JP6193018B2 - Air bubble sheet manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for producing a bubble sheet used for a cushioning material and the like, a production apparatus, and a bubble sheet produced by the production method.

  As a bubble sheet manufactured by a plurality of synthetic resin films, there are various types of two-layer structures including a cap film having a large number of protrusions and a back film attached to the protrusion opening side of the cap film. Are known. There are also various known three-layered bubble sheets that further include a liner film on the tip end side of the cap film.

  As an example of the method for producing the bubble sheet, a film made of a synthetic resin in a thermoplastic state is supplied to a vacuum forming roll to form a cap film having a large number of protrusions, and the cap film is placed on the vacuum forming roll. In the case of a three-layer structure, a thermoplastic film is further applied to the top surface of the cap film. And the liner film is bonded to the cap film by pressing the air bubble sheet using a nip roll.

  Conventionally, when the back film BF is brought into contact with the cap film CF and fused, a method using a pressure roll Z1 has been adopted as shown in FIG. 9, for example. Specifically, the back film BF is pressed by the pressure roll Z1 disposed immediately after the back film BF contacts the cap film CF, and is pressed against the cap film CF.

  Further, when the liner film LF is brought into contact with the cap film CF and fused in the three-layered air bubble sheet, for example, as shown in FIG. Had adopted the method. Specifically, the liner film LF is pressed against the cap film CF by pressing the liner film LF with the nip roll Z2 disposed immediately after the liner film LF contacts the cap film CF.

  In detail, the temperature of the pressure roll Z1 and the nip roll Z2 is set lower than the temperature at which the back film BF and the liner film LF are crystallized, and the back film BF and the liner film LF are pressed while being cooled. The back film BF and the liner film LF are bonded to the cap film CF.

  However, when the pressure roll Z1 and the nip roll Z2 are excessively cooled, the crystallization of the back film BF and the liner film LF proceeds excessively before being fused to the cap film CF, and the back film BF In addition, there is a problem that the liner film LF is not fused with the cap film CF.

  Further, as an important factor that affects the degree of fusion as well as the temperature, there is a pressure at the time of pressing the pressure roll Z1 or the nip roll Z2. Although the fusion tends to be promoted by increasing the pressure, if the pressure is too high, the molten resin is wound around the pressure roll Z1 or the nip roll Z2 and causes the trouble that causes the production line to stop. It was. In particular, if the pressure of the nip roll Z2 is too high when the liner film LF is attached to the cap film CF, the pressure between the cap film CF and the back film BF is caused by the pressure of the nip roll Z2 until no trouble occurs around the nip roll Z2. There was a problem that the air bubbles formed in this were crushed.

  Thus, the temperature and / or pressure management of the pressure roll and nip roll during the production of the bubble sheet has been a very severe problem.

  In addition, when the back film or liner film is brought into contact with the cap film and fused, a method using an electrode needle as shown in FIG. 10, for example, is also considered (see, for example, Patent Document 1 below). Specifically, when the back film is brought into contact with the cap film and fused, the back film is discharged by discharging from the discharge device equipped with the electrode needle, and the cap on the vacuum forming roll is caused by this static electricity. It is trying to adhere to the film. As schematically shown in FIG. 10, this discharge device has a large number of electrode needles W2 planted in parallel and at equal intervals on a discharge base W1, and a vacuum that is a metal body from the needle tips W3 of the electrode needles W2. The discharge is performed with a spread in a range of about 30 degrees toward the nearest portion of the forming roll W4. In FIG. 10, the image of the discharge current is shown as a pattern.

  In the method using the electrode needle, it is important to ensure that the discharge current flows stably and continuously on the plane from the tip of the discharge needle toward the axis of the vacuum forming roll without departing from the plane. Come. Specifically, it is necessary to keep the distance between the tip of the discharge needle and the surface of the vacuum forming roll constant, and to appropriately select the position of the plane through which the discharge current passes.

  Accordingly, when the discharge is performed with a spread of about 30 degrees from the electrode needles W2 arranged at a predetermined interval, voltage unevenness occurs in the width direction of the back film. In order to eliminate this voltage non-uniformity and secure the fusion between the cap film and the back film, it is conceivable to bring the electrode needle W2 closer to the back film side. However, a spark is generated between the electrode needle W2 and the back film, and another problem arises that it becomes difficult to maintain the quality of the product because the bubble sheet is burnt.

