JPH0429531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a see-through tube for a rigid transparent container.

Transparent rigid cylindrical containers are widely used as packaging containers for dry foods, clothing, and the like. This container is generally obtained by making a see-through tube, cutting the see-through tube to a predetermined length, and attaching lids to the top and bottom. Conventionally, when manufacturing a see-through tube for this type of container, hard transparent resin was used. The problem was that the sheets were flat-rolled and the overlapping seams were glued or high-frequency welded, resulting in very poor productivity.

As a countermeasure to this problem, there is a method, as disclosed in Japanese Patent Application Laid-open No. 77557/1983, in which a hard resin band is wound in a spiral shape so that the edges overlap, and the overlapping edges are bonded or welded. This method improves productivity. However, the stepped part of the seam protrudes spirally on the outer periphery of the see-through tube, which is unsightly and has the disadvantage of detracting from the aesthetic appearance, which is important for product packaging. When used, the refractive index of light changes at the overlapping part of the seam step, which causes fatal defects as a see-through container, such as the contents appearing distorted or small when used as a container. Moreover, when the lids are attached to the upper and lower ends after cutting to size, a gap is created by the stepped portion of the joint protruding from the outer peripheral surface, resulting in poor sealing performance.

The present invention was developed through research to eliminate the above-mentioned conventional drawbacks, and its purpose is to efficiently obtain a see-through tube for a transparent container that has a good appearance and good sealing performance. The purpose of this invention is to provide a new method for manufacturing see-through tubes.

In order to achieve the above object, the present invention is a multi-layer transparent film in which a plurality of transparent resin films are pasted together in advance with a phase shift in the width direction so that steps of equal width and opposite directions are formed along both side edges. Using a resin band,
This multilayer transparent resin band is spirally wound so that the stepped portions are polymerized, and the stepped portions are joined to form a continuous see-through tube without stepped joints on the outer periphery.

The present invention will be explained below based on the accompanying drawings.

Figures 1 to 3 show an embodiment of the method for manufacturing a see-through tube for a rigid transparent container according to the present invention. A multilayer transparent resin band 2 with a predetermined thickness t is formed by pasting a thin transparent resin film on the front.
make.

The multilayer transparent resin band 2 has a thickness of about 1/2 in Fig. 2a.
Two transparent resin films 1, 1 of 2t are laminated together, and as shown in FIG. 1 and 1 may be bonded together. In either case, the transparent resin films 1, 1 are laminated together with the phase shifted in the width direction so that stepped portions 3, 3' of equal width and opposite directions are formed along both side edges. ing. The stepped portions 3, 3' have a thickness approximately half that of the multilayer transparent resin band 2.

The above bonding may be carried out by any method such as the so-called co-extrusion method, but in this embodiment, as shown in FIG. Adhesive resin 7 is applied to the inner surface of at least one of the transparent resin films 1 in front of the pressure roll 5 using an applicator 6, leaving a margin 11 on the side edge, and then the pressure roll 5 is used to apply adhesive resin 7 to the inner surface of at least one of the transparent resin films 1. 1 is compressed to form a continuous multilayer transparent resin band 2.

Next, in the present invention, the multilayer transparent resin band 2 obtained in the previous step is spirally wound around a mandrel 8 as shown in FIG. At this time, as shown in Fig. 3a, an angle is set so that the stepped portions 3 and 3' formed on the multilayer transparent resin band 2 overlap each turn,
Then, as the spiral is wound, the surfaces of the overlapping stepped portions 3 and 3' are joined. 14 is a joint.

This joining method may be bonding using an adhesive or welding using a high frequency welder 9 as shown in the figure. When using the former adhesive method, the stepped portion 3 or 3' is attached just before winding the spiral.
If you use the latter welding method, use a high frequency welder 9 at a position of one turn or more.
etc., and apply high frequency to the overlapping portion of the stepped portions 3 and 3'.

As a result, the see-through tube 10 is gradually formed along the axial direction of the mandrel 8, but in the case of the present invention, the stepped portions 3 and 3' having a thickness of 1/2 of the thickness of the tube are helically overlapped. Because of this, it has a smooth tubular or cylindrical shape with no seam protrusions on the inner and outer surfaces.

In addition, instead of the above method, the present inventor also tried a method of cutting edges in the opposite direction on both sides of a single-layer transparent resin sheet, but this method resulted in the edges becoming cloudy, so the spiral shape was not formed when the pipe was manufactured. There was a problem that an opaque zone was formed and the transparency was reduced.Also, we tried laminating two transparent resin films by spirally winding them around a mandrel instead of laminating a transparent resin film in advance, but Since the transparent resin film could not be stretched, bubbles were generated due to uneven adhesion, which made it unsuitable. However, in the present invention, since the transparent resin films 1, 1 are bonded together in a planar state in advance, tension can be applied, so that bubbles are not generated and good transparency can be ensured.

The see-through tube 10 obtained as described above is cut into necessary dimensions when removed from the mandrel 8, thereby forming a container body 12 as shown in FIG. 6. A cylindrical hard transparent container is obtained by attaching lids 13 and 13' to the top and bottom of this container body 12 by caulking or welding. As there is no seam step on the outer surface of the container main body 12, the appearance is good, and since the outer circumferential surfaces of the upper and lower ends are straight, the lids 13, 13' can be attached tightly, and the sealing performance is good. becomes. Furthermore, since it has a multilayer structure made by laminating two or more transparent resin films 1, 1, it has higher mechanical strength than those made of a single layer sheet, and since there are no stepped seams on the inner surface, it can be easily used with lining tapes. Reinforcement can be easily performed and the container can have high strength as a whole.

Next, specific examples of the present invention will be shown.

Example Two polyvinyl chloride films with a width of 110 mm and a thickness of 0.2 mm were laminated together by the method shown in Fig. 1 so that each side edge had an opposite step of 7 mm, and the thickness was 0.4 mm. A multilayer transparent resin strip with a width of 110 mm was made. A solvent-based urethane adhesive was used as the adhesive. The multilayer transparent resin band exhibited good transparency over its entire width and was free of bubbles.

Next, the multilayer transparent resin band was spirally wound around a mandrel with a diameter of 73 mm, and the stepped overlapping portions were welded. Separately, the polymerized portion was bonded with a solvent-based urethane adhesive while spirally winding it around a mandrel. As a result, both are 20m/
A transparent rigid see-through tube with a diameter of φ73 mm was manufactured at min. See-through tubes are smooth with no joint protrusions on the inner and outer surfaces, and the spiral joint has good transparency.
The welding and bonding conditions were also strong. This see-through tube was cut to 155 mm, a metal lid was caulked on, and granular food was stored there, but there was no leakage at all.
It also showed strong resistance to compression in the radial and axial directions.

I tried manufacturing see-through tubes of the same size using a conventional manufacturing method, but could only produce about 6 tubes per minute. According to the method of the present invention, productivity has been significantly improved to over 60 pieces per minute.

According to the present invention as described above, in order to obtain a see-through tube for a transparent rigid container, step portions 3 and 3' having the same width and opposite directions are formed in advance on a plurality of transparent resin films 1 and 1 along both side edges. Using a multilayer transparent resin band 2 that is pasted together with a phase shift in the width direction so as to Since we decided to join the parts,
There are no seams between the outer and inner peripheries, and the product has good appearance and transparency so that the contents are not distorted and visible. Also, there is no gap between the inner periphery of the lid and excellent sealing performance. A see-through container can be obtained. Also,
Instead of using a single-layer resin strip with edges, a plurality of transparent resin films 1, 1 are used as the material, and are phased in the width direction so that step portions 3, 3' of equal width and opposite directions are formed along both side edges. Since the multi-layer transparent resin strip 2 is used, which is laminated in a staggered manner, it has excellent mechanical strength in the radial and axial directions, maintains good transparency, and can freely create see-through tubes with the desired thickness. An excellent effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the manufacturing steps of a multilayer transparent resin band in the see-through tube manufacturing method of the present invention, and FIG.
Figures a and b are enlarged cross-sectional views showing embodiments of the multilayer transparent resin band according to the present invention, Figure 3 is a plan view showing the pipe manufacturing step of the present invention, Figure 3a is a partial cross-sectional view thereof, and Figure 4 is a A cross-sectional view of a see-through tube according to the present invention, FIGS. 5a and 5b are also partial cross-sectional views thereof,
FIG. 6 is an exploded perspective view of a rigid transparent container obtained using the see-through tube of the present invention. 1, 1...Transparent resin film, 2...Multilayer transparent resin band, 3,3'...Stepped portion.

Claims (1)

[Claims] 1. In order to obtain a see-through tube for a transparent rigid container, a plurality of transparent resin films 1, 1 are preliminarily cut in the width direction so that stepped portions 3, 3' of equal width and opposite directions are formed along both side edges. It is characterized by using a multilayer transparent resin band 2 bonded together with a phase shift, and winding this multilayer transparent resin band 2 in a spiral shape so that the step portions 3 and 3' are polymerized, and joining the polymerized step portions. A method for manufacturing see-through tubes for transparent rigid containers.