JP2007195632A - Inner pot for rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inner pot for a rice cooker, which is formed with a projecting scale as a cooking reference while preventing its peeling when the inner pot of the rice cooker is composed of a ceramic material. <P>SOLUTION: This inner pot 2 for the rice cooker is stored in an inner pot retaining part in a rice cooker body 1, and is formed by covering the surface of a pot-shaped base material 3 with a glaze layer 4; and both of the base material 3 and the glaze layer 4 are formed of the ceramic material. The surface of the glaze layer 4 in the internal circumferential face 21 of the inner pot is provided with the projecting scale 5 as the cooking reference. The projecting scale 5 is formed into a projecting height of 5-100 μm by baking glass paste formed by mixing glass flux, organic binder and inorganic pigment on the surface of the glaze layer 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rice cooker inner pot accommodated in an inner pot holding portion of a rice cooker body.

2. Description of the Related Art Currently used household or commercial electric rice cookers or gas rice cookers are generally provided with an inner pot for heating rice and water. The inner pot is mostly made of metal such as iron or aluminum alloy, and its surface is often treated with fluororesin for the purpose of preventing scorching and facilitating removal of dirt.
However, the fluorine film formed by fluororesin processing is damaged by repeated cooking and repeated washing. In addition, the fluorine coating may be peeled off over a long period of time, and in this case, the peeled fluorine coating may be mixed with the cooked rice or may be easily burnt.

  On the other hand, inner pots made of ceramics have begun to be used recently because of the high-class genuine intention to eat delicious food. Since this inner pot is made of ceramics, it has better heat retention than conventional metal pots, and it is thought that cooked rice can be cooked deliciously by the effect of far infrared rays emitted from the heated ceramics. It is done.

As an example of a rice cooker using a ceramic inner pot, there is an induction heating type rice cooker disclosed in Patent Document 1, for example. In this induction heating rice cooker, the inner pot is made of ceramics, and the portion of the inner pot facing the heating means is formed from a multilayer structure of ceramics and metal, and a temperature sensor is brought into contact with the metal.
Patent Document 2 discloses a ladle pot composed of a metal outer pot such as iron to be heated and a porous unglazed inner pot that can be inserted into and removed from the outer pot. In this oat pot, by using an unglazed inner pot, even if the inner cover such as fluororesin is peeled off from the outer pot, the peeled inner cover is not mixed with the rice. In addition, it is also considered that in this Otsuka, the existing Otsuka is diverted, and an unglazed inner pot is arranged on the existing Otsuka.

  Patent Document 3 discloses a clay pot for cooking rice having a pot body formed by sintering ceramic clay. The inner wall surface of the pan body of this rice cooking pot is provided with a metal spraying heat generation layer and a metal spraying heat transfer layer, and the surface of the metal spraying heat transfer layer is covered with rice and water charged at a predetermined rate during rice cooking. A plurality of charging volume index portions each indicating the height position for each appropriate charging amount of the heated object are provided.

However, when applying an inner pot made of ceramics in a rice cooker, a technique for providing a scale serving as a standard for cooking rice without causing peeling on the inner peripheral surface of the inner pot is disclosed in Patent Publications 1-3. Not.
For example, in Patent Document 3, a pot body (inner pot) is configured using porcelain that is a raw material for ceramics, and a charged volume index portion (scale) is a metal spray heat transfer made of a metal film such as aluminum or silver. Formed on the surface of the layer. Therefore, there is a possibility that the metal sprayed heat transfer layer including the charging volume index portion may be peeled off from the pan body due to a large difference in thermal expansion between the clay and the metal film.

  In particular, when the rice cooker is a gas rice cooker that uses gas fuel to cook rice, the inner pot is directly heated by the combustion flame. Therefore, in this case, in order to cook cooked rice such as rice deliciously, it is necessary to consider the influence that the cooked rice has when the inner pot comes into contact with the combustion flame. It is not disclosed in 1-3.

JP 2005-304709 A JP-A-9-56580 Utility Model Registration No. 3110038

  The present invention has been made in view of such conventional problems, and when the inner pot for a rice cooker is made of a ceramic material, it can prevent peeling and form a convex scale serving as a standard for cooking rice. It is intended to provide an inner pot.

