JPH1094484A - Cooking utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooking utensil of high cleanliness based on a new principle, having a capability of realizing the high cleanliness even in the case of versatile materials used for a substrate. SOLUTION: The cooking utensile (hot plate 1) has an optical semiconductor- contained layer formed on the surface of a cooking plate 2 in contact with food, and the surface of the layer becomes highly hydrophilic in response to an optical excitation effect. When the surface is highly hydrophilic, a hydrophilic contaminant (fat and oil or the like) does not adhere to the surface of the utensil in the presence of water. Also, a contaminant deposited without the presence of water can be washed away with water. On the other hand, a hydrophilic contaminant adheres to the surface of the utensil, but can be washed way with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to cooking utensils such as frying pans, bowls and hot plates. In particular, the present invention relates to a highly clean cooking utensil which is difficult to be stained or which is easily cleaned.

[0002]

2. Description of the Related Art Frying pans, hot plates and the like are available on the market where food is cooked with so-called Teflon processing. On the Teflon-treated surface, food is less likely to be scorched and dirt is easily removed during washing.

[0003]

However, there is an opinion that the frying pan processed with Teflon hardly averages the oil, and the taste of a dish using a small amount of oil such as meuniere is inferior to that of an iron plate frying pan. In addition, the cost increases and the weight increases with the Teflon processing. An object of the present invention is to provide a highly clean cooking utensil based on a new principle in which the above-mentioned drawbacks are improved.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, a cooking utensil of the present invention has an optical semiconductor-containing layer formed on a surface in contact with food.
It is characterized in that the surface of the layer exhibits a high degree of hydrophilicity.
Based on the principle described later in detail, the optical semiconductor-containing layer that has been photoexcited by ultraviolet irradiation or the like exhibits a high degree of hydrophilicity.
And if the surface is sufficiently hydrophilic, hydrophobic dirt (oil, fat, carbon black, soot, etc.) will not adhere to the cooking utensil surface in the presence of water. Also, with respect to dirt attached when water does not exist, dirt is removed by flowing water.
On the other hand, hydrophilic dirt (mud dirt, garbage, etc.) adheres to the cooking utensil surface, but the dirt is removed by flowing water.

The relationship between the optical semiconductor-containing layer and the hydrophilicity will be described. The present inventors have proposed PCT / JP96 / 0073.
In No. 3, the following findings were described. That is, when the optical semiconductor-containing layer is formed on the base material surface, the layer surface is found to exhibit a high degree of hydrophilicity of 10 ° or less in terms of a contact angle with water in response to optical excitation of the optical semiconductor. As a result, it has been found that effects such as improvement of anti-fog and improvement of visibility of transparent members such as glass, lens and mirror, improvement of water washability and rainfall washability of an article surface can be obtained.

[0006] This phenomenon is considered to proceed by the following mechanism. That is, when light having energy equal to or more than the energy gap between the upper end of the valence band and the lower end of the conduction band of the optical semiconductor is irradiated on the optical semiconductor, the electrons in the valence band of the optical semiconductor are excited to cause conduction electrons and holes. Are formed, and by either or both actions, polarities are probably imparted to the surface, and polar components such as water and hydroxyl groups are collected. Then, one or both of the conduction electrons and holes and the above-mentioned polar component cooperate with each other to cut a chemical bond between the surface and the contaminant chemically adsorbed on the surface, and to cause the surface to absorb chemically adsorbed water. Is adsorbed, and a physically adsorbed water layer is formed thereon. Further, once the surface of the member is highly hydrophilized, the hydrophilicity of the surface is maintained for a certain period even if the member is kept in a dark place.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hydrophilicity is a property that is easy to conform to when water is dropped on a surface.
It refers to a state of less than 0 °. The high hydrophilicity in the present invention refers to the property that the surface is very easy to conform when water is dropped, and rather forms a water film without forming a water droplet. More specifically, the water wetting angle (water (A contact angle with) is 10 ° or less, preferably 5 ° or less.

