JPH069909B2 - Fluorine resin coating for pot inside rice cooker - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fluororesin coating for rice cooker inner pots such as jar rice cookers, heat retaining jars, rice cookers, and glutinous rice cookers.

"Prior art" There were three main prior arts in this field.

A technology to obtain a rice cooker inner pot by etching the surface of aluminum or aluminum alloy, then applying a tetrafluoroethylene resin (PTFE) dispersion, baking it dry, and press-molding.

After etching on the surface of aluminum or aluminum alloy, tetrafluoroethylene-ethylene copolymer (ET
FE) A technology to obtain a rice cooker inner pot by laminating a film and then press forming. Since the rice in such a rice cooker is apt to stick, the surface is coated with the above-mentioned fluororesin.

Among them, ETFF was poor in heat resistance, and thus was real.

In addition, a technology that puts a filler such as carbon into PTFE.

"Problems to be Solved by the Invention" However, the conventional techniques have the following problems.

B) PTFE or ETFE is a soft resin and is translucent or transparent, so it has the problem of being easily scratched and discoloration of aluminum due to the permeation of steam etc. during use of the rice cooker. The life of the vessel was limited.

B is non-adhesive and corrosion resistant (pinholes tend to occur)
It was inferior in that it was not used in the rice cooker field.

In view of the above, the present invention was developed to solve such problems.

[Means for Solving the Problems] That is, the present invention provides a fluororesin layer containing a filler for coloring or hiding an underlayer as a first layer on the surface of aluminum or an aluminum alloy, and further forming a first layer on the first layer. A fluororesin layer containing substantially no filler is provided as two layers, and at least mica and an organic filler are included as the filler of the first layer, and the mica is 0.5% by weight or more based on the fluororesin.
The content of the organic filler is 10% by weight or less, and the organic filler is any one of polyamide imide (PAI), polyimide (PI), polyphenylene sulfide (PPS), and polyether sulfone (PES), or a mixture thereof. On the other hand, it is a fluororesin coating for an inner pot of a rice cooker such as a jar rice cooker characterized by containing 0.1% by weight or more.

The term "substantially containing no filler" means that the amount of the filler is less than 0.5% by weight based on the fluororesin.

The present invention will be described in detail below.

The present inventors have completed the present invention as a result of intensive studies to solve the above problems.

That is, as illustrated in FIG. 1, the present invention is characterized in that two layers of fluororesin layers are provided on the surface of aluminum (hereinafter, including aluminum alloy) (3), and the first layer (1) is made of the base aluminum. A fluororesin layer containing a filler is provided for the purpose of coloring or concealing the base, and also for abrasion resistance (scratch resistance). Further, the second layer (2) contains substantially no filler (the fluororesin is not included). (Less than 0.5% by weight) is to provide a fluororesin.

In Fig. 1, (4) is a fluororesin, (5) is mica,
(6) is, for example, polyamide-imide, and (7) is a fluororesin.

That is, it is necessary to solve the appearance problem such as discoloration of aluminum in the first layer and the mechanical problem such as scratches of the fluororesin, and further to provide the surface non-tackiness in the second layer.

"Function" First, as the filler of the first layer, which will be described later in detail, at least mica of an inorganic filler and an organic filler are included, and the organic filler is polyamide-imide (PAI), polyimide (PI), Either polyphenylene sulfide (PPS) or polyether sulfone (PES) alone or a mixture thereof is used.

The filler is considered from the purpose of the invention and the following points are taken into consideration.

There is no problem in food hygiene.

A material that is easy to apply, that is, that is easily dispersed in the fluororesin, specifically, a material having a specific gravity of 6 or less is preferable.

By mixing such a filler with a fluororesin, the resin is colored and the discoloration of aluminum is made inconspicuous or the base is hidden (the mica of the inorganic filler is colored by itself, so that the PAI of the organic filler, etc. is By its own coloring or coloring at the sintering temperature of the fluororesin), and also by this filler the abrasion resistance is improved.

