JP2007147898A - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent that hardly degrades by rays of high intensity used in a liquid crystal projector or the like even when the agent is exposed to the rays for a long time, and to provide a liquid crystal display element using the liquid crystal aligning agent and hardly causing display irregularity or decrease in a contrast ratio. <P>SOLUTION: The liquid crystal aligning agent contains a polyimide resin prepared by imidizing an aliphatic tetracarboxylic acid dianhydride and an aliphatic diamine or aromatic diamine, the resin showing the transmittance of 80% or more for light in a near UV region at wavelengths of 250 nm to 380 nm in terms of a 1 μm-thick film of the polyimide resin. A liquid crystal display element is manufactured by using the above liquid crystal aligning agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal aligning agent containing a polyimide resin and a liquid crystal display element using the liquid crystal aligning agent, and in particular, is formed using a liquid crystal aligning agent excellent in light resistance and the liquid crystal aligning agent, like a liquid crystal projector. The present invention relates to a reflective or transmissive liquid crystal display device suitable for an apparatus using a light source that generates a high-intensity light beam.

Conventionally, as a method for controlling the alignment of nematic liquid crystal used in liquid crystal display elements, a liquid crystal alignment film made of a polyimide resin is formed into a film to produce a liquid crystal alignment film, and the liquid crystal alignment film is aligned to nematic liquid crystal molecules by rubbing treatment. A method of imparting sex is widely used. In this case, as the liquid crystal aligning agent, a composition containing a polyamic acid solution type or a polyimide solution type obtained by reacting an aromatic diamine as a main component is used (for example, see Patent Documents 1 to 9). .)
Japanese Patent Laid-Open No. 5-27244 ((0009) to (0013)) JP-A-5-43688 ((0012) to (0015)) JP-A-6-82794 ((0012)) JP 7-49501 A ((0009) to (0018)) Japanese Patent Laid-Open No. 8-100061 ((0006)) JP-A-9-176315 ((0010) to (0014)) Japanese Patent Laid-Open No. 11-84391 ((0010) to (0014)) JP 2001-228483 A ((0013) to (0016)) JP 2002-20487 A ((0011) to (0013))

However, when the liquid crystal display element according to the prior art is applied to a liquid crystal projector using a light source that generates a high-intensity light beam, if the display is performed for a long time, the liquid crystal alignment film is deteriorated by light, resulting in non-uniformity. Display unevenness and a decrease in contrast ratio occur.
The present invention has been made under the above-described circumstances, and uses a liquid crystal aligning agent that is not easily deteriorated by light even when exposed to high-intensity light rays such as a liquid crystal projector for a long time, and the liquid crystal aligning agent. An object of the present invention is to provide a liquid crystal display element that is less likely to cause display unevenness and a decrease in contrast ratio.

  In order to solve the above-mentioned problems, the present inventors have conducted research, and the liquid crystal alignment film has been irradiated with high-intensity near-ultraviolet light by downsizing the liquid crystal display device or the like. I came up with the main cause of film degradation.

  Based on the above elucidated results, the present inventors have further studied, and a liquid crystal aligning agent that is not easily deteriorated by light even when exposed to a high intensity light beam such as a liquid crystal projector for a long time, and the liquid crystal aligning agent. In order to produce a liquid crystal display element that does not easily cause display unevenness and a decrease in contrast ratio, the liquid crystal display element allows the light in the near ultraviolet region having a wavelength of 250 nm to 380 nm to pass through without absorbing it. I came up with a completely new configuration.

  That is, if the light transmittance in the near ultraviolet region of the wavelength 250 nm to 380 nm of the liquid crystal alignment film in the liquid crystal display element is 80% or more when the film thickness of the liquid crystal alignment film is converted to 1 μm, The idea is that since the energy of light in the ultraviolet region passes through without being absorbed, deterioration of the liquid crystal alignment film can be suppressed.

That is, the first means for solving the above-described problem is:
A liquid crystal aligning agent containing a polyimide resin that is an imidized product of an aliphatic tetracarboxylic dianhydride and an aliphatic diamine or an aromatic diamine,
The said polyimide resin is a liquid crystal aligning agent characterized by becoming a film | membrane whose transmittance | permeability of light with a wavelength of 250 nm-380 nm is 80% or more when it is set as a film | membrane with a film thickness of 1 micrometer.

