CN111690321B

CN111690321B - Varnish for photo-alignment film and liquid crystal display device

Info

Publication number: CN111690321B
Application number: CN202010173215.9A
Authority: CN
Inventors: 国松登; 富冈安; 园田英博
Original assignee: Japan Display Inc
Current assignee: Japan Display Inc
Priority date: 2019-03-15
Filing date: 2020-03-12
Publication date: 2022-02-08
Anticipated expiration: 2040-03-12
Also published as: JP2020149001A; CN111690321A

Abstract

The present invention relates to a varnish for a photo-alignment film and a liquid crystal display device. According to an embodiment, the varnish for a photo-alignment film contains, in an organic solvent: a1 st polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 2 nd polyamic acid compound as a polyamic acid, which has a polarity higher than that of the 1 st polyamic acid compound. The tetracarboxylic acid ester residue has a cyclobutane skeleton. The diamine compound residue contains a1 st diamine compound residue comprising an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group.

Description

Varnish for photo-alignment film and liquid crystal display device

RELATED APPLICATIONS

The present application claims the benefit of priority based on japanese application laid-open at 3/15 of 2019, application No. 2019-048592, the entire base application being incorporated herein.

Technical Field

Embodiments of the present invention relate to a varnish for a photo-alignment film and a liquid crystal display device.

Background

The liquid crystal display device has 2 substrates (1 st substrate and 2 nd substrate) arranged to face each other. The 1 st substrate has a1 st region and a 2 nd region, and the 2 nd substrate is opposed to the 1 st region of the 1 st substrate but is not opposed to the 2 nd region of the 1 st substrate. That is, the 2 nd region of the 1 st substrate protrudes outward from the end edge of the 2 nd substrate. Pixel electrodes, TFTs, and the like are provided in the 1 st region of the 1 st substrate, and color filters, light-shielding films, and the like are provided on the 2 nd substrate. In the 2 nd region of the 1 st substrate, an external circuit and the like are provided.

The 1 st substrate and the 2 nd substrate are bonded to each other at the peripheral edge of the 1 st region of the 1 st substrate and the peripheral edge of the 2 nd substrate by a frame-shaped sealing portion so that a constant cell gap (cell gap) is defined therebetween, and liquid crystal is sealed inside the sealing portion. The frame-shaped sealing portion is covered with a light-shielding film provided on the 2 nd substrate, the frame-shaped sealing portion and the light-shielding film define a non-display region, and the non-display region defines an image display region inside the non-display region. An alignment film for aligning liquid crystal molecules of the liquid crystal layer is provided on the liquid crystal side of each substrate.

The alignment film is generally formed by: a precursor organic compound solution (varnish for alignment film) dissolved in an organic solvent is applied to each substrate, and heated to convert the precursor organic compound solution into an organic film, thereby imparting an alignment controllability to the organic film. Conventionally, the peripheral edge of the alignment film is provided so as to terminate at the boundary between the image display region and the non-display region, and so as not to protrude into the non-display region.

As a method of imparting an alignment controllability to an organic film, photo-alignment treatment is employed in which an alignment controllability is imparted to an organic film in a non-contact manner. In the photo-alignment treatment, for example, polarized ultraviolet light in a 254nm to 365nm region is irradiated to the organic film, and molecules of the organic film are cut in a direction parallel to the polarization direction, thereby imparting uniaxial anisotropy to the organic film in a direction orthogonal to the polarization direction. The liquid crystal molecules are initially aligned by the alignment film to which uniaxial anisotropy has been imparted.

Recently, in liquid crystal display devices, it has been required to narrow the non-display region, that is, to narrow the frame, and therefore it has been difficult to provide the peripheral edge of each alignment film so as to terminate at the boundary between the image display region and the non-display region. As a result, the peripheral edge of each alignment film is gradually provided so as to protrude into the non-display region, and the frame-shaped sealing portion is gradually configured to bond the 1 st substrate and the 2 nd substrate via each alignment film (see, for example, japanese patent application laid-open No. 2018-146870).

Disclosure of Invention

However, the adhesion strength between the alignment film (photo-alignment film) formed by the photo-alignment treatment and the frame-shaped sealing portion may be insufficient. Therefore, if the adhesion strength between the photo-alignment film and the sealing portion is to be improved, the performance of initial alignment of the liquid crystal molecules (alignment controllability) may be reduced.

The invention provides a varnish for forming a photo-alignment film with improved bonding strength with a sealing part under the condition of not reducing the performance of initial alignment of liquid crystal molecules of a liquid crystal layer.

Another object of the present invention is to provide a liquid crystal display device including the photo-alignment film.

According to one aspect, there is provided a varnish for a photo-alignment film, comprising, in an organic solvent: a1 st polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 2 nd polyamic acid compound which is a polyamic acid having a polarity higher than that of the 1 st polyamic acid compound, wherein the tetracarboxylic acid ester residue has a cyclobutane skeleton, and the diamine compound residue contains a1 st diamine compound residue comprising an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group.

According to another aspect, there is provided a liquid crystal display device including: a1 st substrate, a 2 nd substrate disposed to face the 1 st substrate with a space therebetween, a frame-shaped sealing portion for bonding the 1 st substrate and the 2 nd substrate to each other, a liquid crystal layer located between the 1 st substrate and the 2 nd substrate and the sealing portion, and an alignment film located on the 1 st substrate and in contact with the liquid crystal layer and the sealing portion, wherein the alignment film includes an imide compound of the varnish for a photo-alignment film of the present invention.

Drawings

Fig. 1 is a schematic plan view of a liquid crystal display device according to an embodiment.

Fig. 2 is an enlarged schematic cross-sectional view of a part of the broken line ii-ii in fig. 1.

FIG. 3 is an enlarged schematic cross-sectional view of a part of the broken line iii-iii in FIG. 1.

Fig. 4 is a schematic view showing a structure of a photo-alignment film having a two-layer structure according to an embodiment.

Fig. 5 is a view showing an inspection pattern in a sintering test.

Detailed Description

Hereinafter, some embodiments will be described with reference to the drawings. In the drawings, the width, thickness, shape, and the like of each part are schematically shown in comparison with the actual form in order to make the description more clear, but the drawings are merely examples and do not limit the explanation of the present invention. In the present specification and the drawings, the same reference numerals are given to components that exhibit the same or similar functions as those of the components described in the previous drawings, and overlapping detailed description may be omitted as appropriate.

< liquid Crystal display device >

The liquid crystal display device DSP according to the embodiment will be described with reference to fig. 1 to 3. Fig. 1 is a schematic plan view of a liquid crystal display device DSP, fig. 2 is a schematic enlarged cross-sectional view of a portion broken along the line ii-ii in fig. 1, and fig. 3 is a schematic enlarged cross-sectional view of a portion broken along the line iii-iii in fig. 1.

In the present embodiment, a direction parallel to a short side of the liquid crystal display device DSP is defined as a1 st direction X, a direction parallel to a long side of the liquid crystal display device DSP is defined as a 2 nd direction Y, and a direction perpendicular to the 1 st direction X and the 2 nd direction Y is defined as a 3 rd direction Z. The 1 st direction X and the 2 nd direction Y are orthogonal to each other in the present embodiment, but may intersect at an angle other than 90 degrees.

In the present embodiment, the positive direction in the 3 rd direction Z is defined as up or up, and the negative direction in the 3 rd direction Z is defined as down or down. The liquid crystal display device DSP viewed from above is referred to as a plan view. The liquid crystal display device DSP in a top view is shown in a top view (fig. 1).

As shown in fig. 1, the liquid crystal display device DSP includes a display panel PNL, a driver IC chip 1, and a Flexible Printed Circuit (FPC) substrate 2. The display panel PNL is a liquid crystal display panel, and includes a1 st substrate SUB1, a 2 nd substrate SUB2, a liquid crystal layer LC described later, a seal portion SE formed in a frame shape, a non-display region NDA, and an image display region DA.

The 1 st substrate SUB1 and the 2 nd substrate SUB2 are arranged to face each other with a space therebetween (fig. 2). The 1 st substrate SUB1 has a region facing the 2 nd substrate SUB2 and a mounting portion MT projecting in the 2 nd direction Y with respect to the 2 nd substrate SUB 2. In other words, the mounting portion MT of the 1 st substrate SUB1 extends outward from the end edge of the 2 nd substrate SUB 2.

The driver IC chip 1 is mounted on the front half portion of the mounting portion MT in the 2 nd direction Y. The driver IC chip 1 may include a display driver that outputs a signal necessary for image display in a display mode for displaying an image, and a touch controller that controls a touch sensing mode for detecting proximity or contact of an object to the liquid crystal display device DSP.

The FPC board 2 is mounted on the rear half of the mounting portion MT in the 2 nd direction Y. A circuit board (not shown) is electrically connected to the FPC board 2 in the 2 nd direction Y. The circuit board transmits a driving signal to the 1 st substrate SUB1 through the FPC substrate 2.

The non-display area NDA defines an image display area DA in which an image is displayed, on the inner side thereof. The image display area DA includes a plurality of pixels PX arranged in a matrix along the 1 st direction X and the 2 nd direction Y.

The 1 st substrate SUB1 and the 2 nd substrate SUB2 are bonded to each other at a sealing portion SE formed in a frame shape at the peripheral edge portion of the 1 st substrate SUB1 and the peripheral edge portion of the 2 nd substrate SUB2 excluding the mounting portion MT. The frame-shaped seal portion SE defines a constant cell gap between the 1 st substrate SUB1 and the 2 nd substrate SUB 2. Liquid crystal is sealed between the 1 st substrate SUB1 and the 2 nd substrate SUB2 and inside the seal portion SE, and a liquid crystal layer LC (fig. 3) described later is formed.

The display panel PNL of the present embodiment may be any of a transmissive type having a transmissive display function of selectively transmitting light from the back surface side of the 1 st substrate SUB1 to display an image, a reflective type having a reflective display function of selectively reflecting light from the front surface side of the 2 nd substrate SUB2 to display an image, and a transflective type having a transmissive display function and a reflective display function.

Note that, although the detailed configuration of the display panel PNL is omitted here, the display panel PNL may have any configuration corresponding to a display mode using a lateral electric field along the main surface of the substrate, a display mode using a vertical electric field along the normal to the main surface of the substrate, a display mode using an oblique electric field oblique in the oblique direction with respect to the main surface of the substrate, and a display mode using the lateral electric field, the vertical electric field, and the oblique electric field in combination as appropriate. The substrate main surface herein refers to a surface parallel to an X-Y plane defined by the 1 st direction X and the 2 nd direction Y.

As shown in fig. 2, the 1 st substrate SUB1 includes a1 st insulating substrate 10, 1 st and 2 nd

insulating films

11 and 12, a common electrode CE, and a pixel electrode PE. The example shown in fig. 2 corresponds to an example in which an FFS (Fringe Field Switching) mode, which is one of display modes using a horizontal electric Field, is applied.

The 1 st insulating substrate 10 is a light-transmitting substrate such as a glass substrate or a flexible resin substrate. An optical element OD1 including a polarizing plate PL1 was bonded to the lower surface of the 1 st insulating substrate 10. The optical element OD1 may be provided with a retardation plate, a scattering layer, an antireflection layer, and the like as necessary. Below the optical element OD1, a lighting device BL is provided.

The 1 st insulating film 11 is disposed on the 1 st insulating substrate 10. On the 1 st insulating film 11 disposed in the non-display region NDA, an uneven portion 111 and a slit 112 are formed (fig. 3). The slit 112 penetrates the 1 st insulating film 11 to expose the surface of the 1 st insulating substrate 10. The 1 st insulating film 11 is an inorganic insulating film made of an insulating inorganic material such as silicon oxide, silicon nitride, or silicon oxynitride, and may have a single-layer structure or a multi-layer structure.

