JP4747728B2 - Method and apparatus for producing plastic foam sheet in which laminate film is bonded to back film - Google Patents

Description

The present invention relates to a method for producing a product in which a laminate film is bonded to a back film in a plastic foam sheet, and also relates to an apparatus used for carrying out the method.

The plastic film is vacuum-formed to form a cap film having a large number of cap-shaped protrusions, and a flat back film is bonded to the bottom surface of the cap to form a plastic bubble sheet (hereinafter referred to as “bubble” Sheet ") is widely used for cushioning packaging and other applications.

Among these air bubble sheets, there are products in which another flat laminate film is laminated on a back film to have various functions. The role of the laminate film is various, such as giving a color or a pattern, giving a gas barrier property, giving heat ray reflection performance, and the like. Whatever film is selected, a common problem in laminating the laminate film to the back film is that it is difficult to completely adhere the back film and the laminate film.

Specifically, it is a phenomenon in which air is caught between the back film and the laminate film at a portion that hits the bottom of the cap to form a substantially circular lens-like space. This not only significantly detracts from the aesthetics of the product, but also has a disadvantage with regard to the performance that should be obtained with the laminate. FIG. 2C is an enlarged cross-sectional view of the cap portion, exaggerating this phenomenon.

The first possible cause for this is that the volume of the air chamber formed by bonding the back film to the cap film shrinks due to a decrease in temperature after formation. That is, the cap film vacuum-formed from the melted state is high because the back film to be bonded to the cap is also in a molten state, but after bonding, the vacuum forming roll is made of metal, Usually, the temperature is rapidly lowered because it is cooled from the inside. For example, if the temperature in the air chamber, which was 100 ° C. when the cap was formed, decreased to 20 ° C., the volume of the air contracts to about 80%. The change from A in FIG. 2, that is, when the back film is applied to B in FIG. 2, that is, when the laminate film is applied, indicates the situation during this period.

Another reason is that this is also a principle, and as shown in FIG. 3, the vacuum forming roll has a circular cross section, so when considered along the line passing through the center of the cavity, the back film (BF) While the pass line is a straight line connecting the front and rear edges of the cavity (41), the surface on which the cap film (CF) and the back film are bonded is an arc. This is a phenomenon that the back film is recessed toward the cap film by an amount corresponding to the difference between the straight line and the arc. The laminate film (LF) bonded thereon is also pressed by the pressure roll (5) along the arc-shaped cross section of the vacuum forming roll (4), and as a result, as shown in FIG. A lens-shaped space (S) is created.

The object of the present invention is to provide a product in which two sheets of film are completely in contact with each other in the air bubble sheet laminated on the back film without air entrainment between the back film and the laminate film as described above. It is providing the manufacturing method of the foam sheet which can be obtained. Providing an apparatus for use in carrying out the method is also included in the object of the present invention.

The method for producing a plastic bubble sheet in which a laminate film is bonded to a back film of the present invention is provided with a large number of cavities on the surface of a metal cylinder and connected to a vacuum suction path in which the bottoms of the cavities are opened in the axial direction of the cylinder. The vacuum forming roll is used to vacuum form a plastic film to form a cap film having a large number of cap-shaped protrusions, and a flat back film is bonded to the bottom surface to form a large number of sealed air chambers. In addition, in the method of manufacturing a plastic foam sheet comprising laminating another flat laminate film to the back film,
Pressurized air is immediately sent through the vacuum suction path to the cavity where the cap film has been vacuum-formed to release the cap restraint by the cavity, and the back film is slightly swollen to the laminate film side, and the above bonding is performed. In the manufacturing method, a plastic foam sheet having a laminate film in which no air is caught between the back film and the laminate film is obtained by performing the bonding.

According to the method of the present invention, if a plastic bubble sheet in which a laminate film is bonded to a back film is manufactured, the cap film is sucked into the cavity to give a cap shape, and the back film is bonded to form an air chamber. By the way, as soon as the pressurized air is sent from the back of the cavity, the restraint on the cavity of the cap is released, and a force in the direction of pushing out acts on the cap. Since the force is transmitted to the back film through the air in the air chamber, the back film does not dent toward the cap as shown in FIG.

Behind the laminate film is a pressure roll made of a flexible material such as rubber. Therefore, the back film and the laminate film are separated from the surface of the vacuum forming roll and the pressure roll in the part without the cap. In the part with the cap sandwiched between the surface and pressed by the pressure of the air in the air chamber, it is brought into close contact by the force of the pressure roll, so in the end, all the air that was between the back film and the laminate film is The pasting is completed while being pushed out between the two. If this situation is seen for the cap portion, it is as shown in FIG.

The apparatus of the present invention for carrying out the above method for producing a bubble sheet is a method of vacuum forming a plastic film to form a cap film having a large number of cap-shaped protrusions, and laminating a flat back film on the bottom surface of the cap. 1 is a device for producing a plastic bubble sheet by forming a large number of sealed air chambers and attaching another flat laminate film to a back film, and the entire structure is conceptually shown in FIG. In addition to the first flat die (1) for melt extruding the cap film, the second flat die (2) for melt extruding the back film, and the means (3) for supplying the laminate film, a metal cylinder A number of cavities (41) are provided on the surface of the cylinder and penetrated in the axial direction of the cylinder to connect the cavities to a vacuum source. And a vacuum forming roll (4) having a vacuum suction path (43) having an opening (42) at the end of the cylinder, means for supporting and rotating the vacuum forming roll, and a constant rotation angle of the vacuum forming roll. Manufactured with a flexible material for bonding the back film and the laminate film to the bottom of the vacuum formed cap film (7) for connecting the vacuum suction passage opening within the range to the vacuum source. Pressure roll (5), peeling roll (6) for peeling the produced plastic foam sheet from the vacuum forming roll, and means for taking up and winding the peeled plastic foam sheet, In a device constructed by adding
An air supply duct (8) for supplying pressurized air to the vacuum suction path is added to the position following the vacuum duct area with respect to the rotation angle of the vacuum forming roll, and the back film is slightly swollen to the laminate film side. By bonding, a plastic bubble sheet having a laminate film in which no air is caught between the back film and the laminate film is obtained.

In FIG. 1, the vacuum source and the pressure air source are not shown, but the former is opened through the vacuum duct (7) and the latter through the air supply duct (8) to the vacuum suction path (43) of the vacuum forming roll. It connects via a part (42). Although the rotation driving means of the vacuum forming roll is not shown, a means for rotating the shaft (44) may be provided. The pressure of the pressurized air supplied through the air supply duct (8) should be about 10 mm as a water column at the entrance of the vacuum suction path.

A vacuum forming roll having an effective width of 600 mm was manufactured by providing a circular cavity having a diameter of 10 mm and a depth of 4 mm in a staggered arrangement with a pitch of 11.5 mm in a metal cylinder having an outer diameter of 200 mm. Forty-eight cavities are arranged on the circumference. The vacuum forming roll was combined with a pressure roll having a diameter of 150 mm and a peeling roll having a diameter of 150 mm to assemble a bubble sheet manufacturing apparatus having the configuration shown in FIG. As shown in the figure, the rotation angle at which the air supply duct (8) is connected to the vacuum suction path of the vacuum forming roll is in the range of 15 degrees before and after the contact point with the pressure roll, while the vacuum duct ( The rotation angle connected by 7) is in the range of 45 degrees ahead of the rotation angle connected by the air supply duct. Speaking of the cavities, on the circumference of the vacuum forming roll, vacuum suction is performed on the six rows of cavities to form caps, and then the back film and the compressed air are blown out to the last row. The laminate film is laminated, and pressurized air is still supplied to one row even after the lamination film is laminated.

