence and a light transmittance of 50% or more at 380 nm; the second protection film is a light-transmitting film that has a light transmittance of less than 50% at 380 nm; the in-plane retardation Ro (nm) of the second protection film as defined by formula (i) satisfies the condition defined by formula (iii); and the retardation Rt (nm) in the film thickness direction of the second protection film as defined by formula (ii) satisfies the condition defined by formula (iv). (i) Ro = (nx - ny) * d (ii) Rt = ((nx + ny)/2 - nz) * d (iii) 40 ≤ Ro ≤ 300 (iv) 100 ≤ Rt ≤ 400.

Description

Polarizing plate, manufacturing method of polarizing plate and liquid crystal display device

The present invention relates to a polarizing plate, a method of manufacturing the polarizing plate, and a liquid crystal display device. More specifically, the present invention relates to a polarizing plate having improved durability and production efficiency, a method for producing the same, and a liquid crystal display device including the same.

In recent years, display devices such as liquid crystal display devices (abbreviation: LCD) and organic electroluminescence display devices (abbreviation: OLED) have been progressing toward thinning. Along with this, the requirements for thinning of the polarizing plate included in the display device are increased.

In the polarizing plate, a protective film for protecting the polarizing mirror or the polarizing plate itself is usually provided. However, as a protective film on the visual recognition (observation) side of the display device, a polarizing plate using a polyester film is known (for example, refer to the patent document) 1).

In the past, as a polyester film used as a protective film on the visual recognition side, one of the protective functions requires a high ultraviolet absorbing ability.

In order to impart ultraviolet absorbing ability to the polyester film produced by the melt casting method, a method of adding an ultraviolet absorber to a film or a method of providing an ultraviolet absorbing layer or the like is known.

However, in the case where the ultraviolet absorber is added to the polyester film, the phenomenon that the ultraviolet absorber oozes out of the surface occurs, so-called "bleeding appearance", and as a result, in the film process or the polarizing plate process, due to the ultraviolet absorber oozing out This causes a problem of process contamination for rolls and the like, which causes a problem of a decrease in yield. Therefore, there has been proposed a method in which a film is laminated to suppress bleeding. However, the effect of the high quality level of the optical film used on the surface side of the display device is insufficient, and it is required to prevent the yield from being lowered. The development of manufacturing methods that maintain high productivity.

Further, when the ultraviolet absorbing layer is provided as another layer or when a hard coat layer is provided as a hard coat layer, a relatively large amount of the ultraviolet ray absorbing agent is contained in the layer of the film, and bleed out or the process is likely to occur in the same manner as described above. Contamination or as its yield decreases, is the result of reduced production efficiency.

In other words, when thinning the glass plate of the liquid crystal cell used in the liquid crystal display device or thinning the polarizer, it is used as a visual recognition side (observation side) in a high-temperature, high-humidity environment, particularly under a forced deterioration test condition. The polyester film containing the ultraviolet absorber used for the protective film is deteriorated in planarity, or process contamination due to bleeding during production of the ultraviolet absorber as described above, and productivity (yield) is lowered. The problem that it is easy to become large can be understood by review by the inventors.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5167814

The present invention has been made in view of the above problems, and a problem thereof is to provide a polarizing plate which is improved in durability and production efficiency (benefit ratio), a method for producing the same, and a liquid crystal display device including the same.

The inventors of the present invention have conducted a review of the above-mentioned problems, and as a result, it has been found that a polarizing plate having improved durability and production efficiency (benefit ratio) can be obtained from the visual recognition side as the first. The first protective film is a polyester film having a super-birefringence in the plane and a light transmittance of 380 nm of 50% or more, and the second protective film is composed of a protective film, a polarizing film, and a second protective film. A light-transmitting film having a light transmittance of less than 50% at 380 nm, and the second protective film is applicable to a light-transmitting film of a vertical alignment type (VA type) liquid crystal display device having a specific hysteresis value.

That is, the above problems of the present invention are solved by the following means.

A polarizing plate which is a polarizing plate which is formed by a first protective film, a polarizing mirror, and a second protective film from a visual recognition side, wherein the first protective film has an in-plane super a polyester film having a birefringence and a light transmittance of 380 nm of 50% or more, wherein the second protective film is a light-transmitting film having a light transmittance of less than 50% at 380 nm, and the second protective film is The hysteresis value Ro(nm) in the in-plane of the film defined by the following formula (i) satisfies the condition defined by the following formula (iii), and the hysteresis value Rt (nm) in the film thickness direction defined by the following formula (ii) It satisfies the conditions specified by the following formula (iv); (i) Ro = (n _{x -} n _y ) × d

(ii) Rt=((n _x +n _y )/2-n _z )×d

(iii) 40≦Ro≦300

(iv) 100≦Rt≦400

[wherein, the refractive index of the slow phase axis in the plane of the n _x film, the refractive index of the n _y film in the direction perpendicular to the direction of the slow axis; n _z is the refractive index perpendicular to the direction of the film face ;d system thickness (nm)].

2. The polarizing plate according to Item 1, wherein the second protective film contains a cellulose resin.

3. The polarizing plate of claim 1, wherein the second protective film contains a cycloolefin resin.

4. The polarizing plate according to any one of claims 1 to 3, wherein the second protective film contains at least one ester selected from the group consisting of a sugar ester, a polyester compound, and a polyol ester.

5. The polarizing plate according to any one of claims 1 to 4, wherein the second protective film contains at least one ultraviolet absorber selected from the group consisting of a benzotriazole-based compound and a triazine-based compound.

The polarizing plate according to any one of claims 1 to 5, wherein the first protective film has an ultraviolet curable resin layer.

7. A method of manufacturing a polarizing plate, which is manufactured as claimed The method for producing a polarizing plate for a polarizing plate according to any one of 1 to 6, wherein the second protective layer having a light transmittance of less than 50% at a light transmittance of 380 nm is formed by a melt casting method. The film is formed into a film.

A method of producing a polarizing plate, which is a method for producing a polarizing plate according to any one of claims 1 to 6, characterized in that the light having a wavelength of 380 nm is transmitted by a solution casting method. The second protective film having a light transmittance of less than 50% was formed into a film.

A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 6 on the surface of the liquid crystal cell (front side).

10. A liquid crystal display device comprising: a polarizing plate according to any one of claims 1 to 6 on each of a surface of a liquid crystal cell (front side) and a non-visual side (rear side); .

11. The liquid crystal display device of claim 9 or 10, wherein the glass substrate of the liquid crystal cell has a thickness in the range of 0.3 to 0.7 mm.

According to the above-described means of the present invention, it is possible to provide a polarizing plate having improved durability and productivity (yield), a method for producing the same, and a liquid crystal display device including the same.

The above problems can be solved by the configuration defined by the present invention, and the following reasons are presumed.

As described above, as a structure of a polarizing plate, a polyester film used as the first protective film, for example, polyethylene terephthalate (hereinafter referred to as "PET") film, which requires high ultraviolet absorption as a protective function, and a UV absorber.

However, a method of adding an ultraviolet absorber to the film itself or a method of separately providing an ultraviolet absorbing layer in order to impart ultraviolet absorbing property to the film of the polyester film produced by the melt casting method is known. However, if an ultraviolet absorber is added to the polyester film itself, process contamination occurs due to occurrence of bleeding or the like, causing contamination in the film process or the process of the polarizing plate, which causes a problem of a decrease in yield. In order to suppress the occurrence of bleed, there is a proposal to form a laminated structure to suppress bleed. However, the optical film used for the surface of the liquid crystal display device is retrogressed in comparison with the recent increase in quality requirements such as thin film formation. In the direction, and as the formation of new layers increases in man-hours, the yield is increasingly reduced, which is a major factor in reducing production efficiency. Further, when a constituent layer containing the ultraviolet absorbing layer is newly provided or when the ultraviolet absorbing property of the hard coat layer is imparted, the layer of the film contains a relatively large amount of the ultraviolet absorbing agent, and even if it is constituted as described above, Process contamination or reduced yield due to it reduces production efficiency.

In the present invention, when a polyester film is used as the protective film (first protective film) on the visual recognition side, the amount of the ultraviolet absorber added to the polyester film is reduced, or preferably, the ultraviolet film is not contained in the polyester film. In the form of the absorbent, the light transmittance at 380 nm is set to 50% or more, and the decrease in yield due to the occurrence of bleeding due to the large amount of the ultraviolet absorber added can be prevented. With this configuration, although the light resistance of the polarizer disposed thereunder is feared, it is found that the influence is unexpectedly small. The other side In the other protective film (second protective film), a UV absorber that imparts ultraviolet absorbing properties is added, and various functional compounds are added, and the light transmittance at 380 nm is less than 50%. The liquid crystal cell constituting the liquid crystal display device achieves necessary ultraviolet durability (ultraviolet light shielding effect), and the second protective film is a retardation value of the film in the surface of the second protective film defined by the above formula (i) Ro(nm) satisfies the condition specified by the above formula (iii), and the hysteresis value Rt (nm) of the film thickness direction defined by the formula (ii) satisfies the condition specified by the above formula (iv), and provides excellent yield. The polarizing plate can be applied to a vertical alignment type (VA type) liquid crystal display device, which can reduce the manufacturing cost of the display device.

In the past, the thinning of the glass substrate for the liquid crystal cell has been made higher in quality of the polarizing plate, and as a result, the yield is lowered. However, the structure of the polarizing plate of the present invention can be remarkably improved.

1‧‧‧Solution kettle

3, 6, 12, 15 ‧ ‧ filters

4, 13‧‧ ‧ storage kettle

5, 14‧‧‧ liquid pump

8, 16‧‧‧ catheter

10‧‧‧UV absorber feed kettle

20‧‧ ‧ Confluence tube

21‧‧‧ Mixer

30‧‧‧ Pressing die

31‧‧‧Metal support

32‧‧‧ mesh

33‧‧‧ peeling position

34‧‧‧ tenter extension

35‧‧‧Drying device

41‧‧‧ Feeding kettle

42‧‧‧Storage kettle

43‧‧‧ pump

44‧‧‧Filter

51‧‧‧Polar plate

52, 102A, 102B‧‧‧ first protective film

53, 104A, 104B‧‧‧ polarizer

54, 105A, 105B‧‧‧ 2nd protective film

55‧‧‧UV hardened resin layer

100‧‧‧Liquid crystal display device

101A, 101B‧‧‧ polarizing plate

101C‧‧‧ liquid crystal cell

103A, 103B, 103C, 103D‧‧‧ UV curing adhesive

106‧‧‧Adhesive layer

107‧‧‧Liquid layer

108A, 108B‧‧‧ glass substrate

400‧‧‧Manufacture of devices

410, 420‧‧‧cycloolefin film

430‧‧‧ film reel

510‧‧‧die

516‧‧‧ lips

520‧‧‧ casting rolls

521‧‧‧ outer perimeter

531, 532‧‧‧Electrostatic pinning device

540‧‧‧ peeling roller

550‧‧‧Edge trimming device

551, 552‧‧‧ trimming knife

Fig. 1A is a schematic cross-sectional view showing an example of a configuration of a polarizing plate of the present invention.

Fig. 1B is a schematic cross-sectional view showing another example of the configuration of a polarizing plate of the present invention.

Fig. 2 is a view schematically showing an example of a dope preparation step, a casting step, and a drying step which are applicable to the solution casting method of the present invention.

Fig. 3 is a view schematically showing an example of a dope preparation step, a casting step, and a drying step which can be applied to the melt casting method of the present invention.

Fig. 4 is a model diagram showing an example of the configuration of a liquid crystal display device of the present invention.

[Formation of the Invention]

The polarizing plate of the present invention is a polarizing plate comprising a first protective film, a polarizing mirror, and a second protective film from the visual recognition side, wherein the first protective film has super-birefringence in the plane. And a polyester film having a light transmittance of 380 nm of 50% or more, wherein the second protective film is a light transmissive film having a light transmittance of less than 50% at 380 nm, and the second protective film is as follows The hysteresis value Ro(nm) in the in-plane of the film defined by the formula (i) satisfies the condition defined by the following formula (iii), and the hysteresis value Rt (nm) in the film thickness direction defined by the following formula (ii) is satisfied. The condition specified by the following formula (iv); (i) Ro = (n _{x -} n _y ) × d

(ii) Rt=((n _x +n _y )/2-n _z )×d

(iii) 40≦Ro≦300

(iv) 100≦Rt≦400

In the above formulas (i) and (ii), the refractive index in the direction of the slow axis in the plane of the n _x film, the refractive index in the direction perpendicular to the direction of the slow axis in the plane of the n _y film; n _z is perpendicular to The refractive index of the direction of the film surface; the thickness (nm) of the d-type film.

This feature is common or corresponds to the invention of each request item. feature.

In the embodiment of the present invention, the cellulose resin or the cycloolefin resin is contained as the second protective film, and the ultraviolet absorber or the like is contained in a stable manner. It is preferable to form a second protective film excellent in durability.

In addition, the second protective film contains at least one ester selected from the group consisting of a sugar ester, a polyester compound, and a polyol ester, and is preferable from the viewpoint of imparting flexibility to the second protective film.

In addition, it is preferable that the second protective film contains at least one ultraviolet absorber selected from the benzotriazole-based compound and the triazine-based compound, and it is preferable in that it can exhibit the durability of the effect of the present invention.

In order to impart the necessary ultraviolet absorbing property to the second protective film, it is necessary to increase the content of the ultraviolet absorbing agent or to increase the film thickness of the entire film. However, if the amount of the ultraviolet absorbing agent is increased, there is a problem that bleed out and phase separate to increase the haze. . Further, if the film thickness is increased, the hysteresis value is increased, so that the problem is coexisting. In the present invention, when the second protective film contains a sugar ester or a polyester, it is difficult to increase the hysteresis value even if the ultraviolet absorber is contained. Therefore, it is possible to provide a film which satisfies the ultraviolet absorbing property and the desired hysteresis value and has a small film thickness. As the ultraviolet absorber, a benzotriazole-based compound is preferable, in particular, by using "2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl) -4-(1,1,3,3-tetramethylbutyl)phenol is a UV absorber that provides a second protective film that satisfies the desired UV absorbability and hysteresis value and has a thin film thickness. Good to use.

Further, the first protective film further has an ultraviolet curing resin The layer is preferably at a point where excellent damage resistance can be obtained.

The second protective film of the present invention is preferably formed by a melt casting method or a solution casting method.

Among them, the solution casting method is less restrictive when containing a plurality of different additives at the same time, and as a result, it is more preferable to provide a manufacturing method capable of simultaneously solving the problem of plural.

Further, the polarizing plate of the present invention is provided on each of the surface on the visual recognition side (front side) of the liquid crystal cell or on the surface on the visual recognition side (front side) of the liquid crystal cell and the non-visual identification side (rear side). The liquid crystal display device is characterized. In addition, it is preferable to set the thickness of the glass substrate used for the liquid crystal cell to a range of 0.3 to 0.7 mm in order to obtain a thinner liquid crystal display device.

Hereinafter, the present invention and its constituent elements and aspects for carrying out the invention will be described in detail. In addition, the "~" shown in the present invention is used in the meaning of including the numerical values described before and after the lower limit and the upper limit. In addition, the numerals described in parentheses after the constituent elements in the description of the respective drawings indicate the symbols described in the respective drawings.

Polarizer

1A and 1B are schematic cross-sectional views showing an example of a configuration of a polarizing plate of the present invention.

The polarizing plate (51) of the present invention is composed of a first protective film (52), a polarizing mirror (53), and a second protective film (54) from the visual recognition side as shown in Fig. 1A. The first protective film (52) is attached to the surface. a polyester film having super-birefringence and having a light transmittance of 380 nm of 50% or more, the second protective film being a light-transmitting film having a light transmittance of less than 50% at 380 nm, and the second protection The hysteresis value Ro(nm) in the in-plane of the film defined by the above formula (i) satisfies the condition specified by the above formula (iii), and the hysteresis value Rt (nm) of the film thickness direction defined by the formula (ii) is as described above. ) satisfying the conditions specified in the above formula (iv).

Further, as another configuration, as shown in FIG. 1B, in addition to the configuration shown in FIG. 1A, the ultraviolet curable resin layer (55) is further provided on the visual recognition surface side of the first protective film (52). This is also one of the better aspects.

Hereinafter, the details of each component of the polarizing plate of the present invention will be described.

[First protective film]

The first protective film constituting the polarizing plate of the present invention is characterized by having a super-birefringence in the plane and a polyester film having a light transmittance of 380 nm of 50% or more (hereinafter also referred to as a polyester film).

The present invention has super-birefringence in the plane, which means that the hysteresis value Ro in the in-plane direction is in the range of 3,000 to 30,000 nm. The hysteresis value Ro of the in-plane direction as referred to herein is defined by the following formula (i).

Formula (i)Ro=(n _x -n _y )×d

Further, the hysteresis Rt in the thickness direction of the film film to be described later is defined by the following formula (ii).

Formula (ii) Rt=((n _x +n _y )/2-n _z )×d

In the formulas (i) and (ii), the refractive index in the direction of the slow axis in the plane of the n _x film; the refractive index in the direction perpendicular to the direction of the slow axis in the plane of the n _y film; n _z is perpendicular to the film The refractive index of the direction of the face; the thickness (nm) of the d-type film.

In the present invention, the direction in which the forward speed of light is fast (phase advancement) is referred to as the "phase advance axis" of the phase subphase, and the slow (phase slow) direction is referred to as the "late phase axis". The phase axis and the slow phase axis are collectively referred to as the "spindle" of birefringence.

The hysteresis value Ro in the in-plane direction and the hysteresis value Rt in the film thickness direction of the film can be obtained by using an automatic birefringence meter Axo Scan Mueller Matrix Polarimeter (manufactured by AXO METRIX Co., Ltd.) at 23 ° C ‧55% RH In the environment, the three-dimensional refractive index measurement at a wavelength of 590 nm was performed, and the obtained refractive indices n _x , n _{x ,} and n _z were calculated.

Further, in the first protective film, a polyester film having a light transmittance of 380 nm of 50% or more is regarded as one of the characteristics.

The light transmittance of the polyester film of the present invention at a wavelength of 380 nm can be determined, for example, by using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, UV-Vis NIR spectrophotometer, product name: V7100). It is characterized by a light transmittance of 5% at 380 nm or more, but It is preferably in the range of 60 to 95%, more preferably in the range of 70 to 95%, and particularly preferably in the range of 80 to 95%.

In the first protective film of the present invention, the method of making the light transmittance at 380 nm 50% or more is effective because the additive having light absorption at 380 nm is not added as much as possible in the film, and is not particularly added. The composition of the ultraviolet absorber having a strong absorption in the ultraviolet region is preferred.

The polyester film of the present invention, more specifically, the retardation value Ro of the stretched polyester film is preferably in the range of 3,000 to 30,000 nm from the viewpoint of exhibiting super-birefringence. The lower limit of the hysteresis value of the stretched polyester film is preferably 4,500 nm or more, more preferably 6,000 nm or more, particularly preferably 8,000 nm or more, and particularly preferably 10,000 nm or more. On the other hand, the upper limit of the hysteresis value Ro of the stretched polyester film is 30000 nm, but even if a film having a hysteresis value Ro or more is used, substantially no improvement in visibility is obtained, and since there is hysteresis Since the height of the film is increased, the thickness of the film is also increased. Therefore, from the viewpoint of not failing to meet the requirements for thinning and the workability as an industrial material, it is preferably set at 30,000 nm or less.

Further, as another viewpoint, by providing the first protective film having birefringence between the two orthogonal polarizing plates, the linearly polarized light emitted from the polarizing plate is disturbed when passing through the first protective film. The transmitted light is in the plane of the first protective film, and the hysteresis value Ro of the product of super birefringence and thickness shows a unique interference color. Therefore, by the first protective film, the light of the transmitted light of the interference color is displayed within a range of the specific hysteresis value Ro. The envelope shape of the spectrum is approximated to the luminescence spectrum of the source.

In order to achieve the above effects, the first protective film used in the present invention preferably has a hysteresis value Ro of 3,000 to 30,000 nm. When the hysteresis value Ro is 3000 nm or more, since a strong interference color is exhibited when the screen is observed by a polarizing plate such as sunglasses, the envelope shape is similar to the light emission spectrum of the light source, and good visibility can be ensured. A preferred lower hysteresis value is 4500 nm, a more preferred lower limit is 6000 nm, a more preferred lower limit is 8000 nm, and a particularly preferred lower limit is 10000 nm.

In addition, when the ultraviolet absorber is contained in the polyester film as the first protective film, the birefringence is lowered, and in order to maintain the super birefringence, it is necessary to increase the stretching ratio, the extension temperature, and the like in the production of the polyester film. However, if such a means is employed, there is a problem that the haze is increased to lower the contrast of the display device. In addition, there is a method of increasing the film thickness of the polyester film to satisfy the birefringence value. However, as the display device is increased in size and required to be lighter and thinner, the quality and thickness are increased, and the polyester film is changed. It is thick, and it is also a cause of manufacturing troubles or malfunctions caused by a decrease in operability when manufacturing a polarizing plate or a display device. In order to solve the above problems, it is not necessary to contain an ultraviolet absorber in the polyester film as the first protective film by the configuration defined in the present invention, and such a problem can be prevented.

The ratio of the retardation value Ro in the in-plane direction of the stretched polyester film to the retardation value Rt in the thickness direction (Ro/Rt) is preferably 0.2 or more, more preferably 0.5 or more, and particularly preferably 0.6 or more.

The maximum value of Ro/Rt is 2.0 (ie, complete uniaxial symmetry) Thin film), but with the nearly complete uniaxial symmetry film, the mechanical strength in the direction orthogonal to the alignment direction tends to decrease. Therefore, the upper limit of the Ro/Rt of the polyester film is preferably 1.2 or less, more preferably 1.0 or less.

The polyester of the raw material resin of the stretched polyester film is excellent in transparency and excellent in thermal properties and mechanical properties, and can be easily controlled to have a desired hysteresis value by stretching processing. Among the polyesters, polyethylene terephthalate (abbreviation: PET) or polyethylene naphthalate (abbreviation: PEN) is preferred. Polyester typified by polyethylene terephthalate and polyethylene naphthalate has a large intrinsic birefringence, and it is preferable to obtain a large hysteresis value relatively easily even if the thickness of the film is thin. In particular, polyethylene naphthalate is preferred because it has a large intrinsic birefringence among the polyesters, and when it is desired to particularly increase the hysteresis value, or to maintain a high hysteresis value while thinning the film thickness. .

(Method for producing an extended polyester film)

Hereinafter, an outline of a method for producing an extended polyester film will be described.

The polyester film can be obtained by condensing any dicarboxylic acid with a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 1,4-naphthalenedicarboxylic acid. 1,5-naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylphosphonium carboxylic acid, stilbene dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1 , 3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3 ,3-diethyl succinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipate, trimethyl adipate, pimelic acid, sebacic acid Dimer acid, bismuth Acid, suberic acid, dodecane dicarboxylic acid, and the like.

Examples of the diol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and tetramethylene. Glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, bis (4) -Hydroxyphenyl)anthracene and the like.

One type or two or more types of the dicarboxylic acid component and the diol component which are constituting the polyester film can be used. Specific examples of the polyester resin constituting the polyester film include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. And the like, preferably polyethylene terephthalate and polyethylene naphthalate, more preferably polyethylene terephthalate. The polyester resin may contain other copolymerization components as needed, and the ratio of the copolymerization component is preferably 3.0 mol% or less, more preferably 2.0 mol% or less, and particularly preferably 1.5, from the viewpoint of mechanical strength. Mole% or less. These resins are excellent in transparency and excellent in heat and mechanical properties. Moreover, these resins can easily control the hysteresis value by stretching processing.

The polyester film can be obtained in accordance with a general production method. Specifically, a polyester resin is melted, and the unaligned polyester formed by extrusion into a sheet shape is formed at a temperature equal to or higher than the glass transition temperature, and is stretched in the longitudinal direction by the difference in speed of the rolls. The machine is extended in the lateral direction, and a melt casting method of the stretched polyester film or the like is produced by applying heat treatment and optionally relaxation treatment. The extended polyester film may be a uniaxially stretched film or a biaxially stretched film.

The production conditions for obtaining the polyester film can be appropriately set in accordance with a well-known method. For example, the longitudinal stretching temperature and the lateral stretching temperature are usually 80 to 130 ° C, preferably 90 to 120 ° C. The longitudinal stretching ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times. Further, the lateral stretching ratio is usually 2.5 to 6.0 times, preferably 3.0 to 5.5 times.

Specific means for controlling the hysteresis value to a specific range include means for appropriately setting the stretching ratio, the stretching temperature, and the thickness of the film. For example, the higher the difference in stretch ratio between the longitudinal extension and the lateral extension, the lower the extension temperature, and the thicker the thickness of the film, the easier it is to obtain a high hysteresis value. Conversely, the lower the difference in stretch ratio between the longitudinal extension and the transverse extension, the higher the extension temperature, and the thinner the thickness of the film, the easier it is to obtain a low hysteresis value. Further, the higher the extension temperature, the lower the total stretching ratio, and the easier it is to obtain a film having a lower ratio of retardation value to thickness direction retardation (Ro/Rt). Conversely, the lower the extension temperature, the higher the total stretching ratio, and the higher the ratio of the hysteresis value to the retardation value in the thickness direction (Ro/Rt). Further, the heat treatment temperature is generally preferably in the range of from 140 to 240 ° C, more preferably in the range of from 170 to 240 ° C.

The temperature of the relaxation treatment is usually in the range of 100 to 230 ° C, preferably in the range of 110 to 210 ° C, more preferably in the range of 120 to 180 ° C. Further, the amount of slack is usually in the range of 0.1 to 20%, preferably in the range of 1 to 10%, more preferably in the range of 2 to 5%. The temperature and the amount of relaxation of the relaxation treatment are preferably such that the amount of slack and the temperature during the relaxation treatment are set such that the heat shrinkage ratio of the polyester film after the relaxation treatment is 2% or less at 150 °C.

Also, in the uniaxial extension and biaxial extension treatment, After the transverse stretching, the skew of the alignment main shaft represented by the arching, which is offset by the alignment angle in the in-plane direction, may be subjected to heat treatment or elongation treatment. The maximum value of the skew due to the direction of extension of the alignment main axis due to the arching is preferably within 30, more preferably within 15, and even more preferably within 8°. When the maximum value of the skew of the alignment main shaft exceeds 30°, when the polarizing plate is formed in the subsequent steps and is singulated, unevenness in optical characteristics may occur between the individual sheets. The so-called alignment main axis herein refers to the molecular alignment direction at any point on the extended polyester film. Further, the skew with respect to the extending direction of the alignment main axis means the angular difference between the alignment main axis and the extending direction. In addition, the maximum value means the maximum value of the value in the direction perpendicular to the longitudinal direction. For example, the alignment spindle can be measured by using a retardation film ‧ an optical material inspection device RETS (manufactured by Otsuka Electronics Co., Ltd.) or a molecular alignment meter MOA (manufactured by Oji Scientific Instruments Co., Ltd.).

In order to suppress the variation of the hysteresis value of the polyester film, the thickness unevenness of the film is preferably small. When the longitudinal stretching ratio is lowered in order to establish the hysteresis value difference, the value of the vertical thickness unevenness (hereinafter also referred to as "thickness unevenness") may become high. Since the value of the longitudinal thickness unevenness is a region which is extremely high in a certain range of the stretching ratio, it is preferable to set the film forming conditions outside such a range.

The thickness unevenness of the stretched polyester film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and particularly preferably 3.0% or less. The thickness unevenness of the film can be measured by any means. For example, a continuous tape-like sample (length 3 m) is taken in the direction of film transport, using commercially available The measuring machine, for example, "Electronic Micrometer Millitron 1240" manufactured by SEIKO-EM, measures the thickness of 100 points at a pitch of 1.0 cm, and obtains the maximum value (dmax), the minimum value (dmin), and the average value (d) of the thickness. The thickness unevenness (%) was calculated by the following formula.

Uneven thickness (%) = ((dma-dmin) / d) × 100

The thickness of the stretched polyester film is arbitrary, and can be suitably set, for example, in the range of 15 to 300 μm, preferably in the range of 30 to 200 μm, and particularly in the range of 60 to 80 μm, both filming and good vision can be achieved. The point of view of identification is more appropriate.

On at least one side of the stretched polyester film, various functional layers may also be provided. As such a functional layer, for example, a hard coat layer (also referred to as an ultraviolet curable resin layer), an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, an antireflection antiglare layer, and an antistatic layer can be used. One or more of the group consisting of a layer, a polysiloxane layer, an adhesive layer, an antifouling layer, a fingerprint-resistant layer, a water-repellent layer, and a blue-cut layer. In the present invention, the side of the visible surface of the stretched polyester film as the first protective film preferably has an ultraviolet curable resin layer as shown in FIG. 1B. Further, by providing an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer, it is also expected to further improve the effect of color unevenness when viewed from an oblique direction.

When various functional layers are provided, it is preferred to provide an easy-adhesion layer on the surface of the stretched polyester film. At that time, from the viewpoint of suppressing interference due to reflected light, it is preferable to adjust the refractive index of the easily-adhesive layer so as to be in the vicinity of the multiplication and average of the refractive index of the functional layer and the refractive index of the alignment film. The adjustment of the refractive index of the easy-adhesion layer can be carried out by a well-known method, for example, by adjusting titanium or zirconium, a metal species thereof in the binder resin. The coating liquid for forming the easily-adhesive layer is preferably an aqueous coating liquid containing at least one of a water-soluble or water-dispersible copolymerized polyester resin, an acrylic resin, and a polyurethane resin. Examples of the coating liquids include, for example, Japanese Patent Publication No. Hei. 6-81714, Japanese Patent No. 3200929, Japanese Patent No. 3632204, Japanese Patent No. 4547644, and Japanese Patent No. 4778971 Water-soluble or water disclosed in Japanese Laid-Open Patent Publication No. 3,567,927, Japanese Patent No. 3,589,232, Japanese Patent No. 3,589,233, Japanese Patent No. 3,900,191, Japanese Patent No. 4,150,982, and the like. A dispersible copolymerized polyester resin solution, an acrylic resin solution, a polyurethane resin solution, or the like.

(UV curable resin layer)

In the present invention, the first protective film preferably has a configuration of an ultraviolet curable resin layer.

As illustrated in FIG. 1B, it is preferable that the polarizing plate (51) having the first protective film (52), the polarizing mirror (53), and the second protective film (54) is further provided by the first protective film (52). The upper side (the side of the visual recognition surface) is further provided with a structure of an ultraviolet curable resin layer (55).

The details of the ultraviolet curable resin layer (hereinafter also referred to as "hard coat layer") of the present invention will be described.

Hard coating imparts hard coatability to the first protection of the present invention The layer for the surface of the film is, for example, a layer formed by using a composition for forming a hard coat layer containing an ultraviolet curable resin and a photopolymerization initiator to form a coating film, and then curing the ultraviolet curable resin by irradiation of ultraviolet rays.

The ultraviolet curable resin to be used in the present invention is not particularly limited as long as it is a resin component having a property of being cured by ultraviolet rays, and examples of the resin material include an acrylate-based compound having a functional group. A compound having 1 or more unsaturated bonds. Examples of the compound having one unsaturated bond include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Examples of the compound having two or more unsaturated bonds include polymethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, and diethylene glycol di(meth)acrylate. , pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, 1,6-hexane diol di (methyl) An acrylate, a neopentyl glycol di(meth)acrylate, or the like, and a polyfunctional compound modified with ethylene oxide (EO) or the like, or a polyfunctional compound or a (meth) acrylate or the like. A reaction product (for example, a poly(meth)acrylate of a polyhydric alcohol) or the like. In addition, "(meth)acrylate" as used in the present invention means methacrylate and acrylate.

In addition to the above compounds, a relatively low molecular weight (number average molecular weight of 300 to 80,000, preferably 400 to 5,000) polyester resin having an unsaturated double bond, a polyether resin, an acrylic resin, an epoxy resin, or an amine group can also be used. Acid ester resin, alkyd resin, acetal resin, polybutadiene tree A lipid, a polythiol polyene resin, an oxetane resin, or the like is used as the ultraviolet curable resin. In addition, the resin at this time contains all the dimers, oligomers, and polymers other than a monomer.

Preferred compounds in the present invention include compounds having three or more unsaturated bonds. When such a compound is used, the crosslinking density of the formed hard coat layer can be increased, and the hardness of the coating film can be improved.

Specifically, in the present invention, it is preferred to suitably combine pentaerythritol triacrylate, pentaerythritol tetraacrylate, polyester polyfunctional acrylate oligomer (3-15 functional), and urethane polyfunctional acrylate oligomerization. It is used as a substance (3 to 15 functional groups).

The ultraviolet curable resin may be used in combination with a solvent-drying resin (a resin which can be formed by drying a solvent which is added to adjust a solid component at the time of coating, and can form a film). By using a solvent-dried resin in combination, it is possible to effectively prevent film defects on the coated surface, and the solvent-drying resin which can be used in combination with the ultraviolet curable resin is not particularly limited, and a general thermoplastic resin can be used.

The photopolymerization initiator is not particularly limited, and those skilled in the art can be used. For example, as a photopolymerization initiator, acetophenone, diphenyl ketone, M. benzoyl benzoate, and α can be used. - amyl oxime ester, thioxanthone, propiophenone, diphenylethylenedione, benzoin, decylphosphine oxide. Further, it is preferably used by mixing a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, and poly-n-butylphosphine.

As the photopolymerization initiator, when the ultraviolet curable resin is a resin having a radical polymerizable unsaturated group, it may be used singly or in combination. Acetophenone, diphenyl ketone, thioxanthone, benzoin, benzoin methyl ether, and the like. Further, when the ultraviolet curable resin is a resin having a cationically polymerizable functional group, an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic sulfonium salt, or a metallocene compound may be used singly or in combination as a photopolymerization initiator. , benzoin sulfonate and the like.

When the photopolymerization initiator used in the present invention is an ultraviolet curable resin having a radical polymerizable unsaturated group, it is preferably 1-hydroxyl based on the compatibility with the ultraviolet curable resin and the yellowing resistance. -cyclohexyl-phenyl-ketone (trade name: Irgacure 184, manufactured by BASF Japan Co., Ltd.).

The content of the photopolymerization initiator in the composition for forming a hard coat layer is preferably in the range of 1.0 to 10 parts by mass based on 100 parts by mass of the ultraviolet curable resin. When the amount is 1.0 part by mass or more, the hardness of the hard coat layer can be a desired condition, and if it is 10 parts by mass or less, the ionizing radiation reaches the deep portion of the applied film to promote internal hardening. The desired pencil hardness of the target hard coat surface is preferably point.

A more preferred lower limit of the content of the photopolymerization initiator is 2.0 parts by mass, and a more preferred upper limit is 8.0 parts by mass. Since the content of the photopolymerization initiator is in this range, the hardness distribution does not occur in the film thickness direction, and the hard coat layer tends to have a uniform hardness.

The composition for forming a hard coat layer may further contain a solvent.

The solvent can be appropriately selected and used depending on the type and solubility of the ultraviolet curable resin component to be used, and examples thereof include a ketone (for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and An acetol or the like), an ether (for example, dioxane, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.), an aliphatic hydrocarbon (for example, hexane or the like), or an alicyclic hydrocarbon (for example, Cyclohexane or the like), aromatic hydrocarbons (for example, toluene, xylene, etc.), halogenated carbon (for example, dichloromethane, dichloroethane, etc.), esters (for example, methyl acetate, ethyl acetate, acetic acid) Ester, etc.), water, alcohol (eg, ethanol, isopropanol, butanol, cyclohexanone, etc.), cellosolve (eg, methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetate An ester, an anthracene (for example, dimethyl hydrazine or the like), a guanamine (for example, dimethylformamide, dimethylacetamide, etc.), or the like, or a mixed solvent thereof. Particularly, in the present invention, at least one of methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone or a mixture thereof is contained in the solvent of the ketone based on compatibility with the ultraviolet curable resin. The reason why the coating property is excellent is preferable.

Further, in the composition for forming a hard coat layer, the purpose of improving the hardness of the hard coat layer, suppressing the hardening shrinkage, preventing the adhesion, controlling the refractive index, imparting anti-glare property, and controlling the properties of the particles or the surface of the hard coat layer are also Conventional organic microparticles, inorganic microparticles, dispersants, surfactants, antistatic agents, decane coupling agents, tackifiers, colorants, colorants (pigments, dyes), defoamers, leveling agents, Flame retardant, tackifier, polymerization inhibitor, antioxidant, surface modifier, etc. Moreover, the composition for forming a hard coat layer may further contain a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, and poly-n-butylphosphine.

The preparation method of the composition for forming a hard coat layer is not particularly limited as long as it can uniformly mix the respective constituent components, and for example, a paint shaker, a bead mill, a kneader, a mixer, or the like can be used. A known device mixes and dissolves the constituent components to prepare.

In addition, the method of applying the composition for forming a hard coat layer to the first protective film of the present invention is not particularly limited, and examples thereof include a spin coating method, a dipping method, a spray method, and a die coating method. A well-known wet coating method such as a bar coating method, a roll coating method, a meniscus coating method, a flexographic printing method, a screen printing method, or a liquid coating method.

[2nd protective film]

The second protective film of the present invention is a protective film characterized by a light-transmitting film having a light transmittance of less than 50% at 380 nm, and a retardation value Ro (nm) in the film surface defined by the following formula (i). The hysteresis value Rt (nm) in the film thickness direction defined by the following formula (ii) satisfies the conditions defined by the following formula (iv), and the conditions defined by the following formula (iv) are satisfied.

(i) Ro = (n _{x -} n _y ) × d

(ii) Rt=((n _x +n _y )/2-n _z )×d

(iii) 40≦Ro≦300

(iv) 100≦Rt≦400

Wherein the refractive index in the direction of the slow phase axis in the plane of the n _x film; the refractive index in the direction perpendicular to the direction of the slow axis in the plane of the n _y film; n _z is the refractive index perpendicular to the direction of the film face; The thickness (nm) of the d-based film.

More preferably, the second protective film is preferably in the form of a cellulose resin or a form composed of a cycloolefin resin.

The hysteresis value of the second protective film can be measured in accordance with a well-known technique. Specifically, the hysteresis value Ro of the in-plane direction of the film and the hysteresis value Rt of the film thickness direction are as described above, and an Abis Scan Mueller Matrix Polarimeter (AXO METRIX) can be used. The three-dimensional refractive index measurement was carried out at a wavelength of 590 nm in an environment of 23 ° C ‧55% RH, and was calculated from the obtained refractive indices n _x , n _y , and n _z .

In the second protective film of the present invention, the hysteresis value Ro (nm) in the plane of the film represented by the above formula (i) is set to be within the range defined by the above formula (iii), and the above formula ( Ii) The hysteresis value Rt (nm) of the defined film thickness direction is set within the range defined by the above formula (iv). Here, as shown in the formula (iii), Ro is in the range of 40 ≦ Ro ≦ 300, more preferably 50 ≦ Ro ≦ 200, and particularly preferably 60 ≦ Ro ≦ 150. Further, in the formula (iv), Rt is in the range of 100 ≦ Rt ≦ 400, preferably in the range of 100 ≦ Rt ≦ 200.

When the hysteresis value Ro in the film surface of the second protective film and the hysteresis value Rt in the film thickness direction are set to the ranges defined by the above formulas (iii) and (iv), the polarizing plate is used as the second protective film. When the side is attached to the liquid crystal cell, light leakage during black display of the obtained liquid crystal display device can be effectively prevented. Moreover, since the thickness of the second protective film can be reduced, it is preferable to further reduce the thickness and weight of the polarizing plate and the liquid crystal display device.

Among the second protective films, one of the characteristics is a light-transmitting film having a light transmittance of less than 50% at 380 nm.

The light transmittance of the second protective film of the present invention at a wavelength of 380 nm can be determined, for example, by measurement using an ultraviolet-visible spectrophotometer (UV-Vis NIR spectrophotometer manufactured by JASCO Corporation, product name: V7100). It is characterized by a light transmittance of less than 50% at 380 nm, but preferably less than 25%, more preferably less than 10%.

In the second protective film of the present invention, as a method of making the light transmittance at 380 nm less than 50%, an additive having light absorption at 380 nm is added to the film, and particularly effective for addition in the ultraviolet region is strong. UV absorbing agent for absorption capacity.

Hereinafter, the details of the second protective film of the present invention will be further described.

[Cellulose Resin Film]

One of preferred embodiments of the second protective film of the present invention is a cellulose resin film containing a cellulose resin.

The cellulose resin used for the second protective film of the polarizing plate may, for example, be a cellulose ester resin, a cellulose ether resin or a cellulose ether ester resin.

The cellulose ester to be used for the second protective film is not particularly limited, but the cellulose ester is a carboxylate having a carbon number of from 2 to 22, and may be an ester of an aromatic carboxylic acid, particularly preferably a lower cellulose. Fatty acid esters.

The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The thiol group bonded to the hydroxy group may be straight or branched, and may also form a ring. Furthermore, other substituents may be substituted. In the case of the same degree of substitution, the more the carbon number is, the lower the birefringence is. Therefore, the carbon number is preferably selected from the group of 2 to 6 carbon atoms. The carbon number of the cellulose ester is preferably 2 to 4, and the carbon number is preferably 2 to 2. 3.

The cellulose ester may also be a thiol group derived from a mixed acid, and particularly preferably a fluorenyl group having 2 to 3 carbon atoms or 2 to 4 carbon atoms. In the present invention, as the cellulose ester, in addition to using, for example, cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate, a propionate group or A mixed fatty acid ester of cellulose bound by a butyrate group. Further, as the butyric acid group forming the butyrate, it may be linear or branched. As the cellulose ester which is preferably used in the present invention, in particular, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate.

Further, the hysteresis value can be suitably controlled by the kind of the above mercapto group of the cellulose ester and the degree of substitution of the mercapto group with the pyranose ring of the cellulose resin skeleton.

In the present invention, a preferred cellulose ester satisfies the following formulae (A) and (B).

Formula (A) 2.0≦X+Y≦3.0

Equation (B)0≦Y≦2.0

In the above formula (A) and formula (B), the degree of substitution of the X-based acetyl group and the degree of substitution of the Y-based propyl group or the butyl group. The cellulose ester which satisfies the above formula (A) and formula (B) is suitable for producing a protective film for a polarizing plate which exhibits excellent optical characteristics.

Among them, it is particularly preferred to use acetaminophen cellulose or cellulose acetate propionate.

In cellulose acetate propionate or cellulose acetate butyrate, 1.5 ≦ X ≦ 2.9, 0.1 ≦ Y ≦ 1.5, 2.0 ≦ X + Y ≦ 3.0 is preferred. The method for determining the degree of substitution of the thiol group can be measured in accordance with ASTM-D817-96.

When the degree of substitution of the above mercapto group is too low, the unreacted portion of the hydroxyl group of the pyranose ring constituting the skeleton of the cellulose resin is increased, and the hydroxyl group remains frequently, and the humidity is changed as a hysteresis or the protection for the polarizing plate. The ability of the membrane to protect the polarizer is not desirable.

When the number average molecular weight of the cellulose ester used in the present invention is in the range of 60,000 to 300,000, the obtained film has a strong mechanical strength and is preferable. Furthermore, it is better to use those in the range of 70,000 to 200,000.

The number average molecular weight of the cellulose ester can be determined by high speed liquid chromatography under the following conditions.

Solvent; acetone

Pipe column: MPW×1 (Dongcao (share) system)

Sample concentration: 0.2 (mass/capacity)%

Flow rate: 1.0mL/min

Sample injection amount: 300 μL

Standard sample: standard polystyrene

Temperature: 23 ° C

The cellulose which is a raw material of the cellulose ester is not particularly limited. Cotton velvet, wood pulp, kenaf and the like can be mentioned. Further, the cellulose esters obtained by the above may be used in combination at any ratio.

Cellulose ester When the deuteration agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), a solvent such as an organic acid of acetic acid or dichloromethane is used, and a protonic catalyst such as sulfuric acid is used. reaction. When ruthenium chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl) is used as the oximation agent, the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by referring to the method described in JP-A-10-45804.

In the cellulose ester, the average degree of substitution of the thiol group at the 6-position of the glucose unit is preferably 0.5 to 0.9.

The 6th position of the glucose unit constituting the cellulose ester is different from the 2nd position and the 3rd position, and a highly reactive primary hydroxyl group exists. This primary hydroxyl group preferentially forms a sulfate in the production process of a cellulose ester using sulfuric acid as a catalyst. Therefore, in the esterification reaction of cellulose, by increasing the amount of the catalyst sulfuric acid, the average degree of substitution between the 2 and 3 positions can be increased compared to the usual cellulose ester by 6 bits of the glucose unit. Further, if the cellulose is tritylated as needed, the hydroxyl group at the 6th position of the glucose unit can be selectively protected, and the hydroxyl group at the 6 position can be protected by tritylation and esterified. By detaching the trityl group (protecting group), the average degree of substitution of the 2 and 3 positions can be increased more than the 6th position of the glucose unit. Specifically, a cellulose ester produced by the method described in JP-A-2005-281645 can also be preferably used.

In the case of acetaminophen, if you want to increase the acetylation rate, The time for the acetamidine reaction must be extended. However, if the reaction time is too long, the decomposition system proceeds simultaneously, causing the cutting of the polymer chain or the decomposition of the acetyl group, and the like, which also causes unfavorable results. Therefore, in order to increase the degree of acetylation and to suppress decomposition to a certain extent, the reaction time must be set within a certain range. It is not appropriate to specify the reaction time because the applicable reaction conditions are various and vary greatly depending on other conditions such as a reaction apparatus or equipment. Since the molecular weight distribution becomes broad as the decomposition of the polymer proceeds, the degree of decomposition in the case of the cellulose ester can also be defined by the ratio of the weight average molecular weight (Mw) / the number average molecular weight (Mn) which are usually used. That is, in the process of acetylation of cellulose triacetate, as an indicator of the degree of reaction which does not excessively decompose and does not excessively proceed and acetylation reaction is sufficiently carried out in acetonitrile, a weight average molecular weight can be used. (Mw) / ratio of the number average molecular weight (Mn).

An example of a method for producing a cellulose ester is shown below.

100 parts by mass of cotton wool as a cellulose raw material was decomposed and pulverized, and 40 parts by mass of acetic acid was added thereto, and activation treatment was carried out at 36 ° C for 20 minutes. Then, 8 parts by mass of sulfuric acid, 260 parts by mass of acetic anhydride, and 350 parts by mass of acetic acid were added, and esterification was carried out at 36 ° C for 120 minutes. After neutralizing with 11 parts by mass of a 24% magnesium acetate aqueous solution, saponification was carried out at 63 ° C for 35 minutes to obtain acetonitrile cellulose. The obtained acetonitrile cellulose was stirred at room temperature for 160 minutes using a 10-fold aqueous acetic acid solution (acetic acid: water = 1:1 (mass ratio)), and then filtered and dried to obtain a refining degree of substitution of 2.75. Acetyl cellulose. The acetonitrile cellulose had a Mn of 92,000, a Mw of 156,000 and a Mw/Mn of 1.7. Similarly, by tune The esterification conditions (temperature, time, stirring) and hydrolysis conditions of the cellulose ester can synthesize a cellulose ester having a different degree of substitution and a ratio of Mw/Mn. The ratio of Mw/Mn of the cellulose ester is preferably in the range of 1.4 to 5.0.

Further, the cellulose ester to be synthesized is also preferably subjected to an operation of performing purification to remove a low molecular weight component, or an operation of filtering out a component which is not acetylated or has a low degree of acetylation.

Further, in the case of the acidified cellulose ester, it can be obtained by the method described in JP-A-10-45804.

The properties of cellulose esters are also affected by trace metal components in the cellulose ester. It is considered that these systems are related to the water used in the process, but the less the component of the metal component or the like that can become an insoluble core, the better the metal ions such as iron, calcium, magnesium, etc. have organic acid groups. It is preferable that the polymer decomposition product or the like is formed by salt formation to form an insoluble matter. The iron (Fe) component is preferably 1 ppm or less. The calcium (Ca) component is likely to form a complex compound, that is, a complex compound, with an acidic component such as a carboxylic acid or a sulfonic acid, and a plurality of complexes, and forms a large amount of residue (insoluble precipitate or turbidity) derived from insoluble calcium.

The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, particularly preferably in the range of 0 to 20 ppm, since it is too large to form an insoluble component. a metal component such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc., which can be decomposed by sulfuric acid in an ultra-digested wet decomposition apparatus by using an absolutely dried cellulose ester. After pretreatment with alkali melting, analysis is performed using ICP-AES (inductively coupled plasma luminescence spectroscopic analyzer) Seek.

In addition to the cellulose ester resin described above, a cellulose ether resin, a cellulose ether ester resin, and the like can be given.

A part or all of the hydroxyl group of the cellulose ether-based cellulose component is substituted with an alkoxy group. The carbon number of the alkoxy group is not particularly limited, but is preferably in the range of 2 to 20. Examples of such an alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like, and a methoxy group or an ethoxy group is preferred, and an ethoxy group is more preferred. The alkoxy group contained in the cellulose ether resin may be one type or two or more types.

In a specific example of the cellulose ether resin, methyl cellulose, ethyl cellulose or the like is contained, and ethyl cellulose is preferred.

The total degree of substitution of the alkoxy group of the cellulose ether resin is not particularly limited, but may be 1.5 or more and less than 3.0, preferably 2.0 or more and less than 3.0, more preferably 2.5 or more and 2.9 or less. The degree of substitution of the alkoxy group can be determined by the method described in ASTM D4794-94.

The weight average molecular weight or molecular weight distribution of the cellulose ether resin can be adjusted to the same range as the cellulose ester resin.

In addition, the cellulose ether resin or the cellulose ether ester resin described in, for example, Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. 2005-99997, and the like. Use it the same way.

(Additive for cellulose resin film)

In the cellulose resin film constituting the second protective film of the present invention, Various additives are used for their respective purposes.

[hysteresis riser]

Next, the details of the hysteresis rising agent will be described. The hysteresis-increasing agent is a compound having a hysteresis value of a film at a measurement wavelength of 590 nm, in particular, a hysteresis Rt in the thickness direction, which is larger than a function in which a hysteresis-increasing agent is not added.

In the second protective film including the hysteresis rising agent, the retardation Ro in the in-plane direction of the second protective film and the retardation Rt in the thickness direction are in the range defined by the following formulas (iii) and (iv) of the present invention. It is preferable to use the second protective film.

(iii) 40≦Ro≦300

(iv) 100≦Rt≦400

In the present invention, a nitrogen-containing heterocyclic compound having a molecular weight of from 100 to 800 can be used as a retardation increasing agent. Among them, the nitrogen-containing heterocyclic compound is preferably a compound having a structure represented by the following formula (1). By using a compound having a structure represented by the following formula (1) together with a cellulose resin, it is possible to realize a second protective film of Ro and Rt within the range defined by the present invention, and also to suppress fluctuations in humidity due to the environment. The resulting delay in the change.

(compound having the structure represented by the general formula (1))

In the above formula (1), A ₁ , A ₂ and B each independently represent an alkyl group (for example, methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl, 2-ethyl) A hexyl group or the like, a cycloalkyl group (for example, a cyclohexyl group, a cyclopentyl group, a 4-n-dodecylcyclohexyl group, etc.), an aromatic hydrocarbon ring or an aromatic heterocyclic ring (except that the pyrimidine ring and the pyridine ring are not included). Among them, an aromatic hydrocarbon ring or an aromatic heterocyclic ring is preferred, and an aromatic hydrocarbon ring or an aromatic heterocyclic ring of 5 or 6 members is particularly preferred.

