TWI437323B - Liquid crystal display device - Google Patents

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly to a directional field switching mode type in which the visibility of the viewing angle, the color shift, or the sharpness when viewed from the oblique direction is improved, and the front contrast is improved. A liquid crystal display device (hereinafter referred to as an IPS mode liquid crystal display device).

The horizontal electric field switching mode liquid crystal display device has excellent color tone, contrast, viewing angle, and the like with respect to the liquid crystal mode of other liquid crystal display devices, for example, in the vertical alignment mode (VA, MVA, PVA, etc.). It has excellent display performance such as a viewing angle, and has an excellent effect of less variation in luminance due to a viewing angle and a small drop in response speed of a halftone. Therefore, it is generally referred to as an IPS (In Plane Switching) mode liquid crystal display device. (IPS mode TV, etc.) is actively provided in the market. As the IPS mode liquid crystal display device, in addition to the so-called IPS mode, an FFS (Fringe Field Switch) mode or an FLC (Strong Dielectric Liquid Crystal) mode can be cited.

However, although the IPS mode has characteristics of a wide viewing angle in the vertical direction and the horizontal direction, there is also a problem that the viewing angle from the oblique direction is narrow.

Therefore, as such a viewing angle compensation method, a method of using a one-half wave plate is proposed (for example, refer to Patent Document 1).

But make a 1/1 wavelength plate because of the need to make the stretched film The troublesome operation of heat shrinkage, coupled with the production of a shrink sheet, requires time and cost, and causes a problem of a decrease in transmittance or a thick film of a polarizing plate. Therefore, in such a method, it is difficult to achieve a polarizing plate with a roll to roll, and a problem of unevenness due to heat shrinkage and a low degree of axial accuracy are problems of the retardation film.

For such a problem, compensation by a simple stretched film is also conceivable (for example, refer to Patent Document 2), which proposes to use an optical film having a negative 1-axis property and an optical film having nx>ny>nz. The laminated retardation film, in this case, the negative one-axis property means -0.4 < Nz < 0.1, and has an optical axis in the plane.

Further, it is proposed that the retardation value Ro in the plane is Ro<100 nm, and the retardation value Rth in the thickness direction is a phase difference layer of Rth=50 to 200 nm, and the layer having the refractive index anisotropy is negative and the optical axis is held in the plane. Lamination (for example, refer to Patent Document 3).

However, in such a configuration, although a certain degree of viewing angle is improved as compared with the case of the non-resection film, the improvement of the viewing angle in the oblique direction is insufficient, and the reproducibility of the black display due to light leakage or the like is caused. There is still a problem with the clarity.

Moreover, such documents do not specifically address the high positive contrasts required to improve large-screen TVs in recent years.

[Patent Document 1] JP-A-2006-293108 (Patent Document 3) JP-A-2005-309382

Therefore, an object of the present invention is to provide a lateral electric field switching mode liquid crystal display device (hereinafter referred to as an IPS mode type) in which the viewing angle when viewed from a slope direction, the reproducibility of black display, or the sharpness is improved, and the front contrast is improved. Liquid crystal display device).

The above problems of the present invention are achieved by the following constitution.

1. A liquid crystal display device characterized in that a first polarizer, a first substrate, a liquid crystal layer, a second substrate, and a second polarizer are disposed in this order, and a first polarizer is disposed between the first polarizer and the first substrate. 1 retardation layer and second retardation layer, liquid crystal display system in which the liquid crystal molecules of the liquid crystal layer are aligned in parallel with respect to the surfaces of the first substrate and the second substrate in black display, and the first retardation layer is negative In the biaxiality, the in-plane hysteresis value Ro of the second retardation layer is 0 ≦ Ro ≦ 50 nm, and the hysteresis value Rth in the thickness direction of the second retardation layer is 50 ≦ Rth ≦ 300 nm, and the absorption of the first polarizer is The axis is orthogonal to the slow axis direction of the liquid crystal layer in the black display, and the first retardation layer and the second retardation layer are connected to the first retardation layer. When the first retardation side is near, the in-plane slow axis of the first retardation layer is parallel to the absorption axis of the first polarizer, and the second retardation layer is different from the second retardation layer in the first retardation layer and the second retardation layer. When the first polarizer side is approached, the in-plane slow axis of the first retardation layer is orthogonal to the absorption axis of the first polarizer.

Ro=(nx-ny)×d Rth={(nx+ny)/2-nz}×d (where nx is the refractive index in the direction of the slow phase axis in the phase difference layer, and ny is the phase in the phase difference layer) The refractive index in the axial direction, nz is the refractive index in the thickness direction of the phase difference layer, and d is the thickness (nm) of the phase difference layer.

2. The liquid crystal display device according to the above 1, wherein Nz defined by the following formula in the first retardation layer is -1.5 ≦Nz < -0.5, and Ro is 50 ≦Ro ≦ 300 nm.

Nz=(nx-nz)/(nx-ny) (wherein nx is the refractive index in the direction of the slow axis in the phase difference layer, ny is the refractive index in the direction of the phase axis in the phase difference layer, and nz is the phase The refractive index in the thickness direction of the difference layer.)

3. The liquid crystal display device according to the above aspect, wherein the third retardation layer is disposed between the second polarizer and the second substrate, and the hysteresis value of the third retardation layer is 0 ≦ Ro ≦ 5 nm and conforms to 0. ≦|Rth|<40nm.

4. The liquid crystal display device according to any one of the preceding claims, wherein the second retardation layer is made of a cellulose ester resin.

In the liquid crystal display device according to any one of the above aspects, the first retardation layer is made of a styrene resin or a lanthanum resin.

According to the present invention, it is possible to provide a lateral electric field switching mode liquid crystal display device (hereinafter referred to as an IPS mode liquid crystal display) in which the viewing angle when viewed from the oblique direction, the reproducibility of the black display, or the sharpness, and the like, and the front contrast are improved. Device).

[Best Mode for Carrying Out the Invention]

The best mode for carrying out the invention will be described in detail below, and the invention is not limited thereto.

First, the term "phase difference layer" as used in the present invention is defined as that the light of the backlight or the like is once linearly polarized by the polarizing plate of the first sheet, and is polarized by a liquid crystal layer or the like, and is again converted into a straight line. The functional layer, substrate, or film of the so-called optical compensation function of polarized light. Therefore, in addition to the case where the substrate or the film itself has an optical compensation function, it also includes a substrate or a film which is coated with a material having a phase difference function, or which is vapor-deposited to impart an optical compensation function.

The present invention is preferably a retardation film from the viewpoint of processing suitability and ease of handling of the retardation layer, and the retardation layer and the retardation film may be treated synonymously in the present specification.

As a result of intensive studies in view of the above-described problems, the inventors of the present invention have a biaxial phase difference layer having no negative optical axis and an in-plane retardation in an IPS mode liquid crystal display device. The phase difference layer is superimposed in a manner orthogonal to the respective slow phase axes, and a new viewpoint of improving the viewing angle and the front contrast is found, and the present invention has been completed.

That is, by laminating layers having different optical characteristics, it is possible to change the polarization state which is impossible for the single layer of the phase difference layer. At this time, if the lamination does not have the phase of the in-plane phase difference In the case of the difference layer, the polarization conversion can be achieved only in the thickness direction component, and the phase difference layer having the in-plane phase difference can be specifically laminated, and the polarization state can be changed not only in the thickness direction but also in the in-plane direction.

The visibility and frontal contrast of the reproducibility and the sharpness of the black display when viewed from the oblique direction are considered to be affected by the polarization state of both the thickness direction and the in-plane direction, so the phase of the phase difference in the laminated plane is affected. The difference layer is estimated to be improved in visibility when viewed in the direction of the slope of the polarization state of both the in-plane and the thickness, and the front contrast is greatly improved. In the case where the polarization state converted by the first retardation layer and the second retardation layer is not changed, the phase difference of the third retardation layer to be described later is preferably as small as possible.

Further, when a negative retardation layer is formed by stretching of the resin, by performing biaxial stretching sequentially or simultaneously, a layer having better planarity and no unevenness in phase difference can be produced, and therefore, it is more than one axis extending by the free end. A liquid crystal display device having a phase difference layer having an optical axis or a thickness alignment retardation layer obtained by heat shrinkage in the obtained surface has more excellent visibility.

Therefore, the liquid crystal display device of the present invention is characterized by the first polarized light. The first substrate, the liquid crystal layer, and the second substrate are arranged in this order, and the first retardation layer and the second retardation layer are disposed between the first polarizer and the first substrate, and the liquid crystal layer is disposed during black display. In the liquid crystal display device in which the liquid crystal molecules are aligned in parallel with the surfaces of the first substrate and the second substrate, the first retardation layer is negatively biaxial, and the second retardation layer is defined by the following formula. The in-plane hysteresis value Ro is 0 ≦ Ro ≦ 50 nm, and the hysteresis value Rth in the thickness direction of the second retardation layer is 50 ≦ Rth ≦ 300 nm, and the absorption axis of the first polarizer is delayed from the liquid crystal layer at the time of black display. When the axial direction is orthogonal, in the first retardation layer and the second retardation layer, when the first retardation layer is closer to the first polarizer side, the slow axis of the first retardation layer and the absorption axis of the first polarizer are In the parallel, in the first retardation layer and the second retardation layer, when the second retardation layer is closer to the first polarizer side, the slow axis of the first retardation layer is orthogonal to the absorption axis of the first polarizer.

In the present invention, the first retardation layer has a negative biaxial property, and means that Nz defined by the following formula corresponds to Nz < -0.5, preferably -1.5 ≦ Nz < -0.5, more preferably -1.3. The range of ≦Nz≦-0.8 does not have an optical axis in the plane, and Ro is preferably in the range of 50 to 300 nm.

Ro=(nx-ny)×d Rth={(nx+ny)/2-nz}×d Nz=(nx-nz)/(nx-ny) (wherein nx is the refractive index in the direction of the slow phase axis in the phase difference layer, and ny is the phase difference level The refractive index in the direction of the in-phase axis, nz is the refractive index in the thickness direction of the phase difference layer, and d is the thickness (nm) of the phase difference layer.

In order to impart negative biaxiality to the first retardation layer, a resin having a negative dielectric anisotropy may be formed, for example, a styrene resin or a fluorene-based resin in a single film, by simultaneous or It is preferable to carry out the biaxial stretching production successively, or to apply the resin to another resin substrate, and then dry and fix the layer to form the layer, and to laminate the other resin substrate and the resin. Give negative biaxiality. In this case, the second retardation layer described above can be used for the other resin substrate.

In order to set the hysteresis value of the second retardation layer to the above numerical range, it is preferred that the second retardation layer is subjected to one-axis or two-axis stretching treatment in a heat-treated state, and further, the retardation layer contains a cellulose ester. In the case of stretching after the heat treatment, in order to reduce the residual strain as much as possible, in the range of about 0.1 to 1.5 times in the range of ±10 ° C of the glass transition point of the cellulose ester, in the direction orthogonal to the conveyance direction or the conveyance direction. In the state in which the amount of the residual solvent is from 2 to 100% by mass, the film is stretched by 1.1 to 1.7 times in a direction orthogonal to the conveyance direction or the conveyance direction. .

Further, the in-plane slow axis of the second retardation layer is oriented in the direction orthogonal to the conveyance direction, and the unevenness in the control plane is preferable, so that it is precisely controlled The balance between the extension temperature and the extension ratio is controlled, and the extension portion (the clip of the tenter, etc.) is controlled independently on both sides of the phase difference layer, which can still be adjusted by adjusting the position of the clip and the stress extension temperature with respect to the clip. Achieved with extension ratio.

Further, in the liquid crystal display device of the present invention, the third retardation layer is disposed between the second substrate and the second polarizer, and the hysteresis value of the third retardation layer is 0 ≦ Ro ≦ 5 nm and conforms to 0 ≦ | Rth | <40 nm is a preferred embodiment for the purpose of improving the viewing angle or the improvement of the front side contrast, and particularly preferably in accordance with 0 ≦ | Rth | < 10 nm.

In other words, by controlling the hysteresis values of the first retardation layer and the second retardation layer to a specific range and reducing the hysteresis values Ro and Rth of the third retardation layer, the field of view of the IPS mode liquid crystal display device is removed. In addition to the angular expansion effect, plus a significant increase in contrast.

In order to set the hysteresis value of the third retardation layer to the above numerical range, when the main component of the third retardation layer is a cellulose ester, it is produced by melt film formation, or a solution is formed by a solution, and a glass transition point or more is formed in the middle. It is preferred to maintain the temperature for more than 15 seconds, or to add a material or additive having a birefringence expressive property opposite to that of the cellulose ester. Further, in the case of a cycloolefin-based film, it is preferred to use it directly without stretching the film produced by the melt or solution casting.

Hereinafter, the present invention will be described in detail with reference to each element.

<Measurement of hysteresis value>

Determination of the hysteresis value associated with the present invention, one of which is to use the prince KOBRA21ADH manufactured by the test machine was used to measure the third-order refractive index at a wavelength of 590 nm in the environment of 23 ° C and 55% RH to obtain the refractive index nx, ny, and nz, and then the above-mentioned Ro, Rth. In the formula, the average value of each refractive index is substituted and calculated.

In the present invention, the retardation value in the thickness direction of the phase difference layer is a sample having a negative value. When the hysteresis value is calculated, the in-plane axis of the phase difference layer is an oblique axis, and the hysteresis value at the time of tilting at 40 degrees is measured and used. For calculation.

<Configuration of polarizing plate and liquid crystal display device>

The configuration of the polarizing plate and the liquid crystal display device of the present invention will be described using a diagram.

Fig. 1 is a configuration of a polarizing plate and a liquid crystal display device according to claim 1 of the patent application.

The first polarizer 1 is disposed in the order of the first polarizer 1, the second retardation layer 3, the first retardation layer 2, the first substrate 4, the liquid crystal layer 5, the second substrate 6, and the second polarizer 8. The absorption axis 11 is orthogonal to the slow axis direction 14 of the liquid crystal layer 5 during black display, and the absorption axis 11 of the first polarizer 1 is parallel to the slow axis 13 of the second retardation layer 3, and the first phase difference is The retardation axis 12 of the layer 2 is orthogonal to the absorption axis 11 of the first polarizer, and the third retardation layer 7 related to the third item of the patent application is preferably disposed between the second substrate 6 and the second polarizer 8. The absorption axis 15 of the second polarizer 8 is parallel to the slow axis direction 14 of the liquid crystal layer 5 at the time of black display, and the position of the backlight (BL) may be either the first polarization sub-side or the second polarization sub-side.

