Heating cooking container and method for manufacturing heating cooking container

Abstract

The present invention provides a heat cooking container which contains an object to be cooked therein and performs heat cooking using an electric heating unit, by modifying a part of a hard coating film which is formed on the inner surface and does not use fluorine, thereby providing a heat cooking container which is safe and durable, and which can be used for heat cooking using an electric heating unit. The heating cooking container and the manufacturing method of the heating cooking container can be realized at low cost. A heating cooking container (10) in which an object to be cooked is housed therein and cooked by being heated by an electric heating unit (14), the heating cooking container (10) having a hard coating film (13) formed on the inner surface thereof, the hard coating film comprising a sintered body of an inorganic substance, the hard coating film comprising: a non-transparent first layer (13a); and a translucent second layer (13b) laminated on the first layer, in which a predetermined portion of the first layer is modified to a different color from other portions, and the surface of the second layer as the modified portion is roughened.

Description

Technical Field

[0001] The present invention relates to a heating cooking container that contains food to be cooked and cooks it by electric heating, and to a heating cooking container having a hard coating formed on its inner surface, and a method for manufacturing the heating cooking container having the hard coating formed thereon. Background Art

[0002] As an example of a heating cooker that has become popular in recent years, there is an electric kettle that includes a main body that can be easily loaded and unloaded on a power supply stand. The electric kettle is a small electric kettle with a capacity of about 0.15 liters to 1.2 liters that meets the needs of users who want to quickly boil a small amount of hot water when using it. When water is placed in the heating cooking container, i.e., the water storage part in the main body and placed on the power supply stand, the power supply stand is used to energize the heater in the main body, and boiling hot water can be boiled in a short time of about 1 minute to 3 minutes. Most electric kettles do not have a heat preservation function like electric thermos kettles. In addition, when the hot water boils, only the main body can be lifted from the power supply stand, and the main body can be tilted in the same way as the existing kettle to inject hot water, and hot water can be injected into a coffee cup or the like from the spout.

[0003] In various heating cooking devices such as electric kettles and rice cookers that cook food by electric heating, a coating film is formed on the inner surface of a metal container body in a heating cooking container that contains food to prevent the food from sticking. As a coating film for such a heating cooking container, a fluorine coating that is not easy for food to stick to and can be formed relatively easily is the mainstream, but in recent years, due to concerns about the safety and environmental impact of fluorine compounds, hard films such as ceramics are often used instead of fluorine resin processing that has been used in the past.

[0004] Compared with coating films formed of fluororesins that peel off when strongly rubbed, coatings made of hard films such as ceramics have higher durability and can protect the inner surface of containers for a long time. On the other hand, since ceramic coatings have high non-adhesiveness, there is a problem that when forming water volume scale lines on the inner side surface of a container, it is difficult to form scale lines on the inner side surface of a container using conventional scale line forming methods such as printing or engraving.

[0005] In order to solve this problem, the following method has been proposed: two films of different colors are stacked as a ceramic coating, and holes in the form of a scale line pattern are formed in the surface film by laser processing, and the color of the film of the lower layer can be seen from the hole portion, thereby displaying the scale line indicating the amount of water (see Patent Document 1). In addition, as another method, a method has been proposed in which a surface portion of a ceramic coating film is cut by laser processing to form a groove-shaped portion, and a paint or ink is injected into the groove-shaped portion to form the water amount scale line (see Patent Document 2).

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2011-160871

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2012-005627 Summary of the invention

[0010] [Problems to be solved by the invention]

[0011] However, the scale line forming method described in Patent Document 1 has the following problems: since the top coating layer formed on the surface of the double-layer ceramic coating is removed, the coating film thickness of the scale line portion becomes thinner, making it difficult to ensure durability, and a step difference is formed at the boundary between the scale line portion and other portions, so the top coating film is easily peeled off. In addition, the technology described in Patent Document 2 has the following problems: in order to improve visual recognition, it is necessary to fill the groove-shaped portion formed in the ceramic coating with ink, etc., which increases the number of processes, thereby increasing the manufacturing cost, and further, depending on the ink material, the environmental load increases.

[0012] The present invention is an invention that solves the problems of the prior art. Its purpose is to provide a heating cooking container that has safety and durability and can be realized at low cost by modifying a portion of a hard coating that does not use fluorine formed on the inner surface of a heating cooking container that accommodates food to be cooked and heats it using an electric heating unit.

[0013] [Technical means to solve the problem]

[0014] In order to solve the above-mentioned problem, the heating cooking container of the present invention contains food to be cooked inside and uses an electric heating unit to heat and cook. The heating cooking container is characterized in that a hard coating film containing a sintered body of an inorganic substance is formed on the inner surface, and the hard coating film has: a non-transparent first layer; and a light-transmitting second layer, which is stacked on the first layer, a specified part of the first layer is modified to a color different from other parts, and the surface of the second layer as the modified part is roughened.

[0015] In addition, the manufacturing method of the heating cooking container of the present invention is a manufacturing method of the heating cooking container that accommodates the cooked food inside and cooks it by heating it with an electric heating unit, and is characterized by comprising: a coating formation step of forming a hard coating film containing a sintered body of an inorganic substance on the inner surface of the heating cooking container; and a laser processing step of irradiating an ultraviolet (UV) laser on the surface of the formed hard coating film to roughen the surface.

[0016] [Effects of the Invention]

[0017] The cooking container of the present invention has a hard coating film formed on its inner surface, which is a sintered body of an inorganic substance. The hard coating film has a non-transparent first layer and a light-transmitting second layer laminated on the first layer. A predetermined portion of the first layer is modified to a color different from other portions, and the surface of the second layer as the modified portion is roughened. Therefore, a scale line indicating the amount of the content of the contained cooking object can be formed by the modified portion of the first layer, and the scale line can be protected by the second layer covering the modified portion.

[0018] In addition, the manufacturing method of the heating cooking container of the present invention includes: a coating formation step of forming a hard coating including a sintered body of an inorganic substance on the inner surface of the heating cooking container; and a laser processing step of irradiating the surface of the formed hard coating with UV laser to roughen the surface. Therefore, the coating that is not easy to peel off and is environmentally friendly can be formed with UV laser without causing significant damage to the coating, and the scale lines indicating the capacity or the surface of the coating can be modified. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a perspective view showing the appearance of an electric kettle including a heating cooking container according to an embodiment of the present invention as a water storage portion.

[0020] Figure 2 It is a cross-sectional view showing the structure of an electric kettle including a heating cooking container according to an embodiment of the present invention as a water storage portion.

[0021] Figure 3 It is a partially enlarged cross-sectional view showing the structure near the bottom of the water storage part.

[0022] Figure 4 This is an image diagram showing a UV laser irradiation state when water level scale lines are formed on the inner side surface of the water storage portion of the electric kettle according to the present embodiment.

