JPWO2007102513A1 - Silicon-based liquid crystal aligning agent, liquid crystal aligning film, and production method thereof - Google Patents

Abstract

（Ｒ^１は炭素数８〜３０の有機基であり、Ｒ^２は炭素数１〜５の炭化水素基を表す。）
ポリシロキサン（Ｂ）：式（２）で表されるテトラアルコキシシランを含有するアルコキシシランを重縮合して得られるポリシロキサン。

（Ｒ^３は炭素数１〜５の炭化水素基を表す。）An object of the present invention is to provide a silicon-based liquid crystal aligning agent capable of obtaining a liquid crystal aligning film having good liquid crystal alignment and having a high voltage holding ratio in element driving at a low frequency under high temperature, and a method for producing the same. That is.
A liquid crystal aligning agent comprising the following polysiloxane (A) and polysiloxane (B).
Polysiloxane (A): polysiloxane obtained by polycondensation of alkoxysilane containing alkoxysilane represented by formula (1),

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B): polysiloxane obtained by polycondensation of alkoxysilane containing tetraalkoxysilane represented by the formula (2).

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.)

Description

  The present invention relates to a liquid crystal aligning agent mainly containing a polysiloxane mixture obtained by polycondensation of alkoxysilane, a method for producing the same, a liquid crystal aligning film obtained from the liquid crystal aligning agent, and a liquid crystal display device having the liquid crystal aligning film About.

The liquid crystal display element has a structure in which two substrates, each having a liquid crystal alignment film mainly composed of polyamic acid or polyimide on a transparent electrode, are arranged to face each other, and a liquid crystal material is filled in a gap between the substrates. Generally known. The most well-known method is a TN (Twisted Nematic) type liquid crystal display element. However, an STN (Super Twisted Nematic) type that can realize a higher contrast ratio than this, and an IPS (Super Twisted Nematic) type that has less viewing angle dependency. In-plane switching (VA) and vertical alignment (VA) types have been developed.
Among them, a vertical alignment type liquid crystal display element driven by a thin film transistor (TFT) has a fast response speed, an ultra-wide viewing angle, and a high contrast, and MVA demands higher quality. New vertical alignment type liquid crystal display elements such as (Multi-domain Vertical Alignment), ASV (Advanced Super View), and PVA (Patterned Vertical Alignment) have been proposed.
It is known that the liquid crystal alignment film provided in these liquid crystal display elements aligns the liquid crystal and greatly affects various characteristics such as electric characteristics of the liquid crystal display element. Therefore, a liquid crystal alignment film suitable for such a new vertical alignment type display element has been developed.

For example, as a liquid crystal alignment film that obtains good vertical alignment, a method of introducing a long alkyl chain into polyamic acid or polyimide (see, for example, Patent Document 1) or a method of introducing a cyclic substituent has been proposed. (For example, refer to Patent Document 2.)
In addition, a method for introducing a specific cyclic substituent into polyamic acid or polyimide has been proposed for the purpose of imparting electrical characteristics such as high voltage holding ratio and low residual DC to the device together with good vertical alignment. (For example, refer to Patent Document 3.)
Recently, a metal halide lamp with high irradiation intensity has been used as a light source for a liquid crystal projector for business use and home theater, and a liquid crystal alignment film material having high resistance to light as well as heat has been required. As one of the solutions, it has been proposed to apply a material different from the conventional polyamic acid or polyimide liquid crystal alignment film to the liquid crystal alignment film.

For example, a liquid crystal aligning agent composition containing a reaction product of tetraalkoxysilane, trialkoxysilane and water, and a glycol ether solvent has been proposed, which prevents display defects and has residual characteristics even after long-time driving. Development of a liquid crystal aligning agent that can form a liquid crystal alignment film that does not deteriorate the ability to align liquid crystals and that has little decrease in voltage holding ratio against light and heat has been made. (For example, see Patent Document 4)
As described above, while the liquid crystal display element becomes highly functional, improvement of the reliability of the element has become a bigger problem than ever.

Conventionally, the reliability, particularly the electrical reliability, of a TFT type liquid crystal display element has been confirmed by the voltage holding ratio corresponding to the 30 Hz operation of the liquid crystal display element and its temperature characteristics. It was difficult to detect the difference. Therefore, as a method for confirming higher reliability, a method has been proposed in which the voltage holding ratio is measured by driving the element at a low frequency so as to widen the interval between pulse voltages applied to the liquid crystal display element. (For example, refer to Patent Document 5.)
The reliability of the liquid crystal display element is very important because it directly affects the yield improvement in the manufacturing process as well as the reliability with respect to the display characteristics of monitors and televisions.

  Furthermore, in recent years, in a situation where the liquid crystal display element is increased in size, it is said that the yield in the manufacturing process has a greater influence on the productivity of the liquid crystal display element than before, and the electrical reliability of the liquid crystal display element is very difficult. It has been regarded as important. That is, to improve the productivity of large liquid crystal display elements, it is essential to improve the reliability of the liquid crystal display elements. In particular, in a vertical alignment type liquid crystal display element often used for television and projector applications, the importance of reliability in electrical characteristics is large, and therefore, the liquid crystal alignment is good and the low frequency under high temperature. There is a growing demand for a liquid crystal alignment film that can provide device characteristics of high voltage holding ratio in device driving.

Japanese Patent Laid-Open No. 06-3678 JP 09-278724 A JP 2001-311080 A JP 2005-250244 A JP 2001-264805 A

  The present invention relates to a silicon-based liquid crystal aligning agent capable of obtaining a liquid crystal alignment film having good liquid crystal alignment and having a high voltage holding ratio in element driving at a low frequency under high temperature, a method for manufacturing the same, and silicon-based liquid crystal alignment. It aims at providing the liquid crystal aligning film obtained from an agent, and the liquid crystal display element which has the said liquid crystal aligning film.

（Ｒ^１は炭素数８〜３０の有機基であり、Ｒ^２は炭素数１〜５の炭化水素基を表す。）
ポリシロキサン（Ｂ）：式（２）で表されるテトラアルコキシシランを含有するアルコキシシランを重縮合して得られるポリシロキサン。但し、式（１）で表されるアルコキシシランを併用しない。

（Ｒ^３は炭素数１〜５の炭化水素基を表す。）As a result of intensive studies in view of the above situation, the present inventors have completed the present invention.
That is, the present invention has the following gist.
1. A liquid crystal aligning agent comprising the following polysiloxane (A), polysiloxane (B), and an organic solvent that dissolves these polysiloxanes.
Polysiloxane (A): polysiloxane obtained by polycondensation of alkoxysilane containing alkoxysilane represented by formula (1),

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B): polysiloxane obtained by polycondensation of alkoxysilane containing tetraalkoxysilane represented by the formula (2). However, the alkoxysilane represented by the formula (1) is not used in combination.

