JPH09185068A - Production of liquid crystal oriented film material and manufacture of liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a liquid crystal oriented film material that attains the realization of a liquid crystal structure in which each of the minute domains of a liquid crystal is in an oriented states different from each other with a small number of process stages and also, widening of the visual field angle by using a material consisting of a mixture of a polyimide or polyimide precursor, a photo-crosslinking agent and a low-molecular weight compound having a long-chain alkyl group as the oriented film material. SOLUTION: In this production, a polyimide or polyimide precursor, a photo-crosslinking agent and a low-molecular weight compound having a long-chain alkyl group are mixed together to produce a liquid crystal oriented film material. The resulting oriented film material is dissolved into an organic solvent such as N-methyl-2-pyrolidinone to obtain a solution and substrates 11 and 12 are coated with the solution and thereafter, the coating films are heated and dried to form films 31 and 32 to be oriented. Then, the objective oriented films which attain realization of the liquid crystal structure described above are formed from the films 31 and 32 by only adding an ultraviolet ray irradiation stage to the conventional process stages and only once performing rubbing treatment to each of the substrates 11 and 12, without forming the structure of each of the films 31 and 32 into a partially two- layered structure so as to correspond to the minute domains of a liquid crystal. Thus, the production process of the oriented films can be facilitated and accordingly, the production cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film material suitable for an alignment film of a liquid crystal display panel and a method for manufacturing a liquid crystal display panel, and more particularly to a liquid crystal alignment film having a plane in which the alignment state of liquid crystal is different for each minute region. The present invention relates to a material and a method for manufacturing a liquid crystal display panel.

[0002]

2. Description of the Related Art Liquid crystal display panels are thin and lightweight and have low power consumption, and are now widely used. This liquid crystal display panel has a structure in which liquid crystal is injected between two upper and lower transparent substrates having electrodes, the voltage applied to the electrodes is controlled, and the orientation of the liquid crystal is changed by the action of an electric field. Display is performed by utilizing changes in optical properties.

A liquid crystal display panel uses a change in liquid crystal orientation due to the action of an electric field as its operating principle.
Uniformity and stability of liquid crystal alignment are considered to be particularly important.

Conventionally, a method of oblique vapor deposition of silicon oxide or rubbing of an organic polymer film has been used as a means for obtaining the uniformity of liquid crystal alignment. From the viewpoint of workability and cost, organic polymer is used. Membranes are the mainstream.

Among these organic polymer films, the polyimide film is particularly excellent in consideration of heat resistance and insulating properties.

As the polyimide film material, a polyimide-based polymer compound or a polyamic acid-based polymer compound is mainly used. Both are used as a solvent dissolved in a suitable solvent, but the former (polyimide-based polymer compound) is a polyimide-based polymer compound that is made soluble in the solvent by introducing a polar group, and after applying the solvent. , A solvent that evaporates a solvent by firing to form a polyimide film (soluble polyimide type), and the latter (polyamic acid-based polymer compound) is a polyamic acid-based polymer compound that is a precursor of polyimide. After applying a solvent, a dehydration reaction is caused by firing to imidize the polyamic acid to form a polyimide film (polyamic acid type).

In the most commonly used liquid crystal display panel of twisted nematic type (also referred to as "twisted nematic type"), liquid crystal is twisted and aligned in a spiral shape from one substrate to the other substrate. Therefore, the alignment of liquid crystal molecules near the surfaces of the alignment films on both substrates is substantially perpendicular to each other.

Liquid crystal molecules near the surface of the alignment film are pretilt with respect to each substrate.

The alignment direction and pretilt direction of the liquid crystal molecules near the surface of each substrate are determined according to the rubbing direction of the alignment films on both substrates, as described above.

In such a twisted nematic liquid crystal display panel, the transmittance of incident light can be controlled by controlling the voltage applied to the liquid crystal, and gradation display from the bright state to the dark state can be performed.

However, since the brightness of each gradation changes depending on the viewing direction of the screen, there is a problem that the viewing angle range in which the display can be accurately recognized is narrow. That is, when viewed from a certain direction, the entire display is whitish, and when viewed from the opposite direction, the entire display is blackened or gradation is inverted.

The viewing angle dependence of the liquid crystal display panel is due to the asymmetry of the alignment state of the liquid crystal.

The rising direction of liquid crystal molecules when a voltage is applied to the liquid crystal is determined by the pretilt direction.
Further, the rising angle of the liquid crystal molecules depends on the magnitude of the voltage applied to the electrodes, and the gradation display can be performed by controlling the magnitude of the voltage.

The movement of the liquid crystal molecules due to the applied voltage is small near the surfaces of both substrates and large in the intermediate region between both substrates.
Therefore, mainly of the liquid crystal molecules existing in the intermediate region of both substrates,
The rising angle with respect to the substrate contributes to the brightness of the display.

In a state where the liquid crystal molecules in this region stand up from the substrate at a certain angle, that is, in the halftone display state, when the liquid crystal display panel is observed from the rising direction of the liquid crystal molecules, the screen looks black, while When viewed from the opposite direction, it looks white.

