TWI656026B - Polyimide laminate and method of producing the same - Google Patents

Abstract

The present invention provides a polyimide laminate having transparency, a polyimide membrane having excellent operability and dimensional stability, and capable of easily separating a polyimide membrane from a self-supporting substrate, and a method for producing the same.

The polyimide laminate system is provided with a supporting substrate on the back side of the polyimide layer, wherein the polyimide layer has a transmittance of more than 70% in a predetermined wavelength region; the interface of these layers is supported The surface of the substrate is formed of heat-resistant polyimide with a glass transition temperature Tg of 300 ° C or higher and a surface roughness Ra of 100 nm or less; the bonding strength between the supporting substrate and the polyimide layer is 1N / m or more 500N / m or less; and can separate the polyimide layer from the self-supporting substrate. In addition, the manufacturing method of the polyimide laminate is to apply a resin solution of polyamic acid while carrying a long supporting substrate in a roll-to-roll process to form a predetermined amount of imidization. The polyimide layer.

Description

Polyimide laminate and manufacturing method thereof

The present invention relates to a polyimide laminate and a method for manufacturing the same, and in particular, it relates to a polyimide laminate and a method for manufacturing the polyimide layer laminated on a supporting substrate through a polyimide layer having transparency.

Display devices such as liquid crystal display devices and organic EL display devices are used for various display applications such as large-sized displays such as televisions, and small displays such as mobile phones, personal computers, and smart phones. Among them, an organic EL display device is used as an example. After forming a thin-film transistor (hereinafter referred to as a TFT) on a glass substrate, the electrodes, light-emitting layers, and electrodes are sequentially laminated, and finally hermetically sealed with another glass substrate, a multilayer film, etc. Made.

Here, by replacing the glass substrate with a resin substrate, it is possible to achieve thinness, weight reduction, and flexibility, and it is possible to further expand the use of a display device. For example, Non-Patent Documents 1 and 2 propose organic EL display devices in which highly transparent polyimide is applied to a supporting substrate. However, in general, because resins have lower dimensional stability, transparency, heat resistance, moisture resistance, and gas barrier properties than glass, development of resins with properties equivalent to glass is currently underway.

For example, Patent Document 1 reports the invention of polyimide and its precursor that can be used as a plastic substrate for a flexible display, using a tetracarboxylic acid containing an alicyclic structure such as cyclohexylphenyltetracarboxylic acid. Polyamines that react with various diamines have excellent transparency and heat resistance.

On the other hand, the problems when the advantages of the resin substrate are touched are the operability and dimensional stability of the resin substrate itself. That is, when the resin substrate is formed into a thin film, while preventing occurrence of wrinkles and cracks, the position accuracy when forming a functional layer such as a TFT and an electrode is laminated, and the dimensional accuracy after forming a functional layer becomes Difficult to maintain. Here, Non-Patent Document 3 proposes a method of forming a predetermined functional layer and coating and fixing a resin substrate on glass by a method called EPLaR (Electronics on Plastic by Laser Release). A method of irradiating a side with a laser and forcibly separating a resin substrate having a functional layer from glass.

Furthermore, Non-Patent Document 4 proposes a method in which a polyamic acid solution is applied to a glass via a peeling layer to harden it, and after a predetermined functional layer is provided on the obtained polyimide substrate, Method for peeling a polyimide substrate from glass. In this method, a polyamic acid solution with a wider area than the release layer is applied, and the surrounding part of the cured polyimide substrate is directly fixed to the glass, so that the surrounding part remains on the glass and cut into The functional layer forms a polyimide substrate formed by separating the glass with the release layer in between.

These non-patent documents 3 and 4 use glass as a support substrate, and the resin substrate fixed to the glass forms a functional layer to ensure the operability and dimensional stability of the resin substrate. There are problems such as low productivity due to the special method used to separate the resin substrate from the glass. That is, in the method using the EPLaR process described in Non-Patent Document 3, it is not only time-consuming to separate the resin substrate from the glass, but also may adversely affect the surface characteristics of the resin substrate. In addition, in the method described in Non-Patent Document 4, in addition to an increase in the number of steps, an area that is not available for the resin substrate is generated and waste is caused. Therefore, it is strongly desired to develop the advantages of using resin substrates to promote the development of technologies used by industrial means.

In addition, Patent Documents 2 and 3 describe inventions related to a method for producing a polyurethane film, and disclose that each of the polyamide layers is coated with a polyamic acid on a polyimide layer of a metal foil having a predetermined polyimide layer. The solution is a method for producing a polyimide film which has been heat-treated and torn off the imidized polyimide, to suppress the appearance of wrinkles, cracks, and the like, but the polyimide film shown therein It is not transparent and does not describe any user who uses polyimide in a laminated state as a resin substrate.

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-231327

[Patent Document 2] Japanese Patent No. 4260530

[Patent Document 3] Japanese Patent Laid-Open No. 2011-56825

[Non-patent literature]

[Non-Patent Document 1] S. An et. Al., "2.8-inch WQVGA Flexible AMOLED Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates", SID2010 DIGEST, p706 (2010)

[Non-Patent Document 2] Oishi et. Al., "Transparent PI for flexible display", IDW ‘11 FLX2 / FMC4-1

[Non-Patent Document 3] E.I. Haskal et. Al. "Flexible OLED Displays Made with the EP LaR Process", Proc. Eurodisplay ’07, pp.36-39 (2007)

[Non-Patent Document 4] Cheng-Chung Lee et. Al. "A Novel Approach to Make Flexible Active Matrix Displays", SID10 Digest, pp.810-813 (2010)

Here, the present inventors have actively researched the use of a polyurethane film having excellent heat resistance and transparency as a resin substrate while ensuring handling properties (also referred to as handling) and dimensional stability. As a result, a polyimide laminate having a supporting base material on the back side of the transparent imidamine layer was found, and the surface of the supporting base material was formed by polyimide having predetermined characteristics. The self-supporting substrate separates the polyimide film including the polyimide layer, thereby completely solving the problems of the prior art, thereby completing the present invention.

