JPS5949562B2 - liquid crystal display element - Google Patents

Description

[Detailed description of the invention] The present invention relates to a liquid crystal display element.

Conventionally, liquid crystal cells, especially nematic ivy liquid crystal display elements that utilize electro-optical effects that operate under the action of an electric field,
Inorganic materials such as SiO vapor deposited films have been mainly used as alignment films.

The reason for this is that these inorganic films do not dissolve in liquid crystals even when they come into contact with liquid crystals, so they do not have any negative effects, and even if glass frit sealing is performed, Schiff-type liquid crystals and biphenyl-type liquid crystals can be aligned uniformly. This is because there are advantages. On the other hand, liquid crystal display elements have already been proposed in which various organic polymeric materials are used for alignment films, and after alignment treatment is performed by rubbing in one direction with a cloth or the like, the rubbing directions are orthogonal to each other.

For example, natural polyvinyl alcohol, polyester, silicone resin, urea resin, melamine resin, phenolic resin, epoxy resin, alkyd resin, urethane resin, resorcinol resin, furan resin, polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, polystyrene, polyvinyl butyrate, polysulfone, polyamide,
Polyesterimide, polyamideimide, polycarbonate, polyacetal, polyethylene, cellulose resin, natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polybutadiene, polyisoprene, mercapto silane coupling agent, epoxy silane coupling agent, amino Examples include silane coupling agents, viscose rayon, poly-methyl-α-cyanoacrylate, and the like. However, such polymer membranes
The uniformity of liquid crystal alignment is not sufficient, and due to long-term energization tests and deterioration tests, alignment non-uniformity tends to increase compared to inorganic insulating films, resulting in considerable damage to individual liquid crystal display elements. There is a drawback that variations occur. In addition, the glass frit seal is heated to approximately 350°C to 400°C,
Since the heat resistance is insufficient, the alignment film is destroyed and the liquid crystal is not aligned. Next, as another heat-resistant polymer material used for orientation, polyimide (Japanese Patent Application Laid-open No.
65960).

Compared to the aforementioned polymers with low heat resistance, such polymers have considerably better alignment uniformity and durability in long-term current tests and deterioration tests when an organic seal is used. . However, these organic polymers, such as general polyimide polymers represented by the general formula, turn very brown when glass frit-sealed at 350°C to 400°C, and when liquid crystals are encapsulated. It was revealed that the transmittance in dark field was significantly lower than that of SiO vapor-deposited film, and the display quality function was not satisfied.

In addition, polyamic acid, which is a precursor of polyimide, is coated on a liquid crystal substrate and used as an alignment film, but it has the disadvantage of very poor adhesion to the substrate and easy moisture penetration. . Therefore, if only a polyimide polymer five-body alignment film is used, the alignment film will peel off, causing poor alignment. Furthermore, when an organic seal is applied, moisture that has entered the liquid crystal element through the seal collects on the surface of the glass substrate and adheres in the form of fine water droplets. This reduces the peripheral creeping resistance R of the segment electrodes, causing leakage current to flow during lighting.
There was a problem in that the area around the electrodes became electrode-like, causing blurring of characters and the like. An object of the present invention is to obtain a liquid crystal display element having excellent alignment properties and excellent adhesion to substrates.

The liquid crystal display element of the present invention is characterized in that the liquid crystal alignment film is made of a polyimide isoindoloquinazolinedione-siloxane copolymer having isoindoloquinazolinedione and siloxane bonds. The inventors of the present invention have conducted extensive research in consideration of the above circumstances, and have found that using either the organic seal or the glass frit seal does not result in brownish discoloration, a decrease in creepage resistance, or the occurrence of bleeding. However, by forming an alignment film with high transmittance and excellent liquid crystal alignment, the inventors succeeded in providing a liquid crystal display element of excellent quality. That is, in the liquid crystal display element of the present invention, the liquid crystal alignment film has, for example, the following general formula and (where Ar1 is an organic residue of tetracarboxylic acid, Ar2 is a divalent organic group such as an alkylenearylene group, is -0- or -O-Si-《 》一苧1-0-, and R is an alkyl group or an aryl group) from a polyimie isoindoquinazolinedione-siloxane polymer containing a unit structure respectively represented by In fact, this is its characteristic.

The polyimide isoindolozolinedione-siloxane copolymer used in the present invention includes tetracarboxylic dianhydride,
The diaminomonocarbonamide and the diamine compound can be synthesized by reacting at least a diaminosiloxane compound in the presence of a solvent. and,
Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride and 3,3',4,47-benzophenonetetracarboxylic dianhydride, and examples of the diaminomonocarbonamide include 4,4! -diaminodiphenyl ether-3-
NOJ Rubonamide is used. Further, the diaminosiloxane compounds include compounds represented by the group of the following formulas. Two or more types of each component compound may be used.

