PRODUCTION METHOD FOR PULP FOAM CUSHIONING MATERIAL, SHAPING MOLD FOR THE SAME, AND PULP FOAM CUSHIONING MATERIAL

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2024-076224 filed on May 9, 2024, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract.

TECHNICAL FIELD

The present specification discloses a method for producing a pulp foam cushioning material used as a buffer material, a shaping mold for molding a pulp foam cushioning material, and a pulp foam cushioning material.

BACKGROUND

Buffer materials, being molded pulp foam cushioning materials, are disclosed, for example, in JP 3017716 B, JP 3038158 B, JP 3125351 B, JP 3240664 B, JP 3240676 B, and JP 3278922. In a process of producing a pulp foam cushioning material, for example, a pulp feedstock composed of shredded pieces of pulp is mixed and kneaded with water and a foaming material by means of a mixer or the like. A foamy substance obtained by kneading is filled into a mold. As the mold, a metallic mold is used, for example. The foamy substance filled into the mold is dehydrated to obtain a porous pulp foam cushioning material.

In this regard, when there are variations in dehydrated conditions among regions of a foamy substance, the foamy substance may exhibit a nonuniform distribution of porosities. With this in view, the present specification discloses a production method of a pulp foam cushioning material in which nonuniformly dehydrated regions are reduced from those in related art, and discloses a shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material molded using the shaping mold.

SUMMARY

The present specification discloses a production method for a pulp foam cushioning material. The production method includes the steps of mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance, filling a shaping mold with an amount of the foamy substance that is greater than a volume of a pulp foam cushioning material, compressing the filled foamy substance, and dehydrating and drying the foamy substance. The shaping mold includes a mold main body which is entirely composed of a breathable material. In the drying step, the foamy substance is dehydrated and dried in a state where the mold main body surrounds all surfaces of the foamy substance.

According to the above-described configuration, the mold main body is, in its entirety, composed of the material having an air permeable property. Therefore, the foamy substance can be dehydrated through the entire surface of the mold main body. Further, according to the above-described configuration, the foamy substance is filled into the shaping mold to the amount greater than the volume of the pulp foam cushioning material, and compressed in the shaping mold. This allows the foamy substance to be in contact with the mold main body composed of the breathable material throughout the entire inner surface of the mold main body.

In the above-described configuration, a step of inserting a mesh panel between the shaping mold and the foamy substance may be included between the filling step and the compressing step.

According to the above-described configuration, a mesh pattern of the mesh panel can be transferred to a surface of the pulp foam cushioning material. In other words, the surface of the pulp foam cushioning material can be formed as a design surface.

The present specification further discloses a shaping mold for a pulp foam cushioning material. The shaping mold is filled with a foamy substance. The foamy substance is produced by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent. The shaping mold for a pulp foam cushioning material includes a mold main body. The mold main body is entirely composed of a breathable material.

According to the above-described configuration, the mold main body is entirely composed of the breathable material. Therefore, the foamy material can be dehydrated through the entire surface of the mold main body.

In the above-described configuration, the mold main body may be formed of flexible members. In this case, the shaping mold for the pulp foam cushioning material includes an external frame unit. The external frame unit supports the shape of the mold main body from its outside.

According to the above-described configuration, because the mold main body is formed of the flexible members, the flexible members will be deformed when an excessive pressure is applied to the foamy substance. In this way, flexibility of the pulp foam cushioning material can be ensured. In addition, because the external frame unit is provided, an easily deformable shape of the mold main body is supported from outside.

Further in the above-described configuration, the mold main body may be composed of a plurality of divided sub parts.

According to the above-described configuration, in contrast to the mold main body formed as one unit, releasability is improved.

In the above-described configuration, the plurality of sub parts may include a cross-shaped component and a columnar component. The cross-shaped component includes cross walls. The cross walls divide the pulp foam cushioning material into four portions. Further, a through hole is formed at the center of the cross walls. The columnar component is inserted into the through hole.

According to the above-described configuration, breathability of the mold main body is improved when the columnar component is removed from the through hole in a process of dehydrating the foamy substance.

Further, in the above-described configuration, the mold main body may include outer wall components, a first lid component, and a second lid component. The outer wall components surround the cross-shaped component. Further, the outer wall components are longer than the cross-shaped component. The first lid component is inserted into a filling space surrounded by the outer wall components, so as to be placed on the cross-shaped component. The second lid component is thicker than the first lid component and stacked on the first lid component. After the filling space is filled with the foamy substance, the foamy substance is downwardly pushed in by both the second lid component and the first lid component. Then, the second lid component is removed after the foamy body is pushed in.

