JPH03213801A - Production of hardened film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a cured film having a uniform reflected light color and high productivity by applying a liquid composition to a substrate. It is something.

[Prior Art] It has been strongly desired to improve the optical functions of glass and plastic products, particularly the reflective function, from the viewpoint of effective use of light rays.

For example, if anti-reflection treatment is not applied to the cathode ray tubes and front panels of display devices such as televisions, personal computer word processors, and calculators, the displayed objects may become invisible due to the reflection of light rays when they are installed, or small objects may become extremely difficult to see. There is a problem in that it causes discomfort to the eyes, and as it progresses further, the eyes feel tired and the efficiency of use decreases. In particular, there is a strong desire to improve the optical features of television screens, which are becoming more and more multi-functional.

Improving the optical functionality of glass and plastic substrates
Conventionally, this has been achieved by forming an antireflection film or a reflection increasing film on a substrate using a vacuum deposition method or the like.

In this case, it is known that the selection of the thickness and refractive index of the material coated on the substrate is important in order to maximize the antireflection effect or the increase in reflection. For example, in a single layer coating, a material with a lower refractive index than the base material is used to
It is known that selecting the optical film thickness to be 4 or an odd number multiple thereof can provide the minimum reflectance, that is, the maximum transmittance.

The optical film thickness here is given by the product of the refractive index of the coating forming material and the film thickness of the coating. Further, it is possible to select the antireflection layer of the coating, and in this case, by appropriately selecting the film thickness and refractive index of each layer, the desired reflected light color and antireflection effect can be obtained. Several proposals regarding these have already been made (optical technology) Contact Vo1.9.Nα8.17-23 (
1971).

The anti-reflection film or increased reflection formed by such a vapor deposition method may cause the following problems depending on the application.

(1) Since a high degree of vacuum is required, there are restrictions on the size and material of the substrate to be treated. Moreover, manufacturing time becomes longer, and productivity and economical efficiency decrease.

(2) Usually requires considerable heating, which may cause problems such as deformation and decomposition depending on the base material.

(3) The coating forming material used is mainly an inorganic oxide, and although it forms a dense film, in the case of a plastic base material, heat resistance and adhesion are likely to deteriorate due to differences in linear expansion coefficients.

On the other hand, JP-A-58-46301 discloses the production of a two-layer antireflection film using a liquid composition. This method has solved the above problems to some extent. This document discloses an example of a dip coating method for both the first layer and the second layer, and a spin coding method for both the first layer and the second layer. The former method causes color unevenness in the reflected light on the upper and lower sides and on the front and back sides of the substrate, and only products with no commercial value can be obtained. In addition, the latter has low productivity and becomes a very costly product.
Furthermore, it is difficult to apply it to large-area base materials.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a cured film that is free from color unevenness in reflected light and has high productivity.

[Means for Solving the Problems] That is, the present invention provides a method in which a liquid composition is placed in a tank provided with an outlet at the bottom, a substrate is immersed in the liquid composition, and then the liquid is poured from the outlet. The liquid composition is applied to a substrate by removing the composition and lowering the liquid level of the liquid composition at a constant speed or by continuously changing the speed, and then heat-curing and/or drying. The present invention relates to a method for producing a cured film.

The base material referred to in the present invention may be any material as long as it fulfills the purpose of the present invention, but from the viewpoint of applying the liquid composition, it may be a flat plate, a molded article with curvature, or even a cylindrical article. It is preferably applied to. Moreover, the molded product is preferably applied not only to a spherical surface but also to a molded product having an aspherical surface.

When the purpose is to improve the transmittance brought about by improving the antireflection property, it is preferable to apply it to a transparent base material.

The liquid composition for forming a film that imparts antireflection properties to such substrates may consist of only a film-forming substance, or may contain various volatile solvents to impart the necessary coating workability. be able to. Here, the liquid composition is a composition having a viscosity within a range to which ordinary coating operations can be applied, and is 10 poise or less, preferably 1 poise or less at the application temperature. That is, it is difficult to obtain a uniform coating film with a liquid composition having a viscosity higher than this.

