JPH08254701A - Oriented film for liquid crystal display element, liquid crystal display element and production of oriented film - Google Patents

Abstract

PURPOSE: To prevent the occurrence of dust or electrostatic charges in the production process, to decrease the production cost and to obtain an oriented film showing an enough pretilt angle in a short time by constituting the film of a polymer compd. comprising polyvinyl cinnamate with addition of a specified compd. CONSTITUTION: This film consists of a polymer compd. material comprising polyvinyl cinnamate with addition of 6-biphenyloxy alkylacrylate compd. expressed by formula. In formula, n is an integer 1 to 20, X is H or alkyl group, Y is one of H, CN, F, Cl, Br, I and alkyl groups. In this method, the amt. of this compd. in the polymer compd. material is preferably between >=10wt.% and <=85wt%. Further, the amt. of 6-biphenyloxy alkylacrylate compd. in the polymer compd. material is preferably between, >=20wt.% and <=75wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device for aligning liquid crystal molecules in a predetermined direction for various displays, an alignment film provided in the liquid crystal display device, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, various displays such as televisions and image devices connected to a computer are required to be lighter, thinner, and have lower power consumption. Under such circumstances, the emergence of an excellent liquid crystal display device has been desired as a device for realizing a flat display that satisfies the above requirements.

The liquid crystal display element is provided with an alignment film having a pretilt angle set on the surface in order to align the liquid crystal in a certain direction. As a method for producing an alignment film, a rubbing treatment is performed in which a polymer resin film such as a polyimide resin film formed on a substrate is rubbed in one direction with a cloth, or silicon dioxide (SiO ₂ ) is obliquely vapor-deposited. The method is known.

[0004]

However, in the case of an alignment film formed by using a rubbing process, when rubbing with a cloth or the like to produce this alignment film, dust is generated or static electricity is generated. There is a problem that occurs. In addition, in the method using the oblique deposition, the manufacturing cost increases and
It is difficult to form a large area and there is a problem that it is not suitable for a relatively large liquid crystal display element.

Therefore, in recent years, in order to solve such a problem, a method of manufacturing an alignment film by using a transfer method has come into the limelight. The method for producing an alignment film by this transfer method is a method of transferring an uneven shape to the surface of a film by pressing a transfer mold having an uneven pattern to be transferred formed on the surface of a resin film formed on a substrate while heating. To form. In general, the surface shape of the alignment film manufactured by this transfer mold is a shape in which a large number of convex shapes are repeatedly formed in parallel on a substrate.

However, in the liquid crystal display element using the alignment film only having the concavo-convex shape formed by the transfer method, the interface regulating force of the liquid crystal is weak, and a sufficient pretilt angle can be obtained by applying external force or heat. (Generally, 1 ° or more) is not maintained, and so-called domain may occur.

Further, in recent years, a polymer compound (polyvinylcinnamate: hereinafter abbreviated as PVCn) obtained by polymerizing a monomer represented by the following chemical formula is not on the rubbing treatment or the transfer method by the transfer type as described above on a substrate. After being uniformly coated and formed into a film, the film is irradiated with ultraviolet rays polarized in a specific direction, and is oriented in the polarization direction of the ultraviolet rays to be irradiated.
A method of manufacturing an alignment film as an anisotropic network polymer by crosslinking only the photosensitive groups of VCn has been studied.

[0008]

[Chemical 6] This method is a non-contact method in which the resin film applied on the substrate is in contact with other members, which is indispensable for rubbing treatment, etc., and therefore has advantages such as no generation of static electricity and mixing of impurities. is there.

However, the resin applied to this method has low photosensitivity, and in order to perform a sufficient alignment treatment as an alignment film of a liquid crystal display element, the irradiation time of polarized ultraviolet rays must be lengthened, and The process took a long time. In other words, if the alignment treatment is completed in an industrially suitable time, the liquid crystal of the manufactured liquid crystal display element will be insufficiently aligned, the dichroic ratio will be small, and the contrast will be poor. This is because the photosensitive group needs to be able to move freely in order for the photosensitive group of the polymer to face the polarization direction.
In Cn, since the photosensitive group is only present in the polymer, the photosensitive group is bound to the main chain of the polymer, and the rapid movement of the photosensitive group is hindered. Therefore, it is considered that it takes a long time to become a network polymer.

