The present invention refers to a protecting membrane and to processes for manufacturing a protecting membrane.

A textile membrane comprising a composite of a polymeric material and a ceramic material is known from EP-A-1 816 254, of the same Applicants of the present invention.

This membrane has the advantage, when worn by a user, of absorbing the infrared rays emitted by the body and then reflecting them towards the body, thereby heating it with beneficial health results.

However, this membrane is not completely insulating and part of the above infrared rays are anyway dispersed outside, not providing the best possible effect for the wearer.

Object of the present invention is solving the above prior-art problems, by providing a protecting membrane that is an improvement of the above textile membrane in that it uses at least one further layer whose function is insulating the body (the term "body" being here used to mean every body of a person, animal or object protected by the membrane) and emitting towards the body also infrared rays that escape through the above textile membrane made of ceramics .

Another object of the present invention is providing a protecting membrane that can be used in a wide number of fields, a few examples of which are the textile field (like the previous membrane) , the building field, namely the roofing and heating fields, the agricultural field and the foodstuff field.

Another object of the present invention is providing some processes for manufacturing a protecting · membrane as outlined above that are simple, quick, inexpensive, efficient and effective .

The above and other objects and advantages of the invention, as will appear from the following description, are obtained by a protecting membrane and processes for manufacturing a protecting membrane as claimed in the respective independent claims. Preferred embodiments and non-trivial variations of the present invention are claimed in the dependent Claims.

It is intended that all enclosed claims are an integral part of the present disclosure.

The present invention will be better described by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed drawings, in which Figures 1, 2 and 3 are schematic side views of three possible embodiments of the protecting membrane of the invention.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) could be made to what is described, without departing from the scope of the invention as appears from the enclosed claims.

With reference to the Figures, the protecting membrane 1 of the present invention substantially comprises at least one infrared-ray-emitting layer 3 and at least one infrared-ray-reflecting layer 5 in contact with the infrared-ray-emitting layer 3.

In a preferred configuration, the infrared- ray-reflecting layer 5 is made of a composite material comprising aluminium particles dispersed into a polymer-based matrix, aluminium representing 5 to 60% in mass of the composite material. In another preferred configuration, the infrared-ray-emitting layer 3 is made of a composite material comprising ceramic particles dispersed into a polymer-based matrix, the ceramics representing 1 to 60% in mass of the composite material .

The polymer-based matrix is usually made of polyurethane, polyester or thermoplastic polymers.

Moreover, the polymer-based matrix can further comprise flame-retardant additives, which preferably are antimony trioxide, halogens, or other materials.

In its widest application, the above protecting membrane 1 is adapted to be used in the textile field for totally or partially covering a person or an animal.

For this end application, in a first possible, non-limiting embodiment (shown in Figure 2), the membrane 1 is made of a sequence of overlapping layers ordered as: a woven or non-woven layer 7, overlapped to an attachment layer 9 (namely a layer that allows attaching the woven or non-woven layer to the infrared-ray-emitting layer and/or to the infrared-ray-reflecting layer) , in turn overlapped to the infrared-ray-reflecting layer 5, in turn overlapped to the infrared-ray-emitting layer 3.

Always for the above end application, in a second possible, non-limiting embodiment (shown in Figure 3) , the membrane 1 is made of a sequence of overlapping layers ordered as : a first woven or non-woven layer 7, overlapped to a first attachment layer 9, in turn overlapped to the infrared-ray- emitting layer 3, in turn overlapped to the infrared-ray-reflecting layer 5, in turn overlapped to a second attachment layer 11, in turn overlapped to a second woven or non-woven layer 13.

The attachment layers 9, 11 as described above can be made of foam, or paste, or dots, or thermoplastic web, or other materials.

As stated above, the inventive protecting membrane 1· can also be used in the building field for providing roofing insulation or wall insulation or covering a heating system in order to avoid heat loss through a wall; or it can be used in the agriculture field, or in the foodstuff field.

