JP2007229214A5 - - Google Patents

Description

rice cooker

  The present invention relates to a rice cooker used for general household and business use.

Conventionally, in rice cookers that are widely available to the general public, a heating plate is installed so as to cover the pan in a removable manner with respect to the lid, and heating means for heating this heating plate appropriately is disposed inside the lid of the rice cooker Has been.

  The heating plate heated by the heating means in the lid has a function of transferring the heat to the rice and evaporating excess water adhering to the surface of the heating plate.

  The material usually used as the material for the heating plate is aluminum or austenitic stainless steel, but ferritic stainless steel is widely used in rice cookers with the function of heating the heating plate by electromagnetic induction from the viewpoint of improving the heat generation efficiency. It has been.

  Since the heating plate is a component that is placed relative to the pan during cooking of rice, the rice balls are likely to adhere, and the cooked rice is stuck with substances that tend to promote metal corrosion such as seasonings. In many cases, the lid is detachably attached to the lid to facilitate cleaning.

  For this reason, there is a case where a non-adhesive coat such as a fluororesin coat is processed on the metal material constituting the heating plate in order to facilitate cleaning (see, for example, Patent Document 1).

As a conventional example, after a metal base material such as aluminum is formed into a heating plate shape, the base material is subjected to a fluororesin coating treatment. In addition, a secondary effect of providing a good heating effect by far infrared rays emitted from the fluororesin coat was also brought about.
Japanese Patent No. 3515313

  As described above, conventionally, there are known examples in which a fluororesin coat is treated on a heating plate to improve the heating effect and the non-adhesive effect by far infrared rays emitted from the fluororesin coat.

  However, the fluororesin coating is originally a process with high water repellency, and when the hot resin coating is applied to the heating plate, the attached water droplets become enormous due to the high water repellency. Drops of water fall on the rice and cause it to burn, which can adversely affect the taste.

  In addition, when the temperature of the heating plate is increased to evaporate the water droplets in order to prevent the water droplets from dropping, the upper layer rice in the pan is yellowed by the radiant heat from the heating plate. It may adversely affect the outcome.

  In addition, in the case of a heating plate that can be attached and detached freely from the lid, it is often made of highly wearable material such as nylon scrubbing to remove dirt when the heating plate is washed after cooking. The surface of the coating may be rubbed, resulting in premature wear of the fluororesin coat, non-adhesive performance and appearance, and corrosion of the exposed substrate, or a decrease in far-infrared emissivity In some cases, the cooking result may be adversely affected.

  In recent years, especially in the electromagnetic induction heating type rice cooker, not only the main body but also the lid has an electromagnetic induction heating coil, and the heating plate itself is heated with high heating power by electromagnetic induction to obtain a better cooking result. Things that have been devised have also become common.

  In this case, there is an advantage that a non-adhesive effect can be obtained if both sides of the heating plate are treated with a fluororesin coating, but in some cases, heat conduction from the heating plate to the lid is caused by radiation of far infrared rays from the fluororesin coating. As a result of excessive heat absorption in the lid, the temperature of the members constituting the lid rises, which may adversely affect the deformation of the members and the electrical components housed in the lid, It cannot be said that the situation is favorable in terms of energy efficiency.

  For this reason, in the present invention, the coating to be processed on the surface of the heating plate facing the pan has an appropriate water repellency in a range that does not adversely affect the quality of the rice, has high durability against abrasion, and It is also an object to reduce far infrared rays absorbed by the lid while far infrared rays emitted from the heating plate sometimes concentrate on the rice side.

  In order to solve the above-mentioned conventional problems, the heating plate provided in the rice cooker of the present invention is detachably attached to an openable / closable lid, and the surface facing the pan is treated with a coating, and the top coat of the coating The surface of the substrate is controlled to have a water contact angle of 80 to 100 °, and the surface facing the lid of the heating plate has a surface finish with a far-infrared emissivity of 10% or less at a wavelength of 3 to 15 μm. If necessary, the top coat of the coating contains not less than 0.3 wt% and not more than 5 wt% of diamond particles.

  As a result, the coating processed on the surface facing the pan of the heating plate can be used to cook rice or to prevent water droplets from falling on the rice in the pan during heat insulation, and far infrared rays generated on the heating plate are The far-infrared radiation from the surface facing the lid is relatively low, so the heat absorbed by the lid is kept low, and the durability of the non-stick coating is high A rice cooker equipped with a heating plate can be provided.

  Furthermore, the heat absorbed by the lid can be further reduced by applying the heat reflecting coating on the surface of the lid facing the heating plate.

