JP2017131398A - Rice cooker and container - Google Patents

Abstract

An object of the present invention is to provide a rice cooker capable of reducing uneven cooking and making the surface of the rice bowl into a mountain shape.
A rice cooker includes a pan-like container 5 having a bottom 51 and a peripheral wall 52 provided on the outer periphery of the bottom, a main body that houses the pan-like container, and a heating unit that heats the pan-like container. Is provided. A plurality of surface portions having different hydrophilic properties are provided on the inner surface of the bottom portion. The plurality of surface portions include a first surface portion 50a and a second surface portion 50b that is disposed on the outer peripheral side of the first surface portion and has higher hydrophilicity than the first surface portion.
[Selection] Figure 5

Description

  The present invention relates to a rice cooker that cooks rice by heating a container, and the container.

  Some rice cookers have a water-repellent coating formed on the inner surface of the container in order to prevent sticking of rice and improve cleanability. When a water-repellent coating film is formed, bubbles generated by boiling are difficult to separate from the inner surface of the container, and many of the bubbles rise along the side surface of the container. Therefore, the effect of convection of the rice cooking liquid is not sufficiently obtained, and cooking unevenness may occur. Moreover, since air bubbles rise along the side surface of the container, the cooked surface has a concave shape at the center, and a mountain-like shape reminiscent of deliciousness cannot be obtained.

  Therefore, in the rice cooker described in Patent Document 1, a coating film containing water-repellent PFA or PTFE and a hydrophilic filler is formed on the inner surface of the bottom of the container, and the filler is formed on the surface of the coating film. Some are exposed. As a result, many small bubbles are generated from the bottom of the container to promote convection.

  Moreover, in the rice cooker described in patent document 2, the several recessed part used as the starting point of a boiling is formed in the inner surface of the bottom part of a container. Thereby, it is easy to detach | leave a bubble from the bottom part of a container, and the convection is stabilized.

JP 2009-034378 A (see paragraphs 0028-0033) International Publication No. 2012/153444 (see paragraph 0063)

  In the conventional rice cooker described above, convection is promoted by controlling the size of bubbles, but the cooked surface does not have a mountain shape (that is, a shape reminiscent of plump taste).

  This invention is made | formed in order to solve said subject, and it aims at providing a rice cooker which reduces cooking unevenness and a cooked surface becomes a mountain shape.

  The rice cooker according to the present invention includes a container having a bottom part and a peripheral wall part provided on the outer periphery of the bottom part, a main body part that accommodates the container, and a heating part that heats the container. A plurality of surface portions having different hydrophilic properties are provided on the inner surface of the bottom portion. The plurality of surface portions include a first surface portion and a second surface portion that is disposed on the outer peripheral side of the first surface portion and has higher hydrophilicity than the first surface portion.

  The container according to the present invention includes a bottom portion and a peripheral wall portion provided on the outer periphery of the bottom portion. A plurality of surface portions having different hydrophilic properties are provided on the inner surface of the bottom portion. The plurality of surface portions include a first surface portion and a second surface portion that is disposed on the outer peripheral side of the first surface portion and has higher hydrophilicity than the first surface portion.

  According to the present invention, among the first surface portion and the second surface portion of the bottom portion, the second surface portion on the outer peripheral side has high hydrophilicity, so that the bubbles are formed on the second surface portion before growing greatly. Easy to leave. Therefore, the amount of bubbles that reach the peripheral wall portion decreases, and bubbles that rise further inside increase. As a result, cooking unevenness can be reduced and the cooked surface can be shaped like a mountain.

It is sectional drawing which shows the structure of the rice cooker of Embodiment 1. FIG. It is sectional drawing (A) and top view (B) which show the structure of the pan-shaped container of Embodiment 1. FIG. It is sectional drawing (A) which shows typically the generation | occurrence | production state of the bubble at the time of providing a water-repellent coating film in a pan-like container, and sectional drawing (B) which shows typically the shape of the boiled surface. It is sectional drawing (A) which shows typically the generation | occurrence | production state of the bubble at the time of providing a hydrophilic coating film in a pan-like container, and sectional drawing (B) which shows the shape of the boiled surface typically. It is sectional drawing (A) which shows typically the generation | occurrence | production state of the bubble in the pan-shaped container of Embodiment 1, and sectional drawing (B) which shows the shape of the boiled surface typically. Sectional drawing (A) which shows the structure of the pan-shaped container of Embodiment 2 with the generation | occurrence | production state of a bubble, Sectional drawing (B) which shows the shape of the boiled surface typically, and sectional drawing which shows another structural example ( C). It is sectional drawing (A) which shows the structure of the pan-shaped container of Embodiment 3 with the generation | occurrence | production state of a bubble, and the top view (B) which shows the structure of a pot-shaped container. It is sectional drawing which shows typically the shape of the boiled surface of the pot-shaped container of Embodiment 3. FIG. It is sectional drawing (A) which shows the structure of the pan-shaped container of Embodiment 4 with the generation | occurrence | production state of a bubble, and the top view (B) which shows the structure of a pot-shaped container. It is sectional drawing which shows typically the shape of the boiled surface of the pot-shaped container of Embodiment 4. FIG. It is sectional drawing (A) which shows the structure of the pot-shaped container of Embodiment 5, and the top view (B) which shows the structure of a pot-shaped container. It is a figure which shows typically the movement state of the bubble in the pan-shaped container of Embodiment 5. FIG. It is a figure which shows the other structural example of the pan-shaped container of each embodiment.

  The rice cooker of each embodiment of the present invention will be described with reference to the drawings, taking a home-use IH (induction heating) rice cooker as an example.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a configuration of rice cooker 100 according to the first embodiment. The rice cooker 100 cooks the object to be heated by heating the pot-shaped container 5 containing the object to be heated (rice 200 and water 201 in the first embodiment) with the heating coil 3.

  The rice cooker 100 includes a main body 1 (main body portion) in which the pan-like container 5 is detachably accommodated, and a lid body 10 that opens and closes an opening of the main body 1. The main body 1 includes a container cover 2, a heating coil 3 as a heating unit and a pan bottom temperature sensor 4 disposed on the bottom portion 21 of the container cover 2 in a bottomed cylindrical main body case 1 a.