The common electrode CE is disposed over the 1 st insulating film 11. The common electrode CE is a transparent electrode formed of a transparent conductive material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO).

The 2 nd insulating film 12 is disposed over the common electrode CE. In addition, the 2 nd insulating film 12 is disposed along the surface of the concave and convex portion 111 of the 1 st insulating film 11 in the non-display region NDA (fig. 3). The 2 nd insulating film 12 is an inorganic insulating film made of an insulating inorganic material such as silicon oxide, silicon nitride, or silicon oxynitride, and may have a single-layer structure or a multi-layer structure, as in the 1 st insulating film 11.

The pixel electrode PE is disposed on the 2 nd insulating film 12. The pixel electrode PE is a transparent electrode formed of a transparent conductive material such as ITO or IZO. A slit SLA is formed on the pixel electrode PE. The slit SLA penetrates the pixel electrode PE to expose the 2 nd insulating film 12.

On the pixel electrode PE and the 2 nd insulating film 12, a1 st alignment film AL1 is provided so as to cover them. The 1 st alignment film AL1 provided in the non-display area NDA covers the surface of the 1 st insulating substrate 10 exposed through the slit 112 (fig. 3). The detailed structure of the 1 st alignment film AL1 will be described in detail later.

The 2 nd substrate SUB2 includes a 2 nd insulating substrate 20, a color filter CF, a light-shielding film BM, and a protective (overcoat) layer OC.

The 2 nd insulating substrate 20 is a light-transmitting substrate such as a glass substrate or a flexible resin substrate, as in the 1 st insulating substrate 10. An optical element OD2 including a polarizing plate PL2 was bonded to the 2 nd insulating substrate 20. The optical element OD2 may be provided with a retardation plate, a scattering layer, an antireflection layer, and the like as necessary.

The color filter CF is located on the 2 nd insulating substrate 20 on the side opposite to the 1 st substrate SUB 1. The color filter CF includes a green color filter segment CFG adjacent to the red and blue color filter segments CFR, CFB.

The light-shielding film BM is disposed between the color filter segments to prevent color mixing of the color filter segments. The light shielding film BM is also disposed on the surface of the 2 nd insulating substrate 20 on the side opposite to the 1 st substrate SUB1 in the non-display region NDA (fig. 3).

The overcoat layer OC covers the color filter CF in the image display area DA and the light shielding film BM in the non-display area NDA (fig. 3). A concave-convex portion OC1 is formed on the overcoat layer OC in the non-display area NDA. The protective layer OC is formed of a transparent resin.

On the side of the protective layer OC facing the 1 st substrate SUB1, a protrusion PJ (fig. 3) that defines the edge of the 2 nd alignment film AL2, a 2 nd alignment film AL2, and a spacer SP (fig. 3) are provided. The projection PJ is provided on the distal end side in the non-display area NDA and is formed of a resin material.

The 2 nd alignment film AL2 covers the overcoat layer OC in the image display region DA, and covers the concave and convex portion OC1 of the overcoat layer OC and the end portion of the spacer SP on the 2 nd insulating substrate 20 side in the non-display region NDA. The end of the 2 nd alignment film AL2 is in contact with the projection PJ. The detailed constitution of the 2 nd alignment film AL2 will be described later.

The spacer SP maintains a cell gap between the 1 st substrate SUB1 and the 2 nd substrate SUB 2. The top end of the spacer SP is not in contact with the 1 st alignment film AL 1. The spacer SP is formed of a resin material.

The seal portion SE is formed in a frame shape in the non-display region NDA (fig. 1), and sandwiches the liquid crystal layer LC together with the 1 st alignment film AL1 and the 2 nd alignment film AL 2. The seal portion SE is bonded to the 1 st alignment film AL1 and the 2 nd alignment film AL2, and connects the 1 st substrate SUB1 and the 2 nd substrate SUB2 via the 1 st and 2 nd alignment films AL1 and AL 2.

The seal portion SE includes, for example, an epoxy resin having no acrylate skeleton and a resin having an acrylate skeleton. For example, an epoxy resin having no acrylate skeleton functions as a thermosetting resin, and a resin having an acrylate skeleton functions as a photocurable resin.

The epoxy resin not having an acrylate skeleton is not particularly limited, and may be appropriately selected from a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, an alicyclic epoxy resin, and the like. For example, the epoxy resin is bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol type epoxy resin, propylene oxide-added bisphenol a type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, thioether type epoxy resin, ether type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, phenol Novolac type epoxy resin, o-cresol Novolac type epoxy resin, dicyclopentadiene Novolac type epoxy resin, biphenyl Novolac type epoxy resin, glycidyl amine type epoxy resin, alkyl polyhydric alcohol type epoxy resin, rubber-modified epoxy resin, glycidyl ester compound, bisphenol a type epoxy resin, or other epoxy resin. These epoxy resins having no acrylate skeleton may be used alone, or 2 or more kinds thereof may be used in combination.

The resin having an acrylate skeleton is not particularly limited, and may be appropriately selected from polyester (meth) acrylate resin, epoxy (meth) acrylate resin, urethane (meth) acrylate resin, and the like. These resins having an acrylate skeleton may be used alone, or 2 or more kinds may be used in combination.

The polyester (meth) acrylate resin is a polymer of an ester compound obtained by reacting (meth) acrylic acid with a compound having a hydroxyl group. The ester compound is not particularly limited, and may be a monofunctional (meth) acrylate having 1 (meth) acrylic group, or may be a polyfunctional (meth) acrylate having 2 or more (meth) acrylic groups. For example, the ester compound can be referred to the description about the compound described in paragraphs (0010) to (0012) of Japanese patent application laid-open No. 2010-85712. The polyester (meth) acrylate resin may be a copolymer formed of a plurality of ester compounds.

The epoxy (meth) acrylate resin is not particularly limited, and examples thereof include polymers obtained by reacting an epoxy resin with (meth) acrylic acid in the presence of a basic catalyst. The epoxy resin is not particularly limited, and may be appropriately selected from the epoxy resins having no acrylate skeleton. The epoxy (meth) acrylate resin may be a copolymer formed of a plurality of epoxy resins and a plurality of (meth) acrylic acids.

The (meth) acrylic acid derivative having a hydroxyl group is not particularly limited, and for example, the compound described in paragraph (0020) of Japanese patent application laid-open No. 2010-85712 can be referred to. The (meth) acrylic acid derivatives having a hydroxyl group may be used alone or in combination of 2 or more.

The liquid crystal layer LC is located between the 1 st substrate SUB1 and the 2 nd substrate SUB2, and is sandwiched between the 1 st alignment film AL1 and the 2 nd alignment film AL 2. The liquid crystal layer LC includes liquid crystal molecules LM. The liquid crystal layer LC is formed of a positive type (dielectric anisotropy is positive) liquid crystal material or a negative type (dielectric anisotropy is negative) liquid crystal material.

In such a display panel PNL, in an off state where no electric field is formed between the pixel electrode PE and the common electrode CE, the liquid crystal molecules LM are initially aligned in a predetermined direction between the 1 st alignment film AL1 and the 2 nd alignment film AL 2. In such an off state, light emitted from the illumination device BL to the display panel PNL is absorbed by the optical element OD1 and the optical element OD2, and dark display is performed. On the other hand, in an on state where an electric field is formed between the pixel electrode PE and the common electrode CE, the liquid crystal molecules LM are aligned in a direction different from the initial alignment direction by the electric field, and the alignment direction thereof is controlled by the electric field. In such an on state, part of the light from the illumination device BL passes through the optical element OD1 and the optical element OD2, and becomes bright display.

The alignment films (1 st alignment film AL1, 2 nd alignment film AL2) according to the embodiment are provided with a performance (alignment controllability) of initially aligning the liquid crystal molecules LM by applying a varnish for a photo-alignment film to the substrates (1 st substrate SUB1, 2 nd substrate SUB2), heating the varnish to convert the varnish into a polyimide film, and irradiating the polyimide film with polarized ultraviolet light.

< varnish for photo-alignment film >

The varnish for a photo-alignment film according to claim 1

The varnish for a photo-alignment film according to claim 1, which contains, in an organic solvent: a1 st polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 2 nd polyamic acid compound as a polyamic acid, which has a polarity higher than that of the 1 st polyamic acid compound. The tetracarboxylic acid ester residue has a cyclobutane skeleton. The diamine compound residue contains a1 st diamine compound residue comprising an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group.

As described later, the 1 st polyamic acid system compound having a diamine compound residue and a tetracarboxylic acid ester residue can be synthesized by: a diamine compound is reacted with a tetracarboxylic acid compound (tetracarboxylic dianhydride) to produce a precursor having a diamine compound residue and a tetracarboxylic acid residue, and the precursor is esterified. The above precursor can be used as the 2 nd polyamic acid compound as a polyamic acid.

Therefore, the 1 st polyamic acid system compound has a diamine compound residue and a tetracarboxylic acid ester residue, and the 2 nd polyamic acid system compound has a diamine compound residue and a tetracarboxylic acid residue.

< No. 1 Polyamic acid Compound >

The 1 st polyamic acid compound has: a tetracarboxylic acid ester residue having a cyclobutane skeleton. Such a tetracarboxylic acid ester residue having a cyclobutane skeleton can be represented by the following formula (1).

In the formula (1), R¹Are each alkyl, R^aEach hydrogen or alkyl. Here, the symbol "a" or "a" marked in the tetracarboxylic acid ester residue represented by the formula (1) indicates a bonding site with a diamine compound residue, which will be described in detail later.

R in the above formula (1)¹For example, an alkyl group having 1 to 6 carbon atoms, and the alkyl group is preferably a methyl group or an ethyl group. R in the above formula (1)^aWhen it is an alkyl group, R^aFor example, an alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group is particularly preferable as the alkyl group.

The 1 st polyamic acid compound has a diamine compound residue. The diamine compound residue contains a1 st diamine compound residue comprising an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group. Such a1 st diamine compound residue can be represented by the following formula (2-1).

In the formula (2-1), L¹Is a single bond or a1 st linking group, R²is-COOH or-N (R)³)₂(Here, R is³Each is hydrogen or alkyl), Ar¹Is an aromatic ring. I.e. in Ar as an aromatic ring¹To which 2 secondary amino groups are bonded and, directly or via L as the 1 st linking group¹To which R as a carboxyl group or an amino group is bonded². Here, the "+" symbol denoted in the residue of the 1 st diamine compound represented by the formula (2-1) denotes a bonding site with a tetracarboxylic acid ester residue (the "+" symbol denoted in the residue of the tetracarboxylic acid ester represented by the formula (1)).

In the above formula (2-1), L¹When it is the 1 st linking group, the 1 st linkageThe group is, for example, an aliphatic group or an aromatic group. The aliphatic group is, for example, an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 5 carbon atoms. The aromatic group is, for example, phenyl, naphthyl, anthryl, or pyrenyl.

In the above formula (2-1), R³When it is an alkyl group, R³For example, an alkyl group having 1 to 10 carbon atoms.

In the above formula (2-1), Ar as an aromatic ring¹For example, phenyl, naphthyl, anthracenyl, or pyrenyl.

When the 1 st polyamic acid compound has a tetracarboxylic acid ester residue represented by the above formula (1) and a1 st diamine compound residue represented by the above formula (2-1), the 1 st polyamic acid compound contains a structural unit (repeating unit) represented by the following formula (3-1).

