Laminate

Abstract

A laminate in which a polyimide film is adhered on a glass substrate, wherein the surface of the glass substrate that contacts the polyimide film has a surface free energy of not more than 65 mJ / m2, and the polyimide film has a proportional limit of 10-45 MPa.

Description

[Technical Field]

[0001] The present invention relates to a laminate, and more particularly to a laminate in which a polyimide film is adhered to a glass substrate. [Background technology]

[0002] Various applications of polyimide resins are being considered in the fields of electrical and electronic components, etc. For example, it is desirable to replace the glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates in order to make the devices lighter and more flexible, and research is underway into polyimide films suitable for such plastic substrates.

[0003] When using a polyimide film as a substrate, the desired electronic circuit is created on the polyimide film through various processes, such as sputtering and etching, to create an oxide semiconductor film, such as an indium tin oxide (ITO) film, depending on the application. When creating the desired electronic circuit on the polyimide film, the polyimide film is adhered to a hard support, such as a glass plate, to ensure the flatness of the polyimide film. If the polyimide film is not adhered to the support, problems will occur in the process. Furthermore, after these processes, a step is required to peel the polyimide film from the support. This peeling step is performed after the molded body on the substrate has cooled to room temperature to approximately 50°C.

[0004] Known methods for adhering a polyimide film to a support include adding an adhesive to the polyimide itself, and interposing a layer called a release layer between the polyimide film and the support to ensure adhesion during the process. The release layer is used to improve the adhesion between the glass plate and the release layer during the process, to make the adhesion between the polyimide film and the release layer adjustable, and to facilitate peeling from the polyimide film in the final step. Examples of release layers include a resin thin film-forming composition containing a heat-resistant polymer.

[0005] As a method for peeling off a polyimide film from a support, for example, the following method is known. (1) A method in which a structure containing a polyimide resin / support is obtained, and then a laser is irradiated from the support side to ablate the polyimide resin interface, thereby peeling off the polyimide resin (see, for example, Patent Document 1). Types of lasers include solid-state (YAG) lasers and gas (UV excimer) lasers, and spectra such as 308 nm are used. (2) A method in which a release layer is formed on the support before applying a resin composition to the support, and then a structure including a polyimide resin film, a release layer, and a support is obtained, and the polyimide resin film is mechanically peeled off (see, for example, Patent Document 2). Examples of release layers include methods using Parylene (registered trademark, manufactured by Japan Parylene LLC) or tungsten oxide, and methods using vegetable oil-based, silicone-based, fluorine-based, or alkyd-based release agents. Laser irradiation as described in (1) above may also be used in combination.

[0006] Furthermore, Patent Document 3 discloses a method for fixing a resin substrate to a support substrate via an adhesive layer, forming electronic elements on the resin substrate, and peeling an electronic device including the electronic elements and the resin substrate from the support substrate, in which an adhesive layer containing a material whose adhesive strength to the support substrate decreases upon contact with moisture is used as a main component. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2007-512568 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-067957 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-021384 Summary of the Invention [Problem to be solved by the invention]

[0008] When a release layer is interposed between the polyimide film and the support to ensure adhesion, the release layer remains on the polyimide film after peeling, resulting in a lack of flatness on the peeled surface. Therefore, a method that does not use a release layer has been desired. Furthermore, the method (1) above has the problem that the resin substrate formed on the base may be damaged during laser irradiation, and also requires the introduction of an expensive laser irradiation device, which poses a cost issue. Although the method (2) does not require a laser irradiation device, the release layer may not fully function depending on the type of polyimide. In the method of Patent Document 3, when forming an electronic element, it was necessary to form a sealing layer to seal the exposed areas of the adhesive layer in order to prevent the adhesive layer from coming into contact with moisture so as not to reduce the adhesive strength. Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminate that does not have the above-mentioned problems and that allows a polyimide film to be stably peeled from a glass substrate without using a release layer. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have found that the above-mentioned problems can be solved by a polyimide-glass laminate in which the surface free energy of the glass substrate surface and the proportional limit of the polyimide film are each set to specific values. The present invention was completed based on this finding.

[0010] That is, the present invention relates to the following. <1> A laminate in which a polyimide film is adhered to a glass substrate, wherein the surface free energy of the contact surface between the glass substrate and the polyimide film is 65 mJ / m 2 or less, and the proportional limit of the polyimide film is 10 to 45 MPa. <2> The polyimide film has a peel strength from a glass substrate of 20 gf / cm or less. <1> The laminate according to claim 1. <3> The polyimide film has a thickness of 3 to 20 μm. <1> or <2> The laminate according to claim 1. <4> the polyimide resin of the polyimide film has a structural unit A1 derived from a tetracarboxylic dianhydride and a structural unit B1 derived from a diamine, the structural unit A1 containing a structural unit (A11) derived from a compound represented by the following formula (a11), and the structural unit B1 containing a structural unit (B11) derived from a compound represented by the following formula (b11): <1> ~ <3> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the [ka] <5> The structural unit A1 further contains a structural unit (A12) derived from a compound represented by the following formula (a12): <4> The laminate according to claim 1. [ka] <6> At least one film selected from the group consisting of a metal film, a semiconductor film, and an insulating film is further laminated on the polyimide film. <1> ~ <5> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the <7> The semiconductor film is at least one selected from the group consisting of indium tin oxide, amorphous silicon, indium gallium zinc oxide, and low-temperature polysilicon. <6> The laminate according to claim 1. <8> A method for producing a laminate, comprising applying at least one varnish selected from the group consisting of polyimide varnish, polyamic acid varnish, and varnish obtained by dissolving a copolymer having imide repeating structural units and amidic acid repeating structural units in an organic solvent onto a glass substrate and drying the applied varnish to form a polyimide film, the method comprising at least one step selected from a glass substrate alkali cleaning step and a glass substrate ozone treatment step prior to applying the varnish, and a step of adjusting the proportional limit of the resulting polyimide film to be 10 to 45 MPa. <9> The step of adjusting the proportional limit of the obtained polyimide film to be 10 to 45 MPa is the step of adding a resin additive to the varnish, and the method for producing the laminate according to <8> above. <10> The method for producing the laminate according to <9> above, wherein the resin additive is at least one selected from the group consisting of a phosphate ester compound, an amino-modified silicone oil, and a silicone-containing polymer. <11> A conductive film obtained by peeling and removing the glass substrate from the laminate according to <6> or <7> above.

Advantages of the Invention

[0011] Even when the polyimide film is mechanically peeled from the glass substrate without using a release layer, the laminate of the present invention can be peeled easily and stably. Therefore, the laminate of the present invention can contribute to simplifying the manufacturing process of flexible electronic devices provided with resin substrates and improving the yield thereof.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described. The content of the present invention is not limited to the embodiments described below. In this specification, the term "A to B" regarding the description of numerical values means "A or more and B or less" (when A < B) or "A or less and B or more" (when A > B). In the present invention, a combination of preferred embodiments is a more preferred embodiment.

[0013] [Laminate] The laminate of the present invention is a laminate in which a polyimide film is adhered to a glass substrate, and the surface free energy of the contact surface of the glass substrate with the polyimide film is 65 mJ / m 2 or less, and the proportional limit of the polyimide film is 10 to 45 MPa.

[0014] <Glass Substrate> The glass substrate used in the laminate of the present invention has a surface free energy of 65 mJ / m 2 There are no particular limitations as long as the strength is sufficient to support the polyimide film when producing an electronic device (conductive film) using the polyimide film as a substrate. The surface free energy of the contact surface between the glass substrate and the polyimide film is 65 mJ / m 2 less than 60 mJ / m 2 or less, more preferably 58 mJ / m 2 or less, and more preferably 57 mJ / m 2 Preferably, the value is 30 mJ / m or less. 2 That's all. The type of glass is not particularly limited, and alkali-free glass (borosilicate glass), alkali glass, soda glass, non-fluorescent glass, phosphate glass, borate glass, quartz, etc. can be used. To improve adhesion to the polyimide film, the upper surface of the glass substrate preferably has high flatness. Specifically, the surface roughness Rmax is preferably 10 μm or less, and more preferably 1 μm or less.

[0015] <Polyimide film> In the laminate of the present invention, a polyimide film is adhered to a glass substrate. The polyimide film is preferably directly adhered to the glass substrate, and it is preferable that no adhesive layer or the like is interposed between the glass substrate and the polyimide film.

[0016] The proportional limit of the polyimide film used in the laminate of the present invention is 10 to 45 MPa, preferably 20 to 45 MPa, more preferably 25 to 45 MPa, and even more preferably 25 to 40 MPa. It is believed that when the proportional limit is 10 MPa or more, the strength required for peeling and use is provided, and when the proportional limit is 45 MPa or less, the flexibility required for deformation during peeling is provided. Here, the proportional limit is as follows: In a tensile test of a polyimide film, stress changes linearly with strain in the initial stage of the test. In other words, stress is proportional to strain. The maximum stress within this proportional range is called the proportional limit. The proportional limit can be measured by a tensile test in accordance with JIS K7127:1999, and specifically, it can be determined by the method described in the examples. When the proportional limit of the polyimide film is within the above range, the film can be stably peeled from the glass substrate without using a release layer. Although the reason for this is unclear, it is thought that because the film is peeled off through bending deformation, a suitably small proportional limit makes the film easy to bend and peel off.

[0017] The thickness of the polyimide film is preferably 3 to 20 μm, more preferably 4 to 15 μm, and even more preferably 5 to 10 μm. When the thickness of the polyimide film is within this range, the polyimide film is not damaged during the production of the electronic device, the production of the electronic device is easy, and after the electronic device is produced, the polyimide film can be stably peeled off from the glass substrate. The thickness of the polyimide film can be measured physically using a micrometer or the like, or can be determined by optical observation using a laser microscope or the like and measuring the height between the top surface of the film and the surface that contacts the glass.

[0018] The peel strength of the polyimide film from a glass substrate is preferably 20 gf / cm or less, more preferably 15 gf / cm or less, even more preferably 10 gf / cm or less, still more preferably 9 gf / cm or less, and even more preferably 7 gf / cm or less. When the peel strength is within this range, the polyimide film adheres to the glass substrate during the production of the electronic device and does not peel off, and can be stably peeled from the glass substrate after the production of the electronic device.

