WO2015053237A1

WO2015053237A1 - Polyimide composition, and alignment film and optical element formed using polyimide composition

Info

Publication number: WO2015053237A1
Application number: PCT/JP2014/076734
Authority: WO
Inventors: 美香山口; 二郎杉山; 政昭西村; 充哉青葉; 輝恒大澤
Original assignee: 三菱化学株式会社
Priority date: 2013-10-07
Filing date: 2014-10-06
Publication date: 2015-04-16
Also published as: JPWO2015053237A1; JP6428634B2; CN105612441A; KR20160068764A

Abstract

　A polyimide composition used in an alignment film for an anisotropic pigment film, the polyimide composition characterized in that the polyimide composition includes a polyimide and a solvent, and the polyimide is represented by general formula (1). (In general formula (1), X represents a tetravalent aliphatic hydrocarbon having a carbon number of at least 5, R¹ represents a divalent organic group having an aromatic ring, n represents an integer of 1 or higher, and when n is 2 or higher, a plurality of R¹ and X present in a molecule of the structure represented by general formula (1) may each be the same or different.)

Description

Polyimide composition, alignment film formed using said polyimide composition, and optical element

The present invention relates to a polyimide composition containing a polyimide having a specific structure and used for an alignment film for an anisotropic dye film. The present invention also relates to an alignment film and an optical element formed using the polyimide composition.

In recent years, with the widespread use of liquid crystal displays, the use of liquid crystal displays in various applications has been promoted. Along with this, various issues have been proposed and studied. Among them, with respect to optical elements, particularly polarizing elements, there is an increasing demand for durability against humidity, heat and light. The conventional liquid crystal display uses a polarizing film obtained by dyeing and stretching a polyvinyl alcohol (PVA) film or the like with a solution containing a dye, and orienting the dye in the drawing process, and therefore has low durability against humidity. . Therefore, establishment of a technique for an anisotropic dye film (polarizing film) using a dye that improves wet resistance and heat resistance is expected.
As a method for obtaining an anisotropic dye film, a method for obtaining an anisotropic dye film by applying a dichroic dye to a polymer surface is disclosed (Patent Document 1).

Moreover, when obtaining by apply | coating an anisotropic pigment | dye film | membrane, the orientation film | membrane is provided on a coating substrate and the pigment | dye is made to align. For example, it is disclosed that an alignment film is obtained by applying a polyamic acid solution (polyimide precursor) to a substrate and heating (Patent Document 2).
As the alignment film, an alignment film for liquid crystal has been conventionally studied, and it is disclosed that a liquid crystal alignment film is obtained by applying a polyamic acid solution to a substrate and heating (Patent Document 3).
On the other hand, polyimide has been studied as an optical film application. For example, in order to obtain a film having excellent heat resistance, transmittance, mechanical properties, and heat resistance, it is disclosed that a polyamic acid solution is heated after coating (Patent Documents 4 and 6). In addition, it is disclosed that a film is obtained by applying a polyimide solution having excellent solubility in organic solvents, heat resistance, dimensional stability, and transparency (Patent Document 5).

In recent years, in order to respond to the development of weight reduction, impact resistance improvement, and flexibility of liquid crystal displays, studies have been made on using a plastic substrate. Since the plastic substrate used for these has low heat resistance, it is required to lower the temperature of the manufacturing process of the liquid crystal display.
In order to increase the brightness of a liquid crystal display, it has been studied to use a colorant for a color filter as a dye. In this case, due to the low heat resistance of the dye, it is required that the temperature of the process after producing the color filter be 180 ° C. or lower, which is lower than the conventionally used temperature (Patent Document 7).

JP 2009-217011 Japanese Unexamined Patent Publication No. 2010-72521 Japanese Unexamined Patent Publication No. 2000-305088 Japanese Laid-Open Patent Publication No. 8-104750 Japanese Unexamined Patent Publication No. 2012-146905 Japanese Unexamined Patent Publication No. 2007-161930 Japanese Unexamined Patent Publication No. 2011-253054

Patent Document 1 discloses that an anisotropic dye film is produced by applying a dichroic dye to a polymer surface, but no consideration is given to providing an alignment film.
Patent Documents 2 and 3 disclose that a polyimide film is obtained by applying a polyamic acid solution on a substrate and performing a heat treatment at a high temperature of 200 ° C. or higher. Therefore, an alignment film for an anisotropic dye film cannot be formed on a material having a heat resistance of 200 ° C. or less. For example, a high-intensity color filter using a dye that has been developed in recent years has a problem that the luminance is lowered when processed at a high temperature of 200 ° C. or higher.

On the other hand, when a polyamic acid solution is applied to a substrate or the like and heat-treated at 200 ° C. or lower, the imidization reaction does not proceed sufficiently, and the amic acid portion remains in the alignment film. The remaining amic acid portion tends to cause the following problems (1) to (6). Therefore, the alignment film using the polyamic acid as described above cannot be used as an alignment film for an anisotropic dye film.
(1) Even after the optical element is formed using the alignment film, the imidization reaction of the alignment film proceeds, and this water generated by water breaks the association of the anisotropic dye, resulting in deterioration of the anisotropic dye film.
(2) The remaining amic acid site is hydrolyzed and the molecular weight of the polyimide is lowered, whereby the physical properties of the alignment film are changed and the alignment characteristics are deteriorated.
(3) The remaining amic acid site is hydrolyzed to generate a highly reactive carboxylic acid end or amine end, thereby accelerating the deterioration and coloring of the dye and peripheral members in the anisotropic dye film.
(4) Solvent molecules trapped in the amic acid moiety having a high affinity with the solvent are difficult to remove even during the drying process, and are volatilized as outgas during the subsequent process and storage, thereby degrading the device and peripheral members.
(5) Upon application of the anisotropic dye film composition, the remaining amic acid site absorbs the solvent or the like in the anisotropic dye film composition, and the alignment film swells. Further, by releasing the absorbed water, the association of the anisotropic dye is broken and the anisotropic dye film is deteriorated.
(6) In order to reduce the remaining amic acid sites, when a ring-closing imidization reaction is performed after applying polyamic acid, water generated along with ring-closing causes surface unevenness and microbubbles in the alignment film. The alignment film in which these occur is poor in surface smoothness and inhibits the alignment characteristics and surface smoothness of the anisotropic dye film.

Further, Patent Document 3 discloses that polyimide is used for the alignment film for liquid crystal, but no investigation is made as an alignment film for an anisotropic dye film. The alignment film for liquid crystal aligns liquid crystal molecules of which one molecule is about several tens of thousands. On the other hand, an alignment film for an anisotropic dye film needs to align about several hundreds of columns in which anisotropic dyes are associated. Due to the difference in size of the alignment material, the characteristics required for each alignment film are different, and the alignment film for liquid crystal cannot be diverted to the alignment film for anisotropic dye film.
Patent Documents 4 to 6 are optical film applications, and it is difficult to divert them to alignment films for anisotropic dye films. Further, in Patent Documents 4 and 6, as in Patent Documents 2 and 3, in order to obtain a film, it is necessary to perform a heat treatment at a high temperature of 200 ° C. or higher after applying the polyamic acid solution. Further, according to the study by the present inventors, the polyimide used in Patent Document 5 has a high hydrophobicity, and there is a problem that the applicability to the anisotropic dye film composition is lowered.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a polyimide composition containing polyimide having excellent solubility in a solvent. Moreover, when a polyimide composition is excellent in applicability | paintability and forms an oriented film using a polyimide composition, it makes it a subject to provide the polyimide composition which can be processed at low temperature. Furthermore, it is an object of the present invention to provide a polyimide composition having high surface treatment resistance and high alignment characteristics of the obtained alignment film.

As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention have excellent solubility in a solvent of a specific structure. By using a polyimide composition containing the polyimide and the solvent, the polyimide composition can be applied. I found it excellent. By using a polyimide composition containing a highly soluble polyimide, it is not necessary to perform an imidization reaction at a high temperature after coating. That is, when forming the alignment film, it is only necessary to remove the solvent of the applied alignment film, and since it can be performed at a temperature lower than 200 ° C., the alignment film can be formed on a material such as a color filter. I found it.
Further, it has been found that the alignment film obtained from the polyimide composition is excellent in surface treatment resistance such as rubbing and has high alignment characteristics of the anisotropic dye film.
The present invention has been accomplished based on these findings.

That is, the gist of the present invention resides in the following [1] to [5].
[1]
A polyimide composition used for an alignment film for anisotropic dye film,
The polyimide composition includes a polyimide and a solvent,
The said polyimide is represented by General formula (1), The polyimide composition characterized by the above-mentioned.

(In the general formula (1), X represents a tetravalent aliphatic hydrocarbon group having 5 or more carbon atoms,
R ¹ represents a divalent organic group having an aromatic ring,
n represents an integer of 1 or more, and when n is 2 or more, a plurality of R ¹ and X present in one molecule of the structure represented by the general formula (1) may be the same or different. Good. )
[2]
The polyimide composition as described in [1] above, wherein the ratio of the number of elements forming an aromatic ring is 5% or more and 75% or less of the number of elements forming the main chain of the polyimide.
[3]
The polyimide composition according to the above [1] or [2], wherein the imidization ratio of the polyimide is 90% or more.
[4]
An alignment film for an anisotropic dye film, which is formed using the polyimide composition according to any one of [1] to [3].
[5]
An optical element having the anisotropic dye film alignment film according to [4] and an anisotropic dye film laminated on the anisotropic dye film alignment film.

The polyimide having a specific structure of the present invention is excellent in solubility in a solvent, and the polyimide composition containing the polyimide and the solvent is excellent in coatability. By using the polyimide composition of the present invention, it is not necessary to perform an imidization reaction at a high temperature after coating, and only the solvent removal of the coating film can be performed at a low temperature, and an alignment film is formed on a material such as a color filter. can do.
In addition, it is possible to obtain an alignment film that is excellent in surface treatment resistance against a process such as rubbing and that has high alignment characteristics of an anisotropic dye film.

The reason for the above effect is not clear, but is presumed as follows. Improve the solubility of the polyimide in the solvent by X of the polyimide represented by the general formula (1) contained in the polyimide composition of the present invention being a tetravalent aliphatic hydrocarbon group having 5 or more carbon atoms. Can do. Since the polyimide in the polyimide composition is difficult to deposit, the applicability of the polyimide composition is improved. In addition, since the polyimide composition of the present invention has high solubility in a solvent even when the imidization ratio of polyimide is high, it is not necessary to carry out an imidation reaction by heating after coating, and the solvent is used at a temperature of 200 ° C. or lower. It is possible to form an alignment film by removing.

Since R ^{1 in the} general formula (1) is a divalent organic group having an aromatic ring, the polyimide of the present invention has a rigid structure and linearity. Since the polyimide has linearity, the effect of surface treatment such as rubbing on the alignment film is more easily obtained. Due to the effect of the surface treatment such as rubbing, the linearity of the polyimide in the alignment film increases, and the alignment characteristics of the anisotropic dye film formed on the surface can be enhanced.
Since R ¹ is a divalent organic group having an aromatic ring, the R ¹ moiety exhibits an electron donating property (donor). On the other hand, since the imide ring structure portion of polyimide exhibits an electron accepting property (acceptor), the association property of the polyimide in the polyimide composition is obtained by the donor-acceptor interaction. Therefore, the alignment characteristic of the alignment film can be improved, and the alignment characteristic of the anisotropic dye film formed on the surface can be improved.
In addition, the polyimide of the present invention has a rigid structure and, as described above, the associative properties of the polyimide can be obtained, so that the surface treatment resistance is excellent. Therefore, it is possible to perform a strong surface treatment on the alignment film, and further improve the alignment characteristics of the polyimide. In the present invention, the electron donating property refers to a state where the electron density of the π electron cloud on the aromatic ring is high, and the electron accepting property refers to a state where the electron density is low.

Since the polyimide of the present invention is a combination of the above X and R ¹ , the association of the polyimide in the polyimide composition by the donor-acceptor interaction can be improved while maintaining the solubility in a solvent. Therefore, the alignment characteristic of the obtained alignment film is improved, and the alignment characteristic of the anisotropic dye film can be enhanced. In addition, since the alignment film of the present invention has an aromatic ring and is excellent in interaction with an anisotropic dye having an aromatic ring, the alignment characteristics of the anisotropic dye film tend to be further improved. In addition, unlike the liquid crystal molecules, the anisotropic dye has a relatively large association (column) structure of about several hundreds of pieces with which the anisotropic dye is associated. Therefore, it is considered that the anisotropic dye hardly aligns following the alignment film. Therefore, in order to align the anisotropic dye, an alignment film having high alignment characteristics is required. However, the polyimide having a specific structure according to the present invention has high alignment characteristics of the alignment film due to the above-described reasons. It is suitable for orienting the dye.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. However, the objects and methods exemplified below are examples (representative examples) of the embodiments of the present invention, and the present invention includes these contents unless departing from the gist thereof. It is not limited to.
Here, in the present specification, “mass%” and “wt%” are synonymous.

