JP2023104258A - Coating composition for precoated metal plate, precoated metal plate and method for producing the same - Google Patents

Abstract

To provide a coating composition for a precoated metal plate capable of forming a low-gloss (matte) coating layer having excellent processability and durability.SOLUTION: A coating composition for a precoated metal plate disclosed herein includes a polyvinylidene fluoride resin (A), an acrylic resin (B), and matting agent particles (C), with a distance (Ra) in Hansen solubility parameter (HSP) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) being 3.5 or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present disclosure relates to a coating composition for precoated metal sheets, a precoated metal sheet having a coating film formed from the coating composition, and a method for producing the same.

Painted metal sheets, which are coated metal substrates such as cold-rolled steel sheets and plated steel sheets, are also called pre-coated metal sheets (also called "PCM"), and are used in construction materials such as shutters, shutters, doors, roofs and siding, and outside coolers. It is used as various members such as exterior materials and interior materials for electrical equipment such as machines. Usually, a precoated metal plate is processed into various products after coating the surface of the metal plate to form a coating film. Therefore, the coating film formed on the precoated metal sheet is required to have flexibility and high workability such as not cracking or peeling off when the precoated metal sheet is bent.

As part of these studies, Patent Document 1 discloses that a matte base coat layer formed on a synthetic resin molded product body is formed of a base coat resin and 12 to 90 parts by mass based on 100 parts by mass of the base coat resin. It is proposed to form a base coat paint containing acrylic crosslinked particles and 0.1 to 12.0 parts by mass of amide needle-like filler.

Patent Document 2 contains polyvinylidene fluoride resin, acrylic resin, polytetrafluoroethylene particles, wax, aggregate, and a solvent, the acrylic resin contains a thermosetting acrylic resin, and the solvent is A coating composition for a precoated metal plate containing a solvent having a ketone structure and having a boiling point of 180°C has been proposed.

Patent Document 3 proposes a coating film formed by applying a polyester resin-based coating material containing a light stabilizer and a matting agent.

Patent Document 4 contains 1 to 40% by mass of ceramic inorganic aggregate, 1 to 30% by mass of polyacrylonitrile beads, and 0.5 to 10% by mass of fluororesin powder, and the inorganic aggregate particle size and film thickness is 0.04 to 1.0, and the ratio of the particle size of the polyacrylonitrile beads to the coating thickness is 1.0 to 3.0.

JP 2012-30431 A Japanese Patent Application Laid-Open No. 2020-100740 Japanese Patent Application Laid-Open No. 2007-283718 JP-A-11-156999

In recent years, even in the field of pre-coated metal sheets for building materials and processing of wares, etc., there is a demand for coated metal sheets with superior cosmetic properties. Matte-painted metal plates, etc., which are coated with topcoats that are blended with amine compounds and that form a uniform matt appearance by utilizing the difference in curing speed between the surface and the inside of the coating film, are on the market. ing.

In addition, recently, due to consumer preference for high-end products, there is a demand for a calm, low-gloss (matte) coating appearance. There is a similar demand for the system coating composition, and various coating compositions and coating methods have been investigated.

For the adjustment of glossiness, for example, as described in Patent Documents 1 to 4, various coating compositions containing matting agents such as inorganic fine particles such as silica and organic resin fine particles have been studied. ing. However, in order to obtain the required low-gloss (matte) coating film, it was necessary to incorporate a large amount of the matting agent into the coating composition. Furthermore, since the coating film obtained from the fluororesin-based coating composition has the property of easily forming a crystal structure, there is a problem that cracks are likely to occur during processing and molding. Cracks are also a factor that deteriorates the appearance of the coating film.

Therefore, there has been a long-awaited development of a fluororesin-based coating composition that is resistant to cracking, that is, has good processability and provides a low-gloss (matte) coating film.

An object of the present disclosure is to provide a coating composition for a precoated metal plate that has good workability and durability and is capable of forming a low-gloss (matte) coating film. Another object of the present disclosure relates to a precoated metal sheet using such a precoated metal sheet coating composition and a method for producing the same.

The present disclosure includes the following aspects.
[1] polyvinylidene fluoride resin (A);
an acrylic resin (B);
and matting agent particles (C),
A coating composition for a precoated metal plate, wherein the value of the distance (Ra) of the Hansen Solubility Parameter (HSP) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.5 or less. .
[2] In [1], wherein the distance (Ra) of the Hansen Solubility Parameter (HSP) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.0 or less. A coating composition for precoated metal sheets as described above.
[3] The precoated metal according to [1] or [2], wherein the difference between the refractive index of the polyvinylidene fluoride resin (A) and the refractive index of the matting agent particles (C) is 0.10 or more. Board paint composition.
[4] Any one of [1] to [3], wherein the matting agent particles (C) contain at least one selected from the group consisting of acrylic resin particles, polyester resin particles, urea resin particles and polyurethane resin particles. or a coating composition for a precoated metal plate according to any one of the above.
[5] The precoated metal according to any one of [1] to [4], wherein the matting agent particles (C) contain at least one selected from the group consisting of urea resin particles and polyurethane resin particles. Board paint composition.
[6] The content of the matting agent particles (C) is 1 part by mass or more with respect to a total of 100 parts by mass of the solid content of the polyvinylidene fluoride resin (A) and the solid content of the acrylic resin (B). The coating composition for precoated metal sheets according to any one of [1] to [5], which is 6 parts by mass or less.
[7] The content of the polyvinylidene fluoride resin (A) is 50 parts by mass or more and 80 parts by mass in a total of 100 parts by mass of the solid content of the polyvinylidene fluoride resin (A) and the solid content of the acrylic resin (B). The coating composition for a precoated metal plate according to any one of [1] to [6], which is 1 part or less.
[8] The coating composition for a precoated metal plate according to any one of [1] to [7], wherein the acrylic resin (B) contains a thermosetting acrylic resin.
[9] The coating composition for a precoated metal plate according to any one of [1] to [8], wherein the matting agent particles (C) have an average particle size of 1 μm or more and 10 μm or less.
[10] A metal plate, and a coating film disposed on at least one surface of the metal plate and formed from the precoated metal plate coating composition according to any one of [1] to [9]. , pre-coated metal sheets.
[11] The precoated metal sheet according to [10], wherein the coating film has a 60-degree specular gloss of 3 or more and 30 or less.
[12] further comprising a primer coating film disposed between the metal plate and the coating film;
The thickness of the undercoat film is 3 μm or more and 10 μm or less,
The precoated metal sheet according to [10] or [11], wherein the coating film has a thickness of 10 μm or more and 25 μm or less.
[13] The precoated metal sheet according to [12], wherein the undercoat film contains a polyester resin.
[14] The precoated metal plate coating composition according to any one of [1] to [9] is applied on at least one surface of the metal plate so that the thickness after curing is 10 μm or more and 25 μm or less. to obtain a coating film, and the coating film is coated under the conditions that the temperature reached by the metal plate is 230 ° C. or more and 270 ° C. or less, and the drying and curing time is 20 seconds or more and 120 seconds or less, A method for producing a precoated metal sheet, comprising drying and curing to obtain a coating film.

