TW201504283A - Liquid crystal orienting agent containing polymer having blocked isocyanate group, liquid crystal orienting film, and liquid crystal display element - Google Patents

Abstract

Provided are: a liquid crystal orienting agent that can obtain a liquid crystal orienting film provided with a variety of functions and a variety of characteristics that are called for; a liquid crystal orienting film using same; and a liquid crystal display element. The liquid crystal orienting agent contains: a polymer having a blocked isocyanate group; and a compound having at least one functional group selected from an amino group and a hydroxyl group in the molecule.

Description

Liquid crystal alignment agent containing a polymer having a blocked isocyanate group, liquid crystal alignment film and liquid crystal display element

The present invention relates to a liquid crystal alignment element which can obtain a liquid crystal alignment film having various functions, a liquid crystal alignment agent containing a polymer having a blocked isocyanate group, a liquid crystal alignment film, and a liquid crystal alignment film obtained therefrom. .

Among the liquid crystal display elements, the liquid crystal alignment film serves to align the liquid crystal in a certain direction. Now, the main liquid crystal alignment film used in the industry will consist of a solution of polyimine precursor, polyglycolic acid (also known as polyamide acid), polyamidomate, or polyimine. A polyimide-based liquid crystal alignment agent is applied to a substrate and formed by film formation. Further, when the liquid crystal is aligned in parallel or obliquely with respect to the substrate surface, the surface extension treatment is further performed by rubbing after film formation. In addition, it is proposed to replace the friction processor by a method of anisotropic photochemical reaction such as polarized ultraviolet ray irradiation, and in recent years, it is reviewing industrialization.

In order to improve the display characteristics of such a liquid crystal display element, the structure and doping of poly-proline, polyphthalate or polyimine are changed. Polylysine, polylysine or polyimide having different characteristics; or means for adding an additive, etc., to improve liquid crystal alignment, electrical properties, etc., or to control a pretilt angle.

Technique for controlling pretilt angle by the structure of polyimine In the method of using a diamine having a side chain as a part of a polyimine raw material, the pretilt angle can be controlled by using the ratio of the diamine, and therefore, it is relatively easy to set the pretilt angle for the purpose, which can be increased. The means of pretilt angle is used. A side chain structure of a diamine which increases a pretilt angle of a liquid crystal, for example, a long-chain alkyl group or a fluoroalkyl group (for example, refer to Patent Document 1), a cyclic group or a combination of a cyclic group and an alkyl group (for example, refer to the patent literature) 2) A steroid skeleton (for example, refer to Patent Document 3) and the like are known.

In recent years, liquid crystal display elements have been widely used for large screens. In the case of a liquid crystal television or a high-definition mobile application (a display portion of a digital camera or a mobile phone), the substrate used is larger in size and the unevenness of the substrate step is larger than in the related art. In such a case, from the viewpoint of display characteristics, it is required to uniformly apply a liquid crystal alignment film to a large substrate or a step.

In addition, as the performance of the liquid crystal display element is increased, the area is increased, and the power saving of the display device is progressing, and the use is performed in various environments, the characteristics required for the liquid crystal alignment film are also severe. In particular, when a liquid crystal alignment agent is applied to a substrate, the problem that the takt time becomes long and precipitation or separation causes printing failure or image sticking due to accumulated charge (RDC) becomes a problem, and the conventional technology is difficult. Solve both at the same time.

Thus, in order to improve the desired characteristics, the polyimine-based liquid crystal alignment film is used as a part of raw materials, but It is sometimes impossible to freely use the desired diamine component due to its relationship with other characteristics.

In addition, the characteristics of polyimine are high mechanical strength, heat resistance, solvent resistance, so in addition to the liquid crystal alignment film, can be used as electrical. In the electronic field, protective materials and insulating materials are widely used. When used as such a material, the diamine component which is a raw material of polyimine is similarly improved. However, in the same manner, the desired diamine component cannot be used freely.

Further, it is desired to improve such a desired property, and it is not limited to the above-mentioned polyimine-based liquid crystal alignment film, and a liquid crystal alignment agent containing another polymer such as a (meth)acrylic polymer or a siloxane polymer is also expected to be improved. Kind of desired characteristics.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 2-282726

[Patent Document 2] Japanese Patent Laid-Open No. 3-179923

[Patent Document 3] Japanese Patent Laid-Open No. Hei 4-281427

The present invention relates to a liquid crystal alignment agent which can obtain a liquid crystal alignment film having various characteristics or various functions required, a liquid crystal alignment film obtained thereby, and a liquid crystal display element including the obtained liquid crystal alignment film.

The present invention is based on the following important techniques.

A liquid crystal alignment agent comprising a polymer having a blocked isocyanate group and a compound having at least one functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule.

2. The liquid crystal alignment agent of claim 1, wherein the polymer having a blocked isocyanate group is a polymer obtained by polymerizing a monomer represented below.

3. The liquid crystal alignment agent of the above 1, which has blocked isocyanic acid The ester-based polymer is a reaction of at least one type of polymer selected from the group consisting of a polyimide intermediate and a ruthenium imidized polymer of the polyimide precursor with a compound having a blocked isocyanate group. , formed when the liquid crystal alignment film is formed.