In order to solve such a problem of viewing angle characteristics, for example, Japanese Patent Publication No. 58-43723 proposes a structure in which regions in which the alignment treatment directions of the alignment film are different from each other are formed at a fine pitch. There is. That is, the gazette states that
Alignment performance is imparted to the inner surface, and in a liquid crystal element in which a nematic liquid crystal is sandwiched between a pair of transparent electrode plates facing each other so that the alignment performance is substantially orthogonal to each other, the alignment performance on the liquid crystal plate surface can be visually observed. There has been proposed a liquid crystal element in which opposite pitches are applied alternately at a fine pitch that cannot be discriminated.

FIG. 5 shows the structure of a cross section of a conventional liquid crystal display panel based on the proposal of Japanese Patent Publication No. 58-43723. In FIG. 5, 11 and 12 are substrates, 20 is a liquid crystal,
Reference numerals 31 and 32 are alignment films, 71 is a pixel electrode, 72 is a common electrode, and 100 is a liquid crystal display panel.

Referring to FIG. 5, this conventional liquid crystal display panel has a structure in which the alignment treatment directions of the alignment film are different for each of the minute regions A and B. Therefore, minute areas A and B
Therefore, the rising directions of the liquid crystal molecules when a voltage is applied are different, and the observer recognizes the viewing angle characteristics of each minute region as averaged. As a result, the viewing angle characteristics are improved.

In order to form such regions having different alignment treatment directions on the same substrate, for example, a resist is applied on the alignment film which has been rubbed in one direction, and a predetermined shape is formed by a photolithography technique. Patterning,
It is necessary to perform a step of rubbing again in the direction opposite to the rubbing direction of the first time and then removing the resist. In this step, since the orientation direction is divided, two rubbing processes are required for one substrate.

Further, in order to solve the problem that many steps are required to perform the alignment process so that the alignment state of the liquid crystal is different for each minute region, both substrates are subjected to the rubbing process once to remove the liquid crystal. In order to realize a liquid crystal display device having two minute regions having different alignment states, for example, in Japanese Unexamined Patent Publication (Kokai) No. 5-210099, the alignment film is partially formed in a two-layer structure in accordance with a predetermined pattern, thereby providing the same structure. A liquid crystal display device has been proposed in which minute regions A and B having mutually different pretilt angles are formed on a substrate.
That is, according to the liquid crystal display device proposed in the publication,
There is no need to divide the orientation processing direction, and 1 per substrate
The same effect of improving the viewing angle characteristics can be obtained by rubbing once.

FIG. 6 shows a sectional structure of a liquid crystal display panel based on the above-mentioned Japanese Patent Laid-Open No. 5-210099.

Referring to FIG. 6, the alignment films 31 and 32 of both substrates 11 and 12 have a two-layer structure of a first alignment film layer 51 and a second alignment film layer 52.

In the alignment film 31 of the lower substrate 11, the alignment film layer 52 of the second layer is opened in the minute region B,
The first alignment film layer 51 is exposed, and in the minute area A, the second alignment film layer 52 is exposed.

Although the minute regions A and B have the same alignment direction and pretilt direction, the first alignment film layer 51 and the second alignment film layer 52 have different pretilt angles α ° and β, respectively. (°) (<α °), the lower substrate 11
In the vicinity of the surface of the alignment film 31, the pretilt angle in the minute region A is α ° and the pretilt angle in the minute region B is β °.

On the other hand, in the alignment film 32 of the upper substrate 12, in the minute region A, the second alignment film layer 52 is opened, and the first alignment film layer 51 is exposed. In the minute area B, the second alignment film layer is exposed. Therefore, near the surface of the alignment film on the upper substrate 12,
The pretilt angle in the minute area A is β °, and the pretilt angle in the minute area B is α °.

In the structure shown in FIG. 6, the alignment directions of the liquid crystal in both the minute regions A and B increase from the vicinity of the surface of the alignment film 31 of the lower substrate 11 to the vicinity of the surface of the alignment film 32 of the upper substrate 12. Twisted. Also, both substrates 1
The pretilt directions near the surface of Nos. 1 and 12 are opposite to each other, and the spray deformation is performed so that the angle with respect to the plane parallel to the substrate surface gradually changes between them. That is, the whole is in a splay type twisted nematic type alignment state.

When attention is paid to each of the minute regions A and B, the magnitudes of the pretilt angles of the liquid crystal molecules near the surfaces of the alignment films 32 and 31 of the upper and lower substrates 12 and 11 are different. In a liquid crystal display panel of splay orientation in which the magnitudes of the pretilt angles on the upper and lower substrates 12 and 11 are different, the liquid crystal rises in accordance with the pretilt direction having the larger pretilt angle when a voltage is applied.

That is, in the minute region A, according to the pretilt direction near the surface of the alignment film 31 of the lower substrate 11, in the minute region B, according to the pretilt direction near the surface of the alignment film 32 of the upper substrate 12. Stand up each.

As described above, the rising directions of the liquid crystal molecules at the time of voltage application are different between the minute regions A and B, and the viewing angle characteristics of the respective minute regions are averaged and recognized by the observer. That is, even with the structure according to the above-mentioned Japanese Patent Laid-Open No. 5-21099, it is possible to obtain the same effect as the structure according to the above-mentioned Japanese Patent Publication No. 58-43723.

Such a structure in which the magnitude of the pretilt angle is different for each minute region can be formed by a series of alignment treatment methods shown in FIG. 7 as a process sectional view.

FIG. 7A is a diagram showing a state in which the first alignment film layer 51 is formed on the pixel electrode 71.
7B is a diagram in which the second alignment film layer 52 is formed, and FIG. 7C is a diagram showing the second alignment film layer 52 according to the pattern formed by the resist material 40 by the photolithography technique.
FIG. 7D is a diagram showing a state where the resist pattern is partially removed, and FIG. 7D is a diagram showing a state where the resist pattern is peeled off.
(E) is a diagram schematically showing a state in which the rubbing process is performed by the rubbing roller 80.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 6-148641, only the alignment film on one substrate has a two-layer structure partially according to a predetermined pattern, and the magnitudes of the pretilt angles are mutually different in each of the minute regions A and B. A liquid crystal display panel has been proposed in which an alignment treatment is performed differently, and an alignment film on the other substrate is subjected to an alignment treatment so as to be uniformly pretilted as a structure including a single layer. FIG. 8 shows the above-mentioned JP-A-6-148641.
The structure of the cross section of the liquid crystal display panel based on the publication is shown.

Referring to FIG. 8, the alignment film 31 of the lower substrate 11 has the same structure as that of the liquid crystal display panel shown in FIG. 6 and has been subjected to the alignment treatment. Therefore, near the surface of the alignment film 31 of the lower substrate 11, the pretilt angle in the minute region A is α ° and the pretilt angle in the minute region B is β °.
It has become.

On the other hand, the alignment film 32 of the upper substrate 12 is composed of a single layer and is uniformly aligned. In the vicinity of the surface of the alignment film 32 of the upper substrate 12, the pretilt angle is γ °.
(Α °> γ °> β °).

In the structure shown in FIG. 8, as in the case of the liquid crystal display panel shown in FIG. 6, the liquid crystal 20 is in a splay type twisted nematic type alignment state as a whole. Focusing on each of the minute regions A and B, the size of the pretilt angle of the liquid crystal molecules near the surfaces of the alignment films 32 and 31 of the upper and lower substrates 12 and 11 is different. According to the pretilt direction in the vicinity of the surface of the alignment film 31 of the substrate 11, the micro region B rises in accordance with the pretilt direction in the vicinity of the surface of the alignment film 32 of the upper substrate 12.

As described above, the rising directions of the liquid crystal molecules when the voltage is applied are different in the minute areas A and B, and the observer recognizes the viewing angle characteristics of the respective minute areas as averaged. That is, even with the structure according to Japanese Patent Laid-Open No. 6-148641, the same effect as the structure according to Japanese Patent Laid-Open No. 5-21099 or the structure according to Japanese Patent Publication No. 58-43723 can be obtained.

[0037]

As described above, for the purpose of improving the viewing angle characteristics of a liquid crystal display panel, a liquid crystal in which an alignment film is subjected to an alignment treatment so that the alignment state of the liquid crystal is different for each minute region. In order to manufacture display panels,
As described above, it is necessary to form the finely patterned alignment film having the two-layer structure.

For this purpose, application of the first layer alignment film material,
Many steps are required such as application of the second layer alignment film material, formation of a predetermined resist pattern by photolithography, partial removal of the second layer alignment film layer according to the resist pattern, and resist stripping. There was a problem.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and realizes a structure in which the alignment state of the liquid crystal is different for each minute region with a smaller number of steps than that of the prior art, and is wide. An object of the present invention is to provide a liquid crystal display panel that achieves a wide viewing angle.

[0040]

In order to achieve the above object, a liquid crystal alignment film material according to the present invention comprises at least a polyimide or a polyimide precursor, a photocrosslinking agent, and a low molecular weight compound having a long chain alkyl group. It is characterized by being a mixture of.

This mixture is dissolved in an organic solvent such as N-methyl-2-pyrrolidinone, coated on a substrate, dried by heating and used.

In the liquid crystal alignment film material according to the present invention,
A compound having at least two azido groups can be used as the photocrosslinking agent, and a compound having an unsaturated bond such as a long-chain alkyl acrylate can be used as the low-molecular compound having a long-chain alkyl group.

Further, according to the present invention, the first and second opposing substrates (1) provided with alignment films (31, 32; see FIG. 1) are provided.
1, 12) and a nematic liquid crystal (20) in a splay type twisted nematic type alignment state inserted between substrates.
A method of manufacturing a liquid crystal display panel, wherein the alignment film of at least one of the substrates is subjected to an alignment treatment such that the magnitude of the pretilt angle of the liquid crystal in the vicinity of the alignment film surface is different for each minute region. ) A step of applying a liquid crystal alignment film material according to the present invention to at least one of the first and second opposing substrates to form a liquid crystal alignment film,
(b) a step of irradiating the liquid crystal alignment film with ultraviolet rays through a photomask having a predetermined pattern, (c) a step of baking the liquid crystal alignment film, and (d) a certain direction of the liquid crystal alignment film surface. A method of manufacturing a liquid crystal display panel, comprising: a rubbing treatment step; and a fine alignment area forming step.

Further, in the method for manufacturing a liquid crystal display panel according to the present invention, the liquid crystal in the vicinity of the surface of the alignment film is formed for each minute region in the alignment films (31, 32) of both the first and second substrates by the above steps. After the alignment treatment is performed so that the magnitudes of the pretilt angles are different from each other, a region having a large pretilt angle near the surface of the alignment film (31) of the first substrate is near the surface of the alignment film (32) of the second substrate. A region facing a region having a small pretilt angle and having a small pretilt angle in the vicinity of the surface of the alignment film (31) of the first substrate has a large pretilt angle in the vicinity of the surface of the alignment film (32) of the second substrate. It is characterized in that a step of superposing the first substrate (11) and the second substrate (12) is provided so as to face the region.

In the method for manufacturing a liquid crystal display panel of the present invention, of course, only the alignment film on one of the substrates (for example, the first
The alignment film 31 of the substrate 11 is subjected to an alignment treatment such that the size of the pretilt angle of the liquid crystal (20) near the surface of the alignment film is different for each minute region, and the alignment film of the other substrate (for example, the second substrate). The alignment film 32 of 12 is a liquid crystal (2
The alignment treatment may be performed so that the pretilt angle of 0) becomes uniform. In this case, the alignment film (31) of the first substrate (11)
Of the pretilt angle near the surface of the second substrate (12) is α °, the smaller one is β °, and the pretilt angle near the surface of the alignment film (32) of the second substrate (12) is γ °. In addition, it is also possible to configure so that the relationship α>γ> β holds. That is, it is possible to obtain a structure in which the alignment state of the liquid crystal is different for each minute region, and it is not necessary to partially form the alignment film to have a two-layer structure so as to correspond to the minute region. Therefore, cost reduction can be achieved.

[0046]

The principle and operation of the present invention will be described in detail below.

The liquid crystal alignment film material according to the present invention can be prepared very simply by mixing a polyimide or a polyimide precursor, a photocrosslinking agent, and a low molecular compound having a long-chain alkyl group. .

The liquid crystal alignment film material according to the present invention is dissolved in an organic solvent such as N-methyl-2-pyrrolidinone, coated on a substrate, heated and dried to form an alignment film, and then a predetermined pattern is formed. When the alignment film surface is irradiated with ultraviolet rays through a photomask and then the liquid crystal alignment film is baked,
In the region where the surface of the alignment film is not irradiated with ultraviolet rays according to the pattern of the photomask, a lower pretilt angle is exhibited when the liquid crystal is brought into contact with the surface, as compared with the region where ultraviolet rays are irradiated.

The mechanism causing such a phenomenon of different pretilt angles is not yet clear, but it can be inferred as follows. That is, after the liquid crystal alignment film material according to the present invention is applied to a substrate to form an alignment film, the alignment film surface is irradiated with ultraviolet rays through a photomask having a predetermined pattern, and then the liquid crystal alignment film is baked. If you do, in the area that was not exposed to ultraviolet light,
A low-molecular compound having a long-chain alkyl group evaporates because it is heated at a temperature considerably higher than its boiling point, but in the region irradiated with ultraviolet rays, the low-molecular compound having a long-chain alkyl group cross-links the photocrosslinking agent. It does not evaporate because it is chemically bonded to the polymer chains of the polyimide film material by the reaction.

When a large number of long-chain alkyl groups are present on the surface of the substrate, vertical alignment may occur, according to the literature (Frederic.J.Kahn, “O”).
rientation of liquid crystals by surface coupling
agents ”, Applied Physics Letters, Vol.22, No.8,
P. 386, 1973). Therefore, when the long-chain alkyl group component is present on the surface of the liquid crystal alignment film, the pretilt angle of the liquid crystal molecules becomes larger when the liquid crystal is brought into contact with the surface than when the long-chain alkyl group component is not present. According to the above method, the distribution density of the long-chain alkyl group component on the surface of the liquid crystal alignment film is treated so as to be different for each minute region, so that the liquid crystal molecules on the alignment film surface for each minute region are treated. It is considered that the pretilt angles could be made different.

In the present invention, the rubbing treatment is performed after irradiating the liquid crystal alignment film with ultraviolet rays and baking the liquid crystal alignment film,
You only have to do it once. That is, according to the present invention, by simply adding an ultraviolet irradiation step to the conventional manufacturing process,
Since the effect of widening the viewing angle can be obtained by only rubbing the substrate once, it is not necessary to partially form the liquid crystal alignment film into two layers. Therefore, the manufacturing process is facilitated and the cost can be reduced.

In the present invention, when a compound having at least two azido groups is used as the photocrosslinking agent, the terminal azido group having photosensitivity is decomposed by photoirradiation to produce a highly reactive nitrene, It becomes possible to efficiently fix a low-molecular compound having a long-chain alkyl group to the polymer chain of the polyimide film material, and the above-mentioned action is obtained.

As such a photo-crosslinking agent, in addition to 2,6-bis (4'-azidobenzal) 4-methylcyclohexanone shown in Chemical Formula 1, for example, 4,4 shown in Chemical Formula 2 is used.
-Diazidochalcone, 1,3-bis (4'-azidobenzal) -2-propanone shown in chemical formula 3, chemical formula 4
1,3-bis (4'-azidocinnamylidene)-
2-propanone, 4,4-diazidostilbene-2,2′-disulfonic acid represented by the chemical formula 5, 1 represented by the chemical formula 6
3-bis (4'-azidobenzal) -2-propanone-
2; 2-disulfonic acid, 2,6-bis (4'-azidobenzal) cyclohexanone-2; 2-
An azido group such as disulfonic acid, 2,6-bis (4'-azidobenzal) methylcyclohexanone-2 represented by Chemical Formula 8; 2-disulfonic acid, 2,6-bis (4'-azidobenzal) cyclohexanone represented by Chemical Formula 9 A compound having two groups can be used. Of course, a compound having three or more azide groups can be used as well.

