JP3207755B2 - Painted metal plate with yuzu skin appearance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated metal plate having a slick skin appearance. INDUSTRIAL APPLICABILITY The coated metal sheet of the present invention is suitable for home appliances and interior building materials, and can also be used as an outer panel for equipment.

[0002]

2. Description of the Related Art Generally, a metal plate is used after being painted. The purpose of this coating is to protect the base metal plate and at the same time to increase its durability and beautify it.
Painted metal sheets are used for large objects such as buildings, ships, bridges, etc., as well as for various machines, automobiles, furniture, small electrical appliances and household goods. As it is called, it is performed after processing and assembly. In this case, since the shape of the object to be coated is three-dimensional, non-contact type coating such as spray coating of a solvent-based coating or electrostatic coating of a powder coating has been applied. In these coating methods, the coating surface tends to have a unique yuzu skin appearance due to insufficient leveling of the coating.

[0003] In recent years, however, particularly in the field of building materials and home electric appliances, there has been a shift to a method of processing and assembling a so-called pre-coated metal plate that has been painted in advance. In this method, a roll coat, a curtain flow coat, and a roller curtain coat with higher productivity can be used, so that a paint appearance having much better surface smoothness than the post-coat method can be obtained. High smoothness leads to high definition, which is one of the reasons for the expansion of the precoat method.

[0004]

However, depending on the application site of the precoat, there is a case where harmony with the appearance of the surrounding post-coated metal plate is required. In addition, since the transport flaws, processing flaws, and the like are less noticeable in the Yuzu skin appearance than in the smooth appearance, some users prefer a Yuzu skin appearance similar to that of the post coat. Therefore, an object of the present invention is to provide a coated metal plate having a slick skin appearance in a precoating method having high productivity.

[0005]

According to the present invention, there is provided a coated metal plate having a yuzu skin appearance according to the present invention, which comprises a resin and a curing agent as an undercoat resin layer on at least one surface of the metal plate subjected to a chemical conversion treatment. A coating layer containing a coating composition containing non-heat-fusible beads is applied and baked, and a polyester resin, a curing agent, and a temperature at which a crosslinking reaction of the polyester resin and the curing agent proceeds as an overcoating resin layer on the coating layer. A coating layer that is baked in a molten or liquid state and is coated with a coating composition containing hot-melt polyester beads having a solubility parameter different from the resin and the curing agent by 1.5 or more. And In addition, in the present invention, a good yuzu skin appearance is defined as having unevenness with a pitch of 1 mm or more and gloss of 60 degrees or more at the same time.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, examples of the metal plate used for the coated metal plate of the present invention include a steel plate, an aluminum plate, a stainless steel plate, a titanium plate, and a copper plate. Examples of steel sheets include cold-rolled steel sheets, hot-rolled steel sheets, galvanized steel sheets, galvannealed steel sheets, zinc-iron alloy coated steel sheets, zinc-aluminum alloy coated steel sheets, aluminized steel sheets, chromium-coated steel sheets, and nickel-plated steel sheets. , A zinc-nickel alloy-plated steel sheet, a tin-plated steel sheet, and the like.

An undercoat resin layer is provided on at least one surface of the metal plate. The undercoat resin layer is formed of a coating composition containing a resin, a curing agent, and predetermined non-fusible beads. Although not essential, it may contain pigments, surface-modified metal powder or glass powder, additives such as dispersants and leveling agents, and diluent solvents. As the resin, polyester, acrylic, polyurethane, epoxy,
Each modified, and mutually mixed,
The resin is not particularly limited as long as it is a resin usually used for a solvent-based paint.

As a curing agent used for forming a thermosetting resin film layer by reaction with the above-mentioned resin, amino resins such as melamine resin, urea resin, benzoguanamine resin and the like, or isocyanate compounds and block bodies thereof are preferable. It is. The weight ratio of the curing agent and the resin in the dried coating film is based on 100 parts by weight of the total amount of the resin and the curing agent.
The curing agent is preferably 5 to 30 parts by weight. This means that if the curing agent is less than 5 parts by weight, the adhesion and corrosion resistance are not sufficiently exhibited,
If the amount is more than 30 parts by weight, workability and chemical resistance are reduced.

