JP5312915B2 - Air bubble sheet for corrugated cardboard - Google Patents

Description

  The present invention relates to an air bubble sheet for corrugated cardboard that is preferably used for packaging and the like.

  The present applicant has already proposed a bubble sheet that can be used as a substitute for cardboard (see, for example, Patent Document 1).

  At this time, the present inventors have presented a sheet-like material that is softer than what has been conventionally called plastic corrugated cardboard. However, if the properties of such a sheet-like material are set too soft, it becomes difficult to handle in the same way as so-called corrugated cardboard. However, there was a case that could not be sealed well because it was not enough.

  On the other hand, what is conventionally called a plastic corrugated cardboard is not only hard but also has a large repulsive force and cannot be used in an automatic sealing machine for A-type cardboard boxes. These machines are usually designed to bend a sheet through a guide roll or an arm, put a crease and then apply a tape or a hot melt. However, if the hardness or repulsive force is too large, there are problems that the tape is peeled off by that force, and the bonded surface is peeled off before the hot melt is cooled and solidified.

  The inventors of the present invention have a bending strength measured by the method specified in JIS K 7203 of 0.001 MPa or more and 10 MPa or less, and measured the bending stiffness twice in succession by the method specified in JIS K 7106 for the same specimen. If the air bubble sheet is set so that the second numerical value is 50% or more, more preferably 65% or more of the first numerical value, the hardness of the flap portion is within the range where the above-mentioned peeling problem does not occur. It was found that the repulsive force was sufficient and it was possible to apply the above-mentioned automatic sealing machine.

  However, in order to satisfy the above conditions with a conventional two-layer or three-layer bubble sheet and to have a certain level of independence when a box is made, the weight per unit area must be considerably large. Did not get.

  The increase in weight is not preferable from the increase in the estimated amount of carbon dioxide generated due to the recently implemented Containers and Packaging Recycling Law and the increase in raw materials used.

  Accordingly, the present inventors have further pursued a search to produce a bubble sheet that is as light as possible and has a low environmental load while satisfying the above conditions.

  Therefore, first, the present inventors paid attention to the balance of the thicknesses of the cap film, the back film, and the liner film in order to reduce the weight without unduly reducing the strength (strength) of the bubble sheet. As an extension, the inventors have taken into consideration the particle arrangement of the bubbles and obtained knowledge that is the basis of the present invention.

Incidentally, a product such as a bubble sheet was originally a two-layer product of a cap film and a back film in view of its formation. However, when such a bubble sheet is used to make a bag with the cap film on the inside, the grains in the bag interfere with each other, making it difficult to put the contents. In order to improve this, a thin film was stuck on the top of the cap film at the beginning of the three-layer bubble sheet. Thus, the thickness of the liner film in the conventional three-layer bubble sheet is at most 10 to 15% of the total sheet thickness of all the layers, and its existence significance and configuration are completely different from those of the present invention.
Japanese Patent Application No. 2004-34594

  The present invention has been made on the basis of the above circumstances and knowledge, and it is difficult to apply to a widely used automatic sealing machine for A-type corrugated cardboard, and it is mainly applied to the automatic sealing machine. In addition, it is intended to solve the problem that the weight per unit area tends to increase if it is developed, and it can be appropriately packed using the automatic sealing machine as an alternative to corrugated cardboard. The purpose of the present invention is to provide an air bubble sheet that is suitable for corrugated cardboard and has a low level of environmental impact.