[0054]

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[0059]

[Chemical 6]

[0060]

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[0061]

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[0062]

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In the present invention, when a compound having an unsaturated bond such as a long-chain alkyl acrylate or a long-chain alkyl methacrylate is used as the low-molecular compound having a long-chain alkyl group, photocrosslinking is used. It is possible to fix the alkyl group component with the agent extremely efficiently.

If the carbon number of the long-chain alkyl is too short, there is no effect of increasing the pretilt angle, the boiling point is low, and the solvent easily evaporates with the solvent. Therefore, the carbon number of the alkyl group is preferably 12 or more. . On the other hand, the carbon number of the long-chain alkyl is preferably 19 or less because the compatibility with the polyimide precursor is deteriorated when the carbon number is too long. As a low-molecular compound having such a long-chain alkyl group,
In addition to stearyl acrylate represented by Chemical Formula 10, for example, lauryl acrylate represented by Chemical Formula 11 and Chemical Formula 1
2 tridecyl acrylate, chemical formula 13 myristyl acrylate, chemical formula 14 pentadecyl acrylate, chemical formula 15 cetyl acrylate,
Heptadecyl acrylate represented by Chemical Formula 16, Chemical Formula 1
The nonadecyl acrylate shown in 7, the heptadecyl methacrylate shown in the chemical formula 18, the stearyl methacrylate shown in the chemical formula 19, the nonadecyl methacrylate shown in the chemical formula 20, and the like can be used.

[0065]

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[0074]

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[0075]

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Further, in the present invention, in order to secure a sufficient difference in pretilt angle between the exposed portion and the unexposed portion,
It is preferable to mix the photocrosslinking agent in the same amount as the polyimide film material and the low molecular weight compound having a long-chain alkyl group in a ratio of about 1/10 of the alignment film material.

The present invention is characterized in that the pretilt angle is increased by irradiation with ultraviolet rays. Therefore, the polyimide film material serving as the base is, by itself, characterized by a relatively low pretilt angle. Needless to say, it is preferable.

[0078]

Embodiments of the present invention will be described below.

[0079]

[Embodiment 1] 100 g of a polyimide varnish SE-1180 (0322) manufactured by Nissan Chemical Industries, Ltd. was added with a photo-crosslinking agent represented by Chemical Formula 1, that is, 2,6-bis (4'-azidobenzal) 4-methylcyclohexanone. 3 g (3% by weight), 0.3 g of a low-molecular compound having a long-chain alkyl group represented by Chemical Formula 10, that is, stearyl acrylate
(0.3% by weight) to adjust the liquid crystal alignment film material.

SE-1180 (0322) is a soluble polyimide type polyimide varnish containing a polyimide-based polymer compound as a main component (3% by weight), and has a pretilt angle of a liquid crystal alignment film formed by a usual method. Is
It is about 1 degree.

FIG. 1 shows a liquid crystal display panel 100 according to an embodiment of the present invention. In addition, polarizing plates (not shown) are arranged on both sides of the liquid crystal display panel 100 shown in FIG.

Referring to FIG. 1, the liquid crystal display panel 100 according to the present embodiment has a liquid crystal 20 enclosed between a pair of transparent substrates 11 and 12.

A pixel electrode 71 and an alignment film 31 are provided on the inner surface of the lower substrate 11. The pixel electrode 71 is connected to an active matrix circuit (not shown).

Inside the upper substrate 12, ITO (Indium
-Tin-Oxide) common electrode 72 is provided.
An alignment film 32 is provided on the above.

FIG. 2 schematically shows the substrate orientation treatment method in this embodiment in order. The alignment treatment method in this embodiment will be described below with reference to FIG. Note that FIG. 2 shows only the alignment treatment for the lower substrate 11 in FIG. 1, but the upper substrate 12 is also similarly subjected to the alignment treatment.

First, as shown in FIG. 2A, the substrate 11
The above-mentioned liquid crystal alignment film material is applied on the alignment film 31
To form

Next, as shown in FIG. 2B, the alignment film 3
1 is irradiated with ultraviolet rays in a nitrogen atmosphere through a photomask 60 having a predetermined pattern.

Then, the substrate 11 is put in an oven to 200
The alignment film 31 was fired by heating it at 1 ° C. for 1 hour, and was then rubbed in a fixed direction as shown in FIG. At that time, the rubbing treatment was performed by advancing the rubbing roller 80 wound with a rayon buff cloth while rotating on the alignment film 31.

As shown in FIG. 3, the rubbing directions of the substrates thus oriented are set so that the rubbing directions of the respective substrates 11 and 12 are substantially perpendicular to each other (the rubbing direction of the substrate 11 is indicated by a broken line arrow, The rubbing directions of the substrates 12 are indicated by solid arrows), and a counterclockwise nematic liquid crystal 20 to which a chiral agent is added is inserted between the substrates.

At this time, the exposed portion on the surface of the alignment film 31 and the unexposed portion on the surface of the alignment film 32 in the exposure process shown in FIG. Both substrates are superposed so that the portion and the photosensitive portion on the surface of the alignment film 32 face each other.

