JPH01298316A - Substrate for interposing liquid crystal - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal orientation film having high coatability, high adhesion, stable orientation characteristic, and providing a high tilt angle by using an imidized product of a specified polyimide silane precursor as liquid crystal orientation film. CONSTITUTION:A liquid crystal orientation film comprises an aromatic polyim ide having a specified structure obtd. by polymerizing a silane modified polyba sic carboxylic acid component having a specified structure obtd. by allowing previously a part of an org. tetracarboxylic acid anhydride component expressed by the formula I to react with an aminosilane compd. expressed by the formula III, with the residual org. tetracarboxylic acid anhydride component and a diamine expressed by the formula II, and causing ring closure of obtd. polyimide silane precursor in a soln. In the formula II, each R1-R4 is a lower alkyl group, etc.; each R5 and R6 is a methyl group, etc. In the formula III, R7 is a linear methylene group or its branched isomer; X is a hydrolyzable group such as alkoxy group, etc.; Y is an alkyl group, etc. Thus, a liquid crystal orientation film having high coatability, high adhesion, stable orientation characteristic, and high tilt angle is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal sandwiching substrate capable of stably maintaining a high pretilt angle of liquid crystal molecules.

(b) Conventional technology Among liquid crystal display elements, those that utilize the supertwisted birefringence effect are noteworthy because they have superior visual properties such as contrast compared to conventionally known TN type liquid crystal display elements. .

The liquid crystal alignment film used in such an element is required to have the property of maintaining a high pretilt angle so that the alignment of the liquid crystal is not disturbed even when the twist angle of the liquid crystal molecules is increased to 180 degrees or more.

In order to impart such properties, methods have been proposed that use a free oblique evaporation film such as silicon monoxide, and a method that uses a specific polyimide organic polymer film that has fluorine atoms between molecules ( JP-A-62-87939).

(e) Problems to be Solved by the Invention However, since the above-mentioned non-obliquely vapor-deposited film of silicon oxide or the like has selectivity to liquid crystals, it cannot necessarily be said that the alignment of all liquid crystals is good. Further, under high temperature heating conditions when assembling a liquid crystal display element, alignment unevenness occurs, resulting in lower yield and productivity, and it is not possible to satisfy the contrast and visual characteristics required for an alignment control film.

On the other hand, a specific polyimide organic polymer film disclosed in JP-A-62-87939 has low selectivity to liquid crystals and is a good crystal alignment film. The pretilt angle of liquid crystal molecules is also higher than that of a single film.

However, this device has a pretilt angle of 10 degrees or less, and in this case, stability tends to be poor at a pretilt angle of 8 degrees or more.

By the way, in order to improve the image quality of a liquid crystal display element that utilizes the super-twisted birefringence effect, the pretilt angle must be at least 8 degrees, preferably at least 10 degrees, and must be able to be maintained stably, which is still insufficient in terms of characteristics. It is something.

Such instability of the pretilt angle tends to be exacerbated by high-temperature heating treatment or rubbing treatment when forming a polyimide film, and it is particularly difficult to precisely orient liquid crystal over a large area.

In addition, alignment films containing highly polar 7 atoms have problems in coating and adhesion to glass substrates, so for example, noaminosiloxane compounds may be incorporated into the molecule by copolymerization, or silane coupling agents may be added. Although these methods have been adopted, the reality is that it has not yet been possible to provide a liquid crystal alignment film or a liquid crystal display element with high image quality and excellent mass production stability and long-term reliability.

The present invention was made in view of the above-mentioned circumstances, and provides a liquid crystal alignment film that has good coating properties and adhesion, provides stable liquid crystal alignment, and can maintain a stable pretilt angle at a high level without any variation. It is an object of the present invention to provide a liquid crystal sandwiching substrate having high long-term reliability.

(d) Means for Solving the Problems In order to solve the above problems, the inventors of the present invention, as a result of repeated tests and experiments, have previously prepared a part of a specific organic tetracarboxylic acid anhydride component with a specific amide/silane. '8 of the polyimide silane precursor obtained by polymerizing the silane-modified polycarboxylic acid component with a specific structure obtained by reacting with the compound, the remaining organic tetracarboxylic acid anhydride component, and the noamine compound.
The inventors have discovered that the above problems can be solved at once by using an aromatic polyimide compound with a specific structure obtained by ring-closing a liquid as an alignment control film, and have completed the present invention.

