JP2017069200A - Manufacturing method of functional layer-attached polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method to obtain a functional layer-attached polyimide film by using a polyimide film which is low in linear expansion, superior in flatness, and which is less in outgassing even at a high temperature and superior in heat resistance.SOLUTION: A method for manufacturing a functional layer-attached polyimide film comprises the steps of: forming a functional layer on a polyimide film of a polyimide laminate arranged by laminating a base material and the polyimide film; and peeling the polyimide film together with the functional layer from the base material. In the method, the polyimide film is formed by performing a thermal treatment of polyamic acid within 60 minutes, and it has a glass transition temperature higher than 400°C, of which the temperature when the weight decrease rate is 0.3 mass% in a nitrogen atmosphere is 500°C or higher.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polyimide film with a functional layer using a polyimide film used as a support substrate for forming a functional layer of a display device or the like.

  Organic EL devices used for various displays, including large displays such as televisions and small displays such as mobile phones, personal computers, and smartphones, are generally thin film transistors (hereinafter TFT) on a glass substrate that is a supporting substrate. Further, an electrode, a light emitting layer, and an electrode are sequentially formed thereon, and these are hermetically sealed with a glass substrate, a multilayer thin film, or the like. The structure of the organic EL device includes a bottom emission structure that extracts light from the glass substrate side that is the support base material, and a top emission structure that extracts light from the opposite side of the glass substrate that is the support base material. It has been. A transparent material is required for the bottom emission TFT substrate, but a non-transparent material may be used for the top emission TFT substrate.

  By replacing the supporting base material of such an organic EL device with a resin from a conventional glass substrate, the organic EL device can be made thin, light and flexible, and the application of the organic EL device can be further expanded. However, since resin is generally inferior in dimensional stability, transparency, heat resistance, moisture resistance, film strength and the like as compared with glass, various studies have been made.

  For example, Patent Document 1 relates to a polyimide useful as a plastic substrate for flexible display and an invention relating to the precursor thereof, and a polyimide obtained by casting a polyimide precursor solution having a specific structure on an inorganic substrate, drying and imidizing. It discloses a laminate composed of a film and an inorganic substrate, and reports high light transmittance and low outgassing. However, since the thermal expansion coefficient (CTE) of the polyimide obtained here exceeds 40 ppm / K, the difference from the thermal expansion coefficient of the glass substrate is large. It becomes difficult to obtain an organic EL device having excellent shape stability, such as peeling and cracking.

  Patent Document 2 and Patent Document 5 relate to an invention relating to a polyimide precursor resin composition for forming a flexible device substrate such as a display device and a light receiving device that are peeled from a carrier substrate, and have a glass transition temperature of 300 ° C. or higher. And exhibiting a coefficient of thermal expansion of 20 ppm / K or less. However, there is a problem that the heat treatment time is as long as 1 hour or more and the productivity is low.

  In the organic EL production LTPS process, it is generally necessary to apply a high temperature of 450 ° C. If the material is pyrolyzed, the device becomes contaminated and unusable. In the process, it is very important that there is no outgassing.

  The organic EL device has low resistance to moisture, and the characteristics of the EL element that is the light emitting layer are degraded by moisture. Therefore, when a resin is used as the supporting base material, a resin having a low moisture absorption rate is preferred in order to prevent moisture and oxygen from entering the organic EL device. In general, an inorganic material typified by silicon oxide or silicon nitride is used as the organic EL substrate, and their thermal expansion coefficient (CTE) is usually 0 to 10 ppm / K. On the other hand, since a general polyimide has a CTE of greater than 10 ppm / K, if the polyimide is simply applied to a support substrate of an organic EL device, warping or cracking occurs due to thermal stress, or the polyimide peels off. Problems may occur. Patent Document 6 uses naphthalene tetracarboxylic dianhydride (NTCDA), but its thermal expansion coefficient is larger than 20 ppm / K, and warping may occur.

  In such a process, the laminate is required to have high heat resistance that can withstand steps such as vapor deposition and sputtering, and smoothness and low warpage for good handling. That is, the polyimide film of the laminate needs to have high heat resistance and a linear expansion coefficient comparable to that of glass. In addition, the linear expansion coefficients of soda-lime glass and alkali-free glass generally used as a glass substrate are about 8 to 9 ppm / ° C. and about 3 to 5 ppm / ° C., respectively.

