JP2013116427A - Method for manufacturing coated article and mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a coated article such as a mirror that can suppress cracks to be generated on a cured coating film when forming the cured coated article on a glass substrate by a two-coat-one-bake method.SOLUTION: The method for manufacturing a coated article such as a mirror includes: a step of forming a first coating layer 16A by coating a first coating material on a surface of a reflecting layer 14 of the glass substrate 12 having the reflecting layer 14 on one surface; a step of forming a second coating layer 18A having difference of the curing temperature from the first coating layer 16A is within 30°C by coating a second coating material on the first coating layer 16A; and a step of heating and simultaneously curing the first coating layer 16A and the second coating later 18A.

Description

  The present invention relates to a method for manufacturing a coated article and a mirror.

  In recent years, from the viewpoint of global environmental problems, many attempts have been made to reduce the amount of fossil fuel used. As one of them, a solar heat collection system using solar heat is known. Examples of the solar heat collection system include a solar heat collection system having a heat collection tube provided with a heat medium such as water or an inorganic salt, and a mirror that reflects sunlight and collects it in the heat collection tube. In the solar heat collecting system, sunlight is reflected by a mirror and collected in a heat collecting tube, and heat energy is obtained by heating the heat medium of the heat collecting tube with the heat of the sunlight.

As the mirror, a mirror having a glass substrate, a reflective layer formed on the glass substrate, and a rust preventive coating film formed on the reflective layer is widely used. Usually, a silver film is formed as a reflective layer on a transparent glass substrate, but the silver film is very easily oxidized. Therefore, a rust-preventing coating film is formed which covers a copper protective layer as a protective layer for the silver film or directly on the silver film to suppress corrosion and alteration of the silver film. The anticorrosive coating includes, for example, a thermosetting resin (epoxy resin, alkyd resin, polyester resin, acrylic resin, etc.) and an inorganic pigment component (carbonic acid) for suppressing the curing shrinkage of the coating that occurs when it is cured. It is formed by applying a rust-preventive paint containing calcium, talc, etc.) and then drying and curing (for example, Patent Document 1).
However, since the mirror used in the solar heat collection system is used for a long time in a harsh environment such as a desert area, resin deterioration (photodegradation, degradation due to hydrolysis, etc.) in the anticorrosive coating film, Due to the elution and removal of the inorganic pigment component, there is a problem that the internal stress of the anticorrosive coating film increases and the anticorrosive coating film peels off. Therefore, as a technique for solving the problem, a cured coating film made of a fluororesin paint is further formed on the rust preventive coating film to improve durability.

On the other hand, as a manufacturing method of a coated article in which two layers of a cured coating film are laminated on a glass substrate, the following first coating process, second coating process and curing process are performed because it is advantageous in terms of resource saving and energy saving. A so-called two-coat one-bake manufacturing method with a small number of baking is widely used.
First application step: a step of applying a first paint on a glass substrate to form a first application layer.
Second coating step: a step of forming a second coating layer by coating the second coating material on the first coating layer.
Curing step: a step of baking and curing the first coating layer and the second coating layer simultaneously.

JP 2007-45849 A

  However, when a coated article having a cured coating film on a glass substrate is produced by the 2-coat 1-bake method, cracks may occur in the formed cured coating film.

  It is an object of the present invention to provide a method for producing a coated article and a method for producing a mirror capable of suppressing the occurrence of cracks in the cured coating film when a cured coating film is formed on a glass substrate by a 2-coat 1-bake method. To do.

The present invention employs the following configuration in order to solve the above problems.
[1] A method for producing a coated article, in which the following first coating step, second coating step, and curing step are sequentially performed to form a cured coating film on one surface side of a glass substrate.
First coating step: a step of forming a first coating layer by coating a first coating on one surface side of the glass substrate.
Second coating step: a step of coating the first coating layer on the first coating layer to form a second coating layer having a curing temperature difference of 30 ° C. or less with respect to the first coating layer.
Curing step: a step of heating the first coating layer and the second coating layer and simultaneously curing the first coating layer and the second coating layer to form a cured coating film.
[2] The method for manufacturing a coated article according to [1], wherein the first paint and the second paint are applied by a curtain flow coat method.
[3] The first coating material is selected from the group consisting of at least one amine catalyst selected from the group consisting of aromatic amines, aliphatic amines, amide polyamines, and polyamides, carboxylates, sulfonates, and phosphates. At least one Bronsted acid catalyst, or at least one Lewis acid catalyst selected from the group consisting of tin octylate, tributyltin dilaurate, dibutyltin dilaurate, and the second paint is an aromatic amine, At least one amine catalyst selected from the group consisting of aliphatic amines, amidopolyamines, polyamides, at least one Bronsted acid catalyst selected from the group consisting of carboxylates, sulfonates, phosphates, or octyl Selected from the group consisting of tin oxide, tributyltin dilaurate, and dibutyltin dilaurate Method for manufacturing a coated article according to contain Kutomo one Lewis acid catalyst [1] or [2].
[4] The method for producing a coated article according to any one of [1] to [3], wherein the glass substrate has a thickness of 0.5 to 10 mm.
[5] A method for producing a mirror, wherein a cured coating film is formed on the surface of the reflective layer of a glass substrate having a reflective layer on one surface by the production method according to any one of [1] to [4].
[6] The method for manufacturing a mirror according to [5], wherein the reflective layer is a reflective layer made of at least one selected from the group consisting of metals and metal oxides.

According to the method for producing a coated article of the present invention, when a cured coating film is formed on a glass substrate in the production of a coated article by the 2-coat 1-bake method, it is possible to suppress the occurrence of cracks in the cured coating film.
Moreover, according to the manufacturing method of the mirror of this invention, when forming a cured coating film on a glass substrate in manufacture of the mirror by a 2 coat 1 baking method, it can suppress that a crack arises in this cured coating film.

It is sectional drawing of the laminated body obtained by the 1st application | coating process in the manufacturing method of the mirror of this invention. It is sectional drawing of the laminated body obtained by the 2nd application | coating process in the manufacturing method of the mirror of this invention. It is sectional drawing of the mirror obtained with the manufacturing method of the mirror of this invention.

  In the specification of the present invention, a compound represented by the formula (1) is referred to as a compound (1). The (meth) acryloyl group means a methacryloyl group or an acryloyl group. The same applies to (meth) acrylic acid.

The method for producing a coated article of the present invention is a method of forming a cured coating film on a glass substrate by a 2-coat 1-bake method. In the present invention, to form a cured coating film on one surface side of a glass substrate, in addition to the form of directly forming a cured coating film on one surface of the glass substrate, other layers such as a reflective layer on the surface of the glass substrate A form in which a cured coating film is indirectly formed on one surface side of the glass substrate by forming a cured coating film on the surface of the other layer is also included.
Hereinafter, as an example of a method for producing a coated article of the present invention, based on FIGS. 1 to 3, two layers are cured on the surface of the reflective layer of a glass substrate having a reflective layer on one surface by a two-coat one-bake method. A method for producing a mirror by forming a coating film will be described in detail. That is, this example is an example in which a cured coating film is indirectly formed on one surface side of the glass substrate.

The manufacturing method of the mirror of this embodiment is a method of performing the following 1st application process, 2nd application process, and hardening process one by one.
First application step: As shown in FIG. 1, a first coating layer 16A is formed by applying a first paint on the surface of the reflection layer 14 of the glass substrate 12 having the reflection layer 14 on one surface. .
2nd application | coating process: As shown in FIG. 2, the 2nd coating material is apply | coated on the 1st application layer 16A, and the difference of the curing temperature with the 1st application layer 16A is 30 degrees C or less. A step of forming the coating layer 18A.
Curing step: The first coating layer 16A and the second coating layer 18A are heated to cure the first coating layer 16A and the second coating layer 18A at the same time, and as shown in FIG. 3, the first curing is performed. A step of obtaining the mirror 10 by forming the coating film 16 and the second cured coating film 18 (hereinafter, these may be collectively referred to as “multilayer coating film”).

That is, the uncured first coating layer 16A and the uncured second coating layer 18A are sequentially formed on the surface of the reflective layer 14 of the glass substrate 12 having the reflective layer 14 on one surface by wet on wet. Thereafter, these two uncured coating layers are baked at once and cured, so-called two-coat one-bake method.
In the mirror 10, the surface of the reflective layer 14 on the glass substrate 12 side is a reflective surface that reflects light.

