Seat pad and method for manufacturing the same

Abstract

To provide a seat pad having excellent thermal durability and a seat pad manufacturing method for easily obtaining the seat pad.SOLUTION: The seat pad includes a cushion pad 1, which includes a soft foam 2 and a bead method foam 3 embedded in the soft foam 2. The lower face of the cushion pad 1 is formed of the lower face 2f2 of the soft foam 2.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a seat pad and a method for manufacturing a seat pad. [Background technology]

[0002] Some conventional seat pads have a seat pad body made of soft foam and a portion of the underside of the soft foam covered with a bead-method foam, thereby improving the support stability of the seat pad (see, for example, Patent Document 1). In contrast, other conventional seat pads have through holes formed in the bead-method foam, and a soft foaming material is supplied through the through holes to cover a portion of the underside of the bead-method foam with the soft foam (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-259535 [Patent Document 2] Japanese Patent Application Publication No. 2018-134360 Summary of the Invention [Problem to be solved by the invention]

[0004] In all of the above-mentioned conventional seat pads, the underside of the soft foam and the underside of the bead method foam are made to be flat and level with each other, so that the underside of the seat pad is formed by the underside of the soft foam and the underside of the bead method foam.

[0005] However, the bead-method foam is weaker against heat than the soft foam, and therefore, there is room for improvement in the heat durability of the above-mentioned conventional seat pads.

[0006] An object of the present invention is to provide a seat pad having excellent heat durability and a method for manufacturing the seat pad to easily obtain the seat pad. [Means for solving the problem]

[0007] The seat pad according to the present invention includes a cushion pad, the cushion pad including a soft foam and a bead method foam embedded in the soft foam, and the underside of the cushion pad is formed by the underside of the soft foam. The seat pad according to the present invention has excellent heat durability.

[0008] In the seat pad according to the present invention, the soft foam preferably includes an upper soft foam covering the upper surface of the bead method foam and a lower soft foam covering the lower surface of the bead method foam. In this case, the seating side is covered with the soft foam, which improves seating comfort and has excellent heat durability.

[0009] In the seat pad according to the present invention, it is preferable that the bead-method foam has a through-hole extending vertically, and the upper soft foam and the lower soft foam are connected through the through-hole formed in the bead-method foam. In this case, the seat pad according to the present invention has excellent heat durability and is easy to manufacture.

[0010] In the seat pad according to the present invention, the seat pad is preferably a seat pad for a rear seat, and the seat pad according to the present invention is particularly effective when used as a seat pad for a rear seat.

[0011] In the seat pad according to the present invention, it is preferable that the bead method foam has two under-buttocks openings and the through-hole is disposed between the two under-buttocks openings, thereby providing a rear seat seat pad that is excellent in heat durability and easy to manufacture.

[0012] In the seat pad according to the present invention, it is preferable that the soft foam is made of soft foamed polyurethane, and the bead-method foam is made of bead-method expanded polypropylene or bead-method expanded polystyrene. In this case, by using commonly used soft foam and bead-method foam, a cost-effective seat pad can be obtained.

[0013] The present invention provides a method for manufacturing a seat pad using a mold having a vent and a bead-method foam having through holes formed therein, the method comprising the steps of: placing the bead-method foam inside the mold so that a gap is formed between the mold and the bead-method foam and the through holes are offset from the vent; and, after the bead-method foam setting step, supplying the soft foam material into the mold so that the soft foam material flows through the through holes into the gap. The method for manufacturing a seat pad according to the present invention makes it easy to obtain a seat pad with excellent thermal durability.

[0014] In the method for manufacturing a seat pad according to the present invention, it is preferable to use a mold that, when the bead-method foam is placed inside the mold, forms a gap with the bead-method foam and that positions the through-holes of the bead-method foam so as to be offset from the gas vents, thereby making it easier to obtain a seat pad with excellent heat resistance.