  The container cover 2 has a bottom portion 21 and a cylindrical peripheral wall portion 22 provided around the bottom portion 21, and has an opening on the upper side. The upper end edge of the peripheral wall portion 22 of the container cover 2 is fixed to the inner peripheral surface of the opening of the main body 1. A hole 2 a for attaching the pan bottom temperature sensor 4 is formed in the center of the bottom 21 of the container cover 2.

  Inside the container cover 2, a pan-like container 5 as a container is detachably accommodated. The pot-like container 5 is a container having a bottom 51 and a cylindrical peripheral wall 52 provided around the bottom 51 and having an opening on the upper side, and a heated object (here, rice 200 and water 201). ). The pan-like container 5 is made of a magnetic metal that generates heat by induction heating.

  The heating coil 3 is an induction heating coil disposed so as to face the bottom 21 of the container cover 2. Here, the heating coil 3 is composed of a single annular coil wound in a spiral shape around the central axis of the pan-like container 5 (the central axis C shown in FIG. 2A), and has an inner peripheral end. 3a and outer peripheral end 3b.

  The heating coil 3 is supplied with a high-frequency current through a power supply unit and an inverter circuit (not shown) under the control of the control unit 8 described later, and generates a high-frequency magnetic field. Due to the high-frequency magnetic field generated by the heating coil 3, an eddy current is generated in the pot-shaped container 5 made of a magnetic material, and Joule heat is generated by the eddy current and the resistance of the pot-shaped container 5.

  An electric heater such as a sheath heater may be used as the heating unit instead of the heating coil 3. Further, the arrangement of the heating coil 3 is not limited to the arrangement shown in FIG. For example, in addition to the position facing the bottom 21 of the container cover 2, the heating coil 3 may be disposed at a position facing the peripheral wall 22 of the container cover 2.

  A pot bottom temperature sensor 4 is disposed in the hole 2 a of the bottom 21 of the container cover 2. The pan bottom temperature sensor 4 is a thermistor, for example, and detects the temperature of the pan-like container 5. The pot bottom temperature sensor 4 is urged upward by an elastic member such as a spring and is in contact with the lower surface of the bottom 51 of the pot-like container 5. The pan bottom temperature sensor 4 outputs the detected temperature information to the control unit 8.

  In addition, the pan bottom temperature sensor 4 is not limited to a thermistor. The pan bottom temperature sensor 4 is a contact type temperature sensor that detects the temperature by contacting the pan-shaped container 5 and a non-contact type temperature sensor (for example, an infrared sensor) that detects the temperature without contacting the pot-shaped container 5. There may be.

  On one end side of the upper part of the main body 1 (left side in FIG. 1), a hinge part 6 is provided as a lid support part. The hinge part 6 supports the cover body 10 which covers the opening part of the main body 1 so that opening and closing is possible.

  The lid 10 has an outer lid 11 and an inner lid 12. The outer lid 11 constitutes an upper part and a side part of the lid body 10. A removable cartridge 14 is attached to the outer lid 11, and an operation display unit 15 is provided on the upper surface of the outer lid 11.

  An inner lid 12 is detachably attached to a lower surface of the outer lid 11 (a surface facing the pan-like container 5) via a locking member 13. An internal temperature sensor 16 is attached to the lower surface of the outer lid 11.

  The inner lid 12 covers the opening of the pan-like container 5. A packing 9, which is a sealing material that seals between the pot-like container 5, is attached to the outer peripheral edge of the inner lid 12. A hole 12a is formed in the inner lid 12, and an internal temperature sensor 16 attached to the outer lid 11 is inserted into the hole 12a.

  The internal temperature sensor 16 detects the temperature in the pot-like container 5 through the hole 12 a and outputs the detected temperature information to the control unit 8. The internal temperature sensor 16 can be composed of, for example, a thermistor.

  The inner lid 12 is formed with a steam port 12b through which steam generated in the pan-like container 5 enters and exits. The steam port 12 b communicates with the steam intake port 14 a of the cartridge 14. Note that a packing 11 a is attached to the outer lid 11 to close a gap on the outer periphery of the internal temperature sensor 16 inserted into the hole 12 a of the inner lid 12.

  The cartridge 14 includes a steam inlet 14a having a valve (not shown) that moves up and down according to the steam pressure generated during rice cooking, and a steam outlet that discharges the steam that has passed through the valve of the steam inlet 14a to the outside. 14b. The steam inlet 14 a communicates with the steam port 12 b of the inner lid 12. The steam generated in the pan-like container 5 passes through the steam port 12b, enters the cartridge 14 through the steam inlet 14a, flows through the cartridge 14, and flows out from the steam outlet 14b. Since the steam is cooled and condensed in the process of flowing through the cartridge 14, the amount of steam flowing out of the rice cooker 100 can be reduced.

  The operation display unit 15 provided on the upper surface of the outer lid 11 receives an operation input by a user (operator) and displays information related to the operation input and information indicating the state of the rice cooker 100. Items that can be set using the operation display unit 15 include, for example, start and cancellation of rice cooking, rice cooking reservation, and rice cooking menu. Items displayed by the operation display unit 15 include, for example, the state of the rice cooker 100 during cooking or waiting for reservation, the contents of the set rice cooking menu, the scheduled cooking time, the current time, and the amount of rice to be cooked Etc.

  The main body 1 further includes a control unit 8 and a time measurement unit 7. The detected temperature information from the pan bottom temperature sensor 4 and the internal temperature sensor 16 and the user operation information from the operation display unit 15 are input to the control unit 8. Based on these input information, the control part 8 performs a rice cooking process according to a rice cooking program, and performs control which flows a high frequency current through the heating coil 3. FIG.

  The control unit 8 may be configured by hardware such as a circuit device, or may be configured by an arithmetic device such as a microcontroller or CPU (Central Processing Unit) and software executed thereon. Good.

  The time measuring unit 7 counts the elapsed time based on the instruction signal from the control unit 8. The elapsed time counted by the time measuring unit 7 is output to the control unit 8.

  Next, the structure of the pan-like container 5 will be described with reference to FIG. 2A and 2B are a cross-sectional view and a plan view showing the configuration of the pan-like container 5 of the first embodiment. As described above, the pot-like container 5 is made of a magnetic material that generates heat by induction heating.

  As shown in FIG. 2 (A), the pot-shaped container 5 includes a disc-shaped bottom 51, a cylindrical peripheral wall 52 extending along the periphery of the bottom 51, and an opening facing the bottom 51. A bottomed cylindrical member having A flange portion 53 is provided along the outer periphery of the upper end portion of the peripheral wall portion 52. In the first embodiment, the inner surface of the bottom 51 is a flat surface having no irregularities.

