KR101345005B1 - Polarization plate and liquid crystal display device - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides a polarizing plate suitable for a transverse electric field switching mode type liquid crystal display device, a polarizing plate which reduces color change when changing the time, and a liquid crystal display device using the same. The polarizing plate is formed of at least a first protective film, a first polarizing film, a second protective film mainly composed of a specific cellulose ester, and a rod-shaped liquid crystal oriented substantially perpendicular to the surface of the polarizing film or the second protective film. The retardation layer which fixed the orientation is a polarizing plate arrange | positioned in this order, and each retardation of the said 2nd protective film and the said retardation layer, the retardation and wavelength dispersion in the state which laminated | stacked the said 2nd protective film and the said retardation layer The characteristic is in a specific range, and the absolute value of the angle between the transmission axis of the polarizing film and the in-plane slow axis of the second protective film is in the range of 0 to 1 °.

Protective film, polarizing film, laminated retardation layer, polarizing plate, cellulose ester

Description

POLARIZATION PLATE AND LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a polarizing plate and a liquid crystal display device, and more particularly, to a polarizing plate suitable for a transverse electric field switching mode type liquid crystal display device, to a polarizing plate having reduced color change when changing time, and a liquid crystal display device using the same. .

The transverse electric field switching mode type liquid crystal display device has excellent color, contrast, viewing angle, and the like for the liquid crystal mode of another liquid crystal display, for example, TN mode, and for viewing the vertical alignment mode (VA, MVA, PVA, etc.). From the excellent effects such as the excellent display performance and the small change in luminance due to the time and the small drop in the response speed in the halftone, the so-called IPS (In Plane Switching) mode liquid crystal display is actively provided to the market. It became. As an IPS mode type liquid crystal display device, FFS (fringe field switching) mode and FLC (ferroelectric liquid crystal) mode other than what is called IPS mode are mentioned.

Conventionally, the IPS method has the feature that the liquid crystal cell itself does not need to be compensated and a wide viewing angle is obtained without a compensation film (see, for example, Patent Document 1 below).

By the way, when the polarizing plate itself used for a liquid crystal display device changed time to 45 degree direction with an absorption axis in a cross nicol state, light leakage generate | occur | produced and the phenomenon which the peripheral contrast of a liquid crystal display device fell by this occurred.

Therefore, the method of laminating | stacking the optical leakage of the polarizing plate by laminating | stacking the optical film as described, for example in following patent document 2 and following patent document 3 on a polarizing plate is proposed. However, these methods are difficult to polarize plate to roll to roll, and because a plurality of films are bonded through an adhesive layer or an adhesive layer, time and cost are increased, and problems such as lowering of transmittance and thickening of the polarizing plate occur. .

In addition, as described in Patent Document 4 below, a method in which a rod-shaped liquid crystal is vertically aligned on a support in which a retardation increasing agent is placed, and a solidified layer is provided, and as described in Patent Document 5 below, the normal direction of the disc-shaped liquid crystal is a film surface. The film orientated so that it may become parallel to is proposed. They provided the above-mentioned orientation by providing a special layer for the orientation treatment, and further subjected to a rubbing treatment and the like, and the contrast viewing angle was widened. However, films produced by these methods have problems in wavelength dispersion characteristics, and as a result, when these films are used in a liquid crystal display device, the color change when the vision is shifted from the front surface is remarkable, causing a great problem in quality. Could be made.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-131700

Patent Document 2: Japanese Patent Laid-Open No. 2006-126770

Patent Document 3: Japanese Patent Laid-Open No. 2005-31626

Patent Document 4: Japanese Patent Application Laid-Open No. 2005-265889

Patent Document 5: Japanese Patent Application Laid-Open No. 2005-309379

DISCLOSURE OF THE INVENTION <

[PROBLEMS TO BE SOLVED BY THE INVENTION]

Accordingly, it is an object of the present invention to provide a polarizing plate suitable for a transverse electric field switching mode type liquid crystal display device, a polarizing plate which reduces color change when changing vision, and a liquid crystal display device using the same.

MEANS FOR SOLVING THE PROBLEMS [

The above object of the present invention can be achieved by the following arrangement.

1. A polarizing plate having at least a first protective film, a first polarizing film, and a laminated retardation layer arranged in this order, wherein the laminated retardation layer is a second protective film containing, as a main component, a cellulose ester that satisfies the following formula (1). And a retardation layer in which the alignment of the bar-shaped liquid crystals substantially perpendicular to the plane of the polarizing film or the second protective film is fixed, and the environment of 23 ° C. and 55% RH of the second protective film and the retardation layer is laminated. Retardation Ro and Rt represented by the following formulas (3) and (4) at a wavelength of 590 nm under

2nd protective film: Ro: 30-115 nm

              Rt: 100 to 250 nm

              Rt / Ro: 1.6 to 4.4

Retardation layer: Ro: 0 to 10 nm

          Rt: -100 to -400 nm,

The laminated retardation layer has an optical axis in plane, and the retardation at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH is Ro: 30 to 105 nm, Rt: -300 to 25 nm, and the following Equation 5 , The wavelength dispersion characteristics defined by 6, 7, 8

D (Ro) 1: 0.9 to 1.0

D (Ro) 2: -9.5 to 0 nm

D (Rt) 1: 0.3 to 0.9

D (Rt) 2: -100 to -10 nm,

The absolute value of the angle which the transmission axis of the said polarizing film and the in-plane slow axis of a said 2nd protective film make is in the range of 0-1 degree, The polarizing plate characterized by the above-mentioned.

2.00≤ (X + Y) ≤2.60

(Wherein, as the degree of substitution of the acyl group of the cellulose ester, X represents the degree of acetyl group substitution and Y represents the degree of propionyl group substitution.)

Ro = (nx-ny) xd

Rt = ((nx + ny) / 2-nz) × d

(Wherein the refractive index of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer is in the slow axis direction in the plane of nx, and the refractive index in the direction orthogonal to the slow axis in the plane is ny, in the thickness direction Refractive index nz and d represent the respective thickness (nm))

D (Ro) 1 = Ro (630) / Ro (480)

D (Ro) 2 = Ro (630) -Ro (480)

D (Rt) 1 = | Rt (630) / Rt (480) |

D (Rt) 2 = Rt (480) -Rt (630)

(In formula, Ro (480), Ro (630) are the retardation Ro values at 480 nm and 630 nm, respectively, at 23 degreeC and 55% RH, and Rt (480), Rt (630) are respectively 480nm, Retardation Rt value at 630 nm)

2. Said cellulose ester satisfy | fills following formula (2), The said polarizing plate of 1 characterized by the above-mentioned.

0.10? Y?

3. The first surface of the second protective film faces the polarizing film, and the second surface of the second protective film opposite to the first surface is disposed to face the retardation layer. The polarizing plate of description.

4. Said retardation layer is arrange | positioned between said 2nd protective film and said polarizing film, The said polarizing plate of 1 characterized by the above-mentioned.

5. A liquid crystal cell in which the liquid crystal molecules are aligned in a direction substantially parallel to the glass substrate at the time of black display, the polarizing plate according to 1 above, and the alignment directions on both glass substrate sides are substantially parallel, a third protective film, and a second The third protective film has a polarizing plate constituted by a polarizing film and a fourth protective film, and the in-plane slow axis of the second protective film of the polarizing plate according to the above 1 and the alignment direction of the liquid crystal cell are substantially parallel, and the third protective film is Ro: 0 to 5 nm, Rt: -10 to 10 nm, and the third protective film has a film thickness of 20 to 45 µm.

6. Liquid crystal cell in which the liquid crystal molecule is orientated substantially parallel to a glass substrate at the time of black display, the polarizing plate of said 1, and the orientation direction on both glass substrate sides is substantially parallel, a 3rd protective film, and a 2nd It has a polarizing plate comprised of the polarizing film and the 4th protective film, The in-plane slow axis of the 2nd protective film of this polarizing plate of 1, and the orientation direction of a liquid crystal cell are orthogonal, and a 3rd protective film is Ro: 0 to 5 nm, Rt: -10 to 10 nm, and the third protective film has a film thickness of 20 to 45 µm.

EFFECTS OF THE INVENTION [

According to the present invention, it is possible to provide a polarizing plate suitable for a transverse electric field switching mode type liquid crystal display device, a polarizing plate having reduced color change when changing the time, and a liquid crystal display device using the same.

1 is a schematic diagram showing the configuration of a polarizing plate and a liquid crystal display device according to the claims.

Explanation of symbols

1: first shield

2: second shield

3: third shield

4: fourth shield

5: first polarizing film

6: second shield

7: retardation layer

8: liquid crystal cell

9, 10: glass substrate

a: polarization transmission axis of polarizing film

b: slow axis of the second protective shield

c: orientation direction of the liquid crystal cell

d: rubbing axis of glass substrate

BEST MODE FOR CARRYING OUT THE INVENTION [

EMBODIMENT OF THE INVENTION Hereinafter, although the best form for implementing this invention is demonstrated in detail, this invention is not limited to these.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining the said subject, it turns out that in a transverse electric field switching mode type | mold liquid crystal display device, it controls the wavelength dispersion characteristic of the phase difference of a phase difference plate, especially the wavelength dispersion characteristic of the phase difference of a film thickness direction. It was confirmed that it greatly influenced the color change at the time of changing, and by further examining, it came to the means which can control the color fluctuation at the dropping point of time.

A polarizing plate for a transverse electric field switching mode liquid crystal display device of the present invention includes at least a first protective film, a first polarizing film, a second protective film mainly containing a cellulose ester satisfying the following formulas (1) and (2), and the polarization. The retardation layer which fixed the orientation of the rod-shaped liquid crystal oriented substantially perpendicular to the surface of a film | membrane or a 2nd protective film is a polarizing plate arrange | positioned in this order, and the 23 degreeC and 55% RH of the said 2nd protective film and said retardation layer Retardation Ro and Rt represented by Equations 3 and 4 at a wavelength of 590 nm under the environment are respectively

2nd protective film: Ro: 30-115 nm

              Rt: 100 to 250 nm

              Rt / Ro: 1.6 to 4.4

Retardation layer: Ro: 0 to 10 nm

          Rt: -100 to -400 nm

And the retardation at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH in a state where the second protective film and the retardation layer are laminated is Ro: 30 to 105 nm, Rt: -300 to 25 nm, and laminated The obtained film has an optical axis in the same plane, and also has a wavelength dispersion characteristic defined by the following equations (5), (6), (7) and (8).

D (Ro) 1: 0.9 to 1.0

D (Ro) 2: -9.5 to 0 nm

D (Rt) 1: 0.3 to 0.9

D (Rt) 2: -100 to -10 nm

The absolute value of the angle formed by the transmission axis of the polarizing film and the in-plane slow axis of the second protective film is in the range of 0 to 1 °.

&Quot; (1) &quot;

2.00≤ (X + Y) ≤2.60

&Quot; (2) &quot;

0.10? Y?

(Wherein, as the degree of substitution of the acyl group of the cellulose ester, X represents the degree of acetyl group substitution and Y represents the degree of propionyl group substitution.)

&Quot; (3) &quot;

Ro = (nx-ny) xd

&Quot; (4) &quot;

Rt = ((nx + ny) / 2-nz) × d

(Wherein the refractive index of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer is in the slow axis direction in the plane of nx, and the refractive index in the direction orthogonal to the slow axis in the plane is ny, in the thickness direction Refractive index nz and d represent the respective thickness (nm))

&Quot; (5) &quot;

D (Ro) 1 = Ro (630) / Ro (480)

&Quot; (6) &quot;

D (Ro) 2 = Ro (630) -Ro (480)

&Quot; (7) &quot;

D (Rt) 1 = | Rt (630) / Rt (480) │

&Quot; (8) &quot;

D (Rt) 2 = Rt (480) -Rt (630)

(In formula, Ro (480), Ro (630) are the retardation Ro values at 480 nm and 630 nm, respectively, at 23 degreeC and 55% RH, and Rt (480), Rt (630) are respectively 480nm, Retardation Rt value at 630 nm)

In order to make a said 2nd protective film into the said numerical range, it is preferable to perform an extending | stretching process of the said 2nd protective film in the state which heat-processed the film. In addition, when extending | stretching by heat-processing the said cellulose ester, in order to reduce residual strain as much as possible, it extends | stretches in the direction orthogonal to a conveyance direction about 1.1 to 1.5 times in the range of about about 10 degreeC of glass transition points, or a solution It is preferable to extend | stretch the film manufactured by casting | flow_spread about 1.1 to 1.7 times in the direction which goes directly to a conveyance direction in the state which the amount of residual solvents remaining about 2-100 mass%. In addition, in order to make the said retardation layer into the said range, it is preferable to perform the film thickness control of a retardation layer, the temperature at the time of ultraviolet hardening, the tilt angle control, and the pretilt angle control in an air interface with a support body. In particular, film thickness control and temperature at the time of hardening have a big influence on retardation control. Moreover, although the vertical alignment film may be used for the orientation of a liquid crystal, in this invention, since the pretilt angle of a liquid crystal material and an air interface reaches to a base side, a special alignment film is not needed.

