Method for producing a polymer, method for producing a polymer film using the same, and method for producing a laminate

Abstract

Provided is a polymer film manufacturing method that makes it possible to suppress deterioration in the physical properties and appearance of a polymer film due to gel defects, while also reducing problems such as coloration and an increase in the peel strength thereof. Also provided are: a laminate manufacturing method that makes it possible to suppress gel defects, while reducing warpage of a laminate and warpage of a resin layer after peeling; and a flexible substrate manufacturing method utilizing said method. A polymer production method according to the present invention is characterized by including: a step for applying a solution containing a polymer precursor onto a support; and a step for causing a chemical reaction of the polymer precursor, wherein a reaction accelerator for promoting the chemical reaction of the polymer precursor is provided in advance on the surface of the support. The present invention also relates to a polymer film manufacturing method employing said method, a laminate manufacturing method, and a flexible substrate manufacturing method utilizing said laminate manufacturing method.

Description

[Technical Field]

[0001] This invention relates to a method for producing a polymer using a solution containing a polymer precursor such as polyamic acid, a method for producing a polymer film using the same, and a method for producing a laminate. Furthermore, this invention relates to a method for producing a flexible substrate using the method for producing the laminate. [Background technology]

[0002] Due to its heat resistance and insulating properties, polyimide film is used as a base film for flexible printed circuit boards (hereinafter also referred to as FPC). Polyimide film is generally produced by either a thermal imidation method, in which a green film obtained by coating an organic solvent solution of polyamic acid, a precursor, onto a support and evaporating some of the solvent is heat-treated, or a chemical imidation method, in which an imidation accelerator is added to an organic solvent solution of polyamic acid, and then a green film is similarly prepared and heat-treated.

[0003] Of these two methods, the chemical imidation method is sometimes preferred because it facilitates the acceleration of the imidation reaction, making it easier to increase the production rate, and because it can yield films with higher molecular weight and greater toughness.

[0004] However, because the chemical imidation method involves the addition of an imidation accelerator, it is prone to generating fine particles of polyimide where imidation proceeds locally (hereinafter referred to as "gel-like material," and the resulting defects as "gel defects"). If these gel defects are present in the film, not only will the appearance be poor, but they can also become the starting point for fracture when stress is applied to the film, cause surface irregularities, and constitute defects in the FPC (Flexible Printed Circuit).

[0005] The gel defects described above can be improved by keeping the polyamic acid solution and the imidization accelerator at low temperatures to suppress rapid imidization, and by increasing the rotation speed of the stirring mixer used to mix the two to improve stirring efficiency. However, increasing the stirring speed also leads to an increase in the heat generated by stirring, so there is naturally a limit to how high the rotation speed can be increased.

[0006] In response to this, attempts have been made to reduce gel defects in the film by filtering a solution obtained by mixing a polyamic acid solution with an imidization accelerator (see Patent Document 1).

[0007] Incidentally, conventionally, in the fields of flat panel displays (FPDs) such as liquid crystal displays (LCDs), plasma display panels (PDPs), and organic light-emitting diodes (OLEDs), as well as electronic devices such as electronic paper, electronic elements have been formed on substrates made of inorganic materials such as glass substrates (inorganic substrates). However, inorganic substrates are rigid and lack flexibility, which presents a problem in that they are difficult to make flexible.

[0008] Therefore, a method has been proposed that uses organic polymer materials such as polyimide, which are flexible and heat-resistant, as substrates. Specifically, a technology has been put into practical use in which a flexible, highly heat-resistant resin layer is laminated on an inorganic substrate used as a carrier, and this highly heat-resistant resin layer is used as a substrate or wiring board for forming electronic elements. Here, for example, if a glass substrate with excellent light transmittance is used as the inorganic substrate, the inspection process when forming electronic elements and when creating wiring boards becomes easier, and there is the advantage that existing equipment for producing flexible devices that form electronic elements on glass substrates can be directly repurposed.

[0009] Furthermore, when manufacturing a laminate having a polyimide resin layer on a support such as an inorganic substrate, the chemical imidation method can be preferably used, similar to the case of polyimide films. However, this method has the problem of being prone to gel defects. If these gel defects are present in the resin layer, they not only result in poor appearance, but they can also become the starting point for fracture when stress is applied to the resin layer, cause surface irregularities, and lead to defects in the display manufacturing process. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2002-348388 [Overview of the project] [Problems that the invention aims to solve]

[0011] However, the invention described in Patent Document 1 merely removes the gel-like substance with a filter and does not fundamentally suppress its generation. Therefore, if a large amount of gel-like substance is generated, the filter becomes clogged, making long-term continuous production of the film difficult.

[0012] While employing a thermal imidization method can suppress gel defects, it requires an imidization reaction at a higher temperature, which can easily lead to discoloration problems. Furthermore, it tends to increase the peel strength when removing the polymer precursor film from the support, making peeling difficult.

[0013] Therefore, the object of the present invention is to provide a method for producing a polymer film that can suppress deterioration of physical properties and appearance due to gel defects while also reducing problems such as discoloration and increased peel strength of the polymer film. Furthermore, the object of the present invention is to provide a method for producing polymers that can be used in such a polymer film production method.

[0014] On the one hand, the problem of difficulty in long-term continuous production in the invention of Patent Document 1 is not limited to the case of manufacturing a polyimide film, but also occurs in the case of manufacturing a laminate having a resin layer containing polyimide on a support.

[0015] Further, when heating the polyamic acid solution on the support, since heating is performed by an oven in a state where one side is blocked by the support, the surface on the support side is difficult to be heated, and the heating state is different between the air interface side and the support side of the polyimide. Due to this, in a subsequent process involving high-temperature heating (for example, 150 to 500 ° C), it was found that the laminate warps together with the support. Such a tendency was observed not only in the case of the thermal imidization method but also in the case of the chemical imidization method.

[0016] Furthermore, in a support on which a flexible substrate layer made of such a high heat-resistant resin layer is laminated, since the support (for example, an inorganic substrate such as glass) is used as a carrier for substrate After forming an electronic element on the surface of the high heat-resistant resin layer, it is necessary to finally peel and separate the high heat-resistant resin layer from the support. However, in the polyimide resin layer where the heating states of the front and back are different, there is also a problem that the polyimide resin layer with an electronic element warps after peeling from the support. In addition, when peeling the high heat-resistant resin layer from the support, depending on the peeling strength, laser peeling may be required, and it was also found that warping is likely to occur in the high heat-resistant resin layer after peeling due to the temperature rise during such laser irradiation.

[0017] Therefore, another object of the present invention is to provide a method for manufacturing a laminate that can reduce warping of the laminate and warping of the resin layer after peeling while suppressing gel defects, and a method for manufacturing a flexible substrate using the same. Another object is to provide a method for generating a polymer that can be used in such a method for manufacturing a polymer film. Further, an object of the present invention is to provide a method for generating a polymer that can be used in such a method for manufacturing a laminate.

Means for Solving the Problems

[0018] As a result of diligent research to solve the above problems, the present inventors have discovered that by pre-placing a reaction accelerator for promoting the chemical reaction of polymer precursors on the surface of the support, contrary to expectations, the reaction accelerator diffuses suitably, obtaining a sufficient reaction-promoting effect. This allows for sufficient suppression of gel defects and also reduces the peel strength from the support, thus completing the present invention.

[0019] Furthermore, the inventors have discovered that by means similar to those described above, gel defects can be sufficiently suppressed, and warping of the laminate and the resin layer after delamination can be reduced, thus completing the present invention.

[0020] In other words, the present invention includes the following:

[0021] [1] A method for producing a polymer, comprising the steps of coating a support with a solution containing a polymer precursor and chemically reacting the polymer precursor, A method for producing a polymer, comprising pre-presenting a reaction accelerator for promoting the chemical reaction of the polymer precursor on the surface of the support.

[0022] [2] A method for producing a polymer film, comprising the step of forming a polymer film on a support by the polymer production method described in [1].

[0023] [3] A method for producing a polymer film according to [2], comprising the steps of heating the applied solution to obtain a self-supporting polymer precursor film, and peeling the polymer precursor film from the support.

[0024] [4] The method for producing a polymer film according to [3], wherein the peel strength between the support and the polymer precursor film is 0.001 N / cm or more and 0.9 N / cm or less.

[0025] [5] The polymer film is a polyimide resin film, and the amount of the reaction accelerator present per unit area is 5 to 150 mg / m² per 1 μm of thickness of the polyimide resin film.2 The method for producing a polymer film as described in any of [2] to [4].

[0026] [6] A method for producing a polymer film according to any one of [2] to [5], wherein the polymer film is a polyimide film and the solution of the polymer precursor is a polyamic acid solution.

[0027] [7] The method for producing a polymer film according to [5] or [6], wherein the reaction accelerator is an imidation accelerator.

[0028] [8] A method for producing a polymer film according to any one of [2] to [7], wherein the polymer film is a transparent polyimide film.

[0029] A method for producing a laminate, comprising the step of obtaining a laminate having a resin layer containing a polymer on the support by the polymer production method described in [1] [9] [1].

[0030]

[10] The method for producing a laminate according to [9], wherein the chemical reaction is carried out under heating, and the amount of warping of the obtained laminate when heated at 300°C for 1 hour is 300 μm or less.

[0031]

[11] The method for manufacturing a laminate according to [9] or

[10] , wherein the laminate has a curvature of 1000 μm or less of the resin layer peeled off from the support.

[0032]

[12] The resin layer contains a polyimide resin, and the amount of the reaction accelerator present per unit area is 5 to 150 mg / m² per 1 μm of the thickness of the resin layer. 2 A method for manufacturing a laminate as described in any of [9] to

[11] .

[0033]

[13] A method for producing a laminate according to any one of [9] to

[12] , wherein the polymer is a polyimide and the solution of the polymer precursor is a polyamic acid solution.

[0034]

[14] The method for producing a laminate according to

[12] or

[13] , wherein the reaction accelerator is an imidization accelerator.

[0035]

[15] A functional layer formation step in which a functional layer is formed on the resin layer of the laminate obtained by the manufacturing method described in any of [9] to

[14] , A separation step of peeling the resin layer from the support to obtain a flexible substrate having the functional layer on the resin layer, A method for manufacturing a flexible substrate, including the method described above. [Effects of the Invention]

[0036] According to the present invention, it is possible to provide a method for manufacturing a polymer film that suppresses deterioration of physical properties and appearance due to gel defects, while also reducing problems such as discoloration of the polymer film and increased peel strength. In particular, in the examples shown, it is possible to suppress the decrease in tensile modulus, elongation, and breaking strength due to gel defects, as well as color unevenness, and furthermore, to suppress the increase in the yellow index (YI) and the increase in the peel strength of the support.

[0037] Furthermore, according to the present invention, it is possible to provide a method for manufacturing a laminate that can suppress gel defects while reducing warping of the laminate and warping of the resin layer after delamination, as well as a method for manufacturing a flexible substrate using the same. [Brief explanation of the drawing]

[0038] [Figure 1] The following are schematic diagrams illustrating the method for measuring the warpage of a laminate of a resin layer and a support in the examples, where (a) is a plan view and (b) is a cross-sectional view taken along the (b)-(b) line in (a). [Modes for carrying out the invention]

[0039] The present invention will be described in detail below. For convenience of explanation, the film formation direction may be referred to as the machine axis direction, longitudinal direction, longitudinal direction, or MD direction, and the direction perpendicular to the film formation direction and the thickness direction may be referred to as the width direction, transverse direction, or TD direction. Furthermore, the various physical properties described herein are specifically measured by the methods described in the examples.

[0040] [Methods for producing polymers] A method for producing a polymer according to one embodiment of the present invention is a method for producing a polymer comprising the steps of coating a solution containing a polymer precursor onto a support and chemically reacting the polymer precursor, characterized in that a reaction accelerator for promoting the chemical reaction of the polymer precursor is present on the surface of the support in advance.

[0041] This polymer production method has two aspects: one is for use in the manufacturing of polymer films, and the other is for use in the manufacturing of laminates.

[0042] In other words, a method for manufacturing a polymer film according to one embodiment of the present invention is a method for manufacturing a polymer film that includes the step of forming a polymer film on the support by the polymer production method described above. Furthermore, a method for manufacturing a laminate according to one embodiment of the present invention is a method for manufacturing a laminate that includes the step of obtaining a laminate having a resin layer containing a polymer on the support by the polymer production method described above.

[0043] The following describes, in order, a method for manufacturing a polymer film and a method for manufacturing a laminate, which are embodiments of one invention.

[0044] [Method for manufacturing polymer films] A method for producing a polymer film according to one embodiment of the present invention includes the steps of coating a solution containing a polymer precursor onto a support and chemically reacting the polymer precursor. In this method, a reaction accelerator for promoting the chemical reaction of the polymer precursor is provided in advance on the surface of the support.

