KR20070022598A - Producing method of optical compensation film, optical compensation film, polarizing plate and liquid crystal display - Google Patents

Abstract

(Problem) To provide the method which has the outstanding optical compensation function with respect to the OCB system liquid crystal display device, and can manufacture stably and continuously the optical compensation film with small optical deviation. Providing the optical compensation film obtained by the method, the polarizing plate using this, and a liquid crystal display device.

(Solution means) Process of apply | coating the coating liquid containing a polymeric liquid crystal compound on a support body, and forming a liquid crystal compound layer; Drying the liquid crystal compound layer, and then aligning the liquid crystal compound and fixing the alignment to form an optically anisotropic layer; And after fixing the orientation of the said liquid crystal compound, Furthermore, by the manufacturing method of the optical compensation film which has a process of heating the said optically anisotropic layer at the heating temperature of 40 degreeC-150 degreeC, and the heating time 5 second-3000 second, and the method The obtained optical compensation film, the polarizing plate using this, and a liquid crystal display device.

Optical compensation film, polarizer, liquid crystal display

Description

Manufacturing method of optical compensation film, optical compensation film, polarizing plate and liquid crystal display device {PRODUCING METHOD OF OPTICAL COMPENSATION FILM, OPTICAL COMPENSATION FILM, POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY}

1 is a schematic view showing an example of a pixel region of a liquid crystal display of the present invention.

2 is a schematic view showing an example of a liquid crystal display of the present invention.

3 is a schematic view showing another example of the liquid crystal display of the present invention.

* Explanation of symbols for main parts of drawings *

1: liquid crystal element pixel region

2: pixel electrode

3: display electrode

4: rubbing direction

5a, 5b: director of liquid crystalline compound in black display

6a, 6b: director of liquid crystalline compound at the time of white display

7a, 7b, 19a, 19b: protective film for polarizing film

8, 20: polarizing film

9, 21: polarization transmission axis of the polarizing film

10: first phase difference region

11: slow axis of the first retardation region

12: second phase difference region

13, 17: cell substrate

14, 18: cell substrate rubbing direction

15: liquid crystal layer

16: slow axis direction of liquid crystal layer

Patent Document 1: Japanese Patent Application Laid-Open No. 2-247602

Patent Document 2: Japanese Patent Application Laid-Open No. 7-191217

Patent Document 3: European Patent No. 0911656A2

Patent Document 4: Japanese Patent Application Laid-Open No. 9-211444

Patent Document 5: Japanese Patent Application Laid-Open No. 11-316378

This invention relates to the optical compensation film which has the optically anisotropic layer which orientation-fixed the polymeric liquid crystal compound, its manufacturing method, and the polarizing plate and liquid crystal display device using the same.

BACKGROUND ART An optical film having a layer in which a liquid crystal compound is highly aligned and fixed has been recently developed for various applications, such as an optical compensation film of a liquid crystal display, a brightness enhancement film, and an optical compensation film of a projection display device, among which optical of a liquid crystal display device is used. The development as a compensation film is dazzling. Usually, a liquid crystal display device is provided with a polarizing plate and a liquid crystal cell. In the TN-type TFT liquid crystal display device which is the mainstream now, the optical compensation film is inserted between a polarizing plate and a liquid crystal cell, and the liquid crystal display device with high display quality is implement | achieved. However, in this configuration, the thickness of the liquid crystal display device itself becomes thick and cannot sufficiently respond to the request for thinning.

On the other hand, by using the elliptically polarizing plate which has a retardation film (optical compensation film) and a protective film in the other side on one side of a polarizing film, the invention which can make front contrast high without thickening a liquid crystal display device is proposed ( See, for example, Patent Document 1). By the way, in the retardation film of the said structure, sufficient viewing angle improvement effect was not acquired and there existed a problem that the display quality of a liquid crystal display device fell.

At present, by using an optical compensation film coated with an optically anisotropic layer formed from a discotic (discrete) compound on a transparent support as a protective film of a polarizing plate, the problem of viewing angle is solved without thickening the liquid crystal display device. (See, for example, patent documents 2 and 3).

In recent years, the demand for liquid crystal televisions has increased, and in liquid crystal televisions, the enlargement and the high brightness progress, and the delicate optical deviation becomes a problem. In particular, the OCB type liquid crystal display device having excellent moving image suitability, which is an important factor for television, is expected to be a very big problem because the display principle is a birefringence method. For example, Patent Documents 4 and 5 apply an optical compensation film having a layer made of a liquid crystal compound to an OCB type liquid crystal display device, which can cope with moving images and solve problems such as viewing angle.

The present invention provides a method of stably and continuously producing an optical compensation film having an excellent optical compensation function and an optical compensation film having a small optical deviation with respect to a liquid crystal display device, particularly an OCB type liquid crystal display device having a fast response speed and moving image aptitude. An object of the present invention is to provide an optical compensation film having excellent optical compensation function and small optical deviation.

In addition, the present invention has a polarizing function and has an excellent optical compensation function for a liquid crystal display device, in particular, an OCB type liquid crystal display device having a fast response speed and moving image aptitude, which has a small optical deviation and a thinner liquid crystal display device. An object of the present invention is to provide a polarizing plate that can also contribute to.

Moreover, an object of this invention is to provide the liquid crystal display device which can display the image with high display quality, especially the OCB system liquid crystal display device with fast response speed and moving image aptitude.

The said subject is achieved by the following means.

[1] a step of applying a coating liquid containing a polymerizable liquid crystal compound on the surface or the support of the support to form a liquid crystal compound layer;

Simultaneously or after drying the liquid crystal compound layer, orienting the liquid crystal compound at a temperature above the liquid crystal transition temperature, and fixing the orientation to form an optically anisotropic layer; And

Fixing the alignment of the liquid crystal compound and then heating the optically anisotropic layer;

As a manufacturing method of an optical compensation film having

The heating temperature in the process of heating the said optically anisotropic layer is 40 degreeC-150 degreeC, and a heat time is 5 second-3000 second, The manufacturing method of the optical compensation film characterized by the above-mentioned.

[2] An optical compensation film having a support and an optically anisotropic layer formed by using a polymerizable liquid crystal compound on the support, wherein the optical compensation film is produced by the production method described in [1] above.

[3] The optical compensation film according to the above [2], wherein the polymerizable liquid crystal compound is a discotic liquid crystal compound having a polymerizable group.

[4] A polarizing plate, comprising the optical compensation film and polarizing film according to the above [2] or [3].

[5] A liquid crystal display device comprising the optical compensation film described in [2] or [3] above or the polarizing plate described in [4] above.

[6] The liquid crystal display device according to the above [5], wherein the display method is an OCB method, an ECB method or an IPC.

Moreover, in this invention, the following form is also preferable.

[7] A roll-shaped optical compensation film in which the optical compensation film according to the above [2] or [3] has a long shape and is wound in a roll shape, wherein the molecular symmetry axis of the polymerizable liquid crystal compound in the optically anisotropic layer is used. The average direction is 43 degrees-47 degrees with respect to a longitudinal direction, The roll-shaped optical compensation film characterized by the above-mentioned.

[8] A roll-like optical compensation film according to [7], wherein an oriented film is provided between the support and the optically anisotropic layer.

[9] The rolled optical compensation film described in [8], wherein the alignment film is made of polyvinyl alcohol or modified polyvinyl alcohol crosslinked by a reaction with a crosslinking agent.

[10] The rolled optical compensation film according to any one of [7] to [9], wherein the polymerizable liquid crystal compound is a discotic liquid crystal compound having a polymerizable group.

To practice the invention  Best form for

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

[Optical Compensation Film]

The optical compensation film of this invention is an optical compensation film which has a support body and the optically anisotropic layer formed from the polymeric liquid crystal compound (henceforth a liquid crystal compound hereafter) on this support body. In order to orient the liquid crystal compound of the optically anisotropic layer, it is preferable to form an alignment film on the support or the support, and to rub the surface thereof.

The researches of the present inventors have found that the cause of the optical deviation is a slight thickness variation of the optically anisotropic layer and a local and subtle deviation of the alignment direction of the liquid crystal compound. Moreover, although the mechanism is not clear, it discovered that the optical deviation was remarkably reduced by making thickness of the liquid crystal compound thin.

One method of reducing the thickness while maintaining the optical compensating ability of the optically anisotropic layer is a method of curing the liquid crystal compound at the lowest possible temperature. Specifically, the method described in Unexamined-Japanese-Patent No. 10-293210 and Unexamined-Japanese-Patent No. 2000-9936 can be applied. However, according to this method, since alignment fixation of a liquid crystal compound becomes low temperature, the problem of adhesiveness with the alignment film (or support body) in which the intensity | strength of the liquid crystal compound layer itself falls falls, etc. have arisen.

By the intensive study of the present inventors, it was found that the above problem is solved by a very simple method of heating a film after immobilization of the polymerizable liquid crystal compound. It is presumed that the reason is that the radicals generated by the exterior at the time of immobilization remain after immobilization, and the polymerization proceeds by heating before the radicals are deactivated.

The orientation direction of the said liquid crystal compound refers to the average direction of the molecular symmetry axis of the liquid crystal compound in an optically anisotropic layer, and corresponds with the average direction of the orthographic projection to the support surface of the molecular symmetry axis of a liquid crystal compound normally.

It is preferable to manufacture the optical compensation film of this invention in roll shape, and after cut | disconnecting to a desired shape, you may attach to a liquid crystal display device as an optical compensation film, and also use as a protective film of a polarizing plate, etc. Another structure of a liquid crystal display device After integrating with a member, it can also be attached to a liquid crystal display device. It is preferable to use the liquid crystal display device in a horizontal alignment mode (especially a reflective liquid crystal display device) or a band alignment mode. When applying the optical compensation film of this invention to the liquid crystal display of these modes, arrangement | positioning of an optically anisotropic layer, a support body, and a polarizing film is very important, About the detail in the case of using a discotic compound as a liquid crystal compound, Unexamined-Japanese-Patent No. 11 It is described in -316378, and is applicable also to embodiment of this invention.

Hereinafter, each structural member of the optical compensation film of this invention is demonstrated in detail.

<< support body >>

It is preferable that the support body used for this invention is transparent, and specifically, it is preferable that light transmittance is 80% or more. In consideration of the necessity to be cylindrically wound in the case of producing a roll-shaped optical compensation film, a transparent polymer film is preferable. As a polymer film which can be used as a support body, the polymer film which consists of a cellulose ester (for example, cellulose acetate, a cellulose diacetate), a norbornene-type polymer, polymethyl methacrylate, etc. is mentioned. Commercially available polymers (in norbornene-based polymers, ARTON (made by Nippon Synthetic Rubber Co., Ltd.) and Zeonex (manufactured by Nippon Xeon Co., Ltd.) (both trade names)) may be used. Especially, the film which consists of cellulose esters is preferable, and the film which consists of lower fatty acid esters of cellulose is more preferable. Lower fatty acid means a fatty acid having 6 or less carbon atoms. In particular, carbon number of 2 (cellulose acetate), 3 (cellulose propionate), or 4 (cellulose butyrate) is preferable. Particular preference is given to films consisting of cellulose acetate. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may also be used.

In addition, even if a polymer which is easily known to express birefringence such as polycarbonate and polysulfone, which is known in the art, can be used as a support in the present invention by controlling the expression of birefringence by modifying molecules as described in WO 00/26705 Can also be used.

