CN115244105A - Polyimide varnish - Google Patents

Polyimide varnish Download PDF

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CN115244105A
CN115244105A CN202180020418.7A CN202180020418A CN115244105A CN 115244105 A CN115244105 A CN 115244105A CN 202180020418 A CN202180020418 A CN 202180020418A CN 115244105 A CN115244105 A CN 115244105A
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liquid crystal
polyimide
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丰田美希
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Nissan Chemical Corp
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1042Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/14Polyamide-imides
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1337Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1337Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133711Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
    • G02F1/133723Polyimide, polyamide-imide

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Abstract

The invention provides a polyimide varnish which can obtain a polyimide film with high film transmittance even if polyimide with a diphenylamine skeleton is used. The polyimide varnish of the present invention contains at least one block copolymer selected from the group consisting of a polyimide precursor having a block (b 1) containing a repeating unit represented by the following formula (1) and a block (b 2) containing a repeating unit represented by the following formula (2), and a polyimide obtained by imidizing the polyimide precursor. Formula (1) (X) 1 Represents a tetravalent organic group. X 2 Represents a tetravalent organic group derived from an acyclic aliphatic tetracarboxylic dianhydride or the following formula (X) 2 ) Tetravalent organic radicals shown. Y is 1 To representA divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton. Y is 2 Represents a divalent organic group having a diphenylamine skeleton. Two R 1 And R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, two Z' s 1 And Z 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, an alkenyl group having 2 to 10 carbon atoms which may be substituted, an alkynyl group having 2 to 10 carbon atoms which may be substituted, a tert-butoxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group. ) Formula (2) (R) 21 ~R 24 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group. )
Figure DDA0003840125520000011

Description

Polyimide varnish
Technical Field
The present invention relates to a polyimide varnish having a diphenylamine skeleton and capable of providing a polyimide film having a high film transmittance.
Background
Polyimide is widely used as a protective material in the electrical/electronic field because of its high mechanical strength, heat resistance, and solvent resistance, which are characteristics. Specifically, when the polyimide film is used as a liquid crystal alignment film for a liquid crystal display, a polyimide coating film having a thickness of 0.05 to 0.2 μm is usually formed on a transparent support substrate having a transparent electrode, and a thin polyimide coating film is usually formed on various support substrates.
In order to form a polyimide coating film, a polyimide varnish in which a polyimide (precursor) is dissolved in an appropriate organic solvent is usually applied to a support substrate by a method such as spin coating, offset printing, gravure printing, flexographic printing, or inkjet printing, and then subjected to a heat treatment.
In recent years, from the viewpoint of imparting various properties to a liquid crystal alignment film, polyimides having a diphenylamine skeleton have been proposed in patent documents 1 and 2.
Documents of the prior art
Patent document
Patent document 1: WO2004/021076 publication
Patent document 2: WO2013/008822
Disclosure of Invention
Problems to be solved by the invention
It has been clarified that the polyimide having a diphenylamine skeleton tends to lower the transmittance of the obtained film, and tends to affect the raw material monomer used in the polymerization reaction. As a result of studies, the present inventors have found that the transmittance of a film obtained from a polyimide obtained using a specific alicyclic tetracarboxylic dianhydride significantly decreases. As a result of examining various causes, it is found that when the polyimide (precursor) has a specific molecular arrangement, the film transmittance decreases. Further, it has been revealed that the structure of the imide precursor during the heat treatment is one of the main factors for inducing coloration.
In view of the above circumstances, an object of the present invention is to provide a polyimide varnish that can obtain a polyimide film having a high film transmittance even when a polyimide having a diphenylamine skeleton is used.
Means for solving the problems
The present inventors have conducted intensive studies in order to achieve the above-mentioned problems, and as a result, have found that a polyimide varnish containing a specific block copolymer is effective for achieving the above-mentioned object, and have completed the present invention.
The present invention is based on this finding, and the gist thereof is as follows.
A polyimide varnish containing at least one block copolymer selected from the group consisting of a polyimide precursor having a block (b 1) containing a repeating unit represented by the following formula (1) and a block (b 2) containing a repeating unit represented by the following formula (2), and a polyimide obtained by imidizing the polyimide precursor.
Figure BDA0003840125500000021
(X 1 Represents a tetravalent organic group. X 2 Represents a tetravalent organic group derived from an acyclic aliphatic tetracarboxylic dianhydride orA tetravalent organic group represented by the formula (X2). Y is 1 Represents a divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton. Y is 2 Represents a divalent organic group having a diphenylamine skeleton. Two R 1 And R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, two Z' s 1 And Z 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, an alkenyl group having 2 to 10 carbon atoms which may be substituted, an alkynyl group having 2 to 10 carbon atoms which may be substituted, a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. )
Figure BDA0003840125500000031
(R 21 ~R 24 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group. )
In the present specification, a "bond" means a bonding bond in any case. Boc represents tert-butoxycarbonyl. In the present specification, examples of the halogen atom include: fluorine atom, chlorine atom, bromine atom, iodine atom.
Effects of the invention
According to the polyimide varnish of the present invention, a polyimide film having high film transmittance can be obtained even when a polyimide having a diphenylamine skeleton is used. The polyimide varnish of the present invention can provide a polyimide film having a high film transmittance, and can also provide good polyimide film characteristics from other viewpoints (for example, voltage holding ratio, residual DC voltage, image retention characteristics, and scrub resistance). Further, the present invention provides a method for producing the polyimide varnish.
The mechanism by which the above-described effects are obtained in the present invention is not necessarily clear, and the following is considered to be one of the reasons.
That is, since the reaction of the diamine component having a diphenylamine skeleton with the acyclic aliphatic tetracarboxylic dianhydride or the specific alicyclic tetracarboxylic dianhydride component proceeds at a relatively low temperature, coloration due to oxidation of the diamine component in the reaction system can be suppressed as compared with a reaction at a high temperature. Further, since a film using a polyimide precursor obtained using a diamine having a diphenylamine skeleton and a non-cyclic aliphatic tetracarboxylic dianhydride or a specific alicyclic tetracarboxylic dianhydride is easily heat imidized during heat treatment, it is possible to reduce the electron donating property of the amine and to obtain a polyimide film having high film transmittance.
Drawings
FIG. 1 is a graph showing the transmittance obtained by using the liquid crystal aligning agent (A-1) of example 1 and the liquid crystal aligning agent (B-1) of comparative example 1.
Detailed Description
< Block copolymer >
The polyimide varnish of the present invention contains at least one block copolymer selected from the group consisting of a polyimide precursor having a block (b 1) containing a repeating unit represented by the following formula (1) and a block (b 2) containing a repeating unit represented by the following formula (2), and a polyimide obtained by imidizing the polyimide precursor. That is, the polyimide varnish of the present invention contains at least one block copolymer selected from the group consisting of a polyimide precursor having the block (b 1) and the block (b 2) and having no imide ring structure, and a polyimide having any of a repeating unit formed by imidizing the formula (1), a repeating unit formed by imidizing the formula (2), and a repeating unit formed by imidizing the other formula (2).
Figure BDA0003840125500000041
(X 1 Represents a tetravalent organic group. X 2 Represents a tetravalent organic group derived from a non-cyclic aliphatic tetracarboxylic dianhydride or a tetravalent organic group represented by the following formula (X2). Y is 1 Represents a divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton. Y is 2 To representA divalent organic group having a diphenylamine skeleton. Two R 1 And R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, two Z' s 1 And Z 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, an alkenyl group having 2 to 10 carbon atoms which may be substituted, an alkynyl group having 2 to 10 carbon atoms which may be substituted, a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. )
Figure BDA0003840125500000042
(R 21 ~R 24 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring. )
In the formula (1), X 1 Preferably a tetravalent organic group derived from a tetracarboxylic dianhydride, and more preferably at least one selected from the group consisting of structures represented by the following formulae (X1-1) to (X1-12).
Figure BDA0003840125500000051
In formula (1), Y 1 Preferably represents a divalent organic group having 3 to 50 carbon atoms having a structure represented by the following formulae (S1) to (S3) or a divalent organic group having 3 to 50 carbon atoms not having a structure represented by the formulae (S1) to (S3). The divalent organic group having 3 to 50 carbon atoms and having no structure represented by the formulas (S1) to (S3) and the divalent organic group having 3 to 50 carbon atoms and having no structure represented by the formulas (S1) to (S3) do not have a diphenylamine skeleton as described above. Specific examples of the divalent organic group having 3 to 50 carbon atoms, which does not have the structure represented by the formulae (S1) to (S3), include: divalent organic groups having a nitrogen-containing heterocycle in the molecule, such as the following formulas (2 a-1) to (2 a-14), divalent organic groups having a radical-initiating function, such as the following formulas (2 b-1) to (2 b-5), divalent organic groups having a carboxyl group, such as the following formulas (2 c-1) to (2 c-2), and the following formulas (2 d-1) to (2 d-1)A group having a group "-N (D) -" (D represents a t-butoxycarbonyl group) such as 2D-7), a group having photo-alignment properties such as the following formulas (2 e-1) to (2 e-11), a divalent organic group having an oxygen-containing heterocyclic ring such as the following formulas (2 f-1) to (2 f-3), or a divalent organic group derived from an aromatic diamine having no side chain group having 3 or more carbon atoms such as the following formulas (2-1) to (2-35).
