JP2019214705A - Method for producing polyamide-imide precursor - Google Patents

Abstract

To provide a method for producing a polyamide-imide precursor having a high molecular weight.SOLUTION: The present invention provides a method for producing a polyamide-imide precursor that at least has a diamine compound-derived constitutional unit, a tetracarboxylic acid compound-derived constitutional unit, and a dicarboxylate compound-derived constitutional unit, the method including a step (I) of reacting a diamine compound with a tetracarboxylic acid compound in a solvent to produce an intermediate (A), and a step (II) of reacting the intermediate (A) with a dicarboxylic acid compound in a solvent, where in the step (II), a further solvent is added.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polyamideimide precursor which is an intermediate of polyamideimide used as a material for a flexible display or the like, and a method for producing the polyamideimide.

  2. Description of the Related Art Image display devices such as liquid crystal display devices and organic EL display devices are widely used in various applications such as mobile phones and smart watches. Glass has been used as a front plate of such an image display device. However, since glass is very rigid and easily broken, it is difficult to use the glass as a front plate material of a flexible display. Polyamide imide is one of the materials replacing glass, and an optical film using the polyamide imide has been studied (Patent Document 1).

JP 2017-203984 A

  The polyamideimide is usually obtained by reacting a component constituting the polyamideimide, for example, an amine compound or a carboxylic acid compound, to obtain a polyamideimide precursor, and then imidizing the polyamideimide precursor. On the other hand, for use in optical film applications, mechanical strength such as flex resistance and elastic modulus is required, so that a high molecular weight polyamide-imide is required. However, according to the study of the present inventors, in the course of the production of polyamide imide, the polyamide imide precursor cannot be sufficiently increased in molecular weight, and the polyamide imide obtained by imidization may not be increased in molecular weight in some cases. all right.

  Accordingly, an object of the present invention is to provide a method for producing a polyamideimide precursor having a high molecular weight, and a method for producing a polyamideimide obtained by imidizing the polyamideimide precursor.

  The present inventor has conducted intensive studies in order to solve the above problems, and as a result, a step of reacting an intermediate (A) produced by reacting a diamine compound and a tetracarboxylic acid compound with a dicarboxylic acid compound in a solvent ( In II), it was found that the above problem could be solved by further adding a solvent, and the present invention was completed. That is, the present invention includes the following preferred embodiments.

[1] A method for producing a polyamideimide precursor having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound,
Step (I) of producing an intermediate (A) by reacting a diamine compound and a tetracarboxylic acid compound in a solvent, and Step (II) of reacting the intermediate (A) with a dicarboxylic acid compound in a solvent Including
In the method (II), a solvent is further added.
[2] The method according to [1], wherein in the step (II), a solvent is further added after adding 60 to 99 mol% of the dicarboxylic acid compound to the total molar amount of the dicarboxylic acid compound to be added.
[3] The method according to [2], wherein in the step (II), a solvent is added simultaneously with or before the addition of the remaining dicarboxylic acid compound.
[4] In the step (II), when adding 60 to 99 mol% of the dicarboxylic acid compound to the total molar amount of the dicarboxylic acid compound to be added n times, and then adding the remaining dicarboxylic acid compound, the following formula (X)
t ₁ / n <t ₂ (X)
Wherein (X), _{t 1} represents the time up to the point of ending from the time of starting the addition of the 60 to 99 mole% of the dicarboxylic acid compound, _{t 2} is the 60 to 99 mole% of the dicarboxylic acid compound Represents the time from the end of the addition to the start of the addition of the remaining dicarboxylic acid compound, and n represents an integer of 1 to 20]
The method according to any one of [1] to [3], which satisfies the following relationship:
[5] In the step (II), after the weight average molecular weight of the polyamideimide precursor reaches 10% or more with respect to the weight average molecular weight of the obtained polyamideimide precursor, a solvent is further added. The method according to any one of [4].
[6] The method according to any one of [1] to [5], wherein in step (II), the substrate concentration after the addition of the solvent is 30 to 80% of the initial substrate concentration before the reaction.
[7] A method for producing a polyamideimide, comprising a step (III) of imidizing the polyamideimide precursor according to any one of [1] to [6] in the presence of an imidation catalyst.

  According to the production method of the present invention, a polyamideimide precursor and a polyamideimide having a high molecular weight can be obtained.

  The polyamideimide precursor obtained by the present invention is a resin having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and a diamine compound and a tetracarboxylic acid compound. In a solvent to produce an intermediate (A), and a step (II) of reacting the intermediate (A) with a dicarboxylic acid compound in a solvent. it can.

<Step (I)>
Step (I) is a step of reacting a diamine compound and a tetracarboxylic acid compound in a solvent to produce an intermediate (A). In this specification, a tetracarboxylic acid compound refers to a tetracarboxylic acid or a tetracarboxylic acid derivative (eg, an acid chloride or an acid anhydride of tetracarboxylic acid).

As the diamine compound, for example, a compound represented by the formula (1)
(Sometimes referred to as diamine compound (1)). The diamine compounds can be used alone or in combination of two or more kinds. When two or more kinds of diamine compounds are used, two or more kinds of diamine compounds having different types of X of the diamine compound (1) may be used.

  In the formula (1), X represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms. The organic group, a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, in which case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably Is 1 to 8. X is represented by Expression (10), Expression (11), Expression (12), Expression (13), Expression (14), Expression (15), Expression (16), Expression (17), or Expression (18). A group in which a hydrogen atom in the group represented by those formulas is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms. You.

In the formula (10) to (18), * represents a ^bond, V 1, ^{V 2} and ^{V 3} independently represents a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 _{-, - CH (CH 3)} -, - C (CH 3) 2 -, - C (CF 3) 2 -, - S -, - representing the or -CO- - SO _2. V ¹ and V ² and V ² and V ³ are each preferably located at the meta or para position with respect to each ring.

Formula (10), Formula (11), Formula (12), Formula (13), Formula (14), Formula (15), Formula (16), Formula (17), or Formula (18) Among them, a group represented by the formula (13), the formula (14), the formula (15), the formula (16) or the formula (17) is preferable from the viewpoint of easily improving the elastic modulus of the optical film containing the polyamideimide. Preferably, a group represented by formula (14), formula (15) or (16) is more preferable. Further, V ¹ , V ² and V ³ are preferably each independently a single bond, -O- or -S-, from the viewpoint of easily improving the elastic modulus of the optical film containing polyamideimide, It is more preferably a single bond or -O-, and further preferably a single bond.

In a preferred embodiment of the present invention, X in formula (1) is represented by formula (2):
[In the formula (2), R ^{1 to} R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{1 to} R ⁸ The atoms may be each independently substituted with a halogen atom, and * represents a bond.
It is represented by When X in the formula (1) contains a compound represented by the formula (2) as the diamine compound, the optical film containing the polyamideimide easily has both high elastic modulus and excellent optical characteristics.

In the formula (1), R ^{1 to} R ⁸ are preferably R ^{1 to} R ⁶ are a hydrogen atom, R ⁷ and R ⁸ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably R ¹ to R ⁸ are R ¹ to R ⁸ . R ⁶ represents a hydrogen atom, R ⁷ and R ⁸ represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein the hydrogen atoms contained in R ⁷ and R ⁸ are each independently substituted with a halogen atom. May be. R ^{1 to} R ⁸ are each independently preferably a methyl group or trifluoromethyl, from the viewpoint of easily obtaining an optical film having excellent optical properties, for example, low haze and low yellowness, comprising polyamideimide. And particularly preferably a trifluoromethyl group.

