JP3031937U - In-vessel deodorizing device for food storage - Google Patents

Abstract

(57) [Summary] [Structure] The deodorizing device consists of a condenser lens and a porous material supporting titanium (IV) oxide, and if necessary, an air circulation fan. The light flux of the condenser lens hits the porous material. It is an in-container deodorizing device for a self-regenerating food storage device that utilizes photocatalytic properties and is installed in the same manner. Further, the titanium oxide (IV) is preferably one having an anatase type crystal system, and the condensing lens is preferably a molded body made of translucent plastic.
Furthermore, a structure in which this porous material is installed within the focal length of the condenser lens is preferable. [Effect] The in-vessel deodorizing device of the food storage device of the present invention uses a porous material carrying titanium oxide (IV) having photocatalytic properties,
It has the function of irradiating light focused by a condenser lens and adsorbing and decomposing odorous gases such as trace amounts of amines, ammonia, mercaptans, aldehydes and lower carboxylic acids present in the storage due to the action of a photocatalyst, At the same time, the adsorption function is regenerated, so that it can be used semipermanently. This is the main feature of the in-vessel deodorizing device of this food storage device.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates to a deodorizing device that decomposes and removes offensive odor components in food storage. More specifically, it uses a photocatalyst having a self-regenerating function as a deodorant and decomposes malodorous components by utilizing the oxidation catalytic property of titanium oxide by visible light and near-ultraviolet light. It has a characteristic that it can adsorb and decompose malodorous components such as ammonia, mercaptans, aldehydes and lower carboxylic acids, and can regenerate the deodorizing function.

[0002]

[Prior art]

 The components of malodorous gas existing in food storages such as commercial refrigerators, storages, and showcases are mainly ammonia, amines, mercaptans, lower aldehydes, and lower carboxylic acids generated from foods. There are many known methods for removing these malodors, but the most widely used method is to use an adsorbent such as activated carbon. However, it is difficult to remove all these malodorous gases only with an adsorbent such as activated carbon.

Further, so-called additive removable odorant in which an alkaline substance or an acidic substance is carried on an adsorbent such as activated carbon is effective for removing many malodorous components, but is not effective for all malodorous gases. There is also a drawback that the life of the deodorant is shortened. In addition, a method of using a catalyst substance supported on an adsorbent is also known, but harmful odorous substances are often produced by side reactions such as the formation of disulfides from mercaptans.

In addition, there is known a method in which the deodorizing function is regenerated by completely oxidizing and decomposing the adsorbed malodorous component to prolong the life of the adsorbent semipermanently. Most of these deodorants have a composition in which a noble metal compound is supported on an adsorbent, and after adsorbing a malodorous gas, it is heated to 100 ° C or more to oxidize and decompose the malodorous component. However, since such deodorant needs to be heated, it requires a heat source (energy). Moreover, activated carbon cannot be used due to the high temperature, and there is a disadvantage that a non-combustible adsorbent having a relatively small adsorption capacity must be used.

By the way, there is a photocatalyst typified by titanium oxide that can be regenerated at room temperature without requiring heating to a high temperature to restore the function of the oxidation catalyst. By irradiating titanium oxide with light rays, especially near ultraviolet rays, it is possible to decompose and regenerate the malodorous gas adsorbed at room temperature.

Examples of applying a photocatalyst are as follows. Japanese Patent Laid-Open No. 01-234729 and Japanese Patent Publication No. 01-231926 disclose an example in which a photocatalyst having titanium oxide supported on activated carbon is used in an air conditioner or an air cleaner. However, neither of the publications exemplifies the specific malodorous gas to be removed, nor is there any test example showing that the malodorous gas can be actually removed.

[0007]

[Problems to be solved by the device]

 The present invention is designed to absorb a small amount of malodorous gas existing in the container of a food storage container such as amines, ammonia, mercaptans, aldehydes and lower carboxylic acids with an adsorbent, and then emit light from a fluorescent lamp or the like. By irradiating with, the adsorbed malodorous component is oxidized and decomposed to regenerate the deodorizing function, and the in-container deodorizing device of the self-regenerating type food storage device that can be used semipermanently is provided.

[0008]

[Means for Solving the Problems]

 The present inventor paid attention to the photocatalyst as a deodorant having a regeneration function, and examined it based on the literature described in the section of the conventional art. As a result, it was confirmed that basic gas and acidic gas could not be sufficiently removed even by irradiating a fluorescent lamp only by supporting titanium oxide on the surface of an adsorbent such as activated carbon. Japanese Unexamined Patent Publication No. 06-170220 discloses an example of using a photocatalyst in which titanium oxide is supported on the outer surface of activated carbon, but an example is shown in which neutral acetaldehyde is irradiated and decomposed by an ultraviolet lamp. It is only there. The acetaldehyde illustrated therein is a kind of compound that is easily decomposed by a photocatalyst.