[0019] The polyimide film used in the laminate of the present invention may be composed of only a polyimide resin, or may contain various additives, such as resin additives and the various additives described in the sections describing each varnish below. It is preferable that the polyimide film contains a resin additive. Preferred resin additives include phosphate ester compounds, amino-modified silicone oils, silicone-containing polymers, acrylic polymers, and fluorine-containing polymers, and more preferably at least one selected from the group consisting of phosphate ester compounds, amino-modified silicone oils, and silicone-containing polymers. From the viewpoint of reducing the peel strength of the laminate, it is preferable to use two or more resin additives in combination, it is more preferable to use a phosphate ester compound and a silicone-containing polymer in combination, and it is even more preferable to use a phosphate ester compound, amino-modified silicone oil, and a silicone-containing polymer in combination. As the phosphate ester compound, acidic phosphate ester compounds are preferred, and dibutyl phosphate is more preferred. By including the additive, it is possible to reduce the proportional limit, and the proportional limit can be set within the above range. The content of the additive is preferably 0.01 to 0.7% by mass, more preferably 0.05 to 0.5% by mass, and even more preferably 0.05 to 0.2% by mass, based on the polyimide resin constituting the polyimide film. In particular, when a phosphate ester compound is used, the content is preferably 0.01 to 0.7 mass %, more preferably 0.01 to 0.3 mass %, and even more preferably 0.01 to 0.1 mass %, relative to the polyimide resin constituting the polyimide film. When amino-modified silicone oil is used, the amount is preferably 0.3 to 0.7 mass %, more preferably 0.3 to 0.6 mass %, and even more preferably 0.3 to 0.5 mass %, relative to the polyimide resin constituting the polyimide film. Furthermore, when a silicone-containing polymer is used, its content is preferably 0.05 to 0.7 mass %, more preferably 0.05 to 0.3 mass %, and even more preferably 0.05 to 0.1 mass %, relative to the polyimide resin constituting the polyimide film. When the polyimide film contains a resin additive, the content of the polyimide resin constituting the polyimide film is preferably 99.3 to 99.99 mass %, more preferably 99.5 to 99.95 mass %, and even more preferably 99.8 to 99.95 mass % in the polyimide film.

[0020] Next, preferred examples of polyimide resins that can be used in the polyimide film used in the laminate of the present invention will be shown, but the present invention is not limited to these. Of the polyimide resins 1 and 2 listed below, polyimide resin 1 is preferred from the viewpoint of ease of peeling. Polyimide resin 2 is preferably obtained by imidizing copolymer 2 having an imide repeating structural unit and an amic acid repeating structural unit.

[0021] [Polyimide resin 1] Polyimide resin 1 has a structural unit A1 derived from a tetracarboxylic dianhydride and a structural unit B1 derived from a diamine, where structural unit A1 contains a structural unit (A11) derived from a compound represented by formula (a11) below, and structural unit B1 contains a structural unit (B11) derived from a compound represented by formula (b11) below.

[0022] [ka]

[0023] <Constituent unit A1> The structural unit A1 is a structural unit derived from a tetracarboxylic dianhydride contained in the polyimide resin 1, and includes a structural unit (A11) derived from a compound represented by the following formula (a11).

[0024] [ka]

[0025] The compound represented by formula (a11) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride. The structural unit (A11) can improve colorless transparency and optical isotropy. The proportion of the structural unit (A11) in the structural unit A1 is preferably 5 mol% or more, more preferably 20 mol% or more, even more preferably 50 mol% or more, even more preferably 70 mol% or more, and even more preferably 90 mol% or more. There is no particular upper limit for the proportion of the structural unit (A11), and it is 100 mol% or less. The structural unit A1 may be composed solely of the structural unit (A11).

[0026] It is preferable that the structural unit A1 further contains a structural unit (A12) derived from a compound represented by the following formula (a12).

[0027] [ka]

[0028] The compound represented by formula (a12) is 4,4'-oxydiphthalic anhydride. When the structural unit A1 contains both the structural unit (A11) and the structural unit (A12), the colorless transparency, optical isotropy, and chemical resistance of the film can be improved. The structural unit (A12) in particular makes a significant contribution to improving chemical resistance.

[0029] When the structural unit A1 contains both the structural unit (A11) and the structural unit (A12), the proportion of the structural unit (A11) within the structural unit A1 is preferably 5 to 95 mol %, more preferably 15 to 95 mol %, even more preferably 20 to 90 mol %, still more preferably 50 to 90 mol %, and particularly preferably 70 to 90 mol %. The proportion of the structural unit (A12) within the structural unit A1 is preferably 5 to 95 mol %, more preferably 5 to 85 mol %, even more preferably 10 to 80 mol %, still more preferably 10 to 50 mol %, and especially preferably 10 to 30 mol %. The total proportion of the structural units (A11) and (A12) in the structural unit A1 is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. There is no particular upper limit for the total proportion of the structural units (A11) and (A12), but it is 100 mol% or less. The structural unit A1 may be composed only of the structural unit (A11) and the structural unit (A12).

[0030] The structural unit A1 may contain structural units other than the structural units (A11) and (A12). Tetracarboxylic acid dianhydrides that provide such structural units are not particularly limited, but include aromatic tetracarboxylic acid dianhydrides such as pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride; alicyclic tetracarboxylic acid dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid dianhydride; and aliphatic tetracarboxylic acid dianhydrides such as 1,2,3,4-butanetetracarboxylic acid dianhydride. In this specification, aromatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing one or more alicyclic rings but no aromatic rings, and aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing neither an aromatic ring nor an alicyclic ring. The structural units optionally contained in the structural unit A1 (that is, structural units other than the structural units (A11) and (A12)) may be of one type, or may be of two or more types.

[0031] <Structural unit B1> The structural unit B1 is a structural unit derived from a diamine contained in the polyimide resin, and includes a structural unit (B11) derived from a compound represented by the following formula (b11). [ka]

[0032] The compound represented by formula (b11) is 3,3'-diaminodiphenyl sulfone. When the structural unit B1 includes the structural unit (B11), the optical isotropy and chemical resistance of the film can be improved. The proportion of the structural unit (B11) in the structural unit B1 is preferably 5 mol% or more, more preferably 20 mol% or more, even more preferably 50 mol% or more, still more preferably 70 mol% or more, and even more preferably 80 mol% or more. There are no particular upper limits for the proportion of the structural unit (B11), and it is 100 mol% or less. The structural unit B1 may consist solely of the structural unit (B11).

[0033] It is preferable that the structural unit B1 further includes a structural unit (B12). The structural unit (B12) is preferably at least one selected from the group consisting of a structural unit (B121) derived from a compound represented by the following formula (b121), a structural unit (B122) derived from a compound represented by the following formula (b122), a structural unit (B123) derived from a compound represented by the following formula (b123), a structural unit (B124) derived from a compound represented by the following formula (b124), and a structural unit (B125) derived from a compound represented by the following formula (b125). Among these, at least one selected from the structural unit (B121) derived from a compound represented by the following formula (b121) and the structural unit (B122) derived from a compound represented by the following formula (b122) is more preferred, and the structural unit (B121) derived from a compound represented by the following formula (b121) is even more preferred.

[0034] [ka] (In formula (b124), each R independently represents a hydrogen atom, a fluorine atom, or a methyl group.)

[0035] The compound represented by formula (b121) is 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane. When the structural unit B1 includes the structural unit (B121), the colorless transparency of the film can be improved.

[0036] The compound represented by formula (b122) is bis[4-(4-aminophenoxy)phenyl]sulfone. When the structural unit B1 includes the structural unit (B122), the tensile elongation of the film can be improved. The compound represented by formula (b123) is 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA). When the structural unit B1 includes the structural unit (B123), the colorless transparency of the film can be improved.

[0037] In formula (b124), each R is independently selected from the group consisting of a hydrogen atom, a fluorine atom, and an alkyl group having 1 to 5 carbon atoms, and is preferably a hydrogen atom, a fluorine atom, or a methyl group. Examples of compounds represented by formula (b124) include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9,9-bis(3-methyl-4-aminophenyl)fluorene, and at least one selected from the group consisting of these three compounds is preferred, with 9,9-bis(4-aminophenyl)fluorene being preferred. When the structural unit B1 includes the structural unit (B124), the optical isotropy and heat resistance of the film can be improved.

[0038] The compound represented by formula (b125) is 2,2'-bis(trifluoromethyl)benzidine. When the structural unit B1 includes the structural unit (B125), the colorless transparency, chemical resistance, and mechanical properties of the film can be improved.

[0039] The structural unit (B12) may be only the structural unit (B121), only the structural unit (B122), only the structural unit (B123), only the structural unit (B124), or only the structural unit (B125). Furthermore, the structural unit (B12) may be a combination of two or more structural units selected from the group consisting of structural units (B121) to (B125).

[0040] When the structural unit B1 contains both the structural unit (B11) and the structural unit (B12), the proportion of the structural unit (B11) in the structural unit B1 is preferably 5 to 95 mol %, more preferably 15 to 95 mol %, even more preferably 20 to 90 mol %, still more preferably 50 to 90 mol %, and particularly preferably 70 to 90 mol %. The proportion of the structural unit (B12) within the structural unit B1 is preferably 5 to 95 mol %, more preferably 5 to 85 mol %, even more preferably 10 to 80 mol %, still more preferably 10 to 50 mol %, and especially preferably 10 to 30 mol %. The total proportion of the structural units (B11) and (B12) in the structural unit B1 is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. There is no particular upper limit for the total proportion of the structural units (B11) and (B12), but it is 100 mol% or less. The structural unit B1 may be composed only of the structural unit (B11) and the structural unit (B12).

[0041] The structural unit B1 may contain structural units other than the structural units (B11) and (B12). Diamines that provide such structural units include, but are not limited to, 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, α,α'-bis(4-aminophenyl) ... aromatic diamines such as 4,4'-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether (excluding the compound represented by formula (b-11)); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine. In this specification, aromatic diamine means a diamine containing one or more aromatic rings, alicyclic diamine means a diamine containing one or more alicyclic rings but no aromatic rings, and aliphatic diamine means a diamine containing neither an aromatic ring nor an alicyclic ring. The structural units optionally contained in the structural unit B1 (that is, structural units other than the structural units (B11) and (B12)) may be of one type, or may be of two or more types.

[0042] From the viewpoint of the mechanical strength of the resulting polyimide film, the number average molecular weight of the polyimide resin 1 is preferably 5,000 to 200,000. The number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) equivalent value measured by gel permeation chromatography.

[0043] The polyimide resin 1 may contain a structure other than a polyimide chain (a structure formed by imide bonding between the structural unit A1 and the structural unit B1). Examples of structures other than polyimide chains that can be contained in the polyimide resin include structures containing amide bonds. The polyimide resin 1 preferably contains a polyimide chain (a structure formed by imide bonding between the structural unit A1 and the structural unit B1) as the main structure. Therefore, the proportion of the polyimide chain in the polyimide resin 1 is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 99% by mass or more, but 100% by mass or less.