Figure BDA0003840125500000052
(X 1 And X 2 Each independently represents a single bond, - (CH) 2 ) a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON (CH) 3 ) -, -NH-, -O-, -COO-, -OCO-or- ((CH) 2 ) a1 -A 1 ) m1 -. Wherein a1 is an integer of 1 to 15, respectively 1 Each independently represents an oxygen atom or-COO-, m 1 Is 1 to 2.G 1 And G 2 Each independently represents a divalent cyclic group selected from a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group is optionally substituted. m and n are each independently integers from 0 to 3, and m + n is from 1 to 4.R is 1 Represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms to form R 1 Optionally substituted with fluorine atoms. When m, n and ml are 2 or more, a plurality of X's are present 1 、X 2 、G 1 、G 2 A1, ml and A 1 Each independently having the above definitions. Examples of the substituent optionally substituted with any hydrogen atom on the cyclic group include a halogen atom, a halogen atom-containing alkyl group, a halogen atom-containing alkoxy group, a carbon 1-10 alkyl group, a carbon 1-10 alkoxy group, a carbon 2-10 alkenyl group, and a hetero atom-containing group in which any carbon-carbon bond of the halogen atom-containing alkyl group, halogen atom-containing alkoxy group, alkyl group, alkoxy group, and alkenyl group is interrupted by an oxygen atomAnd (4) a substituent. )
-X 3 -R 2 (S2)
(X 3 Represents a single bond, -CONH-, -NHCO-, -CON (CH) 3 )-、-NH-、-O-、-CH 2 O-, -COO-or-OCO-. R 2 Represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms to form R 2 Optionally substituted with fluorine atoms. )
-X 4 -R 3 (S3)
(X 4 represents-CONH-, -NHCO- ] -O-, -CH 2 O-, -COO-or-OCO-. R 3 Represents a structure having a steroid skeleton. )
Figure BDA0003840125500000071
Figure BDA0003840125500000081
Figure BDA0003840125500000091
Figure BDA0003840125500000101
From the viewpoint of improving the transmittance of the polyimide film obtained, Y in formula (1) 1 At least one of (a) and (b) is preferably a divalent organic group having a structure represented by the formulae (S1) to (S3), a divalent organic group having a nitrogen-containing heterocycle in the molecule, or a divalent organic group represented by the formulae (2-1) to (2-35). Specific examples of the divalent organic group having a structure represented by the above formulas (S1) to (S3) include groups obtained by removing two amino groups from diamines represented by the following formulas (Ys-1) to (Ys-13).
Figure BDA0003840125500000111
(wherein, in the formula, X v1 ~X v4 ,X p1 ~X p8 Each independently represents- (CH) 2 ) a - (a is an integer of 1 to 15), -CONH-, - -NHCO-, -CO-N (CH) 3 )-、-NH-、-O-、-CH 2 O-、-CH 2 -OCO-, -COO-or-OCO-, X v5 represents-O-, -CH 2 O-、-CH 2 -OCO-, -COO-or-OCO-, X V6 ~X V7 、X s1 ~X s4 Each independently represents-O-, -CH 2 O-, -COO-or-OCO-. X a ~X f Represents a single bond, -O-) -NH-, or-O- (CH) 2 ) m -O-,R v1 ~R v4 、R 1a ~R 1h Each independently represents-C n H 2n+1 (n is an integer of 1 to 20) or-O-C n H 2n+1 (n is an integer of 2 to 20). m represents an integer of 1 to 8. )
In the formula (1), two R 1 Each of which independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Two Z 1 Preferably each independently represents a hydrogen atom or a methyl group.
In the formula (1), X 1 、Y 1 、R 1 、Z 1 One or two or more kinds of the compounds may be used.
The block (b 1) having the repeating unit represented by the formula (1) may have any repeating unit other than the repeating unit represented by the formula (1).
The content of the repeating unit represented by the formula (1) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, and particularly preferably 20 to 70 mol% based on the total of the repeating units of the block (b 1) and the block (b 2).
In the formula (2), X 2 The "acyclic aliphatic tetracarboxylic dianhydride" of (1) is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. Among them, it is not necessary to constitute only a chain hydrocarbon structure, and a part thereof may have an alicyclic structure or an aromatic ring structure.
Specific examples of the "acyclic aliphatic tetracarboxylic dianhydride" include the following compounds (T) 2a )。
Figure BDA0003840125500000121
(X 2a Is selected from the following formulae (X) 2a -1)~(X 2a -5) at least one of the group consisting of the structures shown. )
Figure BDA0003840125500000122
In the formula (2), X 2 Preferably represents at least one selected from the group consisting of structures represented by the following formulae (X2-1) to (X2-4).
Figure BDA0003840125500000131
In formula (2), Y 2 Preferably, the structure represented by the following formula (d 2).
Figure BDA0003840125500000132
(A 1 Represents a single bond, -NR- (R represents a hydrogen atom or a monovalent organic group) -O-, -C (= O) -, or-C (= O) NR- (R represents a hydrogen atom or a monovalent organic group), -C (= O) O-or a divalent organic group. R 1 、R 2 Each independently represents a hydrogen atom or a monovalent organic group. When n is 2, a plurality of A's are present 1 And R 2 Each independently having the above definitions. )
As A 1 The divalent organic group in (1) includes: -CH 2 -、-C(CH 3 ) 2 An alkylene group having 2 to 20 carbon atoms; or a part of methylene groups of the alkylene group is substituted by-NR- (R represents a hydrogen atom or a monovalent organic groupA group), -O-, -C (= O) NR- (R represents a hydrogen atom or a monovalent organic group), or-C (= O) O-.
Examples of the monovalent organic group in the formula (d 2) include: alkyl groups having 1 to 10 carbon atoms such as methyl and ethyl; an alkyl group having 1 to 10 carbon atoms and having a halogen atom such as a trifluoroalkyl group; an alkoxyalkyl group having 1 to 10 carbon atoms; a group containing a thermally releasable group; or a part of methylene groups of the alkyl groups is replaced by-O-, -C (= O) -, or or-C (= O) NR- (wherein R represents a hydrogen atom or a methyl group) or a group substituted with a substituent (wherein, except for the group containing a thermally releasable group). Examples of the group containing a thermally releasable group include: a carbamate-based protective group such as a tert-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group, a 9-fluorenylmethoxycarbonyl group, or an allyloxycarbonyl group, or a group in which a part of a hydrogen atom in the alkyl group is substituted with a group "— O-E" (E represents a hydrogen atom or a carbamate-based protective group).
Is just Y 2 More preferable examples of the structure include the following formulas (d 2-1) to (d 2-13).
Figure BDA0003840125500000141
In the formula (2), two R 2 Each of which independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Two Z 2 Preferably each independently represents a hydrogen atom or a methyl group.
In the formula (2), X 2 、Y 2 、R 2 、Z 2 One or two or more kinds of the compounds may be used.
The block (b 2) having the repeating unit represented by the formula (2) may have any repeating unit other than the repeating unit represented by the formula (2).
The content of the repeating unit represented by the formula (2) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, and particularly preferably 20 to 70 mol% based on the total of the repeating units of the block (b 1) and the block (b 2).
The ratio of the total mole number of the repeating units represented by the formula (1) to the total mole number of the repeating units represented by the formula (2) per one molecule of the block copolymer of the present invention is preferably 9: 1 to 1: 9, more preferably 8: 2 to 2: 8, and particularly preferably 7: 3 to 3: 7.
When the ratio of the total mole number of the repeating units is within this range, the film is excellent in high transmittance.
The block copolymer of the present invention may have any repeating unit other than the block (b 1) containing the repeating unit represented by the formula (1) and the block (b 2) containing the repeating unit represented by the formula (2).
< production of polyimide precursor (Polyamic acid) >
Examples of the polyimide precursor used in the present invention include polyamic acid and polyamic acid ester.
The polyamic acid as a polyimide precursor used in the present invention can be produced, for example, by a production method including the following steps (I) to (II). A step (I) in which a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (1-T) or a derivative thereof is reacted with a diamine component comprising a diamine represented by the following formula (1-D) to obtain a block (b 1); and (II) a step of adding a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (2-T) or a derivative thereof and a diamine component comprising a diamine represented by the following formula (2-D) to the block (b 1) and reacting the resulting mixture to obtain a polyimide precursor comprising the block (b 1) and the block (b 2).
Figure BDA0003840125500000151
(X 1 、X 2 、Y 1 、Y 2 With X as defined in formula (1) and formula (2) 1 、X 2 、Y 1 、Y 2 The same is true. )
In the above, as the derivative of the tetracarboxylic dianhydride, there may be mentioned: tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid diester dichloride, tetracarboxylic acid diester, and the like.
The reaction temperature in the step (II) is preferably a temperature lower than the reaction temperature in the step (I), more preferably a temperature lower than the reaction temperature in the step (I) by at least 10 ℃, and particularly preferably a temperature lower than the reaction temperature in the step (I) by at least 20 ℃. The polyimide varnish containing the block copolymer obtained by the reaction in the above range does not require a high temperature during heating, and therefore oxidation during the reaction can be suppressed.