  The central axis (indicated by reference numeral C) of the cylindrical peripheral wall portion 52 is the central axis of the pan-like container 5. The radial direction of the peripheral wall portion 52 is referred to as “radial direction”. In the pot-like container 5, the side close to the peripheral wall portion 52 is referred to as “outer peripheral side”, and the side close to the central axis C is referred to as “central side”. Further, the inner surface, that is, the upper surface of the bottom 51 is referred to as a “bottom surface”.

  A central region (region located in the radial center) of the inner surface of the bottom 51 is defined as a bottom central portion 51a. Moreover, the area | region of the outer peripheral side of the bottom face center part 51a in the inner surface of the bottom part 51 is made into the bottom face outer peripheral part 51b. The bottom surface outer peripheral portion 51b is a ring-shaped region surrounding the bottom surface central portion 51a.

  A coating film 50 (coating film) is provided on the inner surface of the pan-like container 5. The coating film 50 includes a coating film center part 50a (first surface part: first coating film part) provided on the bottom surface center part 51a of the bottom part 51 and a coating film outer periphery part 50b provided on the bottom surface outer periphery part 51b. (Second surface portion: second coating film portion) and a coating film side surface portion 50 d provided on the inner surface of the peripheral wall portion 52.

  As shown in FIG. 2B, the coating film center portion 50a is formed in a circular shape centered on the central axis C. The coating film outer peripheral part 50b is formed in the ring shape surrounding the coating-film center part 50a. Moreover, the coating-film side part 50d is formed in the ring shape surrounding the coating-film outer peripheral part 50b.

  In addition, the coating-film side part 50d does not need to reach the upper end of the surrounding wall part 52, and should just be provided in the area | region which contacts the to-be-heated material among the inner surfaces of the surrounding wall part 52.

  In the first embodiment, the coating film 50 on the inner surface of the pan-like container 5 has a hydrophilicity of the coating film outer peripheral part 50b higher than the hydrophilicity of the coating film central part 50a, and the hydrophilicity of the coating film outer peripheral part 50b. Is formed to be higher than the hydrophilicity of the bottom 51d. Thus, by making hydrophilicity different, the bubble which is small toward the outer peripheral side of the pan-like container 5 is generated, and the effect of reducing the bubbles rising along the peripheral wall portion 52 (side surface) is achieved. Hereinafter, this principle will be described.

  First, an example in which a water-repellent coating film (that is, a coating film having low hydrophilicity) 501 is provided on the inner surface of the pan-like container 5 will be described as a comparative example for the first embodiment. FIG. 3A is a cross-sectional view schematically showing the state of generation of bubbles when a water-repellent coating film is provided on the inner surface of the pan-like container 5. FIG. 3B is a cross-sectional view schematically showing the shape of the cooked surface. Here, for convenience of explanation, the same reference numerals as those used in Embodiment 1 are used for explanation.

  The water-repellent coating film refers to, for example, a coating film having a contact angle with water of 90 ° to 110 °. Here, the water-repellent coating film 501 is formed by coating the inner surface of the pan-like container 5 with a fluorine resin.

  The water-repellent coating film (coating film having low hydrophilicity) 501 repels water, and the rice 200 is less sticky. Therefore, there exists an advantage that it is easy to wash | clean the pot-shaped container 5 and cleaning property is good. On the other hand, the water-repellent coating film 501 has high air bubble adhesion.

  In the rice cooker 100, the pan-like container 5 is heated by passing a high-frequency current through the heating coil 3 (FIG. 1). Therefore, the bottom 51 facing the heating coil 3 is heated to the highest temperature. When the bottom 51 is heated, water contained in the heated object in the pan-like container 5 evaporates, and bubbles (also referred to as boiling bubbles) are generated.

  As described above, the water-repellent coating film 501 has high air bubble adhesion. Therefore, of the bubbles generated at the bottom 51, only the bubbles that grow to a size that exceeds the buoyancy of the adhesion to the coating film 501 are detached from the coating film 501. Therefore, the bubble size increases.

  Further, when the bubble grows while being in contact with the coating film 501, when the bubble moves from the bottom 51 to the peripheral wall portion 52, the bubble rises while being in contact with the coating film 501 of the peripheral wall portion 52.

  That is, when the water-repellent coating film 501 is provided on the inner surface of the pan-like container 5, as shown in FIG. 3 (A), the size of the bubbles increases and the bubbles rise along the peripheral wall portion 52 (side surface). The ratio of increases.

  Thus, when there are many bubbles rising along the peripheral wall portion 52, the number of bubbles passing through the object to be heated (rice 200 and water 201) decreases, and as a result, sufficient heat is not transmitted to the entire object to be heated. , Cooking unevenness occurs.

  Moreover, since bubbles tend to concentrate on the peripheral wall portion 52 side, the cooked surface has a shape with a depressed center as shown in FIG. That is, a boiled surface (a shape reminiscent of plump taste) is not formed.

  Next, an example in which a hydrophilic coating film 502 is provided on the inner surface of the pan-like container 5 will be described as another comparative example. FIG. 4A is a cross-sectional view schematically showing the state of generation of bubbles when a hydrophilic coating film 502 is provided on the inner surface of the pan-like container 5. FIG. 4B is a cross-sectional view schematically showing the shape of the cooked surface.

  The hydrophilic coating film refers to a coating film having a contact angle with water of less than 90 °, for example. Here, the hydrophilic coating film 502 is formed by coating the inner surface of the pan-like container 5 with a hydrophilic material.

  The hydrophilic coating 502 has low bubble adhesion. Therefore, bubbles generated by boiling at the bottom 51 of the pan-like container 5 are detached from the coating film 502 before they grow large. Therefore, the bubble size is reduced. On the other hand, the number of bubbles rising along the peripheral wall portion 52 is small due to low adhesion to the coating film 502.

  That is, when the hydrophilic coating film 502 is provided on the inner surface of the pan-like container 5, small bubbles are uniformly generated from the entire bottom 51 as shown in FIG. In this case, compared with the case where the water-repellent coating film 501 is provided (FIG. 3), the number of bubbles passing through the object to be heated increases, so that the cooking unevenness is reduced.

