JP2011151091A - Coating liquid for forming gate insulating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gate insulating film of high electric charge mobility, which is formed by employing a simple film formation method such as spin coating or printing, and also to provide a composition for forming the film, and a good organic thin-film transistor that uses the gate insulating film. <P>SOLUTION: As a gate insulating film formation composition, an epoxy resin curing composition is used which contains a polyamide compound having a structure containing a phenolic hydroxyl group represented by a general formula (I) or (II) in a repeating unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, when manufacturing an organic thin film transistor, a gate insulating film having good charge mobility can be formed at a relatively low temperature, and a simple film forming method such as spin coating or printing can be employed. The present invention relates to an excellent coating liquid for forming a gate insulating film.

  Plastic materials such as polycarbonate and polyethylene terephthalate are used as materials for electronic substrates of flexible devices such as electronic paper, and organic thin film transistors for driving electronic paper are formed on such plastic substrates. For this, it is necessary to form a gate insulating film which has been conventionally formed at a relatively high temperature at a lower temperature, specifically at 200 ° C. or lower.

  As a general gate insulating film, a highly insulating inorganic material such as silicon carbide, silicon nitride, aluminum oxide, tantalum oxide, or titanium oxide is formed by CVD. However, the film formation by CVD requires a large-scale vacuum system, and there are problems such as an increase in manufacturing cost. In addition, since these inorganic materials are hard, they have a drawback of low flex resistance, such as being damaged by bending, and it is considered difficult to apply to flexible substrates.

On the other hand, an organic thin film transistor in which each part of a transistor is made of an organic material has attracted attention, and many researches and developments have been made in recent years. The reason why organic materials are attracting attention is that many organic materials have flexibility and many are soluble in organic solvents. This is because it is considered that the manufacturing cost can be reduced by not requiring the vacuum device that is necessary for the inorganic material.
Among them, a polyimide-based material as a material for a gate insulating film has a high withstand voltage characteristic and a low leakage current density. Therefore, an increase in electric field effect due to a thin film is expected, and a transistor has a high charge mobility. These materials are attracting attention (see Patent Document 1 and Non-Patent Document 1).

  However, since many polyimide materials require a heating step of 200 ° C. or higher for the film formation temperature, it has been difficult to apply them to plastic substrates. Patent Document 2 describes a gate insulating film coating solution containing polyimide that can be formed at 200 ° C. or lower, but a sufficiently high charge mobility is not obtained.

JP 2008-227294 A JP 2009-4394 A

Chem. Matter. 9.1299 (1997)

  Accordingly, an object of the present invention is to form a gate insulating film having a good charge mobility at a relatively low temperature in the production of an organic thin film transistor, and to provide a simple film forming method such as spin coating or printing. An object of the present invention is to provide an excellent coating solution for forming a gate insulating film that can be employed.

  Another object of the present invention is to form a gate insulating film having good charge mobility at a relatively low temperature in the production of an organic thin film transistor, and a simple film forming method such as spin coating or printing. It is an object to provide a gate insulating film formed using an excellent gate insulating film forming coating solution.

  Another object of the present invention is that a gate insulating film having good charge mobility can be formed at a relatively low temperature, and a simple film forming method such as spin coating or printing can be employed. Another object of the present invention is to provide an organic thin film transistor manufactured using an excellent coating solution for forming a gate insulating film.

  As a result of intensive studies in view of the above, the present inventors have found that an epoxy resin curable composition containing a specific polyamide compound can achieve the object, and have reached the present invention.

（式中、環Ａは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよく、Ｒは炭素原子数２〜１０のアルキレン基、炭素原子数６〜１８のシクロアルキレン基、炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。）

（式中、環Ｂは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。） That is, the present invention provides a gate insulating film comprising an epoxy resin curable composition containing a polyamide compound having a structure having a phenolic hydroxyl group represented by the following general formula (I) or (II) in a repeating unit: This is a forming coating solution.

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. Represents a group, and these groups may be substituted with a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. May be substituted.)

