JP2012224755A - Highly transparent polyimide precursor and resin composition using the same, polyimide molded article and method for producing the molding, plastic substrate, protective film, and electronic component and display device having the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition which has sufficient transparency even if it is subjected to a heating treatment at a high temperature of 300°C or more and has excellent chemical resistance, to provide a polyimide molded article using the resin composition, and to provide a method for producing the polyimide molded article, or the like.SOLUTION: A polyimide precursor has a repeating unit represented by general formula (I). The resin composition includes the polyimide precursor. The polyimide molded article is obtained by heating the resin composition. A plastic substrate is formed from the polyimide molding. A protective film is formed from the polyimide molding. An electronic component and a display device each have the protective film. In the formula (I), X represents a diamine residue having ether bond and biphenyl skeleton.

Description

  The present invention relates to a polyimide precursor excellent in transparency, chemical resistance, heat resistance and mechanical properties, a resin composition containing the polyimide precursor, and a polyimide molded body formed by molding the resin composition. The present invention also relates to a plastic substrate and a protective film made of the molded body, or an electric / electronic component including the substrate and the protective film, and a method for producing the polyimide molded body.

  In general, a polyimide resin has not only high heat resistance, but also electrical characteristics excellent in insulation, and mechanical strength such as wear resistance and dimensional stability. Since it has such characteristics, it is widely used in the electric and electronic industries such as a base film of a flexible printed circuit board. In recent years, in the field of display devices, replacement of a substrate glass or a cover glass with a plastic substrate has been studied in order to improve breakage resistance, reduce the weight, and reduce the thickness. A display device includes a liquid crystal display, an organic electroluminescence display, electronic paper, and the like. In particular, there is a strong demand for a plastic substrate in a display device for mobile information communication equipment such as a portable information terminal such as a mobile phone, an electronic notebook, or a laptop personal computer. Furthermore, in addition to heat resistance and mechanical properties, there is a strong demand for the development of a resin material that is excellent in transparency from the viewpoint of realizing high visibility and application to a transmissive display.

  However, in general, a polyimide resin is colored yellowish brown due to intramolecular conjugation and formation of a charge transfer complex. As a solution to this, there is a method of inhibiting the formation of a charge transfer complex and introducing transparency by introducing fluorine into the polyimide resin, imparting flexibility to the main chain, introducing bulky side chains, etc. It has been proposed (Non-Patent Document 1). In addition, a method of expressing transparency by using a semi-alicyclic or fully alicyclic polyimide resin that does not form a charge transfer complex has been proposed (Patent Documents 1 to 3).

JP 2002-348374 A JP 2005-015629 A JP 2009-286706 A

Polymer (USA), vol. 47, p. 2337-2348, 2006

  On the other hand, a plastic substrate used in a display device is required to have resistance in a resist process. In the resist process, an organic solvent (resist stripper) is often used when removing the resist, and resistance to these chemicals is required. However, polyimide resins obtained from fluorinated monomers and alicyclic monomers as in Patent Documents 1 to 3 have a problem that cracks occur in the polyimide resin during the resist process.

  Therefore, an object of the present invention is to provide a polyimide precursor that has sufficient transparency even when heat-treated at a high temperature of 300 ° C. or more and is excellent in chemical resistance, and a resin composition containing the same.

  In addition, the present invention provides a molded body obtained by heat-treating the resin composition, a plastic substrate and a protective film made of the molded body, an electric / electronic component including the substrate and the protective film, and a method for producing the same. To do.

  The present invention provides (a) a polyimide precursor having a repeating unit represented by the general formula (I).

（一般式（Ｉ）中、Ｘはエーテル結合とビフェニル骨格を有するジアミン残基を示す）
また、本発明のポリイミド前駆体は、一般式（Ｉ）で示される繰り返し単位を有するポリイミド前駆体が、一般式（II）で示される繰り返し単位を有することが好ましい。

(In the general formula (I), X represents a diamine residue having an ether bond and a biphenyl skeleton)
In the polyimide precursor of the present invention, the polyimide precursor having a repeating unit represented by the general formula (I) preferably has a repeating unit represented by the general formula (II).

