JPH079223U - Food container - Google Patents

Abstract

(57) [Abstract] [Purpose] While maintaining the lightness and thermal conductivity of aluminum, there is no deformation due to the decrease in strength of the container body even after the high temperature treatment required for forming the fluorine resin layer, (EN) A food container in which the durability of a resin layer is improved and which has a high fungal growth suppression effect. [Constitution] 0.5 to 3% by weight of magnesium is contained,
An aluminum alloy having a content of an element as an impurity equal to or less than a specific amount, comprising an alloy plate having a thickness of more than 0.8 mm and not more than 1.35 mm, and having a thickness of 5 to 100 μm on at least one surface of the alloy plate. A food container that forms a fluororesin layer. Preferably, 1 to 50 parts by weight of a heat-resistant antibacterial agent which is a silver-based inorganic antibacterial agent or a copper-based inorganic antibacterial agent is dispersed in the fluororesin layer with respect to the fluororesin solid content.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a food container made of an aluminum alloy having a fluororesin layer formed on the inner surface thereof, and particularly for cooking and transporting cooked rice and the like for school lunch, cooking prepared foods and the like, and cooking for food used for transport, Regarding a container for transportation.

[0002]

[Prior art]

 At present, aluminum containers are often used as food containers for school lunches for food preparation and transportation because of their light weight and excellent thermal conductivity, and also for cooking rice and prepared foods. In order to prevent the food from sticking and to be easily removed when cleaning the container, a fluororesin layer having heat resistance, non-adhesiveness, water repellency, oil repellency, etc. is formed on the inner surface of the container.

[0003]

[Problems to be solved by the device]

 However, when the fluororesin layer is formed on the inner surface of the container, the fluororesin paint is applied to the aluminum container and then heated to about 400 ° C. to form the resin layer. The strength of the body is reduced and the container is likely to be deformed due to repeated use. When the container is deformed, there is a problem in that stacking cannot be performed during transportation and storage, workability deteriorates, heating unevenness easily occurs during cooking, and durability of the fluororesin layer deteriorates. As with the container itself, the carrying handle part made of the same material as the container that is caulked on the side of the container is also subject to a decrease in strength due to heating, which makes it easier to come off. There are some dangerous cases where the handle comes off during transportation, and it was strongly desired to develop a container with high safety and durability.

[0004] Furthermore, due to poor cleaning due to scratches, deformation, etc. of the food container, food residues adhere to the inside of the container, which easily causes the growth of fungi and odors that may cause food poisoning. There has been a demand for a food container capable of preventing these, that is, hygienic, highly safe, and durable.

That is, according to the present invention, while maintaining the light weight and heat conductivity of aluminum, the container body is deformed and the workability during transportation is reduced even after the high temperature treatment required for forming the fluororesin layer is performed. There is no problem of the handle falling off, uneven heating during cooking, etc., the durability of the fluororesin layer can be improved and cleaning is easy, and the effect of suppressing the growth of fungi is high, which is excellent in food hygiene. The purpose is to provide food containers.

[0006]

[Means for Solving the Problems]

 The food container according to claim 1 of the present invention contains 0.5 to 3% by weight of magnesium, and the content of elements as impurities is 0.25% by weight or less of silicon and 0.40% by weight or less of iron. , An aluminum alloy having a chromium content of 0.35% by weight or less and copper, manganese, and zinc contents of 0.10% by weight or less, each having a thickness of more than 0.8 mm and less than 1.35 mm. It is characterized in that a fluororesin layer having a thickness of 5 to 100 μm is formed on the inner surface of the plate.

A food container according to a second aspect of the present invention is characterized in that 1 to 50 parts by weight of a heat resistant antibacterial agent is dispersed in the fluororesin layer in the fluororesin layer.

The present invention is a heat-resistant material that maintains the lightness and heat conductivity that are characteristic of aluminum, and does not cause a decrease in strength even after heat treatment at about 400 ° C. for forming a fluororesin layer. Since a fluorine-based resin layer was formed on a water-resistant aluminum container to make it a food container, the container body is deformed, the work during transportation is reduced, the handle is dropped, uneven heating during cooking, and the durability of the fluorine-based resin layer is reduced. In addition to solving various problems such as heat resistance, by adding a heat resistant antibacterial agent to the fluorocarbon resin layer to form the food container, the container is provided with antibacterial properties with excellent safety and durability, and the container is washed. Propagation of microorganisms and generation of odor can be prevented afterward and during storage, and hygiene of the inner surface of the container can be further improved.

The aluminum alloy forming the fluorine-based resin layer contains 0.5 to 3% by weight of magnesium, and the content of elements as impurities is 0.25% by weight or less of silicon and 0.40% by weight or less of iron. The effect can be obtained by using chromium in an amount of 0.35% by weight or less and copper, manganese, or zinc in an amount of 0.10% by weight or less, respectively.

The thickness of the fluororesin layer has heat resistance, non-adhesiveness, water repellency, oil repellency, etc. due to the fluororesin's ability to prevent food sticking and easy removal of stains during cleaning. The thickness is optional as long as it is continuous, but from the viewpoint of durability and thermal conductivity of the resin layer, the thickness is preferably 5 to 100 μm, more preferably 10 to 80 μm. If the thickness is 5 μm or less, the resin layer may be peeled off due to corrosion after several uses, and if the thickness is 100 μm or more, the thermal conductivity may be reduced and heating unevenness of food may occur, which is not preferable.

Generally, the film strength of the fluorine-based resin layer is not high, and the value of the resin layer for food cooking applications is about B to HB according to the pencil scratch hardness test specified in JIS K5400. To compensate for this drawback, when forming a fluorine-based resin layer for food cooking such as frying pans and hot plates, it is usually necessary to spray ceramics, metals, etc., and provide a hard coating base layer to improve the resin layer strength. The present invention also applies this principle.

Fluorine-based resins that can be used in the present invention include polyvinyl fluoride (PVF), polyvinylidene fluoride (PVdF), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), and tetrafluoride. Ethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene-perfluoro Although there are alkyl vinyl ether copolymers (PFA) and the like, PTFE, FEP, PFA and the like are preferable in terms of non-adhesiveness and heat resistance, and they may be used alone or as a composite composition in which they are mixed. In addition, these fluorocarbon resins, acrylic resins, silicone rubbers, fluororubbers, epoxy resins, polyimide resins, polyamideimide resins, urethane resins, polyphenylene sulfide resins, polyparabanic acid amide resins, or a mixture thereof may be used. A resin other than a fluororesin such as a polyetherimide resin, a polyether sulfone resin, or a parahydroxybenzoic acid resin may be mixed as a binder, or an appropriate amount of an elastomer may be mixed. These fluorine-based resin components can be used in the form of liquid paint by dispersing them in a film form, a powder form, an aqueous system, or an organic solvent-based dispersion medium.

As the heat-resistant antibacterial agent, a known antibacterial, bactericidal, antifungal substance (a substance having a bacteriostatic action) having heat resistance, that is, a fluororesin layer is formed. If the effect is not impaired by the temperature and the antibacterial effect does not significantly decrease with time, any of them can be used. Examples thereof include metals such as silver, copper, zinc and tin, and organic or inorganic compounds containing them. In consideration of safety and sustainability of effects, silver-based inorganic antibacterial agents and copper-based antibacterial agents are used. Inorganic antibacterial agents are preferred.

As the silver-based inorganic antibacterial agent, for example, one in which silver is supported on ceramics to be in the form of fine particles is preferable in terms of durability and discoloration resistance. Examples of ceramics that can be used in the silver-based inorganic antibacterial agent include porous fine powders containing alumina, calcined white porcelain, titanium oxide, silica and ferrous oxide as main components and having an average particle size of 5 μm or less, preferably 1 μm or less. To be

The content of the heat-resistant antibacterial agent is arbitrary as long as the effect of the heat-resistant antibacterial agent is exhibited, but for example, as fine powder, 1 to 50 times the solid content of the fluororesin is added. It is preferable to use the fluororesin layer dispersed in an amount of 0.5% by weight, more preferably 3 to 30% by weight. If it is 1% by weight or less, the antibacterial property is insufficient, and if it is added in an amount of 50% by weight or more, the coating strength of the fluororesin layer is lowered, which is not preferable.

Any of a stirring mixing method, a tumbler mixing method, a shaking mixing method, a ball mill mixing method and a roller mill mixing method may be used for mixing the heat resistant antibacterial agent and the fluororesin.

As a method of forming the fluorine-based resin layer on the heat-resistant aluminum container, film lamination and coating are mainly mentioned. Laminate of fluororesin film may be formed into a container shape by pressing after laminating on an aluminum alloy flat plate. Alternatively, the film may be formed by pressing an aluminum alloy flat plate into a container shape by pressing. You may line it. As a coating method, when used in the form of a liquid paint in which a fluororesin is dispersed in an aqueous or organic solvent-based dispersion medium, dipping, air spraying, electrostatic spraying, spatula coating, roller coating, curtain coating, Centrifugal spin coating and electrophoretic coating are available. When used in the form of powder coating, powder spray, electrostatic spray, fluidized immersion, electrostatic fluidized immersion, probe back, and pressure molding are available.

