WO2003091630A1

WO2003091630A1 - Heating cooking utensil and method for manufacture thereof, and method for use thereof

Info

Publication number: WO2003091630A1
Application number: PCT/JP2003/005348
Authority: WO
Inventors: Yoshiyuki Nakanishi
Original assignee: Toto Ltd.
Priority date: 2002-04-25
Filing date: 2003-04-25
Publication date: 2003-11-06
Also published as: JP2005321108A; AU2003235138A1

Abstract

A method for manufacturing a heating cooking utensil, characterized in that a surface layer is formed by a method comprising a step of applying an aqueous coating fluid containing water and a water-soluble zirconium compound or a water-dispersible zirconium oxide sol having an average particle diameter of 50 nm or less on the surface of at least the portion comprising a heat-resistant base material of the heating cooking utensil, and a step of firing the resultant surface. The method can be used for manufacturing, at a low cost and with safety, a heating cooking utensil which exhibits excellent durability even in the use in a place which is frequently exposed to a high temperature and also to water, a salt and the like, such as one around a kitchen range or in a grill, and allows a scorched material adhered to the surface thereof to be easily removed only by immersion into water and then light rubbing by a finger or a dishcloth.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to all cooking utensils used for heating cooking indoors and outdoors and methods of using the same. Background technology ''

Pots used in indoor kitchens and kitchens, frying pans, soup trays, burner rings, water plates for grills for grilling fish, windowpanes for grills inside, grills, and barbecues outdoors In the case of hot cooking utensils such as iron plates and grills, which are liable to burn, it was natural to use abrasives or the like to basically remove the burns on the brute force.

In addition, some kitchen top plates and other products were processed with fluororesin as a coating agent that is resistant to scorching.

In addition, for the purpose of suppressing the rise in the temperature of the stove and improving the productivity of cooking utensils, there have been cases where zirconium oxide is sprayed onto the outer peripheral surface of the cooking device using infrared rays.

Shaving off the attached charcoal with an abrasive, etc., as a result, places a burden on maintenance and accelerates the deterioration of the product itself, resulting in a shortened life.

In addition, when a fluororesin-processed product is used in areas such as around a stove or inside a grill where it is constantly exposed to high temperatures and water, salt, etc., high durability is required, and deterioration such as discoloration and deformation due to heat is required. It is difficult to use from the point of view.

In the past, as can be seen in Japanese Patent Application Laid-Open No. 8-187185, the outer peripheral surface of a heating cooker using infrared rays, that is, the surface that is not actually exposed to cooking, is used. There is a finding that a ceramic layer is formed by spraying zirconium oxide. Japanese Patent Application Laid-Open No. 8-187185 also mentions that burning after use is easy. However, in this technique by thermal spraying, voids are generated on the surface of the ceramic layer, and the compactness and smoothness are inevitably impaired, and there is no luster, which is a limit in terms of easy burning. There was.

In the past, there is a finding that a zirconium oxide film is formed by forming a coating film using a Zr alcoholate as seen in Japanese Patent Application Laid-Open No. 5-317179. However, in the technology using Zr alcoholate, since the raw material Zr alcoholate is expensive and has high reactivity with water, water cannot be used in the production process, and the organic solvent of the flammable material is not used. They had to be used and had the problem of high cost and fire risk. Zr alcoholate is converted to zirconium oxide through hydrolysis and polycondensation.However, the volume shrinkage at that time is large, so voids and cracks are liable to be formed in the produced zirconium oxide film, which is sufficient for removing scorch. It is difficult to obtain satisfactory performance. Furthermore, since the Zr alcoholate has a high hydrolysis rate, the surface of the coating film tends to be roughened if rapid hydrolysis occurs during film formation. In order to form a smooth and dense coating film, many measures are required and handling is not easy.

Therefore, the present invention provides a cooking method which has excellent durability in an environment where it is constantly exposed to water, salt and the like at high temperature, and which can be easily removed by immersing it in water and rubbing lightly with a finger or a cloth. It is an object of the present invention to provide an appliance, a method for manufacturing the cooking appliance at low cost and safely, and a method for using the cooking appliance. Disclosure of the invention

In order to solve the above-mentioned problems, in the present invention, a step of applying a water-based coating solution containing a water-soluble zirconium compound and water to at least the surface of a portion composed of a heat-resistant substrate of a cooking device, Thereafter, a firing step is provided. To form a surface layer.