1. Polyimide composition The polyimide composition of this invention has the characteristics in containing the polyimide and solvent which are represented by General formula (1).

(In the general formula (1), X represents a tetravalent aliphatic hydrocarbon group having 5 or more carbon atoms,
R ¹ represents a divalent organic group having an aromatic ring,
n represents an integer of 1 or more, and when n is 2 or more, a plurality of R ¹ and X present in one molecule of the structure represented by the general formula (1) may be the same or different. Good. )

The polyimide composition of the present invention may contain a plurality of polyimides as long as it contains the polyimide represented by the general formula (1). The polyimide of the present invention does not need to be synthesized under the same reaction conditions, or only those having the same aromatic element ratio, imidization rate, and solubility. Mixtures prepared under different conditions and having different physical properties may be used. In the present invention, the aromatic ring element ratio and imidation rate described below are average values of the polyimide constituting the polyimide composition.
Moreover, the polyimide composition of this invention may contain components other than a polyimide, if it is a range which does not impair the effect of this invention.

1.1 Solvent The solvent used in the polyimide composition of the present invention is not particularly limited. For example, hydrocarbon solvents such as hexane, cyclohexane, and heptane; aromatics such as benzene, toluene, xylene, mesitylene, phenol, cresol, and anisole. Solvents: Halogenated hydrocarbon solvents such as carbon tetrachloride, methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene and fluorobenzene; Ether systems such as diethyl ether, tetrahydrofuran, 1,4-dioxane and methoxybenzene Solvent: Ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, etc .; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, die Glycol solvents such as lenglycol dimethyl ether and propylene glycol monomethyl ether acetate; amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; aprotic polarities such as dimethyl sulfoxide Solvents; heterocyclic solvents such as pyridine, picoline, lutidine, quinoline and isoquinoline; lactone solvents such as γ-butyrolactone, γ-valerolactone and δ-valerolactone; These solvents may be used alone or in combination of two or more in any ratio and combination.
Among these, it is preferable to use a hydrocarbon solvent, an aromatic solvent, a glycol solvent, and an amide solvent. In particular, toluene, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and anisole are preferably used. Use of these solvents tends to improve the solubility of polyimide and facilitate the removal of the solvent when forming the alignment film.

1.2 Polyimide The polyimide according to the present invention is not particularly limited as long as it includes a repeating unit containing at least an imide bond and has a skeleton having a specific structure represented by the general formula (1).

(N)
n is an integer of 1 or more, and there is no particular upper limit as long as the effect of the present invention is not impaired, but n is set so that the mass average molecular weight of the polyimide represented by the general formula (1) is in the range described later. It is preferable to define. These ranges are preferable because the solubility of the polyimide in the solvent, the viscosity of the polyimide composition, and the like tend to be in a range in which an alignment film can be easily formed.
When n is 2 or more, R ¹ and X present in a plurality in one molecule of the structure represented by the general formula (I) may be the same or different.

(X)
X in the general formula (1) represents a tetravalent aliphatic hydrocarbon group having 5 or more carbon atoms. The aliphatic hydrocarbon group is cyclic or chain-like and may be a combination of these.
X has 5 or more carbon atoms, preferably 6 or more. Further, it is preferably 20 or less, more preferably 16 or less, and particularly preferably 14 or less. When the carbon number is within this range, the solubility of the polyimide in the solvent is improved, the polyimide composition is excellent in applicability, and heating after application tends to be performed at a low temperature.

Among the aliphatic hydrocarbon groups, the cyclic aliphatic hydrocarbon group or a group in which cyclic and chain aliphatic hydrocarbon groups are combined improves the solubility of the polyimide in the solvent and the applicability of the polyimide composition. In addition, it is preferable because heating after coating tends to be performed at a low temperature.

Examples of the chain aliphatic hydrocarbon group include an alkylene group which may have a substituent. The chain aliphatic hydrocarbon group may be a straight chain or may have a branch. Examples of the substituent that the alkylene group may have include an alkoxyl group having 1 to 4 carbon atoms and a trifluoromethyl group.

The cyclic aliphatic hydrocarbon group is a monocyclic ring, a condensed polycyclic ring, or a ring linked to each other directly or by a bridging member. Specific examples include groups derived from alicyclic tetracarboxylic dianhydrides described below.
Among the cyclic aliphatic hydrocarbon groups, a single ring or a group in which single rings are connected to each other directly or by a crosslinking member is preferable because the solubility of polyimide in a solvent tends to be improved.

Specific examples of the monocyclic and condensed polycyclic aliphatic hydrocarbon groups share a single ring such as cyclopentane, cyclopentene, cyclohexane, cyclohexene, cycloheptane, and the two carbon atoms of the monocycle. A condensed polycycle is mentioned.
Among these, the structure of the following formula (2), formula (3) or formula (4) is preferable, and the structure of formula (2) or formula (3) is particularly preferable. With these structures, the solubility of polyimide in a solvent is improved, the applicability of the polyimide composition is excellent, and heating after application tends to be performed at a low temperature.

The cyclic aliphatic hydrocarbon group in which monocyclic or condensed polycycles are directly or mutually linked by a bridging member has a structure represented by the following general formula (5), and the solubility of polyimide in a solvent is It is preferable because it is improved, the applicability of the polyimide composition is excellent, and heating after application tends to be performed at a low temperature.

In General Formula (5), X ¹ and X ² each independently represent a divalent cyclic aliphatic hydrocarbon group having 5 or more carbon atoms, and R ² is a carbon that may have a direct bond or a substituent. This represents an alkylene group of 1 to 6 or a group represented by the following.

^{(X 1} and ^X 2)
The divalent cyclic aliphatic hydrocarbon group for X ¹ and X ² is not particularly limited as long as it has 5 or more carbon atoms, but preferably has 10 or less carbon atoms, more preferably 8 or less. Furthermore, it is C5 and C6, the solubility to the solvent of a polyimide improves, it exists in the tendency which is excellent in the applicability | paintability of a polyimide composition, and can perform the heating after application | coating at low temperature.
X ¹ and X ² may have a substituent, and an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, a carboxy group, a sulfo group, an amino group Group, cyano group, nitro group, halogen atom and the like.

(R ² )
R ² is a direct bond, an alkylene group having 1 to 6 carbon atoms which may have a substituent, or a group represented by the following.

Among these, a direct bond is preferable because the solubility of polyimide in a solvent is improved, the applicability of the polyimide composition is excellent, and heating after application tends to be performed at a low temperature.
Examples of the substituent that the alkylene group of R ² may have include an alkoxy group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, a carboxy group, a sulfo group, a cyano group, a nitro group, and a halogen atom. And an alkylthio group having 1 to 5 carbon atoms, a trifluoromethyl group, and the like.

Among the general formula (5), the following general formula (6) is preferable, and the following general formula (7) further improves the solubility of the polyimide in the solvent and improves the applicability of the polyimide composition. It is preferable because it is excellent and tends to be able to perform heating after coating at a low temperature.

R ^{3 in the} general formula (6) has the same definition as R ^{2 in the} general formula (5), and a preferred range is also the same.

(R ¹ )
R ¹ represents any divalent organic group having an aromatic ring. R ¹ is not particularly limited as long as it is a divalent group having an aromatic ring, and the number of aromatic rings is not particularly limited. Moreover, groups other than an aromatic ring may be included.
The aromatic ring of the organic group may be a single ring, a condensed polycycle, and those in which these are connected to each other directly or by a bridging member. Moreover, the aromatic ring may be connected with a group other than the aromatic ring.

Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a biphenylene ring, and a fluorene ring.
These aromatic rings may have a substituent. Examples of the substituent which may be included include an alkyl group having 1 to 5 carbon atoms, a sulfo group, a cyano group, a trifluoromethyl group, and a halogen atom.
Examples of the group other than the aromatic ring include an alkylene group having 1 to 4 carbon atoms, an alkenylene group having 1 to 4 carbon atoms, and a group represented by the following.

Among the groups other than the aromatic ring, the alkylene group having 1 to 4 carbon atoms and the alkenylene group having 1 to 4 carbon atoms may have a substituent. Examples of the substituent which may be included include an alkoxy group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, a carboxy group, a sulfo group, a cyano group, a nitro group, a halogen atom, and 1 to 5 carbon atoms. And the like.

The connection position at which the aromatic ring is connected by a direct bond and a group other than the aromatic ring is not particularly limited, but the connection is preferably performed at a position that does not hinder the rigidity, association, and orientation characteristics of the polyimide molecule.
Specific examples of R ¹ include a divalent group obtained by removing an amino group from a diamine compound, which is a raw material for polyimide represented by the general formula (1) described later.

Among these, the aromatic ring of R ¹ is preferably a single ring from the viewpoint of solubility of polyimide in a solvent. Further, R ¹ has 1 or more aromatic rings, and preferably 2 or more. The number of aromatic rings is preferably 6 or less, and more preferably 4 or less. When the number of aromatic rings is within the above range, solubility of polyimide in a solvent can be obtained, and further, rigidity and association of polyimide can be improved, and alignment characteristics and surface treatment resistance of the resulting alignment film can be improved. Tend to.

Further, R ¹ is particularly preferably a structure represented by the following formula (8), (9), (10) or (11). With these structures, the solubility of polyimide in a solvent can be obtained, the rigidity and association of polyimide can be improved, and the orientation characteristics and surface treatment resistance of the resulting alignment film tend to be improved. .

R ¹⁰ in formula (9), R ¹¹ to R ¹² in formula (10), and R ¹³ to R ¹⁵ in formula (11) are each independently a linking group other than a divalent aromatic ring, specifically Represents the above-mentioned groups other than the aromatic ring of R ¹ .
Further, each aromatic ring of the formulas (8) to (11) may have an alkyl group having 1 to 5 carbon atoms, a sulfo group, a cyano group, a trifluoromethyl group, a halogen atom or the like as a substituent.

R ¹⁰ to R ¹⁵ are each an alkylene group having 1 to 4 carbon atoms or a group represented by the following, whereby the rigidity and associative properties of the polyimide are improved, and the orientation characteristics and surface resistance of the resulting orientation film are improved. Is preferable because of a tendency to improve.

Further, at least one of R ¹⁰ , R ¹¹ and R ¹² , or at least one of R ¹³ to R ¹⁵ is —O—, which increases the electron donating property of R ¹ , This is particularly preferable because the associating property of the polyimide by the action is improved and the orientation characteristics of the obtained orientation film tend to be improved.

(Combination of X and R ¹ )
The combination of X and R ¹ described above is not particularly limited, but a combination in which X is a cyclic aliphatic hydrocarbon group and R ¹ has a structure having a plurality of monocyclic aromatic rings is preferable. In particular, it is preferable that X includes at least one structure represented by formulas (2) to (7) and R ¹ includes at least one structure represented by formulas (8) to (9). By combining these, the association property of the polyimide in the polyimide composition due to the donor-acceptor interaction is improved, and the alignment characteristics of the resulting alignment film tend to be improved.

(Other structures)
The polyimide of the present invention is not particularly limited as long as it contains the polyimide represented by the general formula (1), and a combination of a unit derived from tetracarboxylic dianhydride and / or a unit derived from a diamine compound is used in combination. It may be polymerized. Moreover, polyimides other than the polyimide represented by General formula (1) may be included in the polyimide composition.
The unit derived from the tetracarboxylic dianhydride to be copolymerized may contain other than aliphatic hydrocarbon groups having 5 or more carbon atoms as long as the effects of the present invention are not impaired. Specific examples include an aromatic ring such as a benzene ring and a naphthalene ring, a group in which an aromatic ring is directly bonded, a group in which a plurality of aromatic rings are connected with a linking group other than an aromatic ring, and the like. The aromatic ring may have a substituent, and examples thereof include an alkyl group having 1 to 5 carbon atoms, a sulfo group, a cyano group, a trifluoromethyl group, and a halogen atom.
Specific examples of the unit derived from the tetracarboxylic dianhydride to be copolymerized include groups derived from a tetracarboxylic dianhydride having an aromatic ring, which will be described later, as a polyimide raw material. Among these, examples of the group derived from tetracarboxylic dianhydride having an aromatic ring include structures represented by the following formulas (12) to (14). The use of these is preferable because the rigidity and association of the polyimide are improved while maintaining the solubility of the polyimide in the solvent, and the alignment characteristics and surface treatment resistance of the resulting alignment film tend to be improved.
These aromatic rings may have a substituent. Examples of the substituent which may be included include an alkyl group having 1 to 5 carbon atoms, a sulfo group, a cyano group, a trifluoromethyl group, and a halogen atom.

