JP4967623B2 - Method for producing synthetic resin foam sheet - Google Patents

Description

  The present invention relates to a method for producing a synthetic resin air bubble sheet that produces a synthetic resin air bubble sheet in which a large number of gas bubbles sealed with gas are formed.

Conventionally, a synthetic resin sheet melted on a molding roll having a large number of recesses formed on the outer peripheral surface thereof is vacuum-formed to produce a first sheet on which a large number of protrusions are formed. A method of manufacturing a synthetic resin air bubble sheet by pressure bonding a second sheet is known (for example, see Patent Document 1).
JP-A-11-216770

  However, in the air bubble sheet, it is desired that the two sheets are firmly fused and joined, but the fusing condition of these sheets has been adjusted based on the experience of the operator. For this reason, it is conceivable that individual differences among workers affect the fused state of the bubble sheet.

  An object of this invention is to provide the manufacturing method of the bubble sheet made from a synthetic resin which can improve the melt | fusion property of a bubble sheet in view of the said point.

In order to achieve the above object, the present invention supplies the first sheet (11) having a melting point or higher to the forming roll (22) having a recess (22a) corresponding to the protrusion (11a) on the outer peripheral surface. A first sheet supplying step, a protrusion forming step of forming a protrusion (11a) on the first sheet (11) on the outer peripheral surface of the forming roll (22), and a protrusion (11a) of the first sheet (11). ) On the opening-side surface, a second sheet supplying step for supplying the second sheet (12) heated to the melting point or higher, and a first portion in which the protrusion (11a) is formed with respect to the second sheet (12). A joining step of joining the second sheet (12) and the first sheet (11) by applying an external force in a direction pressed against the sheet (11) for a predetermined period, and the first sheet before the predetermined period in the joining step ends. (11) and second sheet (12) And a cooling step of cooling below the melting point,
In a joining process, in the direction pressed against the 1st sheet (11) with respect to the 2nd sheet (12) using pressurization roll (23) arranged so that a forming roll (22) and outer peripheral surfaces may contact. Apply external force,
In the cooling process, the compressed air supply device (25), characterized that you supply compressed air for cooling to the second sheet (12) side bonded first sheet (11) in the second sheet (12) It is said.

As described above, in the joining step, the first sheet (11) and the second sheet (the second sheet (12)) until the predetermined period in which the external force is applied to the second sheet (12) in the direction of pressing the first sheet (11) is completed. By cooling 12) below the melting point, the first sheet (11) and the second sheet (12) can be firmly bonded without causing poor fusion.
In the cooling step, the compressed air supply device (25) supplies the compressed air for cooling to the bubble sheet (10), whereby the temperature of the bubble sheet (10) can be efficiently lowered to the melting point or lower. .

Further, in the bonding step, by providing the elastic member (23a) on the outer peripheral surface of the pressure roll (23), it can increase the contact area between the forming roll (22) and pressure roll (23), the pressure roll ( The pressurization time by 23) can be lengthened, and the joining state of a 1st sheet | seat (11) and a 2nd sheet | seat (12) can be improved.

  The elastic member (23a) has a thickness of 1.5 to 10% of the diameter of the pressure roll (23) and has a rubber hardness (JIS hardness A) in the range of 50 to 110 degrees. Thus, the contact area between the forming roll (22) and the pressure roll (23) can be increased while securing the pressure applied by the pressure roll (23).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of a synthetic resin air bubble sheet 10 showing an embodiment of the present invention. As shown in FIG. 1, the bubble sheet 10 of this embodiment is comprised from the 1st sheet | seat (cap film) 11 in which many protrusion parts 11a were formed, and the flat 2nd sheet | seat (back film) 12. As shown in FIG. It has a two-layer structure. In the first sheet 11 of the present embodiment, a large number of cylindrical protrusions 11 a are embossed, and a flat second sheet 12 is joined to the protrusion opening side of the first sheet 11. Thereby, between the 1st sheet | seat 11 and the 2nd sheet | seat 12, the bubble part 13 by which air was sealed was formed.

In the present embodiment, a polyolefin resin such as polyethylene or polypropylene is used as the synthetic resin constituting the bubble sheet 10, and it is desirable to use polyethylene when used for applications that require flexibility. In addition, the synthetic resin air bubble sheet 10 desirably has a weight per unit area (weight per unit area) of 35 to 200 g / m ² when the application requires flexibility such as a packaging material.

