KR102044260B1 - Highly transparent polyimide - Google Patents

Abstract

The polyimide precursor which is a copolymer which has a structural unit represented by following formula (I) and (II).

Description

Highly transparent polyimide {HIGHLY TRANSPARENT POLYIMIDE}

The present invention relates to a polyimide precursor, a resin composition containing the same, a polyimide comprising the same, a method for producing a polyimide molded body, a polyimide molded body obtained from the production method, a transparent substrate, a protective film, an electronic component having the same, and a display device. , And a solar cell module.

In addition to high heat resistance, polyimide resin has the electrical characteristics and mechanical characteristics which are excellent in insulation. Since it has such a characteristic, polyimide resin is used as a surface protection film and an interlayer insulation film of a semiconductor device.

On the other hand, in the field of a display apparatus, in recent years, replacing the transparent substrates, such as a glass substrate and a cover glass, with a transparent substrate using resin from the request of improvement of damage resistance, weight reduction, thickness reduction, etc. is examined. The display device refers to a liquid crystal display, an organic electroluminescence display, an electronic paper, and the like. In particular, in display devices for mobile information communication devices such as portable information terminals such as mobile phones, electronic notebooks, and laptop PCs, there is a strong demand for transparent substrates using resins instead of conventional glass substrates.

In addition to heat resistance and mechanical properties, the transparent substrate used for the display device is required to have high transparency and low birefringence from the viewpoint of high visibility. In addition, the transparent substrate used in the display device has a coefficient of thermal expansion (hereinafter referred to as CTE (Coefficient Of Thermal Expansion)) in order to prevent deterioration of alignment accuracy due to heating during TFT (Thin Film Transistor) formation. Small things are required.

In general, polyimide resins are colored yellowish brown by the formation of intramolecular conjugates and charge transfer complexes. Therefore, a method of inhibiting the formation of the charge transfer complex and expressing transparency by introducing fluorine into the polyimide resin, imparting flexibility to the main chain, and introducing a bulky side chain has been proposed ( Non-Patent Document 1). Moreover, the method of expressing transparency by using the ring-cyclic or all-cyclic polyimide resin which does not form a charge transfer complex is also proposed (patent document 1, 2).

However, when the transparent substrate was formed using such a polyimide resin, since the CTE was large (for example, 50 × 10 ⁻⁶ K ⁻¹ ), there was a problem that the positioning accuracy deteriorated. Therefore, the polyimide which is excellent in transparency and formed of 3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride and trans-1, 4- diamino cyclohexane as a polyimide resin with small CTE (patent document 3 ) Is proposed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-348374 Patent Document 2: Japanese Patent Publication No. 2005-015629 Patent Document 3: Japanese Patent Application Laid-Open No. 2002-161136

Non Patent Literature 1: Polymer (US), Vol. 47, p. 2337-2348, 2006

Summary of the Invention

However, when the polyimide resin of Patent Document 3 is used, the CTE becomes small (for example, 20 × 10 ⁻⁶ K ⁻¹ ), but the elastic modulus (tensile modulus) is large and the birefringence is also large, so that the display device is transparent. It was difficult to use as a board | substrate or a protective film.

An object of the present invention is to provide a polyimide precursor having sufficient transparency, giving a polyimide molded article having a small CTE, a low elastic modulus, and a small birefringence.

The polyimide precursor of this invention is a copolymer which has a structural unit represented by following formula (I) and (II).

[Tue 1]

This invention provides the resin composition which has the said polyimide precursor. Moreover, it is preferable that the resin composition of this invention contains the (b) organic solvent. Moreover, it is preferable to use the polyimide precursor or resin composition of this invention for forming the transparent substrate of a display apparatus.

The present invention provides a polyimide obtained by heating the polyimide precursor.

This invention provides the manufacturing method of the polyimide molded body characterized by including 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. Moreover, the polyimide molded body obtained by the said manufacturing method is provided.

Moreover, this invention provides the transparent substrate and protective film which consist of the said polyimide molded object. Moreover, this invention provides the electronic component, display apparatus, and solar cell module which have this transparent substrate and its protective film.

ADVANTAGE OF THE INVENTION According to this invention, the polyimide precursor which has sufficient transparency, provides a polyimide molded body with small CTE, small elastic modulus, and small birefringence can be provided.

To practice the invention  Form for

EMBODIMENT OF THE INVENTION Below, embodiment of the polyimide precursor, resin composition, and polyimide molded object of this invention, its manufacturing method, and an electronic component is explained in full detail. In addition, this invention is not limited by this embodiment.