Moreover, in order to make the retardation of the laminated retardation layer which laminated | stacked the said 2nd protective film and the said phase difference layer into the said numerical range, each of the 2nd protective film and the phase difference layer was controlled, controlling Ro of the 2nd protective film with the said means. This can be achieved by controlling the phase difference as viewed in the oblique direction. It is preferable to control the phase difference of the inclination direction of a 2nd protective film on extending | stretching conditions at the time of manufacturing the said 2nd protective film. In order to reduce the phase difference based on the in-plane fastening axis of the second passivation film, it can be achieved by increasing the draw ratio or lowering the draw temperature. It is preferable to control the retardation of the inclination direction of the said retardation layer by the film thickness of the said retardation layer and the temperature at the time of hardening. In order to reduce the retardation in the oblique direction, it can be achieved by making the film thickness thin or raising the temperature during curing. Rt can be calculated from the sum of the phase differences in the oblique directions and the in-plane phase differences based on these fast axis.

In addition, it is preferable that D (Ro) 1 and D (Ro) 2 appropriately select a material and a manufacturing method of the second protective film as the means for controlling the wavelength dispersion. As for the material, these values can be achieved by changing the substituent (type and degree of substitution) with a cellulose ester-based material. In the case of only the acetyl group, the lower the degree of substitution, the larger the value, and the larger the propionyl group, the smaller the tendency. It also depends on the additive. In the case of the retardation increasing agent described in patent document 3 etc., there exists a tendency for it to become large. D (Rt) 1 and D (Rt) 2 can be achieved by controlling respective phase differences between the second protective film and the retardation layer. Specifically, it becomes a small value by making the phase difference of a 2nd protective film relatively large.

In the present invention, the absolute value of the angle formed by the transmission axis of the first polarizing film and the in-plane slow axis of the second protective film is in a range of 0 to 1 °, but this is an in-plane slow axis of the second protective film. It can achieve by controlling in-plane nonuniformity, making it into a conveyance direction and a direct direction. For this purpose, it is preferable to precisely control the balance of the stretching temperature and the stretching ratio, and to control the stretching portion (clip of tenter, etc.) independently on both sides of this protective film. This can be achieved by adjusting the stretching temperature and the stretching magnification with respect to the clip position and the stress of the clip.

In addition, in the liquid crystal display device of the present invention, the liquid crystal molecules are oriented substantially in a direction parallel to the glass substrate at the time of black display, which is a characteristic of the polarizing plate of the present invention and the IPS mode type liquid crystal cell, and the alignment direction on both glass substrate sides is In-plane slow axis of the 2nd protective film of the polarizing plate which has a liquid crystal cell substantially parallel, and the polarizing plate comprised by the 3rd protective film, the 2nd polarizing film, and the 4th protective film, The orientation direction of a liquid crystal cell is substantially parallel or orthogonal, and a 3rd protective film is Ro: 0-5 nm, Rt: -10-10 nm, and the film thickness of a 3rd protective film is 20-45 micrometers. A transverse electric field switching mode type liquid crystal display device.

In other words, by controlling the retardation of the second passivation film and the retardation layer in a specific range, and further reducing the retardation Ro and Rt of the third passivation film to make it thinner, the effect of expanding the viewing angle of the transverse electric field switching mode liquid crystal display device is reduced. In addition, the color change can be significantly suppressed, and in the past, the color change at the time of black display was remarkable, but it could be greatly reduced.

In order to make the retardation of a said 3rd protective film into the said numerical range, if a 3rd protective film is a cellulose ester, it may be manufactured by melt film forming, or it may hold | maintain 15 seconds or more at the temperature more than a glass transition point in the middle of solution film forming, or cellulose It is preferable to add an additive having a birefringence expression opposite to that of the ester. Moreover, if it is a cycloolefin type film, it is preferable to use the film manufactured by melting or solution casting, as it is, without performing extending | stretching process.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated about the detail of each element.

(Measurement of retardation)

The measurement of the retardation which concerns on this invention can be performed in 23 degreeC and 55% of environments using KOBRA 21ADH made from Oji Keisukukiki as an example. In addition, when calculating the retardation of the thickness direction, the value which measured the refractive index of the corresponding wavelength of each layer using the Abbe refractometer is used. In addition, in the case of a laminated body, the average value of the refractive index of each layer is used.

Samples in which the retardation in the thickness direction of the laminate in the present invention has a negative value are calculated by measuring the retardation when the in-plane fastening axis of the laminate is inclined and 40 degrees inclined when calculating the retardation. It was decided to use.

(Configuration of Polarizing Plate and Liquid Crystal Display Device)

The configuration of a polarizing plate and a liquid crystal display device of the present invention will be described with reference to the drawings.

1A is a configuration of a polarizing plate and a liquid crystal display device according to claim 5.

From the viewing side, the polarizing plate on the viewing side is comprised by the phase difference layer 7 which fixed the orientation of the 1st protective film 1, the 1st polarizing film 5, the 2nd protective film 2, and the rod-shaped liquid crystal, The polarizing plate is bonded to the liquid crystal cell 8 sandwiched by the glass substrates 9 and 10. Moreover, the polarizing plate comprised by the 3rd protective film 3, the 2nd polarizing film 6, and the 4th protective film 4 is arrange | positioned on the surface on the opposite side to the said liquid crystal cell 8.

The in-plane slow axis (b) of the second protective film and the alignment direction (c) of the liquid crystal cell are parallel. The polarization transmission axis (a) of a polarizing film and the rubbing axis (d) of a glass substrate are in the direction shown by drawing. In the figure, the retardation layer 7 may be disposed between the first polarizing film 5 and the second protective film 2.

FIG. 1B is a configuration of a polarizing plate and a liquid crystal display device according to claim 6.

The liquid crystal cell which comprises the polarizing plate by the 4th protective film 4, the 2nd polarizing film 6, and the 3rd protective film 3 from the visual recognition side, and the said polarizing plate clamped by the glass substrates 9 and 10. It is bonded to (8). Moreover, on the surface opposite to the said liquid crystal cell 8, the phase difference layer 7 which fixed the orientation of the rod-shaped liquid crystal, the 2nd protective film 2, the 1st polarizing film 5, and the 1st protective film ( The polarizing plate comprised by 1) is arrange | positioned.

The in-plane slow axis (b) of the second protective film and the alignment direction (c) of the liquid crystal cell are orthogonal to each other. The polarization transmission axis (a) of a polarizing film and the rubbing axis (d) of a glass substrate are in the direction shown by drawing. In the figure, the retardation layer 7 may be disposed between the first polarizing film 5 and the second protective film 2.

(Phase difference layer)

The polarizing plate of this invention apply | coats a liquid crystal (or solution of liquid crystal) to a base material, performs drying and heat processing (also called an orientation process), fixs liquid crystal orientation by ultraviolet curing or thermal polymerization, etc., and is a substantially vertically aligned film It is characterized by having a phase difference layer by a large liquid crystal. The retardation layer is formed on the first polarizing film or the second protective film as a base material, but is preferably formed on the second protective film.

In the case of evaluating using the polarization microscope to evaluate the optical phase difference of the obtained liquid crystal aligning layer, the vertical alignment here appears black when the liquid crystal aligning layer is sandwiched between the cross nicol polarizers and the liquid crystal alignment layer between the cross nicol polarizers. When it is tilted, the transmission of light is defined as being vertically oriented.

When forming a liquid crystal aligning layer, what is called a vertical alignment film can also be used, and there is no restriction | limiting in particular as a vertical alignment film, When the liquid crystal material itself orientates vertically at an air interface, when the orientation regulating force reaches even the interface opposite to an air interface, The alignment film is not particularly required, and the alignment film is also preferable in terms of simplifying the configuration. When using a vertical alignment film, it is also preferable to use the alignment film containing the crosslinked body of the block polymer composition containing the (meth) acrylic-type block polymer described in Unexamined-Japanese-Patent No. 2005-148473 etc., and the like.

The retardation layer according to the present invention is a retardation layer by a substantially vertically oriented rod-shaped liquid crystal in which retardation Ro is in a range of 0 to 10 nm and Rt of -100 to -400 nm. In addition, Ro is more preferably in the range of 0 to 5 nm. In order to make the said retardation layer into the said range, it is preferable to control the film thickness of a retardation layer, the temperature at the time of ultraviolet hardening, the tilt angle control, and the pretilt angle control in an air interface with a support body.

The retardation layer is formed by curing a liquid crystal material capable of becoming a liquid crystal phase at a predetermined temperature with a predetermined liquid crystal regularity. The upper limit of the temperature indicating the liquid crystal phase is not particularly limited as long as the transparent resin film of the substrate is not damaged. Specifically, from the viewpoint of ease of control of the process temperature and the maintenance of dimensional accuracy, 120 ° C. or less is preferable, and more preferably a liquid crystal material that becomes a liquid crystal phase at a temperature of 100 ° C. or less is preferably used. On the other hand, the minimum of the temperature which shows a liquid crystal phase can be called the temperature at which a liquid crystal material can maintain an orientation state, when using as a retardation plate.

It is preferable to use a polymeric liquid crystal material as a liquid crystal material used as a retardation plate which concerns on this invention. The polymerizable liquid crystal material can be polymerized by irradiation with a predetermined actinic radiation, and since the orientation state is fixed in the polymerized state, the lower limit of the temperature for forming the liquid crystal phase is not particularly limited when the polymerizable liquid crystal material is used. .

As the polymerizable liquid crystal material, any one of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, or a polymerizable liquid crystal polymer may be used, or may be mixed with each other and used. Since the polymerizable liquid crystal material can fix the alignment state, the alignment of the liquid crystal can be easily performed at low temperature, and since the alignment state is fixed in use, the polymerizable liquid crystal material can be used regardless of the use conditions such as temperature. have.

Especially as said polymerizable liquid crystal material, a polymerizable liquid crystal monomer is used preferably. This is because the polymerizable liquid crystal monomer can be oriented at a lower temperature than the polymerizable liquid crystal oligomer or the polymerizable liquid crystal polymer and is easy to be oriented in terms of high sensitivity in the alignment.

As a specific polymeric liquid crystal monomer, the rod-like liquid crystalline compound (I) represented by following formula (1), and the rod-like liquid crystalline compound (II) represented by following formula (2) are mentioned. As the rod-like liquid crystalline compound (I), two or more kinds of the compounds contained in the formula (1) may be mixed and used, and as the rod-like liquid crystalline compound (II), two or more kinds of the compounds included in the formula (2) may be mixed and used. It may be. Moreover, 1 or more types of rod-shaped liquid crystalline compounds (I) and 1 or more types of rod-shaped liquid crystalline compounds (II) can also be mixed and used.

In the general formula (1) representing the rod-like liquid crystal compound (I), R ¹ and R ² each represent a hydrogen atom or a methyl group, but R ¹ and R ² together represent a hydrogen atom because the temperature range representing the liquid crystal phase is wide. desirable. X does not interfere with any of a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group, but is preferably a chlorine atom or a methyl group. In addition, a and b which represent chain length of the (meth) acryloyloxy group of the both ends of the molecular chain of rod-shaped liquid crystalline compound (I), and the alkylene group which is a spacer with an aromatic ring, respectively are arbitrary in the range of 2-12 Although the integer of can be taken, it is preferable that it is the range of 4-10, and it is more preferable that it is the range of 6-9. The compound of Formula 1 having a = b = 0 is not only susceptible to hydrolysis due to lack of stability, but also has high crystallinity of the compound itself. In addition, compounds of Formula 1, wherein a and b are each 13 or more, have a low isotropic transition temperature (TI). For this reason, neither of these compounds has a narrow temperature range in which liquid crystallinity is exhibited.

The rod-like liquid crystalline compound (I) can be synthesized by any method. For example, the rod-like liquid crystalline compound (I) in which X is a methyl group can be obtained by esterification of 1 equivalent of methylhydroquinone and 2 equivalents of 4- (m- (meth) acryloyloxyalkoxy) benzoic acid. have. As for esterification, it is customary to activate the said benzoic acid with acid chloride, sulfonic anhydride, etc., and to react this with methylhydroquinone. In addition, a carboxylic acid unit and methylhydroquinone can also be directly reacted using a condensing agent such as DCC (dicyclohexylcarbodiimide). As a method other than this, the esterification reaction of 1 equivalent of methylhydroquinone and 2 equivalent of 4- (m-benzyloxyalkoxy) benzoic acid is first performed, and then the obtained ester is debenzylated by a hydrogenation reaction or the like, followed by molecular Rod-shaped liquid crystalline compound (I) can also be synthesize | combined by the method of acryloylating the terminal. In the esterification reaction of methylhydroquinone with 4- (m-benzyloxyalkoxy) benzoic acid, methylhydroquinone may be introduced into diacetate and then reacted with the benzoic acid in a molten state to obtain an ester directly. The rod-like liquid crystalline compound (I) when X in the formula (1) is not a methyl group can also be obtained by carrying out the same reaction as described above using a hydroquinone having a corresponding substituent instead of methylhydroquinone.

