State of the art

Multilayered fabrics are used for manufacturing mattresses, pillows, seats and upholstered furniture. These fabrics are made so as to have either flameproof or waterproof features. There are currently no fabrics on the market, which have combined effective flameproof and waterproof features.

Most of the above mentioned fabrics are produced starting from a woven or non-woven fabric, to which a previously formed film of PVC or polyurethane is applied by means of lamination.

These fabrics suffer from the drawback that the PVC/polyurethane film must be rather thick in order to achieve its function. This implies high material consumption .

A further disadvantage of these fabrics is that, in order to obtain the required mechanical, waterproof, flameproof or aesthetical features, toxic substances - or at least substances which are not completely non-toxic - must be used, thus rendering the final fabrics unsuitable to be used for children's mattresses or furniture.

Yet another disadvantage of these fabrics is that it is difficult to obtain an optimal printing on the surface thereof. This is because the external film of the fabric is so smooth that the printing ink is not retained appropriately on its surface and tends to fade, the resulting picture on the fabric remaining undefined.

Moreover, the method for producing such fabrics has the disadvantage that it is expensive because it implies first forming the PVC/polyurethane film and then adhering the formed film to the underlying woven or non-woven fabric. Further, the results obtained by this production method are often not satisfactory in terms of resistance, impermeability and aesthetics.

An object of the present invention is therefore to provide a method for producing a flameproof and waterproof multilayer fabric or a waterproof multilayer fabric that solves at least one of the above drawbacks in a simple, efficient and cost-effective manner.

This object is achieved by the present invention as it relates to a method as defined in claim 1.

It is a further object of the present invention to provide a flameproof and waterproof multilayer fabric as defined in claim 17 and a waterproof multilayer fabric as defined in claim 36. Definitions

Unless defined otherwise, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although many methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, preferred methods and materials are described below. Unless mentioned otherwise, the techniques described herein for use with the invention are standard methodologies well known to persons of ordinary skill in the art.

By the term "flameproof" there is intended a fabric which is non-flammable, i.e. a fabric that blocks flames, prevents the propagation of fire, remains intact even if burnt and maintains enough dimensional stability when subjected to heat or flames.

By the term "waterproof" there is intended a fabric which is impervious to water even when the water is applied with a considerable pressure.

By the term "stitch-bonded fabric" there is intended a non-woven web of fibre with overlaid longitudinal stitching that provides a woven appearance and performance. In particular the stitch-bonded fabric maintains a texture as soft as the original fabric, has an improved resistance and is aesthetically pleasant. Moreover, the method for producing stitch-bonded fabric is cost-effective.

Brief description of the drawings Figure 1A shows an enlarged image of a flameproof and waterproof multilayer fabric of the present invention seen on the side of a first layer of non-woven stitch-bonded fabric .

Figure IB shows an enlarged image of the flameproof and waterproof multilayer fabric of the present invention seen on the side opposite to that shown in Figure 1A.

Figure 2A shows a sectional view of the first layer of stitch-bonded fabric of Figure 1A. The second and third layers of the flameproof and waterproof multilayer fabric and the stichbonding thread of the stitch-bonded fabric are not shown for convenience.

Figure 2B shows a sectional view of the first, second and third layers of the flameproof and waterproof multilayer fabric of Figure 1A and IB.

Figure 3 shows a perspective view of a propane gas burner with a mattress beside for use in the thermographic analysis of a flame test for the fabrics of the invention.

Figures 4A, 4B, 4C respectively show images at different time points (t=0 s, t=30 s, t=5 min) of a thermographic analysis of a flame test for the fabrics of the invention.

Detailed description

The method according to the present invention for producing a flameproof and waterproof multilayer fabric or a waterproof multilayer fabric comprises steps (a) to (f) .

In step (a) at least one first layer comprising a woven or non-woven fabric is provided. The at least one first layer preferably comprises a non-woven stitch-bonded fabric. The woven or non-woven fabric preferably comprises a material selected from the group consisting of viscose fibres, intrinsically flame retardant viscose fibres, flame retardant treated viscose fibres, cotton fibres, flame retardant cotton fibres, flame retardant treated cotton fibres, melamine fibres, polyester fibres, low-melt polyester fibres, modacrylic fibres, para-aramid fibres, polyacrylate , PAN-carbon fibres, basalt fibres, silica fibres, textile glass fibres and mixtures thereof.

More preferably, the woven or non-woven fabric comprises intrinsically flame retardant viscose fibres.

As an alternative, the woven or non-woven fabric comprises polyester fibres.

In step (b) , at least one second layer comprising at least one material selected from the group consisting of acrylic resin, stiren-butadien-rubber (SBR) , ethylene-vinyl acetate resin, polyurethane resin, vinyl resin, acrylonitrile resin and vinyl-versatic resin is doctored, i.e. applied by a doctor blade, over the at least one first layer. Thereby an at least two-layered fabric is obtained.

The at least one second layer preferably comprises an acrylic resin.

