WO2014017497A1

WO2014017497A1 - Method for manufacturing liquid crystal alignment film, liquid crystal alignment film, liquid crystal display element, polymer, and liquid crystal aligning agent

Info

Publication number: WO2014017497A1
Application number: PCT/JP2013/069939
Authority: WO
Inventors: 耕平後藤; 隆之根木; 喜弘川月; 瑞穂近藤
Original assignee: 日産化学工業株式会社
Priority date: 2012-07-24
Filing date: 2013-07-23
Publication date: 2014-01-30
Also published as: JP2017214587A; CN107200818A; JPWO2014017497A1; TWI597296B; JP6586438B2; TW201722998A; CN107200818B; KR102058769B1; JP6268089B2; TWI617585B; CN104937480B; TW201418289A; KR20150038108A; CN104937480A

Abstract

Provided are a method for manufacturing a liquid crystal alignment film having high light utilization efficiency, a liquid crystal alignment film, and a liquid crystal display element. The liquid crystal aligning agent of the present invention is prepared by polymerizing polysiloxane and a monomer having liquid crystal properties, a photosensitive group, and a radical polymerizable group to obtain a polymer. After a side-chain-type polymer film (1) is obtained from the liquid crystal aligning agent, an aligning process is performed by irradiating polarized ultraviolet rays, then the product is heated, and side chains (2) of the side-chain-type polymer film (1) are realigned. A liquid crystal alignment film is then fabricated by heating the product at a higher temperature to fix the realigned state. The temperature of heating for realignment is 200°C or lower, for example, or another temperature ranging from 10°C higher than the lower limit of the temperature range at which the side-chain-type polymer film (1) exhibits liquid crystal properties to 10°C lower than the upper limit of this temperature range. A liquid crystal display element is manufactured using the resultant liquid crystal alignment film.

Description

Method for producing liquid crystal alignment film, liquid crystal alignment film, liquid crystal display element, polymer, and liquid crystal alignment agent

The present invention relates to a polymer and a liquid crystal aligning agent suitable for a method for producing a highly efficient liquid crystal aligning film using light, and a liquid crystal aligning film and a liquid crystal display element.

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 such a 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 constituent member of the liquid crystal display element, and is formed on a 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 and relatively realize a liquid crystal alignment state, it has been used in the manufacturing process of a conventional liquid crystal display element. 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 in which the surface of the liquid crystal alignment film made of polyimide or the like is rubbed, generation of dust or 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 could not 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. 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, the polyimide film is irradiated with polarized ultraviolet light, and anisotropic decomposition is caused by utilizing the polarization direction dependence of the ultraviolet absorption of the molecular structure. Then, the liquid crystal is aligned by the polyimide remaining without being decomposed (see, for example, 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 orthogonal 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 (see Non-Patent Document 2, for example).

In recent years, in the photo-alignment method, a technique for improving the alignment control ability of the liquid crystal alignment film by combining a light irradiation treatment and a heating process has been studied (see, for example, Patent Documents 2 to 4).

As in the above example, the alignment treatment method of the liquid crystal alignment film by the photo-alignment method uses a reaction by light such as a photocrosslinking reaction or a photoisomerization reaction. Therefore, the material used for forming the liquid crystal alignment film is required to have photoreactivity that enables it. For example, in Non-Patent Document 1 described above, polyvinyl cinnamate is used as the material of the liquid crystal alignment film.

On the other hand, the liquid crystal alignment film is required to have excellent reliability as described above. Therefore, as described above, a polyimide organic film having excellent reliability such as heat resistance and electrical characteristics has been used for the liquid crystal alignment film by the conventional rubbing treatment. Therefore, the liquid crystal alignment film by the photo-alignment method is required to satisfy both photoreactivity and reliability.
Recently, in the field of polymer materials, for example, a technique for obtaining a highly reliable polymer material such as an acrylic-siloxane hybrid material in which an acrylic polymer and a siloxane polymer are separately polymerized and mixed is known ( For example, see Patent Documents 5 to 9).
However, in the field of liquid crystal alignment films by the photo-alignment method, which must be applied to photoreactions, the introduction of such highly reliable hybrid materials has not progressed.

Japan No. 3893659 Specification Japanese Unexamined Patent Publication No. 2007-304215 Japanese Unexamined Patent Publication No. 2007-232934 Japanese Unexamined Patent Publication No. 2008-276149 Japanese Unexamined Patent Publication No. 7-243173 Japanese Unexamined Patent Publication No. 9-208642 Japanese Laid-Open Patent Publication No. 4-261454 Japanese Unexamined Patent Publication No. 2003-313233 Japanese Unexamined Patent Publication No. 1-168971

As described above, the photo-alignment method eliminates the rubbing process itself and has a great advantage as compared with the rubbing method that has been industrially used as an alignment treatment method for liquid crystal display elements. For example, an alignment process can be performed 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. In addition, compared to the rubbing method in which the alignment control ability is almost constant by rubbing, the alignment control ability can be controlled by changing the irradiation amount of polarized light in the photo-alignment method.

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 is required, which is low efficiency and stable liquid crystal alignment is realized. There were cases where it was not possible.

For example, in the decomposition type photo-alignment method described in Patent Document 1 described above, 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. It becomes. Further, even in the case of dimerization type or photoisomerization type photo-alignment methods, 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.

As described above, a technique for improving the alignment control ability of the liquid crystal alignment film by combining the heating process with the light irradiation treatment has been studied, but there is a problem with the heat resistance of the material or when the heat resistance is sufficient There are problems such as extremely poor solvent solubility.
In addition, regarding the compatibility between photoreactivity and reliability, a sufficient material for photo-alignment method has not been developed yet.

Therefore, in the photo-alignment method, there is a demand for higher efficiency of alignment treatment and realization of stable liquid crystal alignment, and development of a method for producing a liquid crystal alignment film that can impart excellent alignment control ability to the liquid crystal alignment film with high efficiency. Is required. And it is preferable that the manufacturing method of the liquid crystal aligning film is implement | achieved using a highly reliable polymer.

An object of the present invention is to provide a highly efficient liquid crystal alignment film manufacturing method using light, to provide a liquid crystal alignment film, and to provide a liquid crystal display element having the obtained liquid crystal alignment film.

Another object of the present invention is to provide a polymer suitable for a method for producing a highly efficient liquid crystal alignment film using light, and a liquid crystal aligning agent containing the polymer.

That is, the present invention has the following gist.
(1) Step [I] of forming a photosensitive side chain polymer film that exhibits liquid crystallinity in a predetermined temperature range on a substrate;
Irradiating the side chain type polymer film with polarized ultraviolet rays [II],
The step [III] of heating the side chain polymer film irradiated with ultraviolet rays at a temperature within a range where the side chain polymer film exhibits liquid crystallinity, and the heated side chain polymer film Step [IV] for further heating at a temperature equal to or higher than the heating temperature in Step [III]
A method for producing a liquid crystal alignment film, comprising:

(2) The heating temperature in step [III] ranges from a temperature 10 ° C. higher 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 liquid crystal temperature range. The manufacturing method of the liquid crystal aligning film as described in said (1) which is inside.
(3) The method for producing a liquid crystal alignment film according to (1) or (2), wherein the heating temperature in the step [III] is a temperature of 200 ° C. or lower.

(4) The method for producing a liquid crystal alignment film according to any one of the above (1) to (3), wherein the heating temperature in the step [III] is a temperature at which the side chain of the side chain polymer film is realigned .
(5) The heating temperature in the step [III] is a temperature at which the side chain of the side chain polymer film is reoriented, and the heating temperature in the step [IV] fixes the reorientation in the step [III]. The method for producing a liquid crystal alignment film according to any one of the above (1) to (4), which is a temperature.

(6) The group in which the photosensitive group contained in the photosensitive side chain polymer film exhibiting liquid crystallinity is composed of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. 6. The method for producing a liquid crystal alignment film according to any one of (1) to (5), wherein the liquid crystal alignment film is a group derived from at least one selected from the group consisting of:

(7) The side chain polymer film is composed of at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, acrylate, methacrylate, maleimide, α-methylene-γ-butyrolactone and siloxane. (1) comprising a structure having a main chain and at least one side chain selected from the group consisting of the following formulas (1) to (5), formula (7), and formula (8): A method for producing a liquid crystal alignment film according to any one of (6) to (6).

(In Formula (1), A ₁ and B ₁ each independently represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. Y ₁ represents a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, Independently, it may be substituted with —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group, wherein X ₁ is a single bond, — COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —, wherein l1 represents an integer of 1 to 12 and m1 represents 1 to 3 Represents an integer, and n1 represents an integer of 1 to 12.

In the formula (2), A ₂ , B ₂ , and D ₁ are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO. -Represents. Y ₂ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded thereto are each independently , —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. X ₂ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —. R ₁ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l2 represents an integer of 1 to 12, m2 represents an integer of 1 to 3, and n2 represents an integer of 1 to 12.

In Formula (3), A ₃ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. X ₃ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —. R ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l3 represents an integer of 1 to 12, and m3 represents an integer of 1 to 3.
In the formula (4), l4 represents an integer of 1 to 12.

In Formula (5), A ₄ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. X ₄ represents —COO—. Y ₃ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, or a combination thereof, and a hydrogen atom bonded thereto is independently —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. l5 represents an integer of 1 to 12, and m4 represents an integer of 1 to 3.