Preferably, the reaction temperature in the step (I) is 0 to 150 ℃ and the reaction temperature in the step (II) is-20 to 130 ℃. More preferably, the reaction temperature in the step (I) is 5 to 100 ℃ and the reaction temperature in the step (II) is-5 to 80 ℃.
The tetracarboxylic acid component in the step (I) may contain any tetracarboxylic acid dianhydride or derivative thereof other than the tetracarboxylic acid dianhydride represented by the above formula (1-T) or derivative thereof, but is preferably composed of the tetracarboxylic acid dianhydride represented by the above formula (1-T) or derivative thereof.
The diamine component in the step (I) may contain any diamine other than the diamine represented by the above formula (1-D), but is preferably composed of the diamine represented by the above formula (1-D).
The tetracarboxylic acid component in the step (II) may contain any tetracarboxylic acid dianhydride or derivative thereof other than the tetracarboxylic acid dianhydride represented by the above formula (2-T) or derivative thereof, but is preferably composed of the tetracarboxylic acid dianhydride represented by the above formula (2-T) or derivative thereof.
The diamine component in the step (II) may contain any diamine other than the diamine represented by the above formula (2-D), but is preferably composed of the diamine represented by the above formula (2-D).
The polyamic acid as the polyimide precursor used in the present invention can be produced by a production method including the following steps (III) to (V), for example.
A step (III) for obtaining a block (b 1) by reacting a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (1-T) or a derivative thereof with a diamine component comprising a diamine represented by the following formula (1-D); a step (IV) for reacting a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (2-T) or a derivative thereof with a diamine component comprising a diamine represented by the following formula (2-D) to obtain a block (b 2); and a step (V) of coupling the block (b 1) obtained in the step (III) with the block (b 2) obtained in the step (IV) to obtain a polyimide precursor comprising the block (b 1) and the block (b 2).
Figure BDA0003840125500000171
(X 1 、X 2 、Y 1 、Y 2 With X as defined in formula (1) and formula (2) 1 、X 2 、Y 1 、Y 2 The same is true. )
The reaction temperature in the step (IV) is preferably a temperature lower than the reaction temperature in the step (III), more preferably a temperature lower than the reaction temperature in the step (III) by at least 10 ℃, and particularly preferably a temperature lower than the reaction temperature in the step (III) by at least 20 ℃. The polyimide varnish containing the block copolymer obtained by the reaction in the above range does not require a high temperature during heating, and therefore oxidation during the reaction can be suppressed.
Preferably, the reaction temperature in the step (III) is 0 to 150 ℃ and the reaction temperature in the step (IV) is-20 to 130 ℃. More preferably, the reaction temperature in the step (III) is 5 to 100 ℃ and the reaction temperature in the step (IV) is-5 to 80 ℃.
The tetracarboxylic acid component in the step (III) may contain any tetracarboxylic acid dianhydride or derivative thereof other than the tetracarboxylic acid dianhydride represented by the formula (1-T) or derivative thereof, but is preferably composed of the tetracarboxylic acid dianhydride represented by the formula (1-T) or derivative thereof.
The diamine component in the step (III) may contain any diamine other than the diamine represented by the above formula (1-D), but is preferably composed of the diamine represented by the above formula (1-D).
The tetracarboxylic acid component in the step (IV) may contain any tetracarboxylic acid dianhydride or derivative thereof other than the tetracarboxylic acid dianhydride represented by the above formula (2-T) or derivative thereof, but is preferably composed of the tetracarboxylic acid dianhydride represented by the above formula (2-T) or derivative thereof.
The diamine component in the step (IV) may contain any diamine other than the diamine represented by the above formula (2-D), but is preferably composed of the diamine represented by the above formula (2-D).
The method for coupling the block (b 1) and the block (b 2) in the step (V) is not particularly limited, and examples thereof include: (1) A method in which, in the case where the terminal of the blocks (b 1) and (b 2) is an acid anhydride group or a derivative thereof, a diamine is added to further react; (2) A method in which a tetracarboxylic dianhydride or a derivative thereof is added to the block (b 1) or (b 2) in the case where the end is an amine end, and the reaction is further carried out; and (3) a method of reacting the block (b 1) with the block (b 2) in the case where the blocks (b 1) and (b 2) have both an arbitrary end of an acid anhydride group or a derivative thereof and an amine end.
The reaction of the diamine component with the tetracarboxylic acid component is usually carried out in an organic solvent. The organic solvent used in this case is not particularly limited as long as the polyimide precursor formed is dissolved therein. Specific examples of the organic solvent used in the reaction are given below, but the organic solvent is not limited to these examples. For example, there may be mentioned: n-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or gamma-butyrolactone, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, or 1,3-dimethyl-2-imidazolidinone.
When the polyimide precursor has high solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or an organic solvent represented by the following formulae [ D-1] to [ D-3] may be used.
Figure BDA0003840125500000181
Formula [ D-1]]In (D) 1 Represents an alkyl group having 1 to 3 carbon atoms, formula [ D-2]In (D) 2 Represents a carbon number of 1Alkyl of about 3, formula [ D-3]]In (D) 3 Represents an alkyl group having 1 to 4 carbon atoms.
These organic solvents may be used alone or in combination. Further, even if the solvent is a solvent that does not dissolve the polyimide precursor, the solvent may be used in a mixture with the polyimide precursor within a range where the polyimide precursor to be produced does not precipitate.
The concentration of the polyamic acid in the reaction system is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of a polymer is not likely to occur and a high molecular weight product is easily obtained.
The polyamic acid obtained as described above can be recovered by precipitating the polymer by pouring the reaction solution into a poor solvent while sufficiently stirring the solution. Further, the precipitation is performed several times, and after washing with a poor solvent, drying at normal temperature or under heating is performed, whereby a powder of the polyamic acid after purification can be obtained. The poor solvent is not particularly limited, and examples thereof include: water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene, and the like.
< production of polyimide precursor (polyamic acid ester) >
The polyamic acid ester as the polyimide precursor used in the present invention can be produced, for example, by the following reaction: (1) esterification reaction of polyamic acid using an esterifying agent; (2) reaction of a tetracarboxylic acid diester dichloride with a diamine; or (3) a polycondensation reaction of a tetracarboxylic acid diester with a diamine. The production method of the above (2) or (3) can be carried out in accordance with the production of the polyamic acid described above.
Among the three production methods, the production method of the above (1) or (2) is particularly preferable in order to obtain a high-molecular-weight polyamic acid ester.
The solution of the polyamic acid ester obtained as described above can be poured into a poor solvent while sufficiently stirring to precipitate a polymer. The polyamic acid ester is precipitated several times, washed with a poor solvent, and dried at room temperature or under heating to obtain a purified polyamic acid ester powder. The poor solvent is not particularly limited, and examples thereof include: water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene, and the like.
< production of polyimide >
The polyimide used in the present invention can be produced by imidizing the polyimide precursor.
In the polyimide used in the present invention, the ring-closing ratio of the amic acid group (also referred to as the imidization ratio) does not necessarily need to be 100%, and can be arbitrarily adjusted depending on the application and purpose.
For example, the imidization ratio of the polyimide may be 20% to 100%, 50% to 99%, or 70% to 99%, from the viewpoint of improving the solubility of the polyimide varnish.
The imidization may be performed by stirring the polyamic acid to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the organic solvent used in the polymerization reaction described above can be used. Examples of the basic catalyst include: pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferable because it has a suitable basicity for proceeding the reaction. Further, examples of the acid anhydride include: acetic anhydride, trimellitic anhydride, pyromellitic anhydride (pyroracemic anhydride), and the like, among them, acetic anhydride is preferable because purification after completion of the reaction becomes easy when acetic anhydride is used.
The temperature for the imidization is-20 to 140 ℃ and preferably 0 to 100 ℃ and the reaction time may be 0.5 to 100 hours and preferably 1 to 80 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times, the amount of the amic acid. The imidization ratio of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature, and the reaction time.
Since the catalyst and the like added remain in the solution after the imidization reaction of the polyimide precursor, it is preferable that the obtained imidized polymer is recovered by the following method, and redissolved in an organic solvent to be used as a component of the liquid crystal aligning agent of the present invention.
The solution of the polyimide obtained as described above can be poured into a poor solvent while sufficiently stirring to precipitate a polymer. The polyimide is precipitated several times, washed with a poor solvent, and dried at room temperature or under heating to obtain a purified polyimide powder.
The poor solvent is not particularly limited, and examples thereof include: methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and the like.
< polyimide varnish >
The polyimide varnish of the present invention contains the block copolymer. The content of the block copolymer in the polyimide varnish may be appropriately changed depending on the setting of the thickness of the polyimide film to be formed. From the viewpoint of forming a uniform and defect-free coating film, the amount of the liquid crystal aligning agent is preferably 1 to 10% by mass, more preferably 2 to 9% by mass, and particularly preferably 2 to 7% by mass of the entire liquid crystal aligning agent.
