Packaging material

Abstract

To suppress breakage of a corrugated cardboard by a resin band, and to suppress deflection of the resin band, even when the corrugated cardboard expands / contracts according to an environmental change.SOLUTION: A packaging material includes: a pedestal for mounting a large-type machine; a side surface cover made of a corrugated cardboard for surrounding a side surface of the large-type machine; a top cap made of a corrugated cardboard for covering an upper part of the large-type machine; and a resin band wound around the pedestal, the side surface cover and the top cap in a vertical direction. The top cap includes: a horizontal part coming into contact with an upper surface of the large-type machine; a vertical part coming into contact with an inner surface of the side surface cover; and a corner cut as an inclined surface for connecting the horizontal part and the vertical part. A clearance x0 as a distance from an upper end of the side surface cover to an upper surface of the top cap under a low humidity environment that become a reference is set by the following formula: x0>A+B in which A is a value obtained by multiplying the total height of the side surface cover by an expansion rate of the corrugated cardboard under a high humidity environment, and B is a height of the corner cut of the top cap.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a packaging material for packaging large machines such as a hot water storage unit for a water heater. [Background technology]

[0002] Conventionally, when packaging large machinery such as the hot water storage unit of a water heater, it has been common to combine a cardboard packaging material that forms the outer shell with a foamed plastic packaging material such as EPS (Expanded Poly-Styrene) that acts as a protective material for the large machinery inside the shell.

[0003] However, since it is more difficult to recycle or dispose of foamed plastic packaging materials than cardboard packaging materials, foamed plastic protective materials have been gradually replaced by cardboard protective materials in recent years in order to reduce the environmental impact.

[0004] As a prior art related to cardboard protective materials, the cardboard product protective material of Patent Document 1 is known. For example, the abstract of the document states that "the objective of the present invention is to provide a cardboard product protective material that is a plate-shaped protective material or a modified protective material similar thereto that is arranged on the top, bottom or sides of products such as fruit that are mainly stored in packaging boxes such as cardboard boxes, is suitable for protecting products that are easily damaged, is inexpensive, recyclable, and contributes to reducing waste," and states that the solution is "a five-layer structure consisting of a back liner 6 and a core 5 that constitute an A-type single-faced cardboard component, and a core 4, a core 3, and a front liner 2 that constitute a B-type double-faced cardboard component, and at least the back liner 6 and the core 5 of the A-type component are made of kraft paper or thin paper other than cardboard base paper." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-211666 A Summary of the Invention [Problem to be solved by the invention]

[0006] Packing boxes for large machines can be stored or transported in various environments. Since cardboard expands and contracts depending on humidity, cardboard packaging materials expand when stored in a high humidity environment and shrink when stored in a low humidity environment.

[0007] Here, in order to maintain the integrity and strength of the packaging box and to improve the convenience during transportation, a resin band made of polypropylene or the like is often wrapped around the outer periphery of the packaging box. Since this resin band does not expand or contract depending on humidity, if only the cardboard packaging material expands in a high humidity environment, the tension of the resin band wrapped around the cardboard increases, and the cardboard may be damaged at the contact point with the resin band. In addition, if the cardboard packaging material shrinks in a low humidity environment after the cardboard is damaged in a high humidity environment, the tension of the resin band wrapped around the shape of the packaging box before the damage may decrease, causing the resin band to bend, i.e., the integrity and strength of the packaging box may deteriorate.

[0008] Therefore, an object of the present invention is to provide a cardboard packaging material that can prevent damage to the cardboard caused by resin bands and can prevent the resin bands from bending even if the cardboard packaging material expands and contracts in response to environmental changes. [Means for solving the problem]

[0009] In order to solve the above problems, the packaging material of the present invention is a packaging material for packaging large machines, comprising a base on which the large machine is placed, a cardboard side cover surrounding the side of the large machine, a cardboard top cap covering the upper part of the large machine, and a resin band wrapped vertically around the base, the side cover, and the top cap, the top cap having a horizontal part that contacts the upper surface of the large machine, a vertical part that contacts the inner surface of the side cover, and a corner cut that is a slope connecting the horizontal part and the vertical part, and the packaging material has a clearance x0, which is the distance from the upper end of the side cover to the upper surface of the top cap in a reference low-humidity environment, set by the following formula: x0 > A+B, where A is the total height of the side cover multiplied by the elongation rate of the cardboard in a high-humidity environment, and B is the height of the corner cut of the top cap. Effect of the Invention