In formula (7), A ₅ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. R ₃ is a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group having 1 to 6 carbon atoms, or an alkyloxy group having 1 to 6 carbon atoms. Or a group consisting of a combination thereof. l6 represents an integer of 1 to 12. The hydrogen atom bonded to the benzene ring in formula (7) is independently —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyl group. It may be substituted with an oxy group.

In Formula (8), A ₆ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. B ₃ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —. W ₁ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or 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 alkyloxy group. l7 represents an integer of 1 to 12, and m ₅ and m ₆ each independently represents an integer of 1 to 3. )

(8) The side chain type polymer film comprises a polysiloxane (a) having a radical polymerizable group and a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group. The method for producing a liquid crystal alignment film according to any one of the above (1) to (7), comprising a polymer obtained by radical polymerization.

(9) The liquid crystalline and photosensitive group of the monomer (b) is at least one selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. The manufacturing method of the liquid crystal aligning film as described in said (8) which is group derived | led-out from.

(10) A liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film according to any one of (1) to (9).
(11) A liquid crystal display device having the liquid crystal alignment film according to (10).

(12) A polymer obtained by radical polymerization of a polysiloxane (a) having a radical polymerizable group and a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group.

(13) The polymer according to claim 12, wherein the polysiloxane (a) is a polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane of the following formula (10).
R ¹³ _s1 Si (OR ¹⁴ ) _s2 (10)
(In Formula (10), R ¹³ represents an alkyl group substituted with an acryl group, a methacryl group, a styryl group, or an aryl group. R ¹⁴ represents hydrogen or an alkyl group having 1 to 5 carbon atoms. S1 Is 1 or 2, and S2 is 2 or 3.)
(14) The liquid crystalline and photosensitive group of the monomer (b) is at least one selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. The polymer according to (12) or (13) above, which is a group derived from

(15) The monomer (b) includes a polymerizable group composed of at least one selected from the group consisting of hydrocarbons, acrylates, methacrylates, maleimides and α-methylene-γ-butyrolactone, and the following formula (1): Any one of the above (12) to (14), which is a monomer having at least one side chain selected from the group consisting of formula (5), formula (7), and formula (8) The polymer described.

(16) Any one of (12) to (15) above, wherein the amount of the monomer (b) used is 0.5 to 50 mol with respect to 1 mol of alkoxysilane when the polysiloxane (a) is obtained. Item 1. The polymer according to item 1.
(17) A liquid crystal aligning agent containing the polymer according to any one of (12) to (16).

In addition, the side chain type polymer film of the present invention may be used in combination with a side chain structure having no photoreactivity as long as liquid crystallinity and photoreactivity are not lost.
An example of a side chain structure that does not have photoreactivity includes a structure represented by the following formula (6).

In the above formula (6), E ₁ represents a single bond, —O—, —CH ₂ —, —COO, —OCO—, —CONH—, or —NH—CO—.
Z represents a single bond, —COO, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —.
k1 represents an integer of 1 to 12, and p1 and q1 each independently represents an integer of 0 to 3.
R ₄ is a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyloxy group having 1 to 6 carbon atoms, a carboxyl group, or a combination thereof. Represents a group.

According to the present invention, a liquid crystal alignment film can be obtained by realizing a highly efficient alignment process using light by a method for producing a liquid crystal alignment film that enables a highly efficient alignment process. A liquid crystal display element is obtained.
Furthermore, according to this invention, the polymer which can be used suitably for the above liquid crystal aligning films, and the liquid crystal aligning agent containing this polymer are obtained.

It is a figure which illustrates typically the anisotropic introduction process in the manufacturing method of the liquid crystal aligning film of the 1st form of this invention, (a) is a figure which shows the state of the side chain type polymer film before polarized light irradiation (B) is a view showing the state of the side chain polymer film after irradiation with polarized light, (c) is a view showing the state of the side chain polymer film after heating, and (d ) Is a diagram showing a state of the side chain polymer film in which the orientation is fixed by performing a second heat treatment after heating.

It is a figure which illustrates typically the anisotropic introduction process in the manufacturing method of the liquid crystal aligning film of the 2nd form of this invention, (a) is a figure which shows the state of the side chain type polymer film before polarized light irradiation (B) is a figure which shows the state of the side chain type polymer film after polarized light irradiation, (c) is a figure which shows the state of the side chain type polymer film after a heating.

It is an ultraviolet absorption spectrum of a liquid crystal aligning film obtained in Example 4 in parallel and perpendicular to the polarized electric field vector of the irradiated ultraviolet light. It is an ultraviolet absorption spectrum parallel and perpendicular | vertical with respect to the polarization | polarized-light electric field vector of the irradiated ultraviolet-ray of the liquid crystal aligning film obtained in Example 6. FIG.

As a result of intensive studies, the inventor has obtained the following knowledge and completed the present invention.
The method for producing a liquid crystal alignment film of the present invention uses a method in which an alignment treatment is performed by irradiation with polarized light without using a rubbing treatment, using a photosensitive side chain polymer film capable of exhibiting liquid crystallinity.
The photosensitive side chain polymer film capable of exhibiting liquid crystallinity includes a polysiloxane (a) having a radical polymerizable group, a monomer having a liquid crystalline and photosensitive group, and a radical polymerizable group ( b) and a polymer obtained by radical polymerization.

After the irradiation of polarized light, a step of heating the side chain polymer film is provided to produce a liquid crystal alignment film. At this time, a heating process is made into two steps, the 1st heating process and 2nd heating process from which temperature differs. Furthermore, by optimizing the irradiation amount of polarized light and the heating temperature in the first heating step after the polarized light irradiation, highly efficient alignment processing is realized in the liquid crystal alignment film. Thereafter, in the second heating step, the alignment state formed in the liquid crystal alignment film is fixed. As a result, in the present invention, it is possible to achieve high alignment and good alignment control ability in the liquid crystal alignment film.
The present invention will be described in detail below.

<Side chain polymer (polymer) and side chain polymer film>
The photosensitive side chain polymer film that can exhibit liquid crystallinity used in the method for producing a liquid crystal alignment film of the present invention is a photosensitive side chain polymer that exhibits liquid crystallinity in a predetermined temperature range, that is, It is a polymer film. And the side chain couple | bonded with the principal chain of a polymer has photosensitivity, and can raise | generate a crosslinking reaction, an isomerization reaction, or a light fleece rearrangement in response to light.

The photosensitive group bonded to the main chain is not particularly limited, but a structure that causes a crosslinking reaction or photofleece rearrangement in response to light is desirable. In this case, the realized 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 that can exhibit liquid crystallinity in a predetermined temperature range used in the method for producing a liquid crystal alignment film of the present invention is not particularly limited as long as it satisfies such characteristics. The side chain structure of the side chain polymer preferably has a rigid mesogen component. In this case, stable liquid crystal alignment can be obtained when the side chain polymer is used for the liquid crystal alignment film.
Examples of such a side chain polymer structure include a main chain and a side chain bonded to the main chain, and the side chain is a biphenyl group, a terphenyl group, a phenylcyclohexyl group, a phenylbenzoate group, an azobenzene group, or the like. The structure has a mesogenic component and a photosensitive group bonded to the tip, which undergoes a crosslinking reaction or an isomerization reaction in response to light, or a main chain and a side chain bonded to the main chain, and the side chain is A structure having a phenylbenzoate group that also serves as a mesogenic component and undergoes a photo-Fries rearrangement reaction can be obtained.

In the following, the photosensitive side chain polymer film capable of exhibiting liquid crystallinity used in the method for producing a liquid crystal alignment film of the present invention will be described. Sometimes referred to as a molecular film, or simply referred to as a side chain polymer film of the present invention.

Specific examples of the photosensitive side chain polymer film capable of exhibiting liquid crystallinity of the present invention include acrylate, methacrylate, maleimide, α-methylene-γ-butyrolactone, siloxane, itaconate, fumarate, maleate, styrene, vinyl, A main chain composed of at least one selected from the group consisting of maleimide, norbornene, polyamic acid, polyimide, polyurea, polyamide, polyether, and polyamic acid ester, and the following formulas (1) to (5), It preferably has a structure having at least one type of side chain selected from the group consisting of formula (7) and formula (8).

In the above formula (1), A ₁ and B ₁ each independently represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—. To express.
Y ₁ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded to them are independent of each other. In addition, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group may be substituted.
X ₁ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —.
l1 represents an integer of 1 to 12, m1 represents an integer of 1 to 3, and n1 represents an integer of 1 to 12.

In the above formula (2), A ₂ , B ₂ , and D ₁ are each independently a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—. Represents CO-.
Y ₂ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded thereto are independent of each other. In addition, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group may be substituted.
X ₂ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —.
R ₁ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
l2 represents an integer of 1 to 12, m2 represents an integer of 1 to 3, and n2 represents an integer of 1 to 12.

In the above formula (3), A ₃ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—.
X ₃ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —, and R ₂ represents a hydrogen atom or a carbon number. Represents an alkyl group of 1 to 6;
l3 represents an integer of 1 to 12, and m3 represents an integer of 1 to 3.
In the above formula (4), l4 represents an integer of 1 to 12.

In the above formula (5), A ₄ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—.
X ₄ represents —COO—.
Y ₃ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, or a combination thereof, and a hydrogen atom bonded thereto is independently —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group may be substituted.
l5 represents an integer of 1 to 12, and m4 represents an integer of 1 to 3.

