JP4347306B2 - Cooking container for induction heating cooker and method for manufacturing cooking container for induction heating cooker - Google Patents

Description

  The present invention relates to a high-temperature cooker such as a rice cooker pot heated by electromagnetic induction or the like, and more specifically, an outer surface of a molded product made of porous ceramics such as a material obtained by sintering carbon particles. In particular, the present invention relates to a technique for forming a coating film having excellent air permeability, mainly composed of a resin having high heat resistance such as silicone resin.

Among cookware that cooks at high temperatures such as rice cookers and pots, porous molded products made by agglomerating carbon and ceramic powder particles prevent excessive impregnation and sticking of liquid ingredients from the surface. Therefore, it is modified by painting its surface. Furthermore, since the surface of the porous molded product formed by condensing powder particles is brittle, the outer surface is also coated to improve the wear resistance.
Japanese Patent Laid-Open No. 10-211091

  However, if moisture penetrates into the interior of a porous molded product that has been modified by painting on the surface, moisture will evaporate and vaporize due to heating during cooking. The coating film may be peeled off due to an excessive increase in pressure.

  The present invention has been made to solve the above-described problems. When cooking is heated, the gas that remains in the porous molded product in which the powder particles condense is discharged to the outside. The present invention provides a cooking container for an induction heating cooker and a method for manufacturing a cooking container for an induction heating cooker that suppresses outward stress applied to the coating film and is less likely to cause blistering of the coating film during use. For the purpose.

  A cooking container of an induction heating cooker according to the present invention is a cooking container of an induction heating cooker using a porous ceramic aggregate, and a flat filler or a particulate filler is provided on the outer surface of the cooking container. A permeable protective layer formed by removing the volatile solvent after spraying the contained resin liquid and drying is provided.

  The cooking container of the induction heating type cooker according to the present invention has a resin in the vicinity of the inter-particles of the flat filler or the particulate filler in which the shrinkage stress accompanying the drying and curing of the resin is arranged in the plane direction by the above configuration. It is possible to form cavities that are fine and continuous cracks. As a result, when cooking is heated, it is possible to release the gas that expands by remaining in the porous ceramics agglomerated powder particles, so that the outward stress on the coating is suppressed and being used. The effect of not causing blistering is obtained.

Embodiment 1 FIG.
FIG. 1 to FIG. 5 are diagrams showing Embodiment 1, FIG. 1 is a manufacturing process diagram of a pot-shaped workpiece, FIG. 2 is an inner coating process diagram of the pot-shaped workpiece, and FIG. 3 is an outer surface coating of the pot-shaped workpiece. 4 is a conceptual diagram of a silicone resin impregnated state ((a) is a conceptual diagram of a silicone resin impregnated state in the vicinity of a painted surface, (b) is a conceptual diagram of a reinforcing state between carbon particles), and FIG. 5 is a painted surface The conceptual diagram which shows the formation state of the cavity by a cross section ((a) is a conceptual diagram which shows the state which the mica powder contained excessively in the coating film formed in the outermost layer, (b) is the fine which generate | occur | produces in a silicone resin It is a conceptual diagram which shows a crack.

  Using a carbon condensate that generates heat by receiving induction current due to the magnetic field generated by the current flowing in the heating coil of the induction heating cooker, and achieves uniform heating based on excellent thermal conductivity to improve rice cooking performance The manufacturing method of the inner pot (an example of a cooking container) of a rice cooker (an example of an induction heating type cooking device) will be described in detail below.

First, the manufacturing process of a carbon aggregate (an example of a porous ceramic aggregate) will be described with reference to FIG. A precursor obtained by heating to 300 ° C. and adding a petroleum tar pitch in a molten state to a raw material mainly composed of coke powder and then kneading and molding into a block shape (S10) is obtained at 1000 ° C. Sintered in an oxygen-free state (S20), and further heat-treated in an oxygen-free state at 3000 ° C. (S30), so that the carbon is condensed with a purity of 99.9% or more and a density of about 1.7 g / cm ³ The body is obtained. This carbon aggregate is cut using a lathe and processed into a hook shape with a wall thickness of 5 mm (S40). At this time, it is important to remove the cutting waste by sucking it during cutting so that the cutting waste does not remain in the pores and impede impregnation with a liquid resin described later.