The second means is
In order to align the liquid crystal molecules in the liquid crystal composition layer, a liquid crystal composition layer including a liquid crystal composition sandwiched between the pair of substrates, at least one of which is transparent between the pair of substrates, the liquid crystal of the substrate A liquid crystal display element having a liquid crystal alignment film formed on the surface facing the composition layer,
The liquid crystal alignment film is a liquid crystal display element in which the liquid crystal alignment agent described in the first means is formed.

According to the liquid crystal aligning agent described in the first means, a liquid crystal aligning film that transmits 80% or more of light having a wavelength of 250 nm to 380 nm can be obtained.
And the liquid crystal display element as described in the 2nd means using the said liquid crystal aligning film is excellent in light resistance, and is long-life even when irradiated with a high intensity light beam.

(Liquid crystal aligning agent)
The liquid crystal aligning agent according to the present invention is a liquid crystal aligning agent containing a polyimide resin that is an imidized product of an aliphatic tetracarboxylic dianhydride and an aliphatic diamine or an aromatic diamine. When the film has a thickness of 1 μm, the film has a light transmittance of 80% or more at a wavelength of 250 nm to 380 nm. As a result, the liquid crystal alignment film manufactured using the liquid crystal alignment agent passes the light energy in the near-ultraviolet region having the wavelength of 250 nm to 380 nm without absorbing it, so that the deterioration of the liquid crystal alignment film is suppressed. It is what.

  Furthermore, since the liquid crystal alignment film is required to have good printability on the substrate and adhesion to the substrate from the viewpoint of productivity of the liquid crystal display element, the material is an imide ring-containing polymer. A polyimide resin is preferred.

（但し、Ｘは、環状構造、線状構造、環状および線状構造、のいずれかの構造を有する４価の有機脂肪族基であり、Ｙは、環状構造、線状構造、環状および線状構造、のいずれかの構造を有する２価の有機基を示す。）の繰り返し単位を有している。当該イミド環含有ポリマは、加熱した有機溶媒中において、テトラカルボン酸二無水物とジアミンとを反応させることにより、直接イミド化したものである。本発明に係るポリイミド樹脂は、上記（１）式の繰り返し単位におけるＸおよびＹの総数において、芳香族基の占める重量が、全重量の２０％以下であることが望ましい。 (Polyimide resin)
First, the polyimide resin used in the present invention will be described.
The polyimide resin according to the present invention is an imide ring-containing polymer having the following general formula (1),

(However, X is a tetravalent organic aliphatic group having any one of a cyclic structure, a linear structure, a cyclic structure and a linear structure, and Y is a cyclic structure, a linear structure, a cyclic structure and a linear structure. A divalent organic group having any one of the following structures :)). The imide ring-containing polymer is directly imidized by reacting tetracarboxylic dianhydride and diamine in a heated organic solvent. In the polyimide resin according to the present invention, the total weight of X and Y in the repeating unit of the above formula (1) is preferably such that the weight occupied by the aromatic group is 20% or less of the total weight.

Here, the tetracarboxylic dianhydride for producing the polyimide resin according to the present invention will be further described.
The tetracarboxylic dianhydride according to the present invention is preferably an aliphatic tetracarboxylic dianhydride, for example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, 3,3 ', 4,4'-dicyclohexyltetracarboxylic dianhydride, bicyclo [2.2.2] -oct-7-ene-2,3,5,6-tetracarboxylic acid An anhydride etc. are mentioned. These tetracarboxylic dianhydrides can be used singly or in combination of two or more.