In another embodiment of the present invention, a water-dispersible zirconium oxide sol having an average particle diameter of 50 nm or less and water is provided on at least the surface of the portion of the cooking device constituted by the heat-resistant base material. A step of applying a water-based coating solution containing: and thereafter, a step of baking to form a surface layer.

According to the present invention, since a smooth and strong surface layer containing zirconium oxide is formed on the surface, if the dirt attached during cooking is heated and scorched, this cooking device is suitable for water or hot water. If soaked for a long period of time, it is possible to provide a cooker that can remove the scorch by rubbing lightly with a finger or a cloth. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view schematically showing a cooking device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a method of using the cooking device of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a cooking device according to an embodiment of the present invention _(in FIG. 1, a water-soluble zirconium compound or an oxidized After applying an aqueous coating solution containing zirconium sol and water, the surface layer 2 is formed by firing.

(1) Cooking utensils

Examples of cooking utensils include ovens used in indoor kitchens and kitchens, microwave ovens, cookers, pans, frying pans, grills for grilling fish, and iron plates and grills used outdoors for barbecues. Can be

In particular, the parts of these cooking utensils that are prone to burning due to the adhesion of foods and juices, such as the inner walls of cooking rooms such as ovens and microwave ovens, viewing windows, pans, etc. Pans, pans, handles, etc. , Grilled water for grilling fish, grill net, window for grilling, etc.

The heat-resistant base material in the present invention refers to a material that constitutes the above-mentioned cooking device and can withstand an overheating load, such as a steel plate porcelain, a porcelain porcelain enamel, a glazed ceramic, and a heat-resistant glass. For example, those having a vitreous surface can be suitably used. Further, as the heat-resistant base material of the present invention, a metal such as a steel sheet, a solid, a stainless steel, or a glass coated with a heat-resistant coating can be suitably used. Here, the heat-resistant coating refers to a coating whose main component contains a silicone resin or a fluororesin, and whose coating has a heat-resistant temperature of about 400 ° C. or higher.

(2) Aqueous coating liquid

The aqueous coating solution used to form the surface layer contains a water-soluble zirconium compound or a water-dispersible zirconium oxide sol, and water.

In the present invention, as the water-soluble zirconium compound, zirconyl nitrate, zirconyl acetate, zirconium ammonium carbonate, zirconium complex, or the like can be used alone or in combination. Examples of zirconium complexes include; dicarponyl compounds such as 8-diketones, organic acids such as citric acid, malic acid, and succinic acid; compounds such as amines, pyridines, and pyrroles; and complexes and derivatives thereof with zirconium. Ammonium salt and the like.

The water-dispersible zirconium oxide sol of the present invention is a sol in which zirconium oxide is dispersed in water and Z or a water-soluble organic solvent, and a sol that can be diluted with water can be used. In the zirconium oxide sol, those having an average particle diameter of 5 Onm or less, preferably 10 nm or less, more preferably 2 nm or less are used. Zirconium oxide sol having a particle diameter of more than 50 nm is not suitable because of poor smoothness, denseness and film forming property.

Here, the method of measuring the average particle diameter is divided into the following two types depending on the size of the target particle diameter. When the average particle diameter is 10 nm or more, the average particle diameter is measured by a laser-diffraction method, and when the average particle diameter is 10 nm or less, it is measured by a laser-Doppler light scattering / heterodyne method. In the aqueous coating solution of the present invention, at least one of the above-mentioned water-soluble zirconium compounds and zirconium oxide sol can be used. The water-soluble zirconia compound and zirconium oxide sol may be mixed and dispersed in water.

Zirconium oxide (Z r 0 ₂₎ in terms of content level in the aqueous coating solution of the present invention is 0. 1% by weight or more and less than 5 wt%.

If the content is less than 0.1% by weight, the compactness of the surface layer may be reduced and the effect may be weakened. If the content is more than 5% by weight, the surface layer is too thick, causing coating unevenness and the like, and the molding itself is difficult. Is not preferred.

