GB2037155A - A mattress or cushion of foam plastic - Google Patents

Abstract

A mattress comprises an inner core (1) and an outer cover (2) of foamed plastic having a bulk density of about 50 to 80 kg/m<3> and 25 to 45 kg/m<3> respectively. The core (1) consists of two identical core halves (3, 4) facing each other and having recesses (5) forming channels between longitudinally or transversely extending projections (6). An unstretchable, flexible sheet (8) is glued between the two core halves (3, 4). The cover (2) comprises two cover halves (11, 12) extending beyond the edges of the core, the rim areas of the cover halves (11, 12) being curved about the sides of the core halves (3, 4). The cover halves (11, 12) are glued about the core (1) and to each other at their joining end surfaces. <IMAGE>

Description

SPECIFICATION A mattress or cushion of foam plastic The present invention relates to a mattress of foam plastic.

It is known to use cushions or mattresses of foamed plastic, and which consist of a homogeneous foam layer. Such a mattress is either too hard or too soft depending on the foam plastic selected and the bulk density thereof. Furthermore, when a person is lying on such a mattress, the material easily slips aside thus involving a rather unsteady bed. In addition, cushions comprising recesses are known, whereby the recesses extend from the surface towards the center. Such cushions, however, have a still higher tendency to be unsteady.

The object of the invention is to provide a mattress or cushion of foam plastic, which buy a spring effect efficiently support the body at the same time as it adapts itself to the shape of the body and the limbs.

The mattress according to the invention is characterised by an inner core of foamed plastic having a relatively high bulk density and an outer cover of foamed plastic having a relatively low bulk density compared to the material of the core. As a result a more reliable supporting surface than the previously known mattresses of foamed plastic is obtained, since the cover having the lower bulk density and subsequently a relatively higher resilient capacity adapts itself to the shape of the body and the limbs, while the heavy core supports the body and cooperates in stiffening the mattress and thereby reduces the sliding.

By providing the inner core with a bulk density in the range of 50 to 80 kg/m3, preferably about 60 kg/m3, and by providing the outer cover with a bulk density in the range of 25 to 45 kg/m3, preferably about 35 kg/m3, it is ensured that the core efficiently supports the body while the cover easily adapts itself to the shape of the body and the limbs as it is resilient due to the lower bulk density.

It is preferred that the core comprises an upper and a lower core half situated mirror symmetrically relative to each other and comprising recesses forming channels and opposing each other, and that a substantially plane and unstretchable material sheet is glued between and to the top surfaces of the two core halves abutting each other. In this matter column-like and either longitudinal or transverse projections are formed which function in a similar manner as the previously known inserted steel springs. These projections are by means of the plane unstretchable material sheet stiffened in such a mannerthatthe individual column-like projections are stiffened relative to each other and thereby the sliding effect is further reduced.In spite of the fact that such a mattress or cushion efficiently fulfils its supporting function, it may be manufactured in a labour-saving manner since there is no need for inserting for instance particular spirai springs. In addition, the channels provide a better airing than mattresses completely made of foam plastic and thereby a more healthy mattress.

Although the material sheet might be manufactured of an arbitrarily chosen unstretchable material, it is preferred that the material sheet is a flexible, non-woven fabric layer, since such a material possessing a higher tearing capacity may easily be bound to the foam plastic and be manufactured so as to be unstretchable.

According to the invention the outer cover may comprise two cover halves, each half consisting of a foam plastic sheet having a somewhat larger width and length than the core halves, and the rim areas of which are curved about the side surfaces of their respective core half in such a manner that their circumferential surfaces substantially flush with the plane of symmetry of the core halves, whereby the covers in an easy manner may be manufactured without any waste of material.

Furthermore according to the invention the cover halves may be glued to the surfaces of the core halves turning outwards and to the side and end surfaces thereof as well as to each other along the circumferential surfaces of the covers facing each other. In this manner the individual parts of the mattress may in an easy and labour-saving manner be united.

When the height of the projections located between the recesses corresponds substantially to or exceeds about 0.1 time the thickness of the core, it is ensured that each column-like projection through a sufficient height may function as efficient springs. By maintaining a constant width of the projections a simple manufacturing without essential waste of material is furthermore ensured, since the two core halves may be manufactured by cutting a foam sheet along a crenelated line.