The present invention is a rice cooker inner pot accommodated in the inner pot holding portion of the rice cooker body,
The inner pot is formed by coating the surface of a container-shaped base material with a glaze layer, and the base material and the glaze layer are both made of a ceramic material,
The surface of the glaze layer on the inner peripheral surface of the inner pot is provided with a convex scale serving as a standard for cooking rice,
The convex scale is formed with a protruding height of 5 to 100 μm by baking a glass paste,
The glass paste is a mixture of glass flux, organic binder, and inorganic pigment,
The glass flux, the thermal expansion coefficient of ^{4.5 × 10 -6 /℃~7.0×10 -6 / ℃} , the SiO ₂ 42-67 wt%, 5 to 10 weight Al ₂ O ₃ %, B ₂ O ₃ and 18 to 23 wt%, MgO, CaO, 1 or 2 or more in total 2-5% by weight selected from the group of SrO and _{BaO, Li 2 O, Na 2} O and K ₂ A rice cooker inner pot comprising 5 to 10% by weight of a total of one or more selected from the group of O and 3 to 10% by weight of ZrO ₂ (Claim 1). .

The inner pot for a rice cooker of the present invention is formed by coating the surface of a base material made of a ceramic material with a glaze layer made of a ceramic material.
And the inner pot of this invention is excellent in heat resistance by comprising both the base material and the glaze layer from the ceramic material. In addition, because of the excellent heat resistance, particularly when the inner pot is used in a gas rice cooker, it is possible to cook rice by directly bringing a combustion flame into contact with the inner pot. Thereby, cooked rice, such as rice, can be cooked deliciously.

Further, the inner pot of the present invention is excellent in durability because the base material and the glaze layer are both made of a ceramic material, and the glaze layer is hardly peeled off from the base material. Moreover, the inner pot of the present invention is superior in heat retention compared to a metallic inner pot.
Furthermore, convex scale as the cooking guide, the thermal expansion coefficients are formed by baking a glass paste using a glass flux is 4.5 × 10 ^-6 /℃~7.0×10 ^-6 / ℃ . Therefore, the difference in thermal expansion between the glass flux and the ceramic material is small, and it is possible to effectively prevent the convex scale from peeling off from the glaze layer in the inner pot.

Moreover, the convex scale is not only visually recognized by protruding from the surface of the glaze layer with a protruding height of 5 to 100 μm, but also tactilely (by touching with the hand). You can also.
Moreover, it can prevent more effectively that a convex scale will peel from the glaze layer in an inner pot by comprising the glass flux which comprises a convex scale with the said composition.

  Therefore, according to the present invention, when the inner pot for a rice cooker is made of a ceramic material, it is possible to prevent the peeling and form a convex scale serving as a standard for cooking rice.

A preferred embodiment of the present invention described above will be described.
In the present invention, when the coefficient of thermal expansion of the glass flux constituting the convex scale is less than 4.5 × 10 ⁻⁶ / ° C., the melt adhesion of the glass flux becomes insufficient, and the convex scale is There is a possibility that the glaze layer on the surface of the substrate is not sufficiently adhered.
On the other hand, when the thermal expansion coefficient of the glass flux constituting the convex scale exceeds 7.0 × 10 ⁻⁶ / ° C., the convex scale is peeled off after baking the convex scale on the surface of the glaze layer. May occur.

Moreover, when the protrusion height of the said convex scale is less than 5 micrometers, there exists a possibility that the rice cooking standard by this convex scale cannot be recognized tactilely (by touching with a hand).
On the other hand, when the protruding height of the convex scale exceeds 100 μm, the convex scale may be lost and peeled off after the convex scale is baked on the surface of the glaze layer.

Further, in the composition of the glass flux constituting the convex scale, when the SiO ₂ content is less than 42% by weight, the thermal expansion coefficient of the glass flux is increased, and the convex scale may be peeled off. is there.
On the other hand, when the content of SiO ₂ exceeds 67% by weight, the viscous flow of the glass flux is increased, the smoothness of the surface of the convex scale is lost, and the antifouling property of the convex scale may be deteriorated. is there.

Moreover, in the composition of the glass flux constituting the convex scale, when the content of Al ₂ O ₃ is less than 5% by weight, the alkali resistance may be deteriorated.
On the other hand, when the content of Al ₂ O ₃ exceeds 10% by weight, the viscous flow of the glass flux becomes high, the smoothness of the surface of the convex scale is lost, and the antifouling property of the convex scale is deteriorated. There is a fear.

