WO2000034146A1

WO2000034146A1 - Food container utilizing titanium oxide particles and method for preparing the same

Info

Publication number: WO2000034146A1
Application number: PCT/JP1999/006878
Authority: WO
Inventors: Masahiro Ohmori; Takashi Ohkubo; Masayuki Sanbayashi
Original assignee: Showa Denko K.K.
Priority date: 1998-12-09
Filing date: 1999-12-08
Publication date: 2000-06-15

Abstract

A food container having titanium oxide particles on the surface thereof, which is less susceptible to staining and easy to clean, even when stained, with long-term durability. Extremely high transparency of titanium oxide film, which can not be expected from a resin coating, allows the appearance inherent to the material of a container to be kept as it is, for example, a metallic gloss and a feeling of cleanness of a container made of a metal such as stainless steel. In the case of a glass food container, titanium oxide film leads to the increase of strength of the container, which in turn leads to permitting the decrease of thickness of the container, resulting in lowering the weight thereof.

Description

Specification

TECHNICAL FIELD The present invention relates to a food container using titanium oxide particles and a method for producing the same.

The present invention relates to a food container using titanium oxide particles, and more particularly to a food container that is hardly soiled and can be easily washed even when soiled. Furthermore, when the food container is a glass container, the mechanical strength of the container can be improved, and a food container that can maintain these effects for a long period of time is provided. Here, food includes beverages such as beer.

This application is based on a patent application filed in Japan (Japanese Patent Application No. 10-350046 and Japanese Patent Application No. 11-2861114), and the content of the Japanese application Shall be incorporated as a part of this specification.

This application was filed in the United States application no. 60, 136, 231, (filing date: May 26, 1999) and in the U.S. Claim the benefit of the application based on the date, application number undecided). Background art

Depending on the application, glass containers may be used for food containers such as barrels and evening tanks that transport or store beverages such as beer, juice, milk, and milk, and liquid foods, and large tanks used in tank trucks. Plastic and metal containers are used. Among these, metal containers are widely used because of their excellent durability, and stainless steel containers are widely used because they are more resistant to rust. On the other hand, glass containers are useful because of their flexibility and low cost.

Food containers intended for transportation and storage are used repeatedly and are often used outdoors, so the outside of the container and the spout are less likely to become dirty, and even if they become dirty, What can be washed is desired. In addition, glass containers are weaker in strength than stainless steel containers, so they have a thicker structure and are heavier. Therefore, weight reduction is required.

In order to make food containers less susceptible to contamination, coat the surfaces of the containers with fluororesin. There is a surface treatment method such as a method of increasing a contact angle with water by performing a fluorine treatment such as pitting, that is, a method of improving water repellency.

However, in the case of surface treatment such as coating the surface of a food container with a fluororesin, the color of the coating agent used affects the color of the food container, so the surface of the food container that requires cleanliness is required. There is a problem that it is not preferable as a processing method. In addition, the coating was worn or peeled off during use, and there was a problem with long-term use.

Further, when the material of the food container is glass, if the thickness is reduced to reduce the weight of the container, there is a problem that the mechanical strength is reduced.

An object of the present invention is to provide a food container which is hardly soiled, can be easily washed even when soiled, and maintains such an effect for a long period of time. In particular, if the food container is made of glass, the objective is to maintain the mechanical strength even when the thickness of the glass is reduced. Disclosure of the invention

The food container of the present invention has titanium oxide particles present on the surface. Therefore, it is difficult to be soiled, and even when soiled, it can be easily washed.

Also, unlike the resin coating agent, the titanium oxide film is excellent in transparency, so that the original appearance of the container can be maintained. It can be a container with the. If the material of the food container is made of glass, its mechanical strength can also be improved, so that the glass thickness can be reduced, resulting in a lightweight bottle. is there. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The food container used in the present invention is not particularly limited as long as it is used for transporting and storing foods and beverages, such as bottles, barrels, and the like for transporting beverages such as beer, juice, milk, and liquid foods. Containers such as tanks, or large evening tanks used for tank trucks And the like. There is no particular limitation on the material of these containers as long as they are suitable for safe and sanitary conditions for transporting and storing foods and the like, and glass, plastic, metal, etc. are usually used. Preferably, metal or glass having excellent durability is used because the metal or glass is used repeatedly. As the metal, rust-resistant stainless steel is preferable.