The method for producing a cured film in the present invention involves putting a liquid composition into a tank with an outlet at the bottom, immersing a substrate therein, and then removing the liquid composition from the outlet. This is a method of uniformly applying a liquid composition to both or one side of a substrate by lowering the liquid level at a constant speed or by continuously changing the speed, particularly by gradually decreasing the speed from a high speed. The rate of descent of the liquid level and the atmospheric conditions must be determined experimentally, but from the perspective of controlling the thickness of the thin film, the rate of descent should be 0.5 to 40 an/min, more preferably 1 to 20 cm/min.
done in minutes. Furthermore, the number of substrates to be coated at one time should be determined from the viewpoint of productivity, and is not particularly limited. Furthermore, if the above-mentioned rate of descent is slower than this, productivity will drop significantly and the benefits of using the liquid removal coating method will not only be lost, but also concentration unevenness will easily occur on the surface layer of the liquid composition, resulting in uneven film thickness. etc., occurs. This causes problems in terms of appearance.

Furthermore, if the coating speed is faster than this, there are problems such as large film thickness unevenness occurs on the upper and lower sides and front and rear surfaces of the substrate, making it impossible to obtain a uniform antireflection film.

Further, in adjusting the descending speed, it is preferable to prevent the liquid composition from causing turbulence. This is because if the vertical disturbance of the descending surface becomes severe, unevenness in film thickness will occur, making it impossible to obtain a uniform anti-reflection or reflection-enhancing film. In other words, the shape of the tank and the size of the outlet must be determined experimentally in accordance with the shape of the substrate and the liquid composition.

Adhesion can also be improved by applying various chemical and physical treatments to the base material during application.

The liquid composition may be used if the coating formed from it forms an anti-reflection or reflection-enhancing film, that is, the above-mentioned optical technology [Tact Vol. 1.9. No, 8. 17-23 (197
The composition is not particularly limited as long as it has a composition that forms an antireflection film that satisfies the requirements described in .

For example, from the viewpoint of applying a liquid composition, it is preferable to use an organic material or an inorganic material having the ability to form a transparent film dispersed or dissolved in a solvent.

Further, those that are liquid themselves can be used alone, but they can also be used after being diluted with a suitable solvent. These materials can be used within the range of 2.
It is also possible to use a mixture of more than one species.

Organic materials used as film-forming substances with a relatively high refractive index that are preferably used to form a cured film include:
For example, cure polystyrene, polystyrene copolymers, polycarbonates, various polymer compositions containing aromatic rings other than polystyrene, heterocycles, alicyclic groups, or halogen groups other than fluorine, melamine resins, phenolic resins, or epoxy resins. Various thermosetting resin-forming compositions as agents, urethane-forming compositions comprising alicyclic or aromatic isocyanates and/or these and polyols,
and by introducing a double bond into the above compound,
Compositions containing various modified resins or prepolymers that enable radical curing are preferably used.

On the other hand, inorganic materials that have film-forming properties and can be dispersed in solvents or are liquid themselves are used. Typical examples include alkoxides of various elements, salts of organic acids, There are coordination compounds combined with coordination compounds. Suitable examples of these include titanium tetraethoxide, titanium tetrapropoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-
$CC-butoxide, titanium tetra-1e "1-butoxide, aluminum triethoxide, aluminum treaty propoxide, aluminum tributoxide, antimony triethoxide, antimony tributoxide,
Zirconium tetraethoxide, zirconium tetra-
Metal alcoholate compounds such as 1-propoxide, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium tetra-5ee-butoxide, zirconium tetra-1erl-butoxide, and even diisopropoxytitanium bisacetylacetonate. , di-butoxytitanium bisacetylacetonate, di-ethoxytitanium bisacetylacetonate, bisacetylacetone zirconium, aluminum acetylacetonate, aluminum di-n-butoxide monoethylacetoacetate, aluminum di-propoxide monomethylacetoacetate, tri- Examples include chelate compounds such as lobe toxide zirconium monoethyl acetoacetate, zirconyl ammonium carbonate, and active inorganic polymers containing zirconium as a main component.

On the other hand, oxides of metal elements such as aluminum, titanium, zirconium, antimony, and silicon are examples of inorganic compounds that cannot be used alone but can be used with the above-mentioned organic or inorganic materials to the extent that transparency is not impaired. is preferably used.

These are provided in the form of fine particles or as a colloidal dispersion in water and/or other solvents. These are mixed and dispersed in the above organic material or inorganic material.

In addition, materials with a low refractive index can also be used, and in addition to the organic materials mentioned above, vinyl copolymers including acrylic ones, polyester (including alkyd) polymers, Examples include cellulose polymers, urethane polymers, various curing agents for curing these, and compositions having curable functional groups.

Furthermore, it is possible to include organically substituted silicon compounds. These organosilicon compounds are compounds represented by the general formula % or their hydrolysis products. Here, R1 and R2 are each an alkyl group, an alkenyl group, an aryl group, or a hydrocarbon group having a halogen group, an epoxy group, an amino group, a mercapto group, a methacryloxy group or a cyano group, and X is an alkoxyl group, an alkoxyalkoxyl group, Hydrolyzable substituent selected from halogen or acyloxy group, a and b are 0 and 1, respectively
Or 2 and a tenth is 0. 1 or 2.