Further, as the second layer, a fluororesin which does not substantially contain a filler is required in order to improve non-adhesiveness. In other words, in the past, in the coating of fluororesin on a frying pan, etc., the one with a filler in the outermost layer is often used, but in the rice cooker field, compared to frying pans that cook with oil or water, rice is of a higher quality than rice. Since the tackiness is required, the second layer needs a fluororesin substantially containing no filler.

There are many types of mica (mica), which is the inorganic filler of the first layer, depending on the contained components, but a typical composition formula of mica is Mascovite (muscovite) K ₂ Al ₄ (Si ₃ Al). ) ₂ O ₂₀ (OH) ₄ Phlogopite (phlogopite) K ₂ Mg ₆ (Si ₃ Al) ₂ O ₂₀ (OH) ₄ Biotite (biotite) K ₂ (MgFe ²⁺ ) ₆ (Si ₃ Al) ₂ O ₂₀ (OH) _{4 and the} like, and any of them may be used.

In addition, titanium may be coated on the mica in order to give a bright appearance.

Next, the amount of mica to be filled is preferably 0.5% by weight or more and 10% by weight or less with respect to the fluororesin.
If it is less than 0.5% by weight, the effect of the present invention becomes small because the hiding property of the base is poor and the effect of improving wear resistance is small.

On the other hand, if it exceeds 10% by weight, it will be difficult for the anchor on the etched surface of the underlayer to penetrate into the anchor, and the adhesion to the aluminum surface of the underlayer will be poor, such being undesirable.

Next, as the organic filler, polyamide imide, polyimide, polyphenylene sulfide, or polyether sulfone having heat resistance that can withstand the baking temperature of 380 ° C. to 400 ° C. which is the baking temperature of the fluororesin is preferable. You may use these individually or in mixture.

These organic fillers have the effect of improving the adhesion of the base in addition to hiding the base and improving the wear resistance. That is, since these have good adhesiveness to the aluminum surface, when they are used together with the inorganic filler, the decrease in adhesiveness due to the addition of the inorganic filler can be suppressed.

Therefore, both mica and the above organic heat resistant resin should be
Most preferably, it is added as a layer. Among these, polyamide-imide is preferable as the organic heat-resistant resin in terms of abrasion resistance and corrosion resistance.

The organic filler exhibits the above effects when used in combination with the inorganic filler mica.
0.1% by weight or more is preferable, and if less than 0.1% by weight, the color hiding is insufficient.

Next, an embodiment of the present invention will be described.

Aluminum is usually roughened by etching or sandblasting, but the former etching (electrochemical treatment or chemical treatment) produces fine irregularities on the aluminum surface, which allows adhesion due to the anchor effect. Is more preferable.

On this surface, a fluororesin containing the filler of the present invention is applied as a first layer. Examples of the coating method include spray coating, roll coating and spin coating, but any method may be used. After coating, there is a method of only drying the water or heating to the baking temperature (380 to 400 ° C.) of the fluororesin, but either method may be used.

Next, this surface is coated with a fluororesin containing substantially no filler, and this method may be any method similar to that of the first layer.

The fluororesin used here is tetrafluoroethylene resin (PT
FE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) are preferable, and these are used alone or in combination. Good.

Further, the thickness of the coating film is preferably 20 μm to 35 μm in total for the two layers. If it is less than 20μ, pinholes are likely to appear and 3
If it exceeds 5 μ, cracks are likely to occur after coating.

"Examples" Examples of the present invention will be described below.

Example 1 An aluminum material having a plate thickness of 2.5 mm (ASB material manufactured by Kobe Steel, Ltd.) was used.

First, using this as an anode, an electrochemical and etching treatment was performed in an aqueous ammonium chloride solution at an electric quantity of 25 coulomb / cm ² to form fine irregularities on the surface. This surface was coated with the resin mixture shown in Table 1 as the first layer and baked, and then the second layer further contained a filler-free PTFE dispersion (D-1 manufactured by Daikin Industries, Ltd.).
F) was coated, the water was dried, and then baked at 400 ° C. for 10 minutes. The resin layer of this was coated such that the first layer and the second layer each had a thickness of 15 μm and a total of 30 μm.

The coated plate thus obtained was processed by press molding to obtain the rice cooker of the present invention.