[(a) polyimide precursor]

The polyimide precursor of this invention is a copolymer which has a structural unit represented by following formula (I) and (II).

[Tue 2]

As for the ratio of structural unit (I) and (II), (I) :( II) = 5: 95-95: 5 is preferable from a viewpoint of CTE, elastic modulus, and birefringence of the hardened | cured material obtained. Further, from the viewpoint of birefringence, (I) :( II) = 30:70 to 95: 5 is more preferable, and from the viewpoint of CTE, (I) :( II) = 50:50 to 70:30 is more preferable.

In addition, from the viewpoint of further suppressing salt formation during synthesis and making it easier to control the reaction, (I) :( II) = 30:70 to 95: 5 is preferable, and (I) :( II) = 50: 50-95: 5 are more preferable.

The ratios of the formulas (I) and (II) can be obtained by, for example, measuring a ¹ HNMR spectrum. In addition, a copolymer may be a block copolymer or a random copolymer.

The polyimide precursor (polyamic acid) of this invention is 3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride, 4,4'- oxydiphthalic dianhydride, and 1, 4- diamino cyclo It can be obtained by polymerizing hexane.

By using 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (an acid dianhydride obtained by heating 3,3', 4,4'-biphenyltetracarboxylic acid and dehydrating ring closure) It is thought that the hardened | cured material obtained expresses favorable heat resistance, and can also make CTE small.

The hardened | cured material obtained by using a 4,4'- oxydiphthalic dianhydride (an acid dianhydride obtained by heating 3,3 ', 4,4'- tetracarboxydiphenyl ether and dehydrating and ring-closing) uses favorable heat resistance and transparency. It is thought that the expression and the birefringence can be reduced.

As the raw material tetracarboxylic acid (3,3 ', 4,4'-biphenyltetracarboxylic acid, 4,4'-oxydiphthalic acid), these acid anhydrides are usually used, but these acids or other derivatives thereof are used. You can also use

Moreover, it is thought that the hardened | cured material obtained can express favorable transparency and chemical-resistance by using 1, 4- diamino cyclohexane.

From the viewpoint of expressing good transparency and heat resistance and decreasing CTE, 1,4-diaminocyclohexane is preferably trans 1,4-diaminocyclohexane. When trans 1, 4- diamino cyclohexane is used, it is preferable that the three-dimensional structure of the two amino groups couple | bonded with the cyclohexane ring is an equilateral arrangement.

The ratio of the structural units (I) and (II) is tetracarboxylic acids (3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride) and diamine It can adjust by changing the ratio of (1, 4- diamino cyclohexane).

As for the molecular weight of the polyamic acid (polyimide precursor) of this invention, 10000-500000 are preferable at a weight average molecular weight, 10000-300000 are more preferable, 20000-200000 are especially preferable.

If the weight average molecular weight is less than 10000, it is difficult to form a resin film in the step of heating the applied resin composition, and there is a fear that the mechanical properties may be insufficient even if it is formed. When the weight average molecular weight is larger than 500000, it is difficult to control the weight average molecular weight at the time of synthesis of polyamic acid, and there exists a possibility that it may become difficult to obtain the resin composition of moderate viscosity.

The weight-average molecular weight was determined by standard polystyrene conversion using gel permeation chromatography (GPC) (for example, the apparatus manufactured by Hitachi Kasei Kogyo Co., Ltd. L4000 UV, and the column manufactured by Hitachi Kasei Kogyo Co., Ltd.). You can get it.

The polyimide precursor (polyamic acid) of this invention can be synthesize | combined by a conventionally well-known synthetic method. For example, after dissolving a predetermined amount of 1,4-diaminocyclohexane in a solvent, 3,3 ', 4,4'-biphenyltetracarboxylic acid and 4,4'-jade are obtained in the obtained diamine solution. Predetermined amount of tetracarboxylic dianhydride obtained by heating each sidiphthalic acid at 160 degreeC with a dryer for 24 hours, and dehydrating ring-closure is added and stirred.

When dissolving each monomer component, you may heat as needed.

As for reaction temperature, -30-200 degreeC is preferable, 20-180 degreeC is more preferable, 30-100 degreeC is especially preferable. Stirring is continued at room temperature (20-25 degreeC) or a suitable reaction temperature as it is, and let the end point of reaction be the time when the viscosity of polyamic acid became constant. A viscosity can be measured at 25 degreeC using an E-type clay meter (made by Toki Sangyo Co., Ltd.).

The reaction can be completed in usually 3 to 100 hours.

The solvent for the reaction is not particularly limited as long as it is a solvent capable of dissolving diamine, tetracarboxylic acids and produced polyamic acid.