[0045] The exact reason for the effect of pre-presenting the reaction accelerator on the support surface is unclear, but it can be tentatively inferred as follows. In other words, since gel defects were reduced in the examples compared to when the reaction accelerator was added to the solution, it is thought that pre-presenting the reaction accelerator on the support surface suppressed localized gelation. Furthermore, it has been shown that reducing gel defects suppresses deterioration of physical properties and appearance due to gel defects. Moreover, since mechanical properties equivalent to or better than those obtained in the case of thermal imidation were obtained, it is thought that the concentration gradient when the reaction accelerator diffuses into the solution containing the polymer precursor and the temperature gradient due to heating were well balanced, and the chemical reaction was promoted without bias. In addition, the fact that the peel strength between the support and the polymer precursor film did not increase, but rather decreased, compared to when the reaction accelerator was added to the solution, in the examples is a particularly unexpected effect and is thought to be a result of the above balance.Therefore, it is inferred that similar effects will occur not only with the polyimide film used in the examples, but also with polymer films such as those described below.

[0046] Furthermore, the present invention preferably includes the steps of heating the coated solution to obtain a self-supporting polymer precursor film, and peeling the polymer precursor film from the support. In this case, compared to peeling after the chemical reaction of the polymer precursor, peeling from the support becomes easier, increasing the degree of freedom in subsequent processing, and also providing the effect of uniform heating from both sides in the subsequent heating step.

[0047] In addition, in this invention, instead of the step of peeling the polymer precursor film from the support, it is also possible to peel off the polymer film obtained by chemically reacting the polymer precursor from the support.

[0048] <Polymer film> The polymer constituting the resin layer is not particularly limited as long as it is obtained by chemically reacting a polymer precursor in the presence of a reaction accelerator, but examples include heat-resistant resins such as polyimides, polyamideimides, polyetherimides, and aromatic polyamides, and reaction-curable resins such as epoxy resins. Among these, polyamideimides, polyimides, and polyetherimides that form imide bonds through imidation reactions are preferred. In the present invention, polymers having such imide bonds are collectively referred to as "polyimide resins."

[0049] When the polymer film is a heat-resistant resin film, the heat-resistant resin is preferably a film with a melting point of 250°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. Furthermore, the film is made of a polymer with a glass transition temperature of 200°C or higher, more preferably 320°C or higher, and even more preferably 380°C or higher. In this specification, the melting point and glass transition temperature are determined by differential thermal analysis (DSC). If the melting point exceeds 500°C, it may be determined whether or not the melting point has been reached by visually observing the thermal deformation behavior when heated at the relevant temperature.

[0050] <Polymer precursor> In the present invention, "polymer precursor" refers to a polymer that constitutes a polymer film that will become a product, in a state before the chemical reaction is completed, and includes, for example, states in which the chemical structure, crosslinking reaction, or high molecular weight formation is not yet complete.

[0051] For example, polyimide films and polyamide-imide films are generally made by mixing diamines with trivalent or tetravalent diamines in a solvent. Carboxylic acids The polyamic acid solution obtained by reacting with is applied to a support and dried to form a polyamic acid film containing, for example, 1 to 50% by mass of solvent. Furthermore, the polyamic acid film containing 1 to 50% by mass of solvent is subjected to a high-temperature treatment on or off the support to carry out an imidization reaction. For this reason, the polyamic acid corresponds to the polymer precursor.

[0052] Generally, polyamide films are obtained by coating a polyamide solution, obtained by reacting diamines and dicarboxylic acids in a solvent, onto a support, drying it to form a polyamide film containing, for example, 1 to 50% by mass of solvent, and then subjecting the polyamide film containing 1 to 50% by mass of solvent to high-temperature treatment on or off the support to increase its molecular weight. For this reason, polyamide that has not yet undergone high molecular weight conversion corresponds to a polymer precursor.

[0053] Furthermore, reaction-curable resin films are obtained by applying epoxy resin or the like to a support along with a curing agent, drying it to form a B-stage film, and then subjecting the film to a high-temperature treatment on or after peeling it off the support to induce a crosslinking reaction. For this reason, epoxy resin or the like in which the crosslinking reaction (or curing reaction) has not yet been completed corresponds to a polymer precursor.

[0054] The solvents used in these reaction systems, as well as reaction accelerators such as imidation accelerators, dehydrating agents, catalysts, co-catalysts, curing agents, and curing accelerators, can be those that are well known and can be used depending on the reaction system.

[0055] The following provides a detailed explanation of an example of manufacturing a polyimide resin film using polyamic acid as a polymer precursor.

[0056] <Polyimide resin film> Generally, polyimide films are obtained by coating a polyamic acid (polyimide precursor) solution, which is obtained by reacting diamines and tetracarboxylic acids in a solvent, onto a support and drying it to form a green film (hereinafter also referred to as "precursor film" or "polyamic acid film"). Furthermore, the green film is subjected to high-temperature heat treatment on or after being peeled from the support to carry out a dehydration and ring-closing reaction (imidation reaction) (thermal imidation method).

[0057] In conventional chemical imidation methods, an imidation accelerator is added to the polyamic acid solution to accelerate the imidation reaction, allowing the imidation reaction to be carried out by heat treatment at a lower temperature. In this invention, instead of adding the imidation accelerator to the polyamic acid solution, it is pre-present on the surface of the support.

[0058] Here, "green film" refers to a polyamic acid film containing a solvent and having self-supporting properties. The solvent content of the green film is not particularly limited as long as it has self-supporting properties, but it is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. It is also preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0059] The application of the polyamic acid (polyimide precursor) solution can be carried out using conventionally known application methods such as spin coating, doctor blade, applicator, comma coater, screen printing, slit coating, reverse coating, dip coating, curtain coating, and slit die coating. While the method of creating a film by applying a polyamic acid solution offers a wide range of material choices, making it easier to find a material suitable for easy peeling, controlling the imidation reaction becomes crucial. In contrast, film formation without an imidation reaction has the advantage of being easier, allowing for appropriate use depending on the application.

[0060] When heating a coated polyamic acid solution to obtain a self-supporting polymer precursor film, the heating temperature is preferably 70 to 130°C, and more preferably 80 to 125°C. A temperature above the lower limit allows for efficient removal of the solvent, while a temperature below the upper limit makes it easier to prevent the peel strength between the support and the polymer precursor film from increasing too much.

[0061] The polyimide resin film in the present invention is a polymer film having imide bonds in its main chain, preferably a polyimide film or a polyamideimide film, and more preferably a polyimide film.

[0062] Generally, polyimide films are obtained by the method described above. Alternatively, they can be obtained by coating a polyimide solution, obtained by a dehydration and cyclization reaction between diamines and tetracarboxylic acids in a solvent, onto a support and drying it to form a polyimide film containing, for example, 1 to 50% by mass of solvent. The polyimide film containing 1 to 50% by mass of solvent can then be subjected to high-temperature treatment and dried, either on the support or peeled off from the support. In this case, the polyimide whose high molecular weight has not yet been completed corresponds to the polymer precursor.

[0063] There are no particular restrictions on the diamines that constitute the polyamic acid; aromatic diamines, aliphatic diamines, alicyclic diamines, etc., commonly used in polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred.

[0064] There are no particular limitations on aromatic diamines; for example, oxydianiline (bis(4-aminophenyl) ether), Examples include paraphenylenediamine (1,4-phenylenediamine). Diamines may be used individually or in combination of two or more.

[0065] As tetracarboxylic acids constituting polyamic acids, aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids (including their acid anhydrides), which are commonly used in polyimide synthesis, can be used. When these are acid anhydrides, there may be one or two anhydride structures in the molecule, but those having two anhydride structures (dianhydrides) are preferred. Only one type of tetracarboxylic acid may be used, or two or more types may be used in combination.

[0066] Furthermore, in order to introduce amide bonds into part of the main chain of polyimide resins, tetracarboxylic acids are used instead of or in part with amide bonds. Tricarboxylic acids It is also possible to use dicarboxylic acids in place of some of the tetracarboxylic acids to copolymerize the polyamide components.

[0067] There are no particular limitations on the tetracarboxylic acid, and examples include pyrrolimetic acid dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

[0068] <Transparent polyimide film> Among polyimide resin films, transparent polyimide films are preferred, and will be described in more detail. The transparency of the transparent polyimide is preferably such that the total light transmittance is 75% or higher. More preferably 80% or higher, even more preferably 85% or higher, even more preferably 87% or higher, and particularly preferably 88% or higher. While there is no particular upper limit to the total light transmittance, for use as a flexible electronic device, it is preferably 98% or lower, and more preferably 97% or lower.

[0069] Aromatic tetracarboxylic acids used to obtain a colorless and highly transparent polyimide in the present invention include 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4'-oxydiphthalic acid, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylic acid)1,4-phenylene, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)benzene-1,4-dicarboxylate, and 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzene-1,4-diyl Dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(toluene-2,5-diyloxy)] (4-isopropyltoluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxatiol-1,1-dioxide-3,3-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3H-2,1-benz [(3H-2,1-benzoxatiol-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3H-2,1-benzoxatiol-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxatiol-1,1-dioxide-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,Examples include tetracarboxylic acids such as 4'-(3H-2,1-benzoxatiol-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(xanthene-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]diphthalic acid, and 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]diphthalic acid, as well as their acid anhydrides. Among these, dianhydrides having two acid anhydride structures are preferred, and in particular, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride and 4,4'-oxydiphthalic acid dianhydride are preferred. Note that only one aromatic tetracarboxylic acid may be used, or two or more may be used in combination.

[0070] When heat resistance is important, the copolymerization amount of aromatic tetracarboxylic acids is preferably 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may even be 100% by mass.

[0071] Alicyclic tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3,3',4,4'-bicyclohexyltetracarboxylic acid, bicyclo[2,2,1]heptane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid, and bicyclo[2,2,2]octo-7-ene-2,3,5,6-tetracarboxylic acid. Bonic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, decahydronaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane -5,5'',6,6''-tetracarboxylic acid (also known as "norbornane-2-spiro-2'-cyclopentanone-5'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid"), methylnorbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclohexanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid (also known as "norbornane-2-s Pyrro-2'-cyclohexanone-6'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid), methylnorbornane-2-spiro-α-cyclohexanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclopropanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclobutanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclooctanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclononanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclodecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α'-spiro-2''-norbornane-5,5'' Examples include tetracarboxylic acids such as ,6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotridecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentadecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclopentanone)-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, and their acid anhydrides. Furthermore, examples include double-decker type silsesquioxane derivatives containing acid anhydride groups represented by the structure of formula (1) below. Among these, dianhydrides having two acid anhydride structures are preferred, and in particular, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride, and 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride are preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is even more preferred. Note that one of these may be used alone, or two or more may be used in combination.

[0072] [ka]

[0073] When transparency is important, the copolymerization amount of alicyclic tetracarboxylic acids is preferably 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may even be 100% by mass.

[0074] Examples of tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalene tricarboxylic acid, diphenyl ether-3,3',4'-tricarboxylic acid, and diphenyl sulfone-3,3',4'-tricarboxylic acid, or hydrogenated versions of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid, alkylene glycol bistrimellitates such as ethylene glycol bistrimellitate, propylene glycol bistrimellitate, 1,4-butanediol bistrimellitate, and polyethylene glycol bistrimellitate, and their monoanhydrides and esterified products. Among these, monoanhydrides having one acid anhydride structure are preferred, and trimellitic anhydride and hexahydrotrimellitic anhydride are particularly preferred. Note that one of these may be used alone, or two or more may be used in combination.

[0075] Dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid, or hydrogenated versions of the above aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, heptanediic acid, octanedioic acid, azelaic acid, and sebacic acid. Undecane dioic acidExamples include dodecanediic acid, 2-methylsuccinic acid, and their acid chlorides or esters. Among these, aromatic dicarboxylic acids and their hydrogenated products are preferred, with terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid being particularly preferred. Dicarboxylic acids may be used individually or in combination of two or more.

[0076] The diamines or isocyanates used to obtain the colorless and highly transparent polyimide in the present invention are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc., which are commonly used in polyimide synthesis, polyamide-imide synthesis, and polyamide synthesis, can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. Furthermore, using aromatic diamines having a benzoxazole structure makes it possible to achieve high heat resistance, high modulus of elasticity, low thermal shrinkage, and a low coefficient of linear expansion. Diamines and isocyanates may be used individually or in combination of two or more.

