JPH10248685A - Seat main pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the irregularity in density of a fibrous elastic body, to shorten the heat forming time, and to improve flexibility and hardness in comparison with a full foam structure of fibrous elastic body, by adopting a composite structure of fibrous elastic body and urethane foam. SOLUTION: This seat main pad comprises a front pad layer 11 of fibrous elastic body and a rear pad layer 12 of urethane foam disposed at the rear of the front pad layer 11, and the front pad layer 11 is formed in a substantially regular thickness. The fibrous elastic body forming the front pad layer 11 can be molded in a substantially regular thickness. Further, the flexure property and hardness property of the urethane foam for the rear pad layer 12 can make up weak points of the fibrous elastic body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat main pad mainly used for a vehicle seat.

[0002]

2. Description of the Related Art A conventional general vehicle seat having a spring structure will be described with reference to a partially cutaway perspective view of FIG. The vehicle seat (also simply referred to as a seat) includes a seat back SB that supports the back of the occupant and a seat cushion SC that supports the buttocks of the occupant. The seat back SB and the seat cushion SC include a seat cover 1, a seat main pad 2, and a seat frame 3, respectively.

The seat cover 1 covers the surface of the seat main pad 2, expresses the design of the seat, and assists the strength of receiving the load of the occupant (so-called seat strength). The seat cover 1 generally has a three-layer structure including a skin material, a cover pad material, and a backing fabric. The skin material is a fabric made of polyester fiber, the cover pad material is an elastic body made of a fiber material such as polyurethane foam or polyester, and the backing base fabric is a thin fabric made of polyester fiber or the like.

The seat main pad 2 contributes to the cushioning and vibration absorption of the seat, in addition to forming the outer shape of the seat. The material of the seat main pad 2 is most commonly a molded pad made of molded urethane foam. In some cases, a material obtained by solidifying natural fibers such as palm rock with latex or a synthetic fiber material of a thermoplastic resin is used as a binder material of a different material. The material hardened by the above, that is, a fibrous elastic body is used. In recent years, a fiber elastic material having excellent recyclability has attracted more attention than a molded urethane foam having poor recyclability. As the fibrous elastic body, for example, a polyester fiber mixed with a low-melting polyester fiber having the same low melting point is set in a highly air-permeable mold having a seat cushion portion and a seat back portion shape, and heat is applied. Thus, a polyester fiber elastic body obtained by melting the low-melting polyester and solidifying it as a binder is used.

[0005] The seat frame 3 forms a skeleton for maintaining the shape and strength of the seat. The seat frame 3 shown in FIG. 7 incorporates a seat spring 4 and the like to provide a cushioning function and a vibration absorbing function of the seat and to reduce occupant fatigue. It has a structure that satisfies the function and the occupant hold function.

[0006] The seat provided with the seat frame 3 having the seat spring 4 is mainly found in high-grade to intermediate-grade models. On the other hand, in low-end to middle-end models such as popular models, in order to simplify the seat structure and reduce costs, the seat main pad 2 is received by the panel product seat frame 3 without the seat spring 4, A full-form structure in which many functions such as a cushion function and a vibration absorbing function are left to the seat main pad 2 is mainly used. In this case, the most spring feeling (bending amount, repulsive force) among the seat main pads 2
Polyurethane foam (also referred to as polyurethane foam) is used, but a material that replaces urethane foam has been required from the viewpoints of recyclability, mainly the effect of preventing stuffiness in summer.

Therefore, it is considered that the above-mentioned fiber elastic body, for example, polyester elastic body is suitable as a material of the seat main pad 2. The advantages of this fiber elastic body will be described. (1) Unlike the structure of the urethane foam, the structure of the fiber elastic body is such that the fibers are entangled at random and the contact points are bonded by low-melting-point binder fibers. Alternatively, it should have an excellent effect of preventing the rise of humidity on the back surface, that is, an effect of preventing stuffiness. (2) Although the surface shapes of the seat cushion SC and the seat back SB are considered so that the pressure at the time of sitting is ideally dispersed, a material having a large flexure such as urethane foam may have a different surface shape depending on the occupant's body shape. The fiber elastic body has high surface stiffness, does not easily change its surface shape even when seated, and has the characteristics of excellent sitting comfort. That The surface stiffness expresses surface characteristics required for the surface of the seat to bend on the surface when seated on the seat, and can also be referred to as surface deflection characteristics. (3) Since the polyester fiber elastic body has a nearly linear bending characteristic, it does not feel foreign matter due to the characteristic inverted S-shaped bending characteristic of the molded urethane foam. (4) The polyester fiber elastic body is made of 100% thermoplastic polyester fiber and has excellent recyclability.

[0008]

However, it is difficult to produce a sheet main pad having a full-form structure at a constant density by using a fibrous elastic body because the thickness of the sheet main pad changes. This will be described in detail below. For example, the seat main pad used for the seat cushion SC has a non-uniform thickness, and the back surface of the pad is dug out to prevent front slippage, and a submarine portion is formed by applying a panel convex portion of the seat cushion SC to this portion to form a wall. Is extremely thin, for example, about 1/2 to 1/3 of the general part, and the lower part of the occupant's lower part (the ischial tuberosity) is made thicker in consideration of the cushioning property. Changes are connected by curves.

There are two methods of forming the fibrous elastic body, a laminating method and a blowing method. Each molding method will be described. First, the forming method of the lamination method will be described with reference to FIG. FIG. 8A shows a molding machine, and FIG. 8B shows a heating molding step.
The molding die will be described with reference to FIG. 8A. The molding die includes a lower die 30 and an upper die 40 having a molding surface for forming a cavity having a predetermined shape by closing the die. Each mold surface of the lower mold 30 and the upper mold 40 is formed of a highly air-permeable punching metal having a large number of holes. Hot air is blown from the mold surface of the lower mold 30 toward the cavity, and the hot air is discharged from the mold surface of the upper mold 40.

In order to form a seat main pad using the above-mentioned forming die, a pre-forming mat 50 is set on a lower die 30 as shown in FIG. More specifically, a pre-formed mat 50 in which a plurality of materials obtained by cutting a mat material processed into a thin mat shape by previously aligning fibers in a certain direction with a card or the like from a fiber material is superimposed and adjusted to a predetermined thickness is prepared. Spread the lower mold 30 and line it up. Next, as shown in (b), the upper mold 40 is closed to the lower mold 30 and the pre-mold mat 50 is closed.
After hot pressing, hot air (see the arrow in the figure) at a temperature slightly higher than the melting point of the binder fibers (heat-fused fibers) in the pre-forming mat 50 is passed through the pre-forming mat 50 to form a molded product. I do. Thereafter, the molded article is cooled by cold air or the like, and after the binder fibers are solidified, the mold is opened and the mold is released to obtain a molded article, that is, a sheet main pad.

When the above-mentioned lamination method is used, a large change in density can be dealt with by adjusting the number of layers of the pre-formed mats 50. However, it is impossible to suppress a change in density at a joint portion due to superposition. Further, it is possible to reduce the density change by reducing the basis weight of the pre-formed mat 50 as much as possible and increasing the number of superposed mats, but this is a method of extremely low productivity.

Next, the blow molding method will be described with reference to FIG. Since this molding die is almost the same as that of the above-mentioned lamination method, the same parts are denoted by the same reference numerals and the description thereof will be omitted. This molding method is different from the lamination method in the method of loading the fiber material into the molding die. In this case, a fiber mat is directly mixed without using a fiber mat as in the above-described lamination method. That is, as shown in FIG. 9, the lower mold 30 and the upper mold 40 are mold-opened in a state of being surrounded by an enclosing frame 60 made of punched metal, and a loose fiber material 51 is blown into the internal space by air conveyance, and On the other hand, the fiber material 51 is loaded into the internal space by suction. Note that the subsequent forming steps are the same as the steps of the lamination method, and thus will be omitted.

When the blowing method is used, the cost can be reduced as compared with the laminating method, but the problem of non-uniform density increases. The reason is that when the fibrous material 51 is blown, the clearance (crushing allowance) between the lower mold 30 and the upper mold 40 is constant, so that a thin portion has an extremely high density. For example, compare product thicknesses of 100 mm and 50 mm. The packing density of the fiber material 51 is 0.01 g / cm ³ , and the target density of the product is 0.1 g / cm ³ .
When the thickness is 03 g / cm ³ , the clearance between the lower mold 30 and the upper mold 40 is twice as large as the product thickness, that is, 20 mm when the thickness is 100 mm.
In the case of 0 mm and 50 mm, 100 mm is required. now,
Together density portion of the product thickness 100 mm in 0.03 g / cm ^3, the density of the portions The 50 mm becomes a 0.05 g / cm ^3.

For the reasons described above, the fibrous elastic body can be formed by either the laminating method or the blowing method.
There is a problem that it is difficult to produce a sheet main pad having a variable density, that is, an object to be formed having an uneven shape at a constant density. From this, the fiber elastic body is
It is an unsuitable material for a full-form seat main pad. When considering the performance of the seat such as cushioning, vibration absorption and design, a seat main pad having a certain thickness cannot be considered.

Further, according to the fibrous elastic body, when the density is not uniform, the ventilation amount of the hot air for the heat molding differs depending on the density.
Since it takes a long time to heat the entire molded article to a predetermined temperature, there is a problem in that the heat molding time is long.

Further, the fibrous elastic body has a problem that the flexing property and the hardness property are inferior to those of the molded urethane foam.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object to be solved by the present invention is to employ a composite structure of a fibrous elastic body and urethane foam, thereby improving the fibrous elasticity. It is an object of the present invention to provide a seat main pad capable of reducing variations in body density, shortening the time required for thermoforming, and improving the bending characteristics and the hardness characteristics as compared with a full-form structure of a fibrous elastic body.

[0018]

According to a first aspect of the present invention, there is provided a front pad layer made of a fiber elastic material, and a back pad layer made of urethane foam provided on the back side of the front pad layer. Wherein the front pad layer is formed with a substantially constant thickness. According to the seat main pad of the first aspect, since the fibrous elastic body forming the surface pad layer can be formed with a substantially constant thickness, the variation in density can be reduced, and thereby the heat molding can be performed. Time can be reduced. In addition, by adopting a composite structure of a front pad layer made of a fibrous elastic body and a back pad layer made of urethane foam, by compensating for the weakness of the fibrous elastic body with the bending characteristics and hardness characteristics of the urethane foam, Bending characteristics and hardness characteristics can be improved as compared with a full-form structure of an elastic body.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to a seat main pad (also referred to as a seat cushion pad) of a seat cushion of a vehicle seat. FIG.
The seat main pad 10 shown in a perspective view in FIG. 2 has an upper surface shown as a seat surface 10a and a lower surface shown as a panel surface 10b as shown in a right sectional view in FIG. FIG. 5 (c) is a diagram corresponding to a front sectional view of the seat main pad, which will be described later.
Is shown upside down.

As shown in FIG. 2, the seat main pad 10
Is a surface pad layer 11 forming the seating surface 10a, and the panel surface 1 formed on the lower surface of the surface pad layer 11.
The back pad layer 12 forming the outer cushions 0b forms substantially the same outer shape as a seat cushion having a full-form structure. The back pad layer 12 is made of molded urethane foam, and is integrated with the front pad layer 11 made of a fibrous elastic body.

The front pad layer 11 is provided in the front-rear direction of the seat main pad at the lower part of the occupant's bottom (left-right direction in FIG. 2).
Is formed with a substantially constant thickness, for example, a thickness t of 30 mm from the seating surface 10a (see FIGS. 2 and 5 (c)).
Further, as shown in FIG. 5C, the back surfaces of the left and right side portions (denoted by 10S) of the front pad layer 11 are connected to the panel surface (the same reference numeral) that is continuous with the panel surface 10a of the back pad layer 12. Is described), and the thickness is large. Accordingly, the back pad layer 12 is in a state of being fitted into the concave portion 11a of the front pad layer 11.

The fiber elastic material forming the front pad layer 11 is made of, for example, a polyester fiber elastic material. The fibrous material of the fibrous elastic body is a heat-sealing type made of a matrix fiber constituting a main skeleton and a binder fiber bonding the matrix fiber, and for example, ELK (trade name) manufactured by Teijin can be used.

Next, an example of a forming process of the surface portion pad layer 11 by a lamination method will be described with reference to the explanatory view of FIG. 3A to 3D are schematic cross-sectional views showing a molding step. The molding die is almost the same as the molding die in the laminating method described in the conventional example (see FIG. 8) except that the shape of the molding surface for forming the cavity by closing the mold is different. And its description is omitted. First, in the filling step of FIG. 3A, the pre-molded mat 50 is set on the lower mold 30.
More specifically, two pre-formed mats 50 processed in the same manner as described in the conventional example (see FIG. 8) are spread over the lower mold 30.

Next, in the pressing step (b), the upper die 40 is closed to the lower die 30 and the pre-molded mat 50 is pressed. Next, in the heat molding step (c), hot air having a temperature slightly higher than the melting point of the binder fibers (heat-fused fibers) in the pre-molded mat 50, for example, 150 to 210 ° C. (see the arrow in the drawing) is applied. The molded article 100 is molded by passing through the pre-molding mat 50. Next, the molded article 100 is cooled by cold air or the like to solidify the binder fibers. Then, (d)
In the temporary demolding step, the mold is opened.

Thus, the molded article 100, that is, the surface pad layer 11 is formed. By the way, the surface pad layer 11
The two layers, namely the back pad layer 12 and the back pad layer 12, are desirably in an adhesive state so as not to shift if a shift or the like occurs in a product state, which significantly impairs the sheet performance. Therefore, it is possible to bond the front pad layer 11 and the back pad layer 12 with an adhesive, but most preferably, the front pad layer 11 is set in a molded urethane foam mold, This is a method in which the pad layer 12 is integrally foamed.
In this case, there is a problem of impregnation of urethane into the fibrous elastic body of the front pad layer 11 at the time of integral foam molding. In order to solve such a problem, in the present embodiment, the surface pad layer 1
A back film (reference numeral 13 is attached) is bonded to the back surface of 1 by the following bonding step.

The step of bonding the back film will be described with reference to the explanatory view of FIG. Preliminary demolding process (Fig. 3
4 (a), the back film 13 is set on the lower mold 30 so as to cover the back surface of the front pad layer 11 in the film setting step of FIG. As the back film 13, for example, a two-layer product of a general polyester film material and a hot melt film having a melting point of 100 to 130 ° C is used. The back film 13 is set with the hot melt film surface facing the back surface of the front pad 11.

Next, in the vacuum forming step (b),
By evacuating the mold surface of the lower mold 30, the back film 13 is attracted to the back surface of the front pad layer 11. Next, in the heating step (c), the upper mold 40 is closed and the lower mold 30 is closed.
The hot melt film of the back film 13 is melted by blowing hot air (110 to 140 ° C.) from the back, and the back film 1 is formed on the back surface of the surface pad layer 11.
3 is heat-sealed. Next, a front pad layer with a back film 13 (also referred to as a front pad layer with a film) 11.
After cooling, the mold is opened and the mold is removed in the mold removal step (d) to obtain the surface-attached pad layer 11 with a film.

Next, the forming process of the back pad layer 12 will be described with reference to the explanatory view of FIG. Note that the mold urethane foam mold used for foam molding has the same structure as a general one, and therefore a detailed description thereof will be omitted.
In the material setting step of FIG. 5A, the front pad layer 11 with a film is set in the lower mold 70, and the concave portion 11 a of the front pad layer 11 (specifically, in the concave portion of the back film 13). , A jelly-like urethane stock solution 90 is injected. Next, in the foaming step (b), the foam upper mold 80 is closed in the foam lower mold 70 and the urethane stock solution 90 is foamed to form the back pad layer 12 by integral foam molding, thereby forming the seat main pad 10. Next, the seat main pad 10
After cooling, in the demolding step (c), the mold is opened and then demolded to obtain the seat main pad 10.

It is desirable that the thickness of the back pad layer 12 is in the range of 20% to 80% of the thickness of the seat main pad 10. If it is less than 20%, it becomes difficult to obtain a cushion feeling of the mold pad. Also 80
%, The effect of the surface flexibility inherent in the fiber elastic body is reduced, and the effect of preventing stuffiness is also reduced. The urethane foam of the back pad layer 12 has a density of 0.0
It is used in the range of 35 to 0.06 g / cm ³ . 0.0
The densification of 6 g / cm ³ or more is higher than the cost of conventional general molded urethane foam and is not general.
On the other hand, when the density is reduced to 0.035 g / cm ³ or less, the cushioning property required for urethane foam cannot be exhibited. The hardness of the urethane foam at the time of 25% compression is, for example, 10 to 10.
20 kg / cm ² .

The density of the fibrous elastic material of the surface pad layer 11 is in the range of 0.03 to 0.08 g / cm ³ . If it is 0.08 g / cm ³ or more, it becomes hard, and the cushion feeling as a cushion material is impaired. If it is less than 0.03 g / cm ³ , durability (settling, compression restoring property) is poor, and it deviates from an appropriate range as a sheet material.

According to the seat main pad 10 described above, since the fibrous elastic body forming the front pad layer 11 can be formed with a substantially constant thickness t (see FIG. 2), the variation in density can be reduced. Thus, the time for thermoforming can be shortened. A comparison experiment was conducted between the front pad layer 11 and a conventional product having a full-foam structure of a fibrous elastic body. As a result, the molding time of the front pad layer 11 was about 50% of that of the conventional product. We were able to.

The surface pad layer 1 made of a fibrous elastic body
1 and a back pad layer 12 made of urethane foam, and the weakness of the fibrous elastic body can be compensated for by the flexural characteristics and the hardness characteristics of the urethane foam. Bending characteristics and hardness characteristics can be improved as compared with the structure. FIG. 6 is a numerical table showing comparison characteristics of the molded urethane foam used for the seat main pad, the fiber elastic body, and the seat main pad 10 of the above-described embodiment which is a developed product. In FIG. 6, according to the developed product, the flexural property and the hardness property of the molded urethane foam are different from those of the developed product, as can be seen from the numerical values of 25% compression hardness, the amount of deflection under a load of 50 kg, and the spring constant under a load of 50 kg. It can be seen that it has an intermediate property between that of the material and that of the fiber elastic material.

The present invention is not limited to the above embodiment, but can be modified without departing from the scope of the present invention. For example, the present invention can be applied not only to the seat main pad 10 of the seat cushion but also to a seat main pad of the seat back (also referred to as a seat back pad). Further, in the embodiment, the molded slab urethane foam is employed, but a slab urethane foam may be employed instead. The surface pad layer 11 made of a fibrous elastic body can also be formed by a blowing method (see FIG. 9) instead of the above-described laminating method. Further, as the fiber material of the fibrous elastic body, it is possible to employ a synthetic fiber material such as a polyamide fiber, an acrylic fiber, and a polypropylene fiber in addition to the polyester fiber. Also, the front pad layer 11 and the back pad layer 12 can be bonded with an adhesive or the like after being formed respectively. In addition to the front pad layer 11 and the back pad layer 12,
A three-layer structure in which a back pad layer made of a fibrous elastic body is provided on the back surface of the back pad layer 12 may be considered. In this case, it is also possible to insert the back pad layer 12 into the front pad layer 11 and the rear pad layer and perform simultaneous molding. When the surface hardness of the seat main pad 10 is to be intentionally changed, for example, when the side portions are hard and the lower part of the thigh is soft, the thickness of the fiber elastic body forming the front pad 11 is intentionally adjusted. Can be dealt with.

[0034]

According to the seat main pad of the present invention,
By adopting the composite structure of fiber elastic body and urethane foam, it is possible to reduce the variation in the density of the fiber elastic body and shorten the heat molding time. And the hardness characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a seat main pad.

FIG. 2 is a right sectional view of the same.

FIG. 3 is an explanatory view showing a molding step of a surface pad layer.

FIG. 4 is an explanatory view showing a bonding step of a back film.

FIG. 5 is an explanatory view showing a step of forming a back pad layer.

FIG. 6 is a numerical table showing comparison characteristics of a seat main pad.

FIG. 7 is a partially broken perspective view of a vehicle seat having a spring structure.

FIG. 8 is an explanatory view showing a forming method of a lamination method of a fiber elastic body.

FIG. 9 is an explanatory diagram showing a molding method of a blowing method of a fiber elastic body.

[Explanation of symbols]

 10 seat main pad. 11 Front pad layer 12 Back pad layer

Claims (1)

[Claims] 1. A front pad layer comprising a fibrous elastic body and a back pad layer comprising urethane foam provided on the back side of the front pad layer, wherein the front pad layer has a substantially constant thickness. A seat main pad characterized by being formed.