Further, the interaction with the liquid crystal is weak, it is difficult to align the liquid crystal uniformly, and many fine domains are generated. Further, since the dielectric constant is low, in order to apply a sufficient voltage to the liquid crystal, it is necessary to make the alignment film as thin as possible, which requires high precision in the manufacturing process and hinders the improvement of the yield.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to prevent the generation of dust and static electricity in the manufacturing process, and to reduce the manufacturing cost in a short time, and to have an orientation having a sufficient pretilt angle. The present invention provides a film, a liquid crystal display device including the alignment film, or a method for manufacturing the alignment film.

[0012]

The alignment film for a liquid crystal display device of the present invention comprises a polymer compound material obtained by adding a 6-biphenyloxyalkyl acrylate compound having the following chemical formula to polyvinyl cinnamate. It is a feature.

[Chemical 7] In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.

At this time, the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material is 10
It is preferably not less than wt% and not more than 85 wt%.

Further, the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material is 2
It is preferably 0 wt% or more and 75 wt% or less.

The liquid crystal display device of the present invention is characterized by comprising an alignment film made of a polymer compound material obtained by adding a 6-biphenyloxyalkyl acrylate compound having the following chemical formula to polyvinyl cinnamate. Is.

Embedded image In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.

At this time, the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material constituting the alignment film is preferably 10 wt% or more and 85 wt% or less.

Further, it is more preferable that the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material constituting the alignment film is 20 wt% or more and 75 wt% or less.

In the method for producing an alignment film of the present invention, a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula is applied on a substrate to form a film, and then polarized ultraviolet rays are irradiated. Then, anisotropy is given to the surface of the film.

[Chemical 9] In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.

In the method for producing an alignment film according to claim 8, a polymer compound film is formed by coating a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula on a substrate. And the process of
A transfer mold having a pressure contact surface formed by repeatedly forming a long side portion and a short side portion along an arbitrary direction is pressed against the polymer compound film to form a long side on the surface of the polymer compound film. And a step of irradiating the polymer compound film with ultraviolet rays polarized in a direction substantially orthogonal to the first direction. It is characterized by having.

[Chemical 10] In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.

In the method for producing an alignment film according to claim 9, a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula is applied on a substrate to form a polymer compound film. And the process of
A ridge-shaped irregularity row formed by repeatedly forming a convex portion composed of a long side portion and a short side portion along an arbitrary direction, and a height lower than the ridge-shaped irregularity row, and in the same direction as the ridge-shaped irregularity row The valley-shaped concave-convex row formed along with the concave-convex pattern has a repeating unit length shorter than the repeating unit length of the concave-convex pattern formed along the arbitrary direction and alternately formed adjacent to each other. A transfer mold having a pressure contact surface formed along a direction substantially orthogonal to is pressed against the surface of the polymer compound film, and is repeatedly formed on the surface of the polymer compound film along the first direction. A concave-convex row having a long unit length and a concave-convex row having a repeating unit length shorter than the repeating unit length of the concave-convex row along the first direction along a second direction substantially orthogonal to the first direction. A step of forming and a polymer compound film for ultraviolet rays polarized along the second direction Method for producing oriented film, characterized by a step of irradiating.

[Chemical 11] In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.

[0021]

In the present invention, a polymer compound material obtained by adding a 6-biphenyloxyalkyl acrylate compound to polyvinyl cinnamate is used as the alignment film. Polyvinyl cinnamate is represented by the following chemical formula, 6-
The biphenyloxyalkyl acrylate compound is represented by a chemical formula.

[0022]

[Chemical 12] Here, m is an arbitrary integer, and Z is -N (CH ₃ ) ₂ ,-.
It is halogen such as OCH ₃ , —NO ₂ , —CN, F and Cl.

[Chemical 13] Here, n is an arbitrary integer, but is preferably 1 or more and 20 or less. Furthermore, 3 or more and 12 or less are more preferable. When n is larger than 20, it becomes difficult to cure and it becomes difficult to obtain the orientation of the liquid crystal, which is not preferable. Further, X is —H or an alkyl group such as a methyl group, and Y is —H, —CN, halogen, an alkyl group or the like. Of these, a cyano group is preferable.

The content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound is 10
It is preferably not less than wt% and not more than 85 wt%. Furthermore, 2
More preferably, it is 0 wt% or more and 75 wt% or less. The content of the 6-biphenyloxyalkyl acrylate compound is
If it is less than 10 wt%, the sensitizing action becomes insufficient and it takes a long time to perform a sufficient alignment treatment. If the content is more than 85 wt%, the polymerization of the monomers progresses, resulting in an alignment film. This is because the alignment regulating force of the liquid crystal is reduced.

In the polymer compound material of the present invention, the monomer of the 6-biphenyloxyalkyl acrylate compound, which is a polarized UV crosslinking compound not bound to the main chain, is present in the polymer of polyvinylcinnamate. It is structured so that the photosensitive group can move around relatively freely. The polymer compound material of the present invention,
Photosensitivity is about 1. compared to polyvinyl cinnamate alone.
It will be 5 times. Therefore, it becomes possible to perform a sufficient alignment treatment by irradiating polarized ultraviolet light for a short time. Therefore, the manufacturing time can be shortened and the production cost can be reduced. That is, the irradiation time of the ultraviolet rays can be about 2/3 as compared with the polymer resin composed only of polyvinyl cinnamate. In other words, if a certain irradiation time is required, the alignment regulating force of the liquid crystal can be increased and the dichroic ratio can be increased as compared with the conventional one. Further, the alignment film of the present invention has a strong interaction with the liquid crystal, can align the liquid crystal uniformly, and can suppress the generation of domains. Further, the dielectric constant is not low, and even if a sufficient voltage is applied to the liquid crystal, the requirement for thinning the alignment film is relaxed, high accuracy is not required in the manufacturing process, and the yield can be improved.

Further, since the alignment treatment can be performed only by irradiating the polarized ultraviolet rays, unlike the rubbing treatment or the like, the non-contact type can be realized and the generation of static electricity and the mixing of impurities can be prevented. .

Incidentally, not only irradiation of polarized ultraviolet rays but also transfer method of pressing the transfer mold can be used together. When this transfer method is used in combination, the contact method can be performed, but the alignment treatment can be performed more reliably, and the dichroic ratio can be improved. Further, by using the specific polymer material of the present invention for the alignment film, it is possible to maintain a sufficient pretilt angle even when an external force or heat is applied, and it is possible to suppress the generation of domains.

When used in combination with this transfer method, the polarization direction of the polarized ultraviolet rays to be irradiated needs to be substantially orthogonal to the first direction, which is the direction in which the convex portions previously formed by the transfer mold are repeated. Is.

[0028]

EXAMPLES The alignment film and the method for producing the same according to the present invention can be applied to various liquid crystal display devices having an alignment film. An example of the liquid crystal display element is shown in FIG. The illustrated color liquid crystal display device 10 includes a pair of substrates 12 and 14 arranged to face each other.
And the liquid crystal 16 enclosed between them and the one substrate 1
2 and the transparent electrode (pixel electrode) 20 (20a, 20a, which is connected to the liquid crystal driving element 18)
20b, 20c), a counter electrode 22 formed on the other substrate 14 so as to face the transparent electrode 20, alignment films 24, 24 for sandwiching the liquid crystal 16, and a pair of substrates 12, 14. The polarizing filter (lower polarizing filter 26, upper polarizing filter 28) and the color filters 30 (30r, 30g, 30b) formed on the substrate 14 are included in the schematic configuration.

As the substrates 12 and 14, those used in general liquid crystal display elements can be applied, and various ones such as glass substrates and ceramics can be applied. A shape corresponding to the liquid crystal display element as a product is also used, and an arbitrary shape such as a plane rectangular shape is used. The liquid crystal 16 changes the orientation state of molecules by applying a voltage. For example, in the TN type liquid crystal shown as an example in FIG. 1, the molecules which are twisted by 90 ° when no voltage is applied are used. By applying a voltage, the column stands upright and the twist is eliminated. Although not shown in FIG. 1, both alignment films 2
A spacer made of fine particles or the like is interposed between the Nos. 4 and 24, and the spacer keeps the gap in which the liquid crystal is sealed at a predetermined gap.

A thin film transistor (TFT) or the like is applied to the liquid crystal drive element 18, and the voltage applied to the liquid crystal is controlled by a drive signal. Transparent electrode 20
Forms a pair with the counter electrode 22 formed on the other substrate 14 and applies a voltage from the liquid crystal drive element 18 to the liquid crystal 16. Generally, an ITO film (indium oxide film) or the like is applied. The liquid crystal driving element 18 and the transparent electrode 20
Although (20a, 20b, 20c) is provided for each pixel, the counter electrode 22 is generally configured as a common electrode common to each pixel.

The alignment film 24 is for aligning the liquid crystal 16 in a predetermined direction, and in this embodiment, a polymer compound obtained by adding a 6-biphenyloxyalkyl acrylate compound satisfying the above chemical formula to polyvinyl cinnamate. Made of material.

The polarizing filters 26 and 28 are films having a function of emitting linearly polarized light. In the illustrated liquid crystal display element 10, the lower filter 26 and the upper filter 28 formed on the substrates 12 and 14 are It is provided so that the polarization directions thereof are relatively different by 90 °. The color filter 30 is used in a color liquid crystal display element, and normally, three color filters of red, green, and blue are used for each pixel to form a set. In a color liquid crystal display element, various colors are expressed by combining these three colors.

In the color liquid crystal display element shown in FIG.
First, light rays from the lower side of the polarizing filter 26 pass through the lower polarizing filter 26 as a backlight. At this time, only the light beam polarized in the lateral direction of FIG.
Through 6. In the example shown in FIG. 1, under the control of the liquid crystal drive elements 18, 18, ..., No current is passed through the transparent electrodes 20a and 20b, and a voltage is applied only to the liquid crystal on the transparent electrode 20c. It has become so.

In this state, the lower polarization filter 26
As for the polarized light transmitted through the glass substrate 12 and the alignment film 24, only the polarized light along the twisted liquid crystal molecules on the transparent electrodes 20a and 20b is converted in the polarization direction and transmitted through the upper polarization filter 28. Come to do. At this time, by providing a color filter 30r that transmits only red color, a color filter 30g that transmits only green color, and a color filter 30b that transmits only blue color so as to face each transparent electrode 20a, 20b, 20c, Above the upper polarizing filter 28, blue light rays are not transmitted, only red light rays and green light rays are transmitted, resulting in yellow display.

The alignment film in this embodiment is a substrate 12 having a transparent electrode 20 which is a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound.
It is manufactured by coating the above with a film and then irradiating polarized ultraviolet rays polarized in a predetermined direction to give anisotropy to the surface of the film. If unpolarized isotropic ultraviolet rays are irradiated before the polarized ultraviolet rays are irradiated, the distance between the photosensitive groups that are reaction sites is shortened, and the reaction can be further promoted.

The coating of the polymer compound material used for the alignment film in the present invention on the substrate is not particularly limited, but spin coating, screen printing method, offset printing method or the like is applied. In addition, a polymer compound film is formed by drying by baking treatment, if necessary, such as by removing the solvent. At this time, the polymer compound film may be further pre-baked and baked if necessary. The pre-baking and the baking can be performed, for example, by heating the substrate at 80 ° C. for about 30 seconds and then at 180 ° C. for 1 hour. Further, the substrate may be preheated to about 80 ° C., screen printed, coated with the solution, and then baked.

When the solution is applied by the screen printing method, the printing stage is directed through the screen installed on the substrate in the longitudinal direction, the lateral direction or the oblique direction of the substrate at a predetermined speed, for example, 10 cm / It can be done by moving at a speed of 2 seconds. The thickness of the polymer compound film formed by coating the polymer compound unique to the present invention is 0.
About 1 μm is preferable.

In addition to the irradiation of polarized ultraviolet light, a transfer method of pressing the transfer mold against the surface of the film can be used together. When used in combination with the transfer method, the polarization direction of the polarized ultraviolet light to be irradiated needs to be substantially orthogonal to the first direction in which the convex portions previously formed by the transfer mold are repeated. That is, referring to FIG. 2 showing an example of the shape of the alignment film, the first protrusions 36, 36, ... Ultraviolet rays having a polarization direction along a second direction substantially orthogonal to the first direction are irradiated.

As shown in FIG. 3, the surface of the alignment film formed by the transfer mold has a long side portion 32 'and a short side portion 34'.
And a ridge-like concavo-convex row 38 formed by repeatedly forming a convex portion 36 ′ consisting of the ridge-like concavo-convex row 38, which is lower than the ridge-like concavo-convex row 38 The valley-shaped concave-convex rows 40 to be formed are alternately formed adjacent to each other, and the concave-convex rows having a long repeating unit length U formed along the first direction and the second concave-convex rows that are substantially orthogonal to the first direction. And a concave-convex row having a repeating unit length U ′ shorter than the repeating unit length U of the concave-convex row along the first direction, the polarized light is polarized along the second direction. Irradiate with ultraviolet rays.

The repeating unit length U of the unevenness along the first direction is 50 μm or less, and the repeating unit length U ′ along the second direction.
Is preferably 3 μm or less. More preferably, the repeating unit length U is 20 μm or less and the repeating unit length U ′ is 1.2 μm or less. Furthermore, as shown in FIG. 4, the inclination angle θ of the ridgeline of the long side portion 32 is desired to be 1 ° or more.

Further, as shown in FIG. 4, it is desirable that each of the convex and concave portions 36 along the first direction has a substantially triangular shape whose left and right are asymmetric. That is, the ratio r ₂ / r ₁ of the right and left angles of the apex angle divided by the perpendicular drawn from the apex of the convex portion 36.
Has a shape that does not become 1. As the shape of the convex portion 36, various shapes such as a shape similar to a sin wave, a comb shape, and a triangular shape can be considered. In the case of a triangular shape, the top may be rounded or flatly cut. Convex portion 36
In the case of a triangular shape, it is desired that the ratio r ₂ / r ₁ of the left and right angles of the apex angle divided by the perpendicular drawn from the apex of the triangle is 1.2 or more.

In the transfer method, for example, a manufacturing apparatus as shown in FIG. 5 can be applied. The manufacturing apparatus 42 shown in FIG.
Is roughly configured by including a pedestal 46 as a holding mechanism for the substrate 12, an upper plate 44 as a transfer mechanism vertically provided above the pedestal 46, and an ultraviolet irradiation mechanism 48. The pedestal 46 is for mounting the substrate 12, and the smooth polymer compound film 2 before the unevenness is formed on the upper surface of the substrate 12 mounted on the pedestal 44.
4'is formed.

The upper plate 44, which is a transfer mechanism, moves up and down by a moving mechanism (not shown) to move the polymer compound film 24 '.
The concave portion 50 is formed on the lower surface of the concave portion 50, and the transfer mold 52 is mounted in the concave portion 50. In addition, a concavo-convex pattern in which a concavo-convex pattern to be formed on the upper surface of the alignment film 24 is formed on the lower surface of the transfer mold 52. Further, a protruding stopper 54 is formed in the peripheral portion of the recess 50, and the stopper 54 abuts the upper surface of the pedestal 46 to stop the lowering of the upper plate 44. Therefore, when the stopper 54 of the upper plate 44 contacts the upper surface of the pedestal 46, the upper plate 4
4 has stopped descending, and the transfer compound 52 polymer compound film 24 '
Is stopped, and an uneven pattern having a specified depth is formed on the upper surface of the polymer compound film 24 '. The polarized ultraviolet irradiation mechanism 48 also includes an ultraviolet light source 56 that emits ultraviolet light.
And a polarizer 58 that polarizes the ultraviolet light emitted from the ultraviolet light source 56, and irradiates the polymer compound film 24 'with the polarized ultraviolet light.

In order to manufacture an alignment film using this manufacturing apparatus 42, first, the substrate 12 on which the polymer compound film 24 'made of the compound unique to the present invention is formed is placed on the pedestal 46. Then, the upper plate 44 is lowered. Then
Since the transfer mold 52 is pressed onto the upper surface of the polymer compound film 24 ', the uneven pattern on the lower surface of the transfer mold 52 is transferred onto the upper surface of the polymer compound film 24' to form the uneven pattern as shown in FIGS. The aligned film 24 thus obtained is obtained. After that, polarized ultraviolet rays polarized in the second direction of the concavo-convex pattern formed on the polymer compound film are irradiated by the polarized ultraviolet irradiation mechanism 48 to be cured.

[Preparation of 6- (4′-cyanobiphenyl) oxyhexyl acrylate] 6- (4′-cyanobiphenyl) added to the polymer compound material constituting the alignment film
An example of preparation of oxyhexyl acrylate (n = 6, X = -H, Y = -CN in the above chemical formula) is shown. First, a three-necked flask (1 L) equipped with a cooling tube and a stirrer
Then, 500 ml of dimethylformamide, 4-hydroxy-
19.6 g of 4'-cyanobiphenyl, (0.10 mol),
41.4 g (0.30 mol) of potassium carbonate was added, and the mixture was stirred at room temperature. Then add 6-chromium-1-hexanol to 1
6.4 g (0.12 mol) was added, and the mixture was vigorously stirred at 100 ° C. After reacting for 10 hours, this solution was added to 2 liters of water and extracted with 1.5 L of ethyl acetate. Subsequently, the organic layer was washed 3 times with 3N hydrochloric acid, 3 times with 2N aqueous sodium hydroxide solution, and further washed with water. The obtained ethyl acetate layer was dried over anhydrous sodium sulfate solution, the solvent was distilled off under reduced pressure, and the obtained crystals were recrystallized twice with ethyl acetate to give 6-
18. Add (4'-cyanobiphenyl) oxyhexanol.
3 g (0.062 mol) was obtained. Its melting point (C-S point) is
It was 91.3-92.5 degreeC. The reaction up to this point is represented by the following chemical reaction formula. However, Y is a cyano group.