In a preferred embodiment of the present invention, formula (2) is replaced by formula (2 ′):
It is represented by When the X in the formula (2) includes a compound represented by the formula (2 ′) as the diamine compound, the optical film including the polyamideimide has a reduced haze and a reduced yellowness. As a result, excellent optical characteristics can be obtained. Further, the solubility of the polyamideimide in the solvent is improved by the skeleton containing the fluorine element, the viscosity of the polyamideimide varnish can be suppressed to a low level, and the production of an optical film containing the polyamideimide becomes easy.

  More specifically, examples of the diamine compound include an aliphatic diamine, an aromatic diamine, and a mixture thereof. In the present embodiment, “aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of the structure may include an aliphatic group or another substituent. The aromatic ring may be a single ring or a condensed ring, and includes, but is not limited to, a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring and the like. Among these, a benzene ring is preferred. The “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may have an aromatic ring or another substituent in a part of its structure. The diamine compounds can be used alone or in combination of two or more.

  Specific examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylene diamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4 ′ And cycloaliphatic diamines such as diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

  Specific examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diamino Aromatic diamine having one aromatic ring such as naphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3 '-Diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4′-diaminodiphe Sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2, 2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2′-bis (trifluoromethyl) benzidine (sometimes referred to as TFMB) 4,4′- Bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (4-amino-3 Aromatic diamines having two or more aromatic rings, such as -chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene And the like. These can be used alone or in combination of two or more.

  As the aromatic diamine, preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 3,3′-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2′-bis (Trifluoromethyl) -4,4'-diaminodiphenyl, 4,4'-bis (4-aminophen Xy) biphenyl, and more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 1,4-bis ( 4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2 '-Bis (trifluoromethyl) benzidine and 4,4'-bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of two or more.

  Among the above diamine compounds, it is easy to improve the elastic modulus of the optical film containing polyamideimide, and also to improve the optical properties, for example, from the viewpoint of easily reducing the haze, selected from the group consisting of aromatic diamines having a biphenyl structure. It is preferable to use one or more types. One selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use the above, and it is further preferable to use 2,2′-bis (trifluoromethyl) benzidine.

Among the diamine compounds used in the step (I), X in the formula (1) is a diamine compound represented by the formula (2), for example, X in the formula (1) is represented by the formula (2 ′) The proportion of the diamine compound is preferably at least 30 mol%, more preferably at least 50 mol%, further preferably at least 70 mol%, particularly preferably at least 30 mol%, based on the total molar amount of the diamine compound used in step (I). It is 80 mol% or more, preferably 100 mol% or less. When the proportion of the diamine compound in which X in the formula (1) is represented by the formula (2) is within the above range, the optical film containing the polyamideimide has reduced haze and can have higher transparency. Also, the production of the optical film becomes easy. The ratio of the diamine compound represented by the formula (2) can be measured using, for example, ¹ H-NMR, or can be calculated from the charge ratio of the raw materials.

The tetracarboxylic acid compound used in the step (I) indicates a tetracarboxylic acid or a tetracarboxylic acid derivative. Examples of the tetracarboxylic acid derivative include an anhydride of tetracarboxylic acid, preferably dianhydride, acid chloride and the like.
Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acids and anhydrides thereof, preferably aromatic tetracarboxylic acid compounds such as dianhydrides; aliphatic tetracarboxylic acids and anhydrides thereof, preferably dianhydrides and the like And the like. These tetracarboxylic acid compounds can be used alone or in combination of two or more.

More preferably, the tetracarboxylic acid compound is a tetracarboxylic dianhydride. As the tetracarboxylic dianhydride, for example, a compound represented by the formula (3)
(Sometimes referred to as a tetracarboxylic acid compound (3)). The tetracarboxylic acid compounds can be used alone or in combination of two or more kinds. When two or more kinds of tetracarboxylic acid compounds are used, two or more kinds of tetracarboxylic acid compounds having different types of Y in the tetracarboxylic acid compound (3) are used. May be used.

In the formula (3), each Y independently represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms. The organic group, a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, in which case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably Is 1 to 8. As Y, Equation (20), Equation (21), Equation (22), Equation (23), Equation (24), Equation (25), Equation (26), Equation (27), Equation (28), or A group represented by the formula (29); a group in which a hydrogen atom in the group represented by the formula is substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a tetravalent carbon atom of 6 or less Are exemplified.

In equations (20) to (29),
* Represents a bond,
W ¹ represents a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, _{-Ar -, - SO 2 -,} - CO -, - O-Ar-O -, - Ar-O-Ar -, - Ar-CH 2 -Ar -, - Ar-C (CH 3) 2 -Ar- or an _-Ar-SO 2 -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted with a fluorine atom, and specific examples include a phenylene group. In the formula (3), Y is preferably a group represented by the formulas (26), (28), and (29) from the viewpoint of easily improving the elastic modulus of the optical film containing the polyamideimide. In addition, from the viewpoint of easily reducing the yellowness of the optical film containing polyamideimide, in the formula (3), Y is the formula (20), the formula (21), the formula (22), the formula (23), the formula (23). (24) a group represented by the formula (25), the formula (26) or the formula (27); and a group in which a hydrogen atom in the group is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. Is preferred. In addition, ^{W 1,} from the viewpoint of easily suppressing the yellowness of the optical film comprising a polyamideimide, each independently, preferably a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 - _{, -CH (CH 3) -,} - C (CH 3) 2 - or -C _{(CF 3) 2} -, more preferably a single _{bond, -O -, - CH 2 -} , - C (CH 3) 2 - or -C _{(CF 3) 2} -, more preferably -C _{(CH 3) 2} - or -C _{(CF 3) 2} - a -, especially preferably -C _{(CF 3) 2.}

In a preferred embodiment of the present invention, Y in formula (3) is represented by formula (4)
[In the formula (4), R ^{9 to} R ¹⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{9 to} R ¹⁶ The atoms may be each independently substituted with a halogen atom, and * represents a bond.
It is represented by

In the formula (4), R ^{9 to} R ¹⁴ are preferably a hydrogen atom, R ¹⁵ and R ¹⁶ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably, R ^{9 to} R ¹⁴ are a hydrogen atom, R ^{9 15} and R ¹⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein the hydrogen atoms contained in R ¹⁵ and R ¹⁶ may be each independently substituted with a halogen atom. R ¹⁵ and R ¹⁶ are each independently preferably a methyl group from the viewpoint that the elastic modulus of the optical film containing polyamideimide is easily improved and the optical characteristics are easily improved, for example, the yellowness is easily reduced. , A fluoro group, a chloro group or a trifluoromethyl group, particularly preferably a methyl group or a trifluoromethyl group.

In a preferred embodiment of the present invention, formula (4) is replaced by formula (4 ′):
It is represented by When Y in the formula (4) contains a tetracarboxylic acid compound represented by the formula (4 ′) as the tetracarboxylic acid compound, the optical film comprising the polyamideimide has a reduced haze and an all-light Since the transmittance can be increased, it has excellent transparency. Further, the solubility of the polyamideimide in the solvent can be improved by the skeleton containing a fluorine element, the viscosity of the polyamideimide varnish can be suppressed low, and the production of the optical film becomes easy.

