WO2013146589A1

WO2013146589A1 - Liquid crystal display element and manufacturing method therefor

Info

Publication number: WO2013146589A1
Application number: PCT/JP2013/058303
Authority: WO
Inventors: 達哉名木; 宏之桜井; 皇晶筒井
Original assignee: 日産化学工業株式会社
Priority date: 2012-03-30
Filing date: 2013-03-22
Publication date: 2013-10-03
Also published as: TW201345951A; JPWO2013146589A1; KR20140139115A; CN104335112A; TWI499616B

Abstract

A liquid crystal display element (1) is configured so that a TFT substrate (2) and a CF substrate (3) provided with a CF layer (7) sandwich a liquid crystal layer (4). The TFT substrate (2) and the CF substrate (3) are provided with a liquid crystal alignment film (12). In the liquid crystal display element (1), a sealing material (16) uses a UV ray curable resin, and even in the regions where pixels are formed, UV rays for curing the sealing material (16) are radiated and provided. The liquid crystal display element (1) is configured using the liquid crystal alignment film (12) which contains a polyimide film synthesized from a diamine compound of a specific structure. When the sealing material (16) is cured, even if the regions where pixels are formed are irradiated with UV rays, the degradation of functionality is suppressed.

Description

Liquid crystal display element and manufacturing method thereof

The present invention relates to a liquid crystal display element and a manufacturing method thereof.

The liquid crystal display element is configured by sandwiching and encapsulating a liquid crystal layer between a pair of substrates and aligning the liquid crystal of the liquid crystal layer in a certain direction. The alignment of the liquid crystal is realized by providing a liquid crystal alignment film having a liquid crystal alignment control ability on the substrate surface. In a liquid crystal display element, a liquid crystal responds by applying a voltage to an electrode disposed between a substrate and a liquid crystal alignment film, and uses a change in the alignment of the liquid crystal to change a desired image in an image forming region. Display can be made. The liquid crystal display element can provide a thin, lightweight and high-quality display device.

In the manufacture of a liquid crystal display element, a frame-shaped sealing material disposed on a substrate is used as a method for enclosing a liquid crystal forming a liquid crystal layer between a pair of substrates. Then, a vacuum injection method, a drop injection method, or the like is used, and liquid crystal is injected into the inside of the frame-shaped sealing material, and a liquid crystal layer is sealed between the substrates. Of the liquid crystal injection methods described above, the drop injection method (see Patent Document 1) is a preferred method in recent years because it is effective in reducing the amount of liquid crystal used.

In the dropping injection method, first, an ultraviolet curable sealing material is formed in a frame shape around one substrate, and in a vacuum atmosphere, liquid crystal is dropped on the substrate in the sealing material frame, and the liquid crystal is dropped. The prepared substrate and the other substrate are bonded together. Next, it is returned to the atmosphere, and the liquid crystal between both substrates bonded together is diffused by atmospheric pressure. Then, the sealing material is irradiated with ultraviolet rays, the sealing material is cured, and the liquid crystal is sealed.

Further, in the manufacture of the liquid crystal display element, as a method for aligning the liquid crystal in the liquid crystal layer in a certain direction, as described above, a method of providing a liquid crystal alignment film having a liquid crystal alignment control ability on the substrate surface is used. The liquid crystal alignment film is formed by subjecting a polymer film such as polyimide formed on the substrate to an alignment process such as a rubbing process or a photo-alignment process performed by irradiating polarized ultraviolet rays.

The rubbing treatment for the liquid crystal alignment film means that the surface of the substrate is rubbed (rubbed) with a cloth such as cotton, nylon or polyester against the organic film such as polyimide on the substrate. This is a treatment method for orienting liquid crystal. Since this rubbing treatment can easily realize a relatively stable alignment state of liquid crystals, it has been used in the manufacturing process of conventional liquid crystal display elements.

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

Therefore, in recent years, an optical alignment process without rubbing has been actively studied (see Patent Document 2).
There are various methods for photo-alignment treatment. 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. As light, ultraviolet rays can be preferably used. This photo-alignment treatment does not require rubbing, can constitute a liquid crystal display element without concern about dust generation, etc., and can achieve the desired liquid crystal alignment.

Japanese Patent Laid-Open No. 11-109388 Japanese Patent No. 4504665

As described above, the liquid crystal display element provides a thin, lightweight, high-quality display device. In the manufacture of the liquid crystal display element, as a main process, a process of encapsulating a liquid crystal material between substrates and an alignment process for aligning the liquid crystal A process is included. In recent years, a process for irradiating light such as ultraviolet rays has been studied and effectively utilized. Such a process using light irradiation improves the problems of the manufacturing process such as the conventional vacuum injection method and rubbing process, and is effective in improving the production efficiency and the manufacturing yield.

However, on the other hand, in the case where a light irradiation process, particularly a light irradiation process for irradiating ultraviolet rays, is provided during the manufacturing process of the liquid crystal display element, the charge retention characteristics of the liquid crystal display element may be lowered and the display quality may be lowered. .

For example, when performing the dropping injection method in liquid crystal injection / encapsulation, when the sealing material is irradiated with ultraviolet rays, the liquid crystal alignment film in the image forming region may be irradiated with ultraviolet rays. In such a case, in the manufactured liquid crystal display element, the charge retention characteristic is lowered, and the display quality of the image may be lowered.

Further, when performing the photo-alignment treatment, the liquid crystal alignment film may be provided with a liquid crystal alignment control ability using polarized ultraviolet rays. In such a case, in the manufactured liquid crystal display element, although the alignment of the liquid crystal is realized, the charge retention characteristic is lowered and the display quality of the image may be lowered.

Therefore, even if manufactured using a process of performing light irradiation treatment with ultraviolet rays, such as a drop injection method or a photo-alignment treatment, which has been actively studied in recent years, without reducing the performance such as charge retention characteristics, There is a need for a liquid crystal display element that does not cause deterioration in display quality.

Therefore, an object of the present invention is to provide a liquid crystal display element that is manufactured by performing light irradiation treatment with ultraviolet rays and in which deterioration of display quality is suppressed.

Another object of the present invention is to provide a method for manufacturing a liquid crystal display element, which performs a light irradiation treatment with ultraviolet rays and manufactures a liquid crystal display element in which deterioration of display quality is suppressed.

It should be noted that other objects and advantages of the present invention will become apparent from the following description.

In the first aspect of the present invention, at least one layer selected from a polyimide precursor formed using a compound represented by the following formula (1) and a polyimide obtained by imidizing the polyimide is formed in a pixel formation region. Having a liquid crystal alignment film containing coalescence,
A liquid crystal display element, wherein the pixel formation region is configured by irradiating with ultraviolet rays.

In the first aspect of the present invention, the liquid crystal alignment film excludes a compound represented by the above formula (1) and a compound represented by the following formula (AM) (a compound represented by the above formula (1)). And at least one polymer selected from polyimides obtained by imidizing it.

(In Formula (AM), Y ₁ is a divalent organic group, and two or more types may be present. In Formula (AM), R ¹ and R ² are a hydrogen atom or a monovalent group. Represents an organic group.)

In the first aspect of the present invention, the liquid crystal alignment film is obtained by imidizing a polyimide precursor formed using at least one of the compounds represented by the following formulas (CB1) to (CB5). It is preferable that the polymer contains at least one polymer selected from polyimides.

(In the formulas (CB1) to (CB5), Z ₁ is a tetravalent organic group having 4 to 13 carbon atoms and contains a non-aromatic cyclic hydrocarbon group having 4 to 6 carbon atoms. Formula (CB4) In (CB5), R ³ represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms.)

A second aspect of the present invention is a method of manufacturing a liquid crystal display element having a liquid crystal layer and a liquid crystal alignment film in a pixel formation region,
Forming the liquid crystal alignment film containing at least one polymer selected from a polyimide precursor formed using a compound represented by the following formula (1) and a polyimide obtained by imidizing the same in a pixel formation region A liquid crystal alignment film forming step,
The present invention relates to a method of manufacturing a liquid crystal display element, comprising a light irradiation step of irradiating a pixel formation region with ultraviolet rays after the liquid crystal alignment film formation step.

In the second aspect of the present invention, the liquid crystal alignment film excludes a compound represented by the above formula (1) and a compound represented by the following formula (AM) (a compound represented by the above formula (1). And at least one polymer selected from polyimides obtained by imidizing it.

In the second aspect of the present invention, the liquid crystal alignment film is obtained by imidizing a polyimide precursor formed using at least one of the compounds represented by the following formulas (CB1) to (CB5). It is preferable that the polymer contains at least one polymer selected from polyimides.

In the second aspect of the present invention, after the liquid crystal alignment film forming step, the method includes a seal forming step of forming a sealant around the pixel formation region,
The light irradiation step is preferably a step of curing the sealing material in the seal forming step.

In the second aspect of the present invention, the light irradiation step is preferably a step of aligning the liquid crystal alignment film.

In the second aspect of the present invention, the method includes a step of forming a liquid crystal layer in a pixel formation region after the liquid crystal alignment film formation step,
The light irradiation step is preferably a step of irradiating the pixel formation region with ultraviolet light while driving the liquid crystal of the liquid crystal layer.

In the second aspect of the present invention, the liquid crystal layer comprises a liquid crystal and a photopolymerizable compound,
The light irradiation step is preferably a step of polymerizing the photopolymerizable compound in the liquid crystal layer in the pixel formation region.

According to the first aspect of the present invention, it is possible to provide a liquid crystal display element that is manufactured by performing a light irradiation process for irradiating ultraviolet rays and in which deterioration of display quality is suppressed.

According to the second aspect of the present invention, it is possible to provide a method for manufacturing a liquid crystal display element, which performs a light irradiation process for irradiating ultraviolet rays, and manufactures a liquid crystal display element in which deterioration of display quality is suppressed.

It is sectional drawing which shows typically the structure of the liquid crystal display element of embodiment of this invention.