R ¹⁵ represents an alkylene group having 1 to 4 carbon atoms, an alkenylene group having 1 to 4 carbon atoms, or a group represented by the following. The connecting position of R ¹⁵ is not particularly limited and it is preferably connected at a position that does not interfere with the rigidity, associative and alignment properties of the polyimide molecule.

In the present invention, among the units derived from the tetracarboxylic dianhydride contained in the polyimide, other than the units derived from the tetracarboxylic dianhydride used in the general formula (1) (other tetracarboxylic dianhydrides to be copolymerized) The proportion of units derived from anhydride is preferably 0.1 mol% or more, more preferably 1 mol% or more, preferably 99 mol% or less, more preferably 90 mol% or less. By being in these ranges, while maintaining the solubility of the polyimide in the solvent, the rigidity and association properties of the polyimide are improved, and the orientation characteristics and surface treatment resistance of the resulting alignment film tend to be improved. preferable.

The unit derived from the diamine compound to be copolymerized may not contain an aromatic ring as long as the effects of the present invention are not impaired. Examples thereof include a cyclic or chain aliphatic hydrocarbon group, a group connecting aliphatic hydrocarbon groups, and the like. In addition, these groups may have a substituent, and examples thereof include an alkyl group having 1 to 5 carbon atoms, a sulfo group, a cyano group, a trifluoromethyl group, and a halogen atom.
Specific examples include a divalent group obtained by removing an amino group from an aliphatic diamine compound having no aromatic ring, which will be described later, as a raw material for polyimide.

Of the units derived from the diamine compound contained in the polyimide of the present invention, the proportion of units other than the units derived from the diamine compound used in the general formula (1) (units derived from other diamine compounds to be copolymerized) is preferably It is 0.1 mol% or more, preferably 50 mol% or less, more preferably 40 mol% or less. By being in these ranges, while maintaining the solubility of the polyimide in the solvent, the rigidity and association properties of the polyimide are improved, and the orientation characteristics and surface treatment resistance of the resulting alignment film tend to be improved. preferable.

(Ratio of the number of elements forming the aromatic ring of polyimide)
Of the number of elements forming the main chain of polyimide, the ratio of the number of elements forming an aromatic ring (hereinafter sometimes referred to as aromatic ring element ratio) is preferably 75% or less, more preferably 65% or less, It is preferably 60% or less, particularly preferably 55% or less, and most preferably 50% or less. Further, it is preferably 5% or more, more preferably 7% or more, and further preferably 10% or more. When the aromatic ring element ratio is in the above range, the polyimide is easily dissolved in the solvent, and when the polyimide composition is heated, precipitation or gelation tends not to occur. Here, the number of elements that form the main chain does not include the number of elements that form a hydrogen atom or a substituent that becomes a side chain.
The ratio of the aromatic ring element can be adjusted by adjusting the ratio of those having an aromatic ring with respect to the tetracarboxylic dianhydride and diamine compound (hereinafter sometimes referred to as “raw material monomer”) used as a raw material for polyimide synthesis. It can be a range. Moreover, the aromatic ring element ratio of the obtained polyimide and the alignment film containing the polyimide can be obtained by analyzing the composition of the raw material monomer obtained by solid NMR, IR, or the like.
It can also be determined by analyzing the composition of the raw material monomer determined by gas chromatography (GC), ¹ H-NMR, ¹³ C-NMR, two-dimensional NMR, mass spectrometry, etc. after dissolution with alkali.

The method of setting the aromatic ring element ratio of the polyimide within the above range includes tetracarboxylic dianhydride having an aromatic ring, tetracarboxylic dianhydride having no aromatic ring, diamine compound having an aromatic ring, and diamine having no aromatic ring. The compound can be obtained by using the aromatic ring element in a ratio that falls within the above range.

(Imidation rate of polyimide)
The imidation ratio of the polyimide is preferably 90% or more, more preferably 95% or more, and particularly preferably 98% or more. Moreover, there is no upper limit and the higher one is preferable.
When the imidation ratio is in a specific range, the remaining amount of amic acid when the alignment film is formed can be suppressed, and a change with time such as hydrolysis tends to hardly occur. In addition, when the imidization ratio is in a specific range, the necessity of performing an imidization reaction (heating) when forming the alignment film is reduced, and the alignment film tends to be obtained by heating at a low temperature. The imidation rate of this invention can be adjusted with the conditions of imidation in the manufacturing method mentioned later.

In the present invention, the imidation ratio indicates the ratio of imide bonds in the main chain of polyimide. The imidization rate can be determined by a conventionally known method such as NMR, IR, and titration. The imidation rate in the present invention is a value determined by IR.

An example of obtaining the imidization rate by IR will be described below. A signal that does not change before and after imidation, for example, an aromatic ring C = C stretching vibration derived from the backbone of the main chain, is used as a reference, and can be obtained from the intensity ratio or area ratio of the imide CN stretching vibration to the reference signal. it can.
Absorption strength of C = C stretching vibration of sample at 100% imidization (A), Absorption strength of CN stretching vibration (B), Absorption strength of C = C stretching vibration of sample subjected only to solvent drying ( A ′), the absorption strength (B ′) of CN stretching vibration is measured, and the imidation ratio of each polyimide composition can be calculated from the following formula (C).
Imidation ratio = (B ′ / A ′) / (B / A) * 100 (C)

∙ Preparation of 100% imidized sample is made by heating the sample to be measured at high temperature. The heating temperature is usually 200 ° C. or higher, preferably 250 ° C. or higher, more preferably 300 ° C. or higher. Although the drying temperature of a solvent can be determined according to the boiling point of the solvent used, it is usually 20 ° C. or higher, preferably 40 ° C. or higher, usually 200 ° C. or lower, and more preferably lower than the imidization reaction temperature. When the drying temperature is not too low, the solvent is sufficiently dried and unnecessary signals tend not to be observed during IR measurement. Further, since the drying temperature is not too high, the imidization rate does not change during drying, and an accurate imidization rate can be obtained.

(Polyimide solubility)
In the present invention, “soluble in a solvent” means complete dissolution when polyimide is dissolved in a solvent constituting the composition at room temperature (25 ° C.). The concentration for complete dissolution is usually 0.5% by mass or more, preferably 1% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more.
In the present invention, a polyimide soluble in a solvent can be obtained by setting the ratio of the aromatic ring element in the main chain and the imidization ratio within the above ranges.
The concentration of the composition can be confirmed by using a conventionally known method as appropriate. For example, the solvent of the composition is dried using a method such as drying under reduced pressure, and the mass ratio before and after drying. Can be obtained from
When the concentration of the composition is low, the composition can be concentrated by using a method such as distilling off the solvent under reduced pressure to determine solubility. When the concentration of the composition is high, the measurement concentration can be 1% by mass by diluting with the solvent of the composition. When the solvent of the composition is unknown, for example, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone; aprotic solvents such as dimethyl sulfoxide; ethylene Glycol solvents such as glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and propylene glycol monomethyl ether acetate; aromatic solvents such as benzene, toluene, xylene, mesitylene, phenol, cresol, and anisole; hexane , Hydrocarbon solvents such as cyclohexane and heptane;

(Ratio of the number of elements forming the aliphatic structure of polyimide)
Of the number of elements forming the main chain of polyimide, the ratio of the number of elements forming the aliphatic structure (hereinafter sometimes referred to as aliphatic element ratio) is 5 out of the number of elements forming the main chain of polyimide. % Or more, preferably 7% or more, particularly preferably 10% or more. Moreover, 60% or less is preferable, 50% or less is more preferable, 40% or less is further more preferable, and it is especially preferable to have 35% or less. By having an aliphatic structure in the main chain in an appropriate range, a polyimide composition containing a highly soluble polyimide tends to be obtained stably. Here, the number of elements that form the main chain does not include the number of elements that form a hydrogen atom or a substituent that becomes a side chain. In order to have an aliphatic structure as a structure that forms the main chain of polyimide, a tetracarboxylic dianhydride and a diamine compound having an aliphatic structure may be used in a ratio within an appropriate range. Here, the aliphatic structure includes both alicyclic and chain structures.

(Molecular weight of polyimide)
Although the weight average molecular weight (Mw) of a polyimide is not specifically limited, It is 1.0 * 10 < ³ > or more normally in polystyrene conversion, Preferably it is 5.0 * 10 < ³ > or more, More preferably, it is 1.0 * 10 < ⁴ > or more, Usually It is 1.0 × 10 ⁶ or less, preferably 8.0 × 10 ⁵ or less, more preferably 5.0 × 10 ⁵ or less. These ranges are preferable because the solubility of the polyimide in the solvent, the viscosity of the polyimide composition, and the like tend to be in a range in which an alignment film can be easily formed. The polystyrene-reduced weight average molecular weight can be determined by gel permeation chromatography (GPC).

The number average molecular weight (Mn) of the polyimide is not particularly limited, but is usually 5.0 × 10 ² or more, preferably 2.5 × 10 ³ or more, more preferably 5.0 × 10 ³ or more in terms of polystyrene, It is 5.0 × 10 ⁴ or less, preferably 4.0 × 10 ⁴ or less, more preferably 2.5 × 10 ⁴ or less. This range is preferable in terms of solubility, solution viscosity, melt viscosity, and the like that are easy to handle in normal production equipment. The number average molecular weight of polyimide can be measured by the same method as the above weight average molecular weight.

The molecular weight distribution of polyimide (PDI, (weight average molecular weight / number average molecular weight (Mw / Mn))) is usually 1 or more, preferably 1.1 or more, more preferably 1.2 or more, and usually 10 or less, preferably Is 9 or less, more preferably 8 or less. The molecular weight distribution is preferably in this range in that a highly uniform composition can be obtained. In addition, the molecular weight distribution of polyimide can be calculated | required from the value of the said weight average molecular weight and number average molecular weight.

1.3 Raw Material of Polyimide The polyimide according to the present invention is obtained by reacting a tetracarboxylic dianhydride and a diamine compound in an organic solvent.

(Tetracarboxylic dianhydride)
Examples of the tetracarboxylic dianhydride that is a raw material of the polyimide represented by the general formula (1) of the present invention include aliphatic tetracarboxylic dianhydrides having no aromatic ring. Examples of the aliphatic tetracarboxylic dianhydride include alicyclic tetracarboxylic dianhydrides and chain aliphatic tetracarboxylic dianhydrides.

Specific examples of the alicyclic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biscyclopentanetetracarboxylic dianhydride, 3,3 ′, 4,4′-biscyclohexanetetra Carboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, tricyclo [6.4.0.02,7 Dodecane-1,8: 2,7-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,1 '-Biscyclohexane-3,3', 4,4'-tetracarboxylic dianhydride, 1,1'-oxybiscyclohexane-3,3 ', 4,4'-tetracarboxylic dianhydride, 1, 1'-sulfonylbiscyclohexane-3,3 , 4,4′-tetracarboxylic dianhydride, 1,1′-biscyclohexyl ketone-3,3 ′, 4,4′-tetracarboxylic dianhydride, 1,1′-biscyclohexylmethyl-3, Examples thereof include 3 ′, 4,4′-tetracarboxylic dianhydride, 1,1 ′-(1-methylethylidene) biscyclohexyl-3,3 ′, 4,4′-tetracarboxylic dianhydride, and the like.

Of these, alicyclic tetracarboxylic dianhydrides are preferred. Among the alicyclic tetracarboxylic dianhydrides, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 3,3 ′, 4,4′-biscyclohexanetetracarboxylic dianhydride, 1, 2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,1′-bicyclohexane −3,3 ′, 4,4′-tetracarboxylic dianhydride improves the solubility of the polyimide in the solvent, improves the applicability of the polyimide composition, and allows heating after application at a low temperature. This is particularly preferable because it tends to be possible.
These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations.