According to the above-described configuration, because a thick lid consisting of the first lid component and the second lid component is used when the foamy substance is pushed in, the pressure applied to the foamy substance is rendered uniform. In addition, breathability in an upper portion of the mold main body can be ensured by removing the second lid component after the foamy substance is pushed in.

Still further, in the above-described configuration, the first lid component may have a water absorbing property superior to that of the cross-shaped component and the outer wall components.

According to the above-described configuration, the first lid component has a greater power of holding the foamy substance than that of the cross-shaped component and the outer wall components. Therefore, the first lid component can help the foamy substance to resist gravitational attraction, and thus can hinder the foamy substance from sagging. As a result, a surface conforming to the shape of the first lid component can be molded.

Further, in the above-described configuration, the shaping mold may be equipped with a filling mechanism disposed above the mold main body and the external frame unit. The filling mechanism includes a sleeve and a piston. The sleeve is configured to fill the foamy substance into the mold main body from thereabove. The piston is inserted into the sleeve. The sleeve is formed of a water impermeable material. In addition, the inner wall surface of the sleeve is a smooth surface.

When a portion of the foamy substance is spilled out of the mold main body, the spilled portion of the foamy substance will become fins or burrs after drying. According to the above-described configuration, however, because the inner wall surface of the sleeve is water impermeable and smooth, it is difficult for the foamy substance to remain within the sleeve. This can prevent the creation of fins or burrs.

In the above-described configuration, the shaping mold may include a mesh panel configured to be inserted between the cross-shaped component and the first lid component.

According to the above-described configuration, a mesh pattern of the mesh panel can be transferred to a surface of the pulp foam cushioning material. In order words, the surface of the pulp foam cushioning material can be formed as a design surface.

The present specification further discloses a pulp foam cushioning material. The cushioning material is produced by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance, and drying the foamy substance. The pulp foam cushioning material includes a core layer being a foamed layer, and a skin layer covering all surfaces of the core layer. A density of fibers in the skin layer is higher than a density of fibers in the core layer.

According to the above-described configuration, all surfaces of the core layer having flexibility and a cushioning property are covered by the skin layer having the relatively higher density of fibers. As a result, decomposition or exfoliation of the core layer can be suppressed.

In the above-described configuration, the pulp foam cushioning material includes a bottom wall and a plurality of side walls. The plurality of side walls extend upward from the bottom wall and are separated from each other. The bottom wall and the plurality of side walls define a central hole. Each of the bottom wall and the side walls includes a core layer being the foamed layer and a skin layer covering the core layer. In addition, the core layer in each of the side walls has a cushioning property superior to that of the core layer in the bottom wall.

According to the above-described configuration, a commodity housed in the central hole is mainly retained by the side walls of the pulp foam cushioning material. In this way, the commodity having a side area greater than a bottom area is reliably retained by the pulp foam cushioning material.

In the above-described configuration, a density of fibers in the core layer of the bottom wall may be higher than a density of fibers in the core layer of the side wall.

According to the above-described configuration, the core layer of the bottom wall is hardly dented or depressed, and the commodity is prevented from sinking in the bottom wall. As a result, the commodity retained by the side walls is constrained so as not to move in a height direction of the side walls.

Further, in the above-described configuration, the side walls may be thicker than the bottom wall.

In this way, an allowance for crushing to a certain degree can be secured in the side walls.

The production method of a pulp foam cushioning material, the shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material produced using the shaping mold disclosed herein can provide an effect that unevenly dehydrated regions in the foamy substance can be reduced compared to those in related art.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an example of a process to create a foamy substance;

FIG. 2 is a perspective view showing an example of a pulp foam cushioning material produced using a shaping mold according to an embodiment;

FIG. 3 is an exploded perspective view showing an example of components of the shaping mold according to the embodiment;

FIG. 4 shows an example of an assembly process (1/2) to assemble a mold main body;

FIG. 5 shows an example of the assembly process (2/2) to assemble the mold main body;

FIG. 6 shows an example of a compression process performed after the foamy substance is loaded into the mold main body;

FIG. 7 shows an example of a drying process;

FIG. 8 is a perspective, partial cross section view showing an example of a cross-section structure of the pulp foam cushioning material according to the embodiment;

FIG. 9 is a perspective view showing an example state where a commodity is retained by the pulp foam cushioning material according to the embodiment;

FIG. 10 shows a partially sectioned structure for explaining an internal structure in the state shown in FIG. 9;

FIG. 11 is an exploded perspective view showing an example of components of a shaping mold according to another example of the embodiment;

FIG. 12 shows an example of the assembly process (1/2) to assemble a mold main body in a shaping mold according to the other example of the embodiment;

FIG. 13 shows an example of the assembly process (2/2) to assemble the mold main body in the shaping mold according to the other example of the embodiment; and

FIG. 14 shows an example of the compression process after the foamy substance is loaded into the mold main body of the shaping mold according to the other example of the embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a method for producing a pulp foam cushioning material, a shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material molded using the shaping mold will be explained according to an embodiment with reference to the drawings. Shapes, materials, the number of items, and numerical values explained below are presented by way of illustration, and may be changed as appropriate depending on specifications of the shaping mold and the pulp foam cushioning material. It should be noted that identical or equivalent components are identified by identical reference numerals throughout the drawings.

