JPH1071672A - Coated metallic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated metallic sheet which is excellent in heat resistance, food contamination resistance, and adhesion and decorative design properties of a film. SOLUTION: An under coat layer 3 and a top coat layer 4 are formed on a metallic base sheet 1. The under coat layer 3 is composed of two layers such as a lower layer 3a and an upper layer 3b. The lower layer 3a has polyether sulfone resin as a main component. The upper layer 3b has polyether sulfone resin containing coloring pigment as a main component. The top coat layer 4 is formed of clear coating wherein 10-100 pts.wt. of tetrafluoro-resin is blended in 100 pts.wt. of polyether sulfone resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various cooking utensils, such as wall plates such as gas cooktops and side plates, inner and outer wall plates of gas ranges and microwave ovens, bakeware and used oil pots, and household appliances. The present invention relates to a coated metal sheet that can be suitably used as a heat-resistant component of a device or the like.

[0002]

2. Description of the Related Art As a coated metal plate of this type, for example, as shown in FIG. 2, a stainless steel substrate 1 is made of polyether sulfone resin (PES) 100 parts by weight, and about 50 parts by weight of polytetrafluoroethylene (PTFE). A coating film 2 is formed by applying and baking a coating material containing 50 to 200 parts by weight of a color pigment and 50 to 200 parts by weight of a coloring pigment (literature unknown). PES
Is used for improving heat resistance, PTFE is used for imparting surface lubricity, and a coloring pigment is used for coloring design purposes.

[0003]

However, in the above-mentioned coated metal plate, PES, PTF
E and the coloring pigment are all contained together, so that during the baking of the paint, the PTFE is prevented from floating toward the coating film surface by the coloring pigment contained in the same paint. . As a result, sufficient lubricity cannot be imparted to the surface of the coating film. It was not enough to improve the performance.

[0004] PTFE is excellent in lubricity but has poor adhesion to a metal plate. Therefore, if the PTFE does not float on the surface of the coating film but remains in the lower layer of the coating film on the side in contact with the stainless steel substrate 1 as described above. This lowers the adhesion to the stainless steel substrate 1 and causes peeling of the coating film. Furthermore, since the coloring pigments rise to the surface of the coating film to increase the surface roughness, there is also a problem that in this respect, seizure also occurs, making it difficult to wipe off foods.

Accordingly, an object of the present invention is to provide a coated metal sheet which is excellent in heat resistance, food stain resistance, coating film adhesion and design.

[0006]

The coated metal sheet of the present invention comprises:
An undercoat layer 3 and an overcoat layer 4 are formed on a metal substrate 1. The undercoat layer 3 is composed of a lower layer 3a containing a polyether sulfone resin containing a rust-preventive pigment as a main component and a polyether sulfone containing a color pigment. An upper layer 3b mainly composed of a resin, and as the overcoat layer 4, a clear layer formed by mixing 10 to 100 parts by weight of a tetrafluorinated fluororesin with respect to 100 parts by weight of a polyether sulfone resin. It is.

[0007] Aluminum powder or pearl powder can be appropriately compounded in the overcoat layer 4. The overcoat layer 4
0.01 to 30 parts by weight based on 100 parts by weight of the resin component in the paint.
A part by weight of a coloring pigment can be contained.

[0008]

Since the upper layer 3b of the undercoat layer 3 contains a coloring pigment, a coloring effect is exhibited even if the clear overcoat layer 4 does not contain a coloring pigment. Since it is not necessary for the clear overcoat layer 4 to contain a coloring pigment, a tetrafluoride-based fluororesin can sufficiently float on the surface of the overcoat layer 4 to provide a surface having excellent lubricity. Smoothness can be maintained without projecting to the surface. As described above, since the surface can be sufficiently lubricated, not only the food contamination resistance, but also the mold has good slipperiness during press working and is excellent in moldability. Undercoat 3 Undercoat 3
Since a is not mixed with tetrafluoride-based fluororesin having poor adhesion to metal, the adhesion to the metal substrate 1 is improved.