The coating composition for precoated metal sheets of the present disclosure has good workability and durability, and can form a low-gloss (matte) coating film. Another object of the present disclosure is to provide a precoated metal sheet using such a precoated metal sheet coating composition and a method for producing the same.

The coating composition for a precoated metal plate of the present disclosure (hereinafter also simply referred to as "coating composition") contains a polyvinylidene fluoride resin (A), an acrylic resin (B), and matting agent particles (C). , the value of the distance (Ra) of the Hansen Solubility Parameter (HSP) representing the compatibility between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.5 or less. According to the coating composition for precoated metal sheets of the present disclosure, it is possible to form a coating film with good workability and durability and low glossiness (matte property). Although not bound by any particular theory, in a composition containing a polyvinylidene fluoride resin, an acrylic resin, and matting agent particles, it is the matting agent particles and the polyfluoride that contribute to the suppression of cracking and peeling of the resulting coating film. It was found by the study of the present inventors that it is the affinity of the interface of the vinylidene resin. Furthermore, focusing on the Hansen solubility parameter (HSP) as an index of the compatibility between the polyvinylidene fluoride resin and the matting agent particles, the distance (Ra) of the Hansen solubility parameter between the polyvinylidene fluoride resin and the matting agent particles is predetermined. The present inventors have found that cracking of the obtained coating film is effectively suppressed while the effect of low gloss due to the matting agent particles is exhibited by setting the value to a value or less, and the present invention has been completed.

The coating composition of the present disclosure contains a polyvinylidene fluoride resin (A) and an acrylic resin (B) as coating film-forming resins.

[(A) Polyvinylidene fluoride resin]
The polyvinylidene fluoride resin (A) may be a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride, which is the main component, and other monomers. By containing the polyvinylidene fluoride resin (A), weather resistance and durability can be imparted to the resulting coating film.

Polyvinylidene fluoride resin (A) is obtained by polymerizing a mixture of monomers containing vinylidene fluoride. Such polymerization may be carried out, for example, using a radical polymerization initiator or the like under high temperature and high pressure. The other monomer is not particularly limited as long as it has an ethylenic carbon-carbon double bond. The other monomer may be a monomer having a fluorine atom, and examples of the monomer having a fluorine atom include hexafluoropropylene and tetrafluoroethylene. When other monomers contain fluorine atoms, the weather resistance of the copolymer can be further improved.

The polyvinylidene fluoride resin (A) may have functional groups such as carboxyl groups and sulfonic acid groups.

Polyvinylidene fluoride resin (A) contains a homopolymer of vinylidene fluoride. When the polyvinylidene fluoride resin (A) contains a homopolymer of vinylidene fluoride, good weather resistance and stability of the coating composition (for example, storage stability) can be balanced. The content of the vinylidene fluoride homopolymer in the polyvinylidene fluoride resin (A) may be, for example, 90% by mass or more and 100% by mass or less, preferably 95% by mass or more and 100% by mass or less.

The weight average molecular weight of the polyvinylidene fluoride resin (A) is 100,000 or more and 700,000 or less, for example, 150,000 or more and 500,000 or less, or 150,000 or more and 400,000 or less.
In addition, in this indication, a weight average molecular weight is the value which converted the measured value by the gel permeation chromatography (GPC) method into the polystyrene standard.

The melting point of the polyvinylidene fluoride resin (A) is 140° C. or higher and 190° C. or lower, preferably 150° C. or higher and 180° C. or lower.

A commercially available product may be used as the polyvinylidene fluoride resin (A). For example, HYLAR 5000 (manufactured by Solvay), Kynar 500 (manufactured by Arkema) and the like can be exemplified.

In one aspect, the content of the solid content of the polyvinylidene fluoride resin (A) is, for example, 50 parts by mass or more and 80 parts by mass in a total of 100 parts by mass of the solid content of the polyvinylidene fluoride resin (A) and the acrylic resin (B). parts or less, preferably more than 55 parts by mass and 80 parts by mass or less.
The coating composition of the present disclosure can sufficiently ensure weather resistance and durability by containing the polyvinylidene fluoride resin (A) within the above range.
Hereinafter, in the description of the content, the term "resin content" means "resin solid content". For example, "polyvinylidene fluoride resin content" means "solid content of polyvinylidene fluoride resin (A)", and "acrylic resin (B) content" means "acrylic resin (B) means the solids content of The same applies to thermosetting acrylic resins and thermoplastic acrylic resins.

[(B) acrylic resin]
Since the coating composition of the present disclosure contains the acrylic resin (B) as the coating film-forming resin, it has the effect of improving adhesion to the undercoat film, film-forming properties, and pigment dispersibility.

Furthermore, the acrylic resin (B) contains at least one thermosetting acrylic resin. In the present disclosure, a thermosetting acrylic resin means a resin containing a copolymer of acrylic monomers capable of undergoing a polymerization/curing reaction by applying heat (for example, 140° C. or higher). In one aspect, the thermosetting acrylic resin can be cured by a polymerization/curing reaction by applying heat at a temperature of 160° C. or higher, for example, 200° C. or higher. By including a thermosetting acrylic resin in the acrylic resin (B), weather resistance, water resistance, chemical resistance, etc. can be imparted while maintaining excellent workability. In addition, deterioration of workability due to aging and deterioration of workability due to heat generated during processing can be suppressed.

For example, when the acrylic resin (B) according to the present disclosure contains a thermosetting acrylic resin, the content of the thermosetting acrylic resin is a total of 100 parts by mass of the polyvinylidene fluoride resin (A) and the acrylic resin (B). , for example, 20 to 46 parts by mass, preferably 25 to 39.9 parts by mass, more preferably 28 to 39.9 parts by mass.

In some embodiments, the acrylic resin (B) may contain two or more thermosetting acrylic resins. In one aspect, in the aspect in which the acrylic resin (B) contains two or more acrylic resins, at least one may be a thermosetting acrylic resin and the others may be thermoplastic acrylic resins. In the present disclosure, thermoplastic acrylic resin means acrylic resin other than thermosetting acrylic resin. Thermoplastic acrylic resins typically soften when they reach their glass transition temperature or melting point.