[0015] In the method for manufacturing a seat pad according to the present invention, it is preferable to use a bead-method foam having two under-buttocks openings and the through-hole disposed between the two under-buttocks openings, which makes it easy to obtain a rear seat pad with excellent heat resistance. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a seat pad having excellent heat durability and a method for manufacturing the seat pad for easily obtaining the seat pad. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a plan view schematically illustrating a seat pad according to an embodiment of the present invention. [Figure 2] FIG. 2 is a bottom view schematically showing the seat pad of FIG. 1. [Figure 3] FIG. 2 is a side view schematically showing the seat pad of FIG. 1. [Figure 4] FIG. 2 is a rear view schematically showing the seat pad of FIG. 1. [Figure 5] 2 is a cross-sectional view showing the seat pad of FIG. 1 taken along the line XX. [Figure 6] 2 is a cross-sectional view showing the seat pad of FIG. 1 taken along the YY cross section. [Figure 7] 2 is a perspective view schematically showing the seat pad of FIG. 1 from above. FIG. [Figure 8] 2 is a perspective view showing the seat pad of FIG. 1 from below. FIG. [Figure 9] FIG. 2 is a plan view schematically showing an example of a bead-method foam included in the seat pad of FIG. 1. [Figure 10] FIG. 10 is a bottom view schematically showing the bead method foam of FIG. 9. [Figure 11] FIG. 10 is a cross-sectional view showing the ZZ cross section of the bead method foam of FIG. 9. [Figure 12] FIG. 10 is a perspective view schematically illustrating the bead method foam of FIG. 9 from above. [Figure 13] FIG. 10 is a perspective view showing the bead method foam of FIG. 9 from below. [Figure 14] 1A to 1C are diagrams for schematically illustrating a method for manufacturing a seat pad according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a seat pad and a method for manufacturing a seat pad according to an embodiment of the present invention will be described with reference to the drawings.

[0019] (seat pad) A seat pad 1 according to one embodiment of the present invention is a vehicle seat pad used in a vehicle seat (a seat for an automobile). In the following description, "upper," "lower," "left," "right," "front," and "rear" refer to directions as seen from the perspective of a person seated in the seat. In the following description, the "left-right direction" is also referred to as the "width direction." In this embodiment, "lower surface" and "bottom surface" are synonymous. In this embodiment, "rear surface" and "back surface" are also synonymous.

[0020] FIG. 1 is a plan view schematically showing the seat pad 1 from above. FIG. 2 is a bottom view schematically showing the seat pad 1 from below. FIG. 3 is a side view schematically showing the left side of the seat pad 1. FIG. 4 is a rear view schematically showing the rear side of the seat pad 1. FIG. 5 is a cross-sectional view showing the seat pad 1 along the line XX in FIG. 1.

[0021] The seat pad 1 is a seat pad including a cushion pad (a pad located under the buttocks of a seated person). With reference to FIGS. 1 to 4, in this embodiment, the seat pad 1 is a cushion pad. With reference to FIG. 5, the seat pad 1 includes a soft foam 2 and a bead-method foam 3 embedded in the soft foam 2. The underside (1f2) of the seat pad 1 is formed by the underside 2f2 of the soft foam 2. Here, the underside of the seat pad 1 is, for example, a surface formed by connecting the lowest points at any position in the front-rear and left-right directions of the seat pad 1, as viewed from the top in FIG. 2. Specifically, the entire underside 3f2 of the bead-method foam 3 is located above the underside 2f2 of the soft foam 2.

[0022] In this embodiment, the soft foam 2 includes an upper soft foam 21 covering the upper surface 3f1 of the bead method foam 3, and a lower soft foam 22 covering the lower surface 3f2 of the bead method foam 3.

[0023] FIG. 6 is a cross-sectional view showing the seat pad 1 along the YY cross section of FIG.

[0024] 6, in this embodiment, the bead method foam 3 has a through hole 31 that penetrates in the vertical direction. The upper soft foam 21 and the lower soft foam 22 are connected through the through hole 31 formed in the bead method foam 3.

[0025] In this embodiment, the upper soft foam 21 and the lower soft foam 22 are connected by a connecting portion 23 that passes through the through-hole 31. In this embodiment, the connecting portion 23 is formed by a soft foam material that is filled in the through-hole 31 together with the upper soft foam 21 and the lower soft foam 22.

[0026] In this embodiment, the seat pad 1 is a seat pad for a rear seat.

