Packing materials

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 of a water heater.

Background Art

[0002] Conventionally, when packaging large machines such as a hot water storage unit of a water heater, a cardboard packaging material constituting an outer shell and a foamed plastic packaging material such as EPS (Expanded Poly-Styrene) that functions as a protective material for the large machine inside the outer shell are often used in combination.

[0003] However, compared with the recycling and disposal of cardboard packaging materials, the recycling and disposal of foamed plastic packaging materials are difficult. Therefore, from the perspective of reducing environmental load, in recent years, foamed plastic protective materials are being replaced by cardboard protective materials.

[0004] As a conventional technology related to cardboard protective materials, the cardboard product protective material of Patent Document 1 is known. For example, in the abstract of the same document, the problem is described as "a plate-shaped or deformed protective material arranged on the upper and lower sides and side parts of products such as fruits stored mainly in packaging boxes such as cardboard boxes, suitable for protecting easily damaged products, and inexpensive and recyclable, contributing to the reduction of garbage. The problem is to provide a cardboard product protective material." The solution is described as "a five-layer structure of a back liner 6 and a core 5 constituting a single-sided cardboard component of type A, and a middle liner 4, a core 3, and a front liner 2 constituting a double-sided cardboard component of type B, characterized in that at least the back liner 6 and the core 5 of the type A component are thin papers other than kraft paper or cardboard base paper."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] Packaging boxes for large machinery can be stored or transported in a variety of environments. Cardboard expands and contracts depending on humidity, so when stored in a high-humidity environment, the cardboard packaging material will expand, and when stored in a low-humidity environment, the cardboard packaging material will contract.

[0007] In order to maintain the integrity and strength of the packaging box and to improve convenience during transportation, a resin band made of polypropylene or similar material is often wrapped around the outside of the packaging box. Since this resin band does not expand or contract in response to humidity, if only the cardboard packaging material expands in a high-humidity environment, the tension of the resin band wrapped around the cardboard will increase, and the cardboard may break at the point of contact with the resin band. Furthermore, if the cardboard packaging material shrinks in a low-humidity environment after being damaged in a high-humidity environment, the tension of the resin band, which was wrapped to match the shape of the packaging box before the damage, will decrease, and the resin band may sag, meaning that the integrity and strength of the packaging box may deteriorate.

[0008] Therefore, the present invention aims to provide a corrugated cardboard packaging material that can suppress damage to the corrugated cardboard caused by resin bands, and also suppress the bending of the resin bands, even when the corrugated cardboard packaging material expands and contracts in response to environmental changes. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides a packaging material for packaging large machinery, comprising: a base on which the large machinery is placed; corrugated cardboard side covers surrounding the sides of the large machinery; a corrugated cardboard top cap covering the top of the large machinery; and a resin band that is wrapped vertically around the base, the side covers, and the top cap. The top cap has a horizontal portion that contacts the top surface of the large machinery, a vertical portion that contacts the inner surface of the side covers, and a corner cut which is a slope connecting the horizontal portion and the vertical portion. The clearance x0, which is the distance from the top end of the side covers to the top surface of the top cap under a standard low-humidity environment, is set by the following formula: x0 > A + B, where A is the total height of the side covers multiplied by the elongation rate of the corrugated cardboard under a high-humidity environment, and B is the height of the corner cut of the top cap. [Effects of the Invention]

[0010] According to the packaging material of the present invention, even if the corrugated cardboard expands and contracts in response to environmental changes, damage to the corrugated cardboard caused by the resin band can be suppressed, and the bending of the resin band can also be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] External view of a large machine in its packaged state, packaged using the packaging material of Example 1. [Figure 2] Cross-sectional view of the top of the packaging box in Example 1. [Figure 3] Cross-sectional views of the top caps of the comparative example and Example 1. [Figure 4] A diagram showing an example of the storage conditions of the packaging boxes from Example 2 within the warehouse. [Figure 5] A graph showing an example of measured values ​​for the change in corrugated cardboard thickness over time when a load is applied. [Modes for carrying out the invention]

[0012] The following describes an embodiment of the packaging material of the present invention with reference to the drawings. [Examples]

[0013] First, the packaging material 1 according to Embodiment 1 of the present invention will be described using Figures 1 to 3.

