JPH078552B2 - Laminate 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. There is a method of absorbing and removing oxygen in the air in a closed container by wrapping it in.

(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,
In a can with a specific organic resin coating on the surface of a metal plate, oxygen in the contents easily permeates the organic resin coating and reacts very quickly with the metal plate, reducing the concentration in the contents It was found that the metal oxides formed did not penetrate the organic coating. At this time, when adhering the organic resin film to the metal plate, using a hydrophilic coating layer, at the same time, by dispersing or mixing a water-soluble polymer in the adhesive layer, it was found that a greater deoxidizing ability is given, The present invention has been completed.

That is, the present invention has an oxygen permeability coefficient of 10 ⁻¹⁰ via an adhesive layer in which a water-soluble polymer is dispersed or mixed on a hydrophilic coating layer formed on the surface of a metal material that reacts with oxygen. The present invention relates to a metal-resin laminate having a deoxidizing function, which is obtained by laminating the above oxygen / water permeable coating layers.

The metal-resin laminate having a deoxidizing function in the present invention includes a hydrophilic coating layer, a resin coating having a large oxygen permeability, an adhesive for attaching the resin coating to a steel sheet, and a reaction accelerator used as necessary. All materials except metal may be used, or plastic film, cellophane,
Metals that react with oxygen on materials other than metals such as paper and glass,
For example, a material obtained by applying a metal thin film of iron, zinc, manganese, or the like by a vacuum deposition method or laminating with an adhesive may be used.

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 laminate having a deoxidizing function obtained in the present invention has an oxygen permeability coefficient of 10 ⁻¹⁰ via an adhesive on the hydrophilic coating layer described above. The above oxygen / water permeable coating layer is applied.

For the adhesive used for this purpose, it is necessary to properly use the adhesive itself depending on the type and quality of the resin coating used as the oxygen / water permeable coating layer, but the resin component is generally polyester, polyurethane or poly Acrylate-based, modified vinyl-based, elastomer-based, olefin-based, modified olefin-based and the like can be applied alone or in a mixed form. If necessary, a polyisocyanate, a phenol resin, an epoxy resin, an amine compound or the like can be appropriately blended as a reaction curing accelerator.

As the water-soluble polymer to be dispersed or mixed in the adhesive, those used for the hydrophilic coating layer described above can be applied. Among them, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, vinyl methyl ether and polyvinyl alcohol and other vinyl derivatives. A system with added polymer gives a greater deoxidizing ability,
It is the preferred polymer. The amount of the water-soluble polymer is 1 to 200% by weight, preferably 5%, based on the solid content of the adhesive.
Used in the range of up to 100% by weight. If the amount of the water-soluble polymer is less than 1% by weight, it cannot be said that the oxygen scavenging ability is sufficient, and if it exceeds 200% by weight, the adhesiveness is deteriorated. As a method for dispersing or mixing the water-soluble polymer in the adhesive, the polymer may be dispersed to have a particle size of 100 μm or less, or a polymer dissolved in an organic solvent may be mixed.

The adhesive according to the present invention is applied by an ordinary means, for example, roll coating, spray coating and the like, and is naturally dried or heat dried. The thickness of the adhesive layer is 0.5 to 30 μm, and it can be applied in a range generally used, and is preferably 0.
The range of 5 to 10 μm is good.

Next, as the oxygen / water permeable organic resin film to be coated in the present invention, a usual plastic film can be used, but among them, the oxygen permeability coefficient is 10 ^−10. The above can be applied in a more preferable form. Specific examples include polymethylpentene, polybutadiene, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl chloride, polystyrene, polycarbonate and polyethylene. These films have a function of allowing oxygen and water to permeate well, and even when they come into contact with the contents in a sealed container, a part of the film-forming resin component migrates to the contents to impair the flavor property, or to prevent metal It is a resin that has the property of transmitting metal oxides formed on the surface very little. Among the resins mentioned above, polymethylpentene and polybutadiene have an oxygen permeability coefficient of 10 ^−7. It is at the level of and can be mentioned as a more preferable one. The oxygen / water permeable coating layer is usually applied as a film, but its thickness is 5 to 500 μm, preferably 10 to 200 μm.
Is the range.

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. It is preferable to have the above value.