[First application step]
As shown in FIG. 1, a first coating layer 16 </ b> A is formed by applying a first paint on the surface of a reflective layer 14 made of a glass substrate 12 having a reflective layer 14 on one surface.
Examples of the method for applying the first paint include a method using a brush, a roller, a spray, a flow coater, an applicator and the like. Among these, from the viewpoint of productivity of the mirror 10 and ease of control of the film thickness of the first coating layer 16A, coating with a flow coater is preferable, and a curtain flow coating method is particularly preferable.

  10-100 micrometers is preferable and, as for the dry film thickness of 16 A of 1st application layers, 10-50 micrometers is more preferable. If the film thickness of the first coating layer 16A is equal to or greater than the lower limit value, the base concealing property is easily obtained, and the rust preventive effect of the reflective layer 14 is easily obtained. Further, if the film thickness of the first coating layer 16A is equal to or less than the upper limit value, the first coating is difficult to flow, so that coating film unevenness is unlikely to occur.

The curing temperature of the first coating layer 16A, that is, the temperature at which the curing reaction of the first coating layer 16A proceeds is preferably 10 to 150 ° C. or less, and preferably 20 to 120 ° C. If the curing temperature of the first coating layer 16A is equal to or higher than the lower limit value, the remaining unreacted material in the coating film is reduced. If the curing temperature of the first coating layer 16A is equal to or lower than the upper limit, curing of the coating proceeds rapidly, so that the physical properties of the coating are not significantly reduced.
The curing temperature of the first coating layer 16A can be appropriately adjusted by selecting the type of resin component, curing agent, and curing catalyst described later, that is, selecting the curing system of the first coating layer 16A.
The curing temperature of the coating layer in the present invention is determined by using a viscosity / viscoelasticity measuring device (for example, manufactured by Eiko Seiki Co., Ltd., product name: viscosity / viscoelasticity measuring device “Rheo Stress 6000”) at a temperature rising rate of 10 ° C./min Under these conditions, the temperature at which the viscosity changes rapidly when the temperature is raised is defined as the curing temperature.

(Glass substrate)
The shape of the glass substrate 12 may be a flat plate shape or a curved shape so that the reflective layer 14 side is concave.
As the material of the glass substrate 12, known glass for mirrors can be used, and examples thereof include soda lime glass. When the mirror 10 is used for an application such as a mirror used in a solar heat collecting system, the glass substrate 12 is more preferably tempered glass because it is used outdoors such as in the desert and may be damaged by collision with sand or the like.

  The lower limit of the thickness of the glass substrate 12 is preferably 0.1 mm and more preferably 0.5 mm from the viewpoint of strength. The upper limit of the thickness of the glass substrate 12 is preferably 10.0 mm and more preferably 5.0 mm from the viewpoint of thermal conductivity.

The glass substrate 12 has a reflective layer 14 on one surface. The reflective layer 14 is preferably a reflective layer made of at least one selected from the group consisting of metals and metal oxides. The metal and metal oxide forming the reflective layer 14 are not particularly limited as long as a high reflectance can be secured when the reflective layer is formed.
When the reflective layer 14 is made of a metal, the metal preferably contains at least one element selected from the group consisting of titanium, molybdenum, manganese, aluminum, silver, copper, gold, and nickel. It is preferable to contain. Corrosion resistance may be enhanced by mixing silver or a metal such as titanium. In this case, the silver content in the reflective layer 14 is preferably 60% by mass or more, particularly preferably 100% by mass.

When the reflective layer 14 is made of a metal oxide, the metal oxide may be used alone or in combination of two or more. As the metal oxide for forming the reflective layer 14, titanium oxide is preferable.
Further, the reflective layer 14 may be a layer containing both a metal and a metal oxide.

As for the thickness of the reflection layer 14, 300-1500 mg / m < ² > is preferable.
The reflective layer 14 can be formed on one surface of the glass substrate 12 by a known method such as a method using a chemical reaction such as sputtering or a silver mirror reaction.
The reflective layer 14 may be a single layer or two or more layers.

  A metal protective layer may be further provided on the reflective layer 14 for the purpose of protecting the reflective layer 14. In particular, when the mirror 10 is installed in an area where the salinity concentration in the atmosphere is high, such as near the coast, an excellent anticorrosive property is required. Therefore, it is preferable to provide a metal protective layer on the reflective layer 14. Examples of the metal forming the metal protective layer include copper, nickel, nickel alloy, tin, tin alloy, and the like. Copper that is excellent in chemical stability, high in anticorrosion effect, and excellent in adhesion to the reflective layer is preferable.

(First paint)
The first paint is a paint for forming the first cured coating film 16 and includes, for example, a resin component, a pigment, and a solvent as essential components, and if necessary, a curing agent, a curing catalyst, a rheology control agent, and the like. And solvent-based coating compositions containing other components.
Examples of the resin component include acrylic resin, polyester resin, polyurethane resin, alkyd resin, fluororesin, epoxy resin, and polyether resin. Of these, acrylic resin, alkyd resin, polyurethane resin, and epoxy resin are preferred because of excellent adhesion to the reflective layer 14 or the metal protective layer, and epoxy resin is superior because of excellent moisture resistance and suppression of pigment elution. Is more preferable.
1 type may be sufficient as the resin component contained in a 1st coating material, and 2 or more types may be sufficient as it.

The pigment contained in the first paint is preferably at least one selected from the group consisting of rust preventive pigments, colored pigments and extender pigments.
The rust preventive pigment is a pigment for preventing the reflection layer 14 from being corroded or altered. The rust preventive pigment is preferably a lead-free rust preventive pigment with a low environmental load. Examples of lead-free rust preventive pigments include cyanamide zinc, zinc oxide, zinc phosphate, calcium magnesium phosphate, zinc molybdate, barium borate, and calcium cyanamide zinc.
The color pigment is a pigment for coloring the coating film. Examples of the color pigment include titanium oxide, carbon black, iron oxide, phthalocyanine blue, phthalocyanine green, quinacridone, isoindolinone, benzimidazolone, and dioxazine.
The extender pigment is a pigment for improving the hardness of the coating film and increasing the thickness of the coating film. Moreover, it is preferable to mix | blend since a cut surface can be cleaned when cut | disconnected with glass. Examples of extender pigments include talc, barium sulfate, mica, and calcium carbonate.
1 type may be sufficient as the pigment contained in a 1st coating material, and 2 or more types may be sufficient as it.

  The first paint preferably contains a pigment and a resin component in a range of pigment / resin component (mass ratio) = 0.5 to 5.0. The lower limit of the pigment / resin component (mass ratio) is preferably 0.5 because blisters are unlikely to occur in the coating film in the water resistance test and warm water resistance test, and rust is not likely to occur in the reflective layer in the salt spray test. 0.7 is more preferable, and 1.0 is more preferable. The upper limit of the pigment / resin component (mass ratio) is that the adhesion between the first cured coating film 16 and the reflective layer 14 is good, the chemical resistance and the moisture resistance are not easily lowered, and the reflective surface is squeezed. 5.0 is preferable, 4.5 is more preferable, and 4.0 is more preferable.

When the resin component does not have a crosslinkable group that provides self-curing properties, the first paint preferably contains a curing agent that forms a chemical bond (crosslink) by a crosslinking reaction with the resin component. What is necessary is just to select a hardening | curing agent suitably according to the kind of the said resin component. Examples of the curing agent include blocked isocyanate curing agents, amino resins, and organosilanes.
1 type may be sufficient as the hardening | curing agent contained in a 1st coating material, and 2 or more types may be sufficient as it.

  The blocked isocyanate curing agent is a curing agent in which the isocyanate group of the polyvalent isocyanate compound is protected. For example, the compound etc. by which the isocyanate group of the polyvalent isocyanate compound was protected by the group which can be deprotected by heating etc. are mentioned. Specific examples include compounds in which isocyanate groups are protected by reacting a polyvalent isocyanate compound with a known blocking agent such as alcohol, caprolactam, MEK oxime, or organic acid ester. A polyvalent isocyanate compound is a compound having two or more isocyanate groups.