The structure of the aromatic hydrocarbon ring or the aromatic heterocyclic ring of 5 or 6 members is not limited, and examples thereof include a benzene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, and a 1,2,3-triazole ring. 2,4-triazole ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxazole ring, thiophene ring, thiazole ring, isothiazole ring, thiadiazole ring, Isothiadiazole ring and the like.

The aromatic hydrocarbon ring or the aromatic heterocyclic ring of 5 or 6 members represented by A ₁ , A ₂ and B may have a substituent. The substituent may, for example, be a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom) or an alkyl group (for example, a methyl group, an ethyl group, a n-propyl group, an isopropyl group or a third group). Base, n-octyl, 2-ethylhexyl, etc.), cycloalkyl (eg, cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl, etc.), alkenyl (eg, vinyl, allyl, etc.) , a cycloalkenyl group (for example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl, etc.), an alkynyl group (for example, an ethynyl group, a propynyl group, etc.), an aromatic hydrocarbon ring group ( For example, phenyl, p-tolyl, naphthyl, etc., an aromatic heterocyclic group (for example, 2-pyrrolyl, 2-furyl, 2-thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, Benzimidazolyl, benzoxazolyl, 2-benzothiazolyl, pyrazolone, pyridyl, pyridinyl, 2-pyrimidinyl, triazinyl, pyrazolyl, 1,2,3- Triazolyl, 1,2,4-triazolyl, oxazolyl, isoxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiazolyl, isothiazole Base, 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, etc.), cyano, hydroxy, nitro, carboxyl, alkoxy (methoxy, Oxyl, isopropoxy, tert-butoxy, n-octyloxy, 2-methoxyethoxy, etc.), aryloxy (eg, phenoxy, 2-methylphenoxy, 4- a third butyl phenoxy group, a 3-nitrophenoxy group, a 2-tetradecylaminophenoxy group, etc.), a decyloxy group (for example, a methyloxy group, an ethoxy group, a trimethyl group) An alkoxy group, a stearyloxy group, a benzyl methoxy group, a p-methoxyphenylcarbonyloxy group, etc., an amine group (for example, an amine group, a methylamino group, a dimethylamino group, an anilino group, N-methyl-anilino, diphenylamino, etc.), mercaptoamine (for example, formamylamine, etidylamino, trimethylethenylamine, laurylamine, a benzhydrylamino group, etc., an alkyl group and an arylsulfonylamino group (eg, methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, 2, 3, 5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino, etc., mercapto, alkylthio (eg, methylthio, ethylthio, n-hexadecylthio, etc.), An arylthio group (for example, phenylthio, p-chlorophenylthio, m-methoxyphenylthio, etc.), an amine sulfonyl group (for example, N-ethylamine sulfonyl, N-(3-ten) Dimethoxypropyl)amine sulfonyl, N,N-dimethylamine sulfonyl, N-acetamimidoxime, N-benzamidesulfonyl, N-(N' -Phenylamine-mercapto)aminesulfonyl, etc., sulfo, fluorenyl (for example, ethyl ethenyl, trimethylethyl benzyl fluorenyl, etc.), amine carbenyl (for example, amine formazan) Base, N-methylamine methyl sulfhydryl, N,N-dimethylaminecarbamyl, N,N-di-n-octylamine methyl sulfhydryl, N-(methylsulfonyl)amine methyl sulfhydryl, etc. ) and so on.

In the above formula (1), A ₁ , A ₂ and B preferably each represent a benzene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring or 1,2,4-three. The azole ring is a deuterated cellulose film which is excellent in the effect of changing the optical characteristics and excellent in durability.

In the above formula (1), T ₁ and T ₂ each independently preferably represent a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring or a 1,2,4-triazole ring. Among these, a pyrazole ring, a triazole ring, or an imidazole ring is preferable, and a resin composition which is excellent in the effect of suppressing the change in hysteresis due to humidity fluctuation and excellent in durability is preferable, and a pyrazole ring is particularly preferable. . The pyrazole ring, the 1,2,3-triazole ring or the 1,2,4-triazole ring or the imidazole ring represented by T ₁ and T ₂ may also be a tautomer.

The specific structures of the pyrrole ring, the pyrazole ring, the imidazole ring, the 1,2,3-triazole ring or the 1,2,4-triazole ring are shown below.

In the formula, the * mark indicates the binding position to L ₁ , L ₂ , L ₃ or L _{4 in} the formula (1).

A hydrogen atom or a non-aromatic substituent represented by R ⁵ . The non-aromatic substituent represented by R ⁵ may be the same as the non-aromatic substituent among the substituents which A ₁ in the above formula (1) may have. When the substituent represented by R ^{5 is} a substituent having an aromatic group, since A ₁ and T ₁ or B and T ₁ are easily distorted, A ₁ , B and T ₁ cannot form an interaction with deuterated cellulose. It is difficult to suppress variations in optical characteristics. R ^{5 is} preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a fluorenyl group having 1 to 5 carbon atoms, particularly preferably a hydrogen atom, in order to improve the effect of suppressing fluctuation in optical properties.

In the above formula (1), each of T ₁ and T ₂ may have a substituent, and examples of the substituent include the same substituents as those of A ₁ and A ₂ in the above formula (1). .

In the above formula (1), L ₁ , L ₂ , L ₃ and L ₄ each independently represent a single bond or a divalent linking group, and a 5- or 6-membered aromatic hydrocarbon ring is bonded via two or less atoms. Or an aromatic heterocyclic ring. The atom that is separated by two or less atoms is the smallest atomic number existing between the substituents connected to the atoms constituting the linking group. The divalent linking group having two or less linked atoms is not particularly limited, but is selected from an alkyl group, an alkenyl group, an alkynyl group, O, (C=O), NR, S, (O = S=O) A divalent linking group of the group consisting of, or a combination of two of them. R represents a hydrogen atom or a substituent. In the case of the substituent represented by R, an alkyl group (for example, methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.), naphthene is contained. a group (for example, a cyclohexyl group, a cyclopentyl group, a 4-n-dodecylcyclohexyl group, etc.), an aromatic hydrocarbon ring group (for example, a phenyl group, a p-tolyl group, a naphthyl group, etc.), an aromatic heterocyclic group (for example, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl, 2-pyridyl, etc.), cyano and the like. Each of the divalent linking groups represented by L ₁ , L ₂ , L ₃ and L ₄ may have a substituent, and is particularly limited as a substituent, and examples thereof include A ₁ in the above formula (1) and A ₂ may have the same substituent as the substituent.

In the above formula (1), L ₁ , L ₂ , L ₃ and L ₄ interact with the resin which adsorbs water in order to increase the planarity of the compound having the structure represented by the above formula (1). Strongening, suppressing variations in optical characteristics, preferably single bond or O, (C=O)-O, O-(C=O), (C=O)-NR or NR-(C=O), Good for a single button.

In the above formula (1), n represents an integer of 0 to 5. When n represents an integer of 2 or more, the plural A ₂ , T ₂ , L ₃ , and L ₄ in the above formula (1) may be the same or different. The larger the n, the stronger the interaction between the compound having the structure represented by the above formula (1) and the resin that adsorbs water, so that the effect of suppressing fluctuation in optical characteristics is excellent, and the smaller the n, the phase of the resin adsorbing water The solubility is superior. Therefore, n is preferably an integer of 1 to 3, more preferably an integer of 1 to 2.

(compound having a structure represented by the general formula (2))

The compound having a structure represented by the formula (1) described above is more preferably a compound having a structure represented by the following formula (2).

In the above formula (2), A ₁ , A ₂ , T ₁ , T ₂ , L ₁ , L ₂ , L ₃ and L ₄ are each independently A ₁ , A ₂ , T ₁ in the above formula (1). T ₂ , L ₁ , L ₂ , L ₃ and L _{4 are} synonymous. A ₃ and T ₃ each represent the same group as A ₁ and T ₁ in the formula (1). L ₅ and L ₆ represent the same groups as those of L ₁ in the above formula (1). m represents an integer from 0 to 4.

The smaller the m, the better the compatibility with deuterated cellulose. Preferably, m is preferably an integer of 0 to 2, more preferably 0 or 1.

(compound having a structure represented by the general formula (1.1))

The compound having a structure represented by the formula (1) described above is more preferably a triazole compound having a structure represented by the following formula (1.1).

In the above formula (1.1), each of A ₁ , B, L ₁ and L ₂ represents the same group as A ₁ , B, L ₁ and L ₂ in the above formula (1). k represents an integer from 1 to 4. T ₁ represents a 1,2,4-triazole ring.

In addition, the triazole compound having a structure represented by the above formula (1.1) is preferably a triazole compound having a structure represented by the following formula (1.2).

In the above formula (1.2), Z is a partial structure represented by the following formula (1.2a). q represents an integer from 2 to 3. At least two Z-links are bonded to the ortho or meta position relative to at least one Z substituted on the phenyl ring.

In the above formula (1.2a), R ¹⁰ represents a hydrogen atom, an alkyl group or an alkoxy group. p represents an integer from 1 to 5. * indicates the position of binding to the benzene ring. T ₁ represents a 1,2,4-triazole ring.

The compound having a structure represented by the formula (1), (2), (1.1) or (1.2) may also form a hydrate, a solvate or a salt. Further, in the present invention, the hydrate may also contain an organic solvent, and the solvate may also contain water. That is, the "hydrate" and "solvate" include a mixed solvate containing either water or an organic solvent. As the salt, an acid addition salt formed with an inorganic or organic acid is contained. Examples of the inorganic acid include hydrohalic acid (hydrochloric acid, hydrobromic acid, etc.), sulfuric acid, phosphoric acid, and the like, but are not limited thereto. Further, examples of the organic acid include acetic acid, trifluoroacetic acid, propionic acid, butyric acid, oxalic acid, citric acid, benzoic acid, alkylsulfonic acid (methanesulfonic acid, etc.), and allylsulfonic acid (benzene). Sulfonic acid, 4-toluenesulfonic acid, 1,5-naphthalenedisulfonic acid, etc.), etc., but are not limited by these. Among these, a hydrochloride, an acetate, a propionate, and a butyrate are preferable.

As an example of the salt, an acidic moiety present in the parent compound may be exemplified by a metal ion (for example, an alkali metal salt, a sodium or potassium salt, an alkaline earth metal salt, a calcium or magnesium salt, an ammonium salt alkali metal ion, an alkaline earth metal ion). Or aluminum ion, etc. substituted or with an organic base (eg, ethanolamine, diethanolamine, three The salt formed during the preparation of ethanolamine, morpholine, piperidine, etc., is not limited by these. Among these, a sodium salt or a potassium salt is preferred.

Examples of the solvent contained in the solvate include all common organic solvents. Specific examples thereof include alcohols (for example, methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, and third butanol) and esters (for example, ethyl acetate). And a hydrocarbon (for example, toluene, hexane, pentane), an ether (for example, tetrahydrofuran), a nitrile (for example, acetonitrile), a ketone (for example, acetone), or the like. A solvate of an alcohol (for example, methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, butanol) is preferred. These solvents may be the reaction solvent used in the synthesis of the above compounds, or the solvent used in the crystallization purification after the synthesis, or may be mixed for the like.

Further, two or more types of solvents may be contained at the same time, and may be in the form of water and a solvent (for example, water and an alcohol (for example, methanol, ethanol, butanol, etc.)).

Further, the compound having the structure represented by the formula (1), (2), (1.1) or (1.2) may be added in the form of no water, solvent or salt, or may be added to the second protective film of the present invention. In the formation of a hydrate, solvate or salt.

The molecular weight of the compound having the structure represented by the general formula (1), (2), (1.1) or (1.2) is not particularly limited, but the smaller the compatibility with the cellulose resin, the larger the larger the larger the compatibility. The higher the suppression effect of the optical value on the change of the ambient humidity, the better it is 150 to 2000, more preferably 200 to 1500, and particularly preferably 300 to 1000.

(compound having a structure represented by the general formula (3))

The nitrogen-containing heterocyclic compound which can be suitably used in the present invention is more preferably a compound having a structure represented by the following formula (3).

In the above formula (3), A represents a pyrazole ring, and each of Ar ₁ and Ar ₂ represents an aromatic hydrocarbon ring or an aromatic hetero ring, and may have a substituent. R ₁ represents a hydrogen atom, an alkyl group, a decyl group, a sulfonyl group, an alkoxycarbonyl group or an aryloxycarbonyl group, and q represents an integer of 1 to 2, and n and m each represent an integer of 1 to 3.

Each of the aromatic hydrocarbon ring or the aromatic heterocyclic ring represented by Ar ₁ and Ar _{2 is} preferably an aromatic hydrocarbon ring or an aromatic heterocyclic ring of 5 or 6 members as exemplified in the above formula (1). In addition, examples of the substituent of Ar ₁ and Ar ₂ include the same substituents as those shown for the compound having the structure represented by the formula (1).

Specific examples of R ₁ include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), and an alkyl group (for example, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, and a third group). Butyl, n-octyl, 2-ethylhexyl, etc.), fluorenyl (for example, ethyl ethenyl, trimethylethyl benzyl fluorenyl, etc.), sulfonyl (for example, methylsulfonyl, ethyl A sulfonyl group or the like, an alkoxycarbonyl group (e.g., a methoxycarbonyl group, etc.), an aryloxycarbonyl group (e.g., a phenoxycarbonyl group, etc.), and the like.

q represents an integer from 1 to 2, and n and m represent integers from 1 to 3.

Specific examples of the compound having an aromatic hydrocarbon ring or an aromatic heterocyclic ring of 5 or 6 members are exemplified below. The above-mentioned compound having an aromatic hydrocarbon ring or an aromatic hetero ring having 5 or 6 members is not limited to the specific examples below. Further, as described above, the following specific examples may be tautomers, and may also form a hydrate, a solvate or a salt.

Specific examples of the nitrogen-containing heterocyclic compound include an international public number in addition to the above-exemplified exemplary compounds 1 to 3. The compound described in paragraphs (0140) to (0214) of WO2014/109350A1. However, a nitrogen-containing heterocyclic compound having a pyrimidine ring or a pyridine ring is not included.

(Synthesis method of a compound having a structure represented by the general formula (1))

Next, a method for synthesizing the nitrogen-containing heterocyclic compound having the structure represented by the formula (1) will be described.

The above compound having a structure represented by the formula (1) can be synthesized by a known method. In the above compound having a structure represented by the formula (1), the compound having a 1,2,4-triazole ring may be any starting material, but it is preferred to use a nitrile derivative or an imino ether derivative. A method of reacting an anthracene derivative. The solvent to be used in the reaction may be any solvent as long as it is a solvent which does not react with the raw material, and examples thereof include an ester (for example, ethyl acetate or methyl acetate) and a guanamine (for example, dimethylformamide, Dimethylacetamide, etc.), ether (eg, ethylene glycol dimethyl ether, etc.), alcohol (eg, methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, ethylene glycol) , ethylene glycol monomethyl ether, etc.), aromatic hydrocarbons (for example, toluene, xylene, etc.), water. The solvent to be used is preferably an alcohol solvent. Further, these solvents may also be used in combination.

The amount of the solvent to be used is not particularly limited, but is preferably in the range of 0.5 to 30 times, more preferably 1.0 to 25 times, and particularly preferably 3.0 to 20 times, based on the mass of the anthracene derivative to be used. Within the range of multiples.

When the nitrile derivative is reacted with the anthracene derivative, the catalyst may not be used, but in order to accelerate the reaction, a catalyst is preferably used. Used as For the catalyst, an acid or an alkali can be used. The acid may, for example, be hydrochloric acid, sulfuric acid, nitric acid or acetic acid, and is preferably hydrochloric acid. The acid may also be added by dilution in water or may be added by blowing a gas into the system. As the base, an inorganic base (for example, potassium carbonate, sodium carbonate, potassium hydrogencarbonate, sodium hydrogencarbonate, potassium hydroxide, sodium hydroxide or the like) and an organic base (for example, sodium methoxide, sodium ethoxide, and methoxy potassium) can be used. , ethoxy potassium, sodium butoxide, potassium butoxide, diisopropylethylamine, N,N'-dimethylaminopyridine, 1,4-diazabicyclo[2.2.2]octane, N- Any one of methylmorpholine, imidazole, N-methylimidazole, pyridine, etc., as the inorganic base, potassium carbonate is preferred, and as the organic base, sodium ethoxide, sodium ethoxide or sodium butoxide is preferred. The inorganic base may be added directly as a powder or may be added in a state of being dispersed in a solvent. Further, the organic base may be added in a state of being dissolved in a solvent (for example, a 28% methanol solution of sodium methoxide or the like).

The amount of the catalyst used is not particularly limited as long as it is the amount of the reaction, but it is preferably in the range of 1.0 to 5.0 times the molar amount, more preferably 1.05 to 3.0 times the molar amount of the triazole ring to be formed. Within the scope.

When the imino ether derivative is reacted with an anthracene derivative, it is not necessary to use a catalyst, and the object can be obtained by heating in a solvent.

The method of adding the raw materials, the solvent and the catalyst used in the reaction is not particularly limited, but the catalyst may be added last or the solvent may be added last. Further, a method in which a nitrile derivative is dispersed or dissolved in a solvent, and a catalyst is added, and a method of adding an anthracene derivative is also preferred.

The temperature of the solution in the reaction may be any temperature as long as it is the temperature at which the reaction proceeds, but is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 140 ° C. Moreover, it is also possible to remove the generated water, one The reaction is carried out.

The treatment method of the reaction solution may be any means, but when a base is used as the catalyst, a method of neutralizing the acid in the reaction solution is preferred. The acid used for the neutralization may, for example, be hydrochloric acid, sulfuric acid, nitric acid or acetic acid, and particularly preferably acetic acid. The amount of the acid to be used for the neutralization is not particularly limited as long as the pH of the reaction solution is in the range of 4 to 9, but it is preferably 0.1 to 3 times the molar amount, particularly preferably 0.2%, based on the alkali to be used. 1.5 times the range of Moule.

As a treatment method of the reaction solution, when extraction is carried out using a suitable organic solvent, it is preferred to carry out concentration after washing the organic solvent with water after extraction. The suitable organic solvent as used herein is a water-insoluble solvent such as ethyl acetate, toluene, dichloromethane or ether, or a mixed solvent of the aforementioned water-insoluble solvent and tetrahydrofuran or an alcohol solvent, preferably ethyl acetate. .

When the compound having the structure represented by the general formula (1) is crystallized, it is not particularly limited, but a method of adding crystals to the neutralized reaction solution to crystallize or preferably has a general formula (1) A method in which a dissolved aqueous solution of a compound of the structure is neutralized to cause crystallization.

<Synthesis of Compound 1>

The exemplified compound 1 can be synthesized according to the following scheme.

In 520 mL of dehydrated tetrahydrofuran (THF), 80 g (0.67 mol) of acetophenone and 52 g (0.27 mol) of dimethyl isophthalate were added, and the mixture was stirred while cooling with ice water under a nitrogen atmosphere, and dropped little by little. Sodium amination 52.3 g (1.34 mol). After stirring under ice cooling for 3 hours, it was stirred under water cooling for 12 hours. After adding concentrated sulfuric acid to the reaction liquid and neutralizing, pure water and ethyl acetate were added to separate the layers, and the organic layer was washed with pure water. The organic layer was dried over MgSO.sub. The suspension was washed by adding methanol to the obtained crude crystals to obtain 55.2 g of Intermediate A.

Into 300 mL of tetrahydrofuran (THF) and 200 mL of ethanol (EtOH), 55 g (0.15 mol) of Intermediate A was added, and while stirring at room temperature, 18.6 g (0.37 mol) of hydrazine monohydrate was added little by little. After the completion of the dropwise addition, the mixture was heated under reflux for 12 hours. Add pure water and ethyl acetate to the reaction solution While liquid separation, the organic layer was washed with pure water. The organic layer was dried over MgSO.sub. The obtained crude crystals were purified by hexane gel chromatography (ethyl acetate / pentane) to afford 27 g.

The ¹ H-NMR spectrum of the obtained exemplified compound 1 is as follows. Further, in order to avoid complication of chemical shift due to the presence of tautomers, a few drops of trifluoroacetic acid were added to the measurement solvent to carry out measurement.

¹ H-NMR (400 MHz, solvent: heavy DMSO, standard: tetramethyl decane) δ (ppm): 8.34 (1H, s), 7.87-7.81 (6H, m), 7.55-7.51 (1H, m), 7.48 -7.44(4H,m), 7.36-7.33(2H,m),729(1H,s)

For other compounds, it can also be synthesized by the same method.

(How to use the compound having the structure represented by the general formula (1))

The compound having the structure represented by the formula (1) may be contained in the second protective film in an appropriate amount, but the amount of the resin is the total amount (100% by mass) of the resin constituting the second protective film. It is preferably contained in the range of 0.1 to 10% by mass, and particularly preferably in the range of 0.5 to 5% by mass. If it is within this range, the mechanical strength of the second protective film is not impaired, and the variation in the phase difference depending on the change in the environmental humidity can be reduced.

Moreover, as a method of adding the compound having the structure represented by the general formula (1), the powder may be added to a dope containing a resin capable of forming a second protective film, or may be added after being dissolved in a solvent. It is in the resin which can form a 2nd protective film.

Among the compounds having the structure represented by the formula (1), those having a benzene ring at the terminal (exemplary compounds 1 to 3, etc.) are used in a solution casting film forming method described later as a main solvent in dichloromethane. The solubility (saturated solubility) is as low as 10% by mass or less. Therefore, when such a poorly soluble compound is directly put into a dissolution vessel, an insoluble matter which is a cause of a bright foreign matter is generated. Therefore, when a poorly soluble compound is used among the nitrogen-containing heterocyclic compounds, it is preferred to add the above compound to a solvent (methylene chloride), stir and disperse it, and then put it into a dissolution vessel together with the resin forming the optical film. The method in the middle.

[ester]

The second protective film of the present invention preferably contains at least one selected from the group consisting of a sugar ester, a polyester compound, and a polyol ester as an ester.

When the above-mentioned polyester-based compound does not contain a nitrogen atom in the structure, it is liquidified and adheres to the filter when it is cooled in the production line, and the filter collection of the nitrogen-containing heterocyclic compound can be reduced. More suitable. Among them, since the sugar ester and the polycondensation ester have the function of a water-resistant plasticizer, it is preferable to suppress the variation of the retardation Rt due to water content.

(sugar ester)

The sugar ester is a compound containing at least one of a furanose ring and a pyranose ring, and may be a monosaccharide structure or a polysaccharide structure having 2 to 12 linked sugar structures. Further, the sugar ester is preferably at least one esterified compound having an OH group of a sugar structure, more preferably more than half of the OH group. Esterifier. For example, if the OH group of the sugar structure is eight, the average ester substitution degree of the sugar ester is preferably in the range of 4.0 to 8.0, more preferably in the range of 5.0 to 7.5.

The sugar ester is not particularly limited, and examples thereof include a sugar ester represented by the following formula (A).

Formula _{(A) (HO) m -G-} (OC (= O) -R 2) n

In the above formula (A), G represents a residue of a monosaccharide or a disaccharide, R ² represents an aliphatic group or an aromatic group, and m is a hydroxyl group directly bonded to a residue of a monosaccharide or a disaccharide. In total, n is a total of -(OC(=O)-R ² ) groups directly bonded to a residue of a monosaccharide or a disaccharide, 3≦m+n≦8, n≠0.

A sugar ester having a structure represented by the general formula (A) is known to be difficult to be isolated as a single compound having a hydroxyl number (cm) and a -(OC(=O)-R ² ) group (n). Among the components in which m and n are different, the compounds are mixed in several types. Therefore, the properties of the mixture in which the number of hydroxyl groups (cm) and -(OC(=O)-R ² ) groups (n) are each changed are important. When it is an optical film in the present invention, it is preferred that the average degree of ester substitution is Sugar esters in the range of 5.0 to 7.5.

In the above formula (A), G represents a residue of a monosaccharide or a disaccharide, and specific examples of the monosaccharide include, for example, allose, altrose, glucose, mannose, gulose, Idose, galactose, teraloose, ribose, arabinose, xylose, lyxose, etc.

The following shows monosaccharides having a sugar ester represented by the general formula (A) Specific examples of the compound of the residue are not limited by the compounds exemplified above.

Further, specific examples of the disaccharide residue include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and isotrehalose.

Specific examples of the compound having a disaccharide residue of the sugar ester represented by the general formula (A) are shown below, but are not limited by the compounds exemplified above.

In the formula (A), R ² represents an aliphatic group or an aromatic group. Here, the aliphatic group and the aromatic group are each independently a substituent.

Further, in the general formula (A), m is a total of the number of hydroxyl groups directly bonded to a residue of a monosaccharide or a disaccharide, and n is directly bonded to a residue of a monosaccharide or a disaccharide - ( OC(=O)-R ² ) The sum of the bases. Moreover, it is necessary to have 3 ≦ m + n ≦ 8, preferably 4 ≦ m + n ≦ 8. Also, n≠0. Further, when n is 2 or more, the -(OC(=O)-R ² ) groups may be the same or different.

The aliphatic group represented by R ² may be a straight chain, a branch, or a ring, preferably having a carbon number of 1 to 25, preferably 1 to 20, and particularly preferably 2 to 15. . Specific examples of the aliphatic group include methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, and the like. Third amyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, trioctyl, dodecyl, hexadecyl, octadecyl, diterpene Bases and so on.

Further, the aromatic group represented by R ² may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group. The aromatic hydrocarbon group is preferably a carbon number of 6 to 24, more preferably 6 to 12. Specific examples of the aromatic hydrocarbon group include each of benzene, naphthalene, anthracene, biphenyl, and terphenyl. The aromatic hydrocarbon group is particularly preferably a benzene ring, a naphthalene ring or a biphenyl ring. The aromatic heterocyclic group is preferably a ring containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, anthracene, oxazole, anthracene, thiazoline, and thiadiazole. , oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, pyridazine, naphthyridine, quinoxaline, quinazoline, porphyrin, pteridine, acridine, phenanthroline, phenazine, tetrazole Each of the rings of benzimidazole, benzoxazole, benzothiazole, benzotriazole, tetrahydroanthraquinone, and the like. The aromatic heterocyclic group is particularly preferably a pyridine ring, a triazine ring or a quinoline ring.