  Specific examples of the aromatic tetracarboxylic dianhydride include a non-condensed polycyclic aromatic tetracarboxylic dianhydride, a monocyclic aromatic tetracarboxylic dianhydride and a condensed polycyclic aromatic tetracarboxylic acid. Carboxylic dianhydrides are mentioned. Examples of the non-fused polycyclic aromatic tetracarboxylic dianhydride include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and 2,2 ′ , 3,3′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxy) Phenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (referred to as 6FDA) ), 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3 4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3 -Dicarboxyphenyl) methane dianhydride, 4,4 '-(p-phenylenedioxy) diphthalic dianhydride and 4,4'-(m-phenylenedioxy) diphthalic dianhydride. Further, examples of the monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and as a condensed polycyclic aromatic tetracarboxylic dianhydride, Is 2,3,6,7-naphthalenetetracarboxylic dianhydride.

  Among these, 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride are preferred. Anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyl Sulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2- Bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl) eta Dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3 4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 ′-(p-phenyl Examples thereof include dioxy) diphthalic dianhydride and 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride, and more preferably 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4 4,4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride, bis (3 , 4-Zikal Kishifeniru) methane dianhydride, and 4,4 '- (p- phenylene-oxy) diphthalic acid dianhydride. These can be used alone or in combination of two or more.

  Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. A cycloalkanetetracarboxylic dianhydride such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2 .2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3 ′, 4,4′-tetracarboxylic dianhydride and positional isomers thereof. Can be These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. And these can be used alone or in combination of two or more. Further, a combination of a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used.

  Among the tetracarboxylic acid compounds, the alicyclic tetracarboxylic dianhydride or the non-condensed polycyclic from the viewpoint of easily improving the elastic modulus, bending resistance, and optical properties of the optical film containing polyamideimide. Is preferred. Specific examples include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-di Carboxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride and mixtures thereof are preferred, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride and a mixture thereof are more preferable, and 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride is further preferable. Masui.

As the tetracarboxylic acid compound, tetracarboxylic dianhydride is preferable, but tetracarboxylic monoanhydride may be used. The tetracarboxylic monoanhydride is represented by the formula (5)
(Sometimes referred to as a tetracarboxylic acid compound (5)). The tetracarboxylic acid compound (5) can be used alone or in combination of two or more kinds. When two or more kinds of the tetracarboxylic acid compounds (5) are used, two kinds of tetracarboxylic acid compounds (5) in which the types of Y ¹ are different from each other are used. The above tetracarboxylic acid compound (5) may be used.

In the formula (5), Y ¹ is a tetravalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The Y ^1, equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), equation (28) or Examples include the group represented by the formula (29) and a tetravalent chain hydrocarbon group having 6 or less carbon atoms. Further, R ¹⁷ and R ¹⁸ are each independently -OH, -OMe, -OEt, -OPr, -OBu or -Cl, and preferably -Cl.

  In the step (I), the ratio (use amount) of the tetracarboxylic acid compound can be appropriately selected depending on the desired ratio of the constituent units of the polyamideimide, and is preferably 0.01 mol or more based on 1 mol of the diamine compound. , More preferably at least 0.05 mol, even more preferably at least 0.1 mol, preferably at most 1.5 mol, more preferably at most 1 mol, even more preferably at most 0.8 mol, particularly preferably at most 0.8 mol. 5 mol or less, and any combination of these upper and lower limits may be used. When the proportion (use amount) of the tetracarboxylic acid compound is in the above range, the imide skeleton is appropriately introduced, the bending resistance of the formed film is improved, and the polyamideimide precursor is easily made to have a high molecular weight.

  The solvent used in the step (I) is not particularly limited as long as it does not affect the reaction. For example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, Alcohol solvents such as 1-methoxy-2-propanol, 2-butoxyethanol and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-valerolactone, propylene glycol methyl ether acetate; Ester solvents such as ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone Solvents; aliphatic hydrocarbon solvents such as pentane, hexane, heptane and the like; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxyethane Ether solvents; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ethylene carbonate, propylene Carbonate-based solvents such as carbonate; and combinations thereof (mixed solvents). Among these, amide solvents can be preferably used from the viewpoint of solubility of the diamine compound and the tetracarboxylic acid compound.

  The amount of the solvent used is preferably 0.5 to 30 parts by mass, more preferably 1 to 25 parts by mass, and still more preferably 5 to 20 parts by mass, based on 1 part by mass of the total amount of the diamine compound and the tetracarboxylic acid compound. It is. When the content of the solvent is not less than the above lower limit, it is advantageous from the viewpoint of suppressing the increase in viscosity in the step (III), and when it is not more than the above upper limit, it is advantageous from the viewpoint of polymerization reaction.

  The reaction temperature in step (I) is not particularly limited, but may be, for example, 15 to 200 ° C, preferably 20 to 100 ° C, more preferably 20 to 50 ° C, and further preferably room temperature (about 25 ° C). The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours. The reaction may be performed with stirring in air or an inert gas atmosphere (for example, nitrogen, argon, or the like), and may be performed under normal pressure, under pressure, or under reduced pressure. In a preferred embodiment, the reaction is carried out under normal pressure and / or an inert gas atmosphere with stirring.

As described above, in the step (I), the diamine compound and the tetracarboxylic acid compound react to form the intermediate (A), that is, the polyamic acid. Therefore, the intermediate (A) has at least a structural unit derived from a diamine compound and a structural unit derived from a tetracarboxylic acid compound. In a preferred embodiment, the intermediate (A) includes a repeating structural unit represented by the formula (A) obtained by reacting the diamine compound (1) with the tetracarboxylic acid compound (3).
[In the formula (A), G ¹ is the same as Y in the formula (3), and X ¹ is the same as X in the formula (1)]

  When there are two or more kinds of the diamine compound (1) and / or the tetracarboxylic acid compound (3), the intermediate (A) has two or more kinds of the repeating structural units represented by the formula (A). In the production method of the present invention, the intermediate (A) obtained in the step (I) may be isolated and subjected to the step (II). However, usually, the intermediate (A) is continuously isolated without isolation. To serve.

<Step (II)>
Step (II) is a step of reacting the intermediate (A) with the dicarboxylic acid compound in a solvent, and is characterized by further adding a solvent.

The dicarboxylic acid compound indicates a dicarboxylic acid or a dicarboxylic acid derivative, and examples of the dicarboxylic acid derivative include acid chlorides and esters of the dicarboxylic acid. As the dicarboxylic acid compound, for example, a compound represented by the formula (6)
(Sometimes referred to as dicarboxylic acid compound (6)). The dicarboxylic acid compounds can be used alone or in combination of two or more. When two or more dicarboxylic acid compounds are used, two or more dicarboxylic acid compounds (6) having different types of W from each other are used. May be. In the formula (6), R ¹⁹ and R ²⁰ are each independently -OH, -OMe, -OEt, -OPr, -OBu or -Cl, and preferably -Cl.

  In the formula (6), W represents a divalent organic group, and preferably represents a divalent organic group having 4 to 40 carbon atoms. The organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. In this case, the hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. As W, equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), equation (28) or equation Examples of the bond of the group represented by (29) include a group in which two non-adjacent atoms are replaced by hydrogen atoms, a group represented by the formula (7a), and a divalent chain hydrocarbon group having 6 or less carbon atoms. Is done. A compound in which W in the formula (6) contains a group represented by the formula (7a) may be referred to as an aromatic dicarboxylic acid compound (A).