[0008] An optical semiconductor is formed by irradiating light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction electron band and the valence band of the crystal. A substance capable of generating conduction electrons and holes by excitation of electrons (photoexcitation), such as anatase-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, and tungsten trioxide. Ferric oxide, strontium titanate and the like can be suitably used.

Light sources used for optical excitation of optical semiconductors include:
Indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp, the sun, and a light source in which light from the light source is guided by a low-loss fiber can be suitably used.

It is desirable that the optical semiconductor-containing layer contains at least one of silica, solid superacid, and silicone. When silica and solid superacid are contained,
It tends to exhibit a high degree of hydrophilicity at lower excitation light illuminance, and can maintain that state for a considerably long time. Even if silicone is contained, at least a part of the organic group bonded to the silicon atom in the silicone is replaced with a hydroxyl group by photoexcitation of the optical semiconductor. Once substituted with a hydroxyl group, as in the case of silica addition, it tends to exhibit a high degree of hydrophilicity with low excitation light illuminance and can maintain that state for a considerably long time.

Here, the superacid is a Hammett acidity function H
A strong acid containing a solid oxide satisfying o ≦ −11.93 as a component, specifically, sulfuric acid-supported Al ₂ O ₃ , sulfuric acid-supported T
iO ₂ , ZrO ₂ supported on sulfuric acid, Fe ₂ O ₃ supported on sulfuric acid, SiO ₂ supported on sulfuric acid, HfO ₂ supported on sulfuric acid, TiO ₂ / WO ₃ ,
WO ₃ / SnO ₂ , WO ₃ / ZrO ₂ , WO ₃ / Fe ₂
O ₃ , SiO ₂ · Al ₂ O _{3 and the} like can be suitably used.

As the silicone, polyorganosiloxanes can be generally used. For example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane,
Ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyl Dipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane,
Phenylmethyldipropoxysilane, phenylmethyldibutoxysilane, γ-glycidoxypropyltrimethoxysilane, and their hydrolysates, those partially hydrolyzed after hydrolysis, their mixtures, etc. as precursors, if necessary Hydrolysis, dehydration-condensation polymerization, etc. can be suitably used.

The thickness of the optical semiconductor-containing layer is preferably set to 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the optical semiconductor-containing layer becomes substantially transparent. Further, the thickness of the optical semiconductor-containing layer is set to 0.2 μm.
m or less is more preferable. Then, color formation of the layer due to light interference can be prevented. Further, the thinner the optical semiconductor-containing layer, the higher its transparency. Furthermore, the thinner the film, the better the wear resistance of the layer. On the surface of the surface layer, a protective layer or other functional film of silica, alumina, silicone, solid superacid or the like which can be hydrophilized and which can be hydrophilized may be further provided.

The optical semiconductor-containing layer includes Ag, Cu, Z
A metal such as n can be added. The layer to which the metal is added can kill bacteria adhering to the surface even in a dark place. In addition, this layer inhibits the growth of microorganisms such as molds, algae and moss. Therefore, adhesion of dirt due to microorganisms is suppressed. A for optical semiconductor containing layer
To dope g, Cu, or Zn, a soluble salt of these metals can be added to the suspension of optical semiconductor particles and the resulting solution used to form an optical semiconductor coating. Alternatively, a soluble salt of these metals may be applied after the formation of the optical semiconductor coating, and photoreduction precipitation may be performed by irradiation with light.

[0015] Pt, Pd, R
A platinum group metal such as u, Rh, Os, Ir can be added. The layer to which the metal is added can enhance the oxidation reaction activity of the optical semiconductor by the optical semiconductor action,
The effect of decomposing and removing dirt attached to the surface of the layer, deodorizing and purifying indoor air, and decomposing and purifying pollutants contained in outdoor air are improved. The addition method can be based on the above-described photoreduction precipitation or addition of a soluble salt.