In aqueous coating solution of the present invention, and more preferably zirconium oxide (Z R_〇 ₂₎ conversion calculation containing concentrations, '0.5 wt% or more and 3 wt% or less, more preferably 1 wt% or more, 3 weight % Or less.

As other components of the aqueous coating solution used for forming the surface layer, a binder, a wettability adjuster, a PH adjuster, and the like can be added. These components are not essential, _c binder can contribute to the improvement of stability improvement and the aqueous coating liquid of the coating properties, water glass, i.e., sodium Kei, potassium Kei acid, Ke I acid Alkali silicates such as lithium and ammonium silicate can be used. The amount of the alkali carbonate added is 100 parts by weight or less based on 100 parts by weight of zirconium oxide in terms of silica (Si ₂ ). If the amount exceeds 100 parts by weight, the charred salt is strongly adhered to the alkali silicate, which is not preferable. Conventional binders bind substances from one substance to another, so if they are present in large quantities, the same effect will occur for charring. By setting the amount to be 100 parts by weight or less, it is possible to easily form a surface layer without impairing the effect of zirconium oxide.

Surfactants and water-soluble organic solvents can be used as the wetting agent.

The type of surfactant is not particularly limited, and anionic, cationic, and nonionic surfactants can be used. The surfactant is appropriately selected according to the pH of the aqueous coating solution and the dispersibility of zirconium oxide. The amount of surfactant added depends on the wetting of the aqueous coating solution. It is sufficient if there is a minimum amount required to improve the properties, but as a rough guide, it is preferably about 0.1 to 10% by weight based on the aqueous coating solution.

Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, and propanol, ethers such as tetrahydrofuran, methoxypropanol, ethoxyethoxypropanol, and esters such as hydroxyethyl acetate. It is about 0.5 to 50% by weight of the liquid, preferably about 1 to 20% by weight.

(3) Formation of surface layer

Next, a method for forming the surface layer will be described.

If necessary, the surface to which the aqueous coating liquid is to be applied is pretreated to such an extent that the aqueous coating liquid is uniformly wetted. Pretreatment methods include cleaning and degreasing with cleaning agents, abrasives, water, solvents, etc., corona discharge treatment, plasma treatment, under oxygen atmosphere,

A method of removing adhered dirt by baking at a temperature of about 500 or higher at 500 or more can be used.

Following the pretreatment, the aqueous coating solution is applied.

Well-known coating methods such as curtain coating, spray coating, flow coating, roll coating, and dip coating can be used.

Irregularities on the surface of the surface layer may cause scorching, so it is desirable to apply the coating as smoothly as possible during application. for that purpose,

(1) Before coating, the surface to which the aqueous coating solution is to be applied is heated in advance to ensure a surface temperature of 70 to 110 ° C, preferably 80 to 100 ° C, during coating ( Preheating),

Or,

② Coat several times with low concentration coating solution,

It is necessary to take measures such as to prevent coating unevenness. Next, baking is performed after the application of the aqueous coating solution. There are two main purposes of calcination: removal of solvent, physisorbed water, and soluble salts, and formation of zirconium oxide film. is there. It is desirable and advantageous to treat the film at as high a temperature as possible, with the upper limit of the heat resistant temperature of the surface to which the aqueous coating liquid is applied, in terms of the densification and strength of the film. As a specific example, it is desirable to perform the treatment at a firing temperature of 100 ° C. or higher, preferably 150 ° C. or higher. The melting point of zirconium oxide is 270 ° C, but the melting temperature of the porcelain is about 500 ° C, and the glazed layer of ceramics begins to melt at 800 ° C. Desirably less than the softening point of quality. The holding time of the firing temperature is about 10 seconds to 30 minutes.

(4) Surface layer

The surface layer formed by the above-described method has an arithmetic average roughness (Ra) specified in JIS B0601 of not less than 0.1 m and less than 0.5 m. By setting the content within the above range, it is possible to prevent the anchoring effect in which the burning is physically fixed to the unevenness of the surface layer.