  On the other hand, the hydrophilic coating film 502 is likely to stick to the rice 200 and has low cleaning properties. In addition, since small bubbles are uniformly generated from the entire bottom portion 51, the boiled surface has a flat shape as shown in FIG. A flat boiled surface is more desirable than a boiled surface with a depressed center (FIG. 3), but it is not a shape reminiscent of plump and delicious like a mountain shape.

  In the first embodiment, in consideration of the characteristics of the water-repellent coating film and the hydrophilic coating film described with reference to FIG. 3 and FIG. It is possible to obtain a surface after cooking and further improve the cleanability of the pan-like container 5.

  FIG. 5A is a cross-sectional view schematically showing the state of generation of bubbles in the pan-like container 5 of the first embodiment. FIG. 5B is a cross-sectional view schematically showing the shape of the cooked surface. As described above, in the first embodiment, the hydrophilicity of the coating film outer peripheral portion 50b is higher than the hydrophilicity of the coating film central portion 50a, and the hydrophilicity of the coating film outer peripheral portion 50b is higher than the hydrophilicity of the coating film side surface portion 50d. Is also expensive.

  In other words, the coating film center part 50a and the coating film side part 50d have higher water repellency than the coating film outer peripheral part 50b (that is, the adhesiveness of bubbles is high).

  In a particularly desirable example, the coating film center part 50a is water-repellent, the coating film outer peripheral part 50b is hydrophilic, and the coating film side part 50d is water-repellent. In other words, the contact angle with respect to water of the coating film central portion 50a is 90 ° or more (more desirably 90 ° or more and 110 ° or less), and the contact angle with respect to water of the coating film outer peripheral portion 50b is less than 90 ° (more desirably). 5 ° or more and less than 90 °), and the contact angle of the coating film side surface portion 50d with water is desirably 90 ° or more (more desirably 90 ° or more and 110 ° or less).

  Such a configuration of the coating film 50 can be realized, for example, by coating the entire inner surface of the pan-like container 5 with a water-repellent fluororesin and then irradiating the coating film outer peripheral portion 50b with ultraviolet rays. This is because the surface of the fluororesin having water repellency is modified by being irradiated with ultraviolet rays to become hydrophilic. The longer the ultraviolet irradiation time and the shorter the wavelength, the smaller the contact angle (that is, the higher the hydrophilicity).

  The fluororesin having water repellency is, for example, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) or PTTF (polytetrafluoroethylene).

  Further, after coating the entire inner surface of the pan-like container 5 with a fluororesin having water repellency, it may be made hydrophilic by roughening the surface roughness of the coating film outer peripheral portion 50b instead of ultraviolet irradiation. Or you may form the coating-film outer peripheral part 50b by coating materials other than a fluororesin.

  The central portion 50a of the coating film has water repellency (that is, low hydrophilicity), and thus has high bubble adhesion. For this reason, bubbles generated in the coating film central portion 50a grow into large bubbles and are detached from the coating film central portion 50a. That is, the bubble size is large.

  When bubbles generated in the coating film central portion 50a move to the outer peripheral side, the coating film outer periphery portion 50b has low air bubble adhesion, and therefore, the bubbles are detached at the boundary portion between the coating film central portion 50a and the coating film outer periphery portion 50b. .

  On the other hand, the coating film outer peripheral portion 50b has high hydrophilicity, and therefore has low bubble adhesion. For this reason, the bubbles generated at the coating film outer peripheral part 50b are detached from the coating film outer peripheral part 50b before they grow large. That is, the bubble size is small.

  Since the bubbles generated at the coating film outer peripheral portion 50b are immediately detached, there are few bubbles moving to the coating film central portion 50a and the coating film side surface portion 50d.

  The side surface portion 50d of the coating film has water repellency (that is, low hydrophilicity), and therefore has high air bubble adhesion. Therefore, the bubbles generated at the coating film side surface portion 50d grow into large bubbles and are detached from the coating film side surface portion 50d. That is, the bubble size is large.

  However, the coating film side surface portion 50d provided on the peripheral wall portion 52 is farther away from the heating coil 3 (FIG. 1) than the coating film center portion 50a and the coating film outer periphery portion 50b provided on the bottom portion 51, and thus has a low temperature. Therefore, there are few bubbles generated at the side surface portion 50d of the coating film.

  Further, as described above, since bubbles in the coating film outer peripheral portion 50b are generated and immediately detached, there are few bubbles moving from the coating film outer peripheral portion 50b to the coating film side surface portion 50d. Accordingly, there are bubbles rising along the side surface portion 50d of the coating film, but the amount thereof is small.

  Thus, large bubbles are generated at the coating film center portion 50a, small bubbles are generated at the coating film outer peripheral portion 50b, and a small amount of large bubbles are generated at the coating film side surface portion 50d. And even if the bubble which generate | occur | produced in the coating-film center part 50a moves to an outer peripheral side, it detach | leaves in the boundary part of the coating-film center part 50a and the coating-film outer peripheral part 50b. Further, since the bubbles generated at the coating film outer peripheral portion 50b are immediately released, there are few bubbles reaching the coating film side surface portion 50d.

  Thus, many of the bubbles generated at the coating film central part 50a and the coating film outer peripheral part 50b do not reach the coating film side part 50d. For this reason, the amount of bubbles rising along the peripheral wall portion 52 (coating side surface portion 50d) is very small, and the outer peripheral portion of the cooked surface is difficult to rise. Further, the amount of bubbles rising in the region (the inner region) away from the peripheral wall portion 52 increases. Therefore, a mountain-like cooked surface with a raised central part is obtained.

  Moreover, since there are few air bubbles rising along the surrounding wall part 52 (coating-film side part 50d), many air bubbles pass in a to-be-heated material. Therefore, convection of the object to be heated can be promoted and heat can be efficiently transferred to the object to be heated.

  Moreover, since the coating film center part 50a and the coating film side part 50d have water repellency, there is little sticking of rice in the coating film center part 50a and the coating film side part 50d. Therefore, it is easy to wash the pan-like container 5 and the cleanability is good.

  As described above, in the first embodiment of the present invention, a plurality of coating film parts (coating film center part 50a and coating film outer peripheral part 50b) having different hydrophilicity are provided on the inner surface of the bottom part 51, and the outer peripheral side. The hydrophilicity of the coating film outer peripheral part 50b is higher than the hydrophilicity of the coating film center part 50a. Therefore, the amount of bubbles rising along the peripheral wall portion 52 can be reduced, and the cooked surface can be formed into a mountain shape with a raised central portion. Moreover, the convection effect of a to-be-heated material can be improved and a to-be-heated material can be heated efficiently. Furthermore, since the coating film center portion 50a has low hydrophilicity (desirably, it has water repellency), it is possible to suppress sticking of rice and improve cleaning properties.