The material constituting the base of the cooking utensil of the present invention is a metal material; iron, stainless steel, aluminum alloy, titanium alloy, FRP; glass fiber reinforced, carbon fiber reinforced, polyamide fiber reinforced, epoxy type, unsaturated polyester type. , Plastics; polypropylene, urethane, ABS,
Nylon, acrylic, polycarbonate, coating materials; including polyethylene glass.

Here, the cooking utensil is made of Fe, Ni, Co.
When there is a substrate made of a metal material containing at least one of the above, the optical semiconductor-containing layer is formed on the surface of the substrate via a layer for preventing diffusion of the metal atoms.

According to the experiments of the present inventors, it has been found that when Co, Ni, and Fe are added to the surface layer containing the optical semiconductor, the hydrophilicity of the optical semiconductor by photoexcitation is significantly reduced. . Therefore, by providing a layer that prevents diffusion of Co, Ni, and Fe atoms into the surface layer, the surface layer containing the optical semiconductor is not affected by Co, Ni, and Fe atoms, and at least Co, Ni, and Fe atoms are not affected. Even when it is fixed on a base material containing one kind, the hydrophilizing action of the photo-semiconductor by photoexcitation is sufficiently exerted, and therefore, the effects of improving the water washability and rainfall washability of the article surface are sufficiently exhibited. Become like

The substrate containing at least one of Co, Ni and Fe atoms refers to, for example, a stainless steel substrate, carbon steel, cast iron, casting, ferromagnetic material and the like. The layer for preventing the diffusion of Co, Ni and Fe is, for example, silica, silicone resin, acrylic resin,
A transparent material such as a silicate compound such as water glass can be suitably used.

Further, a coloring material may be used for the layer for preventing the diffusion of Co, Ni, and Fe, and this layer may have a design property. In that case, glaze; C such as Ag or Pt
Materials such as colored metals other than o, Ni, and Fe can be suitably used. The thickness of the layer for preventing the diffusion of Co, Ni and Fe is preferably 0.02 μm or more. Then, diffusion of Co, Ni, and Fe from the base material to the surface layer can be effectively prevented.

Next, a method for forming the surface layer will be described. First, a manufacturing method in the case where the surface layer is made of only an optical semiconductor will be described with reference to an example in which the optical semiconductor is an anatase type titanium oxide. In this case, there are roughly three methods. One method is a sol coating and firing method, the other method is an organic titanate method, and the other method is an electron beam evaporation method. (1) Sol-coating and firing method Anatase-type titanium oxide sol is applied to the surface of a substrate by a method such as spray coating, dip coating, flow coating, spin coating, or roll coating, and then fired.

(2) Organic Titanate Method Titanium alkoxides (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), titanium acetates, titanium chelates and other organic titanates can be used as hydrolysis inhibitors (hydrochloric acid, ethylamine, etc.). After diluting with a non-aqueous solvent such as alcohol (ethanol, propanol, butanol, etc.), partially or completely proceeding the hydrolysis, the mixture is spray-coated, Apply by coating method, flow coating method, spin coating method, roll coating method, etc.
dry. By drying, the hydrolysis of the organic titanate is completed to produce titanium hydroxide, and a layer of amorphous titanium oxide is formed on the surface of the base material by dehydration-condensation polymerization of the titanium hydroxide. Thereafter, the amorphous titanium oxide is calcined at a temperature equal to or higher than the crystallization temperature of anatase to cause a phase transition from the amorphous titanium oxide to the anatase titanium oxide.

(3) Electron Beam Evaporation Method An amorphous titanium oxide layer is formed on the surface of a substrate by irradiating an electron beam to a titanium oxide target. After that, firing at a temperature higher than the crystallization temperature of anatase,
Phase transition of amorphous titanium oxide to anatase titanium oxide.