  On the other hand, a method is known in which a polyimide precursor solution is cast on an inorganic substrate and thermal imidization is performed to obtain a laminate (Patent Document 3). In addition, it has been reported that a polyimide film having a low linear expansion coefficient is directly laminated on an inorganic substrate (Patent Document 4), but the process takes one hour or more, which increases the cost.

  Considering the above points, when replacing the support substrate for the display device from the glass substrate to the resin substrate, it is necessary to satisfy at least the characteristics of low CTE, high heat resistance and low outgas at the same time. There has been no resin substrate that can produce a material that satisfies all of these requirements.

JP2012-40836A JP 2010-202729 A Japanese Unexamined Patent Publication No. 64-774 JP 2012-35583 A Japanese Patent Laying-Open No. 2015-93915 Japanese Patent No. 4642664

  An object of the present invention is to provide a method for obtaining a polyimide film with a functional layer using a polyimide film having low linear expansion, excellent flatness, and excellent heat resistance without generation of outgas even at high temperatures.

  As a result of intensive studies, the inventors of the present invention have made the polyimide film heat-treat the polyamic acid within 60 minutes, so that the glass transition temperature is higher than 400 ° C., and the temperature of 0.3 mass% weight reduction rate in the nitrogen atmosphere is 500. The present inventors have found that a polyimide film having a temperature of at least ° C. can be obtained, and more preferably using a combination of an acid anhydride having a specific structure and a diamine.

That is, the gist of the present invention is as follows.
(1) A method for producing a polyimide film with a functional layer, wherein a functional layer is formed on a polyimide film of a polyimide laminate in which a substrate and a polyimide film are laminated, and the polyimide film is peeled off from the substrate together with the functional layer. The polyimide film is formed by heat-treating polyamic acid within 60 minutes, the glass transition temperature is higher than 400 ° C., and the temperature of 0.3 mass% weight reduction rate in the nitrogen atmosphere is 500 ° C. or higher. The manufacturing method of the polyimide film with a functional layer characterized.

（式中、Arは芳香環を1個以上有する2価の有機基である。） (2) The manufacturing method of the polyimide film with a functional layer of said (1) in which a polyimide film contains 10 mol% or more of structural units represented by following General formula (1).

(In the formula, Ar is a divalent organic group having one or more aromatic rings.)

(3) The above (1), wherein the polyimide film is obtained by reacting naphthalenetetracarboxylic dianhydride or biphenyltetracarboxylic dianhydride with phenylenediamine at a temperature of -20 ° C to 60 ° C. Or the manufacturing method of the polyimide film with a functional layer of (2).

(4) The above (1) to (3), wherein the polyimide film has a thermal expansion coefficient smaller than 10 ppm / K in a temperature range of 100 ° C. to 250 ° C. and does not contain an —OC═N— functional group. ) Any one of the manufacturing method of the polyimide film with a functional layer.

(5) Polyimide film is coated on a substrate with a polyamic acid solution obtained by reacting naphthalenetetracarboxylic dianhydride and biphenyltetracarboxylic dianhydride with phenylenediamine in the presence of an organic solvent, and the solvent is removed. Then, the method for producing a polyimide film with a functional layer according to any one of the above (1) to (4), which is obtained by reacting at a temperature of 110 ° C. to 380 ° C. and imidizing.

(6) The method for producing a polyimide film with a functional layer according to any one of the above (1) to (5), wherein the substrate comprises an inorganic substrate.

(7) The functional layer is a display element, a light emitting element, a circuit, a conductive film, a metal mesh, a hard coat film, or a gas barrier film, and the polyimide film with a functional layer according to any one of the above (1) to (6) Manufacturing method.

  According to the present invention, the manufactured polyimide film has high heat resistance, and since it emits less outgas in the high-temperature treatment process, it is suitable as a support substrate for display devices and the like, and can be reacted in a shorter time. Since a polyimide film excellent in productivity can be provided, it can be suitably used as a flexible substrate for forming a functional layer such as a display element, a light emitting element, a circuit, a conductive film, a metal mesh, a hard coat film, or a gas barrier film. .

  The polyimide film used in the present invention is a polyimide film having a glass transition temperature higher than 400 ° C. and a 0.3 mass% weight reduction rate in a nitrogen atmosphere being 500 ° C. or higher.