The sugar ester may contain two or more different substituents in one molecule, and may contain an aromatic substituent and an aliphatic substituent in one molecule, and contain two or more aromatic substituents in one molecule. One molecule contains two or more different aliphatic substituents.

Further, it is also preferred to contain two or more types of sugar esters. It is also preferred to contain both a sugar ester containing an aromatic substituent and a sugar ester containing an aliphatic substituent.

Hereinafter, preferred examples of the sugar ester represented by the general formula (A) are shown below, but are not limited by the compounds exemplified above.

<Synthesis Example: Synthesis Example of Sugar Ester Represented by General Formula (A)>

The synthesis example of a sugar ester is shown below.

In a four-necked flask equipped with a stirring device, a reflux condenser, a thermometer and a nitrogen inlet tube, 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, and 379.7 g (4.8 mol) of pyridine were respectively added. The temperature was raised while bubbling nitrogen gas from the nitrogen introduction tube while stirring, and the esterification reaction was carried out at 70 ° C for 5 hours. Next, the pressure in the flask was reduced to 4 × 10 ² Pa or less, and the excess pyridine was distilled off at 60 ° C, and then the pressure in the flask was reduced to 1.3 × 10 Pa or less, and the temperature was raised to 120 ° C to distill off the benzoic anhydride. Most of the benzoic acid. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous solution of sodium carbonate were added, and the mixture was stirred at 50 ° C for 30 minutes, and then left to stand to separate a toluene layer. Finally, 100 g of water was added to the toluene layer obtained by the separation, and after washing at room temperature for 30 minutes, the toluene layer was separated, and under reduced pressure (4 × 10 ² Pa or less), toluene was distilled off at 60 ° C to obtain a compound A. a mixture of -1, A-2, A-3, A-4 and A-5. The obtained mixture was analyzed by HPLC and LC-MASS, and as a result, A-1 was 7% by mass, A-2 was 58% by mass, A-3 was 23% by mass, A-4 was 9% by mass, and A-5 was 3 mass%. %, the average ester substitution degree of the sugar ester is 6.57. Further, one of the obtained mixtures was purified by gel column chromatography to obtain A-1, A-2, A-3, A-4 and A-5 each having a purity of 100%.

The amount of the sugar ester added is preferably in the range of 0.1 to 20% by mass, and more preferably in the range of 1 to 15% by mass, based on the resin constituting the optical film (for example, deuterated cellulose).

The sugar ester is preferably in the range of 10 to 300, more preferably in the range of 10 to 40.

(polyester compound)

In the second protective film of the present invention, a polyester compound having a structure represented by the following formula (4) is preferably used as the ester. The polyester compound is preferably contained in an amount of from 1 to 30% by mass, more preferably from 5 to 20% by mass, based on 100% by mass of the resin constituting the optical film. contain.

General formula (4)B ₃ -(G ₂ -A) _n -G ₂ -B ₄

In the above formula (4), B ₃ and B ₄ each independently represent an aliphatic or aromatic monocarboxylic acid residue or a hydroxyl group. G ₂ represents an alkanediol residue having 2 to 12 carbon atoms, an aryl diol residue having 6 to 12 carbon atoms, or an alkylene glycol residue having 4 to 12 carbon atoms. A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms. n represents an integer of 1 or more.

The polyester compound includes a polycondensation ester of a repeating unit obtained by reacting a dicarboxylic acid with a diol, A represents a carboxylic acid residue in the polycondensation ester, and G ₂ represents an alcohol residue.

The dicarboxylic acid-based aromatic dicarboxylic acid, the aliphatic dicarboxylic acid or the alicyclic dicarboxylic acid constituting the polyester compound is preferably an aromatic dicarboxylic acid. The dicarboxylic acid system may be one type or a mixture of two or more types. It is especially good for mixed aromatics and aliphatics.

The diol-based aromatic diol, the aliphatic diol or the alicyclic diol constituting the polyester compound is preferably an aliphatic diol, more preferably a diol having 1 to 4 carbon atoms. The diol system may be one type or two types or more. mixture.

Among them, it is preferred to include a repeating unit obtained by reacting a dicarboxylic acid containing at least an aromatic dicarboxylic acid with a diol having 1 to 8 carbon atoms, and more preferably comprising an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. A repeating unit obtained by reacting an acid dicarboxylic acid with a diol having 1 to 8 carbon atoms.

Both ends of the molecule of the polyester compound may or may not be blocked.

In the general formula (4), specific examples of the alkylenedicarboxylic acid represented by A include 1,2-ethanedicarboxylic acid (succinic acid) and 1,3-propanedicarboxylic acid (glutaric acid). ), derived from 1,4-butanedicarboxylic acid (adipate), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) 2 valence base. Specific examples of the alkenyl alkenyldicarboxylic acid constituting A include maleic acid, fumaric acid, and the like. Specific examples of the aryl dicarboxylic acid represented by A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, and 1,4-benzenedicarboxylic acid. 1,5-naphthalenedicarboxylic acid, and the like.

The A system may be one type or two or more types. Among them, A is preferably a combination of an alkylenedicarboxylic acid having 4 to 12 carbon atoms and an aryldicarboxylic acid having 8 to 12 carbon atoms.

G ₂ in the formula (4) represents a divalent group derived from an alkanediol having 2 to 12 carbon atoms, a divalent group derived from an aryl diol having 6 to 12 carbon atoms, or a carbon A divalent group derived from an alkylene glycol having an atomic number of 4 to 12.

An example of a divalent group derived from an alkanediol having 2 to 12 carbon atoms in G ₂ includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butane Alcohol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl -1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl- 1,3-propanediol (3,3-dihydroxymethylpentane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1 , 3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol and 1 a divalent group derived from 12-octadecanediol or the like.

An example of a divalent group derived from an aryl diol having 6 to 12 carbon atoms in G ₂ includes 1,2-dihydroxybenzene (catechol) and 1,3-dihydroxybenzene ( A divalent group derived from resorcinol, 1,4-dihydroxybenzene (hydroquinone) or the like. An example of a divalent group derived from an alkylene glycol having 4 to 12 carbon atoms in G, comprising diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tri A divalent group derived from propylene glycol or the like.

The G ₂ system may be one type or two or more types. Among them, G _{2 is} preferably a divalent group derived from an alkanediol having 2 to 12 carbon atoms, more preferably 2 to 5, most preferably 2 to 4.

Each of B ₃ and B ₄ in the formula (4) is a monovalent group or a hydroxyl group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

The aromatic ring-containing monocarboxylic acid in the monovalent group derived from the aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, and includes not only an aromatic ring directly bonded to a carboxyl group but also an aromatic ring. It is bonded to a carboxyl group via an alkyl group or the like. In the case of a monovalent group derived from an aromatic ring-containing monocarboxylic acid, benzoic acid, p-tert-butylbenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, dimethylbenzoic acid, and B are contained. Benzoyl A monovalent group derived from acid, n-propylbenzoic acid, aminobenzoic acid, ethoxylated benzoic acid, phenylacetic acid, 3-phenylpropionic acid or the like. Among them, benzoic acid and p-toluic acid are preferred.

In the case of a monovalent group derived from an aliphatic monocarboxylic acid, a 1 derived from acetic acid, propionic acid, butyric acid, caprylic acid, caproic acid, capric acid, dodecanoic acid, stearic acid, oleic acid or the like is included. Price base. Among them, a monovalent group derived from an alkyl monocarboxylic acid having an alkyl group having 1 to 3 carbon atoms is preferred, and an acetamino group (a monovalent group derived from acetic acid) is more preferred.

In the present invention, the weight average molecular weight of the polyester compound is preferably in the range of 500 to 3,000, more preferably in the range of 600 to 2,000. The weight average molecular weight can be determined by gel permeation chromatography (GPC).

Specific examples of the polyester-based compound having the structure represented by the general formula (4) are shown below, but are not limited thereto.

Hereinafter, an example of a method for synthesizing the polyester compound described above will be described.

<Polyester Compound P1>

180 g of ethylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2L four equipped with a thermometer, a stirrer, and a fast cooling tube. The flask was gradually heated while stirring in a nitrogen stream until it reached 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, the unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P1. The acid value was 0.20 and the number average molecular weight was 450.

<Polyester compound P2>

251 g of 1,2-propanediol, 103 g of phthalic anhydride, 244 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a thermometer, a stirrer, and a slow cooling tube. In a 2 L four-necked flask, the temperature was gradually raised while stirring in a nitrogen stream until it reached 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain the following polyester compound P2. The acid value was 0.10 and the number average molecular weight was 450.

<Polyester compound P3>

330 g of 1,4-butanediol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged with a thermometer, a stirrer, and a slow cooling. In a 2 L four-necked flask of a tube, the temperature was gradually increased while stirring in a nitrogen stream until it reached 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, the unreacted 1,4-butanediol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P3. The acid value was 0.50 and the number average molecular weight was 2000.

<Polyester compound P4>

251 g of 1,2-propanediol, 354 g of terephthalic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a fast cooling tube. The temperature was gradually raised while stirring in a nitrogen stream until it reached 230 °C. Side view The degree of polymerization was observed, and the dehydration condensation reaction was carried out. After completion of the reaction, the unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P4. The acid value was 0.10 and the number average molecular weight was 400.

<Polyester compound P5>

251 g of 1,2-propanediol, 354 g of terephthalic acid, 680 g of p-toluic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. The temperature was gradually raised while stirring in a nitrogen stream until it reached 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain the following polyester compound P5. The acid value was 0.30 and the number average molecular weight was 400.

<Polyester compound P6>

180 g of 1,2-propanediol, 292 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a fast cooling tube, and the mixture was placed in a nitrogen stream. The temperature was gradually raised while stirring until it reached 200 °C. While observing the degree of polymerization, while dehydrating Combined reaction. After completion of the reaction, the unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P6. The acid value was 0.10 and the number average molecular weight was 400.

<Polyester compound P7>

180 g of 1,2-propanediol, 244 g of phthalic anhydride, 103 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. In the middle, the temperature was gradually increased while stirring in a nitrogen stream until it reached 200 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, the unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P7. The acid value was 0.10 and the number average molecular weight was 320.

<Polyester compound P8>

251 g of ethylene glycol, 244 g of phthalic anhydride, 120 g of succinic acid, 150 g of acetic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. The temperature was gradually raised while stirring in a nitrogen stream until it reached 200 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, the unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound P8. The acid value was 0.50 and the number average molecular weight was 1200.

<Polyester compound P9>

In the same manner as the above-mentioned polyester compound P2, the reverse is changed. Under the conditions, a polyester compound P9 having an acid value of 0.10 and a number average molecular weight of 315 was obtained.

(polyol ester)

In the second protective film of the present invention, it is also preferred to contain a polyol ester as an ester. The polyol ester is preferably a compound composed of an ester of a divalent or higher aliphatic polyol and a monocarboxylic acid, and has an aromatic ring or a cycloalkyl ring in the molecule. It is preferably a 2 to 20 valent aliphatic polyol ester.

The polyol which is preferably used in the present invention is represented by the following formula (5).

General formula (5) R ₁₁ -(OH) _n

In the above formula (5), R ₁₁ represents an n-valent organic group, n represents a positive integer of 2 or more, and OH group represents an alcoholic and/or phenolic hydroxyl group.

Examples of preferred polyhydric alcohols include the following, but are not limited thereto.

Examples thereof include ribitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 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-hexane Alcohol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, Xylitol and the like.

Particularly preferred are triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol.

The monocarboxylic acid used in the synthesis of the polyol ester is not particularly limited, and a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid or the like can be used. When an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is used, it is preferable to improve moisture permeability and retention.

Examples of preferred monocarboxylic acids include the following, but are not limited thereto.

As the aliphatic monocarboxylic acid, a fatty acid having a linear or side chain having 1 to 32 carbon atoms can be preferably used. The carbon number is preferably from 1 to 20, and particularly preferably from 1 to 10. When acetic acid is contained, compatibility with cellulose acetate is preferably increased, and it is also preferred to use acetic acid and other monocarboxylic acids.

Preferred examples of the aliphatic monocarboxylic acid include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethylhexanoic acid, undecanoic acid, and lauric acid. Acid, tridecanoic acid, nutmeg, tannic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, wax acid, twenty-seven Saturated fatty acids such as acid, octadecanoic acid, tridecanoic acid, and tridecanoic acid, unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linoleic acid, and peanut oleic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid or derivatives thereof.

An example of a preferred aromatic monocarboxylic acid is an alkoxy group having 1 to 3 alkyl groups, a methoxy group or an ethoxy group introduced into a benzene ring of benzoic acid such as benzoic acid or toluic acid. , biphenyl carboxylic acid, naphthalene carboxylic acid, An aromatic monocarboxylic acid having two or more benzene rings, such as tetrahydronaphthalenecarboxylic acid, or a derivative thereof. Particularly preferred is benzoic acid.

The molecular weight of the polyol ester is not particularly limited, but is preferably in the range of 300 to 1,500, more preferably in the range of 350 to 750. The one having a large molecular weight is preferably difficult to volatilize, and is preferably small in terms of moisture permeability and compatibility with deuterated cellulose.

The carboxylic acid used in the synthesis of the polyol ester may be one type or a mixture of two or more types. Further, the OH group in the polyol may be all esterified, or a part of the OH group may remain as it is.

Hereinafter, specific compounds of the polyol ester are exemplified.

The polyol ester is preferably contained in the range of 0.5 to 5% by mass, more preferably in the range of 1 to 3% by mass, and particularly preferably in the range of 1 to 2% by mass, based on 100% by mass of the second protective film. .

Polyol esters can be combined according to conventional general synthetic methods to make.

[Other additives]

<plasticizer>

The second protective film may contain a plasticizer as needed. The plasticizer is not particularly limited, but is preferably a polyvalent carboxylate plasticizer, a glycolate plasticizer, a phthalate plasticizer, a fatty acid ester plasticizer, or an acrylic plasticizer. Elected. Furthermore, these plasticizers also function as hysteresis lowering agents.

The glycolate-based plasticizer is not particularly limited, but an alkyl phthalic acid alkyl glycolate can be preferably used. Examples of the alkyl phthalic acid alkyl glycolate include methyl phthalic acid methyl glycolate, ethyl phthalic acid ethyl glycolate, and propyl phthalate. Mercaptopropyl glycolate, butyl phthalic acid butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalic acid ethyl glycolate, ethyl benzene Dimethylhydrazine methyl glycolate, ethyl phthalic acid propyl glycolate, methyl phthalic acid butyl glycolate, ethyl phthalic acid butyl glycolate, butyl Isophthalic acid methyl glycolate, butyl phthalic acid ethyl glycolate, propyl phthalic acid butyl glycolate, butyl phthalic acid propyl glycolate , methyl phthalic acid octyl glycolate, ethyl phthalic acid octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl ethoxide Acid esters, etc.

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

Examples of the citrate-based plasticizer include etidinyl trimethyl citrate, ethyl citrate triethyl acrylate, and ethyl tributyl tributyl citrate.

Examples of the fatty acid ester-based plasticizer include butyl oleate, methyl phthalate of ricinoleic acid, and dibutyl sebacate.

Examples of the phosphate-based plasticizer include triphenyl phosphate, tricresyl phosphate, tolyldiphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, and phosphoric acid. Butyl ester and the like.

The polyvalent carboxylate compound is composed of an ester of a polyvalent carboxylic acid having a valence of 2 or more, preferably 2 to 20, and an alcohol. Further, the aliphatic polycarboxylic acid preferably has a valence of 2 to 20, and when it is an aromatic polycarboxylic acid or an alicyclic polycarboxylic acid, it is preferably 3 to 20 valence.

The polycarboxylic acid is represented by the following formula (C).

General formula (C)R ₂ (COOH) _m (OH) _n

In the above formula (C), R ₂ represents an organic group of (m+n) valence, m represents a positive integer of 2 or more, n represents an integer of 0 or more, a COOH group represents a carboxyl group, and an OH group represents an alcoholic or phenolic hydroxyl group. .

Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited thereto. It is more suitable to use, for example, trimellitic acid, An aromatic polycarboxylic acid having a trivalent or higher valence of trimesic acid or pyromellitic acid or a derivative thereof, such as succinic acid, adipic acid, sebacic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, An aliphatic polycarboxylic acid such as tartaric acid, hydroxymalonic acid, malic acid, hydroxypolycarboxylic acid of citric acid or the like. In particular, those using a hydroxypolycarboxylic acid are preferred in terms of improvement in retention or the like.

The alcohol to be used as the polyvalent carboxylic acid ester is not particularly limited, and well-known alcohols and phenols can be used. For example, an aliphatic saturated alcohol or an aliphatic unsaturated alcohol having a linear or side chain having 1 to 32 carbon atoms can be preferably used. More preferably, the carbon number is 1 to 20, and the carbon number is preferably 1 to 10. Further, an alicyclic alcohol such as cyclopentanol or cyclohexanone or a derivative thereof, an aromatic alcohol such as benzyl alcohol or cinnamyl alcohol or a derivative thereof can be preferably used.

When a hydroxypolycarboxylic acid is used as the polyvalent carboxylic acid, the alcoholic or phenolic hydroxyl group of the hydroxypolycarboxylic acid can also be esterified using a monocarboxylic acid. 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 linear or side chain having 1 to 32 carbon atoms can be preferably used. More preferably, the carbon number is 1 to 20, and the carbon number is preferably 1 to 10.

Preferred examples of the aliphatic monocarboxylic acid include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanecarboxylic acid, and eleven. Acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, wax acid, twenty Heptaic acid, octadecanoic acid, tridecanoic acid, three An unsaturated fatty acid such as saturated acid such as dodecanoic acid, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linoleic acid or peanut oleic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid or derivatives thereof.

Examples of the preferred aromatic monocarboxylic acid include an alkyl group, a biphenyl carboxylic acid, a naphthalene carboxylic acid, a tetrahydronaphthalene carboxylic acid, and the like introduced into a benzene ring of benzoic acid such as benzoic acid or toluic acid. An aromatic monocarboxylic acid having two or more benzene rings or a derivative thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

The molecular weight of the polycarboxylic acid ester is not particularly limited, but is preferably in the range of from 300 to 1,000, more preferably from 350 to 750. The larger one is preferable in that the retention property is improved, and it is preferably small in terms of moisture permeability and compatibility with cellulose ester.

The alcohol to be used for the polyvalent carboxylic acid ester may be one type or a mixture of two or more types.

The acid value of the polycarboxylic acid ester is preferably 1 mgKOH/g or less, more preferably 0.2 mgKOH/g or less. By setting the acid value to the above range, it is preferable to suppress the environmental change of the hysteresis.

The acid value refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the sample (the carboxyl group present in the sample). The acid value was measured in accordance with JIS K0070.

Examples of particularly preferred polycarboxylate compounds are shown below, but the invention is not limited thereto. For example, triethyl citrate, tributyl citrate, ethoxylated triethyl citrate (ATEC), acetyl citrate Tributyl acrylate (ATBC), benzhydryl citrate tributyl citrate, ethoxylated triphenyl citrate, acetyl citrate tribenzyl ester, dibutyl tartrate, dibutyl butyl tartrate, partial Tributyl trimellitate, tetrabutyl trimellitate, and the like.

<UV absorber>

When the ultraviolet absorbing agent is contained in the second protective film of the present invention, the light transmittance at 380 nm is the most effective means of less than 50%.

The ultraviolet absorber is intended to improve the durability by absorbing ultraviolet rays having a wavelength of 400 nm or less. Particularly, the transmittance at a wavelength of 380 nm is preferably 50% or less, more preferably 25% or less, and still more preferably 10% or less.

The ultraviolet absorber to be used is not particularly limited, and examples thereof include a hydroxydiphenylketone compound, a benzotriazole compound, a salicylate compound, a diphenylketone compound, and a cyanoacrylate compound. A triazine compound, a nickel salt fault compound, an inorganic powder or the like.

As the ultraviolet absorber applicable in the present invention, for example, 5-chloro-2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole, (2-2H-benzene) And triazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, 2-hydroxy-4-benzylhydroxydiphenyl ketone, 2,4-benzylhydroxyl Phenyl ketone or the like, and Tinuvin such as Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc., which are commercially available from BASF Japan Co., Ltd., can be preferably used.

Better use of UV absorbers is benzotriazole UV The line absorber, the diphenyl ketone ultraviolet absorber, and the triazine-based ultraviolet absorber are particularly preferably a benzotriazole-based ultraviolet absorber or a diphenylketone-based ultraviolet absorber.

For example, as the benzotriazole-based ultraviolet absorber, a compound represented by the following formula (b) can be used.

In the above formula (b), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and each represents a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group or an aromatic group. Alkoxy group, alkoxy group, decyloxy group, aryloxy group, alkylthio group, arylthio group, mono or dialkylamino group, mercaptoamine group or 5- to 6-membered heterocyclic group, R ₄ and R _{5 are} also The ring can be closed to form a carbon ring of 5-6 members. Further, the groups described above may have any substituent.

Specific examples of the benzotriazole-based ultraviolet absorber are given below, but the present invention is not limited thereto.

UV-1: 2-(2'-hydroxy-5-methylphenyl)benzotriazole

UV-2: 2-(2'-hydroxy-3,5'-di-t-butylphenyl)benzotriazole

UV-3: 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole

UV-4: 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole

UV-5: 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl)benzo Triazole

UV-6: 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol)

UV-7: 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole

UV-8: 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol (TINUVIN 171)

UV-9: Octyl-3-[3-t-butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl- Mixture of 3-[3-t-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate (TINUVIN 109)

Further, as the diphenylketone-based ultraviolet absorber, a compound represented by the following formula (c) is preferably used.

In the above formula (c), Y represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group or a phenyl group, and such an alkyl group, an alkenyl group and a phenyl group may have a substituent. A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a CO(NH) _n-1 -D group, and D represents an alkyl group, an alkenyl group or a substituent. Base phenyl. m and n represent 1 or 2.

In the above, the alkyl group is, for example, a linear or branched aliphatic group having a carbon number of up to 24, the alkoxy group is, for example, an alkoxy group having a carbon number of up to 18, and the alkenyl group is, for example, an alkenyl group having a carbon number of up to 16, Allyl, 2-butenyl and the like. Further, examples of the substituent for the alkyl group, the alkenyl group and the phenyl group include a halogen atom such as a chlorine atom, a bromine atom or a fluorine atom, a hydroxyl group or a phenyl group (the alkyl group or the halogen atom may be substituted on the phenyl group). and many more.

Specific examples of the diphenylketone-based ultraviolet absorber represented by the general formula (c) are shown below, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxydiphenyl ketone

UV-11: 2,2'-dihydroxy-4-methoxydiphenyl ketone

UV-12: 2-hydroxy-4-methoxy-5-sulfodiphenyl ketone

UV-13: bis(2-methoxy-4-hydroxy-5-benzylidenephenylmethane)

Further, a discotic compound such as a compound having a 1,3,5-triazine ring is preferably used as the ultraviolet absorber.

The second protective film of the present invention may contain two or more kinds of ultraviolet absorbers.

In the present invention, as the ultraviolet absorber, in particular, "2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl group) shown below can be preferably used. )-4-(1,1,3,3-tetramethylbutyl)phenol) (trade name: TINUVIN 928, manufactured by BASF Japan).

The second protective film of the present invention may contain two or more kinds of ultraviolet absorbers.

Further, as the ultraviolet absorber, a polymer ultraviolet absorber can be preferably used, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used.

The ultraviolet absorber may be added by dissolving the ultraviolet absorber in an alcohol such as methanol, ethanol or butanol or a solvent such as dichloromethane, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Into the glue, or directly added to the glue composition. If the inorganic powder is not dissolved in the organic solvent, it may be dispersed in the organic solvent and the cellulose ester using a dissolver or a sand mill, and then added to the dope.

The amount of the ultraviolet absorber to be used varies depending on the type of the ultraviolet absorber, the use conditions, and the like. However, when the dry film thickness of the second protective film is in the range of 10 to 100 μm, 100% by mass relative to the second protective film. It is preferably in the range of 0.5 to 10% by mass, more preferably in the range of 0.6 to 4% by mass.

<Microparticles>

The second protective film may contain fine particles. Examples of the fine particles include inorganic cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, calcium citrate hydrate, and aluminum citrate. Magnesium citrate and calcium phosphate. The microparticles are preferably contained in the turbidity, and are particularly preferably cerium oxide. The fine particles described in the present invention are particles in which the average particle diameter of the primary particles is in the range of 5 to 400 nm.

The average particle diameter of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. These may be mainly contained as a secondary aggregate having a particle diameter of 0.05 to 0.3 μm, and if the particles having an average particle diameter of 100 to 400 nm do not aggregate, they are preferably contained as primary particles. The content of such fine particles in the second protective film is preferably in the range of 0.01 to 1% by mass, particularly preferably in the range of 0.05 to 0.5% by mass. In the case of the second protective film composed of a plurality of layers by the co-casting method, it is preferred to contain the added amount of fine particles on the surface.

The fine particles of cerium oxide are commercially available, for example, under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.).

The fine particles of zirconia are commercially available, for example, under the trade names of Aerosil R976 and R811 (above, manufactured by Nippon Aerosil Co., Ltd.).

Examples of the polymer include polyfluorene oxide resin and fluorine tree. Grease and acrylic resin. Preferably, it is a polyoxyxylene resin, particularly preferably a three-dimensional network structure, for example, Tosperal 103, the same 105, the same 108, the same 120, the same 145, the same 3120, and the same 240 (above, Toshiba polyoxyl ( The product name of the stock system is commercially available and can be used.

Among these, it is particularly preferable to use Aerosil 200V and Aerosil R972V because the effect of lowering the friction coefficient while keeping the turbidity of the second protective film low is large. In the second protective film of the present invention, the dynamic friction coefficient of at least one surface is preferably in the range of 0.2 to 1.0.