That is, the present invention provides a liquid crystal sandwiching substrate in which a liquid crystal alignment film is provided on a substrate on which electrodes are formed, wherein the liquid crystal alignment film is an imidized product of the following polyimide silane precursor.

At least one component selected from organic tetracarboxylic acid anhydrides represented by the following general formula (1); and at least one component selected from noamine compounds represented by the following general formula (II).
When producing a polyimidosilane precursor through a polymerization reaction with a seed component, a portion of the organic tetracarboxylic acid anhydride represented by general 24) above is mixed with an aminosilane compound represented by the following general formula (1) in advance. A polyimide silane obtained by reacting the silane-modified polycarboxylic acid component to a silane-modified polycarboxylic acid component, and polymerizing the silane-modified polycarboxylic acid component with the remaining organic tetracarboxylic acid component with the noamine represented by the general formula (Il'l). precursor.

That is, in the liquid crystal sandwiching substrate of the present invention, a part of the organic tetracarboxylic anhydride component represented by the general formula (N) is replaced with an aminosilane compound represented by the general formula (III) as the liquid crystal aligning film. The silane-modified polycarboxylic acid component with a specific structure obtained by reacting with the above general formula (1
) and the noamine represented by the above general formula (II) are subjected to a polymerization reaction, and the resulting polyimide silane precursor solution is ring-closed to obtain a specific structure. The most distinctive feature is the use of aromatic polyimide.

When a liquid crystal cell is formed using the liquid crystal sandwiching substrate of the present invention, the obtained liquid crystal cell can stably maintain a high pretilt angle of liquid crystal molecules, and can maintain initial high performance for a long period of time. This results in a high-quality SBE type liquid crystal display element that can be maintained over a long period of time.

Hereinafter, first, the polyimide silane precursor used in the present invention will be explained.

The polyimide silane precursor used in the present invention is prepared in advance by
A part of the organic tetracarboxylic acid anhydride component represented by the above general formula (+) is reacted with the ami7 silane compound represented by the above general formula (In) compound, and the hydrogen in the amino group in this ami/silane compound is Hydrolyzable group (X)
to form a silane-modified polycarboxylic acid component represented by the following general formula, and this carboxylic acid component is polymerized with the noamine represented by the above general formula (II) together with the remaining organic tetracarboxylic acid component. It can be manufactured by

In the 7-minosilane-modified portion of the general formula (IV), such a polyimidosilane precursor significantly improves its adhesion or adhesion to various glass plates for liquid crystal cells during the process of conversion to polyimidosilane.

The imidized film thus obtained has the property of stably maintaining the pretilt angle of liquid crystal molecules at 8 degrees or more against heat history and rubbing treatment in subsequent steps.

According to the present invention, if an imide film is obtained through a polyimidosilane precursor compound using a specific 7-minosilane compound shown in formula (III), the same type of carboxylic acid component can be obtained without using the above-mentioned silane compound. Compared to an imide film obtained by reacting approximately equimolar amounts of the noamine component with the noamine component, the pretilt angle can be stably improved within a range of up to about 5 degrees.

Furthermore, in this case, since the adhesion is excellent, it is possible to obtain a liquid crystal sandwiching substrate having excellent long-term reliability without using a noaminosiloxane compound or a silane coupling agent in combination.

By the way, as used in normal polyimide synthesis,
When a carboxylic acid component and a noamine component are subjected to a polycondensation reaction in a substantially equimolar ratio, and an amide 7 silane compound defined by the formula (I[l) of the present invention is post-added to the polyimide precursor solution obtained thereby, Although it is possible to improve the pretilt angle, in order to obtain the same degree of increase as in the present invention, it is necessary to increase the amount added several times or more compared to the present invention.

Furthermore, the polyimide precursor solution containing such a large amount of silane compound mostly in a free state is unstable and deteriorates during storage.
For this reason, it is difficult to obtain an imidized film obtained by pouring this solution with a stable pretilt angle, and the reliability is poor.
In addition, the polyimide base has excellent heat resistance and electrical insulation properties, 8!
The mechanical properties are also inferior.