Therefore, an object of the present invention is to provide a polyimide film having transparency as a resin substrate, at the same time, it has excellent operability and dimensional stability, and it is easy to separate the polyimide film from a self-supporting substrate. Lamidine laminates and methods of making same.

That is, the present invention is mainly as described below.

(1) A polyimide laminate, which is provided with a supporting substrate on the back side of the polyimide layer, characterized in that the polyimide layer has a transmittance of 70% or more in a wavelength region of 440 nm to 780 nm The surface of the support substrate at the interface between the polyimide layer and the support substrate is formed of a heat-resistant polyimide having a glass transition temperature Tg of 300 ° C or higher, and a surface roughness Ra of 100 nm or less. The bonding strength with the polyimide layer is 1N / m or more and 500N / m or less, and the polyimide film including the polyimide layer can be separated from the supporting substrate.

(2) The polyimide laminate as described in (1), wherein the polyimide layer includes a single layer or a plurality of layers, and at least a layer connected to the supporting substrate is a fluorinated polyimide.

(3) The polyimide laminate according to (1) or (2), wherein the heat-resistant polyimide of the supporting substrate is a polyimide having the following structural unit.

(4) The polyurethane laminate according to any one of (1) to (3), wherein the coefficient of thermal expansion of the polyurethane layer is 15 ppm / K or less.

(5) The polyimide laminate according to any one of (1) to (4), wherein the thickness of the polyimide layer is 3 μm or more and 50 μm or less, and the thickness of the supporting substrate is 10 μm or more 100 μm or less.

(6) The polyurethane laminate according to any one of (1) to (5), wherein the surface roughness Ra of the release surface of the polyurethane film after the self-supporting substrate is peeled off It is 100 nm or less.

(7) The polyurethane laminate according to any one of (1) to (6), which forms a predetermined functional layer on the surface side of the polyurethane layer, and then separates the supporting substrate on the back side And users.

(8) The polyurethane laminate according to any one of (1) to (7), which is further provided with an adhesive layer on the back surface side of the supporting substrate.

(9) A method for producing a polyimide laminate, which is a method for producing a polyimide laminate having a supporting substrate on the back side of the polyimide layer, which is characterized in that the glass transition temperature Tg is 300 The strip-shaped support substrate of the heat-resistant polyimide surface formed by the heat-resistant polyurethane having a surface roughness Ra of 100 nm or less and a surface roughness Ra of 100 nm or less is transported in a roll-to-roll process while the strip-shaped support substrate The polyimide resin solution is coated on the heat-resistant polyimide surface of the material, and each support substrate is heat-treated at 200 ° C or higher to polyimide the polyimide and attach to the support substrate. A polyimide layer having a transmittance of 70% or more in a wavelength range of 440nm to 780nm is formed on the polyimide layer, and the bonding strength between the supporting substrate and the polyimide layer is 1N / m or more and 500N / m or less. The supporting substrate separates a polyurethane film including a polyurethane layer.

(10) The method for producing a polyimide laminate as described in (9), wherein the heat treatment conditions of the polyamic acid are from a temperature lower than a maximum temperature of 20 ° C. to a maximum temperature when the heating is performed. The heating time in the high-temperature heating temperature zone is within 15 minutes.

(11) The method for producing a polyimide laminate as described in (9) or (10), wherein the heat-resistant polyimide forming the heat-resistant polyimide surface of the supporting substrate has the following structural unit Polyimide,

(12) A method for producing a polyimide membrane, characterized in that the polyimide layer is separated from the polyimide laminate obtained by the method described in any one of (9) to (11).

With the polyimide laminate of the present invention, a polyimide layer having excellent transparency and heat resistance is integrated with a predetermined supporting substrate, thereby ensuring workability, dimensional stability, and the like, and being easy to support itself. The base material is separated from the polyimide layer to form a polyimide film. Therefore, the polyimide film can be suitably used as a resin substrate. In addition, the polyurethane laminate of the present invention has high heat resistance of the laminate itself, which is not only suitable for high-temperature heat treatment processes, but also has flexibility by reducing thickness, and can also be applied to rolls. The method of using the roll process for transportation is suitable for manufacturing touch panels and display devices.

1‧‧‧Polyurethane layer

2‧‧‧ support substrate

3‧‧‧ functional layer

4‧‧‧ Adhesive layer

10‧‧‧Polyurethane laminate

11‧‧‧ Coating and heat treatment department

12‧‧‧ output structure

13‧‧‧ winding structure

14‧‧‧ roll structure on the output side

15‧‧‧Roll-up roll structure

Figures 1 (A) and (B) are cross-sectional views showing one aspect of the polyurethane laminate of the present invention.

Fig. 2 is a cross-sectional view showing another aspect of the polyimide laminate of the present invention (when the polyimide layer is plural).