<General Structure of Shaping Mold>

A foamy substance 19 illustrated in FIG. 1 is filled into a mold main body 20 illustrated in FIG. 5. Then, as illustrated in FIG. 6, the filled foamy substance 19 is compressed by means of a first lid component 70 and a second lid component 80. Following this, as illustrated in FIG. 7, the mold main body 20 is placed in a dryer 110 in a state where the mold main body 20 is housed in an external frame unit 90. The foamy substance 19 is dehydrated within the dryer 110 to obtain a pulp foam cushioning material 100 as illustrated in FIG. 2.

<Production Process of Foamy Substance>

Referring to FIG. 1, ingredients of the foamy substance 19 include water 15, a pulp feedstock 16, and a foaming agent 17. The pulp feedstock 16 is obtained by shredding a pulp raw material, such as a corrugated cardboard, for example.

The foaming agent 17 is, for example, a surfactant. The foaming agent 17 may be formed of an ordinary household material in order to reduce the load on the environment and impact on the human body. For example, the foaming agent 17 may be formed of any one of laundry detergent, body soap, or shampoo.

Firstly, the water 15 and the pulp feedstock 16 are introduced into a mixer 10. For example, substantially equal volumes of the water 15 and the pulp feedstock 16 are introduced into the mixer 10. Then, the mixer 10 is closed by a lid 11 and subsequently actuated. In this way, the pulp feedstock 16 is kneaded with water 15 while being further shredded and pulverized. As a result, slurry 18 is obtained.

Secondly, the foaming agent 17 is added to the slurry 18. An amount of the foaming agent 17 may be approximately one-tenth of the amount of water 15, for example. After the addition of the foaming agent 17, the lid 11 is closed to actuate the mixer 10 again. The slurry 18 is kneaded with the foaming agent 17, and the foamy substance 19 is obtained. The foamy substance 19 is introduced into a shaping mold. The shaping mold includes the mold main body 20 and the external frame unit 90 shown in FIG. 3.

<Structure of Shaping Mold>

FIG. 3 shows an exploded perspective view of the shaping mold according to the embodiment. The shaping mold includes the mold main body 20 and the external frame unit 90. The mold main body 20 is, in its entirety, formed of a breathable material. Further, the mold main body 20 is composed of flexible members, for example. The mold main body 20 is formed of sponge, for example. In other words, the mold main body 20 is formed of a porous member in which spongin fibers constitute a netted structure.

The mold main body 20 is composed of a plurality of divided sub parts. For example, the mold main body 20 includes a base 30, a cross-shaped component 40, a columnar component 50, outer wall components 60A, 60B, 60C and 60D, a first lid component 70, and a second lid component 80.

The base 30 is a rectangular plate member. As illustrated in FIG. 4, the cross-shaped component 40 is placed on the base 30. The cross-shaped component 40 includes a square tube 42 and partition walls 41A, 41B, 41C and 41D.

The square tube 42 is disposed at the center of the cross-shaped component 40. A through hole 43 is formed through the square tube 42. Before the foamy substance 19 is introduced, as shown in FIG. 4, the columnar component 50 is inserted into the square tube 42. That is, the through hole 43 is closed by the columnar component 50.

The partition walls 41A, 41B, 41C, and 41D respectively extend forward, rearward, leftward, and rightward from the square tube 42. That is, the partition walls 41A, 41B, 41C, and 41D constitute cross walls. Further, the through hole 43 is formed at the center of the cross walls.

The partition walls 41A and 41C are disposed on opposite sides of the square tube 42. In addition, the partition walls 41B and 41D are disposed on opposite sides of the square tube 42. A distance W2 from an extreme end (farthest from the square tube 42) of the partition wall 41A to an extreme end of the partition wall 41C is equal to a width W1 of the base 30. In addition, a distance L2 from an extreme end of the partition wall 41B to an extreme end of the partition wall 41D is equal to a length L1 of the base 30.

The partition walls 41A, 41B, 41C, and 41D correspond to slits 102A, 102B, 102C, and 102D in the pulp foam cushioning material 100. In other words, the partition walls 41A, 41B, 41C, and 41D divide the pulp foam cushioning material 100 into four portions (side walls 101A, 101B, 101C, and 101D).

To improve releasability, upper edges (ends farthest from the base 30) of the partition walls 41A, 41B, 41C, and 41D are finished by R-processing. That is, the tops of the partition walls 41A, 41B, 41C, and 41D are formed in a round shape.

The outer wall components 60A, 60B, 60C, and 60D have a shape of the L letter in a top view. The outer wall components 60A, 60B, 60C, and 60D are longer than the cross-shaped component 40. In other words, the height of the outer wall components 60A, 60B, 60C, and 60D is greater than the height of the cross-shaped component 40. For example, the height of the outer wall components 60A, 60B, 60C, and 60D is twice the height of the cross-shaped component 40.

The outer wall components 60A, 60B, 60C, and 60D include L-shaped walls 61A, 61B, 61C, and 61D, respectively. Recesses 62A, 62B, 62C, and 62D are formed in lower regions on both ends (i.e., both wing tips) of the L-shaped walls 61A, 61B, 61C, and 61D. As shown in FIGS. 3 and 5, the recesses 62A and 62B engage an end region of the partition wall 41A. Similarly, the recesses 62B and 62C engage an end region of the partition wall 41B, and the recesses 62C and 62D engage an end region of the partition wall 41C. Further, the recesses 62A and 62D engage an end region of the partition wall 41D.

Referring to FIG. 5, an inner surface of the outer wall component 60D may be marked by a guideline 64. The guideline 64 is a datum line indicating a level to which a lid member 91 should be pushed in. The distance from the guideline 64 to the top surface of the cross-shaped component 40 is greater than the sum of thicknesses of the first lid component 70, the second lid component 80, and the lid member 91. That is, as can be seen from the presence of a clearance D1 shown in FIG. 6, when the lid member 91 is pushed to the level of the guideline 64, the bottom surface of the first lid component 70 is spaced from the top surface of the cross-shaped component 40. Such an empty space is filled with a portion of the foamy substance 19. The portion of the foamy substance 19 filled into the space constitutes a bottom wall 104 of the pulp foam cushioning material 100.

The first lid component 70 and the second lid component 80 are inserted into a filling space surrounded by the outer wall components 60A, 60B, 60C, and 60D. Specifically, after the mold main body 20 assembled in a state (an open state) shown in FIG. 5 is filled with the foamy substance 29, the top of the foamy substance 29 is covered by the first lid component 70 and the second lid component 80. The first lid component 70 and the second lid component 80 are stacked in that order, so that the first lid component 70 constitutes a lower layer and the second lid component 80 constitutes an upper layer. The first lid component 70 and the second lid component 80 are formed in the same shape as the shape of an opening defined by the outer wall components 60A, 60B, 60C and 60D. In addition, the second lid component 80 is designed to be thicker than the first lid component 70.

Moreover, a degree of water absorbency of the first lid component 70 is greater than a degree of water absorbency of any one of the base 30, the cross-shaped component 40, the columnar component 50, and the outer wall components 60A, 60B, 60C, and 60D. The first lid component 70 holds the foamy substance 19 on an upper side of the foamy substance 19. Because the degree of water absorbency of the first lid component 70 is greater than that of the other components in the mold main body 20, the first lid component 70 is able to hold the foamy substance 19 while resisting gravitational attraction. Further, because the first lid component 70 holds the foamy body 19 from above, a surface of the pulp foam cushioning material 100, being a finished product (more specifically, the surface of the bottom wall 104), has a plate shape similar to the shape of the first lid component 70.

For example, the first lid component 70 is formed of cellulose sponge, while, the base 30, the cross-shaped component 40, the columnar component 50, and the outer wall components 60A, 60B, 60C, and 60D are formed of urethane foam sponge.

Referring to FIG. 3, the whole external frame unit 90 is a net-like component. The external frame unit 90 has a higher degree of rigidity than the mold main body 20. For example, the external frame unit 90 is formed of plastic or metal. The external frame unit 90 supports the shape of the mold main body 20 from the outside thereof.

The external frame unit 90 includes a box-shaped mesh member 95 and the lid member 91. The box-shaped mesh member 95 includes a bottom wall 97 and a side wall 96 having four sides. The top of the box-shaped mesh member 95 is open. The mold main body 20 is assembled within the box-shaped mesh member 95, as illustrated in FIGS. 4, 5, and 6, and the foamy substance 19 is loaded therein. The size of the bottom wall 97 is equal to the size (W1×L1) of the base 30. The depth of the box-shaped mesh member 95 is equal to a value obtained by adding the height of the outer wall component 60 to the thickness of the base 30 and a predetermined margin.