Other preferred film-forming substances made of organic materials with a relatively low refractive index include vinyl copolymers containing acrylics that do not contain aromatic rings, various fluorine-substituted polymers, and polymers that do not contain aromatic rings. There are compositions comprising polyester (including alkyd) polymers, cellulose derivatives, silicone polymers, hydrocarbon polymers, prepolymers thereof, or those having a curable functional group among these, and a curing agent.

Inorganic materials include inorganic silicon compounds such as various alkyl silicates, various aryl silicates, and various tetracarboxysilanes. Specific representative examples of these inorganic silicon compounds include methyl silicate, ethyl silicate, n-propyl silicate, 1so
-Propyl silicate, n-butyl silicate, 5ec
-butyl silicate, 1erl-butyl silicate, n
Examples include -hexyl silicate, phenyl silicate, tetraacetoxysilane, tetra(2-methacryloxy)ethoxysilane, and tetramethoxyethoxysilane.

Furthermore, organically substituted silicon compounds are also preferably used. These organosilicon compounds are organosilicon compounds represented by the general formula % and/or hydrolysates thereof.

Here, R3 and R4 each represent a hydrocarbon having an alkyl group, an alkenyl group, an aryl group, a halogen group, a methacryloxy group or a cyano group.

R5 is an alkyl group, alkoxyalkyl group, or acyl group having 1 to 8 carbon atoms, and C and d are 0 or 1.
and c+d is 1 or 2.

Specific representative examples of these organosilicon compounds include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, and β-glycidoxyethyltriethoxysilane. - glycidoxyethyltrimethoxysilane,
β-glycidoxyethyltriethoxysilane, α-glycidoxypropyltriethoxysilane, α-glycidoxypropyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane , γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane, γ-
Glycidoxypropyltrimethoxyethoxysilane, γ
Glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltrimethoxysilane, β-glycidoxybutyltriethoxysilane, γ - glycidoxybutyltrimethoxysilane,
γ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl)methyltrimethoxysilane, (3,4-epoxycyclohexyl) ) Methyltriethoxysilane, β-
(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltripropoxysilane, β-(3,4-epoxycyclohexyl)ethyltripropoxysilane
-Epoxycyclohexyl)ethyltributoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxyethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, γ-(3,
4-Epoxycyclohexyl)propyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)propyltriethoxysilane, δ(3,4-epoxycyclohexyl)butyltrimethoxysilane, β-(3,4-epoxycyclohexyl)butyl Triethoxysilane, glycidoxymethylmethyldimethoxysilane, glycidoxymethylmethyljethoxysilane, α-glycidoxyethylmethyldimethoxysilane, α-glycidoxyethylmethyljethoxysilane, β-glycidoxyethylmethyldimethoxy Silane, β-glycidoxyethylmethyljethoxysilane, α-glycidoxypropylmethyldimethoxysilane, α-glycidoxypropylmethyljethoxysilane, β-glycidoxypropylmethyljethoxysilane, β-glycidoxypropyl Methyljethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane,
γ-glycidoxypropylmethyldimethoxyethoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyljethoxysilane, γ-glycidoxypropylvinyl dimethoxysilane,
γ-glycidoxypropylvinyljethoxysilane, γ
-glycidoxypropylphenyldimethoxysilane, γ
-Epoxy group-containing organosilicon compounds such as glycidoxypropylphenyldiethoxysilane and their hydrolysates, as well as methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, and methyltributoxysilane. ,
Ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-lylopropyl Trimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane, 3.3.3-1 Lifluoropropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane , γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-(aminoethyl)-
Trialkoxy, triazyloxy, or triphenoxysilanes such as γ-aminopropyltrimethoxysilane, β-cyanoethyltriethoxysilane, methyltriphenoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, or their hydrolysis dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyljethoxysilane, phenylmethyljethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyljethoxysilane, dimethyldiacetoxysilane, γ-methyclyloxy Propylmethyldimethoxysilane, γ-methacryloxypropylmethyljethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyljethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyljethoxysilane, methyl Examples include dialkoxysilanes or diacyloxysilanes such as vinyldimethoxysilane and methylvinyljethoxysilane, or hydrolysates thereof.

These organosilicon compounds are preferably used after being hydrolyzed in order to lower the curing temperature and further promote curing.