In order to achieve this object, the present invention employs the following configuration. That is, the air bubble sheet for corrugated cardboard according to the present invention comprises a two-layer air bubble sheet portion that has a cap film and a back film, and is laminated with the caps facing each other, and the following (a) to ( An air bubble sheet instead of corrugated cardboard, characterized by satisfying all the conditions of d).
(A) Each bubble particle of one bubble sheet portion, that is, a cap formed on the cap sheet, overlaps in plan view with a plurality of particles of each bubble of the other bubble sheet, that is, a plurality of caps formed on the cap sheet. (FIG. 3).
(B) The bending strength measured by the method defined in JIS K 7203 is 0.001 MPa or more and 10 MPa or less.
(C) When bending stiffness is measured twice by the method defined in JIS K 7106, the second numerical value is 50% or more of the first numerical value.
(D) As shown in FIG. 1, when the bubble particle arrangement is D, the bubble arrangement pitch is P, the bubble arrangement pitch between adjacent rows is θ, and P = 1. 05D to 1.3D, θ = 50 ° to 65 °.

  Here, the description about the bending strength of (b) and the description of the bending stiffness of (c) are the conditions for causing the bubble sheet to exhibit strength characteristics equivalent to that of cardboard, in other words, an automatic sealing machine for cardboard. However, it is based on the knowledge obtained after many trials and errors as described above.

  That is, if the bending strength shown in (b) exceeds 10 MPa, the hardness and repulsive force of the bubble sheet are excessively increased and the surface once bonded by the automatic sealing machine is liable to be peeled off. On the other hand, when the pressure is less than 0.001 MPa, the waist becomes extremely weak, so that the measurement defined in JIS K 7203 is practically impossible. It can cause a situation where the flap cannot be closed and the tape cannot be fixed properly. Further, when the characteristic value related to the bending stiffness shown in (b) is less than 50%, it becomes easy to fold, and automatic sealing is impossible practically due to the fall of the flap. The larger the characteristic value regarding bending stiffness, the better. However, no matter what film material is used, there is an upper limit due to the nature of the substance, and there is virtually no 100%.

On the other hand, the description relating to the arrangement of the grain arrangement (a) (FIG. 3 ) and the description relating to the grain arrangement (d) were found in the process of searching for an optimum balance of thickness and grain arrangement from the viewpoint of resource saving. The disclosed conditions are disclosed.

The particles formed in each bubble sheet portion, that is, the bubbles formed in one bubble sheet portion, that is, the cap formed on the cap sheet, are converted into the plurality of particles formed in each bubble in the other bubble sheet, that is, the plurality of caps formed on the cap sheet. On the other hand, if it deviates from the configuration in which it is arranged so as to overlap in plan view (FIG. 3) , the structural balance in terms of strength is totally or partially broken, and the strength of the waist is unduly reduced. It becomes difficult to reduce the weight. Further, if the bending strength is improved, the interval between the bubbles should be narrow, but a wider one is advantageous for increasing the sealing property of the bubbles since a sufficient fusion allowance can be obtained. According to the study of the present inventor, the condition range of (d) described above has the best balance in practical use, and both waist strength and weight reduction can be achieved.

  With the air bubble sheet having such a configuration, there is an effect that a sealing work having no practical problem can be performed on the corrugated cardboard automatic sealing machine by satisfying the conditions (b) and (c). In addition to the above, the conditions (a) and (d) are satisfied, so that the structural strength balance is good, and a moderate amount of independence when a box is made is realized using less material. It becomes possible to do.

Incidentally, the one film may be interposed between the layers of bubble wrap portion of said second layer. As a preferable aspect in that case, what made the side which touches a cap film a sealant layer can be mentioned. That is, it may be formed by sticking to both cap films via a sealant layer.

  Moreover, if it further has a sealing part which fixes by sealing the outer periphery of the said 2 layer bubble sheet part, it will become possible to laminate | stack a 2 layer bubble sheet part more reliably.

  Since the present invention is configured as described above, it can be applied to a corrugated cardboard automatic sealing machine, and is excellent in structural balance for securing the strength of the waist. It is possible to provide an air bubble sheet that can be used instead of corrugated cardboard and has a low environmental load.

  As shown in FIG. 4, a corrugated cardboard bubble sheet (hereinafter referred to as a bubble sheet) A according to the present embodiment forms a box B that can be suitably applied to packing and transporting packages. The box B is formed in the same manner as a normal cardboard box by an automatic sealing machine for A-type cardboard, which is widely used for manufacturing a general cardboard box B, for example.