Figure 2 is a polarizing plate and liquid crystal display related to the first item of the patent application scope Other components of the device.

The first polarizer 1, the first retardation layer 2, the second retardation layer 3, the first substrate 4, the liquid crystal layer 5, the second substrate 6, and the second polarizer 8 are disposed on the viewing side, and the first polarizer The absorption axis 11 of 1 is orthogonal to the slow axis direction 14 of the liquid crystal layer 5 at the time of black display, and the absorption axis 11 of the first polarizer 1 is parallel to the slow axis 12 of the first retardation layer 2, and the second phase difference is The slow axis 13 of the layer 3 is orthogonal to the absorption axis 11 of the first polarizer 1.

Further, between the second substrate 6 and the second polarizer 8, the third retardation layer 7 according to the third aspect of the patent application is preferably disposed, and the position of the backlight (BL) is on the first polarizer side or the second polarizer. Available on either side of the side.

In this specification, the meaning of "parallel" and "straight" means that the range is not within a strict angle of ±10°, and the error of this range and the strict angle is preferably less than ±5°. ±2° is better.

With respect to the lamination order of the first retardation layer and the second retardation layer, for example, when the second retardation layer made of the cellulose resin is bonded to the first polarizer, it is easier to follow the PVA polarizer. Because it can be laminated by existing steps, it is highly productive.

The first polarizer and the second polarizer can be produced by a general method, and the polarizer is a light-transmitting element that passes only a polarized surface in a certain direction, and a known polarized light is known as a polyvinyl alcohol-based polarizing film. This is a case where the polyvinyl alcohol-based film is subjected to iodine dyeing and subjected to dichroic dyeing. The polarizer is formed by forming a film by using an aqueous solution of polyvinyl alcohol, performing dyeing after one-axis stretching, or performing one-axis stretching after dyeing, preferably Persistent treatment with boron compounds.

Usually, the photon is held on both sides by a TAC film as a protective layer, and the back side of the TAC film is alkalized, and at least one surface of the polarizer produced by immersion stretching in the iodine solution is used completely. The alkalized polyvinyl alcohol aqueous solution is preferably bonded, and the TAC film may be used on the other surface, and other polarizing plates may be used to protect the film. Commercially available cellulose ester films (for example, Konicaminolta tak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4UE, KC8UY, KC4UY, KC12UR, KC4FR, above Konica Minolta Opto) are also preferred users. .

In the configuration of the present invention, both the first polarizer and the second polarizer are held by two TAC films, and the first retardation layer, the second retardation layer, and the third retardation layer may be bonded via the adhesive layer. However, it is preferable that the first retardation layer or the second retardation layer is directly bonded to the first polarizer, and the third retardation layer is directly bonded to the second polarizer, which is preferable because of thinning and member reduction.

By incorporating the above-described polarizing plate of the present invention into a liquid crystal display device, it is possible to produce a liquid crystal display device of the present invention which is excellent in visibility.

The polarizing plate of the present invention is directly bonded to the first substrate and the second substrate which hold the liquid crystal layer. However, since the substrate of the liquid crystal cell is required to have high planarity and smoothness, a glass substrate having translucency is mainly used. When the desired planarity and smoothness are used, it is not only a glass substrate but also a plastic substrate. When a plastic substrate is used, it is easy to make the thickness of the substrate 0.2 mm or less, so that the display element can be made extremely thin and lightweight. In addition, because the substrate is thin, it can be displayed without a wide viewing angle of double shadow. The first substrate and the second substrate may be the same material or different.

The polarizing plate of the present invention can be used for an IPS mode liquid crystal display device or an IPS mode liquid crystal display device, characterized in that liquid crystal molecules of the liquid crystal layer are aligned in parallel with respect to the surface of the pair of substrates in black display, and are not in the IPS mode. Examples include an FFS (Fringe Field Switch) mode and an FLC (Strong Dielectric Liquid Crystal) mode.

The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 and 2 . Other members may be included. For example, a color filter may be disposed between the liquid crystal layer and the polarizer, and an anti-reflection treatment or a hard coating may be applied to the surface of the protective film of the polarizer. Further, a conductive member may be used for imparting conductivity to the constituent member, and when used as a transmissive type, a backlight using a cold cathode or a hot cathode calender tube, or a light emitting diode, a field emission element, or an electroluminescence element as a light source may be used. It is disposed on the back surface. In this case, the backlight can be disposed on the upper side of FIG. 1 and FIG. 2 or on the lower side. In addition, a reflective polarizing plate or a diffusing plate, a prism sheet or a light guide plate can be disposed between the liquid crystal layer and the backlight. Further, as described above, the liquid crystal display device of the present invention may be of a reflective type. In the case of the related art, only one sheet may be disposed on the observation side, and a reflective film may be disposed on the inner surface of the liquid crystal cell back surface or the lower substrate of the liquid crystal cell. It is of course also possible to set the front light to the liquid crystal cell observation side before using the aforementioned light source.

In particular, the liquid crystal display device of the present invention has a screen size of 30 inches or more, and particularly a large screen of 30 inches to 54 inches, which has a high contrast, and particularly suppresses a change in color tone due to a viewing angle, even for a long time of appreciation. The eyes will not fatigue.

<phase difference layer> (first phase difference layer)

The first retardation layer according to the present invention is characterized in that it has a negative biaxiality, and Nz defined by the above formula is Nz < -0.5, preferably the hysteresis value Ro of the first retardation layer is 50 ≦ Ro≦. In the range of 300 nm, the Nz represented by the above formula is -1.5 ≦Nz < -0.5, and preferably Ro is in the range of 100 ≦ Ro ≦ 200 nm, and Nz is in the range of -1.3 ≦ Nz ≦ - 0.8.

It is preferable to impart a negative biaxiality to the first retardation layer of the present invention, and to use a resin having a negative dielectric anisotropy, and it is particularly preferable to use a styrene resin or a fluorene-based resin.

Styrene-based resin, which can be roughly divided into individual polymers of styrene or styrene derivatives; copolymer of styrene or styrene derivatives with other monomers; from styrene or styrene derivatives and other monomers The resulting grafted copolymer; and mixtures of such polymers.

Examples of the individual polymer of styrene or a derivative thereof include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, and o-nitrobenzene. A separate polymer of ethylene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, and 2,5-dichlorostyrene. Examples of the copolymer of styrene or a styrene derivative with other monomers include a styrene/acrylonitrile copolymer, a styrene/methacrylonitrile copolymer, and a styrene/methyl methacrylate copolymerization. , styrene/ethyl methacrylate copolymer, styrene/α-chloroacrylonitrile copolymer, styrene/methyl acrylate copolymer, styrene/ethyl acrylate copolymer, styrene/acrylic acid Butyl ester copolymer, styrene/acrylic acid copolymer, styrene/methacrylic acid copolymer, styrene/butadiene copolymer, styrene/isoprene copolymer, styrene/Malay Anhydride copolymer, styrene/itaconic acid copolymer, styrene/vinylcarbazole copolymer, styrene/N-phenyl acrylamide copolymer, styrene/vinylpyridine copolymer, styrene /vinylnaphthalene copolymer, α-methylstyrene/acrylonitrile copolymer, α-methylstyrene/methacrylonitrile copolymer, α-methylstyrene/vinyl acetate copolymer, benzene Ethylene/α-methylstyrene/acrylonitrile copolymer, styrene/α-methylstyrene/methyl methacrylate copolymer, and styrene/styrene derivative copolymer.

Examples of the graft copolymer include the following (p-1 to p-17), but (A) indicates a dry polymer (may also be a block copolymer), and (B) indicates a branch portion ( The graft portion), in addition to the following amount ratio, represents the mass ratio.

[p-1]: (A1)/(B1)=10/90 (A1) Styrene/butadiene copolymer (20/80) (B1) Styrene/Acrylonitrile/α-methylstyrene (60/20/20) [p-2]: (A1)/(B1)=5/95 [p-3]: (A1) / (B2) = 10/90 (B2) styrene/acrylonitrile (80/20) [p-4]: (A1)/(B2)=7/93 [p-5]:(A2)/(B3)=12.5/87.5 (A2) styrene/butadiene copolymer (50/50) (B3) Styrene/Acrylonitrile (75/25) [p-6]:(A2)/(B4)=15/85 (B4) styrene/acrylonitrile/α-methylstyrene (60/30/10) [p-7]: (A2) / (B4) = 10/90 [p-8]: (A2) / (B3) = 10/90 [p-9]:(A3)/(B5)=5/95 (A3) polybutadiene (B5) Styrene/Acrylonitrile (70/30) [p-10]:(A3)/(B6)=10/90 (B6) Styrene/Acrylonitrile/Methylacrylonitrile (75/15/10) [p-11]:(A2)/(B7)=12/88 (B7) styrene [p-12]:(A4)/(B8)=10/90 (A4) Styrene/Butadiene Copolymer (23/77) (B8) Styrene/Methyl Methacrylate/Acrylonitrile (70/10/20) [p-13]: (A5)/(B9)=10/90 (A5) polyisoprene (B9) Styrene/t-butylstyrene (70/30) [p-14]:(A6)/(B2)=10/90 (A6) Acrylonitrile/butadiene copolymer (50/50) [p-15]:(A7)/(B1)=12/88 (A7) Acrylonitrile/Butadiene Copolymer (25/75) [p-16]:(A8)/(B10)=10/90 (A8) ethyl acrylate/butadiene copolymer (50/50) (B10) Styrene/Methyl Methacrylate (80/20) [p-17]:(A9)/(B11)=15/85 (A9) Ethyl acrylate/styrene/butadiene copolymer (40/30/30) (B11) Styrene/methacrylonitrile (75/25)

The styrene-based resin is disclosed in JP-A-4-97322 and JP-A-6-67169.

The retardation layer having a negative biaxiality optically can be obtained, for example, by simultaneously or sequentially stretching the styrene-based polymer having a negative dielectric anisotropy, and the retardation layer is simultaneously provided. It is preferable that the one-side direction is one-axis extending while holding the holder, and further, by applying the polymer to a transparent substrate, drying and fixing, it is preferable to form the coating material and the substrate. It is also better to extend together.

Further, in the present invention, it is also preferable to use a lanthanoid resin as the retardation layer, and in particular, since the segment having the ruthenium skeleton can be negative optical anisotropy, the polycarbonate having the ruthenium skeleton and the ruthenium skeleton are used. a polycarbonate-based copolymer, a polyester having an anthracene skeleton, a polyester-based copolymer having an anthracene skeleton, a polyester carbonate having an anthracene skeleton, a polyester carbonate-based copolymer having an anthracene skeleton, and having a fluorene A polyarylate of a skeleton, a polyarylate-based copolymer having an anthracene skeleton, and the like are preferred.

Similarly to the styrene-based resin, a retardation layer having a negative biaxiality optically can be simultaneously or biaxially stretched by a polymer such as the above-described fluorene-based resin having a negative dielectric anisotropy. It is formed by coating on a base material.

(Method of manufacturing phase difference layer)

Next, a method for producing the first, second, and third retardation layers according to the present invention will be described by taking a particularly good retardation film as an example.

The retardation layer used in the present invention is preferably a retardation film produced by a solution casting method or a melt casting method.

The production of the retardation film used in the present invention is carried out by dissolving the above-mentioned resin or a cellulose ester and an additive described later in a solvent to prepare a dope, and casting the dope on an infinitely moving endless metal support. a step of drying the casted paste into a web, a step of peeling from the metal support, a step of stretching or width maintaining, a step of further drying, and a step of winding the processed film And proceed.

The step of preparing the dope, the concentration of the resin or the cellulose ester in the dope, the drying load after the concentrated one is cast to the metal support can be preferably lowered, and the concentration of the resin or the cellulose ester is too thick to be filtered. The load increases and the filtering accuracy deteriorates. The concentration is preferably from 10 to 35% by mass, more preferably from 15 to 25% by mass.

The solvent to be used for the sizing may be used singly or in combination of two or more kinds, and a good solvent or a solvent of a cellulose ester or a weak solvent may be used, and it is preferable from the viewpoint of production efficiency, and one of the good solvents is It is preferable from the viewpoint of solubility of a resin or a cellulose ester.

The preferred range of the mixing ratio of the good solvent to the weak solvent is 70 to 98% by mass of the good solvent and 2 to 30% by mass of the weak solvent. The solvent or weak solvent is used alone to dissolve the resin used or Cellulose ester is defined as A good solvent, which is used alone or swelled or undissolved, is defined as a weak solvent.

Therefore, for example, depending on the average degree of acetylation (degree of substitution) of the cellulose ester, the good solvent and the weak solvent may be changed, for example, when acetone is used as the solvent, the cellulose ester of the cellulose ester (acetamyl substitution) Degree 2.4), cellulose acetate propionate became a good solvent, and cellulose acetate (acetylation degree of ethylene 2.8) became a weak solvent.

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

Further, the weak solvent used in the present invention is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone or the like can be preferably used. Further, it is preferable that the water in the dope is contained in an amount of 0.01 to 2% by mass, and the solvent used for dissolving the resin or the cellulose ester is recovered, and the solvent removed from the film by drying in the film forming step of the recovered film is reused.

When preparing the above-mentioned dope, a method of dissolving the resin or the cellulose ester can be carried out by a general method, and in combination with heating and pressurization, it can be heated to a boiling point or higher at normal pressure, and at a boiling point of a solvent at a normal pressure or higher. It is preferable to stir and dissolve at a temperature in a range in which the solvent is not boiled under pressure, because it prevents the occurrence of a gel or a block-shaped undissolved matter called mamaco. Further, it is preferred to use a method in which a resin or a cellulose ester is mixed with a weak solvent to wet or swell, and then a good solvent can be further added for dissolution.

The pressurization can be carried out by a method of pressurizing an inert gas such as nitrogen or a method of increasing the vapor pressure of the solvent by heating. Heating by the outside Preferably, for example, a sleeve type is preferred because it is easy to control the temperature.

The heating temperature at which the solvent is added is preferably from the viewpoint of solubility of the resin or the cellulose ester, and when the heating temperature is too high, the productivity is deteriorated due to an excessively large pressure. The preferred heating temperature is 45 to 120 ° C, preferably 60 to 110 ° C, and 70 ° C to 105 ° C is preferred. Also, the pressure can be adjusted to the extent that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method may be used to dissolve the resin or the cellulose ester in a solvent such as methyl acetate.