[0010] According to the packaging material of the present invention, even if the cardboard expands and contracts in response to environmental changes, damage to the cardboard caused by the resin bands can be suppressed, and deflection of the resin bands can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is an external view of a large machine in a packaged state, the large machine being packaged using the packaging material of the first embodiment. [Diagram 2] FIG. 3 is a cross-sectional view of the upper part of the packaging box of the first embodiment. [Diagram 3] 4A and 4B are cross-sectional views of top caps of a comparative example and Example 1. [Figure 4] FIG. 11 is a diagram showing an example of a storage state of the packing box of the second embodiment in a warehouse. [Diagram 5] 1 is a graph showing an example of actual measured values ​​of change in cardboard thickness over time when a load is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the packaging material of the present invention will be described with reference to the drawings. EXAMPLES

[0013] First, a packaging material 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0014] 1 is an external view of a large machine 2 (hereinafter referred to as a "packaging box 3") in a packaged state, which has been packaged using packaging material 1 according to this embodiment. In the following, the top, bottom, front, back, left and right directions are defined as shown in the figure.

[0015] In Figure 1, a large machine 2, such as a hot water storage unit for a water heater, is placed on a wooden base 11, the four sides of the large machine 2 are surrounded by side covers 12, which are a first corrugated board packaging material, and the top of the large machine 2 is covered by a top cap 13, which is a second corrugated board packaging material.After that, two plastic bands 14 are wrapped vertically along the four sides of the front, top, back and bottom of the packaging box 3, thereby forming a packaging box 3 in which the base 11, side covers 12 and top cap 13 are integrated.

[0016] Fig. 2 is a cross-sectional view of the upper part of the packaging box 3 under a certain environment. Note that Fig. 2 is a conceptual diagram mainly for explaining the distance from the upper end of the side cover 12 to the upper surface of the top cap 13 (hereinafter referred to as "clearance x"), and therefore the dimensional ratios of each part in the figure do not match the actual dimensional ratios.

[0017] As shown in Fig. 2, the top cap 13 has a horizontal portion 13a and a vertical portion 13b. The horizontal portion 13a is also a protective material that protects the upper portion of the large machine 2, and is therefore made of thick cardboard with a two-layer structure to enhance cushioning. A recess that fits the upper portion of the large machine 2 is provided in advance in the center of the lower surface of the horizontal portion 13a, thereby suppressing horizontal sliding of the top cap 13. On the other hand, the vertical portion 13b, which is not expected to come into contact with the large machine 2, is made of thin cardboard with a single layer structure and is arranged to come into contact with the inner surface of the side cover 12.

[0018] In a standard environment of normal temperature and low humidity (for example, an environment of a temperature of 27°C and a humidity of 30%), the cardboard does not expand, and the distance from the upper end of the side cover 12 to the upper surface of the cap 13 is approximately equal to the clearance x0 planned at the time of designing the packaging box 3. However, since the clearance x increases and decreases depending on the humidity, if the clearance x0 at the time of design is inappropriate, the cardboard may be damaged at the contact portion with the resin band 14 when the cardboard expands in a high humidity environment, or the resin band 14 may bend when the cardboard shrinks in a low humidity environment after the cardboard is damaged. Therefore, in this embodiment, the clearance x0 is set in consideration of the following circumstances.

[0019] <Effects of expansion of cardboard> As described above, cardboard has the property of expanding when it absorbs moisture. Therefore, cardboard expands in a high humidity environment and shrinks in a low humidity environment. This property becomes more pronounced as the dimensions of the cardboard become larger. For example, if the side cover 12 has a total height H of 2100 mm under the standard environment, a large expansion of more than 20 mm will occur when the cardboard expansion rate under a high humidity environment is 1%.

[0020] 2, if the upper end of side cover 12 extends above the upper surface of top cap 13 (if clearance x<0), the contact state between the upper edge of resin band 14 and the cardboard will change from line contact with the upper surface of top cap 13 to point contact with the upper end of side cover 12. In that case, the upper edge of resin band 14 will push down the upper end of side cover 12 in reaction to the force of the upper end of side cover 12 pushing up the upper edge of resin band 14, and so there is a possibility that the cardboard will be damaged at the upper end of side cover 12, which is weaker than resin band 14.

[0021] Therefore, in order to avoid damage to the upper end of the side cover 12 in a high humidity environment, it is necessary to set the clearance x0 in the reference environment taking into account the maximum extension amount of the overall height H of the side cover 12.

[0022] <Effect of corner cutting> FIG. 3 is a cross-sectional view of a top cap 13' of a comparative example and the top cap 13 of this embodiment, showing the difference in shape of the front and rear corners of the top caps.