Such food containers are often used outdoors, and especially because the spout has a complicated uneven shape, stainless steel beer barrels that are difficult to clean and are difficult to wash, soda-lime glass, borosilicate glass, etc. There is a glass bottle that can be made from lee.

The titanium oxide particles used in the present invention have a photocatalytic function capable of decomposing organic substances and the like using ultraviolet rays, and are used for decomposing organic substances such as food-derived stains, disinfecting, and preventing mold generation. It works. Furthermore, since titanium oxide particles have high hydrophilicity, it is possible to prevent adhesion of organic substances such as oil components derived from foods, inorganic dust, sand and mud. In addition, when titanium oxide particles are used in a glass container, the mechanical strength is improved, so that the thickness of the glass can be reduced, and as a result, the weight of the entire glass container can be reduced. .

The crystal structure of such titanium oxide particles is not limited, and is usually a tetragonal low-temperature ananode-type, a high-temperature rutile-type, or an orthorhombic-type blue oxidite-type oxidation. Titanium particles are used, and preferably titanium oxide particles containing blue kite type titanium oxide particles. The titanium oxide particles containing the brookite-type crystal may include brookite-type titanium oxide particles alone, or may include rutile-type or ananases-type titanium oxide particles. When rutile-type or anatase-type titanium oxide particles are contained, the ratio of brookite-type titanium oxide particles in the titanium oxide particles is not particularly limited, but is usually 1 to 100% by weight, preferably 10 to 100% by weight. It is 100% by weight, more preferably 50 to 100% by weight. This is because the brookite-type titanium oxide has better photocatalytic performance than the rutile-to-analyze-type titanium oxide. The method for producing titanium oxide particles containing brookite-type crystals includes a method for producing titanium oxide particles containing brookite-type crystals by heat-treating anatase-type titanium oxide particles, titanium tetrachloride, Titanium chloride, titanium alkoxide, titanium sulfate There is a liquid phase production method of obtaining a titanium oxide sol in which titanium oxide particles are dispersed by neutralizing or hydrolyzing a solution of a titanium compound such as titanium oxide. These methods are not particularly limited as long as they can produce titanium oxide particles containing brookite-type crystals, but the photocatalytic performance, easiness of handling, and formation of a titanium oxide thin film of the obtained substance From the viewpoint of transparency, adhesion, and film hardness, the method described in Examples of the present invention is preferable. That is, titanium tetrachloride is added to hot water at 75 to 100 ° C, and titanium tetrachloride is hydrolyzed at a temperature of 75 ° C or more and below the boiling point of the solution while controlling the chloride ion concentration. To obtain titanium oxide particles containing bullite-type crystals as a titanium oxide sol, or to add titanium tetrachloride to hot water of 75 to 10 Ots, to obtain either nitrate ions or phosphate ions. Titanium tetrachloride is hydrolyzed and oxidized in the presence of one or both at a temperature of 75 ° C or higher and lower than the boiling point of the solution while controlling the total concentration of chloride, nitrate and phosphate ions. A method for obtaining titanium oxide particles containing brookite type crystals as a titanium sol is preferable.

The size of the titanium oxide particles is not particularly limited, but usually has an average particle size of 0.05 to 0.00. This is because if it is larger than 0.1 zm, the photocatalytic activity is reduced, so that it is difficult to contaminate, and even if it is contaminated, it is difficult to obtain the effect of easily decomposing organic substances and washing it. Further, the transparency of the titanium oxide particles is reduced, and in a food container having such titanium oxide particles present on the surface, the color of the titanium oxide particles affects the color of the food container, which is not preferable. If it is less than 0.05 wm, it is difficult to handle titanium oxide particles in the manufacturing process. The specific surface area of the titanium oxide particles is usually 20 m ² or more.

The titanium oxide particles thus obtained can be present on the surface of the food container by applying a sol of the titanium oxide particles to the food container and then drying, heat-treating, or sintering the food container surface. There is a method of adhering, a method of mixing titanium oxide particles with a paint or the like, applying the mixture to a food container, followed by drying and heat treatment. The titanium oxide particles may be directly fixed to a food container with a binder or the like.

