TW201712059A - Method for manufacturing polyimide film which improves productivity and reduces cost by a time-reduction heat treatment step and avoiding the outcomes of bubbling and insufficient hardening - Google Patents

Abstract

The present invention provides a method for manufacturing a polyimide film, which improves productivity and reduces cost by a time-reduction heat treatment step. The method for manufacturing the polyimide film of the present invention is a method in which the heat treatment step is completed by coating a resin solution of a polyimide precursor or a polyimide on a substrate in such a manner that the thickness of the polyimide film becomes 50 [mu]m or less, and the polyimide film formed on the substrate does not have a poor appearance due to bubbles or bubble traces. It is characterized in that the polyimide film can be peeled off from the coated substrate, the polyimide film comprises a single or a plurality of polyimide layer, and the polyimide which constitutes the main polyimide layer comprises 70 mol% or more of structural unit represented by the general formula (1), and the time for heat treatment is less than 10 minutes.

Description

Method for producing polyimine film

The present invention relates to a method for producing a polyimide film. In particular, the present invention relates to a flexible element for use as a liquid crystal display device, an organic electroluminescence (EL) display device, and a touch panel. A method for producing a polyimide film.

A large-sized display such as a television set, or an organic EL device used in various display applications such as a small-sized display such as a mobile phone, a personal computer, or a smart phone, usually forms a thin film transistor on a glass substrate as a supporting substrate (hereinafter, A TFT (Thin Film Transistor) is formed by sequentially forming an electrode, a light-emitting layer, and an electrode, and finally sealing it by a glass substrate or a multilayer film. In the configuration of the organic EL device, a bottom light-emitting structure that extracts light from the glass substrate side as a support substrate and a top light-emitting structure that extracts light from the side opposite to the glass substrate as the support substrate are used depending on the application. Further, in terms of structure, a structure in which external light directly passes can also be used. Therefore, a transparent structure in which an electronic component such as a TFT can be seen from the outside is also proposed. Both can be achieved by the selection of electrodes or substrate materials having transparency.

In addition, the support substrate of the organic EL device is replaced with a resin from the previous glass substrate, whereby thinness, light weight, and flexibility can be achieved, and the use of the organic EL device can be further expanded. However, compared with glass, resin is generally inferior in dimensional stability, transparency, heat resistance, moisture resistance, gas barrier property, and the like, and various studies are being conducted.

For example, Patent Document 1 discloses that a fluorine-containing polyimine composition obtained by introducing a fluorinated alkyl group into an acid anhydride and a diamine has a low dielectric constant, a low water absorption rate, and a low thermal expansion property, and can be applied to printing. A material for a plate or an optical waveguide.

For example, Patent Document 2 discloses a polyimine which is useful as a plastic substrate for a flexible display and a precursor thereof, and reports on the use of a tetracarboxylic acid having an alicyclic structure such as cyclohexylphenyltetracarboxylic acid and various The polyimine which is obtained by reacting a diamine is excellent in transparency.

In Patent Document 1 and Patent Document 2, a stable polyimine precursor solution is obtained from tetracarboxylic dianhydride and a diamine, and then coated on a substrate such as glass and heat-treated to obtain a polyimine. membrane. However, in order to obtain a polyimide film which has been completely imidized, it is necessary to slowly raise the temperature and carry out a plurality of heat treatments for several hours. When the heat treatment is to be completed in a short time, bubbles are contained in the polyimide film, or the bubble marks remain, and characteristics such as appearance and mechanical strength are deteriorated.

Further, Patent Document 3 discloses a method for producing a laminated member in which a base film of the laminated member is provided with a polyamidene layer obtained by coating a polyamic acid solution on a support material and performing hydrazine imidization. After the functional layer is formed on the polyimine layer side, the support material is separated and removed by the interface between the polyimide layer and the support material, and the base film is thinned. However, in Patent Document 3, it is necessary to heat-dry at 130 ° C, and further heat-treat to 160 ° C to 360 ° C at a temperature increase rate of about 4 ° C / min to 20 ° C / min.

In addition to the above, attempts have been made to reduce the weight of the flexible resin by supporting the substrate. For example, Non-Patent Document 1 and Non-Patent Document 2 propose a method for applying a highly transparent polyimide. An organic EL device for supporting a substrate. However, in the polyimide film described in these documents, a hardening reaction using heat treatment for several hours is also required. [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

[Non-Patent Document 1] S. An et al., "2.8-inch WQ VGA Flexible AMOLED Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates", SID 10 DIGEST, p706 (2010) [Non-Patent Document 2] Oishi et al., "Transparent PI for flexible display" for flexible displays, IDW '11 FLX2surasshuFMC4-1

[Problems to be Solved by the Invention] The time required to greatly shorten the heat treatment step for obtaining a polyimide film is strongly expected to contribute to productivity improvement and cost reduction. However, if the resin solution of the solvent-containing polyimine precursor or polyimine is to be dried in a short time, there is a problem in that foaming is caused by rapid evaporation of the volatile component. A bubble mark generated by the generation of bubbles or bubbles. Further, when the hydrazine imidization is carried out, the water vapor generated in the dehydration reaction in the hydrazine imidization step is rapidly generated, and similarly, foaming or bubble marks are generated, resulting in poor appearance, and The problem of the amination hardening reaction becomes insufficient. [Technical means to solve the problem]

Therefore, the inventors of the present invention have focused on the type and structure of the polyimide precursor or the polyimide, which is used for the reason that the foaming or hardening step is insufficient, and the thickness or heat treatment time to be applied. The present invention has been completed.

