JPH0414441A - Colored metal plates for plastic processing and containers for heating cookers - Google Patents

Abstract

PURPOSE:To easily obtain a fluororesin-coated metal product having a desired indication thereon through only deformation processing by a method wherein an opaque colored coating layer is formed on a metal plate, an indicating layer having thereon letters, diagrams, patterns and the like indicated differently from coloration is formed on the colored coating layer and a clear fluororesin coated-layer is formed on the indicating layer. CONSTITUTION:An opaque colored layer is first formed on a metal plate by coating method, symbols, letters, diagrams, patterns and the like are then indicated thereon by printing method and a clear fluororesin through which the indicating layer is visible practically is thereafter coated thereon. The coating layer of this clear fluororesin is heated and printed, preferably at a temperature of at most 450 deg.C. To form the colored coating layer, a heat resisting resin base such as fluororesin, polyimide and polyamidimide, a solvent such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone and the coating material containing coloring component are used. As the coloring component, an inorganic pigment such as white titanium oxide and black carbon black is used, preferably with a particle size of at most 1mum in diameter.

Description

Detailed Description of the Invention (a) Purpose of the Invention (Field of Industrial Application) The present invention is applicable to the manufacture of various kitchen appliances (especially inner pots for heating cookers) and various building materials (for example, roofing materials). The present invention relates to a fluororesin-coated metal plate for plastic working used, and a cooking device body formed by press-molding the metal plate.

(Prior art) Fluororesin has excellent heat resistance, chemical resistance, weather resistance, non-adhesiveness, and sliding properties, and has been used in the manufacture of various kitchen appliances, building materials, sealing materials, etc. It is used for this purpose.

To manufacture kitchen appliances using fluororesin, fluororesin is coated on a roughened flat metal plate and then baked to create a fluororesin-coated flat metal plate, which is then plastic-processed into a predetermined shape and made into a product. The method is - used in boat fishing.

Plastic processing during the production of such kitchen appliances (for example, inner pots for heating cookers) causes large deformation of the metal plate, so in order to maintain sufficient adhesion between the metal plate and the fluororesin, the metal plate must be Generally, the surface is roughened.

In addition, kitchen utensils, etc. are
For example, it is desirable to put food materials such as rice, water, etc., and to display a scale, letters, etc. as a guide. For this reason, traditionally, stamps were made using impact force using a press machine, etc.
The above-mentioned scales, letters, etc. are displayed on the fluororesin-coated metal plate to be plastically worked, as in -C.

However, in this case, there was a drawback that the scales and characters obtained by engraving were unclear, and the fluororesin coating was damaged by the die used for stamping, and the original characteristics of the fluororesin coating were There was a drawback that the properties of the fluororesin coating were impaired and the performance of the fluororesin coating film on the engraved area was significantly reduced.

In addition, in order to manufacture building materials such as roofing materials, a metal plate that has been wound into a coil is continuously unwound and subjected to degreasing and chemical conversion treatment, and then coated with fluororesin, baked, and once rolled up. A method is used for boat fishing, in which the metal plate is rewound again and cut into a predetermined shape and size, and the resulting fluororesin-coated metal plate is plastic-processed to make a roofing material or the like.

(Problems to be solved by the invention) The present invention provides a metal plate for plastic working that allows a fluororesin-coated metal product with a desired mark, character, figure, pattern, etc. to be easily obtained simply by plastic working. Another object of the present invention is to provide a cooking device body formed by press-forming the same metal plate.

Another object of the present invention is to provide a metal plate for plastic working which is colored arbitrarily in place of the background color inherent to the metal plate.

(b) Structure of the invention (means for solving problems) The metal plate for plastic working of the present invention is provided with an opaque colored coating layer (hereinafter sometimes abbreviated as a first colored layer), and the colored coating layer A mark using a coloring agent different from the coloring on the top,
This is a metal plate in which a clear fluororesin coating layer is provided on a metal plate on which characters, figures, patterns, etc. are displayed (hereinafter sometimes referred to as a display layer).

To manufacture the metal plate for plastic working of the present invention, an opaque colored layer is provided on the metal plate using a coating method, and then marks, letters, figures, patterns, etc. are displayed using a printing method, etc. Next, a clear fluororesin that allows the display layer to be seen through is applied thereon. The clear fluororesin coating layer is preferably baked at a temperature of 450°C or less.

Further, the cooking device body of the present invention is formed by press-forming the above-mentioned metal plate for plastic working of the present invention.

As the metal plate in the present invention, for example, an aluminum plate, an aluminum alloy plate, a stainless steel plate, a laminate of these metals (i.e., a gland plate), etc. can be used. The metal plate is usually preferably in the form of a flat plate (including a coiled material).

In order to manufacture the metal plate for plastic working of the present invention, the raw metal plate (including a coiled metal plate) is subjected to treatments such as degreasing, chemical conversion treatment, roughening treatment, etc. in advance as necessary. Examples of surface roughening treatment methods include chemical etching,
Etching methods such as electrolytic etching, mechanical surface roughening methods such as barrel grinding, hairline method, shot blasting, or a combination of these methods may be used. The degree of roughening is important for improving the adhesion of fluororesins, etc., and the surface is usually roughened to an average roughness (Ra) of 0.5 to 5μ, preferably 1 to 3μ. is desirable.