[In the formula (7a), R ^{21 to} R ²⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{21 to} R ²⁴ The atoms may be each independently substituted with a halogen atom, m is an integer of 1 to 4, and * represents a bond.

  In the embodiment of the present invention, from the viewpoint of improving the optical characteristics of the optical film containing polyamideimide, for example, from the viewpoint of easily reducing the yellowness, the formula (20), the formula (21), the formula (22), and the formula (23) Of the bonds represented by the formulas (24), (25), (26) or (27), in which two non-adjacent atoms are replaced by hydrogen atoms; and the formula (7a) Groups are preferred.

In a preferred embodiment of the present invention, from the viewpoint of improving the mechanical strength of the optical film containing polyamideimide, for example, from the viewpoint of easily increasing the elastic modulus, the dicarboxylic acid compound is represented by the formula (1) wherein W in the formula (26) , A group in which two non-adjacent bonds are replaced by a hydrogen atom among the bonds of the group represented by the formula (28) or the formula (29); and a dicarboxylic acid compound containing a group represented by the formula (7a) is preferable. From the viewpoints of availability of raw materials and good solubility in organic solvents, m in the formula (7a) is more preferably 1 to 2, and further preferably 1 is m. Further, when all of R ^{21 to} R ²⁴ in the formula (7a) are hydrogen atoms, it is more advantageous from the viewpoint of improving the elastic modulus of an optical film containing polyamideimide.

  In a preferred embodiment of the present invention, from the viewpoint that an optical film comprising polyamide imide easily develops good bending resistance, the dicarboxylic acid compound has two or more aromatic hydrocarbon rings having a single bond and an aromatic hydrocarbon ring. Includes aromatic dicarboxylic acid compounds linked by a divalent group other than the group. Examples of the aromatic hydrocarbon ring include a monocyclic hydrocarbon ring such as a benzene ring; a polycyclic hydrocarbon ring such as a condensed bicyclic hydrocarbon ring such as naphthalene and a ring-assembled hydrocarbon ring such as biphenyl. , Preferably a benzene ring.

Specifically, in the aromatic dicarboxylic acid compound in which two or more aromatic hydrocarbon rings are linked by a single bond and a divalent group other than the aromatic group, in the formula (6), W is represented by the formula (7b )
[In formula (7b), R ^{25 to} R ³² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{25 to} R ³² The atoms may be each independently substituted with a halogen atom, m ¹ is an integer of ¹ to 4, m ² is 0 or 1, A ¹ and A ² are each independently —O— _{, -CH 2 -, - CH 2} -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, - S -, - SO 2 -, - CO- or ^{-NR 34} - ^{represents, R 34} represents a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms, * represents a bond]
It is preferable that the compound contains a group represented by Note that a compound in which W in the formula (6) contains a group represented by the formula (7b) may be referred to as an aromatic dicarboxylic acid compound (B).

In the formula (7b), A ¹ and A ² are each independently, preferably -O, from the viewpoint that the drying temperature is easily lowered and the optical film containing the polyamideimide easily has good bending resistance. _{-, - CH 2 -, -} C (CH 3) 2 -, - C (CF 3) 2 -, - S- or -SO ₂ -; more preferably, _{-O -, - CH 2 -,} - C It represents (CH ₃ ) ₂ — or —SO ₂ —, and more preferably represents —O—. R ^{25 to} R ³² preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, from the viewpoint of availability of raw materials and good mechanical strength. Represents a group, and more preferably represents a hydrogen atom. Here, the hydrogen atoms contained in R ^{25 to} R ³² may be each independently substituted with a halogen atom. Further, m ¹ is preferably 1 or 2, and more preferably 1. m ² is preferably 0.

In a more preferred embodiment of the present invention, formula (7b) is replaced by formula (7b ′):
It is represented by When W in the formula (6) contains a compound represented by the formula (7b ′) as the dicarboxylic acid compound, the optical film containing the polyamideimide has higher mechanical strength (for example, elastic modulus or flex resistance). Easy to improve).

Specific examples of the dicarboxylic acid compound include, for example, 4,4′-oxybisbenzoic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, and two benzoic acids acid is a single _{bond, -CH 2 -, - C (} CH 3) 2 -, - C (CF 3) 2 -, - SO 2 - or aromatic dicarboxylic acids and derivatives of these compounds or the like which is connected by a phenylene group (E.g., acid chlorides and acid anhydrides); aliphatic dicarboxylic acids such as dicarboxylic acid compounds of chain hydrocarbons having 8 or less carbon atoms, and derivatives thereof (e.g., acid chlorides and esters). These dicarboxylic acid compounds can be used alone or in combination of two or more. Among them, it is preferable to use the aromatic dicarboxylic acid compound (A) and the aromatic dicarboxylic acid compound (B) in combination from the viewpoint of achieving both the elastic modulus and the bending resistance of the optical film. Specifically, a combination of 4,4′-oxybis (benzoyl chloride) and terephthaloyl chloride is preferably used.

  In the step (II), a solvent is further added to the reaction solution obtained in the step (I). By adding a solvent in the step (II), in the reaction between the intermediate (A) and the dicarboxylic acid compound, a rapid increase in the viscosity of the reaction system is suppressed, and a state where uniform stirring is possible is maintained for a long time. Can be. Therefore, the polymerization reaction can sufficiently proceed, and the obtained polyamideimide precursor can have a high molecular weight.

  Examples of the solvent include the solvents exemplified in the section of <Step (I)>, and these solvents can be used alone or in combination of two or more. An amide-based solvent can be suitably used from the viewpoint of good solubility and easily increasing the molecular weight of the polyamideimide precursor. The solvent used in step (II) may be different from the solvent used in step (I), but it is preferable to use the same solvent.

  In the step (II), the solvent may be added at once, or may be added in a plurality of divided portions as long as an amount capable of suppressing a sharp increase in viscosity is added. From the viewpoint of workability, it is preferable to add once or twice.

  The amount of the solvent added in the step (II) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, particularly preferably 1 part by mass with respect to 1 part by mass of the dicarboxylic acid compound to be added. Is not less than 20 parts by mass, preferably not more than 300 parts by mass, more preferably not more than 200 parts by mass, still more preferably not more than 100 parts by mass, particularly preferably not more than 50 parts by mass, and any combination of these upper and lower limits. It may be. When the amount of the solvent added in the step (II) is within the above range, the molecular weight of the polyamideimide precursor is easily improved.

  The total amount of the solvent used in the step (I) and the step (II) is the diamine compound and the tetracarboxylic acid compound used in the step (I) or the intermediate (A) and the dicarboxylic acid used in the step (II). It is preferably at least 0.5 part by mass, more preferably at least 1 part by mass, still more preferably at least 3 parts by mass, preferably at most 100 parts by mass, more preferably at most 50 parts by mass, based on 1 part by mass of the total amount of the compound. Hereinafter, the content is more preferably 30 parts by mass or less, and any combination of these upper and lower limits may be used. When the total amount of the solvents used in the step (I) and the step (II) is within the above range, the molecular weight of the polyamideimide precursor is easily improved.