Embedded image

Subsequently, 300 ml of tetrahydrofuran (THF) was placed in a 500 ml three-necked flask equipped with a stirrer, and 14.8 g (0.050 mol) of 6- (4'-cyanobiphenyl) oxyhexanol prepared above was added.
Then, 8.4 ml of triethylamine was added, and the mixture was stirred at 0 ° C. To this, 5.43 g (0.0) of acrylic acid chloride
A solution prepared by dissolving 60 mol) in 30 ml of THF was added dropwise over 30 minutes, and the reaction was carried out for 6 hours as it was. This reaction is represented by a chemical formula. However, X is hydrogen.

[Chemical 15]

After the reaction was completed, this solution was added to 1 L of water,
It was extracted with 1.5 L of ethyl acetate. Then, the organic layer is 3N
The extract was washed 3 times with hydrochloric acid, 3 times with saturated aqueous sodium hydrogen carbonate, and further washed with water.
The resulting ethyl acetate layer was dried over anhydrous sodium sulfate,
The solvent was distilled off under reduced pressure, and the obtained crystal was dissolved in a small amount of ethyl acetate and purified with a silica gel column (n-heptane / ethyl acetate). The obtained crystals were recrystallized from n-heptane / ethyl acetate to obtain 10.5 g (0.030 mol) of 6- (4'-cyanobiphenyl) oxyhexyl acrylate. The melting point of this compound was 70.4 to 72.2 ° C.

[Preparation of 6- (4′-cyanobiphenyl) oxyhexyl methacrylate] 6- (4′-cyanobiphenyl) oxyhexyl methacrylate added to the polymer compound material constituting the alignment film (In the above chemical formula, n = 6, X = -CH ₃ , Y = -CN) is prepared. In the preparation of 6- (4′-cyanobiphenyl) oxyhexyl acrylate, 6.27 g of methacrylic acid chloride was used instead of acrylic acid chloride.
12.3 g (0.034 mol) of 6- (4'-cyanobiphenyl) oxyhexyl methacrylate was obtained in the same manner as in the above preparation except that (0.060 mol) was used. The melting point of this compound was 74.1 to 75.9 ° C.

[Test Example 1] 3 wt% of polyvinyl cinnamate and 20 wt% of 6- (4′-cyanobiphenyl) oxyhexyl acrylate prepared above were added to γ-butyrolactone as a solvent. Then, this solution was uniformly applied by offset printing on a glass substrate on the surface of which an ITO electrode was formed, and heated at 80 ° C. for 1 minute and then at 180 ° C. for 1 hour to vaporize the solvent. It was dried to form a film made of a polymer compound. Next, 1 nm of polarized ultraviolet light (5 mW) with a wavelength of 310 nm is applied to the film of this substrate.
Irradiation was carried out for 0 minutes to prepare a substrate on which an alignment film was formed.
Upon irradiation with ultraviolet rays, the extinction ratio of the polarizing prism was 10 ⁻⁵ , the energy density of irradiation was 1.5 J / cm ² , and the substrate was heated to 80 ° C. The two substrates produced by this process were opposed to each other with a spacer interposed therebetween, and a liquid crystal (“K-15” manufactured by Merck Ltd.) was injected therebetween. The distance between the substrates was 10 μm. A heat treatment was performed again to manufacture a liquid crystal display element. In this liquid crystal display element, a voltage was applied to ITO and the alignment state of the liquid crystal was observed. As a result, a uniform orientation with almost no domains was obtained.

[Test Example 2] In the above Test Example 1, 6-
Using 6- (4'-cyanobiphenyl) oxyhexyl methacrylate instead of (4'-cyanobiphenyl) oxyhexyl acrylate, a test sample of a liquid crystal display device was similarly prepared, and the alignment state was measured. Was observed. As a result, a uniform orientation with almost no domains was obtained.

