JPS5993605A - Method of sealing cuppy thin 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 The present invention relates to a method for filling a seamless, thin-walled plastic container with a filler and sealing the mouth of the container with a double-seam aluminum lid.

An object of the present invention is to provide a sealing method using a double-seamed aluminum lid, which has not been previously used as a sealing method for a seamless pot-shaped thin-walled container.

Double-seam aluminum lids have good sealing properties, are easy to open, and have a clean opening after opening, so they are used as lids for metal cans such as juice cans and water yoke cans. It is often used as. In addition, double-seam aluminum lids have already been commercialized as lids for thin-walled plastic containers for containers with conventional seams, but their development for seamless containers has lagged behind. The reason for this is that for seamless containers, a thick sheet must be used to form the deep-drawn container, which results in a thin body but a thick flange. Due to this thickness, the double seam aluminum lid cannot be tightened. On the other hand, for containers with seams, the body is formed by rolling a thin sheet into a cylindrical shape, so even in deep containers, the flange can be made thinner as well as the body, which makes it possible to wrap a double-seam aluminum lid tightly. However, in deep containers with seams, the joints are weaker than other parts, so accidents related to this cannot be completely eliminated.In general, resins with low heat resistance such as polyvinyl resin and polystyrene resin are used. No, it could not be used at high temperatures and was not suitable for hot filling or retort applications. The present inventors conducted various studies to create a seamless plastic container with good heat resistance and a double seam aluminum lid, and as a result, they arrived at the present invention. The present invention provides a depth to aperture ratio of at least 1.
In the above, a single layer or multilayer sheet mainly made of polypropylene resin is preheated to a temperature below the melting point of the polypropylene resin, and then molded, and the flange portion of the container is forged to at least 50% or less of the original thickness of the sheet. A pot-shaped thin container having a thickness of 1.0 times or less and having a middle part of the side wall slightly smaller than the upper part of the side wall of the container is prepared in advance so that at least the area where the diameter changes from the upper part of the side wall to the middle part of the container is The bottom of the container fits snugly into the concave holding tool that is located halfway in the height direction, and after filling the container body with the contents, close the double-seam aluminum lid. It is characterized by being covered and tightened using a tightening machine.

The present invention will be explained below with reference to the drawings. FIG. 1 shows the relationship between the thin-walled plastic container used in the present invention and the tools used to wrap double-seam aluminum around it. (1) and (
1 is a container used in the present invention, (2) is a concave holding tool used in the present invention, (3) is a double seam aluminum lid, and (4) is a concave holding tool used in the present invention.
) is a chuck, (5) beam lid 1 (6) is a first tightening roll, and (7) is a second tightening roll.

The shape of the container (1) is characterized in that the middle part of the side wall is slightly smaller than the upper part of the side wall. Container (1/l shape is container (1/l)
), the middle part of the side wall is composed of at least four columnar lips in the depth direction and a flat surface divided by the lips, and the lower part of the side wall is smaller and smaller than the middle part of the side wall. It is distinctive in that the bottom is concave toward the inside. The thickness of the flange portion of the container (1) and the container (1) is 1 mm or less.

Containers (1) and (11) are made from thick sheets of 1.5 or more rows.
In order to obtain a molded article having a shape like 'l', it is possible to mold it by the method disclosed in, for example, Japanese Patent Application Laid-Open No. 56-118812. In order to keep the flange thickness at least 50 inches below the original thickness of the sheet and below IB in absolute thickness using this method, the sheet temperature must be raised during molding to a level that does not affect other performance. is preferred. However, if the sheet temperature is too high, transparency and gloss will be poor, and if the sheet temperature is too low, moldability will be poor. When Tm is the melting point of polypropylene, it is most preferably about (Tm-10) ±3°C.

The higher the forging pressure applied to the upper and lower annular forging dies, the better.
A pressing force of at least 50 kf/cr71 is required. However, when the pressing force is increased, the clamping force of the molding equipment affects the upper shell, the equipment, the mold, and the cost of the product. In order to reduce the thickness of the 7-lunge without increasing the pressing force, for example, increase the mold temperature of the upper and lower annular forging dies, or use a material whose surface is not a good thermal conductor and is strong, such as plastic or plastic (mineral material, plastic). Preferably, composite materials such as metals are used. The containers having shapes (1) and (1) thus obtained are filled and sealed as follows. 1st
In the figure, a concave holding tool (2
) and place the container snugly inside. Next, fill the contents. Filling conditions include whether the temperature of the contents is room temperature or heated (60 to 95°C), and whether or not a head base is provided. The temperature of the contents may vary, but they can be broadly classified into these two types. The head space plays the role of not spilling the contents during filling and opening, and making heating, cooling, and stirring more efficient.

Next, cover the aluminum lid (3), and the lifter will go up and the chuck (4) will fit into the recessed part of the aluminum lid (3). Next, the first
o - # (5) approaches, advances a certain stroke amount while rotating, and then retreats. At this time, the chuck (3), lifter (5), container (1) or (f), holding tool (
2) also rotates. Next, the 20th rule (7) is the 10th rule (
Move forward and backward in the same way as in 6) to complete the seaming, and then remove the lifter (5).
) is lowered and the container (1) or (1') with the aluminum lid (3) is taken out. FIG. 2 is a cross section of a double seam portion of a double seam aluminum lid. (a) is only the aluminum lid, (b) is when the aluminum lid is placed on a pot-shaped thin container, (cl) is after seaming when the flange thickness is 1 mm or more, (C2) is when the 7 flange thickness is 17rrjn The cross section after seaming is shown in the following cases. In FIG. 2, (C1) cannot form a complete double seam. This is because the flange thickness is too thick, making it somewhat impossible to deform the flange during seaming. This may cause the lid to come off when pressure builds up in the container. On the other hand, in the case of (C2) where the 7-lunge thickness of the container is less than one loaf, the double seam is complete. In this case, the flange can be deformed, and the lid will not come off even if pressure is applied because of the double seam. If you apply more pressure, the sol top will eventually come off. Therefore, in order to achieve good seaming, the flange thickness must be 11 rrIn or less.

Next, when tightening, if the holding tool (2) is not used with the container (1) or (wa) shape, the tightening force will be directly transmitted to the container body.
Deformation of the torso, mainly dents. Holding tool (2)
When using this method, the tightening force is transmitted to the holding tool from the part where the diameter changes from the upper part of the side wall to the middle part of the container, so no deformation occurs in the body of the container. Also, if the diameter of the upper part of the side wall and the middle part are the same, the holding tool is useless, and the tightening force is transmitted to the body and creates a dent. Therefore, in order to prevent the container from deforming during seaming, the shape of the container must be such that the middle part of the side wall is slightly smaller than the upper part of the side wall, and a holding tool that fits this shape must be prepared in advance, and the container must be held in place using this tool. It is effective to put it in place completely and then tighten it.

Further consideration of the filling conditions reveals that container (1) is good when filled at room temperature regardless of the presence or absence of a head space. In the case of hot filling, only the case without head space is good, and with head space, dents are formed in the container body due to cooling. This is due to the reduction in pressure caused by the cooling of the air and water vapor in the headspace. Container (1 is good in all cases.

Even in the case of hot filling with a head space, the flat part of the middle part of the side wall of the container deforms to absorb the reduced pressure, and the columnar rib part does not deform, so the dents are not noticeable. Furthermore, when these containers are subjected to retort processing, if the container is of shape (1) and has no head space, the bottom tends to bulge, and if it is noticeable, the bottom periphery will float, making it unstable. If there is a headspace, the dent in the fuselage during heat filling and cooling will remain as is. On the other hand, the shape (in one container, deformation does not occur or is not noticeable after retorting regardless of whether there is a headspace). This is because the concave portions in the space and the bottom function as a reversible cushion against pressurization.

As described above, in order to perform good seaming, the thickness of the flange of the container 7 is 1.0 or less, and the middle part of the side wall is slightly smaller than the upper part of the side wall11). Prepare a holding tool in which the area where the diameter changes from the top of the side wall to the middle part is wide, and the bottom of the container is located midway in the height direction inside the tool, and hold the container in this tool. It is effective to fit it snugly and tighten it. Furthermore, when carrying out hot filling and retort processing, the shape of the container shown in Fig. 1 (1) is effective. Therefore, it has excellent transparency and rigidity, and can be molded at high speed.Furthermore, according to the method described in JP-A-56-118812, there is less scrap, so it can be molded at lower material costs.

The above results can be applied not only to a single layer of polypropylene but also to a multilayer structure such as polypropylene/adhesive layer/ethylene vinyl alcohol copolymer/adhesive layer/polypropylene, in which case gas barrier properties are excellent.

In this way, when the seamless plastic thin-walled plastic container of the present invention is sealed, it is lightweight, easy to process, transparent, heat-filling retort processable, long-term storage, easy to open, and clean when opened. Because of these advantages, it can be used for various food applications.

Example 2 Molding of shapes (1) and (r) using a polypropylene sheet of adjusted thickness and a polypropylene/adhesive polypropylene/ethylene vinyl alcohol copolymer/adhesive polypropylene/polypropylene sheet of 2-thickness did. The molding method was based on the method described in JP-A-56-118812.

Molding temperature: 155±2℃, blow pressure = 5, needle d Molded product size: Inner diameter 60mm, depth 100mm Flange thickness is adjusted by adjusting the pressure of air supplied to the upper mold moving air cylinder. Ta. The double seam aluminum lid has an outer diameter of 6 before seaming.
The 9Φ all-around open type was used, and the seaming machine was a hand seamer made by Yaro Iron Works ■. A laboratory autoclave was used for the retort treatment. Processing conditions were 100°C x 30 minutes x 1 hour gauge pressure.

Comparative Examples 1.2 and Examples 1 to 6 are shown in Table 1.

Table 2 shows the results of retorting Examples 3 to 6.

Table 2 shows polypropylene single layer and polypropylene/[5
There was no difference in the results between the molded products of 1 polypropylene/ethylene vinyl alcohol copolymer/adhesive polypropylene/polypropylene multilayer sheet.

[Brief explanation of drawings]

FIG. 1 shows the relationship between a thin-walled plastic container used in the present invention and a tool used to tighten a double-seam aluminum lid onto the container. In the figure, 1 and 1' are containers used in the present invention, 2 is a holding tool used in the present invention, 3 is a double seam aluminum lid, 4 is a chuck, 5 is a lifter, 6 is a first tightening roll, and 7 is the second tightening roll. FIG. 2 shows a cross section of a double seam portion of a double seam aluminum lid. (a) shows only the aluminum lid, (b) shows the state where the aluminum lid is placed over the cup-shaped thin-walled container, (C1) shows the cross section after tightening when the 7-lunge thickness is 1 inch or more, (C2 ) is the cross section after seaming when the thickness of the 7 langes is 1 mm or less. Patent applicant Sumitomo Bakelite Co., Ltd. Figure 1 (A) (C) 2
Figure (a) (b) (c+) (C2)

Claims (3)

[Claims] (1) A method in which contents are filled in a pot-shaped thin-walled plastic container and the mouth of the main body is sealed with a double-seam aluminum lid, the depth-to-aperture ratio is at least 1 and the main material is sb, polypropylene resin. A single-layer or multi-layer sheet is preheated and formed at a temperature below the melting point of the polypropylene resin, and the flange part of the container is forged to at least 50q6 or less of the original thickness of the sheet and has a thickness of 1.0 M or less,
A cup-shaped thin-walled container having a smaller shape than the upper part of the side wall of the container is fitted in advance so that at least the area where the diameter changes from the upper part of the side wall to the middle part of the container is widened. Place the container in a concave holding tool with the bottom part located halfway in the height direction, fill the container body with the contents, cover with a double seam aluminum lid, and tighten with a seaming machine. A method for sealing a thin-walled container characterized by the following. (2) A method for sealing a thin-walled container according to claim (1), wherein the multilayer sheet is composed of polypropylene/adhesive layer/ethylene vinyl alcohol copolymer/adhesive layer/polypropylene. (3) The cup-shaped thin container is 1. The middle part of the side wall is composed of at least four or more ribs in the depth direction and a flat surface divided by the ribs, and the middle part of the side wall becomes smaller in steps. A method for sealing a pot-shaped thin-walled container according to claim (1), which has a lower side wall having a bottom portion concavely facing inward.