In the formula (3-1), R¹And R^aAs defined for formula (1), L¹、R²And Ar¹The same as defined with respect to formula (2-1).

Production of No. 1 Polyamic acid Compound

The production of the No. 1 polyamic acid compound is as follows. First, a diamine compound is reacted with a tetracarboxylic acid compound (tetracarboxylic dianhydride) by a conventional method, thereby producing a polyamic acid-based compound having a diamine compound residue and a tetracarboxylic acid residue as a precursor. Next, the 1 st polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue can be produced by reacting a polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue as precursors with, for example, N-dimethylformamide dialkyl acetal.

The polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue can be produced by the method described in Japanese patent application laid-open No. 2000-273172.

The tetracarboxylic acid compound used for synthesizing the polyamic acid compound 1 can be represented by, for example, a tetracarboxylic acid compound having a cyclobutane skeleton represented by the following formula (4).

In the formula (4), R^aAs defined with respect to formula (1).

Examples of the tetracarboxylic acid compound having a cyclobutane skeleton represented by the above formula (4) include 1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride, 1, 2-dimethyl-1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride, 1, 3-dimethyl-1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride, and 1, 2, 3, 4-tetramethyl-1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride. The tetracarboxylic acid compound having a cyclobutane skeleton is preferably 1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride or 1, 3-dimethyl-1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride.

The diamine compound used for the synthesis of the 1 st polyamic acid compound can be represented by, for example, a diamine compound represented by the following formula (5-1).

In the formula (5-1), L¹、R²And Ar¹The same as defined with respect to formula (2-1).

Here, R²In the case of-COOH, for example, it is used in the synthesis of the polyamic acid compound of the 1 st embodiment in a state where the-COOH is protected by converting it into a benzyl ester group by using a benzyl halide such as benzyl bromide. The benzyl ester group can be converted to-COOH by a hydrogen addition reaction or the like using palladium as a catalyst.

In addition, R²is-NH₂I.e. primary amino group, in the reaction of the-NH group with benzyl chloroformate₂The compound is used for the synthesis of the 1 st polyamic acid compound in a state where it is protected by conversion into a benzyloxycarbonyl group. The benzyl ester group can be converted to-NH by a hydrogen addition reaction or the like using palladium as a catalyst₂。

Examples of the diamine compound represented by the above formula (5-1) include 2, 5-diaminobenzoic acid and 1, 2, 4-triaminobenzene.

< No. 2 Polyamic acid-based Compound >

The No. 2 polyamic acid compound is polyamic acid. Such polyamic acid has, for example, a diamine compound residue and a tetracarboxylic acid residue. The tetracarboxylic acid residue can be represented by the following formula (6).

In the formula (6), X¹An alicyclic skeleton, a chain skeleton, or an aromatic ring other than a cyclobutane skeleton or a cyclobutane skeleton.

Examples of the alicyclic skeleton other than the cyclobutane skeleton include a cyclopentane skeleton, a cyclohexane skeleton, a bicyclo [2, 2, 1] heptane skeleton, and a 2-methylbicyclo [2, 2, 1] heptane skeleton, examples of the chain skeleton include a butyl skeleton, and examples of the aromatic ring include a benzene ring.

The diamine compound residue that can be contained in the 2 nd polyamic acid compound can be represented by the following formula (7).

In the formula (7), Y¹Is Ar²Or Ar³-M-Ar⁴，Ar²、Ar³And Ar⁴Each independently is an aromatic ring, and M is either oxygen or sulfur, or an organic group formed by a combination of 2 or more of oxygen, nitrogen, sulfur, carbon, and hydrogen.

Ar as an aromatic ring in the above formula (7)²、Ar³And Ar⁴For example, phenyl, naphthyl, anthracenyl, or pyrenyl.

When the 2 nd polyamic acid compound has a tetracarboxylic acid residue represented by the above formula (6) and a diamine compound residue represented by the above formula (7), the 2 nd polyamic acid compound contains a structural unit (repeating unit) represented by the following formula (8).

In the formula (8), X¹As defined for formula (6), Y¹The same as defined with respect to formula (7).

Production of No. 2 Polyamic acid Compound

In the production of the 2 nd polyamic acid compound, the polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue, that is, the 2 nd polyamic acid compound as a polyamic acid can be produced by reacting a diamine compound with a tetracarboxylic acid compound (tetracarboxylic dianhydride) by a conventional method.

The tetracarboxylic acid compound used for synthesizing the polyamic acid compound of the 2 nd embodiment can be represented by, for example, a tetracarboxylic acid compound represented by the following formula (9).

In the formula (9), X¹The same as defined with respect to formula (6).

X represented by the above formula (9)¹The tetracarboxylic acid compound having a cyclobutane skeleton is, for example, the same as the tetracarboxylic acid compound represented by the above formula (4).

X represented by the above formula (9)¹Examples of the tetracarboxylic acid compound having an alicyclic skeleton other than a cyclobutane skeleton include 1, 2, 3, 4-cyclopentanetetracarboxylic dianhydride, 1, 2, 3, 5-cyclohexanetetracarboxylic dianhydride, and bicyclo [2, 2, 1] tetracarboxylic acid dianhydride]Heptane-2, 3, 5, 6-tetracarboxylic acid 2; 3, 5; 6-dianhydride, and 3, 5, 6-tricarboxynorbornane-2-acetic acid 2, 3; 5, 6-dianhydride, 3- (carboxymethyl) -1, 2, 4-cyclopentanetricarboxylic acid 1, 4: 2, 3 dianhydride.

X represented by the above formula (9)¹The tetracarboxylic acid compound which is a chain skeleton is, for example, meso-butane-1, 2, 3, 4-tetracarboxylic dianhydride.

X represented by the above formula (9)¹Tetracarboxylic acid compounds being aromatic radicals, e.g.Pyromellitic dianhydride.

In the tetracarboxylic acid compound represented by the above formula (9), X is contained in the total mole% (100 mole%) of the tetracarboxylic acid compound used for synthesizing the 2 nd polyamic acid compound¹The tetracarboxylic acid compound having a cyclobutane skeleton is less than 20 mol%, preferably less than 10 mol%. By making X¹The tetracarboxylic acid compound having a cyclobutane skeleton is less than 20 mol% of the total of the tetracarboxylic acid compounds used in the synthesis of the 2 nd polyamic acid compound, and an alignment film having a high resistance value can be formed.

The diamine compound used for the synthesis of the polyamic acid compound of the formula 2 can be represented by, for example, the following formula (10).

H₂N-Y¹-NH₂ (10)

In the formula (10), Y¹The same as defined with respect to formula (7).

Examples of the diamine compound represented by the above formula (10) include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2, 4-diaminotoluene, 2, 5-diaminotoluene, 3, 5-diaminotoluene, 1, 4-diamino-2-methoxybenzene, 2, 5-diaminop-xylene, 1, 3-diamino-4-chlorobenzene, 3, 5-diaminobenzoic acid, 1, 4-diamino-2, 5-dichlorobenzene, 4 '-diamino-1, 2-diphenylethane, 4' -diamino-2, 2 '-dimethylbenzyl, 4' -diaminodiphenylmethane, 3 '-diaminodiphenylmethane, 3, 4' -diaminodiphenylmethane, 4, 4 '-diamino-3, 3' -dimethyldiphenylmethane, 2 '-diaminostilbene, 4' -diaminodiphenyl ether, 3, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfide, 4 '-diaminodiphenyl sulfone, 3' -diaminodiphenyl sulfone, 4 '-diaminobenzophenone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 3, 5-bis (4-aminophenoxy) benzoic acid, 4' -bis (4-aminophenoxy) bibenzyl, 2-bis [ (4-aminophenoxy) methyl ] propane, 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (4-aminophenoxy) phenyl ] sulfone, 1-bis (4-aminophenyl) cyclohexane, α '-bis (4-aminophenyl) -1, 4-diisopropylbenzene, 9-bis (4-aminophenyl) fluorene, 2-bis (3-aminophenyl) hexafluoropropane, 2-bis (4-aminophenyl) hexafluoropropane, 4' -diaminodiphenylamine, 2, 4-diaminodiphenylamine, 1, 8-diaminonaphthalene, toluene, xylene, 1, 5-diaminonaphthalene, 1, 5-diaminoanthraquinone, 1, 3-diaminopyrene, 1, 6-diaminopyrene, 1, 8-diaminopyrene, 2, 7-diaminofluorene, 1, 3-bis (4-aminophenyl) tetramethyldisiloxane, benzidine, 2' -dimethylbenzidine, 1, 2-bis (4-aminophenyl) ethane, 1, 3-bis (4-aminophenyl) propane, 1, 4-bis (4-aminophenyl) butane, 1, 5-bis (4-aminophenyl) pentane, 1, 6-bis (4-aminophenyl) hexane, 1, 7-bis (4-aminophenyl) heptane, 1, 8-bis (4-aminophenyl) octane, 1, 9-bis (4-aminophenyl) nonane, 1, 6-bis (4-aminophenyl) hexane, 1, 10-bis (4-aminophenyl) decane, 1, 3-bis (4-aminophenoxy) propane, 1, 4-bis (4-aminophenoxy) butane, 1, 5-bis (4-aminophenoxy) pentane, 1, 6-bis (4-aminophenoxy) hexane, 1, 7-bis (4-aminophenoxy) heptane, 1, 8-bis (4-aminophenoxy) octane, 1, 9-bis (4-aminophenoxy) nonane, 1, 10-bis (4-aminophenoxy) decane, propane-1, 3-dicarboxylic acid bis (4-aminophenyl) ester, butane-1, 4-dicarboxylic acid bis (4-aminophenyl) ester, pentane-1, 5-dicarboxylic acid bis (4-aminophenyl) ester, Hexane-1, 6-dicarboxylic acid di (4-aminophenyl) ester, heptane-1, 7-dicarboxylic acid di (4-aminophenyl) ester, octane-1, 8-dicarboxylic acid di (4-aminophenyl) ester, nonane-1, 9-dicarboxylic acid di (4-aminophenyl) ester, decane-1, 10-dicarboxylic acid di (4-aminophenyl) ester, 1, 3-bis [4- (4-aminophenoxy) phenoxy ] propane, 1, 4-bis [4- (4-aminophenoxy) phenoxy ] butane, 1, 5-bis [4- (4-aminophenoxy) phenoxy ] pentane, 1, 6-bis [4- (4-aminophenoxy) phenoxy ] hexane, 1, 7-bis [4- (4-aminophenoxy) phenoxy ] heptane, 1, 8-bis [4- (4-aminophenoxy) phenoxy ] octane, 1, 9-bis [4- (4-aminophenoxy) phenoxy ] nonane, and 1, 10-bis [4- (4-aminophenoxy) phenoxy ] decane. Examples of the diamine represented by formula (10) are shown below (in the following examples, n is an integer of 1 to 10).

< organic solvent >

As the organic solvent for dissolving or dispersing the 1 st and 2 nd polyamic acid compounds, N-dimethylformamide, N, n-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylsulfoxide, gamma-butyrolactone, 1, 3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, 1, 2 propylene carbonate, diethylene glycol dimethyl ether, and 4-hydroxy-4-methyl-2-pentanone, and butyl cellosolve.

In some embodiments, the ratio of the 1 st polyamic acid compound to the 2 nd polyamic acid compound in the varnish for a photo-alignment film is 6: 4 to 2: 8, preferably 4: 6 to 3: 7.