FIG. 3 shows another aspect of the polyimide laminate of the present invention. (In the case where the supporting base material layer is plural layers) cross-sectional views.

FIG. 4 is a schematic diagram showing a roll-to-roll device for forming a polyurethane layer on a long support substrate.

Fig. 5 is a schematic diagram showing a long wheel-shaped supporting substrate.

The present invention is explained in detail below.

The polyimide laminate system of the present invention includes a polyimide layer and a supporting base material as necessary constituent members, and as shown in FIG. 1, a supporting base material 2 is provided on the back side of the polyimide layer 1. The thickness of the polyimide layer 1 in the polyimide laminate 10 is preferably 3 μm or more and 50 μm or less. When the thickness of the polyurethane layer 1 is less than 3 μm, when the layer is used as an insulating layer, not only may there be a fear of insufficient insulation performance, but also the rationality of the polyurethane film after being separated from the polyurethane laminate 10 It is also not good. On the other hand, when it exceeds 50 μm, the flexibility and transparency of the separated polyurethane film may be reduced. Although the thickness of the support substrate 2 is not particularly limited as long as it is easy to separate, it is preferably 10 μm or more and 100 μm or less. When the thickness of the support base material 2 is less than 10 μm, the supportability of the support base material 2 cannot be fully exerted, and the handling and handling properties may be reduced. When it exceeds 100 μm, the cost of the product is disadvantageous.

The polyimide laminate 10 of the present invention can easily separate the supporting substrate 2 and the polyimide layer 1. In the present invention, in order to exhibit such easy separation, it is preferable that one or both of the support substrate 2 and the polyurethane layer 1 use a specific member shown below.

First, the supporting substrate 2 used in the present invention will be described.

Examples of the supporting substrate 2 used in the present invention include a case where the supporting substrate 2 shown in FIG. 1 (A) includes a resin substrate, or a resin layer formed on a metal foil 2b as shown in FIG. 3. The composite substrate of 2a is not particularly limited as long as it shows a predetermined characteristic that it is easy to separate from the polyurethane layer 1. "Easy to be separated from the polyamide layer 1" refers to the one which is referred to as the supporting strength between the support substrate 2 and the polyurethane layer 1 in the range of 1N / m to 500N / m, but preferably 5N / m It is 300 N / m or more, more preferably 10 N / m or more and 200 N / m or less. By using this range as the peeling strength of the support substrate 2 and the polyurethane layer 1, it is possible to obtain appearance defects without wrinkles and cracks, and to give a transparent polyurethane film that can be industrially produced stably.聚 亚胺 mine laminated body 10.

The polyimide laminate 10 of the present invention can be used for manufacturing a touch panel, a display device, etc. At this time, it must have heat resistance. Therefore, in the case where the support substrate 2 includes a resin substrate, for example, a polyurethane substrate is preferred, and in the case where the support substrate 2 includes a composite substrate, a metal foil and a polymer substrate are used. Laminar laminates are better exemplified.

Here, at least the surface of the support base material 2 that becomes the interface with the polyamide layer 1 must be formed by a heat-resistant polyimide having a glass transition temperature Tg of 300 ° C. or higher. When the glass transition temperature Tg of the heat-resistant polyimide on the surface of the supporting substrate is less than 300 ° C, in addition to the heat resistance of the polyimide laminate 10 being reduced, the separation from the polyimide layer 1 may deteriorate. Fear. The surface roughness Ra of the heat-resistant polyimide surface must be 100 nm or less. When the surface roughness Ra exceeds 100 nm, the separation from the polyurethane layer 1 will still deteriorate, which will not only cause deformation during the separation of the polyurethane, but its transparency will also tend to decrease.

Next, the polyimide layer 1 constituting the polyimide laminate 10 of the present invention will be described.

The polyimide layer 1 of the polyimide laminate 10 of the present invention exhibits a transmittance of 70% or more in a wavelength region from 440 nm to 780 nm (in this specification, when this transmittance characteristic is satisfied, it is shown as transparency Person performance). Although the polyurethane layer 1 is directly disposed on the supporting substrate 2, the polyurethane layer 1 may include only a single layer, or may include, for example, a plurality of layers as shown in FIG. 2 ( 1a, 1b, 1c). When the polyimide layer 1 includes a plurality of layers, the above-mentioned transmittance is exhibited in the entire plurality of layers.

In the polyimide laminate 10 of the present invention, the surface of the polyimide layer 1 provided on the supporting base material, and the surface of the supporting base material 2 serving as an interface with the polyimide layer 1 are determined by respective orders. Made of polyimide.

Polyimide is generally obtained by polymerizing an acid anhydride and a diamine as a raw material, and is represented by the following general formula (1).

In the formula, Ar ₁ represents a tetravalent organic group, and Ar ₂ is a divalent organic group. However, from the viewpoint of heat resistance, it is preferred that at least one of Ar ₁ and Ar ₂ be an aromatic residue.