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 average particle size as water-soluble polymer
Polyurethane adhesive containing 20% hydroxyethyl cellulose in an amount of 5% based on the solid content of the adhesive (Adcoat 506S manufactured by Toyo Morton Co., Ltd.) was applied to the reverse roller coater in the same manner as a dry coating of 2 μm. Painted. Then, after drying and heating in a gas oven for 30 seconds so that the steel plate temperature becomes 200 ° C., while maintaining the temperature as it is, immediately using a roll laminator, a polymethylpentene film with a thickness of 50 μm (Mitsui Petrochemical Industrial Co., Ltd. TPX film X-45BC, oxygen permeability coefficient of about 2.0 × 10 ^-9 Were bonded and immediately cooled to obtain a metal-resin laminate having a deoxidizing function.

The performance of the obtained metal-resin laminate was evaluated by the following processing adhesion test and deoxidation ability evaluation test.

Processing adhesiveness test: A # -type cross-cut having a width of 5 mm shown in JIS K-6744 was inserted from the film surface, and the presence or absence of film peeling during the processing of performing an 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 base metal plate shown in Table 1 was bonded with a polymethylpentene film in the same manner as in Example 1 so that each composition and thickness constitution shown in the same table were obtained. A metal-resin laminate having a function was obtained. The same test as in Example 1 was conducted using the obtained metal-resin laminate. The results are summarized in Table 1.

Examples 5 to 6 A polyethylene film (made by Idemitsu Petrochemical Industry Co., Ltd. #) was used in the same manner as in Example 1 using a cold-rolled steel plate as the base metal plate so that each composition and thickness constitution shown in Table 1 were obtained. 0134M, oxygen permeability coefficient about 5.0 × 10 ^-10 A metal-resin laminate having a deoxidizing function, obtained by bonding However, the adhesive used was a modified polyolefin type (Toyo Ink Mfg. Co., Ltd. Riofrex (LF)-# 333
0). The same test as in Example 1 was conducted using the obtained metal-resin laminate. The results are summarized in Table 1.

Examples 7 to 8 Polybutadiene films (JSR RB manufactured by Japan Synthetic Rubber Co., Ltd.) were used in the same manner as in Example 1 using cold-rolled steel plates as the base metal plates so as to have the respective compositions and thickness configurations shown in Table 1. -8
20, oxygen permeability coefficient about 1.0 × 10 ^-9 A metal-resin laminate having a deoxidizing function, obtained by bonding The adhesive used is the same as in Example 5. The same test as in Example 1 was conducted using the obtained metal-resin laminate. The results are summarized in Table 1.

Comparative Examples 1 to 5 Metal-resin laminates were obtained in the same manner as in Example 1, except that the metal plates shown in Table 1 had the respective layer configurations shown in the same table. The same test as in Example 1 was conducted using the obtained metal-resin laminate. The results are summarized in Table 1.

As can be seen from the results in Table 1, it can be said that the metal-resin laminate according to the present invention efficiently absorbs oxygen through the bonded resin film and has a very large ability. If such a laminated body is used as a material for a metal container, it is possible to prevent alteration of the contents and make a great improvement in 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. Further, since the adhesive layer in which the water-soluble polymer is dispersed or mixed on the hydrophilic coating layer also promotes the water absorbing ability, it brings about a further effect. And when the oxygen / water permeable coating layer is laminated, it does not reduce the oxygen absorption capacity, and
This has a very remarkable effect of completely avoiding the influence of the metal oxide generated by the oxidation reaction 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 (4)

[Claims] 1. A hydrophilic coating layer is provided on the surface of a metal material that reacts with oxygen, and an oxygen / water permeable coating layer is laminated on the hydrophilic coating layer via an adhesive layer in which a water-soluble polymer is dispersed or mixed. A metal-resin laminate having a deoxidizing function, characterized in that 2. A metal-resin laminate having a deoxidizing function according to claim 1, wherein the hydrophilic coating layer is formed of a cellulose derivative. 3. A metal-resin laminate having a deoxidizing function according to claim 1, wherein the water-soluble polymer to be dispersed / mixed in the adhesive layer is a cellulose derivative or a vinyl polymer. 4. The oxygen / water permeable coating layer has an oxygen permeability coefficient The metal-resin laminate having the deoxidizing function according to claim (1).