The varnish for a photo-alignment film according to claim 1 is a varnish in which a1 st polyamic acid compound (as a polyamic acid ester) having a tetracarboxylic acid ester residue and a 2 nd polyamic acid compound (as a polyamic acid) coexist. In this case, the polyamic acid has a surface energy greater than that of the polyamic acid ester. That is, the polyamic acid has a polarity higher than that of the polyamic acid ester. Therefore, the 1 st polyamic acid compound and the 2 nd polyamic acid compound are phase separated.

Referring to fig. 2, when the varnish for a photo-alignment film according to the first aspect 1 is applied on the pixel electrode PE and the 2 nd insulating film 12 of the 1 st substrate SUB1, the 2 nd polyamic acid compound has high affinity with ITO and IZO forming the pixel electrode PE and an inorganic insulating material such as silicon oxide, silicon nitride, or silicon oxynitride forming the 2 nd insulating film 12, and therefore the 2 nd polyamic acid compound forms a lower layer and the 1 st polyamic acid compound forms an upper layer, and comes into contact with the liquid crystal layer LC and the seal portion SE.

Further, when the varnish for a photo alignment film according to the 1 st aspect is applied on the protective layer OC of the 2 nd substrate SUB2, the 2 nd polyamic acid compound forms a lower layer and contacts the protective layer OC, and the 1 st polyamic acid compound forms an upper layer and contacts the liquid crystal layer LC and the sealing portion SE, because the 2 nd polyamic acid compound has high affinity with the protective layer OC using an organic resin.

The varnish for a photo-alignment film applied to a coating object and separated into two phases is heated at a temperature of about 200 ℃ to perform imidization, and the imidized two-layer film is photo-aligned to provide an alignment film, i.e., a photo-alignment film. The photo-alignment treatment can be performed by irradiating the imidized film with polarized ultraviolet light having a wavelength of 254nm to 365 nm. When the imide compound of the 1 st polyamic acid compound forming the upper layer is subjected to photo-alignment treatment, the cyclobutane skeleton is cracked, and the imide compound can be imparted with a property (alignment controllability) of initial alignment of liquid crystal molecules. The 1 st substrate SUB1 and the 2 nd substrate SUB2 provided with the photo-oriented imidized film may be further heated at a temperature of about 200 ℃.

In the imidization reaction by heating as described above, the imidization ratio is 70% to 90%. Therefore, when the 1 st polyamic acid compound is imidized with the mole percentage of the carboxylic acid ester group contained in the tetracarboxylic acid ester residue in the 1 st polyamic acid compound being 100 mole%, the carboxylic acid ester group as an imidized unreacted portion in the imide compound of the 1 st polyamic acid compound remains in the range of 10 to 30 mole%.

Similarly, when the 2 nd polyamic acid compound is imidized with the mole percentage of the carboxyl group contained in the tetracarboxylic acid residue in the 2 nd polyamic acid compound being 100 mole%, the carboxyl group as the non-imidized part in the imide compound of the 2 nd polyamic acid compound remains in the range of 10 mole% to 30 mole%.

Fig. 4 is a schematic view showing a photo-alignment film (1 st alignment film AL1) having a two-layer structure according to an embodiment. The 1 st alignment film AL1 is formed on the 2 nd insulating film 12, and is formed of an upper layer AL1-1 and a lower layer AL 1-2. Here, since the boundary between the upper layer AL1-1 and the lower layer AL1-2 of the 1 st alignment film AL1 is unclear, the boundary is indicated by a dotted line in fig. 4.

As described above, in the photo-alignment film having a two-layer structure formed using the varnish for a photo-alignment film according to claim 1, the imide of the 2 nd polyamic acid compound forms a lower layer (on the insulating substrate side), and the imide of the 1 st polyamic acid compound forms an upper layer (on the liquid crystal and sealing substrate side).

In some embodiments, the imide compound (polyimide) of the 1 st polyamic acid based compound forming the upper layer has a structural unit (repeating unit) represented by the following formula (11-1).

In the formula (11-1), R^aAs defined for formula (1), L¹、R²And Ar¹The same as defined with respect to formula (2-1).

In some embodiments, the imide compound (polyimide) of the second polyamic acid compound forming the lower layer 2 has a structural unit (repeating unit) represented by the following formula (12).

In the formula (12), X¹As defined for formula (6), Y¹The same as defined with respect to formula (7).

Therefore, the imide compound (polyimide) of the 1 st polyamic acid compound forming the upper layer has an aromatic ring to which a carboxyl group or an amino group is bonded directly or via the 1 st linking group, and the carboxyl group or the amino group is bonded to the sealing portion, and thus is strongly bonded to the sealing portion.

Further, since the imide compound of the 1 st polyamic acid compound forming the upper layer has a cyclobutane skeleton, the cyclobutane skeleton is cracked by the photo-alignment treatment, and a property (alignment controllability) for initial alignment of liquid crystal molecules can be imparted.

Since the carboxyl group remains as an unreacted imidized portion in the imide compound of the second polyamic acid compound 2 forming the lower layer, the carboxyl group is bonded to the second insulating film 2, the pixel electrode, the protective layer, and the like. Therefore, the imide compound of the 2 nd polyamic acid compound is strongly bonded to these materials.

Therefore, by using the varnish for a photo-alignment film according to claim 1, a photo-alignment film having improved adhesion strength to a sealing portion can be formed without deteriorating performance of initially aligning liquid crystal molecules of a liquid crystal layer.

In some embodiments, the 1 st polyamic acid compound residue in the varnish for a photoalignment film according to the 1 st aspect further comprises: a 2 nd diamine compound residue having 2 secondary amino groups and having a plurality of (for example, 2) aromatic rings bonded via a 2 nd linking group. Such a 2 nd diamine compound residue can be represented by the following formula (2-2).

In the formula (2-2), L²Is a 2 nd linking group, Ar⁵And Ar⁶Each is an aromatic ring. Namely, Ar as a plurality of aromatic rings⁵And Ar⁶Has 2 secondary amino groups and is bonded via a 2 nd linking group. Here, the "+" symbol denoted in the residue of the 2 nd diamine compound represented by the formula (2-2) denotes a bonding site with a tetracarboxylic acid ester residue (the "+" symbol denoted in the residue of the tetracarboxylic acid ester represented by the formula (1)).

The 2 nd linking group contains, for example, an alkylene group. The 2 nd linking group (L) in the above formula (2-2)²) For example is-A¹-R⁴-A²-，A¹And A²Each independently of the other being a single bond or oxygen or sulfur, R⁴Is an alkylene group having 1 to 10 carbon atoms. R⁴Alkylene groups having 1 to 5 carbon atoms are preferred.

In the above formula (2-2), Ar as an aromatic ring⁵And Ar⁶For example, phenyl, naphthyl, anthracenyl, or pyrenyl.

When the 1 st polyamic acid compound has a tetracarboxylic acid residue represented by the above formula (1) and a 2 nd diamine compound residue represented by the above formula (2-2), the 1 st polyamic acid compound has a structural unit (repeating unit) represented by the following formula (3-2).

In the formula (3-2), R^aAs defined for formula (1), L²、Ar⁵And Ar⁶The same as defined with respect to formula (2-2).

The diamine compound used for the synthesis of the 1 st polyamic acid compound can be represented by, for example, a diamine compound represented by the following formula (13).

H₂N-Ar⁵-L²-Ar⁶-NH₂ (13)

In the formula (13), L²、Ar⁵And Ar⁶The same as defined with respect to formula (2-2).

Examples of the diamine compound represented by the above formula (13) include 1, 2-bis (4-aminophenyl) ethane and 1, 2-bis (4-aminophenoxy) ethane.

In some embodiments, the 1 st polyamic acid compound has a1 st diamine compound residue represented by formula (2-1) above, and a 2 nd diamine compound residue represented by formula (2-2) above. The imide compound of the 1 st polyamic acid compound having the 2 nd diamine compound residue represented by the above formula (2-2) has not only the structural unit represented by the above formula (11-1) but also the structural unit represented by the following formula (11-2).

In the formula (11-2), R^aAs defined for formula (1), L²、Ar⁵And Ar⁶The same as defined with respect to formula (2-2).

Therefore, the photoalignment film including the imide compound having the structural unit represented by the formula (11-1) and the structural unit represented by the formula (11-2) has not only the characteristics of the photoalignment film including the imide compound having the structural unit represented by the formula (11-1) but also the following characteristics.

The 1 st polyamic acid compound forming the upper layer further has a plurality of aromatic rings bonded through the 2 nd linking group, and therefore phase separation from the 2 nd polyamic acid compound is more likely to occur. Therefore, the imide compound of the 1 st polyamic acid compound that initially aligns the liquid crystal molecules can be easily formed as an upper layer.

In addition, the imide compound of the 1 st polyamic acid compound forming the upper layer has a plurality of aromatic rings bonded through the 2 nd linking group, and thus flexibility can be imparted. Therefore, even if an external force is applied to the liquid crystal display device, the imide compound absorbs the impact due to the external force, and the seal portion and the alignment film are less likely to be peeled off.

In some embodiments, a carboxyl group or an amino group is further bonded to at least 1 (typically each aromatic ring) of the plurality of aromatic rings of the 2 nd diamine compound residue, either directly or via the 3 rd linking group. Such a diamine compound residue can be represented, for example, as a 3 rd diamine compound residue. The 3 rd diamine compound residue can be represented by, for example, the following formula (2-3).

In the formula (2-3), L²、Ar⁵And Ar⁶R is the same as defined for the formula (2-2)²The same as defined with respect to the formula (2-1)，L³Is a single bond or a 3 rd linking group. I.e. at least 1 (Ar) in a plurality of aromatic rings⁵And Ar⁶) A carboxyl group or an amino group is further bonded to the above group directly or through a 3 rd linking group. Here, the "+" symbol denoted in the residue of the 3 rd diamine compound represented by the formula (2-3) denotes a bonding site with a tetracarboxylic acid ester residue (the "+" symbol denoted in the residue of the tetracarboxylic acid ester represented by the formula (1)).

In the above formula (2-3), L³In the case of the 3 rd linking group, the 3 rd linking group is, for example, an aliphatic group or an aromatic group. The aliphatic group is, for example, an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 5 carbon atoms. The aromatic group is, for example, phenyl, naphthyl, anthryl, or pyrenyl.

When the 1 st polyamic acid compound has a tetracarboxylic acid residue represented by the above formula (1) and a 3 rd diamine compound residue represented by the above formula (2-3), the 1 st polyamic acid compound has a structural unit (repeating unit) represented by the following formula (3-3).

In the formula (3-3), R^aAs defined for formula (1), L²、Ar⁵And Ar⁶R is the same as defined for the formula (2-2)²As defined for formula (2-1), L³The same as defined with respect to the formula (2-3).

The diamine compound used for the synthesis of the 1 st polyamic acid compound can be represented by, for example, a diamine compound represented by the following formula (14).

In the formula (14), L²、Ar⁵And Ar⁶R is the same as defined for the formula (2-2)²As defined for formula (2-1), L³And are defined with respect to formula (2-3)Are the same as above.

Examples of the diamine compound represented by the above formula (14) include 1, 2-bis (4-amino-3-carboxyphenyl) ethane and 1, 2-bis (4-amino-3-carboxyphenoxy) ethane.

In some embodiments, the 1 st polyamic acid compound has not only the 1 st diamine compound residue represented by the above formula (2-1) but also the 3 rd diamine compound residue represented by the above formula (2-3). The imide compound of the 1 st polyamic acid compound having a diamine compound residue represented by the above formula (2-3) has not only the structural unit represented by the above formula (11-1) but also the structural unit represented by the following formula (11-3).

