JP7512144B2 - Porous structure and method for manufacturing the porous structure - Google Patents

Description

The present invention relates to a porous structure and a method for manufacturing a porous structure.

2. Description of the Related Art Conventionally, a porous structure having cushioning properties (such as urethane foam) has been produced through a process of foaming by chemical reaction, for example, in a mold molding process.
Meanwhile, in recent years, there have been proposals for porous structures that can be easily manufactured using a 3D printer to provide cushioning (for example, Patent Documents 1 and 2).

Publication No. WO2019/235544 Patent Publication No. WO2019/235547

However, the above-mentioned porous structure leaves room for improvement in terms of its ability to suppress wobbling for the user (hereinafter also referred to as "anti-wobbling performance").

The present invention aims to provide a porous structure capable of improving the anti-wobble performance, and a method for producing a porous structure capable of obtaining a porous structure capable of improving the anti-wobble performance.

The porous structure of the present invention is
A porous structure made of flexible resin or rubber,
The porous structure has a skeleton over almost the entirety thereof,
The skeleton portion is
A plurality of bones;
a plurality of connecting portions each connecting an end portion of the plurality of bone portions to each other;
It is equipped with
The porous structure is used for a cushioning material,
the porous structure has a plurality of cavities each of which is not open to an outer surface of the porous structure and is different from cell pores of the porous structure;
the plurality of cavities include a plurality of first cavities,
The multiple first hollow portions are arranged so that the closer the first hollow portion is to the center of a first region surrounded by the outer edges of the multiple first hollow portions on a projection plane of the cushioning material in a specified load input direction, the larger the volume of the first hollow portion is.
According to the porous structure of the present invention, the anti-wobble performance can be improved.

It is preferable that the portion of the porous structure that overlaps with the first region on the projection surface is configured so that the cross-sectional area of the bone portion that is closer to the center of the first region on the projection surface is smaller.
This can further improve the anti-wobble performance.

On the projection plane, the first region may be positioned so as to overlap with the center of the cushioning material in the left-right direction.

The porous structure is used as a cushion material for sitting,
In the projection plane, the first region may be positioned so as to overlap a portion of the cushion material immediately below one of the ischial bones of a seated occupant.

the plurality of cavities further includes a plurality of second cavities,
the second hollow portions are arranged such that a second hollow portion closer to a center of a second region surrounded by outer edges of the second hollow portions on the projection plane has a larger volume,
The first region and the second region may be configured not to overlap on the projection surface.

It is preferable that the portion of the porous structure that overlaps with the second region on the projection surface is configured so that the cross-sectional area of the bone portion that is closer to the center of the second region on the projection surface is smaller.
This can further improve the anti-wobble performance.

The porous structure is used as a cushion material for sitting,
On the projection plane, the first region and the second region may be positioned so as to overlap with a portion of the cushion material directly below a pair of ischial bones of a seated person.

It is preferable that the volume of each of the cavities is greater than the volume of the cell holes.
This can further improve the anti-wobble performance.

The porous structure is suitable for use in vehicle seat pads.

It is preferable that the porous structure is formed using a 3D printer.

The method for producing a porous structure of the present invention comprises the steps of:
The above-mentioned porous structure is manufactured using a 3D printer.
According to the method for producing a porous structure of the present invention, it is possible to obtain a porous structure capable of improving the wobble resistance performance.

The present invention provides a porous structure capable of improving the anti-wobble performance, and a method for producing a porous structure capable of obtaining a porous structure capable of improving the anti-wobble performance.

FIG. 1 is a perspective view showing a vehicle seat including an example of a cushioning material that may include a porous structure according to any embodiment of the present invention. 1 is a diagram showing a projection surface of a cushioning material having a porous structure according to a first embodiment of the present invention in a predetermined load input direction. FIG. 3 is a cross-sectional view of the cushioning material of FIG. 2 taken along the line DD in a predetermined load input direction; FIG. FIG. 4 is an enlarged view of part B in FIG. 3 . FIG. 5 is a cross-sectional view showing a cushioning material having a porous structure according to a second embodiment of the present invention, taken in a predetermined load input direction. FIG. 11 is a cross-sectional view showing a cushioning material including a porous structure according to a third embodiment of the present invention, taken in a predetermined load input direction. FIG. 13 is a diagram showing a projection surface of a cushioning material having a porous structure according to a fourth embodiment of the present invention in a predetermined load input direction. 8 is an E-E cross-sectional view showing the cushioning material of FIG. 7 cut along line E-E in a predetermined load input direction. FIG. FIG. 13 is a diagram showing a projection surface of a cushioning material having a porous structure according to a fifth embodiment of the present invention in a predetermined load input direction. 10 is a cross-sectional view taken along the line FF of FIG. 9, showing the cushioning material in a cross section taken in a predetermined load input direction. FIG. 13 is a cross-sectional view showing a cushioning material having a porous structure according to a sixth embodiment of the present invention, taken in a predetermined load input direction. FIG. 13 is a cross-sectional view showing a cushioning material having a porous structure according to a seventh embodiment of the present invention, taken in a predetermined load input direction. FIG. 1 is a diagram for explaining a method for producing a porous structure according to one embodiment of the present invention, which can be used to produce a porous structure according to any embodiment of the present invention. FIG. 2 is a perspective view showing an example of a cell structure that may be provided in a porous structure according to any embodiment of the present invention. 15 is a view taken along the arrow A in FIG. 14 showing the porous structure of FIG. 14 as viewed from the direction of the arrow A. FIG. FIG. 15 is a perspective view showing a cell partition of the porous structure of FIG. 14. FIG. 17 corresponds to FIG. 16 and is a diagram for explaining a modified example of the cell partition portion. FIG. 2 is a plan view showing another example of a cell structure that can be provided in a porous structure according to any embodiment of the present invention. 19(a) is a perspective view showing the bone portion of the porous structure of FIG. 18 when no external force is applied, and FIG. 19(b) is a perspective view showing the bone portion of FIG. 18(a) when an external force is applied.

The porous structure and the method for manufacturing the porous structure of the present invention can be used for cushioning materials for any purpose, but are particularly suitable for use in seat pads for any vehicle, and are particularly suitable for use in seat pads for vehicles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the porous structure and the method for producing the porous structure according to the present invention will be described with reference to the drawings.
In each drawing, the same components are denoted by the same reference numerals.

[Porous structure and cushioning material having a porous structure]
The porous structure 1 of each embodiment described in this specification can be used for cushioning materials for any purpose, but is preferably used for any vehicle seat pad, particularly for a vehicle seat pad. The porous structure 1 of each embodiment described in this specification may constitute the entire cushioning material 302, or may constitute only a part of the cushioning material 302.
The cushioning material 302 is configured so that a load is input from the user in a predetermined load input direction ID. In this specification, the "predetermined load input direction ID" is a direction that is preset as a direction in which a main load from the user is input to the cushioning material 302.

Below, the case where the porous structure 1 is used in a vehicle seat pad (hereinafter, simply referred to as a "seat pad"), which is an example of a cushioning material 302, will be described with reference to Figures 1 to 12. However, the porous structure 1 of each embodiment described in this specification can also be used in cushioning materials 302 other than vehicle seat pads.

FIG. 1 shows a vehicle seat 300 with an example of a cushioning material 302 that may comprise a porous structure 1 according to any embodiment of the present invention.
As shown by the broken line in FIG. 1, the vehicle seat 300 includes a cushion pad 310 for a seated person to sit on and a back pad 320 for supporting the back of the seated person. The cushion pad 310 and the back pad 320 are each made of a cushion material 302. The cushion pad 310 is the cushion material 302 for sitting on. In this example, the cushion material 302 is configured as a vehicle seat pad (seat pad). In addition to the cushion materials 302 constituting each of the cushion pad 310 and the back pad 320, the vehicle seat 300 can include, for example, a skin 330 that covers the front side (seater side) of the cushion material 302, a frame (not shown) that supports the cushion pad 310 from the bottom, a frame (not shown) that is installed on the back side of the back pad 320, and a headrest 340 that is installed on the upper side of the back pad 320 and supports the head of the seated person. The skin 330 is made of, for example, a breathable material (cloth, etc.). In the example of FIG. 1, the cushion pad 310 and the back pad 320 are configured as separate bodies, but may be configured as one body.
In addition, in the example of FIG. 1, the headrest 340 is configured separately from the back pad 320, but the headrest 340 may be configured integrally with the back pad 320.
In this specification, as shown in FIG. 1, the directions "up,""down,""left,""right,""front," and "rear" when viewed from a person seated in the vehicle seat 300 (and thus the cushion material 302) are simply referred to as "up,""down,""left,""right,""front," and "rear," respectively.

The cushion pad 310 has a main pad portion 311 configured to support the buttocks and thighs of a seated person from below, a pair of side pad portions 312 located on both the left and right sides of the main pad portion 311, raised higher than the main pad portion 311, and configured to support the seated person from both the left and right sides, and a back pad opposing portion 313 located behind the main pad portion 311 and configured to face the back pad 320.

The back pad 320 has a main pad portion 321 configured to support the back of the seated person from the rear, and a pair of side pad portions 322 located on both the left and right sides of the main pad portion 321, raised further forward than the main pad portion 321, and configured to support the seated person from both the left and right sides.

In this specification, the "extension direction LD of the cushion material 302" refers to a direction perpendicular to the left-right direction and thickness direction TD of the cushion material 302, and in the case of the cushion pad 310, refers to the front-back direction (FIG. 1), and in the case of the back pad 320, refers to the direction in which the main pad portion 321 extends from the lower surface to the upper surface of the main pad portion 321 of the back pad 320 (FIG. 1).
In addition, the "thickness direction TD of the cushion material 302" refers to the up-down direction in the case of the cushion pad 310 (Figure 1), and in the case of the back pad 320, it refers to the direction in which the main pad portion 321 of the back pad 320 extends from the surface (front surface) FS on the side of the seated person to the back surface BS (Figure 1).
Moreover, the "seater-side surface (front surface) FS" of the cushion material 302 refers to the upper surface in the case of the cushion pad 310 ( FIG. 1 ), and refers to the front surface in the case of the back pad 320 ( FIG. 1 ). The "back surface BS" of the cushion material 302 is the surface opposite to the seater-side surface FS of the cushion material 302, and refers to the lower surface in the case of the cushion pad 310 ( FIG. 1 ), and refers to the rear surface in the case of the back pad 320 ( FIG. 1 ). The "side surface SS" of the cushion material 302 is the surface between the seater-side surface FS and the back surface BS of the cushion material 302, and refers to any one of the front surface, rear surface, left surface, or right surface in the case of the cushion pad 310 ( FIG. 1 ), and refers to any one of the lower surface, upper surface, left surface, or right surface in the case of the back pad 320 ( FIG. 1 ).

The predetermined load input direction ID of the cushion material 302 coincides with the thickness direction TD of the cushion material 302 in both the cushion pad 310 and the back pad 320.