  In the step (II), the dicarboxylic acid compound may be added all at once or may be added in portions, but is preferably added in portions. When added in portions, it is easy to suppress a sudden increase in the viscosity of the reaction system, and it is easy to maintain a uniformly stirable state for a long time. Therefore, the polymerization reaction easily proceeds, and the molecular weight of the obtained polyamideimide precursor is easily improved. In the present specification, the divisional addition means that the dicarboxylic acid compound to be added is added in several steps, more specifically, the dicarboxylic acid to be added is divided into specific amounts and separated at predetermined intervals (predetermined time). It means adding each. Since the predetermined interval (predetermined time) includes a very short interval (or time), the divisional addition includes continuous addition (or continuous feed).

  In the step (II), the number of divisions when the dicarboxylic acid compound is dividedly added can be appropriately selected depending on the reaction scale, the type of the raw material, and the like, and is preferably 2 to 20, more preferably 2 to 10, and still more preferably 3 to 10. ~ 6 times. When the number of divisions is within the above range, the obtained polyamide-imide precursor tends to have a higher molecular weight.

  The dicarboxylic acid compound may be divided and added in equal amounts, or may be divided and added in unequal amounts. The time between each addition (sometimes referred to as the addition interval) may be the same or different. When two or more dicarboxylic acid compounds are added, the term "split addition" means that the total amount of all dicarboxylic acid compounds is added in a divided manner, and the method of dividing each dicarboxylic acid compound is particularly limited. However, for example, each dicarboxylic acid compound may be separately added all at once or dividedly, each dicarboxylic acid compound may be separately added together, or a combination thereof.

  In one embodiment of the present invention, when there are two types of dicarboxylic acid compounds (referred to as a first dicarboxylic acid compound and a second dicarboxylic acid compound, respectively), for example, the first dicarboxylic acid compound is added at once, and the second dicarboxylic acid compound is added. The compounds may be added all at once, the first dicarboxylic acid compound and the second dicarboxylic acid compound may be separately added separately, or the first dicarboxylic acid compound and the second dicarboxylic acid compound may be separately added together. Alternatively, after the portions are added together, the remaining portions may be added separately or one of the remaining portions may be added. After the portions are separately added, the remaining portions may be added together or one of the remaining portions may be added. From the viewpoint of increasing the molecular weight of the polyamideimide precursor, it is preferable that the first dicarboxylic acid compound and the second dicarboxylic acid compound are separately added together, or that the remaining one of the two is added after being added together.

  In the step (II), the ratio (used amount) of the dicarboxylic acid compound to be added can be appropriately selected depending on the desired ratio of the constituent units of the polyamideimide precursor. For example, the ratio is preferably 0 to 1 mol of the diamine compound. 0.05 mol or more, more preferably 0.1 mol or more, still more preferably 0.3 mol or more, preferably 1.5 mol or less, more preferably 1.2 mol or less, and still more preferably 1 mol or less. Any combination of these upper and lower limits may be used. When the ratio (use amount) of the dicarboxylic acid compound is in the above range, a polyamideimide having a high elastic modulus is obtained, and the molecular weight of the polyamideimide precursor is easily improved.

In one embodiment of the present invention, the aromatic dicarboxylic acid compound (A) and the aromatic dicarboxylic acid compound (B) are preferably used in combination as the dicarboxylic acid compound. In this case, the ratio (use amount) of the aromatic dicarboxylic acid compound (B) is preferably 0.01 mol or more, more preferably 0.05 mol or more, based on 1 mol of the aromatic dicarboxylic acid compound (A). It is still more preferably 0.1 mol or more, preferably 20 mol or less, more preferably 15 mol or less, and still more preferably 10 mol or less, and any combination of these upper and lower limits may be used. When the proportion of the aromatic dicarboxylic acid compound (B) is within the above range, the film after film formation can easily achieve both flexibility and elastic modulus, and can easily improve the molecular weight of the polyamideimide precursor.
In addition, the aromatic dicarboxylic acid compound (A) and the aromatic dicarboxylic acid compound (B) are preferably added together and separately from the viewpoint of easily increasing the molecular weight of the polyamideimide precursor, and are added together or separately. Thereafter, it is more preferable to add the remaining one of them.

  In step (II), the solvent may be added together with the dicarboxylic acid compound, may be added separately from the dicarboxylic acid, or may be a combination of these when the dicarboxylic acid is added in portions. May be.

  In one embodiment of the present invention (which may be referred to as aspect (A)), it is possible to further add a solvent after adding 60 to 99 mol% of the dicarboxylic acid compound based on the total molar amount of the dicarboxylic acid compound to be added. preferable. When added at such a timing, a rapid increase in viscosity is effectively suppressed, and a state where uniform stirring is possible is easily maintained, so that the progress of the polymerization reaction of the polyamideimide precursor and the increase in the molecular weight can be effectively performed. Further, it is particularly effective to add a solvent after adding the dicarboxylic acid compound in an amount of preferably 70 to 95 mol%, more preferably 80 to 95 mol%, based on the total molar amount of the dicarboxylic acid compound to be added, When the amount of the dicarboxylic acid compound to be added is within the above range, the molecular weight of the polyamideimide precursor is easily improved. In this embodiment, it is particularly preferable to add the solvent simultaneously with or before the addition of the remaining dicarboxylic acid compound. By adding at such a timing, it is possible to more effectively increase the molecular weight of the polyamideimide precursor. In these embodiments, the method of adding the dicarboxylic acid compound is not particularly limited as long as the solvent is added at the timing described above. For example, the dicarboxylic acid compound may be dividedly added twice or three times or more. Often, two or more dicarboxylic acid compounds may be used. Further, as long as the solvent is added at the above timing, the solvent may be added all at once or may be added in portions.

In one embodiment of the present invention (sometimes referred to as aspect (B)), in step (II), 60 to 99 mol% of the dicarboxylic acid compound is added n times with respect to the total molar amount of the dicarboxylic acid compound to be added. After addition (sometimes referred to as pre-addition), when the remaining dicarboxylic acid compound is added (collectively added) (sometimes referred to as post-addition), the formula (X)
t ₁ / n <t ₂ (X)
Wherein (X), _{t 1} represents the time up to the point of ending from the time of starting the addition of the 60 to 99 mole% of the dicarboxylic acid compound, _{t 2} is the 60 to 99 mole% of the dicarboxylic acid compound Represents the time from the end of the addition to the start of the addition of the remaining dicarboxylic acid compound, and n represents an integer of 1 to 20]
Satisfy the relationship.

In the formula (X), t ₁ / n is determined during the addition of the dicarboxylic acid compound of 60 to 99 mol% n times, that is, once (n = 1) or n times. Mean time (sometimes referred to as an average addition interval). When n is 2 or more and at least one of the addition intervals is different, even if the formula (X) is satisfied, an arbitrary addition interval may be longer than t _2. it is preferably shorter than t _2. When n is 1, t ₁ represents the time from the start of addition of one dose to the end thereof. When the relationship represented by the formula (X) is satisfied, a state where uniform stirring is possible is easily maintained, so that the molecular weight of the polyamideimide precursor can be improved.

  The amount of the pre-added dicarboxylic acid compound is preferably 70 to 95 mol%, more preferably 80 to 95 mol%, based on the total molar amount of the dicarboxylic acid compound to be added (pre-addition and post-addition). When the amount of the pre-added dicarboxylic acid compound is within the above range, the molecular weight of the polyamideimide precursor is easily improved.