Since the lower layer 3a of the undercoat layer 3 contains a rust-preventive pigment, the rust-preventing effect of the metal substrate 1 is enhanced. Since no coloring pigment is contained in the overcoat layer 4, even if aluminum powder or pearl powder is blended in the overcoat layer 4 in order to give a metallic feeling, a floating action of the tetrafluorinated fluororesin on the coating film surface is achieved. Is not much disturbed. Therefore, various design feelings can be obtained.

When aluminum powder or pearl powder is blended into the clear overcoat layer 4, even a small amount of powder can achieve metallic toning. When the overcoat layer 4 contains 0.01 to 30 parts by weight of the color pigment based on 100 parts by weight of the resin component in the paint, a color synthesized with the color of the color pigment of the overcoat layer 3 can be obtained.

The undercoat layer 3 is formed of two layers: a lower layer 3a mainly composed of a polyether sulfone resin containing a rust preventive pigment, and an upper layer 3b mainly composed of a polyether sulfone resin containing a color pigment. By doing so, the color pigment and the rust-preventive pigment are not mixed together, so that the layer has a cross-sectional structure. Elimination of the problem that colors (mainly yellow-based ones) are mixed and turbid, making it difficult to obtain a desired clear color. Therefore, it is particularly advantageous when a white clear color is to be obtained. By not mixing the coloring pigment and the rust-preventive pigment together, a coloring effect and a rust-preventing effect can be sufficiently imparted, and various measures can be taken with respect to toning and rust prevention.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a metal substrate 1 may be various metal plates, but preferably aluminum plate, stainless steel plate, aluminum-plated steel plate and Zn-AI alloy-plated steel plate in consideration of heat resistance. Thicknesses of about 0.3 to 1.5 mm are often used. The metal substrate 1 is subjected to a surface treatment such as a chromate treatment before painting.

An undercoat layer 3 is formed on a metal substrate 1. The undercoat layer 3 includes a lower layer 3a mainly composed of a polyether sulfone resin (PES) containing a rust-preventive pigment, and an upper layer 3b mainly composed of a color pigment.

As the color pigment to be incorporated in the upper layer 3b of the undercoat layer 3, a calcined pigment which does not discolor even at a high temperature, specifically, TiO ₂ -BaO-NiO, TiO ₂ -CoO-NiO-ZnO, CuO-Fe ₂ O
_{Use 3-} Mn ₂ O ₃ type pigment or the like.

As the rust-preventive pigment to be incorporated in the lower layer 3a of the undercoat layer 3, there are leadtan, zinc chromate and the like, and strontium chromate is preferred. Strontium chromate does not deteriorate even when used at a high temperature of 300 ° C., and retains sufficient corrosion resistance. Strontium chromate is blended in the lower layer 3a of the undercoat layer 3 at a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of PES. 10
If the amount is less than 50 parts by weight, the corrosion resistance is inferior, and if it exceeds 50 parts by weight, the processability is inferior.

The thickness of each of the lower layer 3a and the upper layer 3b in the undercoat layer 3 is 3 to 20 μm. If the thickness is less than 3 μm, the color of the upper layer 3b will not be produced, or the lower layer 3a
This is because the rust-preventing power of the steel is poor, and if it exceeds 20 μm, the cost increases. The baking temperature of the undercoat layer 3 is 2
Set to 40-300 ° C.

An overcoat layer 4 is formed on the undercoat layer 3.
The overcoat layer 4 is 10 to 100 parts by weight of a tetrafluorinated fluororesin with respect to 100 parts by weight of PES. If the amount of the tetrafluoride-based fluororesin is less than 10 parts by weight, no improvement in food stain resistance is observed. If the amount exceeds 100 parts by weight, the dispersibility of the paint becomes poor, making it difficult to apply the paint. Decrease. Practically, it is 40 to 80 parts by weight.

