MATTRESS FOR CARE

Abstract

With regard to a care bed provided with a three-dimensional net-like structure made of a thermoplastic resin, an object is to smoothly bend the three-dimensional net-like structure in multiple stages in response to a complicated motion of a bed main body or a user's specific motion. A three-dimensional net-like structure 101 includes a first three-dimensional sparse/dense structure 1 provided as an alternately layered configuration of structural units 1a.sub.1 to 1a.sub.9 that are sparse in an extrusion direction Y and structural units 1b.sub.1 to 1b.sub.8 that are dense in the extrusion direction Y. In this first three-dimensional sparse/dense structure 1, a bulk density .sub.1 of the sparse structural units 1a.sub.1 to 1a.sub.9 is 0.01 to 0.08 g/cm.sup.3 and a bulk density .sub.2 of the dense structural units 1b.sub.1 to 1b.sub.8 is 0.03 to 0.10 g/cm.sup.3. A ratio .sub.2/.sub.1 of the bulk density of the dense structural units 1b.sub.1 to 1b.sub.8 to the bulk density of the sparse structural units 1a.sub.1 to 1a.sub.9 is 1.01 to 5. A length A.sub.1 of the sparse structural units 1a.sub.1 to 1a.sub.9 is 1 to 50 cm, and a length A.sub.2 of the dense structural units 1b.sub.1 to 1b.sub.8 is 3 to 60 cm. A ratio A.sub.2/A.sub.1 of the length of the dense structural units 1b.sub.1 to 1b.sub.8 to the length of the sparse structural units 1a.sub.1 to 1a.sub.9 is 0.1 to 10.

Claims

1. A mattress for care, comprising a three-dimensional net-like structure configured from a first three-dimensional sparse/dense structure, a second three-dimensional sparse/dense structure and a third three-dimensional sparse/dense structure to have a plurality of three-dimensional intersecting regions formed by sparse structural units, wherein the three-dimensional net-like structure has a curled spring structure formed by causing filaments of a thermoplastic resin to be brought into contact with and tangled with one another irregularly at contact points and is configured to have a wire diameter of 0.1 to 2.0 mm , the three-dimensional net-like structure comprises the first three-dimensional sparse/dense structure provided as a layered configuration of a sparse structural unit and a dense structural unit in an extrusion direction, wherein the first three-dimensional sparse/dense structure has a bulk density of 0.01 to 0.08 g/cm.sup.3 for the sparse structural unit, a bulk density of 0.03 to 0.09 g/cm.sup.3 for the dense structural unit, a ratio of the bulk density of the dense structural unit to the bulk density of the sparse structural unit of 1.01 to 5, a length in the extrusion direction of 1 to 50 cm for the sparse structural unit, a length in the extrusion direction of 3 to 60 cm for the dense structural unit, and a ratio of the length of 0.1 to 10, the three-dimensional net-like structure further comprises the second three-dimensional sparse/dense structure provided as a layered configuration of a sparse structural unit and a dense structural unit in a thickness direction, wherein the second three-dimensional sparse/dense structure has a bulk density of 0.01 to 0.08 g/cm.sup.3 for the sparse structural unit, a bulk density of 0.03 to 0.09 g/cm.sup.3 for the dense structural unit, a ratio of the bulk density of the dense structural unit to the bulk density of the sparse structural unit of 1.01 to 5, a thickness of 0.5 to 10 cm for the sparse structural unit, a thickness of 2 to 30 cm for the dense structural unit, and a ratio of the thickness of the dense structural unit to the thickness of the sparse structural unit of 0.2 to 60, and the three-dimensional net-like structure further comprises the third three-dimensional sparse/dense structure provided as a layered configuration of a sparse structural unit and a dense structural unit in a direction perpendicular to the extrusion direction, wherein the third three-dimensional sparse/dense structure has a bulk density of 0.01 to 0.07 g/cm.sup.3 for the sparse structural unit, a bulk density of 0.0128 to 0.09 g/cm.sup.3 for the dense structural unit, a ratio of the bulk density of the dense structural unit to the bulk density of the sparse structural unit of 1.01 to 5, a width of 40 to 100 cm for the sparse structural unit, a width of 4 to 30 cm for the dense structural unit, and a ratio of the width of the dense structural unit to the width of the sparse structural unit of 0.02 to 30, and wherein the sparse structural unit of the third three-dimensional sparse/dense structure comprises a first sparse structural unit and second sparse structural units that are located on both sides of the first sparse structural unit and have a bulk density smaller than a bulk density of the first sparse structural unit, and a width of the second sparse structural units is narrower than a width of the first sparse structural unit.

