JP7775100B2 - seat pad - Google Patents

Description

This disclosure relates to a seat pad.

Patent Document 1 discloses a cushioning material. The cushioning material disclosed in this document includes a small resin foam pad and a resin foam pad body layered on the upper surface of the small pad so as to cover it.

JP 2020-79089 A

In the cushioning material of this document, the small pad has a higher density than the pad itself, so when a heavy load is applied after sitting, the uneven profile of the small pad may come into contact with the buttocks, causing discomfort in the lower back.
The present disclosure has been made in consideration of the above-described circumstances, and aims to provide a seat pad that reduces discomfort to the body, such as the buttocks, and is comfortable to sit on.
The present disclosure can be realized in the following forms.

a first resin foam layer;
a second resin foam layer laminated on the pressure-receiving surface side of the first resin foam layer,
The second resin foam layer has a larger apparent density than the first resin foam layer.
and/or
The second resin foam layer has a 25% compression hardness measured in accordance with Method D defined in JIS K6400-2 (2012 edition) greater than that of the first resin foam layer.

The seat pad disclosed herein reduces discomfort to the body, especially in the buttocks, and provides a comfortable sitting experience.

FIG. 2 is an explanatory diagram schematically illustrating a cross section of an example of a seat pad. 10A to 10C are explanatory diagrams schematically showing a method for forming a seat pad. FIG. 2 is an explanatory diagram schematically illustrating a cross section of an example of a seat pad when a occupant is seated.

Here, a preferred example of the present disclosure will be described.
A seat pad in which a gap exists between the side edge portion of the first resin foam layer and the second resin foam layer.
A seat pad, wherein an uneven structure including a plurality of recesses and a plurality of protrusions is formed on the pressure-receiving surface side of the first resin foam layer.
- A seat pad in which the maximum thickness of the first resin foam layer is smaller than the maximum thickness of the second resin foam layer in a region where the first resin foam layer and the second resin foam layer have a laminated structure.

This disclosure is explained in detail below. Note that when a numerical range is indicated using "-", it includes both the lower limit and the upper limit unless otherwise specified. For example, the expression "10-20" includes both the lower limit of "10" and the upper limit of "20". In other words, "10-20" has the same meaning as "10 or greater and 20 or less."

1. Configuration of seat pad 1 The seat pad 1 includes a first resin foam layer 3 and a second resin foam layer 5 laminated on the pressure-receiving surface 3A side of the first resin foam layer 3. The first resin foam layer 3 and the second resin foam layer 5 satisfy the following (a) and/or (b):
(a) The second resin foam layer 5 has a larger apparent density than the first resin foam layer 3 .
(b) The second resin foam layer 5 has a 25% compression hardness measured in accordance with Method D defined in JIS K6400-2 (2012 edition) greater than that of the first resin foam layer 3.
By satisfying the relationship (a) and/or (b), the following effect is achieved. That is, when a heavy load is applied, the second resin foam layer 5 bends firmly. Moreover, because the first resin foam layer 3 is low-density and/or soft, the profile shape of the first resin foam layer 3, such as unevenness, is less felt by the body through the high-density and/or hard second resin foam layer 5. In other words, discomfort felt by the body in areas such as the buttocks is reduced. Therefore, for example, when the seat pad 1 is used as a seat cushion, discomfort felt by the buttocks is reduced, improving sitting comfort.
Furthermore, in the seat pad 1 of the present disclosure, even if the low-density and/or soft first resin foam layer 3 is fully flexed, the high-density and/or hard second resin foam layer 5 has some room to flex, thereby reducing the feeling of hitting the bottom.

The first resin foam layer 3 is not particularly limited as long as it is a resin foam. Examples of resin foam include urethane foam and polyolefin foam. Examples of polyolefin foam include polyethylene foam and polypropylene foam. Examples of urethane foam include soft polyurethane foam. As a material for the first resin foam layer 3, soft polyurethane foam is preferred from the viewpoint of providing good cushioning and a comfortable sitting experience. The urethane foam may be either slab urethane (slab polyurethane foam) or molded urethane (molded polyurethane foam).