That is, the gist of the present invention is as follows. (1) A method for producing a polyimide film, which comprises applying a resin solution of a polyimide precursor or a polyimide pigment to a coating substrate such that a thickness of the polyimide film becomes 50 μm or less And a heat treatment, thereby forming a polyimide film having no appearance defect caused by bubbles or bubble marks on the coated substrate, characterized in that the polyimide film can be coated from The substrate is exfoliated, and the polyimide film comprises a single layer or a plurality of layers of polyimine, and the polyimine constituting the main polyimine layer is 70 mol% or more of the formula (1). The structural unit is represented, and the heat treatment time is within 10 minutes. [Chemical 1] [wherein Ar ₁ represents a tetravalent organic group having an aromatic ring, and Ar _{2 is a} divalent organic group represented by the following general formula (2) or (3). [Chemical 2] [Chemical 3] Here, R ₁ to R ₈ are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon group having 1 to 5 carbon atoms.

(2) The method for producing a polyimide film according to (1), wherein the resin solution is a polyimide precursor solution, and the heat treatment comprises a preheating step at 180 ° C to 220 ° C and exceeding A hardening step of 220 ° C and a maximum temperature of 320 ° C or more.

(3) The method for producing a polyimide film according to (2), wherein the holding time at 320 ° C in the hardening step is at least 1 minute.

(4) The method for producing a polyimide film according to (1) or (2), wherein the holding time in the preheating step at 180 ° C to 220 ° C is 0.5 minutes or more, the preheating step and hardening The total of the steps is 3 minutes or more.

(5) The method for producing a polyimide film according to any one of (1) to (4) characterized in that the water vapor transmission rate of the polyimide film is 10 g/m ² /day ～ 70 g/m ² /day.

(6) The method for producing a polyimide film according to any one of (1) to (5), wherein R ₁ to R _{4 of the} formula (2) or R of the formula (3) At least one of ₁ to R ₈ is a fluorine atom or a fluorine-substituted hydrocarbon group.

(7) A method for producing a polyimine film having a functional layer, which comprises coating a polyimide solution of a polyimide or a polyimide film in such a manner that a thickness of the polyimide film becomes 50 μm or less After coating the substrate and completing the heat treatment, a polyimine film having no appearance defect caused by bubbles or bubble marks is formed on the coated substrate, and then a function is formed on the polyimide film. a method for producing a polyimide film with a functional layer, characterized in that the polyimide film is peeled off from a coated substrate, and the polyimide film comprises a single layer or a plurality of layers of polyimine. In the layer, the polyimine which constitutes the main polyimine layer is a structural unit represented by the above formula (1) having 70 mol% or more, and the heat treatment time is within 10 minutes. [Effects of the Invention]

According to the present invention, when a flexible element such as a liquid crystal display device, an organic EL display device, or a touch panel is manufactured using a polyimide film, the time of the heat treatment step in obtaining the polyimide film can be greatly shortened, and thus production Excellent, and can greatly contribute to manufacturing cost reduction.

In the method for producing a polyimide film of the present invention, a polyimide solution of a polyimide or a polyimide is coated on a coated substrate such that the thickness of the polyimide film becomes 50 μm or less. And the heat treatment is completed, whereby a polyimide film having no appearance defect caused by bubbles or bubble marks is formed on the coated substrate.

The diamine and the acid dianhydride which are the monomers of the polyimine precursor or the polyimine used in the present invention may be contained alone or in combination of a plurality of monomers.

The polyimine film of the present invention is preferably a polyimine containing a structural unit represented by the above formula (1). Alternatively, a copolymer having a plurality of monomers having a structural unit represented by the general formula (1) is preferably used, and more preferably 70% by mole or more, preferably 90% by mole to 100% by mole. (1) The polyimine resin of the structural unit represented is preferred.

When the polyimide film comprises a plurality of layers of polyimine, as long as the main polyimide layer satisfies the above, it contains 70 mol% or more, preferably 90 mol in all the polyimide layers. The structural unit represented by the general formula (1) is preferably from % to 100% by mole. Here, the main polyimine layer is preferably a layer which accounts for 50% or more of the thickness of all the polyimide layers.

In the formula (1), Ar ₂ is a divalent organic group represented by the above formula (2) or (3). In the general formula (2) or the general formula (3), R ₁ to R ₈ are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a carbon number. a fluorine-substituted hydrocarbon group of 1 to 5. The alkyl group having 1 to 5 carbon atoms and the alkoxy group having 1 to 5 carbon atoms are preferably a methyl group, an ethyl group, a methoxy group or an ethoxy group. The fluorine-substituted hydrocarbon group having 1 to 5 carbon atoms is preferably a fluorine-substituted alkyl group having 1 to 5 carbon atoms.

When either or both of Ar ₁ or Ar ₂ in the formula (1) has a fluorine atom or a fluorine-substituted hydrocarbon group, the transparency of the obtained polyimide film is improved. In a preferred embodiment, in the above formula (2), it is preferred that at least one of R ₁ to R ₄ is a fluorine atom or a fluorine-substituted hydrocarbon group, and in the above formula (3), R ₁ to R ₈ It is preferred that at least one of them is a fluorine atom or a fluorine-substituted hydrocarbon group.