If the pH of the sol of titanium oxide particles is less than 1, it may corrode metal food containers such as stainless steel, so filtration filtration, electrodialysis, ion exchange, and electrolysis For example, it is preferable to control the pH to 1 or more.

The method of applying the sol of the titanium oxide particles to the food container is not particularly limited, but a spin coating method, a flow coating method, a dip coating method, a spray coating method, a vacuum coating method, a roller coating method, a brush coating method, and a dipping method Any known method such as the method may be used. When the titanium oxide sol is applied, the coating amount is usually 0.01 to L0 m, in terms of the thickness of the applied film.

When a sol of titanium oxide particles is applied to a food container and then adhered to the surface by drying, heat treatment, sintering, etc., a sintering aid or a binder or binder precursor is added to the titanium oxide sol. It is also possible. Further, a binder may be applied to a food container in advance, and a base treatment for forming an undercoat layer may be performed. Sintering aids and binders enhance the adhesive strength between the titanium oxide particles and the food container and improve the film hardness. The addition of such a sintering aid or the use of a binder makes it difficult for the titanium oxide particles to be peeled off from the food container.

The type of sintering aid or binder and binder precursor differs depending on the material of the food container used, but the sintering aid is not particularly limited as long as it is brenstead acid, and is, for example, phosphoric acid, hydrochloric acid, or acetic acid. Organic carboxylic acids and the like are used. As the binder, for example, metal oxides such as silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, calcium oxide, and magnesium oxide are used. As the binder precursor, an alkoxide having the metal is used. This is preferable because the film strength can be increased. Particularly preferably, phosphoric acid as a sintering aid, alkoxides of silicon such as tetramethoxysilane and tetraethoxysilane as binder precursors, alkoxides of titanium, acetates of titanium, and titanium oxides as binders Body. Alkoxides of silicon such as tetramethoxysilane and tetraethoxysilane are condensed to form polysiloxane and organopolysiloxane, and serve as a binder.

The surface of the titanium oxide particles is covered with oxygen or a hydroxyl group in the atmosphere, and the sintering aid or the titanium oxide or a precursor thereof, which forms a phosphoric acid or silanol bond, or a titanium oxide or a precursor thereof is used. Binder is used for food containers and acids Since it condenses with the surface of titanium oxide particles and bonds strongly, it exhibits excellent adhesive strength with a small amount. Even if the food container is made of metal, the adhesion to the binder is strong due to the presence of the metal oxide layer on the surface. When the container is made of stainless steel, sintering aid phosphoric acid is preferably used. When the material of the container is glass, an alkoxide of silicon such as tetramethoxysilane or tetraethoxysilane, which is a binder precursor, is preferably used.

The hardness of the titanium oxide thin film formed using such a sintering aid, binder, or binder precursor also affects the material of the container, but when phosphoric acid is used, the hardness of the lead brush is generally 4H or more. When silicon oxide, zirconium oxide, titanium oxide and their precursors are used, they generally have a pencil hardness of 6 H or more, have excellent film strength, and are difficult to peel.

These sintering aids and binders may be used alone or in combination of two or more. When these are mixed and used, the mixing ratio can be arbitrarily selected. When the sintering aid is added, the amount of the sintering additive is usually from 10 ppm to 100 ppm with respect to titanium oxide. If it is more than 100 ppm, the sintering temperature needs to be set high, and the sintering time is undesirably long. On the other hand, if it is less than lOppm, the sintering effect is small, which is not preferable. When the binder or the binder precursor is added, the amount thereof is usually 5 to 50% by weight with respect to titanium oxide when converted as oxide. If the content is more than 50% by weight, the proportion of titanium oxide particles buried in the binder becomes large, so that the photocatalytic activity of the coating film is reduced. If the content is less than 5% by weight, the effect of the binder cannot be obtained, so that it is preferable. Absent.

The method of adding the sintering aid or binder / binder precursor is not particularly limited.However, a method of adding these to the titanium oxide sol and then applying it to a food container, or a method of applying the titanium oxide sol by a spray coating method In addition, there is a method of applying a sintering aid or a binder, or a binder precursor from another spray.