Further, in the composition of the glass flux constituting the convex scale, when the content of B ₂ O ₃ is less than 18% by weight, the thermal expansion coefficient of the glass flux is increased, and the acid resistance may be deteriorated. is there.
On the other hand, when the content of B ₂ O ₃ exceeds 23% by weight, the alkali resistance may be deteriorated.

In the composition of the glass flux constituting the convex scale, when the total content of one or more selected from the group of MgO, CaO, SrO and BaO is less than 2% by weight, the glass flux There is a risk that the viscous flow of the convex scale becomes high, the smoothness of the surface of the convex scale is lost, and the antifouling property of the convex scale is deteriorated.
On the other hand, when the total content of one or more selected from the group of MgO, CaO, SrO and BaO exceeds 5% by weight, the thermal expansion coefficient of the glass flux may be remarkably increased. Moreover, there exists a possibility that alkali resistance may deteriorate.

Further, in the composition of the glass flux constituting the convex scale, when the total content of one or more selected from the group of Li ₂ O, Na ₂ O and K ₂ O is less than 5% by weight The viscosity flow of the glass flux increases, the smoothness of the surface of the convex scale is lost, and the antifouling property of the convex scale may be deteriorated.
On the other hand, when the total content of one or more selected from the group of Li ₂ O, Na ₂ O, and K ₂ O exceeds 10% by weight, the thermal expansion coefficient of the glass flux is remarkably increased, and the convexity Cracks and peeling easily occur on the scale. Moreover, there exists a possibility that alkali resistance may deteriorate.

Further, in the composition of the glass flux constituting the convex scale, when the ZrO ₂ content is less than 3% by weight, the acid resistance may be deteriorated.
On the other hand, when the content of ZrO ₂ exceeds 10% by weight, the viscous flow of the glass flux becomes high, the smoothness of the surface of the convex scale is lost, and the antifouling property of the convex scale may be deteriorated. is there.

Moreover, as said organic binder, the 1 type (s) or 2 or more types chosen from an acrylic resin, an alkyd resin, an ethosell resin, and a butyl resin can be used.
Examples of the inorganic pigment include black (Cr—Fe, Co—Mn—Cr—Fe, Co—Ni—Cr—Fe, Co—Ni—Cr—Fe—Mn, etc.), gray (Sn—Sb, Sn-Sb-V, etc.), yellow (Sn-V, Zr-V, Zr-Si-Pr, Ti-Cr-Sb, Zr-Si-Cd-S, CdS, etc.), brown (Zn-Al-Cr- Fe, Zn-Mn-Al-Cr-Fe, etc.), green (Ca-Cr-Si, Cr-Al, Co-Zn-Al-Cr, Zr-Si-Pr-V, etc.), blue (Co-Al- Zn, Co-Al, Co-Si, Zr-Si-V, etc.), pink (Mn-Al, Ca-Sn-Si-Cr, Sn-Cr, Zr-Si-Fe, etc.), red (Zr-Si-) Cd-Se-S, Cd-Se-S, etc.), which can be mixed in any proportion to obtain the desired color. Can.

Further, the substrate is water absorption with a coefficient of thermal expansion of 1.0 × 10 ^-6 /℃~3.0×10 ^-6 / ℃ is 2.0 to 8.0%, the glaze layer preferably, the thermal expansion coefficient greater than the base material, and is the thermal expansion coefficient of ^{2.0 × 10 -6 /℃~5.0×10 -6 / ℃} ( claim 2).

The thermal expansion coefficient of the substrate is that ^{1.0 × 10 -6 /℃~3.0×10 -6 / ℃} , thermal expansion coefficient of the glaze layer is 2.0 × 10 ^-6 / ℃ ~5. When it is 0 × 10 ⁻⁶ / ° C., when a glaze layer is formed by applying a ceramic material to the surface of the base material and firing it, the glaze layer is less likely to be cracked or damaged. it can. Moreover, when cooking rice with the said inner pot, it can make it hard to generate | occur | produce a damage to a glaze layer.

Moreover, while the water absorption rate of the said base material is 2.0 to 8.0%, while a base material can absorb a water | moisture content moderately before performing rice cooking, when performing rice cooking, it is water | moisture content appropriately. Can be released. Thereby, cooked rice, such as rice, can be cooked deliciously.
The water absorption rate is a scale indicating the ease of moisture absorption of the substrate. The saturated mass when moisture is absorbed to a saturated state by the substrate is A, and the substrate absorbs moisture. When the dry mass when not present is B, it means a value represented by (A−B) / B × 100%.

