JP7048367B2 - A coating liquid for forming a flattening film and a method for producing the same, a metal foil coil with a flattening film and a method for producing the same, and a ketone solvent containing silica fine particles used therein. - Google Patents

Description

The present invention relates to a flattening film forming coating liquid and a metal leaf coil with a flattening film applicable to a flexible substrate for an electronic device, and a silica fine particle-containing ketone solvent used therein.

Flexible substrates are required for electronic devices such as electronic paper, organic EL displays, organic EL lighting, and solar cells. Conventionally, these devices were made on a glass substrate, but if they are made on a flexible substrate, they will not break even if dropped, and new applications that take advantage of their light weight and flexibility will expand. The resin film being studied as a flexible substrate has a problem of poor heat resistance and poor dimensional stability, and a thin glass has a problem of being easily broken. The surface of the metal foil has rolling streaks and scratches, and the surface is so rough that it cannot be compared with glass. For this reason, it is important for the film covering the metal foil to flatten the surface of the metal foil to the same level as the glass substrate. This flattening film also imparts insulating properties to the metal foil.

The process temperature when manufacturing an electronic device varies depending on the type of electronic device and the constituent materials, but when manufacturing an amorphous silicon or LTPS (low-temperature verify silicon) TFT required for an organic EL display, the temperature is 300 to 400 ° C. The process temperature will be about the same. Therefore, the insulating film that covers the metal foil is also required to have heat resistance that can withstand up to 400 ° C.

Examples of the film material for coating the metal foil include an inorganic / organic hybrid material. Organic materials lack heat resistance. When coated with an organic material, the organic material coated with the organic solvent for cleaning swells in the cleaning / drying step of the metal leaf with a flattening film before the device is formed, or the moisture absorbed by the coated organic material during cleaning. It is not suitable because it is difficult to remove all the solvents and solvents by drying, and residual components may adversely affect the device. Inorganic materials are prone to cracks, and it is difficult to form a thick film that can cover rolling streaks and scratches on the surface of metal foil. Therefore, an inorganic / organic hybrid material having appropriate heat resistance and flexibility is suitable. An organically modified silica film is a typical example of an insulating film made of an inorganic / organic hybrid material. Since it contains an organic group, it is more flexible than an inorganic film and a thick film can be easily obtained. Since the main skeleton of the organically modified silica film is formed of an inorganic skeleton of Si—O, the heat resistance is determined by the decomposition temperature of the organic group modifying the main skeleton. If a methyl group or a phenyl group is selected as the organic group, heat resistance of about 400 ° C. can be ensured. In particular, the silica film modified with a phenyl group is resistant to hydrolysis due to the high hydrophobicity of the phenyl group, so that the Si—O main skeleton is not easily hydrolyzed even in high temperature and high humidity (for example, an environmental acceleration test at 85 ° C. and 85% RH). Excellent for. Therefore, as the substrate for the electronic device, a metal foil coated with a phenyl group-modified silica film is preferable.

When the device is formed on a flexible substrate, mass production can be performed at low cost by adopting the Roll to Roll process. For that purpose, a metal foil coil with a flattening film is required instead of a metal foil sheet on which a flattening film is formed. The metal foil coil is assumed to have a width of about 0.3 to 1.5 m and a length of about 50 to 2000 m. As one of the promising methods for coating such a metal foil coil with an inorganic / organic hybrid material, there is a method using a Roll to Roll film forming apparatus. FIG. 1 shows a schematic diagram of a typical Roll to Roll film forming apparatus. Normally, a Roll to Roll film forming device is a winding section for setting a solid metal foil coil to be deposited, a coating section for applying a coating liquid to the metal leaf coil, a drying section, a heat treatment section, and a deposited metal. It consists of a take-up part that winds up the foil coil. Since the device is generally manufactured on only one side of the substrate, the flattening film may be applied to one side as well. After applying the coating liquid, it may contain a large amount of solvent and moisture until it passes through the drying / heat treatment process, or the film may be inadequately hard and easily scratched. It is strongly desired that the transport roll does not touch the surface. Although the roll that touches the film-forming surface is colored in FIG. 1, tension can be applied to the base material by sandwiching the base material between the roll that touches the film surface and the roll that touches the opposite side of the film surface.

On the other hand, the drying / heat treatment furnace has a structure for transporting the metal foil coil flatly, and for a material having a long drying / heat treatment time, it is necessary to transport the metal foil very slowly or prepare a long furnace. However, in order to keep the film surface out of the roll in the furnace, long equipment with a furnace length of more than 10 m not only increases the manufacturing cost, but also makes the metal foil in the furnace even if the metal foil is distorted. Since the tension cannot be reapplied by sandwiching the metal, meandering may occur or the transportation may become unstable. As for the furnace length, even if it has a length of 10 m, the area where the heat treatment environment such as the maximum temperature and the atmosphere of the inert gas is secured is only a part of it, so it is short for industrial production with practical equipment. There is a demand for a material that can be heat-cured over time. The guideline is that the film cures within 2 minutes of heat treatment.

That is, in order to obtain a metal leaf coil with a flattening film that can be used as a flexible device substrate, the surface of the metal foil can be coated so as to have high smoothness similar to that of a glass substrate, and insulation is imparted for 2 minutes. There is a demand for an inorganic / organic hybrid film that can be cured within a range, particularly a silica film modified with a phenyl group.

Patent Document 1 discloses an insulating substrate for a solar cell and a stainless steel sheet coated with a material containing organoalkoxysilane as a method for producing the same. Insulation, heat resistance, and short-time curing are realized by forming a coating liquid by the so-called sol-gel method, but the coating liquid by the sol-gel method contains a large amount of solvent because it gels when the solid content concentration is increased. I'm out. The surface of the metal foil has many irregularities such as rolling streaks and scratches, and dents having a depth of several μm are usually found scattered on the surface. When a coating liquid having a low solid content concentration is applied to the surface of such a metal foil, the dents are alleviated after the solvent evaporates, but the metal foil surface is not completely flattened.

In Patent Document 2, the inventor of the present application has proposed a coating liquid for forming a flattening film by forming a phenylsilsesquioxane ladder polymer using phenyltrialkoxysilane and dissolving it in an aromatic hydrocarbon-based solvent. .. The coating liquid for forming a flattening film described in Patent Document 2 is prepared by adding phenyltrialkoxysilane, acetic acid, and organic tin as catalysts in an organic solvent, hydrocarbonizing with water, and then at a temperature of 160 ° C. or higher and 210 ° C. or lower. It is obtained by dissolving a phenylsilsesquioxane ladder polymer (hereinafter, also simply referred to as "ladder polymer") obtained by distilling off an organic solvent containing a product produced by hydrolysis under reduced pressure in an aromatic hydrocarbon solvent. ..