[0009] Further, non-heat-fusible beads are an essential component for generating yuzu skin. The particle size of the non-heat-fusible beads is not particularly limited, but the average particle size is about 20 μm,
Those having a maximum particle size of 50 μm or less are preferred. Also 25
At 0 ° C. or lower, it is essential that the coating is not melted. As the material, organic resins such as polyester, acrylic, polyurethane, polystyrene, vinyl chloride, fluorine, and silcon, and inorganic materials such as glass, quartz, and ceramics are preferable. The content of the beads is not particularly limited, but it is preferable that the content of the beads is 3 to 20 parts by weight in the dried coating film.

Although the thickness of the undercoat resin layer is not particularly limited,
A coating metal plate having a thickness of 2 μm or more and less than 10 μm is generally used. After the application, it is baked at 150 ° C. or more and less than 300 ° C., and is cured and dried. If the baking temperature is lower than 150 ° C., the adhesiveness is insufficient, and if it is higher than 300 ° C., the resin component is thermally degraded and the workability is deteriorated. A chemical conversion treatment layer is provided below the undercoat resin layer as needed. As the chemical conversion treatment layer, there are a chromate treatment, a zinc phosphate treatment, a composite oxide film treatment and the like, and these may be used alone or in combination. These conditions may be appropriately selected.

Next, an overcoat resin layer made of a polyester resin is provided on the undercoat resin layer. The overcoat resin layer is formed of a coating composition containing a resin, a curing agent, and predetermined hot-melt polyester beads. In addition, although not essential, additives such as a pigment, a surface-modified metal powder or a glass powder, a dispersant, a leveling agent, a wax, an aggregate, a fluororesin bead, and a diluting solvent may be contained. As the polyester resin, any polyester resin usually used as a solvent-based paint may be used, but a high-molecular polyester resin in which the main resin is constituted by ester bonds of two or more resin monomers is preferable.

As a curing agent used for forming a thermosetting resin coating layer by reaction with the above-mentioned resin, amino resins such as melamine resin, urea resin and benzoguanamine resin, or isocyanate compounds and block bodies thereof are preferable. It is. The weight ratio of the curing agent and the resin in the dried coating film is based on 100 parts by weight of the total amount of the resin and the curing agent.
The curing agent is preferably 10 to 35 parts by weight. This is because when the curing agent is 10 parts by weight or less, adhesion, corrosion resistance, and solvent resistance are not sufficiently exhibited, and when the curing agent is 35 parts by weight or more, workability, chemical resistance,
This is because the impact resistance is reduced.

[0013] Further, the heat-meltable polyester beads are an essential component for generating yuzu skin. The molecular weight and particle size of the polyester beads are not particularly limited, but those having an average molecular weight of 1,000 to 5,000, an average particle size of about 40 μm, and a maximum particle size of about 70 μm are preferable. It is thermoplastic and has a melting point of 6
The temperature is preferably 0 to 180 ° C, particularly preferably 60 to 120 ° C. Further, since poor compatibility with the resin in the molten state is essential for giving a yuzu skin appearance, the value of each solubility parameter (hereinafter abbreviated as SP) of the resin and the polyester beads is reduced. You need to be away.

Here, the SP value is a thermodynamic parameter representing an intermolecular force, a dissolving power and a solvent effect. The enthalpy of molar evaporation of a liquid is ΔH _A ^V , its molar volume is V _A , and its thermodynamic constant is R , When the absolute temperature is T, (ΔH _A ^V −R
T) ^1/2 V _A ^-1/2 (see: Gakkai Shuppan Center, edited by Hitoshi Otaki, Motoharu Tanaka, Shigenobu Funahashi, “Solution Reaction Chemistry”, p. 117). In particular, when the absolute value of the difference between the SP values is 1.5 or more, good yuzu skin appearance can be obtained. The content of the polyester beads is not particularly limited,
It is preferable that the dry coating film contains 5 to 20 parts by weight in weight ratio.

It is desirable that the polyester beads used in the overcoat resin layer have a Tg of 30 ° C. or higher or a crystalline polyester resin. This is because when the Tg of the resin is 30 ° C. or less, the coating film surface becomes sticky at room temperature. The thickness of the overcoat resin layer is not particularly limited, but is generally 10 μm or more and less than 20 μm as a coated metal plate. After applying, 150 ℃
It is baked at less than 300 ° C. and cured and dried. If the baking temperature is less than 150 ° C., the formation of the yuzu skin appearance is insufficient. If the baking temperature is 300 ° C. or more, the polyester resin component is thermally degraded and the workability is deteriorated.

