JP5789910B2 - Plastic bubble sheet, manufacturing method and manufacturing apparatus thereof - Google Patents

Description

The present invention relates to a plastic foam sheet having a uniform thickness, and also relates to a method and apparatus for producing such a plastic foam sheet. According to the present invention, a plastic foam sheet is provided in which the basis weight (weight per unit area of the product plastic foam sheet) is reduced to a possible limit while exhibiting the required buffer performance and maintaining the required strength. Furthermore, according to the present invention, a method for producing a plastic foam sheet with reliable back film fusion to the cap film and improved transparency is provided, and a back film pressure roll is not required from the production apparatus.

A plastic bubble sheet made of plastic, typically polyethylene, and a cap film in which a large number of caps are formed by vacuum forming and a flat back film are bonded together to form a large number of sealed air chambers. It is mainly used in the field of shock-absorbing packaging and partly as a heat insulating material. There is a three-layer product in which another flat liner sheet is bonded to the two-layered air bubble sheet with the top of the cap sheet.

As long as this plastic foam sheet can be manufactured with as little material as possible, as long as it has the buffering performance or thermal insulation performance necessary for its application, the manufacturing cost can be reduced and the consumption of resources can be reduced. In addition, when the used bubble sheet is disposed of by incineration, the amount of carbon dioxide generated can be suppressed, which is preferable.

On the other hand, if the thickness of each film constituting the above three-layer plastic bubble sheet is increased, the rigidity is increased and a plastic bubble board is obtained. This bubble board can be used as a plastic hollow plate. Polypropylene is the most suitable material for this type of plastic hollow plate. Plastic hollow plates made of polypropylene have been widely used as structural materials for various products including automobile parts and containers.

As shown in FIG. 2, the production of the above two-layer air bubble sheet is usually a metal cylinder in which a cap film is formed so as to be rotatable, and a large number of cap-shaped cavities are formed on the surface thereof. The cap film (I) in a plasticized state is vacuum formed using a vacuum forming roll (2) provided and connected to a vacuum suction device at the bottom, and the cap film is placed on the vacuum forming roll. Meanwhile, the back film film (II) in a plasticized state is fused to the bottom surface of the cap by pressing it using a pressure roll (3).

This pressure roll (3) is generally used in which a rubber layer is provided on a steel roll and a fluororesin coating is applied. The role of the pressure roll is to cool the outside of the back film that is not fused, in addition to pressing the back film (II). However, the cooling must be modest because if it proceeds excessively, it will incompletely fuse the back film to the cap film. In particular, when the back film is thin or when the line speed is slow, the degree of cooling requires delicate control. In addition, the pressure roll has a maintenance problem. This also reflects the cost, because when a fluororesin coating is damaged, it is transferred to the surface of the back film and must be replaced frequently.

In the actual production of film, it is proposed to use a pinning device for bringing a molten film into close contact with a cooling roll for the purpose of producing a film with high transparency and low shrinkage in the width direction even at a high take-off speed. (Patent Document 1). With this pinning device, an electrode wire was actually stretched parallel to the axial direction of the cooling roll, a high DC voltage was applied between the electrode wire and the cooling roll, and the film was extruded from the T die into a film. It follows the principle of causing static electricity to the material so that the film-like material is brought into close contact with the cooling roll. However, Patent Document 1 does not specifically disclose where the electrode wire should be positioned in relation to the cooling roll and the film, and how much voltage should be applied.
JP 2004-255720 A

The inventors have used vacuum suction using a discharge device as a means for pressurizing the back film toward the vacuum forming roll in which the cap is attached to the cavity, which has just been vacuum formed from a film for a cap film. Attempting to do so, despite the presence of the cap film on the roll, the back film adheres to the bottom surface of the cap film without disturbing what was intended, and a reliable fusion can be realized. It could be confirmed. Thereby, the roll for pressurizing the conventionally used back film became completely unnecessary.

As a result of further research, it has been found that when the back film is brought into close contact with the cap film by utilizing electrostatic attraction, unevenness of the thickness generated in the back film can be avoided. The inventors pursuing that mechanism have found that the pressure rolls used in the prior art "crush" the back film to some extent when fusing the back film to the cap film. . In fact, the crushing phenomenon is caused by an error (fusing of nearly 10%) of the weight per unit area of the cap-back fused portion of the conventional two-layer plastic bubble sheet measured with respect to the weight of the entire bubble sheet. It was confirmed from the fact that the wearing part is lightweight.

Thus, when the distribution of the thickness of the portion constituting the bubbles of the back film was examined, it was found that a cross-sectional shape and a thickness distribution as exaggerated in FIG. 1A were generated. In other words, the back film close to the rising part of the side wall of the bubble gathers the material pressed from the periphery in the surface direction, and becomes thicker than the cap / back fused part, while the central part of the bubble is added. It is pushed and thinned by the presence of an air layer sandwiched between the pressure roll and the back film. On the other hand, if the back film is brought into close contact with the bottom of the cap film by electrostatic force, the force is not applied to the back film as much as the pressure roll is applied, so the material will not be pushed and move. As shown in 1B, an ideally uniform wall thickness is realized. In this way, the method of using static electricity for the adhesion of the back film to the bottom of the cap film is practically capable of achieving the same level of cap crushing strength even if a thinner film is used as the back film. Profited.

As an improvement with respect to the apparatus, with the abolition of the pressure roll, it became easy to rapidly cool the back film closely attached to the cap film with an air knife, thereby increasing the transparency of the back film. Further, in some cases, a small-diameter water-cooled roll can be placed between the static electricity generator and the peeling roll. This enables an embodiment in which an arbitrary laminate substrate is bonded onto the back film.

The object of the present invention is to utilize the new knowledge obtained by the above-described inventors, basically, a back film is bonded to the bottom of a cap film having a large number of caps, and a large number of sealed air is adhered. In the plastic foam sheet that forms the chamber, the material usage efficiency is higher, the basis weight is lower than the conventional product, the equivalent cap crushing strength is exhibited, and therefore the conventional buffer performance can be exhibited. It is to provide.

A further object of the present invention is, firstly, a method for producing a plastic foam sheet as described above, wherein a plastic foam sheet with improved transparency and reliable fusion of the back film to the cap film is produced. It is to provide a way to do. The second is to provide an apparatus for producing the above-mentioned plastic bubble sheet, which does not require a back film pressure roll. A third object is to provide an apparatus for manufacturing the above-described plastic bubble sheet, which is laminated on a back film.

The plastic bubble sheet of the present invention comprises a cap film having a large number of cap-shaped protrusions made of plastic and a flat back film bonded to the bottom surface of the cap, and has a large number of sealed air chambers. As shown in FIG. 1B, the thickness of the back film is 16 μm or less, the average variation in the thickness of the back film is within ± 10%, and the basis weight is 35 g / m ² or less. A plastic bubble sheet. The plastic foam sheet of the present invention manufactured using an appropriate material can secure a cap crushing strength of 40 N / piece when a cap having a diameter of 10 mm and a height of 3.5 mm is taken as an example.

The method of the present invention for producing such a plastic foam sheet, the plastic foam sheet having the above structure,
A) A large number of dents are provided in a rotating metal cylinder, and a plastic film in a thermoplastic state is supplied to a forming roll in which the bottom of the dent is connected to a vacuum suction source. And B) on the bottom surface of the cap film formed in this manner, while the cap film is on the vacuum forming roll, it is melt-extruded from the T-die and is in a thermoplastic state. In the method of manufacturing by bringing the back film into contact and fusing,
A discharge device is placed at a position immediately before the back film contacts and fuses to the bottom surface of the cap film, a high-voltage DC voltage is applied between the discharge device and the vacuum forming roll, and the discharge device and the vacuum forming roll are By performing a discharge through which a discharge current passes on a plane connecting the center and causing the back film to be charged with static electricity, the back film is attracted to the vacuum forming roll by static electricity so as to be in close contact with the bottom surface of the cap film. It is characterized by promoting the fusion of.

As described above, since the thickness of the back film is uniform in the plastic foam sheet of the present invention, there is no thin portion that becomes a weak point in strength in the cap, at least in the back film. It is only necessary to pay attention to such a portion that is thin in principle in the molding process. That is, the back film can be thinned to its limit. Specifically, the weight of the plastic foam sheet made of ordinary polyethylene is lowered from 40 g / m ² which has been the lower limit so far, and 35 g / m ² or less is sufficient as described above. I made it.

When using the method of the present invention for producing a plastic foam sheet, the back film that has been drooped in the plasticized state is sucked toward the vacuum forming roll by the action of static electricity. It adheres to the bottom of the cap of the cap film that has just been made and is securely fused. At this time, since the back film is not cooled by the pressure roll as in the conventional manufacturing method, it is kept in a completely plasticized state and has sufficient heat. The cap film is completely fused, and an incompletely fused portion does not occur. As a result, the obtained plastic foam sheet is highly transparent.

As described above, according to the prior art, it was necessary to appropriately control the degree of cooling of the back film by the pressure roll. However, according to the present invention, the problem was automatically solved, and the back film was Even when it is thin or when the line speed is low, it will not be bothered by subtle control of cooling. The abolition of the pressure roll has solved the problems associated with its maintenance at the same time, so it eliminates the problem that the damage of the fluororesin coating is transferred to the product, and is advantageous not only for maintaining the quality of the product. This is also advantageous in terms of cost.

As for the equipment, a discharge device and its power supply are required instead of the pressure roll, but the equipment cost is very small, and the operation cost such as power consumption is not enough. It should be noted that the absence of the pressure roll means that the danger of workers being caught between the vacuum forming roll and the pressure roll is eliminated, and the safety of the work environment is greatly improved. .

Until now, it was not expected that the thickness of the back film of the plastic foam sheet would be uneven. The inventors have noticed that the thickness of the part where the cap film and the back film are fused is not a value representative of the overall basis weight, and in pursuit of the cause, as shown in FIG. I learned that there is a thick part to go around. When the back film is fused to the cap film that has been cap-formed by the vacuum forming roll, this uneven thickness is moved in the surface direction by the molten portion of the back film being pushed by the pressure roll. It is understood that it was caused by the mechanism of entering and calming down. Moreover, since air is sandwiched between the pressure roll and the back film by pressing the pressure roll, and the center part of the bottom surface of the back film cap is pushed into the cap, the back film in the center part tends to be thin. is there.

Naturally, the uneven thickness of the back film caused by the above-mentioned causes works against the crushing strength of the cap. In accordance with the present invention, if the back film is adhered to the cap film using static electricity and the pressure roller is eliminated, all the uneven thickness that has occurred in the back film due to the above causes is eliminated, and the back film The thickness contributes most efficiently to improving the crushing strength of the cap. In this way, the air bubble sheet of the present invention has higher strength even with the same basis weight.

The cap film needs to be in a thermoplastic state when it is formed in contact with a vacuum forming roll, and in order to realize the conditions most directly, a film extruded from a T-die is plasticized. The so-called “direct method”, which is supplied to the vacuum forming roll during the period of time, is simple. On the other hand, there is a so-called “reheating method” in which a plastic material once made into a film is used and heated as it is brought into contact with a heating roll while it reaches the vacuum forming roll, and supplied as a plasticized state. The manufacture is carried out when it is desired to manufacture a particularly stiff product. In carrying out the present invention, either a direct method or a reheating method is possible.

As shown in FIG. 2, the plastic bubble sheet manufacturing apparatus of the present invention comprises a cap film made of plastic and having a large number of cap-shaped protrusions, and a flat back film bonded to the bottom surface of the cap. An apparatus for producing a plastic foam sheet, each of the following parts:
A) T-die (1B) for extruding the back film (II) in a thermoplastic state;
B) A vacuum forming roll (2) having a number of dents and vacuum suction means for forming a plastic film for a cap film in a thermoplastic state into a cap film by vacuum forming;
C) A peeling roll (4) for separating the plastic foam sheet (III) formed by fusing the back film on the bottom surface of the cap film from the vacuum forming roll,
D) Winding means that takes up the plastic bubble sheet to form a coil;
In an apparatus for producing a plastic foam sheet having
A number of discharge needles (6A) made of a conductive material as shown in FIG. 4 are arranged in parallel, slightly above the line where the back film descending in the thermoplastic state contacts the cap film on the vacuum forming roll. Disposing the discharge substrate (6B) planted at equal intervals and providing means for changing the position of the discharge substrate while maintaining parallelism between the straight line connecting the tips of the discharge needle and the axis of the vacuum forming roll, Further, the present invention is characterized in that means (7) for applying a high-voltage DC voltage having a variable value is provided between the discharge needle and the vacuum forming roll.

The apparatus having the configuration shown in FIG. 3 includes a T-die (1A) for extruding a plastic film (I) for a cap film in a thermoplastic state and supplying it directly to a vacuum forming roll (2). , An apparatus for carrying out the direct method described above. In the apparatus for carrying out the reheating method, instead of the T-die (1A), a means for feeding out a plastic film for a cap film from a coil, and a heating roll for heating the fed film into a plasticized state Is provided.

In carrying out the present invention, as shown in FIG. 6, the discharge current flows stably and continuously on the plane (P) from the tip of the discharge needle toward the axis of the vacuum forming roll without departing from the surface. It is important to secure the condition. First, the straight line connecting the tip of the discharge needle and the axis of the liner pressurizing roll are completely parallel, and the distance (L) between the tip of the discharge needle and the surface of the vacuum forming roll is made constant. In addition to this, the position of the plane (P) through which the discharge current passes must be selected appropriately. Furthermore, for the stability and continuity of the discharge, it is important to select the value of the DC voltage to be applied and the distance from the discharge needle to the vacuum forming roll, which depends on the characteristics of the plastic used and the thickness of the back film. Choose according to your needs. Although this requires some trial and error, those skilled in the art will refer to the examples described later, the applied DC voltage is 25 to 50 kV, and the distance between the tip of the discharge needle and the vacuum forming roll surface is 50 to 100 mm. From the range, appropriate conditions can be easily found.

The direction in which the high-voltage DC voltage is applied is selected according to the type of plastic used as the material. The choice depends on whether the plastic is easily positively charged or negatively charged when placed in a high-voltage DC electric field. In the former case, the liner pressure roll is positive and the discharge needle is negative. In the latter case, on the contrary, the discharge needle is positive and the liner pressure roll is negative. Specifically, nylon tends to be positively charged, and polyolefin such as polyethylene and polypropylene tends to be negatively charged. Polyester and polystyrene will also be negative.

Since the film (I) and the back film (II) for the cap film constituting the plastic foam sheet of the present invention are both processed in a thermoplastic state, the plastic film melt-extruded from the T-die It is advantageous to use As shown in FIG. 2, if all the two sheets are melt-extruded and supplied from the T-die (1A, 1B), complete in-line operation is possible. However, the same processing conditions, that is, the state of being thermoplasticized, can also be realized by winding these separately-manufactured sheets on a reel and then feeding them out to contact a heating roll and heating them to a required temperature. In some cases, direct melt extrusion from the above-mentioned T-die and plasticization with a heating roll can be used in combination.

Another embodiment of the apparatus of the present invention used for producing a plastic foam sheet has a function of laminating a laminate substrate composed of another film or sheet on a back film, As shown in FIG. 7, the apparatus has a configuration in which a laminating roll (8) is provided on the vacuum forming roll (2) after the discharge needle (6A). The laminating roll (8) does not have the meaning of eliminating the pressing roll when subjected to strong pressurization, and therefore, the laminating roll (8) has a pressurizing force that is pressed to the limit necessary for laminating the laminate base material. Temperature control is important for this roll, and it is usually cooled through cold water inside, but in some cases, excessive cooling is prevented through hot water. The temperature is determined in consideration of various factors such as the type and thickness of the laminate substrate, the type and thickness of the back film, the temperature when contacting the cap film, and the line speed. In this apparatus, as shown in the figure, an air knife (9) can be placed after the laminating roll (8) to cool the laminated material composed of the cap film, the back film, and the laminating substrate, as shown. Cooling helps to clear the product bubble sheet and achieve high line speed.

The material of the plastic foam sheet of the present invention is not particularly limited as long as it is thermoplastic and can be formed into a film, but polyethylene and polypropylene, or a blend of both, which are particularly useful as the material of the plastic foam sheet, are available. Can be used preferably.

The sheet thickness and basis weight of the product, as well as the diameter and height of the cap, the arrangement and density, and the like are selected according to the physical characteristics and cushioning performance desired in relation to the plastic foam sheet application. Speaking of things that are used for buffer wrapping materials and ordinary uses such as curing materials for moving and remodeling work, the thickness of the film is generally in the following ranges,
Cap film: 10 to 180 μm,
Back film: 7.5 to 150 μm,
This thickness corresponds to 30 to 300 g / m ² in basis weight. As described above, according to the present invention, the lower limit of the basis weight of the bubble sheet having a sufficient bubble crushing strength as a cushioning material, which has been practically set as the lower limit of 40 g / m ^2, is 35 g / m ² . In the aspect, it was possible to reduce to 30 g / m ² .