The lid member 91 is a planar mesh member. That is, the lid member 91 is a mesh panel. Further, in the top view, the shape of the lid member 91 is identical to the shape of the first lid component 70 and the second lid component 80.

<Production Process of Pulp Foam Cushioning Material>

The base 30, the cross-shaped component 40, and the columnar component 50 are assembled in a state shown in FIG. 4 within the box-shaped mesh member 95. Further, as shown in FIG. 5, the cross-shaped component 40 is enclosed by the outer wall components 60A, 60B, 60C, and 60D. The mold main body 20 in the open state shown in FIG. 5 is filled with the foamy substance 19. Here, taking into account a decrease in volume due to compression, dehydration, and drying of the foamy substance 19, a filling amount [cm³] of the foamy substance 19 is greater than a volume of the pulp foam cushioning material 100.

The first lid component 70 is placed on the filled foamy substance 19. Further, the second lid component 80 is stacked on the first lid component 70. Still further, the lid member 91 of the external frame unit 90 is placed on the first lid component 70.

A human operator or a press machine presses the lid member 91. Until the lid member 91 reaches the guideline 64, the foamy substance 19 is downwardly pushed in by the first lid component 70 and the second lid component 80. While being pushed by both the first lid component 70 and the second lid component 80 that is thicker than the first lid component 70, the foamy substance 19 spreads and reaches all interior regions of the mold main body 20.

In addition, because the mold main body 20 is composed of the flexible members, the foamy substance 19 is prevented from getting excessively compressed. Specifically, when an excessive pressure is applied to the foamy substance 19, the mold main body 20 is deformed. For this reason, flexibility of the pulp foam cushioning material 100, being a finished product, can be ensured.

Moreover, the outside of the mold main body 20 is held by the external frame unit 90. Therefore, the external frame unit 90 prevents the mold main body 20 from swelling. In addition, when the foamy substance 19 is compressed, the density of fibers is increased on a boundary surface between the foamy substance 19 and the mold main body 20. In other words, a density of fibers on a surface of the mold main body 20 (the surface being in contact with the foamy substance 19) becomes higher than a density of fibers in an internal region of the foamy substance 19.

Fibers pushed toward the surface of the mold main body 20 are entangled with the surface of the mold main body 20 which is a porous component. Such an entangled state is maintained during a process of dehydration and drying, which leads to formation of a skin layer 106.

After the lid member 91 of the external frame unit 90 is pushed down to the level of the guideline 64, the lid member 91 is temporarily removed, and the second lid component 80 is also removed. Then, the lid member 91 is placed on the first lid component 70. The thicker second lid component 80 is removed before drying, to thereby secure breathability of the foamy substance 19, in particular, an upper region thereof, during the drying process.

The external frame unit 90, the mold main body 20, and the filled foamy substance 19 are housed in the dryer 110 (see FIG. 7). In the dryer 110, for example, its chamber is set at a negative pressure. The foamy substance 19 is sucked and dehydrated in the dryer 110. Because the mold main body 20 and the external frame unit 90 are formed of the breathable material throughout the entire region, dehydration can be performed uniformly. In other words, the foamy substance 19 can be uniformly dehydrated and dried when all surfaces of the foamy substance 19 are surrounded, during the process of dehydration and drying, by the mold main body 20 and the external frame unit 90 formed of the breathable material.

Here, the drying process may be divided into two steps. For example, the drying process may be divided into a first step and a latter step, and the shaping mold (the mold main body 20 and the external frame unit 90) may be removed from the dryer 110 between the first step and the latter step. Then, the mold main body 20 is removed from the box-shaped mesh member 95. Further, the base 30 is temporarily detached, to pull out the columnar component 50 from the cross-shaped component 40. Following this, the base 30 is reattached to the mold main body 20, and the mold main body 20 is housed in the box-shaped mesh member 95 again. Then, the lid member 91 is placed, and the shaping mold and the foamy substance 19 being in a semidried state are housed in the dryer 110 again. The latter step of the drying process is subsequently initiated. In the latter step, because the cross-shaped component 40 is hollowed at the center, air permeability is improved.

Upon completion of the latter step of the drying process, the shaping mold (the mold main body 20 and the external frame unit 90) is removed from the dryer 110. Following this, the mold main body 20 is pulled out from the external frame unit 90. At this point, the pulp foam cushioning material 100 is molded within the mold main body 20 in a state of being inverted from the position shown in FIG. 2.