When the acrylic resin (B) contains a thermosetting acrylic resin and a thermoplastic acrylic resin, the content of the thermoplastic acrylic resin is the sum of the solid content of the thermosetting acrylic resin and the solid content of the thermoplastic acrylic resin. For 100 parts by mass, it may be, for example, 20 to 99 parts by mass, preferably 30 to 99 parts by mass. When the ratio of the thermosetting acrylic resin and the thermoplastic acrylic resin is within the above range, the obtained coating film can be provided with weather resistance, water resistance, chemical resistance, etc., and the workability of the obtained coating film can be further improved. have the effect of improving

In one embodiment, when the acrylic resin (B) contains two or more acrylic resins, it may contain at least one thermosetting acrylic resin and at least one thermoplastic acrylic resin. By including a thermosetting acrylic resin and a thermoplastic acrylic resin, it is possible to impart weather resistance, water resistance, chemical resistance, etc. to the obtained coating film, and the effect of further improving the workability of the obtained coating film. be. Furthermore, the adhesion between the coating composition and the undercoat film can be improved. As a result, even in embodiments where the precoated metal sheet has a known undercoat film, the coating composition of the present disclosure can have good adhesion.

The coating composition of the present disclosure may contain a cross-linking agent, depending on the structure of the film-forming resin. Further, the thermosetting acrylic resin includes a resin that gels by itself at a temperature equal to or higher than the above temperature.

In one embodiment, the thermosetting acrylic resin may be a self-crosslinking acrylic resin obtained by copolymerizing monomer components such as N-hydroxyacrylamide, N-alkoxyacrylamide, N-alkylolacrylamide, and diacetoneacrylamide. , a curing agent combined type acrylic resin that is crosslinked by using together an acrylic monomer having a substituent such as a hydroxyl group and a crosslinking agent such as melamine.

For example, the acrylic resin (B) can be prepared by copolymerizing a hydroxyl group-containing monomer (b-1) and another monomer (b-2) in addition to the above monomers.

Examples of the hydroxyl group-containing monomer (b-1) include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, and 4-hydroxy(meth)acrylate. Examples include butyl, reaction products of these hydroxyl group-containing (meth)acrylic esters and ε-caprolactone, and esters of polyhydric alcohols such as polyethylene glycol mono(meth)acrylate and (meth)acrylic acid. Furthermore, a reactant obtained by ring-opening polymerization of ε-caprolactone to a monoesterified product of polyhydric alcohol and (meth)acrylic acid can also be used. These hydroxyl group-containing monomers (b-1) may be used alone or in combination of two or more.
In the present disclosure, (meth)acrylic acid means acrylic acid or methacrylic acid.

Examples of other monomers (b-2) include carboxyl group-containing monomers such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid, and ethyl maleate, butyl maleate, ethyl itaconate, and itaconic acid. Dicarboxylic acid monoester monomers such as butyl acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n, i or t-butyl (meth) acrylate, (meth) acrylic acid 2 -(meth)acrylic acid alkyl ester monomers such as ethylhexyl and lauryl (meth)acrylate; cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate , alicyclic group-containing monomers such as adamantyl (meth)acrylate; (meth)acrylic acid aminoalkyl esters such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and butylaminoethyl (meth)acrylate Monomers; aminoalkyl (meth)acrylamide monomers such as aminoethyl (meth)acrylamide, dimethylaminomethyl (meth)acrylamide, and methylaminopropyl (meth)acrylamide; other N-substituted (meth)acrylamides such as acrylamide and methacrylamide Monomers; vinyl cyanide monomers such as (meth)acrylonitrile and α-chloroacrylonitrile; saturated aliphatic carboxylic acid vinyl ester monomers such as vinyl acetate and vinyl propionate; styrene monomers such as styrene, α-methylstyrene and vinyltoluene bifunctional monomers such as divinylbenzene and ethylene glycol (meth)acrylate; These other monomers (b-2) may be used singly or in combination of two or more.
Among the other monomers (b-2), (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, (meth) ) Cyclohexyl acrylate and the like are preferably used.

As a method for polymerizing the hydroxyl group-containing monomer (b-1) and the other monomer (b-2), methods commonly used by those skilled in the art can be used. As the polymerization method, for example, a bulk polymerization method using a radical polymerization initiator, a solution polymerization method, a bulk-suspension two-stage polymerization method in which suspension polymerization is performed after bulk polymerization, or the like can be used. Among these, the solution polymerization method can be used particularly preferably. The solution polymerization method includes, for example, a method of heating the monomer mixture in the presence of a radical polymerization initiator at a temperature of 80 to 200° C. while stirring.

The number average molecular weight of the acrylic resin (B) may be from 3,000 to 150,000, in one embodiment from 3,000 to 50,000, for example from 3,500 to 30,000; 3,500 to 20,000 in the aspect of When the number average molecular weight of the acrylic resin (B) is within the above range, both good coating film hardness and workability can be achieved, and a coating film with excellent weather resistance can be formed. Further, when the number average molecular weight of the acrylic resin (B) is within the above range, the drying property of the coating composition is improved.
In addition, in this indication, a number average molecular weight is a value by polystyrene conversion measured by GPC (gel permeation chromatography).
Moreover, when the acrylic resin (B) contains a plurality of types of acrylic resins, the number average molecular weight of the acrylic resin (B) indicates the number average molecular weight of a mixture thereof.

The hydroxyl value of the acrylic resin (B) is, for example, 0 mgKOH/g or more and 250 mgKOH/g or less, preferably 0 mgKOH/g or more and 100 mgKOH/g or less, more preferably 0 mgKOH/g or more and 70 mgKOH/g or less.
When the hydroxyl value is within the above range, good reactivity as a thermosetting acrylic resin, good dispersibility of color pigments, and good adhesion to the undercoat film can be ensured.
In addition, in this disclosure, the hydroxyl value of the resin indicates a solid content conversion value and is a value measured by a method based on JIS K 0070.
Moreover, when the acrylic resin (B) contains a plurality of kinds of acrylic resins, the hydroxyl value of the acrylic resin (B) as a whole is preferably included in the above range. In another aspect, the weighted average value of the hydroxyl value of each acrylic resin contained in the acrylic resin (B) may be included in the range.

The glass transition temperature (Tg _B ) of the acrylic resin (B) is, for example, 10° C. or higher and 120° C. or lower, preferably 20° C. or higher and 80° C. or lower. When the glass transition temperature of the acrylic resin (B) is within such a range, excellent workability can be imparted while ensuring the hardness, scratch resistance, water resistance, chemical resistance, and corrosion resistance of the coating film. Moreover, the coating film can be satisfactorily dried.
In the present disclosure, the glass transition temperature is a value measured with a differential thermal scanning calorimeter, and can be measured with, for example, a differential scanning calorimeter DSC-6100 (manufactured by Seiko Instruments Inc.).