2 to 4 show a cushioning material 302 having a porous structure 1 according to the first embodiment of the present invention. The cushioning material 302 shown in FIGS. 2 to 4 is configured as a cushion pad 310. The porous structure 1 of this embodiment configures the entire cushioning material 302. FIG. 2 is a diagram showing a projection plane P in a predetermined load input direction ID of the cushioning material 302 having the porous structure 1 according to the first embodiment. Hereinafter, the projection plane P in a predetermined load input direction ID of the cushioning material 302 is also simply referred to as a "projection plane P". FIG. 3 is a cross-sectional view taken along line D-D in FIG. 2, showing the cushioning material in FIG. 2, cut in the predetermined load input direction along line D-D in FIG. 2. Line D-D in FIG. 2 is parallel to the left-right direction. FIG. 4 is an enlarged view of part B in FIG. 3.

The porous structure 1 has a large number of cell holes C (FIGS. 4 and 15). As described later, the porous structure 1 has a skeleton 2 over almost the entirety thereof, and the skeleton 2 has a plurality of bone portions 2B and a plurality of connecting portions 2J that connect the ends 2Be of the bone portions 2B to each other (FIGS. 4 and 15). The porous structure 1 is made of flexible resin or rubber.
Here, "flexible resin" refers to a resin that can be deformed when an external force is applied, and for example, an elastomer-based resin is preferable, and polyurethane is more preferable. Examples of rubber include natural rubber and synthetic rubber. Since the porous structure 1 is made of flexible resin or rubber, it can be compressed and restored in response to the application and release of an external force from a user, and therefore can have cushioning properties.
The porous structure 1 is preferably manufactured using a 3D printer, as will be described later with reference to FIG.
A suitable cell structure of the porous structure 1 will be described in detail later with reference to FIGS.

As will be described later with reference to FIG. 13, the porous structure 1 is preferably formed by a 3D printer.
By manufacturing the porous structure 1 using a 3D printer, the manufacturing process is simplified and the desired configuration can be obtained. In addition, with future technological advances in 3D printers, it is expected that manufacturing using a 3D printer will be possible in the future in a shorter time and at a lower cost. In addition, by manufacturing the porous structure 1 using a 3D printer, the configuration of the porous structure 1 corresponding to various required characteristics can be easily realized as desired.
In addition, when the porous structure 1 is manufactured using a 3D printer, a flexible resin or rubber is suitable as a material constituting the porous structure 1, and for example, a resin made of photocurable polyurethane (particularly ultraviolet curable polyurethane) can be used. As the photocurable polyurethane (particularly ultraviolet curable polyurethane), a resin made of urethane acrylate or urethane methacrylate can be used. Examples of such resins include those described in US Pat. No. 4,337,130.

As shown in Figures 2 to 4, the porous structure 1 has a number of cavities 6. Each of these cavities 6 is located inside the porous structure 1 and does not open to the outer surface of the porous structure 1. Furthermore, each of these cavities 6 is different from the cell holes C of the porous structure 1. As will be described later, the cell holes C of the porous structure 1 are defined by cell partitions 21 (Figure 4). On the other hand, the cavity 6, as illustrated in Figure 4, is not defined by the cell partitions 21, and is a hollow portion formed by the absence of part or all of one or more cell partitions 21.

2 and 3, the plurality of cavities 6 of the porous structure 1 include a plurality of first cavities 61. In this embodiment, the plurality of cavities 6 of the porous structure 1 include only the plurality of first cavities 61.
These first cavities 61 are located within a first area A1 surrounded by an outer edge E1 of the first cavities 61. No cavities 6 other than the first cavities 61 exist within the first area A1.
Here, "the outer edge E1 of the multiple first hollow portions 61" refers to a virtual surface that surrounds the multiple first hollow portions 61 collectively and contacts each of the multiple first hollow portions 61 that are located outermost among the multiple first hollow portions 61 when the multiple first hollow portions 61 are viewed as a group.
The plurality of first cavities 61 are non-uniform in volume. The plurality of first cavities 61 are arranged such that the first cavities 61 closer to the center A1C of the first region A1 on the projection plane P (FIG. 2) have a larger volume.
Here, "center A1C of first area A1" refers to the center of gravity (geometric center) of first area A1.
In addition, "the closer the first cavity 61 is to the center A1C of the first region A1 on the projection plane P, the larger the volume" means that, when viewed along each radial direction centered on the center A1C of the first region A on the projection plane P, the closer the first cavity 61 is to the center A1C, the larger the volume is, that is, when a plurality of first cavities 61 are arranged along the radial direction on the projection plane P, the volumes of the plurality of first cavities 61 gradually increase toward the center A1C. In this specification, "gradually increasing" is not limited to a case where the volume increases continuously without being constant in a part (in this case, the volumes of each pair of first cavities 61 adjacent to each other in the radial direction on the projection plane P are different), but also includes a case where the volume increases stepwise by being constant in a part (in this case, some pairs of first cavities 61 among each pair of first cavities 61 adjacent to each other in the radial direction on the projection plane P have the same volume).

In the first embodiment, as described above, the porous structure 1 has a plurality of cavities 6, and the plurality of cavities 6 include a plurality of first cavities 61, and the plurality of first cavities 61 are arranged so that the first cavities 61 closer to the center A1C of the first region A1 on the projection plane P have a larger volume. Therefore, the portion of the cushion material 302 that overlaps with the center side portion of the first region A1 on the projection plane P is more likely to bend than the portion that overlaps with the outer periphery side portion of the first region A1 on the projection plane P. Therefore, when the user applies a load to the cushion material 302 in the predetermined load input direction ID, the portion of the cushion material 302 that overlaps with the center side portion of the first region A1 on the projection plane P is more likely to bend (depress) than the portion that overlaps with the outer periphery side portion of the first region A1 on the projection plane P. As a result, the user is held by the portion of the cushion material 302 that overlaps with the outer periphery side portion of the first region A1 on the projection plane P, so that wobbling is suppressed. In this way, it is possible to improve the anti-wobble performance of the porous structure 1. This is particularly preferable when the porous structure 1 is used in a cushioning material to which vibration is input during use, for example, a seat pad for any vehicle, particularly a seat pad for a car.
Furthermore, according to this embodiment, the plurality of cavities 6 are not open to the outer surface of the porous structure 1, and therefore are not open to the surface of the cushion material 302, and therefore do not affect the touch feeling of the surface of the cushion material 302. Therefore, it is possible to avoid the presence of the cavities 6 from causing a sense of discomfort to the user.

In the porous structure 1 of the second to seventh embodiments described below, the porous structure 1 has a plurality of cavities 6, and these plurality of cavities 6 include a plurality of first cavities 61, and these plurality of first cavities 61 are arranged so that the first cavities 61 closer to the center A1C of the first region A1 on the projection plane P have a larger volume, and thus the same effect as in the first embodiment can be obtained.

In each embodiment described in this specification, the shape of each first cavity 61 may be any shape, for example, a sphere, an ellipsoid, a polyhedron (such as a rectangular parallelepiped), or the like, as shown in Figures 2 and 3. The shapes of each first cavity 61 may be the same as in the example of Figure 3, or may be different.

In each embodiment described in this specification, the positions of the centers of the first cavities 61 in the predetermined load input direction ID (and thus the thickness direction TD) may be arbitrary. The positions of the centers of the first cavities 61 in the predetermined load input direction ID (and thus the thickness direction TD) may be the same as in the example of FIG. 3 or may be different from each other.
Here, the “center of the cavity 6 (the first cavity 61 , the second cavity 62 described below)” refers to the center of gravity (geometric center) of the cavity 6 .

In each embodiment described in this specification, as in the examples of Figures 2 to 3, the multiple first hollow portions 61 may not overlap with each other on the projection plane P (i.e., the multiple first hollow portions 61 are not arranged along the specified load input direction ID).
Alternatively, in each embodiment described in this specification, the multiple first cavities 61 may overlap each other on the projection plane P.

In each embodiment described in this specification, as in the first embodiment shown in FIG. 3 and the fifth embodiment shown in FIG. 10, the cross-sectional area of the multiple bone parts 2B constituting the part G1 of the porous structure 1 overlapping with the first region A1 on the projection plane P may be uniform. Here, the cross-sectional area of the bone part 2B refers to the cross-sectional area of the cross section perpendicular to the skeleton line O (FIG. 15) of the bone part 2B, as described later. In this case, the density of the part G1 other than the multiple first cavities 61 (and thus the cell structure) is uniform. In this case, the cross-sectional area of the multiple bone parts 2B constituting the part of the porous structure 1 that does not overlap with the first region A1 on the projection plane P may be the same as or different from the cross-sectional area of the multiple bone parts 2B constituting the part G1 overlapping with the first region A1 on the projection plane P.

In each embodiment described in this specification, as in the second embodiment shown in Figure 5 and the sixth embodiment shown in Figure 11, the cross-sectional areas of the multiple bone portions 2B that constitute the portion G1 of the porous structure 1 that overlaps with the first region A1 on the projection plane P may be non-uniform.
In this case, as in the second embodiment shown in FIG. 5 and the sixth embodiment shown in FIG. 11, it is preferable that the portion G1 of the porous structure 1 overlapping with the first region A1 on the projection plane P has a smaller cross-sectional area as the bone portion 2B is closer to the center A1C of the first region A1 on the projection plane P. As a result, the portion of the cushion material 302 overlapping with the central portion of the first region A1 on the projection plane P is more likely to bend than the portion overlapping with the outer peripheral portion of the first region A1 on the projection plane P. As a result, the user is held more firmly by the portion of the cushion material 302 overlapping with the outer peripheral portion of the first region A1 on the projection plane P, so that wobbling is further suppressed. In this way, the wobbling resistance of the porous structure 1 can be further improved.
Here, "the closer the bone portion 2B is to the center A1C of the first region A1 on the projection plane P, the smaller the cross-sectional area" means that, when viewed along each radial direction centered on the center A1C of the first region A on the projection plane P, the closer the bone portion 2B is to the center A1C, the smaller the cross-sectional area is, that is, the cross-sectional areas of the multiple bone portions 2B arranged along the radial direction on the projection plane P gradually decrease toward the center A1C. In this specification, "gradually decreasing" is not limited to a case where the cross-sectional area decreases continuously without being constant in a part (in this case, the cross-sectional areas of each pair of bone portions 2B adjacent in the radial direction on the projection plane P are different), but also includes a case where the cross-sectional area decreases stepwise by being constant in a part (in this case, the cross-sectional areas of some pairs of bone portions 2B among each pair of bone portions 2B adjacent in the radial direction on the projection plane P are the same).
In this case, the cross-sectional areas of the multiple bone portions 2B constituting the portion G1 of the porous structure 1 that overlaps with the first region A1 on the projection plane P may each be uniform throughout the entire bone portion 2B, or may be non-uniform throughout the entire bone portion 2B, and may, for example, gradually decrease along the extension direction of the bone portion 2B (i.e., along the skeletal line O of the bone portion 2B) toward the center A1C of the first region A1 on the projection plane P.

In each embodiment described in this specification, the porous structure 1 may constitute the entire cushion material 302, as in the embodiments shown in Figs. 3, 5, 10, and 11.
Alternatively, in each embodiment described in this specification, the porous structure 1 may constitute only a part of the cushion material 302 as in each embodiment shown in FIG. 3, FIG. 5, FIG. 10, and FIG. 11, or the porous structure 1 may constitute only a part of the cushion material 302 as in each embodiment shown in FIG. 6, FIG. 8, and FIG. 12. This allows the size of the porous structure 1 to be reduced, and thus makes it possible to manufacture the porous structure 1 using a relatively small 3D printer. In that case, the part of the cushion material 302 other than the part constituted by the porous structure 1 (hereinafter referred to as the "main body 351") may be constituted by a conventional general porous structure (foam) as described above, for example, by being manufactured through a process of foaming by chemical reaction in mold molding or slab molding. In this case, for example, the main body 351 may have one or more recesses 350 as in each embodiment shown in FIG. 6, FIG. 8, and FIG. 12, and the porous structure 1 may be accommodated in each recess 350. In each embodiment of FIG. 6 and FIG. 12, the main body 351 has one recess 350, and one porous structure 1 is accommodated in this recess 350. In the embodiment of FIG. 8, a main body 351 has two recesses 350, and each recess 350 houses one porous structure 1 (two in total).
Alternatively, although not shown in the drawings, in each embodiment described in this specification, the cushion material 302 may be composed only of a plurality of porous structures 1. This also makes it possible to reduce the size of the porous structure 1, and thus makes it possible to manufacture the porous structure 1 using a relatively small 3D printer.

In each embodiment described in this specification, when the cushioning material 302 is configured as a cushion pad 310 as in each embodiment shown in Figures 2 to 12, it is preferable that the first area A1 overlaps with the main pad portion 311 on the projection plane P, and it is more preferable that the first area A1 overlaps only with the main pad portion 311 on the projection plane P. However, the first area A1 may also overlap with the side pad portion 312 on the projection plane P.

In each embodiment described in this specification, although not shown, the cushioning material 302 may be configured as a back pad 320 (FIG. 1). In this case, it is preferable that the first area A1 overlaps with the main pad portion 321 on the projection surface P, and it is more preferable that the first area A1 overlaps only with the main pad portion 321. However, on the projection surface P, the first area A1 may also overlap with the side pad portion 322.

In each embodiment described in this specification, as in each embodiment shown in Figures 2 to 3, 5, and 6, the first region A1 may be arranged to overlap the center 302C (Figure 2) in the left-right direction of the cushion material 302 on the projection plane P. This allows the user to be held more evenly on both the left and right sides by the portion of the cushion material 302 that overlaps with the outer peripheral portion of the first region A1 on the projection plane P, so that wobbling is more effectively suppressed. In this way, the wobbling resistance of the porous structure 1 can be further improved.
In this case, on the projection plane P, it is preferable that the center A1C of the first region A1 is positioned so as to overlap with the left-right center 302C of the cushioning material 302 as in the embodiment shown in Figure 2, but it may also be positioned at a position away from the left-right center 302C of the cushioning material 302.

In each embodiment described in this specification, as in each embodiment shown in Figures 7 to 12, the first region A1 may be arranged so as to overlap with a portion 303 of the cushion material 302 directly below one of the ischial bones of the seated person on the projection plane P. In this case, the porous structure 1 is used as the cushion material 302 for sitting (e.g., cushion pad 310). As a result, the user's ischial bones are held by the portion of the cushion material 302 that overlaps with the outer peripheral portion of the first region A1 on the projection plane P, so that wobbling is more effectively suppressed. In this way, the wobbling resistance of the porous structure 1 can be further improved.
In this case, as in the embodiments shown in Figures 7 to 12, it is preferable that the first area A1 is arranged so as not to overlap with the left-right center 302C of the cushion material 302 on the projection plane P.
In the embodiment of Figures 7 and 8, the cushion material 302 has two porous structures 1, and on the projection plane P, the first region A1 of one of the porous structures 1 is positioned so as to overlap with the portion 303 of the cushion material 302 directly below the ischial bone on the left side of the seated person, and the first region A1 of the other porous structure 1 is positioned so as to overlap with the portion 303 of the cushion material 302 directly below the ischial bone on the right side of the seated person.
As in each embodiment shown in Figures 7 and 9, it is preferable that, on the projection plane P, the center A1C of the first region A1 is positioned so as to overlap with the center of a portion 303 of the cushion material 302 directly below one of the ischial bones of the seated occupant.
In this specification, the portions 303 of the cushion material 302 directly below a pair of ischial bones of a seated person on the projection plane P are defined as a pair of portions of the cushion material 302 that receive the highest seating pressure on the projection plane P when a 3D mannequin (three-dimensional seated human body model for measuring automobile interior dimensions (3DM-JM 50)) defined in JIS D 4607 is seated on the seating portion of the cushion material 302 (e.g., main pad portion 311 of the cushion pad 310).

In each embodiment described in this specification, as in each embodiment of FIGS. 9 to 12, the multiple cavities 6 provided in the porous structure 1 may further include multiple second cavities 62.
These second cavities 62 are located within a second region A2 surrounded by an outer edge E2 of the second cavities 62. There are no cavities 6 other than the second cavities 62 within the second region A2. On the projection plane P, the first region A1 and the second region A2 are not overlapped.
Here, the "outer edge E2 of the multiple second hollow portions 62" refers to a virtual surface that surrounds the multiple second hollow portions 62 collectively and contacts each of the multiple second hollow portions 62 that are located outermost among the multiple second hollow portions 62 when the multiple second hollow portions 62 are viewed as a group.
The second cavities 62 are non-uniform in volume. The second cavities 62 are arranged such that the second cavities 62 closer to the center A2C of the second region A2 on the projection plane P have a larger volume.
With this configuration, the cushion material 302 is more likely to bend at the portion overlapping the center portion of the second region A2 on the projection plane P than at the portion overlapping the outer peripheral portion of the second region A2 on the projection plane P. Therefore, when a user applies a load to the cushion material 302 in a predetermined load input direction ID, the cushion material 302 is more likely to bend (depress) at the portion overlapping the center portion of the second region A2 on the projection plane P than at the portion overlapping the outer peripheral portion of the second region A2 on the projection plane P. As a result, the user is held by the portion of the cushion material 302 that overlaps the outer peripheral portion of the second region A2 on the projection plane P, thereby suppressing wobbling. In this way, the wobbling resistance of the porous structure 1 can be improved.
Here, the "center A2C of the second region A2" refers to the center of gravity (geometric center) of the second region A2.
Further, "the second cavity 62 closer to the center A2C of the second region A2 on the projection plane P has a larger volume" means that, when viewed along each radial direction centered on the center A2C of the second region A on the projection plane P, the second cavity 62 closer to the center A2C has a larger volume, that is, when a plurality of second cavities 62 are arranged along the radial direction on the projection plane P, the volumes of the plurality of second cavities 62 gradually increase toward the center A2C. Here, "gradual increase" is not limited to the case where the volume increases continuously without becoming constant in a part (in this case, the volumes of each pair of second cavities 62 adjacent to each other in the radial direction on the projection plane P are different), but also includes the case where the volume increases stepwise by becoming constant in a part (in this case, the volumes of some pairs of second cavities 62 among each pair of second cavities 62 adjacent to each other in the radial direction on the projection plane P are the same).

In each embodiment described in this specification, the shape of each second cavity 62 may be any shape, for example, a sphere, an ellipsoid, a polyhedron (such as a rectangular parallelepiped), or the like, as shown in Figures 9 to 12. The shapes of each second cavity 62 may be the same as in the examples of Figures 9 to 12, or may be different.

In each embodiment described in this specification, the position of the center of each second cavity 62 in the specified load input direction ID (and thus the thickness direction TD) may be arbitrary. The positions of the centers of each second cavity 62 in the specified load input direction ID (and thus the thickness direction TD) may be the same as in the examples of Figures 9 to 12, or may be different.

In each embodiment described in this specification, as in the examples of Figures 9 to 12, the multiple second hollow portions 62 may not overlap with each other on the projection plane P (i.e., the multiple second hollow portions 62 are not arranged along the specified load input direction ID).
Alternatively, in each embodiment described in this specification, the multiple second cavities 62 may overlap each other on the projection plane P.

In each embodiment described in this specification, as in the fifth embodiment shown in FIG. 10, the cross-sectional area of the multiple bone parts 2B constituting the portion G2 of the porous structure 1 that overlaps with the second region A2 on the projection plane P may be uniform. In this case, the density of the portion G2 other than the multiple second cavities 62 (and thus the cell structure) is uniform. In this case, the cross-sectional area of the multiple bone parts 2B constituting the portion of the porous structure 1 that does not overlap with the second region A2 on the projection plane P may be the same as or different from the cross-sectional area of the multiple bone parts 2B constituting the portion G2 that overlaps with the second region A2 on the projection plane P.

In each embodiment described in this specification, as in the sixth embodiment shown in Figure 11, the cross-sectional areas of the multiple bone portions 2B constituting the portion G2 of the porous structure 1 that overlaps with the second region A2 on the projection plane P may be non-uniform.
In this case, as in the sixth embodiment shown in FIG. 11, it is preferable that the portion G2 of the porous structure 1 overlapping with the second region A2 on the projection plane P has a smaller cross-sectional area as the bone portion 2B is closer to the center A2C of the second region A2 on the projection plane P. As a result, the portion of the cushion material 302 overlapping with the central portion of the second region A2 on the projection plane P is more likely to bend than the portion overlapping with the outer peripheral portion of the second region A2 on the projection plane P. As a result, the user is held more firmly by the portion of the cushion material 302 overlapping with the outer peripheral portion of the second region A2 on the projection plane P, so that wobbling is further suppressed. In this way, the wobbling resistance of the porous structure 1 can be further improved.
Here, "the closer the bone portion 2B is to the center A2C of the second region A2 on the projection plane P, the smaller the cross-sectional area" means that, when viewed along each radial direction centered on the center A2C of the second region A on the projection plane P, the closer the bone portion 2B is to the center A2C, the smaller the cross-sectional area, in other words, the cross-sectional area of the multiple bone portions 2B arranged along the radial directions on the projection plane P gradually decreases toward the center A2C.
In this case, the cross-sectional areas of the multiple bone portions 2B constituting the portion G2 of the porous structure 1 that overlaps with the second region A2 on the projection plane P may each be uniform throughout the entire bone portion 2B, or may be non-uniform throughout the entire bone portion 2B, and may, for example, gradually decrease along the extension direction of the bone portion 2B (i.e., along the skeletal line O of the bone portion 2B) toward the center A2C of the second region A2 on the projection plane P.

In each embodiment described in this specification, when the cushioning material 302 is configured as a cushion pad 310, as in each embodiment shown in Figures 9 to 12, it is preferable that the second area A2 overlaps with the main pad portion 311 on the projection plane P, and it is more preferable that the second area A2 overlaps only with the main pad portion 311. However, on the projection plane P, the second area A2 may also overlap with the side pad portion 312.