The mold main body 20 is peeled off from the pulp foam cushioning material 100. The structure of the mold main body 20 composed of the plurality of sub parts contributes to excellent releasability. In addition, the mold main body 20 is formed of the flexible porous material, such as sponge. For this reason, the mold main body 20 is peeled off from the pulp foam cushioning material 100 while getting deformed.

For example, the first lid component 70, the outer wall components 60A, 60B, 60C, and 60D, the base 30, and the cross-shaped component 40 are peeled off from the pulp foam cushioning material 100 in succession. As a result, the pulp foam cushioning material 100 shown in FIG. 2 is obtained.

<Pulp Foam Cushioning Material>

FIG. 2 illustrates the pulp foam cushioning material 100 produced using the shaping mold according to the embodiment. Further, FIG. 8 illustrates a partial cross sectional perspective view of the pulp foam cushioning material 100. The pulp foam cushioning material 100 takes a shape transferred from the shaping mold. The pulp foam cushioning material 100 includes the bottom wall 104 and the side walls 101A, 101B, 101C, and 101D.

The bottom wall 104 is a plate member having a rectangular shape in the bottom view. The side walls 101A, 101B, 101C, and 101D extend linearly upward from the bottom wall 104. For example, each of the side walls 101A, 101B, 101C, and 101D has an L letter shape in the top view.

The side walls 101A, 101B, 101C, and 101D are spaced from each other by the slits 102A, 102B, 102C, and 102D. In addition, a central hole 103 is defined in a center region of the pulp foam cushioning material 100 by the side walls 101A, 101B, 101C, and 101D surrounding the center region. The central hole 103 extends from the top surfaces of the side walls 101A, 101B, 101C, and 101D to the top surface of the bottom wall 104.

The pulp foam cushioning material 100 is a buffer material and is designed to house an article of commerce within the central hole 103. That is, the central hole 103 is a housing space for the commodity. To house the commodity, the commodity is inserted into the central hole 103 while pushing the side walls 101A, 101B, 101C, and 101D further apart.

Referring to FIG. 8, the pulp foam cushioning material 100 has a cross-section structure including a skin layer 106 and core layers 105A, 105B, and 105C. The skin layer 106 is a thin film layer in which the density of fibers is higher than that of the core layers 105A, 105B, and 105C. All surfaces of the pulp foam cushioning material 100 are covered with the skin layer 106.

As described above, when the pulp foam cushioning material 100 is molded, the foamy substance 19 is drawn toward its outer edges where the foamy substance 19 makes physical contact with the mold main body 20 in the process of suction and dehydration of the foamy substance 19. Then, moisture in the foamy substance 19 is extracted through the mold main body 20. That is, the density of fibers is increased in the outer edges of the foamy substance 19 contacting the mold main body 20. As a result, the skin layer 106 is formed on the surfaces of the pulp foam cushioning material 100.

The core layers 105A, 105B, and 105C exhibit a low density of fibers, and have an easily flakable form, which will be described below. The flaking of the core layers 105A, 105B, and 105C can be suppressed by covering all surfaces of the core layers 105A, 105B, and 105C with the skin layer 106.

The core layers 105, 105B, and 105C are foamed layers having a cushioning property. Referring to FIG. 8, in the pulp foam cushioning material 100, the core layers 105A, 105B, and 105C have different densities of fibers (i.e., different expansion ratios).

The core layer 105A constitutes the internal structure of the side walls 101A, 101B, 101C, and 101D. The core layer 105A exhibits the lowest density of fibers (highest expansion ratio) among those of the core layers 105A, 105B, and 105C. In other words, the core layer 105A has the best cushioning property among the core layers 105A, 105B, and 105C. A thickness T1 of the side walls 101A, 101B, 101C, and 101D is greater than a thickness T2 of the bottom wall 104. That is, the side walls 101A, 101B, 101C, and 101D include the core layer 105A having excellent cushioning property and sufficient thickness.

The core layer 105C constitutes the internal structure of the bottom wall 104. The core layer 105C exhibits the highest density of fibers (lowest expansion ratio) among those of the core layers 105A, 105B, and 105C. That is, the core layer 105C has the poorest cushioning property among the core layers 105A, 105B, and 105C. In other words, the core layer 105C is most resistant to being crushed, among the core layers 105A, 105B, and 105C.

The core layer 105B is formed in a joint region between the bottom wall 104 and each of the side walls 101A, 101B, 101C, and 101D. The density of fibers in the core layer 105B takes a value lying between the density of fibers in the core layer 105A and the density of fibers in the core layer 105C.

As described above with reference to FIG. 6, a portion of the foamy substance 19, the portion corresponding to the bottom wall 104, is pressurized by the first lid component 70, the second lid component 80, and the lid member 91 in the process of molding the pulp foam cushioning material 100. As a result, voids in the bottom wall 104 are compressed, and the density of fibers therein is accordingly decreased.