Next, diamine for producing the polyimide resin according to the present invention will be further described.
The diamine according to the present invention is preferably an aliphatic diamine, for example, hexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,2-cyclohexanediamine, 1,2-diaminotetradecane, 1,2 -Diaminoheptadecane, 1,2-diaminooctadecane, 1,3-cyclohexanediamine, 1,9-diaminononane, 2,2-dimethyl-1,3-propanediamine, 1,11-diaminoundecane, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro- (5,5) undecane 4,4'-diamino-dicyclohexylmethane, 3,3'-dimethyl-4,4'-diamino-dicyclohexyl Examples include methane, 1,4-bis (3-aminopropyl) piperazine, aminopropyl-terminated dimethylsilicone (LowM.W.), aminopropyl-terminated dimethylsilicone (HighM.W.), And the like. These diamines can be used alone or in combination of two or more.

  Furthermore, aromatic diamines can also be used as diamines according to the present invention, such as p-phenylenediamine, 3,3′-dimethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4. '-Diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,3-bis- (4- Aminophenoxy) benzene, 1,3-bis- (3-aminophenoxy) benzene, 4,4'-diaminodiphenylsulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, 2,2'-bis {4 -(4-Aminophenoxy) phenyl} propane, 2-dodecyloxy-1,4-diaminobenzene, 2,2'-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 4,4'-diamino Examples include benzanilide. These aromatic diamines can be used alone or in combination of two or more, and further in combination with the aliphatic diamine described above.

(Manufacture of polyimide resin)
The polyimide resin according to the present invention can be produced by dissolving an aliphatic tetracarboxylic dianhydride and a diamine in a heated organic solvent and imidizing directly. The mixing ratio of the aliphatic tetracarboxylic dianhydride and the diamine is preferably 1: 1 (molar ratio).
Here, examples of the organic solvent include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, sulfolane, anisole, dioxolane, butyl cellosolve acetate, and lactone. These organic solvents can be used alone or in combination of two or more.

  The above mixture was stirred in a nitrogen atmosphere, then heated to 180 ° C. and stirred for 5 hours to directly imidize to obtain a polyimide solution. The precipitate produced by putting the obtained polyimide solution into a poor solvent such as methanol was pulverized, filtered, washed and dried to obtain a polyimide resin soluble in an organic solvent.

(Manufacture of liquid crystal aligning agent)
A liquid crystal aligning agent can be obtained by diluting the produced soluble polyimide resin with an organic solvent. For the liquid crystal alignment film agent, γ-aminopropyltriethoxysilane, δ-aminopropylmethyldiethoxysilane, N-β (aminoethyl) is optionally used in order to improve adhesion to the substrate and film strength. Amino silane coupling agents such as γ-aminopropyltrimethoxysilane, epoxy silane coupling agents, titanate coupling agents, surface treatment agents such as aluminum alcoholates, aluminum chelates, zirconium chelates, acrylic resins, epoxy resins It is also a preferred configuration that is added alone or in admixture of two or more.
The solid content concentration in the liquid crystal aligning agent is not particularly specified, but is preferably in the range of 1 to 10 wt%.

(Liquid crystal alignment film formation)
The liquid crystal alignment film can be formed by applying the liquid crystal alignment agent according to the present invention to a predetermined substrate. The substrate is a pair of substrates at least one of which is transparent, and a liquid crystal composition layer containing a liquid crystal composition described later is sandwiched between the pair of substrates, and is formed on the surface of the substrate facing the liquid crystal composition layer. The liquid crystal molecules in the liquid crystal composition layer are aligned by the liquid crystal alignment film.
As a coating method, a general spin coating method, printing method, dipping method, brush coating, roll coater method, spray method, or the like can be applied.

(Liquid crystal composition)
Examples of liquid crystals include 4-substituted phenyl-4′-substituted cyclohexane, 4-substituted cyclohexyl-4′-substituted cyclohexane, 4-substituted phenyl-4′-substituted dicyclohexane, and 4-substituted dicyclohexyl-4′-substituted diphenyl. 4-substituted-4'-substituted terphenyl, 4-substituted biphenyl-4'-substituted cyclohexane, 2- (4-substituted phenyl) -5-pyrimidine, 2- (4-substituted dioxane) -5-phenyl, 4 -Substituted benzoic acid-4'-phenyl ester, 4-substituted cyclohexanecarboxylic acid-4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid-4'-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid Acid-4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid- '-Substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid-4'-substituted cyclohexyl ester, 4-substituted-4'-substituted biphenyl, 4-substituted cyclohexyl luo 4'-substituted phenyldioxane, 4-substituted cyclohexyl -4'-substituted phenylpyrimidine and the like. Among these compounds, an alkyl group, an alkoxy group, an alkoxymethylene group, a cyano group, a fluorine group, a difluorine group, or a trifluorine group is present at least at one end of the molecule. A multi-component mixed liquid crystal composition is preferably used.