The liquid crystal 20 is subjected to the above-mentioned alignment treatment.
The substrates 11 and 12 are twisted and oriented by approximately 90 degrees.

In addition, the spray deformation is performed so that the pretilt direction with respect to the plane parallel to the substrate surface gradually changes from one substrate to the other substrate, and the pretilt directions near both substrate surfaces are opposite to each other. doing.
That is, the whole is in a splay type twisted nematic type alignment state.

In this liquid crystal display panel, the pretilt angles on the surfaces of both substrates were measured.

The measurement result of the pretilt angle is 10 at the photosensitive portion on the surface of the alignment film during the exposure process shown in FIG.
It was found that the pre-tilt angle was different, since the unexposed area was 1 degree.

As described above, in the present embodiment, FIG.
The alignment state of the liquid crystal 20 is different for each of the minute regions A and B shown in FIG. That is, in the minute area A, the lower substrate 11
The pretilt angle α near the surface of the upper substrate 12 is larger than the pretilt angle γ near the surface of the upper substrate 12, and in the minute region B, the pretilt angle γ near the surface of the upper substrate 12 is lower. It is larger than the pretilt angle β near the surface of the substrate 11.

When a voltage is applied, the minute area A,
For each B, it was confirmed that the liquid crystal rises according to the larger pretilt angle α or β of the surfaces of both substrates 11 and 12.

That is, in the minute area A, the rise occurs according to the pretilt direction near the surface of the lower substrate 11, and in the minute area B, the rise occurs according to the pretilt direction near the surface of the upper substrate 12.

As described above, the rising directions of the liquid crystal molecules when a voltage is applied are different between the minute regions A and B, and the asymmetrical viewing angle characteristics of the respective minute regions are averaged and recognized by the observer. In contrast, the display can be recognized in a wider viewing angle range as compared with the above-described conventional technique, and good viewing angle characteristics are obtained.

[0099]

Second Embodiment FIG. 4 shows a liquid crystal display panel 100 according to a second embodiment of the present invention.
Polarizing plates (not shown) are arranged on both sides of 0.

The liquid crystal display panel 100 is one in which a liquid crystal 20 is sealed between a pair of transparent substrates 11 and 12. A pixel electrode 71 and an alignment film 31 are provided on the inner surface of the substrate 11 on the lower side of FIG. The pixel electrode 71 is connected to an active matrix circuit (not shown). A common electrode 72 of ITO is provided inside the upper substrate 12. The alignment film 32 is provided on the common electrode 72.

The alignment treatment method for the first substrate 11 in the present embodiment is exactly the same as the alignment treatment method for the liquid crystal display panel of the first embodiment shown in FIG.

On the other hand, the alignment treatment method for the second substrate (upper substrate) 12 is simpler than this.

That is, SE-7210 (0321) manufactured by Nissan Chemical Industries, Ltd. was applied onto the substrate 12, baked in an oven at 200 ° C. for 1 hour, and then rubbed in a fixed direction. SE-7210 (0321) is a liquid crystal alignment film material containing polyamic acid as a main component, and in a normal usage, that is, the same usage as that performed on the second substrate 12 according to the present embodiment. The pretilt angle of the liquid crystal molecules when the liquid crystal molecules are brought into contact with the surface of the alignment film is about 6 degrees.

The substrates thus aligned were stacked in the same manner as in the first embodiment, and the counterclockwise chiral agent-added nematic liquid crystal 20 was inserted between the substrates. The liquid crystal 20 is in a splay type twisted nematic type alignment state as a whole.

In this liquid crystal display panel, the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle was 10 degrees in the exposed area and 1 degree in the unexposed area on the surface of the alignment film during the exposure process shown in FIG. 2B. On the other hand, with respect to the second substrate, it was uniformly 6 degrees.

As described above, in this embodiment, the alignment state of the liquid crystal 20 is different for each of the minute regions A and B shown in FIG.

That is, in the minute area A, the lower substrate 1
The pre-tilt angle α near the surface of No. 1 is the upper substrate 12
Is larger than the pretilt angle γ near the surface of the substrate, and in the minute region B, the pretilt angle γ near the surface of the upper substrate 12 is
Is larger than the pretilt angle β near the surface of the lower substrate 11.

When a voltage is applied, the minute area A,
For each B, it was confirmed that the liquid crystal rises in accordance with the pretilt direction having the larger pretilt angle on the surfaces of both substrates 11 and 12. That is, in the minute region A, the rising occurs in accordance with the pretilt direction near the surface of the lower substrate 11, and in the minute region B, the rising occurs in accordance with the pretilt direction near the surface of the upper substrate 12.

As described above, the rising directions of the liquid crystal molecules at the time of voltage application are different between the minute areas A and B, and the asymmetrical viewing angle characteristics of the respective minute areas are averaged and recognized by the observer. In contrast, the viewing angle characteristic that the display can be recognized from a wider viewing angle range than the conventional one was obtained.

[0110]

[Third Embodiment] A third embodiment of the present invention is similar to the first embodiment, except that SE-1180 (0322) is used.
The liquid crystal alignment film material was adjusted by changing the mixing ratio of the photo-crosslinking agent and the low molecular weight compound having a long-chain alkyl group. That is, 100 g of SE-1180 (0322)
, 2,6-bis (4'-azidobenzal) 4-
A liquid crystal alignment film material was prepared by adding 3 g to 1 g of methylcyclohexanone and 0.3 g to 0.1 g of stearyl acrylate.