In the general formula (2) representing the rod-like liquid crystal compound (II), R ³ represents a hydrogen atom or a methyl group, but R ³ is preferably hydrogen because the temperature range representing the liquid crystal phase is wide. Speaking about c which shows the chain length of an alkylene group, the rod-shaped liquid crystalline compound (II) whose value is 2-12 does not show liquid crystalline. However, in consideration of compatibility with the rod-like liquid crystalline compound (I) having liquid crystallinity, c is preferably in the range of 4 to 10, and more preferably in the range of 6 to 9. Rod-shaped liquid crystalline compound (II) can also be synthesize | combined by arbitrary methods, for example, ester of 1 equivalent of 4-cyanophenol and 1 equivalent of 4- (n- (meth) acryloyloxyalkoxy) benzoic acid Rod-shaped liquid crystalline compound (II) can be synthesize | combined by a oxidization reaction. This esterification reaction generally activates the benzoic acid with an acid chloride, a sulfonic anhydride, or the like, in the same manner as in the case of synthesizing the rod-like liquid crystalline compound (I), and reacts this with 4-cyanophenol. Moreover, the said benzoic acid and 4-cyanophenol can be made to react using condensing agents, such as DCC (dicyclohexyl carbodiimide).

In addition to the above, in this invention, a polymeric liquid crystal oligomer, a polymeric liquid crystal polymer, etc. can be used. As such a polymeric liquid crystal oligomer and a polymeric liquid crystal polymer, what is conventionally proposed can be selected suitably and can be used.

In this invention, in addition to a polymeric liquid crystal material, you may use a photoinitiator as needed. Although a photoinitiator may be unnecessary when superposing | polymerizing a polymeric liquid crystal material by electron beam irradiation, in the case of hardening by the ultraviolet-ray (UV) irradiation which is generally used, a photoinitiator is normally used for a polymerization promotion. Because it becomes.

As a photoinitiator, benzyl (also called bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, benzoyl benzoate, 4-benzoyl-4'-methyldiphenyl sulfide, benzyl methyl ketal , Dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, p-dimethylaminobenzoic acid isoamyl, 3,3'-dimethyl-4-methoxybenzophenone, methylbenzoylformate, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1 -One, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane- 1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-di Isopropyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, or 1 -Chloro-4-propoxy thioxanthone, etc. are mentioned. As addition amount of a photoinitiator, generally 0.01%-20% are preferable, More preferably, they are 0.1%-10%, More preferably, add to the polymeric liquid crystal material of this invention in 0.5%-5% of range. can do. Moreover, in addition to a photoinitiator, it is also possible to add a sensitizer in the range which does not impair the objective of this invention.

It is preferable that it is in the range of 0.1 micrometer-20 micrometers, and, as for the film thickness of the liquid crystal layer in this invention, it is more preferable to exist in the range which is 0.2-10 micrometers. When the liquid crystal layer according to the present invention becomes thicker than the above range, more than necessary optical anisotropy is produced, and when it is thinner than the above range, predetermined optical anisotropy may not be obtained. Therefore, what is necessary is just to determine the film thickness of a liquid crystal layer based on required optical anisotropy.

A polymeric liquid crystal material mix | blends a photoinitiator, a sensitizer, etc. as needed, manufactures and uses the composition for liquid crystal layer formation, coats on a base material, and forms the layer for liquid crystal layer formation. As a method of forming the liquid crystal layer forming layer, for example, a method of forming a dry film or the like and stacking the liquid crystal layer forming layer on a substrate or melting the liquid crystal layer forming composition is applied onto the substrate. It is also possible to take a method, etc., but in the present invention, a solvent is added as a composition for forming the liquid crystal layer, and the liquid crystal layer forming layer is coated by using a coating composition in which other components are dissolved, and then removing the solvent. It is preferable to form This is a simple process in comparison with other methods.

The solvent is not particularly limited as long as it is a solvent capable of dissolving the above-mentioned polymerizable liquid crystal material and the like and does not lower the properties of the transparent resin film. Specifically, benzene, toluene, xylene, n-butylbenzene, diethyl Hydrocarbons such as benzene and tetralin; Ethers such as methoxybenzene, 1,2-dimethoxybenzene and diethylene glycol dimethyl ether; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or 2,4-pentanedione; Esters such as ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, or γ-butyrolactone; Amide solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide, or dimethylacetamide; Halogen solvents such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene or orthodichlorobenzene; alcohols such as t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, or butyl cellosolve; One or two or more kinds of phenols such as phenol and parachlorophenol can be used.

Using only a single kind of solvent may result in insufficient solubility of the polymerizable liquid crystal material and the like, and the substrate may be eroded as described above. However, this problem can be avoided by mixing two or more kinds of solvents. Among the above solvents, preferred solvents are hydrocarbon solvents and glycol monoether acetate solvents, and preferred solvents are mixed solvents of ethers or ketones with glycols. Since the concentration of the solution depends on the solubility of the polymerizable liquid crystal material and the like and the film thickness of the liquid crystal layer to be produced, it cannot be uniformly defined, but usually 1% to 60% is preferable, and more preferably 3% To 40% range.

The compound of that excepting the above can be added to the composition for liquid crystal layer formation used for this invention within the range which does not impair the objective of this invention. As a compound which can be added, For example, Polyester (meth) acrylate obtained by making (meth) acrylic acid react with the polyester prepolymer obtained by condensing polyhydric alcohol, monobasic acid, or polybasic acid; Polyurethane (meth) acrylates obtained by reacting a compound having a polyol group and two isocyanate groups with each other and then reacting (meth) acrylic acid with the reaction product thereof; Bisphenol A type epoxy resin, Bisphenol F type epoxy resin, Novolak type epoxy resin, Polycarboxylic acid polyglycidyl ester, Polyol polyglycidyl ether, Aliphatic or alicyclic epoxy resin, Amine epoxy resin, Triphenol methane type Photopolymerizable compounds, such as epoxy (meth) acrylate obtained by making epoxy resin, such as an epoxy resin and a dihydroxy benzene type epoxy resin, and (meth) acrylic acid react, or a photopolymerizable liquid crystalline compound which has an acryl group or a methacryl group, etc. Can be mentioned. The addition amount of these compounds with respect to the composition for liquid crystal layer formation of this invention is chosen in the range which does not impair the objective of this invention, Generally it is preferable that it is 40% or less of the composition for liquid crystal layer formation of this invention, More preferably, Is 20% or less. By addition of these compounds, sclerosis | hardenability of the liquid crystal material in this invention improves, the mechanical strength of the liquid crystal layer obtained increases, and its stability improves.

Moreover, in order to make coating easy, surfactant etc. can be added to the composition for liquid-crystal layer formation which mix | blended the solvent. Examples of the surfactant that can be added include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides and polyamine derivatives; Polyoxy ethylene-polyoxypropylene condensates, primary or secondary alcohol ethoxylates, alkylphenolethoxylates, polyethylene glycols and esters thereof, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl substituted aromatic sulfonic acids Anionic surfactants such as salts, alkylphosphates, aliphatic or aromatic sulfonic acid formalin condensates; Amphoteric surfactants such as laurylamide propyl betaine and lauryl amino acetate betaine; Nonionic surfactants such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamines; Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkylethylene oxide adduct, perfluoroalkyltrimethylammonium salt, perfluoroalkyl group, hydrophilic group-containing oligomer, perfluoroalkyl-lipophilic group-containing oligomer purple Fluorine-type surfactants, such as a fluoroalkyl group containing urethane, etc. are mentioned. The amount of the surfactant added varies depending on the kind of the surfactant, the kind of the liquid crystal material, the kind of the solvent, and also the kind of the alignment film to coat the solution, but usually 10 ppm to 10% of the polymerizable liquid crystal material contained in the solution. It is preferable, More preferably, it is 100 ppm-5%, More preferably, it is 0.1 to 1% of range.

As a method for coating the composition for forming a liquid crystal layer, a spin coating method, a roll coating method, a printing method, an immersion pulling method, a die coating method, a casting method, a bar coating method, a blade coating method, a spray coating method, a gravure coating method, and a reverse A coating method or an extrusion coating method. As a method of removing a solvent after coating the composition for liquid crystal layer formation, it is performed by air drying, heat removal, or reduced pressure removal, the method which combined these etc., for example. The solvent is removed to form a layer for forming a liquid crystal layer.

In the step of curing the polymerizable liquid crystal material, energy for curing the polymerizable liquid crystal material is provided and may be thermal energy, but is usually performed by irradiation with ionizing radiation having the ability to cause polymerization. If necessary, a polymerization initiator may be included in the polymerizable liquid crystal material. The ionizing radiation is not particularly limited as long as it is radiation capable of polymerizing the polymerizable liquid crystal material, but usually ultraviolet light or visible light is used in view of ease of use of the device, and light having a wavelength of 150 to 500 nm is preferable. More preferably, it is 250-450 nm, More preferably, it is an ultraviolet-ray of 300-400 nm wavelength.

In this invention, the method of irradiating an ultraviolet-ray (UV) as active radiation and generating a radical from a polymerization initiator with an ultraviolet-ray is made to perform radical polymerization. This is because the method of using UV as the actinic radiation is an already established technique, and thus it is easy to apply to the present invention including the polymerization initiator to be used.

As a light source for irradiating this ultraviolet light, a low pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), a high pressure discharge lamp (high pressure mercury lamp, a metal halide lamp), or a short arc discharge lamp (ultra high pressure mercury lamp, xenon lamp, Mercury xenon lamps). Among them, the use of metal halide lamps, xenon lamps, high pressure mercury lamps and the like is encouraged. What is necessary is just to adjust irradiation intensity suitably with the composition of a polymeric liquid crystal material which forms a liquid crystal layer, and a photoinitiator.

Orientation fixation process by irradiation of active radiation may be performed at the process temperature in the process of forming the liquid crystal layer formation layer mentioned above, ie, the temperature condition which a polymeric liquid crystal material becomes a liquid crystal phase, and is lower than the temperature which becomes a liquid crystal phase You can also do The polymerizable liquid crystal material, which has once become a liquid crystal phase, does not suddenly disturb the alignment state even if the temperature is subsequently lowered.

(materials)

In this invention, as a base material used for the 1st-4th protective film, what is easy to manufacture, an optically transparent thing, etc. is preferable, and it is especially preferable that it is a transparent resin film.

The transparent in the present invention refers to a visible light transmittance of 60% or more, preferably 80% or more, and particularly preferably 90% or more.

Although it will not specifically limit if it has the said property, For example, cellulose ester film, such as a cellulose diacetate film, a cellulose triacetate film, a cellulose acetate propionate film, a cellulose acetate butyrate film, a polyester film, and a polycarbonate film , Polyarylate film, polysulfone (including polyether sulfone) film, polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol Film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, norbornene-based resin film, polymethylpentene film, polyetherketone film, polyetherketoneimide film, polyamide film, fluororesin peel , There may be mentioned a nylon film, polymethyl methacrylate film, an acrylic film or a glass plate or the like. Especially, a norbornene-type resin film and a cellulose ester-type film are preferable.

The norbornene-based resin film preferably used in the present invention is an amorphous polyolefin film having a norbornene structure, for example, APO manufactured by Mitsui Seki Oil Chemical Co., Ltd., Xeonex manufactured by Nihon Xeon Co., Ltd., ARTON made by JSR Corporation.

In the 1st-4th protective film which concerns on this invention, it is preferable to use a cellulose ester type film among these, Especially the base material of a 2nd protective film is a cellulose ester type film which has a specific cellulose ester mentioned later as a main component. As cellulose ester, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate is preferable, and cellulose acetate and cellulose acetate propionate are used especially preferably. Commercially available cellulose ester films include, for example, Konica Minolta Tag KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR, KC8UY-HA, and KC8UX-RHA (Octano Co., Ltd.). ) And the like are preferably used in terms of manufacturing, cost, transparency, adhesiveness and the like. These films may be a film manufactured by melt casting film forming, or may be a film manufactured by solution casting film forming.

<Cellulose Ester>

The cellulose ester used for the 2nd protective film which concerns on this invention is demonstrated in detail.

The cellulose ester used for the second protective film according to the present invention is preferably an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester or an aromatic carboxylic acid ester or a mixed ester of an aliphatic carboxylic acid ester and an aromatic carboxylic acid ester having about 2 to 22 carbon atoms. In particular, it is preferable that it is a lower fatty acid ester of cellulose. Lower fatty acids in lower fatty acid esters of cellulose mean fatty acids having 6 or less carbon atoms. Specifically, it is described in cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, and the like, and described in JP-A-10-45804, JP-A-8-231761, US Patent No. 2,319,052, and the like. Mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, and the like. Among the above base materials, the lower fatty acid ester of cellulose that is particularly preferably used is cellulose acetate propionate.