Examples of the tetrafluorinated fluorine resin include polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-per-fluoroalkylvinyl ether copolymer (PFA), A fluoroethylene-hexafluoropropylene copolymer (FEP) or the like is used.

The baking temperature of the overcoat layer 4 is 300 to 420.
Set to ° C. When using PTFE at the time of this baking,
Only this PTFE separates and floats on the surface to form a thin lubricating layer. The thickness of the overcoat layer 4 is 0.1 to 2
0 μm. If the thickness is less than 0.1 μm, no improvement in food stain resistance is observed. If it is 20 μm or more, the cost increases.

Aluminum powder or pearl powder can be blended in the overcoat layer 4, and in this case, the resin content in the paint is 10%.
1 to 50 parts by weight with respect to 0 parts by weight. When aluminum powder or pearl powder and a color pigment are blended, the total amount is 1 to 50 parts by weight based on 100 parts by weight of the resin component.

Example 1 A 55% aluminum-zinc alloy-plated steel sheet was used as the metal substrate 1, and a surface-treated film was formed by a coating type chromate treatment (Alodine NRC300, manufactured by Nippon Paint Co., Ltd.). On the surface of the metal plate 1, a lower layer (5 μm thick) containing 50 parts by weight of strontium chromate (rust preventive pigment) in 100 parts by weight of PES, and Cu in 100 parts by weight of PES
An undercoat layer 3 consisting of two layers, an upper layer (8 μm thick) containing 100 parts by weight of an O—Fe ₂ O ₃ —Mn ₂ O ₃ color pigment, was baked at 300 ° C. and dried. Further, on the undercoat layer 3, a clear paint containing 60 parts by weight of PTFE with respect to 100 parts by weight of PES was applied and baked to form an overcoat layer 4 having a thickness of 7 μm.

Comparative Example 1 A stainless steel (SUS430) steel plate was used for the metal substrate 1 and a coating type chromate treatment (manufactured by Nippon Paint Co., Ltd.):
A surface treatment film was formed with Alodine NRC300). On the surface of the metal substrate 1, 50 parts by weight of PES and CuO-Fe ₂ O
_A paint comprising 100 parts by weight of a _3- Mn ₂ O ₃ -based color pigment and 50 parts by weight of PTFE is applied and baked at 400 ° C. for 15 minutes.
A μm thick coating was formed.

Comparative Example 2 100 parts by weight of PES and CuO-Fe ₂ O
100 parts by weight of _3- Mn ₂ O ₃ based color pigment and 10 parts of PTFE
Comparative Example 1 was carried out in the same manner as in Comparative Example 1 except that a paint consisting of 0 parts by weight and 30 parts by weight of aluminum powder was applied and baked at 400 ° C. to form a 15 μm thick coating film.

Comparative Example 3 The same operation as in Comparative Example 1 was carried out except that a 55% aluminum-zinc alloy-plated steel sheet was used as the metal substrate 1.

Each performance test was performed on the coated metal sheets obtained in each of the above Examples and Comparative Examples. Table 1 shows the results.

[0026]

[Table 1]

The method of each test and the method of evaluation will be described below. (1) Food contamination resistance test Soy sauce, on a test piece heated at 250 ° C for 500 hours,
Apply food such as sauce, lemon juice, milk, and 300 ℃
After baking for 1 hour at room temperature, the temperature was returned to normal temperature, and the deposits were peeled off. At this time, the degree of ease of peeling off the deposits and the degree of contamination of the coating film were observed. ◎ indicates that peeling was extremely easy and no contamination was observed, and ○ indicates that peeling was somewhat easy and no contamination was clearly observed. X indicates that the peeling is impossible, or even if it is extremely difficult, the peeling is possible, but considerable contamination is recognized. (2) Salt spray test A 5% salt spray test is performed continuously for 240 hours to evaluate the degree of corrosion. (3) Scratch test A coin scratch test was performed at room temperature, and the surface was visually observed. ◎ indicates almost no damage, ○ indicates slight damage, and × indicates that the coating film was continuously peeled off from the metal substrate 1.