  Examples of the polyvalent isocyanate compound include aliphatic polyisocyanate compounds such as ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, hexamethylene triisocyanate, and lysine diisocyanate; isophorone diisocyanate, dicyclohexylmethane diisocyanate, diisocyanate methylcyclohexane. And non-yellowing-modified aromatic isocyanate compounds such as m-xylene diisocyanate and p-xylene diisocyanate. Of these, non-yellowing polyvalent isocyanate compounds such as hexamethylene diisocyanate and isophorone diisocyanate are preferred.

As the polyvalent isocyanate compound, a modified product thereof can also be used. Examples of modified polyisocyanate compounds include urethane-modified products, urea-modified products, isocyanurate-modified products, burette-modified products, allophanate-modified products, and carbodiimide-modified products. Especially, an isocyanurate modified body, a burette modified body, and a urethane modified body are preferable, and an isocyanurate modified body and a burette modified body are more preferable.
The blocked isocyanate curing agent may be used alone or in combination of two or more.

Examples of amino resins include melamine resins, guanamine resins, sulfoamide resins, urea resins, aniline resins, and the like. Especially, a melamine resin is preferable at a point with a quick hardening rate.
Examples of the melamine resin include alkyl etherified melamine resins. Of these, methylolated and / or butyrololized melamine resins are more preferred.
An amino resin may be used individually by 1 type, and may use 2 or more types together.

As the organosilane, the compound (1) is preferable.
(R ¹ ) _4-k Si (OR ² ) _k (1).
However, the formula (1), ^{R 1} and ^{R 2} each independently, a monovalent hydrocarbon group having 1 to 10 carbon atoms, k is an integer of 2-4.

R ¹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group may have a substituent. That is, some or all of the hydrogen atoms of the monovalent hydrocarbon group of R ¹ may be substituted with a substituent. The substituent is preferably a halogen atom, more preferably a fluorine atom.
R ¹ is preferably a methyl group, an ethyl group, a hexyl group, a decyl group, a phenyl group, or a trifluoropropyl group. When two or more R < ¹ > exists in a compound (1), it is preferable that several R < ¹ > is mutually the same from the point of the supply property of a raw material. However, several R < ¹ > may mutually differ.
R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably a methyl group or an ethyl group, and particularly preferably a methyl group. When ^two or more R < ² > exists in a compound (1), it is preferable that several R < ² > is mutually the same from the point which the reactivity of an alkoxy group becomes the same and it is easy to form a coating film uniformly. However, several R < ² > may mutually differ.
K in the compound (1) is an integer of 2 to 4, and 3 or 4 is preferable.

Specific examples of the compound (1) include, for example, tetrafunctional alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane; methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxy Trifunctional alkoxysilanes such as silane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane; dimethyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, etc. Bifunctional alkoxysilane etc. are mentioned. Of these, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and phenyltrimethoxysilane are preferable from the viewpoint of curing speed and physical properties of the resulting cured coating film.
Organosilane may be used individually by 1 type, and may use 2 or more types together.

Compound (1) may be used as a partially hydrolyzed condensate obtained by partial hydrolysis and condensation. The partially hydrolyzed condensate is a compound obtained by condensing the compound (1) by partial hydrolysis so that two or more hydrolyzable groups (—OR ² groups) remain in the molecule. It is. Although the overall structure of the partially hydrolyzed condensate is not clear, it is a polysilicate ester composed of a skeleton composed of —Si—O— bonds and an alkoxy group, and the skeleton may be linear or branched. It may be a chain or a cyclic structure.
The partially hydrolyzed condensate of compound (1) is more preferable as the degree of condensation is lower. The lower the degree of condensation of the partially hydrolyzed condensate, the better the compatibility with the resin component. Moreover, the thermal expansion coefficient of the cured coating film to be formed and the base material layer (reflection layer, etc.) on which the cured coating film is formed are closer, and the cured coating film substrate is caused by expansion and contraction due to heat. Peeling from the surface becomes difficult to occur.

  The method for producing the partially hydrolyzed condensate of compound (1) is not particularly limited, and known methods for producing partially hydrolyzed condensates can be employed. For example, the method of adding at least 1 sort (s) of water, an acid, and a solvent to a compound (1), and making it partially hydrolyze-condensate is mentioned.

As the partially hydrolyzed condensate of compound (1), those having different condensation degrees, structures and types of alkoxy groups are commercially available. For example, trade names “KR-500”, “KR-510”, “KR— “213” (manufactured by Shin-Etsu Chemical Co., Ltd.), trade names “MKC silicate MS51”, “MKC silicate MS56” (manufactured by Mitsubishi Chemical Corporation), trade names “M silicate 51”, “ethyl silicate 40”, “ethyl” Condensates having an effective silica content of about 28 to 70% by mass, such as silicate 45 (manufactured by Tama Chemical Co., Ltd.); trade names “HAS-1”, “HAS-” obtained by dissolving the condensates in ethanol or isopropanol 6 "," HAS-10 "(manufactured by Colcoat Co., Ltd.) and the like. The “effective silica content” is a value indicating the content of silica in terms of SiO ₂ when the polyalkyl silicate contained in the product is 100% by mass.
The partial hydrolysis-condensation product of compound (1) may be used individually by 1 type, and may use 2 or more types together.

  1.0-150.0 mass parts is preferable with respect to 100 mass parts of resin components, and, as for content of the hardening | curing agent in a 1st coating material, 5.0-100.0 mass parts is more preferable. If it is more than the said lower limit of content of a hardening | curing agent, it will be easy to bridge | crosslink a resin component fully. Moreover, if content of a hardening | curing agent is below the said upper limit, it will be easy to suppress that an unreacted hardening | curing agent remains in a cured coating film and exerts a bad influence on the performance of a cured coating film.

The first paint preferably contains a curing catalyst for the purpose of accelerating the curing reaction and imparting good chemical performance and physical performance to the first cured coating film 16 that is a cured product. In particular, when curing at a low temperature in a short time, it is preferable to contain a curing catalyst.
As the curing catalyst, for example, when an amine catalyst is used, at least one amine catalyst selected from the group consisting of aromatic amine, aliphatic amine, amide polyamine, polyamide, imidazole, aminotriazole, and dicyandiamide is preferable.
When a blocked isocyanate curing agent is used as the curing agent, at least one Lewis acid catalyst selected from the group consisting of tin octylate, tributyltin dilaurate, and dibutyltin dilaurate is preferred.
When an amino resin is used as the curing agent, a blocked acid catalyst is preferred. As the blocked acid catalyst, at least one Bronsted acid catalyst selected from the group consisting of carboxylate, sulfonate, and phosphate is preferable. Examples of the salt include amine salts. Further, higher alkyl-substituted sulfonic acid amine salts such as diethanolamine salt of dodecylbenzenesulfonic acid and triethylamine salt are also preferable.
When organosilane is used as the curing agent, acidic phosphoric acid esters such as phosphoric acid monoesters and phosphoric acid diesters; acidic boric acid esters such as boric acid monoesters and boric acid diesters, and the like.
The curing catalyst contained in the first paint may be one type or two or more types.

  As for content of the curing catalyst in a 1st coating material, 0.0001-10.0 mass parts is preferable with respect to 100 mass parts of total amounts of solid content other than a pigment. If the content of the curing catalyst is 0.0001 parts by mass or more, the catalytic effect can be sufficiently obtained. When the content of the curing catalyst is 10.0 parts by mass or less, the remaining curing catalyst hardly affects the first cured coating film 16 and heat resistance and water resistance are improved.

The solvent contained in the first paint is not particularly limited as long as each component of the first paint can be dissolved or dispersed. For example, there is no particular limitation, and aromatic compounds such as xylene and toluene; carbonyl compounds such as methyl ethyl ketone and methyl isobutyl ketone; acetates such as butyl acetate and amyl acetate; propylene glycol alkyl ethers such as propylene glycol monomethyl ether; Can be mentioned.
1 type may be sufficient as the solvent contained in a 1st coating material, and 2 or more types may be sufficient as it.

  3-60 mass% is preferable and, as for content of the solvent in a 1st coating material (100 mass%), 5-40 are more preferable. If content of a solvent is more than the said lower limit, the viscosity of a 1st coating material will not become high too much, but a coating-film external appearance will improve. Moreover, if content of a solvent is below the said upper limit, a foaming trace will be hard to generate | occur | produce in the 2nd cured coating film 18 at a hardening process.