（一般式（IＩ）中、ｎは、１〜３の整数を示す）

(In general formula (II), n represents an integer of 1 to 3)

  Moreover, this invention provides the resin composition containing the said polyimide precursor. Further, the resin composition of the present invention preferably contains (b) an organic solvent.

  Furthermore, this invention provides the polyimide molded body obtained by heating the said resin composition. Moreover, the plastic substrate or protective film which consists of said polyimide molded object is provided. Furthermore, an electronic component and a display device having the plastic substrate or the protective film are provided. Moreover, the manufacturing method of the polyimide molded body which includes the process of apply | coating and drying the said resin composition on a base material and forming a resin film, and the process of heat-processing the resin film after the said drying is provided.

  According to the present invention, it is possible to provide a resin composition that has sufficient transparency even after heat treatment at 300 ° C. or more and is excellent in chemical resistance. Moreover, the resin composition which provides the polyimide molded body which has the heat resistance and mechanical strength which are the original characteristics of a polyimide can be provided. The transparent polyimide molded body of the present invention is colorless and highly transparent, exhibits high heat resistance, and is excellent in chemical resistance. Therefore, it can be suitably used as a flexible display substrate or a protective film. It is possible to provide electrical / electronic components (electrical insulating films and liquid crystal displays in various electronic devices, organic electroluminescence displays, electronic paper, solar cells, etc.) provided with the flexible display substrate or protective film.

  Hereinafter, embodiments of an electronic component having a polyimide precursor, a resin composition, a polyimide molded body, a manufacturing method thereof, and a protective film according to the present invention will be described in detail. In addition, this invention is not limited by this embodiment.

[(A) Polyimide precursor]
The polyimide precursor of the present invention has (a) a repeating unit represented by the general formula (I).

（一般式（Ｉ）中、Ｘはエーテル結合とビフェニル骨格を有するジアミン残基を示す）

(In the general formula (I), X represents a diamine residue having an ether bond and a biphenyl skeleton)

  Moreover, it is preferable that a polyimide precursor has a repeating unit shown by general formula (II) from a viewpoint of improving a chemical | medical solution tolerance more.

（一般式（IＩ）中、ｎは、１〜３の整数を示す）

(In general formula (II), n represents an integer of 1 to 3)

  Generally, a polyimide precursor is a polyamic acid obtained by polymerizing at least one tetracarboxylic acid selected from the group consisting of tetracarboxylic dianhydrides and derivatives thereof and at least one diamine.

  Examples of the tetracarboxylic acids used for the synthesis of the polyimide precursor (a) of the present invention include 1,2,4,5-cyclohexanetetracarboxylic acid, and the three-dimensional structure is (1R, 2S, 4S, 5R) -cyclohexane. Preferred is tetracarboxylic acid (HS) or (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic acid (HH). From the viewpoint of reactivity during synthesis, it is preferable to use (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic acid (HH).

  Examples of diamines used for the synthesis of the polyimide precursor of the present invention include aromatic diamines. Specifically, it is a diamine having an ether bond and a biphenyl skeleton, and examples thereof include the following compounds.

（ｎは、１〜３の整数を示す）
入手のしやすさ及び薬液耐性をより向上させる観点から、４，４′−ビス（４−アミノフェノキシ）ビフェニルを用いることが好ましい。

(N represents an integer of 1 to 3)
It is preferable to use 4,4′-bis (4-aminophenoxy) biphenyl from the viewpoint of improving availability and chemical resistance.

[(A) Polyimide precursor synthesis]
The polyimide precursor which is the component (a) of the present invention can be synthesized by a conventionally known polyamic acid synthesis method. For example, after dissolving a predetermined amount of diamines in a solvent, tetracarboxylic dianhydride obtained by subjecting the resulting diamine solution to dehydration ring closure by heating tetracarboxylic acid with a dryer at 160 ° C. for 24 hours. Add a predetermined amount and stir. When dissolving each monomer component, you may heat as needed. The reaction temperature is preferably −30 to 200 ° C., more preferably 20 to 180 ° C., and further preferably 30 to 100 ° C. Stirring is continued as it is at room temperature (20 to 25 ° C.) or at an appropriate reaction temperature, and the end point of the reaction is determined when the viscosity of the polyamic acid becomes constant. The viscosity was measured at 25 ° C. using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.). Although the said reaction is based also on the kind of tetracarboxylic dianhydride and diamine to be used, it can be completed normally in 3 to 100 hours.