The cellulose ester has a acyl group having 2 to 22 carbon atoms as a substituent, and when the degree of substitution of the acetyl group is X and the degree of substitution of the propionyl group is Y, cellulose satisfying the following formulas (1) and (2) simultaneously: Ester.

&Quot; (1) &quot;

2.00? X + Y? 2.60

&Quot; (2) &quot;

0.10? Y?

Especially, 2.30 <= X + Y <2.55 is preferable and 2.40 <= X + Y <2.55 is more preferable. Further, 0.50? Y? 0.90 is preferable, and 0.70? Y? 0.90 is more preferable.

The part not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by a known method. The degree of substitution of these acyl groups can be measured according to the method defined in ASTM-D817-96.

The cellulose ester may be used alone or in combination with a cellulose ester synthesized from cotton linter, wood pulp, kenaf, or the like as a raw material. In particular, cotton linter (hereinafter simply referred to as linter) and cellulose ester synthesized from wood pulp are preferably used alone or in combination.

The cellulose esters obtained therefrom may be mixed and used in an arbitrary ratio. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), these cellulose esters use organic solvents such as acetic acid or methylene chloride, and a protic catalyst such as sulfuric acid. It can obtain by making it react by a conventional method.

In the case of acetyl cellulose, it is necessary to extend the time of the acetization reaction in order to increase the acetization rate. However, if the reaction time is taken too long, decomposition proceeds simultaneously, resulting in breakage of the polymer chain, decomposition of the acetyl group, and the like, resulting in undesirable results. Therefore, in order to increase the degree of acetalization and to suppress decomposition to some extent, it is necessary to set the reaction time within a certain range. It is not appropriate to define the reaction time because the reaction conditions vary, and the reaction conditions, equipment and other conditions greatly change. Since the decomposition of the polymer proceeds as the molecular weight distribution increases, the degree of decomposition can be defined by the value of the weight average molecular weight (Mw) / number average molecular weight (Mn) that is usually used even in the case of cellulose esters. In other words, in the acetonitrile process of cellulose triacetate, the weight average molecular weight (Mw) / number average used as one indicator of the degree of reaction for carrying out the acetization reaction for a sufficient time without being excessively decomposed. The value of molecular weight (Mn) can be used.

It is preferable that the value of ratio Mw / Mn of the weight average molecular weight (Mw) and number average molecular weight (Mn) of the cellulose ester used for this invention is 1.4-3.0. In addition, in this invention, although the cellulose ester film should just contain the cellulose ester whose Mw / Mn value is 1.4-3.0 as a material, the cellulose ester (preferably cellulose triacetate or cellulose acetate propionate) contained in a film whole More preferably, the value of Mw / Mn is in the range of 1.4 to 3.0. It is difficult to make it less than 1.4 in the synthesis | combination process of a cellulose ester, and it can obtain a cellulose ester with a uniform molecular weight by fractionating by gel filtration. However, this method is costly. When it is 3.0 or less, planarity is easily maintained, which is preferable. More preferably, it is 1.7 to 2.2.

It is preferable to use the thing of 80000-200000 as a number average molecular weight (Mn) for the molecular weight of the cellulose ester used for this invention. More preferably from 100000 to 200000, and particularly preferably from 150000 to 200000.

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

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.) were connected and used)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard polystyrene STK A calibration curve of 13 samples with standard polystyrene (manufactured by Tosoh Corporation) Mw = 1,000,000 to 500 was used. The 13 samples are preferably used at substantially equal intervals.

The manufacturing method of a cellulose ester can be obtained by the method of Unexamined-Japanese-Patent No. 10-45804.

In addition, the cellulose ester is also affected by the trace metal component in the cellulose ester. Although these are considered to be related to water used in the manufacturing process, it is preferable that fewer components can be insoluble nuclei, and metal ions such as iron, calcium and magnesium may contain organic acid groups. Insoluble matters may be formed by forming a salt with a salt, and the like is preferable. It is preferable that it is 1 ppm or less about an iron (Fe) component. About calcium (Ca) component, it is contained a lot in ground water or river water, and if it is large, it becomes hard water and it is inadequate as a drink, but it forms acidic components, such as carboxylic acid and sulfonic acid, and also forms many ligands and coordination compounds, ie complexes. It is easy to do, and forms scum (insoluble precipitation, turbidity) derived from a large amount of insoluble calcium.

The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. About too much magnesium (Mg) component, since it will produce an insoluble content, it is preferable that it is 0-70 ppm, and it is especially preferable that it is 0-20 ppm. Metal components such as iron (Fe) content, calcium (Ca) content, and magnesium (Mg) content may be used to pretreat the absolute dry cellulose ester with a micro digest wet decomposition apparatus (components of nitric acid) and alkali melting. It can obtain | require by analyzing using ICP-AES (inductively coupled plasma emission spectroscopy apparatus).

The refractive index of the cellulose ester film used in the present invention is preferably used at 1.45 to 1.60 at 550 nm. The refractive index measurement method of a film is measured based on Japanese Industrial Standard JIS K 7105 using an Abbe refractive index meter.

<Additives>

The cellulose ester film may contain additives such as plasticizers, ultraviolet absorbers, antioxidants, and matting agents.

As described above, the cellulose ester film used for the third protective film according to the present invention preferably has a retardation in the range of 0 to 5 nm and Rt of -10 to 10 nm. In order to make it into the said numerical range, if the 3rd protective film is a cellulose ester, it will manufacture by melt film forming, or it may leave at least 15 second at the temperature of a glass transition point or more in the middle of solution film forming, or the additive which has a birefringence expression opposite to a cellulose ester It is preferable to add. Especially, in order to adjust retardation in the said range, it is preferable to contain the following acrylic polymer.

<Acrylic Polymer>

It is preferable that the cellulose ester film used for the 3rd protective film which concerns on this invention contains the acrylic polymer whose weight average molecular weight which shows negative orientation birefringence with respect to an extending direction is 500 or more and 30000 or less, The said acrylic polymer contains an aromatic ring It is preferable that it is the acrylic polymer which has a side chain, or the acrylic polymer which has a cyclohexyl group.

The polymer has a weight average molecular weight of 500 or more and 30,000 or less, whereby the compatibility of the cellulose ester and the polymer can be improved by controlling the composition of the polymer.

Especially with respect to the acrylic polymer, the acrylic polymer which has an aromatic ring in a side chain, or the acrylic polymer which has a cyclohexyl group in a side chain, if the weight average molecular weight is 500 or more and 10000 or less, In addition to the above, of the cellulose ester film after film forming It is excellent in transparency, and its moisture permeability is also very low, and shows the outstanding performance as a protective film for polarizing plates.

Since the said polymer has a weight average molecular weight of 500 or more and 30000 or less, it is thought that it is between the low molecular weight polymers from an oligomer. In order to synthesize | combine this polymer, in normal superposition | polymerization, control of molecular weight is difficult, It is preferable to use the method which can make molecular weight as uniform as possible by the method which does not increase molecular weight too much.

As such a polymerization method, a method using a peroxide polymerization initiator such as cumene peroxide or t-butylhydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a chain transfer agent such as a mercapto compound or carbon tetrachloride in addition to the polymerization initiator A method of using, a method of using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to a polymerization initiator, and also of a thiol group and a second class such as those disclosed in JP 2000-128911 or 2000-344823 Although the method of block-polymerizing using the compound which has a hydroxyl group, or the polymerization catalyst which used the said compound and organometallic compound together is mentioned, All are used preferably in this invention, Especially the method of the said publication is preferable.

Monomers as monomer units constituting the polymer useful in the present invention are illustrated below, but are not limited thereto.

As an ethylenically unsaturated monomer unit which comprises the polymer obtained by superposing | polymerizing an ethylenically unsaturated monomer: As vinyl ester, For example, vinyl acetate, a vinyl propionate, a vinyl butyrate, a vinyl valerate, a vinyl pivalate, a vinyl caproate, a capric acid Vinyl, vinyl laurate, vinyl myristic acid, vinyl palmitate, vinyl stearate, cyclohexane carboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, cinnamic acid Vinyl and the like; As the acrylic ester, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s- ), Hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i) Cyclohexyl acrylate, acrylic acid (2-ethylhexyl), benzyl acrylate, phenethyl acrylate, acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid ( 3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl and the like; As the methacrylic acid ester, the acrylic acid ester is replaced with a methacrylic acid ester; As unsaturated acid, acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid etc. are mentioned, for example. The polymer composed of the monomer may be a copolymer or a homopolymer, and a homopolymer of vinyl ester, a copolymer of vinyl ester, a copolymer of vinyl ester with acrylic acid or methacrylic acid ester is preferable.

In this invention, an acrylic polymer refers to the homopolymer or copolymer of acrylic acid or methacrylic acid alkylester which does not have a monomeric unit which has an aromatic ring or a cyclohexyl group. The acrylic polymer which has an aromatic ring in a side chain is an acrylic polymer which contains the acrylic acid or methacrylic acid ester monomeric unit which has an aromatic ring by all means.

In addition, the acrylic polymer which has a cyclohexyl group in a side chain is an acrylic polymer containing the acrylic acid or methacrylic acid ester monomeric unit which has a cyclohexyl group.

As an acrylic ester monomer which does not have an aromatic ring and a cyclohexyl group, For example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), acrylic acid Pentyl (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-) ), Myritic acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3 Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid (2-ethoxyethyl), or the like; The thing changed into the acid ester is mentioned.

The acrylic polymer is a homopolymer or a copolymer of the above monomers, but preferably contains 30 mass% or more of acrylic acid methyl ester monomer units, and more preferably 40 mass% or more of methacrylic acid methyl ester monomer units. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

Examples of the acrylic acid or methacrylic acid ester monomer having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl) (O- or m- or p-tolyl), methacrylic acid (o- or m- or p-tolyl (methoxycarbonylphenyl) Benzyl acrylate, benzyl acrylate, benzyl acrylate, phenethyl acrylate, and phenetyl methacrylate are preferable, although benzyl acrylate, benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, phenethyl methacrylate and phenethyl acrylate Can be used.

Among the acrylic polymers having an aromatic ring in the side chain, it is preferable to have 20 to 40 mass% of acrylic acid or methacrylic acid ester monomer units having an aromatic ring and 50 to 80 mass% of acrylic acid or methacrylic acid methyl ester monomer units . It is preferable that the polymer contains 2 to 20 mass% of acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group.

Examples of the acrylic ester monomer having a cyclohexyl group include cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), and acrylic acid (4-ethylcyclohexyl ), Methacrylic acid (4-ethylcyclohexyl) and the like, but cyclohexyl acrylate and cyclohexyl methacrylate can be preferably used.

It is preferable to have 20-40 mass% of acrylic acid or methacrylic acid ester monomeric unit which has a cyclohexyl group in the acrylic polymer which has a cyclohexyl group in a side chain, and also has 50-80 mass%. It is also preferable that the polymer contains 2 to 20% by mass of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group.

A polymer obtained by polymerizing the ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, and an acrylic polymer having a cyclohexyl group in the side chain are all excellent in compatibility with a cellulose resin.

In the case of these acrylic acid or methacrylic acid ester monomers having a hydroxyl group, it is a constituent unit of a copolymer which is not a homopolymer. In this case, It is preferable to contain 2-20 mass% of acrylic acid or methacrylic acid ester monomeric units which have a hydroxyl group preferably.

In the present invention, a polymer having a hydroxyl group in the side chain can also be preferably used. As a monomeric unit which has a hydroxyl group, although it is the same as the above-mentioned monomer, acrylic acid or methacrylic acid ester is preferable, For example, acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxy Propyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, or these acrylic acids as methacrylic acid Substituted things are mentioned, Preferably they are 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The acrylic acid ester or methacrylic acid ester monomer unit having a hydroxyl group in the polymer is preferably contained in the polymer in an amount of 2 to 20 mass%, more preferably 2 to 10 mass%.

The above-mentioned polymer contains not only 2 to 20% by mass of the monomer unit having a hydroxyl group but also excellent compatibility with the cellulose ester, retention property and dimensional stability, and a low moisture permeability, It has an effect that the adhesiveness is particularly excellent and the durability of the polarizing plate is improved.

The method of having a hydroxyl group at at least one end of the main chain of the acrylic polymer is not particularly limited as long as it has a hydroxyl group at the end of the main chain, but a radical polymerization initiator having a hydroxyl group such as azobis (2-hydroxyethylbutyrate) is used. Method, a method of using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method of using a polymerization terminator having a hydroxyl group, a method of having a hydroxyl group at the terminal by living ion polymerization, Japanese Patent Laid-Open No. 2000- It can be obtained by a method of bulk polymerization using a compound having one thiol group and a secondary hydroxyl group as disclosed in 128911 or 2000-344823, or a polymerization catalyst in which the compound and the organometallic compound are used in combination. The method described in the publication is preferred.

The polymer produced by the method according to this publication is commercially available as the Actflow series manufactured by Soken Chemical Co., Ltd., and can be preferably used. The polymer having a hydroxyl group at the terminal and / or the polymer having a hydroxyl group at the side chain have the effect of significantly improving the compatibility and transparency of the polymer in the present invention.

