WO2014148569A1 - Method for manufacturing in-plane-switching-type liquid-crystal display element - Google Patents

Abstract

Provided is an in-plane-switching-type liquid-crystal display element having excellent reliability to which an orientation control function is imparted with high efficiency. A method for manufacturing the in-plane-switching-type liquid-crystal display element having: [I] a step for forming a light-sensitive side-chain-type polymer film by applying a light-sensitive composition, containing (A) a light-sensitive side-chain-type polymer expressing liquid crystallinity within a prescribed temperature range, and (B) an organic solvent, to a substrate having a conductive film for in-plane switching; [II] a step in which polarized ultraviolet light is radiated on the light-sensitive side-chain-type polymer film to create a side-chain-type polymer film; [III] a step for heating the side-chain-type polymer film; and [IV] a step for then further radiating ultraviolet light.

Description

Method of manufacturing lateral electric field drive type liquid crystal display element

The present invention relates to a method of manufacturing a horizontal electric field drive type liquid crystal display element, and more particularly to a method of manufacturing a horizontal electric field drive type liquid crystal display element having excellent image sticking characteristics.

The liquid crystal display element is known as a light, thin, and low power consumption display device and has been remarkably developed in recent years. The liquid crystal display element is configured, for example, by sandwiching a liquid crystal layer between a pair of transparent substrates provided with electrodes. In the liquid crystal display element, an organic film made of an organic material is used as the liquid crystal alignment film so that the liquid crystal is in a desired alignment state between the substrates.

That is, the liquid crystal alignment film is a component of the liquid crystal display element, and is formed on the surface of the substrate that holds the liquid crystal in contact with the liquid crystal, and plays a role of aligning the liquid crystal in a certain direction between the substrates. The liquid crystal alignment film may be required to play a role of controlling the pretilt angle of the liquid crystal in addition to the role of aligning the liquid crystal in a certain direction such as a direction parallel to the substrate. In such a liquid crystal alignment film, the ability to control the alignment of liquid crystal (hereinafter referred to as alignment control ability) is given by performing an alignment treatment on the organic film constituting the liquid crystal alignment film.

As a method for aligning a liquid crystal alignment film for imparting alignment control ability, a rubbing method has been conventionally known. The rubbing method is a method of rubbing (rubbing) the surface of an organic film such as polyvinyl alcohol, polyamide or polyimide on a substrate with a cloth such as cotton, nylon or polyester in the rubbing direction (rubbing direction). This is a method of aligning liquid crystals. Since this rubbing method can easily realize a relatively stable alignment state of liquid crystals, it has been used in the manufacturing process of conventional liquid crystal display elements. As an organic film used for the liquid crystal alignment film, a polyimide-based organic film excellent in reliability such as heat resistance and electrical characteristics has been mainly selected.

However, in the rubbing method of rubbing the surface of the liquid crystal alignment film made of polyimide or the like, generation of dust and static electricity may be a problem. In addition, due to the high definition of the liquid crystal surface element in recent years and the unevenness caused by the corresponding electrodes on the substrate and the switching active element for driving the liquid crystal, the surface of the liquid crystal alignment film cannot be uniformly rubbed with a cloth. In some cases, alignment of the liquid crystal cannot be realized.

Therefore, a photo-alignment method has been actively studied as another alignment treatment method for a liquid crystal alignment film that is not rubbed.
There are various photo alignment methods. In this method, anisotropy is formed in the organic film constituting the liquid crystal alignment film by linearly polarized light or collimated light, and the liquid crystal is aligned according to the anisotropy. A decomposition type photo-alignment method is known as a main photo-alignment method. For example, irradiate a polyimide film with polarized UV light, cause anisotropic decomposition by utilizing the polarization direction dependency of UV absorption of the molecular structure, and align the liquid crystal with the remaining polyimide without decomposition. The method of making is known (for example, refer patent document 1).

Further, photocrosslinking type and photoisomerization type photo-alignment methods are also known. For example, polyvinyl cinnamate is used and irradiated with polarized ultraviolet rays to cause a dimerization reaction (crosslinking reaction) at the double bond portion of two side chains parallel to the polarized light. Then, the liquid crystal is aligned in a direction perpendicular to the polarization direction (see, for example, Non-Patent Document 1). In addition, when a side chain polymer having azobenzene in the side chain is used, irradiation with polarized ultraviolet light causes an isomerization reaction at the azobenzene portion of the side chain parallel to the polarized light, and the liquid crystal is aligned in a direction perpendicular to the polarization direction. Align (for example, see Non-Patent Document 2).

As in the above example, the liquid crystal alignment film alignment treatment method by the photo alignment method does not require rubbing, and there is no fear of generation of dust or static electricity. An alignment process can be performed even on a substrate of a liquid crystal display element having an uneven surface, which is a method for aligning a liquid crystal alignment film suitable for an industrial production process.

Japanese Patent No. 3893659

As described above, the photo-alignment method eliminates the rubbing process itself as compared with the rubbing method that has been industrially performed as an alignment treatment method for liquid crystal display elements, and thus has a great advantage. And compared with the rubbing method in which the alignment control ability becomes almost constant by rubbing, the photo alignment method can control the alignment control ability by changing the irradiation amount of polarized light. However, in the photo-alignment method, in order to achieve the same degree of alignment control ability as in the rubbing method, a large amount of polarized light irradiation may be required or stable liquid crystal alignment may not be realized. .

For example, in the decomposition type photo-alignment method described in Patent Document 1, it is necessary to irradiate a polyimide film with ultraviolet light from a high-pressure mercury lamp with an output of 500 W for 60 minutes, for example, for a long time and a large amount of ultraviolet irradiation. Further, even in the case of a dimerization type or photoisomerization type photo-alignment method, a large amount of ultraviolet irradiation of about several J (joule) to several tens of J may be required. Furthermore, in the case of the photo-crosslinking type or photoisomerization type photo-alignment method, since the thermal stability and light stability of the liquid crystal alignment are inferior, there is a problem that alignment failure or display burn-in occurs when a liquid crystal display element is used. was there. In particular, in a horizontal electric field drive type liquid crystal display element, since liquid crystal molecules are switched in a plane, alignment misalignment of liquid crystal after liquid crystal driving is likely to occur, and display burn-in caused by AC driving is a major issue. Therefore, in the photo-alignment method, there is a demand for higher efficiency of alignment treatment and realization of stable liquid crystal alignment, and liquid crystal alignment films and liquid crystals that can impart high alignment control ability to the liquid crystal alignment film with high efficiency. There is a need for aligning agents.

An object of the present invention is to provide a lateral electric field drive type liquid crystal display element which is imparted with high efficiency and orientation control ability and excellent in reliability.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have developed a photosensitive side chain polymer that exhibits liquid crystallinity in a predetermined temperature range on a substrate having a conductive film for driving a lateral electric field. The present invention has been completed by finding that it is achieved by applying a lateral electric field driving type liquid crystal display element to which an alignment control ability is imparted by applying a photosensitive composition containing, and then applying ultraviolet light irradiation and subsequent heating. The present invention has the following gist.

1. [I] On a substrate having a conductive film for lateral electric field driving,
(A) A photosensitive side chain polymer that exhibits liquid crystallinity in a temperature range of 100 to 250 ° C., and (B) a photosensitive side chain polymer that is coated with a photosensitive composition containing an organic solvent. Forming a film;
[II] a step of irradiating the photosensitive side chain polymer film with polarized ultraviolet rays;
[III] A step of heating the side chain polymer film,
[IV] A method of manufacturing a lateral electric field drive type liquid crystal display element, further comprising a step of further irradiating ultraviolet rays.

2. The amount of UV irradiation in step [II] maximizes ΔA, which is the difference between the UV absorbance in the direction parallel to the polarization direction of the polarized UV light and the UV absorbance in the direction perpendicular to the polarization direction of the polarized UV light. 2. The production method according to 1 above, which is in the range of 1% to 70% of the ultraviolet irradiation amount.
3. 3. The production method according to 1 or 2 above, wherein the ultraviolet irradiation amount in the step [II] is in the range of 1% to 50% of the ultraviolet irradiation amount that maximizes the ΔA.
4). The heating temperature in the step [III] is a temperature in the range from a temperature 10 ° C. lower than the lower limit of the temperature range in which the side chain polymer film exhibits liquid crystallinity to a temperature 10 ° C. lower than the upper limit of the temperature range. 4. The production method according to any one of 1 to 3.
5. The above 1 wherein the photosensitive group contained in the photosensitive side chain polymer exhibiting liquid crystallinity is azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan, phenylbenzoate, or a derivative thereof. 5. A method for producing a liquid crystal alignment film according to any one of 4 to 4.
6). 6. The production method according to any one of 1 to 5 above, wherein the ultraviolet irradiation amount in the step [IV] is an irradiation amount with which 20 mol or more reacts with respect to 100 mol of the photosensitive group of the side chain polymer film.
7). 7. The production method according to any one of 1 to 6, wherein the step [IV] is performed after the production of the liquid crystal display element.
8). 8. The production method according to any one of 1 to 7 above, wherein the component (A) has a side chain that undergoes photocrosslinking, photoisomerization, or photofleece transition.

9. The production according to any one of 1 to 8 above, wherein the component (A) has a side chain polymer having at least one photosensitive side chain selected from the group consisting of formulas (1) to (13) described later. Method.
10. (1) The above-mentioned 1 to (A) component has a side chain polymer having at least one liquid crystalline side chain selected from the group consisting of formulas (5) to (8) and (14) to (22) described later 10. The production method according to any one of 9 above.