  The polyamic acid component (hereinafter referred to as solute) is 5 to 60% by mass from the viewpoint of the film-forming property with respect to the total amount of the solution (hereinafter referred to as polyamic acid solution) containing the obtained polyamic acid (polyimide precursor). It is preferable that it is 10-50 mass%, and it is especially preferable that it is 10-40 mass%. The ratio of the solute (resin non-volatile content) in the polyamic acid solution is determined by taking the polyamic acid solution into a metal petri dish having a known mass (about 1 g as a guide) and the mass (mass of the metal petri dish and polyamic acid, hereinafter heating) Measure the mass after heating for 2 hours on a hot plate at 200 ° C. (the mass of the metal petri dish and solute, hereinafter referred to as the mass after heating). , (Mass after heating−mass of metal petri dish) ÷ (mass before heating−mass of metal petri dish) × 100.

  The solvent used for synthesizing the polyamic acid of the present invention is not particularly limited as long as it is a solvent that can dissolve diamines and tetracarboxylic acids and the resulting polyamic acid. Specific examples of such solvents include aprotic solvents, phenol solvents, ethers and glycol solvents. Specifically, as the aprotic solvent, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethyl Amide solvents such as urea; Lactone solvents such as γ-butyrolactone and γ-valerolactone; Phosphorus amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide; dimethyl sulfone, dimethyl sulfoxide, sulfolane, etc. Sulfur-containing solvents; ketone solvents such as cyclohexanone and methylcyclohexanone; tertiary amine solvents such as picoline and pyridine; ester solvents such as acetic acid (2-methoxy-1-methylethyl). Phenol solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol and the like can be mentioned. Examples of ether and glycol solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and bis [2- (2-methoxyethoxy) ethyl] ether. , Tetrahydrofuran, 1,4-dioxane and the like. Of these, N-methyl-2-pyrrolidone is preferable from the viewpoints of solubility and film-forming properties. These reaction solvents may be used alone or in combination of two or more.

  The molecular weight of the polyamic acid (polyimide precursor) of the present invention is preferably 10,000 to 500,000 in terms of weight average molecular weight, more preferably 10,000 to 300,000, and even more preferably 20,000 to 300,000. Here, a weight average molecular weight can be calculated | required by standard polystyrene conversion using the gel permeation chromatography method (GPC, apparatus is Hitachi Ltd. make, a column is Hitachi Chemical Co., Ltd. gel pack). If the molecular weight is less than 10,000, it is difficult to form a film by thermoforming, and even if the film can be formed, the mechanical properties are poor. When the molecular weight is larger than 500,000, it is difficult to control the molecular weight during the synthesis of polyamic acid, and it becomes difficult to obtain a resin composition having an appropriate viscosity.

  The solution viscosity of the polyamic acid (polyimide precursor) of the present invention is preferably 500 to 200,000 mPa · s at 25 ° C, more preferably 2000 to 100,000 mPa · s, and more preferably 5000 to 30000 mPa · s. Further preferred. Here, the viscosity was measured at 25 ° C. using an E-type viscometer (VISCONIC EHD manufactured by Toki Sangyo Co., Ltd.). When the viscosity is lower than 500 mPa · s, it is difficult to apply the film during film formation, and when it is higher than 200000 mPa · s, there is a problem that stirring during synthesis becomes difficult. However, even when the high viscosity shown here is obtained during the synthesis of the polyamic acid, it is possible to obtain a polyamic acid having a good handleability by adding a solvent after the reaction and stirring.

[(B) Organic solvent]
The resin composition of the present invention preferably uses (b) an organic solvent as necessary. The (b) organic solvent is not particularly limited as long as it can dissolve the polyimide precursor (polyamide acid) of the present invention. Such a solvent is used at the time of synthesizing the (a) polyimide precursor (polyamide acid). What was described as a solvent which can be used can be used. (B) The organic solvent may be the same as or different from the reaction solvent used in the synthesis of (a) polyamic acid. (B) Content of a component is adjusted and added so that the viscosity in 25 degreeC of a resin composition may be set to 0.5 Pa.s-100 Pa.s.

