JPH0155091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a thermoplastic synthetic resin lid whose opening portion can be easily cut out.

[Prior Art] Since rigidity is required for synthetic resin containers and the synthetic resin lids used for the containers, recently, thermoplastic synthetic resins with relatively high rigidity such as polypropylene have been used. Container bodies and lids are increasingly manufactured.

This sealed container with a container body and a lid made of synthetic resin is manufactured by injection molding or vacuum forming, etc., and the lid is punched into an appropriate shape from a sheet, or the lid is vacuum-formed after punching. The bodies were sealed together using heat sealing, etc. to form a sealed container.

[Problem to be solved by the invention] By the way, for example, polypropylene resin not only has high rigidity but also high toughness, so it is ideal as a container material, but when used as a lid, it is easy to cut and open. There are some disadvantages.

For this reason, in the past, the adhesive strength between the lid and the container body was generally adjusted so that the lid could be peeled off from the container mouth at the heat-sealed part when opening. It has been difficult to ensure a tight seal between the two and to allow the package to be tightly sealed so that it can be opened easily with a small amount of force.

[Means for Solving the Problems] The present invention provides a cutting recess having a substantially acute triangular cross-sectional shape and a required annular shape in the lid body,
In addition, a lid body made of thermoplastic synthetic resin is manufactured that forms a reinforcing ring body on both the inner and outer circumferential sides above the cutting recess, and the lower annular body has a triangular cross section with an acute angle at the lower end of the pressurizing hot plate. After heating the surface temperature of the protrusion to the melting temperature of the thermoplastic synthetic resin that will become the lid, the lid or lid material is placed on the top surface of a flat pressure receiving jig, and then the pressure dimension control ring is used to apply pressure. Adjusting the lowermost position of the hot plate to press the lower protrusion against the lid material etc. for a short period of time,
An annular recess corresponding to the cross-sectional shape of the lower projection is formed on the upper surface of the lid so that the remaining thickness of the lid material at the bottom of the annular recess is one-half or less of the thickness of the lid; When forming the recess, the synthetic resin melted by the downward protrusion is heaped up on both the inner and outer circumferential sides of the annular recess, thereby forming an inner reinforcing ring and an outer reinforcing ring on both the upper inner and outer circumferential sides of the annular recess, respectively. This is a method of manufacturing a lid made of thermoplastic synthetic resin, characterized in that:

[Function] Since the present invention heats the annular lower protrusion having a triangular cross section to the melting temperature of the synthetic resin lid and bites it into the lid, it is possible to easily form an annular groove in the lid. Since the amount of descent of the pressurizing hot plate is adjusted by the pressurizing size regulation ring, when the annular downward protrusion is lowered, a certain gap is left between the tip of the annular downward protrusion and the top surface of the pressurizing jig. The lower protrusion can be lowered in a similar manner, and a thin section for cutting can be easily formed on the lid body or the like.

In addition, the annular lower projection has a triangular cross section with an acute angle at the lower end, and since it is heated to the melting temperature of the synthetic resin, the lid body can be easily melted by a short period of strong pressure while melting the synthetic resin. Because the contact time between the lid and the protrusions is short, the lid or the synthetic resin of the lid material melts only at the contact area with the protrusions, and this molten resin is absorbed by the protrusions. It is pushed out to the left and right of the formed recess and bulges up, making it possible to easily form thick portions on both the inner and outer peripheral sides of the annular recess.

[Example] The present invention provides a lid with high rigidity and toughness,
Further, the invention relates to a method of manufacturing a lid made of thermoplastic synthetic resin that is easy to cut and open, as described below.

As shown in FIG. 1, a lid material 21 of a predetermined shape is placed on the upper surface of a pressure receiving jig 22 with a flat upper surface, and a Teflon sheet 20 for preventing adhesion is placed on the upper surface of the lid material 21. I'll put it on.

