JPH0333564B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method of sealing a glass container, and particularly to a method of heat-sealing a glass container with a lid made of a laminated film laminated with a thermoplastic resin. [Prior art] Conventional methods for sealing glass containers include a method using a lip cap or crown, a method using an inner seal, and a method of heat sealing with a lid made of a laminated film laminated with thermoplastic resin. . In particular, heat sealing has recently been used in a wide range of applications due to its simple process and excellent sealing properties, but the adhesive strength is insufficient, so various improvement methods have been proposed. . One method for improving the heat sealing method is to select, as the thermoplastic resin, an ionomer, acid-modified polyolefin, EVA (ethylene vinyl acetate copolymer), etc. that has good adhesion to glass. However, even with this method, the adhesive strength is still insufficient. Another improvement method is to coat the heat-sealed portion of the glass container with a silane coupling agent or thermoplastic resin. Although it is certainly possible to improve adhesive strength with this method, it is not preferable for beverages and other items that are used by directly touching the glass, as the glass container itself is coated with a silane coupling agent. . [Problems to be Solved by the Invention] Thus, there has been a desire for a method of sealing glass containers using a heat sealing method that improves adhesive strength without coating the glass container itself with a silane coupling agent or the like. . That is, an object of the present invention is to provide a method of sealing a glass container by heat sealing, which makes it possible to improve adhesive strength without intervening any other material. [Means for Solving the Problems] The method of sealing a glass container of the present invention is a method of heat-sealing a glass container with a lid made of a laminated film laminated with a thermoplastic resin, the method comprising: consisting of heating the parts to a temperature of 400°C or higher and then heat sealing. The heating temperature of the heat-sealed portion of the glass container is preferably 400 to 600°C. Suitable thermoplastic resins to be laminated to the laminated film constituting the lid material include ionomers, acid-modified polyolefins, EVA, and the like, which have good adhesion to glass. [Function] According to the present invention configured as described above, the initial adhesive strength between the glass container and the lid material is improved, and the glass container can be sealed without any change in adhesive strength over time. The reason why excellent adhesive strength can be obtained simply by heating the heat-sealed part of the glass container is that the adsorbed water on the glass surface, which is thought to be the cause of the decrease in adhesive strength, is exposed to temperatures of 400°C or higher. This is thought to be because it is completely removed by heating. Heating temperature must be above 400℃, 400℃
At temperatures below .degree. C., it is not possible to improve the adhesive strength. The reason for this is that the water adsorption layer on the glass surface has two layers with different adsorption energies, and one adsorption layer can be removed by heating at 200 to 300℃, while the other adsorption layer can be removed by heating at 400℃ or higher. This is probably because it cannot be removed otherwise. Note that once the adsorption layer on the glass surface is heated to 400°C or higher, there is no need to maintain the temperature at 400°C or higher during heat sealing.
Furthermore, by heating at a temperature of 400°C or higher, not only the adsorption layer on the glass surface but also other contaminants are simultaneously incinerated and removed, which is also thought to contribute to the improvement in adhesive strength. Conventionally, there are cases where glass containers are heated to 70℃ before heat sealing, but this heating is to improve heat sealability, and at such a low heating temperature, water on the glass surface The adsorption layer cannot be removed, and the adhesive strength cannot be improved. An embodiment of the present invention will be shown below. [Example] Glass container made of soda lime glass (trademark:
S1214 (manufactured by Matsunami Glass Co., Ltd.) was heated with a gas burner until it reached 400°C, and the opening was heat-sealed with a laminated film. As the laminated film, a laminated film consisting of the following two types of Al foil and a thermoplastic resin layer was used. (1) Al (50μ)/Ionomer (50μ) (Trademark:
H1702, manufactured by Mitsui Polychemicals) (2) Al (50μ) / acid-modified polyethylene (50μ) (trademark: N410, manufactured by Mitsui Polychemicals) Heat sealing was performed at a temperature of 250℃ and a pressure of 3Kg/cm ² for 1 second. . Then, the adhesive strength immediately after heat-sealing and after being stored for one week and one month under the following storage conditions were measured. Storage conditions (1) Temperature: 25°C, humidity: 60% (2) Temperature: 40°C, humidity: 90% Adhesive strength was similarly measured without heating before heat sealing. The results are shown in the table below.

〔effect〕

As explained above, according to the glass container sealing method of the present invention, by heating the heat-sealed portion of the glass container to 400°C or higher before heat-sealing,
The water adsorption layer and contaminants present on the glass surface are completely removed, and as a result, glass containers can be heat-sealed with lids made of laminated film with high adhesive strength and without deterioration of adhesive strength due to changes over time. It is. Further, in the present invention, since no silane coupling agent or the like is applied to the opening of the glass container, it is extremely hygienic.

Claims (1)

[Claims] 1. A method of heat-sealing a glass container with a lid material made of a laminated film laminated with a thermoplastic resin, the heat-sealing portion of the glass container being heated to a temperature of 400°C or higher, and then heat-sealing. A method of sealing glass containers consisting of sealing. 2 The heat seal part of the glass container is 400 to 600
2. A method according to claim 1, wherein the method is heated to <0>C.