TW201823305A - Photo-aligning liquid crystal aligning agents for photo-alignment method, photo-aligning film, liquid crystal display devices, and transverse electric field type liquid crystal display devices using the same using a reaction product containing tetracarboxylic dianhydride and diamine to achieve high adhesion strength with a sealant - Google Patents

Abstract

The present invention relates to a photo-aligning liquid crystal aligning agent comprising at least one of polyamic acid or a derivative thereof derived from a reaction product of a raw material monomer containing tetracarboxylic dianhydride and diamine. The photo-aligning liquid crystal aligning agent of the present invention is characterized by comprising a polymer (H) as at least one selected from the group consisting of compounds having a photoreactive structure, and comprising at least one reaction product of a raw material monomer of the compound represented by the following formula (I), and has a weight average molecular weight of 12,000 or less. By using the photo-aligning liquid crystal aligning agent of the present invention, a liquid crystal alignment film having high adhesion strength to a sealant can be formed; and by using the liquid crystal alignment film, a liquid crystal display element having high display quality and a transverse electric field type liquid crystal display can be manufactured.

Description

Liquid crystal alignment agent for photo alignment used in photo alignment method, and photo alignment film, liquid crystal display element and lateral electric field type liquid crystal display element using the same

The present invention relates to a liquid crystal alignment agent for photo alignment used in a photo alignment method, and a photo alignment film, a liquid crystal display element, and a lateral electric field type liquid crystal display element using the same.

Various display devices such as monitors for personal computers, LCD TVs, view finder for video cameras, projection displays, car navigation, smartphones, etc., and optoelectronics such as optical print heads, optical Fourier conversion elements, and light valves Optoelectronics-related elements, such as liquid crystal display elements that have been commercialized and are widely used today, are mainly display elements using nematic liquid crystals. The display modes of nematic liquid crystal display elements are widely known as a twisted nematic (TN) mode and a super twisted nematic (STN) mode. In recent years, in order to improve one of the problems with these modes, namely, the narrow viewing angle, a TN liquid crystal display element using an optical compensation film, and a multi-domain vertical alignment (MVA) technology using vertical alignment and protruding structures have been proposed. ) Mode, or In-Plane Switching (IPS) mode, Fringe Field Switching (FFS) mode, etc., and has been put into practical use.

The development of the technology of the liquid crystal display element is achieved not only by the improvement of these driving methods or the element structure, but also by the improvement of the constituent members used in the element. Among the constituent members used in the liquid crystal display element, especially the liquid crystal alignment film is one of important materials related to display quality. As the quality of the liquid crystal display element is improved, it is important to improve the performance of the alignment film.

The liquid crystal alignment film is formed of a liquid crystal alignment agent. At present, a liquid crystal alignment agent mainly used is a solution (varnish) obtained by dissolving a polyamic acid, a polyamic acid ester, or a polyimide in an organic solvent. After applying this solution on a substrate, a film is formed by a method such as heating to form a polyimide-based liquid crystal alignment film. After the film formation, an alignment process suitable for the display mode is performed as necessary.

The rubbing method which can easily perform large-area high-speed processing industrially is widely used as an alignment processing method. The rubbing method uses a cloth grafted with fibers such as nylon, rayon, and polyester to rub the surface of the liquid crystal alignment film in one direction, thereby obtaining a uniform alignment of the liquid crystal molecules. However, problems such as dust generation and static electricity caused by the friction method are pointed out. At present, the alignment processing method using friction is still used in the manufacturing steps of the liquid crystal display element, but in recent years, an alignment processing method that replaces it has been actively developed.

As the alignment processing method instead of the rubbing method, a light alignment processing method that irradiates light and performs alignment processing is attracting attention. A large number of alignment mechanisms such as a photodecomposition method, a photoisomerization method, a photodimerization method, and a photocrosslinking method have been proposed for the photoalignment treatment method (for example, refer to Non-Patent Document 1, Patent Document 1, and Patent Document 2). Compared with the rubbing method, the photo-alignment method has higher alignment uniformity and is a non-contact alignment treatment method. Therefore, it has the advantages of not damaging the film, reducing dust and static electricity, and causing the display failure of the liquid crystal display element.

Furthermore, in recent years, as the thickness of a liquid crystal display element is reduced and the display area is enlarged, a technique for narrowing a region where pixels are not formed on the outside (referred to as a frame region) on a substrate is being studied, so-called narrow frame. When the narrow frame is applied, it is necessary to reduce the coating area of the sealant to which two glass substrates are bonded, and therefore, there is a problem that the adhesion between the substrates is reduced. Furthermore, recently, in order to realize a further narrower frame, a technique for applying a liquid crystal alignment agent to one side of a glass substrate and applying a sealant to the formed liquid crystal alignment film is being studied. In this case, a decrease in the adhesion of the liquid crystal alignment film to the substrate and the sealant becomes a major problem. In particular, it is known that the adhesion between the interface of the liquid crystal alignment film and the sealant is weaker than the adhesion between the interface of the glass substrate and the sealant. In order to achieve a narrow frame, it is also required to increase the adhesion between the interface of the liquid crystal alignment film and the sealant. (See, for example, Patent Literature 3 and Patent Literature 4). [Prior Art Literature]

[Patent Literature] [Patent Literature 1] Japanese Patent Laid-Open No. 9-297313 [Patent Literature 2] Japanese Patent Laid-Open No. 10-251646 [Patent Literature 3] Japanese Patent Laid-Open No. 2009-258665 [Patent Literature 4] International Publication 2015/080186 [Non-patent literature]

[Non-Patent Document 1] "Liquid Crystals" Vol. 3, No. 4, 262, 1999

[Problems to be Solved by the Invention] An object of the present invention is to provide a liquid crystal alignment agent for optical alignment, which forms a liquid crystal alignment film having a high adhesion with a sealant and a liquid crystal display element with a high display quality. The present invention also provides a liquid crystal alignment film formed using the liquid crystal alignment agent for light alignment, and a liquid crystal display element including the liquid crystal alignment film. [Technical means to solve the problem]

As a result of diligent research, the inventors have found that the use of a diamine of the formula (I) having a plurality of hydroxyl groups as a raw material for a liquid crystal alignment agent for photo-alignment and adjusting the weight average molecular weight of the polymer can form and seal Liquid crystal alignment film with high adhesiveness. In addition, it was found that a liquid crystal alignment film that can provide a liquid crystal display element with high display quality can be formed, and the present invention has been completed. [Effect of the invention]

By using the liquid crystal alignment agent for photo-alignment of the present invention, a liquid crystal alignment film having a high adhesiveness with a sealant and providing a liquid crystal display element with high display quality can be formed.

The present invention includes the following. [1] A liquid crystal alignment agent for photo-alignment, which contains at least one polymer that is a reaction product derived from a raw material monomer containing a tetracarboxylic dianhydride and a diamine; the polymer includes the following polymer (H ); A raw material monomer for synthesizing the polymer (H) includes at least one kind of a compound having a photoreactive structure, and includes at least one kind of a compound represented by the following formula (I); and the weight of the polymer (H) The average molecular weight is 12,000 or less; Here, the polymer is selected from the group consisting of polyamic acid, polyimide, part of polyimide, polyamidate, polyamic acid-polyamidamine copolymer, and At least one of the group consisting of polyamidamine and imine. In formula (I), R is a structure represented by (a), (b), or (c); in formulas (a) and (b), R ⁰ is hydrogen or methyl.

[2] The liquid crystal alignment agent for photo-alignment according to item [1], comprising: the polymer (H); and other polymers used in combination with the polymer (H); The raw material monomer of the other polymer does not include a compound having a reactive structure, and does not include a compound represented by formula (I).

[3] The liquid crystal alignment agent for photo-alignment according to item [1], wherein the compound represented by the formula (I) is selected from the compounds represented by the following formulae (I-1) to (I-10) At least one of the groups.

[4] The liquid crystal alignment agent for photoalignment according to any one of [1] to [3], wherein the photoreactive structure of the raw material monomer is a photoisomerized structure.

[5] The liquid crystal alignment agent for photo-alignment according to item [4], wherein the tetracarboxylic dianhydride or diamine having a photoisomerization structure is at least a compound represented by the formulae (II) to (VI) One kind In formulae (II) to (V), R ² and R ³ are a monovalent organic group having -NH ₂ or a monovalent organic group having -CO-O-CO-, and in formula (IV), R ⁴ is A divalent organic group. In Formula (VI), R ^{5 is} independently an aromatic ring having -NH ₂ or -CO-O-CO-.