A commercially available acrylic resin may be used as the acrylic resin (B). Specific examples of such acrylic resins include the Acrydic series (manufactured by DIC), the Dianal series (manufactured by Mitsubishi Chemical), the Hitaroid series (manufactured by Hitachi Chemical Co., Ltd.), the PARALOID series (manufactured by Dow Chemical), and the like. is mentioned. These may be used alone or in combination of two or more.

The total content of the polyvinylidene fluoride resin (A) and the acrylic resin (B) in the coating film-forming resin is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less. .

[Other coating film-forming resins]
In the coating composition of the present disclosure, in addition to the polyvinylidene fluoride resin (A) and the acrylic resin (B) as the coating film-forming resin, other resins within a range that does not affect the performance of the coating composition and the resulting coating film may contain Such other resins include urethane resins, polyester resins, polyether resins, polystyrene resins, melamine resins, polyamide resins, polyimide resins, and the like.

[(C) Matting agent particles]
The coating composition of the present disclosure contains matting agent particles (C). By containing the matting agent particles (C), the coating composition can form a matte coating film with excellent workability.

The matting agent particles (C) preferably have a Hansen Solubility Parameter (HSP) distance (Ra) value between the polyvinylidene fluoride resin (A) and the matting agent particles (C) of 3.5 or less. is a particle with a value of 3.0 or less. When the Ra value is in such a range, there is an advantage that the workability of the resulting coating film is improved.

Further, the difference in refractive index between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is preferably 0.1 or more. When the refractive index difference is within such a range, there is an advantage that a coating film having good gloss adjustment effect and workability can be obtained.

The matting agent particles (C) are not particularly limited as long as they satisfy the Hansen Solubility Parameter (HSP) distance (Ra) value and refractive index difference, but include resin particles. Such resin particles include, for example, at least one selected from the group consisting of polyurethane resin particles, urea resin particles, polyester resin particles, vinyl butyral resin particles, styrene resin particles and acrylic resin particles, preferably polyurethane resin particles. At least one selected from the group consisting of particles, urea resin particles, polyester resin particles and acrylic resin particles, more preferably at least one selected from the group consisting of polyurethane resin particles and urea resin particles. By including such particles in the matting agent particles (C), there is an advantage that a coating film having a good gloss-adjusting effect and workability can be obtained.

The average particle size of the matting agent particles (C) is 1 μm or more and 10 μm or less and 2 μm or more and 8 μm or less. When the average particle size is within the above range, it is said that the storage stability and coating workability of the resulting coating composition are compatible, and that the physical properties such as the appearance and workability of the resulting coating film are improved. There are advantages.
In the present disclosure, the average particle diameter of the particles is the median diameter (D50) of the volume-based particle size distribution measured by the laser diffraction scattering method using a Microtrac particle size distribution analyzer (trade name “MT3300”, manufactured by Nikkiso Co., Ltd.). is the value of

The solid content of the matting agent particles (C) is, for example, 0.1 parts by mass or more and 10.0 parts by mass with respect to a total of 100 parts by mass of the polyvinylidene fluoride resin (A) and the acrylic resin (B). Hereinafter, it is preferably 0.5 parts by mass or more and 8 parts by mass or less. When the content of the matting agent particles (C) is within the above range, there is an advantage that a coating film with low gloss and good workability can be obtained.

(Urea resin particles)
Urea resin particles comprise a urea resin, which can be a reaction product of urea and an aldehyde. The urea resin particles may be powdery and can be produced by pulverizing urea resin. The average particle size of the urea resin particles is, for example, 1-10 μm, preferably 2-8 μm.

Formaldehyde, acetaldehyde, crotonaldehyde, benzaldehyde and the like can be used as the aldehyde component. Among these, when formaldehyde is used, the condensation reaction proceeds easily, which is convenient. Commercially available urea resin particles include Pergopack M3, Pergopack M4, Pergopack M5 (manufactured by Lonza Japan Co., Ltd.), SOOFINE JJ POWDER (manufactured by Hangzhou Seisai Kako Co., Ltd.), and the like.

(urethane resin particles)
The urethane resin particles contain a urethane resin, and such a urethane resin may be a reaction product of a polyol, a polyisocyanate, and an optional chain extender and/or terminal terminator.

Examples of the polyols include polymer polyols such as polyether polyols, polyester polyols, polycarbonate polyols, glycerol polycaprolactone triols; and low molecular weight polyols. The number average molecular weight of such polymer polyols may be, for example, from 300 to 5,000, or even from 500 to 3,000. Further, the number of hydroxyl groups contained in the polymer polyol may be 2-3.

Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Examples of the polyester polyol include polybutylene adipate, polyhexamethylene adipate, polyneopentyl adipate, and the like. includes polycaprolactone diol, poly-3-methylvalerolactone diol, polyhexamethylene carbonate and the like.

Examples of the low molecular weight polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, cyclohexanediol, hexanediol, dicyclohexanediol, Aliphatic polyols such as dicyclohexanedimethanol, hydrogenated bisphenol A and cyclohexanetriol; bisphenol compounds such as bisphenol A, bisphenol F and bisphenol AD; and aromatic polyols such as ethylene oxide adducts or propylene oxide adducts of such bisphenol compounds. triols such as trimethylolpropane and trimethylolethane; and polyols having carboxyl groups such as dimethylolacetic acid, dimethylolpropionic acid and dimethylolbutyric acid.

Examples of the chain extender include the low-molecular-weight polyols; Examples include polyamine compounds such as ethylenetetramine and tetraethylenepentamine.

Examples of the terminal terminator include methanol, ethanol, propanol, butanol, ammonia, dibutylamine, aminosilane and the like.

(polyester resin particles)
The polyester resin particles contain a polyester resin, and the polyester resin includes a reaction product of a polyol and a polycarboxylic acid. Examples of the polyol include the compounds exemplified as the low-molecular-weight polyol. Examples of the polycarboxylic acids include (anhydrous) succinic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, (anhydrous) hexahydrophthalic acid, (anhydrous) trimellitic acid, (anhydrous) pyro Merritt acid and the like can be mentioned. The acid value of the polyester resin particles may be 100 mgKOH/g or less.

(Polyvinyl butyral resin particles)
The vinyl butyral resin particles contain a polyvinyl butyral resin, and the polyvinyl butyral resin includes a reaction product of polyvinyl alcohol and butyraldehyde. The reaction of polyvinyl alcohol and butyraldehyde may be carried out under acidic conditions.