11. (A) a photosensitive side-chain polymer that exhibits liquid crystallinity in a temperature range of 100 to 250 ° C., and (B) a photosensitive composition containing an organic solvent,
[I] A step of coating the photosensitive composition on a substrate having a conductive film for driving a lateral electric field to form a photosensitive side chain polymer film, [II] The photosensitive side chain polymer film A step of irradiating polarized ultraviolet rays, [III] a step of heating the side chain polymer film, and [IV] a step of irradiating the side chain polymer film with ultraviolet rays in this order. Photosensitive composition used in a method for producing a liquid crystal display device.
12 12. The photosensitive composition as described in 11 above, wherein the component (A) has a side chain that causes photocrosslinking, photoisomerization, or photofleece transition.
13. 12. The photosensitive composition according to 11 above, wherein the component (A) is a side chain polymer having at least one photosensitive side chain selected from the group consisting of formulas (1) to (13) described later.

14 The photosensitive composition according to claim 11, wherein the component (A) has at least one liquid crystalline side chain selected from the group consisting of formulas (5) to (8) and formulas (14) to (22) described later. object.
15. 11. A liquid crystal display device manufactured by the method for manufacturing a liquid crystal display device according to any one of 1 to 10 above.

Since the lateral electric field drive type liquid crystal display device manufactured by the method of the present invention is provided with the alignment control ability with high efficiency, the display characteristics are not impaired even if it is continuously driven for a long time.

It is a figure of one example which illustrates typically the introduction process of the anisotropy in the manufacturing method of the liquid crystal aligning film used for this invention, using the crosslinkable organic group for the photosensitive side chain, and introduced the anisotropic It is a figure when property is small. It is a figure of one example which illustrates typically the introduction process of the anisotropy in the manufacturing method of the liquid crystal aligning film used for this invention, using the crosslinkable organic group for the photosensitive side chain, and introduced the anisotropic It is a figure when the property is large. It is a figure of one example which illustrates typically the introduction processing of anisotropy in the manufacturing method of the liquid crystal aligning film used for the present invention, using the organic group which causes fleece transition or isomerization to the photosensitive side chain, and is introduced. It is a figure in case the anisotropy made is small. It is a figure of one example which illustrates typically the introduction processing of anisotropy in the manufacturing method of the liquid crystal aligning film used for the present invention, using the organic group which causes fleece transition or isomerization to the photosensitive side chain, and is introduced. It is a figure in case the anisotropy made is large.

As a result of intensive studies, the inventor has obtained the following knowledge and completed the present invention.
The photosensitive composition used in the production method of the present invention has a photosensitive side chain polymer (hereinafter also referred to as a side chain polymer) that can exhibit liquid crystallinity, and the photosensitive composition. A film obtained by using a product is a film of a photosensitive side chain type polymer that can exhibit liquid crystallinity. Without subjecting this film to rubbing treatment, alignment treatment can be performed by irradiation of polarized light to form a liquid crystal alignment film. That is, a film (liquid crystal alignment film) to which alignment control ability is imparted is obtained through a step of heating the side chain polymer film after irradiation of polarized light on the side chain polymer film. At this time, the slight anisotropy developed by the irradiation of polarized light becomes a driving force, and the liquid crystalline side chain polymer itself is efficiently reoriented by self-organization. As a result, a highly efficient alignment process can be realized as the liquid crystal alignment film, and a liquid crystal alignment film with high alignment control ability can be obtained. Thereafter, the unreacted photosensitive groups can be reduced by irradiating the liquid crystal alignment film with ultraviolet rays. By doing so, it is possible to obtain a liquid crystal display element with excellent reliability while maintaining highly efficient alignment control ability.

<Method for manufacturing liquid crystal display element>
Hereafter, each process of process [I]-process [IV] in the manufacturing method of this invention is demonstrated.
In the step [I], a photosensitive composition containing a photosensitive side chain polymer that exhibits liquid crystallinity in a predetermined temperature range and an organic solvent on a substrate having a conductive film for driving a lateral electric field (hereinafter, (Also referred to as a photosensitive composition) to form a polymer film. The substrate is not particularly limited, and for example, a transparent substrate such as a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate. In consideration of application of the obtained polymer film, it is also possible to use a substrate on which ITO (Indium Tin Oxide) electrodes for driving liquid crystals are formed in order to simplify the process of manufacturing liquid crystal display elements. is there. In consideration of application to a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used, and a light reflecting material such as aluminum can be used as an electrode in this case.

Application method is not particularly limited, but industrially, a method of screen printing, offset printing, flexographic printing, an inkjet method or the like is common. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method (rotary coating method), or a spray method, and these may be used depending on the purpose.

After the photosensitive composition is applied on the substrate, the solvent is evaporated at 20 to 180 ° C., preferably 40 to 150 ° C. by a heating means such as a hot plate, a thermal circulation oven, or an IR (infrared) oven, and the photosensitive composition is exposed. Can be obtained. The drying temperature at this time is preferably lower than the liquid crystal phase expression temperature of the side chain polymer. If the thickness of the polymer film is too thick, it will be disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered, so it is preferably 5 to 300 nm, more preferably 10 to 10 nm. 150 nm.
In addition, it is also possible to provide the process of cooling the board | substrate with which the photosensitive side chain type polymer film was formed to room temperature after process [I] and before the following process [II].

In step [II], the photosensitive side chain polymer film obtained in step [I] is irradiated with polarized ultraviolet rays. When irradiating the surface of the photosensitive side chain polymer film with polarized ultraviolet rays, the substrate is irradiated with polarized ultraviolet rays through a polarizing plate from a certain direction. As the ultraviolet rays to be used, ultraviolet rays having a wavelength in the range of 200 to 400 nm can be used. Preferably, the optimum wavelength is selected through a filter or the like depending on the type of the photosensitive side chain polymer film to be used. For example, ultraviolet light having a wavelength in the range of 290 to 400 nm can be selected and used so that the photocrosslinking reaction can be selectively induced. As the ultraviolet light, for example, light emitted from a high-pressure mercury lamp can be used.

Regarding the irradiation amount of polarized ultraviolet rays, the maximum value of ΔA which is the difference between the ultraviolet absorbance in the direction parallel to the polarization direction of the polarized ultraviolet rays and the ultraviolet absorbance in the direction perpendicular to the polarization direction of the polarized ultraviolet rays in the photosensitive side chain polymer film to be used. (Hereinafter also referred to as ΔAmax) is preferably in the range of 1% to 70%, more preferably in the range of 1 to 50% of the amount of polarized ultraviolet light that realizes (hereinafter also referred to as ΔAmax).

In step [III], the side chain polymer film irradiated with the ultraviolet light polarized in step [II] is heated. For the heating, a heating means such as a hot plate, a heat circulation type oven or an IR (infrared) type oven is used. The heating temperature can be determined in consideration of the temperature at which the liquid crystallinity of the side chain type polymer film to be used is developed. In general, since the intermolecular force is small on the surface of the film, the surface Tg (glass transition temperature) is lower than the bulk Tg, that is, even in the liquid crystal temperature range of the liquid crystal alignment film surface. It is expected to be lower than the liquid crystal temperature range seen in bulk. That is, the heating temperature after irradiation with polarized ultraviolet rays is 10 ° C. lower than the lower limit of the liquid crystal temperature range in which the side chain polymer film used exhibits liquid crystallinity, and 10 ° C. lower than the upper limit of the liquid crystal temperature range. It is preferable that it is the temperature of the range made into an upper limit.
By having the above steps, the present invention achieves highly efficient introduction of anisotropy into the photosensitive side chain polymer film. And the board | substrate with a liquid crystal aligning film used for the manufacturing method of this invention can be manufactured highly efficiently.

In step [IV], the side chain polymer film obtained in step [III] is further irradiated with ultraviolet rays. In this step, the side chain polymer film on the substrate may be directly irradiated with ultraviolet rays immediately after the step [III], and then the liquid crystal display element using the substrate with the side chain polymer film is used. Ultraviolet rays may be irradiated in the step of manufacturing the liquid crystal display device, or after the liquid crystal display device is manufactured, the obtained liquid crystal display device may be irradiated with ultraviolet rays. By doing in this way, since the unreacted photosensitive group can be quenched while the alignment control ability is imparted with high efficiency, it becomes possible to manufacture a liquid crystal display element having excellent reliability. The liquid crystal temperature range in the present invention is a value obtained by differential scanning calorimetry.

<Photosensitive composition>
The photosensitive composition used in the production method of the present invention includes a photosensitive side chain polymer that can exhibit liquid crystallinity, and a photosensitive side chain polymer that exhibits liquid crystallinity in a predetermined temperature range. Including. And the side chain which has photosensitivity has couple | bonded with the principal chain, A crosslinking reaction, an isomerization reaction, or a light fleece rearrangement can be caused in response to light. The structure of the side chain having photosensitivity is not particularly limited, but a structure that undergoes a crosslinking reaction or photofleece rearrangement in response to light is desirable, and a structure that causes a crosslinking reaction is more desirable. In this case, the achieved orientation control ability can be stably maintained for a long period of time even when exposed to external stress such as heat.