When using the optical compensation film of this invention as a protective film or retardation film of a polarizing plate, it is preferable to use the cellulose acetate whose acelation degree is 55.0-62.5% as a polymer film. It is more preferable that the degree of acetization is 57.0 to 62.0%. Here, the degree of acetylation means the amount of bound acetic acid per cellulose unit mass. Acetization degree is calculated | required by the measurement and calculation of the acetylation degree in ASTM: D-817-91 (test methods, such as a cellulose acetate).

It is preferable that it is 250 or more, and, as for the viscosity average polymerization degree (DP) of cellulose acetate, it is more preferable that it is 290 or more. Moreover, it is preferable that cellulose acetate has narrow molecular weight distribution of Mw / Mn (Mw is mass mean molecular weight, Mn is number average molecular weight) by gel permeation chromatography. As a specific value of Mw / Mn, it is preferable that it is 1.0-4.0, It is more preferable that it is 1.0-1.65, It is most preferable that it is 1.0-1.6.

In cellulose acetate, the hydroxyl of 2-position, 3-position, and 6-position of cellulose is not substituted uniformly, and there exists a tendency for substitution degree of 6-position to become small. In the polymer film used as a support body, it is preferable that the 6-position substitution degree of a cellulose is the same grade or many compared with 2-position and 3-position. It is preferable that the substitution degree ratio of 6-position with respect to the sum total of substitution degree of 2nd-position, 3rd-position, and 6-position is 30-40%, It is more preferable that it is 31-40%, It is most preferable that it is 32-40%. . It is preferable that substitution degree of a 6-position is 0.88 or more. In addition, the substitution degree of each position can be measured by NMR.

Cellulose acetate having a high 6-position substitution degree is shown in Synthesis Example 1 described in paragraphs 0043 to 0044 of JP-A-11-5851, Synthesis example 2 described in paragraphs 0048 to 0049, and synthesis example described in paragraphs 0051 to 0052. It can be synthesized by referring to the method of 3.

Re retardation value and Rth retardation value of a support body are defined by following formula (I) and (II), respectively.

Formula (I) Re = (nx-ny) × d

Formula (II) Rth = {(nx + ny) / 2-nz} × d

In formulas (I) and (II), nx is a refractive index in the slow axis direction (the direction in which the refractive index becomes maximum) in the support plane, ny is a refractive index in the fast axis direction (the direction in which the refractive index becomes minimum) in the support plane, nz Is the refractive index of the thickness direction of a support body, d is the thickness of the film which makes a unit nm.

It is preferable that the Rth retardation value (measurement wavelength (lambda) = 590nm) of the support body used for this invention is 40 nm-400 nm, and it is preferable that Re-retardation value (measurement wavelength (lambda == 590 nm)) is 0-70 nm. Do.

When attaching two optical compensation films of this invention using a cellulose acetate film as a support body to a liquid crystal display device, it is preferable that the Rth retardation value of the said cellulose acetate film is 40-250 nm. On the other hand, when attaching one optical compensation film of this invention using a cellulose acetate film as a support body to a liquid crystal display device, it is preferable that the Rth retardation value of the said cellulose acetate film is 150-400 nm.

Moreover, it is preferable that birefringence (the value which divided Re-retardation value by thickness) of a cellulose acetate film is 0.00025-0.00088. Moreover, it is preferable that birefringence (value which divided Rth retardation value by thickness) of the thickness direction of a cellulose acetate film is 0.00088-0.005.

When using a cellulose acetate film as a support body, it is preferable to contain a retardation increasing agent in a film, and about a preferable compound example and its manufacturing method, Unexamined-Japanese-Patent No. 2000-154261 and Unexamined-Japanese-Patent No. 2000-111914 It is described in.

`` Optical anisotropic layer ''

The optical compensation film of this invention has at least 1 optically anisotropic layer formed from the polymeric liquid crystal compound. Although the said optically anisotropic layer may be formed directly on the surface of a support body, it is more preferable to form an alignment film on a support body, and to form on the alignment film.

As a liquid crystal compound used for formation of an optically anisotropic layer, a rod-shaped liquid crystal compound and a discotic liquid crystal compound are mentioned. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a polymer liquid crystal or a low molecular liquid crystal, and also include those in which the low molecular liquid crystal is crosslinked so as not to exhibit liquid crystallinity.

<< rod-shaped liquid crystal compound >>

Rod-like liquid crystal compounds usable in the present invention include azomethines, azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyanos. Substituted phenylpyrimidines, alkoxy substituted phenylpyrimidines, phenyldioxanes, tolans and alkenylcyclohexylbenzonitriles are preferably used. Moreover, a metal complex is also contained in a rod-shaped liquid crystal compound. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystal compound in a repeating unit can also be used. In other words, the rod-like liquid crystal compound may be bonded to the (liquid crystal) polymer.

The rod-shaped liquid crystal compounds are described in Chapter 4, Chapter 7 and Chapter 11 of the Japanese Chemical Society, and the Chapter 3 of the Chapter 142 Committee of the Liquid Crystal Devices Handbook. have.

It is preferable that the birefringence of the rod-shaped liquid crystal compound used for this invention exists in the range of 0.001-0.7.

A rod-shaped liquid crystal compound has a polymeric group in order to fix the orientation state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

<< Discotic liquid crystal compound >>

Discotic liquid crystal compounds include C. Destrade et al., Mol. Cryst. 71, page 111 (1981), Benzene Derivatives, C. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics Lett, A, Vol. 78, 82 (1990), report on the Truthsen derivatives, B. Kohne et al., Angew. Chem. 96, page 70 (1984), cyclohexane derivatives and J. M. Lehn et al., J. Chem. Commun., Page 1794 (1985), by J. Zhang et al., J. Am. Chem. Soc. Azacrown-based or phenylacetylene-based macrocycles described in volume 116, page 2655 (1994).

The said discotic liquid crystal compound also includes the compound which shows liquid crystallinity of the structure which the linear alkyl group, the alkoxy group, or the substituted benzoyloxy group substituted radially as a side chain of a mother nucleus with respect to the mother nucleus of a molecular center. It is preferred that the molecule or aggregate of molecules is a compound having rotational symmetry and capable of imparting a certain orientation.

When the optically anisotropic layer is formed from the discotic liquid crystal compound, the compound finally contained in the optically anisotropic layer does not need to exhibit liquid crystal any more. For example, when a low molecular discotic liquid crystal compound has a group reacting with heat or light, the group reacts with heat or light, polymerizes or crosslinks, and forms an optically anisotropic layer by high molecular weight. The compound contained in the anisotropic layer may have already lost liquid crystallinity. Preferred examples of discotic liquid crystal compounds are described in Japanese Patent Laid-Open No. Hei 8-50206. Moreover, about the superposition | polymerization of a discotic liquid crystal compound, it is described in Unexamined-Japanese-Patent No. 8-27284.

In order to fix a discotic liquid crystal compound by superposition | polymerization, it is necessary to couple a polymeric group as a substituent to the disk-shaped core of a discotic liquid crystal compound. However, when a polymeric group is directly connected to a disk-shaped core, it becomes difficult to maintain an orientation state in a polymerization reaction. Thus, a linking group is introduced between the discotic core and the polymerizable group. Therefore, it is preferable that the discotic liquid crystal compound which has a polymeric group is a compound represented by following formula (III).

Formula (III) D (-L-Q) n

In formula (III), D is a disk-shaped core, L is a bivalent coupling group, Q is a polymeric group, n is an integer of 4-12.

An example of disk shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

(Formula 1)

(Formula 2)

(Formula 3)

(Formula 4)

In formula (III), the divalent linking group (L) is a divalent selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, -S- and combinations thereof. It is preferable that it is a linking group. The divalent linking group (L) is more preferably a divalent linking group in which at least two divalent groups selected from the group consisting of alkylene groups, arylene groups, -CO-, -NH-, -O- and -S- are combined. . The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. It is preferable that carbon number of the said alkylene group is 1-12. It is preferable that carbon number of the said alkenylene group is 2-12. It is preferable that carbon number of the said arylene group is 6-10.

Examples of the divalent linking group L are shown below. The left side is bonded to the disk-shaped core (D) and the right side is bonded to the polymerizable group (Q). AL means an alkylene group or an alkenylene group, AR means an arylene group. In addition, the alkylene group, the alkenylene group, and the arylene group may have a substituent (for example, an alkyl group).

L1: -AL-CO-O-AL-

L2: -AL-CO-O-AL-O-

L3: -AL-CO-O-AL-O-AL-

L4: -AL-CO-O-AL-O-CO-

L5: -CO-AR-O-AL-

L6: -CO-AR-O-AL-O-

L7: -CO-AR-O-AL-O-CO-

L8: -CO-NH-AL-

L9: -NH-AL-O-

L10: -NH-AL-O-CO-

L11: -O-AL-

L12: -O-AL-O-

L13: -O-AL-O-CO-

L14: -O-AL-O-CO-NH-AL-

L15: -O-AL-S-AL-

L16: -O-CO-AR-O-AL-CO-

L17: -O-CO-AR-O-AL-O-CO-

L18: -O-CO-AR-O-AL-O-AL-O-CO-

L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-

L20: -S-AL-

L21: -S-AL-O-

L22: -S-AL-O-CO-

L23: -S-AL-S-AL-

L24: -S-AR-AL-

The polymerizable group (Q) of Formula (III) is determined according to the kind of polymerization reaction. The polymerizable group (Q) is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

In formula (III), n is an integer of 4-12. The specific number is determined according to the kind of disk-shaped core (D). Moreover, although the combination of several L and Q may differ, the same thing is preferable.

About the orientation of the liquid crystal compound in an optically anisotropic layer, it orientates so that the average direction of the molecular symmetry axis of the liquid crystal compound in an optically anisotropic layer may be 43 degrees-47 degrees with respect to a longitudinal direction, for example.

In the hybrid orientation, the angle of molecular symmetry axis of the liquid crystal compound and the angle of the surface of the support are increased or decreased in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the support. The angle preferably decreases with increasing distance. Also, the change in angle may be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region in which the inclination angle does not change in the thickness direction.

The angle may increase or decrease as a whole even if it includes an area where the angle does not change. Moreover, it is preferable that an angle changes continuously.

The average direction of the molecular symmetry axis of a liquid crystal compound can generally be adjusted by selecting the material of a liquid crystal compound or an alignment film, or by selecting a rubbing process method. In addition, the molecular symmetry axis direction of the liquid crystal compound on the surface side (air side) can be adjusted by selecting the kind of additive generally used with a liquid crystal compound or a liquid crystal compound. Examples of the additive used with the liquid crystal compound include plasticizers, surfactants, polymerizable monomers and polymers. The change degree of the orientation direction of a molecular symmetry axis can also be adjusted by selection of a liquid crystal compound and an additive similarly to the above. It is preferable to make it compatible with the surface tension control of the coating liquid mentioned later especially about surfactant.

The plasticizer, surfactant, and polymerizable monomer used together with the liquid crystal compound have compatibility with the liquid crystal compound, and it is preferable not to change the inclination angle of the liquid crystal compound or to inhibit the orientation. Polymerizable monomers (for example, compounds having a vinyl group, vinyloxy group, acryloyl group and methacryloyl group) are preferable. It is preferable that the addition amount of the said compound exists in the range of 1-50 mass% generally with respect to a liquid crystal compound, and exists in the range of 5-30 mass%. Moreover, adhesiveness between an orientation film and an optically anisotropic layer can be improved when mixing and using the monomer whose polymerizable reactive functional group number is four or more.