In each embodiment described in this specification, although not shown, the cushioning material 302 may be configured as a back pad 320 (FIG. 1). In this case, it is preferable that the second area A2 overlaps with the main pad portion 321 on the projection surface P, and it is more preferable that the second area A2 overlaps only with the main pad portion 321. However, on the projection surface P, the second area A2 may also overlap with the side pad portion 322.

In each embodiment described in this specification, as in each embodiment shown in FIG. 9 to FIG. 12, the second region A2 may be arranged so as to overlap with a portion 303 of the cushion material 302 directly below one of the ischial bones of the seated person on the projection plane P. In this case, as in each embodiment shown in FIG. 9 to FIG. 12, it is preferable that the first region A1 and the second region A2 are arranged so as to overlap with a portion 303 of the cushion material 302 directly below a pair of ischial bones of the seated person on the projection plane P. In this case, the porous structure 1 is used as a cushion material 302 for sitting (for example, a cushion pad 310). As a result, the user's pair of ischial bones are held by the portions of the cushion material 302 that overlap with the outer peripheral portions of the first region A1 and the second region A2 on the projection plane P, so that wobbling is more effectively suppressed. In this way, the wobbling resistance of the porous structure 1 can be further improved.
In this case, as in the embodiments shown in Figures 9 to 12, it is preferable that the second area A2 is arranged so as not to overlap with the left-right center 302C of the cushion material 302 on the projection plane P.
In each of the embodiments in Figures 9 to 12, on the projection plane P, the second area A2 is positioned so as to overlap with a portion 303 of the cushion material 302 directly below the ischial bone on the left side of the seated person, and the first area A1 is positioned so as to overlap with a portion 303 of the cushion material 302 directly below the ischial bone on the right side of the seated person.
As in the embodiment shown in Figure 9, it is preferable that, on the projection plane P, the center A1C of the second region A2 is positioned so as to overlap with the center of a portion 303 of the cushion material 302 directly below one of the ischial bones of the seated occupant.

In each embodiment described in this specification, it is preferable that the volume of each cavity 6 provided in the porous structure 1 is larger than the volume of the cell hole C (FIG. 4). This can further improve the wobble resistance.
However, the volume of some or all of the cavities 6 among the plurality of cavities 6 provided in the porous structure 1 may be equal to or smaller than the volume of the cell holes C.

[Method for producing a porous structure]
Next, a method for producing the porous structure 1 of the present invention will be described with reference to Fig. 13. The method described below is a method for producing the porous structure 1 using a 3D printer, and can be suitably used for producing the porous structure 1 of any embodiment described in this specification. Fig. 13 shows how the porous structure 1 of Fig. 3 is produced.
First, three-dimensional shape data (for example, three-dimensional CAD data) representing the three-dimensional shape of the porous structure 1 is created in advance using a computer.
Next, using a computer, the three-dimensional shape data is converted into 3D printing data 500. The 3D printing data 500 is read into the control unit 410 of the 3D printer 400 when the modeling unit 420 of the 3D printer 400 performs modeling, and the control unit 410 is configured to cause the modeling unit 420 to model the porous structure 1. The 3D printing data 500 includes, for example, slice data representing the two-dimensional shape of each layer of the porous structure 1.
Next, the porous structure 1 is modeled by a 3D printer 400. The 3D printer 400 may perform modeling using any modeling method, such as a photolithography method, a powder sintering lamination method, a fused deposition modeling (FDM) method, an inkjet method, etc. From the viewpoint of productivity, the photolithography method is preferable. FIG. 13 shows a state in which modeling is performed by the photolithography method.
The 3D printer 400 includes, for example, a control unit 410 configured by a CPU or the like, a modeling unit 420 that performs modeling under the control of the control unit 410, a support table 430 for placing a modeled object (i.e., the porous structure 1) to be modeled, and a container 440 that contains the liquid resin LR, the support table 430, and the modeled object. When the modeling unit 420 uses a photo-modeling method as in this example, it has a laser irradiator 421 configured to irradiate ultraviolet laser light LL. The container 440 is filled with the liquid resin LR. When the liquid resin LR is hit by the ultraviolet laser light LL irradiated from the laser irradiator 421, it hardens and becomes a flexible resin.
In the 3D printer 400 configured in this manner, the control unit 410 first reads the 3D modeling data 500, and then controls the modeling unit 420 to irradiate ultraviolet laser light LL based on the three-dimensional shape contained in the read 3D modeling data 500, thereby sequentially modeling each layer.
After the modeling by the 3D printer 400 is completed, the model is removed from the container 440. As a result, the porous structure 1 is finally obtained as the model.
By manufacturing the porous structure 1 using a 3D printer, a porous structure 1 having a plurality of cavities 6 can be realized simply, precisely and as desired in a single process.
When the porous structure 1 is made of resin, the porous structure 1 as a molded object may be heated in an oven after the molding by the 3D printer 400 is completed. In this case, the bonds between the layers constituting the porous structure 1 are strengthened, and the anisotropy of the porous structure 1 can be reduced, thereby further improving the cushioning properties of the porous structure 1.
Furthermore, when the porous structure 1 is made of rubber, the porous structure 1 as a molded object may be vulcanized after the molding by the 3D printer 400 is completed.

[Cell structure of porous structure]
Next, the portion (cell structure) of the above-mentioned porous structure 1 other than the cavity portion 6 will be described in detail with reference to Figures 14 to 19. The cell structure of the porous structure 1 described below can be used in the porous structure 1 according to any embodiment described in this specification.
14 to 17, in order to facilitate understanding of the orientation of the porous structure 1, the orientation of an XYZ orthogonal coordinate system fixed to the porous structure 1 is shown.

In Figures 14 and 15, a portion of the porous structure 1 having an approximately rectangular parallelepiped outer shape is viewed from different angles. Figure 14 is a perspective view showing that portion of the porous structure 1. Figure 15 is a view from the direction of arrow A showing that portion of the porous structure 1 in Figure 14 as viewed from the direction of arrow A (Y direction).

The porous structure 1 is shaped by a 3D printer. By manufacturing the porous structure 1 using a 3D printer, manufacturing is easier than in the conventional case where a foaming process is performed by chemical reaction, and the desired configuration can be obtained. Furthermore, with future technological advances in 3D printers, it is expected that in the future, manufacturing using 3D printers will be possible in a shorter time and at a lower cost. Furthermore, by manufacturing the porous structure 1 using a 3D printer, the configuration of the porous structure 1 that meets various required characteristics can be easily realized as desired.

As described above, the porous structure 1 is made of flexible resin or rubber.
From the viewpoint of ease of manufacturing using a 3D printer, it is more preferable for the porous structure 1 to be made of a flexible resin than of rubber.
From the viewpoint of ease of manufacturing using a 3D printer, it is preferable that the entire porous structure 1 is made of a material having the same composition, but the porous structure 1 may be made of materials having different compositions depending on the portion.

As described above, the porous structure 1 is formed by a 3D printer. The porous structure 1 is configured as a single unit in its entirety.
The porous structure 1 is made of a flexible resin or rubber. More specifically, the porous structure 1 includes a skeletal portion 2 that forms the skeleton of the porous structure 1. The skeletal portion 2 defines a large number of cell holes C. The skeletal portion 2 is present throughout almost the entire porous structure 1, and is made of a flexible resin or rubber. In this example, the portions of the porous structure 1 other than the skeletal portion 2 are voids, in other words, the porous structure 1 is made of only the skeletal portion 2.

14 to 16, the skeleton 2 of the porous structure 1 is composed of a plurality of bones 2B and a plurality of connecting portions 2J, and the entire skeleton 2 is integrally constructed. In this example, each bone 2B is formed in a columnar shape and extends linearly. Each connecting portion 2J connects end portions 2Be of a plurality of (e.g., four) bone portions 2B extending in different directions to each other at locations where these end portions 2Be are adjacent to each other in the extension direction.
14 to 16, the skeleton line O of the skeleton 2 is shown by a dashed line in a part of the porous structure 1. The skeleton line O of the skeleton 2 is composed of the skeleton line O of each bone portion 2B and the skeleton line O of each joint portion 2J. The skeleton line O of the bone portion 2B is the central axis of the bone portion 2B. The skeleton line O of the joint portion 2J is an extension line portion formed by smoothly extending the central axes of each bone portion 2B joined to the joint portion 2J into the joint portion 2J and connecting them to each other. The central axis of the bone portion 2B is a line connecting the centers of gravity of the shape of the bone portion 2B in a cross section perpendicular to the extension direction of the bone portion 2B at each point in the extension direction of the bone portion 2B.
The extending direction of the bone portion 2B is the extending direction of a skeleton line O of the bone portion 2B (a portion of the skeleton line O that corresponds to the bone portion 2B; the same applies below).
Since the porous structure 1 has the skeleton 2 over almost the entire surface thereof, it is possible for it to be compressed and restored in response to the application and release of an external force while ensuring breathability, and therefore has good characteristics as a cushioning material. In addition, the structure of the porous structure 1 is simple, making it easy to model using a 3D printer.
In addition, some or all of the bone parts 2B among the bone parts 2B constituting the skeleton 2 may extend while being curved. In this case, by having some or all of the bone parts 2B bent, it is possible to prevent a sudden change in shape of the bone parts 2B and therefore the porous structure 1 when a load is input, and to suppress local buckling.

In this example, each bone 2B constituting the skeletal part 2 has approximately the same shape and length. However, this is not limited to this example, and the shape and/or length of each bone 2B constituting the skeletal part 2 do not have to be the same, and for example, the shape and/or length of some bones 2B may be different from the other bones 2B. In this case, by making the shape and/or length of a specific part of the bones 2B of the skeletal part 2 different from the other parts, it is possible to intentionally obtain different mechanical properties.

In this example, the width W0 (FIG. 14) and cross-sectional area of each bone portion 2B are constant over the entire length of the bone portion 2B (i.e., uniform along the extension direction of the bone portion 2B).
Here, the cross-sectional area of the bone portion 2B refers to the cross-sectional area of a cross section of the bone portion 2B perpendicular to the skeletal line O. Moreover, the width W0 (FIG. 14) of the bone portion 2B refers to the maximum width in the cross section when measured along the cross section perpendicular to the skeletal line O of the bone portion 2B.
However, in each example described in this specification, the width W0 and/or cross-sectional area of some or all of the bone parts 2B constituting the skeletal part 2 may be non-uniform along the extension direction of the bone part 2B. For example, the width W0 of some or all of the bone parts 2B constituting the skeletal part 2 may be gradually increased or decreased toward both ends in the extension direction of the bone part 2B in a portion including the end parts 2Be on both sides in the extension direction of the bone part 2B. Also, the cross-sectional area of some or all of the bone parts 2B constituting the skeletal part 2 may be gradually increased or decreased toward both ends in the extension direction of the bone part 2B in a portion including the end parts 2Be on both sides in the extension direction of the bone part 2B.