On the other hand, in order to decompose a wide range of malodorous substances including acidic gas and basic gas only with the light of a fluorescent lamp, titanium oxide-supporting activated carbon is still insufficient. Japanese Unexamined Patent Application Publication No. 07-24256 discloses an example of a photocatalyst prepared by supporting titanium oxide on the surface of acid- and alkali-impregnated activated carbon, but the gas actually targeted for removal is neutral. Acetaldehyde, toluene and basic ammonia. When activated carbon impregnated with this acid and alkali is used, the effect of removing ammonia is particularly high, but it is difficult to maintain the deodorizing effect for a long period of time.

Further, it is noted that all of the light sources for exciting the photocatalyst described in these documents use ultraviolet lamps. Although the ultraviolet lamp has an excellent effect of exciting titanium oxide, it has a problem in that equipment and power for separately irradiating the catalyst are required.

In consideration of various problems in using a photocatalyst as the deodorant as described above, the inventor of the present invention is excellent in adsorbing / removing various malodorous gases existing in a food storage container, We conducted various studies in search of a new deodorizing catalyst that can oxidize and decompose the adsorbed malodorous components and regenerate its function only by irradiating the fluorescent lamp at high temperature. As a result, it was found that a deodorizing device made by combining a condensing lens with an adsorbent supporting titanium oxide (IV) is suitable for this purpose.

[0012] Among the light rays that are focused and irradiated with the light rays of the fluorescent lamp by the condensing lens, the near-ultraviolet rays are efficiently irradiated to the titanium oxide, so that the photocatalytic ability of the titanium oxide is sufficiently exerted. I found it. Furthermore, it was found that the adsorbed malodorous component is completely oxidized and decomposed by the photocatalytic action and released to the outside of the system, so that the deodorizing function is regenerated. Furthermore, as a result of examining the crystal structure of titanium oxide and the adsorbent to be used, the present invention has been achieved.

That is, the deodorizing device is composed of a condenser lens and a porous material supporting titanium (IV) oxide, and if necessary, an air circulation fan, so that the light flux of the condenser lens hits the porous material. It is a deodorizing device inside the container of a self-regenerating type food storage device that uses photocatalytic properties and is installed in the. Further, the titanium oxide (IV) is preferably one having an anatase type crystal system, and the condensing lens is preferably a molded body made of translucent plastic. Furthermore, a structure in which this porous material is placed within the focal length of the condenser lens is preferable.

Further, the deodorizing device is composed of a sheet and / or net containing a porous material supporting titanium oxide (IV) and a germicidal fluorescent lamp, and the germicidal lamp is mounted along a corner corner inside the storage. The present invention also includes an in-vessel deodorizing device of a self-regenerating type food storage device in which the sheet and the net are attached to the inner wall adjacent to the inner wall and, if necessary, the inner side of the germicidal lamp.

The present invention will be described in detail below.

The in-vessel deodorizing device of the self-regenerating type food storage device using the photocatalyst of the present invention comprises a condensing lens combined with an adsorbent made of a porous material carrying titanium oxide (IV). It is a deodorizing device inside a self-renewable food storage container.

Titanium oxide is a photocatalyst that exhibits a very highly active oxidizing power when irradiated with near-ultraviolet rays of 300 to 400 nm. This catalyst has the ability to oxidize and decompose almost all of the malodorous gas existing in the living space. Any titanium (IV) oxide having anatase-type or rutile-type crystal system can be used, but anatase-type having high photooxidation ability is more preferable.

As the adsorbent made of a porous substance, any substance having a large specific surface area and a high physical adsorption property due to Van der Waals force can be widely used. Examples thereof include activated carbon, silica, activated alumina, zeolite and the like. Further, as can be seen from the fact that these adsorbents have a large specific surface area, not only the surface that can be observed from the outside, but also the inside of the substance is filled with micropores, mesopores or cracks.

The activated carbon used in the present invention generally has a large specific surface area of several 100 m ² or more per 1 g, and can be widely used as long as it is a carbon material having high adsorptivity. As a raw material for the activated carbon, a charcoal such as a palm shell or wood is usually used, or coal is used. Further, the activation method may be obtained by any method such as activation by steam or carbon dioxide gas at a high temperature, or treatment with a chemical such as zinc chloride, phosphoric acid or concentrated sulfuric acid.

