JPH01226502A - Method for producing sealed container - Google Patents

Abstract

PURPOSE:To reduce the improper sealing of a container such as staying water and the adhesion of its contents thereto, by forming the flange of a plastic container into a barrel-shaped configuration facing upwardly of the container and heat-sealing the flange and a lid to form the flat flange. CONSTITUTION:Although the barrel-shaped extension of a flange varies with the size and shape of a container and the width of its flange, the flange having a smooth curved surface free from square parts is desirable in order to effect a uniform sealing. In a container having an inside diameter of 70mm, a flange outside diameter of 82mm and a height of 30mm, for example, the curved surface of the flange of not less than 22R can bring a favorable sealing result. A container 1 having a barrel-shaped flange 3 is placed on a sealing stand 5, a lid 2 is than placed on the flange 3 and the lid 2 and the flange 3 are heat-sealed together by a hot sealing plate 4 under pressure to form a sealed container with a flat flange and a small variance of sealing strength.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a plastic container with good sealing properties.
! It concerns six methods of construction.

[Conventional technology]

Conventional sealing methods for sealed plastic containers have generally employed flat flange portions of the container body. However, when sealing with a flat seal plate, it is easily affected by variations in the thickness of the 7-lung part, the accuracy of the flatness of the seal plate, adhesion of contents, etc. This often resulted in incomplete sealing and poor appearance. For this reason,
In order to prevent these defects, a lot of effort and strict quality control were required before manufacturing the sealed container, such as increasing the accuracy of the thickness of the flange, increasing the accuracy of the flatness of the seal plate, and preventing overflow of the contents.

[Problem to be solved by the invention]

The present invention eliminates the risk of seal leakage in the heat sealing of plastic sealed containers, which has conventionally had safety problems with respect to seal leakage, and also eliminates the risk of air accumulation or adhesion of contents to the sealing part, and improves the appearance. Also a good container (q
As a result of our research, we found that a container with good sealing performance could be obtained by making the flange of the container body into a special shape.Based on this knowledge, we conducted various studies and completed the present invention. This is what I came to do.

(Means for Solving the Problems) The present invention has a flange portion of a plastic container main body formed in a drum shape facing toward the top of the container, and a cover body of the flange portion is heat-sealed. This is a method for manufacturing a sealed container, which is characterized by sealing the container so that it is flat.

The container main body used in the present invention is made of plastic, and its molding method is performed by known vacuum forming, pressure forming, blow molding, or injection molding.

As for the plastics forming the container body, in addition to general-purpose resins such as polypropylene, polyethylene, polystyrene, polyester, and polyvinyl chloride, multilayer sheets that take advantage of the properties of various resins can also be used.

The drum-shaped protrusion of the flange varies depending on the size and shape of the container, as well as the width of the flange, but for the purpose of uniform sealing, it is best to use a gently curved surface and an angular section on the flange. It is preferable that there is no.

For example, inner diameter 70φm, flange outer diameter 82φm, height 3
In a container with a diameter of 0 m, good results were obtained with a curved surface of 22 R or more by 1 d. On the other hand, if there are angular protrusions or dents on the flange, caution is required as this may cause adhesion of contents and accumulation of air, resulting in poor sealing.

Furthermore, the material of the lid used in the present invention may be the same as that of the container body, a film made of aluminum foil with an adhesive layer, or other multilayer films.

[For production]

As shown in FIG. 1, a container body 1 having a drum-shaped flange portion 3 is placed on a seal pedestal 5, and then a lid body 2 is placed on the flange portion 3, and a heated seal is placed on the container body 1. The lid body 2 and the flange portion 3 are crimped together using a disc 4, and the lid body 2 and the flange portion 3 are heat-sealed to form a sealed container.

The sealed container that has been bent in this manner has a flat flange portion, and the seal strength of the sealed portion has little variation.

+ -- inside ゛ 2↑ [Example] The present invention will be explained in detail based on an example (Example 1).
) Vacuum formed with multilayer sheet, opening diameter 80mm,
A multilayer container with a bottom diameter of 60 m and a height of 30 m was molded into a drum shape with a 50R radius with the flange facing upward.

Note that the inner and outer layers of the flange portion are made of polypropylene. A multilayer sheet with an ethylene vinyl alcohol copolymer arranged as a barrier layer in the middle was used, and then a multilayer film (PET/EUOH/PP, thickness configuration 12) was used as the top film.
PP was used as a seal.

Pudding was used as the content.

(Comparative Example 1) For comparison, a container with a flat flange portion and the same shape as in the example was made in other respects, the same contents as in the example were used, and the container was sealed using the same lid.

In the sealing method, both the seal group and the seal stand were flat, and the sealing temperature was 180°C.

100 each of the two types of sealed containers obtained according to the above
When 0 pieces were made and the condition of the seal part was checked, no seal failure occurred in the container with the drum-shaped flange shown in the example, and 20 seal failures occurred in the container shown in the comparative example. It was found that the sealed container according to the present invention maintains a good sealing condition.

(Effects of the Invention) According to the present invention, it is possible to obtain a container with a very beautiful appearance, and the causes of seal failure such as air pockets and adhesion of contents, which are conventional defects, are eliminated, so a sealed container can be obtained. It is suitable for creating.

For example, for jelly, pudding, water yokan, etc., containers were conventionally overfilled and filled 100% after the contents overflowed with a seal on the lid, but in conventional containers, the flange part Since the product is Furazo 1~, the contents may adhere to the flange, or uniform sealing pressure may not be applied to the flange, resulting in products with poor seals at times, and it is necessary to produce while considering the defective rate. However, according to the present invention, a high proportion of good products can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the sealing method of the present invention. Patent applicant: Sumitomo Bakelite Co., Ltd. No. 1rl
! J4 sticker board

Claims (1)

[Claims] (1) The flange of the plastic container body is formed into a drum shape facing the top of the container, and a lid is heat-sealed to the flange to seal the flange so that it is flat. A method for manufacturing a sealed container characterized by: