JP3773564B2 - Catalyst film and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst film having oil-fat purifying performance and deodorizing performance and a method for producing the same, and is applied to a self-cleaning film used for cooking utensils such as a microwave oven.
[0002]
[Prior art]
Conventionally, as a catalyst film to obtain a self-cleaning effect (the effect of decomposing and purifying oils and odors adhering to the surface of the cooking chamber such as a microwave oven in an oven or other cooking appliance) There is one disclosed in Japanese Patent No. 7-4533.
[0003]
This catalyst film is formed by using an undercoat layer such as a heat-resistant paint such as a silicone resin, a self-cleaning paint and a heat-resistant adhesive, and a solvent containing an oxidation catalyst or a mixture of an oxidation catalyst and a polymerization inhibitor. After applying the top coat to the surface of the wet undercoat layer, forming the top coat layer, firing is performed to diffuse the oxidation catalyst and polymerization inhibitor at the interface between the undercoat layer and the top coat layer. The catalyst layer has a cross section in which the catalyst content gradually increases from the bottom to the top. As a result, oxidation catalyst and polymerization inhibitor particles are exposed on the surface of the coating layer, and the contact area between the particles and oil or the like adhering to the wall surface of the heating chamber is increased, thereby obtaining an excellent self-cleaning effect. It was.
[0004]
[Problems to be solved by the invention]
However, while the service life of cooking utensils such as a microwave oven is about 10 years, the conventional catalyst film can maintain a good self-cleaning effect for about 3 to 5 years. It was scarce.
[0005]
In addition, technologies that satisfy these demands are well established in response to demands such as higher deodorization performance, thinner film thickness, and smooth finish on the surface of the coating. Not.
[0006]
In view of the above, an object of the present invention is to provide a catalyst film that can maintain a good self-cleaning effect for a long period of time, and that can further improve deodorization performance, have a thin film thickness, and have a smooth finished skin, and a method for producing the same.
[0007]
[Means for Solving the Problems]
The problem-solving means of the present invention has a cross section in which the catalyst content gradually increases from the lowermost part to the uppermost part of the coating layer, and in the undercoat, an oxidation catalyst, a polymerization inhibitor, and an absorbent that absorbs oils and fats and odors Is used, and an overcoating with an oxidation catalyst is used for the overcoating.
[0008]
In addition, as a synthetic zeolite having hydrophobicity as the absorbent for the undercoat paint, the thickness of the film is reduced, and by adding a photocatalyst that promotes the function of the catalyst by irradiating the topcoat paint with ultraviolet rays, The deodorization performance is improved. By providing a primer layer between the coating layer and the metal base material, oxidative corrosion of the base material is suppressed. By making the film thickness of the undercoat 130 to 140 μm, the film thickness of the topcoat 20 to 30 μm, and the average particle diameter of both the undercoat and the overcoat or each catalyst of the overcoat about 25 μm, the film thickness is reduced and smoothed. Achieves a finished skin.
[0009]
In addition, as a method for producing a catalyst film, an undercoat is prepared by applying an undercoat paint containing an oxidation catalyst, a polymerization inhibitor, and an absorbent for absorbing fats and odors to a base material in a resin solution obtained by dissolving a heat-resistant resin in a solvent. A layer is formed, and a top coating layer in which an oxidation catalyst or a mixture of an oxidation catalyst and a photocatalyst is mixed in a solvent is applied to the surface of the undercoat layer in a wet state to form a top coating layer, and then firing is performed. Thereby, in the undercoat layer, the oxidation catalyst, the polymerization inhibitor, and the absorbent of the undercoat paint move to the surface of the undercoat layer by the solvent of the overcoat paint, and the upper layer portion becomes a catalyst-rich state. In the topcoat layer, the oxidation catalyst or the like diffuses at the interface between the basecoat layer and the topcoat layer due to the solvent, and the catalyst concentration on the surface increases. Therefore, it has a cross-section with a gradient concentration distribution in which the catalyst content increases from the lowermost part to the uppermost part of the coating layer, and oil and fat and odor adhering to the surface of the catalytic coating can be efficiently decomposed and purified.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment which formed the catalyst film of this invention in the wall surface of the heating chamber in a microwave oven is described.
[0011]
As shown in FIGS. 2 and 3, the microwave oven includes a range body 1 and a door 2 that is supported by the range body 1 so as to be freely opened and closed. An inner box 3 is fitted into the range body 1, and the inner box 3 includes left and right side plates 4 a and 4 b, a top plate 4 c, a bottom plate 4 d, a back plate 4 e, a food input and display panel. 5 and a frame-shaped front plate 4f having a fitting opening. The door 2 includes a frame plate 6 and a glass window 7 fitted in the frame plate 6. And the part enclosed by the inner box 3 and the door 2 is made into the heating chamber 8 which heats and cooks a foodstuff.
[0012]
Further, the top plate 4c is provided with a high-temperature heat irradiation hole 9 for introducing heat from a heater (not shown) disposed on the back side of the top plate 4c into the heating chamber 8. Further, one side plate 4 a is provided with an ultraviolet irradiation window 10 for introducing ultraviolet rays from an ultraviolet irradiation lamp (not shown) arranged on the back side of the side plate 4 a into the heating chamber 8.
[0013]
A catalyst film for obtaining a self-cleaning effect is formed on the wall surface of the heating chamber 8, that is, the surface of the inner box 3 and the door 2 on the heating chamber 8 side. In addition, it is not necessary to form a catalyst film on the part where the oils and fats and the odor component are less attached, for example, the bottom plate 4d of the inner box 3 or the like.
[0014]
Here, the catalyst film will be described in detail. As shown in FIG. 1, the catalyst film includes a primer layer 20 formed by applying a primer paint to a wall surface of a heating chamber 8 made of SUS430 (hereinafter referred to as a base material 11), and the primer layer 20. The coating layer is formed by applying an undercoating material to the surface and further applying an overcoating material.
[0015]
The primer coating used for forming the primer layer 20 is obtained by adding 20% leafing (purified) type aluminum powder to a resin solution obtained by dissolving methylphenyl silicone resin in an organic solvent. When a metal such as SUS is used as the base material 11, red rust occurs due to adhesion of salt water due to the oxidizing power of the catalyst in the catalyst film, which deteriorates appearance and causes adhesion of dirt, film peeling, etc. Although there is a possibility that it may lead to perforation due to corrosion, the formation of the primer layer 20 suppresses the oxidative corrosion of the base material 11 and solves the above-mentioned problems. Further, the primer layer 20 is also good against the boiling water resistance of the catalyst film.
[0016]
The undercoat used for the undercoat is composed of a resin solution Y obtained by dissolving a heat-resistant resin such as methylphenyl silicone resin in an organic solvent X such as toluene, normal butanol, isopropyl alcohol, and butyl cellosolve as a binder, and an oxidation catalyst A as a main catalyst. In addition, a polymerization inhibitor B that prevents fats and oils from being oxidized and cured in a resinous state, and an absorbent C that absorbs fats and oils and odors are added and blended.
[0017]
As the oxidation catalyst A, manganese dioxide powder may be used, and a small amount of platinum powder or alumina fine particle powder having a platinum content of 0.1 to 0.5% may be used. As the polymerization inhibitor B, aluminum oxide powder is used, and as the absorbent C, synthetic zeolite powder is used.
[0018]
Here, the reason why the absorbent C is blended is that when a large amount of fats and odors are generated at one time, these cannot be decomposed and purified at once. What is necessary is just to set it as the film | membrane structure which decomposes | disassembles and purifies gradually, For this reason, the absorber C which absorbs fats and oils and an odor is mix | blended. Therefore, the oil purification performance and deodorization performance are improved, and a good self-cleaning effect can be maintained for a long time.
[0019]
The blending ratio of each substance constituting the undercoat paint is 20: 45: 15: 20 (weight ratio) of methylphenyl silicone resin solution Y: oxidation catalyst A: polymerization inhibitor B: absorbent C, It is set to an optimum blending ratio in order to exhibit oil purification performance and deodorization performance.
[0020]
The top coat used for the top coat is the same organic solvent X as the organic solvent used for the base coat, with manganese dioxide powder, which is the oxidation catalyst A used for the base coat, and a photocatalyst D that greatly improves the deodorizing performance. It is a blended one.
[0021]
As the photocatalyst D, an optical semiconductor titanium oxide powder is used, and the function of each catalyst is promoted by being activated by the ultraviolet rays irradiated to the heating chamber 8 from the ultraviolet irradiation window 10 of the microwave oven described above. Note that the wavelength of the ultraviolet rays irradiated to the heating chamber 8 is preferably about 400 nm having catalytic activity. Moreover, the irradiation of the ultraviolet rays to the heating chamber 8 may be performed when the operation is stopped after the end of cooking and heating. The wall surface of the heating chamber 8 is purified with the passage of time, and the wall surface is cleaned during the next cooking. It is possible to prevent the smell of cooking from being transferred to the food.
[0022]
In addition, in the top coating, the oxidation catalyst A is blended at 50% (weight ratio), that is, the catalyst is rich, and the photocatalyst D is blended at 5 to 10% (weight ratio). Let At this time, in order to improve the storage stability, it is made into a paint using an appropriate dispersant without applying a large shearing force during production.
