JPH0126329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tube container body, and more particularly, to a tube container body in which the surface of a multilayer cylindrical body including a metal layer is coated with a continuous thermoplastic resin. This is a manufacturing method.

Conventionally, tube containers formed only of synthetic resin layers have soft and beautiful surface properties, but on the other hand, they have significantly lower problems than metal containers.
In order to insert a metal layer into the tube container body, since the molding conditions for synthetic resin and metal are significantly different, generally a metal foil adjusted to a thickness of 3 to 100μ is prepared in advance, and a film containing this metal foil is prepared. create and
This multilayer film was rolled into a cylindrical shape and the overlapped ends of the film were sealed to form a cylindrical body, and this cylindrical body was used as a main body with a mouth formed at one end to form a tube container. However, this tube container with a metal layer generally has low pressure resistance, and the overlapping portion of the tube body is easily damaged.
Since the overlapping parts are easily damaged during filling, storage, and extrusion of the contents, there was a problem that the contents leaked. Furthermore, since the sealed parts are overlapped, there is a problem in that if excessive pressure is applied during sealing to eliminate the level difference on the surface, cracks may occur in the metal layer. Also, when sealing the bottom, unless sufficient pressure is applied, the area near the overlapping portion cannot be completely sealed, so unreasonable pressure is likely to be applied. There are problems such as cracks in the metal layer. Furthermore, as mentioned above, the difference in level between the overlapping parts of the tube body is large, so during secondary processing such as surface printing or foil stamping, if letters or designs are applied to the difference in level, the image will not be printed and will be cut off. As a tube container, it lacked the luxury feel.

To solve the above problems, we created a thin film containing a metal layer, rolled it up and sealed the ends to create a cylindrical body, and then coated the outside of this cylindrical body with synthetic resin. A tube container using a tube body coated with the material has a smooth surface, and good strength and effectiveness can be obtained without applying excessive pressure for sealing, printing, foil stamping, etc. The manufacturing method for such tube containers is as follows:
As described in No. 332, it is being considered to directly apply the technology of coating the outside of metal tubes with resin and the technology of covering electric wires. These molding methods are effective for forming thick coatings on rigid objects that are difficult to deform under external pressure, such as metal tubes and electric wires, due to in-die adhesion, but flexibility is required, which is the object of the present invention. If the material is soft, such as the body of a tube container, it will deform and the coating thickness will vary significantly depending on the location, making it difficult to coat it uniformly with the thickness of a normal tube container body, which is 0.3 to 0.6 mm. It was hot.

The present invention solves the problems in view of the above points, and provides a method for manufacturing a tube container body having a thin, uniform coating layer and a seamless surface. That is, by preparing a film in which at least an adhesive resin layer, a metal layer, and an adhesive resin layer are laminated in this order, the ends of this laminated film are fused to form a cylinder, and the tip of this cylindrical film is taken off. A continuous cylindrical film is made, the cylindrical film is passed through a die head, the molten parison extruded from the tip of the die head is coated on the outer surface of the cylindrical film outside the die head, and This method of manufacturing a tube container body is characterized in that the inner surface of a coated cylindrical film is cooled by a cooling mandrel.

By means of an apparatus according to an embodiment shown in the drawings below,
The manufacturing method of the present invention will be explained in detail.

As shown in FIG. 1, first, a film 1 in which at least an adhesive resin layer, a metal layer, and an adhesive resin layer are laminated in this order is rolled up using a mandrel pipe 2 and a film guide 3, and then laminated by a sealing machine 4. The ends of the film are fused to each other to form a cylinder, and when this cylindrical film 5 is taken off, it is successively rolled up by a guide to obtain a continuous cylindrical film 5. A cooling pipe 6 is provided at the tip of the mandrel pipe 2, and a cooling mandrel 7 is continuously provided at the tip of the cooling tube 6. Further, a die head 9 connected to an extruder 8 is provided around the cooling pipe 6, and a space with a sufficiently large diameter is provided so that the die head 9 and the cylindrical film 5 do not come into contact with each other when the cylindrical film 5 passes through. 10 are provided. Therefore, the present invention involves continuously passing the cylindrical film 5 obtained as described above into the space 10 of the die head 9, and covering the cylindrical film 5 with the molten parison 11 extruded from the die head 9. A coated cylindrical film 12 is formed, and the coated cylindrical film 12 is cooled by a cooling mandrel 7 to obtain a seamless tube that becomes the tube container body. To make a tube container, the coated cylindrical film 12 is cut to a desired length to form a tube container body, and a mouth portion is formed at one end of the tube container body by a conventional method to obtain a tube container.

As the laminated film 1, a film in which at least an adhesive resin layer, a metal layer, and an adhesive resin layer are laminated in this order is used, and the metal layer has high extensibility like aluminum and has few pinholes. A metal foil with a thickness of 100μ, preferably 7 to 30μ is good. In addition, as an adhesive resin layer for such a metal layer, a combination of an adhesive such as polyvinyl acetate resin, polyurethane resin, or polyester resin and a resin such as polyethylene, ethylene methyl acrylate (EMA), ethylene acrylic resin, etc. A combination of using a polyolefin resin with an unsaturated carboxylic acid or a derivative thereof such as an acid copolymer resin (EAA) to bond the metal layer is also possible. These adhesive resin layers have fusion properties when rolling the laminated film 1 together and fusing the ends of the film, fusion properties with the mouth resin when making a tube container, and fusion properties with the coating layer. Any resin may be used as long as it has excellent fusion properties between adhesive resin layers when sealing the bottom of a tube container, and may have a single-layer structure or a multi-layer structure using a combination of different resins. The outer adhesive resin layer may be made of a different resin.

Various methods are available for producing this laminated film, including extrusion lamination using a T-die method and dry lamination using a laminator.

A cylindrical film is created by wrapping the laminated film 1 as described above around the mandrel pipe 2 and fusing the ends together. However, it is better to bend the film into a cylindrical shape and wrap it around the mandrel pipe 2 because the device for fusing the ends of the film together, that is, the sealing machine 4, is simpler, so in this embodiment, the method of winding the film into a cylindrical shape is used. For the fusion in the sealing machine 4, high frequency fusion methods such as heat fusion and ultrasonic fusion can be considered.

Next, the cooling pipe 6 in the apparatus used in the present invention is for passing a medium such as water or oil for cooling the cooling mandrel pipe 7, and has a structure that does not contact the cylindrical film 5. This is because when the cylindrical film 5 comes into contact with the cooling pipe 6, the temperature of the cylindrical film 5 decreases and the fusion force between the molten parison 11 and the cylindrical film 5 decreases. There is frictional resistance between the cylindrical film 5 and the cylindrical film 5, and it is necessary to apply strong tension to pull the cylindrical film 5. This makes it easy for cracks to enter the metal layer within the cylindrical film 5, resulting in deformation of the cross-sectional shape and the need to remove the cylindrical film 5. To prevent problems such as not being able to obtain a tube container body with a uniform shape and thickness, the cooling tube 6 is made sufficiently thinner than the cylindrical film 5, that is, the mandrel pipe 2 and the cooling mandrel 7, and is in contact with the cylindrical film 5. They should be provided with enough space to prevent any damage. This cooling pipe 6 serves as an inflow and an outflow path for the cooling medium for the cooling mandrel 7, and two cooling pipes may be used, or as shown in Fig. 2, a double pipe is used with the inside as the inflow path. , the outside may be used for the outflow path. In addition, dew condensation may occur on the surface of the cooling pipe 6, and the dew may fall on the inner surface of the cylindrical film 5, causing a local temperature drop and reducing the adhesive strength. Preferably, a heat insulating layer is provided.

Next, the cooling mandrel 7 provided at the tip of the cooling pipe is placed on the outside of the cylindrical film 5 to melt the parison 1.
1 cools the coated cylindrical film 12. The fused surface at the end of the film is softened by the radiant heat from the die head 9 and the conductive heat from the melted parison, making it easy to separate. Since the cross-sectional shape is easy to change, the covering cylindrical film 12 is rapidly cooled to prevent a rise in temperature of the end fused surface, and to set the desired cross-sectional shape, for example, circular, and cool and solidify it. . In other words, there is a risk that the shape will change if only rapid cooling is performed, such as by directly pouring water on it, and in order to prevent the temperature from rising inside, especially at the fused surface at the end of the cylindrical film 5,
Cooling through the coating layer is not effective. In addition, if a liquid such as water is applied directly, the splashed liquid will fly onto the surface of the molten parison 11 and cause some parts to become dented, impairing the smoothness of the surface and significantly lowering the product value. In secondary processing such as foil stamping, such a decrease in surface smoothness may cause patterns, letters, etc. to be chipped. However, as in the manufacturing method of the present invention, after the coating layer is cooled using the cooling mandrel 7 and solidified, it is possible to bring a cooling medium such as water into contact with it from the outside to further cool the coating layer sufficiently.
In addition, in consideration of shrinkage when the molten parison 11 is coated on the cylindrical film 5, the cooling mandrel 7 is made slightly thinner than the mandrel pipe.
By providing a taper of ~2/100, shielding damage can be eliminated by increasing the frictional force between the cooling mandrel and the cylindrical film due to contraction.
Further, it is easier to mold the surface of the cooling mandrel 7 if it has a uniform roughness of about 0.1 to 1 μm.