  Moreover, 60-210 degreeC is preferable, the boiling point in the normal pressure of (b) organic solvent has more preferable 100-205 degreeC, and 140-180 degreeC is further more preferable. If the boiling point is higher than 210 ° C., a drying process is required for a long time. If the boiling point is lower than 60 ° C., the film surface may be roughened in the drying process, or bubbles may enter the film and a clean film may not be obtained.

[Other ingredients]
The resin composition according to the present invention may contain (1) an adhesion-imparting agent, (2) a surfactant or a leveling agent, (3) a solvent, etc., in addition to the components (a) and (b). good.

[Other components: (1) Adhesiveness imparting agent]
The resin composition of the present invention may contain (1) an adhesion-imparting agent such as an organic silane compound and an aluminum chelate compound in order to enhance the adhesion of the cured film to the substrate.

  Examples of the organic silane compound include vinyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, urea propyltriethoxysilane, methylphenylsilanediol, ethylphenylsilanediol, n- Propylphenylsilanediol, isopropylphenylsilanediol, n-butylphenylsilanediol, isobutylphenylsilanediol, tert-butylphenylsilanediol, diphenylsilanediol, ethylmethylphenylsilanol, n-propylmethylphenylsilanol, isopropylmethylphenylsilanol, n-butylmethylphenylsilanol, isobutylmethylphenylsilanol, tert-butylmethylphenylsilanol Ethyl n-propylphenylsilanol, ethylisopropylphenylsilanol, n-butylethylphenylsilanol, isobutylethylphenylsilanol, tert-butylethylphenylsilanol, methyldiphenylsilanol, ethyldiphenylsilanol, n-propyldiphenylsilanol, isopropyldiphenylsilanol, n-butyldiphenylsilanol, isobutyldiphenylsilanol, tert-butyldiphenylsilanol, phenylsilanetriol, 1,4-bis (trihydroxysilyl) benzene, 1,4-bis (methyldihydroxysilyl) benzene, 1,4-bis ( Ethyldihydroxysilyl) benzene, 1,4-bis (propyldihydroxysilyl) benzene, 1,4-bis (butyldihi Loxysilyl) benzene, 1,4-bis (dimethylhydroxysilyl) benzene, 1,4-bis (diethylhydroxysilyl) benzene, 1,4-bis (dipropylhydroxysilyl) benzene, 1,4-bis (dibutylhydroxysilyl) ) Benzene and the like.

  Examples of the aluminum chelate compound include tris (acetylacetonate) aluminum, acetylacetate aluminum diisopropylate, and the like.

  When these (1) adhesion imparting agents are used, it is preferable to contain 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of component (a). preferable.

[Other components: (2) Surfactant or leveling agent]
Further, the polyimide resin composition of the present invention may contain an appropriate (2) surfactant or leveling agent in order to prevent coating properties, for example, striation (film thickness unevenness). Examples of such surfactants or leveling agents include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, and the like.

  Commercially available products include Megafax F171, F173, R-08 (trade name, manufactured by Dainippon Ink & Chemicals, Inc. (DIC Corporation)), Florard FC430, FC431 (trade name, manufactured by Sumitomo 3M Limited), organosiloxane Examples thereof include polymers KP341, KBM303, KBM403, and KBM803 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).

[Resin composition]
Although the manufacturing method of a resin composition is not specifically limited, For example, when (a) the reaction solvent at the time of synthesize | combining a polyimide precursor (polyamic acid) and (b) the organic solvent are the same, a) In the temperature range of room temperature (25 ° C.) to 80 ° C., the component (b) and other additives as required are added to the polyamic acid solution, followed by stirring and mixing. For this stirring and mixing, an apparatus such as a three-one motor (manufactured by Shinto Chemical Co., Ltd.) equipped with a stirring blade, a rotation and revolution mixer, or the like can be used. Moreover, you may add the heat | fever of 40-100 degreeC as needed. (A) When the reaction solvent used when synthesizing the polyamic acid is different from the organic solvent (b), the reaction solvent in the synthesized polyamic acid solution is removed by reprecipitation or solvent distillation, and (a) Examples thereof include a method obtained by adding (b) an organic solvent and, if necessary, other additives and stirring and mixing in the temperature range of room temperature to 80 ° C. after obtaining the polyamic acid.