[0023] Figure 5 (a) to Figure 5 (c) is an image diagram for explaining the change of the beam spot based on the relationship between the focus position of the UV laser and the irradiation surface.

[0024] Figure 6 This is a diagram showing water volume scale lines formed on the side surface of the water storage portion by laser processing using a UV laser.

[0025] Figure 7 (a) Figure 7 (b) is a diagram showing changes in the concavo-convex shape of the bottom surface of the water storage portion caused by laser processing using a UV laser.

[0026] Figure 8 This is a diagram showing the wettability of the bottom surface of the water storage portion whose coating surface has been roughened by UV laser.

[0027] Fig. 9 (a) Fig. 9 (b) is a diagram for explaining the effect of temperature rise caused by the bottom surface roughened by UV laser.

[0028] Fig.10 The diagram explains the difference in damage to the ceramic coating caused by surface roughening using UV laser and surface roughening using mechanical polishing.

[0029] Fig.11 (a) Fig.11 (b) is a diagram for explaining an example of forming a roughened area on the bottom surface of the water storage portion.

[0030] Fig.12 It is a cross-sectional view showing the structure of a rice cooker including the heating cooking container according to the embodiment of the present invention as an inner pot.

[0031] [Explanation of Symbols]

[0032] 10: Water storage part (heating cooking container)

[0033] 12: Inner container

[0034] 13: Ceramic coating (film)

[0035] 13a: The first layer of ceramic coating (film)

[0036] 13b: Second layer of ceramic coating (film)

[0037] 14: Heater (electric heating unit)

[0038] 15: Temperature sensor DETAILED DESCRIPTION

[0039] The heating cooking container of the present invention accommodates food to be cooked inside and uses an electric heating unit to heat and cook. In the heating cooking container, a hard coating film containing a sintered body of an inorganic substance is formed on the inner surface, and the hard coating film has: a non-transparent first layer; and a light-transmitting second layer, which is stacked on the first layer, a specified part of the first layer is modified to a color different from other parts, and the surface of the second layer as the modified part is roughened.

[0040] The cooking container of the present invention includes the above structure, so that predetermined characters or patterns can be drawn on the hard coating film through the modified portion of the first layer, and the characters or patterns can be protected by the second layer.

[0041] In the heating cooking container, at least one of ceramics and glass can be preferably used as the inorganic substance.

[0042] In addition, the first layer is preferably formed of a material that changes color by photolysis, thereby allowing the desired characters or patterns to be formed without causing significant damage to the hard coating.

[0043] Furthermore, the modified portion is formed on the side surface of the heating cooking container, and a scale line indicating the storage amount of the content can be formed by the modified portion.

[0044] Furthermore, by forming the modified portion on the bottom surface of the cooking container, the roughened modified portion of the second layer can be made hydrophilic.

[0045] In this case, the modified portion is preferably a portion of the bottom surface facing a location where the electric heating unit is disposed and / or a portion facing a location where a temperature sensor for detecting the temperature of the cooking container is disposed.

[0046] In addition, the heating cooking container may be provided as a water storage portion of an electric kettle, or the heating cooking container may be provided as an inner pot of an electric rice cooker.

[0047] The manufacturing method of the heating cooking container of the present invention is a manufacturing method of the heating cooking container that contains the food to be cooked and cooks it by heating it with an electric heating unit, comprising: a coating formation step of forming a hard coating film containing a sintered body of an inorganic substance on the inner surface of the heating cooking container; and a laser processing step of irradiating a UV laser on the surface of the formed hard coating film to roughen the surface.

[0048] Thus, the method for producing a cooking container according to the present invention can make the roughened portion hydrophilic without causing significant damage to the hard coating.

[0049] In the coating film forming step, it is preferred to form a non-transparent first layer and a light-transmitting second layer stacked on the first layer. Thus, the non-transparent first layer can be modified while the transparent second layer remains, and text or a pattern can be formed.

[0050] By the laser processing step, the first layer on the side surface of the heating cooking container is modified to form scale lines indicating the storage amount of the food to be cooked stored in the heating cooking container.

[0051] Furthermore, it is preferred that at least one of a portion of the bottom surface of the cooking container facing the arrangement position of the electric heating unit and a portion facing the arrangement position of a temperature sensor for detecting the temperature of the cooking container is roughened by the laser processing step. Thus, the roughened portion becomes hydrophilic, which can effectively prevent the generation of large bubbles when the temperature is increased.

[0052] (Implementation Method)

[0053] Hereinafter, the heating cooking container of the present invention will be described by taking as an example a heating cooking container used as a water storage portion of an electric kettle.

[0054] In the electric kettle described in the present embodiment, the water storage part included in the main body has a hard coating formed of an inorganic sintered body, i.e., a ceramic coating, on the surface of the inner side of the metal inner container. The ceramic coating formed on the side of the water storage part has scale lines, i.e., water volume scale lines, indicating the amount of water stored as the storage amount of the storage object. In addition, the ceramic coating formed on the bottom surface of the water storage part is roughened by laser processing using a UV laser. In addition, in the electric kettle described in the present embodiment, the cover body that closes the opening of the main body includes a movable closing member, and the movable closing member is linked to a hot water supply switch that controls the opening and closing of the hot water supply path when hot water is injected from the pouring port, and further includes a structure to prevent hot water from overflowing from the steam path when it is overturned.

[0055] Figure 1 It is a perspective view showing the appearance of an electric kettle including the heating cooking container according to the present embodiment as a water storage portion.

[0056] The electric kettle includes a main body 1 , a handle 2 fixed to the outer shell of the main body 1 , and a cover 3 that can open and close the opening of the upper part of the main body 1 . The main body 1 can be detachably placed on a power supply stand 4 .

[0057] Figure 1 The electric kettle shown in the figure includes a spout portion 5 in the main body 1, the spout portion 5 is formed at the upper end of the side surface which is radially opposite to the handle 2 and is used to store water or hot water for boiling water in the water storage portion 10 in the main body 1 (see Figure 2 , Figure 3 ) into a coffee cup, etc.

[0058] in addition, Figure 1The electric kettle shown has a structure in which the lid 3 is inserted from above the main body 1 to close the opening of the main body 1, and the lid 3 is provided with: a mounting and dismounting lever 6 for releasing the spring mechanism for fixing the lid 3 to the main body 1; and a hot water supply switch 7 for opening the hot water supply passage from the inside of the main body 1 to the spout 5 when hot water stored in the inside of the main body 1 is poured. In addition, the electric kettle described in this embodiment has a structure in which the spout 5 for pouring the liquid in the water storage part 10 also serves as a steam discharge port for releasing steam, so the steam discharge port on the handle 2 side of the upper surface of the lid 3 is not formed. In addition, a protruding portion 8 that partially covers the upper surface of the spout 5 is formed at the end of the lid 3 on the spout 5 side.