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.)

（Ｒ^１は炭素数８〜３０の有機基であり、Ｒ^２は炭素数１〜５の炭化水素基を表す。）
ポリシロキサン（Ｂ）の溶液：式（２）で表されるテトラアルコキシシランを含有するアルコキシシランを有機溶媒中で重縮合して得られるポリシロキサンの溶液。但し、式（１）で表されるアルコキシシランを併用しない。

（Ｒ^３は炭素数１〜５の炭化水素基を表す。）2. A liquid crystal aligning agent comprising the following polysiloxane (A) solution and polysiloxane (B) solution.
Solution of polysiloxane (A): a solution of polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1) in an organic solvent,

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B) solution: A polysiloxane solution obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2) in an organic solvent. However, the alkoxysilane represented by the formula (1) is not used in combination.

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.)

  3. 3. The liquid crystal aligning agent according to 1 or 2 above, wherein the polysiloxane (A) is a polysiloxane obtained by polycondensation using at least one of the alkoxysilanes represented by the formula (3).

（Ｒ^４はそれぞれ炭素数１〜５の炭化水素基であり、Ｒ^５は水素原子又は炭素数１〜５の有機基であり、ｎは０〜３の整数を表す。）

(R ⁴ is a hydrocarbon group having 1 to 5 carbon atoms, R ⁵ is a hydrogen atom or an organic group having 1 to 5 carbon atoms, and n represents an integer of 0 to 3)

  4). 4. The liquid crystal aligning agent according to 1 to 3, wherein the polysiloxane (B) is a polysiloxane obtained by polycondensation using at least one of the alkoxysilanes represented by the formula (4).

（Ｒ^６は炭素数１〜５の炭化水素基を表し、Ｒ^７は水素原子又は炭素数１〜６の有機基を表し、ｍは１又は２の整数を表す。）

(R ⁶ represents a hydrocarbon group having 1 to 5 carbon atoms, R ⁷ represents a hydrogen atom or an organic group having 1 to 6 carbon atoms, and m represents an integer of 1 or 2.)

5. The polysiloxane (A) is a polysiloxane obtained by polycondensation of alkoxysilane and tetraethoxysilane represented by the formula (1), and the polysiloxane (B) is obtained by polycondensation of tetraethoxysilane. 3. The liquid crystal aligning agent according to 1 or 2 above, which is siloxane.
6). The liquid crystal according to 1 to 5 above, wherein the polysiloxane (A) is a polysiloxane obtained by polycondensation of an alkoxysilane containing 2 to 30 mol% of the alkoxysilane represented by the formula (1). Alignment agent.
7). 7. The liquid crystal alignment according to 1 to 6, wherein the amount of silicon atoms in the polysiloxane (A) is 3 to 80 mol% with respect to the total amount of silicon atoms in the polysiloxane (A) and the polysiloxane (B). Agent.

8). 8. A liquid crystal alignment film obtained using the liquid crystal aligning agent according to 1 to 7 above.
9. 9. A liquid crystal display device having the liquid crystal alignment film according to 8 above.
10. The manufacturing method of the liquid crystal aligning agent characterized by including the process of mixing the solution of the following polysiloxane (A), and the solution of polysiloxane (B).
Solution of polysiloxane (A): a solution of polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1) in an organic solvent,

（Ｒ^１は炭素数８〜３０の有機基であり、Ｒ^２は炭素数１〜５の炭化水素基を表す。）

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)

  Polysiloxane (B) solution: A polysiloxane solution obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2) in an organic solvent. However, the alkoxysilane represented by the formula (1) is not used in combination.

（Ｒ^３炭素数１〜５の炭化水素基を表す。）

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.)

11. 11. The method for producing a liquid crystal aligning agent according to 10 above, wherein the polysiloxane (A) solution is a polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1).
12 The method for producing a liquid crystal aligning agent according to 10 or 11 above, wherein the polysiloxane (B) solution is a polysiloxane obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2). .

According to the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal aligning film having good liquid crystal alignment and having a high voltage holding ratio in element driving at a low frequency at high temperature. Therefore, a highly reliable liquid crystal display element can be provided.
It is not always clear why the above effects are achieved by the present invention. However, in the case of the liquid crystal alignment film using the liquid crystal aligning agent of the present invention, as is apparent from FIG. Has the structure. This structure seems to be related to the characteristics of the liquid crystal alignment film of the present invention.

It is the result of having analyzed the distribution of the element in the substrate direction from the surface of a film about the liquid crystal aligning film obtained from the liquid crystal aligning agent (L5) of the present invention. It is the result of having analyzed the distribution of the element from the film | membrane surface to a board | substrate direction about the coating film obtained from the polysiloxane solution (P2) of the comparative example 1. FIG.

The present invention is described in detail below.
<Polysiloxane (A)>
The polysiloxane (A) used in the present invention is obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1).

R ^{1 in the} formula (1) is an organic group having 8 to 30 carbon atoms, and is a ring structure such as an aliphatic hydrocarbon, an aliphatic ring, an aromatic ring and a heterocyclic ring, an unsaturated bond, an oxygen atom, It may contain a hetero atom such as a nitrogen atom or a sulfur atom, and may have a branched structure. In addition, the organic group may be substituted with a halogen atom, vinyl group, amino group, glycidoxy group, mercapto group, ureido group, methacryloxy group, isocyanate group, acryloxy group, or the like.
Specific examples of such organic group R ¹ include alkyl group, perfluoroalkyl group, alkenyl group, allyloxyalkyl group, phenethyl group, perfluorophenylalkyl group, phenylaminoalkyl group, styrylalkyl group, naphthyl group. Benzoyloxyalkyl group, alkoxyphenoxyalkyl group, cycloalkylaminoalkyl group, epoxycycloalkyl group, N- (aminoalkyl) aminoalkyl group, N- (aminoalkyl) aminoalkylphenethyl group, bromoalkyl group, diphenylphosphino Group, N- (methacryloxyhydroxyalkyl) aminoalkyl group, N- (acryloxyhydroxyalkyl) aminoalkyl group and the like.
Among them, the organic group ^{R 1,} preferably an alkyl group having 8 to 30 carbon atoms, more preferably an alkyl group having 8 to 20 carbon atoms.