（式中、環Ａは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよく、Ｒは炭素原子数２〜１０のアルキレン基、炭素原子数６〜１８のシクロアルキレン基、炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。ｎは正数である。）

（式中、環Ｂは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。ｍは正数である。） Another aspect of the present invention is the coating liquid for forming a gate insulating film, wherein the polyamide compound has a structure having a phenolic hydroxyl group represented by the following general formula (III) or (IV).

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. And these groups may be substituted with a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms, n is a positive number.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. (M may be a positive number)

  Another aspect of the present invention is the coating liquid for forming a gate insulating film, wherein the ring A in the general formula (I) or (III) is a phenylene group or a naphthylene group.

  Another aspect of the present invention is the coating liquid for forming a gate insulating film, wherein R in the general formula (I) or (III) is a phenylene group or a naphthylene group.

  Another aspect of the present invention is the gate insulating film forming coating solution, further comprising an organic solvent and / or a leveling agent.

  Another aspect of the present invention is a gate insulating film formed by using the coating liquid for forming a gate insulating film at a baking temperature of 200 ° C. or lower.

  Another aspect of the present invention is an organic thin film transistor comprising the gate insulating film.

  The effect of the present invention is that when manufacturing an organic thin film transistor, a gate insulating film having good charge mobility can be formed at a relatively low temperature, and a simple film forming method such as spin coating or printing is employed. The present invention provides an excellent coating liquid for forming a gate insulating film.

  Another advantage of the present invention is that a gate insulating film having good charge mobility can be formed at a relatively low temperature in the production of an organic thin film transistor, and a simple film forming method such as spin coating or printing. The present invention provides a gate insulating film formed using an excellent coating liquid for forming a gate insulating film.

  Another advantage of the present invention is that a gate insulating film having good charge mobility can be formed at a relatively low temperature, and a simple film forming method such as spin coating or printing can be employed. Another object of the present invention is to provide an organic thin film transistor manufactured using an excellent coating solution for forming a gate insulating film.

FIG. 1 is a schematic cross-sectional view of an organic thin film transistor in which a thin film obtained from the coating solution of Examples 1 to 15 or Comparative Examples 1 to 5 is used as a gate insulating film. FIG. 2 is a graph showing the relationship between the current density (Current Density) and the voltage (Electric Field) of an organic thin film transistor in which the thin film obtained from the coating solution of Examples 1, 7 and 13 and Comparative Example 1 is a gate insulating film. is there. FIG. 3 is a graph showing the relationship between the drain current (Drain Current) and the gate voltage (Gate Voltage) of an organic thin film transistor having a thin film obtained from the coating solution of Examples 1, 7 and 13 and Comparative Example 1 as a gate insulating film. It is.

  Hereinafter, the coating liquid for forming a gate insulating film of the present invention will be described in detail.

（式中、環Ａは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよく、Ｒは炭素原子数２〜１０のアルキレン基、炭素原子数６〜１８のシクロアルキレン基、炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。）

（式中、環Ｂは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。） The polyamide compound used in the coating liquid for forming a gate insulating film of the present invention has a structure represented by the following general formula (I) or (II) in its repeating unit, and the structure is phenolic. It is characterized by having a hydroxyl group at a position adjacent to the amino group.

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. Represents a group, and these groups may be substituted with a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. May be substituted.)

  Examples of the arylene group having 6 to 18 carbon atoms represented by the ring A in the general formula (I) or the ring B in the general formula (II) include a 1,2-phenylene group, a 1,3-phenylene group, 1,4-phenylene group, 1,5-naphthylene group, 2,5-naphthylene group, anthracene-diyl, 4,4′-biphenylene group, 4,4′-p-terphenylene group, 4,4′-m -A terphenylene group, a 2-fur-1,4-orophenylene group, a 2,5-dimethyl-1,4-phenylene group and the like can be mentioned.

  Examples of the alkylidene diarylene group having 13 to 25 carbon atoms represented by the ring A in the general formula (I) or the ring B in the general formula (II) include a methylidene diphenylene group, an ethylidene diphenylene group, and a propylidene group. Examples thereof include dendiphenylene group, isopropylidene diphenylene group, hexafluoroisopropylidene diphenylene group, propylidene-3,3 ′, 5,5′-tetrafluorodiphenylene group, and fluorene-9-ylidene diphenylene group.

