JPH03650A - Synthetic resin sheet molded item such as vessel and lid, and molding thereof - Google Patents

Abstract

PURPOSE:To obtain excellent strength, heat-retaining property, sealing ability and tightness when a molded item is covered with a lid by a method wherein on a part of or a whole inner periphery of a rising part such as a side wall of a molded item such as a vessel and a lid, a protrusion made more expandable than other parts of the rising part is formed and a groove is formed between the protrusion and a flat part. CONSTITUTION:On the inner periphery of a lengthwise side wall part 12a of a side wall 12, a protrusion 13 protruding opposite directions is provided close to the end wherein this protrusion 13 is formed to be more expandable than other parts of the side wall 12. A groove 14 is provided between the protrusion 13 and a flat part 11. Thus the groove 14 can be engaged with a peripheral part (a) of a package A. The flat part 11 is provided with a stage directing upward close to the outer periphery so that the strength against bending deformation. The entire body of this lid 1 is formed of a laminated sheet S wherein non-expandable thermosetting synthetic resin film F is bonded to both faces of an expandable resin sheet S'.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to molded products such as containers and lids made of foamed resin sheets or synthetic resin sheets laminated with non-foamed resin films, and methods for molding the same.

<Prior art and problems to be solved by the invention> There have been various types of molded products, such as packaging containers and lids that cover them, but because they are lightweight, easy to handle, and low in cost, , the container and lid are molded from a synthetic resin sheet.

Among the above molded products such as containers and lids, for example, lids are formed by molding a non-foamed synthetic resin sheet of about 100 to 400 p as shown in FIG. This lid 90 has a convex portion 92 formed near the end of a rising portion 91 by curving the rising portion 91, and a groove 94 between the raised portion 92 and the flat plate portion 93. therefore,
When this lid 90 is placed on the packaging container A, the packaging container A
The side convex mouth edge a engages with the groove 94, and this container A
can be occluded.

By the way, the lid 90 is usually manufactured by molding a non-foamed synthetic resin sheet using male and female molds.

However, when the lid 90 is molded using male and female molds as described above, the groove 94 becomes undercut, making it difficult to release the mold after molding.

Therefore, as the non-foamed synthetic resin sheet for molding the lid 90, a thin sheet that is easily deformable must be used. For this reason, there have been disadvantages in that the strength as a lid is insufficient and the heat retention for the stored items is also low.

In addition, since the lid 90 is molded from a non-foamed synthetic resin sheet, its elasticity is low, and if the size of the opening of the packaging container A is uneven, it will not be possible to pipe the packaging container A. Or, even if the lid 90 could be covered, the sealing performance was poor and if the packaging container A was tilted, the liquid inside the container would leak.

Therefore, this invention was completed as a result of intensive research in view of the above-mentioned technical problems, and it has excellent mold release properties during molding, as well as strength, heat retention, sealing properties, and when covering. The purpose of the present invention is to provide synthetic resin sheet molded products such as containers and lids that have excellent adhesion and a method for molding the same.

Means for Solving the Problems> The gist of the synthetic resin sheet molded products such as containers and lids of the present invention for solving the above technical problems is that the inner periphery of the rising part of the side wall, etc. of molded products such as containers and lids. It consists in forming a protrusion that is more foamed than the other parts of the rising part or the entire circumference, and forming a groove between the protrusion and the flat plate part, and also in the molding method. The gist is that vacuum forming is performed using a mold in which the mold spacing for molding other parts of the rising parts such as the side walls of molded products such as containers and lids is wider than the mold spacing for molding the protrusion molding parts. The protrusion molded part is formed with higher foaming than other parts, and the protrusion molded part, the container,
The object of the present invention is to obtain a molded product having a groove between it and a flat plate part of the molded product such as a lid.

Effect> According to the synthetic resin sheet having the above structure, a protrusion that is foamed more highly than the rising part is provided on part or all of the inner periphery of the rising part of the side wall of a molded product such as a container or a lid. Because the protrusion is highly elastic, when the lid is attached to the container, or when the lid is attached to the container, the groove formed between the protrusion and the flat plate can be Convex parts such as lids and containers can be securely attached.

In addition, according to the method for molding molded products such as containers and lids, the distance between the molds for molding other parts of the rising parts such as the side walls of molded products such as containers and lids is adjusted to mold the protrusion molding part. Since vacuum forming is carried out using a mold having a wider spacing than the mold interval, the protrusion molded portion can rise to a higher degree of foaming than other portions.

Thereby, the elasticity of the protrusion molded portion can be improved, and the molded product can be released easily.

<Examples> The present invention will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 is a perspective view showing an embodiment of the present invention using a lid made of synthetic resin as an example, and FIG. 2 is a sectional view of the lid. Note that FIG. 1 above shows a state in which the lid is turned upside down.

This lid 1 is formed by a flat plate part 11 formed in a size that can cover the mouth of a packaging container, and a side wall part 12 as a rising part formed on the outer periphery of this flat plate part 11. In this embodiment, the flat plate portion 11 is approximately rectangular. Further, as shown in the figure, the flat plate portion 11 is shown including a portion continuous from the flat plate portion to the side wall portion 12.

Among the side wall portions 12, a side wall portion 12a on the long side.

On the inner periphery of 12a, there is a protrusion 13 that protrudes in opposite directions.
is provided near the end. This protrusion 13 is formed to be more foamed than other parts of the side wall 12. A groove 14 is provided between the protrusion 13 and the flat plate portion 11. Due to this? J14 can be engaged with the mouth edge a of the packaging container A, as shown in FIG.

Note that the flat plate portion 11 has an upwardly stepped portion on its outer circumferential band, and has increased strength against bending deformation. In this example, the protrusion 13 is formed by the long side wall portions 12a,
12B, both side walls 12b, 12 on the short side
b, or the entire inner periphery of the side wall portion 12.

As shown in FIG. 3, Ml is entirely formed of a laminated sheet S in which non-foamed thermoplastic synthetic resin films F are adhered to both surfaces of a foamed resin sheet S'. As the foamed resin sheet S', a foamed polypropylene resin sheet with a low expansion ratio is used. Foamed polypropylene resins have polypropylene as a main component, but also include those containing thermoplastic resins or inorganic fillers that are miscible with polypropylene. Examples of the thermoplastic resin include heat-resistant polystyrene and polymethyl methacrylate. Examples of inorganic fillers include talc, titanium dioxide, clay silica, and alumina.

In addition, the foaming ratio of the foamed polypropylene resin sheet is
5.5 times or less is used. If the foaming ratio is 5.5 times or more, a wave striped pattern will occur due to extrusion molding.
This is because variations in elongation occur during thermoforming, resulting in uneven thickness and cracks in the molded product. In this respect, particularly preferable results can be obtained with foams having an expansion ratio of 2.5 times or less.

Further, the non-foamed thermoplastic synthetic resin film is made of polyethylene, polypropylene, polymethylpentene, polyethylene terephthalate, polybutylene terephthalate, etc. and has a thickness of 25 Ita or more and 1000 μm or less. , are laminated on both sides of the foamed polypropylene resin sheet by thermal adhesion or the like.

This thermoplastic synthetic resin film is particularly suitable for 40 to 8
Preferably, the thickness is 0 μm. In addition, when this film is molded using the lid molding method described below, it prevents gas from escaping from within the foamed polypropylene resin sheet and ensures that it can be formed to the desired foaming ratio. It also improves printing properties and surface slippage, and prevents the appearance of stone grain patterns on foam sheets. Therefore, in cases where a desired expansion ratio can be achieved using only a low-foam resin sheet, the resin film can be omitted.

Next, a method of forming the lid 1 will be explained with reference to FIG. 4 (ω).