Then, the resin or the cellulose ester solution is filtered using a suitable filter material such as a filter paper, and as the filter material, in order to remove insoluble matter or the like, it is preferable that the absolute filtration accuracy is small, but the absolute filtration accuracy is too small, and the filter material is likely to be generated. The problem of clogging, therefore, the filter material with an absolute filtration accuracy of 0.008 mm or less is preferable, the filter material of 0.001 to 0.008 mm is preferable, and the filter material of 0.003 to 0.006 mm is more preferable.

The material of the filter material is not particularly limited, and a general filter medium can be used. A filter material made of plastic such as polypropylene or Teflon (registered trademark) or a metal filter material such as stainless steel is preferable because no fiber is detached, and is removed by filtration. It is preferable to reduce the impurities contained in the resin or cellulose ester of the raw material, particularly to highlight foreign matter.

The meaning of the foreign matter is that the two polarizing plates are arranged in a crossed (Cross Nicols) state, and the rolled cellulose ester is disposed therebetween, and the light is irradiated from one side of the polarizing plate to the other side. when viewed polarizing plate, leakage of light from the opposite side of the light spot becomes visible, the number of bright spots over the 0.01mm diameter is 200 pieces / cm ² or less preferred, more preferably 100 / cm ² or less, and still more It is preferably 50 pieces/cm ² or less, and most preferably 0 to 10 pieces/cm ² or less. Further, a small number of bright spots of 0.01 mm or more are preferable.

The filtration of the dope can be carried out by a general method, while filtering at a temperature above the boiling point of the solvent at normal pressure and under a temperature range in which the solvent does not boil under pressure, and the filtration pressure difference before and after the filtration (referred to as The rise of the differential pressure is preferably less, preferably 45 to 120 ° C, preferably 45 to 70 ° C, and more preferably 45 to 55 ° C.

The filtration pressure is preferably small, and the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and even more preferably 1.0 MPa or less.

The casting of the dope is described here.

The metal support in the casting (casting) step is preferably a mirror-finishable surface, and as the metal support, a drum having a stainless steel conveyor belt or a cast and having a surface plated is preferably used. The casting width can be 1~4m, the surface temperature of the metal support in the casting step is set to -50 °C~ the boiling temperature of the solvent is not reached, and the higher temperature is better because the drying speed of the mesh can be accelerated. When the temperature is too high, the mesh may be foamed or the planarity may be deteriorated. A preferred support temperature of 0 to 40 ° C is suitable, and 5 to 30 ° C is more preferable.

Alternatively, it is preferable to peel the metal support in a state where a large amount of residual solvent is contained by gelation of the mesh by cooling.

The method of controlling the temperature of the metal support is not particularly limited, but a method of blowing warm air or cold air or a method of bringing warm water into contact with the inner side of the metal support may be used. Since the use of warm water allows for efficient heat transfer, the temperature of the metal support reaches a certain period of time and is preferred. Use temperature In the case of wind, there is a case where wind is used at a temperature higher than the target temperature.

In order to exhibit excellent planarity of the retardation film, the amount of residual solvent when the mesh is peeled off from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Preferably, it is 20 to 30% by mass or 70 to 120% by mass.

In the drying step of the roll-shaped retardation film, the mesh is peeled off from the metal support and further dried, and the amount of the residual solvent is preferably 1% by mass or less, more preferably 0.1% by mass or less. It is 0 to 0.01% by mass or less.

In the film drying step, drying is generally carried out by a drum drying method (a method in which a plurality of rollers disposed on the upper and lower sides are alternately dried by a web) or a web is conveyed by a tenter.

In the phase difference film according to the present invention, the amount of residual solvent of the mesh material which has been peeled off from the metal support is extended in the conveyance direction (=long dimension), and the net is held by a clip or the like. The tenter method at both ends of the object is preferably extended in the width direction.

The extending operation can be divided into a multi-stage implementation, and the one-axis extension can be performed in the conveying direction or the wide-side direction, or the two-axis extension can be performed in the conveying direction and the wide-side direction, and when extending, the extension can be performed simultaneously, or in stages Implementation. In this case, the meaning of the step is, for example, the extension of the extension direction may be sequentially performed, or the extension in the same direction may be performed in multiple stages, and the extension of the different directions may be added to any of the stages.

The preferred stretching ratio is 1.05 to 2 times, preferably 1.1 to 1.5 times. When extending, it can also be contracted in the conveying direction or the wide side direction, and it can be made into a contraction. It is also possible to carry out from 0.8 to 0.99, preferably from 0.9 to 0.99. Preferably, the area is 1.12 times to 1.44 times, preferably 1.15 times to 1.32 times, by extension of the conveying direction and extension or contraction in the width direction, which is preferably a stretching ratio of the conveying direction × a widthwise direction. The extension ratio is calculated.

Further, the term "extension direction" in the present invention is generally used in the case where the direction of the extension stress is directly applied during the stretching operation, and the final stretching ratio is also obtained when the two-axis is extended in multiple stages. The situation in which the larger one (that is, the direction that is usually the axis of the late phase) is used is used.

The elongation is extended by 1.1 to 1.5 times in the conveyance direction or the broad side direction, particularly in the range of ±10 ° C of the glass transition point of the resin or the cellulose ester, or by a film formed by casting a solution, When the residual solvent amount remains in the range of 2 to 100% by mass, it is 1.1 to 1.7 times in the conveyance direction or the widthwise direction, and can be controlled within the range of the desired hysteresis value.

(2nd phase difference layer)

The substrate used in the second retardation layer of the present invention is preferably easy to manufacture, optically transparent, and the like, and is preferably a transparent resin film.

The term "transparent" as used in the present invention means that the transmittance of visible light is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

It is not particularly limited as long as it has the above properties, and examples thereof include cellulose diacetate, cellulose triacetate, and cellulose acetate. a cellulose ester resin such as ester propionate or cellulose acetate butyrate, a polyester resin, a polycarbonate resin, a polyarylate resin, a polyfluorene (also containing a polyether oxime) resin, Polyethylene terephthalate, polyethylene naphthalate (polyethylene naphthalate), polyester resin, polyethylene resin, polypropylene resin, cellophane, polyvinylidene chloride resin, polyvinyl alcohol resin, Ethylene vinyl alcohol resin, syndiotactic polystyrene resin, norbornene resin, polymethylpentene resin, polyether ketone resin, polyether ketoximine resin, polyamine resin, fluororesin, polymethyl A methacrylate resin, an acrylic resin or the like is preferably used in which a norbornene-based resin and a cellulose ester-based resin are used.

The norbornene-based resin to be preferably used in the present invention is an amorphous polyolefin having a norbornene structure, for example, APO manufactured by Mitsui Petrochemical Co., Ltd. or ZEONEX, JSR (manufactured by Japan ZEON Co., Ltd.). ) ARTON and so on.

A preferred cellulose ester-based resin as the second retardation layer of the present invention, as cellulose ester, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose Acetate phthalate is preferred, and among them, cellulose acetate and cellulose acetate propionate are preferably used, and these resins are formed by melt casting or solution casting. The film is preferably thinned.

<Cellulose ester>

The cellulose ester which is suitable for use in the second retardation layer of the present invention will be described in detail.

The cellulose ester used in the second retardation layer of the present invention is preferably an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester or an aliphatic carboxylic acid ester and an aromatic carboxylic acid ester having a carbon number of 2 to 22 A mixed ester, particularly preferably a lower fatty acid ester of cellulose. The lower fatty acid ester of cellulose means lower fatty acid, and refers to a fatty acid having 6 or less carbon atoms, specifically, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate A cellulose acetate propionate or a cellulose acetate butyl group as described in JP-A No. 10-45804, JP-A No. 8-231761, and No. 2,319,052 A mixed fatty acid ester such as an acid ester or the like, and a lower fatty acid ester of cellulose which is particularly preferably used in the above description is a cellulose acetate propionate.

The cellulose ester having a fluorenyl group having 2 to 22 carbon atoms as a substituent, a degree of substitution of an ethyl fluorenyl group being X, and a degree of substitution of a fluorenyl group being Y, and a cellulose ester satisfying the following formulas 1 and 2 .

Equation 1 2.00≦X+Y≦2.60 Equation 2 0.10≦Y≦1.00

Among them, 2.30≦X+Y≦2.55 is preferred, 2.40≦X+Y≦2.55 is preferred, and 0.50≦Y≦0.90 is preferred, and 0.70≦Y≦0.90 is preferred.

The moiety which is not substituted by a mercapto group is usually present as a hydroxyl group, and these are synthesized by a conventional method. Further, the degree of substitution of the mercapto group can be measured in accordance with the method specified in ASTM-D817-96.

Cellulose esters can be synthesized alone or in combination with cotton linter, wood pulp, kenaf, etc. Separately or in combination, it is particularly preferred to use a cellulose ester synthesized from wood pulp alone or in combination with cotton wool (hereinafter, also referred to as cotton linter).

Further, the cellulose esters obtained by the above are each used in an arbitrary ratio, and the cellulose esters can be used as the cellulose raw material when the deuteration agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride). An organic solvent such as acetic acid or an organic solvent such as dichloromethane is used, which is obtained by a conventional reaction using a protonic catalyst such as sulfuric acid.

In the case of acetaminophen, if the rate of deuteration is to be increased, the time for the deuteration reaction must be prolonged. However, if the reaction time is too long, the decomposition proceeds simultaneously, causing the polymer chain to be cleaved or the decomposition of the acetyl group. Poor results. Therefore, in order to increase the degree of deuteration, and to some extent inhibit decomposition, the reaction time must be set within a certain range, and the reaction time requires various conditions, and other conditions such as a reaction device or equipment are not suitable for changing too much. Since the molecular weight distribution becomes wider as the decomposition of the polymer progresses, the decomposition of the cellulose ester is also defined by the value of the weight average molecular weight (Mw) / number average molecular weight (Mn) generally used. That is, the process of deuteration of cellulose triacetate can be used as a weight average molecular weight used as one of the indexes of the reaction which does not proceed too long and decomposes excessively, and the deuteration proceeds for a sufficient time to carry out the deuteration reaction. (Mw) / number average molecular weight (Mn) value.

The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the cellulose ester used in the present invention, Mw/Mn, is preferably from 1.4 to 3.0. Furthermore, in the present invention, the cellulose ester film is contained as a material. The cellulose ester having a Mw/Mn value of 1.4 to 3.0 may be used, but the overall Mw/Mn of the cellulose ester (preferably cellulose triacetate or cellulose acetate propionate) contained in the film may be used. A range of 1.4 to 3.0 is preferred. It is difficult to make the cellulose ester less than 1.4 in the synthesis process of cellulose ester, and the cellulose ester having a sufficient molecular weight can be obtained by gel filtration or the like, but the cost of the method is remarkably high, and, in addition, 3.0 or less The planarity is easy to maintain and is better, and more preferably, it is 1.7 to 2.2.

The molecular weight of the cellulose ester used in the present invention is preferably from 80000 to 200,000 in terms of number average molecular weight (Mn), more preferably from 100,000 to 200,000, and particularly preferably from 150,000 to 200,000.

The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high-speed liquid chromatography, and the number average molecular weight, the weight average molecular weight, and the ratio (Mw/Mn) thereof can be calculated.

The measurement conditions are as follows.

Solvent: Dichloromethane column: Shodex K806, K805, K803G (connected to Showa Denko (share) 3) Pipe column temperature: 25 °C Sample concentration: 0.1% by mass Detector: RI Model 504 (made by GLScience)浦:L6000 (Hitachi, Ltd.) Flow: 1.0ml/min calibration curve: 13 samples from standard polystyrene STK standard polystyrene (made by Tosoh Co., Ltd.) Mw=1000000~500 With the calibration curve obtained, 13 samples are preferably equally spaced.

The method for producing a cellulose ester can be obtained by the method described in JP-A-10-45804.

In addition, the cellulose ester is also affected by the trace amount of metal components in the cellulose ester, and it is considered that this is still related to the water produced in the production step, but it is preferable that the composition of the insoluble core is small, iron, Metal ions such as calcium and magnesium may form a salt with a polymer decomposition product or the like which may contain an organic acidic group, and may form an insoluble matter. The iron (Fe) component is preferably 1 ppm or less, and the calcium (Ca) component is contained in a large amount in the groundwater or the river water, and the content thereof is hard water, and is not suitable as a beverage water, but is easily mixed with a carboxylic acid or a sulfonate. An acidic component such as an acid or a complex compound is formed as a complex compound, that is, a complex compound, and a scum (insoluble precipitate or turbidity) derived from a large amount of insoluble calcium is formed.

The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. Regarding the magnesium (Mg) component, since it is too large, an insoluble component is produced, so it is preferably 0 to 70 ppm, particularly preferably 0 to 20 ppm. A metal component such as a content of iron (Fe), a content of calcium (Ca), and a content of magnesium (Mg) may be obtained by a micro-cooking wet decomposition apparatus (decomposition of sulfuric acid) by using an absolutely dried cellulose ester. After pretreatment with alkali fusion, it was analyzed by ICP-AES (Induction Combined Plasma Luminescence Spectroscopic Analysis Apparatus).

The refractive index of the cellulose ester film used in the present invention is preferably 550 nm 1.45 to 1.60, and the method for measuring the refractive index of the film is measured using an Abbe refractometer based on Japanese Industrial Standard JIS K 7105.

(additive)

The cellulose ester film may contain an additive such as a plasticizer or an ultraviolet absorber, an antioxidant, a matting agent or the like.

In the second retardation layer according to the present invention described above, the hysteresis value Ro in the plane is 0 ≦ Ro ≦ 50 nm, and the hysteresis value Rth in the thickness direction is 50 ≦ Rth ≦ 300 nm.

In order to make it into the above-mentioned numerical range, if a 2nd retardation layer is a cellulose ester film, it is manufactured by melt-film formation, and it is set as a solution, and it is preferable to hold it at the temperature of glass-

In particular, it can be achieved by making the in-plane retardation axis and the conveyance direction orthogonal to each other and controlling the unevenness in the plane. Therefore, the balance between the extension temperature and the extension ratio is precisely controlled to make the extension portion (the tenter of the tenter) The clips and the like are independently controlled independently on both sides of the phase difference layer, which can be achieved by adjusting the stretching temperature and the stretching ratio in accordance with the stress of the clip position and the clip.