  FIG. 2 shows an example of the main components of the bubble sheet manufacturing apparatus for manufacturing the bubble sheet 10 of the present embodiment. As shown in FIG. 2, the bubble sheet manufacturing apparatus is provided with two sheet supply units 20 and 21 for supplying a synthetic resin sheet. The flat first sheet 11 before the protrusion 11 a is formed is supplied from the first sheet supply unit 20, and the flat second sheet 12 is supplied from the second sheet supply unit 21. Each of these sheet supply units 20 and 21 is composed of a flat die connected to an extruder (not shown). The bubble sheet manufacturing apparatus is provided with a forming roll 22, a pressure roll 23, and a peeling roll 24. The rolls 22, 23, 24 of this embodiment are made of iron. These rolls 22, 23, and 24 are cylindrical, and the axial direction is arrange | positioned in parallel. These rolls 22, 23, and 24 are each configured to be rotationally driven by a driving device (not shown).

  A large number of recesses 22 a corresponding to the bubble portions 13 of the bubble sheet 10 are formed on the outer peripheral surface of the forming roll 22. The bottom of the recess 22a of the forming roll 22 is connected to a vacuum pump (not shown), and vacuum suction is possible with the recess 22a. The forming roll 22 is configured to rotate counterclockwise in FIG.

  The pressure roll 23 is disposed so that the forming roll 22 and the outer peripheral surface are in contact with each other, and the outer peripheral surface of the pressure roll 23 is pressed against the outer peripheral surface of the forming roll 22. In this way, the forming roll 22 applies an external force in a direction in which the forming roll 22 is pressed against the first sheet 11 against the second sheet 12. The pressure roll 23 is configured to rotate clockwise in FIG.

  An elastic member 23a such as rubber is provided on the outer peripheral surface of the pressure roll 23 of the present embodiment. The area of the elastic member 23a that contacts the forming roll 22 is elastically deformed, so that the contact area between the forming roll 22 and the pressure roll 23 can be increased.

  If the elastic member 23a is too thick, the applied pressure becomes low, and if it is too thin, the contact area becomes small. For this reason, in order to increase the contact area while ensuring the pressure applied by the pressure roll 23, the thickness of the elastic member 23 a is set within a range of 1.5 to 10% of the diameter of the pressure roll 23. As the diameter of the pressure roll 23 increases, the specific heat increases, and once the temperature rises, it becomes difficult to cool. Therefore, as the diameter of the pressure roll 23 increases, the elastic member 23a is thickened and the heat of the bubble sheet 10 is applied. It is desirable to make it difficult to convey to the pressure roll 23.

  Further, when the hardness of the elastic member 23a is too low, the applied pressure becomes low, and when the hardness is too high, the contact area becomes small. For this reason, in order to increase the contact area while ensuring the pressure applied by the pressure roll 23, the rubber hardness (Hs) of the elastic member 23a is set in the range of 50 to 110 degrees. This rubber hardness is based on the JIS-A standard. When the elastic member 23a is thick, the applied pressure tends to decrease. Therefore, it is desirable to reduce the rubber hardness. When the elastic member 23a is thin, the contact area tends to decrease. It is desirable to enlarge it.

  On the outer peripheral surface of the forming roll 22, there are provided a protrusion forming area A for forming the protrusion 11 a on the first sheet 11 and a fusion area B for bonding the second sheet 12 to the first sheet 11 on which the protrusion is formed. It has been. The projection forming area A is an area where the first sheet 11 supplied from the first sheet supply unit 20 is in contact with the pressure roll 23 on the outer peripheral surface of the forming roll 22. The fusion region B is a region where the pressure roll 23 is in contact with the outer peripheral surface of the forming roll 22.

  Vacuum suction is performed in the projection forming area A of the forming roll 22, and formation of the uneven shape on the first sheet 11 is completed within a period in which the first sheet 11 passes through the projection forming area A. In the fusion region B of the forming roll 22, vacuum suction is not performed, and the first sheet 11 and the second sheet 12 are fused by pressing with the pressure roll 12, and the first sheet 11 and the second sheet are bonded. These fusions are completed within a period in which 12 passes through the fusion region B.

  The peeling roll 24 is for peeling the bubble sheet 10 from the outer peripheral surface of the forming roll 22, and is provided on the opposite side of the pressure roll 22 with the forming roll 22 as the center. The peeling roll 24 is configured to rotate clockwise in FIG. Although not shown, a take-up roll for taking up the bubble sheet 10 is provided downstream of the peeling roll 24 in the sheet flow.

  The air bubble sheet manufacturing apparatus is provided with a compressed air supply device 25 for cooling the air bubble sheet 10 fused in the fusion region B of the forming roll 22. The compressed air supply device 25 is configured to supply compressed air for cooling from the downstream side in the sheet flow direction to the contact portion between the forming roll 22 and the pressure roll 23 to cool the bubble sheet 10. For this reason, the compressed air supply device 25 is configured to supply compressed air to the second sheet 12 side of the bubble sheet 10.