The polyimide varnish of the present invention preferably further contains at least one polymer (P) selected from the group consisting of a polyimide precursor having a repeating unit represented by the following formula (3) and a polyimide obtained by imidizing the polyimide precursor.
Figure BDA0003840125500000201
(X 3 Represents a tetravalent organic group, preferably a tetravalent organic group derived from a tetracarboxylic dianhydride. Y is 3 Represents a divalent organic group derived from a diamine, and preferably represents a divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton. R 3 、Z 3 And R of formula (1) 1 、Z 1 Synonymously. There are two R 3 And Z 3 Each independently having the above definitions. )
The polymer (P) preferably has no diphenylamine skeleton. By further containing the polymer (P), the characteristics of the polyimide varnish of the present invention (for example, the voltage holding ratio and the rubbing resistance of a liquid crystal alignment film obtained from the polyimide varnish) can be improved.
When the polyimide varnish of the present invention contains the polymer (P), the content ratio of at least one block copolymer (hereinafter, also referred to as block copolymer (b)) selected from the group consisting of a polyimide precursor having the block (b 1) and the block (b 2) and a polyimide obtained by imidizing the polyimide precursor to the polymer (P) may be 10/90 to 90/10, 20/80 to 90/10, or 20/80 to 80/20 in terms of the mass ratio of [ block copolymer (b) ]/[ polymer (P) ].
In formula (3), X 3 Preferably represents a compound selected from the following formulae (X3-1) to (X3-18) and the above formula (X) 2a -1)~(X 2a -2)、(X 2a -5) at least one of the group consisting of the structures shown. Preferable specific examples of the formula (X3-13) include those represented by the above formulae (X2-1) to (X2-4).
Figure BDA0003840125500000211
(R 31 ~R 34 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring. j and k represent 0 or 1,A 1 And A 2 Each independently represents a single bond, -O-, -CO-, or-COO-, phenylene, sulfonyl or amido. There are two A 2 Each independently having the above definitions. )
Preferable specific examples of (X3-17) and (X3-18) include the following formulas (X3-19) to (X3-34).
Figure BDA0003840125500000221
In formula (3), Y 3 Preferably represents a group selected from the group consisting of Y mentioned above 1 At least one of the group consisting of the structures shown.
In formula (3), two R 3 Each of which independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Two Z 3 Each of which independently represents a hydrogen atom or an alkyl group having 1 carbon atom is preferred.
In formula (3), X 3 、Y 3 、R 3 、Z 3 One or two or more kinds of the compounds may be used.
The polyimide precursor is preferably composed of the repeating unit represented by the formula (3).
The total of the repeating unit (3) and the imidized structural unit of the repeating unit (3) is more preferably 10 to 100 mol%, and still more preferably 15 to 100 mol% of the total repeating units in the polymer (P).
Wherein X in the above formula (3) 3 Are (X3-1) to (X3-11), (X3-13) (more preferably (X2-1) to (X2-4)), or (X 2a -1)~(X 2a The total of the repeating unit (3) of the — 2) and the imidized structural unit of the repeating unit (3) is more preferably 10 to 100 mol%, and still more preferably 15 to 100 mol%, based on the total of all the repeating units.
The polyimide varnish of the present invention further contains the polymer (P), whereby the following effects can be obtained: high voltage holding ratio and good orientation can be obtained.
The polyimide varnish of the present invention can be prepared, for example, by dispersing or dissolving the block copolymer of the present invention, and if necessary, the polymer (P) and other components in an organic solvent.
Examples of the other components include: antioxidants (phenol type, phosphite type, thioether type, etc.), ultraviolet absorbers, hindered amine type light stabilizers, nucleating agents, resin additives (fillers, talc, glass fibers, etc.), flame retardants, processability improvers/lubricants, and the like.
Examples of the organic solvent include: lactone solvents such as γ -valerolactone and γ -butyrolactone; lactam solvents such as γ -butyrolactam; amide solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-dimethylformamide, and N, N-dimethylacetamide; 4-hydroxy-4-methyl-2-pentanone, 2, 6-dimethyl-4-heptanone (diisobutyl ketone), methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol monomethyl ether, ethylene glycol ethyl ether, ethylene glycol monobutyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monobutyl ether, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, isoamyl propionate, diisoamyl isobutyrate, diisoamyl ether; carbonate solvents such as ethylene carbonate and propylene carbonate; 1-hexanol, cyclohexanol, 1,2-ethanediol, diisobutylcarbinol (2,6-dimethyl-4-heptanol), and the like. These may be used alone or in combination of two or more.
Preferred combinations of solvents include: n-methyl-2-pyrrolidone with ethylene glycol monobutyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, and ethylene glycol monobutyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, and propylene glycol monobutyl ether; n-ethyl-2-pyrrolidone with propylene glycol monobutyl ether; n-methyl-2-pyrrolidone, γ -butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether; n-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate; gamma-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone; gamma-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and diisobutyl ketone; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol; n-methyl-2-pyrrolidone, gamma-butyrolactone, and dipropylene glycol dimethyl ether; n-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, and the like. The kind and content of such a solvent can be appropriately selected depending on the coating apparatus, coating conditions, coating environment, and the like of the liquid crystal aligning agent.
< liquid Crystal Aligning agent >
The liquid crystal aligning agent of the present invention is preferably prepared as a coating liquid in a manner suitable for forming a liquid crystal alignment film. The liquid crystal aligning agent of the present invention can be prepared by, for example, dispersing or dissolving the polyimide varnish of the present invention and other components as required in an organic solvent.
Examples of the other components include: a crosslinkable compound, a functional silane compound, a surfactant, a compound having a photopolymerizable group, an organic solvent, and the like.
The crosslinkable compound can be used for the purpose of improving the strength of the liquid crystal alignment film. Examples of the crosslinkable compound include: examples of the compound having an isocyanate group or a cyclocarbonate group, the compound having at least one group selected from the group consisting of lower alkoxyalkyl groups, and the compound having a blocked isocyanate group are disclosed in paragraphs [0109] to [0113] of International patent application laid-open No. WO 2016/047771.
The blocked isocyanate compound is commercially available, and examples thereof include CORONATE AP STABLE M, CORONATE 2503, 2515, 2507, 2513, 2555, MILLIONATE MS-50 (manufactured by NIPPON POLYURETHANE INDUSTRIAL CO., LTD.), TAKENATE B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (manufactured by Mitsui Chemicals Co., ltd.).
Specific examples of preferable crosslinkable compounds include compounds represented by the following formulas (CL-1) to (CL-11).
Figure BDA0003840125500000251
The above is an example of the crosslinkable compound, and is not limited thereto. The liquid crystal aligning agent of the present invention may be used in combination with one or more kinds of crosslinkable compounds.
The content of the other crosslinkable compound in the liquid crystal aligning agent of the present invention is 0.1 to 150 parts by mass, or 0.1 to 100 parts by mass, or 1 to 50 parts by mass based on 100 parts by mass of the total polymer components.
The functional silane compound can be used for the purpose of improving the adhesion between the liquid crystal alignment film and the base substrate. Specific examples thereof include silane compounds described in paragraph [0019] of International publication No. 2014/119682. The content of the functional silane compound is preferably 0.1 to 30 parts by mass, and more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the entire polymer component.
The surfactant can be used for the purpose of improving the uniformity of the film thickness and the surface smoothness of the liquid crystal alignment film. Examples of the compound include: fluorine-based surfactants, silicone-based surfactants, nonionic surfactants, and the like. Specific examples thereof include the surfactants described in paragraph [0117] of International publication WO 2016/047771. The amount of the surfactant to be used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, based on 100 parts by mass of the total polymer components contained in the liquid crystal aligning agent.
Examples of the compound having a photopolymerizable group include compounds having one or more polymerizable unsaturated groups such as an acrylate group and a methacrylate group in the molecule, and examples thereof include compounds represented by the following formulae (M-1) to (M-7).
Figure BDA0003840125500000261
Further, as a compound which promotes charge transfer in the liquid crystal alignment film and promotes charge elution of the element, a nitrogen-containing heterocyclic amine compound represented by the formulae [ M1] to [ M156] described in paragraphs [0194] to [0200] of International publication No. WO2011/132751 (published by 2011.10.27), and more preferably 3-aminomethylpyridine or 4-aminomethylpyridine, can be added to the liquid crystal alignment agent of the present invention. The amine compound may be added directly to the liquid crystal aligning agent, but is preferably added after being prepared into a solution having a concentration of 0.1 to 10% by mass, preferably 1 to 7% by mass. The solvent is not particularly limited as long as the polyimide varnish is dissolved.
When the liquid crystal aligning agent of the present invention contains polyamic acid, polyamic acid ester, or polyamic acid-polyamic acid ester copolymer, an imidization accelerator or the like may be added for the purpose of efficiently performing imidization by heating when a coating film is baked.
Examples of the organic solvent contained in the liquid crystal aligning agent of the present invention include: lactone solvents such as γ -valerolactone and γ -butyrolactone; lactam solvents such as γ -butyrolactam, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone; amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; 4-hydroxy-4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol monomethyl ether, ethylene glycol ethyl ether, ethylene glycol monobutyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monobutyl ether, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, isoamyl propionate, isoamyl isobutyrate, diisopropyl ether, diisoamyl ether; carbonate solvents such as ethylene carbonate and propylene carbonate; 1-hexanol, cyclohexanol, 1, 2-ethanediol, 2,6-dimethyl-4-heptanol, and the like. These may be used alone or in combination of two or more.