[0059] The handle 2 is provided with a power switch 9 for starting to energize a heater as an electric heating unit, and the heater as the electric heating unit can heat and boil liquid such as water stored in the main body 1. The power switch 9 has a function of automatically stopping the energization of the heater to prevent dry boiling when it detects that the hot water in the main body 1 is boiling.

[0060] Figure 2 Viewed from the side of the straight line connecting the nozzle and the handle Figure 1 The cross-sectional view of the electric kettle shown. Figure 3 It is a partial enlarged cross-sectional view showing an enlarged portion near the bottom surface of the water storage unit.

[0061] like Figure 2 As shown in FIG. 1 , the main body 1 of the electric kettle is configured such that a water storage part 10 as a heating cooking vessel of this embodiment is arranged inside a resin outer casing 11. The water storage part 10 has a ceramic coating 13 formed on the inner surface of a metal inner container 12 made of stainless steel or the like, i.e., on the surface of the part that stores water. Figure 3 As shown, in the water storage unit 10 of the heating cooking container of this embodiment, the ceramic coating 13 formed on the inner surface of the inner container 12 is formed as a laminated film of a first layer 13a and a second layer 13b, wherein the first layer 13a is formed on the inner surface of the inner container 12 and the second layer 13b is laminated on the inner surface of the first layer 13a. Figure 3 As shown, below, the portion of the first layer 13a formed on the side of the water storage section 10 is referred to as 13a1, and the portion formed on the bottom surface is referred to as 13a2. In addition, the portion of the second layer 13b formed on the side of the water storage section 10 is referred to as 13b1, and the portion formed on the bottom surface is referred to as 13b2.

[0062] like Figure 3As shown, a ring-shaped sheathed heater 14 as an electric heating unit connected to the bottom surface of the water storage part 10 is arranged at the lower side of the water storage part 10, and the water stored in the water storage part 10 can be heated by the sheathed heater 14 to boil the hot water. In addition, although not shown in the figure, in the electric kettle described in this embodiment, the sheathed heater 14 is formed as a roughly annular member having an outer diameter slightly smaller than the outer diameter of the water storage part 10. The part of the sheathed heater 14 on the handle 2 side is not formed into a ring shape but is open, and the wiring connecting the power circuit not shown in the figure and the sheathed heater is connected to the open end.

[0063] In addition, a temperature sensor 15 for detecting the temperature of the water storage section 10 is arranged inside the arrangement portion of the armored heater 14 on the bottom surface of the water storage section 10. Based on the temperature of the bottom surface of the water storage section detected by the temperature sensor 15, a control circuit (not shown) controls the energization of the armored heater 14 to make the water in the water storage section 10 boil efficiently, and, for example, when the temperature detected by the temperature sensor 15 rises sharply, when it is suspected that a sufficient amount of water is not added to the water storage section 10, a safety process of stopping the energization of the armored heater 14 is performed to prevent empty boiling.

[0064] The power supply stand 4 on which the main body 1 of the electric kettle is placed has a setting surface 22 of a shape corresponding to the lower surface 21 of the bottom of the main body 1. When the lower surface 21 of the main body 1 is placed on the setting surface 22, the power plug 23 of the main body 1 is engaged with the power socket 24 of the power supply stand 4. When the main body 1 is placed on the power supply stand 4, the power supplied to the power supply stand 4 via a power cable (not shown) inserted into a commercial power supply can be supplied to the armored heater 14 arranged at the lower part of the main body 1.

[0065] In this way, the electric kettle shown in this embodiment heats the water stored in the water storage part 10 to boil the hot water while the main body 1 is placed on the fixed surface 22 of the power supply stand 4. After the hot water is boiled, the main body 1 can be removed from the power supply stand 4 and carried by the handle 2. In addition, by holding the handle 2 and tilting the main body 1, the hot water boiled by the water storage part 10 in the main body 1 can be poured into a coffee cup or the like, and the main body 1 can also be placed alone at a desired position such as on a table.

[0066] In the electric kettle illustrated in this embodiment, the cover body 3 has a locking mechanism for closing the upper surface of the main body, and further, a tip-over water stop mechanism is arranged inside the cover body 3 to prevent hot water from overflowing even in the event of accidental tipping. However, a detailed description of the internal mechanism of the cover body 3 including the tip-over water stop mechanism is omitted.

[0067] In addition, the overall structure of the electric kettle described in this embodiment is a conventionally known structure, and is merely an example showing a specific structure of the electric kettle.

[0068] <Coating on the inner surface of heating cooking containers>

[0069] (Ceramic coating)

[0070] Hereinafter, the ceramic coating layer 13 which is a coating film made of a sintered body of an inorganic substance and formed on the inner surface of the water storage portion 10 which is a heating cooking vessel will be described.

[0071] like Figure 3 As shown, in the water storage part 10 of the heating cooking container of this embodiment, a ceramic coating 13 is applied to the inner surface of a stainless steel inner container 12. The ceramic coating 13 is composed of two layers, a first layer 13a formed on the surface of the inner container 12, and a second layer 13b stacked on the first layer 13a.

[0072] The ceramic coating 13 can be formed by a so-called wet-on-wet method, that is, a colloidal sol is formed by dispersing a solution of a metal organic compound (metal alkoxide) or an inorganic compound in water, etc. First, a first layer 13a is coated on the inner surface of the kettle container as the coated part by a spray method, and then the colloidal sol is coated on the first layer 13a by a spray method to form a second layer 13b. Then, the first layer 13a and the second layer 13b are heated and calcined to sinter the solid oxide to form a film. The calcination conditions can be set at 200°C to 300°C for about 15 minutes to 20 minutes. After the film is formed, it becomes SiO 2 Sintered bodies of inorganic substances (oxides).

[0073] In the water storage part 10 of the electric kettle of the present embodiment, a non-transparent TiO2 film is used as the first layer 13a of the ceramic coating 13 and is modified to TiO2 by irradiation with a UV laser beam described later. 3 O 5 , and the color changes from bright gray to black pigment TiO 2 .

[0074] In addition, the ceramic coating 13a1 as the first layer may be formed by, for example, 2 TiO used as white pigment 2 , and the white color before UV laser irradiation is changed to black after irradiation. In addition, for example, Cr as a black pigment can be used. 2 O 3 Or carbon black, and change it from black before UV laser irradiation to brown after irradiation.

[0075] As the second layer 13b of the ceramic coating 13, SiO2, which is a light-transmitting material, is used. 2 . In addition, the so-called light transmittance of the second layer 13b refers to the state in which the color of the first layer 13a as the lower layer can be visually recognized when calcined into the ceramic coating 13. In the water storage portion 10 of the heating cooking container of this embodiment, the color of the first layer 13a is changed by irradiating the ceramic coating 13 with UV laser, thereby forming a water volume scale line indicating the amount of water contained in the water storage portion 10. The second layer 13b only needs to have light transmittance that allows the user to confirm the water volume scale line formed in the form of the change in color of the first layer 13a, and is not limited to a colorless and transparent water volume scale line, and a colored water volume scale line can also be used.