A more preferable value of the average roughness is 0.1111 or more and less than 0.4 zm, particularly preferably 0.12 mm or more and 0.36 m or less.

For a more specific measurement of the arithmetic average roughness (R a), for example, a surface roughness profile measuring machine manufactured by Tokyo Seimitsu Co., Ltd., Surfcom 57 OA is used. Arbitrarily select three places from the sample surface, measure the arithmetic average roughness (Ra) described in JIS B0601 at a measurement distance of 1 mm, and calculate the average value.

The supported amount of zirconium oxide contained in the surface layer formed by the above method is 0.04 gZm ² or more and less than 2.3 g / m ² . By setting the content within the above range, it becomes possible to form a surface layer excellent in smoothness, denseness, and film forming property.

A more preferable range of the amount of the supported zirconium oxide is 0.04 gZm ² or more and 1.4 gZm ² or less.

The surface layer formed by the above method mainly contains zirconium oxide. The content of zirconium oxide is 40% by weight or more, preferably 50% by weight or more and 100% by weight or less of the surface layer. By setting the content within the above range, it is possible to easily remove the burn as described later. (5) How to use cooking utensils

FIG. 2 is a schematic view showing a method of using the cooking device of the present invention.

When dirt attached during cooking is heated and burnt 3 adheres to the cooking device of the present invention, the cookware is immersed in water or hot water 4 to remove burnt easily thereafter. It will be easier. More specifically, it can be removed by lightly rubbing with a finger or a cloth.

In the surface layer of the present invention, the interface between the surface and the charred surface is very inert, probably due to the presence of a large amount of zirconium oxide, which has a very small amount of equilibrium adsorption of the 〇H group, and is immersed. Accordingly, the adhesive force is gradually weakened and the charred surface rises, so that the charred surface can be easily removed thereafter.

If the scorch is weak, it is removed naturally, and even if it is relatively firm, it can be easily removed by rubbing it lightly with a sponge. Immersion in water or hot water should take at least 1 hour, preferably at least 3 hours.

Example 1

Bicarbonate Jill Conil ammonium Niu arm (first Kigenso Kagaku Co., Zr0 ₂ in terms of content concentration of 13 wt% stock solution) was adjusted with distilled water to Zr0 ₂ in terms of content level 1% by weight, water soluble coating solution # 1 I got Aqueous coating solution # 1 was applied by spraying to a coating of 45gZm ^{2 on} a steel plate (one coated with a common underglaze or dull coat) for heating and cooking. Then, baking was performed at a maximum baking zone temperature of 450 ° C. for 30 minutes using a roller hearth kiln to obtain a sample of Example 1. The arithmetic average roughness (Ra) of the sample was 0.16 / m. Arithmetic mean roughness (Ra) was measured using Surfcom 570A, a surface roughness profile measuring machine from Tokyo Seimitsu. Arbitrary three points were selected from the sample surface, and the arithmetic average roughness (Ra) described in JISB0601 was measured at a measurement distance of lmm, respectively, and the average value was calculated. In the following description, the arithmetic mean roughness (R a) was measured and calculated by this method.

Example 2

Nitrate zirconyl (first Kigenso chemical stocks made, Zr0 ₂ in terms of content level 25-fold stock solution Adjust the amount%) in distilled water Zr0 ₂ in terms of content level 1% by weight to obtain an aqueous coating † night # 2. Aqueous coating liquid # 2 was applied by spraying to a hollow steel plate for heating and cooking at a coating amount of 45 g / m ² . Then, baking was carried out at a maximum baking zone temperature of 450 ° C. for 30 minutes using a roller hearth kiln to obtain a sample of Example 2. The arithmetic average roughness (Ra) of the sample was 0.12 m.

Example 3

Zirconyl acetate (first Kigenso Kagaku Co., Zr0 ₂ in terms of content concentration of 15 wt% stock solution) was adjusted with distilled water to Zr0 ₂ terms containing 1 wt% concentration to give an aqueous coating solution # 3. Aqueous coating solution # 3 was coated on the enameled steel plate for cooking by spraying at a coating amount of 45 gZm ² . Then, the sample was fired at a maximum sintering zone temperature of 450 with a roller and hearth kiln for 30 minutes to obtain a sample of Example 3. The arithmetic mean roughness (Ra) of the sample was 0.16 m.

