JP2001054690A - Cushioning material formed of fiber aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cushioning material excellent in a formed shape around deep grooves, freely settable in the rigidity and flexibility of its surface part according to an application and moreover having an advantage as the cushioning material formed by an aerating method. SOLUTION: This cushioning material K formed with grooves G 3-60 mm in depth by thermoforming a fiber aggregate comprising matrix fiber formed of crimped synthetic short fiber and binder fiber with a lower fusing point than the matrix fiber, dispersedly mixed in the matrix fiber, is formed by integrally jointing a cushioning member B with grooves less than 3 mm in depth and a cushioning member A with through holes and/or grooves 3-60 mm in depth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushion obtained by thermoforming a fiber assembly in which a binder fiber having a melting point lower than that of a short fiber is dispersed and mixed in a matrix composed of short fibers of synthetic short fibers having a crimped form. About materials.

[0002]

2. Description of the Related Art In general, urethane foam has been widely used as a cushion material for a seat having a complicated shape such as an automobile and an aircraft. However, urethane foam is
Since there are problems such as humidity due to poor air permeability and difficulty in recycling, there has been a long-felt need for a molding material that can be used instead.

[0003] In view of such problems, in recent years, as a material for replacing urethane foam, a fiber aggregate (a cotton aggregate) in which binder fibers having a lower melting point than the short fibers are dispersed and mixed in a matrix composed of synthetic short fibers. A cushion material using a lump (hereinafter sometimes referred to as “cotton”) has been attracting attention as a material capable of solving the above-mentioned problems. The cushioning material is formed by filling a cavity of a mold with cotton and thermoforming the same to thermally fuse binder fibers contained in the cotton.

Conventionally, as a method for filling cotton in a molding die, for example, a lump of cotton is temporarily shaped into a certain size,
There has been adopted a method in which temporarily shaped cotton is manually packed or filled into a cavity of a molding die by an automatic machine such as a robot. However, in this method, it is necessary to temporarily form the cotton once, and thereafter, the temporarily formed cotton needs to be packed in a mold, so that an extra step of the provisional shaping is required, so that the cost is increased, and the provisional shaping is performed. There is a problem that a temporary storage space is required for installing the waste cotton.

[0005] In order to solve such a problem, a method of pneumatically transporting cotton as a small lump of cotton to a molding die without temporarily shaping the cotton (hereinafter sometimes referred to as "air blowing method").
However, for example, JP-B-56-29556 and JP-B-62
-29069 and Japanese Patent Publication No. 27727/1990. In this method, non-temporarily shaped cotton was conveyed to a fiber opening machine by a conveyor, and after being made into cotton lumps opened by the fiber opening machine, the cotton lumps opened were generated by a blower. In this method, cotton is filled into a cavity of a mold while being accompanied by a carrier air flow, and is heated and formed into a cushion material.

[0006] However, in this air blowing method, it is indispensable to mold the cotton by pneumatic transportation. For example, in order to fix a skin to be attached to cover the surface of the cushion material, the surface of the cushion material is fixed. If it is necessary to mold a cushion material with a deep groove in
The following problems occur. That is, when the cushion material having the deep groove is to be molded in the mold while having the deep groove shape, a portion corresponding to the deep groove becomes a projection in the mold. However, when trying to fill cotton into the mold cavity having such projections by the air blowing method, unlike the case where cotton is filled by hand lay-up into the mold at the target location, the area around the deep groove of the cushion material is different. It is very difficult to get the shape well. Also,
If a large amount of cotton is forcibly blown into the mold cavity and compressed to improve the moldability around the groove, the surface of the cushion material becomes hard, and a problem arises in that the desired hardness cannot be achieved.

Therefore, in order to form a cushion material having no deep groove, cotton containing a binder liquid is set between the cushion material and the skin covering the cushion material, and the cotton and the cushion material are melted by hot air or the like. Japanese Patent Application Laid-Open No. Hei 3-
JP-A-49829, JP-A-3-100929, JP-A-3-100930, and JP-A-3-1009
No. 31, for example. Indeed, according to this method, it is possible to obtain a cushion material having a desired surface hardness by appropriately selecting the kind and density of the cotton between the cushion material and the covering skin and / or the cushion material. It is possible.