As a method for applying the undercoat resin layer or the overcoat resin layer, and a method for curing and drying, a coating and baking method using a general solvent-based paint can be used. As an example, as a coating method, a roll coater, a roller curtain coater, a curtain flow coater, an electrostatic coating machine, a brush, a blade coater, a die coater, or the like can be used. As a curing and drying method, a hot air oven, an induction heating oven, a near-infrared oven, a far-infrared oven, an energy ray curing oven, standing at room temperature, and the like can be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the coated metal plate of the present invention will be described. A hot-dip galvanized steel sheet subjected to chromate treatment after alkali degreasing was used as a substrate. First, as a base coat, a coating (FLC641 primer manufactured by Nippon Paint Co., Ltd.) composed of 10 parts of a urethane resin curing agent with respect to 100 parts of a modified epoxy resin was used.
m of organically modified silicone rubber beads (Shin-Etsu Silicone Co., Ltd.) was applied in various amounts as shown in Table 1. The coating was performed using a bar coater to obtain a dry film equivalent of 5μ.
m, and then by high-frequency induction heating,
Baking was performed at a maximum ultimate plate temperature (PMT) of 215 ° C. next,
As a top coat, a white color of a paint (FLC3510H manufactured by Nippon Paint Co., Ltd.) composed of 30 parts of a melamine resin curing agent with respect to 100 parts of a polymerized polyester resin is used. HRS-100: Tg = 45
° C: with crystallinity / HRS-150: Tg = 27 ° C: without crystallinity / HHS-300: Tg = 38 ° C: without crystallinity)
Was applied in a varying amount as shown in Table 1, applied to a dry film equivalent of 13 μm, and baked at 230 ° C. PMT by a high-frequency induction heating method.

[0018]

[Table 1]

The appearance of yuzu skin of the coated plate obtained as described above was visually evaluated. The evaluation of the Yuzu skin appearance was ◎: there is a Yuzu skin appearance, Δ: poor unevenness, ×: smooth skin, and ◎ was passed. At the same time, the pitch of the unevenness was measured by two-point measurement (average of 10 measurements), and the gloss value was measured based on the 60-degree reflection method. When the pitch of the unevenness was 1 mm or more and the gloss value was 60 or more, it was determined that the surface had good Yuzu skin appearance. As is clear from Table 1, when the configuration according to the present invention is used, a coated metal plate provided with a yuzu skin appearance by the precoating method can be obtained.

[0020]

According to the coated metal sheet of the present invention, the undercoat resin layer is composed of a coating layer formed by applying and baking a coating composition containing non-fusible beads, and the upper coating resin layer is formed of a polyester resin and a curing agent. Means that the solubility parameter is 1.5
Since the coating layer is formed by applying and baking a coating composition containing the different heat-meltable polyester beads, the coating composition has a good yuzu skin appearance. By applying this to the field of home electric appliances and the like, it is possible to impart design and improve scratch resistance.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-275787 (JP, A) JP-A-6-206047 (JP, A) JP-A-7-275788 (JP, A) JP-A 54-1979 102341 (JP, A) JP-A-50-23495 (JP, A) JP-A-52-109537 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/00-15 / 20 B05D 7/14-7/18

Claims (3)

(57) [Claims] An undercoating resin layer is provided on at least one side of a metal plate subjected to a chemical conversion treatment with a coating layer formed by applying and baking a coating composition containing a resin, a curing agent, and non-heat-fusible beads. As an overcoating resin layer, a polyester resin, a curing agent, and a molten or liquid state at a temperature at which a crosslinking reaction between the polyester resin and the curing agent proceeds, and the resin and the curing agent have a solubility parameter. A coated metal plate having a yuzu skin appearance, provided with a coating layer obtained by applying and baking a coating composition containing at least 1.5 different heat-meltable polyester beads. 2. The coated metal sheet according to claim 1, wherein the heat-meltable polyester beads contained in the overcoating resin layer are made of a polyester resin having a glass transition temperature of 30 ° C. or more. 3. The coated metal sheet according to claim 1, wherein the heat-meltable polyester beads contained in the overcoat resin layer are made of a crystalline polyester resin.