In the manufacture of a liquid crystal display element, as described above, the main steps include a step of encapsulating liquid crystals between substrates and an alignment treatment step of a liquid crystal alignment film for aligning liquid crystals. In such a process, a desired effect is realized by curing a photocurable sealing material using light, particularly visible light or ultraviolet irradiation, or performing a photoalignment treatment of the liquid crystal alignment film. be able to.

In addition, in a PSA (Polymer Sustained Alignment) type liquid crystal display element, a liquid crystal to which a small amount (typically 0.2 wt% to 1 wt%) of a photopolymerizable compound is added is used to sandwich the liquid crystal. The ultraviolet rays are irradiated in a state where a voltage is applied between the electrodes of both substrates. As a result, in the PSA type liquid crystal display element, the photopolymerizable compound reacts, polymerizes and crosslinks by such ultraviolet irradiation treatment, so that the response speed of the liquid crystal display element is increased.

Further, a liquid crystal display element of a type manufactured by irradiating ultraviolet rays with a voltage applied between the electrodes of both substrates sandwiching the liquid crystal (hereinafter referred to simply as an ultraviolet irradiation method in this specification). There is.) This ultraviolet irradiation type liquid crystal display element is a VA (Vertical Alignment) mode liquid crystal display element in which the initial alignment of the liquid crystal is vertical alignment, and as described above, a voltage is applied between the electrodes of both substrates sandwiching the liquid crystal. Manufactured by irradiating ultraviolet rays in an applied state. As the liquid crystal display element of the ultraviolet irradiation method, a liquid crystal in which a small amount of a photopolymerizable compound is added can be used. An ultraviolet irradiation type liquid crystal display element can realize excellent response characteristics of liquid crystal.

As described above, the liquid crystal display element can realize desired characteristics by including light irradiation, particularly ultraviolet irradiation treatment in its manufacturing process. However, on the other hand, it has been found that it can cause problems. That is, in the conventional liquid crystal display element, the characteristics may be deteriorated by receiving light, particularly ultraviolet rays, in the formation region of the pixel that performs image display. Specifically, upon receiving irradiation of ultraviolet rays, the charge retention characteristics (for example, charge retention ratio) may be lowered, or the residual DC characteristics may be lowered.

Therefore, as a result of intensive studies, the present inventors have found that it is effective in solving such problems by optimizing the structure of the liquid crystal alignment film of the liquid crystal display element.
In the liquid crystal display element, as described above, a highly heat-resistant and high-strength polyimide film is frequently used as a liquid crystal alignment film for aligning liquid crystals.

And when forming the polyimide film used as a liquid crystal aligning film on the board | substrate which comprises a liquid crystal display element, the method of using the following liquid crystal aligning agents is used suitably.
As the method, as described above, a liquid crystal aligning agent containing a polyimide precursor such as polyamic acid is prepared. And the method of forming the coating film using the obtained liquid crystal aligning agent, imidizing on a board | substrate, and obtaining a polyimide film is known. As another method, a polyimide that has been imidized in advance is dissolved in a solvent to prepare a solvent-soluble liquid crystal aligning agent. And there exists a method of forming a coating film using the liquid crystal aligning agent, and obtaining a polyimide film.

The present inventors have found that by optimizing the molecular structure of such a polyimide-based liquid crystal alignment film, it is possible to reduce the above-described problems caused by irradiation with light, particularly ultraviolet rays. That is, the inventors of the present invention are liquid crystal display elements that are created through a process of irradiating the pixel formation region with light, particularly ultraviolet rays, and are selected from a polyimide precursor having an optimal structure and a polyimide obtained by imidizing it. Thus, a liquid crystal display element having a liquid crystal alignment film containing at least one polymer and having reduced performance deterioration with respect to irradiation with light, particularly ultraviolet rays, was obtained, and the present invention was achieved.
Hereinafter, embodiments of the present invention will be described.

Embodiment 1
The liquid crystal display element which is the 1st Embodiment of this invention is demonstrated using drawing.
As an example, the liquid crystal display element of the present embodiment can be a color liquid crystal display element of a TN (Twisted Nematic) mode.

In that case, the liquid crystal display element of the present embodiment includes, for example, a CF substrate including a TFT substrate on which a thin film transistor (TFT) is disposed, and a color filter layer (hereinafter also referred to as a CF layer). And a sealing material is disposed around a pixel formation region for image formation, and the substrate is fixed between the substrates.
Hereinafter, the structure of the liquid crystal display element of this embodiment will be described in more detail.

FIG. 1 is a cross-sectional view schematically illustrating the structure of the liquid crystal display element of this embodiment.

A liquid crystal display element 1 shown in FIG. 1 is an example of the liquid crystal display element according to the first embodiment of the present invention, and as described above, a transmissive TN mode liquid crystal display element driven by TFTs can be used. The liquid crystal display element 1 is configured by sandwiching a liquid crystal layer 4 between the above-described TFT substrate 2 and a CF substrate 3 having a CF layer 7.

As shown in FIG. 1, the TFT substrate 2 of the liquid crystal display element 1 has a TFT (not shown) and a transparent pixel electrode 6 made of ITO or the like formed in a matrix on the liquid crystal layer 4 side of the transparent substrate 5. Configured. For example, the TFT substrate 2 includes a plurality of gate lines (not shown) provided on the substrate 5 so as to extend in parallel to each other, a gate insulating film (not shown) provided so as to cover each gate line, and a gate insulating film on the gate insulating film. A plurality of source lines (not shown) provided so as to extend in parallel with each other in a direction perpendicular to each gate line, and a plurality of gate lines and each intersection of the source lines, that is, a plurality of each provided for each pixel The TFT includes an interlayer insulating film provided so as to cover each TFT and each source line, and a plurality of pixel electrodes 6 formed in a matrix on the interlayer insulating film and connected to each TFT.

The CF substrate 3 of the liquid crystal display element 1 is configured by arranging the CF layer 7 and the protective layer 8 on the liquid crystal layer 4 side of the transparent substrate 15. The CF layer 7 has a red, green and blue colored layer 9 provided at a position facing the pixel electrode 6 of the TFT substrate 2 and a black matrix 10 provided between the colored layers 9 to block light. Configured. A transparent common electrode 11 made of ITO or the like is disposed on the protective layer 8 on the CF layer 7 of the CF substrate 3.

The TFT substrate 2 and the CF substrate 3 are each provided with a liquid crystal alignment film 12 on the surface in contact with the liquid crystal layer 4. The liquid crystal alignment film 12 can be a liquid crystal alignment film 12 configured using a polyimide film having a desired structure, which will be described in detail later. In the liquid crystal display element 1, when necessary, the liquid crystal alignment film 12 is subjected to an alignment process such as a rubbing process, whereby a uniform alignment in the liquid crystal layer 4 sandwiched between the TFT substrate 2 and the CF substrate 3 is achieved. realizable.

The liquid crystal display element 1 of the present embodiment can be a TN mode liquid crystal display element. The liquid crystal layer 4 is made of nematic liquid crystal and exhibits a twist alignment state of 90 degrees between the TFT substrate 2 and the CF substrate 3 by the action of the liquid crystal alignment film 12.

In the TFT substrate 2 and the CF substrate 3, polarizing plates 17 are respectively disposed on the outer surface opposite to the liquid crystal layer 4 side. The distance (also referred to as a gap) between the TFT substrate 2 and the CF substrate 3 is preferably 1 μm to 20 μm, and the gap is fixed and maintained by a sealant 16 provided in the peripheral portion of the pixel electrode 6 arrangement region. ing.

The seal material 16 is provided with a pixel frame 6 and is provided in a rectangular frame shape so as to surround the periphery of a pixel formation region for displaying an image. The frame width of the sealing material 16 is not particularly limited, but can be set to 0.5 mm or more and 2.0 mm or less, for example. As a sealing material for forming the sealing material 16, for example, an ultraviolet curable resin such as an acrylic resin, a urethane resin, a polyester resin, and an epoxy resin can be used. These resins may be used alone or in combination of two or more.

In the liquid crystal display element 1, the sealing material 16 uses, for example, an ultraviolet curable resin and is cured by being irradiated with ultraviolet rays. Therefore, the liquid crystal display element 1 is also provided with irradiation of ultraviolet rays for curing the sealing material 16 in the pixel formation region as well.

As described above, in the liquid crystal display element 1 irradiated with ultraviolet rays even in the pixel formation region, one pixel is formed for each pixel electrode 6, and a voltage of a predetermined magnitude is applied to the liquid crystal layer 4 in each pixel. Thereby, the alignment state of the liquid crystal of the liquid crystal layer 4 is changed, and for example, the transmittance of visible light incident from a backlight (not shown) is adjusted to display an image.

The liquid crystal display element 1 having the above structure can be manufactured as follows.
First, the TFT substrate 2 having the above-described structure is prepared. The TFT substrate 2 is manufactured, for example, by forming various electrodes including TFTs and pixel electrodes 6 on a substrate 5 made of a transparent glass substrate or the like according to a known method. Then, a liquid crystal alignment film 12 is formed on the TFT substrate 2. Details of the liquid crystal alignment film 12 and the method of forming the liquid crystal alignment film 12 will be described later.

Then, the CF substrate 3 having the above structure is prepared. The CF substrate 3 is formed, for example, by patterning the CF layer 7 having the colored layer 9 and the black matrix 10, the common electrode 11 and the like on the substrate 15 made of a transparent glass substrate or the like. Then, a liquid crystal alignment film 12 is formed on the surface of the common electrode 11. The black matrix is made of a metal material such as Ta (tantalum), Cr (chromium), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), Al (aluminum), or a black pigment such as carbon. Are dispersed or a resin material in which a plurality of colored layers having light transmittance are laminated.