Next, the manufacturing method of the bubble sheet 10 of this embodiment is demonstrated. First, the first sheet 11 before the formation of the protrusion having a melting point or higher is supplied from the first sheet supply unit 20 to the outer peripheral surface of the forming roll 22 (first sheet supply step). The first sheet 11 is supplied to the projection forming area A in the forming roll 22. The first sheet 11 moves as the forming roll 22 rotates. The first sheet 11 having a melting point or higher is vacuum-sucked by the concave portion 22a of the projection forming area A, whereby a large number of projection portions 11a constituting the bubble portion 13 are formed (projection portion forming step).
The temperature of the first sheet 11 is slightly lowered by contacting the outer peripheral surface of the forming roll 22 in the projection forming region A of the forming roll 22. At this time, in the first sheet 11, the temperature of the protrusion 11 a that contacts the recess 22 a is lower than that of the sheet surface that contacts the outer peripheral surface of the forming roll 22, so the first sheet 11 that contacts the outer peripheral surface of the forming roll 22. The molten state is maintained on the sheet surface. The first sheet 11 on which the protrusion 11 a is formed moves to the fusion region B of the forming roll 22 and is supplied between the forming roll 22 and the pressure roll 23.

  Next, the second sheet 12 having a melting point or higher is supplied from the second sheet supply unit 21 between the forming roll 22 and the pressure roll 23 (second sheet supply step). Thereby, in the fusion | melting area | region B of the forming roll 22, the 2nd sheet | seat 12 and the 1st sheet | seat 11 are fuse | melted and joined because the 2nd sheet | seat 12 is pressed against the 1st sheet | seat 11 by the pressure roll 23. (Joining process). At this time, since the elastic member 23 a is provided on the outer peripheral surface of the pressure roll 23, the contact area between the pressure roll 23 and the forming roll 22 is large, and the pressurization time by the pressure roll 23 is sufficient. Can be secured. Thereby, the joining state of the 1st sheet | seat 11 and the 2nd sheet | seat 12 can be improved.

  Further, since the compressed air is supplied from the compressed air supply device 25 to the contact portion between the pressure roll 23 and the forming roll 22, the bubble sheet 10 is cooled by air and the temperature is lowered (cooling step). Since the compressed air is blown to the second sheet 12 side of the bubble sheet 10, the second sheet 12 having a higher temperature than the first sheet 11 is preferentially cooled. Further, the second sheet 12 is cooled by contacting the outer peripheral surface of the pressure roll 23. Thereby, the bubble sheet 10 is cooled to below the melting point before leaving the fusion region B of the forming roll 22. That is, after the bubble sheet 10 is cooled to the melting point or lower, the stress by the pressure roll 23 is released.

  The bubble sheet 10 cooled to below the melting point moves with the rotation of the forming roll 22, changes its traveling direction with the peeling roll 24, and is peeled off from the outer peripheral surface of the forming roll 22. Thereby, the 1st sheet | seat 11 and the 2nd sheet | seat 12 are melt | fused and joined, and the bubble sheet | seat 10 in which gas was enclosed with the bubble part 13 is shape | molded.

  As described above, the first sheet 11 and the second sheet 12 cause poor fusion by cooling the bubble sheet 10 to the melting point or less before the bubble sheet 10 leaves the fusion region B of the forming roll 22. These can be joined firmly. That is, it is considered that the first sheet 11 and the second sheet 12 are easily peeled in the state of the melting point or higher, and when the stress by the pressure roll 23 is released before the bubble sheet 10 is cooled to the melting point or lower, It is thought that the poor fusion which the 1 sheet 11 and the 2nd sheet | seat 12 peel will generate | occur | produce easily. For this reason, the first sheet 11 and the second sheet 12 are released when the stress is released by releasing the stress by the pressure roll 23 after the bubble sheet 10 is cooled to the melting point or lower as in the present embodiment. Is already firmly joined, the first sheet 11 and the second sheet 12 can be appropriately fused.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. Only the parts different from the first embodiment will be described below.

