JP3288265B2 - Oxygen absorbent and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an oxygen absorbent and a method for using the same. More particularly, the present invention relates to food,
The present invention relates to an oxygen absorbent and a quality preservative for preventing deterioration of quality of various articles and commodities such as clothing, pharmaceuticals, leather products, wood products, and precision instruments due to mold, fungi, insects, oxidation, and the like , and a method of using the same.

[0002]

2. Description of the Related Art Antibacterial agents including bactericides such as cresol, insecticides such as naphthalene, and antibacterial and antifungal agents containing silver, copper, zinc, platinum, etc., as agents for preventing damage to products and products caused by molds, fungi and insects. Etc. have been used. However, all of them are harmful to the human body, causing a problem of causing allergies and the like, and cannot be used for foods. Recently, oxygen-containing oxygen scavengers have been widely used as food deterioration inhibitors, but have the disadvantages that they can alter the taste and color of foods and have little effect on sterilization. Recently, attention has been paid to antibacterial effects and decomposition of organic substances by active oxygen such as OH radicals based on electrons and holes generated when titanium dioxide is exposed to light (Taoda et al., “Water and Wastewater,” Vol. 38, N.
o. 4, 290-296 (1996); Taota, "Ceramics" Vol. 31No. 7, 587-589 (1
996); Taota, “Tokai Chemical Industry Association Bulletin” No. 19
6, 1-4 (1996)).

[0003]

DISCLOSURE OF THE INVENTION In view of the above points, the present invention is an economical oxygen absorber which is excellent in safety and excellent in antioxidant effect, antifungal effect, bactericidal effect and insect repellent effect, and furthermore, a quality preservative . And a method of using the same.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, have found that titanium dioxide, which is a safe and harmless substance recognized as a food additive, is incompatible with nitrogen gas or the like. When heated in an active gas or irradiated with light in a closed system, titanium dioxide with oxygen deficiency is obtained.If this is placed together with food or clothing in a closed system, the oxygen in the system can be reduced. It absorbs oxygen to create an oxygen-deficient state, prevents oxidation, and exhibits excellent bactericidal and antifungal action and insect repellent action.At that time, if the titanium dioxide having oxygen deficiency is exposed to light, electrons and positive The present inventors have found that pores are formed to decompose toxins produced by bacteria and molds by the redox action, that is, photocatalysis, and that the propagation of various bacteria and molds can be effectively prevented, thereby completing the present invention. That is, the present invention is an oxygen-absorbing agent containing a titanium dioxide having an oxygen deficiency as an active ingredient, and in one closed system together with the one that the oxygen absorbent subject to quality maintenance, light in the oxygen absorbent to methods of using the oxygen absorber, characterized in that held in hits.

[0005] It should be noted that in the literature of Taoda or Taoda et al., One of the present inventors mentioned in the section of "prior art", there is a description of the photocatalytic action that occurs when titanium dioxide is irradiated with light. There is no description or suggestion about titanium dioxide having a defect, nor is its oxygen absorbing ability or photocatalytic action described or suggested.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The oxygen-deficient titanium dioxide used in the present invention may be in a crystalline form such as rutile or brookite or in an amorphous form, but more preferably in an anatase form. The shape of titanium dioxide having oxygen vacancies is not particularly limited, and may be, for example, granular, spherical, plate-like, columnar, cylindrical, powdery, granular, or the like. Powders and granules having a large particle size are more preferable, and ultrafine particles are particularly preferable. Further, the purity of titanium dioxide having oxygen deficiency can be used even if it is low. However, it is preferable that the purity is high from the viewpoint of performance.
0% or close to it is preferably used.

[0007] The proportion of oxygen vacancies in the titanium dioxide having oxygen vacancies used in the present invention is in the range of 0.01% to 50% of the number of oxygen atoms in the titanium dioxide, that is, 0% in the titanium dioxide. Those from which 0.01 to 50% are eliminated are preferred. If the oxygen deficiency ratio is less than this, the oxygen absorption capacity becomes 1 ml or less per 1 mol of titanium dioxide, and the oxygen absorption capacity is too small to have a bactericidal and antifungal effect and an insect repellent effect. It is difficult to absorb the bacteria, and the bactericidal and antifungal action and the insect repellent action are reduced.