  In addition, by providing the peripheral wall portion 52 of the pan-like container 5 with a coating film side surface portion 50d having a lower hydrophilicity (desirably having water repellency) than the first coating film portion (coating outer peripheral portion 50b), Further, the cleaning property can be improved.

  Moreover, since the coating film center part 50a is circularly formed in the center part of the bottom part 51, and the coating film outer peripheral part 50b is formed in the ring shape so that the coating film center part 50a may be enclosed, the whole to-be-heated material is efficient. Can be heated well.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 6 (A) is a cross-sectional view showing the configuration of the pan-like container 5A of Embodiment 2 together with the state of generation of bubbles. FIG. 6B is a cross-sectional view schematically showing the shape of the cooked surface in the second embodiment.

  In the first embodiment described above, the bottom 51 of the pan-like container 5 is provided with the coating film central part 50a and the coating film outer peripheral part 50b having different hydrophilicity. In this second embodiment, FIG. As shown, in addition to the coating film center part 50a and the coating film outer peripheral part 50b, a coating film intermediate part 50c is provided on the bottom 51 of the pan-like container 5A. The coating film side surface portion 50d of the peripheral wall portion 52 is the same as that in the first embodiment.

  The coating film intermediate part 50 c is arranged between the coating film center part 50 a and the coating film outer peripheral part 50 b in the radial direction of the bottom part 51. That is, the coating film intermediate portion 50 c is formed in the bottom surface intermediate portion 51 c between the bottom surface central portion 51 a of the bottom portion 51 and the bottom surface outer peripheral portion 51 b. In other words, the coating film intermediate portion 50c is disposed on the outer peripheral side of the coating film central portion 50a and on the central side of the coating film outer peripheral portion 50b, and extends in a ring shape.

  The coating film intermediate part 50c has higher hydrophilicity than the coating film center part 50a and lower hydrophilicity than the coating film outer peripheral part 50b. That is, the hydrophilicity is high in the order of the coating film center part 50a, the coating film intermediate part 50c, and the coating film outer periphery part 50b (that is, from the center part to the outer periphery part of the bottom 51).

  The coating film 50 is configured, for example, by coating the entire inner surface of the pan-like container 5A with a water-repellent fluororesin and then irradiating the coating film intermediate part 50c and the coating film outer peripheral part 50b with ultraviolet rays. This can be realized by making the irradiation time of the coating film outer peripheral portion 50b longer (or shortening the wavelength) than the intermediate portion 50c.

  Since it is comprised as mentioned above, the adhesiveness of the bubble in the coating-film intermediate part 50c is lower than the coating-film center part 50a, and higher than the coating-film outer peripheral part 50b. For this reason, the bubbles generated in the coating film middle portion 50c are smaller than the bubbles generated in the coating film center portion 50a and larger than the bubbles generated in the coating film outer peripheral portion 50b. That is, the bubble is the largest at the central portion of the bottom 51 and becomes smaller toward the outer peripheral side.

  Further, when the bubbles generated in the coating film central part 50a and the coating film intermediate part 50c move to the outer peripheral side, the coating film outer peripheral part 50b has low adhesiveness of the bubbles, so the coating film intermediate part 50c and the coating film outer peripheral part 50b Air bubbles break off at the boundary. In addition, since the bubbles generated at the coating film outer peripheral portion 50b are detached from the coating film outer periphery portion 50b before they grow large, only a few bubbles reach the coating film side surface portion 50d.

  Similarly to the first embodiment, the coating film side surface portion 50d provided on the peripheral wall portion 52 has a heating coil 3 (FIG. 1) rather than the coating film center portion 50a, the coating film intermediate portion 50c, and the coating film outer periphery portion 50b. Since the distance is far from, there are few bubbles generated at the side surface portion 50d of the coating film. Therefore, as in the first embodiment, there are bubbles rising along the coating film side surface portion 50d, but the amount thereof is small.

  Thus, since there are few bubbles which raise along the coating-film side part 50d, the outer peripheral part of a boiled surface is hard to rise. Further, the amount of bubbles rising in the region (the inner region) away from the peripheral wall portion 52 increases. Therefore, a mountain-like cooked surface with a raised central part is obtained.

  In addition, since the size of the bubbles becomes smaller in the order of the coating film center part 50a, the coating film intermediate part 50c, and the coating film outer peripheral part 50b, the center part of the cooked surface is raised to the highest level, and the surroundings are raised slightly higher, The shape of the cooked surface can be made smoother.

  5A of pot-like containers of Embodiment 2 are the same as the pot-like container 5 of Embodiment 1 except having provided the coating-film intermediate part 50c between the coating-film center part 50a and the coating-film outer peripheral part 50b. Composed. Moreover, the rice cooker of Embodiment 2 is comprised similarly to the rice cooker 100 of Embodiment 1 except the structure of 5 A of pot-shaped containers.

  As described above, in Embodiment 2 of the present invention, the bottom 51 is provided with three or more coating film parts (coating film center part 50a, coating film middle part 50c, and coating film outer peripheral part 50b) having different hydrophilicity. The hydrophilicity increases from the center side of the bottom 51 to the outer peripheral side. Therefore, in addition to the effect demonstrated in Embodiment 1, the shape of the cooked surface can be made smoother.

  In addition, in Embodiment 2, although the case where three coating-film parts with different hydrophilicity were provided in the bottom part 51 was demonstrated, four or more coating-film parts are provided, and hydrophilicity is provided from the center side of the bottom part 51 to the outer peripheral side. You may comprise so that it may become high. Thereby, it becomes possible to finely control the size and generation position of the bubbles, and to smooth the shape of the cooked surface.

  In such a configuration, for example, after coating the entire inner surface of the pan-like container 5 with a water-repellent fluororesin, the above-described ultraviolet irradiation is performed, and the ultraviolet irradiation time is increased toward the outer peripheral side of the bottom 51 (or the wavelength). Can be realized.

  Moreover, as shown in FIG.6 (C), you may comprise the coating film 50 of the bottom part 51 so that hydrophilicity may become high continuously from the center part of the bottom part 51 to an outer peripheral part. Thereby, it becomes possible to finely control the size and generation position of the bubbles, and to smooth the shape of the cooked surface.