Here, as the acid anhydride of the polyimide raw material, representative examples thereof include pyromellitic dianhydride, 3,3 ', 4,4'-diphenyl ketone tetracarboxylic dianhydride, 2,2 ', 3,3'-diphenylketonetetracarboxylic dianhydride, 2,3,3', 4'-diphenylketonetetracarboxylic dianhydride, naphthalene-2,3,6,7- Tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic acid Acid dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5, 6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6- Dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloro Naphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3 ', 4,4 '-Biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,3 " , 4,4 ”-p-teretricarboxylic dianhydride, 2,2”, 3,3 ”-p-teretricarboxylic dianhydride, 2,3,3”, 4 ”-p- Ditriphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -propane Dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis ( 2,3-dicarboxyphenyl) fluorene dianhydride, bis (3,4-dicarboxyphenyl) fluorene dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1, 1-bis (3,4-dicarboxyphenyl) ethane dianhydride, fluorene-2,3,8,9-tetracarboxylic dianhydride, fluorene-3,4,9,10-tetracarboxylic dianhydride,苝 -4,5,10,11-tetracarboxylic dianhydride, 苝 -5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene- 1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyridine -2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4, 4'-oxydiphthalic dianhydride, etc. These can be used alone or in combination of two or more.

In addition, as the diamine as the raw material of the polyimide, representative examples include 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2, 4-Diaminotrimethylbenzene, 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-2,6-xylyleneamine, 4,4'-methylene- 2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminediamine Phenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'- Diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminodiphenylsulfide, 3,3'-diamine Diphenylsulfide, 4,4'-diaminodiphenylphosphonium, 3,3'-diaminodiphenylphosphonium, 3,3'-diaminodiphenyl ether, 4,4'- Diaminodiphenyl ether, 3,4'-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'-diamine Biphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p-bitriphenyl, 3,3'-diamino- P-bitriphenyl, bis (p-aminocyclohexyl) methane, bis (p-β-amino-third 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-third butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p- -Xylene-2,5-diamine, m-xylenediamine, p-xylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamine -1,3,4- Diazole, piperazine Etc. These can be used individually or in mixture of 2 or more types.

Among them, the heat-resistant polyimide constituting the surface of the supporting base material 2 that becomes the interface with the polyimide layer 1 must have a glass transition temperature Tg of 300 ° C. or higher, and may preferably include diphenyltetracarboxylic acid di Polyimide as the main component with the following structural units of anhydride and phenylenediamine, In particular, it may be polyimide containing the structural unit shown below as a main component.

The term "main component" as used herein means that the structural units constituting the heat-resistant polyimide account for 50 mol% or more, and preferably 80 mol% or more.

On the other hand, the polyimide layer 1 on the support substrate 2 in the polyimide laminate 10 of the present invention, when the above-mentioned preferred polyimide is used for the support substrate 2, if it is easy to separate Those who impart a transparent polyimide layer can be used without particular restrictions, but when the above-mentioned preferred polyimide is not used on the surface of the supporting substrate, or when it is desired to be more easily separated, the preferred one is the supporting substrate. Fluorine-containing polyimide is used as a layer adjacent to the material 2. This means that when the polyimide layer 1 includes a single layer, the polyimide is a fluorinated polyimide, and as shown in FIG. 2, when the polyimide layer includes a plurality of layers, The layer 1a adjacent to the heat-resistant polyimide on the surface of the substrate is a fluorinated polyimide.

The fluorinated polyimide refers to those having a fluorine atom in the polyimide structure, and at least one of the acid anhydride and the diamine of the polyimide raw material is a fluorinated group. Such a fluorine-containing polyimide is exemplified by Ar ₂ in the above-mentioned general formula (1) being one represented by the following general formula (2) or (3).

[Wherein, R ₁ to R ₈ in the general formula (2) or (3) are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group, or a fluorine-substituted Hydrocarbon group, at least one of R ₁ to R ₄ in the general formula (2) is a fluorine atom or a hydrocarbon group substituted with fluorine, and at least one of R ₁ to R ₈ in the general formula (3) is fluorine A hydrogen atom or a fluorine-substituted hydrocarbon group. ]

Preferable specific examples of R ₁ to R ₈ include -H, -CH ₃ , -OCH ₃ , -F, -CF ₃ and the like, and at least one substituent in the formula (2) or (3) may be- Either F or -CF ₃ .

Specific examples of Ar ₁ in the general formula (1) when forming a fluorinated polyimide include, for example, the following tetravalent acid anhydride residues.

When a fluorinated polyimide is formed, specific diamine residues imparted to Ar ₂ in the general formula (1) include, for example, the following.

The polyimide layer 1 preferably has high heat resistance and a thermal expansion coefficient of 15 ppm / K or less. Among the polyimide resins exemplified above, a polyimide resin having a ratio of 80 mol% or more is preferably represented by the following formula (4 ) Or (5).

The various polyimide-based polyamidic acids described above are obtained by imidization. Here, diamines and acid dianhydrides that are substantially equivalent to the raw materials can be obtained by reaction in an organic solvent. Polyamic acid resin solution. More specifically, after dissolving the diamine in an organic polar solvent such as N, N-dimethylacetamide under a stream of nitrogen, a tetracarboxylic dianhydride can be added and reacted at room temperature for about 5 hours. And get. Film thickness based on coating From the viewpoint of homogenization and mechanical strength of the obtained polyimide film, the weight average molecular weight of the obtained polyamic acid is preferably 10,000 to 300,000. Moreover, the preferable molecular weight range of a polyimide layer is also the same as the molecular weight range of a polyamic acid.

When polyimide is used as a polyimide having a structure of the general formula (4) or (5), other polyimide may be added in addition to the polyimide and having a maximum ratio of 20 mole%. In other words, there is no particular limitation, and general acid anhydrides and diamines can be used. Preferable acid anhydrides to be used include pyromelite dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 1,4-cyclohexanedicarboxylic acid, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, and the like, and diamines include 4,4'-diaminodiphenyl Hydrazone, trans-1,4-diaminocyclohexane, 4,4'-diaminocyclohexylmethane, 2,2'-bis (4-aminocyclohexyl) -hexafluoropropane, 2,2 '-Bis (trifluoromethyl) -4,4'-diaminobicyclohexane and the like.