<Other additives>

The first, second, and third retardation layers of the present invention may contain additives such as plasticizers, ultraviolet absorbers, and fine particles listed below.

The phase difference layer of the present invention preferably contains a plasticizer as described below, and as the plasticizer, for example, a phosphate ester plasticizer, a phthalate plasticizer, a trimellitate plasticizer, or the like can be preferably used. A benzenetetracarboxylic acid plasticizer, a glycolic acid ester plasticizer, a phthalate plasticizer, a polyester plasticizer, a polyol ester plasticizer, a sugar ester plasticizer, and the like.

Phosphate-based plasticizer, preferably triphenyl phosphate, tricresol Phosphate ester, cresol diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., phthalate-based plasticizer Use diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, two -2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, etc., in trimellitic acid plasticizer Tributyl trimellitate, triphenyl trimellitate, triethyl trimellitate, etc., tetrabutyl pyromellitate can be used in the pyromellitic plasticizer , tetraphenyl pyromellitic acid ester, tetraethyl pyromellitic acid ester, etc., glycolate ester plasticizer can use triacetin, glyceryl tributyrate, ethyl phthalate Ethyl glycolate, methyl phthalic acid ethyl glycolate, butyl phthalyl butyl glycolate, etc., triethyl phthalate can be used in the phthalate plasticizer Tri-n-butyl phthalic acid , Acetyl triethyl citrate ester, acetyl tri-butyl citrate -N- ester, acetyl tri -n- (2- ethylhexyl) citrate esters and the like. Examples of other carboxylic acid esters include butyl oleate, methyl decyl ricinolate, dibutyl sebacate, and various trimellitic acid esters.

A polyester-based plasticizer may be a copolymer of a dibasic acid such as an aliphatic dibasic acid, an alicyclic dibasic acid or an aromatic dibasic acid, and a glycol, and is not particularly useful as an aliphatic dibasic acid. As a limitation, adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid, etc. can be used; as the glycol, ethylene glycol, diethylene glycol, and 1 can be used. , 3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, and the like. These dibasic acids and glycols may be used alone or in combination of two or more.

The polyol ester-based plasticizer is composed of an ester of a divalent or higher aliphatic polyol and a monocarboxylic acid. Examples of preferred polyhydric alcohols include, for example, the following, but the present invention is 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- Butylene glycol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanediol, 1,5-pentanediol, 1,6-hexanediol , hexanetriol, 2-n-butyl-2-ethyl-1,3-propanediol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, tetramethyl Glycol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferred. The monocarboxylic acid to be used as the polyol ester of the present invention is not particularly limited, and a conventional aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid or the like can be used. The use of an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred from the viewpoint of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto. As the aliphatic monocarboxylic acid, a fatty acid having a linear or side chain having 1 to 32 carbon atoms is preferably used. The carbon number is preferably from 1 to 20, and from 1 to 10 is particularly preferred. When acetic acid is contained, it is preferable because it can increase compatibility with a cellulose derivative, and it is also preferable to use acetic acid and other monocarboxylic acids. Preferred aliphatic monocarboxylic acids may be acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecanoic acid, ten Dialkyl acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, behenic acid, Tetra-tetradecanoic acid, dihexadecanoic acid, heptacosic acid, octadecanoic acid, triacontane Saturated fatty acids such as acid and tridecanoic acid, unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and peanut pickling. Preferred examples of the alicyclic monocarboxylic acid may be cyclopentacarboxylic acid, cyclohexanecarboxylic acid, cyclooctylcarboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids, biphenylcarboxylic acids, naphthalenecarboxylic acids, and naphthalenes in which an alkyl group is introduced into a benzene ring of benzoic acid such as benzoic acid or xylonic acid. An aromatic monocarboxylic acid having two or more benzene rings, such as a carboxylic acid, or the like, and particularly preferably a benzoic acid. The molecular weight of the polyol ester is not particularly limited, and is preferably 300 to 1,500, more preferably 350 to 750, and more preferably from the viewpoint of retention, and moisture permeability and compatibility with cellulose. In terms of opinion, the smaller one is better.

The carboxylic acid to be used in the polyol ester to be used in the invention may be one type or a mixture of two or more types. Further, the OH group in the polyol may be esterified, or a part may remain in the OH group state.

As the sugar ester-based plasticizer, an esterified compound obtained by esterifying all or one of the OH groups in the compound (A) having one furanose structure or pyranose structure, or two or more bonds may be used. And a sugar ester compound in which all or a part of the OH group in at least one compound (B) of at least one of the furanose structure or the pyranose structure is esterified, and for example, the esterified compound is a monosaccharide (α) - benzoic acid ester of - glucose, β-fructose, or any two or more of -OR ₁₂ , -OR ₁₅ , -OR ₂₂ , -OR ₂₅ of the monosaccharide represented by the following general formula (A) is dehydration condensation The resulting benzoate of the polysaccharide of m+n=2-12 is exemplified. The benzoic acid may further have a substituent, and examples thereof include an alkyl group, an alkenyl group, an alkoxy group, and a phenyl group, and the alkyl group, the alkenyl group, and the phenyl group may have a substituent.

Examples of the preferable compound (A) and the compound (B) include the following, but the present invention is not limited thereto.

Examples of the compound (A) include glucose, galactose, mannose, fructose, xylose, and arabinose.

Examples of the compound (B) include lactose, sucrose, cane tetrasaccharide, 1F-fructose-based canetetraose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, Fibrose, maltotriose, raffinose or canetriose, in addition to gentiobiose, gentian trisaccharide, gentiotetraose, xylotriose or galactosyl sucrose. Among these compounds (A) and (B), a compound having both a furanose structure and a pyranose structure is particularly preferable, and for example, preferred are ruthenium or ruthenium. Sugar, hazelnut tetrasaccharide, 1F-fructose-based sugar cane tetrasaccharide, stachyose, more preferably sugar. Further, in the compound (B), one or more compounds having two or more and three or less furanose structures or a pyranose structure are one of preferable embodiments.

The monocarboxylic acid to be used in the compound (A) and the compound (B) of the present invention in which all or a part of the OH group is esterified is not particularly limited, and a conventional aliphatic monocarboxylic acid may be used. The alicyclic monocarboxylic acid, the aromatic monocarboxylic acid, and the like may be used alone or in combination of two or more.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanecarboxylic acid, Undecanoic acid, dodecanoic acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, nonadecanic acid, eicosanoic acid, a saturated fatty acid such as dodecanoic acid, tetracosanoic acid, hexadecanoic acid, heptacosanoic acid, octacosanoic acid, tridecanoic acid, or tridecanoic acid, undecylenic acid And unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and octenoic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, or the like.

Examples of preferred aromatic monocarboxylic acids include an alkyl group in which a benzene ring such as benzoic acid or toluic acid is introduced into an alkyl group, an alkoxy group, an aromatic monocarboxylic acid, a cinnamic acid, a diphenyl glycolic acid, and a combination. An aromatic monocarboxylic acid having two or more benzene rings, such as a benzenecarboxylic acid, a naphthalenecarboxylic acid or a naphthyl carboxylic acid, or a derivative thereof, more specifically, dimethylbenzoic acid, 2, 3 -Dimethylphenyl acid, 3,5-Dimethylbenzoic acid, tricresoleic acid, γ-heodoic acid, ruthenic acid, ketonic acid, α-isoduccinic acid, cumene acid, α-toluic acid, hydrogenated atropic acid , atropic acid, hydrogenated cinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, phenolic acid, o-high salicylic acid, m-high salicylic acid, p-high water Salicylic acid, o-pyroic acid, β-resorcinol, vanillic acid, isovaleric acid, cucurbitacic acid, o-cucurbit acid, gallic acid, asaric acid, mandelic acid, high anisic acid, High vanillic acid, sucralic acid, o-sorghumic acid, decanoic acid, p-calic acid.

Among the above-mentioned compound (A) and the compound (B) esterified sugar ester compound, it is preferred to introduce an acetamidine compound by esterification.

The details of the method for producing the acetyl group-based compound are described in JP-A-8-245678.

In addition to the esterified compound of the above compound (A) and the compound (B), the esterified compound of the oligosaccharide is also suitable as at least one of the 3 to 12 furanose structures or the pyranose structure of the present invention. Compound.

The oligosaccharide is produced by using an enzyme such as starch or sucrose with an enzyme such as an amylase, and is applicable to the oligosaccharide of the present invention, and examples thereof include malto-oligosaccharide, isomaltoligosaccharide, fructooligosaccharide, and milk oligosaccharide. Wood oligosaccharides.

The oligosaccharide can also be acetylated by the same procedure as the above compound (A) and the compound (B).

These plasticizers are preferably used singly or in combination.

The amount of the plasticizer to be used is preferably from 1 to 20% by mass, particularly preferably from 3 to 13% by mass, based on the film properties, workability and the like.

The ultraviolet absorber which can be used in the present invention has an object of improving the durability by absorbing ultraviolet rays of 400 nm or less, and particularly preferably having a transmittance of 10% or less at a wavelength of 370 nm, more preferably 5% or less, and still more preferably 2% or less.

The ultraviolet absorber used in the present invention is not particularly limited, and examples thereof include an oxybenzophenone-based compound, a benzotriazole-based compound, a salicylate-based compound, a benzophenone-based compound, and cyanoacrylic acid. An ester type compound, a triazine type compound, a nickel stear salt type compound, an inorganic powder, etc. may be a polymer type ultraviolet absorber.

The fine phase layer used in the present invention is preferably a fine particle, and a fine particle inorganic compound or an organic compound can be used. Examples of the inorganic compound include cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined clay, calcined calcium citrate, calcium citrate hydrate, aluminum citrate, magnesium citrate and The calcium phosphate and the fine particle system are preferred because they have a low turbidity, and particularly preferably cerium oxide.

The average particle diameter of the primary particles of the fine particles is preferably 5 to 50 nm, more preferably 7 to 20 nm, and the secondary aggregates having a particle diameter of 0.05 to 0.3 μm are preferably contained in the cellulose ester film. The content of the fine particles is preferably from 0.05 to 1% by mass, particularly preferably from 0.1 to 0.5% by mass. When the cellulose ester film composed of a plurality of layers of the co-casting method is used, it is preferred that the surface contains the added amount of fine particles.

The fine particles of cerium oxide can be sold, for example, under the trade names of AEROSILR972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Japan AEROSIL Co., Ltd.). By.

As the fine particles of zirconia, for example, those sold under the trade names of AEROSILR976 and R811 (manufactured by AEROSIL Co., Ltd., Japan) can be used.

Examples of the polymer include a polyoxyalkylene resin, a fluororesin, and an acrylic resin, preferably a polyoxyalkylene resin, and particularly preferably a three-dimensional network structure, and for example, Tospear 103, Tospear 105, Trade names of Tospear 108, Tospear 120, Tospear 145, Tospear 3120, and Tospear 240 (above, Toshiba Polyoxane Co., Ltd.) are sold.

Among these, AEROSIL 200V and AEROSIL R972V are particularly preferable because they maintain a low turbidity of the cellulose ester film and have a large effect of lowering the friction coefficient.

When the first retardation layer and the second retardation layer are bonded together, a conventional adhesive can be used, but an acrylic adhesive is preferred, and a method of laminating the first retardation and the second retardation layer is used. The method of directly coating the second retardation layer is applied in addition to the method of separately forming the film as described above. Immobilized. The method of extending the first retardation layer is also preferable. In this case, the axial misalignment does not occur at the time of film bonding which causes a decrease in contrast, and the advantage of being thinned is that the adhesive layer is not required.

(3rd phase difference layer)

In the third retardation layer according to the present invention, the retardation value in the in-plane and thickness directions is a retardation film in a range of 0 ≦ Ro ≦ 5 nm and 0 ≦ | Rth | < 40 nm, but is used as an IPS mode liquid crystal display device. Phase difference film used Preferably, it is particularly preferably in the range of 0 ≦ | Rth | < 10 nm.

The third retardation layer is a cellulose ester which is excellent in workability such as alkalization suitability as a protective film for a polarizing plate, and has a weight average molecular weight of 500 or more which exhibits negative alignment birefringence with respect to the extending direction. A cellulose ester film of an acrylic polymer of 30,000 or less is preferred. As the cellulose ester film, the same material and the same production method as those of the cellulose ester film used in the second retardation layer can be preferably used.

Further, the acrylic polymer is preferably an acrylic polymer having an aromatic ring in a side chain or an acrylic polymer having a cyclohexyl group in a side chain.

<acrylic polymer>

By making the weight average molecular weight of the acrylic polymer 500 or more and 30,000 or less and controlling the composition of the polymer, the compatibility of the cellulose ester with the polymer can be excellent.

In particular, the acrylic polymer, an acrylic polymer having an aromatic ring in a side chain, or an acrylic polymer having a cyclohexyl group in a side chain, if the weight average molecular weight is preferably 500 or more and 10,000 or less, in addition to the above, The cellulose ester film after film formation is excellent in transparency and extremely low moisture permeability, and is excellent in performance as a protective film for a polarizing plate.

Since the polymer has a weight average molecular weight of 500 or more and 30,000 or less, and is considered to be located between the oligomer and the low molecular weight polymer, it is difficult to control the molecular weight by synthesizing such a polymer, and it is desirable to use it without using it. A method in which the molecular weight is too large to make the molecular weight as complete as possible.

As the related polymerization method, for example, a dry peroxide is used. Or a method of peracidifying a polymerization initiator of t-butyl hydroperoxide, a method of using a polymerization initiator larger than a general polymerization in a large amount, or using a mercapto compound or carbon tetrachloride in addition to a polymerization initiator A method of using a chain transfer agent, a method of using a polymerization stopper such as phenylhydrazine or dinitrobenzene, in addition to a polymerization initiator, and using one of the publications of JP-A-2000-128911 or JP-A-2000-344823 A method of performing a bulk polymerization of a thiol and a hydroxyl group of a second stage, or a method of using a polymerization catalyst of the compound and an organometallic compound, and any of the methods is applicable to the present invention, but it is particularly preferably described in the publication. The method.

The monomer constituting the monomer unit of the polymer to be used in the present invention is as follows, but is not limited thereto.