Next, an opaque colored coating layer is formed on the pretreated metal plate. For this purpose, fluororesin, polyimide, polyamideimide, polyether sulfone,
Heat-resistant resin base such as polyphenylene sulfide, polyarylate, polysulfide, polyarylsulfone, polysulfone, polyetherimide, polyetheretherketone, polyphenylene ether, etc., or mixtures thereof, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethyl Sulfoxide, γ
-Butyrolactone, propylene carbonate, isopho. A paint containing a solvent such as a mixture of cyclohexanone and methyl ethyl ketone, and a coloring component is used. Coloring components include inorganic pigments such as white titanium oxide, black carbon black, blue phthalocyanine blue, and brown to red iron oxide (red iron oxide), which have a particle size of 1.
Fine particles of μ or less are preferable.

Other coloring components that can be used include metal powders such as aluminum powder, magnesium powder, and copper powder, and colored mica. Since these coloring components are coarse particles with a particle size of 5 μm or more, the coloring is slightly non-uniform and a so-called metallic colored coating layer with rich gloss is obtained. For example, when aluminum powder is used, a metallic silver color can be obtained, and when yellow to golden mica is used, a metallic gold color can be obtained.

These paints can be applied onto a metal plate by an air spray method, a roll coating method, a screen printing method, or the like.

The first colored layer has a display layer on it, so it is 100 to 20.
After drying at 0°C, it is usually cured by firing at 300 to 500°C, but if the display layer is provided using a method such as an inkjet method that does not apply external shearing force to the first colored layer, the firing process is necessary. Simply 150°C
Drying at a temperature below is sufficient. In addition to the method of providing the display layer by directly coating it on the first colored layer,
There is also a method of using a clear fluororesin film surrounding the display, but this will be described later.

Next, marks, letters, figures, patterns, etc. (hereinafter sometimes simply referred to as "patterns, etc.") are displayed using coating methods, printing methods, inkjet methods, etc.; A desired pattern or the like is displayed on the board by screen printing or the like using a plate corresponding to the desired pattern or the like.

Next, marks, letters,
A clear fluororesin coating layer is provided on a metal plate on which figures, patterns, etc. are displayed. The clear fluororesin coating layer is usually provided so as to cover at least one side of the metal plate having a pattern or the like, or may be partially coated in some cases.

As a method for providing a clear fluororesin coating layer, there are usually a method of applying a fluororesin and a method of pasting a fluororesin film.

The fluororesin used for the clear fluororesin coating layer is: ■Polytetrafluoroair 1, (PTF)
E), ■Tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ■Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (P
FA), ■Ethylene-tetrafluoroethylene copolymer (ETFE), ■Polyvinyl fluoride (PVF),
(2) Room temperature reaction-curing fluoroethylene-hydrocarbon vinyl ether copolymers are used.

These fluororesins are applied to metal plates, for example, as a dispersion in a suitable liquid medium (e.g., a mixture of water and a surfactant, or a mixture of water, toluene, and a surfactant, etc.). However, if necessary, an inorganic or organic filler can be mixed into the dispersion within a range that does not impair the performance of the clear system. Examples of the filler include ferrous oxide, titanium oxide, carbon black, mica powder pre-colored, other organic pigments, and inorganic pigments.

The "clear fluororesin" described in this specification refers to the total light transmittance specified by JISK-7105 at a predetermined thickness formed by coating or pasting on a metal plate with a pattern etc. (measured with a haze meter) is 40-100
% of the fluororesin layer (including fluororesins containing fillers, etc.).

The clear fluororesin can be applied by coating the above-mentioned fluororesin in the form of a dispersion or the like using a spray method, flow coating method, roll coating method,
Apply using a method such as the Gui coat method. As for the method of forming the fluororesin into a paint, an appropriate method is used depending on the shape of the gold MIIi and the like. The coating thickness of the clear fluororesin to be applied is usually 5 to 100 μm when dried or baked.
- Preferably selected from the range of 20 to 50μ.

The clear fluororesin coating film can be cured at a low temperature around room temperature (as shown below) or heated and baked at an appropriate temperature (however, in the case of a coiled metal plate, it can be further shaped into a predetermined shape and (Cut to size.) This becomes the desired metal plate for plastic working.

The temperature conditions for curing or baking a clear fluororesin coating vary depending on the type of fluororesin, and the following temperatures are usually used.

■Polytetrafluoroethylene 350-450°C (
PTFE) ■Ethylene-tetrafluoroethylene copolymer (ETFE) 250 to 350°C ■Polyfluorinated vinyl (PvF) 200 to 300°C ■Fluoroethylene-hydrocarbon vinyl ether copolymer Room temperature to 250°C
■Fluoroethylene-hydrocarbon vinyl ether copolymer coating can react and cure even at room temperature based on carboxyl groups, hydroxyl groups, amino groups, etc. introduced into the copolymer derived from hydrocarbon vinyl ether. It is. However, if curing at room temperature takes too long, heating can accelerate the curing reaction, for example, curing can be achieved at 140°C for 30 minutes or at 180°C for 10 minutes.