The polyimide layer 1 thus obtained may be a single layer as described above, or may include a plurality of layers. Even when a plurality of layers are included, a polyamic acid that imparts transparency can be formed by appropriately selecting a raw material. The multiple layers of polyimide make the overall polyurethane layer transparent.

The polyimide film of the present invention is obtained by forming a polyimide layer 1 on a supporting substrate 2 and separating the polyimide layer by means such as peeling. It is preferable that the peeling surface of the imine film has a surface roughness Ra of 100 nm or less. When the surface roughness of this peeling surface becomes low, the surface on the support substrate 2 side can also become smooth. When a composite substrate using a metal foil and a resin is used as the support substrate 2 as an example, the metal foil is coated by a coating method. The resin solution that forms a polyamic acid is heat-treated to dry and / or harden, so that the surface roughness Ra of the heat-resistant polyimide surface becomes 100nm or less.

In the present invention, in addition to the polyimide laminate 10 laminated on the polyimide layer 1 on the supporting substrate 2, as shown in FIG. 1 (B), the polyimide laminate 10 can also be used here. A predetermined functional layer 3 is formed on the surface side of the polyimide layer 1 as a polyimide laminate. After such a polyurethane laminated system is separated from the supporting substrate on the back side, a polyurethane film with a functional layer is provided. Examples of the functional layer herein include display devices such as organic EL and liquid crystal displays, input devices such as touch panels, barrier layers for preventing gas or moisture from passing through, and transparent conductive films. In addition, the separation of the supporting substrate 2 after the predetermined functional layer 3 is formed may be any step after the functional layer is formed.

Furthermore, the polyurethane laminate 10 of the present invention is on the back side of the support substrate 2, that is, the surface of the support substrate 2 on the opposite side of the interface formed by the polyurethane layer 1 and the support substrate 2. It may further include an adhesive layer 4 containing epoxy resin, acrylic resin, and the like. Thereby, after the polyurethane laminate 10 is adhered to other members, the operation of separating only the polyurethane membrane or the polyurethane membrane with a functional layer can be performed.

Next, the manufacturing method of the polyimide laminated body of this invention is demonstrated in detail.

A preferred method for producing the polyimide laminate 10 according to the present invention is characterized by having a heat-resistant polyimide having a glass transition temperature Tg of 300 ° C. or higher and a surface roughness Ra of 100 nm or less. While the long support substrate 2 on the heat-resistant polyimide surface is transported in a roll-to-roll process, the fluorine-containing polyamine resin is coated on the heat-resistant polyimide surface of the long support substrate 2. Resin solution, and each supporting substrate 2 Polyimide is heat-treated to aminate the polyimide, in addition to forming a polyimide layer 1 having a transmittance of 70% or more in a wavelength range of 440 to 780 nm on the support substrate 2, and the support substrate 2 and The bonding strength of the polyurethane layer 1 is 1 N / m to 500 N / m, and the polyurethane film including the polyamide layer 1 can be separated from the supporting substrate 2.

That is, the preferred method for manufacturing the polyurethane laminate 10 according to the present invention is a roll-to-roll process. Therefore, in addition to having a long shape, the supporting substrate 2 has a glass transition temperature Tg of 300 ° C. Above, the heat-resistant polyimide surface formed by the heat-resistant polyimide having a surface roughness Ra of 100 nm or less. In the roll-to-roll manufacturing process, the support base material 2 is prepared in a rolled state, and a part of the support base material 2 is pulled out and supplied as the support base material 2. Moreover, it is preferable that the polyimide system which gives a heat resistant polyimide surface is the same as what is described in the said invention of the polyimide laminated body. Furthermore, it has the following advantages: the support material has conductivity, or, for the polyurethane layer, when a conductive layer is provided on the back of the opposite side, the film is pulled out roll-to-roll to prevent the layer from being wound. Charged by static electricity.

Thereby, a resin solution of a polyamic acid precursor of a polyimide precursor is coated on the heat-resistant polyimide surface of the supplied long support substrate 2. It is preferable to use the above-mentioned fluorine-containing polyamic acid as the polyamino acid.

After coating the polyamic acid resin solution, heat each elongated support substrate 2 to 150 to 160 ° C. In addition to removing the solvent contained in the resin solution, the polyamic acid is made in a higher temperature heat treatment Imidation. The heat treatment during the amidation is performed continuously after removing a certain degree of solvent, from a temperature of about 160 ° C to a temperature of about 350 ° C. Raise the temperature stepwise or stepwise.

After the above-mentioned heat treatment, it can be used as a laminated support body 10 in which a polyamide layer 1 is formed on a support substrate 2 having a long strip shape. Here, the polyimide layer 1 on the supporting substrate 2 is a transparent polyimide layer 1 having a transmittance of 70% or more in a wavelength region of 440 nm to 780 nm. However, in the present invention, the above heating is particularly preferred. When the temperature of the treatment is increased, the heating time (hereinafter referred to as the high-temperature maintenance time) in the high-temperature heating temperature range from a temperature lower than the highest heating temperature (highest reaching temperature) of 20 ° C. to the highest reaching temperature is within 15 minutes. When the high-temperature maintaining time exceeds 15 minutes, the transparency of the polyimide layer tends to decrease due to coloring and the like. In order to maintain transparency, the high temperature maintenance time should be short, but if the time is too short, the effect of heat treatment may not be obtained sufficiently. The most suitable high-temperature maintaining time varies depending on the heating method, the heat capacity of the support substrate 2, the thickness of the polyurethane layer 1, and the like, and is more preferably from 0.5 minutes to 5 minutes.