  In the present invention, a polyimide film can be obtained by the following method. That is, a reaction of tetracarboxylic dianhydride and diamine, which is known as a general production method, makes a polyimide polyamic acid (also called polyamic acid) as a polyimide by a ring-closing reaction by heat treatment. The method can be used.

  In order to produce the polyimide film with a function of the present invention, a polyimide containing 10 mol% or more of the structural unit of the general formula (1) is preferably used.

  As tetracarboxylic dianhydride used here, the tetracarboxylic dianhydride which has a naphthalene ring is used suitably from a heat resistant viewpoint. Specifically, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetra Carboxylic dianhydrides are listed, but from the viewpoint of high heat resistance and low thermal expansion coefficient, naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA), which is a structural unit of the general formula (1). Is particularly preferred. These naphthalene-2,3,6,7-tetracarboxylic dianhydrides (NTCDA) can be used in combination with other aromatic tetracarboxylic dianhydrides. It is good to use in mol% or more, Preferably it is 10-70 mol%. If it is less than 10 mol%, the effect of heat resistance is not sufficient, and if it exceeds 70 mol%, the film tends to be brittle.

  In the manufacturing method of this invention, it is preferable to use together with other tetracarboxylic dianhydrides for the purpose of giving a polyimide film strength and flexibility. Examples of such tetracarboxylic dianhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, cyclotetracarboxylic dianhydride, phenylenebis (trimellitic acid monoester anhydride), 4,4′-oxydiphthalic dianhydride, benzophenone-3,4,3 ′, 4′-tetracarboxylic dianhydride, diphenylsulfone-3,4,3 ′, 4′-tetracarboxylic dianhydride, 4,4 '-(2,2'-hexafluoroisopropolyden) diphthalic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic Although there are acid dianhydrides, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is particularly preferable because a polyimide film having a low thermal expansion coefficient can be obtained.

  The diamine used for the synthesis of the polyimide having the structural unit represented by the general formula (1) is an aromatic diamine having one or more aromatic rings (Ar). The aromatic diamine is not particularly limited as long as it is an aromatic diamine that gives the structural unit represented by the general formula (1). For example, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4,4'-methylenedi-o-toluidine, 4,4'- Methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3, 3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis [4- ( 4-aminophenoxy) phenyl] propane 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diamino Diphenyl ether, 3,3-diaminodiphenyl ether 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, benzidine, 3,3′-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p-terphenyl, 3,3'-diamino-p-terphenyl, bis (p -β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1- Dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene- 2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5 -Diamino-1,3,4-oxadiazole, piperazine and the like.

  Of these, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 2,4-toluenediamine, m-phenylenediamine, preferably having one aromatic ring P-phenylenediamine is used, but p-phenylenediamine is preferably used from the viewpoint of fast reaction and low thermal expansion.

  In the production method of the present invention, the polyamic acid, which is a precursor of polyimide, uses the aromatic diamine component and the tetracarboxylic dianhydride component shown above in a molar ratio of 0.9 to 1.1, in an organic polar solvent. It can be produced by a known method of polymerization. That is, after dissolving an aromatic diamine in an aprotic amide solvent such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone under a nitrogen stream, tetracarboxylic dianhydride is added, and the mixture is added at room temperature. It can be obtained by reacting for about 4 hours. At this time, the molecular terminal may be sealed with an aromatic monoamine or an aromatic dicarboxylic acid anhydride. Other examples of the solvent include dimethylformamide, 2-butanone, diglyme, xylene, γ-butyllactone, etc., and these can be used alone or in combination of two or more.

  Next, the polyamic acid obtained as described above is imidized by a thermal imidization method or a chemical imidization method to obtain a polyimide film. Thermal imidation is usually performed on an arbitrary substrate such as glass, metal, resin, etc. using an applicator, pre-dried at a temperature of 150 ° C. or lower for 2 to 58 minutes, and then for solvent removal and imidization. The heat treatment is performed at a temperature of about ~ 360 ° C for about 2 to 30 minutes. The preheating treatment and the heat treatment may be performed continuously. In chemical imidization, a dehydrating agent and a catalyst are added to polyamic acid, and chemical dehydration is performed at 30 to 60 ° C. A typical dehydrating agent is acetic anhydride, and a catalyst is pyridine.

  Here, the present inventors have empirically completed imidization in a relatively short time by selecting a combination of tetracarboxylic acid and aromatic diamine, which are highly soluble, and a solvent having excellent solubility and drying properties. It has been found that heat treatment including preheating can be performed within 60 minutes, preferably within 30 minutes, more preferably within 10 minutes.