Example 4

Aqueous coating solution # 1 was coated on a steel plate for heating and cooking with a spray at a coating amount of 45 gZm ² . Then, the sample was fired at a maximum firing zone temperature of 150 ° C. for 30 minutes using a roller and hearth kiln to obtain a sample of Example 4. The arithmetic average roughness (Ra) of the sample was 0.16 m.

Example 5

The aqueous coating solution # 2 in E bite one steel plate for cooking, it was co one coating at SPRAY under the conditions of coating amount 45GZm ^2. Then, the sample was fired in a roller hearth kiln at a maximum firing zone temperature of 150 ° C for 30 minutes to obtain a sample of Example 5. The arithmetic average roughness (Ra) of the sample was 0.16 m. '

Example 6

Aqueous coating solution # 3 was coated on an enameled steel plate for cooking by spraying under the conditions of a coating amount of 45 gZm ² . Then, the sample was fired at a maximum firing zone temperature of 150 ° C. for 30 minutes using a roller and hearth kiln to obtain a sample of Example 6. The arithmetic average roughness (R a) of the sample was 0.20 nm. Example 7

Zirconium complex (manufactured by Teikoku Chemical Co. Eorido Z- 66 1 B, Zr0 ₂ in terms of content concentration of 4% by weight of the stock solution) was adjusted with distilled water to Zr0 ₂ in terms of content level 1% by weight, the water coating solution # 7 Obtained. Aqueous coating solution # 7 was coated on an enameled steel plate for cooking by spraying under the conditions of a coating amount of 45 g / m ² . Then, the sample was fired for 30 minutes at the maximum firing zone temperature of 450 ° C in a mouth-rhersharing to obtain a sample. The arithmetic average roughness (Ra) of the sample was 0.20 m.

Example 8

Zirconium oxide sol having an average particle diameter of 2 nm (Taki Chemical Co., Zr0 ₂ in terms of free organic concentration of 5 wt% stock solution) was adjusted with distilled water to Zr0 ₂ in terms of content level 1% by weight, the aqueous coating solution # 8 Obtained. Aqueous coating solution # 8 was spray-coated on a steel plate of a hood for heating and heating at 80 ° C in advance with a coating amount of 45 gZm ² . The sample was fired at 450 ° C. for 30 minutes at a maximum firing zone temperature in a mouth laher kiln to obtain a sample of Example 8.

The particle size was measured by laser Doppler light scattering / heterodyne method using MI CROTRAC UP A of Nikkiso Co., Ltd. The arithmetic mean roughness (Ra) of the sample was 0.16 m.

Example 9

The average particle diameter of 10nm was adjusted to Zr0 ₂ terms containing 1 wt% concentration with distilled water zirconium oxide sol (primary Kigenso Kagaku Co., Zr0 ₂ in terms of content concentration of 10 wt% stock solution), an aqueous coating solution # 9 I got Aqueous coating liquid # 9 was sprayed onto a steel plate for heating and cooking heated to 80 ° C in advance at a coating amount of 45 gZm ² . Then, sintering was performed at a maximum sintering zone temperature of 450 ° C. for 30 minutes using a roller hearth kiln to obtain a sample of Example 9. The particle size was measured using a laser Doppler light scattering 'heterodyne method' using MIC ROT RACUP A from Nikkiso Co., Ltd. The arithmetic mean roughness (Ra) of the sample was 0.20 m.

Example 10 The average particle diameter of 50nm was adjusted to Zr0 ₂ terms containing 1 wt% concentration with distilled water zirconium oxide sol (Nissan Chemical Industries, Ltd., Zr0 ₂ in terms of content concentration of 30 wt% stock solution), water soluble coating solution # 1 0 I got An aqueous coating liquid # 10 was coated by spraying on a hollow steel sheet for heating and heating at 80 ° C. in advance at a coating amount of 45 g / m ² . The sample was fired at a maximum firing zone temperature of 450 ° C. for 30 minutes using a roller hearth kiln to obtain a sample of Example 10. The particle size was measured by a laser diffraction method using MI CROTRA C FRA manufactured by Nikkiso Co., Ltd. The arithmetic mean roughness (Ra) of the sample was 0.36 m.