In the above formula (7), A ₅ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—.
R ₃ is a hydrogen atom, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group having 1 to 6 carbon atoms, or an alkyloxy group having 1 to 6 carbon atoms. Or a group consisting of a combination thereof.
l6 represents an integer of 1 to 12.
The hydrogen atom bonded to the benzene ring in formula (7) is independently —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyl group. It may be substituted with an oxy group.

In the above formula (8), A ₆ represents a single bond, —O—, —CH ₂ —, —COO—, —OCO—, —CONH—, or —NH—CO—.
B ₃ represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C ₆ H ₄ —.
W ₁ is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded thereto are independent of each other. In addition, —NO ₂ , —CN, —CH═C (CN) ₂ , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group may be substituted.
l7 represents an integer of 1 to 12, and m ₅ and m ₆ each independently represents an integer of 1 to 3.

The side chain represented by the above formula (1) to formula (5), formula (7), and formula (8) has a structure having a group such as biphenyl, terphenyl, phenylcyclohexyl, phenylbenzoate, or azobenzene as a mesogenic component Is provided. 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 a phenylbenzoate group that undergoes a photo-Fries rearrangement reaction, or at least one group.

The photosensitive side-chain polymer film capable of exhibiting liquid crystallinity according to the present invention includes the group consisting of the above formulas (1) to (5), (7), and (8) together with the above-described main chain. In addition to at least one type of side chain selected from the above, a side chain structure having no photoreactivity may be used in combination as long as liquid crystallinity and photoreactivity are not lost.
An example of a side chain structure that does not have photoreactivity includes a structure represented by the following formula (6).

<Polysiloxane (a)>
The polysiloxane (a) having a radical polymerizable group used for forming a photosensitive side chain polymer film capable of exhibiting liquid crystallinity used in the method for producing a liquid crystal alignment film of the present invention will be described.

The polysiloxane (a) used as the material for the side chain polymer film is a polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the following formula (10).
R ¹³ _s1 Si (OR ¹⁴ ) _s2 (10)

In the above formula (10), R ¹³ is an alkyl group substituted with an acryl group, a methacryl group, a styryl group, or an aryl group.
R ¹⁴ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.
S1 is 1 or 2, and S2 is 2 or 3.
R ^{13 of the} alkoxysilane represented by the above formula (10) (hereinafter also referred to as a second specific organic group) is at least one selected from the group consisting of an acryl group, a methacryl group, a styryl group, and an aryl group. An alkyl group substituted with The number of substituted hydrogen atoms is one or more, preferably one.
The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms. More preferably, it is 1-10. The alkyl group may be linear or branched, but is more preferably linear.

R ¹⁴ of the alkoxysilane represented by the above formula (10) is an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, and particularly preferably 1 to 2 carbon atoms.

Although the specific example of the alkoxysilane represented by the said Formula (10) is given, it is not limited to these.
Examples of the alkoxysilane represented by the above formula (10) include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, 3- Acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, acryloxyethyltrimethoxysilane, acryloxyethyltriethoxysilane, styrylethyltrimethoxysilane, styrylethyltriethoxysilane, 3- (N-styrylmethyl- 2-aminoethylamino) propyltrimethoxysilane.

In addition to the alkoxysilane represented by the above formula (10), the effects of the present invention are not impaired in the production of the polysiloxane (a) for the purpose of improving the adhesion to the substrate and the affinity with the liquid crystal molecules. As long as it exists, the alkoxysilane represented by following formula (11) can also use 1 type or multiple types. Since the alkoxysilane represented by the following formula (11) can impart various characteristics to the polysiloxane, one or more kinds can be selected and used according to the required characteristics.

(R ¹⁸ ) _n Si (OR ¹⁹ ) _4-n (11)

In the above formula (11), R ¹⁸ is a hydrogen atom or a carbon atom having 1 to 10 carbon atoms which may be substituted with a hetero atom, a halogen atom, an amino group, a glycidoxy group, a mercapto group, an isocyanate group or a ureido group. It is a hydrogen group.

In the above formula (11), R ¹⁹ is an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms.
In the above formula (11), n is an integer of 0 to 3, preferably 0 to 2.

R ¹⁸ of the alkoxysilane represented by the above formula (11) is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms (hereinafter also referred to as a third specific organic group).

Examples of the third specific organic group include an aliphatic hydrocarbon group; a hydrocarbon group having a ring structure such as an aliphatic ring, an aromatic ring and a heterocyclic ring; a hydrocarbon group having an unsaturated bond; and an oxygen atom, It is a hydrocarbon group having 1 to 6 carbon atoms which may contain a hetero atom such as a nitrogen atom or a sulfur atom, and may have a branched structure. In addition, the third specific organic group may be substituted with a halogen atom, an amino group, a glycidoxy group, a mercapto group, an isocyanate group, a ureido group, or the like.

Specific examples of the alkoxysilane represented by the above formula (11) are given below, but the invention is not limited thereto. 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, 2- (2-aminoethylthioethyl) triethoxy Silane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, vinyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, trifluoropropyltrimethoxysilane, chloropropyltriethoxysilane, bromopropyltriethoxysilane, 3- Mercaptopropyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiet Sisilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldimethylethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane and γ-ureidopropyltripropoxysilane Etc.

In the alkoxysilane represented by the above formula (11), the alkoxysilane in which n is 0 is tetraalkoxysilane. Tetraalkoxysilane is preferable for obtaining the polysiloxane (a) used in the present invention because it easily condenses with the alkoxysilane represented by the formula (10).

In the formula (11), as the alkoxysilane in which n is 0, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, or tetrabutoxysilane is more preferable, and tetramethoxysilane or tetraethoxysilane is particularly preferable.

In the present invention, the alkoxysilane represented by the formula (10) is contained in 1 to 30 mol%, particularly preferably 5 to 20 mol% in the total alkoxysilane used for the production of the polysiloxane (a). preferable.

<Monomer (b)>
The monomer (b) used for the formation of the photosensitive side chain polymer film capable of exhibiting liquid crystallinity used in the method for producing a liquid crystal alignment film of the present invention is a liquid crystalline and photosensitive group. And a radically polymerizable group.

The liquid crystalline and photosensitive group of the monomer (b) is derived from at least one selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. It is a group.
For example, the monomer (b) includes a polymerizable group composed of at least one selected from the group consisting of hydrocarbon, acrylate, methacrylate, maleimide and α-methylene-γ-butyrolactone, and the above formulas (1) to It is preferable that it is a monomer which has at least 1 sort (s) of side chain selected from the group which consists of (5), Formula (7), and Formula (8).

The monomer (b) can be used together with the above-described polysiloxane (a) to form a polymer, and can be used for forming the side chain polymer film of the present invention.

<Manufacture of side chain polymer>
The side chain polymer in the side chain polymer film of the present invention comprises the above-described polysiloxane (a) and a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group. A polymer obtained by radical polymerization is included.
The polymer is, for example, in a solvent in which a polysiloxane (a), a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group, and a polymerization initiator coexist. It can be obtained by polymerization reaction at a temperature of 50 to 110 ° C.
The amount of the monomer (b) used is preferably 0.5 to 50 mol, and more preferably 1 to 10 mol, relative to 1 mol of alkoxysilane when the polysiloxane (a) is obtained.

When obtaining the polymer, the solvent used is a polysiloxane (a), a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group, and a polymerization initiator added as necessary. If it dissolves etc., it will not be specifically limited.

Specific examples of the solvent include, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate. , Propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-butanone, 3-methyl-2-pentanone, 2-pentanone, 2-heptanone, γ-butyrolactone, ethyl 2-hydroxypropionate, Ethyl 2-hydroxy-2-methylpropionate, ethoxyacetic acid Chill, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, pyruvate Examples include ethyl, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone and the like.

Examples of the polymerization initiator described above include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- ( Organic peroxides such as azo compounds such as 4-methoxy-2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, t-butylperoxypivalate, 1,1′-bis- (t-butylperoxy) cyclohexane And hydrogen peroxide. Among them, for example, azobisisobutyronitrile (AIBN) is preferable.

The content of the polymerization initiator is preferably 3 to 50 mol%, more preferably 5 to 30 mol%, relative to 1 mol of the monomer (b) described above.

<Method for producing liquid crystal alignment film>
Next, the manufacturing method of the liquid crystal aligning film of this invention is demonstrated.

The method for producing a liquid crystal alignment film of the present invention forms a coating film on a substrate using the above-mentioned side chain polymer, and then irradiates polarized ultraviolet rays. Next, high efficiency anisotropy is introduced into the side chain polymer film by performing the first heating, and further fixing by the second heating to provide excellent liquid crystal alignment control ability. The liquid crystal alignment film provided is manufactured.

More specifically, by utilizing the principle of molecular reorientation induced by photoreaction and liquid crystallinity in the side chain polymer of the side chain polymer film described above, the side chain polymer film is used. To introduce highly efficient anisotropy into
Further, in the method for producing a liquid crystal alignment film of the present invention, in the case of a structure having a photocrosslinkable group as a photoreactive group of a side chain polymer, a coating film is formed on the substrate using the side chain polymer. After that, the first alignment treatment is performed by irradiating polarized ultraviolet rays, and then the first heating (both the first heat treatment is performed) at a temperature within a range in which the side chain type polymer film exhibits liquid crystallinity. And the re-orientation process to be the second alignment process is performed.