In the formula (X), the relationship of t ₁ / n <t ₂ may be satisfied, but from the viewpoint of easily improving the molecular weight of the polyamideimide precursor, the difference between t ₂ and t ₁ / n is 10 minutes or more. The time is preferably, more preferably 20 minutes or more, and particularly preferably 30 minutes or more. The upper limit of t ₂ is not particularly limited, from the viewpoint of productivity, for example, the difference between t ₂ and t _{1 /} n may be less than 5 hours.

  In the formula (X), n is 1 to 19, more preferably 1 to 9, and further preferably 2 to 5. In each addition, the amount added may be the same or different.

  In the step (II), it is more preferable to combine at least the embodiments (A) and (B). That is, in step (II), after adding 60 to 99 mol% of the dicarboxylic acid compound to the total molar amount of the dicarboxylic acid compound to be added n times, and then adding the remaining dicarboxylic acid compounds (collective addition), More preferably, the solvent is added after satisfying the relationship of formula (X) and adding the dicarboxylic acid compound in an amount of 60 to 99 mol% based on the total molar amount of the dicarboxylic acid compound to be added. Further, it is more preferable to add a solvent simultaneously with or before the addition of the remaining dicarboxylic acid compound. In the embodiment according to such a combination, the effect of the present invention can be effectively improved, and a polyamideimide precursor having a higher molecular weight can be obtained.

  In one embodiment of the present invention, in step (II), the substrate concentration after the addition of the solvent is preferably 30 to 80%, more preferably 40 to 60%, based on the initial substrate concentration before the reaction. More preferred. When the substrate concentration after the addition of the solvent is within the above range, the obtained polyamide-imide precursor tends to have a high molecular weight. The substrate concentration indicates the mass of the raw material for producing the polyamideimide precursor and the total mass of the raw material and the solvent.

  In one embodiment of the present invention, in step (II), the weight average molecular weight of the polyamideimide precursor has reached 10% or more, more preferably 15% or more, based on the weight average molecular weight of the obtained polyamideimide precursor. It is preferable to add a solvent later, for example, at the time of 10 to 40%, preferably at the time of 15 to 30%. When the solvent is added at such a timing, the obtained polyamide-imide precursor tends to have a high molecular weight.

  The reaction temperature in step (II) is not particularly limited, but may be, for example, 15 to 200 ° C, preferably 20 to 100 ° C, more preferably 20 to 50 ° C, and even more preferably room temperature (about 25 ° C). The reaction may be performed with stirring in air or an inert gas atmosphere (for example, nitrogen, argon, or the like), and may be performed under normal pressure, under pressure, or under reduced pressure. In a preferred embodiment, the reaction is performed with stirring under normal pressure and / or an inert gas atmosphere.

  In the step (II), a polyamideimide precursor is obtained by adding a dicarboxylic acid compound and a solvent and then performing a reaction by stirring or the like for a predetermined time. The polyamideimide precursor can be isolated, for example, by adding a large amount of water or the like to a reaction solution containing the polyamideimide precursor to precipitate the polyamideimide precursor, and performing filtration, concentration, drying, and the like.

In the step (II), the intermediate (A) reacts with the dicarboxylic acid compound to obtain a polyamideimide precursor. Therefore, the polyamideimide precursor refers to a polyamideimide before imidization (before ring closure) having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid, and a structural unit derived from a dicarboxylic acid compound. For example, the polyamide-imide precursor is composed of a repeating structural unit represented by the formula (A) and a repeating structural unit represented by the formula (B) obtained by reacting the intermediate (A) with the dicarboxylic acid compound (6). And
[In the formulas (A) and (B), G ² is the same as W in the formula (6), G ¹ is the same as Y in the formula (3), and X ¹ and X ² are respectively X in formula (1) is the same, and X ¹ and X ² may be the same or different.]

  The polyamideimide precursor can be produced by imidizing the polyamideimide precursor obtained by the production method of the present invention in step (III). Generally, if the weight average molecular weight (Mw) of the polyamideimide precursor is large, the weight average molecular weight (Mw) of the polyamideimide obtained by imidization becomes large. Since the polyamideimide precursor obtained by the production method of the present invention has a high molecular weight, a polyamideimide having a sufficiently high molecular weight can be obtained.

  The weight average molecular weight (Mw) of the polyamideimide precursor is preferably 550,000 or more, more preferably 700,000 or more, further preferably 800,000 or more, particularly preferably 900,000 or more, in terms of standard polystyrene. , Preferably 2,000,000 or less, more preferably 1,500,000 or less, and any combination of these upper and lower limits may be used. In addition, Mw can be measured by gel permeation chromatography (GPC).

  The polyamideimide precursor may further include a structural unit derived from a tricarboxylic acid compound. The polyamideimide precursor containing a structural unit derived from a tricarboxylic acid compound is produced, for example, by a method of adding a tricarboxylic acid compound together with or separately from a tetracarboxylic acid compound in step (I), and reacting the diamine compound with the tricarboxylic acid compound. It may be produced by a method in which a tricarboxylic acid compound is added together or separately with a dicarboxylic acid compound in the step (II), and the intermediate (A) is reacted with the tricarboxylic acid compound.

  The tricarboxylic acid compound is a tricarboxylic acid or a tricarboxylic acid derivative, and examples of the tricarboxylic acid derivative include an acid chloride and an ester of tricarboxylic acid.

As the tricarboxylic acid compound, for example, a compound represented by the formula (8)
(Sometimes referred to as tricarboxylic acid compound (8)). Tricarboxylic acid compounds may be used either singly or in combination, when using a tricarboxylic acid compound two or more tricarboxylic acid compounds (8) of Y ² kinds having different two or more kinds of tricarboxylic acid compound (8) May be used. In the formula (8), R ³³ is —OH, —OMe, —OEt, —OPr, —OBu, or —Cl, preferably —Cl.

In the formula (8), Y ² is a trivalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or Examples include a group in which any one of the bonding hands of the group represented by the formula (29) is replaced by a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and derivatives thereof (for example, acid chlorides and acid anhydrides). Specific examples thereof include 1,2,4-benzenetricarboxylic acid. anhydride; 2,3,6-naphthalene tricarboxylic acid-2,3-anhydride; and phthalic anhydride and benzoic acid is a single _{bond, -O -, - CH 2 -} , - C (CH 3) 2 -, Compounds linked by —C (CF ₃ ) ₂ —, —SO ₂ — or a phenylene group are exemplified. These tricarboxylic acid compounds can be used alone or in combination of two or more.

In one embodiment of the present invention, a structural unit derived from a diamine compound (1), a structural unit derived from a tetracarboxylic acid compound (3), a structural unit derived from a dicarboxylic acid compound (6), and a structural unit derived from a tricarboxylic acid compound (8). The polyamideimide precursor having at least a structural unit includes a repeating structural unit represented by the formula (A), a repeating structural unit represented by the formula (B), and a repeating structural unit represented by the formula (C). Including.
[In the formula (C), G ³ is the same as Y ² in the formula (8), and X ³ is the same as X in the formula (1)]

In one embodiment of the present invention, a structural unit derived from a diamine compound (1), a structural unit derived from a tetracarboxylic acid compound (3), a structural unit derived from a dicarboxylic acid compound (6), and a structural unit derived from a tricarboxylic acid compound (8). The polyamide imide having at least the structural unit derived from the tetracarboxylic acid compound (5) in addition to the structural unit includes a repeating structural unit represented by the formula (A), a repeating structural unit represented by the formula (B), and It contains a repeating structural unit represented by the formula (D) in addition to the repeating structural unit represented by the formula (C).
Wherein (D), ^{G 4} is the same as ^{Y 1} in the formula (5), ^{X 4} is the same as X in the formula ^{(1), R 18} is ^{R 18} in the formula (5) Is the same as

  In the case of producing a polyamideimide, after the polyamideimide precursor is isolated, it may be subjected to the step (III) (imidization step) described below. However, from the viewpoint of production efficiency, the step (III) is directly performed without isolation. ) Is preferred.