(Styrene resin particles and/or acrylic resin particles)
The styrene resin particles and/or acrylic resin particles include styrene resin and/or acrylic resin, and the styrene resin and/or acrylic resin may be polymers of ethylenically unsaturated monomers. Examples of ethylenically unsaturated monomers include the monomers exemplified as the hydroxyl group-containing monomer (b-1); and the monomers exemplified as the other monomer (b-2).

As the ethylenically unsaturated monomer, a monomer having two or more ethylenically unsaturated bonds in one molecule may be used. The monomer having two or more ethylenically unsaturated bonds in one molecule is not particularly limited, and examples thereof include ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth) ) acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane diol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, glycerol di(meth)acrylate, glycerol aryloxydi ( meth)acrylate, 1,1,1-trishydroxymethylethane di(meth)acrylate, 1,1,1-trishydroxymethylethane tri(meth)acrylate, 1,1-trishydroxymethylpropane di(meth)acrylate, Unsaturated monocarboxylic acid esters of polyhydric alcohols such as 1,1,1-trishydroxymethylpropane tri(meth)acrylate; triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate, etc. and aromatic monomers substituted with two or more vinyl groups such as divinylbenzene.

In the present disclosure, resin particles obtained using a styrene-based monomer are referred to as styrene resin particles, and resin particles obtained without using a styrene-based monomer are referred to as acrylic resin particles.

The total content of the resin particles in the matting agent particles (C) is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less.

In the present disclosure, the distance (Ra) of the Hansen Solubility Parameter (HSP) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.5 or less, preferably 0 or more and 3.0 or less, and may be 0.5 or more and 3.0 or less. When the Hansen solubility parameter between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is within the above range, the workability of the obtained coating film is improved.
In the present disclosure, the unit of Hansen Solubility Parameter (HSP) and distance (Ra) is (MPa) ^0.5 .

The Hansen Solubility Parameter (HSP) is an index representing how much affinity (compatibility) a certain substance (X) has with another substance (Y). Specifically, the Hansen Solubility Parameter (HSP) is the solubility parameter introduced by Hildebrand that Hansen splits into three components: the dispersion term δd, the polar term δp, and the hydrogen bonding term δh. It is digitized using a vector in dimensional space. The dispersion term δd indicates the effect of the dispersion force, the polar term δp indicates the effect of the dipole force, and the hydrogen bonding term δh indicates the effect of the hydrogen bonding force. The closer the distance (HSP distance (Ra)) between the coordinates of a substance (X) vector and the coordinates of another substance (Y) vector in a three-dimensional space, the easier it is to dissolve each other (higher compatibility). .
HSP distance (Ra) is defined by the following formula.
Ra=[4(δd _X −δd _Y ) ² +(δp _X −δp _Y ) ² +(δh _X −δh _Y ) ² ] ^1/2
δd _i : Dispersive force term of substance i δp _i : Polarity term of substance i δh _i : Hydrogen bond term of substance i

For the definition and method of calculation of the Hansen Solubility Parameter, see Charles M. et al. Hansen, "Hansen Solubility Parameters: A Users Handbook" (CRC Press, 2007).

In the present disclosure, the Hansen Solubility Parameters of polyvinylidene fluoride resin (A) and matting agent particles (C) can be calculated using computer software (Hansen Solubility Parameters in Practice (HSPiP) version 5.3.05).
Specifically, 20 mL of various organic solvents listed in Table 1 are added to 0.2 g of polyvinylidene fluoride resin (A) or matting agent particles (C). After standing still for 30 minutes, those that dispersed or dissolved were judged as good solvents, and those that precipitated or were insoluble were judged as poor solvents. Based on the affinity evaluation results, Hansen lysing spheres were prepared using the HSPiP (version 5.3.05), and Hansen solubility parameters were calculated.

In the present disclosure, the difference between the refractive index of the polyvinylidene fluoride resin (A) and the refractive index of the matting agent particles (C) is preferably 0.1 or more, more preferably 0.1 or more and 0.3 or less. you can Within the above range, a high matting effect can be obtained with the addition of a small amount of (C), and the workability of the obtained coating film will be good.

The refractive index of the polyvinylidene fluoride resin (A) and the matting agent particles (C) is determined according to B method (immersion method using a microscope (Becke line method)) in JIS K 7142 "Plastic refractive index measurement method". It was measured.
That is, polyvinylidene fluoride resin or matting agent particles are placed on a slide glass, and a refractive liquid (manufactured by CARGILLE: a plurality of Cargill standard refractive liquids prepared in units of refractive index difference of 0.01) is dropped. Then, after mixing the matting agent particles and the refraction liquid, the polyvinylidene fluoride resin or the matting material is observed with an optical microscope from above while irradiating light from a high-pressure sodium lamp NX35 (manufactured by Iwasaki Electric Co., Ltd., center wavelength: 589 nm) from below. The contour of the agent particles was observed. Then, when the contour is not visible, it is determined that the refractive index of the refractive liquid and the polyvinylidene fluoride resin or the matting agent particles are equal, and the refractive index of the refractive liquid is the refractive index of the polyvinylidene fluoride resin or the matting agent particles. bottom. The measurement temperature was 25°C.

The matting agent particles (C) may contain inorganic particles such as silica particles as long as the workability of the resulting coating film is not impaired.

(other ingredients)
In the coating composition of the present disclosure, the solid content may be, for example, 20% by mass or more and 80% by mass or less, further 25% by mass or more and 75% by mass or less, and particularly 30% by mass or more and 70% by mass or less. In the present disclosure, the solid content means the total of components other than the solvent in the coating composition.

[solvent]
The coating composition of the present disclosure may contain a solvent. Examples of solvents include water; ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, Glycol-based organic solvents such as dipropylene glycol monoethyl ether and propylene glycol monomethyl ether acetate; Alcohol-based organic solvents such as methanol, ethanol, isopropyl alcohol, isobutanol and benzyl alcohol; Ether-based organic solvents such as dioxane and tetrahydrofuran; Methoxybutyl acetate, ethyl acetate, isopropyl acetate, ester organic solvents such as butyl acetate; ketone organic solvents such as methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, isophorone; N-methyl-2-pyrrolidone, toluene, pentane, iso -Pentane, hexane, iso-hexane, cyclohexane, solvent naphtha, mineral spirits, T-SOL 100, T-SOL 150 (both aromatic hydrocarbon solvents, manufactured by ENEOS) and the like. Among these, ketone organic solvents such as cyclohexanone and isophorone. These solvents may be used alone or in combination of two or more.

[Other ingredients]
In addition to the components (A) to (C), the coating composition of the present disclosure may optionally contain coloring pigments, extender pigments, other additives, etc. depending on the purpose and application. However, other additives and the like can be added in a manner that does not impair the physical properties of the coating composition of the present disclosure.

