JP2010022447A - Cooking pot of electromagnetic induction cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooking pot for an electromagnetic cooker which has high heating property and excellent cooking performance. <P>SOLUTION: Surface roughening treatment 8 is applied to a surface of a magnetic metal layer 5. A heat insulation layer 10 having a heat conductivity of one fifth or lower of a magnetic metal material is arranged on the outer surface of the magnetic metal layer. Thereby, heating property of the magnetic metal layer 5 is improved and heat inside the cooking pot is prevented from escaping. Ceramics or a ceramics coating to which a filler is added for decreasing heat conductivity may be used as the heat insulation layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooking pan used in an electromagnetic induction cooker.

  Conventionally, cooking pans that are widely available to the general public are manufactured using aluminum, stainless steel, titanium, iron, copper, or a combination of these as a base material.

  In particular, in cooking pans used in electromagnetic induction cookers, magnetic metal such as ferritic stainless steel is placed on the outer layer of the pan base material, and aluminum is laminated on the inside, or in some cases, stainless steel is further laminated on the inner surface. There are things that are doing.

  As a characteristic of the electromagnetic induction cooker, a highly magnetic material is more advantageous for heat generation due to electromagnetic induction. Therefore, magnetic metal such as ferritic stainless steel is often used for the outer layer of the pan. For the inner layer, aluminum having a high thermal conductivity is often used for the purpose of quickly heat-diffusing and uniformly heating the food.

  Furthermore, these metal cooking pans are treated with a fluororesin coat on the inner surface in order to prevent the food from sticking strongly, thereby improving the non-adhesiveness to the food.

  The fluororesin coat to be treated on the inner surface of the cooking pan is usually one having a one-layer structure, or two or more layers, but it has good non-stickiness, high durability and good From the viewpoint of obtaining a good appearance, it is preferable to form a fluororesin coat having two or more layers.

  In conventional cooking pots for electromagnetic induction cookers, it has been pointed out that the heat generation is further improved, and as a means for improving the heat generation from the material side of the cooking pot, a material having a high relative permeability is used, or a specific material is used. It is an effective means to use a material having a high resistance value.

  From these viewpoints, ferritic stainless steel typified by SUS430 has been often used as the magnetic metal in the heat generating layer of the cooking pot of the electromagnetic induction cooker.

  In addition, there were cases where iron alloys such as permalloy were used and cases where copper plating was applied to the outer surface of the magnetic metal layer.

  However, in these materials, the specific resistance value and relative permeability, which are factors that determine the electromagnetic induction heat generation characteristics, are fluctuation factors at the time of molding, but are stable as factors inherent to the material after molding to the cooking pot. Therefore, there was a limit to improving the heat generation from the material side.

  In addition, improving cooking performance is a major issue in cooking pans. Conventional cooking pans have been designed to increase the thickness of the base material in order to distribute heat uniformly, or to stack the base material in multiple layers. There was a case that I did.

  However, from the viewpoint of improving the taste of the cooked food, it is one of the important conditions to make the cooking pot thicker or multi-layered to make the heat circulation uniform. It is also an important condition in terms of improving the taste to take a configuration in which the heat generated in the magnetic metal layer is transferred to the cooking pan without escaping.

As an example so far, there is one that has a heat insulating layer on the outer surface of the cooking pan, but it is difficult to improve the taste by simply providing a heat insulating layer on the outer surface of the cooking pan. Since the hollow member is contained, the adhesion between the resins is low, the heat insulating layer is brittle, and durability such as wear resistance is low (see, for example, Patent Document 1 and Patent Document 2).
JP-A-10-211091 JP-A-11-56599

  The object of the present invention is to solve these conventional problems, providing means for improving the heat generation of the cooking pot material in order to improve the heat generation of the cooking pot of the electromagnetic induction cooker, and being cooked. In order to improve the taste of the cooked food, the present invention is to provide a cooking pan that is difficult to release heat and has high durability.

  In order to achieve the above-mentioned object, the present invention performs a roughening treatment on the surface of the magnetic metal layer and arranges a heat insulating layer having a thermal conductivity of 1/5 or less of the magnetic metal material on the outer surface. is there.

  Thereby, while being able to improve the exothermic property in a magnetic metal layer, it can be set as the structure which is hard to escape the heat in a cooking pan.

  Since the cooking pot for electromagnetic induction heating of the present invention can enhance heat generation by the above-mentioned means, it is possible to realize efficient electromagnetic induction heating and to make it difficult to release heat generated during cooking. The taste of cooked food can be improved.