As a specific example of such a solvent, a non-flotone solvent, a phenol solvent, an ether, a glycol solvent, etc. are mentioned. Specifically, as an aflotonic solvent, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl caprolactam, 1,3-dimethylimida cooking Amide solvents such as dinon and tetramethyl urea; lactone solvents such as γ-butyrolactone and γ-valerolactone; Phosphorus-containing amide solvents such as hexamethylphosphoricamide and hexamethylphosphinetriamide; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; 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); and the like. As a phenolic solvent, a 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. Examples of the ether and glycol solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane and bis [2- (2-methoxy Oxy) ethyl] ether, tetrahydrofuran, 1, 4- dioxane, etc. are mentioned. Especially, N-methyl-2-pyrrolidone is preferable from a viewpoint of solubility and coating film formation property. You may use these reaction solvent individually or in mixture of 2 or more types.

The polyimide precursor (polyamic acid) of this invention can be obtained as a solution (henceforth a polyamic acid solution) which uses the said reaction solvent as a solvent normally.

As for the ratio of the polyamic-acid component (resin non-volatile content: hereafter called a solute) with respect to the whole quantity of the obtained polyamic-acid solution, 5-60 mass% is preferable from a viewpoint of coating film formability, 10-50 mass% is more preferable. 10-40 mass% is especially preferable.

The ratio of the solute is obtained by taking a polyamic acid solution (based on about 1 g) into a metal chalet having a known mass beforehand, and measuring the mass (mass of the metal chalet and polyamic acid, hereinafter referred to as mass before heating), After heating for 2 hours on a hot plate, the mass after the solvent was sufficiently volatilized (mass of the metal chalet and solute, hereinafter referred to as the mass after heating) was measured, and (mass after heating-mass of metal chalet) ÷ (preheating). Mass-the mass of a metal chalet) x 100.

500-20000 mPa * s is preferable at 25 degreeC, as for the solution viscosity of the said polyamic acid solution, 2000-100000 mPa * s is more preferable, 5000-30000 mPa * s is especially preferable. Solution viscosity can be measured using E-type clay meter (VISCONICEHD by Toki Sangyo Co., Ltd.).

If the solution viscosity is lower than 500 mPa · s, application at the time of film formation is difficult, and if higher than 200000 mPa · s, there is a concern that agitation at the time of synthesis becomes difficult. However, even if the solution has a high viscosity at the time of polyamic acid synthesis, it is also possible to obtain a polyamic acid solution having a good handleability by adding and stirring a solvent after completion of the reaction.

The polyimide of this invention can be obtained by heating and dehydrating the said polyimide precursor.

[Resin composition]

The resin composition of this invention contains said (a) polyimide precursor, Preferably it contains the organic solvent.

[(b) Organic Solvent]

(b) There is no restriction | limiting in particular if the organic solvent can melt | dissolve the polyimide precursor (polyamic acid) of this invention, As this (b) organic solvent, the synthesis | combination of said (a) polyimide precursor (polyamic acid) is carried out. The solvent which can be used at the time can be used. The organic solvent (b) may be the same as or different from the solvent used in the synthesis of the (a) polyamic acid.

(b) It is preferable to adjust and add a component so that the viscosity in 25 degreeC of a resin composition may be 0.5 Pa * s-100 Pa * s.

Moreover, 60-210 degreeC is preferable, as for the boiling point in the normal pressure of (b) organic solvent, 100-205 degreeC is more preferable, 140-180 degreeC is especially preferable.

If the boiling point is higher than 210 ° C., the drying step is necessary for a long time. If the boiling point is lower than 60 ° C., there is a possibility that behavior occurs on the surface of the resin film in the drying step, bubbles are mixed in the resin film, and a uniform film cannot be obtained. have.

[Other Ingredients]

The resin composition of this invention may contain (1) adhesiveness giving agent, (2) surfactant, a leveling agent, etc. other than said (a) and (b) component.

In addition, the composition of this invention may consist essentially of additives, such as an adhesive imparting agent, surfactant, a leveling agent, and may consist only of these components, and said (a) and (b) component. . "Substantially consists" means that the said composition mainly consists of said (a) and (b) component (for example, 90 weight% or more of the whole composition), and can contain the said additive other than these components. It is.

[Other components: (1) Adhesion imparting agent]

In order to improve the adhesiveness with the board | substrate of a cured film, the resin composition of this invention may contain (1) adhesiveness giving agents, such as an organosilane compound and an aluminum chelate compound.

