JPH078551B2 - Material with deoxidizing function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a material having a deoxidizing function, and an object of the invention is to remove oxygen existing in a closed container and to easily eat and drink the oxygen. It is an object of the present invention to provide a material having a deoxidizing function that prevents deterioration of raw materials and the like and enables long-term storage.

(Prior Art) Conventionally, some foods and drinks, chemicals, etc. cause decomposition, deterioration, and deterioration when they come into contact with oxygen in the air,
As a method for preventing this, for example, an oxygen scavenger (reducing organic compound such as sulfoxylate or nithionite) that absorbs oxygen together with the contents is placed in a closed container, or a breathable film is used. A method for absorbing and removing oxygen in the air in a closed container by packaging the product in a container is used.

(Problems to be Solved by the Invention) However, in the above-described method, a package made of a breathable container or a breathable film containing an oxygen scavenger must be sealed together with the contents, so that it is distinguished from the contents. However, it has the drawbacks that it is difficult to remove the heat generated by the rapid oxidation reaction and may adversely affect the contents. Is the reality. If the sealed container itself can be manufactured from a material having a deoxidizing function, there is no need to prepare a deoxidizing agent separately, the handling is simple, and deoxidation from the liquid substance is easy, which is very useful. Deoxidizing method.

(Means for Solving Problems) As a result of intensive research conducted by the present inventors to develop a material having a deoxidizing function capable of achieving the above object,
When a hydrophilic coating layer and an oxygen / water permeable coating layer formed of a specific synthetic resin film are provided on the metal surface, oxidation of the metal progresses extremely rapidly and the generated metal oxide can be transmitted to the outside. The present inventors have found that there is no such thing and have completed the present invention.

That is, the present invention is characterized in that an oxygen / water permeable coating layer formed of polymethylpentene or polybutadiene is provided on a hydrophilic coating layer provided on the surface of a metal material that reacts with oxygen. It relates to a material having a function.

The material having a deoxidizing function in the present invention, except for the hydrophilic coating layer and the oxygen / water permeable coating layer, may be a material composed entirely of metal, or a plastic film,
A material obtained by applying a metal thin film such as iron, zinc, manganese, etc., which reacts with oxygen, onto a material other than a metal such as cellophane, paper, glass, etc., by a vacuum deposition method or laminating with an adhesive.

When the metal used in the former material is used as a can material for food and beverage products such as canned beer, juice, canned food, surface treatment for cans such as iron alone, tin-plated steel plate, nickel-plated steel plate, chrome-plated steel plate, etc. Steel plates are used. In addition, any one of Fe, Zn, and Mn on the surface of the surface-treated steel sheet
Ultra-thin plating of one kind or two or more kinds (0.5 to 20 mg / dm ² ) is also a suitable metal material of the present invention. The above-mentioned metallic material may be further subjected to chemical conversion treatment such as phosphate treatment or chromate treatment. Aluminum can also be used as the metal material, but since aluminum itself has a stable oxide film formed on the surface, it does not react with oxygen or is extremely slow, so it is usually the above-mentioned F
It is used by plating with a metal having oxygen absorbing ability such as e, Zn, and Mn.

In the present invention, the coating composition used to form the hydrophilic coating layer applied to the surface of the metal material is not particularly limited as long as it forms a hydrophilic coating,
A water-soluble polymer is preferably used as a binder, and this is dissolved in water to form an aqueous solution having a solid content concentration of about 0.1 to 20% by weight. This composition is applied by a usual application means, for example, spray coating, and is naturally dried or heat dried. The hydrophilic coating layer may be formed not only once, but also twice or more by using the same composition or different compositions. The thickness of the hydrophilic coating layer is 0.01
-5 μm, preferably 0.05-1 μm. If the coating film thickness is less than 0.01 μm, the desired oxygen absorption effect cannot be obtained. On the other hand, if it exceeds 5 μm, rust is generated more than necessary and water resistance is deteriorated.

The "hydrophilic coating layer" in the present invention means a layer formed of a binder having a property of being easily dissolved or swollen in water at room temperature and having an affinity with water itself.

The water-soluble polymer used in the coating composition can be classified into natural type, semi-synthetic type and synthetic type.
Examples of natural polymers include starch, gelatin, casein, vegetable gums, and non-volatile residue of naturally occurring beverages. Examples of the semi-synthetic polymer include cellulose derivatives such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose and hydroxyethyl cellulose. Further, as the synthetic polymer, for example, polyvinyl alcohol, polyvinyl methyl ether, vinyl-based polymer such as polyvinylpyrrolidone, hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid, homopolymer such as methacrylic acid, the monomer and acrylic acid or Alkyl esters of methacrylic acid (eg methyl acrylate, ethyl acrylate, methyl methacrylate,
Examples thereof include copolymers with ethyl methacrylate), acrylic polymers such as polyacrylic amide, and water-soluble polymers such as polyethylene oxide.