2. The mattress for care according to claim 1, wherein the second three-dimensional sparse/dense structure has the dense structural unit provided as a surface layer.

3. The mattress for care according to claim 1, wherein the second three-dimensional sparse/dense structure has the dense structural unit provided as an intermediate layer and the sparse structural unit provided as a surface layer.

4. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a perspective view illustrating a three-dimensional net-like structure for a care bed according to a first embodiment of the present disclosure;

[0028] FIG. 2 is a perspective view illustrating the three-dimensional net-like structure (with reference signs for dimensions);

[0029] FIG. 3 is an exploded perspective view illustrating a first three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0030] FIG. 4 is an exploded perspective view illustrating a second three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0031] FIG. 5 is a perspective view illustrating a three-dimensional net-like structure for a care bed according to a second embodiment of the present disclosure;

[0032] FIG. 6 is a front view illustrating a three-dimensional net-like structure according to a modification of the second embodiment for the care bed;

[0033] FIG. 7 is a perspective view illustrating a three-dimensional net-like structure for a care bed according to a third embodiment of the present disclosure;

[0034] FIG. 8 is a perspective view illustrating the three-dimensional net-like structure (with reference signs for dimensions);

[0035] FIG. 9 is an exploded perspective view illustrating a first three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0036] FIG. 10 is an exploded perspective view illustrating a second three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0037] FIG. 11 is an exploded perspective view illustrating a third three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0038] FIG. 12 is a perspective view illustrating a three-dimensional net-like structure for a care bed according to a fourth embodiment of the present disclosure;

[0039] FIG. 13 is a perspective view illustrating the three-dimensional net-like structure (with reference signs for dimensions);

[0040] FIG. 14 is an exploded perspective view illustrating a first three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0041] FIG. 15 is an exploded perspective view illustrating a second three-dimensional sparse/dense structure of the three-dimensional net-like structure;

[0042] FIG. 16 is an exploded perspective view illustrating a third three-dimensional sparse/dense structure of the three-dimensional net-like structure; and

[0043] FIG. 17 is a perspective view illustrating the three-dimensional net-like structure for the care bed according to the fourth embodiment of the present disclosure in a user state.

DESCRIPTION OF EMBODIMENTS

[0044] A three-dimensional net-like structure 101 according to a first embodiment is applied as a core material of a mattress for a care bed. This three-dimensional net-like structure 101 has a curled spring structure formed by causing filaments of a thermoplastic resin to be brought into contact with and tangled with one another irregularly at contact points and is configured to have a wire diameter of 0.1 to 2.0 mm and a bulk density of 0.01 to 0.15 g/cm.sup.3. The three-dimensional net-like structure 101 has a width M of 60 to 200 cm, a length L of 90 to 220 cm, and a thickness of 10 to 100 cm.

[0045] As shown in FIGS. 1 to 4, the three-dimensional net-like structure 101 has a first three-dimensional sparse/dense structure 1 provided as an alternately layered configuration of structural units 1a.sub.1 to 1a.sub.9 that are sparse in an extrusion direction Y and structural units 1b.sub.1 to 1b.sub.8 that are dense in the extrusion direction Y. In this first three-dimensional sparse/dense structure 1, a bulk density .sub.1 of the sparse structural units 1a.sub.1 to 1a.sub.9 is 0.01 to 0.08 g/cm.sup.3 and a bulk density .sub.2 of the dense structural units 1b.sub.1 to 1b.sub.8 is 0.03 to 0.10 g/cm.sup.3. A ratio .sub.2/.sub.1 of the bulk density of the dense structural units 1b.sub.1 to 1b.sub.8 to the bulk density of the sparse structural units 1a.sub.1 to 1a.sub.9 is 1.01 to 5. A length A.sub.1 of the sparse structural units 1a.sub.1 to 1a.sub.9 is 1 to 30 cm, and a length A.sub.2 of the dense structural units 1b.sub.1 to 1b.sub.8 is 3 to 30 cm. A ratio A.sub.2/A.sub.1 of the length of the dense structural units 1b.sub.1 to 1b.sub.8 to the length of the sparse structural units 1a.sub.1 to 1a.sub.9 is 0.5 to 3.