When the sol of the titanium oxide particles is applied to a food container and then dried, an appropriate solvent may be added to increase the drying speed. Usually, when the titanium oxide sol is dispersed in water, an organic solvent such as ethyl alcohol is used.

Before applying the sol of titanium oxide particles to a food container, In order to prevent the food container from deteriorating, the surface of the food container may be covered with a solution containing silica, fluororesin or the like, and dried to form a protective film.

After the sol of the titanium oxide particles is applied in this manner, drying, heat treatment, and the like are performed to fix the titanium oxide particles on the surface of the food container. The atmosphere for drying and heat treatment is not particularly limited, and is performed in the air, in a vacuum, in an inert gas, or the like, but is usually performed in the air. The temperature varies depending on the material of the food container and the type of sintering aid, binder, and binder-precursor when used, but is usually 20 to 800 ° C. When using an agent, a binder, or a binder precursor, the temperature is 20 to 450 ° C. The drying and heat treatment time is usually 5 minutes to 24 hours, preferably 15 minutes to 12 hours.

For example, when the material of the food container is stainless steel or glass, it is treated at 100 to 450 ° C using phosphoric acid as a sintering aid, or silicon oxide or its binder is used as a binder or binder precursor. When the precursor is treated at 20 to 450 ° C using a precursor such as tetramethoxysilane or tetraethoxysilane, or an alkoxide, chelate, or acetate of titanium, the film hardness formed by the titanium oxide particles is reduced. It is preferable because it can be further improved. Also in this case, the heat treatment time is usually 5 minutes to 24 hours, preferably 15 minutes to 12 hours.

When sintering aids, binders, and binder precursors are used, titanium oxide particles can be fixed to the container surface at a low temperature of 20 to 450 ° C, so that the energy cost for heat treatment is kept low. be able to. Further, when the material of the food container is glass, the titanium oxide particles can be fixed to the surface of the container at a temperature lower than the softening temperature of the glass without heating the glass to the softening temperature and fusing the titanium oxide particles. Therefore, deformation of the glass can be prevented. The softening temperature of glass is usually above 500 ° C.

In the food container in which the titanium oxide particles thus obtained are present on the surface, the thickness of the thin film is usually 0.05 to 10 m, and more preferably 0.03 to 0. 5 m. If the thickness is less than 0.05 m, photocatalytic activity and hydrophilicity are not sufficient. If the thickness is more than 10 im, the photocatalytic reaction is performed only near the surface of the titanium oxide thin film, and the amount of titanium oxide not involved in the photocatalytic reaction increases, which is economically advantageous. However, the thin film is easily peeled from the food container. Further, the transparency of the titanium oxide thin film is lowered, which is not preferable.

The food container having the titanium oxide particles on the surface in this way can decompose the dirt attached by the photocatalytic function of the titanium oxide particles, kill the microorganisms in contact, and suppress the growth thereof. In addition, titanium oxide particles have excellent hydrophilicity and the contact angle with water is less than 20 degrees, so that the dirt adsorbed on the food container, for example, the dirt on the outside of the container when used outdoors or the spout It is difficult for dirt, etc. to adhere, and even if dirty, it can be easily washed. Moreover, the film formed by the titanium oxide particles has excellent transparency and does not affect the color of the food container. When the food container is a glass container, the mechanical strength of the titanium oxide thin film is also improved. Furthermore, the presence of titanium oxide particles on the surface using a binder and / or a sintering aid allows the titanium oxide particles to be strongly adhered to the food container surface, has excellent film hardness, and is difficult to peel off. The above effects will be sustained for a long time. In this case, since the temperature at which the titanium oxide particles are fixed to the surface of the food container is as low as 20 to 450 ° C, the energy cost for heat treatment can be kept low and the food container can be kept low. When the material is glass, deformation due to heat can be prevented.

Such food containers are used not only indoors but also outdoors.In particular, since the spout has a complicated uneven shape or a shape having a large and small complicated curvature, it is easily soiled. It is preferably applied to stainless steel beer barrels and glass beer bottles that are difficult to wash. The ingredients of the beer are 91-93% by weight of water, 3.3-3.9% by weight of ethanol, and 3.1 :! The amount of carbon dioxide is 0.42 to 0.55%, and the extract, which is a non-volatile organic substance, contains 75 to 80% by weight of carbohydrates composed of total sugars such as dextrin. Contains. Therefore, among the beer components, extracts are the main cause of soiling.