The clear fluororesin coating layer can be formed by applying and curing the fluororesin as described above, or by processing the fluororesin into a film in advance and pasting it.

At this time, instead of applying a coloring agent to the metal plate in advance or forming a pattern, etc. by printing, etc., a method of heating and pasting a film molded body on which a display layer of a pattern, etc. is formed by a printing method, etc. with a coloring agent. is also suitable.

Of course, in this case, in order to prevent abrasion and deterioration of weather resistance and durability of the display layer, the film is attached with the pattern-forming side facing the metal plate.

The above-mentioned fluororesins ① to ② can all be processed into films according to conventional methods, but the resin ① cannot be processed into films, and therefore is not preferred for the above-mentioned film pasting method.

These fluororesin films can be easily attached and fixed by heat-pressing at the above-mentioned predetermined temperature.

The metal plate for plastic working of the present invention obtained as described above can be easily finished into a final product by plastic working, and the final product has a colored bottom layer and a Underneath the fluororesin coating layer, necessary markings, letters, figures, or patterns are provided, and the indications are clear and protected by the fluororesin layer even while the product is in use. Since it is coated with a rubber film, there is no possibility of peeling or the like.

Examples of the plastic working method for the metal plate for plastic working include methods such as bending, spinning, drawing, and roll forming.

(Examples, etc.) Examples will be described in detail below.

Example 1 Aluminum alloy (JIS-A3003
), one side of which was roughened to a matte finish by shot blasting and chemical etching using ferric chloride.

Next, PTFE dispersine in which golden-colored mica (average particle size of about 50 μm) was dispersed was applied to the rough side by an air spray method, and baked at 360° C. for 10 minutes. After that, a screen printing plate with scales and characters created in advance, and a fluororesin with the following composition,
A black display layer was formed using a polyimide resin colorant.

Composition of colorant: Polyimide: 30 parts by weight Polytetrafluoroethylene: 70 parts by weight N-methylpyrrolidone: 50 parts by weight Coloring component (carbon black): 0.5 parts by weight After drying this at 275°C for 10 minutes, a PTFE aqueous dispersion was prepared. (Resin concentration: 60 parts by weight) was applied by an air spray method. 1 at 380"C
Firing treatment was performed for 0 minutes to form a transparent fluorocarbon resin coating layer with a thickness of 30 μm.

The obtained PTFE-coated disk was cylindrical deep drawing pressed,
It was molded into an inner pot for a rice cooker with a bottom diameter of 200 m and a height of 150III+. This inner pot was a molded body with a metallic gold-colored inner surface on which black scales and letters were clearly displayed. In order to test the durability and corrosion resistance of the fluororesin coating layer and display, we added "Oden base" liquid (
When boiled continuously for 96 hours, no abnormalities such as stains, corrosion, or peeling were observed in the fluororesin coating or color display.

Example 2 A fluororesin dispersion paint using titanium oxide pigment (average particle size 0.5μ) was applied by air spray method onto the same rough surface of a metal plate as in Example 1, and baked at 360°C for 10 minutes. did. Thereafter, in the same manner as in Example 1, a black display layer and a transparent PTFE coating layer with a thickness of 30 μm were formed.

The obtained coated disk was molded in the same manner as in Example 1 to obtain an inner pot having an inner surface with black scales and letters on a beige-white background.

Example 3 On a disc on which a beige-white coating was formed in the same manner as in Example 2, instead of the transparent PTFE coating layer of Example 2,
Using an ETFE clear film with a thickness of 50 μm, a display layer made of the same black colorant as in Example 1 was provided on the film by screen printing, and the display layer was hot-pressed with the display layer facing the beige-white coating side. The ETFB film was laminated using the method described above, and the film was further heated at 300° C. for 10 minutes to complete the fusion. This ETFE-coated disk was molded into an inner pot in the same manner as in Example 1, and the same tests were conducted, and the same results as in Example 1 were obtained.

(C) Effects of the Invention The metal plate for plastic working of the present invention has a colored fluororesin coating layer just by plastic working, and can be used as a final product (tattoo) on which clear marks, letters, figures, or patterns are displayed. For example, an inner pot for a heating cooker can be easily obtained, and there is no risk that the coating layer or display will peel off during use.

Claims (4)

[Claims] (1) An opaque colored coating layer is formed on a metal plate, a display layer with characters, figures, patterns, etc. different from the coloring is formed on the colored coating layer, and a clear coating layer is further formed on the display layer. A colored metal plate for plastic processing that is provided with a fluororesin coating layer. (2) The colored metal plate for plastic working according to claim (1), wherein the opaque colored coating layer contains mica or metal powder with a particle size of 5 μm or more. (3) The opaque colored coating layer contains titanium oxide, carbon black, phthalocyanine blue, or red iron oxide with a particle size of 1 μ or less (1)
) The colored metal plate for plastic working described in item 2. (4) A cooking device body formed by plastically working the colored metal plate for plastic working described in claims (1) to (3).