In addition, a polymer using styrene as the ethylenic unsaturated monomer exhibiting negative orientation birefringence with respect to the stretching direction is preferable because it exhibits negative refractivity. Examples of the styrene include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinylbenzoate Ester, and the like, but are not limited thereto.

The unsaturated ethylenic monomer may be copolymerized with an exemplary monomer, and two or more kinds of the above polymers may be used in common in cellulose esters for the purpose of controlling birefringence.

Further, the cellulose ester film used in the present invention has a weight average molecular weight of 5000 obtained by copolymerizing an ethylenically unsaturated monomer Xa which does not have an aromatic ring and a hydrophilic group in a molecule and an ethylenically unsaturated monomer Xb which does not have an aromatic ring in a molecule and has a hydrophilic group. It is preferable to contain the polymer X of 30000 or less and the polymer Y of the weight average molecular weight 500 or more and 3000 or less obtained which superposed | polymerized the ethylenically unsaturated monomer Ya which does not have an aromatic ring more preferably.

<Polymer X, Polymer Y>

Polymer X used in the present invention is a polymer having a weight average molecular weight of 5000 or more and 30000 or less obtained by copolymerizing an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in a molecule and an ethylenically unsaturated monomer Xb having a hydrophilic group without an aromatic ring in a molecule. to be. Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer having no hydrophilic group and no aromatic ring in the molecule.

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

- (Xa) _m - (Xb) _n - (Xc) _p-

More preferably, it is a polymer represented by the following general formula (X1).

-[CH ₂ -C (-R1) (-CO ₂ R2)] _m- [CH ₂ -C (-R3) (-CO ₂ R4-OH)-] _n- [Xc] _p-

(Wherein R 1, R 3 and R 5 represent H or CH ₃ , R ₂ represents an alkyl group having 1 to 12 carbon atoms and a cycloalkyl group, and R 4 and R 6 represent —CH ₂ —, —C ₂ H ₄ — or —C ₃₎ H ₆ −, Xc represents a monomer unit polymerizable to Xa and Xb, and m, n and p represent molar composition ratios, provided that m ≠ 0, n ≠ 0, k ≠ 0, m + n + p = 100)

Although the monomer as a monomer unit which comprises the polymer X used for this invention is illustrated below, it is not limited to this.

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

The ethylenically unsaturated monomer Xa which does not have an aromatic ring and a hydrophilic group in a molecule | numerator is, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), Pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i -), Myritic acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-ethoxyethyl) and the like, or the acrylic acid ester as methacrylic acid ester You can change that. Among them, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate and propyl methacrylate (i-, n-) are preferable.

The ethylenically unsaturated monomer Xb which does not have an aromatic ring in the molecule and has a hydrophilic group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, and examples thereof include acrylic acid (2-hydroxyethyl), acrylic acid Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by substituting acrylic acid with methacrylic acid, preferably acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

Xc is not particularly limited as long as it is an ethylenically unsaturated monomer other than Xa and Xb and copolymerizable therewith, but preferably has no 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. And p in Xc is 0 to 10. Xc may be a plurality of monomer units.

If the molar composition ratio of Xa is large, the compatibility with the cellulose ester will be good, but the retardation value Rt in the film thickness direction will be large. If the molar composition ratio of Xb is large, the compatibility is poor, but the effect of reducing Rt is large. In addition, when the molar composition ratio of Xb exceeds the above range, haze tends to occur at the time of film formation, and it is desirable to optimize these to determine the molar composition ratio of Xa and Xb.

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

By making a weight average molecular weight 5000 or more, the cellulose ester film has a small dimension change under high temperature, high humidity, and since it can obtain the advantage that there is little curling as a polarizing plate protective film, it is preferable. When the weight average molecular weight is set to 30,000 or less, compatibility with the cellulose ester is further improved, bleeding out under high temperature and high humidity, and further, generation of haze immediately after the film formation are suppressed.

The weight average molecular weight of the polymer X used for this invention can be adjusted with a well-known molecular weight adjustment method. As such a molecular weight adjustment method, the method of adding chain transfer agents, such as carbon tetrachloride, lauryl mercaptan, and octyl thioglycolate, etc. are mentioned, for example. The polymerization temperature is usually from room temperature to 130 占 폚, preferably from 50 占 폚 to 100 占 폚, but this can be done by adjusting the temperature or the polymerization reaction time.

The weight average molecular weight can be measured by the following method.

(Method for measuring weight average molecular weight)

The weight average molecular weight Mw is measured using gel permeation chromatography.

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.) were connected and used)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard curve of polystyrene STK Standard polystyrene (manufactured by TOSOH CORPORATION) Calibration curves of 13 samples ranging from Mw = 1000000 to 500 were used. 13 samples are used at almost equal intervals.

Polymer Y used in the present invention is a polymer having a weight average molecular weight of 500 to 3000 obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring.

In the weight average molecular weight 500 or more, the residual monomer of a polymer is reduced and it is preferable. Further, it is preferable to set it to 3000 or less because the retardation value Rt lowering performance is maintained.

Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

Polymer Y used in the present invention is represented by the following formula (Y).

- (Ya) _k - (Yb) _q -

More preferably, it is a polymer represented by following General formula Y1.

-[CH ₂ -C (-R5) (-CO ₂ R6)] _k- [Yb] _q-

(Wherein R5 represents H or CH ₃ , R6 represents an alkyl or cycloalkyl group having 1 to 12 carbon atoms, Yb represents a monomer unit copolymerizable with Ya, and k and q represent a molar composition ratio, but k ≠ 0, k + q = 100)

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Yb may be plural. k + q = 100, and q is preferably 0 to 30.

The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate ( n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n -, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid ( 2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), the acrylic acid as methacrylic acid ester Replacing esters with methacrylic acid esters; Examples of the unsaturated acid include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid, and the like.

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprate, and la. Vinyl urate, vinyl myristic acid, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylic acid, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, and the like are preferable. Yb may be plural.

In order to synthesize | combine the polymers X and Y, it is preferable to adjust the molecular weight in normal superposition | polymerization, and to use the method which can make molecular weight as uniform as possible by the method which does not increase molecular weight too much. As such a polymerization method, a method of using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide, a method of using a polymerization initiator in a larger amount than normal polymerization, a chain transfer agent such as a mercapto compound or carbon tetrachloride in addition to the polymerization initiator Method of using, a method of using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, and further, one thiol group and a secondary class as disclosed in Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. And a method of bulk polymerization using a polymerization catalyst in which the compound having a hydroxyl group or the compound and the organometallic compound are used, and all of them are preferably used in the present invention. The polymerization method which uses the compound which has a hydroxyl group as a chain transfer agent is preferable.

In this case, the ends of the polymer X and the polymer Y have a hydroxyl group and a thioether due to a polymerization catalyst and a chain transfer agent. This terminal residue can adjust the compatibility of the polymers X and Y with the cellulose ester.

The hydroxyl groups of the polymers X and Y are preferably 30 to 150 mgKOH / g.

(Measurement method of hydroxyl value)

This measurement conforms to JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize the acetic acid bound to the hydroxyl group when 1 g of the sample is acetylated. Specifically, sample Xg (about 1 g) is accurately weighed into a flask, and 20 ml of an acetylation reagent (prepared by adding pyridine to 20 ml of acetic anhydride to make 400 ml) is added accurately. The flask inlet is equipped with an air cooling tube and heated in a glycerin bath at 95-100 ° C.

After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from the air cooling tube, and acetic anhydride is decomposed into acetic acid. Next, titration is carried out with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titration apparatus, and the inflection point of the obtained titration curve is set as an end point. Further, as the blank test, the sample is titrated without adding the sample to obtain the inflection point of the titration curve.

The hydroxyl value is calculated by the following formula.

(B-C) x f x 28.05 / X} + D

(Wherein B is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test (ml), C is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the titration (ml), f is 0.5 mol / L) Factor of the potassium hydroxide ethanol solution, D represents the acid value, and 28.05 represents 1/2 of 56.11 of 1 molar amount of potassium hydroxide)

All of the polymer X and the polymer Y described above are excellent in compatibility with the cellulose ester, are excellent in productivity without evaporation or volatilization, have good retention as a protective film for a polarizing plate, have a low moisture permeability and excellent dimensional stability.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = mass of polymer X / mass of cellulose ester 100) and the content of polymer Y is Yg (mass%),

(I) 5? Xg + Yg? 35 (mass%)

(Ii) 0.05? Yg / (Xg + Yg)? 0.4

The preferable range of the formula (i) is 10 to 25 mass%.

When the total amount of the polymer X and the polymer Y is 5% by mass or more, the polymer X and the polymer Y sufficiently function to reduce the retardation value Rt. When the total amount is 35% by mass or less, adhesion with the polarizer PVA is good.

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

<Other additives>

The cellulose ester film which is the protective film of the 1st-4th of this invention can be made to contain the additive which can be added to a normal cellulose ester film.

These additives include plasticizers, ultraviolet absorbers, and fine particles.

It is preferable to contain the following plasticizers in this invention. Examples of the plasticizer include phosphate ester plasticizers, phthalic ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, glycolate plasticizers, citric acid ester plasticizers, polyester plasticizers, polyhydric alcohol ester plasticizers, and the like. Can be preferably used.

Phosphoric acid ester plasticizers include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate and tributyl phosphate. In the trimellitic acid plasticizers such as ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate and dicyclohexyl phthalate, tributyl trimellitate and triphenyl In the pyromellitic acid ester plasticizer, such as trimellitate and triethyl trimellitate, tetrabutyl pyromellitate, tetraphenyl pyromellitate, tetraethyl pyromellitate, and the like, and in the glycolate plasticizer, triacetin, tributylin, ethyl Phthalylethyl In citric acid ester plasticizers, such as a glycolate, methyl phthalyl ethyl glycolate, and butyl phthalyl butyl glycolate, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, and acetyl tri-n-butyl citrate , Acetyltri-n- (2-ethylhexyl) citrate and the like can be preferably used. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, various trimellitic acid esters.

As the polyester plasticizers, copolymerized polymers of dibasic acids and glycols such as aliphatic dibasic acids, alicyclic dibasic acids, and aromatic dibasic acids can be used. The aliphatic dibasic acids are not particularly limited, but adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid and the like can be used. As the glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol and 1,2- . These dibasic acids and glycols may be used alone, or may be used by mixing two or more kinds.

The polyhydric alcohol ester plasticizer includes an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid. As an example of a preferable polyhydric alcohol, although the following is mentioned, for example, this invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, 2-n-butyl -2-ethyl-1,3-propanediol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, etc. Can be mentioned. In particular, it is preferable that they are triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylol propane, and xylitol. There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. When alicyclic monocarboxylic acid and aromatic monocarboxylic acid are used, it is preferable at the point which improves moisture permeability and retention. Although the following are mentioned as an example of a preferable monocarboxylic acid, This invention is not limited to these. As the aliphatic monocarboxylic acid, a linear or branched chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably from 1 to 20 carbon atoms, and particularly preferably from 1 to 10 carbon atoms. The addition of acetic acid increases the compatibility with the cellulose ester, and therefore, it is also preferable to use a mixture of acetic acid and other monocarboxylic acids. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecyl acid, lauric acid, Tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachinic acid, behenic acid, lignoseric acid, sertric acid, heptaconic acid, montanic acid, meli And unsaturated fatty acids such as saturated fatty acids such as succinic acid and lacseric acid, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, or derivatives thereof. As an example of a preferable aromatic monocarboxylic acid, the thing which introduce | transduced the alkyl group into the benzene ring of benzoic acid, such as benzoic acid and toluic acid, and two benzene rings, such as biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, The aromatic monocarboxylic acid which has the above, or derivatives thereof are mentioned. Particularly preferred is benzoic acid. Although the molecular weight of a polyhydric alcohol ester does not have a restriction | limiting in particular, It is preferable that it is the range of the molecular weight 300-1500, and it is more preferable that it is the range of 350-750. The larger one is preferable at the point of retention retention, and the smaller one is preferable at the point of moisture permeability and compatibility with a cellulose ester.

The carboxylic acid used for the polyhydric alcohol ester used for this invention may be 1 type, or 2 or more types may be mixed. In addition, all the OH groups in the polyhydric alcohol may be esterified with carboxylic acid, or some may be left as OH groups.

It is preferable to use these plasticizers individually or in combination.

As for the usage-amount of these plasticizers, 1-20 mass% is preferable with respect to a cellulose ester from a film performance, processability, etc., Especially preferably, it is 3-13 mass%.

The ultraviolet absorber which can be used for this invention aims at improving durability by absorbing the ultraviolet-ray below 400 nm, Especially, it is preferable that the transmittance | permeability in wavelength 370nm is 10% or less, More preferably, it is 5% or less More preferably, it is 2% or less.