(Diamine compound)
Examples of the diamine compound that is a raw material of the polyimide represented by the general formula (1) of the present invention include diamine compounds containing an aromatic ring. Examples of the diamine compound having an aromatic ring include a diamine compound having one aromatic ring contained in the molecule, a diamine compound having two or more independent aromatic rings, and a diamine compound having a condensed aromatic ring.

Specifically, a diamine compound having one aromatic ring contained in the molecule such as 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, etc .; 4,4 ′-(biphenyl- 2,5-diylbisoxy) bisaniline, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) Benzene, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, 1, 3-bis (4-aminophenoxy) neopentane, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-dia No-2,2′-dimethylbiphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-diamino-3,3′-dihydroxybiphenyl, bis (4-amino-3-carboxyphenyl) Methane, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, N- (4-aminophenoxy) -4-aminobenzamine, 2,2′-bis (trifluoromethyl) -4,4 '-Diaminobiphenyl, bis (3-aminophenyl) sulfone, norbornanediamine, 4,4'-diamino-2- (trifluoromethyl) diphenyl ether, 5-trifluoromethyl-1,3-benzenediamine, 2,2- Bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 4,4′-diamino-2,2 -Bis (trifluoromethyl) biphenyl, 2,2-bis [4- {4-amino-2- (trifluoromethyl) phenoxy} phenyl] hexafluoropropane, 2-trifluoromethyl-p-phenylenediamine, 2, Diamine compounds having two or more independent aromatic rings such as 2-bis (3-amino-4-methylphenyl) hexafluoropropane; 4,4 ′-(9-fluorenylidene) dianiline, 2,7-diaminofluorene, And diamine compounds having a condensed aromatic ring such as 1,5-diaminonaphthalene and 3,7-diamino-2,8-dimethyldibenzothiophene 5,5-dioxide.

Of the diamine compounds having an aromatic ring, it is preferable to use a compound having two or more independent aromatic rings. Among these, in particular, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diamino-2,2 '-Dimethylbiphenyl and bis (4- (4-aminophenoxy) phenyl) sulfone are particularly preferable because they can maintain a solubility and obtain a polyimide having excellent dimensional stability.
These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations.

In addition to the tetracarboxylic dianhydride and the diamine compound, a tetracarboxylic dianhydride having an aromatic ring and / or an aliphatic diamine compound having no aromatic ring are used within a range not impairing the effects of the present invention. Polymerization may be performed.

(Tetracarboxylic dianhydride having an aromatic ring)
The tetracarboxylic dianhydride having an aromatic ring includes a tetracarboxylic dianhydride having one aromatic ring in the molecule, a tetracarboxylic dianhydride having two or more independent aromatic rings, and condensation. Examples include tetracarboxylic dianhydrides having an aromatic ring.

Specifically, tetracarboxylic dianhydride having one aromatic ring contained in the molecule such as pyromellitic dianhydride and 1,2,3,4-benzenetetracarboxylic dianhydride; 1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane Anhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, 3, 3 ', , 4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride, 4,4- (p-phenylenediene) Oxy) diphthalic dianhydride, 4,4- (m-phenylenedioxy) diphthalic dianhydride, 2,2 ′, 6,6′-biphenyltetracarboxylic dianhydride, 2,2-bis (3 , 4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3 3,3-hexafluoropropane dianhydride, 2,2′-bis (trifluoromethyl) -4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride, 4,4 ′-(hexafluorotri Methylene) -diphthalic dianhydride 1,4 '-(octafluorotetramethylene) -diphthalic dianhydride, 4,4'-oxydiphthalic anhydride, etc., tetracarboxylic dianhydrides having two or more independent aromatic rings; , 5,6-Naphthalenedicarboxylic dianhydride, 1,4,5,8-naphthalenedicarboxylic dianhydride, 2,3,6,7-naphthalenedicarboxylic dianhydride, 3,4,9,10- Tetracarboxylic acid dianhydrides, 2,3,6,7-anthracene tetracarboxylic dianhydrides, 1,2,7,8-phenanthrenetetracarboxylic dianhydrides and the like tetracarboxylic acid dihydrates having a condensed aromatic ring Anhydrides; and the like.

Among these, it is preferable to use tetracarboxylic dianhydride having one aromatic ring contained in the molecule and tetracarboxylic dianhydride having two or more independent aromatic rings. Among these, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 3,3 ′, 4,4′- While biphenyltetracarboxylic dianhydride maintains the solubility of the polyimide in the solvent, the rigidity and associability of the polyimide are improved, and the orientation characteristics and surface treatment resistance of the resulting alignment film tend to be improved. Therefore, it is preferable.

(Aliphatic diamine compound having no aromatic ring)
Examples of the aliphatic diamine compound include alicyclic diamine compounds and chain aliphatic diamine compounds.

Specifically, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 4,4′- Alicyclic diamine compounds such as methylenebis (2-methylcyclohexylamine); (1,2-ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-hexamethylene Diamine, 1,5-diaminopentane, 1,10-diaminodecane, 1,2-diamino-2-methylpropane, 2,3-diamino-2,3-butanediamine, 2-methyl-1,5-diaminopentane ) And the like; and the like.

Among these, alicyclic diamine compounds are preferred, and among them, 1,4-diaminocyclohexane and 1,3-bis (aminomethyl) maintain the solubility of the polyimide in the solvent while maintaining the rigidity of the polyimide. This is preferable because the associative property is improved and the orientation properties and surface treatment resistance of the resulting alignment film tend to be improved.

1.4 Polyimide production method Although there is no particular limitation on the polyimide production method according to the present invention, for example, a method of producing a polyamic acid as a precursor to obtain a polyimide (two-stage method), tetracarboxylic dianhydride A method (one-step method) for producing polyimide directly from a product and a diamine compound is used.

(Two-stage method)
(Synthesis of polyamic acid)
The reaction for obtaining a polyamic acid from tetracarboxylic dianhydride and a diamine compound can be performed under conventionally known conditions. There are no particular limitations on the order of addition or addition method of the tetracarboxylic dianhydride and the diamine compound. For example, a polyamic acid composition can be obtained by sequentially adding tetracarboxylic dianhydride and a diamine compound to a solvent and stirring at an appropriate temperature.

The amount of the diamine compound is usually 0.7 mol or more, preferably 0.8 mol or more, and usually 1.3 mol or less, preferably 1.2 mol or less, relative to tetracarboxylic dianhydride. By making a diamine compound into such a range, it exists in the tendency for the yield of the polyamic acid obtained to improve.

The concentration of the tetracarboxylic dianhydride and the diamine compound in the solvent can be appropriately set according to the reaction conditions and the viscosity of the polyamic acid. For example, the total mass of the tetracarboxylic dianhydride and the diamine compound is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, based on the total liquid amount. Preferably it is 30 mass% or less. By setting the reaction substrate within this range, a polyamic acid can be obtained at a low cost and in a high yield.

The reaction temperature is not particularly limited as long as the reaction proceeds, but is usually 0 ° C or higher, preferably 20 ° C or higher, and usually 120 ° C or lower, preferably 100 ° C or lower. The reaction time is usually 1 hour or longer, preferably 2 hours or longer, usually 100 hours or shorter, preferably 24 hours or shorter. By carrying out the reaction under such conditions, a polyamic acid can be obtained at a low cost and in a high yield.
The pressure during the reaction may be normal pressure, increased pressure, or reduced pressure. The atmosphere may be air or an inert atmosphere.

The solvent used in this reaction is not particularly limited. For example, hydrocarbon solvents such as hexane, cyclohexane and heptane; aromatic solvents such as benzene, toluene, xylene, mesitylene, phenol, cresol and anisole; carbon tetrachloride, Halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, fluorobenzene; ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene; acetone, methyl ethyl ketone, cyclohexanone Ketone solvents such as methyl isobutyl ketone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ester Glycol solvents such as ether and propylene glycol monomethyl ether acetate; amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; aprotic polar solvents such as dimethyl sulfoxide; And heterocyclic solvents such as pyridine, picoline, lutidine, quinoline and isoquinoline; lactone solvents such as γ-butyrolactone, γ-valerolactone and δ-valerolactone. These solvents may be used alone or in combination of two or more in any ratio and combination.

The polyamic acid solution thus obtained may be used as it is, or may be added to a poor solvent to be precipitated as a solid and then re-dissolved in another solvent to obtain a polyimide composition. .

The poor solvent at this time is not particularly limited and may be appropriately selected depending on the type of polyimide resin. Ether solvents such as diethyl ether or diisopropyl ether; Ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone and methyl isobutyl ketone; Methanol , Alcohol solvents such as ethanol and isopropyl alcohol; and the like. Of these, alcohol solvents such as isopropyl alcohol are preferable in that precipitates can be obtained efficiently, the boiling point is low, and drying is easy.

The solvent for dissolving the polyamic acid is not particularly limited. For example, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; aprotic solvents such as dimethyl sulfoxide; Aromatic solvents such as benzene, toluene, xylene, mesitylene, phenol, cresol, anisole; glycol solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate; Can be mentioned. Of these, amide solvents, aromatic solvents and glycol solvents are preferred. In particular, N, N-dimethylformamide, N, N-dimethylacetamide or N-methyl-2-pyrrolidone, anisole, ethylene glycol dimethyl ether and ethylene glycol monomethyl ether are preferred. These can be used alone, and can also be used as a mixture of two or more.

(Production of polyimide composition from polyamic acid)
A polyimide composition can be obtained by dehydrating and cyclizing the above polyamic acid in the presence of a solvent. Although imidation can be performed using any conventionally known method, examples thereof include thermal imidization by thermal cyclization and chemical imidization by chemical cyclization. These imidization reactions may be used alone or in combination.

(Heat imidization)
The polyimide which is a specific imidation ratio of the present invention is a heating temperature, a heating time, a concentration of polyamic acid in a solvent, and, if an imidization accelerator is used, a kind, an addition amount, and an addition of an imidization accelerator It can be obtained by adjusting the timing of charging.
Examples of the solvent for imidizing the polyamic acid include the same solvents as those used in the reaction for obtaining the polyamic acid. The same or different solvents may be used for the polyamic acid production and the polyimide composition production.

In this case, water generated by the imidization reaction may be discharged out of the system in order to inhibit the ring closure reaction. The concentration of the polyamic acid during the imidation reaction is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less. By carrying out in this range, a polyimide having a controlled imidization rate can be obtained. In addition, polyimide can be produced with a solution viscosity that is high in production efficiency and easy to produce.

The imidization reaction temperature is not particularly limited as long as it does not depart from the gist of the present invention. It is usually 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 220 ° C. or lower, particularly preferably 200 ° C. or lower. By performing within this range, it is possible to obtain a polyimide in which the imidization reaction proceeds efficiently and the imidization rate is controlled. Moreover, since side reactions other than imidation reaction are suppressed, it is preferable.
The pressure during the reaction may be normal pressure, pressurization, or reduced pressure. The atmosphere may be air or an inert atmosphere.

Further, as an imidization accelerator for promoting imidization, a compound having a function of enhancing nucleophilicity and electrophilicity can be added. Specifically, for example, trimethylamine, triethylamine, tripropylamine, tributylamine, triabutanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine , Tertiary amine compounds such as N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline and isoquinoline; carboxylic acids such as 4-hydroxyphenylacetic acid, 3-hydroxybenzoic acid, N-acetylglycine and N-benzoylglycine Compound; Polyhydric phenol compound such as methyl 3,5-dihydroxyacetophenone, methyl 3,5-dihydroxybenzoate, pyrogallol, methyl gallate, ethyl gallate, naphthalene-1,6-diol; 2-hydroxy Pyridine, 3-hydroxypyridine, 4-hydroxypyridine, 4-pyridinemethanol, N, N-dimethylaminopyridine, nicotinaldehyde, isonicotialdehyde, picolinaldehyde, picolinaldehyde oxime, nicotinaldehyde oxime, isonicotinaldehyde oxime, picolinic acid Ethyl, ethyl nicotinate, ethyl isonicotinate, nicotinamide, isonicotinamide, 2-hydroxynicotinic acid, 2,2'-dipyridyl, 4,4'-dipyridyl, 3-methylpyridazine, quinoline, isoquinoline, phenanthroline, 1 , 10-phenanthroline, imidazole, benzimidazole, 1,2,4-triazole and other heterocyclic compounds;

Among these, tertiary amine compounds, carboxylic acid compounds, and heterocyclic compounds are preferable, and triethylamine, imidazole, and pyridine are particularly preferable because they tend to control the imidization rate.
These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations.