[0077] Examples of aromatic diamines include 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, and bis[4 -(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4-amino-N-(4-aminophenyl)benzamide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2'-trifluoromethyl-4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4, 4'-Diaminobenzophenone, 3,3'-Diaminodiphenylmethane, 3,4'-Diaminodiphenylmethane, 4,4'-Diaminodiphenylmethane, Bis[4-(4-aminophenoxy)phenyl]methane, 1,1-Bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-Bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-Bis[4-(4-aminophenoxy)phenyl]propane, 1,2-Bis[4-(4-aminophenoxy)phenyl]propane, 1,3-Bis[4-(4-aminophenoxy)phenyl]propane, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane, 1,1-Bis[4-(4-aminophenoxy)phenyl]butane, 1,3-Bis[4-(4-aminophenoxy)phenyl]butane, 1,4-Bis[4-(4-aminophenoxy)phenyl]butane, 2,2-Bis[4-(4-aminophenoxy)phenyl]butane, 2,3-Bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3-methylphenyl]propane, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane, 1,1-Bis[4-(4-aminophenoxy)phenyl]butane, 1,3-Bis[4-(4-aminophenoxy)phenyl]butane, 1,4-Bis[4-(4-aminophenoxy)phenyl]butane, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane-2-[4-(4-aminophenoxy)-3-methylphenyl]propane, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane-2-Bis[4-(4-aminophenoxy)-3-methylphenyl]propane [nophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis( 4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4- Bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis[(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-Bis[4-(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4'-Bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-Bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-Bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-Bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, Bis[4-{4-(4-aminophenoxy)pheno [Xy / phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene , 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4, 4'-Dibiphenoxybenzophenone, 4,4'-Diamino-5,5'-Dibiphenoxybenzophenone, 3,4'-Diamino-4,5'-Dibiphenoxybenzophenone, 3,3'-Diamino-4-Biphenoxybenzophenone, 4,4'-Diamino-5-Biphenoxybenzophenone, 3,4'-Diamino-4-Biphenoxybenzophenone, 3,4'-Diamino-5'-Biphenoxybenzophenone, 1,3-Bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-Bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-Bis(4-amino-5-phenoxybenzoyl)benzene, 1,4-Bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-Bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-Bis(3-amino-4-biphenoxybenzoyl)benzene, 1,3-Bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-Bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-Bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, 4,4'-[9H-fluorene-9,9-diyl]bisaniline (also known as "9,9-bis(4-aminophenyl) Examples include fluorene, spiro(xanthene-9,9'-fluorene)-2,6-diyrbis(oxycarbonyl)bisaniline, 4,4'-[spiro(xanthene-9,9'-fluorene)-2,6-diyrbis(oxycarbonyl)bisaniline, 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diyrbis(oxycarbonyl)bisaniline, 9,10-bis(4-aminophenyl)adenine, 2,4-bis(4-aminophenyl)cyclobutane-1,3-dicarboxylate dimethyl, and amino group-containing double-decker type silsesquioxane derivatives represented by the structure of formula (2) below. Furthermore, some or all of the hydrogen atoms on the aromatic ring of the above aromatic diamine may be substituted with halogen atoms, C1-C3 alkyl or alkoxyl groups, or cyano groups, and some or all of the hydrogen atoms of the C1-C3 alkyl or alkoxyl groups may be substituted with halogen atoms.

[0078] [ka]

[0079] Furthermore, there are no particular limitations on the aromatic diamines having the benzoxazole structure, and examples include 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzoxazole), 2,2'-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazolo)benzene, 2,6-(4,4'- Examples include diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, and 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole. Among these, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenylsulfone, and 3,3'-diaminobenzophenone are particularly preferred. Note that only one aromatic diamine may be used, or two or more may be used in combination.

[0080] Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, and 4,4'-methylenebis(2,6-dimethylcyclohexylamine). Among these, 1,4-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. Note that only one type of alicyclic diamine may be used, or two or more may be used in combination.

[0081] Examples of diisocyanates include diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, and 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyl Diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4' -Diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, torylene-2,4-diisocyanate, torylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2-bis(4-phenoxyphenyl)propane) diisocyanate, 3,3'-or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'-or 2,2'-di Examples include aromatic diisocyanates such as ethyl biphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, as well as diisocyanates obtained by hydrogenating any of these (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate).Among these, diphenylmethane-4,4'-diisocyanate, torylene-2,4-diisocyanate, torylene-2,6-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred in terms of low hygroscopicity, dimensional stability, cost, and polymerizability. Diisocyanates may be used individually or in combination of two or more.

[0082] <Solution containing polyamic acid> From the viewpoint of avoiding complexity in the manufacturing process, it is preferable that the solution containing the polyamic acid contains the solvent used during synthesis. While any solvent capable of dissolving polyamic acid can be used as a preferred solvent for synthesizing polyamic acid, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred, with N,N-dimethylformamide and N,N-dimethylacetamide being particularly preferred. Regarding the concentration of the polyamic acid solution during synthesis, a lower concentration is preferable because it allows for a larger amount of solvent in the solution, improving miscibility with the imidization accelerator. However, if the concentration is too low, it becomes difficult to produce a thicker film. The concentration of the polyamic acid solution is preferably 5-30% by mass, and more preferably 10-20% by mass.

[0083] To ensure handling and productivity, it is preferable to add and incorporate approximately 0.03 to 3% by mass of lubricant (particles) with a particle size of about 5 to 1000 nm into the polymer film, thereby creating fine irregularities on the polymer film surface and ensuring slipperiness. For this reason, it is also possible to incorporate the lubricant (particles) into a solution containing the polymer precursor, and inorganic fine particles are a preferred lubricant.

[0084] Examples of inorganic fine particles include particulate silicon dioxide (silica) powder, inorganic oxide powders such as aluminum oxide powder, and inorganic salt powders such as particulate calcium carbonate powder and calcium phosphate powder. Since coarse particles of these inorganic fine particles may cause defects in subsequent processes, it is preferable that these inorganic fine particles be uniformly dispersed.

[0085] Furthermore, the polymer precursor solution may contain known additives used in polyimide resin films, to the extent that it does not impair the effects of the present invention. It is also possible to include a portion of the imidation accelerator used in the polymer precursor solution. In order to obtain the effects of the present invention, it is preferable that the proportion of such imidation accelerator be as low as possible, and it is preferable to coat the support with 70% by mass or more of the imidation accelerator. More preferably, it is 90% by mass or more, and most preferably 100% by mass.

[0086] <Imidification promoter> In the present invention, it is preferable to use a tertiary amine as the imidation accelerator to be pre-presented on the support. Heterocyclic tertiary amines are even more preferable. Preferred specific examples of heterocyclic tertiary amines include pyridine, 2,5-diethylpyridine, picoline, quinoline, and isoquinoline.

[0087] In the present invention, the imidation accelerator is pre-presented on the surface of the support to which the polymer precursor solution is to be applied. Specifically, the imidation accelerator can be pre-presented on the surface of the support by methods such as coating, transfer, lamination, compression, and adhesion, but the coating method is preferred. The method of applying the imidation accelerator to the support is not particularly limited; in addition to directly applying the solution to the support, it is also possible to apply it by coating it with another transfer material and then transferring it to the support. In the present invention, from the viewpoint of uniformly applying the imidation accelerator to the surface of the support, spray coating, wire coating, and bar coating are preferred. Law, spirit Phase deposition methods are preferred.

[0088] If the imidization accelerator is a solid, it is preferable to dissolve it in a solvent and perform the coating using the method described above. Although complete drying may be performed after coating, it is also possible to apply the polymer precursor solution while it contains a certain amount of solvent.

[0089] The solvent used during coating is not particularly limited as long as it dissolves the imidization accelerator, but since a polyamic acid solution will be applied in a later step, it is preferable that the solvent used is the same as that for the polyamic acid solution from the standpoint of compatibility.

[0090] Furthermore, if the imidization accelerator is a liquid, it is possible to coat it as is, but from the viewpoint of easy uniform application and diffusion into the polyamic acid solution, it is preferable to dissolve it in a solvent and coat it using the method described above.

[0091] The preferred range for the amount of imidation accelerator (reaction accelerator) to be present on the surface of the support beforehand (amount present per unit area, hereinafter referred to as "amount present") varies depending on the thickness of the resulting polyimide resin film. Therefore, there is a preferred range for the amount per 1 μm of polyimide resin film thickness. In other words, the amount of imidation accelerator present is 5 to 150 mg / m² per 1 μm of polyimide resin film thickness. 2 Preferably, 7-100 mg / m² 2 This is more preferable. The amount of imidization accelerator present is 5 mg / m² per 1 μm of thickness of the polyimide resin film. 2 The above is preferable because it facilitates a sufficient imidation reaction by the imidation accelerator. Also, 150 mg / m² is preferable. 2 The following conditions tend to result in a lower proportion of imidization accelerators that do not participate in the reaction, which is therefore preferable from a cost perspective.

[0092] Such quantities can be adjusted by, for example, the coating thickness, the concentration of the coating solution, or a combination thereof, but adjusting by the concentration of the coating solution is preferable because it allows for independent control of the coating thickness. The coating thickness of the coating solution is preferably 10 to 500 μm, and more preferably 30 to 250 μm. In the case of such coating thicknesses, the concentration of the coating solution is preferably 0.01% by mass or more and 10% by mass or less. After coating with the imidization accelerator and before coating with the polyamic acid solution, the amount of solvent may be appropriately reduced by heating or other means.

[0093] When a polyamic acid solution is applied to a support coated with an imidation accelerator solution, the imidation accelerator on the support dissolves and diffuses into the solvent contained in the polyamic acid solution.

[0094] In the present invention, when the polyimide is a transparent polyimide, the heating temperature required for imidization is lowered by adding an imidization accelerator, thereby suppressing discoloration (increase in yellowness) of the polyimide.

[0095] <Support> The material of the support in this invention is not particularly limited as long as it does not chemically react with the imidization accelerator, but suitable materials include inorganic supports such as metals and polymer supports such as polyethylene terephthalate. When a polymer support is used, at least the surface of the support coated with the imidization accelerator may be coated with a coating such as an easy-peel coating or a hydrophilic coating.

[0096] In this invention, the shape of the support is not particularly limited. It may be a long support such as a polymer film, a shorter sheet-like support, or a molded body having a three-dimensional structure.

[0097] In the present invention, the surface roughness Ra of the support surface coated with the imidation accelerator is preferably 10 nm or less, more preferably 7 nm or less, and more preferably 5 nm or less. In the manufacturing method of the present invention, the irregularities on the surface of the support are transferred to the polyimide surface, so by using a support with a surface roughness of 10 nm or less, a polyimide film with a smooth surface can be obtained.

[0098] In this invention, it is preferable to peel the polymer precursor film from the support before carrying out the imidation reaction. At this time, it is preferable that the peel strength between the support and the polymer precursor film is 0.001 N / cm or more and 0.9 N / cm or less, and more preferably 0.01 N / cm or more and 0.5 N / cm or less. If the peel strength is 0.001 N / cm or more, sufficient transportability can be ensured in the transport process until the polymer precursor film is peeled off. Furthermore, if the peel strength is 0.9 N / cm or less, it becomes less likely that the film or support will break when peeling off the polymer precursor film.

[0099] <Process of chemically reacting polymer precursors> In the process of chemically reacting polymer precursors, conditions are applied according to the type of polymer film. For example, in the case of polyimide resin films, the conditions are as follows.

[0100] While the heat treatment for the imidation reaction can be carried out at a constant temperature, it is preferable to increase the temperature continuously or stepwise to avoid rapid film shrinkage and suppress problems such as breakage and deterioration of surface smoothness due to rapid solvent evaporation.

[0101] When heat treatment is performed while increasing the temperature, the minimum temperature is preferably 150 to 190°C, and the maximum temperature is preferably 280 to 450°C. More preferably, the minimum temperature is 180 to 190°C, and more preferably, the maximum temperature is 290 to 450°C. When performed at a constant temperature, the temperature is preferably 200 to 370°C, and more preferably 210 to 350°C.

[0102] The total time for the heat treatment is preferably 5 to 60 minutes, and more preferably 10 to 50 minutes.

[0103] Although heat treatment can be performed without fixing the edges of the film, it is preferable to fix the edges of the film to ensure uniformity of film thickness, flatness, and suppression of sagging.

[0104] For securing the edges, tenters such as pin tenters, various frames, etc., can be used. Furthermore, as described later, it is also possible to stretch the film using tenters, etc., or to perform heat fixing or heat relaxation after stretching.

[0105] The resulting polyimide resin film can be trimmed using a slitter to remove any parts with poor flatness. Furthermore, in the case of long lengths, the film can be wound into rolls to form rolls of polyimide resin film, or cut into individual sheets.

[0106] <Properties of polymer films> The polymer film, which is one embodiment of the present invention, may have a single-layer structure or a multi-layer (laminated) structure of two or more layers. When the polymer film has a single-layer structure, the physical properties of the polymer film (tensile modulus, melting point, glass transition temperature, yellowness index, total light transmittance, haze, CTE, etc.) refer to the values ​​for the entire polymer film.

[0107] If the polymer film is a transparent polymer film, its yellowness index (hereinafter also referred to as "yellow index" or "YI") is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 3 or less. The lower limit of the yellowness index of the transparent polymer film is not particularly limited, but for use as a flexible electronic device, it is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.

[0108] The light transmittance of the transparent polymer film at a wavelength of 400 nm in the present invention is preferably 70% or more, more preferably 72% or more, even more preferably 75% or more, and even more preferably 80% or more. There is no particular upper limit to the light transmittance of the transparent polymer film at a wavelength of 400 nm, but for use as a flexible electronic device, it is preferably 99% or less, more preferably 98% or less, and even more preferably 97% or less.

[0109] The haze of the transparent polymer film in the present invention is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and even more preferably 0.3 or less. The lower limit is not particularly limited, but industrially, a value of 0.01 or more is acceptable, and a value of 0.05 or more is also acceptable.