Specific examples of R ₁ to R ₈ in the formula (2) or the formula (3) include -H, -CH ₃ , -OCH ₃ , -F, -CF ₃ and the like, and more preferably It is preferable that at least one of R ₁ to R ₈ is -F or -CF ₃ .

In the formula (1), Ar ₁ represents a tetravalent organic group having an aromatic ring. Specific examples of Ar ₁ include the following tetravalent acid anhydride residues. [Chemical 4]

Further, specific examples of Ar ₂ include the following diamine residues. [Chemical 5]

Particularly preferred Ar ₂ is represented by the following formula. [Chemical 6]

The polyimine film is obtained from the resin solution of the polyimine precursor or the polyimine used in the present invention, but the polyimine which constitutes the polyimide film is aggregated by the resin solution It is determined by a ruthenium imine precursor or a polyimine, and thus a polyimine precursor or a polyimide which is used as a raw material is understood by explaining a polyimine which constitutes a polyimide film.

Therefore, the polyimine which constitutes the polyimide film will be described. A preferred polyimine is a polyimine containing a structural unit of the following formula (4) and formula (5). Here, the ratio of the formula (4) to the formula (5) is (4) in terms of a molar ratio: (5) = 50: 50 to 100: 0, preferably (4): (5) = 70: 30 to 95. : 5, more preferably (4): (5) = 85: 15 to 95: 5. The constituent unit is contained in the polyimine in an amount of from 90 mol% to 100 mol%. [Chemistry 7] (4) [Chem. 8] (5)

Here, the structural unit of the above formula (4) is mainly effective for improving properties such as low thermal expansion property and high heat resistance, and the structural unit of the general formula (5) is effective for improving high transparency. The polyimine of such a preferred form does not exclude structural units other than the structural unit represented by the general formula (4) and the general formula (5) (hereinafter, also referred to as structural unit a and structural unit b, respectively). . However, it is preferable to contain a structural unit other than the structural unit a and the structural unit b in a range of less than 10% by mol, and most preferably a polyimine containing only the structural unit a and the structural unit b. A film is preferred.

The polyimide film formed on the coated substrate may be not only a single layer but also a layer containing a plurality of layers of polyimine. For example, a polyimide layer may be provided on the side of the coated substrate. The layer on the opposite side is a layer having a composition which is easily compatible with the functional layer, for the layer which is easily peeled off from the coated substrate. In this case, it is preferred that the main polyimine layer be a polyimine layer on the functional layer side.

The polyimine containing the structural unit represented by the general formula (1) may contain other structural units other than the polyimine. The structural unit is preferably less than 30 mol% of all structural units. On the other hand, there may be other polyimines which do not contain the structural unit represented by the general formula (1). The polyimine is converted to all structural units, and the other structural units are preferably less than 30 mol%.

With respect to other polyimine resins which do not contain the structural unit represented by the above formula (1), it can be selected from general anhydrides and diamines, but it is desirable to have a coefficient of thermal expansion of not more than 15 ppm/K. The acid anhydride and the diamine are selected, and if necessary, the thickness is adjusted or multi-layered, up to less than 30% by mole, preferably less than 10% by mole.

Examples of the acid anhydride which can be preferably used in the present invention include pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and 1,4-cyclohexanedicarboxylic acid. 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenyl) Hexafluoropropane dianhydride and the like. Further, examples of the diamine include 4,4'-diaminodiphenylphosphonium, trans-1,4-diaminocyclohexane, 4,4'-diaminocyclohexylmethane, and 2,2'- Bis(4-aminocyclohexyl)-hexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-diaminobicyclohexane, and the like. When the polyimine containing the structural unit represented by the general formula (1) contains other structural units other than the structural unit, the acid anhydride and the diamine which provide the other structural unit are preferably the same as described above.

The polyimine precursor or polyimine used in the present invention can be produced by polymerizing a diamine as a raw material and an acid anhydride in the presence of a solvent to prepare a polyimide precursor resin. Or, by subsequent heat treatment, hydrazine imidization is carried out to prepare a resin solution. The molecular weight of the polyimine precursor or polyimine can be controlled mainly by changing the molar ratio of the diamine as the starting material to the anhydride, but usually the molar ratio is equimolar (1:1).

As a method for producing a resin solution of the polyimine precursor or polyimine, for example, after dissolving a diamine in an organic solvent, acid dianhydride is added to the solution to produce a polyimide precursor. Polylysine. Examples of the organic solvent include dimethylacetamide, dimethylformamide, n-methylpyrrolidone, 2-butanone, diglyme, xylene, and the like, and one of the organic solvents, or Use two or more. Further, if necessary, ruthenium imidization is carried out and dissolved in a solvent to prepare a resin solution of polyimine. The step of hydrazine imidization can be carried out by thermal hydrazylation caused by heating and dehydration.

The resin solution of the polyimine precursor or the polyimine is applied onto the coated substrate so that the thickness of the polyimide film becomes 50 μm or less. The coating is performed by casting the resin solution onto a coated substrate such as a metal roll, and heating and drying the coated substrate to form a self-supporting gel film, and then coating the substrate. The method of obtaining a polyimide film by further heating at a high temperature while holding it by a tenter or the like is excellent in productivity, and is most widely carried out industrially.

Further, as another method, for example, a method in which the resin solution is cast-coated on an arbitrary coating substrate such as a glass plate or a copper foil by an applicator, pre-dried, and further, in order to remove the solvent and bismuth, is preferably used. The heat treatment is carried out by imidization, and then the coated substrate is removed by peeling, etching or the like. When the resin solution is cast coated on the coated substrate, the viscosity of the resin solution is preferably in the range of 500 cps to 70,000 cps. Further, the surface of the coated substrate which is the coated surface of the resin solution may be subjected to a surface treatment and then applied. When the substrate is coated with a glass plate or a copper foil or the like, the thickness thereof can be arbitrarily set. In consideration of the action or the windability of the coating substrate, for example, a thickness of 100 μm to 700 μm can be exemplified, but it is not particularly limited. However, it is desirable that the polyimide layer becomes thinner than the coated substrate. Further, as the coating substrate, a polyimide film can also be used.

The method of applying a resin solution such as a polyimide precursor to the coating substrate is not particularly limited, and a known method can be applied as long as a predetermined thickness precision can be obtained. For example, a spin coater, a spray coater, or a rod can be applied. A coater, or a method of extruding from a slit nozzle. In general, it is known that when a solution having a highly oriented resin having a rigid molecular chain is applied, a delay occurs due to shear stress generated during coating, but surprisingly, in the present invention, by based on a short time The coating method of heat treatment and uniform orientation does not affect the retardation. Therefore, any coating method in which the thickness precision and productivity of the polyimide film are coexisting can be selected.

Needless to say, the thinner the film thickness of the polyimide film, the more easily the solvent or the water vapor is detached. Therefore, the film thickness of the polyimide film is preferably as small as possible, as long as the film thickness is maintained as the strength of the polyimide film. In order to complete the heat treatment step in a short time in the present invention, it is necessary to be 50 μm or less. However, in consideration of maintaining the minimum strength as the polyimide film, a film thickness of 5 μm or more is preferable. More preferably, it is 10 μm to 30 μm. The film thickness after the heat treatment of the polyimide film can be arbitrarily set by adjusting the thickness of the coating film in consideration of film thinning (reduction in film thickness) caused by solid content concentration or hardening shrinkage of the resin solution. .

From the viewpoint of uniformly controlling the film thickness of the film at the time of coating, when the degree of polymerization of the polyimide precursor and the polyimine used to form the polyimide film is represented by the viscosity range of the resin solution The solution viscosity is preferably in the range of 500 cP to 200,000 cP, more preferably in the range of 1000 cP to 100,000 cP.

The resin solution of the polyimine precursor or the polyimine is applied onto the coated substrate, and then dried and heat-treated. Most of the drying is preferably less than 180 ° C, and the heat treatment is carried out at 180 ° C or higher. In the heat treatment at 180 ° C or higher, the removal of the residual solvent and the ruthenium imidation occur. However, if the solvent is removed or the ruthenium is simultaneously concentrated, the generation of bubbles or the like occurs, so that it is applied to 180 ° C to 220 ° C. After the preheating step, it is preferred to impart to the main heating step at a temperature of more than 220 ° C which is advantageous for the heat treatment of the ruthenium imide of the polyimide precursor or the heat treatment of the polyimide. The main heating step is also referred to as a hardening step.

In the present invention, when the polyimine precursor resin solution is subjected to heat treatment, heat drying, pre-drying, and heat treatment for removing the solvent are used as a preheating step, which is used at a high temperature for hydrazine imidization. The heat treatment is set as the main heating step. In the present invention, these preheating steps and main heating steps are combined as a heat treatment step, but the total time (hereinafter, also referred to as heat treatment time) of these heat treatment steps is within 10 minutes. By setting the heat treatment time to within 10 minutes, in addition to contributing to improvement in productivity and suppression of total cost, it is possible to suppress excessive decrease in coefficient of thermal expansion (CTE). Further, when it is desired to suppress foaming as much as possible and completely terminate the oxime imidization, the heat treatment time is preferably 2 minutes or longer, more preferably 3 minutes or longer. In the preheating step, it was confirmed that the solvent was kept at 180 ° C to 220 ° C for 0.5 minutes or more, and the solvent was substantially completely removed. In the main heating step, it was confirmed that it was kept for 1 minute in a temperature range of 320 ° C or higher. , then the imidization is completed. Further, in the preheating step, in order to suppress foaming, it is preferable to carry out heat treatment at 180 ° C to 220 ° C. However, a step of raising the temperature at a low temperature of not more than 180 ° C may be additionally provided before this. Further, from the viewpoint of productivity of the polyimide film, the preheating step is preferably 5 minutes or shorter.

Further, when the polyimine resin solution is subjected to a heat treatment, although the imidization is not required, if only the preheating is performed, the solvent remains, and the flexibility of the polyimide film of the present invention is applied. In the element, since the solvent is required to be reduced to the ppm level, the main heating step using high-temperature heating is required in the same manner as in the case of heat-treating the polyimide film of the polyimide precursor.

Although the reason why the heat treatment can be performed in a short time is not necessarily clarified, it is presumed that the polyimine is a linear polyimine which is hard and is considered to be a bulky structure, and is The thinness to a certain degree of film shape helps to complete the removal of the solvent and the oxime imidization reaction in a very short time.