The yield value of the first paint is preferably 0.5 to 5.0 Pa, and more preferably 0.7 to 3.0 Pa. When the yield value of the first paint is equal to or more than the lower limit value, the first paint is less likely to sneak into the glass surface, and the glass edge portion is easily coated appropriately. If the yield value of a 1st coating material is below the said upper limit, it will become easy to apply a 1st coating material uniformly.
The yield value of the paint in the present invention was determined by measuring the shear rate and shear stress at 25 ° C. using a rotational viscometer, and extrapolating the shear rate to zero by the Casson plot of the shear rate and shear stress. It is obtained as the value of shear stress.

The yield value of the first paint is preferably adjusted with a rheology control agent.
Examples of the rheology control agent include fatty acid amide, bentonite, organically modified bentonite, long chain fatty acid ester, urea wax, polyolefin wax, polyethylene oxide, and microgel. Of these, fatty acid amides are preferred because they swell easily with solvents such as aromatics, ketones, and esters, and the yield value of the paint can be adjusted with a small amount of addition.
Rheology control agents are trade name “Tarren” or trade name “Flownon” (both manufactured by Kyoeisha Chemical Co., Ltd.), trade name “Disparon” (manufactured by Enomoto Kasei Co., Ltd.), trade name “CERAFAK” (manufactured by BYK-Chemie), It is marketed under a trade name such as trade name “BENTONE” (manufactured by RHEOX).
The rheology control agent contained in the first paint may be one type or two or more types.

When the first paint contains a rheology control agent, the content of the rheology control agent is preferably 0.05 to 15.0% by mass in the first paint (100% by mass), and 0.1 to 10.0. % By mass is more preferable, and 0.3 to 7.0% by mass is more preferable. If the content of the rheology control agent is not less than the lower limit, the required yield value can be sufficiently expressed. If content of a rheology control agent is below the said upper limit, the viscosity of a 1st coating material will not become high too much, but a coating-film external appearance will improve.
Examples of the method of blending the rheology control agent include a method in which the resin component, a solvent, a pigment and the like are added to the main component of the paint and then dispersed or stirred with a kneader, a disperser or the like.

  Moreover, you may mix | blend other additives other than the said hardening | curing agent, a curing catalyst, and a rheology control agent with the 1st coating material suitably according to the objective. Other additives include light stabilizers such as hindered amine light stabilizers; organic ultraviolet absorbers such as benzophenone compounds, benzotriazole compounds, triazine compounds, and cyanoacrylate compounds; zinc oxide, cerium oxide, and the like Inorganic UV absorbers; Matting agents such as ultrafine synthetic silica; Nonionic, cationic or anionic surfactants; Leveling agents; Fillers; Thermal stabilizers; Thickeners; Dispersants; Agents; and the like.

  1.1-2.0 are preferable and, as for the specific gravity of a 1st coating material, 1.2-1.5 are more preferable. When the specific gravity of the first paint is equal to or higher than the lower limit value, the curtain flow property is good in application by the curtain flow coating method, and it is easy to suppress the occurrence of curtain breakage and pinholes. Further, if the specific gravity of the first paint is not more than the above upper limit value, the coating unevenness is small and a uniform film thickness is easily obtained.

  A 1st coating material can be manufactured using the various apparatuses used for normal coating, such as a ball mill, a paint shaker, a sand mill, a jet mill, a rocking mill, an attritor, a three roll, a kneader.

After the first coating layer 16A is formed in the first coating step, preheating may be performed at a temperature lower than the curing temperature of the first coating layer 16A before the second coating step. By performing preheating, the low volatile components in the first coating layer 16A are volatilized and the yield value of the first coating layer 16A is increased, so when applying the second paint in the second coating step, The second coating material is less likely to be mixed into one coating layer 16A. In addition, when the uncured first coating layer 16A and the second coating layer 18A are simultaneously cured in the curing step, the multi-layer coating film caused by the low volatile components in the first cured coating film 16 is removed. It becomes easy to suppress.
The preheat temperature is preferably 40 to 110 ° C, more preferably 50 to 100 ° C.
The preheating time is preferably 5 seconds to 10 minutes, more preferably 10 seconds to 5 minutes.

[Second application step]
As shown in FIG. 2, the second coating layer 18A is coated on the uncured first coating layer 16A and the difference in curing temperature from the first coating layer 16A is within 30 ° C. Form.
Examples of the method for applying the second paint include a method using a brush, a roller, a spray, a flow coater, an applicator and the like. Among these, from the viewpoint of productivity of the mirror 10 and ease of controlling the film thickness of the second cured coating film 18, application with a flow coater is preferable, and curtain flow coating is particularly preferable.

  5-60 micrometers is preferable and, as for the dry film thickness of 18 A of 2nd coating layers, 10-50 micrometers is more preferable. If the film thickness of the second coating layer 18A is equal to or greater than the lower limit value, the base concealing property can be sufficiently obtained, and the coating layer made of the first coating layer 16A can be easily protected from ultraviolet rays. Moreover, if the film thickness of the second coating layer 18A is equal to or less than the upper limit value, it is easy to suppress the occurrence of defects such as cracks or sagging during coating.

The curing temperature of the second coating layer 18A, that is, the temperature at which the curing reaction of the second coating layer 18A proceeds is preferably 180 ° C. or less, and preferably 30 to 150 ° C. If the curing temperature of the second coating layer 18A is equal to or higher than the lower limit value, it is difficult for a trace of unreacted material from the first coating layer 16A and foaming marks of the coating film due to the diluting solvent to occur. If the curing temperature of the second coating layer 18A is equal to or lower than the upper limit, it is difficult for the coating film to be poorly cured in the winter production line.
The curing temperature of the second coating layer 18A can be adjusted as appropriate by selecting the type of fluoroolefin copolymer, curing agent, and curing catalyst described later, that is, the curing system.

The difference between the curing temperature of the first coating layer 16A and the curing temperature of the second coating layer 18A is within 30 ° C. Thereby, it can suppress that a crack arises in the 1st cured coating film 16 and the 2nd cured coating film 18 which are formed.
As described above, conventionally, when a cured coating film is formed on a glass substrate by the 2-coat 1-bake method, cracks may occur in the cured coating film. This problem is considered to be caused by a difference in curing speed between the first coating layer and the second coating layer and a difference in curing shrinkage when heated in the curing step. Generally, heating during curing is performed from the opposite side of the coating layer on the substrate. Since glass has a lower thermal conductivity than metal, the temperature of the coating layer on the glass substrate due to heating is gentler than that of the coating layer on the metal plate. Therefore, if there is a difference between the curing temperature of the first coating layer and the curing temperature of the second coating layer, the coating layer with the lower curing temperature cures faster, and the curing shrinkage between the coating layers during the curing. It is considered that there is a difference between the two and cracks are generated.
On the other hand, in the present invention, the difference between the curing temperatures of the first coating layer 16A and the second coating layer 18A is within 30 ° C., so that even if the temperature rise due to heating becomes moderate, the first coating layer The curing of the layer 16A and the curing of the second coating layer 18A proceed to the same extent. Therefore, the curing shrinkage between the respective coating layers is equivalent, so that the occurrence of cracks in the cured coating film can be suppressed.

  The difference in the curing temperature between the first coating layer 16A and the second coating layer 18A is preferably within 30 ° C, more preferably within 20 ° C because it is easy to suppress the occurrence of cracks in the cured coating film.

  As a mode in which the difference between the curing temperature of the first coating layer 16A and the curing temperature of the second coating layer 18A is within 30 ° C., a mode in which the first coating and the second coating are the same curing system is preferable. That is, it is preferable that the crosslinking reaction at the time of curing in the first paint and the second paint be the same kind of reaction. Specifically, it is preferable that the same kind of curing agent is contained in the first paint and the second paint.

(Second paint)
As the second paint, for example, a fluoroolefin copolymer (hereinafter referred to as “copolymer (A)”) and a solvent are included as essential components, and if necessary, pigments, curing agents, curing catalysts, rheology. Examples thereof include coating compositions containing other components such as a control agent. Since the second paint contains the copolymer (A), the second cured coating film 18 having excellent weather resistance is formed.