Next, a so-called cross die head type die head 9 is used to extrude the molten parison 11, and the die head 9 can be used for single layer extrusion or multilayer extrusion. At the center of this die head 9, a cavity 10 is provided which has a sufficient diameter so that the cylindrical film 5 passes through the interior thereof and does not come into contact with the cylindrical film.The center of this cavity 10 and the center of the cylindrical film 5 are It needs to almost match. Therefore, the cooling mandrel 7
If a roll 13, a cylindrical tube, etc. are provided on the outside of the coating layer 5, and the coated cylindrical film 5 is supported by the roll 13 from outside the coating layer when it is cooled, the position of the roll 13, etc. can be moved. By adjusting the position of the cooling mandrel 7, the thickness of the resin to be coated can be adjusted with higher precision.

Next, the extrusion speed of the molten parison 11 extruded from the die head 9 connected to the extruder 8 is made slower than the speed at which the molten parison 11 is passed through the cylindrical film 5, so that the molten parison 11 is pulled down and transferred to the cylindrical film 5. Since it is coated, the coating layer can be applied uniformly. At this time, by degassing the space 10 in the die head 9 by surrounding it with a sealing material 15 as shown in FIG. 2, the molten parison 11 is brought into contact with the cooling mandrel 7 while still at a sufficiently high temperature. ,
Adhesive strength can be increased. Especially when making a thin parison 11 (0.1 to 0.5 mm),
It may cool down rapidly. In addition, by doing this, the cylindrical film maintains its circular shape, making it easier to cover.

Further, by applying pressure and blowing into the air hole 16 of the mandrel pipe 2, it is possible to improve the slippage between the cylindrical film 5, the mandrel pipe 2, and the cooling mandrel 7, thereby making it easier to take it off.

The present invention is a method for manufacturing a tube container body as described above, in which the cylindrical film 5 is passed through the die head 9 to be appropriately heated and easily fused to the molten parison, and then cooled after fusion. Because the mandrel efficiently and uniformly cools and shapes,
It is highly productive and can produce seamless tubes with smooth surfaces, making it suitable for secondary processing such as printing, foil stamping, and varnishing.
A desired cross-sectional shape can also be obtained. In addition, the thickness of the cylindrical film can be considerably thinner than the overall thickness, and the change in thickness near the fused surface of the cylindrical film end can be kept small, so the cylindrical film can be heated without applying excessive pressure. This is an excellent method for manufacturing a seamless tube container body, in which the ends can be fused together and a cylindrical film containing a metal layer is used, so good barrier properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an apparatus for implementing the manufacturing method of the present invention, and FIG. 2 is an explanatory diagram showing an apparatus of another embodiment. 1 laminated film, 2 mandrel pipe, 3 film guide, 4 sealing machine, 5 cylindrical film, 6 cooling tube, 7 cooling mandrel, 8 extruder, 9 die head, 10 space, 11 melting parison, 12 coated cylindrical film.

Claims (1)

[Claims] 1. In advance, a film laminated in the order of at least an adhesive resin layer, a metal layer, and an adhesive resin layer is rolled up and the overlapping parts are fused to form a cylindrical film, and this cylindrical film is passed through a die head and extruded from the tip of the die head. The outer surface of the cylindrical film is coated with the molten parison outside the die head, and the coated cylindrical film is cooled by a cooling mandrel with a taper of 0.1/100 to 2/100 provided inside the cylindrical film. A method for manufacturing a tube container body characterized by a shape.