In step (c) , the at least one second layer of the at least two-layered fabric obtained in step (b) is foamed at a temperature from 90°C to 110°C. More specifically, the at least two-layered fabric obtained in step (b) passes through an oven which is heated at the necessary temperature. This allows the material of the second layer to dry in an amorphous state and form a certain amount of air bubbles therein. As can be noted from a comparison of Figures 2A and 2B, the foamed second layer fills the cavities formed in the non-woven stitch-bonded fabric by the stitchbonding thread and concurs to build a barrier that hinders the transit of water through the two-layered fabric obtained in step (c) . The temperature from 90°C to 110°C allows not to crosslink the material of the second layer, but instead to obtain a foamed amorphous layer.

As the person skilled in the art will understand, step (c) has a variable duration depending on the temperature of the oven, the length of the machinery used to carry out step (c) and the amount of water included in the material of the second layer as applied in step (b) .

In step (d) , the at least two-layered fabric obtained in step (c) is cold calendered. Thereby, a consistent part of the air bubbles in the foamed second layer is released and the second layer becomes thinner and better adheres to the first layer. Moreover, eliminating a consistent part of the air bubbles leads to the fact that comburent (O ₂ ) is removed and, in case of fire, this results in a multilayered fabric including a layer that not only avoids propagation of flames, but also serves as a barrier to flames . The combination of steps (b) , (c) and (d) allows, among other things, to obtain a particularly flexible material .

In step (e) , at least one third layer comprising at least one material selected from the group consisting of polyurethane resin, acrylic resin, stirol-acrylic resin, vinyl-acrylic resin, ethyl-vinyl-acrylic resin, stiren- butadien-rubber (SBR) , ethylene-vinyl acetate resin, vinyl resin, acrylonitrile resin and vinyl-versatic resin is doctored over the at least one second layer of the at least two-layered fabric calendered in step (d) . Thereby, an at least three-layered fabric is obtained. Step (e) allows to form a particularly thin third layer.

The at least one third layer preferably comprises a polyurethane resin.

In step (f), the at least three-layered fabric obtained in step (e) is heat-setted at a temperature from 120°C to 180°C, preferably at a temperature of about 160°C. Step (f) preferably has a duration from 30 s to 50 s, more preferably a duration of about 40 s. In step (f) , the third layer as well as the second layer are crossed-linked . This allows to form a particularly efficient barrier both against water and against fire.

The method according to the present invention preferably also comprises a step (g) of printing the at least one second layer of the at least two-layered fabric obtained in step (c) . Step (g) is performed after step (c) and before step (d) . This allows an optimal printing of the fabric because the second layer is not excessively smooth and can therefore retain the printed ink without the borders of the printed image becoming blurred.

Step (g) is preferably performed at a temperature from

90°C to 110°C so as not to induce crosslinking of the material of the second layer, which should be performed later in step (f) .

From the above disclosure, it should be clear that the method according to the present invention allows to obtain a fabric that has specific optimal intrinsic properties resulting from the specific steps of the method.

With reference to Figure 2A and 2B, the flameproof and waterproof multilayer fabric obtained by the above disclosed method comprises at least one first layer 1, one second layer 2 and one third layer 3. The overall appearance of multilayer fabric as seen on the side of first layer 1 is shown in Figure 1A, whereas the overall appearance of the fabric as seen on the side of third layer 3 is shown in Figure IB.

First layer 1 comprises a woven or non-woven fabric. First layer 1 preferably comprises a non-woven stitch- bonded fabric, which is typically soft, resistant and has good aesthetical appearance. The woven or non-woven fabric preferably comprises a material selected from the group consisting of viscose fibres, intrinsically flame retardant viscose fibres, flame retardant treated viscose fibres, cotton fibres, flame retardant cotton fibres, flame retardant treated cotton fibres, melamine fibres, polyester fibres, low-melt polyester fibres, modacrylic fibres, para- aramid fibres, polyacrylate, PAN-carbon fibres, basalt fibres, silica fibres, textile glass fibres and mixtures thereof. More preferably, the woven or non-woven fabric comprises intrinsically flame retardant viscose fibres. The particular advantage of intrinsically flame retardant viscose fibres is that they are flameproof.

First layer 1 preferably has a weight from 100 to 220 g/m ² , more preferably a weight from 130 to 190 g/m ² , even more preferably a weight of about 160 g/m ² .

Second layer 2 comprises at least one material selected from the group consisting of acrylic resin, stiren-butadien-rubber (SBR) , ethylene-vinyl acetate resin, polyurethane resin, vinyl resin, acrylonitrile resin and vinyl-versatic resin. More preferably, second layer 2 comprises an acrylic resin.

Second layer 2 preferably has a weight from 30 to 50 g/m ² , more preferably a weight of about 40 g/m ² . It should be understood that the above weights of second layer 2 refer to the dry material, i.e. the material which has already undergone step (c) .

Third layer 3 comprises at least one material selected from the group consisting of polyurethane resin, acrylic resin, stirol-acrylic resin, vinyl-acrylic resin, ethyl- vinyl-acrylic resin, stiren-butadien-rubber (SBR), ethylene-vinyl acetate resin, vinyl resin, acrylonitrile resin and vinyl-versatic resin. Preferably the third layer comprises a polyurethane resin.