[0110] The average coefficient of linear expansion (CTE) of the polymer film between 30°C and 250°C is preferably 50 ppm / K or less. More preferably 45 ppm / K or less, even more preferably 40 ppm / K or less, even more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less. It is also preferably -5 ppm / K or more, more preferably -3 ppm / K or more, and even more preferably 1 ppm / K or more. When the CTE is within the above range, the difference in the coefficient of linear expansion with a general support (inorganic substrate) can be kept small, and peeling of the polymer film from the inorganic substrate or warping of the support can be avoided even when subjected to a heat-applying process. Here, CTE is a factor that represents reversible expansion and contraction with respect to temperature. Note that the CTE of the polymer film refers to the average value of the CTE in the flow direction (MD direction) and the CTE in the width direction (TD direction) of the polymer film.

[0111] Furthermore, polyimide films exhibiting the above coefficient of linear expansion (CTE) can also be achieved by stretching during the film formation process of the polyimide film. This stretching operation can be achieved by applying a polyimide solution to a support for polyimide film production, drying it to form a polyimide film containing 1 to 50% by mass of solvent, and then drying the polyimide film containing 1 to 50% by mass of solvent either on the support or peeled off the support by high-temperature treatment, stretching it 1.5 to 4.0 times in the MD direction and 1.4 to 3.0 times in the TD direction. In this process, an unstretched thermoplastic polymer film is used as the support for polyimide film production, and the thermoplastic polymer film and polyimide film are stretched simultaneously before peeling the stretched polyimide film from the thermoplastic polymer film. This prevents damage to the polyimide film, especially during stretching in the MD direction, and allows for the production of a higher-quality polyimide film.

[0112] The thickness of the polymer film in this invention is preferably 5 μm or more, more preferably 8 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. There is no particular upper limit to the thickness of the polymer film, but for use as a flexible electronic device, it is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 90 μm or less. If it is too thin, film manufacturing and transport become difficult, and if it is too thick, roll transport becomes difficult.

[0113] The tensile modulus of the polymer film is preferably 1 GPa or more, more preferably 2 GPa or more, and even more preferably 3 GPa or more. There is no particular upper limit to the tensile modulus, but it is about 15 GPa. If the tensile modulus is 15 GPa or less, the polymer film can be used as a flexible film. If the tensile modulus is 4 GPa or more, excessive elongation is less likely to occur during handling. The method for measuring the tensile modulus of the polymer film is as described in the examples.

[0114] The thickness unevenness of the polymer film is preferably 20% or less, more preferably 12% or less, still more preferably 7% or less, and particularly preferably 4% or less. When the thickness unevenness exceeds 20%, it tends to be difficult to apply to the narrow part. The thickness unevenness of the polymer film can be obtained, for example, by randomly extracting about 10 positions from the film to be measured with a contact type film thickness gauge, measuring the film thickness, and calculating based on the following formula.

[0115] Film thickness unevenness (%) = 100×(maximum film thickness - minimum film thickness)÷average film thickness

[0116] The number of gel defects per unit area of the polymer film is 0 to 3.0 pieces / 1000 m 2 is preferable, 0 to 2.0 pieces / 1000 m 2 is more preferable, 0 to 1.5 pieces / 1000 m 2 is still more preferable. When the number of gel defects per unit area is 3.0 pieces / 1000 m or less, the deterioration of physical properties and appearance due to gel defects can be more effectively suppressed. 2

[0117] The polymer film is preferably obtained in a form wound as a long polymer film having a width of 300 mm or more and a length of 10 m or more during its production, and more preferably in the form of a roll-shaped polymer film wound around a winding core. When the polymer film is wound in a roll shape, transportation in the form of the roll-shaped polymer film becomes easy.

[0118] [Method for manufacturing a laminate] The method for manufacturing a laminate according to an embodiment of the present invention includes a step of applying a solution containing a polymer precursor onto a support, and a step of obtaining a laminate having a resin layer containing a polymer on the support by chemically reacting the polymer precursor. At that time, it is characterized in that a reaction accelerator for promoting the chemical reaction of the polymer precursor is previously present on the surface of the support.

[0119] The exact reason for the effect of pre-adding the reaction accelerator to the surface of the support is unclear, but it is tentatively speculated as follows. In other words, since gel defects were reduced in the examples compared to when the reaction accelerator was added to the solution, it is thought that pre-adding the reaction accelerator to the surface of the support suppressed localized gelation. Furthermore, although one side of the solution containing the coated polymer precursor is blocked by the support, and the way heat is applied differs between the support side and the air interface side, making it easy for the chemical reaction to proceed differently on both sides, it is thought that the degree of reaction is balanced between the support side, where heat is not easily transferred, and the air interface side, thereby effectively reducing the warping of the resulting laminate and resin layer after heating. Therefore, it is inferred that similar effects will occur not only for the polyimide resin layer used in the examples, but also for the resin layers described below.

[0120] <Resin layer> The polymer constituting the resin layer is not particularly limited as long as it is obtained by chemically reacting a polymer precursor in the presence of a reaction accelerator, but examples include heat-resistant resins such as polyimides, polyamideimides, polyetherimides, and aromatic polyamides, and reaction-curable resins such as epoxy resins. Among these, polyamideimides, polyimides, and polyetherimides that form imide bonds through imidation reactions are preferred. In the present invention, polymers having such imide bonds are collectively referred to as "polyimide resins."

[0121] When the polymer contained in the resin layer is a heat-resistant resin, the heat-resistant resin preferably has a melting point of 250°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. Furthermore, the polymer preferably has a glass transition temperature of 200°C or higher, more preferably 320°C or higher, and even more preferably 380°C or higher. In this specification, the melting point and glass transition temperature are determined by differential thermal analysis (DSC). If the melting point exceeds 500°C, it may be determined whether or not the melting point has been reached by visually observing the thermal deformation behavior when heated at the relevant temperature.

[0122] <Polymer precursor> In the present invention, "polymer precursor" refers to a polymer constituting the resin layer in a state before the chemical reaction is completed, and includes, for example, a state in which the chemical structure, crosslinking reaction, or high molecular weight formation is not yet complete.

[0123] For example, polyimide resin layers and polyamide-imide resin layers are generally composed of diamines and trivalent or tetravalent diamines in a solvent. Carboxylic acids The polyamic acid solution obtained by reacting with is applied to a support and dried to form a polyamic acid precursor layer containing, for example, 1 to 50% by mass of solvent. Furthermore, the polyamic acid precursor layer containing 1 to 50% by mass of solvent is subjected to a high-temperature treatment on the support to carry out an imidation reaction. For this reason, the polyamic acid corresponds to the polymer precursor.

[0124] Generally, a polyamide resin layer is obtained by coating a support with a polyamide solution obtained by reacting diamines and dicarboxylic acids in a solvent, drying it to form a polyamide resin layer (precursor layer) containing, for example, 1 to 50% by mass of solvent, and then treating the polyamide resin layer (precursor layer) containing 1 to 50% by mass of solvent at a high temperature, either on the support or peeled off from the support, to increase its molecular weight. For this reason, polyamide that has not yet undergone high molecular weight conversion corresponds to the polymer precursor.

[0125] Furthermore, the resin layer of a reaction-curable resin is obtained by applying epoxy resin or the like to a support along with a curing agent, drying it to form the B-stage resin layer (precursor layer), and then performing a high-temperature treatment on the support or after peeling it off the support to induce a crosslinking reaction. For this reason, epoxy resin or the like in which the crosslinking reaction (or curing reaction) has not yet been completed corresponds to the polymer precursor.

[0126] The solvents used in these reaction systems, as well as reaction accelerators such as imidation accelerators, dehydrating agents, catalysts, co-catalysts, curing agents, and curing accelerators, can be those that are well known and can be used depending on the reaction system.

[0127] The following describes in detail an example of forming a resin layer of a polyimide-based resin using polyamic acid as a polymer precursor.

[0128] <Polyimide resin layer> Generally, polyimide resin layers are obtained by coating a support with a polyamic acid (polyimide precursor) solution, which is produced by reacting diamines and tetracarboxylic acids in a solvent, and drying it to form a precursor layer. This precursor layer is then subjected to high-temperature heat treatment on the support to carry out a dehydration and ring-closing reaction (imidation reaction) (thermal imidation method).

[0129] In conventional chemical imidation methods, an imidation accelerator is added to the polyamic acid solution to accelerate the imidation reaction, allowing the imidation reaction to be carried out by heat treatment at a lower temperature. In this invention, instead of adding the imidation accelerator to the polyamic acid solution, it is pre-present on the surface of the support.

[0130] In the present invention, it is preferable to first form a precursor layer by coating a support containing a reaction accelerator with a solution containing a polymer precursor and drying it, and then chemically reacting the polymer precursor contained in the precursor layer to obtain a laminate. Here, the precursor layer is a resin layer of polyamic acid that contains a solvent and has self-supporting properties. The solvent content of the precursor layer is not particularly limited as long as it has self-supporting properties, but it is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. It is also preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0131] The application of the polyamic acid (polyimide precursor) solution can be carried out using conventionally known application methods such as spin coating, doctor blade, applicator, comma coater, screen printing, slit coating, reverse coating, dip coating, curtain coating, and slit die coating. While the method of forming a precursor layer by applying a polyamic acid solution offers a wide range of material selection, making it easier to find a material suitable for easy peeling, controlling the imidation reaction becomes crucial. In contrast, film formation without an imidation reaction has the advantage of being easier, allowing for appropriate use depending on the application.

[0132] When heating a coated polyamic acid solution to obtain a self-supporting precursor layer, the heating temperature is preferably 70 to 130°C, and more preferably 80 to 125°C. A temperature above the lower limit allows for efficient removal of the solvent, while a temperature below the upper limit makes it easier to avoid problems caused by rapid shrinkage of the precursor layer.

[0133] The polyimide resin in the present invention is a polymer having imide bonds in its main chain, preferably polyimide or polyamideimide, and more preferably polyimide.

[0134] Generally, polyimide resin layers are obtained by the method described above. Alternatively, a polyimide solution obtained by a dehydration and cyclization reaction between diamines and tetracarboxylic acids in a solvent can be applied to a support and dried to form a polyimide resin layer (precursor layer) containing, for example, 1 to 50% by mass of solvent. This polyimide resin layer containing 1 to 50% by mass of solvent can then be subjected to high-temperature treatment and dried on or after being peeled from the support. In this case, the polyimide that has not yet undergone high molecular weight conversion corresponds to the polymer precursor.

[0135] Regarding the diamines that constitute polyamic acid, the methods described for "methods for manufacturing polymer films" can be applied directly even when forming a resin layer in "methods for manufacturing laminates."

[0136] Regarding the tetracarboxylic acids that constitute polyamic acids, the methods described for "methods for manufacturing polymer films" can be applied directly even when forming a resin layer in the "method for manufacturing laminates."

[0137] <Transparent polyimide resin layer> Among the resin layers of polyimide-based resins, transparent polyimide resin layers are preferably used, and will be described in more detail. The transparency of the transparent polyimide is preferably such that the total light transmittance is 75% or higher. More preferably it is 80% or higher, even more preferably 85% or higher, even more preferably 87% or higher, and particularly preferably 88% or higher. There is no particular upper limit to the total light transmittance, but for use as a flexible electronic device, it is preferably 98% or lower, and more preferably 97% or lower.

[0138] For compounds such as diamines and tetracarboxylic acids used to obtain colorless and highly transparent polyimides, the methods described in the "Method for Manufacturing Polymer Films" can be applied directly to the formation of the resin layer in the "Method for Manufacturing Laminates."

[0139] <Solution containing polyamic acid> For solutions containing polyamic acid, the methods described for "Method for Manufacturing Polymer Films" can be directly applied when forming a resin layer in the "Method for Manufacturing Laminates." In other words, the descriptions of the solvent, the concentration of the polyamic acid solution, the lubricant (particles), and other additives can be directly applied.

[0140] Furthermore, it is possible to include a portion of the imidation accelerator used in the polymer precursor solution. In order to obtain the effects of the present invention, it is preferable that the proportion of such imidation accelerator be as low as possible, and it is preferable to coat the support with 70% by mass or more of the imidation accelerator. More preferably, it is 90% by mass or more, and most preferably 100% by mass.

[0141] <Imidification promoter> In the present invention, it is preferable to use a tertiary amine as the imidation accelerator to be present in the support beforehand. Heterocyclic tertiary amines are even more preferable. Preferred specific examples of heterocyclic tertiary amines include pyridine, 2,5-diethylpyridine, picoline, quinoline, and isoquinoline.

[0142] In the present invention, the imidation accelerator is pre-presented on the surface of the support to which the polymer precursor solution is to be applied. Specifically, the imidation accelerator can be pre-presented on the surface of the support by methods such as coating, transfer, lamination, compression, and adhesion, but the coating method is preferred. The method of applying the imidation accelerator to the support is not particularly limited; in addition to directly applying the solution to the support, it is also possible to apply it by coating it with another transfer material and then transferring it to the support. In the present invention, from the viewpoint of uniformly applying the imidation accelerator to the surface of the support, spray coating, wire coating, and bar coating are preferred. Law, spirit Phase deposition methods are preferred.