[0044] [Method of manufacturing polyimide resin 1] Polyimide resin 1 can be produced by reacting a tetracarboxylic acid component containing a compound that provides the above-mentioned structural unit (A11) with a diamine component that contains a compound that provides the above-mentioned structural unit (B11). The tetracarboxylic acid component may contain a compound that provides the structural unit (A12) described above, and the diamine component preferably contains a compound that provides the structural unit (B12) described above.

[0045] Compounds that provide the structural unit (A11) include, but are not limited to, compounds represented by formula (a11), and may also be derivatives thereof as long as they provide the same structural unit. Such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by formula (a11) (i.e., 1,2,4,5-cyclohexanetetracarboxylic acid) and alkyl esters of such tetracarboxylic acids. Compounds that provide the structural unit (A11) are preferably compounds represented by formula (a11) (i.e., dianhydrides). Similarly, examples of compounds that provide the structural unit (A12) include, but are not limited to, compounds represented by formula (a12), and derivatives thereof may also be used as long as they provide the same structural unit. Examples of such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic acid dianhydrides represented by formula (a12) and alkyl esters of such tetracarboxylic acids. Compounds represented by formula (a12) (i.e., dianhydrides) are preferred as compounds that provide the structural unit (A12).

[0046] The tetracarboxylic acid component preferably contains at least 5 mol%, more preferably at least 20 mol%, even more preferably at least 50 mol%, even more preferably at least 70 mol%, and still more preferably at least 90 mol% of the compound that provides the structural unit (A11). There are no particular upper limits for the proportion of the compound that provides the structural unit (A11), and the upper limit is up to 100 mol%. When the tetracarboxylic acid component contains both a compound that provides structural unit (A11) and a compound that provides structural unit (A12), it preferably contains 5 to 95 mol%, more preferably 15 to 95 mol%, even more preferably 20 to 90 mol%, still more preferably 50 to 90 mol%, and especially preferably 70 to 90 mol% of the compound that provides structural unit (A11).It also preferably contains 5 to 95 mol%, more preferably 5 to 85 mol%, even more preferably 10 to 80 mol%, still more preferably 10 to 50 mol%, and especially preferably 10 to 30 mol% of the compound that provides structural unit (A12). The tetracarboxylic acid component preferably contains at least 50 mol%, more preferably at least 70 mol%, even more preferably at least 90 mol%, and particularly preferably at least 99 mol%, of the compound that provides the structural unit (A11) and the compound that provides the structural unit (A12). There are no particular upper limits for the total content of the compound that provides the structural unit (A-11) and the compound that provides the structural unit (A12), but it is 100 mol% or less. The tetracarboxylic acid component may consist solely of the compound that provides the structural unit (A11) and the compound that provides the structural unit (A12).

[0047] The tetracarboxylic acid component may contain compounds other than the compounds that provide the structural unit (A11) and the compounds that provide the structural unit (A12). Examples of such compounds include the above-mentioned aromatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides, as well as derivatives thereof (tetracarboxylic acids, alkyl esters of tetracarboxylic acids, etc.). The compound optionally contained in the tetracarboxylic acid component (that is, a compound other than the compound that provides the structural unit (A11) and the compound that provides the structural unit (A12)) may be one type, or two or more types.

[0048] Compounds that provide the structural unit (B11) include, but are not limited to, compounds represented by formula (b11), and may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamines represented by formula (b11). Compounds that provide the structural unit (B11) are preferably compounds represented by formula (b11) (i.e., diamines). Compounds that provide the structural unit (B12) include, but are not limited to, compounds represented by formula (b121), (b122), (b123), (b124), and (b125), and may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to these diamines. Diamines are preferred as compounds that provide the structural unit (B12).

[0049] The diamine component preferably contains at least 5 mol%, more preferably at least 20 mol%, even more preferably at least 50 mol%, even more preferably at least 70 mol%, and even more preferably at least 80 mol% of the compound that provides the structural unit (B11). There are no particular upper limits for the proportion of the compound that provides the structural unit (B11), and the upper limit is up to 100 mol%. When the diamine component contains both a compound that provides the structural unit (B11) and a compound that provides the structural unit (B12), it preferably contains 5 to 95 mol%, more preferably 15 to 95 mol%, even more preferably 20 to 90 mol%, still more preferably 50 to 90 mol%, and especially preferably 70 to 90 mol% of the compound that provides the structural unit (B11), and it also preferably contains 5 to 95 mol%, more preferably 5 to 85 mol%, even more preferably 10 to 80 mol%, still more preferably 10 to 50 mol%, and especially preferably 10 to 30 mol% of the compound that provides the structural unit (B12). The diamine component preferably contains at least 50 mol%, more preferably at least 70 mol%, even more preferably at least 90 mol%, and particularly preferably at least 99 mol% of the compound that provides the structural unit (B11) and the compound that provides the structural unit (B12). There are no particular upper limits for the total proportion of the compound that provides the structural unit (B11) and the compound that provides the structural unit (B12), and the upper limit is up to 100 mol%. The diamine component may consist solely of the compound that provides the structural unit (B11) and the compound that provides the structural unit (B12).

[0050] The diamine component may contain compounds other than the compound that provides the structural unit (B11) and the compound that provides the structural unit (B12). Examples of such compounds include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, as well as derivatives thereof (diisocyanates, etc.). The compound optionally contained in the diamine component (that is, a compound other than the compound that provides the structural unit (B11) and the compound that provides the structural unit (B12)) may be one type, or two or more types.

[0051] The ratio of the amount of the tetracarboxylic acid component to the amount of the diamine component used in producing the polyimide resin 1 is preferably 0.9 to 1.1 moles of the diamine component per mole of the tetracarboxylic acid component.

[0052] In addition to the tetracarboxylic acid component and diamine component, a terminal blocking agent may be used in the production of polyimide resin 1. Monoamines or dicarboxylic acids are preferred as terminal blocking agents. The amount of terminal blocking agent to be introduced is preferably 0.0001 to 0.1 mol, particularly 0.001 to 0.06 mol, per mol of the tetracarboxylic acid component. Examples of monoamine terminal blocking agents that are recommended include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, and 4-methylaniline. Of these, benzylamine and aniline are preferred. Dicarboxylic acids are preferred as dicarboxylic acid terminal blocking agents, and some of these may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. are recommended. Of these, phthalic acid and phthalic anhydride are preferably used.

[0053] There are no particular limitations on the method for reacting the tetracarboxylic acid component and the diamine component, and any known method can be used. Specific reaction methods include: (1) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, and the mixture is stirred at 10 to 110°C for 0.5 to 30 hours, and then the temperature is raised to carry out the imidization reaction; (2) a method in which a diamine component and a reaction solvent are charged into a reactor and dissolved, and then the tetracarboxylic acid component is charged, and the mixture is stirred at 10 to 110°C for 0.5 to 30 hours as needed, and then the temperature is raised to carry out the imidization reaction; and (3) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, and the temperature is immediately raised to carry out the imidization reaction.

[0054] The reaction solvent used in the production of the polyimide resin 1 may be any solvent that does not inhibit the imidization reaction and can dissolve the resulting polyimide resin, such as aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

[0055] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone; amine solvents such as picoline and pyridine; and ester solvents such as 2-methoxy-1-methylethyl acetate.

[0056] Specific examples of phenol-based solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Specific examples of ether solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, and 1,4-dioxane. Specific examples of carbonate solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Among the above reaction solvents, amide-based solvents and lactone-based solvents are preferred. The above reaction solvents may be used alone or in combination of two or more.

[0057] The imidization reaction is preferably carried out while removing water generated during the production using a Dean-Stark apparatus, etc. By performing such an operation, the degree of polymerization and the imidization rate can be further increased.

[0058] In the imidization reaction, a known imidization catalyst can be used, such as a base catalyst or an acid catalyst. Examples of the base catalyst include organic base catalysts such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, and N,N-diethylaniline; and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate, and sodium hydrogencarbonate. Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid, naphthalenesulfonic acid, etc. The above imidization catalysts may be used alone or in combination of two or more. Among the above, from the viewpoint of ease of handling, it is preferable to use a base catalyst, it is more preferable to use an organic base catalyst, it is even more preferable to use triethylamine, and it is particularly preferable to use a combination of triethylamine and triethylenediamine.

[0059] The temperature of the imidization reaction is preferably 120 to 250° C., more preferably 160 to 200° C., from the viewpoint of the reaction rate and suppression of gelation, etc. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

[0060] The solid content concentration during the imidization reaction is preferably 30 to 60 mass%, more preferably 35 to 58 mass%, and particularly preferably 40 to 56 mass%. When the solid content concentration during the imidization reaction is within this range, the imidization reaction proceeds smoothly and water generated during the reaction is easily removed, thereby increasing the degree of polymerization and the imidization rate. The solid content concentration during the imidization reaction is a value calculated from the following formula based on the masses of the tetracarboxylic acid component added to the reaction system, the diamine component in the reaction system, and the reaction solvent. Solid content concentration during imidization reaction (mass%)=(total mass of tetracarboxylic acid component and diamine component) / (total mass of tetracarboxylic acid component, diamine component, and reaction solvent)×100

[0061] [Polyimide resin 2 and copolymer 2] Polyimide resin 2 is a polyimide resin obtained by imidizing copolymer 2 having an imide repeating structural unit and an amic acid repeating structural unit. Copolymer 2 will be described below, but polyimide resin 2 obtained by imidizing copolymer 2 is used for the polyimide film used in the laminate of the present invention.

[0062] Copolymer 2 is a precursor of polyimide resin 2, and comprises an imide repeating structural unit having a structural unit A2i derived from a tetracarboxylic dianhydride and a structural unit B2i derived from a diamine, an amic acid repeating structural unit having a structural unit A2a derived from a tetracarboxylic dianhydride and a structural unit B2a derived from a diamine, the structural unit A2, which includes the structural units A2i and A2a, includes a structural unit (A21) derived from a tetracarboxylic dianhydride (a21); the structural unit B2, which includes the structural units B2i and B2a, includes a structural unit (B21) derived from a compound represented by the following formula (b21): The structural unit (A21) is preferably a copolymer containing at least one selected from the group consisting of a structural unit (A211) derived from a compound represented by the following formula (a211), a structural unit (A212) derived from a compound represented by the following formula (a212), a structural unit (A213) derived from a compound represented by the following formula (a213), and a structural unit (A214) derived from a compound represented by the following formula (a214).