The pressurization is performed in order to spread the foamy substance 19 to reach all inner areas of the mold main body 20. Further, the pressurization is also performed for the purpose of fitting the shape of a bottom surface of the bottom wall 104 in the pulp foam cushioning material 100 to the shape of a bottom surface of an outer case 120 (see FIG. 9). For example, a lower surface of the first lid component 70 (the surface to be brought into contact with the foamy body 19) is formed in a shape conforming to the shape of the bottom surface of the outer case 120.

FIGS. 9 and 10 show an example packaging style of a jar 125 using the pulp foam cushioning material 100 according to the embodiment. The pulp foam cushioning material 100 internally retains the jar 125. For example, the height of the jar 125 is lower than the height of the side walls 101A, 101B, 101C, and 101D.

The pulp foam cushioning material 100 retaining the jar 125 is inserted into the outer case 120. During such an insertion process, inner walls of the side walls 101A, 101B, 101C, and 101D are depressingly deformed by the jar 125. Because the side walls 101A, 101B, 101C, and 101D are thicker than the bottom wall 104, an allowance for crushing to a certain degree can be secured in the core layer 105A.

As a result of depressing deformation of the side walls 101A, 101B, 101C, and 101D, the side walls 101A, 101B, 101C, and 101D are rendered in a hook shape as illustrated in FIG. 10. The side walls 101A, 101B, 101C, and 101D rendered in the hook shape can function to prevent the jar 125 from slipping out of the pulp foam cushioning material 100.

In this way, the pulp foam cushioning material 100 according to the embodiment can retain the jar 125 through the deformation of the side walls 101A, 101B, 101C, and 101D having the cushioning properties superior to that of the bottom wall 104. In particular, the side walls 101A, 101B, 101C, and 101D can provide an excellent holding effect on the jar 125 having a side area broader than a bottom area.

Meanwhile, the cushioning property of the bottom wall 104 is inferior to that of the side walls 101A, 101B, 101C, and 101D, i.e., the bottom wall 104 is more resistant to crushing than the side walls 101A, 101B, 101C, and 101D, which restricts vertical movement of the jar 125. In other words, the jar 125 cannot easily sink into the bottom wall 104 of the pulp foam cushioning material 100, and is accordingly constrained from moving along the height of the side walls 101A, 101B, 101C, and 101D.

<Another Example of Shaping Mold>

FIG. 11 shows an exploded perspective view of a shaping mold according to another example of the embodiment. The shaping mold includes the mold main body 20, the external frame unit 90, and a filling mechanism 93. The mold main body 20 is entirely formed of a breathable material. Further, the mold main body 20 is composed of a flexible member, for example. The mold main body 20 is formed of sponge, for example. That is, the mold main body 20 is composed of a porous member in which spongin fibers constitute a netted structure.

As a configuration different from the mold main body 20 shown in FIG. 3, the mold main body 20 of FIG. 11 includes a piston 92 (which will be described below) in place of the second lid component 80. The mold main body 20 of FIG. 11 further includes outer wall components 160A˜160D. The length of the outer wall components 160A˜160D is smaller than that of the outer wall components 60A˜60D in FIG. 3. For example, upper portions located above recesses 162A˜162D in the outer wall components 160A˜160D are defined to have a height equal to the thickness of the bottom wall 104 of the pulp foam cushioning material 100.

The external frame unit 90 includes a lid member 191 and a box-shaped mesh member 195. As a feature different from the external frame unit 90 of FIG. 3, the lid member 191 is smaller than the lid member 91 of FIG. 3. For example, the lid member 191 is formed identical in shape to an opening 94A of a sleeve 94. In addition, the lid 191 member is formed of a flexible material to ensure releasability from the pulp foam cushioning material 100.

Still further, as a configuration different from the external frame unit 90 of FIG. 3, the box-shaped mesh member 195 is formed of a metal material, such as aluminum, for example. The box-shaped mesh member 195 includes side walls 196 and a bottom wall 197, and the top of the box-shaped mesh member 195 is open. The side walls 196 and the bottom wall 197 are formed of punched metal sheets.

The filling mechanism 93 includes the piston 92 and the sleeve 94. Both the piston 92 and the sleeve 94 are formed of a water impermeable material. For example, the piston 92 and the sleeve 94 are formed of a metal material such as aluminum, for example.

The sleeve 94 may be formed in the shape of a square tube. The opening 94A of the sleeve 94 may have the same shape and size as the shape and size of an opening 161 (see FIG. 12) formed by the outer wall components 160A˜160D. The same size means that a lengthwise dimension and a breadthwise dimension of the opening 94A are equal to those of the opening 161.