[0023]
The primer layer 20, the undercoat, and the overcoat formed using each of the paints as described above have a thickness of about 5 to 10 μm for the primer layer 20 to ensure oil purification performance and deodorization performance. In this case, it is desirable that the thickness of the undercoat is thicker than that of the overcoat, and the undercoat is particularly set to 130 to 140 μm within the range of 100 to 300 μm, and the overcoat is particularly set to 20 to 30 μm within the range of 20 to 100 μm. Therefore, the total thickness of the undercoat and the topcoat is as thin as about 160 μm. The reason why the film thickness can be reduced without deteriorating the oil purification performance and deodorization performance is that a hydrophobic synthetic zeolite powder is used as the absorbent C in the undercoat paint.
[0024]
Further, the average particle diameter of each catalyst contained in each paint is generally about 35 μm, whereas it is set to about 25 μm. As a result, the finished skin on the surface of the catalyst film can be made smooth and smooth, and the appearance can be improved. Moreover, even if the thickness is reduced, the finished skin can be maintained in a smooth state, and the oil purification performance and deodorization performance are not deteriorated. Even if only the oxidation catalyst A of the top coat is set to have an average particle size of about 25 μm, the same effect as described above can be obtained.
[0025]
Next, the manufacturing method of a catalyst film is explained in full detail. First, the primer layer 20 is formed by applying a primer coating to the surface of a clean base material 11 free from rust and dirt. Then, the undercoat paint is applied on the primer layer 20 to form the undercoat layer 21. Here, the undercoat layer 21 alone can improve the oil purification performance and the deodorizing performance, and the film thickness can be thin and the finished skin can be made smooth, but the catalyst-rich topcoat layer 22 is formed. Thus, the catalyst concentration is increased to obtain a further synergistic effect.
[0026]
Therefore, as shown in FIG. 4, the top coat is applied to the surface of the wet undercoat layer 21 to form the top coat layer 22 and then fired. At this time, in the undercoat layer 21, the oxidation catalyst A, the polymerization inhibitor B, and the absorbent C of the undercoat paint move to the surface of the undercoat layer 21 by the organic solvent X of the overcoat paint, and the upper layer portion is rich in the catalyst. It becomes a state. In the topcoat layer 22, the oxidation catalyst A and the photocatalyst D are diffused at the boundary surface 30 between the undercoat layer 21 and the topcoat layer 22 by the organic solvent X, and the catalyst concentration on the surface is increased.
[0027]
As a result, as shown in FIG. 5, the base material 11 has a cross-section with a gradient concentration distribution in which the catalyst content increases from the bottom to the top of the coating layer, and adheres to the surface of the catalyst coating. Oils and fats and odors can be efficiently decomposed and purified, and a good self-cleaning effect can be obtained. In addition, the catalyst film finally finished after curing after baking and drying is integrated as a coating layer without the boundary surface 30 between the undercoat layer 21 and the overcoat layer 22 before baking shown in FIG. ing.
[0028]
In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention. For example, a catalyst film may be formed on a wall other than the wall of the microwave oven heating chamber (for example, the front plate of the inner box, the door frame plate, the range body, etc.). Therefore, a catalytic coating using a photocatalyst as a main catalyst may be formed. Then, total self-cleaning of the whole microwave oven can be realized. In addition, when a catalyst film is formed on the air circulation path (duct) in the range body, it is possible to provide delicious food without odor transfer even when cooking different types of cooked food due to the deodorizing performance of the catalyst film. Furthermore, if the base material is made of a member that is not easily oxidized and corroded, the primer layer may not be formed.
[0029]
【Example】
Hereinafter, an experiment for confirming a good self-cleaning effect by the catalyst film will be described in detail. In the experiment, about 0.1 g of cooked beef broth was dropped on the test plate on which the catalyst film was formed and held in an electric furnace at 300 ° C. for 20 minutes as one cycle. The time when glossy oily resination occurred on the surface of the film was evaluated as the purification capacity limit. As a result, the conventional catalyst film reached the capacity limit in 3 cycles, whereas the catalyst film reached the capacity limit in 10 cycles or more. Accordingly, when converted into the service life (period in which the self-cleaning effect can be maintained), the conventional catalyst film has a service life of about 3 to 5 years based on the actual statistics, and thus the catalyst film has a service life of about 10 It will be ~ 15 years.
[0030]
On the other hand, in the experiment for confirming the deodorizing performance, a test piece made of stainless steel having a thickness of 0.6 mm and a size of 5 cm square on which about 210 μm of the above-mentioned catalyst film (assuming that the photocatalyst D is not included) was formed was 200 ml. It was put in a container, and 3 μl of a 30% aqueous solution of trimethylamine, which is a rotten odor of fish, was dropped into this container, and the concentration was measured by maintaining at 100 ° C. for 5 minutes and then at room temperature for 10 minutes. As a result, the trimethylamine concentration was about 12 to 22 ppm in the conventional catalyst film with respect to the blank of 900 ppm, and the deodorizing performance was improved by about 5 to 8 ppm in the catalyst film.