The amount of the imidization accelerator used is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, particularly preferably 1 mol% or more based on the carboxyl group or ester group of the amic acid skeleton. Moreover, it is preferable that it is 50 mol% or less, and it is more preferable that it is 10 mol% or less. When the usage-amount of a catalyst exists in such a range, it exists in the tendency for the imidation reaction to advance efficiently and to obtain the polyimide which controlled the imidation ratio. Furthermore, the reaction can be performed at a low cost and with a high yield.
Moreover, the timing which adds an imidation promoter can be adjusted suitably in order to make it a desired imidation rate, may be before a heating start, and may be during a heating. Moreover, you may add in multiple times.

(Chemical imidization)
A polyimide composition can be obtained by chemically imidizing a polyamic acid with a dehydrating condensing agent in the presence of a solvent. The polyimide which is a specific imidization ratio of the present invention has a heating temperature, a heating time, a polyamic acid concentration in a solvent, a type of a dehydrating condensing agent, an amount of adding a dehydrating condensing agent, a timing for adding a dehydrating condensing agent, and the like. It can be obtained by adjusting.
Examples of the solvent used when imidizing the polyamic acid include the same solvents as mentioned in the synthesis of the polyamic acid in the above two-stage method.

Examples of the dehydrating condensing agent include N, N-2-substituted carbodiimides such as N, N-dicyclohexylcarbodiimide and N, N-diphenylcarbodiimide; acid anhydrides such as acetic anhydride and trifluoroacetic anhydride; thionyl chloride and tosyl chloride and the like. Chlorides of: acetyl chloride, acetyl bromide, propionyl iodide, acetyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide, propionyl fluoride, isobutyryl chloride, isobutyryl bromide, isobutyryl iodide, isobuty Ril fluoride, n-butyryl chloride, n-butyryl bromide, n-butyryl iodide, n-butyryl fluoride, mono-chloroacetyl chloride, di-chloroacetyl chloride, Re-chloroacetyl chloride, mono-bromoacetyl chloride, di-bromoacetyl chloride, tri-bromoacetyl chloride, mono-iodoacetyl chloride, di-iodoacetyl chloride, tri-iodoacetyl chloride, mono-fluoroacetyl chloride , Di-fluoroacetyl chloride, tri-fluoroacetyl chloride, chloroacetic anhydride, phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyl iodide, thionyl fluoride, etc .; phosphorus trichloride, triphenyl phosphite And phosphorus compounds such as diethyl phosphate cyanide; and the like.

Among these, acid anhydrides or halogenated compounds are preferable, and acid anhydrides are particularly preferable. By using these, the imidation reaction proceeds efficiently, and a polyimide having a controlled imidation rate tends to be obtained.
These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations.

The amount of these dehydrating condensing agents to be used is usually 0.1 mol or more, preferably 0.2 mol or more, usually 1.0 mol or less, preferably 0.9 mol or less with respect to 1 mol of the amic acid skeleton. By setting the dehydration condensing agent within this range, the imidization rate can be controlled. These can be used alone or in combination of two or more.

Although there is no restriction | limiting in particular in the density | concentration of the polyamic acid at the time of imidation reaction, Usually, 1 mass% or more, Preferably it is 5 mass% or more, Usually, 70 mass% or less, Preferably it is 40 mass% or less. By setting it within this range, the imidation rate can be controlled, production efficiency tends to be high, and the solution viscosity tends to be easy to manufacture.

Although the imidization reaction temperature is not particularly limited, the imidization reaction temperature is not particularly limited as long as it does not depart from the gist of the present invention, but is usually 0 ° C or higher, preferably 10 ° C or higher, more preferably 20 ° C or higher, Usually, it is 150 ° C. or lower, preferably 130 ° C. or lower, more preferably 100 ° C. or lower. It is preferable to carry out in this range since the imidization reaction proceeds efficiently and a polyimide having a controlled imidization rate tends to be obtained. Furthermore, it is preferable because side reactions other than the imidization reaction are suppressed.
The pressure during the reaction may be normal pressure, pressurization, or reduced pressure. The atmosphere may be air or an inert atmosphere.
Moreover, the above-mentioned tertiary amines etc. can also be added similarly to heat | fever imidation as a catalyst which accelerates | stimulates imidation.

(One-step method)
A polyimide composition can be obtained directly from tetracarboxylic dianhydride and a diamine compound using a conventionally known method. In this method, imidization is performed from synthesis of polyamic acid in a two-stage method to imidization without stopping the reaction or isolating an intermediate (polyamic acid).
Similarly to the case of obtaining a polyimide composition from polyamic acid (two-step method), the one-step method can also use the same reaction conditions as those of the heat imidization and chemical imidization.

There is no particular limitation on the one-stage method, but it will be explained in detail below. By adjusting the heating temperature, the heating time, the concentration of tetracarboxylic dianhydride and diamine compound, the type of additive, the amount of additive, the timing of addition, etc. Obtainable.

There are no particular limitations on the order and method of adding tetracarboxylic dianhydride and diamine compound to tetracarboxylic dianhydride and diamine compound. For example, a polyimide composition can be obtained by adding a tetracarboxylic dianhydride and a diamine compound to a solvent in this order and stirring at a temperature at which the reaction until imidization proceeds.

The amount of the diamine compound is usually 0.7 mol or more, preferably 0.8 mol or more, and usually 1.3 mol or less, preferably 1.2 mol or less, relative to 1 mol of tetracarboxylic dianhydride. is there. By setting the amount of the diamine compound in such a range, it is possible to obtain a polyimide with a controlled imidation rate, and the yield of the resulting polyimide composition tends to be improved.

The concentration of tetracarboxylic dianhydride and diamine compound in the solvent can be set as appropriate for each condition and viscosity during polymerization, but the total mass of tetracarboxylic dianhydride and diamine compound is a special setting. However, it is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less, based on the total liquid amount. If the concentration in the solvent is too low, elongation of the molecular weight hardly occurs, and if it is too high, the viscosity becomes too high and stirring becomes difficult. Moreover, it exists in the tendency which can obtain the polyimide which controlled the imidation ratio because it is the said range.
Examples of the solvent used in this reaction include the same solvents as those described above.

1.5 Production method of polyimide composition The obtained polyimide may be used as it is as a polyimide composition, or after being precipitated in a solid state by adding it to a poor solvent, it is redissolved in another solvent. It can also be used as a polyimide composition.

The poor solvent at this time is not particularly limited and may be appropriately selected depending on the type of polyimide, but ether solvents such as diethyl ether and diisopropyl ether; ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone, and methyl isobutyl ketone; methanol, Examples thereof include alcohol solvents such as ethanol and isopropyl alcohol. Among them, alcohol solvents such as isopropyl alcohol are preferable in that precipitates can be obtained efficiently, the boiling point is low, and drying is easy. These solvents may be used alone or in combination of two or more in any ratio and combination.
Moreover, the solvent of the polyimide composition mentioned above is mentioned as a solvent which redissolves a polyimide.

In the polyimide composition of the present invention, an imidizing agent can be added to the polyimide composition in order to further increase the imidization rate when forming the alignment film.
The imidizing agent is not particularly limited as long as it promotes imidization, and the above-mentioned imidization accelerator can be used. Preferred are carboxylic acid compounds or heterocyclic compounds, more preferred are heterocyclic compounds, and more preferred are 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine, N, N-dimethylaminopyridine, nicotine. Amides, isonicotinamides, imidazoles, benzimidazoles and 1,2,4-triazoles.
These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations. Moreover, addition of said compound may be added at the time of manufacture of a polyimide composition, and may be added just before application | coating.

In the polyimide composition of the present invention, a coupling agent such as a silane coupling agent or a titanium coupling agent can be added in order to adjust the adhesiveness to the coated body. These compounds may be used individually by 1 type, or may be used 2 or more types by arbitrary ratios and combinations. The amount used at this time is preferably 0.1% by mass or more and 3% by mass or less with respect to the polyimide.

Examples of the silane coupling agent include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltributoxysilane, γ-aminoethyltriethoxysilane, γ -Aminoethyltrimethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltributoxysilane, γ-aminobutyltriethoxysilane, γ-aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-amino Examples include butyltributoxysilane.

Examples of the titanium coupling agent include γ-aminopropyltriethoxytitanium, γ-aminopropyltrimethoxytitanium, γ-aminopropyltripropoxytitanium, γ-aminopropyltributoxytitanium, γ-aminoethyltriethoxytitanium, γ -Aminoethyltrimethoxytitanium, γ-aminoethyltripropoxytitanium, γ-aminoethyltributoxytitanium, γ-aminobutyltriethoxytitanium, γ-aminobutyltrimethoxytitanium, γ-aminobutyltripropoxytitanium, γ-amino Examples thereof include butyl tributoxy titanium.

In addition, various additives can be blended as necessary. For example, other powdery, granular, plate-like, fiber-like inorganic fillers and organic fillers can be blended within a range not impairing the effects of the present invention.

Further, these fillers may be processed into a flat shape such as a non-woven fabric or may be used in combination. Furthermore, if desired, various additives commonly used in resin compositions such as lubricants, colorants, stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, plasticizers, mold release agents, etc. Can be blended. These various fillers and additive components may be added at any stage of any process for producing polyimide. *

According to the present invention, there is provided an optical element comprising an alignment film formed from the polyimide composition, an anisotropic dye film formed from the alignment film and a dye. Hereinafter, these inventions will be described in more detail.

1.6 Alignment Film Formation Method and Alignment Film The alignment film of the present invention can be formed by applying the polyimide composition of the present invention to an object to be coated.
The application method is not particularly limited as long as it can form a layer having a uniform thickness. For example, die coating, spin coating, screen printing, flexographic printing, spraying, a casting method using an applicator; a method using a coater; The method by spraying; immersion method; calendar method; casting method;

As the coated body, for example, a substrate including glass such as float glass or soda glass; plastic such as polyethylene terephthalate, polycarbonate, polyolefin, or the like can be used. When applying the polyimide composition of the present invention, a functional silane-containing compound or a functional titanium-containing compound can be applied in advance to the surface of the substrate, which is an object to be coated. Further, ultraviolet treatment, plasma treatment, or the like can be performed.

The method for volatilizing the solvent of the polyimide composition is not particularly limited. Usually, a solvent is volatilized by heating the to-be-coated body to which the polyimide composition is applied. The heating method is not particularly limited, and examples thereof include hot air heating, vacuum heating, infrared heating, microwave heating, heating by contact using a hot plate or a hot roll, and the like.

The heating temperature in drying the solvent of the applied polyimide composition can be a suitable temperature depending on the type of the solvent, but is usually 20 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher. is there. Further, it is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 150 ° C. or lower. When the solvent removal temperature is 20 ° C. or higher, it is preferable in that the solvent is sufficiently volatilized. Moreover, when solvent removal temperature is 200 degrees C or less, the performance fall of each material at the time of forming alignment film in to-be-coated bodies, such as a low heat resistant material, for example, polyester resin, polyolefin resin, etc. can be suppressed.

After application, in order to further increase the imidation ratio of the alignment film, it may be further heated. The temperature for increasing the imidization rate is preferably 60 ° C or higher, more preferably 80 ° C or higher. Further, it is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 150 ° C. or lower. A heating temperature of 60 ° C. or higher is preferable because imidization proceeds efficiently and the remaining amount of amic acid that causes hydrolysis and the like decreases. Moreover, when heating temperature is 200 degrees C or less, it exists in the tendency which can suppress the performance fall of each material at the time of forming alignment film in to-be-coated bodies, such as a low heat resistant material, for example, polyester resin, polyolefin resin.
The solvent removal temperature and the temperature for increasing the imidization rate may be different from each other or the same temperature. Moreover, when performing the heating for raising a solvent removal and imidation rate, each heating method may differ or may be the same.

The thickness of the alignment film obtained can be controlled by adjusting the coating amount of the polyimide composition. The thickness of the alignment film is usually 1 nm or more, preferably 10 nm or more, and is usually 10 μm or less, preferably 5 μm or less, more preferably 2 μm or less, and particularly preferably 1 μm or less. When the thickness is 1 nm or more, the uniformity of the film thickness at the time of forming the alignment film is increased, and the alignment film can have sufficient alignment characteristics. Moreover, it is preferable to make the thickness 10 μm or less because the liquid crystal cell can be thinned.