A liquid crystal display panel was prepared by using the liquid crystal alignment film materials having the respective mixing ratios and the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured. Table 1 shows the measurement results of the pretilt angle.

[0112]

[Table 1]

[0113]

[Embodiment 4] 3 g of a polyamic acid (Chemical Formula 21) synthesized by using pyromellitic dianhydride and 4,4′-diaminodiphenyl ether as raw materials was dissolved in 100 g of N-methyl-2-pyrrolidinone to prepare a first embodiment. Like 2, 6
3 g (3% by weight) of -bis (4'-azidobenzal) 4-methylcyclohexanone and 0.3 g (0.3% by weight) of stearyl acrylate were added to adjust the liquid crystal alignment film material.

[0114]

Embedded image

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates 11 and 12 were measured. It was found that the pretilt angle measurement result was 12 degrees in the exposed portion on the surface of the alignment film and 2 degrees in the unexposed portion, and the magnitude of the pretilt angle was different.

[0116]

[Embodiment 5] 3 g of a polyamic acid (Chemical Formula 21) synthesized from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether as a raw material is dissolved in 100 g of N-methyl-2-pyrrolidinone, and represented by Chemical Formula 1 , 3-bis (4'-azidocinnamylidene) -2-propanone 3
g (3% by weight), stearyl acrylate 0.3 g
(0.3% by weight) to adjust the liquid crystal alignment film material.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured. It was found that the pretilt angle measurement result was 12 degrees in the exposed portion on the surface of the alignment film and 2 degrees in the unexposed portion, and the magnitude of the pretilt angle was different.

[0118]

Embodiment 6 3 g of polyamic acid (Chemical Formula 21) synthesized from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether as a raw material are dissolved in 100 g of N-methyl-2-pyrrolidinone to give 1 shown in Chemical Formula 3. , 3-bis (4'-azidobenzal) -2-propanone (3 g (3
% By weight) and 0.3 g (0.3% by weight) of lauryl acrylate represented by Chemical Formula 11 were added to adjust the liquid crystal alignment film material.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured.
The measurement result of the pretilt angle is 5 at the photosensitive part on the surface of the alignment film
It was found that the pre-tilt angle was different, since the unexposed area was 2 degrees.

[0120]

[Embodiment 7] 3 g of a polyamic acid (Chemical Formula 21) synthesized from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether as a raw material is dissolved in 100 g of N-methyl-2-pyrrolidinone, and represented by Chemical Formula 1 , 6-bis (4'-azidobenzal) 4-methylcyclohexanone (3 g (3% by weight)) and stearyl methacrylate represented by the chemical formula 18 (0.3 g, 0.3% by weight) were added to adjust the liquid crystal alignment film material. did.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured.

The pretilt angle was measured at the exposed portion of the alignment film surface of 10 ° and at the unexposed portion of 1 °, showing that the pretilt angle was different.

[0123]

[Embodiment 8] 20 g of a polyimide varnish LQ-2200 manufactured by Hitachi Chemical Co., Ltd. is diluted with N-methyl-2-pyrrolidinone to a total amount of 100 g.
3 g (3% by weight) of 6-bis (4′-azidobenzal) 4-methylcyclohexanone and 0.3 g (0.3% by weight) of stearyl acrylate represented by Chemical Formula 10 were added to adjust the liquid crystal alignment film material. . In addition, LQ-2
200 is a main component (1
The liquid crystal alignment film material has a pretilt angle of about 2 degrees.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle was 10 degrees at the exposed portion on the surface of the alignment film and 2 degrees at the unexposed portion, and it was found that the magnitude of the pretilt angle was different.

[0125]

Comparative Example 1 3 g of a polyamic acid (Chemical Formula 21) synthesized by using pyromellitic anhydride and 4,4′-diaminodiphenyl ether as raw materials was dissolved in 100 g of N-methyl-2-pyrrolidinone, and represented by Chemical Formula 1 , 6-bis (4 '
-Azidobenzal) 3 g of 4-methylcyclohexanone
(3% by weight) and 0.3 g (0.3% by weight) of undecyl acrylate represented by the chemical formula 22 were added to adjust the liquid crystal alignment film material.

[0126]

Embedded image

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those shown in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle is 3 degrees at the photosensitive part on the alignment film surface,
Although the pre-tilt angle is 2 degrees in the unexposed portion and the magnitude of the pre-tilt angle is different, the liquid crystal orientation divided into minute regions is similar to that in the first embodiment because the difference in the magnitude of the pre-tilt angle is small. Therefore, the effect of widening the viewing angle could not be obtained.

[0128]

Comparative Example 2 3 g of polyamic acid (Chemical Formula 21) synthesized from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether as raw materials was dissolved in 100 g of N-methyl-2-pyrrolidinone, and represented by Chemical Formula 1 , 6-bis (4 '
-Azidobenzal) 3 g of 4-methylcyclohexanone
(3% by weight) and 0.3 g (0.3% by weight) of eicosyl acrylate represented by Chemical Formula 23 were added to adjust the liquid crystal alignment film material.