In the polyimide laminate 10 of the present invention, the bonding strength between the supporting substrate 2 and the polyimide layer 1 is within a range of 1 N / m to 500 N / m, and the polyimide layer can be easily separated from the supporting substrate 2 and contains polyimide. The polyimide membrane of the amidine layer 1 is not particularly limited in terms of its separation form. For example, the polyimide laminate 10 including the polyimide layer 1 on the support substrate 2 can be directly rolled into this state, or it can be used in the middle of the roll-to-roll process. After the amidation step is completed, before the winding step, the support substrate 2 and the polyimide layer 1 are peeled off and separated. Alternatively, a sheet-shaped polyurethane laminate 10 having a predetermined size can be prepared for each piece, and the polyurethane layer 1 can be peeled off from the supporting substrate 2 and separated. In any case, if polyimide The functional layer 3 is formed on the surface of the layer 1, and the separated polyurethane film can be used as a resin substrate. In particular, if the functional layer 3 is formed before the polyurethane layer 1 is separated from the supporting substrate, it can be fully used. Ensure the operability and dimensional stability of the polyurethane film.

The polyimide laminate 10 of the present invention is characterized in that the bonding strength between the support substrate 2 and the polyimide layer 1 is low, and these can be easily separated. However, in obtaining such a polyimide laminate 10 In the process, a part of the interface between the support substrate 2 and the polyurethane layer 1 with a high bonding strength (over 500 N / m) may be temporarily set, and then the part is cut off to obtain the polyurethane laminate of the present invention. 10. That is, for example, for the purpose of improving the morphological stability during long-term storage and transportation, etc., a portion of the surface of the support substrate 2 is intentionally roughened, and then a polyamic acid solution is applied to form polyimide. Layer 1 and make the bonding strength of one part of the interface higher than most other faces (more than 500N / m). After that, the part with high bonding strength can be removed by cutting. It can also be used as the polyimide of the present invention. Laminated body 10.

Hereinafter, the content of the present invention will be described in more detail based on the embodiments, but the present invention is not limited to the scope of these embodiments.

Examples

First, the abbreviations of raw material monomers and solvents used in the synthesis of polyimide are shown below, and the measurement methods and conditions for various physical properties in the examples are shown below.

[Short name]

‧DMAc: N, N-dimethylacetamide

‧PDA: 1,4-phenylenediamine

‧TFMB: 2,2’-bis (trifluoromethyl) -4,4’-diaminobiphenyl

‧DADMB: 4,4’-diamino-2,2’-dimethylbiphenyl

‧1,3-BAB: 1,3-bis (4-aminophenoxy) benzene

‧BPDA: 3,3 ’, 4,4’-biphenyltetracarboxylic dianhydride

‧6FDA: 2,2’-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride

‧PMDA: pyromite dianhydride

[Surface roughness (Ra)]

Surface observation was performed in tapping mode using an atomic force microscope (AFM) "Multi Mode 8" made by Bruker. Four visual field observations at an angle of 10 μm were performed four times, and the average of the four times was obtained. The surface roughness (Ra) indicates an arithmetic average roughness (JIS B0601-1991).

[Peelability]

Polyurethane laminates cut into a 50 mm square size were used as evaluation samples, and the polyurethane layer and the supporting substrate were peeled from one end of the polyurethane laminate. Among those that can be peeled, those that can be easily peeled without causing damage to the polyimide layer are ○, and those that see film stretching and cracking are ×. At the time of peeling, the adhesion between the polyurethane layer and the supporting substrate is strong and cannot be peeled off.

[Peel strength]

Using the Strograph R-1 manufactured by Toyo Seiki Seisakusho Co., Ltd., the polyurethane laminate was cut into a strip-shaped sample having a width of 10 mm, and the peel strength was evaluated by a T-shaped peel test method.

[Transmittance (%)]

Determination of Polyimide Film in U 4000 Spectrophotometer (50mm × 50mm) average value of light transmittance from 440nm to 780nm.

[Glass transition temperature Tg]

Using a viscoelasticity analyzer (RSA-II manufactured by Rheometric Scientific Co., Ltd.), a 10-mm-wide sample was used to give a vibration of 1 Hz. The maximum loss tangent (TaN δ) was used to determine the glass transition temperature.

[Coefficient of Thermal Expansion (CTE)]

Put a polyimide film with a size of 3mm × 15mm in a thermomechanical analysis (TMA) device, add a weight of 5.0g, and at a certain temperature increase rate (20 ° C / min) at a temperature range of 30 ° C to 260 ° C A tensile test was performed during the test, and the thermal expansion coefficient (× 10 ^-6 / K) was measured from the elongation of the polyurethane film with respect to temperature.

Synthesis Example 1 (Polyimide A)

In a 300 ml separable flask under a stream of nitrogen, 8.00 g of the PDA was dissolved in the solvent DMAc while stirring. Next, 22.00 g of BPDA was added to this solution. After that, the solution was continuously stirred at room temperature for 5 hours to carry out the polymerization reaction, and allowed to stand for a whole day. A viscous polyamino acid solution was obtained, and it was confirmed that polyamino acid A having a high degree of polymerization had been formed.

