Elastic, breathable and waterproof film, particularly for applications in the medical field, and method for manufacturing such a film.

Abstract

- Elastic, breathable and waterproof film, in particular for applications in the medical field, and method for manufacturing such a film. - The method for manufacturing an elastic, breathable and waterproof film (1) comprises a main coating step, implemented by a coating device, consisting of coating one face (2A) of a non-woven fabric (2) with a polyurethane formulation (4), with an adaptation of at least one characteristic of the non-woven fabric (2) and / or at least one characteristic of the polyurethane formulation (4), so as to allow the polyurethane formulation (4), while forming a polyurethane layer (3) on said face (2A) of the non-woven fabric (2), to partially penetrate into the non-woven fabric (2) without passing through it completely, which makes it possible to obtain a film (1) having advantageous properties in terms of handling, porosity, breathability and watertightness. Figure for abstract: Fig. 1

Description

Title of the invention: Elastic, breathable and waterproof film, in particular for applications in the medical field, and method for manufacturing such a film. Technical field

[0001] The present invention relates to an elastic, breathable and waterproof film, in particular for applications in the medical field, as well as to a method for manufacturing such a film. State of the art

[0002] Although not exclusively, the film as considered in the present invention can be used more particularly as a support in various medical applications, such as dressings for wound care or covering patches for example. Applications can also be cited for complexes with very fluid, low-adhesive silicone-type formulations, which require direct coating on the film face of the complex.

[0003] To be able to be used in such applications, this film must have various properties and in particular be elastic, breathable (to water vapor) and impermeable (to water in particular).

[0004] Also, there is an interest and a need to produce a film having such properties. Statement of the invention

[0005] The object of the present invention is to provide an elastic, breathable and waterproof film, capable of being used in particular in the aforementioned applications and of meeting this need.

[0006] According to the invention, said film comprises a non-woven fabric provided on one side with a polyurethane layer, the material of which partially penetrates into said non-woven fabric without passing through it completely.

[0007] Thus, thanks to the invention, a film is obtained which has advantageous characteristics in terms of handling, porosity, sealing and breathability to water, as specified below. In particular, this film has unique mechanical properties, combining elasticity, breathability to water vapor, and impermeability to liquids and in particular to water. More precisely: - it is elastic, thanks in particular to the balance between the characteristics of the polyurethane layer and the non-woven fabric, as well as the partial presence of polyurethane in the thickness of the non-woven fabric; - it is breathable, thanks in particular to the chemical nature of the polyurethane polymer and to the thickness of the layer (polyurethane) deposited; - it is waterproof, thanks in particular to the continuous polyurethane layer present on the surface of one of the faces of the non-woven fabric; and - it is easy to handle so that it can be applied and removed easily without breaking, thanks in particular to its Young's modulus characteristic.

[0008] Due to its advantageous properties, this film is particularly well suited for use in the medical field, in particular for dressings for wound care, for covering patches, or for use as a support for low-tack silicone-type formulations.

[0009] To obtain a film with a polyurethane solution which partially penetrates the nonwoven without passing through it completely, advantageously, the nonwoven has appropriate values ​​of thickness, grammage, hydrophobic character and / or permeability, as specified below. In addition, in addition or as a variant, to obtain this partial penetration of the polyurethane solution, advantageously, the polyurethane formulation used has appropriate values ​​of viscosity and / or dry extract, as specified below.

[0010] In a preferred embodiment, the film (elastic, breathable and waterproof) has at least some of the following characteristics: - a weight between 20 and 300 g / m2; - a breaking strength greater than 300 N / m in the longitudinal direction of the machine and greater than 200 N / m in the transverse direction of the machine; - an elongation at break greater than 2% in the longitudinal direction of the machine and greater than 2% in the transverse direction of the machine; - a Young's modulus in the transverse direction of the machine between 5 and 250 MPa; and - a water vapor transmission rate greater than 1000 g / m2 / 24h.

[0011] These characteristics allow the film to obtain the aforementioned properties.

[0012] Advantageously, the polyurethane layer is obtained from a polyurethane formulation comprising an aliphatic polyurethane polymer based on polyether / polyester or polyether alone, combined or not with a hexamethylene-based aliphatic diisocyanate prepolymer.

