JPS6211577A - Production of double-precoated thin sheet - Google Patents

Abstract

PURPOSE:To produce the titled high-quality double-precoated thin sheet to be used in household electrical products by repeating plural times a process of spraying a solvent-type paint on both faces of a thin sheet and a process of curing the coated film by using a far infrared radiation heater. CONSTITUTION:A thin sheet 3 is horizontally arranged, a solvent-type paint is sprayed thereon by a spray coating machine 1 and the coated film is cured by a far infrared radiation heater 2. The process is applied plural times to both faces of the thin sheet 3. Consequently, a double-precoated thin sheet having smooth and beautiful faces can be obtained and curing is also carried out in an extremely short time. Accordingly, the precoated thin sheet can be produced with a saved space and energy can also be saved.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is achieved by repeating the process of spraying a solvent-based paint on both sides of a sheet-like thin plate and curing the paint film using a far-infrared radiator multiple times. The present invention relates to a method for producing high-quality double-sided precoated thin sheets for use in home appliances, which could not be obtained by conventional coating using a no-roll coater or curtain flow coater and using a circulating hot air furnace.

BACKGROUND OF THE INVENTION Conventional Technology In the painting of home appliances, pre-coated thin sheets have been introduced from the viewpoints of energy saving, space saving, pollution control, cost reduction, etc., in place of conventional post-coating.

Conventional methods for producing pre-coated thin plates include coating with a roll coater or flow coater, and baking and curing the coating film using a hot air circulating oven. [“
"Current status of paints for home appliances" (Rust Prevention Management 11 ('821))
``Regarding the Coating of Home Appliances in the Future'' (Practical Surface Technology 10 ('801), etc.) Problems to be Solved by the Invention However, when manufacturing pre-coated thin sheets using the conventional method, it is difficult to use a roll coater to produce coiled thin sheets. For example, it is possible to produce a pre-coated thin plate with a beautiful surface using a reverse roll coater, but when it comes to sheet-like thin plates (so-called cut plates), only a natural roll coater can be used, and there are no roll marks on the coating surface. remains, resulting in poor appearance quality.Furthermore, if you try to paint both sides, the paint will bleed onto the back side, and if both sides are painted in different colors, the appearance will be unsightly.

On the other hand, in the case of a curtain flow coater, a pre-coated thin plate with a beautiful appearance can be obtained even when the plate is cut, but if the plate is warped, the paint is likely to shake and cause defects such as wrinkles. The edges are particularly prone to wrinkles, so it is necessary to cut off the four corners after painting with a cutting board.

In either method, if you try to manufacture a double-sided pre-coated sheet, there is a problem that the back side is easily scratched by the conveyor, and in addition, the surface coated first becomes overbaked under hot air atmosphere conditions, reducing workability. At the same time, there was a problem in that the color also changed. For this reason, although there are double-sided precoated thin plates in the industry, the back side is usually provided as a service coat without guaranteeing scratches, color, or processing quality.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method in which a thin sheet-like plate is arranged horizontally, a solvent-based paint is sprayed thereon, and then the paint film is cured by a far-infrared radiant heating element. The present invention provides a method for producing a double-sided precoated thin plate by repeating the step of forming a double-sided precoated thin plate multiple times on both sides of the sheet-like thin plate.

Effect The present inventor has discovered an effective method for producing a double-sided precoated thin plate for application to home appliances such as multi-layered microwave oven containers. This method has extremely important practical significance as an industrial method for producing precoated thin sheets.

The thin sheets targeted here include untreated bare steel sheets,
Steel plates such as galvanized steel sheets, zinc phosphate treated steel sheets, and thin aluminum sheets can be used.

As pre-coat paints, epoxy paints, polyester paints, acrylic paints, vinyl paints, etc. have been conventionally used, and any of them can be applied. By spraying paint dissolved in a solvent onto horizontally arranged thin sheets, a painted surface with an extremely beautiful appearance can be obtained. Because the coating is cured by heating using a far-infrared radiant heating element rather than a hot air drying oven, a temperature difference occurs between the front side and the back side of the coating film due to the directionality of the light. This temperature difference is important when painting the back side after one side has already been painted. In particular, when compared to a hot air circulation furnace, in a hot air circulation furnace, the previously painted surface is overbaked and the paint film is softened and easily scratched, but a far-infrared radiant heating element is used. Therefore, since a temperature difference is generated between the front and back surfaces, overbaking can be avoided, which is also advantageous in the problem of scratches.