[0143] If the imidization accelerator is a solid, it is preferable to dissolve it in a solvent and perform the coating using the method described above. Although complete drying may be performed after coating, it is also possible to apply the polymer precursor solution while it contains a certain amount of solvent.

[0144] The solvent used during coating is not particularly limited as long as it dissolves the imidization accelerator, but since a polyamic acid solution will be applied in a later step, it is preferable that the solvent used is the same as that for the polyamic acid solution from the standpoint of compatibility.

[0145] Furthermore, if the imidization accelerator is a liquid, it is possible to coat it as is, but from the viewpoint of easy uniform application and diffusion into the polyamic acid solution, it is preferable to dissolve it in a solvent and coat it using the method described above.

[0146] The preferred range for the amount of imidation accelerator (reaction accelerator) to be present on the surface of the support beforehand (amount present per unit area, hereinafter referred to as "amount present") varies depending on the thickness of the resin layer of the resulting polyimide resin. Therefore, there is a preferred range for the amount present per 1 μm thickness of the polyimide resin layer. In other words, the amount of imidation accelerator present is 5 to 150 mg / m² per 1 μm thickness of the polyimide resin layer. 2 Preferably, 7-100 mg / m² 2 This is more preferable. The amount of imidization accelerator present is 5 mg / m² per 1 μm thickness of the polyimide resin layer. 2 The above is preferable because it facilitates a sufficient imidation reaction by the imidation accelerator. Also, 150 mg / m² is preferable. 2 The following conditions tend to result in a lower proportion of imidization accelerators that do not participate in the reaction, which is therefore preferable from a cost perspective.

[0147] Such quantities can be adjusted by, for example, the coating thickness, the concentration of the coating solution, or a combination thereof, but adjusting by the concentration of the coating solution is preferable because it allows for independent control of the coating thickness. The coating thickness of the coating solution is preferably 10 to 500 μm, and more preferably 30 to 250 μm. In the case of such coating thicknesses, the concentration of the coating solution is preferably 0.01% by mass or more and 10% by mass or less. After coating with the imidization accelerator and before coating with the polyamic acid solution, the amount of solvent may be appropriately reduced by heating or other means.

[0148] When a polyamic acid solution is applied to a support coated with an imidation accelerator solution, the imidation accelerator on the support dissolves and diffuses into the solvent contained in the polyamic acid solution.

[0149] When forming a resin layer of polyimide resin, an imidization accelerator is applied to the support beforehand, and then a polyamic acid solution is applied and heated on top of it. preferable.In this process, since one side of the resin layer is blocked by the support, if an imidation accelerator is not present, the heat applied to the polyamic acid solution differs between the support side and the air interface side, causing the resulting polyimide resin layer to warp. However, by coating the support with an imidation accelerator, the degree of reaction is balanced between the support side, where heat conduction is poor, and the air interface side, making the resulting polyimide resin layer less prone to warping after heating.

[0150] In the present invention, when the polyimide is a transparent polyimide, the heating temperature required for imidization is lowered by adding an imidization accelerator, thereby suppressing discoloration (increase in yellowness) of the polyimide.

[0151] <Support> The support material is not particularly limited as long as it possesses chemical and mechanical strength that can withstand the thermal history and atmosphere during the manufacturing process in which the resin layer and functional layer are formed. Examples include inorganic materials, metals, and heat-resistant organic resin layers. Specifically, glass, resin films, and metal foils such as copper foil are examples, but a glass substrate is preferably used.

[0152] For example, a glass substrate commonly used in the manufacture of flexible substrates can be used. However, in the flexible substrate manufactured according to this invention, the support base for the functional layer is a resin layer. In other words, the glass substrate referred to here serves as a base when forming the functional layer on the resin layer, and although it may ensure the handling and dimensional stability of the resin layer during the manufacturing process of the flexible substrate, it is ultimately removed and does not constitute the flexible substrate. Furthermore, to prevent the delamination of the resin layer during the processing steps, the support may be subjected to, for example, the addition of functional groups that have an affinity for polyimide, or surface treatment to increase the surface roughness.

[0153] As described above, a glass substrate is preferably used as the support. Examples of glass substrates include soda-lime glass, alkali-free glass, phosphate-based glass, and quartz. Here, since it is possible that a uniform resin layer may not be obtained if the support expands during the heat treatment to cure the resin solution, the thermal expansion coefficient of the support should be 10 ppm / °C or less, preferably 5 ppm / °C or less, and from this viewpoint, alkali-free glass is more preferably used as the glass substrate. The surface of the support may be subjected to chemical surface treatment, such as introducing functional groups that have an affinity for polyimide, such as -OH, -NH, and -Si, to the glass surface, or physical surface treatment, such as forming an uneven surface on the glass surface by etching with a chemical solution, for purposes such as improving adhesion.

[0154] The support material is preferably transparent to laser light. Therefore, it is preferable that the support material has a high transmittance at the wavelength of the laser light used. More specifically, it is preferable that the transmittance at the wavelength of the laser light used is 30% or more. Specifically, in this invention, it is preferable to use a support material with a light transmittance of 30% or more at the wavelength of 308 nm output by an excimer laser. However, other types of lasers besides excimer lasers can also be used in this invention.

[0155] In the present invention, the surface roughness Ra of the support surface coated with the imidation accelerator is preferably 10 nm or less, more preferably 7 nm or less, and more preferably 5 nm or less. In the manufacturing method of the present invention, the irregularities on the surface of the support are transferred to the polyimide surface, so by using a support with a surface roughness of 10 nm or less, a flexible substrate with a smooth surface of the resin layer peeled off from the support can be obtained.

[0156] <Process of chemically reacting polymer precursors> In the process of chemically reacting polymer precursors to obtain a laminate having a polymer-containing resin layer on the support, conditions are applied according to the type of resin layer. For example, in the case of a polyimide resin layer, the conditions are as follows.

[0157] While the heat treatment for the imidation reaction can be carried out at a constant temperature, it is preferable to carry it out while continuously or gradually increasing the temperature, in order to avoid rapid shrinkage of the resin layer and suppress problems such as breakage and deterioration of surface smoothness due to rapid solvent evaporation.

[0158] When performing heat treatment while increasing the temperature, the minimum temperature is preferably 150-190°C, and the maximum temperature is preferably 280-450°C. More preferably, the minimum temperature is 180-190°C, and more preferably, the maximum temperature is 290-450°C. When performing the treatment at a constant temperature, the minimum temperature is preferably 200-370°C, and more preferably 210-350°C. It is also possible to continuously increase the temperature from the drying temperature of the applied solution.

[0159] The total time for heat treatment after drying is preferably 5 to 100 minutes, and more preferably 10 to 50 minutes.

[0160] <Properties of the resin layer> The resin layer in one embodiment of the present invention may be a single layer or a multi-layer (laminated) structure of two or more layers. If the resin layer is a single layer, the physical properties of the resin layer (warpage after heating, tensile modulus, melting point, glass transition temperature, yellowness index, total light transmittance, haze, CTE, etc.) refer to the values ​​for the entire resin layer.

[0161] The amount of warpage of the laminate of the resin layer and support when heated at 300°C for 1 hour is preferably 300 μm or less, and more preferably 250 μm or less. When the warpage of the laminate is 300 μm or less, problems due to warpage tend to be less likely to occur in subsequent processes involving high-temperature heating, such as the process of forming a functional layer. Although there is no specific lower limit, 0 μm is most preferred, and it is substantially 50 μm.

[0162] Furthermore, the amount of warpage of the resin layer peeled off from a laminate heated at 300°C for 1 hour, or the amount of warpage of the resin layer peeled off from an unheated laminate by laser, is preferably 1000 μm or less, and more preferably 800 μm or less. When the amount of warpage of the resin layer peeled off from the support is 1000 μm or less, problems due to warpage are less likely to occur when handling the peeled resin layer, and for example, cracking of the functional layer is less likely to occur. Although there is no particular lower limit, 0 μm is most preferred, and it is substantially 50 μm.

[0163] When the resin layer is a transparent, high-heat-resistant resin layer, its yellowness index (hereinafter also referred to as "yellow index" or "YI") is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 3 or less. The lower limit of the yellowness index of the transparent resin layer is not particularly limited, but for use as a flexible electronic device, it is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.

[0164] The light transmittance of the transparent, heat-resistant resin layer at a wavelength of 400 nm in the present invention is preferably 70% or more, more preferably 72% or more, even more preferably 75% or more, and even more preferably 80% or more. There is no particular upper limit to the light transmittance of the transparent resin layer at a wavelength of 400 nm, but for use as a flexible electronic device, it is preferably 99% or less, more preferably 98% or less, and even more preferably 97% or less.

[0165] The haze of the transparent, heat-resistant resin layer in the present invention is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and even more preferably 0.3 or less. The lower limit is not particularly limited, but industrially speaking, a value of 0.01 or more is acceptable, and a value of 0.05 or more is also acceptable.

[0166] The average coefficient of linear expansion (CTE) of the resin layer between 30°C and 250°C is preferably 50 ppm / K or less. More preferably 45 ppm / K or less, even more preferably 40 ppm / K or less, even more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less. It is also preferably -5 ppm / K or more, more preferably -3 ppm / K or more, and even more preferably 1 ppm / K or more. When the CTE is within the above range, the difference in the coefficient of linear expansion with a general support (inorganic substrate) can be kept small, and peeling of the resin layer from the inorganic substrate or warping of the support can be avoided even when subjected to a heat-applying process. Here, CTE is a factor that represents reversible expansion and contraction with respect to temperature. Note that the CTE of the resin layer refers to the average value of the CTE in the flow direction (MD direction) and the CTE in the width direction (TD direction) of the resin layer.

[0167] In the present invention, the thickness of the resin layer is preferably 5 μm or more, more preferably 8 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. There is no particular upper limit to the thickness of the resin layer, but for use as a flexible electronic device, it is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 90 μm or less. When the thickness of the resin layer is 5 μm or more, it becomes easier to produce a stable and uniform resin layer, and when the thickness of the resin layer is 200 μm or less, it becomes easier to completely remove the solvent while maintaining the physical properties, and the flexibility of the flexible substrate is also easily exhibited.

[0168] The tensile modulus of the resin layer is preferably 1 GPa or more, more preferably 2 GPa or more, and even more preferably 3 GPa or more. There is no particular upper limit to the tensile modulus, but it is about 15 GPa. If the tensile modulus is 15 GPa or less, the resin layer can be used as a flexible resin layer. If the tensile modulus is 4 GPa or more, excessive elongation is less likely to occur during handling.

[0169] The number of gel defects per unit area of ​​the aforementioned resin layer is 0 to 10 defects / m². 2Preferably, 0 to 8 pieces / m 2 More preferably, 0-5 pieces / m 2 This is even more preferable. The number of gel defects per unit area is 20 / m². 2 The following conditions will allow for more effective suppression of deterioration in physical properties and appearance due to gel defects. <Manufacturing method for flexible circuit boards> A method for manufacturing a flexible substrate, which is one embodiment of the present invention, includes a functional layer formation step of forming a functional layer on the resin layer of the laminate obtained by the above-described method for manufacturing a laminate, and a separation step of peeling the resin layer from the support to obtain a flexible substrate having the functional layer on the resin layer. <Functional Layer> In the present invention, a functional layer refers to a layer or various functional material layer that constitutes a display device such as a liquid crystal display device, an organic EL display device, electronic paper, or a touch panel, a lighting device, a detection device, or a component thereof. Specifically, it means one or more types of layers such as an electrode layer, a light-emitting layer, a gas barrier layer, an adhesive layer, a bonding layer, a sticky layer, a thin-film transistor, a wiring layer, or a transparent conductive layer.

[0170] Resin layers with functional layers are used, for example, in organic EL lighting devices, as conductive resin layers laminated with ITO, as gas barrier resin layers that prevent the penetration of moisture and oxygen, and as flexible substrates which are functional materials with various functions such as components for flexible circuit boards. <Flexible circuit board> A resin layer with a functional layer is called a flexible substrate, and it is an electronic device element or component that has enough flexibility to be bent by hand. The form in which the flexible substrate is mounted in an electronic device may be a bending application where the curvature changes during use, a fixed curved surface where the curvature does not change, or a flat surface.

[0171] In this invention, the resin layer can be removed from the support by mechanical peeling or by laser light. When the peeling strength is above a certain level, it is preferable to use laser light.

[0172] <Laser light> Examples of lasers include various gas lasers and solid-state lasers (semiconductor lasers), such as excimer lasers, Nd-YAG lasers, Ar lasers, CO2 lasers, and He-Ne lasers. Depending on the wavelength, these lasers can be used for UV (below 410 nm), green, and visible light regions. Band laser (500~700nm), near infrared region Band laser (700~2000nm), infrared region Band laser They can be broadly categorized into (2000nm and above), etc.