Next, the case where the surface layer is made of an optical semiconductor and silica will be described with reference to the case where the optical semiconductor is an anatase type titanium oxide. In this case, for example, there are the following three methods. One method is a sol coating and firing method, the other is an organic titanate method, and the other is a tetrafunctional silane method. (1) Sol coating and baking method A mixture of anatase-type titanium oxide sol and silica sol is applied to the substrate surface by a method such as a spray coating method, a dip coating method, a flow coating method, a spin coating method, and a roll coating method, and then fired. I do.

(2) Organic titanate method Titanium alkoxide (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), an organic titanate such as titanium acetate, titanium chelate and the like, and a hydrolysis inhibitor (hydrochloric acid, ethylamine, etc.) And silica sol, and add alcohol (ethanol,
After diluting with a non-aqueous solvent such as propanol, butanol, etc., and then allowing the hydrolysis to proceed partially or completely, the mixture is spray-coated, dip-coated, flow-coated,
It is applied by a method such as spin coating or roll coating and dried. By drying, the hydrolysis of the organic titanate is completed to produce titanium hydroxide, and a layer of amorphous titanium oxide is formed on the surface of the base material by dehydration-condensation polymerization of the titanium hydroxide. Thereafter, the amorphous titanium oxide is calcined at a temperature equal to or higher than the crystallization temperature of anatase to cause a phase transition from the amorphous titanium oxide to the anatase titanium oxide.

(3) Tetrafunctional silane method A mixture of tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.) and an anatase type titanium oxide sol is spray-coated on the surface of a substrate, After coating by a dip coating method, a flow coating method, a spin coating method, a roll coating method, or the like, and hydrolyzing as needed to form a silanol, the silanol is subjected to dehydration polycondensation by a method such as heating.

Next, the case where the surface layer is made of an optical semiconductor and a solid acid will be described, taking the case where the optical semiconductor is an anatase type titanium oxide and the solid acid is TiO ₂ / WO ₃ as an example. In this case, a method of mixing an ammonia solution of tungstic acid and an anatase-type titanium oxide sol and, if necessary, diluting the mixture with a diluting liquid (water, ethanol, etc.) on the surface of the base material by spray coating, dip coating, or the like. It is applied by a method such as a flow coating method, a spin coating method, and a roll coating method, and is baked.

Next, the case where the surface layer is made of an optical semiconductor and silicone will be described, taking the case where the optical semiconductor is an anatase type titanium oxide as an example. The method in this case is to mix a coating of uncured or partially cured silicone or a silicone precursor with an anatase-type titanium oxide sol, hydrolyze the silicone precursor if necessary, and then mix the mixture. Spray coating method, dip coating method, flow coating method,
It is applied by a method such as a spin coating method or a roll coating method, and a hydrolyzate of a silicone precursor is subjected to dehydration polycondensation by a method such as heating to form a surface layer composed of anatase type titanium oxide particles and silicone. . In the formed surface layer, at least a part of the organic group bonded to the silicon atom in the silicone molecule is replaced with a hydroxyl group by photoexcitation of the anatase type titanium oxide by irradiation with light including ultraviolet rays, and further thereon. A physisorbed water layer is formed and exhibits a high degree of hydrophilicity. Here, the aforementioned substances can be used as the silicone precursor.