The shape of the activated carbon can be any of crushed charcoal, granulated charcoal, and granulated charcoal, and it is possible to use the charcoal processed into various shapes as described later.

The silica used in the present invention is an adsorbent produced by solidifying a silicic acid colloidal solution. The main component is silicon dioxide, which has a pore structure, has a specific surface area of 90 to 500 m ² / g, and exhibits high adsorption. The pore volume is not particularly limited, but it is preferably 0.3 ml / g or more in order to have sufficient adsorption performance.

The activated alumina used in the present invention is mainly composed of aluminum oxide, has a porous structure, and exhibits high adsorptivity. The pore volume is not particularly limited, but is preferably 0.3 ml / g or more in order to have a sufficient adsorptivity.

The zeolite used in the present invention is a crystalline aluminosilicate, which is a substance having a three-dimensional skeleton and a pore structure formed in the voids. It has a large specific surface area of more than 500 m ² / g and high adsorptivity based on it. The composition and structure are not particularly limited, and both natural products and synthetic products can be used. The pore volume is not particularly limited, but it is preferably 0.3 ml / g or more in order to have sufficient adsorption performance.

The adsorbent can be used in the form of particles or powder as it is, but it can also be used after being processed into various shapes such as a plate shape and a sheet shape with a binder as described later. For example, it can be used by being attached to a net by coating. Known methods can be used for these molding methods. Further, as these adsorbents, general commercial products can be used.

The condensing lens is preferably a molded body made of translucent plastic. Translucent plastics are preferable because they have high light transmittance and high near-ultraviolet light transmittance, and thus enhance the activity of the photocatalyst containing titanium (IV) oxide. Examples of the translucent plastics that can be used include polymethylmethacrylate and polycarbonate. Glass lenses have high visible light transmittance but low ultraviolet light transmittance.

Further, the shape of the lens may be a fisheye lens, or it is possible to use not only one lens but also a plurality of lenses having different optical axes, or a substrate having the same plane or a curved surface. A compound eye lens in which a large number of small lenses are closely arranged may be used. The fish-eye lens is the most preferable because it has a characteristic that it can effectively use almost all the light rays irradiated on the lens surface. Also, when using multiple lenses with different optical axes, it is effective even when the direction of the sun's rays changes, and when using a compound eye lens, the focal length becomes shorter, so The interval can be narrowed and the deodorizing device can be made more compact. In the present invention, since the objective is achieved if the component of the light beam that has passed through the lens hits any part of the porous material carrying the photocatalyst, it is not necessary to correct various aberrations of the lens, and the near-ultraviolet light does not need to be corrected. Any shape may be used as long as it has high visible light transmittance and excellent light condensing property.

Further, in the present deodorizing device, the porous material carrying the photocatalyst does not necessarily have to be installed at the focal point of the condenser lens, but rather is preferably installed at a position closer than the focal length. When this porous material is placed at the focal point of the lens, if the lens is exposed to the sun's rays, the light will concentrate at the focal point and only a small part of it will become extremely hot, making the porous material flammable such as activated carbon. In the case of a substance, there is a risk of burning, and the titanium (IV) oxide carried on it may undergo a chemical change and become deactivated. If the molded body is installed at a position closer than the focal length of the lens, if the sun's rays irradiate a certain area of the porous material, the malodorous components adsorbed on the porous material will be uniform. Suitable for oxidation and decomposition.

The photocatalyst of the present invention can be used by further adding a platinum compound having an oxidation catalytic property or an oxide such as nickel or iron.

[0029]

[Embodiment of device]

 The shape of the deodorant used in the in-vessel deodorizing device of the self-regenerating type food storage device of the present invention can be used in a state in which particles or powders are applied to the net as described above, but it is mainly a binder or an adhesive. In many cases, it is used in the form of a net formed by molding into a plate or sheet.

The adsorbent contained in the photocatalyst of the present invention has the function of adsorbing malodorous gas into its pores, but when the adsorption amount reaches saturation, it cannot adsorb further malodorous gas. In order to further increase the amount of malodorous gas adsorbed, it is necessary to support titanium oxide, which has a function of decomposing adsorbed malodorous components and regenerating the malodorous gas adsorbing function, near the pore inlet of the adsorbent and on the outer surface.

When a portion containing titanium oxide is irradiated with a light beam including near-ultraviolet rays, the malodorous component adsorbed to the portion is oxidized and decomposed by the photocatalytic action of titanium oxide, and an odorless and harmless gas is obtained. Next, it is released outside the system. The malodorous components adsorbed in the pores inside the adsorbent move to the adsorbent surface sequentially due to the diffusion phenomenon, and are contacted with titanium oxide to be decomposed. Through such a cycle, the adsorbent can be repeatedly adsorbed and regenerated to constantly maintain a high adsorption capacity, and a deodorizing catalyst having a long life can be obtained.