Furthermore, various curing agents can be used as curing accelerators, and specific typical examples include aluminum acetylacetonate, aluminum ethyl acetoacetate bisacetylacetonate, aluminum bisacetoacetate acetylacetonate, and aluminum di-n -butoxide monoethyl acetoacetate, aluminum di-
Aluminum chelate compounds such as mepropoxide monomethyl acetoacetate, titanate compounds such as tetraisobutoxytitanium, diisopropoxybis(acetylacetonate) titanium, alkali metals and alkaline earth metals of various organic carboxylic acids, etc. The amount added should be determined within a range that satisfies requirements regarding the performance of the cured product and the refractive index of the coating.

Two or more of these organic materials, inorganic materials, and organosilicon compounds may be used in combination as long as transparency is not impaired.

On the other hand, although it cannot be used alone, it has adhesive properties with the base material,
Fine particulate silica is preferably used as an inorganic compound that can be used with the above-mentioned organic materials, inorganic materials, organosilicon compounds, and mixtures thereof for the purpose of improving surface hardness and dyeing properties as long as transparency is not impaired. used. As the particulate silica, colloidally dispersed silica sol is particularly preferably used from the viewpoint of transparency.

These compositions are usually applied diluted in volatile solvents. The solvent used is not particularly limited, but
The use should be determined by taking into consideration the stability of the composition, wettability to the substrate, volatility, etc. Moreover, it is also possible to use not only one type of solvent but also a mixture of two or more types.

Various surfactants may be used in the liquid composition of the present invention for the purpose of improving the flow during application, and in particular, block or graft copolymers of dimethylsiloxane and alkylene oxide, and Fluorine surfactants are effective.

Furthermore, it is also possible to easily add an ultraviolet absorber to the composition for the purpose of improving weather resistance, and an oxidation preventive agent as a method for improving heat deterioration resistance.

By heating and/or drying the liquid composition applied in this manner, an antireflection film can be obtained. As a heating method, hot air, infrared rays, etc. can be used. The heating temperature should be determined depending on the substrate to be applied and the liquid composition used, but is usually 50 to 250°C, more preferably 60 to 200°C.
°C is used. If the temperature is higher than this, thermal decomposition may occur, causing problems such as yellowing.

Furthermore, it is also possible to use curable functional groups such as double bonds in polymers or oligomers and to cure them using radiation such as ultraviolet rays, electron beams, and gamma rays.

Further, the thickness of the coating film of the present invention is controlled by the solid content of the liquid composition and coating conditions.

Typical base materials of the present invention include glass and plastic materials. The above plastic materials include polymethyl methacrylate-1 and its copolymer,
Polycarbonate, diethylene glycol bisallyl carbonate polymer (CR-39), polyester especially polyethylene terephthalate and unsaturated polyester, acrylonitrile-styrene copolymer, vinyl chloride,
Polyurethane, epoxy resin, etc. are preferably used. Furthermore, base materials such as the above-mentioned plastics and glass coated with coating materials are also preferably used.

In particular, various physical properties such as adhesion, hardness, chemical resistance, durability, and dyeability can be improved by coating the anti-reflection or reflection-enhancing film in contact with the substrate of the present invention. In addition, in order to improve the hardness, it is possible to use various materials that have been applied as coatings for hardening the surface of plastics (Japanese Patent Publication No. 50-28092, Japanese Patent Publication No. 50-28446, Japanese Patent Publication No. 50-28446, No. 50-39449,
Japanese Patent Publication No. 51-24368, Japanese Patent Publication No. 52-112698
No., Special Publication No. 57-2735).

The present invention will be described in detail below using Examples, but is not limited thereto.

Example 1 (1) Preparation of undercoating composition (a) Preparation of vinyltriethoxysilane hydrolyzate 279 g of acetic acid was added to 3720.2 g of vinyltriethoxysilane.
．． Add 1g and control the temperature at 20℃ to 0.0
1,053.9 g of a 5N aqueous hydrochloric acid solution was added dropwise to the stirrer to obtain a hydrolyzate.

(b) Preparation of methyltrimethoxysilane hydrolyzate Add 406 g of acetic acid to 5332.8 g of methyltrimethoxysilane.
．． Add 3g and control the temperature at 20℃ to 0.0
2107.7 g of a 1N aqueous hydrochloric acid solution was added dropwise to the mixture while stirring to obtain a hydrolyzate.

(C) Preparation of paint The respective silane hydrolysates prepared in (a) and (b) above were mixed, and further 1146.67 g of xylene, 286.67 g of butyl acetate, and 21 g of silicone surfactant were added.
．． ．． 5 g and 28.67 g of sodium acetate were added and uniformly dissolved to form a paint.

