JP2015016616A - Foam sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam sheet which has easy cutting properties in its width direction without impairing cushioning performance and transparency.SOLUTION: A long sheet-shaped foam sheet 1 includes a cap film 11 having cap-shaped projections 13 and a back film 12 loaded on the open sides of the projections. The foam sheet 1 has easy cutting properties in its width direction orthogonal to a flow direction by adding a cyclic olefin copolymer in an amount of 10-50% to the back film 12.

Description

  The present invention relates to a bubble sheet used for a cushioning material or the like.

  Conventionally, when using an air bubble sheet as a cushioning material or the like, a user who does not have a predetermined amount of the air bubble sheet purchased in advance purchases the air bubble sheet wound in a roll shape, feeds it to an arbitrary length, and cuts it out. I was using. A polyolefin film has been used as a material for the bubble sheet. Conventional bubble sheets are oriented in the flow direction and have poor straight cut ability in the width direction. For this reason, when cutting the required amount of the bubble sheet in the width direction, it is necessary to use a special tool such as a scissors.

  Therefore, in order to improve the rectilinear cutting property in the width direction of the bubble sheet, a technique is also disclosed in which perforation is put in the bubble sheet in advance so as to be easily cut in the width direction (see, for example, Patent Document 1). However, if a perforation is made in the bubble sheet, a hole is opened in the bubble that overlaps with the place, and the air escapes, leading to a problem that the buffering capacity is reduced. For this reason, if the buffering capacity is to be secured, the intervals in the flow direction of the perforations that are provided in advance cannot be made close, and there is a problem in that there are no perforations at arbitrary positions of the user.

  In addition, a technique of laminating a high-density polyethylene film stretched in the transverse direction in order to improve the straight-cut property in the width direction is also disclosed (see, for example, Patent Document 2). According to such a technique, it is possible to cut in the width direction at an arbitrary position in the flow direction, but there is a problem that the transparency of the bubble sheet is lowered by laminating the high-density polyethylene film. However, in the bubble sheet having such a structure, there is a seam due to switching of the high-density polyethylene film in the flow direction. In the portion corresponding to the joint, there is a portion where the straight-cut property in the width direction is low as in the conventional case, that is, the user cannot cut in the width direction by hand. Further, in such a bubble sheet, there is a risk that the cut property at such a part is impaired by forming a part laminated with wrinkles in the laminate material.

JP 2011-255922 A Japanese Patent No. 389976

  This invention pays attention to such a malfunction, and it aims at providing the bubble sheet provided with the easy-cut property of the width direction, without impairing buffer performance and transparency.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the bubble sheet according to the present invention is a bubble sheet formed into a long sheet shape including a cap film having a cap-shaped protrusion and a back film attached to the open side of the protrusion, It is characterized by having an easy-cut property in the width direction perpendicular to the flow direction by adding 10 to 50% of the cyclic olefin copolymer to one layer.

  Here, the bubble sheet of the present invention may have a two-layer structure or a three-layer structure or a multilayer structure.

  If this is the case, the perforations on the air bubble sheet may be reduced to reduce the buffering capacity, and a special layer may be coated to reduce the transparency or make the structure complicated. However, it is possible to effectively improve the straight cut in the width direction, that is, ease of hand cutting for the user. That is, according to the present invention, it is possible to provide a bubble sheet having easy-cutting in the width direction without impairing the buffer performance and transparency.

  And it is desirable for such a bubble sheet to maintain the bubble strength effectively and maintain the buffer capacity effectively while maintaining the straight cut in the width direction. For that purpose, it is desirable that the cap film having the thinnest part of the normal bubble sheet film does not include the cyclic olefin copolymer, and only the layers other than the cap film such as the back film and the liner film include the cyclic olefin copolymer. .

  That is, as an example of a specific embodiment of the bubble sheet having the above-described features, it has a two-layer structure including the cap film and the back film, and the cyclic olefin copolymer is 10 to 50% in the back film. In addition, 50% to 90% of low density polyethylene having a MFR (melt flow rate) value of 2 to 15 is blended, and the cap film does not contain the cyclic olefin copolymer.