[0013] Furthermore, in a first embodiment, the nonwoven is made of polyurethane, while in a second embodiment, the nonwoven is made of polyethylene terephthalate.

[0014] Furthermore, advantageously, the film also comprises at least one layer of adhesive applied to at least one of the faces of the assembly formed from the non-woven fabric and the polyurethane layer.

[0015] The present invention also relates to a method of manufacturing a film elastic, breathable and waterproof.

[0016] According to the invention, said method comprises at least one main coating step, implemented by a coating device, consisting of coating one face of a non-woven fabric with a polyurethane formulation, with an adaptation of at least one characteristic of the polyurethane formulation and / or of at least one characteristic of the non-woven fabric, so as to allow the polyurethane formulation, while forming a layer of polyurethane on said face of the non-woven fabric, to partially penetrate into the non-woven fabric without passing through it completely.

[0017] Thus, by using a non-woven fabric and a polyurethane formulation of which one or more characteristics have been appropriately chosen, the method is able to produce a coating allowing the polyurethane formulation to partially penetrate the non-woven fabric without passing through it completely, which makes it possible to obtain a film having the desired properties, namely a film which is in particular elastic, breathable and waterproof.

[0018] Advantageously, the characteristic(s) of the nonwoven which are adapted comprise at least one of the following characteristics of the nonwoven: - the thickness; - the weight; - air permeability; - the water vapor transmission rate.

[0019] Preferably, the nonwoven has at least one of the following ranges of values, relating to these adapted characteristics: - a thickness between 0.09 and 0.18 mm; - a weight between 20 and 300 g / m2, and preferably between 30 and 50 g / m2; - air permeability between 50 and 2000 L / m2 / s; and - a water vapor transmission rate greater than 3000 g / m2 / 24h.

[0020] Furthermore, advantageously, the characteristic(s) of the polyurethane formulation which are suitable comprise at least one of the following characteristics of the polyurethane formulation: - viscosity; - the dry extract.

[0021] Preferably, the polyurethane formulation has at least one of the following ranges of values, relating to these adapted characteristics: - a viscosity between 1000 and 2000 mPa.s; and - a dry extract between 58 and 62%.

[0022] In a preferred embodiment: - to obtain the polyurethane layer, the process uses a dispersion of aliphatic polyurethane polymer based on polyether / polyester or polyether alone, combined with a hexamethylene-based aliphatic diisocyanate crosslinker; and / or - the process uses a non-woven fabric which is made from one of the following materials: polyurethane, polyethylene terephthalate.

[0023] In one embodiment, the method also comprises an auxiliary coating step, implemented after the main coating step, consisting of depositing at least one layer of adhesive on at least one of the faces of the assembly formed from the non-woven fabric and the polyurethane layer.

[0024] Preferably, the coating device is configured to implement at least the main coating step via one of the following coating types: - an etching coating; - a spiral applicator coating; - a coating by transfer roller; - coating by flat die nozzle. Brief description of the figures

[0025] Other advantages and characteristics will emerge more clearly from the following description of several embodiments, given as non-limiting examples, of a film in accordance with the invention and its manufacturing method, with particular reference to the appended figures. In these figures, identical references designate similar elements.

[0026] [Fig.l] is a partial schematic view, in section, of an elastic, breathable and waterproof film, in accordance with one embodiment of the invention.

[0027] [Fig.2] is a schematic view of a first embodiment of a coating device forming part of a device for manufacturing an elastic, breathable and waterproof film.

[0028] [Fig. 3] is a schematic view of a second embodiment of a coating device forming part of a device for manufacturing an elastic, breathable and waterproof film.

[0029] [Fig.4] is a schematic view of a third embodiment of a coating device forming part of a device for manufacturing an elastic, breathable and waterproof film.

[0030] [Fig.5] is a schematic view of a fourth embodiment of a coating device forming part of a device for manufacturing an elastic, breathable and waterproof film. Detailed description

[0031] The film 1 used to illustrate the invention and partially shown according to a particular embodiment in [Fig.l] is an elastic, breathable and waterproof film, as specified below.