When the coating liquid for a flattening film of Patent Document 2 was applied to a base material and dried and heat-treated under the conditions corresponding to the organic group of the phenylsilsesquioxane ladder polymer, the base material was modified with an organic group. A flattening film of rudder polymer is obtained. Since this flattening film is formed from a precursor having a higher molecular weight than a normal sol-gel film, it has a feature that the film shrinks less during heat treatment and can be thickened. However, the hardness of the film was low and it was easy to get scratches.

In order to improve the flaw resistance of the flattening film on the substrate, it is common practice to add a filler to the film, and silica fine particles such as fumed silica and colloidal silica are used. However, the dry powder of silica fine particles tends to aggregate in a solvent. For example, when colloidal silica fine particles were dispersed in a ketone solvent and added to the coating liquid for forming a flattening film of Patent Document 2, the silica fine particles aggregated and it was difficult to form a film. In addition, cracks were also observed in the obtained flattening film.

Patent Document 3 suppresses the formation of aggregates of silica fine particles when forming a single-layer structure of silica fine particles on the base material by applying a silica fine particle dispersion liquid to the base material, and the base material is in a more uniform state. Discloses a fine particle dispersion liquid in which silica fine particles can be easily arranged. In Patent Document 3, in order to suppress the aggregation of monodisperse silica particles obtained by the sol-gel method (Staver method), the silica fine particles are hydrophobicized with a silane coupling agent to obtain a (meth) acrylic acid ester-based high molecular weight. It is dispersed in a dispersion medium containing molecules.

Patent Document 4 discloses that modified colloidal silica is used as an abrasive grain in a polishing composition for polishing an object to be polished such as a SiN wafer. Here, the raw colloidal silica is heated in the presence of a silane coupling agent having a functional group capable of chemically converting to a sulfonic acid group, and the modified colloidal silica in which the silane coupling agent is bonded to the surface of the silica particles is used. It suppresses aggregation of silicas.

The silica fine particles described in Patent Documents 3 and 4 are all dispersion liquids and polishing compositions containing the silica fine particles alone, and are fillers used by mixing the silica fine particles with a coating liquid containing components other than the silica fine particles. Not used as. Therefore, the cohesiveness in consideration of the components other than the silica fine particles has not been investigated.

In the prior art, the phenylsilsesquioxane ladder polymer resin described in Patent Document 2 is used as a matrix, and non-aggregated silica fine particles are contained as a filler, and a film having good scratch resistance of the silica fine particles has not been obtained.

Japanese Unexamined Patent Publication No. 11-40829 International Publication No. 2016/076399 Japanese Unexamined Patent Publication No. 2013-155096 International Publication No. 2016/117560

As described above, in the prior art, a film having good scratch resistance has not been obtained, in which the phenylsilsesquioxane ladder polymer resin described in Patent Document 2 is used as a matrix and non-aggregated silica fine particles are contained as a filler. ..

The present invention has been made to solve the above-mentioned problems, and an organic solvent including a solvent produced by adding phenyltrialkoxysilane, acetic acid, and organic tin to a ketone-based organic solvent, hydrolyzing, and then hydrolyzing is provided. A flattening film-forming coating solution in which the phenylsilsesquioxane ladder polymer resin obtained by distilling under reduced pressure is dissolved in a silica fine particle-containing ketone solvent, and a silica fine particle-containing ketone solvent used therein.

The present invention provides:
(1) In an alcohol solvent, 0.1 mol or more and 1 mol or less of acetic acid and 0.005 mol or more and 0.05 mol or less of organic tin are added as a catalyst to 1 mol of phenyltrialkoxysilane, and 2 mol or more and 4 mol or less. After hydrolysis with water, the organic solvent containing the product produced by hydrolysis was distilled off under reduced pressure at a temperature of 160 ° C. or higher and 210 ° C. or lower. Silica fine particles and silica produced by hydrolyzing alkoxysilane under a basic catalyst in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, the silica fine particle-containing ketone solvent containing a system solvent. A flattening film-forming coating solution containing a hydrolysis-condensation reaction product of an alkoxysilane that does not take the form of fine particles .
( 2 ) In an alcohol solvent, 0.1 mol or more and 1 mol or less of acetic acid and 0.005 mol or more and 0.05 mol or less of organic tin are added as a catalyst to 1 mol of phenyltrialkoxysilane, and 2 mol or more and 4 mol or less. After hydrolysis with water, the resin of the phenylsilsesquioxane ladder polymer obtained by distilling off the organic solvent containing the one produced by hydrolysis at a temperature of 160 ° C. or higher and 210 ° C. or lower under reduced pressure is obtained from a ketone containing silica fine particles. A method for producing a flattening film-forming coating solution dissolved in a system solvent, wherein the silica fine particle-containing ketone solvent is an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone under a basic catalyst of alkoxysilane. A method for producing a flattening film-forming coating liquid, which comprises silica fine particles and a hydrolysis-condensation reaction product of an alkoxysilane that does not take the form of silica fine particles, which is produced by hydrolysis in the above .
( 3 ) After applying the coating liquid according to (1 ) above to the metal foil coil, the surface of the metal foil coil is coated with a film thickness 2 by reflowing and film curing in a heat treatment process of 300 ° C. or higher and 450 ° C. or lower in an inert gas atmosphere. A metal leaf coil with a flattening film coated with a film of a phenylsilsesquioxane ladder polymer having a Ra of 0.0 μm or more and 5.0 μm or less and Ra of 30 nm or less in the direction perpendicular to rolling.
( 4 ) The metal foil coil according to ( 3 ) above, wherein the metal foil is a stainless steel foil.
( 5 ) The coating liquid according to (1 ) above is applied to a metal foil so as to have a film thickness of 2.0 μm or more and 5.0 μm or less, and is passed through a heat treatment furnace at 300 ° C. or more and 450 ° C. or less in an inert gas atmosphere. A method for manufacturing a metal leaf coil with a flattening film that is wound after reflowing and film curing.
( 6 ) The method for manufacturing a metal foil coil according to ( 5 ) above, wherein the metal foil is a stainless steel foil .
( 7 ) Hydrolysis of silica fine particles and alkoxysilanes that do not take the form of silica fine particles, which are produced by hydrolyzing alkoxysilane under a basic catalyst in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. A ketone solvent containing silica fine particles containing a condensation reaction product.
( 8 ) A step of mixing 0.5 to 85 mol of an organic solvent selected from methyl ethyl ketone, methyl isobutylken, and cyclohexanone with 1 mol of alkoxysilane, and stirring the mixture to prepare a solution 1.
A step of mixing 0.8 to 8 mol of water and 0.1 to 6 mol of a basic catalyst with respect to 1 mol of alkoxysilane to prepare a solution 2, and while stirring the solution 1, the solution 1 The method for producing a silica fine particle-containing ketone solvent according to ( 7 ) above, which comprises a step of dropping the entire amount of the solution 2 and further stirring after the dropping is completed.

According to the present invention, a film having high adhesion between the phenylsilsesquioxane ladder polymer resin and the silica fine particle filler and having high scratch resistance without cracks can be obtained even if the silica fine particle filling rate is high. Further provided, a flattening film forming coating liquid and a metal foil with a flattening film, which can be cured for a short time and have improved scratch resistance, can be applied to the Roll to Roll process.