4. The liquid crystal alignment agent of the above 3, which comprises polyimine a precursor, a polymer selected from the group consisting of polyamidene obtained by ruthenium imidization of the polyimine precursor, a compound having a blocked isocyanate group, and an amine group in the molecule A compound having at least one functional group selected from the group consisting of hydroxyl groups.

5. The liquid crystal alignment agent according to the above 3 or 4, wherein the compound having a blocked isocyanate group is selected from the group consisting of (Z-1), (Z-2), (Z-3) and (Z-4) below. At least one of them, (In the formula (Z-1) to the formula (Z-4), R ² represents an organic group in a closed portion, and any one of B ₁ to B ₃ represents a methyl group, and the other two represent hydrogen, and B ₄ to B ₆ and B _{In the} same manner as B ₁ to B ₃ in ₇ to B ₉ , any one of them represents a methyl group, and the other two represent hydrogen.

6. The liquid crystal alignment agent according to any one of the above 1 to 5, wherein the compound having a functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule is 100% by mass based on the polymer having a blocked isocyanate group. It contains 5 mass% to 50 mass%.

7. The liquid crystal alignment agent according to any one of the above 1 to 6, wherein the compound having a functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule is represented by the following formula (2): (wherein R represents an amine group or a hydroxyl group, and Y represents an n-valent organic group).

A liquid crystal alignment film obtained by the liquid crystal alignment agent according to any one of the above 1 to 7.

A liquid crystal display element comprising the liquid crystal alignment film of the above 8.

According to the present invention, by modifying a polymer in a liquid crystal alignment agent by blocking a compound of a functional group having at least one selected from the group consisting of an amine group and a hydroxyl group in the molecule, it is possible to form a comparison by modifying the polymer in the liquid crystal alignment agent. A liquid crystal alignment agent that can freely improve liquid crystal alignment films of various characteristics.

[Formation of the Invention] <Polymer having a blocked isocyanate group>

In the present invention, the polymer having a blocked isocyanate group contained in the liquid crystal alignment agent may be in the case of containing a polymer having a blocked isocyanate group in the liquid crystal alignment agent (A), or in a stage of obtaining a liquid crystal alignment film. A case of any of the cases (B) having a polymer having a blocked isocyanate group formed. The following describes this.

Further, in the present invention, the blocked isocyanate group means, for example, a group represented by the following formula (2), and the isocyanate group (-NCO) is blocked by a suitable protecting group (R ² ) to block the isocyanate group. In the present invention, the blocked isocyanate group is heated and fired by the formation of the liquid crystal alignment film, and the protective group (block portion) is thermally dissociated to be separated from the reactive isocyanate group. The isocyanate group to be produced is subjected to a crosslinking reaction with a polymer constituting the liquid crystal alignment film or a compound having a functional group having at least one selected from the group consisting of an amine group and a hydroxyl group in the molecule.

(In the formula (2), R ² represents an organic group in the closed portion.)

(A) A case where a polymer having a blocked isocyanate group is contained in a liquid crystal alignment agent

In this case, the liquid crystal alignment agent of the present invention contains a polymer having a blocked isocyanate group and a compound having a functional group having at least one selected from an amine group and a hydroxyl group in the molecule (hereinafter also referred to as a functional monomer).

A polymer having a blocked isocyanate group can be obtained by producing a polymer using a raw material containing various polymers of a blocked isocyanate group. For example, when the polyimine precursor and the polyimine obtained by imidating the polyimine precursor are used as a polymer, any one of the tetracarboxylic dianhydride and the diamine of the raw material may be used. Both of them are obtained by using a blocked isocyanate group, which can be obtained by polymerizing a polyimine precursor to imidize the oxime. this In view of the ease of introducing the blocked isocyanate, it is preferred to use a diamine containing a blocked isocyanate group.

Further, in the case of other polymers such as a (meth)acrylic polymer or a polyoxyalkylene, the following acrylic polymer is exemplified.

<functional monomer>

The functional single system in the present invention refers to a compound which is introduced into the skeleton of the polymer via a blocked isocyanate group, and thus is a compound having a site (functional group) which reacts with an isocyanate group, that is, an amine group and/or a hydroxyl group.

The functional single system of the present invention has at least one group selected from an amine group and a hydroxyl group in the molecule, and is represented by the following formula.

(wherein R represents an amine group or a hydroxyl group, and Y represents an n-valent organic group.)

In the above formula, a specific example of Y when n is 2, for example, a divalent organic group represented by the following formulas (Y-1) to (Y-120). Among them, in order to obtain a good liquid crystal alignment property, a structure in which a highly linear diamine compound is used as a raw material is preferred. Such Y, for example, are (Y-7), (Y-10), (Y-11), (Y-12), (Y-13), (Y-21), ( Y-22), Y-23, Y-25, Y-26, Y-27, Y-42, Y-43, Y- 44), (Y-45), (Y-46), (Y-48), (Y-61), (Y-63), (Y-64), (Y-65), (Y-66) , (Y-67), (Y-68), (Y-69), (Y-70), (Y-71), (Y-78), (Y-79), (Y-80), ( Y-81), (Y-82), (Y-109), etc.