[0076] As the second layer of the ceramic coating 13b, for example, a SiO 2 Ceramic coating with silver mica dispersed in it, or pigments in SiO 2 The film is colored in a desired color of the ceramic coating. In addition, by coating glass as the second layer 13b, the water storage unit 10 can be made to have high transparency and patterns such as water volume scale lines formed on the first layer 13a can be more easily visually recognized.

[0077] From the viewpoint of preventing peeling, the film thickness of the ceramic coating 13 is preferably set to about 30 μm as a whole. As described later, in the water storage unit 10 described in this embodiment, when the water level scale line is formed by irradiation of UV laser, the second layer 13b remains as a surface protection film. Therefore, it is preferred that the film thickness of the second layer 13b is set to about 10 μm to 15 μm, and the film thickness of the first layer 13a is set to about 15 μm to 20 μm.

[0078] In addition, as a coating film of a sintered body containing an inorganic substance formed on the inner surface of the heating cooking container, the ceramic coating is representative, and as a coating method, in addition to the sol-gel method, various known methods such as an enameling method, a chemical vapor deposition method, a physical vapor deposition method, sputtering, a spraying method such as an oxyacetylene flame or plasma jet processing can be used. In addition, as an inorganic material forming a coating film of a sintered body described in this specification, in addition to ceramics made of natural raw materials such as clay, feldspar, and quartz (so-called old ceramics), new ceramics made of artificial minerals (or modern ceramics), alumina (Al 2 O 3), silicon carbide (SiC), titanium nitride (SiC) and other industrial ceramics, and further include a wide range of inorganic materials such as acrylic glass, borosilicate glass, quartz glass and other glasses. In addition, two or more materials of these various ceramics or various glasses can also be formed into a multilayer film. For example, by using the lower layer as a ceramic coating, the strength can be improved, and by using the upper layer as a glass film, the antifouling property and design can be improved. The hydrophilicity and water repellency of glass can be adjusted by the components used, so a preferred coating can be formed according to the product selection.

[0079] (Laser Processing)

[0080] In the water storage part 10 of the electric kettle described in this embodiment, the surface of the ceramic coating 13 formed on the inner surface is laser processed using a UV laser. Water volume scale lines indicating the amount of liquid contained in the water storage part 10 are formed on the side surface of the water storage part 10 by laser processing using a UV laser. In addition, the surface of the bottom surface of the water storage part 10 is roughened by laser processing using a UV laser, thereby improving the hydrophilicity of the bottom surface of the water storage part 10.

[0081] The UV laser irradiated onto the ceramic coating 13 formed on the inner surface of the water storage portion 10 described in this embodiment has a wavelength of 355 nm, which is 1 / 3 of the fundamental wavelength laser (1064 nm), and is called a third harmonic generation (THG) laser. The UV laser is generated by aligning the fundamental wavelength with a green laser of 532 nm (green wavelength) converted by a nonlinear crystal, and then passing through another nonlinear crystal, thereby converting it to a wavelength of 355 nm.

[0082] Compared with the fundamental wavelength laser or green laser, the UV laser has the characteristics of high absorption rate to the raw material and good absorption of the irradiated light by the irradiated surface. Therefore, when using UV laser for marking, it is not necessary to increase the power beyond the necessary level and can perform efficient laser processing. In addition, due to the high absorption efficiency, even when irradiating materials with high reflectivity such as metal, no unnecessary thermal damage will be caused. Furthermore, it has the advantages of low energy of photons and the ability to directly break the molecular bonds of the irradiated object for decomposition processing.

[0083] By using a UV laser having such characteristics to laser process the ceramic coating 13 formed on the inner surface of the water storage portion 10, significant thermal damage will not be caused to the ceramic coating 13, so that water volume scale lines can be preferably formed on the side or the bottom surface can be roughened.

[0084] (Formation of water level scale lines)

[0085] Figure 4This is an image diagram for explaining the irradiation state of the laser beam when the water level scale lines are formed on the inner side surface of the water storage part of the electric kettle described in this embodiment.

[0086] As described above, the side surface of the water storage portion 10 of the electric kettle described in this embodiment is formed with a layer containing TiO on the inner surface of the metal inner container 12. 2 、SiO 2 A first ceramic coating layer 13a1 is formed, and a layer including SiO is stacked on the first ceramic coating layer 13a1. 2 The second layer of ceramic coating 13b1.

[0087] The two ceramic coating layers 13a1 and 13b1 are irradiated with UV laser 30, so that the first layer 13a1 on the lower side is modified and its color is changed. In the water storage part 10 of the electric kettle of this embodiment, by using a laser marking device as an irradiation unit of the UV laser, the modified part 31 of the first layer 13a1 can be controlled, and the color can be changed in a desired pattern, so that the required number of scale lines can be formed at the accurate position. In addition, the second layer 13b1 of the part irradiated by the UV laser 30 is modified and scraped off to form a depression 32, but by adjusting the output of the UV laser 30, as shown in FIG. Figure 4 A portion of the second layer 13b1 on the surface shown remains on the surface of the first layer 13a1.

[0088] In addition, it is considered that in the modified portion 31 of the first layer 13a1, the surface is also slightly depressed by UV laser irradiation, but since the second layer 13b1 remains as described above, it is considered that there is no significant effect on the entire ceramic coating 13.

[0089] Thus, in the water storage part 10 described in the present embodiment, the modified portion 31 of the first layer 13a1 formed as the water level scale line is covered by the second layer 13b1 and is not exposed, so that it can be prevented from being strongly rubbed or contacted with detergents, etc., such as when the water storage part 10 is cleaned. Therefore, it is possible to avoid the water level scale line from peeling off or fading in color, and form a water level scale line with high durability. In addition, since the water level scale line is formed by utilizing the color change caused by the modification of the ceramic coating 13a itself formed as the first layer, compared with the prior art in which a part of the coating film is scraped off and the concave part thereof is filled with ink to form the water level scale line, there is no problem of environmental load or safety to the human body.

[0090] Furthermore, as described above, in the water storage unit 10 of the present embodiment, the ceramic coating 13 is irradiated with UV laser light to modify the first layer 13a1 to form a scale pattern that can be visually recognized sufficiently, and it is necessary to leave the second layer 13b remaining in the portion irradiated with the UV laser light 30. As a method of achieving the irradiation intensity of the UV laser light 30 that enables such a preferred laser processing, in addition to a method of adjusting the intensity of the UV laser light 30 itself in the laser marking device used, a method of deliberately shifting the focus (focal point) position of the UV laser light 30 from the position of the surface of the ceramic coating 13 irradiated with the UV laser light 30 to achieve a defocused state can be used.