The schematic diagram of the Roll to Roll film forming apparatus is shown. A photograph of the silica fine particle-containing ketone solvent used in the present invention dried on a slide glass at room temperature and observed with a scanning electron microscope is shown.

To obtain a metal leaf coil with a flattening film, from the viewpoint of flattening, the film reflows during the curing process to smooth out the unevenness of the surface of the metal foil, and within 2 minutes so that the film can be formed by the Roll to Roll process. In addition to the two points that it can be cured in the heat treatment time, it is important that the obtained film has high hardness and excellent scratch resistance.

The inventors have found a flattening film-forming coating film that can obtain a film having both the above two points and excellent scratch resistance with a film of a phenylsilsesquioxane ladder polymer having excellent heat resistance and moisture resistance. rice field. The flattening film-forming coating liquid of the present invention uses 0.1 mol or more and 1 mol or less of acetic acid and 0.005 mol or more and 0.05 mol or less of organic tin as catalysts with respect to 1 mol of phenyltrialkoxysilane in an alcohol solvent. In addition, after hydrolysis with 2 mol or more and 4 mol or less of water, the organic solvent containing the product produced by hydrolysis was distilled off under reduced pressure at a temperature of 160 ° C. or higher and 210 ° C. or lower to obtain a phenylsilsesquioxane ladder. It is a flattening film forming coating liquid in which a polymer resin is dissolved in a ketone solvent containing silica fine particles.

The inventors have studied various silica fine particles as a filler that does not easily aggregate, which is added to improve the flaw resistance of the flattening film on the substrate. As a result, in the method of producing silica fine particles from alkoxysilane by the sol-gel method, when alkoxysilane was hydrolyzed using an ammonia as a catalyst with a ketone solvent, silica fine particles of different sizes were precipitated and hydrolyzed. It has been found that an alkoxysilane monomer or oligomer is also produced, and by using this as a silica fine particle-containing ketone solvent for the resin of the phenylsilsesquioxane ladder polymer, a film having excellent scratch resistance can be obtained. I found.

The silica fine particle-containing ketone solvent that can be used in the present invention is a silica fine particle produced by hydrolyzing alkoxysilane under a basic catalyst in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. And a hydrolysis condensation reaction product of alkoxysilane which does not take the form of silica fine particles. FIG. 2 shows a photograph of the silica fine particle-containing ketone solvent used in the present invention observed with a scanning electron microscope. FIG. 2 is a micrograph of the silica fine particle-containing ketone solvent used in the present invention sucked up by a dropper and dried at room temperature on a slide glass. Silica particles having different sizes of about 0.9 μm and about 50 nm and a portion forming a film (shown as “film component” in FIG. 2) are observed. The portion forming the film is a hydrolysis condensation reaction product of alkoxysilane that does not take the form of silica fine particles.

The organic solvent used for producing the silica fine particle-containing ketone solvent is a ketone solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Even if it is a ketone solvent, acetone has a high affinity with water and is not suitable for producing a ketone solvent containing silica fine particles. A particularly preferred ketone solvent is cyclohexanone.

The ketone solvent preferably has a water solubility of 250 g / L or less at 20 ° C. Alkoxysilane usually mixes uniformly with a ketone solvent, but in a ketone solvent having low water solubility, water does not mix uniformly, so that the hydrolysis of alkoxysilane proceeds non-uniformly. Under a basic catalyst, the alkoxysilane molecule hydrolyzed in one place is selectively susceptible to the next hydrolysis. In a hydrophobic solvent, it is more stable if the hydrophilic groups are gathered together. Therefore, in the initial stage of hydrolysis, the dehydration condensation reaction proceeds, silica fine particles are formed, and the water generated in the dehydration reaction is the next hydrolysis reaction. Used in the growth of silica fine particles. At this time, the alkoxysilane molecule, which was hydrolyzed only in one place and not in the other part, exists as a monomer in the solvent as it is without being involved in the formation of silica fine particles, and the monomers are sequentially present with each other. Condensate to form an oligomer (a hydrolyzed condensation reaction product of alkoxysilane). When a basic catalyst is used in a ketone solvent having a low solubility in water as described above, relatively large particles of 100 nm or more and a monomer or an oligomer are produced at the initial stage of hydrolysis. When a certain amount of hydrolysis progresses, alcohol is obtained as a by-product of alkoxysilane, and it becomes a completely mixed solution consisting of ketone, alcohol, and water. Hydrolysis proceeds uniformly in the solvent, and the Stever method Similarly, small nanoparticles of less than 100 nm are generated depending on the amount of water added.

In the production of the silica fine particle-containing ketone solvent of the present invention, as a result of the hydrolysis reaction of alkoxysilane as described above, the hydrolysis condensation reaction product (monomer or oligomer) of the silica fine particles and the alkoxysilane which does not take the form of the silica fine particles). Coexist and generate. This monomer or oligomer provides the effect of enhancing the adhesion between the silica fine particles and the ladder polymer resin matrix.

The total solid content of the generated silica fine particles and the hydrolysis condensation reaction product of the alkoxysilane is usually 1 mass% or more and 20 mass% or less. When the total solid content concentration is less than 1 mass%, the effect of scratch resistance is less likely to be exhibited because the amount of silica fine particles and the hydrolysis condensation reaction product of alkoxysilane contained in the obtained flattening film is small. When the total solid content concentration exceeds 20 mass%, the storage stability of the silica fine particle-containing ketone solvent itself tends to deteriorate, and the proportion of silica fine particles in the flattening film increases, resulting in fine cracks in the film. , Leakage current tends to decrease.

The particle size distribution of the silica fine particles in the silica fine particle-containing ketone solvent used in the present invention is not monodisperse silica fine particles as obtained by the conventional sol-gel method represented by the Stever method, but is 10 nm to 100 nm. It has a range and a peak in the range of 100 nm to 1000 nm. Due to the existence of these two types, a group of particles having a large particle size and a group of particles having a small particle size, it is possible to increase the filling rate of the silica fine particle filler as compared with the monodisperse silica fine particles, which is obtained. It provides the effect of further enhancing the flaw resistance of the flattening film.
In the present invention, 1 ml of a ketone solvent containing silica fine particles is collected and dried on a slide glass, and 20 SEM photographs are taken. By creating a histogram on the horizontal axis with the diameter of particles that are similar to a sphere in increments of 25 nm such as ~ 50 nm, it is investigated whether or not the peak has a bimodal particle size distribution with two peaks.

The alkoxysilanes used in the production of the silica fine particle-containing ketone solvent are tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, trimethoxysilane, and tri. Ethoxysilane can be mentioned. A particularly preferred alkoxysilane is tetraethoxysilane. The catalyst used is a basic catalyst. Examples of the basic catalyst that can be used include aqueous ammonia, NaOH, and KOH. A particularly preferred basic catalyst is aqueous ammonia.