[0173] In this invention, a laser light with a wavelength of 410 nm or less is used as the UV laser, and more specifically, a laser light having any wavelength in the wavelength range of 300 nm to 410 nm is irradiated from the other side of the support. In particular, the third harmonic (355 nm) of an Nd-YAG laser with a wavelength of 360 nm or less is preferred, and even more preferably is a Xe-Cl excimer laser (308 nm) with a wavelength of 310 nm or less.

[0174] In this invention, it is preferable to irradiate the entire back surface of the support opposite to the surface on which the resin layer is formed. Methods for irradiating the entire surface of the support include fixing the laser nozzle and moving the stage in the XY direction while irradiating, or moving the laser nozzle in the XY direction while irradiating. The laser nozzle shape can be arbitrarily selected, for example, a point laser or a line laser. In this invention, irradiation with a line laser having the widest possible irradiation width is preferred.

[0175] Preferably, in this invention, laser irradiation is performed in pulses while moving the nozzle. The laser intensity is distributed within the irradiation range, and generally the intensity is stronger in the center and weaker in the peripheral areas. Therefore, when irradiating with a laser, the laser intensity should be as uniform as possible, or the irradiation range should overlap in some areas. A smaller overlap is preferable as it allows for a faster irradiation speed.

[0176] Furthermore, when irradiating with overlapping laser irradiation areas, strong energy is applied to the overlapping areas, which may alter the resin layer through the support. Therefore, it is preferable to irradiate the support multiple times from the other side so that the overlap width of the laser beams is 50% or less of the beam width, preferably 30% or less.

[0177] If the laser irradiation energy is too strong, it may alter the resin layer, and if it is too weak, the resin layer may not peel off from the support. Therefore, the irradiation energy of the laser beam hitting the other side of the support should be between 10 mJ and 500 mJ, preferably between 80 mJ and 300 mJ. Here, the irradiation energy of the laser beam hitting the other side of the support is determined by the energy density (mJ / cm³). 2 This is the sum of the energies, taking into account the overlap of the beams. [Examples]

[0178] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way to these examples. In this invention, physical properties, etc., were measured or evaluated by the following methods.

[0179] <Tensile Test> Test specimens were prepared by cutting polyimide film into strips measuring 100 mm x 10 mm in both the flow direction (MD direction) and the width direction (TD direction). Using a tensile testing machine (Shimadzu Corporation, Autograph, model AG-5000A), the tensile modulus, elongation, and breaking strength were measured in both the MD and TD directions under conditions of a tensile speed of 50 mm / min and a chuck distance of 40 mm. The average values ​​for both the MD and TD directions were then calculated. The results are shown in Tables 1A and 1B.

[0180] <Counting the number of gel defects in polyimide film> A long polyimide film was illuminated with an incandescent lamp and driven 20 meters, and defects were checked through a polarizing plate. Of the identified defects, those that appeared dark (dark defects) were excluded as they were thought to be caused by foreign matter such as iron powder, and the defects that appeared bright (bright defects) were examined in detail over 1000 meters. 2 The number of gel defects per unit area was counted.

[0181] <Count of gel defects in the resin layer> The resin layer with the support was illuminated with an incandescent lamp, and defects were checked through a polarizing plate. Of the identified defects, dark defects were excluded as they were thought to be caused by foreign matter such as iron powder, and the bright defects were examined in detail, and the number of gel defects was counted. The number of gel defects was counted for 10 resin layers prepared under each condition, and 1 m 2 The number of gel defects per unit area was calculated.

[0182] <Peel strength between polyamic acid film and support> A laminate of a self-supporting polyamic acid film and a support was sampled, i.e., the laminate immediately before the peeling process, before gripping with a pin tenter. If the polyamic acid film is peeled directly from the support, the polyamic acid film stretches, making it impossible to measure the peel strength accurately. Therefore, Scotch Mending Tape (3M) was applied over the polyamic acid, and the laminate of tape / polyamic acid film / support was cut to match the width of the tape. The support side was fixed to the stage with double-sided tape, and the polyamic acid film, along with the tape, was gripped with a chuck to measure the 90° peel strength between the support and the polyamic acid film. The measurement conditions for the 90° peel strength are as follows.

[0183] The polyamic acid film is peeled off from the fixed support at a 90° angle. Five measurements are taken, and the average value is used as the measurement value. Measuring device: JSV-H1000, manufactured by Nippon Keisoku System Co., Ltd. Measurement temperature; room temperature (25℃) Peeling speed: 100 mm / min Atmosphere; atmosphere Measurement sample width: 1.2 cm <Observation of color unevenness> For colored polyimide films, 10cm square samples were cut from the left and right edges and the center of the entire film width, placed on white fine paper, and visually inspected under fluorescent light to check for color unevenness. The same procedure was performed at four locations at least 2m apart in the MD direction, and evaluated according to the following criteria. ◎: No color unevenness was observed in any of the 12 locations in the 3x4 grid. ○: Color unevenness was observed in 1 to 2 out of 12 locations. ×: Color unevenness was observed in 3 or more of the 12 locations.

[0184] <Yellow Index (YI)> For transparent polyimide films, the tristimulus values ​​(XYZ) of the film were measured according to ASTM D1925 using a colorimeter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, and the yellowness index (YI) was calculated using the following formula. Three similar measurements were performed, and the arithmetic mean was adopted.

[0185] YI = 100 × (1.28X - 1.06Z) / Y

[0186] <Reduced viscosity> A solution was prepared by adding N,N-dimethylacetamide (DMAc) to dissolve the resin so that the resin concentration was 0.2 g / dl. Ubbelohde type The viscosity was measured at 25°C using a viscosity tube.

[0187] <Warpage of a resin layer and glass laminate after heating at 300°C for 1 hour> The amount of warpage was measured for the obtained polyimide resin layer and glass laminates F1 to F8. The warpage (μm) of the laminate refers to the degree of deformation in the thickness direction relative to the surface direction of the laminate before and after the predetermined heat treatment described below. Specifically, as shown in Figure 1, a 100 mm × 100 mm test piece 12 was placed on a surface plate 11 at room temperature with the test piece in a concave shape, and the average value of the distances from the plane at the four corners (h1rt, h2rt, h3rt, h4rt: unit mm) was taken as the original amount of warpage (mm). After heat treatment at 300°C for 1 hour, the test piece was placed on a plane with the test piece in a concave shape, and the average value of the distances from the plane at the four corners (h1, h2, h3, h4: unit mm) was taken as the amount of warpage (mm), and the difference from the original amount of warpage was taken as the amount of warpage after heating at 300°C for 1 hour. The measured value was the average of 10 points.

[0188] However, if there is not enough laminate to take 10 samples, measurements should be taken using three or more layers. Specifically, the following formula is used for calculation.

[0189] Original curvature (μm) = (h1rt + h2rt + h3rt + h4rt) / 4 Curvature (μm) = (h1 + h2 + h3 + h4) / 4 Warpage at 300℃ (μm) = Warpage - Original Warpage

[0190] <Warpage of the resin layer after peeling> For laminates F2, F3, and F7, after heat treatment at 300°C for 1 hour, the resin layer was mechanically peeled from the support, cut to a size of 100 mm x 100 mm, and then placed on a surface plate at room temperature so that it was concave. The height from the surface plate at each of the four corners was measured using a VH-Z20R (manufactured by Keyence), and the average value was defined as the warp of the resin layer. For each film, five 100 mm x 100 mm test pieces were used to calculate the average value.

[0191] For laminates F1, F4, F5, F6, and F8-F10, the resin layer was peeled from the support using a laser, and the amount of warping was measured in the same manner. Laser peeling was performed by irradiating the glass side with a laser beam of 308 nm (pulse width 50 ns, beam size 14 mm x 1.2 mm) and a moving speed of 6 mm / s using an industrial excimer laser, LightMachinery IPEX-840. Specifically, the overlap width of the laser beam was set to 2 mm to ensure a uniform energy distribution across the entire glass side of the laminate, and the laser beam was irradiated multiple times onto the back surface of the glass substrate over five passes.

[0192] <Synthesis Example 1-1 (Preparation of Polyamic Acid Solution 1-1)> To achieve a monomer molar ratio of ODA / PMDA = 1 / 1 and a monomer concentration of 15% by mass, a container equipped with a nitrogen inlet tube, thermometer, and stirring rod was purged with nitrogen. 3,3'-diaminodiphenyl ether (ODA) was added, followed by N,N-dimethylacetamide (DMAc), which was completely dissolved. Then, pyromellitic dianhydride (PMDA) was added. Polymerization was carried out by stirring at 25°C for 5 hours, yielding a brown, viscous polyamic acid solution 1-1. The reduced viscosity (ηsp / C) was 2.1 dl / g.

[0193] <Synthesis Example 1-2 (Preparation of Polyamic Acid Solution 1-2)> After purging the reaction vessel, equipped with a nitrogen inlet tube, thermometer, and stirring rod, with nitrogen, 300 parts by mass of 5-amino-2-(p-aminophenyl)benzoxazole (p-DAMBO) were charged. Next, 4400 parts by mass of DMAc were added and dissolved completely, then 300 parts by mass of pyromellitic dianhydride were added, and the mixture was stirred at a reaction temperature of 25°C for 17 hours to obtain a brown, viscous polyamic acid solution 1-2. The reduced viscosity (ηsp / C) was 4.1 dl / g.

[0194] <Synthesis Example 1-3 (Preparation of Polyamic Acid Solution 1-3)> After purging the reaction vessel, equipped with a nitrogen inlet tube, reflux tube, and stirring rod, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") consisting of 19.86 parts by mass of 4,4'-diaminodiphenyl sulfone (4,4'-DDS), 4.97 parts by mass of 3,3'-diaminodiphenyl sulfone (3,3'-DDS), 103.7 parts by mass of N,N-dimethylacetamide (DMAc), and colloidal silica as a lubricant dispersed in dimethylacetamide was prepared, and the silica (lubricant) was used to determine the total amount of polymer solids in the polyamic acid solution. 0.4% by mass Add and dissolve completely, then add 31.02 parts by mass of 4,4'-oxydiphthalate acid dianhydride (ODPA) was added in solid form in divided portions, and the mixture was stirred at room temperature for 24 hours. The reduced viscosity (ηsp / C) of the resulting polyamic acid solutions 1-3 was 0.70 dl / g.

[0195] <Synthesis Example 1-4 (Preparation of Polyamic Acid Solution 1-4)> In a reaction vessel equipped with a nitrogen inlet tube, reflux tube, and stirring rod, 32.02 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) and 230 parts by mass of N,N-dimethylacetamide (DMAc) were added while introducing nitrogen gas, and the mixture was completely dissolved. Then, 44.42 parts by mass of 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA) was added in solid form in fractions (molar ratio of 6FDA / TFMB = 1.00 / 1.00), and the mixture was stirred at room temperature for 24 hours. The reduced viscosity (ηsp / C) of the resulting polyamic acid solution 1-4 was 1.10 dl / g.

[0196] <Synthesis Example 1-5 (Preparation of Polyamic Acid Solution 1-5)> After purging the reaction vessel, equipped with a nitrogen inlet tube, reflux tube, and stirring rod, with nitrogen, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") consisting of 33.36 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 336.31 parts by mass of N-methyl-2-pyrrolidone (NMP), and colloidal silica as a lubricant dispersed in dimethylacetamide is used, and the silica (lubricant) is used in a polyamic acid solution by an amount equal to the total polymer solids content. 0.3% by mass Add the mixture until completely dissolved, then add 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarbon acid dianhydride (CBDA), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic acid (BPDA), and 4.85 parts by mass of 4,4'-oxydiphthalate acid dianhydride After adding each of the (ODPA) components in solid form in divided portions, the mixture was stirred at room temperature for 24 hours. Subsequently, polyamic acid solutions 1-5 with a solid content of 15% by mass and a reduced viscosity of 3.50 dl / g (molar ratio of TFMB / / CBDA / BPDA / ODPA = 1.00 / / 0.48 / 0.37 / 0.15) were obtained.

[0197] <Synthesis Example 1-6 (Preparation of Polyamic Acid Solution 1-6)> A double-decker type silsesquioxane derivative (AASQ1) containing an acid anhydride group, represented by the structure of formula (1), was obtained from Nippon Materials Technology Co., Ltd.

[0198] [ka]

[0199] Next, after purging the reaction vessel, which is equipped with a nitrogen inlet tube, reflux tube, and stirring rod, with nitrogen, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") consisting of 490.2 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 5340 parts by mass of N-methyl-2-pyrrolidone (NMP), and colloidal silica as a lubricant dispersed in dimethylacetamide was added so that the silica (lubricant) amounted to 0.3% by mass of the total polymer solids in the polyamic acid solution, and the mixture was completely dissolved. Then, 327.2 parts by mass of pyromellitic dianhydride (PMDA) and 45.4 parts by mass of AASQ1 were added in solid form, and the mixture was stirred at room temperature for 24 hours. Subsequently, a polyamic acid solution 1-6 with a solid content of 14% by mass and a reduced viscosity of 1.46 dl / g (molar ratio of TFMB / / PMDA / AASQ1 = 1.00 / / 0.98 / 0.02) was obtained.