Next, the inner surface coating of the pot-shaped workpiece will be described with reference to FIG.
First, 10 volume% of FEP (tetrafluoroethylene / hexafluoropropylene copolymer (4.6 fluoride)) fine powder is dispersed in an aqueous dispersion of PES (polyether sulfone) to reduce the pressure to 200 cP (centipoise). Using a liquid resin that is a viscosity as a primer, and using a spray to divide it into multiple times using a spray so that the inner surface corresponding to the cooking surface of the pot-shaped processed product is sufficiently impregnated into the pot-shaped processed product, It sprays until it remains thinly on the surface (S50).

  Thereafter, the liquid resin sprayed on the inner surface of the pot-shaped workpiece is secured in a dry state by heat treatment at 200 ° C. for 20 minutes (S60). A fine powder of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) that is compatible with FEP is uniformly attached to the dried surface of the liquid resin (S70). Then, it melt | dissolves by heating for 30 minutes in a 370-400 degreeC furnace, and forms the inner surface coating film of the smooth PFA thin film of the pot-shaped processed material of a carbon aggregate (S80).

  The coating of the fluororesin formed on the inner surface of the pot-shaped workpiece by the process of FIG. 2 forms a coating film that does not contain pores such as pinholes, so even if liquid ingredients are added and used for cooking Since it does not leak and has a feature that there is little risk of sticking even if burnt due to excessive heating occurs, it is convenient for use as a cooking container.

  Next, with respect to the inner surface coating of the hook-shaped workpiece described above, the outer surface coating, which is a characteristic part of the present embodiment, is performed on the outer surface corresponding to the facing surface of the pot-shaped workpiece wall. With reference to FIG. 3, the outer surface coating process of the pot-shaped workpiece will be described.

  The paint used to coat the outer surface of the pot-shaped workpiece is a silicone resin (an example of a resin liquid) using thinner as a volatile solvent, and mica (an example of a flat filler) having a diameter of 0.05 to 0.3 mm. 30% by volume and uniformly dispersed, and sprayed onto the outer surface of the pot-shaped workpiece by spraying (S90), and then cured to form a coating film on the outer surface (S100).

  The pot-shaped workpiece formed by the condensation of carbon is porous and has many voids between the particles. In other words, since there are few parts to which the carbon particles are bonded, the lack of particles easily occurs, and as a result, the coating surface is easily peeled off simply by applying the coating surface, and the carbon itself is also separated from the resin. There is a disadvantage that it is inferior in adhesion.

  For this reason, as shown in FIG. 3, by spraying a paint such as a silicone resin, the carbon aggregate 1 of the carbon particles as a base material in the vicinity of the surface is impregnated with the silicone resin 2 of the paint, and the carbon particles 1a In addition to reinforcing the bond between them, the silicone resin 2 is made to enter the gap 1b formed by contact of the condensed carbon particles 1a (FIG. 4 (a)) to reinforce so as to cover the contact portion between the carbon particles 1a. (FIG. 4B) improves the apparent adhesiveness.

  At the same time, as shown in FIG. 5, the mica powder-containing silicone resin 3 (an example of a protective layer) that is a coating film formed on the outermost layer is in a state in which mica powder is excessively contained ( FIG. 5 (a)). The mica 3a in the mica powder-containing silicone resin 3 is arranged in parallel with the surface of the molded product, and the resin liquid remains in the voids formed between the mica 3a particles. Since the molded product coated in this state is put into a furnace at 280 ° C. and dried, the thinner, which is the solvent contained in the resin liquid, is diffused and shrinks to generate voids.

  The formation of voids due to solvent evacuation during drying after coating is due to the fact that the shrinkage stress generated during solvent evacuation easily shrinks in the thickness direction and releases the stress, whereas Since the deformation is restrained by the molded product or the oriented mica 3a and hardly contracts, the tensile stress acts on the silicone resin 2 having a sufficiently lower strength than the mica 3a, and the mica 3a and the silicone resin 2 A fine crack 4 is generated in the immature cured silicone resin 2 in the vicinity of the contact interface with the resin to form a continuous fine cavity to release the stress (FIG. 5B).

  The internal pressure of the pot-shaped processed product used for cooking rice rises due to the expansion of air in the voids 1b existing inside the carbon aggregate 1 generated during heating, or the vaporization of moisture or the like that has entered from defective portions due to surface damage. Sometimes. If the coating on the outer surface is sealed and sealed, outward stress will be generated in the coating on the inner and outer surfaces, so that peeling will occur at sites that are inferior in close contact with the carbon aggregate 1 become.