Preferred combinations of solvents include: n-methyl-2-pyrrolidone with ethylene glycol monobutyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, and ethylene glycol monobutyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, and propylene glycol monobutyl ether; n-ethyl-2-pyrrolidone with propylene glycol monobutyl ether; n-methyl-2-pyrrolidone, γ -butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether; n-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and 2,6-dimethyl-4-heptanone; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether; n-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate; gamma-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and 2,6-dimethyl-4-heptanone; gamma-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and 2,6-dimethyl-4-heptanone; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and 2,6-dimethyl-4-heptanol; n-methyl-2-pyrrolidone, gamma-butyrolactone, and dipropylene glycol dimethyl ether; n-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, and the like. The kind and content of such a solvent are appropriately selected depending on the coating apparatus, coating conditions, coating environment, and the like of the liquid crystal aligning agent.
The concentration of the solid component in the liquid crystal aligning agent (the ratio of the total mass of the components other than the organic solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, and the like, and is preferably in the range of 1 to 10 mass%.
The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spin coating method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5 mass%. When the printing method is used, it is particularly preferable that the solution viscosity is set to a range of 12 to 50mPa · s by setting the solid content concentration to a range of 3 to 9 mass%. In the case of using the ink jet method, it is particularly preferable to set the solid content concentration to a range of 1 to 5 mass% and thereby set the solution viscosity to a range of 3 to 15mPa · s.
< liquid crystal alignment film/liquid crystal display element >
The liquid crystal alignment film of the present invention is obtained from the liquid crystal aligning agent. The liquid crystal alignment film of the present invention can be used for a liquid crystal alignment film of a horizontal alignment type or a vertical alignment type. The liquid crystal Alignment film of the Vertical Alignment type is suitable for a liquid crystal display element of the Vertical Alignment type such as a VA (Vertical Alignment) mode or a PSA (Polymer stabilized Alignment) mode. More preferably, the vertical alignment type liquid crystal alignment film is preferably used for a liquid crystal display element obtained by a method for manufacturing a liquid crystal display element in which a pair of substrates having conductive films are coated to form coating films, the coating films are arranged to face each other with a layer of liquid crystal molecules interposed therebetween to form a liquid crystal cell, and the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates. More specifically, the liquid crystal display device is a PSA type liquid crystal display device or an SC-PVA (Patterned Vertical Alignment) mode liquid crystal display device, which will be described later. The liquid crystal display element of the present invention includes the liquid crystal alignment film. The liquid crystal display element of the present invention can be manufactured by a method including the following steps (1) to (3) or steps (1) to (4), for example.
(1) Coating liquid crystal aligning agent on substrate
The liquid crystal aligning agent of the present invention is applied to one surface of a substrate provided with a patterned transparent conductive film by an appropriate application method such as a roll coater method, a spin coating method, a printing method, an inkjet method, or the like. Here, the substrate is not particularly limited as long as it is a highly transparent substrate, and a plastic substrate such as an acrylic substrate or a polycarbonate substrate may be used together with a glass substrate or a silicon nitride substrate. In the reflective liquid crystal display element, an opaque material such as a silicon wafer may be used as the single-sided substrate, and in this case, a material that reflects light such as aluminum may be used as the electrode.
(2) Firing the coating film
After the liquid crystal aligning agent is applied, it is preferable to first perform preliminary heating (prebaking) for the purpose of preventing the liquid of the applied aligning agent from sagging. The prebaking temperature is preferably from 30 to 200 ℃, more preferably from 40 to 150 ℃, and particularly preferably from 40 to 100 ℃. The prebaking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. And preferably a heating (post-baking) process is performed.
The post-baking temperature is preferably 80 to 300 deg.C, more preferably 120 to 250 deg.C. The postbaking time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the film thus formed is preferably 5 to 300nm, more preferably 10 to 200nm.
The coating film formed in the step (1) may be used as a liquid crystal alignment film as it is, or may be subjected to a treatment for imparting alignment ability. Examples of the treatment for imparting orientation ability include: for example, a brush-polishing treatment in which a coating film is rubbed in a certain direction by a roll formed by winding a fabric made of a fiber such as nylon, rayon, or cotton; and photo-alignment treatment in which the coating film is irradiated with polarized or unpolarized radiation.
In the photo-alignment treatment, as the radiation to be irradiated to the coating film, for example, ultraviolet rays and visible rays including light having a wavelength of 150 to 800nm can be used. In the case of radiation polarization, it may be linear polarization or partial polarization. When the radiation to be used is linearly polarized or partially polarized, the irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination thereof. When unpolarized radiation is irradiated, the irradiation direction is an oblique direction.
(3) Step of Forming liquid Crystal layer
(3-1) case of VA type liquid Crystal display element
As described above, two substrates on which liquid crystal alignment films are formed are prepared, and liquid crystal is disposed between the two substrates disposed to face each other. Specifically, the following two methods can be exemplified. The first method is a conventionally known method. First, two substrates are arranged to face each other with a gap (cell gap) therebetween so that the liquid crystal alignment films face each other. Next, peripheral portions of the two substrates were bonded to each other with a sealant, and a liquid crystal composition was filled into a cell gap defined by the surfaces of the substrates and the sealant, and the filling hole was sealed after contacting the film surface.
The second method is a method called an ODF (One Drop Fill) method. For example, a uv-curable sealant is applied to a predetermined position on one of the two substrates on which the liquid crystal alignment film is formed, and the liquid crystal composition is further dropped onto predetermined several places on the surface of the liquid crystal alignment film. Then, the other substrate was bonded so that the liquid crystal alignment films were opposed to each other, and the liquid crystal composition was spread over the entire surface of the substrate and brought into contact with the film surface. Subsequently, the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant. In either method, it is desirable that the liquid crystal composition to be used is further heated to a temperature at which the liquid crystal composition becomes in the same phase, and then gradually cooled to room temperature, thereby removing the flow alignment at the time of filling the liquid crystal.
(3-2) case of manufacturing PSA type liquid Crystal display device
The same as in (3-1) above, except that the liquid crystal composition containing the polymerizable compound is injected or dropped. Examples of the polymerizable compound include polymerizable compounds represented by the above-mentioned formulas (M-1) to (M-7).
(3-3) when a coating film is formed on a substrate using a liquid crystal aligning agent containing a compound having a polymerizable group
After the same procedure as in (3-1) above, a method of manufacturing a liquid crystal display element through a step of irradiating ultraviolet rays described later may be employed. According to this method, a liquid crystal display element having excellent response speed can be obtained with a small amount of light irradiation, as in the case of manufacturing the PSA-type liquid crystal display element. The compound having a polymerizable group may be a compound having one or more polymerizable unsaturated groups such as an acrylate group and a methacrylate group in the molecule, as represented by the above-mentioned formulae (M-1) to (M-7), and the content thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, based on 100 parts by mass of the entire polymer component. The polymerizable group may have a polymer used for a liquid crystal aligning agent, and examples of such a polymer include a polymer obtained by using a diamine component containing a diamine having the photopolymerizable group at a terminal thereof for a reaction.
(4) Step of irradiating ultraviolet ray
In a state where a voltage is applied between the conductive films provided on the pair of substrates obtained in the above (3-2) or (3-3), light irradiation is performed on the liquid crystal cell. Here, the applied voltage may be, for example, a direct current or an alternating current of 5 to 50V. The light to be irradiated may be, for example, ultraviolet light and visible light including light having a wavelength of 150 to 800nm, and preferably ultraviolet light including light having a wavelength of 300 to 400 nm. As a light source for irradiating light, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, or the like can be used. The dose of light irradiation is preferably 1000 to 200000J/m 2 More preferably 1000 to 100000J/m 2
Further, a polarizing plate may be bonded to the outer surface of the liquid crystal cell to obtain a liquid crystal display element. Examples of the polarizing plate bonded to the outer surface of the liquid crystal cell include: a polarizing plate which is formed by sandwiching a polarizing film called an "H film" which absorbs iodine while extending and orienting polyvinyl alcohol with a cellulose acetate protective film; or a polarizing plate composed of the H film itself.
The liquid crystal display element of the present invention can be effectively used for various devices, for example, various display devices such as a timepiece, a portable game machine, a word processor (word processor), a notebook computer, a car navigation system, a camcorder (camcorder), a PDA (Personal Digital Assistant), a Digital camera, a mobile phone, a smart phone, various monitors, a liquid crystal television, an information display, and the like.
Examples
The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples at all.
< Synthesis of liquid Crystal alignment agent >
The abbreviations used in the preparation of the liquid crystal aligning agents described below are as follows.
(tetracarboxylic dianhydride)
BODA: bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride.
CBDA:1,2,3,4-cyclobutanetetracarboxylic dianhydride.
BDA: meso-butane-1,2,3,4-tetracarboxylic dianhydride.