[0032] In the embodiment shown in [Fig.l], the film 1 comprises a non-woven fabric 2 provided on one 2A of its faces 2A and 2B (opposite), with a layer 3 of polyurethane, the material of which (i.e. the polyurethane formulation 4) has penetrated, from this face 2A into said non-woven fabric 2. In the context of the present invention, a part of the polyurethane formulation 4 is partially integrated into the non-woven fabric 2 (provided with fibers 5 shown very schematically in [Fig.l]), without passing through it completely.

[0033] The polyurethane formulation 4 is schematically represented by black dots in [Fig.l], with dots becoming smaller towards the inside of the layer 3 to illustrate that the concentration of the polyurethane formulation 4 decreases towards the inside of the layer 3 from the face 2A of the nonwoven 2. The layer 3 has two faces 3A and 3B (opposite), of which the face 3B is in contact with the face 2A of the nonwoven 2.

[0034] In the context of the present invention, an adaptation of at least one characteristic of the polyurethane formulation 4 used and / or an adaptation of at least one characteristic of the non-woven fabric 2 used is provided, so as to allow the polyurethane formulation 4 which forms the polyurethane layer 3 to penetrate into a part of the non-woven fabric 2 (in the direction illustrated by arrows G) without completely crossing the thickness E of the non-woven fabric 2, as illustrated by the black dots in [Fig.l].

[0035] The non-woven fabric 2 therefore has one or more particular characteristics, depending on the embodiment envisaged, which allow the polyurethane formulation 4 to penetrate into it without passing through it.

[0036] In particular to obtain this partial penetration into the non-woven fabric 2, at least some (and preferably all) of the following characteristics must be taken into account when choosing the non-woven fabric 2: - the thickness E ([Fig.l]) of the non-woven fabric 2; - the weight of the non-woven fabric 2; - the hydrophobic character of the non-woven fabric 2, obtained by its chemical formulation and / or from an appropriate treatment; - the air permeability of the non-woven fabric 2.

[0037] In a preferred embodiment, for the film 1 to obtain the desired properties, at least some of these characteristics of the nonwoven 2 have the following values: - a thickness between 0.09 and 0.18 mm; - a weight between 20 and 300 g / m2, and preferably between 30 and 50 g / m2; and - an air permeability between 50 and 2000 L / m2 / s.

[0038] In the context of the present invention, the ranges of values ​​presented in the form of "between x and y" include the limits x and y, the integers included between these limits, as well as all other real numbers between these limits.

[0039] Preferably, the non-woven fabric 2 used also has: - a water vapor transmission rate greater than 3000 g / m2 / 24h; - a breaking strength greater than 300 N / m in the longitudinal direction of the machine (hereinafter MD for “machine direction” in English) and greater than 250 N / m in the transverse direction of the machine (hereinafter CD for “cross direction” in English); and - an elongation at break greater than 2% in the longitudinal direction of the machine and greater than 7% in the transverse direction of the machine.

[0040] The non-woven fabric 2 can be produced in different ways.

[0041] In a first embodiment, the non-woven fabric 2 is made of polyurethane.

[0042] Furthermore, in a second embodiment, the nonwoven 2 is made of polyethylene terephthalate (PET).

[0043] By way of illustration, the table below highlights the main characteristics of the nonwoven 2 for five different nonwovens named NT1 to NT5, which are likely to be used to produce the film 1: Commercial references NT1: BR7398-050 NT2: BR6331-034 NT3: BR7396-045 NT4: BR7378-04 0 NT5: 1EM045A7 5T Manufacturing technology “Wetlaid” “Wetlaid” “Wetlaid” “Wetlaid” “Meltblow n” Nature of fibers Cellulose / PET Cellulose / PET Cellulose / PET Cellulose / PET TPU Treatment Fluorocarbon None Non-fluorinated treatment Non-fluorinated treatment None Weight (g / m2) 45 34 45 40 45 Thickness (W 124 95 108 108 170 Permeability (L / m2 / s) 320 1445 98 650 750 Water drop test (s) 999 >999 - 999 - Test of the >540 354 540 >540 - drop of alcohol (s) Breaking strength (N / m) MD: 1960 CD: 1100 MD: 774 CD: 619 MD: 2795 CD: 755 MD: 1450 CD: 820 MD: 440 CD: 300 Elongation at break W MD: 5.3 CD: 12.9 MD: 18.5 CD: 24.7 MD: 2.9 CD: 9.8 MD: 6.0 CD: 13.0 MD: 230 CD: 220 Water vapor breathability (g / m2 / 24h) 5330 5425 4715 5395 6030