However, in these methods, the step of setting the cotton containing the binder liquid between the skin and the cushion material is very complicated and troublesome. In addition, since it is necessary to heat by setting cotton containing a binder liquid between the skin and the cushioning material, the skin used in these methods must generally be a heat-resistant material with little heat shrinkage. However, there is a problem that the material of the epidermis is restricted.

[0009]

SUMMARY OF THE INVENTION In view of the above problems of the conventional cushioning material, the present invention relates to a method of forming a good shape around a deep groove, and the rigidity of a surface portion thereof is determined by the purpose of use. A cushion material that can be freely set according to the requirements, and further has an advantage as a cushion material formed by an air blowing method. "
Is to provide.

[0010]

According to the present invention, a binder fiber having a lower melting point than a matrix fiber is dispersed and mixed in a matrix fiber composed of short fibers of a synthetic short fiber having a crimped form. Material having a groove with a depth of 3 to 60 mm formed by thermoforming the fiber assembly, the cushion material has a cushion member (B) having a groove with a depth of less than 3 mm, a through hole having a depth of 3 to 60 mm, and And / or a cushion member (A) having a groove, which is integrally joined to the cushion member (A).

In this case, according to the present invention, as described in claim 2, "the cushion member (B) blows and fills the mold cavity with the fiber aggregate accompanying the conveying air flow. Then, it is preferable to use a cushioning material comprising a fiber aggregate characterized by being thermoformed after forming, for example, in order to reduce the molding cost and obtain a cushioning material having excellent quality.

At this time, the cushioning material of the present invention is characterized in that the cushioning members (A) and (B) are heat-sealed, adhesively bonded, stitched, or fastened together as described in claim 3. It is preferable to be constituted by "being integrally joined."

Further, in the present invention, as described in claim 4, the cushion member (A) is a cushion material formed by thermoforming a nonwoven fabric web and / or a laminate thereof. Is preferred. At that time, as a cushioning material of the present invention, as described in claim 5, "a nonwoven fabric web before thermoforming and / or a laminate thereof is used for the cushioning member (A) after thermoforming." After filling the same mold with the cushion member (A),
By forming the cushion member (B) by thermoforming, it is possible to use a cushion material made of a fiber aggregate, wherein the cushion members (A) and (B) are integrally thermoformed. preferable.

In the cushioning material of the present invention described above, one of the cushioning materials (A) and (B) is softer than the other. By providing the property of “a cushion material that is used”, it is possible to provide a more preferable cushion material when used as a seat cushion material.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brief description will be given below of a fiber assembly used for producing the cushioning material of the present invention. First, as the short fibers of the synthetic fibers constituting the matrix of the fiber aggregate, is not particularly limited,
For example, ordinary polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly 1,4-
Dimethylcyclohexane terephthalate, polypivalolactone, or a short fiber composed of a copolymer thereof,
A mixed fiber of these fibers or a composite fiber composed of two or more of the above-mentioned polymer components is preferable. Further, the cross-sectional shape of the short fiber may be any of a circle, a flat shape, an irregular shape, and a hollow shape.

Further, the crimp in this case is preferably an actual crimp, and the actual crimp may be a mechanical method using a crimper or the like, a method using anisotropic cooling during spinning, a side-by-side type or an eccentric sea core. It can be obtained by, for example, a method of heating the type composite fiber.

On the other hand, as the binder fiber, for example,
Short fibers having at least a constituent component such as a polyurethane-based elastomer or a polyester-based elastomer, and the like,
Above all, it is preferable to use eccentric sea-core type or side-by-side type composite fibers in which these elastomers cover more than half of the fiber surface. These binder fibers may be previously dispersed and mixed in the matrix fibers in accordance with the required performance of the molded article.

The above-described embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view schematically illustrating the cushioning material of the present invention. In FIG. 1, K represents a cushion material, and G represents a groove having a depth of 3 to 60 mm. Here, the cushion material K has a depth of 3-6.
A cushion member (A) having a through-hole and / or a groove of 0 mm and a cushion member (B) having a groove of a depth of less than 3 mm are integrally joined and formed. In the following description of the present invention, “a through-hole and / or groove having a depth of 3 to 60 mm” is simply referred to as “deep groove”, and “including a case where a groove is not formed. The groove will be referred to as a "shallow groove." Further, when the cushion material of the present invention is illustrated, the “cushion member (A)” is represented by a symbol “A”, and the “cushion member (B)” is represented by a symbol “B”.

As described above, the cushioning material K of the present invention is a fiber assembly in which binder fibers having a melting point lower than that of the matrix fibers are dispersed and mixed in matrix fibers composed of short fibers of synthetic short fibers having a crimped form. Body (cotton)
It is manufactured by thermoforming F. At this time, the cushion material K
The cushion member (B) constituting a part of the above-described method is obtained by blowing and filling the mold cavity with the above-mentioned fiber aggregate accompanying the carrier air flow, and then using a thermoformed material to shorten the molding time. In addition, it is preferable because the molding cost can be reduced.

Further, as shown in FIG. 1, the cushion member K of the present invention is formed by integrally joining a cushion member (A) having a "deep groove" and a cushion member (B) having a "shallow groove". It has been formed. On the other hand, in the molding of a cushion material by the conventional air blowing method, a cushion material having a “deep groove” as shown in FIG. It is molded at a stretch.

The cushion member (B) is thermoformed by an air blowing method, which will be described below with reference to FIG. Here, FIG.
FIG. 4 is a side sectional view schematically illustrating a structure of a mold for thermoforming the cushion member (B) by an air blowing method.

In FIG. 2, F is a fiber assembly (a lump of cotton packed by pneumatic transportation), 1 is an upper mold (hereinafter, simply referred to as “upper mold”), and 2 is a lower mold ( Less than,
It is simply referred to as “lower mold”. ) And 3 denote side molds (which also serve as outer frames of the molds, and are hereinafter simply referred to as "side molds"). C represents a mold cavity, and the mold cavity C is formed by being surrounded by a mold wall group of an upper mold 1, a lower mold 2, and a side mold 3. Further, reference numeral 4 denotes a cotton F supply port through which the cotton F is supplied into the mold cavity C by a carrier air flow. That is,
The small chunks of cotton F spread by a spreader (not shown) are conveyed to the mold cavity C by a carrier airflow, and are filled in the mold cavity C. At this time, a group of ventilation holes is perforated in the mold wall group consisting of the upper mold 1 and the lower mold 2 (side mold 3 if necessary), and the cotton F is blown into the mold cavity C while accompanying the cotton F. The conveyed flow can be quickly discharged from the group of vents. In addition,
The group of air holes also has a function of flowing heated air or cooling air into the cotton F through the group of air holes when the cotton F is thermoformed into the cushion member (B).

At this time, the upper mold 1 and the lower mold 2 having the air permeability form an inner peripheral surface of a mold wall of the side mold 3 which also serves as an outer frame, as in a known mold. Each of them is configured to be movable up and down while sliding. Therefore, the cushion material K molded in the mold cavity C can be taken out from the space for taking out the molded product formed by moving the upper mold 1 and / or the lower mold 2 upward or downward. Further, regarding the movement of the upper mold 1 and / or the lower mold 2, the cotton F filled in the mold cavity C is compressed by these movements, and the packing density of the cotton F is adjusted to a degree of compression. By doing so, it can be set according to the purpose. FIG. 2 shows a state after the cotton F is compressed by the movement of the upper mold 1 and / or the lower mold 2 after the cotton F is filled into the mold cavity C by the air blowing method. I have.

The fiber assembly (cotton) F, which is filled in the molds 1 to 3 by the air blowing method by the mold having the above structure, is used as a cushion member (B) as follows.
Thermoformed into That is, the cotton (F) that has been opened to a desired state by the opening machine (not shown) is transported by air, supplied from the supply port 4 that opens into the mold cavity C, and Is filled with cotton F. In this case, when a cushion material having a "deep groove" is filled into the mold cavity C by an air blowing method and then thermoformed at a stretch, a serious problem as described in the section of the prior art is caused. Hereinafter, this point will be described in detail with reference to FIGS. 4 and 5 in comparison with the cushioning material of the present invention.