The above protecting membrane 1 can be manufactured with a few different processes, which are described below (also through non-limiting examples thereof) , the first one of which comprises the steps of: preparing a mixture of hydrophilic polyurethane on a solvent base containing a pigment of aluminium particles;

applying the mixture on a silicone release paper, preferably using a knife on roller on a coating line;

drying in an oven, preferably at 100 °C, to evaporate the solvent in order to finally obtain a dry film layer;

preparing a second mixture of polyurethane solvent base containing a mixture of ceramic particles in liquid form;

coating the release paper, together with the layer of polyurethane added with aluminium, with the second mixture of polyurethane solvent in liquid form, preferably using a knife on roller;

drying the liquid mixture of polyurethane in an oven, preferably at 100 °C, to evaporate the solvent, in order to obtain a dry film layer ;

crosslinking, preferably at 160 °C, the release paper together with the first layer of polyurethane and aluminium, and the second layer of polyurethane and ceramics; and separating the release paper from the film.

In order to manufacture the above membrane 1 in its application in the textile field, the above process further comprises the steps of winding up the film on a cardboard tube, and laminating the film to a woven or non-woven textile.

Preferably, the step of laminating is performed through a hot melt dot lamination, by applying 100% solid melted glue on the membrane 1 and laminating the membrane 1 onto the woven or non-woven textile.

Still preferably, the step of laminating is performed through a foaming lamination process using a coating line, foaming being performed by putting ai-r inside a mixture of various polymers composing a glue, and applying this foamed polymer onto a fabric, preferably with a knife on roller, and then performing a wet or dry lamination.

Regarding the preferred sizes of the materials to be used with the above membrane 1 and process, the average size of the aluminium particles ranges from 10 micron to 85 micron, preferably 35 or 65 micron according to the end use of the membrane 1 Moreover, the concentration of the aluminium pigment ranges from 5% to 60% in dry weight with respect to the weight of the polyurethane, while preferably the concentration of the aluminium pigment is 30% in dry weight with respect to the weight of the polyurethane.

Moreover, the dry weight of the aluminium coating layer ranges from 5 g/m ² to 30 g/m ² , preferably 15 g/m ² .

Still more, the dry weight of the layer of ceramics ranges from 5 g/m ² to 30 g/m ² , preferably 20 g/m ² .

According to a preferred example for performing the above process, a mixture of hydrophilic polyurethane was prepared on a solvent base containing a pigment of aluminium particles, as follows:

providing 30% of dry contents of polyurethane based on solvent isobutyl alcohol and toluol; - adding 3.5 parts of polyisocianate cross- linker;

adding 15% of isobutyl alcohol and 15% of toluol;

adding 15% of aluminium pigment with 70% of dry contents; and thoroughly mixing the above components.

This mixture was applied with the principle of the knife on roller on a silicone release paper with a traditional coating line; after application, the liquid mixture of polyurethane was dried in an oven at around 100 °C to evaporate the solvent to obtain, in the end, a dry film layer. The dry weight of this layer of aluminium coat was around 15 g/m ² , and this release paper, together with the layer of polyurethane added with aluminium, was coated again through a knife on roller with a second mixture of polyurethane solvent base in liquid form.

The second mixture of polyurethane solvent in liquid form was prepared as follows:

providing 30% of dry contents of polyurethane based on solvent isobutyl alcohol and toluol; adding 3.5 parts of polyisocianate cross- linker;

adding 15% of isobutyl alcohol and 15% of toluol ;

adding 15% of a blend of ceramics with 70% of dry contents; and

thoroughly mixing the above components. The liquid mixture of polyurethane was dried in an oven at around 100 °C to evaporate the solvent, to obtain finally a dry film layer; afterwards, the release paper together with the first layer of polyurethane and aluminium and the second layer of polyurethane and ceramics was cross-linked at around 160 °C: the dry weight of this layer of ceramic coat was 20 g/m ² .