[0046] As shown in FIGS. 1 to 4, the three-dimensional net-like structure 101 has a second three-dimensional sparse/dense structure 2 provided as a layered configuration of a structural unit 2c that is sparse in a thickness direction Z and structural units 2d.sub.1 and 2d.sub.2 that are dense in the thickness direction Z. In the second three-dimensional sparse/dense structure 2 applied as a core material for the care bed, a bulk density of the sparse structural unit is 0.01 to 0.08 g/cm.sup.3 and a bulk density .sub.4 of the dense structural units is 0.03 to 0.10 g/cm.sup.3. A ratio .sub.4/.sub.3 of the bulk density of the dense structural units to the bulk density of the sparse structural unit is 1.01 to 5, is preferably 1.1 to 4 and is especially preferably 1.15 to 2. A thickness of the sparse structural unit is 0.5 to 10 cm, and a thickness of the dense structural unit is 2 to 30 cm. A ratio B.sub.2/B.sub.1 of the thickness of the dense structural unit 2d to the thickness of the respective sparse structural units is 0.2 to 60. The first three-dimensional sparse/dense structure and the second three-dimensional sparse/dense structure described above provide the three-dimensional net-like structure that includes a plurality of three-dimensional intersecting regions formed by the sparse structural units. This configuration enhances the followability of the three-dimensional net-like structure 101 to a driving bottom board of the care bed.

[0047] As shown in FIG. 4, the three-dimensional net-like structure 101 has a plurality of three-dimensional sparse intersecting regions 4 including regions 4a.sub.1 to 4a.sub.9 of the lower bulk density that are formed by the respective sparse structural units of the first three-dimensional sparse/dense structure 1 and the second three-dimensional sparse/dense structure 2. The bulk density of these regions is lower than the bulk density of the structural units 2d.sub.1 and 2d.sub.2 and the bulk density of regions 4b.sub.1 to 4b.sub.8 that are included in the plurality of three-dimensional sparse intersecting regions 4 and that are respectively placed between the adjacent regions 4a.sub.1 to 4a.sub.9. The above embodiment describes the three-layered configuration. The above description is, however, also applicable to a two-layered sparse/dense configuration or to a four- or more-layered sparse/dense configuration.

[0048] With regard to a detailed manufacturing method of the three-dimensional net-like structure, refer to commonly assigned patent publications, for example, JP 4350286B and U.S. Pat. No. 7,625,629B. The sparse and dense configuration of the first three-dimensional sparse/dense structure is basically formed by varying the speed of a roller or a caterpillar member. The sparse and dense configuration of the second three-dimensional sparse/dense structure or a third three-dimensional sparse/dense structure is formed by regulating the number of nozzle holes per unit area and/or the diameter of the nozzle hole.

[0049] The following describes a three-dimensional net-like structure 201 for a care bed according to a second embodiment with reference to FIG. 5. This three-dimensional net-like structure 201 basically has a similar configuration to that of the three-dimensional net-like structure 101. The following accordingly describes difference from the first embodiment with employing the illustration and the description of the first embodiment with regard to a common configuration. The second embodiment is configured to have sparse structural units 2c.sub.1 and 2c.sub.2 and a dense structural unit 2d by changing the positions of the sparse and dense structures in the thickness direction Z from the positions of the sparse structural unit 2c and the dense structural units 2d.sub.1 and 2d.sub.2 of the second three-dimensional sparse/dense structure 2 of the first embodiment. According to the second embodiment, the dense structural unit 2d forms an intermediate layer, and the sparse structural units 2c.sub.1 and 2c.sub.2 are provided on surface layer sides. Providing the sparse structural units 2c.sub.1 and 2c.sub.2 as the surface layers enhances the followability to the care bed. Forming the dense structural unit 2d as the intermediate layer prevents separation of the fused portions of the filaments of the sparse structural unit 2c.sub.1 and also enhances the followability to the care bed.