As an organosilane compound, vinyltriethoxysilane, (gamma)-glycidoxy propyl triethoxysilane, (gamma)-methacryloxypropyl trimethoxysilane, urea propyl triethoxysilane, and methylphenylsilanediol, for example. , Ethylphenylsilanediol, n-propylphenylsilanediol, isopropylphenylsilanediol, n-butylphenylsilanediol, isobutylphenylsilanediol, tert-butylphenylsilanediol, diphenylsilanediol, ethylmethylphenylsilanol, n -Propylmethylphenylsilanol, isopropylmethylphenylsilanol, n-butylmethylphenylsilanol, isobutylmethylphenylsilanol, tert-butylmethylphenylsilanol, ethyl n-propylphenylsilanol, ethyl isopropylphenylsilanol, n-butyl Ethylphenylsilanol, isobutylethylphenylsilanol, tert-butylethylphenylsilanol, methyldiphenylsilanol, ethyldiphenylsilanol, n-propyldiphenylsilanol, isopropyldiphenylsilanol, n-butyl Diphenylsilanol, isobutyldiphenyl Silanol, tert-butyldiphenylsilanol, phenylsilanetriol, 1,4-bis (trihydroxysilyl) benzene, 1,4-bis (methyldihydroxysilyl) benzene, 1,4-bis (ethyl Dihydroxysilyl) benzene, 1,4-bis (propyldihydroxysilyl) benzene, 1,4-bis (butyldihydroxysilyl) benzene, 1,4-bis (dimethylhydroxysilyl) benzene, 1, 4-bis (diethyl hydroxy silyl) benzene, 1, 4-bis (dipropyl hydroxy silyl) benzene, 1, 4-bis (dibutyl hydroxy silyl) benzene, etc. are mentioned.

As an aluminum chelate compound, tris (acetylacetonate) aluminum, acetyl acetate aluminum diisopropylate, etc. are mentioned, for example.

When using these (1) adhesiveness imparting agents, it is preferable to contain 0.1-20 mass parts with respect to 100 mass parts of (a) component, and it is more preferable to contain 0.5-10 mass parts.

[Other components: (2) surfactant or leveling agent]

Moreover, the resin composition of this invention may contain surfactant (2) or a leveling agent from a viewpoint of preventing applicability | paintability, for example, striation (film thickness unevenness).

As a surfactant or a leveling agent, polyoxyethylene uraryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenol ether, etc. are mentioned, for example.

As a commercial item, Megafax F171, F173, R-08 (made by Dainippon ink Kasei Kogyo Co., Ltd., brand name), Florade FC430, FC431 (made by Sumitomo 3M Co., Ltd., brand name), organo Siloxane polymers KP341, KBM303, KBM403, KBM803 (Shin-Etsu Chemical Co., Ltd. make, brand name), etc. are mentioned.

Although the viscosity at 25 degrees C of the resin composition of this invention depends also on a use use and an objective, 0.5-100 Pa.s is preferable from a viewpoint of workability in an application | coating process, 1-30 Pa.s is more preferable, 5-20 Pa.s is especially preferable. Here, a viscosity can be measured using an E-type clay meter (VISCONICEHD by Toki Sangyo Co., Ltd.).

Although the manufacturing method of the resin composition of this invention is not specifically limited, For example, when the solvent used when synthesize | combining (a) polyamic acid and (b) the organic solvent is the same, the synthesized polyamic-acid solution Can be made into a resin composition. Moreover, (b) component and another additive may be added and stirred and mixed in the temperature range of room temperature (25 degreeC)-80 degreeC as needed.

This stirring mixing can use apparatuses, such as a three-one motor (made by Shinto Chemical Co., Ltd.) provided with a stirring blade, and a rotating revolution mixer. Moreover, you may add 40-100 degreeC heat as needed.

Moreover, when (a) the solvent used when synthesize | combining polyamic acid and (b) organic solvent differ, the solvent in the synthesized polyamic acid solution is removed by reprecipitation or a solvent distillation method, After obtaining (a) polyamic acid, you may add and add the (b) organic solvent and other additives as needed in the temperature range of room temperature-80 degreeC, and stirring and mixing.

The resin composition of this invention can be used in order to form the transparent substrate of display apparatuses, such as a liquid crystal display, an organic electroluminescent display, a field emission display, and an electronic paper.

Specifically, it can be used to form a substrate of a thin film transistor (TFT), a substrate of a color filter, a substrate of a transparent conductive film (ITO, Indium Thin Oxide), and the like.

[Polyimide molded body]

The polyimide molded body of this invention can be obtained by forming the resin film obtained by apply | coating and drying the resin composition of this invention to a base material, and heat-processing (imidizing) this. Moreover, the polyimide molded object can be used as a form of a film form, a film form, a sheet form, etc. according to a use use and the purpose.