Then, after performing the re-orientation treatment, the second heating (also referred to as second heat treatment) is further performed at a temperature equal to or higher than the temperature of the first heating described above, and the polysiloxane structure portion contained therein Is condensed. The second heat treatment can produce a highly efficient liquid crystal alignment film by fixing the anisotropy introduced into the side chain polymer film by light irradiation and the first heat treatment. And In addition, a highly reliable liquid crystal alignment film based on a polysiloxane structure can be provided.

More specifically, the method for producing the liquid crystal alignment film of the present invention includes:
[I]; a step of forming a photosensitive side chain polymer film exhibiting liquid crystallinity in a predetermined temperature range on a substrate;
[II]; a step of irradiating the side chain polymer film obtained in the step [I] with polarized ultraviolet rays;
[III] a step of heating the side chain polymer film irradiated with ultraviolet rays polarized in the step [II], and [IV]; a side chain polymer film heated in the step [III] of the step [III]. And further heating at a different temperature from
It is comprised.

Hereinafter, the present invention using a side chain polymer having a structure having a photocrosslinkable group as a photoreactive group is referred to as a first embodiment, and the side chain polymer having a structure having a photofleece rearrangement group as a photoreactive group. The present invention using this is referred to as a second embodiment, and FIGS. 1 (a) to (d), FIGS. 2 (a) to (d), FIGS. 3 (a) to (c), and FIGS. Further description will be given with reference to (c).

In the method for producing a liquid crystal alignment film according to the first embodiment of the present invention shown in FIGS. 1 (a) to 1 (d), the irradiation with ultraviolet rays in the step [II] is performed by introducing anisotropy into the side chain polymer film. When the amount is in the range of 1 to 15% of the ultraviolet irradiation amount that maximizes ΔA, first, the side chain type polymer film 1 of the present invention is formed on the substrate. As shown in FIG. 1A, the side chain polymer film 1 formed on the substrate has a structure in which the side chains 2 are randomly arranged. According to the random arrangement of the side chain 2 of the side chain polymer film 1, the mesogenic component and the photosensitive group of the side chain 2 are also randomly oriented, and the side chain polymer film 1 is isotropic.
Here, ΔA 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 polarized ultraviolet rays in the side chain polymer film of the present invention.

In the method for producing a liquid crystal alignment film according to the first embodiment of the present invention shown in FIGS. 2 (a) to (d), the irradiation with ultraviolet rays in the step [II] is performed by introducing anisotropy into the side chain polymer film. When the amount is in the range of 15 to 70% of the ultraviolet irradiation amount that maximizes ΔA, first, the side chain type polymer film 3 of the present invention is formed on the substrate. As shown in FIG. 2A, the side chain polymer film 3 formed on the substrate has a structure in which the side chains 4 are randomly arranged. According to the random arrangement of the side chain 4 of the side chain polymer film 3, the mesogenic component and the photosensitive group of the side chain 4 are also randomly oriented, and the side chain polymer film 2 is isotropic.

In the method for producing a liquid crystal alignment film according to the second embodiment of the present invention shown in FIGS. 3A to 3C, anisotropy is introduced into the side chain polymer film, and the above formula (7) is used. In the case where a liquid crystal alignment film using a side chain type polymer having a structure having a photo-fleece rearrangement group is used, the ultraviolet irradiation amount in the step [II] is 1 to the ultraviolet irradiation amount that maximizes ΔA. When it is within the range of 70%, first, the side chain polymer film 5 is formed on the substrate. As shown in FIG. 3A, the side chain polymer film 5 formed on the substrate has a structure in which the side chains 6 are randomly arranged. According to the random arrangement of the side chain 6 of the side chain polymer film 5, 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.

In the method for producing a liquid crystal alignment film according to the second embodiment of the present invention shown in FIGS. 4A to 4C, anisotropy is introduced into the side chain polymer film. In the case where a liquid crystal alignment film using a side chain type polymer having a structure having a photo-fleece rearrangement group is used, the ultraviolet irradiation amount in the step [II] is 1 to the ultraviolet irradiation amount that maximizes ΔA. When it is within the range of 70%, first, the side chain polymer film 7 is formed on the substrate. As shown in FIG. 4A, the side chain type polymer film 7 of this embodiment formed on the substrate has a structure in which the side chains 8 are randomly arranged. According to the random arrangement of the side chains 8 of the side chain polymer film 7, the mesogenic components and the photosensitive groups of the side chains 8 are also randomly oriented, and the side chain polymer film 7 is isotropic.

In the first embodiment of the present invention shown in FIGS. 1A to 1D, in the case where the ultraviolet ray irradiation amount in the step [II] is within the range of 1 to 15% of the ultraviolet ray irradiation amount that maximizes ΔA. The isotropic side chain polymer film 1 is irradiated with polarized ultraviolet rays. Then, as shown in FIG. 1 (b), among the side chains 2 arranged in a direction parallel to the polarization direction of ultraviolet rays, the photosensitive group of the side chain 2a having a photosensitive group is preferentially dimerized. Causes a photoreaction such as 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.

In the first embodiment of the present invention shown in FIGS. 2A to 2D, in the case where the ultraviolet ray irradiation amount in the step [II] is within the range of 15 to 70% of the ultraviolet ray irradiation amount that maximizes ΔA. The isotropic side chain polymer film 3 is irradiated with polarized ultraviolet rays. Then, as shown in FIG. 2 (b), among the side chains 4 arranged in a direction parallel to the polarization direction of the ultraviolet light, the photosensitive group of the side chain 4a having a photosensitive group is preferentially dimerized. Causes a photoreaction such as 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.

3 (a) to 3 (c), a liquid crystal alignment film using a side chain polymer having a structure having an optical fleece rearrangement group represented by the above formula (7) in the second embodiment of the present invention. In the case where the ultraviolet irradiation amount in the step [II] is in the range of 1 to 70% of the ultraviolet irradiation amount that maximizes ΔA, the isotropic side chain polymer film 5 is Irradiate polarized ultraviolet light. Then, as shown in FIG. 3 (b), among the side chains 6 arranged in a direction parallel to the polarization direction of the ultraviolet light, the photosensitive group of the side chain 6a having a photosensitive group is preferentially subjected to photofleece rearrangement. Causes a photoreaction such as 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.

4 (a) to 4 (c), a liquid crystal alignment film using a side chain polymer having a structure having an optical fleece rearrangement group represented by the above formula (8) in the second embodiment of the present invention. In the case where the ultraviolet irradiation amount in the step [II] is in the range of 1 to 70% of the ultraviolet irradiation amount that maximizes ΔA, the isotropic side chain polymer film 7 is Irradiate polarized ultraviolet light. Then, as shown in FIG. 4B, among the side chains 8 arranged in a direction parallel to the polarization direction of the ultraviolet light, the photosensitive group of the side chain 8a having a photosensitive group preferentially undergoes optical Fleece rearrangement. Causes a photoreaction such as 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.

Next, in the first embodiment of the present invention shown in FIGS. 1 (a) to 1 (d), the ultraviolet irradiation amount in the step [II] is in the range of 1 to 15% of the ultraviolet irradiation amount that maximizes ΔA. In some cases, the side chain polymer film 1 after irradiation with polarized light is heated to a liquid crystal state. Then, as shown in FIG.1 (c), in the side chain type polymer film 1, the amount of the generated crosslinking reaction differs between the direction parallel to the polarization direction of the irradiated ultraviolet rays and the direction perpendicular thereto. 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 imparted to the side chain polymer film 1. become.

Similarly, in the first embodiment of the present invention shown in FIGS. 2 (a) to 2 (d), the ultraviolet irradiation amount in the step [II] is within the range of 15 to 70% of the ultraviolet irradiation amount that maximizes ΔA. In some cases, the side chain polymer film 3 after irradiation with polarized light is heated to a liquid crystal state. Then, as shown in FIG. 2 (c), in the side chain type polymer film 3, the amount of the generated crosslinking reaction is different between the direction parallel to the polarization direction of the irradiated ultraviolet rays and the direction perpendicular thereto. 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. .

Similarly, in the second embodiment of the present invention shown in FIGS. 3 (a) to (c), a side chain type polymer having a structure having an optical fleece rearrangement group represented by the above formula (7) was used. Using the liquid crystal alignment film, when the ultraviolet irradiation amount in the step [II] is within the range of 1 to 70% of the ultraviolet irradiation amount that maximizes ΔA, Heat to liquid crystal state. Then, as shown in FIG. 3 (c), in the side chain type polymer film 5, the amount of the generated light fleece rearrangement reaction differs between the direction parallel to the polarization direction of the irradiated ultraviolet light and the direction perpendicular thereto. Yes. 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 self-organizes in the direction perpendicular to the polarization direction of the irradiated ultraviolet light. Thus, 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 imparted to the side chain polymer film 5. It will be.

Similarly, in the second embodiment of the present invention shown in FIGS. 4 (a) to (c), a side chain type polymer having a structure having an optical fleece rearrangement group represented by the above formula (8) was used. Using the liquid crystal alignment film, when the ultraviolet irradiation amount in the step [II] is in the range of 1 to 70% of the ultraviolet irradiation amount that maximizes ΔA, Heat to liquid crystal state. Then, as shown in FIG. 4 (c), in the side chain type polymer film 7, the amount of the generated optical fleece rearrangement reaction differs between the direction parallel to the polarization direction of the irradiated ultraviolet rays and the direction perpendicular thereto. Yes. Since the anchoring force of the optical fleece rearrangement 8 (a) is stronger than that of the side chain 8 before the rearrangement, when a certain amount or more of the optical fleece rearrangement occurs, it is self-assembled in a direction parallel to the polarization direction of the irradiated ultraviolet light. The side chain 8 containing the mesogenic component 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. Become.