  FIG. 3 shows the main components of the bubble sheet manufacturing apparatus of the second embodiment. As shown in FIG. 3, the air bubble sheet manufacturing apparatus of the second embodiment is provided with a cooling roll 26. The cooling roll 26 is of a water-cooling type, and is arranged so that the pressure roll 23 and the outer peripheral surfaces are in contact with each other. When the cooling roll 26 comes into contact with the outer peripheral surface of the pressure roll 23, the elastic member 23 a of the pressure roll 23 is cooled. For this reason, when the 2nd sheet | seat 12 contacts the outer peripheral surface of the pressurization roll 23, temperature can be lowered more and the cooling effect of the 2nd sheet | seat 12 by the pressurization roll 23 can be improved. Thereby, the bubble sheet 10 can be reliably cooled below the melting point within a period in which the first sheet 11 and the second sheet 12 pass through the fusion region B.

(Third embodiment)
Next, a third embodiment of the present invention will be described. Only the parts different from the first embodiment will be described below.

  FIG. 4 shows the main components of the bubble sheet manufacturing apparatus of the third embodiment. As shown in FIG. 4, the pressure roll 23 is not provided in the bubble sheet manufacturing apparatus of the third embodiment. And the rotational speed of the peeling roll 24 located in the sheet | seat flow direction downstream of the shaping | molding roll 22 is high, and the rotation speed of the foaming sheet 22 of the bubble sheet 10 by rotation of the peeling roll 24 is higher than the moving speed of the bubble sheet 10 by rotation of the shaping | molding roll 22. The moving speed (take-off speed) is configured to be larger. That is, the movement amount (take-off amount) of the bubble sheet 10 due to the rotation of the peeling roll 24 is configured to be larger than the movement amount of the bubble sheet 10 due to the rotation of the forming roll 22. In the present embodiment, the moving speed of the bubble sheet 10 by the peeling roll 24 is increased within a range of 1 to 5% with respect to the moving speed of the bubble sheet 10 by the forming roll 22.

  In this way, the bubble sheet 10 is pulled by the peeling roll 24 because the moving speed of the bubble sheet 10 in the downstream peeling roll 24 is faster than the moving speed of the bubble sheet 10 in the molding roll 22. It is pressed against the outer peripheral surface of the forming roll 22 with a predetermined tension. Thereby, the second sheet 12 positioned on the outer side of the bubble sheet 10 is pressed against the first sheet 11 positioned on the inner side, and an external force is applied to the second sheet 12 in a direction pressing the first sheet 11. Become. Note that the peeling roll 24 of the present embodiment corresponds to the sheet take-up means of the present invention.

  For this reason, in the present embodiment, the first sheet 11 and the second sheet 12 are in contact with each other on the outer peripheral surface of the forming roll 22, and the region until the bubble sheet 10 is peeled off by the peeling roll 24 is melted. It is a landing area B. For this reason, in the compressed air supply device 25 of the present embodiment, after the first sheet 11 and the second sheet 12 start to contact, the air bubble sheet 10 in which the first sheet 11 and the second sheet 12 are joined is separated from the peeling roll 24. The bubble sheet 10 is cooled to below the melting point within a period until it is peeled from the forming roll 22 by the above.

  Even with the configuration of the bubble sheet manufacturing apparatus described above, the bubble sheet 10 can be manufactured, and by omitting the pressure roll 23, the configuration of the bubble sheet manufacturing apparatus can be simplified. Moreover, according to the structure of this embodiment, the quality of the bubble sheet 10 manufactured so that it may demonstrate below can be improved.

  FIG. 5 is a cross-sectional view of the bubble sheet 10, (a) shows the bubble sheet 10 manufactured by the bubble sheet manufacturing apparatus of the third embodiment, and (b) shows the first and second embodiments for comparison. The bubble sheet 10 manufactured with the manufacturing apparatus of the form is shown.

  As shown in FIGS. 5A and 5B, the first sheet 11 has a portion corresponding to the bubble portion 13 that is stretched by vacuum forming with the forming roll 22, and thus the bubble portion 13 in the first sheet 11. The thickness of the part corresponding to is thinner than other parts. Further, as shown in FIG. 5B, in the configuration of the first and second embodiments, the thickness of the second sheet 12 is not uniform, but as shown in FIG. In the configuration of the third embodiment, the thickness of the second sheet 12 is uniform.

  That is, in the configuration of the first and second embodiments using the pressure roll 23, the second sheet 12 is pressed against the first sheet 11 by the pressure roll 23 (from the bottom to the top in FIG. 5B). External force acts in the direction of heading. At this time, since the synthetic resin heated above the melting point has fluidity, when the second sheet 12 is pressed against the first sheet 11, it becomes a cavity corresponding to the bubble portion 13 in the second sheet 12. Synthetic resin around the periphery wraps around the site. As a result, the thickness of the portion corresponding to the bubble portion 13 in the second sheet 12 is increased, and the thickness of the peripheral portion is decreased. As a result, the thickness of the second sheet 12 becomes uneven.