The structure of the photosensitive side chain polymer film capable of exhibiting liquid crystallinity is not particularly limited as long as it satisfies such characteristics, but it is preferable to have a rigid mesogenic component in the side chain structure. In this case, stable liquid crystal alignment can be obtained when the side chain polymer film is used as a liquid crystal alignment film. The structure of the side chain polymer has, for example, a main chain and a side chain bonded to the main chain, and the side chain is a mesogenic component such as a biphenyl group, a terphenyl group, a phenylcyclohexyl group, a phenylbenzoate group, or an azobenzene group. And a photosensitive group bonded to the tip and capable of undergoing a crosslinking reaction or an isomerization reaction in response to light. Moreover, it can be set as the structure which has a phenylbenzoate group which has a main chain and the side chain couple | bonded with it, the side chain also becomes a mesogenic component, and carries out a photo-Fries rearrangement reaction.

More specific examples of the structure of the photosensitive side chain polymer that can exhibit liquid crystallinity include at least one selected from the group consisting of hydrocarbon, acrylate, methacrylate, maleimide, norbornene, and siloxane. A structure having a main chain and at least one photosensitive side chain selected from the group consisting of the following formulas (1) to (13) is preferable.

However, A, B, and D each independently represent a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. A ′ and B ′ are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, Or, —O—CO—CH═CH— is represented. Y ₁ is a group selected from a monovalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and a hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl or alkoxy group having 1 to 4 carbon atoms. X represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, l represents an integer of 1 to 12, and m represents an integer of 0 to 2 M1 and m2 each independently represents an integer of 1 to 3, and n represents an integer of 0 to 12 (provided that B is a single bond when n = 0). Y ₂ is a group selected from a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and the hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. R represents OH, NH ₂ , an alkoxy group having 1 to 6 carbon atoms or an alkylamino group having 1 to 6 carbon atoms. R ₁ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl or alkoxy group having 1 to 12 carbon atoms. One or more of the benzene rings in the formulas (1) to (13) may be substituted with the same or different rings selected from a naphthalene ring, an anthracene ring and a fluorene ring.
The side chains represented by the above formulas (1) to (13) have a structure having groups such as biphenyl, terphenyl, phenylcyclohexyl, phenylbenzoate, azobenzene, naphthalene, anthracene, and fluorene as mesogenic components. And at the tip, it has a photosensitive group that undergoes a dimerization reaction in response to light and undergoes a crosslinking reaction, or has a main chain and a side chain bonded thereto, and the side chain also becomes a mesogenic component. And having at least one of phenylbenzoate groups that undergo a photo-Fries rearrangement reaction.

In the production method of the present invention, a photosensitive side chain type polymer film is formed on a substrate using a photosensitive composition, and then irradiated with polarized ultraviolet rays. Next, by heating, high-efficiency anisotropy is introduced into the side chain polymer film, and a substrate with a liquid crystal alignment film having a liquid crystal alignment control ability is manufactured. Side-chain polymer membranes utilize the principle of molecular reorientation induced by side-chain photoreaction and self-organization based on liquid crystallinity to provide highly efficient anisotropy to side-chain polymer membranes. Realize the introduction. In the present invention, in the case of a structure having a photocrosslinkable group as a photosensitive group in the side chain polymer, after forming the photosensitive side chain polymer film on the substrate using the photosensitive side chain polymer. After irradiating polarized ultraviolet rays and then heating, a liquid crystal display element is manufactured.

Hereinafter, a first embodiment using a side chain polymer having a structure having a photocrosslinkable group as a photosensitive group, a side chain polymer having a structure having a photofleece rearrangement group or a group causing isomerization as a photosensitive group. A second embodiment using the above will be described.

FIG. 1 schematically shows an anisotropy introduction process in a method for producing a liquid crystal alignment film using a side chain polymer having a photocrosslinkable group as a photosensitive group in the first embodiment of the present invention. An example to explain is shown. In particular, when the introduced anisotropy is small, that is, in the first embodiment of the present invention, the ultraviolet irradiation amount in the step [II] is in the range of 1 to 15% of the ultraviolet irradiation amount that maximizes ΔA. It is a schematic diagram in the case.
FIG. 1A is a diagram schematically showing the state of the side chain polymer film 1 before polarized light irradiation, and has a structure in which the side chains 2 are randomly arranged. According to the random arrangement of the side chain 2, the mesogenic component and the photosensitive group of the side chain 2 are also randomly oriented, and the side chain type polymer film 1 is isotropic.
FIG. 1 (b) is a diagram schematically showing the state of the side chain polymer film 1 after irradiation with polarized light. The photosensitive groups in the side chain 2 arranged in a direction parallel to the polarization direction of ultraviolet rays are shown. The photosensitive group of the side chain 2a possessed preferentially causes a photoreaction such as a dimerization reaction. As a result, the density of the side chain 2a that has undergone photoreaction becomes slightly higher in the polarization direction of the irradiated ultraviolet rays, and as a result, the side chain polymer film 1 is provided with very small anisotropy.
FIG. 1C is a diagram schematically showing the state of the side chain polymer film 1 after heating. In the side chain polymer film 1, the direction perpendicular to the direction parallel to the polarization direction of the irradiated ultraviolet light is shown. The amount of the cross-linking reaction that occurs. In this case, since the amount of the crosslinking reaction generated in the direction parallel to the polarization direction of the irradiated ultraviolet ray is very small, this crosslinking reaction site functions as a plasticizer. Therefore, the liquid crystallinity in the direction perpendicular to the polarization direction of the irradiated ultraviolet light is higher than the liquid crystallinity in the parallel direction, and the side chain 2 containing the mesogenic component is reoriented by self-organizing in the direction parallel to the polarization direction of the irradiated ultraviolet light. As a result, the very small anisotropy of the side chain polymer film 1 induced by the photocrosslinking reaction is amplified by heat, and a larger anisotropy is given to the side chain polymer film 1. Become.

FIG. 2 schematically shows an anisotropic introduction process in the method for producing a liquid crystal alignment film using a side chain polymer having a structure having a photocrosslinkable group as a photosensitive group in the first embodiment of the present invention. An example to explain is shown. In particular, when the introduced anisotropy is large, that is, in the first embodiment of the present invention, the ultraviolet irradiation amount in the step [II] is in the range of 15 to 70% of the ultraviolet irradiation amount that maximizes ΔA. It is a schematic diagram in the case.
FIG. 2A is a diagram schematically showing the state of the side chain polymer film 3 before polarized light irradiation, and has a structure in which the side chains 4 are randomly arranged. According to the random arrangement of the side chain 4, the mesogenic component and the photosensitive group of the side chain 4 are also randomly oriented, and the side chain type polymer film 3 is isotropic.
FIG. 2 (b) is a diagram schematically showing the state of the side chain polymer film 3 after irradiation with polarized light. The photosensitive groups in the side chains 4 arranged in a direction parallel to the polarization direction of ultraviolet rays are shown. The photosensitive group of the side chain 4a possessed preferentially causes a photoreaction such as a dimerization reaction. As a result, the density of the side chain 4a that has undergone photoreaction increases in the polarization direction of the irradiated ultraviolet rays, and as a result, a small anisotropy is imparted to the side chain type polymer film 3.
FIG. 2 (c) is a diagram schematically showing the state of the side chain polymer film 3 after heating. In the side chain polymer film 3, the direction perpendicular to the direction parallel to the polarization direction of the irradiated ultraviolet light The amount of the cross-linking reaction that occurs. Therefore, the side chain 4 containing the mesogenic component is reoriented by self-organizing in a direction parallel to the polarization direction of the irradiated ultraviolet light. As a result, the small anisotropy of the side chain polymer film 3 induced by the photocrosslinking reaction is amplified by heat, and a larger anisotropy is given to the side chain polymer film 3.

FIG. 3 shows a liquid crystal alignment film using a side chain type polymer having a structure having a light Fleece rearrangement group represented by the above formula (5) or (7) as a photosensitive group in the second embodiment of the present invention. It is a figure of one example which illustrates typically the introduction process of anisotropy in this manufacturing method. In particular, when the introduced anisotropy is small, that is, in the second embodiment of the present invention, the ultraviolet irradiation amount in the step [II] is in the range of 1 to 15% of the ultraviolet irradiation amount that maximizes ΔA. It is a schematic diagram in the case.
FIG. 3A is a diagram schematically showing the state of the side chain polymer film 5 before irradiation with polarized light, and has a structure in which the side chains 6 are randomly arranged. According to the random arrangement of the side chain 6, the mesogenic component and the photosensitive group of the side chain 6 are also randomly oriented, and the side chain polymer film 5 is isotropic.
FIG. 3B is a diagram schematically showing the state of the side chain polymer film 5 after irradiation with polarized light. The photosensitive groups in the side chains 6 arranged in a direction parallel to the polarization direction of ultraviolet rays are shown. The photosensitive group of the side chain 6a has preferentially photoreaction such as photofleece rearrangement. As a result, the density of the side chain 6a subjected to the photoreaction becomes slightly higher in the polarization direction of the irradiated ultraviolet rays, and as a result, the side chain type polymer film 5 is given a very small anisotropy.
FIG. 3C is a diagram schematically showing the state of the side chain polymer film 5 after heating. In the side chain polymer film 5, the direction perpendicular to the direction parallel to the polarization direction of the irradiated ultraviolet rays. And the amount of photo-Fries rearrangement reaction that occurs. In this case, since the liquid crystal alignment force of the light fleece rearrangement generated in the direction perpendicular to the polarization direction of the irradiated ultraviolet light is stronger than the liquid crystal alignment force of the side chain before the reaction, it is self-organized in the direction perpendicular to the polarization direction of the irradiated ultraviolet light. The side chain 6 containing the mesogenic component is reoriented. As a result, the very small anisotropy of the side chain polymer film 5 induced by the photofleece rearrangement reaction is amplified by heat, and a larger anisotropy is given to the side chain polymer film 5. become.