The physical property index for completing the removal of the solvent or the quinone imidization reaction in a short period of time is exemplified by the water vapor transmission rate of the polyimide film. This is expected to be easy to remove the solvent as an indicator of the ease of detachment of water vapor generated in the oxime imidization reaction, and if it is within a certain range, foaming does not occur. At present, the range of the water vapor transmission rate estimated from the experimentally confirmed structure is preferably 1 g/m ² /day to 100 g/m ² /day, more preferably 10 g/m ² /day to 70 g/m ^{2 .} /day, particularly preferably 20 g/m ² /day to 60 g/m ² /day. When the amount is less than the above range, the volatile component such as a solvent is cured before being removed from the film during the imidization, and it is likely to cause foaming. If it is larger than this range, the gas barrier property is low, and therefore, it is used as a liquid crystal display device or In the case of a flexible element such as an organic EL display device or a touch panel, a gas barrier film is required, which causes a decrease in productivity and an increase in cost due to the addition of steps.

Further, in the present invention, a resin solution of a polyimine precursor or a polyimide may be applied onto a coating substrate, and after heat treatment, a component or a touch for a display device is formed on the polyimide film. A functional layer such as a conductive layer for a panel is used to produce a polyimide film having a functional layer. Further, the polyimide film having a functional layer can be widely provided to various flexible member applications by suitably peeling the coated substrate from the polyimide film. Therefore, the coated substrate and the polyimide film are formed with peelable adhesive strength. On the other hand, since a functional layer such as a display element or a conductive layer is formed in a state in which a polyimide film is present on the coated substrate as described above, it is preferable that the layer is not peeled off in the manufacturing step. Bond strength. The adhesive strength of the coated substrate and the polyimide film in this case is from 0.1 N/m to 100 N/m, preferably from 1 N/m to 50 N/m.

As a method of peeling the polyimide film from the coating substrate, a method of physically peeling off using a jig or the like may be used, but a laser peeling using an absorption wavelength of 300 nm to 400 nm using polyimine may also be used. (Laser lift-off) method. In this case, a well-known laser can be used for the laser used.

The polyimide film produced by the present invention has a coefficient of thermal expansion of 15 ppm/K or less, and the polyimide film may be a layer containing a plurality of layers of polyimine. Further, the polyimine having the structural unit represented by the above formula (1) is preferably used as a flexible member, and has sufficient self-supporting property and strength, and preferably has an elastic modulus of about 5 GPa to 10 GPa. Have a relatively hard nature.

The polyimide film produced by the present invention is a person who does not have an appearance defect caused by bubbles or bubble marks. Here, the appearance defect is qualified in the visual inspection described in the examples.

When the polyimide film produced by the present invention is used for applications requiring transparency such as a touch panel or a bottom emission type organic EL display element, the transmittance in the thickness actually used is only 440. In the wavelength region of nm to 780 nm, it may be 80% or more. When forming a film, it is preferable to form a polyimide having a transmittance of 80% or more in a wavelength region of 440 nm to 780 nm. Such a polyimine is a polyimine having a structural unit represented by the formula (4) and the formula (5) and fixed above.

In order to use the polyimide film produced by the present invention for a touch panel or a bottom emission type organic EL display element as described above, a functional layer as described below is formed on a polyimide film. . Hereinafter, a specific embodiment in which a functional layer is further formed on a polyimide film will be described in detail.

(Production of Transparent Conductive Film) As shown in FIG. 2, the transparent conductive layer 3 is laminated on a long roll-shaped polyimide film having the polyimide layer 2 on the coated substrate 1, whereby Transparent conductive film. That is, in this case, the transparent conductive layer corresponds to the functional layer 3. When a transparent conductive film is obtained, for example, a polyimide film containing a polyimide having sufficient heat resistance as a coating substrate 1 is formed on the coated substrate 1 by the heat treatment of the present invention. The amine layer (polyimine film) 2 is prepared to be wound into a roll-shaped long coated polyimide substrate.

The coated polyimide substrate 10 was placed in a roll-to-roll apparatus as shown in FIG. As shown in FIG. 1, the polyimide film 10 with a coating substrate is held on the take-up side roll mechanism 14, the feed mechanism 12, the take-up mechanism 13, and the take-up side roll mechanism 15. The transparent conductive layer is laminated on the surface of the polyimide layer 2 of the polyimide substrate 10 with a coating substrate which is extracted in the longitudinal direction by a vapor deposition method or the like in the step processing portion 11. In this case, in the case where a vacuum environment is required in order to laminate the transparent conductive layer, the entire roll-to-roll apparatus may be placed in a vacuum chamber to perform a process. After the transparent conductive layer is formed, it can be thinned by separating the interface between the coated substrate and the polyimide layer (polyimine film) 2.

However, if Indium Tin Oxide (ITO) is used as the transparent conductive layer, it is amorphous at the time of vapor deposition on the polyimide film 10 with the coated substrate, and its resistance value is high. . For example, when a transparent conductive film is applied to a touch panel, low resistance is required. Therefore, after the electrode pattern for the touch panel is patterned, annealing is performed at about 200° C. to 300° C. to reduce the resistance value. However, if the polyimide film is as in the present embodiment, The annealing temperature has sufficient heat resistance, and the annealing can be performed to sufficiently reduce the resistance.