[6] The liquid crystal alignment agent for photoalignment according to item [5], wherein the tetracarboxylic dianhydride or diamine having a photoisomerization structure is selected from the group consisting of formula (II-1) and formula (II-2) , Formula (III-1), formula (III-2), formula (IV-1), formula (IV-2), formula (V-1) to formula (V-3), formula (VI-1), And at least one of the group of compounds represented by formula (VI-2); In the above formulas, a group in which the bonding position is not fixed on any carbon atom constituting the ring indicates that the bonding position on the ring is arbitrary; in formula (V-2), R ^{6 is} independently -CH ₃ , -OCH ₃ , -CF ₃ , or -COOCH ₃ , a is an integer of 0 to 2; In formula (V-3), ring A and ring B are each independently selected from monocyclic hydrocarbons and condensed polycyclic hydrocarbons. And at least one of heterocycles, R ¹¹ is a linear alkylene group having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N (CH ₃ ) CO-, or- CON (CH ₃ )-, R ¹² is a linear alkylene group having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N (CH ₃ ) CO-, or -CON In (CH ₃ )-, R ¹¹ and R ¹² , one or discontinuous two -CH ₂ -in the linear alkylene group may be substituted by -O-, and R ⁷ to R ¹⁰ are each independently -F,- CH ₃ , -OCH ₃ , -CF ₃ , or -OH, and b to e are each independently an integer of 0 to 4.

[7] The liquid crystal alignment agent for photo-alignment according to any one of the items [1] to [6], further comprising a compound selected from an alkenyl-substituted nadicarium imine compound and having a radical polymerizable unsaturated double bond At least one selected from the group consisting of a compound, an oxazine compound, an oxazoline compound, and an epoxy compound.

[8] The liquid crystal alignment agent for light alignment according to any one of the items [1] to [7], which is used for manufacturing a lateral electric field type liquid crystal display element.

[9] A liquid crystal alignment film formed of the liquid crystal alignment agent for light alignment according to any one of the items [1] to [8].

[10] A liquid crystal display element having the liquid crystal alignment film according to the item [9].

[11] A lateral electric field type liquid crystal display element including the liquid crystal alignment film according to [9].

The diamine represented by Formula (I) is demonstrated.

Specific examples of the diamine represented by the formula (I) used in the present invention are listed in the formulae (I-1) to (I-10). When used, these may be used in combination, or only one may be used. Among these compounds, when the adhesiveness at the interface between the liquid crystal alignment film and the sealant is improved, compounds of the formulae (I-5) to (I-8) are preferred, and formulae (I-5) or (I-6) are more preferred. )compound of.

These diamines represented by formula (I) can be synthesized by a method described in Japanese Patent No. 5642985.

The use amount of the diamine represented by the formula (I) is not particularly limited. When the polymer (H) having a photoreactive group, which will be described later, is produced, in order to exert the effect of improving the sealing adhesiveness, compared with the used diamine, The total amount of amine can be more than 5 mole%. In addition, from the viewpoint of preventing deterioration of contrast or afterimage of the liquid crystal display element, 20 mol% or less can be used. The used amount of the diamine represented by the formula (I) is preferably 5 mol% to 20 mol%, and more preferably 5 mol% to 10 mol%.

<Polymer (H)> The liquid crystal alignment agent for photo-alignment of this invention contains the polymer (H) demonstrated below. The raw material monomer for synthesizing the polymer (H) contains at least one kind of a compound having a photoreactive structure, and contains at least one kind of a compound represented by formula (I). The weight average molecular weight of the polymer (H) is 12,000 or less. The polymer (H) is at least one selected from the group consisting of polyamidic acid and its derivatives.

The term “polyamic acid derivative” refers to a component that is dissolved in a solvent when a liquid crystal alignment agent described later containing a solvent is made, and when the liquid crystal alignment agent is made into a liquid crystal alignment film, it can be formed to A component of a polyimide-based liquid crystal alignment film. Examples of such polyamidic acid derivatives include soluble polyamidoimide, polyamidate, and polyamidoamine. More specific examples include: 1) polyamidate All polyimide formed by dehydration ring-closure reaction of all amine groups and carboxyl groups, 2) partial polyimide formed by partial dehydration ring closure reaction, and 3) polycondensation product obtained by converting a carboxyl group of a polyamic acid into an ester Amidate, 4) a polyamic acid-polyamine copolymer obtained by substituting and reacting a part of an acid dianhydride contained in a tetracarboxylic dianhydride compound with an organic dicarboxylic acid, and 5) using A part of or all of the polyamide-polyamine copolymer is subjected to a dehydration ring-closing reaction. The polyamidic acid and its derivative may be one kind of polymer or two or more kinds. In addition, the polyphosphonic acid and its derivative may be a polymer having a structure of a reaction product of a tetracarboxylic dianhydride and a diamine, and may also contain the following reaction product: using other raw materials, It is obtained by a reaction other than the reaction of an anhydride and a diamine.

In the present invention, the photoreactive structure means, for example, a photoisomerized structure that isomerizes due to ultraviolet irradiation. A raw material monomer having a structure that causes a photoreaction by ultraviolet irradiation can be suitably used.

Examples of the monomer having the photo-isomerization structure include a tetracarboxylic dianhydride having a photo-isomerization structure or a diamine having a photo-isomerization structure, and is preferably selected from the following formula () having good photosensitivity II) to at least one of the group of compounds represented by formula (VI), and more preferably a compound represented by formula (V). In formulae (II) to (V), R ² and R ^{3 are} independently a monovalent organic group having -NH ₂ or a monovalent organic group having -CO-O-CO-, and in formula (IV), R ⁴ Is a divalent organic group, and in Formula (VI), R ^{5 is} independently an aromatic ring having -NH ₂ or -CO-O-CO-.

The photoisomerization structure can be incorporated into any of the main chain or side chain of the polyamic acid or a derivative thereof of the present invention, and by incorporating into the main chain, it can be preferably used for a liquid crystal of a lateral electric field method Display element.

As the material having the photoisomerization structure, a material selected from the following formula (II-1), formula (II-2), formula (III-1), formula (III-2), formula ( At least one of the groups of compounds represented by IV-1), formula (IV-2), formula (V-1) to formula (V-3), formula (VI-1), and formula (VI-2) One. In each of the above formulas, a group in which the bonding position is not fixed to any one of the carbon atoms constituting the ring indicates that the bonding position on the ring is arbitrary. In formula (V-2), R ^{6 is} independently -CH ₃ , -OCH ₃ , -CF ₃ , or -COOCH ₃ , and a is independently an integer of 0 to 2. In formula (V-3), ring A and ring B are each independently at least one selected from monocyclic hydrocarbons, condensed polycyclic hydrocarbons, and heterocyclic rings, and R ¹¹ is a linear alkylene group having 1 to 20 carbon atoms. , -COO-, -OCO-, -NHCO-, or -N (CH ₃ ) CO-, R ¹² is a linear alkylene group having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, or- In N (CH ₃ ) CO-, R ¹¹ and R ¹² , one or discontinuous two of -CH ₂ -in the linear alkylene group may be substituted by -O-, and R ⁷ to R ¹⁰ are each independently -F , -CH ₃ , -OCH ₃ , -CF ₃ , or -OH, and b to e are each independently an integer of 0 to 4.

The compounds represented by the formula (V-1), the formula (V-2), and the formula (VI-2) have particularly high photosensitivity, and therefore can be preferably used. Compounds in which the bonding position of the amine group in formula (V-2) and formula (VI-2) are para, and compounds of formula (V-2) where a = 0 are liquid crystal alignment of the polymer synthesized by using these It has high properties and can be used more preferably.

The tetracarboxylic dianhydride or diamine having a structure that can be isomerized by irradiation with ultraviolet rays represented by the formulae (II-1) to (VI-2) can be represented by the following formulae (II-1-1) to (VI-2-3) Specifically.

Among these, by formulae (V-1-1) to (V-3-8) as compounds containing a structure that can be isomerized by ultraviolet irradiation, light with higher sensitivity to ultraviolet irradiation can be obtained. Liquid crystal alignment agent for alignment. By formula (V-1-1), formula (V-2-1), formula (V-2-4) to formula (V-2-11) and formula (V-3-1) to formula (V -3-8) A compound containing a structure capable of causing isomerization by ultraviolet irradiation can be used to obtain a liquid crystal alignment agent for photo alignment that can align liquid crystal molecules more uniformly. By formulas (V-2-4) to (V-3-8) containing compounds capable of causing isomerization by irradiation with ultraviolet rays, it is possible to obtain a compound that can further reduce the coloring of the formed alignment film. Liquid crystal alignment agent for light alignment.