  The degree of polymerization of the polyamic acid and the polyimide is 1 to 10 as the reduced viscosity of the polyamic acid solution, and preferably in the range of 3 to 7. The reduced viscosity (ηsp / C) is measured using an Ubbelohde viscometer in N, N-dimethylacetamide at 30 ° C. and a concentration of 0.5 g / dL, and can be calculated by (t / t0-1) / C. it can. The molecular weight of the polyamic acid can be determined by the GPC method. The preferred molecular weight range (polystyrene conversion) of the polyamic acid is preferably in the range of 15,000 to 250,000 in terms of number average molecular weight and 30,000 to 800,000 in terms of weight average molecular weight, but these are guidelines and all polyimides outside this range are used. That doesn't mean you can't. The molecular weight of polyimide is also in the same range as the molecular weight of its precursor.

In the production method of the present invention, the polyimide film preferably has a thermal expansion coefficient smaller than 10 ppm / K in a temperature range of 100 ° C. to 250 ° C. and does not contain a —O—C═N— functional group.
When the coefficient of thermal expansion in the temperature range of 100 ° C. to 250 ° C. is smaller than 10 ppm / K, a functional layer-equipped polyimide film having a small warpage due to thermal stress can be obtained.
Further, by not using a monomer having —O—C═N— functional group such as 5-amino-2- (4-aminophenyl) benzoxazole and 4-amino-2- (4-aminophenyl) benzoxazole, Decomposition hardly occurs, and a flexible polyimide film with a functional layer can be obtained.

  Moreover, in the manufacturing method of this invention, a polyimide film can also mix | blend and use various fillers and additives as needed in the range which does not impair the objective of this invention. For example, inorganic fine particles such as silica, alumina, boron nitride, and aluminum nitride may be added for the purpose of improving slipperiness and thermal conductivity.

  In the production method of the present invention, after applying the polyamic acid on the base material as described above, drying or heat treatment, or applying and drying the resin solution completed until imidization in the liquid phase, A polyimide laminate can be obtained by pasting a separately prepared polyimide film on another substrate. From the viewpoint of production efficiency, it is desirable that imidization is performed on the substrate as described above to obtain a laminate as it is.

  Moreover, you may make it the polyimide film with a function obtained by the manufacturing method of this invention consist of multiple layers of polyimide. In the case of a single layer, it is preferable to have a thickness of 3 μm to 50 μm. On the other hand, in the case of a plurality of layers, the main polyimide layer may be a polyimide film having the above thickness. Here, the main polyimide layer refers to a polyimide layer that occupies the largest proportion of the thickness among a plurality of polyimide layers, preferably 3 μm to 50 μm, more preferably 4 μm to 30 μm. is there.

  The polyimide laminate obtained by the production method of the present invention can form elements, layers and the like having various functions on the polyimide film surface of the laminate. For example, a display device such as a liquid crystal display device, an organic EL display device, and electronic paper, and may include components of the display device such as a color filter. In addition, the display device includes an organic EL lighting device, a touch panel device, a conductive film laminated with ITO, a gas barrier film that prevents permeation of moisture, oxygen, and the like, and components of a flexible circuit board. Various functional devices used are also included. That is, the functional layer referred to in the present invention is not only a component such as a liquid crystal display device, an organic EL display device, and a color filter, but also an organic EL lighting device, a touch panel device, an electrode layer or a light emitting layer of the organic EL display device, A gas barrier film, an adhesive film, a thin film transistor (TFT), a wiring layer of a liquid crystal display device, or a combination of two or more types such as a transparent conductive layer is also included.

  In addition, the formation method of the functional layer is appropriately set according to the target device, but in general, after forming a metal film, an inorganic film, an organic film, etc. on the polyimide film, It can be obtained by a known method such as patterning into a predetermined shape or heat treatment as required. That is, the means for forming these display elements is not particularly limited, and is appropriately selected, for example, sputtering, vapor deposition, CVD, printing, exposure, immersion, etc. If necessary, in a vacuum chamber, etc. These process processes may be performed. The base material and the polyimide film may be separated immediately after the functional layer is formed through various process treatments. For example, the base material and the polyimide film may be integrated with the base material for a certain period of time, for example, immediately before being used as a display device. It may be separated and removed.