Example 1 1

The average particle diameter of 50nm zirconium oxide sol and water glass material (Nissan Chemical Industries, Ltd., Zr0 ₂ in terms of content concentration of 30 wt% stock solution) (Nippon Kagaku silicate lithium 3 5, Si0 ₂ in terms of concentration of the raw solution 20 the weight%), respectively Zr0 ₂ terms containing 1 wt% concentration with distilled water, 1 Si0 ₂ in terms of content concentration was adjusted to 1 wt%: 1 aqueous coating coating solution # 1 1 were mixed at a weight ratio Obtained. The steel plate for heating and cooking was heated to 100 ° C. in advance, and the aqueous coating solution # 11 was coated by spraying under the conditions of a coating amount of 45 gZm ² . Then, the sample was fired in a roller hearth kiln at a maximum firing zone temperature of 450 ° C for 30 minutes to obtain a sample of Example 11. The particle size was measured by a laser diffraction method using MI CROTRA CF RA manufactured by Nikkiso Co., Ltd. The arithmetic average roughness (Ra) of the sample was 0.32 zm.

Example 1 2

Nitrate zirconyl (first Kigenso chemical stocks made, Zr0 ₂ in terms of content concentration of 25 by weight% stock solution) was adjusted with distilled water to Zr0 ₂ in terms of content concentration of 3% by weight to obtain an aqueous coating solution # 1 2. Aqueous coating solution # 12 was coated on a steel plate for heating and cooking with a spray at a coating amount of 45 g / m ² . Then, the sample was fired at a maximum firing zone temperature of 450 in a roller hearth kiln for 30 minutes to obtain a sample of Example 12. The arithmetic mean roughness (Ra) of the sample was 0.16 m. The viewing window glass inside the grill was heated to 70 ° C. in advance, and the aqueous coating solution # 2 was coated by spraying at a coating amount of 45 g / m ² . Then, baking was performed for 30 minutes at a maximum baking zone temperature of 450 ° C. in a mouth to hearth kiln, and a sample of Example 13 was obtained. The arithmetic average roughness (Ra) of the sample was 0.20 tm.

Example 14

The viewing window glass inside the grill was heated to 70 in advance, and the heat-resistant coating portion of the window glass was spray-coated with the aqueous coating solution # 2 at a coating amount of 45 g / m ² . Then, the sample was fired at a maximum firing zone temperature of 450 in a roller hearth kiln for 30 minutes. The arithmetic mean roughness (Ra) of the sample was 0.20 m.

Example 15

The hollow steel sheet for heating and cooking was heated at 110 ° C. in advance, and the aqueous coating solution # 2 was spray-coated at a coating amount of 45 g / m ² . Then, the sample was baked for 10 seconds using a mesh burner to obtain a sample of Example 15. The mesh surface temperature of Mesh Pana was set at 850. The maximum surface temperature of Hoguchi-Steel was 400 ° C. The arithmetic mean roughness (Ra) of the sample was 0.24 m. Example 16

Nitrate zirconyl (first Kigenso chemical stocks made, Zr0 ₂ in terms of content concentration of 25 by weight% stock solution) was adjusted with distilled water to Zr0 ₂ in terms of content level 0.1% by weight to obtain an aqueous coating solution # 1 6 . The hollow steel sheet for heating and cooking was heated to 110 ° C. in advance, and the aqueous coating solution # 16 was coated with a spray at a coating amount of 100 g / m ² . Then, sintering was performed for 30 minutes at a maximum sintering zone temperature of 450 ° C using a roller eight-skillen.