In each example described in this specification, from the viewpoint of simplifying the structure of the skeleton 2 and thus facilitating the manufacture of the porous structure 1 by a 3D printer, the width W0 (FIG. 14) of the bone portion 2B is preferably 0.05 mm or more, and more preferably 0.10 mm or more. When the width W0 is 0.05 mm or more, it is possible to mold with the resolution of a high-performance 3D printer, and when it is 0.10 mm or more, it is possible to mold with the resolution of not only a high-performance 3D printer but also a general-purpose 3D printer.
On the other hand, from the viewpoint of improving the accuracy of the outer edge (outer contour) shape of the skeleton portion 2, from the viewpoint of reducing the gaps (spacing) between the cell holes C, and from the viewpoint of improving the characteristics as a cushioning material, it is preferable that the width W0 of the bone portion 2B be 2.0 mm or less.
It is preferable that each of the bone parts 2B constituting the skeletal part 2 satisfy this configuration, but it is also acceptable for only some of the bone parts 2B constituting the skeletal part 2 to satisfy this configuration, and even in this case, a similar effect can be obtained, although to varying degrees.

In this example, each of the bones 2B constituting the skeleton 2 is columnar, and each has a circular (perfect circular) cross-sectional shape.
This simplifies the structure of the skeleton 2, making it easier to model using a 3D printer. In addition, it is easy to reproduce the mechanical properties of general polyurethane foam manufactured through a process of foaming by chemical reaction. This improves the properties of the porous structure 1 as a cushioning material. Furthermore, by forming the bones 2B in a columnar shape in this way, the durability of the skeleton 2 can be improved compared to the case where the bones 2B are replaced with thin membrane-like parts.
The cross-sectional shape of each bone portion 2B is the shape of a cross section perpendicular to the central axis (skeleton line O) of the bone portion 2B.
In addition, without being limited to this example, only some of the bone parts 2B among the bone parts 2B that constitute the skeletal part 2 may satisfy this configuration, and even in that case, the same effect can be obtained, although to different degrees.
For example, in each example described in this specification, the cross-sectional shape of all or some of the bones 2B constituting the skeleton 2 may be a polygon (equilateral triangle, triangle other than equilateral triangle, rectangle, etc.) or a circle other than a perfect circle (ellipse, etc.), and even in such cases, the same effect as in this example can be obtained. Furthermore, the cross-sectional shape of each bone 2B may be uniform along its extension direction, or may be non-uniform along its extension direction. Furthermore, the cross-sectional shapes of each bone 2B may differ from each other.

In each example described in this specification, it is preferable that the ratio (VB×100/VS [%)) of the volume VB occupied by the skeleton part 2 to the apparent volume VS of the skeleton part 2 is 3 to 10%. With this configuration, the reaction force generated in the skeleton part 2 when an external force is applied to the skeleton part 2, and thus the hardness of the skeleton part 2 (and thus the hardness of the porous structure 1) can be improved as a cushioning material, for example, as a seat pad (particularly a seat pad for a vehicle).
Here, the "apparent volume VS of the skeleton 2" refers to the volume of the entire internal space surrounded by the outer edge (outer contour) of the skeleton 2 (the sum of the volume occupied by the skeleton 2, the volume occupied by the membrane 3 (Figure 17) described below if provided, and the volume occupied by the voids).
When the material constituting the skeleton 2 is considered to be the same, the higher the ratio of the volume VB occupied by the skeleton 2 to the apparent volume VS of the skeleton 2, the harder the skeleton 2 (and thus the porous structure 1) will be. Also, the lower the ratio of the volume VB occupied by the skeleton 2 to the apparent volume VS of the skeleton 2, the softer the skeleton 2 (and thus the porous structure 1) will be.
From the viewpoint of improving the reaction force generated in the skeletal portion 2 when an external force is applied to the skeletal portion 2, and thus the hardness of the skeletal portion 2 (and thus the porous structure 1) as a cushioning material, for example, as a seat pad (particularly a seat pad for a vehicle), it is more preferable that the proportion of the volume VB occupied by the skeletal portion 2 in the apparent volume VS of the skeletal portion 2 be 4 to 8%.
Any method may be used to adjust the proportion of the volume VB occupied by the skeletal portion 2 in the apparent volume VS of the skeletal portion 2, but examples include a method of adjusting the thickness (cross-sectional area) of some or all of the bone portions 2B that constitute the skeletal portion 2 and/or the size (cross-sectional area) of some or all of the joint portions J that constitute the skeletal portion 2.

In each example described in this specification, the 25% hardness of the porous structure 1 is preferably 60 to 500 N, and more preferably 100 to 450 N. Here, the 25% hardness (N) of the porous structure 1 is a measured value obtained by measuring the load (N) required to compress the porous structure by 25% in an environment of 23°C and relative humidity of 50% using an Instron type compression tester. This allows the porous structure 1 to have a good hardness as a cushioning material, for example, as a seat pad (particularly a seat pad for a vehicle).

As shown in FIGS. 14 to 16, in this example, the skeleton 2 has a plurality of cell partitions 21 (the same as the number of cell holes C) that partition the cell holes C therein.
16 shows a single cell partition 21. The skeleton 2 of this example has a structure in which a large number of cell partitions 21 are aligned in each of the X, Y, and Z directions.
14 to 16, each cell partition 21 has a plurality of (14 in this example) annular portions 211. Each annular portion 211 is configured in an annular shape, and defines a flat imaginary plane V1 by the inner peripheral edge portion 2111 of each annular portion. The imaginary plane V1 is a virtual plane (i.e., a virtual closed plane) defined by the inner peripheral edge portion 2111 of the annular portion 211. The multiple annular portions 211 constituting the cell partition 21 are connected to each other such that the imaginary planes V1 defined by the inner peripheral edge portions 2111 do not intersect with each other.
The cell hole C is defined by a plurality of annular portions 211 constituting the cell partitioning portion 21 and a plurality of imaginary surfaces V1 defined by the plurality of annular portions 211. In general terms, the annular portions 211 are portions defining the sides of the three-dimensional shape of the cell hole C, and the imaginary surfaces V1 are portions defining the constituent surfaces of the three-dimensional shape of the cell hole C.
Each annular portion 211 is composed of a plurality of bone portions 2B and a plurality of connecting portions 2J that connect the ends 2Be of the plurality of bone portions 2B to each other.
A connection portion between a pair of mutually connected annular portions 211 is configured with one bone portion 2B and a pair of connecting portions 2J on both sides thereof, which are shared by the pair of annular portions 211. In other words, each bone portion 2B and each connecting portion 2J is shared by a plurality of adjacent annular portions 211.
Each imaginary surface V1 defines a portion of one cell hole C by one surface of the imaginary surface V1 (the front surface of the imaginary surface V1), and defines a portion of another cell hole C by the other surface of the imaginary surface V1 (the back surface of the imaginary surface V1). In other words, each imaginary surface V1 defines a portion of a different cell hole C by both its front and back surfaces. In further other words, each imaginary surface V1 is shared by a pair of cell holes C adjacent to the imaginary surface V1 (i.e., a pair of cell holes C sandwiching the imaginary surface V1 therebetween).
Moreover, each annular portion 211 is shared by a pair of cell partitions 21 adjacent to the annular portion 211 (i.e., a pair of cell partitions 21 sandwiching the annular portion 211 therebetween). In other words, each annular portion 211 constitutes a part of each of the pair of cell partitions 21 adjacent to each other.
14 and 15, a part of imaginary surfaces V1 in the porous structure 1 is not covered by a membrane 3 (FIG. 17) described later and is open, i.e., forms an opening. Therefore, the cell holes C communicate with each other through the imaginary surfaces V1, and ventilation between the cell holes C is possible. This improves the ventilation of the skeleton 2 and facilitates compression and restoration deformation of the skeleton 2 in response to application and release of an external force.

As shown in FIG. 16, in this example, the skeleton line O of each cell partition 21 has a polyhedral shape, and therefore each cell hole C has a substantially polyhedral shape. More specifically, in the examples of FIG. 14 to FIG. 16, the skeleton line O of each cell partition 21 has a Kelvin tetradecahedron (truncated octahedron) shape, and therefore each cell hole C has a substantially Kelvin tetradecahedron (truncated octahedron) shape. The Kelvin tetradecahedron (truncated octahedron) is a polyhedron composed of six regular quadrilateral constituent faces and eight regular hexagonal constituent faces. The cell holes C constituting the skeleton 2 are arranged with regularity so as to fill the internal space surrounded by the outer edge (outer contour) of the skeleton 2 (i.e., so that the cell holes C are arranged without any unnecessary gaps, in other words, so as to reduce the gaps (spacing) between the cell holes C).
As in this example, by making the shape of the skeletal lines O of the cell partition sections 21 of some or all (in this example, all) of the skeletal section 2 (and thus the shape of the cell holes C of some or all (in this example, all) of the skeletal section 2) a polyhedron, it is possible to make the gaps (spacing) between the cell holes C that constitute the skeletal section 2 smaller, and more cell holes C can be formed inside the skeletal section 2. This also makes it possible for the skeletal section 2 (and thus the porous structure 1) to exhibit better compression and restoration deformation behavior in response to the application and release of external forces when used as a cushioning material, for example as a seat pad (particularly a seat pad for a vehicle).
The polyhedral shape of the skeleton lines O of the cell partitions 21 (and thus the polyhedral shape of the cell holes C) is not limited to this example, and may be any shape. For example, the shape of the skeleton lines O of the cell partitions 21 (and thus the shape of the cell holes C) is preferably an approximately tetrahedron, an approximately octahedron, or an approximately dodecahedron from the viewpoint of reducing the gaps (spacing) between the cell holes C. The shape of the skeleton lines O of some or all of the cell partitions 21 of the skeleton 2 (and thus the shape of some or all of the cell holes C of the skeleton 2) may be a three-dimensional shape other than an approximately polyhedron (for example, a sphere, an ellipsoid, a cylinder, etc.). The skeleton 2 may have only one type of cell partitions 21 having the same shape of the skeleton lines O as the cell partitions 21, or may have multiple types of cell partitions 21 having different shapes of the skeleton lines O. Similarly, the skeleton 2 may have only one type of cell holes C having the same shape as the cell holes C, or may have a plurality of types of cell holes C having different shapes. When the shape of the skeleton lines O of the cell partitioning parts 21 (and thus the shape of the cell holes C) is made to be a substantial Kelvin tetradecahedron (truncated octahedron) as in this example, it is easiest to reproduce the characteristics of a cushioning material equivalent to that of a general polyurethane foam manufactured through a process of foaming by chemical reaction, compared to other shapes.