When it is considered to supply a transparent conductive film to a touch panel or the like, it is preferable to make the thickness as thin as possible. However, if the film having a thickness of 50 μm is applied to the roll-to-roll device alone, the difficulty in handling or the elongation of the film during the transfer becomes a problem. Therefore, as in the present embodiment, the coated substrate and the polyimide are not used. When the amine layer is separated and treated, the transparent conductive film having a thickness of about 10 μm or less (the thickness of the transparent conductive layer is about 100 nm) can be produced industrially with good productivity.

(Production of Gas Barrier Film) For example, when moisture or oxygen enters the organic EL light-emitting layer of the organic EL device, deterioration of characteristics is caused. Therefore, a gas barrier layer for preventing entry of moisture or oxygen is indispensable. Therefore, in the process processing unit 11, for example, ruthenium oxide, aluminum oxide, ruthenium carbide, ruthenium oxycarbide, ruthenium carbide, ruthenium nitride, and nitridation can be formed by a chemical vapor deposition (CVD) method. A thin film-formed gas barrier film is obtained in the same manner as in the case of the transparent conductive film, except that an inorganic oxide film such as ruthenium oxide is formed as a functional layer.

However, if the difference between the coefficient of thermal expansion (CTE) of the gas barrier layer containing the inorganic oxide film and the CTE of the polyimide film containing the polyimide layer 2 becomes large, dimensional stability is deteriorated in addition to curling. Or, depending on the situation, cracks may occur. In particular, when manufacturing a large-area film, the problem of warpage becomes more remarkable. Therefore, as long as the polyimine layer 2 selected from the appropriate acid anhydride and diamine is formed as described above, the CTE can be made 15 ppm/K or less, and the CTE which is usually 10 ppm/K or less can be reduced. The difference in the inorganic oxide film thus eliminates the occurrence of the above-described undesirable conditions. Further, the gas barrier layer may be formed of an inorganic film as described above, or may be formed by including two or more kinds.

(Manufacturing of Thin Film Transistor) First, a thin film transistor (TFT) is roughly classified into an amorphous germanium TFT (a-Si TFT) and a polycrystalline germanium TFT, and in a polycrystalline germanium TFT, a low temperature polycrystalline germanium TFT (LTPS) capable of lowering a process temperature can be realized. -TFT) is becoming mainstream. Hereinafter, a method of obtaining an a-Si TFT of a bottom gate structure when a thin film transistor (TFT) for a substrate or the like of a liquid crystal display device is obtained will be described.

In order to prevent intrusion of oxygen or water vapor from the outside, a gas barrier layer is provided in advance on the polyimide film 10 with a coating substrate in the same manner as in the method for producing the gas barrier film. Next, a film is formed using a material that forms a gate electrode and wiring. As the film forming material, an Al-based material is mainly used, and lamination is performed by a method such as sputtering. After the film formation, the pattern of the gate and the wiring is transferred in the photolithography step, and is formed (patterned) into a predetermined shape by an etching process.

Then, a gate insulating film (SiN, SiO ₂ or the like) and a semiconductor layer (a-Si) are formed into a film by a method such as CVD, and formed into a predetermined shape. In the following, the processing steps such as the film formation step, the photolithography step, and the etching step can be repeated in the same manner, and the drain wiring, the source electrode, the interlayer insulating film, and the like are formed to obtain an a-Si TFT. Further, when an a-Si TFT as described above is to be obtained, the process treating portions 11 for various process processes can be horizontally arranged, and the polyimide film 10 with a coated substrate can be continuously subjected to continuous processing. The treatment may be carried out by re-extracting the temporarily taken-up polyimide film by a roll-to-roll method and dividing the process into several steps.

(Manufacturing of Organic EL Display Device) For example, when an organic EL display device having a bottom emission structure is to be obtained, first, on the side of the polyimide layer 2 with the polyimide substrate 10 coated with the substrate, The method is provided in the same manner as the gas barrier layer, and is configured to prevent moisture or oxygen from permeable to moisture. Next, a circuit constituent layer containing the thin film transistor (TFT) is still formed on the upper surface of the gas barrier layer. In this case, the LTPS-TFT is mainly selected as the thin film transistor. In the circuit constituent layer 3, an anode electrode including a transparent conductive film of ITO is formed in each region of the pixel region which is arranged in a matrix on the upper surface thereof. Further, an organic EL light-emitting layer is formed on the upper surface of the anode electrode, and a cathode electrode is formed on the upper surface of the light-emitting layer. The cathode electrode is formed in common in each pixel region. Further, a gas barrier layer is formed again so as to cover the surface of the cathode electrode, and a sealing substrate is provided on the outermost surface in order to protect the surface. It is preferable that a gas barrier layer that blocks moisture or oxygen permeation is laminated on the surface on the cathode electrode side of the sealing substrate.

As described above, in the organic EL display device, the polyimide film of the polyimide substrate 10 coated with the substrate is usually formed into a film in the above-described order, and finally sealed with a sealing substrate. Further, the organic EL light-emitting layer is formed of a multilayer film (positive electrode-light-emitting layer-anode electrode) such as a hole injection layer-hole transport layer-light-emitting layer-electron transport layer, and in particular, the organic EL light-emitting layer may be due to moisture or oxygen. On the other hand, it is formed by vacuum evaporation, and usually includes electrode formation and continuous formation in a vacuum.