When the optical semiconductor-containing layer is formed on the surface of the transparent member, the optical semiconductor-containing layer preferably has a refractive index not so high as compared with the substrate. Preferably, the refractive index of the optical semiconductor-containing layer is 2 or less. Then, the reflection of light at the interface between the base material and the optical semiconductor-containing layer and at the interface between the optical semiconductor-containing layer and air can be suppressed. In order to reduce the refractive index of the optical semiconductor-containing layer to 2 or less, 2
A substance having the following refractive index is used, or when the optical semiconductor has a refractive index of 2 or more, another substance having a refractive index of 2 or less is added to the optical semiconductor-containing layer. As an optical semiconductor having a refractive index of 2 or less, tin oxide (refractive index: 1.9) or the like can be used. Optical semiconductors having a refractive index of 2 or more include anatase-type titanium oxide (refractive index: 2.5) and rutile-type titanium oxide (refractive index: 2.7). Substances such as calcium carbonate (refractive index 1.
6), calcium hydroxide (refractive index 1.6), magnesium carbonate (refractive index 1.5), strontium carbonate (refractive index 1.5), dolomite (refractive index 1.7), calcium fluoride (refractive index 1) .4), magnesium fluoride (refractive index: 1.4), silica (refractive index: 1.5), alumina (refractive index: 1.6), silica sand (refractive index: 1.6), montmorillonite (refractive index: 1.5) ), Kaolin (refractive index 1.6), sericite (refractive index 1.6), zeolite (refractive index 1.5),
What is necessary is just to add tin oxide (refractive index 1.9) etc. to an optical semiconductor containing layer.

When the base material is a glass containing an alkali network modifying ion such as sodium (soda lime glass, side-by-side glass, etc.), an intermediate layer such as silica is formed between the base material and the optical semiconductor-containing layer. You may. This prevents the alkali network modifying ions from diffusing from the base material into the optical semiconductor-containing layer during firing, so that the optical semiconductor function is better exhibited.

Examples of the cooking utensil of the present invention include the following. Frying pans, hot plates, bowls, cutting boards, kitchen knives, pots, kettles, iron plates for okonomiyaki and teppanyaki.

[0032]

Embodiments of the present invention will be described below. FIG.
FIG. 3 is a view showing a hot plate according to one embodiment of the present invention. In the drawing, 1 is a rectangular frame, and 2 is a flat cooking plate provided inside the frame 1 and formed by casting a metal having good heat conductivity. Reference numeral 3 denotes a sheath heater embedded in the cooking plate 2 in a loop shape.

Reference numeral 8 denotes a temperature sensor provided at the center of the back surface of the cooking plate 2, 9 denotes a set temperature indicator of the cooking plate 2 provided on one side of the frame 1, 10 denotes a temperature setting button, and 11 denotes a changeover switch 13. Button.

An optical semiconductor-containing layer is formed on the upper surface and side surfaces of the cooking plate 2 and the frame 1 by the following method.

86 parts by weight of an ethanol solvent for a cooking utensil having an iron plate as a base, 6 parts by weight of tetraethoxysilane (Wako Pure Chemical Industries), 6 parts by weight of pure water, and 2 parts by weight of 36% hydrochloric acid as a hydrolysis inhibitor for tetraethoxysilane A part was added and mixed to prepare a silica coating solution. This solution was applied to the surface of a 10 cm square iron plate by a flow coating method, and dried at a temperature of 80 ° C. With drying, tetraethoxysilane undergoes hydrolysis to become silanol first, followed by dehydration condensation polymerization of silanol,
A thin film of amorphous silica was formed on the surface of the iron plate.

Next, tetraethoxytitanium (Merc)
k) A titanium oxide coating solution is prepared by adding 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor to a mixture of 1 part by weight and 9 parts by weight of ethanol, and applying the solution to the above-mentioned amorphous silica thin film by dry air. It was applied by a flow coating method in the inside. The coating amount is 45 μg / cm in terms of titanium oxide
^{And 2} . Since the rate of hydrolysis of tetraethoxytitanium is extremely fast, part of the tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide began to form.

Next, the iron plate is heated at about 150 ° C. for 1 to 10 minutes.
, The hydrolysis of tetraethoxytitanium was completed, and the produced titanium hydroxide was subjected to dehydration-condensation polymerization to obtain an iron plate coated with amorphous titanium oxide. This sample was fired at a temperature of 500 ° C. to crystallize the amorphous titanium oxide into anatase type titanium oxide to obtain a sample having an optical semiconductor-containing layer.