  Since the heating plate provided in the rice cooker of the present invention is processing a coating having an appropriate contact angle with respect to water, a large water droplet does not adhere to the coating, and the water droplet falls on the rice in the pan. It is possible to prevent the whitening of the rice, and it is not necessary to generate extra heating power on the heating plate to evaporate the large water droplets that are likely to occur when using a highly water-repellent coating such as a fluorine coating. Since heat can be efficiently added to rice, good cooking results can be obtained.

  1st invention is a rice cooker which has a main body, the pan detachably accommodated in the main body, a lid body that can be opened and closed, and a metal heating plate that is detachably attached to the lid body. Of both surfaces, the surface facing the pan is coated, the surface of the coating is controlled to have a water contact angle of 80 to 100 °, and the surface facing the lid of the heating plate has a wavelength of 3 to 15 μm. It is the rice cooker which has a heating plate characterized by being the surface finish whose far-infrared emissivity in 10% or less.

  When the heating plate is heated by the coating processed on the surface opposite to the pan of the heating plate, good radiant heat is radiated to the cooked food and has a positive effect on the cooking result of the rice. At this time, the contact angle of the coating surface with water Is preferably 80 to 100 °.

When the water contact angle is 100 ° or more, the water repellency is high and the non-adhesiveness is high, but the moisture adhering to the heating plate during cooking or heat retention tends to be spherical due to its surface tension.
This develops into large drops of water that occasionally fall into the cooked food.

  When a large drop of water falls on a cooked food, it partially burns or turns white, which not only adversely affects the taste but also makes the rice look deficient in appearance.

  Therefore, if a coating with high water repellency is used, it is necessary to evaporate the water droplets by heating the heating plate excessively so that no large water droplets are generated during cooking or heat insulation if it is desired to prevent dullness or whitening. However, excessive overheating increases the radiation from the heating plate to the food more than necessary, so it is easy to promote yellowing and deterioration of the rice.

  On the other hand, the lower the contact angle of water on the surface of the heating plate, the worse the non-adhesiveness, and the easier it is for the food to adhere to it.

  In this embodiment, by keeping the contact angle of water at 80 to 100 °, it is possible to prevent the adhering water from becoming large droplets while maintaining non-stickiness. It is difficult to fall down on objects, and whitishness and whitening can be suppressed, and it is not necessary to heat the heating plate excessively to evaporate water droplets, so that it is possible to prevent yellowing and deterioration of rice.

  The surface of the heating plate facing the lid is a rice cooker having a heating plate characterized in that the far-infrared emissivity at a wavelength of 3 to 15 μm is a surface finish of 10% or less, more specifically stainless steel. And those having high far-infrared reflectivity and low emissivity, such as mirror polishing finish, bright annealing finish, electrolytic polishing finish, and chemical polishing finish.

  Thereby, while the heat generated in the heating plate is efficiently transmitted to the cooked product side, excessive heat is radiated to the lid side and the temperature of the lid body can be prevented from excessively rising.

Furthermore , it is a rice cooker characterized in that a heat reflecting coating is provided on the surface of the lid facing the heating plate to provide a heat reflecting layer.

  By applying a heat-reflective coating to the surface of the lid facing the heating plate, the heat radiated from the heating plate is prevented from being absorbed into the lid, and unnecessary heating of the lid can be prevented. It has the effect of suppressing deterioration of parts and the like and deformation with time of resin parts.

  As the heat reflecting paint, a type including hollow ceramic beads, aluminum flakes, stainless steel flakes and the like is selected.

  According to a second aspect of the present invention, the top coat of the coating to be processed on the surface of the metal heating plate facing the pan is formed by applying a paint mainly composed of polyethersulfone to which a fluoro resin is added. It is a rice cooker of Claim 1 characterized by the above-mentioned.

  The fluororesin that forms part of the top coating component is added to obtain non-stickiness. However, as described above, the contact angle of water is too high for the fluororesin alone, and during cooking and heat insulation. Since it adversely affects the food, it is possible to obtain an appropriate water contact angle by mixing with polyethersulfone from the viewpoint of heat resistance and steam resistance.

  According to a third aspect of the present invention, there is provided a heating plate characterized by including 0.3 wt% or more and 5 wt% or less of diamond particles in a topcoat of a coating to be processed on the surface facing the pan. It is a rice cooker of Claim 1 and 2.

The diamond particles added to the top coat have the effect of improving the wear resistance, but this is derived from the property that diamond is the hardest substance in the mineral, and the amount added is 0.3% by weight. In the following, the effect of improving the wear resistance cannot be expected, and if it is 5% by weight or more, the non-adhesiveness may be adversely affected.

  A fourth aspect of the present invention is the rice cooker having a heating plate according to any one of claims 1 to 3, wherein the surface facing the lid is coated only on the periphery of the steam port.

  By treating the coating around the steam port, it is possible to prevent crevice corrosion between the packing and the heating plate, to make it a highly durable heating plate, and to keep the heat conduction from the uncoated part low, Unnecessary heating of the lid can be prevented.