Furthermore, in the first embodiment of the present invention, the side chain polymer has a polysiloxane structure derived from the above-described polysiloxane (a). Therefore, the side chain polymer membrane of the present invention has a polysiloxane structure after anisotropy is induced by mesogen self-assembly as shown in FIG. 1 (c) and FIG. 2 (c). The anisotropy can be fixed by performing the second heat treatment at a temperature at which a thermal reaction (crosslinking reaction) caused by the above occurs. That is, the side chain type polymer film of the present invention was induced in the orientation direction of the side chain 2b and the side chain 4b by the second heat treatment as shown in FIG. 1 (d) and FIG. 2 (d). , Large anisotropy can be fixed. The temperature of the second heat treatment is preferably a temperature at which a thermal reaction of siloxane occurs, and can be, for example, a temperature of 200 ° C. or higher.

Furthermore, also in the second embodiment of the present invention, the side chain type polymer has a polysiloxane structure derived from the above-described polysiloxane (a). Therefore, the side chain type polymer film of the present invention has a polysiloxane structure after anisotropy is induced by mesogen self-assembly as shown in FIG. 3 (c) and FIG. 4 (c). The anisotropy can be fixed by performing the second heat treatment at a temperature at which a thermal reaction (crosslinking reaction) caused by the above occurs. That is, the side chain type polymer film of the present invention is not shown, but the induced large anisotropy can be fixed by the second heat treatment as in the first embodiment. The temperature of the second heat treatment is preferably a temperature at which a thermal reaction of siloxane occurs as in the first embodiment described above, and can be, for example, a temperature of 200 ° C. or higher.

Therefore, in the method for producing a liquid crystal alignment film of the present invention, the first heat treatment for irradiation and reorientation of polarized ultraviolet rays to the side chain polymer film and the second heat treatment for immobilization are performed. By sequentially performing the above, a liquid crystal alignment film having anisotropy introduced with high efficiency can be obtained.

In the method for producing a liquid crystal alignment film of the present invention, the irradiation amount of polarized ultraviolet rays on the side chain polymer film and the heating temperatures in the first heat treatment and the second heat treatment are made to correspond to the respective purposes. To optimize. Thereby, introduction of anisotropy into the side chain type polymer film can be realized with high efficiency.

The optimum irradiation amount of polarized ultraviolet rays for introducing highly efficient anisotropy into the side chain polymer film of the present invention is that the photopolymerization reaction or photoisomerization reaction of the photosensitive group in the side chain polymer film 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 polymer film of the present invention with polarized ultraviolet rays, a sufficient amount of photoreaction can be obtained when there are few photogroups in the side chain that undergoes photocrosslinking reaction, photoisomerization reaction, or photofleece rearrangement reaction. Not. In that case, sufficient self-organization does not proceed even after heating.
On the other hand, when the side chain type polymer film of the present invention is irradiated with polarized ultraviolet rays to the structure having a photocrosslinkable group, if the photosensitive group of the side chain that undergoes the crosslinking reaction becomes excessive, crosslinking at the side chain is performed. The reaction will proceed too much. In that case, the resulting film may become rigid and hinder the progress of self-assembly by subsequent heating.

In addition, when the side chain type polymer film of the present invention is irradiated with polarized ultraviolet rays to the structure having the light fleece rearrangement group, the side chain type becomes excessive when the side chain photosensitive group that undergoes the light fleece rearrangement reaction becomes excessive. The liquid crystallinity of the polymer film will be too low. In that case, the liquid crystallinity of the obtained film is also lowered, which may hinder the progress of self-assembly due to subsequent overheating.
Furthermore, when irradiating polarized ultraviolet light to a structure having a photofleece rearrangement group, if the amount of ultraviolet light irradiation is too large, the side chain polymer of the present invention is photodegraded and then self-organized by heating. May interfere with progress.

Therefore, in the side chain type polymer film of the present invention, the optimal amount of the side chain photosensitive group that undergoes photocrosslinking reaction, photoisomerization reaction, or photofries rearrangement reaction by irradiation with polarized ultraviolet rays is the side chain type. The amount is preferably 0.1 to 40 mol%, more preferably 0.1 to 20 mol% of the photosensitive group of the polymer film. 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 high-efficiency anisotropy can be formed in the film. It becomes.

In the method for producing a liquid crystal alignment film of the present invention, by optimizing the irradiation amount of polarized ultraviolet rays, photocrosslinking reaction or photoisomerization reaction of a photosensitive group or photofleece rearrangement in the side chain of the side chain polymer film Optimize the amount of reaction. 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 rays can be determined based on the evaluation of ultraviolet absorption of the side chain polymer film.

That is, with respect to the side chain polymer film of the present invention, the ultraviolet absorption in the direction parallel to the polarization direction of the polarized ultraviolet light and the ultraviolet absorption in the vertical direction after irradiation with polarized ultraviolet light are measured. 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 of ΔA (ΔAmax) realized in the side chain type polymer film of the present invention and the irradiation amount of polarized ultraviolet rays for realizing it are obtained.
In the method for producing a liquid crystal alignment film according to 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 irradiation amount of polarized ultraviolet rays that realizes this ΔAmax.

In the method for producing a liquid crystal alignment film of the present invention, the irradiation amount of polarized ultraviolet rays to the side chain polymer film is preferably in the range of 1 to 70% of the amount of polarized ultraviolet rays that realizes ΔAmax. More preferably, it is in the range of ˜50%.
In the side chain type polymer film of the present invention, 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% of the entire photosensitive group of the side chain type polymer film. 1 to 20 mol% corresponds to the amount of polarized ultraviolet light that undergoes a photocrosslinking reaction.

Next, in the method for producing a liquid crystal alignment film of the present invention, the side chain polymer film is irradiated with polarized ultraviolet rays, and then the side chain polymer film is heated (first heat treatment).
The side chain polymer film of the present invention is a polymer film that can exhibit liquid crystallinity in a predetermined temperature range.
The first 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. That is, the heating temperature of the first heat treatment after irradiation with polarized ultraviolet rays is set to a temperature within a range in which the side chain polymer film of the present invention exhibits liquid crystallinity. The heating temperature after irradiation with polarized ultraviolet rays ranges from a temperature 10 ° C. higher than the lower limit of the temperature range in which the side chain polymer film of the present invention exhibits liquid crystallinity (hereinafter referred to as a liquid crystal temperature range). The temperature is preferably in the range up to 10 ° C. lower than the upper limit.

The side-chain polymer film of the present invention is heated after irradiation with polarized ultraviolet rays to be in a liquid crystal state, and is self-organized and reoriented in a direction parallel to or perpendicular to the polarization direction. As a result, the small anisotropy of the side chain polymer film induced by the photocrosslinking reaction, photoisomerization reaction, or 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 in the range from the lower limit of the liquid crystal temperature range of the side chain polymer film of the present invention to a temperature higher by 10 ° C., the anisotropic amplification effect due to heat in the side chain polymer film can be obtained. However, it cannot be enough.

Further, even if the side chain polymer film of the present invention exhibits a liquid crystal state by heating, if the heating temperature is high, the state of the side chain polymer film becomes close to an isotropic liquid state, and self-organization This makes it difficult to reorient in one 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 of the present invention, the anisotropic amplification effect due to heat in the side chain polymer film can be obtained. However, it cannot be enough.

Furthermore, even if the heating temperature of the first heat treatment is higher than the temperature lower by 10 ° C. than the upper limit of the liquid crystal temperature range of the side chain polymer film of the present invention, for example, the reaction of siloxane such as 200 ° C. or higher. When the temperature is higher than the temperature, the thermal reaction of the siloxane portion may proceed before realignment. In that case, it becomes difficult to reorient the side chain polymer film in one direction due to self-organization. For example, when the heating temperature is higher than 200 ° C., the anisotropic amplification effect due to heat in the side chain polymer film cannot be made sufficient.

As described above, in the method for producing a liquid crystal alignment film of the present invention, the liquid crystal temperature range of the side chain polymer film and the reaction of the siloxane part are realized in order to realize highly efficient anisotropy into the side chain polymer film. A suitable heating temperature is determined based on the temperature range. As described above, the heating temperature after irradiation with polarized ultraviolet rays is lower than the lower limit of the liquid crystal temperature range of the side chain type polymer film by 10 ° C., and is 200 ° C. or lower, which is higher than the upper limit of the liquid crystal temperature range. The temperature is within a range where the upper limit is a temperature 10 ° C lower. Therefore, for example, when the liquid crystal temperature range of the side chain polymer film of the present invention is 100 ° C. to 200 ° C. and the siloxane portion reacts at a temperature higher than 200 ° C., the heating temperature after irradiation with polarized ultraviolet rays is set to 110 to 190. Desirably, the temperature is set to ° C. By so doing, greater anisotropy is imparted to the side chain polymer film.

Next, each step of the method for producing a liquid crystal alignment film of the present invention will be described more specifically.

As described above, the method for producing a liquid crystal alignment film of the present invention includes the following steps [1] to [IV] in the following order. Thereby, a liquid crystal alignment film into which anisotropy is introduced can be manufactured with high efficiency.
[I]; a step of forming a photosensitive side chain polymer film exhibiting liquid crystallinity in a predetermined temperature range on a substrate;
[II]; a step of irradiating the side chain polymer film obtained in the step [I] with polarized ultraviolet rays;
[III]; a step of heating the side chain polymer film irradiated with ultraviolet rays polarized in step [II]; and [IV]; a side chain polymer film heated in step [III] of step [III]. A step of further heating at a temperature equal to or higher than the heating temperature of III].