The second resin foam layer 5 is not particularly limited as long as it is a resin foam. Examples of resin foam include urethane foam and polyolefin foam. Examples of polyolefin foam include polyethylene foam and polypropylene foam. Examples of urethane foam include soft polyurethane foam. As a material for the second resin foam layer 5, soft polyurethane foam is preferred from the viewpoint of providing good cushioning and a comfortable sitting experience. The urethane foam may be either slab urethane (slab polyurethane foam) or molded urethane (molded polyurethane foam).

The apparent density of the first resin foam layer 3 (based on JIS K 7222 (2005 edition)) is preferably 50 kg/m ^or less, more preferably 43 kg/m or ^less , and even more preferably 42 kg/m or ^less , from the viewpoint of effectively reducing discomfort felt by the body, such as under the buttocks. On the other hand, from the viewpoint of maintaining the various physical properties of the first resin foam layer 3, it is preferably 30 kg/m or ^more , more preferably 38 kg/m or ^more , and even more preferably 40 kg/m or ^more . From these viewpoints, the apparent density of the first resin foam layer 3 is preferably 30 kg/m or ^more and 50 kg/m ^or less, more preferably 38 kg/m ^{or more} and 43 kg/m ^or less, and even more preferably 40 kg/m ^{or more} and 42 kg/m or less.
The apparent density of the second resin foam layer 5 (based on JIS K 7222 (2005 edition)) is preferably 40 kg/m ^{or more} , more preferably 47 kg/m ^{or more} , and even more preferably 48 kg/m ^{or more} , from the viewpoint of effectively reducing discomfort felt by the body under the buttocks and the like while reducing the feeling of hitting the bottom. On the other hand, the apparent density of the second resin foam layer 5 is preferably 60 kg/m ^or less, more preferably 53 kg/m ^{or less} , and even more preferably 52 kg/m or ^less , from the viewpoint of improving the fit. From these viewpoints, the apparent density of the second resin foam layer 5 is preferably 40 kg/m or ^more and 60 kg/m or ^less , more preferably 47 kg/m or ^more and 53 kg/m or ^less , and even more preferably 48 kg/m or ^more and 52 kg/m or ^less .

From the viewpoint of effectively reducing discomfort to the body, such as under the buttocks, the 25% compression hardness of the first resin foam layer 3 is preferably 120N or more and 200N or less, more preferably 150N or more and 170N or less, and even more preferably 155N or more and 165N or less.
The 25% compression hardness of the second resin foam layer 5 is preferably 160N or more and 240N or less, more preferably 190N or more and 210N or less, and even more preferably 195N or more and 205N or less, from the viewpoint of effectively reducing discomfort to the body under the buttocks and the like while reducing the feeling of hitting the bottom.

The first resin foam layer 3 and the second resin foam layer 5 may be laminated via the following impregnation layer. The impregnation layer is a layer formed by impregnating the foaming liquid composition (liquid raw material) of one of the first resin foam layer 3 and the second resin foam layer 5 into the other foam layer. For example, the impregnation layer is a layer formed by impregnating the first resin foam layer 3 with the foaming liquid composition (liquid raw material 14) of the second resin foam layer 5 and hardening the layer. Alternatively, the impregnation layer may be a layer formed by impregnating the second resin foam layer 5 with the foaming liquid composition (liquid raw material 14) of the first resin foam layer 3 and hardening the layer.
The seat pad 1 may not have an impregnated layer.