By providing the projections with a varying width and by situating the largest width in the area with the heaviest load, it is in a simple and relatively inexpensive manner rendered possible to vary the supporting function or the hardness of the mattress. This varying possibility may also be obtained by providing secondary recesses situated perpendicular to or inclining relative to the recesses of the core halves, and these secondary receseses are shaped in such a manner that the individual projections form square columns of equal or varying length.

Although various plastic foams such as for instance polyether or polyester foam may be used, it has in practice turned out to be most advantageous to use polyurethane foam owing to its softer character and better durability. In this connection it is preferred that the foam material is fire-retardant whereby the usual requirements with respect to fire protection are fulfilled. As a result the mattress may also be used in institutions. Such requirements appear for instance from Bulletin 117, section A published by Bureau of Home Furnishings, State of California, which inter alia is used by an examination of foam for furniture manufactured by Dansk Textilinstitut (The Danish Institute for Textiles).

If the material used for the material sheet is liquid impermeable, it is preferred to provide this layer with a plurality of small perforationsforthe sake of the airing of the mattress.

The cushion or the mattress according to the invention may, of course, be used by covering it with a detachable sheet, but it is usually preferred to cover the entire mattress or cushion according to the invention with a ticking. In hospitals the ticking may optionally be provided with a zip fastener, thus permitting a separate disinfection of the individual parts.

The non-woven material sheet may for instance be "Fibertex" 100 g/m2. In practice this material has proved to prevent a usually "swimming" or "sailing" supporting surface.

A preferred embodiment of the mattress according to the invention will be described below with reference to the accompanying drawing, in which Fig. 1 is a top view of a corner section of a cushion or mattress according to the invention, whereby some parts have been removed, Fig. 2 is a sectional view through the mattress of Fig. 1 along the line a-a, and Fig. 3 illustrates the two core halves of the mattress immediately after the cutting along a crenelated line.

The mattress according to the invention and illustrated in the drawing comprises a core 1 completely surrounded by a cover 2. Both the core and the cover are made of foam plastic, the core being made of a foam plastic having a relatively high bulk density and the cover being made of a foam plastic having a relatively low bulk density compared to the material of the core. Thus it is preferred that the material of the inner core possesses a bulk density in the range of 50 to 80 kg/m3 and preferably about 60 kg/m3, and the material of the outer cover possesses a bulk density in the range of 25 to 45 kg/m3, preferably about 35 kglm3, thereby providing a mattress of a reasonable hardness and with a reasonable supporting capacity.

According to a very simple embodiment the core may comprise a homogeneous foam plastic mass, but this is not a completely satisfactory embodiment. According to the preferred embodiment the core comprises an upper and a lower core half 3 and 4, respectively, which are identical and situated mirror symmetrically relative to each other. These core halves comprise either longitudinal or transverse channel-forming recesses 5. Between the recesses 5, oblong projections 6 are provided, the top surfaces 7 of which oppose each other, whereby the projections 6 form oblong, resilient, springy columns. A material sheet 8 is provided between the two core halves and glued to the top surfaces 7. This material sheet extends continuously from one side surface 9 of the core to the opposite side surface and from one end surface 10 of the core to the opposite end surface.

In orderto neutralize disadvantageous tensions in the material sheet, which is preferably of an unstretchable material, said sheet must be made of a flexible, non-woven fabric layer, e.g. Fibertex 100 glum2. If a nonporous material is used, e.g. a more or less solid plastic sheet, this sheet should for the sake of the free air passage through the mattress be provided with a plurality of perforations.

This unstretchable, flexible material sheet 8 ensures that the projections 6 functioning as spring devices do not slip relative to each other during the load.

The outer cover 2 is glued onto the core, and this cover comprises two cover halves 11, 12. The cover halves consist of a foam plastic sheet being a short distance longer and widerthan the core. The rim areas 13 of the cover halves are curved about the edges of their respective core half 3,4 and downwards along the sides of the core half in question. In this manner each cover half 11, 12 receives its respective core half 3, 4, said cover halves being glued to the surfaces 14 turning outwards of the core halves and to the side and end surfaces 9, 10 as well as to each other along their opposing circumferential surfaces 15.

In order to ensure a free air passage and thereby an efficient airing of the mattress orthe cushion, the adhesive used for all the gluings is sprayed in a finely pulverized form across the surfaces to be glued in such a manner that a free air passage is present through the binder layer and the opposing foam plastic layers and the material sheet surfaces.