[0091] Figure 5 (a) to Figure 5 (c) is an image diagram for explaining the change of the beam spot of the processed surface based on the relationship between the processed surface of the ceramic coating irradiated with the UV laser and the position of the focal point of the UV laser.

[0092] Figure 5 (a) shows the state where the focal point of the UV laser is far from the processing surface. Figure 5 (b) shows the state of the so-called positive focus where the processing surface coincides with the focal point of the UV laser. Figure 5 (c) shows a state where the processing surface is farther than the focal point of the UV laser.

[0093] In addition, the inventors have confirmed that: Figure 5 The case where the focus point 33 shown in (a) is far from the processing surface, and Figure 5 In the case where the focal point 33 shown in (c) is close to the processing surface, the degree of change in the size of the spot diameter of the UV laser 30 relative to the size of the distance X1 and the distance X2 is approximately the same. Therefore, when forming a water volume scale pattern on the water storage part 10 of the electric kettle described in this embodiment, in order to reduce the damage to the coating film caused by the proximity of the processing surface (curved surface or positional deviation, etc.) of the workpiece to the laser, the processing surface is placed closer to the position of the focal point of the UV laser 30. Figure 5 In the state shown in (a), the change in spot diameter when the distance X1 between the processing surface and the focal point 33 changes by 0.1 mm is set to 1, and the defocus amount X1 is changed to study the irradiation energy of the irradiated UV laser 30.

[0094] More specifically, within the value of laser power specified in the laser marking device (as an example, 20, 30, 40, etc. are selected), the defocus amount X1 is changed (as an example, -20, -30, -40, ... -100, etc. are selected), and the UV laser 30 is actually irradiated on the side of the inner container 12 to visually confirm the amount of color change caused by the degree of modification of the first layer 13a1.

[0095] In addition, whether the second layer 13b1 plays a protective function as an outer coating of the first layer 13a1 due to the modification based on the irradiated UV laser 30 is confirmed by a peeling test in which a tape (for example, cellophane tape (registered trademark), width 18 mm, manufactured by NICHIBAN Co., Ltd.) is affixed to the part where the color of the first layer 13a1 is changed by irradiating the side of the water storage part 10 with UV laser and then peeling it off by hand.

[0096] Through the inventor's research, it was confirmed that by adjusting the value of the UV laser irradiation intensity and the value of the defocus amount X1, the color change of the first layer 13a1 can be fully visually identified, and the following conditions can be found: even if the UV laser 30 is irradiated, a certain thickness of the second layer 13b1 remains without causing peeling of the ceramic coating 13 based on the peeling test.

[0097] In forming the water level scale lines using the laser marking device, the pulse frequency of UV laser irradiation and the moving speed of the irradiation position of the UV laser, that is, the scanning speed can be adjusted.

[0098] When the pulse frequency of UV laser irradiation increases, the pulse width of the irradiated laser increases, and the peak energy tends to decrease. In this case, the irradiation time of the laser beam on the irradiated surface increases, and the irradiated surface is greatly affected by heat.

[0099] When the ceramic coating shown in this embodiment is irradiated with UV laser, if the thermal effect on the coating is large, the damage to the second layer on the surface becomes larger, and peeling is more likely to occur. Therefore, it can be seen that when forming the water volume scale line on the side of the water storage part, it is preferable to set the pulse frequency to a low level.

[0100] In the study on the irradiation spacing of UV laser, it was confirmed that: by reducing the irradiation spacing, the modification of the first layer becomes greater, and the color change becomes greater, thereby improving the visual recognition of the scale lines. On the other hand, the damage to the second layer becomes greater, and the second layer is easily peeled off, thereby reducing the durability of the coating.

[0101] Based on the above characteristics, it can be confirmed that the preferred conditions for forming the water volume scale line on the side of the water storage part 10 of the electric kettle in this embodiment are: in the UV laser with a wavelength of 355nm, the laser power is 50%, the scanning speed is 750mm / s, the pulse frequency is 50kHz, the spot variable amount (X1) is -60mm (the spot diameter is blurred from 50μmφ to 137μmφ by defocusing), the filled line interval is 15μm, and the number of prints is 1. In addition, the irradiation conditions of the UV laser are different depending on the material and thickness of the coating film of the first layer 13a1 and the second layer 13b1, and the tilt angle of the UV laser relative to the side when it is incident. Therefore, it is studied from the viewpoint of whether the water volume scale line has sufficient visual recognition by modifying the first layer 13a1 and whether the thickness of the second layer 13b1 that is sufficient to have durability as an outer coating film can be ensured, and of course, appropriate irradiation conditions should be set.

[0102] Figure 6 This is a diagram showing water volume scale lines formed on the side surface of the water storage unit under the above-mentioned preferred conditions.

[0103] In addition, as a laser marking device using UV laser, a laser marker (Laser Marker) MD-U1020 (product name) manufactured by KEYENCE Co., Ltd. was used. In addition, since the inner diameter of the water storage part is 170 mm, and the position of the scale line 200 located at the bottom of the side is 106 mm from the upper end of the water storage part, it is impossible to form all the water volume scale lines at once within the sweeping range of the irradiation beam on the horizontal plane of the laser marking device. Therefore, the scale lines are formed twice, divided into the water volume scale lines located at the bottom of the side and the water volume scale lines located above the scale line 600.

[0104] (Roughening of container bottom surface)

[0105] In the water storage part of the electric kettle described in this embodiment, while the water volume scale lines are formed on the side surface, the bottom surface is irradiated with UV laser for surface treatment, making the bottom surface rough, thereby improving hydrophilicity. The content is described below.

[0106] Figure 7 (a) Figure 7 (b) is an image diagram showing changes in the concavo-convex shape of the bottom surface of the water storage portion of the electric kettle according to the present embodiment caused by irradiation with UV laser. Figure 7 (a) shows an image of a curve representing the surface state before irradiation with UV laser, Figure 7 (b) shows an image of a curve indicating the surface state after UV laser irradiation.

[0107] The UV laser irradiation of the bottom surface of the water storage part 10 was performed using the laser marker (Laser Marker) MD-U1020 (product name) manufactured by KEYENCE Co., Ltd., and the processing was performed under the conditions of laser power 80%, scanning speed 4000mm / s, pulse frequency 100kHz, filled line spacing 0.040mm, and printing times (number of repetitions of light beam irradiation) 4 times. The processing time required was 265.4Sec.

[0108] Knowable Figure 7 The surface of the ceramic coating 13 before irradiation with UV laser shown in (a) is a relatively rough concave-convex surface with an arithmetic mean roughness Ra of 0.82 (μm). In contrast, after irradiation with UV laser, Figure 7 As shown in (b), it becomes along the Figure 7 The concavoconvex shape shown in (a) is formed with a fine concavoconvex state with a surface roughness Ra of 1.65 (μm). In addition, the film thickness of the coating before and after UV laser irradiation is 21.5 μm before irradiation, while it is 20.1 μm after irradiation. It can be understood that the change in film thickness due to UV laser irradiation is small and the damage to the coating is not great.