The ethylenically unsaturated monomer unit constituting the polymer obtained by polymerizing the ethylenically unsaturated monomer: examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, and the like. Vinyl vinyl acetate, vinyl hexanoate, vinyl decanoate, vinyl dodecanoate, vinyl myristate, vinyl pentadecanoate, vinyl stearate, vinyl cyclohexylcarboxylate, Vinyl octoate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate, etc.; as the acrylate, for example, methyl acrylate, ethyl acrylate, propyl acrylate (for example) I-, n-), butyl acrylate (n-, i-, s-, t-), amyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), acrylic acid Heptyl ester (n-, i-), octyl acrylate (n-, i-), decyl acrylate (n-, i-), tetradecyl acrylate (n-, i-), cyclohexyl acrylate, Acrylic (2-ethylhexyl), benzyl acrylate, phenylethyl acrylate, propylene Acid (ε-caprolactone), acrylic acid (2-hydroxyethyl ester), acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester), acrylic acid (4-hydroxybutyl ester), acrylic acid (2-hydroxyl) Butyl ester), acrylic acid-p-hydroxymethylphenyl ester, acrylic acid-p-(2-hydroxyethyl)phenyl ester, etc.; as methacrylate, the above acrylate is changed to methacrylate; Examples of the saturated acid include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid and the like. The polymer composed of the above monomers may be a copolymer or a homopolymer, and a homopolymer of vinyl ester, a copolymer of vinyl ester, a copolymer of vinyl ester and acrylic acid or a methacrylate. good.

In the present invention, the term "acrylic polymer" (only referred to as acrylic polymer) means a homopolymer or a copolymer of acrylic acid or alkyl methacrylate which does not have a monomer unit containing an aromatic ring or a cyclohexyl group; The term "acrylic polymer having an aromatic ring in a side chain" means an acrylic polymer containing an acrylic or methacrylic acid monomer unit having an aromatic ring.

Further, the term "acrylic polymer having a cyclohexyl group in a side chain" means an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group.

Examples of the acrylate monomer having no aromatic ring and cyclohexyl group include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i-, s-, t). -), amyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), Ethyl acrylate (n-, i-), tetradecyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-hexine) Ester), acrylic acid (2-hydroxyethyl ester), acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester), acrylic acid (4-hydroxybutyl ester), acrylic acid (2-hydroxybutyl ester), acrylic acid ( 2-methoxyethyl ester), acrylic acid (2-ethoxyethyl ester), or the like, or the above acrylate is changed to methacrylate.

The acrylic polymer is preferably a homopolymer or a copolymer of the above monomer, and preferably contains 30% by mass or more of a methyl acrylate monomer unit, and more preferably 40% by mass or more of a methyl methacrylate monomer unit. A homopolymer of methyl acrylate or methyl methacrylate is particularly preferred.

Examples of the acrylic or methacrylic ester monomer having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl ester), and methacrylic acid (2 or 4-chlorophenyl ester). , acrylic acid (2 or 3 or 4-ethoxycarbonylphenyl ester), methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl ester), acrylic acid (o or m or p-toluate), methacrylic acid (o or m or p-toluate), benzyl acrylate, benzyl methacrylate, phenylethyl acrylate, phenylethyl methacrylate, 2-(naphthyl) acrylate, etc., but benzyl acrylate is preferably used. Ester, benzyl methacrylate, phenylethyl acrylate, phenylethyl methacrylate.

Among the acrylic polymers having an aromatic ring on the side chain, the acrylic or methacrylic acid monomer unit having an aromatic ring has 20 to 40% by mass, and the acrylic or methyl methacrylate monomer unit has 50 to 80% by mass. Preferably, in the polymer, the acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group is preferably 2 to 20% by mass.

As the acrylate monomer having a cyclohexyl group, for example, acrylic acid is exemplified. Cyclohexyl ester, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl ester), methacrylic acid (4-methylcyclohexyl ester), acrylic acid (4-ethylcyclohexyl ester), methacrylic acid ( As the 4-ethylcyclohexyl ester or the like, cyclohexyl acrylate and cyclohexyl methacrylate are preferably used.

The acrylic polymer having a cyclohexyl group in the side chain has 20 to 40% by mass of an acrylic or methacrylic acid monomer unit having a cyclohexyl group and preferably has 50 to 80% by mass, and further, in the polymer Preferably, the acrylic or methacrylic acid monomer unit having 2 to 20% by mass of a hydroxyl group is preferred.

a polymer obtained by polymerizing the above ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in a side chain, and an acrylic polymer having a cyclohexyl group on a side chain thereof, and a phase of a cellulose resin Excellent solubility.

When such a hydroxyl group-containing acrylic acid or methacrylic acid ester monomer is not a homopolymer, it is a constituent unit of a copolymer, and in this case, an acrylic or methacrylic monomer unit having a hydroxyl group is preferred. It is preferably 2 to 20% by mass in the acrylic polymer.

In the present invention, a polymer having a hydroxyl group in a side chain may also be used. The monomer unit having a hydroxyl group is the same as the above-mentioned monomer, but acrylic acid or methacrylic acid ester is preferable, and acrylic acid (2-hydroxyethyl) is exemplified. Ester), acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester), acrylic acid (4-hydroxybutyl ester), acrylic acid (2-hydroxybutyl ester), acrylic acid-p-hydroxymethylphenyl ester, acrylic acid -p-(2-hydroxyethyl)phenyl ester, or such acrylic acid is replaced by methacrylic acid, preferably 2-hydroxyethyl acrylate and methyl propyl acrylate 2-hydroxyethyl enoate. The acrylate or methacrylate monomer unit having a hydroxyl group in the polymer is preferably 2 to 20% by mass, more preferably 2 to 10% by mass in the polymer.

The polymer having 2 to 20% by mass of the above-mentioned monomer unit having a hydroxyl group is excellent in compatibility, retention, and dimensional stability with a cellulose ester, and is not only a small moisture permeability but also a polarizing plate. The polarizer of the protective film is particularly excellent in adhesion, and has an effect of improving the durability of the polarizing plate.

The method of providing a hydroxyl group at the terminal of at least one of the main chains of the acrylic polymer is not particularly limited as long as it has a hydroxyl group at the terminal of the main chain, and can be used, for example, by using azobis(2-hydroxyethyl). A method of a radical polymerization initiator having a hydroxyl group, a method using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method using a polymerization stopper having a hydroxyl group, and a living ion polymerization It is a method of having a hydroxyl group at the terminal, and a compound having a thiol group and a hydroxyl group of 2, such as JP-A-2000-128911 or JP-A-2000-344823, or using the compound and an organometallic compound. The polymerization catalyst is obtained by a bulk polymerization method or the like, and is particularly preferably a method described in the publication.

The polymer obtained by the method described in the publication is suitable for use in the Actoflow series of products manufactured by Amika Chemical Co., Ltd. The polymer having a hydroxyl group at the terminal and/or a polymer having a hydroxyl group in the side chain is a polymer having a synergistic effect on the compatibility and transparency of the polymer.

And as a negative alignment birefringence with respect to the direction of extension The ethylenically unsaturated monomer is preferably a styrene-based polymer which exhibits a negative refractive index. Examples of the styrene include styrene, methyl styrene, dimethyl styrene, and the like. Methylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, ethoxylated styrene, chlorostyrene, dichlorostyrene, bromostyrene, vinylbenzene Methyl formate or the like, but is not limited thereto.

It may be copolymerized with an exemplary monomer exemplified as the unsaturated ethylenic monomer, and may be used by dissolving two or more kinds of the above polymer phases in a cellulose resin for the purpose of controlling birefringence.

Further, the third retardation layer of the present invention contains an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule, and an ethylenic unsaturated group having no hydrophilic ring in the molecule and having a hydrophilic group. It is preferable that the polymer X having a weight average molecular weight of 5,000 or more and 30,000 or less obtained by copolymerization of the monomer Xb and the polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerization of the ethylenically unsaturated monomer Ya having no aromatic ring are preferably obtained. .

(Polymer X, Polymer Y)

The polymer X used in the present invention is obtained by copolymerizing an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule with an ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group. The polymer X having a weight average molecular weight of 5,000 or more and 30,000 or less obtained later is preferably a propylene group or a methacryl monomer which does not have an aromatic ring and a hydrophilic group in the molecule, and Xb contains no aromatic ring in the molecule. Hydrophilic A propylene or methacryl monomer based.

The polymer X used in the present invention is represented by the following general formula (X).

General formula (X)-(Xa)m-(Xb)n-(Xc)p-

The polymer represented by the following general formula (X-1) is preferred.

General formula (X-1)-[CH ₂ -C(-R1)(-CO ₂ R2)]m-[CH ₂ -C(-R3)(-CO ₂ R4-OH)-]n-[Xc] P- (wherein R1 and R3 represent H or CH ₃ . R 2 represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R ₄ represents -CH ₂ -, -C ₂ H ₄ - or -C ₃ H ₆ - Xc represents a monomer unit in which Xa and Xb are polymerizable. m, n and p represent a molar composition ratio. However, m≠0, n≠0, k≠0, m+n+p=100.

The monomer constituting the monomer unit of the polymer X used in the present invention is as follows, but is not limited thereto.

In X, the hydrophilic group is a group having a hydroxyl group or an ethylene oxide chain.

Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and hydrophilic group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i). -, s-, t-), amyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n -, i-), decyl acrylate (n-, i-), Tetradecyl acrylate (n-, i-), acrylic acid (2-ethylhexyl ester), acrylic acid (ε-caprolactone), acrylic acid (2-ethoxyethyl ester), etc., or the above acrylate To methacrylate. Among them, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferred.

In the ethylenically unsaturated monomer Xb having a hydrophilic group, the monomer having a hydroxyl group is preferably acrylic acid or methacrylate, and examples thereof include acrylic acid (2-hydroxyethyl ester). Acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester), acrylic acid (4-hydroxybutyl ester), acrylic acid (2-hydroxybutyl ester), or such acrylic acid is replaced by methacrylic acid, preferably It is acrylic acid (2-hydroxyethyl ester) and methacrylic acid (2-hydroxyethyl ester), acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester).

Xc is not particularly limited as long as it is a copolymerizable ethylenically unsaturated monomer other than Xa or Xb, and is preferably an aromatic ring.

The molar composition ratio m:n of Xa, Xb and Xc is preferably in the range of 99:1 to 65:35, more preferably in the range of 95:5 to 75:25. The p of Xc represents 0~10, and Xc can be a plural monomer unit.

When the molar composition ratio of Xa is too large, the compatibility with the cellulose ester is improved, but the retention value Rth in the thickness direction of the film is excessively large. When the composition ratio of the Mob of Xb is too large, the compatibility is deteriorated, but the effect of reducing Rth is improved. Further, when the molar composition ratio of Xb exceeds the above range, a haze value tends to occur at the time of film formation, and it is preferable to optimize the Moor composition ratio of Xa and Xb in order to obtain the optimum.

The molecular weight of the polymer X is a weight average molecular weight of 5,000 or more and 30,000 or less, more preferably 8,000 or more and 25,000 or less.

When the weight average molecular weight is 5,000 or more, it is preferable to obtain a cellulose ester film having a small dimensional change under high temperature and high humidity, and having a small curl as a polarizing plate protective film. When the weight average molecular weight is 30,000 or less, the compatibility with the cellulose ester can be improved, the bleeding can be suppressed under high temperature and high humidity, and the haze value after the film formation can be suppressed.

The weight average molecular weight of the polymer X of the present invention can be adjusted by a known molecular weight adjustment method. As a method of adjusting the molecular weight, for example, a method of adding a chain shifting agent such as carbon tetrachloride, lauryl mercaptan or octyl thioglycolate may be mentioned. Further, the polymerization temperature is usually from room temperature to 130 ° C, preferably from 50 ° C to 100 ° C, but the temperature or the polymerization reaction time can be adjusted.

The method for measuring the weight average molecular weight can be carried out by the following method.

(Method for measuring weight average molecular weight)

The weight average molecular weight Mw can be measured using gel permeation chromatography.

The measurement conditions are as follows.

Solvent: Dichloromethane column: Shodex K806, K805, K803G (using a column connected with Showa Denko (stock) connected to 3) Column temperature: 25 ° C Sample concentration: 0.1% by mass Detector: RI Model 504 ( GL Science Corporation) Pump: L6000 (Hitachi, Ltd.) Flow: 1.0ml/min Calibration curve: 13 samples of standard polystyrene STK Standard polystyrene (made by Tosoh Co., Ltd.) Mw=1000000~500 Calibration curve, 13 samples used almost equal intervals.

The polymer Y used in the present invention is a polymer having a weight average molecular weight of 500 or more and 3,000 or less obtained by polymerization of the ethylenically unsaturated monomer Ya having no aromatic ring.

When the weight average molecular weight is 500 or more, the residual monomer of the polymer is preferably reduced, and when it is 3,000 or less, the retention value Rth is improved, which is preferable.

Ya is preferably a propylene or methacryl monomer having no aromatic ring.

The polymer Y of the present invention is represented by the following general formula (Y).

General formula (Y)-(Ya)k-(Yb)q-

The polymer represented by the following general formula (Y-1) is preferred.

General formula (Y-1)-[CH ₂ -C(-R5)(-CO ₂ R6)]k-[Yb]q- (wherein R5 represents H or CH ₃ and R6 represents a carbon number of 1 to 12 An alkyl group or a cycloalkyl group, Yb represents a monomer unit copolymerizable with Ya, and k and q represent a molar composition ratio. However, k≠0, k+q=100.

Yb is only an ethylenically unsaturated monomer copolymerizable with Ya, and is not particularly limited. Yb can be plural. k+q=100, q is preferably 0~30.

The ethylenically unsaturated monomer Ya which is a polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is an acrylate, and examples thereof include methyl acrylate, ethyl acrylate, and propyl acrylate (i-, n). -), butyl acrylate (n-, i-, s-, t-), amyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n -, i-), octyl acrylate (n-, i-), decyl acrylate (n-, i-), tetradecyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2-B) Hexyl hexyl ester), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl ester), acrylic acid (2-hydroxypropyl ester), acrylic acid (3-hydroxypropyl ester), acrylic acid (4-hydroxybutyl ester), Acrylic acid (2-hydroxybutyl ester) and methacrylate are those obtained by changing the above acrylate to methacrylate; examples of the unsaturated acid include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, and itaconic acid. Wait.