Next, as the organic solvent, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, etc. can be used.

The ratio of the diaminomonocarbonamide compound to the diaminosiloxane compound may be selected from the range of 95 to 50 mol% for the former and 5 to 50 mol% for the latter. The optimum ratio of the mixture of the diaminomonocarbonamide compound and the diaminosiloxane compound to the tetracarboxylic dianhydride is equimolar. When the present invention is practiced, a more excellent device can be obtained if it is practiced on a substrate in which an inorganic insulating film is provided on the lower layer of the electrode layer or the soil layer. This is based on the experimental result that the copolymer resin film on a film such as SiO2 has a comparatively smaller loss on heating than the copolymer resin film on a glass substrate. Insulating films that exhibit such effects include S102, Al203, TiO2, and the like. When forming the alignment film used in the present invention, there is no need for special consideration in handling the polymer solution;
Performed by spin coating, printing, or other conventional means,
After the film has hardened, rub it with cloth, gauze, etc. As a result, a liquid crystal display element can be formed by performing frit sealing at 38'C. As is well known, in a liquid crystal display element, it is necessary to expose the terminal portions at the periphery of the two substrates and connect them to an external conductor, but the present invention also uses the commonly used means for etching the terminal portions of the alignment film. For example, this can be carried out by printing a mask resist on the terminal portion and removing it after forming the polymer resin film, or by using oxygen plasma.

The liquid crystal compound sealed in the display element of the present invention includes (1
) Schiff-type liquid crystal (for example, a mixture of), (2) biphenyl-type liquid crystal (for example, a mixture), (3) ester-type liquid crystal (for example, a mixture), (4) cyclohexane-type liquid crystal (for example, a mixture of), etc. can be used. can.

All are mixtures of two or more components. According to the invention,
Even when frit-sealed, the liquid crystal does not turn brown when sealed, has excellent transmittance, and due to improved adhesion to the substrate, the alignment film does not peel off, and the liquid crystal exhibits excellent alignment properties. Device fabrication is possible.

Further, even when organic sealing is performed, a decrease in creeping resistance is prevented, and no occurrence of "I kink" is observed. Example 1 4,4'-diaminodiphenyl ether-3-carbonamide (95 mol%) and the compound represented by the general formula (5 mol%) 3,3',4,4L benzophenonetetracarboxylic dianhydride (100 mol %) and N-methyl-Z-pyrrolidone were placed in a flask and stirred at 15-20°C for 5 hours.

A 15% copolymer solution with a viscosity of 25,000 cp at 25°C was obtained.

After diluting this solution to 3%, an inorganic film of SiO2 was formed in advance to a thickness of 1,000λ, a transparent electrode mainly composed of In203 was formed, and a substrate with a mask material printed on the terminal part was rotated. The polymer solution was applied by coating. After removing the mask material, ring closure was performed by heating at 250° C. for 1 hour to form an alignment film of polyimidoisoindoquinazolinedione-siloxane copolymer resin with a thickness of 800λ. After that, rub it in a certain direction with a cotton cloth to remove any debris around the board. Print the spritze, combine the two substrates, and heat it at 380°C.
An element was formed by firing for 0 minutes. Liquid crystals shown in the table were separately injected into these devices, and then each injection port was sealed with epoxy resin to produce a liquid crystal device. These elements. The transmittance was examined using a spectrometer. Further, after the device was left in an atmosphere of 70° C. and 95% RH for 100 hours, it was turned on and examined for the presence or absence of “bleeding”. The results are shown in the table, and it was possible to produce a display element with improved transmittance, almost no decrease in creeping resistance, and no "bleeding". Example 2 4,4'-diaminodiphenyl ether-3-carbonamide (50 mol%) and a compound represented by the general formula (50 mol%)
mol%) and pyromellitic dianhydride (50 mol%), 3
,3',4,4'-benzophenonetetracarboxylic dianhydride (50 mol%) was reacted in N,N-dimethylacetamide at 15°C for 6 hours to obtain a viscosity of 200°C at 25°C.
15 of 00cp. % copolymer solution was obtained.