Further, as a liquid crystal alignment film for increasing the pretilt angle of liquid crystal In the case, a structure in which a side chain has a long-chain alkyl group (for example, an alkyl group having 10 or more carbon atoms), an aromatic ring, an aliphatic ring, a steroid skeleton, or a diamine compound having a structure as a raw material is preferable. Such Y, for example, are (Y-83), (Y-84), (Y-85), (Y-86), (Y-87), (Y-88), (Y-89), (Y -90), (Y-91), (Y-92), (Y-93), (Y-94), (Y-95), (Y-96), (Y-97), (Y-98) ), (Y-99), (Y-100), (Y-101), (Y-102), (Y-103), (Y-104), (Y-105), (Y-106), (Y-107), or (Y-108), etc., but are not limited thereto.

Moreover, when it is desired to improve the electrical characteristics of the liquid crystal display element, for example There are (Y-31), (Y-40), (Y-64), (Y-65), (Y-66), (Y-67), (Y-109), (Y-110), and the like. Further, when photoreactive properties are to be imparted to the liquid crystal alignment film, for example, (Y-17), (Y-18), (Y-111), (Y-112), (Y-113), (Y-114) , (Y-115), (Y-116), (Y-117), (Y-118), (Y-119), and the like.

In the compound represented by the above formula, a specific example of Y when n is 1, for example, a monovalent organic group represented by the following formula or [Y-1] to [Y-120] A structure in which a bonding bond is bonded to a hydrogen atom, etc., but is not limited thereto.

Further, in the compound represented by the above formula, a specific example of Y when n is 3 or more, for example, an organic group having a trivalent or higher value represented by the following formula or a hydrogen atom of [Y-1] to [Y-120] is detached. The latter structure and the like are not limited thereto. In the present specification, Me is a methyl group.

(B) a case where a polymer having a blocked isocyanate group is formed at a stage of obtaining a liquid crystal alignment film

In this case, the liquid crystal alignment agent of the present invention contains a polymer which forms a liquid crystal alignment film, a compound having a blocked isocyanate group (hereinafter simply referred to as a blocked isocyanate compound), and the above functional monomer.

Here, the polymer forming the liquid crystal alignment film means, in addition to the polyimine precursor and the polyimine obtained by subjecting the polyimine precursor to ruthenium imidization, for example, (meth)acrylic polymerization. , a siloxane polymer, and the like. Among them, from the viewpoint of easiness of introduction of a portion reactive with an isocyanate group, characteristics of a liquid crystal alignment film, and the like, it is preferred to use a polyimine precursor and a polyimide obtained by subjecting the polyimine precursor to ruthenium iodide. A polymer selected from at least one of the group consisting of quinone imines.

The polyimine precursor is obtained by reacting a tetracarboxylic acid derivative component with a diamine component to obtain a polyamic acid, and the polyamidene is obtained by subjecting the polyamic acid to ruthenium imidization.

Next, a polyimine precursor, a polyimine, and a compound having a blocked isocyanate group will be described.

<Polyimide precursor>

The polyimine precursor contained in the liquid crystal alignment agent of the present invention is a polyamic acid and/or a polyphthalate, and has a structural unit represented by the following formula (1).

In the above formula (1), R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Each of A ₁ and A _{2 is} independently a hydrogen atom or an alkyl group, an alkenyl group or an alkynyl group having 1 to 10 carbon atoms which may have a substituent.

In the formula (1), R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms. The polyphthalate increases the temperature at which the oxime imidization proceeds as the carbon number in the alkyl group increases. Therefore, R _{1 is} particularly preferably a methyl group from the viewpoint that heat is easily carried out by imidization.

In the formula (1), each of A ₁ and A _{2 is} independently a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group or an aliphatic ring group having 1 to 12 carbon atoms which may have a substituent. Specific examples of the above alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group and a decyl group. The alkenyl group, for example, has one or more CH-CH structures present in the above alkyl group substituted by a C=C structure, and more specifically, for example, a vinyl group, an allyl group, a 1-propenyl group, or an isopropylene group. A group, a 2-butenyl group, a 1,3-butadienyl group, a 2-pentenyl group, a 2-hexenyl group, a cyclopropenyl group, a cyclopentenyl group, a cyclohexenyl group or the like. The alkynyl group is, for example, a structure in which one or more CH ₂ -CH ₂ structures present in the alkyl group are substituted by a C≡C structure, and more specifically, for example, an ethynyl group, a 1-propynyl group, or a 2-propane group. Alkynyl and the like. Specific examples of the above aliphatic cyclic group include a cyclopentyl group, a cyclohexyl group, a dicyclohexyl group and the like.

The alkyl group, the alkenyl group, and the alkynyl group may have a substituent as long as the carbon number is from 1 to 10, and may further form a ring structure via a substituent. Further, the formation of a ring structure via a substituent means that the substituents are bonded to each other or a part of the substituent is bonded to a part of the parent skeleton to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organic oxy group, an organic thio group, an organic decyl group, a decyl group, an ester group, a thioester group, a phosphate group, a decyl group, Alkyl, alkenyl, alkynyl.