[0008] The oxygen-deficient titanium dioxide used in the present invention is produced by heating titanium dioxide in an oxygen-free atmosphere. The higher the heating temperature, the shorter the manufacturing time, the greater the percentage of oxygen defects, and the greater the oxygen absorption capacity.However, if the heating temperature is too high, the titanium dioxide crystal form becomes rutile with low photocatalytic activity. Therefore, the heating temperature is preferably up to 800 ° C. In addition, when producing titanium dioxide having oxygen defects by heating titanium dioxide, the production time can be shortened, the ratio of oxygen defects is increased, and the oxygen absorption capacity is increased if light irradiation is performed. As the light, natural light, ultraviolet light, visible light, or the like can be used, and light having a short wavelength such as ultraviolet light is preferable. Production under light irradiation can also be carried out at room temperature.

The atmosphere for producing titanium dioxide having oxygen defects may be an oxygen-free atmosphere, but may be an atmosphere of a rare gas element such as argon, neon, helium, nitrogen gas, hydrogen gas, or a mixed gas thereof. Preferably, there is. Titanium dioxide having oxygen defects can also be produced by irradiating titanium dioxide with light in a closed system, and can be produced promptly by heating at this time. Further, when titanium dioxide having oxygen vacancies is produced under reduced pressure, it can be produced quickly. The crystal form and shape of the titanium dioxide having oxygen vacancies manufactured as described above are basically the same as the crystal form and shape of the titanium dioxide used as a raw material, but when heated at a high temperature, Metastasis occurs.

The oxygen absorbent of the present invention may be composed of only the titanium dioxide having oxygen vacancies produced as described above, but may be composed of titanium dioxide having oxygen deficiencies supported on various carriers. Is also good. The carrier is not particularly limited, and examples thereof include silica gel, zeolite, clay, clay, glass beads, plastic, and paper.

The titanium dioxide having oxygen vacancies supported on the carrier can be produced by simply mixing the titanium dioxide having oxygen vacancies and the carrier. However, from the viewpoint of adhesion, production is carried out as follows. Is preferred. That is, a titania sol prepared by hydrolyzing a suspension of titanium dioxide powder or an alkoxide of titanium (such as titanium tetraisopropoxide) in the presence of a catalyst such as nitric acid is coated on a carrier, and calcined by heating and heating. Is converted to titanium dioxide, or after titanium dioxide is impregnated into the fibers of the carrier, from titanium dioxide, in the same manner as the method for producing titanium dioxide having oxygen deficiencies,
It can be produced by removing oxygen.
The method of producing titanium dioxide supported on a carrier as described above is described in, for example, Taoda et al., “Water and Wastewater,” Vol. 38, no. 4, 290-296 (19
96).

The oxygen thus obtained according to the present invention
Put the absorbent in an air-permeable bag and put it in a box, can, or, preferably, in a sealable container, along with food and clothing, pharmaceuticals, leather goods, wood products, precision machinery, and other goods and goods to be preserved. In addition to absorbing oxygen in the system and creating an oxygen-deficient state to prevent oxidation, it exhibits excellent antibacterial and antifungal action, insect repellent action, and does not allow harmful chemical substances to penetrate into goods and products, and it is safe Its quality can be maintained for a long time.

[0013] When the titanium dioxide is exposed to light by making the bag or the container transparent at the time of its use, electrons and holes are generated in the titanium dioxide and its oxidation-reduction action, that is, Oxygen in the system is converted into active oxygen by photocatalysis, and its strong oxidizing power causes odor and bacteria in the system.
In addition to decomposing mold toxins into carbon dioxide, it is possible to effectively prevent germs and mold from growing. In addition,
As the light, light containing a large amount of ultraviolet light is preferable, but natural light or visible light, or light from a light bulb or a fluorescent lamp may be used, and such light exerts a photocatalytic action.