[0109] The surface roughness of the coating film was measured using a Taylor Hobson surface roughness tester Surtronic DuO (trade name).

[0110] In this way, by irradiating the ceramic coating 13 formed on the bottom surface of the water storage part 10 with UV laser, a rough surface state with fine concave-convex shapes is formed on the coating surface, and the surface of the ceramic coating on the bottom surface can be changed from the original water-repellent surface of the ceramic coating to the hydrophilic surface.

[0111] Figure 8 This is a diagram showing the state of water remaining on the bottom surface after water is put into the water storage portion irradiated with UV laser.

[0112] like Figure 8 As shown, on the bottom surface irradiated with UV laser, a water film remains even when water having a larger surface tension than alcohol is used, and it can be confirmed that the bottom surface has high hydrophilicity.

[0113] Next, regarding the roughening of the bottom surface of the water storage unit 10 by irradiating the bottom surface with UV laser, the difference between the case of using UV laser and the case of using hybrid laser was examined.

[0114] The laser marking device used for irradiating the hybrid laser used as a comparison object is a hybrid laser MD-X2520 (product name) manufactured by KEYENCE Co., Ltd., which is based on YVO4 The wavelength of the light source is a standard wavelength of 1.064nm. The mixed laser irradiation conditions are laser power 40%, scanning speed 8000mm / s, pulse frequency 100kHz, filled line interval 0.080mm, and printing number 1. The processing time is 17.3Sec.

[0115] Under the above conditions, the surface roughness Sa of the ceramic coating on the bottom surface after irradiation with the mixed laser is 1.0 (μm), which is not much different from the surface roughness Sa value of 0.8 (μm) after irradiation with the UV laser. However, the depth of the resulting unevenness is 9.9 μm, which is larger than the depth of 3.5 μm of the unevenness when the surface is roughened using the UV laser.

[0116] Fig. 9 (a) Fig. 9 (b) is a diagram showing the results of a temperature rise test in the water storage portion caused by differences in lasers used for roughening the bottom surface. Fig. 9 (a) is the data when UV laser is used for surface roughening. Fig. 9 (b) is data when a hybrid laser is used for roughening.

[0117] The temperature rise test is measured in the following manner: a ceramic coating adjusted so that the film thickness of the bottom surface becomes 25 μm is formed on the bottom surface of the water storage part on the inner surface, and UV laser and mixed laser are irradiated under the above conditions to roughen the entire surface of the bottom surface, and then 1000 ml of water equivalent to room temperature (about 23°C) is put into it. In this state, the switch of the electric kettle is turned on to boil the hot water.

[0118] like Fig. 9 As shown in (a), in the water storage section 10 whose bottom surface is roughened by UV laser, the surface temperature of the heater tube of the armored heater represented by the symbol 51 in the figure can be maintained even after rising to the specified 190°C, and the temperature of the water inside the water storage section 10 can be maintained constant after rising to 100°C about 4 minutes after the start of heating. This means that the bottom surface of the water storage section 10 becomes hydrophilic by roughening the ceramic coating 13 on the bottom surface of the water storage section 10, and large bubbles are not easily formed on the bottom surface. Therefore, the temperature of the water in the water storage section 10 can be accurately measured by a temperature sensor that detects the temperature of the outer surface portion of the bottom surface of the water storage section 10, thereby correctly performing the on-off control of the armored heater.

[0119] On the other hand, Fig. 9In the case where the ceramic coating 13 on the bottom surface of the water storage unit 10 is roughened by the mixed laser, the curve diagram of the symbol 53 indicating the surface temperature of the armored heater shows that it rises sharply from the time point of 4 minutes after the start and stops after reaching about 350°C. At this time, the water temperature in the water storage unit shown by the symbol 54 is Fig. 9 In the case of the surface roughening by UV laser shown in (a), the temperature reaches about 100° C. 4 minutes after the start in substantially the same manner.

[0120] The bottom surface of the water storage part 10 is roughened by the mixed laser. Fig. 9 In the water storage part shown in (b), the laser output is strong, and when you want to form bumps and depressions on the coating that appear through UV laser, the damage to the coating is large, and the printing conditions need to be restricted. As a result, it is believed that the wettability of the bottom surface has not changed significantly, and the surface of the ceramic coating 13 still maintains a hydrophobic surface state. Therefore, the bubbles generated by the rise in water temperature do not leave the bottom surface and grow significantly, thereby forming an insulating layer of air. Therefore, it is believed that the heat supplied from the armored heater is not transferred to the water, causing the temperature of the bottom portion including the coating surface to rise. As a result, the water temperature did not reach 100°C, but the temperature regulator malfunctioned, resulting in so-called dry burning.

[0121] Thus, even if the ceramic coating 13 on the bottom surface of the water storage portion 10 is irradiated with laser, the wettability of the bottom surface due to roughening cannot be sufficiently improved in the surface treatment using hybrid laser, and the bottom surface still maintains the hydrophobic state of the ceramic coating.

[0122] Next, the difference in effect between the hydrophilization treatment of the bottom surface of the water storage portion 10 by UV laser and the hydrophilization by polishing treatment performed in the related art was investigated.

[0123] Fig.10 The diagram explains the difference in damage to the ceramic coating caused by surface roughening using UV laser and surface roughening using mechanical polishing.

[0124] Fig.10 The ○ mark represented by symbol 61 represents the pinhole value in the thermal cycle test when the bottom surface is roughened by the UV laser described in this embodiment, and the × mark represented by symbol 62 represents the pinhole value in the thermal cycle test of the water storage part after the bottom surface is roughened by grinding treatment as a comparative example.

[0125] In addition, as the water storage part 10 subjected to the roughening treatment by UV laser, the water storage part used in the temperature rise test was used directly. On the other hand, as for the water storage part 10 as a comparative example, a ceramic coating construction container whose average thickness of the coating film on the bottom surface was adjusted to 25 μm was used, and a non-woven fabric surface treatment material Scotch-Brite (registered trademark) 8447P (trade name, manufactured by 3M (three M) Co., Ltd.) cut into a disc shape was pressed onto the processed part by using a toggle clamp with a load of 1.3 kgf to 1.5 kgf, and a grinding treatment was performed for 3 minutes with 400 to 450 rotational vibrations per minute.

[0126] in addition, Fig.10 The pinhole value shown is obtained by boiling cold water adjusted to 5°C, discarding the hot water after boiling, and then putting in cold water at 5°C, cooling the water storage part, and then repeating the boiling again, for a water storage part whose bottom surface is roughened by UV laser and a water storage part whose bottom surface is polished by Scotch-Brite (registered trademark). After a predetermined number of times, a current value flowing when a voltage of 2.0V is applied between the coating film surface and the container is measured. As a result of the thermal cycle test, cracks are generated in the ceramic coating film to form pinholes, and the value of the current flowing increases as the number of pinholes increases. Therefore, the durability of the ceramic coating film roughened by UV laser irradiation and the ceramic coating film roughened by mechanical polishing can be measured.