The method for producing the polyimide molded article is preferably (1) a step of applying the resin composition of the present invention on a substrate to form a resin film, and (2) drying the applied resin film with a heat of 80 to 200 ° C. to form a resin film. It is a process of forming and (3) heat-processing the resin film after drying, Comprising: The process of imidating the polyimide precursor in a resin composition by heating at 300 degreeC or more.

(1) application process

There is no restriction | limiting in particular in the coating method used at a coating process, According to a desired coating thickness, the viscosity of a resin composition, etc., a well-known coating method can be selected suitably and can be used. Specifically, a coating method such as a doctor blade knife coater, an air knife coater, a roll coater, a rotary coater, a flow coater, a die coater, a bar coater, a coating method such as a spin coat, a spray coat, a dip coat, a screen printing or a gravure printing It is also possible to apply a printing technique represented by such.

As a base material which apply | coats a resin composition, if it has heat resistance in the drying temperature of a subsequent process, and peelability is favorable, it will not specifically limit. For example, the support body which consists of a base material which consists of glass, a silicon wafer, etc., PET (polyethylene terephthalate), OPP (stretched polypropylene), etc. are mentioned. In addition, the film-form polyimide molded body may include a to-be-coated object made of glass, a silicon wafer, or the like. The film- and sheet-like polyimide molded body may be a support made of PET (polyethylene terephthalate), OPP (stretched polypropylene), or the like. Can be mentioned. Other substrates include glass substrates, metal substrates such as stainless steel, alumina, copper and nickel, polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyether ether ketone, and poly Resin substrates such as ether sulfone, polyphenylene sulfone, polyphenylene sulfide and the like are used.

Although the coating thickness of the resin composition of this invention is suitably adjusted according to the thickness of the target molded object and the ratio of the resin nonvolatile component in a resin composition, it is about 1-1000 micrometers normally. The resin nonvolatile component can be obtained by the above-described measuring method. Although a coating process is normally performed at room temperature, you may heat and perform a resin composition in 40-80 degreeC in order to lower | hang a viscosity and to improve workability.

Following the application | coating process, (2) drying process is performed. The drying step is carried out for the purpose of removing the organic solvent. A drying process can use apparatuses, such as a hotplate, an upper stage dryer, and a conveyor dryer, It is preferable to carry out at 80-200 degreeC, It is more preferable to carry out at 100-150 degreeC.

(3) Then, a heating step is performed. The heating step (2) is a step of removing the organic solvent remaining in the resin film in the drying step, advancing the imidation reaction of the polyamic acid in the resin composition to obtain a cured film.

A heating process is performed using apparatuses, such as an inert gas oven, a hotplate, a bed dryer, and a conveyor dryer. This process may be performed simultaneously with the said (2) drying process, or may be performed sequentially.

Although the heating process is good also in an air atmosphere, it is recommended to carry out in an inert gas atmosphere from the viewpoint of safety and oxidation prevention. Nitrogen, argon, etc. are mentioned as an inert gas. Although heating temperature is based also on the kind of (b) organic solvent, 250 degreeC-400 degreeC is preferable and 300-350 degreeC is more preferable. If it is lower than 250 degreeC, imidization will become inadequate, and if it is higher than 400 degreeC, transparency of a polyimide molded body may fall, or heat resistance may deteriorate. Heating time is about 0.5 to 3 hours normally.

Moreover, depending on the use use and purpose of a polyimide molded object, the peeling process which peels a cured film from the (4) base material after (3) heating process is needed. This peeling process is performed after cooling the molded object on a base material to room temperature-about 50 degreeC. In order to perform a peeling operation easily, you may apply a mold release agent to a base material as needed before apply | coating the resin composition of this invention.

As a mold release agent, mold release agents, such as a vegetable oil type, a silicone type, a fluorine type, and an alkyd type, are mentioned.

The obtained polyimide molded body can form a pattern by a resist process according to a use. For example, the resist process applies a resist after (3) a heating process or (4) a peeling process, and forms a pattern by exposure, image development, etc.

The material used for the resist material and the etching is not particularly limited as long as it is used in an ordinary resist process. For example, well-known etching solutions generally include hydrazine hydrate, aqueous potassium hydroxide solution, aqueous sodium hydroxide solution and the like.

In addition to these wet etching, dry methods such as oxygen plasma etching and oxygen sputter etching are also possible. After pattern formation, a resist is peeled from a polyimide molded object using an organic solvent. Ethanolamine, NMP, DMSO, etc. are mentioned as an organic solvent, A mixture thereof can also be used.