In the formula (11-3), R^aAs defined for formula (1), L²、Ar⁵And Ar⁶R is the same as defined for the formula (2-2)²As defined for formula (2-1), L³The same as defined with respect to the formula (2-3).

Therefore, the photoalignment film including the imide compound having the structural unit represented by the above formula (11-1) and the structural unit represented by the above formula (11-3) has not only the characteristics of the photoalignment film including the imide compound having the structural unit represented by the above formula (11-1) but also the following characteristics.

In addition, the imide compound of the 1 st polyamic acid compound forming the upper layer is further bonded with a carboxyl group or an amino group directly or via the 3 rd linking group to at least 1 of the plurality of aromatic rings, and the carboxyl group or the amino group is bonded to the sealing portion, and thus is strongly bonded to the sealing portion.

The varnish for photo-alignment film according to claim 2

The varnish for a photo-alignment film according to claim 2, wherein the organic solvent contains: a 3 rd polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded; and a 4 th polyamic acid compound as a polyamic acid having a polarity higher than that of the 3 rd polyamic acid compound. The tetracarboxylic acid residue has a cyclobutane skeleton.

The 3 rd polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded can be synthesized by: a diamine compound is reacted with a tetracarboxylic acid compound (tetracarboxylic dianhydride) to produce a precursor having a diamine compound residue and a tetracarboxylic acid residue, and half of the carboxyl groups contained in the precursor are esterified. The above-mentioned precursor can be used as the 4 th polyamic acid compound as a polyamic acid.

Therefore, the 3 rd polyamic acid compound has a diamine compound residue and a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded, and the 4 th polyamic acid compound has a diamine compound residue and a tetracarboxylic acid residue.

< No. 3 Polyamic acid-based Compound >

The 3 rd polyamic acid compound has a tetracarboxylic acid residue having a cyclobutane skeleton and having a carboxyl group and a carboxylate group bonded thereto. Such a tetracarboxylic acid residue can be represented by the following formula (15-1).

In the formula (15-1), R^aR is as defined for formula (1)⁵Is an alkyl group. Here, the symbol "in color" denoted by the tetracarboxylic acid residue represented by the formula (15-1) denotes a bonding site with a diamine compound residue (the symbol "in color" denoted by the diamine compound residue represented by the formula (7)).

In the formula (15-1), R⁵For example, an alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group is particularly preferable as the alkyl group.

The 3 rd polyamic acid compound may contain not only the above formula (15-1) but also a tetracarboxylic acid residue represented by the following formula (15-2) and a tetracarboxylic acid ester residue represented by the above formula (1).

In the formula (15-2), R^aAs defined with respect to formula (1). Here, the symbol "in color" denoted by the tetracarboxylic acid residue represented by the formula (15-2) denotes a bonding site with a diamine compound residue (the symbol "in color" denoted by the diamine compound residue represented by the formula (7)).

The 3 rd polyamic acid compound has a diamine compound residue. The diamine compound residue may be represented by the above formula (7).

When the 3 rd polyamic acid compound has a tetracarboxylic acid residue represented by the above formula (15-1) and a diamine compound residue represented by the above formula (7), the 3 rd polyamic acid compound has a structural unit (repeating unit) represented by the following formula (16).

In the formula (16), R⁵As defined for formula (15-1), Y¹The same as defined with respect to formula (7).

The tetracarboxylic acid compound used for synthesizing the 3 rd polyamic acid compound can be represented by, for example, the tetracarboxylic acid compound represented by the formula (4).

The diamine compound used for the synthesis of the 3 rd polyamic acid compound can be represented by, for example, a diamine compound represented by the above formula (10).

In the 3 rd polyamic acid compound, the ratio of the carboxyl group to the carboxylic acid ester group is, for example, 1: 3 to 3: 1, preferably 1: 2 to 2: 1. In some embodiments, the ratio of carboxyl groups to carboxylate groups in the 3 rd polyamic acid compound is, for example, 1: 1.

< 4 th Polyamic acid Compound >

The 4 th polyamic acid compound has the same composition as the 2 nd polyamic acid compound, and therefore, a repetitive description thereof will be omitted.

The organic solvent for dissolving or dispersing the 3 rd and 4 th polyamic acid compounds may be the organic solvent for dissolving or dispersing the 1 st and 2 nd polyamic acid compounds as described above.

In some embodiments, the ratio of the 3 rd polyamic acid compound to the 4 th polyamic acid compound in the varnish for a photo-alignment film is 4: 6 to 2: 8, preferably 4: 6 to 3: 7.

The varnish for a photo-alignment film according to claim 2 is characterized in that the 3 rd polyamic acid compound having a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded and the 4 th polyamic acid compound (having a tetracarboxylic acid residue) as a polyamic acid coexist. In this case, the 4 th polyamic acid compound having a tetracarboxylic acid residue has a surface energy greater than that of the 3 rd polyamic acid compound having a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded. That is, the 4 th polyamic acid compound has a polarity higher than that of the 3 rd polyamic acid compound. Therefore, the 3 rd polyamic acid compound and the 4 th polyamic acid compound are phase separated.

When the varnish for a photo-alignment film according to claim 2 is applied to a coating target, the 4 th polyamic acid compound has high affinity with the pixel electrode PE, the 2 nd insulating film 12, and the protective layer OC, and therefore the 4 th polyamic acid compound forms a lower layer, and the 3 rd polyamic acid compound forms an upper layer, and comes into contact with the liquid crystal layer LC and the seal portion SE.

The varnish for a photo-alignment film applied to a coating object and separated into two phases is heated at a temperature of about 200 ℃ to perform imidization, and the imidized two-layer film is photo-aligned to provide an alignment film, i.e., a photo-alignment film.

In the imidization reaction by heating as described above, the imidization ratio is 70% to 90%. Therefore, when the 3 rd polyamic acid compound is imidized with the molar percentage of the carboxyl group and the carboxylic acid ester group contained in the 3 rd polyamic acid compound being 100 mol%, the carboxyl group and the carboxylic acid ester group as the non-imidized part remain in the imide compound of the 3 rd polyamic acid compound in the range of 10 mol% to 30 mol%.

Similarly, when the 4 th polyamic acid compound is imidized with the mole percentage of the carboxyl group contained in the tetracarboxylic acid residue in the 4 th polyamic acid compound being 100 mole%, the carboxyl group as the non-imidized part in the imide compound of the 4 th polyamic acid compound remains in the range of 10 mole% to 30 mole%.

As described above, in the photo-alignment film having a two-layer structure formed using the varnish for a photo-alignment film according to claim 2, the imide compound of the 4 th polyamic acid compound forms a lower layer (on the insulating substrate side), and the imide compound of the 3 rd polyamic acid compound forms an upper layer (on the liquid crystal and sealing substrate sides).

In some embodiments, the imide compound (polyimide) of the 3 rd polyamic acid compound forming the upper layer has a structural unit (repeating unit) represented by the following formula (17).

In the formula (17), R^aAs defined for formula (1), Y¹The same as defined with respect to formula (7).

In some embodiments, the imide compound (polyimide) of the 4 th polyamic acid based compound forming the lower layer has a structural unit (repeating unit) represented by the above formula (12).

Therefore, since the imide compound of the 3 rd polyamic acid compound forming the upper layer has a cyclobutane skeleton, the cyclobutane skeleton is cracked by the photo-alignment treatment, and a property (alignment controllability) of initially aligning the liquid crystal molecules can be imparted.

In addition, since the carboxyl group as an unreacted imidized portion remains in the imide compound of the 3 rd polyamic acid compound forming the upper layer, the carboxyl group is bonded to the sealing portion. Therefore, the imide compound of the 3 rd polyamic acid compound is strongly adhered to the sealing portion.

In the imide compound of the 4 th polyamic acid compound forming the lower layer, a carboxyl group as an unreacted portion of imidization remains, and therefore, the carboxyl group is bonded to a pixel electrode, a protective layer, and the like. Therefore, the imide compound of the 4 th polyamic acid compound strongly adheres to these materials.

Therefore, by using the varnish for a photo-alignment film according to claim 2, a photo-alignment film having improved adhesion strength to the sealing portion can be formed without deteriorating the performance of initially aligning the liquid crystal molecules of the liquid crystal layer.

In some embodiments, the 3 rd polyamic acid compound may have not only the diamine compound residue represented by the above formula (7) but also at least one of the 1 st diamine compound residue represented by the above formula (2-1), the 2 nd diamine compound residue represented by the above formula (2-2), and the 3 rd diamine compound residue represented by the above formula (2-3), or may have at least one of the 1 st to 3 rd diamine compound residues represented by the above formulae (2-1) to (2-3) in place of the diamine compound residue represented by the above formula (7). The effect described in the 1 st polyamic acid compound can be obtained in the 3 rd polyamic acid compound by providing the 1 st to 3 rd diamine compound residues.

The varnish for photo-alignment film according to claim 3

The varnish for a photo-alignment film according to claim 3, which contains, in an organic solvent: a 5 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue; a 6 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 7 th polyamic acid compound as a polyamic acid having a polarity higher than those of the 5 th and 6 th polyamic acid compounds. The tetracarboxylic acid residue and the tetracarboxylic acid ester residue each have a cyclobutane skeleton. The 5 th polyamic acid compound is contained in a range of 25 parts by weight or more and 75 parts by weight or less, based on 100 parts by weight of the total of the 5 th and 6 th polyamic acid compounds.

The 5 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue can be produced by reacting a diamine compound with a tetracarboxylic acid compound (tetracarboxylic dianhydride). The 6 th polyamic acid system compound having a diamine compound and a tetracarboxylic acid ester residue can be synthesized by: a polyamic acid-based compound having a diamine compound residue and a tetracarboxylic acid residue is used as a precursor, and the precursor is esterified. For the polyamic acid, the above-described precursor can be used as the 7 th polyamic acid compound.

Therefore, the 5 th and 7 th polyamic acid compounds have a diamine compound residue and a tetracarboxylic acid residue, and the 6 th polyamic acid compound has a diamine compound residue and a tetracarboxylic acid ester residue.

< 5 th Polyamic acid Compound >

The 5 th polyamic acid compound has: a tetracarboxylic acid residue having a cyclobutane skeleton. Such a tetracarboxylic acid residue having a cyclobutane skeleton can be represented by the above formula (15-2).

The 5 th polyamic acid compound has a diamine compound residue. Such a diamine compound residue can be represented by the above formula (7).

When the 5 th polyamic acid compound has a tetracarboxylic acid residue represented by the above formula (15-2) and a diamine compound residue represented by the above formula (7), the 5 th polyamic acid compound has a structural unit (repeating unit) represented by the following formula (18).

In the formula (18), R^aAs defined for formula (1), Y¹The same as defined with respect to formula (7).

The tetracarboxylic acid compound used for synthesizing the 5 th polyamic acid compound can be represented by, for example, the tetracarboxylic acid compound represented by the formula (4).

The diamine compound used for the synthesis of the 5 th polyamic acid compound can be represented by, for example, the diamine compound represented by the formula (10).

< 6 th Polyamic acid Compound >

The 6 th polyamic acid compound has: a tetracarboxylic acid ester residue having a cyclobutane skeleton. Such a tetracarboxylic acid ester residue having a cyclobutane skeleton can be represented by the above formula (1).

The 6 th polyamic acid compound has a diamine compound residue. Such a diamine compound residue can be represented by the above formula (7).

When the 6 th polyamic acid compound has a tetracarboxylic acid ester residue represented by the above formula (1) and a diamine compound residue represented by the above formula (7), the 6 th polyamic acid compound has a structural unit (repeating unit) represented by the following formula (19).