When using a discotic liquid crystal compound as a liquid crystal compound, it is preferable to use the polymer which has a certain compatibility with a discotic liquid crystal compound, and changes the inclination angle of a discotic liquid crystal compound.

Examples of the polymer include cellulose esters. Preferred examples of the cellulose esters include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. In order not to inhibit the orientation of the discotic liquid crystal compound, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.1 to 8% by mass, more preferably 0.1 It is more preferable to exist in the range of-5 mass%.

70-300 degreeC is preferable and, as for the discotic nematic liquid crystal phase-solid state transition temperature of a discotic liquid crystal compound, 70-170 degreeC is more preferable.

It is preferable to perform the temperature at the time of orientation fixing below a discotic nematic liquid crystal phase-solid state transition temperature.

The post-heating after orientation fixing is demonstrated below.

In this invention, it is preferable that the thickness of an optically anisotropic layer is 0.1-20 micrometers, It is more preferable that it is 0.5-15 micrometers, It is most preferable that it is 1-10 micrometers.

<< alignment film >>

It is preferable that the optical compensation film of this invention has an oriented film between a support body and an optically anisotropic layer.

In the present invention, the alignment film is preferably a layer made of a crosslinked polymer. As the polymer used for the alignment film, any of polymers crosslinkable by themselves or polymers crosslinked by a crosslinking agent can be used. The alignment film is formed by reacting a polymer or a polymer having a functional group with a functional group between the polymers by light, heat or pH change; Or by crosslinking the polymers by introducing a linking group derived from the crosslinking agent between the polymers using a crosslinking agent which is a compound having high reaction activity; can do.

Orientation film which consists of a crosslinked polymer can be normally formed by apply | coating the coating liquid containing the said polymer or the mixture of a polymer and a crosslinking agent on a support body, and then heating.

In the rubbing process mentioned later, in order to suppress oscillation of an oriented film, it is preferable to make a crosslinking degree high. Regarding the amount (Mb) of the crosslinking agent added to the coating liquid, the value (1- (Ma / Mb)) obtained by subtracting the ratio (Ma / Mb) of the amount (Ma / Mb) of the amount of the crosslinking agent remaining after crosslinking by 1 was defined as the degree of crosslinking. In this case, the crosslinking degree is preferably 50% to 100%, more preferably 65% to 100%, and most preferably 75% to 100%.

In the present invention, the polymer used in the alignment film may be either a polymer crosslinkable by itself or a polymer crosslinked by a crosslinking agent. Of course, a polymer having both functions can also be used. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol acrylamide), styrene / vinyltoluene air Copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethyl cellulose, polyethylene, polypropylene and polycarbonate Compounds, such as a polymer and a silane coupling agent, are mentioned. Examples of preferred polymers are water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and gelatin, polyvinyl alcohol and modified polyvinyl alcohol are preferred. In particular, polyvinyl alcohol and modified polyvinyl alcohol can be mentioned.

Among the polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable. As polyvinyl alcohol, saponification degree is 70 to 100%, for example, saponification degree is 80 to 100%, and saponification degree is 85 to 95% more preferably, for example. As polymerization degree, the range of 100-3000 is preferable. Modified polyvinyl alcohols include copolymer-modified ones (for example, COONa, Si (OX) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ , Na, C ₁₂ H _25, etc.). Introduced), modified by chain transfer (modifying groups for example COONa, SH, C ₁₂ H ₂₅ The like are introduced Yes), there may be mentioned that a denatured by block polymerization (for example, a shift converter COOH, CONH _2, COOR, C ₆ being H _5, etc. is introduced), a modified product of polyvinyl alcohol, and the like. As polymerization degree, the range of 100-3000 is preferable. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferable, and more preferably unmodified or alkylthio modified polyvinyl alcohol having a saponification degree of 85 to 95%.

As a modified polyvinyl alcohol used for an oriented film, the reaction material of the compound represented by following General formula (1) and polyvinyl alcohol is preferable.

General formula (1)

(Formula 5)

Provided that R ¹ represents an unsubstituted alkyl group or an alkyl group substituted with an acryloyl group, a methacryloyl group or an epoxy group, W represents a halogen atom, an alkyl group or an alkoxy group, and X represents an active ester, an acid anhydride or an acid halide In order to show the atom group required in order, l represents 0 or 1, and n represents the integer of 0-4.

Moreover, the reaction material of the compound represented by following General formula (2) and polyvinyl alcohol as a modified polyvinyl alcohol used for an oriented film is also preferable.

General formula (2)

(Formula 6)

However, X <^1> represents the atomic group required in order to form an active ester, an acid anhydride, or an acid halide, and m shows the integer of 2-24.

As polyvinyl alcohol used for reacting with the compound represented by the said General formula (1) and (2), the said unmodified polyvinyl alcohol and the said copolymer-modified thing, ie, modified by chain transfer And modified products of polyvinyl alcohol, such as those modified or modified by block polymerization. Preferred examples of the specific modified polyvinyl alcohol are described in detail in Japanese Patent Application Laid-open No. Hei 8-338913.

When using hydrophilic polymers, such as polyvinyl alcohol, for an oriented film, it is preferable to control water content from a viewpoint of a film degree, It is preferable that it is 0.4%-2.5%, It is more preferable that it is 0.6%-1.6%. The moisture content can be measured by a commercially available Karl Fischer method of moisture content measurement.

Moreover, it is preferable that an oriented film is a film thickness of 10 micrometers or less.

Next, the manufacturing method of the optical compensation film of this invention is demonstrated.

[Method for Producing Optical Compensation Film]

The manufacturing method of the optical compensation film of this invention is a process of following (1)-(4), for example:

(1) performing a rubbing treatment on the surface of the support or the surface of the alignment film formed on the support;

(2) Process of apply | coating the coating liquid containing a polymeric liquid crystal compound on the said rubbed support body or the orientation film surface, and forming a liquid crystal compound layer;

(3) drying the liquid crystal compound layer at the same time or drying the liquid crystal compound at a temperature equal to or higher than the liquid crystal transition temperature, and fixing the orientation to form an optically anisotropic layer;

(4) After fixing the orientation of the liquid crystal compound, the step further comprises heating the optically anisotropic layer. The process can be carried out continuously.

In the manufacturing method of this invention, it is preferable that the film surface wind speed of the surface of the said liquid crystal compound layer poured in the direction other than the rubbing direction of the said rubbing process between orientation in the process of said (3) satisfy | fills following formula (1). Do.

Equation (1) 0.1 <V <5.0 × 10 ^-3 × η

In the formula, V is the film surface velocity (m / sec) on the surface of the liquid crystal compound layer, and η represents the viscosity (cp) of the liquid crystal compound layer at the alignment temperature of the liquid crystal compound.

Moreover, it is preferable that the film surface speed V is 0.1-2.5 * 10 <^-3> (eta).

According to the production method of the present invention, since the wind speed and direction of the wind blowing on the surface of the liquid crystal compound layer are controlled, the average direction of the molecular symmetry axis of the liquid crystal compound in the optically anisotropic layer is substantially 0 ° with respect to the desired direction. Preferably, an optical compensation film of preferably -2 ° to 2 °, more preferably -1 ° to 1 ° can be continuously and stably produced, which is suitable for mass production.

When the optical compensation film is applied to a liquid crystal display device, especially an OCB mode liquid crystal display device, the average direction of the molecular symmetry axis of the liquid crystal compound in the optically anisotropic layer and the in-plane slow axis of the support are substantially 45 °, that is, preferably Is preferably 43 ° to 47 °, more preferably 44 ° to 46 °, in order to exhibit an excellent optical compensation function. As described above, according to the manufacturing method of the present invention, since the average direction of the molecular symmetry axis can be manufactured to coincide with the desired direction, the angle between the average direction of the molecular symmetry axis and the in-plane slow axis of the support is easily within the above range. can do.

In addition, the in-plane slow axis of the support generally coincides with the longitudinal direction when the support is a long polymer film.

The manufacturing method of the present invention is also a preferable method for producing a roll-shaped optical compensation film. In other words,

(1 ') Process of performing a rubbing process to the surface of the elongate support body conveyed in the longitudinal direction, or the alignment film surface formed on the support body;

(2) Process of apply | coating the coating liquid containing a polymeric liquid crystal compound on the said rubbed support body or the orientation film surface, and forming a liquid crystal compound layer;

(3) drying the liquid crystal compound layer at the same time or drying the liquid crystal compound at a temperature equal to or higher than the liquid crystal transition temperature, and fixing the orientation to form an optically anisotropic layer;

(4) after fixing the orientation of the liquid crystal compound, further heating the optically anisotropic layer;

(5) process of winding up the laminated body of elongate shape in which the said optically anisotropic layer was formed; By carrying out continuously, a roll-shaped optical compensation film can be manufactured continuously and stably.

Moreover, the manufacturing method of this invention

1) In the process of (3) above, the coating layer is continuously irradiated to cure the polymerizable liquid crystal compound by polymerization and fixed in an orientation state, and then the process of (4) may be continuously performed. ; And / or

2) In the process of said (1), rubbing process with the rubbing roller, and / or before the process of said (2), rubbing process the surface of the said support body or the orientation film, You may perform the process of vibration damping; And / or

3) Before the process of said (5), you may include the inspection process which inspects by measuring the optical characteristic of the formed optically anisotropic layer continuously.

The detail of each of these processes is described in Unexamined-Japanese-Patent No. 9-73081.

Hereinafter, each process is demonstrated.

<< 1 process >>

In the step (1), a rubbing treatment is performed on the surface of the support or the surface of the alignment film formed on the support.

It is preferable to perform a rubbing process with a rubbing roller. It is preferable that it is 100 mm-500 mm, and, as for the diameter of the rubbing roller to be used, from a viewpoint of handling suitability and cloth life, it is more preferable that it is 200 mm-400 mm. It is preferable that the width of the rubbing roller is wider than the width of the support, and it is preferable that the width of the rubbing roller is not less than film width x? It is preferable to set the rotation speed of a rubbing roller low from a viewpoint of oscillation, and although it changes also with the orientation of a liquid crystal compound, it is preferable that it is 100 rpm-1000 rpm, and it is more preferable that it is 250 rpm-850 rpm.

In order to maintain the orientation of a liquid crystal compound even if the rotation speed of a rubbing roll is made low, it is preferable to heat the support body or orientation film at the time of rubbing. It is preferable that heating temperature is (Tg-50 degreeC of material)-(Tg + 50 degreeC of material) in the film surface temperature of a support body or an oriented film surface. When using the alignment film which consists of polyvinyl alcohol, it is preferable to control the environmental humidity of rubbing, It is preferable that it is 25% RH-70% RH as a relative humidity of 25 degreeC, and it is more preferable that it is 30% RH-60% RH. It is preferable and it is most preferable that they are 35% RH-55% RH.

Even when the optical compensation film to manufacture is not in roll shape, it is preferable from a viewpoint of productivity that a rubbing process is performed, conveying a support body.