[0044] This table shows for the five examples of non-woven NT1 to NT5 considered: - their commercial reference; - the manufacturing technology used; - the nature of the non-woven fibers; - possible treatment; - the weight in g / m2 (FTM12); - the thickness in pm (NF in ISO 534); - air permeability in L / m2 / s (WSP 70.1); - a water drop test in seconds; - an alcohol drop test in seconds; - breaking strength in N / m (measured according to standard NF EN 29073-3); - the elongation at break in % (measured according to standard NF EN 29073-3); and - the water vapor transmission rate in g / m2 / 24h (NF EN 13726-2).

[0045] For these five examples of nonwovens NT1 to NT5, the values ​​of grammage, thickness, breaking strength and elongation at break are included in the ranges of values ​​sought for nonwoven 2, as indicated above.

[0046] Furthermore, in addition to or as a variant of the aforementioned particular characteristics of the non-woven fabric 2, in order to allow the polyurethane formulation 4 to penetrate into the non-woven fabric 2, without passing through it completely, at least one of the following characteristics must be taken into account for the choice of the polyurethane formulation 4: - its viscosity; and - its dry extract.

[0047] Adjusting the viscosity makes it possible to avoid bleed-through during coating, while controlling the weight deposited.

[0048] In a preferred embodiment, to obtain the aforementioned desired objective, the polyurethane formulation 4 has at least one of the following characteristics: - a viscosity (measured at 25°C, speed 2 according to standard NF EN ISO 2555) between 1000 and 2000 mPa.s; and - a dry extract between 58 and 62%.

[0049] Further, in a preferred embodiment, the polyurethane formulation (named UE-12) that may be used comprises the following components: - an aliphatic polyurethane polymer based on polyether / polyester, for 100 parts; and - an aliphatic diisocyanate prepolymer based on hexamethylene (HDI), for 3 parts (crosslinking agent).

[0050] The use of the crosslinker results in a lifetime of the mixture of the order of 6 hours.

[0051] Furthermore, the film 1 may also comprise at least one layer of adhesive.

[0052] In a first embodiment, the film 1 comprises two layers of adhesive 7A and 7B applied, respectively, to the face 3A of the polyurethane layer 3 and to the face 2B of the non-woven fabric 2, as shown in [Fig.l].

[0053] In a second embodiment, the film 1 comprises a single layer of adhesive applied to one of the faces of the assembly 6 formed from the non-woven fabric 2 and the polyurethane layer 3. In this first embodiment, the adhesive layer can be applied to the face 2B of the non-woven fabric 2, like the adhesive layer 7B of [Fig. 1] or to the face 3A of the polyurethane layer 3, like the adhesive layer 7A of [Fig. 1].

[0054] The adhesive film 1 thus obtained can be easily glued, and this by one of its faces or by its two faces depending on the embodiment used, in particular depending on the application envisaged.

[0055] The film 1, as described above, is obtained using a manufacturing method specified below. This manufacturing method comprises, in particular, a particular main coating step.

[0056] This main coating step, which is implemented by a coating device, consists of coating a face 2A of a non-woven fabric 2 with a polyurethane formulation 4, with an adaptation of at least one characteristic of the polyurethane formulation 4 and / or of at least one characteristic of the non-woven fabric 2, so as to allow the polyurethane formulation 4, while forming a layer 3 of polyurethane on said face 2A of the non-woven fabric 2, to partially penetrate into the non-woven fabric 2 (in the direction illustrated by the arrows G in [Fig.l]), without passing through it completely.

