GB2157163A - Upholstered articles - Google Patents

Abstract

A mattress or like upholstered article has a foamed polyurethane outer layer 10, 12 and a foamed polyurethane intermediate layer 14 which is profiled 16 so that only a part of layer 14 is in contact with layer 10 when the mattress is uncompressed, each layer having been treated to improve the flame retardancy. <IMAGE>

Description

SPECIFICATION Upholstered articles This invention relates to upholstered articles and particularly upholstered bedding such as mattresses and pullows.

As a consequence of the risk of fire it is now thought desirable that mattresses and pillows used in hospitals or homes for geriatrics or the mentally handicapped should have a high degree of flame retardancy, preferably the highest standard given in D.O.E/PSA Fire Standard No. 6 and the material itself giving a Class 1 to British Standard 476 part 1.

Mattresses made of foamed plastics material such as polyurethane foam can be treated to render them sufficientlyflame retardant. However, a polyurethane foam mattress treated in this way becomes stiff and is not sufficiently yielding or comfortable for hospital or geriatric use.

The present invention has been made from a consideration of this problem.

According to the invention there is provided an upholstered article comprising outer layers of foamed polyurethane having therebetween at least one intermediate layer of foamed polyurethane, said intermediate layer being profiled such that when the article is uncompressed only a part of the surface thereof is in contact with one or both adjacent layers, each layer having been treated to improve the flame retardancy.

There may be more than one intermediate profiled layer and each such profiled layer may be profiled on one or both surfaces. The kind of profiling on each layer and each surface may be the same or different. The particular kind of profiling and the extent thereof will depend upon the characteristics required of the product. The greater the amount of profiling introduced into the mattress the softer the mattress will feel in use. A particularly effective profiling comprises an array, preferably a substantially regular array, of peaks and troughs. If profiling of this kind is used on two or more layers it is desirable that the peaks of one layer should be in register with the peaks of the other layer or layers and not in register with the troughs.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure lisa section through one embodiment of a mattress according to the invention; Figure 2 is a section through another embodiment of a mattress.

Figure 3 is a section through a sheet of foam showing how it is profile-cut; Figure 4 is a section through a layer formed from the sheet of Figure 3 used to form the mattress of Figure 2; and Figure 5is a section through a pillow.

Referring to Figure 1 the mattress comprises outer layers 10, 12 of foamed plastics material such as foamed polyurethane having sandwiched therebetween an intermediate layer 14 also of foamed plastics material such as foamed polyurethane. Each of the layers is treated to render it flame retardant. One surface 16 of the intermediate layer is profiled in the form of a plurality of peaks 18 and valleys 20.

In the embodiment of Figure 2 the mattress includes the same layers as in the embodiment of Figure 1 with the inclusion of an additional intermediate layer 22 which is profiled with peaks 18 and valleys 20 on both surfaces thereof. Intermediate layer 22 is formed from two separate layers 24, 26. The layers 24 and 26 are formed by profiled cutting of a sheet of foam 28 as shown in Figure 3 and then bonding the outer faces 30,32 of the foam sheettogetherwith the result as illustrated in Figure 4. The spacing of the peaks and valleys on both surfaces of layer 22 is the same and is also the same as the spacing of the peaks and valleys on the surface 16 of layer 14.Moreover the peaks and valleys on each surface of the layer 22 are in register with the peaks and valleys on the other surface and also in register with the peaks and valleys on the surface 14 of layer 16.

As mentioned above when polyurethane foams are treated to render them flame retardant they become heavier and stiffer and thereby less comfortable. This is illustrated in the following Table 1 comparing treated and untreated polyurethane foams which substantially meet the requirements of British Standard 5223 Part 2:1979, Flexible polyurethane foam mattresses.

TABLE 1 PROPERTY REQUIREMENT VFR* VFR UNTREATED POLYURETHANE FOAM - GRADE BS 5223 3/68 5/80 SP - 14 ** BS 3379 - CLASS S S S S % Hardness Loss - 29.7 27.5 24 % Height Loss - 3.7 8.7 2.1 Final Hardness N - 111 87 Tensile Strength Pa 90 min 106 134 108 Loss in Tensile Strength After (a) humidity ageing % 10 max -8.7 -9.2 -2.7 (b) heat ageing % 10 max 7.6 4.1 -5.0 Elongation at Break % 180 min 217 202 220 Compression Set % 5 max 11.5 13.5 2.8 Hardness Characteristics &commat; 40% Indentation Class - 3 90-120 147/158 179 115 * VFR is a polyurethane foam treated to render it flame retardant manufactured by British Vita PLC. ** SP-14 is the grade name given to polyurethane foam that complies with B.S.5223 manufactured by British Vita PLC.

ADDITIONAL TEST RESULTS Typical Compression S/S Characteristics (Instron-Sample Size 75 x 75 x 25 mm) &commat; 25% Compression 354 482 241 &commat; 40% " 436 599 258 &commat; 50% " 522 733 283 &commat; 65% " 758 1149 375 The properties of mattresses made of untreated polyurethane foam and of profiled and solid flame retardant foams listed in Table 1 are set out in Table 2. TABLE 2 Untreated Polyurethane Treated Polyurethane Foam SP-14 3/68 5/80 (TO BS 5223 Part 2) SOLID PROFILE SOLID PROFILE Apparent Density* KG/M3 28.5 90.1 66.7 94 73.7 Hardness Index N 180 244 139 356 191 S 3379 Pounding (Product) % Hardness Loss 30.5 24.2 32.4 25.8 34.6 % Height Loss 3.6 5.1 10.3 2.6 6.5 Final Hardness 128 185 118.8 264 125 Load/Deflection Curve Hampden 25% (N) 160 195 76 284 152 40% 216 300 172 436 244 65% 384 690 436 OFF SCALE OF M/C TEST SAMPLE DIMENSIONS 15 IN X 15 IN X 5 IN The table shows that the profiled mattress of treated polyurethane foam has similar comfort characteristics to the untreated polyurethane foam made for use in hospitals according to B.S.5223, Part 2, 1979.

The profile cut VFR 3/68 mattress is clearly softer than the untreated polyurethane foam mattress i.e. 139 N compared with 180 N respectively. The solid VFR 3/68 mattress is 244N. The influence of profile cutting is obvious, since the hardness is reduced considerably, in this example, by about 43%, as a direct consequence of profile cutting.

The profile cut VFR 5/80 is almost identical in hardness to the polyurethane foam, i.e. 191 N and 180 N respectively.

The loadldeflection curve for VFR full depth mattresses shows generally a steeper slope for the load deflection curve than the profile cut foamed untreated polyurethane foam mattresses. In other words a patient will sink lower into the mattress and a greater area of the patient's body will be supported by a mattress formed from untreated foam and profile cut foam compared with a mattress formed from full depth VFR polyurethane foam.

Comparing the profile cut foam with untreated polyurethane foam the load deflecion curve of the VFR 5180 matches fairly closely that of the untreated polyurethane foam. The VFR 3168 appears to offer superior comfort at lower indentations, i.e. greater deflection at low loads, and gives increased ability to support a load as the weight increases.

The invention is not confined to mattresses and can be applied to other articles such as pillows. An example of a pillow is shown in Figure 5 and comprises two pads 36 and 36' of uniform thickness each of which is surrounded by a wrapping 38 and 38' of profiled material similar to the profiled material of layer 14 in Figure 1. Each wrapping 38 and 38' is arranged with the profiling directed towards the pad 36 and 36' and is of dimensions so that the ends overlap as indicated at 34 and 34' to form a double thickness. The wrapped pads are placed side by side with the overlapping parts of the wrapping 34 and 34' adjacent each other and are surrounded by an envelope 40 of profiled material also similar to layer 14 in Figure 1 arranged with the profiling directed inwardly.

A pillow constructed as described above with each pad 36 having the dimensions 12.5" x 4.25" x 1", each wrapping 38 having dimensions 34" x 20.5" x 1" (1" profile cut) and the envelope 40 having the dimensions 24.5" x 16.75" x 1" (1" profile cut) was tested and the properties are set out in the following Table Ill.

Property Test Method Result weight GMS 1843 Dimensions Ins. 23.5 x 16 x 6.8 Indentation Hardness N BS4443:P2 M7A 61 Pounding Loss in Hardness % BS4443:P5 37.3 Loss in Height % 12.6 Compression Characteristics N BS4443:P2 (Hampden M/C) 25% 34 40% 78 65% 256

Claims (11)

1. An upholstered article comprising outer layers of foamed polyurethane having therebetween at least one intermediate layer of foamed polyurethane, said intermediate layer being profiled such that when the article is uncompressed only a part of the surface thereof is in contact with one or both adjacent layers, each layer having been treated to improve the flame retardancy.

2. An upholstered article as claimed in Claim 1, wherein a plurality of intermediate profiled layers are provided.

3. An upholstered article as claimed in Claim 1 or Claim 2, wherein the or each profiled layer is profiled on one or both surfaces.

4. An upholstered article as claimed in any preceding claim, wherein the outer layer is internally profiled.

5. An upholstered article as claimed in any preceding claim, wherein the profiling comprises an array of peaks and troughs.

6. An upholstered article as claimed in Claim 5, wherein the array is substantially regular.

7. An upholstered article as claimed in Claim 5, or Claim 6, containing a plurality of profiled layers, wherein at least two of said profiled layers are arranged with the peaks of one layer substantially in register with the peaks of the other layer.

8. An upholstered article as claimed in any preceding claim, containing a pluraliy of profiled layers, wherein the profiling of different layers is different.

9. An upholstered article as claimed in any of Claims 1 to 7 containing a plurality of profiled layers, wherein the profiling of different layers is the same.

10. An upholstered article as claimed in any preceding claim and comprising at least one further unprofiled intermediate layer.

11. An upholstered article substantially as described herein with reference to Figure 1, Figures 2,3 and 4 or Figure 5 of the accompanying drawings.