[Test Example 3] 3 wt% of polyvinyl cinnamate and 6- (4'-cyanobiphenyl) oxyhexyl acrylate, which is a prepared monomer, were added to γ-butyrolactone as a solvent. Then, in the same manner as in Test Example 1, this solution was uniformly applied by offset printing on a glass substrate having a surface-cleaned ITO electrode and was applied at 80 ° C. for 1 minute, and then at 180 ° C. for 1 hour. It was heated to evaporate the solvent and dried to form a film made of a polymer compound. Next, the film of this substrate has a wavelength of 310 nm.
Was irradiated with polarized ultraviolet light (5 mW) for 10 minutes to prepare a substrate having an alignment film formed thereon. Upon irradiation with ultraviolet rays, the extinction ratio of the polarizing prism was 10 ⁻⁵ , the energy density of irradiation was 1.5 J / cm ² , and the substrate was heated to 80 ° C.

A liquid crystal (Merck, Inc.) in which 1% by weight of a dichroic dye (LSB-278, manufactured by Mitsubishi Kasei Co., Ltd.) was added between the two substrates prepared by this process so as to face each other with a spacer interposed therebetween. "K-15" manufactured by K.K.) was injected.
The distance between the substrates was 10 μm. A heat treatment was performed again to manufacture a liquid crystal display element. In this liquid crystal display device, a polarizing plate was arranged on one side of the cell, the cell was rotated, the transmittance was measured, and the dichroic ratio was tested. The results are shown by ● in FIG. From FIG. 6, it can be seen that the dichroic ratio is 10 or more when the addition amount of the monomer is 20 to 75 wt%. Therefore, it can be seen that when the addition amount of the monomer is within the range of 20 to 75 wt%, the dichroic ratio is high and the liquid crystal molecules are sufficiently aligned. If 6- (4'-cyanobiphenyl) oxyhexyl acrylate was not added and an alignment film was similarly prepared using only polyvinyl cinnamate, the dichroic ratio was 5 at maximum and the contrast was low. there were.

Test Example 4 In Test Example 3 above, 6-
Using 6- (4'-cyanobiphenyl) oxyhexyl methacrylate instead of (4'-cyanobiphenyl) oxyhexyl acrylate, a test sample of a liquid crystal display device was similarly prepared, and two-color The ratio was measured. The results are shown by ◯ in FIG. From Figure 6, the amount of monomer added is 1
It can be seen that the dichroic ratio is 9 or more if it is 0 to 85 wt%, and the dichroic ratio is 10 or more if the addition amount is 20 to 75 wt%. Therefore, the amount of monomer added is 10 to 85 wt.
Within the range of%, it can be seen that the dichroic ratio is high and the liquid crystal molecules are sufficiently aligned.

[0054]

The alignment film of the present invention uses a special polymer compound material obtained by adding a 6-biphenyloxyalkyl acrylate compound to polyvinyl cinnamate, and has high photosensitivity and short time. It becomes possible to perform a sufficient alignment treatment by irradiation with polarized ultraviolet rays. Therefore, the manufacturing time can be shortened and the production cost can be reduced. In other words, if a certain irradiation time is required, the alignment regulating force of the liquid crystal can be increased and the dichroic ratio can be increased as compared with the conventional one. Further, the alignment film of the present invention has a strong interaction with the liquid crystal, can align the liquid crystal uniformly, and can suppress the generation of domains.
Further, the dielectric constant is not low, and even if a sufficient voltage is applied to the liquid crystal, the requirement for thinning the alignment film is relaxed, high accuracy is not required in the manufacturing process, and the yield can be improved.

Further, since the alignment treatment can be performed only by irradiating polarized ultraviolet rays, unlike the rubbing treatment or the like, a non-contact type can be used and generation of static electricity or mixing of impurities can be prevented. .

At this time, 6- (4 'in the polymer compound
The content of -cyanobiphenyl) oxyhexyl acrylate is preferably 10 wt% or more and 85 wt% or less, more preferably 20 wt% or more and 75 wt% or less.

Further, with the liquid crystal display device provided with the alignment film of the present invention, the manufacturing process of the alignment film can be shortened,
Further, the contrast having a high dichroic ratio is improved. Moreover, since the liquid crystal can be uniformly aligned,
The generation of domains can be suppressed. Moreover, since the manufacturing is easy, the yield can be improved.