[0057] The polyurethane formulation 4 making it possible to obtain layer 3 corresponds to a dispersion of aliphatic polyurethane polymer based on polyether / polyester, combined with an aliphatic isocyanate crosslinker of the HDI type (hexamethylene diisocyanate).

[0058] The method therefore makes it possible to produce a complex (film 1) comprising a non-woven fabric 2, in particular made of polyurethane, covered with a layer 3 of polyurethane. The non-woven fabric 2 can be of variable color (white, flesh, brown, etc.) depending on the intended application.

[0059] In the context of the present invention, the method, and in particular its coating step, can be implemented using different coating devices such as, for example, those described below, by way of illustration, with reference to FIGS. 2 to 5.

[0060] In a first embodiment shown in [Fig.2], the manufacturing method uses a coating device 8A configured to implement etching coating.

[0061] In this first embodiment, the coating device 8A comprises a reservoir 9 containing the polyurethane formulation 4 and a rotating engraved cylinder (or roller) 10, provided with an engraved external surface 11 (with asperities and / or recesses). The engraved cylinder 10 is arranged so that a lower part 10A of said engraved cylinder 10 is immersed in the polyurethane formulation 4.

[0062] By rotating, in the direction illustrated by arrows F1, the engraved cylinder 10 carries away with its external surface 11 engraved with the polyurethane formulation 4. The excess (or surplus) of polyurethane formulation 4 is removed by passing and in contact with a scraper 12.

[0063] In addition, the non-woven fabric 2 to be coated with the polyurethane formulation 4 is pressed by a rotating pressure cylinder (or roller) 13 against an upper part 10B of the engraved cylinder 10. This pressure cylinder 13 rotates in the direction illustrated by arrows F2, namely in the opposite direction to the direction F1 of rotation of the engraved cylinder 10. By rotating in the directions, respectively, of the arrows F1 and F2, the engraved cylinder 10 and the pressure cylinder 13 participate in the movement of the non-woven fabric 2 in the direction illustrated by an arrow II in [Fig. 2]. During this movement, the polyurethane formulation 4 which is brought from the reservoir 9 by the engraved cylinder 10 is deposited on the face 2A of the non-woven fabric 2, coming into contact with the engraved cylinder 10, at a contact zone (at the upper part 10B). The polyurethane formulation 4 then partially penetrates the non-woven fabric 2 without passing through it.

[0064] Downstream of this contact zone, the non-woven fabric 2 is therefore coated with the polyurethane formulation 4, which makes it possible to obtain the film 1.

[0065] In a second embodiment shown in [Fig.3], the manufacturing method uses a coating device 8B configured to implement a spiral applicator coating (or “Meyer bar coating” in English).

[0066] In this second embodiment, the coating device 8B comprises a reservoir 14 containing the polyurethane formulation 4 and a rotating applicator cylinder (or roller) 15, provided with a non-smooth external surface 15C. The applicator cylinder 15 is arranged so that a lower part 15A of said applicator cylinder 15 is immersed in the polyurethane formulation 4.

[0067] By rotating, in the direction illustrated by arrows F3, the applicator cylinder 15 carries with its external surface 15C of the polyurethane formulation 4 and deposits it on the face 2A of the non-woven fabric 2, in contact with an upper part 15B of the applicator cylinder 15, at a contact zone. Downstream of this contact zone, in the direction of movement 12 of the non-woven fabric 2, a spiral applicator 16 (“Meyer Bar”) is arranged which removes the excess polyurethane formulation 4 to obtain the desired thickness of the polyurethane layer 3. The polyurethane formulation 4 then penetrates partly into the non-woven fabric 2 without passing through it.

[0068] Downstream of the spiral applicator 16, the non-woven fabric 2 is therefore coated with the polyurethane formulation 4, which makes it possible to obtain the film 1. In the embodiment shown in [Fig.3], the coating device 8B also comprises an auxiliary roller 17 for bringing the film 1 in a desired direction.

[0069] Furthermore, in a third embodiment shown in [Fig.4], the manufacturing method uses an 8C coating device configured to implement a transfer roller coating (or “kiss coating” in English).