  Such a problem may occur between the liner film and the cap film as well.

JP 2010-585502 A

The present invention relates to a bubble sheet capable of solving the problems of temperature management and pressure management that occur when a plurality of films are bonded by a pressure roll, a nip roll, and the like, and a spark problem when an electrode needle is used. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus.

The method for producing an air bubble sheet according to the present invention is a method in which an intermediate processed product comprising a cap film having a large number of protrusions and a back film attached to the protrusion opening side of the cap film is placed on a nip roll while being thermoplastic. A method for producing a bubble sheet by bringing a liner film in a liquefied state into contact with the projection tip side of the cap film and fusing it, immediately before the liner film comes into contact with the projection tip side of the cap film and fused A high voltage direct current voltage is applied between the wire electrode disposed at the position of the wire and the nip roll by a voltage applying means to cause the liner film to be charged with static electricity, and the liner film is attracted to the nip roll by static electricity and It is characterized by being in close contact with the protrusion tip side.

  Here, the “nip roll” may be any one as long as it can hold an intermediate processed product composed of a cap film and a back film in a predetermined position. It is not restricted to what is arrange | positioned in a pair on both sides of.

In such a case, by using a wire electrode, the problems of temperature management and pressure management that occur when a plurality of films are bonded together by a nip roll, and spark problems when an electrode needle is used are enumerated. Can be resolved.

As a preferred embodiment of the wire electrode, one that can change the distance facing the liner film by a length adjusting means can be mentioned.

When the shortest distance between the surface of the wire electrode having a diameter of 0.1 to 0.2 mm and the liner film is set to 20 to 30 mm, the DC voltage applied between the wire electrode and the nip roll A specific example is one in which the value can be set to an arbitrary magnitude of 12 kV or more.

The air bubble sheet manufacturing apparatus according to the present invention is a method of thermoplasticizing an intermediate processed product comprising a cap film having a large number of protrusions and a back film attached to the protrusion opening side of the cap film on a nip roll. an apparatus for producing a bubble sheet by causing the liner film in a state fused in contact with the projecting tip end of the cap film, liner film descends in thermoplastic state of the cap film on the nip rolls A liner electrode is formed by applying a high-voltage DC voltage between the wire electrode and the nip roll between the wire electrode and the wire electrode arranged in parallel with the axial center of the nip roll at a position immediately before the contact with the tip of the protrusion. and voltage application means for causing electrostatically charged provided, intake to the nip roll liner film by static electricity It is characterized by being adapted to close contact with the projecting tip end of the cap film.

  Since the present invention is configured as described above, the problems of temperature management and pressure management that occur when a plurality of films are bonded together by nip rolls, and the problem of sparks when using electrode needles are all solved. can do.

The top view which expands and shows the bubble sheet concerning one Embodiment of this invention. The XX line end view of FIG. The side view which shows typically the manufacturing apparatus of the bubble sheet of the same embodiment. The top view which shows typically the principal part of the manufacturing apparatus of the bubble sheet of the same embodiment. The side view which expands and shows the principal part of the manufacturing apparatus of the bubble sheet of the embodiment. The top view which expands and shows the intermediate workpiece of the embodiment. FIG. 7 is an end view taken along line YY in FIG. 6. The side view which expands and shows the principal part of the manufacturing apparatus of the bubble sheet of the embodiment. The side view which shows typically the manufacturing apparatus of the conventional bubble sheet. The top view which shows typically the manufacturing apparatus of the conventional bubble sheet.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 3 and 8, the bubble sheet 1 of this embodiment is a hollow sheet having flexibility, and is made of a synthetic resin, for example, a polyolefin resin. Specifically, the bubble sheet 1 includes a cap film 11 having a large number of cap-shaped protrusions 13, a back film 12 attached to the cap film 11 on the opening side of the protrusion 13, and a tip end side of the protrusion 13 of the cap film 11. And a liner film 17 attached thereto. The air bubble sheet 1 is the same as a conventional product having a three-layer structure including a cap film 11, a back film 12, and a liner film 17. Materials include polyolefins such as polypropylene, ethylene- Vinyl acetate copolymer, nylon and many other types of plastics can be used.