In addition, when the thermal expansion coefficient of the base material is less than 1.0 × 10 ⁻⁶ / ° C., after firing the glaze layer on the surface of the base material, due to the difference in thermal expansion between the base material and the glaze layer, There is a risk that the glaze layer may crack and the glaze layer may peel off. On the other hand, when the thermal expansion coefficient of the base material exceeds 3.0 × 10 ⁻⁶ / ° C., the base material may be cracked or damaged when it is rapidly cooled when used as an inner pot. .

Moreover, when the thermal expansion coefficient of the glaze layer is less than 2.0 × 10 ⁻⁶ / ° C., the gloss, smoothness and the like of the glaze layer may be deteriorated. On the other hand, when the thermal expansion coefficient of the glaze layer exceeds 5.0 × 10 ⁻⁶ / ° C., after the glaze layer is baked on the surface of the base material, the glaze is caused by the difference in thermal expansion between the base material and the glaze layer. There is a risk that the layer will crack and the glaze layer may peel off.

  Also, when the substrate has a water absorption rate of less than 2.0%, when used as an inner pot, when the substrate is rapidly heated while containing moisture, the substrate is vaporized. There is a risk of cracks and breakage due to expansion. On the other hand, when the water absorption rate of the base material exceeds 8.0%, the strength of the base material is deteriorated, and there is a possibility that the base material may be cracked or damaged due to impact or the like.

The ceramic material constituting the base material contains one or more of β-spodumene, β-eucryptite and cordierite, mullite and quartz, and constitutes the glaze layer. Preferably, the ceramic material contains one or more of β-spodumene, β-eucryptite, and cordierite, and mullite, quartz, boron-based glass, and an inorganic pigment. 3).
In this case, the composition of each ceramic material is appropriate, and the occurrence of damage such as cracks or breakage in the glaze layer can be effectively prevented.

Below, it explains about an example concerning an inner pot for rice cookers of the present invention with a drawing.
The rice cooker inner pot 2 of this example is accommodated in the inner pot holding part 11 of the rice cooker body 1 as shown in FIGS. This inner pot is formed by coating the surface of a container-shaped base material 3 with a glaze layer 4, and both the base material 3 and the glaze layer 4 are made of a ceramic material.
Moreover, as shown in FIG. 3, the convex scale 5 used as a rice cooking standard is provided in the surface of the glaze layer 4 in the internal peripheral surface 21 of an inner pot. The convex scale 5 is formed with a protruding height of 5 to 100 μm by baking a glass paste formed by mixing a glass flux, an organic binder and an inorganic pigment on the surface of the glaze layer 4.

The glass flux is the thermal expansion coefficient of ^{4.5 × 10 -6 /℃~7.0×10 -6 / ℃} . The glass flux, a SiO ₂ 42 to 67 wt%, the Al ₂ O ₃ 5 to 10 wt%, selected a B ₂ O ₃ 18 to 23 wt%, MgO, CaO, from the group of SrO and BaO 1 2 to 5% by weight of the total of the seeds or two or more, 5 to 10% by weight of the total of one or more selected from the group of Li ₂ O, Na ₂ O and K ₂ O, and 3 of ZrO ₂ -10% by weight.

Below, it explains in full detail with FIGS. 1-3 about the inner pot 2 for rice cookers of this example.
As shown in FIG. 1, the rice cooker body 1 of this example is a gas rice cooker that cooks using gas fuel F, and a burner 12 that burns using gas fuel F is disposed at the bottom 31 thereof. It becomes. And when the said inner pot 2 is accommodated in the inner pot holding | maintenance part 11 of a gas rice cooker and cooking is performed, the combustion flame H by the burner 12 contacts the bottom 31 of the inner pot 2, and this inner pot 2 is Can be heated.

In addition, the rice cooker main body 1 can be equipped with the thermal insulation means for performing the thermal insulation of the cooked rice after cooking. As this heat retaining means, an electric heater or the like can be used.
Moreover, the rice cooker main body 1 is provided with an operation panel 13 having operation switches for controlling rice cooking and heat retention.

