JPH0237861B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic laminated tube that can be used as a body member of a can for storing food and drink, as a container material that does not cause any food hygiene problems.

It goes without saying that containers for food and beverages must be safe from a food hygiene perspective, but they also need to have gas barrier properties, retort sterilization, water resistance, oil resistance, self-supporting properties, etc., depending on the purpose. It is required to have various physical properties. and,
For example, metal cans have these physical properties, but
Recently, the problem of empty can pollution has been brought up.
Another problem was the poor transportation efficiency of sending cans with large empty volumes from can manufacturing plants to filling factories. In addition, paper containers have recently been used, but they have gas barrier properties, heat resistance, water resistance,
Various treatments were required to impart oil resistance and the like, and there was also the problem of transportation efficiency mentioned above.

On the other hand, plastic film has the advantage of being easy to mass produce, easy to process, and can be easily imparted with various physical properties, but it is necessary to laminate various plastics to create a container wall material with the desired physical properties. be. If the laminated film is spirally wound to form a cylinder, adhesives, etc., which are undesirable from a food hygiene perspective, will come into contact with the contents at the cross section of the laminated film, so it cannot be used as a food or drink content. It becomes inappropriate.

The inventors of the present invention conducted various studies to develop a plastic laminated tube that could be used for food and drink containers.The inventors decided to make the innermost surface of the laminated film a material that does not pose a food hygiene problem, and to wrap the film in a spiral shape to form a tube. When forming the film, if the lower part of the overlapping side edges is folded upwards and the folded part is glued to the overlapping film, a tube that does not cause food hygiene problems can be obtained. It has been found that by further laminating a film on top of the can body, it is possible to obtain a body member of a can that is highly practical in terms of strength and aesthetics. The inventors discovered that this technique can be applied to various fields other than food and drink, and based on this finding, they completed the present invention.

That is, the present invention provides a laminated tube in which the side edges of the laminated film are overlapped and wound spirally, and the overlapping portion is bonded to form a cylindrical shape, in which the side edge of the laminated film on the lower side of the overlap A plastic laminated tube characterized in that the folded portion is folded upward, the folded portion is bonded to the overlapping portion of the laminated film on the upper side of the polymerization, and a film is further laminated on the outer surface of the tube. It is something.

The innermost layer of the laminated film is made of a material that does not affect the contents in relation to its intended use. For example, if the content is a food or drink, a polyolefin layer such as a polyethylene layer, a polypropylene layer, or an ethylene-propylene copolymer layer is provided as the innermost layer. When the contents are treated under high temperature and pressure such as retort sterilization, low density polyethylene has insufficient heat resistance, so it is necessary to use high density polyethylene.

Each layer other than the innermost layer may be laminated in an appropriate combination depending on the desired physical properties; for example, if it is necessary to provide gas barrier properties, an aluminum foil or a resin layer with gas barrier properties may be provided. . Needless to say, if the adhesion between the layers is insufficient, an adhesive layer may be provided between the layers.

The thickness of the laminated film is not particularly limited, but it is usually 250μ or less, and from the viewpoint of workability and cosmetic properties, etc.
Approximately 50 to 150μ is suitable.

A cross section of an example of the laminated film 1 is shown in FIG.
This film 1 is for food use, and has an unstretched polypropylene layer A as the innermost layer, and a carboxylic acid grafted polypropylene layer B as an adhesive layer on top of the unstretched polypropylene layer A.
This is followed by an aluminum foil C, a urethane adhesive layer D, and a polyester layer as the top layer. The thickness of each layer is approximately
70μ, others are about 5 to 15μ, overall 100μ
Before and after.

The present invention is characterized in that one side edge of such a laminated film is bonded in a folded state. The folded side edge is the lower one of the overlapping side edges. The folding width depends on the pipe diameter, adhesive strength, required airtightness, etc., but is usually 2 to 20 mm.
It is about mm. A cross section in the pipe length direction is shown in Figure 2.
In principle, the ends 2 of the side edges are aligned as shown in this figure, but the invention is not limited to this. For example, as shown in FIG. The portion 4 may be glued to the outer surface of the lower film. It goes without saying that even if this is not the case, the side edge portions 2 may be deviated due to a mere problem of processing accuracy.

The film laminated on the outer surface of the cylinder is for imparting rigidity and cosmetic appearance, and the material is preferably polyethylene, polypropylene, etc., and polypropylene is particularly suitable. The thickness of the laminated tube of the present invention formed by adhering this film is about 300 to 2000μ,
Particularly preferred is about 700 to 1000μ.