(Manufacture of liquid crystal display elements)
As described above, the reflective liquid crystal display element and the transmissive liquid crystal display element can be manufactured by sandwiching the liquid crystal composition between the substrates on which the liquid crystal alignment film described above is formed by a known method.

(Liquid crystal projector using a reflective liquid crystal display element)
An example of a liquid crystal projector to which the reflective liquid crystal display element according to the present invention is applied will be described with reference to FIG. Here, FIG. 1 is a conceptual sectional view of an example of a liquid crystal projector to which the reflective liquid crystal display element according to the present invention is applied.
In FIG. 1, a MOS (Metal Oxide Semiconductor) transistor 2, a reflective pixel electrode 4 that also serves as a reflector, a signal wiring that drives the MOS transistor 2, and a reflective pixel are disposed independently on a single crystal silicon substrate 1. An active matrix substrate 12 composed of a wiring layer 3 composed of wiring for electrically connecting the electrode 4 and the MOS transistor 2, a dielectric film 5 as a protective film, and a liquid crystal alignment film 6 according to the present invention, A liquid crystal alignment film 9 including the alignment agent and a counter glass substrate 13 composed of a glass substrate 11 having a transparent electrode 10 are arranged to face each other, and a liquid crystal layer 8 is sandwiched therebetween to constitute a cell. The liquid crystal layer 8 is uniformly maintained in thickness by a columnar spacer 7 disposed between the active matrix substrate 12 and the counter glass substrate 13. In addition, the phase plate 14 and a polarizing beam splitter 15 serving as a polarizer and an analyzer are provided.

  The reflective active matrix substrate 12 uses a MOS transistor 2 as an active element for driving liquid crystal on a single crystal silicon substrate 1, and a source diffusion layer, a source electrode, and a drain diffusion layer on a silicon substrate and a p-type wafer. The MOS transistor 2 is formed from a drain electrode, a polysilicon gate, and the like. A spin-on-glass insulating layer is provided for interlayer insulation. Examples of the material of the reflective pixel electrode 4 include metals having good reflectivity in the visible light region, such as aluminum or silver. If the reflective pixel electrode 4 is formed on a flat surface, a stable film can be formed and good reflective characteristics can be obtained. Therefore, an insulating layer provided as a base of the reflective pixel electrode 4 is It is desirable that the surface be polished and flattened.

(Liquid crystal projector using transmissive liquid crystal display elements)
An example of a liquid crystal projector to which the transmissive liquid crystal display element according to the present invention is applied will be described with reference to FIGS. Here, FIG. 2 is a conceptual cross-sectional view of an example of a two-lamp three-plate liquid crystal projector to which the transmissive liquid crystal display element according to the present invention is applied, and FIG. It is a notional sectional view of a liquid crystal light valve portion of.

  In FIG. 2, the illumination device 21 includes two light sources 21A and 21B arranged side by side. The light emitting unit 22 in each light source is composed of an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp or the like, and the irradiation light is emitted as parallel light by the parabolic reflector 23 and guided to the integrator lens 24. The integrator lens 24 is composed of a pair of lens groups. In the figure, the left half guides the light emitted from the light source 21A to the front surface of the liquid crystal light valve, and the right half transmits the light emitted from the light source 21B to the liquid crystal light valve. Will lead to the front. The light that has passed through the integrator lens 24 is guided to the first dichroic mirror 27 (27A, 27B) after passing through the polarization conversion device 25 and the condenser lens 26.