The halogen group of the substituent may, for example, be a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. The aryl group of the substituent is, for example, a phenyl group. This aryl group may be further substituted with the other substituents described above. The organooxy group of the substituent may, for example, be a structure represented by OR. The organothio group of the substituent, for example, a structure which can be represented by -SR. The organoalkylene group of the substituent may, for example, be a structure represented by -Si-(R) ₃ . The thiol group of the substituent may, for example, be a structure represented by -C(O)-R. The ester group of the substituent may be, for example, a structure represented by -C(O)OR or -OC(O)-R. The thioester group of the substituent may be, for example, a structure represented by -C(S)OR or -OC(S)-R.

The phosphate group of the substituent may be, for example, a structure represented by -OP(O)-(OR) ₂ . The amide group of the substituent may be represented, for example, by -C(O)NH ₂ or -C(O)NHR, -NHC(O)R, -C(O)N(R) ₂ , -NRC(O)R. structure. These R may be the same or different, and may, for example, be an alkyl group, an alkenyl group, an alkynyl group, an aryl group or the like. These R may be further substituted by the aforementioned substituents.

Specific examples of the organic oxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group and the like.

Specific examples of the organic sulfur group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group and the like.

Specific examples of the organic decyl group are a trimethyl decyl group, a triethyl decyl group, a tripropyl decyl group, a tributyl decyl group, a tripentyl decyl group, a trihexyl decyl group, a pentyl dimethyl decyl group, a hexyl group. Dimethyl decyl group and the like.

Specific examples of the mercapto group include a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a pentamidine group, an isovaleryl group, a benzamidine group and the like.

The alkyl group, the alkenyl group, the alkynyl group and the aryl group of the substituent are the same as those of the above-mentioned alkyl group, alkenyl group, alkynyl group and aryl group. Alkyl, alkene The base, alkynyl group, and aryl group may be further substituted with the other substituents described above.

In general, when a bulky structure is introduced, there is a possibility that the reactivity of the amine group or the liquid crystal alignment property is lowered, and A ₁ and A _{2 are more} preferably a hydrogen atom or a carbon number of 1 to 5 which may have a substituent. An alkyl group, particularly preferably a hydrogen atom, a methyl group or an ethyl group.

In the above formula (1), when X ₁ is a tetravalent organic group, the structure thereof is not particularly limited, and two or more kinds may be mixed. When a specific example of X ₁ is to be displayed, for example, X-1 to X-46 and the like shown below are available. Among them, in terms of monomer availability, X _{1 is} preferably X-1, X-2, X-3, X-4, X-5, X-6, X-8, X-16, X- 19. X-21, X-25, X-26, X-27, X-28 or X-32.

In the above formula, Y ₁ is a divalent organic group, and two or more kinds may be mixed. When the structure of the specific example of Y ₁ is to be displayed, for example, Y-1 to Y-106 shown below are not limited thereto. Among these, from the viewpoints of the reactivity of the diamine and the solubility of the polymer, it is more preferred to use Y-7, Y-8, Y-13, Y-18, Y-19, Y-42, Y- 43. A diamine of the structure of Y-45, Y-55, Y-59, Y-74, Y-78, Y-79, Y-80, Y-81, Y-82.

Polyimine precursor used in the liquid crystal alignment agent of the present invention Among them, a polyimine precursor which is suitable for a structure which undergoes a crosslinking reaction with a compound having a blocked isocyanate group is preferred. Specifically, a polyimide precursor having at least one of an amine group and a hydroxyl group is preferred. Moreover, in the polyamidene precursor polymer, there are many carboxylic acid groups, for the hair Since the compound having a blocked isocyanate group is highly reactive, it is preferred as the first aspect of the present invention.

Further, in the polyimine contained in the liquid crystal alignment agent of the present invention, the dehydration ring closure ratio of the valeric acid group is not necessarily 100%, and can be arbitrarily adjusted depending on the use or purpose.

<Method for producing polyimine]

When a polyamidene is obtained by using a polyamidene precursor of a polyimine precursor, a method of ruthenium imidating polylysine, for example, a hydrazine imidization in which a polyglycine solution is directly heated, The catalyst is added to the polyaminic acid solution to imidize the catalyst.

The temperature at which the polyaminic acid is thermally imidized in the solution is from 100 ° C to 400 ° C, preferably from 120 ° C to 250 ° C, and the water formed by the hydrazine imidization reaction is excluded from the system. It is preferred to carry out the thermal imidization at the same time.

The polyaminic acid catalyst oxime imidization is carried out by adding a basic catalyst and an acid anhydride to the polyamic acid solution, and stirring at -20 to 250 ° C, preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the prolyl group, and the amount of the anhydride is 1 to 50 moles of the amidate group, preferably 3 to 30 moles.

The basic catalyst used for the imidization of the above catalyst is, for example, pyridine, triethylamine, trimethylamine, tributylamine or trioctylamine. Among them, pyridine is preferred because it has moderate alkalinity for the reaction.