The copolymer (A) is a copolymer of a fluoroolefin and another monomer copolymerizable with the fluoroolefin.
A fluoroolefin is a compound in which one or more hydrogen atoms of an olefin hydrocarbon (general formula C _n H _2n ) are substituted with fluorine atoms.
2-8 are preferable and, as for carbon number of a fluoro olefin, 2-6 are more preferable.
The number of fluorine atoms in the fluoroolefin (hereinafter referred to as “fluorine addition number”) is preferably 2 or more, and more preferably 3 or 4. When the fluorine addition number is 2 or more, the weather resistance of the second cured coating film 18 is improved. In the fluoroolefin, one or more hydrogen atoms not substituted with fluorine atoms may be substituted with chlorine atoms.
A fluoro olefin may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the fluoroolefin, at least one selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinylidene fluoride and vinyl fluoride is preferable, and tetrafluoroethylene and chlorotrifluoroethylene are more preferable.

  The lower limit of the ratio of the polymer units based on the fluoroolefin in the copolymer (A) is from the point of giving sufficient weather resistance to the second cured coating film 18 to all units contained in the copolymer (A). On the other hand, 20 mol% is preferable and 30 mol% is more preferable. In addition, the upper limit of the ratio of the polymer units based on the fluoroolefin is preferably 80 mol%, more preferably 70 mol%, from the viewpoint of adhesion with the first cured coating film 16.

  The other monomer is preferably a vinyl monomer, that is, a compound having a carbon-carbon double bond. Examples of vinyl monomers include vinyl ether, allyl ether, carboxylic acid vinyl ester, carboxylic acid allyl ester, and olefin.

Examples of the vinyl ether include cycloalkyl vinyl ethers such as cyclohexyl vinyl ether; alkyl vinyl ethers such as nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, and t-butyl vinyl ether;
Examples of allyl ethers include alkyl allyl ethers such as ethyl allyl ether and hexyl allyl ether.

Examples of the carboxylic acid vinyl ester or carboxylic acid allyl ester include vinyl esters or allyl esters of carboxylic acids such as acetic acid, butyric acid, pivalic acid, benzoic acid, and propionic acid. Moreover, as a vinyl ester of a carboxylic acid having a branched alkyl group, commercially available Veova-9, Veova-10 (both manufactured by Shell Chemical Co., Ltd., trade names) and the like may be used.
Examples of olefins include ethylene, propylene, isobutylene and the like.
The said other monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

Moreover, it is preferable that a copolymer (A) has a crosslinkable group which gives a curing reactive site | part from the point which the adhesiveness of the 1st cured coating film 16 and the 2nd cured coating film 18 improves. That is, it is preferable to have crosslinkable groups that react with each other or with a curing agent to form a crosslink. Examples of the crosslinkable group include a hydroxyl group, a carboxyl group, a hydrolyzable silyl group, an oxetanyl group, an epoxy group, and an amino group. Among these, a hydroxyl group is preferable because the adhesion between the first cured coating film 16 and the second cured coating film 18 is more excellent.
Examples of the method of introducing the crosslinkable group include a method of copolymerizing the monomer having the crosslinkable group.

Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether; hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether; hydroxyethyl carboxylic acid Examples thereof include hydroxyalkyl vinyl esters such as vinyl esters; (meth) acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth) acrylate.
Examples of the monomer having a carboxyl group include crotonic acid and undecenoic acid.
Examples of the monomer having a hydrolyzable silyl group include triethoxyvinylsilane.
Examples of the monomer having an oxetanyl group include 3-ethyl-3-vinyloxymethyloxetane and 3-methyl-3-methacryloylmethyloxetane.
Examples of the monomer having an epoxy group include glycidyl vinyl ether and glycidyl allyl ether.
Examples of the monomer having an amino group include aminopropyl vinyl ether and aminopropyl vinyl ester.

  Moreover, the copolymer (A) which has a crosslinkable group is obtained also by the method of introduce | transducing a crosslinkable group by the post reaction after superposition | polymerization. For example, a method of introducing a hydroxyl group by saponifying a polymer obtained by copolymerizing a carboxylic acid vinyl ester, a polymer obtained by copolymerizing a monomer having a hydroxyl group with a polyvalent carboxylic acid or its anhydride A method of introducing a carboxyl group by reacting a product, a method of introducing a hydrolyzable silyl group by reacting an isocyanate alkylalkoxysilane with a polymer obtained by copolymerizing a monomer having a hydroxyl group, and a group having a hydroxyl group. Examples thereof include a method of introducing an isocyanate group by reacting a polyvalent isocyanate compound with a polymer obtained by copolymerizing a monomer.

When the copolymer (A) has a hydroxyl group, the lower limit of the hydroxyl value is preferably 5 mgKOH / g-resin because the adhesion between the first cured coating film 16 and the second cured coating film 18 is improved. 10 mg KOH / g-resin is more preferred. Further, the upper limit of the hydroxyl value is preferably 250 mgKOH / g-resin, more preferably 200 mgKOH / g-resin because the elongation percentage of the second cured coating film 18 becomes higher and peeling and cracking are less likely to occur. .
In addition, the hydroxyl value (unit: mgKOH / g-resin) of the copolymer (A) in the present invention is the hydroxyl value in a state in which the copolymer (A) does not contain a solvent, that is, a nonvolatile content of 100% by mass. Means.

  The number average molecular weight of the copolymer (A) is preferably from 2,000 to 100,000, more preferably from 6,000 to 30,000. If the number average molecular weight of a copolymer (A) is more than the said lower limit, the water resistance of a coating film and salt water resistance will become favorable. If the number average molecular weight of a copolymer (A) is below the said upper limit, the smoothness of a coating film will become favorable.

As copolymer (A), chlorotrifluoroethylene (CTFE), cyclohexyl vinyl ether (CHVE), a copolymer of alkyl vinyl ether and hydroxyalkyl vinyl ether; a copolymer of CTFE, alkyl vinyl ether and allyl alcohol; CTFE, aliphatic A copolymer of carboxylic acid vinyl ester and hydroxyalkyl vinyl ether; or a copolymer using tetrafluoroethylene in place of CTFE in these copolymers is preferred.
These are the product name “Lumiflon” (Asahi Glass Co., Ltd.), the product name “Fluonate” (Dainippon Ink Chemical Co., Ltd.), the product name “Cefral Coat” (Central Glass Co., Ltd.), and the product name “Zaflon” (Toa Gosei Co., Ltd.) Product name) such as “Zefle” (manufactured by Daikin Industries, Ltd.).
The copolymer (A) contained in the second paint may be one type or two or more types.

  The content of the copolymer (A) in the second paint is preferably 1.0 to 70.0% by mass, and 3.0 to 60.0% by mass in the second paint (100% by mass). More preferred. If content of a copolymer (A) is more than the said lower limit, the weather resistance of the 2nd cured coating film 18 will improve. If content of a copolymer (A) is below the said upper limit, it will become easy to apply | coat a 2nd coating material uniformly.

When the copolymer (A) does not have a crosslinkable group that provides self-curing properties, the second coating material preferably contains a curing agent. Any curing agent may be used as long as it can react with the crosslinkable group of the copolymer (A) to form a cured coating film, and various curing agents known as coating curing agents can be used. Specific examples of these curing agents are the same as those mentioned in the first paint. The curing agent is preferably at least one selected from the group consisting of blocked isocyanate curing agents, amino resins and organosilanes.
1 type may be sufficient as the hardening | curing agent contained in a 2nd coating material, and 2 or more types may be sufficient as it.

  In the manufacturing method of this invention, it is preferable that a 1st coating material and a 2nd coating material are the same hardening systems from the point which suppresses that a crack arises in a cured coating film. That is, it is preferable that the cross-linking reaction at the time of curing in the first paint and the second paint is the same kind of reaction. In the present invention, it is preferable that the first coating material and the second coating material contain the same type of curing agent. In both the first coating material and the second coating material, a blocked isocyanate curing agent, an amino resin, and More preferably, the same kind of curing agent selected from the group consisting of organosilanes is included.