FIG. 4 shows a liquid crystal alignment film using a side chain polymer having a structure having a photo-Fries rearrangement group represented by the above formula (6) or (8) as a photosensitive group in the second embodiment of the present invention. It is a figure of one example which illustrates typically the introduction process of anisotropy in this manufacturing method. In particular, when the introduced anisotropy is large, that is, in the second embodiment of the present invention, the ultraviolet irradiation amount in the step [II] is within the range of 15% to 70% of the ultraviolet irradiation amount that maximizes ΔA. It is a schematic diagram in a case.
FIG. 4A is a diagram schematically showing a state of the side chain polymer film 7 before irradiation with polarized light, and has a structure in which the side chains 8 are randomly arranged. According to the random arrangement of the side chain 8, the mesogenic component and the photosensitive group of the side chain 8 are also randomly oriented, and the side chain polymer film 7 is isotropic.
FIG. 4B is a diagram schematically showing the state of the side chain polymer film 7 after irradiation with polarized light. The photosensitive groups in the side chains 8 arranged in a direction parallel to the polarization direction of ultraviolet rays are shown. The photosensitive group of the side chain 8a has a photoreaction such as photofleece rearrangement preferentially. As a result, the density of the side chain 8 a that has undergone photoreaction increases in the polarization direction of the irradiated ultraviolet light, and as a result, a small anisotropy is imparted to the side chain type polymer film 7.
FIG. 4C is a diagram schematically showing the state of the side chain polymer film 7 after heating. In the side chain polymer film 7, the direction perpendicular to the direction parallel to the polarization direction of the irradiated ultraviolet rays. And the amount of photo-Fries rearrangement reaction that occurs. Since the anchoring force of the optical fleece rearrangement 8a is stronger than that of the side chain 8 before the rearrangement, if a certain amount or more of the optical fleece rearrangement is generated, it self-assembles in a direction parallel to the polarization direction of the irradiated ultraviolet light, and the mesogenic component is formed. The containing side chain 8 is reoriented. As a result, the small anisotropy of the side chain polymer film 7 induced by the photofleece rearrangement reaction is amplified by heat, and a larger anisotropy is given to the side chain polymer film 7. .
Therefore, the side chain polymer film is a liquid crystal alignment with high anisotropy introduced and high alignment control ability by sequentially irradiating the side chain polymer film with polarized ultraviolet rays and heat treatment. It can be a membrane.
In the side chain polymer film, the irradiation amount of polarized ultraviolet rays to the side chain polymer film and the heating temperature in the heat treatment are optimized. Thereby, introduction of anisotropy into the side chain type polymer film can be realized with high efficiency.

The inventor obtained the following knowledge as a result of intensive studies. That is, the optimum irradiation amount of polarized ultraviolet rays for introducing highly efficient anisotropy into the side chain polymer film is such that the photo-sensitive group in the side chain polymer film undergoes photocrosslinking reaction or photoisomerization reaction, or It corresponds to the irradiation amount of polarized ultraviolet rays that optimizes the amount of photofleece rearrangement reaction. As a result of irradiating the side chain type polymer film with polarized ultraviolet rays, if there are few photogroups in the side chain that undergoes photocrosslinking reaction, photoisomerization reaction, or photofleece rearrangement reaction, the amount of photoreaction is not sufficient. In that case, sufficient self-organization does not proceed even after heating. On the other hand, when the structure having a photocrosslinkable group is irradiated with polarized ultraviolet rays in the side chain type polymer film, if the photopolymer of the side chain undergoing the crosslink reaction becomes excessive, the crosslink reaction between the side chains is caused. Too much progress. In that case, the obtained side chain type polymer film becomes rigid and may hinder the progress of self-assembly by subsequent heating. In addition, when the side chain type polymer film is irradiated with polarized ultraviolet rays to the structure having the light fleece rearrangement group, the side chain type polymer film becomes excessive if the side chain photosensitive group that undergoes the light fleece rearrangement reaction becomes excessive. The liquid crystallinity of the film will be too low. In that case, the liquid crystallinity of the obtained side chain polymer film is also lowered, which may hinder the progress of self-assembly by subsequent heating. Furthermore, when irradiating polarized ultraviolet light to a structure having a photo-fleece rearrangement group, if the amount of ultraviolet light irradiation is too large, the side-chain polymer is photodegraded, preventing the subsequent self-organization by heating. It may become.

Therefore, in the side chain polymer film, the optimum amount of the photopolymerization reaction, photoisomerization reaction, or photofleece rearrangement reaction of the photosensitive group of the side chain by irradiation with polarized ultraviolet rays is the same as that of the side chain polymer film. The content is preferably 0.1 mol% to 40 mol%, more preferably 0.1 mol% to 20 mol% of the photosensitive group. By making the amount of the photo-reactive side chain photosensitive group within such a range, the self-organization in the subsequent heat treatment proceeds efficiently, and the formation of highly efficient anisotropy in the film is possible. Become.

For side-chain polymer films, the amount of photo-crosslinking reaction, photoisomerization reaction, or photofleece rearrangement reaction of photosensitive groups in the side chain of the side-chain polymer film by optimizing the irradiation amount of polarized ultraviolet rays To optimize. In combination with the subsequent heat treatment, high-efficiency introduction of anisotropy into the side chain polymer film is realized. In that case, a suitable amount of polarized ultraviolet light can be determined based on the evaluation of ultraviolet absorption of the side chain polymer film.

That is, the UV absorption in the direction parallel to the polarization direction of the polarized UV light and the UV absorption in the vertical direction after the irradiation with the polarized UV light are measured for the side chain type polymer film. From the measurement result of ultraviolet absorption, ΔA, which is the difference between the ultraviolet absorbance in the direction parallel to the polarization direction of polarized ultraviolet rays and the ultraviolet absorbance in the direction perpendicular to the polarization direction of the polarized ultraviolet rays, is evaluated. Then, the maximum value (ΔAmax) of ΔA realized in the side chain type polymer film and the irradiation amount of polarized ultraviolet rays that realizes it are obtained. In the production method of the present invention, a preferable amount of polarized ultraviolet rays to be irradiated in the production of the liquid crystal alignment film can be determined on the basis of the amount of polarized ultraviolet rays to realize this ΔAmax.

In the production method of the present invention, the irradiation amount of the polarized ultraviolet rays on the side chain polymer film is preferably in the range of 1% to 70% of the amount of the polarized ultraviolet rays that realizes ΔAmax. % Is more preferable. In the side chain polymer film, the irradiation amount of polarized ultraviolet light within the range of 1% to 50% of the amount of polarized ultraviolet light that realizes ΔAmax is 0.1% of the entire photosensitive group of the side chain polymer film. The mol% to 20 mol% corresponds to the amount of polarized ultraviolet light that undergoes a photocrosslinking reaction.

Next, in the production method of the present invention, the side chain polymer film is heated after being irradiated with polarized ultraviolet rays. This side chain type polymer film is a polymer film that can exhibit liquid crystallinity in a predetermined temperature range. The heat treatment after irradiation with polarized ultraviolet rays can be determined based on the temperature at which the liquid crystallinity of the side chain polymer film is developed. In addition, the temperature at which the surface of the side chain polymer film develops liquid crystallinity is expected to be lower than the temperature at which liquid crystallinity develops when viewed in bulk. That is, the heating temperature after irradiation with polarized ultraviolet rays is 10 ° C. from the temperature range 10 ° C. lower than the temperature range in which the side chain polymer film exhibits liquid crystallinity (hereinafter also referred to as the liquid crystal temperature range). A temperature in the range up to a low temperature is preferred.

The side chain type polymer film used in the present invention is heated after being irradiated with polarized ultraviolet rays to be in a liquid crystal state, and is self-organized and reoriented in a direction parallel to the polarization direction. As a result, the small anisotropy of the side chain polymer film induced by the photocrosslinking reaction, photoisomerization reaction, and photofleece rearrangement reaction is amplified by heat. However, even when the side chain polymer film is in a liquid crystal state by heating, if the heating temperature is low, the viscosity of the side chain polymer film in the liquid crystal state is high and realignment due to self-assembly is less likely to occur. End up. For example, when the heating temperature is lower by 10 ° C. or more from the lower limit of the liquid crystal temperature range of the side chain polymer film, the effect of anisotropy amplification by heat in the side chain polymer film may be sufficient. Can not.

Even if the side chain polymer film is in a liquid crystal state by heating, when the heating temperature is high, the state of the side chain polymer film becomes close to an isotropic liquid state, and the side chain polymer film is made uniform by self-organization. It becomes difficult to reorient in the direction. For example, when the heating temperature is higher than the temperature lower by 10 ° C. from the upper limit of the liquid crystal temperature range of the side chain polymer film, the anisotropy amplification effect due to heat in the side chain polymer film is sufficient. I can't.