A pressurizing hot plate 18 that can freely press the lid material 21 from the upper surface of the Teflon sheet 20 is disposed, and the lower tip of the pressurizing hot plate 18 is attached to the lower surface of the pressurizing hot plate 18, as shown in FIG. A lower protrusion 1 having a predetermined annular shape and having a substantially triangular cross-sectional shape with an acute angle.
Set 9. In addition, a pressurizing dimension regulating ring 17 is attached to the pressurizing hot plate 18. Also, a means is provided to appropriately control the heating temperature and time of the pressurizing hot plate 18.

In the lid pressurizing device 16 as described above, the surface temperature of the annular lower protrusion 19 of the pressurizing hot plate 18 is set to 250°C.
Then, a polypropylene lid material 21 with a thickness of 0.25 mm was placed in a predetermined position on the pressure receiving jig 22, and a Teflon sheet 20 with a thickness of 0.07 mm was covered on the top surface.
The pressure dimension regulating ring 17 is used to adjust the gap between the pressure heat plate 18 and the top surface of the lid material 21 placed on the pressure receiving jig 22 to 0.17 mm, and the pressure heat is adjusted to 0.17 mm. The plates 18 are brought into strong downward pressure contact within a short time of 1 second. Then, while the heat sealing temperature of polypropylene is below 220℃,
The surface temperature of the lower protrusion 19 of the pressurizing hot plate 18 is 250℃
Since the temperature is higher than the melting temperature of the resin, the portion of the lower protrusion 19 that comes into pressure contact easily and quickly becomes molten. However, since the lid material is a relatively poor thermal conductor and the pressure contact of the protrusion 19 is for a short time, only the portion that the protrusion 19 is pressure contact with melts and the third
As shown in the figure, the cutting annular recess 25 is formed and the melted member corresponding to the annular recess 19 is attached to the lower protrusion 19.
Since it has an acute angle, it is easily pushed upward along the side surface, and the molten resin swells up on both the inner and outer circumferential sides of the upper part of the cutting annular recess 25. After the lower protrusion 19 rises, the molten resin solidifies and flows inside. A reinforcing ring 28 and an outer reinforcing ring 29 can be formed.

In the lid body 30 formed in this way, the bottom thickness of the cutting annular recess 25 is 0.1 mm, and the thickness of the other parts is 0.25 mm.
It is not only easy to cut because it is less than half the thickness compared to the 1/2 mm thickness, but also reinforcing rings 28 and 29 are formed on the inner and outer circumferential sides of the upper part of the recess 25. When a cutting tool such as a plastic knife is inserted into the recess 25 and then annular cutting is performed, the recess 25 is prevented from bending, making it easier to insert the cutting tool and advance the cut.

In another embodiment, instead of the flat lid material 21, processing is performed on a lid 31 that is vacuum formed into a desired shape using a polypropylene sheet with a thickness of 0.25 mm, as shown in FIG. The lid 31 is placed on the pressure receiving jig 22 having a flat upper surface on which the flat plate portion 33 excluding the peripheral edge 32 of the lid 31 is placed. In addition, the upper surface of the material of the lid body 31 has a thickness of 0.012 mm in advance.
Dry laminated with polyethylene terephthalate resin film. Then, after heating the pressurizing hot plate 18 to 230℃, the pressurizing force was set to 100Kg.
Pressure is applied for 1.0 seconds, and the recess 25 is formed as shown in Figure 5.
An annular cutting recess 25 with a bottom thickness of 0.1 mm is formed, and an inner reinforcing ring 28 and an outer reinforcing ring 29 are provided on both the inner and outer circumferential sides of the upper part of the recess 25.
A lid body 35 is manufactured.