14 to 16, in this example, the multiple (14 in this example) annular portions 211 constituting the cell partition 21 each include one or more (six in this example) small annular portions 211S and one or more (eight in this example) large annular portions 211L. Each small annular portion 211S defines a flat small imaginary surface V1S by its annular inner peripheral edge 2111. Each large annular portion 211L defines a large imaginary surface V1L that is flat and has a larger area than the small imaginary surface V1S by its annular inner peripheral edge 2111. The small imaginary surface V1S and the large imaginary surface V1L are each an imaginary plane (i.e., an imaginary closed plane).
16, in this example, the large annular portion 211L has a skeleton line O that forms a regular hexagon, and accordingly, the large imaginary surface V1L also has a substantially regular hexagon. Also, in this example, the small annular portion 211S has a skeleton line O that forms a regular rectangle, and therefore, the small imaginary surface V1S also has a substantially regular rectangle. Thus, in this example, the small imaginary surface V1S and the large imaginary surface V1L differ not only in area but also in shape.
Each of the large annular portions 211L is composed of a plurality of (six in this example) bone portions 2B and a plurality of (six in this example) connecting portions 2J connecting the ends 2Be of the bone portions 2B. Each of the small annular portions 211S is composed of a plurality of (four in this example) bone portions 2B and a plurality of (four in this example) connecting portions 2J connecting the ends 2Be of the bone portions 2B.
14 to 16, the skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 each form a Kelvin tetradecahedron (truncated octahedron). As described above, a Kelvin tetradecahedron (truncated octahedron) is a polyhedron composed of six regular quadrilateral constituent faces and eight regular hexagonal constituent faces. Accordingly, the cell holes C defined by each cell partition 21 also form approximately a Kelvin tetradecahedron. The skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 are connected to each other so as to fill the space. In other words, there are no gaps between the skeleton lines O of the multiple cell partitions 21.

In this way, in this example, the skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 each form a polyhedron (in this example, a Kelvin tetrahedron), and accordingly, the cell holes C form an approximately polyhedron (in this example, an approximately Kelvin tetrahedron), so that it is possible to make the gaps (spacings) between the cell holes C constituting the porous structure 1 smaller, and more cell holes C can be formed inside the porous structure 1. This also makes it possible for the porous structure 1 to be better in terms of the behavior of compression and restoration deformation in response to the application and release of an external force as a cushioning material, for example, as a seat pad (particularly a seat pad for a vehicle). The gaps (spacings) between the cell holes C correspond to the fleshy parts (bone parts 2B and joint parts 2J) of the skeleton 2 that partition the cell holes C.
In addition, in this example, the skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 are connected to each other so as to fill the space, so that it is possible to further reduce the gaps (intervals) between the cell holes C constituting the porous structure 1. This improves the characteristics of the porous structure as a cushioning material.

The polyhedron formed by the skeleton lines O of the cell partitioning portion 21 (and thus the approximate polyhedron formed by the cell holes C) is not limited to the examples shown in the figures, and any desired shape is possible.
For example, it is preferable that the polyhedron formed by the skeleton lines O of the multiple cell partitions 21 constituting the skeleton part 2 (and thus the approximate polyhedron formed by the cell holes C) is one that can fill the space (can be arranged without gaps). This allows the skeleton lines O of the multiple cell partitions 21 constituting the skeleton part 2 to be connected to each other so as to fill the space, thereby improving the characteristics of the porous structure as a cushioning material. In this case, the polyhedron formed by the skeleton lines O of the multiple cell partitions 21 constituting the skeleton part 2 (and thus the approximate polyhedron formed by the cell holes C) may include only one type of polyhedron as in this example, or may include multiple types of polyhedrons. Here, with respect to the polyhedron, the "type" refers to the shape (the number of constituent faces and the shape), and specifically, two polyhedrons that have different shapes (the number of constituent faces and the shape) are treated as two types of polyhedrons, but two polyhedrons that have the same shape and only different dimensions are treated as the same type of polyhedron. Examples of polyhedrons formed by the skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 that can fill space and include only one type of polyhedron include a regular triangular prism, a regular hexagonal prism, a cube, a rectangular parallelepiped, and a rhombic dodecahedron, in addition to a Kelvin tetradecahedron. As shown in the examples of the figures, when the shape of the skeleton lines O of the cell partitions 21 is a Kelvin tetradecahedron (truncated octahedron), it is easier to reproduce the characteristics of a cushioning material equivalent to that of a general polyurethane foam manufactured through a process of foaming by chemical reaction, compared to other shapes. Also, when the shape of the skeleton lines O of the cell partitions 21 is a Kelvin tetradecahedron (truncated octahedron), it is possible to obtain mechanical properties equal to those in the XYZ directions. When the polyhedron formed by the skeleton lines O of the multiple cell partitions 21 constituting the skeleton 2 can fill space and includes multiple types of polyhedrons, examples of the polyhedrons include a combination of a regular tetrahedron and a regular octahedron, a combination of a regular tetrahedron and a truncated tetrahedron, a combination of a regular octahedron and a truncated hexahedron, etc. Note that these are examples of combinations of two types of polyhedrons, but combinations of three or more types of polyhedrons are also possible.
Furthermore, the polyhedron formed by the skeleton lines O of the multiple cell partition sections 21 that make up the skeleton section 2 (and thus the approximate polyhedron formed by the cell holes C) can be, for example, any regular polyhedron (a convex polyhedron in which all faces are congruent regular polygons and the number of faces that meet at all vertices is equal), a semi-regular polyhedron (a convex polyhedron in which all faces are regular polygons and all vertices have congruent shapes (the types and order of regular polygons that meet at the vertices are the same) other than a regular polyhedron), a prism, a pyramid, etc.
Furthermore, the skeleton lines O of some or all of the cell partitions 21 constituting the skeleton 2 may have a three-dimensional shape other than a polyhedron (e.g., a sphere, an ellipsoid, a cylinder, etc.). Furthermore, some or all of the cell holes C constituting the skeleton 2 may have an approximately three-dimensional shape other than an approximately polyhedron (e.g., an approximately sphere, an approximately ellipsoid, an approximately cylinder, etc.).

The multiple annular portions 211 constituting the cell partition portion 21 include small annular portions 211S and large annular portions 211L of different sizes, which makes it possible to further reduce the gaps (spacing) between the cell holes C constituting the skeletal portion 2. Furthermore, when the small annular portions 211S and the large annular portions 211L have different shapes as in this example, it becomes possible to further reduce the gaps (spacing) between the cell holes C constituting the skeletal portion 2.
However, the multiple annular portions 211 constituting the cell partition 21 may each have the same size and/or shape. When the annular portions 211 constituting the cell partition 21 have the same size and shape, it is possible to obtain equal mechanical properties in each of the X, Y, and Z directions.

As in this example, the skeleton lines O of some or all (in this example, all) of the annular portions 211 constituting the cell partitioning portion 21 (and thus some or all (in this example, all) of the virtual surfaces V1 constituting the cell partitioning portion 21) are substantially polygonal, which makes it possible to reduce the intervals between the cell holes C constituting the skeleton portion 2. In addition, the behavior of the compression and restoration deformation of the skeleton portion 2 in response to the application and release of an external force becomes better as a seat pad, particularly as a seat pad for a vehicle. In addition, since the shape of the annular portion 211 (and thus the shape of the virtual surface V1) is simplified, the manufacturability and ease of adjustment of the characteristics can be improved. Note that, when at least one annular portion 211 (and thus at least one virtual surface V1 of the virtual surfaces V1 constituting the skeleton portion 2) of the annular portions 211 constituting the skeleton portion 2 satisfies this configuration, a similar effect can be obtained, although there may be differences in degree.
In addition, the skeleton line O of at least one of the annular portions 211 constituting the skeleton portion 2 (and thus at least one of the virtual surfaces V1 constituting the skeleton portion 2) may be any substantially polygonal shape other than the substantially regular hexagon or substantially regular quadrangle as in this example, or a planar shape other than a substantially polygonal shape (for example, a circle (a perfect circle, an ellipse, etc.)). When the shape of the skeleton line O of the annular portion 211 (and thus the shape of the virtual surface V1) is a circle (a perfect circle, an ellipse, etc.), the shape of the annular portion 211 (and thus the shape of the virtual surface V1) becomes simple, which improves manufacturability and ease of adjusting the characteristics, and provides more uniform mechanical characteristics. For example, when the shape of the skeletal line O of the annular portion 211 (and thus the shape of the virtual surface V1) is an ellipse (horizontal ellipse) that is elongated in a direction approximately perpendicular to the direction in which the load is applied, the annular portion 211, and thus the skeletal portion 2 (and thus the porous structure 1) are more easily deformed (softer) in response to the input of load than when the shape is an ellipse (vertical ellipse) that is elongated in a direction approximately parallel to the direction in which the load is applied.

In this example, it is preferable that the skeleton 2 has at least one cell hole C having a diameter of 5 mm or more. This makes it easier to manufacture the porous structure 1 using a 3D printer. If the diameter of each cell hole C of the skeleton 2 is less than 5 mm, the structure of the skeleton 2 becomes too complicated, and it may be difficult to generate three-dimensional shape data (CAD data, etc.) representing the three-dimensional shape of the porous structure 1, or 3D printing data generated based on the three-dimensional shape data, on a computer.
Incidentally, since conventional porous structures are manufactured through a process of foaming by chemical reaction, it is not easy to form cell holes C having a diameter of 5 mm or more.
Furthermore, by having the skeletal portion 2 have cell holes C with a diameter of 5 mm or more, the breathability and ease of deformation of the skeletal portion 2 can be easily improved.
From this viewpoint, it is preferable that the diameter of each of the cell holes C constituting the skeleton portion 2 is 5 mm or more.
The larger the diameter of the cell hole C, the easier it is to manufacture the porous structure 1 using a 3D printer, and the easier it is to improve the breathability and ease of deformation. From this viewpoint, it is preferable that the diameter of at least one (preferably all) of the cell holes C in the skeleton 2 is 8 mm or more, and even more preferably 10 mm or more.
On the other hand, if the cell holes C of the skeleton 2 are too large, it becomes difficult to form the outer edge (outer contour) shape of the skeleton 2 (and thus the porous structure 1) neatly (smoothly), and the shape precision of the porous structure 1 may decrease, resulting in a poor appearance. In addition, the characteristics as a cushioning material (e.g., a seat pad, particularly a seat pad for a vehicle) may not be sufficiently good. Therefore, from the viewpoint of improving the appearance and the characteristics as a cushioning material (e.g., a seat pad, particularly a seat pad for a vehicle), the diameter of each cell hole C of the skeleton 2 is preferably less than 30 mm, more preferably 25 mm or less, and even more preferably 20 mm or less.
The more cell holes C that the porous structure 1 has and that satisfy the above-mentioned numerical ranges for diameter, the more likely it is that the above-mentioned effects can be obtained. From this viewpoint, it is preferable that the diameter of each of the cell holes C that constitute the porous structure 1 satisfies at least one of the above-mentioned numerical ranges. Similarly, it is more preferable that the average value of the diameters of the cell holes C that constitute the porous structure 1 satisfies at least one of the above-mentioned numerical ranges.
In addition, the diameter of the cell hole C refers to the diameter of the circumscribed sphere of the cell hole C when the cell hole C has a shape other than a strictly spherical shape as in this example.

If the cell holes C of the skeleton 2 are too small, the structure of the skeleton 2 becomes too complicated, and as a result, it may be difficult to generate three-dimensional shape data (CAD data, etc.) representing the three-dimensional shape of the porous structure 1, or 3D modeling data generated based on the three-dimensional shape data, on a computer, making it difficult to manufacture the porous structure 1 using a 3D printer. From the viewpoint of facilitating the manufacture of the porous structure 1 using a 3D printer, it is preferable that the diameter of the cell hole C having the smallest diameter among the cell holes C constituting the skeleton 2 is 0.05 mm or more, and more preferably 0.10 mm or more. When the diameter of the cell hole C having the smallest diameter is 0.05 mm or more, it can be modeled with the resolution of a high-performance 3D printer, and when it is 0.10 mm or more, it can be modeled with the resolution of not only a high-performance 3D printer but also a general-purpose 3D printer.