(diamine)
Figure BDA0003840125500000321
(additives)
Figure BDA0003840125500000322
(solvent)
NMP: n-methyl-2-pyrrolidone, BCS: butyl cellosolve.
< determination of molecular weight >
A measuring device: normal temperature Gel Permeation Chromatography (GPC) (SSC-7200) manufactured by SENSHU scientific Co., ltd.; a chromatographic column: column chromatography (KD-803, KD-805 in series) made by Shodex; temperature of the column: 50 ℃; eluent: n, N-dimethylformamide (as additive, lithium bromide monohydrate)Compound (LiBr. H) 2 O) 30mmol/L, phosphoric acid/anhydrous crystals (O-phosphoric acid) 30mmol/L, tetrahydrofuran (THF) 10 ml/L); flow rate: 1.0 mL/min; calibration curve preparation standard sample: TSK-standard polyethylene oxides (molecular weights of about 900000, 150000, 100000, 30000, manufactured by Tosoh corporation) and polyethylene glycols (molecular weights of about 12000, 4000, 1000, manufactured by Polymer Laboratory corporation).
< measurement of imidization Rate >
To an NMR sample tube (NMR Standard tube. Phi.5 manufactured by Softgrass scientific Co., ltd.), 20mg of polyimide powder was added, and deuterated dimethyl sulfoxide (DMSO-d) was added 6 0.05%) of the tms mixed product) 1.0mL, and ultrasonic waves were applied thereto to completely dissolve the tms mixed product. The proton NMR of the solution at 500MHz was measured by using an NMR measuring instrument (JNW-ECA 500) manufactured by electronic DATUM of Japan.
The chemical imidization ratio was determined in the following manner: the proton derived from a structure which does not change before and after imidization is determined as a reference proton, and the peak integral value of the proton derived from the amic acid-derived NH group appearing in the vicinity of 9.5 to 10.0ppm are used to obtain the following formula. In the formula, x is a peak integrated value of a proton derived from an NH group of amic acid, y is a peak integrated value of a reference proton, and α is a ratio of the number of reference protons to the number of protons of one NH group of amic acid in the case of polyamic acid (imidization ratio of 0%).
Imidization ratio (%) = (1-. Alpha.x/y). Times.100
< Synthesis example 1 >
BODA (1.75g, 7.0mmol) and DA-5 (1.66g, 8.4mmol) were dissolved in NMP (13.7 g), reacted at 60 ℃ for 3 hours, then DA-1 (1.12g, 5.6mmol) and NMP (4.5 g) were added thereto and dissolved, CBDA (1.31g, 6.7mmol) and NMP (5.3 g) were added thereto and reacted at 40 ℃ for 4 hours, and a polyamic acid solution (1) was obtained. The polyamic acid had a number average molecular weight Mn of 10200 and a weight average molecular weight Mw of 38400.
< Synthesis example 2 >
BODA (1.88g, 7.5 mmol), DA-3 (0.65g, 6.0 mmol) and DA-4 (1.18g, 3.0 mmol) were dissolved in NMP (14.8 g), and after reaction at 60 ℃ for 3 hours, DA-1 (1.20g, 6.0 mmol) and NMP (4.8 g) were added and dissolved, CBDA (1.41g, 7.2mmol) and NMP (5.6 g) were added, and reaction at 40 ℃ for 4 hours gave a polyamic acid solution (2). The polyamic acid had Mn of 11200 and Mw of 25800.
< Synthesis example 3 >
BODA (0.75g, 3.0 mmol) and DA-5 (2.08g, 10.5 mmol) were dissolved in NMP (11.3 g), reacted at 60 ℃ for 3 hours, DA-2 (0.96g, 4.5 mmol) and NMP (3.8 g) were added and dissolved, CBDA (2.18g, 11.1mmol) and NMP (8.7 g) were added, and reacted at 40 ℃ for 4 hours to obtain a polyamic acid solution (3). The polyamic acid had an Mn of 10600 and an Mw of 28700.
< Synthesis example 4 >
BODA (2.50g, 10.0mmol), DA-5 (0.99g, 5.0mmol), DA-6 (0.66g, 2.0mmol), DA-7 (1.42g, 6.0mmol) and DA-4 (2.76g, 7.0mmol) were dissolved in NMP (33.4 g), and after reaction at 60 ℃ for 3 hours, CBDA (1.92g, 9.8mmol) and NMP (7.7 g) were added to react at 40 ℃ for 4 hours, thereby obtaining a polyamic acid solution. To the polyamic acid solution (25 g) was added NMP to dilute the solution to 6.5 mass%, and then acetic anhydride (4.96 g) and pyridine (1.53 g) were added as imidization catalysts to react at 50 ℃ for 3 hours. The reaction solution was poured into methanol (334 g), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 60 ℃ to obtain polyimide powder. The polyimide had an imidization ratio of 59%, mn of 12500 and Mw of 42300. To the obtained polyimide powder (2.0 g), NMP (28.0 g) was added and the mixture was stirred at 70 ℃ for 15 hours to dissolve the powder. BCS (20.0 g) was added to the solution to obtain a polyimide solution (1).
< Synthesis example 5 >
BDA (2.58g, 13.0mmol), DA-8 (3.42g, 14.0mmol) and DA-9 (3.34g, 6.0mmol) were dissolved in NMP (52.9 g), and reacted at 50 ℃ for 2 hours, then CBDA (1.33g, 6.8mmol) and NMP (7.6 g) were added, and reacted at 40 ℃ for 4 hours to obtain a polyamic acid solution. To the polyamic acid solution (25 g) was added NMP to dilute the solution to 6.5 mass%, and then acetic anhydride (3.59 g) and pyridine (1.11 g) were added as imidization catalysts to react at 40 ℃ for 2.5 hours. The reaction solution was poured into methanol (250 g), and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 60 ℃ to obtain polyimide powder. The polyimide had an imidization ratio of 65%, mn of 11200 and Mw of 38100. NMP (28.0 g) was added to the obtained polyimide powder (2.0 g), and the mixture was stirred at 70 ℃ for 15 hours to dissolve the polyimide powder. BCS (20.0 g) was added to the solution to obtain a polyimide solution (2).
Comparative Synthesis example 1
BODA (1.75g, 7.0mmol), DA-5 (1.66g, 8.4mmol) and DA-1 (1.12g, 5.6mmol) were dissolved in NMP (18.1 g), and after reaction at 60 ℃ for 3 hours, CBDA (1.31g, 6.7mmol) and NMP (5.2 g) were added, and reaction at 40 ℃ for 4 hours gave a polyamic acid solution (4). The polyamic acid had an Mn of 11100 and an Mw of 31900.
Comparative Synthesis example 2
BODA (1.88g, 7.5 mmol), DA-3 (0.65g, 6.0mmol), DA-4 (1.18g, 3.0mmol) and DA-1 (1.20g, 6.0mmol) were dissolved in NMP (19.6 g), and after reaction at 60 ℃ for 3 hours, CBDA (1.41g, 7.2mmol) and NMP (5.5 g) were added to react at 40 ℃ for 4 hours, thereby obtaining a polyamic acid solution (5). The polyamic acid had Mn of 10000 and Mw of 20200.
Comparative Synthesis example 3
BODA (0.75g, 3.0mmol), DA-5 (2.08g, 10.5mmol) and DA-2 (0.96g, 4.5mmol) were dissolved in NMP (15.2 g), and after reaction at 60 ℃ for 3 hours, CBDA (2.18g, 11.1mmol) and NMP (8.7 g) were added and reaction at 40 ℃ for 4 hours gave a polyamic acid solution (6). The polyamic acid had Mn of 9400 and Mw of 34200.
The specifications of the polymers obtained in the above synthesis examples and comparative synthesis examples are shown in table 1 below.
[ Table 1]
Figure BDA0003840125500000351
< preparation of liquid Crystal Aligning agent >
Examples of the preparation of the liquid crystal aligning agent are described in examples and comparative examples. The liquid crystal aligning agents obtained in examples and comparative examples were used to fabricate liquid crystal display elements and to perform various evaluations.
[ example 1]
NMP (16.0 g) and BCS (16.0 g) were added to polyamic acid solution (1) (8.0 g) obtained in Synthesis example 1, and stirred at room temperature for 2 hours, thereby obtaining liquid crystal aligning agent (A-1).
Examples 2 and 3 and comparative examples 1 to 3
Liquid crystal alignment agents (A-2), (A-3), and (B-1) to (B-3) of examples 2 and 3 and comparative examples 1 to 3 were obtained in the same manner as in example 1, except that the polyamic acid solutions (2) to (6) were used instead of the polyamic acid solution (1).
[ example 4]
A liquid crystal aligning agent (C-1) was obtained by mixing the polyimide solution (1) (3.0 g) obtained in Synthesis example 4, the liquid crystal aligning agent (A-1) (7.0 g) obtained in example 1, and AD-1 (0.04 g).
Examples 5 and 6 and comparative examples 4 to 6
Liquid crystal aligning agents (C-2), (C-3), (D-1) to (D-3) of examples 5 and 6 and comparative examples 4 to 6 were obtained in the same manner as in example 4 except that liquid crystal aligning agents (A-2), (A-3), (B-1) to (B-3) were used instead of liquid crystal aligning agent (A-1).