[0014] Figure 1 is an external view of a large machine 2 (hereinafter referred to as "packaging box 3") in its packaged state, packaged with the packaging material 1 of this embodiment. In the following, the directions of up, down, front, back, left, and right 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 first-grade corrugated cardboard packaging materials. The top surface of the large machine 2 is covered with a top cap 13, which is second-grade corrugated cardboard packaging material. Then, two resin bands 14 are wrapped vertically along the front, top, rear, and bottom surfaces of the packaging box 3, thereby forming a packaging box 3 that integrates the base 11, side covers 12, and top cap 13.

[0016] Figure 2 is a cross-sectional view of the top of the packaging box 3 under certain conditions. Note that Figure 2 is a conceptual diagram primarily intended to explain the distance from the top edge of the side cover 12 to the top surface of the top cap 13 (hereinafter referred to as "clearance x"), and therefore the dimensional ratios of the parts shown in the figure do not necessarily correspond to the actual dimensional ratios.

[0017] As shown in Figure 2, the top cap 13 has a horizontal section 13a and a vertical section 13b. The horizontal section 13a also serves as a protective material for the upper part of the large machine 2, and is therefore constructed of thick, two-layer corrugated cardboard to enhance cushioning. Furthermore, a recess shaped to fit the upper part of the large machine 2 is pre-formed in the center of the lower surface of the horizontal section 13a to suppress horizontal sliding of the top cap 13. On the other hand, the vertical section 13b, which is not intended to come into contact with the large machine 2, is made of thin, single-layer corrugated cardboard and is positioned to come into contact with the inner surface of the side cover 12.

[0018] In a reference environment of normal temperature and low humidity (for example, an environment with 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 during the design of the packing box 3. However, since the clearance x increases or decreases according to the humidity, if the clearance x0 at the time of design is inappropriate, the cardboard may be damaged at the contact part with the resin band 14 during the expansion of the cardboard 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] <Influence of cardboard expansion> As described above, cardboard has the property of expanding when it contains moisture. Therefore, the cardboard will expand in a high-humidity environment and shrink in a low-humidity environment. This property becomes more prominent as the size of the cardboard increases. For example, in the case of the side cover 12 with a total height H of 2100 mm in the reference environment, when the cardboard elongation rate in a high-humidity environment is 1%, a large elongation exceeding 20 mm will occur.

[0020] Here, as a result of the expansion of each cardboard in FIG. 2, if the upper end of the side cover 12 extends above the upper surface of the top cap 13 (if the clearance x < 0), the contact mode between the upper side of the resin band 14 and the cardboard will shift from the mode of line contact with the upper surface of the top cap 13 to the mode of point contact with the upper end of the side cover 12. In that case, as a reaction force to the force by which the upper end of the side cover 12 pushes up the upper side of the resin band 14, the upper side of the resin band 14 will push down the upper end of the side cover 12, so there is a possibility of damage to the cardboard at the upper end of the side cover 12, which has lower strength than the 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 based on the maximum elongation of the total height H of the side cover 12.

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

[0023] In the comparative example top cap 13' shown in Figure 3(a), the vertical front surface and the horizontal top surface are directly connected, and the horizontal top surface and the vertical rear surface are also directly connected. If this configuration is adopted, when the resin band 14 is tightened as shown in Figure 1, stress from the resin band 14 will concentrate at the front and rear corners of the top cap 13', potentially causing the front and rear corners to collapse.