Synthesis Example 2 (Polyimide B)

Under a stream of nitrogen, in a 300 ml separable flask, while stirring, 19.11 g of DADMB and 2.92 g of 1,3-BAB were dissolved in the solvent DMAc. Next, 5.79 g of BPDA and 17.17 g of PMDA were added to this solution. After that, the solution was continuously stirred at room temperature for 5 hours to carry out the polymerization reaction, and allowed to stand for a whole day. Obtain a viscous polyamic acid solution and confirm that A high degree of polymerization of polyamic acid B.

Synthesis Example 3 (Polyimide C)

Under a stream of nitrogen, in a 300 ml separable flask, while stirring, 12.08 g of TFMB was dissolved in the solvent DMAc. Next, 6.20 g of PMDA and 4.21 g of 6FDA were added to this solution. After that, the solution was continuously stirred at room temperature for 5 hours to carry out the polymerization reaction, and allowed to stand for a whole day. A viscous polyamic acid solution was obtained, and it was confirmed that a high degree of polymerization of poly (amino acid) C was formed.

Synthesis Example 4 (Polyimide D)

Under a stream of nitrogen, in a 300 ml separable flask, while stirring, 13.30 g of TFMB was dissolved in the solvent DMAc. Next, 9.20 g of PMDA was added to this solution. After that, the solution was continuously stirred at room temperature for 5 hours to carry out the polymerization reaction, and allowed to stand for a whole day. A viscous polyamino acid solution was obtained, and it was confirmed that polyamino acid D having a high degree of polymerization had been formed.

Example 1

The resin solution of the polyamic acid A obtained in Synthesis Example 1 was applied to an electrolytic copper foil having a thickness of 18 μm, and then dried at 130 ° C. to remove the solvent. Next, the amidation was performed by a heat treatment at a temperature rising rate of about 15 ° C / min from 160 ° C to 360 ° C to obtain a polyimide layer having a thickness of 25 μm (surface roughness Ra = 1.3nm, Tg = 355 ° C).

The polyimide layer of the obtained supporting substrate was coated with the resin solution of the polyamic acid C obtained in Synthesis Example 3 at a uniform thickness, and then heated and dried at 130 ° C. to remove the solvent in the resin solution. Next, the polyimide is aminated by a heat treatment at a heating rate of about 20 ° C / min from 160 ° C to 360 ° C, and the polyimide is provided with a supporting substrate on the back side of the polyimide layer. Amine laminate. In this state, it was directly cooled to normal temperature, and a part of the polyurethane layer was torn off from the self-supporting substrate to obtain a transparent polyurethane film having a thickness of 25 μm. The peelability between the support substrate and the transparent polyurethane film when peeled off is good. In addition, in the amidation of polyamic acid C, the heating time (high-temperature maintaining time) in the high-temperature heating temperature range from a temperature lower than the highest reaching temperature of 20 ° C to the highest reaching temperature, that is, from 340 ° C to 360 The high temperature holding time at ℃ is 1 minute.

The characteristics of the supporting substrate used in each embodiment (including the case of this Example 1), the characteristics of the polyimide layer or the polyimide film formed on the supporting substrate, and the polyimide laminate The evaluation results and other series are shown in Table 1.

Example 2

A 25 μm-thick polyimide film (Kapton H, manufactured by Toray DuPont Co., Ltd .: surface roughness Ra = 70 nm, Tg = 428 ° C) was used as a support substrate, and the polymer obtained in Synthesis Example 3 was coated thereon. Resin solution of phosphonic acid C, and then dried by heating at 130 ° C to remove the solvent in the resin solution. Then, the polyimide is aminated with a heat treatment at a temperature-increasing rate of about 20 ° C / min from 160 ° C to 360 ° C (high-temperature maintenance time from 340 ° C to 360 ° C for 1 minute) as polyimide The back side of the layer is provided with a polyurethane laminate that supports the substrate. In this state, it was directly cooled to normal temperature, and a part of the polyurethane layer was torn off from the self-supporting substrate to obtain a transparent polyurethane film having a thickness of 25 μm. The peelability between the support substrate and the transparent polyurethane film when peeled off is good.

Example 3

Polyimide film (UPILEX-S, manufactured by Ube Industries, Ltd .: surface roughness Ra = 15nm, Tg = 359 ° C) with a thickness of 25 μm was used as a supporting substrate, and the obtained in Synthesis Example 4 was applied thereon The resin solution of the polyamic acid D is then heated and dried at 130 ° C to remove the solvent in the resin solution. Then, the polyimide is aminated with a heat treatment at a temperature-increasing rate of about 20 ° C / min from 160 ° C to 360 ° C (high-temperature maintenance time from 340 ° C to 360 ° C for 1 minute) as polyimide The back side of the layer is provided with a polyurethane laminate that supports the substrate. In this state, it was directly cooled to normal temperature, and a part of the polyurethane layer was torn off from the self-supporting substrate to obtain a transparent polyurethane film having a thickness of 25 μm. The peelability between the support substrate and the transparent polyurethane film when peeled off is good.