[0129]

Embedded image

When this liquid crystal alignment film material was applied to the substrate 11 to form the liquid crystal alignment film 31, a uniform film could not be obtained due to poor compatibility between polyamic acid and eicosyl acrylate.

[0131]

As described above, according to the present invention,
With the aim of widening the viewing angle, a liquid crystal display panel that has been subjected to an alignment treatment in which the alignment state of the liquid crystal is different for each minute region, the alignment film can be made into a minute region only by adding an ultraviolet irradiation process to the normal process. Correspondingly, it is possible to realize with one rubbing process for one substrate without partially forming a two-layer structure, which simplifies the manufacturing process and achieves cost reduction. ing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

2A to 2C are cross-sectional views schematically showing an alignment treatment of the liquid crystal display panel of FIG.

3 is a diagram showing a rubbing direction of the substrate of FIG.

FIG. 4 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a structure of a conventional liquid crystal display panel in which an alignment state is different for each minute region.

FIG. 6 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state is different for each minute region.

7A to 7E are cross-sectional views schematically showing the alignment treatment process of the liquid crystal display panel of FIG. 6 in order.

FIG. 8 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state is different for each minute region.

[Explanation of symbols]

 11, 12 substrate 20 liquid crystal 31, 32 alignment film 40 resist material 51 alignment film layer of first layer 52 alignment film layer of second layer 60 photomask 71 pixel electrode 72 common electrode 80 rubbing roller 100 liquid crystal display panel

Claims (14)

[Claims] 1. A liquid crystal alignment film material comprising a mixture of a polyimide or a polyimide precursor, a photo-crosslinking agent, and a low-molecular compound having a long-chain alkyl group. 2. The liquid crystal alignment film material according to claim 1, wherein the polyimide precursor is a polyamic acid. 3. The photocrosslinking agent has at least 2 azido groups.
It consists of a compound which has one or more pieces.
Alternatively, the liquid crystal alignment film material according to claim 2. 4. The liquid crystal alignment film material according to claim 1, wherein the low molecular weight compound having a long chain alkyl group is a compound having an unsaturated bond. 5. The liquid crystal alignment film material according to claim 1, wherein the low molecular weight compound having a long chain alkyl group is a long chain alkyl acrylate. 6. The liquid crystal alignment film material according to claim 5, wherein the carbon number of the long-chain alkyl group is 12 or more and 19 or less. 7. A first and second substrate provided with an alignment film and facing each other, and a nematic liquid crystal in a splay type twisted nematic type alignment state inserted between the first and second substrates. An alignment treatment is performed such that the alignment film of at least one of the first and second substrates has a different pretilt angle of liquid crystal near the surface of the alignment film for each minute region. A method of manufacturing a liquid crystal display panel comprising: (a) at least one of the first and second substrates having a polyimide or a polyimide precursor, a photocrosslinking agent, and a long-chain alkyl group. A step of applying a liquid crystal alignment film material containing a mixture of a low molecular weight compound and a liquid crystal alignment film to form a liquid crystal alignment film; and (b) irradiating the liquid crystal alignment film with ultraviolet rays through a photomask having a predetermined pattern. Process and a step of forming a fine alignment region, comprising: (c) baking the liquid crystal alignment film; and (d) rubbing the surface of the alignment film in a predetermined direction. Liquid crystal display panel manufacturing method. 8. The method for producing a liquid crystal display panel according to claim 7, wherein the polyimide precursor of the liquid crystal alignment film material is polyamic acid. 9. The photocrosslinking agent of the liquid crystal alignment film material,
9. The method for producing a liquid crystal display panel according to claim 7, which comprises a compound having at least two azido groups. 10. The liquid crystal alignment film material according to claim 7, wherein the low-molecular-weight compound having a long-chain alkyl group is a compound having an unsaturated bond. Of manufacturing liquid crystal display panel of. 11. The low-molecular compound having a long-chain alkyl group of the liquid crystal alignment film material is a long-chain alkyl acrylate, according to any one of claims 7 to 10. Liquid crystal display panel manufacturing method. 12. The method of manufacturing a liquid crystal display panel according to claim 11, wherein the long-chain alkyl group in the liquid crystal alignment film material has a carbon number of 12 or more and 19 or less. 13. The alignment films of the first and second substrates are subjected to alignment treatment such that the magnitude of the pretilt angle of liquid crystal near the alignment film surface is different for each minute region, and then the first alignment film is formed. A region of the substrate having a large pretilt angle in the vicinity of the surface of the alignment film faces a region of the second substrate having a small pretilt angle in the vicinity of the surface of the alignment film, and a surface of the alignment film of the first substrate. A step of superposing the first substrate and the second substrate such that a region having a small pretilt angle in the vicinity faces a region having a large pretilt angle in the vicinity of the surface of the alignment film of the second substrate. The method for manufacturing a liquid crystal display panel according to claim 7, further comprising: 14. A first and second substrate provided with an alignment film and facing each other, and a nematic liquid crystal in a splay type twisted nematic type alignment state, which is inserted between the first and second substrates. And the alignment film on at least one of the first and second substrates is made of the liquid crystal alignment film material according to any one of claims 1 to 6, and A liquid crystal display panel, characterized in that it is subjected to an alignment treatment such that the magnitude of the pretilt angle of the liquid crystal near the surface of the alignment film is different.