Third layer 3 preferably has a weight of from 30 to 40 g/m ² , more preferably about 35 g/m ² .

The overall weight of the fabric is preferably more than 160 g/m ² , more preferably more than 210 g/m ² , even more preferably, the overall weight of the fabric is about 240 g/m ² .

It should be understood that optional printing step

(g) can add a weight of about 2 g/m ² , to the overall weight of the fabric.

A particularly soft, resistant, waterproof and flameproof multilayer fabric was obtained by using intrinsically flame retardant viscose fibres as the non- woven stitch-bonded fabric, an acrylic resin as the second layer and a polyurethane resin as the third layer, the overall weight of the fabric being about 240 g/m ² . The thickness of the above mentioned fabric is 550 pm as measured by DIN EN 1942 standard.

The above disclosed waterproof and flameproof multilayer fabric is used to manufacture mattresses, pillows, seats and upholstered furniture. In particular, the above multilayer fabric is particularly suitable for items to be used by children, as it contains no toxic or even potentially toxic materials.

The present invention further relates to a waterproof multilayer fabric, which is obtained by the above disclosed method and comprises at least one first layer, one second layer and one third layer.

The first layer comprises a woven or non-woven fabric comprising polyester fibres, by which a particularly resistant waterproof multilayer fabric can be obtained. The second and third layers comprise the materials disclosed above for the flameproof and waterproof multilayer fabric of the present invention.

An additional layer of fluorocarbon resin having a weight of about 2 g/m ² may be added to the waterproof multilayer fabric in order to increase its performances.

The overall weight of the waterproof multilayer fabric is about 140 g/m ² .

The thickness of the above mentioned fabric is 320 pm as measured by DIN EN 1942 standard.

The above waterproof multilayer fabric is used to manufacture waterproof covers which require particular mechanical resistance. In particular, the waterproof multilayer fabric is used to manufacture covers for boats and more in general for the boat and naval industry. Similarly, it may be used for sun umbrellas, swimming pools and to cover any outdoor facility.

Examples

Example 1

Fabrics having different weights, obtained by the method according to the present invention and obtained by using a non-woven stitch-bonded intrinsically flame retardant viscose fibre fabric as first layer, an acrylic resin as second layer and polyurethane resin as third layer, were tested to evaluate performances when subjected to a water column of different height.

The results showed that a fabric having an overall weight of at least 160 g/m ² is waterproof when subjected to a column of 110 mm of water and a fabric having an overall weight of at least 210 g/m ² is waterproof when subjected to a column of 1110 mm of water.

Example 2

The behaviour of the fabrics of the present invention was tested by applying a vertical propane gas flame for 50 seconds to a mattress manufactured by using an inflammable polyurethane foam as a filling and fabrics having different weights, obtained by the method according to the present invention and obtained by using a non-woven stitch-bonded intrinsically flame retardant viscose fibre fabric as first layer, an acrylic resin as second layer and polyurethane resin as third layer.

For the sake of conciseness, only the results obtained by using a fabric having an overall weight of 240 g/m ² is shown in Figure 5 and disclosed hereinafter. However, it must be noted that very similar results were obtained even with lighter fabrics and with fabrics having a different composition of the three layers.

Figure 3 shows a system for carrying out thermographic analyses of a flame test for the fabrics of the invention.

In particular, a propane gas burner is shown on the right.

The propane burner has a series of nozzles for the gas to exit. A mattress is shown on the left, which can be pulled close to the burner and come into contact with the flame once the burner is lighted.

Figure 4 shows subsequent images taken with a FLIR infrared camera at three time points of the flame test.

Figure 4A shows the situation at t=0 s, i.e. just as the burner has been lit. The surface of the mattress, i.e. the fabric according to the present invention, comes into contact with the flame. Figure 4B shows the situation at t=30 s. The surface of the mattress is licked by the flame.

At t=50 s, the burner is put out. Figure 4C shows the situation at t=5 min. The surface of the mattress is damaged by the flame, but has not caught fire itself.

From the above disclosed results, it is apparent that, when the flame is extinguished, the fabric has served as a barrier for the flame. As a matter of fact, the flame does not propagate to the internal layers of the mattress. The surface combustion of the fabric extinguishes on its own once the external source of the flame is put out.

From an analysis of the features of the method and of the multilayer fabric according to the present invention the advantages it allows to achieve are apparent.

In particular, the method according to the invention is simple, fast and cost-effective to implement, it allows considerable saving in material and further allows a particularly effective printing of the fabric.

Further, the flameproof and waterproof multilayer fabric of the invention provides a safe and reliable barrier against flames and water, as clearly shown in the examples. The fabric also displays optimal mechanical properties, results soft and aesthetically pleasant and is completely non-toxic. The fabric also provides an optimal support for printing.

Further, the waterproof multilayer fabric of the invention provides a resistant and reliable protection against water.

Finally, it is clear that modifications and variants to the method and fabric disclosed and shown may be made without because of this departing from the scope of protection of the appended claims.