Although the ultraviolet absorber used for this invention is not specifically limited, For example, an oxybenzophenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone type compound, a cyanoacrylate type compound, a triazine type compound, nickel complex salt A system compound, an inorganic powder, etc. are mentioned. It can also be set as a polymer type ultraviolet absorber.

It is preferable to use microparticles | fine-particles for the cellulose ester film used for this invention. The fine particles may be either an inorganic compound or an organic compound. Examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, calcium hydrate silicate, aluminum silicate, magnesium silicate and calcium phosphate. . It is preferable that microparticles | fine-particles contain silicon from the point which becomes turbidity low, and silicon dioxide is especially preferable.

The average particle diameter of the primary particles of the fine particles is preferably from 5 to 50 nm, more preferably from 7 to 20 nm. These are preferably contained mainly as secondary agglomerates having a particle size of 0.05 to 0.3 탆. The content of these fine particles in the cellulose ester film is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.5% by mass. In the case of a multi-layered cellulose ester film by a covalent method, it is preferable that the surface contains fine particles in the added amount.

The fine particles of silicon dioxide are commercially available, for example, under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.) , Can be used.

The fine particles of zirconium oxide are commercially available, for example, under the trade names AEROSIL R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the polymer include a silicone resin, a fluororesin, and an acrylic resin. Silicone resin is preferable and it is preferable to have a three-dimensional network structure especially, for example, Tospal 103, 105, 108, 120, 145, 3120, and 240 (above manufactured by Toshiba Silicone Co., Ltd.) It is marketed under the brand name of, and can be used.

Among them, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a high effect of lowering the friction coefficient while keeping the turbidity of the cellulose ester film low.

<Method for producing cellulose ester film>

Next, the manufacturing method of the cellulose ester film used for this invention is demonstrated.

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

The manufacture of the cellulose ester film used for this invention is a process of manufacturing a dope by dissolving a cellulose ester and an additive in a solvent, the process of cast | flow_spreading on the endless metal support body which infinitely shifts a dope, and the process of drying flexible dope as a web. , The step of peeling from the metal support, the step of stretching or maintaining the width, the step of further drying, and the step of winding up the finished film.

The process for producing the dope will be described. The concentration of the cellulose ester in the dope is preferable because the darker one can reduce the dry load after being soft to the metal support, but if the concentration of the cellulose ester is too high, the load during filtration increases and the filtration accuracy becomes worse. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

The solvent to be used in the dope may be used alone or in combination of two or more kinds. However, it is preferable from the viewpoint of production efficiency to use a mixture of a cellulose ester ester and a poor solvent in view of the productivity. In view of solubility of the cellulose ester desirable.

A preferable range of the mixing ratio of the both agent and the poor solvent is 70 to 98% by mass of both the solvent and 2 to 30% by mass of the solvent. As for the two-solvent and the low-solvent, the two solvents in which the cellulose ester to be used is dissolved solely are defined as a poor solvent, and those that are not swollen or dissolved solely are defined as poor solvents.

For this reason, depending on the average degree of acetylation (acetyl group substitution degree) of a cellulose ester, a good solvent and a poor solvent change, for example, when using acetone as a solvent, the acetate ester of a cellulose ester (acetyl group substitution degree 2.4), cellulose In acetate propionate, it becomes a good solvent, and in an acetate ester of cellulose (acetyl group substitution degree 2.8), it becomes a poor solvent.

Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as methylene chloride, dioxolane, acetone, methyl acetate, acetoacetate, etc. are mentioned. Particularly preferred are methylene chloride or methyl acetate.

In addition, the poor solvent used for this invention is although it does not specifically limit, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. It is preferable that the dope contains 0.01 to 2% by mass of water. Further, the solvent used for dissolving the cellulose ester is recovered from the film by drying in the film-forming step, and is used by reusing the solvent.

As a method for dissolving cellulose ester in producing the above-described dope, a general method can be used. When heating and pressurization are combined, heating can be performed at a boiling point or more at normal pressure. It is preferable to stir and dissolve the solvent while heating at a temperature in the range where the solvent is not boiled under pressure while the boiling point of the solvent is equal to or higher than the boiling point at the normal pressure to prevent the generation of massive solids called gels or agglomerates. It is also preferable to use a method in which the cellulose ester is mixed with a poor solvent to wet or swell the cellulose ester, followed by further adding a two-component agent to dissolve the cellulose ester.

The pressurization can be performed by a method of injecting an inert gas such as nitrogen gas or a method of raising the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, and for example, a jacket type is preferable because the temperature can be easily controlled.

The higher the heating temperature after the addition of the solvent is, the more favorable from the viewpoint of the solubility of the cellulose ester. However, if the heating temperature is too high, the required pressure becomes large and the productivity becomes poor. The heating temperature is preferably 45 to 120 占 폚, more preferably 60 to 110 占 폚, and even more preferably 70 to 105 占 폚. The pressure is also adjusted so that the solvent does not boil at the set temperature.

In addition, a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

Next, this cellulose ester solution is filtered using a suitable filter medium such as a filter paper. As a filter medium, although absolute filtration precision is smaller in order to remove an insoluble matter etc., there exists a problem that clogging of a filter medium is easy to produce when absolute filtration precision is too small. Therefore, a filter material having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter material of 0.001 to 0.008 mm is more preferable, and a filter material of 0.003 to 0.006 mm is more preferable.

The material of the filter medium is not particularly limited and a usual filter material can be used. However, a plastic filter material such as polypropylene or Teflon (registered trademark) or a metal filter material such as stainless steel is preferable because the fibers do not fall off. It is preferable to remove and reduce the impurities contained in the cellulose ester which is a raw material, especially a bright point foreign matter by filtration.

The spots foreign material is a substance in which two polarizing plates are placed in a crossed Nicols state and a roll of cellulose ester is placed therebetween and light is irradiated from the side of one polarizing plate and light from the opposite side leaks when observed from the side of the other polarizing plate (Foreign matter) visible to the user, and it is preferable that the number of wigs having a diameter of 0.01 mm or more is 200 pieces / cm ² or less. More preferably, it is 100 pieces / cm <^2> or less, More preferably, it is 50 pieces / m <^2> or less, More preferably, it is 0-10 pieces / cm <^2> or less. It is also preferable that the luminescent viscosity is 0.01 mm or less.

The dope can be filtered by a conventional method, but the method of filtration while heating at a temperature in a range where the boiling point at the normal pressure of the solvent is higher than the boiling point under pressure and the solvent is different from the filtration pressure before and after filtration (called a differential pressure) The rise of is small and preferable. Preferable temperature is 45-120 degreeC, 45-70 degreeC is more preferable, and it is still more preferable that it is 45-55 degreeC.

The filtration pressure is preferably small. 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.

Here, the softness of the dope will be described.

The metal support in the casting (casting) step is preferably a mirror-finished surface, and as the metal support, a stainless steel belt or a drum plated with a casting is preferably used. The width of the casting can be 1 to 4 m. The surface temperature of the metal support of the casting process is preferably at a temperature below -50 ° C to a boiling point of the solvent, because a higher temperature can speed up the drying speed of the web, but if it is too high, the web foams and the planarity is degraded. have. The preferred support temperature is 0 to 40 占 폚, more preferably 5 to 30 占 폚.

Or it is also a preferable method to gelatinize a web by cooling and peeling from a drum in the state containing many residual solvents.

The method of controlling the temperature of the metal support is not particularly limited, but there is a method of spraying hot air or cold air, or a method of bringing hot water into contact with the back surface of a metal support. The use of hot water is preferable because the heat transfer is performed efficiently and the time until the temperature of the metal support becomes constant is short. When using warm air, the wind of temperature higher than the target temperature may be used.

In order for the film-like cellulose ester to exhibit good planarity, the residual solvent amount at the time of peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

In the drying step of the film-like cellulose ester, the web is peeled off from the metal support and further dried to make the residual solvent amount 1 mass% or less, more preferably 0.1 mass% or less, particularly preferably. It is 0-0.01 mass% or less.

In the film drying process, generally, a roll drying method (a method of drying a plurality of rolls disposed at upper and lower sides by alternately passing webs) or a method of drying while conveying the web by a tenter method is employed.

In order to manufacture the cellulose-ester film used for the 2nd protective film which concerns on this invention, it extends to a conveyance direction (= long direction) by the web immediately after peeling from a metal support body, where the amount of residual solvent is large, and also of a web It is preferable to extend | stretch in the width direction by the tenter system which grasps both ends by a clip etc.

Stretching operation may be performed by dividing into multiple layers, and it is preferable to perform biaxial stretching in the casting direction and the width direction. In addition, simultaneous biaxial stretching may be performed in the case of biaxial stretching, or it may be carried out stepwise. In this case, with a step, it is also possible, for example, to perform extending | stretching which differs in extending directions, can divide extending | stretching of the same direction into multiple layers, and can also apply extending | stretching of another direction to any one of them. Do.

The preferred draw ratio is 1.05 to 2 times, preferably 1.1 to 1.5 times. It can shrink | contract longitudinally at the time of simultaneous biaxial stretching, and can shrink | contract so that it may be 0.8-0.99, Preferably it is 0.9-0.99. Preferably, the area is preferably 1.12 times to 1.44 times, and preferably 1.15 times to 1.32 times by transverse stretching and longitudinal stretching or shrinkage. This can be calculated | required by the draw ratio of a longitudinal direction x draw ratio of a horizontal direction.

In addition, the "stretching direction" in the present invention is usually used in the sense of a direction in which a stretching stress is applied directly in the case of performing a stretching operation, but in the case of biaxial stretching in a multi-layered layer, the stretching ratio is finally increased. It may also be used in the sense of the side (ie, the direction which is usually the slow axis).

In the cellulose ester film used for the second protective film according to the present invention, the retardation represented by the following formulas (3) and (4) is in the range of 30 to 115 nm of Ro and 100 to 250 nm of Rt, and Rt / Ro is In the range 1.6 to 4.4. In addition, Ro is in the range of 45 to 95 nm, Rt is in the range of 110 to 200 nm, and Rt / Ro is preferably in the range of 2.0 to 3.5. In addition, retardation is measured at wavelength 590nm in the environment of 23 degreeC and 55% RH.

In particular, in the range of about 1.1 to 1.5 times orthogonal to a conveyance direction in the range of about a glass transition point +/- 10 degreeC, or the film manufactured by the solution casting | flow_spread, the amount of residual solvents remaining about 2-100 mass%, By extending | stretching about 1.1 to 1.7 times in the direction orthogonal to a conveyance direction, it can be included in the said retardation range.

In addition, the retardation of the state which laminated | stacked the 2nd protective film and retardation layer which concerns on this invention has Ro of 30-105 nm and Rt of -300-25 nm. Moreover, Ro is 45-95 nm, Rt is -100-25 nm, Especially preferably, Rt is the range of -60-20 nm.

Moreover, in the state which laminated | stacked the 2nd protective film which concerns on this invention, and the retardation layer, the said laminated | multilayer film has an optical axis in the same surface, and the wavelength dispersion characteristic defined by following formula (5), (6), (8) is

D (Ro) 1: 0.9 to 1.0

D (Ro) 2: -9.5 to 0 nm

D (Rt) 1: 0.3 to 0.9

D (Rt) 2: -100 to -10 nm

The absolute value of the angle formed by the transmission axis of the first polarizing film and the in-plane slow axis of the second protective film is in the range of 0 to 1 °.

In particular, D (Ro) 1 is preferably in the range of 0.93 to 0.98, and D (Rt) 1 is preferably 0.4 to 0.8, and preferably in the range of 0.45 to 0.65.

In order to make the absolute value of the angle formed between the transmission axis of the first polarizing film and the in-plane slow axis of the second protective film in the range of 0 to 1 °, the in-plane slow axis of the second protective film is made orthogonal to the conveying direction. This can be achieved by controlling in-plane nonuniformity. For this purpose, it is preferable to precisely control the balance of the stretching temperature and the stretching ratio, and to control the stretching portion (clip of tenter, etc.) independently on both sides of this protective film. This can be achieved by adjusting the stretching temperature and the stretching magnification with respect to the clip position and the stress of the clip.

&Quot; (3) &quot;

Ro = (nx-ny) xd

&Quot; (4) &quot;

Rt = ((nx + ny) / 2-nz) × d

(Wherein the refractive index of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer is in the slow axis direction in the plane of nx, and the refractive index in the direction orthogonal to the slow axis in the plane is ny, in the thickness direction Refractive index nz and d represent the respective thickness (nm))

&Quot; (5) &quot;

D (Ro) 1 = Ro (630) / Ro (480)

&Quot; (6) &quot;

D (Ro) 2 = Ro (630) -Ro (480)

&Quot; (7) &quot;

D (Rt) 1 = | Rt (630) / Rt (480) │

&Quot; (8) &quot;

D (Rt) 2 = Rt (480) -Rt (630)

(In formula, Ro (480), Ro (630) are the retardation Ro values at 480 nm and 630 nm, respectively, at 23 degreeC and 55% RH, and Rt (480), Rt (630) are respectively 480nm, Retardation Rt value at 630 nm)

As means for controlling the wavelength dispersion, D (Ro) 1 and D (Ro) 2 can achieve appropriate selection of a material and a manufacturing method of the second protective film. Regarding the material, it is preferable to change the substituent (type and degree of substitution) with a cellulose ester-based material. In the case of only the acetyl group, the lower the degree of substitution, the larger the value, and the larger the propionyl group, the smaller the tendency. Moreover, it changes also with an additive. Generally, in the case of a retardation increasing agent, it tends to become large. It is preferable that D (Rt) 1 and D (Rt) 2 control each phase difference between the second passivation film and the retardation layer. Specifically, it becomes a small value by making the phase difference of a 2nd protective film relatively large.