Examples of the acid anhydride used for the imidization of the catalyst oxime include acetic anhydride, trimellitic anhydride, and pyromellitic dianhydride. Which uses acetic anhydride In the case where the purification after the completion of the reaction becomes easy, it is preferred. The imidization ratio of the ruthenium imidized by the catalyst can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

<blocking isocyanate compound>

The blocked isocyanate compound in the present invention is not particularly limited as long as it is a compound having a blocked isocyanate group. The blocked isocyanate compound can be obtained, for example, by a compound having an isocyanate group in the molecule and using a suitable blocking agent.

The blocking agent is, for example, an alcohol such as methanol, ethanol, isopropanol, n-butanol, 2-ethylhexanol, 2-N,N-dimethylaminoethanol, 2-ethoxyethanol or cyclohexanol. Phenols such as phenols, o-nitrophenols, p-chlorophenols, o-, m- or p-cresols, decylamines such as ε-caprolactam, and acetone oxime , methyl ethyl ketone oxime, methyl isobutyl ketone oxime, cyclohexanone oxime, acetophenone oxime, benzophenone oxime, etc., pyrazole, 3,5-dimethylpyrazole, 3 a pyrazole such as a pyrazole such as methylpyrazole, a dodecanethiol or a thiol such as benzenethiol.

The blocked isocyanate compound is thermally decomposed in a closed portion at a high temperature of a temperature at which heating and firing is performed at the time of formation of a liquid crystal alignment film, and is crosslinked by an isocyanate group, but in a low temperature state in which the liquid crystal alignment agent is stored, It is preferred that the isocyanate group be crosslinked. In order to achieve such thermal reactivity, the temperature of the thermal dissociation of the blocked portion of the blocked isocyanate compound is very high compared to the storage of the liquid crystal alignment agent, for example, preferably from 50 ° C to 230 ° C, more preferably 100. °C~180°C.

Blocked isocyanate Particularly preferred is a blocked isocyanate compound having three or more blocked isocyanate groups in one molecule. This compound is obtained, for example, by the action of a suitable blocking agent as described above for a compound having three or more isocyanate groups in one molecule.

The compound having three or more blocked isocyanate groups in the above-mentioned one molecule is, for example, a specific example of a compound represented by the following formula (Z-1) to formula (Z-4).

(In the formula (Z-1) to the formula (Z-4), R ² represents an organic group in the closed portion.

In the formula (Z-3), any one of B ₁ to B ₃ represents a methyl group, and the other two represent hydrogen. In B ₄ to B ₆ and B ₇ to B ₉ , similarly to B ₁ to B ₃ , any one of them represents a methyl group, and the other two represent hydrogen. )

When the liquid crystal alignment agent of the present invention contains a blocked isocyanate compound, the blocked isocyanate compounds may be used alone or in combination of two or more.

Further, the blocked isocyanate compound is contained in the liquid crystal alignment agent in an amount of from 0.5 to 50% by mass, preferably from 5 to 40% by mass, based on at least one polymer selected from the group consisting of a polyimide and a polyimide. .

<Liquid alignment agent>

The liquid crystal alignment agent of the present invention contains a resin component for forming a liquid crystal alignment film of a resin film and an organic solvent for dissolving the resin component.

The liquid crystal alignment agent of the present invention contains the above-mentioned polymer having a blocked isocyanate group (hereinafter also referred to as a polymer of the present invention) as the above resin component.

All of the above resin components may be the polymer of the present invention, and other polymers other than the polymer of the present invention may be mixed. The content of the polymer of the present invention in the liquid crystal alignment agent is preferably 5% by mass or more, and more preferably 10% by mass or more.

Other polymers other than the polymer of the present invention include, for example, a polyimine precursor represented by the above formula (1) and/or a polyimide which is ruthenium imidized with a polyimide precursor.

The organic solvent contained in the liquid crystal alignment agent which dissolves the resin component is not particularly limited. Specific examples are N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, Dimethyl hydrazine, γ-butyrolactone, and the like. These organic solvents are good solvents for high solubility of the resin.

In addition to the above good solvents, in order to improve the coating of the liquid crystal alignment agent The uniformity of the cloth is preferably a weak solvent having a low solubility of the polymer. In the present invention, preferred weak solvents are, for example, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, diethyl Glycol monobutyl ether, ethyl carbitol acetate, ethylene glycol, ethylene glycol monohexyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1- Butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1- Monoethyl ether-2-acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, 4-hydroxy-4-methyl-2-pentanone, 2-(2-ethoxypropoxy)propyl Alcohol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate.

This weak solvent becomes a weak solvent having low solubility of the resin. The organic solvent contained in the solvent-based liquid crystal alignment agent is preferably 5 to 60% by mass, more preferably 10 to 50% by mass.

The concentration of the resin component in the liquid crystal alignment agent of the present invention can be appropriately adjusted in accordance with the film thickness of the liquid crystal alignment film to be obtained and the apparatus used for coating the liquid crystal alignment agent. The general resin concentration of the liquid crystal alignment agent is, for example, 1 to 20% by mass, preferably 2 to 10% by mass.

The liquid crystal alignment agent of the present invention may contain components other than the above. Examples thereof include a functional group-containing compound or an epoxy group-containing compound for improving the adhesion between the liquid crystal alignment film and the substrate, and a fluorine-based boundary for improving the planarization property of the coating film. A surfactant, a polyoxyn surfactant, a nonionic surfactant, and the like.