  The viscosity at 25 ° C. of the resin composition of the present invention is preferably 0.5 to 100 Pa · s, preferably 1 to 30 Pa · s from the viewpoint of workability in the coating process, although it depends on the intended use and purpose. More preferably, it is 5-20 Pa.s. More preferably, it is s.

[Polyimide molded product]
The polyimide molded body of the present invention can be obtained by forming a resin film obtained by applying and drying the resin composition of the present invention and subjecting it to heat treatment (imidization). The polyimide molded body is selected from forms such as a film shape, a film shape, and a sheet shape depending on the intended use and purpose.

  The method for producing a polyimide molded body includes (1) a step of applying the resin composition of the present invention on a substrate, and (2) a step of drying the applied resin film with heat at 80 to 200 ° C. to form a resin film. (3) The step of heat-treating the resin film after drying comprises a step of imidizing the polyimide precursor in the resin composition by heating at 300 ° C. or higher.

(1) Application | coating process The application | coating method used at an application | coating process does not have a restriction | limiting in particular, According to desired application | coating thickness, the viscosity of a resin composition, etc., it can select and use a well-known application | coating method suitably. Specifically, doctor blades, knife coaters, air knife coaters, roll coaters, rotary coaters, flow coaters, die coaters, bar coaters and other coating methods, spin coating, spray coating, dip coating and other coating methods, screen printing and gravure Printing techniques represented by printing and the like can also be applied. The substrate on which the resin composition is applied is not particularly limited as long as it has heat resistance at the drying temperature in the subsequent steps and has good peelability. Examples thereof include a substrate made of glass, a silicon wafer or the like, and a support made of PET (polyethylene terephthalate), OPP (stretched polypropylene) or the like. Other base materials include glass substrates, metal substrates such as stainless steel, alumina, copper, nickel, polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, poly A resin substrate such as ether sulfone, polyphenylene sulfone, or polyphenylene sulfide is used. The organic solvent remaining in the resin film is removed, and the imidization reaction proceeds.

  The coating thickness of the resin composition of the present invention is appropriately adjusted depending on the thickness of the objective molded article and the ratio of the resin non-volatile content in the resin composition, but is usually about 1 to 1000 μm. The resin non-volatile content can be obtained by the method described above. The coating step is usually performed at room temperature, but the resin composition may be heated in the range of 40 to 80 ° C. for the purpose of reducing the viscosity and improving workability.

  Following the coating process, (2) a drying process is performed. The drying step is performed for the purpose of removing the organic solvent. A drying process can utilize apparatuses, such as a hotplate, a box-type dryer, and a conveyor type dryer, It is preferable to carry out at 80-200 degreeC, and it is more preferable to carry out at 100-150 degreeC.

  Subsequently, (3) a heating step is performed. This heating step is a step of (2) removing the organic solvent remaining in the resin film in the drying step and advancing the imidization reaction of the polyamic acid in the resin composition. A heating process is performed using apparatuses, such as an inert gas oven, a hot plate, a box type dryer, and a conveyor type dryer. Further, this step may be performed simultaneously with the (2) drying step or sequentially. Although it may be in an air atmosphere, it is recommended to carry out in an inert gas atmosphere from the viewpoint of safety and oxidation prevention. Examples of the inert gas include nitrogen and argon. Although heating temperature is based also on the kind of (b) organic solvent, 250 to 400 degreeC is preferable and it is more preferable that it is 300 to 350 degreeC. If it is lower than 250 ° C., imidization becomes insufficient, and if it is higher than 400 ° C., the film is likely to be colored, and there may be a problem that heat resistance is not provided. The heating time is usually about 0.5 to 3 hours.

  Further, depending on the intended use and purpose of the polyimide molded body, (4) a peeling step of peeling the resin composition from the base material is required after the heating step. This peeling process is implemented after cooling the molded object on a base material to room temperature-about 50 degreeC. In order to easily perform the peeling operation, a release agent may be applied to the substrate as necessary before applying the resin composition of the present invention. Examples of such release agents include vegetable oil-based, silicon-based, fluorine-based and alkyd-based release agents.