Other additives include curing catalysts such as p-toluenesulfonic acid, tin octoate, dibutyltin dilaurate, lead 2-ethylhexoate, calcium carbonate, kaolin, clay, titanium oxide, talc, barium sulfate, Pigments such as mica, red iron oxide, manganese blue, carbon black, aluminum powder, pearl mica, wax, defoamer, leveling agent, thickener, plasticizer, antioxidant, UV absorber, anti-cratering agent, Anti-skinning agents and the like are included.

The 60-degree specular glossiness of the coating film formed from the coating composition of the present disclosure is, for example, 3 or more and 30 or less, and may be 5 or more and 20 or less.
In the present disclosure, the 60-degree specular gloss can be measured according to JIS K 5600-4-7.

(Method for preparing coating composition)
The method of preparing the coating composition according to the present disclosure is not particularly limited. For example, it can be prepared by selecting and using a mixer such as a sand grind mill, ball mill, blender, paint shaker or disper, disperser, kneader, etc., and mixing each component.

(object to be coated)
Objects to be coated with the coating composition for precoated metal plates of the present disclosure include, for example, galvanized steel sheets, zinc-aluminum alloy-plated steel sheets, aluminum alloy-plated steel sheets, hot-dip A zinc-aluminum-magnesium alloy plated steel sheet, a stainless steel sheet, a cold-rolled steel sheet, and the like can be mentioned. In addition to these steel sheets or plated steel sheets, metal sheets such as aluminum sheets (including aluminum alloy sheets) can also be applied.

The metal plate according to the present disclosure is preferably surface-treated. Specifically, the metal plate of the present disclosure is preferably subjected to pretreatment such as alkaline degreasing treatment, hot water washing treatment, and water washing treatment, and then subjected to chemical conversion treatment. The chemical conversion treatment may be carried out by a known method, examples of which include chromate treatment, non-chromate treatment such as zinc phosphate treatment, and the like.

In one aspect, the precoated metal plate has a metal plate and a coating film disposed on at least one surface of the metal plate and formed from the precoated metal plate coating composition according to the present disclosure.

In one aspect, the film thickness of the coating film formed from the coating composition for precoated metal plate may be, for example, 10 μm or more and 25 μm or less, and further 15 μm or more and 23 μm or less. When the film thickness of the coating film formed from the coating composition for precoated metal sheets is within such a range, the workability of the precoated metal sheet is further improved.

The 60-degree specular glossiness of the coating film is, for example, 3 or more and 30 or less, and may be 5 or more and 20 or less.

When the precoated metal plate has a coating film formed from the precoated metal plate coating composition according to the present disclosure on one side, the other side may be a coating film formed from a known coating composition. good.

For example, the other side may have a coating formed from known coating compositions, such as coating compositions containing epoxy resins and/or polyester resins.

The precoated metal sheet may further have a primer coat disposed between the metal sheet and the coating formed from the coating composition of the present disclosure. By having the undercoat film, the adhesion and corrosion resistance of the coating film formed from the coating composition of the present disclosure can be enhanced. In addition, since the properties of the coating film formed from the coating composition of the present disclosure can be more strongly supplemented, the durability of the precoated metal sheet can be enhanced.

In one aspect, the undercoat film preferably contains a polyester resin or a urethane resin. In one embodiment, the film thickness of the undercoat film is 3 μm or more and 15 μm or less, for example, 5 μm or more and 10 μm or less.

(Coating film forming method)
When applying the coating composition of the present disclosure, it is preferable to apply chemical conversion treatment such as phosphate treatment or chromate treatment to the surface of the metal plate or the like to be coated, and then apply the coating composition thereon. By coating the coating composition of the present disclosure on the surface of the metal plate subjected to chemical conversion treatment in this way, the adhesion of the coating film to the surface of the metal plate is improved, and the corrosion resistance is also improved. It is also possible to form an undercoat film (primer film) on the surface of the metal plate that has undergone chemical conversion treatment, and then apply coating thereon.

The method of applying the coating composition to the surface of the metal plate is not particularly limited, but conventionally known methods such as roll coater, airless spray, electrostatic spray, and curtain flow coater can be employed, preferably roll coater and curtain flow. It is better to paint with a coater. After coating, the coating film is baked by heating means such as hot air heating, infrared heating, or induction heating to crosslink the resin to obtain a cured coating film.

In the method for producing a precoated metal sheet of the present disclosure, the precoated metal sheet coating composition of the present disclosure is applied on at least one surface of the metal sheet so that the thickness after curing is 10 μm or more and 25 μm or less. and drying and curing the coating film under the conditions that the temperature reached by the metal plate is 230° C. or more and 270° C. or less, and the drying and curing time is 20 seconds or more and 120 seconds or less. to obtain a coating film.

Here, "on the surface" does not refer to an absolute direction such as vertical information defined by the direction of gravity, but refers to an outward direction between the outer side and the inner side of the substrate bounded by the main surface. Thus, "on the major surface" is a relative direction determined by the inorganic nature of the major surface. In addition, "above" an element includes not only the position directly above (on) in contact with the element, but also the position above the element, i.e., the position above the element via another object. It also includes the upper position (above) with the .

In one embodiment, after the coating composition is applied, the coating film can be dried and cured (baked) under the condition that the highest material reaching temperature is 230°C or higher and 260°C or lower.

After the baking treatment, the precoated metal sheet can be obtained by cooling to room temperature. Cooling after the baking treatment is preferably carried out by quenching the plate temperature to room temperature with water.

The film thickness of the cured coating film of the precoated metal sheet thus formed is, for example, 10 μm or more and 25 μm or less, and in one aspect, the film thickness is 12 μm or more and 23 μm or less.
A precoated metal plate provided with a coating film having even better processability, aesthetic appearance and weather resistance by having the film thickness of the coating film formed from the coating composition for precoated metal plate within such a range. can be obtained.

The coating composition for a precoated metal plate of the present disclosure is particularly preferably used as a topcoat of a 2-coat/2-bake system or a 3-coat/3-bake system. When used in the 3-coat/3-bake system, it is used in normal 3-coat/3-bake between the coating film and the primer coating film (undercoat coating film) of the precoated metal plate coating composition of the present disclosure. Apply an intermediate coating film.

The present disclosure will be described more specifically with the following examples, but the present disclosure is not limited thereto.

Each component used for preparation of the coating composition is as follows. Moreover, the manufacturing method is demonstrated about an acrylic resin (B).