In the case where a tetracarboxylic dianhydride having no photoreactive structure (non-photosensitive) and a tetracarboxylic dianhydride having photoreactive structure (photosensitive) are used in combination, in order to prevent a decrease in the sensitivity of the liquid crystal alignment film to light The photosensitive tetracarboxylic dianhydride is preferably 30 mol% to 100 mol% with respect to the total amount of the tetracarboxylic dianhydride used as a raw material when producing the polyamic acid or a derivative thereof of the present invention. It is preferably 50 mol% to 100 mol%. In addition, in order to improve various characteristics such as sensitivity to light, electrical characteristics, and afterimage characteristics, two or more kinds of photosensitive tetracarboxylic dianhydrides may be used in combination.

In a form in which a diamine having no photoreactive structure (non-photosensitive) and a diamine having a photoreactive structure (photosensitive) are used in combination, in order to prevent a decrease in the sensitivity of the alignment film to light, the present invention is produced as compared with the present invention. The total amount of diamines used as a raw material in the case of polyamic acid or a derivative thereof is preferably 20 mol% to 100 mol%, and particularly preferably 50 mol% to 100 mol%. In addition, in order to improve various characteristics such as sensitivity to light and afterimage characteristics, two or more kinds of photosensitive diamines may be used in combination. As described above, the aspect of the present invention includes a case in which the total amount of the tetracarboxylic dianhydride is occupied by the non-photosensitive tetracarboxylic dianhydride, and even in this case, a minimum of 20 mol of the total amount of the diamine is required. Ear% is photosensitive diamine.

In order to improve various characteristics such as sensitivity to light and afterimage characteristics, a photosensitive tetracarboxylic dianhydride and a photosensitive diamine may be used in combination, or two or more of them may be used in combination.

As a raw material of the polymer (H), a known tetracarboxylic dianhydride or a derivative thereof and a diamine can be used in combination.

The well-known tetracarboxylic dianhydrides may belong to the aromatic system (including heteroaromatic ring systems) in which the dicarboxylic anhydride is directly bonded to the aromatic ring, and the aliphatic systems (including heterocyclic systems in which the dicarboxylic anhydride is not directly bonded to the aromatic ring). Ring system). For example, a tetracarboxylic dianhydride disclosed in Japanese Patent Laid-Open No. 2016-029447 or Japanese Patent Laid-Open No. 2016-041683 can be used.

The non-photosensitive diamine other than the compound represented by the formula (I) used for producing the liquid-crystal alignment agent for photo-alignment containing a polyamic acid or a derivative thereof of the present invention may be freely known from a non-photosensitive diamine. Choose from amines. For example, a diamine disclosed in Japanese Patent Laid-Open No. 2016-029447 or Japanese Patent Laid-Open No. 2016-041683 can be used.

In each of the diamines, a part of the diamine may be substituted with a monoamine in a range where the ratio of the monoamine to the diamine is 40 mol% or less. Such substitution can cause termination of the polymerization reaction when polyamic acid is produced, and can suppress further progress of the polymerization reaction. Moreover, the molecular weight of the obtained polymer (polyamic acid, polyamic acid ester, or polyimide) can be easily controlled, and for example, the coating characteristics of the liquid crystal alignment agent can be improved without impairing the effect of the present invention. As long as the effect of the present invention is not impaired, the diamine substituted with a monoamine may be one type, or two or more types. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, and n-deca Monoamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine.

The polyamidic acid or its derivative of the present invention may further contain a monoisocyanate compound in its monomer. By including a monoisocyanate compound in the monomer, the terminal of the obtained polyamic acid or its derivative is modified, and the molecular weight is adjusted. By using the terminal-modified polyamidic acid or a derivative thereof, for example, the coating characteristics of the liquid crystal alignment agent can be improved without impairing the effects of the present invention. From this viewpoint, the content of the monoisocyanate compound in the monomer is preferably 1 mol% to 10 mol% relative to the total amount of the diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthalene isocyanate.

The polyamidic acid and its derivatives of the present invention can be obtained by reacting a mixture of tetracarboxylic dianhydride and diamine in a solvent. In this synthesis reaction, in addition to the selection of raw materials, no special conditions are required, and the conditions in ordinary polyamic acid synthesis can be directly applied. The solvents used will be described later.

The liquid crystal alignment agent for photo-alignment of the present invention may further contain components other than the polyamic acid of the present invention and its derivative. The other components may be one type or two or more types. Examples of the other components include other polymers and compounds described later.

Examples of other polymers include polyamic acid, polyamino acid, or polyimide obtained by reacting a raw material monomer that does not have a photoisomerized structure and does not contain a diamine of formula (I). (Hereinafter, referred to as "other polyamic acid or its derivative"), polyester, polyamine, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene- Phenyl-cis-butene-diimine) derivatives, poly (meth) acrylates, and the like. It may be one type, or two or more types. Among these polymers, other polyamino acids or their derivatives and polysiloxanes are preferred, and other polyamino acids or their derivatives are more preferred.

The diamine used for synthesizing other polyamic acid or a derivative thereof preferably contains 30 mol% or more of the aromatic diamine with respect to all the diamines, and more preferably 50 mol% or more of the aromatic diamine.

The other polyamic acid or a derivative thereof can be synthesized according to a method described below as a method for synthesizing polyamic acid or a derivative thereof, which is an essential component of the liquid crystal alignment agent of the present invention.

As described above, the liquid crystal alignment agent for photo-alignment of the present invention is a liquid crystal alignment agent for photo-alignment containing at least one polymer obtained by reacting a raw material monomer, and the raw material monomer is selected from tetracarboxylic acid di At least one of the group consisting of an anhydride and a diamine has a photoreactive structure, and the diamine includes at least one of the compounds represented by the formula (1).

The liquid crystal alignment agent for photo-alignment of the present invention may contain at least two polymers. If the polymer having a photoreactive structure is [A] and the polymer having no photoreactive structure is [B], it is considered that the weight average molecular weight of [A] is controlled to A weight-average molecular weight smaller than [B]. In the process of coating and pre-drying a liquid crystal alignment agent containing a mixture of two polymers on a substrate, a photoreactive structure can be formed on the upper layer of the formed polymer film. [A] segregation, [B] segregation in the lower layer without a photoreactive structure. Therefore, the presence of the polymer [A] having a photoreactive structure on the surface of the alignment film becomes dominant, even if the polymer [A] having the photoreactive structure is based on the total amount of the polymers forming the alignment film. The content is small, and the alignment film formed by the liquid crystal alignment agent for photo-alignment of the present invention also exhibits high liquid crystal alignment.

As described above, it is known that in the process of forming a thin film using a liquid crystal alignment agent containing two polymers, a polymer having a small surface energy is separated into an upper layer, and a polymer having a large surface energy is separated into a lower layer. The confirmation of the layer separation of the alignment film can be performed by, for example, measuring the surface energy of the formed film and the value of the surface energy of the film formed of the liquid crystal alignment agent containing only the polymer [A]. Same or similar value.

As described above, in order to exhibit good photo-alignment, when the total amount of polymers included is set to 100, the content of [A] in the liquid crystal alignment agent for photo-alignment of the present invention needs to be 20% by weight or more. It is preferably 30% by weight or more, and more preferably 50% by weight or more. In addition, in order to keep the transmittance of the liquid crystal alignment film good, the content of [A] needs to be 90% by weight or less, preferably 70% by weight or less, and more preferably 50% by weight or less. Among them, the preferred content of [A] described herein is a guideline, and it may vary depending on the combination of tetracarboxylic dianhydride or diamine used in the raw material. In particular, when a raw material compound having an azobenzene structure is used, the content of [A] is set to be about 10 to 20% by weight less than the above ratio in order to maintain the permeability to be good.