[0050] As shown in FIG. 5, the three-dimensional net-like structure 201 has a second three-dimensional sparse/dense structure 2 provided as a layered configuration of the structural units 2c.sub.1 and 2c.sub.2 that are sparse in the thickness direction Z and the structural unit 2d that is dense in the thickness direction Z. In this second three-dimensional sparse/dense structure 2, a bulk density .sub.3 of the sparse structural units 2c is 0.01 to 0.08 g/cm.sup.3 and a bulk density .sub.4 of the dense structural unit 2d is 0.03 to 0.10 g/cm.sup.3. A ratio .sub.4/.sub.3 of the bulk density of the dense structural unit 2d to the bulk density of the sparse structural units 2c.sub.1 and 2c.sub.2 is 1.01 to 5, is preferably 1.1 to 4 and is especially preferably 1.15 to 2. A thickness B.sub.1 of the sparse structural units 2c.sub.1 and 2c.sub.2 is 0.5 to 10 cm, and a thickness B.sub.2 of the dense structural unit 2d is 2 to 30 cm. A ratio B.sub.2/B.sub.1 of the thickness of the dense structural unit 2d to the thickness of the respective sparse structural units 2c.sub.1 and 2c.sub.2 is 0.2 to 60. Providing the sparse configuration on the surface layer sides and the dense configuration as the intermediate layer in appropriate ranges of the bulk densities enables the three-dimensional net-like structure 101 to be bent readily. The above embodiment describes the three-layered configuration. The above description is, however, also applicable to a two-layered sparse/dense configuration or to a four- or more-layered sparse/dense configuration.

[0051] The following describes a three-dimensional net-like structure 201 provided according to a modification of the three-dimensional net-like structure 201 of the second embodiment. As shown in FIG. 6, in order to enhance the followability to the care bed, dense structural units 2d.sub.1 and 2d.sub.2 are respectively provided on an upper surface and a lower surface of the dense structural unit 2d. The structural units 2d.sub.1 and 2d.sub.2 are provided as high density layers having a higher bulk density than a bulk density of an intermediate layer placed between the structural units 2d.sub.1 and 2d.sub.2 in a vertical direction. The structural units 2d.sub.1 and 2d.sub.2 may be provided on respective sides of the dense structural unit 2d, or only one structural unit 2d.sub.1 or 2d.sub.2 may be provided on a single side.

[0052] The following describes a three-dimensional net-like structure 301 for a care bed according to a third embodiment with reference to FIGS. 7 to 11. This three-dimensional net-like structure 301 basically has a similar configuration to that of the three-dimensional net-like structure 201. The following accordingly describes difference from the second embodiment with employing the illustration and the description of the second embodiment with regard to a common configuration. The difference is that a third three-dimensional sparse/dense structure 3 is additionally formed in the three-dimensional net-like structure of the second embodiment. Although this embodiment basically employs the configuration of the second embodiment, the configuration of the first embodiment may alternatively be employed. The third three-dimensional sparse/dense structure is provided by changing the diameter of the nozzle hole and/or by varying the number of nozzle holes.

[0053] The three-dimensional net-like structure 301 has the third three-dimensional sparse/dense structure 3 provided as a layered configuration of a structural unit 3e that is sparse in a direction X perpendicular to the extrusion direction Y and structural units 3f.sub.1 and 3f.sub.2 that are dense in the direction X. In this third three-dimensional sparse/dense structure 3, a bulk density .sub.5 of the sparse structural unit 3e is 0.009 to 0.08 g/cm.sup.3 and a bulk density .sub.6 of the dense structural unit 3f.sub.1 and 3f.sub.2 is 0.0128 to 0.10 g/cm.sup.3. A ratio .sub.6/.sub.5 of the bulk density .sub.6 of the dense structural units 3f.sub.1 and 3f.sub.2 to the bulk density .sub.5 of the sparse structural units 3e is 1.01 to 5, is preferably 1.03 to 4 and is especially preferably 1.05 to 3. A width C.sub.1 of the sparse structural unit 3e is 40 to 100 cm, and a width C.sub.2 of the respective dense structural units 3f.sub.1 and 3f.sub.2 is 4 to 30 cm. A ratio C.sub.2/C.sub.1 of the width of the respective dense structural units 3f.sub.1 and 3f.sub.2 to the width of the sparse structural unit 3e is 0.02 to 30.