At the end of this process, the release paper was separated form the film; the film was wound on a cardboard tube, and this final film on a cardboard tube was laminated to a textile. The lamination was made with one of two different methods: hot melt dot lamination, by applying 100% solid melted glue on the membrane 1 and laminating this membrane 1 on the textile (it is also possible to perform the process inversely) ; or a foam lamination process, using a traditional coating line: in this phase, foaming was made by putting air inside a mixture of several polymers composing the glue, and applying this foamed polymer with a knife on roller to the fabric and afterwards making a wet or dry lamination.

Summarising, a variation of the process for manufacturing a protecting membrane 1 for textile applications comprises the steps of:

- providing a woven or non-woven textile substrate;

- coating a first layer of water-based or solvent-based compound directly on the textile substrate ;

- if the textile substrate is used as an outer layer, firstly applying onto the substrate a coating made of polyurethane with aluminium particles, and secondly applying onto the substrate a coating made of polyurethane with ceramics particles;

- if the textile substrate is used as an inner layer, firstly applying onto the substrate a coating made of polyurethane with ceramics particles, and secondly applying onto the substrate a coating made of polyurethane with aluminium particles;

- drying in an oven, preferably at 100 °C; and

- polymerising in an oven, preferably at 160 °C. The example of formulations used in the above process is as follows:

a) Aluminium compound:

- Water-based polyurethane polymer with 40% dry contents 100 parts

- Antifoaming agent 1 part

- Aluminium pigments

with 70% dry contents 10 parts

- Cross-linker 3.5 parts b) Ceramic compound:

- Water-based polyurethane polymer

with 40% dry contents 100 parts

- Antifoaming agent 1 part

- Ceramic blend

with 70% dry contents 10 parts

- Cross-linker 3.5 parts According to a second variation, the process f the first variation was used, this time based on foam compound.

In this second variation, the example of ormulations used is as follows:

a) Aluminium compound:

- Water-based polyurethane polymer

with 40% dry contents 100 parts

- Foaming agent (for example

sulphosuccinammate) 0.5 parts

- Foam stabilizer (ammonium stearate) 5 parts

- Ammoniac 5 parts

- Aluminium pigments with 70% dry contents 10 parts

- Cross-linker 3.5 parts b) Ceramic compound:

- Water-based polyurethane polymer

with 40% dry contents 100 parts

- Foaming agent (for example

sulphosuccinammate) 0.5 parts

- Foam stabilizer (ammonium stearate) 5 parts

- Ammoniac 5 parts

- Ceramic blend

with 70% dry contents 10 parts

- Cross-linker 3.5 parts

Finally, another embodiment of the inventive process comprises the steps of:

providing first thermoplastic polymers;

incorporating into the first thermoplastic polymers, some aluminium pigments made beforehand with a master batch;

providing second thermoplastic polymers;

incorporating into the second thermoplastic polymers, some ceramic pigments made beforehand with a master batch;

making a film using the first and second thermoplastic polymers, through an extrusion system;

heating granules of the first polymer blended with a master batch aluminium to reach their melting point;

- putting the melted compound in viscous form through a first lip, whose speed and shape affect the thickness of the layer of film; coating the film with a second layer of melted compound based on the second polymer blended with a master batch ceramic- putting the melted compound in viscous form through a second lip, whose speed and shape affect the thickness of the layer of film; melting together the two layers to form a two-layer film with one side containing aluminium and another side containing ceramics .

In this case, the extrusion system could be a flat (plane head) extrusion system, or a balloon extrusion system.

This process could also comprise the step of combining the two-layer film with a textile substrate .

In the above process, the polymer could be polyurethane, polyester, Ethylene Vinyl Acetate (EVA) or all kinds of thermoplastic polymers.

This two-layer film can be combined in a second stage with a woven or non-woven textile.

Other variations of the inventive process are possible, by mutually combining the above-described embodiments.