In the formula (19), R¹And R^aAs defined for formula (1), Y¹The same as defined with respect to formula (7).

The tetracarboxylic acid compound used for synthesizing the 6 th polyamic acid compound can be represented by, for example, the tetracarboxylic acid compound represented by the formula (4).

The diamine compound used for the synthesis of the 6 th polyamic acid compound can be represented by, for example, the diamine compound represented by the formula (10).

< 7 th Polyamic acid Compound >

The 7 th polyamic acid compound is polyamic acid.

The 7 th polyamic acid compound has the same constitution as the 2 nd polyamic acid compound but has a higher polarity than the 5 th polyamic acid compound. Such a 7 th polyamic acid compound has high polarity due to the presence of more oxygen in the diamine compound residue in the 7 th polyamic acid compound than in the 5 th polyamic acid compound, for example. That is, the 7 th polyamic acid compound has a surface energy greater than that of the 5 th polyamic acid compound by the presence of more oxygen in the diamine compound residue.

The tetracarboxylic acid compound used for synthesizing the 7 th polyamic acid compound can be represented by, for example, the tetracarboxylic acid compound represented by the formula (9).

The diamine compound used for synthesizing the 7 th polyamic acid compound can be represented by, for example, the diamine compound represented by the formula (10), and is preferably a diamine compound containing a large amount of oxygen.

As the organic solvent for dissolving or dispersing the 5 th to 7 th polyamic acid compounds, the organic solvents for dissolving or dispersing the 1 st and 2 nd polyamic acid compounds as described above can be used.

In some embodiments, the weight ratio of the 5 th polyamic acid compound to the 6 th polyamic acid compound in the varnish for a photo-alignment film is 25 parts by weight or more and 75 parts by weight or less, based on 100 parts by weight of the total of the 5 th and 6 th polyamic acid compounds. In the varnish for the photo-alignment film, the total weight of the 5 th and 6 th polyamic acid compounds and the weight of the 6 th polyamic acid compound are, for example, 4: 6 to 2: 8, preferably 4: 6 to 3: 7.

The varnish for a photo-alignment film according to claim 3 is characterized in that the 5 th polyamic acid compound (as a polyamic acid) having a tetracarboxylic acid residue, the 6 th polyamic acid compound (as a polyamic acid ester) having a tetracarboxylic acid ester residue, and the 7 th polyamic acid compound (as a polyamic acid) having a tetracarboxylic acid residue coexist. In this case, the polyamic acid has a surface energy greater than that of the polyamic acid ester. That is, the polyamic acid has a polarity higher than that of the polyamic acid ester. Therefore, the 6 th polyamic acid compound and the 7 th polyamic acid compound are phase-separated.

In addition, the 5 th and 7 th polyamic acid compounds are both polyamic acids, but as described above, the 7 th polyamic acid compound is configured to have a surface energy greater than that of the 5 th polyamic acid compound. Therefore, the 5 th polyamic acid compound and the 7 th polyamic acid compound are phase separated.

Here, the 5 th polyamic acid compound and the 6 th polyamic acid compound may be phase-separated from the 7 th polyamic acid compound, and the 5 th polyamic acid compound and the 6 th polyamic acid compound may be mixed with each other.

When the varnish for a photo-alignment film according to claim 3 is applied to a coating target, the 7 th polyamic acid compound has high affinity with the pixel electrode PE, the 2 nd insulating film 12, and the protective layer OC, and therefore the 7 th polyamic acid compound forms a lower layer, and the 5 th and 6 th polyamic acid compounds form an upper layer, and come into contact with the liquid crystal layer LC and the sealing portion SE.

In the imidization reaction by heating as described above, the imidization ratio is 70% to 90%. Therefore, when the 6 th polyamic acid compound is imidized with the mole percentage of the carboxylic acid ester group contained in the tetracarboxylic acid ester residue in the 6 th polyamic acid compound being 100 mole%, the carboxylic acid ester group as an imidized unreacted portion in the imide compound of the 6 th polyamic acid compound remains in the range of 10 to 30 mole%.

Similarly, when the molar percentages of the carboxyl groups contained in the tetracarboxylic acid residues in the 5 th and 7 th polyamic acid compounds are taken as 100 mol%, respectively, if the 5 th and 7 th polyamic acid compounds are imidized, the carboxyl groups that are non-imidized sites in the imide compounds of the 5 th and 7 th polyamic acid compounds remain in the range of 10 mol% to 30 mol%, respectively.

As described above, in the photo-alignment film having a two-layer structure formed using the varnish for a photo-alignment film according to claim 3, the imide of the 7 th polyamic acid compound forms a lower layer (on the insulating substrate side), and the imide of the 5 th and 6 th polyamic acid compounds forms an upper layer (on the liquid crystal and sealing substrate sides), respectively.

In some embodiments, the imide compound (polyimide) of the 5 th polyamic acid compound forming the upper layer has a structural unit (repeating unit) represented by the above formula (17).

In some embodiments, the imide compound (polyimide) of the 6 th polyamic acid compound forming the upper layer has a structural unit (repeating unit) represented by the above formula (17).

In some embodiments, the imide compound (polyimide) of the 7 th polyamic acid based compound forming the lower layer has a structural unit (repeating unit) represented by the above formula (12).

Therefore, since the imide compounds of the 5 th and 6 th polyamic acid compounds forming the upper layer have a cyclobutane skeleton, the cyclobutane skeleton is cracked by the photo-alignment treatment, and the properties (alignment controllability) for initial alignment of the liquid crystal molecules are imparted.

In addition, since the carboxyl group as an unreacted imidized portion remains in the imide compound of the 5 th polyamic acid compound forming the upper layer, the carboxyl group is bonded to the sealing portion. Therefore, the imide compound of the 5 th polyamic acid compound is strongly bonded to the sealing portion.

Since the carboxyl group remains as an unreacted imidized portion in the imide compound of the 7 th polyamic acid compound forming the lower layer, the carboxyl group is bonded to the 2 nd insulating film, the pixel electrode, the protective layer, and the like. Therefore, the imide compound of the 7 th polyamic acid compound is strongly bonded to these materials.

Therefore, by using the varnish for a photo-alignment film according to claim 3, a photo-alignment film having improved adhesion strength to a sealing portion can be formed without deteriorating performance of initially aligning liquid crystal molecules of a liquid crystal layer.

Here, the 5 th polyamic acid compound is included in a range of 25 parts by weight or more and 75 parts by weight or less, with the total of the 5 th and 6 th polyamic acid compounds being 100 parts by weight. When the total amount of the 5 th and 6 th polyamic acid compounds is set to 100 parts by weight, imide compounds (polyimide) of the 5 th polyamic acid compound forming the upper layer are decreased when the amount of the 5 th polyamic acid compound is set to less than 25 parts by weight. As a result, the upper layer has a reduced number of carboxyl groups, and thus, the upper layer is difficult to bond to the sealing portion, and may not be firmly bonded to the sealing portion.

When the total amount of the 5 th and 6 th polyamic acid compounds is 100 parts by weight, if the 5 th polyamic acid compound is more than 75 parts by weight, the 5 th and 6 th polyamic acid compounds forming the upper layer and the 7 th polyamic acid compound forming the lower layer are less likely to be phase-separated, and the cyclobutane skeleton is cracked by the photo-alignment treatment, so that it is difficult to impart an alignment control ability, and it may be difficult to initially align the liquid crystal molecules LM.

In some embodiments, the 5 th and 6 th polyamic acid compounds may have not only the residue of the diamine compound represented by the above formula (7) but also at least one of the 1 st residue of the diamine compound represented by the above formula (2-1), the 2 nd residue of the diamine compound represented by the above formula (2-2), and the 3 rd residue of the diamine compound represented by the above formula (2-3), respectively, or may have at least one of the 1 st to 3 rd residues of the diamine compounds represented by the above formulae (2-1) to (2-3) in place of the residue of the diamine compound represented by the above formula (7). The effects described in the 1 st polyamic acid compound can be obtained in the 5 th and 6 th polyamic acid compounds by providing the 1 st to 3 rd diamine compound residues.

The varnish for a photo-alignment film according to claim 4

The varnish for a photo-alignment film according to claim 4, which contains, in an organic solvent: a 8 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue, and a 9 th polyamic acid compound as a polyamic acid having a polarity higher than that of the 8 th polyamic acid compound. The tetracarboxylic acid ester residue has a cyclobutane skeleton. The diamine compound residue contains: a 3 rd diamine compound residue having 2 secondary amino groups and having a plurality of aromatic rings bonded via a 2 nd linking group. The aromatic ring of the 3 rd diamine compound residue is further bonded with a carboxyl group or an amino group directly or through a 3 rd linking group.

The 8 th polyamic acid system compound having a diamine compound residue and a tetracarboxylic acid ester residue can be synthesized by: a diamine compound is reacted with a tetracarboxylic acid compound (tetracarboxylic dianhydride) to produce a precursor having a diamine compound residue and a tetracarboxylic acid residue, and the precursor is esterified. The above precursor can be used as the 9 th polyamic acid compound as a polyamic acid.

Therefore, the 9 th polyamic acid compound has a diamine compound residue and a tetracarboxylic acid residue, and the 8 th polyamic acid compound has a diamine compound residue and a tetracarboxylic acid ester residue.

< 8 th Polyamic acid Compound >

The 8 th polyamic acid compound has: a tetracarboxylic acid ester residue having a cyclobutane skeleton. Such a tetracarboxylic acid ester residue having a cyclobutane skeleton can be represented by the above formula (1).

The 8 th polyamic acid compound has a diamine compound residue. The diamine compound residue contains: a 3 rd diamine compound residue having 2 secondary amino groups and having a plurality of aromatic rings bonded via a 2 nd linking group. A carboxyl group or an amino group is further bonded to the aromatic ring of the 3 rd diamine compound residue directly or through a 3 rd linking group. Such a 3 rd diamine compound residue can be represented by the above formula (2-3).

When the 8 th polyamic acid compound has a tetracarboxylic acid ester residue represented by the above formula (1) and a 3 rd diamine compound residue represented by the above formula (2-3), the 8 th polyamic acid compound has a structural unit (repeating unit) represented by the above formula (3-3).

The tetracarboxylic acid compound used for synthesizing the 8 th polyamic acid compound can be represented by, for example, the tetracarboxylic acid compound represented by the formula (4).

The diamine compound used for the synthesis of the 8 th polyamic acid compound can be represented by, for example, the diamine compound represented by the above formula (13).

< 9 th Polyamic acid Compound >

The 9 th polyamic acid compound has the same structure as the 2 nd polyamic acid compound, and therefore, a repetitive description thereof will be omitted.

As the organic solvent for dissolving or dispersing the 8 th and 9 th polyamic acid compounds, the organic solvent for dissolving or dispersing the 1 st and 2 nd polyamic acid compounds as described above can be used.

In some embodiments, the weight ratio of the 8 th polyamic acid compound to the 9 th polyamic acid compound in the varnish for a photo-alignment film is 4: 6-2: 8, preferably 4: 6-3: 7.

the varnish for a photo-alignment film according to claim 4, wherein the 8 th polyamic acid compound (as a polyamic acid ester) having a tetracarboxylic acid ester residue and the 9 th polyamic acid compound as a polyamic acid coexist. In this case, the polyamic acid has a surface energy greater than that of the polyamic acid ester. That is, the polyamic acid has a polarity higher than that of the polyamic acid ester. Therefore, the 8 th polyamic acid compound and the 9 th polyamic acid compound are phase separated.