R ^{2 in the} formula (1) represents a hydrocarbon group, and a saturated hydrocarbon group having 1 to 5 carbon atoms is preferable because the smaller the number of carbon atoms, the higher the reactivity. More preferred are a methyl group, an ethyl group, a propyl group, and a butyl group.
In the present invention, at least one of the alkoxysilanes represented by the formula (1) may be used, but a plurality of types may be used as necessary.

  Specific examples of the alkoxysilane represented by the formula (1) include octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyl. Trimethoxysilane, hexadecyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, nonadecyltrimethoxysilane, nonadecyltriethoxysilane, undecyltriethoxysilane, Undecyltrimethoxysilane, 21-docosenyltriethoxysilane, allyloxyundecyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecuff Orooctyltriethoxysilane, isooctyltriethoxysilane, phenethyltriethoxysilane, pentafluorophenylpropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, N- (triethoxysilylpropyl) dansyriamid, styrylethyltriethoxysilane, ( R) -N-1-phenylethyl-N′-triethoxysilylpropylurea, (1-naphthyl) triethoxysilane, (1-naphthyl) trimethoxysilane, m-styrylethyltrimethoxysilane, p-styrylethyltri Methoxysilane, N- [3- (triethoxysilyl) propyl] phthalamic acid, 1-trimethoxysilyl-2- (p-aminomethyl) phenylethane, 1-trimethoxysilyl-2- (m-aminomethyl) Phenylethane, benzoyloxypropyltrimethoxysilane, 3- (4-methoxyphenoxy) propyltrimethoxysilane, N-triethoxysilylpropylquinine urethane, 3- (N-cyclohexylamino) propyltrimethoxysilane, 1-[(2 -Triethoxysilyl) ethyl] cyclohexane-3,4-epoxide, N- (6-aminohexyl) aminopropyltrimethoxysilane, aminoethylaminomethylphenethyltrimethoxysilane, 11-bromoundecyltrimethoxysilane, 2- ( Diphenylphosphino) ethyltriethoxysilane, N- (3-methacryloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane, N- (3-acryloxy-2-hydroxypropyl) -3-amino-propyl Examples include propyltriethoxysilane.

The polysiloxane (A) used in the present invention is obtained by polycondensation of an alkoxysilane containing the formula (1), but it may be in a homogeneous solution state in a solvent.
In particular, the polysiloxane (A) used in the present invention is preferably a polycondensate of an alkoxysilane represented by the formula (1) and an alkoxysilane represented by the following formula (3).

R ^{4 in} formula (3) represents a hydrocarbon group having 1 to 5 carbon atoms, preferably a saturated hydrocarbon group having 1 to 5 carbon atoms, more preferably a methyl group, an ethyl group, a propyl group, or a butyl group. It is.
Then, a ^{R 5} is a hydrogen atom or an organic group having 1 to 5 carbon atoms of the formula (3). The organic group is not particularly limited as long as it has 1 to 5 carbon atoms. And this organic group may contain hetero atoms, such as an oxygen atom, a nitrogen atom, and a sulfur atom, and may have an unsaturated bond and a ring structure. Further, saturated hydrocarbon groups such as methyl group, ethyl group, isopropyl group and n-propyl group, unsaturated hydrocarbon groups such as vinyl group, amino group, glycidoxy group, mercapto group, ureido group, isocyanate group, etc. May be substituted.
N of Formula (3) represents the integer of 0-3. In particular, when n is 0, it represents tetraalkoxysilane.

  Specific examples of the alkoxysilane represented by the formula (3) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, Ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, methyltripropoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 2-aminoethyl Aminomethyltrimethoxysilane, 2- (2-aminoethylthioethyl) triethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxy Examples thereof include silane, allyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, trifluoropropyltrimethoxysilane, chloropropyltriethoxysilane, and bromopropyltriethoxysilane.

The alkoxysilane represented by the formula (3) used in the present invention can be used singly or as needed as needed.
In the present invention, among the alkoxysilanes represented by the formula (3), it is easy to polycondense with the alkoxysilane represented by the formula (1) by using a tetraalkoxysilane in which n is 0. It is preferable for obtaining polysiloxane (A).

When the use ratio of the alkoxysilane represented by the formula (1) is less than 2 mol% in the total alkoxysilane used to obtain the polysiloxane (A), good liquid crystal alignment cannot be obtained. Therefore, 2 mol% or more is preferable. More preferably, it is 3 mol% or more. Moreover, when it exceeds 30 mol%, since the liquid crystal aligning film formed may not fully harden | cure, 30 mol% or less is preferable. More preferably, it is 22 mol% or less.
In the present invention, one or more of the above-described polysiloxanes (A) can be used.

<Solution of polysiloxane (A)>
In the present invention, the solution of polysiloxane (A) described above is preferably a uniformly dissolved solution obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1) in an organic solvent. Among them, the polysiloxane (A) solution is a solution in which an alkoxysilane represented by the formula (1) and an alkoxysilane represented by the formula (3) are used in combination and are uniformly dissolved in an organic solvent. preferable.

The method for polycondensing the polysiloxane (A) used in the present invention is not particularly limited, and examples thereof include a method of hydrolyzing and polycondensing alkoxysilane in an alcohol or glycol solvent. At that time, the hydrolysis / polycondensation reaction may be either partial hydrolysis or complete hydrolysis. In the case of complete hydrolysis, theoretically, it is sufficient to add 0.5 times mole of water of all alkoxy groups in the alkoxysilane, but it is usually preferable to add an excess amount of water more than 0.5 times mole.
In the present invention, the amount of water used in the above reaction can be appropriately selected as desired, but it is usually preferably 0.5 to 2.5 moles of all alkoxy groups in the alkoxysilane.

Usually, for the purpose of promoting hydrolysis and polycondensation reaction, acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, succinic acid and maleic acid, alkalis such as ammonia, methylamine, ethylamine, ethanolamine and triethylamine, hydrochloric acid Catalysts such as metal salts such as sulfuric acid and nitric acid are used.
In addition, it is also common to further promote hydrolysis and polycondensation reactions by heating a solution in which alkoxysilane is dissolved. At that time, the heating temperature and the heating time can be appropriately selected as desired. Examples thereof include heating and stirring at 50 ° C. for 24 hours and heating and stirring for 1 hour under reflux.