  The polarization conversion device 25 is configured by a plurality of polarization beam splitter arrays (hereinafter may be referred to as “PBS arrays”). The PBS array includes a polarization separation film and a phase difference plate (1 / 2λ plate) (both not shown). Of the light from the integrator lens 23, for example, the polarization separation film passes P-polarized light, and the S-polarized light is reflected and emitted by changing the optical path by 90 °. The P-polarized light that has passed through the PBS array is converted to S-polarized light by a phase difference plate provided on the front side (light emission side) and emitted. That is, almost all light is converted to S-polarized light.

  The first dichroic mirror 27 passes light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The first dichroic mirror 27 includes a first divided portion 27A and a second divided portion 27B. The light in the red wavelength band that has passed through the first dichroic mirror 27 passes through the concave lens 28 and is reflected by the reflection mirror 29 to change the optical path. The red light reflected by the reflection mirror 29 passes through a lens 30 and passes through a transmissive liquid crystal light valve 31 for red light, and is modulated. On the other hand, the light in the cyan wavelength band reflected by the first dichroic mirror 27 is guided to the second dichroic mirror 35 through the concave lens 34.

  The second dichroic mirror 35 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 35 is guided to the transmissive liquid crystal light valve 32 for green light through the lens 36 and is modulated by being transmitted therethrough. The blue wavelength band light transmitted through the second dichroic mirror 35 passes through the relay lens 37, the total reflection mirror 38, the relay lens 39, the reflection mirror 40, and the relay lens 41, and is a transmissive liquid crystal light valve 33 for blue light. The light is modulated by being transmitted through this.

  Here, each of the liquid crystal light valves 31, 32, 33 includes panel portions 31b, 32b, 33b formed by enclosing liquid crystals between the incident side polarizing plates 31a, 32a, 33a and a pair of glass substrates, and the outgoing side polarizing plate 31c. , 32c, 33c. (Details of the structure of each of the liquid crystal light valves 31, 32, and 33 will be described later with reference to FIG. 3.) The modulated light (each color image light) modulated through the liquid crystal light valves 31, 32, and 33 is Are combined by the dichroic prism 41 to become color image light. The color image light is enlarged and projected by the projection lens 42 and is projected and displayed on the screen 43.

  Here, the details of the structure of each of the liquid crystal light valves 31, 32, 33 will be described with reference to FIG. 3. However, since each of the liquid crystal light valves 31, 32, 33 has the same structure, the liquid crystal light valves 31, 32, 33 have the same structure. The light valve 31 will be described as a representative example.

  In FIG. 3, the liquid crystal light valve 31 includes, in order from the light incident side, an incident side polarizing plate 31a, a panel portion 31b, and an output side polarizing plate 31c. Further, the panel unit 31b includes a transparent electrode substrate 60, an active element substrate 70, transparent glass substrates 61 and 67, a transparent electrode 62, liquid crystal alignment films 63 and 73 including an alignment agent according to the present invention, a liquid crystal 51 to which no voltage is applied, a voltage Is applied to the liquid crystal 52, the transparent pixel electrode 74, and the active drive element 72.

  The liquid crystal light valve 31 has a configuration in which liquid crystals 51 and 52 are sandwiched between a transparent electrode substrate 60 and an active element substrate 70. The transparent electrode substrate 60 is formed by laminating a transparent electrode 62 and a liquid crystal alignment film 63 containing an alignment agent according to the present invention for uniformly aligning liquid crystal molecules on the surface of a glass substrate 61. On the other hand, the active drive element 70 has an active drive element 72 such as a thin film transistor (TFT), a transparent pixel electrode 74 for applying a voltage from the active drive element 72 to the liquid crystals 51 and 52, and a book on the surface of the glass substrate 71. A liquid crystal alignment film 73 containing the alignment agent according to the invention is laminated.

  The transparent pixel electrodes 74 are arranged in a matrix of M pieces in the horizontal direction and N pieces in the vertical direction on the surface of the transparent glass substrate 71. The values of M and N are, for example, VGA (Visual Gate Array (Visual Gate Array). Array)), they are 640 and 480, respectively.

  The transparent electrode 62 and the transparent pixel electrode 74 are made of a film generally called ITO (indium tin oxide, Nesa).