That is, as in the present invention, only by using a silane-modified polycarboxylic acid component with a specific structure obtained by reacting a part of a specific organic tetracarboxylic anhydride component with a specific 7-minosilane compound in advance. , a high pretilt angle can be stabilized with the minimum amount of silane modification that does not impair the properties of the polyimide main powder, and it also has good coating properties and adhesion, as well as stable liquid crystal alignment.
The crystal holding substrate with high long-term reliability can be obtained by forming a liquid crystal alignment film that can stably maintain a high pretilt angle without variation.

The organic tetracarboxylic anhydride component used in the present invention is represented by the above general formula (+), for example,
Biromelinate anhydride, 3,3',4,4'-nophenyltracarboxylic anhydride, 2,3,3',4'-nophenyltetracarboxylic anhydride, 3,3',4,4' −
Examples include benzophenone tetracarboxylic anhydride. One type of these organic tetracarboxylic acid anhydride components may be used, or instead, two or more types may be used as a mixture.

The silane-modified polycarboxylic acid component represented by the above-mentioned general formula (IV) used in the present invention is a silane-modified polycarboxylic acid component represented by the above-mentioned general formula (III) in which a part of the di-chained organic tetracarboxylic acid anhydride component is replaced with an amide-7 silane represented by the above-mentioned general formula (III). It is modified with a compound.

Typical examples of the above-mentioned 7-minosilane compounds include γ-aminopropyltrimethoxysilane, γ-7minobrovir)ethoxysilane, β-aminopropyltrimethoxysilane, and β-aminobrobyltriethoxysilane. It can be used for many purposes.

The above modification reaction is carried out between seven primary amide groups and at least one hydrolyzable group (X) in the general formula ([1)] and one of the leading tetracarboxylic acid anhydride components represented by the general formula (1). In order to achieve this reaction, amino/
Approximately 2 to 3 moles of the organic tetracarboxylic acid anhydride component are used per mole of the silane compound. This reaction 11 normally proceeds exothermically, but in the presence of a polar solvent such as N-methyl-2-pyrrolidone or N-N'-tunotylacetamide, the reaction vessel is usually cooled using a water bath or the like. The reaction may be carried out by controlling the temperature at 30° C. or lower until the reaction system becomes uniform and transparent.

Specific examples of the 7-ran modified polycarboxylic acid component obtained by such a method include pyromellitic anhydride as the Isotetracarboxylic acid component, and γ-7-propyltrietoquine silane as the aminosilane compound. [NH2C
) I2CH=C1l+ 5i(OC211,),], its structural formula is as follows. Note that in the following structural formula (1), the circle symbol represents each structural part represented by the general formula (iv).

(1 bend j f 1 formula (1) "In the binary structural formula (1), in order to set n = 3, it is sufficient to use approximately 3 moles of pyromellitic anhydride per 1 mole of the ami7 silane compound, and In order to satisfy 11=2, approximately 2 moles of pyromellitic anhydride should be used relative to the amine/silane compound.

And depending on the number of moles of pyromellitic anhydride used, +
In some cases, the composition may be a mixture of 1-2 and n=3, but in the present invention, such a mixed state is acceptable.

`` Uni's explanation is for the case where an aminosilane compound in which Y in the general formula (I[l) is an alkoxy group is used, but the same applies when Y is an acetoxy group. On the other hand, when using an amine/silane compound in which Y is an alkyl group, the number of moles of the organic tetracarboxylic acid component used per mole of the aminosilane compound is approximately 2 moles, and n in the general formula (III) is 2. A silane-modified polycarboxylic acid component must be produced. By leaving at least one alkoxy group or acetoxy group directly bonded to a silicon atom in the modified carboxylic acid component, it is possible to significantly improve the adhesion to glass etc. when made into a polyimide silane polymer. It is from.

Furthermore, the Z structure ii moiety in the general formula (IV) obtained by the exchange reaction as in the above 1st clause contains an X group (C2H, O group in this example) that bonds to the carbonyl carbon.

In this invention, the silane-modified polycarboxylic acid component thus obtained and the remaining unmodified organic tetracarboxylic acid anhydride component [component represented by the above general formula (1)]
A polyimidosilane precursor is produced by simultaneously polymerizing and reacting with a noamine compound represented by general formula (U).