  Examples of the alkylene group having 2 to 10 carbon atoms represented by R in the general formula (I) include ethylene, propylene, trimethylene, tetramethylene, 2,2-dimethyltrimethylene, hexamethylene, octamethylene, decamethylene and the like. Can be mentioned.

  Examples of the cycloalkylene group having 6 to 18 carbon atoms represented by R in the general formula (I) include divalent groups such as cyclohexane, cycloheptane, cyclooctane, bicyclohexane, and dicyclohexane.

  Examples of the arylene group having 6 to 18 carbon atoms represented by R in the general formula (I) include the same groups as those in the ring A.

  Examples of the alkylidene diaryl group having 13 to 25 carbon atoms represented by R in the general formula (I) include the same groups as those in the ring A.

（式中、環Ａ及びＲは、前記一般式（Ｉ）と同様である。） The structure of the polyamide compound of the general formula (I) used in the coating liquid for forming a gate insulating film according to the present invention includes a phenolic hydroxyl group and an amide group adjacent to the phenolic hydroxyl group, which are dehydrated and cyclized. The structure of general formula (VI) may be included.

(In the formula, the rings A and R are the same as those in the general formula (I).)

（式中、環Ａは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよく、Ｒは炭素原子数２〜１０のアルキレン基、炭素原子数６〜１８のシクロアルキレン基、炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。ｎは正数である。）

（式中、環Ｂは炭素原子数６〜１８のアリーレン基又は炭素原子数１３〜２５のアルキリデンジアリーレン基を表し、これらの基はハロゲン原子、水酸基又は炭素原子数１〜４のアルキル基で置換されていてもよい。ｍは正数である。） The polyamide compound used in the coating liquid for forming a gate insulating film of the present invention is contained in a repeating unit from the viewpoint of physical properties (high glass transition temperature, low linear expansion coefficient, tensile strength, elongation, flexibility) of the cured product. Those having a structure of the following general formula (III) or the following general formula (IV) including those having only the structure of the general formula (I) or (II) are preferable.

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. And these groups may be substituted with a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms, n is a positive number.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. (M may be a positive number)

  Examples of the arylene group having 6 to 18 carbon atoms represented by the ring A in the general formula (III) include the same groups as those in the general formula (I).

  Examples of the alkylidene diarylene group having 13 to 25 carbon atoms represented by ring A in the general formula (III) include the same groups as those in the general formula (I).

  Examples of the alkylene group having 2 to 10 carbon atoms represented by R in the general formula (III) include the same groups as those in the general formula (I).

  Examples of the cycloalkylene group having 6 to 18 carbon atoms represented by R in the general formula (III) include the same groups as those in the general formula (I).

  Examples of the arylene group having 6 to 18 carbon atoms represented by R in the general formula (III) include the same groups as those in the general formula (I).

  Examples of the alkylidene diaryl group having 13 to 25 carbon atoms represented by R in the general formula (III) include the same groups as those in the general formula (I).

  Moreover, as n in the said general formula (III), what is 2-100 is preferable from the point of the solubility after a solvent, an epoxy resin, and another compound, and the characteristic after hardening.

  Examples of the arylene group having 6 to 18 carbon atoms represented by ring B in the general formula (IV) include the same groups as those in the general formula (II).

  Examples of the alkylidene diarylene group having 13 to 25 carbon atoms represented by ring B in the general formula (IV) include the same groups as those in the general formula (II).

  Moreover, as m in the said general formula (IV), what is 2-100 is preferable from the point of the characteristic after a solubility with a solvent, an epoxy resin, and another compound, and hardening.

  The polyamide compound used in the coating liquid for forming a gate insulating film of the present invention is preferably a compound in which the rings A and / or R in the general formula (I) or the general formula (III) are a phenylene group or a naphthylene group.

  As a more specific structure of the polyamide compound used in the coating liquid for forming a gate insulating film of the present invention, for example, the following No. 1-No. 11 structures are mentioned. However, the present invention is not limited by the following structure.