Hereinafter, each step [I] to [IV] of the method for producing a liquid crystal alignment film of the present invention will be described.

In step [I], the side chain polymer film of the present invention is formed on a substrate.
The substrate is not particularly limited. For example, in addition to a glass substrate, a transparent substrate such as a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used. In consideration of application of the obtained liquid crystal alignment film, a substrate on which an ITO (Indium Tin Oxide) electrode or the like for driving a liquid crystal is formed is used from the viewpoint of simplifying the process of manufacturing a liquid crystal display element. Is also possible. In consideration of application to a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can also be used. In this case, an electrode using a material that reflects light such as aluminum can be used.

When the side chain polymer film of the present invention is in the form of a solution dissolved in a desired solvent, film formation on the substrate is performed by applying the solution-like side chain polymer film.
The coating method is not particularly limited, but industrially, a method performed by screen printing, offset printing, flexographic printing, 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), a spray method, and the like, and these may be used depending on the purpose.

After the solution-like side chain polymer film of the present invention is coated on the substrate, it is 20 to 180 ° C., preferably 40 to 150 ° C., by a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven. By evaporating the solvent at 0 ° C., a side chain polymer membrane can be obtained.
If the thickness of the side chain polymer film is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element to which the liquid crystal alignment film is applied, and if it is too thin, the reliability of the liquid crystal display element may be lowered. The thickness is 5 to 300 nm, more preferably 10 to 100 nm.

In addition, it is also possible to provide the process of cooling the board | substrate with which the side chain type polymer film was formed to room temperature after process [I] and before subsequent process [II].

In the step [II], the first alignment treatment is performed by irradiating the side chain polymer film obtained in the step [I] with polarized ultraviolet rays. When irradiating the surface of the 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 100 to 400 nm can be used. Preferably, the optimum wavelength is selected through a filter or the like depending on the type of the side chain polymer film to be used. For example, ultraviolet rays 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.

As described above, the irradiation amount of the polarized ultraviolet ray is preferably in the range of 1 to 70% of the amount of the polarized ultraviolet ray that realizes ΔAmax of the side chain polymer film of the present invention to be used. More preferably, it is within the range of 50%.

In the step [III], as the first heat treatment, the side chain polymer film irradiated with the ultraviolet rays polarized in the step [II] is heated. For the heat treatment, heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, or the like is used.
As described above, the heating temperature can be determined in consideration of the temperature at which the liquid crystallinity of the side chain polymer film of the present invention is exhibited. That is, the heating temperature in this step is a temperature at which reorientation occurs in the side chain polymer film.

The heating temperature in this step after irradiation with polarized ultraviolet rays in step [II] is 200 ° C. or less, with the temperature being 10 ° C. higher than the lower limit of the liquid crystal temperature range in which the side chain polymer film of the present invention exhibits liquid crystallinity. And it is preferable that it is the temperature of the range which makes temperature 10 degreeC lower than the upper limit of a liquid-crystal temperature range an upper limit. The side chain type polymer film of the present invention can exhibit liquid crystallinity, and is preferably set to 60 ° C. or higher and 180 ° C. or lower as a temperature range that does not cause thermal reaction.

In step [IV], as the second heat treatment, the side chain polymer film heated in step [III] is further heated at a temperature different from the heating temperature in step [III]. Step [III] is a temperature at which the side chain polymer film of the present invention is brought into a liquid crystal state, and a temperature within a range that does not cause a thermal reaction of the siloxane portion is selected and heat treatment (first heat treatment ) Has been made. Therefore, in this step, a heating temperature higher than the heating temperature in step [III] is selected, and the heat treatment (second heat treatment) is performed. The heating temperature in this step is a temperature for fixing the reorientation of the side chain polymer film in step [III].

In the heat treatment, heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, or the like can be used as in the step [III].
As described above, the heating temperature can be determined in consideration of the reaction temperature of the siloxane moiety in the side chain polymer film of the present invention. For example, the heating temperature in this step is preferably 200 ° C. or higher. Moreover, it is preferable to set it as the temperature of 300 degrees C or less with less fear of thermal degradation of a side chain type polymer film, especially the temperature of 250 degrees C or less.

By having the above steps, the method for producing a liquid crystal alignment film of the present invention can realize the introduction of anisotropy into the side chain polymer film with high efficiency.
Furthermore, the liquid crystal alignment film of the present invention with high efficiency and high reliability can be manufactured.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not construed as being limited to these.
Abbreviations and structures of compounds and organic solvents used in the following synthesis examples, examples and comparative examples are shown below.

(Silane monomer)
TEOS: Tetraethoxysilane ACPS: 3-acryloxypropyltrimethoxysilane (methacrylate monomer)

(Organic solvent)
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve PGME: Propylene glycol monomethyl ether (polymerization initiator)
AIBN: Azobisisobutyronitrile

<Molecular weight measurement>
The number average molecular weight and weight average molecular weight of the acrylic copolymer were measured using a GPC apparatus (Shodex (registered trademark) columns KF803L and KF804L) manufactured by JASCO Corporation, and the elution solvent tetrahydrofuran was supplied at a flow rate of 1 mL (milliliter) / min. It was measured under the condition that it was eluted by flowing through (column temperature 40 ° C.). The following number average molecular weight (hereinafter referred to as Mn) and weight average molecular weight (hereinafter referred to as Mw) were expressed in terms of polystyrene.

<Synthesis of polysiloxane>
<Synthesis Example 1>
Polysiloxane (A): PGME (15.6 g), TEOS (18.8 g), and ACPS (2.3 g) were charged into a four-necked reaction flask equipped with a reflux tube and stirred at room temperature for 10 minutes. . Then, a mixture of PGME (7.8 g), oxalic acid (0.1 g), and H ₂ O (5.4 g) was added dropwise to this solution. After the dropwise addition, the mixture was heated to reflux for 3 hours and then allowed to cool to room temperature. After cooling, it was diluted with PGME (50 g) to prepare a polysiloxane (A) solution.

[Measurement of residual alkoxysilane monomer]
The residual alkoxysilane monomer in the prepared polysiloxane (A) solution was measured by gas chromatography (hereinafter referred to as GC).
The GC measurement was performed under the following conditions using Shimadzu GC-14B manufactured by Shimadzu Corporation.

Column: Capillary column CBP1-W25-100 (length 25 mm, diameter 0.53 mm, wall thickness 1 μm)
Column temperature: The temperature was raised from a starting temperature of 50 ° C. at 15 ° C./min to reach an ultimate temperature of 290 ° C. (holding time 3 minutes).
Sample injection volume: 1 μL, injection temperature: 240 ° C., detector temperature: 290 ° C., carrier gas: nitrogen (flow rate 30 mL / min), detection method: FID method.

As a result of the measurement, no alkoxysilane monomer was detected in the polysiloxane (A) solution.

<Synthesis of polysiloxane-polymethacrylate hybrid and preparation of liquid crystal aligning agent>
<Synthesis Example 2>
Add 1.0 g of polysiloxane (A) obtained in Synthesis Example 1, 2 g (3.9 mmol) of M6CB and 0.08 g (0.47 mmol) of AIBN as a polymerization initiator to 20 ml of NMP, and dissolve all solids at room temperature. The reaction system was purged with nitrogen, and then the reaction temperature was gradually raised, followed by stirring at 50 ° C. for 15 hours (hours). After completion of the reaction, the reaction solution was poured into 500 ml of diethyl ether to separate the polymer. After removing AIBN, the precipitate was separated by filtration to obtain a polysiloxane-polymethacrylate hybrid (P6CBS) powder (B).

When this P6CBS powder (B) was observed while raising the temperature under a polarizing microscope, liquid crystallinity was exhibited in a temperature range of 60 to 300 ° C. or higher. Thereafter, when P6CBS was continuously heated at 300 ° C., the condensation reaction of siloxane proceeded, P6CBS became a thermoset, and the liquid crystallinity was gradually lost. The phase transition behavior of this polysiloxane-polymethacrylate hybrid (P6CBS) is summarized in Table 1.

<Synthesis Example 3>
2.5 g of polysiloxane (A) obtained in Synthesis Example 1, 2 g (6.0 mmol) of M6CA and 0.13 g (0.79 mmol) of AIBN as a polymerization initiator were added to 22 ml of NMP, and all solids were dissolved at room temperature. The reaction system was purged with nitrogen, and then the reaction temperature was gradually raised, and the reaction was carried out by stirring at 50 ° C. for 15 hours. After completion of the reaction, the reaction solution was poured into 500 ml of diethyl ether to separate the polymer, and after removing AIBN, the precipitate was separated by filtration to obtain polysiloxane-polymethacrylate hybrid (P6CAS) powder (C).

When this P6CBS powder (C) was observed while raising the temperature under a polarizing microscope, it exhibited liquid crystallinity at 80 to 190 ° C. Subsequently, when P6CAS was continuously heated to 200 ° C. or higher, the condensation reaction of siloxane proceeded, and P6CAS became a thermoset and the liquid crystallinity was lost. The phase transition behavior of this polysiloxane-polymethacrylate hybrid (P6CAS) is summarized in Table 1.