Although the above-mentioned example describes a lid body mainly composed of polypropylene, the present invention is not limited to this. After heating the surface temperature of the lower protrusion 19 of the pressure heating plate 18 to temperature, the lid material 21 or the lid 31 is placed on the top surface of the flat pressure receiving jig 22, and then the pressure size regulation ring 17 is By lowering the pressurizing hot plate 18 by limiting its descending amount, the annular lower protrusion 19 having a triangular cross section with an acute angle at the lower end is brought into pressure contact with the lid material etc. for a short period of time and bites into the lid material. A cutting annular recess 25 having a cross-sectional shape similar to that of the lower projection 19 is formed on the upper surface of the material, and an inner reinforcing ring 28 and an outer reinforcing ring 29 are formed on both the inner and outer circumferential sides of the upper part of the annular recess 25, respectively. A method of manufacturing a thermoplastic synthetic resin lid body according to the present invention, wherein the cross-sectional shape of the annular recess 25 is substantially an acute triangle, and the bottom thickness thereof is one half of the thickness of the lid body.
The following and heated annular lower projection 19
The synthetic resin melted by the cutting annular recess 2
Since the lid made of thermoplastic synthetic resin has a structure in which the inner reinforcing ring 29 is formed by raising both the inner and outer circumferential sides of the upper part of the lid, the lid can be easily cut into the annular recess 25 for cutting.
This is a method that can easily manufacture such a lid because it can be cut along the .

[Effects of the Invention] The present invention limits the amount of descent of the pressurizing hot plate using the pressurizing size regulating ring, and also heats the annular lower protrusion having a triangular cross section so that it bites into the cover material. A thin-walled part for cutting can be easily formed by forming an annular recess in the body, and a thick inner reinforcing ring is formed on the inner and outer peripheries of this annular recess due to the swelling of the molten resin when the annular recess is formed. A method for producing a lid made of thermoplastic synthetic resin, which facilitates cutting at the annular recess in the lid and allows the container to be easily opened, since the lid forms an outer reinforcing ring. be.

[Brief explanation of drawings]

FIG. 1 is a side view of a lid pressurizing device used in the method of the present invention, FIG. 2 is a cross-sectional view of a pressurizing hot plate, and FIG. 3 is a cross-sectional view of a lid having a formed cutting recess. FIG. 4 is a lid pressurizing device showing a second embodiment, and FIG. 5 is a sectional view of a lid manufactured in the second embodiment. 16... Lid pressurizing device, 17... Pressurizing size regulation ring, 18... Pressurizing hot plate, 19... Lower projection, 20... Teflon sheet, 21... Lid body material, 22... Pressure receiver Jig, 25... annular recess for cutting, 28... inner reinforcing ring body, 29... outer reinforcing ring body, 30... lid body with cutting recess, 31...
Vacuum-formed lid body, 32... Peripheral portion, 33... Flat plate portion, 34... Pressure receiving jig of the second embodiment, 35...
...Lid manufactured according to the second example.

Claims (1)

[Claims] 1 After heating the surface temperature of the annular downward protrusion with an acute triangular cross section on the pressurizing hot plate to the melting temperature of the thermoplastic synthetic resin that will become the lid, place the lid or lid material on the top surface of the flat pressure receiving jig. Next, the lowermost position of the pressurizing hot plate when lowered is adjusted using the pressurizing size regulating ring so that the tip of the lower protrusion can be lowered to near the top surface of the pressurizing jig, and the lower protrusion is lowered. The lid body etc. is press-contacted for a short period of time to bite into the lid body, etc., to form an annular recess having a triangular cross section in accordance with the cross-sectional shape of the lower protrusion on the upper surface of the lid body etc., and when forming the annular recess, a downward The synthetic resin melted by the protrusion is heaped up on both the inner and outer periphery sides of the annular recess, so that the thickness of the bottom of the annular recess is one-half or less of the thickness of the lid body, and the upper inner periphery of the annular recess is 1. A method for manufacturing a thermoplastic synthetic resin lid, comprising: forming an inner reinforcing ring on the outer circumferential side of the upper part of the annular recess; and forming an outer reinforcing ring on the outer peripheral side of the upper part of the annular recess.