Various additives may be added in portions as a slurry of a cellulose ester-containing solution before film formation, or an additive solution may be additionally prepared and added in-line. In particular, in order to reduce the load of the fine particles on the filter material, it is preferred to add a part or the whole amount in the line.

When the additive solution is added to the line, it is preferred to dissolve a small amount of the cellulose ester in order to improve the miscibility with the dope. The amount of the cellulose ester is preferably in the range of 1 to 10 parts by mass, more preferably 3 to 5 parts by mass, per 100 parts by mass of the solvent.

In the present embodiment, in order to perform in-line addition and mixing, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering Co., Ltd.) or a SWJ (Toray static in-line mixer Hi-Mixer) or the like is preferably used.

(Method for producing cellulose resin film)

Next, a method of producing a cellulose resin film as an example of the second protective film will be described.

The cellulose resin film can be produced by a solution casting method. The film may be a film produced by a melt casting method, and any of them may be preferably used, but a film produced by a solution casting method is particularly preferred.

The film produced by the solution casting method is produced by the steps of dissolving the cellulose ester and the additive in a solvent to prepare a dope, and casting the ring-shaped metal support in which the dope is infinitely moved. a step of making the casted paste into a web, performing a drying step, a step of peeling from the metal support, a step of stretching or maintaining the width, and a step of further drying, and winding the finished film .

The step of modulating the preparation of the glue is explained. The concentration of the cellulose ester in the dope is preferably such that the drying load after casting on the metal support is reduced, but if the concentration of the cellulose ester is too rich, the load at the time of filtration is increased, and the filtration accuracy is deteriorated. In order to achieve such a concentration, it is preferably in the range of 10 to 35 mass%, more preferably 15 to 25 mass%.

The solvent used for the dope may be used singly or in combination of two or more. However, it is preferred to use a good solvent and a weak solvent for the mixed cellulose ester, and the user is more suitable for the production efficiency. The solubility point is preferred. A preferred range of the mixing ratio of the good solvent to the weak solvent is in the range of 70 to 98% by mass in the good solvent and 2 to 30% by mass in the weak solvent. The so-called good solvent and weak solvent are those in which the cellulose ester used alone is dissolved as a good solvent, and those which are swollen or insoluble alone are defined as a weak solvent. Therefore, depending on the average degree of acetylation of the cellulose ester (the degree of substitution of the ethyl thiol group), the good solvent and the weak solvent change, for example, when acetone is used as the solvent, the acetate in the cellulose ester (the degree of substitution of the ethyl ketone is 2.4). ), cellulose B The acid propionate becomes a good solvent and becomes a weak solvent in the cellulose acetate (the degree of substitution of acetyl group 2.8).

The good solvent to be used is not particularly limited, and examples thereof include an organic halogen compound such as dichloromethane, dioxolane, acetone, methyl acetate, methyl ethyl acetate or the like. Particularly preferred is dichloromethane or methyl acetate.

Further, the weak solvent to be used is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone or the like is preferably used. Further, it is preferred to contain 0.01 to 2% by mass of water in the dope. Further, the solvent used for the dissolution of the cellulose ester is removed from the film by drying in the film forming step, and the solvent is recovered and reused. The recovered solvent may also contain a trace amount of an additive added to the cellulose ester, such as a plasticizer, a UV absorber, a polymer, a monomer component, etc., but even if it is contained, it can be preferably reused. If necessary, it can be purified and reused.

When the above-described dope is prepared, a general method can be used as a method of dissolving the cellulose ester. When combined with heating and pressurization, it can be heated to a boiling point or higher at normal pressure. When the solvent is at a pressure higher than the boiling point of the solvent and pressurized, and the mixture is stirred and dissolved while heating at a temperature in which the solvent does not boil, the occurrence of a blocky undissolved substance called a gel or a powder group can be prevented. More suitable. Further, it is also preferred to use a method in which a cellulose ester is mixed with a weak solvent to wet or swell, and then a good solvent is added and dissolved.

The pressurization system can be carried out by a method of injecting an inert gas such as nitrogen or by a method of increasing the vapor pressure of the solvent by heating. The heating is preferably carried out from the outside, and for example, the jacket type is easy to control the temperature.

The heating temperature at which the solvent is added is preferably from the viewpoint of solubility of the cellulose ester. However, if the heating temperature is too high, the pressure required is increased and the productivity is deteriorated. The preferred heating temperature is in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and particularly preferably in the range of 70 to 105 ° C. Further, the pressure is adjusted so that the solvent does not boil at the set temperature.

Further, it is also preferred to use a cooling dissolution method whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

Next, the cellulose ester solution is filtered using a suitable filter material such as filter paper. As the filter material, in order to remove insoluble matter or the like, the absolute filtration accuracy is preferably as small as possible. However, if the absolute filtration accuracy is too small, there is a problem that clogging of the filter material is likely to occur. Therefore, it is preferable that the filter material having an absolute filtration accuracy of 0.008 mm or less is more preferably a filter material having an absolute filtration accuracy of 0.001 to 0.008 mm, and particularly preferably a filter having an absolute filtration accuracy of 0.003 to 0.006 mm. material.

The material of the filter material is not particularly limited, and a general filter material may be used, and a plastic filter material such as polypropylene or Teflon (registered trademark) or a metal filter material such as stainless steel may not fall off. It is preferred to remove and reduce impurities contained in the cellulose ester of the raw material, particularly bright foreign matter, by filtration.

In the case of a bright spot foreign matter, two polarizing plates are placed in a crossed Nicols state, and a second protective film is placed therebetween, and light is irradiated from one side of the polarizing plate to the side of the other polarizing plate. When observing, the point of leakage of light from the opposite side (foreign matter) is seen, and the number of bright spots 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, and particularly preferably 50 pieces. Below /cm ² , it is more preferably in the range of 0 to 10 / cm ² . Moreover, the fewer the bright spots having a diameter of 0.01 mm or less, the better.

The filtration system of the dope can be carried out by a usual method, but the method of filtering under heating at a temperature higher than the boiling point of the solvent under normal pressure and at a temperature in which the solvent does not boil is the difference between the filtration pressure before and after the filtration. The rise (called differential pressure) is small and appropriate. The preferred temperature is in the range of 45 to 120 ° C, more preferably in the range of 45 to 70 ° C, and particularly preferably in the range of 45 to 55 ° C.

The smaller the filter pressure, the better. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and particularly preferably 1.0 MPa or less.

Here, the casting of the dope is explained. The metal support in the casting (casting) step is preferably a mirror-finished surface. As the metal support, it is preferred to use a stainless steel strip or a cast and a plated surface. The width of the casting can be set to 1~4m.

The surface temperature of the metal support in the casting step is in the range of -50 ° C to the temperature of the boiling point of the solvent. The higher the temperature, the faster the drying speed of the web can be, but if it is too high, there is a mesh. Foaming or flatness deterioration. The preferred support temperature is in the range of 0 to 40 ° C, more preferably in the range of 5 to 30 ° C. Further, it is also preferred to gel the web by cooling and peel it off from the roll in a state in which a residual solvent is contained.

The method of controlling the temperature of the metal support is not particularly limited, but there is a method of blowing warm air or cold air or a method of bringing warm water into contact with the back side of the metal support. The use of warm water due to efficient heat transfer Preferably, the time until the temperature of the metal support is fixed is short. When using warm air, there is a case where a wind having a higher temperature than the target temperature is used.

In order to exhibit good planarity of the protective film, the amount of residual solvent when the mesh is peeled off from the metal support is preferably in the range of 10 to 150% by mass, more preferably 10 to 40% by mass or 60 to 130% by mass. It is particularly preferably in the range of 10 to 30% by mass or 70 to 120% by mass. Here, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(M - N) / N} × 100

Further, the M system collects the mass of the sample taken from the web or the film at any point during or after the production, and the mass of the mass M is heated at 115 ° C for 1 hour.

Further, in the drying step of the cellulose resin film, the mesh sheet is preferably peeled off from the metal support, and further dried to have a residual solvent amount of 1% by mass or less, more preferably 0.1% by mass or less, particularly preferably 0 to 0.01. Within the range of mass %.

In the film drying step, a roll drying method (a method in which a plurality of rolls are disposed between the upper and lower rolls to alternately pass the web and dried) or a method of drying the net while carrying the web is carried out.

In order to produce a cellulose resin film, it is particularly preferable to stretch in the conveyance direction (longitudinal direction) when the amount of residual solvent in the mesh is large after peeling from the metal support, and to grasp both ends of the mesh by a clip or the like. The tentering method is extended in the tenter direction (lateral direction).

In order to extend in the longitudinal direction immediately after peeling, it is preferred to The peeling tension of 210 N/m or more is peeled off, and particularly preferably in the range of 220 to 300 N/m.

The means for drying the web is not particularly limited, and it can be generally carried out by hot air, infrared rays, heating rolls, microwaves, etc., but it is preferably carried out by hot air at the point of simplicity.

The drying temperature of the drying step of the mesh sheet is preferably increased stepwise in the range of 40 to 200 ° C, and it is preferably carried out in the range of 50 to 140 ° C due to good dimensional stability.

The film thickness of the cellulose resin film is not particularly limited, and can be used in the range of 10 to 200 μm. In particular, the film thickness is preferably in the range of 10 to 60 μm, more preferably in the range of 10 to 40 μm.

The cellulose resin film is used in a range of 1 to 4 m in width. It is particularly preferable to use a range of 1.4 to 4 m in width, and particularly preferably in the range of 1.6 to 3 m. If it exceeds 4 m, handling becomes difficult.

<Extension operation, refractive index control>

In the cellulose resin film which is the second protective film of the present invention, the hysteresis value Ro represented by the following formula (i) is in the range of 40 to 300 nm, and the Rt represented by the formula (ii) is 100. Within the range of ~400nm.

Formula (i): (i) Ro = (n _{x -} n _y ) × d

Formula (ii): Rt = ((n _x + n _y ) / 2 - n _z ) × d

In order to obtain the hysteresis values Ro and Rt of the above-specified range, it is preferable that the second protective film adopts the constitution of the present invention, and the refractive index is further performed by the stretching operation. control.

For example, it may extend sequentially or simultaneously with respect to the longitudinal direction of the film (film forming direction) and the direction orthogonal to the film surface, that is, the width direction.

The stretching ratio in the two-axis direction orthogonal to each other is preferably 0.8 to 1.5 times in the casting direction and 0.8 to 2.0 times in the width direction, and preferably in the casting direction. 0.8 to 1.2 times, in the width direction of 1.1 to 1.5 times.

The method of extending the mesh is not particularly limited. For example, a method of giving a peripheral speed difference to a plurality of rolls and extending in the longitudinal direction by a difference in circumferential speed of the rolls may be used, and the ends of the mesh are fixed by clips or needles to enlarge the interval of the clips or the needles in the traveling direction. The method of extending in the longitudinal direction is similarly a method of expanding in the lateral direction and extending in the lateral direction, or a method of simultaneously expanding in the longitudinal and lateral directions and extending in both the longitudinal and lateral directions. Of course, these methods can also be used in combination, and in the case of the so-called tenter method, if the clip portion is driven by the linear driving method, it is possible to smoothly extend and reduce the risk of breakage or the like.

The width of the film forming step is maintained or laterally extended, preferably by a tenter, and may be a pin tenter or a clip tenter.

The retardation axis or the phase advancement axis of the protective film is present in the film surface, and if the angle formed by the film formation direction is θ1, θ1 is preferably -1° or more and +1° or less, more preferably -0.5. °+0.5° or less. This θ1 can be defined as an alignment angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Θ1 respectively satisfies the above relationship High brightness in the display image can help suppress or prevent light leakage, which can contribute to faithful color reproduction in a color liquid crystal display device.

Further, a specific procedure of a more detailed solution casting method will be described in combination with a method for producing a cycloolefin film containing a cycloolefin resin, which will be described later, using FIG.

[cycloolefin film]

A preferred other aspect of the second protective film of the present invention is a cycloolefin film containing a cycloolefin resin.

In general, the cycloolefin resin is a hydrophobic resin, and it is easy to separate if it has moisture when it is thinned, and it is not preferable from the viewpoint of transparency. However, the cycloolefin resin used in the present invention preferably contains at least one. The hydrogen bond accepting group is formed of a resin composition, and since it can form a hydrogen bond with a hydroxyl group of an alcohol or a hydroxyl group of a hindered phenol type compound, transparency can be maintained even in a state containing a large amount of water, and instead, hydrogen bonding can be maintained. The feature of increased film strength. The "hydrogen bond accepting group" means a functional group capable of accepting a hydrogen atom when a hydrogen bond is formed.

The cycloolefin resin of the present invention is characterized in that it is formed of a resin composition containing at least one hydrogen bond accepting group.

Examples of the hydrogen bond accepting group include an alkoxy group having 1 to 10 carbon atoms, a decyloxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, and an aryloxycarbonyl group. a cyano group, a decylamino group, a quinone ring containing a triammonium group, a triorganomethoxy group, a triorganosilyl group, a fluorenyl group, an alkoxyalkyl group having 1 to 10 carbon atoms, a sulfonyl group and a carboxyl group; Wait. For this When the polar group is more specifically described, examples of the alkoxy group include a methoxy group and an ethoxy group; and examples of the decyloxy group include an ethoxy group, a propyloxy group, and the like. An arylcarbonyloxy group such as an alkylcarbonyloxy group or a benzamidineoxy group; and examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; and examples of the aryloxycarbonyl group include an aryloxycarbonyl group. a phenoxycarbonyl group, a naphthyloxycarbonyl group, a decyloxycarbonyl group, a biphenyloxycarbonyl group, etc., and examples of the triorganomethoxy group include a trimethyldecyloxy group and a triethylphosphoniumoxy group; Examples of the triorganoalkylene group include a trimethylsulfanyl group and a triethylsulfanyl group; and examples of the alkoxyalkylene group include a trimethoxydecyl group and a triethoxydecyl group.

The amount of the cycloolefin-based resin containing the hydrogen bond-receiving group contained in the resin component is not particularly limited, but the content ratio is preferably in the range of 10 to 100% by mass. When it is 10 mass% or more, it is preferable that the obtained ring-opening copolymer becomes soluble in a solvent such as toluene or dichloromethane, and further, from the viewpoint of solubility, film strength, and transparency. Look, it is better in the range of 30 to 100% by mass.

The cycloolefin resin of the present invention is, for example, a (co)polymer represented by the following formula (I).

In the above formula (I), p is 0 or 1, and m is an integer of 0 or more. R ¹ to R ⁴ each independently represent a hydrogen atom, a hydrocarbon group, a halogen atom or a hydrogen bond accepting group. Further, R ¹ to R ⁴ may be bonded to each other to form an unsaturated bond, a monocyclic ring or a polycyclic ring, and the monocyclic or polycyclic ring system may have a double bond and also form an aromatic ring.

In the present invention, the ratio of the preferred hydrogen bond accepting group of the cycloolefin resin is preferably one or two of R ¹ to R ⁴ in the above formula (I), and preferably has a hydrogen bond accepting group.

Further, the retention ratio of the hydrogen bond accepting group of the cycloolefin resin can be identified, for example, by carbon-13 nuclear magnetic resonance ( ¹³ C-NMR) spectroscopy.

Further, in the formula (I), R ¹ and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 4 or more preferably 1 to 2, and at least one of R ² and R ⁴ is hydrogen. The polar hydrogen bond accepting group other than the atom and the hydrocarbon group and p and m are m=1 and p=0 are preferable from the viewpoint that the glass transition temperature is high and the mechanical strength is excellent.

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group such as a methyl group, an ethyl group or a propyl group; a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group; and an alkene such as a vinyl group, an aryl group or a propylene group. An aromatic group such as a phenyl group, a biphenyl group, a naphthyl group or a fluorenyl group. The hydrocarbon group may be substituted, and examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom, and a phenylsulfonyl group.

The preferred molecular weight of the cycloolefin resin of the present invention is preferably 0.2 to 5 cm ³ /g, more preferably 0.3 to 3 cm ³ /g, and particularly preferably 0.4 to 1.5 cm ³ /g, in terms of intrinsic viscosity [η]inh. The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is preferably 8,000 to 100,000, more preferably 10,000 to 80,000, particularly preferably 12,000 to 50,000, and a weight average molecular weight (Mw). It should be 20,000 to 300,000, more preferably 30,000 to 250,000, and particularly preferably in the range of 40,000 to 200,000.

The intrinsic viscosity [η]inh, the number average molecular weight, and the weight average molecular weight are in the above range, and the heat resistance, water resistance, chemical resistance, and mechanical properties of the cycloolefin resin and the formability of the cycloolefin resin film of the present invention are changed. good.

The glass transition temperature (Tg) of the cycloolefin resin of the present invention is usually 110 ° C or higher, preferably 110 to 350 ° C, more preferably 120 to 250 ° C, and particularly preferably 120 to 220. Within the range of °C. When Tg is 110 ° C or more, it is preferable to suppress deformation due to use under high temperature conditions or secondary processing such as coating or printing. Further, when the Tg is 350 ° C or lower, it is preferable to suppress degradation of the resin due to heat during molding or molding.

The cycloolefin-based resin described above can be preferably used as a commercial product, and is sold as a commercial product by JSR (share) under the trade names of Arton G, Atong F, Atong R, and Atong RX. , you can use this.

(Additive for cycloolefin film)

<Vermiculite particles>

In the cycloolefin film of the present invention, in order to process the film produced At the same time, when the second protective film is used for the protective film of the polarizing plate, the second protective film in which the crack or the chip is reduced during the pressing of the polarizing plate is obtained, and it is preferable to contain the specific protective film. Hydrophobicity of vermiculite particles.

The vermiculite particle of the present invention is a degree of hydrophobicity measured by a methanol wettable method, and the degree of hydrophobicity is 20% or less when a first solution having a volume ratio of methanol to pure water of 3:7 is used, and methanol is used. The degree of hydrophobization of the second solution having a volume ratio of 6:4 to pure water is 80% or more of vermiculite particles. The degree of hydrophobization is measured by the aforementioned MW method.

The so-called meteorite particles are particles containing cerium oxide as a main component. The main component is preferably 50% or more of the components constituting the particles, preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.

In addition, when the particles of the cerium oxide-based particles and the hydrophobized microparticles having an alkylation treatment are added, the dispersibility in the solvent is good, and the occurrence of foreign matter can be suppressed.

The above hydrophobization treatment of the vermiculite particles is preferably an alkylation treatment. The surface of the alkylated microparticles has an alkyl group, and the carbon number of the alkyl group is preferably in the range of 1 to 20, more preferably in the range of 1 to 12 carbon atoms, particularly preferably in the range of 1 to 8 carbon atoms. .

Among the above-mentioned vermiculite particles, those having an alkyl group having a carbon number of 1 to 20 on the surface can be obtained, for example, by treating the above-mentioned particles of cerium oxide with octyldecane. In addition, as an example of an octyl group on the surface, it is commercially available under the trade name of Aerosil R805 (made by Japan Aerosil Co., Ltd.). Should be used.

The average particle diameter of the primary particles of the vermiculite particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm.

The average particle diameter of the secondary particles of the vermiculite particles is preferably in the range of 100 to 400 nm. However, as long as the average particle diameter of the primary particles is in the range of 100 to 400 nm, it is not aggregated, and it is preferably contained as primary particles.

<hindered phenolic compounds>

The phenolic compound is a known compound, and is contained, for example, in the columns 12 to 14 of the specification of U.S. Patent No. 4,839,405, and contains a 2,6-dialkylphenol derivative compound. As a preferable compound among such compounds, a compound represented by the following formula (II) is preferred.

In the above formula (II), R ₅₁ to R ₅₆ represent a hydrogen atom or a substituent. Examples of the substituent include a halogen atom (for example, a fluorine atom or a chlorine atom) and an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, or a trifluoromethyl group). a third butyl group or the like, a cycloalkyl group (for example, a cyclopentyl group, a cyclohexyl group, etc.), an aralkyl group (for example, a benzyl group, a 2-phenylethyl group, etc.), an aryl group (for example, a phenyl group, a naphthyl group, P-tolyl, p-chlorophenyl, etc.), alkoxy (eg, methoxy, ethoxy, isopropoxy, butoxy, etc.), aryloxy (eg, phenoxy, etc.), cyano a mercaptoamine group (for example, an ethenylamino group, a propylamino group, etc.), an alkylthio group (for example, a methylthio group, an ethylthio group, a butylthio group, etc.), an arylthio group (for example, a benzene sulfide) a sulfonylamino group (for example, a methanesulfonylamino group, a benzenesulfonylamino group, etc.), a urea group (for example, a 3-methylureido group, a 3,3-dimethylureido group, 1,3-dimethylureido or the like), amidoximeylamino group (dimethylaminesulfonylamino group, etc.), amine methyl sulfhydryl group (for example, methylamine carbaryl, ethylamine formazan) Base, dimethylamine, mercapto group, etc.), amidoxime (for example, ethylamine sulfonyl, dimethylamine sulfonyl, etc.), alkoxy a carbonyl group (for example, a methoxycarbonyl group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (for example, a phenoxycarbonyl group, etc.), a sulfonyl group (for example, a methylsulfonyl group, a sulfonyl group, a phenylsulfonyl group). Base, etc., fluorenyl (eg, ethyl, propyl, butyl, etc.), amine (methylamino, ethylamino, dimethylamino, etc.), cyano, hydroxy, nitro, Nitroso, amine oxide groups (eg, pyridine-oxide groups), quinone imine groups (eg, xylylene imino groups, etc.), disulfide groups (eg, benzene disulfide groups, benzo Thiazole-2-disulfide group, etc., carboxyl group, sulfo group, heterocyclic group (for example, pyrrolyl, pyrrolidinyl, pyrazolyl, imidazolyl, pyridyl, benzimidazolyl, benzothiazolyl, benzene And oxazolyl, etc.). These substituents may also be substituted.

Further, a phenol compound in which R ₅₁ is a hydrogen atom, R ₅₂ and R ₅₆ are a third butyl group is preferred.

The hindered phenol compound of the present invention is not particularly limited, and specific examples thereof are exemplified.

Specific examples of the compound include n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, n-octadecyl 3-(3,5-di Third butyl-4-hydroxyphenyl)-acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl- 4-hydroxyphenyl benzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenyl benzoate, neododeto-3-(3,5-di-t-butyl 4-hydroxyphenyl)propionate, dodecyl β(3,5-di-t-butyl-4-hydroxyphenyl)propionate, ethyl α-(4-hydroxy-3,5-di Third butyl phenyl) isobutyrate, octadecyl α-(4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α-(4-hydroxy-3 ,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(n-octylthio)ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio)ethyl 3,5-di-t-butyl-4-hydroxy-phenyl acetate, 2-(n-octadecylthio)ethyl 3,5-di-t-butyl- 4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2-(2-hydroxyethylthio) Ethyl 3,5-di-t-butyl-4-hydroxybenzoic acid Ester, diethyl diol bis-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate, 2-(n-octadecylthio)ethyl 3-(3,5- Di-tert-butyl-4-hydroxyphenyl)propionate, stearylamine N,N-bis-[extended ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propane Acid ester], n-butylimido N,N-bis-[stretch ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2-(2-hard Lipidoxyethylthio)ethyl 3,5-di-t-butyl-4-hydroxybenzoate, 2-(2-stearyloxyethylthio)ethyl 7-(3-methyl 5--5-butyl-4-hydroxyphenyl)heptanoate, 1,2-propanediol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] , ethylene glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], neopentyl glycol bis-[3-(3,5-di-t-butyl) -4-hydroxyphenyl) propyl Acid ester], ethylene glycol bis-(3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerol-1-n-octadecanoate-2,3-bis-(3,5 -di-tert-butyl-4-hydroxyphenylacetate), pentaerythritol-tetrakis-[3-(3',5'-di-t-butylt-4'-hydroxyphenyl)propionate], 1 , 1,1-trimethylolethane-tris-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], sorbitol hexa-[3-(3,5 -di-t-butyl-4-hydroxyphenyl)propionate], 2-hydroxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate, 2-hard Lipidoxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 1,6-n-hexanediol-bis[(3',5'-di Tributyl-4-hydroxyphenyl)propionate], pentaerythritol-tetrakis(3,5-di-t-butyl-4-hydroxyhydrocinnamate), and the like.

As a specific example of the hindered phenol-based antioxidant which is useful, the following exemplified compounds are shown, but are not limited thereto.

Further, the phenol compound of the above type is commercially available, for example, under the trade names of "Irganox 1035", "Irganox 1076" and "Irganox 1010" by BASF Japan Co., Ltd.

The amount of the phenolic compound to be added is suitably designed in terms of 100 parts by mass of the cycloolefin resin, but is preferably in the range of 0.1 to 1.0 part by mass, more preferably 0.3 to 0.5 part by mass.

<Other additives>

As the other additive, the polyester compound, the polyol ester compound, the polyvalent carboxylate compound (including the phthalate compound), the glycolate compound, and the ester compound described in the cellulose resin film can be similarly used (including A fatty acid ester compound or a phosphate compound, etc., an ultraviolet absorber, or the like.

[Manufacturing method of cycloolefin film]

The method for producing a cycloolefin film as the second protective film of the present invention may be a solution casting film forming method or a melt casting film forming method, but it is preferably produced by a solution casting film forming method.

(solution casting film forming method)

The cycloolefin film of the present invention is formed by a solution casting film forming method, and it is preferred to prepare a cycloolefin resin having at least one hydrogen bond accepting group at a dissolution temperature of 15 to 50 ° C. a vermiculite particle satisfying the hydrophobization degree, the hindered phenol-based compound, and an alcohol-containing solvent The glue of the organic solvent.

When the dissolution temperature is 15° C. or more, the resin or the additive can be sufficiently dissolved to obtain a film having a small amount of foreign matter. Further, at 50 ° C or lower, it is preferable from the viewpoint of suppressing the coloration of the dope and the obtained film caused by the reaction between the alcohol and the hindered phenol compound, and also adding the vermiculite particles having good affinity with the alcohol. Suppress the effect of coloring.