Fig. 17 is a drawing for explaining a modified example of the cell partition 21 of the porous structure 1, and corresponds to Fig. 16. In each example described in this specification, the porous structure 1 may include one or more membranes 3 in addition to the skeleton 2, as in the modified example shown in Fig. 17.
The membrane 3 extends on an imaginary plane V1 defined by the annular inner peripheral edge 2111 of the annular portion 211, thereby covering the imaginary plane V1 defined by the annular portion 211. In the porous structure 1 of the example of FIG. 17, at least one of the imaginary planes V1 constituting the skeleton portion 2 is covered with the membrane 3. The membrane 3 is made of the same material as the skeleton portion 2 and is integrally formed with the skeleton portion 2. In the example of FIG. 17, the membrane 3 is configured to be flat. However, the membrane 3 may be configured to be non-flat (for example, curved (curved)).
The membrane 3 preferably has a thickness smaller than the width W0 (FIG. 14) of the bone portion 2B.
The membrane 3 prevents the two cell holes C sandwiching the virtual surface V1 from communicating with each other through the virtual surface V1, and ventilation through the virtual surface V1 is not possible, which leads to a decrease in the overall air permeability of the porous structure 1. By adjusting the number of the virtual surfaces V1 that constitute the porous structure 1 that are covered with the membrane 3, the overall air permeability of the porous structure 1 can be adjusted, and various air permeability levels can be achieved according to requirements. From the viewpoint of promoting the compression/restoration deformation of the porous structure 1 and the interaction between the porous structure 1 and the viscous fluid F, it is not preferable that all of the virtual surfaces V1 that constitute the porous structure 1 are covered with the membrane 3. In other words, it is preferable that at least one of the virtual surfaces V1 that constitute the porous structure 1 is not covered with the membrane 3 and is open, and it is more preferable that all of the virtual surfaces V1 that constitute the porous structure 1 are not covered with the membrane 3 and are open.
As described above, conventional porous structures are manufactured through a process of foaming by chemical reaction, and therefore it is difficult to form the membranes in the communication holes that communicate with each cell at the desired positions and in the desired number. When the porous structure 1 is manufactured by a 3D printer as in this example, the information on the membrane 3 is included in the 3D printing data read into the 3D printer in advance, so that the membranes 3 can be reliably formed at the desired positions and in the desired number.
At least one of the small imaginary surfaces V1S constituting the skeleton 2 may be covered with the film 3. And/or at least one of the large imaginary surfaces V1L constituting the skeleton 2 may be covered with the film 3.

Next, with reference to Figures 18 to 19, other examples of the porous structure 1 that can be provided in the porous structure 1 according to any embodiment of the present invention will be described, focusing on the points that differ from the examples in Figures 14 to 16.
18 to 19, only the configuration of the bone portion 2B of the skeleton portion 2 of the porous structure 1 is different from the examples of FIGS. 14 to 16. In the example of FIGS.
The porous structure 1 may or may not comprise the membrane 3 (FIG. 17) described above.
18, the skeleton lines O of the cell partitions 21 constituting the skeleton 2 each form a Kelvin tetradecahedron, and accordingly, the cell holes C each form an approximately Kelvin tetradecahedron. However, as described in the explanation of the examples of Figures 14 to 16, also in the example of Figure 18, the skeleton lines O of the cell partitions 21 constituting the skeleton 2 each may have any shape, and accordingly, the cell holes C may also have any shape.

Fig. 18 is a plan view showing another example of the porous structure 1 that can be provided in the porous structure 1 according to any embodiment of the present invention, and corresponds to Fig. 15. Fig. 19 shows the bone portion 2B of this example alone. Fig. 19(a) shows the natural state of the bone portion 2B in which no external force is applied, and Fig. 19(b) shows the state in which an external force is applied to the bone portion 2B. Figs. 18 and 19 show the central axis (skeleton line O) of the bone portion 2B.
As shown in FIG. 18 and FIG. 19(a), each bone portion 2B of the skeleton 2 is composed of a bone constant portion 2B1 that extends while maintaining a constant cross-sectional area, and a pair of bone change portions 2B2 that extend from the bone constant portion 2B1 to the connecting portion 2J while gradually changing the cross-sectional area on both sides of the extension direction of the bone constant portion 2B1. In this example, each bone change portion 2B2 extends from the bone constant portion 2B1 to the connecting portion 2J while gradually increasing the cross-sectional area. Note that, not limited to this example, the same effect can be obtained even if only some of the bone portions 2B constituting the skeleton 2 satisfy this configuration. In addition, some or all of the bone portions 2B constituting the skeleton 2 may have the bone change portion 2B2 only at one end of the bone constant portion 2B1, and the other end of the bone constant portion 2B1 may be directly connected to the connecting portion 2J, and in this case, the same effect can be obtained, although there may be differences in degree.
Here, the cross-sectional areas of the bone constant portion 2B1 and the bone changed portion 2B2 refer to the cross-sectional areas of cross sections perpendicular to the skeleton line O of the bone constant portion 2B1 and the bone changed portion 2B2, respectively.
In this example, each bone portion 2B constituting the porous structure 1 is composed of a bone constant portion 2B1 and a bone change portion 2B2, and the cross-sectional area of the bone change portion 2B2 gradually increases from the bone constant portion 2B1 toward the joint portion 2J, so that the bone portion 2B has a constricted shape that narrows toward the bone constant portion 2B1 in the vicinity of the boundary between the bone constant portion 2B1 and the bone change portion 2B2. Therefore, when an external force is applied, the bone portion 2B is easily buckled and deformed at the constricted portion and the middle portion of the bone constant portion 2B1, and the porous structure 1 is easily compressed and deformed. This provides behavior and characteristics equivalent to those of a general polyurethane foam manufactured through a process of foaming by chemical reaction. This also makes the surface of the porous structure 1 softer to the touch. Therefore, for example, when sitting, especially at the beginning of sitting, a softer feeling is given to the seated person. Such a soft feel is generally widely preferred, and is also preferred by occupants of luxury car seat pads (e.g., occupants sitting in the back seat when a chauffeur is driving the car and passengers are seated in the back seat).

When the bone portion 2B has a bone fixed portion 2B1 at least in a portion thereof as in this example, the ratio A0/A1 of the cross-sectional area A0 ( FIG. 19( a )) of the bone fixed portion 2B1 to the cross-sectional area A1 ( FIG. 19( a )) of the end 2B21 on either side (preferably both sides) of the bone portion 2B is
0.15≦A0/A1≦2.0
It is preferable that the ratio A0/A1 is satisfied. As a result, the touch of the surface of the porous structure 1 can be made not too soft or too hard, but moderately hard, as a characteristic of the seat pad (particularly a vehicle seat pad). Therefore, for example, when sitting, especially at the beginning of sitting, the seated person is given a feeling of moderate hardness. The smaller the ratio A0/A1, the softer the touch of the surface of the porous structure 1. If the ratio A0/A1 is less than 0.15, the touch of the surface of the porous structure 1 may be too soft, which may be undesirable as a characteristic of the seat pad (particularly a vehicle seat pad), and it is difficult to manufacture using a 3D printer, which is undesirable in terms of manufacturability. If the ratio A0/A1 is more than 2.0, the touch of the surface of the porous structure 1 may be too hard, which may be undesirable as a characteristic of the seat pad (particularly a vehicle seat pad).
It is more preferable that the ratio A0/A1 is 0.5 or more.
More specifically, in the example of Figures 18 to 19, the bone portion 2B has a bone constant portion 2B1 and a pair of bone change portions 2B2 continuous with both sides of the bone constant portion 2B1, and each bone change portion 2B2 extends from the bone constant portion 2B1 to the joint portion 2J while gradually increasing the cross-sectional area, and the ratio A0/A1 is less than 1.0. This allows the touch feeling of the surface of the porous structure 1 to be relatively soft as a characteristic of a seat pad (particularly a vehicle seat pad). Such a soft touch is generally widely preferred, and is also preferred by passengers in the seat pad of a luxury car (for example, passengers sitting in the back seat when a chauffeur is driving a car and passengers are sitting in the back seat).
In addition, each bone part 2B constituting the skeletal part 2 may satisfy this configuration, or only some of the bone parts 2B among the bone parts 2B constituting the skeletal part 2 may satisfy this configuration, and in either case, the same effect can be obtained, although to different degrees.

Instead of the example of FIG. 18-FIG. 19, the bone change portion 2B2 may extend from the bone constant portion 2B1 to the connecting portion 2J while gradually decreasing the cross-sectional area. In this case, the bone constant portion 2B1 has a larger (thicker) cross-sectional area than the bone change portion 2B2. As a result, when an external force is applied, the bone constant portion 2B1 is less likely to deform, and instead, the bone change portion 2B2 (particularly the portion on the connecting portion 2J side) is relatively prone to buckling, and the porous structure 1 is less likely to be compressed and deformed. As a result, the touch of the surface of the porous structure 1 becomes harder, and mechanical properties of high hardness are obtained. Therefore, for example, when sitting, especially at the beginning of sitting, the seated person is given a harder feel. Such behavior is not easy to obtain with general polyurethane foam manufactured through a process of foaming by chemical reaction. This configuration can accommodate users who prefer a harder feel. Such a firm feel is preferred by occupants in seat pads of sports cars, for example, which are used during rapid acceleration, deceleration, and lane changes.
When the bone transformation portion 2B2 extends from the bone constant portion 2B1 to the joint portion 2J while gradually decreasing its cross-sectional area, the ratio A0/A1 exceeds 1.0.
In addition, each bone part 2B constituting the skeletal part 2 may satisfy this configuration, or only some of the bone parts 2B among the bone parts 2B constituting the skeletal part 2 may satisfy this configuration, and in either case, the same effect can be obtained, although to different degrees.

In the examples of Figures 14 to 16 described above in the first embodiment, the bone portion 2B does not have a bone-changing portion 2B2, and is composed of only a bone-fixed portion 2B1. In this case, the cross-sectional area of the bone portion 2B is constant over its entire length. The touch feeling of the surface of the porous structure 1 when an external force is applied is medium hardness. This configuration can accommodate users who prefer a medium hardness feel. In addition, it can be suitably applied to seat pads of all types of vehicles, such as luxury cars and sports cars.
In this case, the ratio A0/A1 is 1.0.
In addition, each bone part 2B constituting the skeletal part 2 may satisfy this configuration, or only some of the bone parts 2B among the bone parts 2B constituting the skeletal part 2 may satisfy this configuration, and in either case, the same effect can be obtained, although to different degrees.