  As shown in FIGS. 1 to 3 and FIGS. 5 to 8, the cap film 11 has a thickness dimension set to about 30 μm, for example. In addition, as for the thickness dimension of the cap film 11, 30 micrometers-90 micrometers are preferable. The cap film 11 has a large number of columnar protrusions 13, and each protrusion 13 has a circular shape in plan view as shown in FIGS. 1 and 6.

  As shown in FIGS. 1 to 3 and FIGS. 5 to 8, the back film 12 has a thickness dimension set to about 10 μm, for example. In addition, as for the thickness dimension of the back film 12, 10 micrometers-30 micrometers are preferable. The back film 12 is flat without irregularities, and is attached to the side of the cap film 11 where the protrusions 13 are opened, whereby a large number of sealed bubbles 14 are formed.

  As shown in FIGS. 1 to 3 and FIGS. 5 to 8, the bubble 14 has a cylindrical shape with a low shape, and has a diameter of about 6 mm to 50 mm and a height of about 2 mm to 30 mm. It is. In this embodiment, the diameter of the bubble 14 is set to about 10 mm, and the height is set to about 4 mm. The diameter of the bubbles 14 is preferably 6.5 mm to 10 mm, and the height of the bubbles 14 is preferably 2 mm to 4 mm. The bubbles 14 are arranged in a zigzag pattern with a pitch of about 11.5 mm in the flow direction, but are arranged in a straight line in the width direction.

  As shown in FIGS. 1 to 3 and 8, the liner film 17 has a thickness dimension set to about 10 μm, for example. In addition, as for the thickness dimension of the liner film 17, 10 micrometers-30 micrometers are preferable. The liner film 17 is a flat film having no irregularities.

  Thus, as shown in FIGS. 1 to 3 and FIGS. 5 to 8, the bubble sheet 1 of the present embodiment includes a flat portion 16 on the cap film 11 where the protrusions 13 are not formed, the back film 12, and the like. Many streaky bubbles 15 are formed between the two. Each streaky bubble 15 has an elongated shape extending in the flow direction of the bubble sheet 1 and has a different size and shape. Each streak-like bubble 15 is formed by a large number of sealed spaces formed by attaching the back film 12 to the flat portion 16 of the cap film 11 in a wave shape. Each streak bubble 15 has a length dimension of 2 mm or less and a width dimension of 1 mm or less. In particular, in the present embodiment, the streaky bubbles 15 have a length dimension of 1.3 to 1.4 mm or less and a width dimension of 0.4 to 0.5 mm or less. In addition, according to the manufacturing method using the conventional discharge needle | hook, the thing from which the magnitude | size of each streaky bubble 15 becomes a bigger value will also exist. That is, the bubble sheet 1 on which relatively small streaky bubbles 15 are formed appears as a raindrop, but since each streaky bubble 15 is small, it does not adversely affect the appearance.

  Next, the manufacturing apparatus 2 and manufacturing method of such a bubble sheet 1 will be described.

  As shown in FIGS. 3 to 5 and 8, the three-layered bubble sheet 1 includes dies 21, 22, and 31 that continuously supply a molten resin film, and a plurality of cavities 24 on the outer peripheral surface. It is made using the manufacturing apparatus 2 mainly composed of the formed vacuum forming roll 23 and the nip roll 32 for holding the back film 12 side of the bubble sheet 1. More specifically, the manufacturing apparatus 2 supplies a film made of a synthetic resin in a thermoplastic state to the vacuum forming roll 23 to form a cap film 11 having a large number of protrusions 13. The intermediate processed product 10 having a two-layer structure is obtained by bringing the back film 12 in the thermoplastic state while being on the vacuum forming roll 23 into contact with the projection 13 opening side of the cap film 11 and fusing it. In addition, the manufacturing apparatus 2 is configured to bring the liner film 17 in a thermoplastic state into contact with the front end side of the protrusion 13 of the cap film 11 and fuse the intermediate processed product 10 on the nip roll 32. A bubble sheet 1 having a three-layer structure is obtained.