  The adhesiveness between the mica 3a and the silicone resin 2 is sufficiently expressed in the curing process of the silicone resin 2, but as the curing progresses, the adhesiveness rapidly decreases so that peeling easily occurs. Therefore, a continuous cavity accompanying the peeling is generated at the interface portion with the mica 3a.

  2 and 3 show that the inner and outer surfaces of the hook-shaped workpiece are coated with an inner surface that does not have any pinholes and blocks air flow, whereas the outer surface coating has a cavity and air permeability. Therefore, the gas in the gap 1b included in the carbon aggregate 1 forming the pot-shaped molded product causes a rapid temperature rise due to heating during cooking, and the gas inside the pot-shaped workpiece expands to the painted surface. Even if this pressure is increased, it is possible to suppress the generation of stress that easily releases the expanded gas to the outside and peels off the painted surface, and improves the apparent adhesive force between the painted surface and the carbon aggregate 1. Therefore, peeling can be prevented.

  Here, the silicone resin 2 is used as the paint, but it is not necessary to stick to the above-mentioned resin as long as it has a heat resistance higher than the maximum temperature that the cooking utensil receives. For example, heat such as epoxy resin or polyester resin can be used. In addition to the curable resin, a heat-resistant thermoplastic resin such as polyphenylene sulfide (PPS), polysulfone (PSU), or polyether ether ketone (PEEK) may be used.

  In addition, when using the above-mentioned resin which is excellent in adhesiveness compared to the silicone resin 2 used in the present embodiment, the surface of the filler such as mica 3a is coated with an agent that promotes non-adhesiveness. It is preferable to use one having an aspect that inhibits adhesion with the resin forming the protective layer.

  Further, although the mica 3a is used as the flat filler, it may be replaced with boron nitride, alumina or the like which is a particulate filler. Similarly, various modes may be used, for example, by changing to a brushing or dipping method as a coating method.

  In the above-described embodiment, description has been given of the case where the pot-shaped workpiece is constituted by the carbon aggregate, but other than the carbon aggregate, for example, pottery or the like may be used. These are collectively called a porous ceramic aggregate.

It is a figure which shows Embodiment 1 and is a manufacturing-process figure of a pot-shaped processed material. It is a figure which shows Embodiment 1, and is an inner surface coating process figure of a pot-shaped workpiece. It is a figure which shows Embodiment 1, and is an outer surface coating process figure of a pot-shaped workpiece. FIG. 2 is a diagram illustrating the first embodiment, and is a conceptual diagram of a silicone resin impregnated state ((a) is a conceptual diagram of a silicone resin impregnated state in the vicinity of a painted surface, and (b) is a conceptual diagram of a reinforcing state between carbon particles). The figure which shows Embodiment 1 and is a conceptual diagram which shows the formation state of the cavity by the coating surface cross section ((a) is a conceptual diagram which shows the state which the mica powder contained excessively in the coating film formed in the outermost layer) (B) is a conceptual diagram which shows the fine crack which generate | occur | produces in a silicone resin.

Explanation of symbols

  1 carbon aggregate, 1a carbon particle, 1b void, 2 silicone resin, 3 mica powder-containing silicone resin, 3a mica, 4 crack.

Claims (3)

In a cooking vessel of an induction heating type cooker using a porous ceramic aggregate,
Air permeability with continuous fine cavities that are cracks generated by removing volatile solvent after spraying a resin liquid containing a flat filler or particulate filler on the outer surface of the cooking vessel A cooking container for an induction heating cooker, comprising a protective layer. In the method of manufacturing a cooking container of an induction heating type cooker using a porous ceramic aggregate,
The outer surface of the cooking vessel, the volatile solvent after spraying the plate-like filler or a resin solution containing a particulate filler was removed and the continuous fine voids are cracks that occur when Ru dried The manufacturing method of the cooking container of the induction heating type cooking appliance characterized by forming the air-permeable protective layer provided . The adhesiveness between the flat filler or particulate filler and the resin forming the protective layer is such that the adhesiveness decreases with the progress of curing of the resin to form continuous fine cavities. The method for manufacturing a cooking container of an induction heating type cooking device according to claim 2,

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