  In such a configuration, for example, after coating the entire inner surface of the pan-like container 5 with a water-repellent fluororesin, the above-described ultraviolet irradiation is performed, and irradiation is performed so that the ultraviolet irradiation time becomes longer toward the outer peripheral side of the bottom 51. This can be realized by changing the time continuously (or changing the wavelength continuously so that the wavelength becomes shorter toward the outer peripheral side of the bottom 51).

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. FIG. 7A is a cross-sectional view showing the configuration of the pan-like container 5B according to Embodiment 3 together with the state of generation of bubbles. FIG. 7B is a plan view showing the configuration of the pan-like container 5B of the third embodiment. FIG. 8 is a cross-sectional view schematically showing the shape of the cooked surface in the third embodiment.

  In the first embodiment described above, the inner surface of the bottom 51 is a flat surface. However, in the third embodiment, the bottom 51 is provided with the recesses 17a and 17b. Specifically, a concave portion 17a (first concave portion) is provided in the bottom surface central portion 51a of the bottom portion 51, and a concave portion 17b (second concave portion) is provided in the bottom surface outer peripheral portion 51b. The recesses 17a and 17b are both circular when viewed from above.

  The inner diameters of the recesses 17a and the recesses 17b are determined according to the size of bubbles generated in the coating film central part 50a and the coating film outer peripheral part 50b (that is, the level of hydrophilicity). The inner diameter of the recess 17a is equal to or greater than (more preferably the same) the average size of the bubbles generated in the coating film central portion 50a. The inner diameter of the recess 17b is equal to or greater than (more preferably, the same) the average size of bubbles generated in the coating film outer peripheral portion 50b.

  In addition, when the coating film center part 50a is water-repellent (contact angle 90 ° or more), the average size of bubbles generated in the coating film center part 50a is, for example, about 10 mm. Moreover, when the coating film outer peripheral part 50b is made hydrophilic with a contact angle of 5 to 10 °, the average size of bubbles generated in the coating film outer peripheral part 50b is, for example, about 3 mm.

  As described in the first embodiment, the coating film central portion 50a is lower in hydrophilicity than the coating film outer peripheral portion 50b, and thus has high air bubble adhesion. It is larger than the bubble generated in the part 50b. Accordingly, the inner diameter of the recess 17a is larger than the inner diameter of the recess 17b.

  Here, as shown in FIG. 7B, one concave portion 17a is arranged at the center of the bottom surface central portion 51a of the bottom portion 51, and six concave portions 17a are arranged at equal intervals in the circumferential direction so as to surround one of them. Has been. In addition, in the bottom surface outer peripheral portion 51b of the bottom portion 51, twelve rows of recesses 17b arranged in a row are arranged radially.

  However, the shape, arrangement and number of the recesses 17a and 17b are not limited to the example shown in FIG. 7B, and can be changed as appropriate.

  The recesses 17a and 17b serve as boiling nuclei. When the boiling nuclei are formed, bubbles are continuously generated from the portions, and as shown in FIG. 8, a steam passage called a crab hole is generated in the object to be heated. Crab holes play a role in spreading steam throughout the object to be heated, and are also known as a sign of deliciousness. The recesses 17a and 17b serve as boiling nuclei and form crab holes, so that cooked rice can be cooked.

  When the inner diameters of the recesses 17a and 17b are smaller than the average bubble size, the recesses 17a and 17b are buried in the bubbles and do not serve as boiling nuclei. Preferably the same).

  The pot-like container 5B according to the third embodiment is configured in the same manner as the pot-like container 5 according to the first embodiment, except that the bottom portion 51 is provided with the recesses 17a and 17b. However, the coating film central part 50a is also formed on the inner peripheral surface of the recess 17a, and the coating film outer peripheral part 50b is also formed on the inner peripheral surface of the recess 17b. Moreover, the rice cooker of Embodiment 3 is comprised similarly to the rice cooker 100 of Embodiment 1 except the structure of the pan-shaped container 5B.

  Here, the concave portion 17a is provided in the bottom surface central portion 51a of the bottom portion 51, and the concave portion 17b is provided in the bottom surface outer peripheral portion 51b. However, even if the concave portion is provided in only one of the bottom surface central portion 51a and the bottom surface outer peripheral portion 51b, The effect of suppressing uneven cooking due to the formation of crab holes is obtained.

  Moreover, although the recessed part 17a, 17b was provided in the bottom part 51 of the pan-like container 5 demonstrated in Embodiment 1 here, you may provide a recessed part in the bottom part 51 of the pan-shaped container 5A demonstrated in Embodiment 2. FIG. . In this case, for example, the inner diameter of the concave portion provided in each region of the bottom 51 (the region where the coating film central portion 50a, the coating film intermediate portion 50c, and the coating film outer peripheral portion 50b are provided) is set to the average size of bubbles generated in each region. Can be determined accordingly.

  As described above, in Embodiment 3 of the present invention, the bottom 51 is provided with the recesses 17a and 17b having an inner diameter equal to or larger than the average bubble size, so that the recesses 17a and 17b serve as boiling nuclei. Crab holes can be formed in the object to be heated. Therefore, in addition to the effects described in the first embodiment, it is possible to cook rice without further uneven cooking.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described. FIG. 9A is a cross-sectional view showing the configuration of the pan-like container 5C of Embodiment 4 together with the state of bubbles generated. FIG. 9B is a plan view showing the configuration of the pan-like container 5C of the fourth embodiment. FIG. 10 is a cross-sectional view schematically showing the shape of the cooked surface in the fourth embodiment.

  In the fourth embodiment, the water-repellent coating film portion 18 is provided on the hydrophilic coating film outer periphery portion 50b provided on the bottom portion 51 (more specifically, the bottom surface outer periphery portion 51b). In addition, although the coating-film part 18 has water repellency here, the hydrophilicity should just be lower than the coating-film outer peripheral part 50b.

  Here, as shown in FIG. 9B, twelve circular coated film portions 18 are arranged at equal intervals in the circumferential direction of the bottom portion 51. However, the shape, arrangement, and number of the coating film portions 18 are not limited to the example shown in FIG. 9B, and can be changed as appropriate.

  In such a configuration, the coating film 50 is formed on the inner surface of the pan-like container 5C by the method described in Embodiment 1, and then a water-repellent coating material is applied in a circular shape to the coating film outer peripheral portion 50b. Can be realized.