  In the case where the cap film, the back film and the liner film have a three-layer structure, the cyclic olefin copolymer is 10 to 50% in one or both of the back film and the liner film, and An example in which 50 to 90% of low density polyethylene having an MFR value of 2 to 15 is blended and the cap olefin copolymer is not included in the cap film can be mentioned.

  The reason why each of the above-described embodiments is desirable is that when the cyclic olefin copolymer and the low density polyethylene are blended, the straight cut property is improved, but on the other hand, the film becomes brittle.

  Further, if the MFR of the base material of each film constituting the bubble sheet is low, stringing at the time of tearing becomes large. Therefore, as described above, it is preferable that 50 to 90% of low density polyethylene of MFR 2 to 15 is blended. In addition, this can reduce resistance due to elongation at the time of tearing, and can prevent the end surface from curling due to the elongation of the end surface after tearing.

  In order to further improve the straight-cut property in the width direction more effectively, it is preferable that a notch is formed at the edge in the width direction. Here, the “notch” may be intermittently provided in the width direction, or may be provided with a plurality of notches by forming an edge in the width direction in a sawtooth shape, for example.

  ADVANTAGE OF THE INVENTION According to this invention, the bubble sheet provided with the easy-cut property of the width direction can be provided, without impairing buffer performance or transparency.

The top view which concerns on 1st embodiment of this invention. Action | operation explanatory drawing which concerns on FIG. FIG. 2 is a schematic end view according to the embodiment. The end elevation corresponding to Drawing 3 concerning a second embodiment of the present invention. The figure which shows the Example of this invention as a table | surface.

<First embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 3, the bubble sheet 1 of the present embodiment is a hollow sheet having flexibility, and is made of a synthetic resin. Specifically, the bubble sheet 1 includes a cap film 11 having a large number of cap-shaped protrusions 13 and a back film 12 attached to the cap film 11 on the opening side of the protrusions 13. The bubble sheet 1 is the same as the conventional product in that it has a two-layer structure including a cap film 11 and a back film 12.

  Further, as shown in FIGS. 1 and 2, the bubble sheet according to the present embodiment has notches 17 at equal intervals by making the edge in the width direction perpendicular to the flow direction into a sawtooth edge 16 formed in a sawtooth shape. Is forming. Thereby, as shown in FIG. 2, when the air bubble sheet 1 is cut with fingers or the like in the width direction, it is cut so as to be preferentially torn from the position of the notch 17.

  As shown in FIGS. 1 to 3, 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 FIG. 1. As the material of the cap film 11, not only ordinary polyethylene but also polyolefin such as polypropylene, ethylene-vinyl acetate copolymer, nylon and many other types of plastics can be used. In this embodiment, the cap film 11 does not include a cyclic olefin copolymer described later.

  As shown in FIGS. 1 to 3, 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 FIG. 1, 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. 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.

  Thus, the bubble sheet 1 of the present embodiment has easy cutability in the width direction perpendicular to the flow direction by adding, for example, 10 to 50% of the cyclic olefin copolymer to the back film 12. Specifically, the back film 12 is blended with 10 to 50% of a cyclic olefin copolymer and 50 to 90% of low density polyethylene having an MFR value of 2 to 15.

  By applying the above composition, in this embodiment, the back film 12 has a structure in which cyclic olefin copolymers forming fine islands are randomly scattered between low density polyethylene. With such a configuration, the strength of the cyclic olefin copolymer is lower than that of the low density polyethylene having an MFR value of 2 to 15, so that the island-shaped cyclic olefin copolymer is preferentially broken when torn in the width direction. Then, the breaking force is broken while propagating one after another to similar island-shaped cyclic olefin copolymers adjacent in the width direction. As a result, the air bubble sheet 1 according to the present embodiment has obtained excellent straight cut performance that does not deviate from the tearing direction, in other words, the width direction that is the load direction.