[0027] For example, referring to FIG. 1 , in this embodiment, the seat pad 1 is a cushion pad for a rear seat integrally formed with two left and right seats. In this embodiment, the seat pad 1 has two main pad portions 211. The main pad portions 211 are configured to support the buttocks and thighs of a seated occupant from below. In addition, in this embodiment, the seat pad 1 has a pair of side pad portions 212 located on the left or right side of the two main pad portions 211, protruding higher than the main pad portions 211, and configured to support the seated occupant from both the left and right sides. Furthermore, in this embodiment, the seat pad 1 has a center pad portion 213 disposed between the two main pad portions 211. In addition, in this embodiment, the seat pad 1 has an attachment portion 214 for attaching the seat pad 1 to the vehicle. Furthermore, in this embodiment, the main pad portion 211 comprises a lower thigh portion 211a configured to support the thighs of the seated person from below, and a lower buttock portion 211b located behind the lower thigh portion 211a and configured to support the buttocks of the seated person from below.

[0028] In this embodiment, the upper outer portion (top surface) of the seat pad 1 is formed of an upper soft foam 21, as shown in FIG. 1. The lower outer portion (bottom surface) of the seat pad 1 is formed of a lower soft foam 22, as shown in FIG. 2. Reference symbol A1 denotes a vehicle mounting through-hole for mounting the seat pad 1 to a vehicle. Reference symbol A2 denotes a seat belt mounting notch for mounting a seat belt. Referring to FIG. 3, in this embodiment, the side outer portions of the seat pad 1 are formed of the upper soft foam 21 and the lower soft foam 22. Referring to FIG. 4, in this embodiment, the rear outer portion of the seat pad 1 is formed of the upper soft foam 21 and the lower soft foam 22.

[0029] FIG. 7 shows a schematic view of the seat pad 1 from above. FIG. 8 shows a schematic view of the seat pad from below. As shown in these perspective views, in this embodiment, the outer surface of the seat pad 1 is formed by an upper soft foam 21 and a lower soft foam 22. In this embodiment, the bead method foam 3 can be completely embedded inside the soft foam 2. In this case, in this embodiment, no part of the underside 1f2 of the seat pad 1 shows the underside 3f2 of the bead method foam 3.

[0030] Fig. 9 shows an example of a bead method foam 3 included in the seat pad 1, schematically from above. Fig. 10 shows the bead method foam 3 of Fig. 9, schematically from below. Fig. 11 shows the bead method foam 3 of Fig. 9 in a ZZ cross section of Fig. 9. Fig. 12 shows the bead method foam 3 of Fig. 9, schematically from above. Fig. 13 shows the bead method foam 3 of Fig. 9, schematically from below.

[0031] The bead method foam 3 has two under-buttocks openings 32. The two under-buttocks openings 32 are spaced apart in the left-right direction (width direction). The through-hole 31 formed in the bead method foam 3 is located between the two under-buttocks openings 32.

[0032] In this embodiment, the bead method foam 3 constitutes the core (seat pad main body) of the seat pad 1. Referring to Figures 12 and 13, the bead method foam 3 is a flat plate material. In this embodiment, the bead method foam 3 has a through hole A1 for vehicle attachment and a notch A2 for seat belt attachment.

[0033] In this embodiment, the under-buttocks opening 32 is a through-hole. The under-buttocks opening 32 passes through the bead method foam 3 in the vertical direction. In this embodiment, the hole diameter (opening area) of the under-buttocks opening 32 is larger than the hole diameter (opening area) of the through-hole 31. However, the under-buttocks opening 32 may be a non-through recess.

[0034] The through holes 31 also penetrate the bead method foam 3 in the vertical direction. In this embodiment, the through holes 31 are round holes as shown in Figures 9 and 10. However, the through holes 31 can be through holes of various shapes, for example, polygonal holes such as square holes, or slit holes such as oval holes. The size (e.g., diameter) of the through holes 31 can be set appropriately.

[0035] In this embodiment, the bead method foam 3 has a plurality of through holes 31 formed therein. In this embodiment, the plurality of through holes 31 are arranged in a plurality of rows in each of the front-rear direction and the left-right direction. Specifically, four through holes 31 are arranged in two rows in each of the front-rear direction and the left-right direction. In this embodiment, three through holes 31 are arranged between two under-the-buttock openings 32. In this embodiment, one through hole 31 is arranged between the vehicle mounting through hole A1 and the seat belt mounting notch A2. However, the arrangement of the plurality of through holes 31 can be set as appropriate. The spacing between the plurality of through holes 31 can also be set as appropriate. Furthermore, the number of through holes 31 may be at least one.

[0036] For example, referring to FIG. 5 , the underside of the seat pad 1 is formed by the underside 2f2 of the soft foam 2. That is, the bead-method foam 3 is embedded in the soft foam 2 so that the underside 3f2 of the bead-method foam 3 is located above the underside 2f2 of the soft foam 2. In other words, the soft foam 2 covers the underside 3f2 of the bead-method foam 3 so that the underside 2f2 of the soft foam 2 protrudes above the underside 3f2 of the bead-method foam 3. Therefore, the seat pad 1 can prevent the underside 3f2 of the bead-method foam 3 from directly contacting a heat source or the like. Therefore, the seat pad 1 has excellent thermal durability. In particular, when the bead-method foam 3 is completely embedded inside the soft foam 2, no part of the underside 1f2 of the seat pad 1 is exposed to the underside 3f2 of the bead-method foam 3. Therefore, the seat pad 1 has excellent thermal durability. However, with the seat pad 1, even when an opening that leads to the underside 3f2 of the bead method foam 3 is formed in the soft foam 2, as shown near the vehicle mounting through-hole A1 in Fig. 6, an air layer is formed between the heat source and the underside 3f2 of the bead method foam 3. In this case, the air layer functions as a heat insulating layer.

[0037] In the seat pad 1, the soft foam 2 includes an upper soft foam 21 covering the upper surface 3f1 of the bead method foam 3 and a lower soft foam 22 covering the lower surface 3f2 of the bead method foam 3. In this case, the bead method foam 3, which is harder than the soft foam 2, can function as the core (seat pad main body) of the seat pad 1. This improves the support stability for the seated occupant. However, the improved support stability may cause the seated occupant to feel the hardness of the seat pad 1. In contrast, the seating side of the seat pad 1 is covered with the soft foam 2. Therefore, the seat pad 1 has excellent thermal durability while improving seating comfort.

[0038] 6, for example, in the seat pad 1, the bead method foam 3 has a through-hole 31 that penetrates in the vertical direction, and the upper soft foam 21 and the lower soft foam 22 are connected via the through-hole 31. In this case, the bead method foam 3 is placed inside a mold as an insert, and soft foam resin is supplied into the mold, thereby forming soft foam 2 on both the upper surface 3f1 and the lower surface 3f2 of the bead method foam 3. This makes the seat pad 1 excellent in heat durability and easy to manufacture.

[0039] In this embodiment, the seat pad 1 is a seat pad for a rear seat. Generally, heat source devices that generate high heat, such as a battery or an engine, are located under the rear seat. Therefore, the seat pad 1 is particularly effective when used as a seat pad for a rear seat, as in this embodiment.

[0040] 9, for example, in the seat pad 1, the bead method foam 3 has two under-the-buttocks openings 32, and the through-hole 31 is disposed between the two under-the-buttocks openings 32. In this case, the seat pad 1 is a rear seat seat pad that is excellent in heat durability and easy to manufacture. In addition, in this case, the hardness of the under-the-buttocks portion of the seat pad 1 is kept low, ensuring comfort when sitting.

[0041] In the seat pad 1, the soft foam 2 may be any soft foam having elasticity. An example of the soft foam 2 is soft foamed polyurethane. In the seat pad 1, the bead method foam 3 may be any foam that is harder and more elastic than the soft foam 2. Examples of the bead method foam 3 include olefin resins, specifically, bead method expanded polypropylene (EPP) and bead method expanded polystyrene (EPS). Here, the "bead method foam" refers to a foam obtained by the so-called bead method. A bead method foam is obtained by main foaming of pre-expanded foam beads in a mold.

[0042] In the seat pad 1, the soft foam 2 is preferably made of soft polyurethane foam, and the bead-method foam 3 is preferably made of bead-method expanded polypropylene or bead-method expanded polystyrene. In this case, the use of commonly used soft foam materials and bead-method expanded polystyrene materials results in a cost-effective seat pad. In particular, when the bead-method foam 3 is made of bead-method expanded polystyrene, the thermal durability of the bead-method expanded polystyrene is lower than that of other bead-method foams. Therefore, when the bead-method foam 3 is made of bead-method expanded polystyrene, applying the present invention is effective in improving the thermal durability.

[0043] (Seat pad manufacturing method) Next, a method for manufacturing a seat pad according to one embodiment of the present invention will be described. This manufacturing method can be suitably used to manufacture the seat pad 1 described with reference to Figs.

[0044] 14, a method for manufacturing a seat pad according to this embodiment (hereinafter also referred to as "this manufacturing method") uses a mold 10 provided with a venting section 11 and a bead-method foam 3 formed with through-holes 31 to obtain a seat pad in which the outer surfaces (3f1, 3f2) of the bead-method foam 3 where the through-holes 31 are open are covered with a soft foam 2. This manufacturing method includes a bead-method foam setting step of placing the bead-method foam 3 inside the mold 10 so that a gap S is formed between the mold 10 and the bead-method foam 3 and the through-holes 31 of the bead-method foam 3 are offset from the venting section 11, and a foam material supplying step of supplying a soft foam material into the mold 10 after the bead-method foam setting step has been completed so that the soft foam material flows through the through-holes 31 of the bead-method foam 3 toward the gap S.

[0045] In this manufacturing method, "offset" refers to not overlapping the venting section 11 of the molding die 10 with the through-holes 31 of the bead method foam 3, as shown in Figure 14. This prevents the material (resin material) supplied through the through-holes 31 of the bead method foam 3 from flowing directly through the venting section 11 of the molding die 10. The venting section 11 can be, for example, a through-hole formed in the molding die 10.

[0046] In this manufacturing method, the interior of the mold 10 refers to a cavity C formed inside the mold 10. The mold 10 has, for example, an upper mold and a lower mold. In this case, the cavity C is formed by mating the upper mold and the lower mold. The cavity C forms the outer shape of the seat pad 1. The interior of the mold 10 also includes a gap S formed between the mold 10 and the bead method foam 3.

[0047] In this manufacturing method, a bead-method foam 3 having through-holes 31 formed therein is placed as an insert in the cavity C of the mold 10, and a soft foam material is supplied to the cavity C of the mold 10. This allows soft foams 2 (21, 22) to be formed on both the upper surface 3f1 and the lower surface 3f2 of the bead-method foam 3. The lower soft foam 22 covering the lower surface 3f2 of the bead-method foam 3 is formed by the gap S formed between the mold 10 and the bead-method foam 3. Therefore, the thickness 2t (see FIG. 5 ) of the lower soft foam 22 can be increased by widening the spacing Ts of the gap S. Conversely, the thickness t2 of the lower soft foam 22 can be decreased by narrowing the spacing Ts of the gap S.

[0048] On the other hand, when the soft foam material is supplied to the cavity C of the molding die 10, if the air generated in the cavity C of the molding die 10 is not properly released, the soft foam material will not be filled, which may result in underfill of the molded product (seat pad 1). For this reason, it is preferable to form a gas release portion 11 in the molding die 10.

[0049] However, even when a molding die 10 having a gas vent 11 formed therein is used, underfill still occurs in the molded product.

[0050] Therefore, as a result of intensive testing and research, the inventors have recognized that in most cases where underfill occurs in a molded product, the gas venting section 11 formed in the molding die 10 is positioned in alignment with the through hole 31 formed in the bead method foam 3, and have found that the reason for this underfill occurring is that the soft foam material supplied through the through hole 31 in the bead method foam 3 immediately seals the gas venting section 11, which is positioned in alignment with the through hole 31, as it foams.

[0051] According to this manufacturing method, as described above, when the bead method foam 3 is placed inside the molding die 10, the venting section 11 of the molding die 10 is positioned to be offset from the through-holes 31 of the bead method foam. In this case, even if a flexible foam material is supplied toward the gaps S through the through-holes 31 of the bead method foam 3, the flexible foam material does not immediately seal the venting section 11. Therefore, air generated inside the molding die 10, particularly in the gaps S, is efficiently released through the venting section 11. Therefore, according to this manufacturing method, it is possible to suppress underfill that may occur in a molded product and render it unusable as a product.

[0052] Therefore, this manufacturing method can easily produce a seat pad 1 with excellent heat durability. Referring to the plan view of Figure 9, the gas venting portion 11 of the molding die 10 can be laid out in various positions as long as it does not overlap with the through-holes 31 of the bead method foam 3. Furthermore, the number of gas venting portions 11 can be at least one.

[0053] In particular, in this manufacturing method, the distance Ts of the gap S is preferably in the range of 5 mm to 10 mm. In conventional methods for manufacturing seat pads, underfill is likely to occur when the distance Ts of the gap S is in the range of 5 mm to 10 mm. Therefore, when the distance Ts of the gap S is in the range of 5 mm to 10 mm, using this manufacturing method is effective in suppressing underfill.

[0054] 14, this manufacturing method uses a mold 10 in which, when a bead-method foam 3 is placed inside the mold 10, a gap S is formed between the mold 10 and the bead-method foam 3, and the gas vent 11 is positioned offset from the through-hole 31 of the bead-method foam 3. In this case, a seat pad 1 with excellent heat resistance can be more easily obtained.

[0055] 9 and 10, this manufacturing method uses a bead-method foam 3 having two under-the-buttocks openings 32 with a through-hole 31 disposed between the two under-the-buttocks openings 32. In this case, a rear seat pad with excellent heat durability can be easily obtained. Also, in this case, the hardness of the under-the-buttocks portion of the seat pad 1 is kept low, so a rear seat pad that ensures comfort when sitting can be obtained.

[0056] As described above, according to the present invention, it is possible to provide a seat pad having excellent heat durability and a method for manufacturing the seat pad for easily obtaining the seat pad.

[0057] The above merely illustrates one embodiment of the present invention, and various modifications are possible within the scope of the claims. For example, the seat pad 1 is a cushion pad, but it may be a combination of a cushion pad and a back pad. In this case, the seat pad according to the present invention can be applied to at least one of the cushion pad, back pad, and cushion pad. Furthermore, the seat pad according to the present invention can be only one of the cushion pad, back pad, and cushion pad. Furthermore, the seat pad according to the present invention can be a seat pad for a front seat. [Explanation of symbols]

[0058] 1: seat pad, 1f2: underside of seat pad, 2: soft foam, 2f2: underside of soft foam, 21: upper soft foam, 22: lower soft foam, 3: bead method foam, 3f1: upper surface of bead method foam, 3f2: underside of bead method foam, 31: through hole, 32: opening under buttocks, 10: mold, 11: gas vent, C: cavity, S: gap

Claims

1. A rear seat pad including a cushion pad, The cushion pad includes a soft foam and a bead method foam embedded in the soft foam, a lower surface of the cushion pad is formed by a lower surface of the soft foam; The bead method foam has a through hole penetrating in the vertical direction and has two under-buttocks openings, and the through hole is positioned between the two under-buttocks openings.

2. 2. The seat pad according to claim 1, wherein the soft foam includes an upper soft foam covering an upper surface of the bead method foam and a lower soft foam covering the lower surface of the bead method foam.

3. 3. The seat pad according to claim 2, wherein the upper soft foam body and the lower soft foam body are connected to each other through the through-holes formed in the bead method foam body.

4. The soft foam is made of soft foamed polyurethane, 4. The seat pad according to claim 1, wherein the bead-method foam is made of bead-method expanded polypropylene or bead-method expanded polystyrene.

5. A method for manufacturing a seat pad, comprising using a mold provided with a gas vent and a bead method foam having through holes formed therein, and covering an outer surface of the bead method foam having the through holes with a soft foam, the method comprising: a bead method foam setting step of placing the bead method foam inside the molding die such that a gap is formed between the molding die and the bead method foam and the through holes of the bead method foam are positioned offset from the gas vent; a foam material supplying step of supplying a soft foam material into the interior of the mold after the bead method foam setting step is completed so that the soft foam material passes through the through holes of the bead method foam toward the gaps.

6. A method for manufacturing a seat pad as described in claim 5, wherein the molding die used is a molding die that, when the bead-method foam is placed inside the molding die, forms a gap between the bead-method foam and the molding die, and the through holes of the bead-method foam are positioned so as to be offset from the gas vent portion.

7. A method for manufacturing a seat pad as described in claim 5 or 6, wherein the bead method foam has two under-buttocks openings and the through hole is arranged between the two under-buttocks openings.

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