In orderto provide the material sheet with a strength sufficient for resisting tension influences said sheet must have a thickness in the range of 0.1 and 1 mm, preferably about 0.4 mm. In order to permit a correct adaption of the cover to the shape of the body, it is in connection with the above bulk densities for the material used preferred to provide the cover with a thickness in the range of 20 mm and 45 mm, preferably about 30 mm. Concerning the bulk density stated above for the material used for the core it is preferred that the total thickness of the core is between 40 mm and 100 mm, in particular preferably about 70 mm. The height of the projections 6 situated between the recesses 5 corresponds substantially to or exceeds 0.1 time the thickness of the core.According to an a embodiment easy to manufacture the width of the projection is constant along the entire length of the core and corresponds to the width of the recesses and exceeds 0.2 times the thickness of the core, preferably corresponding to the thickness of one core half. Such an embodiment ensures that the two core halves 3,4 may be cut along a crenelated line of the very same foam plastic sheet without waste of material beyond the waste resulting from the top surfaces 7 of the outer projections, cf. Fig. 3.

If it is desired to vary the supporting capacity of the mattress across the entire supporting surface in such a mannerthatsaid mattress possesses the highest supporting effect on the spot subjected to the heaviest load, the width of the projections may vary, whereby the width is largest in the area subjected to the heaviest load, thus also providing the recesses 5 with a varying width.

According to an embodiment the mattress may thus be for instance 130 mm thick, each cover half 40 mm thick, whereas each core half is 35 mm thick, and comprise recesses 5 and projections 6 which are 35 mm wide and 20 mm deep and high respectively.

According to an embodiment not illustrated in the drawing, secondary recesses may in addition to the recesses 5 illustrated be provided in the two core halves 3,4 of the core, said secondary recesses inclining relative to said recesses 5 or being situated perpendicular thereto. In this manner the individual projections form a plurality of square columns, which permits an alternative and simple possibility of varying the loading capacity of the core and the weight of the entire mattress. These secondary recesses may for instance be situated at the ends of the mattress.

Claims (13)

1. A mattress or cushion of foam plastic, characterised by an inner core of foamed plastic having a relatively high bulk density and an outer cover of foamed plastic having a relatively low bulk density compared to the material of the core.

2. A mattress as claimed in claim 1, characterised by the material of the inner core having a bulk density in the range of 50 to 80 kg/m3, preferably about 60 kg/m3, and by the material of the outer cover having a bulk density in the range of 25 to 45 kg/m3, preferably about 35 kg/m3.

3. A mattress as claimed in claims 1 and 2, characterised by the core comprising an upper and a lower core half situated mirror symmetrically relative to each other and comprising recesses forming channels and opposing each other, and by a substantially plane and unstretchable material sheet being glued between and to the top surfaces of the two core halves abutting each other.

4. A mattress as claimed in claim 3, characterised by the material sheet being a flexible, non-woven fabric layer.

5. A mattress as claimed in one or more of the preceding claims 1 to 4, characterised in that the outer cover comprises two cover halves, each half consisting of a foam plastic sheet having a somewhat largerwidth and length than the core halves, and the rim areas of which are curved about the side surfaces of their respective core half in such a mannerthat their circumferential surfaces substantially flush with the plane of symmetry of the core halves.

6. A mattress as claimed in one or more of the preceding claims 2 to 5, characterised in that the cover halves are glued to the surfaces of the core halves turning outwards and to the side and end surfaces thereof as well as to each other along the circumferential surfaces of the covers facing each other.

7. A mattress as claimed in one or more of the preceding claims 3 to 6, characterised by the height of the projections located between the recesses corresponding substantially to or exceeding about 0.1 time the thickness of the core.

8. A mattress as claimed in claim 7, characterised by the width of the projections being constant and corresponding to the width of the recesses and exceeding about 0.2 times the thickness of the core and preferably corresponding to the thickness of one core half.

9. A mattress as claimed in claim 7, characterised by the width of the projections varying and being largest in the area with the heaviest load.

10. A mattress as claimed in one or more of the preceding claims, characterised by secondary recesses being provided in the mutuaily opposed surfaces of each core half, said recesses being perpendicular to or inclining relative to the recesses of the core halves in such a manner that each projection forms island-like, square columns.

11. A mattress as claimed in one or more of the receding claims 1 to 10, characterised by the foam plastic employed being soft polyurethane foam, preferably with addition of fire-retardant agents.

12. A mattress as claimed in claims 3 and 4, characterised by the material sheet being an airimpermeable material and provided with a plurality of perforations.

13. A mattress substantially as described above with reference to the accompanying drawing.