When the compound having a functional decane or a compound containing an epoxy group is contained, the content thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, even more preferably 1 to 20 parts by mass, based on 100 parts by mass of the resin component. ~10 parts by mass.

When the surfactant is contained, the content thereof is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of the resin component.

<Liquid alignment film and liquid crystal display element>

The liquid crystal alignment agent of the present invention is applied to a substrate, and after being fired, subjected to alignment treatment by rubbing treatment or light irradiation, or a part of vertical alignment use or the like, the alignment treatment can be used as a liquid crystal alignment film.

The method of applying the liquid crystal alignment agent of the present invention is not particularly limited, and is generally applied by screen printing, letterpress printing, offset printing, inkjet method, or the like. Other methods of using the coating liquid include a dipping method, a roll coating method, a slit coating method, a spinning method, and the like, and these can be used for the purpose. After being applied to the substrate by such a method, the solvent is evaporated by a heating means such as a hot plate to form a coating film.

The firing after the application of the liquid crystal alignment agent can be carried out at any temperature of 100 to 300 ° C, but is preferably 150 ° C to 250 ° C. For the firing, a hot plate, a heat cycle type oven, an IR (infrared) type oven, or the like can be used.

A raw silk cloth, a nylon cloth, a cotton cloth, or the like can be used for the rubbing treatment. The liquid crystal alignment film for vertical alignment is difficult to obtain a uniform alignment state by rubbing treatment. Therefore, when used as a liquid crystal alignment agent for vertical alignment, it is preferred not to use friction.

The liquid crystal cell of the present invention can be produced by a usual method, and the production method thereof is not particularly limited. In general, for example, a sealing agent may be applied to a glass substrate in which a liquid crystal alignment film is formed on at least one of the substrates, and the spacer may be dispersed at a constant pitch, and then the two substrates may be bonded to each other to cure the sealing agent. Empty cell, then injecting liquid crystal from the liquid crystal injection port under vacuum, sealing the injection port to form a liquid crystal cell; or dropping the liquid crystal onto the substrate on which the spacer is dispersed, and then bonding the two substrates to form a liquid crystal cell Wait. For the liquid crystal system, a fluorine-based liquid crystal or a cyano liquid crystal having positive and negative dielectric anisotropy can be used.

As described above, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can impart a large pretilt angle to the liquid crystal, and can be used as a liquid crystal alignment film for various purposes.

The invention is specifically illustrated by the following examples, but the invention is not limited to the examples.

[Examples]

The abbreviations used in the examples are as follows.

(methacrylic monomer)

MOI-BM: 2-(0-[1'-methylpropyleneamino]carboxyamino)ethyl methacrylate (manufactured by Showa Denko, karenz MOI-BM)

(tetracarboxylic dianhydride)

CBDA: 1,2,3,4-cyclobutane tetracarboxylic dianhydride

(diamine)

DBA: 3,5-diaminobenzoic acid

(compound with amine group)

(compound with hydroxyl group)

(compounds with blocked isocyanates)

TAKENATE B-882N (manufactured by Mitsui Chemicals, Inc.)

(Organic solvents)

NMP: N-methyl-2-pyrrolidone

BCS: Butyl Cyrus

DMF: N,N'-dimethylformamide

THF: tetrahydrofuran

(polymerization initiator)

AIBN: 2,2'-azobisisobutyronitrile

<Measurement of molecular weight of polymer>

The molecular weight of the polymer in the synthesis example was measured by a room temperature gel permeation chromatography (GPC) apparatus (SSC-7200, Shodex Co., Ltd. column (KD-803, KD-805) manufactured by Sensho Scientific Co., Ltd. as follows.

Column temperature: 50 ° C

Dissolution: DMF (additive: lithium bromide-hydrate (LiBr‧H ₂ O) is 30 mmol/L, phosphoric acid ‧ anhydrous crystal (o-phosphoric acid) is 30 mmol/L, tetrahydrofuran (THF) is 10 ml/L)

Flow rate: 1.0 mL/min

Standard sample for the production of calibration lines: TSK standard polyethylene oxide (weight average molecular weight of about 9,000, 150,000, 100,000, 30,000) manufactured by TOSOH Co., Ltd. and polyethylene glycol (peak peak molecular weight (Mp)) manufactured by Polymer Laboratories 12,000, 4,000, 1,000).

<Synthesis Example 1>

MOI-BM (15.56 g, 30.0 mmol) was dissolved in NMP (142.3 g), and a double diaphragm type pump was used for 6 minutes. After the bell was degassed, AIBN (0.246 g, 2.0 mmol) was added and degassed for 6 minutes. Then, the reaction was carried out at 60 ° C for 30 hours to obtain a polymer solution of methacrylate. To the polymer solution, BC (105.4 g) was added and diluted to 6 mass%, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal alignment agent (A). The polymer had a number average molecular weight of 14,000 and a weight average molecular weight of 55,000.