The amount of the oxygen absorbent used in the present invention can be determined by comparing the amount of oxygen in the system using the oxygen absorbent with the oxygen absorbing ability of titanium dioxide having oxygen deficiency in the oxygen absorbent. When the oxygen absorber is used under light-free conditions, the amount of oxygen in the system is brought to the desired amount (this amount can vary depending on the individual case used and its purpose), for example zero. It is necessary to use an oxygen absorber in an amount corresponding to the above, but under light conditions, it is not always necessary to use this amount, and an amount smaller than this amount, for example, half or 1/10 of the amount May be used. The reason is, as already mentioned, the residual oxygen in the system is changed to active oxygen by photocatalysis, which effectively prevents the smell and toxins in the system from being decomposed into carbon dioxide and preventing the growth of microorganisms. This is because oxygen in the system is further reduced.

[0015]

Examples of the present invention will be described below. Example 1 10 g of ultra-fine titanium dioxide particles previously dried were placed in an electric furnace and heated at 800 ° C. in a nitrogen stream, and as a result, a 12% weight loss was observed. This corresponds to about 30% of the oxygen atoms in titanium dioxide being eliminated. The obtained oxygen-deficient titanium dioxide ( oxygen absorbent ) is placed in a paper bag through which air is passed, placed in a plastic container having a capacity of 500 ml containing Japanese confectionery and sealed, and oxygen in the air in the container is measured with an oxygen concentration meter. The concentration was measured. As a result, the oxygen concentration sharply decreased, and reached almost zero after several tens of minutes. And oxygen absorption
When no absorbent was added, mold grew after 3 days, but the mold with oxygen absorber did not grow even after half a month. When the same experiment was repeated using this oxygen absorbent, no change was observed in the effect.

Example 2 10 g of anatase-type granular titanium dioxide having a diameter of about 5 mm previously dried was placed in an electric furnace, heated at 150 ° C. under reduced pressure, and then allowed to cool to room temperature. As a result, a 1% weight loss was observed. This is about 2.5% of the oxygen atoms in titanium dioxide.
% Corresponds to desorption. The obtained oxygen-deficient titanium dioxide ( oxygen absorbent ) was placed in a container allowed to allow air to pass through, and placed inside a lid of a transparent glass container (volume 250 ml) containing peach juice, and the lid was closed. .
Then, as a result of measuring the oxygen concentration in the residual air in the upper portion of the container with an oximeter, the oxygen concentration was reduced to 8%. Then, when the container was moved to a bright place, the oxygen concentration further decreased to almost zero. And, if you did not put the oxygen-absorbing agent, but has also become strange taste comes with a color in peach juice in less than a day, that put the oxygen-absorbing agent even after three days of peach juice There was no change in color or taste. After the experiment, the oxygen absorber was taken out, and the crystal form was examined with an X-ray diffractometer.
00%.

Example 3 A volume of 100 g of 15 g of previously dried titanium dioxide powder was added.
Was sealed in a transparent plastic container, and irradiated with light from a xenon lamp of 300 W while reducing the pressure with a pump. As a result, a 3% weight reduction was observed. This corresponds to about 7.5% of the oxygen atoms in titanium dioxide being eliminated. Then, the cabbage pickle wrapped in wrap was put into the container, the container was sealed, left under a fluorescent lamp, and the oxygen concentration in the air in the container was measured with an oximeter. As a result, the oxygen concentration decreased to almost zero. And one week later, if no oxygen absorber was added, the Chinese cabbage pickles were sour,
Those containing the oxygen absorbent had no change in taste.

