JPH09207265A - Coated metal sheet having orange peel appearance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated metal sheet to which an orange peel appearance is added in a precoated steel sheet system by a coil. SOLUTION: In this metal sheet, a chemical conversion treated layer, a primer layer, and a polyester resin coated layer containing a heat fusible polyester bead are provided on at least one side of the metal sheet. An orange peel appearance is obtained by specifying a melting point of the polyester bead, and a difference in soluble parameter between the polyester resin and the polyester bead.

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. In particular, the coated metal sheet of the present invention is suitable for home electric appliances and interior building materials, and is also applicable as an outer panel for articles, and relates to a coated metal sheet having a smooth skin appearance.

[0002]

2. Description of the Related Art Conventionally, a metal plate is generally coated and used. 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 plates are used for large objects such as buildings, ships, bridges, etc., as well as for various machines, automobiles, furniture, small 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.

However, in recent years, particularly in the field of building materials and home appliances, pre-painted so-called pre-coated metal sheets have been processed.
We are moving to a method of assembling. 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, it is an object of the present invention to provide a coated metal plate having a rough skin appearance in a precoating method having high productivity.

[0005]

The coated metal sheet of the present invention which achieves the above-mentioned object is a polyester resin coating layer containing a chemical conversion treatment layer, a primer layer and heat-meltable polyester beads in order on at least one surface of the metal sheet. It is characterized by having.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. 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, aluminum-coated 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. First, a chemical conversion treatment layer is provided on at least one surface of the metal plate. 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, a primer layer for an undercoat film is provided on the chemical conversion treatment layer. A primer layer can be formed by applying a primer undercoat on a metal plate and curing and drying. There are polyester-based, epoxy-based, urethane-based, etc. as undercoat paints for primers, which are roll coaters, curtain flow coaters,
Roller curtain coater, electrostatic coating machine, brush, blade coater, die coater, etc. to achieve the required film thickness, then leave at room temperature or hot air oven, induction heating furnace, near infrared furnace, far infrared furnace, energy Harden and dry in a wire curing oven. Although the film thickness is arbitrary, in the case of a coated metal plate, a dry film thickness of about 1 to 30 μm, particularly about 3 to 12 μm is generally used.

Next, a top-coating polyester resin coating layer is provided on the primer layer in order to maintain processability and appearance. As the polyester resin, any conventionally used polyester resin paint may be used,
Desirably, a high molecular polyester coating is used, in which the main resin is composed of ester bonds of two or more kinds of resin monomers, and a melamine alkyd resin, a urethane alkyd resin or the like is used as a curing agent component.

In the present invention, the polyester resin is mixed with polyester beads to give a soft skin appearance. For polyester beads, the molecular weight
The particle size is not limited, but the average molecular weight is 1000 to 50.
00, the average particle size is about 40 μm, and the maximum particle size is about 70 μm. It is also thermoplastic and has a melting point of 60 to 180 ° C., especially 60 to 180 ° C.
It is preferably 120 ° C. Further, since it is essential that the compatibility with the coating resin in the molten state is poor, the solubility parameter values (hereinafter abbreviated as SP) of the coating resin and the polyester beads are required to be different from each other.

[0010] Here, the SP value, intermolecular force and solvency are thermodynamic parameters representing a solvent effect, [Delta] H the molar vaporization enthalpy of the liquid _A ^V, the molar volume V _A, the thermodynamic constants R , Where T is the absolute temperature, (ΔH _A ^V −R
T) can be represented by ^1/2 V _A ^-1/2 . (Reference: Hitoshi Otaki, Motoharu Tanaka, Shigenobu Funahashi, "Chemistry of Solution Reactions", p. 117, edited by Academic Publishing Center). 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 beads is not particularly limited, but it is preferable that the content of the beads is 5 to 20% by weight in the coating film. Also,
In order to prevent sticking after forming the appearance of a yuzu skin, the glass transition temperature (hereinafter abbreviated as Tg) of the beads is preferably 35 ° C. or higher. For the same purpose, it is possible to impart crystallinity to the beads.

In the polyester resin coating layer, it is possible to mix a color pigment, an extender pigment, a rust preventive pigment, or other additives. Furthermore, surface-modified glass pieces or metal pieces may be mixed in order to add design characteristics such as metallic or pearl. The film thickness of the polyester resin coating layer is not particularly limited, but if the film thickness is 10 μm or more and less than 20 μm, a good skin appearance can be obtained.

The method for mixing the beads is not particularly limited, and the beads can be mixed according to a commonly used method. After coating, it is baked at 150 ° C. or higher but lower than 300 ° C., cured and dried. The baking temperature is the highest plate temperature (hereinafter abbreviated as PMT). If the temperature is lower than 150 ° C, the appearance of a wrinkled skin due to the difference in melting and compatibility of beads is insufficient, and if it is 300 ° C or higher, the heat of the polyester resin component is high. It is not suitable as a product due to deterioration and deterioration of workability. As the method of applying the resin coating material and the method of curing and drying, the method described in the method of forming the primer layer can be used.
It should be noted that a coating layer may be formed between the primer layer and the resin coating layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the coated metal plate of the present invention will be described. After alkaline degreasing, PEUC manufactured by Nippon Paint Co., Ltd. at 4 μm and PMT of 215 ° C. was applied and baked on the chromate-treated hot-dip galvanized steel sheet as an undercoat. Next, as shown in Table 1, SP values and melting points were different, and the average molecular weight was 35.
No. 00, average particle size 40 μm, and maximum particle size 70 μm were mixed, and topcoat paints with different mixing amounts were applied. FLC3510 (SP value = 10.5) manufactured by Nippon Paint Co., Ltd. was used as the original polyester paint. After coating, PMT230 ℃ by high frequency induction heating method
Baked in. With respect to the obtained coated metal plate, the appearance of the rough skin was visually evaluated. The evaluation was made as ◎: distressed skin, ◯: slightly distressed skin, ×: smooth skin. As is clear from the results shown in Table 1, when the bead-mixed resin coating material according to the present invention was used and the melting point of the beads and the SP value difference (ΔSP) between the coating resin and the beads were within the appropriate ranges, the polyester resin coating material was discolored. A skin appearance can be imparted.

[0014]

[Table 1]

[0015]

As described above, a coated metal plate having a smooth skin appearance is produced by a precoating method by mixing beads having a specified melting point and SP value with the top coating polyester resin coating layer of the coated metal plate. be able to. By applying this to the field of home electric appliances and the like, it is possible to impart design and improve scratch resistance.

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Claims (3)

[Claims] 1. A coated metal plate having a yuzu-skin appearance, which comprises a chemical conversion treatment layer, a primer layer, and a polyester resin coating layer containing heat-meltable polyester beads in that order on at least one side of the metal plate. 2. The melting point of the heat-meltable polyester beads is 6.
The coated metal sheet according to claim 1, wherein the coated metal sheet has a rough skin appearance, which is 0 to 180 ° C. 3. A coated metal having a smooth skin appearance according to claim 1 or 2, wherein the absolute value of the difference in solubility parameter between the heat-meltable polyester beads and the polyester resin is 1.5 or more. Board.