  As for content of the hardening | curing agent in a 2nd coating material, 1.0-60.0 mass parts is preferable with respect to 100 mass parts of copolymers (A), and 5.0-50.0 mass parts is more preferable. . If content of a hardening | curing agent is more than the said lower limit, it will be easy to bridge | crosslink a copolymer (A) fully. If content of a hardening | curing agent is below the said upper limit, it will be easy to suppress that an unreacted hardening | curing agent remains in the 2nd hardening coating film 18, and affects the performance of a coating film.

The solvent contained in the second paint is not particularly limited, but is an aromatic compound such as xylene or toluene; a carbonyl compound such as methyl ethyl ketone or methyl isobutyl ketone; an acetate such as butyl acetate or amyl acetate; propylene glycol monomethyl ether Propylene glycol alkyl ethers such as;
The solvent contained in the second paint may be one kind or two or more kinds.

  5.0-80.0 mass% is preferable and, as for content of the solvent contained in a 2nd coating material (100 mass%), 10.0-60.0 mass% is more preferable. If the content of the solvent is not less than the lower limit, the viscosity of the second paint tends to be sufficiently low, and the coating operation becomes easy. If the content of the solvent is not more than the above upper limit value, it is easy to remove the solvent and form the second cured coating film 18.

The second paint preferably contains a pigment for the purpose of rust prevention, coloring, reinforcement and the like. The pigment is preferably at least one pigment selected from the group consisting of rust preventive pigments, colored pigments and extender pigments. Examples of the rust preventive pigment, the color pigment, and the extender pigment are the same as those described for the first paint, and preferred embodiments are also the same.
The pigment contained in the first paint and the pigment contained in the second paint may be the same or different.

  The content of the pigment in the second paint is preferably 1.0 to 70.0% by weight, and more preferably 3.0 to 60.0% by weight in the second paint (100% by weight). If the pigment content is not less than the lower limit, the pigment function is easily obtained. If the pigment content is less than or equal to the above upper limit value, the second cured coating film 18 is unlikely to be cracked or damaged by the impact of sand or the like, and the coating film does not easily peel off over time.

The second coating material preferably contains a curing catalyst for the purpose of accelerating the curing reaction and imparting good chemical performance and physical performance to the second cured coating film 18. In particular, when curing at a low temperature in a short time, it is preferable to contain a curing catalyst. Examples of the curing catalyst include the same ones as those mentioned in the first paint, and the preferred embodiments are also the same. The curing catalyst contained in the second paint may be one type or two or more types. May be.

  As for content of the curing catalyst in a 2nd coating material, 0.00001-10 mass parts is preferable with respect to 100 mass parts of total amounts of solid content other than a pigment. If the content of the curing catalyst is 0.00001 part by mass or more, the catalytic effect can be sufficiently obtained. When the content of the curing catalyst is 10 parts by mass or less, the remaining curing catalyst hardly affects the second cured coating film 18 and heat resistance and water resistance are improved.

  The yield value of the second paint is preferably 0.5 to 5.0 Pa, more preferably 0.7 to 3.0 Pa. If the yield value of the second paint is equal to or greater than the lower limit value, the second paint is less likely to sneak into the glass surface, and the glass edge portion is easily coated appropriately. If the yield value of the second paint is not more than the upper limit value, the second paint can be easily applied uniformly on the first coating layer 16A.

The yield value of the second paint is preferably adjusted with a rheology control agent.
Examples of the rheology control agent contained in the second paint include the same ones as those mentioned for the first paint, and preferred embodiments are also the same.
The rheology control agent contained in the second paint may be one kind or two or more kinds.

When the second paint contains a rheology control agent, the content of the rheology control agent is preferably 0.05 to 15.0% by mass in the second paint (100% by mass), and 0.1 to 10.0. % By mass is more preferable, and 0.3 to 7.0% by mass is more preferable. If the rheology control agent is equal to or more than the lower limit value, the required yield value is easily developed. Moreover, if a rheology control agent is below the said upper limit, the viscosity of a 2nd coating material will not become high too much, but a coating-film external appearance will improve.
As a method for blending the rheology control agent, there is a method in which the copolymer (A), a solvent, a pigment and the like are added to the main component of the coating material and then dispersed or stirred by a kneader, a disperser or the like.

Moreover, you may mix | blend other additives other than the said hardening | curing agent, a curing catalyst, and a rheology control agent with the 2nd coating material suitably according to the objective.
As the curing catalyst, any of the amine catalyst, Bronsted acid catalyst and Lewis acid catalyst mentioned in the first paint is preferable. In the present invention, cracks are less likely to occur in the formed cured coating film, and therefore the first paint and the second paint are each selected from the group consisting of aromatic amines, aliphatic amines, amide polyamines, and polyamides. At least one Bronsted acid catalyst selected from the group consisting of at least one amine catalyst, carboxylate, sulfonate, phosphate, or a group consisting of tin octylate, tributyltin dilaurate, dibutyltin dilaurate It is preferable to contain at least one Lewis acid catalyst selected from
It is preferable that the curing catalyst in the first paint and the curing catalyst in the second paint do not interact. Specifically, when the curing catalyst in the first paint is an amine catalyst, the curing catalyst in the second paint is particularly preferably an amine catalyst or a Lewis acid catalyst.

Examples of the additive include those listed as other additives in the first paint. In addition, since a large amount of an inorganic material is blended in the first coating material, silane is added to the second coating material for the purpose of improving the adhesion between the first cured coating film 16 and the second cured coating film 18. A coupling agent may be blended.
Examples of the silane coupling agent include a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, a vinyl group, an amino group, a (meth) acryloyl group, a styryl group, a mercapto group, and an isocyanate group. It is done. Of these, a silane coupling agent having an epoxy group is preferable.

  The specific gravity of the second paint is preferably 1.1 to 2.0, and more preferably 1.2 to 1.5. If the specific gravity of the second paint is equal to or higher than the lower limit value, the curtain flow property is good, and it is easy to suppress the occurrence of curtain breakage and pinholes. Further, if the specific gravity of the second paint is not more than the above upper limit value, the coating unevenness is small and a uniform film thickness is easily obtained.

  A 2nd coating material can be manufactured using the various apparatuses used for normal coating, such as a ball mill, a paint shaker, a sand mill, a jet mill, a rocking mill, an attritor, a three roll, a kneader.

[Curing process]
The first coating layer 16A and the second coating layer 18A are heated to cure the first coating layer 16A and the second coating layer 18A at the same time, as shown in FIG. 16 and the 2nd cured coating film 18 are formed, and the mirror 10 is obtained.
The heating temperature in the curing step may be a temperature at which the curing reaction of the first coating layer 16A and the second coating layer 18A proceeds, is preferably 200 ° C. or less, and more preferably 120 to 200 ° C. When the heating temperature is 120 ° C. or higher, the first coating layer 16A and the second coating layer 18A are sufficiently cross-linked, and a tough multilayer coating film is easily obtained. Further, if the heating temperature is 200 ° C. or less, poor appearance due to the difference in the degree of curing shrinkage between the first coating layer 16A and the second coating layer 18A is unlikely to occur.
Although heating time changes also with heating temperature, when heating temperature is 120-200 degreeC, 10 second-5 minutes are preferable.

  The heating method of the first coating layer 16A and the second coating layer 18A is not particularly limited, and examples thereof include a sealed curing furnace and a tunnel furnace capable of continuous curing. The heating source is not particularly limited and can be performed by a method such as hot air circulation, infrared heating, high-frequency heating or the like. Of these, from the viewpoint of continuous productivity, a tunnel furnace, hot air circulation and infrared heating are preferred from the viewpoint of uniform heat transfer and uniform cured coating.

  15-160 micrometers is preferable and, as for the total film thickness of the multilayer coating film which match | combined the 1st cured coating film 16 and the 2nd cured coating film 18, 30-100 micrometers is more preferable. If the total film thickness is equal to or greater than the lower limit value, the anti-rust effect of the reflective layer 14 is easily exerted, and the decrease in the reflectance of the mirror 10 is easily suppressed. If the total film thickness is equal to or less than the upper limit value, the multilayer coating film is difficult to peel from the reflective layer 14 or the metal protective layer.