Next, around the region where the pixel electrode 6 of the TFT substrate 2 is formed, an ultraviolet curable sealing material is used, a dispenser method, a method of printing in a desired shape, or a spin coating method. After the coating, the sealing material 16 is formed in a frame shape according to a patterning method using a photolithography method. Next, in a vacuum atmosphere, liquid crystal is dropped onto the TFT substrate 2 within the frame of the sealing material 16 and the TFT substrate 2 and the CF substrate 3 onto which the liquid crystal has been dropped are bonded together. Next, the TFT substrate 2 and the CF substrate 3 and their state are returned to the atmosphere, and the liquid crystal between the TFT 2 substrate and the CF substrate 3 bonded together is diffused by atmospheric pressure to form the liquid crystal layer 4. Then, the sealing material 16 is irradiated with ultraviolet rays to cure the sealing material 16. Then, the polarizing plate 17 is arrange | positioned to the surface of the TFT substrate 2 and the external side of the CF substrate 3 opposite to the liquid crystal layer 4, respectively, and the liquid crystal display element 1 is manufactured.

Therefore, in the manufacture of the liquid crystal display element 1 of the present embodiment, the light irradiation step of irradiating ultraviolet rays is a step of curing the sealing material 16, and is a step of fixing the TFT substrate 2 and the CF substrate 3 to each other. The irradiation light has a wavelength characteristic suitable for curing the sealing material 16, and can be an ultraviolet ray having a wavelength of 200 nm to 400 nm. And as for the irradiation amount of an ultraviolet-ray, it is preferable to select the quantity suitable for hardening of a sealing material.

Here, in the light irradiation process in which the sealing material 16 is cured by the ultraviolet irradiation treatment, the ultraviolet light is also applied to the pixel formation region where the pixel electrode 6, the liquid crystal alignment film 12, the liquid crystal layer 4, and the like are disposed together with the sealing material 16. Irradiation has been made. In order not to irradiate the liquid crystal alignment film 12 or the like in the pixel formation region with ultraviolet rays, no other means such as providing a mask having a predetermined shape is taken. Therefore, the light irradiation process is a process of curing the sealing material 16 by irradiating the entire area with ultraviolet rays without dividing the formation area of the sealing material 16 and the formation area of the pixels more easily.

However, the liquid crystal display element 1 of the present embodiment is configured using a liquid crystal alignment film 12 including a polyimide film having a structure to be described later. For this reason, for example, even when the sealing material 16 is cured, even if it is irradiated with ultraviolet rays in the pixel formation region, the deterioration of the performance is suppressed. Therefore, even if the liquid crystal display element 1 of the present embodiment is produced through a process of irradiating the pixel formation region with ultraviolet rays, it can suppress performance degradation due to ultraviolet irradiation, which has been a problem in the past. it can. That is, according to the present embodiment, it is possible to provide the liquid crystal display element 1 that is manufactured using a light irradiation process that irradiates ultraviolet rays and that suppresses the deterioration of display quality.

In the liquid crystal display element 1 of this embodiment, a visible light curable sealing material can be used for forming the sealing material 16. For example, it is possible to use a photocurable resin that is cured by irradiating visible light energy such as an acrylic resin, a methacrylic resin, an epoxy resin, and a silicone resin. Even in such a case, the liquid crystal display element 1 of the present embodiment is configured using the liquid crystal alignment film 12 including a polyimide film having a specific structure to be described later. For example, when the sealing material 16 is cured, Even in the formation region, even if visible light is irradiated, deterioration of performance is suppressed. Therefore, the liquid crystal display element 1 of the present embodiment can suppress performance degradation due to visible light irradiation even when the liquid crystal display element 1 is formed through a process of irradiating visible light to a pixel formation region.

In addition to the above-described TN mode, the liquid crystal display element of the present embodiment includes an STN (Super Twisted Nematic) mode, an IPS (In-Plane Switching) mode, a VA (Vertical Alignment) mode, or an OCB (Optically Compensating Bending). ) Mode or the like. In that case, the TFT substrate and the CF substrate can have a known structure suitable for each liquid crystal mode, unlike the example shown in FIG.

The liquid crystal display element of the present embodiment having the above-described configuration is characterized by being manufactured by being irradiated with ultraviolet rays and suppressing deterioration in display quality. In order to realize such characteristics, a liquid crystal alignment film is important. It becomes a necessary component. Therefore, a liquid crystal alignment film that is a main component of the liquid crystal display element of the present embodiment and is effective in reducing performance deterioration even when irradiated with light such as visible light or ultraviolet light will be described.
The above-described liquid crystal display element 1 of this embodiment in FIG. 1 is a TN mode liquid crystal surface element, but this is an example of this embodiment, and the liquid crystal alignment film described below has an IPS mode or Description will be made so that the liquid crystal display element of this embodiment such as the VA mode also includes a suitable liquid crystal alignment film.

The liquid crystal alignment film of the present embodiment constituting the liquid crystal display element of the present embodiment is preferably a liquid crystal alignment film containing at least one polymer selected from a polyimide precursor and a polyimide obtained by imidizing it. By including such a polymer, the liquid crystal alignment film of this embodiment has excellent durability such as high heat resistance.

The liquid crystal alignment film of this embodiment is an effective liquid crystal alignment film for reducing performance deterioration of the liquid crystal display element even when irradiated with ultraviolet rays. As described above, when a liquid crystal alignment film containing a polymer such as polyimide is formed on a substrate such as a TFT substrate or a CF substrate, a method using a liquid crystal aligning agent is preferable. The liquid crystal aligning agent contains at least one polymer selected from a polyimide precursor obtained by reacting a diamine compound and a tetracarboxylic acid derivative and a polyimide obtained by imidizing it. preferable. Then, a liquid crystal alignment film can be formed by heating a coating film of a liquid crystal aligning agent on a substrate such as a TFT substrate or a CF substrate to form a polymer film such as polyimide, and performing a necessary alignment treatment.

Therefore, the liquid crystal alignment film of this embodiment is preferably formed using the liquid crystal alignment agent of this embodiment. And the liquid crystal aligning agent of this embodiment contains at least 1 sort (s) of polymer chosen from the polyimide precursor and the polyimide obtained by imidating it, and the weight is formed so that the liquid crystal aligning film of the said characteristic may be formed. The structure of coalescence is optimized.
As a result, due to the structural characteristics of the polyimide precursor and the polymer such as polyimide contained in the liquid crystal aligning agent, it is possible to provide a liquid crystal aligning film effective for reducing performance deterioration even when irradiated with ultraviolet rays.

As described above, the polyimide precursor that can be contained in the liquid crystal aligning agent is obtained by reacting a diamine compound and a tetracarboxylic acid derivative, and the polyimide is obtained by imidizing the polyimide precursor. In order for the polyimide precursor contained in the liquid crystal aligning agent of the present embodiment to achieve a desired structure, a diamine compound having a specific structure is preferably selected and used for the synthesis thereof.

That is, the liquid crystal aligning agent of this embodiment is at least one selected from a polyimide precursor obtained by reacting a diamine compound having a specific structure and a tetracarboxylic acid derivative, and a polyimide obtained by imidizing it. The liquid crystal alignment film of this embodiment can be provided.

Next, the diamine compound and tetracarboxylic acid derivative having a specific structure for forming the polyimide precursor and polyimide that can be contained in the liquid crystal aligning agent of the present embodiment will be described in more detail. Then, the polyimide precursor and polyimide will be described in more detail, and the liquid crystal aligning agent of this embodiment containing them and the formation of the liquid crystal alignment film of this embodiment using the same will be described in more detail.
In the present invention, the polyimide precursor includes polyamic acid, polyamic acid ester, and the like.

<Diamine compound>
As a diamine compound having a specific structure suitable for the synthesis of the polyimide precursor contained in the liquid crystal aligning agent of this embodiment for forming the liquid crystal aligning film of this embodiment, a compound represented by the following formula (1) Is used.

As a diamine for reacting with a tetracarboxylic acid derivative and synthesizing a polyimide precursor and a polyimide which can be contained in the liquid crystal aligning agent of this embodiment, only the diamine compound represented by the above formula (1) is used alone. May be used. Also, a combination of the compound represented by the above formula (1) and another diamine compound represented by the following formula (AM) described below, other than the diamine compound represented by the above formula (1) May be used.

<Other diamine compounds>
In order to synthesize a polyimide precursor and a polyimide that can be contained in the liquid crystal aligning agent of this embodiment, as described above, the compound represented by the above formula (1) and the above formula (1) are used. Other than the diamine compound, other diamine compounds represented by the following formula (AM) described below can be used in combination.

In the above formula (AM), Y ₁ is a divalent organic group, and two or more kinds may be mixed. In the formula (AM), R ¹ and R ² represent a hydrogen atom or a monovalent organic group.

More specifically, in the above formula (AM), R ¹ and R ² are each independently a hydrogen atom or an optionally substituted alkyl group, alkenyl group, or alkynyl group having 1 to 10 carbon atoms. is there.

In the above formula (AM), as described above, R ¹ and R ² are each independently a hydrogen atom or an optionally substituted alkyl group, alkenyl group, alkynyl group having 1 to 10 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group, and a bicyclohexyl group. It is done. Examples of the alkenyl group include those obtained by replacing one or more CH—CH structures present in the alkyl group with C═C structures, and more specifically, vinyl groups, allyl groups, 1-propenyl groups. Group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group and the like. Examples of the alkynyl group include those obtained by replacing one or more CH ₂ —CH ₂ structures present in the alkyl group with a C≡C structure, and more specifically, an ethynyl group, a 1-propynyl group, And 2-propynyl group.

The above alkyl group, alkenyl group, and alkynyl group may have a substituent as long as the number of carbon atoms is 1 to 10 as a whole, and may further form a ring structure by the substituent. The formation of a ring structure by a substituent means that the substituents or a substituent and a part of the mother skeleton are bonded to form a ring structure.

In this case, examples of the substituent include halogen groups, hydroxyl groups, thiol groups, nitro groups, aryl groups, organooxy groups, organothio groups, organosilyl groups, acyl groups, ester groups, thioester groups, phosphate ester groups, amides. Groups, alkyl groups, alkenyl groups and alkynyl groups.

Examples of the halogen group as the substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
A phenyl group is mentioned as an aryl group which is the above-mentioned substituent. This aryl group may be further substituted with the other substituent described above.

The organooxy group which is the above-described substituent can have a structure represented by OR. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples of the organooxy group include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.