  As described above, the bubble sheet 1 according to the present embodiment constitutes a perforation to reduce the buffering capacity, or coats a special layer to reduce transparency or complicate the structure. While avoiding defects, it has effectively acquired the straight-cut property in the width direction, that is, ease of hand cutting for the user. That is, the air bubble sheet 1 according to the present embodiment achieves high easy-to-cut characteristics in the width direction without impairing the buffer performance and transparency.

  In the present embodiment, the cyclic olefin copolymer is included only in the back film 12 which is a layer other than the cap film 11 having the thinnest portion of the film in the normal bubble sheet 1. In other words, the back film 12 is blended with 50 to 90% of low density polyethylene having a cyclic olefin copolymer of 10 to 50% and an MFR (melt flow rate) value of 2 to 15, so that it can be easily cut in the width direction. It guarantees the characteristics that can be cut.

  And in this embodiment, the bubble 14 is made hard to be destroyed by applying the aspect in which the said cyclic olefin copolymer is not contained in the said cap film 11, and the buffering performance is maintained effectively.

  In particular, by applying an aspect in which the cyclic olefin copolymer is not included in the cap film 11 of this embodiment, the straight cut performance is further improved. More specifically, when the cap film 11 is vacuum-formed to form the protrusions 13, the resin is radially oriented from the center of the circular protrusion 13 in plan view as in this embodiment. Here, when the cyclic polyolefin copolymer is blended with the cap film 11, the direction of easy cutting is also arranged radially from the center of the protrusion 13 toward all directions. Therefore, when the direction of the tear load disappears in parallel from the width direction, the tear load is torn along the load direction. Here, in this embodiment, the protrusions 13 forming the bubbles 14 are staggered in the flow direction as described above, and all the protrusions 13 are vacuum-formed. Therefore, when the protrusion 13 is torn in the oblique direction along the direction in which the resin is oriented, the tear load is propagated from the protrusion 13 to the protrusion 13 positioned in the oblique direction, and the direction of the tear load is from the width direction. It is because it will shift further. In general, the film used for the cap film 11 is generally set to have the largest thickness dimension in comparison with the back film 12 and the liner film (not shown) applied in the case of a film having a three-layer structure. Is done. Therefore, the cap film 11 is most likely to affect the cutting direction of the bubble sheet 1. Therefore, when the cyclic olefin copolymer is blended with the cap film 11, the above-described problem of the shift in the tearing direction is easily caused.

  Moreover, in order to avoid the stringing at the time of tearing becoming large because MFR of the low density polyethylene of MFR2-15 mix | blends 50 to 90% as mentioned above, and MFR of the raw material which comprises the bubble sheet 1 is low. It is. This also effectively reduces the feeling of resistance due to elongation during tearing and curls due to the elongation of the end face after tearing.

  In this embodiment, the serrated edge 16 is formed so as to form the notches 17 at both edges in the width direction in order to further improve the rectilinear cutting property in the width direction. Thereby, the tear load at the time of tearing to the width direction will act on the notch 16 preferentially, and the user can cut the bubble sheet 1 with small force.

  As mentioned above, although 1st embodiment of this invention was described, the bubble sheet of this invention is not restricted to the thing of 2 layer structure, As 2nd embodiment described below, the bubble sheet of this invention is equipped with a liner film. Alternatively, a three-layer structure may be used.

<Second embodiment>
Hereinafter, the bubble sheet 10 according to the second embodiment of the present invention will be described. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Therefore, in this embodiment, description of the cap film 11 and the back film 12 is abbreviate | omitted.

  The liner film 15 is thinner than 200 μm, and in this embodiment, the thickness dimension of the liner film 15 is set to about 7 μm, for example. In addition, as for the thickness dimension of the liner film 15, 7 micrometers-25 micrometers are preferable. The liner film 15 is flat and has no irregularities, and is attached to the tip end side of the protrusion 13 of the cap film 11.

  Thus, the air bubble sheet 10 of the present embodiment is easily cuttable in the width direction perpendicular to the flow direction by adding, for example, 10 to 50% of the cyclic olefin copolymer in the liner film 15 as well as the back film 12. It is supposed to have. Specifically, the back film 12 is blended with 10 to 50% of a cyclic olefin copolymer and 50 to 90% of low density polyethylene having an MFR value of 2 to 15.