This solution was diluted to 4%, a mask material was printed on the terminal part of the In203 transparent electrode, and the polymer solution was applied by spin coating.
After removing the mask material, ring-closing was performed by heating at 280° C. to form an alignment film having a thickness of 1,200 wafers having a polyimide-isoindoroquinazolinedione-siloxane copolymer resin. Hereinafter, an element was created in the same manner as in Example 1, and the transmittance and creeping resistance were measured.

The results are shown in the table above. Example 34,4'-diaminodiphenyl ether-3-carbonamide (80 mol%)
A compound represented by the general formula (20 mol%) and pyromellitic dianhydride (100 mol (: fb) were reacted in N,N-dimethylformamide for 2'C, 7 hours to form 25
A 17% copolymer solution with a viscosity of 18000 cp at °C was obtained.

This solution was diluted to 5%, and an alignment film having a thickness of 1000 mm was formed through the same steps as in Example 1. The results are shown in the table. Example 4 4,4'-diaminodiphenyl ether-3-carbonamide (70 mol%) and a compound represented by the general formula (30
mol%) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (100 mol%) were combined with N-methyl-2
- 2'C in pyrrolidone for 5 hours to obtain a 18% copolymer solution with a viscosity of 25000 cp at 25°C.

This solution was diluted to 3CI), and an alignment film having a thickness of 1200λ was formed through the same steps as in Example 1. Results not shown in table. Example 5 A compound represented by the general formula (40 mol%) such as 4,4'-diaminodiphenyl ether rubonamide (60 mol%) and pyromellitic dianhydride (100 mol%) were dissolved in N,N-dimethylacetamide. The viscosity at 25°C was 2100.
A 15% copolymer solution of 0 cp was obtained.

This solution was diluted to 4%, and an alignment film having a thickness of 800 mm was formed through the same steps as in Example 1. The results are shown in the table. Example 6 Using the copolymer solution of Example 1, organic seal elements were formed in the same manner as in Example 1, and the respective liquid crystals were injected.

The results are shown in the table. Example 7 Using the copolymer solution of Example 3, an organic seal element was formed in the same manner as in Example 3, and each liquid crystal was poured into the element.

The results are shown in the table. Example 8 Using the copolymer solution of Example 5, organic seal elements were formed in the same manner as in Example 5, and the respective liquid crystals were injected.

The results are shown in the table. From the above results, the liquid crystal display element using the polyimide isoindoroquinazoline dione-siloxane copolymer resin of the present invention as an alignment film has the same transmittance as above, has a small creepage resistance drop, and does not cause "bleeding". , extremely excellent display performance.

Comparative example 1 4,4'-diaminodiphenyl ether (100 mol%
), pyromellitic dianhydride (100 mol%) was stirred in N-methyl-2-pyrrolidone and N,N-dimethylacetamide at 20°C for 7 hours, and the viscosity at 25°C was 20,000.
A 15% polymer solution of cp was obtained.

This solution was diluted to 3%, and an inorganic film of SiO2 was diluted to 1000%.
A substrate is formed to have a thickness of λ, and a transparent electrode mainly composed of In203 is formed (a mask material is printed on the terminal part).
The polymer solution was applied by spin coating. After removing the mask material,
The ring was closed by heating at 280° C. for 1 hour to form an alignment film having a thickness of 800λ having a polyimide resin. Thereafter, a rubbing operation was performed in a certain direction to print glass frit around the substrate, and it was baked at 380° C. for 30 minutes to form an element. The results are shown in the table, and the transmittance has decreased. Comparative Example 2 Using the polymer solution of Comparative Example 1, organic seal elements were formed in the same manner as in Comparative Example 1, and the respective liquid crystals were injected.

Claims (1)

[Scope of Claims] 1. A liquid crystal display element having a liquid crystal alignment film on a substrate on which transparent electrodes are formed, wherein the alignment film is made of polyimide having isoindoquinazolinedione and a siloxane bond.
A liquid crystal display element comprising an isoindoroquinazolinedione-siloxane copolymer. 2 In claim 1, the copolymer has the following unit structure (I), (II) (I) ▲ Numerical formula, chemical formula, table, etc. ▼ (II) ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, Ar_1 is an organic residue of tetracarboxylic acid, Ar_2 is a divalent organic group, Q is -O- or ▲ Numerical formula, chemical formula, table, etc.) ▼ R is an alkyl group or an aryl group ) A liquid crystal display element comprising: 3. In Claim 1, the copolymer is obtained by reacting a tetracarboxylic dianhydride, a diaminomonocarbonamide compound, and a diaminosiloxane compound; A liquid crystal display element characterized in that the ratio of the diaminosiloxane compound is selected from the range of 95 to 50 mol% for the former and 5 to 50 mol% for the latter.