Example 4 120 g of titanium dioxide pellets having a diameter of about 1 cm, which were obtained by mixing equal amounts of anatase type titanium dioxide powder and clay and sintering the mixture.
Was placed in an electric furnace, heated from room temperature to 500 ° C. in an argon stream, and then allowed to cool to room temperature. As a result, a 5% weight loss was observed. This corresponds to about 25% of the oxygen atoms in titanium dioxide being eliminated. Obtained oxygen absorption
The absorbent was placed in an oxygen-permeable transparent plastic bag, placed on a raw tea buckwheat placed in a transparent plastics container having a volume of 2 L, sealed, placed under an electric light of 2000 lux, and placed in a container with an oximeter. The oxygen concentration in the inside was measured. As a result, the oxygen concentration decreased to zero. When no oxygen absorber was added, the green color of chlorophyll of buckwheat faded after 5 days. However, when oxygen absorber was added, the color did not change even after 20 days. Was.

Example 5 50 g of previously dried titanium dioxide powder was placed in a ceramic container, placed on a hot plate in a glove box, and the glove box was closed. It was irradiated with light from a 500 W mercury lamp and heated to 250 ° C. As a result, 14
% Weight loss was observed. This corresponds to about 35% of the oxygen atoms in titanium dioxide being eliminated. The obtained oxygen-deficient titanium dioxide ( oxygen absorbent ) is placed in a paper bag through which air passes, placed in a clear plastic container having a capacity of 500 ml containing a cold medicine, and hermetically sealed. Was used to measure the oxygen concentration in the air in the container. As a result, the oxygen concentration sharply decreased and became almost zero within several minutes. And, as a result of examining the quality of cold medicine after one month, if you did not put the oxygen-absorbing agent, but the oxidation of vitamin C in the cold medicine was going, if you put the oxygen absorber of vitamin C quality Did not change.

Example 6 Anatase spherical titanium dioxide having a diameter of about 7 mm was previously dried in a small chamber of a transparent plastic container (capacity: 300 ml) in which an object was placed inside the lid and a small chamber was provided so that air could pass through. After charging 20 g, the air inside was replaced with argon gas. Next, sunlight was applied to the titanium dioxide from the outside of the container for about one hour to desorb oxygen, thereby producing titanium dioxide ( oxygen absorbent ) having oxygen defects. Thereafter, apple juice was poured into the container, which was then sealed. The container was placed in a bright place, and the oxygen concentration in the residual air in the container was measured with an oximeter. As a result, the oxygen concentration sharply decreased to 5%, and then decreased gradually to almost zero.
And, if you did not put the oxygen-absorbing agent, it has been colored in apple juice in less than half a day, oxygen absorption
When the agent was added, the color did not change even after one day.
After the experiment, the titanium dioxide was taken out, and the crystal form was examined with an X-ray diffractometer, and as a result, it was 100% anatase.

Example 7 100 g of previously dried granular titanium dioxide having a diameter of about 5 mm was placed in an electric furnace and heated to 700 ° C. in a hydrogen stream.
A 20% weight loss was observed. This corresponds to about 50% of the oxygen atoms in titanium dioxide being eliminated. The obtained titanium dioxide having oxygen deficiency ( oxygen absorbent ) is scattered over brown rice in a transparent plastic container having a capacity of 4000 ml for up to 8 minutes and sealed, and then placed by the south side window, and measured with an oximeter. The oxygen concentration in the container was measured. As a result, the oxygen concentration rapidly decreased to zero. Oxygen absorption
When the agent was not added, the parasite was found after 10 days, but when the oxygen absorber was added, the insect was not seen even after one month, indicating an insect repellent effect on brown rice.

Example 8 30 g of anatase type titanium dioxide pellets having a diameter of 2 mm, which had been dried in advance, were placed in an electric furnace, heated at 150 ° C. in the air, and allowed to cool to room temperature. As a result, a 0.1% weight loss was observed. This corresponds to about 0.25% of the oxygen atoms in the titanium dioxide being eliminated. The obtained titanium dioxide having oxygen deficiency ( oxygen absorbent ) is placed in a Japanese paper bag, placed in a transparent plastic container having a capacity of 500 ml together with potato chips, placed in the sunshine, and the oxygen concentration in the container is measured with an oximeter. Was measured. As a result, the oxygen concentration gradually decreased to 0%. Two weeks later, it was opened and the peroxide value (POV) of the potato chips was checked. As a result, the potato chips increased from 4.5 to 42 (meq / kg) when no oxygen absorbent was added. When the oxygen absorbent was added, the retentivity was kept at 4.5 (meq / kg), and a remarkable effect of preventing oxidation was observed.