<Example 1>
NMP and BCS were added to the polysiloxane-polymethacrylate hybrid (P6CBS) (powder (B)) obtained in Synthesis Example 2 and diluted to 4% by mass to obtain a liquid crystal aligning agent (I). Abnormalities such as turbidity and precipitation were not observed in this liquid crystal alignment treatment agent, and it was confirmed that the resin component was uniformly dissolved. When the molecular weight of P6CBS was measured by measuring this liquid crystal aligning agent with GPC, Mn was 35000.

[Measurement method of siloxane content in hybrid polymer]
The siloxane content in the polysiloxane-polymethacrylate hybrid (powder (B)) was calculated from GPC. The siloxane content was calculated by comparing the peak ratio of the methacrylate monomer on the GPC chart after radical polymerization with the peak ratio of the polysiloxane-polymethacrylate hybrid.
The calculated siloxane-methacrylate ratio in P6CBS was 1: 5 by weight.

<Example 2>
NMP and BCS were added to the polysiloxane-polymethacrylate hybrid (P6CAS) (powder (C)) obtained in Synthesis Example 3 and diluted to 4% by mass to obtain a liquid crystal aligning agent (II). Abnormalities such as turbidity and precipitation were not observed in this liquid crystal alignment treatment agent, and it was confirmed that the resin component was uniformly dissolved. When the molecular weight of P6CAS was measured by measuring this liquid crystal aligning agent by GPC, Mn was 48000. The siloxane-methacrylate ratio of P6CAS calculated from GPC was 2: 3.5 by weight.

<Manufacture of liquid crystal alignment film>
<Example 3>
The liquid crystal alignment treatment agent (I) containing the polysiloxane-polymethacrylate hybrid (P6CBS) obtained in Example 1 was spin-coated on a quartz substrate (length 10 × width 10 × thickness 1 (mm)). After drying for 5 minutes on a hot plate at 80 ° C., a coating film with a film thickness of 50 nm was formed to obtain a substrate with a liquid crystal alignment film before the alignment treatment.

<Example 4>
The substrate with a liquid crystal alignment film before alignment treatment obtained in Example 3 was used to irradiate polarized ultraviolet rays through a polarizing plate from a certain direction with respect to the liquid crystal alignment film surface on the substrate. The intensity of the polarized ultraviolet light was 14 mW at a wavelength of 365 nm, and the ultraviolet irradiation amount was 600 mJ. Then, this ultraviolet-irradiated substrate is heated at 150 ° C. for 5 minutes, and the coating film (polymer film) is subjected to a realignment treatment by changing the P6CBS of the coating film to a liquid crystal state. A substrate was obtained. The obtained substrate with a liquid crystal high film was used for measurement of an ultraviolet absorption spectrum (FIG. 5) as described later.

<Example 5>
The substrate with a liquid crystal alignment film before alignment treatment obtained in Example 3 was used to irradiate polarized ultraviolet rays through a polarizing plate from a certain direction with respect to the liquid crystal alignment film surface on the substrate. The intensity of the polarized ultraviolet light was 14 mW at a wavelength of 365 nm, and the ultraviolet irradiation amount was 600 mJ. Then, this ultraviolet-irradiated board | substrate was heated at 150 degreeC for 5 minute (s), and the reorientation process was performed to the coating film by making P6CBS of a coating film into a liquid-crystal state. Subsequently, the substrate subjected to the re-orientation treatment was heated to 200 ° C., and baked at that temperature for 15 minutes to cause condensation reaction of siloxane, thereby fixing the orientation. In this way, an alignment-treated substrate with a liquid crystal alignment film was obtained.

<Example 6>
The substrate with a liquid crystal alignment film before alignment treatment obtained in Example 3 was used to irradiate polarized ultraviolet rays through a polarizing plate from a certain direction with respect to the liquid crystal alignment film surface on the substrate. The intensity of the polarized ultraviolet light was 14 mW at a wavelength of 365 nm, and the ultraviolet irradiation amount was 800 mJ. Then, this ultraviolet-irradiated substrate was heated at 150 ° C. for 5 minutes, and the P6CBS of the coating film was brought into a liquid crystal state, so that the coating film was subjected to a realignment treatment to obtain an alignment-treated substrate with a liquid crystal alignment film.
The obtained substrate with a liquid crystal high film was used for measurement of an ultraviolet absorption spectrum (FIG. 6) as described later.

<Example 7>
The substrate with a liquid crystal alignment film before alignment treatment obtained in Example 3 was used to irradiate polarized ultraviolet rays through a polarizing plate from a certain direction with respect to the liquid crystal alignment film surface on the substrate. The intensity of the polarized ultraviolet light was 14 mW at a wavelength of 365 nm, and the ultraviolet irradiation amount was 800 mJ. Then, this ultraviolet-irradiated board | substrate was heated at 150 degreeC for 5 minute (s), and the reorientation process was performed to the coating film by making P6CBS of a coating film into a liquid-crystal state. Subsequently, the substrate subjected to the re-orientation treatment was heated to 200 ° C., and baked at that temperature for 15 minutes to cause condensation reaction of siloxane, thereby fixing the orientation. In this way, an alignment-treated substrate with a liquid crystal alignment film was obtained.

<Evaluation of liquid crystal alignment film>
<Example 8>
Using the alignment-treated substrate with a liquid crystal alignment film obtained in Example 4, the ultraviolet absorption spectrum of the liquid crystal alignment film was measured.

FIG. 5 is a UV absorption spectrum parallel and perpendicular to the polarized electric field vector of the irradiated UV of the liquid crystal alignment film obtained in Example 4.

In FIG. 5, the ultraviolet absorption spectrum of the liquid crystal alignment film obtained in Example 4 (shown as “parallel after heating” and “vertical after heating” in the figure) is shown. The ultraviolet absorption spectra (shown as “parallel after polarized light irradiation” and “perpendicular after polarized light irradiation” in the figure) of the liquid crystal alignment film made (before the heat treatment of Example 4) are shown.

As shown in FIG. 5, when comparing the ultraviolet absorption spectrum of the liquid crystal alignment film of Example 4 with the ultraviolet absorption spectrum of the substrate subjected to only polarized ultraviolet irradiation (before the heat treatment of Example 4), The ultraviolet absorption spectrum was irradiated on the substrate in which the difference between the ultraviolet absorption spectrum in the parallel direction and the vertical direction with respect to the polarization electric field of the irradiated polarized ultraviolet light was only irradiated with the polarized ultraviolet light (before the heat treatment in Example 4). The difference in ultraviolet absorption spectrum between the parallel direction and the perpendicular direction to the polarization electric field of the polarized ultraviolet light is larger, and the liquid crystal alignment film obtained in Example 4 is realigned by heating after irradiation with polarized ultraviolet light. You can see that it was done.

FIG. 6 is an ultraviolet absorption spectrum parallel and perpendicular to the polarized electric field vector of the irradiated ultraviolet rays of the liquid crystal alignment film obtained in Example 6.

6 also shows the ultraviolet absorption spectrum of the liquid crystal alignment film obtained in Example 6 (shown as “parallel after heating” and “perpendicular after heating” in the figure). (Before the heat treatment of Example 6) UV absorption spectra of the liquid crystal alignment film (shown as “parallel after polarized light irradiation” and “perpendicular after polarized light irradiation” in the figure) are shown.

As shown in FIG. 6, even in the liquid crystal alignment film obtained in Example 6, as with the liquid crystal alignment film obtained in Example 4, the polarized electric field of the irradiated polarized ultraviolet light is changed by heating after irradiation with polarized ultraviolet light. On the other hand, the difference between the parallel UV absorption and the UV absorption in the vertical direction is only irradiated with polarized UV light (before the heat treatment in Example 4), and the direction parallel to and perpendicular to the polarization electric field of the irradiated polarized UV light. It can be seen that the liquid crystal alignment film obtained in Example 6 was realigned by heating after irradiation with polarized UV light.

<Manufacture of liquid crystal cells>
<Example 9>
A liquid crystal alignment film was prepared using the liquid crystal alignment treatment agent (I) obtained in Example 1, and a liquid crystal cell using the liquid crystal alignment film was manufactured. The liquid crystal cell was a parallel aligned liquid crystal cell corresponding to the characteristics of the liquid crystal alignment film. A liquid crystal display element can be constituted by sandwiching the obtained liquid crystal cell between a pair of polarizing plates.

As a method for producing a liquid crystal cell, a liquid crystal alignment treatment agent (I) is spin-coated on a glass substrate with an ITO electrode, dried on a hot plate at 80 ° C. for 5 minutes, and then a liquid crystal alignment film as a coating film having a thickness of 50 nm. And a substrate with a liquid crystal alignment film before the alignment treatment was obtained. The liquid crystal alignment films formed on the substrate were all excellent in film thickness uniformity, and the liquid crystal alignment treatment agent (I) was found to exhibit excellent coating properties.

The obtained substrate with a liquid crystal alignment film before the alignment treatment was used to irradiate polarized ultraviolet rays through a polarizing plate from a certain direction with respect to the liquid crystal alignment film surface on the substrate. The intensity of the polarized ultraviolet light was 14 mW at a wavelength of 365 nm, and the ultraviolet irradiation amount was 600 mJ. Then, this ultraviolet-irradiated board | substrate was heated at 150 degreeC for 5 minute (s), and the reorientation process was performed to the coating film by making P6CBS of a coating film into a liquid-crystal state. Subsequently, the substrate subjected to the re-orientation treatment was heated at 250 ° C. and baked at that temperature for 15 minutes to cause a condensation reaction of siloxane, thereby fixing the orientation. In this way, an alignment-treated substrate with a liquid crystal alignment film was obtained.