An inner wall surface 94D (see FIG. 13) of the sleeve 94 is a slippery surface. For example, the inner wall surface 94D is mirror finished. As described above, the sleeve 94 is impermeable to water. Therefore, the inner wall surface 94D is a water-impermeable, smooth surface.

As will be described below, the foamy substance 19 is introduced into the sleeve 94. Due to the inner wall surface 94D of the sleeve 94 being the water-impermeable, smooth surface, the foamy substance 19 is prevented from remaining on the inner wall surface 94D. After the foamy substance 19 is dried, a portion of the foamy substance 19 that has escaped out of the mold main body 20 (see FIG. 13) becomes fins or burrs. Prevention of the presence of a residue of the foamy substance 19 on the inner wall surface 94D leads to suppression of the presence of fins or burrs.

The piston 92 includes a main body portion 92A and a gripping portion 92B. The main body portion 92A is inserted into the opening 94A of the sleeve 94. The shape of the main body portion 92A may be identical to the shape of the opening 94A. In addition, the piston 92 and the sleeve 94 are designed to establish a clearance of a predetermined value (such as, for example, 1 mm) or less between the opening 94A and the main body portion 92A.

For example, the piston 92 is of a solid structure including no cavity. The piston 92 is a heavy component having a weight of from 3 kg to 5 kg. In the process of compressively filling the foamy substance 19 into the mold body 20, the foamy substance 19 is filled into the mold main body 20 by the self-weight of the piston 92.

The gripping portion 92B is protruded from the main body portion 92A. The gripping portion 92B is designed to be gripped by a human operator to insert the piston 92 into the sleeve 94. Further, the gripping portion 92B also serves as a stopper for stopping further insertion of the piston 92.

Referring to FIG. 12, in a state where the cross-shaped component 40, the outer wall components 160A to 160D, and the base 30 are assembled in the mold main body 20, the mold main body 20 is housed in a box-shaped mesh member 195. As illustrated in FIG. 13, side walls 196 of the box-shaped mesh member 195 project upward from the upper end of the mold main body 20. The bottom wall 104 of the pulp foam cushioning material 100 is formed between the upper end of the mold main body 20 and upper ends of the side walls 196.

In addition, the filling mechanism 93 (see FIG. 11) is placed above the mold main body 20 and the box-shaped mesh member 195 of the external frame unit 90. Specifically, with reference to FIG. 13, the sleeve 94 is placed to rest on the box-shaped mesh member 195. In the placement process, a lower guide 94 guides the sleeve 94 so as to be aligned with the box-shaped mesh member 195.

Next, referring to FIG. 14, the foamy substance 19, which is not illustrated in the drawing, is introduced through the sleeve 94. As described above, an amount of the foamy substance 19 is introduced, the amount exceeding the volume of the pulp foam cushioning material 100. For example, the foamy substance 19 is introduced until it overflows within the sleeve 94.

Then, the lid member 191 and the first lid component 70 are placed over the opening 94A of the sleeve 94. The lid member 191 is a mesh panel as described above. The lid member 191 is sandwiched between the cross-shaped component 40 (see FIG. 12) of the mold main body 20 and the first lid component 70. Further, the lid member 191 is brought into contact with the foamy substance 19. As a result of the process of drying and dehydrating the foamy substance 19, a mesh pattern of the lid member 191 is transferred to a surface of the pulp foam cushioning material 100, the surface being in contact with the lid member 191. That is, the lid member 191 can be used to apply a design onto the surface of the pulp foam cushioning material 100.

Referring to FIG. 14, the lid member 191 and the first lid component 70 are housed in the sleeve 94. Further, the piston 92 is inserted into the sleeve 94. For example, the main body portion 92A is guided by an upper guide 94C on the sleeve 94 to enter the opening 94A. In the course of entry (sinking) of the piston 92 into the sleeve 94, due to the self-weight of the piston 92, the foamy substance 19 is compressed and fills the mold main body 20.

While being compressively filled, the foamy substance 19 experiences an event whereby the density of fibers on the boundary surface between the foamy substance 19 and the mold main body 20 becomes higher than the density of fibers in the internal region of the foamy substance 19. Because fibers are entangled with the mold main body 20 composed of the breathable porous material, a highly dense state of the fibers is maintained. In this state, the foamy substance 19 is dried and dehydrated, which leads to formation of the skin layer 106 on the surface of the pulp foam cushioning material 100.

It is obvious that the present disclosure is not limited to the above-described embodiment, and various changes and modifications may be made without departing from the scope of the technical idea of this disclosure defined in the accompanying claims.