(1) Results of Food Pollution Resistance Test and Surface Appearance In Example 1, since the overcoat layer 4 contains no coloring pigment or aluminum powder, PTFE sufficiently floats on the surface to form a thin lubricating layer. Very good resistance to food contamination. On the other hand, in Comparative Examples 1 and 3, since the color pigment and the aluminum powder were mixed, the PTFE was coated on the metal substrate 1.
It remains toward the lower layer on the side in contact with and has poor food contamination resistance.
In Comparative Example 2, the food stain resistance was poor as in Comparative Examples 1 and 3, and the surface appearance was inconspicuous because the metallic powder of the aluminum powder was erased by the coloring pigment.

(2) Results of Salt Spray Test In Example 1, the metal substrate 1 has a lower corrosion resistance than stainless steel.
Although it is a 5% aluminum-zinc alloy-plated steel sheet, since the lower layer 3a of the undercoat layer 3 contains a rust preventive pigment, the metal substrate 1 hardly generates rust and has good corrosion resistance. On the other hand, in Comparative Examples 1 and 2, since the metal substrate 1 was stainless steel (SUS430), the corrosion resistance was good. However, in Comparative Example 3, 55%
Since an aluminum-zinc alloy-plated steel sheet was used and no rust preventive pigment was blended in the undercoat layer, rust was slightly generated.

(3) Scratch test result In Example 1, the lower layer 3a of the undercoat layer 3 did not contain PTFE having poor adhesion to the metal substrate 1, so that the coating film was hardly peeled off, and 55% Since an aluminum-zinc alloy-plated steel sheet is used, the adhesiveness with paint is very good as compared with a stainless steel plate. On the other hand, in Comparative Examples 1 and 2, P having poor adhesion to the metal substrate in the coating film.
Since TFE was incorporated and the metal substrate was a stainless steel plate having poor adhesion to the paint, the coating film was easily peeled off. Comparative Example 3 was slightly better because a 55% aluminum-zinc alloy-plated steel sheet having good adhesion to paint was used as the metal substrate.

[0031]

As described above, according to the present invention, the heat resistance, the food stain resistance, the adhesion of the coating film, the corrosion resistance are excellent, and the design that various toning is possible is also excellent. It is useful for heat-resistant components such as various cooking utensils and home appliances. In particular, in the present invention, the undercoat layer 3 has a two-layer structure of a lower layer 3a containing a rust preventive paint and an upper layer 3b containing a color pigment, and the rust preventive paint and the color pigment are not mixed. A coated metal plate exhibiting an effective coloring effect in design can be obtained while ensuring the properties.

[Brief description of the drawings]

FIG. 1 is a sectional view of a coated metal plate according to the present invention.

FIG. 2 is a sectional view of a conventional painted metal plate.

[Explanation of symbols]

 Reference Signs List 1 metal substrate 3 undercoat layer 3a undercoat layer underlayer 3b undercoat layer upper layer 4 overcoat layer

Claims (3)

[Claims] An undercoat layer is formed on a metal substrate, and an overcoat layer is formed on the undercoat layer. The undercoat layer is made of a polyether sulfone resin containing a rust-preventive pigment. Lower layer 3a mainly composed of a main layer and upper layer 3b mainly composed of a polyether sulfone resin containing a coloring pigment
Wherein the overcoat layer 4 is formed of a clear paint in which 10 to 100 parts by weight of a tetrafluoride-based fluororesin is blended with respect to 100 parts by weight of the polyether sulfone resin. Board. 2. The coated metal sheet according to claim 1, wherein the overcoat layer 4 contains aluminum powder or pearl powder. 3. The coated metal sheet according to claim 1, wherein the overcoat layer 4 contains 0.01 to 30 parts by weight of a coloring pigment based on 100 parts by weight of the resin component in the paint.