As described above, in the present invention, in order to achieve highly efficient anisotropy introduction into the side chain polymer film, a suitable heating temperature is determined based on the liquid crystal temperature range of the side chain polymer film. As described above, the heating temperature after irradiation with polarized ultraviolet rays is 10 ° C. lower than the lower limit of the liquid crystal temperature range of the side chain polymer film, and the upper limit is 10 ° C. lower than the upper limit of the liquid crystal temperature range. The temperature is within the range. Therefore, for example, when the liquid crystal temperature range of the side chain polymer film is 100 to 200 ° C., the heating temperature after irradiation with polarized ultraviolet light is desirably 90 to 190 ° C. By so doing, greater anisotropy is imparted to the side chain polymer film. By doing so, the obtained liquid crystal display element shows high reliability against external stresses such as light and heat.

The photosensitive composition used in the present invention contains a side chain polymer that reacts with light in a wavelength range of 250 to 400 nm and exhibits liquid crystallinity in a temperature range of 100 to 250 ° C. The polymer serving as a component of the photosensitive composition preferably has a photosensitive group that reacts with light in the wavelength range of 250 to 400 nm. The polymer as a component of the photosensitive composition preferably has a mesogenic group in order to exhibit liquid crystallinity in a certain temperature range of 100 to 250 ° C.
The above-mentioned photosensitive side chain polymer capable of exhibiting liquid crystallinity can be obtained by polymerizing the above photosensitive side chain monomer and / or liquid crystalline side chain monomer having the above photosensitive group.

[Photosensitive side chain monomer]
The photosensitive side chain monomer is a monomer having a photosensitive group at a side chain portion of a polymer when a polymer is formed. As the photosensitive group possessed by the side chain, the following structures or derivatives thereof are preferable.

More specific examples of the photosensitive side chain monomer include a main chain composed of at least one selected from the group consisting of hydrocarbon, (meth) acrylate, maleimide, norbornene and siloxane, and the following formula (1): A structure having at least one photosensitive side chain selected from the group consisting of (13) to (13) is preferable.

In the above formulas (1) to (13), A, B, and D are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—. Represents. A ′ and B ′ are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, Or, —O—CO—CH═CH— is represented. Y ₁ is a group selected from a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and the hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. X is a single bond,
—COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, l represents an integer of 1 to 12, m represents an integer of 0 to 2, m1, m2 independently represents an integer of 1 to 3, and n represents an integer of 0 to 12 (provided that when n = 0, B is a single bond). Y ₂ is a group selected from a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and the hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. R represents —OH, —NH ₂ , an alkoxy group having 1 to 6 carbon atoms or an alkylamino group having 1 to 6 carbon atoms. R ₁ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. One or more of the benzene rings in the formulas (1) to (8) may be substituted with the same or different rings selected from a naphthalene ring, an anthracene ring and a fluorene ring.

[Liquid crystalline side chain monomer]
The liquid crystalline side chain monomer is a monomer in which the polymer exhibits liquid crystallinity and has a mesogenic group at the side chain portion of the polymer. As the mesogenic group possessed by the side chain, biphenyl, phenylbenzoate, or the like alone may have a mesogen structure, or a side chain may form a mesogen structure by hydrogen bonding, such as benzoic acid. As the mesogenic group possessed by the side chain, the following structure is preferable.

Furthermore, as a more specific example of the liquid crystalline side chain monomer, a main chain composed of at least one selected from the group consisting of hydrocarbon, (meth) acrylate, maleimide, norbornene and siloxane, and the following formula ( A structure having at least one liquid crystalline side chain selected from the group consisting of 5) to (8) and (14) to (22) is preferable.

(However, A and B each independently represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—. A ′ and B ′ each represent Independently, a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, or —O—CO—CH Y ₁ is a group selected from a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and Each hydrogen atom bonded to may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. ₁ is a hydrogen atom —NO ₂ , —CN, —CH═C (CN) ₂ , — CH = CH—CN, a halogen group, an alkyl group, or an alkoxy group, and Z ₁ and Z ₂ each independently represent —CO—, —CH ₂ O—, —CH═N—, —CF ₂ —. R ₂ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. L represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 and m2 each independently represents an integer of 1 to 3. In the formulas (5) to (13), One or more of them may be substituted with the same or different ring selected from naphthalene ring, anthracene ring and fluorene ring.

[Liquid crystalline side chain polymer]
The side chain type polymer that is a component of the photosensitive composition used in the present invention can be obtained by the polymerization reaction of the photosensitive side chain monomer that exhibits the liquid crystal properties described above. Moreover, it can obtain by copolymerization of the photosensitive side chain monomer and liquid crystalline side chain monomer which do not express liquid crystallinity, and the copolymerization of the photosensitive side chain monomer and liquid crystalline side chain monomer which express liquid crystallinity. Moreover, it can copolymerize with another monomer in the range which does not impair liquid crystallinity expression ability.

Examples of other monomers include industrially available monomers capable of radical polymerization reaction. Specific examples of the other monomer include unsaturated carboxylic acid, acrylic ester compound, methacrylic ester compound, maleimide compound, acrylonitrile, maleic anhydride, styrene compound, vinyl compound and the like.

Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and the like.

Examples of the acrylic ester compound include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthryl methyl acrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl. Acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2- Propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, - ethyl-8 tricyclodecylacrylate the like.

Examples of the methacrylic acid ester compound include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthryl methyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl. Methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2- Propyl-2-adamantyl methacrylate, 8-me Le -8- tricyclodecyl methacrylate, 8-ethyl-8-tricyclodecyl methacrylate. (Meth) acrylate compounds having a cyclic ether group such as glycidyl (meth) acrylate, (3-methyl-3-oxetanyl) methyl (meth) acrylate, (3-ethyl-3-oxetanyl) methyl (meth) acrylate, and the like are also used. Can do.

Examples of the vinyl compound include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, propyl vinyl ether and the like.
Examples of the styrene compound include styrene, methylstyrene, chlorostyrene, bromostyrene, and the like.
Examples of the maleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide and the like.

The method for producing the photosensitive side chain type polymer in the present invention is not particularly limited, and a general-purpose method handled industrially can be used. Specifically, it can be produced by cationic polymerization, radical polymerization, or anionic polymerization using a vinyl group of a liquid crystalline side chain monomer or a photosensitive side chain monomer. Among these, radical polymerization is particularly preferable from the viewpoint of ease of reaction control.

As a polymerization initiator for radical polymerization, a known compound such as a radical polymerization initiator or a reversible addition-cleavage chain transfer (RAFT) polymerization reagent can be used.
The radical thermal polymerization initiator is a compound that generates radicals by heating to a decomposition temperature or higher. Examples of such radical thermal polymerization initiators include ketone peroxides (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), diacyl peroxides (acetyl peroxide, benzoyl peroxide, etc.), hydroperoxides (peroxidation). Hydrogen, tert-butyl hydride peroxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxyketals (dibutyl peroxy cyclohexane) Etc.), alkyl peresters (peroxyneodecanoic acid-tert-butyl ester, peroxypivalic acid-tert-butyl ester, peroxy 2-ethylcyclohex Acid-tert-amyl ester, etc.), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), azo compounds (azobisisobutyronitrile, 2,2'-di (2-hydroxyethyl) And azobisisobutyronitrile). Such radical thermal polymerization initiators can be used singly or in combination of two or more.

The radical photopolymerization initiator is not particularly limited as long as it is a compound that initiates radical polymerization by light irradiation. Examples of such radical photopolymerization initiators include benzophenone, Michler's ketone, 4,4′-bis (diethylamino) benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy -2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, isopropyl benzoin ether, isobutyl benzoin ether, 2,2-diethoxyacetophenone, 2,2 -Dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2- N-di-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 4,4′-di (t-butylperoxycarbonyl) benzophenone 3,4,4′-tri (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2- (4′-methoxystyryl) -4,6-bis (trichloromethyl) -S-triazine, 2- (3 ', 4'-dimethoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2', 4'-dimethoxystyryl) -4,6-bis (Trichloromethyl) -s-triazine, 2- (2′-methoxystyryl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (4′-pentyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 4- [pN, N-di (ethoxycarbonylmethyl)]-2, 6-di (trichloromethyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (2′-chlorophenyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (4 ′ -Methoxyphenyl) -s-triazine, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzthiazole, 2-mercaptobenzothiazole, 3,3′-carbonylbis (7-diethylamino) Coumarin), 2- (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bi (2-chlorophenyl) -4,4 ′, 5,5′-tetrakis (4-ethoxycarbonylphenyl) -1,2′-biimidazole, 2,2′-bis (2,4-dichlorophenyl) -4, 4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′bis (2,4-dibromophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2 ′ -Biimidazole, 2,2'-bis (2,4,6-trichlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole, 3- (2-methyl-2 -Dimethylaminopropionyl) carbazole, 3,6-bis (2-methyl-2-morpholinopropionyl) -9-n-dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, bis (5-2,4-cyclopentadi -1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone 3,3 ′, 4,4′-tetra (t-hexylperoxycarbonyl) benzophenone, 3,3′-di (methoxycarbonyl) -4,4′-di (t-butylperoxycarbonyl) benzophenone, 3,4 '-Di (methoxycarbonyl) -4,3'-di (t-butylperoxycarbonyl) benzophenone, 4,4'-di (methoxycarbonyl) -3,3'-di (t-butylperoxycarbonyl) benzophenone, 2 -(3-methyl-3H-benzothiazol-2-ylidene) -1-naphthalen-2-yl-ethanone or 2- (3-methyl-1 3- benzothiazol -2 (3H) - ylidene) -1- (2-benzoyl) ethanone, and the like. These compounds may be used alone or in combination of two or more.

