JPS6154587B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lid material for a hermetically packaged glass container.

In general, liquid or liquid-like foods such as jam, juice, alcoholic beverages, and mayonnaise are packed into glass containers, and then either a metal cap is caulked, a screw cap is screwed onto the screw opening, or a screw cap is screwed onto the opening. It was sealed and packaged using an aluminum crown. However, in this case, there were disadvantages such as poor sealing performance, difficulty in removing the lid when opening the package, and high cost.

Recently, the opening of a glass container is coated with a metal oxide layer and then a thermoplastic resin layer, or the metal oxide coating layer is coated with a silane coupling agent layer and a thermoplastic resin layer. A method has been proposed in which the lid material is tightly attached to the mouth of the container by heat sealing (Japanese Patent Application Laid-Open No. 1983-1999).
(See Publication No. 20651). However, in this case, when the container is opened, a portion of the resin from the lid material remains at the mouth of the container, spoiling the appearance, and the above-mentioned coating process of the glass container causes poor container productivity and high costs. Ta. In addition, in the case of powdered foods, a method was used in which a lid was glued to the mouth of the container, but this method had disadvantages such as the lid being difficult to peel off when the container was opened, and glue remaining on the mouth. Ta.

By the way, for plastic containers, it is common to use a sealing method in which a lid material made of a laminate of, for example, aluminum foil and a thermoplastic resin film is adhered to the mouth of the container by heat sealing. However, when this method is applied to containers made of soda-lime glass, the initial adhesion between the glass and the polymer may be insufficient, and the adhesion strength gradually decreases, especially in the case of liquid filling, resulting in sealing within a few days after sealing. There was a problem with the loss of sexuality.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide a lid material for a hermetically packaged glass container that has excellent sealing properties, is easy to open, and can be manufactured economically.

The lid material according to the present invention is a lid material for a glass container having a metal oxide coating layer, and is made of a copolymer resin of ethylene and an α,β-ethylenically unsaturated carboxylic acid. The content of saturated carboxylic acid is 5-15% by weight, and the content of carboxylic acid groups is 0.5-15% by weight.
A film made of resin, 40% of which is neutralized with metal ions, is laminated on one side of metal foil.

Glass containers for sealed packaging are generally made of soda lime glass. The glass container used is one in which a coating layer of metal oxide is formed on the surface of the container by spraying metal compound vapor at a temperature of 450 to 650°C after it is molded and before being placed in a slow cooling furnace. It will be done. As the metal compound, a tin compound such as tin tetrachloride or dimethyltin dichloride, a titanium compound such as titanium tetrachloride, or a zirconium compound such as zirconium tetrachloride is used.

As the α,β-ethylenically unsaturated carboxylic acid, acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, maleic acid, fumaric acid, etc. are used. Monoesters and acid anhydrides of dicarboxylic acids such as maleic acid and fumaric acid can also be used as the α,β-ethylenically unsaturated carboxylic acids in this invention. The reason why the content of α,β-ethylenically unsaturated carboxylic acid in the copolymer is limited to 5 to 15% by weight is that if it is less than 5% by weight, it is too high to the melting point of the resin, resulting in poor heat sealability at low temperatures. To,
Adhesion with glass containers deteriorates, and on the other hand, 15% by weight
This is because, if the melting point of the resin is too low, the adhesive force immediately after heat sealing will be weak, and products with poor adhesion will likely be produced.

Monovalent, divalent and trivalent metal ions are used as neutralizing metal ions. In particular, when Zn ions are used, the moisture absorption rate of the resin is slow and the saturated moisture content is low, so the migration of moisture to the seal interface after heat sealing is suppressed and the seal strength does not decrease. Na ions are not preferred because they tend to reduce seal strength.

The reason why the degree of neutralization of α,β-type ethylenically unsaturated carboxylic acid by metal ions is limited to 0.5 to 40% is that if it is less than 0.5%, the advantages of ionic copolymer resins, such as low-temperature heat sealability, This is because the extremely good sealing properties and oil resistance are not fully demonstrated, and on the other hand, if it exceeds 40%, the moisture absorption rate is fast and the saturated moisture content becomes high.

The thickness of the film made of ethylene ionomer is, for example, 20 to 100 μm.

Aluminum foil is commonly used as the metal foil. The thickness of the aluminum foil is 20 to 100 μm, preferably 40 to 60 μm.

The film is laminated onto the metal foil using an adhesive such as a two-component polyester-isocyanate reactive adhesive, or by melt-pressing the film onto the metal foil without using an adhesive. When filling with a highly corrosive filler such as dressing or mustard, an epoxy resin layer is provided on the inner surface of the aluminum foil to prevent deterioration of the adhesion of the film to the aluminum foil. Further, a printed layer is provided on the outer surface of the aluminum foil, if desired, and a waterproof coating is further applied thereon.

Since this invention is configured as described above,
The following effects are produced.

1. Heat sealing can be done at low temperatures and in a short time.

2. Since the water resistance of the sealed portion is taken into consideration for both the glass container and the lid material, the sealability of the hermetically packaged glass container is extremely good.

3. Since it is necessary to tear the lid material to remove the filling, it becomes obvious whether or not the container has been tampered with by looking at the lid material, thereby ensuring the safety of the packaging.

4. There is no need to apply a resin coating to the mouth of the glass container, and the container can be produced using the normal manufacturing method for glass containers, so productivity is higher than that of conventional sealed packaging glass containers using the heat-sealing method. It is possible to reduce costs.

Example: A container made of soda lime glass with a volume of 200 c.c. is formed in a mold and heated to a temperature of 450 cc before being placed in an annealing furnace.
The vessel was sprayed with tin tetrachloride vapor at ~650°C. In this way, a large number of test vessels having tin oxide coating layers on their surfaces were manufactured.

A 50 μm thick aluminum foil with a printing layer on one side and a waterproof coating layer on top, and a layer of ethylene ionomer on the other side.
A 50 μm film was laminated via an adhesive. The ethylene ionomer was an ethylene/methacrylic acid copolymer resin with a methacrylic acid content of 10% by weight and 10% of the methacrylic acid groups neutralized with Zn. In this way, a lid material was obtained.

A large number of glass containers obtained as described above are each filled with hot water at a temperature of 90°C at a filling rate of 70%, and the mouths of the containers are heat-sealed at a temperature of 210°C for 1.5 seconds at 160 kg/piece using the above lid material. did. The numerous hermetically sealed glass containers thus obtained were left inverted at room temperature. No liquid leakage from the seal was observed in any of the containers even after 4 months had passed, and there was no decrease in the adhesive strength between the mouth and the lid.

Comparative Example 1 The same operation as in Example was repeated, except that an ethylene ionomer containing 10% by weight of methacrylic acid and 40% of the methacrylic acid groups neutralized with Na was used.

30 of all test containers one month after heat sealing
% of the seals were damaged, resulting in liquid leakage. In addition, the adhesive strength between the mouth and the lid of the remaining containers decreased.

Comparative Example 2 The operation of Example 1 was repeated except that a glass container without a tin oxide coating layer was used.

The seals of all containers were damaged within one round after heat sealing, and liquid leakage occurred.

Claims (1)

[Claims] 1. A lid material for a glass container having a metal oxide coating layer, which is a copolymer resin of ethylene and α,β-ethylenically unsaturated carboxylic acid with a content of α,β-ethylenically unsaturated carboxylic acid. A lid material for a glass container for sealed packaging, comprising a film made of a resin in which the carboxylic acid groups are neutralized in an amount of 5 to 15% by weight and 0.5 to 40% with metal ions, and laminated on one side of a metal foil.