The silica fine particle-containing ketone solvent used in the present invention can be produced by the following steps.
For 1 mol of alkoxysilane, 0.5 to 85 mol of a ketone solvent is prepared and mixed with 1 mol of alkoxysilane by stirring. In another container, 0.8 to 8 mol of water and 0.1 to 6 mol of the basic catalyst are mixed with 1 mol of alkoxysilane to prepare a basic aqueous solution. A basic aqueous solution is added dropwise to the place where the alkoxysilane and the ketone solvent are stirred. After the completion of the dropping, the mixture is further stirred for 1 hour to obtain the silica fine particle-containing ketone solvent used in the present invention.

The resin of the phenylsilsesquioxane ladder polymer of the flattening film forming coating solution of the present invention contains 0.1 mol or more and 1 mol or less of acetic acid and 0.005 organic tin with respect to 1 mol of phenyltrialkoxysilane in an organic solvent. As a reaction by-product, an organic solvent used for hydrolysis of phenyltrialkoxysilane at a temperature of 160 ° C. or higher and 220 ° C. or lower after hydrolysis with 2 to 4 mol of water by adding mol or more and 0.05 mol or less as a catalyst. It is obtained by distilling off water and alcohol under reduced pressure.

The solution after hydrolysis was transparent with a viscosity of 1 to 2 mPa · s. The styrene-equivalent weight average molecular weight determined by GPC (gel permeation chromatography) was 300, indicating that it was a single molecule or a condensate of about two molecules of partially hydrolyzed phenyltrialkoxysilane. For vacuum distillation, the temperature is gradually raised from room temperature so that bumping does not occur. When the solvent of 600 ml of the hydrolyzed solution is distilled off under reduced pressure using an oil bath with a rotary evaporator, the solvent is kept at 50 ° C. for about 30 minutes until the solvent disappears, and then the temperature of the oil bath is raised to 130 ° C. to obtain the solvent. Hold for 30 minutes until no longer appears. As the temperature rises and the solvent is removed, the solid content concentration increases, the viscosity of the solid matter increases, and the spinnability is exhibited. The temperature of the oil bath can be raised to 160-210 ° C. and held for 30 minutes until the solvent disappears, and then held for another 15 minutes to completely remove the solvent. When the solvent is almost exhausted, the solid substance, that is, the resin showing spinnability, loses its fluidity at 160 to 210 ° C. The resin obtained at this time is a translucent to white solid at room temperature. After dissolving the resin in a ketone solvent containing silica fine particles, the styrene-equivalent weight average molecular weight determined by GPC was 5000 to 100,000.

As described above, the phenyltri according to the present invention showed spinnability, was dissolved in a solvent even though it had a high molecular weight, and showed a double peak derived from a siloxane bond near 1100 cm ^-1 in the infrared absorption spectrum. It is presumed that the resin made from ethoxysilane has a shape close to the ladder structure.

Since acetic acid is used as an acid catalyst in the present invention, the structure is similar to that of a ladder polymer, but a relatively large number of alkoxy groups and hydroxyl groups remain in the defective portion, and many reactive groups are contained. Therefore, between these reaction groups during heat treatment. It is considered that the condensation reaction proceeds and the film can be cured in a short time. Here, film hardening means that the pencil altitude of the film after heat treatment becomes 3H or higher, making it difficult for flaws to occur, and components that can cause leakage of the insulating film, such as the solvent and moisture in the film, volatilize, resulting in the insulating film. This means that the two conditions of forming an insulating film having a leakage current of 1E-6A / cm ² or less are satisfied. The leakage current of the insulating film is measured by applying a voltage of 100 V between the metal foil and the 1 cm square upper electrode formed on the film of the phenylsilsesquioxane ladder polymer film.

Further, in the present invention, the condensation reaction during the heat treatment is further promoted by the organic tin-derived Sn added as a catalyst, and the film can be cured in a short time capable of continuous heat treatment within 2 minutes at 300 to 450 ° C. ..

Hereinafter, the parameter conditions for obtaining the highly smoothed film of the present invention will be described. Unless otherwise specified, the number of moles is the amount per mole of phenyltrialkoxysilane.

The amount of acetic acid during the synthesis of the coating liquid has a great influence on the progress of hydrolysis of phenyltrialkoxysilane. When the amount of acetic acid is less than 0.1 mol, only a part of phenyltrialkoxysilane is hydrolyzed, so that the subsequent polycondensation reaction does not proceed easily, resulting in a low molecular weight resin. If the rudder polymer does not have a certain length, the entangled polymer will not be unwound by thermal vibration and exhibit reflowability, which is not suitable. When the amount is more than 1 mol, all the alkoxy groups of almost all phenyltrialkoxysilanes are hydrolyzed, so that the subsequent polycondensation reaction proceeds too rapidly and gelation occurs at the stage of hydrolysis before distillation under reduced pressure. Is not suitable because it occurs.

Organic tin is a catalyst that promotes the polycondensation reaction of phenyltrialkoxysilane, its hydrolysis condensation reaction product, and phenyl group-containing ladder polymer. When the amount of organic tin is less than 0.005 mol, the effect of promoting the condensation reaction of the ladder polymer during the heat treatment is insufficient, and it is not suitable because it cannot be cured for a short time. If the amount of organotin exceeds 0.05 mol, polycondensation of phenyltrialkoxysilane and its hydrolysis condensation reaction product proceeds too much, and gelation occurs at the stage of hydrolysis before distillation under reduced pressure, which is unsuitable.

If the amount of water used for hydrolysis is less than 2 mol, a large amount of alkoxy groups will remain in the resin, and a condensation reaction (ladder polymerization) will have to be performed during the heat treatment. Therefore, the heat treatment at 350 to 450 ° C. for 2 minutes is unsuitable because the heat treatment time is insufficient and the solvent and moisture remain on the film, resulting in poor insulation. If the amount of water exceeds 4 mol, hydrolysis will proceed rapidly, so a mesh structure will be formed at random rather than a ladder-like regular structure, and the resin will not dissolve, making it unsuitable because a coating solution cannot be prepared. Is. When the temperature at the time of distillation under reduced pressure is lower than 160 ° C., the condensation reaction of the resin is insufficient, so that the molecular weight distribution of the resin after dissolution may vary, and the low molecular weight components volatilize during film formation and become repellent. It is not suitable because it causes defects. If the temperature at the time of distillation under reduced pressure exceeds 210 ° C., the condensation reaction proceeds too much and the resin is difficult to dissolve in the ketone solvent, which is unsuitable. A more preferable temperature at the time of distillation under reduced pressure is 165 ° C. or higher and 180 ° C. or lower. The viscosity of the coating liquid can be adjusted by the amount ratio of the resin and the solvent, that is, the amount of solid content. The optimum viscosity and solid content amount depend on the coating method, but generally, if the solid content concentration is adjusted to 15 mass% or more and 40 mass% or less and the viscosity is adjusted to 3 mPa · s or more and 100 mPa · s or less, 2 to 5 μm. It can be applied uniformly with the same film thickness, and the storage stability of the coating liquid is also good.