The second protective film of the present invention is preferably produced by the step of preparing a dope containing at least a cycloolefin-based resin, vermiculite particles, a hindered phenol-based compound, and an organic solvent containing an alcohol solvent (seed preparation) a step of casting the above-mentioned dope on a support to form a mesh (also referred to as a cast film) (casting step), evaporating the solvent from the mesh on the support (solvent evaporation step), a step of peeling the mesh from the support (peeling step), a step of drying the obtained film (pre-drying step), a step of stretching the film (extension step), and a step of drying the stretched film (drying step), roll The step of taking the obtained second protective film (winding step).

Use the diagram to illustrate the above steps.

Fig. 2 is a view schematically showing an example of a dope preparation step, a casting step, a drying step, and a winding step of a preferred solution casting film forming method in the present invention. The solution casting film forming method shown in Fig. 2 can also be applied to the above-described method for producing a cellulose resin film.

The fine particle dispersion in which the solvent and the vermiculite particles of the present invention are dispersed via a disperser is stored in the storage tank (42) through the filter (44) from the feed tank (41). On the other hand, the cycloolefin resin as the main dope is dissolved in the dissolution vessel (1) together with the solvent, and is preferably added to the storage vessel (42). The stored fine particle dispersion is added and mixed to form a main dope. The obtained main glue is filtered from the filter (3) and the storage tank (4) by a filter (6), and the additive is added by the mixing tube (20), and mixed in the mixer (21) to supply liquid to the mixture. Pressurizing die (30).

On the other hand, the additive (the hindered phenol compound of the present invention, or the ultraviolet absorber, the phase difference increasing agent, etc.) is dissolved in a solvent, and is stored in the storage from the additive feed tank (10) through the filter (12). Inside the kettle (13). Then, it is mixed with the main dope through a filter (15) via a conduit (16) by a confluent tube (20) and a mixer (21).

The main dope sent to the press die (30) is cast on a metal strip-shaped support (31) to form a mesh (32), which is peeled off at the peeling position (33) after the specified drying. film. The peeled web (32) is dried by a plurality of conveyance rolls to a predetermined amount of residual solvent, and then extended in the longitudinal direction or the width direction by the stretching device (34). After being extended, the drying device (35) is used to form a predetermined amount of residual solvent, and is dried by a conveyance roller (36), and is wound into a roll shape by a winding device (37).

Hereinafter, each step will be described.

(1) Glue preparation step

In the organic solvent mainly containing a good solvent for the cycloolefin resin, the cycloolefin resin, the hindered phenol compound, the phase difference increasing agent, the vermiculite particles, or other compounds are stirred in the dissolution vessel. a step of preparing a dope while dissolving, or in the cycloolefin resin solution, The step of preparing the dope as the main solution is carried out by mixing the hindered phenol compound, optionally the phase difference increasing agent, vermiculite particles or other compound solution.

When the second protective film of the present invention is produced by a solution casting method, it is preferred that the organic solvent for forming the dope dissolves the cycloolefin resin, the hindered phenol compound, or the phase difference increasing agent and other compounds.

As the organic solvent to be used, the following solvents are preferably used.

Examples of the solvent used in the solution casting method include a chlorine-based solvent such as chloroform or dichloromethane; an aromatic solvent such as toluene, xylene, benzene or a mixed solvent thereof; methanol, ethanol, or isopropanol. An alcohol solvent such as n-butanol or 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl hydrazine, dioxane, cyclohexane Ketone, tetrahydrofuran, acetone, methyl ethyl ketone (abbreviation: MEK), ethyl acetate, diethyl ether, and the like. These solvents may be used alone or in combination of two or more.

When the solvent of the present invention is a mixed solvent of a good solvent and a weak solvent, the good solvent is, for example, a chlorine-based organic solvent, and the non-chlorine-based organic solvent is methyl acetate or acetic acid. Ethyl ester, amyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoro Ethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl- 2 propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol, ethanol , n-propanol, isopropanol, n-butyl An alcohol, a second butanol, a third butanol or the like, of which dichloromethane is preferred.

The weak solvent is an alcohol-based solvent of the present invention, and it is necessary to exhibit the effects of the present invention in the range of 10 to 1000 ppm in the first protective film.

The content of the above alcohol-based solvent contained in the cycloolefin film of the present invention is the amount of the residual solvent, and refers to the content contained in the film after the film is produced. The amount of the solvent can be quantified by the headspace gas chromatography described later, but the measurement is a value measured during the period from the production of the film to the time before the film processing. Usually, after the film is produced and wound up, it is covered with a protective sheet or the like and stored in a quasi-closed state. Since this state is before the processing, the amount of residual solvent is small. Therefore, the measurement of the amount of residual solvent is taken from the value measured during the period from the production of the film to the time before the film processing, and it is judged whether or not the composition of the present invention is the same.

The control of the amount of residual solvent can be carried out by drying conditions such as the composition ratio of the solvent, the drying temperature in the film formation, the drying time, the film thickness, and the like.

The content of the alcohol solvent remaining in the cycloolefin film of the present invention is preferably in the range of 10 to 500 ppm, more preferably in the range of 20 to 200 ppm. The effect of the present invention is exhibited at 10 ppm or more, and the peeling property from the metal support in the solution casting film formation is also improved. Below 1000 ppm is preferred from the viewpoint of haze and environmental safety.

The alcohol-based solvent of the present invention is selected from the group consisting of methanol, ethanol and butanol, and is preferable from the viewpoint of the effect of the present invention and at the same time improving the peeling property and allowing high-speed casting. Among them, from the above viewpoint, ethanol is preferred.

In the present invention, it is preferred to use the above-mentioned good solvent in an amount of 55 mass% or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total amount of the solvent.

Further, from the viewpoint of improvement in productivity, the cycloolefin film of the present invention is preferably used by combining an alcohol solvent having a hydroxyl group and water, and it is preferred to add water to the above-mentioned dope to be in the range of 5 to 5000 ppm. The film contains water as a residual solvent amount.

Since water has a plurality of hydrogen bond donor groups in one molecule, it is preferably used in order to increase the strength of the film. The water is preferably contained in an amount of 0.1 to 1% by mass based on the total amount of the solvent of the present invention. When it is 0.1% by mass or more, it is preferable to easily interact with other alcohol-based solvents or a cycloolefin-based resin or a vermiculite particle containing a hydrogen bond-receiving group, and if it is within 1% by mass, hydrophobicity can be suppressed. The gelation of a strong cycloolefin resin inhibits the occurrence of foreign matter.

<Residual solvent amount>

The residual amount of the above-mentioned alcohol and water used as a solvent component in the film is carried out by the following measurement method.

The cut into a shape of the film was placed in a 20 mL sealed glass container, and treated at 120 ° C for 20 minutes, after gas chromatography (machine: HP 5890 SERIES II, column: J & W DB-WAX (inner diameter) 0.32 mm, length 30 m), detection: FID), and the GC temperature rising condition was obtained by holding at 40 ° C for 5 minutes and then raising the temperature to 100 ° C at 80 ° C / minute.

In the dissolution of the cycloolefin-based resin, the hindered phenol-based compound, and other compounds, a method of performing at normal pressure, a method of performing at a boiling point or lower of the main solvent, or a method of pressurizing at a boiling point or higher of the main solvent may be used. A method of performing a cooling and dissolving method as described in Japanese Laid-Open Patent Publication No. Hei 9-95537, No. 9-95557, or Japanese Laid-Open Patent Publication No. Hei 9-95538 Various methods of dissolving such as a method carried out under high pressure are preferably carried out in the range of 0.8 to 4.0 MPa from the viewpoint of solubility.

The concentration of the cycloolefin resin in the dope is preferably in the range of 10 to 40% by mass. The compound is added to the dope during or after dissolution, dissolved and dispersed, filtered through a filter medium, defoamed, and pumped to the next step by liquid feeding.

Regarding the filtration of the dope, it is preferable to filter the dope with a main filter 3 having a leaf disc type filter, for example, 90% of a filter medium having a particle diameter within a range of 10 to 100 times the average particle diameter of the fine particles. .

In the present invention, the filter medium used for filtration is preferably as small as the absolute filtration accuracy. However, if the absolute filtration accuracy is too small, clogging of the filter material tends to occur, and the exchange of the filter material must be frequently performed, which may reduce the productivity.

Therefore, in the present invention, the filter medium for the rubber containing the cycloolefin resin preferably has an absolute filtration accuracy of 0.008 mm or less, and the absolute filtration accuracy is preferably in the range of 0.001 to 0.008 mm, and the absolute filtration accuracy is 0.003. Filter media in the range of ~0.006mm is especially preferred.

The material of the filter material is not particularly limited and can be used normally. The filter medium, the plastic filter material such as polypropylene, Teflon (registered trademark), or the metal filter material such as stainless steel fiber is preferably not dropped.

In the present invention, the flow rate of the dope at the time of filtration is preferably in the range of 10 to 80 kg / (h ‧ m ² ), more preferably in the range of 20 to 60 kg / (h ‧ m ² ). Here, when the flow rate of the dope at the time of filtration is 10 kg / (h ‧ m ² ) or more, productivity becomes efficient, and if the flow rate of the dope at the time of filtration is 80 kg / (h ‧ m ² ), The pressure applied to the filter medium is appropriate, and it is preferred that the filter material is not damaged.

The filtration pressure is preferably 3,500 kPa or less, more preferably 3,000 kPa or less, and particularly preferably 2,500 kPa or less. Furthermore, the filtration system can be controlled by suitably selecting the filtration flow rate and the filtration area.

In most cases, the main glue contains about 1 to 50% by mass of a return material.

The material to be recycled is, for example, a finely pulverized material of a cycloolefin film, a side portion of the film which is formed when the cycloolefin film is formed, or a cycloolefin film which exceeds a predetermined value of the film due to abrasion or the like. Raw material.

Moreover, as a raw material of the resin used for the preparation of the dope, it is preferable to use a cycloolefin-based resin, other compounds, or the like in advance.

(2) Casting step

(2.1) Casting of the glue

A circulating metal support (31) in which the glue is fed to the pressurizing die (30) by a liquid feeding pump (for example, a pressurized quantitative gear pump) and moved indefinitely The casting position on the metal support such as a stainless steel belt or a rotating metal drum, the step of casting the glue from the slit of the press die.

The metal support in the casting (casting) step is preferably a mirror-finished surface. As the metal support, it is preferred to use a stainless steel strip or a cast and a plated surface. The width of the casting may be in the range of 1 to 4 m, preferably in the range of 1.3 to 3 m, more preferably in the range of 1.5 to 2.8 m. The surface temperature of the metal support in the casting step is -50 ° C - the temperature at which the solvent is not boiling and foaming, and more preferably in the range of -30 to 0 ° C. The higher the temperature, the faster the drying speed of the mesh (casting the glue on the metal support for casting, and the formed glue film is called the mesh), but if it is too high, there is a mesh The case where the flatness is deteriorated by foaming or the like. The preferred support temperature is suitably determined in the range of 0 to 100 ° C, more preferably in the range of 5 to 30 ° C. Alternatively, it is also preferred to gel the web by cooling and peel it off from the roll in a state containing a large amount of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there is a method of blowing warm air or cold air or a method of bringing warm water into contact with the back side of the metal support. It is preferable that the warm water is used because the heat is efficiently transmitted, and the time until the temperature of the metal support is fixed is short. When the warm air is used, it is considered that the temperature of the mesh is lowered due to the latent heat of evaporation of the solvent, and it is also possible to prevent foaming while using a temperature of the boiling point or higher of the solvent, and to use a wind having a temperature higher than the target temperature. In particular, it is preferable to change the temperature of the support and the temperature of the dry air between the self-casting and the peeling, and to perform drying efficiently.

The die system is preferably capable of adjusting the narrowness of the metal mouth portion of the die The shape of the slit is made, and the film thickness is easily made uniform. A hanger type die or a T die or the like can be preferably used in the press die. The surface of the metal support is mirrored. In order to increase the film forming speed, two or more press dies may be provided on the metal support, and the amount of the sizing may be divided and laminated.

(2.2) Solvent evaporation step

The step of heating the mesh on the metal support for casting and evaporating the solvent controls the amount of residual solvent at the time of peeling.

In order to evaporate the solvent, there is a method of blowing air from the mesh side, a method of transferring heat from the back of the support by liquid, a method of transferring heat from the surface by radiant heat, etc., but the back liquid heat transfer method is effective in drying. More suitable. Also, it is better to combine their methods. Preferably, the web on the cast support is dried on the support in an environment of 30 to 100 ° C. In order to maintain the environment in the range of 30 to 100 ° C, it is preferred to apply warm air of this temperature to the mesh or to heat by means of infrared rays or the like.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferred to peel the web from the support in the range of 30 to 180 seconds.

(2.3) Stripping step

The step of peeling off the web on which the solvent has evaporated on the metal support in the peeling position. The peeled web is sent as a film to the next step.

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

In the present invention, the solvent in the mesh sheet is evaporated in the solvent evaporation step, but the residual solvent amount of the mesh on the metal support at the peeling time point is preferably in the range of 15 to 100% by mass. The control of the amount of the residual solvent is preferably carried out by the drying temperature and the drying time in the solvent evaporation step described above.

When the amount of the residual solvent is 15% by mass or more, in the drying process on the support, since the vermiculite particles do not have a distribution in the thickness direction, it is preferably in a state of being uniformly dispersed in the film.

In addition, when the amount of the residual solvent is 100% by mass or less, the film is self-supporting, the peeling failure of the film can be avoided, and the mechanical strength of the mesh can be maintained, so that the planarity at the time of peeling is improved, and the peeling tension can be suppressed. The occurrence of unevenness or vertical stripes occurs.

The residual solvent amount of the mesh or film is defined by the following formula (Z).

The amount of residual solvent (%) of formula (Z) = (mass before heat treatment of mesh or film - mass after heat treatment of mesh or film) / (mass after heat treatment of mesh or film) × 100

In addition, the heat treatment at the time of measuring the residual solvent amount is a heat treatment performed at 115 ° C for 1 hour.

The peeling tension when the web is peeled off from the metal support to form a film is usually in the range of 196 to 245 N/m. However, when wrinkles are easily introduced during peeling, it is preferably peeled off at a tension of 190 N/m or less.

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

(3) Drying and stretching steps

The drying step can also be carried out by dividing into a preliminary drying step and a formal drying step.

(3.1) Pre-drying step

The film obtained by peeling the mesh from the metal support is pre-dried. The preliminary drying of the film can be carried out by transporting the film while being placed on a plurality of rolls on the upper and lower sides, or the both ends of the film can be fixed by a clip as in a tenter dryer, and dried while being conveyed.

The means for drying the web is not particularly limited, and it can be generally carried out by hot air, infrared rays, heating rolls, microwaves, etc., but it is preferably carried out by hot air at the point of simplicity.

The drying temperature of the preliminary drying step of the mesh sheet is preferably a glass transition point of the film of -5 ° C or less, and it is effective to perform heat treatment at a temperature of 30 ° C or higher for 1 minute or longer and 30 minutes or shorter. Drying is carried out in the range of drying temperature of 40 to 150 ° C, more preferably 50 to 100 ° C.

(3.2) Extension step

The second protective film of the present invention can be dissolved in the extension device 34. The stretching treatment is carried out at a dose to uniformly disperse the vermiculite particles in the resin in the film, or to improve the planarity of the film, or to control the molecular alignment in the film to obtain the desired hysteresis values Ro and Rt. As the stretching method, it may be a uniaxial extension or a biaxial extension, and when the biaxial stretching is performed, the sequential stretching method, the simultaneous stretching method, and the oblique stretching method may be used.

In the method for producing a cycloolefin film of the present invention, in the step of stretching the film, the amount of residual solvent at the start of stretching is preferably 1% by mass or more and less than 15% by mass, more preferably 2 to 10%. Within the range of the mass %, if it is in the range of the amount of the residual solvent, it is possible to prevent uneven stress from being applied to the film during stretching.

The cycloolefin film of the present invention is also preferably extended in the longitudinal direction (also referred to as MD direction, casting direction) and/or width direction (also referred to as TD direction) and/or oblique direction, preferably by at least The extension device is manufactured by extending in the width direction.

The extension operation can also be implemented by dividing into multiple stages. Further, when the biaxial stretching is performed, the biaxial stretching may be performed simultaneously or in stages. In this case, the so-called stages may be, for example, extensions of different extension directions may be sequentially performed, or extensions of the same direction may be divided into multiple stages, and extensions of different directions may be applied in any of the stages.

That is, for example, the following extension steps are also possible:

‧ Extension in the length direction → Extension in the width direction → Extension in the length direction → Extension in the length direction

‧Extension in the width direction→Extension in the width direction→Extension in the length direction→Extension in the length direction

‧Extension in the width direction→Extension in the oblique direction

Further, in the simultaneous biaxial stretching, it also includes a case where the tension is relaxed in one direction and the tension is relaxed in the other direction.

The cycloolefin film of the present invention preferably has a film thickness after stretching in a desired range, and preferably in the width direction in the longitudinal direction and/or the width direction, when the glass transition temperature of the film is Tg. It extends in the temperature range of (Tg + 5) ~ (Tg + 50) °C. When extending in the above temperature range, the adjustment of the phase difference is easy, and the haze is lowered because the elongation stress can be lowered. Further, the occurrence of cracking is suppressed, and a protective film excellent in flatness and coloring property of the film itself is obtained. The stretching temperature is preferably carried out in the range of (Tg + 10) to (Tg + 40) °C.

In addition, the glass transition temperature Tg mentioned here is the measurement of the intermediate point glass transition temperature (Tmg) according to JISK7121 (1987) using a commercially available differential scanning calorimeter at a temperature increase rate of 20 ° C / min. ). The method for measuring the glass transition temperature Tg of a specific film is measured in accordance with JIS K7121 (1987) using a differential scanning calorimeter DSC220 manufactured by SEIKO Instruments.

Preferably, the cycloolefin film of the present invention has an elongation at a range of from 1 to 60% with respect to the original width at least in the width direction, and more preferably in the longitudinal direction and the width direction of the film. Extends in an elongation range of 5 to 40%. In particular, the range of the elongation is more preferably in the range of 10 to 30% with respect to the original width. The elongation as used in the present invention means the ratio of the length of the long side or the broad side of the stretched film with respect to the length of the long side or the wide side of the film before stretching. (%).

The method of extending in the longitudinal direction is not particularly limited. For example, a method of giving a peripheral speed difference to a plurality of rolls and extending in the longitudinal direction by a difference in circumferential speed of the rolls may be used, and the ends of the mesh are fixed by clips or needles to enlarge the interval of the clips or the needles in the traveling direction. The method of extending in the longitudinal direction, or the method of expanding vertically and horizontally and extending in both the longitudinal and lateral directions, and the like. Of course, these methods can also be used in combination.

In the width direction, for example, a step of drying or a part of the drying as shown in Japanese Laid-Open Patent Publication No. 62-46625 is used, and both ends of the width of the mesh are kept wide by a clip or a needle in the width direction. One side drying method (also known as tentering method), which is preferably used: the tentering method using the clip and the needle tentering method using the needle.

When extending in the width direction, it is preferable to extend at an elongation speed in the range of 100 to 500%/min in the film width direction.

If the stretching speed is particularly 250%/min or more, since the flatness is improved and the film is processed at a high speed, it is preferable from the viewpoint of production suitability, and if it is within 500%/min, the film can be processed without breaking. It is more suitable for processing.

The preferred stretching speed is in the range of 300 to 400%/min, which is effective at the extension of low magnification. The elongation speed is defined by the following formula 1.

Equation (D) Extension speed (%/min) = [(d ₁ /d ₂ )-1]×100(%)/t

In the formula (D), d ₁ is a width dimension of the second protective film of the present invention in the extending direction, and d ₂ is a width dimension of the second protective film before extending in the extending direction, and t is required for stretching. Time (min).

The cycloolefin film of the present invention can impart a desired retardation value by stretching.

The film thickness of the cycloolefin film of the present invention is preferably from 5 to 80 μm, particularly preferably from 20 to 60 μm. When the in-plane retardation Ro of the measurement wavelength of 590 nm and the phase difference Rt in the thickness direction are each (iii) 40 ≦ Ro ≦ 300 and (iv) 100 ≦ Rt ≦ 400, when used as the second protective film, It is preferable to provide a light-weight and thin film polarizing plate and to provide a phase difference which is most suitable as a polarizing plate for a VA mode liquid crystal display device. More preferably, it is within the range of (iii) 50≦Ro≦200, (iv) 100≦Rt≦300.

In the extension step, usually after the extension, the retention is moderated. That is, this step is preferably carried out in sequence: an extension phase of the stretched film, a holding phase in which the film is held in an extended state, and a relaxation phase in which the film is relaxed in the direction of the stretched film. In the hold phase, the extension of the elongation achieved during the extension phase is maintained at the extension temperature of the extension phase. In the relaxation phase, after the extension in the extension phase is maintained in the retention phase, the extension is relaxed by releasing the tension for extension. The mitigation phase can be carried out below the extension temperature of the extension phase.

(3.3) Drying step

In the drying step, the stretched film is heated by a drying device 35 to be dried.

In order to adjust the amount of the organic solvent contained in the film, it is preferred to carry out the conditions of the drying step as appropriate.

When the film is heated by hot air or the like, it is also preferable to use a means which is provided with a nozzle capable of exhausting used hot air (air containing solvent or humidified air) to prevent the incorporation of used hot air. The hot air temperature is preferably in the range of 40 to 350 °C. Further, the drying time is preferably from about 5 seconds to 60 minutes, more preferably from 10 seconds to 30 minutes.

Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rolls, microwaves, or the like can be used. From the viewpoint of simplicity, it is preferable to carry the film by hot air or the like while conveying the film by the conveyance rollers 36 arranged in a staggered shape. The drying temperature is preferably in the range of 40 to 350 ° C in consideration of the amount of residual solvent, the expansion ratio during transportation, and the like.

In the drying step, the amount of the residual solvent is generally preferably such that the film is dried until it is 0.5% by mass or less.

(4) Winding step

(4.1) Knurling

After the specified heat treatment or cooling treatment, a slitter is provided before the winding to cut off the end portion, and a good winding posture is obtained, which is preferable. Further, it is preferable to perform knurling processing on both end portions of the wide side.

The knurling process can be formed by pushing a heated embossing roll to the wide end of the film. Fine irregularities are formed on the embossing roll, and by forming a concavity and convexity on the film by pushing it, the end portion can be bulky.

The knurling height of the both ends of the wide side of the second protective film of the present invention is high The degree is preferably in the range of 4 to 20 μm and the width is in the range of 5 to 20 mm.

(4.2)

As another means for obtaining a good winding attitude, for the purpose of preventing adhesion of the films to each other before winding, the masking film (also referred to as a protective film) may be overlapped and simultaneously wound, or the film may be stretched. At least one end, preferably at both ends, is wound while being taped or the like. The masking film is not particularly limited as long as it can protect the film, and examples thereof include a polyethylene terephthalate film, a polyethylene film, and a polypropylene film.

Further, in the present invention, the knurling described above is preferably performed after the drying in the film forming step of the film is completed and before the winding.

(4.3) Rolling step

When the amount of the residual solvent in the film is 2% by mass or less, the amount of the residual solvent is preferably 1% by mass or less, more preferably 0.1% by mass or less, and the dimensional stability is good. film.

The coiling method can be used as long as it is a general user, and has a fixed moment method, a fixed tension method, a taper tension method, and a planned tension control method with a constant internal stress, and can be flexibly applied to them.

(melt casting film forming method)

The cycloolefin film of the present invention can also be formed by melt casting film forming method Hereinafter, it is also referred to as a melt extrusion method, and an example is shown below.

The method for producing a cycloolefin film by melt extrusion is a step (A) of forming a cycloolefin film by extruding a cycloolefin resin heated and melted at a temperature higher than a glass transition temperature into a film form from a die. The step (C) of receiving the cycloolefin film by the film forming support and cooling the film (B) is carried out by a horizontal uniaxial, sequential or simultaneous biaxial stretching. The cycloolefin resin heated to a temperature equal to or higher than the glass transition temperature is melted, but the cycloolefin resin is cooled to be less than the glass transition temperature and hardened. Therefore, a soft cycloolefin resin having a glass transition temperature or higher is formed into a film shape, and then cooled and hardened, whereby a desired cycloolefin film can be obtained by an extension step.

In at least the step (B) of the foregoing steps (A) and (B) of the method for producing a cycloolefin film, it is preferred to provide a first stretch region between the central region of the resin film and the first fixed region, and A second stretched region is disposed between the central region of the resin film and the second stretched region. Therefore, in the step (B), the cycloolefin film has, in the width direction thereof, a first fixed region, a first stretched region, a central region, a second stretched region, and a second fixed region in this order. Further, the first stretched region and the second stretched region are provided such that the elongation of the first stretched region and the second stretched region is greater than the amount of elongation of the central region when the same tension is applied.

By having such a configuration, the method for producing a cycloolefin film can produce a cycloolefin film having a hysteresis value Rt in the thickness direction defined by the present invention in the central portion thereof.

Furthermore, if ultraviolet light is added to the cycloolefin film In the case of the receipt, there is a case where the hysteresis value rises, so the selection or content of the ultraviolet absorber or the setting of the film thickness of the film becomes important. As the ultraviolet absorber, a benzotriazole-based compound is preferred.

Next, a method for producing a cycloolefin film by a melt casting method will be described using the drawings alternately.

Fig. 3 is a view schematically showing an example of a dope preparation step, a casting step, and a drying step which can be applied to the melt casting method of the present invention.

As shown in Fig. 3, a manufacturing apparatus (400) for a cycloolefin film (410) includes a die (510), a casting roll (520) as a support, and electrostatic pinning devices (531 and 532) as an adhesion device, As a peeling device, a peeling roller (540), a trimming device (550), an extending device (not shown), a shielding device (not shown), and a take-up shaft (560) as a winding device.

The die (510) is provided for use in a resin supply device (not shown), and a single resin having a temperature equal to or higher than the glass transition temperature is supplied as indicated by an arrow A ₁₁₀ . Further, the die (510) is provided for extruding the resin thus supplied into a film shape through the lip (516) to obtain a resin film (420) made of a resin in a molten state.