<Synthesis Example 2>

CBDA (3.88 g, 20.0 mmol) and DBA (3.04 g, 20.0 mol) were mixed in NMP (27.7 g), and reacted at room temperature for 20 hours to obtain a polyaminic acid solution. NMP (45.0 g) and BCS (34.6 g) were added to the polyamic acid solution to be diluted to 6 mass%, and the liquid crystal alignment agent (B) was obtained by stirring at room temperature for 5 hours. The polyamine had a number average molecular weight of 15,000 and a weight average molecular weight of 34,000.

<Example 1>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-1 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A1).

Further, after the liquid crystal cell was produced under the following conditions, the tilt angle was measured and the liquid crystal alignment property was evaluated.

[Production of liquid crystal cell (VA mode)]

The liquid crystal alignment agent (A1) obtained in Example 1 was spin-coated on the The ITO surface of the glass substrate with the transparent electrode formed of the ITO film was dried by a hot plate at 80 ° C for 90 seconds, and then fired in a hot air circulating oven at 200 ° C for 30 minutes to form a liquid crystal alignment film having a thickness of 100 nm.

Two sheets of the above-mentioned substrate were prepared, and a 6 μm bead spacer was spread on the liquid crystal alignment film of one of the substrates, and then a sealant (XN-1500T, manufactured by Kyoritsu Chemical Co., Ltd.) was printed thereon. Next, the liquid crystal alignment of the two substrates was pressed against the surface, and the sealant was thermally cured at 150 ° C for 105 minutes. A negative liquid crystal (manufactured by Merck, MLC-6608) was injected into the empty cell by a vacuum injection method to prepare a liquid crystal cell.

[Evaluation of pretilt angle]

The pretilt angle of the liquid crystal cell was measured by "AxoScan" manufactured by Axo Metrix Co., Ltd., and measured by a Mueller matrix.

"Evaluation of liquid crystal cell alignment"

After the liquid crystal cell was fabricated, the unit cell was observed by a polarizing microscope, and when the alignment was not performed, such as flow alignment or light transmission, it was evaluated that the alignment property was good.

<Example 2>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-2 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A2). In the same manner as in Example 1, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 3>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-3 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A3). In the same manner as in Example 1, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 4>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-4 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A4). In the same manner as in Example 1, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

[Production of liquid crystal cell (light alignment VA mode)]

The liquid crystal alignment agent (A4) obtained in Example 4 was spin-coated on the ITO surface of a glass substrate with a transparent electrode made of an ITO film, and dried by a hot plate at 80 ° C for 90 seconds, and then subjected to a hot air circulation of 200 ° C. The oven was fired for 30 minutes to form a liquid crystal alignment film having a film thickness of 100 nm.

On the substrate, a linear polarized light of 0 to 100 mJ of 313 nm having an irradiation intensity of 11.0 mW/cm ² was irradiated. The direction of the incident light is inclined by 40° with respect to the normal direction of the substrate. The linearly polarized UV is modulated by a 313 nm bandpass filter by passing ultraviolet light of a high pressure mercury lamp through a 313 nm bandpass filter.

Two sheets of the above-mentioned substrate were prepared, and a 6 μm bead spacer was spread on the liquid crystal alignment film of one of the substrates, and then a sealant (XN-1500T, manufactured by Kyoritsu Chemical Co., Ltd.) was printed thereon. Next, the liquid crystal of the two substrates is made The alignment direction was applied, and the projection direction of the optical axis of the linearly polarized UV of each substrate was pressed in an antiparallel manner, and the sealant was thermally cured at 150 ° C for 105 minutes. A positive liquid crystal (manufactured by Merck, MLC-6608) was injected into the empty cell by a vacuum injection method to prepare a liquid crystal cell.

[Evaluation of pretilt angle]

The pretilt angle was measured in the same manner as in Example 1.

"Confirmation of liquid crystal cell alignment"

After the liquid crystal cell is fabricated, the liquid crystal is driven while the AC voltage is AC=8 Vp-p, and the unit cell is observed by a polarizing microscope, and the misalignment such as no-flow alignment or light transmission is displayed, and the alignment is good, and the alignment is evaluated as good. .

<Example 5>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-5 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A5). In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 6>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-6 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A6). In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 7>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-7 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A7). In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 8>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-8 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A8). In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 9>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of DA-9 (30% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A9). After the liquid crystal cell was produced under the following conditions, the tilt angle was measured and the liquid crystal alignment property was evaluated.

[Production of liquid crystal cell (IPS mode)]

The liquid crystal alignment agent (A9) obtained in Example 9 was spin-coated on the ITO surface of a glass substrate with a transparent electrode made of an ITO film, and dried by a hot plate at 80 ° C for 90 seconds, and then subjected to a hot air circulation of 200 ° C. The oven was fired for 30 minutes to form a liquid crystal alignment film having a film thickness of 100 nm.

On the substrate, linear polarized light UV0 to 1000 mJ of 313 nm having an irradiation intensity of 11.0 mW/cm ^-2 was irradiated. The direction of the incident light is the normal direction of the substrate. The linearly polarized UV is modulated by a 313 nm band pass filter by passing ultraviolet light of a high pressure mercury lamp through a 313 nm band pass filter.