The radical polymerization method is not particularly limited, and an emulsion polymerization method, suspension polymerization method, dispersion polymerization method, precipitation polymerization method, bulk polymerization method, solution polymerization method and the like can be used.
The organic solvent used for the polymerization reaction of the photosensitive side chain polymer capable of exhibiting liquid crystallinity is not particularly limited as long as the generated polymer is soluble. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide , Γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl Carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethyl Glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene Glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n- Hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, Ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropion , 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy -N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like.
These organic solvents may be used alone or in combination. Furthermore, even if it is a solvent which does not dissolve the polymer | macromolecule to produce | generate, you may mix and use the above-mentioned organic solvent in the range which the polymer | macromolecule produced | generated does not precipitate.

In radical polymerization, oxygen in the organic solvent becomes a cause of inhibiting the polymerization reaction. Therefore, it is preferable to use an organic solvent that has been deaerated to the extent possible.
The polymerization temperature at the time of radical polymerization can be arbitrarily selected from 30 to 150 ° C., but is preferably in the range of 50 to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the monomer concentration is preferably 1 to 50, more preferably 5 to 30. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.

In the above-mentioned radical polymerization reaction, the molecular weight of the obtained polymer is decreased when the ratio of the radical polymerization initiator is large relative to the monomer, and the molecular weight of the obtained polymer is increased when the ratio is small, the ratio of the radical initiator is The content is preferably 0.1 to 10 mol% with respect to the monomer to be polymerized. Further, various monomer components, solvents, initiators and the like can be added during the polymerization.

[Recovery of polymer]
When recovering the produced polymer from the reaction solution of the photosensitive side chain polymer capable of exhibiting liquid crystallinity obtained by the above reaction, the reaction solution is put into a poor solvent, What is necessary is just to precipitate a coalescence. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer deposited in a poor solvent and precipitated can be recovered by filtration and then dried at normal temperature or under reduced pressure at room temperature or by heating. In addition, when the polymer collected by precipitation is redissolved in an organic solvent and reprecipitation and collection is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the poor solvent at this time include alcohols, ketones, hydrocarbons and the like, and it is preferable to use three or more kinds of poor solvents selected from these because purification efficiency is further improved.

The molecular weight of the photosensitive side chain polymer capable of expressing liquid crystal contained in the photosensitive composition used in the present invention is the strength of the resulting side chain polymer film, the workability during film formation, and In consideration of the uniformity of the film, the weight average molecular weight measured by GPC (Gel Permeation Chromatography) method is preferably 2,000 to 1,000,000, more preferably 5,000 to 100,000.

[Preparation of photosensitive composition]
The photosensitive composition used in the present invention comprises a photosensitive side chain polymer that can exhibit liquid crystallinity. And it is preferable to prepare as a coating liquid so that it may become suitable for formation of a liquid crystal aligning film. That is, the photosensitive composition used in the present invention is preferably prepared as a solution in which a resin component for forming a resin film is dissolved in an organic solvent. Here, a resin component is a resin component containing the photosensitive side chain type polymer which can express the said liquid crystallinity. In that case, the content of the resin component is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass in the photosensitive composition.

In the above photosensitive composition, the resin component may be a photosensitive side chain polymer that can all exhibit liquid crystallinity, but other than those as long as the liquid crystal expression ability and the photosensitive performance are not impaired. A polymer may be mixed. In that case, the content of the other polymer in the resin component is 0.5 to 80% by mass, preferably 1 to 50% by mass.
Examples of such other polymers include polymers that are made of poly (meth) acrylate, polyamic acid, polyimide, and the like and are not a photosensitive side chain polymer that can exhibit liquid crystallinity.

<Organic solvent>
The organic solvent used for the photosensitive composition used for this invention will not be specifically limited if it is an organic solvent in which a resin component is dissolved. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, Dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3 -Dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4 Methyl-2-pentanone, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl Ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, etc. Is mentioned. These may be used alone or in combination.

The photosensitive composition used in the present invention may contain components other than those described above. Examples thereof include solvents and compounds that improve the film thickness uniformity and surface smoothness when the photosensitive composition is applied, and compounds that improve the adhesion between the liquid crystal alignment film and the substrate.

The following are mentioned as a specific example of the solvent (poor solvent) which improves the uniformity of film thickness and surface smoothness.
For example, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoacetate Isopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipro Lenglycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3 -Methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl Ether, 1-hexanol, n-hexane, n-pentane, n-octane Diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, Ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1 -Butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol- 1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactyl isoamyl ester, etc. Examples include solvents having surface tension.

These poor solvents may be used alone or in combination. When the above-described solvent is used, it is preferably 5 to 80% by mass, more preferably 20%, so that the solubility of the entire solvent contained in the photosensitive composition is not significantly reduced. ~ 60% by mass.

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
More specifically, for example, F-Top 301, EF303, EF352 (manufactured by Tochem Products), MegaFuck F171, F173, R-30 (manufactured by DIC), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard AG710 (Asahi Glass Co., Ltd.), Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC10 (AGC Seimi Chemical Co., Ltd.) and the like. The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the resin component contained in the photosensitive composition. .

Specific examples of the compound that improves the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds.
For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Examples thereof include propyltrimethoxysilane and N-bis (oxyethylene) -3-aminopropyltriethoxysilane.

Furthermore, in addition to improving the adhesion between the substrate and the liquid crystal alignment film, the addition of the following phenoplasts and epoxy group-containing compounds for the purpose of preventing the deterioration of electrical characteristics due to the backlight when the liquid crystal display element is constructed An agent may be contained in the photosensitive composition. Specific phenoplast additives are shown below, but are not limited to this structure.

Specific epoxy group-containing compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N ′,-tetraglycidyl-4, 4 ′ Such as diaminodiphenylmethane and the like.
When using a compound that improves the adhesion to the substrate, the amount used is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the resin component contained in the photosensitive composition. The amount is preferably 1 to 20 parts by mass. If the amount used is less than 0.1 parts by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the orientation of the liquid crystal may deteriorate.

A photosensitizer can also be added to the photosensitive composition used in the present invention. As the photosensitizer, a colorless sensitizer and a triplet sensitizer are preferable.
Specific examples of photosensitizers include aromatic nitro compounds, coumarins (7-diethylamino-4-methylcoumarin, 7-hydroxy4-methylcoumarin), ketocoumarins, carbonyl biscoumarins, aromatic 2-hydroxyketones, and amino acids. Substituted aromatic 2-hydroxy ketones (2-hydroxybenzophenone, mono- or di-p- (dimethylamino) -2-hydroxybenzophenone), acetophenone, anthraquinone, xanthone, thioxanthone, benzanthrone, thiazoline (2-benzoyl) Methylene-3-methyl-β-naphthothiazoline, 2- (β-naphthoylmethylene) -3-methylbenzothiazoline, 2- (α-naphthoylmethylene) -3-methylbenzothiazoline, 2- (4-biphenoyl) Methylene) -3-methylben Thiazoline, 2- (β-naphthoylmethylene) -3-methyl-β-naphthothiazoline, 2- (4-biphenoylmethylene) -3-methyl-β-naphthothiazoline, 2- (p-fluorobenzoylmethylene)- 3-methyl-β-naphthothiazoline), oxazoline (2-benzoylmethylene-3-methyl-β-naphthoxazoline, 2- (β-naphthoylmethylene) -3-methylbenzoxazoline, 2- (α-naphthoylmethylene) ) -3-methylbenzoxazoline, 2- (4-biphenoylmethylene) -3-methylbenzoxazoline, 2- (β-naphthoylmethylene) -3-methyl-β-naphthoxazoline, 2- (4-biphenoyl) Methylene) -3-methyl-β-naphthoxazoline, 2- (p-fluorobenzoylmethylene) -3-methyl -Β-naphthoxazoline), benzothiazole, nitroaniline (m- or p-nitroaniline, 2,4,6-trinitroaniline) or nitroacenaphthene (5-nitroacenaphthene), (2-[(m- Hydroxy-p-methoxy) styryl] benzothiazole, benzoin alkyl ether, N-alkylated phthalone, acetophenone ketal (2,2-dimethoxyphenylethanone), naphthalene, anthracene (2-naphthalenemethanol, 2-naphthalenecarboxylic acid, 9 -Anthracene methanol, 9-anthracenecarboxylic acid), benzopyran, azoindolizine, melocoumarin and the like.
Aromatic 2-hydroxyketone (benzophenone), coumarin, ketocoumarin, carbonyl biscoumarin, acetophenone, anthraquinone, xanthone, thioxanthone, or acetophenone ketal is preferable.

In the photosensitive composition, in addition to those described above, a dielectric, a conductive substance, or the like for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, as long as the effects of the present invention are not impaired. Furthermore, a crosslinkable compound may be added for the purpose of increasing the hardness and density of the liquid crystal alignment film.

[Liquid crystal alignment film and liquid crystal display element]
The photosensitive composition used in the present invention, after being applied on a substrate and subjected to photo-alignment treatment by light irradiation, imparts alignment control ability with high efficiency by heating to a temperature at which the liquid crystal alignment film exhibits liquid crystallinity, Furthermore, the alignment state obtained by heating can be fixed by irradiating ultraviolet rays. In this way, the photosensitive composition can form a liquid crystal alignment film through a photo-alignment treatment, a heating step up to the liquid crystal phase transition temperature, and irradiation with non-polarized ultraviolet rays. Can be used.
The liquid crystal display element is obtained by obtaining a substrate with a liquid crystal alignment film from the photosensitive composition used in the present invention, and then preparing a liquid crystal cell by a known method to obtain a lateral electric field drive type liquid crystal display element.