[0054] The configuration of the three-dimensional net-like structure 301 holds the human body from the respective sides to restrict a lateral motion of the human body, in addition to enhancing the followability to the care bed.

[0055] The following describes a three-dimensional net-like structure 401 for a care bed according to a fourth embodiment with reference to FIGS. 12 to 17. This three-dimensional net-like structure 401 basically has a similar configuration to that of the three-dimensional net-like structure 301. The following accordingly describes difference from the third embodiment with employing the illustration and the description of the third embodiment with regard to a common configuration. The difference is that another sparse structure is added to the third three-dimensional sparse/dense structure 3 of the three-dimensional net-like structure of the third embodiment. Although this embodiment basically employs the configuration of the third embodiment, the configuration of the first embodiment may alternatively be employed.

[0056] The three-dimensional net-like structure 401 has a third three-dimensional sparse/dense structure 3 provided as an alternately layered configuration of structural units 3e.sub.1, 3e.sub.2 and 3e.sub.3 that are sparse in the direction X perpendicular to the extrusion direction Y and structural units 3f.sub.1 and 3f.sub.2 that are dense in the direction X. In this third three-dimensional sparse/dense structure 3, bulk densities .sub.5 of the sparse structural units 3e.sub.1, 3e.sub.2 and 3e.sub.3 are 0.009 to 0.07 g/cm.sup.3 and a bulk density .sub.6 of the dense structural unit 3f.sub.1 and 3f.sub.2 is 0.0128 to 0.09 g/cm.sup.3. The bulk densities of the sparse structural units 3e.sub.1 and 3e.sub.2 are set to be lower than the bulk density of the sparse structural unit 3e.sub.3. A ratio .sub.6/.sub.5 of the bulk density .sub.6 of the dense structural units 3f.sub.1 and 3f.sub.2 to the bulk densities .sub.5 of the sparse structural units 3e.sub.1, 3e.sub.2 and 3e.sub.3 is 1.01 to 5, is preferably 1.03 to 4 and is especially preferably 1.05 to 3. A total width C.sub.1 of the sparse structural units 3e.sub.1, 3e.sub.2 and 3e.sub.3 is 40 to 100 cm. The sparse structural units 3e.sub.1 and 3e.sub.2 are set to be narrower than the sparse structural unit 3e.sub.3. A width C.sub.2 of the respective dense structural units 3f.sub.1 and 3f.sub.2 is 4 to 30 cm. A ratio C.sub.2/C.sub.1 of the width of the respective dense structural units 3f.sub.1 and 3f.sub.2 to the total width of the respective sparse structural units 3e.sub.1, 3e.sub.2 and 3e.sub.3 is 0.02 to 30.

[0057] As shown in FIG. 17, as one example, the three-dimensional net-like structure 401 for the care bed may hold the human body from respective sides to restrict a lateral motion of the human body.

Example 1

[0058] The following describes conditions of an extruding machine and a drawing machine used to manufacture a three-dimensional net-like structure for a care bed that is made of polyethylene as a material. A three-dimensional net-like structure having a capillary diameter (nozzle diameter) of 1.6 mm , a thickness of 80 mm, a width of 83 cm and a length of 195 cm corresponding to a second three-dimensional sparse/dense structure was manufactured by an extruding machine having a screw diameter of 90 mm. The following shows the ranges of the drawing speed and the bulk density that provide a three-dimensional net-like structure bent preferably at a screw rotation speed of 44.0 rpm (at an extrusion amount of about 125 kg per hour). The drawing speed of the drawing machine with regard to a first three-dimensional sparse/dense structure is 8.93 mm/sec for the dense structural units and 9.80 mm/sec for the sparse structural units. Controlling the drawing speed provides the first three-dimensional sparse/dense structure. In the first three-dimensional sparse/dense structure having a surface layer, the surface layer having a bulk density of 0.05 g/cm.sup.3 and a filament diameter of 0.7 mm provided the preferably bent three-dimensional net-like structure. This combination of the bulk density and the filament diameter enables a second three-dimensional sparse/dense structure to be provided in the three-dimensional net-like structure by changing the nozzle diameter, the number of nozzle holes and the like to vary the bulk density in the thickness direction.