It is preferable that it is 10 m / min-100 m / min from a viewpoint of productivity and a liquid-crystal orientation, and, as for the conveyance speed of a support body, it is more preferable that it is 15 m / min-80 m / min. The conveyance can be performed using various apparatuses conventionally used for conveyance of a film, and it does not restrict | limit especially about a conveyance system.

In addition, the alignment film can be produced by applying a coating liquid obtained by dissolving a material such as polyvinyl alcohol described above to water and / or an organic solvent and the like on the surface of the support and drying. Preparation of an oriented film can be performed before the said series of process, and you may produce an oriented film continuously on the surface of the support body conveyed.

<< 2 process >>

In the process of said (2), the coating liquid containing a liquid crystal compound (henceforth a coating liquid for optically anisotropic layer formation) is apply | coated to the said rubbing process surface. As a solvent used for preparation of the coating liquid for optically anisotropic layer formation, an organic solvent is used preferably. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethylsulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (e.g. methyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxyethane) Included. Alkyl halides and ketones are preferred. You may use together 2 or more types of organic solvents.

In order to produce a highly uniform optically anisotropic layer, it is preferable that the surface tension of the coating liquid for optically anisotropic layer formation is 25 mN / m or less, and it is more preferable that it is 22 mN / m or less.

In order to realize this low surface tension, the coating liquid for optically anisotropic layer formation contains surfactant or a fluorine compound, especially the repeating unit corresponded to the monomer of following (1), and the repeating unit corresponded to the monomer of following (2). It is preferable to contain fluorine-type polymers, such as a fluoro aliphatic group containing copolymer.

(1) A fluoro aliphatic group-containing monomer represented by the following general formula (3)

(2) poly (oxyalkylene) acrylates and / or poly (oxyalkylene) methacrylates

General formula (3)

(Formula 7)

In the general formula (3), R ² represents a hydrogen atom or a methyl group, X is an oxygen atom, a sulfur atom or -N (R ³⁾ - represents the, p is an integer of 1 ~ 6, q is 2 or 3 Represents an integer. R ³ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

3000-100,000 are preferable and, as for the mass mean molecular weight of the said fluorine-type polymer added in the coating liquid for optically anisotropic layer formation, 6,000-80,000 are more preferable. Moreover, 0.005-8 mass% is preferable with respect to the coating liquid composition (coating component except a solvent) which mainly makes a liquid crystal compound, and, as for the addition amount of the said fluorine-type polymer, 0.01-1 mass% is more preferable, 0.05-0.5 mass% is further more desirable. If the added amount of the fluorine-based polymer is less than 0.005% by mass, the effect is insufficient. If the amount of the fluorine-based polymer is more than 8% by mass, drying of the coating film may not be sufficiently performed, or performance as an optical compensation film (for example, uniformity of retardation). Adversely affects.

Coating of the coating liquid for forming the optically anisotropic layer to the rubbing treatment surface can be performed by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method). have. The application amount can be appropriately determined based on the desired thickness of the optically anisotropic layer.

<< 3 process >>

In the process of said (3), an optically anisotropic layer is formed by fixing the orientation of a liquid crystal compound from the liquid crystal compound layer which consists of the said coating liquid apply | coated. That is, at the same time as drying the said coating liquid applied or drying, the liquid crystal compound of the said coating liquid is orientated at the temperature more than liquid crystal transition temperature, and the orientation is fixed and an optically anisotropic layer is produced. The liquid crystal compound is in a desired orientation by the polymerization reaction. The drying temperature can be determined in consideration of the boiling point of the solvent used in the coating liquid and the materials of the support and the alignment film. The orientation temperature of a liquid crystal compound can be determined according to the liquid crystal phase-solid state transition temperature of the liquid crystal compound to be used. When using a discotic liquid crystal compound as a liquid crystal compound, 70-300 degreeC is preferable and 70-170 degreeC of an orientation temperature is more preferable.

Moreover, when a liquid crystal compound is a liquid crystal state, it is preferable that it is 10cp-10000cp, and, as for the viscosity of a liquid crystal compound layer, it is more preferable that it is 100cp-1000cp. If the viscosity is too low, it is susceptible to wind in orientation and very high wind speed / wind control is required for continuous production. On the other hand, if the viscosity is high, it is difficult to be affected by the wind, but the orientation of the liquid crystal is slowed down, and the productivity is very deteriorated.

The viscosity of the liquid crystal compound layer can be appropriately controlled according to the molecular structure of the liquid crystal compound. Moreover, the method of adjusting to a desired viscosity by using an appropriate amount of the above-mentioned additives (especially a cellulose polymer etc.), a gelling agent, etc. is used preferably.

Heating can be performed by blowing the warm air of predetermined temperature, or conveying the inside of the heating chamber hold | maintained at predetermined temperature.

The wind speed and direction of the warm air at this time are controlled as shown in the above expression (1), except for the rubbing direction that touches the liquid crystal compound layer.

The alignment state of the oriented liquid crystal compound is maintained and fixed, and fixing of the liquid crystal compound at the time of forming an optically anisotropic layer is performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. Photopolymerization reaction is preferred.

Examples of photopolymerization initiators include α-carbonyl compounds (see US Pat. No. 23,684, 197 to each specification in US Pat. No. 2367670), acyloinether (as described in US Pat. No. 2448828), α-hydrocarbon substituted aromatic acyl compounds ( US Patent No. 2722512, multinucleated quinone compounds (US Pat. No. 3046127, described in each specification of US Pat. No. 2951758), and combinations of triarylimidazole dimers and p-aminophenylketones (US Pat. No. 3549367) ), Acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, described in US Pat. No. 4,339850) and Oxadiazole compounds (described in US Pat. No. 4,229,970).

It is preferable to exist in the range of 0.01-20 mass% of coating liquid solid content, and, as for the usage-amount of a photoinitiator, it is more preferable to exist in the range of 0.5-5 mass%.

It is preferable to use ultraviolet-ray for the light irradiation for advancing and fixing superposition | polymerization of a liquid crystal compound. Irradiation energy ranges from 20 mJ / cm 2 to 50 J / cm 2 It is preferable to exist in the range of, It is more preferable to exist in the range of 20-5000mJ / cm <2>, It is still more preferable to exist in the range of 100-800mJ / cm <2>. Moreover, in order to accelerate photopolymerization reaction, you may irradiate light under heating conditions. Light irradiation can be performed by letting the support body which apply | coated the coating liquid for optically anisotropic layer formation through the conveyance path in which one or more light sources were arrange | positioned at any one position of a top, bottom, left and right.

<< 4 process >>

The process of said (4) is a process of heating the said optically anisotropic layer further after fixing the orientation of a liquid crystal compound.

In process (4), heating temperature is 40 degreeC-150 degreeC, and 50 degreeC-130 degreeC is more preferable. It is preferable to make an upper limit temperature below the glass transition point of the support body used.

Moreover, it is preferable to perform heating time for 5 second-3000 second, and 10 second-2800 second are more preferable. In addition, the shorter the time from orientation fixing to post-heating, the more effective it is, and it is preferable to carry out for 0.1 second to 6000 seconds. However, since some effect is recognized even if it heats the film which passed over the said time, it does not restrict | limit in particular.

MEANS TO SOLVE THE PROBLEM This inventor discovered that the intensity | strength of a polymeric liquid crystal layer or the adhesive force between this liquid crystal layer and an alignment film improves remarkably by the post-heating after immobilization. Although the factors are not separated correctly, it is estimated that the radical which generate | occur | produces at the time of orientation fixation is activated by post-heating, and a polymerization reaction advances even after the orientation of the liquid crystal layer is fixed. It is thought that these factors will be revealed by the present inventor in the near future.

If the heating temperature is less than 40 ° C., the strength of the liquid crystal layer and the adhesion of the alignment film are not sufficiently improved. If the heating temperature is higher than 150 ° C., a relatively low Tg support may cause a change in characteristics of the support. Not desirable Moreover, when heating time is less than 5 second, the adhesive force improvement with the intensity | strength of a liquid crystal layer and an orientation film is not enough, and when it exceeds 3000 second, it is unpreferable from a productivity viewpoint.

When manufacturing a roll-shaped optical compensation film, the process of said (5) is performed following the process of said (4). Before shifting to the process of (5), a protective layer may be formed on the optically anisotropic layer produced in the process of (4). For example, you may laminate the protective layer film previously produced on the surface of the optically anisotropic layer produced in elongate shape.

In the process of said (5), the laminated body of the elongate shape in which the said optically anisotropic layer was formed is wound up. Winding may be performed by winding the support body which has an optically anisotropic layer conveyed continuously, for example to a cylindrical core.

Since the optical compensation film obtained by the process of said (5) is a roll form, the handling is easy also when it manufactures in large quantities. It can be stored and returned in its original form.

All the conditions, apparatuses, etc. of each process of the manufacturing method of this invention can apply all the conditions and apparatuses of Unexamined-Japanese-Patent No. 9-73081.

[Polarizing Plate]

The polarizing plate of this invention has the optical compensation film and polarizing film of this invention. When using a roll-shaped optical compensation film, after cutting a roll-shaped optical compensation film into desired shape, such as a rectangular shape, you may adhere with a polarizing film, and after attaching with a long polarizing film, You can also cut into shapes. In the case of a roll-shaped optical compensation film, it can also adhere by a long polarizing film and a roll-to-roll, and is advantageous in terms of productivity.

The polarizing plate of the present invention has not only a polarizing function but also an excellent optical compensation function, and can be easily attached to a liquid crystal display device. Moreover, the aspect which made the said optical compensation film the protective film of a polarizing film contributes to thickness reduction of a liquid crystal display device.

Hereinafter, the specific example of the material used for each member, a manufacturing method, etc. are demonstrated.

<< polarizing film >>

The polarizing film used for the polarizing plate of this invention is Optiva Inc. The coating type polarizing film represented by this, or the polarizing film which consists of a binder and an iodine or a dichroic dye is preferable. The iodine and the dichroic dye express polarization performance by being oriented in a binder. It is preferable that the iodine and the dichroic dye are oriented along the binder molecule, or the dichroic dye is oriented in one direction by self-organization such as liquid crystal. Commercially available polarizing films are generally produced by immersing a stretched polymer in a solution of iodine or a dichroic dye in a bath and infiltrating an iodine or a dichroic dye into a binder. In addition, commercially available polarizing films have an iodine or a dichroic dye distributed at about 4 μm (about 8 μm in total) from the polymer surface, and a thickness of at least 10 μm is required to obtain sufficient polarization performance. Permeability can be controlled by the solution concentration of an iodine or dichroic dye, the temperature of the copper bath, and the immersion time.

As mentioned above, it is preferable that the minimum of binder thickness is 10 micrometers. The thinner the upper limit of the thickness, the thinner the better in view of the light leakage phenomenon generated when the polarizing plate is used in the liquid crystal display device. It is preferable that it is currently commercially available polarizing plate (about 30 micrometers) or less, 25 micrometers or less are preferable, and 20 micrometers or less are more preferable. If it is 20 micrometers or less, a light leakage phenomenon will not be observed by a 17-inch liquid crystal display device.

The binder of the polarizing film may be crosslinked. You may use the polymer itself which can crosslink as a binder of a polarizing film. A polymer having a functional group or a polymer obtained by introducing a functional group into the polymer may be subjected to light, heat or pH change to react the functional group and crosslink between the polymers to form a polarizing film. Moreover, you may introduce a crosslinked structure into a polymer with a crosslinking agent. It can form by crosslinking between binders by introduce | transducing the coupling group derived from a crosslinking agent between binders using the crosslinking agent which is a compound with high reaction activity.