As a light source of near-ultraviolet rays, an ultraviolet lamp or a high-pressure mercury lamp can be used, but since these lamps are expensive and require electric power, they can be used at the place where the photocatalyst of the present invention is installed. It is desirable to use near-ultraviolet rays that are partially contained in the light such as. In particular, the light of a germicidal fluorescent lamp contains near-ultraviolet rays and other ultraviolet rays at a high rate, and therefore, it is more preferable that it can also be used for sterilization in a food storage container because it promotes the function of a deodorizing catalyst. Furthermore, when a germicidal lamp is attached to the vertical corners of the vessel, the heat of the germicidal lamp causes an updraft, which has the advantage that gas circulation occurs in the vessel and deodorant can be made to every corner of the vessel.

In addition, since the photocatalyst of the present invention contains titanium oxide and an adsorbent, the adsorbent acts to adsorb and remove malodorous gas even when the amount of light is not sufficient at night or during extinction. You can The absorbed malodorous gas is oxidatively decomposed by the light of the fluorescent lamp when it is turned on.

When operating the deodorizing apparatus of the present invention, a fan may be attached and used, if necessary, in order to improve the air circulation in the vessel and enhance the adsorption efficiency of the malodorous gas.

The photocatalyst of the present invention has a function of removing a trace amount of malodorous gas existing in the living space. A trace amount of amines, ammonia, mercaptans, etc. It absorbs malodorous gases such as aldehydes and lower carboxylic acids by the action of an adsorbent, and then irradiates a ray of light to oxidize and decompose the adsorbed malodorous components into odorless components. By releasing the decomposed components, the function of the photocatalyst to remove the malodorous gas is regenerated and the photocatalyst can be used semipermanently. This is the greatest feature of the deodorizing device of the present invention.

[0036]

【Example】

 Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 Activated carbon having a particle size of 32 to 60 mesh (trade name “Kuraray Coal GG”, manufactured by Kuraray Chemical Co., Ltd.) obtained from coconut shell as a raw material was used as an adsorbent. 30 ml of titanium tetraisoprocoxide was gradually added dropwise to 90 ml of a 1 mol aqueous nitric acid solution at room temperature with stirring, and stirring was continued for 3 hours to prepare a transparent titanium oxide sol. Further, 600 ml of distilled water was added, and a 1 molar aqueous sodium hydroxide solution was added to adjust the pH to 3. Thus, a colloidal solution of titanium oxide was prepared.

100 g of coconut shell activated carbon was added to this colloidal solution and stirred for 1 hour. The titanium oxide-supporting activated carbon was washed with distilled water until the pH of the washing liquid became 6 or more. This was vacuum dried at room temperature and then calcined at 300 ° C. for 1 hour to prepare titanium oxide (IV) -supporting activated carbon. Incidentally, it was confirmed by XRD (X-ray diffraction) measurement that titanium oxide obtained by hydrolyzing titanium tetraisoprocoxide under the same conditions without adding activated carbon had an anatase type crystal system.

100 g of the titanium oxide-supporting coconut shell activated carbon thus prepared and 20 g of a polyethylene powder binder were uniformly mixed, and then a molding frame made of silicone rubber was filled with the powdered mixture. The molding frame is 100 mm square and 10 mm thick, and is provided with a large number of protrusions for making a large number of square holes in order to make the molded body a lattice shape. This was heated to 130 ° C. and then cooled under pressure to obtain a lattice-shaped plate-shaped molded body as shown in FIG.

After storing food such as cake in a showcase and setting it at 5 ° C. and confirming by sensory test that odor is generated from the food, a deodorizing device made of the above-mentioned molded body is shown in FIG. installed. A condenser lens made of polymethylmethacrylate was set on top of the molded body. A fish-eye lens was used as the condenser lens, and the distance between the molded body and the lens was set to a position shorter than the focal length of the molded body so that the light beam of the fluorescent lamp could be efficiently irradiated onto the molded body. After 5 minutes of operation, the odor was reduced to a level at which almost no food odor was felt in the sensory test.

Further, the fluorescent lamp was repeatedly turned on and off at intervals of 12 hours and this test was continued for one month, but no food odor was continuously detected.

