JPS61127455A - Falling cover material and method of sealing vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a drop-cover material obtained from a biaxially stretched thermoplastic resin film or sheet, and a method for sealing a container using the drop-cover material. be.

(Prior Art) Drop lids conventionally used for foods such as ice cream and somura have been vacuum-formed from general unstretched thermoplastic resin films. However, most of these were simply fitted onto the container. As a result, these containers have the disadvantage that their lids tend to come off during transportation, and that they do not have virgin properties at all. In addition, there is a method of using two-wheel stretched heat-shrinkable film as a lid that has adhesive properties, but with this method, it is difficult to make it into a concave shape, and the top of the lid shrinks due to the application of heat, resulting in a falling lid. 6 Furthermore, Japanese Patent Application Laid-Open No. 58-20620 discloses a method of creating a sealing material having secondary heat shrinkability by thermoforming a stretched film of two wheels, and causing the sealing material to undergo secondary shrinkage by heating. However, even with this method, it was not possible to obtain a fallen lid.

(Objective of the Invention) The present invention has virgin sealing properties and various studies have been conducted to see if it is possible to form a concave lid, and by adopting a partial heating method, the concave shape can be maintained by forming a heat-shrinkable film. The inventors discovered a method for obtaining a drop-cover material, and also completed a method for sealing a container using the drop-cover material to obtain a container with virgin properties.

(Structure of the Invention) The present invention provides a thermoplastic resin product characterized in that a flange part has heat shrinkability, a rising part has non-heat shrinkage property, and a bottom part has heat shrinkability or non-heat shrinkage property. A drop-lid material for a container, which is characterized in that the drop-lid material is placed on a container, and only the plunge part is heated, and the plunge part is contracted to seal the mouth of the container in a cap shape. This is a cancer sealing method.

In the present invention, a drop-cover material can be produced by partially heating only the rising portion of a drop-cover of a sheet, such as a biaxially stretched single-layer or composite film, and performing vacuum forming, pressure forming, compression molding, or the like. A method for producing a drop-cover material and a method for sealing a container using the drop-cover material of the present invention will be explained in detail with reference to the drawings.

In Figure 2, the biaxially stretched film (5) is
) is provided with a heater (6) that can be installed on the vacuum forming mold (7) having a heater (6) to heat only the portion that will become the rising portion (3) of the falling lid of the biaxially stretched film or the vicinity thereof,
The bottom of the drop lid (4) is a free holding plate (9).
), the part of the heat-shrinkable film that will become the plunge part (2) of the drop-cover material is mainly clamped, and the part that will become the rising part of the drop-cover material is heated and softened and vacuum-formed as shown in FIG. By trembling, as shown in Figure 1, from the plunge part (2) which has heat shrinkability, the rising part (3) which shows little heat shrinkability even when heated and stretched, and the bottom part (4) which has heat shrinkability. A drop lid material (1) is manufactured. In this case, instead of vacuum forming, the drop-cover material of the present invention can be similarly produced by air pressure, vacuum pressure air, or plug assist forming methods. The important point here is that only the rising part of the biaxially stretched film is stretched for forming, and the thickness of the plunge part (2) and bottom part (4) is almost the same as before forming. The heat-shrinkable film has a certain thickness, and the stretching properties of the heat-shrinkable film are maintained without any loss.

Another method for producing the drop lid material of the present invention is compression molding using a mold having a male mold (11) and a female mold (10), as shown in FIG. The two-wheel stretched film (5) is prepared in advance in the previous process by heating the part that will be the rising part (3) of the falling lid and the fitting part of the male and female molds to +30°C above the softening point of the biaxially stretched film. The biaxially stretched film (5) is placed on the female mold (10) and then the male mold (11) is preheated.
By cold-opening and pressurizing, only the preheated portion of the biaxially stretched film is stretched, and the plunge part (2) of the fall-cover material has the same heat-shrinkability as in the above method, and the non-heat-shrinkable riser. part (3) and a heat-shrinkable bottom part (4
) is obtained.

In both methods, the part to be preheated is only the rising part of the biaxially stretched film or the vicinity thereof, and if the bottom part is also preheated, the preheated part will shrink, leaving a hole. A product that can be used as a lid material cannot be obtained.

The preheating method in the present invention may be carried out using commonly used heating plates, far infrared rays, hot air, etc.

In addition, the two-wheel stretched film used in the present invention includes polyvinyl chloride, polyethylene, polypropylene, polystyrene,
A thermoplastic resin film made of a single layer of polycarbonate, polyethylene, etc. or a composite material using these materials, with a 1.0
A film stretched at a stretching ratio of 1 to 10 times is used.

As shown in FIG. 5, as an example of using the drop-cover material of the present invention, the container (13) containing the contents (12) is covered with the drop-cover material (1), and the top press plate ( 14) with the falling lid material (1
) while holding down the outer periphery of the container mouth (15). When the large protruding plunge part (2) is heated with hot air, etc., the plunge part (2) contracts and the container mouth becomes as shown in Figure 6. A drop lid (16) is formed that is in close contact with the part (15), and the container (13) is sealed.

The top press plate (14) used here needs to be kept at room temperature or below with cooling water or the like so that the bottom part (4) of the drop lid material does not shrink due to heat.

A completely sealed container can also be obtained by applying a hot-melt type or adhesive to the inner surface of the plunge part of the drop-cover material.

(Effects of the Invention) The drop-cover material of the present invention does not lose any heat shrinkability, which is a characteristic of biaxially stretched films, so even when sealing a container with the drop-cover material, the plunge portion shrinks when heated. Therefore, it is possible to obtain a drop lid that is in close contact with the mouth of the container. The drop lids obtained in this manner cannot be opened unless the drop lids are broken and can maintain sufficient virginity, and also have the effect that they can be stacked because of their concave shape.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the drop-cover material of the present invention, Figures 2, 3, and 4 are cross-sectional views showing a manufacturing apparatus for manufacturing the drop-cover material of the present invention, and Figure 5 is a cross-sectional view of the drop-cover material of the present invention. FIG. 6 is a cross-sectional view showing the container sealing method of the present invention, and a cross-sectional view of a container using a drop lid obtained according to the present invention. Patent applicant Sumitomo Bakelite Co., Ltd. Figure 1 Figure 4 Figure 5 Figure 6 Q, 17-

Claims (1)

[Claims] 1. Made of thermoplastic resin, characterized in that the flange part is heat-shrinkable, the rising part is non-heat-shrinkable, and the bottom part is heat-shrinkable or non-heat-shrinkable. A drop lid material for containers. 2. Covering the container with a drop-lid material made of thermoplastic resin, the flange part of which is heat-shrinkable, the rising part of which is non-heat-shrinkable, and the bottom part of which is heat-shrinkable or non-heat-shrinkable; A method for sealing a container, comprising heating only the flange portion and contracting the flange portion to seal the mouth portion of the container in a cap shape.