  The first invention is a cooking pot for an electromagnetic induction cooker in which a surface of a magnetic metal layer is subjected to a roughening treatment and a heat insulating layer having a thermal conductivity of 1/5 or less of that of a magnetic metal material is disposed on the outer surface thereof. It is.

  More specifically, a ferritic stainless steel, which is a magnetic metal having excellent electromagnetic induction heat generation characteristics, or a multilayer such as a clad material obtained by joining a heat-conductive metal such as aluminum and ferritic stainless steel. The surface of the magnetic metal layer obtained by using metal as the base material for the cooking pan is subjected to surface roughening treatment so that the surface roughness Ra becomes 0.5 to 5 μm by shot blasting with alumina particles or the like. Carried out.

  Next, a heat insulating layer is formed on the surface of the roughened magnetic metal layer. Preferably, the thermal conductivity is set to 1/5 or less of the magnetic metal layer.

  For example, when the base material is aluminum and ferritic stainless steel, the thermal conductivity of the ferritic stainless steel is about 26 W / m · k, so that a heat insulating film of 5.2 W / m · k or less is provided. The thickness is preferably about 100 μm or more, and it is desirable to increase the thickness as it becomes the upper part of the cooking pan.

  Moreover, although the site | part which provides a heat insulation layer is essential for a cooking pan side surface part, regarding a bottom face part, it is arbitrary.

  In addition, you may process the fluorine resin coat for improving non-stickiness to the cooking pot inner surface.

According to this configuration, since the surface of the magnetic metal is roughened, the surface area that receives the magnetic force generated from the cooker is increased and the electrical resistance is increased. In addition, since the heat insulating layer is provided on the surface of the magnetic metal layer, the corrosion resistance of the magnetic metal layer can be prevented from being deteriorated due to roughening, and a highly durable cooking pan can be obtained.

  In addition, when a heat insulating layer having a low thermal conductivity is provided on the surface of the magnetic metal layer, it is difficult for the heat generated in the magnetic metal layer to escape to the outside, and the cooking result can be favorably affected.

  A second invention is a cooking pot characterized in that in the first invention, the heat insulating layer is ceramic, and roughens ceramic materials having excellent durability such as heat resistance. The outer surface of the treated magnetic metal layer is treated.

  As a method of treating the ceramic material on the outer surface of the cooking pan, there is a method in which the surface of the magnetic metal layer is roughened and then ceramic spraying is performed, and typical examples of the ceramic include alumina, zirconia, and chromia. .

  At this time, the ceramic layer may be sprayed directly on the roughened surface of the magnetic metal layer, but a metal layer having an intermediate coefficient of thermal expansion between the magnetic metal layer and the ceramic layer is used as a buffer layer against thermal expansion. It is desirable to spray about μm.

  With this buffer layer, the corrosion resistance of the magnetic metal layer can be secured, and the phenomenon that the ceramic layer peels off due to thermal expansion and contraction due to heating during cooking can be prevented.

  According to this configuration, since the surface of the magnetic metal is roughened, the surface characteristics of the magnetic metal are changed. As a result, the heat generation property of the magnetic metal layer is improved and the surface of the roughened surface is improved. Since the heat-resistant heat insulation layer with lower thermal conductivity than the material is provided, the heat generated in the magnetic metal layer is difficult to escape to the outside, which can have a positive effect on the cooking result, and the heat resistance of the heat insulation layer is also High heat deterioration due to cooking can also be suppressed.

  Moreover, it is possible to suppress the penetration of moisture and corrosion promoting substances into the ceramic layer by applying a heat-resistant coating such as epoxy, silicone, polyethersulfone, or fluororesin on the ceramic layer.

  In a third aspect of the invention, the heat insulating layer is a ceramic coat, and a filler that reduces thermal conductivity is added.

  More specifically, the ceramic coat contains a filler that reduces the thermal conductivity, such as hollow glass beads or porous carbon particles, and is characterized in that it is thickened.

  In the case of hollow glass beads, a magnetic metal having a roughened ceramic coating layer containing 10 to 50% by weight of a coating having an average particle size of 10 to 80 μm and a specific gravity of 0.05 to 0.5 g / ml It is desirable to provide 100 μm or more on the surface, and it is desirable to increase the thickness as it becomes the upper part of the pan.

  If the hollow glass beads are less than 10% by weight, the performance of sufficiently confining heat in the pan will not be exhibited, and if it exceeds 50% by weight, the coating film is brittle and does not function as a film, so 10 to 50% by weight is desirable. .

In addition, a protective coating layer can be provided as a second layer on the ceramic coating, but the filler for reducing the thermal conductivity such as hollow glass beads added to the protective coating layer is 10% by weight or less. Is desirable.

  This is because the purpose of improving the strength and protecting the ceramic coating of the first layer from abrasion and impact is higher than the purpose of lowering the thermal conductivity in the upper layer portion than the second layer.

  According to this configuration, since the surface of the magnetic metal is roughened, the surface characteristics of the magnetic metal are changed. As a result, the heat generation property of the magnetic metal layer is improved and the surface of the roughened surface is improved. Since the heat-resistant heat-insulating film having a lower thermal conductivity than the material is provided, it is difficult for the heat generated in the magnetic metal layer to escape to the outside, and the cooking result can be positively affected.

  For the purpose of improving the adhesion between the ceramic coating layer to which the filler for reducing the thermal conductivity is added and the base material, a thin primer layer may be provided between the roughened surface of the magnetic metal layer.

  Furthermore, when a large amount of filler, such as hollow glass beads, is added to the ceramic coating layer to reduce the thermal conductivity, the resin component in the coating is relatively reduced, protecting the ceramic coating layer from wear and impact. Therefore, securing the strength is a big problem.

  For this reason, by adding fine particles such as carbide particles, ceramic particles, glass particles, and diamond particles to the ceramic coating layer and its protective coating layer, the wear resistance is improved, and it becomes strong against indentation scratches and the like.

  In the fourth aspect of the invention, the thickness of the heat insulating layer increases as it becomes the upper part of the cooking pan.

  The thickness of the heat insulating layer is about 100 μm or less or about 0 μm for the bottom of the cooking pan, and the thickness of the side surface of the pan gradually increases toward the top. Thereafter, the average film thickness of the lower side surface is at least 100 μm or more, and the average film thickness of the upper half of the side surface (hereinafter, upper side surface) is in the range of 2 to 3 times the average film thickness of the lower side surface. It is desirable to be.

  As for the bottom of the pan, it is important not to make the heat insulating layer thick because the temperature cannot be sufficiently detected by the temperature sensor of the electromagnetic induction heating cooker.

  Moreover, regarding the flange part of a pan, whether to provide heat insulation is completely arbitrary.

  According to this configuration, the thickness of the heat-insulating layer gradually increases from the bottom of the cooking pan to the upper side of the cooking pan. By confining the heat stored in the upper part, the heat is evenly transmitted to the cooked food and the taste can be improved.

  On the contrary, the heat insulation layer becomes thinner toward the lower side and bottom of the side, but these parts are the part where the magnetic metal layer of the cooking pan generates heat and the surrounding part facing the electromagnetic induction coil arranged inside the main body. Since a heat insulation layer is provided on the surface of this part, heat is returned to the heat insulation layer, and the uniform heating is hindered. It is to make.

  The fifth invention is based on a multilayer metal, and the surface area of the outermost magnetic metal layer is increased by 1.05 to 2.0 times that of the untreated surface by roughening the surface of the magnetic metal layer. The resistance is increased.

  The surface of the magnetic metal is increased by roughening by blasting, but this increases the electrical resistance of the surface of the magnetic metal, thereby improving the heat generation of the magnetic metal layer. .

  If the increase in surface area is less than 1.05 times, there is no particular effect on the heat build-up, and if it is greater than 2.0 times, the surface of the magnetic metal becomes too rough, and the heat insulating coating and protection provided on the surface. Since the film causes surface roughness, it is desirable that the range be 1.05 to 2.0 times.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

  1 and 2, the electromagnetic induction cooker body 1 is provided with an electromagnetic induction coil 2 in the interior thereof and configured to cause the cooking pot 3 to generate electromagnetic induction heat, and further includes a cooking pot bottom temperature detection sensor 4. The temperature of the cooking pan can be detected.

  Here, the cooking pan 3 is made of a clad material in which a ferritic stainless steel having a thickness of 0.5 mm is used as a magnetic metal layer 5 and an aluminum 6 having a thickness of 1.0 mm is joined thereto. The layer 5 is made into a pan shape by pressing it with the outer surface as the outer surface.

  The surface of the aluminum 6 on the inner surface of the cooking pan 3 is treated with a two-layer fluororesin coat 7.