Among the above water-soluble polymers, cellulose-based derivatives,
Above all, hydroxyethyl cellulose is a preferable polymer because it can impart excellent oxygen absorption ability to a metal.

If the coating composition forming the hydrophilic coating layer has the above-mentioned water-soluble polymer as a binder component, it sufficiently functions, but a water-soluble melamine resin or the like is added in addition to the water-soluble polymer. It is also possible to crosslink a part of the coating within a range that does not impair the hydrophilicity.

In the present invention, the above-mentioned hydrophilic coating layer may be applied to the entire surface of the metal material, or may be applied partially such as a lid or a bottom of a sealed container depending on the purpose.

The material having a deoxidizing function obtained in the present invention further has an oxygen / water permeable coating layer formed of polymethylpentene or polybutadiene on the hydrophilic coating layer described above.

The polymethylpentene or polybutadiene forming the oxygen / water permeable coating layer has a function of allowing oxygen and water to permeate well, and even if it comes into contact with the contents in the sealed container, a part of the film forming resin component is present. It is a resin that has properties such that it hardly migrates to the contents to impair the flavor property and permeates iron oxide ions generated on the metal surface.

As the composition for forming the oxygen / water permeable coating layer, in addition to the above-mentioned polymethylpentene or polybutadiene component, known pigments, extender pigments, colorants, plasticizers and the like can be added, if necessary. . In particular, by adding a silver pigment or the like to the pigment, it is possible to hide the rust generated on the metal surface. The composition forming the oxygen / water permeable coating layer may be an organic solvent dispersion type, powder type or film type.

The oxygen permeation amount q of the oxygen / water permeable coating layer formed in the present invention can be represented by the following formula.

In the formula, q is the amount of oxygen permeation (ml), P is the oxygen permeability coefficient of the resin ( ), Δp is the difference in oxygen partial pressure between the inside and outside of the film (mmHg), A is the film area (cm ² ), l is the film thickness (cm) and t is the time (sec).

The desired oxygen permeability of the oxygen / water permeable coating layer is such that the value of P (oxygen permeability coefficient of resin) is 10 ^{-10. Or} more, preferably 10 ^-9 It is preferable to have the above value.

The polymethylpentene forming the coating layer having the above-mentioned oxygen / water permeability is a kind of thermoplastic resin obtained by polymerizing 4-methylpentene-1 using propylene as a starting material, as is well known. It is the lightest thermoplastic resin commercially available in the past, and is also excellent in heat resistance, transparency, hygiene, and chemical resistance. Furthermore, its oxygen permeability coefficient is about 2.0 × 10 ^-7 It is a polymer with some characteristics such as being obtained as a larger numerical value than other polyolefins. It is usually used as a molded product such as extrusion or as a film.

On the other hand, polybutadiene is a syndiotactic 1,2-polybutadiene obtained by polymerizing butadiene, which is a thermoplastic polymer having an average molecular weight of 100,000 and a crystallinity of 15 to 30%, and is flexible and transparent. In addition to being high, it is excellent in food hygiene and safety. Its oxygen permeability coefficient is about 1.0 x 1
0 ^-9 Is a polymer showing. This is also used as an extruded product or a film.

(Function) The composition for forming the oxygen / water permeable coating layer used in the present invention is roll coating, spray coating, dipping method or the like in organic solvent dispersion type, fluid dipping method, electrostatic powder in powder form. In the case of a film such as a coating method, it can be applied by various methods such as thermocompression bonding or a film laminating method using an adhesive. When forming the oxygen / water permeable coating layer, fine concave portions and / or fine convex portions are formed in advance on the metal surface on which the hydrophilic coating layer is to be formed, and a gap is provided between the coating layer and the metal surface. You can also By doing so, the surface area of the metal surface can be increased, and at the same time, by encapsulating a substance that promotes oxidation in the gap, the oxygen absorption capacity can be further improved.

The thickness of the oxygen / water permeable coating layer formed on the hydrophilic coating layer is usually 5 to 500 μm, and preferably 10 to 200 μm.

The material having the deoxidizing function of the present invention can be used after being processed into a metal hermetic container or a non-metal hermetic container such as plastic, glass, and paper, or can be used as a crown or a cap. In particular, the material of the present invention is suitable as a metal hermetically sealed container for storing liquids such as beer, juice, and tea, which are mainly water, and prevents deterioration and alteration of the contents even during long-term storage, The quality can be maintained.