  The polyamide compound used in the coating liquid for forming a gate insulating film of the present invention can be obtained from a phenolic hydroxyl group-containing aromatic diamine having a phenolic hydroxyl group at a position adjacent to an amino group. That is, the polyamide compound is composed of a phenolic hydroxyl group-containing aromatic diamine having a phenolic hydroxyl group adjacent to the amino group and dicarboxylic acids (various aromatic dicarboxylic acids, aliphatic dicarboxylic acids, etc.) as raw materials. This is a polyamide compound. The number of phenolic hydroxyl groups attached to the position adjacent to the amino group is not particularly limited, and is, for example, 1 to 4 per molecule of the aromatic diamine as a raw material. Of course, this polyamide compound may be made from diamine compounds (various aromatic diamines, aliphatic diamines, etc.) other than diamines having phenolic hydroxyl groups at positions adjacent to amino groups as raw materials, and phenolic hydroxyl groups. You may use further dicarboxylic acid to contain.

Examples of the phenolic hydroxyl group-containing aromatic diamine having the phenolic hydroxyl group adjacent to the amino group include m-phenylenediamine, p-phenylenediamine, m-tolylenediamine, and 4,4′-diaminodiphenyl ether. 3,3′-dimethyl-4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl thioether, 3,3′-dimethyl-4,4′-diaminodiphenyl thioether, 3, 3,3′-diethoxy-4,4′-diaminodiphenylthioether, 3,3′-diaminodiphenylthioether, 4,4′-diaminobenzophenone, 3,3′-dimethyl-4,4′-diaminobenzophenone, 3,3 '-Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3, '-Diaminodiphenylmethane, 3,3'-dimethoxy-4,4'-diaminodiphenylthioether, 2,2'-bis (3-aminophenyl) propane, 2,2'-bis (4-aminophenyl) propane, 4 , 4′-diaminodiphenylsulfoxide, 4,4′-diaminodiphenylsulfone, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 3,3′-diaminobiphenyl, p- Xylylenediamine, m-xylylenediamine, o-xylylenediamine, 2,2′-bis (3-aminophenoxyphenyl) propane, 2,2′-bis (4-aminophenoxyphenyl) propane, 1,3- Bis (4-aminophenoxyphenyl) benzene, 1,3′-bis (3-aminophenoxyphenyl) propane, bis (4-a No-3-methylphenyl) methane, bis (4-amino-3,5-dimethylphenyl) methane, bis (4-amino-3-ethylphenyl) methane, bis (4-amino-3,5-diethylphenyl) Methane, bis (4-amino-3-propylphenyl) methane, bis (4-amino-3,5-dipropylphenyl) methane, 2,2′-bis (3-aminophenyl) hexafluoropropane, 2,2 Examples include aromatic diamines such as' -bis (4-aminophenyl) hexafluoropropane having 1 to 4 hydroxyl groups bonded to the position adjacent to the amino group.
However, it is not limited to these. These may be used alone or in combination of two or more, or may be used in combination with an aromatic diamine to which no hydroxyl group is bonded. Examples of the aromatic diamine to which no hydroxyl group is bonded include those described above.

  Examples of dicarboxylic acids having a phenolic hydroxyl group at a position adjacent to an amino group and reacting with a phenolic hydroxyl group-containing aromatic diamine to constitute the polyamide compound of the present invention include, for example, phthalic acid, isophthalic acid, Terephthalic acid, 4,4'-oxydibenzoic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-, methylene dibenzoic acid, 4,4'-methylene dibenzoic acid, 4,4'-thiodi Benzoic acid, 3,3′-carbonyldibenzoic acid, 4,4 ′;-carbonyldibenzoic acid, 4,4′-sulfonyldibenzoic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-naphthalenedicarboxylic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyisophthalic acid Examples include taric acid, 3-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 2,2′-bis (3-carboxyphenyl) hexafluoropropane, 2,2′-bis (4-carboxyphenyl) hexafluoropropane, and the like. However, it is not limited to these. Moreover, you may use these 1 type or in mixture of 2 or more types.

  The coating liquid for forming a gate insulating film of the present invention is an epoxy resin curable composition containing the polyamide compound.

  The epoxy resin used in the epoxy resin curable composition is not particularly limited, and known aromatic epoxy compounds, alicyclic epoxy compounds, aliphatic epoxy compounds, and the like are used.