When the varnish for a photo-alignment film according to claim 4 is applied to a coating target, the 9 th polyamic acid compound has high affinity with the pixel electrode PE, the 2 nd insulating film 12, and the protective layer OC, and therefore the 9 th polyamic acid compound forms a lower layer, and the 8 th polyamic acid compound forms an upper layer, and comes into contact with the liquid crystal layer LC and the seal portion SE.

In the imidization reaction by heating as described above, the imidization ratio is 70% to 90%. Therefore, when the 8 th polyamic acid compound is imidized with the mole percentage of the carboxylic acid ester group included in the tetracarboxylic acid ester residue in the 8 th polyamic acid compound being 100 mole%, the carboxylic acid ester group as an imidized unreacted portion in the imide compound of the 8 th polyamic acid compound remains in the range of 10 to 30 mole%.

Similarly, when the 9 th polyamic acid compound is imidized with the mole percentage of the carboxyl group contained in the tetracarboxylic acid residue in the 9 th polyamic acid compound being 100 mole%, the carboxyl group as the non-imidized part in the imide compound of the 9 th polyamic acid compound remains in the range of 10 mole% to 30 mole%.

As described above, in the photo-alignment film having a two-layer structure formed using the varnish for a photo-alignment film according to claim 4, the imide of the 9 th polyamic acid compound forms a lower layer (on the insulating substrate side) and the imide of the 8 th polyamic acid compound forms an upper layer (on the liquid crystal and sealing substrate sides), respectively.

In some embodiments, the imide compound (polyimide) of the 8 th polyamic acid based compound forming the upper layer has a structural unit (repeating unit) represented by the above formula (11-3).

In some embodiments, the imide compound (polyimide) of the 9 th polyamic acid compound forming the lower layer has a structural unit (repeating unit) represented by the above formula (12).

Therefore, the imide compound of the 8 th polyamic acid compound forming the upper layer has a cyclobutane skeleton, and thus the cyclobutane skeleton is cracked by the photo-alignment treatment, and a property (alignment controllability) of initially aligning the liquid crystal molecules can be imparted.

In addition, the 8 th polyamic acid compound forming the upper layer has a plurality of aromatic rings bonded through the 2 nd linking group, and therefore, phase separation from the 9 th polyamic acid compound is more likely to occur. Therefore, the imide compound of 8 th polyamic acid compound that initially aligns liquid crystal molecules can be easily formed as an upper layer.

Further, the imide compound of 8 th polyamic acid compound forming the upper layer has a plurality of aromatic rings bonded through the 2 nd linking group, and therefore, flexibility can be imparted. Therefore, even if an external force is applied to the liquid crystal display device, the imide compound absorbs the impact due to the external force, and the seal portion and the alignment film are less likely to be peeled off.

In addition, the imide compound of the 8 th polyamic acid compound forming the upper layer is further bonded with a carboxyl group or an amino group directly or via the 3 rd linking group to at least 1 of the plurality of aromatic rings, and the carboxyl group or the amino group is bonded to the sealing portion, so that the imide compound is more firmly bonded to the sealing portion.

Since the carboxyl group remains as an unreacted imidized portion in the imide compound of the 9 th polyamic acid compound forming the lower layer, the carboxyl group is bonded to the 2 nd insulating film, the pixel electrode, and the protective layer. Therefore, the imide compound of the 9 th polyamic acid compound is strongly bonded to these materials.

Therefore, by using the varnish for a photo-alignment film according to claim 4, a photo-alignment film having improved adhesion strength to a sealing portion can be formed without deteriorating performance of initially aligning liquid crystal molecules of a liquid crystal layer.

The varnish for a photo-alignment film according to any one of claims 1 to 4 may contain a silane coupling agent. The silane coupling agent bonds to the pixel electrode PE, the protective layer OC, and the seal portion SE, and contributes to improvement of adhesion to the seal portion SE. The polyamic acid compound contained in the varnish for a photo-alignment film is contained in the varnish for a photo-alignment film in a range of 0.3 to 2.0 parts by weight based on 100 parts by weight of the polyamic acid compound.

When the silane coupling agent is less than 0.3 parts by weight, it may not contribute to improvement of adhesion to the pixel electrode PE, the protective layer OC, and the sealing portion SE.

If the silane coupling agent is more than 2.0 parts by weight, the silane coupling agent may be eluted into the liquid crystal layer, and display defects such as image sticking may occur in the liquid crystal display device.

The silane coupling agent is, for example, an epoxy silane coupling agent or an amine silane coupling agent. The epoxy silane coupling agent can be exemplified as follows.

The amine silane coupling agent can be exemplified as follows.

In the above aspect, the 1 st alignment film AL1 and the 2 nd alignment film AL2 are formed of the varnish for a photo-alignment film of the present invention, but at least one of the 1 st alignment film AL1 and the 2 nd alignment film AL2 may be formed of the varnish for a photo-alignment film of the present invention.

Examples

The present invention will be described below with reference to examples, which first describe examples of synthesis of a polyamic acid compound.

Synthesis example of Polyamic acid Compound

Synthesis example 1

A polyamic acid-based compound precursor having a tetracarboxylic acid residue was produced by mixing a solution of N-methyl-2-pyrrolidone (NMP) in an amount of 100 parts by mole of 2, 5-diaminobenzoic acid as a diamine compound, a solution of NMP in an amount of 100 parts by mole of 1, 3-dimethyl-1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride (CBDA) as a tetracarboxylic acid compound, and butyl cellosolve. To the reaction mixture, 100 parts by mole of N, N-Dimethylformamide (DFA) was added dropwise, and the reaction was carried out at 50 ℃ for 2 hours to methyl-esterify the carboxyl group of the tetracarboxylic acid residue in the precursor. Unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic ester residue.

Synthesis example 2

A polyamic acid-based compound precursor having a tetracarboxylic acid residue was produced by mixing 50 parts by mole of 2, 5-diaminobenzoic acid as a diamine compound, an NMP solution of 4, 4' -ethylenedianiline (ethylenedianiline), an NMP solution of 100 parts by mole of CBDA as a tetracarboxylic acid compound, and butyl cellosolve. To the reaction mixture, 100 parts by mole of DFA was added dropwise, and the reaction was carried out at 50 ℃ for 2 hours to methyl-esterify the carboxyl group of the tetracarboxylic acid residue in the precursor. Unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic ester residue.

Synthesis example 3

A polyamic acid compound precursor having a tetracarboxylic acid residue was produced by mixing a NMP solution containing 100 parts by mole of 1, 2-bis (4-amino-3-carboxyphenyl) ethane as a diamine compound, a NMP solution containing 100 parts by mole of CBDA as a tetracarboxylic acid compound, and butyl cellosolve. To the reaction mixture, 100 parts by mole of DFA was added dropwise, and the reaction was carried out at 50 ℃ for 2 hours to methyl-esterify the carboxyl group of the tetracarboxylic acid residue in the precursor. Unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic ester residue.

Synthesis example 4

A polyamic acid-based compound precursor having a tetracarboxylic acid residue was produced by mixing a solution of 100 parts by mole of p-Phenylenediamine (PDA) as a diamine compound in NMP, a solution of 100 parts by mole of CBDA as a tetracarboxylic acid compound in NMP, and butyl cellosolve. To the reaction mixture, 100 parts by mole of DFA was added dropwise, and the reaction was carried out at 50 ℃ for 2 hours to methyl-esterify the carboxyl group of the tetracarboxylic acid residue in the precursor. Unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic ester residue.

Synthesis example 5

An NMP solution of 100 parts by mole of PDA as a diamine compound, an NMP solution of 100 parts by mole of pyromellitic dianhydride as a tetracarboxylic acid compound, and butyl cellosolve were mixed, and unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid-based compound solution having a solid content of 15 wt% and a desired tetracarboxylic acid residue.

Synthesis example 6

A polyamic acid-based compound precursor having a tetracarboxylic acid residue to which a carboxyl group is bonded is produced by mixing 100 parts by mole of PDA as a diamine compound, 100 parts by mole of CBDA as a tetracarboxylic acid compound, and a butyl cellosolve. To the reaction mixture, 50 parts by mole of DFA was added dropwise, and the reaction was carried out at 50 ℃ for 2 hours to methyl-esterify about half of the carboxyl groups of the tetracarboxylic acid residues in the precursor. Unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic acid residue to which a carboxyl group and a carboxylate group were bonded.

Synthesis example 7

100 parts by mole of NMP solution of PDA as a diamine compound, 100 parts by mole of NMP solution of CBDA as a tetracarboxylic acid compound, and butyl cellosolve were mixed, and unreacted monomers and low-molecular weight components were removed to obtain a polyamic acid compound solution having a solid content of 15 wt% and having a desired tetracarboxylic acid residue.

Synthesis example 8

An NMP solution of 100 parts by mole of 4, 4-diaminodiphenyl ether as a diamine compound, an NMP solution of 100 parts by mole of pyromellitic dianhydride as a tetracarboxylic acid compound, and butyl cellosolve were mixed, and unreacted monomers and low-molecular-weight components were removed to obtain a polyamic acid-based compound solution having a solid content of 15% by weight and having a desired tetracarboxylic acid residue.

Examples 1 to 4

Coating liquids (varnish for photo-alignment film) of examples 1 to 4 were prepared by mixing the upper layer component and the lower layer component shown in table 1 below at a weight ratio of 5: 5.

The coating solutions of examples 1 to 4 were applied to the region of the 1 st substrate SUB1 to be coated with the 1 st alignment film AL1 and the region of the 2 nd substrate SUB2 to be coated with the 2 nd alignment film AL2 of the liquid crystal display device having the structure shown in fig. 2 so that the film thicknesses thereof became 100nm, respectively, and heated at 230 ℃ for 10 minutes to effect imidization. The imidization rate was 80%.

Each of the imidized films was irradiated with polarized ultraviolet light in the 254nm to 365nm region to perform a photo-alignment treatment. In the photo-alignment process, a short arc light source (USH) is usedAn IO INC (manufactured BY "ウシ torch" in Japanese), UXM-5000 BY). The irradiation amount of polarized ultraviolet rays in the photo-alignment treatment was about 1.5J/cm². The irradiation dose was measured by a cumulative illuminometer (UVD-S254 sensor, manufactured by USHIO inc.).

The imidized film after the photo-alignment treatment was heated at 230 ℃ for 30 minutes to form a photo-alignment film. The photoalignment film formed as described above was bonded to the photoalignment film of the other substrate by using the 1 st substrate SUB1 and the 2 nd substrate SUB2, by providing a sealing portion at the periphery of the photoalignment film formed on one substrate, dropping a liquid crystal material and sealing the sealing portion, and then bonding the liquid crystal material to the photoalignment film of the other substrate. The gap between the 1 st substrate SUB1 and the 2 nd substrate SUB2 was set to 3 μm. As the liquid crystal, a negative-type liquid crystal material (Δ n ═ 0.11) was used.

Polarizing plates were bonded to both sides of the produced liquid crystal cell so as to form a crossed nicol cell, and the liquid crystal display device of example 1 was produced by a conventional method. The lighting device uses 10000cm/cm²YAG (yttrium aluminum garnet phosphor) -LED light source. The driving voltage was set to a voltage (2.2V) that was 22% of the maximum luminance, with voltage-luminance characteristics being obtained. Liquid crystal display devices of examples 2 to 4 were manufactured according to the method for manufacturing a liquid crystal display device of example 1.

Using the liquid crystal display devices of examples 1 to 4, a dropping test (evaluation 1) and a sintering test (evaluation 2) were carried out.