Regarding the weight average molecular weight of the polymer, [A] is adjusted to 12,000 or less, and [B] is adjusted to 30,000 to 200,000, and preferably the molecular weight (Mw) of [A] is adjusted to 8,000 to 12,000, and the weight of [B] The molecular weight (Mw) is adjusted to 40,000 to 160,000, which can cause the layer separation described. The weight average molecular weight of a polymer can be adjusted according to the time which makes tetracarboxylic dianhydride react with a diamine, for example. A small amount of the reaction solution in the polymerization reaction can be taken, and the weight average molecular weight of the polymer contained in the reaction solution can be determined by the measurement of the gel permeation chromatography (GPC) method, and the reaction can be determined based on the measured value. end. In addition, a method is known in which a considerable amount of tetracarboxylic dianhydride and diamine are substituted with a monocarboxylic acid or a monoamine at the start of the reaction, thereby causing the termination of the polymerization reaction to control the weight average molecular weight.

The polysiloxane may further contain Japanese Patent Laid-Open No. 2009-036966, Japanese Patent Laid-Open No. 2010-185001, Japanese Patent Laid-Open No. 2011-102963, Japanese Patent Laid-Open No. 2011-253175, and Japanese Patent Laid-Open No. 2012-159825. International Publication 2008/044644, International Publication 2009/148099, International Publication 2010/074261, International Publication 2010/074264, International Publication 2010/126108, International Publication 2011/068123, International Publication 2011/068127, International Publication 2011/068128, International The polysiloxanes disclosed in 2012/115157, International Publication 2012/165354, and the like.

<Alkenyl-substituted Nadicadimidine compound> For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an alkenyl-substituted Nadicadamine compound. The alkenyl-substituted nadicarium imine compound may be used singly or in combination of two or more kinds. For the purpose, the content of the alkenyl-substituted nadic acid imidate compound is preferably 1% to 100% by weight, more preferably 1% to 70% by weight, and still more preferably relative to the polyamidic acid or a derivative thereof. 1% to 50% by weight.

The alkenyl-substituted nadicarium imine compound is preferably a compound that is soluble in a solvent that dissolves the polyamidic acid or a derivative thereof used in the present invention. Examples of such alkenyl-substituted nadic acid imine compounds include the alkenyl-substituted nadic acid compounds disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like. Examples of preferred alkenyl-substituted nadicariumimine compounds include bis {4- (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboxyfluorimide) phenyl} methane , N, N'-M-xylylene-bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboxyfluorenimine), N, N'-hexamethylene- Bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboxyfluorenimine).

<A compound having a radically polymerizable unsaturated double bond> For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain a compound having a radically polymerizable unsaturated double bond. . The compound having a radical polymerizable unsaturated double bond may be one kind of compound or two or more kinds of compounds. Furthermore, the compound having a radically polymerizable unsaturated double bond does not contain an alkenyl-substituted nadicarium imine compound. For the purpose, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1% to 100% by weight, and more preferably 1% to 70% by weight, relative to polyamic acid or a derivative thereof. More preferably, it is 1 to 50% by weight.

In addition, the ratio of the compound having a radical polymerizable unsaturated double bond to the alkenyl-substituted nadicarium imine compound is reduced in order to reduce the ion density of the liquid crystal display element, suppress the increase of the ion density over time, and further suppress The generation of an afterimage is preferably 0.1 to 10, and more preferably 0.5 to 5 in terms of a weight ratio of the compound / alkenyl-substituted nadicarium imine compound having a radically polymerizable unsaturated double bond.

Preferred examples of the compound having a radically polymerizable unsaturated double bond include compounds having a radically polymerizable unsaturated double bond disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like.

<Xazine Compound> For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an oxazine compound. The oxazine compound may be a single compound or two or more compounds. For the purpose, the content of the oxazine compound is preferably from 0.1% to 50% by weight, more preferably from 1% to 40% by weight, and still more preferably from 1% to 20% by weight based on the polyoxalic acid or its derivative. %.

The oxazine compound is preferably an oxazine compound that is soluble in a solvent that dissolves polyamic acid or a derivative thereof and that has ring-opening polymerizability. Preferred oxazine compounds include, for example, oxazine compounds represented by the formula (OX-3-1), (OX-3-9), or oxazine compounds disclosed in Japanese Patent Laid-Open No. 2013-242526.

<Oxazoline compound> For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an oxazoline compound. An oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one kind, or two or more kinds. For the purpose, the content of the oxazoline compound is preferably 0.1% to 50% by weight, more preferably 1% to 40% by weight, and still more preferably 1% to 20% by weight relative to polyamidic acid or a derivative thereof. weight%. Alternatively, when the oxazoline structure in the oxazoline compound is converted into an oxazoline, for the purpose described, the content of the oxazoline compound is preferably 0.1% to 5% by weight relative to polyamidic acid or a derivative thereof. 40% by weight.

Examples of the oxazoline compound include oxazoline compounds disclosed in Japanese Patent Laid-Open No. 2013-242526. Preferred oxazoline compounds include 1,3-bis (4,5-dihydro-2-oxazolyl) benzene.

<Epoxy Compound> For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an epoxy compound. The epoxy compound may be a single compound or two or more compounds. For the purpose, the content of the epoxy compound is preferably 0.1% to 50% by weight, more preferably 1% to 40% by weight, and still more preferably 1% to 20% by weight relative to polyamic acid or a derivative thereof. %.

Examples of the epoxy compound include those disclosed in Japanese Patent Laid-Open No. 2013-242526. Preferred epoxy compounds include: N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane , 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, (3,3 ', 4, 4'-diepoxy) dicyclohexyl.

In addition, for example, the liquid crystal alignment agent of the present invention may further contain various additives. Examples of the various additives include high-molecular compounds other than polyamic acid and its derivatives, and low-molecular compounds, and they can be selected and used according to their respective purposes.

For example, examples of the polymer compound include polymer compounds soluble in an organic solvent. From the viewpoint of controlling the electrical characteristics or alignment properties of the formed liquid crystal alignment film, it is preferable to add such a polymer compound to the liquid crystal alignment agent of the present invention. Examples of the polymer compound include polyamide, polyurethane, polyurea, polyester, polyepoxide, polyester polyol, silicone-modified polyurethane, and silicon. Ketone modified polyester.

In addition, as the low-molecular compound, for example, 1) when it is desired to improve the coatability, a surfactant suitable for the purpose may be listed, 2) when antistatic is required to be improved, an antistatic agent may be listed, and 3) when it is desired to improve the Examples of the adhesiveness include a silane coupling agent or a titanium-based coupling agent, and 4) Examples of a fluorene imidization catalyst when the fluorene imidization is performed at a low temperature.

Examples of the silane coupling agent include the silane coupling agents disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like. As a preferable silane coupling agent, 3-aminopropyltriethoxysilane is mentioned. Examples of the fluorene imidization catalyst include the fluorene imidization catalyst disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like.

The addition amount of the silane coupling agent is usually 0% to 20% by weight, and preferably 0.1% to 10% by weight, based on the total weight of the polyamic acid or its derivative.

The addition amount of the fluorene imidation catalyst is usually 0.01 equivalent to 5 equivalents, and preferably 0.05 equivalent to 3 equivalents with respect to the carbonyl group of the polyamic acid or a derivative thereof.

The addition amount of other additives varies depending on the use, but it is usually 0% to 100% by weight, and preferably 0.1% to 50% by weight, based on the total weight of the polyamic acid or its derivative.

Moreover, the liquid crystal aligning agent of this invention may contain a solvent from a viewpoint of the coating property of a liquid crystal aligning agent, or the adjustment of the density | concentration of the said polyamic acid or its derivative, for example. The solvent can be used without particular limitation as long as it has a capability of dissolving a polymer component. The solvent widely includes solvents generally used in the production steps or uses of polymer components such as polyamidic acid and soluble polyamimine, and can be appropriately selected according to the purpose of use. The solvent may be one kind or a mixed solvent of two or more kinds.

Examples of the solvent include a hydrophilic solvent of the polyamidic acid or a derivative thereof, or another solvent for the purpose of improving coating properties.

Examples of the aprotic polar organic solvent that is a lipophilic solvent with respect to polyamic acid or a derivative thereof include N-methyl-2-pyrrolidone, dimethyl imidazolidinone, and N-methylhexanone. Lactam, N-methylpropanamine, N, N-dimethylacetamide, dimethylmethylene, N, N-dimethylformamide, N, N-diethylformamide , Lactones such as diethylacetamide, γ-butyrolactone.

Examples of other solvents for the purpose of improving coating properties include alkyl lactate, 3-methyl-3-methoxybutanol, tetrahydronaphthalene, isophorone, phenylacetate, Ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monoalkyl ethers, propylene glycol monomethyl ether, propylene glycol monobutyl ether, etc. Monoalkyl ethers such as propylene glycol monoalkyl ether, diethyl malonate, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, ester compounds such as acetates, and ketone compounds such as diisobutanone .