Here, the blending ratio of the acid component and the noamine compound represented by the above general formula (II) is based on the total amount of the silane-modified polyhydric carboxylic acid component and the unmodified organic tetracarboxylic acid anhydride component. Although it is desirable that the amount of the compound be equivalent, it is also possible to set the proportion so that the acid component represented by the above-mentioned total amount is in excess if it is about several mol %.

In addition, the blending ratio of the silane-modified polycarboxylic acid component, which is one of the acid components, is between the amine7amine compound used in the synthesis of this acid component and the organic tetracarboxylic acid represented by the general formula (1) used in the above synthesis. With respect to the total number of moles of the raw materials used consisting of the acid component, the unmodified organic tetracarboxylic acid component, and the noaminated compound represented by the general formula (III), the amount of the Ami-7 silane compound is 0.2 to 20 mol %, Particularly preferably 0.
According to the polyimide silane used in this invention, even if the amount of the amide/silane compound is as small as described above, the pretilt angle of the liquid crystal molecules can be adjusted to about 5 to 7.5 mol%.
It can be stably improved within a range of up to 100%. Furthermore, by optimally setting the usage rate of the amide/silane compound within the above range, the rate of increase in the pretilt angle can be arbitrarily controlled.

However, if the blending ratio of the silane-modified polycarposi acid component is 0
．． If it is less than 2 mol%, the above effect cannot be expected.
On the other hand, if it is more than 20 mol %, it is not desirable because the film properties (external tensile strength and toughness of the polyimide silane film formed as a film) and electrical properties such as dielectric strength voltage may be deteriorated.

Specific examples of the cyamine compound represented by the general formula (n) used in the production of the polyimide precursor used in the present invention include 2,2-biX[4-(4-7minophenoxy)7 enyl]propane, 2,2-bis(4
-(3-7mi/7e/xy)phenyl 1propane, 2.
2-bis[4-(2-aminopheoxy)phenyl 1propane, 2,2-bis[4-(2-amino7eth/xy)
-3,5-methylphenyljpropane, 2,2-bis[4-(,1-7minophenoxy)phenyl1methane,
2,2-bis(4-(4-7minophenoxy)phenyl 1hexafluoropropane, 2,2-bis[4-(3-
aminophexy) phenyl 1 hexafluoropropane, 2,2-bis[4-(2-amino7e7yan)phenyl 1 hexafluoropropane, 212-bis[4-(2
-amino71noquine)-3,5-methylphenyl-1hexafluoropropane, and the like. These cyamine compounds may be used alone or in combination of two or more.

According to the present invention, when applying a polyimide silane precursor to an electrode forming substrate and proceeding with the imide conversion reaction by heating, this reaction can be carried out in a short time, and the resulting polyimide silane film has a low water absorption rate. , and also shows low elasticity.

The polymerization reaction for producing polyimide silane precursor is
It may be carried out according to a conventionally known method, and generally in the presence of an organic solvent, taking into account heat generation during polymerization, a high degree of polymerization is achieved while controlling the temperature to usually 60°C or less, particularly preferably 30°C or less. The reaction should be allowed to proceed until .

Examples of organic solvents include highly polar basics such as N-methyl-2-pyrrolidone, N-N'-tumethylacetamide, N.N'-tumethylformamide, NIN'-tumethylsulfoxide, and hexamethylphosphoformamide. A solvent is used. All of these types of solvents are highly hygroscopic, and absorbed moisture causes a decrease in molecular weight during polymerization and storage stability, so it is recommended to thoroughly dehydrate with a dehydrating agent before use. good. In addition, with these solvents (
General-purpose solvents such as toluene, xylene, benzonitrile, benzene, and phenol can also be used in combination. However, the amount used should be within a range that does not reduce the solubility of the polyimide silane precursor produced.

It is understood that the polyimide silane precursor thus obtained has a structure mainly represented by the following structural formula (2).