The organothio group which is the above-described substituent can have a structure represented by —S—R. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the substituent described above. Specific examples of the organothio group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

The organosilyl group which is the above-described substituent can have a structure represented by —Si— (R) ₃ . The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples of the organosilyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a tripentylsilyl group, a trihexylsilyl group, a pentyldimethylsilyl group, and a hexyldimethylsilyl group.

The acyl group which is the above-described substituent can have a structure represented by —C (O) —R. Examples of R include the alkyl groups, alkenyl groups, and aryl groups described above. These Rs may be further substituted with the substituent described above. Specific examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoyl group and the like.

As the ester group which is the above substituent, a structure represented by —C (O) O—R or —OC (O) —R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the substituent described above.
As the thioester group which is the above-described substituent, a structure represented by —C (S) O—R or —OC (S) —R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, and the like. These Rs may be further substituted with the substituent described above.

The phosphate group which is the above-described substituent can have a structure represented by —OP (O) — (OR) ₂ . The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, aryl group described above. These Rs may be further substituted with the substituent described above.
Examples of the amide group as the substituent include —C (O) NH ₂ , or —C (O) NHR, —NHC (O) R, —C (O) N (R) ₂ , —NRC (O ) The structure represented by R can be shown. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above.

Examples of the aryl group that is the above-described substituent include the same aryl groups as described above. This aryl group may be further substituted with the other substituent described above.
Examples of the alkyl group that is the above-described substituent include the same alkyl groups as described above. This alkyl group may be further substituted with the other substituent described above.
Examples of the alkenyl group as the substituent include the same alkenyl groups as described above. This alkenyl group may be further substituted with the other substituent described above.
Examples of the alkynyl group that is the above-described substituent include the same alkynyl group as described above. This alkynyl group may be further substituted with the other substituent described above.

In general, when a bulky structure is introduced, there is a possibility that the reactivity of the amino group and the liquid crystal orientation may be lowered. Therefore, as R ¹ and R ² , a hydrogen atom or an optionally substituted carbon number is 1 An alkyl group of 1 to 5 is more preferable, and a hydrogen atom, a methyl group, or an ethyl group is particularly preferable.

In the above formula (AM), examples of specific structures of Y ₁ include Y-1 to Y-106 shown below, but are not limited thereto.

<Tetracarboxylic acid derivative>
The polyimide precursor that is used for the reaction with the diamine compound described above and can be contained in the liquid crystal aligning agent of this embodiment and the tetracarboxylic acid derivative that synthesizes the polyimide are not particularly limited.

Examples of tetracarboxylic acid derivatives include tetracarboxylic dianhydride (represented by the following formula (CB1)), tetracarboxylic acid monoanhydride (represented by the following formula (CB2)), tetracarboxylic acid ( And a dicarboxylic acid dialkyl ester (represented by the following formula (CB4)), a dicarboxylic acid chloride dialkyl ester (represented by the following formula (CB5)), and the like. As the tetracarboxylic acid derivative, one kind may be used alone, or two or more kinds may be used in combination.

In the above formulas (CB4) and (CB5), R ³ represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms.
In the above formulas (CB1) to (CB5), specific examples of Z ₁ include the following formulas (Z-1) to (Z-46).

The tetracarboxylic acid derivative having the above structure is used for the reaction with the above-described diamine compound, and a polyimide precursor or polyimide having a desired structure is synthesized and contained in the liquid crystal aligning agent to provide the liquid crystal alignment film of this embodiment. A tetracarboxylic acid derivative in which Z ₁ is the formula (Z-1) in the above formulas (CB1) to (CB5) is preferable. The tetracarboxylic acid reacts with the diamine compound having a specific structure represented by the above formula (1) to provide a polyimide precursor having a desired structure, thereby providing a polyimide having a desired structure. And the liquid crystal aligning film of this embodiment effective in reducing performance degradation to a high level even if irradiated with light, such as visible light and an ultraviolet-ray, can be provided. Therefore, when the polyimide precursor that can be contained in the liquid crystal aligning agent of this embodiment or the tetracarboxylic acid derivative that synthesizes polyimide is used alone, Z _{1 in} the above formulas (CB1) to (CB5) It is preferable to use a tetracarboxylic acid derivative which is (Z-1).

<Polyimide precursor>
The polyimide precursor which can be contained in the liquid crystal aligning agent of this embodiment is synthesize | combined using the diamine component which contains the diamine compound of the said Formula (1) as an essential component. The polyimide precursor contained in the liquid crystal aligning agent of this embodiment is a polyamic acid and polyamic acid ester, for example, and has a structural unit represented by a following formula (PA).

In the above formula (PA), Z is an example of the above-described tetracarboxylic acid derivative, tetracarboxylic dianhydride (represented by the above formula (CB1)), tetracarboxylic monoanhydride (the above formula (CB2)). ), Tetracarboxylic acid (represented by the above formula (CB3)), dicarboxylic acid dialkyl ester (represented by the above formula (CB4)), and dicarboxylic acid chloride dialkyl ester (represented by the above formula (CB5)). It is a group derived from Z ₁ group in).
_Ra is a hydrogen atom or a monovalent organic group derived from the above-described tetracarboxylic acid derivative or an esterifying agent described later, preferably having 1 to 5 carbon atoms, more preferably 1 to 1 carbon atoms. Represents an alkyl group of 2;

In the above formula (PA), Y is a group derived from the corresponding group of the diamine compound represented by the above formula (1) and the Y ₁ group of the other diamine compound represented by the above formula (AM). . A ₁ and A ₂ represent a hydrogen atom or a monovalent organic group derived from the R ¹ group and R ² group of the other diamine compound represented by the above formula (AM).

The polyamic acid which is a polyimide precursor includes, for example, a diamine component (hereinafter simply referred to as a diamine component) containing the diamine compound of the above formula (1) as an essential component, and a tetracarboxylic acid derivative described above. Obtained by reaction with carboxylic dianhydride.

As the method for obtaining the polyamic acid contained in the liquid crystal aligning agent of the present embodiment by the reaction of the above-described diamine component and tetracarboxylic dianhydride, a known method can be used. The synthesis method is a method in which a diamine component and tetracarboxylic dianhydride are reacted in an organic solvent. The reaction between the diamine component and tetracarboxylic dianhydride is advantageous in that it proceeds relatively easily in an organic solvent and no by-products are generated.

The organic solvent used for the reaction between the above-described diamine component and tetracarboxylic dianhydride is not particularly limited as long as the generated polyamic acid is soluble. Specific examples are given below.

N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide , Γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl Carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethyl Glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene Glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropiate Lenglycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n- Hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, Ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropio Acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3- Examples thereof include ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like.

These exemplified solvents may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate.

In addition, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

When the above diamine component and tetracarboxylic dianhydride are reacted in an organic solvent, the solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride is used as it is or in an organic solvent. A method of adding by dispersing or dissolving in a solvent, a method of adding a diamine component to a solution in which tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent, and a tetracarboxylic dianhydride and a diamine component alternately. The method of adding etc. is mentioned, You may use any of these methods. In addition, when the diamine component or tetracarboxylic dianhydride is composed of a plurality of types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further reacted individually. May be mixed and reacted to form a high molecular weight product.

The polymerization temperature at that time can be selected from -20 ° C. to 150 ° C., but is preferably in the range of −5 ° C. to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the total concentration of the diamine component and the tetracarboxylic dianhydride in the reaction solution is preferably 1% by mass to 50% by mass, more preferably 5% by mass to 30% by mass. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.

In the polymerization reaction of polyamic acid, the ratio of the total number of moles of tetracarboxylic dianhydride to the total number of moles of the diamine component is preferably 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1.0, the higher the molecular weight of the polyamic acid produced.

<Polyamic acid ester>
The polyimide precursor which can be contained in the liquid crystal aligning agent of this embodiment is a polyamic acid, polyamic acid ester, etc. as mentioned above. The polyamic acid ester which is a polyimide precursor is obtained by using, for example, the following methods (1) to (3) using a diamine component and a tetracarboxylic acid derivative containing the diamine compound represented by the above formula (1) as an essential component. Can be synthesized.

(1) Method of synthesizing from polyamic acid The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from a diamine component and tetracarboxylic dianhydride.
Specifically, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C., for 30 minutes to 24 hours, preferably 1 hour to 4 hours. Can be synthesized.

As the above-mentioned esterifying agent, those that can be easily removed by purification are preferred, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N— Dimethylformamide dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3 -P-tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents relative to 1 mol of the polyamic acid repeating unit.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the solubility of the polymer, and these may be used alone or in combination of two or more. Good. The concentration at the time of synthesis is preferably 1% by mass to 30% by mass and more preferably 5% by mass to 20% by mass from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight product is easily obtained.

(2) Method of synthesizing by reaction of tetracarboxylic acid diester dichloride and diamine component The polyamic acid ester can be synthesized from tetracarboxylic acid diester dichloride and the above-mentioned diamine component.

Specifically, the tetracarboxylic acid diester dichloride and the diamine component are present in the presence of a base and an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 4 It can synthesize | combine by making it react for time.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The addition amount of the base is preferably 2 to 4 times with respect to the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the monomer and polymer. These may be used alone or in combination of two or more. The polymer concentration at the time of synthesis is preferably 1% by mass to 30% by mass and more preferably 5% by mass to 20% by mass from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(3) Method of synthesizing from tetracarboxylic acid diester and diamine component Polyamic acid ester can be synthesized by polycondensation of tetracarboxylic acid diester and the above-mentioned diamine component.

Specifically, tetracarboxylic acid diester and the above-mentioned diamine component are added in the presence of a condensing agent, a base, and an organic solvent at 0 ° C. to 150 ° C., preferably 0 ° C. to 100 ° C., for 30 minutes to 24 hours, preferably It can be synthesized by reacting for 3 to 15 hours.

Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazide. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like. The addition amount of the condensing agent is preferably 2 to 3 times by mole with respect to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 4 times by mole with respect to the diamine component from the viewpoint of easy removal and high molecular weight.