<Step (III)>
Step (III) is a step of imidizing a polyamideimide precursor in the presence of an imidization catalyst. For example, by subjecting a polyamide-imide precursor containing a repeating structural unit represented by the formula (A) and a repeating structural unit represented by the formula (B) to the step (III), the structural unit of the polyamide-imide precursor is obtained. Of these, the repeating structural unit represented by the formula (A) is imidized (ring closed), and includes a repeating structural unit represented by the formula (E) and a repeating structural unit represented by the formula (B). A polyamide imide can be obtained.
[In the formulas (B) and (E), G ¹ is the same as W in the formula (6), G ² is the same as Y in the formula (3), and X ¹ and X ² are respectively X in formula (1) is the same, and X ¹ and X ² may be the same or different.]

  Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydro. Alicyclic amines (monocyclic) such as azepine; azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and azabicyclo [3.2. 2] alicyclic amines such as nonane (polycyclic); pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), Ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethyl Pyridine, 3,4-cyclopentenopyridine pyridine, 5,6,7,8-tetrahydroisoquinoline, and aromatic amines isoquinoline.

  The amount of the imidation catalyst to be used is preferably 0.1 to 10 mol, more preferably 1 to 5 mol, per 1 mol of the tetracarboxylic acid compound used in the step (I).

  In the step (III), from the viewpoint of facilitating the imidization reaction, it is preferable to use an acid anhydride together with the imidization catalyst. Examples of the acid anhydride include conventional acid anhydrides and the like used in the imidization reaction. Specific examples thereof include acetic anhydride, propionic anhydride, aliphatic acid anhydrides such as butyric anhydride, and aromatic acids such as phthalic acid. Acid anhydride and the like.

  When an acid anhydride is used, the amount of the acid anhydride is preferably 0.5 to 25 mol, more preferably 1 to 20 mol, and still more preferably 5 to 15 mol, per 1 mol of the tetracarboxylic acid compound. It is.

  The reaction temperature in step (III) is not particularly limited, but may be, for example, 15 to 100 ° C, preferably 20 to 80 ° C. The reaction time may be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours, more preferably 30 minutes to 12 hours. The reaction may be performed with stirring in air or an inert gas atmosphere (for example, nitrogen, argon, or the like), and may be performed under normal pressure, under pressure, or under reduced pressure. In a preferred embodiment, the reaction is performed with stirring under normal pressure and / or an inert gas atmosphere.

  The polyamideimide obtained in the step (III) is isolated (separated and purified) by a conventional method, for example, a separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination thereof. In a preferred embodiment, a large amount of water or the like is added to the reaction solution containing the polyamideimide to precipitate the polyamideimide, which can be isolated by concentration, filtration, drying, and the like.

  Since the polyamideimide obtained in the step (III) has a high molecular weight, it can be used for forming an optical film having mechanical strength such as bending resistance and high elastic modulus. Therefore, it can be suitably used as a front plate material of an image display device such as a liquid crystal display device and an organic EL display device.

  The weight average molecular weight (Mw) of the polyamideimide is preferably 350,000 or more, more preferably 370,000 or more, preferably 1,000,000 or less, more preferably 950,000 or less, in terms of standard polystyrene. Yes, any combination of these upper and lower limits may be used. In addition, Mw can be measured by gel permeation chromatography (GPC).

  The polyamide imide obtained by the production method of the present invention has at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound. In a preferred embodiment, the polyamideimide contains a repeating structural unit represented by the formula (E) and a repeating structural unit represented by the formula (B).

<Measurement of weight average molecular weight (Mw)>
Gel permeation chromatography (GPC) measurement (1) Pretreatment method Intermediate polymer, polyamideimide precursor: 20 mg of air-dried polymer was weighed, 5 mL of DMF eluent (10 mmol lithium bromide solution) was added, and room temperature was maintained for 5 minutes. Then, the mixture was stirred and dissolved to prepare a measurement solution.
Polyamideimide: A DMF eluent (10 mmol lithium bromide solution) was added to a concentration of 2 mg / mL, heated with stirring at 80 ° C. for 30 minutes, cooled, filtered through a 0.45 μm membrane filter, and measured. And

(2) Measurement condition column: TSKgel α-2500 ((7) 7.8 × 300) × 1, one α-M ((13) 7.8 × 300 × 2) manufactured by Tosoh Eluent: DMF (10 mmol Lithium bromide added)
Flow rate: 1.0 mL / min Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μL
Molecular weight standard: Standard polystyrene

<Viscosity of reaction liquid>
It measured using Brookfield E type viscometer DV-II + Pro according to JIS 8803: 2011. The measurement temperature was 25 ° C.

[Example 1]
Nitrogen was passed through a 1 L separable flask equipped with a sufficiently dried stirrer and thermometer for 30 minutes or more, and the inside of the vessel was replaced with nitrogen. 251 g of dimethylacetamide (DMAc) is placed in a flask, and 14.8 g (46.2 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and 4,4 ′-(hexafluoroisopropylidene) diphthalate are added at room temperature. 6.13 g (13.8 mmol) of acid dianhydride (6FDA) was added, and the mixture was stirred for 15 minutes or more, and then left for 16 hours (step (I)).
Next, 0.679 g (2.30 mmol) of 4,4'-oxybis (benzoyl chloride) (OBBC) and 2.52 g (12.4 mmol) of terephthaloyl chloride (TPC) were added at room temperature, and the mixture was stirred at room temperature for 10 minutes. did. Again, 0.679 g (2.30 mmol) of OBBC and 2.52 g (12.4 mmol) of TPC were added, and the mixture was stirred at room temperature for 30 minutes. At this time, a small amount of the reaction solution was withdrawn for analysis, and the mixture was charged in methanol / water = 1/1 to obtain an intermediate polymer. To the resulting reaction solution (the reaction solution after stirring for 30 minutes), 251 g of DMAc was added, and after stirring for 5 minutes, 0.562 g (2.77 mmol) of TPC was further added, followed by stirring at room temperature for 2 hours (step (II)). ). At this time, the viscosity of the reaction solution at 25 ° C. was 16,000 cP, and the stirring state was good.
About 10 times the amount of water with respect to the mass of the reaction solution was added to obtain a white solid. The obtained solid was air-dried at room temperature for one day to obtain a polyamideimide precursor. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 765,000. The weight average molecular weight of the intermediate polymer was 173,000.
The weight-average molecular weight of the polyamide-imide precursor obtained in Example 1 is considered to be sufficiently high for the obtained polyamide-imide to have a high molecular weight.

Table 1 shows the amounts of OBBC, TPC and solvent added and the intervals (time between each addition). In Example 1, 91 mol% of the dicarboxylic acid compound with respect to the total molar amount of the dicarboxylic acid compound to be added was added twice, and then the remaining dicarboxylic acid was added. In the formula (X), t ₁ / n is 10 minutes / 2 = 5 minutes, and t ₂ is 35 minutes, which satisfies the relationship of the formula (X).