[0059] The three-dimensional net-like structure described above has the first three-dimensional sparse/dense structure provided as an alternately layered configuration of sparse structural units having a bulk density of 0.050 g/cm.sup.3 and dense structural units having a bulk density of 0.055 g/cm.sup.3 at intervals of 5 cm in the extrusion direction. The second three-dimensional sparse/dense structure includes, in the thickness direction, a sparse structural unit provided to have a bulk density of 0.048 g/cm.sup.3 in a thickness of 2 cm as a surface layer and an adjacent dense structural unit provided to have a bulk density of 0.054 g/cm.sup.3 in a thickness of 6 cm. The three-dimensional net-like structure of the present disclosure was applied to a mattress (made of polyethylene), and a check test was performed to check the followability of this mattress to a bed. A bed manufactured by PLATZ Co., Ltd. (P100-3) was used to measure the followability of the mattress to the bed. The bed was configured to be angle adjustable at two positions, i.e., at a back portion and at a hip portion. The angle of the back portion was set to 40 degrees, and the angle of the hip portion was set to 20 degrees. A vertical distance between a driving bottom board of the bed and a bottom face of the mattress was measured at the hip portion. In the mattress of the three-dimensional net-like structure according to the present disclosure, the maximum value of the vertical distance from the driving bottom board of the care bed to the bottom face of the mattress was 4.6 cm. Reduction of the distance enhances the followability. The followability in X, Y and Z directions to a bed FB640 manufactured by France Bed Co., Ltd. was also checked with regard to a structure provided with a third three-dimensional sparse/dense structure including dense structural units provided to have a bulk density of 0.080 g/cm.sup.3 in a width of 6 cm on respective ends in the direction X perpendicular to the extrusion direction and a sparse structural unit provided to have a bulk density of 0.053 g/cm.sup.3 in a width of 71 cm in between. This check test gave a similar result.

Comparative Example 1

[0060] A polyethylene mattress of a three-dimensional net-like structure having the same dimensions as those in Example 1 had a bulk density of 0.050 g/cm.sup.3 in a head portion having a length of 65 cm, a bulk density of 0.055 g/cm.sup.3 in a back portion subsequent to the head portion having a length of 65 cm, and a bulk density of 0.050 g/cm.sup.3 in a leg portion subsequent to the back portion having a length of 65 cm in the longitudinal direction Y of the mattress. As the manufacturing conditions, the drawing speed was controlled in the same manner as that of Example 1, and the density of the nozzle holes was fixed. A bed manufactured by PLATZ Co., Ltd. (P100-3) was used to measure the followability of the mattress to the bed. In the mattress of this three-dimensional net-like structure, the maximum value of the vertical distance from the driving bottom board of the care bed to the bottom face of the mattress was 6 cm. This value was larger than the value of Example 1 by 1.4 cm. This indicates the poorer followability.

INDUSTRIAL APPLICABILITY

[0061] The three-dimensional net-like structure of the present disclosure is employed for a care bed having a driving bottom board that is driven by a motor.

REFERENCE SIGNS LIST

[0062] 1 . . . three-dimensional sparse/dense structure [0063] 1a.sub.1 to 1a.sub.9 . . . structural units [0064] 1b.sub.1 to 1b.sub.8 . . . structural units [0065] 2 . . . three-dimensional sparse/dense structure [0066] 2c . . . structural unit [0067] 2c.sub.1, 2c.sub.2 . . . structural units [0068] 2d . . . structural unit [0069] 2d.sub.1, 2d.sub.2 . . . structural units [0070] 3 . . . three-dimensional sparse/dense structure [0071] 3e.sub.1, 3e.sub.2 . . . structural units [0072] 3f.sub.1 to 3f.sub.3 . . . structural units [0073] 4a.sub.1 to 4a.sub.9 . . . regions [0074] 4b.sub.1 to 4b.sub.8 . . . regions [0075] 101 . . . three-dimensional net-like structure [0076] 201 . . . three-dimensional net-like structure [0077] 201 . . . three-dimensional net-like structure [0078] 301 . . . three-dimensional net-like structure [0079] 401 . . . three-dimensional net-like structure [0080] 501 . . . three-dimensional net-like structure