  After forming the functional layer, the polyimide film is peeled off from the substrate together with the functional layer. When the polyimide film is peeled from the substrate together with the functional layer, the retardation increases when the polyimide film is stretched. For this reason, the method of peeling so that the stress concerning a polyimide film in the case of peeling becomes small is preferable.

  In order to prevent the stretching of the polyimide film, another layer is formed on the substrate, the polyimide film is formed thereon, the functional layer is formed thereon, and then the polyimide film is bonded to the other layer and the function. A method in which the entire layer is peeled and the stress necessary for peeling is dispersed in the other layers is preferable. This is particularly effective when the polyimide film is thin. In this case, including the other layers, it is regarded as a polyimide film according to the production method of the present invention. Examples of the method for forming the other layer include bonding of a resin film or a metal foil with an adhesive, coating, vapor deposition, and the like.

  Furthermore, as a method for facilitating peeling of the polyimide film from the substrate and preventing stretching, other known methods can be applied. For example, in Japanese Translation of PCT International Publication No. 2007-512568, a yellow film such as polyimide is formed on glass, then a thin film electronic element is formed on the yellow film, and then the UV laser light is irradiated to the bottom surface of the yellow film through the glass. Discloses that the glass and the yellow film can be peeled off. According to this method, since the polyimide film is separated from the glass by UV laser light, no stress is generated at the time of peeling, which is one of the preferable methods for the peeling process of the present invention. However, it is also disclosed that, unlike a yellow film, a transparent plastic does not absorb UV laser light, and therefore it is necessary to previously provide an absorption / release layer such as amorphous silicon under the film.

  Japanese Patent Application Publication No. 2012-511173 discloses the use of a laser having a spectrum in the range of 300 to 410 nm in order to separate the glass and the polyimide film by irradiation with UV laser light. By the way, as a peeling method, after irradiating a laser from the glass side and separating the resin base material provided with the display part from the glass, a release layer is applied to a glass substrate and formed, and then polyimide is formed on the release layer. After the resin is applied and the manufacturing process of the organic EL display device is completed, the polyimide film is peeled from the release layer, the surface of the inorganic layer is treated with a coupling agent, and then the coupling agent is patterned by UV irradiation or the like. Examples of the method include performing a treatment to form a laminate having a good adhesion portion and an easy peel portion having different peel strengths, and then peeling the laminate.

  Since the wavelength of light emitted from the light emitting layer of the organic EL device is mainly 440 nm to 780 nm, the average transmittance in this wavelength region is at least 80% or more as a support substrate used in the organic EL device. Is required. On the other hand, when the glass and polyimide film are peeled off by irradiation with the UV laser light described above, if the transmittance at the wavelength of the UV laser light is high, it is necessary to provide an absorption / peeling layer under the film, This reduces productivity. In order to perform peeling without providing an absorption / peeling layer, it is necessary that the polyimide film itself absorbs laser light sufficiently, and the transmittance of the polyimide film at 400 nm is preferably 60% or less, Preferably it is 40% or less.

In order to prevent moisture and oxygen from entering the organic EL device, a gas barrier layer may be formed on the polyimide film. In this case, the gas barrier layer and the polyimide film according to the production method of the present invention are considered. You may form in a single-piece | unit polyimide film and may form in the laminated body of base materials, such as glass and metal foil, and a polyimide film. A known gas barrier layer can be used, but as a gas barrier layer having a barrier property against oxygen, water vapor and the like, silicon oxide, aluminum oxide, silicon carbide, silicon oxycarbide, silicon carbonitride, silicon nitride, silicon nitride oxide, etc. An inorganic oxide film is preferably exemplified, and may be composed of only one kind of composition, or a film in which two or more kinds of compositions are confused may be selected.

  The outline of the manufacturing method will be described below using a bottom emission organic EL display device as a functional layer as a representative example.