Two substrates with this liquid crystal alignment film were prepared, a 14 μm spacer was placed on one liquid crystal alignment film surface, and a sealing agent was applied from above. Subsequently, after bonding together so that the other board | substrate and the liquid crystal aligning film surface might face each other, the sealing compound was hardened and the empty cell was produced. By utilizing capillary action, nematic liquid crystal (ZLI-4792 manufactured by Merck & Co., Inc.) was injected into the empty cell at 105 ° C., which is higher than the isotropic phase temperature of the liquid crystal, to obtain a liquid crystal cell.

<Example 10>
A liquid crystal cell was produced according to the same method as in Example 9 except that the irradiation amount of polarized ultraviolet rays was 800 mJ.

<Evaluation of liquid crystal display element>
<Example 11>
Using the liquid crystal cells obtained in Example 9 and Example 10, the alignment state of the liquid crystal was evaluated using a polarizing microscope. That is, a liquid crystal cell was sandwiched between a pair of polarizing plates using a polarizing microscope, and a liquid crystal display element was constructed and evaluated. In any liquid crystal cell, there was no alignment defect, and a good alignment state of the liquid crystal was observed. The evaluation results are summarized in Table 2.

In the present invention, a polymer and a liquid crystal aligning agent suitable for producing a highly efficient liquid crystal aligning film using light are provided, and the liquid crystal aligning film and the liquid crystal display element obtained from the liquid crystal aligning agent are lightweight, thin and It can be used as a display device with low power consumption.
It should be noted that the entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2012-163898 filed on July 24, 2012 is cited here as the disclosure of the specification of the present invention. Incorporated.

1, 3, 5, 7 Side chain

type polymer membrane

2, 2a, 2b, 4, 4a, 4b, 6, 6a, 8, 8a

Claims

Forming a photosensitive side chain polymer film that exhibits liquid crystallinity in a predetermined temperature range on a substrate [I],
Irradiating the side chain type polymer film with polarized ultraviolet rays [II],
The step [III] of heating the side chain polymer film irradiated with ultraviolet rays at a temperature within a range where the side chain polymer film exhibits liquid crystallinity, and the heated side chain polymer film Step [IV] for further heating at a temperature equal to or higher than the heating temperature in Step [III]
A method for producing a liquid crystal alignment film, comprising:
The heating temperature in the step [III] is in a range from a temperature 10 ° C. higher 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 liquid crystal temperature range. The manufacturing method of the liquid crystal aligning film of Claim 1.
The heating temperature of process [III] is a manufacturing method of the liquid crystal aligning film of Claim 1 or 2 which is the temperature of 200 degrees C or less.
The method for producing a liquid crystal alignment film according to any one of claims 1 to 3, wherein the heating temperature in the step [III] is a temperature at which the side chain of the side chain polymer film is reoriented.
The heating temperature in the step [III] is a temperature at which the side chain of the side chain polymer film is reoriented, and the heating temperature in the step [IV] is a temperature for fixing the reorientation in the step [III]. The method for producing a liquid crystal alignment film according to any one of claims 1 to 4.
The photosensitive group contained in the photosensitive side chain polymer film exhibiting liquid crystallinity is selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. 6. The method for producing a liquid crystal alignment film according to claim 1, wherein the liquid crystal alignment film is a group derived from at least one kind.
The side chain polymer film includes a main chain composed of at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, acrylate, methacrylate, maleimide, α-methylene-γ-butyrolactone and siloxane. The structure having at least one side chain selected from the group consisting of the following formulas (1) to (5), (7), and (8): The manufacturing method of the liquid crystal aligning film of any one.

(In Formula (1), A 1 and B 1 each independently represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. Y 1 represents a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, Independently, it may be substituted with —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group, wherein X 1 is a single bond, — COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —, wherein l1 represents an integer of 1 to 12 and m1 represents 1 to 3 Represents an integer, and n1 represents an integer of 1 to 12.
In the formula (2), A 2 , B 2 , and D 1 are each independently a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO. -Represents. Y 2 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded thereto are each independently , —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. X 2 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. R 1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l2 represents an integer of 1 to 12, m2 represents an integer of 1 to 3, and n2 represents an integer of 1 to 12.
In Formula (3), A 3 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. X 3 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. R 2 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l3 represents an integer of 1 to 12, and m3 represents an integer of 1 to 3.
In the formula (4), l4 represents an integer of 1 to 12.
In Formula (5), A 4 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. X 4 represents —COO—. Y 3 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, or a combination thereof, and a hydrogen atom bonded thereto is independently —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. l5 represents an integer of 1 to 12, and m4 represents an integer of 1 to 3.
In formula (7), A 5 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. R 3 is a hydrogen atom, —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group having 1 to 6 carbon atoms, or an alkyloxy group having 1 to 6 carbon atoms. Or a group consisting of a combination thereof. l6 represents an integer of 1 to 12. The hydrogen atom bonded to the benzene ring in formula (7) is independently —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyl group. It may be substituted with an oxy group.
In Formula (8), A 6 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. B 3 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. W 1 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or 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 alkyloxy group. l7 represents an integer of 1 to 12, and m 5 and m 6 each independently represents an integer of 1 to 3. )
The side chain polymer film radically polymerizes a polysiloxane (a) having a radically polymerizable group and a monomer (b) having a liquid crystalline and photosensitive group and a radically polymerizable group. The method for producing a liquid crystal alignment film according to any one of claims 1 to 7, comprising a polymer formed as described above.
The liquid crystalline and photosensitive group of the monomer (b) is derived from at least one selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. The method for producing a liquid crystal alignment film according to claim 8, which is a group.
A liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film according to any one of claims 1 to 9.
A liquid crystal display element having the liquid crystal alignment film according to claim 10.
A polymer obtained by radical polymerization of a polysiloxane (a) having a radical polymerizable group and a monomer (b) having a liquid crystalline and photosensitive group and a radical polymerizable group.
The polymer according to claim 12, wherein the polysiloxane (a) is a polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane of the following formula (10).
R 13 s1 Si (OR 14 ) s2 (10)
(In Formula (10), R 13 represents an alkyl group substituted with an acryl group, a methacryl group, a styryl group, or an aryl group. R 14 represents hydrogen or an alkyl group having 1 to 5 carbon atoms. S1 Is 1 or 2, and S2 is 2 or 3.)
The liquid crystalline and photosensitive group of the monomer (b) is derived from at least one selected from the group consisting of azobenzene, stilbene, cinnamic acid, cinnamic acid ester, chalcone, coumarin, tolan and phenylbenzoate. The polymer according to claim 12 or 13, which is a group.
The monomer (b) includes a polymerizable group composed of at least one selected from the group consisting of acrylate, methacrylate, maleimide and α-methylene-γ-butyrolactone, and the following formulas (1) to (5), The polymer according to any one of claims 12 to 14, which is a monomer having at least one side chain selected from the group consisting of formula (7) and formula (8).

(In Formula (1), A 1 and B 1 each independently represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. Y 1 represents a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, Independently, it may be substituted with —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group, wherein X 1 is a single bond, — COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —, wherein l1 represents an integer of 1 to 12 and m1 represents 1 to 3 Represents an integer, and n1 represents an integer of 1 to 12.
In the formula (2), A 2 , B 2 , and D 1 are each independently a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO. -Represents. Y 2 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or a combination thereof, and the hydrogen atoms bonded thereto are each independently , —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. X 2 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. R 1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l2 represents an integer of 1 to 12, m2 represents an integer of 1 to 3, and n2 represents an integer of 1 to 12.
In Formula (3), A 3 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. X 3 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. R 2 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. l3 represents an integer of 1 to 12, and m3 represents an integer of 1 to 3.
In the formula (4), l4 represents an integer of 1 to 12.
In Formula (5), A 4 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. X 4 represents —COO—. Y 3 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, or a combination thereof, and a hydrogen atom bonded thereto is independently —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyloxy group. l5 represents an integer of 1 to 12, and m4 represents an integer of 1 to 3.
In formula (7), A 5 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. R 3 is a hydrogen atom, —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group having 1 to 6 carbon atoms, or an alkyloxy group having 1 to 6 carbon atoms. Or a group consisting of a combination thereof. l6 represents an integer of 1 to 12. The hydrogen atom bonded to the benzene ring in formula (7) is independently —NO 2 , —CN, —CH═C (CN) 2 , —CH═CH—CN, a halogen group, an alkyl group, or an alkyl group. It may be substituted with an oxy group.
In Formula (8), A 6 represents a single bond, —O—, —CH 2 —, —COO—, —OCO—, —CONH—, or —NH—CO—. B 3 represents a single bond, —COO—, —OCO—, —N═N—, —CH═CH—, —C≡C—, or C 6 H 4 —. W 1 is a group selected from a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a cyclic hydrocarbon having 5 to 8 carbon atoms, or 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 alkyloxy group. l7 represents an integer of 1 to 12, and m 5 and m 6 each independently represents an integer of 1 to 3. )
The weight according to any one of claims 12 to 15, wherein the amount of the monomer (b) used is 0.5 to 50 moles relative to 1 mole of the alkoxysilane when the polysiloxane (a) is obtained. Coalescence.
A liquid crystal aligning agent containing the polymer according to any one of claims 12 to 16.