  As another method, for example, a method of heating and polycondensing a mixture of alkoxysilane, a solvent and oxalic acid can be mentioned. Specifically, after adding succinic acid to alcohol in advance to obtain an alcohol solution of succinic acid, alkoxysilane is mixed while the solution is heated. In that case, the amount of succinic acid used is generally 0.2 to 2 mol with respect to 1 mol of all alkoxy groups of the alkoxysilane. The heating in this method can be performed at a liquid temperature of 50 to 180 ° C., and preferably, for example, in a sealed container or under reflux, several tens to several dozens so that the liquid does not evaporate or volatilize. Done for hours.

  In the case of using a plurality of alkoxysilanes when obtaining the polysiloxane (A), the alkoxysilanes may be mixed in advance to form a mixture, or a plurality of alkoxysilanes may be sequentially mixed.

  The solvent used for polycondensation of alkoxysilane is not particularly limited as long as it dissolves alkoxysilane. In general, since an alcohol is generated by a polycondensation reaction of alkoxysilane, an alcohol, a glycol, or an organic solvent having good compatibility with the alcohol is used.

  Specific examples of such organic solvents include methanol, ethanol, propanol, butanol, ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, and ethylene glycol monomethyl. Ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N , N-dimethylacetamide, γ- Examples include butyrolactone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphotriamide, and m-cresol.

In the present invention, a plurality of the above organic solvents may be mixed and used.
The solution of polysiloxane (A) obtained by such a method has a concentration obtained by converting silicon atoms of all alkoxysilanes charged as raw materials into SiO ₂ (hereinafter referred to as SiO ₂ converted concentration) to 20% by mass or less. It is common to do. By selecting an arbitrary concentration within this concentration range, gel formation can be suppressed and a homogeneous solution can be obtained.

In the present invention, the solution obtained by the above-described method may be used as it is as the polysiloxane (A) solution. If necessary, the solution obtained by the above-described method may be concentrated or a solvent may be added. The solution of polysiloxane (A) may be diluted or replaced with another solvent.
In this case, the solvent used may be the same solvent used for the polycondensation or may be another solvent. This solvent is not particularly limited as long as the polysiloxane (A) is uniformly dissolved, and one kind or a plurality of kinds can be arbitrarily selected and used.

  Specific examples of such solvents include alcohols such as methanol, ethanol, propanol, butanol and diacetone alcohol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol and the like Glycols: methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl Ether, propi Glycol ethers such as N-glycol monobutyl ether; esters such as methyl acetate, ethyl acetate, and ethyl lactate; N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, γ- Examples include butyrolactone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphotriamide, and m-cresol.

  In the present invention, one or more of the polysiloxane (A) solutions obtained as described above may be used.

<Polysiloxane (B)>
The polysiloxane (B) used in the present invention is a polysiloxane obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2). However, the alkoxysilane represented by the formula (1) is not used in combination.

R ^{3 in the} above formula (2) is a hydrocarbon group having 1 to 5 carbon atoms. However, since the reactivity is higher when the number of carbon atoms is smaller, a saturated hydrocarbon group having 1 to 5 carbon atoms is preferable. More preferred are a methyl group, an ethyl group, a propyl group, and a butyl group.
Specific examples of the tetraalkoxysilane represented by the above formula (2) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane and the like, which are easily available as commercial products.
In this invention, polysiloxane (B) can also use together the tetraalkoxysilane represented by Formula (2), and at least 1 sort (s) of the alkoxysilane represented by following formula (4).

The alkoxysilane represented by the above formula (4) is a so-called bifunctional or trifunctional alkoxysilane having preferably two or three alkoxy groups.
R ^{6 in the} formula (4) is a hydrocarbon group having 1 to 5 carbon atoms, similarly to R ³ , but the lower the number of carbon atoms, the higher the reactivity, so the saturated hydrocarbon having 1 to 5 carbon atoms. Groups are preferred. More preferred are a methyl group, an ethyl group, a propyl group, and a butyl group.

R ⁷ in the above formula (4) represents a hydrogen atom or an organic group having 1 to 6 carbon atoms, preferably 1 to 5 carbon atoms. Examples of such an organic group include an aromatic group, an aliphatic group, and a group having an alicyclic structure. Among the more preferable organic groups having 1 to 5 carbon atoms, an aliphatic group having 1 to 5 carbon atoms is preferable, and a saturated hydrocarbon group having 1 to 5 carbon atoms is more preferable. Specific examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group.

  Specific examples of the alkoxysilane represented by the formula (4) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, Methyltripropoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, 2- (2-aminoethylthioethyl) tri Ethoxysilane, -Mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, allyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, trifluoropropyltrimethoxysilane , Chloropropyltriethoxysilane, bromopropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethoxydiethylsilane, dibutoxydimethylsilane, diethoxymethylvinylsilane, diethoxydivinylsilane, 3-aminopropyldiethoxymethylsilane , 3-mercaptopropylmethyldimethoxysilane, 2- (2-aminoethylthioethyl) diethoxymethylsilane, dimethoxy Chill-3,3,3-trifluoropropylsilane, 3-chloropropyldimethoxymethylsilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydiphenylsilane, diethoxydiphenylsilane, methoxytriphenylsilane, ethoxytriphenylsilane, Examples include cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, cyclopentyltrimethoxysilane, and cyclopentyltriethoxysilane.

In the present invention, at least one tetraalkoxysilane represented by the formula (2) may be used, but a plurality of types may be used as necessary. Furthermore, the alkoxysilane represented by Formula (4) can also be used together, In that case, you may use multiple types of alkoxysilane represented by Formula (4).
In addition, commercially available polysiloxanes such as methyl silicate 51 and ethyl silicate 40 manufactured by Colcoat can be used in combination.
The polysiloxane (B) used in the present invention is obtained by polycondensation of a tetraalkoxysilane containing the formula (2), but may be in a homogeneous solution state in a solvent.
In the present invention, the above-mentioned polysiloxane (B) can be used alone or in combination.

<Polysiloxane (B) solution>
In the present invention, the solution of polysiloxane (B) described above is preferably a uniformly dissolved solution obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2) in an organic solvent. However, the alkoxysilane represented by the formula (1) is not used in combination. At that time, a solution in which tetraalkoxysilane represented by formula (2) alone or a polycondensation of alkoxysilane represented by formula (2) and formula (4) is uniformly dissolved is preferable. The polysiloxane (B) solution is obtained as a solution uniformly dissolved in an organic solvent.