Crosslinking can generally be performed by apply | coating the coating liquid containing a crosslinkable polymer or the mixture of a polymer and a crosslinking agent on a transparent support body, and then heating. Since durability should just be ensured at the end of the final product, the crosslinking treatment may be performed at any stage until the final polarizing plate is obtained.

As mentioned above, as a binder of a polarizing film, the polymer which can be crosslinked by itself, or the polymer crosslinked by a crosslinking agent can be used. Examples of the polymer include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylol acrylamide), polyvinyl toluene, chlorosulfonated polyethylene, nitrocellulose , Chlorinated polyolefins (e.g. polyvinyl chloride), polyesters, polyimides, polyvinyl acetate, polyethylene, carboxymethylcellulose, polypropylene, polycarbonates and their copolymers (e.g. acrylic / methacrylic acid copolymers, styrene / maleic Mid copolymer, styrene / vinyltoluene copolymer, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer). You may use a silane coupling agent as a polymer. Water-soluble polymers (e.g. poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, poly Most preferred are vinyl alcohol and modified polyvinyl alcohol.

70-100% is preferable, as for the saponification degree of polyvinyl alcohol and modified polyvinyl alcohol, 80-100% is more preferable, 95-100% is the most preferable. As for the polymerization degree of polyvinyl alcohol, 100-5000 are preferable.

Modified polyvinyl alcohol is obtained by introducing a modifying group by copolymerization modification, chain transfer modification or block polymerization modification to polyvinyl alcohol. In copolymerization modification, COONa, Si (OH) ₃ , N (CH ₃ ) ₃ Cl, C ₉ H ₁₉ COO, SO ₃ Na, and C ₁₂ H ₂₅ can be introduced as the modifying group. In the chain transfer modification, COONa, SH and C ₁₂ H ₂₅ can be introduced as the modifying group. As for the polymerization degree of modified polyvinyl alcohol, 100-3000 are preferable. The modified polyvinyl alcohol is described in Japanese Patent Laid-Open Nos. 8-338913, 9-152509, and 9-316127.

Unmodified polyvinyl alcohol and alkylthio modified polyvinyl alcohol having a saponification degree of 85 to 95% are particularly preferred.

Polyvinyl alcohol and modified polyvinyl alcohol may use 2 or more types together.

Crosslinking agents are described in US Pat. No. 23297, and can be used in the present invention. Moreover, a boron compound (for example, boric acid, borax) can also be used as a crosslinking agent.

If the crosslinking agent of a binder is added a lot, the heat-and-moisture resistance of a polarizing film can be improved. However, when 50 mass% or more of crosslinking agents are added with respect to a binder, the orientation of an iodine or a dichroic dye will fall. 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The binder contains a crosslinking agent that does not react to some extent even after the crosslinking reaction is completed. However, it is preferable that it is 1.0 mass% or less in a binder, and, as for the quantity of the remaining crosslinking agent, it is more preferable that it is 0.5 mass% or less. When a crosslinking agent is contained in the quantity exceeding 1.0 mass% in a binder, a problem may arise in durability. That is, when the polarizing film with much residual amount of a crosslinking agent is attached to a liquid crystal display device, and is left to stand for a long time in long-term use or the atmosphere of high temperature, high humidity, the fall of polarization degree may generate | occur | produce.

As the dichroic dye, an azo dye, a stilbene dye, a pyrazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye or an anthraquinone dye is used. It is preferable that a dichroic dye is water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). Examples of dichroic dyes include CI Direct Yellow 12, CI Direct Orange 39, CI Direct Orange 72, CI Direct Red 39, CI Direct Red 79, CI Direct Red 81, CI Direct Red 83, and CI Direct. Red 89, CI direct violet 48, CI direct blue 67, CI direct blue 90, CI direct green 59, and CI acid red 37 are included. For dichroic dyes, Japanese Patent Application Laid-Open No. H1-161202, 1-172906, 1-172907, 1-183602, 1-248105, 1-265205, and 7-261024 Each publication has a description.

Dichroic dyes are used as free acids or salts such as alkali metal salts, ammonium salts or amine salts. By mix | blending two or more types of dichroic dyes, the polarizing film which has various colors can be manufactured. When the polarization axis is orthogonal, a polarizing film using a black compound (pigment), or a polarizing film or polarizing plate in which various dichroic molecules are blended to have a black color is preferable because both of the single plate transmittance and the polarization rate are excellent.

<< production of polarizing film >>

The polarizing film is preferably dyed with iodine or a dichroic dye after stretching or stretching (stretching method) or rubbing (rubbing method) by inclining the binder 10 to 80 degrees with respect to the longitudinal direction (MD direction) of the polarizing film in terms of yield. Do. It is preferable to extend | stretch so that the inclination-angle may match the angle which the transmission axis of the two polarizing plates attached to the both sides of the liquid crystal cell which comprises LCD, and the longitudinal or horizontal direction of a liquid crystal cell make. Typical inclination angle is 45 degrees. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective and transflective LCDs, and it is desirable that the stretching direction can be arbitrarily adjusted according to the LCD design.

In the case of the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may perform wet extending | stretching in the state immersed in water. The stretching ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretching ratio of wet stretching is preferably 3.0 to 10.0 times. An extending process may be divided into several times including diagonal stretch. By dividing into several times, it can extend | stretch more uniformly even in high magnification extending | stretching. Before diagonal drawing, you may perform some extending | stretching (a grade which prevents shrinkage of the width direction) horizontally or vertically. Stretching can be performed by performing tenter stretching in biaxial stretching at different stages. The biaxial stretching is the same as the stretching method performed in normal film film production. In biaxial stretching, since it is stretched by different speeds left and right, it is necessary to make the thickness of the binder film before extending | stretching different from right to left. In the flexible film production, the taper is formed on the die, so that the left and right difference can be formed in the flow rate of the binder solution.

As mentioned above, the binder film 10-80 degree diagonally stretched with respect to the conveyance direction of a polarizing film is manufactured.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment step of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a predetermined direction using paper, gauze, felt, rubber or nylon, or polyester fibers. Generally, it is performed by rubbing about several times using the cloth which averaged the fiber of uniform length and thickness. It is preferable to implement using the rubbing roll whose roundness, cylinder degree, and shake (eccentricity) of a roll itself are all 30 micrometers or less. As for the wrap angle of the film to a rubbing roll, 0.1-90 degrees is preferable. However, as described in Japanese Unexamined Patent Application Publication No. Hei 8-160430, a stable rubbing treatment can also be obtained by winding 360 degrees or more.

When rubbing a long film, it is preferable to convey a film at a speed | rate of 1-100 m / min in the state of constant tension with a conveying apparatus. It is preferable that the rubbing roll is free to rotate in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When using for a liquid crystal display device, 40-50 degrees are preferable. 45 ° is particularly preferred.

It is preferable to arrange | position a protective film on both surfaces of a polarizing film, and it is preferable to use the optical compensation film of this invention as a protective film of one side. For example, the laminated body laminated | stacked in order of a protective film / polarizing film / support body / optical anisotropic layer, and a protective film / polarizing film / support body / orientation film / optical anisotropic layer is preferable. However, it is not limited to this structure, You may adhere the surface side of a polarizing film and an optically anisotropic layer. An adhesive may be used for adhesion, For example, polyvinyl alcohol-type resin (containing the modified polyvinyl alcohol by acetoacetyl group, sulfonic acid group, carboxyl group, and oxyalkylene group) and boron compound aqueous solution can be used as an adhesive agent. Especially, polyvinyl alcohol-type resin is preferable.

It is preferable to exist in the range of 0.01-10 micrometers after drying, and it is especially preferable to exist in the range which is 0.05-5 micrometers after drying.

Moreover, when using the polarizing plate of this invention for a liquid crystal display device, it is preferable to provide an antireflection layer in the visual recognition side surface, and you may combine this antireflection layer with the protective layer of the visual recognition side of a polarizing film. It is preferable to make internal noise of an antireflection layer into 50% or more from a viewpoint of suppressing the change of the color by the time of a liquid crystal display device. As a preferable specific example of these, they are described in Unexamined-Japanese-Patent No. 2001-33783, Unexamined-Japanese-Patent No. 2001-343646, and Unexamined-Japanese-Patent No. 2002-328228.

In order to raise the contrast ratio of a liquid crystal display device, it is preferable that the transmittance | permeability of a polarizing plate is high, and it is preferable that a polarization degree is also high. In the light having a wavelength of 550 nm, the transmittance of the polarizing plate of the present invention is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50%. desirable. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% for light having a wavelength of 550 nm.

[Liquid crystal display device]

The optical compensation film of this invention or the polarizing plate using this optical compensation film is used favorably for a liquid crystal display device, especially the OCB system liquid crystal display device, and the ECB system reflection type liquid crystal display device.

The transmissive liquid crystal display device consists of a liquid crystal cell and two polarizing plates arrange | positioned at both sides. The liquid crystal cell carries a liquid crystal between two electrode substrates.

One optical compensation film is arrange | positioned between a liquid crystal cell and the polarizing plate of one side, or two sheets are arranged between a liquid crystal cell and both polarizing plates. When an optical compensation film is used as a protective film of a polarizing plate, since a polarizing plate also functions as an optical compensation film, it is preferable at the point of thinness and weight reduction of a liquid crystal display device.

The liquid crystal cell may be Vertically Aligned (VA) mode, OCB mode, In-plane Switching (IPS) mode, or Twist Nematic (TN) mode.

In the liquid crystal cell of VA mode, rod-shaped liquid crystalline molecules are oriented substantially vertically when voltage is not applied.

In the liquid crystal cell of VA mode, (1) the liquid crystal cell of narrow VA mode which aligns rod-shaped liquid crystalline molecules substantially vertically when no voltage is applied, and substantially horizontally when voltage is applied (JP-A-2). In addition to (176), (2) a liquid crystal cell (of MVA mode) (SID97, Digest of tech.Papers (preliminary) 28 (1997) 845 description), which multidomains VA mode for viewing angle enlargement, (3) Liquid crystal cell of mode (n-ASM mode) in which rod-shaped liquid crystalline molecules are substantially vertically aligned when no voltage is applied and torsional multidomain alignment when voltage is applied (Preliminaries 58-59 (1998) Substrate) and (4) a liquid crystal cell of SURVAIVAL mode (presented by LCD International 98).

The liquid crystal cell of OCB mode is a liquid crystal cell of bend alignment mode that orients rod-like liquid crystalline molecules (symmetrically) in substantially opposite directions at the top and bottom of the liquid crystal cell. A liquid crystal display device using a liquid crystal cell in a bend alignment mode is disclosed in each of the specifications of US Pat. No. 4,458,525 and 5410422. Since the rod-like liquid crystalline molecules are symmetrically oriented at the top and bottom of the liquid crystal cell, the liquid crystal cell in the bend alignment mode has a magneto-optical compensation function.

Therefore, this liquid crystal mode is also called OCB (Optically Compensatory Bend) liquid crystal mode. The liquid crystal display of the bend alignment mode has an advantage that the response speed is high.