  Here, as shown in FIGS. 1, 2, 3 and 5, the air bubble sheet A according to the present embodiment has a cap film 1 and a back film 2 and is laminated with the caps facing each other. It has two layers of air bubble sheet portions A11 and A12, and satisfies all the following conditions (a) to (d). (A) The direction in which the particles are arranged in each of the bubble sheet portions A11 and A12 is varied by 30 ° to 60 ° (FIG. 2). (B) The bending strength measured by the method defined in JIS K 7203 is 0.001 MPa or more and 10 MPa or less. (C) When bending stiffness is measured twice by the method defined in JIS K 7106, the second numerical value is 50% or more of the first numerical value. (D) When the particle arrangement of the bubbles b is D, the diameter of the bubbles b is P, the arrangement pitch of the bubbles b in the same row is P, and the deviation angle of the bubbles b between adjacent rows is θ, P = 1.05 D-1 .3D, θ = 50 ° to 65 ° (FIG. 1).

  In addition, although the bubble sheet A is typically shown in FIG. 3, the bubble sheet produced by the normal manufacturing method is actually used. That is, it should be noted in the bubble sheet manufacturing technique that the shape of the molded cap does not match the vacuum-molded mold shape. The cap film at the time of the production of the bubble sheet has just been molded from the molten state by the mold and is still at a high temperature, and the back film stuck to this is in contact in the molten state. It is at a high temperature. As a result of the air sealed in the space of a certain volume contracting due to a decrease in temperature, the shape of the bubble sheet contracts accordingly. That is why, as is well-known, none of the products are stretchy. To understand the outline, assuming that the air temperature at the time of bubble formation is 100 ° C. and the environmental temperature of the bubble sheet product is 20 ° C., the volume of the internal air is reduced to 78.5%. Should be. When actually measured, although it varies somewhat depending on the temperature conditions during production, the basis weight of the bubble sheet, the ratio of each film thickness, etc., it is generally in the range of 70 to 85%.

  Since bubble sheet products are always in this situation, they are used as a buffering agent, and when a load is applied in the surface direction, the air bubbles bulge out laterally by the air inside the bubble under pressure. , Calm down in a state where a "body blister" has occurred. In this way, the bubbles when functioning as a buffer are even lower than the height given by the mold cavity minus the amount of bubble volume reduction due to air cooling and shrinkage. In order to measure this state, for example, 10 sheets of air bubbles of length x 100 mm in width are stacked with 1 mm thick paper sandwiched between them, and a weight of 200 g is applied from the top. , And subtract the amount of cardboard to calculate the average bubble height.

  Hereinafter, the configuration of the bubble sheet A will be described.

  As shown in FIGS. 1, 2, 3, and 5, such a bubble sheet A has two bubble sheet portions A <b> 11 and A <b> 12 having the same arrangement of the caps 10 arranged in a direction in which the caps 10 face each other. Are stacked. And the said bubble sheet part A11, A12 has the cap film 1 and the back film 2, respectively.

  The cap film 1 can form the cap 10 in an arrangement as shown in FIG. 1. In this embodiment, for example, super random polypropylene having an ethylene content of 5 to 10% is used. The cap film 1 specifically has a cap 10 formed with a particle diameter D of 10 mm, a particle height of 4 mm, a distance between particles, that is, a pitch P of 11.5 mm, and bubbles b between adjacent rows, The displacement angle θ of the cap 10 is set to 60 ° (FIG. 1).

  The back film 2 can form air bubbles b together with the cap film 1, and in the present embodiment, super random polypropylene having an ethylene content of 5 to 10% is similarly used.