Two sheets of the above-mentioned substrate were prepared, and a 6 μm bead spacer was spread on the liquid crystal alignment film of one of the substrates, and then a sealant (XN-1500T, manufactured by Kyoritsu Chemical Co., Ltd.) was printed thereon. Next, the liquid crystals of the two substrates were aligned, and then the projection directions of the optical axes of the linearly polarized UVs of the respective substrates were pressed in an antiparallel manner, and the sealant was thermally cured at 150 ° C for 105 minutes. A positive liquid crystal (manufactured by Merck Co., Ltd., MLC-2014) was injected into the empty cell by a vacuum injection method to prepare a liquid crystal cell.

[Evaluation of pretilt angle]

The pretilt angle was measured in the same manner as in Example 1.

[Evaluation of liquid crystal cell alignment]

The alignment was evaluated in the same manner as in Example 1.

<Example 10>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of MA-1 (10% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A10). In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 11>

Addition to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1 HM-1 60 mg (30% by mass based on solid content) was dissolved by stirring at room temperature for 3 hours to prepare a liquid crystal alignment agent (A11). In the same manner as in Example 9, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Example 12>

With respect to 10.0 g of the liquid crystal alignment agent (A) obtained in Synthesis Example 1, 60 mg of HM-2 (30% by mass based on solid content) was added, and the mixture was stirred at room temperature for 3 hours to be dissolved to prepare a liquid crystal alignment agent (A12). In the same manner as in Example 9, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Comparative Example 1>

Using the liquid crystal alignment agent (A) obtained in Synthesis Example 1, a liquid crystal cell was produced in the same manner as in Example 1, and the alignment property was evaluated.

<Example 13>

With respect to 10.0 g of the liquid crystal alignment agent (B) obtained in Synthesis Example 2, 120 mg of DA-4 (20 mass % with respect to solid content) and TAKENATE B-882N (180 mg) (30 mass % with respect to solid content) were added. The mixture was stirred at room temperature for 3 hours to dissolve, and a liquid crystal alignment agent (B1) was prepared. In the same manner as in Example 4, after preparing a liquid crystal cell, the tilt angle was measured and the alignment property was evaluated.

<Comparative Example 2>

Using the liquid crystal alignment agent (B) obtained in Synthesis Example 2, a liquid crystal cell was produced in the same manner as in Example 1, and the alignment property was evaluated.

As described in Examples 1 to 3, it was confirmed that an amine compound having a vertical alignment energy can be used as a vertical alignment agent by adding a polymer having a vertical alignment energy to a polymer having a blocked isocyanate.

Further, as in Examples 4-8 and 10, it was confirmed that the photo-alignment film for the VA mode can be used by adding an amine compound having photoreactivity and vertical alignment energy.

Further, as in Examples 9, 11, and 12, it was confirmed that the photo-alignment film for horizontal alignment can be used as a photo-alignment film for horizontal alignment.

[Industrial availability]

The liquid crystal alignment agent of the present invention can relatively easily form a liquid crystal alignment film which improves various characteristics, and thus can be widely used in liquid crystal display elements in response to various requirements.

The entire disclosure of Japanese Patent Application No. 2013-73825, filed on Jan. 29,,,,,,,,,,,,,,,,

Claims (9)

A liquid crystal alignment agent comprising a polymer having a blocked isocyanate group and a compound having at least one functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule. The liquid crystal alignment agent of claim 1, wherein the polymer having a blocked isocyanate group is a polymer obtained by polymerizing a monomer represented below, The liquid crystal aligning agent of claim 1, wherein the polymer having a blocked isocyanate group is at least one selected from the group consisting of a polyimide precursor and a ruthenium imidized polymer of the polyimide precursor. The reaction of the polymer with a compound having a blocked isocyanate group is formed when a liquid crystal alignment film is formed. The liquid crystal alignment agent of claim 3, which comprises at least one selected from the group consisting of a polyimide precursor and a polyimine obtained by ruthenium imidating the polyimine precursor. And a compound having a blocked isocyanate group and a functional group having at least one selected from the group consisting of an amine group and a hydroxyl group in the molecule. The liquid crystal alignment agent of claim 3 or 4, wherein the compound having a blocked isocyanate group is selected from the group consisting of (Z-1), (Z-2), (Z-3) and (Z-4) At least one of them, (In the formula (Z-1) to the formula (Z-4), R ² represents an organic group in a closed portion, and any one of B ₁ to B ₃ represents a methyl group, and the other two represent hydrogen, and B ₄ to B ₆ and B _{In the} same manner as B ₁ to B ₃ in ₇ to B ₉ , any one of them represents a methyl group, and the other two represent hydrogen. The liquid crystal alignment agent according to any one of claims 1 to 5, wherein the compound having a functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule is 100% by mass based on the polymer having a blocked isocyanate group. It contains 5 mass% to 50 mass%. The liquid crystal alignment agent according to any one of claims 1 to 6, wherein the compound having a functional group selected from the group consisting of an amine group and a hydroxyl group in the molecule is represented by the following formula (2): (wherein R represents an amine group or a hydroxyl group, and Y represents an n-valent organic group). A liquid crystal alignment film obtained by the liquid crystal alignment agent according to any one of claims 1 to 7. A liquid crystal display element characterized by having the liquid crystal alignment film of claim 8.