Such dirt due to organic substances such as dextrin is decomposed by the photocatalytic function of the titanium oxide particles containing brookite-type crystals and the like, so that the dirt is less likely to be soiled, and even if soiled, it can be easily washed. Example

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

Example 1

954 mL of distilled water was charged into a 1 L internal volume glass reactor equipped with a reflux condenser, and 9

Heated to 5 ° C. Next, the reaction vessel was stirred at about 200 rpm, and while maintaining the liquid temperature in the vessel at 95, 46 mL of an aqueous solution of titanium tetrachloride was dropped into the reaction vessel at a rate of about 2 mL Zmin. Thus, a solution having a titanium tetrachloride concentration of 0.25 mol ZL (2% by weight in terms of titanium oxide) was obtained. After the completion of the dropwise addition, the mixture was heated to near the boiling point (104 ° C.) and maintained at that temperature for 60 minutes to hydrolyze titanium tetrachloride. The resulting sol was cooled and concentrated, and the chlorine generated by the hydrolysis was removed by electrodialysis using an electrodialyzer G3 manufactured by Asahi Kasei Kogyo Co., Ltd. to obtain a pH of 4.0 (chlorine ion of about 400 ppm). A water-dispersed titanium oxide sol was obtained. When the particles in the sol were observed with a transmission electron microscope, the particle size was 0.01 to 0.03 m.

To examine the crystal structure of the titanium oxide particles contained in this sol,

The particles were dried in a vacuum dryer at 60 ° C., and the obtained titanium oxide particles were analyzed by X-ray diffraction. X-ray diffraction was performed with an X-ray diffractometer (RAD-B rotorflex) manufactured by Rigaku Denki Co., Ltd. Cu was used for the tube. As a result, a peak indicating the diffraction of the (121) plane of the blue kite type crystal was detected at 20 = 30.8 °. Rutile and anazygous forms were not detected.

In order to apply the water-dispersed titanium oxide sol containing brookite-type titanium oxide obtained as described above, tetramethoxysilane, which is a silicon-based adhesive, and ethyl alcohol for improving a drying rate are added as a binder precursor. Thus, paints having the compositions shown in Table 1 were prepared.

The resulting paint is applied to a stainless steel beer barrel (volume of 10 L) by the brush method, dried at 50 ° C for 1 hour in the air, and heat-treated at 200 ° C for 2 hours in the air. A beer barrel having a titanium oxide thin film of 4 zm on the surface was obtained.

1 L of beer was sprayed on the upper and side surfaces of the beer barrel obtained in this manner with a sprayer, left outdoors for 3 months, and the appearance of the beer barrel was visually evaluated. Dirt is particularly strong in the complex uneven shape of the spout, and this part is rated Valued. Thereafter, 10 L of shower water at a water temperature of 20 ° C. was poured into a beer keg, and the ease of cleaning dirt was visually evaluated. The results are shown in Table 2.

table 1

Table 2

Example number Easy to clean Easy to clean

Example 1 ◎ ◎

Example 2 ◎ ◎

Example 3 〇〇 '

Example 4

Example 5 ◎ ◎

Example 6 ◎ ◎

Comparative Example 1 X X

Comparative Example 2 XX The abbreviations in Table 2 indicate the following contents.

①Difficulty of dirt

◎ Almost clean

〇 Young dirty

X quite dirty

②Easy to clean

◎ Dirt quickly removes

汚れ Slightly hard to remove dirt

X Does not remove dirt

Example 2

Before dropping the aqueous solution of titanium tetrachloride, phosphoric acid P0 ₄ ³ - except for adding to the reaction vessel in so that such a 200 p pm as in the same manner as in Example 1 was solution hydrolyzed fraction of titanium tetrachloride. A water-dispersed titanium oxide sol was obtained in the same manner as in Example 1 except that the pH of the obtained sol was set to 1.9 (chlorine ion: about 600 ppm, phosphate ion: about 200 ppm). Further, when the particles in the sol were observed in the same manner as in Example 1, the particle size of the particles was 0.01 to 0.03 m.