[0023] In the comparative example of top cap 13' shown in Fig. 3(a), the vertical front surface is directly connected to the horizontal top surface, and the horizontal top surface is also directly connected to the vertical rear surface. If this configuration is adopted, when plastic band 14 is tightened as shown in Fig. 1, stress from plastic band 14 is concentrated on the front and rear corners of top cap 13', and the front and rear corners may be crushed.

[0024] Therefore, in the top cap 13 of this embodiment shown in Fig. 3(b), slopes (hereinafter referred to as "corner cuts") are provided at the front and rear corners to prevent crushing at the front and rear corners by dispersing the stress generated at the front and rear corners of the top cap 13 when the resin band 14 is fastened. Note that Fig. 3(b) illustrates an example of a configuration in which corner cuts are provided at the front and rear corners of the top cap 13, but instead of the corner cuts, curved surfaces with a predetermined curvature may be arranged.

[0025] 3(b), the position of the upper end of the side of top cap 13 will move downward by the illustrated distance L compared to the position of the upper end of the side of top cap 13' in the comparative example. When the position of the upper end of the side of top cap 13 is lowered in this way, the distance between the upper end of side cover 12 and the upper end of the side of top cap 13 will be shortened, so that the upper end of side cover 12 that extends upward in a high humidity environment will easily exceed the upper end of the side of top cap 13, and for the same reason as above, there is a possibility that resin band 14 will damage the cardboard at the upper end of side cover 12.

[0026] Therefore, in order to avoid damage to the upper end of side cover 12, it is necessary to set clearance x0 under the reference environment, taking into account the height (distance L) of the corner cut of top cap 13.

[0027] <How to determine clearance x0 under standard environment> As described above, the reason why the cardboard at the upper end of side cover 12 is damaged by the resin band is thought to be that the upper end of side cover 12 extends upward in a high humidity environment, causing the upper end of side cover 12 to exceed the upper end of the side surface of top cap 13, and that the corner cut in top cap 13 causes the upper end of side cover 12 to exceed the upper end of the side surface of top cap 13.

[0028] Therefore, in this embodiment, the size of the clearance x0 under the standard environment is set to satisfy the following formula 1 so that the upper end of the side cover 12 does not exceed the upper end of the side of the top cap 13 even if both occur simultaneously.

[0029] x0 > A + B (Eq. 1) In addition, element A is the total height H of the side cover 12 multiplied by the elongation rate of the cardboard in a high humidity environment, and element B is the height of the corner cut of the top cap 13 (corresponding to the distance L in Figure 3 (b)).

[0030] For example, if the total height H of side cover 12 is 2100 mm, the elongation rate of the cardboard when moved from a standard environment to a high-humidity environment is 1%, and the height (distance L) of the corner cut of top cap 13 is 10 mm, then by setting clearance x0 to greater than 31 mm, even in a high-humidity environment, the upper end of side cover 12 will not exceed the upper end of the side of top cap 13, thereby avoiding a situation in which resin band 14 damages the cardboard at the upper end of side cover 12 or a situation in which resin band 14 bends after the cardboard is damaged. EXAMPLES

[0031] Next, a packaging material 1 according to a second embodiment of the present invention will be described with reference to Figures 4 and 5. Note that a duplicated description of the points common to the first embodiment will be omitted.

[0032] FIG. 4 is a diagram showing an example of the storage state of packing boxes 3 in a warehouse. In this example, in order to increase the storage efficiency of the warehouse, the packing boxes 3 are stacked up to three levels using a forklift 4 or the like. When the packing boxes 3 are stacked three levels, the weight of the packing boxes 3 of the upper two levels (approximately 200 kg if the large machine 2 is a hot water storage unit of a water heater) is placed on the top surface (horizontal portion 13a of the top cap 13) of the bottommost packing box 3. Here, cardboard has the characteristic that if it continues to receive a load of more than a certain level, the core placed between the liners gradually collapses and the thickness gradually decreases.

[0033] Figure 5 shows the load applied to a two-ply corrugated board with a thickness of 8 mm under no load and a rated load of 625 kg / m 2 1 is a graph showing an example of actual measured values ​​of change in cardboard thickness over time when a load (corresponding to the maximum load applied to the top cap 13 of the bottommost packing box 3 in FIG. 4) is continuously applied. Note that the dashed-dotted line in the figure shows an approximation graph of change in cardboard thickness over time in a first low-humidity environment (temperature 55°C, humidity 30%), and the dashed-two-dotted line shows an approximation graph of change in cardboard thickness over time in a second high-humidity environment (temperature 20°C, humidity 90%).