  The obtained polyimide molded body can also form a pattern by a resist process according to a use. In the resist process, for example, after (3) the heating step or (4) the peeling step, a resist is applied, and a pattern is formed by exposure and development. The resist material and the material used for etching are not particularly limited as long as they are used in a normal resist process. For example, generally well-known etching solutions include hydrazine hydrate, potassium hydroxide aqueous solution, sodium hydroxide aqueous solution and the like. In addition to these wet etchings, dry methods such as oxygen plasma etching and oxygen sputter etching can also be employed. After pattern formation, the resist is peeled off from the polyimide molded body using an organic solvent. Examples of the organic solvent include ethanolamine, NMP, DMSO and the like, and a mixture thereof can also be used.

  The method for producing a polyimide molded body according to the present invention is useful for producing a polyimide molded body having a thickness of 1 to 500 μm. It is preferable to produce a polyimide molded body having a thickness of 1 to 100 μm because the effects of the present invention are further improved.

  The amount of the remaining organic solvent after the production of the polyimide molded body of the present invention is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less.

  As for the mechanical properties of the polyimide molded body of the present invention, the tensile elastic modulus is preferably 1.5 GPa or more in both the width direction and the operation direction, and more preferably 1.7 to 6.5 GPa. The tensile strength is preferably 45 MPa or more, and more preferably 50 to 200 MPa. The elongation at break is preferably 50 to 150%, more preferably 80 to 150%. All of these mechanical properties can be determined by a tensile test using a tensile test apparatus. If the polyimide molded body has these mechanical properties, it is considered to have sufficient toughness as a polyimide molded body used in the fields of optical communication and display devices, and can be used practically.

  The glass transition temperature (Tg) of the polyimide molded body of the present invention is usually 250 to 400 ° C, preferably 300 to 400 ° C. This value is regarded as having sufficient heat resistance as a polyimide molded body used in the fields of optical communication and display devices. The glass transition temperature is a value obtained by the method described in Examples described later.

  The transparency of the polyimide molded body of the present invention is such that the transmittance at 400 nm or more is preferably 80% or more, more preferably 90% or more at a film thickness of 10 μm. This value is regarded as having sufficient transparency as a polyimide molded body used in the fields of optical communication and display devices.

[Plastic substrate / Protective film / Electric / electronic parts]
The plastic substrate and protective film of the present invention are characterized by comprising the above polyimide molded body. As the manufacturing method, a conventionally known manufacturing method can be used. For example, the resin composition of the present invention is applied to a temporary fixing substrate, dried and heated, and then subjected to the resist process, which is used as a plastic substrate used as a transparent conductive film (ITO) substrate and a thin film transistor (TFT) substrate. can do. The resin composition of the present invention can be applied to a temporarily fixed substrate, dried and heated, peeled from the temporarily fixed substrate, and used as a film.

  Since the polyimide molded body of the present invention has heat resistance, transparency and toughness, the plastic substrate and the protective film can be used for electronic parts such as liquid crystal displays, organic electroluminescence displays, and field emission displays. Specifically, it can be used for an electronic component as a cover film, a thin film transistor (TFT) substrate, or the like. Further, it can be used as a flexible display substrate such as electronic paper, a protective film for a color filter, and the like. Furthermore, it can be used in the field of display devices as an alternative to glass substrates such as transparent conductive film substrates and TFT substrates. It can also be used in the field of optical communications such as optical fibers and optical waveguides. Furthermore, it can also be used as a surface protective film for solar cells.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples.

[Synthesis of Polymer I]
A 0.2-liter flask equipped with a stirrer and a thermometer was charged with 63.2 g (637 mmol) of N-methylpyrrolidone and 11.1 g (30.0 mmol) of 4,4′-bis (4-aminophenoxy) biphenyl. After stirring and dissolving, cyclohexanetetracarboxylic acid was heated in a dryer (160 ° C., 24 hours) and dehydrated and ring-closed (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic dianhydride 6.72 g (30. 0 mmol) was added and stirred well to dissolve completely. Then, it stirred for about 70 hours until molecular weight became fixed, and obtained the polyamic acid (polyimide precursor) (henceforth polymer I). The weight average molecular weight of polymer I determined by GPC standard polystyrene conversion was 89,000, and the degree of dispersion was 2.4.