  Of course, even the air bubble sheet 10 having such a three-layer structure includes a cyclic olefin copolymer other than the cap film 11, that is, the back film 12 and the liner film 15. Easy cutability in the direction can be effectively secured.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, only the main aspect of the bubble sheet has been disclosed. Of course, the bubble sheet has any additive, such as a colorant, a filler, an antioxidant, an antistatic agent, and an antibacterial agent. A combustion aid or the like may be added. The shape of the bubbles (projections, cavities) is not limited to a cylindrical shape, and can be variously changed. Further, the arrangement of the bubbles (projections, cavities) is not limited to the staggered arrangement, and can be variously changed.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Examples of the present invention will be described below, but the present invention is not limited to the examples.

<Elmendorf tear test>
An Elmendorf tear test was conducted using an example in which a cyclic olefin copolymer was blended with a back film and a liner film, and the magnitude of the tear load in the width direction was compared with that of the comparative example.

<1. Test Material>
As an example, 20% cyclic olefin copolymer (trade name TOPAS 9605F-500) and 80% low density polyethylene (trade name Sumikasen G701) having an MFR value of 7 are blended in the back film and liner film. A bubble sheet having a three-layer structure to which a material not containing a cyclic olefin copolymer was applied was applied to the film.

Comparative Example A normal bubble sheet having the same weight as the above example was applied. That is, a bubble sheet having a three-layer structure and containing no cyclic olefin copolymer in any of the back film, cap film and liner film was applied.

<2. Test method>
In accordance with JIS K 7128, an Elmendorf tear test in which a tear load of up to 32 N was applied was performed in both the examples and comparative examples. Originally, in JIS K 7128, the test was performed with an incision made in Examples and Comparative Examples, but in this test, the test was performed without making an incision.

  For the examples and comparative examples, the tear strength in the flow direction and the width direction was measured 5 times in total. The average value of these five tests and the tear strength value (%) in the width direction / flow direction were determined, and the ease of cutting in the width direction of the bubble sheet, that is, easy cutability was investigated.

<3. Test results>
The test results are shown as a table in FIG. As shown in the figure, the value of the first and second width direction tear loads in the example was larger than the second width direction tear load in the comparative example, but the average value of the five times Compared to the comparative example 19.17N, the example obtained a clearly lower value of 12.09N. The tear strength value (%) in the width direction / flow direction was clearly lower than the value of 236.54% in the comparative example, 185.1%, which is 200% or less in the example. Thereby, it became clear that the bubble sheet which concerns on an Example is excellent in the easy cut property of the width direction compared with the comparative example.

  The present invention can be used as a bubble sheet used for cushioning materials and the like.

DESCRIPTION OF SYMBOLS 1,10 ... Bubble sheet 11 ... Cap film 12 ... Back film 15 ... Liner film 17 ... Notch

Claims (4)

A bubble sheet comprising a cap film having a cap-shaped protrusion and a back film attached to the open side of the protrusion, and formed into a long sheet shape,
A bubble sheet characterized by having an easy-cut property in the width direction perpendicular to the flow direction when 10 to 50% of a cyclic olefin copolymer is added to at least one of the layers. It has a two-layer structure provided with the cap film and the back film,
The back film contains 10 to 50% of a cyclic olefin copolymer and 50 to 90% of low density polyethylene having an MFR value of 2 to 15, and the cap film does not contain the cyclic olefin copolymer. Item 1. A bubble sheet according to Item 1. It has a three-layer structure including the cap film, the back film and the liner film,
One or both of the back film and the liner film is blended with 10 to 50% of the cyclic olefin copolymer and 50 to 90% of low density polyethylene having an MFR value of 2 to 15, and the cap film. The bubble sheet according to claim 1, wherein the cyclic olefin copolymer is not contained.   The bubble sheet according to claim 1, 2 or 3, wherein a notch is formed at an edge in the width direction.

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