In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0 mol times relative to the diamine component.

Among the above-mentioned three polyamic acid ester synthesis methods, the high molecular weight polyamic acid ester is obtained, and therefore the synthesis method (1) or (2) is particularly preferable.

The polymer solution can be precipitated by injecting the polyamic acid ester solution obtained according to the above-described method into a poor solvent while thoroughly stirring. Precipitation is carried out several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained by normal temperature or heat drying. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<Polyimide>
The liquid crystal aligning agent of this embodiment contains the at least 1 sort (s) of polymer chosen from the polyimide precursor mentioned above and a polyimide. The polyimide contained in the liquid crystal aligning agent of this embodiment is a polyimide obtained by dehydrating and ring-closing the polyamic acid of the polyimide precursor described above. That is, the polyimide is a polyimide obtained by dehydrating and ring-closing the polyamic acid of the polyimide precursor synthesized using a diamine component containing the diamine compound having the specific structure of the formula (1) as an essential component. This polyimide is contained in the liquid crystal aligning agent of this embodiment, and is useful as a polymer for obtaining a liquid crystal aligning film.

In the polyimide contained in the liquid crystal aligning agent of this embodiment, the dehydration cyclization rate (imidization rate) of the amic acid group is not necessarily 100%, and can be arbitrarily adjusted according to the application and purpose. it can.

<Production method of polyimide>
In obtaining a polyimide using the above-mentioned polyamic acid, examples of the method for imidizing the polyamic acid include thermal imidization in which the polyamic acid solution is heated as it is, and catalytic imidation in which a catalyst is added to the polyamic acid solution.

At this time, it is desirable that the above-described polyamic acid is subjected to catalytic imidization that allows a reaction at a relatively low temperature.

The catalytic imidation of polyamic acid can be performed by adding a basic catalyst and an acid anhydride to a polyamic acid solution and stirring at -20 ° C to 250 ° C, preferably 0 ° C to 180 ° C. The amount of the basic catalyst is 0.5 mol times to 30 mol times, preferably 2 mol times to 20 mol times of the amic acid groups, and the amount of the acid anhydride is 1 mol times to 50 mol times of the amic acid groups, The amount is preferably 3 mole times to 30 mole times.

Examples of the basic catalyst used for the above-mentioned catalyst imidization include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like, and among them, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction.

Examples of the acid anhydride used for the catalyst imidization include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Of these, use of acetic anhydride is preferred because purification after completion of the reaction is facilitated.
The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

As mentioned above, although the component which can be contained in the liquid crystal aligning agent of this embodiment was demonstrated, the liquid crystal aligning agent of this embodiment prepared using them next is demonstrated.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of this embodiment is a coating liquid for forming a liquid crystal aligning film, and is a solution in which a resin component for forming a resin film is dissolved in an organic solvent. Here, the said resin component is a resin component containing the at least 1 sort (s) of polymer chosen from the polyimide precursor mentioned above and a polyimide. In that case, the content of the resin component is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 15% by mass, and still more preferably 3% by mass to 10% by mass.

In the present embodiment, all of the above resin components may be the above-described polymers, or other polymers may be mixed. In that case, the content of the polymer other than the above-mentioned polymer in the resin component is 0.5% by mass to 15% by mass, preferably 1% by mass to 10% by mass.

The organic solvent used in the liquid crystal aligning agent of the present embodiment is not particularly limited as long as it is an organic solvent that dissolves the resin component such as the above-described polymer. Specific examples are given below.

N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, Dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3 -Dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy- - and methyl-2-pentanone and the like. These may be used alone or in combination.

The liquid crystal aligning agent of this embodiment may contain components other than those described above. Examples thereof include solvents and compounds that improve the film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, and compounds that improve the adhesion between the liquid crystal aligning film and the substrate.

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

These poor solvents may be used alone or in combination. When the above solvent is used, it is preferably 5% by mass to 80% by mass, and more preferably 20% by mass to 60% by mass with respect to the total solvent contained in the liquid crystal aligning agent.

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
More specifically, for example, EFTOP (registered trademark) EF301, EF303, EF352 (manufactured by Tochem Products), MegaFac (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink, Inc.), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.) and the like.

The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent. Part.

Specific examples of the compound for improving the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds.
For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Propyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetra Glycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N Examples include ', N',-tetraglycidyl-4,4'-diaminodiphenylmethane.

When using the compound which improves adhesiveness with a board | substrate, it is preferable that the usage-amount is 0.1 to 30 mass parts with respect to 100 mass parts of the resin component contained in a liquid-crystal aligning agent. More preferably, it is 1 to 20 parts by mass. If the amount used is less than 0.1 part by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the liquid crystal orientation of the liquid crystal alignment film formed may be lowered.

In addition to the above, the liquid crystal aligning agent of the present embodiment has a dielectric or conductive property for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film as long as the effects of the present invention are not impaired. A substance, and further, a crosslinkable compound for the purpose of increasing the hardness and density of the liquid crystal alignment film may be added.
Next, a liquid crystal alignment film according to an embodiment of the present invention and a liquid crystal display element using the same will be described.

<Formation of liquid crystal alignment film>
The liquid crystal aligning agent of this embodiment described above contains at least one polymer selected from a polyimide precursor and a polyimide, synthesized using a diamine component containing the diamine compound of formula (1) as an essential component. To do. The liquid crystal aligning agent of this embodiment is preferably filtered before being applied to the substrate, then applied to the substrate, dried by prebaking, and then heated and fired to form a polymer film containing polyimide. be able to.

A coating method for applying the liquid crystal aligning agent of the present embodiment on a substrate is not particularly limited, but industrially, a method performed by screen printing, offset printing, flexographic printing, an inkjet method, or the like is common. . Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, or a spray method, and these may be used depending on the purpose. Even if the liquid crystal aligning agent of this embodiment is a case where the above application | coating method is used, applicability | paintability is favorable.

The step of drying by pre-baking after applying the liquid crystal aligning agent is not necessarily required, but when the time from application to heating and baking is not constant for each substrate, or when heating and baking is not performed immediately after application, It is preferable to include a drying step. The drying by this pre-bake should just evaporate the solvent to such an extent that a coating-film shape does not deform | transform by conveyance of a board | substrate.

The drying means is not particularly limited. As a specific example, a method of drying on a hot plate at 50 ° C. to 120 ° C., preferably 80 ° C. to 120 ° C. for 0.5 minutes to 30 minutes, preferably 1 minute to 5 minutes is preferable.

The substrate coated with the liquid crystal aligning agent can be baked at a temperature of 120 ° C. to 350 ° C. by a heating means such as a hot plate, a thermal circulation oven or an IR (infrared) oven. The firing temperature is preferably 140 ° C. to 300 ° C., more preferably 180 ° C. to 250 ° C. When polyamic acid or polyamic acid ester is contained in the liquid crystal aligning agent, the conversion rate to polyimide varies depending on the baking temperature, but the liquid crystal aligning agent of this embodiment does not necessarily need to be imidized 100%. And the baking time of the coating film of a liquid crystal aligning agent can be set to arbitrary time. If the baking time is too short, display failure may occur due to the influence of the residual solvent. Therefore, it is preferably 5 minutes to 60 minutes, more preferably 10 minutes to 40 minutes.

If the thickness of the polymer film containing polyimide obtained after firing is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element. If it is too thin, the reliability of the liquid crystal display element may be lowered. It is 200 nm, more preferably 50 nm to 100 nm. When the liquid crystal is horizontally or tilted, the polymer film after baking is preferably subjected to an alignment treatment such as rubbing by rubbing the film surface in a certain direction using a cloth.

The liquid crystal alignment film of the present embodiment formed as described above is a liquid crystal alignment film that is effective in reducing performance deterioration even when subjected to ultraviolet irradiation, and is subjected to a process of irradiating the pixel formation region with ultraviolet light. Provided is the liquid crystal display element of the present embodiment which is produced and suppresses the reduction in performance degradation.

Embodiment 2
The liquid crystal display element according to the second embodiment of the present invention uses a liquid crystal alignment film that is effective in reducing performance degradation even when irradiated with ultraviolet rays, as in the liquid crystal display element according to the first embodiment described above. Configured. And in the case of the liquid crystal display element which is 2nd Embodiment, the liquid crystal aligning film is a photo-alignment film which exhibits liquid crystal alignment control ability by the photo-alignment process by ultraviolet irradiation. Therefore, the liquid crystal display element according to the second embodiment of the present invention is created through a process of irradiating the formation region of the pixel with the liquid crystal alignment film with ultraviolet rays for the photo-alignment process, and suppresses the reduction in performance deterioration. Thus, a liquid crystal display element is obtained.

The liquid crystal display element of this embodiment can be a color liquid crystal display element of TN (Twisted Nematic) mode as an example, as in the first embodiment described above. Therefore, it can be set as the structure similar to the liquid crystal display element 1 of FIG. 1 which is 1st Embodiment mentioned above, and the overlapping description is abbreviate | omitted.

The liquid crystal alignment film of the liquid crystal display element of the second embodiment is preferably formed using a liquid crystal aligning agent, like the liquid crystal alignment film of the liquid crystal display element of the first embodiment. Then, the liquid crystal alignment film of the present embodiment is formed through a process of irradiating the pixel formation region with ultraviolet rays, and the liquid crystal display element of the present embodiment in which the reduction in performance deterioration is suppressed is described above. It is preferable to form using the liquid crystal aligning agent of 1st Embodiment.

And the liquid crystal aligning agent used by this embodiment is the liquid crystal aligning agent of 1st Embodiment mentioned above, Comprising: In the obtained liquid crystal aligning film, in order to implement | achieve the outstanding liquid crystal alignment control ability by a photo-alignment process, A polyimide precursor formed using a diamine component containing a diamine compound of the above formula (1) and a tetracarboxylic acid derivative in which Z ₁ is the formula (Z-1) in the above formulas (CB1) to (CB5) And at least one polymer selected from polyimides obtained by imidizing it. As a result, the liquid crystal alignment film of the present embodiment includes a diamine component containing the diamine compound of the above formula (1) and a tetracarboxylic acid in which Z ₁ is the formula (Z-1) in the above formulas (CB1) to (CB5). It comprises at least one polymer selected from a polyimide precursor formed using an acid derivative and a polyimide obtained by imidizing it.