(Example) Hereinafter, the present invention will be specifically described based on Examples. In Examples and Comparative Examples, “%” means “% by weight”.

Example 1 A cold-rolled steel sheet having a thickness of 0.24 m / m was used as a base metal plate, and a hydrophilic coating composition containing a 3% aqueous solution of hydroxyethyl cellulose was first used, and the dry film thickness was reversed to 0.2 μm. After coating with a roller coater, baking was performed for 30 seconds in a hot air atmosphere at 200 ° C. to obtain a metal plate having a hydrophilic coating layer. Then, a polyurethane adhesive (Adcoat 506S manufactured by Toyo Morton Co., Ltd.) was coated on the same with a reverse roller coater so that the dry coating film had a thickness of 2 μm. And after drying and heating in a gas oven for 30 seconds so that the steel plate temperature becomes 200 ° C,
While keeping the temperature as it is, immediately use a roll laminator to bond a polymethylpentene film (TPX film X-45B manufactured by Mitsui Petrochemical Co., Ltd.) with a thickness of 50 μm, and immediately cool it to remove oxygen. A resin coated steel sheet having the above was obtained.

The obtained resin-coated steel sheet, the processing adhesion test shown below,
The performance was evaluated by a deoxidation capacity evaluation test.

Processing adhesiveness test: A # -type cross-cut having a width of 5 μm shown in JIS K-6744 was inserted from the film surface, and the presence or absence of film peeling at the time of processing the Erichsen test was observed.

Deoxidizing capacity evaluation test: Resin-coated steel sheet with a diameter of 65 mm
It was used as a lid for a 350 ml cylindrical glass container and was filled with beer so as to have a head space of about 24 ml and sealed. 20
After 30 hours at ℃, the oxygen concentration in the headspace and the oxygen concentration in beer were measured using a gas chromatograph.

The evaluation results are shown in Table 1.

Examples 2 to 4 Each of the base metal plates shown in Table 1 was bonded with a polymethylpentene film in the same manner as in Example 1 so as to have the respective thickness constitutions shown in the same table. A resin coated steel sheet having the above was obtained. The same test as in Example 1 was conducted using the obtained resin-coated steel sheet. The results are summarized in Table 1.

Examples 5 to 6 Polybutadiene films (JSR manufactured by Japan Synthetic Rubber Co., Ltd.) were applied to the respective base metal plates shown in Table 1 in the same manner as in Example 1 so as to have the respective thickness configurations shown in the same table. RB-8
A resin-coated steel sheet having a deoxidizing function, obtained by bonding 20), was obtained. However, the adhesive used was a modified polyolefin type (Rioflex # 3330 manufactured by Toyo Ink Mfg. Co., Ltd.).
The same test as in Example 1 was conducted using the obtained resin-coated steel sheet. The results are summarized in Table 1.

Comparative Examples 1 to 3 Resin-coated steel sheets were obtained in the same manner as in Example 1 such that the base metal plates shown in Table 1 had the respective thickness configurations shown in the same table. However, in Comparative Example 3, a polyethylene film (Idemitsu Petrochemical Industry Co., Ltd. # 0134M) was used. The oxygen permeability coefficient of the polyethylene film used here is about 5.0 × 10 ^-10 Is. The same test as in Example 1 was conducted using the obtained resin-coated steel sheet. The results are summarized in Table 1.

As can be seen from the results in Table 1, it can be said that the material according to the present invention efficiently absorbs oxygen and has a large capacity. If such a complex is used as a material for a container, the deterioration of the contents is prevented,
It is possible to make major improvements in terms of quality maintenance.

(Effect of the Invention) In the present invention, since the hydrophilic coating layer is formed on the surface of the metal material, oxygen and the metal cause a rapid oxidation reaction in the presence of water, and the oxygen absorption capacity is dramatically increased. When an oxygen / water permeable coating layer made of polymethylpentene or polybutadiene is formed on the hydrophilic coating layer, the rust (iron oxide It has a very remarkable effect of completely avoiding the influence of the) on the quality of the substance to be stored.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsunetoshi Asai 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel Co., Ltd. 1st Technical Research Laboratory (72) Inventor Tetsunaga Kida Dojimahama, Kita-ku, Osaka-shi, Osaka 2-chome 1-40 Suntory Co., Ltd. (56) Reference JP-A-61-295396 (JP, A)

Claims (2)

[Claims] 1. A deoxidizing function characterized in that an oxygen / water permeable coating layer formed of polymethylpentene or polybutadiene is provided on a hydrophilic coating layer provided on the surface of a metal material that reacts with oxygen. With material. 2. The material having a deoxidizing function according to claim 1, wherein the hydrophilic coating layer is formed of a cellulose derivative.