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya, and examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, and the like. Vinyl vinyl acetate, vinyl hexanoate, vinyl decanoate, vinyl dodecanoate, vinyl myristate, vinyl hexadecanate, vinyl stearate, vinyl cyclohexaneate, Vinyl octoate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate are preferred. Yb can also be plural.

When synthesizing the polymers X and Y, it is difficult to control the molecular weight in general polymerization, and it is preferred to use a method in which the molecular weight is not excessively controlled as much as possible. The related polymerization method may be a method in which a peroxide polymerization initiator such as cumene peroxide or a tert-butyl hydroperoxide is used, a method in which a polymerization initiator is used in a larger amount than a general polymerization, and a polymerization initiator are used. In addition to the method of using a chain transfer agent such as a hydrogenthio compound or carbon tetrachloride, and a polymerization initiator such as phenylhydrazine or dinitrobenzene, a polymerization initiator such as phenylhydrazine or dinitrobenzene may be used, and it is also possible to use, for example, JP-A-2000-128911. No. 2000-344823, a block polymerization method having a compound of a thiol and a secondary hydroxyl group, or a polymerization catalyst using the compound and an organometallic compound, can be used in the present invention, particularly A polymerization method in which a compound having a thiol group and a hydroxy group in the molecule is used as a chain shifting agent is preferred.

At this time, the terminal of the polymer X and the polymer Y have a hydroxyl group or a thioether caused by a polymerization catalyst and a chain shifting agent. The terminal residue can be used to adjust the compatibility of the polymers X, Y with the cellulose ester.

The hydroxyl group valence of the polymers X and Y is preferably from 30 to 150 [mgKOH/g].

(Method for measuring hydroxyl value)

This measurement was carried out in accordance with JIS K 0070 (1992), and the hydroxyl value is the number of mg of potassium hydroxide required for neutralization of acetic acid bonded to a hydroxyl group when 1 g of the test product is acetylated. Specifically, after the test sample Xg (about 1 g) was weighed in a flask, 20 ml of acetonitrile-based test music (in which 20 ml of acetic anhydride was added and pyridine was added thereto and 400 ml) was added thereto. Flask The air cooling tube is attached to the mouth and heated in a glycerin bath at 95~100 °C.

After cooling for 1 hour and 30 minutes, 1 ml of pure water was added from an air cooling tube to decompose acetic anhydride into acetic acid, and then a potentiometric titration device was used for titration of a 0.5 mol/L potassium hydroxide ethanol solution, and the obtained curve of the titration curve was used as a curve. end. And as a blank test, the titration of the titration curve is obtained by titrating without adding a sample.

The hydroxyl value is calculated by the following formula.

Hydroxy valence = {(B - C) × f × 28.05 / X} + D (wherein B represents the amount of 0.5 mol / L potassium hydroxide ethanol solution (ml) used in the blank test, and C represents 0.5 mol for titration /L potassium hydroxide ethanol solution amount (ml), f represents the factor of 0.5 mol / L potassium hydroxide ethanol solution, D represents the acid value, and 28.05 represents the amount of potassium hydroxide 1 mol of 56.11 1/2)

Both the polymer X and the polymer Y are excellent in compatibility with the cellulose ester, and are excellent in productivity without evaporation or volatilization, and are excellent in retention of the protective film for a polarizing plate, small in moisture permeability, and excellent in dimensional stability.

The content of the cellulose ester film of the polymer X and the polymer Y is preferably in the range of the following formulas (i) and (ii). The content of the polymer X is Xg (% by mass = mass of the polymer X / mass of the cellulose ester × 100), and the content of the polymer Y is Yg (% by mass), and the formula (i) is 5 ≦ Xg + Yg ≦ 35 ( quality%) The preferred range of the formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4 (i) is 10 to 25% by mass.

When the total amount of the polymer X and the polymer Y is 5% by mass or more, the amount of the retention value Rth is sufficiently reduced, and when the total amount is 35% by mass or less, the polarizer PVA is used. Excellent adhesion.

The polymer X and the polymer Y can be directly added, dissolved, or previously dissolved in an organic solvent in which a cellulose ester is dissolved, and added to the dope as a raw material constituting the dope.

<Other>

In addition to the cellulose ester or the acrylic polymer, a cyclic olefin resin, a polyester, a polycarbonate, or the like may be melt-formed, and may be made into 0≦Ro≦5 nm and 0 without stretching treatment. A phase difference film of ≦|Rth|<40 nm.

[Examples]

The present invention will be specifically described below by way of examples, but the present invention is not limited thereto.

(Measurement of hysteresis values Ro, Rth, Nz)

The hysteresis value of the retardation film was measured using an automatic complex refractometer KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), and measured at 23 ° C, In a 55% RH environment, three-dimensional refractive index measurement was performed at 10 measurements in a wavelength of 590 nm, and refractive indices nx, ny, and nz were calculated. The hysteresis value Ro in the in-plane direction is calculated according to the following equation, and the hysteresis values Rth and Nz in the thickness direction are calculated, and 10 points are measured, and the average value is shown.

Ro=(nx-ny)×d Rth={(nx+ny)/2-nz}×d Nz=(nx-nz)/(nx-ny) (wherein, Ro represents the in-plane hysteresis value of the film, and Rth represents the film. The hysteresis value in the thickness direction, nx represents the refractive index in the direction of the slow axis in the plane of the film, ny represents the refractive index in the direction of the phase in the film plane, nz represents the refractive index in the thickness direction of the film, and d represents the thickness of the film (nm) ).)

<Preparation of retardation film 1> (modulation of glue 1)

The above was put into a sealed container, and it was completely dissolved while being heated and stirred, and filtered by a filter paper No. 24 made of an ampoule filter paper. The cellulose ester mixture was filtered through a FINEMET NF manufactured by Nippon Seisaku Co., Ltd. in a film forming line.

(cerium oxide dispersion)

After stirring and mixing for 30 minutes with a dissolver, it was dispersed by Marton's eucalyptus (emulsion apparatus), and the liquid turbidity after dispersion was 200 ppm, and 80 parts by mass of dichloromethane was added while stirring in the cerium oxide dispersion. The dissolver was stirred and mixed for 30 minutes to prepare a cerium oxide dispersion diluent. Then, 10 parts by mass of a cerium oxide dispersion diluent was added to 100 parts by mass of the above cellulose ester mixture, and the mixture was sufficiently stirred to prepare a dope 1.

Using a strip casting device, the dope 1 was uniformly cast on a stainless steel belt support at a temperature of 35 ° C and a width of 1800 mm, and the solvent was evaporated until the amount of residual solvent became 100% in the stainless steel belt support. The body was peeled off, and the fiber of the peeled cellulose ester was evaporated at 55 ° C to make the slit width of 1650 mm wide, and then, while being stretched by 1.05 times with a tenter, the handling tension was applied in the MD direction (with the film). Handling The direction was paralleled by 1.05 times at 160 ° C. At this time, the amount of residual solvent when the tenter was stretched was 18%. Then, the drying zone of 140° C. and 110° C. was conveyed by a plurality of rollers to dry it, and slitting was performed at 1500 mm. An embossing process having a width of 15 mm and an average height of 10 μm was applied to both ends of the film to take up an initial tension of 220 N. /m, the final tension 110N/m is taken up in the inner diameter of 6 inch winding core to obtain the retardation film 1, the residual solvent amount of the retardation film 1 is 0.1%, the average film thickness is 40 μm, and the number of windings is 4000 m, this phase The poor film 1 had a Ro of 0 nm and an Rth of 50 nm.

<Production of retardation film 2>

The dope 1 was produced in the same manner as the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and then 160 ° C in the TD direction (the conveyance direction and the orthogonal direction of the film) by a tenter. In the same manner as the retardation film 1 except that the amount of the residual solvent at the time of the start of the stretching was 18%, the amount of the residual solvent was 18%, and the drying was performed while transporting the drying zone at 160 ° C and 110 ° C on a plurality of rolls. Phase difference film 2. The amount of residual solvent of the retardation film 2 was 0.1%, the average film thickness was 90 μm, the number of turns was 4000 m, Ro was 5 nm, Rth was 100 nm, and the direction of the slow axis was TD.

<Preparation of retardation film 3>

In the same manner as the retardation film 1, the dope 1 was produced in the same manner as in the case of the flow, the peeling, and the slitting on the tape, and the carrier was stretched by 1.05 times in the TD direction, and the carrier tension was applied thereto in the MD direction. °C extends 1.1 times, at this time, the amount of residual solvent at the start of stretching with a tenter In the same manner as the retardation film 1 except that the film was dried at 120 ° C and 110 ° C, the retardation film 3 was obtained. The amount of residual solvent of the retardation film 3 was 0.1%, the average film thickness was 80 μm, the number of turns was 4000 m, Ro was 5 nm, Rth was 100 nm, and the direction of the slow axis was MD.

<Preparation of retardation film 4>

In the same manner as the retardation film 1, the dope 1 was produced in the same manner as in the flow, the peeling, and the slitting on the tape, and the carrier tension was applied at 160 ° C in the MD direction by 1.15 times, and then the tenter was used in the TD direction. The retardation film 4 was obtained in the same manner as the retardation film 1 except that the stretching was 1.15 times. The amount of residual solvent at the start of stretching was 18%. The amount of residual solvent of the retardation film 4 was 0.1%, the average film thickness was 60 μm, the number of turns was 4000 m, Ro was 0 nm, and Rth was 200 nm.

<Preparation of retardation film 5>

The dope 1 was produced in the same manner as in the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and the transfer tension was applied at 160 ° C for 1.2 times in the MD direction, and then the tenter was applied in the TD direction. The retardation film 5 was obtained in the same manner as the retardation film 1 except that the retardation film 5 was stretched by 1.2 times. The amount of residual solvent at the start of stretching was 18%, the residual solvent amount of the retardation film 5 was 0.1%, and the average film thickness was 70 μm. It is 4000 m, Ro is 0 nm, and Rth is 300 nm.

<Preparation of retardation film 6>

The dope 1 was produced in the same manner as in the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and the carrier tension was extended by 1.2 times in the MD direction at 160 ° C, and then the tenter was used in the TD direction. The retardation film 6 was obtained in the same manner as the retardation film 1 except that the stretching was 1.15 times. The amount of residual solvent at the time of initial stretching was 18%, the residual solvent amount of the retardation film 6 was 0.1%, the average film thickness was 60 μm, the number of windings was 4000 m, Ro was 30 nm, Rth was 200 nm, and the direction of the slow axis was MD.

<Preparation of retardation film 7>

The dope 1 was produced in the same manner as the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and the carrier tension was extended by 121 times in the MD direction at 160 ° C, and then the tenter was used in the TD direction. The retardation film 6 was obtained in the same manner as the retardation film 1 except that the stretching was 1.15 times. The amount of residual solvent at the start of stretching was 18%, the residual solvent amount of the retardation film 6 was 0.1%, the average film thickness was 60 μm, the number of windings was 4000 m, Ro was 50 nm, Rth was 200 nm, and the direction of the slow axis was MD.

<Preparation of retardation film 8>

The dope 1 was produced in the same manner as in the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and the transfer tension was applied at 160 ° C in the MD direction by 1.17 times, and then the tenter was placed in the TD direction. The retardation film 8 was obtained in the same manner as the retardation film 1 except that the stretching was 1.17 times. The amount of residual solvent at the start of elongation was 18%, the amount of residual solvent of the retardation film 8 was 0.1%, the average film thickness was 60 μm, and the number of rolls was 4000 m, Ro. It is 0 nm and Rth is 150 nm.

<Production of retardation film 9>

In the same manner as in the retardation film 1, the dope 1 was produced in the same manner as in the flow, the peeling, and the slitting on the tape, and the conveyance tension was extended by 1.3 times in the MD direction at 160 ° C, and then heated at 190 ° C, and the phase was applied. The poor film 1 is similarly obtained to obtain a retardation film 9. The amount of residual solvent at the time of initial stretching was 18%, the residual solvent amount of the retardation film 9 was 0.1%, the average film thickness was 60 μm, the number of windings was 4000 m, Ro was 80 nm, Rth was 150 nm, and the direction of the slow axis was MD.

<Preparation of retardation film 10>

The dope 1 was produced in the same manner as in the retardation film 1, and was carried out in the same manner as in the flow, the peeling, and the slitting on the tape, and the transfer tension was applied at 160 ° C for 1.2 times in the MD direction, and then the tenter was applied in the TD direction. The retardation film 10 was obtained in the same manner as the retardation film 1 except that the film was stretched by 1.2 times. The amount of residual solvent at the start of stretching was 18%, the amount of residual solvent of the retardation film 10 was 0.1%, the average film thickness was 120 μm, the number of turns was 4000 m, Ro was 0 nm, and Rth was 350 nm.

<Preparation of retardation film 11> (Synthesis of Polymer X)

In the glass flask with a blender, two dropping funnels, a glass inlet tube, and a thermometer, the types and ratios shown in Table 1 were loaded. 40 g of a mixture of monomers Xa and Xb, 2 g of mercaptopropionic acid of a chain transfer agent, and 30 g of toluene, and the temperature was raised to 90 ° C, and then the types and ratios shown in Table 1 were compared from one dropping funnel. 60 g of the mixture of the monomers Xa and Xb was dropped over 3 hours, and 0.4 g of azobisisobutyronitrile dissolved in 14 g of toluene was dropped from one funnel over 3 hours, and then dissolved in 56 g of toluene. After 0.6 g of nitrogen diisobutyronitrile was dropped over 2 hours, the reaction was further continued for 2 hours to obtain a polymer X. The obtained X was a solid at normal temperature, and the weight average molecular weight of the polymer X is shown in Table 1 by the following measurement method.

In addition, each of MMA and HEA described in Table 1 is an abbreviation of the following compounds.

MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate

(weight average molecular weight determination)

The measurement of the weight average molecular weight was carried out using gel permeation chromatography.

The measurement conditions are as follows.

Solvent: Dichloromethane column: Shodex K806, K805, K803G (for connection with Showa Denko (share) 3) Column temperature: 25 °C Sample concentration: 0.1% by mass Detector: RI Model 504 (manufactured by GLS Science) Pump: L6000 (Hitachi Manufacturing Co., Ltd.) Flow: 1.0ml/min calibration curve: using standard polystyrene STK standard polystyrene (made by Tosoh Co., Ltd.) Mw=1000000~500 13 samples Calibration curve, 13 samples used almost equal intervals.