Retardation of the said 1st protective film and the 4th protective film used for the polarizing plate of this invention is not specifically limited, As retardation Ro of in-plane direction, the range of 30 nm-1000 nm is preferable, More preferably, 30 It is the range of nm-500 nm, Especially preferably, it is 30 nm-150 nm, Most preferably, it is the range of 30 nm-75 nm.

Moreover, as retardation Rt of thickness direction, the range of 30 nm-1000 nm is preferable, More preferably, it is the range of 30 nm-500 nm, Especially preferably, it is the range of 30 nm-250 nm.

It is preferable that the film thickness of the cellulose-ester film used for the 1st-4th protective film which concerns on this invention is 20-200 micrometers, It is more preferable that it is 20-100 micrometers, It is more preferable that it is 20-80 micrometers desirable. In particular, it is preferable that the cellulose-ester film used for a 3rd protective film is 20-45 micrometers in order to acquire the effect of this invention.

(Polarizer)

A polarizing plate can be manufactured by a general method. Alkaline saponification of the back surface side of the cellulose ester film used for the 1st-4th protective film of this invention, the immersion extending | stretching in iodine solution, and using at least one surface of the polarizing film manufactured using the fully saponified polyvinyl alcohol aqueous solution It is preferable to bond. The said film may be used for the other side, and another polarizing plate protective film may be used. Commercially available cellulose ester films (for example, Konica Minolta Tag KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR (manufactured by Konica Minolta Opto Co., Ltd.) are also preferably used).

The polarizing film, which is a main component of the polarizing plate, is a device which allows only light of a polarization plane in a certain direction to pass through. A representative polarizing film currently known is a polyvinyl alcohol-based polarizing film, which is dyed with iodine on a polyvinyl alcohol-based film. Some dyes are colored. The polarizing film is formed by forming a polyvinyl alcohol aqueous solution, uniaxially stretching the dye, or dyeing after dyeing, and then performing a durable treatment with a boron compound.

(Display device)

By assembling the polarizing plate of the present invention into a liquid crystal display device, the liquid crystal display device of the present invention excellent in visibility can be manufactured. Although the polarizing plate of this invention is used suitably in IPS mode type | mold LCD, it is especially used for the IPS mode type | mold liquid crystal display which employ | adopted the structure prescribed | regulated in Claim 5 or Claim 6. In particular, even if the screen is a liquid crystal display device having a large screen of 30 or more types, in particular, 30 to 54 types, the contrast is high, and in particular, there is an effect that eyes are not tired even with long-term viewing by suppressing color change caused by vision.

Although an Example is given to the following and this invention is concretely demonstrated to it, this invention is not limited to these.

Example 1

<< retardation and measurement of wavelength dispersion >>

In the Example, retardation measurement was performed in the environment of 23 degreeC and 55% RH using KOBRA 21ADH made from Oji Keisoku Kiki. In addition, when calculating the retardation of the thickness direction, the value which measured the refractive index of the said wavelength of each layer using the Abbe refractometer was used. In the case of a laminated body, the average value of the refractive index of each layer was used. The following equation (3) and (4) were used to calculate the retardation.

Samples in which the retardation in the thickness direction of the laminate in the present invention has a negative value are calculated by measuring the retardation when the in-plane fastening axis of the laminate is inclined and 40 degrees inclined when calculating the retardation. It was used for.

&Quot; (3) &quot;

Ro = (nx-ny) xd

&Quot; (4) &quot;

Rt = ((nx + ny) / 2-nz) × d

(Wherein the refractive index of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer is in the slow axis direction in the plane of nx, and the refractive index in the direction orthogonal to the slow axis in the plane is ny, in the thickness direction Refractive index nz and d represent the respective thickness (nm))

In addition, the wavelength dispersion characteristic was calculated according to the equations (5) to (8).

&Quot; (5) &quot;

D (Ro) 1 = Ro (630) / Ro (480)

&Quot; (6) &quot;

D (Ro) 2 = Ro (630) -Ro (480)

&Quot; (7) &quot;

D (Rt) 1 = | Rt (630) / Rt (480) │

&Quot; (8) &quot;

D (Rt) 2 = Rt (480) -Rt (630)

(In formula, Ro (480), Ro (630) are the retardation Ro values at 480 nm and 630 nm, respectively, at 23 degreeC and 55% RH, and Rt (480), Rt (630) are respectively 480nm, Retardation Rt value at 630 nm)

<< Production of protective films A-L having a phase difference layer >>

(Silicon dioxide dispersion)

12 parts by mass of aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.)

(Average diameter 16 nm, apparent specific gravity 90 g / liter of primary particles)

Ethanol 88 parts by mass

The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with a Manton-Gaulin disperser. The turbidity of the liquid after dispersion was 200 ppm. 88 mass parts of methylene chloride was thrown into the silicon dioxide dispersion with stirring, and it stirred and mixed for 30 minutes with the dissolver, and prepared the silicon dioxide dispersion dilution liquid.

(Dope)

100 mass parts of cellulose esters (acetyl group substitution degree 2.50, propionyl group substitution degree 0.10, total acyl group substitution degree 2.60)

5 parts by mass of trimethylolpropane tribenzoate

5 parts by mass of ethyl phthalyl ethyl glycolate

10 parts by mass of silicon dioxide dispersion diluent

Tinuvin 109 (Shiba Specialty Chemicals Co., Ltd.) 1.2 parts by mass

Tinuvin 171 (Shiba Specialty Chemicals Co., Ltd.) 0.8 parts by mass

Methylene chloride 430 parts by mass

40 parts by mass of ethanol

The said dope composition was put into the sealing container, it heated to 70 degreeC, the cellulose ester was melt | dissolved completely, stirring, and the dope liquid was obtained. Next, after filtering a dope liquid, the dope liquid adjusted to temperature at 33 degreeC was sent to the die, and it was uniformly cast by the width 2.5m on the stainless steel belt from the die slit. The flexible part of the stainless belt was heated with warm water at 37 ° C from the rear surface. After casting, the dope film on the metal support (called a web after being cast on a stainless belt) was dried by heating at 44 ° C., and the residual solvent amount of the peeling was peeled off at 120 mass%, and the tension at the time of peeling was increased to 1.1 times. It extended | stretched so that it might become a longitudinal stretch ratio, and then hold | maintained the web edge part with the tenter at the residual solvent amount 24% and temperature 135 degreeC, and it extended | stretched so that it might become 1.2 times the draw ratio in the width direction. After extending | stretching, after hold | maintaining for several seconds, maintaining the width | variety, the tension | tensile_strength of the width direction was alleviated, and it dried at 120 degreeC after releasing width maintenance. The cellulose ester film of 30 micrometers of thickness, 2.65 m in width, and 7500 m in length produced as mentioned above was wound up to the core.

As for the phase difference of this cellulose-ester film, Ro was 30 nm, Rt was 130 nm, and Rt / Ro was 4.3.

Next, the following retardation layer was provided on the obtained cellulose ester film.

45 mass% of the compounds of the formula (a)

45 mass% of the compounds of the formula (b)

10% by mass of the compound of formula (d)

A polymerizable liquid crystal composition (H) containing was prepared. The nematic-isotropic liquid phase transition temperature of this polymeric liquid crystal composition (H) was 73 degreeC. Polymeric liquid crystal composition (H1) which added 0.1% of photopolymerization initiator Lucirin TPO (made by BASF Corporation) and 0.1% of hindered amine LS-765 (made by Sankyo Life Tech Co., Ltd.) to 99.7% of polymeric liquid crystal compositions (H). Was prepared. Next, xylene solution containing 33% of the polymerizable liquid crystal composition (H1) was prepared. This xylene solution was applied on the cellulose ester film by a die coater to a thickness of 5 탆. The coated film was irradiated with ultraviolet rays of 250 mJ / mm at a concentration of 0.2% and a temperature of 38 ° C. for 80 seconds to cure the polymerizable liquid crystal composition (H1) to obtain a protective film A having a retardation layer.

When the phase difference of this cured film was measured, Ro was 0.5 nm, Rt was -288 nm, and Ro of the protective film A which has a laminated phase difference layer was 30.5 nm, and Rt was -105 nm.

In addition, D (Ro) 1 defined by the above formula was 0.9, D (Ro) 2 was -3.09 nm, D (Rt) 1 was 0.70, and D (Rt) 2 was -36 nm.

Then, as a 2nd protective film, the cellulose ester of the kind of Table 1, Table 2, the extending | stretching conditions and film thickness of Table 3, and the composition ratio of the compound represented by General formula (a), (b), (d) The protective films B to L having the retardation layers were manufactured in the same manner as in the preparation of the protective film A having the retardation layer, except that the retardation layers shown in Table 1 and Table 2 were used.

<< Manufacture of protective films M and N which have a phase difference layer >>

As the cellulose ester, except for using cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.75), protective films M and N having a phase difference layer were prepared in the same manner as the protective film A having a phase difference layer.

<< Manufacture of protective films O and P which have a phase difference layer >>

The cellulose ester film which is a 2nd protective film was manufactured as follows.

(Preparation of Dope Liquid B)

Cellulose ester (cellulose triacetate synthesized from linter)

                                           100 parts by mass

(Mn = 148000, Mw = 310000, Mw / Mn = 2.1)

9.5 parts by mass of triphenylphosphate

Ethylphthalyl ethyl glycolate 2.2 parts by mass

440 parts by mass of methylene chloride

40 parts by mass of ethanol

The above was put into an airtight container, heated, dissolved completely while stirring, and filtered using Azumi filter paper No. 24 manufactured by Azumi Rossi Co., Ltd., to prepare a dope liquid B. The dope liquid B was filtered with the fine met NF of Nippon Seisen Co., Ltd. in the film forming line (a part of dope liquid B was used also for manufacture of the following inline addition liquid B).

(Silicon Dioxide Dispersion B)

Aerosol 200V (Nippon Aerosil Co., Ltd.) 2 parts by mass

(Average diameter 12nm of primary particle, apparent specific gravity 100 g / liter)

18 parts by mass of ethanol

The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with a manton-gaulin disperser. The turbidity of the liquid after dispersion was 100 ppm. 18 mass parts of methylene chloride was thrown into the silicon dioxide dispersion with stirring, and it stirred and mixed for 30 minutes with the dissolver, and prepared the silicon dioxide dispersion dilution B.

(Manufacture of inline addition liquid B)

100 parts by mass of methylene chloride

Dope liquid B 34 parts by mass

Tinuvin 109 (Shiba Specialty Chemicals, Inc.) 5 parts by mass

5 parts by mass of Tinuvin 171 (manufactured by Ciba Specialty Chemicals)

Tinuvin 326 (Shiba Specialty Chemicals, Inc.) 3 parts by mass

The above was put into a sealed container, heated, dissolved completely while stirring, and filtered.

20 mass parts of silicon dioxide dispersion dilution liquid B was added to this, stirring, and after stirring for 60 minutes, it filtered with the polypropylene wind cartridge filter TCW-PPS-1N of Advantech Toyo Co., Ltd., and the inline addition liquid B was manufactured. It was.

In the line of in-line addition liquid, the in-line addition liquid B was filtered by Nippon Seisen Co., Ltd. FineMet NF. 2.5 parts by mass of the filtered in-line addition liquid B was added to 100 parts by mass of the filtered dope liquid B, and the mixture was sufficiently mixed with an in-line mixer (Toray static tube mixer Hi-Mixer, SWJ), followed by temperature using a belt casting device. ℃, 2.5 m in width was uniformly cast on a stainless band support. In the stainless band support, the solvent was evaporated until the amount of residual solvent became 100% and peeled off on the stainless band support. The solvent was evaporated at 35 degreeC on the web of the peeled cellulose ester, and it dried at 130 degreeC drying temperature, extending | stretching 1.2 times in the width direction with a tenter after that. At this time, the amount of residual solvent when extending | stretching was started with a tenter was 11%. Thereafter, drying was terminated while conveying the drying zone at 120 ° C. and 110 ° C. with a large number of rolls, slitted at a width of 2.6 m, and a knurling process having a width of 15 mm and an average height of 10 μm was applied to both ends of the film, and the winding initial tension was obtained. A cellulose ester film O as a second protective film having a film thickness of 80 µm and a length of 7500 m was prepared by winding the core 6 inches at 220 N / m and a final tension of 110 N / m.