According to the mirror manufacturing method of the present invention described above, the difference in curing temperature between the first coating layer and the second coating layer is within 30 ° C. The difference in curing shrinkage between the two coating layers can be reduced. Therefore, a mirror having a cured coating film without cracks can be stably produced by the 2-coat 1-bake method.
In addition, the mirror obtained by the method for manufacturing a mirror of the present invention has particularly excellent durability particularly when the copolymer (A) is contained in the second cured coating film as in the case of the mirror 10. The solar heat collecting system that collects solar heat and uses it as thermal energy is preferably used as a mirror for reflecting sunlight (a solar heat collecting reflector).
In addition, the manufacturing method of the mirror of this invention is not limited to the method mentioned above.
Moreover, the manufacturing method of the coated article of this invention is not limited to the manufacturing method of the said mirror.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited by the following description.
Examples 1 to 7 are production examples, and Examples 8 to 11 are examples.
<Production of copolymer (A)>
[Example 1]
In a pressure resistant reactor with a stainless steel stirrer having an internal volume of 2500 mL, 590 g of xylene, 170 g of ethanol, 129 g of 4-hydroxybutyl vinyl ether (HBVE), 206 g of ethyl vinyl ether (EVE) and cyclohexyl vinyl ether (CHVE) 208 g, 11 g of calcium carbonate, and 3.5 g of perbutyl perpivalate (PBPV) were charged, and dissolved oxygen in the liquid was removed by deaeration with nitrogen.
Next, 660 g of fluoroolefin, chlorotrifluoroethylene (CTFE), was introduced, the temperature was gradually raised, and the reaction was continued while maintaining the temperature at 65 ° C. After reacting for 10 hours, the reaction was stopped by cooling the reactor with water. After cooling the reaction solution to room temperature, unreacted monomers were purged, and the resulting reaction solution was filtered through diatomaceous earth to remove solids. Next, a part of xylene and ethanol were removed by distillation under reduced pressure to obtain a xylene solution of copolymer (A) (nonvolatile content: 60% by mass).
It was 51.1 mgKOH / g-resin when the hydroxyl value of the obtained copolymer (A) was measured.

<Manufacture of second paint (α) (fluorine-containing paint)> (curing agent: melamine resin)
[Example 2]
To 16.7 g of the xylene solution of the copolymer (A) obtained in Example 1 (nonvolatile content: 60% by mass), 40. of titanium oxide (trade name “D-918”, manufactured by Sakai Chemical Co., Ltd.) as a pigment. 0 g, 20.0 g of xylene and 23.2 g of butyl acetate were added, and 100.0 g of glass beads having a diameter of 1 mm were further added, and the mixture was stirred for 2 hours with a paint shaker. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, to 31.4 g of the pigment composition, 44.0 g of the xylene solution of the copolymer (A) (nonvolatile content: 60% by mass) and a methylated melamine resin (made by Mitsui Cytec, 8.1 g of trade name “Cymel 303”, 12.2 g of butyl alcohol, 3.5 g of butyl acetate, and p-toluenesulfonic acid solution neutralized with an amine compound as a curing catalyst (manufactured by Mitsui Cytec) Further, 0.8 g of a trade name “Catalyst 602”) was further added and mixed to obtain a second paint (α).
It was 1.17 when the specific gravity of the 2nd coating material ((alpha)) was measured based on "JISK5600-2-4".
When the shear rate and shear stress were measured in an environment of 25 ° C. using an E-type viscometer, and the yield value of the second paint (α) was determined by Casson plot of shear rate and shear stress, 31.

<Production of second paint (β) (fluorine-containing paint)> (Curing agent: blocked isocyanate)
[Example 3]
A pigment composition was obtained in the same manner as in Example 2.
Next, 34.0 g of the pigment composition was mixed with 44.0 g of a xylene solution of the copolymer (A) obtained in Example 1 (nonvolatile content: 60% by mass) and a blocked isocyanate resin (Sumitomo) as a curing agent. Bayer Urethane Co., Ltd., trade name “Sumijour BL3175”) 10.2 g, butyl acetate 12.6 g, and curing catalyst dibutyltin dilaurate (diluted 4-10 times with xylene to 1.8 g) And a second paint (β) was obtained.
The specific gravity of the second paint (β) was measured according to “JIS K 5600-2-4” and found to be 1.16.
Using an E-type viscometer, the shear rate and shear stress were measured in an environment of 25 ° C., and the yield value of the second paint (β) was determined by the Casson plot of shear rate and shear stress. 32.

<Manufacture of second paint (γ) (fluorine-containing paint)> (curing agent: melamine resin)
[Example 4]
A pigment composition was obtained in the same manner as in Example 2.
Next, 24.0 g of the xylene solution of the copolymer (A) obtained in Example 1 (non-volatile content: 60% by mass), 51.4 g of the pigment composition, and a methylated melamine resin (Mitsui) as a curing agent were used. P-toluenesulfonic acid solution neutralized with 8.1 g of Cytec Co., Ltd. (trade name “Cymel 303”), 12.2 g of butyl alcohol, 3.5 g of butyl acetate, and an amine compound as a curing catalyst ( 0.8 g of Mitsui Cytec Co., Ltd., trade name “Catalyst 602”) was further added and mixed to obtain a second paint (γ).
The specific gravity of the second paint (γ) was measured according to “JIS K 5600-2-4” and found to be 1.25.
When the shear rate and shear stress were measured in an environment of 25 ° C. using an E-type viscometer, and the yield value of the second coating material (γ) was determined by the Casson plot of shear rate and shear stress, 51.

<Manufacture of second paint (δ) (fluorine-containing paint)> (Curing agent: Melamine resin)
[Example 5]
A pigment composition was obtained in the same manner as in Example 2.
Next, 24.0 g of the xylene solution of the copolymer (A) obtained in Example 1 (non-volatile content: 60% by mass), 51.4 g of the pigment composition, and a methylated melamine resin (Mitsui) as a curing agent were used. 8.1 g of Cytec Co., Ltd., trade name “Cymel 303”, 2.1 g of fatty acid amide rheology control agent (Kyoeisha Chemical Co., Ltd., trade name “Flownon SP-1000”), and 10.1 g of butyl alcohol. Further, 3.5 g of butyl acetate and 0.8 g of a p-toluenesulfonic acid solution (trade name “Catalyst 602” manufactured by Mitsui Cytec Co., Ltd.) neutralized with an amine compound as a curing catalyst were added and mixed. As a result, a second paint (δ) was obtained.
Based on “JIS K 5600-2-4”, the specific gravity of the second paint (δ) was measured and found to be 1.25.
Using an E-type viscometer, the shear rate and shear stress were measured in an environment of 25 ° C., and the yield value of the second paint (δ) was determined by the Casson plot of shear rate and shear stress. 91.

<Manufacture of first paint (ε) (rust preventive paint)> (curing agent: amine)
[Example 6]
Lead-free modified epoxy resin paint main agent (Dainippon Paint Co., Ltd., trade name “SM COAT DF LEAD FREE”) and modified epoxy resin paint curing agent (Dainippon Paint Co., Ltd., trade name) 15.5 g of “SM COAT DF curing agent”) was mixed until uniform at room temperature to obtain a first paint (ε).
Main agent for modified epoxy resin paint (Dainippon Paint Co., Ltd., trade name “SM COAT DF LEAD FREE”) is 17.0 g zinc oxide, 17.0 g ferric oxide, 16.6 g epoxy resin, low boiling aromatic It consists of 15.0 g of naphtha, 10.0 g of carbon black, 10.0 g of ethylene glycol monobutyl ether, 1.5 g of 1,3,5-triethylbenzene, 11.0 g of xylene and 1.9 g of ethylbenzene.
Based on “JIS K 5600-2-4”, the specific gravity of the first paint (ε) was measured and found to be 1.25.
Using an E-type viscometer, the shear rate and shear stress were measured in an environment of 25 ° C., and the yield value of the first paint (ε) was determined by Casson plot of shear rate and shear stress. It was 97 Pa.