The crystal structure of the titanium oxide particles contained in this sol was examined in the same manner as in Example 1. As a result, a peak showing diffraction on the (121) plane of the brookite type crystal and a peak showing diffraction on the (110) plane, which is the main rutile type peak, were detected. In addition, although the main peak of the anazygase type could not be determined because it overlapped with the main peak of the brookite type, a peak indicating diffraction of the (004) plane of the anazygous type crystal was detected. Therefore, the obtained sol was a mixture of brookite-type crystals, ananases-type crystals, and rutile-type crystals. The content of these crystals was calculated as follows.

Titanium oxide of brookite-type crystal, ananode-type crystal, and rutile-type crystal each have the X-ray diffraction peaks shown in Table 3 (excerpted from J CPDS card). There are many overlapping parts. In particular, the d values of the main peaks of the blue kite type and the analog type are 3.51 and 3.52, respectively, and the blue kite type has a peak at 3.47, respectively. Peaks are virtually bulky Become.

As described above, since the intensity ratio between the blue and yellow anacheid type main peaks cannot be determined, here the blue kite type (1 2 1) plane that does not overlap with the anazygous type peak is used. Using the peaks, the intensity ratio of the peak where the above three peaks overlap with each other (the peak intensity of the blue kite-type (12 1) plane) / (the peak intensity where the three peaks overlap) is calculated. The content of anatase-type titanium oxide was determined. In addition, for the rutile type, the main peak, which indicates the diffraction of the (1 10) plane, and the intensity ratio of the above three peaks (rutile type main peak intensity) Z (peak intensity of the three peaks) The content was determined.

As a result, (peak intensity of the brookite-type (121) plane) Z (peak intensity of three overlapping) = 0.38, (rutile-type main peak intensity) Z (peak intensity of three overlapping) = 0. 05, which means that it contains about 70% by weight of bull kite-type crystals, about 1.2% by weight of rutile-type crystals, and about 28.8% by weight of ana-yose-type crystals.

Ethyl alcohol for improving the drying rate was added to the water-dispersed titanium oxide sol containing the phosphoric acid-containing brookite-type titanium oxide obtained as described above to prepare a paint having the composition shown in Table 1.

Except for using the coating material thus obtained, a peel barrel having titanium oxide particles present on the surface was obtained in the same manner as in Example 1, and similarly evaluated. The results are shown in Table 2. Table 3

Brookite (29-1360) Anatase (21-1272) Rutile (21-1276) d-value crystal plane intensity ratio d-value crystal plane intensity ratio d-value crystal plane intensity ratio

3.51 120 100 3.52 101 100 3.25 1 10 100

2.90 12 1 90 1.89 200 35 1.69 221 60

3.47 1 1 1 80 2.38 004 20 2.49 101 50 Example 3

Water-dispersed titanium oxide sol composed of ananases type crystals not containing brookite type

(The specific surface area of about ^{2 7 0 m 2 Z g)} , ethyl alcohol for improving the tetramethoxysilane and the drying rate is a silicon-based adhesive as the binder precursor was added pressure, coating the composition shown in Table 1 Was prepared.

A beer barrel having titanium oxide particles on the surface was obtained in the same manner as in Example 1 except that the thus obtained coating material was used, and evaluated similarly. The results are shown in Table 2. Example 4

A water-dispersed titanium oxide sol (specific surface area: 50 m ² / g) consisting of rutile-type crystals that do not contain brookite-type crystals, tetra-methoxysilane, a silicon-based adhesive as a binder precursor, and ethyl for improving the drying rate A paint having the composition shown in Table 1 was prepared by adding alcohol.

A beer barrel having titanium oxide particles on the surface was obtained in the same manner as in Example 1 except that the thus obtained coating material was used, and evaluated similarly. The results are shown in Table 2. Example 5

A glass vial having titanium oxide particles on the surface was obtained in the same manner as in Example 1 except that a glass beer bottle (large bottle: 5355 ml) was used instead of the stainless steel beer barrel. evaluated. The results are shown in Table 2.