First, as shown in FIG. 4 (a cross-sectional side view schematically illustrating a conventional cushioning material K ′), a cushion material obtained by a conventional technique has a mold cavity C ′ formed by air blowing. Cotton F '
Is rapidly formed in the mold cavity C ′ into the cushion material K ′ having the deep groove G ′. In this case, as shown in FIG. 5 (side sectional view schematically illustrating the structure of a molding die), the conventional cushion material K ′ is used as the cushion material K ′.
A projection 5 is provided on the lower mold 2 'for shaping the deep groove G'.

However, when the projections 5 are provided on the lower mold 2 ', the flow of the carrier air is blocked by the projections 5 and a drift occurs, or a small lump of cotton F' is caught on the projections 5. Therefore, it is very difficult to uniformly fill the mold cavity C 'with the cotton F'. Further, even if the cotton F 'is uniformly filled in the mold cavity C' without being caught by the protrusion 5, the cotton F 'is compressed by the molds 1' to 3 '. In the process of
The projections 5 provided on the lower mold 2 'become obstacles for uniformly compressing the cotton F'. That is, an excessive compression pressure is transmitted to the cotton F 'at the tip of the projection 5, but a sufficient compression pressure is not transmitted at the root of the projection 5. When such a problem occurs, the cotton F 'is not sufficiently compressed at the root portion of the protrusion 5 (the tip portion of the deep groove G'), so that the packing density of the cotton F 'in this portion is insufficient. For this reason, the quality of the cushion material obtained is also inferior.

Therefore, in the present invention, when the cotton filled by the air blowing method is molded into a cushion material having a "deep groove", a unique problem caused by the projection provided on the mold is avoided. For this reason, the cushion member (A) having a “deep groove” which is a problem during molding and the cushion member (B) having a “shallow groove” which is not a problem during molding are formed separately. Then, the cushion members (A) and (B) thus separated and formed are integrally joined by heat fusion, an adhesive, a suture, or a fastening member.

Here, the reason why the above-mentioned separation molding is employed in the present invention is as follows. That is, originally, it is most preferable that the mold itself does not include the projection as in the molds 1 to 3 illustrated in FIG. However, even if it is assumed that projections for forming grooves in the cushion member (B) are provided on the molds 1 to 3, the small projections (protrusion length of 3 mm
If the cushion member (B) is thermoformed with such a mold, the quality of the formed cushion member (B) itself is hardly adversely affected. Therefore, there is no problem if the cushion member (B) is thermoformed by the air blowing method using a mold provided with such small projections or a mold having no projections. On the contrary, the advantages of the low-cost and short-time molding of the air blowing method can be fully exhibited. 4 and 5
As shown in FIG. 1, without integrally molding at a stroke by the air blowing method like the cushion material K ′ having a “deep groove”,
The cushion member (B) that can be formed by the air blowing method like the cushion material K exemplified in (1) above is formed separately from the cushion member (A).

At this time, separation of the cushion material K illustrated in FIG. 1 into the cushion member (A) and the cushion member (B) is performed as follows. First, when filling the mold cavity C with the cotton F by the air blowing method, it is preferable not to include a protrusion protruding into the mold cavity C. Therefore, as illustrated in FIG. 2, it is preferable that the cushion material K be separated into the cushion members (A) and (B) by the cut surface P including the bottom of the “deep groove”. In this manner, as illustrated in FIG. 2, molding by the molds 1 to 3 having no protrusion protruding into the mold cavity C becomes possible.

However, as already mentioned many times,
As long as the small protrusion has a protrusion length of less than 3 mm, the protrusion of such a protrusion in the mold cavity C does not pose a major problem in molding. Therefore, for such a reason, it is not necessary to separate the cushion material K from the cushion members (A) and (B) at the cut surface P including the bottom of the “deep groove”. The separation may be performed at a cut surface above the bottom of the “deep groove” to the extent that the “shallow groove” remains. The cut surface P may be a curved surface, a flat surface, or a combination of these surfaces. What is important is that, in the air blowing method, the cotton F can be smoothly filled into the mold cavity C, and the mold shape can be favorably formed on the cushion material K.

In general, a comparison between a conventional cushioning material which is integrally formed at a stroke from the beginning without separating the cushioning material by an air blowing method and a cushioning material of the present invention which does not rely on such molding is as follows. Forming the cushion member (B) separately from the cushion member (A) as in the case of the cushion material K, and then joining and integrating them has a disadvantage that the molding process becomes complicated. However, on the other hand, when integrally molded at a stretch by the air blowing method, there is a disadvantage that the property distribution of cotton in the thickness direction of the cushion material cannot be changed.

In this regard, in the cushion material K of the present invention, the cushion member (B)
Make the most of the advantages of the air blowing method. As for the cushion member (A), as described in claim 4 of the present invention, the "thickness direction of the cushion material is obtained by forming the nonwoven fabric web and / or a laminate thereof by thermoforming". In which the property distribution of cotton cannot be changed ". Further, when such a cushion material K is used as a cushion material for an automobile seat as an example, the cushion members (A) and (B)
And different vibration damping characteristics can be imparted to each other, and for example, riding comfort such as a feeling of bottoming can be improved.

In this case, the cushion members (A) and (B)
In order to change the properties of the cushion members (A) and (B), the types of the matrix fibers and / or binder fibers, the mixing ratio, the application of the functional agent, and the packing density of the fibers are changed. This operation becomes very easy. Here, examples of the functional agent include a known insect repellent that suppresses the propagation of mites, a known fungicide that prevents the occurrence of mold, and a known deodorant that deodorizes odors such as tobacco. And the like. Further, as described in claim 6 of the present invention, the cushion member (A)
By making one of (B) and (B) softer than the other, the characteristics of the cushion material can be changed.

As for the cushion member (A),
The properties can also be changed by laminating nonwoven fabric webs composed of the same or different fiber aggregates in the thickness direction or, in some cases, in the direction perpendicular thereto. At that time, the molding conditions such as the number of laminated nonwoven fabric webs and the laminating direction may be appropriately selected depending on the cushion material K to be molded.

At this time, the molding of the cushioning material of the present invention can be performed by a molding method schematically illustrated in FIG. 3 (a schematic side sectional view is shown). In addition, by adopting such a molding method, the mold shape can be accurately formed on the cushion member (A), and at the same time, the cushion member (B) is heat-sealed integrally with the cushion member (B) in the mold cavity C. Can be joined. The mold shown in FIG. 3 includes a male mold 7 and a female mold 8, and a protrusion 5 is provided at the bottom of the female mold 8. Hereinafter, a method of forming a cushion material using the forming die illustrated in FIG. 3 will be described.

Here, in the molding die of FIG. 3 configured as described above, the nonwoven fabric web and / or its laminate (A ′) is formed by a female as shown in FIG. The cushion member (B) which has been placed on the bottom of the mold 8 and already thermoformed by the air blowing method is placed on the top. After the cushion member (B) is placed on the nonwoven fabric web and / or the laminate (A ') in this way, the male mold 7 is moved into the female mold 8 at a predetermined position (FIG. 3- (b)). Position). Then, by performing thermoforming in a mold while maintaining this state, the nonwoven fabric web and / or the laminate (A ′) thereof is converted into the cushion member (A). The nonwoven web and / or its laminate (A ')
The cushion member (A) and the cushion member (B) are integrally bonded to each other by heat fusion with an adhesive derived from the binder fiber of the cushion member (B).

It is not necessary to start such a molding from the case where the cushion member (A) is in the state of the nonwoven fabric web and / or its laminate (A '). That is, similarly to the cushion member (B), the cushion member (A) is also separately thermoformed in advance, and these cushion members (A) and (B) are filled in the female mold 8 in an overlapping manner, and the male mold is formed. While applying a constant load to these cushion members (A) and (B) by 7, heat may be applied to perform thermal fusion. In such a case, since the “deep groove” is already formed in the cushion member (A), the projection 5 shown in FIG.

The bonding between the cushion members (A) and (B) may be performed not only by the thermal fusion performed by such a method but also by an adhesive (adhesive), a stitch, or a fastening member. In the case of using an adhesive (adhesive), a solvent-based adhesive, a resin-based adhesive, a rubber-based adhesive, or the like is applied and / or impregnated in advance to the interface between the cushion members (A) and (B). Can be done. Further, instead of such chemical bonding, the cushion members (A) and (B) may be sewn together or mechanically bonded with a fastening member such as a clip, a clamp or a hook. good.

[0040]

As described above, according to the present invention,
When fabricating a cushioning material consisting of a fiber aggregate having a deep groove having a depth of 3 to 60 mm on the surface, while adopting a method of packing cotton into a molding die by an air blowing method, the method has a disadvantage. Can be overcome. That is,
Substantially, the cushioning material is divided into a portion above the groove and a portion below the groove, and then, a portion above the groove and a portion below the groove are attached to form the cushioning material around the deep groove. The effect is that the cushioning material can be formed, and the hardness of the surface portion can be freely set.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically illustrating a cushioning material of the present invention.

FIG. 2 is a side sectional view schematically illustrating a molding die for molding the cushion member (B) illustrated in FIG. 1 by an air blowing method.

3 shows cushion members (A) and (B) illustrated in FIG. 1;
FIG. 4 is a side cross-sectional view schematically illustrating a method of thermally bonding and joining them together.

FIG. 4 is a side sectional view schematically illustrating a conventional cushion material.

FIG. 5 is a side sectional view schematically illustrating a molding die for molding the conventional cushion material illustrated in FIG. 4 by an air blowing method.

[Explanation of symbols]

 K cushion material A cushion member (A) B cushion member (B) G groove

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29C 65/62 B29C 65/62 D04H 1/54 D04H 1/54 A B29L 9:00 31:58 (72) Inventor Masanao Yamaguchi 3-4-1, Amihara, Ibaraki-shi, Osaka Teijin Limited Osaka Research Center (72) Inventor Takayasu Mori 25, Kamifujiike, Yoshiwara-cho, Toyota-shi, Aichi Prefecture Arako Co., Ltd. (72) Inventor Keisuke Nakagawa 25, Kamifujiike, Yoshiwara-cho, Toyota-shi, Aichi F-term in Araco Co., Ltd. (Reference) 3B096 AA01 AD04 BA01 4F100 AK01A AK01B AK42 AL09 AR00A AR00B BA02 DB14A DB14B DG03A DG03B DG15A DG15B DG20A10B00B30A10B00A10B10B10A10B00 AG26 AH26 MA10 MB01 MB22 MC03 MG04 MG11 MK08 MK15 MW01 4F211 AD16 AG03 AG26 AH26 TA01 TA03 TA06 TC01 TD11 TN01 TN43 TN80 TN87 4L047 AA21 AA 27 AB02 BA05 BA09 BB06 BB09 CB08 CC07 CC09

Claims (6)

[Claims] 1. A thermo-formed fiber assembly in which a binder fiber having a melting point lower than that of a matrix fiber is dispersed and mixed in a matrix fiber composed of short fibers of a synthetic short fiber having a crimped form, and has a depth of 3 to 60 mm. In the cushion material having a groove of (3), the cushion material (B) having a groove having a depth of less than 3 mm and the cushion member (A) having a through hole and / or a groove having a depth of 3 to 60 mm are integrally formed. A cushion material comprising a fiber aggregate, which is formed by being joined. 2. The cushion material according to claim 1, wherein
A cushion material comprising a fiber assembly, wherein the cushion member (B) is thermoformed after being blown and filled into a mold cavity while the fiber assembly is accompanied by a carrier air flow. 3. The cushion material according to claim 1, wherein the cushion members (A) and (B) are integrally joined by a heat-sealing, adhesive, stitching, or fastening member. A cushioning material comprising a fiber assembly. 4. The fiber assembly according to claim 1, wherein the cushion member (A) is formed by thermoforming a nonwoven web and / or a laminate thereof. Cushion material consisting of. 5. The cushion material according to claim 4,
The cushion member (A) after thermoforming is filled with the nonwoven fabric web and / or laminate thereof before thermoforming together with the cushion member (A) in the same mold, and then thermoformed to form the cushion member. (B) A cushion material comprising a fiber aggregate, wherein the cushion members (A) and (B) are integrally thermoformed. 6. The cushion material according to claim 1, wherein one of said cushion materials (A) and (B) is softer than the other. Cushion material consisting of a fiber assembly.