Example 9 90 g of a 3 mm diameter previously dried pellet of silica gel coated with titanium dioxide (titanium dioxide content: 1)
0%) was placed in an electric furnace, heated at 550 ° C. in a helium stream, and allowed to cool to room temperature. As a result, a 1.8% weight loss was observed. This corresponds to about 45% of the oxygen atoms in titanium dioxide being eliminated. Obtained oxygen absorption
The absorbent was put in a bread case with a capacity of 1200 ml together with the bread, sealed, placed in a bright place, and the oxygen concentration in the air in the container was measured with an oximeter. The oxygen concentration decreased to almost 0. . When no oxygen absorber was added, mold grew after 3 days, but when oxygen absorber was added, no mold grew even after 2 weeks.

Example 10 30 g of 4 mm pellets of pre-dried anatase-type titanium dioxide were placed in a ceramic container, placed on a microbalance in a glove box, and the gas atmosphere was replaced with argon. About 0.1 of oxygen atoms in
The glove box was irradiated with black light until oxygen equivalent to 01% was eliminated. The obtained titanium dioxide having oxygen deficiency ( oxygen absorbent ) is placed in an oxygen-permeable transparent plastic bag, placed in an oxygen-impermeable transparent plastic bag containing 100 g of butter peanuts, and then sealed. , Placed in the sun. As a result, when the oxygen absorber was not added, the peroxide value (POV) of butter peanut increased from 0 to 22 (meq / kg) one week later, but the oxygen absorber was added. In case, 2 (meq / kg)
And a remarkable effect of preventing oxidation was observed.

Example 11 5 g of anatase-shaped granular titanium dioxide having a diameter of about 3 mm previously dried was placed in an electric furnace and heated to 300 ° C. in a mixed gas stream of nitrogen and argon. As a result, a 5% weight loss was observed. . This is about 12.5% of the oxygen atoms in titanium dioxide
Corresponds to desorption. The obtained oxygen-deficient titanium dioxide (oxygen absorbent) was placed in a transparent plastic bag permeable to oxygen, and air was placed at the stopper of a 720 ml-volume bottle containing sake, which was lit at 65 ° C. for 10 minutes. It was placed in a flowable manner, sealed, and placed near a window. The oxygen concentration in the air in the container was measured with an oxygen concentration meter. As a result, after the oxygen concentration decreased to 3%, it gradually decreased to almost zero.
Became.

One month later, the degree of coloring of the sake contained therein (using a 430 mm 10 mm cell) and iron ion concentration were examined, and a sensory test was conducted. As a result, when no oxygen absorber was added, the iron ion concentration was unchanged at 0.044 ppm, but the degree of coloring increased from 0.002 to 0.0032, whereas when the oxygen absorber was added, Did not change the iron ion concentration and the coloring degree was almost unchanged at 0.0022. In addition, taste, smell, 5-point method by the eight panelists for the color (1: best) the results of the evaluation, the oxygen
When no absorbent was added, the value was 2.5,
When an oxygen absorbent was added, an excellent value of 1.2 was obtained. Further, a similar experiment was performed using an iron-based oxygen absorber instead of the above-mentioned oxygen absorbent .
The coloration increased from 044 ppm to 0.053 ppm, the coloring degree also increased from 0.002 to 0.0034, and the result of the sensory test was 2.7, indicating astringency and off-flavor. After the experiment, the titanium dioxide was taken out, and the crystal form was examined with an X-ray diffractometer. As a result, it was found to be 100% anatase. As mentioned above,
It has been found that the oxygen absorbent of the present invention has excellent performance as compared with the iron-based oxygen absorber .