That is, it has a structure in which a polymer structural part consisting of an unmodified organic tetracarboxylic acid component and a polymer structural part consisting of a silane-modified polyhydric carboxylic acid component are combined in a predetermined ratio, or the unmodified organic tetracarboxylic acid component It has a polymer structure produced by random polymerization reaction with cyamine, and is characterized by having a /run bond in the molecular chain skeleton of the polyimidosilane precursor. Further, in addition to these polyimide silane precursors, polyimide precursors I:J partially consisting of unmodified organic tetracarboxylic acid units are added.
It is thought that it may be included.

In addition, the following vI structural formula 2) uses pyromellitic anhydride as the organic tetracarboxylic acid component and 2 as the cyamine.
・2-bis[4-(4-7mino7e/quin)phenyl 1
When using propane and the silane-modified polyhydric carboxylic acid component obtained by modifying the above-mentioned tetracarboxylic acid component with a 7-mitsilane compound represented by the above-mentioned structural formula (1) (however, n = 2) This figure shows an example of a polyimide silane precursor.

Structural formula (2)] Liquid crystal sandwiching substrate and r of polyimide silane Iij precursor
- The coating on the r electrode was performed using the above-mentioned organic solvent (). 01
~4()ffl'jt 10 It is applied as a solution to the substrate and the electrode-L by a dip method, a spinner method, a spray method, a printing method, a brush coating method, or the like. After this application temperature 100'C to 400°C1 preferably temperature 2
The polyimide silane precursor is dehydrated and ring-closed by heat treatment at 00'C to 350'Q to obtain an aromatic polyimide silane coating.

This film is subjected to a rubbing treatment to obtain a liquid crystal alignment film.

When a liquid crystal sandwiching substrate in which the polyimide silane film of the present invention is used as an alignment film is used, the pretilt angle of the liquid crystal molecules is a
~15[deg.], and this pretilt angle hardly changed depending on the heat treatment conditions and rubbing conditions during film formation. It also has excellent adhesion to glass substrates and the like, making it possible to maintain a good alignment state reliably over a long period of time.

Therefore, the polyimide silane film in the present invention is suitable for S
It is particularly suitable as a liquid crystal holding substrate used in a BE type liquid crystal display element.

(e) Function The liquid crystal sandwiching substrate of the present invention has the above-mentioned structure, and is modified with a specific structure obtained by reacting a part of a specific organic tetracarboxylic anhydride component with a specific 7-mitsilane compound in advance. Polyhydric carboxylic acid component, residual organic tetracarboxylic anhydride I and noamine are polymerized, and the obtained polyimide silane precursor melt is ring-closed, and an imidized product with a specific structure is formed into an orientation control film. This polyimide silane (precursor is used as a polyimide silane), and in the process of converting it, various types of plastic plates for liquid crystal cells / \ contact (
It has the effect of significantly improving the adhesiveness and adhesion and providing excellent long-term reliability.

1!11 First, as in the present invention, F. a specific structurally modified polyhydric carboxylic acid component obtained by reacting - part of a specific organic tetracarboxylic anhydride component with a specific aminosilane compound. Only by using polyimide, a high pretilt angle can be stabilized with the minimum amount of silane modification that does not impair various properties such as polyimide's original excellent heat resistance, electrical insulation, and mechanical properties. In addition, it has good coating properties and adhesion, provides stable liquid crystal alignment, and has variable pre-tilt angles (liquid crystals with high long-term f? This has the effect of providing a clamping substrate.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

To explain the present invention in detail with reference to the drawings, Fig. 1 is a cross-sectional view of a liquid crystal holding substrate, and (1) is a cross-sectional view of a liquid crystal holding substrate. The substrate (2) is a transparent electrode made of indium oxide, tin oxide, etc.
(3) is an imidized product of a polyimide silane precursor, that is, a polyimide silane film (liquid crystal alignment vc).

The liquid crystal sandwiching substrate of the present invention is manufactured, for example, as follows.

50. Apply the polyimide silane precursor at 0°(
) 1 to 40% by weight solution, preferably 1 to 15% by weight solution was applied and heated at a temperature of 100 = 400'C1, preferably 150 to 350 °C for 5 to 300 minutes ['
! It can be manufactured by forming a polyimide silane film (liquid crystal alignment film) with a thickness of 500 to 2000 people in one ring, and then rubbing the surface of the formed polyimide silane film (liquid crystal alignment film).

