JP7512228B2 - Automotive seat pads - Google Patents

Description

The present invention relates to an automobile seat pad, and more specifically to an automobile seat pad whose deflection amount at low load is equivalent to that of conventional products, but whose deflection amount at medium load (200N to 600N) is smaller than that of conventional products.

2. Description of the Related Art Automobile seats are classified into two types: one in which the seat cushion (seating surface) and the seat back (back surface) are separate, and one in which the two are integrated.
In addition, automobile seats are generally
(a) a seat pad for receiving the weight of an occupant when the occupant is seated;
(b) a frame for supporting a seat pad;
(c) A trim cover that covers the outer surface of the seat pad.
Generally, a flexible polyurethane foam is used for the seat pad.

When an occupant sits on an automobile seat equipped with a seat pad, the seat pad is compressed in the direction of the load in proportion to the magnitude of the load applied to the seat pad. The magnitude of the load applied to the seat pad varies depending on the shape of the automobile seat, the inclination of the seat back, the part of the human body that comes into contact with the automobile seat, the posture of the occupant, etc. Therefore, if the hardness of the seat pad is constant regardless of location, the seat may become uncomfortable to sit on.

In order to solve this problem, various proposals have been made in the past.
For example, Patent Document 1 discloses a vehicle seat that includes a seat pad that receives the weight of a seated occupant and a support member that supports the seat pad from the underside, with recesses and protrusions formed on the underside of the seat pad.
The same document states:
(A) When a recess and a protrusion are provided on the back surface of the seat pad, the hardness of the seat pad is low at the beginning of the deflection because the contact area with the support member is small, whereas the hardness of the seat pad increases as the deflection progresses because the contact area with the support member increases; and
(B) This improves the comfort of the seat.
is stated.

Furthermore, Patent Document 2 discloses a seat pad for a seat back, in which recesses having an opening diameter of 10 to 30 mm and a depth of 2 to 40 mm are arranged in a lattice pattern on the upper part of the seating surface side (the area with which the head of a passenger seated in the seat comes into contact).
The document describes that the softness of the seat pad can be improved by providing recessed holes arranged in a lattice pattern on the upper part of the seating surface side of the seat pad.

As described in Patent Documents 1 and 2, when the back or front surface of the seat pad is formed with irregularities, the deflection at low load can be increased (in other words, the hardness at low load can be reduced) compared to when the back or front surface of the seat pad is not formed with irregularities. Also, the deflection (hardness) of the seat pad with irregularities approaches that of a seat pad without irregularities as the load increases.
However, there has been no prior art proposal for an automobile seat pad that has a deflection amount equivalent to that of conventional products under low loads and a deflection amount smaller than that of conventional products under medium loads.

JP 2014-223111 A JP 2016-002344 A

The problem that this invention aims to solve is to provide an automobile seat pad that has the same amount of deflection under low load as conventional products, but has a smaller amount of deflection under medium load than conventional products.

In order to solve the above problems, the present invention provides a seat pad for an automobile, comprising:
A main body made of soft polyurethane foam;
A fibrous sheet layer including a fibrous sheet joined to the back surface of the main body,
The fibrous sheet layer has an uneven structure including a plurality of recesses and a plurality of protrusions.

When a fibrous sheet is bonded to the back surface of a main body made of soft polyurethane foam using integral foam molding, adhesives, etc., a fibrous sheet layer is obtained with a structure in which polyurethane, adhesives, etc. are filled into the voids in the fibrous sheet. In this case, if a fibrous sheet that includes an uneven structure is used, a fibrous sheet layer with an uneven structure is obtained, and the rigidity of that part is higher than that of a main body made only of soft polyurethane foam.

When a low load is applied to an automobile seat pad having such a structure, the amount of deflection is almost the same as that of a seat pad (standard seat pad) to which a fibrous sheet layer without a concave-convex structure is bonded, because the main body deflects under low load.
On the other hand, when a medium load is applied to an automobile seat pad having such a structure, the amount of deflection is smaller than that of the standard seat pad because the highly rigid concave-convex structure formed on the back side suppresses the deflection when a medium load is applied.
Furthermore, when a high load is applied to an automobile seat pad having such a structure, the amount of deflection may again become almost the same as that of the standard seat pad. This is because, under high load, the uneven structure on the back surface disappears due to elastic deformation, and the rigidity of the main body again becomes dominant.