[0127] like Fig.10 As shown, it can be seen that in the ceramic coating film roughened by UV laser irradiation, the change in the current value of the flow disappears from about 100 times of the thermal cycle test, and the degree of cracking in the coating film due to temperature change is small. On the other hand, in the ceramic coating film roughened by mechanical grinding, there is a tendency that the current value of the flow continues to increase as the number of thermal cycle tests increases. When the number of thermal cycle tests exceeds 300, the current value of the flow is 10 mA or more, which is a much larger value than the current value of 4 mA of the ceramic coating film roughened by UV laser.

[0128] According to the above situation, it can be confirmed that by irradiating UV laser to roughen the surface of the coating film, hydrophilicity can be ensured without causing major damage to the coating film. Therefore, in the water storage part 10 of the electric kettle shown in this embodiment, by irradiating UV laser to roughen the bottom surface, the bottom surface formed with the hydrophobic ceramic coating 13 can be modified to be hydrophilic, and the unfavorable situation of so-called premature cutting due to the inability to detect the accurate water temperature by the temperature sensor due to large bubbles generated on the bottom surface when the temperature rises can be avoided.

[0129] In addition, in the study to confirm the effect of roughening the bottom surface by UV laser, the entire bottom surface of the container was irradiated with UV laser to roughen the entire surface, but in the water storage part 10 of the electric kettle of this embodiment, it is not necessary to make the entire bottom surface hydrophilic. In particular, by using a laser marking device that can irradiate a predetermined position represented by the XY coordinates of a plane as an irradiation object with UV laser as the irradiation unit of UV laser, the UV laser can be selectively irradiated to the part of the bottom surface of the water storage part 10 that is preferably hydrophilic.

[0130] Fig.11 (a) Fig.11 (b) is an image diagram for explaining the position where the bottom surface of the electric kettle of the present embodiment is roughened by UV laser. Fig.11 (a) is a plan view showing the portion of the bottom surface irradiated with UV laser, Fig.11 (b) is a cross-sectional view showing the relationship between the portion irradiated with UV laser light and the positions of the various members formed on the bottom surface of the water storage portion.

[0131] like Fig.11 As shown in (a), in the water storage part 10 of the electric kettle of this embodiment, the annular part 71 near the outer peripheral part of the bottom surface and the parts 72 protruding inward from two opposing parts of the annular part 71 are used as the roughened parts based on UV laser.

[0132] like Fig.11 As shown in (b), the annular portion 71 in the bottom surface of the water storage section 10 is a portion where the armored heater 14 as a heat source is arranged on the outer side of the bottom surface of the water storage section 10. In addition, the two portions 72 protruding inward are portions where the temperature sensor 15 for measuring the temperature of the outer side of the bottom surface of the water storage section 10 is arranged. In this way, by making the portion 71 facing the arrangement position of the electric heating unit as the heat source and the portion 72 facing the arrangement portion of the temperature sensor for detecting the temperature of the water storage section as the portions roughened by UV laser, it is possible to effectively prevent large bubbles from being generated on the bottom surface of the water storage section, and it is possible to boil hot water while accurately measuring the water temperature using the temperature sensor.

[0133] In addition, Fig.11 (a) Fig.11 In (b), if Fig.11 As shown in (b), a step difference is formed in the coating film due to the strength of the processing at the portion facing the configuration position of the heat source and the portion facing the temperature regulating portion, but the processing conditions can be made the same and processing without step difference can be performed at the portion facing the heat source and the portion facing the temperature regulating portion.

[0134] In addition, Fig.11 (a) Fig.11In (b), the case where a sheathed heater is used as the electric heating unit is described. However, when the electric heating unit is not a sheathed heater, it is also preferable to roughen the surface of the position facing the arrangement position of the heating unit. For example, when the electric heating unit is a printing heater having a heating portion arranged on a plane on a substrate, it becomes Fig.11 The portion facing the armored heater shown in (a) is a wide area, but it is preferred to roughen the portion facing the brush heater.

[0135] In addition, in the example described above, an example is shown in which both the portion facing the configuration position of the heater serving as the heating unit and the portion facing the configuration position of the temperature sensor are roughened, but by roughening either the position facing the heating unit or the position facing the temperature sensor, it is also possible to accurately grasp the temperature of the bottom portion of the water storage section 10, adjust the temperature inside the water storage section, and thus boil hot water.

[0136] As described above, the heating cooking container as the water storage part of the electric kettle described in this embodiment has a coating film containing a sintered body of an inorganic substance formed on the inner surface of the metal inner container, so compared with the surface treatment process using fluororesin used in the past, there is no concern about safety caused by the use of fluorine. In addition, by irradiating the formed coating film with UV laser to modify its surface, the color of the part irradiated with UV laser can be different from that of other parts to draw a predetermined pattern such as a water volume scale line, and the surface of the coating film irradiated with UV laser is roughened, so that the surface of the coating film can be hydrophilized.

[0137] As a result, a water level scale line with excellent durability can be formed at low cost, and the surface of the hard coating can be converted from hydrophobic to hydrophilic, which can effectively avoid undesirable situations such as premature shutdown caused by inability to accurately measure the temperature of the internal water.

[0138] In addition, in the above-mentioned embodiment, a laminated body of two hard coating layers, namely the first layer and the second layer, is formed on the inner surface of the water storage part of the electric kettle, and a water volume scale line is formed on the side surface and the bottom surface is roughened. However, in the water storage part of the heating cooking container of this embodiment, in addition to the side surface, pattern formation based on the modification of the first layer can be performed, or a part of the side surface can be roughened as needed.

[0139] Furthermore, when it is not necessary to form a pattern such as water level scale lines by irradiating the hard coating with UV laser, the hard coating may be formed into a single layer and only laser processing may be performed to roughen the surface with UV laser.

[0140] Next, as another specific example of the heating cooking container disclosed in the present application, an example of a case where the heating cooking container is used in an inner pot of a rice cooker will be described.

[0141] Fig.12 It is a cross-sectional view showing the entire structure of a rice cooker using an inner pot as a heating cooking vessel according to the present embodiment.

[0142] like Fig.12 As shown, the electric rice cooker using the heating cooking container of this embodiment as the inner pot 120 comprises: a main body 100; and a lid 110, which is arranged above the main body and covers the inner pot 120 accommodated inside the main body. The lid 110 can be opened as follows: the user presses the front side (user side, Fig.12 The lock button 111 is unlocked by pressing the lock button 111 on the rear side ( Fig.12 The hinge mechanism 112 (upper side) of the inner pot 120 is rotated to open the upper space of the inner pot 120. In addition, various mechanisms currently known can be appropriately adopted as the internal structure of the rice cooker other than the inner pot, so detailed description is omitted here.