  Further, as the liquid crystals 51 and 52, twisted nematic liquid crystal used in current general TFT-LCDs can be used.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

Example 1
A 300 ml separable four-necked flask equipped with a stirrer is fitted with a ball condenser equipped with a trap with a silicon cock, and 1,2,3,4-cyclopentanetetracarboxylic dianhydride (hereinafter referred to as “CPDA”). 6.30 g, 4,4′-diamino-dicyclohexylmethane (hereinafter sometimes referred to as “DAHM”) 6.31 g, N-methyl-2-pyrrolidone (hereinafter referred to as “ NMP ”may be described.) 50 g and 20 g of toluene were added, and the mixture was stirred at room temperature in a nitrogen atmosphere for 10 minutes, then heated to 180 ° C., stirred for about 5 hours, directly imidized, and weight average molecular weight A 48,000 polyimide solution was obtained. A precipitate formed by putting the obtained polyimide solution into methanol was pulverized, filtered, washed, and dried under reduced pressure to obtain a polyimide resin powder.

  Next, NMP and butyl cellosolve acetate were added to the polyimide resin powder, adjusted to a polyimide solution with a solid content concentration of 5% by weight, and then filtered through a filter having a pore diameter of 1 μm to prepare a liquid crystal aligning agent. The prepared liquid crystal aligning agent is applied to a counter glass substrate, a reflective substrate, and a transparent substrate using a spinner apparatus, temporarily dried at 80 ° C. for 5 minutes, and then heated at 220 ° C. for 30 minutes to completely remove the solvent. Volatilization was performed to form a liquid crystal alignment film having a thickness of 500 mm (angstrom). Between the counter glass substrate on which the liquid crystal alignment film is formed and the reflective substrate on which the liquid crystal alignment film is formed, and between the counter glass substrate on which the liquid crystal alignment film is formed and the transparent substrate on which the liquid crystal alignment film is formed Then, a nematic liquid crystal and a spacer material were encapsulated to produce a reflective liquid crystal display element and a transmissive liquid crystal display element.

(Example 2)
Using the same apparatus as in Example 1, 6.30 g of CPDA, 7.15 g of 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane (hereinafter sometimes referred to as “DMHM”), 50 g of NMP, After adding 20 g of toluene and stirring in a nitrogen atmosphere at room temperature for 10 minutes, the temperature was raised to 180 ° C. and stirred for about 5 hours to obtain a directly imidized polyimide solution having a weight average molecular weight of 53,000. In the same manner as in Example 1, the obtained polyimide solution was poured into methanol, and the precipitate produced by pulverizing, filtering, washing and drying under reduced pressure was obtained to obtain a polyimide resin powder.

  Next, using the polyimide resin powder, the same operation as in Example 1 was performed to produce a reflective liquid crystal display element and a transmissive liquid crystal display element, respectively.

(Example 3)
Using the same apparatus as in Example 1, CPDA 6.30 g, DAHM 5.04 g, p-phenylenediamine (hereinafter sometimes referred to as “PPD”) 0.65 g, NMP 45 g, toluene 20 g were added, room temperature, nitrogen After stirring in the atmosphere for 10 minutes, the temperature was raised to 180 ° C. and stirred for about 8 hours to obtain a polyimide solution having a weight average molecular weight of 55,000 that was directly imidized. In the same manner as in Example 1, the obtained polyimide solution was poured into methanol, and the precipitate produced by pulverizing, filtering, washing and drying under reduced pressure was obtained to obtain a polyimide resin powder.

  Next, using the polyimide resin powder, the same operation as in Example 1 was performed to produce a reflective liquid crystal display element and a transmissive liquid crystal display element, respectively.

Example 4
Using the same apparatus as in Example 1, 6.30 g of CPDA, 2.52 g of DAHM, 0.97 g of PPD, 1.05 g of hexamethylenediamine, 45 g of NMP, and 20 g of toluene were added, and the mixture was stirred at room temperature for 10 minutes in a nitrogen atmosphere. The mixture was heated to 1 hour and stirred for about 12 hours to obtain a directly imidized polyimide solution having a weight average molecular weight of 65,000. In the same manner as in Example 1, the obtained polyimide solution was poured into methanol, and the precipitate produced by pulverizing, filtering, washing and drying under reduced pressure was obtained to obtain a polyimide resin powder.

