GB2199739A

GB2199739A - Cushion

Info

Publication number: GB2199739A
Application number: GB08724459A
Authority: GB
Inventors: Nobuhisa Fuchigami; Kazushige Ebe
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 1986-12-01
Filing date: 1987-10-19
Publication date: 1988-07-20
Anticipated expiration: 2007-10-19
Also published as: DE3740743A1; JPS63139509A; JPH07106167B2; GB2199739B; GB8724459D0

Description

2199739 CUSHIONING STUFF AND MANUFACTURING METHOD OF THE SAME The

present.invention relates to a cushioning stuff suitable for a packing of a seat such as a seat of a vehicle, household or business chair, sofa and the like, and especially to a cushioning stuff having different physical properties with portion(s) and excellent in an ability to support a sitting po-sture of human body.

A conventional cushioning stuff is mainly composed of polyurethane foam or foamed rubber as its material, and usually prepared by foaming the material in a mold or by cutting a larger size foamed material into a desired shape.

In this case, the cushioning stuff has a defect that it cannot cope with the need to vary the rigidity of it with portion(s) in order to support a sitting posture firmly, since the material is homogeneous with uniform physical properties.

To make up such a defect, a method is p--Oposed in which an other kind cushioning material having a desired rigidity is held at desired portions) beforehand and polyurethane foam is foamed in its neighborhood to form a composite cLshioning stuff.

However, this kind of cushioning stuff can not be recognized as a preferable one, because a resinified boundary layer of the polyurethane foam is, formed on the surface with which the other kind cushioning material contacts, and the resinified boundary layer is so poor in the cushioning property U 2.

as to cause an incongruous feeling against the cushioning stuf..,c.

L.

Besides, it tends to cause insufficient adhesion with the other kind cushioning material at the contact area, and the productivity of such a composite cushioning stuff is not good.

Recently, a new structure of seat for vehicles has been developed to support a sitting posture firmly.

Fig.1 shows an oblique view of an example of such a seat. A backsupporting portion 1 of a reclining part A and a sitting portion 2 of a seating part B are fabricated in shapes to enable a sitting person to fit comfortably in the parts. Piled Do.rtions 3, 3 are provided or, both sides of the back-supporti.,,,g portion 1 to hold the upper bo,-y of a sitting person, and piled portions 4, 4 are provided on toth sides of the sitting portion 2 zo hold the waist of the sitting person.

The piled portions 1-, '-') of the back-supporting pa7t and 'L'-e piled portions 4, 4 of --he seating part B are importan4L. portions to support the sitting posture. Needless to say, it is if a car driver can support his driving postur.e and his body to sideslip ca--z--rg a drift of his eye position or, an occasion of cornering.

Therefore, for the P=-DOse of supporting the sittitg -ost,L:--e firmly, the piled porl-',-,,s 3, 3 and 4, 4 are usual---/ -abr-icated from materials havi:-.g a higher rigidity than thcse -jsed for the backsupporting po-rtion 1 and the sitting portion, 2.

However, when marked differences in softness and it cushioning feeling are noticed '.-,o-'Lween those for the backsuppo.-.?tiig portion 1 and the p----ed portions 4, 4, and between --he z i ii C) 41 3.

sitting portion 2 and the piled portions 3, 3, the difference induces an incongruous feeling to the sitting person to make the seat uncomfortable.

Accordingly, there is a need for a cushioning stuff for a seat which gives no difference in feeling between the backsupporting portion 1 and the piled portions 3, 3 and between the sitting portion 2 and the piled portions 4, 4, but performs different functions at these portions.

A seat prepared by packing the aforementioned conventional composite cushioning stuff will be explained using Fig.3, which is the crosssectional view of the back-reclining part A of Fig.1 on line A-A". - A pair of back-supporting side blocks 5 having a piled portion:)' for performing the bodysupporting function and composed of a comparatively rigid foamed material are arranged on both sides of the back-supporting portion 1 composed of a comparatively soft foamed material 11.

In this case, as the back-supporting side blocks 5, 5 are composed of a comparatively rigid foamed material with low tensile strength, deformation resulting from repeated sitting tends to generate crack(s) at groove portions 7, 7 to result breaking of the seat.

Further, as the boundarY 51 between the back-supporting portion 1 and the back-supporting side block 5 is a contact area of different materials having different rigidity, adhesion at the area is apt to be insufficient and separation of materials at the area usually occurs.

The cross-section of the seating part B on line B'-B" 4.

has a similar structure with that shown in Fig.3, and problems between the seat side block having the piled portion 4 and the sitting portion 2 are the same with the above.

Especially in the back-reclining part A, both of the back-supporting portion 1 and the piled portions 3, 3 are recuested to have cushioning properties. The back-supporting portion 1 is allowable if comfortable cushioning feeling is given for an upper body leaned against it. But the piled portions 3, 3 arze expected to be a supporting means for preventing a body from swaying sideways as well as to be a cushion, therefore cushioning prc--erties in accordance with respective purposes are necessary. Ho-,..-n-ver, the complex cushioning stuff having the structure of Fig.3 is not preferable because it possesses marked difference in feeling between the back-supporting portion 1 and the piled pc--t-Jon 3, 3.

Japanese Patent Provisional Publication No. 96195/1980 (Tokkai Sho 55-96195) discloses a multilayer foamed product corriprising a layer of rigid pol--\--j--?et-ane foam and a layer of soft polyurethane foam which are bounc together along the boundary of th=- rigid and soft layers:-:b,-,,ploying an adhesive.

However, the product is composed of mere plane lamination of different cushioning materials, and does riot show a remarkable effect of supporting a sitting posture of a driver.

The object of the present invention is to provide a cushioning stuff suitable to be --sed as packing of a seat which gives no uncomfortable feelling, exhibits marked effect of 1 5.

supporting a sitting posture, and predominant in the strength and productivity.

The present invention accomplished the object by a cushioning stuff comprising a first foamed material and a second foamed material having different physical properties from that of the first foamed material, and the second foamed material is enclosed and incorporated with the first foamed material by simultaneous foaming of the first and the second foamed materials in a mold.

FJg.1 is an oblique.view off a seat for vehicles for which a cushioning stuff of the present invention is applicable; Fig.2 is a c-ross-sectional view Of thC scat in Fig.1 on line A' showing structure of a cushioning stuff of the present invention; Fig.3 is a cross-sectional view of the seat in Fig.1 on line A'-A" or B'-B" showing the -----ructure of a convent ioiir-.- cushioning Stuff for seats; and Fig.4 - Fig.7 show processes for manufactur--,:-g the cushioning stuff having the structure shown in Fig. 2.

The cushioning stuff of the present invention is composed of a first foamed material and a second foamed material,'rom that of the first having diff-Perent physical properties foamed material, and the second foa=ed material is enclosed and incorporated with the first foamed material by simultaneous foaming of zn-- first and the second foamed materials in a mold. 'his case, usually the first foamed mate 11 - rial is a 6.

comparatively soft foamed material and the second foamed material is a comparatively rigid foamed material.

The present invention will be explained using Fig.2 which shows a crosssectional structure on line A'-A" of the back-reclining part A of a seat for vehicles exemplified in Fig.l.

A first comparatively soft foamed material 11 forms a unified block composing a back-supporting portion 1 and piled portions 3, 3 and a second comparatively rigid foamed material 12 is positioned at the core of piled portion 3 enclosed and incorporated with the first comparatively soft foamed material 11 by simultaneous foaming of the first and the second foamed materials in a mold.

This means that the second foamed material 12 is buried in the first foamed material 11 and does not appear at the surface of the first foamed material. However, as far as it does not obstrcut the function of the present invention, the appearance of a small part of t,-,e second foamed material at the surface of the first foamed material is allowable and belongs within the scope of the present invention.

The cross-sectional structure of the seating part B on line B'-B" exemplified in Fig.! is similar to that of the backreclining part A shown in Fig.2.

In the cushioning stuff having the cross-sectional structure as shown in Fig.2, the comparatively rigid foamed material 12 (corresponding tO 'Lhe material composing block 5 in Fig.3, which gave incongruous feeling to a sitting person) is c 1 1 ip 1 C) enclosed by the comparatively soft foamed material 11 which is suitable for sitting, and no resinified boundary layer of the foamed materials are formed as the result of simultarieousfoaming of the first and the second foamed materials in a mold.

Therefore, the cushioning stuff gives no incongruous feeling to a sitting person, but has an excellent property that the back-SUDPorting portion 1 shows comfortable cushioning ability and the piled portion 3, 3 perform good body-supporting function.

In the conventional composite cushioning stuff sho-vin in Fig.3, there exists the problem of the inferior adhesion to result the separation of connection at the boundary 5' betweer, the back- suppo rt Ing portion I and the bac k- support ing side b! ock as described above. However, in the cushioning Stuff-of the present invention shown in Fig.2, the boundary between the first, foamed material. 1-1 and the second foamed material 12 does rjo, cause the proble.-ji of separation, since the second foamed mater-ja--, in -he first foamed material arid both materials 12 is burie are foamed in a mold, 1he comparatively rigid foamed material used for purpose of body- supporting is rather expensive, but applicatiDai of the Pxpensiye- rigid foamed material can be limited to onLy necessary portions in the present invention, so the volume required for the rigid foamed material is smaller than conventional composite cushioning stuff sho,,-,-n in Fig-3, which will lead to a reduced material cost of the cushioriirig stuff the present inVellti0n.

1 f 8.

0 ha%,i, Process for manufacturing the cushioning stuff g the structure as shown in Fig.2, in which at predetermined portion(s) in the first comparatively soft foamed material, the second comparatively soft foamed material is enclosed and incorporated with the first comparatively rigid foamed material will be explained in detail using Fig. 4 - Fig.7. In Fig.4 Fig-7, symbol 20 denotes a mold for foaming and molding of the materials.

- AS shown in Fig.4, a raw material 21 to form a Comparatively soft polyurethane foamed material is mixed under high speed agitation in a mixing-head (not shown), and charg;-=,-' through a nozzle 10 into inner space 23 and 24 of a mold 20 corresponding respectively to the piled portion and the backsupporting portion.

T'-en, as shown in Fig.5, after the first raw 7,,ater.-la"-t in the mold proceeded foaming to ti-e extent of around -;0-60,-c c-" the final foam volume (a foam volume at the completion of foami,,-.g), a raw material 22 to for- a comparatively rigid poly,:--et"-a:e foamed material is mixed under high speed agita----'or, in a -ixi.,-g-liead (not shown), and c,arged through a nozzle -'C' into -.he inner space 23 of the mold where the raw material 21 to form -.-e comparatively soft pol-ure:,-lane foamed material was already cha:,ged.

Since the first raw material 21 is in a stage of a-c-and 20-60/% foamming and low density, the second raw material 22 charged afterward sinks into the foaming raw material 21.

',.z another way, as shown JIn Fig.6, after the raw 1 4 1 9.

0 material 21 proceeded foaming to the extent of around 20-60% of the final foam volume, the second raw material 22 is charged through the nozzle 10' on an inclined inside surface 23' of inner space 23 of the mold. The charged raw material 22 sinks into the already charged raw material 21 through the inclined surface.

In any case as shown in Fig.7, under a state that the raw material 22 to form the comparatively rigid polyurethane foamed material being charged afterward is enclosed by the already charged raw material 21 to form the comparatively soft polyurethane foamed material, both raw materials proceed foaming simultaneously with respective creaming time and rise time in accordance with their compositions and conditions to fill inner space of the mold 20, and a cushioning stuff having the structure shown in Fig.2 is obtained.

Compositions of raw materials to form a comparatively soft and rigid polyurethane foamed materials are shown in Table 1, and a manufacturing method including the timing for charging the raw material to form the comparatively rigid polyurethane foamed material after the raw material to form the comparatively soft polyurethane foamed material was charged will be explained hereunder, however, the embodiment never res trict the scope of the present invention.

In order to obtain the state as shown in Fig.7, in which the raw'material 22 to form the comparatively rigid polyurethane foamed material is enclosed by the raw material 21 to form the comparatively soft polyurethane foamed material by charging differently formulated raw materials as shown in Table 1 1 0 10. into the same space, it is important to carry out charging of the raw material to be charged afterward (the second raw material to form the comparatively rigid foamed material) at their precreaming stage into the already charged raw material (The first raw material to form the comparatively soft foamed raw material) when the latter proceeded foaming to the extent of around 20-60% of the final foam volume (composition of Table 1 proceeds foaming to 30% after 6 seconds from the beginning of initial raw material charge).

The timing of the second raw material charge and the force of sinking (speed and the like) of the charged second raw material into the foaming first raw material are important and to be decided by experiment.

When the raw material to be charged afterward is charged too early or with too much sinking force, the raw material charged afterward passes through the layer of the raw material charged previously and forms an underlayer, and the two raw materials are settled in two layers of upper and lower layers, as disclosed in Japanese Patent Provisional Publication No. 96195/1980, and the raw material charged afterward are not in the state of being enclosed by the previously charged raw material.

Further, when the raw material to be charged afterward is charged too late or with too weak sinking force, or the raw material to be charged afterward proceeded beyond the creaming stage to reach the rise stage when charged, the raw material charged afterward can not sink into the layer of the raw material 4, charged prev iously and remains as an upper layer, thus the two raw material also are settled in two layers of upper and lower layers.

Table 1

Raw material formulated (wt%) Polyether V4702(Dow Chemical Co.) POP991O(Asahi Glass Co.) Diethanol amine Amine Catalyst DABCO 33LV(Sankyo Airproducts Co.) NMM(Kao Co.) Silicone SM74C(Toray Co.) H 2 0 Diisocyanate TDI 80(Nippon Polyurethane Co.

C-MDI(Nippori Polyurethane Co.) Comparatively Comparatively soft foam Rigid foam 0.7 0.5 - 0.5 2.5 36 40. 1 12 36 0.6 0.5 0.5 2.7 Physical Property Hardness (Kg/20mmO) 16 30 Specific Density (9/cm 3 0.053 o.o6o Elongation W 130 go Tensile Strength (Kg/cm 2 1.3 1.2 Compressive Permanent Set W 6 8 12.

The timing of charge at which the raw material charged afterward can break the surface tension of the previously charged raw material in its stage of "rise", penetrate to reach the predetermined portion without passing through the previously charged raw material layer, and enclosed by the previously charged raw material is important.

The raw material to be charged beforehand is recommended to have the creaming time of around 6 seconds and the rise time of around 80-100 seconds as normally adopted, and the raw material to be charged afterward is recommended to have the composition with longer creaming time of around 8-10 seconds so as to penetrate into the previously charged raw material in a low viscosity state arid shorter rise time of around 60-70 seconds so as to be cured before passing through the layer of previously charged raw material and enclosed by it.

The cushioning stuff of the present invention is an incorporated cushioning stuff having different physical properties by portions in accordance with the requested cushioning functions, giving no incongruous feeling at boundaries between different portions, being excellent in the productivity and possesses great value for applications.

When the cushioning stuff of the present invention is used as packing of seats for vehicles as shown in Fig.1, as the comparatively rigid foamed material in the piled side portions necessary for supporting human body on the seat is enclosed by the comparatively soft foamed material having superior cushioning property, it gives no incongruous feeling when sat or) it and I 13.

v 1 it 19 U shows excellent effect of the body-supporting function with superior strength.

When compared with conventional cushioning stuffs, the rgsc.nt.invention brings about such merits as: a) although two cushioning materials having different rigidity and cushioning properties are incorporated, no incongruous feeling exists when sat on it and recognized as comfortable cushioning stuff; b) incongruous feeling of two different foamed materials at the boundary and anxiety for separation or break due to inferior adhesion do not appear; c) need not to worry about deformation, since it has a structure that the rigid foamed material being weak in elongation and strength and apt to be deformed by sitting load is enclosed by the comparatively soft cushioning stuff; and d) cheap, since the expensive raw material to form the comparatively rigid foamed material necessary for body-supporting is used only for indispensable portion(s).

14.

k 1

Claims

1. A cushioning stuff comprising a first foamed material and a second foamed material having different physical properties from that of the first foamed material, and the second foamed material is enclosed and incorporated with the first foamed material by simultaneous foaming of the first and the second foamed materials in a mold.

2. A cushioning stuff according to claim 1, wherein the first foamed material is a comparatively soft foamed material and the second foamed material is a comparatively rigid foamed material.

A cushioning stuff according to claim 1, wherein both the first foamed material and the second foamed material are polyurethane foam.

4. A manufacturing method of a cushioning stuff comprising; charging a first raw material to form a first foamed material into a mold, foaming the first raw material to the extent of 20 - 60 % volume of the final foam volume, then charge a second raw material to form a second foamed material having different physical properties from the first foamed material into predetermined inner portion(s) of the first foamed material and foaming them simultaneously.

5. A manufacturing method of a cushioning stuff according to claim 4, wherein the first foamed material is a comparatively soft foamed material and the second foamed material is a comparatively rigid foamed material.

6. A manufacturing method of a cushioning stuff according to claim 4, wherein both the first foamed material and 15.

14,1 the second_foamed material are polyurethane foam.

7. A manufacturing method of a cushioning stuff according to claim 6, wherein the raw material to form the second polyurethane foam has longer creaming time and shorter.rise time than the raw material to form the first polyurethane foam.

Published 1988 at The Pwen, OMce. State House. 6571 Righ, Holborn. Londor. WCIR 4TF- Further copies May be obt,"ne'd from The Patent 0-1ce. SmUes Branch. St Mary Cray, Orpington, Kent BRS 3RD Printed by Mu3taplex techniques ltd, St Mary Cray. Kent Con. 1187.