[0063] [ka]

[0064] <Constituent unit A2> Structural unit A2 is a structural unit derived from a tetracarboxylic dianhydride contained in copolymer 2, and includes a structural unit (A21) derived from a tetracarboxylic dianhydride (a21). From the standpoint of high heat resistance and low residual stress, the structural unit (A21) includes at least one selected from the group consisting of a structural unit (A211) derived from a compound represented by the following formula (a211), a structural unit (A212) derived from a compound represented by the following formula (a212), a structural unit (A213) derived from a compound represented by the following formula (a213), and a structural unit (A214) derived from a compound represented by the following formula (a214). The structural unit (A21) is included in the structural unit A2i derived from the tetracarboxylic dianhydride contained in the imide repeating structural unit, but it is preferable that the structural unit A2a derived from the tetracarboxylic dianhydride contained in the amic acid repeating structural unit also contains the structural unit (A21).

[0065] [ka]

[0066] The compound represented by formula (a211) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by formula (a211s) below, 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by formula (a211a) below, and 2,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA) represented by formula (a211i) below. Of these, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by formula (a211s) below is preferred.

[0067] [ka]

[0068] The compound represented by formula (a212) is p-phenylenebis(trimellitate)dianhydride (TAHQ).

[0069] The compound represented by formula (a213) is oxydiphthalic anhydride (ODPA), and specific examples thereof include 4,4'-oxydiphthalic anhydride (s-ODPA) represented by the following formula (a213s), 3,4'-oxydiphthalic anhydride (a-ODPA) represented by the following formula (a213a), and 3,3'-oxydiphthalic anhydride (i-ODPA) represented by the following formula (a213i). Of these, 4,4'-oxydiphthalic anhydride (s-ODPA) represented by the following formula (a213s) is preferred.

[0070] [ka]

[0071] The compound represented by formula (a214) is pyromellitic dianhydride (PMDA).

[0072] From the standpoints of high heat resistance and low residual stress, the structural unit (A21) preferably includes at least one selected from the group consisting of the structural unit (A211) and the structural unit (A212), and more preferably includes the structural unit (A211). The structural unit (A211) is preferred from the viewpoints of improving the heat resistance and thermal stability of the film and further reducing residual stress, while the structural unit (A212) is preferred from the viewpoints of decreasing YI and achieving better colorless transparency.

[0073] The proportion of the structural unit (A21) within the structural unit A2 is preferably 45 mol% or greater, more preferably 70 mol% or greater, even more preferably 90 mol% or greater, and particularly preferably 99 mol% or greater. There are no particular upper limits for this proportion, and it is generally 100 mol% or less. The structural unit (A21) need only include at least one selected from the structural units (A211) to (A214), and may be composed of only one selected from the structural units (A211) to (A214).

[0074] The proportion of the structural unit (A21) within the structural units A2i is preferably 45 mol% or greater, more preferably 70 mol% or greater, even more preferably 90 mol% or greater, and especially preferably 99 mol% or greater. There are no particular upper limits for this proportion, and it is generally 100 mol% or less. The structural unit (A21) need only include at least one selected from the structural units (A211) to (A214), and may be composed of only one selected from the structural units (A211) to (A214).

[0075] The proportion of the structural unit (A21) within the structural unit A2a is preferably 45 mol% or greater, more preferably 70 mol% or greater, even more preferably 90 mol% or greater, and particularly preferably 99 mol% or greater. There are no particular upper limits for this proportion, and it is generally 100 mol% or less. The structural unit (A21) need only include at least one selected from the structural units (A211) to (A214), and may be composed of only one selected from the structural units (A211) to (A214).

[0076] The structural unit A2 may contain a structural unit other than the structural unit (A21). The tetracarboxylic dianhydride that provides such a structural unit is not particularly limited, but examples thereof include aromatic tetracarboxylic dianhydrides such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 2,2',3,3'-benzophenonetetracarboxylic dianhydride; norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6, Examples of suitable tetracarboxylic dianhydrides include alicyclic tetracarboxylic dianhydrides such as 6"-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, and dicyclohexyltetracarboxylic dianhydride; and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride. Among these, aromatic tetracarboxylic dianhydrides are preferred. The structural units optionally contained in the structural unit A2 (that is, structural units other than the structural unit (A21)) may be one type alone, or two or more types in combination.

[0077] <Structural unit B2> Structural unit B2 is a structural unit derived from a diamine contained in the copolymer of the present invention, and includes a structural unit (B21) derived from a compound represented by the following formula (b21): When structural unit B2 includes structural unit (B21), excellent transparency can be achieved, and the properties of low residual stress and low retardation can both be achieved. The structural unit (B21) is included in the structural units derived from the structural unit B2i, which is derived from a diamine contained in an imide repeating structural unit.

[0078] [ka]

[0079] The compound represented by formula (b21) is the same as the compound represented by formula (b123) described above, and is 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA). When the structural unit B2 includes the structural unit (B21), the colorless transparency of the film can be improved.

[0080] It is preferable that the structural unit B2 further contains a structural unit (B22) derived from a compound represented by the following general formula (b22): When the structural unit B2 contains the structural unit (B22), the proportional limit can be reduced. The structural unit (B22) is preferably contained in the structural unit B2a derived from a diamine contained in the amic acid repeating structural unit.

[0081] [ka]

[0082] In formula (b22), Z 1 and Z 2 each independently represents a divalent aliphatic group or a divalent aromatic group which may contain an oxygen atom, and R 1 and R 2 each independently represents a monovalent aromatic group or a monovalent aliphatic group, R 3 and R 4 each independently represents a monovalent aliphatic group, and R 5 and R 6 each independently represents a monovalent aliphatic group or a monovalent aromatic group, m and n each independently represents an integer of 1 or more, and the sum of m and n represents an integer of 2 to 1,000. In formula (b22), the two or more different repeating units described in [ ] may be repeated in any form and order of random, alternating, or block, regardless of the order of [ ].

[0083] In formula (b22), Z 1 and Z 2The divalent aliphatic group or divalent aromatic group in may be substituted with a fluorine atom. Examples of the divalent aliphatic group include a divalent saturated or unsaturated aliphatic group having 1 to 20 carbon atoms and an aliphatic group containing an oxygen atom. The divalent aliphatic group preferably has 3 to 20 carbon atoms. Examples of the divalent saturated aliphatic group include alkylene groups having 1 to 20 carbon atoms, such as methylene, ethylene, propylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, and dodecamethylene. Examples of the divalent unsaturated aliphatic group include alkenylene groups having 2 to 20 carbon atoms, such as vinylene groups, propenylene groups, and alkenylene groups having an unsaturated double bond at the terminal. Examples of the aliphatic group containing an oxygen atom include an alkyleneoxy group and an aliphatic group having an ether bond. Examples of the alkyleneoxy group include a propyleneoxy group and a trimethyleneoxy group. Examples of the divalent aromatic group include an arylene group having 6 to 20 carbon atoms and an aralkylene group having 7 to 20 carbon atoms. Z 1 and Z 2 Specific examples of the arylene group having 6 to 20 carbon atoms in the formula include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4'-biphenylylene group, and a 2,6-naphthylene group. Z 1 and Z 2 As the alkyl group, a trimethylene group and a p-phenylene group are particularly preferred, and a trimethylene group is more preferred.

[0084] In formula (b22), R 1 ~R 6 The monovalent aliphatic group in the formula (I) includes a monovalent saturated or unsaturated aliphatic group. Examples of the monovalent saturated aliphatic group include an alkyl group having 1 to 22 carbon atoms, such as a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated aliphatic group include an alkenyl group having 2 to 22 carbon atoms, such as a vinyl group and a propenyl group. These groups may be substituted with a fluorine atom. R in equation (b22)1 , R 2 , R 5 and R 6 Examples of the monovalent aromatic group in the formula (I) include an aryl group having 6 to 20 carbon atoms, an aryl group having 7 to 30 carbon atoms and substituted with an alkyl group, and an aralkyl group having 7 to 30 carbon atoms. As the monovalent aromatic group, an aryl group is preferred, and a phenyl group is more preferred. R 1 and R 2 At least one of R is preferably a monovalent aromatic group. 1 and R 2 are more preferably both monovalent aromatic groups, and R 1 and R 2 More preferably, both are phenyl groups. R 3 and R 4 As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferred, and a methyl group is more preferred. R 5 and R 6 As the alkyl group, a monovalent aliphatic group is preferred, and a methyl group is more preferred.

[0085] As described above, among the compounds represented by the above general formula (b22), the compound represented by the following formula (b221) is preferred.

[0086] [ka] (In formula (b221), m and n have the same meanings as m and n in formula (b22), respectively, and the preferred ranges are also the same.)

[0087] In formula (b22) and formula (b221), m represents the number of repetitions of siloxane units to which at least one monovalent aromatic group is bonded, and n in formula (b22) and formula (b221) represents the number of repetitions of siloxane units to which a monovalent aliphatic group is bonded. In formula (b22) and formula (b221), m and n each independently represent an integer of 1 or greater, and the sum of m and n (m+n) represents an integer of 2 to 1000. The sum of m and n is preferably an integer of 3 to 500, more preferably an integer of 3 to 100, and even more preferably an integer of 3 to 50. The ratio of m / n in formula (b22) and formula (b221) is preferably 5 / 95 to 50 / 50, more preferably 10 / 90 to 40 / 60, and even more preferably 20 / 80 to 30 / 70.

[0088] The functional group equivalent (amine equivalent) of the compound represented by formula (b22) is preferably 150 to 5,000 g / mol, more preferably 400 to 4,000 g / mol, and even more preferably 500 to 3,000 g / mol. The functional group equivalent weight means the mass of the compound represented by formula (b22) per mole of the functional group (amino group).

[0089] Among the compounds represented by the general formula (b22) above, commercially available products include "X-22-9409," "X-22-1660B," "X-22-161A," and "X-22-161B," manufactured by Shin-Etsu Chemical Co., Ltd.

[0090] The proportion of the structural unit (B22) within the structural unit B is preferably within a range from 1 to 10 mol %, and more preferably from 2 to 5 mol %. The content of the polyorganosiloxane unit relative to the total of the structural units A2 and B2 is preferably 5 to 45 mass%, more preferably 7 to 40 mass%, and even more preferably 10 to 35 mass%. When the content of the polyorganosiloxane unit is within this range, low retardation and low residual stress can be achieved at the same time to an even greater extent. The polyorganosiloxane unit has the same meaning as the structural unit (B22), and the content of the polyorganosiloxane unit relative to the total of the structural unit A2 and the structural unit B2 is calculated from the mass ratio of the compound that provides the structural unit (B22), preferably the compound represented by formula (b22), to the total amount of raw materials that provide the structural unit A2 and the structural unit B2.