< evaluation 1: drop test >

Examples 1 to 4 liquid crystal display devices were prepared in 1 stage, and were dropped in a vertical direction from a height of 2m, and whether or not peeling occurred between the 1 st substrate SUB1 and the 2 nd substrate SUB2 was observed, and adhesiveness of the alignment film, the pixel electrode, the protective layer, and the sealing portion was evaluated in accordance with the following 3-stage.

A: and (4) not peeling.

B: a portion of the peeled portion was observed.

C: and (6) stripping.

< evaluation 2: sintering test >

In order to evaluate the alignment controllability (the performance of initially aligning liquid crystal molecules) of the alignment film, a sintering test was performed.

The liquid crystal display devices of examples 1 to 4 were each provided with a white and black (indicated by oblique lines in the figure) checkerboard pattern shown in fig. 5 for 1 hour at 60 ℃. Each checkered pattern is a square with 5mm on one side. White is the maximum brightness (256/256 gray scale) and black is the minimum brightness (0/256 gray scale). After 1 hour, when a voltage of 1% of the maximum luminance was applied to the entire screen to perform 3/256-gradation gray display on the entire screen, a phenomenon (burning) was observed in which the luminance of the white display portion and the black display portion were different in the 1 hour display. The change rate of the brightness of the two display parts is used as the intensity of the afterimage,

luminance change rate of both display sections:

{(a-b)/b}×100

(in the formula, a is the brightness of the white display part, and b is the brightness of the black display part). When the value is 1% or more, the image can be recognized as a ghost by human eyes.

Whether or not the above checkerboard pattern was burned in the gray display after 1 hour of continuous lighting at 60 ℃ was visually observed, and the alignment controllability (the performance of initially aligning the liquid crystal molecules) of the alignment film was evaluated on the following level 2.

A: in the gray display, sintering was not confirmed. (alignment controllability not degraded)

B: in the gray display, sintering was confirmed. (reduction in orientation controlling ability)

The results are also shown in table 1 below.

TABLE 1

As shown in example 1, it was found that the optical alignment film including the imide compound of the polyamic acid compound (synthesis example 1) having a cyclobutane skeleton and a1 st diamine compound residue as the upper layer component was strongly adhered to the sealing portion, and the performance (alignment controllability) of initial alignment of the liquid crystal molecules was imparted.

As shown in examples 2 and 3, as the upper layer components, the photo-alignment film including the imide of the polyamic acid compound (synthesis example 2) having the cyclobutane skeleton and the 1 st and 2 nd diamine compound residues and the photo-alignment film including the imide of the polyamic acid compound (synthesis example 3) having the cyclobutane skeleton and the 3 rd diamine compound residue were strongly adhered to the sealing portion, and the performance (alignment control ability) of initially aligning the liquid crystal molecules was imparted.

On the other hand, as shown in example 4, it was found that the photo-alignment film including the imide compound of the polyamic acid compound (synthetic example 4) not including any of the 1 st to 3 rd diamine compound residues as the upper layer component was not strongly adhered to the sealing portion.

Examples 5 to 7

The upper layer component and the lower layer component shown in the following table 2 were mixed at a weight ratio of 5: 5 to prepare coating solutions (varnishes for photo-alignment films) of examples 5 to 7. Next, liquid crystal display devices of examples 5 to 7 were produced by the method for producing a liquid crystal display device of example 1 using the coating liquids of examples 5 to 7, respectively.

Next, the liquid crystal display devices of examples 5 to 7 were used to perform the above-described evaluations 1 and 2. The results are also shown in Table 2 below.

TABLE 2

As shown in example 6, it was found that the photo-alignment film including the imide compound of the polyamic acid compound (synthetic example 6) having a cyclobutane skeleton and a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded as the upper layer component was strongly adhered to the sealing portion, and the performance (alignment controllability) of initial alignment of the liquid crystal molecules was imparted.

On the other hand, as shown in example 5, it was found that the photoalignment film including the imide compound of the polyamic acid compound having a cyclobutane skeleton and a tetracarboxylic acid ester residue (synthetic example 4) as the upper layer component did not have a carboxyl group and thus was not strongly adhered to the sealing portion.

As shown in example 7, it was found that in the photo-alignment film of imide having as an upper component a polyamic acid compound having a cyclobutane skeleton and a tetracarboxylic acid residue (synthesis example 7), the polyamic acid compound having a tetracarboxylic acid residue (synthesis example 5) as a lower component was difficult to be separated from the upper component, and it was difficult to impart the performance (alignment controllability) of initial alignment of liquid crystal molecules by photo-alignment treatment.

Examples 8 to 12

The coating liquids (varnish for photo-alignment film) of examples 8 to 12 were prepared by mixing the upper layer component and the lower layer component at the mixing ratios shown in table 3 below. Next, liquid crystal display devices of examples 8 to 12 were produced in the same manner as the liquid crystal display device production method of example 1, using the coating liquids of examples 8 to 12.

Next, the above-described evaluations 1 and 2 were performed using the liquid crystal display devices of examples 8 to 12. The results are also shown in Table 3 below.

TABLE 3

As shown in examples 9 to 11, as the upper layer component, the photo-alignment film of imide of polyamic acid compound including polyamic acid compound having cyclobutane skeleton and tetracarboxylic acid ester residue (synthesis example 4) and polyamic acid compound having cyclobutane skeleton and tetracarboxylic acid residue (synthesis example 7) was firmly adhered to the sealing part and provided with the performance of initial alignment of liquid crystal molecules (alignment control ability) in the range of 25 parts by weight or more and 75 parts by weight or less, when the total amount of polyamic acid compounds of synthesis examples 4 and 7 was taken as 100 parts by weight.

On the other hand, as shown in example 8, it is found that in the photo-alignment film of imide having as an upper component a polyamic acid compound having a cyclobutane skeleton and a tetracarboxylic acid residue (synthesis example 7), the polyamic acid compound having a tetracarboxylic acid residue (synthesis example 8) as a lower component is less likely to be separated from the upper component, and is less likely to be imparted with a performance (alignment controllability) for initial alignment of liquid crystal molecules.

As shown in example 12, it was found that the photoalignment film including the imide compound of the polyamic acid compound having a cyclobutane skeleton and a tetracarboxylic acid ester residue (synthetic example 4) as the upper layer component did not have a carboxyl group and thus was not strongly adhered to the sealing portion.

While some embodiments of the present invention have been described above, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments may be implemented in other various forms, and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. These embodiments and modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Claims

1. A varnish for a photo-alignment film, which contains, in an organic solvent: a1 st polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 2 nd polyamic acid compound as a polyamic acid having a polarity higher than that of the 1 st polyamic acid compound,

the tetracarboxylic acid ester residue has a cyclobutane skeleton,

the diamine compound residue contains a1 st diamine compound residue comprising an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group,

wherein the 1 st diamine compound residue is represented by the following formula (2-1),

in the formula (2-1), L¹Is a single bond or a1 st linking group, R²is-COOH or-N (R)³)₂，R³Are each hydrogen or alkyl, Ar¹The symbol "aromatic ring" denotes a bonding site to a tetracarboxylic acid ester residue.

2. A varnish for a photo-alignment film, which contains, in an organic solvent: a 3 rd polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue to which a carboxyl group and a carboxylate group are bonded; and a 4 th polyamic acid compound as a polyamic acid having a polarity higher than that of the 3 rd polyamic acid compound,

the tetracarboxylic acid residue has a cyclobutane skeleton.

3. A varnish for a photo-alignment film, which contains, in an organic solvent: a 5 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid residue; a 6 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 7 th polyamic acid compound as a polyamic acid having a polarity higher than the 5 th and 6 th polyamic acid compounds,

the tetracarboxylic acid residue and the tetracarboxylic acid ester residue each have a cyclobutane skeleton,

the 5 th polyamic acid compound is contained in a range of 25 parts by weight or more and 75 parts by weight or less, based on 100 parts by weight of the total of the 5 th and 6 th polyamic acid compounds.

4. The varnish for a photoalignment film according to claim 2, wherein the diamine compound residue contains a1 st diamine compound residue containing an aromatic ring to which 2 secondary amino groups are bonded and to which a carboxyl group or an amino group is further bonded directly or via a1 st linking group,

5. The varnish for a photoalignment film according to claim 1, wherein the 1 st linking group is an aliphatic group or an aromatic group.

6. The varnish for a photoalignment film according to claim 1, wherein the diamine compound residue further comprises: a 2 nd diamine compound residue having 2 secondary amino groups and having a plurality of aromatic rings bonded via a 2 nd linking group,

wherein the 2 nd diamine compound residue is represented by the following formula (2-2),

in the formula (2-2), L²Is a 2 nd linking group, Ar⁵And Ar⁶Each is an aromatic ring, and the symbol denotes a bonding site with a tetracarboxylic acid ester residue.

7. The varnish for a photoalignment film according to claim 6, wherein a carboxyl group or an amino group is further bonded to at least 1 of the plurality of aromatic rings of the 2 nd diamine compound residue directly or via a 3 rd linking group.

8. The varnish for a photoalignment film according to claim 1, wherein the diamine compound residue contains: a 3 rd diamine compound residue having 2 secondary amino groups and having a plurality of aromatic rings bonded via a 2 nd linking group,

a carboxyl group or an amino group is further bonded to at least 1 of the plurality of aromatic rings of the 3 rd diamine compound residue directly or through a 3 rd linking group,

wherein the 3 rd diamine compound residue is represented by the following formula (2-3),

in the formula (2-3), L²Is a 2 nd linking group, L³Is a single bond or a 3 rd linking group, Ar⁵And Ar⁶Are each an aromatic ring, R²is-COOH or-N (R)³)₂，R³Hydrogen or alkyl, respectively, and the corresponding symbol indicates the bonding site with the tetracarboxylic acid ester residue.

9. A varnish for a photo-alignment film, which contains, in an organic solvent: a 8 th polyamic acid compound having a diamine compound residue and a tetracarboxylic acid ester residue; and a 9 th polyamic acid compound as a polyamic acid having a polarity higher than that of the 8 th polyamic acid compound,

the tetracarboxylic acid ester residue has a cyclobutane skeleton,

the diamine compound residue contains: a 3 rd diamine compound residue having 2 secondary amino groups and having a plurality of aromatic rings bonded via a 2 nd linking group,

a carboxyl group or an amino group is further bonded to the aromatic ring of the 3 rd diamine compound residue directly or via a 3 rd linking group,

in the formula (2-3), L²Is a 2 nd linking group, L³Is a single bond or a 3 rd linking group, Ar⁵And Ar⁶Are each an aromatic ring, R²is-COOH or-N (R)³)₂，R³Hydrogen or alkyl, respectively, the symbol in the attached text denotes tetracarboxylateThe bonding site of the residue.

10. The varnish for a photo-alignment film according to claim 6, wherein the 2 nd linking group comprises an alkylene group.

11. The varnish for a photoalignment film according to claim 7, wherein the 3 rd linking group is an aliphatic group or an aromatic group.

12. The varnish for a photoalignment film according to claim 1, further comprising a silane coupling agent.

13. The varnish for a photoalignment film according to claim 12, wherein the silane coupling agent is an amine-based silane coupling agent or an epoxy-based silane coupling agent.

14. A liquid crystal display device includes:

a first substrate (1) having a first surface,

a 2 nd substrate disposed to face the 1 st substrate with a gap therebetween,

a frame-shaped sealing part for bonding the 1 st substrate and the 2 nd substrate,

a liquid crystal layer between the 1 st and 2 nd substrates and the sealing part, an

An alignment film located on the 1 st substrate and in contact with the liquid crystal layer and the sealing portion,

the alignment film comprises an imide compound of the varnish for a photo-alignment film described in any one of claims 1 to 13.