[ example 7]
The polyimide solution (2) (3.0 g) obtained in Synthesis example 5 and the liquid crystal aligning agent (A-1) (7.0 g) obtained in example 1 were mixed to obtain a liquid crystal aligning agent (C-4).
Example 8 and comparative examples 7 and 8
Liquid crystal aligning agents (C-5), (D-4) and (D-5) of example 8 and comparative examples 7 and 8 were obtained in the same manner as in example 7 except that the liquid crystal aligning agents (A-3), (B-1) and (B-3) were used in place of the liquid crystal aligning agent (A-1).
The liquid crystal aligning agents (A-1) to (A-3), (B-1) to (B-3), (C-1) to (C-5), and (D-1) to (D-5) obtained as described above were not observed to have abnormalities such as cloudiness and precipitation, and were confirmed to be homogeneous solutions. The obtained liquid crystal alignment agent was used to evaluate transmittance, manufacture a liquid crystal cell, evaluate a voltage holding ratio, and evaluate a residual DC voltage.
[ evaluation of transmittance ]
The liquid crystal alignment agents (A-1) to (A-3), (C-1) to (C-5), (B-1) to (B-3), and (D-1) to (D-5) obtained in examples and comparative examples were spin-coated on a quartz substrate, and dried on a hot plate at 70 ℃ for 90 seconds. Then, the resultant was baked in an IR (infrared) oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100nm, thereby obtaining a substrate with a liquid crystal alignment film. The substrate with the liquid crystal alignment film was set inside, and a refractive liquid (contact liquid manufactured by shimadzu instruments) was sandwiched between two quartz substrates for the purpose of preventing light interference. For the evaluation of the transmittance, the measurement was carried out at a scanning wavelength of 380 to 800nm at a temperature of 25 ℃ using a UV-3600 (manufactured by Shimadzu corporation). In this case, the reference uses two uncoated quartz substrates sandwiching a refractive liquid. The transmittance at a wavelength of 580nm was used as a reference, and the values are shown in table 2 below, and an example of the relationship between the wavelength and the transmittance is shown in fig. 1.
[ production of liquid Crystal display device for evaluation of Voltage holding ratio and residual DC characteristics ]
Liquid crystal cells were produced in the order described below using the liquid crystal aligning agents (A-1) to (A-3), (C-1) to (C-3), (B-1) to (B-3), and (D-1) to (D-3) obtained in examples and comparative examples. The liquid crystal alignment agent was spin-coated on a glass substrate having an ITO electrode, dried on a hot plate at 70 ℃ for 90 seconds, and then fired in an IR oven at 230 ℃ for 20 minutes to form a liquid crystal alignment film having a film thickness of 100 nm. Two substrates with the liquid crystal alignment films were prepared, and a bead spacer (Nissan catalyst chemical Co., ltd., fizeau ball, SW-D1) having a diameter of 4 μm was coated on one of the liquid crystal alignment films, and a thermosetting sealing agent (XN-1500T, manufactured by Mitsui chemical Co., ltd.) was printed thereon. Next, the other substrate was bonded to the former substrate with the surface on which the liquid crystal alignment film was formed being the inner side, and then the sealant was cured to produce an empty cell. Liquid crystal MLC-3023 (manufactured by MERCK) was injected into the empty cell by vacuum injection to produce a liquid crystalAnd (5) a box. Then, the cell was irradiated with a DC voltage of 15V from the outside thereof to 10J/cm 2 UV passing through a cut-off filter of 325nm or less. The UV illuminance was measured by using UV-MO3A manufactured by ORC. Then, toshiba Lighting was used in a state where no voltage was applied for the purpose of inactivating the unreacted polymerizable compound remaining in the liquid crystal cell&A UV-FL irradiation apparatus manufactured by the company Technology irradiates UV for 30 minutes (UV lamp: FLR40SUV 32/A-1).
[ production of liquid Crystal display device for evaluating residual image characteristics ]
Using the liquid crystal aligning agents (A-2), (C-1) to (C-3), (B-2), and (D-1) to (D-3) obtained in examples and comparative examples, liquid crystal cells were produced in the following order. Liquid crystal aligning agents were spin-coated on the ITO surface of an ITO electrode substrate (length: 35mm, width: 30mm, thickness: 0.7 mm) on which an ITO electrode pattern having a pixel size of 200. Mu. M.times.600. Mu.m and a line width/line pitch (line/space) of 3 μm was formed, and a glass substrate (length: 35mm, width: 30mm, thickness: 0.7 mm) with an ITO electrode on which an optical spacer (photo spacer) having a height of 3.2 μm was patterned, and after drying at 70 ℃ for 90 seconds on a hot plate, firing was carried out in an IR type oven at 230 ℃ for 20 minutes to form a liquid crystal alignment film having a film thickness of 100 nm. The ITO electrode substrate on which the ITO electrode pattern is formed is divided into four cross-grid (checkered) patterns, and can be driven for each of the four regions.
Next, a sealing agent (XN-1500T, manufactured by Mitsui chemical Co., ltd.) was printed. Next, the other substrate was bonded to the former substrate with the surface on which the liquid crystal alignment film was formed being the inner side, and then the sealant was cured to produce an empty cell. The empty cell was filled with liquid crystal MLC-3023 (manufactured by MERCK) by a reduced pressure injection method to fabricate a liquid crystal cell. Irradiating the liquid crystal cell with a DC voltage of 15V from the outside to 10J/cm 2 UV passing through a cut-off filter of 325nm or less. The illuminance of UV was measured by using UV-MO3A manufactured by ORC. Then, the unreacted polymerizable compound remaining in the liquid crystal cell is deactivatedIn the state of no voltage application, toshiba Lighting is used&UV-FL irradiation apparatus manufactured by Technology corporation irradiated for 30 minutes UV (UV lamp: FLR40SUV 32/A-1).
[ evaluation of Voltage holding ratio ]
The voltage holding ratio was measured using a liquid crystal cell for evaluation of voltage holding ratio after UV irradiation. A voltage of 1V was applied for 60. Mu.s in a hot air circulating oven at 60 ℃, and then the voltage after 16.67msec was measured, and how much the voltage could be held was calculated as a voltage holding ratio. VHR-1 manufactured by TOYO Corporation was used for the measurement of the voltage holding ratio. The values are shown in table 2 below.
[ evaluation of residual DC Voltage ]
The rectangular wave of 30Hz and 7.8Vpp superimposed with DC 2V was applied to the cell for voltage holding ratio evaluation prepared above at 25 ℃ for 100 hours, and the voltage remaining in the cell (residual DC voltage) after the DC voltage was cut off for 1 hour was determined by a flicker elimination method. The values are shown in table 2 below.
[ afterimage characteristics ]
Using the liquid crystal cell for evaluation of afterimage characteristics prepared in the above, an alternating voltage of 60Hz and 20Vp-p was applied to two regions of the diagonal line of the four pixel regions, and the cell was driven at 25 ℃ for 168 hours. Then, all four pixel regions were driven with an alternating voltage of 5Vp-p, and the luminance difference of the pixels was visually observed. The evaluation results are shown in table 2, assuming that the state in which the luminance difference was hardly observed was good.
[ scrub resistance ]
The liquid crystal aligning agents (C-4), (C-5), (B-1), (B-3), (D-4) and (D-5) obtained in examples and comparative examples were spin-coated on the ITO surface of a glass substrate having an ITO electrode on the entire surface, and were provisionally dried on a hot plate at 70 ℃ for 90 seconds. Then, the resultant was baked in an IR oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100nm, thereby obtaining a substrate with a liquid crystal alignment film. The liquid crystal alignment film was brushed with rayon cloth (roll diameter: 120mm, roll rotation speed: 1000rpm, moving speed: 20mm/sec, pressing length: 0.6 mm). When the substrate was observed with a microscope, the film surface was evaluated as "good" when no streaks were observed by brushing, and the film surface was evaluated as "poor" when streaks were observed, and the results are shown in table 2.
[ Table 2]
Figure BDA0003840125500000391
As shown in Table 2 and FIG. 1, it is understood that, as for the results of the evaluation of the transmittance using the liquid crystal aligning agents (A-1) to (A-3) and (C-1) to (C-5) obtained in examples 1 to 8, a liquid crystal alignment film having a higher transmittance can be obtained than the results of the evaluation of the transmittance using the liquid crystal aligning agents (B-1) to (B-3) and (D-1) to (D-5) obtained in comparative examples 1 to 8. Note that the difference of 1% in transmittance is a significant difference in the art. On the other hand, it is found that liquid crystal alignment films having characteristics of the same degree can be obtained in the evaluation of the voltage holding ratio, the residual DC voltage, the residual image characteristics, and the rubbing resistance.
Further, the liquid crystal display elements using the liquid crystal aligning agents (C-1) to (C-3) exhibit high voltage holding characteristics as compared with the liquid crystal display elements using the liquid crystal aligning agents (A-1) to (A-3). That is, by mixing the polyimide solution (1) having no diphenylamine skeleton, a liquid crystal alignment film having a high transmittance can be obtained, and a liquid crystal display element having a high voltage holding ratio can be obtained.