Next, the metal leaf with a flattening film using the phenylsilsesquioxane ladder polymer film of the present invention will be described.

Since the metal leaf is thinned by rolling, streaks are recognized in the rolling direction. In addition, there are also flaws stretched in the rolling direction due to inclusions contained in the original molten metal, foreign matter caught in the rolling roll, and the like. The size of the flaw is often several tens of μm in width and one to several mm in length.

The surface roughness of the metal foil differs between the direction parallel to the rolling streaks and the direction perpendicular to the rolling streaks, and the vertical direction has a larger surface roughness. Therefore, for the purpose of improving the flatness of the metal foil by coating, it is necessary to pay attention to the vertical direction, which is the largest number of surface roughness. Specifically, the surface roughness is measured at 10 or more points with a measurement length of 1.25 mm by a stylus type roughness meter, perpendicular to the rolling direction of the metal foil coil, that is, in the width direction of the coil, and the average value is measured. Is adopted.

As a result of investigating in detail the relationship between the surface roughness of the metal foil with a flattening film and the characteristics of the organic EL element formed on it, it was found that the flatness of the film surface is important for reducing the leakage current of the element. rice field. Rolling of the surface of the metal foil with a flattening film and arithmetic in the vertical direction If the average roughness Ra is 30 nm or less, the leakage current of the organic EL light emitting element can be set to a practical level of 1E-4A / m ² or less. .. The leak current of the device is formed on the film of the phenylsilsesquioxane ladder polymer in the order of the lower electrode, the light emitting part, and the upper electrode of the device to form the device, and a voltage of 3 V is applied between the lower electrode and the upper electrode. Divide the current at the time by the element area to obtain it. Since the light emitting part is composed of a plurality of layers and the total layer thickness is about 100 to 150 nm, if the surface of the film is rough, a short distance between the lower electrode and the upper electrode is created, and the leakage current of the element increases. become. When Ra of the metal foil with a flattening film exceeds 30 nm, the element has a large leak current exceeding 1E-4A / m ² , which is unsuitable because the efficiency of the element is deteriorated or a short circuit occurs. A more preferable range of Ra is 20 nm or less, more preferably 15 nm or less, and a smaller leakage current can be obtained.

The surface roughness of the flattening film reflects the surface roughness of the metal foil to be coated. As for the surface roughness of the metal foil surface itself, Ra of 60 nm or less measured in the direction perpendicular to the rolling direction is a guideline for Ra of the flattening film to be 30 nm or less. However, even a relatively coarse metal foil tends to be easily flattened if a thick film of the phenylsilsesquioxane ladder polymer is formed. Examples of the metal foil include stainless steel foil, aluminum foil, titanium foil, plated steel foil, and copper foil. The thickness of the metal foil is preferably within a range that can be handled without breaking or wrinkling and does not impair flexibility, and is usually 30 μm or more and 150 μm or less easy to use, and a more preferable plate thickness is 35 μm or more and 80 μm or less.

The film thickness of the flattening film is 2 μm or more and 5 μm or less. If it is thinner than 2 μm, the unevenness of the metal foil itself cannot be completely covered. If it exceeds 5 μm, cracks are likely to occur in the film. Not only is it easy for cracks to form during film formation, but it is also easy for cracks to form in the film when the stainless steel foil coated with the flattening film is bent as a flexible substrate. It is more preferable that the film thickness is 2.5 μm or more and 4 μm or less from the viewpoint of uneven coating and crack prevention.

It is desirable that the flattening film contains Sn of 1 ppm or more and 5000 ppm or less. The concentration of Sn can be measured by SIMS (secondary ion mass spectrometry) analysis or X-ray fluorescence analysis. When the Sn concentration is less than 1 ppm, it may be difficult to continuously form a film on the coil by Roll to Roll because it is difficult to cure the film in a short time. When the Sn concentration exceeds 5000 ppm, the film becomes hard and cracks may easily occur when bent.

After the coating on the metal foil coil, the drying treatment is performed at a temperature of 20 ° C. or higher and 150 ° C. or lower. The purpose of the drying step is to remove the solvent and moisture contained in the applied film to form a dry film. If the drying temperature is higher than the resin synthesis temperature by distillation under reduced pressure, the rudder polymer forming the resin may soften, so it is desirable that the drying temperature is lower than the resin synthesis temperature. In the dry film, the rudder polymer is entangled and looks like a mesh structure and the film is cured, but when the movement of the molecule becomes active due to thermal vibration, the rudder polymer unravels and shows fluidity. become. In the heat treatment step, the rudder polymer forming the dry film is melt-softened, that is, reflowed to flatten the surface of the film, and the polymer is crosslinked following the reflow to form a three-dimensional network structure and cure the film. Two things are the purpose. Reflow is a phenomenon that occurs in a temperature range higher than the resin synthesis temperature by distilling under reduced pressure, and in a temperature range lower than the temperature at which three-dimensional cross-linking progresses and the film begins to harden. It is not necessary to take a special heat treatment process for reflow, and if the heat treatment is performed at 300 ° C. or higher and 450 ° C. or lower, reflow occurs in the process of raising the temperature to the heat treatment temperature, and the film hardening by crosslinking continues. In order to flatten the surface of the metal foil, it is effective to perform the heat treatment in a horizontal state as shown in FIG. Since film hardening is the formation of a network structure by a cross-linking reaction, once the film is hardened, it does not reflow again. If the heat treatment temperature is lower than 300 ° C, the cross-linking does not proceed sufficiently and reactive groups such as silanol groups remain in the film, resulting in insufficient insulation and moisture adsorbed on the silanol groups during the production of the organic device. Desorption is unsuitable because it adversely affects the element. If the heat treatment temperature is higher than 450 ° C., volume shrinkage occurs due to thermal decomposition of the phenyl group, and cracks are likely to occur, which is unsuitable. A more preferable heat treatment temperature is 360 ° C. or higher and 420 ° C. or lower.

Examples of the phenyltrialkoxysilane used in the present invention include phenyltrimethoxysilane, phenyltriethoxysilane, and phenyltripropoxysilane.

The organic solvent used for hydrolyzing phenyltrialkoxysilane is an alcohol solvent selected from methanol, ethanol, propanol and butanol.

Examples of the organic tin include dibutyltin diacetate, bis (acetoxydibutyltin) oxide, dibutyltin bisacetylacetonate, dibutyltin bismaleic acid monobutyl ester, dioctyl tin bismaleic acid monobutyl ester, and bis (lauroxydibutyltin) oxide. ..

The organic solvent including the one produced by hydrolysis distilled under reduced pressure includes alcohol produced by hydrolysis of phenyltrialkoxysilane in addition to the organic solvent used when hydrolyzing phenyltrialkoxysilane. Is done. It may also contain water produced by the condensation reaction of hydrolyzed phenyltrialkoxysilane.