On the other hand, as a comparative example, the same etching plate as in the above method was filled with only the second layer (D-1F only), or the first layer (same as Example 1-1), or the filling of the first layer. The agent was an organic filler only, and the first and second layers were coated with about 30 μm, and baking press processing was carried out by the same method.

The following items were implemented as the evaluation method of the thus obtained rice cooker.

Discoloration during practical use: 300 rice cooked using a commercially available rice jar
The occurrence of repeated discoloration was investigated.

Abrasion resistance: This test method is as follows. 100 mmφ from the cover plate
Punch out the test piece. Heat this test piece,
A stainless steel scrubbing (trade name: Hypicalon Jumbo Scrubbing # 60) is pressed against this coated surface with a load of 2 kg.

Next, 200 r. p. A rotation wear test is performed at a rotation speed of m, and the number of wear is defined when the aluminum surface having metallic luster is exposed.

Adhesion: The edge of the coating that reaches the base with a knife (1 mm
Space 100), put cellophane tape on this side, and immediately pull it off. Repeat this 20 times, 1
Count the remaining number of the resin of 00 Mas.

Non-adhesiveness: According to the sticking test of sugar (see FIG. 2) A stainless ring (11) having an inner diameter of 25.4 mm is placed on the evaluation sample (12), and sugar (13) is put thereinto and melted. After cooling, the ring spring (14) is set and the load F (kg) when the tension ring is separated from the sample in the horizontal direction is measured. The better the non-adhesiveness, the smaller the load at this time.

Corrosion resistance: 25 g of commercially available "Oden no Motomoto" is dissolved in 1 water, and the cut piece is put in this and heated at 90 to 100 ° C for 100 hours. After this, it is taken out and checked for corrosion from the coating surface.

These results are summarized in Table 1.

As can be seen from the above Examples and Comparative Examples, it can be seen that the discoloration and abrasion resistance (scratch resistance) of aluminum are extremely superior to those of Comparative Example 1 (conventional product).

Further, Comparative Example 2 shows the case where the rice cooker is used only in the first layer of Example 1-1, but the non-stickiness and the corrosion resistance are higher than those of the conventional products.

Furthermore, in Comparative Examples 3, 4, and 5, the inorganic filler mica was not used as the filler of the first layer, and only the organic filler was used.
The case of using a rice cooker having two layers is shown, but as can be seen from these comparative examples, by adding both mica and an organic filler, there is a dramatic wear resistance effect that is not an addition effect.

Example 2 Next, mica and polyamideimide (PA
The composition of both of I) was changed as shown in Table 2, and the fluororesin containing both of them was evaluated in the same manner as in Example 1 using the same aluminum plate as in Example 1-1.

[Advantages of the Invention] As described above, according to the present invention, the problem of discoloration of aluminum due to the permeation of steam or the like during use of a rice cooker, the problem of abrasion (scratch), etc. was solved, and at the same time, non-adhesiveness was excellent. A fluorine resin coating for a rice cooker pot is obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a cross section of a coating of the present invention, and FIG. 2 is an explanatory diagram of a non-sticking evaluation method by a sugar sticking test in an example of the present invention. (1) ... First layer, (2) ... Second layer, (3) ... Aluminum or aluminum alloy, (4) ... Fluorine resin, (5) ... Mica, (6) ... Polyamideimide resin, (7) ... Fluorine resin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-31447 (JP, A) SAIKAI Shou 62-9524 (JP, U) JP-B 59-43226 (JP, B2)

Claims (1)

[Claims] 1. A surface of aluminum or an aluminum alloy is provided with a fluororesin layer containing a filler for coloring or hiding an underlayer as a first layer, and a filler is substantially provided as a second layer on the first layer. A fluorine resin layer not containing is provided, and at least mica and an organic filler are included as a filler for the first layer, and the mica is 0.5% by weight or more with respect to the fluorine resin.
The content of the organic filler is 0% by weight or less, and the organic filler is polyamide imide (PAI), polyimide (PI), polyphenylene sulfide (PPS), or polyether sulfone (P).
ES) alone or in a mixture thereof, and containing 0.1% by weight or more with respect to the fluororesin, a fluororesin coating for an inner pot of a rice cooker such as a jar rice cooker.