  A gas barrier layer is provided on the resin substrate on which the functional layer is formed so that moisture and oxygen can be prevented from permeating. Next, a circuit configuration layer including a thin film transistor (TFT) is formed on the upper surface of the gas barrier layer. In this case, in the organic EL display device, an LTPS-TFT having a high operation speed is mainly selected as the thin film transistor. In this circuit configuration layer, an anode electrode made of, for example, an ITO (Indium Tin Oxide) transparent conductive film is formed on each of the plurality of pixel regions arranged in a matrix on the upper surface thereof. Further, an organic EL light emitting layer is formed on the upper surface of the anode electrode, and a cathode electrode is formed on the upper surface of the light emitting layer. This cathode electrode is formed in common in each pixel region. Then, a gas barrier layer is formed again so as to cover the surface of the cathode electrode, and a sealing substrate is installed on the outermost surface for surface protection. It is desirable from the viewpoint of reliability that a gas barrier layer for preventing moisture and oxygen from permeating is laminated on the surface of the sealing substrate on the cathode electrode side. The organic EL light-emitting layer is formed of a multilayer film (anode electrode-light-emitting layer-cathode electrode) such as a hole injection layer-hole transport layer-light-emitting layer-electron transport layer. Since it deteriorates due to moisture and oxygen, it is generally formed by vacuum deposition, and it is generally formed continuously in vacuum including electrode formation.

  Next, an outline of a touch panel used as input means of a display device such as a liquid crystal display device or an organic EL display device will be described. As described above, in addition to the reduction in thickness and weight of the display device, the progress of flexibility has been remarkable. However, the touch panel installed on the display device has been actively studied for reduction in thickness, weight, and flexibility.

  The main methods of touch panels are roughly classified into a method for detecting a change in light and a method for detecting a change in electrical characteristics. As a method for detecting a change in electrical characteristics, a resistance film method and a capacitive coupling method are known. In addition, there are two types of capacitive coupling methods: surface type and projection type, but projection type from the viewpoint of being suitable for multi-touch recognition (multi-point recognition), which has become an indispensable function for smartphones and the like. Has attracted attention, and the outline of the production method will be described below.

  The projected capacitive coupling type touch panel is provided with two electrode rows (first and second electrodes) in the vertical and horizontal directions, and by measuring the change in capacitance of the electrode when the finger touches the screen, the touch position can be determined. It can be detected precisely. The specific structure is a structure in which a first substrate on which a first electrode is formed and a second substrate on which a second electrode is formed are joined via an insulating layer (dielectric layer). Thinning, weight reduction, and flexibility can be realized by replacing the substrate on which the electrode is formed with a flexible resin substrate from the conventional glass substrate. In addition, the first electrode and the second electrode are formed on one substrate to further reduce the thickness and weight.

  Hereinafter, the contents of the present invention will be described more specifically based on examples and the like, but the present invention is not limited to the scope of these examples.

  First, the abbreviations of monomers and solvents for use in producing a polyimide film, and various physical property measurement methods and conditions in the examples are shown below.

DMAc: N, N-dimethylacetamide
BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride
NTCDA: 2,3,6,7-naphthalenetetracarboxylic dianhydride
p-PDA: Paraphenylenediamine
4,4'-DAPE: 4,4'-diaminodiphenyl ether
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl Base material: Glass substrate (Corning, 0.7 mm thickness)

[Coefficient of thermal expansion (CTE)]
A polyimide film with a size of 3 mm x 15 mm is heated from 30 ° C to 280 ° C at a constant rate of temperature rise (20 ° C / min) while applying a 5.0 g load with a thermomechanical analysis (TMA) device TMA100 manufactured by SEIKO. The temperature is raised and then lowered to 30 ° C., a tensile test is performed in this temperature range, and the coefficient of thermal expansion (ppm / K) is calculated from the change in the elongation of the polyimide film in the temperature range from 250 ° C. to 100 ° C. It was measured.

[Glass transition temperature Tg]
Dynamics of polyimide film (10 mm x 22.6 mm) when heated at 5 ° C / min from 20 ° C to 500 ° C with a dynamic viscoelasticity measurement (DMA) device RSA3 manufactured by TI Instruments Japan The viscoelasticity was measured and the glass transition temperature Tg (tan δ maximum value) was determined.

[Weight reduction rate at 500 ° C (wt%)]
Measure the change in weight of a polyimide film weighing 10 to 20 mg under a nitrogen atmosphere when the temperature is raised from 30 ° C. to 550 ° C. at a constant speed using a thermogravimetric analysis (TG) device TG / DTA6200 manufactured by SEIKO. The weight reduction rate at 500 ° C. with respect to 200 ° C. was calculated with the weight at 200 ° C. being zero.

[Peelability]
When the polyimide film could be peeled off from the substrate without breaking or tearing, it was judged as “good”. Further, in the process of peeling, when breakage / tear occurred and peeling became impossible, it was judged as x.

[Film forming properties]
The time required to obtain a polyimide with good appearance without foaming by heat treatment from polyamic acid is rated as ◯ within 60 minutes, and foaming is visible on the appearance even if it takes less than 60 minutes, and strength In the case where the film was insufficient, the film was marked as Δ, and the film that was too brittle and could not be formed into a film was marked as x.

Synthesis example 1
Under a nitrogen stream, 8.0567 g of p-PDA was dissolved in 170 g of DMAc while stirring in a 100 ml separable flask. Subsequently, BPDA: 19.2533g was added to this solution. Ten minutes later, NTCDA: 2.0180 g was added. The mol% content of NTCDA was 10%. Thereafter, the solution was stirred at room temperature for 4 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous colorless polyamic acid solution was obtained, and it was confirmed that polyamic acid A having a high degree of polymerization was produced.

Synthesis Examples 2-4
Polymerization was performed in the same manner as in Synthesis Example 1 except that the composition was changed as shown in Synthesis Examples 2 to 4 in Table 1, and polyamic acids B, C, and D were obtained.

Synthesis Examples 5-9
Polymerization was performed in the same manner as in Synthesis Example 1 except that the composition was changed as shown in Synthesis Examples 5 to 9 in Table 2, and polyamic acids E, F, G, H, and I were obtained.

Example 1
DMAc was added to the polyamic acid A solution obtained above, and diluted so that the viscosity became 5000 cP. It was applied on a glass substrate having a thickness of 0.5 mm and 10 mm square using an applicator so that the film thickness after heat treatment was about 25 μm, and the temperature was raised from 90 ° C. to 400 ° C. over 30 minutes (heat treatment time 30 minutes) ), Polyimide was formed on the glass substrate, and a laminate A was obtained. Next, the polyimide film was peeled from the glass substrate to obtain polyimide film A. Table 3 shows the results of various evaluations of the obtained polyimide film A and laminate A.

Examples 2-3
Laminated bodies B to C and polyimide films B to C according to Examples 2 to 3 in the same manner as Example 1 except that the resin was changed to polyamic acids B and C as shown in Examples 2 to 3 of Table 3. Was made. The evaluation results are also shown in Table 3.

Comparative Example 1
A laminate D and a polyimide film D according to Comparative Example 1 were produced in the same manner as in Example 1 except that the resin was changed to polyamic acid D as shown in Table 3. The evaluation results are also shown in Table 3.

Comparative Examples 2-6
As shown in Table 3, laminates E, F, G, H and I according to Comparative Examples 2 to 6 were prepared in the same manner as in Example 1 except that the resin was changed to polyamic acids E, F, G, H and I. And polyimide films E, F, G, H, and I were prepared. The evaluation results are also shown in Table 3.

* PAc酸：ポリアミック酸、PI：ポリイミドフィルム

* PAc acid: Polyamic acid, PI: Polyimide film

Example 4
Example 4 is an example for producing a polyimide film with a functional layer in which an organic EL display element is attached on a polyimide film. First, in the same manner as in Example 1, DMAc was added to the polyamic acid A solution obtained above, and diluted so that the viscosity became 5000 cP. It was applied on a glass substrate having a thickness of 0.5 mm and 10 mm square using an applicator so that the film thickness after heat treatment was about 10 μm, and the temperature was raised from 90 ° C. to 400 ° C. over 30 minutes (heat treatment time 30 minutes) ), A polyimide film A was formed on the glass substrate to obtain a polyimide laminate A. A gas barrier layer was provided on the polyimide film A so as to prevent moisture and oxygen from passing through. Next, a circuit configuration layer including a thin film transistor (TFT) was formed on the upper surface of the gas barrier layer. In this case, in the organic EL display device, LTPS-TFT having a high operation speed was selected as the thin film transistor. An anode electrode made of a transparent conductive film made of ITO (Indium Tin Oxide) was formed on each of the circuit constituent layers on each of the plurality of pixel regions arranged in a matrix on the upper surface. Further, an organic EL light emitting layer was formed on the upper surface of the anode electrode, and a cathode electrode was formed on the upper surface of the light emitting layer. This cathode electrode is formed in common in each pixel region. Then, a gas barrier layer is formed again so as to cover the surface of the cathode electrode, and a sealing substrate is installed on the outermost surface for surface protection. The organic EL light emitting layer is formed of a multilayer film (anode electrode-light emitting layer-cathode electrode) such as a hole injection layer-hole transport layer-light emitting layer-electron transport layer, etc. Since it deteriorates due to oxygen and oxygen, it was formed by vacuum deposition, and was continuously formed in a vacuum including electrode formation.