[0091] The structural unit B2i preferably contains the structural unit (B21), and the proportion of the structural unit (B21) in the structural unit B2i is preferably 45 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. There are no particular limitations on the upper limit of this proportion, and it is up to 100 mol%. The structural unit B2i may be composed solely of the structural unit (B21).

[0092] The structural unit B2a preferably contains the structural unit (B22), and the proportion of the structural unit (B22) in the structural unit B2a is preferably 45 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. There are no particular limitations on the upper limit of this proportion, and it is up to 100 mol%. The structural unit B2a may be composed solely of the structural unit (B22).

[0093] The structural unit B2 may include structural units other than the structural units (B21) and (B22). Diamines that provide such structural units include, but are not limited to, 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 3,4'-diaminodiphenyl ether, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-ine, aromatic diamines such as 1,4-diene-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and 1,4-bis(4-aminophenoxy)benzene, 9,9-bis(4-aminophenyl)fluorene; alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine. The structural units other than the structural units (B21) and (B22) optionally contained in the structural unit B2 may be of one type, or may be of two or more types.

[0094] [Production method of copolymer 2] Copolymer 2 can be produced by reacting a tetracarboxylic acid component consisting of a compound that provides structural unit A2i and a compound that provides structural unit A2a with a diamine component that includes a compound that provides structural unit B2i and a compound that provides structural unit B2a, and is preferably produced by a method including the following steps 1 and 2. Step 1: A step of reacting a compound that provides the structural unit A2i with a compound that provides the structural unit B2i to obtain an oligomer having imide repeating structural units. Step 2: A step of reacting the oligomer obtained in Step 1 with a compound that provides the structural unit B2a and a compound that provides the optional structural unit A2a to obtain a copolymer 2 having imide repeating structural units and amic acid repeating structural units. By the production method including the steps 1 and 2, copolymer 2 can be produced which is excellent in colorless transparency and heat resistance, and is capable of forming a film which is excellent in low retardation and low residual stress. The method for producing copolymer 2 will be described below.

[0095] <Tetracarboxylic acid component> The compound that provides the structural unit A2i and the compound that provides the structural unit A2a preferably include a compound that provides the structural unit (A21). Compounds that provide the structural unit (A21) include tetracarboxylic dianhydrides, which are compounds represented by formula (a211), formula (a212), formula (a213), and formula (a214), but are not limited to these. Derivatives thereof may also be used as long as they provide the same structural unit. Examples of such derivatives include tetracarboxylic acids corresponding to the respective tetracarboxylic dianhydrides and alkyl esters of the tetracarboxylic acids. Tetracarboxylic dianhydrides are preferred as compounds that provide the structural unit (A21).

[0096] The tetracarboxylic acid component preferably contains at least 45 mol% of a compound that provides structural unit (A21), more preferably at least 70 mol%, even more preferably at least 90 mol%, and especially preferably at least 99 mol%. There are no particular upper limits on this proportion, and it is up to 100 mol%. The compound that provides structural unit (A21) need only include at least one compound selected from the compounds that provide structural units (A211) to (A214), and may consist solely of any one compound selected from the compounds that provide structural units (A211) to (A214).

[0097] <Diamine component> The compound that provides the structural unit B2i preferably includes a compound that provides the structural unit (B21). Compounds that provide the structural unit (B21) include, but are not limited to, diamines; they may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamines. Diamines are preferred as compounds that provide the structural unit (B21).

[0098] The diamine component used as a raw material for the imide repeating structural unit preferably contains at least 45 mol%, more preferably at least 70 mol%, even more preferably at least 90 mol%, and particularly preferably at least 99 mol% of the compound that provides the structural unit (B21). There are no particular restrictions on the upper limit of this ratio, but it is up to 100 mol%. The diamine component used as a raw material for the imide repeating structural unit may consist solely of the compound that provides the structural unit (B21).

[0099] The compound that provides the structural unit B2a preferably includes a compound that provides the structural unit (B22). Compounds that provide the structural unit (B22) include, but are not limited to, diamines; they may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamines. Diamines are preferred as compounds that provide the structural unit (B22).

[0100] The diamine component used as a starting material for the amic acid repeating structural unit preferably contains at least 45 mol%, more preferably at least 70 mol%, even more preferably at least 90 mol%, and particularly preferably at least 99 mol% of the compound that provides the structural unit (B22). There are no particular restrictions on the upper limit of this ratio, but it is up to 100 mol%. The diamine component used as a starting material for the imide repeating structural unit may consist solely of the compound that provides the structural unit (B22).

[0101] The proportion of the compound that provides the structural unit (B22) in the entire amine component is preferably from 1 to 10 mol %, and more preferably from 2 to 5 mol %.

[0102] The ratio of the amount of the tetracarboxylic acid component to the amount of the diamine component used in the production of the copolymer 2 is preferably 0.9 to 1.1 moles of the diamine component per mole of the tetracarboxylic acid component. In step 1, by using an excess of either the tetracarboxylic acid component or the diamine component, the terminal of the resulting oligomer can be made to be a carboxylic acid or an amine.

[0103] <Solvent> The solvent used in producing copolymer 2 may be any solvent capable of dissolving the copolymer produced. Specific examples of the reaction solvent are as described for polyimide resin 1. Among the above reaction solvents, amide-based solvents or lactone-based solvents are preferred, amide-based solvents are more preferred, and N-methyl-2-pyrrolidone is even more preferred. The above reaction solvents may be used alone or in combination of two or more.

[0104] <Process 1> Step 1 is a step in which a compound that provides the structural unit A2i is reacted with a compound that provides the structural unit B2i to obtain an oligomer having imide repeating structural units. The tetracarboxylic acid component used in step 1 preferably contains a compound that provides the structural unit (A21), and the diamine component used in step 1 preferably contains a compound that provides the structural unit (B21). The ratio of the amounts of the components used in step 1 to the amount of the tetracarboxylic acid component used in step 1 is preferably 0.9 to 1.1 mol, more preferably 1.0 to 1.1 mol, relative to the diamine component.

[0105] There are no particular limitations on the method for reacting the tetracarboxylic acid component with the diamine component to obtain the oligomer in step 1, and any known method can be used. Specific reaction methods are as described for polyimide resin 1.

[0106] In the above imidization reaction, a known imidization catalyst can be used. Specific examples of the imidization catalyst are as described for the polyimide resin 1, and the preferred ranges are also the same.

[0107] The temperature of the imidization reaction is preferably 120 to 250° C., more preferably 160 to 200° C., from the viewpoint of the reaction rate and suppression of gelation, etc. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

[0108] The oligomer obtained in step 1 has imide repeating structural units having the structural unit A2i and the structural unit B2i. The oligomer obtained in step 1 preferably has carboxy groups at both ends of the main molecular chain. The carboxy group here includes derivatives. The above method provides a solution containing an oligomer dissolved in a solvent. The solution containing the oligomer obtained in step 1 may contain at least a portion of the components used as the tetracarboxylic acid component and the diamine component in step 1 as unreacted monomers, provided that the effects of the present invention are not impaired.

[0109] <Process 2> Step 2 is a step in which the oligomer obtained in Step 1 is reacted with a compound that provides the structural unit B2a and a compound that provides the optional structural unit A2a to obtain a copolymer 2 having imide repeating structural units and amic acid repeating structural units. The diamine component used in step 2 preferably contains a compound that provides the structural unit (B22). Alternatively, the unreacted diamine component remaining in the solution containing the oligomer obtained in step 1 may be used as the diamine component in step 2. In step 2, any tetracarboxylic acid component may be used, but it is preferable that the tetracarboxylic acid component contains a compound that provides the structural unit (A21). Furthermore, the unreacted tetracarboxylic acid component remaining in the solution containing the oligomer obtained in step 1 may be used as the diamine component in step 2. In step 1, when the oligomer has carboxy groups at both ends of the main chain of the molecular chain, step 2 may use only the diamine component.

[0110] There are no particular limitations on the method for reacting the oligomer obtained in step 1 with a compound that provides the structural unit B2a and a compound that provides the optional structural unit A2a to obtain the copolymer in step 2, and any known method can be used. Specific examples of the reaction method include (1) a method in which the oligomer obtained in step 1, a diamine component, a tetracarboxylic acid component, and a solvent are charged into a reactor and stirred at 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours. When the reaction is carried out at 80°C or less, the molecular weight of the copolymer obtained in step 2 does not vary depending on the temperature history during polymerization, and the progress of thermal imidization can be suppressed, so the copolymer can be produced stably.

[0111] Copolymer 2 is a copolymer having amic acid repeating structural units and imide repeating structural units, and is a product of a polyaddition reaction between the oligomer obtained in step 1 and a diamine component and an optional tetracarboxylic acid component in step 2. Copolymer 2 has imide repeating structural units formed in step 1 from a compound that provides structural unit A2i and a compound that provides structural unit B2i, and has amic acid repeating structural units formed in step 2 from a compound that provides structural unit B2a and a compound that provides optional structural unit A2a.

[0112] By the above method, a copolymer solution containing copolymer 2 dissolved in the solvent is obtained. The concentration of the copolymer in the resulting copolymer solution is usually in the range of 1 to 50% by mass, preferably 3 to 35% by mass, and more preferably 10 to 30% by mass.

[0113] From the viewpoint of the mechanical strength of the resulting polyimide film, the number average molecular weight of copolymer 2 is preferably 5,000 to 500,000. The number average molecular weight of copolymer 2 can be determined, for example, from a standard polymethyl methacrylate (PMMA) equivalent value measured by gel filtration chromatography.

[0114] <Metal films, semiconductor films, and insulating films> The laminate of the present invention preferably has at least one selected from the group consisting of a metal film, a semiconductor film, and an insulating film further laminated on the polyimide film, more preferably has at least one selected from the group consisting of a metal film and a semiconductor film further laminated on the polyimide film, even more preferably has a semiconductor film further laminated on the polyimide film, even more preferably has an insulating film and a semiconductor film further laminated on the polyimide film, and even more preferably has an insulating film and a semiconductor film further laminated on the polyimide film in this order. By laminating a metal film or a semiconductor film on the polyimide film, it is possible to produce a desired electronic device (conductive film) such as a touch sensor or an OLED on the polyimide film. The laminate of the present invention may have an insulating film between the polyimide film and the metal film or semiconductor film, and preferably has an insulating film, which is preferably a SiO2 film, and functions as a buffer film when forming the metal film or semiconductor film.