[0070] In this third embodiment, the coating device 8C comprises a reservoir 18 containing the polyurethane formulation 4 and a rotating applicator cylinder (or roller) 19, provided with a non-smooth external surface 19C. The applicator cylinder 19 is arranged so that a lower part 19A of said applicator cylinder 19 is immersed in the polyurethane formulation 4.

[0071] By rotating, in the direction illustrated by arrows F4, the applicator cylinder 19 carries with its external surface 19C the polyurethane formulation 4 in order to deposit it on the face 2A of the non-woven fabric 2, in contact with an upper part 19B of the applicator cylinder 19, at a contact zone. At the outlet of the applicator cylinder 19 from the reservoir 18, a blade 20 is arranged which scrapes off the excess polyurethane formulation 4.

[0072] In addition, the non-woven fabric 2 to be coated with the polyurethane formulation 4 is pressed by a rotating pressure cylinder (or roller) 21 against the upper part 19B of the applicator cylinder 19. This pressure cylinder 21 rotates in the direction illustrated by arrows F5, namely in the opposite direction to that (arrows F4) of the applicator cylinder 19. By rotating in the directions, respectively, of the arrows F4 and F5, the applicator cylinder 19 and the pressure cylinder 21 participate in the movement of the non-woven fabric 2 in the direction illustrated by an arrow 13 in [Fig.4]. During this movement, the polyurethane formulation 4 is deposited on the face 2A of the non-woven fabric 2, coming into contact with the applicator cylinder 19, at a contact zone (at the level of the upper part 19B). The polyurethane formulation 4 then partially penetrates into the non-woven fabric 2 without passing through it.

[0073] Downstream of this contact zone, the non-woven fabric 2 is therefore coated with the polyurethane formulation 4, which makes it possible to obtain the film 1.

[0074] The quantity of coating deposited (namely the polyurethane formulation 4 deposited) depends in particular on the coating speed, the rotation speed of the applicator cylinder 19, the contact pressure generated by the pressure cylinder 21, the viscosity of the polyurethane formulation 4 and the characteristics of the blade 20.

[0075] In a fourth embodiment shown in [Fig.5], the manufacturing method uses an 8D coating device configured to implement slot die coating.

[0076] In this fourth embodiment, the coating device 8D comprises a die 22 provided with a slot 23, configured to distribute the polyurethane formulation 4.

[0077] The coating device 8D also comprises a cylinder 24 intended for moving the non-woven fabric 2. This cylinder 24 rotates in the direction illustrated by arrows F6, to participate in moving the non-woven fabric 2 in the direction shown by an arrow 14. The non-woven fabric 2 is moved under the die 22. The polyurethane formulation 4 is deposited on the face 2A of the non-woven fabric 2, at a coating zone 25 located directly under the die 22. The polyurethane formulation 4 then partially penetrates the non-woven fabric 2 without passing through it.

[0078] Downstream of this coating zone, the non-woven fabric 2 is therefore coated with the polyurethane formulation 4, which makes it possible to obtain the film 1.

[0079] The 8D coating device makes it possible, in particular, to properly control the thickness of the deposited polyurethane formulation 4.

[0080] The coating devices 8A, 8B, 8C and 8D described above make it possible to produce a coating, in large width, of a thin layer 3 of a polyurethane formulation 4 on a non-woven fabric 2, without causing the formulation to pass through to the heart of the fibers 5 of the non-woven fabric 2.

[0081] Whatever the coating device 8A, 8B, 8C and 8D used, the manufacturing method takes into account the characteristics (such as thickness, grammage, hydrophobic character, permeability) specified above for the non-woven 2 and the characteristics specified above (such as viscosity and dry extract) for the polyurethane formulation 4.

[0082] In a preferred embodiment, to obtain the polyurethane layer 3, the method uses, as polyurethane formulation 4, a dispersion of poly polymer aliphatic urethane based on polyether / polyester 4, combined with an aliphatic isocyanate crosslinker of the HDI type (hexamethylene diisocyanate).