Fig. 1(A) is a plan view of an automobile seat pad according to a first embodiment of the present invention, and Fig. 1(B) is a cross-sectional view taken along line A-A' in Fig. 1(A). Fig. 2(A) is a plan view of an automobile seat pad according to a second embodiment of the present invention, and Fig. 2(B) is a cross-sectional view taken along line A-A' in Fig. 2(A).

FS characteristics of the seat pads obtained in Comparative Example 1 and Examples 1 and 2. FS characteristics of the seat pads obtained in Comparative Examples 1-2 and Examples 4-5.

An embodiment of the present invention will be described in detail below.
[1. Automobile seat pad (1)]
Fig. 1(A) shows a plan view of an automobile seat pad according to a first embodiment of the present invention. Fig. 1(B) shows a cross-sectional view taken along line AA' in Fig. 1(A). In Fig. 1, an automobile seat pad (hereinafter also simply referred to as "seat pad") 10a has:
A main body 12a made of soft polyurethane foam;
and a fibrous sheet layer 14a including a fibrous sheet bonded to the rear surface of the main body 12a.

[1.1. Main body]
[1.1.1. material]
The main body 12a is made of a flexible polyurethane foam. In the present embodiment, the type of the flexible polyurethane foam constituting the main body 12a is not particularly limited, and an optimum one can be selected depending on the purpose.

[1.1.2. shape]
The back surface of the main body 12a is formed with an uneven structure so as to follow the shape of the fibrous sheet layer 14a. The details of the "uneven structure" will be described later. The shapes of the other parts of the main body 12a will be described later. There are no particular limitations on the shape, and the most suitable shape can be selected depending on the purpose.
In addition, in FIG. 1, the main body 12a is illustrated as a rectangular parallelepiped whose dimensions in the x-axis direction, the y-axis direction, and the z-axis direction are constant, but this is merely an example. In reality, main body 12a has a complex three-dimensional shape that conforms to the shape of the sheet, but in FIG. 1, the shape of main body 12a is depicted in a simplified manner for ease of viewing.

[1.2. Fibrous sheet layer]
[1.2.1. material]
The fibrous sheet layer 14a is a layer joined to the back surface of the main body 12a and includes a fibrous sheet.
The term "fibrous sheet" refers to a porous sheet including a layer in which short or long fibers made of resin are fused or intertwined. Examples of fibrous sheets include nonwoven fabrics, woven fabrics, knitted fabrics, and multi-layer sheets of nonwoven fabrics and films. In the present invention, the material of the fibrous sheet is not particularly limited, and an optimal material can be selected depending on the purpose.

The method of bonding the fibrous sheet to the main body 12a to obtain the fibrous sheet layer 14a having the uneven structure is as follows:
(a) A method in which a liquid raw material for producing a flexible polyurethane foam is poured onto a fibrous sheet having an uneven structure, and a resinification reaction and a foaming reaction are carried out (integral foam molding);
(b) A method in which a liquid raw material is poured into a lower mold with a fibrous sheet set in an upper mold, and the liquid raw material is foamed while the foamed liquid raw material is impregnated into the fibrous sheet (integral foam molding);
(c) A method of preparing a main body 12a having an uneven structure on the back surface thereof, and bonding a fibrous sheet having a shape following the shape of the back surface of the main body 12a with an adhesive;
and so on.

Regardless of which method is used, the fiber sheet layer 14a is made of a composite material in which polyurethane, adhesive, etc. are filled into the voids in the fiber sheet. Therefore, the fiber sheet layer 14a has higher rigidity than the main body 12a made of soft polyurethane foam. In addition, by bonding the fiber sheet layer 14a with an uneven structure to the back surface of the main body 12a, the amount of deflection when a medium load is applied can be reduced.
It is particularly preferable that the fibrous sheet layer 14a is bonded to the back surface of the main body 12a by integral foam molding. When the fibrous sheet layer 14a is formed by integral foam molding, the bonding can be performed simultaneously with the foam molding, so that the bonding step can be omitted. In addition, since the main body 12a and the fibrous sheet layer 14a are integrated via polyurethane, the fibrous sheet layer 14a is less likely to peel off.

[1.2.2. shape]
The fibrous sheet layer 14a includes an uneven structure for adjusting the amount of bending in the thickness direction (z-axis direction).
The "uneven structure" refers to a structure including a plurality of concave portions and a plurality of convex portions. In other words, the "uneven structure" refers to a structure in which the thickness of the seat pad 10a is increased in the in-plane direction (x-axis direction and/or A structure in which, when measured along the y-axis direction, areas (convex portions) where the thickness of the seat pad 10a is relatively thin and areas (concave portions) where the thickness of the seat pad 10a is relatively thick appear repeatedly. The height (amplitude) of the recesses or protrusions and/or the distance (wavelength) between the recesses or protrusions may be constant or may vary depending on the location.
The term "relatively thick (thin) region" refers to a region of interest that is thicker (thinner) than the surrounding regions.

As the uneven structure, for example,
(a) A structure in which a plurality of semi-cylindrical portions are arranged regularly or irregularly;
(b) A structure in which a plurality of dome portions are arranged regularly or irregularly;
and so on.
The term "regularly arranged structure" refers to a structure in which regions in which the amplitude and wavelength of concave and convex portions are the same appear repeatedly with a certain regularity.
The term "irregularly arranged structure" refers to a structure in which the amplitude and/or wavelength of the recesses and/or protrusions change irregularly, and regions having the same structure do not appear repeatedly.

The "semi-cylindrical portion" refers to a semi-cylindrical structure in which, when viewed from the thickness direction (z-axis direction), the length in the long axis direction (y-axis direction in FIG. 1) is relatively longer than the length in the short axis direction (x-axis direction in FIG. 1), and the long axis/short axis ratio is 2 or more.
The semi-cylindrical portion may be, for example, a structure obtained by dividing a cylinder, a triangular tube, a square tube, a pentagonal tube, a hexagonal tube, etc., in the axial direction. In this case, the dividing direction does not necessarily have to be parallel to the axis, and may be inclined relative to the axis. The axial end face of the semi-cylindrical portion may be open as shown in Fig. 1, or may be closed with a fibrous sheet (not shown).

A "dome portion" refers to a protruding or recessed structure in which the length in the minor axis direction is approximately equal to the length in the major axis direction when viewed from the thickness direction (z-axis direction), and the major axis/minor axis ratio is less than 2. Examples of dome portions include shell-like structures with an open bottom and an upper part that is a hemisphere, a column (such as a square column, hexagonal column, or cylinder), a semi-column (a column cut in the axial direction), or a pyramid (such as a triangular pyramid or square pyramid).

1, the fibrous sheet layer 14a has a structure in which a plurality of semi-cylindrical portions 16, 16... each having the same shape are arranged at equal intervals. Each of the semi-cylindrical portions 16, 16... has a semi-cylindrical shape with both ends open, and is joined to the back surface of the main body 12a so that the axial directions are parallel to each other. Furthermore, each of the semi-cylindrical portions 16, 16... is joined to the back surface of the main body 12a so that the concave surface faces outward (toward the back surface).
In addition, in Fig. 1, a total of three semi-cylindrical portions 16, 16... are depicted, but this is merely an example. The number of semi-cylindrical portions 16, 16... is not particularly limited, and an optimal number can be selected depending on the purpose. In addition, such an uneven structure may be formed on the entire back surface of the main body 12a, or may be formed on only a part of the back surface.

[1.2.3. Basis weight]
In this embodiment, the basis weight of the fibrous sheet is not particularly limited, and an optimal value can be selected depending on the purpose. In general, the greater the basis weight of the fibrous sheet, the smaller the amount of deflection when a medium load is applied. In order to obtain such an effect, the basis weight is preferably 80 g/ ^m2 or more. The basis weight is preferably 100 g/ ^m2 or more, and more preferably 120 g/ ^m2 or more.
On the other hand, if the basis weight of the fibrous sheet is excessive, the rigidity of the fibrous sheet layer 14a becomes too high, and the amount of deflection under medium and/or high load becomes excessively small. Therefore, the basis weight is preferably 800 g/ ^m2 or less. The basis weight is preferably 400 g/ ^m2 or less, more preferably 280 g/ ^m2 or less, and even more preferably 200 g/ ^m2 or less.

[1.3. Dimensions of each part]
The dimensions of each part of the fibrous sheet layer 14a are not particularly limited, and the optimal values can be selected according to the purpose. As shown in Fig. 1, when the fibrous sheet layer 14a is joined to the back surface of the main body 12a so that the concave surfaces of the multiple semi-cylindrical parts 16, 16 ... face outward (back surface side), it is preferable that the dimensions of each part satisfy the following conditions.

If the thickness t of the main body 12a at the upper part of the semi-cylindrical portion 16 becomes too thin, the soft feel of the polyurethane foam becomes difficult to feel when the load is low (for example, when sitting with the seat back in the upright position). Therefore, t is preferably 5 mm or more. t is preferably 7 mm or more, and more preferably 10 mm or more.
On the other hand, if t is too thick, the effect of reducing the amount of deflection when a medium load is applied (for example, when a person sits with the seat back reclined) is reduced. Therefore, t is preferably 50 mm or less. t is preferably 45 mm or less, and more preferably 40 mm or less.

If the height h of the semi-cylindrical portion 16 is too low, the effect of reducing the amount of deflection under a medium load is reduced. Therefore, h is preferably 5 mm or more. h is preferably 7 mm or more, and more preferably 10 mm or more.
On the other hand, if h is too high, the fibrous sheet layer 14a will be close to the seating surface, making it difficult to feel the softness of the polyurethane foam when the load is low. Therefore, h is preferably 20 mm or less. h is preferably 17 mm or less, and more preferably 15 mm or less.

If the width d of the semi-cylindrical portion 16 is too narrow, the range of the convex portion of the fibrous sheet layer 14a is reduced, and the effect of reducing the amount of deflection under a medium load is reduced. Therefore, d is preferably 10 mm or more. d is preferably 12 mm or more, and more preferably 15 mm or more.
On the other hand, if d is too wide, the rigidity of the seat pad 10a decreases. Therefore, d is preferably 30 mm or less. d is preferably 27 mm or less, and more preferably 25 mm or less.

If the interval p between the semi-cylindrical portions 16 becomes too narrow, the area of the surface that receives the seat pad 10a becomes small, and the rigidity of the seat pad 10a becomes low. Therefore, p is preferably 3 mm or more. p is preferably 4 mm or more, and more preferably 5 mm or more.
On the other hand, if p is too wide, the range of the convex portion is reduced, so that the rigidity of the seat pad 10a is reduced and the effect of reducing the amount of deflection under a medium load is reduced. Therefore, p is preferably 10 mm or less. p is preferably 8 mm or less, and more preferably 6 mm or less.

[1.4. Deflection Amount]
In the seat pad 10a according to the present embodiment, when the material and dimensions of each part are optimized, the seat pad 10a that satisfies the relationships of the following formulas (1) and (2) is obtained. In addition to these, it is preferable that the seat pad 10a further satisfies formula (3).
−8.5%≦ΔD/D ₀ @150 [N]≦+8.5% … (1)
−23.0%≦ΔD/D ₀ @400 [N]＜0% … (2)
−9.0%≦ΔD/D ₀ @980 [N]≦+9.0% … (3)
however,
ΔD/D ₀ @X[N]=(D@X[N]-D ₀ @X[N])×100/D ₀ @X[N],
D@X [N] is the deflection amount when a load of X [N] is applied to the automobile seat pad,
D ₀ @X [N] is the deflection amount when a load of X [N] is applied to the reference seat pad.
The reference seat pad has the same shape as the automobile seat pad and is made of the same material as the automobile seat pad, except that the reference seat pad does not have a concave-convex structure on the back surface.

Equation (1) represents the range of the rate of change (ΔD/D ₀ ) of the deflection of the seat pad 10a relative to the reference seat pad when a load of 150 [N] is applied to the seat pad 10a. The load of 150 [N] is approximately equivalent to the load applied to the seat back when an occupant sits in an automobile seat with the seat back in the upright position.
In the seat pad 10a according to the present embodiment, when the material and dimensions of each part are optimized, ΔD/D ₀ @150[N] is within the range of ±8.5%. When the material and dimensions of each part are further optimized, ΔD/D ₀ @150[N] is within the range of ±4.5%, or even within the range of ±2.5%.

Equation (2) expresses the range of the rate of change (ΔD/D ₀ ) of the deflection of the seat pad 10a with respect to the reference seat pad when a load of 400 [N] is applied to the seat pad 10a. The load of 400 [N] is approximately equivalent to the load applied to the seat back when an occupant sits in an automobile seat with the seat back reclined.
In the seat pad 10a according to the present embodiment, when the material and dimensions of each part are optimized, ΔD/D ₀ @400[N] is within the range of -23.0% or more and less than 0% (◯). When the material and dimensions of each part are further optimized, ΔD/D ₀ @400[N] is within the range of -23% or more and -2.0% or less (◯), and further within the range of -23.0% or more and -4.0% or less (◯). The symbols in parentheses are the evaluation symbols in Table 1.

Equation (3) expresses the range of the rate of change (ΔD/D ₀ ) of the deflection amount with respect to the reference seat pad when a load of 980 [N] is applied to the seat pad 10a. The load of 980 [N] is approximately equivalent to the load applied to the seat back when a vehicle collides with an obstacle while a passenger is seated in the vehicle seat with the seat back in the upright position.
In the seat pad 10a according to the present embodiment, when the material and dimensions of each part are optimized, ΔD/D ₀ @980[N] is within the range of ±9.0% (○). When the material and dimensions of each part are further optimized, ΔD/D ₀ @980[N] is within the range of ±4.5% (○), and further within the range of ±2.3% (◎). The symbols in parentheses are the evaluation symbols in Table 1.

[2. Automobile seat pad (2)]
Fig. 2(A) shows a plan view of an automobile seat pad according to a second embodiment of the present invention. Fig. 2(B) shows a cross-sectional view taken along line AA' in Fig. 2(A). In Fig. 2, an automobile seat pad (hereinafter also simply referred to as "seat pad") 10b has:
A main body 12b made of soft polyurethane foam;
and a fibrous sheet layer 14b including a fibrous sheet, which is joined to the rear surface of the main body 12b.

[2.1. Main body]
The main body 12b is made of soft polyurethane foam. As described later, the structure of the back surface of the main body 12b is different from that of the main body 12a. Other points regarding the material and shape of the main body 12b are the same as those of the first embodiment, so the description will be omitted.

[2.2. Fibrous sheet layer]
[2.2.1. material]
The fibrous sheet layer 14b is a layer bonded to the back surface of the main body 12b and includes a fibrous sheet. Other points related to the material of the fibrous sheet layer 14b are the same as those in the first embodiment, so the description will be omitted.

[2.2.2. shape]
The fibrous sheet layer 14b includes an uneven structure for adjusting the amount of bending in the thickness direction (z-axis direction). ... are regularly arranged at the vertices of an equilateral triangle. Each dome portion 20, 20... has a hemispherical shell shape. Furthermore, each dome portion 20, 20... has a concave surface facing outward ( The insulating film 12c is joined to the rear surface of the main body 12b so as to face the rear surface side of the insulating film 12c.
Other points regarding the shape of the fibrous sheet layer 14b are similar to those in the first embodiment, so a description thereof will be omitted.

[2.2.3. Basis weight]
In this embodiment, the basis weight of the fibrous sheet is not particularly limited, and an optimal value can be selected depending on the purpose. The basis weight of the fibrous sheet is the same as that of the first embodiment, so a description thereof will be omitted.

[2.3. Dimensions of each part]
The dimensions of each part of the fibrous sheet layer 14b are not particularly limited, and the optimal values can be selected according to the purpose. As shown in Fig. 2, when the fibrous sheet layer 14b is joined to the back surface of the main body 12b so that the concave surfaces of the multiple dome portions 20, 20... face outward (back surface side), it is preferable that the dimensions of each part satisfy the following conditions.

If the thickness t of the main body 12b at the top of the dome portion 20 becomes too thin, it becomes difficult to feel the softness of the polyurethane foam when a low load is applied. Therefore, t is preferably 5 mm or more. t is preferably 7 mm or more, and more preferably 10 mm or more.
On the other hand, if t is too thick, the effect of reducing the amount of deflection under a medium load is reduced. Therefore, t is preferably 50 mm or less. t is preferably 45 mm or less, and more preferably 40 mm or less.

If the height h of the dome portion 20 is too low, the effect of reducing the amount of deflection under a medium load is reduced. Therefore, h is preferably 5 mm or more. h is preferably 7 mm or more, and more preferably 10 mm or more.
On the other hand, if h is too high, the fiber sheet layer 14b is close to the seating surface, making it difficult to feel the softness of the polyurethane foam when the load is low. Therefore, h is preferably 20 mm or less. h is preferably 17 mm or less, and more preferably 15 mm or less.

If the width d of the dome portion 20 becomes too narrow, the range of the convex portion of the fibrous sheet layer 14b becomes small, and the effect of reducing the amount of deflection under a medium load becomes small. Therefore, d is preferably 10 mm or more. d is preferably 12 mm or more, and more preferably 15 mm or more.
On the other hand, if d is too wide, the rigidity of the seat pad 10b decreases. Therefore, d is preferably 30 mm or less. d is preferably 27 mm or less, and more preferably 25 mm or less.

If the spacing p of the dome portions 20 becomes too narrow, the area of the surface that receives the seat pad 10b becomes small, and the rigidity of the seat pad 10b becomes low. Therefore, p is preferably 3 mm or more. p is preferably 4 mm or more, and more preferably 5 mm or more.
On the other hand, if p is too wide, the range of the convex portion is reduced, so that the rigidity of the seat pad 10b is reduced and the effect of reducing the amount of deflection under a medium load is reduced. Therefore, p is preferably 10 mm or less. p is preferably 8 mm or less, and more preferably 6 mm or less.

[2.4. Deflection Amount]
In the seat pad 10b according to the present embodiment, by optimizing the material and dimensions of each part, the seat pad 10b that satisfies the relationship of the above-mentioned formula (1) and formula (2), or the seat pad 10b that further satisfies formula (3) in addition to the above, can be obtained. Details of formulas (1) to (3) are as described above, so explanation will be omitted.

[3. Action]
When an occupant sits in an automobile seat, if the inclination of the seat back or the occupant's posture changes, a different load may be applied to the automobile seat pad accordingly. For example, when an occupant sits in an automobile seat with the seat back in the upright position, a low load of about 150 [N] is applied to the seat back.
On the other hand, when an occupant sits in an automobile seat with the seat back reclined, a medium load of about 400 [N] is applied to the seat back.
Furthermore, when a passenger is seated in a car seat with the seat back in the upright position and the car collides with an obstacle, a high load of 980 [N] or more is applied to the seat back.

Therefore, if the hardness of the seat pad is adjusted to match the load applied when the load is low, the seat pad may bend more than necessary when the load is medium, resulting in a poor sitting experience.
On the other hand, if the hardness of the seat pad is adjusted to suit the load applied during medium loads, the seat pad may become too hard, resulting in poor seating comfort during low loads. Also, when a car is hit from behind, the seat pad becomes too hard in the high load range, which may have a negative effect on whiplash.

In contrast, if a fibrous sheet is attached to the back surface of a main body made of soft polyurethane foam using integral foam molding, adhesives, etc., a fibrous sheet layer is obtained with a structure in which polyurethane, adhesives, etc. are filled into the voids in the fibrous sheet. In this case, if a fibrous sheet that includes an uneven structure is used, a fibrous sheet layer with an uneven structure is obtained, and the rigidity of that part is higher than that of a main body made only of soft polyurethane foam.

When a low load is applied to an automobile seat pad having such a structure, the amount of deflection is almost the same as that of a seat pad (standard seat pad) to which a fibrous sheet layer without a concave-convex structure is bonded, because the main body deflects under low load.
On the other hand, when a medium load is applied to an automobile seat pad having such a structure, the amount of deflection is smaller than that of the standard seat pad because the highly rigid concave-convex structure formed on the back side suppresses the deflection when a medium load is applied.
Furthermore, when a high load is applied to an automobile seat pad having such a structure, the amount of deflection may again become almost the same as that of the standard seat pad. This is because, under high load, the uneven structure on the back surface disappears due to elastic deformation, and the rigidity of the main body again becomes dominant.

(Examples 1 to 5, Comparative Examples 1 to 2)
1. Preparation of Samples
[1.1. Examples 1 to 5]
The fibrous sheet was a nonwoven fabric with semi-cylindrical uneven structures arranged in parallel at regular intervals. The height h of the semi-cylindrical portion was 10 mm, the width d was 20 mm, and the interval p was 5 mm. The basis weight of the fibrous sheet was 140 g/ ^m2 (Example 1), 200 g/ ^m2 (Example 2), 280 g/ ^m2 (Example 3), 400 g/ ^m2 (Example 4), or 800 g/ ^m2 (Example 5).
The fibrous sheet and urethane foam were foamed together to produce a seat back pad. The area of the semi-cylindrical part was 300 mm x 200 mm at the upper part of the back. The amount of raw material poured was set to an amount that would allow the formation of a soft polyurethane foam (core density: 0.035 g/cm ³ ) with a thickness of 18 mm to 35 mm at the upper part of the semi-cylindrical part.

[1.2. Comparative Example 1]
A seat pad was produced by integral foam molding in the same manner as in Example 1, except that a flat nonwoven fabric without an uneven structure was used as the fibrous sheet.

[1.3. Comparative Example 2]
A seat pad was produced by integral foam molding in the same manner as in Example 1, except that a hard urethane foam having a thickness of 7 mm and a density of 0.15 g/cm ³ was used instead of the nonwoven fabric.

2. Test Method
The FS (Force-Strain) characteristics were evaluated in accordance with JIS K6400. A pressure plate with a diameter of 200 mm was used to press the seat pad. The load for folding back from pressure to pressure during compression of the seat pad was set to 1000 N.

3. Results
Figure 3 shows the FS characteristics of the seat pads obtained in Comparative Example 1 and Examples 1 and 2. Figure 4 shows the FS characteristics of the seat pads obtained in Comparative Examples 1 and 2 and Examples 4 and 5. Furthermore, Table 1 shows the amount of deflection of each sample. The following can be seen from Figures 3 and 4 and Table 1.

In Table 1, with respect to the amount of deflection @ 150 N, "◯" indicates that the rate of change in the amount of deflection satisfies formula (1).
Regarding the amount of deflection @ 400 N, "◯" indicates that the rate of change in the amount of deflection satisfies formula (2).
Regarding the amount of deflection @ 980 N, "◯" indicates that the rate of change in the amount of deflection satisfies formula (3), and "◎" indicates that the rate of change in the amount of deflection is within the range of ±2.3%.

In addition, in Table 1, the overall evaluation is based on the deflection amount of 400 N, and those with a deflection amount of 400 N of "○" have an overall evaluation of "○" or higher, and those with a deflection amount of 980 N of "◎" have an overall evaluation of "◎".
Furthermore, the material weight (fiber sheet/urethane) in Table 1 is the material weight (fiber sheet/urethane) for each area of the prototype seat pad (300 x 200 mm), and to determine the weight of the target area, the weight reduction in the urethane foam corresponding to the void in the semi-cylindrical section was subtracted.

(1) When a fibrous sheet having a concave-convex structure was used and the basis weight was set to 800 g/ ^m2 or less, the deflection amount at a load of 150 N (load in driving position) could be kept to 12 ± 1.0 mm.
(2) In the case of Comparative Example 1, the amount of deflection when a load of 400 [N] (the load when the seat back was reclined) was 24 mm. In contrast, in the cases of Examples 1 to 5, the amount of deflection when a load of 400 [N] was 20 to 23 mm. This means that the amount of deflection when the seat is reclined is reduced, so that the body does not sink in as much, and the body can be supported more firmly.

(3) When the weight of the fiber sheet was set to 200 g/ ^m2 or less, the amount of deflection at a load of 400 [N] was reduced, and the amount of deflection at a load of 980 [N] was almost the same as that of Comparative Example 1. This means that the deflection of the upper back increases when the car crashes, which leads to a reduction in whiplash.
(4) In the case of the seat pad (Comparative Example 2) formed by integral foaming of hard urethane foam, the amount of deflection under low and high loads was equivalent to that of Comparative Example 1, and the amount of deflection under medium load was smaller than that of Comparative Example 1. However, because the hard urethane foam is high density, the weight increased.
(5) In the case where a nonwoven fabric having a concave-convex structure is bonded to the back surface of a seat pad by integral foam molding, it was found that the FS curve can be controlled by controlling the basis weight of the nonwoven fabric. In addition, it was found that the FS curve and the deflection amount equivalent to those of Comparative Example 2 can be achieved with a lighter weight by optimizing the basis weight of the nonwoven fabric.

The above describes in detail the embodiments of the present invention, but the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention.

The automobile seat pad of the present invention can be used as a seat pad for a seat cushion or a seat back.

10a, 10b Automobile seat pad 12a, 12b Main body 14a, 14b Fibrous sheet layer 16, 18 Semi-cylindrical portion (uneven structure)
20, 22 Dome portion (uneven structure)

Claims (8)

A main body made of soft polyurethane foam;
A fibrous sheet layer including a fibrous sheet joined to the back surface of the main body,
The fibrous sheet layer has an uneven structure including a plurality of recesses and a plurality of protrusions, and has a structure in which polyurethane or an adhesive is filled into voids in the fibrous sheet layer over the entire surface of the fibrous sheet layer.
Automotive seat pad. 2. The seat pad for an automobile according to claim 1 , wherein the fiber sheet has a basis weight of 80 g/ ^m2 or more and 200 g/m2 ^or less . 3. The seat pad for an automobile according to claim 1 or 2, which satisfies the following formulas (1) and (2).
−8.5%≦ΔD/D ₀ @150 [N]≦+8.5% … (1)
−23.0%≦ΔD/D ₀ @400 [N]＜0% … (2)
however,
ΔD/D ₀ @X[N]=(D@X[N]-D ₀ @X[N])×100/D ₀ @X[N],
D@X [N] is the deflection amount when a load of X [N] is applied to the automobile seat pad,
D ₀ @X [N] is the deflection amount when a load of X [N] is applied to the reference seat pad.
The reference seat pad has the same shape as the automobile seat pad and is made of the same material as the automobile seat pad, except that the uneven structure is not formed on the back surface of the reference seat pad. 4. The seat pad for an automobile according to claim 3, further satisfying the following formula (3).
-9.0%≦ΔD/D ₀ @980[N]≦+9.0% … (3) 5. The seat pad for an automobile according to claim 1, wherein the uneven structure has a structure in which a plurality of semi-cylindrical portions are arranged. The fibrous sheet layer is joined to the back surface of the semi-cylindrical portion such that the concave surface of the semi-cylindrical portion faces outward (to the back surface side),
The thickness of the main body at the upper part of the semi-cylindrical portion is 5 mm or more and 50 mm or less,
The height of the semi-cylindrical portion is 5 mm or more and 20 mm or less,
The width of the semi-cylindrical portion is 10 mm or more and 30 mm or less,
6. The seat pad for an automobile according to claim 5, wherein the interval between the semi-cylindrical portions is 3 mm or more and 10 mm or less. The uneven structure has a structure in which a plurality of dome portions are arranged,
The dome portion is a recessed structure having a shell-like structure with an open bottom.
5. A seat pad for an automobile according to claim 1. The fibrous sheet layer is joined to the back surface so that the concave surface of the dome portion faces outward (back surface side),
The thickness of the main body at the top of the dome portion is 5 mm or more and 50 mm or less,
The height of the dome portion is 5 mm or more and 20 mm or less,
The width of the dome portion is 10 mm or more and 30 mm or less,
8. The seat pad for an automobile according to claim 7, wherein the interval between the dome portions is 3 mm or more and 10 mm or less.

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