Further, before forming the fluororesin layer, the following treatment may be performed in order to improve the adhesiveness to the heat resistant aluminum. That is, after soaking with solvent, acid, alkali, detergent, shower, bubbling, ultrasonic cleaning, and other general cleaning, sand blasting, shot blasting, grit blasting, honing, paper scrubbing, hairline treatment, metal or Ceramic spraying, alumite treatment, boehmite treatment, cracking treatment, chemical etching, and chemical conversion coating treatment are added.

Further, the solvent, dispersant and binder component to be used are finally determined from the dispersibility, coatability and film forming ability.

When the heat-resistant antibacterial agent is added to the fluororesin layer, it is preferable that the heat-resistant antibacterial agent is unevenly distributed on the surface of the fluororesin layer from the viewpoint of antibacterial effect per addition amount. In a two-layer coating in which a fluororesin-based coating film in which a binder is mixed in advance is coated on the article to be coated, and a fluororesin layer is further formed, it is possible to disperse and mix the heat-resistant antibacterial agent in the fluororesin on the surface. It is also preferable from the viewpoint of the strength of the coating film.

After coating as described above, if dried, the heat-resistant antibacterial agent and the solid content of the fluororesin remain, and a coating film is formed. Overcoating at this stage can achieve the required film thickness. The drying temperature depends on the type of solvent, but in the case of powder coating, baking can be performed immediately after coating. The baking temperature should be near the melting point of the fluororesin used. Then, after the baking treatment, it is allowed to cool and used as it is, or it is subjected to polishing, cutting, and press treatment so as to have predetermined dimensional accuracy and surface roughness.

The resin layer thus formed contains a heat resistant antibacterial agent, but does not reduce the inherent non-adhesiveness of the fluororesin. In addition, the fluororesin layer containing the heat-resistant antibacterial agent can be directly applied to form a coating film in the same manner as in the method for forming the fluororesin layer described above. It is also possible to form a system resin layer, and the same effect as described above can be obtained.

Regarding the heat-resistant antibacterial agent added to the fluororesin layer, the particle size and specific gravity of the particles are similar to those of the fluororesin paint (the specific gravity of the silver-based inorganic antibacterial agent carried on the ceramics is 2. 5 to 3.0, specific gravity of fluororesin particles of 2.1 to 2.2, average particle size of silver-based inorganic antibacterial agent particles of 5 μm or less, particle size of fluororesin particles, and 0.2 to 0.4 μm in liquid paint. Since the powder coating is 5 to 35 μm), both of them form a uniform distribution during the initial skin film formation before baking, and the fluororesin component migrates to the upper layer of the film during baking. It is considered that the final surface of the resin layer formed by the fluororesin is covered with the fluororesin due to its properties, the fact that the fluororesin has a slightly lower specific gravity than the inorganic antibacterial agent and has thermal fluidity. It contains no heat-resistant antibacterial agent It is considered to have the same effect as that of the aluminum alloy food container having the fluororesin layer formed thereon.

[0024]

【Example】

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

Example 1 (1) Material Substrate: aluminum specified in JIS H4000 5052 H34 (magnesium content is 2.2 to 2.8% by weight, other element content is 0.25% by weight of silicon) % Or less, iron 0.40% by weight or less, chromium 0.35% by weight or less, copper, manganese, and zinc each 0.10% by weight or less. Thickness: 1.1 mm) made container Undercoat: polytetrafluoro Lower layer film mainly composed of ethylene resin and polyether sulfone (Adron coating for undercoat manufactured by Tokyo Silicone) Topcoat: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer copolymer powder coating (Mitsui-Dupont Fluorochemical Co., Ltd.) Product name MP-10) (2) Manufacturing method FIG. 1 is a sectional view showing a food container of the present invention.

The base aluminum container is obtained by forming the aluminum alloy plate 2 into a container shape and attaching the handle 3 to the container body by the caulking portion 4. The base aluminum container thus manufactured. Was roughened by sandblasting with an alumina-based blasting material, and the undercoat was spray-painted. This is dried at 80 ° C. for 15 minutes (undercoat film thickness 8 to 12 μm), a top coat is electrostatically powder coated on the upper surface thereof, and then baked at 380 ° C. for 30 minutes to form a fluororesin layer 5 on the inner surface. A sample of the food container 1 of Example 1 was obtained (total film thickness 25 to 40 μm).

For comparison, an aluminum base material made of aluminum (not containing magnesium) specified in JIS H4000 1100-0 and subjected to the same molding and coating steps as in Example 1 was used as Comparative Example 1. did.

For Example 1 and Comparative Example 1, the mechanical strength of the aluminum base material, the strength of the container handle, and the pencil scratch hardness of the resin layer were evaluated by the following methods.

Mechanical strength of aluminum base material: Tensile strength, proof stress, elongation and hardness were measured by a common test method for metal materials specified in JIS Z.