  Next, using the polyimide resin powder, the same operation as in Example 1 was performed to produce a reflective liquid crystal display element and a transmissive liquid crystal display element, respectively.

(Comparative Example 1)
Using the same apparatus as in Example 1, 12.41 g of 4,4′-oxydiphthalic dianhydride, 6.09 g of 3,5-diaminobenzoic acid, 68 g of NMP, and 20 g of toluene were added, and at room temperature for 10 minutes in a nitrogen atmosphere. After stirring, the temperature was raised to 180 ° C., and the mixture was stirred for about 8 hours to obtain a directly imidized polyimide solution having a weight average molecular weight of 45,000. In the same manner as in Example 1, the obtained polyimide solution was poured into methanol, and the precipitate produced by pulverizing, filtering, washing and drying under reduced pressure was obtained to obtain a polyimide resin powder.

  Next, using the polyimide resin powder, the same operation as in Example 1 was performed to produce a reflective liquid crystal display element and a transmissive liquid crystal display element, respectively.

(Comparative Example 2)
Using the same apparatus as in Example 1, 6.54 g of pyromellitic dianhydride, 0.74 g of 4,4′-diaminodiphenylsulfone, 6.44 g of DMHM, 50 g of NMP, and 20 g of toluene were added, and 10% in a nitrogen atmosphere at room temperature. After stirring for minutes, the temperature was raised to 180 ° C. and stirred for about 5 hours to obtain a directly imidized polyimide solution having a weight average molecular weight of 65,000. In the same manner as in Example 1, the obtained polyimide solution was poured into methanol, and the precipitate produced by pulverizing, filtering, washing and drying under reduced pressure was obtained to obtain a polyimide resin powder.

  Next, using the polyimide resin powder, the same operation as in Example 1 was performed to produce a reflective liquid crystal display element and a transmissive liquid crystal display element, respectively.

(Evaluation of Examples 1 to 4 and Comparative Examples 1 and 2)
1. Measurement of light transmittance On a glass substrate, the polyimide solution having a solid content concentration of 15% produced in Examples 1 to 4 and Comparative Examples 1 and 2 was applied by spin coating, and then temporarily dried at 80 ° C. and 220 ° C. Was dried for 30 minutes to form a polyimide resin film having a thickness of about 1 μm, which was used as a sample for evaluating light transmittance. With respect to each of the samples for light transmittance evaluation, the transmittance of light with wavelengths of 280 nm and 300 nm was measured using a UV-visible spectrophotometer, and the results are shown in Table 1. However, when the transmittance of each wavelength region of the polyimide resin film was 80% or more, it was determined that the transmittance of the polyimide resin film was good.

From the results shown in Table 1, the polyimide resin films according to Examples 1 to 4 both show 85% or more in the transmittance of light with wavelengths of 280 nm and 300 nm, and the transmittance of near ultraviolet light of the polyimide resin film Was found to be good. On the other hand, the polyimide resin films according to Comparative Examples 1 and 2 both showed 70% or less, and the polyimide resin film was found to have low near-ultraviolet light transmittance.
In the visible light region, the transmittance of the polyimide resin film was all 90% or more.

2. Light Resistance / Lifetime Evaluation In the reflective liquid crystal display elements and the transmissive liquid crystal display elements manufactured in Examples 1 to 4 and Comparative Examples 1 and 2, the contrast ratio, which is the ratio of the transmittance between the on state and the off state, is 500: It was confirmed that there was 1 or more, and this was taken as the initial value.
Next, each liquid crystal display element was irradiated with energy light having an output of 5 W / cm ² for 500 hours. And the presence or absence of the change of the said contrast ratio was measured, and the result was described in Table 1. However, when the contrast ratio hardly decreased with respect to the initial value of 500: 1, it was determined that the light resistance was good.