Six samples were obtained. The arithmetic average roughness (Ra) of the sample was 0.16 m. Comparative Example 1

Hollow steel plate for cooking. The arithmetic average roughness (Ra) was 0.202 m. Comparative Example 2

Zirconium oxide sol with an average particle size of 80 nm (produced by Daiichi Rare Element Chemical Co., Ltd. Adjust the Zr0 ₂ in terms of content concentration of 20 wt%) of a liquid with distilled water Zr0 ₂ in terms of content level 1% by weight to obtain an aqueous coating solution # 22. The aqueous coating solution # 22 was spray-coated on a hollow steel plate for heating and heating to 100 in advance under the condition of a coating amount of 45 gZm ² . Then, the sample was fired at a maximum firing zone temperature of 450 ° C. for 30 minutes using a roller and a hearth kiln to obtain a sample of Comparative Example 2. The particle size was measured by a laser diffraction method using MI CROTR AC FRA manufactured by Nikkiso Co., Ltd. The arithmetic mean roughness (Ra) of the sample was 0.56 / m.

Comparative Example 3

The average particle diameter of 80nm zirconium oxide sol (primary Kigenso Kagaku Co., Zr0 ₂ in terms of content concentration of 20 wt% of the original solution) and water glass material (Nippon Kagaku Keisan lithium 3 5, Si0 stock solution ₂ the terms containing a concentration of 20 wt%), respectively Zr0 ₂ terms containing concentration 1 wt% with distilled water, 1 Si0 ₂ in terms of content concentration was adjusted to 1 wt%: engaged mixed with 1 (by weight), aqueous Coating solution # 23 was obtained. Aqueous coating solution # 23 was coated with a spray at a coating amount of 45 gZm ^{2 on} a single hot-rolled steel plate for heating at 100 ° C in advance. Then, the sample was fired at a maximum firing zone temperature of 450 ° C. for 30 minutes using a roller and hearth kiln to obtain a sample of Comparative Example 3. The particle size was measured by a laser diffraction method using MICROTRAC FRA manufactured by Nikkiso Co., Ltd. The arithmetic mean roughness (Ra) of the sample was 0.52 m.

Comparative Example 4

Adjust the ceramic powder zirconium oxide having an average particle diameter of 5 ^ m with distilled water to Zr0 ₂ in terms of content level 1% by weight to obtain an aqueous coating solution # 24. An aqueous coating solution # 24 was coated by spraying on an enameled steel plate for heating and heating to 100 ° C in advance at a coating amount of 45 g / m ² . The sample was fired at a maximum firing zone temperature of 450 ° C for 30 minutes using a roller hearth kiln to obtain a sample of Comparative Example 4. The particle size was measured by a laser diffraction method using MIC ROTRAC FRA manufactured by Nikkiso Co., Ltd. It was not possible to determine the arithmetic mean roughness (R a) of the sample because the film had detached. Comparative Example 5

The aqueous coating solution # 24 was coated by spraying on an enameled steel plate for heating and heating previously heated to 100 ° C. under the conditions of a coating amount of 45 gZm ² . Then, the sample was baked for 30 minutes at a maximum sintering zone temperature of 500 ° C. with a roller porch-skiln to obtain a sample of Comparative Example 5. 500 ° C is the limit of the heat-resistant temperature of the enamel plate, and further heat treatment was not possible. The particle size was measured by a laser diffraction method using MICROTRAC FRA manufactured by Nikkiso Co., Ltd. It was not possible to determine the arithmetic mean roughness (R _a ) of the sample because the film had detached.

Comparative Example 6

Water glass material (Nippon Kagaku silicate lithium 3 5, Si0 ₂ in terms of content concentration of 20 wt% stock solution) of Si0 ₂ in terms of content level with distilled water and adjusted to 1 wt%, to obtain an aqueous coating solution # 26 Was. The aqueous coating solution # 26 was spray-coated on a hot-rolled steel plate for heating, which was previously heated to 80, with a coating amount of 45 gZm ² . Then, the sample was fired at a maximum firing zone temperature of 450 ° C. for 30 minutes using a roller hearth kiln to obtain a sample of Comparative Example 6. The arithmetic mean roughness (Ra) of the sample was 0.16 ^ m. Comparative Example 7

Nitrate zirconyl (first Kigenso chemical stocks made, Zr0 ₂ in terms of content concentration of 25 by weight% stock solution) was adjusted with distilled water to Zr0 ₂ terms containing 5 wt% to obtain an aqueous coating solution # 2 7. Aqueous coating solution # 24 was coated on a steel plate for heating and cooking with a spray at a coating amount of 45 gZm ² . Then, the sample was fired at 450 ° C for 30 minutes in a roller hearth kiln at a maximum firing zone temperature to obtain a sample. It was not possible to determine the arithmetic average roughness (R a) of the sample because the film had detached.