(2) Application and curing of undercoat The undercoat composition prepared in the previous section (1) is applied to a polymethyl methacrylate casting plate whose entire surface on one side is coated with a releasable film using a dip coating method (pulling speed 20 cm/min). 60℃
It was cured for 30 minutes in a hot air dryer to obtain a transparent substrate.

(3) Preparation of the first layer coating composition In a beaker,
-Propyl alcohol 1.781. .

72g 1 ethyl alcohol 1760.69g, acetic acid 75g
．． Add 15 g and stir. Further, 1.1 g of silicone surfactant was added, and methanol-dispersed colloidal silica (average particle size 1.
2±1 mμ, solid content 30%) 67 g of I-64 and 212.93 g of tetra-n-butyl titanate were added to prepare a coating composition.

(4) Preparation of second layer coating composition (a) Preparation of silane hydrolyzate 550 g of γ-glycidoxypropyltrimethoxysilane
125.85 g of a 0.01N hydrochloric acid aqueous solution was added dropwise and mixed with stirring while controlling the temperature at 10°C. After the dropwise addition was completed, stirring was continued for an additional hour at room temperature to obtain a silane hydrolyzate.

(b) Preparation of coating composition 9685.65 g of methyl alcohol, 3179.79 g of ethylene glycol, 126.98 g of water, and 15.42 g of silicone surfactant were added to 669.08 g of the silane hydrolyzate with stirring.

1.285 g of the same methanol-dispersed colloidal silica used in (3) and aluminum acetylacetoner)
38.55 g was added and sufficiently stirred to prepare a coating composition.

(5) Coating and curing First, the first layer coating composition prepared in the previous item (3) was applied to the substrate in the previous item (2) by a dip coating method (pulling speed 10 cm, minutes), and the coating composition was coated at 90°C for 90 minutes. Heated for minutes. The second layer coating composition was then applied on top of the first layer as follows.

That is, the second layer coating composition is placed in a tank with an outlet at the bottom, and the base material provided with the first layer coating wave film is immersed in the tank.
The second layer coating composition was applied by lowering the liquid level at a constant rate of cm/min. Thereafter, it was heated and cured at 90° C. for 4 hours. After that, when the peelable coating was removed,
The obtained substrate had a total light transmittance of 94.9%, only one side had a good antireflection effect, and the color of the reflected light was a uniform reddish-purple color with no unevenness over the entire surface.

Example 2 Everything was carried out in the same manner as in Example 1 except that the second layer coating film was not provided and the coating method of the first layer coating film was changed as follows.

(1) Applying the first layer coating composition, using the same method as the second layer coating composition of Cure Example 1,
Applied and cured. The descending speed was changed to a constant speed of lOc+n/min, and the liquid level was lowered for coating. Thereafter, the peelable coating was removed, and the obtained substrate had a total light transmittance of 89.2% and only one side had a good reflection increasing effect.

Example 3 (1) Preparation of substrate for coating Tetrabromobisphenol A ethylene oxide 2
A monomer containing a polyfunctional acrylate monomer with 0.9 mol of hexamethylene diisocyanate added to 1 mol of a hydroxyl group-containing compound obtained by condensing 1 mol of acrylic acid to a molar adduct by esterification, and 30 styrene polymers. A base material obtained by cast polymerization using isopropyl peroxide as a polymerization initiator was subjected to low-temperature plasma treatment to obtain a surface-treated base material for coating. The refractive index of the obtained resin was 1.61.

(2) Coating, Curing, and Evaluation A substrate was obtained in the same manner as in Example 1, except that the substrate was changed to the substrate obtained in section (1) above, and the first layer was not provided.

The obtained substrate had a total light transmittance of 92.5%, only one side had a good antireflection effect, and the color of reflected light was uniform with a pale magenta color.

[Effects of the Invention] The anti-reflection or reflection-increasing film obtained by the production method of the present invention has an even and uniform reflected light color, and has extremely high commercial value. Furthermore, compared to conventional vapor deposition processes, productivity is significantly improved, and furthermore, it can be easily applied to articles having a large area.

Claims (1)

[Claims] (1) Put the liquid composition into a tank with an outlet at the bottom,
After the substrate is immersed in the liquid composition, the liquid composition is removed from the outlet and the liquid level of the liquid composition is lowered at a constant speed or by continuously changing the speed,
A method for producing a cured film, which comprises applying a liquid composition to a substrate and then heating and curing and/or drying the composition.