  Since the water-repellent coating film portion 18 has a high adhesion force of bubbles, the bubbles are likely to become large, and when the bubbles move to the hydrophilic coating film outer periphery portion 50b, the adhesion force decreases, so that the bubbles are detached from the coating film outer periphery portion 50b. Then rise upwards. That is, large bubbles are continuously detached on the coating film portion 18.

  Thus, since the coating film part 18 plays the same role as the boiling nucleus, as shown in FIG. 10, a crab hole can be formed in the object to be heated, and the steam can be spread over the entire object to be heated. Thereby, the rice without cooking unevenness can be cooked.

  In order for the coating film portion 18 to serve as a boiling nucleus, the outer diameter of the coating film portion 18 is equal to or larger than the average bubble size generated on the coating film portion 18, that is, the average bubble size (more preferably, the same). It is desirable that

  The pot-like container 5C of the fourth embodiment is configured in the same manner as the pot-like container 5 of the first embodiment except that the water-repellent coating film portion 18 is provided on the hydrophilic coating film outer peripheral portion 50b. Is done. Moreover, the rice cooker of Embodiment 4 is comprised similarly to the rice cooker 100 of Embodiment 1 except the structure of 5 C of pot-shaped containers.

  Here, the water-repellent coating film portion 18 is provided on the coating film outer peripheral portion 50b of the pan-like container 5 described in the first embodiment, but the coating film outer peripheral portion of the pan-shaped container 5A described in the second embodiment. A water-repellent coating film portion 18 may be provided on 50b.

  As described above, in Embodiment 4 of the present invention, since the water-repellent coating film portion 18 is provided on the coating film outer peripheral portion 50b of the bottom 51, the coating film portion 18 serves as a boiling nucleus. Crab holes can be formed in the object to be heated. Therefore, in addition to the effect demonstrated in Embodiment 1, the rice without cooking unevenness can be cooked.

Embodiment 5. FIG.
Next, a fifth embodiment of the present invention will be described. FIG. 11A is a cross-sectional view showing a configuration of a pan-like container 5D of the fifth embodiment. FIG. 11B is a plan view showing the configuration of the pan-like container 5D of the fifth embodiment.

  In the first embodiment described above, the inner surface of the bottom 51 is a flat surface. However, in the fifth embodiment, the convex portion 19 that protrudes (protrudes) upward is provided at the radial center of the bottom 51. Yes.

  A flat surface 19 a that is a flat surface is formed at the center of the convex portion 19. As shown in FIG. 11B, the flat surface 19a is formed in a circular shape when viewed from above. On the outer peripheral side of the flat surface 19a, an inclined surface 19b having a height that decreases toward the outer side in the radial direction is formed. The inclined surface 19b is formed in a ring shape when viewed from above. On the outer peripheral side of the inclined surface 19b of the convex portion 19, a flat innermost lowermost portion 19c located at the lowermost position among the inner surfaces of the pan-like container 5D is formed. The innermost lowermost portion 19c is formed in a ring shape when viewed from above.

  The flat surface 19a of the convex portion 19 is provided with a coating film central portion 50a. A coating film outer peripheral portion 50b is provided from the inclined surface 19b of the convex portion 19 to the innermost lowermost portion 19c. The coating film outer peripheral part 50b is more hydrophilic than the coating film center part 50a. As described in the first embodiment, the peripheral wall portion 52 is provided with the coating film side surface portion 50d.

  The inclined surface 19 b of the convex portion 19 is located vertically above the heating coil 3. That is, the coating film outer peripheral portion 50 b provided on the inclined surface 19 b is located vertically above the heating coil 3. In the example shown in FIG. 11, the innermost lowermost portion 19 c is also located vertically above the heating coil 3, but at least the inclined surface 19 b only needs to be located vertically above the heating coil 3.

  At the time of heating by the heating coil 3, the portion (the portion indicated by the symbol A in FIG. 11B) located vertically above the heating coil 3 of the inner surface of the pan-like container 5D becomes the highest temperature. When bubbles are generated intensively in the high temperature part, the cooked surface is locally raised and a mountain shape may not be obtained.

  Therefore, in the fifth embodiment, the convex portion 19 is provided on the bottom portion 51 of the pan-like container 5D, and the inclined surface 19b is disposed vertically above the heating coil 3 (that is, the highest temperature portion).

  FIG. 12 is a diagram schematically illustrating the behavior of bubbles generated on the inclined surface 19 b of the convex portion 19. Since the coating surface outer peripheral portion 50b having high hydrophilicity is provided on the inclined surface 19b of the convex portion 19, the bubbles generated in this portion are detached from the coating film outer peripheral portion 50b before growing greatly.

  On the other hand, bubbles having such a size that the buoyancy does not exceed the adhesive force with the coating film outer peripheral part 50b rises along the coating film outer peripheral part 50b while being in contact with the coating film outer peripheral part 50b. That is, bubbles of such a size do not rise if the coating film outer peripheral part 50b is flat (horizontal), but rises along the inclination because the coating film outer peripheral part 50b is inclined. .

  Further, when the bubbles rising along the coating film outer peripheral portion 50b reach the coating film center portion 50a having low hydrophilicity (strong adhesion), the bubbles adhere to the coating film center portion 50a. Then, after the buoyancy grows to a size exceeding the adhesive force, the film detaches from the coating film central portion 50a.

  In this way, by providing the inclined surface 19b at the highest temperature portion of the bottom 51 and further providing the coating film outer peripheral portion 50b, a part of the bubbles generated at the highest temperature portion moves to the center along the inclined surface 19b. Can be made.

  That is, even when bubbles are intensively generated in a portion located vertically above the heating coil 3, it is caused by local heating of an object to be heated by moving some of the bubbles to the center. It is possible to obtain a mountain shape by suppressing cooking unevenness and suppressing local rise of the cooked surface.

  The pot-like container 5D of the fifth embodiment is configured in the same manner as the pot-like container 5 of the first embodiment except that the convex portion 19 is provided on the bottom 51. Moreover, the rice cooker of Embodiment 5 is comprised similarly to the rice cooker 100 of Embodiment 1 except the structure of 5D of pot-shaped containers.

  Here, although the convex part 19 was provided in the pot-shaped container 5 demonstrated in Embodiment 1, you may provide the convex part 19 in the pot-shaped container 5D demonstrated in Embodiment 2-4.