[0024] Therefore, in the top cap 13 of this embodiment shown in Figure 3(b), a bevel (hereinafter referred to as "corner cut") is provided at the front and rear corners, and the stress generated at the front and rear corners of the top cap 13 when the resin band 14 is tightened is distributed, thereby suppressing the occurrence of crushing at the front and rear corners. Although Figure 3(b) illustrates a configuration in which corner cuts are provided at the front and rear corners of the top cap 13, a curved surface with a predetermined curvature may be placed instead of the corner cut.

[0025] If the configuration shown in Figure 3(b) is adopted, the upper end position of the side of the top cap 13 will be moved downward by the distance L shown in the figure compared to the upper end position of the side of the top cap 13' in the comparative example. As the position of the upper end of the side of the top cap 13 is lowered in this way, the distance between the upper end of the side of the side of the top cap 13 and the upper end of the side of the side of the top cap 13 will be reduced. Therefore, in a high-humidity environment, the upper end of the side of the side of the side of the side of the side of the side of the side of the side of the top cap 13 will be more likely to exceed the upper end of the side of the top cap 13, and for the same reasons as above, the resin band 14 may damage the cardboard at the upper end of the side of the side of the side of the side of the side of the side of the top cap 12.

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

[0027] <Method for determining clearance x0 under standard environmental conditions> As described above, the reasons why the cardboard at the upper end of the side cover 12 is damaged by the resin band are thought to be that, in a high-humidity environment, the upper end of the side cover 12 extends upward, causing it to exceed the upper side edge of the top cap 13, and that the corner cuts in the top cap 13 cause the upper end of the side cover 12 to exceed the upper side edge of the top cap 13.

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

[0029] x0 > A+B ··· (Equation 1) Element A is the value obtained by multiplying the total height H of the side cover 12 by the elongation rate of the corrugated 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 the side cover 12 is 2100 mm, the expansion rate of the corrugated cardboard when moved from a standard environment to a high-humidity environment is 1%, and the height (distance L) of the corner cut of the top cap 13 is 10 mm, then setting the clearance x0 to be greater than 31 mm will prevent the upper edge of the side cover 12 from exceeding the upper side edge of the top cap 13, even in a high-humidity environment. This will prevent situations where the resin band 14 damages the corrugated cardboard at the upper edge of the side cover 12, or where the resin band 14 bends after the corrugated cardboard is damaged. [Examples]

[0031] Next, the packaging material 1 of Example 2 of the present invention will be described using Figures 4 and 5. Note that common points with Example 1 will be omitted from the explanation.

[0032] Figure 4 shows an example of the storage situation of packaging boxes 3 in a warehouse. In this example, in order to improve the storage efficiency of the warehouse, packaging boxes 3 are stacked up to three high using a forklift 4, etc. When packaging boxes 3 are stacked three high, the top surface of the bottom packaging box 3 (horizontal part 13a of the top cap 13) bears the weight of the two upper packaging boxes 3 (approximately 200 kg if the large machine 2 is a hot water storage unit for a water heater). Here, corrugated cardboard has the characteristic that if it is subjected to a load exceeding a certain amount for an extended period, the core placed between the liners will gradually collapse, and the thickness will gradually decrease.

[0033] Figure 5 shows a two-layer corrugated cardboard box with a thickness of 8 mm when unloaded, under a rated load of 625 kg / m². 2 This graph shows an example of the measured change in corrugated cardboard thickness over time when a load equivalent to the maximum load applied to the top cap 13 of the bottom packing box 3 in Figure 4 is continuously applied. The dashed line in the figure shows an approximate graph of the change in corrugated cardboard thickness over time under low humidity conditions (temperature 55°C, humidity 30%), and the double dashed line shows an approximate graph of the change in corrugated cardboard thickness over time under high humidity conditions (temperature 20°C, humidity 90%).

[0034] Under the low-humidity environment (Environment 1), the expansion of the cardboard is small, while under the high-humidity environment (Environment 2), the expansion of the cardboard is large. As shown in the figure, the initial thickness of the top cap 13 is greater under Environment 2 than under Environment 1. However, after a sufficient number of days (e.g., 37 days) have passed under load, the top cap thickness converges to approximately the same level under 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 the thickness of the top cap 13.

[0035] Therefore, in this embodiment where stacking of packaging boxes 3 is planned, the clearance x0 under standard conditions is set considering the limit to which the top cap 13 can become thinner. Specifically, in addition to elements A and B listed in Equation 1, element C, which is the maximum value of the reduction in the thickness of the top cap when a rated load is applied to the top cap 13, is also considered, and the clearance x0 is set by Equation 2.

[0036] x0 > A+B+C ··· (Equation 2) For example, if the total height H of the side cover 12 is 2100 mm, the elongation rate of the corrugated cardboard when moved from a standard environment to a high-humidity environment is 1%, the height of the corner cut of the top cap 13 is 10 mm, and the maximum design thickness reduction of the top cap 13 is 4 mm, then setting the clearance x0 to be greater than 35 mm will prevent the top edge of the side cover 12 from exceeding the top edge of the side of the top cap 13, even in a high-humidity environment and under the stacking conditions of the packaging boxes. This will prevent situations where the resin band 14 damages the corrugated cardboard at the top edge of the side cover 12, or where the resin band 14 bends after the corrugated cardboard is damaged. [Examples]

[0037] Next, we will describe the packaging material 1 of Example 3 of the present invention. Note that we will omit redundant explanations of points common to Example 2.

[0038] A certain degree of manufacturing tolerance is allowed in the overall height H of the corrugated cardboard side cover 12. For example, if the tolerance for the overall height H is ±10 mm, the upper end position of the side cover 12 may move up to 10 mm higher than the design value, and the upper end of the side cover 12 and the upper surface of the top cap 13 may be closer than the design value (see Figure 2).

[0039] Therefore, in this embodiment, which allows for manufacturing tolerances of the packaging box 3, the clearance x0 is set by Equation 3, which takes into account not only elements A, B, and C listed in Equation 2 of Embodiment 2, but also element D, which is the tolerance for the total height H of the side cover 12.

[0040] x0 > A+B+C+D ··· (Equation 3) For example, if the total height H of the side cover 12 is 2100 mm, the elongation rate of the corrugated cardboard when moved from a standard environment to a high-humidity environment is 1%, the height of the corner cut of the top cap 13 is 10 mm, the maximum design thickness reduction of the top cap 13 is 4 mm, and the allowable error of the total height H of the side cover 12 is ±10 mm, then by setting the clearance x0 to be greater than 45 mm, even under the conditions of a high-humidity environment, a stacked environment for packaging boxes, and the maximum allowable error of the total height H, the upper edge of the side cover 12 will not exceed the upper side edge of the top cap 13. This avoids situations where the resin band 14 damages the corrugated cardboard at the upper edge of the side cover 12, or where the resin band 14 bends after the corrugated 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 boxes 4 Forklift

Claims

1. Packing material for packaging large machinery, A base on which the aforementioned large machine is placed, A cardboard side cover enclosing the side of the aforementioned large machine, A cardboard top cap that covers the top of the aforementioned large machine, A resin band that is wrapped vertically around the base, the side cover, and the top cap, 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 which is a slope connecting the horizontal portion and the vertical portion. A packaging material characterized in that the clearance x0, which is the distance from the upper end of the side cover to the upper surface of the top cap in an environment with a temperature of 55°C and a humidity of 30%, is set by the following formula. x0 > A+B... (Formula 1) A is the value obtained by multiplying the total height of the side cover by the elongation rate of the corrugated cardboard in an environment with a temperature of 20°C and a humidity of 90%. B is the height of the corner cut on the top cap.

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

3. In the packaging material described in claim 2, A packaging material characterized in that the clearance x0 is set by the following formula. x0 > A+B+C+D... (Formula 3) D is the maximum tolerance for the total height of the side cover.

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

Images