[0034] Since the expansion of the cardboard is small in the first environment with low humidity and large in the second environment with high humidity, the initial value of the thickness of the top caps 13 is larger in the second environment than in the first environment, as shown in the figure. However, after a sufficient number of days (e.g., 37 days) have passed under load, the top cap thickness converges to approximately the same in both environments. In other words, as long as the rated number of layers of the packaging box 3 is observed, there is an upper limit to the reduction in thickness of the top caps 13.

[0035] Therefore, in this embodiment in which the packing boxes 3 are to be stacked, the clearance x0 under the reference environment is set in consideration of the limit of thinning of the top cap 13. Specifically, the clearance x0 is set by the formula 2, which takes into consideration the elements A and B given in the formula 1, as well as the element C of the maximum value of the top cap thickness reduction when the rated load is applied to the top cap 13.

[0036] x0 > A+B+C (Eq. 2) For example, if the total height H of side cover 12 is 2100 mm, the elongation rate of the cardboard when moved from a standard environment to a high-humidity environment is 1%, the height of the corner cut of top cap 13 is 10 mm, and the maximum design thickness reduction of top cap 13 is 4 mm, then by setting clearance x0 to greater than 35 mm, even in a high-humidity environment and a stacked packaging box environment, the upper end of side cover 12 will not exceed the upper end of the side of top cap 13, thereby avoiding a situation in which resin band 14 damages the cardboard at the upper end of side cover 12 or a situation in which resin band 14 bends after the cardboard is damaged. EXAMPLES

[0037] Next, a packaging material 1 according to a third embodiment of the present invention will be described. Note that a duplicated description of the points common to the second embodiment will be omitted.

[0038] A certain degree of manufacturing error is allowed for the total height H of the cardboard side cover 12. For example, if the allowable error for the total height H is ±10 mm, the position of the top end of the side cover 12 may move up to 10 mm from the design value, and the top end of the side cover 12 and the top surface of the top cap 13 may be closer than the design value (see FIG. 2).

[0039] Therefore, in this embodiment, which allows for manufacturing errors in the packaging box 3, the clearance x0 is set using equation 3, which takes into account not only elements A, B, and C listed in equation 2 of embodiment 2, but also element D of the allowable error of the overall height H of the side cover 12.

[0040] x0 > A+B+C+D (Eq. 3) For example, if the total height H of side cover 12 is 2100 mm, the elongation rate of the cardboard when moved from a standard environment to a high-humidity environment is 1%, the height of the corner cut of top cap 13 is 10 mm, the maximum design thickness reduction of top cap 13 is 4 mm, and the allowable error of the total height H of side cover 12 is ±10 mm, then by setting clearance x0 to greater than 45 mm, even under conditions of a high-humidity environment, a stacked environment of packaging boxes, and the error in total height H is the maximum value within the allowable range, the upper end of side cover 12 will not exceed the upper end of the side of top cap 13, thereby avoiding a situation in which resin band 14 damages the cardboard at the upper end of side cover 12 or a situation in which resin band 14 bends after the cardboard is damaged. [Explanation of symbols]

[0041] 1 Packaging materials 11 Pedestal 12 Side cover 13 Top Cap 14 Resin Band 2 Large machines 3 Packing box 4. Forklift

Claims

1. A packaging material for packaging large machinery, A base on which the large machine is placed; A side cover made of cardboard that surrounds the side of the large machine; A cardboard top cap that covers the top of the large machine; a resin band that is wound around the base, the side cover, and the top cap in a vertical direction; Equipped with the top cap has a horizontal portion that contacts the top surface of the large machine, a vertical portion that contacts the inner surface of the side cover, and a corner cut that is a slope connecting the horizontal portion and the vertical portion, A packaging material characterized in that a clearance x0, which is the distance from the upper end of the side cover to the upper surface of the top cap in a reference low humidity environment, is set according to the following formula. x0 > A+B... (Formula 1) A is the total height of the side cover multiplied by the elongation rate of the cardboard in a high humidity environment, B is the height of the corner cut of the top cap.

2. The packaging material according to claim 1, A packaging material characterized in that the clearance x0 is set according to the following formula. x0 > A+B+C... (Formula 2) C is the maximum value of the top cap thickness reduction when the rated load is applied.

3. The packaging material according to claim 2, A packaging material characterized in that the clearance x0 is set according to the following formula. x0 > A+B+C+D... (Formula 3) D is the maximum allowable error in the overall height of the side cover.

4. The packaging material according to any one of claims 1 to 3, A packaging material characterized in that the bottom surface of the top cap is provided with a recess that fits into the top surface of the large machine.

5. The packaging material according to any one of claims 1 to 3, The packaging material is characterized in that the low humidity environment is an environment with a humidity of 30%, and the high humidity environment is an environment with a humidity of 90%.

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