In the liquid crystal cell of TN mode, when a voltage is not applied, rod-shaped liquid crystalline molecules are substantially horizontally oriented, and are further twisted at 60-120 degree.

The liquid crystal cell of the TN mode is most often used as a color TFT liquid crystal display device, and many documents have been described.

The liquid crystal display device of the ECB (Electrically Controlled Birefringence) type | mold display system is the liquid crystal of the longest known structure using the liquid crystal cell of the horizontal orientation mode which orients rod-shaped liquid crystal molecules in the substantially same direction from the upper part and the lower part of a liquid crystal cell. It is a display device.

(Example)

An Example is given to the following and this invention is demonstrated to it further more concretely. Materials, reagents, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific example shown below.

Example 1

Optical Compensation Film for OBC

(Production of optical compensation film)

(Production of support)

The following composition was put into the mixing tank, it stirred while heating, each component was melt | dissolved, and the cellulose acetate solution was prepared.

(Cellulose acetate solution composition)

100 parts by mass of cellulose acetate having acetonitrile degree of 60.9%

Triphenyl phosphate (plasticizer) 7.8 parts by mass

Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass

300 parts by mass of methylene chloride (first solvent)

45 parts by mass of methanol (second solvent)

0.0009 parts by mass of dyes (360FP manufactured by Sumica Finechem Co., Ltd.)

16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were added to another mixing tank, and stirred while heating to prepare a retardation increasing agent solution.

36 parts by weight of the retardation synergist solution and 1.1 parts by weight of silica fine particles (Rirod, R972) were mixed with 464 parts by weight of the cellulose acetate solution having the above composition, followed by stirring sufficiently to prepare a dope. The addition amount of the retardation increasing agent was 5.0 mass parts with respect to 100 mass parts of cellulose acetate. Moreover, the addition amount of a silica fine particle was 0.15 mass part with respect to 100 mass parts of cellulose acetate.

(Formula 8)

Retardation synergist

The obtained dope was cast using a flexible machine having a band having a length of 2 m and a length of 65 m. After the film surface temperature on a band became 40 degreeC, it dried for 1 minute, peeled off, and it extended | stretched 28% in the width direction using the tenter with the drying air of 140 degreeC. Thereafter, the resultant was dried for 20 minutes in a drying air of 135 ° C to prepare a support (PK-1) having a residual solvent amount of 0.3% by mass.

The width | variety of the obtained support body (PK-1) was 1340 mm, and thickness was 92 micrometers. It was 38 nm when the retardation value (Re) in wavelength 590nm was measured using the ellipsometer (M-150, Nippon spectrometer). Moreover, it was 175 nm as a result of measuring the retardation value (Rth) in wavelength 590nm.

10 N / m2 of 1.0 N potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol = 69.2 parts by mass / 15 parts by mass / 15.8 parts by mass) was applied to the band surface side of the produced support body (PK-1). After holding for about 30 seconds in the state of about 40 degreeC, the alkaline liquid was extract | collected and it wash | cleaned with pure water and the water droplet was removed by air knife. Then, it dried for 15 second at 100 degreeC. It was 42 degrees when the contact angle with respect to the pure water of this PK-1 was calculated | required.

(Production of alignment film)

On this PK-1 (alkali-treated surface), the alignment film coating liquid of the following composition was apply | coated 28 ml / m <2> with the wire bar coater of # 16. The alignment film was produced by drying for 60 second by 60 degreeC warm air and 150 second by 90 degreeC warm air.

(Orientation film coating liquid composition)

10 parts by mass of the following modified polyvinyl alcohol

371 parts by mass of water

119 parts by mass of methanol

Glutalaldehyde (crosslinking agent) 0.5 parts by mass

Citrate ester (Sankyo Chemicals AS3) 0.35 parts by mass

Formula 9

Modified polyvinyl alcohol

(Rubbing treatment)

PK-1 was conveyed at a speed of 20 m / min, a rubbing roll (300 mm diameter) was set so as to be rubbed at 45 ° with respect to the longitudinal direction, and rotated at 650 rpm to give a rubbing treatment to the alignment film mounting surface of PK-1. . The contact length of the rubbing roll and PK-1 was set to be 18 mm.

(Formation of Optically Anisotropic Layer)

41.01 Kg of the following discotic liquid crystal compounds, ethylene oxide modified trimethylolpropane triacrylate (V # 360, Osaka Organic Chemical Co., Ltd.) 4.06 Kg, cellulose acetate butyrate (CAB 531-1, Eastman Chemical Co., Ltd. product) ) 0.35 Kg, photopolymerization initiator (Irgacure 907, manufactured by Chiba Co., Ltd.) 1.35 Kg, sensitizer (Kayacure DETX, Nippon Gunpowder Co., Ltd.) 0.45 Kg, citric acid ester (Sankyo Chemicals AS3) 0.45 Kg of 102 Kg 0.1 Kg of a fluoroaliphatic group containing copolymer (Megapak F780, Dainippon Ink Co., Ltd. product) was added to the coating liquid melt | dissolved in methyl ethyl ketone, and the wire bar of # 3.0 is 391 rotationally the same as the conveyance direction of a film. It rotated in the direction and apply | coated continuously to the orientation film surface of PK-1 conveyed at 20 m / min.

Formula 10

Discotic liquid crystal compound

In the step of continuously warming from room temperature to 100 ° C, the solvent is dried and then the film surface air velocity of the discotic liquid crystal compound layer is set to 2.5 m / sec in parallel to the conveyance direction of the film in a 130 ° C drying zone, and Heating for 90 seconds to orient the discotic liquid crystal compound. Next, in the state which conveyed to the drying zone of 40 degreeC, and the surface temperature of a film is about 60 degreeC, the ultraviolet-ray of illuminance 600mW is irradiated for 4 second with an ultraviolet irradiation device (ultraviolet lamp: output 160W / cm, emission length 1.6m). And the crosslinking reaction was advanced and the discotic liquid crystal compound was fixed in the orientation. Then, the 60 degreeC zone was passed through for about 1 minute, it was left to cool to room temperature, it wound up to cylindrical shape, and it was set as roll shape. In this way, a roll-shaped optical compensation film (KH-1) was produced.

The liquid crystal transition temperature of the said discotic liquid crystal compound was 115 degreeC, the film surface temperature of the discotic liquid crystal compound layer in the 130 degreeC dry zone was 127 degreeC, and the viscosity of this layer at this temperature was 695cp. The viscosity measured the liquid crystal layer (solvent removed) of the composition ratio similar to the layer with the heating type E viscometer.

A part of produced roll-shaped optical compensation film (KH-1) was cut out, and was used as a sample, and the optical characteristic was measured. The Re retardation value of the optically anisotropic layer measured at the wavelength of 546 nm was 31 nm. Moreover, the angle (tilt angle) of the disk surface and support body surface of the discotic liquid crystal compound in an optically anisotropic layer was changed continuously in the depth direction of the layer, and was an average of 28 degrees. Moreover, only the optically anisotropic layer was peeled from the sample and the average direction of the molecular symmetry axis of the optically anisotropic layer was measured, and it was 45 degrees with respect to the longitudinal direction of the optical compensation film (KH-1).

Moreover, when the polarizing plate was made into cross nicol arrangement | positioning, and the deviation of the obtained optical compensation film was observed, even if it saw from the direction which inclined to 60 degrees from the front and a normal line, the deviation was not detected.

In addition, the thickness of the discotic liquid crystal layer was 1.28 micrometers measured by the film thickness sensor Z5FM-200 by OMRON Corporation.

Comparative Example 1

In the same manner as in Example 1, rubbing finished alignment films were prepared on the support.

(Formation of Optically Anisotropic Layer)

The coating liquid similar to Example 1 was produced on this alignment film, and the wire bar of # 3.4 was rotated in the same direction as the conveyance direction of a film by 391 rotation, and it apply | coated continuously to the orientation film surface of PK-1 conveyed at 20 m / min. It was.

In the step of continuously warming from room temperature to 100 ° C, the solvent is dried and then the film surface air velocity of the discotic liquid crystal compound layer is set to 2.5 m / sec in parallel to the conveyance direction of the film in a 130 ° C drying zone, and Heating for 90 seconds to orient the discotic liquid crystal compound. Next, it is conveyed to the drying zone of 80 degreeC, and the ultraviolet-ray of illuminance 600mW is irradiated for 4 second with the ultraviolet irradiation device (ultraviolet lamp: output 160W / cm, light emission length 1.6m) in the state which the surface temperature of a film is about 120 degreeC. The crosslinking reaction was advanced to fix the discotic liquid crystal compound in the orientation. Then, it was left to cool to room temperature, it wound up to cylindrical shape, and it was set as roll shape. In this way, a roll-shaped optical compensation film (KH-H1) was produced.

The film surface temperature of the discotic liquid crystal compound layer in the said 130 degreeC dry zone was 127 degreeC.

A part of produced roll-shaped optical compensation film (KH-H1) was cut out, and was used as a sample, and the optical characteristic was measured. That is, the optical incidence angle dependence of Re of the film produced using the automatic birefringence meter (KOBRA-21ADH, Oji Measurement Instruments Co., Ltd.) was measured, and only the optically anisotropic layer was subtracted by subtracting the contribution of the support measured in advance. The optical retardation value of the optically anisotropic layer measured at the wavelength of 546 nm was 33 nm as a result of calculating the optical characteristic of the. Moreover, the angle (tilt angle) of the disk surface and support body surface of the discotic liquid crystal compound in an optically anisotropic layer was changed continuously in the depth direction of a layer, and was an average of 29 degrees. Moreover, only the optically anisotropic layer was peeled from the sample and the average direction of the molecular symmetry axis of the optically anisotropic layer was measured, and it was 45 degrees with respect to the longitudinal direction of the optical compensation film (KH-H1).

In addition, as a result of observing the deviation of the optical compensation film obtained by setting the polarizing plate to cross nicol, the deviation was not recognized from the front side, but when viewed from the direction inclined to 70 ° from the normal line, very thin optical deviation (film conveyance direction) Detected.

Moreover, the thickness of the discotic liquid crystal layer was 1.45 micrometers measured by the film thickness sensor Z5FM-200 by Omuron.

In addition, in this specification, Re ((lambda)) and Rth ((lambda)) represent the in-plane retardation in the wavelength (lambda), and the retardation of the thickness direction, respectively. Re (λ) is measured by injecting light having a wavelength of λ nm into the film normal line direction in KOBRA 21ADH (manufactured by Oji Metering Instruments Co., Ltd.). Rth (λ) is a light having a wavelength (λ) nm from a direction inclined at + 40 ° with respect to the film normal direction using the Re (λ) and the in-plane slow axis (determined by KOBRA 21ADH) as the inclination axis (rotation axis). The total retardation value measured by injecting the light and the retardation value measured by injecting light having a wavelength (λ) nm from a direction inclined at -40 ° to the film normal direction using the in-plane slow axis as the inclination axis (rotation axis). KOBRA 21ADH is calculated based on the retardation value measured in three directions, the assumption of the average refractive index, and the input film thickness value. Here, the hypothesized value of the average refractive index may be a polymer handbook (JOHN WILEY & SONS, INC) and values of catalogs of various optical films. What is not known about the average refractive index can be measured with an Abbe refractometer.