The hardness of the alignment film prepared from the polyimide composition of the present invention is such that the Vickers hardness at a film thickness of 2 μm is usually 10 or more, preferably 20 or more, more preferably 30 or more. Moreover, it is 100 or less normally, Preferably it is 80 or less, More preferably, it is 60 or less. When the Vickers hardness is in a specific range, scratches hardly occur on the alignment film, and application defects of the anisotropic dye film due to scratches on the alignment film tend to be prevented. Further, when a surface treatment such as a rubbing treatment of the alignment film is performed, the relaxation becomes slow and the surface treatment effect tends to be obtained.

The Vickers hardness can be measured as follows using a microhardness meter HM2000 (Fischer Instruments).
As the indenter, a Vickers indenter is used. A load of 5 mN / μm ² is applied at a load speed of 1.67 mN / sec. After holding for 5 seconds, the load is removed to obtain a Vickers hardness (Martens hardness × 0.0945).

The elastic deformation rate of the alignment film prepared with the polyimide composition of the present invention is usually 10% or more, preferably 15% or more, more preferably 18% or more, as determined by a microhardness meter at a film thickness of 2 μm. Yes, particularly preferably 20% or more. Moreover, it is 70% or less normally, Preferably it is 65% or less. When the elastic change rate of the alignment film is within this range, it becomes difficult to relax when surface treatment such as rubbing is performed, and the surface treatment such as rubbing can be maintained, and the orientation characteristics tend to be maintained. When rubbing is performed, the alignment film is less likely to be scraped or scratched by rubbing, and a uniform alignment film tends to be obtained.

The transmittance of the alignment film prepared from the polyimide composition of the present invention is usually 60% or more, preferably 70% or more, more preferably 80% or more on the longer wavelength side (visible region) from 400 nm. There is no particular upper limit on the transmittance, and a higher one is preferable.
An alignment film having a high light transmittance is preferably used in a device or the like that requires translucency. In particular, when used in a liquid crystal display, it is desirable that the transmittance of the blue region of the backlight is high, and specifically, it is preferable to have the above transmittance on a longer wavelength side than 420 nm. As the transmittance of the alignment film prepared from the polyimide composition of the present invention, the total light transmittance according to JIS K 7136-1 is used.

In order to improve the alignment characteristics of the alignment film, a rubbing process in which the coated surface obtained above is rubbed in a certain direction with a roll wrapped with a cloth containing fibers such as nylon, rayon, and cotton, and a process of irradiating linearly polarized light. Etc. can be performed. By performing these treatments, an alignment film having higher alignment characteristics can be obtained.
Among them, it is preferable to enhance the alignment characteristics by rubbing treatment in order to align the anisotropic dye film described later. When this rubbing treatment is performed on the alignment film and the anisotropic dye is aligned, it is necessary to perform the rubbing treatment more strongly than the liquid crystal alignment film. For this reason, the conventional alignment film for liquid crystal is scraped by rubbing, and there may be a defect in the anisotropic dye film due to process contamination due to scraping and damage to the alignment film caused by scraping.

When the water-soluble dichroic dye is applied to the surface-treated alignment film, the contact angle of the alignment film is usually 70 ° or less, preferably 60 ° or less, and more preferably 50 ° or less. When the contact angle is within an appropriate range, the dye solution tends to be uniformly applied without repelling the dye solution.

1.7 Anisotropic Dye Film Composition An anisotropic dye film composition is in a liquid crystal phase as a composition, and an anisotropic dye film formed after evaporation of the solvent has a high degree of orientation. It is preferable from a viewpoint of forming. In this embodiment, the state of the liquid crystal phase means that the liquid crystal phase is liquid as described on pages 1 to 16 of “Basics and Applications of Liquid Crystal” (Shoichi Matsumoto, Ryo Tsunoda, 1991). It is a liquid crystal state exhibiting both properties of crystal and crystal, and it means a nematic phase, a cholesteric phase, a numeric phase or a discotic phase. A nematic phase is particularly preferable.
Moreover, binder resin, a monomer, a hardening | curing agent, an additive, etc. may be mix | blended with the composition for anisotropic dye films | membranes as needed. The anisotropic dye film composition may be in the form of a solution or gel. The composition for anisotropic dye film may be in a state in which a dye or the like is dissolved or dispersed in a solvent.

(Dye)
As the dye, a dichroic dye is usually used. Examples of the dichroic dye include a dye expressing a lyotropic liquid crystal, a dye expressing a thermotropic liquid crystal, and the like, and any of them may be used.
In the present invention, the dye is preferably a dye having a liquid crystal phase for alignment control. Here, the dye having a liquid crystal phase means a dye that exhibits lyotropic liquid crystallinity in a solvent, and may or may not exhibit a liquid crystal phase when the composition for an anisotropic dye film is formed. Although it is good, the liquid crystal phase is preferable as described above.

In addition, the dye used in the present invention may be soluble in water or an organic solvent so that the anisotropic dye film composition exhibits a liquid crystal phase and is used for a wet film-forming method described later. Particularly preferred is water solubility. Further preferred are compounds having an inorganic value smaller than the organic value as defined in “Organic Conceptual Diagram-Fundamentals and Applications” (Yoshio Koda, Sankyo Publishing, 1984). Further, in a free state that does not take a salt form, the molecular weight is preferably 200 or more, particularly preferably 300 or more, more preferably 1500 or less, and particularly preferably 1200 or less. . The term “water-soluble” means that the compound is usually dissolved in water at 0.1% by mass or more, preferably 1% by mass or more at room temperature.

In the composition for anisotropic dye film of the present invention, only one kind of dye may be used, or two or more kinds may be used in combination. When two or more types are combined, in order for the anisotropic dye film composition to exhibit a liquid crystal phase, it is sufficient that at least one type is a pigment that exhibits a liquid crystal phase.

Specific examples of the dye include azo dyes, stilbene dyes, cyanine dyes, phthalocyanine dyes, and condensed polycyclic dyes (perylene and oxazine dyes).

The dye used in the present invention is not particularly limited, and the following known dyes can be used.
Examples of the dye include, for example, Japanese Unexamined Patent Publication No. 2006-0799030, Japanese Unexamined Patent Publication No. 2010-168570, Japanese Unexamined Patent Publication No. 2007-302807, Japanese Unexamined Patent Publication No. 2008-081700, Japanese Unexamined Patent Publication No. 09-230142, Japan 2007-722211, Japan 2007-186428, Japan 2008-69300, Japan 2009-169341, Japan JP 2009-161722, JP 2009-173849, JP 2010-039154, JP 2010-180314, JP 2010-266769, JP No. 2010-031268, Japanese Unexamined Patent Publication No. 2011-012152, Japanese Special No. 2011-016922, Japanese Unexamined Patent Publication No. 2010-100059, Japanese Unexamined Patent Publication No. 2011-141331, Japanese Unexamined Patent Publication No. 2011-190313, Japanese National Specification No. 08-511109, Japanese Special Publication Table 2001-504238, Japanese Unexamined Patent Publication No. 2006-48078, Japanese Unexamined Patent Publication No. 2006-98927, Japanese Unexamined Patent Publication No. 2006-193722, Japanese Unexamined Patent Publication No. 2006-206878, Japanese Special JP 2005-255846, JP 2007-145995, JP 2007-126628, JP 2008-102417, JP 2012-194357, JP 2012-194297, Japan JP2011-034061, JP, Japan JP 2009-110902 and JP Japanese Patent 2011-100059, JP Japanese Patent 2012-194365 JP include dyes described in Japanese Patent 2011-016920 Patent Publication.

The above dye is suitable as a dye for an anisotropic dye film formed by a wet film forming method, has low wavelength dispersibility, and has a high degree of polarization and dichroic ratio. Moreover, since the said pigment | dye is excellent in compatibility with the orientation film formed from the polyimide composition of this invention, it exists in the tendency which can obtain the anisotropic pigment | dye film | membrane which shows a high degree of molecular orientation.
Furthermore, it is preferable to use an azo dye among these dyes because it is particularly excellent in compatibility with an alignment film formed from the polyimide composition of the present invention. An azo dye means a dye having at least one azo group. The number of azo groups in one molecule is preferably 2 or more, and preferably 6 or less. Further, 4 or less is more preferable. When the azo group is in an appropriate number, the wavelength dispersion is low, a color tone having absorption in a wide range in the visible region is obtained, and the production tends to be easy.

Among the azo dyes, each of the disazo, trisazo and tetrakisazo dyes having the structure of the following general formula (A) in the form of a free acid is compatible with the alignment film formed from the polyimide composition of the present invention. It is preferable because an anisotropic dye film having excellent molecular orientation and a high degree of molecular orientation can be obtained. Furthermore, the dye having the structure of the general formula (A) is preferable because it has a low wavelength dispersibility and a color tone having absorption in a wide range in the visible region is obtained.

In the general formula (A), E ¹ represents an arbitrary organic group, and R ²⁰ and R ²¹ each independently have a hydrogen atom, an alkyl group which may have a substituent, or a substituent. And p and q each independently represent an integer of 1 or more and 5 or less, and the sum of p and q represents 2 or more and 6 or less.

Further, among the structures of the above general formula (A), each of the disazo, trisazo and tetrakisazo dyes having the structure of the following general formula (B) in the form of a free acid is formed from the polyimide composition of the present invention. An anisotropic dye film having excellent compatibility with the film and showing a high degree of molecular orientation can be obtained, which is more preferable. Moreover, the pigment | dye which has a structure of general formula (B) is especially preferable from the color dispersion which has a low wavelength dispersion property and has absorption in a visible region widely.

In the general formula (B), E ² represents an arbitrary organic group, and R ²² and R ²³ each independently have a hydrogen atom, an alkyl group which may have a substituent, or a substituent. Represents an optionally substituted phenyl group.

Hereinafter, examples of pigments (specific compounds) used in the present invention are exemplified, but the present invention is not limited thereto.

The dye in the present embodiment may be used in the form of a free acid, or a part of the acid group may have a salt form. Further, a salt-type dye and a free acid-type dye may be mixed. Moreover, when it is obtained in a salt form at the time of production, it may be used as it is or may be converted into a desired salt form. As the salt-type exchange method, a known method can be arbitrarily used, and examples thereof include the following methods.

1) A strong acid such as hydrochloric acid is added to an aqueous solution of a dye obtained in a salt form, the dye is acidified in the form of a free acid, and then the dye is added with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). A method of neutralizing acidic groups and salt exchange.
2) A method of performing salt exchange in the form of a salting-out cake by adding a large excess of a neutral salt (eg, lithium chloride) having a desired counter ion to an aqueous dye solution obtained in a salt form.
3) An aqueous solution of a dye obtained in a salt form is treated with a strongly acidic cation exchange resin, and the dye is acidified in the form of a free acid, and then an alkali solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). ) To neutralize the acidic group of the dye and perform salt exchange.
4) A method of performing salt exchange by allowing an aqueous solution of a dye obtained in a salt form to act on a strongly acidic cation exchange resin previously treated with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution).

Whether the acidic group of the dye in the present embodiment is a free acid type or a salt type depends on the pKa of the dye and the pH of the aqueous dye solution.
Examples of the salt type include salts of alkali metals such as Na, Li and K, ammonium salts which may be substituted with alkyl groups or hydroxyalkyl groups, and organic amine salts. Examples of the organic amine include a lower alkyl amine having 1 to 6 carbon atoms, a hydroxy-substituted lower alkyl amine having 1 to 6 carbon atoms, a carboxy-substituted lower alkyl amine having 1 to 6 carbon atoms, and the like. In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed.

The above dyes can be used alone, but two or more of these may be used in combination, and dyes other than the above exemplified dyes may be blended and used to such an extent that the orientation is not lowered. Thereby, anisotropic dye films having various hues can be produced.

Examples of blending pigments when blending other pigments include C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 34, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 142, C.I. I. Direct Yellow 132, C.I. I. Acid Yellow 25, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Orange 79, C.I. I. Acid Orange 28, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Acid Red 37, C.I. I. Direct Violet 9, C.I. I. Direct Violet 35, C.I. I. Direct Violet 48, C.I. I. Direct Violet 57, C.I. I. Direct Blue 1, C.I. I. Direct Blue 67, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Green 42, C.I. I. Direct Green 51, C.I. I. Direct Green 59 etc. are mentioned.

An anthraquinone compound may be blended in the anisotropic dye film composition of the present invention in accordance with the methods described in Japanese Patent Application Publication No. 2007-199333 and Japanese Patent Application Publication No. 2008-101154. Furthermore, the methods described in Japanese Unexamined Patent Publication No. 2006-3864 and Japanese Unexamined Patent Publication No. 2006-323377 may be used.
In addition, the composition for anisotropic dye film of the present invention has a temperature of 5 ° C. for an anisotropic dye film composition and 0.01% after strain application as described in Japanese Patent Application Laid-Open No. 2007-179933. The defect of the anisotropic dye film may be controlled by setting the time until the relaxation elastic modulus G after 1 second is reduced to 1/10 to 0.1 second or less. Specifically, the cation is 0.9 equivalent or more and 0.99 equivalent or less and the strongly acidic anion is 0.02 equivalent or more with respect to the acidic group of the azo compound in the composition for anisotropic dye film. , 0.1 equivalent or less is included.

(Solvent of composition for anisotropic dye film)
The solvent is not particularly limited as long as it dissolves or disperses the above compound. In particular, water, a water-miscible organic solvent, or a mixture thereof is suitable because the dye easily forms an association state such as a lyotropic liquid crystal in the solvent. Specific examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and glycerin, glycols such as ethylene glycol and diethylene glycol, and cellosolves such as methyl cellosolve and ethyl cellosolve, or a mixture of two or more. A solvent is mentioned.
Among these, water, methanol, and ethanol are preferable, and water is particularly preferable because it promotes association between highly organic portions such as an aromatic ring of the dye.

(Dye concentration in anisotropic dye film composition)
The concentration of the dye in the composition for anisotropic dye film is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 50% by mass, although it depends on the film forming conditions. Hereinafter, it is more preferably 30% by mass or less. If the dye concentration is excessively low, the association of the dyes in the composition becomes insufficient, and the anisotropic dye film obtained cannot obtain anisotropy such as a sufficient degree of polarization and dichroic ratio. If it is too high, the viscosity becomes so high that it is difficult to apply a uniform thin film, or the dye may precipitate in the composition for anisotropic dye film.

(Additive of composition for anisotropic dye film)
The anisotropic dye film composition may further contain additives such as a surfactant, a leveling agent, a coupling agent, and a pH adjuster as necessary. Depending on the additive, wettability, applicability and the like may be improved.
As the surfactant, any of anionic, cationic and nonionic properties can be used. The addition concentration is not particularly limited, but is usually sufficient as the concentration in the anisotropic dye film composition as an amount that is sufficient to obtain the added effect and does not inhibit the orientation of the molecule. 0.01 mass% or more is preferable and 0.1 mass% or more is further more preferable. Moreover, 5 mass% or less is preferable, 1 mass% or less is more preferable, 0.5 mass% or less is especially preferable.

In addition, for the purpose of suppressing instability such as salt formation and aggregation of the dye in the composition for anisotropic dye film, a known pH adjuster such as acid / alkali is added to the anisotropic dye. It may be added either before or after mixing the components of the film composition or during mixing. As additives other than the above, “Additive for Coating”, Edited by J. Known additives described in Bieleman, Willy-VCH (2000) can also be used.

1.8 Method for Forming Anisotropic Dye Film In the present invention, an anisotropic dye film is preferably formed on the alignment film of the present invention by a wet film formation method.
The wet film-forming method referred to in the present invention is a method in which an anisotropic dye film composition is applied to an alignment film by any method, and a dye is aligned and laminated on a substrate through a process of drying a solvent. is there. In the wet film formation method, when the anisotropic dye film composition is formed on the substrate, the dye itself self-associates in the anisotropic dye film composition or in the process of drying the solvent. Causes orientation in a small area. By applying an external field to this state, an anisotropic dye film having desired performance can be obtained by orienting in a certain direction in a macro region. This is different from the method based on the principle that a so-called polyvinyl alcohol (PVA) film or the like is dyed with a solution containing a dye and stretched, and the dye is oriented only by a stretching process. Here, the external field includes the influence of the orientation treatment layer previously applied on the base material, shear force, magnetic field, etc., and these may be used alone or in combination.

In addition, the process of forming the composition for an anisotropic dye film on the substrate, the process of aligning by applying an external field, and the process of drying the solvent may be performed sequentially or simultaneously.
Examples of the method for applying the anisotropic dye film composition on the substrate in the wet film forming method include a coating method, a dip coating method, an LB film forming method, a known printing method, and the like. There is also a method of transferring the anisotropic dye film thus obtained to another substrate. Among these, the present invention preferably uses a coating method. Specifically, the anisotropic dye film can be formed by applying the anisotropic dye film composition to the alignment film.
The orientation direction of the anisotropic dye film is usually coincident with the application direction, but may be different from the application direction. In the present embodiment, the orientation direction of the anisotropic dye film is, for example, a transmission axis or absorption axis of polarized light in the case of an anisotropic dye film, and a fast axis or in the case of a retardation film. It is the slow axis.

The anisotropic dye film in the present embodiment functions as a polarizing film or retardation film that obtains linearly polarized light, circularly polarized light, elliptically polarized light, etc. by utilizing the anisotropy of light absorption, as well as film forming processes and coatings. By selecting a composition containing an applied body (substrate or the like) or an organic compound (colorant or transparent material), it can be functionalized as various anisotropic films such as refractive anisotropy and conduction anisotropy.

The method for applying the anisotropic dye film composition to obtain the anisotropic dye film is not particularly limited. For example, Yuji Harasaki "Coating Engineering" (Asakura Shoten Co., Ltd., issued March 20, 1971) ) Methods described on pages 253 to 277, supervised by Kunihiro Ichimura, “Creation and Application of Molecular Coordination Materials” (CMC Publishing Co., Ltd., published on March 3, 1998), pages 118 to 149, Examples of the method include coating on the coated body by a slot die coating method, a spin coating method, a spray coating method, a bar coating method, a roll coating method, a blade coating method, a curtain coating method, a fountain method, and a dip method. Among these, the slot die coating method is preferable because an anisotropic dye film with high uniformity can be obtained.
On the alignment film of the present invention, when applying the anisotropic dye film composition that expresses a preferable lyotropic liquid crystal phase as the above-mentioned anisotropic dye film composition by the above-described application method, It is considered that the dye is oriented by the influence of the orientation treatment of the orientation film or the like previously applied on the substrate and the shearing force applied to the anisotropic dye film composition at the time of application.

The method for supplying the composition for anisotropic dye film and the supply interval when applying the composition for anisotropic dye film continuously are not particularly limited, but the operation of supplying the coating liquid becomes complicated, or the coating liquid When the anisotropic dye film is thin, especially while supplying the composition for the anisotropic dye film continuously, the coating film thickness may vary at the start and stop of It is desirable to apply. *

The speed at which the composition for anisotropic dye film is applied is usually 1 mm / second or more, preferably 5 mm / second or more, more preferably 10 mm / second or more. Moreover, it is 1000 mm / sec or less normally, Preferably it is 200 mm / sec or less. It is. If the coating speed is too small, the anisotropy of the anisotropic dye film may be lowered. On the other hand, when too large, there exists a possibility that it cannot apply | coat uniformly.
In addition, as application | coating temperature of the composition for anisotropic dye films, it is 0 degreeC or more and 80 degrees C or less normally, Preferably it is 40 degrees C or less. Moreover, the humidity at the time of application | coating of the composition for anisotropic dye films becomes like this. Preferably it is 10% RH or more, More preferably, it is 30% RH or more, Preferably it is 80 RH% or less.

The film thickness of the anisotropic dye film is preferably 10 nm or more, more preferably 50 nm or more as a dry film thickness. On the other hand, it is preferably 30 μm or less, more preferably 1 μm or less. When the film thickness of the anisotropic dye film is in an appropriate range, there is a tendency that uniform orientation of molecules and a uniform film thickness can be obtained in the film.

The anisotropic dye film may be insolubilized. Insolubilization means a treatment step that increases the stability of the film by controlling the elution of the compound from the anisotropic dye film by reducing the solubility of the compound in the anisotropic dye film. Specifically, for example, an ion with a lower valence is replaced with an ion with a higher valence (for example, a monovalent ion is replaced with a polyvalent ion), or an organic molecule or polymer having a plurality of ionic groups. A replacement process is listed. As such a treatment method, for example, known methods such as treatment steps described in Yutaka Hosoda, “Theoretical Manufacturing, Dyeing Chemistry” (Gihodo, 1957), pages 435 to 437 can be used.
Preferably, the obtained anisotropic dye film is treated by a method described in Japanese Patent Application Laid-Open No. 2007-241267, etc. to obtain an anisotropic dye film insoluble in water. It is preferable from the viewpoint of ease and durability.
The transmittance of the anisotropic dye film in the visible light wavelength region is preferably 25% or more. 35% or more is more preferable, and 40% or more is particularly preferable. Moreover, there is no upper limit in particular in the transmittance | permeability, What is necessary is just an upper limit according to a use. For example, when used for a liquid crystal display, it is preferably 50% or less.

When the anisotropic dye film of the present invention is used as a polarizing element, the orientation characteristic of the anisotropic dye film can be expressed by the degree of polarization. The degree of polarization is such that the single transmittance is 36% or more and is usually 95% or more, preferably 98% or more, and more preferably 99% or more. Moreover, the higher the degree of polarization, the better. The maximum value is 100%. When the degree of polarization is not less than the above numerical value, it is useful as the following optical element, particularly as a polarizing element.
Each transmittance is not particularly limited as long as it has the same wavelength, and any wavelength may be selected depending on the purpose. However, when expressing the degree of orientation of the anisotropic dye film, the maximum of the anisotropic dye film is used. The value at the absorption wavelength is preferably used.
Polarization degree (P) (%) = {(Ty−Tz) / (Ty + Tz)} ^1/2 × 100
Tz: transmittance for polarized light in the direction of the absorption axis of the anisotropic dye film Ty: transmittance for polarized light in the direction of the polarization axis of the anisotropic dye film

The above-mentioned anisotropic dye or the composition for anisotropic dye film can be directly added to the polyimide composition of the present invention to be used as an anisotropic dye film. Each condition in this case can be performed in the same manner as the method for forming the anisotropic dye film.

1.9 Optical Element The optical element of the present invention is a polarizing element that obtains linearly polarized light, circularly polarized light, elliptically polarized light, etc., utilizing retardation of light absorption, a retardation element, refractive anisotropy, conductive anisotropy, etc. It is an element having a function. These functions can be appropriately adjusted depending on the film forming process and the selection of a composition containing an object to be coated (substrate or the like) or an organic compound (pigment or transparent material). In the present invention, it is preferably used as a polarizing element.

1.10 Polarizing Element The polarizing element of the present invention has any other film (layer) as long as it has an alignment film and an anisotropic dye film composition on an object to be coated (substrate or the like). It may be a thing. For example, it can be produced by forming an anisotropic dye film composition on the surface of the alignment film. The polarizing element of the present invention is an overcoat layer, an adhesive layer or an antireflection layer, an alignment film, a function as a retardation film, a function as a brightness enhancement film, if necessary, in addition to the alignment film and the anisotropic dye film. Layers with various functions such as a function as a reflection film, a function as a transflective film, a layer with optical functions such as a diffusion film, etc. are laminated by coating or bonding, and used as a laminate. May be.
These layers having an optical function can be formed, for example, by the following method.
The layer having a function as a retardation film is subjected to stretching treatment described in, for example, Japanese Patent Application Laid-Open No. 2-59703, Japanese Patent Application Laid-Open No. 4-230704, or Japanese Patent Application Laid-Open No. 7-230007. It can be formed by performing the treatment described in the above.

Further, the layer having a function as a brightness enhancement film may be formed with micropores by a method as described in, for example, Japanese Patent Application Laid-Open No. 2002-169025 or Japanese Patent Application Laid-Open No. 2003-29030, or It can be formed by overlapping two or more cholesteric liquid crystal layers having different central wavelengths of selective reflection.

The layer having a function as a reflective film or a transflective film can be formed using a metal thin film obtained by vapor deposition, sputtering, or the like. The layer having a function as a diffusion film can be formed by coating the protective layer with a resin solution containing fine particles.

The layer having a function as a retardation film or an optical compensation film can be formed by applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound.

When the anisotropic dye film in the present embodiment is used as an anisotropic dye film or the like for various display elements such as LCDs and OLEDs, an alignment film directly on the surface of the electrode substrate or the like constituting these display elements An anisotropic dye film can be formed, or a substrate on which an alignment film and an anisotropic dye film are formed can be used as a constituent member of these display elements.
Since the optical element of the present invention can be directly formed on a highly heat-resistant coated body (substrate or the like) such as glass, a highly heat-resistant polarizing element can be obtained, so that a liquid crystal display or an organic electroluminescence display can be obtained. In addition, it can be suitably used for applications that require high heat resistance, such as liquid crystal projectors and in-vehicle display panels.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless it is contrary to the gist thereof. The values of various conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiment of the present invention, and the preferred range is the above upper limit or lower limit value. It may be a range defined by a combination of values of the examples or values between the examples.