[0031]
Furthermore, in the case of a catalyst film in which photocatalyst D (photosemiconductor titanium oxide powder) is added and blended with the top coat, when the same deodorizing performance measurement as described above is performed, the trimethylamine concentration is about 3 to 5 ppm and the wavelength is about 400 nm. As a result, the deodorizing performance was remarkably improved by about 1-2 ppm.
[0032]
【The invention's effect】
As is clear from the above description, according to the invention of claim 1, since an absorbent is blended in the undercoat paint used for the undercoat, when a lot of oils and odors are generated at once, these are once absorbed by the absorbent. It can be gradually decomposed and purified, and the oil and fat purification performance and deodorization performance are improved as compared with the case of using only an oxidation catalyst and a polymerization inhibitor, and a good self-cleaning effect can be maintained for a long time.
[0033]
According to the invention of claim 2, since the absorbent is a synthetic zeolite having hydrophobicity, the thickness of the catalyst film can be reduced while maintaining the oil purification performance and the deodorizing performance.
[0034]
According to the invention of claim 3, since the photocatalyst is blended in the top coat used for the top coat, when a catalyst film is formed in a place where ultraviolet rays are irradiated, the photocatalyst is activated and promotes the function of each catalyst. Deodorizing performance can be improved significantly.
[0035]
According to the invention of claim 4, when a metal that is susceptible to oxidative corrosion is used as the base material, rust and the like are generated due to the oxidizing power of the catalyst and the appearance is deteriorated, and adhesion of dirt and peeling of the film occur. Although there is a possibility that it may lead to perforation due to local corrosion, the above problem can be solved by suppressing the oxidative corrosion of the base material by the primer layer.
[0036]
According to the invention of claim 5, even if the film thickness of the catalyst film is reduced, the finished skin on the surface of the catalyst film can be made into a smooth thin film without roughness, and the appearance is improved. In addition, the oil purification performance and deodorization performance are not deteriorated.
[0037]
According to the invention of claim 6, after the top coat is applied to the surface of the wet undercoat layer to form the top coat layer, firing is performed, so that each boundary surface between the undercoat layer and the top coat layer is subjected to firing. Since the catalyst content is changed by moving the catalyst, a catalyst film having a good self-cleaning effect with a cross section in which the catalyst content increases from the bottom to the top of the film layer is easily manufactured. be able to.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a catalyst film in an embodiment of the present invention. FIG. 2 is a perspective view of a microwave oven. FIG. 3 is a perspective view of an inner box. FIG. 4 is an enlarged cross-sectional view of the catalyst film before firing. Expanded cross-sectional view of the catalyst film after firing [Explanation of symbols]
11 Base material 20 Primer layer 21 Undercoat layer 22 Overcoat layer A Oxidation catalyst B Polymerization inhibitor C Absorbent D Photocatalyst X Solvent Y Resin solution

Claims (6)

A catalyst film that decomposes and purifies oils and fats and odors, and has a cross-section in which the catalyst content gradually increases from the bottom to the top of the film layer, and the undercoat has an oxidation catalyst, a polymerization inhibitor, and oils and odors. A catalyst film characterized by using an undercoating paint containing an absorbent that absorbs water and using an overcoating paint containing an oxidation catalyst for the overcoating.  2. The catalyst film according to claim 1, wherein the undercoat paint absorbent is a hydrophobic synthetic zeolite.  2. The catalyst film according to claim 1, wherein a photocatalyst that is activated by ultraviolet irradiation to promote the function of the catalyst is blended in the top coat.  4. The catalyst film according to claim 2, wherein a primer layer for suppressing oxidative corrosion of the base material is disposed between the film layer and the metal base material.  2. The thickness of the undercoat is 130 to 140 [mu] m, the thickness of the topcoat is 20 to 30 [mu] m, and the average particle size of both the undercoat and the topcoat or each catalyst of the topcoat is about 25 [mu] m. , 2 or 3 catalyst film. An undercoat layer is formed by applying an undercoat paint containing an oxidation catalyst, a polymerization inhibitor, and an absorbent that absorbs oils and odors to a resin solution in which a heat-resistant resin is dissolved in a solvent, and an oxidation catalyst or an oxidation catalyst is formed in the solvent. A top coating composition containing a mixture of a photocatalyst is applied to the surface of the undercoat layer in a wet state to form a top coat layer, and then baked, each at the boundary surface between the undercoat layer and the top coat layer. A method for producing a catalyst film, wherein the catalyst content is gradually increased from the lowermost part to the uppermost part of the film layer by moving the catalyst.

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