Returning to the example of Figures 18-19, in this example, in each bone portion 2B constituting the skeletal portion 2, the bone constant portion 2B1 has a smaller cross-sectional area than the bone changed portion 2B2 and the connecting portion 2J. More specifically, the cross-sectional area of the bone constant portion 2B1 is smaller than the cross-sectional area of any portion of the bone changed portion 2B2 and the connecting portion 2J (excluding the boundary portion between the bone constant portion 2B1 and the bone changed portion 2B2). In other words, the bone constant portion 2B1 is the portion of the skeletal portion 2 with the smallest cross-sectional area (thinnest). As a result, as in the above, when an external force is applied, the bone constant portion 2B1 is more likely to deform, and thus the porous structure 1 is more likely to be compressed and deformed. This makes the surface of the porous structure 1 feel softer to the touch.
The cross-sectional area of the joint 2J refers to the cross-sectional area of a cross section perpendicular to the skeleton line O of the joint 2J.
In addition, without being limited to this example, only some of the bone parts 2B among the bone parts 2B that constitute the skeletal part 2 may satisfy this configuration, and even in that case, the same effect can be obtained, although to different degrees.

18-19, in each bone portion 2B constituting the skeletal portion 2, the bone constant portion 2B1 has a smaller width than the bone changed portion 2B2 and the connecting portion 2J. More specifically, the width of the bone constant portion 2B1 is smaller than the width of any portion of the bone changed portion 2B2 and the connecting portion 2J (excluding the boundary portion between the bone constant portion 2B1 and the bone changed portion 2B2). In other words, the bone constant portion 2B1 is the portion of the skeletal portion 2 with the smallest width (thinnest). This also makes the bone constant portion 2B1 more easily deformable when an external force is applied, which makes the surface of the porous structure 1 feel softer to the touch.
The widths of bone constant portion 2B1, bone changed portion 2B2, and connecting portion 2J refer to the maximum widths when measured along a cross section perpendicular to the skeleton line O of bone constant portion 2B1, bone changed portion 2B2, and connecting portion 2J. The skeleton line O of connecting portion 2J is the portion of the skeleton line O that corresponds to connecting portion 2J. For reference, width W0 of bone constant portion 2B1 and width W1 of bone changed portion 2B2 are shown in Figure 19(a).
In addition, without being limited to this example, only some of the bone parts 2B among the bone parts 2B that constitute the skeletal part 2 may satisfy this configuration, and even in that case, the same effect can be obtained, although to different degrees.

In each of the above-mentioned examples, from the viewpoint of simplifying the structure of the porous structure 1 and, in turn, ease of manufacturing with a 3D printer, the width W0 (FIG. 19) of the bone constant portion 2B1 is preferably 0.05 mm or more, and more preferably 0.10 mm or more. When the width W0 is 0.05 mm or more, modeling is possible with the resolution of a high-performance 3D printer, and when it is 0.10 mm or more, modeling is possible with the resolution of not only a high-performance 3D printer but also a general-purpose 3D printer.
On the other hand, from the viewpoint of improving the accuracy of the outer edge (outer contour) shape of the porous structure 1, from the viewpoint of reducing the gaps (spacing) between the cell holes C, and from the viewpoint of improving the characteristics as a cushioning material, it is preferable that the width W0 (Figure 19) of the bone fixed portion 2B1 be 0.05 mm or more and 2.0 mm or less.
It is preferable that each of the bone parts 2B constituting the skeletal part 2 satisfy this configuration, but it is also acceptable for only some of the bone parts 2B constituting the skeletal part 2 to satisfy this configuration, and even in this case, a similar effect can be obtained, although to varying degrees.

As shown in Figure 19, in this example, each bone portion 2B constituting the skeletal portion 2 has a bone change portion 2B2 having one or more (in this example, three) inclined surfaces 2B23 on its side, and these inclined surfaces 2B23 are inclined (inclined at less than 90°) with respect to the extension direction of the bone change portion 2B2, and the width W2 gradually increases from the bone constant portion 2B1 toward the connection portion 2J.
This also makes it easier for the bone portion 2B to buckle and deform at the constricted portion near the boundary between the bone constant portion 2B1 and the bone transformed portion 2B2 when an external force is applied, and thus makes it easier for the porous structure 1 to undergo compressive deformation. This makes the surface of the porous structure 1 softer to the touch.
Here, the extension direction of the bone changed portion 2B2 is the extension direction of the central axis (skeletal line O) of the bone changed portion 2B2. Moreover, the width W2 of the inclined surface 2B23 of the bone changed portion 2B2 refers to the width of the inclined surface 2B23 when measured along a cross section perpendicular to the skeletal line O of the bone changed portion 2B2.
In addition, without being limited to this example, only some of the bone parts 2B among the bone parts 2B that constitute the skeletal part 2 may satisfy this configuration, and even in that case, the same effect can be obtained, although to different degrees.

In the example of Figures 18 and 19, each bone portion 2B constituting the skeleton 2 is columnar, and the bone constant portion 2B1 and the bone changed portion 2B2 each have a cross-sectional shape of an equilateral triangle.
This simplifies the structure of the porous structure 1, making it easier to model it using a 3D printer. In addition, it is easy to reproduce the mechanical properties of general polyurethane foam manufactured through a process of foaming by chemical reaction. This improves the properties of the porous structure 1 as a cushioning material. Furthermore, by forming the bone portion 2B in a columnar shape in this way, the durability of the porous structure 1 can be improved compared to the case where the bone portion 2B is replaced with a thin membrane-like portion.
The cross-sectional shapes of the bone constant portion 2B1 and the bone changed portion 2B2 are the shapes in a cross section perpendicular to the central axis (skeleton line O) of the bone constant portion 2B1 and the bone changed portion 2B2, respectively.
In addition, without being limited to this example, only some of the bone parts 2B among the bone parts 2B that constitute the skeletal part 2 may satisfy this configuration, and even in that case, the same effect can be obtained, although to different degrees.
In addition, in all or some of the bone parts 2B constituting the skeletal part 2, the cross-sectional shapes of the bone constant part 2B1 and the bone changed part 2B2 may be polygonal other than an equilateral triangle (triangle other than an equilateral triangle, quadrangle, etc.) or may be circular (perfect circle, ellipse, etc.), and the same effect as in this example can be obtained in this case. The cross-sectional shapes of the bone constant part 2B1 and the bone changed part 2B2 may be different from each other. The cross-sectional shapes of each bone part 2B may be uniform along its extension direction, or may be non-uniform along its extension direction. The cross-sectional shapes of each bone part 2B may be different from each other.

The porous structure and the method for manufacturing the porous structure of the present invention can be used for cushioning materials for any purpose, but are particularly suitable for use in seat pads for any vehicle, and are particularly suitable for use in seat pads for vehicles.

1: Porous structure,
2: Skeleton, 2B: Bone, 2Be: End of bone, 2B1: Bone constant part, 2B2: Bone change part, 2B21: End of bone change part on the joining part side, 2B22: End of bone change part on the bone constant part side, 2B23: Sloping surface of bone change part, 2J: Joint part, 21: Cell partition part, 211: Annular part, 211L: Large annular part, 211S: Small annular part, 2111: Inner peripheral edge part of annular part,
3: membrane,
6: hollow portion, 61: first hollow portion, 62: second hollow portion, A1: first region, A2: second region, A1C: center of first region, A2C: center of second region, E1: outer edge of multiple first hollow portions, E2: outer edge of multiple second hollow portions, G1: portion overlapping with first region on projection plane, G2: portion overlapping with second region on projection plane,
C: cell hole, O: skeleton line, V1: virtual surface, V1L: large virtual surface, V1S: small virtual surface, ID: predetermined load input direction, P: projection surface of the predetermined load input direction,
300: Vehicle seat,
302: Cushioning material (seat pad); 302C: Center in the left-right direction;
303: The part directly below the ischium,
310: Cushion pad, 311: Main pad portion (seating portion), 312: Side pad portion, 313: Back pad opposing portion,
320: back pad, 321: main pad section, 322: side pad section,
330: epidermis,
340: Headrest,
350: Recessed portion; 351: Main body portion;
FS: surface on the seat occupant's side (front surface), SS: side surface, BS: back surface, TD: thickness direction, LD: extension direction,
400: 3D printer, 410: control unit, 420: modeling unit, 421: laser irradiator, 430: support stand, 440: container, LL: ultraviolet laser light, LR: liquid resin, 500: 3D modeling data

Claims (10)

A porous structure made of flexible resin or rubber,
The porous structure has a skeleton over almost the entirety thereof,
The skeleton portion is
A plurality of bones;
a plurality of connecting portions each connecting an end portion of the plurality of bone portions to each other;
Equipped with
The porous structure is used for a cushioning material,
the porous structure has a plurality of cavities each of which is not open to an outer surface of the porous structure and is different from cell pores of the porous structure;
the plurality of cavities include a plurality of first cavities,
the first hollow portions are arranged such that a first hollow portion closer to a center of a first region surrounded by outer edges of the first hollow portions on a projection plane of the cushioning material in a predetermined load input direction has a larger volume ;
A porous structure, wherein a portion of the porous structure that overlaps with the first region on the projection plane is configured such that the cross-sectional area of the bone portion is smaller the closer the bone portion is to the center of the first region on the projection plane . A porous structure made of flexible resin or rubber,
The porous structure has a skeleton over almost the entirety thereof,
The skeleton portion is
A plurality of bones;
a plurality of connecting portions each connecting an end portion of the plurality of bone portions to each other;
It is equipped with
The porous structure is used for a cushioning material,
the porous structure has a plurality of cavities each of which is not open to an outer surface of the porous structure and is different from the cell pores of the porous structure;
the plurality of cavities include a plurality of first cavities,
the first hollow portions are arranged such that a first hollow portion closer to a center of a first region surrounded by outer edges of the first hollow portions on a projection plane of the cushioning material in a predetermined load input direction has a larger volume;
the plurality of cavities further includes a plurality of second cavities,
the second hollow portions are arranged such that a second hollow portion closer to a center of a second region surrounded by outer edges of the second hollow portions on the projection plane has a larger volume,
A porous structure, wherein the first region and the second region do not overlap on the projection plane. The porous structure according to claim 1 , wherein, in the projection plane, the first region is disposed so as to overlap with a center of the cushion material in the left-right direction. The porous structure is used as a cushion material for sitting,
The porous structure according to claim 1 or 2, wherein, in the projection plane, the first region is positioned so as to overlap a portion of the cushion material directly below one of the ischial bones of a seated occupant. The porous structure according to claim 2, wherein the portion of the porous structure that overlaps with the second region on the projection plane is configured so that the cross-sectional area of the bone portion that is closer to the center of the second region on the projection plane is smaller. The porous structure is used as a cushion material for sitting,
The porous structure according to claim 2 or 5 , wherein, in the projection plane, the first region and the second region are arranged so as to overlap with a portion of the cushion material directly below a pair of ischial bones of a seated person. The porous structure according to claim 1 , wherein a volume of each of the cavities is greater than a volume of each of the cell holes. The porous structure according to any one of claims 1 to 7 , which is used for a vehicle seat pad. The porous structure according to any one of claims 1 to 8 , wherein the porous structure is formed by a 3D printer. A method for producing a porous structure, comprising the steps of: producing the porous structure according to any one of claims 1 to 8 using a 3D printer.

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