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

(Embodiment 1)
Hereinafter, although the rice cooker of this invention is demonstrated, FIG. 1 shows the longitudinal cross-sectional view of the electromagnetic induction heating type rice cooker in the 1st Embodiment of this invention.

  FIG. 1 shows a rice cooker that cooks rice by heating a pan 9 by electromagnetic induction heating. A main body 1 for inserting a removable pan 9, an openable / closable lid 2, and a heating plate 7 that is detachably attached to the lid. In addition, with the electromagnetic induction heating coil 3, the ferrite 4, the pan bottom temperature sensor 8, the heating control board 5, the substrate cooling fan 10, the operation unit 6, and the steam cap 11 as main components, rice and water are added in appropriate amounts in the pan. After that, rice cooking and heat retention processes are executed, and these processes are executed by program control by a microcomputer.

  Moreover, this rice cooker is equipped with the electromagnetic induction heating coil as the heating plate heating means 12 in the lid body, and has taken the structure which heats a heating plate timely with the magnetic force line emitted from this electromagnetic induction heating coil.

  Here, the heating plate 7 used for the rice cooker of this invention is comprised using the ferrite type stainless steel 13 as a heating-plate base material so that electromagnetic induction heating may be easy as the fragmentary sectional view is shown in FIG. However, the two-layer coating 14 is processed on the surface 15 facing the pan, and the surface 16 facing the lid is mirror-finished with stainless steel.

  This coating 14 is a primer layer mainly composed of polyamide imide added with carbon black and titanium oxide as a pigment so as to be 20 μm at the time of film formation, and after drying, polytetrafluoroethylene (PTFE) particles having an average particle diameter of 5 μm and carbon A top coat paint mainly composed of polyethersulfone added with black, titanium oxide, and a bright material is applied to a thickness of 10 μm during film formation, and baked at 380 ° C. for 20 minutes to form a film.

  Here, the mixing ratio of PTFE and polyethersulfone in the top coat paint was 1: 6, but the contact angle of water was 95 ° due to this mixing ratio.

  If the resin used for topcoat coating is 100% fluororesin, such as PTFE, or if the main resin is fluororesin, the water contact angle exceeds 100 °, resulting in high water repellency and cooking. Large water droplets are formed on the coating surface, and the above-mentioned problems occur.

However, in this embodiment, since the contact angle of water is 95 °, if the temperature of the heating plate is appropriately controlled, the water droplets adhering to the coating on the surface of the heating plate do not become huge, and the water droplets fall on the cooked food. In addition, there is no fear of yellowing the food by adding extra heating power to evaporate the water droplets.

  The contact angle of water can be changed by selecting the addition ratio and particle diameter of PTFE, and polytetrafluoroethylene = perfluoroalkyl vinyl ether (PFA) or polytetrafluoroethylene = hexafluoroethylene instead of PTFE. (FEP) may be added.

  In the present embodiment, the surface 16 of the heating plate facing the lid is exposed to a high temperature of 380 ° C. during coating baking, and the stainless steel surface has an oxidation color. Therefore, pickling with hydrochloric acid or phosphoric acid after baking is performed. Alternatively, the oxide film is removed by electropolishing to obtain a mirror finish, but pickling and electropolishing are not required when firing is performed in a non-oxidizing furnace.

  The far-infrared emissivity at a wavelength of 3 to 15 μm from the surface of the fluororesin coated on the surface 15 facing the pan of the heating plate produced in this embodiment is 88%, while the stainless steel mirror surface facing the lid The far-infrared emissivity of the finished surface was 2%.

  Therefore, the heating plate provided in the rice cooker in the present embodiment having the above-described configuration has an overwhelmingly high far-infrared emissivity from the surface facing the pan, and heat is efficiently cooked from the heating plate. Although it is transmitted to the rice and water inside, far-infrared radiation from the heating plate to the lid is low, and an unnecessary temperature rise of the lid can be prevented.

(Embodiment 2)
The second embodiment of the present invention will be described below.

  The rice cooker shown in the present embodiment is of a type in which the pot 9 is heated and cooked by electromagnetic induction heating, and has the same configuration as that of the first embodiment shown in FIG. The surface to be treated is treated with two layers of coating, and the opposite surface is a mirror finish of stainless steel.

  The heating plate is coated with a primer based on polyamideimide to a thickness of 20μm, dried, and then added with polytetrafluoroethylene (PTFE) particles with an average particle size of 5μm, carbon black, titanium oxide, and a bright material. The top coating material mainly composed of polyethersulfone was applied to a thickness of 10 μm at the time of film formation, and baked at 380 ° C. for 20 minutes to form a film. Diamond fine particles having an average particle diameter of 3 μm were formed on this top coating material. Is added.