(Manufacturing of Organic EL Illumination Device) When organic EL illumination is to be obtained, the functional layer is generally a bottom emission structure other than the TFT layer in the organic EL display device. Here, the anode electrode is usually a transparent electrode such as ITO, and the electrode resistance is a low resistance to a high temperature treatment. As described above, in the case of ITO, heat treatment is usually performed at a temperature of about 200 ° C to 300 ° C. Furthermore, organic EL illumination tends to be large, and the resistance value of the ITO electrode is becoming insufficient, and various alternative electrode materials are being explored. In this case, the temperature of the annealing treatment is likely to be higher than the temperature of 200 ° C to 300 ° C. However, if the polyimide film of the present invention has sufficient heat resistance, various alternatives can be dealt with. Electrode material.

(Manufacturing of Other Functional Layers) In addition to the above-described examples, for example, in addition to electronic paper or a touch panel, in order to obtain a vapor deposition mask, a wafer-level package (Fan-out Wafer Level Packaging, FOWLP) substrate, etc. As long as the desired various functional layers are formed on the polyimide film 10 with the coated substrate, the coated substrate is separated and removed by the interface of the polyimide layer 2 and the coated substrate. When the laminated member which is thinned is formed, it can be made thinner and lighter than the former. [Examples]

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited by the scope of the following examples.

The following is a brief description of the monomer or solvent in the case of synthesizing polyimine, and the measurement methods and conditions of various physical properties in the examples. TFMD: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl PMDA: pyromellitic dianhydride DMAc: N,N-dimethylacetamide 6FDA: 2,2' - bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

(Coefficient of thermal expansion: CTE) For a polyimide film of 3 mm × 15 mm size, a thermodynamic analysis (TMA) device was used to apply a load of 5.0 g on one side at a fixed heating rate (20 ° C/min). The tensile test was carried out in a temperature range of 30 ° C to 260 ° C, and the coefficient of thermal expansion (ppm / K) was measured from the amount of elongation of the polyimide film with respect to temperature.

(Stretching strength) A Strograph R-1 manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, and the film was cut into a strip having a width of 20 mm at 10 mm/min until it was broken. The tensile strength is determined by dividing the maximum point load by the cross-sectional area.

(Tear strength) A light load tear tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, and the measurement was performed with a sample size of 63.5 × 50 (mm) and a slit length of 12.5 mm.

(醯i-imidation ratio) The fluorene imine film was measured by a one-time Attenuated Total Reflectance (ATR) method using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation). The infrared absorption spectrum was calculated based on the absorbance of C=O stretching of the quinone imine group derived from 1780 cm ^-1 based on the benzene ring absorber in the vicinity of 1015 cm ^-1 .

(Appearance inspection) The heat-treated polyimide film was visually observed to confirm the presence or absence of foaming. A foamer having a diameter of 30 μm or more was set to be good (passed).

(Coating) An applicator adjusted so that the in-plane variation of the thickness becomes 1 μm or less is used for the polyimide film after the heat treatment.

(Heat treatment) Using a forced convection type hot air oven equipped with a blower fan, heat treatment was started 1 hour after reaching a predetermined temperature. The material for the polyimide film obtained by coating the polyimine precursor or the polyimide resin solution on the coated substrate is located in the center of the hot air oven which blows the hot air most strongly, and does not hinder the circulation of the hot air. The method is set on a table made of stainless steel wire, and heat treatment is performed by setting a plurality of heating furnaces having different temperatures. In this case, the time of passing through the heating furnace became the heat treatment time, and the temperature deviation at the position of the material for the polyimide film was 2 °C.

Example 1 (polyimine A) was stirred in a 200 ml separable flask under a nitrogen stream while dissolving 12.55 g of TFMB in solvent DMAc. Then, 17.45 g of 6FDA was added to the solution. Thereafter, the solution was continuously stirred at room temperature for 5 hours to carry out polymerization, and kept for a day and night. It was confirmed that a viscous polyamine solution was obtained, and a high degree of polymerization of polyaminic acid A was produced. The polylysine solution obtained above was applied to a glass plate having a thickness of 0.5 mm by using an applicator so that the film thickness after the heat treatment became about 25 μm, and a nitrogen oven (oxygen concentration of 5% or less) was used. After performing 2 minutes and a half of auxiliary heating at 130 ° C and 160 ° C, respectively, the temperature was maintained at 180 ° C for 1 minute, at 220 ° C for 1 minute, at 280 ° C for 1 minute, and at 320 ° C for 1 minute. The laminate of the glass substrate and the polyimide film was obtained by holding at 360 ° C for 1 minute. The cutter was inserted into the interface between the glass substrate of the laminate and the polyimide film, and the polyimide film was peeled off from the glass substrate to obtain a polyimide film A. The results of various evaluations of the obtained polyimine film A are shown in Table 2.

(Polyimide B) 17.01 g of TFMB was dissolved in solvent DMAc while stirring under a nitrogen gas stream in a 200 ml separable flask. Then, 10.06 g of PMDA and 2.93 g of 6FDA were added to the solution. Thereafter, the solution was continuously stirred at room temperature for 5 hours to carry out polymerization, and kept for a day and night. It was confirmed that a viscous polyamine solution was obtained, and a polyglycolic acid B having a high degree of polymerization was produced. The film formation was carried out in the same manner as the polyamic acid A to obtain a polyimide film B. The results of various evaluations of the obtained polyimine film B are shown in Table 2.