The value of the average refractive index of a main optical film is illustrated below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59). KOBRA 21ADH calculates nx, ny, and nz by inputting the assumption value and film thickness of these average refractive indices. From the calculated nx, ny and nz, Nz = (nx-nz) / (nx-ny) is further calculated.

Comparative Example 2

In the same manner as in Example 1, rubbing finished alignment films were prepared on the support.

(Formation of Optically Anisotropic Layer)

The coating liquid similar to Example 1 was produced on this alignment film, and the wire bar of # 3.0 was rotated in the same direction as the conveyance direction of a film by 391 rotation, and it apply | coated continuously to the orientation film surface of PK-1 conveyed at 20 m / min. It was.

In the step of continuously warming from room temperature to 100 ° C, the solvent is dried and then the film surface air velocity of the discotic liquid crystal compound layer is set to 2.5 m / sec in parallel to the conveyance direction of the film in a 130 ° C drying zone, and Heating for 90 seconds to orient the discotic liquid crystal compound. Next, it is conveyed to the dry zone of 40 degreeC, and the ultraviolet-ray 600mW of irradiance is irradiated for 4 second with the ultraviolet irradiation device (ultraviolet lamp: output 160W / cm, light emission length 1.6m) in the state which the surface temperature of a film is about 60 degreeC. And the crosslinking reaction was advanced, the discotic liquid crystal compound was fixed in the orientation, it was left to cool to room temperature, it wound up to cylindrical shape, and it was set as roll shape. In this way, a roll-shaped optical compensation film (KH-H2) was produced.

A part of produced roll-shaped optical compensation film (KH-H2) was cut out, and was used as a sample, and the optical characteristic was measured. The Re retardation value of the optically anisotropic layer measured at the wavelength of 546 nm was 31 nm. Moreover, the angle (tilt angle) of the disk surface and support body surface of the discotic liquid crystal compound in an optically anisotropic layer was changed continuously in the depth direction of the layer, and was an average of 28 degrees. Moreover, only the optically anisotropic layer was peeled from the sample and the average direction of the molecular symmetry axis of the optically anisotropic layer was measured, and it was 45 degrees with respect to the longitudinal direction of the optical compensation film (KH-H2).

In addition, when the polarizing plate was made into cross nicol arrangement | positioning, and the deviation of the obtained optical compensation film was observed, even if it saw from the direction which inclined to 60 degrees from the front and a normal line, the deviation was not inspected. In addition, the thickness of the discotic liquid crystal layer was 1.28 micrometers measured by the film thickness sensor Z5FM-200 by OMRON Corporation.

Example 2

Optical Compensation Film for IPS

(Film Production of Cellulose Acylate Film)

The cellulose acylate of acetyl substitution degree 2.785 (acetyl substitution degree 0.910 in 6 positions) was prepared. This added sulfuric acid (7.8 mass parts with respect to 100 mass parts of cellulose) as a catalyst, carboxylic acid was added, and the acylation reaction was performed at 40 degreeC. Thereafter, the total substitution degree and the 6-position substitution degree were adjusted by adjusting the sulfuric acid catalyst amount, water content, and aging time. Aging temperature was performed at 40 degreeC. In addition, the low molecular weight component of this cellulose acylate was removed by washing with acetone.

Dope preparation

11.7 parts by mass of a plasticizer (2: 1 mixture of triphenylphosphate and biphenyldiphenylphosphate), 6.5 parts by mass of a retardation expression agent having the following structure, a mixed solvent, dichloromethane / methanol (87/13) (Mass part) was added while stirring so that the mass concentration of solid content might be 19 mass%, and it heated and stirred, and melt | dissolved. At this time, 0.05 parts by mass of fine particles [silicon dioxide (primary particle diameter: 20 nm, Mohs hardness: about 7)] and UV absorber B (manufactured by TINUVIN327 Chiba Specialty Chemicals) were respectively 0.375 parts by mass based on 100 parts by mass of cellulose acylate. 0.75 mass part of ultraviolet absorbers C (made by TINUVIN328 Chiba Specialty Chemicals) were thrown in, and it stirred, heating. The addition ratio of a plasticizer and a retardation expression agent is a mass part when the amount of cellulose acylate is 100 mass parts. PK-2 was produced from the dope thus formed by the following method.

Retardation expression agent

Formula 11

(softness)

The dope described above was cast using a band softener. The film which peeled off from the band at 25-35 mass% of residual solvent was extended | stretched in the width direction at the elongation rate of 15% using the tenter, and the cellulose acylate film was produced. In a tenter, it extended | stretched in the width direction, heating and drying with hot air, and about 5% was contracted, and after that, it shifted from tenter conveyance to roll conveyance, dried further, and nerked and wound up.

The width | variety of the obtained support body (PK-2) was 1340 mm, and thickness was 80 micrometers. It was 63 nm when the retardation value (Re) in wavelength 590nm was measured using the ellipsometer (M-150, Nippon spectrometer). Moreover, it was 223 nm as a result of measuring the retardation value (Rth) in wavelength 590nm.

10 kPa / m <2> of 1.0N potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol = 69.2 mass part / 15 mass part / 15.8 mass part) was apply | coated to the band surface side of the said cellulose acylate film (PK-2). Then, after holding at about 40 ° C. for 30 seconds, the alkaline liquid was collected, washed with pure water, and water droplets were removed with an air knife. Then, it dried for 15 second at 100 degreeC.

It was 42 degrees when the contact angle with respect to the pure water of the alkali treatment surface was measured.

(Formation of alignment film)

A commercially available vertical alignment film (JALS-204R, manufactured by Nippon Synthetic Rubber Co., Ltd.) on the cellulose acylate film (alkali treatment surface) was diluted 1: 1 with methyl ethyl ketone, and then 2.4 ml / m 2 with a wire bar coater. Applied. It was dried for 120 seconds with a warm air of 120 ℃.

Next, the following rod-shaped liquid crystalline compound 3.8g, photoinitiator (Irgacure 907, Chiba Co., Ltd. product) 0.06g, sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd. product) 0.02g, the following air interface side vertical orientation The solution which melt | dissolved the 0.002g in 9.2g methyl ethyl ketone was prepared. This solution was apply | coated with the wire bar of # 5.2 to the orientation film side of the film in which the said orientation film was formed, respectively. This was attached to a metal mold and heated for 2 minutes in a 100 degreeC thermostat, and the rod-like liquid crystalline compound was orientated. Moreover, the liquid crystal transition temperature of the rod-like liquid crystalline compound was 80 degreeC. Next, UV irradiation was carried out at 30 ° C. with a 120 W / cm high-pressure mercury lamp for 20 seconds to crosslink the rod-like liquid crystalline compound, and after that, heating was performed for 70 ° C./30 seconds, followed by cooling to room temperature to produce an optically anisotropic layer. In this way, an optical compensation film (KH-2) was produced.

It was 495cp when the viscosity of the optically anisotropic layer was measured at the film surface temperature of 90 degreeC. Viscosity is the result of having measured the liquid crystal layer (solvent removed) of the same composition as an optically anisotropic layer with the heating type E-type viscometer.

The optical incident angle dependence of Re of the optical compensation film (KH-2) produced using the automatic birefringence meter (KOBRA-21ADH, Oji Measurement Instruments Co., Ltd.) was measured, and the contribution of the support measured beforehand was subtracted. As a result of calculating the optical properties of only the optically anisotropic layer, the Re-retardation value of the optically anisotropic layer measured at the wavelength of 546 nm was 0 nm and Rth was -260 nm, confirming that the rod-shaped liquid crystals were almost vertically aligned. It was.

Moreover, when the polarizing plate was made into cross nicol arrangement | positioning, and the deviation of the obtained optical compensation film was observed, even if it saw from the direction which inclined to 60 degrees from the front and a normal line, the deviation was not detected.

Moreover, the thickness of the discotic liquid crystal layer was 2.07 micrometers measured by the film thickness sensor Z5FM-200 by OMRON Corporation.

(Formula 12)

Rod-shaped liquid crystal compound

(Formula 13)

Air interface side vertical alignment agent:

Exemplary compound (II-4) described in Japanese Patent Application No. 2003-119959

Comparative Example 3

In the same manner as in Example 2, the coating liquid for forming a rod-like liquid crystal layer was adjusted, and this solution was applied to the alignment film side of the film on which the alignment film was formed, respectively using a wire bar of # 5.2. This was attached to a metal mold and heated for 2 minutes in a 100 degreeC thermostat, and the rod-like liquid crystalline compound was orientated. Next, UV irradiation was performed at 30 ° C. with a 120 W / cm high-pressure mercury lamp for 20 seconds to crosslink the rod-like liquid crystalline compound, and allowed to cool to room temperature to produce an optically anisotropic layer.

Moreover, when the polarizing plate was made into cross nicol arrangement | positioning, and the deviation of the obtained optical compensation film was observed, even if it saw from the direction which inclined to 60 degrees from the front and a normal line, the deviation was not detected.

Moreover, the thickness of the discotic liquid crystal layer was 2.07 micrometers measured by the film thickness sensor Z5FM-200 by OMRON Corporation.

Example 3

(Production of polarizing plate)

PVA film (thickness 80 µm, width 2500 mm) having an average degree of polymerization of 1700 and a degree of saponification of 99.5 mol% was longitudinally uniaxially stretched eight times in hot water at 40 ° C, and intact in an aqueous solution of 0.2 g / l iodine and 60 g / l potassium iodide as it is. It was immersed for 5 minutes at ° C, and then immersed in an aqueous solution of 100 g / l boric acid and 30 g / l potassium iodide. At this time, the film width was 1300 mm and the thickness was 17 µm.

Furthermore, after immersing this film in 20 degreeC for 10 second in the water washing layer, it is immersed in 30-degreeC for 15 second in the aqueous solution of 0.1 g / l of iodine and 20 g / l of potassium iodide, and this film is dried at room temperature for 24 hours, and is iodine type Polarizer (HF-1) was obtained.

The KH-1 (optical compensation film) produced in Example 1 using the polyvinyl alcohol-type adhesive agent was affixed on the one side of the polarizer (HF-1) in the support body (PK-1) surface. Moreover, the saponification process was performed to the triacetyl cellulose film (TD-80U: Fuji Photographic Film Co., Ltd. product) of thickness 80micrometer, and adhered to the opposite side of the polarizer using the polyvinyl alcohol-type adhesive agent.

It was arrange | positioned so that the longitudinal direction of a polarizer and the longitudinal direction of the support body (PK-1), and also the longitudinal direction of a commercially available triacetyl cellulose film may become parallel. Thus, the polarizing plate (HB-1BR) was produced.

Moreover, the KH-1 (optical compensation film) produced in Example 1 using the polyvinyl alcohol-type adhesive agent was affixed on the one side of the polarizer (HF-1) in the support body (PK-1) surface. Further, a film with an antireflection function (Fuji Film CV Clear View UA: manufactured by Fuji Photo Film Co., Ltd.) was subjected to saponification, and was attached to the opposite side of the polarizer using a polyvinyl alcohol-based adhesive.

It was arrange | positioned so that the longitudinal direction of the polarizer and the longitudinal direction of the support body (PK-1), and also the longitudinal direction of the film with a commercially available antireflection function may become parallel. Thus, the polarizing plate (HB-1BF) was produced.

