JPH0375136A - Laminate with deoxidation function - Google Patents

Abstract

PURPOSE:To enhance deoxidation capacity by dispersing and mixing one or more kind of active metal magnesium, zinc, lead, iron, nickel, tin and manganese between a metal material and an oxygen/water permeable coating layer. CONSTITUTION:Since deoxidation reaction is performed immediately inside an oxygen/water permeable film when a metal forming reaction through the reaction with oxygen is dispersed in an adhesive layer, said metal becomes a barrier against oxygen/water permeability and the effect of an adhesive layer, said metal becomes a barrier against oxygen/water permeability and the effect of an adhesive can be suppressed to the min. and deoxidation capacity can be enhanced. As the metal mixed with this inventive adhesive, magnesium, zinc, iron, nickel, tin and manganese are pref. All of these metals are selected because they are active to oxygen but an alkali metal active to oxygen such as sodium, potassium or calcium is not pref. because said metal is two violent in reaction and generates a large quantity of heat and makes the adhesive strong alkaline after deoxidation reaction to markedly reduce bonding strength.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention prevents the deterioration and deterioration of bottles, single-serving beverage cans, etc. by oxygen.
It is used as a material for sealed containers that store contents that are susceptible to deterioration, and is used in oxygen scavenging containers where the area of the oxygen scavenging laminate cannot be increased despite the large capacity of the lottery.

[Conventional technology]

Traditionally, canned foods used for long-term storage of beverages and food have been sterilized by heat and filled with nitrogen to prevent oxygen from entering the cans.

However, these methods are difficult to completely remove oxygen;
Recently, reducing substances are packaged and encapsulated in a transparent film, etc., and oxygen is consumed for oxidation of these reducing substances to prevent the contents from deteriorating. Furthermore, laminated metal bodies with oxygen scavenging ability are The invention of cans has attracted attention as a cheaper and more effective method.

In particular, the materials for creating this oxygen scavenging function are:
As seen in JP-A No. 63-274537, a polyolefin film such as polymethylpentene or polybutadiene with excellent oxygen and water permeability is bonded with an adhesive onto a hydrophilic coating layer applied to a metal material. things are used.

It is effective enough to prevent the contents of canned foods from deteriorating and maintain their freshness. However, in order to completely remove oxygen by supplementing heating deaeration, nitrogen sealing, etc., a better deoxidizing function may be required, especially for bottle caps where the area of the deoxidizing layer cannot be increased. , a material with greater oxygen scavenging capacity was needed.

(Means for Solving the Problems) Therefore, as a result of various studies in order to solve this problem, the present inventors found that the found that the oxygen scavenging ability could be improved by incorporating active metals.

That is, the present invention provides an oxygen-reducing functional metal-resin laminate in which an oxygen- and water-permeable coating layer is laminated on the surface of a metal material via an adhesive layer or the like. Metal magnesium, zinc, iron, nickel, tin,
The present invention relates to an oxygen absorbing laminate characterized in that one or more types of manganese are dispersed and mixed therein.

[For production]

In the present invention, an oxygen/water permeable layer is laminated on the surface of a metal material via an adhesive layer. In that case, a wood-loving coating layer may be applied to the metal surface. The wood-philic coating layer is formed from a binder that easily dissolves or swells in water at room temperature, and refers to a binder that itself has an affinity for water, including, but not limited to, a water-soluble polymer. An aqueous solution prepared by dissolving this binder in water and having a solid content concentration of about 0.1 to 20% by weight is preferable. Examples of water-soluble polymers include starch.

Examples include gelatin, cellulose derivatives, polyvinyl alcohol, acrylic acid, methacrylic acid, or their esters.

This metal material can be made active by pickling or polishing with a product such as Scotchbrite so that it can easily combine with oxygen.

Further, in the present invention, an oxygen/water permeable coating layer is laminated via an adhesive layer or the like. As the oxygen/water permeable coating layer, a polyolefin such as polymethylpentene or polybutadiene is used, which has high permeability to oxygen and water but does not allow metal ions to pass therethrough. The adhesive is polyester.

Polyurethane-based, polyacrylate-based, modified vinyl-based, elastomer-based, olefin-based, modified olefin-based, etc. can be used alone or in a mixed form. It is also possible to disperse or mix wood-philic or water-soluble polymers, ion exchange resins, etc. into the adhesive. It is also possible to apply the adhesive locally.

In particular, the present invention relates to an active metal-loaded adhesive layer between such a metal material and an oxygen/water permeable coating layer.

Originally, the deoxidizing function laminate allows oxygen and water in a sealed container to migrate through the coating layer, oxidizes the metal body on the hydrophilic coating layer, and fixes oxygen as metal oxide in the oxygen/water permeable coating. The purpose is to remove trace amounts of oxygen contained within the can.

However, since the metal body and wood-philic film necessary for the oxidation reaction are located inside the adhesive layer, which has relatively low permeability to oxygen and water, this has been a cause of deterioration of the oxygen scavenging ability.

For this reason, attempts have been made to incorporate water-soluble polymers into materials with good oxygen and water permeability, and to improve the adhesive itself. Although these efforts have had some effect, they are still required to have a high level of oxygen scavenging ability. However, this was still insufficient as a material for use in the manufacturing process, and further improvements were needed.

As a result of various studies, we found that if a metal that reacts with oxygen to form an oxide is dispersed in the adhesive layer, the deoxidizing reaction can be achieved with oxygen and water! Since the process is carried out immediately inside the permeable film, the influence of the adhesive, which acts as a barrier to oxygen and water permeability, can be minimized, leading to the idea that the oxygen scavenging ability will be improved. It's arrived.

Preferably, the metal to be mixed into the adhesive of the present invention is magnesium, zinc, iron, nickel, tin, or manganese. All of these metals were chosen because they are active against oxygen, and among the metals that are active against oxygen is sodium.

Alkali metals such as potassium and calcium are not preferred because they react too rapidly and generate a large amount of heat, and after the deoxidizing reaction, make the adhesive strongly alkaline, significantly weakening the adhesive force.

The metal of the present invention can be expected to form a local battery together with the metal body as a base material, and can also be expected to have the effect of promoting oxidation of the metal. Therefore, it is thought that a metal less noble than the base metal can exhibit a more effective effect. However, this is not necessary. This is because it is sufficiently effective even if it is close to an oxygen/water permeable film.

Expecting a similar effect, there is not only one type of metal, but 2F! It is also possible to mix metals of the same type or higher. It is also possible to use alloys of the above metals.

The shape of these metals may be lumpy or flaky, or needle-like or fibrous. In any case, it is necessary to disperse them as uniformly as possible to avoid agglomeration.

If it is in the form of lumps or flakes, even if it is too large, the oxygen scavenging capacity per unit weight will not increase, so it is meaningless;
m or less is appropriate. For the same reason, the diameter of needle-like or fibrous materials should be 100 μm or less. In particular, if the metal is too large, unevenness may occur on the surface of the oxygen/water permeable coating, but this is not a problem unless it is extreme.

When using long needle-like or fibrous metal, it is also possible to use a net-like shape.

Regarding the amount added, if it is too small, the oxygen scavenging ability will not improve at all, and if it is too large, the adhesive force will deteriorate. In the case of a similar condition, it is sufficient to add approximately this amount as a guide.

Usually, these metals are mixed into adhesives and applied.
The adhesive may be applied after the adhesive has been applied, or after the adhesive has been applied and insufficiently cured, it may be sprayed on or dispersed in a water-soluble polymer or a suitable solvent and applied. Approximately the same effect can be expected by applying a hydrophilic coating layer and mixing it therein or coating it thereon.

To disperse the adhesive into the adhesive, a lump, flake, needle, or fibrous metal is added and vigorously stirred, and the adhesive can be applied evenly by stirring while applying the adhesive. It is also effective to use a dispersant such as a silane type.

Further, if it is mixed inside the oxygen/water permeable film, problems such as adhesion can be prevented and the amount of metal mixed can be increased, which is more effective. For example, oxygen
The water-permeable film has a two-layer structure, and the upper layer is
It is also possible to use a water-permeable film or a modified film with improved adhesiveness as the lower layer, and to mix a metal into this modified film. Furthermore, it can also be dispersed between an oxygen/water permeable film and a modified film.

〔Example〕

Hereinafter, the present invention will be specifically explained based on Examples.

Example 1 A wood-loving coating composition consisting of a 3% aqueous solution of hydroxyethyl cellulose was first coated on a 0.24 mm thick cold-rolled steel plate using a reverse coater so that the dry plate thickness was 0.2 μm. A steel plate having a hydrophilic coating layer was obtained by baking in an atmosphere at 200° C. for 30 seconds. Next, 20% by volume of metal Zn powder with an average particle size of 5 μm (80% of 10 μm or less)
A polyurethane adhesive in which was dispersed was dried and coated to a thickness of 2 μm using the same reverse roller coater. Then, the steel plate was dried and heated in a gas oven for 30 seconds to reach a temperature of 200°C, and while the temperature was maintained, a 50 μm thick polymethylpentene film was immediately laminated using a rollator. It was immediately cooled to obtain a resin-coated steel sheet with oxygen scavenging function. Using the obtained sample as a sample, the following oxygen scavenging ability test and processing adhesion test were conducted.

(2) Oxygen scavenging ability test A resin-coated steel plate was used as the lid of a cylindrical glass container with a diameter of 65 mm and an internal volume of 350 mj2, and beer was poured into the container in a CO2 atmosphere containing 0.6 H2 so as to have a head space of approximately 24 mm and the container was sealed. (Referred to as test specimen A.) As a comparison material, a commercially available epoxy phenol resin paint for cans was applied to the same glass container to a film thickness of 60 B/dm2, and a dry No. 50 tin plate was used as the lid for baking. Beer was added and sealed under the same conditions as Body A.

(Referred to as test specimen B.) After keeping these at 20° C. for 24 hours, they were shaken well, the oxygen concentration was measured with an oxygen analyzer, and the oxygen scavenging ability was evaluated using the following formula.

(2) Processing adhesion test A 5 mm width #-shaped cross cut as shown in JIS K-6744 was placed in the film, and a 7 mm Erichsen test was conducted to observe whether or not the film peeled off after processing.

Example 2 A grain size of 4 μm (10 μm
A polyurethane adhesive in which 30% by volume of metallic Fe particles (hereinafter referred to as 75%) were dispersed was applied to a dry film thickness of 2 μm, and a 50 μm thick polymethylpentene was laminated using a roller laminator to prepare a sample. The above-mentioned oxygen scavenging ability test and processing adhesion test were conducted on this board.

Example 3 A 3% aqueous solution of hydroxyethyl cellulose was applied to a cold-rolled steel plate with a thickness of 0.24 au to a dry film thickness of 0.3 μm, and a polyurethane adhesive was applied on top of it to a dry film thickness of 2 μm.
Apply it so that it looks like this, and then use a roller laminator immediately.
A laminate of a 10 μm thick modified polymethylpentene film in which 20% by volume of metallic Zn powder with an average particle diameter of 5 μm (80% of 10 μm or less) was dispersed and a 50 μm polymethyl pentene was laminated. This sample was subjected to an oxygen scavenging ability test and a processing adhesion test.

Comparative Example 1 A 3% aqueous solution of hydroxyethyl cellulose was applied to a cold-rolled steel plate with a thickness of 0.24 mm to a dry film thickness of 0.3 μm, and a polyurethane adhesive was applied thereon to a dry film thickness of 2 μm. , 50A immediately with a roller laminator
t11 polymethylpentene was laminated. This sample was subjected to an oxygen scavenging ability test and a processing adhesion test.

Table 1 shows the evaluation results of each example and comparative example. Example 1 is a deoxidizing functional steel sheet produced by applying a wood-loving coating layer and adding metal zinc powder to the adhesive on top of the coating layer, and Example 2 is a steel plate with a deoxidizing function produced by applying a wood-loving coating layer and adding metal zinc powder to the adhesive. It is manufactured by applying it to a steel plate. Further, Example 3 was produced by laminating a layer of modified polymethylpentene containing metal Zn powder on a lower layer of polymethylpentene on a cold-rolled steel plate. Compared to the comparative example in which no metal is added, the deoxidizing ability is significantly improved to 70% or more.

At the same time, the processing adhesion properties of Examples 1 to 3 were almost the same as those of the comparative example.

(Effects of the Invention) The laminate of the present invention has a metal with an oxygen scavenging function placed as close as possible to the oxygen/water permeable film when viewed from the cross section, and effectively exhibits the oxygen scavenging ability. As shown in Figure 2, it exhibits excellent oxygen scavenging ability, and therefore, an oxygen scavenging functional container made using this laminate also has better effects than conventional ones.

4 others

Claims (1)

[Claims] 1. In a metal-resin laminate with an oxygen-removing function in which an oxygen- and water-permeable coating layer is laminated on the surface of a metal material,
An oxygen scavenging laminate characterized by having a metal active against oxygen dispersed and mixed between the water-permeable coating layers. 2. The deoxidizing functional laminate according to claim 1, wherein a metal active against oxygen is mixed into the adhesive. 3 Magnesium is a metal that is active against oxygen. The oxygen scavenging functional laminate according to claim 1 or 2, characterized in that it contains one or more of zinc, iron, nickel, tin, and manganese.