  Examples of the aromatic epoxy compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4′-dihydroxybiphenyl, novolac, tetrabromobisphenol A, 2,2-bis (4-hydroxyphenyl) -1,1. , 1,3,3,3-hexafluoropropane and the like glycidyl ether compounds of polyhydric phenols.

  Examples of the alicyclic epoxy compound include cyclohexene oxide and cyclopentene oxide obtained by epoxidizing a polyglycidyl ether of a polyhydric alcohol having at least one alicyclic ring or a cyclohexene or cyclopentene ring-containing compound with an oxidizing agent. Containing compounds. For example, hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 3,4-epoxy-1-methylcyclohexyl-3,4-epoxy-1-methylhexanecarboxylate 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-3-methylcyclohexylmethyl-3,4-epoxy-3-methylcyclohexanecarboxy Rate, 3,4-epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, methylenebis (3,4-epoxycyclohexane 2,2-bis (3,4-epoxycyclohexyl) propane, dicyclopentadiene diepoxide, ethylene bis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2 epoxyhexahydrophthalate -Ethylhexyl etc. are mentioned.

  Examples of the aliphatic epoxy compounds include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers synthesized by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate, glycidyl Examples thereof include copolymers synthesized by vinyl polymerization of acrylate or glycidyl methacrylate and other vinyl monomers. As typical compounds, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, tetraglycidyl ether of sorbitol, dipentaerythritol One or more kinds of glycidyl ethers of polyhydric alcohols such as hexaglycidyl ether, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, and aliphatic polyhydric alcohols such as propylene glycol, trimethylolpropane and glycerin Polyglycidyl ether of polyether polyol obtained by adding alkylene oxide, diglycidyl ester of aliphatic long chain dibasic acid That. In addition, monoglycidyl ethers of higher aliphatic alcohols, phenols, cresols, butylphenols, monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to these, glycidyl esters of higher fatty acids, epoxidized soybean oil, epoxy Examples include octyl stearate, butyl epoxy stearate, and epoxidized polybutadiene.

  In this epoxy resin curable composition, the polyamide compound acts as a curing agent for the epoxy resin. The amount of the polyamide compound (curing agent) used in the epoxy resin curable composition is not particularly limited, and usually the ratio of the total number of epoxy moles of the epoxy compound to the number of functional groups of the curing agent is 0.9 / 1.0. Although it is -1.0 / 0.9, Preferably, the usage-amount of an epoxy compound is 10-80 weight% in an epoxy resin curable composition, and the usage-amount of a hardening | curing agent is 5-90 in an epoxy resin curable composition. From the range of wt%, it is selected so as to satisfy the above ratio.

  In addition, a fluorine-substituted curing agent is preferable because it becomes an epoxy resin having a low water absorption rate. However, a fluorine-substituted compound is generally expensive and is appropriately selected depending on applications including other characteristic values.

  Furthermore, an epoxy resin curing agent other than the polyamide compound can be used for the epoxy resin curable composition. It can be expected to control the viscosity and curing characteristics of the curable composition obtained by using in combination with other curing agents, and the physical properties after curing. Examples of other curing agents include latent curing agents, polyamine compounds, polyphenol compounds, and the like. In order to exert the effect of using these other curing agents in combination without inhibiting the effects of the present invention, the total curing agent is preferably 0.1 to 40% by weight, more preferably 0.1 to 10% by weight. It is used so that

  Examples of the latent curing agent include dicyandiamide, hydrazide, imidazole compound, amine adduct, sulfonium salt, onium salt, ketimine, acid anhydride, and tertiary amine. These latent curing agents are preferable because they give a one-component curable composition and are easy to handle.

  Examples of the imidazole compound include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, and 1-benzyl. 2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6 (2′-methylimidazole (1 ′ )) Ethyl-s-triazine, 2,4-diamino-6 (2′-undecylimidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-ethyl, 4-methylimidazole) (1 ′)) Ethyl-s-triazine, 2,4-diamino 6 (2′-methylimidazole (1 ′)) ethyl-s-triazine isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2: 3 adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3 , 5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5-dicyanoethoxymethylimidazole imidazoles, and imidazoles and phthalic acid And salts with polyvalent carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, maleic acid and oxalic acid.

  Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, 2 , 2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride and the like.