  When diamond particles are added to the top coat, the results of comparing the wear resistance performance according to the addition ratio in a wear test using a nylon scrubber are shown in (Table 1).

  The data in (Table 1) is a result of a reciprocating wear test on a coated surface applied to a commercially available nylon scrubber and comparing the number of reciprocating wear required until the substrate is exposed.

  Here, Δ is a wear resistance improvement effect of less than 1.5 times, ○ is an effect of 1.5 times or more and less than 2 times, and ◎ is 2 times or more with respect to a standard in which diamond particles are not added to the top coat. It shows that there is an effect.

  The addition of 0.3% by weight or more of diamond particles showed an effect of improving the wear resistance by 1.5 times or more compared with the addition of no diamond particles, and a clear durability improvement effect was confirmed.

  Therefore, the heating plate in the present embodiment has high wear resistance, is resistant to scratches due to care, and has high durability, so that the effect of far-infrared radiation can be maintained at the initial level for a long period.

  The average particle size of the diamond particles is preferably in the range of 1 to 5 μm because the wear resistance improving effect is not observed when the particle size is less than 1 μm, and the surface state is adversely affected when the particle size is 5 μm or more.

(Embodiment 3)
Hereinafter, the electromagnetic induction heating rice cooker which is the 3rd embodiment in the present invention is explained.

  The heating plate in the third embodiment is detachably provided in a rice cooker having the same configuration as in the first embodiment, but as in the first embodiment, ferrite is used so that electromagnetic induction heating is easy. The surface facing the pan is treated with two layers of coating, and the surface facing the lid is mirror-finished with stainless steel.

  However, as shown in FIG. 3, the same coating 21 as that processed on the surface facing the pan is treated around the steam port 20 on the surface facing the lid.

  This is because the steam port is a passageway for steam and rice balls, and is easily corroded, and since the area around the steam port is a contact part with the packing, crevice corrosion is likely to occur. Can be improved.

(Embodiment 4)
FIG. 4 is a partial cross-sectional view of a heating plate used in an electromagnetic induction heating rice cooker showing a fourth embodiment of the present invention.

  The rice cooker in the present embodiment is a method of heating and cooking the pot 9 by electromagnetic induction heating, and has the same configuration as that of the first embodiment shown in FIG. 1, but this rice cooker is heated in the lid. An electromagnetic induction heating coil is provided as the heating means 12 of the plate 7, and an acrylic paint added with 20% by weight of a glass balloon having an average particle diameter of 10 μm is applied to the surface 23 of the lid opposite to the heating plate. There is a heat reflecting layer 22 having a thickness of 30 μm.

  Because far infrared rays are reflected by adding glass balloons, the lid temperature is unlikely to rise even when receiving heat from the heating plate, and the lid body is thermally deformed and the temperature of electronic parts and structural parts inside the lid The rise can be suppressed, and as a result, a highly durable rice cooker can be obtained.

  The heating plate of the rice cooker according to the present invention can be applied not only to consumer use but also to a commercial rice cooker.

The longitudinal cross-sectional view of the rice cooker in Embodiment 1 of this invention. Partial sectional view of a heating plate in Embodiment 1 of the present invention The top view of the surface facing the cover body of the heating plate with which the rice cooker in Embodiment 3 of this invention is mounted | worn. Cross-sectional view of the vicinity of the lid of the rice cooker in Embodiment 4 of the present invention

DESCRIPTION OF SYMBOLS 1 Main body 2 Lid body 7 Heating plate 9 Pan 13 Hot plate base material 14 Coating 15 Surface facing a pan 16 Surface facing a lid 20 Steam port 22 Heat reflection layer

Claims (4)

In a rice cooker having a main body, a pan detachably accommodated in the main body, an openable / closable lid, and a metal heating plate detachably attached to the lid, the surface facing the heating plate of the lid The surface of the heating plate facing the pan is coated, and the surface of the coating is controlled to have a water contact angle of 80 to 100 °, and the heating plate lid The rice cooker characterized in that the surface facing the surface has a surface finish with a far-infrared emissivity of 10% or less at a wavelength of 3 to 15 μm. The top coat of the coating to be processed on the surface opposite to the pan of both surfaces of the heating plate is formed by painting a paint mainly composed of polyethersulfone with the addition of fluorinated resin. The rice cooker according to claim 1. The top coat of the coating to be processed on the surface opposite to the pan among both surfaces of the heating plate has a heating plate characterized by containing 0.3% by weight or more and 5% by weight or less of diamond particles. The rice cooker according to claim 1 or 2. The rice cooker having a heating plate according to any one of claims 1 to 3, wherein the surface facing the lid is coated only on the periphery of the steam port.