Figure 2 shows actual examples of liquid crystal cells obtained using the liquid crystal sandwiching substrate of the present invention, (4) a resin seal made of Epoquin resin, etc., and (5) a ship type liquid crystal, a biphenyl type liquid crystal, and a cyclohexyl type liquid crystal. Liquid crystal Af such as liquid crystal and ester type liquid crystal
It's a waste.

In the following, the measurement of the pretilt angle is carried out using a standard of applied fin chains (Jpn, J, 8pp).
It was performed by the method described in Mitsugu (1980), Vol. 19, Phys.

Example I Using N-methyl-2-pyrrolidone as a solvent, 0.01 mol of γ-7 minobrobiltriethoxysilane and 0.02 mol of pyromellitic anhydride were added in a water bath so that the temperature was controlled to be 30°C or less. The silane-modified polycarboxylic acid component was synthesized by allowing the reaction to proceed until the reaction system became transparent. Next, 0.1 mole of 2,2-bis[4-(4-amino7enoxy)7enyl]hexafluoropropane was added and completely dissolved, and 0.1 mole of pyromellitic anhydride was added.
09 mol was added and stirred until the reaction system became a clear viscous solution. Although the temperature rose during this operation, a water bath maintained the temperature below 30°C.

5 m of one piece of polyimide silane obtained in this way
A glass substrate (Pll 5 C+A, horizontal 150I11%) on which a transparent electrode of indium oxide, tin oxide, etc. was formed using m% N-methyl-2-pyrrolidone solution using a spinner.
The coating was applied to a thickness of 1 mm). After coating, it was heated at a temperature of 250° C. for 1 hour to cause dehydration and ring closure, thereby forming a polyimide silane film with a thickness of 1000 mm. Next, this polyimide silane film (
Liquid crystal [ZLI-
2293, (Merck & Co. 9I), right-handed chiral agent CB1
5 (manufactured by BDH) to 3.07 for ZLI-2293.
Mixture 1 of 3.33% by weight of a left-handed chiral agent S811 (manufactured by Merck & Co., Ltd.) with respect to ZLI-2293 was sealed to prepare a liquid crystal display element (cell thickness: 6.3μ+a). When a voltage was applied to this device and the orientation and contrast were observed, it was found to be extremely good, and there was no variation within the display panel. Further, when the pretilt angle was measured, it was 12.5 degrees over the entire surface of the display panel, and the variation was extremely small.

Further, when this element was left at a temperature of 70° C. and 95% RH for 1000 hours and the orientation characteristics were observed, no defects such as bleeding occurred, and the leakage current value was almost the same as the initial value.

Examples 2 to 4 In Example 1, only the heat treatment conditions and rubbing conditions were changed as shown in Table 1, and the characteristics of the ponds were evaluated in the same manner as in Example 1.

Example 5 In Example 1, 3 was used instead of pyromellitic anhydride.
・Using 3', 4, 4'-diphenyltetracarboxylic acid anhydride, and replacing 2,2-bis[. The same procedure as Example 1 was carried out except that 4-(4-7minophenoxy)phenyl-1propane was used.

The results of each of the above examples are shown in Table 1.

Comparative Example 1 Using N-methyl-2-pyrrolidone as a solvent, 0.1 mol of bilomerino)M anhydride and 2,2-bis[4-(4-7
Mi/7 enoxy) phenyl 1 hexafluoropropane 0
．． 1 mol was reacted in a water bath at a temperature of 30° C. or lower for 5 hours to obtain a polyimide precursor.

Table 1 below shows the results of characteristic evaluation conducted in the same manner as in Example 1.

Comparative Examples 2 to 2 were evaluated in the same manner as in Example 1 except that only the heat treatment conditions and rubbing conditions were changed as shown in Table 1.

The results are shown in Table 1.

Comparative Example 5 Using N-methyl-2-pyrrolidone as a solvent, 0.1 mol of pyromellitic anhydride, 0.1 mol of 2,2-bis[t-(4-7minophenoxy)phenyl 1 hexafluoropropane]
09 mol and 1,3-bis(γ-amino/propyl)-1
- A polyimide precursor was obtained in the same manner as in Example 1 using 0.01 mol of 1,3-tetramethylnonoxane.