The manufacturing method of the polyimide molded object of this invention is useful when manufacturing a polyimide molded object with a film thickness of 1-500 micrometers. It is preferable to manufacture the polyimide molded object of 1-100 micrometers of film thickness especially, in order to improve the effect of this invention further.

2 mass% or less is preferable, as for the amount of the residual organic solvent in the polyimide molded body after the (3) heating process of this invention, 1 mass% or less is more preferable, 0.5 mass% or less is more preferable. The amount of the remaining organic solvent in the polyimide molded body can be measured by differential thermal weight simultaneous measurement (TG-DTA) and gas chromatography mass spectrometry (GC-MS).

The transparency of the polyimide molded body of the present invention obtained by the above production method is preferably 70% or more, more preferably 75% or more at a film thickness of 10 μm at a wavelength of 400 nm or more.

Moreover, 0.12 or less are preferable and, as for the birefringence of the polyimide molded body of this invention, 0.08 or less are more preferable. It is a value evaluated to have sufficient transparency and low birefringence as a polyimide molded body used in the field of optical communication and display.

As for the CTE (thermal expansion coefficient) of the polyimide molded body of this invention, 1-45 ppm is preferable in both the width direction and an operation direction, 5-45 ppm is more preferable, 5-30 ppm is still more preferable. When a polyimide molded body is used in a state where it is integrated with a substrate (coated material), it is preferable to adjust so that the coefficient of thermal expansion of the polyimide molded body may be about the same as that of the coated object.

250-400 degreeC is preferable and, as for the glass transition temperature (Tg) of the polyimide molded body of this invention, 300-400 degreeC is more preferable. It is a value evaluated to have sufficient heat resistance as a polyimide molded body used for the optical communication field and the display device field.

Glass transition temperature can be measured by the method as described in an Example.

In addition, CTE and glass transition temperature (Tg) can be calculated | required by carrying out TMA measurement by TMA / SS6000 by Seiko Instool.

The mechanical properties of the polyimide molded body of the present invention are preferably 1.5 GPa to 6.0 GPa, more preferably 1.7 to 6.0 GPa, and even more preferably 1.7 to 5.5 GPa in both the width direction and the operation direction of the elastic modulus (tensile modulus). If the elastic modulus is larger than 6.0 GPa, the substrate tends to bend after curing.

The tensile strength (breaking strength) is preferably 150 to 300 MPa, more preferably 150 to 200 MPa. If the tensile strength is less than 150 MPa, the film is soft, and there is a fear that handling becomes difficult when used as a substrate.

5% or more is preferable and 10% or more of break elongation is more preferable. If the elongation at break is less than 5%, the bending stress when the polyimide molded body is used as the substrate is low, and the reliability of the substrate is lowered.

All these mechanical characteristics can be calculated | required by the tension test of a tension test apparatus. If a polyimide molded body has these mechanical properties, it is considered that it has sufficient toughness as a polyimide molded body used for the optical communication field and the display apparatus field, and can be used practically.

[Transparent Substrate, Protective Film, Electronic Component]

The transparent substrate and the protective film of this invention consist of said polyimide molded object, It is characterized by the above-mentioned. The manufacturing method can use a conventionally well-known manufacturing method. For example, the resin composition of this invention can be apply | coated to a temporarily fixed base material, it can be dried and heated, and then the said resist process can be implemented according to a use, and can be used as a transparent substrate.

Moreover, the resin composition of this invention can be apply | coated to a temporarily fixed base material, it can dry and heat, it can peel from a temporarily fixed base material, and can use as a protective film.

Since the transparent substrate and the protective film of this invention have sufficient transparency, small CTE, small elastic modulus, and small birefringence, it can be used for display apparatuses, such as a liquid crystal display, an organic electroluminescent display, a field emission display, and an electronic paper. have.

Specifically, the transparent substrate of the present invention can be used as a substrate for forming a thin film transistor (TFT), a substrate for forming a color filter, a substrate for forming a transparent conductive film (ITO, Indium Thin Oxide), or the like. . When the transparent substrate of the present invention is used, breakage resistance, which has been a problem of conventional glass substrates, can be improved, and it is considered that the weight reduction and thinning of the substrate can be realized.

Furthermore, since the CTE is small in the transparent substrate of the present invention, it is possible to prevent deterioration of the positioning accuracy in the heating step during TFT formation, and also because of its high transparency and small birefringence, it is excellent in visibility.

Moreover, since the elasticity modulus is small, the transparent substrate of this invention can be used also as a board | substrate of a flexible display.

The protective film of the present invention can also be used as a flexible display substrate, a protective film for color filters, and the like. Moreover, the protective film of this invention can be used also as a surface protective film of a solar cell.