  Examples of the polyamine compound include aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine, mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, bis (aminomethyl) cyclohexane, 3, Aliphatic polyamines such as 9-bis (3-aminopropyl) 2,4,8,10-tetraoxaspiro [5,5] undecane, aliphatic amines having an aromatic ring such as m-xylenediamine, m-phenylene Diamine, 2,2-bis (4-aminophenyl) propane, diaminodiphenylmethane, diaminodiphenylsulfone, α, α-bis (4-aminophenyl) -p-diisopropylbenzene, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexaful Aromatic polyamines such as olopropane can be mentioned.

  Examples of the polyphenol compound include phenol novolak, o-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, terpene diphenol, terpene dicatechol, 1,1,3-tris (3-tert-butyl-4- Hydroxy-6-methylphenyl) butane, butylidenebis (3-tert-butyl-4-hydroxy-6-methylphenyl), 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3 -Hexafluoropropane and the like.

  The epoxy resin curable composition of the coating liquid for forming a gate insulating film according to the present invention described above contains an organic solvent and a leveling agent in addition to the epoxy resin and the curing agent. It is preferable from the viewpoint of application by law.

  As this organic solvent, the epoxy resin and the curing agent can be dissolved to have a viscosity (known viscosity) suitable for application by a spin coating method or a printing method (referred to as a diluent in this sense). Can be used without particular limitation as long as it does not inhibit the effects of the present invention. For example, alcohols, ethers, lactams, imidazoles, acetals, ketones, esters Organic alcohols such as alcohols, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, ester ethers, and aromatic solvents. Specific preferred examples include: N-methylpyrrolidone, propylene glycol monomethyl ether, 2-ethyl-4-methylimidazole, etc. Bets can be, in particular propylene glycol monomethyl ether. The amount of the organic solvent used is arbitrary, and since it is sufficient to make it a necessary and sufficient amount necessary for obtaining a known viscosity suitable for application by the spin coating method or the printing method, it cannot be generally stated. The total amount of the epoxy resin and the curing agent may be 50 to 5000 parts by mass, preferably 200 to 1000 parts by mass with respect to 100 parts by mass. For example, in the case of propylene glycol monomethyl ether, 100 to 2000 parts by mass, preferably 300 to 600 parts by mass may be used with respect to 100 parts by mass of the total amount of the epoxy resin and the curing agent. Other solvents may be appropriately used so as to have the same viscosity as this.

  The leveling agent is used for the purpose of smoothing a viscous liquid surface, and can be dissolved in the epoxy resin curable composition and does not inhibit the effect of the present invention. Such leveling agents can also be used, but leveling agents such as fluorosurfactants are preferred, and commercially available leveling agents can also be used. For example, F-470 manufactured by DIC Corporation ( Fluorine-based surfactants) and leveling agents having the same properties as those described above can be exemplified as preferable examples. The amount of the leveling agent used is arbitrary, and since it may be a necessary and sufficient amount required for the well-known smoothness suitable for application in the spin coating method or the printing method, it cannot be generally stated, Usually, the epoxy resin and the curing agent may be used in an amount of 0.001 to 10 parts by mass, preferably 0.005 to 5 parts by mass, with respect to 100 parts by mass of the total amount. As an example, if F-470 manufactured by DIC Corporation is used, 0.1 to 5 parts by mass, preferably 0.2 to 1 part by mass is used with respect to 100 parts by mass of the total amount of epoxy resin and curing agent do it.

Hereinafter, the gate insulating film and the organic thin film transistor of the present invention will be described in detail.
The gate insulating film of the present invention is formed by using the coating liquid for forming a gate insulating film of the present invention at a baking temperature of 200 ° C. or lower. Here, “use the gate insulating film forming coating solution of the present invention” means that the gate insulating film forming coating solution of the present invention is applied to the gate electrode on the substrate.

  In the gate insulating film of the present invention, the substrate on which the coating liquid for forming the gate insulating film of the present invention is applied is arbitrary and may be appropriately selected depending on the specifications of the organic thin film transistor to be obtained. For example, a plastic material such as polycarbonate or polyethylene terephthalate is suitable.