To give an example of the production of a liquid crystal cell, prepare a pair of substrates on which a liquid crystal alignment film is formed, spread spacers on the liquid crystal alignment film of one substrate, and make the liquid crystal alignment film surface inside. A method of laminating the other substrate and injecting liquid crystal under reduced pressure, or a method of laminating liquid crystal on the liquid crystal alignment film surface on which spacers are dispersed, and then laminating the substrate and sealing, etc. It can be illustrated. At this time, it is preferable to use a substrate having an electrode having a structure like a comb for driving a horizontal electric field as the substrate on one side. The diameter of the spacer at this time is preferably 1 μm to 30 μm, more preferably 2 μm to 10 μm. This spacer diameter determines the distance between the pair of substrates that sandwich the liquid crystal layer, that is, the thickness of the liquid crystal layer.

The embodiment of the present invention will be described in more detail with reference to examples. In addition, this invention is limited to these and is not interpreted.
Abbreviations used in the examples are as follows.

(Methacrylic monomer)

(Organic solvent)
THF: Tetrahydrofuran NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (polymerization initiator)
AIBN: 2,2′-azobisisobutyronitrile

[Measurement of phase transition temperature]
The liquid crystal phase transition temperature of the polymer obtained in the example was measured using differential scanning calorimetry (DSC) and DSC3100SR (manufactured by Mac Science).

<Synthesis Example 1>
MA1 (2.33 g, 7.0 mmol) was dissolved in NMP (21.5 g), degassed with a diaphragm pump, then AIBN (57.5 mg, 0.35 mmol) was added and degassed again. It was. Thereafter, the mixture was reacted at 65 ° C. for 20 hours to obtain a polymer solution of methacrylate. BC (15.9 g) was added to this polymer solution and stirred to obtain a liquid crystal aligning agent (A) as a photosensitive composition. The number average molecular weight of the polymer in this liquid crystal aligning agent (A) was 16000, and the weight average molecular weight was 28000. The liquid crystal phase transition temperature of this polymer was 145 to 190 ° C.

<Synthesis Example 2>
After MA1 (0.47 g, 1.4 mmol) and MA2 (1.72 g, 5.6 mmol) were dissolved in NMP (20.2 g) and deaerated with a diaphragm pump, AIBN (57.5 mg, 0.35 mmol) was added and deaeration was performed again. Thereafter, the mixture was reacted at 65 ° C. for 20 hours to obtain a polymer solution of methacrylate. BC (14.9g) was added and stirred to this polymer solution, and the liquid crystal aligning agent (B) which is a photosensitive composition was obtained. The number average molecular weight of the polymer in this liquid crystal aligning agent was 14000, and the weight average molecular weight was 24000. The liquid crystal phase transition temperature of this polymer was 135 to 180 ° C.

<Example 1>
[Production of liquid crystal cell]
Using the liquid crystal aligning agent (A) obtained in Synthesis Example 1, a liquid crystal cell was prepared according to the procedure shown below. The substrate used was a glass substrate having a size of 30 mm × 40 mm and a thickness of 0.7 mm, on which comb-like pixel electrodes formed by patterning an ITO film were arranged. The pixel electrode has a comb-like shape configured by arranging a plurality of “<”-shaped electrode elements having a bent central portion. The width in the short direction of each electrode element is 10 μm, and the distance between the electrode elements is 20 μm. The pixel electrode forming each pixel is formed by arranging a plurality of bent “<”-shaped electrode elements at the center, so that the shape of each pixel is not rectangular but is the same as the electrode element. It has a shape that resembles the bold “<” character that bends at the part. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side. When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the alignment processing direction of the liquid crystal alignment film described later is used as a reference, the electrode element of the pixel electrode is formed to form an angle of + 15 ° (clockwise) in the first region of the pixel, and in the second region of the pixel. The electrode elements of the pixel electrode are formed so as to form an angle of −15 ° (clockwise). That is, in the first region and the second region of each pixel, the directions of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode are mutually in the substrate plane. It is comprised so that it may become a reverse direction.

The liquid crystal aligning agent (A) obtained in Example 1 was spin-coated on the prepared substrate with electrodes. Subsequently, it dried for 90 second with a 70 degreeC hotplate, and formed the photosensitive side chain type polymer film with a film thickness of 100 nm. Next, the film surface was irradiated with 5 mJ / cm ² of 313 nm ultraviolet light through a polarizing plate and heated on a hot plate at 150 ° C. for 10 minutes to obtain a substrate with a liquid crystal alignment film made of a side chain polymer film. In addition, a photosensitive side chain polymer film was similarly formed on a glass substrate having a columnar spacer having a height of 4 μm on which an electrode was not formed as a counter substrate, and an orientation treatment was performed. A sealant (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was printed on the liquid crystal alignment film of one substrate. Next, the other substrate was bonded so that the liquid crystal alignment film surfaces of both substrates faced each other and the alignment direction was 0 °, and then the sealing agent was thermally cured to produce an empty cell. A liquid crystal cell having a configuration of an IPS (In-Planes Switching) mode liquid crystal display element is prepared by injecting liquid crystal, MLC-2041 (manufactured by Merck) into the empty cell by a reduced pressure injection method, sealing the injection port. Obtained.

(Secondary irradiation process)
After producing the liquid crystal cell, a realignment treatment was performed in an oven at 120 ° C. for 60 minutes. Thereafter, in a state where the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, the liquid crystal cell was irradiated with ultraviolet rays through a 365 nm band-pass filter at 20 J / cm ² (secondary irradiation). After the secondary irradiation, the voltage holding ratio of the liquid crystal cell was measured. Further, afterimage evaluation and cell observation after aging were performed. The liquid crystal cell was aged in a 60 ° C. oven for 336 hours. The liquid crystal cell after aging was observed for the occurrence of bright spots or alignment defects.

(Measurement of voltage holding ratio)
The voltage holding ratio of the liquid crystal cell was measured by applying a voltage of 5 V for 60 μs at a temperature of 70 ° C., and calculating how much the voltage could be held after 1667 ms as the voltage holding ratio. For measurement of the voltage holding ratio, VHR-1 manufactured by Toyo Corporation was used.

(Afterimage evaluation)
The IPS mode liquid crystal cell prepared in Example 1 is installed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the backlight is turned on in the state where no voltage is applied. The arrangement angle of the liquid crystal cell was adjusted so as to be the smallest. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the pixel was darkest to the angle at which the first region was darkest was calculated as the initial orientation azimuth. Next, an alternating voltage of 16 V _PP was applied at a frequency of 30 Hz in an oven at 60 ° C. for 336 hours. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for 1 hour. After standing, the orientation azimuth was measured in the same manner, and the difference in orientation azimuth before and after AC driving was calculated as an angle Δ (deg.).

(Cell observation after aging)
The liquid crystal cell after the afterimage evaluation was observed through a polarizing microscope with the polarizing plate in a crossed Nicol state. When the liquid crystal cell was rotated to be in a black display state, a state in which there was no bright spot or poor alignment was considered good.

<Example 2>
In the secondary irradiation process, a cell was produced in the same procedure as in Example 1 except that ultraviolet rays that passed through a 313 nm bandpass filter were irradiated with 5 J / cm ² (secondary irradiation). The evaluation results are shown in Table 1.

<Example 3>
In the same manner as in Example 1, the liquid crystal aligning agent (A) obtained in Synthesis Example 1 was spin-coated on a substrate with electrodes. Subsequently, it dried for 90 second with a 70 degreeC hotplate, and formed the liquid crystal aligning film with a film thickness of 100 nm. Next, the surface of the photosensitive side chain polymer film was irradiated with 5 mJ / cm ² of 313 nm ultraviolet light through a polarizing plate, heated on a hot plate at 150 ° C. for 10 minutes, the substrate was cooled for 30 minutes, and the side chain was further cooled. A substrate with a liquid crystal alignment film was obtained by irradiating ultraviolet rays through a 365 nm band-pass filter with 1 J / cm ² (secondary irradiation) on the surface of the mold polymer film. Moreover, it carried out similarly to Example 1, and obtained the liquid crystal cell provided with the structure of the IPS mode liquid crystal display element combining the opposing board | substrate. Thereafter, in the same manner as in Example 1, reorientation treatment was performed, voltage holding ratio measurement, afterimage evaluation, and cell observation after aging were performed.

<Example 4>
In the secondary irradiation process on the substrate, the same procedure as in Example 3 was used, except that the side chain polymer film surface was irradiated with 500 mJ / cm ^{2 of} ultraviolet light (secondary irradiation) through a 313 nm bandpass filter. A cell was produced. The evaluation results are shown in Table 1.

<Examples 5 to 8>
Using the liquid crystal aligning agent (B) obtained in Synthesis Example 2, a liquid crystal cell was produced in the same manner as in Examples 1 to 4. Table 1 summarizes the liquid crystal aligning agent used, the ultraviolet irradiation amount (primary irradiation), the secondary irradiation wavelength, the secondary irradiation amount, and the evaluation results.

<Comparative Example 1>
In Comparative Example 1, a liquid crystal cell was prepared in the same procedure as in Example 1, and then realignment treatment was performed in an oven at 120 ° C. for 60 minutes, but the secondary irradiation process was not performed. This liquid crystal cell was also subjected to voltage holding ratio measurement, afterimage evaluation, and cell observation after aging. The liquid crystal aligning agent used and the evaluation results are shown in Table 1.