[Synthesis of Polymers II to XII]
In the same manner as for polymer I, blending was performed as shown in Table 1 to synthesize polymers II to XII. The units of numerical values of amines 1 to 9, acids 1 to 3 and NMP in Table 1 are mmoles. The amines 1 to 9 and acids 1 and 2 used are as follows.
Amine 1: 4,4′-bis (4-aminophenoxy) biphenylamine 2: p-phenylenediamine amine 3: 4,4′-oxydianiline amine 4: 2,2′-bis (trifluoromethyl) benzidine amine 5: 1,4-bis (4-aminophenoxy) benzenamine 6: 2,2′-bis (4- (4-aminophenoxy) phenyl) propanamine 7: bis (4- (4-aminophenoxy) phenyl) Sulfonamine 8: 4,4'-methylenebis (cyclohexylamine)
Amine 9: 3,3′-bis (trifluoromethyl) benzidine acid 1: (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic acid 2: (1S, 2S, 4R, 5R) -cyclohexanetetracarboxylic acid 3: 3,3 ′, 4,4′-tetracarboxydiphenyl ether

(Measurement conditions for weight average molecular weight)
The weight average molecular weight of the synthesized polymer was determined in terms of standard polystyrene using a gel permeation chromatography method (GPC, apparatus is manufactured by Hitachi, Ltd., column is gel pack manufactured by Hitachi Chemical Co., Ltd.).
Specifically, the weight average molecular weight of each polymer was measured by GPC with the following apparatus and conditions.
Measuring device: Detector L4000UV manufactured by Hitachi, Ltd.
Pump: Hitachi Ltd. L6000
C-R4A Chromatopac manufactured by Shimadzu Corporation
Measurement conditions: Column Gelpack GL-S300MDT-5 × 2 eluent: THF / DMF = 1/1 (volume ratio)
LiBr (0.03 mol / l), H ₃ PO ₄ (0.06 mol / l)
Flow rate: 1.0 ml / min, detector: UV 270 nm
The measurement was performed using a solution of 1 ml of a solvent [THF / DMF = 1/1 (volume ratio)] with respect to 0.5 mg of the polymer.

[Example 1]
(Production of cured film)
When the polymer I was diluted with NMP to a viscosity at which it could be easily applied and the residual solid content (NV) was measured, it was 14% by mass. Here, the residual solid content is a ratio of the resin non-volatile content in the resin composition, and the mass (the mass of the metal petri dish and the polyamic acid) is obtained by taking the polyamic acid solution (about 1 g as a guide) into a metal petri dish having a known mass. , Hereinafter referred to as mass before heating), and then heated on a hot plate at 200 ° C. for 2 hours to sufficiently evaporate the solvent (mass of metal petri dish and solute, hereinafter referred to as mass after heating) ) Is measured, and (mass after heating−mass of metal petri dish) ÷ (mass before heating−mass of metal petri dish) × 100 is calculated.
This was filtered using a 5 μm filter (Millipore, SLLS025NS). The obtained resin composition was spin-coated on a silicon wafer and dried at 120 ° C. for 3 minutes to form a coating film having a dry film thickness of 14 to 18 μm. This was further fully cured in a nitrogen atmosphere using an inert gas oven to obtain a cured film having a cured film thickness of 9 to 11 μm. The conditions for full cure with an inert gas oven are as follows.

(Full cure condition with inert gas oven)
Apparatus: Inert gas oven manufactured by Koyo Thermo System Co., Ltd. Conditions: Temperature rise Room temperature to 200 ° C (5 ° C / min)
Hold 200 ° C (20 minutes)
200 ° C to 300 ° C (5 ° C / min)
Hold 300 ° C (60 minutes)
Cooling 300 ° C to room temperature (60 minutes)

(Evaluation of film properties)
Next, this cured film was peeled from the silicon wafer using a 4.9% by mass hydrofluoric acid aqueous solution, washed with water, dried, and then examined for glass transition point (Tg), elongation at break, and transmittance. Tg was determined from the inflection point of thermal expansion using a TMA / SS6000 manufactured by Seiko Instruments Inc. at a temperature rising rate of 5 ° C./min. The elongation at break and elastic modulus were determined from a tensile test using an autograph AGS-100NH manufactured by Shimadzu Corporation. Moreover, the transmittance | permeability was measured using U-3310 (Hitachi Ltd. spectrophotometer), and calculated | required the value converted into 10 micrometers using Lambert-Beer's law.