[0143] exist Fig.12 In the rice cooker shown in FIG. 1 , a coating film containing a sintered body of an inorganic substance is formed on the inner surface of the inner pot 120. Figure 1 to Figure 3 The water storage part of the electric kettle whose structure is shown in the figure. Similarly, regarding the laser processing using UV laser on the coating 121a formed on the bottom surface of the inner pot 120 and the coating 121b formed on the side, the shape or position of the display pattern to be formed and the roughening unit for the required parts can be appropriately selected.

[0144] exist Fig.12 In the case of the inner pot of the rice cooker shown, the film thickness of the coating film 121a on the inner surface of the bottom of the inner pot is 30 to 40 μm, and the film thickness of the coating film 121b on the side surface is 20 to 30 μm.

[0145] In addition, if Fig.12As shown in FIG. 1 , in the rice cooker, a plurality of heaters are arranged to surround the entire inner pot: a bottom surface heater 131 arranged to face the bottom surface of the inner pot, a second heater 132 arranged to face the bottom surface vicinity of the side surface, and a third heater 133 arranged near the upper opening of the side surface. The heat supplied from these heaters 131, 132, and 133 is controlled according to the cooking content to cook rice. The coating formed inside the inner pot can also be controlled to change a part or all of the surface state corresponding to the facing parts of the arrangement positions of these heaters, so that a coating under a more preferred condition is formed on the inner surface of the inner pot. In addition, as the heater of the rice cooker, an induction heating (IH) heater of an induction heating method is sometimes used as a main heating unit for heating and cooking rice, and an electric heating method heater is used for keeping the rice warm after cooking. Different types of heaters are used in one rice cooker. Therefore, as the coating formed on the inner surface of the inner pot, it is more preferred to select a coating with a more appropriate surface morphology according to the characteristics of each heating unit.

[0146] In addition, for example Fig.12 As shown in FIG. 1 , the electric rice cooker is also provided with a temperature sensor 134 which is urged by a spring or the like in a manner of contacting the center of the bottom of the inner pot. As in the case of the electric kettle, for example, the surface roughness of the coating film 121a may be made smaller than that of other parts of the bottom surface by laser processing at the portion facing the temperature sensor 134, i.e., the center portion of the bottom surface of the inner pot. The temperature of the inner pot of the electric rice cooker can be more accurately grasped by the temperature sensor 134.

[0147] As described above, the heating cooking container disclosed in the present application has a coating film containing a sintered body of an inorganic material having a laminated structure including a non-transparent first layer and a light-transmitting second layer formed on its inner surface, a specified portion of the first layer is modified to a color different from other portions, and the surface of the second layer as the modified portion is roughened.

[0148] By using a coating film including a sintered body of an inorganic substance having such a laminated structure, a predetermined pattern can be formed by the modified portion of the first layer, or the surface of the coating film can be modified to be hydrophilic by roughening the surface of the second layer. As a result, compared with a surface treatment film formed by fluororesin processing, there is no safety problem, and a surface treatment film that is strong against external forces applied during use such as friction can be formed, and in particular, it can prevent the food being cooked from adhering to the inner surface of the container during heating and cooking, thereby causing dirt.

[0149] The method for manufacturing a cooking container disclosed in the present application includes: a step of forming an inorganic hard coating film on the inner surface of the container; and a laser processing step of irradiating the hard coating film with UV laser to roughen the surface.

[0150] Therefore, a heating cooking container having a hard coating as follows can be realized: the surface properties can be modified to be hydrophilic without causing any more damage than necessary to the hard coating formed on the inner surface of the heating cooking container, and the durability is excellent. For example, problems such as noise or sudden boiling caused by large bubbles generated on the coating surface during boiling can be prevented, and the problem of false detection by the temperature sensor due to the formation of bubbles can also be avoided.

[0151] In addition, as the heating cooking container disclosed in the present application, in addition to the water storage part of the electric kettle and the inner pot of the rice cooker described in the above embodiment, various thermoses such as hand-held kettles, heating cooking plates such as hot plates, bread boxes of home bakers, containers of rotary cookers, large pots of coffee machines, etc. can also be widely used as cooking containers for cooking objects heated by the electric heating unit.

[0152] [Industrial Applicability]

[0153] The heating cooking container of the present invention is effectively used as a cooking container formed with a surface treatment film having high safety and durability.

Claims

1. A heating cooking container, which contains food to be cooked and is heated by an electric heating unit for cooking, wherein the heating cooking container is characterized in that: A hard coating film composed of a sintered body of an inorganic substance is formed on the inner surface. The hard coating film comprises: a non-transparent first layer; and a light-transmitting second layer stacked on the first layer. A predetermined portion of the first layer is modified to a color different from that of other portions, and a surface of the second layer as the modified portion is roughened.

2. The heating cooking container according to claim 1, wherein: The inorganic substance is at least one of ceramics and glass.

3. The heating cooking container according to claim 1, wherein: The first layer is formed of a material that changes color by photolysis.

4. The heating cooking container according to claim 1, wherein: The modified portion is formed on a side surface of the heating cooking container, and a scale line indicating a storage amount of the content is formed by the modified portion.

5. The heating cooking container according to claim 1, wherein: The modified portion is formed on a bottom surface of the heating cooking container.

6. The heating cooking container according to claim 5, wherein: The modified portion is a portion of the bottom surface that faces a location where the electric heating unit is disposed and / or a portion that faces a location where a temperature sensor that detects a temperature of the cooking container is disposed.

7. The heating cooking container according to any one of claims 1 to 6, wherein: The heating cooking container is a water storage part of an electric kettle.

8. The heating cooking container according to any one of claims 1 to 6, wherein: The heating cooking container is an inner pot of an electric rice cooker.

9. A method for manufacturing a heating cooking container, wherein a food to be cooked is contained inside and cooked by heating with an electric heating unit, characterized in that: include: a coating film forming step of forming a hard coating film including a sintered body of an inorganic substance on the inner surface of the heating cooking container; as well as In the laser processing step, the surface of the formed hard coating film is irradiated with ultraviolet laser to roughen the surface.

10. The method for manufacturing a cooking container according to claim 9, wherein: In the coating film forming step, a non-transparent first layer and a light-transmitting second layer stacked on the first layer are formed.

11. The method for manufacturing a cooking container according to claim 10, wherein: The laser processing step modifies the first layer on the side surface of the heating cooking container, and forms scale lines indicating the amount of food to be cooked contained in the heating cooking container.

12. The method for manufacturing a cooking container according to claim 9, wherein: By the laser processing step, at least one of a portion of the bottom surface of the cooking container facing the arrangement position of the electric heating unit and a portion facing the arrangement position of a temperature sensor for detecting the temperature of the cooking container is roughened.

Images