(Synthesis of Polymer Y)

The block polymerization is carried out by a polymerization method described in JP-A-2000-128911, that is, a flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, an inlet, and a circulation cooling tube, and the following The acrylate (MA) was introduced with nitrogen, and the inside of the flask was replaced with nitrogen. The following thioglycerol was added under stirring. After the thioglycerol was added, the temperature of the contents was appropriately changed and polymerization was carried out for 4 hours, and the contents were returned to room temperature. 20 parts by mass of a benzoquinone 5 mass% tetrahydrofuran solution was added thereto to stop the polymerization, and the contents were transferred to an evaporator, and tetrahydrofuran, residual monomers, and residual sulfur glycerin were removed under reduced pressure at 80 ° C to obtain the contents shown in Table 1. In the polymer Y, the obtained Y was a liquid at normal temperature, and the weight average molecular weight of the polymer Y is shown in Table 1 by the above measurement method.

<Composition of glue> (cerium oxide dispersion)

The mixture was stirred and mixed for 30 minutes with a dissolver, and then dispersed in a Marton Eucalyptus (emulsion apparatus) to have a liquid turbidity of 200 ppm after dispersion, and 88 parts by mass of dichloroethylene was added to the cerium oxide dispersion while stirring. Methane was stirred and mixed in a dissolver for 30 minutes to prepare a cerium oxide dispersion diluent.

(glue addition liquid)

In the above, the dichloromethane and the polymer X and the polymer Y are completely dissolved while stirring, and then the cerium oxide dispersion is added thereto, followed by stirring and mixing to prepare a dope addition liquid.

(modulation of the main glue)

The above-mentioned ones were placed in a sealed container, and the mixture was heated, stirred, and completely dissolved, and filtered using an Augmentation filter paper No. 24 made of a filter paper to prepare a main dope.

The main dope slurry was filtered by FINEMET NF manufactured by Nippon Seisaku Co., Ltd., and was uniformly cast on a stainless steel belt support at a temperature of 22 ° C and a width of 2 m using a strip casting apparatus to evaporate the solvent in a stainless steel belt support. When the amount of the residual solvent became 105%, the peeling tension was 162 N/m from the stainless steel belt support, and the peeled cellulose ester web was evaporated at 35 ° C to make the slit width 1.6 m wide, and then pulled. The web was stretched 1.1 times and dried at a drying temperature of 135 °C. At this time, the amount of residual solvent at the start of stretching by the tenter was 10%, and after stretching by a tenter, the width of the wide-side tension was maintained at 130 ° C, and the drying zone at 120 ° C and 130 ° C was used as a roller. After the drying, the drying was completed, and slitting was performed at a width of 1.5 m, and a pressure of 10 mm in height and 7 μm in height was applied to both ends of the film. The flower processing was wound around a 6-inch inner diameter core at an initial tension of 220 N/m and a final tension of 110 N/m to obtain a cellulose ester film 1. The stretching ratio in the MD direction calculated from the rotation speed of the stainless steel belt support and the running speed of the tenter is 1.1 times, and the residual solvent amount of the retardation film 11 is less than 0.1%, the film thickness is 40 μm, Ro5 nm, Rth-5nm.

<Preparation of retardation film 12> (cerium oxide dispersion A)

After mixing and mixing for 30 minutes with a dissolver, the mixture was dispersed in a Marton Eucalyptus (emulsion apparatus), and the liquid turbidity after dispersion was 200 ppm, and 88 parts by mass of dichloromethane was added while stirring in the ceria dispersion. The mixture was mixed with a dissolver for 30 minutes to prepare a cerium oxide dispersion diluent A.

(production of in-line addition liquid A)

The above-listed persons were placed in a closed container, heated, stirred, and completely dissolved and filtered.

36 parts by mass of cerium oxide dispersed while stirring After the dilution A was further stirred for 30 minutes, 6 parts by mass of cellulose acetate propionate (acetate substitution degree 1.9, propyl thiol substitution degree 0.8) was added while stirring, and after stirring for 60 minutes, ADVANTEC Toyo was used. (Fly) polypropylene wound cartridge filter TCW-PPS-1N filtration, in-line addition of liquid A.

(Modulation of glue A)

In the sealed container, the above-mentioned ones were placed, heated, stirred, and completely dissolved, and filtered using a filter paper No. 24 made of a filter paper (manufactured with a filter paper) to prepare a slurry A.

In the membrane line, FINEMET NF filter slurry A made by Nippon Seisakusho Co., Ltd. is added to the in-line addition liquid line, and the liquid A is added to the FINEMET NF filter tube made by Nippon Seiki Co., Ltd., relative to the filtered 100 parts by mass of the cement A, the filtered in-line addition liquid A is added in a ratio of 3 parts by mass, and thoroughly mixed with an in-line mixer (Tosoh static in-line mixer Hi-Mixer, SWJ), and then, The strip casting device is uniformly cast on the stainless steel belt support at a temperature of 32 ° C and 1800 mm width. The stainless steel belt support, evaporating the solvent until the residual solvent amount becomes 100%, peeling off from the stainless steel belt support, ejecting the cellulose ester web at 35 ° C, slitting at a width of 1650 mm, and then using a tenter The machine was stretched 1.05 times in the TD direction (the direction in which the film was conveyed in the vertical direction), and dried at a drying temperature of 135 ° C. At this time, the amount of residual solvent when stretching was started by a tenter was 20%.

Then, the drying zone at 120 ° C and 110 ° C was dried while being conveyed by a plurality of rollers, and slit at a width of 1400 mm, and embossing was performed at both ends of the film with a width of 15 cm and an average height of 10 μm to obtain an initial tension at the winding. 220 N/m and an end tension of 110 N/m are wound by a 6-inch inner diameter core to obtain a retardation film 12, and the MD immediately after peeling is calculated from the rotation speed of the stainless steel belt support and the running speed of the tenter. The stretching ratio in the direction (the same direction as the conveying direction of the film) was 1.07 times, the residual solvent amount of the retardation film 12 was 0.02%, the average film thickness was 40 μm, the number of windings was 4000 m, and Ro0 nm and Rth were 40 nm.

<Preparation of retardation film A> (modulation of glue 2)

The above-listed ones were completely dissolved by adding, heating, and stirring in a sealed container to prepare a dope 2 .

Using a strip casting device, the dope 2 was uniformly cast on a stainless steel belt support at a temperature of 35 ° C and a width of 1800 mm, and the solvent was evaporated to a residual amount of the solvent until the residual solvent amount became 100%. The body was peeled off, and the peeled cellulose ester web was evaporating at 90 ° C and 140 ° C, slitting at a width of 1750 mm, and then applying a handling tension and extending 1.15 times at 100 ° C in the MD direction, with a tenter in TD. The direction was extended by 1.05 times, and the amount of residual solvent at the start of stretching was 3%. Then, the drying zone was dried at 100 ° C with a plurality of rollers, and the film was finished to be slit at a width of 1500 mm, and a width of 15 mm was applied to both ends of the film. The embossing process having an average height of 10 μm was wound around a 6-inch inner diameter core by winding an initial tension of 220 N/m and a final tension of 110 N/m to obtain a retardation film A. The retardation film A had a residual solvent amount of 0.1%, an average film thickness of 80 μm, and a number of turns of 4000 m. The retardation film A was Ro100 nm, Rth-120 nm, and Nz-0.7, and the slow phase axis was the TD direction.

<Preparation of retardation film B>

In addition to the use of glue 2 for tape casting. Stripping. After drying, the slit was stretched at a width of 1,650 mm, and the conveyance tension was extended by 1.05 times at 100 ° C in the MD direction, and then the same operation as the retardation film A was carried out except that the tenter was stretched 1.15 times in the TD direction to obtain a phase difference. Film B. The amount of residual solvent of the retardation film B was 0.1%, the average film thickness was 80 μm, the number of windings was 4000 m, Ro100 nm, Rth-150 nm, and Nz-1, and the slow axis was in the MD direction.

<Preparation of retardation film C>

In addition to the use of glue 2 for tape casting. Stripping. After drying at a width of 1650 mm, the conveyance tension was extended by 1.2 times at 100 ° C in the MD direction, and then the same operation as the retardation film A was carried out except that the tenter was stretched by 1.1 times in the TD direction to obtain a retardation film. B. The amount of residual solvent of the retardation film B was 0.1%, the average film thickness was 80 μm, the number of windings was 4000 m, Ro100 nm, Rth-150 nm, and Nz-1, and the slow phase axis was the TD direction.

<Preparation of retardation film D>

In addition to the use of glue 2 for tape casting. Stripping. After drying and slitting at a width of 1,650 mm, the applied conveyance tension was extended by 1.12 times at 100 ° C in the MD direction, and then extended by 1.2 times in the TD direction by a tenter, and the same operation was performed with the retardation film A to obtain a phase difference. Film D. The amount of residual solvent of the retardation film D was 0.1%, the average film thickness was 80 μm, the number of windings was 4000 m, Ro80 nm, Rth-160 nm, and Nz-1.5, and the slow phase axis was in the MD direction.

<Production of retardation film E>

In addition to the use of glue 2 for tape casting. Stripping. After drying and slitting at a width of 1,650 mm, the applied conveyance tension was extended by 1.3 times in the MD direction at 100 ° C, and then the same operation as the retardation film A was performed by stretching the tenter in the TD direction by 1.05 times to obtain a phase difference. Film E. The residual solvent amount of the retardation film E was 0.1%, and the average film thickness was 100 μm, the number of windings is 4000 m, Ro 200 nm, Rth-220 nm, Nz-0.6, and the slow phase axis is the TD direction.

<Preparation of retardation film F>

In addition to the use of glue 2 for tape casting. Stripping. After drying, the slit was stretched at a width of 1,650 mm, and the conveyance tension was extended by 1.15 times at 100 ° C in the MD direction, and then stretched by 1.02 times in the TD direction by a tenter, and the same operation was performed with the retardation film A to obtain a phase difference. Film F. The residual solvent amount of the retardation film F was 0.1%, the average film thickness was 80 μm, the number of windings was 4000 m, Ro100 nm, Rth-100 nm, and Nz-0.5, and the slow phase axis was the TD direction.

<Production of retardation film G>

In addition to the use of glue 2 for tape casting. Stripping. After drying, the slit was stretched at a width of 1,650 mm, and the conveyance tension was extended by 1.25 times at 100 ° C in the MD direction, and then extended by 1.12 times in the TD direction by a tenter, and the same operation was performed with the retardation film A to obtain a phase difference. Film G. The residual solvent amount of the retardation film G was 0.1%, the average film thickness was 80 μm, the number of windings was 4000 m, Ro100 nm, Rth-210 nm, and Nz-0.5, and the slow phase axis was the TD direction.

<Retardation film H: Production of polycarbonate film having an anthracene skeleton>

The polymerization of the polycarbonate is carried out by an interfacial polycondensation method using a conventional phosgene. In a reaction tank with a stirrer, thermometer and reflux cooler An aqueous sodium hydroxide solution and ion-exchanged water were charged, and the monomers [A] and [B] having the following configuration were dissolved in a molar ratio of 86 to 14, and a small amount of hydrogensulfite was added thereto, followed by addition thereto. Dichloromethane was blown into the phosgene at 20 ° C for about 60 minutes, and after p-tert-butylphenol was added to emulsify it, the reaction was completed by adding triethylamine at 30 ° C for about 3 hours. After the completion of the reaction, the organic phase was separated, and dichloromethane was evaporated to obtain a polycarbonate copolymer. The composition ratio of the obtained copolymer was about the same as the loading ratio.

The copolymer was dissolved in methylene chloride to prepare a dope solution having a solid content of 18% by mass, and a cast film was prepared from the dope solution to obtain an unstretched film. The amount of residual solvent of the unstretched film was 0.9% by mass. This film was stretched by two axes by appropriately adjusting the stretching ratio by an extension temperature of 225 ° C, and a retardation film H in which Ro was 100 nm, Rth was -150 nm, Nz-1, and the retardation axis was in the TD direction was produced.

<Production of retardation film I>

In addition to the use of the dope 2, tape casting, peeling, and drying were carried out, and after slitting at a width of 1,650 mm, the applied conveyance tension was extended by 1.2 times in the MD direction at 100 ° C, and then extended by 1.4 times in the TD direction by a tenter. The retardation film A performs the same operation to obtain a retardation film I. The amount of residual solvent of the retardation film I was 0.1%, the average film thickness was 160 μm, the number of turns was 4000 m, Ro was 350 nm, Rth was -525 nm, Nz was -1, and the slow axis was the TD direction.

<Production of Cellulose Ester Film 1> (modulation of glue 3)

In the sealed container, the above-mentioned ones were put in, heated, stirred, and completely dissolved, and filtered using an Augmentation filter paper No. 24 made of Azure filter paper to prepare a cellulose ester mixture, and a Japanese essence was used in the film forming line. The mixture was filtered by FINEMET NF made by wire.

(cerium oxide dispersion)

AEROSIL972V (made by Japan AEROSIL Co., Ltd.) 10 parts by mass

(The average particle size of primary particles is 16 nm, and the specific gravity is 90 g/liter)

80 parts by weight of ethanol

After mixing and mixing for 30 minutes with a dissolver, the mixture was dispersed by Marton's eucalyptus (emulsion apparatus), and the liquid turbidity after dispersion was 200 ppm. to In the cerium oxide dispersion, 80 parts by mass of dichloromethane was introduced, and the mixture was mixed with a dissolver for 30 minutes to prepare a cerium oxide dispersion diluent. Then, 10 parts by mass of a cerium oxide dispersion diluted solution was added to 100 parts by mass of the above cellulose ester mixture, and the mixture was thoroughly stirred to obtain a dope solution 3.

Using a strip casting device, the dope 3 was uniformly cast on the stainless steel belt support at a temperature of 32 ° C and 1800 mm width, and the solvent was evaporated by a stainless steel belt support so that the residual solvent amount became 100% from the stainless steel belt support. After peeling, the network of the peeled cellulose ester was evaporated at 35 ° C, slited at a width of 1650 mm, and then extended by 1.2 times in the TD direction by a tenter while being dried at a drying temperature of 135 ° C. It was dried, and the amount of residual solvent when the tenter was stretched at this time was 20%.

Then, while drying in a drying zone of 120 ° C and 110 ° C on a plurality of rollers, the drying was completed, and slitting was performed at a width of 1500 mm, and embossing having a width of 15 mm and an average height of 10 μm was applied to both ends of the film to take up an initial tension of 220 N. /m, the final tension of 110 N/m was wound around a 6-inch inner diameter core to obtain a cellulose ester film 1.