<Aromatic ring element ratio>
It calculated from the ratio of the aromatic tetracarboxylic anhydride and diamine compound in a raw material monomer.

<Imidization rate>
The imidation ratio of the synthesized polyimide composition was measured as follows using FT-IR (6100 manufactured by JASCO Corporation).
First, the polyimide composition was applied to potassium bromide crystals, and a sample dried at 300 ° C. was prepared in the same manner as the sample dried at 70 ° C.
Absorption around 1500 cm ^{−1 of the} 300 ° C. dried sample (A), absorption around 1380 cm ⁻¹ (B), absorption around 1500 cm ⁻¹ of the 70 ° C. dried sample (A ′), absorption around 1380 cm ⁻¹ (B ′ ) And the imidation ratio (%) of each polyimide composition was calculated from the following formula.
Imidation rate = (A ′ / B ′) / (A / B) * 100

<Soluble>
The polyimide composition containing the reaction solution was determined as “x” when the solid content (insoluble polyimide resin) was precipitated at room temperature, and “◯” when completely dissolved.

<Vickers microhardness meter measurement>
The solid concentration of the synthesized polyimide compositions 1 to 3 was diluted to 15% by weight to obtain a coating solution. 7 This coating solution was applied to a glass substrate using a spin coater, heated at 80 ° C. for 10 minutes, and further heated at 140 ° C. for 1 hour. The film thickness at this time was 2 μm.
Using this film, a Vickers micro hardness tester HM2000 (manufactured by Fischer Instruments) is used. The indenter is a Vickers indenter. A load of 5 mN / μm ² is applied at a load speed of 1.67 mN / sec and held for 5 seconds. Thereafter, the load was removed, and Vickers hardness (Martens hardness × 0.0945), elastic change rate: (total deformation−plastic deformation) / total deformation × 100 were obtained.

(Synthesis of polyimide composition)
[Example 1]
1,1'-bicyclohexane-3,3 ', 4,4'-tetracarboxylic dianhydride was added to a four-necked flask equipped with a refluxing nitrogen gas introduction ring, a condenser, a Dean-Stark agglomerator filled with toluene, and a stirrer. 6.9 g of the product, 9.4 g of 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 58 g of N, N-dimethylacetamide, and 10.7 g of toluene were added. The mixture was heated with stirring and reacted at 140-150 ° C. for 13 hours to obtain a polyimide composition 1.
About the obtained polyimide composition 1, the aromatic ring element ratio, the imidation ratio, and the solubility were calculated | required by the said method. The results are shown in Table 1.

[Example 2]
Synthesis was performed in the same manner as in Example 1 except that 2,2-bis (4- (4-aminophenoxy) phenyl) propane of Example 1 was changed to 4.6 g of 4,4′-diaminodiphenyl ether. A polyimide composition 2 was obtained. About the obtained polyimide composition 2, it evaluated by the method similar to Example 1. FIG. The results are shown in Table 1.

[Example 3]
Example 2, except that 2,2-bis (4- (4-aminophenoxy) phenyl) propane in Example 1 was changed to 4.8 g of 4,4′-diamino-2,2′-dimethylbiphenyl. Synthesis was performed in the same manner to obtain a polyimide composition 3. About the obtained polyimide composition 3, it evaluated by the method similar to Example 1. FIG. The results are shown in Table 1.

[Example 4]
In a four-necked flask equipped with a reflux nitrogen gas inlet tube, a condenser, a Dean-Stark agglomerator filled with toluene, and a stirrer, 13.3 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride, pyromerit 1.5 g of acid dianhydride, 14.0 g of 3,4-diaminodiphenyl ether, 86 g of N-methyl-2-pyrrolidone and 17.3 g of toluene were added. The mixture was heated with stirring and reacted at 160 to 170 ° C. for 13 hours to obtain a polyimide composition 4. About the obtained polyimide composition 4, it evaluated by the method similar to Example 1. FIG. The results are shown in Table 1.

[Example 5]
To 15.714 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride of Example 4, 3,714 ', 4,4'-biscyclohexanetetracarboxylic dianhydride was added 3,4-diaminodiphenyl ether. 25.949 g of bis (4- (4-aminophenoxy) phenyl) sulfone, 1.243 g of pyromellitic dianhydride, 82 g of N-methyl-2-pyrrolidone, and 16.3 g of toluene were changed. The polyimide composition 5 was obtained by synthesizing in the same manner as in Example 4. The obtained polyimide composition 5 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
1,2,4,5-cyclohexanetetracarboxylic dianhydride of Example 4 to 9.982 g of 1,2,3,4-cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride to 0 g, A polyimide composition 6 was obtained by synthesizing in the same manner as in Example 4, except that the amount of 3,4-diaminodiphenyl ether was changed to 10.12 g, N-methyl-2-pyrrolidone was changed to 60 g, and toluene was changed to 12 g. It was. The obtained polyimide composition was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
The 1,2,4,5-cyclohexanetetracarboxylic dianhydride of Example 4 was added to 12.63 g of 1,1′-bicyclohexane-3,3 ′, 4,4′-tetracarboxylic dianhydride. Example 4 except that melitric anhydride was changed to 1.0 g, 3,4-diaminodiphenyl ether was changed to 9.66 g, N-methyl-2-pyrrolidone was changed to 70.10 g, and toluene was changed to 10.5 g. Was synthesized in the same manner as above to obtain a polyimide composition 7. About the obtained polyimide composition 7, it evaluated by the method similar to Example 1. FIG. The results are shown in Table 1.

[Comparative Example 1]
The 1,1′-bicyclohexane-3,3 ′, 4,4′-tetracarboxylic dianhydride of Example 2 was converted to 6.7 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. Except having changed, it synthesize | combined by the method similar to Example 2, and the polyimide composition 8 was obtained. About the obtained polyimide composition 8, it measured by the method similar to Example 1. FIG. The polyimide composition 8 was not soluble. Moreover, since it was not soluble, the imidation ratio could not be measured. The results are shown in Table 1.

[Comparative Example 2]
The 1,2,4,5-cyclohexanetetracarboxylic dianhydride of Example 4 was changed to 4.2 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and pyromellitic dianhydride was changed to 0 g. Same as Example 4 except that 3,4-diaminodiphenyl ether was changed to 4.8 g of 4,4-diamino-2,2-dimethylbiphenyl, 27 g of N-methyl-2-pyrrolidone, and 5.4 g of toluene. Thus, a polyimide composition 9 was obtained. About the obtained polyimide composition 9, it measured by the method similar to Example 1. FIG. The polyimide composition 9 was not soluble. Moreover, since it was not soluble, the imidation ratio could not be measured. The results are shown in Table 1.

In addition, with respect to the compositions 1 to 3 obtained in Examples 1 to 3, the Vickers hardness and the elastic modulus were measured according to the method described above <Measurement of Vickers microhardness meter>. The results are shown in Table 2.

(Preparation of alignment film)
[Examples 8 to 14]
Using polyimide compositions 2 to 7 synthesized in Examples 2 to 7, alignment films 1 to 7 were produced as follows. Further, rubbing treatment was performed on each alignment film, and the presence or absence of scratches or scraping on the film after rubbing was confirmed with the naked eye.
The compositions 8 and 9 of Comparative Examples 1 and 2 were not soluble and the polyimide was deposited, so that the coating could not be performed and an alignment film could not be obtained.

(1) Preparation of alignment film Polyimide compositions 2 and 3 were diluted to 4% by mass with a coating solvent (N, N-dimethylacetamide) to obtain a coating solution. Polyimide compositions 4 to 7 use a coating solvent (N-methyl-2-pyrrolidone / anisole = 1/1), polyimide compositions 4 and 5 are 4% by mass, polyimide composition 6 is 10% by mass, The polyimide composition 7 was diluted to 3% by mass to prepare a coating solution. These coating solutions were respectively applied to glass substrates using a spin coater. Thereafter, the film was heated at 80 ° C. for 10 minutes and then heated at 140 ° C. for 1 hour to obtain alignment films 1 to 7.

(2) Rubbing treatment The prepared alignment films 1 to 7 were rubbed in one direction using a rayon cloth.
On the alignment films 1 to 7 subjected to the rubbing treatment, a composition for an anisotropic dye film was applied, and optical characteristics of the obtained anisotropic dye film were evaluated.

(3) Application of composition for anisotropic dye film 20 parts by mass of the azo compound represented by formula (I) and 1 part by mass of the compound represented by formula (II) are added to 79 parts by mass of water and stirred. After being dissolved, the solution was filtered to remove insoluble matter, thereby obtaining an aqueous dye solution (anisotropic dye film composition).

<Applicator application>
The above-mentioned anisotropic dye film composition is applied to the polyimide alignment film produced by the above method with an applicator (manufactured by Horita Seisakusho Co., Ltd.) with a gap of 4 μm, and then naturally dried to obtain an anisotropic dye film. It was.

<Die coat application>
The anisotropic dye film is formed by applying the above anisotropic dye film composition to the polyimide alignment film produced by the above method by applying it using a die coater having a slot width of 50 μm, and then naturally drying. Obtained.

(4) Optical performance The optical performance was evaluated by the single transmittance and the degree of polarization of the anisotropic dye film. The single transmittance and the degree of polarization were determined using a spectrophotometer equipped with a Gram-Thomson polarizer (product name “RETS-100” manufactured by Otsuka Electronics Co., Ltd.). The linearly polarized measuring light was incident on the anisotropic dye film and the transmittance was measured. Then, the degree of polarization at 620 nm, which is the maximum absorption wavelength of the anisotropic dye film, was calculated by the following equation.
Polarization degree (P) (%) = {(Ty−Tz) / (Ty + Tz)} ^1/2 × 100
Tz: Transmittance with respect to polarized light in the direction of the absorption axis of the anisotropic dye film Ty: Transmittance with respect to polarized light in the direction of the polarization axis of the anisotropic dye film Evaluation was performed as follows from the single transmittance and the degree of polarization.
A: Polarization degree of 99.5% or more when the single transmittance is 40% or more B: Single transmission is 36% or more and the polarization degree is 99% or more C: Single transmittance is 36% or more and the polarization degree is 95% or more, 99 Less than% D: Single transmittance is 36% or more and polarization degree is less than 95%

The evaluation of the alignment film is shown in Tables 3 and 4.

Examples 1 to 7 (polyimide compositions 1 to 7) were all soluble.
In addition, the alignment films 1 to 7 obtained by using the compositions 2 to 7 were free from scratches or scraping due to rubbing, and were shown to have excellent surface treatment resistance.
Further, since the alignment films 1 to 7 are excellent in the optical characteristics of the anisotropic dye film, it can be seen that the alignment films of the present invention have high alignment characteristics.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on October 7, 2013 (Japanese Patent Application No. 2013-210392) and a Japanese patent application filed on March 26, 2014 (Japanese Patent Application No. 2014-064536). Incorporated by reference.

The present invention can be used in any industrial field. For example, the present invention can be suitably used in a field where an alignment film having a high distribution characteristic is required. Specifically, for example, in the optical field, a display, etc. It can be particularly suitably used in a field where an optical element is required.

Claims

A polyimide composition used for an alignment film for anisotropic dye film,
The polyimide composition includes a polyimide and a solvent,
The said polyimide is represented by General formula (1), The polyimide composition characterized by the above-mentioned.

(In the general formula (1), X represents a tetravalent aliphatic hydrocarbon group having 5 or more carbon atoms,
R 1 represents a divalent organic group having an aromatic ring,
n represents an integer of 1 or more, and when n is 2 or more, a plurality of R 1 and X present in one molecule of the structure represented by the general formula (1) may be the same or different. Good. )
2. The polyimide composition according to claim 1, wherein a ratio of the number of elements forming an aromatic ring to the number of elements forming the main chain of the polyimide is 5% or more and 75% or less.
The polyimide composition according to claim 1 or 2, wherein the imidization ratio of the polyimide is 90% or more.
An alignment film for an anisotropic dye film, which is formed using the polyimide composition according to any one of claims 1 to 3.
An optical element comprising the alignment film for anisotropic dye film according to claim 4 and an anisotropic dye film laminated on the alignment film for anisotropic dye film.