[0083] The characteristics (viscosity, rheology) of the polyurethane formulation 4 without aggressive solvent make it possible to manufacture a complex (film 1) in line without an interface between the non-woven 2 and the layer 3. This complex thus has interesting characteristics in terms of handling, porosity, breathability and watertightness.

[0084] Furthermore, in a preferred embodiment, the manufacturing method uses a nonwoven 2 which is made of one of the following materials: polyurethane, polyethylene terephthalate.

[0085] Furthermore, in a particular embodiment, the manufacturing method further comprises an auxiliary coating step implemented by a conventional auxiliary coating device, after the main coating step specified above. The auxiliary coating device (not shown) applies, in the usual manner, to at least one of the faces 2B and 3A of the assembly 6 ([Fig.l]) a layer of adhesive, such as the adhesive layer 7A or the adhesive layer 7B of [Fig.l]. The adhesive film 1 thus obtained can then be easily bonded to a support of the intended application.

[0086] The table below highlights the main characteristics of the film 1, preferably obtained from one of the aforementioned manufacturing and coating processes, for four examples 1A, 1B, 1C and 1D of film. Film IA IB IC 1D Construction UE-12onNT5 UE-12 on NT 1 UE-12 on NT3 UE-12 on NT4 Basis of deposited polyurethane formulation (g / m2) 30 25 25 25 Tensile strength (N / cm) MD: 4.7 - 10.7 CD: 2.4 - 8.4 MD: 18.4 CD: 13.0 MD: 29.9 CD: 8.5 MD: 13.7 CD: 9.5 Elongation at break W MD: 220-360 CD: 170-310 MD: 6.2 CD: 13.4 MD: 3.2 CD: 12.0 MD: 7.3 CD: 16.3 Young's modulus in transverse direction 11.4 243 203 163 (MPa) MVTR (g / m2 / 24h) >1400 >2000 >1800 >1800

[0087] This table presents for the four examples IA, IB, IC and 1D considered from film 1: - their construction, namely the non-woven fabric used (in this case the NT1 to NT5 non-woven fabrics specified above) associated with the same polyurethane formulation (EU-12); - the weight of the polyurethane formulation deposited in g / m2 (FTM12); - breaking strength in N / m (measured according to standard NF EN 29073-3); - elongation at break in % (measured according to standard NF EN 29073-3); - Young's modulus in MPa (measured according to the NF EN 29073-3 method); - the moisture vapor transmission rate (MVTR), namely the rate of water permeation through a membrane, measured (according to standard NF EN 13726-2) in mass per unit of surface area per unit of time, in this case in g / m2 / 24h.

[0088] This table makes it possible to highlight the following advantageous characteristics sought for film 1, which are present in each of the four examples IA, IB, IC and 1D considered: - a weight between 20 and 300 g / m2; - a breaking strength greater than 300 N / m in the longitudinal direction of the machine and greater than 200 N / m in the transverse direction of the machine; - an elongation at break greater than 2% in the longitudinal direction of the machine and greater than 2% in the transverse direction of the machine; - a Young's modulus (or transverse modulus of elasticity) between 5 and 250 MPa; and - a water vapor transmission rate greater than 1000 g / m2 / 24h.

[0089] The characteristics of the association between the non-woven fabric and the polyurethane formulation make the film 1 flexible and easy to handle, and in particular sufficiently easy to handle for the intended applications.

[0090] Therefore: - the film 1 (final complex) obtained retains its permeability to water vapor, thanks to the coating of a breathable polyurethane formulation 4; and - the mechanical characteristics of the film 1 obtained vary depending on the nature of the non-woven fabric 2 used. Also, an appropriate choice of the non-woven fabric 2 makes it possible to obtain one or more desired mechanical characteristics, in particular depending on the intended application.

[0091] Film 1, as described above, is particularly well suited for use as a dressing or covering patch in the medical field. Indeed, this film 1 is: - elastic and conformable, and therefore comfortable to wear; - lightly embossed on the surface so as to be soft to the touch and limit friction; - breathable so as to allow the passage of water vapor to the surface of the skin and ensure perfect adhesion throughout the intended period of use; and - waterproof so as to increase the duration of application on the skin.