[0115] Preferred examples of the metal film include copper mesh and silver mesh. A preferred example of the semiconductor film is at least one selected from the group consisting of indium tin oxide (ITO), amorphous silicon, indium gallium zinc oxide (IGZO), and low temperature polysilicon (LTPS). On these metal or semiconductor films, another metal or semiconductor film may be further laminated. The thickness of the metal film or semiconductor film is not particularly limited, but is preferably 1 to 400 nm, more preferably 10 to 300 nm, and even more preferably 20 to 200 nm.

[0116] <Conductive film> The conductive film of the present invention can be obtained by peeling off the glass substrate from the laminate. That is, the conductive film can be obtained by peeling off the glass substrate from a laminate in which at least one film selected from the group consisting of a metal film, a semiconductor film, and an insulating film is further laminated on a polyimide film. However, to impart conductivity, the laminate is one in which either a metal film or a semiconductor film is laminated. After laminating at least one selected from the group consisting of a metal film, a semiconductor film, and an insulating film on a polyimide film to produce a laminate, the glass substrate may be immediately peeled off to obtain the conductive film, or the laminate may be stored and, if necessary, the glass substrate may be peeled off to obtain the conductive film. Storing the laminate is preferred because it improves the handleability of the conductive film during transportation.

[0117] The method for peeling and removing the glass substrate from the laminate is not particularly limited, but the laminate of the present invention allows the polyimide film to be easily and stably peeled from the glass substrate, and therefore, the laminate can be stably peeled without using a release layer or mechanically peeled without laser irradiation.

[0118] The conductive film thus obtained can be used for a transparent electrode, and the laminate of the present invention is preferably used as a laminate for forming a transparent electrode.

[0119] [Method of manufacturing laminate] The method for producing a laminate of the present invention is a method for producing a laminate comprising the steps of: (a) a glass substrate on which a polyimide film is adhered; (b) a glass substrate on which a polyimide film is adhered; and (c) a polyimide film on which the polyimide film is adhered; 2There are no particular limitations on the production method as long as it can produce a laminate in which the proportional limit of the polyimide film is 10 to 45 MPa or less, but the following method is preferred. That is, a preferred method for producing a laminate of the present invention is a method for producing a laminate in which at least one selected from polyimide varnish, polyamic acid varnish, and varnish obtained by dissolving a copolymer having imide repeating structural units and amidic acid repeating structural units in an organic solvent is applied to a glass substrate, followed by drying to form a polyimide film, and the method includes at least one step selected from a glass substrate alkali cleaning step and a glass substrate ozone treatment step prior to applying the varnish, and a step of adjusting the proportional limit of the resulting polyimide film to be 10 to 45 MPa.

[0120] In the method for producing a laminate of the present invention, the surface free energy of the contact surface between the glass substrate and the polyimide film is set to 65 mJ / m 2 To achieve the following, it is preferable to have at least one step selected from a glass substrate alkali cleaning step and a glass substrate ozone treatment step before applying the polyimide varnish, more preferably to have both a glass substrate alkali cleaning step and a glass substrate ozone treatment step, and even more preferably to have both steps in this order. Before cleaning, the surface free energy of the contact surface was 65 mJ / m 2 However, since the surface free energy of the contact surface varies depending on the location, it is preferable to perform this step in order to eliminate the variation and make the surface free energy of the entire contact surface uniform. Furthermore, when multiple glass substrates are used, it is preferable to perform this step so that all of the glass substrates satisfy the above range.

[0121] As mentioned above, the type of glass used in this manufacturing method is not particularly limited, and examples that can be used include alkali-free glass (borosilicate glass), alkali glass, soda glass, non-fluorescent glass, phosphate glass, borate glass, and quartz.

[0122] This process preferably first includes a glass substrate alkaline cleaning step in which the glass substrate is cleaned with an alkali. The alkali used is preferably potassium hydroxide. The cleaning method preferably involves immersing the glass substrate in an alkaline aqueous solution, rinsing with water, and drying. The concentration of the alkali in the alkaline aqueous solution is preferably 0.1 to 1% by mass. The washing is preferably carried out at a temperature of 20 to 30°C, and more preferably at 23 to 25°C.

[0123] Next, it is preferable to have a glass substrate ozone treatment step, which is an ozone treatment. The ozone treatment is carried out by irradiating the surface of the glass substrate with ultraviolet rays. The irradiation conditions are a cumulative irradiation dose of 150 to 250 mJ / cm 2 is preferably 190 to 200 mJ / cm 2 It is more preferable that:

[0124] It is also preferable to provide a step of adjusting the proportional limit of the resulting polyimide film to 10 to 45 MPa. If a solution of a polyimide resin or its precursor, polyamic acid, or a copolymer having imide repeating structural units and amidic acid repeating structural units is applied directly to a glass substrate and dried to obtain a polyimide film within the range of the proportional limit, this step is not necessary. As described above, there are no limitations on the method for adjusting the proportional limit of a polyimide film consisting essentially of a polyimide resin to 10 to 45 MPa, and any method can be used that adjusts the monomer composition, molecular weight, etc. of the polyimide resin. However, using a method in which the structural unit (B22) is included in the structural units of the polyimide resin is preferred, as this makes it possible to easily adjust the proportional limit of the polyimide film to be within the above range.

[0125] This step of adjusting the proportional limit of the resulting polyimide film to 10 to 45 MPa is preferably a step of adding a resin additive to the varnish. That is, in this step, it is preferable to add a resin additive to at least one varnish selected from polyimide varnish, polyamic acid varnish, and varnish obtained by dissolving a copolymer having imide repeating structural units and amic acid repeating structural units in an organic solvent.

[0126] Preferred resin additives include phosphate ester compounds, amino-modified silicone oils, silicone-containing polymers, acrylic polymers, and fluorine-containing polymers. Among these, at least one selected from the group consisting of a phosphate ester compound, an amino-modified silicone oil, and a silicone-containing polymer is more preferred. From the viewpoint of reducing the peel strength of the laminate, it is preferred to use two or more resin additives in combination, more preferred to use a phosphate ester compound and a silicone-containing polymer in combination, and even more preferred to use a phosphate ester compound, an amino-modified silicone oil, and a silicone-containing polymer in combination. As the phosphate ester compound, acidic phosphate ester compounds are preferred, and dibutyl phosphate is more preferred. By including the additive, it is possible to reduce the proportional limit, and the proportional limit can be set within the above range. The content of the additive is preferably 0.01 to 0.7 mass %, more preferably 0.05 to 0.5 mass %, and even more preferably 0.05 to 0.2 mass %, relative to the polyimide resin, polyamic acid varnish, or copolymer having imide repeating structural units and amic acid repeating structural units contained in the varnish. In particular, when a phosphate ester compound is used, the content is preferably 0.01 to 0.7 mass %, more preferably 0.01 to 0.3 mass %, and even more preferably 0.01 to 0.1 mass %, relative to the polyimide resin, polyamic acid varnish, or copolymer having imide repeating structural units and amidic acid repeating structural units contained in the varnish. Furthermore, when an amino-modified silicone oil is used, the amount is preferably 0.3 to 0.7 mass %, more preferably 0.3 to 0.6 mass %, and even more preferably 0.3 to 0.5 mass %, relative to the polyimide resin, polyamic acid varnish, or copolymer having imide repeating structural units and amidic acid repeating structural units contained in the varnish. Furthermore, when a silicone-containing polymer is used, the content is preferably 0.05 to 0.7 mass %, more preferably 0.05 to 0.3 mass %, and even more preferably 0.05 to 0.1 mass %, of the polyimide resin, polyamic acid varnish, or copolymer having imide repeating structural units and amidic acid repeating structural units contained in the varnish.

[0127] In the method for producing a laminate of the present invention, the method for forming a polyimide film is not particularly limited, and any known method can be used, such as a method in which a polyimide varnish, a polyamic acid varnish, or a varnish of a copolymer having imide repeating structural units and amic acid repeating structural units is applied to a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film, and then organic solvents such as reaction solvents and diluent solvents contained in the varnish are removed by heating.

[0128] Examples of the method for applying the varnish include known methods such as spin coating, slit coating, blade coating, etc. Among these, slit coating is preferred from the viewpoint of workability, as it controls intermolecular orientation and improves chemical resistance. A preferred method for removing the organic solvent contained in the varnish by heating is to evaporate the organic solvent at a temperature of 150°C or less to make the varnish tack-free, and then dry it at a temperature equal to or higher than the boiling point of the organic solvent used (preferably 200 to 500°C, although there are no particular limitations). Drying is also preferred in an air or nitrogen atmosphere. The pressure of the drying atmosphere may be reduced, normal, or increased.

[0129] <Polyimide varnish> The polyimide varnish is prepared by dissolving a polyimide resin in an organic solvent. That is, the polyimide varnish contains a polyimide resin and an organic solvent, and the polyimide resin is dissolved in the organic solvent. As the polyimide resin, the above-mentioned polyimide resins are preferred. The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the compounds described above as reaction solvents used in the production of polyimide resins, either alone or in combination of two or more. The polyimide varnish may be a polyimide solution itself in which a polyimide resin obtained by polymerization is dissolved in a reaction solvent, or may be a polyimide solution to which a dilution solvent is further added.

[0130] By dissolving a solvent-soluble polyimide resin in a solvent, a highly concentrated varnish that is stable at room temperature can be obtained. The polyimide varnish preferably contains 5 to 40 mass % of polyimide resin, more preferably 10 to 30 mass %. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, more preferably 1.5 to 100 Pa·s, and even more preferably 2 to 100 Pa·s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer. The polyimide varnish may also contain various additives other than the above-mentioned resin additives, such as inorganic fillers, adhesion promoters, flame retardants, ultraviolet stabilizers, leveling agents, antifoaming agents, fluorescent brightening agents, crosslinking agents, polymerization initiators, photosensitizers, and adhesion promoters, within the range that does not impair the required properties of the polyimide film. The method for producing the polyimide varnish is not particularly limited, and known methods can be applied.

[0131] <Polyamic acid varnish> The polyimide film can also be produced using a polyamic acid varnish prepared by dissolving polyamic acid in an organic solvent. The polyamic acid contained in the polyamic acid varnish is a precursor of a polyimide resin. Therefore, it is preferable that the polyamic acid be obtained by polymerizing a compound that provides the structural unit constituting the polyimide resin. The final product, a polyimide resin, is obtained by imidizing (dehydrating and cyclizing) the polyamic acid. As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish can be used. In the present invention, the polyamic acid varnish may be a polyamic acid solution itself obtained by subjecting a tetracarboxylic acid component and a diamine component to a polyaddition reaction in a reaction solvent, or may be a polyamic acid solution to which a dilution solvent has been further added.

