JPH07313286A - Seat cushion body - Google Patents

Abstract

PURPOSE:To provide a seat cushion body whose load-deflection characteristic can be easily controlled so that excellent comfortableness of riding can be provided. CONSTITUTION:In a seat cushion body using a cushioning material layer formed of a synthetic fiber, the cushioning material layer 1 has a thickness ranging from 50-400mm, an area ranging from 10 to 80% of the area of the surface vertical to the direction of adding a load, and a low density part 2 having a density ranging from 0.001 to 0.01g/cm<3> within a range of 10-70% of the thickness of the cushioning material layer 1 in at least one position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat cushion body, and more particularly to a seat cushion body which can easily control the load-deflection characteristic and therefore can provide excellent riding comfort.

[0002]

2. Description of the Related Art A seat cushion body is required to have not only an appropriate amount of deflection and strength and durability to support a load but also excellent riding comfort. In order to obtain excellent riding comfort, it is necessary to lower the vibration transmissibility, and for this purpose, it is necessary to reduce the dynamic spring constant of the cushioning material and the resonance point.
Conventionally, in order to satisfy these requirements, polyurethane foam has been mainly used as a cushioning material for seat cushions.

However, since urethane has a strong rubbery feeling and a cold feeling, causes a buckling feeling, is inferior in breathability and moisture permeability, and is difficult to be recycled, it has recently become a buffer made of fiber. Wood has come to be proposed. When a fiber is used as a cushioning material, its load-deflection curve generally has a downward convex curve shape as shown in FIG. 1- (I), and the inclination of the tangent line of the load-deflection curve, that is, the static spring. The constant increases monotonically and there is no inflection point. For this reason, the dynamic spring constant increases as it bends and becomes stiff, which adversely affects the riding comfort. Further, the fiber has a larger hysteresis loss rate than urethane, which also causes an increase in the dynamic spring constant.

On the other hand, the load-deflection curve of urethane is shown in FIG.
As shown in (II), it quickly rises at the beginning of applying a load, then gradually rises after passing point A, and rises sharply from point B when further loading is applied. Good sitting comfort is exhibited when used in a range where the static spring constant from point A to point B is small. Load of fiber cushioning material −
As a method for controlling the flexural property, it has been proposed to make a urethane foam and a fibrous material into multiple layers and arrange the fibers in the longitudinal direction (Japanese Patent Laid-Open No. 62-152407).

[0005]

However, in order to control the load-deflection characteristics of the cushioning material, if different materials are combined as described in the above publication, the structure becomes complicated and the manufacturing cost rises. It had the drawback of being easy.

Therefore, an object of the present invention is to provide a seat cushion body which uses only fibers for the cushioning material layer and which can easily control the load-deflection characteristic of the cushioning material.

[0007]

As a result of intensive studies to solve the above problems, the present inventors have found that a buffer material layer having a predetermined thickness and area and at least one low density portion having a low density portion are synthesized. The present inventors have found that when the fibers are used as the cushioning material layer, the load-deflection characteristics of the cushioning material can be easily controlled, and have reached the present invention.

The above object of the present invention is to provide a seat cushion body using a cushioning material layer made of synthetic fiber,
The thickness of the cushioning material layer is in the range of 50 to 400 mm, the cushioning material layer is in the range of 10 to 80% of the area of the surface perpendicular to the direction in which the load is applied, and the thickness of the cushioning material layer is 10%. Density of 0.001 to 0.01 g /
This has been achieved by a seat cushion body characterized in that it has at least one low density portion in the cm ³ range.

The present invention will be described in more detail below. In the present invention, as the non-woven fabric forming the cushioning material layer, it is possible to appropriately select and use from among known synthetic fibers, but it is preferable to use polyester fiber from the viewpoint of cost, durability and the like.

This polyester fiber comprises at least 2 of a high melting point polyester fiber and a low melting point polyester fiber.
When it is heated above the melting point of the low-melting point polyester fiber and below the melting point of the high-melting point polyester fiber, the low-melting point polyester fiber is fused and can be formed by bonding the fibers together. It is preferably used as a non-woven fabric. The difference in melting point between the two types of polyester fibers is preferably 20 ° C or more. If the difference in melting point of the polyester fiber is less than 20 ° C., the difference in softening point becomes too small, and the temperature control becomes difficult, so that the entire fiber is softened, and the shape of the fiber cannot be maintained. It becomes a plate.

The low melting point polyester fiber is not particularly limited, but preferably has a core-sheath structure,
The average fineness is in the range of 1.5 to 18d, especially 1.5 to 1
It is preferably in the range of 2d. If the average fineness of the polyester fiber is less than 1.5 d, the spinning speed is significantly reduced, and the line speed is also reduced in the nonwoven fabric process, resulting in high cost. On the contrary, if the average fineness exceeds 18d, the compression set of the cushioning material layer deteriorates.

The blending ratio of the low melting point polyester is 5 to 5
It is preferably in the range of 0%, and particularly preferably in the range of 15 to 40%. If the blending ratio of the low melting point polyester is less than 5%, the compression set deteriorates, and conversely if it exceeds 50%, the cushioning material layer becomes too hard and the cost increases.

On the other hand, the average fineness of the high melting point polyester fiber is preferably in the range of 5 to 100 d, and particularly 2
It is preferably in the range of 0 to 70d. When the average fineness of the high melting point polyester fiber is less than 5d, the compression set is deteriorated. On the contrary, when the average fineness is more than 100d, the number of fibers is decreased and the bonding points are decreased, so that the compression set is also deteriorated.

[0014] Preferably the density of the non-woven fabric comprised of fibers mentioned above are in the range of 0.02~0.2g / cm ^3, particularly preferably in the range of 0.02~0.1g / cm ³ . If the density of the non-woven fabric is less than 0.02 g / cm ³ , the rigidity and durability of the seat cushion body will deteriorate. On the other hand, if it exceeds 0.2 g / cm ³ , not only is it disadvantageous in terms of weight and cost, but it is difficult to obtain the cushioning properties required for the seat cushion body.

Although the thickness of the cushioning material layer is not particularly limited,
In particular, it is preferably in the range of 50 to 400 mm. If the thickness of the cushioning material layer is less than 50 mm, the function as the cushioning material is not exerted, and conversely, if it exceeds 400 mm, it is disadvantageous in securing head clearance and seating position too high when used in a vehicle. Become.

The apparent density including the low density portion of the cushioning material layer is not particularly limited, either, but 0.02 to 0.1 g /
It is preferably in the range of cm ³ , and particularly from 0.03 to
It is preferably in the range of 0.06 g / cm ³ . If the apparent density is less than 0.02 g / cm ³ , it is difficult to secure the strength and durability required for the seat cushion body, while if it exceeds 0.1 g / cm ³ , it becomes disadvantageous in terms of weight and cost. The apparent density including the thickness and the low density portion can be appropriately determined from the viewpoint of performance and structural restrictions such as head clearance.

In the seat cushion body of the present invention, as shown in FIG. 2, a low density portion 2 exists in a part of the cushioning material layer.
The shape of this low-density portion can be appropriately determined depending on the required performance and structure. The area of this low-density portion is 10 of the area of the surface perpendicular to the direction in which the cushioning material layer is loaded.
To 80%, and the thickness is 10 to 70% of the thickness of the cushioning material layer. Area of low density part is 10
%, Or when its thickness is less than 10%,
It becomes difficult to obtain the desired performance due to the low density portion. vice versa,
If the area exceeds 80% or the thickness exceeds 70%, it becomes difficult to obtain the rigidity of the seat cushion body.

It suffices that at least one low density portion is provided, and not only one location but a large number can be present, and the arrangement thereof can be appropriately determined. For example, FIG.
Further, as shown in (b) and (b), it is also possible to arrange the low density portion according to the shape of the buttocks. The density of this low density portion is in the range of 0.001 to 0.01 g / cm ³ . If the density of the low density portion is out of this range, it becomes difficult to control the load / deflection characteristics, and the desired performance cannot be obtained.

The material of the low density portion is not particularly limited as long as it has a cushioning property, and non-woven fabric or foam is preferably used. Nothing may be inserted in this low-density portion and the air layer may be left as it is. Especially in the case of an air layer, it is advantageous in reducing the hysteresis loss rate.

The projected area of the plane perpendicular to the load-applying direction of the low-density portion is preferably in the range of 10 to 80% of the area of the plane perpendicular to the load-applying direction. If this area is less than 10%, it becomes difficult to obtain the desired performance due to the low density portion, and conversely, it becomes difficult to obtain the rigidity as a 80% seat cushion body.

The density of the non-woven fabric is 0.02 as described above.
The range is preferably 0.2 g / cm ³ , but the density does not have to be constant as long as it is within this range, and, for example, as shown in FIG. 4, different densities may be used. The density ratio of the non-woven fabrics when the densities are different is preferably in the range of 1 to 10, but it may be determined from performance or structural constraints. When changing the density ratio, fiber blocks having different densities may be combined, or the densities may be continuously changed by needle punching or the like.

A thermoplastic resin film such as EVA or low-density polyethylene may be used for bonding between the fiber blocks, or a heat-bonded nonwoven fabric made of polyester fiber having a low melting point may be inserted as an intermediate layer. Further, the fiber blocks may not be directly bonded to each other, but may be indirectly fixed via the surrounding sheet skin.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

In each of the examples, the fiber diameter, the blending amount, and the blending amount were adjusted so that the bending amount when a load of 18 kgf was applied using a disk loader having a diameter of 200 mm was about the same as the bending amount (14.5 mm) of the comparative example. The density was adjusted.

Example 1 A nonwoven fabric composed of 70% of 40 d of high melting point polyester fiber cut to 50 mm in length and 30% of 9 d of low melting point polyester fiber cut to the same length at a temperature of 180 ° C. Molded, density 0.1 g / cm ³ , thickness 20
A card-shaped nonwoven fabric having a thickness of 35 mm and a density of 0.1 g / cm ³ was obtained. The obtained card-shaped nonwoven fabric having a thickness of 20 mm is 2 sheets (A and B), and a thickness of 35 mm
One piece (let's call it C), each area 450 × 45
It was cut to 0 mm. The center of A was punched with a 300φ punching blade (this is designated as A '). From bottom B, A ',
They were stacked in the order of C and fixed with an adhesive.

In this way, the overall size is 450 × 4.
50 × 75 mm, the size of the low density part 2 is 300φ ×
A 20 mm seat cushion body is obtained. The low density portion is the air layer, which is located 35 mm from the top surface of the cushioning material layer as shown in FIG. 5a).

Example 2 A nonwoven fabric composed of 70% of 40d high-melting point polyester fibers cut to a length of 50 mm and 30% of 9d low-melting point polyester fibers cut to the same length at a temperature of 180 ° C. Molded, density 0.1 g / cm ³ , thickness 35
A card-shaped nonwoven fabric having a thickness of 40 mm and a density of 0.1 g / cm ³ was obtained. The obtained card-shaped nonwoven fabric having a thickness of 35 mm (referred to as A) and a thickness of 40 mm (B
And each of them was cut into an area of 450 × 450 mm. The center of B was punched with a 300φ punching blade (referred to as B ′). From bottom to top B'A,
Each was fixed with an adhesive.

In this way, the overall size is 450 × 4.
50 × 75 mm, the size of the low density part 2 is 300φ ×
A 40 mm seat cushion body is obtained. The low-density portion is the air layer, which is located 35 mm from the top surface of the cushioning material layer as shown in FIG. 5b).

Example 3 A non-woven fabric composed of 60% of high melting point polyester fiber 60d cut into a length of 50 mm and 40% of low melting point polyester fiber 3d cut into a similar length was heated at a temperature of 180 ° C. Molded, density 0.1 g / cm ³ , thickness 25
A mm-shaped non-woven fabric was obtained. Each of the obtained three card-shaped nonwoven fabrics was cut into an area of 450 × 450 mm (denoted as A, B, and C). One of them (A)
The center of was punched with a 300φ punching blade (this is designated as A '). From the bottom, B, A ', and C were stacked in this order and fixed with an adhesive.

In this way, the overall size is 450 × 4.
50 × 75 mm, the size of the low density part 2 is 300φ ×
A 25 mm seat cushion body is obtained. The low-density portion is the air layer, which is located 25 mm from the upper surface of the cushioning material layer as shown in FIG. 5c).

Comparative Example 1 A nonwoven fabric composed of 70% of 40d high melting point polyester fibers cut to 50 mm length and 30% of 9d low melting point polyester fibers cut to the same length at a temperature of 180 ° C. Molded to obtain a card-shaped nonwoven fabric having a density of 0.045 g / cm ³ and a thickness of 75 mm. The obtained card-shaped nonwoven fabric was cut into an area of 450 × 450 mm. In this way, a seat cushion body having a solid structure with an overall size of 450 × 450 × 75 mm was obtained.

Physical properties of the seat cushion bodies obtained in Examples 1 to 3 and Comparative Example 1 were evaluated by the following measuring methods.

(Load-deflection characteristics) Diameter 2 on the sample
After placing a disc loader of 00 mm and compressing it to a displacement amount of 50 mm at a speed of 20 mm / min, the load is removed again to return the displacement amount to 0 at the same speed. The static spring constant and the hysteresis loss rate were obtained from the relationship between the load and the displacement obtained from a series of operations. Static spring constant is the load when the load is 18 Kgf-
It was calculated from the slope of the tangent of the deflection curve.

(Vibration characteristics) Diameter 200 m on the sample
A disc loader having a weight of 18 mg and a weight of 18 kgf was placed, a forced vibration test was performed, and a riding comfort was determined by obtaining a dynamic spring constant.

The load-deflection curves of the seat cushion bodies obtained in Examples 1 to 3 and Comparative Example 1 are shown in FIGS.
d). As shown in FIG. 6d), the load-deflection curve monotonously increases in the seat cushion body having a solid structure, and there is no inflection point. Therefore, the static spring constant also monotonically increases with the load. On the other hand, the load-deflection curve of Example 1 shows that the load starts gently and rises gently, and the deflection amount is 20 m.
The way of rising becomes steeper than around m. An inflection point exists near the amount of deflection of 20 mm, and the rate of increase of the static spring constant changes at this point.

Comparing the load-deflection curves of Example 1 and Example 2, the inflection point exists in the vicinity of the deflection amount of 20 mm in Example 1, whereas the deflection amount of 30 m in Example 2
It exists near m. From this result, it is understood that the position of the inflection point can be controlled by the thickness of the low density portion. In addition, the hysteresis loss rate decreases as the thickness of the low density portion increases.

Table 1 shows the static spring constant, the hysteresis loss rate, and the dynamic spring constant of the seat cushions obtained in Examples 1 to 3 and Comparative Example 1 above.

[0038]

[Table 1]

From the results shown in Table 1, it can be seen that the spring constant and the hysteresis loss rate are reduced by providing the low density portion.

[0040]

Since the seat cushion body of the present invention has the above-mentioned structure, it has the following effects. (1) The load-deflection characteristic can be easily controlled by providing a low-density portion in a part of the cushioning material layer. (2) The hysteresis loss rate can be reduced by providing a low density portion in a part of the buffer material layer. (3) A seat cushion body having an excellent fit can be easily obtained by adjusting the position where the low-density portion is provided to the unevenness of the body shape.

[Brief description of drawings]

FIG. 1 is a diagram showing load-deflection curves of fibers and urethane.

FIG. 2 is a low-density portion of the seat cushion body of the present invention
It is a cross-sectional schematic diagram in two cases.

FIG. 3 is a seat cushion body of the present invention in which the low-density portion is 2
It is a cross-sectional schematic diagram in two cases.

FIG. 4 is a schematic cross-sectional view when the cushioning material layer used in the seat cushion body of the present invention has two different densities.

FIG. 5 is a schematic cross-sectional view of the seat cushion body of the present invention in which an air layer is provided in a low density portion.

FIG. 6 is a diagram showing a load-deflection curve of the seat cushion body of the present invention.

[Explanation of symbols]

 1,1 'Buffer material layer (nonwoven fabric) 2 Low density part

Claims (4)

[Claims] 1. A cushioning material layer made of synthetic fiber is used.
In the seat cushion body, the thickness of the cushioning material layer is 5
It is in the range of 0 to 400 mm, and the cushioning material layer has a load.
In the range of 10 to 80% of the area of the plane perpendicular to the direction
And in the range of 10 to 70% of the thickness of the cushioning material layer.
Density is 0.001-0.01g / cm ³Low in the range
Characterized by possessing at least one density portion
Seat cushion body. 2. The seat cushion body according to claim 1, wherein the low-density portion is an air layer. 3. The projected area of a plane perpendicular to the load-applied direction of the low-density portion is 1 of the area of the plane perpendicular to the load-applied direction.
The seat cushion body according to claim 1 or 2, wherein the range is 0 to 80%. 4. The cushioning material layer is made of polyester fiber,
When the polyester fiber is blended with at least two types of fibers, a high melting point polyester fiber and a low melting point polyester fiber, and is heated above the melting point of the low melting point polyester fiber and below the melting point of the high melting point polyester fiber. 2. The seat cushion body according to claim 1, wherein the seat cushion body is a non-woven fabric that can be formed by fusing the low melting point polyester fibers and bonding the fibers to each other.