[0200] <Synthesis Example 1-7 (Preparation of Polyamic Acid Solution 1-7)> A double-decker type silsesquioxane derivative containing an amino group (AMSQ1), represented by the structure of formula (2), was produced by the method described in Japanese Patent Application Publication No. 2006-265243.

[0201] [ka]

[0202] Next, after purging the reaction vessel, which is equipped with a nitrogen inlet tube, reflux tube, and stirring rod, with nitrogen, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") consisting of 470.8 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 39.9 parts by mass of AMSQ1, 6880 parts by mass of N-methyl-2-pyrrolidone (NMP), and colloidal silica as a lubricant dispersed in dimethylacetamide was added so that the silica (lubricant) amounted to 0.3% by mass of the total polymer solids in the polyamic acid solution, and the mixture was completely dissolved. Then, 325.6 parts by mass of pyromellitic dianhydride (PMDA) was added in solid form, and the mixture was stirred at room temperature for 24 hours. Subsequently, a polyamic acid solution 1-7 with a solid content of 11% by mass and a reduced viscosity of 3.50 dl / g (molar ratio of TFMB / AMSQ1 / / PMDA = 0.98 / 0.02 / / 1.00) was obtained.

[0203] <Example 1-1 (Preparation of polyimide film F1)> A DMAc solution of isoquinoline (melting point 26°C) (10% by mass) was applied to the smooth (untreated) surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a wire coater with a gap of 100 μm. The film was then passed through a 90°C furnace for 3 minutes to obtain a concentrated liquid coating of isoquinoline. The amount of isoquinoline applied (abundant) was 7.36 mg / m² per 1 μm of the resulting polyimide film thickness. 2 That was the case.

[0204] On top of that, polyamic acid solution 1-1 obtained in Synthesis Example 1-1 was coated using a comma coater so that the final film thickness (film thickness of the polyimide film) was 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the A4100 support and passed through a pin tenter having a pin sheet with pins arranged on it. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets so as not to break the film and so as not to cause unnecessary slack. It was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 400°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and it was wound into a roll to obtain 200 m of polyimide film F1 with a width of 450 mm.

[0205] <Example 1-2 (Preparation of polyimide film F2)> Polyimide film F2 was obtained in the same manner as in Example 1-1, except that a DMAc solution of pyridine (melting point -41.6°C) (concentration 10% by mass) was used instead of the isoquinoline solution, and polyamic acid solution 1-2 was used instead of polyamic acid solution 1-1. The amount of pyridine applied (amount present) was 98.2 mg / m² per 1 μm of the thickness of the resulting polyimide film. 2 That was the case.

[0206] <Example 1-3 (Preparation of Polyimide Film F3)> A DMAc solution of isoquinoline (10% by mass) was applied to the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a wire coater with a gap of 100 μm. The film was then passed through a 90°C furnace for 3 minutes to obtain a concentrated liquid coating of isoquinoline. The amount of isoquinoline applied (abundant) was 7.36 mg / m² per 1 μm of the resulting polyimide film thickness. 2 That was the case.

[0207] On top of that, polyamic acid solution 1-3 obtained in Synthesis Example 1-3 was coated using a comma coater to achieve a final film thickness of 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. It was then heated at 180°C for 3 minutes, 230°C for 3 minutes, and 280°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, and the parts with poor flatness at both ends of the film were cut off with a slitter. The film was then wound into a roll to obtain 200 m of polyimide film F3 with a width of 450 mm.

[0208] <Example 1-4 (Preparation of Polyimide Film F4)> Polyimide film F4 was obtained in the same manner as in Examples 1-3, except that a pyridine DMAc solution (10% by mass) was used instead of the isoquinoline solution, and polyamic acid solution 1-4 was used instead of polyamic acid solution 1-3. The amount of pyridine applied (amount present) was 98.2 mg / m² per 1 μm of thickness of the resulting polyimide film. 2 That was the case.

[0209] <Comparative Example 1-1 (Preparation of Polyimide Film F5)> To the polyamic acid solution 1-1 obtained in Synthesis Example 1-1, an isoquinoline DMAc solution (concentration 10% by mass) was added so that the mass ratio of isoquinoline was 10% by mass. The mixture was then continuously stirred with a mixer, and the resulting isoquinoline-containing polyamic acid solution was immediately coated using a comma coater. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 400°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F5 with a width of 450 mm.

[0210] <Comparative Example 1-2 (Preparation of Polyimide Film F6)> Pyridine was added to the polyamic acid solution 1-4 obtained in Synthesis Example 1-4 so that the mass ratio of pyridine was 10% by mass. The mixture was then continuously stirred with a mixer, and the resulting pyridine-containing polyamic acid solution was immediately coated using a comma coater. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 180°C for 3 minutes, 230°C for 3 minutes, and 280°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F6 with a width of 450 mm.

[0211] <Comparative Example 1-3 (Preparation of Polyimide Film F7)> Polyamic acid solution 1-2 obtained in Synthesis Example 1-2 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 400°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F8 with a width of 450 mm.

[0212] <Comparative Example 1-4 (Preparation of Polyimide Film F8)> Polyamic acid solution 1-3 obtained in Synthesis Example 1-3 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 180°C for 3 minutes, 230°C for 3 minutes, and 280°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F8 with a width of 450 mm.

[0213] <Comparative Example 1-5 (Preparation of Polyimide Film F9)> Polyamic acid solution 1-1 obtained in Synthesis Example 1-1 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 150°C for 5 minutes and then at 200°C for 5 minutes. After drying, an attempt was made to peel the self-supporting polyamic acid film from the A4100 support, but the surface layer partially peeled off towards the support, making it impossible to obtain a long film.

[0214] <Comparative Example 1-6 (Preparation of Polyimide Film F10)> Polyamic acid solution 1-3 obtained in Synthesis Example 1-3 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 that had served as the support, passed through a pin tenter having a pin sheet with pins, and the film ends were gripped by inserting them into the pins. The film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack, and then heated at 180°C for 3 minutes, 230°C for 3 minutes, and 280°C. 5 minutes, The film was heated at 330°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature for 2 minutes, and the parts with poor flatness at both ends of the film were cut off with a slitter. The film was then rolled up to obtain 200m of polyimide film F10 with a width of 450mm.

[0215] <Comparative Example 1-7 (Preparation of Polyimide Film F11)> Polyamic acid solution 1-1 obtained in Synthesis Example 1-1 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, 400°C for 5 minutes, and 480°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F11 with a width of 450 mm.

[0216] <Examples 1-5 (Preparation of Polyimide Film F12)> Polyimide film F12 was obtained in the same manner as in Example 1-3, except that polyamic acid solution 1-5 was used instead of polyamic acid solution 1-3, the drying temperature of the polyamic acid solution was set to 90°C for 15 minutes, and the temperature conditions during pin tenter transport were set to 180°C for 3 minutes, 230°C for 3 minutes, and 300°C for 3 minutes.

[0217] <Examples 1-6 (Preparation of Polyimide Film F13)> Polyimide film F13 was obtained in the same manner as in Example 1-3, except that polyamic acid solution 1-6 was used instead of polyamic acid solution 1-3, the drying temperature of the polyamic acid solution was set to 90°C for 15 minutes, and the temperature conditions during pin tenter transport were set to 180°C for 3 minutes, 250°C for 3 minutes, and 320°C for 3 minutes.

[0218] <Example 1-7 (Preparation of Polyimide Film F14)> Polyimide film F14 was obtained in the same manner as in Example 1-3, except that polyamic acid solution 1-7 was used instead of polyamic acid solution 1-3, the drying temperature of the polyamic acid solution was set to 90°C for 15 minutes, and the temperature conditions during pin tenter transport were set to 180°C for 3 minutes, 250°C for 3 minutes, and 330°C for 3 minutes.

[0219] <Comparative Example 1-8 (Preparation of Polyimide Film F15)> Polyamic acid solution 1-5 obtained in Synthesis Example 1-5 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 90°C for 15 minutes. After drying, the self-supporting polyamic acid film was peeled from the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 180°C for 3 minutes, 230°C for 3 minutes, 280°C for 5 minutes, and 350°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F15 with a width of 450 mm.

[0220] <Comparative Example 1-9 (Preparation of Polyimide Film F16)> Polyamic acid solution 1-6 obtained in Synthesis Example 1-6 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 90°C for 15 minutes. After drying, the self-supporting polyamic acid film was peeled off the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 180°C for 3 minutes, 230°C for 3 minutes, 300°C for 5 minutes, and 370°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, and the parts with poor flatness at both ends of the film were cut off with a slitter. The film was then wound into a roll to obtain 200 m of polyimide film F16 with a width of 450 mm.

[0221] <Comparative Example 1-10 (Preparation of Polyimide Film F17)> Polyamic acid solution 1-7 obtained in Synthesis Example 1-7 was coated onto the smooth surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to achieve a final film thickness of 15 μm. This was dried at 90°C for 15 minutes. After drying, the self-supporting polyamic acid film was peeled off from the A4100 support and passed through a pin tenter having a pin sheet with pins. The film ends were gripped by inserting them into the pins, and the film was transported while adjusting the spacing between the pin sheets to prevent breakage and unnecessary slack. The film was then heated at 180°C for 3 minutes, 250°C for 3 minutes, 320°C for 5 minutes, and 400°C for 5 minutes to allow the imidation reaction to proceed. After that, it was cooled to room temperature in 2 minutes, the parts with poor flatness at both ends of the film were cut off with a slitter, and the film was wound into a roll to obtain 200 m of polyimide film F17 with a width of 450 mm.

[0222] <Rating> For films F1 to F17 obtained in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-10, tensile tests, counting of gel defects, and measurement of peel strength between the polyamic acid film and support were performed. For the brown films F1, F2, F5, F7, F9, and F11, color unevenness was observed, and for the other films, YI was measured. The results are shown in Tables 1A to 1B.

[0223] [Table 1A]

[0224] [Table 1B]

[0225] As shown in the results in Tables 1A to 1B, in Examples 1-1 to 1-7, in which the reaction accelerator was pre-coated to the support, the decrease in tensile modulus, elongation, and breaking strength due to gel defects, as well as color unevenness, were suppressed compared to the comparative example using the same polyamic acid solution. Furthermore, the increase in the yellow index (YI) and the increase in the peel strength of the support were suppressed.

[0226] In contrast, among the comparative examples using the same polyamic acid solution as Example 1-1, Comparative Example 1-1, which used a reaction accelerator, showed a decrease in tensile modulus, elongation, and breaking strength due to an increase in gel defects, as well as an increase in color unevenness, and also an increase in peel strength. Furthermore, in Comparative Examples 1-5 and 1-7, which employed the thermal imidization method, gel defects were less likely to occur, but the increase in peel strength was significant.

[0227] Furthermore, in Comparative Examples 1-3, which used the same polyamic acid solution as in Examples 1-2 and performed thermal imidation at a relatively low temperature, the imidation reaction was insufficient, resulting in a decrease in tensile modulus, elongation, and breaking strength, as well as an increase in color unevenness.

[0228] Among the comparative examples using the same polyamic acid solution as in Examples 1-3, Comparative Example 1-4, in which thermal imidation was performed at a relatively low temperature, showed insufficient imidation reaction, resulting in a decrease in tensile modulus, elongation, and breaking strength. In Comparative Example 1-6, in which thermal imidation was performed at a relatively high temperature, the tensile modulus, elongation, and breaking strength were similar to those of Examples 1-3, but there was a significant increase in the yellow index (YI) and peel strength.

[0229] In Comparative Example 1-2, which used the same polyamic acid solution as in Example 1-4 but mixed with a reaction accelerator, a decrease in tensile modulus, elongation, and fracture strength was observed due to an increase in gel defects, while peel strength also increased.

[0230] In Comparative Examples 1-8 to 1-10, which used the same polyamic acid solution as Examples 1-5 to 1-7, the tensile modulus, elongation, and breaking strength were similar to those of Examples 1-5 to 1-7, but there was a significant increase in the yellow index (YI) and peel strength.

[0231] <Synthesis Example 2-1 (Preparation of Polyamic Acid Solution 2-1)> To achieve a monomer molar ratio of ODA / PMDA = 1 / 1 and a monomer concentration of 15% by mass, a container equipped with a nitrogen inlet tube, thermometer, and stirring rod was purged with nitrogen. 3,3'-diaminodiphenyl ether (ODA) was added, followed by N,N-dimethylacetamide (DMAc), which was completely dissolved. Then, pyromellitic dianhydride (PMDA) was added. Polymerization was carried out by stirring at 25°C for 5 hours, yielding a brown, viscous polyamic acid solution 2-1. The reduced viscosity (ηsp / C) was 2.1 dl / g.

[0232] <Synthesis Example 2-2 (Preparation of Polyamic Acid Solution 2-2)> After purging the reaction vessel, equipped with a nitrogen inlet tube, thermometer, and stirring rod, with nitrogen, 300 parts by mass of 5-amino-2-(p-aminophenyl)benzoxazole (p-DAMBO) were charged. Next, 4400 parts by mass of DMAc were added and dissolved completely, then 300 parts by mass of pyromellitic dianhydride were added, and the mixture was stirred at a reaction temperature of 25°C for 17 hours to obtain a brown, viscous polyamic acid solution 2-2. The reduced viscosity (ηsp / C) was 4.1 dl / g.