<Production of Cellulose Ester Film 2>

Using a strip casting device, the dope 3 was uniformly cast on the stainless steel belt support at a temperature of 32 ° C and 1800 mm width, and the solvent was evaporated by a stainless steel belt support so that the residual solvent amount became 100% from the stainless steel belt support. Peeling, the network of the peeled cellulose ester was evaporated at 35 ° C, slit at a width of 1650 mm, and then the handling tension was applied. While extending 1.2 times in the MD direction, it was dried at a drying temperature of 135 ° C, and the amount of residual solvent at the time of starting the stretching was 20%.

Then, while drying in a drying zone of 120 ° C and 110 ° C on a plurality of rollers, the drying was completed, and slitting was performed at a width of 1500 mm, and embossing having a width of 15 mm and an average height of 10 μm was applied to both ends of the film to take up an initial tension of 220 N. /m, the final tension of 110 N/m was wound around a 6-inch inner diameter core to obtain a cellulose ester film 2.

"The production of polarizing plates"

The polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 kg of an aqueous solution containing 1 kg of iodine and 4 kg of boric acid, and was extended by 6 times in the longitudinal direction at 50° C. to prepare a polarizer having an absorption axis in the longitudinal direction of a film thickness of 25 μm. A commercially available cellulose ester film KC8UX (manufactured by Konica Minolta Opto Co., Ltd.) which is alkalized on one side of the polarizer, and a phase difference film 1, 3 to 10 which are alkalized in the same manner on the other side. The roll of the completely alkalized polyvinyl alcohol 5% aqueous solution was used as an adhesive to form a polarizing plate 1 and 3 to 10 with a second retardation layer. The conditions of the alkalization treatment were as follows. Said.

<alkali treatment>

The film samples were subjected to the steps of alkalization, water washing, neutralization, and water washing under the above conditions, followed by drying at 80 °C.

Next, in place of the above-mentioned commercially available cellulose ester film KC8UX, KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) was used, and a commercially available cellulose ester film KC4UE (manufactured by Konica Minolta Opto Co., Ltd.) was used instead of the retardation film 1, 3. In the same manner as ~10, the polarizing plate 11 was produced.

In the same manner, a polarizing plate 12 of a commercially available cellulose ester film KC8UX was attached only to one side of the polarizer.

"Production of Liquid Crystal Display Devices" [Examples] (Example 1)

On the retardation film 1 side of the second retardation layer of the polarizing plate 1 to be produced, the retardation film A to which the first retardation layer is bonded is continuously operated by using an acrylic adhesive, and a retardation layer is formed. Polarizing plate 1. From the Hitachi LCD TV Wooo W32L-H90 of the IPS mode liquid crystal display device, the pre-bonded polarizing plate is peeled off, and the glass surface of the liquid crystal cell on the backlight side is attached to the phase difference film side to be attached with a phase. In the case of the polarizing plate 1 of the difference layer, the absorption axis of the first polarizer is arranged to be orthogonal to the direction of the slow axis of the liquid crystal layer in the black display, and the glass surface of the liquid crystal cell on the viewing side is disposed. When the KC4UE is connected and the absorption axis direction of the second polarizer is parallel to the slow axis direction of the liquid crystal layer in the black display of the liquid crystal cell, the polarizing plate 11 is bonded to form a liquid crystal display device. 1. The configuration and arrangement of the polarizing plate and the liquid crystal cell are as shown and arranged in FIG.

(Example 2)

Corona treatment was performed on one surface of the retardation film B as the first retardation layer, and the treated surface and the side of the polarizing plate 12 to which the cellulose ester film was not bonded were used, and the fully alkalized polyvinyl alcohol 5 was used. The % aqueous solution is bonded as a binder in a continuous operation, and the retardation film 2 which is bonded to the second retardation layer by continuous operation on the retardation film B by an acrylic adhesive is used to form a retardation film. In the polarizing plate 2, the liquid crystal display device 2 was produced in the same manner as in the case of using the polarizing plate 2 with the retardation layer instead of the polarizing plate 1 with the retardation layer of the first embodiment. The configuration and arrangement of the polarizing plate and the liquid crystal cell are as shown and arranged in FIG. 2 .

(Example 3) [Modulation of Coating Liquid 1]

The above was put into a sealed container, and it was completely dissolved by stirring, and it was set as the coating liquid 1.

[Production of laminated retardation layer 3]

On the cellulose ester film 1, the coating liquid 1 is extruded and a coater is used. The coating was carried out and dried at 50 ° C while being conveyed to form an MS resin layer. Then, while applying heat to 100 ° C, the conveyance tension was applied, and the film was stretched 1.2 times in the MD direction, and then stretched by 1.1 times in the TD direction using a tenter, and then dried in a drying zone of 80 ° C by a plurality of rollers. Finishing, slitting at a width of 1500 mm, applying embossing with a width of 15 mm and an average height of 10 μm at both ends of the film, and winding the initial tension of 220 N/m and the final tension of 110 N/m around the inner diameter of the 6-inch core. A laminated retardation layer 3 is obtained. The average retardation of the laminated retardation layer was 58 μm, and the number of windings was 4000 m. In the retardation layer, Ro of the cellulose layer was 0 nm, Rth was 100 nm, and Ro of the MS resin layer was 100 nm, Rth was -150 nm, and Nz was - 1, the slow phase axis is the TD direction.

The laminated retardation layer 3 produced is subjected to an alkalization treatment, and is bonded to the side of the polarizing plate 12 on which the cellulose ester layer is not bonded to the cellulose ester film, and the cellulose ester layer is bonded to the polarizer. A polarizing plate 3 with a phase difference layer was formed by laminating a 5% aqueous solution of a modified polyvinyl alcohol as an adhesive in a continuous operation, except that the polarizing plate 3 with a retardation layer was used instead of the phase difference layer of Example 1. The liquid crystal display device 3 is produced in the same manner as the polarizing plate 1 described above.

(Example 4)

The coating liquid 1 was extruded on the cellulose ester film 2, coated with a coater, and dried at 50 ° C while being conveyed, and then stretched in the TD direction by a tenter (straight with the conveyance direction of the film). After extending 1.2 times at 100 ° C in the direction), the handling tension is applied and the MD direction is performed. 1.1 times extension, and then drying the 80 ° C drying zone with a plurality of rollers, drying it, slitting at a width of 1500 mm, and applying an embossing process with a width of 15 mm and an average height of 10 μm at both ends of the film to take up the initial tension. 220 N/m and a final tension of 110 N/m were wound around a 6-inch inner diameter core to obtain a laminated retardation layer 4. The average retardation layer of the laminated retardation layer was 60 μm, and the number of windings was 4000 m. In the retardation layer, Ro of the cellulose layer was 0 nm, Rth was 100 nm, Ro of the MS resin layer was 100 nm, Rth was -150 nm, and Nz was - 1, the slow phase axis is the MD direction.

The MS resin layer side of the laminated retardation layer 4 produced was subjected to corona treatment, and the side of the polarizing plate 12 to which the cellulose ester film was not bonded was bonded using an aqueous propylene-based adhesive to prepare a polarizing layer with a retardation layer. Board 4. The liquid crystal display device 4 was produced in the same manner as in the second embodiment except that the polarizing plate 4 with the retardation layer was used instead of the polarizing plate 2 with the retardation layer.

(Examples 5 to 9, 11, 12, 16)

The liquid crystal display devices 5 to 9, 11 were produced in the same manner as in the polarizing plate 1 of the first embodiment, except that the polarizing plate of the first retardation layer and the second retardation layer shown in Table 2 were used instead of the polarizing plate 1 of the first embodiment. 12, 16.

(Embodiment 10)

One side of the retardation film D as the first retardation layer was subjected to corona treatment, and the treated surface and the polarizing plate 12 were not bonded to the cellulose ester film, and a completely alkalized polyvinyl alcohol 5% aqueous solution was used. The adhesive is applied in a continuous operation, and further used on the retardation film D. The olefin-based adhesive is used as a retardation film 2 in which the second retardation layer is bonded to the second retardation layer, and a polarizing plate with a retardation layer is produced. The liquid crystal display device 10 was produced in the same manner as in the case of using the retardation layer-attached polarizing plate instead of the retardation layer-attached polarizing plate 1 of the first embodiment. The configuration and arrangement of the polarizing plate and the liquid crystal cell are as shown in the configuration and arrangement shown in FIG. 2 .

(Examples 13 to 15)

Liquid crystal display devices 13 to 15 having the configurations of Examples 13 to 15 shown in Table 2 were produced in the same manner as in Example 11 except that the polarizing plates of the retardation films 3, 11, and 12 were produced, and the KC4 UE of the polarizing plate 11 was replaced.

<Comparative example> (Comparative Example 1)

In place of the polarizing plate 1 used in the first embodiment, KC4UE (manufactured by Konica Minolta Opto Co., Ltd.) was used as an adhesive to continuously operate the unbonded fiber of the polarizing plate 12 using a fully alkalized polyvinyl alcohol 5% aqueous solution. A liquid crystal display device 17 having the configuration of Comparative Example 1 was produced in the same manner as in Example 1 except that a polarizing plate was formed on the side of the polyester film and the KC4UE surface side was bonded to the liquid crystal cell.

(Comparative examples 2 to 5)

The same procedure was followed except that the polarizing plate with the retardation layer of the first retardation layer and the second retardation layer described in Table 2 was used instead of the polarizing plate 1 used in Example 1, and Comparative Examples 2 to 5 were produced. Liquid crystal display Devices 18-21.

As described above, the following evaluations were performed using the liquid crystal display devices 1 to 21 produced.

"Evaluation" (front contrast)

The backlight of each liquid crystal display device was turned on in an environment of 23 ° C and 55% RH, and the measurement was performed using the EZ-Contrast 160D manufactured by ELDIM Co., Ltd., and the brightness was measured by the normal direction of the white display and the black display display screen of the liquid crystal display device. , this ratio is used as a positive comparison.

Front contrast = (luminance of white display measured by the normal direction of the display device) / (luminance of black display measured by the normal direction of the display device)

When the front contrast is more than 100, it is an excellent liquid crystal display device.

(evaluation of discrimination)

By visual inspection, it is evaluated on the basis of the following criteria.

◎: Black looks deep and vivid ○: Black looks deep, but the brightness is slightly lower △: The color is not deep, the brightness is slightly lower ×: The color is not deep, the brightness is low

The results are shown in Table 2.

From the above table, the liquid crystal display devices 1 to 16 having the configurations of the first to the sixth embodiments are excellent in front view and visibility with respect to the liquid crystal display devices 17 to 21 having the configurations of the first to fifth embodiments.

1‧‧‧1st photon

2‧‧‧1st phase difference layer

3‧‧‧2nd phase difference layer

4‧‧‧1st substrate

5‧‧‧Liquid layer

6‧‧‧2nd substrate

7‧‧‧3rd phase difference layer

8‧‧‧2nd photon

11‧‧‧Absorption axis of the first polarizer 1

12‧‧‧The phase axis of the first phase difference layer 2

13‧‧‧The retardation axis of the second phase difference layer 3

14‧‧‧The slow phase axis of the liquid crystal layer

Absorption axis of the second polarizer 8

Fig. 1 shows the configuration of a polarizing plate and a liquid crystal display device according to the present invention.

Fig. 2 is a view showing another configuration of a polarizing plate and a liquid crystal display device according to the present invention.

1‧‧‧1st photon

2‧‧‧1st phase difference layer

3‧‧‧2nd phase difference layer

4‧‧‧1st substrate

5‧‧‧Liquid layer

6‧‧‧2nd substrate

7‧‧‧3rd phase difference layer

8‧‧‧2nd photon

11‧‧‧Absorption axis of the first polarizer 1

12‧‧‧The phase axis of the first phase difference layer 2

13‧‧‧The retardation axis of the second phase difference layer 3

14‧‧‧The slow phase axis of the liquid crystal layer

Absorption axis of the second polarizer 8

Claims (5)

A liquid crystal display device of an IPS mode, an FFS mode, or an FLC mode, wherein the first polarizer, the first substrate, the liquid crystal layer, the second substrate, and the second polarizer, and the first polarizer are arranged in this order A liquid crystal display device in which a liquid crystal layer of the liquid crystal layer is aligned in parallel with a surface of the first substrate and the second substrate in a black display when the first retardation layer and the second retardation layer are disposed between the first substrate and the second retardation layer The characteristic is that the first retardation layer has a negative biaxiality, the in-plane hysteresis value Ro of the second retardation layer is 0≦Ro≦50 nm, and the hysteresis value Rth of the second retardation layer in the thickness direction is 50. ≦Rth≦300 nm, the absorption axis of the first polarizer is orthogonal to the slow axis direction of the liquid crystal layer in the black display, and in the first retardation layer and the second retardation layer, the first retardation layer is closer to the first polarizer In the sub-side, the in-plane slow axis of the first retardation layer is parallel to the absorption axis of the first polarizer, and in the first retardation layer and the second retardation layer, the second retardation layer is closer to the first polarizer In the sub-side, the in-plane slow axis of the first retardation layer is orthogonal to the absorption axis of the first polarizer, and Ro=(nx-ny)×d Rth={(nx+ny )/2-nz}×d (where nx is the refractive index in the direction of the slow phase axis in the phase difference layer, ny The refractive index in the direction of the phase axis in the phase difference layer, nz is the refractive index in the thickness direction of the phase difference layer, and d is the thickness (nm) of the phase difference layer. The liquid crystal display device of claim 1, wherein Nz of the first retardation layer defined by the following formula is -1.5≦Nz<-0.5, and Ro is 50≦Ro≦300nm, Nz=(nx- Nz) / (nx-ny) (where nx is the refractive index in the direction of the slow axis in the phase difference layer, ny is the refractive index in the direction of the phase axis in the phase difference layer, and nz is the thickness direction of the phase difference layer Refractive index). The liquid crystal display device according to claim 1 or 2, wherein the third retardation layer is disposed between the second polarizer and the second substrate, and the hysteresis value of the third retardation layer is 0≦Ro≦5 nm and conforms 0≦|Rth|<40nm. A liquid crystal display device according to claim 1 or 2, wherein the second retardation layer is made of a cellulose ester resin. The liquid crystal display device according to claim 1 or 2, wherein the first retardation layer is made of a styrene resin or a lanthanum resin.