In the same manner as in the first embodiment, the polyperuric acid A solution and the polyphosphinic acid B solution used in Example 1 were applied to a glass plate having a thickness of 0.5 mm, and the results were as shown in Table 1. The various heat treatment conditions shown in the film obtained a polyimide film. The various evaluation results of the obtained polyimide film were shown in Table 2.

Comparative Example 1 and Comparative Example 2 The polyplysine A solution used in Example 1 was applied onto a glass plate having a thickness of 0.5 mm in the same manner as in Example 1, and then obtained under the heat treatment conditions shown in Table 1. Polyimine film. Many bubbles were observed in the polyimide film obtained by the heat treatment conditions of Comparative Example 1, and volatile components such as a solvent were foamed. Further, the polyimide film obtained by the heat treatment conditions of Comparative Example 2 could not be peeled off from the glass substrate by the method of Example 1, and the evaluation of physical properties could not be performed.

In Comparative Example 3, a polyaminic acid B solution was applied to a glass plate having a thickness of 0.5 mm in the same manner as in Example 1, and then a polyimide film was obtained under the heat treatment conditions shown in Table 1. In the polyimide film obtained by the heat treatment conditions of Comparative Example 3, many bubbles were observed in the same manner as in Comparative Example 1, and volatile components such as a solvent were foamed.

Reference Example In the same manner as in Example 1, after the polyphthalic acid B solution used in Example 1 was applied onto a glass plate having a thickness of 0.5 mm, as previously known, the temperature was slowly raised from 130 ° C, and finally at 360. The heat treatment was carried out at ° C (heat treatment time was 35 minutes) to obtain a polyimide film. The various evaluation results of the obtained polyimide film were similarly shown in Table 2 for reference.

[Table 1]

[Table 2]

1‧‧‧ coated substrate
2‧‧‧polyimine layer
3‧‧‧ functional layer
10‧‧‧ Polyimide film with coated substrate
11‧‧‧Process Processing Department
12‧‧‧Send agency
13‧‧‧Winning agency
14‧‧‧Rolling mechanism
15‧‧‧Rolling mechanism on the take-up side

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of an apparatus for forming a functional layer on a polyimide film with a coated substrate comprising a coated substrate and a polyimide layer. 2 is a schematic cross-sectional view showing a step of peeling off a coated substrate from a polyimide film having a functional layer after forming a functional layer.

10‧‧‧ Polyimide film with coated substrate

11‧‧‧Process Processing Department

12‧‧‧Send agency

13‧‧‧Winning agency

14‧‧‧Rolling mechanism

15‧‧‧Rolling mechanism on the take-up side

Claims (6)

A method for producing a polyimide film, wherein a polyimide solution of a polyimide or a polyimide is coated on a coating substrate such that a thickness of the polyimide film becomes 50 μm or less A heat treatment is performed to thereby form a polyimide film having no appearance defect caused by bubbles or bubble marks on the coated substrate, characterized in that the polyimide film can be coated from the coated substrate The exfoliated, polyimine film comprises a single layer or a plurality of layers of polyimine, and the polyimine constituting the main polyimine layer is a structure represented by the formula (1) having 70 mol% or more. Unit, and the heat treatment time is within 10 minutes, In the formula, Ar ₁ represents a tetravalent organic group having an aromatic ring, and Ar _{2 is a} divalent organic group represented by the following general formula (2) or (3). Here, R ₁ to R ₈ are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon group having 1 to 5 carbon atoms. The method for producing a polyimide film according to claim 1, wherein the resin solution is a polyimide precursor solution, and the heat treatment comprises a preheating step at 180 ° C to 220 ° C and a temperature exceeding 220 ° C. And the highest temperature is a hardening step of 320 ° C or more. The method for producing a polyimide film according to claim 2, wherein the 320 ° C holding time in the hardening step is at least 1 minute. The method for producing a polyimide film according to the second or third aspect of the invention, wherein the holding time in the preheating step of 180 ° C to 220 ° C is 0.5 minutes or longer, and the preheating step and the hardening step are The total is more than 3 minutes. The method for producing a patented scope of the polyimide film of any of items 1 to item 4, wherein: R formula (2) R ₁ ~ R _4, or the general formula (3) ₁ to At least one of R ₈ is a fluorine atom or a fluorine-substituted hydrocarbon group. A method for producing a polyimine film having a functional layer, which comprises coating a resin solution of a polyimide precursor or a polyimide film in a coating film having a thickness of 50 μm or less. On the substrate, heat treatment is performed to form a polyimine film having no appearance defect caused by bubbles or bubble marks on the coated substrate, and then a functional layer is formed on the polyimide film. A method for producing a polyimide film with a functional layer, characterized in that the polyimide film is peeled off from the coated substrate, and the polyimide film comprises a single layer or a plurality of layers of polyimine. The polyimine of the main polyimine layer is a structural unit represented by the general formula (1) having 70 mol% or more, and the heat treatment time is within 10 minutes. In the formula, Ar ₁ represents a tetravalent organic group having an aromatic ring, and Ar _{2 is a} divalent organic group represented by the following general formula (2) or (3). Here, R ₁ to R ₈ are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon group having 1 to 5 carbon atoms.