Further, a strength test was performed on the glass beer bottle. As a simple measurement method for strength measurement, a 5 cm x 5 cm x 1.2 mm glass plate of the same composition as the glass constituting the beer bottle was used as an alternative. The glass plate was placed on a smooth table, and a stainless steel ball having a diameter of 10 mm was freely dropped from above. At this time, the height at which the stainless steel balls were allowed to fall freely was gradually increased, and the height at which cracks (cracks) entered the glass plate was measured to determine the height at which breakage occurred. The results are shown in Table 4. The higher the height, the better the mechanical strength. The measurement was performed five times, and the highest value was shown. Table 4

Example 6

A glass vial having titanium oxide particles on the surface was obtained in the same manner as in Example 2 except that a glass beer bottle (large bottle: 53.5 ml) was used instead of the stainless steel beer barrel. evaluated. The results are shown in Table 2.

Further, a strength test was performed on this glass beer bottle in the same manner as in Example 5. The results are shown in Table 4. Comparative Example 1

An untreated stainless steel beer barrel (volume of 10 L) in which titanium oxide particles were not present on the surface was evaluated in the same manner as in Example 1. The results are shown in Table 2. Comparative Example 2

An untreated glass beer bottle (large bottle: 5355 ml) having no titanium oxide particles on the surface was evaluated in the same manner as in Example 1. The results are shown in Table 2. Further, a strength test was performed on this glass beer bottle in the same manner as in Example 5. The results are shown in Table 4.

As shown in Table 2, beer barrels and beer bottles having titanium oxide particles present on the surface were resistant to soiling and easy to clean even if soiled. In particular, a beer barrel in which titanium oxide particles containing a large amount of brookite-type crystals were present on the surface was more excellent in such an effect. In the case of bottles, the mechanical strength is also improved as shown in Table 4. Was. Industrial applicability

As described above, since the food container of the present invention has titanium oxide particles on the surface, it is difficult to be soiled, and even when soiled, it can be easily washed. Further, the above effects can be further improved by making the titanium oxide particles contain brookite type crystals. .

Also, unlike the resin coating agent, the titanium oxide film is excellent in transparency, so that the original appearance of the container can be maintained. It can be a container with the. If the material of the food container is made of glass, its mechanical strength can also be improved, so that the glass thickness can be reduced, resulting in a lightweight bottle. is there.

In addition, since a sintering aid or binder can be used to adhere the titanium oxide particles to the food container, the titanium oxide particles are less likely to be peeled off, and are less likely to become dirty over a long period of time. It can also be easily cleaned. Further, when a sintering aid or binder is used, the titanium oxide particles can be fixed to the surface of the food container without heat treatment at a high temperature of 500 ° C. or more.

Claims

The scope of the claims

1. Food containers with titanium oxide particles on the surface.

2. The food container according to claim 1, wherein the titanium oxide particles contain brookite-type crystals.

3. The food container according to claim 1, wherein the surface on which the titanium oxide particles are present is made of stainless steel.

4. The food container according to claim 1, wherein the surface on which the titanium oxide particles are present is made of glass.

5. The food container according to claim 1, wherein the titanium oxide particles are present on the surface using a binder and / or a sintering aid.

6. The food container according to claim 3, wherein the titanium oxide particles are present on the surface using a binder and / or a sintering aid.

7. The food container according to claim 4, wherein the titanium oxide particles are present on the surface using a binder and a sintering aid.

8. The method according to claim 1, wherein the titanium oxide particles are present on the surface using a binder and a sintering agent, and are fixed at 20 to 450 ° C. Kuchiya 25.

9. The food container according to claim 3, wherein the titanium oxide particles are present on the surface using a binder and / or a sintering aid, and are fixed at 20 to 450 ° C.

10. The food container according to claim 4, wherein the titanium oxide particles are present on the surface using a binder and Z or a sintering aid, and are fixed at 20 to 450 ° C.

1 1. A method for producing a food container, characterized in that titanium oxide particles are present on the surface using a binder and / or a sintering aid.

12. A method for producing a food container, wherein titanium oxide particles are present on a surface using a binder and / or a sintering aid, and then fixed at 20 to 450 ° C.