[0132] The method for producing a polyimide film using the polyamic acid varnish is not particularly limited, and any known method can be used. For example, the polyamic acid varnish is applied to a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film, and organic solvents such as a reaction solvent and a dilution solvent contained in the varnish are removed by heating to obtain a polyamic acid film, and the polyamic acid in the polyamic acid film is imidized by heating, thereby producing a polyimide film. The heating temperature when the polyamic acid varnish is dried to obtain a polyamic acid film is preferably 50 to 120°C. The heating temperature when the polyamic acid is imidized by heating is preferably 200 to 400°C. The imidization method is not limited to thermal imidization, and chemical imidization can also be applied.

[0133] <Copolymer varnish> The polyimide film can also be produced using a copolymer varnish (hereinafter also referred to as copolymer varnish) obtained by dissolving a copolymer having imide repeating structural units and amide acid repeating structural units (hereinafter also referred to as copolymer) in an organic solvent. The copolymer varnish is a precursor of a polyimide resin, a copolymer having imide repeating structural units and amic acid repeating structural units, dissolved in an organic solvent. That is, the copolymer varnish contains a copolymer and an organic solvent, and the copolymer is dissolved in the organic solvent. As the copolymer, a copolymer having the above-mentioned imide repeating structural unit and amic acid repeating structural unit is preferred, and the above-mentioned copolymer 2 is more preferred. The organic solvent is not particularly limited as long as it dissolves the copolymer, but it is preferable to use the above-mentioned compounds as the solvent used in producing the copolymer, either alone or in combination of two or more. The copolymer varnish may be the above-mentioned copolymer solution itself, or may be the copolymer solution to which a diluting solvent is further added.

[0134] The copolymer varnish may further contain an imidization catalyst and a dehydration catalyst from the viewpoint of efficiently proceeding with the imidization of the amide acid moieties in the copolymer. The imidization catalyst may be an imidization catalyst having a boiling point of 40°C or higher and 180°C or lower, and an amine compound having a boiling point of 180°C or lower is preferred. If the imidization catalyst has a boiling point of 180°C or lower, there is no risk of the film being discolored and its appearance being impaired when dried at high temperatures after film formation. Furthermore, if the imidization catalyst has a boiling point of 40°C or higher, there is no risk of the film volatilizing before imidization has progressed sufficiently. Examples of amine compounds suitable for use as imidization catalysts include pyridine and picoline. The above imidization catalysts may be used alone or in combination of two or more. Examples of the dehydration catalyst include acid anhydrides such as acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride; carbodiimide compounds such as dicyclohexylcarbodiimide; etc. These may be used alone or in combination of two or more.

[0135] The copolymer contained in the copolymer varnish is soluble in a solvent, allowing for a highly concentrated varnish. The copolymer varnish preferably contains 5 to 40 mass %, more preferably 10 to 30 mass %, of copolymer 2. The viscosity of the copolymer varnish is preferably 0.1 to 100 Pa·s, more preferably 0.1 to 20 Pa·s. The viscosity of the copolymer varnish is a value measured at 25°C using an E-type viscometer. Furthermore, the copolymer varnish may contain various additives other than the above-mentioned resin additives, such as inorganic fillers, adhesion promoters, flame retardants, ultraviolet stabilizers, leveling agents, defoamers, fluorescent brighteners, crosslinking agents, polymerization initiators, photosensitizers, and adhesion promoters, within the range that does not impair the required properties of the polyimide film. The method for producing the varnish is not particularly limited, and known methods can be applied.

[0136] The heating temperature when the copolymer varnish is dried to obtain a copolymer film is preferably 50 to 150° C. The heating temperature when the copolymer is imidized by heating can be selected from the range of preferably 200 to 500° C., more preferably 250 to 450° C., and even more preferably 300 to 400° C. The heating time is usually 1 minute to 6 hours, preferably 5 minutes to 2 hours, and more preferably 15 minutes to 1 hour. Examples of the heating atmosphere include air gas, nitrogen gas, oxygen gas, hydrogen gas, and a nitrogen / hydrogen mixed gas. In order to suppress discoloration of the resulting polyimide resin, nitrogen gas having an oxygen concentration of 100 ppm or less and a nitrogen / hydrogen mixed gas having a hydrogen concentration of 0.5% or less are preferred. The imidization method is not limited to thermal imidization, and chemical imidization can also be applied. [Example]

[0137] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples in any way.

[0138] In the examples and comparative examples, the physical properties were measured by the following methods. (1) Film thickness The thickness of the film was measured using a laser microscope (manufactured by Keyence Corporation).

[0139] (2) Proportional limit of polyimide film The polyimide film was peeled off from the two-layer laminate obtained in the process of producing the four-layer laminate of the Examples and Comparative Examples, and the film was cut into pieces of 10 mm x 70 mm using a cutting cutter to obtain test pieces. In the Comparative Example, part of the laminate was destroyed, but the peeled part was used to obtain test pieces. The proportional limit was measured in accordance with JIS K7127:1999 using a tensile testing machine "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. The distance between chucks was 50 mm, the test piece size was 10 mm x 70 mm, and the test speed was 20 mm / min. From the recorded stress-strain curve, the maximum stress at which stress and strain were proportional was taken as the proportional limit. The proportional limits of the polyimide films obtained as described above are shown in Table 2.

[0140] (3) Surface free energy of glass substrate The surface free energy of the glass substrates used in the examples and comparative examples was determined as follows. First, using water, ethylene glycol, and diiodomethane as probe liquids, an automatic contact angle meter (trade name DM300, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle of each liquid on the glass substrate surface at 23°C by the sessile drop method. The probe liquid, glass substrate, and atmosphere inside the device were kept at 23°C, and the contact angle was measured 2 seconds after the probe liquid was dropped. The contact angles on the uncleaned glass substrate described below were 35.4° for water, 23.4° for ethylene glycol, and 48.1° for diiodomethane, and the contact angles on the cleaned glass substrate described below were 35.4° for water, 29.6° for ethylene glycol, and 55.6° for diiodomethane. The contact angle values ​​for each liquid were substituted into the following formula (1) to calculate γSd, γSp, and γSh. In formula (1), the values ​​for γLd, γLp, γLh, and γL for each liquid were taken from the values ​​described in the following literature (Patent: Proceedings of the 2012 Spring Meeting of the Japan Precision Industry Association, 2012, L69, p. 975). Next, the surface free energy γS of the solid was calculated using formula (2), and this was used as the surface free energy of the glass substrate. The surface free energies of the glass substrates obtained as described above are shown in Table 2.

[0141] (γSd × γLd) 1 / 2 +(γSp × γLp) 1 / 2 +(γSh × γLh) 1 / 2 =γL(1+cosθ) / 2 (1) (In equation (1), γSd is the dispersion force component of van der Waals forces in a solid, γSp is the interfacial interaction force (polar component) due to intermolecular forces based on polarity in a solid, γSh is the hydrogen bonding interaction force (hydrogen bonding component) in a solid, γLd is the dispersion force component of van der Waals forces in a liquid, γLp is the interfacial interaction force (polar component) due to intermolecular forces based on polarity in a liquid, γLh is the hydrogen bonding interaction force (hydrogen bonding component) in a liquid, γL is the surface free energy of the liquid, and θ is the contact angle of the liquid.)

[0142] γS=γSd+γSp+γSh (2) (In equation (2), γS represents the surface free energy of the solid.)

[0143] The above formula (1) was created from the Young-Dupre formula, Dupre formula, and extended Fowkes formula below. (Young-Dupre equation) WSL=γL(1+cosθ) (In the formula, WSL is the work of adhesion, and γL and θ are as defined above.)

[0144] (Dupre's formula) γS+γL=WSL+γSL (In the formula, γSL is the interfacial free energy, and γS, γL, and WSL are as defined above.)

[0145] (Extended Fowkes formula) γSL=γS+γL-{2(γSd×γLd) 1 / 2 +2(γSp×γLp) 1 / 2 +2(γSh×γLh) 1 / 2} (In the formula, γSL, γS, γL, γSd, γLd, γSp, γLp, γSh, and γLh are as defined above.)

[0146] (4) Peelability The releasability when peeling the laminate from the glass substrate was evaluated according to the following criteria. The laminate was peeled off from the glass substrate using the 90° peel test method used in (5) Peel strength evaluation, which will be described later. ◯: The entire laminate was peeled off from the glass substrate ×: When peeling the laminate from the glass substrate, the adhesion between the glass substrate and the laminate was strong, and part of the laminate was broken.

[0147] (5) Peel strength A 90° peel test was carried out based on JIS K6854-1 to measure the peel strength between the polyimide film and the glass substrate. The peel strength was measured five times, and the average value was taken as the peel strength.

[0148] The tetracarboxylic acid component, diamine component, other components, and their abbreviations used in the production examples are as follows: <Tetracarboxylic acid component> HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Company, Inc.; compound represented by formula (a11)) ODPA: 4,4'-oxydiphthalic anhydride (manufactured by Manac Corporation; compound represented by formula (a12)) s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation, a compound represented by formula (a211s)) <Diamine component> 3,3'-DDS: 3,3'-diaminodiphenyl sulfone (manufactured by Seika Corporation; compound represented by formula (b11)) HFBAPP: 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (manufactured by Seika Corporation; compound represented by formula (b121)) BAPS: bis[4-(4-aminophenoxy)phenyl]sulfone (manufactured by Seika Corporation; compound represented by formula (b122)) 6FODA: 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (manufactured by ChinaTech (Tianjin) Chemical Co., Ltd., a compound represented by formula (b21)) X-22-1660B-3: silicone oil modified at both ends with amino groups (manufactured by Shin-Etsu Chemical Co., Ltd., a compound represented by formula (b22) (functional group equivalent: 2200 g / mol or 2170 g / mol)) <Other> GBL: γ-butyrolactone (Mitsubishi Chemical Corporation) TEA: Triethylamine (Kanto Chemical Co., Ltd.) DMAc: N,N-dimethylacetamide (Mitsubishi Gas Chemical Company, Inc.)

[0149] <Production of Polyimide Varnish and Copolymer Varnish> Manufacturing Example 1 23.530 g (0.094 mol) of 3,3'-DDS, 12.247 g (0.024 mol) of HFBAPP, and 62.820 g of GBL were placed in a 300 mL five-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean-Stark condenser, a thermometer, and a glass end cap, and the mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 70°C to obtain a solution. To this solution, 24.216 g (0.108 mol) of HPMDA, 3.721 g (0.012 mol) of ODPA, and 15.705 g of GBL were added all at once, followed by the addition of 0.596 g of TEA as an imidization catalyst. The mixture was heated with a mantle heater, and the temperature in the reaction system was raised to 190°C over approximately 20 minutes. The components distilled off were collected, and the temperature in the reaction system was maintained at 190°C and refluxed for 5 hours while adjusting the rotation speed according to the increase in viscosity. Thereafter, 161.475 g of GBL was added so that the solid content concentration was 20 mass %, and the temperature inside the reaction system was cooled to 100° C., and then the mixture was further stirred for about 1 hour to be homogenized, thereby obtaining Polyimide Varnish 1.