  After the base material is press-molded into a cooking pan shape and washed, sandblasting is applied to the inner surface of the aluminum 6, and the surface roughness Ra is adjusted to 3 to 5 μm. Thereafter, the fluororesin, the adhesive component, the pigment, A liquid primer coating containing a glittering material as a coating film component was applied to a film thickness of about 10 μm after film formation, and dried at 100 ° C. for 20 minutes.

  When the drying of the primer is completed and the substrate temperature is sufficiently lowered, a film coating of fluororesin powder containing no additives such as pigments and glittering materials as a top coat treatment is formed on the primer to a film thickness of 35 μm. Painted as follows.

  On the other hand, on the outer surface of the magnetic metal layer 5 constituting the outer layer of the cooking pot base material, the surface roughness Ra is adjusted to 0.5 to 3 μm by sandblasting to form the roughened surface 8, and thereafter The surface of the roughened surface was sprayed so that the nickel / chromium alloy had a thickness of about 50 μm.

  The purpose of the nickel / chromium alloy layer 9 is to alleviate the difference in thermal expansion coefficient between the stainless steel substrate and the upper ceramic layer, and prevent the ceramic layer from peeling off from the substrate. Considering the thermal load, it is necessary to consider the necessity.

  Further, alumina, which is a kind of ceramic, was thermally sprayed as a heat insulating layer 10 on the nickel / chromium alloy sprayed layer 9. This heat insulating layer 10 made of alumina was coated so as to have an average film thickness of 100 to 200 μm at the pan bottom surface 3a, 400 to 600 μm at the upper side surface 3b, and 200 to 300 μm at the lower side surface 3c.

  Since this thermal insulation layer 10 made of sprayed alumina contains voids, its thermal conductivity is lower than that of alumina not containing ordinary voids, and its thermal conductivity is 2.36 W / m · k.

After spraying the alumina layer, it is desirable to provide a heat-resistant coating 11 such as silicone, epoxy, or polyethersulfone on the upper layer with a thickness of about 20 μm. The purpose is to smooth the surface of the layer 10 because it is somewhat rough, and to seal the pores present in the heat insulating layer 10 and improve the corrosion resistance.

  It is possible to add phenol carbide particles, glass particles, ceramic particles such as silicon carbide and alumina, diamond particles, and the like as additives to the heat-resistant coating material 11 and have high Mohs hardness and withstand high temperatures during cooking. The wear resistance can be improved by adding an additive having high stability to various chemicals.

  Here, as a comparative example 1, a pan having the same shape as the cooking pan of the present embodiment and having the same thickness aluminum and ferritic stainless steel as a base material, and the outer surface of which is not subjected to any treatment, A comparative experiment with the pan in the present embodiment was performed.

  When 1 L of water was placed in the pan of this embodiment and the pan of Comparative Example 1 and placed on an electromagnetic induction heating cooker and operated at 100 V, the generated power was improved by about 5% as shown in (Table 1). This is an effect obtained as a result of the increase in the area receiving the magnetic force and the change in the electrical resistance of the surface of the magnetic metal layer due to the roughening treatment applied to the outer surface of the pan of the present embodiment.

  Since the heat generation amount of the magnetic metal surface layer is larger as a characteristic of electromagnetic induction heat generation, efficient heat generation can be realized by roughening the surface layer and increasing the current flowing area, As a result of adding the heat insulating effect of the alumina layer as the layer 10, it was possible to boil water earlier.

  Next, the film thickness constitution of the heat insulating layer in the present embodiment was changed to the pan No. of (Table 2). When cooking with the cooking pot changed like 1-8, the taste result compared with the comparative example 1 is similarly shown in (Table 2).

  In Table 2, the cooking pot for 5.5 go rice cooking is put on the electromagnetic induction heating cooker body, and the result of rice when 3 go rice is cooked normally is shown. In the taste determination, ◎ means that the taste is significantly improved over the standard, ○ means that the taste is improved over the standard, Δ means a taste at the same level as the standard, and x means below the standard.

  The taste is determined by comprehensively judging the taste, aroma, stickiness, hardness, bulging degree, etc. of the cooked rice.

  As shown in Table 2, as compared with the present embodiment, in the case where the film thickness or the balance of the film thickness is changed, the taste better than the standard is not obtained in any case.