Using this device, the LLDPE film was supplied so that the thickness of the cap film was 35 μm and the thickness of the back film was 20 μm, the laminate film of 30 μm thickness was supplied, and the back film at a line speed of 20 m / min. A bubble sheet with a laminate on the side was produced. When the supply of pressurized air from the air supply duct was not performed, air entrainment between the back film and the laminate film at the bottom of the cap was unavoidable, whereas compressed air was supplied from the air supply duct according to the present invention. When supplied, air entrainment was prevented and a beautiful laminate was realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view conceptually showing main constituent parts of a plastic bubble sheet manufacturing apparatus in which a laminate film is bonded to a back film of the present invention, and showing a cavity by cutting out a part of a vacuum forming roll. In the conventional plastic bubble sheet, it is an expanded sectional view explaining the mechanism in which air is involved while laminating the laminate film to the back film, where A is the stage where the back film is stuck to the cap film, and B is the back C represents a product bubble sheet, where the laminate film is bonded to the film. In the conventional plastic bubble sheet, the expanded sectional view of the cavity part of the vacuum forming roll explaining another mechanism in which air is wound while the laminate film is bonded to the back film. FIG. 3 is an enlarged cross-sectional view corresponding to FIG. 2B for explaining the reason why air is not caught between the back film and the laminate film in the production of the plastic foam sheet according to the present invention. It is explanatory drawing of the Example of this invention, Comprising: The conceptual diagram which showed the rotation angle which a vacuum duct and an air supply duct connect with respect to a vacuum forming roll in the experimentally produced plastic bubble sheet manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Flat die 3 Laminate film supply means 4 Vacuum forming roll 41 Cavity 42 Opening part 43 Vacuum suction path 44 Shaft 5 Pressure roll 6 Peeling roll 7 Vacuum duct 8 Air supply duct BF Back film CF Cap film LF Laminating film S Lens Space

Claims (2)

A plastic film is vacuum-formed using a vacuum forming roll in which a large number of cavities are provided on the surface of a metal cylinder, and the bottom of the cavities are connected to a vacuum suction path opened in the axial direction of the cylinder. A plastic formed by forming a cap film having protrusions and laminating a flat back film on its bottom to form a number of sealed air chambers, and laminating another flat laminate film to the back film In a method for producing a bubble sheet,
Pressurized air is immediately sent through the vacuum suction path to the cavity where the cap film has been vacuum-formed to release the cap restraint by the cavity, and the back film is slightly swollen to the laminate film side, and the above bonding is performed. A production method characterized by obtaining a plastic bubble sheet having a laminate film in which air is not caught between the back film and the laminate film by combining. A plastic film is vacuum-formed to form a cap film (CF) having a large number of cap-shaped protrusions, and a flat back film (BF) is bonded to the bottom surface of the cap to form a large number of sealed air chambers. An apparatus for producing a plastic foam sheet (BS) by laminating another flat laminate film (LF) to the back film, the first flat die (1) for melting and extruding the cap film, the back film In addition to the second flat die (2) for melt extrusion and means (3) for supplying the laminate film, a plurality of cavities (41) are formed on the surface of a metal cylinder, and these cavities are connected to a vacuum source. A vacuum suction path (43) having an opening (42) at the end of the cylinder, penetrating in the axial direction of the cylinder Vacuum forming roll (4), means for rotating and supporting the vacuum forming roll, vacuum duct (7 for connecting a vacuum source to the opening of the vacuum suction passage within a certain rotation angle range of the vacuum forming roll ), A pressure roll (5) made of a flexible material for bonding the back film and the laminate film to the bottom surface of the vacuum- formed cap film, and peeling the produced plastic bubble sheet from the vacuum forming roll In an apparatus consisting essentially of a roll (6), as well as means for taking up and winding up the peeled plastic bubble sheet, and adding a vacuum source thereto,
An air supply duct (8) for supplying pressurized air to the vacuum suction path is added to the position following the vacuum duct area with respect to the rotation angle of the vacuum forming roll, and the back film is slightly swollen to the laminate film side. A manufacturing apparatus characterized by obtaining a plastic bubble sheet having a laminate film in which air is not caught between the back film and the laminate film by performing the bonding.

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