  Examples of the gate electrode include metals such as gold, silver, copper, aluminum, and calcium; inorganic materials such as carbon black, fullerenes, and carbon nanotubes; and polythiophene, polyaniline, polypyrrole, polyfluorene, and the like. And organic π-conjugated polymers such as derivatives.

  The gate insulating film forming coating solution of the present invention can be applied by dipping, spin coating, printing, roll coating, ink jet, spraying, brush coating, or the like.

  Although the baking method after apply | coating the coating liquid for gate insulating film formation of this invention to a board | substrate (gate electrode on a board | substrate) is not specifically limited, For example, in a suitable atmosphere using a hotplate or oven, That is, it can be carried out in the presence of an inert gas such as air or nitrogen, or in a vacuum (30 Pa or less, preferably 10 Pa or less), and the temperature is 200 ° C. or less, preferably about 170 to 190 ° C.

  By the above baking, the solvent evaporates and the epoxy resin contained in the coating liquid can be cured, and the gate insulating film of the present invention formed from the coating liquid for forming a gate insulating film of the present invention is formed. Can do.

  If the gate insulating film of the present invention is too thin, dielectric breakdown occurs in a low electric field and does not operate as a transistor, and if it is too thick, a high voltage is required to operate the transistor. The film thickness is preferably 300 to 1500 nm, more preferably 500 to 800 nm.

  The organic thin film transistor of the present invention has the same configuration as a conventionally known or well-known organic thin film transistor except that it has the gate insulating film of the present invention as a gate insulating film, and is not particularly limited.

  The present invention will be further described with reference to examples. However, the present invention is not limited by the following examples.

[Synthesis Example 1] Synthesis of Example Polymer 1 (Polyamide having No. 1 Structure) 2.49 g (0.045 mol) of 2,4-diaminophenol was added to 40 g of N-methylpyrrolidone (hereinafter NMP) and 15.33 g of pyridine A solution prepared by dissolving 10.05 g (0.0495 mol) of isophthaloyl chloride in 40 g of NMP was added dropwise at -15 to 0 ° C. The reaction was continued for 2 hours while maintaining -15 to 0 ° C., and further for 2 hours at room temperature. This reaction solution was reprecipitated with about 2 liters of ion exchange water, filtered, and dried under reduced pressure at 150 ° C. for 3 hours to obtain 15 g (yield 79.1%) of a white powder (Example polymer 1). The obtained compound was confirmed to be an amide bond by an infrared absorption spectrum and confirmed to be a polymer having a weight average molecular weight of 7000 by gel permeation chromatography. According to the analysis, the viscosity was 270 cps (25 ° C., 30 wt% NMP solution), and the OH equivalent was 289 g / eq.

[Synthesis Examples 2 to 17]
The following implementation polymers 2 to 17 were synthesized in the same manner as in Synthesis Example 1. The weight average molecular weight, viscosity, and OH equivalent of the resulting polymer are shown below.

[Examples 1-15, Comparative Examples 1-5]
A gate insulating film-forming coating solution for comparison with the gate insulating film-forming coating solution of the present invention was prepared by the formulation shown in Table 1 using the implementation polymer obtained in the synthesis example. In order to evaluate the characteristics of the prepared coating liquid for forming a gate insulating film as a gate insulating film, an organic thin film transistor for evaluation (TFT) as shown in FIG. 1 was manufactured as follows.
That is, a bottom gate / top contact type element is formed by vapor deposition on a glass substrate 1 with a Cr film (a lead electrode having a width of 2 mm, a thickness of about 100 nm) as a gate electrode 3, and each gate insulating film is formed thereon. The coating liquid for coating was applied on the substrate at 3000 rpm × 120 seconds with a spin coater, and the solvent was dried by heating at 100 ° C. × 10 minutes, followed by heat treatment at 180 ° C. × 90 minutes to form the gate insulating film 2 ( 700 nm thick), and spin coating is performed thereon using poly- (3-hexyl) thiophene as the organic semiconductor layer 4 and xylene as a solvent, and the source electrode (5, 6) and the drain electrode (5 6) (Channel length 100 μm × width 2 mm) was laminated by a gold vapor deposition method (thickness 30 nm) to produce an organic thin film transistor for evaluation.