  And the manufacturing apparatus 2 of this embodiment is the axis A1 of the said vacuum forming roll 23 in the position just before the back film 12 which descends in a thermoplastic state contacts the cap film 11 on the vacuum forming roll 23. And a voltage applying means 26 for applying a high DC voltage between the wire electrode 25 and the vacuum forming roll 23 to cause the back film 12 to be charged with static electricity. A discharge device is provided.

  As shown in FIGS. 3 to 5, the wire electrode 25 is made of metal such as tungsten, and is arranged in parallel with the axis A <b> 1 of the vacuum forming roll 23 by the holding bodies 27 and 28 provided at both ends. Yes. The wire electrode 25 of this embodiment uses a wire diameter of 0.15 mm. In addition, 0.1-0.3 mm is preferable and, as for the wire diameter of the wire electrode 25, 0.1-0.2 mm is more preferable. The wire electrode 25 preferably has a smaller wire diameter, but this is also clear from the fact that in the case of an electrode needle, the sharper the tip, the easier the discharge.

  The wire electrode 25 can change the distance facing the back film 12 by a length adjusting means (not shown) provided on the holding bodies 27 and 28. Specifically, the distance between the holding bodies 27 and 28 of the wire electrode 25 is adjusted according to the width dimension (for example, 1200 mm) of the bubble sheet 1 to be manufactured.

  The holding bodies 27 and 28 are supported by a support base (not shown) capable of moving up and down. Therefore, the position of the wire electrode 25 with respect to the vacuum forming roll 23 can be adjusted by adjusting the height of the support base. In this embodiment, for a vacuum forming roll 23 having a diameter of 300 mm provided with a cooling water flow path, the wire electrode 25 has a distance of about 25 mm between the surface of the wire electrode 25 and the surface of the vacuum forming roll 23. 25 is arranged. In addition, in the case of the wire electrode 25 in case a wire diameter is 0.15 mm, it is preferable that the distance with the surface of the said vacuum forming roll 23 is set to 20-30 mm. In the present embodiment, the distance L1 from the end of the vacuum forming roll 23 on the surface of the wire electrode 25 (and the virtual extension line of the opening in the back film die 22) is about 25 mm, and the surface of the wire electrode 25 The distance L2 from the height position of the axis A1 of the vacuum forming roll 23 is set to about 20 mm. That is, the wire electrode 25 is 20 mm above the height position of the axis A1 of the vacuum forming roll 23, in other words, the position where the cap film 11 and the back film 12 are bonded when no DC voltage is applied. It is arranged in.

  In addition, the wire electrode 25 of this embodiment can replace | exchange the part which faces the said back film 12 for a new wire by the sending means which is provided in the said holding bodies 27 and 28 (not shown). That is, a feeding unit is provided in one holding body 27 and a winding unit is provided in the other holding body 28, and a new portion of the wire electrode 25 is fed out from the feeding unit, and the winding unit is exposed so far. The wire electrode 25 can be wound up.

  As shown in FIG. 4, the voltage applying means 26 applies a high-voltage direct current voltage between the wire electrode 25 and the vacuum forming roll 23 to cause the back film 12 to be charged with static electricity. In this embodiment, a predetermined DC voltage is applied so that the wire electrode 25 side is positive and the vacuum forming roll 23 side is negative. Specifically, the current is 0.07 mA when the voltage is 12 kV, the current is 0.23 mA when the voltage is 15 kV, the current is 0.48 mA when the voltage is 18 kV, and the current is 1 when the voltage is 23 kV. Even when other conditions are the same as 0.02 mA, the voltage and the voltage value can be changed variously. In addition, when the shortest distance of the surface of the said wire electrode 25 whose diameter is 0.1-0.2 mm and the surface of the said back film 12 is set to 20-30 mm, the said wire electrode 25 and a vacuum forming roll The value of the direct-current voltage applied between the first and second terminals can be set to an arbitrary magnitude of 12 kV or more. If the value of the DC voltage is smaller than 12 kV, the cap film 11 and the back film 12 may not be fused completely, which may impair quality.