In the same manner, a cellulose ester film P as a second protective film having a thickness of 40 µm and a length of 7500 m was produced without stretching in the width direction.

Next, using the produced cellulose ester films O and P, the protective films O and P having the retardation layer were manufactured in the same manner as the protective film A having the retardation layer.

<< Production of protective film Q (and third protective films Q, V to Z) having a phase difference layer >>

&Lt; Synthesis of Polymer &

(Synthesis of polymer X)

Polymer X was synthesized with reference to the method described in Japanese Patent Laid-Open No. 2003-12859. That is, the monomer which mixed methyl methacrylate (MMA): 2-hydroxyethyl methacrylate (HEMA) in the ratio of 80:20 to the glass flask with a stirrer, two dripping funnels, a gas introduction tube, and a thermometer. 40 g of the liquid mixture, 3.0 g of mercaptopropionic acid of a chain transfer agent, and 30 g of toluene were thrown in, and it heated up at 90 degreeC. Thereafter, 60 g of the monomer mixture was dropped over 3 hours from one dropping funnel, and 0.6 g of azobisisobutyronitrile dissolved in 14 g of toluene was simultaneously added dropwise over 3 hours from the other funnel. . Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was further added dropwise over 2 hours, and then the reaction was continued for another 2 hours to obtain polymer X. The weight average molecular weight was 8000.

(Synthesis of polymer Y)

Bulk polymerization was carried out by the polymerization method described in Japanese Patent Laid-Open No. 2000-344823. That is, the contents were heated to 70 占 폚 while introducing methylmethacrylate and ruthenocene into a flask equipped with a stirrer, a nitrogen gas introducing tube, a thermometer, an inlet and a reflux condenser. Subsequently, half of the following β-mercaptopropionic acid, which was sufficiently nitrogen-substituted, was added into the flask under stirring. After the addition of? -mercaptopropionic acid, the content in the flask during stirring was kept at 70 占 폚 and polymerization was carried out for 2 hours. Furthermore, after adding the other half of the nitrogen gas-substituted (beta) -mercaptopropionic acid further, superposition | polymerization was performed for 4 hours, maintaining the temperature of the content in stirring at 70 degreeC. The temperature of the reaction was returned to room temperature, and 20 mass parts of a tetrahydrofuran solution of 5 mass% benzoquinone was added to the reaction to terminate the polymerization. Tetrahydrofuran, the remaining monomers and the remaining thiol compound were removed while the polymer was slowly heated to 80 ° C. under reduced pressure with an evaporator to obtain polymer Y. The weight average molecular weight was 1,000.

100 parts by mass of methyl methacrylate

Luthenocene (metal catalyst) 0.05 parts by mass

12 parts by mass of β-mercaptopropionic acid

The measuring method of a weight average molecular weight is shown below.

(Method for measuring weight average molecular weight)

The weight average molecular weight Mw was measured by gel permeation chromatography.

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.) were connected and used)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration Curve: Standard Polystyrene STK Standard Polystyrene (manufactured by Tosoh Corporation) Mw = 1000000 to 500, a calibration curve with 13 samples was used. Thirteen samples were used at approximately equal intervals.

Using the said polymer X, Y, the protective film Q which has a retardation layer and the 3rd protective films Q, V to Z which do not provide a retardation layer were manufactured as shown below.

(Dope)

Cellulose triacetate

(Acetization degree: 61.5%, Mn: 110000, Mw / Mn = 2.0) 100 parts by mass

10 parts by mass of polymer

Polymer Y 5 parts by mass

Methylene chloride 430 parts by mass

40 parts by mass of ethanol

The said dope composition was put into the sealing container, it heated to 70 degreeC, the cellulose triacetate (TAC) was dissolved completely, stirring, and dope was obtained. The time required for dissolution was 4 hours. Next, after filtering a dope composition, the cellulose-ester solution temperature-controlled at 33 degreeC was sent to the die, and it casted uniformly in width 2.5m on the stainless belt from the die. The flexible part of the stainless belt was heated with warm water at 37 ° C from the rear surface. After softening, the dope film on the metal support (called a web after being flexible to the stainless belt) was dried by heating at 44 ° C in warm air, the residual solvent amount of the peeling was peeled off at 120 mass%, and the tension at the time of peeling was increased to 1.1 times. It extended | stretched so that it might become a longitudinal stretch ratio, it adjusted so that it might become 4 mass% of residual solvent amount, and temperature 123 degreeC, the web edge part was hold | maintained with the tenter, and it extended | stretched so that it might become 1.1 times the draw ratio in the width direction. After extending | stretching, after hold | maintaining for several seconds, maintaining the width | variety, after tension | tensile_strength of the width direction was relieved, width | variety maintenance was released and it dried at 120 degreeC. The cellulose-ester film which is the 2nd protective film of 41 micrometers of thickness, 2.65 m in width, and 7500 m in length produced as mentioned above was wound up to the core.

Next, in the same manner as the protective film A having the retardation layer, a retardation layer was provided to prepare a protective film Q having the retardation layer.

In addition, the said cellulose ester film was used as 3rd protective film Q without providing a retardation layer. As for the retardation of the 3rd protective film Q, Ro was 0.8 nm and Rt was 1 nm.

In addition, the ratio of the polymer X and the polymer Y was changed, and the 3rd protective films V-Z which have retardation and film thickness of Table 1 and Table 2 were manufactured.

<< Production of protective films R to U having a phase difference layer >>

Except having changed the substitution degree of a cellulose ester as it described in Table 1, it carried out similarly to manufacture of the protective film A which has a retardation layer, and produced the protective films R-U with retardation layer.

As described above, the protective films A to U having the retardation layer and the third protective films Q and V to Z having no retardation layer were prepared.

<< Production of Polarizer >>

The protective films A to U having the above-mentioned retardation layer and the third protective films Q and V to Z without providing the retardation layer were alkali treated with a 2.5 mol / L sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, and washed with water for 3 minutes. Saponification treatment gave an alkali treatment film.

Next, the polyvinyl alcohol film of thickness 120micrometer was uniaxially stretched (temperature 110 degreeC, draw ratio 5 times). This was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, followed by immersion in an aqueous solution at 68 ° C. containing 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. This was washed with water and dried to obtain a polarizing film.

Next, the polarizing film prepared above and Konica Minolta Tag, which is a commercially available polarizing plate protective film, and KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) were saponified by the above method, and a fully saponified polyvinyl alcohol 5% aqueous solution was used as an adhesive. , Protective films A to U having a retardation layer, polarizing films, and KC4UY (first protective film) were laminated in this order to produce a viewing polarizing plate. In the same manner, the third protective films Q, V to Z, the polarizing film, and the KC4UY (fourth protective film) without the retardation layer were laminated in this order to manufacture a polarizing plate on the backlight side (BL side).

<< Manufacturing of Liquid Crystal Display Device >>

A liquid crystal panel for performing the viewing angle measurement was manufactured as follows, and the characteristics as a liquid crystal display device were evaluated.

The previously bonded polarizing plate of the liquid crystal television Wooo W17-LC50 manufactured by Hitachi, which is an IPS mode type liquid crystal display device, was peeled off, and the manufactured viewing side and the BL side polarizing plate were bonded to the glass surface of the liquid crystal cell with the configuration of FIG. The mode type liquid crystal display devices 1-26 were manufactured. The in-plane slow axis of the second protective film of the polarizing plate and the alignment direction of the liquid crystal cell were substantially parallel.

<< evaluation of liquid crystal display device >>

(Viewing angle)

The viewing angle was measured for the liquid crystal display device manufactured by EZ-contrast by ELDIM. The viewing angle computed the contrast at the time of the white display and the black display of a liquid crystal cell, and made the viewing angle the angle which contrast becomes 100 in the diagonal direction.

(color)

The color measurement at the time of black display was performed by SR-3A by Topcon.

Color measurement was performed with a collapse angle of 60 ° (front reference) between the front face and the inclined image (azimuth angle of 45 degrees) to evaluate ((x-x ') ² + (y-y') ² ) ^1/2 .

In the formula, the front: (x, y) and the slope: (x ', y') are represented.

The obtained results are shown in Table 4.

As is clear from the results shown in Table 4, it can be seen that the liquid crystal display devices 1 to 16 of the present invention have a viewing angle (contrast of 100 or more) of more than 50 degrees, smaller than 0.09 of color change, and are superior to comparison.

Example 2

The polarizing plate was manufactured like Example 1 using the protective films A-U which have the retardation layer manufactured in Example 1, and the 3rd protective films Q and V-Z which do not provide a retardation layer, and are manufactured in FIG. ), An IPS mode liquid crystal display device was manufactured. In this case, the in-plane slow axis of the second protective film of the polarizing plate and the alignment direction of the liquid crystal cell are substantially orthogonal to each other.

When the viewing angle and color were evaluated in the same manner as in Example 1 using the manufactured IPS mode type liquid crystal display device, Example 1 was reproduced to show that the liquid crystal display device of the present invention has excellent contrast and color. Could.

Claims (6)

At least a first protective film, a first polarizing film, and a laminated retardation layer are arranged in this order, and in the laminated retardation layer, a second protective film containing cellulose ester satisfying the following formula (1), and the polarizing film Or the phase difference layer which fixed the orientation of the rod-shaped liquid crystal oriented perpendicular to the surface of a 2nd protective film is laminated | stacked, and the following at the wavelength of 590 nm of 23 degreeC, 55% RH of the said 2nd protective film and the said retardation layer Retardation Ro and Rt represented by Equations 3 and 4 are respectively 2nd protective film: Ro: 30-115 nm               Rt: 100 to 250 nm               Rt / Ro: 1.6 to 4.4 Retardation layer: Ro: 0 to 10 nm           Rt: -100 to -400 nm, The laminated retardation layer has an optical axis in plane, and the retardation at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH is Ro: 30 to 105 nm, Rt: -300 to 25 nm, and the following Equation 5 , The wavelength dispersion characteristics defined by 6, 7, 8 D (Ro) 1: 0.9 to 1.0 D (Ro) 2: -9.5 to 0 nm D (Rt) 1: 0.3 to 0.9 D (Rt) 2: -100 to -10 nm, The absolute value of the angle which the transmission axis of the said polarizing film and the in-plane slow axis of a said 2nd protective film make is in the range of 0-1 degree, The polarizing plate characterized by the above-mentioned. &Quot; (1) &quot; 2.00≤ (X + Y) ≤2.60 (Wherein, as the degree of substitution of the acyl group of the cellulose ester, X represents the degree of acetyl group substitution and Y represents the degree of propionyl group substitution.) &Quot; (3) &quot; Ro = (nx-ny) xd &Quot; (4) &quot; Rt = ((nx + ny) / 2-nz) × d (Wherein the refractive index of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer is in the slow axis direction in the plane of nx, and the refractive index in the direction orthogonal to the slow axis in the plane is ny, in the thickness direction Refractive index nz and d represent the respective thickness (nm)) &Quot; (5) &quot; D (Ro) 1 = Ro (630) / Ro (480) &Quot; (6) &quot; D (Ro) 2 = Ro (630) -Ro (480) &Quot; (7) &quot; D (Rt) 1 = | Rt (630) / Rt (480) | &Quot; (8) &quot; D (Rt) 2 = Rt (480) -Rt (630) (In formula, Ro (480), Ro (630) are the retardation Ro values at 480 nm and 630 nm, respectively, at 23 degreeC and 55% RH, and Rt (480), Rt (630) are respectively 480nm, Retardation Rt value at 630 nm) The polarizing plate of claim 1, wherein the cellulose ester satisfies the following Equation 2. &Quot; (2) &quot; 0.10? Y? The method of claim 1, wherein the first surface of the second protective film faces the polarizing film, and the second surface of the second protective film facing the first surface faces the phase difference layer. Polarizing plate. The polarizing plate of claim 1, wherein the retardation layer is disposed between the second protective film and the polarizing film. The liquid crystal cell which a liquid crystal molecule orientates in parallel with a glass substrate at the time of black display, and the orientation direction on both glass substrate sides is parallel, a 3rd protective film, a 2nd polarizing film, and the polarizing plate of Claim 1 The 3rd protective film has Ro: 0-5 nm, Rt which has a polarizing plate comprised by the protective film of 4, and is in parallel with the in-plane slow axis of the 2nd protective film of the said polarizing plate of Claim 1, and the orientation direction of a liquid crystal cell. : -10 to 10 nm, and the third protective film has a film thickness of 20 to 45 µm. The liquid crystal cell which a liquid crystal molecule orientates in parallel with a glass substrate at the time of black display, and the orientation direction on both glass substrate sides is parallel, a 3rd protective film, a 2nd polarizing film, and the polarizing plate of Claim 1 It has a polarizing plate comprised by the protective film of 4, the in-plane slow axis of the 2nd protective film of the said polarizing plate of Claim 1, and the orientation direction of a liquid crystal cell are orthogonal, and a 3rd protective film is Ro: 0-5 nm, Rt : -10 to 10 nm, and the third protective film has a film thickness of 20 to 45 µm.

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