As shown in Fig. 3, the casting roll (520) has an outer peripheral surface (521) as a roll capable of receiving a support surface of the cycloolefin film (420) extruded from the die (510). This casting roll (520) is placed at a position opposite to the die (510).

Further, the casting roll (520) is provided to be rotatable as indicated by an arrow A ₁₂₀ by a driving force given from a driving device (not shown). Therefore, the casting roll (520) has a configuration in which the cycloolefin film (420) received on the outer peripheral surface (521) can be conveyed by the rotation of the casting roll (520).

Furthermore, the casting rolls (520) can be provided with temperature adjustment. Therefore, the casting roll (520) has a configuration capable of cooling the cycloolefin film (420) received on the outer peripheral surface (521) to a desired temperature. The temperature of the casting roll (520) is set to be a cyclic olefin during the period from the reception of the cycloolefin film (420) on the circumferential surface (521) of the casting roll (520) to the peeling by the peeling roll (540). The film (420) is cooled to a temperature below the glass transition temperature of the resin contained in the cycloolefin film (420).

The peeling roller (540) is arranged in parallel with the casting roll (520) so as to be rotatable as indicated by an arrow A ₁₄₀ . Further, the peeling roller (540) is provided so as to be capable of peeling off the glass transition temperature of the resin contained in the cycloolefin film (420) by the casting roll (520) from the outer peripheral surface (521) of the casting roll (520). The following cycloolefin film (420). Further, the peeling roller (540) is provided to be able to feed the peeled cycloolefin film (420) to the trimming device (550).

The trimming device (550) is a device for removing at least the first fixed region and the second fixed region from the cycloolefin film (420) peeled off via the peeling roller (540).

The trimming device (550) is provided with a blade on the outer circumference, and includes trimming blades (551 and 552) provided in pairs. The trimming device (550) is configured to cut the end film (428) from the cycloolefin film (420), and send the cycloolefin film (410) containing the remaining central region to the stretching device, and trimming the device in the extension The trace of the end portion due to the device is shielded from the cycloolefin film containing the remaining central region, and the masking film protruded from the cycloolefin film is removed by the trimming device, and the remaining central region is included. The masked cycloolefin film is sent to a take-up shaft (560). By imparting process adaptability to the cycloolefin film, the unmasked film can also be stably wound up.

The stretching ratio as the stretching step is in the range of 1.01 to 1.60 in total in the aspect ratio. As the stretching method, any one of uniaxial stretching, biaxial stretching, or oblique stretching may be employed.

The take-up shaft (560) is provided to rotate as indicated by an arrow A ₁₆₀ by a drive device (not shown). Therefore, the winding device (560) has a configuration in which a cycloolefin film (410) sent from the trimming device (550) is taken up to obtain a film roll (430).

As described above, a cycloolefin film (410) which is applicable as the second protective film is obtained.

Further, the cycloolefin film (410) produced by such a method generally has high transparency from the viewpoint of use as the second protective film. Specifically, the total light transmittance of the cycloolefin film (410) in terms of 1 mm thick is preferably 80% or more, and more preferably 90% or more. Further, the haze of the cycloolefin film in terms of 1 mm thick is preferably 0.3% or less, and particularly preferably 0.2% or less. Here, the total light transmittance can be measured in accordance with JIS K7361-1997. Further, the haze can be measured in accordance with JIS K7136-1997.

For details of the method for producing a cycloolefin film by a melt casting method and the cycloolefin resin to which it can be applied, for example, the contents described in JP-A-2015-187629 can be referred to.

Polarizer

The polarizing plate of the present invention is an ultraviolet curing type adhesive or a water system. In the coating, the first protective film and the second protective film of the present invention are bonded to both surfaces of the polarizing mirror.

Moreover, when the polarizing plate of the present invention is used as the polarizing plate on the visual recognition side, it is preferable to provide an anti-glare layer or a transparent hard coat layer, an anti-reflection layer, an antistatic layer, and an antifouling layer on the protective film for the polarizing plate. Layers, etc.

[Polarizer]

The polarizer which is a main component of the polarizing plate of the present invention is an element which passes only light of a polarized wave surface in a certain direction, and a representative polarizer which is currently known is a polyvinyl alcohol-based polarizing film. Among the polyvinyl alcohol-based polarizing films, those obtained by dyeing iodine to a polyvinyl alcohol-based film and dyeing a dichroic dye are used.

As the polarizing lens, a polarizing lens which is formed by laminating a polyvinyl alcohol aqueous solution, and which is uniaxially stretched and dyed, or uniaxially stretched after dyeing, is preferably subjected to durability treatment with a boron compound. The film thickness of the polarizer is preferably 2 to 30 μm, and particularly preferably 2 to 15 μm.

In addition, it is preferable to use the ethylene unit content of 1 to 4 mol%, the polymerization degree of 2000 to 4000, and the degree of saponification of 99.0 to 99.99 as described in JP-A-2003-248123, JP-A-2003-342322, and the like. Ears of ethylene modified polyvinyl alcohol. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cut-off temperature of 66 to 73 ° C is preferably used. The polarizer using the ethylene-modified polyvinyl alcohol film is excellent in polarizing performance and durability, and has low color unevenness, and is particularly preferably used in a large liquid crystal display device.

[Production of polarizing plate]

The polarizing plate of the present invention can be produced by a general method. The polarizing mirror facing surface side of the first protective film of the present invention can be suitably surface-treated on at least one surface of a polarizing mirror which is formed by immersing and stretching in an iodine solution, and is adhered by using an ultraviolet curing adhesive or a water-based adhesive which will be described later. Hehe. The second protective film is also attached to the other side.

The bonding method with the polarizer is preferably bonded such that the absorption axis of the polarizer and the slow axis of each protective film are orthogonal to each other.

(UV curing adhesive)

In the polarizing plate of the present invention, the protective film and the polarizing mirror of the present invention are preferably followed by an ultraviolet curing type adhesive.

In the present invention, by using an ultraviolet curable adhesive for bonding the protective film and the polarizer, the strength is high even in the case of a film, and a polarizing plate excellent in planarity can be obtained.

<Composition of ultraviolet curing type adhesive>

As an ultraviolet curable adhesive composition for a polarizing plate, a photoradical polymerization type composition by photoradical polymerization, a photocationic polymerization type composition by photocationic polymerization, and photo-radical polymerization and photocation are used in combination. Polymerized mixed composition.

As a photo-radical polymerization type composition, a radically polymerizable compound containing a polar group such as a hydroxyl group or a carboxyl group and a free radical-free group described in JP-A-2008-009329 are known. A composition of a base polymerizable compound or the like. In particular, the radically polymerizable compound is preferably a radically polymerizable compound having an ethylenically unsaturated bond. In a preferred embodiment of the compound having an ethylenically unsaturated bond which is polymerizable by a radical, a compound having a (meth) acrylonitrile group is contained. Examples of the compound having a (meth)acryl fluorenyl group include an N-substituted (meth) acrylamide-based compound, a (meth) acrylate-based compound, and the like. (Meth)acrylamide refers to acrylamide or methacrylamide.

Further, the photocationic polymerization type composition includes (α) a cationically polymerizable compound, (β) a photocationic polymerization initiator, and (γ) for a ratio of 380 nm as disclosed in JP-A-2011-028234. The long-wavelength light shows a UV-curable adhesive composition of each component of the photosensitive sensitizer and the (δ) naphthalene-based photo-sensitizing aid. However, an ultraviolet curable adhesive other than this may be used.

(1) Pre-processing steps

The pre-treatment step is a step of facilitating subsequent processing of the protective film with the bonding surface of the polarizer. Examples of the easy subsequent treatment include corona treatment, plasma treatment, and the like.

(coating step of ultraviolet curing type adhesive)

As the coating step of the ultraviolet curable adhesive, the ultraviolet curable adhesive is applied to at least one of the polarizing mirror and the adhesion surface of the protective film for the polarizing plate. When the ultraviolet curable adhesive is directly applied to the surface of the polarizer or the protective film, the coating method is not particularly limited. example For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a notch wheel coater, and a gravure coater can be used. Further, it is also possible to apply a method in which an ultraviolet curable adhesive is applied between a polarizer and a protective film, and then uniformly pressed by a roller or the like.

(2) Lamination step

After the ultraviolet curable adhesive is applied by the above method, it is treated in a bonding step. In this bonding step, for example, when a UV curable adhesive is applied to the surface of the polarizer in the previous coating step, a cellulose resin film is laminated thereon. Further, when an ultraviolet curable adhesive is applied to the surface of the first or second protective film, a polarizer is superposed thereon. Further, when the ultraviolet curable adhesive is cast between the polarizer and the protective film, the polarizer and the protective film are laminated in this state. Then, in this state, it is usually pressed from the side of the protective film on both sides, and is pressed by a pressure roller or the like. The material of the pressure roller can be metal or rubber. The pressure roller system disposed on both sides can be the same material or different materials.

(3) Hardening step

In the hardening step, the uncured ultraviolet curable adhesive is irradiated with ultraviolet rays to contain a cationically polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate system). The ultraviolet curable adhesive layer of the compound, the acrylamide compound or the like is cured, and the polarizing mirror and the protective film of the present invention are laminated via an ultraviolet curing adhesive. Apply a protective film to both sides of the polarizer In the configuration of the present invention, it is advantageous to irradiate ultraviolet rays in a state in which a protective film is superimposed on both surfaces of the polarizer via an ultraviolet curable adhesive, and to cure both of the ultraviolet curable adhesives at the same time.

The ultraviolet irradiation conditions may be any suitable conditions as long as the ultraviolet curable adhesive which is suitable for use in the present invention is cured. The amount of ultraviolet rays to be irradiated is preferably in the range of 50 to 1,500 mJ/cm ² , more preferably in the range of 100 to 500 mJ/cm ² , in terms of integrated light amount. In the present invention, it is also preferred to irradiate ultraviolet rays from the side of the first protective film in order to improve the yield.

When the process of the polarizing plate is carried out in a continuous production line, the linear velocity is preferably in the range of 1 to 500 m/min, more preferably in the range of 5 to 300 m/min, and more preferably 10 in the range of 1 to 500 m/min. Within the range of ~100m/min. When the linear velocity is 1 m/min or more, productivity can be ensured, damage to the protective film of the present invention can be suppressed, and a polarizing plate excellent in durability can be produced. In addition, when the linear velocity is 500 m/min or less, the curing of the ultraviolet curable adhesive is sufficient, and an ultraviolet curable adhesive layer having excellent hardness and adhesion can be formed.

"Liquid Crystal Display Device"

By using the polarizing plate of the present invention to which the protective film of the present invention is bonded, the liquid crystal display device of the present invention can be produced in various liquid crystal display devices having excellent visibility.

The polarizing plate of the present invention can be used for various driving methods of STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB, and the like. Liquid crystal display device. A VA type liquid crystal display device is preferred.

In the liquid crystal display device, two polarizing plates of the polarizing plate on the viewing side and the polarizing plate on the backlight side are usually used. However, it is preferable to use the polarizing plate of the present invention as both polarizing plates, and it is also preferable to use it as a single sheet. Side polarizer.

The bonding method of the above-mentioned polarizing plate in the VA liquid crystal display device can be carried out by referring to Japanese Laid-Open Patent Publication No. 2005-234431.

The liquid crystal cell used in the present invention includes a liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer, and the glass substrate in the range of 0.3 to 0.7 mm in thickness of the pair of substrates is thinned and lightened from the liquid crystal display device. The point of view is more appropriate.

4 is a schematic cross-sectional view showing an example of a configuration of a liquid crystal display device (100) in which the polarizing plates (101A and 101B) of the present invention described above are disposed on both surfaces of a liquid crystal cell (101C).

In Fig. 4, the liquid crystal cells (101C) are formed by sandwiching both surfaces of the liquid crystal layer (107) with glass substrates (108A and 108B) as transparent substrates, and are formed on the respective surfaces of the respective glass substrates (108A and 108B). The adhesive layer (106) is placed, and the polarizing plates (101A and 101B) shown in FIG. 4 are arranged to constitute the liquid crystal display device 100.

In the configuration of the liquid crystal display device (100) shown in FIG. 4, the polarizing plate having the second protective film formed by the configuration defined by the present invention may be applied to the polarizing plate (101A) or may be applied to The configuration of the polarizing plate (101B) may be applied to both of the polarizing plate (101A) and the polarizing plate (101B). Liquid crystal display device using the polarizing plate of the present invention Particularly preferred is a VA type liquid crystal display device.

The liquid crystal cell (101C) is configured by disposing an alignment film, a transparent electrode, and a glass substrate (108A and 108B) on both surfaces of the liquid crystal material.

By providing a polarizing plate of the present invention which is excellent in durability, flatness, and the like and improved in yield in a liquid crystal display device, even if a glass substrate constituting a liquid crystal cell is formed into a thin film, panel bending is less likely to occur, and as a result, A liquid crystal display device in which film formation is achieved is obtained.

Examples of the material constituting the glass substrate (108A and 108B) which can be used for the liquid crystal cell (101C) include soda lime glass, silicate glass, etc., preferably silicate glass, and more preferably vermiculite. Glass or borosilicate glass.

The glass constituting the glass substrate is preferably an alkali-free glass which does not substantially contain an alkali component, and specifically, a glass having an alkali component content of 1000 ppm or less is preferably used. The content of the alkali component in the glass substrate is preferably 500 ppm or less, more preferably 300 ppm or less. The glass substrate containing an alkali component is substituted with a cation on the surface of the film, and a phenomenon of causing alkali is likely to occur. Therefore, the density of the surface layer of the film is liable to lower, and the glass substrate is easily broken.

The thickness of the glass substrates (108A and 108B) constituting the liquid crystal cell of the liquid crystal display device is preferably in the range of 0.3 to 0.7 mm. Such a thickness is preferable in that it can contribute to the formation of a thin film formation of a liquid crystal display device.

The glass substrate can be formed by a well-known method such as a float method, a down-draw method, an overflow down-draw method, or the like. Among them, the surface of the glass substrate is not in contact with the forming member at the time of molding, and it is difficult to damage the obtained glass base. The surface of the material, etc., is preferably an overflow downdraw method.

In addition, such a glass substrate can be obtained as a commercially available product, and, for example, an alkali-free glass AN100 (thickness: 500 μm) manufactured by Asahi Glass Co., Ltd., and a glass substrate EAGLE XG (r) Slim (thickness: 300 μm, 400 μm, etc.) manufactured by CORNING Co., Ltd. A glass substrate (thickness: 100 to 200 μm) manufactured by Nippon Electric Glass Co., Ltd.

Further, the polarizing plates (101A, 101B) shown in Fig. 4 and the glass substrates (108A and 108B) constituting the liquid crystal cell (101C) are each adhered via an adhesive layer (106).

As the adhesive layer, a double-sided tape such as a double-sided tape (substrate-free tape MO-3005C) made of a thickness of 25 μm manufactured by LINTEC Co., Ltd., or the like, or a composition used in the formation of the above-mentioned active light-curable resin layer can be used.

In addition to the effects of the present invention, the liquid crystal display device using the polarizing plate of the present invention is excellent in adhesion between layers, excellent in fading resistance, and egg-type unevenness in displaying images.

The bonding of the surface of the retardation film side of the polarizing plate to at least one surface of the liquid crystal cell is carried out by a well-known method. Depending on the situation, it can also be applied through the back layer.

By using the polarizing plate of the present invention, particularly in the case of a liquid crystal display device having a large screen of 30 or more screens, panel bending can be suppressed, and visibility such as display unevenness and front contrast can be excellent, and the film can be lightened. Liquid crystal display device.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited thereto. In addition, the expression "part" or "%" is used in the examples, but "quality by mass" or "mass%" is used unless otherwise specified.

Example 1

"Production of the first protective film"

The first protective films PET1 to PET4 which are polyester films were produced in accordance with the method described below.

[Production of the first protective film PET1]

(Modulation of Polyester Resin A)

The esterification reaction vessel was heated, and 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged at 200 ° C, and while stirring and stirring, 0.017 parts by mass of antimony trioxide as a catalyst and 0.064 parts by mass of acetic acid were charged. Magnesium tetrahydrate, 0.16 parts by mass of triethylamine. The pressure esterification reaction was carried out under the conditions of a gauge pressure of 0.34 MPa and a temperature of 240 °C.

Next, the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, 0.012 parts by mass of trimethyl phosphate was added by heating to 260 ° C for 15 minutes. Then, after 15 minutes, the dispersion treatment was carried out in a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tank, and a polycondensation reaction was carried out at 280 ° C under reduced pressure.

After completion of the polycondensation reaction, the mixture was filtered by Nasolon Filter NF-05S manufactured by Nippon Seisen Co., Ltd., and strands were extruded from a nozzle, and subjected to filtration treatment (pore diameter: 1 μm or less), followed by cooling with cooling water. , curing, cutting the resin into pellets. The obtained polyester resin A (polyethylene terephthalate resin A) had an intrinsic viscosity of 0.62 cm ³ /g, and substantially contained no inert particles and internal precipitated particles.

(Modulation of coating liquid for forming an intermediate layer)

The transesterification reaction and the polycondensation reaction are carried out by a usual method to prepare a dicarboxylic acid component (to the entire dicarboxylic acid component), and 46 mol% of terephthalic acid and 46 mol% of isophthalic acid are used. 8 mol% sodium 5-sulfonate isophthalate, containing 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as a diol component (total of the diol component) containing water dispersion A copolymerized polyester resin of a metal sulfonic acid metal base.

Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, and 0.06 parts by mass of a nonionic surfactant were mixed with heating, and after reaching 77 ° C, 5 parts by mass of the above-mentioned content was added. The copolymerized polyester resin of the water-dispersible sulfonic acid metal base is heated and stirred until the resin block disappears, and the aqueous resin dispersion liquid is cooled to room temperature to obtain a uniform water-dispersible copolymerization polymerization having a solid concentration of 5.0% by mass. Ester resin liquid.

In addition, 3 parts by mass of agglomerated vermiculite particles (manufactured by FUJI SILYSIA Co., Ltd., Sylysia 310) was dispersed in 50 parts by mass of water. To Sylysia, 99.5 parts by mass of the above water-dispersible copolymerized polyester resin liquid In an amount of 0.54 parts by mass of the aqueous dispersion of 310, 20 parts by mass of water was added thereto with stirring to prepare a coating liquid for forming an adhesive layer.

(Production of polyester film)

The above-prepared polyester A was dried by a usual method, supplied to an extruder, melted at 285 ° C, and filtered with a filter material of a stainless steel sintered body (nominal filtration accuracy of 10 μm particles 95% cutoff), from the metal port. After extruding into a sheet shape, it was wound on a casting drum having a surface temperature of 30 ° C by an electrostatic application casting method, and cooled and solidified to prepare an unstretched polyester film (PET film).

Then, the coating liquid for forming an adhesive layer for forming an adhesive layer prepared as described above was applied to both surfaces of the unstretched PET film by a reverse roll method so that the coating amount after drying was 0.08 g/m ² . Thereafter, it was dried at 80 ° C for 20 seconds.

The unstretched film formed with the adhesion improving layer was guided to a tenter stretching machine, and the end portion of the film was grasped by a clip while extending to 4.0 times in the width direction in the heating zone at a temperature of 125 °C.

Next, the width extending in the width direction was maintained, the temperature was treated at 225 ° C for 30 seconds, and the relaxation treatment was performed at 3.0% in the width direction to prepare a uniaxially-oriented polyterephthalic acid having a film thickness of 60 μm. The first protective film PET1 of the ethylene glycol film.

[Production of the first protective film PET2]

In the production of the first protective film PET1, the adjustment is not extended. The thickness of the film was used to produce a first protective film PET2 having a thickness of 80 μm after stretching.

[Production of the first protective film PET3]

Mixing 10 parts by mass of the dried ultraviolet absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazinone-4-one) with 90 parts by mass of poly The ester film (inherent viscosity: 0.62 cm ³ /g) was used, and a protective film PET3 of a polyester film having a thickness of 100 μm containing an ultraviolet absorber was produced using a first extruder.

[Production of the first protective film PET4]

Using the first protective film PET1 produced above, a cured resin layer (hard coat layer) was formed on one surface side in accordance with the following method.

(Formation of hardened resin layer (hard coat layer))

The following curable resin composition 1-1 was applied onto the first protective film PET1 having the adhesion-improving layer, and dried in a hot oven at 70 ° C for 60 seconds to evaporate the solvent in the coating film. The ultraviolet light was irradiated with an integrated light amount of 50 mJ/cm ² to perform semi-hardening to form a first coating film. Next, the following curable resin composition 2-1 was applied as a second curable resin composition on the semi-cured first coating film, and dried in a hot oven at a temperature of 70 ° C for 60 seconds to form a coating film. The solvent was evaporated, and the ultraviolet light was irradiated with an integrated light amount of 200 mJ/cm ² to be fully cured. The second coating film (upper layer) having a dry film thickness of 13 μm was laminated on the first coating film (common bonding layer) having a dry film thickness of 2 μm. And a hardened resin layer (hard coat layer) is formed.

<Modulation of Curable Resin Composition 1-1>

Adhesive component 1: 6-functional dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., product name: DPHA) 100 parts by mass

Polymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4 parts by mass

Solvent: methyl isobutyl ketone 150 parts by mass

<Modulation of Curable Resin Composition 2-1>

Reactive heteromorphic fine-grain particles: an average primary particle diameter of 20 nm of vermiculite particles by an average of 3.5 inorganic chemical bonds, a long axis length of 60 nm, a solid content of 40%, and a dispersion medium IPA solvent of 150 parts by mass (solid content of 60 parts by mass) )

Adhesive component 1: 6-functional dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., product name: DPHA) 20 parts by mass

Adhesive component 2: 30 functional or more, polymer acrylate having a weight average molecular weight of 40,000 (manufactured by Arakawa Chemical Co., Ltd., product name: BS371) 31 parts by mass (solid content: 20 parts by mass)

Polymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4 parts by mass

Leveling agent: 4 parts by mass of Megafac MCF350-5 (made by DIC) (solid content 0.2 parts by mass)

Solvent: methyl isobutyl ketone 54 parts by mass

The characteristic values of PET1 to PET4 of the first protective film produced above are as follows.

PET1: film thickness = 60 μm, ultraviolet transmittance at 380 nm = 50% or more, hard coat layer = none, hysteresis value Ro = 6 × 10 ^-3 nm

PET2: film thickness = 80 μm, ultraviolet transmittance at 380 nm = 50% or more, hard coat = no, hysteresis value Ro = 8 × 10 ^-3 nm

PET3: film thickness = 100 μm, ultraviolet transmittance at 380 nm = less than 50%, hard coat = no, hysteresis value Ro = 3 × 10 ^-3 nm

PET4: film thickness = 60μm, ultraviolet transmittance at 380nm = 50% or more, hard coating = yes, hysteresis value Ro = 6 × 10 ^-3 nm

"Production of the second protective film"

The second protective films 1 to 39 using a cellulose resin were produced in accordance with the method described below.

[Details of Cellulose Resin and Various Additives]

First, the details of the cellulose resin and various additives used in the production of the second protective films 1 to 39 are shown below.

[Cellulose resin]

Cellulose Resin A: Cellulose Acetate Propionate (Ethylene Substrate Substitution = 1.5, Propyl Group Substitution = 0.9)

Cellulose Resin B: Cellulose Acetate Propionate (Ethylene Substrate Substitution = 1.4, Propyl Group Substitution = 1.1)

Cellulose resin C: Cellulose acetate butyrate (acetamyl substitution = 2.2, butyl group substitution = 0.3)

Cellulose resin D: cellulose acetate butyrate (acetamyl substitution = 2.1, butyl group substitution = 0.2)

Cellulose resin E: Ethylcellulose (acetamyl substitution = 2.8)

Cellulose resin F: Ethylcellulose (acetamyl substitution = 2.7)

Cellulose resin G: Ethylcellulose (acetamyl substitution = 2.4)

[various additives]

(sugar ester)

Table I shows the details of the sugar esters A to F used in the production of the second protective film.

(polyester compound)

<Modulation of Polyester Compound A>

251 g of 1,2-propanediol, 278 g of phthalic anhydride, 91 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. In the middle, the temperature was gradually increased while stirring in a nitrogen stream until it reached 230 °C. As the terminally blocked monocarboxylic acid (B1), 610 g of benzoic acid was added. The dehydration condensation reaction was carried out for 15 hours. After the completion of the reaction, the unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain a polyester compound A. The acid value was 0.10 mgKOH/g, and the number average molecular weight was 450.

<Modulation of Polyester Compound B~H>

In the preparation of the polyester compound A, the polyester compounds B to H were prepared in the same manner except that the types of the dicarboxylic acid, the diol, and the monocarboxylic acid were changed to the combinations described in Table 2.

The details of the polyester compounds A to H prepared by the above methods are shown in Table II.

(nitrogen-containing heterocyclic compound)

The structure of the nitrogen-containing heterocyclic compounds R1 to R3 used in the production of the second protective film is shown below.

(acrylic compound)

<Modulation of Acrylic Compound A>

The preparation of the acrylic compound A is carried out by bulk polymerization in accordance with the polymerization method described in JP-A-2000-128911.

Specifically, in a flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, an inlet, and a reflux cooling tube, methyl acrylate (MMA) was introduced as a monomer, and nitrogen gas was introduced to replace the inside of the flask with nitrogen to obtain an acrylic compound.

Next, after the addition of thioglycerol, polymerization was carried out for 4 hours, and the contents were returned to room temperature, and phenylhydrazine 5 mass% tetrahydrofuran was added thereto. The liquid was stopped in an amount of 20 parts by mass. The contents were transferred to an evaporator, and tetrahydrofuran, residual monomers, and residual thioglycerol were removed under reduced pressure at 80 ° C to obtain polymethyl methacrylate, which was an acrylic compound having a number average molecular weight of 1,000 as determined by GPC. A.

<Modulation of Acrylic Compounds B and C>

According to the preparation method of the above-mentioned acrylic compound A, the following acrylic compound B and acrylic compound C were prepared.