[0233] <Synthesis Example 2-3 (Preparation of Polyamic Acid Solution 2-3)> After purging the reaction vessel, which is equipped with a nitrogen inlet tube, reflux tube, and stirring rod, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") is prepared by dispersing 22.0 parts by mass of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 252.1 parts by mass of DMAc, and colloidal silica (average particle size 80 nm) as a lubricant in dimethylacetamide. In polyamic acid solution The polymer solids were added to a total of 0.4% by mass and completely dissolved. Then, 22.0 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added in solid form, and the mixture was stirred at room temperature for 24 hours. Subsequently, 165.7 parts by mass of DMAc were added to dilute the mixture, yielding polyamic acid solution 2-3 with a solids content (NV) of 11% by mass and a reduced viscosity of 3.5 dl / g.

[0234] <Synthesis Example 2-4 (Preparation of Polyamic Acid Solution 2-4)> After purging the reaction vessel, equipped with a nitrogen inlet tube, reflux tube, and stirring rod, with nitrogen, a dispersion (Nissan Chemical Industries' "Snowtex® DMAC-ST-ZL") consisting of 8.9334 parts by mass of TFMB, 70 parts by mass of DMAc, and colloidal silica dispersed in dimethylacetamide as a lubricant was added so that the silica (lubricant) amounted to 0.4% by mass of the total polymer solids in the polyamic acid solution, and the mixture was completely dissolved. Then, 6.0666 parts by mass of PMDA was added in installments, followed by the addition of 85 parts by mass of DMAc, and the mixture was stirred at room temperature for 6 hours. The resulting polyamic acid solution 2-4 was clear, with a solids content (Nv) of 15% by mass and a reduced viscosity of 4.4 dl / g.

[0235] <Synthesis Example 2-5 (Preparation of Polyamic Acid Solution 2-5)> An amino group-containing double-decker type silsesquioxane derivative (AMSQ1) represented by the structure of the following formula (2) was produced by the method described in JP-A-2006-265243.

[0236]

Chemical Formula

[0237] Next, after replacing the inside of a reaction vessel equipped with a nitrogen introduction tube, a reflux tube, and a stirring rod with nitrogen, 470.8 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 39.9 parts by mass of AMSQ1, 6880 parts by mass of N-methyl-2-pyrrolidone (NMP), and a dispersion obtained by dispersing colloidal silica as a lubricant in dimethylacetamide (manufactured by Nissan Chemical Industries, Ltd., "Snowtex (registered trademark) DMAC-ST-ZL") were added so that the silica (lubricant) became 0.3% by mass based on the total amount of the polymer solid content in the polyamic acid solution and completely dissolved. Then, 325.6 parts by mass of pyromellitic dianhydride (PMDA) was added in portions as a solid, and then stirred at room temperature for 24 hours. Thereafter, a polyamic acid solution 2-5 having a solid content of 11% by mass and a reduced viscosity of 3.50 dl / g (molar ratio of TFMB / AMSQ1 / / PMDA = 0.98 / 0.02 / / 1.00) was obtained.

[0238] <Example 2-1 (Production of Laminate F1 of Polyimide Resin Layer and Glass)> A DMAc solution (concentration: 10% by mass) of isoquinoline (melting point 26°C) was coated on a square non-alkali glass (manufactured by Corning, Inc., Eagle 2000) with sides of 150 mm and a thickness of 0.7 mm at a gap of 100 μm using a wire coater, and then heated in a furnace at 90°C for 3 minutes to obtain a liquid coating film in which isoquinoline was concentrated. The coating amount (amount present) of isoquinoline was 7.36 mg / m per 1 μm thickness of the resulting polyimide resin layer. 2 It was.

[0239] From above, the polyamic acid solution 2-1 was cast with a bar coater so that the dry thickness became 15 μm, and dried at 90 °C for 1 hour in a hot air oven. Then, the temperature was gradually raised to 400 °C at 5 °C / min, and further heated for 10 min to imidize, thereby obtaining a laminate F1 of a polyimide resin layer with a thickness of about 15 μm and glass.

[0240] <Example 2-2 (Production of laminate F2 of polyimide resin layer and glass)> In Example 2-1, a DMAc solution (concentration 10% by mass) of pyridine (melting point -41.6 °C) was used instead of the isoquinoline solution, and polyamic acid solution 2-2 was used instead of polyamic acid solution 2-1. A laminate F2 of a polyimide resin layer and glass was obtained in the same manner as in Example 2-1, except that the final heat treatment temperature was 450 °C. The coating amount (amount present) of pyridine was 98.2 mg / m per 1 μm thickness of the resulting polyimide resin layer. 2 It was.

[0241] <Example 2-3 (Production of laminate F3 of polyimide resin layer and glass)> In Example 2-1, polyamic acid solution 2-3 was used instead of polyamic acid solution 2-1, and a laminate F3 of a polyimide resin layer and glass was obtained in the same manner as in Example 2-1, except that the final heat treatment temperature was 300 °C.

[0242] <Example 2-4 (Production of laminate F4 of polyimide resin layer and glass)> In Example 2-1, a DMAc solution (concentration 10% by mass) of pyridine (melting point -41.6 °C) was used instead of the isoquinoline solution, and polyamic acid solution 2-4 was used instead of polyamic acid solution 2-1. A laminate F4 of a polyimide resin layer and glass was obtained in the same manner as in Example 2-1, except that the final heat treatment temperature was 360 °C.

[0243] <Comparative Example 2-1 (Production of laminate F5 of polyimide resin layer and glass)> To the polyamic acid solution 2-1 obtained in Synthesis Example 2-1, an isoquinoline DMAc solution (concentration 10% by mass) was added so that the mass ratio of isoquinoline was 10% by mass. The mixture was then continuously stirred with a mixer, and the resulting isoquinoline-containing polyamide solution was immediately cast onto a square of alkali-free glass (Corning Eagle 2000) with sides of 150 mm and a thickness of 0.7 mm using a bar coater to a dry thickness of 15 μm, and dried in a hot air oven at 90°C for 1 hour. Subsequently, the temperature was gradually increased to 400°C at a rate of 5°C / min, and then heated for another 10 minutes to imidize, thereby obtaining a laminate F5 of polyimide resin and glass with a thickness of approximately 15 μm.

[0244] <Comparative Example 2-2 (Preparation of Laminate F6 of Polyimide Resin Layer and Glass)> A laminate of polyimide resin and glass F6 was obtained in the same manner as in Comparative Example 2-1, except that pyridine was used in a mass ratio of 10% by mass instead of isoquinoline, polyamic acid solution 2-4 was used instead of polyamic acid solution 2-1, and the final heat treatment temperature was 360°C.

[0245] <Comparative Example 2-3 (Preparation of a laminate F7 of polyimide resin layer and glass)> Polyamic acid solution 2-3 was cast onto a square of alkali-free glass (Corning Eagle 2000) with sides of 150 mm and a thickness of 0.7 mm using a bar coater to a dry thickness of 15 μm, and dried in a hot air oven at 90°C for 1 hour. Subsequently, the temperature was gradually increased to 300°C at a rate of 5°C / min, and then heated for another 10 minutes to imidize the glass, thereby obtaining a laminate F7 of a polyimide resin layer and glass with a thickness of approximately 15 μm.

[0246] <Comparative Example 2-4 (Fabrication of a laminate F8 of polyimide resin layer and glass)> In Comparative Example 2-3, a laminate of polyimide resin and glass F8 was obtained in the same manner as in Comparative Example 2-3, except that polyamic acid solution 2-1 was used instead of polyamic acid solution 2-3 and the final heat treatment temperature was set to 400°C.

[0247] <Example 2-5 (Fabrication of a polyimide resin layer and glass laminate F9)> A laminate of polyimide resin and glass F9 was obtained in the same manner as in Example 2-1, except that polyamic acid solution 2-5 was used instead of polyamic acid solution 2-1 and the final heat treatment temperature was set to 330°C.

[0248] <Comparative Example 2-5 (Preparation of a laminate F10 of polyimide resin layer and glass)> In Comparative Example 2-3, a polyimide resin layer and glass laminate F10 was obtained in the same manner as in Comparative Example 2-3, except that polyamic acid solution 2-5 was used instead of polyamic acid solution 2-3 and the final heat treatment temperature was set to 400°C.

[0249] <Rating> For the laminates F1 to F10 obtained in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-5, the warpage of the laminate, the warpage of the resin layer, and the number of gel defects were measured. The results are shown in Table 2.

[0250] [Table 2]

[0251] As shown in the results in Table 2, in Examples 2-1 to 2-5, where the reaction accelerator was pre-coated to the support, warping of the laminate and warping of the resin layer after delamination were all reduced. Furthermore, gel defects were suppressed compared to the case where the reaction accelerator was added to the polyamic acid solution.

[0252] In contrast, among the comparative examples using the same polyamic acid solution as Example 2-1, Comparative Example 2-1, which used a reaction accelerator mixed in, showed an increase in gel defects, resulting in increased warping of the laminate and the resin layer after delamination. Furthermore, in Comparative Example 2-4, which employed a thermal imidization method, gel defects were less likely to occur, but the warping of the laminate and the resin layer after delamination were more pronounced.

[0253] In Comparative Example 2-2, where the same polyamic acid solution as in Example 2-4 was used and a reaction accelerator was mixed and used, an increase in gel defects was observed, and the warpage of the laminate and the warpage of the resin layer after peeling increased.

[0254] Further, in Comparative Example 2-3 where the same polyamic acid solution as in Example 2-3 was used and thermal imidization was performed, although gel defects were less likely to occur, the warpage of the laminate and the warpage of the resin layer after peeling were more prominent. In Comparative Example 2-5 where the same polyamic acid solution as in Example 2-5 was used, although gel defects were less likely to occur, the warpage of the laminate and the warpage of the resin layer after peeling were more prominent.

Industrial Applicability

[0255] According to the present invention, it is possible to provide a method for producing a polymer film that can suppress deterioration of physical properties and appearance due to gel defects and also reduce problems such as coloring of the polymer film and increase in peel strength, so that it has high industrial applicability.

[0256] According to the present invention, it is possible to provide a method for producing a laminate that can suppress gel defects and reduce the warpage of the laminate and the warpage of the resin layer after peeling, as well as a method for producing a flexible substrate using the same, so that it has high industrial applicability.

Explanation of Signs

[0257] 11 Surface plate 12 Specimen

Claims

1. A method for producing a polymer, comprising the steps of: coating a support with a solution containing a polymer precursor which is a precursor of polyimide; and chemically reacting the polymer precursor, A method for producing a polymer, wherein an imidation accelerator for promoting the chemical reaction of the polymer precursor is present on the surface of the support beforehand (except in the case where a polyimide resin precursor composition containing the imidation accelerator is present on the surface of the support beforehand).

2. A method for producing a polymer film, comprising the step of forming a polymer film on a support by the polymer production method described in claim 1.

3. A method for producing a polymer film according to claim 2, comprising the steps of: heating the applied solution to obtain a self-supporting polymer precursor film; and peeling the polymer precursor film from the support.

4. The method for producing a polymer film according to claim 3, wherein the peel strength between the support and the polymer precursor film is 0.001 N / cm or more and 0.9 N / cm or less.

5. The polymer film is a polyimide resin film, and the amount of the imidization accelerator present per unit area is 5 to 150 mg / m² per 1 μm thickness of the polyimide resin film. ２ A method for producing a polymer film according to any one of claims 2 to 4.

6. A method for producing a polymer film according to any one of claims 2 to 5, wherein the polymer film is a polyimide film and the solution of the polymer precursor is a polyamic acid solution.

7. A method for producing a polymer film according to any one of claims 2 to 6, wherein the polymer film is a transparent polyimide film.

8. A method for producing a laminate, comprising the step of obtaining a laminate having a resin layer containing a polymer on a support by the polymer production method described in claim 1.

9. The method for producing a laminate according to claim 8, wherein the chemical reaction is carried out under heating, and the amount of warping of the obtained laminate when heated at 300°C for 1 hour is 300 μm or less.

10. The method for manufacturing a laminate according to claim 8 or 9, wherein the laminate has a curvature of 1,000 μm or less of the resin layer peeled off from the support.

11. The resin layer contains a polyimide resin, and the amount of the imidization accelerator present per unit area is 5 to 150 mg / m² per 1 μm thickness of the resin layer. ２ A method for manufacturing a laminate according to any one of claims 8 to 10.

12. A method for producing a laminate according to any one of claims 8 to 11, wherein the polymer is a polyimide and the solution of the polymer precursor is a polyamic acid solution.

13. A functional layer formation step of forming a functional layer on the resin layer of the laminate obtained by the manufacturing method according to any one of claims 8 to 12, A separation step of peeling the resin layer from the support to obtain a flexible substrate having the functional layer on the resin layer, A method for manufacturing a flexible substrate, including the method described above.

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