The formation of the liquid crystal alignment film of this embodiment can be the same as that of the first embodiment described above. The method of photo-alignment treatment in the liquid crystal alignment film of the present embodiment is not particularly limited, but it is preferable to use polarized ultraviolet rays for obtaining uniform liquid crystal alignment. In this case, the method of irradiating polarized ultraviolet rays is not particularly limited. For example, it is possible to irradiate a substrate on which a polymer film containing a polymer such as polyimide is formed through a polarizing plate from a certain direction. Moreover, you may irradiate twice or more by changing the incident angle of polarized ultraviolet rays. Further, it is only necessary to obtain substantially polarized light, and non-polarized ultraviolet rays may be irradiated at an angle inclined from the normal line of the substrate.

As the wavelength of ultraviolet rays to be used, ultraviolet rays in the range of 100 nm to 400 nm can be generally used, but it is particularly preferable to select an optimum wavelength via a filter or the like depending on the type of polymer film to be used. . The irradiation time of ultraviolet rays is generally in the range of several seconds to several hours. In consideration of industrial productivity, it is preferable to select the necessary amount that realizes good liquid crystal alignment control ability depending on the type of liquid crystal alignment film to be used.

The liquid crystal display element of the second embodiment can be manufactured as follows. The liquid crystal display element of the present embodiment can have the same structure as the liquid crystal display element 1 of FIG. 1 which is the first embodiment described above, and the same reference numerals are used for the description of the common components. This will be described with reference to FIG.

First, the TFT substrate 2 having the structure described above is prepared. The TFT substrate 2 is manufactured, for example, by forming various electrodes including TFTs and pixel electrodes 6 on a substrate 5 made of a transparent glass substrate or the like according to a known method. Then, on the TFT substrate 2, the liquid crystal alignment film 12 of this embodiment subjected to the above-described photo-alignment processing is disposed.

Then, the CF substrate 3 having the above structure is prepared. The CF substrate 3 is formed, for example, by patterning the CF layer 7 having the colored layer 9 and the black matrix 10, the common electrode 11 and the like on the substrate 15 made of a transparent glass substrate or the like. And the liquid crystal aligning film 12 which performed the photo-alignment process mentioned above on the surface of the common electrode 11 is arrange | positioned. The black matrix is made of a metal material such as Ta (tantalum), Cr (chromium), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), Al (aluminum), or a black pigment such as carbon. Are dispersed or a resin material in which a plurality of colored layers having light transmittance are laminated.

Next, around the pixel formation region on the TFT substrate 2 where the pixel electrode 6 is formed, a sealing material is used, a method using a dispenser, a method of printing in a desired shape, and a photo coating after applying by a spin coating method. The sealing material 16 is formed in a frame shape according to a patterning method using a lithography method. As the sealing material, for example, a thermosetting type can be used.

Next, the TFT substrate 2 and the CF substrate 3 are preferably sandwiched with a spacer of 1 μm to 30 μm, more preferably 2 μm to 10 μm. The periphery is fixed with a sealing material 16. Next, liquid crystal is injected between the TFT substrate 2 and the CF substrate 3 and sealed to form the liquid crystal layer 4. The method for enclosing the liquid crystal is not particularly limited, and it is possible to use a vacuum method in which liquid crystal is injected after reducing the pressure of the pixel formation region surrounded by the sealing material 16 between the TFT substrate 2 and the CF substrate 3. . Moreover, the dropping method etc. which seal after sealing a liquid crystal demonstrated in 1st Example can be illustrated.
Then, the polarizing plate 17 is arrange | positioned to the surface of the TFT substrate 2 and the external side of the CF substrate 3 opposite to the liquid crystal layer 4, respectively, and the liquid crystal display element 1 is manufactured.

Therefore, in the manufacture of the liquid crystal display element of the present embodiment, the light irradiation step of irradiating ultraviolet rays is a step of performing an alignment treatment of the liquid crystal alignment film, and is a step of imparting liquid crystal alignment controllability to the liquid crystal alignment film. . The irradiation light has a wavelength characteristic suitable for the photo-alignment treatment of the liquid crystal alignment film, and as described above, the irradiation light can be ultraviolet light having a wavelength of 100 nm to 400 nm. And as above-mentioned, as for the irradiation amount of an ultraviolet-ray, it is preferable to select the quantity suitable for a photo-alignment process according to the kind of liquid crystal aligning film.

The liquid crystal display element of the present embodiment is configured using a liquid crystal alignment film including at least one polymer selected from a polyimide precursor having the structure described above and a polyimide obtained by imidizing the polyimide precursor, Due to the photo-alignment treatment, the deterioration of the performance is suppressed even when the pixel formation region is irradiated with ultraviolet rays. Therefore, the liquid crystal display element according to the present embodiment is a performance by ultraviolet irradiation, which has been a problem in the past, even when the liquid crystal display element is formed through a process of irradiating the pixel formation region with ultraviolet rays for photo-alignment processing. Deterioration can be suppressed. That is, according to the present embodiment, it is possible to provide a liquid crystal display element that is manufactured by using a light irradiation process that irradiates ultraviolet rays, and in which deterioration of display quality is suppressed.

In the liquid crystal display element 1 of the present embodiment, a photo-curing seal material such as a visible light curing type and an ultraviolet curing type can be used for forming the sealing material 16. As the visible light curable sealing material, for example, a photocurable resin that is cured by irradiation with visible light energy such as acrylic resin, methacrylic resin, epoxy resin, and silicone resin can be used. Further, as the ultraviolet curable sealing material, the same materials as those described in the first embodiment can be used.

Even if the sealing material is a photo-curing type, the liquid crystal display element of this embodiment is configured using a liquid crystal alignment film including the polyimide film having the above-described structure. For example, when the sealing material 16 is cured, In the formation region, deterioration of performance is suppressed even when irradiated with visible light or ultraviolet light. Therefore, the liquid crystal display element of this embodiment suppresses performance degradation due to visible light irradiation even when it is formed through a process of irradiating a pixel formation region with visible light or ultraviolet light after a photo-alignment process. be able to.

Embodiment 3
The liquid crystal display element according to the third embodiment of the present invention is a PSA (Polymer Sustained Alignment) type liquid crystal display element. A PSA-type liquid crystal display element is configured using a vertical alignment type liquid crystal alignment film as a liquid crystal alignment film.

Therefore, the liquid crystal alignment film of the liquid crystal display element of the third embodiment is preferably formed using a liquid crystal aligning agent, like the liquid crystal alignment film of the liquid crystal display element of the first embodiment. Then, the liquid crystal alignment film of the present embodiment is formed through a process of irradiating the pixel formation region with ultraviolet rays, and the liquid crystal display element of the present embodiment in which the reduction in performance deterioration is suppressed is described above. It is preferable to form using the liquid crystal aligning agent of 1st Embodiment. In particular, in the obtained liquid crystal alignment film, at least one layer selected from a polyimide precursor having a structure suitable for vertical alignment and a polyimide obtained by imidizing the polyimide precursor so that vertical alignment of liquid crystals can be realized. It is preferable to use the liquid crystal aligning agent of the first embodiment including a coalescence.

About the manufacturing method of the liquid crystal display element which is 3rd Embodiment, as mentioned above, the liquid crystal aligning agent of 1st Embodiment containing polymers, such as a polyimide precursor of a structure suitable for vertical alignment, is used for a board | substrate. After forming the liquid crystal alignment film, a liquid crystal cell can be prepared and obtained according to a known method. As an example of manufacturing a liquid crystal cell, a method is generally employed in which a pair of substrates on which the above-described liquid crystal alignment film is formed is fixed with a sealing material with a spacer interposed therebetween, and liquid crystal is injected and sealed. In this case, the size of the spacer used is 1 μm to 30 μm, preferably 2 μm to 10 μm.

The substrate used for the PSA liquid crystal display element of the present embodiment is not particularly limited as long as it is a highly transparent substrate, but is preferably a substrate on which a transparent electrode for driving liquid crystal is formed. As a substrate that can be used for a PSA liquid crystal display element, a standard electrode pattern such as PVA or MVA or a projection pattern can be used. However, as an example of a PSA type liquid crystal display element, it is desirable even in a structure in which a line / slit electrode pattern of 1 μm to 10 μm is formed on one side substrate and no slit pattern or projection pattern is formed on the opposite substrate. The operation of the liquid crystal is possible, and the PSA liquid crystal display element of this structural example can simplify the manufacturing process and obtain high transmittance.

In addition, as a substrate used for the PSA liquid crystal display element of this embodiment, a TFT substrate on which TFTs and electrodes are arranged can be used. In this example, a PSA liquid crystal display element driven by TFT is provided. be able to.

When the PSA type liquid crystal display element of the present embodiment is a transmissive type, it is preferable to use a transparent substrate as described above. However, when the PSA type liquid crystal display element is a reflective type, if only one substrate is used, an opaque material such as a silicon wafer is used. A simple substrate can also be used. At that time, a material such as aluminum that reflects light may be used for the electrode formed on the substrate.

The method for injecting the liquid crystal is not particularly limited, and examples thereof include a vacuum method for injecting the liquid crystal after reducing the pressure inside the produced liquid crystal cell, and a dropping method for sealing after dropping the liquid crystal.