The diameter of the bubble sheet cap is generally in the range of 3 to 15 mm, and the height is generally in the range of 3 to 15 mm. Arrangement can be arbitrarily selected, such as staggered arrangement, lattice arrangement, and oblique lattice arrangement. The staggered arrangement performed on the bubble sheet is preferable in that it has no directionality, but in some cases, a lattice arrangement may be advantageous. Needless to say, an optional additive such as a colorant, a filler, an antioxidant, an antistatic agent, an antibacterial agent, and a combustion auxiliary agent can be added to the plastic foam sheet of the present invention.

The bubble sheet manufacturing apparatus of the present invention was manufactured as follows. That is, needles made of metal having a thickness of 2 mm and a length of 20 mm and having a sharp tip were planted on a metal discharge substrate at an interval of 10 mm. Targeting a vacuum forming roll having a diameter of 300 mm and provided with a cooling water flow path, the above-described discharge device is disposed so that the distance (L) between the tip of the discharge needle and the roll surface is about 75 mm. . The plane (P) where the discharge current flows, that is, the straight line (C ² ) where the plane connecting the tip of the discharge needle and the axis of the vacuum forming roll crosses the back film is the back film when the back film is not adhered by discharge. It is about 15 mm above the straight line (C ¹ ) that contacts the vacuum forming roll.

The air bubble sheet manufacturing apparatus prepared as described above is provided, and the apparatus shown in FIG. 2 is configured to extrude and supply all of the two types of sheets from the T-die. LF10 "(manufactured by Tosoh Corporation) was used to produce a plastic foam sheet. The extrusion thicknesses of the two types of film are as follows:
Cap film: 35 μm
Back film: 25μm
The cap has an outer diameter of 10 mm, a pitch of 11.5 mm, and a staggered arrangement.
When a DC voltage of 30 kV is applied so that the discharge needle side is positive and the vacuum forming roll side is negative, stable discharge that passes through the 25 μm-thick back film continues, and the back film is vacuumed. The film was drawn to the forming roll and adhered to the cap film in a straight line.

The obtained plastic foam sheet has a thickness of 60 mm and a basis weight of 55 g / m ² . The adhesion between the back film and the cap film of this product was almost complete, and the portion showing poor fusion was extremely rare.

PE “Petrocene 213” (manufactured by Tosoh Corp.) was used as a material, and the extruding thicknesses of the two types of films were as follows, and a foam sheet with a basis weight reduced to 35 g / m ² was produced.
Cap film: 28μm
Back film: 10μm
As with the first embodiment, the cap has an outer diameter of 10 mm, a pitch of 11.5 mm, and a staggered arrangement.

The cap was cut at the center along the axis, and the thickness of the back film located at the bottom was measured. The maximum value of the thickness was 10.5 μm, the minimum value was 9.5 μm, and the variation in thickness was ± 5%. This cap exhibited a crush strength of 47 N / grain.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which expanded the cross section of the cap a little, and was shown in order to explain the improvement of the plastic bubble sheet of this invention, Comprising: A is a cap by a prior art, B is the cross section of the cap of this invention Show. Sectional drawing which shows the structure of the conventional apparatus for demonstrating the manufacturing method of the plastic foam sheet of this invention. Sectional drawing corresponding to FIG. 2 which shows the structure of the apparatus for demonstrating the manufacturing apparatus of the plastic foam sheet of this invention. The top view which shows the apparatus provided with the discharge needle for making the back film closely_contact | adhere to the vacuum forming roll by electric discharge characterizing the manufacturing technique of the plastic air bubble sheet of this invention. Sectional drawing which shows the case where the apparatus of FIG. 4 was used for the manufacturing technology of the plastic bubble sheet | seat of this invention, but the contact | adherence by discharge is not performed. FIG. 5 is a cross-sectional view showing a slightly exaggerated case in the case of close contact by electric discharge in the apparatus of FIG. Sectional drawing corresponding to a part of FIG. 3 which shows the principal part of an apparatus for demonstrating another aspect about the manufacturing apparatus of the plastic foam sheet of this invention.

1A, 1B T-die 2 Vacuum forming roll 3 Back film pressure roll 4 Peeling roll 6A Discharge needle 6B Discharge substrate 6C Discharge needle tip 7 DC voltage application device 8 Laminating roll 9 Air knife I Cap film
II Back film
III Plastic bubble sheet P Plane through which discharge current passes (Plane connecting the tip of the discharge needle and the axis of the vacuum forming roll)
L Distance between the tip of the discharge needle and the surface of the vacuum forming roll C ¹ Straight line where the back film contacts the vacuum forming roll (when no discharge is performed)
Straight C ² back film contacts the vacuum forming roll (case of performing the discharge)

Claims (7)

A plastic bubble sheet comprising a plastic film, a cap film having a large number of cap-shaped protrusions, and a flat back film bonded to the bottom surface of the cap, and having a large number of sealed air chambers. A plastic foam sheet having a thickness of 16 μm or less, a variation in thickness of the back film within ± 10%, and a basis weight of 35 g / m ² or less. A plastic bubble sheet made of plastic and made of a cap film having a large number of cap-shaped protrusions and a flat back film bonded to the bottom surface of the cap, and having a large number of sealed air chambers,
A) A large number of dents are provided in a rotating metal cylinder, and a plastic film in a thermoplastic state is supplied to a forming roll in which the bottom of the dent is connected to a vacuum suction source. And B) on the bottom surface of the cap film formed in this manner, the cap film is melt-extruded from the T-die while being on the vacuum forming roll, and is brought into a thermoplastic state. In the method of manufacturing by bringing a certain back film into contact and fusing,
A discharge device is placed at a position immediately before the back film contacts and fuses to the bottom surface of the cap film, a high-voltage DC voltage is applied between the discharge device and the vacuum forming roll, and the discharge device and the vacuum forming roll are By performing a discharge through which a discharge current passes on a plane connecting the center and causing the back film to be charged with static electricity, the back film is attracted to the vacuum forming roll by static electricity so as to be in close contact with the bottom surface of the cap film. A method for producing a plastic foam sheet, characterized in that fusing is promoted. Stable discharge by selecting the value of DC voltage applied between the discharge device and the vacuum forming roll and the distance between the discharge device and the vacuum forming roll according to the characteristics of the plastic used and the thickness of the back film The method for producing a plastic foam sheet according to claim 2, which is carried out while maintaining the close contact of the back film with the cap film. A plastic bubble sheet comprising a cap film having a large number of cap-shaped protrusions and a flat back film bonded to the bottom surface of the cap, and having a large number of sealed air chambers. And the back film are both polyethylene, each having a thickness in the following range,
Cap film: 10 to 180 μm
Back film: 7.5 to 150 μm,
In addition, a method for producing a plastic bubble sheet having a back film thickness variation within ± 10% and a basis weight of 30 to 300 g / m ² , wherein the discharge device is positive and vacuum forming is performed. The manufacturing method of Claim 2 which implements by applying the DC voltage from which a roll becomes negative, selecting the voltage from 25-50 kV, and the distance of the front-end | tip of a discharge device and the surface of a vacuum forming roll from 50-100 mm. An apparatus for producing a plastic bubble sheet composed of a cap film having a large number of cap-shaped projections made of plastic and a flat back film bonded to the bottom surface of the cap, each of the following parts:
A) T-die (1B) for extruding the back film (II) in a thermoplastic state;
B) A vacuum forming roll (2) having a number of dents and vacuum suction means for forming a plastic film for a cap film in a thermoplastic state into a cap film by vacuum forming;
C) A peeling roll (4) for separating the plastic foam sheet (III) formed by fusing the back film on the bottom surface of the cap film from the vacuum forming roll,
D) Winding means that takes up the plastic bubble sheet to form a coil;
In an apparatus for producing a plastic foam sheet having
Discharge in which a large number of discharge needles (6A) made of a conductive material are planted in parallel and equally spaced slightly above the line where the back film descending in the thermoplastic state contacts the cap film on the vacuum forming roll The substrate (6B) is disposed, and means for changing the position of the discharge substrate is provided while maintaining the parallel between the straight line connecting the tips of the discharge needle and the axis of the vacuum forming roll, and further, the discharge needle and the vacuum forming are provided. A manufacturing apparatus comprising means (7) for applying a high-voltage DC voltage having a variable value between the roll and the roll. The manufacturing apparatus of Claim 5 provided with the T-die (1A) for extruding the plastic film (I) for cap films in a thermoplastic state, and making it directly to a vacuum forming roll. In addition to the constituent parts according to claim 5, further comprising e) a laminate roll (8) on the vacuum forming roll (2) and after the discharge needle (6A), and
(F) The manufacturing apparatus according to claim 5 or 6, wherein an air knife (9) is arranged after the laminate roll (8).

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