Example

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

Example 1

Into a 0.2-liter flask equipped with a stirrer and a thermometer, 56 g (564 mmol) of N-methylpyrrolidone (NMP) and 3.43 g (30 mmol) of 1,4-diaminocyclohexane were charged, stirred, and then dried in a dryer ( 160 DEG C, 24 hours) 8.39 g (28.5 mmol) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride heated and dehydrated by ring closure, and 0.47 g (1.57 oxydiphthalic dianhydride) mmol) was added and dissolved by heating and stirring in a water bath at 70 ° C. for 10 minutes for complete dissolution. Then, it stirred for about 70 hours until molecular weight became fixed, and obtained the polyamic-acid solution.

The weight average molecular weight and dispersion degree of the obtained polyamic acid were calculated | required by gel permeation chromatography (GPC) method standard polystyrene conversion. The weight average molecular weight was 31,000 and dispersion degree was 2.4.

The measurement conditions of a weight average molecular weight and dispersion degree are as follows.

Measuring device: L4000UV made by Hitachi Seisakusho Co., Ltd.

Pump: Hitachi Seisakusho Corporation L6000

C-R4AChromatopac made by Shimadzu Seisakushosha

Measurement condition: GelpackGL-S300MDT-5 * 2 made by Hitachi Kasei Kogyo Co., Ltd.

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: UV270 nm

  It was measured using a solution of 1 ml of solvent [THF / DMF = 1/1 (volume ratio)] for 0.5 mg of the polymer.

The obtained polyamic acid solution (resin composition) was diluted with NMP to a viscosity easy to apply | coat. It was 14% when the residual solid content (NV) of this resin composition was measured. Here, residual solid content is the ratio of the resin non volatile matter in a resin composition, and it calculated | required by the method of measuring the resin non volatile matter mentioned above.

This dilution liquid was filtered using a 5 micrometer filter (SLLS025NS by Millipore), the obtained resin composition was spin-coated on a silicon wafer, and it dried at 120 degreeC for 3 minutes, and formed the resin film with a film thickness of 14-18 micrometers. . This was further heated in nitrogen atmosphere using an inert gas oven, and the cured film with a film thickness of 10 micrometers was obtained.

In addition, salt formation during the synthesis reaction was evaluated. Although no salt was formed or salt formation could be confirmed, evaluation was made using B as a case where the salt is easily formed and when the salt is easily dissolved in the solvent in the resin composition, and when the salt is not easily dissolved in the solvent. The resin composition of 1 was B. FIG.

Heating conditions by an inert gas oven are as follows.

Apparatus: Inert gas oven made by Mitshiro Thermosystem

Condition: Room temperature room temperature-200 degreeC (5 degreeC / min)

Hold 200 degrees Celsius (20 minutes)

Temperature rise 200 degrees Celsius-300 degrees Celsius (5 degrees Celsius / minute)

Hold 300 degrees Celsius (60 minutes)

Cooling 300 ℃-room temperature (60 minutes)

The following evaluation was performed about the obtained cured film.

(Evaluation of birefringence)

Using the Seki Technotron Co., Ltd. METRICON 2010 type | mold, the value of the refractive index (TE) in Y-polarized wave and the refractive index (TM) in X-polarized wave in the wavelength of 1300 nm were measured, and ( Birefringence was calculated | required by Formula 1).

Birefringence = TE-TM (Equation 1)

A birefringence of 0.08 or less was defined as A (especially good), a larger than 0.08, 0.12 or less, B (good), and a larger than 0.12 C (not good).

(Evaluation of transmittance, coefficient of thermal expansion (CTE), glass transition temperature, and mechanical strength)

The obtained cured film was peeled from a silicon wafer using 4.9 mass% hydrofluoric acid aqueous solution, and it washed with water and dried, and evaluated the transmittance | permeability, CTE, glass transition temperature (Tg), and mechanical strength.

The light transmittance measured the light transmittance of wavelength 400nm or more using U-3310 (the spectrophotometer by Hitachi Seisakusho Co., Ltd.), and calculated | required the value converted into 10 micrometers using Lambert-Beer's law.

CTE was measured using the thermomechanical measuring apparatus of TMA / SS6000 by Seiko Corporation. Specifically, the cured film was cut into 2 mm x 3 cm and heated to 30 to 420 ° C. (heating rate 5 ° C./min) while weighting 10 g / min using a thermomechanical measuring device manufactured by Seiko TMA / SS6000. It was. The inclination of the elongation rate of the cured film between 100-200 degreeC at that time was measured, and it was set as CTE.