[Comparative Examples 4 and 5]

In Example 3, instead of the optical compensation film KH-1, using the KH-H1 produced in Comparative Example 1, a polarizing plate (HB-H1BR), (HB-H1BF) was produced, and the optical compensation film KH- Instead of 1, KH-H2 produced in Comparative Example 2 was used to produce polarizing plates (HB-H2BR) and (HB-H2BF).

Example 4

<Production of Polarizing Plate Protective Film 1>

The following composition was put into the mixing tank, it stirred while heating, each component was melt | dissolved, and the cellulose acetate solution A was prepared.

<Cellulose Acetate Solution A Composition>

100 parts by mass of cellulose acetate having a degree of substitution of 2.86.

Triphenylphosphate (plasticizer) 7.8 parts by mass

Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass

300 parts by mass of methylene chloride (first solvent)

54 parts by mass of methanol (second solvent)

11 parts by mass of 1-butanol

The following composition was put into the other mixing tank, it stirred while heating, each component was melt | dissolved, and the additive solution B-1 was prepared.

<Additive solution B-1 composition>

80 parts by mass of methylene chloride

20 parts by mass of methanol

40 parts by mass of the following optically anisotropic reducing agent

(Formula 14)

40 mass parts of additive solution B-1 was added to 477 mass parts of cellulose acetate solution A, and it fully stirred, and dope was prepared. The dope was cast on a drum cooled from 0 ° C. to 0 ° C. Peel off at the outside of 70 mass% of solvent content rate, The both ends of the width direction of a film are fixed with a pin tenter (the pin tenter as described in FIG. 3 of Unexamined-Japanese-Patent No. 4-1009), and a solvent content rate is 3-5 mass%. It dried while maintaining the space | interval which the elongation of a horizontal direction (direction perpendicular | vertical to a machine direction) becomes 3% in a state. Then, it conveyed between rolls of a heat processing apparatus, and further dried, and produced the polarizing plate protective film 1 of thickness 80micrometer.

As a result of measuring the optical incidence dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd.) and calculating the optical characteristics, it can be confirmed that Re is 1 nm and Rth is 6 nm. (Λ = 590 nm).

(Production of polarizing plate)

The above-mentioned HF-1 was used as a polarizer.

The optical compensation film (KH-2) was attached so that the transparent support surface might be a polarizer side using polyvinyl alcohol-type adhesive agent. In addition, a saponification process was performed to the antireflection film (Fuji Film CV Clear View UA, Fuji Photo Film Co., Ltd. product), and it adhered to the opposite side of the polarizer using a polyvinyl alcohol-type adhesive agent.

The longitudinal direction of the polarizer, the longitudinal direction of the transparent support, and the longitudinal direction of the antireflection film were all arranged in parallel. Thus, the polarizing plate (HB-2BF) was produced.

Moreover, after saponifying the polarizing plate protective film 1, it adhered to one side of polarizer HF-1 using the polyvinyl alcohol-type adhesive agent. In addition, a commercially available triacetyl cellulose film (TD-80U: manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 µm was subjected to saponification treatment and adhered to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive (HB-2BR). ). The longitudinal direction of the polarizer, the longitudinal direction of the polarizing plate protective film 1, and the longitudinal direction of the commercially available triacetyl cellulose film were arranged so that all were parallel.

Single plate transmittance TT of 380 nm-780 nm in 25 degreeC 60% RH of polarizing plate HB-2BR, parallel transmittance PT, and orthogonal transmittance CT of the polarizing plate HB-2BR were measured using the spectrophotometer (UV3100PC), and the average value of 400-700 nm, And as a result of having calculated | required polarization degree P, TT was 40.8-44.7, PT was 34-38.8, CT was 1.0 or less, and P was 99.98-99.99. Moreover, the orthogonal transmittance CT ( ₃₈₀ ), CT ( ₄₁₀ ), and CT ( ₇₀₀ ) in wavelength _380nm , _410nm , 700nm were 1.0 or less, 0.5 or less, 0.3 or less, respectively. Further, in the polarizer durability test at 60 ° C 95% RH 500 hours, all of them were in the range of -0.1≤ΔCT≤0.2, -2.0≤ΔP≤0, and at 60 ℃ 90% RH, -0.05≤ΔCT≤0.15, -1.5≤ΔP ≤ 0.

Comparative Example 6

In Example 4, the polarizing plates (HB-H3BR) and (HB-H3BF) were produced using KH-H3 produced by the comparative example 3 instead of the optical compensation film KH-2.

(Evaluation of reworkability)

The polarizing plates obtained in Examples 3 and 4 and Comparative Examples 4, 5 and 6 were stuck on the glass surface, and reworkability was evaluated. Specifically, the polarizing plates obtained in Examples 3 and 4 and Comparative Examples 4, 5 and 6 were attached via an adhesive such that the optical compensation film was on the glass surface side, and aged at 50 ° C. and 5 atmospheres for 6 hours.

After completion of aging, the polarizing plate was peeled from the glass surface under the condition of 25 ° C and 60% RH. The number of sheets remaining without peeling a part of the member of the polarizing plate on the glass surface was investigated. The results are shown in Table 1.

Polarizer Trial The number of sheets remaining after peeling Example 3 100 0 Example 4 100 0 Comparative Example 4 100 0 Comparative Example 5 100 20 Comparative Example 6 100 50

Note) In each example, a plurality of polarizing plates were produced, respectively, and any polarizing plate also resulted in the results shown in Table 1 above.

Example 5

(Production of bend alignment liquid crystal cell)

A polyimide film was formed as an alignment film on two glass substrates with an ITO electrode, and the rubbing process was performed to the alignment film. The obtained two glass substrates were made to face each other by the arrangement which rubbing direction becomes parallel, and the cell gap was set to 4.5 micrometers. The liquid crystal compound (ZLI1132, Merck Co., Ltd.) whose (DELTA) n is 0.1396 was injected into the cell gap, and the bend orientation liquid crystal cell was produced. The size of the liquid crystal cell was 20 inches.

The polarizing plate (HB-1BF) produced in Example 3 was attached to the visual recognition side, and the polarizing plate (HB-1BR) was attached to the backlight side so that the produced bend orientation cell might be interposed. The optically anisotropic layer of the elliptically polarizing plate faced the cell substrate, and was disposed such that the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing it were antiparallel.

A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. It was set as the normally white mode of white display 2V and black display 5V. The viewing angle was measured in eight steps from black display (L1) to white display (L8) using a measuring instrument (EZ-Contrast160D, manufactured by ELDIM) with the ratio of transmittance (white display / black display) as the contrast ratio. In addition, front contrast (CR: luminance of white display / luminance of black display) was obtained. The results are shown in Table 2.

Polarizing Plate Used for Liquid Crystal Cell Viewing angle ^* Front CR Prize Ha Right and left Example 3 80 ° 80 ° 80 ° 400

* Contrast ratio 10 or more and no black level inversion (inversion between L1 and L2)

(Evaluation of deviation in panel)

The liquid crystal display of Example 5 was adjusted to the front halftone, and the deviation was evaluated. No deviation was observed in either direction.

Example 6

<Production of IPS Mode Liquid Crystal Cell>

As shown in FIG. 1 on one glass substrate, electrodes (2 and 3 in FIG. 1) are arrange | positioned so that the distance between adjacent electrodes may be set to 20 micrometers, a polyimide film is formed as an orientation film on it, and a rubbing process is performed. It was. The rubbing process was performed in the direction 4 shown in FIG. A polyimide film was formed on one surface of one glass substrate prepared separately, and the rubbing process was performed to set it as an orientation film. The two glass substrates are arranged so that the alignment films are opposed to each other so that the gap (gap) d of the substrates is 3.9 µm, and the two glass substrates are stacked so that the rubbing directions of the two glass substrates are parallel to each other, and then the refractive index anisotropy (Δn) is 0.0769 and the dielectric constant. The nematic liquid crystal composition whose anisotropy ((DELTA) epsilon) is positive 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

(Production of liquid crystal display device)

The polarizing plate (HB-2BR) and the polarizing plate (HB-2BF) were affixed so that the produced cell might be interposed. Polarizing plate (HB-2BF) is a visual recognition side.

Adhesion is performed so that the slow axis of the cellulose acylate film is parallel to the rubbing direction of the liquid crystal cell on one side of the IPS mode liquid crystal cell produced above (that is, the slow axis of the cellulose acylate film The polarizing plate was attached so that the rod-like compound layer might be in the liquid crystal cell side.

Subsequently, it attached to the other side of this IPS mode liquid crystal cell 1 so that a polarizing plate protective film 1 side might become a liquid crystal cell side, and it arrange | positioned so that a cross nicol arrangement may be carried out with the polarizing plate 1, and the liquid crystal display device was produced. The leakage light of the liquid crystal display device thus produced was measured.

The leakage light when observed from the left oblique direction 60 ° was 0.1% or less.

In addition, the leakage light when the optical compensation film was not used was 0.6%.

Moreover, the visual characteristics in the state left to stand at 25 degreeC 80% RH and 25 degreeC 10% RH for 1 week were investigated.

The results are shown in Table 3.

Optical compensation film Front contrast Viewing Angle (Contrast> 10) 25 ℃ 80% 25 ℃ 10% Up / down Right and left KH-2 480 80 ° / 80 ° 80 ° / 80 ° clear clear none 460 80 ° / 80 ° 80 ° / 80 ° Invert left and right gradations Summer gradation inversion

According to the present invention, it is possible to stably and continuously produce an optical compensation film having an excellent optical compensation function for a liquid crystal display device, especially an OCB type liquid crystal display device having a fast response speed and moving picture aptitude, and small optical deviation. The optical compensation film can be easily produced in the form of a roll.

Moreover, according to this invention, the polarizing plate which has a polarizing function, has the outstanding optical compensation function with respect to a liquid crystal display device, especially an OCB system liquid crystal display device, and has a small optical deviation can be provided. By the polarizing plate of this invention, a liquid crystal display device can be thin and lightweight.

Moreover, according to this invention, the liquid crystal display device which can display the image with a high display quality, especially the OCB system liquid crystal display device with fast response speed and moving image aptitude can be provided.

Claims (6)

Coating a coating liquid containing a polymerizable liquid crystal compound on the surface of the support or on the support to form a liquid crystal compound layer; Simultaneously or after drying the liquid crystal compound layer, orienting the liquid crystal compound at a temperature above the liquid crystal transition temperature, and fixing the orientation to form an optically anisotropic layer; And Fixing the alignment of the liquid crystal compound and then heating the optically anisotropic layer; As a manufacturing method of an optical compensation film having The heating temperature in the process of heating the said optically anisotropic layer is 40 degreeC-150 degreeC, and a heat time is 5 second-3000 second, The manufacturing method of the optical compensation film characterized by the above-mentioned. An optical compensation film having a support and an optically anisotropic layer formed by using a polymerizable liquid crystal compound on the support, wherein the optical compensation film is produced by the production method according to claim 1. The method of claim 2, The said polymeric liquid crystal compound is a discotic liquid crystal compound which has a polymeric group, The optical compensation film characterized by the above-mentioned. It has the optical compensation film and polarizing film of Claim 2 or 3, The polarizing plate characterized by the above-mentioned. The optical compensation film of Claim 2 or 3 was provided. The liquid crystal display device characterized by the above-mentioned. The method of claim 5, wherein A liquid crystal display device, wherein the display method is an OCB method, an ECB method, or an IPC method.

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