In a PSA liquid crystal display element, a liquid crystal to which a small amount (preferably, 0.2 wt% to 1 wt%) of a photopolymerizable compound is used as a liquid crystal to be used. After obtaining the liquid crystal cell in which the liquid crystal is sealed and the liquid crystal layer is formed, a voltage is applied between the electrodes of the both side substrates sandwiching the liquid crystal layer of the liquid crystal cell. Then, by irradiating ultraviolet rays while the voltage is applied, the polymerizable compound is polymerized and crosslinked in that state, and as a result, the response speed of the liquid crystal display element is increased. Here, the applied voltage is 5 V _pp to 30 V _pp , but preferably 5 V _pp to 20 V _pp . The irradiation amount of ultraviolet rays to be irradiated is 1 J to 60 J, but preferably 40 J or less, and the smaller the ultraviolet irradiation amount, the lowering of the reliability of the liquid crystal display element can be suppressed, and the ultraviolet irradiation time can be reduced. This increases the manufacturing tact and is suitable for improving productivity.

As described above, the PSA-type liquid crystal display element according to the third embodiment of the present invention reduces performance degradation even when it is irradiated with ultraviolet rays, like the liquid crystal display element according to the first embodiment described above. It is comprised using the liquid crystal aligning film effective for. In the case of the liquid crystal display element according to the third embodiment, the liquid crystal is obtained by adding a small amount of a photopolymerizable compound, and the photopolymerizable compound is irradiated with ultraviolet rays when the liquid crystal display element is manufactured. Thus, desired response characteristics in the liquid crystal are realized. Therefore, the liquid crystal display element according to the third embodiment of the present invention is produced through a process of irradiating the pixel formation region with ultraviolet rays in order to react the photopolymerizable compound in the liquid crystal, and the performance deterioration is reduced. The liquid crystal display element is suppressed.

Embodiment 4
The liquid crystal display element which is the 4th Embodiment of this invention is a liquid crystal display element of an ultraviolet irradiation system. In the liquid crystal display element of the ultraviolet irradiation method, a liquid crystal alignment agent is applied on two substrates to form a liquid crystal alignment film, and the two substrates are arranged so that the liquid crystal alignment films face each other. This is a vertical alignment (VA) mode liquid crystal display element manufactured by sandwiching a liquid crystal layer between substrates and irradiating ultraviolet rays while applying an electric field to the liquid crystal layer. An ultraviolet irradiation type liquid crystal display element is configured using a vertical alignment type liquid crystal alignment film as a liquid crystal alignment film.

Therefore, the liquid crystal alignment film of the liquid crystal display element of the fourth embodiment is preferably formed using a liquid crystal aligning agent, like the liquid crystal alignment film of the liquid crystal display element of the first embodiment. Then, the liquid crystal alignment film of the present embodiment is formed through a process of irradiating the pixel formation region with ultraviolet rays, and the liquid crystal display element of the present embodiment in which the reduction in performance deterioration is suppressed is described above. It is preferable to form using the liquid crystal aligning agent of 1st Embodiment. In particular, in the obtained liquid crystal alignment film, at least one layer selected from a polyimide precursor having a structure suitable for vertical alignment and a polyimide obtained by imidizing the polyimide precursor so that vertical alignment of liquid crystals can be realized. It is preferable to use the liquid crystal aligning agent of the first embodiment including a coalescence.

Furthermore, unlike the PSA method described above, a polyimide precursor having a structure suitable for the ultraviolet irradiation method and a polyimide obtained by imidizing it are selected so that it is not necessary to add a photopolymerizable compound to the liquid crystal. It is particularly preferable that the liquid crystal aligning agent according to the first embodiment including at least one polymer is used. By doing so, the response characteristics of the liquid crystal can be easily improved.

About the manufacturing method of the liquid crystal display element which is 4th Embodiment, as mentioned above, the liquid crystal alignment of 1st Embodiment containing polymers, such as a polyimide precursor of a structure suitable for a vertical alignment and a suitable ultraviolet irradiation system, as mentioned above. After forming a liquid crystal alignment film on a substrate using an agent, a liquid crystal cell can be produced according to a known method. As an example of liquid crystal cell production, prepare a pair of substrates on which the above-mentioned liquid crystal alignment film is formed, spray spacers on the liquid crystal alignment layer of one substrate, and make the liquid crystal alignment layer surface inside. Examples include a method in which one substrate is bonded and liquid crystal is injected under reduced pressure, or a method in which liquid crystal is dropped on the surface of the liquid crystal alignment layer on which spacers are dispersed and then the substrate is bonded and sealed. In this case, the size of the spacer used is 1 μm to 30 μm, preferably 2 μm to 10 μm.

The substrate used for manufacturing the liquid crystal display element of the present embodiment is not particularly limited as long as it is a highly transparent substrate, but is preferably a substrate on which a transparent electrode for driving liquid crystal is formed. As a substrate that can be used for an ultraviolet irradiation type liquid crystal display element, a standard electrode pattern such as PVA or MVA or a projection pattern can also be used. However, as an example of an ultraviolet irradiation type liquid crystal display element, a structure in which a line / slit electrode pattern of 1 μm to 10 μm is formed on one substrate and a slit pattern or a protrusion pattern is not formed on the opposite substrate is desirable. The operation of the liquid crystal can be performed, and the ultraviolet ray irradiation type liquid crystal display element of this structural example can simplify the manufacturing process and obtain a high transmittance.

In addition, as a substrate used for the ultraviolet irradiation type liquid crystal display element of this embodiment, a TFT substrate on which TFTs and electrodes are arranged can be used. In this example, an ultraviolet irradiation type liquid crystal display element driven by a TFT is used. Can be provided.

When the ultraviolet irradiation type liquid crystal display element of the present embodiment is a transmissive type, it is preferable to use a transparent substrate as described above. However, in the case of a reflective type, if only one side of the substrate is used, a silicon wafer or the like can be used. An opaque substrate can also be used. At that time, a material such as aluminum that reflects light may be used for the electrode formed on the substrate.

The liquid crystal used in the liquid crystal display element of this embodiment may be a liquid crystal to which no photopolymerizable compound is added, or a liquid crystal to which a photopolymerizable compound is added. The liquid crystal display element of this embodiment can increase the response speed regardless of which liquid crystal is used.

The step of irradiating ultraviolet rays while applying an electric field to the liquid crystal layer is, for example, a method in which an electric field is applied to the liquid crystal layer by applying a voltage between electrodes installed on the substrate, and the ultraviolet rays are irradiated while maintaining the electric field. Is mentioned. Here, the voltage applied between the electrodes is, for example, 55 V _pp to 30 V _pp , and preferably 5 V _pp to 20 V _pp . The irradiation amount of ultraviolet rays to be irradiated is 1 J to 60 J, but preferably 40 J or less, and the smaller the ultraviolet irradiation amount, the lowering of the reliability of the liquid crystal display element can be suppressed, and the ultraviolet irradiation time can be reduced. This increases the manufacturing tact and is suitable for improving productivity.

As described above, the ultraviolet irradiation type liquid crystal display element according to the fourth embodiment of the present invention reduces the performance deterioration even when the ultraviolet irradiation is performed, similarly to the liquid crystal display element according to the first embodiment described above. It is configured using a liquid crystal alignment film effective for the above. And in the case of the liquid crystal display element which is 4th Embodiment, the desired response characteristic in a liquid crystal is implement | achieved by irradiating the formation area of a pixel in which the liquid crystal layer was formed at the time of the manufacture. Therefore, the liquid crystal display element according to the fourth embodiment of the present invention is produced through a process of irradiating the pixel formation region in which the liquid crystal layer is formed, with ultraviolet rays, and the reduction in performance deterioration is suppressed. It becomes an element.

The following examples further illustrate the present invention. The present invention is not construed as being limited to these.
Main compounds, abbreviations and structures used in Examples and Comparative Examples are as follows.
<Structural formula>

<Tetracarboxylic acid derivative>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

<Diamine compound>
DDM: 4,4′-diaminodiphenylmethane terphenyl: 4,4′-diaminoparaterphenyl ADA: bis (paraaminophenyl) -9,10-anthracene p-PDA: 1,4-phenylenediamine <solvent>
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve

Next, the method of molecular weight measurement performed in the present example and the comparative example will be described.
[Molecular weight measurement]
The molecular weight of the polyimide in the synthesis example was measured as follows using a room temperature gel permeation chromatography (GPC) apparatus (SSC-7200) manufactured by Senshu Science Co., Ltd. and a column (KD-803, KD-805) manufactured by Shodex.
Column temperature: 50 ° C
Eluent: N, N′-dimethylformamide (as additives, lithium bromide-hydrate (LiBr · H ₂ O) is 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, Tetrahydrofuran (THF) 10ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: about 9000000, 150,000, 100,000, 30000) manufactured by Tosoh Corporation and polyethylene glycol (molecular weight: about 12000, 4000, 1000) manufactured by Polymer Laboratories .

<Example 1>
CBDA (7.4 g, 38 mmol) and ADA (14.4 g, 40 mmol) were mixed in NMP (87.5 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. NMP (182.3g) and BC (72.9g) were added to this polyamic acid solution, diluted to 6% by mass, and stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (A1). The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (A1) was 8000, and the weight average molecular weight was 19,500.

<Example 2>
CBDA (4.5 g, 23 mmol), ADA (4.3 g, 12 mmol), p-PDA (1.3 g, 12 mmol) were mixed in NMP (90.8 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. Obtained. NMP (33.6 g) and BC (33.6 g) were added to this polyamic acid solution, diluted to 6% by mass, and stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (A2). The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (A2) was 9600, and the weight average molecular weight was 21,000.

<Comparative Example 1>
CBDA (7.5 g, 38.4 mmol) and DDM (7.9 g, 40 mmol) were mixed in NMP (87.6 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. NMP (103.1 g) and BC (51.5 g) were added to this polyamic acid solution, diluted to 6% by mass, and stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (B1). The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (B1) was 9800, and the weight average molecular weight was 19000.

<Comparative example 2>
CBDA (7.5 g, 38 mmol) and terphenyl (10.4 g, 40 mmol) were mixed in NMP (160.8 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. NMP (59.6 g) and BC (59.6 g) were added to this polyamic acid solution, diluted to 6% by mass, and stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (B2). The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (B2) was 8000, and the weight average molecular weight was 18000.