Evaluation

The ingredients to be scorched were soy sauce, sugar, and beaten eggs mixed at a weight ratio of 1: 1: 1. 0.1 g of this mixture was applied to the surfaces of the examples and comparative examples in a circle having a diameter of about 1 cm at 10 places using a dropper, and heated in a dryer at 260 ° C. for 15 minutes to be completely scorched. . This test is generally performed with a stove, etc. This is a test method. Then, it was taken out of the dryer, allowed to cool naturally in a normal room, and then immersed in tap water at room temperature (about 20 ° C). This was taken out at regular intervals and the number of burns removed was measured. When burnt, the same test was repeated at the same place again, and the durability was also evaluated. Table 1 shows the evaluation results.

table 1

(Note in the table)

3 hours after immersion, the number of burns removed out of 10 was described in the table by simply tracing lightly or naturally with a finger. For example, 2/10 indicates that two out of ten were removed. In the example in which the zirconium oxide surface layer having high smoothness was formed, a high scorch removal property was obtained stably. On the surfaces containing no zirconium oxide described in Comparative Example 1 and Comparative Example 6, scorch could not be removed. Comparative Examples 2 and 3 each had a surface containing zirconium oxide, but the arithmetic average roughness (Ra) of the surface was high at 0.56 xm and 0.52 m, respectively, and the surface was scorched. Removability Could not be sustained stably. These results indicate that a surface that contains mainly zirconium oxide and has an arithmetic average roughness (R a) of less than 0.5 m is required to stably maintain the removability of scorch. all right.

In addition, according to the production method of the present invention, as shown in Examples 4, 5, 6 and 15, the burnt removability can be stably maintained even at a relatively low temperature for a short period of time. It is possible to form a surface layer. Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, while having excellent durability also in the use around the stove or the inside of a grill etc. which are constantly exposed to high temperature, water, salt, etc., after being immersed in water, lightly scorch with a finger or cloth. It is possible to provide a method for inexpensively and safely manufacturing a cooking appliance that can be easily removed by rubbing, and a method for using the cooking appliance.

Claims

The scope of the claims

1. A step of applying an aqueous coating solution containing a water-soluble zirconium compound and water to at least the surface of a portion composed of a heat-resistant base material of a heating cooker, and thereafter, a step of firing. A method for producing a cooking appliance characterized by the above.

2. On the surface of at least the portion of the cooking utensil composed of the heat-resistant base material, apply an aqueous coating solution containing water and a water-dispersible zirconium oxide sol having an average particle size of 5 O nm or less and water. A method for manufacturing a heating cooker, comprising a step of applying and a step of baking thereafter.

3. On the surface of at least the portion of the cooking utensil composed of the heat-resistant base material, apply an aqueous coating solution containing water and a water-dispersible zirconium oxide sol having an average particle diameter of 1 O nm or less. A method for manufacturing a heating cooker, comprising a step of applying and a step of baking thereafter.

4. Apply an aqueous coating solution containing water and a water-dispersible zirconium oxide sol having an average particle diameter of 2 nm or less to at least the surface of the portion of the cooking utensil composed of the heat-resistant base material. A method for producing a heating cooker, comprising: a step; and a firing step thereafter.

5. A heating cooker comprising a surface layer formed by the production method according to claims 1 to 4.

6. The cooking device according to claim 5, wherein the arithmetic average roughness (Ra) of the surface layer is 0.5 or more and less than 0.5 ^ m.

7. The cooking device according to claim 5, wherein the amount of zirconium oxide carried on the surface layer is 0.04 gZm ² or more and less than 2.3 gZm ² .

8. If the dirt attached during cooking is heated and scorched on the cooking device according to any one of claims 5 to 7, the cooking device is immersed in water or hot water. The method of using cooking utensils, characterized by making it easier to remove burns afterwards.