Handle strength: As one cycle, 10 kg of water was put into a container, and the handle was held for 5 minutes, and this was repeated 50 cycles.

Pencil scratch hardness: Measurement was carried out by a pencil scratch test specified in JIS K 5400.

Table 1 shows the evaluation results.

[0033]

[Table 1]

As is clear from Table 1, the food container according to the present invention is improved in mechanical strength of the aluminum base material and further in hardness of the fluororesin layer, even though it is baked at a high temperature. was gotten.

Example 2 Samples having a total film thickness of 5 μm and 100 μm prepared by the same manufacturing method as the sample of Example 1 are referred to as Example 2- (1) and Example 2- (2), respectively. Those having film thicknesses of 3 μm and 110 μm were designated as Comparative Example 2- (1) and Comparative Example 2- (2), respectively.

The durability and the thermal conductivity of the resin layer of each sample are as follows. The durability of the resin layer is determined by heating the container surface to 100 ° C. and rubbing it with a plastic spatula 50 times. It was evaluated by cooking 10 kg of cooked rice for 40 minutes and inspecting the cooked rice. The evaluation results are shown in Table 2.

[0037]

[Table 2]

As is clear from Table 2, the food container according to the present invention was excellent in the durability and heat conductivity of the resin layer, but in the comparative example in which the film thickness was outside the range of the present invention, No one could achieve these effects at the same time.

Example 3 The surface of an aluminum alloy plate (same as that used in Example 1; thickness: 1.1 mm) defined in JIS H4000 5052 H34 having a size of 4 cm × 4 cm was degreased with trichlene and alumina particles were formed. Activated by sandblasting with 5% by weight of the resin content of a commercially available one-coat PTFE coating (DuPont's product name 420-108), silver-loaded ceramic powder (average particle size 0.5 μm A commercially available primer-coated surface with a chemical composition (Novalon, manufactured by Kagaku Co., Ltd.) added and mixed was overcoated, dried at 100 ° C. for 10 minutes, baked at 380 ° C. for 15 minutes, and allowed to cool in the air. In 1), the PTFE coating was replaced with a commercially available two-layer coating product, and a coating in which PTFE and an adhesive were mixed in the undercoat layer (trade name: EK1 908 manufactured by Daikin Co., Ltd.) Y) was used, and 5% by weight of silver-loaded ceramic powder (Toa Gosei Kagaku Co., Ltd., Novalon) was added to the surface of the PTFE coating (Daikin Co., Ltd., trade name EK-46 12WS). A metal plate prepared in the same manner as in Example 3- (1) except mixing was used as Example 3- (2), and the fine ceramic powder carried in the same manner as in Example 3- (1) was added. Metal plates coated with unmixed coating films were prepared as Comparative Example 3- (1) and Comparative Example 3- (2), respectively. After inoculating these surfaces with the intestinal bacterial solution, the surfaces were wrapped and the viable cell count after storage at 27 ° C. for 3 hours was measured. The same operation was performed without using the sample as a control. The results are shown in Table 3.

[0040]

[Table 3]

As is clear from Table 3, the number of germs of the metal plate on which the fluororesin layer of the present invention is formed is generally a sanitary problem even though it is subjected to high temperature treatment when the fluororesin layer is formed. The antibacterial effect was reduced to 10 ² order, which is said to be absent.

[0042]

[Effect of device]

 The present invention provides a heat resistant aluminum container with a fluorine resin layer that does not lose its strength even after the high temperature treatment required for forming the fluorine resin layer while maintaining the light weight and thermal conductivity of aluminum. Since it is formed into a food container, it prevents deformation of the container body, deterioration of work during transportation, drop of handle, uneven heating during cooking, and improvement of durability of fluororesin layer and easy cleaning, Furthermore, it was highly effective in suppressing the reproduction of fungi, and showed excellent food hygiene.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a food container according to a first embodiment of the present invention.

[Explanation of symbols]

 1 Food container 2 Aluminum alloy plate 5 Fluorine resin layer

Claims (2)

[Scope of utility model registration request] 1. Containing 0.5 to 3% by weight of magnesium, the content of elements as impurities is 0.25% by weight or less of silicon, 0.40% by weight or less of iron, 0.35% by weight or less of chromium, 0.10% by weight of copper, manganese and zinc
It is characterized by comprising an aluminum alloy plate having a thickness of more than 0.8 mm and having a thickness of 1.35 mm or less, and forming a fluorine-based resin layer having a thickness of 5 to 100 μm on the inner surface of the alloy plate. Food container. 2. The food container according to claim 1, wherein 1 to 50 parts by weight of the heat-resistant antibacterial agent is dispersed in the fluororesin layer with respect to the fluororesin solid content.