Acrylic Compound A: Polymethyl methacrylate (number average molecular weight = 1000)

Acrylic Compound B: Polybutyl acrylate (quantitative average molecular weight = 1300)

Acrylic compound C: poly(methyl methacrylate / 2-ethylhexyl methacrylate (mole ratio 9/1) (number average molecular weight = 1600)

(Preparation of UV absorber)

The commercially available ultraviolet absorbers described below were used.

UV absorber A: Tinuvin 928 (manufactured by BASF Japan, benzotriazole compound)

UV absorber B: Tinuvin 109 (manufactured by BASF Japan, benzotriazole compound)

UV absorber C: Tinuvin 171 (manufactured by BASF Japan, benzotriazole compound)

UV absorber D: Tinuvin 326 (manufactured by BASF Japan, benzotriazole compound)

Ultraviolet absorber E: Tinuvin 460 (manufactured by BASF Japan, hydroxyphenyltriazine compound)

UV absorber F: Tinuvin 477 (manufactured by BASF Japan, hydroxyphenyl triazine compound)

UV absorber G: ADK Stab LA-F70 (made by Adeka, triazine compound)

(microparticles)

The fine particles A to C of the following fine-grained fine particles were used.

Microparticle A: Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd., hydrophobic fumed vermiculite, surface modified by dimethyldichloromethane, primary average particle diameter = about 16 nm)

Microparticle B: Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd., hydrophilic fumed vermiculite, no surface modification treatment, primary average particle diameter = about 12 nm)

Microparticle C: Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd., hydrophobic fumed vermiculite, surface modified by hexamethyldioxane, primary average particle diameter = about 7 nm)

[Production of Second Protective Film 1]

(modulation of fine particle dispersion 1)

Microparticles (Aerosil R812, manufactured by Japan Aerosil Co., Ltd.) 10 parts by mass

90 parts by weight of ethanol

The fine particles and ethanol were stirred and mixed in a dissolver for 50 minutes, and then dispersed in a Manton-Gaulin machine as a high-pressure disperser to prepare a fine particle dispersion 1.

(modulation of microparticle addition solution 1)

The fine particle dispersion liquid 1 prepared as described above was gradually added while thoroughly stirring the methylene chloride contained in the dissolution tank. Further, the secondary particles have a particle size of a predetermined size and are dispersed by a grinder. The fine particle addition liquid 1 was prepared by filtering this with Finemet NF manufactured by Nippon Seisaku Co., Ltd.

Methylene chloride 99 parts by mass

Microparticle dispersion 15 parts by mass

(modulation of glue)

Next, dichloromethane and ethanol as a solvent were added to the pressure dissolution tank. Then, the cellulose resin A was stirred while being placed in a pressure-dissolving tank containing a solvent. After heating, the mixture was completely dissolved while stirring, and the following additives were placed in a sealed dissolution vessel, and dissolved while stirring to prepare a dope. The added fine particles A are added as a solvent using one of the solvents added to the dope, and are added as the fine particle addition liquid 1 adjusted by the above method. The slurry was prepared by filtration using Angstrom filter paper No. 244 made of filter paper (strand).

<Composition of glue>

Solvent 1: dichloromethane 365 parts by mass

Solvent 2: ethanol 50 parts by mass

Cellulose resin A (cellulose acetate propionate, ethyl thiol substitution degree: 1.5, propyl thiol substitution degree: 0.9, total thiol substitution degree: 2.4, number average molecular weight (Mn) 640,000) 100 parts by mass

Sugar ester A 10 parts by mass

Polyester compound A 2 parts by mass

UV absorber A 2 parts by mass

Microparticle A (as a particulate solid component) 0.3 parts by mass

(film formation of the second protective film)

The second protective film 1 was produced using the solution casting apparatus having the configuration shown in Fig. 2 .

First, the dope was cast on a stainless steel belt support, and the solvent was evaporated in such a manner that the amount of residual solvent in the web formed by casting (casting) was 75% by mass.

Next, the mesh was peeled off from the stainless steel belt support at a peeling tension of 130 N/m. Then, using a tenter, the peeled web was extended to 1.3 times in the width direction. The amount of residual solvent at the start of stretching was 15% by mass. Furthermore, the tenter has an extension temperature of 160 °C.

Next, while drying the drying zone with a plurality of rolls, it was dried at 125 ° C for 5 minutes. Then, the film was cut into a width of 2 m, and knurling having a width of 10 mm and a height of 3 μm was applied to both ends of the film, and then wound on a core to prepare a second protective film 1 (dry film thickness: 30 μm, winding length: 5,200 m).

[Production of 2nd protective film 2~39]

In addition to the production of the second protective film 1, the additives of the cellulose resin, the sugar ester, the polyester compound, the nitrogen-containing heterocyclic compound, the acrylic compound, the ultraviolet absorber, the fine particles, and the solvent are changed to Table 3 and The second protective films 2 to 39 were produced in the same manner as in the combinations described in Table 4.

Hereinafter, Tables III and IV show the types and composition ratios (mass parts) of the respective additives of the second protective films 1 to 39.

<<Measurement of Characteristic Value of Second Protective Film>>

[Measurement of hysteresis value Ro and Rt]

Using an automatic birefringence meter Axo Scan Mueller Matrix Polarimeter (manufactured by AXO METRIX Co., Ltd.), the above-mentioned preparation was measured according to the following formula under the conditions of a measurement wavelength of 590 nm, a temperature of 23 ° C, and a relative humidity of 55% RH. The hysteresis value Ro of the in-plane direction of the second protective films 1 to 39 and the hysteresis value Rt of the film thickness direction.

Ro=(n _x -n _y )×d(nm)

Rt=((n _x +n _y )/2-n _z )×d(nm)

In the above formula, the refractive index in the direction of the slow axis in the plane of the n _x film; the refractive index in the direction perpendicular to the direction of the slow axis in the plane of the n _y film; n _z is the refraction perpendicular to the direction of the film face Rate; thickness of the d-type film (nm).

[Evaluation of UV transmittance]

For the second protective film produced above, an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name: V7100) was used, and the light transmittance at 380 nm (hereinafter also referred to as UV transmittance) was measured, and the following was performed. Benchmark, evaluation of UV transmittance was performed.

A: UV transmittance is less than 10%

B: UV transmittance is 10% or more and less than 25%

C: UV transmittance is 25% or more and less than 50%

D: UV transmittance is 50% or more and less than 80%

E: UV transmittance is 80% or more

[Measurement of film thickness]

The film thickness was measured in accordance with a usual method for the second protective film produced above.

The results obtained from the above are shown in Table V.

"The production of polarizing plates"

Using the first protective films PET1 to 4 and the second protective films 1 to 39 produced above, polarizing plates 1 to 88 were produced in accordance with the method described below.

[Production of Polarizing Plate 1]

(1. Production of polarizer)

While continuously transporting a long-length polyvinyl alcohol film having a thickness of 60 μm via a guide roller, it was immersed in a dye bath (30 ° C) in which iodine and potassium iodide were blended, and subjected to a dyeing treatment and a 2.5-fold stretching treatment. Next, in a acidic bath (60 ° C) to which boric acid and potassium iodide were added, a total of 5.0 times of elongation treatment and crosslinking treatment were applied, and the obtained 12 μm thick iodine-PVA-based polarizer was dried at 50 ° C in a dryer. It was dried for 30 minutes to obtain a polarizer having a moisture content of 4.9%.

(2. Modulation of water-based adhesive A)

The water-based adhesive A was prepared by mixing the components described below.

Pure water 100 parts by mass

Carboxyl modified polyvinyl alcohol (Kuraray Poval KL318, manufactured by Kuraray Co., Ltd.) 3.0 parts by mass

Water-soluble polyamine epoxy resin (30% solid solution, Sumirez Resin 650, manufactured by CHEMTEX) 1.5 parts by mass

(3. Treatment before the second protective film)

The second protective film 1 was immersed in a saponification treatment liquid (aqueous sodium hydroxide solution at 60 ° C, concentration: 10% by mass) for 30 seconds. Subsequently, the mixture was immersed twice in a water bath for 5 seconds, and then washed with water for 5 seconds, and then dried. The drying conditions were 70 ° C for 2 minutes.

Subsequently, the mixture was immersed in water at 30 ° C for 10 seconds to carry out swelling treatment, and then dried at 40 ° C for 53 seconds, and then subjected to the following bonding.

(4. Fit processing)

After the corona treatment is applied to each of the bonding surfaces of the first protective film PET1 and the second protective film 1, the water-based adhesive A is applied to each of the two surfaces of the polarizing mirror. Then, it was immediately dried in a hot air circulating dryer set at 80 ° C for 5 minutes to prepare a polarizing plate 1.

[Production of polarizer 2~88]

In the production of the polarizing plate 1 described above, the polarizing plates 2 to 88 were produced in the same manner except that the first protective film and the second protective film were changed to the combinations described in Tables 6 to 8.

In addition, the evaluation of the UV transmittance of the first protective film described in Tables 6 to 8 and the measurement of the film thickness were carried out in the same manner as the evaluation of the second protective film.

Evaluation of Polarizers

[Evaluation of yield (productive)]

Production of 10 days of continuous production of each of the polarizing plates produced above was measured The cleaning condition of the process and the yield of the polarizing plate (the ratio of the good product) were evaluated for productivity (benefit) according to the following criteria.

◎: The yield after continuous production for 10 consecutive days was 95% or more without performing the process cleaning.

○: The yield after continuous production for 10 consecutive days in the state where the process cleaning is not performed is 90% or more and less than 95%.

△: The yield after continuous production for 10 consecutive days in the state where the process cleaning is not performed is 85% or more and less than 90%.

×: The yield after continuous production for 10 consecutive days is less than 85% without performing the process cleaning.

The results obtained above are shown in Tables VI to VIII.

"Production of Liquid Crystal Display Devices"

Using the respective polarizing plates produced above, a liquid crystal display device (100) having the configuration shown in Fig. 4 was produced in accordance with the following method.

As the liquid crystal cell (101C), a VA mode liquid crystal cell having a thickness of 0.5 mm of two glass substrates (108A and 108B) and a liquid crystal layer (107) disposed therebetween was prepared. Then, the polarizing plates (101A and 101B) produced as described above are bonded to each other via the adhesive layer (106) so that the respective second protective films (105A and 105B) are on the liquid crystal cell (101C) side, thereby obtaining a liquid crystal display device. 1~88. In the bonding system, the absorption axis of the polarizer of the polarizing plate (101A shown in FIG. 4) on the visual recognition side and the absorption axis of the polarizer of the polarizing plate (101B shown in FIG. 4) on the backlight side are orthogonal to each other.

"Evaluation of Liquid Crystal Display Devices"

[Evaluation of durability of liquid crystal display device]

For each liquid crystal display device produced as described above, a super Xenon weathering tester SX120 (manufactured by SUGA Testing Co., Ltd.) was used from the visual recognition side of the liquid crystal display device, and the amount of light was 100 W/m ² at 50 ° C ‧65% RH Under the conditions, ultraviolet rays (calendering) were irradiated, and durability was evaluated in accordance with the following criteria.

○: deterioration of the liquid crystal display device was not observed even after 30 minutes of ultraviolet irradiation

△: deterioration of the liquid crystal display device was not observed in the ultraviolet irradiation time of 10 minutes or more and less than 30 minutes.

×: Even if the ultraviolet irradiation time is less than 10 minutes, there is deterioration of the liquid crystal display device, and it is difficult to visually recognize

The results obtained above are shown in Tables VI to VIII.

As is apparent from the above-described Tables VI to VIII, the polarizing plate of the present invention is excellent in productivity and high in yield with respect to conventional products. Further, by incorporating the polarizing plate of the present invention into a liquid crystal display device, it is understood that the deterioration of the liquid crystal cell due to the external environment is extremely effectively prevented even after long-term storage in a light irradiation (high temperature and high humidity) environment. .

Example 2

"Production of the second protective film: a cycloolefin film"

[Production of Second Protective Film 101]

(Synthesis of cycloolefin resin 1)

8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 ^2,5 .1 ^7,10 ]-3-dodecene (DNM) 75 mass%, dicyclopentadiene (DCP) 24 mass %, 2-norbornene 1% by mass, molecular weight modifier 1-hexene 9 parts, and toluene 200 parts were placed in a nitrogen-substituted reaction vessel and heated to 110 °C. 0.005 parts of triethylaluminum and 0.005 parts of methanol-modified WCl ₆ (anhydrous methanol: PhPOCl ₂ :WCl ₆ =103:630:427 mass ratio) were added thereto, and a polymer was obtained by a reaction for 1 hour. The solution of the obtained polymer was placed in an autoclave, and 200 parts of toluene was further added. Next, 0.006 part of RuHCl(CO)[P(C ₆ H ₅ )] ₃ as a hydrogenation catalyst was added, and after heating to 90 ° C, hydrogen gas was introduced into the reactor to bring the pressure to 10 MPa. Then, the pressure was maintained at 10 MPa, and the reaction was carried out at 165 ° C for 3 hours. After completion of the reaction, it was precipitated in a large amount of a methanol solution, and the precipitate was purified by reprecipitation using toluene and methanol to obtain a cyclic olefin resin 1 of a copolymer.

The weight average molecular weight (Mw) of the cycloolefin resin 1 system by gel permeation chromatography (GPC) = 7.2 × 10 ⁴ , molecular weight distribution (Mw / Mn) = 3.3, intrinsic viscosity (ηinh) = 0.59, glass transition temperature ( Tg) = 143 °C. In addition, the methoxycarbonyl group addition ratio of the copolymer P was determined by ¹³ C NMR measurement, and it was confirmed that 75% by mass of a monomer having a methoxycarbonyl group was added. The copolymer P obtained as described above is a cyclic olefin resin 1 which retains 75 mass% of a monomer having a methoxycarbonyl group as a hydrogen bond accepting group.

(modulation of fine particle dispersion)

Meteite granules (Aerosil R812 Japan Aerosil Co., Ltd.) 10% by mass

Methylene chloride 90% by mass

The mixture was stirred and mixed for 50 minutes in the dissolver, and then dispersed using a Manteolin disperser to prepare a fine particle dispersion.

(modulation of microparticle addition solution 1)

After the methylene chloride was placed in the dissolution tank, the methylene chloride was sufficiently stirred, and the fine particle dispersion liquid prepared as described above was gradually added in an amount of 50% by mass. Further, the secondary particles have a particle size which is a predetermined size and is dispersed in an attritor. The fine particle addition liquid 1 was prepared by filtering this with Finemet NF manufactured by Nippon Seisaku Co., Ltd.

(Modulation of glue A)

Stirring the above synthesized in a pressurized dissolution tank containing ethanol The cycloolefin resin P is charged at the same time. Then, the fine particle addition liquid was added so as to be added in the amount shown in Table 1, and then heated at the dissolution temperature shown in Table 1 for 4 hours, and completely dissolved while stirring. Then, it was filtered using an Augmentation filter paper No. 244 made of a filter paper (stock) to prepare a paste A. The composition of the glue A is shown below.

Cycloolefin resin 1 100% by mass

Tinuvin 928 3质量%

Dichloromethane 290% by mass

Microparticle addition liquid 27% by mass

Distilled water 1% by mass

Hindered phenolic compound (anti-aggregating agent A, IRGANOX 1076 (manufactured by BASF Japan)) 0.1% by mass

(film formation)

The previously prepared dope A was cast on a cast support made of stainless steel (support temperature: 22 ° C) using a belt casting apparatus. When the amount of the residual solvent in the paste A is approximately 20% by mass or less, the stripper is used to grasp both ends in the width direction of the film, and the residual solvent amount is 10% by mass or more, at 126. At a temperature of ° C, it was dried at 1.10 times in the longitudinal direction (MD direction) and 1.40 times in the width direction (TD direction) while being successively extended. Then, it was further dried by transporting at a roll of a heat treatment apparatus at 95 ° C for 30 to 40 minutes to prepare a second protective film 101 of a cycloolefin film. The thickness is 40 μm.

[Production of Second Protective Film 102]

In addition to the above-described production of the second protective film 101, the second protective film 102 was produced in the same manner except that the addition of Tinuvin 928 was not performed.

[Production of Second Protective Film 103]

In the production of the second protective film 101, in place of the cycloolefin resin 1, Arton G7810 manufactured by JSR Co., Ltd., and the addition amount of Tinuvin 928 was 3% by mass, and the film thickness was 20 μm, and the second protection was similarly produced. Membrane 103.

[Production of Second Protective Film 104]

In addition to the above-described second protective film 103, the second protective film 104 was produced in the same manner except that the addition of Tinuvin 928 was not performed.

[Production of Second Protective Film 105: Film Formation by Melt Casting Method]

The second protective film 105 was produced in accordance with the method described below.

(Modulation of Resin Composition 2)

100 parts of a dried polymer resin (manufactured by ZEON Co., Ltd., glass transition temperature: 123 ° C) and a benzotriazole-based ultraviolet absorber ("LA-31") were mixed by a biaxial extruder. 5.5 parts by ADEKA Co., Ltd., and then the mixture was poured into a hopper connected to an extruder, supplied to a uniaxial extruder, and melt-extruded to obtain a resin composition 2. The content of the ultraviolet absorber in the resin composition 2 was 5.2% by mass.

(Production of the front laminate 1 before extension)

The above-prepared resin composition 2 was placed in a hopper equipped with a double-helical 50 mm single-axis extruder equipped with a leaf-shaped polymer filter having a pore size of 3 μm (screw effective length L and screw diameter D) In the ratio L/D=32), the multi-manifold die having a surface roughness Ra of 0.1 μm supplied to the lip by the molten resin at an extruder outlet temperature of 280 ° C and a number of revolutions of the gear pump of the extruder of 10 rpm . On the other hand, a polymer resin having the same alicyclic structure as that used for the resin composition 2 was placed in a hopper equipped with a 50 mm single-axis extruder equipped with a leaf-shaped polymer filter having a pore size of 3 μm. (L/D = 32) The molten resin was supplied to the multi-manifold die at an extruder outlet temperature of 285 ° C and a number of revolutions of the gear pump of the extruder of 4 rpm. Next, each of the polymer resin having an alicyclic structure in a molten state, a resin composition in a molten state, and a polymer resin having an alicyclic structure in a molten state were discharged from a multi-manifold die at 280 ° C, and cast in a warp. The surface layer (5 μm) made of a polymer resin having an alicyclic structure - an intermediate layer (15 μm) made of the resin composition 2 was obtained by co-extrusion molding on a cooling roll adjusted to 150 ° C. A pre-extrusion laminate 1 having a width of 1400 mm and a thickness of 25 μm composed of two types of three layers of a surface layer (5 μm) made of a polymer resin having an alicyclic structure. Further, the amount of air gap was 50 mm, and edge pinning was employed as a method of casting a film in a molten state on a cooling roll. Trim the ends of the laminate by 50mm each. Next, at a temperature of 126 ° C, it is 1.10 times in the longitudinal direction (MD direction) and 1.40 times in the width direction (TD direction). The extension is dry on one side. Then, it was further dried by transporting at a roll of a heat treatment apparatus at 95 ° C for 30 to 40 minutes to prepare a second protective film 105 of a cycloolefin film. The thickness is 30 μm.

[Production of Second Protective Film 106]

The second protective film 106 was produced in the same manner as in the production of the second protective film 105 except that the benzotriazole-based ultraviolet absorber ("LA-31", manufactured by ADEKA CORPORATION) was not added.

[Production of the second protective film 107 to 112]

In the production of the second protective films 101 to 106, the stretching ratios in the MD direction and the TD direction in the respective extending steps are appropriately changed, and the second protective film is produced in the same manner as in the case of Ro and Rt described in Table IX. 107~112.

"The production of polarizing plates"

Using the first protective films PET2 to PET4 produced in Example 1 and the above-described second protective films 101 to 112, polarizing plates 101 to 120 were produced in accordance with the following methods.

[Production of Polarizing Plate 101]

1) Production of polarizer

While continuously transporting a long-length polyvinyl alcohol film having a thickness of 60 μm via a guide roller, it is immersed in a dye bath (30 ° C) in which iodine and potassium iodide are blended, and is administered. After the dyeing treatment and the 2.5-fold extension treatment, a total of 5 times of extension treatment and crosslinking treatment were applied in an acidic bath (60 ° C) to which boric acid and potassium iodide were added, and the obtained 12 μm-thick iodine-PVA-based polarized light was obtained. The mirror was dried in a dryer at 50 ° C for 30 minutes to obtain a polarizer having a moisture content of 4.9%.

2) Modulation of ultraviolet curing type adhesive B

The following components were mixed to prepare a liquid ultraviolet curable adhesive.

40 parts by mass of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate

Bisphenol A type epoxy resin 60 parts by mass

Diphenyl[4-(phenylthio)phenyl]phosphonium hexafluoroantimonate (cationic polymerization initiator) 4.0 parts by mass

3) Lamination and polarizing plate production

After the corona treatment was applied to the bonding surface of the first protective film PET4, the ultraviolet curable adhesive B prepared as described above was applied to a thickness of 3 μm by a coating device having a sealing blade. Moreover, after applying a corona treatment to the bonding surface of the second protective film 101, the ultraviolet curable adhesive B was applied in the same thickness to a thickness of 3 μm.

After applying the ultraviolet curable adhesive to the first protective film PET4 and the second protective film 101, the coated surface of the ultraviolet curable adhesive B is applied to the coated polarizer by the bonding roller. The first protective film PET4 is bonded to one surface, and the second protective film 101 is bonded to the other surface. Then, the metal halide lamp was irradiated from the first protective film side so that the integrated light amount at a wavelength of 280 to 320 nm became 320 mJ/cm ² at a linear velocity of 20 m/min, and the adhesive on both surfaces was cured to obtain a polarizing plate. 101.

[Production of polarizing plate 102-120]

In the production of the polarizing plate 101 described above, the polarizing plates 102 to 120 were produced in the same manner except that the first protective film and the second protective film were changed to the combinations described in Table IX.

"Production of Liquid Crystal Display Devices"

Using the polarizing plate produced above, a liquid crystal display device was produced in accordance with the method described below.

As the liquid crystal cell, a VA mode liquid crystal cell having a thickness of 0.5 mm of two glass substrates and a liquid crystal layer disposed therebetween was prepared. Then, the respective polarizing plates 101 thus produced are bonded to each other via the adhesive layer so that the respective second protective films are on the liquid crystal cell side, thereby obtaining liquid crystal display devices 101 to 120. In the bonding system, the absorption axis of the polarizer of the polarizing plate (101A shown in FIG. 4) on the visual recognition side and the absorption axis of the polarizer of the polarizing plate (101B shown in FIG. 4) on the backlight side are orthogonal to each other.

"Evaluation of Liquid Crystal Display Devices and Polarizers"

The durability and the yield were evaluated in the same manner as in the method described in Example 1, and the results obtained are shown in Table IX.

As is apparent from the above Table IX, the polarizing plate of the present invention is excellent in productivity and high in yield with respect to conventional products. Further, by incorporating the polarizing plate of the present invention into a VA liquid crystal display device, it is understood that the liquid crystal cell due to the external environment is extremely effectively prevented even after long-term storage in a light irradiation (high temperature and high humidity) environment. Deterioration.

[Industry use possibility]

The polarizing plate of the present invention can be used for liquid crystal display devices of various driving methods such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, and OCB. In particular, it can be suitably used for a crystal display device.

51‧‧‧Polar plate

52‧‧‧1st protective film

53‧‧‧ polarizer

54‧‧‧2nd protective film

55‧‧‧UV hardened resin layer

Claims (11)

A polarizing plate which is a polarizing plate which is formed by a first protective film, a polarizing mirror, and a second protective film from a visual recognition side, wherein the first protective film has super-birefringence in a plane. And a polyester film having a light transmittance of 380 nm of 50% or more, wherein the second protective film is a light transmissive film having a light transmittance of less than 50% at 380 nm, and the second protective film is as follows The hysteresis value Ro(nm) in the in-plane of the film defined by the formula (i) satisfies the condition defined by the following formula (iii), and the hysteresis value Rt (nm) in the film thickness direction defined by the following formula (ii) is satisfied. The condition specified by the following formula (iv); (i) Ro = (n _{x -} n _y ) × d (ii) Rt = ((n _x + n _y ) / 2 - n _z ) × d (iii) 40 ≦Ro≦300 (iv) 100 ≦ Rt ≦ 400 [wherein, the refractive index of the slow phase axis in the plane of the n _x film, and the refractive index of the n _y film in the direction perpendicular to the direction of the slow axis; n _z is a refractive index perpendicular to the direction of the film surface; thickness (nm) of the d-type film]. The polarizing plate of claim 1, wherein the second protective film contains a cellulose resin. The polarizing plate of claim 1, wherein the second protective film contains a cycloolefin resin. The polarizing plate according to any one of claims 1 to 3, wherein the second protective film contains at least one ester selected from the group consisting of a sugar ester, a polyester compound, and a polyol ester. The polarizing plate according to any one of claims 1 to 4, wherein the second protective film contains at least one ultraviolet absorber selected from the group consisting of a benzotriazole-based compound and a triazine-based compound. The polarizing plate according to any one of claims 1 to 5, wherein the first protective film has an ultraviolet curable resin layer. A method for producing a polarizing plate, which is a method for producing a polarizing plate according to any one of claims 1 to 6, characterized in that the light transmittance at 380 nm is obtained by a melt casting method. The second protective film that does not have a light transmittance of 50% is formed into a film. A method for producing a polarizing plate, which is a method for producing a polarizing plate according to any one of claims 1 to 6, characterized in that the light transmittance at 380 nm is obtained by a solution casting method. The second protective film that does not have a light transmittance of 50% is formed into a film. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 6 on the surface of the liquid crystal cell (front side). A liquid crystal display device comprising a polarizing plate according to any one of claims 1 to 6 on each of a surface of a liquid crystal cell (front side) and a non-visual side (rear side). The liquid crystal display device of claim 9 or 10, wherein the glass substrate of the liquid crystal cell has a thickness of 0.3 to 0.7 mm.