Example 2 100 g of titanium oxide-supporting coconut shell activated carbon prepared in the same manner as in Example 1 and 20 g of polypropylene powder binder were uniformly mixed, and then a powdery mixture was added to a molding frame made of silicone rubber. Was filled. The molding frame is 100 mm square and 10 mm thick, and a large number of cylindrical protrusions are provided on the mold frame so that a large number of circular holes can be made in the molded body. After molding, the same process as in Example 1 was carried out to obtain a plate-shaped molded product as shown in FIG.

The same apparatus as in Example 1 was set in the food storage, and croquettes and the like were stored in the storage and set at 60 ° C. As a result of performing the same deodorization test as in Example 1, the food odor was reduced to an undetectable level after 10 minutes.

Example 3 In the preparation of activated carbon supporting titanium oxide of Example 1, titanium oxide was supported by using fine particles of zeolite instead of activated carbon, and then polyethylene powder was added as a binder to obtain a sheet. It was molded into a shape. Similarly, Zeolite supporting titanium oxide was molded into a net-shaped sheet.

A sterilizing fluorescent lamp was attached along the vertical corner inside the freezer-refrigerator, and the deodorizing catalyst sheet obtained above was attached to the inner wall of the refrigerator adjacent to it. The germicidal fluorescent lamp was set to automatically turn on every 12 hours for 1 hour. Fig. 4 shows a perspective view of the part where the deodorizing device is installed.

When meat, fish meat and the like were stored for a long time in the freezer-refrigerator, the odor peculiar to the refrigerator was hardly felt.

Example 4 In Example 3, the net-shaped deodorizing sheet obtained above was further attached to the front surface of the indoor side of the germicidal fluorescent lamp in the form of a vertically divided cylinder into four equal parts. Fig. 5 shows a perspective view of the portion where the deodorizing device is installed.

A test similar to the above was conducted using this deodorizing device. As a result, the odor peculiar to the refrigerator was hardly felt.

[0049]

[Effect of device]

 The in-vessel deodorization device of the food storage device of the present invention irradiates the porous material carrying titanium oxide (IV) having photocatalytic properties with the light focused by the condensing lens, and the photocatalyst acts to put it inside the container. It has a function of decomposing and then decomposing a small amount of existing amines, ammonia, mercaptans, aldehydes and lower carboxylic acids, etc., and at the same time, the adsorption function is regenerated, so that it can be used semipermanently. This is the main feature of the deodorizing device inside the food storage device.

[Brief description of drawings]

FIG. 1 is a perspective view of a plate-shaped molded body prepared in Example 1, which is an embodiment of a deodorant used in the deodorizing apparatus of the present invention.

FIG. 2 is a vertical cross-sectional view of a food storage device when the deodorizing device of the present invention is installed inside the food storage device. In the figure, the internal structure of the storage other than the deodorizing device is omitted.

FIG. 3 is a perspective view of another embodiment of the deodorant used in the deodorizing apparatus of the present invention, which is a plate-shaped molded body prepared in Example 2.

FIG. 4 is a perspective view of an installation portion when the deodorizing apparatus of the present invention is installed inside a refrigerator-freezer.

FIG. 5 is a perspective view of an installation portion when the deodorizing apparatus of the present invention is installed inside a refrigerator-freezer.

[Explanation of symbols]

 1 Plate-shaped molded product having photocatalytic property 2 Vent hole 3 Deodorizing device 4 Condensing lens 5 Showcase 6 Fluorescent lamp 7 Refrigerator / refrigerator 8 Sheet-shaped molded product having photocatalytic property 9 Sterilizing fluorescent lamp 10 Net-shaped molded product having photocatalytic property

[Procedure amendment]

[Submission date] June 24, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

Claims (5)

[Scope of utility model registration request] 1. The deodorizing device comprises a condenser lens and titanium oxide.
Self-renewable food storage utilizing photocatalytic property, consisting of a porous substance supporting (IV) and, if necessary, an air circulation fan so that the light flux of the condenser lens hits the porous substance. In-vessel deodorizing device. 2. The in-container deodorizing device for a self-regenerating food storage device according to claim 1, wherein the titanium (IV) oxide has an anatase type crystal system. 3. The in-container deodorizing device for a self-recovering food storage device according to claim 1, wherein the condenser lens is made of translucent plastic. 4. The in-container deodorizing device for a self-recovering food storage device according to claim 1, 2 or 3, wherein the porous substance is installed at a position within a focal length of a fish-eye type condenser lens. 5. The deodorizing device comprises a sheet and / or net containing a titanium (IV) oxide-supporting porous material and a germicidal fluorescent lamp, the germicidal lamp being installed along the corner of the inside of the storage. An internal deodorizing device for a self-recoverable food storage device, in which the sheet and the net are attached to the inner wall adjacent to the inner wall and, if necessary, the inner side of the germicidal lamp.