From the results shown in Table 1, the reflective liquid crystal display elements and transmissive liquid crystal display elements according to Examples 1 to 4 have a contrast ratio of 500 even after irradiation with energy light with an output of 5 W / cm ² for 500 hours. : 1 and was found to have sufficient light resistance and lifetime. As described in “1. Measurement of light transmittance”, this is considered to be an effect caused by the polyimide resin films according to Examples 1 to 4 transmitting 80% or more of near-ultraviolet light. .

On the other hand, in the reflective liquid crystal display element and the transmissive liquid crystal display element according to Comparative Example 1, the polyimide resin film was decomposed after irradiating energy light with an output of 5 W / cm ² for 500 hours, and the contrast ratio was Measurement could not be performed. Furthermore, the reflective liquid crystal display element and the transmissive liquid crystal display element according to Comparative Example 2 have a contrast ratio of 50: 1 and a sufficient light resistance after being irradiated with energy light having an output of 5 W / cm ² for 500 hours. It was found that it has no lifetime. This is because, as described in “1. Measurement of light transmittance”, the polyimide resin film according to Comparative Example 1 only transmits 20% or less of near-ultraviolet light, and the polyimide resin film according to Comparative Example 2 Since only 70% or less of the near ultraviolet light is transmitted, it is considered that the polyimide resin film is deteriorated by the energy of the near ultraviolet light.

1 is a conceptual cross-sectional view of an example of a liquid crystal projector to which a reflective liquid crystal display element according to an embodiment of the present invention is applied. It is a conceptual sectional view of an example of a liquid crystal projector to which a transmission type liquid crystal display element according to another embodiment of the present invention is applied. FIG. 3 is a conceptual cross-sectional view of a liquid crystal light valve portion in the liquid crystal projector according to FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single crystal silicon substrate 2 MOS transistor 3 Wiring layer 4 Reflection pixel electrode 5 Dielectric film 6 Liquid crystal alignment film 7 Columnar spacer 8 Liquid crystal layer 9 Liquid crystal alignment film 10 Transparent electrode 11 Glass substrate 12 Active matrix substrate 13 Opposite glass substrate 14 Phase plate DESCRIPTION OF SYMBOLS 15 Polarization beam splitter 21 Illumination device 21A Light source 21B Light source 22 Light emission part 23 Parabolic reflector 24 Integrator lens 25 Polarization converter 27 First dichroic mirror 27A First division part 27B Second division part 28 Concave lens 29 Reflection mirror 30 Lens 31 Liquid crystal light valve 31a Incident side polarizing plate 31b Panel portion 31c Outgoing side polarizing plate 32 Liquid crystal light valve 32a Incident side polarizing plate 32b Panel portion 32c Outgoing side polarizing plate 33 Liquid crystal light valve 33a Incident side polarizing plate 33b Panel Part 33c Output side polarizing plate 34 Concave lens 35 Second dichroic mirror 36 Lens 37, 39, 41 Relay lens 38 Total reflection mirror 39 Relay lens 40 Reflection mirror 41 Relay lens 42 Dichroic prism 43 Projection lens 43 Screen 51 Liquid crystal 52 Liquid crystal 60 Transparent electrode Substrate 61 Transparent glass substrate 62 Transparent electrode 63 Liquid crystal alignment film 70 Active element substrate 71 Glass substrate 72 Active drive element 73 Liquid crystal alignment film 74 Transparent pixel electrode

Claims (2)

A liquid crystal aligning agent containing a polyimide resin that is an imidized product of an aliphatic tetracarboxylic dianhydride and an aliphatic diamine or an aromatic diamine,
The liquid crystal aligning agent, wherein when the polyimide resin is a film having a thickness of 1 μm, the film has a light transmittance of 80% or more at a wavelength of 250 nm to 380 nm. In order to align the liquid crystal molecules in the liquid crystal composition layer, a liquid crystal composition layer including a liquid crystal composition sandwiched between the pair of substrates, at least one of which is transparent between the pair of substrates, the liquid crystal of the substrate A liquid crystal display element having a liquid crystal alignment film formed on the surface facing the composition layer,
The liquid crystal alignment element according to claim 1, wherein the liquid crystal alignment agent according to claim 1 is formed.

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