  Therefore, as shown in FIG. 2, the air bubble sheet according to the present embodiment differs in the direction in which the grains are arranged in the two air bubble sheet portions A11 and A12 by 30 ° to 60 °. By doing so, as shown in FIG. 3, the cap 10 that forms the particles of each bubble b of the one bubble sheet portion A <b> 11 has a plurality of bubbles b of the other bubble sheet A <b> 12. Are arranged so as to overlap in plan view. Therefore, as shown by an arrow in FIG. 5, for example, an impact applied to one of the bubbles b is dispersed in a plurality of the other bubble sheet portions A11 and A12, that is, three bubbles b in this embodiment. Since the area will diffuse more than three times, the air bubble sheet portions A11 and A12 are able to protect the contents, that is, the impact resistance can be remarkably improved in combination with the buffering force originally possessed. It has become.

  As described above, according to the bubble sheet A instead of corrugated cardboard according to the present embodiment, the above-described configuration allows the corrugated cardboard automatic sealing machine to meet the above conditions (b) and (c). Not only can the sealing work be carried out without any problem in practice, but the structural strength balance is improved by satisfying the conditions (a) and (d). It becomes possible to realize moderate self-supporting property when B is made using a small amount of material.

<Modification 1>
Hereinafter, although the modification of the said embodiment is demonstrated, while the same code | symbol is attached | subjected to the component corresponded to the said embodiment, the detailed description shall be abbreviate | omitted.

  That is, in the air bubble sheet A1 according to this modification, as shown in FIG. 6, a film for laminating a cap, for example, a film used as a sealant layer or a normal liner film is provided between the two air bubble sheet portions A11 and A12. 3 is assumed to be interposed.

  With such a configuration, the cap films 1 are bonded to each other via the film 3, and the particles of the air bubble sheet portions A <b> 11 and A <b> 12 are seen in a cross-section while reliably joining the cap films 1. It is the structure which mutually reinforces the film 3 which forms a flat line. Therefore, as shown by an arrow in FIG. 6, an impact applied to one bubble b of one of the bubble sheet portions A11 presses the film 3 to cause the other bubble sheet portion A12 to pass through the film 3. Since the pressure receiving area diffuses more than three times by being dispersed in a large number of at least three bubbles b, the contents are protected in combination with the cushioning force inherent to each of the bubble sheet portions A11 and A12. The possible force, that is, the impact resistance, can be further improved. That is, the air bubble sheet A1 according to the present modification is lightweight and further excellent in strength.

<Modification 2>
Also in Modification 2 described below, the same reference numerals are given to the components corresponding to the above-described embodiment, and the detailed description thereof is omitted as in the modification.

  That is, the air bubble sheet A2 according to the present modification example further includes a seal portion 4 that is fixed by sealing the outer periphery of the two layers of air bubble sheet portions A11 and A12, as shown in FIG.

  By adopting such a configuration, the two-layered bubble sheet portions A11 and A12 can be more reliably stacked.

  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-described embodiment, the configuration in which the back film is a single layer is disclosed. However, it is of course possible to have a configuration with two or more layers as long as the above conditions are satisfied.

  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 in detail below, but the present invention is not limited to these examples.

  In this example, using Example 1 corresponding to the bubble sheet of the above embodiment, and Comparative Example 1 and Comparative Example 2 as test materials, tests for bending strength and bending stiffness are performed as described below. We investigated the strength against impact.

<Test material>
As Example 1, a two-layer base sheet portion having a single-layer cap bonding sheet interposed therebetween was used. Specifically, the cap sheet and the back sheet are made of polyethylene as the material of the two-layer bubble sheet portion, and the thickness ratio of the cap sheet and the back sheet of the two-layer bubble sheet portion to the total thickness is 25% and 21 respectively. The cap laminated film for laminating the cap sheets of the two-layered bubble sheet portions was laminated at a thickness ratio of 7% with respect to the total thickness. These two-layer bubble sheet portions have a bubble particle size of 10 mm, a particle height of 4 mm, and a pitch between particles of 11.5 mm, and a bubble shift angle between adjacent rows of 60 °, Further, the gas bubbles were bonded to each other by changing the angle of the row of bubbles in the flow direction by 45 °. The weight of the bubble sheet was 140 g per square meter.
As Comparative Example 1, the cap sheet, the back sheet, and the liner sheet are made of polyethylene, and the thickness ratio of the cap sheet, the back sheet, and the liner sheet to the total thickness is 55%, 35%, and 10%, respectively. A bubble sheet having a diameter of 10 mm, a grain height of 4 mm, and a pitch between grains of 11.5 mm was used. The weight of the bubble sheet was 150 g per square meter.