  In addition, the air bubble sheet manufacturing apparatus 2 of the present embodiment has the axis A2 of the nip roll 32 at a position immediately before the liner film 17 descending in the thermoplastic state contacts the cap film 11 on the nip roll 32. A wire electrode 33 arranged in parallel with the wire electrode 33, and a voltage applying means (not shown) for applying a high-voltage direct current voltage between the wire electrode 33 and the nip roll 32 to cause the liner film 17 to be charged with static electricity. A discharge device is provided.

  Since the wire electrode 33 is the same as the wire electrode 25, detailed description thereof is omitted. Further, the installation position of the wire electrode 33 with respect to the nip roll 32 and the voltage application means are the same as the installation position of the wire electrode 25 with respect to the vacuum forming roll 23 and the voltage application means 26.

  In addition, the code | symbol 29 in FIG. 3 is an air knife, and is for cooling the laminated body which consists of the cap film 11 and the back film 12. FIG. Cooling is useful for making the bubble sheet 1 transparent and achieving a high line speed. The line speed of this embodiment is set to about 45 m / min.

  The manufacturing method of the bubble sheet 1 using such a manufacturing apparatus 2 is demonstrated.

  First, a synthetic resin film in a thermoplastic state is supplied to the vacuum forming roll 23 to form the cap film 11 having a large number of protrusions 13. That is, the resin film from the first die 21 for cap film is brought into contact with the outer peripheral surface of the vacuum forming roll 23, suction is performed in the cavity 24, and the protrusion 13 corresponding to the shape of the cavity 24 is vacuum formed to form the cap film. 11 is assumed.

  Then, while the cap film 11 is on the vacuum forming roll 23, the back film 12 in a thermoplastic state is brought into contact with the protrusion 13 opening side of the cap film 11 and fused. That is, the resin film supplied from the second die 22 for the back film is opposed to the open end side of the formed projection 13 as the back film 12, and the back film 12 is brought into close contact with the cap film 11 so that both They are laminated together by heat fusion. At this time, a high voltage is applied between the wire electrode 25 and the vacuum forming roll 23 disposed immediately before the back film 12 comes into contact with the protrusion 13 of the cap film 11 and is fused. The back film 12 is charged with static electricity.

  Specifically, the discharge current discharged from the wire electrode 25 is discharged so as to draw lines of magnetic force from the entire surface of the wire electrode 25 toward the surface of the vacuum forming roll 23 as schematically shown in FIG. . In FIG. 4, the image of the discharge current is shown as a pattern. That is, since the wire electrode 25 is continuously arranged over the width direction of the bubble sheet 1, the wire electrode 25 is in a region where electric discharge is performed as compared with an electrode needle as shown in FIG. 10 formed intermittently. There is little unevenness. If it is a thing of this embodiment, the back film 12 can be melt | fused to the cap film 11 over the range for 2 rows of the protrusion 13 located in a line with the flow direction. In this manner, the back film 12 sucked by the vacuum forming roll 23 due to static electricity is brought into close contact with the protrusion 13 open side of the cap film 11.

  The cap film 11 and the back film 12 that are in close contact with each other are cooled by an air knife 29 disposed on the lower side of the vacuum forming roll 23 and then peeled off by the peeling roll 20 to form a two-layered bubble sheet. An intermediate processed product 10 is obtained.

  Thereafter, while the intermediate processed product 10 conveyed by a feed roller (not shown) is on the nip roll 32 holding the back film 12, the liner film 17 in a thermoplastic state is placed on the tip end side of the protrusion 13 of the cap film 11. Contact and fuse. That is, the resin film supplied from the third die 31 for the liner film is opposed to the tip side of the formed projection 13 as the liner film 17, and the liner film 17 is brought into close contact with the cap film 11 so that they are mutually attached. Laminate by heat sealing. At this time, a high-voltage direct current voltage is applied between the wire electrode 33 disposed immediately before the liner film 17 is brought into contact with the tip of the protrusion 13 of the cap film 11 and fused with the nip roll 32 by a voltage applying means. To apply static electricity to the liner film 17.