<Comparative Example 3>
CBDA (5.5 g, 29 mmol) and p-PDA (3.2 g, 30 mmol) were mixed in NMP (101.6 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. NMP (7.4 g) and BC (29.4 g) were added to this polyamic acid solution, diluted to 6% by mass, and stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (B3). The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (B3) was 10,000, and the weight average molecular weight was 22,000.

<Example 3>
[Evaluation of light resistance by measuring voltage holding ratio (VHR)]
The liquid crystal aligning agent (A1) obtained in Example 1 was filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried on an 80 ° C. hot plate for 5 minutes, and then at 250 ° C. A film having a thickness of 100 nm was obtained by baking for 20 minutes. After rubbing this polyimide film with a rayon cloth (roll diameter 120 mm, rotation speed 1000 rpm, moving speed 30 mm / sec, pushing amount 0.2 mm), ultrasonic irradiation was performed in pure water for 1 minute, and 80 ° C. for 10 minutes. Dried. Two substrates with such a liquid crystal alignment film are prepared, a spacer of 6 μm is installed on the surface of the liquid crystal alignment film of one substrate, and then combined so that the rubbing directions of the two substrates are orthogonal to each other. The periphery was sealed and the empty cell having a cell gap of 6 μm was produced. Liquid crystal (MLC-2003 (C080), manufactured by Merck Japan Co., Ltd.) was vacuum-injected into this cell at room temperature, and the inlet was sealed to obtain a liquid crystal cell in which the liquid crystal was twisted by 90 degrees.

And VHR was evaluated.
VHR is evaluated by applying a voltage of 4V to the obtained liquid crystal cell at a temperature of 23 ° C. for 60 μs, measuring the voltage after 16.67 ms, and calculating how much the voltage can be held as the voltage holding ratio. did. The same measurement was performed at a temperature of 90 ° C. The voltage holding ratio was measured using a voltage holding ratio measuring device VHR-1 manufactured by Toyo Technica. The evaluation results are shown in Table 1.
Next, the liquid crystal cell was irradiated with 1 J of 365 nm ultraviolet light, and VHR after the ultraviolet irradiation was similarly evaluated. The evaluation results are shown in Table 1.

Using the liquid crystal aligning agent (B1) obtained in Comparative Example 1 and the liquid crystal aligning agent (B2) obtained in Comparative Example 2, a liquid crystal cell was produced in the same manner as in the case of using the liquid crystal aligning agent (A1). The VHR before and after UV irradiation was evaluated by the same method. The evaluation results are summarized in Table 1.

<Example 4>
[Evaluation of photo-alignment]
The liquid crystal aligning agent (A1) obtained in Example 1 was filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried on an 80 ° C. hot plate for 5 minutes, and then 220 ° C. Was baked for 30 minutes in a hot air circulation oven to form a coating film having a thickness of 100 nm. The coating surface was irradiated with 254 nm ultraviolet light through a polarizing plate at 500 mJ / cm ² to obtain a substrate with a liquid crystal alignment film.

In order to evaluate the electrical characteristics of the liquid crystal cell, two substrates with the above-mentioned liquid crystal alignment film were prepared, and 4 μm spacers were dispersed on the surface of the one liquid crystal alignment film. A sealing material was printed thereon, and another substrate was bonded so that the liquid crystal alignment film faces each other and the photo-alignment directions were orthogonal to each other, and then the sealing material was cured to produce an empty cell. Liquid crystal MLC-2003 ((C080), manufactured by Merck Japan Co., Ltd.) was vacuum-injected into this empty cell by vacuum injection at room temperature, the injection port was sealed, and the liquid crystal was subjected to photo-alignment treatment in which the liquid crystal was twisted 90 degrees. I got a cell. When this liquid crystal cell was heat-treated at 105 ° C. for 10 minutes and then slowly cooled to room temperature, the cell was observed. The orientation was good. The evaluation results are summarized in Table 2.

Using the liquid crystal aligning agent (A2) obtained in Example 2, a liquid crystal cell was produced in the same manner as in the case of using the liquid crystal aligning agent (A1) described above, and the alignment was evaluated in the same manner. . The evaluation results are summarized in Table 2.

Using the liquid crystal aligning agent (B3) obtained in Comparative Example 3, a liquid crystal cell was produced in the same manner as in the case of using the liquid crystal aligning agent (A1) described above, and the alignment was evaluated in the same manner. . The evaluation results are summarized in Table 2.

<Example 5>
[Measurement of residual DC]
Using each of the liquid crystal cells produced in Example 4, residual DC was measured by a dielectric absorption method using a 6254 type liquid crystal physical property evaluation apparatus manufactured by Toyo Technica. The measurement is performed in an environment of 60 ° C., a DC voltage of 10 V is applied to the cell for 30 minutes and then discharged for 1 second, and after 20 minutes the residual DC amount is 500 mV or less “good”, 500 mV or more Was defined as “bad”. The evaluation results are summarized in Table 2. Among the liquid crystal cells manufactured in Example 4, the evaluation results were obtained in the liquid crystal cells manufactured using the liquid crystal aligning agents (A1, A2) of Example 1 and Example 2. Was “good”.

From the above, it was found that the liquid crystal display element of this example had a good charge retention even when irradiated with ultraviolet rays, and the performance deterioration due to ultraviolet irradiation was reduced.
In addition, it was found that the liquid crystal display element of this example achieved good alignment of the liquid crystal by photo-alignment treatment, had excellent residual DC characteristics, and reduced performance deterioration due to ultraviolet irradiation.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 TFT substrate 3 CF substrate 4

Liquid crystal layers

5 and 15 Substrate 6 Pixel electrode 7 CF layer 8 Protective layer 9 Colored layer 10 Black matrix 11 Common electrode 12 Liquid crystal alignment film 16 Sealing material 17 Polarizing plate

The liquid crystal display element of the present invention is a liquid crystal display element that is produced through a process of irradiating a pixel formation region with ultraviolet rays, and the reduction in performance deterioration is suppressed. Accordingly, both excellent display characteristics and productivity can be achieved. Therefore, it can be suitably used for manufacturing a liquid crystal display element for a portable information terminal such as a large-sized liquid crystal TV or a smartphone displaying a high-definition image.

Claims

In a pixel formation region, a liquid crystal alignment film including at least one polymer selected from a polyimide precursor formed using a compound represented by the following formula (1) and a polyimide obtained by imidizing the polyimide precursor is provided. ,
A liquid crystal display element, wherein the pixel formation region is configured by irradiating with ultraviolet rays.
The liquid crystal alignment film was formed using a compound represented by the above formula (1) and a compound represented by the following formula (AM) (excluding a compound represented by the above formula (1)). The liquid crystal display element according to claim 1, comprising at least one polymer selected from a polyimide precursor and a polyimide obtained by imidization thereof.

(In Formula (AM), Y 1 is a divalent organic group, and two or more types may be present. In Formula (AM), R 1 and R 2 are a hydrogen atom or a monovalent group. Represents an organic group.)
The liquid crystal alignment film includes at least one selected from a polyimide precursor formed using at least one of compounds represented by the following formulas (CB1) to (CB5) and a polyimide obtained by imidizing the polyimide precursor. The liquid crystal display element according to claim 1, comprising a polymer.

(In the formulas (CB1) to (CB5), Z 1 is a tetravalent organic group having 4 to 13 carbon atoms and contains a non-aromatic cyclic hydrocarbon group having 4 to 6 carbon atoms. Formula (CB4) In (CB5), R 3 represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms.)
A method for manufacturing a liquid crystal display element having a liquid crystal layer and a liquid crystal alignment film in a pixel formation region,
The liquid crystal alignment film including at least one polymer selected from a polyimide precursor formed using a compound represented by the following formula (1) and a polyimide obtained by imidizing the polyimide in a formation region of the pixel: A liquid crystal alignment film forming step to be formed;
A method of manufacturing a liquid crystal display element, comprising: a light irradiation step of irradiating the formation region of the pixel with ultraviolet rays after the liquid crystal alignment film formation step.
The liquid crystal alignment film was formed using a compound represented by the above formula (1) and a compound represented by the following formula (AM) (excluding a compound represented by the above formula (1)). The method for producing a liquid crystal display element according to claim 4, comprising at least one polymer selected from a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor.

(In Formula (AM), Y 1 is a divalent organic group, and two or more types may be present. In Formula (AM), R 1 and R 2 are a hydrogen atom or a monovalent group. Represents an organic group.)
The liquid crystal alignment film includes at least one selected from a polyimide precursor formed using at least one of compounds represented by the following formulas (CB1) to (CB5) and a polyimide obtained by imidizing the polyimide precursor. The method for producing a liquid crystal display element according to claim 4, comprising a polymer.

(In the formulas (CB1) to (CB5), Z 1 is a tetravalent organic group having 4 to 13 carbon atoms and contains a non-aromatic cyclic hydrocarbon group having 4 to 6 carbon atoms. Formula (CB4) In (CB5), R 3 represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms.)
After the liquid crystal alignment film forming step, a seal forming step of forming a sealing material around the pixel forming region,
7. The method of manufacturing a liquid crystal display element according to claim 4, wherein the light irradiation step is a step of curing the sealing material in the seal forming step.
7. The method for manufacturing a liquid crystal display element according to claim 4, wherein the light irradiation step is a step of aligning the liquid crystal alignment film.
After the liquid crystal alignment film formation step, the step of forming the liquid crystal layer in the pixel formation region,
7. The liquid crystal display element according to claim 4, wherein the light irradiation step is a step of irradiating the formation region of the pixel with ultraviolet light while driving the liquid crystal of the liquid crystal layer. Production method.
The liquid crystal layer includes a liquid crystal and a photopolymerizable compound,
7. The liquid crystal display element according to claim 4, wherein the light irradiation step is a step of polymerizing the photopolymerizable compound in the liquid crystal layer in the pixel formation region. Production method.
After the liquid crystal alignment film formation step, the step of forming the liquid crystal layer in the pixel formation region,
The method of manufacturing a liquid crystal display element according to claim 10, wherein the light irradiation step is a step of irradiating the formation region of the pixel with ultraviolet rays while driving the liquid crystal of the liquid crystal layer.