Among these, the solvent is particularly preferably N-methyl-2-pyrrolidone, dimethylimidazolidone, γ-butyrolactone, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, or ethylene glycol monomethyl ether. , Propylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and diisobutyl ketone.

The concentration of the polyamidic acid in the liquid crystal alignment agent of the present invention is preferably from 0.1% by weight to 40% by weight. When this alignment agent is coated on a substrate, in order to adjust the film thickness, an operation of diluting the polyamic acid contained in the solvent may be required in advance.

The solid content concentration in the liquid crystal alignment agent of the present invention is not particularly limited, as long as the most suitable value is selected in combination with the various coating methods described below. In general, in order to suppress unevenness, pinholes, and the like during coating, it is preferably 0.1% to 30% by weight, and more preferably 1% to 10% by weight based on the weight of the varnish.

The viscosity of the liquid crystal alignment agent of the present invention differs in a preferable range depending on the coating method, the concentration of the polyamic acid or its derivative, the type of the polyamino acid or its derivative used, the type and ratio of the solvent. For example, when coating is performed using a printing press, it is 5 mPa · s to 100 mPa · s (more preferably 10 mPa · s to 80 mPa · s). When it is less than 5 mPa · s, it becomes difficult to obtain a sufficient film thickness, and when it exceeds 100 mPa · s, printing unevenness may increase. When coating is performed by spin coating, 5 mPa · s to 200 mPa · s (more preferably 10 mPa · s to 100 mPa · s) is suitable. When coating is performed using an inkjet coating device, 5 mPa · s to 50 mPa · s (more preferably 5 mPa · s to 20 mPa · s) is suitable. The viscosity of the liquid crystal alignment agent can be measured by a rotational viscosity measurement method, for example, using a rotational viscosity meter (TVE-20L type manufactured by Toki Sangyo) to measure (measurement temperature: 25 ° C).

<Liquid crystal alignment film> The liquid crystal alignment film of this invention is demonstrated in detail. The liquid crystal alignment film of the present invention is a film formed by heating the coating film of the liquid crystal alignment agent of the present invention. The liquid crystal alignment film of the present invention can be obtained by a general method for producing a liquid crystal alignment film from a liquid crystal alignment agent. For example, the liquid crystal alignment film of the present invention can be obtained by a step of forming a coating film of the liquid crystal alignment agent of the present invention, a step of heating and drying, and a step of heating and calcining. With respect to the liquid crystal alignment film of the present invention, an anisotropy can be imparted to the film obtained through the heating and drying step and the heating and calcining step, as necessary, as described later. Alternatively, anisotropy may be imparted by irradiating light after the coating step, heating and drying step, or irradiating light after the heating and calcining step, if necessary.

The coating film can be formed by applying the liquid crystal alignment agent of the present invention to a substrate in a liquid crystal display element in the same manner as in the production of a normal liquid crystal alignment film. The substrate may be provided with electrodes such as indium tin oxide (ITO), indium zinc oxide (In ₂ O ₃ -ZnO, IZO), indium gallium zinc oxide (In-Ga-ZnO ₄ , IGZO) electrodes, or the like. Substrates such as filters, glass, silicon nitride, acrylic, polycarbonate, and polyimide.

As a method of applying a liquid crystal alignment agent to a substrate, a spinner method, a printing method, a dipping method, a dropping method, an inkjet method, and the like are generally known. These methods can be similarly applied to the present invention.

The heating and drying step is generally known as a method of performing a heat treatment in an oven or an infrared oven, a method of performing a heat treatment on a hot plate, and the like. The heat-drying step is preferably carried out at a temperature within a range in which the solvent can be evaporated, and more preferably, it is carried out at a relatively low temperature relative to the temperature in the heating-sintering step. Specifically, the heating and drying temperature is preferably in the range of 30 ° C to 150 ° C, and more preferably in the range of 50 ° C to 120 ° C.

The heating sintering step may be performed under conditions required for the polyamidic acid or its derivative to exhibit a dehydration and ring-closure reaction. A method of heat-treating the coating film in an oven or an infrared oven, a method of heat-treating on a hot plate, and the like are generally known. These methods can be similarly applied to the present invention. Generally, it is preferably performed at a temperature of about 100 ° C to 300 ° C for 1 minute to 3 hours, more preferably 120 ° C to 280 ° C, and still more preferably 150 ° C to 250 ° C. In addition, multiple calcinations can be performed at different temperatures. A plurality of heating devices set to different temperatures may be used for heating and burning, or a heating device may be used to sequentially change to different temperatures for heating and burning. When the heating calcination is performed twice at different temperatures, it is preferably performed at 90 ° C to 180 ° C for the first time and at a temperature of 185 ° C or higher for the second time. In addition, the sintering can be performed by changing the temperature from a low temperature to a high temperature. When the temperature is changed and the sintering is performed, the initial temperature is preferably 90 ° C to 180 ° C. The final temperature is preferably 185 ° C to 300 ° C, and more preferably 190 ° C to 230 ° C.

In the method for forming a liquid crystal alignment film of the present invention, in order to align liquid crystals in one direction with respect to a horizontal direction and / or a vertical direction, a known formation method such as a rubbing method or a photo alignment method can be preferably used as the alignment film. Anisotropic methods.

A method for forming a liquid crystal alignment film of the present invention using a photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method can be formed by heating and drying the coating film, and then applying anisotropy to the coating film by irradiating the linearly polarized light or no polarization of the radiation, and heating the film. Simmer. Alternatively, the coating film can be formed by heating and drying the coating film, and then heating and sintering, and then irradiating the linearly polarized light or non-polarized light of the radiation. In terms of alignment, it is preferable to perform a radiation irradiation step before the heating and sintering step.

Furthermore, in order to improve the liquid crystal alignment ability of the liquid crystal alignment film, linearly polarized light or non-polarized light may be irradiated while heating the coating film. The radiation may be performed in the step of heating and drying the coating film, or in the step of heating and sintering the coating film, or may be performed between the step of heating and drying and the step of heating and sintering. The heating and drying temperature in this step is preferably in the range of 30 ° C to 150 ° C, and more preferably in the range of 50 ° C to 120 ° C. The heating and calcining temperature in this step is preferably in the range of 30 ° C to 300 ° C, and more preferably in the range of 50 ° C to 250 ° C.

As the radiation, ultraviolet rays or visible light including, for example, light having a wavelength of 150 to 800 nm can be used, and ultraviolet rays including light of 300 to 400 nm are preferred. Alternatively, linearly polarized or unpolarized light can be used. These lights are not particularly limited as long as they can impart liquid crystal alignment ability to the coating film, and when it is desired to exhibit strong alignment restricting force on the liquid crystal, linearly polarized light is preferred.

The liquid crystal alignment film of the present invention can exhibit high liquid crystal alignment ability even under low-energy light irradiation. The irradiation amount of the linearly polarized light in the radiation irradiation step is preferably 0.05 J / cm ² to 20 J / cm ² , and more preferably 0.5 J / cm ² to 10 J / cm ² . The wavelength of linearly polarized light is preferably 200 nm to 400 nm, and more preferably 300 nm to 400 nm. The irradiation angle of the linearly polarized light on the film surface is not particularly limited. When a strong alignment limiting force is intended to be applied to the liquid crystal, it is preferable to be as perpendicular to the film surface as possible from the viewpoint of shortening the alignment processing time. In addition, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating the linearly polarized light.

When the pretilt angle is to be expressed, the light irradiated to the film may be linearly polarized light or unpolarized light as described above. When the pretilt angle is to be expressed, the irradiation amount of light irradiated to the film is preferably 0.05 J / cm ² to 20 J / cm ² , particularly preferably 0.5 J / cm ² to 10 J / cm ² , and the wavelength thereof is preferably 250 nm. ～ 400 nm, particularly preferably 300 nm to 380 nm. When the pretilt angle is to be expressed, the irradiation angle of the light irradiated to the film with respect to the surface of the film is not particularly limited, and from the viewpoint of shortening the alignment processing time, it is preferably 30 degrees to 60 degrees.

In the light source used in the step of radiating linearly polarized or unpolarized light, ultra-high pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, deep ultraviolet lamps, halogen lamps, metal halide lamps, and high power can be used without limitation Metal halide lamps, xenon lamps, mercury xenon lamps, excimer lamps, KrF excimer lasers, fluorescent lamps, light emitting diode (LED) lamps, sodium lamps, microwave excited electrodeless lamps, and the like.