  From the above results, it is clear that in order to obtain a good taste, it is necessary to make the heat insulating film with low thermal conductivity an appropriate thickness depending on the part of the pan, and in order to obtain a good taste, the thermal conductivity The film thickness of the heat-insulating film containing the filler that lowers the thickness of the cooking pan is relatively thin at the bottom of the cooking pan and increases as it becomes the top of the cooking pan. Although it is important that the film thickness is twice or more as compared with the film thickness of the lower part 3c, the film thickness of the upper part of the side surface should not exceed 600 μm at the maximum.

(Embodiment 2)
FIG. 3 shows a case where the heat insulating layer is a ceramic coat 12, and is characterized by adding a filler 13 that lowers the thermal conductivity.

More specifically, the ceramic coat 12 includes a filler 13 that reduces the thermal conductivity, such as hollow glass beads or porous carbon particles, and is characterized by being thickened.

  In the case of hollow glass beads, a magnetic metal having a roughened ceramic coating layer containing 10 to 50% by weight of a coating having an average particle size of 10 to 80 μm and a specific gravity of 0.05 to 0.5 g / ml It is desirable to provide 100 μm or more on the surface, and it is desirable to increase the thickness as it becomes the upper part of the pan.

  If the hollow glass beads are less than 10% by weight, the performance of sufficiently confining heat in the pan will not be exhibited, and if it exceeds 50% by weight, the coating film is brittle and does not function as a film, so 10 to 50% by weight is desirable. .

  Further, a protective coating layer 14 can be provided as a second layer on the ceramic coating 12, but the filler 15 for reducing the thermal conductivity such as hollow glass beads added to the protective coating layer 14 is It is desirable to make it 10% by weight or less.

  This is because the purpose of improving the strength and protecting the ceramic coat 12 of the first layer from abrasion and impact is higher than the purpose of lowering the thermal conductivity in the upper layer part than the second layer.

  According to this configuration, since the surface of the magnetic metal is roughened, the surface characteristics of the magnetic metal are changed. As a result, the heat generation property of the magnetic metal layer is improved and the surface of the roughened surface is improved. Since the heat-resistant heat-insulating film having a lower thermal conductivity than the material is provided, it is difficult for the heat generated in the magnetic metal layer to escape to the outside, and the cooking result can be positively affected.

  For the purpose of improving the adhesion between the ceramic coating to which the filler for reducing the thermal conductivity is added and the base material, a thin primer layer may be provided between the roughened surface of the magnetic metal layer.

  Furthermore, when a large amount of filler, such as hollow glass beads, is added to the ceramic coating layer to reduce the thermal conductivity, the resin component in the coating is relatively reduced, protecting the ceramic coating layer from wear and impact. Therefore, securing the strength is a big problem.

  For this reason, by adding fine particles such as carbide particles, ceramic particles, glass particles, and diamond particles to the ceramic coating layer and its protective coating layer, the wear resistance is improved, and it becomes strong against indentation scratches and the like.

  As described above, the cooking pan for an electromagnetic induction cooker according to the present invention is subjected to a surface roughening treatment on the surface of the magnetic metal layer constituting the outer layer of the cooking pan base material, and a highly heat-insulating film is applied to the roughened surface. Since it is processed, efficient heat generation is possible, cooking performance is improved, and it has high durability, so it is useful for various electromagnetic induction cooking.

Sectional drawing of the cooking pot in Embodiment 1 of this invention The partial expanded sectional view of the cooking pan in Embodiment 1 of this invention Partial expanded sectional view of the cooking pan in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Cooking pan 3b Upper part of side surface 3c Lower part of side surface 5 Magnetic metal layer 8 Roughening surface 10 Heat insulation layer 12 Ceramics coating 13 Filler

Claims (5)

A cooking pot for an electromagnetic induction cooker in which a surface of a magnetic metal layer is subjected to a roughening treatment, and a heat insulating layer having a thermal conductivity of 1/5 or less of a magnetic metal material is disposed on the outer surface thereof. The cooking pot for an electromagnetic induction cooker according to claim 1, wherein the heat insulating layer is ceramics. 2. The cooking pot for an electromagnetic induction cooker according to claim 1, wherein the heat insulating layer is a ceramic coat, and a filler that reduces thermal conductivity is added. The cooking pot for an electromagnetic induction cooker according to any one of claims 1 to 3, wherein the heat insulating layer has a thickness that is increased toward an upper portion. The surface area of the outermost magnetic metal layer was increased by 1.05 to 2.0 times that of the untreated surface by using a multilayer metal as a base material, and the electrical resistance of the surface portion was increased. The cooking pot of the electromagnetic induction cooker according to any one of claims 1 to 4, wherein the cooking pot is an electromagnetic induction cooker.

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