Method for Producing an Elastic Body With Protective Layer

The present invention relates to an elastic body which on its outer surface is entirely or partially provided with a protective layer. The body is generally made of a plastic which has been allowed to foam or expand. The body is thus composed of a number of cells, each enclosing a volume. Said cells are punctured to allow air to flow in and out through the cells. Puncturing of the cells is obtained by heat-treating the body. Such a body is provided entirely or partially with a film which is either placed over the body or secured through the body in one way or another. Adhesive or other known methods can be used to effect the attachment. One method is to heat the outer surface of the body so that it becomes tacky and the film applied thereon adheres to it. The purpose of the film is not to allow moisture through and it should also be of a type which will allow substances, bacteria and other particles which may adhere to the protective layer, to be easily removed with the help of a suitable cleaning agent. In certain cases treatment in an autoclave may even be advisable. Many applications are feasible for a body such as that described above which is coated with a protective layer. One application is as a bed mattress, in which case the body is generally parallel-epipedic in shape. The upper and lower surfaces and the longitudinal side surfaces of the mattress are coated with said protective layer. The transverse side surface, however, have no protective layer. This is to permit the passage of air to the cells in the mattress. The coated surfaces of such a parallel-epipedic body are generally somewhat rough and the layer applied is therefore not flat. This allows air to circulate between the upper surface and the user of the mattress. The movements of the user of such a mattress cause a creaking noise which is disturbing if the user is not alone.

The object of the present invention is to eliminate the above-mentioned disturbing sounds. This is achieved by placing a fabric layer between the body and said protective layer. The fabric may be attached both to the protective layer and to the body itself.

A suitable material for the fabric is nylon charmeuse. This may have a weight of 63 gram/m.sup.2.

A suitable material for the mattress body itself is polyether. If polyether is used this should have a weight of 30 kg/m.sup.3. Highly elastic cold foam consisting of cold-foamed polyether may also be used. Its weight should be 37 kg per m.sup.3.

The present invention will be described more fully with reference to the accompanying two drawings in which the figures show a mattress in perspective at various stages of manufacture.

FIG. 1 shows a mattress core between fabric layers.

FIG. 2 shows fabric layers covering the longitudinal sides of the core and attached or about to be attached thereto by a longitudinal strip disposed between the same.

FIGS. 3 and 4 show outer plastic layers placed over the fabric layers.

FIG. 5 shows the integrated elastic body of the invention.

In the drawings 1 is a mattress consisting of a parallel-epipedic core 15 of a plastic which has been allowed to expand to form a foam consisting of a number of cells, each enclosing a space. The cells have been penetrated by means of heat-treatment during production so that air can pass through them. A suitable material for the core is a material as above, which is also described in Table I.

The mattress core has an upper part 2 and a lower part 3, two longitudinal sides 6 and 7 and two short sides 4 and 5. Two fabric halves are placed over the upper part 2, lower part 3 and longitudinal sides 6 and 7 so that said surfaces are completely covered by the two fabric halves. The opposite edges of the two fabric halves meet along the longitudinal sides 6 and 7. The fabric is preferably nylon charmeuse but other types of fabric may of course be used. Nylon charmeuse is described in Table II.

The fabric may be secured to the mattress core, the latter having been heated to provide a tacky surface. The pieces of fabric covering the longitudinal sides 6 and 7 may be attached thereto by strips provided with attachment means on both sides. One such strip is shown in the drawings on the longitudinal side 6. This strip is designated 8 as shown in FIG. 2. The strip on the longitudinal side 7 is identical to the strip 8. A protective layer consisting of two halves 12 and 13 is placed over the fabric layers 9 and 10. The layers 12 and 13 consist of a plastic which is non-permeable and have a surface allowing bacteria, substances and other undesirable particles to be easily removed and which will also stand treatment in an autoclave. The plastic can be secured to the fabric-covered core by heating the core, whereupon the surface becomes tacky and this tackiness can penetrate through the fabric. Should this not be so, an adhesive or a foil provided on both sides with adhesive is applied between the fabric and the protective layer. The edges of the parts 12 and 13 of the protective layer are substantially in contact with each other along the longitudinal sides 6 and 7. Said parts can be caused to adhere by heating the mattress core or by using an attachment strip coated on both sides with adhesive and arranged between the fabric layers 9 and 10 and the protective layers 12 and 13. In the drawings such an attachment strip is only visible on the longitudinal side 6 where it is designated 11. The two joints formed by the parts 12 and 13 of the protective layer on the longitudinal sides 6 and 7 are covered by a covering strip, denoted 14 on the longitudinal side 6 as shown in FIG. 3. A suitable plastic for the protective layer is highly elastic polymer film. The plastic is described in Table III.

The mattress core described above is thus surrounded by a fabric layer and a protective layer on four sides, two sides remaining uncovered, i.e. the short sides 4 and 5. Said sides are left uncovered in order to allow air to flow freely in and out of the mattress to retain its elasticity.

One application for the invention has been described above, that of a mattress. However, it should be obvious that the invention can also be used for cushions, pillows, car-seats, back-rests in furniture and for other applications where it is desired to avoid the sound effects mentioned above.