The liquid crystal alignment film of the present invention can be preferably obtained by a method which further includes steps other than the above steps. For example, although the liquid crystal alignment film of the present invention does not require the step of cleaning the film after scorch or radiation irradiation with a cleaning solution as a necessary step, a cleaning step may be provided according to the conditions of other steps.

Examples of the cleaning method using a cleaning liquid include brush cleaning, spraying, steam cleaning, and ultrasonic cleaning. These methods can be performed individually or in combination. As the cleaning solution, pure water or various alcohols such as methanol, ethanol, isopropanol, aromatic hydrocarbons such as benzene, toluene, and xylene, halogen-based solvents such as dichloromethane, acetone, methyl ethyl ketone, and the like can be used. Ketones are not limited to these cleaning solutions. Of course, as these cleaning liquids, a sufficiently purified cleaning liquid with few impurities can be used. Such a cleaning method can also be applied to the cleaning step when the liquid crystal alignment film of the present invention is formed.

In order to improve the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, an annealing process using heat or light may be used before and after the heating and calcining step, before and after the rubbing step, or before and after irradiation with polarized or unpolarized radiation. In this annealing treatment, the annealing temperature is 30 ° C to 180 ° C, preferably 50 ° C to 150 ° C, and the time is preferably 1 minute to 2 hours. Examples of the annealing light used for the annealing process include a UV lamp, a fluorescent lamp, and an LED lamp. The irradiation amount of light is preferably 0.3 J / cm ² to 10 J / cm ² .

The thickness of the liquid crystal alignment film of the present invention is not particularly limited, but it is preferably 10 nm to 300 nm, and more preferably 30 nm to 150 nm. The film thickness of the liquid crystal alignment film of the present invention can be measured by a known film thickness measuring device such as a step meter or an ellipsometer.

The liquid crystal alignment film of the present invention is characterized by having a particularly large alignment anisotropy. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in Japanese Patent Laid-Open No. 2005-275364 and the like. In addition, as shown in the following examples, the evaluation may be performed by a method using ellipsometry. In detail, a retardation value of a liquid crystal alignment film can be measured using a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of alignment of the polymer backbone. That is, a film having a large retardation value has a large degree of alignment, and when used as a liquid crystal alignment film, an alignment film having greater anisotropy is considered to have a large alignment limiting force for a liquid crystal composition.

The liquid crystal alignment film of the present invention can be preferably used for a liquid crystal display element of a lateral electric field method. When used for a liquid crystal display element of a lateral electric field method, the smaller the Pt angle and the higher the liquid crystal alignment ability, the higher the black display level in the dark state and the higher the contrast. The Pt angle is preferably 0.1 ° or less.

The liquid crystal alignment film of the present invention can be used for alignment control of liquid crystal compositions for liquid crystal displays such as smart phones, input boards, car monitors, and televisions. In addition to the alignment of liquid crystal compositions for liquid crystal displays, it can also be used for alignment control of optical compensation materials or all other liquid crystal materials. In addition, since the alignment film of the present invention has large anisotropy, it can be used alone as an optical compensation material.

<Liquid crystal display element> The liquid crystal display element of this invention is demonstrated in detail. The present invention provides a liquid crystal display element including a pair of substrates disposed opposite to each other, an electrode formed on one or both of the opposing surfaces of the pair of substrates, and a pair of each formed on the pair of substrates. The liquid crystal alignment film on the surface and the liquid crystal layer formed between the pair of substrates, and the liquid crystal alignment film is an alignment film of the present invention.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such an electrode include ITO and a vapor-deposited film of a metal. The electrode may be formed on the entire surface of one surface of the substrate, or may be formed into a desired shape, for example, patterned. Examples of the desired shape of the electrode include a comb shape and a zigzag structure. The electrode may be formed on one of a pair of substrates, or may be formed on two substrates. The form of the electrodes varies depending on the type of liquid crystal display element. For example, in the case of an IPS-type liquid crystal display element, the electrodes are arranged on one of the pair of substrates. In the case of other liquid crystal display elements, the electrodes are arranged. On both the pair of substrates. The liquid crystal alignment film is formed on the substrate or electrode.

The liquid crystal layer is formed in such a manner that a liquid crystal composition is sandwiched by the pair of substrates facing each other with a liquid crystal alignment film formed thereon. In the formation of the liquid crystal layer, if necessary, a spacer such as fine particles or a resin sheet that is interposed between the pair of substrates and forms an appropriate interval may be used.

As a method for forming the liquid crystal layer, for example, a vacuum injection method or a liquid crystal drip (ODF) method can be used. As a sealing agent for the adhesion | attachment of a board | substrate, a UV hardening type or a thermosetting type sealing agent can be used, for example. For printing of the sealant, for example, a screen printing method can be used.

The liquid crystal composition is not particularly limited, and various liquid crystal compositions having a positive or negative dielectric constant anisotropy can be used. Preferred liquid crystal compositions having a positive dielectric anisotropy include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent No. Hei 5-501735, Japanese Patent No. 8-157826, Japanese Patent No. 8-231960, and Japan Patent JP-A 9-241644 (EP885272A1), Japanese Patent JP-A 9-302346 (EP806466A1), Japanese Patent JP-A 8-199168 (EP722998A1), Japanese Patent JP-A 9-235552, Japanese Patent JP-A 9-255956, and Japanese Patent JP-A-9-241643 (EP885271A1), JP-A 10-204016 (EP844229A1), JP-A 10-204436, JP-A 10-231482, JP-A 2000-087040, JP-A 2001-2001 The liquid crystal composition disclosed in 48822 and the like.

Preferred examples of the liquid crystal composition having the negative dielectric constant anisotropy include Japanese Patent Laid-Open No. Sho 57-114532, Japanese Patent Laid-Open No. 2-4725, Japanese Patent Laid-Open No. 4-224885, and Japanese Patent JP-A-8-40953, JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10 10-236992, Japanese Patent Laid-Open No. 10-236993, Japanese Patent Laid-Open No. 10-236994, Japanese Patent Laid-Open No. 10-237000, Japanese Patent Laid-Open No. 10-237004, Japanese Patent Laid-Open No. 10-237024, Japanese Patent Laid-Open No. 10- 237035, Japanese Patent Laid-Open No. 10-237075, Japanese Patent Laid-Open No. 10-237076, Japanese Patent Laid-Open No. 10-237448 (EP967261A1), Japanese Patent Laid-Open No. 10-287874, Japanese Patent Laid-Open No. 10-287875, Japanese Patent Laid-Open No. 10 -291945, Japanese Patent Laid-Open No. 11-029581, Japanese Patent Laid-Open No. 11-080049, Japanese Patent Laid-Open No. 2000-256307, Japanese Patent Laid-Open No. 2001-019965, Japanese Patent Laid-Open No. 2001-072626, Japan Japanese Patent Laid-Open No. 2001-192657, Japanese Patent Laid-Open No. 2010-037428, International Publication No. 2011/024666, International Publication No. 2010/072370, Japanese Patent No. 2010-537010, Japanese Patent No. 2012-077201, Japanese Patent No. 2009-084362 The liquid crystal composition disclosed in et al. Even if one or more optically active compounds are added to a liquid crystal composition having a positive or negative dielectric constant anisotropy for use, there is no effect.

In addition, for example, from the viewpoint of improving the alignment property, an additive may be further added to the liquid crystal composition used in the liquid crystal display element of the present invention, for example. Such additives are photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, pigments, defoamers, polymerization initiators, polymerization inhibitors, and the like. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, pigments, defoamers, polymerization initiators, and polymerization inhibitors include the oxazine compounds disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like .

In order to be suitable for a liquid crystal display device having a polymer sustained alignment (PSA) mode, a polymerizable compound may be mixed in the liquid crystal composition. Preferred examples of the polymerizable compound are acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxetane, oxetane), vinyl ketone, etc. A compound having a polymerizable group. Preferred compounds include those disclosed in Japanese Patent Laid-Open No. 2013-242526 and the like.

Hereinafter, the present invention will be described by way of examples. The evaluation methods and compounds used in the examples are as follows.