It is preferable that a gap 9 exists between the side edge portion 3B of the first resin foam layer 3 and the second resin foam layer 5. The reason for this is explained below. The following method is one example of a molding method for the seat pad 1. For example, a method is used in which a profiled slab urethane is placed in a mold as the first resin foam layer 3, and then the second resin foam layer 5 is molded. In this molding method, an upper mold 11 and a lower mold 13 are used, as illustrated in FIG. 2 . With the first resin foam layer 3 (slab urethane) set facedown in the upper mold 11, a liquid raw material 14 is poured into the lower mold 13, and the liquid raw material 14 is foamed to laminate the second resin foam layer 5 on the first resin foam layer 3. If the gap 9 exists, the side edge portion 3B of the first resin foam layer 3 can be held and positioned by the positioning portion 11A of the upper mold 11 when the first resin foam layer 3 is set in the upper mold 11, thereby improving the workability of the positioning operation of the first resin foam layer 3 relative to the upper mold 11. The side edge portion 3B functions as a held portion that is held by the positioning portion 11A of the upper mold 11. In the case of Fig. 2, the positioning portion 11A has a convex shape. Note that the same effect can be obtained when molded urethane is used as the first resin foam layer 3.
When the gaps 9 exist at multiple locations on the side edge portion 3B, or when the gaps 9 exist around the entire periphery of the side edge portion 3B, the positioning of the first resin foam layer 3 relative to the upper mold 11 can be performed more accurately.
Furthermore, the presence of the gap 9 between the first resin foam layer 3 and the second resin foam layer 5 can be expected to have the following effect: when a load is applied to the seat pad 1 and it is compressed, a space is secured for the first resin foam layer 3, which is softer than the second resin foam layer 5, to deform, improving the load characteristics.

As shown in FIG. 1, the seat pad 1 preferably has an uneven structure including multiple recesses 15 and multiple protrusions 17 formed on the pressure-receiving surface 3A of the first resin foam layer 3. Each of the multiple protrusions 17 compresses in response to pressure, dispersing body pressure.

The thickness T1 of the first resin foam layer 3 is not particularly limited, and may be constant over the entire surface of the first resin foam layer 3, or may not be constant over the entire surface, and if an uneven structure is formed, thick and thin parts may exist.
The maximum thickness T1max of the first resin foam layer 3 is preferably 15 mm or more, more preferably 20 mm or more, and even more preferably 25 mm or more, from the viewpoint of improving the fit of the seat pad 1. On the other hand, the maximum thickness T1max of the first resin foam layer 3 is preferably 50 mm or less, more preferably 40 mm or less, and even more preferably 35 mm or less, from the viewpoint of reducing sagging of the buttocks. From these viewpoints, the maximum thickness T1max of the first resin foam layer 3 is preferably 15 mm or more and 50 mm or less, more preferably 20 mm or more and 40 mm or less, and even more preferably 25 mm or more and 35 mm or less.
In the example shown in Fig. 1, the maximum thickness T1max of the first resin foam layer 3 is usually the thickness at a portion where the protrusions 17 are present. In Fig. 1, the protrusions 17 having the same height h are schematically shown. When the heights h of the protrusions 17 are different, the maximum thickness T1max is, for example, the thickness at a portion where the highest protrusion 17 is present, provided that the lower surface of the first resin foam layer 3 is flat.

The thickness T2 of the second resin foam layer 5 is not particularly limited, and may be constant over the entire surface of the second resin foam layer 5, or may not be constant over the entire surface, and if an uneven structure is formed, thick and thin parts may exist.
The maximum thickness T2max of the second resin foam layer 5 at the portion where the first resin foam layer 3 and the second resin foam layer 5 form a laminated structure is preferably 15 mm or more, more preferably 20 mm or more, and even more preferably 25 mm or more, from the viewpoint of reducing discomfort to the body under the buttocks, etc. On the other hand, the maximum thickness T2max of the second resin foam layer 5 is preferably 100 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less, from the viewpoint of reducing sagging of the buttocks. From these viewpoints, the maximum thickness T2max of the second resin foam layer 5 is preferably 15 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and even more preferably 25 mm or more and 70 mm or less.
In the example shown in Fig. 1, the maximum thickness T2max of the second resin foam layer 5 is usually the thickness at a portion where the recesses 15 are present. In Fig. 1, recesses 15 of the same depth are shown schematically. In the case where the recesses 15 have different depths, the maximum thickness T2max is, for example, the thickness at a portion where the deepest recess 15 is present, provided that the upper surface of the second resin foam layer 5 is flat.

The relationship between the maximum thickness T1max of the first resin foam layer 3 and the maximum thickness T2max of the second resin foam layer 5 in the region where the first resin foam layer 3 and the second resin foam layer 5 form a laminated structure is not particularly limited. The maximum thickness T1max may be smaller than the maximum thickness T2max in the region where the first resin foam layer 3 and the second resin foam layer 5 form a laminated structure, may be the same as T2max, or may be larger than T2max. For example, the ratio [maximum thickness T1max]:[maximum thickness T2max in the region where the laminated structure is formed] is preferably 2:8-8:2, more preferably 3:7-7:3, and even more preferably 4:6-6:4.
From the viewpoint of improving sitting comfort, it is preferable that the maximum thickness T1max of the first resin foam layer 3 is smaller than the maximum thickness T2max of the second resin foam layer 5 at the portion where the first resin foam layer 3 and the second resin foam layer 5 form a laminated structure.

The height h of the protrusions 17 is not particularly limited. Taking the lowest position of the recess 15 as the reference point, the height h of at least one of the protrusions 17 is preferably 10 mm or more, more preferably 12 mm or more, and even more preferably 15 mm or more, from the perspective of improving the fit of the seat pad 1. On the other hand, the height h of at least one of the protrusions 17 is preferably 30 mm or less, more preferably 27 mm or less, and even more preferably 25 mm or less, from the perspective of reducing discomfort in the buttocks and other areas of the body. From these perspectives, the height h of at least one of the protrusions 17 is preferably 10 mm or more and 30 mm or less, more preferably 12 mm or more and 27 mm or less, and even more preferably 15 mm or more and 25 mm or less. Setting the height h of all of the protrusions 17 within the above-mentioned range effectively reduces discomfort in the buttocks and other areas of the body, improves the fit, and provides particularly good sitting comfort.

There is no particular limitation on the distance W between the vertices 17A of adjacent protrusions 17. The distance W is the shortest distance between the vertices 17A. The distances W between the vertices 17A of adjacent protrusions 17 may be the same or different for all of the protrusions 17.
It is preferable that there is at least one portion where the distance W between the vertices 17A of adjacent protrusions 17 is arranged as follows: From the viewpoint of improving the fit of the seat pad 1, this distance W is preferably 10 mm or more, more preferably 15 mm or more, and even more preferably 20 mm or more. On the other hand, from the viewpoint of improving the fit of the seat pad 1, this distance W is preferably 70 mm or less, more preferably 50 mm or less, and even more preferably 40 mm or less. From these viewpoints, the distance W is preferably 10 mm or more and 70 mm or less, more preferably 15 mm or more and 50 mm or less, and even more preferably 20 mm or more and 40 mm or less. Note that, if the distance W between the vertices 17A of adjacent protrusions 17 is set within the above-mentioned range for all protrusions 17, discomfort felt by the body, such as below the buttocks, is effectively reduced, the fit is improved, and sitting comfort is particularly improved.

2. Preferred physical properties of the seat pad 1 The 15% compression hardness of the seat pad 1, measured in accordance with the E method defined in JIS K6400-2 (2012 edition), is not particularly limited. The 15% compression hardness of the seat pad 1 is preferably less than 160 N, more preferably less than 150 N, and even more preferably less than 120 N, from the viewpoint of providing a comfortable sitting experience without an excessively hard feel. The lower limit of the 15% compression hardness of the seat pad 1 is 100 N, from the viewpoint of providing a comfortable sitting experience without an excessively soft feel. From these viewpoints, the 15% compression hardness is preferably 100 N or more and less than 160 N, more preferably 100 N or more and less than 150 N, and even more preferably 100 N or more and less than 120 N.

The 40% compression hardness of the seat pad 1, measured in accordance with Method E specified in JIS K6400-2 (2012 edition), is not particularly limited. From the viewpoint of providing a comfortable sitting experience without being too hard, the 40% compression hardness of the seat pad 1 is preferably less than 300 N, more preferably less than 250 N, and even more preferably less than 220 N. The lower limit of the 40% compression hardness of the seat pad 1 is 200 N, from the viewpoint of providing a comfortable sitting experience without being too soft. From these viewpoints, the 40% compression hardness is preferably 200 N or more but less than 300 N, more preferably 200 N or more but less than 250 N, and even more preferably 200 N or more but less than 220 N.

In accordance with JIS K6400-2 (2012 edition), it is preferable that the difference between the amount of deflection when a load of 400 N is applied and the amount of deflection when a load of 100 N is applied be as follows.
The difference in the amount of deflection is preferably 22 mm or more, more preferably 32 mm or more, and even more preferably 42 mm or more, from the viewpoint of providing a good fit to the seat pad 1. The upper limit of the difference in the amount of deflection is 50 mm, from the viewpoint of not providing an excessively sinking feeling. From these viewpoints, the difference in the amount of deflection is preferably 22 mm or more and less than 32 mm, more preferably 32 mm or more and less than 42 mm, and even more preferably 42 mm or more and less than 50 mm.

In accordance with JIS K6400-2 (2012 edition) and using an ISO 6549 iron grinding plate, the amount of deflection when a load of 700 N is applied is preferably less than 52% from the perspective of achieving a comfortable feeling when sitting. The preferred lower limit of this amount of deflection is 45%. Therefore, the amount of deflection should preferably be 45% or more and less than 52%.

3. Uses of the Seat Pad 1 The uses of the seat pad 1 of the present disclosure are not limited. The seat pad 1 is particularly suitable as a seat pad 1 for vehicles (automobiles). The seat pad 1 can be suitably used for seat cushions and seat backs.

The present disclosure will be explained in more detail below using examples. The sample configurations and evaluation results are shown in Table 1. Note that the thickness of the first resin foam layer 3 in Comparative Examples 3 and 4 and Examples 1 and 2 in Table 1 corresponds to the maximum thickness T1max in Figure 1. Similarly, the thickness of the second resin foam layer 5 corresponds to the thickness T2 of the second resin foam layer 5 located above the convex portion 17 in Figure 1.

1. Structure of Resin Foam Layer 1.1 First Resin Foam Layer 3
As the first resin foam layer 3, the following two types of flexible polyurethane foam were used.
<Flexible polyurethane foam labeled "160N flexible polyurethane" in Table 1 (hereinafter also referred to as "160N flexible polyurethane")>
Apparent density (JIS K 7222 (2005 edition)): 41 kg/m ³
・25% compression hardness (JIS K6400-2 (2012 edition) D method): 160N
<Flexible polyurethane foam labeled "278N flexible polyurethane" in Table 1 (hereinafter also referred to as "278N flexible polyurethane")>
Apparent density (JIS K 7222 (2005 edition)): 50 kg/m ³
・25% compression hardness (JIS K6400-2 (2012 edition) D method): 278N

1.2 Second resin foam layer 5
As the second resin foam layer 5, the following two types of flexible polyurethane foam were used.
<Flexible polyurethane foam labeled "150N flexible polyurethane" in Table 1 (hereinafter also referred to as "150N flexible polyurethane")>
Apparent density (JIS K 7222 (2005 edition)): 49 kg/m ³
・25% compression hardness (JIS K6400-2 (2012 edition) D method): 150N
<Flexible polyurethane foam labeled "200N flexible polyurethane" in Table 1 (hereinafter also referred to as "200N flexible polyurethane")>
Apparent density (JIS K 7222 (2005 edition)): 49 kg/m ³
・25% compression hardness (JIS K6400-2 (2012 edition) D method): 200N

1.3 Preparation of Samples 1.3.1 Comparative Example 1
A plate-shaped sample having a thickness of 80 mm was prepared using 150N soft polyurethane. This sample was composed of a single layer of the second resin foam layer 5 only.

1.3.2 Comparative Example 2
A plate-shaped sample having a thickness of 80 mm was prepared using 200N soft polyurethane. This sample was composed of a single layer of the second resin foam layer 5 only.

1.3.3 Comparative Example 3
A 278N soft polyurethane (slab polyurethane foam) was used as the first resin foam layer 3. The maximum thickness T1max of the first resin foam layer 3 was 30 mm. A plurality of protrusions 17, each having a height h of 20 mm, were formed on one side of the first resin foam layer 3. The distance W between the vertices 17A of each protrusion 17 was 30 mm.
2, the preformed first resin foam layer 3 was set in an upper mold 11, and a liquid raw material 14 (soft polyurethane foam raw material) was poured into a lower mold 13 to produce a seat pad 1 having an overall thickness of 80 mm. The liquid raw material 14 was a raw material that would give a 150N soft polyurethane second resin foam layer 5.
The total thickness of the sample was 80 mm. The maximum thickness T2max of the second resin foam layer 5 was 70 mm. T2 in FIG. 1 was 50 mm.

1.3.4 Example 1
A 160N soft polyurethane (slab polyurethane foam) was used as the first resin foam layer 3. The maximum thickness T1max of the first resin foam layer 3 was 30 mm. A plurality of protrusions 17, each having a height h of 20 mm, were formed on one side of the first resin foam layer 3. The distance W between the apexes 17A of each protrusion 17 was 30 mm.
2, the preformed first resin foam layer 3 was set in an upper mold 11, and a liquid raw material 14 (soft polyurethane foam raw material) was poured into a lower mold 13 to produce a seat pad 1 having an overall thickness of 80 mm. The liquid raw material 14 was a raw material that would give a second resin foam layer 5 with a viscosity of 200N soft polyurethane.
The total thickness of the sample was 80 mm. The maximum thickness T2max of the second resin foam layer 5 was 70 mm. T2 in FIG. 1 was 50 mm.

1.3.5 Comparative Example 4
A sample was prepared in the same manner as in Comparative Example 3, except that the thickness of the second resin foam layer 5 was adjusted to make the total thickness of the sample 60 mm.

1.3.6 Example 2
A sample was prepared in the same manner as in Example 1, except that the thickness of the second resin foam layer 5 was adjusted to a total thickness of 60 mm. The maximum thickness T2max of the second resin foam layer 5 was 50 mm. T2 in Figure 1 is 30 mm.

2. Evaluation Method 2.1 Compression Hardness For each sample, the initial position of the pressure plate when a force of 5 N was applied was used to measure the 15%, 40%, and 50% compression hardness. The sample was then pre-compressed at a rate of 50 mm/min to 75% of the thickness of the test piece. The compression was then released at a rate of 50 mm/min to obtain a load-deflection curve, from which the loads at 15%, 40%, and 50% compression were determined. A pressure plate with a diameter of 200 mm was used.

The evaluation of 15% compression hardness is as follows:
A: Less than 120N, providing excellent sitting comfort.
B: 120N or more and less than 150N, and comfortable to sit on.
C: 150N or more and less than 160N, and the sitting comfort is normal.
D: 160N or more, it feels hard when sitting and is uncomfortable to sit on.

The evaluation of 40% compression hardness is as follows:
A: Less than 220N, providing excellent sitting comfort.
B: 220N or more and less than 250N, and comfortable to sit on.
C: 250N or more and less than 300N, and the sitting comfort is normal.
D: 300N or more, it feels hard when sitting and is uncomfortable to sit on.

The 50% compression hardness was used as a measure to roughly determine whether relative evaluation was possible when comparing the physical properties of samples. That is, since Comparative Examples 2 and 3 and Example 1 had the same 50% compression hardness, it was interpreted that the physical properties of these samples could be compared and evaluated. Furthermore, since Comparative Example 4 and Example 2 had approximately the same 50% compression hardness, it was interpreted that the physical properties of these samples could be compared and evaluated.

2.2 Evaluation of stroke feeling The FS (Force-Strain) characteristics were evaluated in accordance with JIS K6400. A pressure platen with a diameter of 200 mm was used to press the sample. The load applied when the sample was compressed and then decompressed was 1000 N.
The difference between the amount of deflection when a load of 400 N was applied and the amount of deflection when a load of 100 N was applied was determined and evaluated as follows.

A: The difference is 42 mm or more, and the fit when sitting is excellent.
B: The difference is 32 mm or more and less than 42 mm, and the fit when sitting is good.
C: The difference is 22 mm or more and less than 32 mm, and the fit when sitting is normal.
D: The difference is less than 22 mm, and the fit when sitting is poor.

2.3 Evaluation of bottoming load (seat and pelvis) The load at 80% deflection was determined using a pressure plate that mimicked the protruding shape of the buttocks. The evaluation was as follows:

A: Less than 400N, providing excellent sitting comfort.
B: 400N or more and less than 650N, and comfortable to sit on.
C: 650N or more and less than 700N, and the sitting comfort is normal.
D: 700N or more, it feels hard when sitting and is uncomfortable to sit on.

2.4 Evaluation of buttock sagging In accordance with JIS K6400-2 (2012 edition), the amount of deflection was measured when a load of 700 N was applied using an iron grinding plate of ISO 6549. The evaluation was as follows.

A: Less than 52%, the amount of sagging of the buttocks is small and it is comfortable to sit on.
B: 52% or more and less than 55%, the amount of sagging of the buttocks is normal, and it is comfortable to sit on.
C: 55% or more and less than 58%, the amount of depression of the buttocks is not so great, and sitting comfort is normal.
D: 58% or more, the amount of sagging of the buttocks is large and it is uncomfortable to sit on.

2.5 Evaluation of discomfort under the buttocks For the multi-layered structures of Examples 1 and 2 and Comparative Examples 3 and 4, it was confirmed whether or not the uneven profile shape of the first resin foam layer 3 would come into contact with the buttocks when sitting, causing discomfort under the buttocks.

3. Results The results are shown in Table 1.
Although not shown in Table 1, Comparative Example 1 was too soft and uncomfortable to sit on.
In Comparative Example 2, the 15% compression hardness was rated D, and the 40% compression hardness was also rated D, and the sitting comfort was poor.
In Comparative Example 3, the 40% compression hardness was rated D, and the sitting comfort was poor. Furthermore, when sitting in Comparative Example 3, the uneven profile shape of the first resin foam layer 3 contacted the buttocks, causing an uncomfortable feeling under the buttocks.
Example 1 was well-balanced in terms of 15% compression hardness, 40% compression hardness, stroke feeling, bottoming load (seat pelvis), and buttocks collapse. Furthermore, Example 1 caused almost no discomfort under the buttocks due to the uneven profile of the first resin foam layer 3 when sitting.
Comparing Comparative Example 3 and Example 1, when the loads after sitting were made equal for the 80 mm samples, the magnitude of the load at 40% compression hardness was different, with Example 1 having a lower load than Comparative Example 3. This result also confirmed that Example 1 reduces the discomfort felt under the buttocks compared to Comparative Example 3.
When comparing Comparative Example 3 and Example 1, the stroke feeling was different in the 80 mm sample, with Example 1 having a larger stroke feeling value than Comparative Example 3. From this result, it was confirmed that Example 1 is a seat that feels more flexible than Comparative Example 3, and that sitting comfort is improved.
When comparing Comparative Example 3 and Example 1, the bottoming load was different for the 80 mm sample, with Example 1 having a smaller bottoming load value than Comparative Example 3. From this result, it was confirmed that Example 1 is more effective in improving the feeling of bottoming out than Comparative Example 3, and that sitting comfort is improved.
Comparative Example 4 was evaluated as having poor stroke feeling and bottoming load (seat pelvis), indicating poor sitting comfort. Furthermore, when sitting on Comparative Example 4, the uneven profile of the first resin foam layer 3 contacted the buttocks, causing discomfort under the buttocks.
Example 2 was well-balanced in terms of 15% compression hardness, 40% compression hardness, stroke feeling, bottoming load (seat pelvis), and buttocks collapse. Furthermore, Example 2 caused almost no discomfort under the buttocks due to the uneven profile of the first resin foam layer 3 when sitting.
When comparing Comparative Example 4 and Example 2, when the loads after sitting were made equal for the 60 mm samples, the magnitude of the load at 40% compression hardness was different, with Example 2 having a lower load than Comparative Example 4. This result also confirmed that Example 2 reduces the discomfort felt under the buttocks compared to Comparative Example 4.
When comparing Comparative Example 4 and Example 2, the stroke feeling was different in the 60 mm sample, with Example 2 having a larger stroke feeling value than Comparative Example 4. From this result, it was confirmed that Example 2 is a seat that feels more flexible than Comparative Example 4, and that sitting comfort is improved.
When comparing Comparative Example 4 and Example 2, the bottoming load was different for the 60 mm sample, with Example 2 having a smaller bottoming load value than Comparative Example 4. From these results, it was confirmed that Example 2 is more effective in improving the feeling of bottoming out than Comparative Example 4, and that sitting comfort is improved.
The results of Example 2 confirmed that even a thin sample improved the comfort of sitting and improved bottoming out. Therefore, the present disclosure can also be expected to have a thin-walled effect.
In Examples 1 and 2, it was found that the buttocks did not sink as much when seated, and the area around the ischial bones had the characteristic of bending, improving support when seated and enabling the realization of a comfortable seat pad 1. Note that Figure 3 shows a schematic cross section of the seat pad 1 when seated.

4. Effects of the Examples According to the above examples, it is possible to provide a seat pad that reduces discomfort under the buttocks and provides a comfortable seating experience.

This disclosure is not limited to the examples detailed above, and various modifications and variations are possible within the scope of this disclosure.

DESCRIPTION OF SYMBOLS 1 ...Seat pad 3 ...First resin foam layer 3A ...Pressure receiving surface 3B ...Side edge portion 5 ...Second resin foam layer 9 ...Gap 11 ...Upper mold 11A ...Positioning portion 13 ...Lower mold 14 ...Liquid raw material 15 ...Concave portion 17 ...Convex portion 17A ...Apex T1 ...Thickness T1max ...Maximum thickness T2 ...Thickness T2max ...Maximum thickness h ...Height

Claims (5)

a first resin foam layer;
a second resin foam layer laminated on the pressure-receiving surface side of the first resin foam layer,
The first resin foam layer and the second resin foam layer satisfy the following (a) and/or (b),
In accordance with JIS K6400, when a pressure plate of φ200 mm is used and the load for returning from pressure to pressure during compression of the sample is set to 1000 N, the difference in the amount of deflection when a load of 400 N is applied and when a load of 100 N is applied is 22 mm or more.
A seat pad having a deflection of less than 55% measured in accordance with JIS K6400-2 (2012 edition) and using an ISO 6549 iron grinding plate with a load of 700 N applied .
(a) The second resin foam layer has a larger apparent density than the first resin foam layer, the apparent density of the first resin foam layer being 30 kg/m3 ^or more and 50 kg/m3 ^or less, and the apparent density of the second resin foam layer being 40 kg/ ^m3 or more and 60 kg/m3 ^or less.
(b) The second resin foam layer has a 25% compression hardness measured in accordance with Method D specified in JIS K6400-2 (2012 edition) that is greater than that of the first resin foam layer, and the 25% compression hardness of the first resin foam layer is 120 N or more and 200 N or less, and the 25% compression hardness of the second resin foam layer is 160 N or more and 240 N or less. a first resin foam layer;
a second resin foam layer laminated on the pressure-receiving surface side of the first resin foam layer,
a gap exists between a side edge portion of the first resin foam layer and the second resin foam layer;
The second resin foam layer has a larger apparent density than the first resin foam layer.
and/or
The second resin foam layer has a 25% compression hardness measured in accordance with Method D defined in JIS K6400-2 (2012 edition) that is greater than that of the first resin foam layer.
Seat pad. a first resin foam layer;
a second resin foam layer laminated on the pressure-receiving surface side of the first resin foam layer,
a maximum thickness of the first resin foam layer is smaller than a maximum thickness of the second resin foam layer at a portion where the first resin foam layer and the second resin foam layer form a laminated structure; and the second resin foam layer has a higher apparent density than the first resin foam layer.
and/or
The second resin foam layer has a 25% compression hardness measured in accordance with Method D defined in JIS K6400-2 (2012 edition) greater than that of the first resin foam layer. a first resin foam layer;
a second resin foam layer laminated on the pressure-receiving surface side of the first resin foam layer,
The second resin foam layer has a larger apparent density than the first resin foam layer, and the apparent density of the first resin foam layer is 30 kg/m ³ More than 50kg/m ³ The apparent density of the second resin foam layer is 40 kg/m or less. ³ More than 60kg/m ³ is less than or equal to:
The second resin foam layer has a 25% compression hardness measured in accordance with Method D defined in JIS K6400-2 (2012 edition) that is greater than that of the first resin foam layer, the 25% compression hardness of the first resin foam layer being 120 N or more and 200 N or less, and the 25% compression hardness of the second resin foam layer being 160 N or more and 240 N or less. The seat pad according to claim 1 , wherein the first resin foam layer and the second resin foam layer are laminated via an impregnated layer.