  Specifically, the discharge current discharged from the wire electrode 33 is discharged so as to draw lines of magnetic force from the entire surface of the wire electrode 33 toward the surface of the nip roll 32 as schematically shown in FIG. Since the wire electrode 33 is continuously arranged over the width direction of the bubble sheet 1, there is unevenness in the discharge region as compared with the electrode needle as shown in FIG. 10 that is intermittently formed. Less likely to occur. If it is a thing of this embodiment, the liner film 17 can be melt | fused to the cap film 11 over the range for 2 rows of the protrusion 13 located in a line with the flow direction. Thus, the liner film 17 attracted to the nip roll 32 by static electricity is brought into close contact with the tip end side of the protrusion 13 of the cap film 11, and the three-layered bubble sheet 1 is obtained.

  As described above, the method for manufacturing the bubble sheet 1 according to the present embodiment supplies the cap film 11 having a large number of protrusions 13 by supplying a film made of a synthetic resin in a thermoplastic state to the vacuum forming roll 23. While the cap film 11 is on the vacuum forming roll 23, it is assumed that the back film 12 in the thermoplastic state is brought into contact with the projection 13 open side of the cap film 11 and fused. . And this manufacturing method is a voltage application means between the wire electrode 25 and the said vacuum forming roll 23 arrange | positioned in the position just before the back film 12 contacts and fuse | melts the protrusion 13 open | release side of the cap film 11. The back film 12 was charged with static electricity by applying a high direct-current voltage by 26, and the back film 12 was attracted to the vacuum forming roll 23 by static electricity so as to be in close contact with the protrusion 13 open side of the cap film 11.

  Therefore, it is possible to solve the problems of temperature management and pressure management that are conventionally caused when laminating a plurality of films with a pressure roll, and also to solve the problem of sparks when an electrode needle is conventionally used. be able to. That is, by using the wire electrode 25, stable discharge without unevenness can be performed. In addition, no scorching due to spark occurs, and the cap film 11 and the back film 12 can be bonded together reliably. Therefore, the quality of the product can be improved as compared with the conventional one.

  Furthermore, the manufacturing method of the bubble sheet 1 according to the present embodiment includes an intermediate processed product 10 including a cap film 11 having a large number of protrusions 13 and a back film 12 attached to the cap film 11 on the opening side of the protrusions 13. It is assumed that the liner film 17 in a thermoplastic state is brought into contact with the tip end side of the projection 13 of the cap film 11 and is fused while the nip roll 32 is on the nip roll 32. Then, a high-voltage DC voltage is applied between the wire electrode 33 disposed immediately before the liner film 17 is brought into contact with the tip of the protrusion 13 of the cap film 11 and fused with the nip roll 32 by a voltage applying means. The liner film 17 was charged with static electricity, and the liner film 17 was attracted to the nip roll 32 by static electricity so as to be in close contact with the tip end side of the protrusion 13 of the cap film 11.

  Therefore, it is possible to solve the problems of temperature management and pressure management that are conventionally caused when a plurality of films are bonded together by nip rolls, and to solve the problem of sparks when using electrode needles conventionally. it can. That is, by using the wire electrode 33, stable discharge without unevenness can be performed. Further, no scorching due to spark occurs, and the cap film 11 and the liner film 17 can be reliably bonded to each other. Therefore, the quality of the product can be improved as compared with the conventional one.

  Since the wire electrodes 25 and 33 have an adjustment function capable of changing the distances facing the back film 12 and the liner film 17 respectively, the wire electrode 25 is adapted to the width of the roll of the bubble sheet 1 to be manufactured. , 33 can be easily changed. In the conventional electrode needle, it is necessary to prepare another discharge base and electrode needle in order to cope with such a change in length.

  In the present embodiment, when the shortest distance between the surfaces of the wire electrodes 25 and 33 having a diameter of 0.15 mm and the surfaces of the back film 12 and the liner film 17 is set to about 20 mm, The value of the DC voltage applied between the wire electrode 25 and the vacuum forming roll 23 and the nip roll 32 can be set to an arbitrary magnitude of 12 kV or more. In conventional electrode needles, in order to properly fuse the back film to the cap film, the distance between the electrode needle and the vacuum forming roll is selected, and trial and error is performed according to the characteristics of the synthetic resin and the thickness of the back film. The selection of the value of the DC voltage to be applied determined by the method is important. That is, in the case of the electrode needle, it is necessary to accurately determine the value of the direct current voltage with respect to the distance between the electrode needle and the vacuum forming roll. However, with the wire electrodes 25 and 33 as in the present embodiment, the voltage / current value can be freely set, and even if the voltage / current value is lower than the voltage / current value applied in the case of the electrode needle, The back film 12 and the liner film 17 can be appropriately fused to the cap film 11. Furthermore, the spark which generate | occur | produces around the wire electrodes 25 and 33 can also be suppressed by making voltage / current value low.