<Evaluation method> 1. Weight-average molecular weight (Mw) The weight-average molecular weight of polyamic acid was determined by using a 2695 separation module and a 2414 differential refractometer (manufactured by Waters) and using the GPC method. The measurement was then performed in terms of polystyrene. Using a mixed solution of phosphoric acid-dimethylformamide (DMF) (phosphoric acid / DMF = 0.6 / 100: weight ratio), the obtained polyamic acid was adjusted so that the polyamic acid concentration became about 2% by weight. Dilute. HSPgel RT MB-M (manufactured by Waters) was used for the column, and the mixed solution was used as a developing agent, and the measurement was performed under conditions of a column temperature of 50 ° C and a flow rate of 0.40 mL / min. As the standard polystyrene, TSK standard polystyrene manufactured by Tosoh Co., Ltd. was used.

2. Sealing Adhesion For the samples for measuring sealing adhesion described later, the ends of the upper and lower substrates are fixed to a desktop precision universal testing machine AGS-X 500N manufactured by Shimadzu Corporation, and are pressed in from the upper part of the center of the substrate to measure peeling. Pressure (N). Then, the sealing adhesiveness was evaluated using a value obtained by normalizing the pressure (N) with the area (cm ² ) estimated from the diameter of the measured sealant. When it is 75 N / cm ² or more, it can be said that the sealing adhesion is good.

3. Contrast The contrast of the liquid crystal element described later was evaluated using a luminance meter (Yokogawa 3298F). A liquid crystal display element was placed under a crossed Nicols polarizing microscope, and the minimum brightness was measured as the black brightness. Next, an arbitrary rectangular wave voltage was applied to the device, and the maximum brightness was measured as white brightness. The value of this white brightness / black brightness is used as a contrast. When it is 3,500 or more, it is judged that it is good.

4. Alternating current (AC) residual image measurement The brightness-voltage characteristics (B-V characteristics) of the liquid crystal display element described later were measured. Let this be a brightness-voltage characteristic before stress: B (front). Next, after applying an alternating current of 4.5 V and 60 Hz to the device for 20 minutes, a short circuit was performed for 1 second, and then the luminance-voltage characteristic (B-V characteristic) was measured again. Let this be a brightness-voltage characteristic after stress: B (back). Based on these values, the following formula is used to estimate the luminance change rate ΔB (%). ΔB (%) = [B (rear) -B (front)] / B (front) (Formula AC1) These measurements are performed with reference to International Publication No. 2000/43833. It can be said that the smaller the value of ΔB (%) in the voltage of 0.75 V is, the more the generation of AC afterimage can be suppressed, and it is preferably 3.0% or less.

＜ Diamine ＞

＜ Tetracarboxylic dianhydride ＞

<Solvent> NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)

[Synthesis example 1, synthesis of varnish 1] Synthesis of varnish A with polymer (H) Into a 100 mL three-necked flask equipped with a stirring blade, a nitrogen introduction tube, and a thermometer, it was placed in the place of formula (V-2-1) Compound (1.8295 g, 8.62 mmol) and compound (0.2781 g, 0.96 mmol) represented by formula (I-5), and NMP (64.0 g) was added. The solution was cooled to 5 ° C, and a compound represented by the formula (AH-1) (3.8924 g, 9.57 mmol) was added thereto. The solution was stirred for 8 hours while the temperature of the solution was maintained at 5 ° C. BC (30.0 g) was added thereto, and the mixture was heated and stirred at 60 ° C until the viscosity of the solution became 10 mPa · s, thereby obtaining a varnish 1 having a polymer concentration of 6 wt%. The average molecular weight of the polymer contained in this varnish was 12,000.

[Synthesis example 2 to synthesis example 16, synthesis of varnish 2 to varnish 16] In addition to changing diamine and tetracarboxylic dianhydride, varnish 2 to polymer solid content concentration of 6% by weight was prepared according to Synthesis Example 1. Varnish 16. Table 1 shows the weight average molecular weights of the diamine and tetracarboxylic dianhydride used and the obtained polymer. The results of Synthesis Example 1 are also revealed again. The numbers in [] are expressed in terms of mol% with respect to the respective usage amounts of all raw materials.

Table 1

[Synthesis example 17 to synthesis example 21, synthesis of varnish 17 to varnish 21] Synthesis of varnish B without polymer (H) changed diamine and tetracarboxylic dianhydride, and polymerization was prepared according to Synthesis Example 1 The varnish 17 to varnish 21 having a solid content concentration of 6% by weight. Table 2 shows the weight average molecular weight of the diamine and tetracarboxylic dianhydride used and the polymer obtained. The numbers in [] are expressed in terms of mol% with respect to the respective usage amounts of all raw materials.

Table 2

[Comparative example 1 to comparative example 3, synthesis of varnish ratio 1 to varnish ratio 3] In addition to changing the diamine and tetracarboxylic dianhydride, a varnish having a polymer solid content concentration of 6% by weight was prepared according to Synthesis Example 1. Ratio 1 to varnish ratio 3. Table 3 shows the weight average molecular weight of the diamine and tetracarboxylic dianhydride used and the polymer obtained. The numbers in [] are expressed in terms of mol% with respect to the respective usage amounts of all raw materials.

table 3

[Example 1] Preparation of liquid crystal alignment agent for optical alignment, production of liquid crystal cells, production of samples for measuring sealing tightness, observation of cells, and evaluation of sealing tightness To a 50 mL eggplant type equipped with a stirring blade and a nitrogen introduction tube In a flask, 3.0 g of the varnish 1 synthesized in Synthesis Example 1 and 7.0 g of the varnish 17 synthesized in Synthesis Example 17 were weighed, and 5.0 g of NMP and 5.0 g of BC were added thereto. After stirring at room temperature for 2 hours, a liquid crystal alignment agent 1 having a polymer concentration of 3 wt% was obtained. This liquid crystal alignment agent 1 was coated on a raw glass substrate by a spinner method (2,000 rpm, 15 seconds). After coating, the substrate was heated at 80 ° C for 3 minutes to evaporate the solvent. Then, using Multi-Light ML-501C / B manufactured by Oxtail Motor Co., Ltd., the polarized light was passed from a direction perpendicular to the substrate. The panel is irradiated with linear polarized light. The exposure energy at this time was measured using a UV cumulative light meter UIT-150 (light receiver: UVD-S365) manufactured by Oxtail Motor Co., Ltd. to measure the light amount to be 0.8 J / cm ² ± 0.1 J / at a wavelength of 365 nm. cm ² to adjust the exposure time. The sintering process was performed at 230 ° C for 20 minutes to form a film having a film thickness of approximately 100 nm. Two substrates were prepared, and a 4 μm bead spacer was spread on the liquid crystal alignment film surface of one of the substrates, and then dropped onto an alignment film forming a sealant (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.). Then, the liquid crystal alignment film surface of the other substrate was placed inside, and the overlapping width of the substrates was set to 1 cm. At this time, the dripping amount of the sealing agent was adjusted so that the diameter of the sealing agent after bonding became about 3 mm. After the two bonded substrates were fixed with a jig, they were thermally hardened at 120 ° C. for 1 hour to prepare a sample for evaluation of sealing adhesion. Evaluation of the sealing adhesiveness was performed by the said measuring method. The evaluation result of the sealing adhesiveness was 91 N / cm ² , which was not a good result.

The liquid crystal alignment agent 1 was applied to a glass substrate with an IPS electrode and a glass substrate with a column spacer (2,000 rpm, 15 seconds) by a spinner method. After coating, the substrate was heated at 80 ° C for 3 minutes to evaporate the solvent. Then, using Multi-Light ML-501C / B manufactured by Oxtail Motor Co., Ltd., the polarized light was passed from a direction perpendicular to the substrate. The panel is irradiated with linear polarized light. The exposure energy at this time was measured using a UV cumulative light meter UIT-150 (light receiver: UVD-S365) manufactured by Oxtail Motor Co., Ltd. to measure the light amount to be 0.8 J / cm ² ± 0.1 J / at a wavelength of 365 nm. cm ² to adjust the exposure time. The sintering process was performed at 230 ° C for 20 minutes to form a film having a film thickness of approximately 100 nm. Then, the two substrates on which the liquid crystal alignment films are formed are bonded so that the liquid crystal alignment films are formed facing each other, and a space for injecting a liquid crystal composition is provided between the opposed liquid crystal alignment films. At this time, the polarization directions of the linearly polarized light irradiated to the respective liquid crystal alignment films are made parallel. A negative liquid crystal composition A was injected into these cells to produce a liquid crystal cell (liquid crystal display element) having a cell thickness of 7 μm. The contrast and AC afterimage characteristics of this unit were measured by the method described above. As a result, the contrast was 4,100 and the AC afterimage was 1.7%, showing good characteristics of the liquid crystal display element.