Example 5
Example 5 is an example of manufacturing a polyimide film with a functional layer in which a projected capacitive coupling type touch panel is attached on a polyimide film. Except for using polyamic acid B, a polyimide film B was formed on a glass substrate in the same manner as in Example 4 to obtain a polyimide laminate B. On the polyimide film B, two electrode rows (first and second electrodes) are provided vertically and horizontally, and by measuring the change in capacitance of the electrode when the finger touches the screen, the contact position is precisely determined. It can be detected. The specific structure is a structure in which a first substrate on which a first electrode is formed and a second substrate on which a second electrode is formed are joined via an insulating layer (dielectric layer). Thinning, weight reduction, and flexibility can be realized by replacing the substrate on which the electrode is formed with a flexible resin substrate from the conventional glass substrate. In addition, the first electrode and the second electrode are formed on one substrate to further reduce the thickness and weight.

As shown in Table 3, the polyimide films according to Examples 1 to 3 satisfying the production conditions of the present invention have a thermal expansion coefficient smaller than 10 ppm / k while maintaining heat resistance, and are neatly peeled from the support substrate. The film could be formed for a short time. Therefore, such a polyimide film is suitable as a supporting base material for forming a substrate for a vapor deposition mask and a fan-out wafer level package (FOWLP) in addition to a display device such as an organic EL display, organic EL lighting, electronic paper, and a touch panel. Can be used for
On the other hand, as shown in Table 3, those made of the polyimide film according to Comparative Example 1 that does not satisfy the production conditions of the present invention have a large coefficient of thermal expansion, and the laminate with glass may be warped. The film could not be formed due to foaming and was not suitable as a polyimide film for forming a functional layer of a display device or the like. What consists of the polyimide film which concerns on the comparative example 2 had a large weight reduction | decrease, and when forming functional layers, such as a display apparatus, there was a possibility of a contamination to a functional layer by outgas. Those made of the polyimide film according to Comparative Examples 3 to 5 were brittle and overwhelmingly lacked in strength as a film, and some physical properties could not be evaluated by a measuring instrument.

Claims (7)

  It is a manufacturing method of a polyimide film with a functional layer which forms a functional layer on a polyimide film of a polyimide laminate in which a substrate and a polyimide film are laminated, and peels the polyimide film from the substrate together with the functional layer. The polyamic acid is formed by heat treatment within 60 minutes, has a glass transition temperature higher than 400 ° C., and a 0.3 mass% weight loss rate in a nitrogen atmosphere is 500 ° C. or higher. A method for producing a polyimide film with a functional layer. The manufacturing method of the polyimide film with a functional layer of Claim 1 in which a polyimide film contains 10 mol% or more of structural units represented by following General formula (1).

(In the formula, Ar is a divalent organic group having one or more aromatic rings.)   The polyimide film is obtained by reacting naphthalenetetracarboxylic dianhydride or biphenyltetracarboxylic dianhydride with phenylenediamine at a temperature of -20 ° C to 60 ° C. A method for producing a polyimide film with a functional layer.   The polyimide film has a thermal expansion coefficient smaller than 10 ppm / K in a temperature range of 100 ° C to 250 ° C and does not contain -OC = N-functional group. Manufacturing method of polyimide film with functional layer.   After applying a polyamic acid solution obtained by reacting naphthalenetetracarboxylic dianhydride and biphenyltetracarboxylic dianhydride and phenylenediamine in the presence of an organic solvent on the substrate and removing the solvent, the polyimide film is It obtains by making it react at the temperature of 110 to 380 degreeC, and imidating, The manufacturing method of the polyimide film with a functional layer in any one of Claims 1-4 characterized by the above-mentioned.   The method for producing a polyimide film with a functional layer according to any one of claims 1 to 5, wherein the substrate comprises an inorganic substrate.   The method for producing a polyimide film with a functional layer according to claim 1, wherein the functional layer is a display element, a light emitting element, a circuit, a conductive film, a metal mesh, a hard coat film, or a gas barrier film.