The method for obtaining the polysiloxane (B) used in the present invention is not particularly limited. For example, it can be obtained by a method of hydrolyzing and polycondensing alkoxysilane in an alcohol or glycol solvent. At that time, the hydrolysis / polycondensation reaction may be either partial hydrolysis or complete hydrolysis. In the case of complete hydrolysis, theoretically, it is sufficient to add 0.5 moles of water of all alkoxy groups in the alkoxysilane, but usually an excess amount of water is added from 0.5 moles.
In the present invention, the amount of water used in the above reaction can be appropriately selected as desired, but it is usually 0.5 to 2.5 moles of all alkoxy groups in the alkoxysilane.
Usually, for the purpose of promoting hydrolysis and polycondensation reaction, acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, succinic acid and maleic acid, alkalis such as ammonia, methylamine, ethylamine, ethanolamine and triethylamine, hydrochloric acid Catalysts such as metal salts such as sulfuric acid and nitric acid are used.
In addition, it is also common to further promote hydrolysis and polycondensation reactions by heating a solution in which alkoxysilane is dissolved. At that time, the heating temperature and the heating time can be appropriately selected as desired. Examples thereof include heating and stirring at 50 ° C. for 24 hours and heating and stirring for 1 hour under reflux.

  As another method, for example, a method of heating and polycondensing a mixture of alkoxysilane, a solvent and oxalic acid can be mentioned. Specifically, after adding succinic acid to alcohol in advance to obtain an alcohol solution of succinic acid, alkoxysilane is mixed while the solution is heated. At that time, the amount of succinic acid is generally 0.2 to 2 mol relative to 1 mol of all alkoxy groups of alkoxysilane. The heating in this method can be performed at a liquid temperature of 50 to 180 ° C., and preferably, for example, in a sealed container or under reflux, a few tens to a dozen or more so as not to cause evaporation or volatilization of the liquid. Done for hours.

  When using multiple types of alkoxysilane when obtaining polysiloxane (B), you may mix as a mixture which mixed alkoxysilane beforehand, and may mix multiple types of alkoxysilane sequentially.

  The solvent used for polycondensation of alkoxysilane is not particularly limited as long as it dissolves alkoxysilane. In general, since an alcohol is generated by a polycondensation reaction of tetraalkoxysilane, an organic solvent having good compatibility with alcohols, glycols, and alcohols is used.

Specific examples of such organic solvents include methanol, ethanol, propanol, butanol, ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, and ethylene glycol monomethyl. Ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N , N-dimethylacetamide, γ- Examples include butyrolactone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphotriamide, and m-cresol.
In the present invention, a plurality of the above organic solvents may be mixed and used.

The polysiloxane (B) solution obtained by such a method generally has a SiO ₂ equivalent concentration of 20% by mass or less. By selecting an arbitrary concentration within this concentration range, gel formation can be suppressed and a homogeneous solution can be obtained.

In the present invention, the solution obtained by the above method may be used as it is as the polysiloxane (B) solution, or the solution obtained by the above method may be concentrated or a solvent may be added if necessary. The solution of polysiloxane (B) may be diluted or replaced with another solvent.
In this case, the solvent used may be the same solvent used for the polycondensation or may be another solvent. The solvent is not particularly limited as long as the polysiloxane (B) is uniformly dissolved, and one kind or plural kinds of solvents can be arbitrarily selected and used.

Specific examples of such solvents include alcohols such as methanol, ethanol, propanol, butanol and diacetone alcohol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol and the like Glycols: methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl Ether, propi Glycol ethers such as N-glycol monobutyl ether; esters such as methyl acetate, ethyl acetate, and ethyl lactate; N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, γ- Examples include butyrolactone, dimethyl sulfoxide, tetramethylurea, hexamethylphosphotriamide, and m-cresol.
In the present invention, the polysiloxane (B) solution obtained as described above may be used singly or in combination.

<Other ingredients>
In the present invention, other components than polysiloxane (A) and polysiloxane (B), for example, inorganic fine particles, leveling agents, and further surfactants are included as long as the effects of the present invention are not impaired. It may be.

As the inorganic fine particles, fine particles such as silica fine particles, alumina fine particles, titania fine particles, and magnesium fluoride fine particles are preferable, and those of a colloidal solution are particularly preferable. This colloidal solution may be a dispersion of inorganic fine particle powder in a dispersion medium or a commercially available colloidal solution. In the present invention, the inclusion of inorganic fine particles makes it possible to impart the surface shape of the formed cured film and other functions. The inorganic fine particles preferably have an average particle size of 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm. When the average particle diameter of the inorganic fine particles exceeds 0.2 μm, the transparency of the cured film formed using the prepared coating liquid may be lowered.
Examples of the dispersion medium for the inorganic fine particles include water and organic solvents. As a colloidal solution, it is preferable that pH or pKa is adjusted to 2 to 10 from the viewpoint of the stability of the coating liquid for forming a film. More preferably, it is 3-7.

  Organic solvents used for the dispersion medium of the colloidal solution include alcohols such as methanol, propanol, ethylene glycol, butanol and ethylene glycol monopropyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene Amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; esters such as ethyl acetate, butyl acetate and γ-butyrolactone; ethers such as tetrahydrofuran and 1,4-dioxane. Of these, alcohols and ketones are preferred. These organic solvents can be used alone or in admixture of two or more as a dispersion medium.

  Moreover, a leveling agent, surfactant, etc. can use a well-known thing, and since a commercial item is easy to acquire especially, it is preferable.

<Preparation of liquid crystal aligning agent>
The method for preparing the liquid crystal aligning agent of the present invention is not particularly limited. The polysiloxane (A) and the polysiloxane (B) may be in a state where other components are uniformly mixed as required. Usually, since polysiloxane (A) and polysiloxane (B) are polycondensed in a solvent, each is obtained in a solution state. Therefore, the polysiloxane (A) solution and polysiloxane (B) already described above are used. The method of mixing the solution of) is simple. Moreover, a solvent can also be added after mixing the solution of polysiloxane (A) and the solution of polysiloxane (B) as needed.
At this time, SiO ₂ concentration in terms of liquid crystal alignment agent, 0.5 to 15% by mass. Within such a SiO ₂ equivalent concentration range, it is easy to obtain a desired film thickness by a single application, and a sufficient pot life of the solution is easily obtained.

In addition, the solvent added after mixing the solution of polysiloxane (A) and the solution of polysiloxane (B) should use the same solvent as described in the solution of polysiloxane (A) and the solution of polysiloxane (B). it can.
The method of mixing the other components described above may be simultaneous with the solution of polysiloxane (A) and the solution of polysiloxane (B) or after mixing them, and is not particularly limited.