Hydrochloric acid, nitric acid, and phosphoric acid were also examined as acid catalysts, but it was difficult to obtain a smooth film by making a ladder polymer with a high molecular weight as in the case of acetic acid and utilizing the reflow property. It is presumed that the reason for this is that the structure of the obtained ladder polymer is different in the case of acetic acid, which is a weak acid, and in the case of using hydrochloric acid, etc., because the hydrolysis proceeds more slowly in acetic acid.

To form a film on a metal foil coil, continuous film formation by Roll to Roll is performed. A general device configuration consists of a coil winding part, a coating part, a drying furnace, a heat treatment furnace, and a coil winding part. The faster the plate passing speed, the better the productivity, but it is generally about 1 mpm to 20 mpm. Examples of the coating method include coating with a microgravure roll, a gravure roll, etc., a slit coater, screen printing, and the like. If you want to apply on both sides of the stainless steel foil, you can also use a dip coat to form a film. Drying is carried out at 20 ° C. or higher and 150 ° C. or lower for about 0.5 to 2 minutes. The atmosphere in the furnace at the time of drying may be the atmosphere or the atmosphere of an inert gas such as nitrogen. The heat treatment is performed while flowing an inert gas so that the phenyl group is not easily decomposed by heat. In the case of a continuous film forming apparatus, a small amount of air is brought in when the substrate enters the heat treatment furnace, but the film of the phenylsilsesquioxane ladder polymer of the present invention is a film even if there is about 1% of air contamination. There is no effect on the characteristics. In the drying furnace and heat treatment furnace, design the equipment so that the roll does not hit the film surface on the device forming side. At the time of winding, a protective film may be attached to the film surface, or a slip sheet may be inserted to prevent scratches. Further, instead of continuously performing the drying and the heat treatment, the coil having the dried film may be wound once and only the heat treatment may be performed again. In this case, two types of equipment are required, one for producing a dry film and the other for heat treatment, but each has the advantage of being able to process at the optimum plate passing speed.

Although the manufacturing method for continuously forming a metal leaf coil with a flattening film of the present invention by Roll to Roll has been described above, the metal leaf coil with a flattening film of the present invention is not continuously coated but is coated by a batch method. Can also be manufactured.

Next, the present invention will be further described by way of examples. It goes without saying that the present invention is not limited to the examples presented herein.

Test 1
In Test 1, a flattening film-forming coating solution was prepared using various silica fine particle-containing ketone solvents for the phenylsilsesquioxane ladder polymer resin A falling within the scope of the present invention, and the obtained flatness was obtained. The chemical membrane was evaluated.

<Manufacturing of Resin A of Phenyl Sesquioxan Ladder Polymer>
Resin A of phenylsilsesquioxane ladder polymer was prepared by the following method. In ethanol, 0.3 mol of acetic acid and 0.012 mol of dibutyltin diacetate were added as catalysts to 1 mol of phenyltriethoxysilane, and the mixture was hydrolyzed with 3 mol of water. After refluxing under a nitrogen stream for 3 hours, the temperature was gradually raised using a rotary evaporator so as not to bump, and finally at 160 ° C., the organic solvent containing the product produced by hydrolysis was distilled off under reduced pressure to obtain a resin. rice field. The styrene-equivalent weight average molecular weight Mw determined by GPC was 150,000. Infrared absorption spectra showed two peaks at 1035 cm ^-1 and 1135 cm ^-1 , suggesting that it is a ladder polymer.

This resin A was dissolved in various silica fine particle-containing ketone solvents shown in Table 1 to prepare a coating liquid for forming a flattening film. Table 1 shows the amount (g) of alkoxysilane, which is the raw material of the silica fine particle-containing solvent used, the amount of basic catalyst (g), and the amount of water (g). The lower part of Table 1 shows the raw materials and the compounding ratio (mol) of the silica fine particle-containing solvent. The "amount of water (*)" here is the total number of moles of the amount of water in the aqueous ammonia solution and the amount of added water when the aqueous ammonia solution is used as the basic catalyst. While the silica fine particle-containing ketone solvent of Table 1 and the alkoxysilane are mixed and stirred, the mixed solution of the basic catalyst and water shown in Table 1 is added dropwise over about 1 hour, and another 1 hour after the addition is completed. Stirred.

1 ml of a ketone solvent containing silica fine particles was collected with a dropper and dried on silica glass for 24 hours at room temperature. 20 SEM photographs were taken at a magnification of 30,000 times, and image analysis type particle size distribution software Mac-View ver. A histogram of the particle size distribution was prepared using No. 4. The vertical axis is the number of particles, and the horizontal axis is the particle diameter from 0 to 1000 nm in 25 nm increments. The particles approximated a sphere. For those with a single particle size distribution, the average particle size was calculated using the entire distribution. In the case of a bimodal distribution with two peaks, the average particle size was calculated for each peak.
The coating liquid for forming a flattening film was prepared in a blending ratio such that the solid content concentration of the phenylsilsesquioxane ladder polymer, the silica fine particles, and the hydrolysis condensation reaction product of alkoxysilane was 30 mass%.

The coating liquid for forming a flattening film was formed on a 12 cm square metal foil with a spin coater. The film thickness was controlled by the rotation speed of the spin coater, and all the film thicknesses were 3 μm.
After drying at room temperature, the heat treatment was carried out in an infrared heating furnace in a nitrogen atmosphere at 400 ° C. in 0.5 minutes, and after holding for 2 minutes, the heater switch was turned off. In this case, the cooling time to 200 ° C. was 1 minute.

The hardness of the film after the heat treatment was evaluated by the pencil hardness according to JIS K5600. The pencil hardness was very good (⊚) for 7H or more, and good (◯) for less than 7H and 5H or more.

For the leakage current of the phenylsilsesquioxane ladder polymer film, a 1 cm square platinum upper electrode was formed on the phenylsilsesquioxane ladder polymer film using a mask with an ion coater to form an upper electrode. Using a stainless steel foil as a lower electrode, 100 V was applied between the upper and lower electrodes for measurement.

The repeated bending test was carried out 10,000 times with a surface spacing of 10 mm, a stroke of ± 60 mm, and 60 strokes per minute using a U-shaped folding tester manufactured by Yuasa System Equipment Co., Ltd. The leak current before and after the implementation was very good (⊚) if it was less than 1E-8A / cm2, and good (◯) if it was 1E-8A / cm or more and less than 1E-7.

In Comparative Example 1-1, toluene was used for producing the silica fine particle-containing solvent. Even if the production of alcohol due to the hydrolysis of alkoxysilane occurred, the mixing of toluene with water / alcohol did not proceed, and the gel was formed with phase separation, so the resin of the phenylsilsesquioxane ladder polymer was dissolved. I couldn't proceed to the process of letting it go.

In Comparative Example 1-2, an ethanol solvent was used in the same manner as in the usual Steber method. Therefore, the particle size distribution was one mountain with a peak at 35 nm, and no hydrolyzed monomer / oligomer of alkoxysilane was observed. Since no monomer / oligomer was formed, the adhesion between the particles and the phenylsilsesquioxane ladder polymer was low, and repeated bending tests caused fine cracks in the flattening film and increased the leakage current.