Example 4

Polyimide film (UPILEX-S, manufactured by Ube, 25 μm thick) Co., Ltd .: surface roughness Ra = 15nm, Tg = 359 ° C) as a supporting substrate, and a resin solution of polyamic acid D obtained in Synthesis Example 4 was coated thereon, and then heated and dried at 130 ° C. Remove the solvent from the resin solution. Next, after heating at 150 ° C, 200 ° C, and 250 ° C for 30 minutes, heating was performed at 350 ° C for 1 hour to aminate the polyimide to form a polyimide having a supporting substrate on the back side of the polyimide layer Amine laminate. In this state, it was directly cooled to normal temperature, and a part of the polyurethane layer was torn off from the self-supporting substrate to obtain a transparent polyurethane film having a thickness of 25 μm. The peelability between the support substrate and the transparent polyurethane film when peeled off is good.

Comparative Example 1

A heat treatment for coating, heating and drying, and amidation was carried out in the same manner as in Example 1 except that a copper foil was used as a supporting substrate to obtain a polyimide laminate. Although the polyimide layer is to be torn off from the polyimide laminate, the interface between the polyimide layer and the supporting substrate is strong, and the polyimide cannot be peeled from the supporting substrate.

Comparative Example 2

The copper foil of the supporting substrate used in Example 1 was etched to obtain a supporting substrate including a polyurethane film. The surface roughness Ra of the copper foil etched surface of this supporting substrate was 180 nm and Tg was 355 ° C. A polyimide laminate was obtained in the same manner as in Example 1 except that the resin solution of the polyimide C obtained in Synthesis Example 3 was applied to this side of the polyimide film of the support substrate. Although the polyimide layer is to be torn off from the polyimide laminate, the interface between the polyimide layer and the supporting substrate is strong, and the polyimide cannot be peeled from the supporting substrate.

Comparative Example 3

A polyimide substrate (UPIMOL, manufactured by Ube Industries, Ltd .: surface roughness Ra = 160 nm, Tg = 401 ° C) was used as a supporting substrate except that a thickness of 10 mm was used to obtain a polyimide. After the amidine laminate is cooled to normal temperature, the polyamide layer is torn off from the self-supporting substrate to obtain a transparent polyurethane film having a thickness of 25 μm. When the supporting substrate and the transparent polyurethane film are peeled off, the transparent polyurethane film is prone to elongation or even cracking, and the peelability is not good.

Comparative Example 4

A polyimide laminate was obtained in the same manner as in Example 3, except that the resin solution of polyamic acid B obtained in Synthesis Example 2 was used as the polyamic acid. After cooling to normal temperature, the self-supporting substrate was torn off. The polyimide layer was lowered to obtain a transparent polyimide film having a thickness of 25 μm. When the support substrate and the polyurethane film are peeled off, the polyurethane film is prone to elongation or even cracking, and the peelability is not good.

Comparative Example 5

A polyimide laminate was obtained in the same manner as in Comparative Example 4 except that a polyimide film (Kapton H, manufactured by Toray DuPont Co., Ltd.) was used as a supporting substrate. Although the polyimide layer is to be torn off from the polyimide laminate, the interface between the polyimide layer and the supporting substrate is strong, and the polyimide cannot be peeled from the supporting substrate.

Claims (5)

A polyimide laminate is a polyimide layer with a supporting substrate on the back side, characterized in that the thickness of the polyimide layer is 3 μm or more and 50 μm or less, and the polyimide layer is between 440 nm and 780 nm. The transmittance in the wavelength region is 70% or more. The surface of the support substrate at the interface between the polyimide layer and the support substrate is formed of heat-resistant polyimide having a glass transition temperature Tg of 300 ° C or higher, and the surface is rough. The degree Ra is 100 nm or less, and the bonding strength between the supporting substrate and the polyimide layer is 1N / m or more and 500N / m or less. The polyimide film including the polyimide layer can be separated from the self-supporting base material. The polyimide in the structural unit has: selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2 , 3,3 ', 4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride anhydride, and a diamine selected from p-phenylenediamine, 4,4'-diaminodiphenyl ether . The polyimide laminate according to item 1 of the scope of the patent application, wherein the heat-resistant polyimide of the supporting substrate is a polyimide having the following structural unit, A method for producing a polyimide laminate, which is a method for producing a polyimide laminate having a supporting substrate on the back side of the polyimide layer, which is characterized by having a glass transition temperature Tg of 300 ° C or higher and The strip-shaped support substrate of heat-resistant polyimide surface formed by the heat-resistant polyimide with a surface roughness Ra of 100 nm or less is heat-resistant to the strip-shaped support substrate while being transported in a roll-to-roll process. A polyamic acid resin solution is coated on the polyimide surface, and each support substrate is heat-treated at a temperature of 200 ° C or higher to aminate the polyimide, except that a 440nm to 440nm is formed on the support substrate. Polyurethane layer having a transmittance of 70% or more in a wavelength range of 780 nm, and the bonding strength between the supporting substrate and the polyurethane layer can be 1N / m or more and 500N / m or less, and the self-supporting substrate can be separated. Polyimide film including a polyimide layer; the aforementioned heat-resistant polyimide has in the structural unit: a member selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, and 2,2' , 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride anhydrides, and selected from - phenylenediamine, 4,4'-diphenyl ether group of a diamine. The method for producing a polyimide laminate as described in item 3 of the scope of the patent application, wherein the heat treatment conditions of the polyamic acid are from a temperature lower than the maximum reachable temperature of 20 ° C. to the maximum reachable temperature during heating and heating. The heating time in the high-temperature heating temperature range up to 15 minutes. The method for producing a polyimide laminate as described in item 4 of the scope of the patent application, wherein the heat-resistant polyimide of the supporting substrate is polyimide having the following structural units,