[0150] Manufacturing Example 2 A 300 mL five-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean-Stark condenser, a thermometer, and a glass end cap was charged with 13.845 g (0.056 mol) of 3,3'-DDS, 24.115 g (0.056 mol) of BAPS, and 41.903 g of GBL, and the mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 70°C to obtain a solution. To this solution, 22.499 g (0.100 mol) of HPMDA, 3.459 g (0.011 mol) of ODPA, and 12.804 g of GBL were added all at once, followed by the addition of 0.564 g of TEA as an imidization catalyst. The mixture was heated with a mantle heater, and the temperature in the reaction system was raised to 190°C over approximately 20 minutes. The components distilled off were collected, and the temperature in the reaction system was maintained at 190°C and refluxed for approximately 5 hours while adjusting the rotation speed according to the increase in viscosity. Thereafter, 175.981 g of GBL was added so that the solid content concentration was 20% by mass, and the temperature inside the reaction system was cooled to 100° C., followed by further stirring for about 1 hour to homogenize, whereby Polyimide Varnish 2 was obtained.

[0151] Manufacturing Example 3 21.127 g (0.063 mol) of 6FODA and 94.051 g of DMAc were placed in a 300 mL five-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean-Stark condenser, a thermometer, and a glass end cap, and the mixture was stirred at 200 rpm under a nitrogen atmosphere at an internal temperature of 25°C to obtain a solution. To this solution, 19.195 g (0.065 mol) of s-BPDA and 23.513 g of DMAc were added all at once, and the mixture was heated with a mantle heater until the temperature in the reaction system reached 50°C over approximately 20 minutes. The components distilled off were collected, and the temperature in the reaction system was maintained at 50°C while adjusting the rotation speed according to the increase in viscosity, followed by reflux for approximately 5 hours. Subsequently, 139.190 g of DMAc was added, and the temperature in the reaction system was cooled to 25°C, yielding a solution containing an oligomer having imide repeating structural units. A mixture of 10.063 g (0.002 mol) of X-22-1660B-3 dissolved in 15.466 g of DMAc was added to the resulting solution, and the mixture was stirred for another hour to obtain a copolymer varnish 3 containing a copolymer (PI-b-PAA) with a solids concentration of approximately 20% by mass. Here, the copolymer having imide repeating structural units and amic acid repeating structural units is referred to as "PI-b-PAA." The compositions of the polyimide resins and copolymers contained in the varnishes obtained in Production Examples 1 to 3 are shown in Table 1.

[0152] [Table 1]

[0153] The additives and glass substrates used in the examples and comparative examples are as follows. <Resin additives> Resin additive 1: Dibutyl phosphate (DBP, Johoku Chemical Industry Co., Ltd.) Resin additive 2: Amino-modified silicone oil (X-22-9409, manufactured by Shin-Etsu Chemical Co., Ltd.) Resin additive 3: Silicone-containing polymer (Polyflow KL-700, Kyoeisha Chemical Co., Ltd.) <Other additives> Leveling agent: BYK-378 (BYK Japan Co., Ltd.) Adhesion promoter: BYK-4513 (BYK Japan Co., Ltd.) <Glass substrate> Unwashed glass substrate: non-alkali glass (product name: AN-100, dimensions: 100 mm x 100 mm x 0.7 mm, manufactured by AGC Inc.) was used as is. Cleaned glass substrate: The alkali-free glass AN-100 was cleaned by chemical treatment and ozone treatment. For the chemical treatment, the glass was immersed in an aqueous potassium hydroxide solution (concentration: 0.1% by mass) at 23°C for 3 minutes, then removed and rinsed with ion-exchanged water, and the glass surface was thoroughly dried at room temperature (23°C). Next, for the ozone treatment, ultraviolet light (cumulative irradiation dose: 190 to 200 mJ / cm) was applied to the glass surface. 2 The adhesions were decomposed and removed by irradiating the surface with light for 8 seconds.

[0154] <Manufacturing of laminate> Example 1 The polyimide varnish 1 obtained in Production Example 1 was mixed with 0.1 mass % of a leveling agent relative to the polyimide resin in the varnish, 0.1 mass % of resin additive 1 relative to the polyimide resin in the varnish, 0.5 mass % of resin additive 2 relative to the polyimide resin in the varnish, and 0.1 mass % of resin additive 3 relative to the polyimide resin in the varnish, and the mixture was then applied by spin coating to a cleaned glass substrate to obtain a varnish-coated substrate. The resulting varnish-coated substrate was held at 80°C for 20 minutes using a hot plate, and then heated at 260°C for 30 minutes in a hot air dryer under an air atmosphere to evaporate the solvent, yielding a two-layer laminate (glass / polyimide film). Furthermore, a 30 nm thick SiO2 film was formed on the polyimide film of the two-layer laminate by sputtering, and a 120 nm thick ITO (indium tin oxide) film was formed on top of that to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0155] Comparative Example 1 A leveling agent was mixed with the polyimide varnish 1 obtained in Production Example 1 so that the amount of the leveling agent was 0.1% by mass relative to the polyimide resin in the varnish, and then the mixture was applied to a cleaned glass plate by spin coating to obtain a varnish-coated substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0156] Example 2 The polyimide varnish 2 obtained in Production Example 2 was mixed with 0.1 mass % of a leveling agent relative to the polyimide resin in the varnish, 0.1 mass % of resin additive 1 relative to the polyimide resin in the varnish, and 0.1 mass % of resin additive 3 relative to the polyimide resin in the varnish, and then the mixture was applied by spin coating to a cleaned glass plate to obtain a varnish-coated substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0157] Comparative Example 2 A leveling agent was mixed with the polyimide varnish 2 obtained in Production Example 2 so that the amount of the leveling agent was 0.1% by mass relative to the polyimide resin in the varnish, and then the mixture was applied to an unwashed glass substrate by spin coating to obtain a varnished substrate. Except for this, the obtained varnished substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0158] Comparative Example 3 A leveling agent was mixed with the polyimide varnish 2 obtained in Production Example 2 so that the amount of the leveling agent was 0.1% by mass relative to the polyimide resin in the varnish, and then the mixture was applied to a cleaned glass plate by spin coating to obtain a varnish-coated substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0159] Example 3 A leveling agent was mixed with the copolymer varnish 3 obtained in Production Example 3 so that the amount of the leveling agent was 0.1% by mass relative to the copolymer in the varnish, and then the mixture was applied to a cleaned glass plate by spin coating to obtain a varnish-coated substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0160] Example 4 A leveling agent and an adhesion promoter were mixed with the copolymer varnish 3 obtained in Production Example 3 so that the amount was 0.1 mass % relative to the copolymer in the varnish, and then the mixture was applied to a cleaned glass plate by spin coating to obtain a varnish-coated substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0161] Comparative Example 4 A leveling agent was mixed with the copolymer varnish 3 obtained in Production Example 3 so that the amount of the leveling agent was 0.1% by mass relative to the copolymer in the varnish, and then the mixture was applied by spin coating to an unwashed glass plate to obtain a varnished substrate. Except for this, the obtained varnish-coated substrate was treated in the same manner as in Example 1 to obtain a four-layer laminate (glass / polyimide film / SiO2 film / ITO film).

[0162] The laminate obtained above was evaluated for peelability and peel strength as described above. The results are shown in Table 2.

[0163] [Table 2]

[0164] The results in Table 2 show that the laminates of the examples enable the polyimide film to be stably peeled from the glass substrate without using a release layer.

Claims

1. A laminate in which a polyimide film is adhered to a glass substrate, wherein the surface free energy of the contact surface of the glass substrate with the polyimide film is 65 mJ / m 2 or less, and the proportional limit of the polyimide film is 10 to 45 MPa; the polyimide resin of the polyimide film has a structural unit A1 derived from a tetracarboxylic dianhydride and a structural unit B1 derived from a diamine, The structural unit A1 includes a structural unit (A11) derived from a compound represented by the following formula (a11) and a structural unit (A12) derived from a compound represented by the following formula (a12): A laminate, in which the structural unit B1 includes a structural unit (B11) derived from a compound represented by the following formula (b11): 【Chemistry 1】 【Chemistry 2】

2. The peel strength of the polyimide film from the glass substrate is 20 gf / cm or less. The laminate according to claim 1 .

3. 3. The laminate according to claim 1, wherein the polyimide film has a thickness of 3 to 20 μm.

4. 4. The laminate according to claim 1, wherein at least one film selected from the group consisting of a metal film, a semiconductor film, and an insulating film is further laminated on the polyimide film.

5. 5. The laminate according to claim 4, wherein the semiconductor film is at least one selected from the group consisting of indium tin oxide, amorphous silicon, indium gallium zinc oxide, and low-temperature polysilicon.

6. 1. A method for producing a laminate, comprising: applying at least one varnish selected from the group consisting of polyimide varnish, polyamic acid varnish, and varnish obtained by dissolving a copolymer having imide repeating structural units and amic acid repeating structural units in an organic solvent onto a glass substrate; and drying the varnish to form a polyimide film, the polyimide resin of the polyimide film has a structural unit A1 derived from a tetracarboxylic dianhydride and a structural unit B1 derived from a diamine, The structural unit A1 includes a structural unit (A11) derived from a compound represented by the following formula (a11) and a structural unit (A12) derived from a compound represented by the following formula (a12): The structural unit B1 includes a structural unit (B11) derived from a compound represented by the following formula (b11): The method for producing a laminate includes at least one step selected from a glass substrate alkali cleaning step and a glass substrate ozone treatment step before applying the varnish, and a step of adjusting the proportional limit of the resulting polyimide film to be 10 to 45 MPa. 【Transformation 3】 【Chemistry 4】

7. 7. The method for producing a laminate according to claim 6, wherein the step of adjusting the proportional limit of the resulting polyimide film to 10 to 45 MPa is a step of adding a resin additive to the varnish.

8. The method for producing a laminate according to claim 7, wherein the resin additive is at least one selected from the group consisting of a phosphate ester compound, an amino-modified silicone oil, and a silicone-containing polymer.

9. A conductive film obtained by peeling off the glass substrate from the laminate according to claim 4 or 5.

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