Table 1 below shows the results of characteristic evaluation conducted in the same manner as in Example 1.

Comparative Example 6 0.01 mol of γ-amino/propyltrimethoxysilane was then added to the polyimide precursor obtained in Comparative Example 1, stirred thoroughly for 1' until uniform, and then immediately added to Example 1.
In the same manner as in 1, Y property 1't'T' value was carried out.

Comparative Example 7 A polyimide precursor was obtained in the same manner as in Example 1, except that γ-fried propyltriethoxysilane was used instead of γ-amino/propyltriethoxysilane.

Table 1 below shows the results of characteristic evaluation conducted in the same manner as in Example 1.

Comparative Example 8 A polyimide precursor was obtained in the same manner as in Example 1, except that N-phenyl-γ-ami/propyltrimethoxysilane was used instead of γ-7 minopropyltrietoxin run. Ta.

Table 1 below shows the results of characteristic evaluation conducted in the same manner as in Example 1.

(The following is a blank space) From the results shown in Table 11, it is recognized that each of the examples was superior to the comparative example in terms of adhesion to the substrate, uniformity of contrast, and pretilt angle.

Furthermore, it is recognized that the variations in the pretilt angle of each example are smaller and the reliability is higher than that of the comparative example.

(g) Effects of the invention The liquid crystal sandwiching substrate made of the polyimide silane film as a liquid crystal alignment film according to the present invention can maintain a high pretilt angle of liquid crystal molecules, and the pretilt angle is determined by the heat treatment conditions during film formation and the rubbing conditions. It does not change depending on the conditions, and it also has excellent adhesion to glass substrates, etc., and can maintain a good orientation state stably for a long time.Moreover, the polyimide powder has excellent heat resistance and electrical insulation properties. , a high pretilt angle can be stabilized with the minimum amount of silane modification that does not impair various properties such as aging properties, and stable liquid crystal orientation can be obtained.
The pretilt angle can also be stably maintained at a high level without variation, resulting in high long-term reliability.

In addition, because it has such excellent characteristics, it is ideal as a liquid crystal sandwiching substrate for high-quality SBE type liquid crystal display elements, which require uniform high-tilt alignment of liquid crystal molecules over a large area. It is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal sandwiching substrate of the present invention, and FIG. 2 is a sectional view showing an example of a product cell formed using the same. (1)...Substrate, (2)...Transparent electrode, (3)...
- Polyimide silane film (liquid crystal alignment film), (4)...resin seal, (5)...liquid crystal composition.

Claims (1)

[Claims] (1) A liquid crystal sandwiching substrate comprising a liquid crystal alignment film provided on a substrate on which electrodes are formed, wherein the liquid crystal alignment film is an imidized product of the following polyimide silane precursor. Below is the general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………………………(
I) [However, Ar in the formula indicates [▲There are mathematical formulas, chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] At least one component selected from organic tetracarboxylic acid anhydrides represented by the following general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……………………(I
I) [However, in the formula, R_1 to R_4 are hydrogen, lower alkyl group,
It represents a lower alkoxy group, chlorine or bromine, and may be the same or different. Further, in the formula, R_5 and R_6 are hydrogen, a methyl group, an ethyl group, a trifluoromethyl group, or a trichloromethyl group, and may be the same or different. ] At least one selected from the diamine compounds represented by
When producing a polyimidosilane precursor by a polymerization reaction with a seed component, a part of the organic tetracarboxylic anhydride represented by the above general formula (I) is preliminarily converted into a polyimide silane precursor by the following general formula (I).
II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………………………(I
II) [In the formula, R_7 is a linear methylene group represented by ■CH_2■_n (an integer of 1 to 10] or a branched isomer thereof, and X is selected from an alkoxy group, an acetoxy group, a phenoxy group, or a halogen) The hydrolyzable group Y is a group selected from an alkyl group, an alkoxy group or an acetoxy group. A silane-modified polycarboxylic acid component is obtained by reacting with an aminosilane compound represented by the following, and the silane-modified polycarboxylic acid component is polymerized with the diamine represented by the above general formula (II) together with the remaining organic tetracarboxylic acid component. A polyimide silane precursor made by