  On the other hand, in the configuration of the third embodiment in which the pressure sheet 23 is not provided and the bubble sheet 10 is pulled by the peeling roll 24 and pressed against the outer peripheral surface of the forming roll 22 as in the present embodiment, External force acts in the direction of pulling in the surface direction (left-right direction in FIG. 5A). For this reason, the synthetic resin does not wrap around at the portion corresponding to the bubble portion 13 in the second sheet 12 as shown in FIG. 5B, and the thickness of the second sheet 12 becomes uniform.

  In the case of the configuration using the pressure roll 23, the outer peripheral surface of the pressure roll 23 is transferred to the surface of the second sheet 12 by pressing the outer peripheral surface of the pressure roll 23 against the second sheet 12. The beauty of the bubble sheet 10 is impaired. On the other hand, according to the configuration in which the pressure roll 23 is not used as in the present embodiment, the outer peripheral surface of the pressure roll 23 is not transferred to the surface of the second sheet 12, and the aesthetic appearance of the bubble sheet 10 is improved. Can be improved.

(Other embodiments)
In each of the above embodiments, the example in which the present invention is applied to the two-layered bubble sheet 10 including the first sheet 11 and the second sheet 12 has been described. However, the present invention is not limited to this. It is also possible to apply to a three-layer product in which a flat sheet is bonded to the surface of the first sheet 11 opposite to the surface where the second sheet 12 is bonded.

  In the third embodiment, the rotational speed of the peeling roll 24 positioned downstream in the sheet flow direction is increased by the forming roll 22, so that the air bubble sheet 10 is taken up from the moving speed of the air bubble sheet 10 on the forming roll 22. Although the speed has been increased, the present invention is not limited to this, and the movement of the bubble sheet 10 in the forming roll 22 is increased by increasing the rotational speed of a take-up roll (not shown) located downstream of the peeling roll 24 in the sheet flow direction. The take-up speed of the bubble sheet 10 may be increased from the speed.

It is a perspective view of the air bubble sheet concerning each embodiment. It is a conceptual diagram of the bubble sheet manufacturing apparatus of 1st Embodiment. It is a conceptual diagram of the bubble sheet manufacturing apparatus of 2nd Embodiment. It is a conceptual diagram of the bubble sheet manufacturing apparatus of 3rd Embodiment. It is sectional drawing of a bubble sheet.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Bubble sheet, 11 ... 1st sheet (uneven | corrugated sheet), 12 ... 2nd sheet (flat sheet), 13 ... Bubble part, 20 ... 1st sheet supply part, 21 ... 2nd sheet supply part, 22 ... A forming roll, 23 ... a pressure roll, 23a ... an elastic member, 24 ... a peeling roll, 25 ... a compressed air supply device, 26 ... a cooling roll.

Claims (3)

A bubble in which a first sheet (11) made of synthetic resin on which a large number of protrusions (11a) are formed and a second sheet (12) made of synthetic resin that is flat are joined and the gas is sealed. It is a manufacturing method of the synthetic resin air bubble sheet in which the part (13) is formed,
A first sheet supply step of supplying the first sheet (11) having a melting point or higher to a forming roll (22) having a recess (22a) corresponding to the protrusion (11a) on the outer peripheral surface;
A protrusion forming step of forming the protrusion (11a) on the first sheet (11) on the outer peripheral surface of the forming roll (22);
A second sheet supplying step of supplying the second sheet (12) heated to a melting point or higher to the opening side surface of the protrusion (11a) in the first sheet (11);
An external force is applied to the second sheet (12) for a predetermined period in a direction in which the protrusion (11a) is pressed against the first sheet (11), and the second sheet (12) and the first sheet (12). A joining step of joining the sheet (11);
A cooling step of cooling the first sheet (11) and the second sheet (12) to a melting point or lower before the predetermined period in the joining step ends ,
In the joining step, the first sheet (11) with respect to the second sheet (12) using the pressure roll (23) arranged so that the forming roll (22) and the outer peripheral surfaces are in contact with each other. Apply external force in the direction to press against
In the cooling step, the compressed air supply device (25) supplies compressed air for cooling to the second sheet (12) side of the joined first sheet (11) and second sheet (12). A method for producing a synthetic resin air bubble sheet. The method for producing a synthetic resin foam sheet according to claim 1 , wherein an elastic member (23a) is provided on an outer peripheral surface of the pressure roll (23). The elastic member (23a) has a thickness of 1.5 to 10% of the diameter of the pressure roll (23) and has a rubber hardness (JIS hardness A) in the range of 50 to 110 degrees. The method for producing a synthetic resin foam sheet according to claim 2 .

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