The case where CTE was 30 ppm / K or less was A (especially good), and the case where C was greater than 30 ppm / K and 45 ppm / K or less was B (good), and the case where CTE was larger than 45 ppm / K was C (not good).

The glass transition temperature was calculated | required from the inflection point of a thermal expansion coefficient at the temperature increase rate of 5 degree-C / min using the TMA / SS6000 made by Seiko Instool.

Mechanical strength (elastic modulus, elongation at break, and breaking strength) was determined from a tensile test using Shimadzu Corporation's Autograph AGS-100NH.

The modulus of elasticity was set to A (especially good) of 5.5 GPa or less, and larger than 5.5 GPa and B of 6.0 GPa or less and C (not good) of 6.0 GPa or less.

(Evaluation of drug resistance)

The obtained cured film was immersed at 80 degreeC for 10 minutes in the solution of dimethyl sulfoxide: monoethanolamine = 30: 70, and the chemical liquid tolerance of the cured film was evaluated. A with no crack in the cured film and B with a crack were evaluated.

In addition, the change of the film thickness before and behind the evaluation test of chemical-resistance tolerance was made into A, ± 0.3 or more and ± 0.5 micrometer or less, B, and larger than ± 0.5 micrometer that C was less than +/- 0.3 micrometer.

Examples 2-8, Comparative Examples 1-5

Except having changed the amine, the acid, and these amounts as shown in Table 1, polyamic acid was synthesize | combined similarly to Example 1, the resin composition and the cured film were produced, and these evaluations were performed.

Amines 1-3 and acids 1-4 are as follows.

Amine 1: 1,4-diaminocyclohexane

Amine 2: 3, 3'-bis (trifluoromethyl) benzidan

Amine 3: p-phenylenediamine

Acid 1: 3, 3 ', 4,4'-biphenyltetracarboxylic acid

Acid 2: 3, 3 ', 4,4'-tetracarboxydiphenyl ether

Acid 3: cyclohexanetetracarboxylic dianhydride

The cured film obtained in Examples 1-8 showed the favorable transmittance | permeability even after heat processing at 300 degreeC or more high temperature, CTE was small, birefringence was small, and the elasticity modulus was also small. It was found that the polyimide precursor of the present invention provides a cured film that satisfies all of transparency, CTE and mechanical strength.

Moreover, it turned out that all the cured films obtained in Examples 1-8 are excellent in chemical liquid tolerance.

On the other hand, when 3,3 ', 4,4'-tetracarboxydiphenyl ether was not included like Comparative Example 1, the elastic modulus and birefringence were increased.

In addition, as in Comparative Example 2, when 3,3 ', 4,4'-biphenyltetracarboxylic acid was not used, the CTE increased.

In addition, like Comparative Examples 3 to 5, 1,4-diaminocyclohexane, 3,3 ', 4,4'-biphenyltetracarboxylic acid and 3,3', 4,4'-tetracarboxydiphenyl ether When not using the polyimide precursor obtained by the combination of these, the cured film obtained could not satisfy all of transparency, CTE, mechanical property, and birefringence.

Industrial availability

The polyimide molded body of this invention can be used as a display base material, a protective film, etc.

While the embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will be aware of these exemplary embodiments and / or examples without departing substantially from the novel teachings and effects of the present invention. It is easy to make many changes to the. Therefore, many of these modifications are included within the scope of the present invention.

All the content of the document described in this specification and the Japanese application specification which becomes the basis of Paris priority of this application is used here.

Claims (13)

A polyimide precursor which is a copolymer having a structural unit represented by the following formulas (I) and (II), wherein the molar ratio of the structural unit represented by the formula (I) is less than 50 mol%.
[Tue 1]

The resin composition which has a polyimide precursor of Claim 1. The method of claim 2,
Resin composition containing an organic solvent. The method according to claim 2 or 3,
Resin composition for transparent substrate formation of a display apparatus. The polyimide obtained by heating the polyimide precursor of Claim 1. The manufacturing method of the polyimide molded body containing the process of apply | coating and drying the resin composition of Claim 2 on a base material, and forming a resin film, and the process of heat-processing the resin film after the said drying. The polyimide molded body obtained by the manufacturing method of Claim 6. The transparent substrate which consists of a polyimide molded body of Claim 7. The protective film which consists of a polyimide molded body of Claim 7. The electronic component which has a transparent substrate of Claim 8, or the protective film of Claim 9. The display apparatus which has a transparent substrate of Claim 8, or the protective film of Claim 9. The solar cell module which has a transparent substrate of Claim 8, or the protective film of Claim 9. delete