[0027]

As described above, the oxygen absorber of the present invention is excellent in safety, and is excellent in antioxidant effect, antifungal effect, bactericidal effect and insect repellent effect. The oxygen absorbent of the present invention is made from titanium dioxide, which is a safe and harmless substance recognized as a food additive, and is produced by simply desorbing a part of the oxygen, so that the safety is high. It is presumed that.

The present oxygen absorbent is used in a closed system for foods and medicines,
When placed together with clothing, etc., it absorbs oxygen in the system to create an oxygen-deficient state, thereby preventing oxidation and exhibiting excellent fungicidal and fungicidal action and insect repellent action. At this time, if light is applied to the titanium dioxide, electrons and holes are generated on the titanium dioxide, and active oxygen is generated by the oxidation-reduction action, and the strong oxidizing power causes smell in the closed system. Fungus,
Organic substances such as toxins produced by molds are oxidized and decomposed to carbon dioxide to consume oxygen in the system, and active oxygen can effectively prevent the growth of various bacteria and fungi.

Titanium dioxide is also used in paints, cosmetics, toothpastes, etc., and has the advantages of excellent weather resistance and durability, and safety and harmlessness. Therefore, the oxygen according to the invention
The absorbent is also excellent in heat resistance, light resistance, weather resistance, stability and safety, can also adsorb and remove a certain amount of moisture, and is likely to be excellent in water resistance. Furthermore, the oxygen absorber according to the present invention can be easily regenerated by applying heat or light and can be used semipermanently repeatedly.
Very economical.

──────────────────────────────────────────────────続 き Continuing from the front page (73) Patent holder 597039869 Toru Nonami 3-9-6 Kibogaoka, Chikusa-ku, Nagoya-shi, Aichi Prefecture (73) Patent holder 597095980 Mitsuharu Fukaya 1-6 Kita-chikusa, Chikusa-ku, Nagoya-shi, Aichi Prefecture No. 32 Chikusa Nishi-House 2 Building 501 (74) The above five agents 100091856 Patent Attorney Shozo Sakaguchi (72) Inventor Hirofumi Taota 1-70 Heiwagaoka, Meito-ku, Nagoya City, Aichi Prefecture Inokoishi House 4 Building 301 (72) Inventor Eiji Watanabe 41-year-old Zenta Nitta character, Saya-cho, Kaifu-gun, Aichi Prefecture (72) Inventor Toru Nonami 1-70 Heiwagaoka, Meito-ku, Nagoya-shi, Aichi Prefecture Inokoishi House No. 302 ( 72) Inventor Mitsuharu Fukaya 1-6-2 Kita Chikusa, Chikusa-ku, Nagoya City, Aichi Prefecture Chikusa-Nishi Housing 2 Building 501 (72) Inventor Hiroshi Nakazawa 3-33-13 Honcho, Funabashi-shi, Chiba Maru Within Industrial Co., Ltd. (72) Inventor Hideaki Omori 3-33-13, Honcho, Funabashi-shi, Chiba Referee Chief Referee Kazushige Itabashi Referee, Yasuyuki Yamada Referee Yasuyuki Yamada Referee Osamu Satoh, 56 Document JP-A-7-316342 (JP, A) Journal of the Chemical Society of Japan 1986 No. 8. P 1084-1090 (58) Field surveyed (Int. Cl. ⁷ , DB name) A01N 59/16 B01J 35/02 C01G 23/047 A23L 3/358

Claims (4)

(57) [Claims] 1. An oxygen absorber containing titanium dioxide having oxygen vacancies as an active ingredient. 2. The oxygen absorbent according to claim 1, wherein the titanium dioxide having oxygen deficiency is in a crystalline form of anatase. 3. The oxygen absorbent according to claim 1, wherein the proportion of oxygen deficiency in titanium dioxide having oxygen deficiency is 0.01 to 50%. 4. The acid according to claim 1, wherein
In one closed system and containing absorbent with those of interest for maintaining quality, methods of using the oxygen-absorbing agent characterized by retaining in a state where the light impinges on the oxygen absorbing agent.