  In the present invention, the proportion of polysiloxane (A) used is such that the total amount of silicon atoms in polysiloxane (A) is 3 mol% to 80 with respect to the total amount of silicon atoms in polysiloxane (A) and polysiloxane (B). Mole% is preferred. More preferably, it is 5 mol%-75 mol%. If the total amount of silicon atoms in the polysiloxane (A) is less than 3 mol%, good liquid crystal alignment may not be obtained. If it exceeds 80 mol%, the device is driven by a low frequency at a high temperature. In some cases, it is difficult to obtain a high voltage holding ratio.

In the present invention, specific examples of the liquid crystal aligning agent are listed below.
[1]: A liquid crystal aligning agent containing polysiloxane (A) and polysiloxane (B).
[2]: A liquid crystal aligning agent containing a solution of polysiloxane (A) and a solution of polysiloxane (B).
[3]: The liquid crystal according to the above [1] or [2], wherein the polysiloxane (A) is a polysiloxane obtained by polycondensation of alkoxysilanes represented by the formulas (1) and (3). Alignment agent.
[4]: The polysiloxane (B) is an alkoxysilane represented by the formula (2) or a polysiloxane obtained by polycondensation of the alkoxysilane represented by the formulas (2) and (4). The liquid crystal aligning agent in any one of said [1] to [3].
[5]: A liquid crystal aligning agent containing the liquid crystal aligning agent according to any one of [1] to [4] and inorganic fine particles.
[6]: A liquid crystal aligning agent comprising the liquid crystal aligning agent according to any one of [1] to [5] above and at least one selected from a leveling agent and a surfactant.

<Formation of liquid crystal alignment film>
The liquid crystal aligning agent of this invention can be made into a liquid crystal aligning film by apply | coating to a board | substrate and drying and baking.
Examples of the method for applying the liquid crystal aligning agent include spin coating, printing, ink jet, spraying, roll coating, and the like.In terms of productivity, the transfer printing method is widely used industrially. The liquid crystal aligning agent of the present invention is also preferably used.

The drying process after applying the liquid crystal aligning agent is not necessarily required, but if the time from application to baking is not constant for each substrate, or if baking is not performed immediately after application, a drying process is included. Is preferred. The drying is not particularly limited as long as the solvent is evaporated to such an extent that the shape of the coating film is not deformed by transporting the substrate or the like. For example, a method of drying on a hot plate at a temperature of 50 to 150 ° C., preferably 80 to 120 ° C. for 0.5 to 30 minutes, preferably 1 to 5 minutes can be mentioned.
The coating film formed by applying the liquid crystal aligning agent by the above method can be baked to form a liquid crystal aligning film. In that case, although baking temperature can be performed at 100-350 degreeC arbitrary temperatures, Preferably it is 150-300 degreeC, More preferably, it is 150-220 degreeC, Most preferably, it is 150-200 degreeC.

The polysiloxane (A) and polysiloxane (B) in the liquid crystal alignment film undergo polycondensation in the firing step. However, in the present invention, it is not necessary to completely polycondense unless the effects of the present invention are impaired. However, it is preferable to fire at a temperature that is higher by 10 ° C. or more than the heat treatment temperature required for the manufacturing process of the liquid crystal cell, such as sealing agent curing.
The thickness of the liquid crystal alignment film can be selected as necessary. When the thickness of the liquid crystal alignment film is 5 nm or more, it is preferable because the reliability of the liquid crystal display element is easily obtained. More preferably, it is 10 nm or more. Moreover, the case of 300 nm or less is preferable because the power consumption of the liquid crystal display element does not increase. More preferably, it is 150 nm or less.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention formed by the method as described above has a structure in which polysiloxane (A) is unevenly distributed near the surface layer of the liquid crystal alignment film. This can be confirmed by analyzing the elemental distribution of the liquid crystal alignment film of the present invention from the surface of the film to the substrate by a method such as X-ray photoelectron spectroscopy.
From such an analysis, it is considered that polysiloxane (A) having an effect of aligning the liquid crystal in one direction, particularly in the vertical direction, has an effect that it is likely to be unevenly distributed in the vicinity of the surface layer of the liquid crystal alignment film. .
Therefore, the liquid crystal alignment film of the present invention has a good liquid crystal alignment property, and the liquid crystal display element having the liquid crystal alignment film of the present invention has a high voltage holding ratio in element driving at a low frequency at a high temperature. Has characteristics.

  Furthermore, the liquid crystal alignment film of the present invention has good liquid crystal alignment even when the amount of the alkoxysilane represented by the formula (1) which is a constituent component of the polysiloxane (A) contained in the liquid crystal aligning agent of the present invention is small. And has a characteristic that the voltage holding ratio in driving an element at a low frequency at a high temperature is very high. Specifically, even when the amount of the alkoxysilane represented by the formula (1) in the polysiloxane (A) is 2 to 12 mol%, the liquid crystal orientation is good and the low temperature under high temperature is exhibited. It has a feature that the voltage holding ratio in driving the element by frequency is very high.

  The liquid crystal aligning film of the present invention is obtained from a liquid crystal aligning agent containing polysiloxane (A) and polysiloxane (B), and therefore, compared with a liquid crystal aligning film obtained from a liquid crystal aligning agent of polysiloxane (A) alone. In particular, the voltage holding ratio in the element driving at a low frequency under a high temperature shows a high value.

  The liquid crystal aligning agent of the present invention forms a liquid crystal aligning film having a structure in which polysiloxane (A) is unevenly distributed on the film surface as shown in FIG. 1 in one liquid. ) It has the above-described characteristics as a liquid crystal alignment film that cannot be obtained from a single liquid crystal aligning agent.

<Liquid crystal display element>
The liquid crystal display element of the present invention can be obtained by forming a liquid crystal alignment film on a substrate by the method described above and then preparing a liquid crystal cell by a known method. As an example of producing a liquid crystal cell, a method is generally employed in which a pair of substrates on which a liquid crystal alignment film is formed are fixed with a sealant with a spacer interposed therebetween, and liquid crystal is injected and sealed. In this case, the size of the spacer used is 1 to 30 μm, preferably 2 to 10 μm.
The method for injecting the liquid crystal is not particularly limited, and examples thereof include a vacuum method for injecting liquid crystal after reducing the pressure inside the manufactured liquid crystal cell, and a dropping method for sealing after dropping the liquid crystal.