(Evaluation of chemical resistance)
The cured film formed on the silicon wafer by the above-described method was immersed in a dimethyl sulfoxide: monoethanolamine = 30: 70 mass ratio solution at 80 ° C. for 10 minutes, and the chemical resistance of the cured film was evaluated. A cured film having no crack was evaluated as “◯”, and a crack having a crack was evaluated as “×”. In addition, the change of film thickness before and after the chemical resistance evaluation test is less than ± 0.3% “A”, the change of ± 0.3% to ± 0.5% is “B”, ± 0.5 The larger one was rated as “C”.

[Examples 2 to 4, Comparative Examples 1 to 8]
A cured film was prepared in the same manner as in Example 1, glass transition point (Tg), elongation at break, transmittance measurement and chemical resistance were evaluated. The results are shown in Table 1.

As in Examples 1 to 4, when a resin composition containing a polyimide precursor obtained from a diamine having a cyclohexanetetracarboxylic acid and an ether bond and a biphenyl skeleton is used, it exhibits good transmittance and is resistant to chemicals. An excellent cured film could be obtained. Moreover, it turned out that these cured films have sufficient heat resistance and mechanical characteristics. In cyclohexanetetracarboxylic acid, Tg slightly decreases, but acid 1 (1R, 2S, 4S, 5R) -cyclohexanetetracarboxylic acid uses acid 2 (1S, 2S, 4R, 5R) -cyclohexanetetra. The transmittance is higher than that using carboxylic acid, and the mechanical properties are slightly superior.
On the other hand, p-phenylenediamine of amine 2 (Comparative Example 1), 4,4′-oxydianiline (Comparative Example 2) of amine 3, When 2'-bis (trifluoromethyl) benzidine (Comparative Example 3) is used, the transmittance is relatively good, but it is inferior to chemical-resistant cracks and film thickness changes. Furthermore, 1,4-bis (4-aminophenoxy) benzene of amine 5 (Comparative Example 4) and 2,2′-bis (4- (4 of amine 6), which do not have an ether bond and a biphenyl skeleton in diamine. -Aminophenoxy) phenyl) propane (Comparative Example 5), amine 7 bis (4- (4-aminophenoxy) phenyl) sulfone (Comparative Example 6), amine 8 4,4'-methylenebis (cyclohexylamine) (comparative) Example 7) Amine 9,3'-bis (trifluoromethyl) benzidine (Comparative Example 8) has a transmittance of 87.1 to 89.1%, which is significantly inferior to the examples and is resistant to chemicals. Also inferior to changes in film thickness.
A polyimide resin using a polyimide precursor (polyamide acid) obtained by using cyclohexanetetracarboxylic acid as the acid component of the present invention and a diamine having an ether bond and a biphenyl skeleton as the diamine component is excellent in transparency and chemical resistance.

  As described above, a film obtained by heat-curing the resin composition according to the present invention is excellent in transparency and chemical resistance, and further excellent in heat resistance and mechanical properties, and thus is suitably used as a display substrate or a protective film. be able to. In addition, it is possible to provide electrical / electronic components (electrical insulating films and liquid crystal displays in various electronic devices, organic electroluminescence displays, electronic paper, solar cells, and the like) provided with the base material or protective film.

Claims (10)

(A) A polyimide precursor having a repeating unit represented by formula (I).

(In the general formula (I), X represents a diamine residue having an ether bond and a biphenyl skeleton) The polyimide precursor of Claim 1 in which the polyimide precursor which has a repeating unit shown by general formula (I) has a repeating unit shown by general formula (II).

(In general formula (II), n represents an integer of 1 to 3)   A resin composition containing the polyimide precursor according to claim 1.   The resin composition according to claim 3 containing an organic solvent.   The polyimide molded body obtained by heating the resin composition of Claim 4.   A plastic substrate comprising the polyimide molded body according to claim 5.   A protective film comprising the polyimide molded body according to claim 5.   An electronic component having the plastic substrate according to claim 6 or the protective film according to claim 7.   A display device comprising the plastic substrate according to claim 6 or the protective film according to claim 7.   The manufacturing method of the polyimide molded body which includes the process of apply | coating and drying the resin composition of Claim 3 or 4 on a base material, and forming a resin film, and the process of heat-processing the resin film after the said drying.