Comparative Example 1-3 is an example using acetone, which is a ketone that is miscible with water. Since water and acetone were mixed, non-uniform hydrolysis did not occur at the initial stage, hydrolyzed alkoxysilane monomers and oligomers were not produced, and the leakage current after repeated bending tests increased. Comparative Example 1-4 is an example using a commercially available high-concentration silica slurry, in which the amount of silica particles was too large and cracks occurred in the flattened film after drying.

Comparative Example 1-5 is an example using a silica slurry diluted to a low concentration. Since the monomer / oligomer of alkoxysilane was not contained, the leakage current after repeated bending tests increased.

Comparative Examples 1-6 to 1-8 are obtained by dissolving a phenylsilsesquioxane ladder polymer only in a solvent containing no silica particles. The pencil hardness of the film was low due to the absence of silica particles.

In Example 1-1, the leakage current was slightly higher because the solid content concentration of the silica fine particle-containing solvent was slightly higher. In Example 1-5, since the particle size distribution of the silica fine particles was one mountain, the packing rate of the particles could not be increased and the pencil hardness was slightly low. In Examples 1-6, the solid content concentration of the silica fine particle-containing solvent was slightly low, so that the pencil hardness was low. The other examples showed very good results.

Test 2
In Test 2, a flattening film-forming coating solution was prepared using various phenylsilsesquioxane ladder polymer resins against the silica fine particle-containing ketone solvent B falling within the scope of the present invention, and the obtained flatness was obtained. The chemical membrane was evaluated.

<Manufacturing of Ketone Solvent B Containing Silica Fine Particles>
5 mol of cyclohexanone and 1 mol of tetraethoxysilane were placed in a beaker and stirred with a magnetic stirrer. In another beaker, 28.39 g of a 30% aqueous ammonia solution and 1.73 g of water were mixed and added dropwise to a beaker containing cyclohexanone and tetraethoxysilane. A mixture of 28.39 g of a 30% aqueous ammonia solution and 1.73 g of water results in a mixture of 0.5 mol of ammonia and 1.2 mol of water. Stirring was continued with a magnetic stirrer during the dropping, and the mixture was stirred for 1 hour after the dropping was completed.

A coating liquid for forming a flattening film of a phenylsilsesquioxane ladder polymer was synthesized under various conditions. Hydrolysis was carried out by adding acetic acid, organotin and water to 1 mol of phenyltriethoxysilane in an ethanol solvent under the conditions shown in Table 2. After refluxing at 80 ° C. under a nitrogen stream for 5 hours, the solvent was distilled off under reduced pressure using a rotary evaporator. The temperature is gradually increased at the time of distilling under reduced pressure, and the maximum temperature at that time is shown in Table 2 as the distilling under reduced pressure. The total solid content concentration of the phenylsylsesquioxane ladder polymer obtained by distilling under reduced pressure, which is a combination of the phenylsylsesquioxane ladder polymer, the silica fine particles, and the monomer / oligomer in the silica fine particle-containing ketone solvent B, is 30 mass%. A coating liquid for forming a flattening film was prepared by dissolving the mixture so as to be.

The prepared coating liquid was applied with a spin coater on a stainless steel foil having a thickness of 50 μm finished with NSSC190SB and having a film thickness of 3 μm. Drying was carried out at 80 ° C. for 1 minute. The heat treatment is performed in an infrared heating furnace in a nitrogen atmosphere, the temperature is raised to the heat treatment temperature shown in Table 2 in 0.5 minutes, and the heater switch is turned on after holding for 1 minute, 2 minutes, 5 minutes, 15 minutes, and 30 minutes. It was turned off. In this case, the cooling time to 200 ° C. was 1 minute.

The film thickness of the phenylsilsesquioxane ladder polymer was measured by cutting a metal foil with a film and observing from a cross-sectional direction with a scanning electron microscope (SEM). When the average value of the surface roughness Ra of the flattening film measured 10 times with a stylus type roughness meter in the direction perpendicular to rolling is 30 nm or less ○, when it is over 15 nm, the flatness is good ○, when it is 15 nm or less Was judged to have very good flatness. When it exceeds 30 nm, it is regarded as unsuitable ×.

The hardness of the flattening film after the heat treatment was evaluated by the pencil hardness according to JIS K5600. The leak current of the phenylsilsesquioxane ladder polymer film is formed by forming a 1 cm square platinum upper electrode with an ion coater on the phenylsilsesquioxane ladder polymer film using a mask and using a stainless steel foil as the upper electrode. As a lower electrode, 100 V was applied between the upper and lower electrodes for measurement.

The shortest heat treatment holding time at which a pencil hardness of 5H or more and a leakage current of 1E-6A / cm ² or less can be obtained was defined as the curing time. If the pencil hardness is 5H or more, it can be said that the film has good scratch resistance. If the curing time is 2 minutes, continuous film formation of Roll to Roll is realistic and good. If it is 1 minute, continuous film formation of Roll to Roll can be performed more reliably, so it is very good. .. In the case of 5 minutes or more, it was judged as unsuitable ×.

If both flatness and roll-to-roll compatibility are satisfied, it is considered that a coil with an insulating film that functions as an electronic device substrate can be obtained, so the overall evaluation was passed.

In Experiment No. 2-1, since the amount of acetic acid was small, the molecular weight was not increased well as a ladder polymer, the reflow property was low, and the flatness was poor. In 2-5, gelation occurred during reflux due to too much acetic acid, and the coating solution could not be synthesized. Since 2-6 has less organic tin, the heat treatment time becomes longer. In 2-10, the amount of organic tin added was too large, so gelation occurred during reflux and the coating liquid could not be synthesized. Since the amount of water in 2-11 is small, the ethoxy group of phenyltriethoxysilane, which is a raw material, remains excessively, and the heat treatment time becomes long. Since 2-14 had too much water, it became a poorly soluble resin and a coating liquid could not be obtained. Probably because, in addition to the ladder polymer, a polymer having a three-dimensional random network structure was also produced at the same time. Since the temperature of distilling under reduced pressure was low in 2-15, low molecular weight polycondensates remained, which volatilized during the heat treatment and became repellent. Since there were many repellents, a short circuit occurred and it did not function as an insulating film. In 2-20, the temperature at the time of distillation under reduced pressure was too high, so that the ladder polymers were three-dimensionally connected to form a high molecular weight resin, which was not dissolved in the solvent. Since the heat treatment temperature of 2-21 was low, the condensation reaction of the ethoxy group and the silanol group in the membrane was not completed, and a high leakage current was exhibited due to these residual polar groups. In 2-26, the heat treatment temperature was too high, so that the phenyl group was decomposed and cracks were generated. The other experimental numbers shown in Table 2 are within the scope of the present invention and have passed the comprehensive evaluation.