Example Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a conceptual diagram of the present invention. In Figure 1, 1 is a spray paint machine that sprays solvent-based paint downward. 2 is a far-infrared radiant heating body. This far-infrared radiant heating body is
The sheet-like thin plate 3 onto which the paint was sprayed from above is heated. Both air and airless spray paint machines are applicable. When moving the sheet-like thin plate horizontally, a plurality of spray paint machines may be installed, or the spray paint machine itself may be moved in the form of a rem locator. After a setting time of 1 to 5 minutes with the wet coating film formed, the coating film is completely cured using a far-infrared radiant heating element.

As the far-infrared radiation heating body, it is preferable to use a heat-resistant metal base material such as stainless steel, or a ceramic base material such as alumina coated with far-infrared paint. As the heating energy source, electricity, gas, and oil can all be used.

100 ffffX 100 ffffX 0.5ff
The test was carried out using an electrogalvanized steel sheet with dimensions l+(7). The paint is ■Nira 1 to #180 manufactured by Dainippon Toyo Co., Ltd.
Primer and #6100 top coat paint were used.

As a far infrared heating element, 200+1ffX200ff!
IX□, on a 9m stainless steel plate, a far-infrared radiant paint containing polyborosiloxane resin as a binder and a mixture of zirconium oxide, aluminum oxide, and titania was applied to a film thickness of about 20μm, and heated at 600'C. 30
The separately fired product was used as a heat radiating plate, a sheathed heater was attached to the back side to form a planar radiator, a thermocouple was attached to the surface to control the temperature, and this was placed on the ceiling in a 20 Crn x 20 Crn x 20 cm A furnace was constructed.

For safety, air was taken in and exhausted from the furnace at an air volume of 2 (1/min).

Attach thermocouples to the front and back of the test piece so that the surface temperature of the electrogalvanized steel sheet can be measured from both sides.
180 primer 7 μm 1 $6100 Top coat 12 μm wet-on-wet was applied, the surface temperature of the far-infrared radiator was set to 500°C, and the distance between the test piece and the far-infrared radiator was set to 12 (7). However, the temperature of the coating film surface reached 245°C in about 90 seconds. At this time, the temperature of the back surface was 183'C. The paint film is completely cured.

Next, when I performed the same process on the back side, it took about 80 seconds.
The coated side is 243°C, and the surface coated first is 1
It was 78°C.

Next, when the temperature of the far-infrared heating element was set to 700°C and a similar test was carried out, both the front and back sides were completely cured in about 35 to 40 seconds. In this case as well, the temperature difference between the heated surface and the back surface is
The temperature was approximately 60°C.

Effects of the Invention As described above, the present invention uses a far-infrared radiant heating element to spray a solvent-based paint onto a horizontally arranged sheet-like thin plate, and then heat and harden it, so that it can be pre-coated on both sides with a smooth and beautiful surface. Not only can a thin plate be obtained, but it can be cured in an extremely short time. Therefore, it is possible to manufacture FRECOAT thin plates in a space-saving manner, which also results in energy savings.

The color change is simple because it is a spray method, and it can be applied to plates of various sizes, and it is extremely effective in practice, as it is excellent in responding to multi-product production.

[Brief explanation of drawings]

The figure is a sectional view of a method for manufacturing a double-sided precoated thin plate according to an embodiment of the present invention. 1...Spray paint machine, 2...Far-infrared radiant heating element, 3...Sheet-like thin plate.

Claims (1)

[Claims] A method for producing a double-sided precoated thin plate, in which the process of arranging a sheet-like thin plate horizontally, spraying a solvent-based paint thereon, and curing the coating film with a far-infrared radiant heating element is repeated multiple times on both sides of the sheet-like steel plate.