As shown in FIG. 2, the base material 3 is formed by a bottom portion 31 and a side wall portion 32 erected in an annular shape from the outer peripheral end portion of the bottom portion 31.
On the lower surface of the bottom portion 31 of the inner hook 2, a protruding portion 311 that protrudes downward is formed. The glaze layer 4 is coated on the entire surface of the base material 3 other than the lower surface 312 of the protrusion 311. The base material 3 made of a ceramic material can suck up moisture from the lower surface 312 of the projecting portion 311 and release moisture from the lower surface of the projecting portion 311.

  Further, as shown in the figure, a flange 33 protruding in the radial direction is formed at the upper end opening 30 (the upper end of the side wall 32) of the inner hook 2 of this example. On the inner side, a recess 331 in which an upper lid 35 made of a ceramic material is disposed is formed. And when the inner pot 2 of this example is taken out from the rice cooker main body 1, the upper cover 35 can be arrange | positioned to the said recessed part 331, and it can be used as a hook pot. At this time, since both the inner hook 2 and the upper lid 35 are made of a ceramic material, the inner hook 2 can be used as a hook pot having excellent heat retention.

The ceramic material constituting the substrate 3 (ceramic material for the substrate) includes ceramic components such as β-spodumene, β-eucryptite and cordierite for forming a low expansion substrate, mullite and quartz. And containing.
Further, the ceramic material (glazing ceramic material) constituting the glaze layer 4 is composed of ceramic components such as β-spodumene, β-eucryptite, cordierite, etc. for forming a low expansion substrate, mullite and quartz, It contains boron glass for maintaining the smoothness of the surface of the glaze layer 4 after firing, and an inorganic pigment for coloring.

Ceramic material constituting the substrate 3 to form a 1.0 × 10 ^-6 /℃~3.0×10 ^-6 / ℃ substrate 3 in the thermal expansion coefficient, for producing the ceramic component It contains about 40% petalite. And the thermal expansion coefficient of the base material 3 of this example was 1.9 × 10 ⁻⁶ / ° C., and the water absorption rate of the base material 3 was 5.0%.
Moreover, the ceramic material constituting the glaze layer 4, in order to form a glaze layer 4 of 2.0 × 10 ^-6 /℃~5.0×10 ^-6 / ℃ thermal expansion coefficient, produce the ceramic component Therefore, it contains about 20% of petalite. And the thermal expansion coefficient of the base material 3 of this example was 3.5 × 10 ⁻⁶ / ° C.

Moreover, the base material 3 formed by baking the said ceramic material for base materials at 1000-1200 degreeC. The glaze layer 4 was formed by applying the glaze ceramic material on the surface of the substrate 3 and firing at 1100 to 1300 ° C. The glaze layer 4 was formed to a thickness of 100 to 300 μm.
Moreover, as a glass flux for forming the said convex scale 5, what has a particle size of 0.8-6.0 micrometers was used. Moreover, as a glass flux of this example, the one whose yield point is 540-640 degreeC, a refractive index is 1.45-1.55, and a density is 2.2-2.5 g / cm < ³ > is used. It was.

Further, the glass paste was constituted by mixing 70 to 150 parts by weight of an organic binder with respect to 100 parts by weight of the total of the glass flux 70 to 99.9% by weight and the inorganic pigment 0.1 to 30% by weight. .
An acrylic resin was used as the organic binder.
When the mixing amount of the organic binder is less than 70 parts by weight, the surface state when the glass paste is printed is poor, and the surface state of the convex scale 5 after firing may be deteriorated. On the other hand, when the mixing amount of the organic binder exceeds 150 parts by weight, the glass paste spreads and the protruding height of the convex scale 5 may be lowered, and the decorative design by the convex scale 5 is blurred. There is a risk of it.

  More specifically, the convex scale 5 is formed by forming a transfer sheet provided with decorative patterns such as letters and figures from a glass paste, and then attaching the transfer sheet to the surface of the glaze layer 4 by a so-called transfer technique. And then baked (baked) at a temperature of 750 to 1000 ° C. Moreover, the convex scale 5 was formed with a protruding height of 5 to 100 μm with respect to the surface of the glaze layer 4.

  In addition, when the baking temperature at the time of forming the convex scale 5 is less than 750 ° C., the baking of the convex scale 5 becomes difficult, and the smoothness of the surface of the convex scale 5 is lost (the surface is The dirt removal property and chemical resistance of the convex scale 5 may be deteriorated. On the other hand, when the firing temperature at the time of forming the convex scale 5 exceeds 1000 ° C., the glass paste spreads and the protruding height of the convex scale 5 may be lowered. There is a risk that the decorative design will blur.