<Test method>
The bending strength measured by the method defined in A-type JIS K 7203 and the bending stiffness measured by the method defined in JIS K 7106 were measured twice in succession.
And, it is a total of five times that a steel sheet with a diameter of 1/2 inch is placed on an iron table and dropped from a height of 40 cm to the above-described Example 1 and Comparative Example 1 placed thereon. An impact penetration test was performed. In the table, as the evaluation of the strength against impact, “◯” was entered when the carbon paper had no iron ball drop marks, and “X” was written when the drop marks were recognized.

<Test results>
The results of Example 1 and Comparative Example 1 in the test described above are shown in Table 1 below.

  As described above, Example 1 shows conditions that can be used as a corrugated cardboard substitute, excellent bending strength, and excellent characteristics that the second numerical value is 50% or more of the first numerical value in two tests. And it turned out that it is a corrugated-cardboard alternative bubble sheet which realized the further weight reduction with respect to the comparative example 1. FIG.

  Further, in Example 1, although the iron ball was dropped five times in the impact penetration test, no drop mark was observed in any of them. On the other hand, a drop mark having a diameter of 4.5 mm to 5 mm was observed in Comparative Example 1.

  That is, from the above results, although Example 1 is lighter, it has excellent bending strength, bending strength, and impact resistance, and has excellent performance as a bubble sheet instead of corrugated cardboard. It turns out to have. In other words, it has been clarified that the air bubble sheet as in Example 1 can be suitably applied to an A-type corrugated cardboard automatic sealing machine that is widely used in general.

Explanatory drawing which concerns on arrangement | positioning of the grain in the bubble sheet of this invention. Explanatory drawing which concerns on arrangement | positioning of the particle | grains of each bubble sheet part in the bubble sheet of this invention. Same as above. The external view of the box formed of the bubble sheet which concerns on one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view according to the embodiment. The typical sectional view concerning modification 1 of the embodiment. Structure explanatory drawing which concerns on the modification 2 of the embodiment.

Explanation of symbols

A, A1, A2 ... Corrugated cardboard bubble sheet (bubble sheet)
A11, A12 ... Bubble sheet part 1 ... Cap film 2 ... Back film 3 ... Film 4 ... Seal part b ... Bubble

Claims (3)

It has a cap film and a back film, and comprises two layers of air bubble sheet portions that are stacked in a direction facing each other, and satisfies all the following conditions (a) to (d): Air bubble sheet for corrugated cardboard.
(A) It arrange | positions so that the bubble particle | grains of one bubble sheet part may overlap with the several particle | grains of each bubble of the other bubble sheet part in planar view.
(B) The bending strength measured by the method defined in JIS K 7203 is 0.001 MPa or more and 10 MPa or less.
(C) When bending stiffness is measured twice by the method defined in JIS K 7106, the second numerical value is 50% or more of the first numerical value.
(D) When the bubble particle arrangement is D for bubble diameter, P for bubble arrangement pitch in the same row, and θ for the bubble shift angle between adjacent rows, P = 1.05D to 1.3D, θ = 50 ° to 65 °. The two-layer bubble wrap cardboard alternative of claim 1, wherein it is assumed that by interposing a sheet of film between the layer of the bubble wrap of the.   3. The corrugated cardboard substitute bubble sheet according to claim 1 or 2, further comprising a seal portion that is fixed by sealing an outer periphery of the two-layer bubble sheet portion.

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