(1) Materials used Polyvinylidene fluoride resin (A)
(A-1) Kynar 500 (manufactured by Arkema); Hansen solubility parameters: δd = 17.7, δp = 13.0, δh = 9.3, refractive index: 1.42; Solid content concentration: 100% by mass

(Production Example B-1)
Synthesis of acrylic resin (B-1) (thermosetting acrylic resin) 667.5 parts by mass of isophorone was charged into a reaction vessel equipped with a reflux condenser, dropping funnel, stirrer, thermometer, condenser, and nitrogen gas inlet. , and the temperature was raised to 90° C. under a nitrogen atmosphere. To this, 7.65 parts by weight of methacrylic acid, 310.8 parts by weight of methyl methacrylate, 168.9 parts by weight of n-butyl acrylate, 1.0 parts by weight of ethylene glycol dimethacrylate and 11.6 parts by weight of N-methoxymethylacrylamide A mixed solution of parts by mass and a mixed solution of 1.5 parts by mass of 2,2'-azobisisobutyronitrile and 47.5 parts by mass of isophorone as initiators were simultaneously dropped through a dropping funnel at a constant rate for 3 hours. bottom. After the dropwise addition was completed, stirring was continued for 30 minutes while maintaining the temperature at 90°C, and then the reaction vessel was heated to 120°C. Next, a mixed solution of 5 parts by mass of 2,2'-azobisisobutyronitrile and 35 parts by mass of isophorone was added dropwise at a constant speed over 30 minutes. After the completion of dropping, the mixture was stirred for 2 hours while maintaining the temperature at 120° C., acrylic resin (B-1) (solid content concentration: 40% by mass, solid content acid value: 10 mgKOH/g, solid content hydroxyl value: 0 mgKOH/g, glass transition temperature: 30°C, number average molecular weight: 120,000).

(Manufacturing Example B-2)
Synthesis of acrylic resin (B-2) (thermoplastic acrylic resin) 667.5 parts by mass of isophorone was charged into a reaction vessel equipped with a reflux condenser, a dropping funnel, a stirrer, a thermometer, a condenser and a nitrogen gas inlet, The temperature was raised to 90° C. under a nitrogen atmosphere. To this, 7.65 parts by weight of methacrylic acid, 310.8 parts by weight of methyl methacrylate, 168.9 parts by weight of n-butyl acrylate, 1.0 parts by weight of ethylene glycol dimethacrylate and 11. parts by weight of 2-hydroxyethyl methacrylate. A mixed solution of 6 parts by mass and a mixed solution of 1.5 parts by mass of 2,2'-azobisisobutyronitrile and 47.5 parts by mass of isophorone as initiators were simultaneously passed through a dropping funnel for 3 hours at a constant rate. Dripped. After the dropwise addition was completed, stirring was continued for 30 minutes while maintaining the temperature at 90°C, and then the reaction vessel was heated to 120°C. Next, a mixed solution of 5 parts by mass of 2,2'-azobisisobutyronitrile and 35 parts by mass of isophorone was added dropwise at a constant speed over 30 minutes. After the dropwise addition, the mixture was stirred for 2 hours while maintaining the temperature at 120°C, and the acrylic resin (B-2) having a solid content acid value of 10 mgKOH/g, a solid content hydroxyl value of 0 mgKOH/g, and a Tg of 30°C (solid content concentration: 40% by mass, solid content acid value: 10 mgKOH/g, solid content hydroxyl value: 0 mgKOH/g, glass transition temperature: 30°C, number average molecular weight: 10,000).

Matting agent particles (C)
(C-1) Urea resin particles 1: Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.) average particle size: 3 μm, Hansen solubility parameter: δd = 18.5, δp = 12.8, δh = 11.5, refractive index: 1 .66, solid content concentration: 100% by mass
(C-2) Urea resin particles 2: Eposter M05 (manufactured by Nippon Shokubai Co., Ltd.) average particle size 5 μm, Hansen solubility parameters: δd=18.5, δp=12.8, δh=11.5, refractive index: 1. 66, solid content concentration: 100% by mass
(C-3) Urethane resin particles 1: Grandpearl GU-0700P (manufactured by Aica Kogyo Co., Ltd.) average particle size: 7 μm, Hansen solubility parameters: δd = 17.9, δp = 13.3, δh = 10.7, refraction Ratio: 1.66, Solid content concentration: 100% by mass
(C-4) Urethane resin particles 2: Artpearl U-600T (manufactured by Aica Kogyo Co., Ltd.) average particle size: 7 μm, Hansen solubility parameter: δd = 17.9, δp = 13.3, δh = 10.7, refraction Ratio: 1.66, Solid content concentration: 100% by mass
(C-5) Urethane resin particles 3: Grandpearl GU-2000P (manufactured by Aica Kogyo Co., Ltd.) average particle size: 20 μm, Hansen solubility parameter: δd = 17.9, δp = 13.3, δh = 10.7, refraction Ratio: 1.66, Solid content concentration: 100% by mass
(C-6) Polyester resin particles: Grandpearl GU-2000P (manufactured by Aica Kogyo Co., Ltd.) average particle size: 20 μm, Hansen solubility parameter: δd = 17.7, δp = 10.6, δh = 11.6, refractive index : 1.66, solid content concentration: 100% by mass
(C-7) Styrene resin particles: MA2003 (manufactured by Nippon Shokubai Co., Ltd.) average particle size: 3 μm, Hansen solubility parameter: δd = 18.9, δp = 10.9, δh = 10.7, refractive index: 1.56 , Solid content concentration: 100% by mass
(c-1) Acrylic resin particles: Ganzpearl GM-0801 (manufactured by Aica Kogyo Co., Ltd.) average particle size: 8 μm, Hansen solubility parameter: δd = 19.7, δp = 11.2, δh = 8.7, refractive index : 1.49, solid content concentration: 100% by mass
(c-2) Silica particles; Cysilia 435 (manufactured by Fuji Silia Co., Ltd.) average particle size: 6 μm, Hansen solubility parameter: δd = 18.6, δp = 12.2, δh = 18.2, refractive index: 1.54 , Solid content concentration: 100% by mass

(2) Preparation method of paint and coating film (test plate) (Example 1)
Preparation of coating composition 1
Kynar 500 (solid content concentration: 100% by mass) 19 parts by mass, acrylic resin (B-1, solid content concentration: 40% by mass) 16 parts by mass, acrylic resin (B-2, solid content concentration: 40% by mass) 16 parts by mass 28 parts by mass of isophorone, 3 parts by mass of cyclohexanone, 11 parts by mass of xylene, and 11 parts by mass of pigment, and mixed using a sand mill (dispersion medium: glass beads) until the maximum particle size of the pigment coarse particles is 10 μm or less. Dispersion composition 1 was prepared. To the resulting dispersion composition 1, 4 parts by mass of High Disper 1250 and 0.3 parts by mass of matting agent particles (C-1) were added and uniformly mixed with a disper to prepare coating composition 1.