The substrate used for the liquid crystal display element is not particularly limited as long as it is a highly transparent substrate, but is usually a substrate in which a transparent electrode for driving liquid crystal is formed on the substrate.
Specific examples are glass plate, polycarbonate, poly (meth) acrylate, polyethersulfone, polyarylate, polyurethane, polysulfone, polyether, polyetherketone, trimethylpentene, polyolefin, polyethylene terephthalate, (meth) acrylonitrile, tri Examples thereof include a substrate in which a transparent electrode is formed on a plastic plate such as acetyl cellulose, diacetyl cellulose, and acetate butyrate cellulose.
In a high-performance element such as a thin film transistor (TFT) element, an element in which an element such as a transistor is formed between an electrode for driving liquid crystal and a substrate is used.

In the case of a transmissive liquid crystal element, it is common to use a substrate as described above. However, in a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used if only one substrate is used. It is. At that time, a material such as aluminum that reflects light may be used for the electrode formed on the substrate.
As described above, the liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention has good liquid crystal alignment properties and high voltage holding ratio in element driving at low frequency under high temperature. It is possible to provide a liquid crystal display element having the same.

Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is limited to these and is not interpreted.
The explanation of the abbreviations in this embodiment is as follows.
TEOS: Tetraethoxysilane C10: Decyltrimethoxysilane C12: Dodecyltriethoxysilane C18: Octadecyltriethoxysilane HG: Hexylene glycol BCS: Butyl cellosolve NMP: N-methylpyrrolidone

<Synthesis Example 1>
A 500 ml four-neck reaction flask equipped with a reflux tube was charged with 51.3 g of HG, 15.6 g of BCS and 69.4 g of TEOS, and stirred to prepare an alkoxysilane monomer solution. To this solution, an oxalic acid solution in which HG25.6 g, 7.8 g of BCS, 30.0 g of water and 0.3 g of oxalic acid as a catalyst were mixed in advance was added dropwise at room temperature, and the mixture was stirred for 30 minutes after the completion of the addition. Thereafter, the solution was heated at a solution temperature of 70 ° C. for 1 hour and then allowed to cool to obtain a solution (Z1). HG, BCS and NMP are added to this solution (Z1) so that the solvent mass ratio is HG: BCS: NMP = 30: 50: 20 and the SiO ₂ equivalent concentration is 3.5% by mass. To obtain a polysiloxane solution (P1).

<Synthesis Example 2>
A 500 ml four-necked reaction flask equipped with a reflux tube was charged with HG 47.8 g, BCS 14.5 g, TEOS 55.6 g, and alkoxysilane monomer (X) as C2.2 (22.2 g) and stirred to prepare a mixed solution of alkoxysilane monomer. Prepared. To this solution, an oxalic acid solution in which HG 23.9 g, BCS 7.3 g, water 28.5 g, and 0.3 g of oxalic acid as a catalyst were mixed in advance was added dropwise at room temperature, and stirred for 30 minutes after the completion of the addition. Thereafter, the solution was heated at a solution temperature of 70 ° C. for 1 hour and then allowed to cool to obtain a solution (Z2). HG, BCS and NMP are added to this solution (Z2) so that the solvent mass ratio is HG: BCS: NMP = 30: 50: 20 and the SiO ₂ equivalent concentration is 3.5% by mass. To obtain a polysiloxane solution (P2).

<Synthesis Examples 3 to 10>
Solutions (Z3 to Z10) having the compositions shown in Table 1 were obtained in the same manner as in Synthesis Example 2. Thereafter, HG, BCS and NMP are added to this solution so that the solvent mass ratio is HG: BCS: NMP = 30: 50: 20 and the SiO ₂ equivalent concentration is 3.5% by mass. It adjusted and the solution (P3-P10) of polysiloxane was obtained.

なお、表中の括弧内のモル数は、各アルコキシシランのモル数を示す。

The number of moles in parentheses in the table indicates the number of moles of each alkoxysilane.

<Synthesis Example 11>
Ethanol 661.75 g and TEOS 208 g were mixed, 126 g of water and 4.25 g of aqueous ammonia (concentration 28 mass%) were added at 40 ° C., and the mixture was stirred at 40 ° C. for 4 days to prepare a particle-containing solution. 435 g of HG was added to 500 g of the prepared silica particle-containing solution and concentrated to 300 g to prepare a silica particle-containing solution (Y1). The particle diameter was measured by a dynamic light scattering method. This particle diameter measurement method is described in Journal of Chemical Physics, Vol. 57, No. 11 (December 1972), page 4814. In the present invention, DLS- manufactured by Otsuka Electronics Co., Ltd. It was measured using 7000. As a result, the particle diameter of the silica particle-containing solution (Y1) was 20 nm.
To this solution (Y1), HG, added BCS and NMP, the mass ratio of the solvent HG: BCS: NMP = 30: 50: 20, and adjusted so that in terms of SiO ₂ concentration of 3.5 mass% As a result, a solution (Q1) containing silica particles was obtained.

<Examples 1-8>
With the composition shown in Table 2, the polysiloxane solutions (P2, P5 and P8) and the polysiloxane solution (P1) were mixed at room temperature to obtain liquid crystal aligning agents (L1 to L8).
Further, the polysiloxane solution (P2), the polysiloxane solution (P1), and the silica particle-containing solution (Q1) were mixed at room temperature to obtain a liquid crystal aligning agent (L9). Liquid crystal cells (elements) were prepared using the liquid crystal aligning agents (L1 to L9), and the liquid crystal alignment and voltage holding ratio were measured. The results are shown in Table 3.
In addition, the preparation method of a liquid crystal cell (element) and the measuring method of liquid crystal orientation and a voltage holding rate are shown below.

<Comparative Examples 1-8>
As shown in Table 2, instead of the liquid crystal aligning agents (L1 to L8), P1 to P4, P6, P7, P9, and P10 (M1 to M8) were used as they were, and the liquid crystal cell was formed in the same manner as in the example. The liquid crystal orientation and voltage holding ratio were measured.
The results are shown in Table 3.

[Creation of liquid crystal cell]
A film was formed on a glass substrate with a transparent electrode by a spin coating method using a liquid crystal aligning agent that had been pressure filtered through a membrane filter having a pore size of 0.5 μm. This substrate was dried on an 80 ° C. hot plate for 5 minutes and then baked in a hot air circulation oven at 180 ° C. for 60 minutes to form a liquid crystal alignment film having a thickness of 100 nm.
Prepare two substrates with a liquid crystal alignment film obtained as described above, spray a 6 μm spacer on the liquid crystal alignment film surface of one of the substrates, and then paste the liquid crystal alignment films so that they face each other. Created. Liquid crystal was injected into the empty cell to obtain a liquid crystal cell.
At that time, two types of liquid crystal were used, MLC-6608 (trade name) manufactured by Merck and MLC-7021-100 (trade name) manufactured by Merck.