The following three evaluations were performed on this sample and an untreated iron plate for comparison. (1) Evaluation of surface hydrophilicity recovery performance upon irradiation with ultraviolet light After oleic acid was applied to the sample surface, rubbed with a neutral detergent (mama lemon), rinsed with tap water and distilled water, and then dried at 50 ° C. with a dryer at 30 ° C. By intentionally drying the surface, the surface is intentionally contaminated and then the BLB fluorescent lamp is turned on at 0.5 mW / cm ² for 5 minutes.
Irradiation was performed for a period of time, and the change in the contact angle of the sample surface with water was examined.
As a result, in the iron plate, the contact angle with water after the contamination and after the irradiation with the BLB fluorescent lamp was both 70 °, which was not changed. On the other hand, in the sample on which the optical semiconductor-containing layer was formed, 5% after the contamination.
The contact angle with water, which was 0 °, was highly hydrophilized to almost 0 ° after irradiation with the BLB fluorescent lamp.

(2) Washing effect of oleic acid in water immersion Oleic acid was applied to the sample surface used in the test of (1), and the sample was placed in a water filled water tank while the sample surface was kept in a horizontal posture. Immersion. as a result. In the iron plate, oleic acid remained attached to the surface of the sample, and even when lightly rubbed with water, the oil only extended on the sample, whereas in the sample on which the optical semiconductor-containing layer was formed, oleic acid was Curls into oil droplets, rubbing it lightly with your finger in water,
It was released from the sample surface and surfaced.

(3) Effect of Cleaning of Hydrophobic Soil Next, a powder mixture consisting of 1 part by weight of hydrophobic carbon black and 1 part by weight of hydrophilic carbon black was added in an amount of 1.05 g /
A slurry suspended in water at the concentration of liter was prepared.
The sample inclined at 45 ° and the untreated iron plate sample were allowed to flow 150 ml of the slurry and dried for 15 minutes, and then dried with 150 ml of distilled water and dried for 15 minutes. This cycle was repeated 25 times. The color difference change before and after the test,
It measured using the color difference meter (Tokyo Denshoku). The color difference was represented by ΔE * according to Japanese Industrial Standard (JIS) H0201. As a result, the color difference change of the iron plate was as large as 20, whereas the color difference change of the sample was only 0.6.

[0041]

As is apparent from the above description, the present invention can provide a highly clean cooking appliance even when the base material is various. In addition, it is possible to provide a cooking appliance having extremely significant performance for cooking appliances such as antibacterial properties and oxidative decomposition of attached dirt.

[Brief description of the drawings]

FIG. 1 is a view showing a hot plate according to one embodiment of the present invention.

[Explanation of symbols]

1 frame, 2 cooking plate 3 sheathed heater 8 temperature sensor 9 set temperature display 10 temperature setting button 11 switch button 13 switch

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[Procedure amendment]

[Submission date] October 3, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

Claims (6)

[Claims] 1. A cooking utensil, wherein an optical semiconductor-containing layer is formed on a surface in contact with food, and the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor. 2. The cooking utensil according to claim 1, wherein said optical semiconductor-containing layer further contains at least one of silica, solid superacid, and silicone. 3. The method according to claim 1, wherein the degree of hydrophilicity is 10 ° or less in terms of a contact angle with water.
Cookware as described. 4. The cooking utensil according to claim 1, wherein the degree of hydrophilicity is 5 ° or less in terms of a contact angle with water. 5. The cooking utensil has a base made of a metal material containing at least one of Fe, Ni, and Co, and the optical semiconductor-containing layer causes diffusion of atoms of the metal on a surface of the base. The cooking utensil according to any one of claims 1 to 4, wherein the cooking utensil is formed via a layer for preventing the cooking utensil. 6. The optical semiconductor-containing layer is made of Ag, Cu, Zn.
The cooking utensil according to any one of claims 1 to 7, comprising at least one of the following.