Finally, a Roll to Roll film formation test was carried out using the flattening film forming coating solution having the composition of Experiment No. 2-8. For the film formation test, a stainless steel foil with a thickness of 50 μm, a width of 300 mm, and a length of 200 m was used. Represents the original finish of the stainless steel.) The stainless steel foil was wound around a 6-inch core made of Bakelite and rolled into a roll, which was attached to the unwinding part. The viscosity of the coating liquid was 10 mPa · s and the solid content concentration was 31%. The coating was performed using a plurality of gravure rolls having different cell volumes, and those having a dry film thickness of about 3 μm were selected. The outline of the R2R (Roll to Roll) film forming apparatus used is the same as that shown in FIG. The stainless steel foil was conveyed with a total tension of 100 N. An EPC (edge position control) sensor was attached to the winding part, and the edges of the foil were aligned, and the winding was wound on a 6-inch core made of Bakelite. Both the drying furnace and the heat treatment furnace are heated by an infrared panel heater and hot air. The drying furnace had a total length of 8 m and was operated with the set temperature inside the furnace set to 100 ° C. Atmosphere heated to 100 ° C. was blown as hot air. The heat treatment furnace has a length of 12 m and the set temperature in the furnace is set to 380 ° C. Nitrogen heated to 380 ° C. was blown as hot air. In the cooling zone, room temperature air was blown from above and below the stainless steel foil. The length of the cooling zone was 2 m. The total length from unwinding to winding was 35m. A stainless steel foil was passed through the plate at a transport speed of 4 mpm, coated, dried and heat-treated, and the stainless steel foil with a flattening film was wound up as a roll of about 150 m.

The calculated drying treatment time is 2 minutes and the heat treatment time is 3 minutes, but when a thermocouple is attached to the stainless steel foil and transported at 4 mpm, the temperature of the stainless steel foil substrate begins to rise in the drying oven until it reaches 100 ° C. It was found that the time for holding at 100 ° C. for about 1 minute was about 1 minute. As for the heat treatment furnace, after the stainless steel foil at about 100 ° C. enters the heat treatment furnace, it takes 1.5 minutes for the temperature of the stainless steel foil to rise to 380 ° C. and 1.5 minutes for the stainless steel foil to be held at 380 ° C. It turned out to be. Therefore, the solvent such as toluene in the film coated with the gravure coater evaporates and is removed in the drying furnace, and after entering the heat treatment furnace, the temperature range in which reflow of 200 to 250 ° C. is likely to occur within about 1 minute is reached. After passing through, the film is leveled and the film is cured in the remaining 2 minutes.

When the pencil hardness of the obtained roll of stainless steel foil with a flattening film was measured according to JIS K5600, a hardness of 7H was sufficient for scratch resistance. When the cross section of the stainless steel foil with a flattening film was observed by SEM, the film thickness was 3.0 μm. When the leak current was measured with a 1 cm square upper electrode attached, it was 1E-9 A / cm ² . The surface roughness Ra in the width direction of the coil by the stylus type roughness meter was 12 nm. The film was scraped off and thermogravimetric analysis was performed in nitrogen gas to confirm the heat resistance. The measurement results are shown in Table 2. The temperature showing a 5% weight loss exceeded 500 ° C, suggesting that the heat resistance up to 400 ° C is sufficient. Next, in order to evaluate the moisture resistance, the substrate with the film was stored in a constant temperature and humidity chamber at 85 ° C. and 85% RH (relative humidity), and the change in leakage current was examined. The leak current was 1E-9A / cm ² without any change until after storage for 200 hours, and it was confirmed that there was no deterioration in film quality.

Claims (8)

In an alcohol solvent, add 0.1 mol or more and 1 mol or less of acetic acid and 0.005 mol or more and 0.05 mol or less of organic tin as a catalyst to 1 mol of phenyltrialkoxysilane, and use water of 2 mol or more and 4 mol or less. After hydrolysis, the phenylsilsesquioxane ladder polymer resin and silica fine particle-containing ketone solvent obtained by distilling off the organic solvent containing the one produced by hydrolysis at a temperature of 160 ° C. or higher and 210 ° C. or lower under reduced pressure are used. In the form of silica fine particles and silica fine particles, the silica fine particle-containing ketone solvent is produced by hydrolyzing alkoxysilane under a basic catalyst in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. A flattening film-forming coating solution containing a hydrolysis-condensation reaction product of an alkoxysilane that does not take . In an alcohol solvent, add 0.1 mol or more and 1 mol or less of acetic acid and 0.005 mol or more and 0.05 mol or less of organic tin as a catalyst to 1 mol of phenyltrialkoxysilane, and use water of 2 mol or more and 4 mol or less. After hydrolysis, the resin of the phenylsilsesquioxane ladder polymer obtained by distilling off the organic solvent containing the one produced by hydrolysis at a temperature of 160 ° C. or higher and 210 ° C. or lower under reduced pressure is used as a ketone solvent containing silica fine particles. A method for producing a dissolved flattening film-forming coating liquid, wherein the silica fine particle-containing ketone solvent hydrolyzes alkoxysilane in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone under a basic catalyst. A method for producing a flattening film-forming coating liquid, which comprises silica fine particles and a hydrolysis / condensation reaction product of an alkoxysilane that does not take the form of silica fine particles. After the coating liquid according to claim 1 is applied to the metal foil coil, the surface of the metal foil coil is coated with a thickness of 2.0 μm or more by reflowing and film curing in a heat treatment process of 300 ° C. or higher and 450 ° C. or lower in an inert gas atmosphere. A metal leaf coil with a flattening film coated with a film of a phenylsilsesquioxane ladder polymer having a Ra of 0.0 μm or less and a Ra in the direction perpendicular to rolling of 30 nm or less. The metal foil coil according to claim 3, wherein the metal foil is a stainless steel foil. The coating liquid according to claim 1 is applied to a metal foil so as to have a film thickness of 2.0 μm or more and 5.0 μm or less, and is passed through a heat treatment furnace at 300 ° C. or more and 450 ° C. or less in an inert gas atmosphere to reflow and film. A method for manufacturing a metal leaf coil with a flattening film that is wound after being cured. The method for manufacturing a metal foil coil according to claim 5, wherein the metal foil is a stainless steel foil. Hydrolysis condensation reaction product of silica fine particles and alkoxysilane in the form of silica fine particles, which is produced by hydrolyzing alkoxysilane under a basic catalyst in an organic solvent selected from methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. A ketone solvent containing silica fine particles including. A step of mixing 0.5 to 85 mol of an organic solvent selected from methyl ethyl ketone, methyl isobutylken, and cyclohexanone with 1 mol of alkoxysilane, and stirring the mixture to prepare a solution 1.
A step of mixing 0.8 to 8 mol of water and 0.1 to 6 mol of a basic catalyst with respect to 1 mol of alkoxysilane to prepare a solution 2.
The method for producing a silica fine particle-containing ketone solvent according to claim 7, further comprising a step of dropping the entire amount of the solution 2 into the solution 1 while stirring the solution 1 and further stirring after the dropping is completed.

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