JPS604755B2 - Fluorine resin coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluororesin coating method as a surface treatment method for electric pots and the like.

Conventionally, the following method has been used to coat the surface of a base material made of aluminum or aluminum alloy, such as an electric pot, with a fluororesin.

For items that use oil during cooking, such as frying pans and hot plates, and are not susceptible to corrosion due to water, roughen the surface of the base material with alumina blasting, etc., then form a fluororesin layer as a primer and top coat. Two-layer coating.

'B} For those that mainly use water for boiling, such as electric pots and skillets, the surface of the base material is made rough by alumina blasting, etc., and then polyphenylene sulfide resin, primer, and fluororesin are sequentially applied and fired to form a film. form.

However, with method (■) there is a risk of corrosion due to the large number of pinholes that are a characteristic of fluororesin coatings, while with method 'B'', the risk of corrosion is reduced, but the aqueous solution penetrates through the fluororesin coating and damages the base material. The polyphenylene sulfide resin accumulates between the eyebrows, expands due to rapid energization drying, lifts the fluororesin film and swells, resulting in so-called pristar.

Another method for preventing such blisters is to apply a two-layer coating of brimer and fluororesin to the 'CI base material, which has many pinholes, to allow moisture that has penetrated through the pinholes to escape.

■ Create an alumite film on the surface of the base material, apply and bake polyphenylene sulfide resin, primer, and fluororesin in sequence without sealing, and let the polyphenylene sulfide resin enter the alumite film into the pores of the alumite film. How to combine.

{E' Create an alumite film on the surface of the base material, perform pore sealing treatment, apply polyphenylene sulfide resin, primer, and fluororesin sequentially and bake. During baking, process at 400°C for 10 minutes or more to crack the alumite film and form polyphenylene. A method of injecting sulfide resin into cracks and bonding.

However, all of these methods were insufficient as countermeasures against pristar.

The reason for this is explained with reference to Fig. 1, which shows the surface treatment performed using the leg method.
C forms a fine surface b cut into a sawtooth shape, and this rough surface b
Forming a polyphenylene sulfide resin film c on top,
Furthermore, a fluororesin film d consisting of a primer and a top coat is formed, and a polyphenylene sulfide resin film c
A part e of the rough surface b is cut into the recess f of the model.

Therefore, when pulled in the horizontal plane direction, part e of the film c bitten into the recess f engages and exhibits strong adhesion, but the rough surface b
This is because when water enters between the film c and the film c and expands, it is difficult to engage them if a tensile force is applied in the vertical direction. The present invention has been made in view of the above-mentioned drawbacks, and involves etching the surface of a base material made of aluminum or aluminum alloy by chemical means to form a rough surface consisting of a large number of concave holes that are bent inwardly. By forming a polyphenylene sulfide resin film on this rough surface, a part of this film was engaged with a large number of concave holes that were bent on the inside, and penetration through the pinholes of the fluororesin film formed on the surface was caused. This prevents blistering when water expands. Next, an example of implementation of the present invention will be described with reference to FIGS. 2 and 3.

1 is a base material made of aluminum or aluminum alloy casting constituting electric steel or skilet; heating element 2;
is attached by means such as plating, crimping, and caulking.

3 is a rough surface formed by etching, and the base material 1
By immersing the surface of the base material 1 in an aqueous solution of 15% hydrochloric acid for 5 to 1 minutes, a large number of 5 to 15 inwardly curved recesses 4 are formed on the surface of the base material 1, and a rough surface 3 is formed. configured.

Next, a polyphenylene sulfide resin film 5 is formed by applying polyphenylene sulfide resin to a thickness of 20 mm to 40 mm on the surface of this rough surface 3 and baking it.
A portion 6 of this coating 5 bites into the bent recess 4 of the rough surface 3 and engages with it. Next, a primer made of an adhesive containing a fluororesin is applied and baked on the surface of the film 5, and then a fluororesin is applied and baked to form a fluororesin film 7 made of the primer and the fluororesin. Next, the operation of this embodiment will be explained.

When moisture permeating through the pinholes of the fluororesin film 7 on the surface thermally expands between the base material 1 and the polyphenylene sulfide resin film 5, a portion 6 of the polyphenylene sulfide resin film 5 is inside the base material 1. Since it engages with the bent recessed hole 4, blistering is prevented, and since the polyphenylene sulfide resin film 5 and the fluororesin film 7 have good bonding properties, they are difficult to peel off.

Although the above embodiment is one method, it is also possible to create irregularities of about 5 mm by etching, which is known in the art.

This typical method uses an alkaline agent-acid treatment method to
It is carried out using 25 w/v% sodium hydroxide, and a liquid temperature of 5000 to 90 qC and a time of 20 to 4 cc are sufficient. According to the present invention, since the surface of the base material made of aluminum or aluminum alloy is etched to form a rough surface, the phase surface formed by the etching process has a large number of inwardly curved concave holes. Therefore, the polyphenylene sulfide resin film that is next formed in this recessed hole engages with the bent part inside this recessed hole, and blistering also occurs when moisture that has entered through the surface fluororesin film expands thermally. Never. Next, test examples of the present invention will be shown.

Test example 1 Sample: The conventional product is an electric pot made of aluminum base material.
The product of the present invention is an electric pot made of an aluminum base material that is treated with a fluororesin by the method described in Example 1.

Test method: Put 1,300 cc of water and 25 oz of commercially available oden stock into an electric pot, heat at 80 qo ± 1,000 for 8 hours, then leave at room temperature for 8 hours, and after draining the contents, the temperature rises rapidly to 200℃. Warm and dry with electricity. This operation was repeated three times and the surface condition of the pot was observed each time. The results are shown in Table 1. Table 1 Blisters: Shows the blisters of the fluororesin film that occurred on the surface of the coin, and shows their size and number.

From Table 1 above, it is clear that the product of the present invention can withstand repeated use, compared to the conventional product, which swells from the second use. Test Example 2 Sample: A sample having the same specifications as Test Example 1 was used.

Test method: Water containing 30% rice bran by volume was placed in an electric pot, heated and boiled for 5 hours, then the contents were drained and dried at 20,000 ℃. Table 2 shows the results of observing the surface condition of this pot. Table 2 As shown in Table 2 above, all of the conventional products have blisters, but none of the products of the present invention have any abnormality.

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[Brief Description of the Drawings] Fig. 1 is an enlarged sectional view of a part of an electric pot that has been surface-treated by a conventional method, and Fig. 2 is a longitudinal sectional front view of an electric pot that has been surface-treated by the method of the present invention. FIG. 3 is an enlarged sectional view of a portion of the same. 1...Motomura, 3...Kumen, 5...
Polyphenylene sulfide resin film, 7...Fluororesin film. Bri' figure night 2 figure me 3

Claims (1)

[Claims] 1. Etching the surface of a base material made of aluminum or aluminum alloy by chemical means to form a rough surface, then forming a polyphenylene sulfide resin film on this rough surface, and then forming a fluororesin film. A fluororesin coating method characterized by: