WO2013126972A2

WO2013126972A2 - A material and a method for manufacturing such a material

Info

Publication number: WO2013126972A2
Application number: PCT/BE2013/000010
Authority: WO
Inventors: Willy Poppe
Original assignee: Imhold, Naamloze Vennootschap
Priority date: 2012-02-29
Filing date: 2013-02-26
Publication date: 2013-09-06
Also published as: WO2013126972A3; BE1020548A3

Abstract

Multi-layered material (1) that at least comprises a first layer (2) and a second layer (3) bonded thereto, whereby both layers (2,3) are made from flexible foam and the first layer (2) is made from a foam with a greater permeability to air than the foam of the second layer (3), and whereby the second layer (3) has openings (8) that run across the entire thickness of the second layer (3) in order to enable air exchange between the first layer and the second layer.

Description

A material and a method for manufacturing such a material.

The present invention relates to a multi-layered material and a method for manufacturing such a multi-layered material.

More specifically it is a multi-layered material that is both soft and flexible, but which also provides support, so that it can be used in mattresses, pillows, cushions and similar articles, for example.

Materials for use in mattresses, pillows and similar must satisfy a large number of requirements. For example, such a material must have the right compressibility characteristics to provide the right combination of softness and support, but moisture management is also important in such applications.

Indeed, during use the mattress or pillow absorbs moisture from perspiration. This moisture must be quickly removed from the contact surface with the body of the user in order to prevent a clammy or damp, and thus uncomfortable, feeling .

This moisture also has to be emitted back to the environment, in order to prevent saturation of the mattress or the pillow. In particular this could for example result in the moisture absorption by the mattress and the pillow stopping, and mould and bacterial growth in the pillow or mattress being fostered. The extent to which moisture can be removed from the surface, and the extent to which the moisture can be emitted back to the environment, are highly related to the permeability to air of the material, which in turn is highly related to the extent to which the pores in the material are open, the size of these pores and the total porosity. A known material for the said applications is polyurethane foam, i.e. PU foam, whereby specific elastic properties of the PU foam can be obtained through variations during production, such that it is suitable as a material for the said applications, and is thereby acceptable, both with regard to compressibility and with regard to permeability to air, but does no excel in either of the two areas.

In order to be able to adapt the compressibility and thus the support that a layer of foam material provides, it is known to adhere layers of foam with different properties together in order to reach a compromise. In order to be able to better adapt the compressibility to the requirements, it is also known to give the layers of foam different thicknesses over the surface so that the compressibility is location-dependent and to make such a composite layer corrugated in two directions.

This is published in DE 200.17.581, whereby only the mechanical properties of the separate foam materials play a role in the selection thereof. Another known material for the said applications is viscoelastic foam. This material deforms under pressure but only returns to its original shape with some delay. This makes the material attractive for use in mattresses or pillows because it gives a soft and comfortable feeling but with good support, whereby a springy effect is avoided.

However, factors that make it unattractive for use in these applications are the fact that the compressibility characteristics are highly temperature dependent, so that the feeling of comfort varies greatly between summer and winter, and the fact that many pores in viscoelastic foam are closed pores, such that this material has a very poor permeability to air and thus enables limited moisture absorption and emission in an article in which it is used.

Another known foam is reticulated foam. This means that it is rather a net-like foam, whereby there are few, if any, thin membranes in the foam, such that the material has very good permeability to air, and thus also very good moisture exchange characteristics.

Such a reticulated foam can be made for example by filling the cells of a traditional PU foam with an explosive gas and allowing it to explode, such that the walls of the cells in the foam are burned, broken and/or removed by the heat and/or force.

However it is also possible to obtain reticulated foams in other ways. However, such reticulated foams generally have poor compressibility properties. In practice they are too soft, and are thus already fully compressed under a low load, to be widely used in the said applications.

The purpose of the present invention is to provide a solution to at least one of the aforementioned and other disadvantages, by providing a multi-layered material that at least comprises a first layer and a second layer bonded thereto, whereby both layers are made from flexible foam and the first layer is made from a foam with a greater permeability to air than the foam of the second layer, and whereby the second layer has openings that run across the entire thickness of the second layer in order to enable air exchange between the first layer and the second layer.

The permeability to air is hereby a measure of the ease with which air can flow through the foam. This can be considered as a permeability value, or a value derived from it, for the foam as used in the known Darcy equation.

The permeability to air as a general concept can also be expressed as a pressure drop, i.e. a resistance to the flow of air that is measured on a foam in standardised conditions, for example according to ISO standard 9237:1995.

Hereby a high pressure drop indicates that the material has a low permeability to air and a low pressure drop that the material has a high permeability to air. On the basis of theoretical considerations and/or experimental models a permeability value can also be approximately determined on the basis of a number of parameters of the foam, whereby the most important are: the size and fraction of pores and the total porosity.

Preferably the foam of the first layer has a pressure drop, measured according to ISO 9237:1995, that is less than 1 kPa, more preferably less than 0.5 kPa, and even more preferably less than 0.1 kPa .

Preferably the foam of the second layer has a pressure drop, measured according to ISO 9237:1995, that is greater than 1 kPa, preferably greater than 2 kPa, and even more preferably greater than 3 kPa.

Thanks to the invention the advantage of a favourable elastic-mechanical behaviour of a foam, for example a viscoelastic foam, can be combined with a good air permeability of a different type of foam, in order to give both good properties to a piece of the multi-layered material .

If the material is used in an orientation in which the openings primarily extend vertically, a chimney effect can even be obtained whereby the moisture emission is even better .

In a preferred embodiment the first layer is made of reticulated foam. This gives outstandingly good results relating to moisture absorption and moisture emission. This result is even better if the reticulated foam is hydrophilic.

In a further preferred embodiment the first layer is provided with cutaways that connect to the openings in the second layer.

This material has the advantage that it is easy to make using a standard profiling machine, and that it has an improved permeability to air and moisture due to the cutaways, which together with the openings define preferred air displacement channels.

In a further preferred embodiment the cutaways in the first layer do not continue to the surface of the first layer turned away from the second layer, such that this prevents the cutaways from forming starting points for tearing on this surface.

In a further preferred embodiment the openings in the second layer are wider in the direction away from the first layer .

This also means that the foam parts in this same direction are smaller. As a result a self-compensating effect is obtained for temperature variations, which as is known greatly change the mechanical behaviour of a viscoelastic foam.

As a result of this shape a part of the foam parts where they are thin will provide the desired balance between softness and support at a low temperature when the foam parts are harder, while at a high temperature the foam parts are softer, and the thinner parts are practically fully compacted, whereby a thicker part of the foam parts will provide this balance.

In a further preferred embodiment the openings in the second layer constitute between 67% and 150% of the volume of the foam of the second layer, and preferably close to 100%.

This has advantages because in this way two sheets of identical multi-layered material according to the invention can be made from a three-layered starting piece, such that less waste is generated during production.

The invention also comprises a mattress, a mattress topper, a pillow or a cushion that comprises at least one layer of the said material according to the invention, whereby the layer of material is oriented such that the second layer is oriented inwards, in other words in which the second layer is oriented in the direction of the core of such an article, in other words in which the first layer is intended to be the closest to the body of the user during use.

Thanks to the material according to the invention, such an article acquires a good combination of comfort and support for the user, and also good moisture management. Furthermore the invention concerns a method for manufacturing such a multi-layered material that comprises the following steps: the composition of a multi-layered composite flexible layer of at least three layers of flexible foam bonded together; the cutting of the middle layer of the three layers to form two separate layers of the material, whereby the applied cut essentially runs through the middle layer of the three layers and also continues locally up to each of the outermost layers of the three layers.

Through this method very specific layered products can be made very easily.

In a preferred embodiment the cutting of the middle layer of the three layers is done in a profiling machine with simultaneous deformation of the composite layer, whereby the position and form of the cut is controlled by the thicknesses of the layers and the settings of the profiling machine .

Such a profiling machine is a known machine in the field of foam processing and is also known as a 'convoluting machine' . This is a machine that variably impresses a foam layer locally by means of profiled rollers, after which this layer is cut in the impressed state to form two profiled foam layers. As a result of the variable impression, which presents a regular pattern over the surface, a profiling with a complementary pattern is obtained on the foam layers. Such a machine is described in US 4603445 for example. In a preferred embodiment the three layers are chosen such that the two outer layers of the three layers have a permeability to air that is greater than the permeability to air of the middle layer of these three layers, such that a material is obtained that satisfies the requirements for a material according to the invention as described above.

In a further preferred embodiment the middle layer is made of viscoelastic foam and the outermost layers of reticulated foam.

This gives optimum behaviour, both elastically-mechanically and with regard to moisture management.

With the intention of better showing the characteristics of the invention, a preferred embodiment of a material according to the invention, a method for manufacturing this and a mattress according to the invention, are described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein :

Figure 1 schematically shows a perspective view of a piece of material according to the invention;

figure 2 shows a cross-section of the piece of material of figure 1 according to the line II-II;

figure.3 shows a method for manufacturing the material of figures 1 and 2;

figure 4 shows a cross-section of a variant of a material according to the invention; figure 5 shows a perspective view of another variant of a material according to the method;

figure 6 shows a mattress in which the material of figure 4 is used; and

figures 7 and 8 show variants of a mattress in which the material of figure 4 is used.

The material 1 shown in figures 1 and 2 in this example consists of three layers, i.e. a first layer 2, a second layer 3, and a third layer 4, whereby the second layer 3 is between the other two layers .

The first layer 2 is a continuous layer with cutaways 5 that do not continue to the surface 6 of this first layer 2 that is turned away from the second layer 3. The first layer is made from a reticulated polyurethane foam with a high permeability to air. This is clear from the low pressure drop of < 0.1 kPa, measured on this material according to ISO 9237:1995.

As is especially clear from figure 2, which shows a cross- section through the second layer 3 in the direction of the first layer 2, the second layer 3 is a continuous layer that is formed by foam parts 7 and openings 8 between these foam parts 7 that run through the entire thickness D of the second layer 3. The foam parts 7 are thinner in the direction of the first layer 2 towards the third layer 4, and the openings 8 are correspondingly larger in this direction. The second layer 3 is made of a viscoelastic polyurethane foam. This viscoelastic foam has a low permeability to air. This is clear from the high pressure drop of 5.3 kPa, measured on this material according to ISO 9237:1995. The third layer 4 is a discontinuous layer consisting of foam caps 9 that are made from the same foam as the first layer 1 and which are on the foam parts 7.

On account of the relatively closed cell structure of the viscoelastic foam from which the second layer 3 is made, and the very open cell structure of the reticulated foam from which the other two layers 2,4- are made, the foam of the . first layer 2 has a much higher permeability to air than the foam of the second layer 3.

The material 1 can be manufactured in the following way:

First a three-layered flexible composite layer 10 is manufactured by bonding a flexible middle layer 11 of viscoelastic foam between two flexible outer layers 12 of reticulated foam.

Then this composite layer 10 is guided by a profiling machine, i.e. a convoluting machine'. Such a machine comprises two rollers 13 with regularly positioned projections 14 between which the composite layer 10 is guided.

The composite layer 10 is compressed locally by the projections 14 and also moved forward in the direction of the arrow P. While the composite layer 10 is still in a compressed state, it is cut with a blade 15.

The settings of the profiling machine, such as for example the geometry of the projections 14, the distance between the rollers 13 mutually and between the rollers 13 and the blade 15 are chosen such that the cut that the blade 15 makes is transverse through the middle layer 11, and also locally, where the deformation of the composite layer 10 by the projections 14 is the greatest, continuing up to the outer layers 12. These settings of course depend on the thickness of the middle layer 11 and the outer layers 12.

In this example, but not necessarily, the composite layer 10 is symmetrical and the blade 15 is at an equal distance from each roller 13, so that a symmetrical cut is made, and as a result of this two identical pieces of material 1 are obtained . Other settings and other composite layers 10 are of course also possible and will lead to variants.

The alternative embodiment of the material 1 as shown in figure 4 differs from the embodiment of figures 1 and 2 described above because it only consists of two layers, i.e. a first layer 2 and a second layer 3.

This alternative embodiment can be manufactured by, in the method described above, successively removing the foam caps 9 and possibly a part of the foam parts 7, for example by cutting them off. The alternative embodiment of the material 1 shown in figure 5 differs from the embodiment of figures 1 and 2 described above, because in this case the openings 8 are channel-shaped openings 16.

This embodiment can be made by guiding the composite layer 10 through a contour cutting machine, whereby the settings of the contour cutting machine are such that a cut goes back and forth through the middle layer 11, and hereby also by through sections of the outer layers 12.

Such a contour cutting machine is known in the field of foam processing, and comprises a band knife whose orientation can be varied, in order to cut the correct contours in this way.

The material 1 of figure 5 can, with or without the complementary material 1 that is formed during such a cutting operation, and which is not shown in figure 5, be guided again through the contour cutting machine in a direction perpendicular to the direction in which it is worked the first time, so that channels perpendicular to the channel shaped openings 16 also occur, which can only be in the middle layer 11, or also in the outer layers 12.

The mattress 17 shown as a cross-section in figure 6 essentially consists of two layers of material 1 according to the invention, whereby the second layer 3 is oriented inwards . When a person lies on such a mattress 17, the first layer 2 will be easily compressed and a gives a soft feeling, while the second layer will present its viscoelastic behaviour and the person will be given a support that is adjusted to the pressure that is exerted locally.

Thanks to the openings 8 that continue from the first layer 2, whose material has good permeability to air, through the second layer 3, whose material does not have that, the mattress 17 can absorb moisture produced by the user while using the mattress 17, and can also emit that moisture through openings 8 other than on which the person is lying, or when the mattress 17 is not used. As a result problems with moisture accumulation in the mattress 17. and insufficient absorption of moisture can be prevented.

In a similar way a pillow can also be made, albeit with foams with different compressibility characteristics and of course in a different size.

It is useful here to provide these pillows with a cavity , accessible from the side of the pillow, for example formed by a textile cover or textile bag that is affixed between both layers of material 1.

A sound-producing device such as a telephone, MP3 player or an alarm, can be placed in it, whereby thanks to the openings 8 in the layers of material, the sound produced is hardly damped, if at all, but conveyed and spread over the pillow, so that the user of the pillow can hear the sound optimally .

In variants, as shown in figures 7 and 8, a supporting layer 18 of reticulated foam is placed between the two layers of material 1 according to the invention. This is primarily used in order to have some flexibility relating to the precise positioning of the foam parts 7 on one another, so that the manufacture of such a mattress 17 becomes easier.

This also enables, as specifically demonstrated in figure 8, the foam parts 7 of a layer of the material 1 to be placed on the openings 8 in the other layer of material 1.

The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but such a method, material and mattress or other article with the material can be realised in all kinds of variants, without departing from the scope of the invention .

Claims

Claims .

1.- Multi-layered material (1) that at least comprises a first layer (2) and a second layer (3) bonded thereto, whereby both layers (2,3) are made from flexible foam and the first layer (2) is made from a foam with a greater permeability to air than the foam of the second layer (3), and whereby the second layer (3) has openings (8) that run across the entire thickness of the second layer (3) in order to enable air exchange between the first layer and the second layer.

2.- Material (1) according to claim 1, characterised in that the foam of the first layer (2) has a resistance to air flow that is less than 50% of the resistance to air flow of the foam of the second layer (3), when the resistance to air flow of the foams of both layers (2,3) is measured in the same way.

3. - Material (1) according to claim 1 of 2, characterised in that the foam of the first layer (2) has a pressure drop, measured according to ISO 9237:1995, that is less than 1 KPa.

4. - Material (1) according to any one of the previous claims, characterised in that the foam of the second layer (4) has a pressure drop, measured according to ISO 9237:1995, that is greater than 1 KPa.

5.- Material (1) according to any one of the previous claims, characterised in that the first layer (2) is made of reticulated foam.

6.- Material (1) according to any one of the previous claims, characterised in that the second layer (3) is made of viscoelastic foam.

7. - Material (1) according to any one of the previous claims, characterised in that the first layer (2) is provided with cutaways (5) that connect to the openings (8) in the second layer (3) and which do not continue to the surface (6) of the first layer (2) turned away from the second layer ( 3 ) .

8. - Material (1) according to any one of the previous claims, characterised in that the openings (8) in the second layer (3) widen in the direction away from the first layer (2 ) .

9. - Mattress (17) that comprises at least one layer of material (1) according to any one of the previous claims, whereby the layer of material (1) is oriented such that the first layer (2) of foam is oriented towards the side that is intended to be used by a person for lying on.

10. - Mattress according to claim 9, characterised in that it comprises two layers of material (1) according to any one of the claims 1 to 9, whereby both layers of material (1) are turned towards one another with their second layer (3) of flexible foam.

11.- Mattress topper that comprises at least one layer of material (1) according to any one of the claims 1 to 8, whereby the layer of material (1) is oriented in such a way that the first layer (2) of foam is oriented towards the side that is intended to be used by a person for lying on.

12. - Pillow that comprises at least one layer of material

(1) according to any one of the claims 1 to 8, whereby the layer of material (1) is oriented such. that the first layer

(2) of foam is oriented towards the side that is intended to be used by a. person for laying his head on..

13. - Pillow that comprises two layers of material (1) according to any one of the claims 1 to 8, whereby both layers of material (1) are turned towards one another with their second layer (3) of flexible foam.

14. Pillow according to claim 12 or 13, characterised in that it is provided with a cavity for a sound-producing device, and this cavity is accessible from the outside of the pillow.

15. - Cushion that comprises at least one layer of material (1) according to any one of the claims 1 to 7, whereby the layer of material (1) is oriented such that the first layer (2) of foam is oriented towards the side that is intended to be used by a person for resting his body on or against it.

16. - Method for manufacturing a multi-layered material (1) that comprises the following steps: the composition of a multi-layered composite flexible layer (10) of at least three layers (11, 12) of flexible foam bonded together; the cutting of the middle layer (11) of the three layers (11, 12) to form two separate layers of the material (1), whereby the applied cut essentially runs through the middle layer (11) of the three layers (11, 12) and also continues locally up to each of the outermost layers (12) of the three layers (11, 12), characterised in that the two outermost layers (12) of the three layers (11, 12) have a permeability to- air that is greater than the permeability to air of the middle layer (11) of these three layers (11, 12) .

17. - Method according to claim 16, characterised in that the cutting of the middle layer (11) of the three layers

(11, 12) is done in a profiling machine with simultaneous deformation of the composite layer (10), whereby the position and shape of the cut is controlled by the thicknesses of the layers (11, 12) and the settings of the profiling machine.

18. - Method according to claim 17, characterised in that the profiling machine has two profiled rollers (13) to compress a layer of flexible foam location-dependently by guiding it between the rollers, whereby the settings of the profiling machine comprise the geometry of the profiling of the rollers (13) and the distance of the rollers (13) from one another.

19.- Method according to claim 16, characterised in that the cutting of the middle layer (11) of the three layers (11, 12) is done in a contour cutting machine whereby the position and shape of the cut is controlled by the settings of the contour cutting machine

20.- Method according to claim 19, characterised in that the composite layer 10 is guided successively in two unequal directions by the contour cutting machine.

21.- Method according to any one of the claims 13 to 17, characterised in that the outermost layers (12) of the three layers (11, 12) are made from reticulated foam and the middle layer (11) of the three layers (11, 12) is made from viscoelastic foam.