  Further, the manufacturing apparatus 2 of the present embodiment supplies a film made of synthetic resin in a thermoplastic state to the vacuum forming roll 23 to form a cap film 11 having a large number of protrusions 13. The bubble sheet 1 is manufactured by bringing the back film 12 in the thermoplastic state while being on the vacuum forming roll 23 into contact with the projection 13 opening side of the cap film 11 and fusing it. And this manufacturing apparatus 2 is parallel to the axial center A1 of the said vacuum forming roll 23 in the position just before the back film 12 which descend | falls in a thermoplastic state contacts the cap film 11 on the vacuum forming roll 23. A wire electrode 25 arranged and a voltage applying means 26 for applying a high direct current voltage between the wire electrode 25 and the vacuum forming roll 23 to cause the back film 12 to be charged with static electricity were provided.

  If it is such, not only can the generation of sparks be suppressed as compared with the one using electrode needles, but the apparatus 2 can be made compact, and the attaching and removing operations are relatively easy. be able to.

  Further, since the pressure roll that has been conventionally used for fusing the back film is no longer necessary, the back film 12 that is in close contact with the cap film 11 can be easily cooled with the air knife 29, and thereby the back film. It became possible to increase the transparency of 12.

  Further, in the manufacturing apparatus 2 of the present embodiment, the intermediate processed product 10 including the cap film 11 having a large number of protrusions 13 and the back film 12 attached to the opening side of the protrusions 13 of the cap film 11 is placed on the nip roll 32. The bubble sheet 1 is manufactured by bringing the liner film 17 in the thermoplastic state into contact with the tip end side of the projection 13 of the cap film 11 and fusing it, and is lowered in the thermoplastic state. A wire electrode 33 disposed parallel to the axis A2 of the nip roll 32 at a position immediately before the incoming liner film 17 contacts the cap film 11 on the nip roll 32, and between the wire electrode 33 and the nip roll 32. Voltage applying means for applying a high direct current voltage to the liner film 17 to cause static electricity. Since girder, it is possible to suppress the occurrence of sparks as compared with one using a needle electrode.

  Furthermore, in the bubble sheet 1 of the present embodiment, a large number of streak-like bubbles 15 are formed between the flat film 16 where the projections 13 are not formed on the cap film 11 and the back film 12. The size of the bubble 15 is a length dimension of 1.3 to 1.4 mm or less and a width dimension of 0.4 to 0.5 mm or less.

  That is, if it is like this embodiment, without pressing the back film 12 against the cap film 11 and reducing the air entering the adhesive surface between the cap film 11 and the back film 12 as much as possible. The size of each streaky bubble 15 can be made smaller than that of the electrode needle. In other words, since the generation of relatively large streak bubbles generated in the case of the electrode needle can be suppressed, the appearance of the bubble sheet 1 can be improved. In the case of the method using a conventional pressure roll, the back film is mechanically crushed by the pressure roll, so there is little room for air bubbles to enter between the flat portion of the cap film and the back film, There was no problem of generation of streak bubbles.

  Moreover, since the air bubble sheet 1 of this embodiment makes the back film 12 and the liner film 17 contact the cap film 11 by static electricity, even at a relatively high operation speed, the transparency is high and the width direction is low. The air bubble sheet 1 in which the shrinkage is suppressed can be obtained.

  The present invention is not limited to the embodiment described above.

  For example, the bubble sheet is not limited to a three-layer structure, and may have a two-layer structure including a cap film and a back film. In particular, in the case of a bubble sheet having a two-layer structure, streak bubbles are more conspicuous than those in a three-layer structure, and therefore it is preferable that each streak bubble is as small as possible.

  In the case of a three-layer structure, the method and apparatus for producing a bubble sheet of the present invention is applied in at least one of the production steps of adhesion between a cap film and a back film and adhesion between a cap film and a liner film. If it is.

  In the production, any additive such as a colorant, a filler, an antioxidant, an antistatic agent, an antibacterial agent, and a combustion auxiliary agent may be added to the foam sheet.

  The shape of the bubbles (protrusions) is not limited to a cylindrical shape, and can be variously changed. Further, the arrangement of the bubbles (projections) is not limited to the staggered arrangement, and can be variously changed.

  The value of the DC voltage to be applied and the distance between the electrode wire and the vacuum forming roll or nip roll are appropriately selected according to the characteristics of the plastic used for the back film or liner film and the thickness of the back film or liner film. That's fine. The direction in which the high-voltage DC voltage is applied is selected according to the type of plastic constituting the back film or liner film. The choice depends on whether the plastic is easily charged positively or negatively when placed in a high-voltage DC electric field. In the former case, the vacuum forming roll or nip roll is added, and the wire electrode is set. In the latter case, the wire electrode is positive and the vacuum forming roll or nip 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.

  The wire electrode may be one that can be automatically wound by the winding unit while automatically feeding a new portion of the wire electrode from the feeding unit. For example, various settings can be made, such as sending a wire electrode for a predetermined distance every predetermined time set, or always sending a wire electrode for a predetermined distance. If it is such, the cleaning of the wire electrode which the powder falling from a back film tends to adhere becomes unnecessary.

  In addition, the method of manufacturing the cap film is not limited to the so-called “direct method” in which the film melt-extruded from the die is supplied to the vacuum forming roll while it is in a plasticized state. You may employ | adopt what is called a "reheating method" which heats by a means, such as making it contact with a heating roll while reaching a forming roll, and supplies as a plasticization state. If it is manufactured by the reheating method, it is possible to manufacture a product that is firmer than that manufactured by the direct method.

  In addition, various changes may be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Bubble sheet 10 ... Intermediate processed product 11 ... Cap film 12 ... Back film 13 ... Protrusion 15 ... Streaky bubble 16 ... Flat part 17 ... Liner film 2 ... Manufacturing apparatus 23 ... Vacuum forming roll 25 ... Wire electrode 26 ... Voltage application Means 32 ... Nip roll 33 ... Wire electrode

Claims (4)

While an intermediate processed product having a cap film having a large number of protrusions and a back film attached to the protrusion opening side of the cap film is on the nip roll, a liner film in a thermoplastic state is placed on the cap film. It is a method of manufacturing a bubble sheet by bringing it into contact with the tip end side of a protrusion and fusing it,
Static electricity is applied to the liner film by applying a high-voltage DC voltage by a voltage applying means between the wire electrode disposed immediately before the liner film comes into contact with the tip end of the cap film and is fused. A method for producing a bubble sheet, characterized in that the liner film is attracted to the nip roll by static electricity and is brought into close contact with the tip end side of the protrusion of the cap film. The method for producing a bubble sheet according to claim 1, wherein the distance between the wire electrode and the liner film can be changed by a length adjusting means. When the shortest distance between the surface of the wire electrode having a diameter of 0.1 to 0.2 mm and the liner film is set to 20 to 30 mm, the DC voltage applied between the wire electrode and the nip roll The manufacturing method of the bubble sheet of Claim 1 or 2 which can set a value to the arbitrary magnitude | sizes of 12 kV or more. While an intermediate processed product having a cap film having a large number of protrusions and a back film attached to the protrusion opening side of the cap film is on the nip roll, a liner film in a thermoplastic state is placed on the cap film. An apparatus for producing a bubble sheet by bringing it into contact with the tip end of the protrusion and fusing it,
A wire electrode disposed in parallel with the axis of the nip roll at a position immediately before the liner film descending in the thermoplastic state contacts and melts in contact with the protrusion tip side of the cap film on the nip roll, and the wire A voltage applying means is provided between the electrode and the nip roll to apply a high-voltage DC voltage to cause the liner film to be charged with static electricity . The liner film is attracted to the nip roll by static electricity and is placed on the tip end side of the cap film protrusion. An apparatus for producing a bubble sheet, characterized in that it is in close contact .

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