The mold 2 used for this molding is capable of vacuum forming the heat-softened laminated sheet S from both sides, and consists of a male mold 21 and a female mold 22, and both molds can be vacuum depressurized. pores 21a.

22a is formed. The pores 21a and 22a are
The hole diameter is approximately 0.6 mm, and the degree of vacuum is 500.
Connected to a vacuum suction device with a capacity of 11 g or more.

Although the distance between the male die 21 and the female die 22 is made wider than the thickness of the laminated sheet S after being heated and softened, the gap between the male die 21 and the female die 22 is particularly large, especially in the die portions 21b and 22b for forming the protrusion 13 of the lid 1.
The interval is set wider than the interval between the other mold parts for molding the flat plate part 11 and the side wall part 12. However, it is preferable that the interval between the molds is set to at most 2.5 times or less the thickness of the laminated sheet S after being heated and softened. This is because if it exceeds 2.5 times, the magnification of the foam layer increases and the bending strength decreases extremely.

In this example, the temperature of the mold 2 is as follows:
Since it is made of a polypropylene resin with a large specific heat, it is preferable to set the temperature to 50° C. or lower in consideration of cooling. However, if the temperature of the mold is too low, the laminated sheet S that has been softened by heating must be cooled, making it impossible to perform sufficient vacuum forming. Therefore, the temperature of the mold is preferably in the range of about 35 to 45°C.

When manufacturing the lid 1, first, before inserting a laminated sheet S (see Fig. 3) made of a foamed polypropylene sheet S' on which a polypropylene film F is laminated on both sides into the mold 2, the heater temperature is set to 300°C. The material is heated with a far infrared heater (not shown) for about 45 to 60 seconds to soften it. Then, this laminated sheet S is inserted between the male and female molds 21 and 22 (see Fig. 4 (ω)). Then, the female mold 22 is applied to the lamination rate S, and the pressure is reduced to perform vacuum forming with the female mold 22. (See Fig. 4<b+).Next, after matching the outer peripheral parts 21C and 22c of the male and female molds 21 and 22 (see Fig. 4(C)), the male mold 21 is depressurized to cause free foaming inside the mold. Obtaining the lid 1 as a molded product (see figure 4) Kotoki mold 2
The temperature of is maintained at 50°C or less, preferably 40°C. As a result, the laminated sheet S is foamed, and the flat plate part 11, side wall part 12, protrusion part 13, and groove 14 are formed into a predetermined shape, and the lid 1
is manufactured. Then, the inside of the mold 2 is returned to normal pressure, the mold is opened, and the lid 1 is taken out.

In addition, when molding a laminated sheet with a thickness of 1 mm at a foaming ratio of 2 times, the second interval of the mold is set such that the interval between the parts 21b where the protrusions 13 are formed is 2.5 times, the flat plate part 11 and the side wall. If the interval between the parts where the parts 12 are molded is set to 2 mIB, the protrusion 13 part will be more foamed than other parts due to free foaming in the mold.

That is, the expansion ratio of the protrusion 13 is 5 times, and the expansion ratio of the other parts is 4 times.
Formed twice.

In the above molding process, while protruding the laminated sheet S using the male mold 21, the outer peripheral portion 21C122c of the mold 2 may be matched, and then both molds 21 and 22 may be depressurized.
Alternatively, after first performing vacuum molding with the male die 21, the outer peripheral portions 21C and 22c of the mold 2 may be matched, and then vacuum molding may be performed with the ζ female die 22.

As described above, the lid of this embodiment is formed from a laminated sheet in which thermoplastic synthetic resin films are laminated on both sides of a foamed polypropylene resin sheet.
When used as a lid for a packaging container, it has sufficient thickness and strength, and also has excellent heat retention and heat resistance. Further, the groove 14 of the lid 1 is located at the convex mouth edge a of the packaging container A.
Since it can be engaged with the container, it has excellent adhesion and can reliably seal the liquid inside the container. Furthermore, since the protrusion 13 of the lid 1 is foamed at a higher rate than other parts, it has excellent elasticity, and even if there are variations in the size of the container opening to be covered, it will prevent the lid from being improperly attached. , there is less risk of liquid leakage, etc.

Furthermore, even during molding, since the protrusion 13 of the lid 1 has good elasticity, the mold release is performed smoothly, so that workability is improved.

Note that as another example of the foamed synthetic resin sheet, a foamed polystyrene sheet or a laminate thereof can also be used.

In addition, in the above embodiments, the lid of a packaging container was shown as an example of the molded product, but this molded product may also be a packaging container, and is not limited to the container or lid described above, but may also be a flat plate part. Any molded product that has a rising portion, a protrusion on the inner periphery of the rising portion, and a groove between the protrusion and the flat plate portion can be applied to various products.

(Concrete example) Next, a specific example of this lid 1 will be explained.

First, a foamed polypropylene sheet with a foaming ratio of 2 times and a thickness of 1059 μm was made with a thickness of 49 μm on the outside and 5 μm on the inside.
Glue 3 μl of polypropylene film with adhesive,
A laminated sheet S having a thickness of 11111 μm and a total basis weight of 801 g/rrr was formed. And heater temperature 300
The laminated sheet S was softened by heating for 58 seconds with a far infrared heater at .degree. Thereafter, the distance between the molds forming the flat plate portion 11 was set to about 1.5 mm, the distance between the molds forming the side wall portion 12 was set to about 1.0 mm, and the distance between the molds forming the protrusion 13 was set to about 2 mm. Both sides were vacuum formed using a Matuchimold mold set to .5 mm. At this time, keep the mold at 40℃ and -
Molding was performed under reduced pressure of 550 mwHg.

As shown in FIG.
2) ■, 0 dragon, thickness of protrusion 13 (tl) 2.5 am
Met.

<Effects of the Invention> As described above, according to the synthetic resin sheet molded products such as containers and lids of the present invention, since they are formed from foamed sheets, they have excellent strength and heat retention properties, and are highly foamed. Since it is equipped with a protrusion, it has better elasticity and tighter fitting.It also makes it easier to release the mold during molding, improving productivity and improving the fit. It also becomes easier to put on and take off by utilizing the elasticity of the product.

Furthermore, according to this molding method, the protrusions at the rising part of the molded product are molded with different mold spacings at other parts of the rising part, so that the protrusions are highly foamed and molded.
A portion having high elasticity can be easily formed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a synthetic resin lid as a molded product according to an embodiment of the present invention, FIG. 2 is a sectional view of the lid, and FIG. 3 is a sectional view of a laminated sheet constituting the lid. Figures 4 are (a) to (small) are cross-sectional views showing the steps of manufacturing the above-mentioned lids, Figure 5 is a cross-sectional view showing the dimensions of a specific example lid, and Figure 6 is a conventional lid as a molded product. 1... Lid, 12... Side wall part, 14... Groove, 2... Mold, 21b. 11... Flat plate part, 13... Projection part, b.・Protrusion molded part.

Claims (1)

[Scope of Claims] 1. In a molded product such as a container or a lid made of a foamed resin sheet or a synthetic resin sheet laminated with a non-foamed resin film, the inner periphery of the rising part of the side wall, etc. of the molded product such as the container or lid. Synthetic resin for containers, lids, etc., characterized by forming a protrusion that is more foamed than other parts of the rising part or the entire circumference, and forming a groove between the protrusion and the flat plate part. Sheet molded product. 2. In the method of molding molded products such as containers and lids using foamed resin sheets or synthetic resin sheets laminated with non-foamed resin films, other parts of the rising parts such as side walls of molded products such as containers and lids. Vacuum forming is performed using one mold with a mold interval wider than the mold interval for molding, and the protrusion molded part rises and is foamed more highly than other parts, and the protrusion molded part and the molded product flat plate such as a container or lid A method for molding synthetic resin sheet molded products such as containers and lids, characterized by obtaining a molded product having a groove between the container and the lid.