上記式において、Ｗはトランジスタのチャネル幅、Ｌはトランジスタのチャネル長、Ｃはゲート絶縁膜の静電容量、Ｖ_Tはトランジスタの閾値電圧、μは電荷移動度である。
表1において、実施ポリマー、エポキシ樹脂、ＰＧＭ及び界面活性剤の数字は質量部である。電流密度は、Ｉ-Ｖ測定の結果において、電界強度が０．５ＭＶ／ｃｍのときの値である。静電容量は、ゲート絶縁膜の比誘電率と膜厚から求めた。また表１中の記号は以下の通りである。 The organic thin film transistor was measured for transport characteristics using a semiconductor parameter analyzer SCS4200 manufactured by Keithley, and the charge mobility μ was calculated from the saturation region. More specifically, the vertical axis of the square root of the absolute value of the drain current I _D in the saturation region represented by the following formula, was calculated from the slope of the graph when plotted the gate voltage V _G on the horizontal axis. The measurement was performed in a light-shielded state under a nitrogen gas atmosphere. The results are shown in Table 1.

In the above equation, W is the channel width of the transistor, L is the channel length of the transistor, C is the capacitance of the gate insulating film, V _T is the threshold voltage of the transistor, and μ is the charge mobility.
In Table 1, the numbers of the implementation polymer, epoxy resin, PGM and surfactant are parts by mass. The current density is a value when the electric field strength is 0.5 MV / cm in the result of the IV measurement. The capacitance was obtained from the relative dielectric constant and film thickness of the gate insulating film. The symbols in Table 1 are as follows.

EP-1: Bisphenol A type epoxy resin manufactured by ADEKA Corporation, trade name EP-4100
EP-2: 4,4′-biphenyl epoxy resin manufactured by Japan Epoxy Resin Co., Ltd., trade name YX-4000H
EP-3: Naphthalene type epoxy resin manufactured by DIC Corporation, trade name HP-4032
EP-4: Phenol novolac epoxy resin manufactured by DIC Corporation, trade name N-665
EP-5: ADEKA Corporation, alicyclic epoxy resin, trade name EP-4088
PGM: Propylene glycol monomethyl ether surfactant: manufactured by DIC Corporation, trade name F-470

From Table 1 above, the gate insulating film formed from the coating liquid for forming a gate insulating film of the present invention has a current density of only 10 ⁻¹⁰ A / cm ² even when a high voltage is applied, and is very excellent. In addition, it showed good charge mobility as compared with the comparative gate insulating film.

1: Glass substrate 2: Gate insulating film 3: Gate electrode (Cr vapor deposition film)
4: Organic semiconductor layers 5, 6: Source and drain electrodes (Au vapor deposition film)

Claims (7)

The coating liquid for gate insulating film formation which consists of an epoxy resin curable composition containing the polyamide compound which has a structure which has the phenolic hydroxyl group represented by the following general formula (I) or (II) in a repeating unit.

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. Represents a group, and these groups may be substituted with a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. May be substituted.) The coating liquid for forming a gate insulating film according to claim 1, wherein the polyamide compound has a structure having a phenolic hydroxyl group represented by the following general formula (III) or (IV).

(In the formula, ring A represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms. R may be substituted, and R is an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an alkylidene diarylene having 13 to 25 carbon atoms. And these groups may be substituted with a halogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms, n is a positive number.)

(In the formula, ring B represents an arylene group having 6 to 18 carbon atoms or an alkylidene diarylene group having 13 to 25 carbon atoms, and these groups are a halogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms. (M may be a positive number)   The coating liquid for forming a gate insulating film according to claim 1 or 2, wherein the ring A in the general formula (I) or (III) is a phenylene group or a naphthylene group.   The coating liquid for forming a gate insulating film according to claim 1, wherein R in the general formula (I) or (III) is a phenylene group or a naphthylene group.   Furthermore, the coating liquid for gate insulating film formation in any one of Claims 1-4 containing an organic solvent and / or a leveling agent.   A gate insulating film formed by using the coating liquid for forming a gate insulating film according to claim 1 at a baking temperature of 200 ° C. or lower.   An organic thin film transistor comprising the gate insulating film according to claim 6.

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