The inner pot 2 for the rice cooker of this example is used for a gas rice cooker that cooks using gas fuel F, and the surface of a base material 3 made of a ceramic material is covered with a glaze layer 4 made of a ceramic material. .
And the inner pot 2 of this example is excellent in heat resistance by comprising both the base material 3 and the glaze layer 4 from the ceramic material. In addition, since the heat resistance is excellent, particularly in the case of the present example in which the inner pot 2 is used in a gas rice cooker, the cooking flame H can be directly brought into contact with the inner pot 2 to perform rice cooking. Thereby, cooked rice, such as rice, can be cooked deliciously.

  Moreover, the inner pot 2 of this example is excellent in durability because the base material 3 and the glaze layer 4 are both made of a ceramic material, so that the glaze layer 4 is difficult to peel off from the base material 3. Moreover, the inner hook 2 of this example is excellent in heat retention compared with the metallic inner pot 2. Further, since the surface of the base material 3 is covered with the glaze layer 4, dirt is prevented from adhering to the inner pot 2, and water put in the inner pot 2 is allowed to flow from the inner peripheral surface 21 of the inner pot 2. It is possible to prevent penetration into the inside of the substrate 3.

The thermal expansion coefficient of the substrate 3 are ^{1.0 × 10 -6 /℃~3.0×10 -6 / ℃} , the thermal expansion coefficient of the glaze layer 4 is 2.0 × 10 ^-6 / ℃ ~ Due to being 5.0 × 10 ⁻⁶ / ° C., when a glaze layer 4 is formed by applying a ceramic material to the surface of the base material 3 and firing, damage such as cracks or breakage occurs in the glaze layer 4 Can be difficult. In addition, when the rice is cooked by the inner pot 2, the glaze layer 4 can be hardly damaged.

  Moreover, while the water absorption rate of the base material 3 is 2.0-8.0%, it can absorb water | moisture content moderately before cooking rice, and discharge | releases water | moisture content appropriately when cooking rice. Can do. Thereby, cooked rice, such as rice, can be cooked deliciously. The water absorption rate of the base material 3 varies depending on the ratio of pores formed in the ceramic material constituting the base material 3.

Furthermore, convex scale 5 as a cooking guide, the thermal expansion coefficient is formed by baking a glass paste using a glass flux is 4.5 × 10 ^-6 /℃~7.0×10 ^-6 / ℃ Yes. Therefore, the difference in thermal expansion between the glass flux and the ceramic material is small, and the convex scale 5 can be effectively prevented from peeling off from the glaze layer 4 in the inner pot.

Further, the convex scale 5 protrudes from the surface of the glaze layer 4 with a protruding height of 5 to 100 μm, so that it can be visually recognized as well as tactilely (by touching with the hand). You can also
Moreover, it can prevent more effectively that the convex scale 5 will peel from the glaze layer 4 in an inner pot by comprising the glass flux which comprises the convex scale 5 by the said composition.

  Therefore, according to the present example, the gas cooker inner pot 2 that is excellent in heat resistance and durability and can cook cooked rice such as rice deliciously can be formed. In the inner pot 2, the convex scale 5 serving as a standard for cooking rice can be formed while preventing peeling.

(Physical property test)
Next, various physical property tests of the convex scale 5 (inventions 1 to 4) formed by appropriately changing the composition of the glass paste (glass flux, organic binder and inorganic pigment) constituting the convex scale 5 are performed. It was. For comparison, various physical properties tests were also performed on convex scales (comparative products 1 and 2) formed with a glass paste having a conventional composition.

As various physical property tests, a tape peeling test, an abrasion test, an alkali resistance test, an acid resistance test, a detergent resistance test, a boiled juice test and a heat resistance test were performed.
In the tape peeling test, a commercially available transparent tape was affixed to the decorative surface (convex scale) and rubbed firmly with a nail or the like, and then peeled off at an angle of 45 °. And the thing which the convex scale did not peel was set as (circle), and the thing where the convex scale peeled off even if it was x.

  In the wear test, the decorative surface (convex scale) was worn by a PEI testing machine (PEI ABRASION (trade name) manufactured by KEYSTONE ELECTRIC CO, INC.) Based on ASTM C448. Further, in the convex scale after the end of wear, a height of 50% or more remains, and a mark that can recognize a character is indicated as ◯, and the other is indicated as ×.