Further, according to the method for producing an alignment film of the present invention, since the alignment treatment can be performed only by irradiating polarized ultraviolet rays, unlike the rubbing treatment or the like, a non-contact type can be used, and static electricity can be eliminated. Generation and mixing of impurities can be prevented, and productivity is improved.

Further, in addition to the irradiation of polarized ultraviolet rays, it is possible to accompany the formation of irregularities by the transfer mold, so that the alignment treatment can be performed more reliably and the dichroic ratio can be improved. Further, by using the specific polymer material of the present invention for the alignment film, it is possible to maintain a sufficient pretilt angle even when an external force or heat is applied, and it is possible to suppress the generation of domains.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a liquid crystal display element.

FIG. 2 is a perspective view showing an example of an alignment film of the present invention.

FIG. 3 is a perspective view showing an example of an alignment film of the present invention.

FIG. 4 is a partial side view of an uneven row.

FIG. 5 is a side view showing an example of an alignment film manufacturing apparatus.

FIG. 6 is a graph showing the relationship between the amount of monomer added and the dichroic ratio.

[Explanation of symbols]

 10 Liquid crystal display element 12 Substrate 14 Substrate 16 Liquid crystal 20 Transparent electrode 24 Alignment film 32 Long side part 34 Short side part 36 Convex part 52 Transfer type

Front Page Continuation (72) Inventor Shigeru Sugimori 3-6-3 Nakanoshima, Kita-ku, Osaka City, Chisso Co., Ltd. In the company

Claims (9)

[Claims] 1. An alignment film for a liquid crystal display device, comprising a polymer compound material obtained by adding 6-biphenyloxyalkyl acrylate compound having the following chemical formula to polyvinyl cinnamate. Embedded image In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group. 2. The alignment film for a liquid crystal display device according to claim 1, wherein the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material is 10 wt% or more and 85 wt% or less. 3. The alignment film for a liquid crystal display device according to claim 1, wherein the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material is 20 wt% or more and 75 wt% or less. 4. A liquid crystal display device comprising a polyvinyl cinnamate and an alignment film made of a polymer compound material to which a 6-biphenyloxyalkyl acrylate compound having the following chemical formula is added. Embedded image In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group. 5. The liquid crystal display device according to claim 4, wherein the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material forming the alignment film is 10 wt% or more and 85 wt% or less. 6. The liquid crystal display device according to claim 4, wherein the content of the 6-biphenyloxyalkyl acrylate compound in the polymer compound material forming the alignment film is 20 wt% or more and 75 wt% or less. 7. A solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula is applied on a substrate to form a film,
A method for producing an alignment film, which comprises irradiating polarized ultraviolet light to impart anisotropy to the film surface. Embedded image In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group. 8. A step of applying a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula onto a substrate to form a polymer compound film, and a long side portion and a short side portion. A transfer mold having a pressure contact surface formed by repeatedly forming a convex portion consisting of a portion is pressed against the polymer compound film, and from the long side part and the short side part on the surface of the polymer compound film. And a step of irradiating the polymer compound film with ultraviolet rays polarized in a direction substantially orthogonal to the first direction. Alignment film manufacturing method. [Chemical 4] In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group. 9. A step of applying a solution containing polyvinyl cinnamate and a 6-biphenyloxyalkyl acrylate compound having the following chemical formula onto a substrate to form a polymer compound film, long side portions and short side portions And a ridge-like concave-convex row formed by repeatedly forming convex portions consisting of parts in an arbitrary direction, and a valley that is lower in height than the ridge-like concave-convex row and is formed along the same direction as the ridge-like concave-convex row. -Shaped concave and convex rows are alternately formed adjacent to each other, the concave and convex of a repeating unit length shorter than the repeating unit length of the concave and convex formed along the arbitrary direction, in a direction substantially orthogonal to the arbitrary direction. A transfer mold having a pressure contact surface formed along the surface of the polymer compound film is pressed against the surface of the polymer compound film to form a concavo-convex row having a long repeating unit length on the surface of the polymer compound film along the first direction. And substantially orthogonal to the first direction Forming a concavo-convex array having a repeating unit length shorter than the repeating unit length of the concavo-convex array along the first direction, the ultraviolet light polarized along the second direction. And a step of irradiating the polymer compound film. Embedded image In the chemical formula, n represents an integer of 1 to 20, X represents H or an alkyl group, Y represents H, CN, F, Cl, Br, I, or an alkyl group.