Furthermore, the liquid crystal display element using the liquid crystal aligning agents (C-4) and (C-5) exhibits good abrasion resistance. That is, by mixing the polyimide solution (2) having no diphenylamine skeleton, a liquid crystal alignment film having a high transmittance can be obtained, and a liquid crystal display element exhibiting excellent rubbing resistance can be obtained.
The entire contents of the specification, claims, drawings and abstract of japanese patent application No. 2020-044505, filed on 3/13/2020, are incorporated herein by reference as the disclosure of the specification of the present invention.

Claims (19)

1. A polyimide varnish containing at least one block copolymer selected from the group consisting of a polyimide precursor having a block (b 1) comprising a repeating unit represented by the following formula (1) and a block (b 2) comprising a repeating unit represented by the following formula (2), and a polyimide obtained by imidizing the polyimide precursor,
Figure FDA0003840125490000011
in the formula, X 1 Represents a tetravalent organic group; x 2 A tetravalent organic group derived from a non-cyclic aliphatic tetracarboxylic dianhydride or a tetravalent organic group represented by the following formula (X2); y is 1 A divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton; y is 2 Represents a divalent organic group having a diphenylamine skeleton; two R 1 And R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, two Z' s 1 And Z 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, an alkenyl group having 2 to 10 carbon atoms which may be substituted, an alkynyl group having 2 to 10 carbon atoms which may be substituted, a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group,
Figure FDA0003840125490000012
in the formula (X2), R 21 ~R 24 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group.
2. The polyimide varnish according to claim 1, wherein,
in the formula (1), X 1 Represents at least one selected from the group consisting of structures represented by the following formulae (X1-1) to (X1-12),
Figure FDA0003840125490000021
3. the polyimide varnish according to claim 1 or 2, wherein,
in formula (1), Y 1 Represents at least one selected from the group consisting of a divalent organic group having 3 to 50 carbon atoms and having a structure represented by the following formulae (S1) to (S3), and a divalent organic group having 3 to 50 carbon atoms and not having a structure represented by the following formulae (S1) to (S3),
wherein the divalent organic group having 3 to 50 carbon atoms and not having the structure represented by the formulae (S1) to (S3) do not have a diphenylamine skeleton,
Figure FDA0003840125490000022
in the formula (S1), X 1 And X 2 Each independently represents a single bond, - (CH) 2 ) a -、-CONH-、-NHCO-、-CON(CH 3 ) -, -NH-, -O-, -COO-, -OCO-or- ((CH) 2 ) a1 -A 1 ) m1 -, said- (CH) 2 ) a In the formula, a is an integer of 1 to 15; wherein a1 is an integer of 1 to 15, respectively 1 Each independently represents an oxygen atom or-COO-, m 1 Is 1 to 2; g 1 And G 2 Each independently represents a divalent cyclic group selected from a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms; any hydrogen atom on the cyclic group is optionally substituted; m and n are each independently integers of 0 to 3, m + n is 1 to 4; r 1 Represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms to form R 1 Optionally substituted with fluorine atoms; when m, n and m1 are 2 or more, there are a plurality of X' s 1 、X 2 、G 1 、G 2 A1, m1 and A 1 Each independently having the above-mentioned definitions,
-X 3 -R 2 (S2)
in the formula (S2), X 3 Represents a single bond, -CONH-, -NHCO-, -CON (CH) 3 )-、-NH-、-O-、-CH 2 O-, -COO-or-OCO-; r 2 Represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms to form R 2 Optionally substituted with fluorine atoms,
-X 4 -R 3 (S3)
in the formula (S3), X 4 represents-CONH-) -NHCO-) -O-, -CH 2 O-, -COO-or-OCO-; r is 3 Represents a structure having a steroid skeleton.
4. The polyimide varnish according to claim 3, wherein,
in formula (1), Y 1 At least one of (a) and (b) represents a divalent organic group having 3 to 50 carbon atoms having a structure represented by the formulae (S1) to (S3).
5. The polyimide varnish according to claim 3 or 4, wherein,
in formula (1), Y 1 At least one of (a) and (b) represents a divalent organic group having 3 to 50 carbon atoms and not having the structure represented by the formulae (S1) to (S3).
6. The polyimide varnish according to claim 3 or 5, wherein,
the divalent organic group having 3 to 50 carbon atoms and not having the structure represented by the formulae (S1) to (S3) represents a divalent organic group having a nitrogen-containing heterocycle in the molecule, a divalent organic group having a radical-initiating function, a divalent organic group having a carboxyl group, a group having a group — "N (D) -", a group having photo-alignment properties, a divalent organic group having an oxygen-containing heterocycle, or a divalent organic group derived from an aromatic diamine not having a side chain group having 3 or more carbon atoms, and in the group-N (D) -, D represents a t-butoxycarbonyl group.
7. The polyimide varnish according to any one of claims 1 to 6, wherein,
in the formula (2), X 2 Represents at least one selected from the group consisting of structures represented by the following formulae (X2-1) to (X2-4),
Figure FDA0003840125490000041
8. the polyimide varnish according to any one of claims 1 to 7, wherein,
in formula (2), Y 2 A structure represented by the following formula (d 2),
Figure FDA0003840125490000042
in the formula (d 2), A 1 Represents a single bond, -NR-, -O-, -C (= O) NR-, -C (= O) O-, or a divalent organic group, wherein in-NR-, R represents a hydrogen atom or a monovalent organic group, and in-C (= O) NR-, R represents a hydrogen atom or a monovalent organic group; r 1 、R 2 Each independently represents a hydrogen atom or a monovalent organic group; in the case where n is 2, there are a plurality of A' s 1 And R 2 Each independently having the above definitions.
9. The polyimide varnish according to any one of claims 1 to 8, wherein,
the ratio of the total mole number of the repeating units represented by the formula (1) to the total mole number of the repeating units represented by the formula (2) per one molecule of the block copolymer is 1: 9 to 9: 1.
10. The polyimide varnish according to any one of claims 1 to 9, wherein,
the polyimide varnish further contains at least one polymer (P) selected from the group consisting of a polyimide precursor having a repeating unit represented by the following formula (3) and a polyimide obtained by imidizing the polyimide precursor,
Figure FDA0003840125490000051
in the formula (3), X 3 Represents a tetravalent organic group; y is 3 A divalent organic group having 3 to 50 carbon atoms and having no diphenylamine skeleton; r 3 、Z 3 And R of formula (1) 1 、Z 1 Synonymy; there are two R 3 And Z 3 Each independently having the above definitions.
11. The polyimide varnish according to claim 10, wherein,
the polymer (P) does not have a diphenylamine skeleton.
12. A method for producing a polyimide varnish according to any one of claims 1 to 11, the method comprising:
a step (I) in which a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (1-T) or a derivative thereof is reacted with a diamine component comprising a diamine represented by the following formula (1-D) to obtain a block (b 1); and
a step (II) of adding a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (2-T) or a derivative thereof and a diamine component comprising a diamine represented by the following formula (2-D) to the block (b 1) and reacting them to obtain a polyimide precursor having the block (b 1) and the block (b 2),
Figure FDA0003840125490000052
in the formula, X 1 、X 2 、Y 1 、Y 2 With X as defined in formula (1) and formula (2) 1 、X 2 、Y 1 、Y 2 The same is true.
13. The method for producing a polyimide varnish according to claim 12, wherein,
the reaction temperature in the step (II) is lower than the reaction temperature in the step (I).
14. A method for producing a polyimide varnish according to any one of claims 1 to 11, the method comprising:
a step (III) for reacting a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (1-T) or a derivative thereof with a diamine component comprising a diamine represented by the following formula (1-D) to obtain a block (b 1);
a step (IV) for reacting a tetracarboxylic acid component comprising a tetracarboxylic dianhydride represented by the following formula (2-T) or a derivative thereof with a diamine component comprising a diamine represented by the following formula (2-D) to obtain a block (b 2); and
a step (V) of coupling the block (b 1) obtained in the step (III) with the block (b 2) obtained in the step (IV) to obtain a polyimide precursor having the block (b 1) and the block (b 2),
Figure FDA0003840125490000061
in the formula, X 1 、X 2 、Y 1 、Y 2 With X as defined in formula (1) and formula (2) 1 、X 2 、Y 1 、Y 2 The same is true.
15. The method for producing a polyimide varnish according to claim 14, wherein,
the reaction temperature in the step (IV) is lower than the reaction temperature in the step (III).
16. A liquid crystal aligning agent obtained from the polyimide varnish according to any one of claims 1 to 11.
17. A liquid crystal alignment film formed using the liquid crystal aligning agent according to claim 16.
18. A liquid crystal display element comprising the liquid crystal alignment film according to claim 17.
19. A method for manufacturing a liquid crystal display element comprises the following steps:
the liquid crystal aligning agent according to claim 16 is applied to a pair of substrates having conductive films to form coating films, the coating films are arranged to face each other with a layer of liquid crystal molecules interposed therebetween to form a liquid crystal cell, and the liquid crystal cell is irradiated with light in a state where a voltage is applied between the conductive films of the pair of substrates.
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