  As described above, in the fifth embodiment of the present invention, the convex portion 19 is provided at the bottom 51 of the pan-like container 5D, and the inclined surface 19b is provided at the portion heated to the highest temperature by the heating coil 3. Therefore, the bubbles generated at the high temperature portion of the bottom 51 can be moved to the center of the pan-like container 5D. Therefore, in addition to the effects described in the first embodiment, even when bubbles are intensively generated at the high temperature portion of the bottom portion 51, cooking unevenness is suppressed, and a mountain-shaped cooked surface whose center is raised Can be obtained.

  In each of the above-described embodiments, the coating film having different hydrophilicity is formed on the inner surface of the pan-like container 5, but instead of forming the coating film having different hydrophilicity, the surface roughness of the pot-like container 5 is changed. The hydrophilicity may be made different.

  FIG. 13 shows a bottom-like central portion 51a and a bottom-surface outer peripheral portion 51b of the bottom 51 instead of forming the coating-film central portion 50a, the coating-film outer peripheral portion 50b, and the coating-film side portion 50d in the pan-like container 5 of the first embodiment. And it is a figure which shows the pan-shaped container 5E which varied the surface roughness of the surrounding wall part 52. FIG.

  In general, the hydrophilicity increases as the surface roughness increases. Therefore, for example, by making the surface roughness of the bottom surface outer peripheral portion 51b (second surface portion) rougher than the surface roughness of the bottom surface central portion 51a (first surface portion), the hydrophilicity of the bottom surface outer peripheral portion 51b is changed to the bottom surface. The hydrophilicity of the central portion 51a can be made higher. Further, by making the surface roughness of the bottom surface outer peripheral portion 51 b larger than the surface roughness of the peripheral wall portion 52, the hydrophilicity of the bottom surface outer peripheral portion 51 b can be made higher than the hydrophilicity of the peripheral wall portion 52.

  Similarly, in Embodiments 2 to 5, it is possible to change the hydrophilicity by changing the surface roughness of the pan-like container 5 instead of forming a coating film having different hydrophilicity.

  The preferred embodiments of the present invention have been specifically described above. However, the present invention is not limited to the above-described embodiments, and various improvements or modifications are made without departing from the gist of the present invention. be able to.

  The present invention can be applied to, for example, commercial and household rice cookers (heating cookers) and containers thereof.

DESCRIPTION OF SYMBOLS 1 Main body (main body part), 2 Container cover, 3 Heating coil (heating part), 4 Pan bottom temperature sensor, 5, 5A, 5B, 5C, 5D, 5E Pan-shaped container, 6 Hinge part, 7 time measurement part, 8 Control Part, 9 lid packing, 10 lid body, 11 outer lid, 12 inner lid, 13 locking material, 14 cartridge, 15 operation display part, 16 internal temperature sensor, 17a, 17b concave part, 18 coating area, 19 convex part, 19a plane, 19b inclined surface, 50 coating film, 50a coating film central part (first surface part), 50b coating film outer peripheral part (second surface part), 50c coating film middle part (third surface part), 50d Coating side surface portion, 51 bottom portion, 51a bottom surface central portion, 51b bottom surface outer periphery portion, 51c bottom surface intermediate portion, 52 peripheral wall portion, 53 flange portion, 200 rice, 201 water.

Claims (14)

A container having a bottom and a peripheral wall provided on the outer periphery of the bottom;
A main body for housing the container;
A heating unit for heating the container,
The inner surface of the bottom portion is provided with a plurality of surface portions having different hydrophilicity,
The plurality of surface portions include a first surface portion and a second surface portion that is disposed on the outer peripheral side of the first surface portion and has higher hydrophilicity than the first surface portion. Rice cooker characterized by. 2. The rice cooker according to claim 1, wherein the plurality of surface portions of the bottom portion are configured by a plurality of coating portions having different hydrophilicity provided on the bottom portion.   The rice cooker according to claim 1, wherein the plurality of surface portions of the bottom portion are configured by portions having different surface roughnesses formed on the bottom portion.   The rice cooker according to any one of claims 1 to 3, wherein the inner surface of the peripheral wall portion is less hydrophilic than the second surface portion. The first surface portion of the bottom portion is provided in a central portion of the bottom portion,
The rice cooker according to any one of claims 1 to 4, wherein the second surface portion of the bottom portion is provided so as to surround the first surface portion. The first surface portion of the bottom portion has a contact angle with water of 90 ° or more,
The rice cooker according to any one of claims 1 to 5, wherein the second surface portion of the bottom portion has a contact angle with water of less than 90 °. The first surface portion of the bottom portion has a contact angle with water of 90 ° or more and 110 ° or less,
The rice cooker according to claim 6, wherein the second surface portion of the bottom portion has a contact angle with water of 5 ° or more and less than 90 °.   The plurality of surface portions of the bottom portion are more hydrophilic than the first surface portion and more hydrophilic than the second surface portion between the first surface portion and the second surface portion. It has at least one surface part with low property, The rice cooker in any one of Claim 1-7 characterized by the above-mentioned.   9. The plurality of surface portions of the bottom portion are configured so that hydrophilicity continuously increases as the outer periphery of the bottom portion is approached. Rice cooker. The bottom portion includes a plurality of first recesses provided in the first surface portion, and a plurality of second recesses provided in the second surface portion,
The inner diameter of the first recess is equal to or larger than the average diameter of bubbles generated in the first surface portion by heating of the heating portion,
The internal diameter of the said 2nd recessed part is more than the average diameter of the bubble generate | occur | produced in the said 2nd surface part by the heating of the said heating part. The any one of Claim 1-9 characterized by the above-mentioned. rice cooker.   The coating film region having a lower hydrophilicity than the surface portion is provided on at least one surface portion of the plurality of surface portions of the bottom portion. Rice cooker according to item. The bottom portion includes a convex portion having an inclined surface,
The said inclined surface is arrange | positioned in the part heated to the highest temperature by the said heating part among the said bottom parts, The rice cooker in any one of Claim 1-11 characterized by the above-mentioned.   The rice cooker according to claim 12, wherein the second surface portion of the bottom portion is provided on the inclined surface. The bottom,
A peripheral wall provided on the outer periphery of the bottom,
The inner surface of the bottom portion is provided with a plurality of surface portions having different hydrophilicity,
The plurality of surface portions include a first surface portion and a second surface portion that is disposed on the outer peripheral side of the first surface portion and has higher hydrophilicity than the first surface portion. A container characterized by.

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