<Manufacture of first paint (μ) (rust preventive paint)> (curing agent: melamine resin)
[Example 7]
32.0 g of alkyd resin (made by Hitachi Chemical Co., Ltd., trade name “Phtalkid 213-60”) and basic cyanamide zinc calcium as a rust preventive pigment (trade name “LF Bosei ZK-S2” made by Kikuchi Color Co., Ltd.) , 13.6 g of extender talc (product name “LMR100”, manufactured by Fuji Talc Co., Ltd.), and extender barium sulfate (product name “Precipitated barium sulfate # 100 ”), 3.3 g of titanium oxide (trade name“ D-918 ”, manufactured by Sakai Chemical Co., Ltd.), a coloring pigment, 13.0 g of xylene, and 10.0 g of butyl alcohol In addition, 100.0 g of glass beads having a diameter of 1 mm were added, and the mixture was stirred for 2 hours with a paint shaker. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, 10.5 g of butylated melamine resin (manufactured by Hitachi Chemical Co., Ltd., trade name “Melan 265”) as a curing agent and 1.6 g of cobalt naphthenate solution as a desiccant are added to the pigment composition. Were further added and mixed to obtain a first paint (μ).
The specific gravity of the first paint (μ) was measured according to “JIS K 5600-2-4” and found to be 1.23.
When the shear rate and shear stress were measured in an environment of 25 ° C. using an E-type viscometer, and the yield value of the first coating material (μ) was determined by the Casson plot of shear rate and shear stress, 0. 96.

<Manufacture of mirrors>
[Example 8]
On one side of the glass substrate, a silver plating process is performed so that the thickness is 1000 mg / m ² to form a reflective layer (silver layer), and copper is plated on the reflective layer so that the thickness is 100 mg / m ^2. The metal protective layer (copper layer) was formed by processing. Next, on the metal protective layer, the first paint (ε) is applied with a curtain flow coater so that the film thickness of the dry coating film becomes 30 μm, and a first application layer is formed. For 5 minutes.
Next, on the first coating layer, the second coating (β) is applied by a curtain flow coater so that the film thickness of the dried coating film becomes 30 μm, and a second coating layer is formed, and 180 ° C. A first cured coating film (rust-preventing coating film) and a second cured coating film (fluorine-containing coating film) were formed by drying and curing in an oven for 5 minutes to obtain a mirror.

[Example 9]
A mirror was obtained in the same manner as in Example 8 except that the first paint (μ) was used instead of the first paint (ε).

[Example 10]
The same as Example 8 except that the second paint (γ) was used instead of the second paint (β), and the first paint (μ) was used instead of the first paint (ε). I got a mirror.

[Example 11]
The same as Example 8 except that the second paint (δ) was used instead of the second paint (β), and the first paint (μ) was used instead of the first paint (ε). I got a mirror.

[Curing temperature]
The curing temperatures of the first coating layer and the second coating layer in Examples 8 to 11 were measured by the method shown below.
Viscosity / viscoelasticity measuring device (manufactured by Eiko Seiki Co., Ltd., product name: viscosity / viscoelasticity measuring device “Leo Stress 6000”) is used to increase the viscosity at a temperature rising rate of 10 ° C./min. Was measured as the curing temperature.

<Evaluation method>
The coating on the mirrors of Examples 8 to 11 and the obtained mirrors were evaluated by the following methods.
(I) Painting 1. Curtain flow property During the coating of the second paint (fluorine-containing paint) with a curtain flow coater, whether or not curtain breakage or pinholes occurred was visually evaluated.
Evaluation was performed according to the following criteria.
○: No curtain breakage or pinhole was observed.
Δ: Some of the curtains and pinholes were confirmed.
X: Generation | occurrence | production of curtain cut and pinhole was confirmed.
2. The coating of the paint on the reflective surface After the second paint was applied with a curtain flow coater, whether or not the second paint was applied to the reflective surface side was evaluated by visual evaluation.
Evaluation was performed according to the following criteria.
(Double-circle): There is little wraparound to the reflective surface side of a 2nd coating material, and the edge is coated moderately.
○: There is a part of the wrap around the reflecting surface of the second paint.
(Triangle | delta): There are many surroundings to the reflective surface side of a 2nd coating material, and washing | cleaning of a reflective surface is required.

(Ii) Mirror 3. Curability The cured coating film surfaces of the mirrors obtained in Examples 8 to 11 were rubbed 100 times with gauze containing xylene, and the state of the cured coating film at that time was evaluated according to the following criteria.
A: There is no dissolution of the cured coating film.
○: Although there is no dissolution of the cured coating film, scratches occur.
Δ: A part of the cured coating film is dissolved.
X: The cured coating film is completely dissolved.
4). Adhesiveness Adhesiveness of the 1st cured coating film and the 2nd cured coating film was measured based on JISZ54008.5.
5. Abnormality of the cured coating film The mirror was cut, and the cross-section was observed with a scanning electron microscope, and evaluated according to the following criteria.
○: No cracks occurred in the first cured coating film (rust-preventing coating film) and the second cured coating film (fluorine-containing coating film).
X: A crack occurred in the first cured coating film (rust-preventing coating film) or the second cured coating film (fluorine-containing coating film).
<Measurement conditions>
Testing machine: “JSM-5900LV” manufactured by JEOL Ltd.,
Accelerating voltage: 20 kV,
Magnification: 1000 times
Pretreatment for measurement: Platinum coating of 20 mA, 45 seconds by JEOL auto fine coater “JFC-1300”.
6). Separation By element mapping method, the distribution of iron or barium derived from the first paint (rust preventive paint) and titanium oxide derived from the second paint (fluorinated paint) is confirmed and evaluated according to the following criteria: did.
○: The element distributions are neatly separated without mixing.
X: Element distribution was mixed.
The evaluation results of Examples 8 to 11 are shown in Table 1.

  As shown in Table 1, in Examples 8 to 11 in which the curing temperature of the first coating layer and the second coating layer was within 30 ° C., no crack was generated in the cured coating film. Moreover, curtain flow property was more favorable in the specific gravity of the 2nd coating material (fluorine-containing coating material) being 1.2 or more. Further, when the yield value of the second paint (fluorine-containing paint) is 0.5 or more, the second paint (fluorine-containing paint) is less likely to wrap around the reflection surface, and the edges are appropriately covered. Therefore, it can be expected that the penetration of moisture from the edge is suppressed and the life of the mirror is extended. Further, in Examples 9 to 11 in which the curing system of the first paint (rust preventive paint) and the curing system of the second paint (fluorinated paint) are the same, the curability is higher than that of Example 8 in which the curing system is different. It was even better.

DESCRIPTION OF SYMBOLS 10 Mirror 12 Glass substrate 14 Reflective layer 16A 1st coating layer 16 1st cured coating film 18A 2nd coating layer 18 2nd cured coating film

Claims (6)

The manufacturing method of the coated article which implements the following 1st application process, 2nd application process, and hardening process sequentially, and forms a cured coating film in the one surface side of a glass substrate.
First coating step: a step of forming a first coating layer by coating a first coating on one surface side of the glass substrate.
Second coating step: a step of coating the first coating layer on the first coating layer to form a second coating layer having a curing temperature difference of 30 ° C. or less with respect to the first coating layer.
Curing step: a step of heating the first coating layer and the second coating layer and simultaneously curing the first coating layer and the second coating layer to form a cured coating film.   The method for producing a coated article according to claim 1, wherein the first paint and the second paint are applied by a curtain flow coating method.   The first paint is at least one selected from the group consisting of at least one amine catalyst selected from the group consisting of aromatic amines, aliphatic amines, amide polyamines, and polyamides, carboxylates, sulfonates, and phosphates. Containing at least one Bronsted acid catalyst or at least one Lewis acid catalyst selected from the group consisting of tin octylate, tributyltin dilaurate, and dibutyltin dilaurate, wherein the second paint is an aromatic amine, aliphatic amine At least one amine catalyst selected from the group consisting of amide polyamines and polyamides, at least one Bronsted acid catalyst selected from the group consisting of carboxylates, sulfonates and phosphates, or tin octylate, At least selected from the group consisting of tributyltin dilaurate and dibutyltin dilaurate Method for manufacturing a coated article according to claim 1 or 2 containing one Lewis acid catalyst.   The method for producing a coated article according to any one of claims 1 to 3, wherein the glass substrate has a thickness of 0.5 to 10 mm.   The manufacturing method of the mirror which forms a cured coating film by the manufacturing method as described in any one of Claims 1-4 on the surface of the said reflection layer of the glass substrate which has a reflection layer in one surface.   The method for manufacturing a mirror according to claim 5, wherein the reflective layer is a reflective layer made of at least one selected from the group consisting of metals and metal oxides.

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