Preparation of test plate On the back side of the coated plate (zinc-aluminum alloy plated steel plate; 300 mm × 200 m × 0.35 mm) with chromate treatment (coating amount 150 mg / m2) on both front and back sides, Super Rack R-90 (Nippon Paint・Industrial Coatings Co., Ltd., epoxy resin paint) is applied with a bar coater so that the dry film thickness is 5 μm, then baked at a maximum material temperature of 210 ° C for 60 seconds, then immediately submerged in water and cooled. A backcoat was formed.

On the other hand, fine tough G primer (manufactured by Nippon Paint Industrial Coatings Co., Ltd., epoxy resin primer: paint composition 40) was applied as an undercoat to the surface with a bar coater so that the dry film thickness was 5 μm. , Baking was performed for 60 seconds under the condition that the maximum temperature reached by the material was 210°C to form an undercoat film. Next, after coating the coating composition 1 prepared in Production Example 1 with a bar coater so that the dry film thickness is 15 μm, the material is baked at a maximum temperature of 250 ° C. for 60 seconds, and immediately submerged in water and cooled. , to form a topcoat film.

(Examples 2 to 14, Comparative Examples 1 to 3)
Coating compositions 2 to 16 were prepared in the same manner as in Example 1, except that the polyvinylidene fluoride resin (A), the acrylic resin (B), and the matting agent particles (C) were changed as shown in Table 1. A topcoat film was formed in the same manner as in Example 1 except that the coating compositions 2 to 17 were used instead of the coating composition 1.

(3) Evaluation item 1) Paint film appearance (glossiness)
The 60° glossiness of the coating films obtained in Examples and Comparative Examples was measured using a gloss meter VG 7000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 5600-4-7 (specular glossiness). bottom.

2) Workability (initial and aging)

A test plate obtained in each example and comparative example was cut into a width of 50 mm, and a workability test was carried out in a room at 23°C.
Specifically, several coated plates having the same thickness (0.35 mm) as the test piece to be processed were sandwiched inside the test piece to be processed (with the coating surface facing outward), and were folded 180 degrees. . The processed part was observed with a magnifying glass of 10 times and evaluated.
A case in which three coated plates were sandwiched was defined as "3T", and the minimum value at which cracks were not observed in the processed portion was taken as the workability evaluation result. For example, the evaluation "4T" indicates the case where no cracks were found in the machined part at 4T, but cracks were found at the machined part at 3T.
The test was conducted immediately after the production of the coated plate (initial) and after the plate was left at room temperature for one month (time). 4T or less was accepted at the initial stage, and 6T or less was accepted after the passage of time.

Examples 1 to 14 are examples of the present invention, the glossiness was adjusted to a low gloss range, and the initial workability and aging workability were good.
Comparative Example 1 is an example in which the distance (Ra) of the Hansen Solubility Parameter between the polyvinylidene fluoride resin and the matting agent particles exceeds 3.5. was not satisfactory. Moreover, since the difference in refractive index between the polyvinylidene fluoride resin and the matting agent particles is less than 0.1, it is necessary to use a large amount of the matting agent particles.
Comparative Example 2 is an example in which the distance (Ra) of the Hansen Solubility Parameter between the polyvinylidene fluoride resin and the matting agent particles exceeds 3.5. However, the workability deteriorated with the passage of time, and the durability was not sufficiently satisfactory.
Comparative Example 3 is an example containing no acrylic resin, and a coating composition could not be produced.

Claims (14)

polyvinylidene fluoride resin (A);
an acrylic resin (B);
and matting agent particles (C),
A coating composition for a precoated metal plate, wherein the value of the distance (Ra) of the Hansen Solubility Parameter (HSP) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.5 or less. . 2. The precoat according to claim 1, wherein the value of the Hansen Solubility Parameter (HSP) distance (Ra) between the polyvinylidene fluoride resin (A) and the matting agent particles (C) is 3.0 or less. Coating composition for metal plates. 3. The coating composition for a precoated metal plate according to claim 1, wherein the difference between the refractive index of said polyvinylidene fluoride resin (A) and the refractive index of said matting agent particles (C) is 0.10 or more. . 4. The matting agent particles (C) according to any one of claims 1 to 3, comprising at least one selected from the group consisting of acrylic resin particles, polyester resin particles, urea resin particles and polyurethane resin particles. A coating composition for precoated metal plates. The coating composition for a precoated metal plate according to any one of claims 1 to 4, wherein the matting agent particles (C) contain at least one selected from the group consisting of urea resin particles and polyurethane resin particles. . The content of the matting agent particles (C) is 1 part by mass or more and 6 parts by mass with respect to a total of 100 parts by mass of the solid content of the polyvinylidene fluoride resin (A) and the solid content of the acrylic resin (B). The coating composition for precoated metal plates according to any one of claims 1 to 5, which is the following. The content of the polyvinylidene fluoride resin (A) is 50 parts by mass or more and 80 parts by mass or less in a total of 100 parts by mass of the solid content of the polyvinylidene fluoride resin (A) and the solid content of the acrylic resin (B). The coating composition for precoated metal plates according to any one of claims 1 to 6. The coating composition for a precoated metal plate according to any one of claims 1 to 7, wherein the acrylic resin (B) contains a thermosetting acrylic resin. The coating composition for a precoated metal plate according to any one of claims 1 to 8, wherein the matting agent particles (C) have an average particle size of 1 µm or more and 10 µm or less. A precoated metal plate comprising a metal plate and a coating film disposed on at least one surface of the metal plate and formed from the coating composition for precoated metal plate according to any one of claims 1 to 9. The precoated metal sheet according to claim 10, wherein the coating film has a 60-degree specular gloss of 3 or more and 30 or less. Further comprising a primer coating film disposed between the metal plate and the coating film,
The thickness of the undercoat film is 3 μm or more and 10 μm or less,
The precoated metal sheet according to claim 10 or 11, wherein the coating film has a thickness of 10 µm or more and 25 µm or less. 13. The precoated metal sheet according to claim 12, wherein the undercoat film contains a polyester resin. On at least one surface of the metal plate, the precoated metal plate coating composition according to any one of claims 1 to 9 is applied so that the thickness after curing is 10 μm or more and 25 μm or less, Obtaining a coating film, and drying and curing the coating film under conditions in which the metal plate reaches a temperature of 230° C. or more and 270° C. or less, and the drying and curing time is 20 seconds or more and 120 seconds or less. , a method for producing a precoated metal sheet, comprising obtaining a coating film.