  In the alkali resistance test, the convex scale in the inner pot for cooking rice was immersed for 24 hours in a 5% sodium hydroxide solution of pH = 13 ± 0.5 heated to 40 ° C. The decorative surface (convex scale) did not change or was slightly matted, and the one that was completely matted and peeled was marked with x.

In the acid resistance test, the convex scale in the inner pot for cooking rice was immersed for 24 hours in a 5% acetic acid solution of pH = 2.5 ± 0.5 heated to 40 ° C. And the thing which the decoration surface (convex scale) did not change was set to (circle), and what changed even a little was set to x.
In the detergent resistance test, the convex scale in the inner pot for cooking rice was immersed for 24 hours in a 0.15% neutral detergent solution having a pH of 6.5 ± 0.5 heated to 40 ° C. And the thing which the decoration surface (convex scale) did not change was set to (circle), and what changed even a little was set to x.

In the boiled-resistant test, the convex scales in the inner pot for cooking rice were immersed for 1000 hours in oden boiled soup heated to 70 ° C. and pH = 6 ± 0.5. And the thing which the decoration surface (convex scale) did not change was set to (circle), and what changed even a little was set to x.
In the heat resistance test, the decorative surface (convex scale) was held at 200 ° C. for 10 hours, and then sufficiently cooled, and the presence or absence of peeling when the tape was attached to the decorative surface and peeled was confirmed. And the thing which the decoration surface did not peel was made into (circle) and what peeled was made into x.

  Table 1 shows the composition and physical properties of the glass fluxes of the inventive products 1 to 4 and the comparative products 1 and 2, the mixed amount of the glass flux, the inorganic pigment and the organic binder, and the results of the above various physical property tests.

In the same table, good results (◯) were obtained for any of the physical properties tests for Inventions 1 to 4, whereas for the comparative products 1 and 2, a tape peeling test, an abrasion test and an alkali resistance test were obtained. In either case, good results were not obtained.
From the above results, it was found that good results in various physical property tests can be obtained by setting the glass flux to the composition shown in the above examples.

Explanatory drawing which shows the inner pot for rice cookers accommodated in the inner pot holding part of the rice cooker main body in an Example. Sectional drawing which shows the inner pot for rice cookers in an Example. Sectional drawing which shows the state which provided the glaze layer in the surface of the base material in the Example, and provided the convex scale on the surface of the glaze layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rice cooker main body 11 Inner pot holding | maintenance part 2 Inner pot for rice cookers 21 Inner peripheral surface 3 Base material 4 Glaze layer 5 Convex scale

Claims (3)

In the rice cooker inner pot accommodated in the inner pot holding part of the rice cooker body,
The inner pot is formed by coating the surface of a container-shaped base material with a glaze layer, and the base material and the glaze layer are both made of a ceramic material,
The surface of the glaze layer on the inner peripheral surface of the inner pot is provided with a convex scale serving as a standard for cooking rice,
The convex scale is formed with a protruding height of 5 to 100 μm by baking a glass paste,
The glass paste is a mixture of glass flux, organic binder, and inorganic pigment,
The glass flux, the thermal expansion coefficient of ^{4.5 × 10 -6 /℃~7.0×10 -6 / ℃} , the SiO ₂ 42-67 wt%, 5 to 10 weight Al ₂ O ₃ %, B ₂ O ₃ and 18 to 23 wt%, MgO, CaO, 1 or 2 or more in total 2-5% by weight selected from the group of SrO and _{BaO, Li 2 O, Na 2} O and K ₂ An inner pot for a rice cooker comprising 5 to 10% by weight of a total of one or more selected from the group of O and 3 to 10% by weight of ZrO ₂ . According to claim 1, said substrate, water absorption with a coefficient of thermal expansion of 1.0 × 10 ^-6 /℃~3.0×10 ^-6 / ℃ is 2.0 to 8.0%,
The glaze layer, rice dexterity thermal expansion coefficient is equal to or greater than the base material, and is the thermal expansion coefficient of 2.0 × 10 ^-6 /℃~5.0×10 ^-6 / ℃ Inner pot. The ceramic material constituting the substrate according to claim 1 or 2, comprising one or more of β-spodumene, β-eucryptite and cordierite, mullite and quartz,
The ceramic material constituting the glaze layer contains one or more of β-spodumene, β-eucryptite and cordierite, and mullite, quartz, boron-based glass and an inorganic pigment. An inner pot for rice cookers.

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