[Liquid crystal orientation]
As a liquid crystal, MLC-7021-100 manufactured by Merck & Co., Ltd. was used to observe the liquid crystal cell obtained by the same method as [Creation of liquid crystal cell] with a polarizing microscope, and the alignment state of the liquid crystal was visually confirmed.
In the case of uniform vertical alignment without defects, it was marked as ◯, and in the case where alignment defects were observed and when no vertical alignment was observed, x.

[Voltage holding ratio]
A liquid crystal cell obtained using Merck MLC-6608 as the liquid crystal in the same manner as described above in [Creation of liquid crystal cell] was applied to Toyo Technica VHR-1 and applied with a 4V voltage. The voltage holding ratio (Voltage Holding Ratio: VHR) after 1667 ms was measured in an 80 ° C. constant temperature bath.

  As shown in Examples 1 to 9, the mixture of the polysiloxane (A) solution (P2, P5, P8) and the polysiloxane (B) solution (P1) is a comparative example 1 of the polysiloxane (A) solution alone. -7 and a polysiloxane (B) solution alone, the voltage holding ratio is higher than that of Comparative Example 8, very good vertical alignment is observed, and liquid crystal alignment is excellent.

[X-ray photoelectron spectroscopy]
The liquid crystal aligning agents L5 and P2 were pressure filtered through a membrane filter having a pore size of 0.5 μm, spin-coated on a silicon substrate [(100) surface], and placed on an 80 ° C. hot plate and dried for 5 minutes. Then, it baked for 60 minutes in a 180 degreeC hot-air circulation type oven, and obtained the coating film with a film thickness of 100 nm. About this coating film, the distribution of the element in the substrate direction from the surface of the film | membrane was analyzed using ESCA-3200 by Shimadzu Corporation. The results are shown in FIGS.
From this analysis result, the coating film obtained using P2 has a uniform carbon concentration in the film, whereas the liquid crystal alignment film obtained from the liquid crystal aligning agent (L5) of the present invention is near the surface layer. It was confirmed that a layer with a high carbon concentration was present.

The liquid crystal aligning agent of the present invention can provide a liquid crystal aligning film having the characteristics that the orientation is good and the voltage holding ratio is high in element driving at a low frequency under high temperature, and further a highly reliable liquid crystal display element. It is possible to provide.
Therefore, the liquid crystal alignment film of the present invention can be suitably used in various liquid crystal display elements, particularly in the vertical alignment type (VA). In addition, it can also be used in polarizing films, retardation films, and alignment films for viewing angle widening films.

It should be noted that the entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2006-060807 filed on March 7, 2006 is cited herein as the disclosure of the specification of the present invention. Incorporated.

Claims (12)

A liquid crystal aligning agent comprising the following polysiloxane (A), polysiloxane (B), and an organic solvent that dissolves these polysiloxanes.
Polysiloxane (A): polysiloxane obtained by polycondensation of alkoxysilane containing alkoxysilane represented by formula (1),

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B): polysiloxane obtained by polycondensation of alkoxysilane containing tetraalkoxysilane represented by the formula (2). However, the alkoxysilane represented by the formula (1) is not used in combination.

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.) A liquid crystal aligning agent comprising the following polysiloxane (A) solution and polysiloxane (B) solution.
Solution of polysiloxane (A): a solution of polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1) in an organic solvent,

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B) solution: A polysiloxane solution obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2) in an organic solvent. However, the alkoxysilane represented by the formula (1) is not used in combination.

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.) The liquid crystal aligning agent of Claim 1 or 2 whose polysiloxane (A) is a polysiloxane obtained by carrying out polycondensation using together at least 1 sort (s) of the alkoxysilane represented by Formula (3).

(R ⁴ is a hydrocarbon group having 1 to 5 carbon atoms, R ⁵ is a hydrogen atom or an organic group having 1 to 5 carbon atoms, and n represents an integer of 0 to 3) The liquid crystal alignment according to any one of claims 1 to 3, wherein the polysiloxane (B) is a polysiloxane obtained by polycondensation using at least one alkoxysilane represented by the formula (4). Agent.

(R ⁶ represents a hydrocarbon group having 1 to 5 carbon atoms, R ⁷ represents a hydrogen atom or an organic group having 1 to 6 carbon atoms, and m represents an integer of 1 or 2.)   The polysiloxane (A) is a polysiloxane obtained by polycondensation of an alkoxysilane represented by the formula (1) and tetraethoxysilane, and the polysiloxane (B) is a polysiloxane obtained from tetraethoxysilane. The liquid crystal aligning agent of Claim 1 or 2.   The polysiloxane (A) is a polysiloxane obtained by polycondensation of an alkoxysilane containing 2 to 30 mol% of an alkoxysilane represented by the formula (1). The liquid crystal aligning agent of one term.   The amount of silicon atoms in the polysiloxane (A) is 3 to 80 mol% with respect to the total amount of silicon atoms in the polysiloxane (A) and the polysiloxane (B). A liquid crystal aligning agent according to item.   The liquid crystal aligning film obtained using the liquid crystal aligning agent as described in any one of Claims 1 thru | or 7.   The liquid crystal display element which has a liquid crystal aligning film of Claim 8. The manufacturing method of the liquid crystal aligning agent characterized by including the process of mixing the solution of the following polysiloxane (A), and the solution of polysiloxane (B).
Solution of polysiloxane (A): a solution of polysiloxane obtained by polycondensation of an alkoxysilane containing an alkoxysilane represented by the formula (1) in an organic solvent,

(R ¹ is an organic group having 8 to 30 carbon atoms, and R ² represents a hydrocarbon group having 1 to 5 carbon atoms.)
Polysiloxane (B) solution: A polysiloxane solution obtained by polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2) in an organic solvent. However, the alkoxysilane represented by the formula (1) is not used in combination.

(R ³ represents a hydrocarbon group having 1 to 5 carbon atoms.)   The liquid crystal aligning agent production according to claim 10, wherein the solution of the polysiloxane (A) is a polysiloxane obtained by hydrolysis and polycondensation of an alkoxysilane containing the alkoxysilane represented by the formula (1). Method.   The liquid crystal alignment according to claim 10 or 11, wherein the solution of the polysiloxane (B) is a polysiloxane obtained by hydrolysis and polycondensation of an alkoxysilane containing a tetraalkoxysilane represented by the formula (2). Manufacturing method.

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