<Negative liquid crystal composition A> Physical properties: NI 75.7 ℃; Δε -4.1; Δn 0.101; η 14.5 mPa · s.

[Example 2 to Example 32] In addition to changing the varnish used, a liquid crystal alignment agent was prepared according to Example 1, and a sample and a liquid crystal cell for sealing adhesion evaluation were prepared, and evaluation of sealing adhesion, contrast and Evaluation of AC afterimage characteristics.

[Example 33] 4.0 g of the varnish 15 synthesized in Synthesis Example 15 and 6.0 g of the varnish synthesized in Synthesis Example 18 were weighed into a 50 mL eggplant-shaped flask equipped with a stirring blade and a nitrogen introduction tube, and added thereto 5.0 g of NMP and 5.0 g of BC. After stirring at room temperature for 2 hours, a liquid crystal alignment agent 33 having a polymer concentration of 3 wt% was obtained. In addition to changing the varnish used, a liquid crystal alignment agent was prepared according to Example 1, and a sample for sealing adhesion evaluation and a liquid crystal cell were prepared, and evaluation of sealing adhesion, contrast, and AC afterimage characteristics were performed.

[Example 34] 4.0 g of the varnish synthesized in Synthesis Example 16 and 6.0 g of the varnish synthesized in Synthesis Example 19 were weighed into a 50 mL eggplant-type flask equipped with a stirring blade and a nitrogen introduction tube, and added thereto. 5.0 g of NMP and 5.0 g of BC. After stirring at room temperature for 2 hours, a liquid crystal alignment agent 34 having a polymer concentration of 3 wt% was obtained. In addition to changing the varnish used, a liquid crystal alignment agent was prepared according to Example 1, and a sample for sealing adhesion evaluation and a liquid crystal cell were prepared, and evaluation of sealing adhesion, contrast, and AC afterimage characteristics were performed.

[Example 35] 5.0 g of the varnish 16 synthesized in Synthesis Example 16 and 5.0 g of the varnish 20 synthesized in Synthesis Example 20 were weighed into a 50 mL eggplant-type flask equipped with a stirring blade and a nitrogen introduction tube, and added thereto 5.0 g of NMP and 5.0 g of BC. After stirring at room temperature for 2 hours, a liquid crystal alignment agent 35 having a polymer concentration of 3 wt% was obtained. In addition to changing the varnish used, a liquid crystal alignment agent was prepared according to Example 1, and a sample for sealing adhesion evaluation and a liquid crystal cell were prepared, and evaluation of sealing adhesion, contrast, and AC afterimage characteristics were performed.

The varnishes used in Examples 1 to 35 and the measurement results are shown in Table 4.

Table 4

[Comparative Example 1 to Comparative Example 3] Except changing the varnish used, a liquid crystal alignment agent was prepared according to Example 1, and a sample and a liquid crystal cell for sealing adhesion evaluation were prepared, and evaluation of sealing adhesion, contrast, and Evaluation of AC afterimage characteristics. The varnish used and the measurement result are shown in Table 5.

table 5

In all the samples of Examples 1 to 35, the sealing adhesion, contrast, and AC afterimage characteristics were good. According to the effect of the hydroxyl group of the diamine represented by Formula (I), it is thought that sealing adhesiveness improves. In addition, by setting the weight-average molecular weight of the polymer A (varnish A) to 12,000 or less, as described above, the layer separation property is improved, and the sealing adhesion, contrast, and AC afterimage characteristics are improved.

On the other hand, in Comparative Example 1 and Comparative Example 2, the sealing adhesion was low, and a result with good contrast and AC afterimage characteristics could not be obtained. In Comparative Example 2, although the sealing adhesion was good, a result with good contrast and AC afterimage characteristics could not be obtained.

According to the present invention, it is possible to provide a liquid crystal alignment agent for photoalignment, which provides a liquid crystal alignment film having a high adhesion with an interface with a sealant and a liquid crystal display element with high display quality. In addition, the present invention can provide a liquid crystal alignment film formed using the liquid crystal alignment agent for light alignment, and a liquid crystal display element including the liquid crystal alignment film.

[Industrial Applicability] According to the liquid crystal alignment agent for optical alignment of the present invention, a liquid crystal display element with high display quality can be provided. The liquid crystal alignment agent for optical alignment of the present invention can be preferably applied to a lateral electric field type liquid crystal display element.

no

no

Claims (11)

A liquid crystal alignment agent for photo-alignment includes at least one polymer as a reaction product of a raw material monomer containing a tetracarboxylic dianhydride and a diamine; the liquid crystal alignment agent for photo-alignment is characterized in that: the polymerization The substance includes the following polymer (H); a raw material monomer for synthesizing the polymer (H) includes at least one kind of a compound having a photoreactive structure, and includes a compound represented by the following formula (I) At least one; and the weight average molecular weight of the polymer (H) is 12,000 or less; here, the polymer is selected from the group consisting of polyamic acid, polyimide, part of polyimide, and polyimide At least one of the group consisting of polyamidoamine-polyamidoamine copolymer and polyamidoamimine; In formula (I), R is a structure represented by (a), (b), or (c); in formulas (a) and (b), R ⁰ is hydrogen or methyl. The liquid crystal alignment agent for photo-alignment according to claim 1, comprising the polymer (H) and other polymers used in combination with the polymer (H) for synthesizing the other polymers The raw material monomer of the product does not include a compound having a photoreactive structure, and does not include a compound represented by the formula (I). The liquid crystal alignment agent for photo-alignment according to claim 1, wherein the compound represented by the formula (I) is a group selected from the group consisting of compounds represented by the following formulae (I-1) to (I-10) At least one of . The liquid crystal alignment agent for photoalignment according to any one of claims 1 to 3, wherein the photoreactive structure of the raw material monomer is a photoisomerization structure. The liquid crystal alignment agent for photoalignment according to claim 4, wherein the tetracarboxylic dianhydride or diamine having the photoisomerized structure is at least a compound represented by formula (II) to formula (VI) One kind In formulae (II) to (V), R ² and R ³ are a monovalent organic group having -NH ₂ or a monovalent organic group having -CO-O-CO-, and in formula (IV), R ⁴ is A divalent organic group. In Formula (VI), R ^{5 is} independently an aromatic ring having -NH ₂ or -CO-O-CO-. The liquid crystal alignment agent for photoalignment according to claim 5, wherein the tetracarboxylic dianhydride or diamine having the photoisomerized structure is selected from the group consisting of formula (II-1) and formula (II-2) , Formula (III-1), formula (III-2), formula (IV-1), formula (IV-2), formula (V-1) to formula (V-3), formula (VI-1), And at least one of the group of compounds represented by formula (VI-2); In the above formulas, a group in which the bonding position is not fixed on any carbon atom constituting the ring indicates that the bonding position on the ring is arbitrary; in formula (V-2), R ^{6 is} independently -CH ₃ , -OCH ₃ , -CF ₃ , or -COOCH ₃ , a is an integer of 0 to 2; In formula (V-3), ring A and ring B are each independently selected from monocyclic hydrocarbons and condensed polycyclic hydrocarbons. And at least one of heterocycles, R ¹¹ is a linear alkylene group having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N (CH ₃ ) CO-, or- CON (CH ₃ )-, R ¹² is a linear alkylene group having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N (CH ₃ ) CO-, or -CON In (CH ₃ )-, R ¹¹ and R ¹² , one or discontinuous two -CH ₂ -in the linear alkylene group may be substituted by -O-, and R ⁷ to R ¹⁰ are each independently -F,- CH ₃ , -OCH ₃ , -CF ₃ , or -OH, and b to e are each independently an integer of 0 to 4. The liquid crystal alignment agent for photo-alignment according to any one of claims 1 to 6, further comprising a compound selected from an alkenyl-substituted nadicarium imine compound and a compound having a radical polymerizable unsaturated double bond At least one selected from the group consisting of oxazine compounds, oxazoline compounds, and epoxy compounds. The liquid crystal alignment agent for photoalignment according to any one of claims 1 to 7, which is used for manufacturing a lateral electric field type liquid crystal display element. A liquid crystal alignment film, which is formed by the liquid crystal alignment agent for photo alignment according to any one of claims 1 to 8. A liquid crystal display element comprising the liquid crystal alignment film according to claim 9. A lateral electric field type liquid crystal display device, comprising the liquid crystal alignment film according to claim 9.