In the laminated tube of the present invention, for example, a tube 5 is formed by attaching a folding device on the side edges of the paper sheet in a known device for forming a paper tube by spirally winding a paper sheet, and a film is further laminated on the outer surface of the tube. It can be manufactured simply by The folding device does not need to have a complicated mechanism; for example, as shown in FIG. 4, just before winding the running web 6 around a mandrel 7, a rod 8 may be provided upright or slightly inclined. 2
Reference numeral 6 denotes a positioning member that restricts one end of the traveling web 6. If necessary, a pinch roller (not shown) or the like may be provided between the mandrel 7 and the rod 8. In order to easily remove the tube 5 from the mandrel 7, a raw fabric 6 is placed on the mandrel 7.
Before wrapping the material, it is preferable to wrap a sliding paper coated with paraffin in advance in a spiral shape. On the other hand, if slipping paper or the like is not used, the mandrel 7 may be coated with Teflon, fluorine resin, etc.
Alternatively, it is necessary to process it with ceramic.

An adhesive may be used to bond the overlapping portion 9, but in the present invention, since the contacting surfaces are made of the same material, bonding can be achieved simply by heating. Although not shown in the example of FIG. 4,
By installing burners etc. at two locations 10 and 11 to heat both side edges of the film and partially melting the heated side surfaces of both sides, when both sides overlap, the tensile force of the original film is used. They are pressed together and welded.
In this case, if the pressure is insufficient, a pressure roll may be used.

The outer surface 12 of the tube 5 thus formed is further wound or covered with other plastic film, paper, or the like. Such examples are shown in FIGS. 5-7. In the example shown in FIG. 5, after the left side edge 13 of the original fabric 6 is folded back, the left side edge 13 is heated from below and the right side edge 14 is heated from above using frame sealers 15 and 16, so that the heated surfaces of each side edge are partially heated. The polymer is melted and wrapped around a Teflon-coated mandrel 7 to weld the overlapping portion. Next, 200 μm unstretched polypropylene films 17 and 18 are both coated with urethane adhesive on their lower surfaces by a roller 19.
20, passed through dryers 21 and 22, and then wound around a mandrel 7 to cover and strengthen the laminated tube. The example shown in Figure 6 is an example in which the middle layer film is applied by deflation extrusion using a round die 23, and the upper layer film 24 is wrapped with polyethylene terephthalate coated with a urethane adhesive on its lower surface. It is covered. The example shown in FIG. 7 is an example in which the sheet is extruded using a T-die 25 and rolled and adhered in a molten state. In both FIGS. 6 and 7, the left part is omitted, but this left part is the same as the left part of the xy section in FIG. In addition, in the method shown in FIGS. 5 to 7, the winding of the film indicated by 17 may not be necessary depending on the material of the film.

The tube of the present invention is typically used in the body of a can. In that case, the same laminated film used for the laminated tube may be used for the top and bottom lids, but if necessary, the laminated film 1 may have adhesive properties and be used for the purpose of the contents. It is also possible to use a new lid whose inner surface is made of a material that does not affect the relationship between the two by injection molding or the like. End cross-sections of some examples of lid portions are shown in FIG.

The laminated tube of the present invention has a simple structure, can be manufactured by simple means, and is suitable for use as a body member for packaging containers, especially cans, whose materials are limited in relation to the contents. Although the use of the tube of the present invention is not particularly limited, it is particularly suitable for cases where the contents strictly limit the material of the container, and such uses include various foods and drinks, medicines, etc.

[Brief explanation of drawings]

FIG. 1 shows a cross section of an example of a laminated film that is a tube material of the present invention. FIG. 2 shows a part of a cross section in the longitudinal direction of a cylindrical part of a pipe according to an embodiment of the present invention, and FIG. 3 shows a part of a cross section in the longitudinal direction of a cylindrical part according to another embodiment. It shows the part. FIG. 4 is a perspective view showing a state in which a tube is formed by winding a laminated film around a mandrel, and FIGS. 5 to 7 show a state in which a film is further applied to the formed tube. . Although the left portions of FIGS. 6 and 7 are omitted, these portions are the same as the left portions of section xy in FIG. 5. FIG. 8 shows cross sections of three examples of can lid attachment parts when a can body is formed using the laminated tube of the present invention. 1... Laminated film, 2, 4... End of side edge, 3...
Side edge, 5...tube, 6...raw fabric, 7...mandrel, 8...
Rod, 9... Polymerization part, 10, 11... Burner, 12...
Outer surface of cylinder, 13...left edge, 14...right edge, 15,
16... Frame sealer, 17, 18... Film, 19, 20... Roller, 21, 22... Dryer, 23... Round die, 24... Film, 25... T
Dice, 26...positioning member.

Claims (1)

[Scope of Claims] 1. In a laminated tube in which the side edges of laminated films are overlapped and wound spirally, and the overlapping portions are bonded to form a cylindrical shape, the laminated film on the lower side of the overlap A plastic laminate characterized in that the side edge portion is folded upward, the folded portion and the overlapping portion of the laminated film on the upper side of the polymerization are adhered, and a film is further laminated on the outer surface of the cylinder. tube. 2. The plastic laminated tube according to claim 1, wherein the film laminated on the outer surface of the tube is extruded from a die.