[0092] The film 1, as described above, can be used in many other applications, in particular (but not exclusively) in the medical sector. More generally, the film 1 can be used in all applications in which its advantageous characteristics (and in particular its unique mechanical properties, combining elasticity, breathability to water vapor and impermeability to water) are sought.

[0093] It is obvious that the examples presented above are only particular illustrations, in no way limiting as to the fields of application of the present invention. In addition, features of some of these different examples can be combined with each other if appropriate, without departing from the scope of the present invention.

Claims

Claims

1. Elastic, breathable and waterproof film, characterized in that it comprises a non-woven fabric (2) provided on one face (2A) with a layer (3) of polyurethane, the material (4) of which partially penetrates into said non-woven fabric (2) without passing through it completely.

2. Film according to claim 1, characterized in that said film (1) has at least some of the following characteristics: - a grammage of between 20 and 300 g / m2; - a breaking strength greater than 300 N / m in the longitudinal direction of the machine and greater than 200 N / m in the transverse direction of the machine; - an elongation at break greater than 2% in the longitudinal direction of the machine and greater than 2% in the transverse direction of the machine; - a Young's modulus in the transverse direction of the machine of between 5 and 250 MPa; and - a water vapor transmission rate greater than 1000 g / m2 / 24h.

3. Film according to one of claims 1 and 2, characterized in that the polyurethane layer (3) is obtained from a polyurethane formulation (4) comprising an aliphatic polyurethane polymer based on polyether / polyester or polyether alone and an aliphatic diisocyanate prepolymer based on hexamethylene.

4. Film according to one of claims 1 to 3, characterized in that the non-woven fabric (2) is made of polyurethane.

5. Film according to one of claims 1 to 3, characterized in that the non-woven fabric (2) is made of polyethylene terephthalate.

6. Film according to any one of the preceding claims, characterized in that it comprises at least one layer of adhesive (7A, 7B) applied to at least one of the faces (2B, 3A) of the assembly (6) formed from the non-woven (2) and the polyurethane layer (3).

7. Method for manufacturing an elastic, breathable and waterproof film, characterized in that it comprises at least one main coating step, implemented by a coating device (8A, 8B, 8C, 8D), consisting of coating one face (2A) of a non-woven fabric (2) with a polyurethane formulation (4), with an adaptation of at least one characteristic- characteristic of the nonwoven (2) and / or at least one characteristic of the polyurethane formulation (4), so as to allow the polyurethane formulation (4), while forming a polyurethane layer (3) on said face (2A) of the nonwoven (2), to partially penetrate into the nonwoven (2) without passing through it completely.

8. Method according to claim 7, characterized in that the characteristic or characteristics of the nonwoven (2) which are adapted comprise at least one of the following characteristics of the nonwoven (2): - the thickness; - the grammage; - the air permeability; - the water vapor transmission rate.

9. Method according to claim 8, characterized in that the nonwoven (2) has at least one of the following ranges of values: - a thickness between 0.09 and 0.18 mm; - a weight between 20 and 300 g / m2; - an air permeability between 50 and 2000 L / m2 / s; and - a water vapor transmission rate greater than 3000 g / m2 / 24h.

10. Method according to one of claims 7 to 9, characterized in that the characteristic or characteristics of the polyurethane formulation (4) which are adapted comprise at least one of the following characteristics of the polyurethane formulation (4): - the viscosity; - the dry extract.

11. Method according to claim 10, characterized in that the polyurethane formulation (4) has at least one of the following ranges of values: - a viscosity of between 1000 and 2000 mPa.s; and - a dry extract of between 58 and 62%.

12. Method according to any one of claims 7 to 11, characterized in that it comprises an auxiliary coating step, consisting of depositing at least one layer of adhesive (7A, 7B) on at least one of the faces (2B, 3A) of the assembly (6) formed from the non-woven (2) and the polyurethane layer (3).

13. Method according to any one of claims 7 to 12, characterized in that the coating device (8A, 8B, 8C, 8D) is configured to implement at least the main coating step via one of the following coating types: - an etching coating; - a spiral applicator coating; - a coating by transfer roller; - coating by flat die nozzle.

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