[Example 2]
A polyamideimide precursor was obtained in the same manner as in Example 1, except that the amount of DMAc charged before the raw material monomer was charged was 195 g, and the amount of DMAc added was 305 g. The viscosity at 25 ° C. of the content after the reaction was 28,000 cP, and the stirring state was good. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 865,000, and the weight average molecular weight of the intermediate polymer was 173,000.
The weight-average molecular weight of the polyamide-imide precursor obtained in Example 2 is considered to be sufficiently high for the obtained polyamide-imide to have a high molecular weight.

[Example 3]
A polyamideimide precursor was obtained in the same manner as in Example 1, except that the amount of DMAc to be additionally added was 166 g. The viscosity at 25 ° C. of the content after the reaction was 77,000 cP, and the stirring state was good. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 926,000, and the weight average molecular weight of the intermediate polymer was 185,000.
The weight-average molecular weight of the polyamide-imide precursor obtained in Example 3 is considered to be sufficiently high for the obtained polyamide-imide to have a high molecular weight.

[Comparative Example 1]
Nitrogen was passed through a 1 L separable flask equipped with a sufficiently dried stirrer and thermometer for 30 minutes or more, and the inside of the vessel was replaced with nitrogen. 500 g of DMAc was placed in a flask, 14.8 g (46.2 mmol) of TFMB and 6.13 g (13.8 mmol) of 6FDA were added at room temperature, and the mixture was stirred for 15 minutes or more, and then left for 16 hours.
Then, at room temperature, 1.358 g (4.60 mmol) of OBBC and 5.602 g (27.59 mmol) of TPC were added, and the mixture was stirred at room temperature for 2 hours and 40 minutes. At this time, the viscosity of the reaction solution at 25 ° C. was 1,000 cP, and the stirring state was good. About 10 times the amount of water was added to the mass of the reaction solution to obtain a white solid. The obtained solid was air-dried at room temperature for one day to obtain a polyamideimide precursor. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 271,000.

[Comparative Example 2]
A polyamideimide precursor was obtained in the same manner as in Comparative Example 1, except that the amount of DMAc was changed to 251 g. The viscosity at 25 ° C. of the content after the reaction was 300,000 cP, and stirring was difficult. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 536,000.

  In Examples 1 to 3 in which the solvent (DMAc) was further added in the step (II), the weight average molecular weight of the polyamide imide precursor was lower than the polyamide imide of Comparative Examples 1 and 2 in which the solvent was not added in the step (II). It was confirmed that it was significantly larger than the precursor. Therefore, the weight average molecular weight of the polyamide imide obtained by adding acetic anhydride and 4-picoline to the polyamide imide precursors of Examples 1 to 3 and reacting them is the same as that of the polyamide imide precursors of Comparative Examples 1 and 2. This is considered to be significantly larger than the polyamideimide obtained by

[Example 4]
Nitrogen was passed through a 1 L separable flask equipped with a sufficiently dried stirrer and thermometer for 30 minutes or more, and the inside of the vessel was replaced with nitrogen. 250 g of DMAc was placed in a flask, 14.6 g (45.7 mmol) of TFMB and 6.15 g (13.9 mmol) of 6FDA were added at room temperature, and the mixture was stirred for 15 minutes or more, and then left for 16 hours (step (I)).
Next, 1.36 g (4.6 mmol) of OBBC and 5.06 g (24.9 mmol) of TPC were added at room temperature, and the mixture was stirred at room temperature for 30 minutes. The operation of adding OBBC and TPC required 6 minutes. At this time, a small amount of the reaction solution was withdrawn for analysis, and the mixture was charged in methanol / water = 1/1 to obtain an intermediate polymer. 250 g of DMAc was added to the resulting reaction solution (the reaction solution after stirring for 30 minutes), and after stirring for 5 minutes, 0.562 g (2.77 mmol) of TPC was further added, followed by stirring at room temperature for 2 hours (step (II)). ). At this time, the viscosity of the reaction solution at 25 ° C. was 7,500 cP, and the stirring state was good.
At this time, a small amount of the reaction solution was withdrawn for analysis, and the solution was added to methanol / water = 1/1 to obtain a white solid. The obtained solid was air-dried at room temperature for one day to obtain a polyamideimide precursor. Subsequently, 9.9 g (97.0 mmol) of acetic anhydride and 3.0 g (32.3 mmol) of 4-picoline were added, and the mixture was stirred at room temperature for 30 minutes, heated to 70 ° C. in an oil bath, and stirred for 3 hours. (Step (III)). The obtained reaction solution was cooled to 50 ° C., to which 3 times the amount of methanol and the same amount of water with respect to the mass of the reaction solution was added, to obtain a white solid. The obtained solid was dried under reduced pressure at 60 ° C. overnight to obtain a polyamideimide resin. The weight average molecular weight (Mw) of the obtained polyamideimide precursor was 631,000, and the weight average molecular weight of the intermediate polymer was 95,000. The weight average molecular weight of the obtained polyamideimide was 401,000, which was a sufficiently high molecular weight.

Table 2 shows the amounts of OBBC, TPC and the solvent added and the intervals (time between each addition). In Example 1, 91 mol% of the dicarboxylic acid compound was added once with respect to the total molar amount of the dicarboxylic acid compound to be added, and then the remaining dicarboxylic acid was added. In the formula (X), t ₁ / n is 6 minutes / 1 = 6 minutes, and t ₂ is 35 minutes, which satisfies the relationship of the formula (X).

Claims (7)

A method for producing a polyamideimide precursor having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound,
Step (I) of producing an intermediate (A) by reacting a diamine compound and a tetracarboxylic acid compound in a solvent, and Step (II) of reacting the intermediate (A) with a dicarboxylic acid compound in a solvent Including
In the method (II), a solvent is further added.   The method according to claim 1, wherein in step (II), a solvent is further added after adding 60 to 99 mol% of the dicarboxylic acid compound based on the total molar amount of the dicarboxylic acid compound to be added.   The method according to claim 2, wherein in the step (II), a solvent is added simultaneously with or before adding the remaining dicarboxylic acid compound. In the step (II), after adding 60 to 99 mol% of the dicarboxylic acid compound with respect to the total molar amount of the dicarboxylic acid compound to be added n times, and then adding the remaining dicarboxylic acid compounds, the following formula (X)
t ₁ / n <t ₂ (X)
Wherein (X), _{t 1} represents the time up to the point of ending from the time of starting the addition of the 60 to 99 mole% of the dicarboxylic acid compound, _{t 2} is the 60 to 99 mole% of the dicarboxylic acid compound Represents the time from the end of the addition to the start of the addition of the remaining dicarboxylic acid compound, and n represents an integer of 1 to 20]
The method according to any one of claims 1 to 3, which satisfies the following relationship.   5. The method according to claim 1, wherein in the step (II), a solvent is further added after the weight average molecular weight of the polyamideimide precursor reaches 10% or more with respect to the weight average molecular weight of the obtained polyamideimide precursor. Crab method.   The method according to any one of claims 1 to 5, wherein in step (II), the substrate concentration after the addition of the solvent is 30 to 80% of the initial substrate concentration before the reaction.   A method for producing a polyamideimide, comprising a step (III) of imidizing the polyamideimide precursor according to any one of claims 1 to 6 in the presence of an imidation catalyst.