<Comparative example 2>
In Comparative Example 2, a liquid crystal cell was prepared in the same procedure as in Example 5, and then re-aligned in an oven at 120 ° C. for 60 minutes, but the secondary irradiation process was not performed. This liquid crystal cell was also subjected to voltage holding ratio measurement, afterimage evaluation, and cell observation after aging. The liquid crystal aligning agent used and the evaluation results are shown in Table 1.

From the above results, the liquid crystal cell in which the secondary irradiation process was introduced showed a higher voltage holding ratio than the cell not subjected to the secondary irradiation. This is presumably because unreacted photosensitive groups were reduced and cross-linking proceeded between the polymers by the photodimerization reaction.

Furthermore, as a result of observing the cells after aging, the cells subjected to the secondary irradiation showed good orientation, but in Comparative Examples 1 and 2 where the secondary irradiation was not performed, minute bright spots were generated. . This is presumably because the remaining unreacted photosensitive groups and monomers move or crystallize due to thermal aging, thereby inhibiting the alignment of the liquid crystal. However, it is considered that the generation of bright spots was suppressed by the consumption of residual unreacted groups and monomers by introducing the secondary irradiation process.

Industrial applicability

According to the present invention, it is possible to obtain a liquid crystal display element excellent in reliability while maintaining a high-efficiency alignment control capability. This horizontal electric field drive type liquid crystal display element is a large-screen high-definition liquid crystal television. It can utilize suitably for various display uses, such as.
It should be noted that the entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2013-57047 filed on March 19, 2013 is cited here as the disclosure of the specification of the present invention. Incorporated.

1: side chain polymer membrane, 2, 2a: side chain 3: side chain polymer membrane, 4, 4a: side chain 5: side chain polymer membrane, 6, 6a: side chain 7: side chain type Polymer membrane 8, 8a: Side chain

Claims (15)

1. Step [I]: (A) a photosensitive side chain polymer that exhibits liquid crystallinity in a certain temperature range of 100 ° C. to 250 ° C. on a substrate having a conductive film for driving a lateral electric field, and (B) an organic Applying a photosensitive composition containing a solvent to form a photosensitive side chain polymer film;
   Step [II]: a step of irradiating the photosensitive side chain polymer film with polarized ultraviolet rays to form a side chain polymer film,
   Step [III]: a step of heating the side chain polymer film,
   Step [IV]:] Further, a step of irradiating the side chain polymer film with ultraviolet rays,
   In the order, a method of manufacturing a lateral electric field drive type liquid crystal display element.
2. The amount of UV irradiation in step [II] maximizes ΔA, which is the difference between the UV absorbance in the direction parallel to the polarization direction of the polarized UV light and the UV absorbance in the direction perpendicular to the polarization direction of the polarized UV light. The production method according to claim 1, wherein the amount falls within a range of 1% to 70% of the amount of ultraviolet irradiation.
3. 3. The production method according to claim 1, wherein the ultraviolet irradiation amount in the step [II] is within a range of 1% to 50% of the ultraviolet irradiation amount that maximizes the ΔA.
4. The heating temperature in step [III] is a temperature in a range from a temperature 10 ° C. lower than the lower limit of the temperature range in which the side chain polymer film exhibits liquid crystallinity to a temperature 10 ° C. lower than the upper limit of the temperature range. Item 4. The production method according to any one of Items 1 to 3.
5. The photosensitive group contained in the photosensitive side chain polymer exhibiting liquid crystallinity is azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan, phenylbenzoate, or a derivative thereof. 5. The production method according to any one of 1 to 4.
6. The production method according to any one of claims 1 to 5, wherein an ultraviolet irradiation amount in the step [IV] is an irradiation amount with which 20 mol or more reacts with respect to 100 mol of the photosensitive group of the side chain polymer film. .
7. The manufacturing method according to any one of claims 1 to 6, wherein step [IV] is performed after the production of the liquid crystal display element.
8. The production method according to any one of claims 1 to 7, wherein the component (A) has a side chain that undergoes photocrosslinking, photoisomerization, or photofleece transition.
9. The component (A) has a photosensitive side chain polymer having at least one photosensitive side chain selected from the group consisting of the following formulas (1) to (13). The production method according to item.
   

   

   

   However, A, B, and D each independently represent a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. A ′ and B ′ are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, Or, —O—CO—CH═CH— is represented. Y ₁ is a group selected from a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and the hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl or alkoxy group having 1 to 4 carbon atoms. X represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, or —C≡C—.
   X ′ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, —CH═CH—CO—O—, or —O—CO—CH. ═CH—, and when the number of X ′ is 2, X ′ may be the same or different. l represents an integer of 1 to 12, m represents an integer of 0 to 2, m1, m2, and m3 each independently represents an integer of 1 to 3, and n represents an integer of 0 to 12 (where n = 0 In this case, B represents a single bond). Y ₂ is a group selected from a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and the hydrogen atom bonded to them is Each may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl or alkoxy group having 1 to 12 carbon atoms. R represents —OH, —NH ₂ , an alkoxy group having 1 to 6 carbon atoms or an alkylamino group having 1 to 6 carbon atoms. R ₁ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl or alkoxy group having 1 to 12 carbon atoms. One or more of the benzene rings in the formulas (1) to (8) may be substituted with the same or different rings selected from a naphthalene ring, an anthracene ring and a fluorene ring.
10. The component (A) has a liquid crystalline side chain polymer having at least one liquid crystalline side chain selected from the group consisting of the following formulas (5) to (8) and (14) to (22). Item 10. The production method according to any one of Items 1 to 9.
    

    

    

    (However, A and B each independently represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. A ′ and B ′ represent Each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, or —O—CO—. CH = CH— Y ₁ is a group selected from a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, The hydrogen atoms bonded thereto may be each independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. R ₁ is a hydrogen atom —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, or an alkyl group or alkoxy group having 1 to 12 carbon atoms, Z ₁ and Z ₂ are each independently —CO—, —CH ₂ O—, —CH═N—. , -CF ₂ - .R ₂ representing a hydrogen _{atom, -NO 2, -CN, -CH =} C (CN) 2, alkyl groups of -CH = CH-CN, halogen group, or a C 1-12 or Represents an alkoxy group, l represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1, m2, and m3 each independently represents an integer of 1 to 3. Formulas (5) to (8) And one or more of the benzene rings in (14) to (22) may be substituted with the same or different rings selected from a naphthalene ring, an anthracene ring and a fluorene ring.
11. (A) a photosensitive side-chain polymer that exhibits liquid crystallinity in a temperature range of 100 ° C. to 250 ° C., and (B) a photosensitive composition containing an organic solvent,
    [I] A step of coating the photosensitive composition on a substrate having a conductive film for driving a lateral electric field to form a photosensitive side chain polymer film, [II] The photosensitive side chain polymer film A step of irradiating the side chain type polymer film by irradiating with polarized ultraviolet rays, [III] a step of heating the side chain type polymer film, and [IV] a step of irradiating the side chain type polymer film with ultraviolet rays. Is a photosensitive composition used in a method for producing a horizontal electric field drive type liquid crystal display device having the above-mentioned order.
12. The photosensitive composition according to claim 11, wherein the component (A) has a side chain that undergoes photocrosslinking, photoisomerization, or photofleece transition.
13. The photosensitive composition according to claim 11 or 12, wherein the component (A) has at least one photosensitive side chain selected from the group consisting of the following formulas (1) to (13).
    

    

    

    (However, A, B and D each independently represent a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, and Y ₁ represents a monovalent group. A benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, and a combination thereof, and each hydrogen atom bonded thereto is independently —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group, where X is a single bond, —COO—, —OCO— , -N = N-, -CH = CH-, -C≡C-, l represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 and m2 each independently represents 1 to Represents an integer of 3, n is an integer of 0 to 12 (provided that when n = 0, B is a single bond) Y ₂ is a group selected from a divalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and Each hydrogen atom bonded to may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. Represents OH, NH ₂ , an alkoxy group having 1 to 6 carbon atoms or an alkylamino group having 1 to 6 carbon atoms, wherein R ₁ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , — CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group The same or phase in which one or more of the benzene rings in formulas (1) to (8) are selected from a naphthalene ring, an anthracene ring, and a fluorene ring Become ring may be substituted.)
14. The photosensitive composition according to claim 11 or 12, wherein the component (A) has at least one liquid crystalline side chain selected from the group consisting of the following formulas (5) to (8) and (14) to (22). object.
    

    

    

    

    (However, A and B each independently represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—. A ′ and B ′ each represent Independently, a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, —NH—CO—, —CH═CH—CO—O—, or —O—CO—CH Y ₁ is a group selected from a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, cyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and Each hydrogen atom bonded to may be independently substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkoxy group. ₁ is a hydrogen atom —NO ₂ , —CN, —CH═C (CN) ₂ , — CH = CH—CN, a halogen group, an alkyl group, or an alkoxy group, and Z ₁ and Z ₂ each independently represent —CO—, —CH ₂ O—, —CH═N—, —CF ₂ —. R ₂ represents a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. L represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 and m2 each independently represents an integer of 1 to 3. Formulas (5) to (8) and (14) (One or more of the benzene rings in (22) may be substituted with the same or different rings selected from a naphthalene ring, an anthracene ring, and a fluorene ring.)
15. A liquid crystal display device manufactured by the method for manufacturing a liquid crystal display device according to any one of claims 1 to 10.

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