Single-layer monolithic waterproof and breathable film

Abstract

1) A single-layer monolithic waterproof and breathable film A consisting of at least 50% by weight of a highly breathable polymer and having a thickness between 5 and 150 μm, characterized in that one of its surfaces exhibits an arithmetic mean roughness Ra of at least 0.1 μm. 2) A method for producing the film, - forming by coextrusion a multilayer film M comprising two layers B / A, Layer A is as defined above, Layer B is a peelable layer having a thickness between 15 and 100 μm and consisting of a dispersion of high density polyethylene (HDPE) in a continuous phase of atactic polypropylene (PP), the amount of dispersed HDPE being such that Layer B exhibits an arithmetic mean surface roughness Ra of at least 0.1 μm; forming a multilayer film M; (ii) separating the monolayer film A by peeling off the layer B of the multilayer film M; A manufacturing method comprising:

Description

[Technical Field]

[0001] The subject of the present invention is a single-layer monolithic waterproof and breathable film, a method suitable for producing said film by coextrusion, and a composite product (or laminate) comprising said film. [Background technology]

[0002] Waterproof breathable films (also called "breathable films") are widely used in the manufacture of articles in various fields, such as in the clothing sector, in particular sportswear or surgical protective clothing, and personal protective equipment, and in the construction sector, in particular for under-roof insulation in dwellings.

[0003] In these various fields, it is important to have available barrier films, especially films that are waterproof and breathable yet permeable to water vapor, to provide protection from liquids, especially water.

[0004] For example, in the case of sportswear such as hiking outerwear, it is important to protect the hiker from rain while promoting breathability to allow evaporation of sweat and ensure the hiker's comfort. It is also desirable to ensure this same comfort for surgeons, nurses, and even patients, who must be protected from any contact with bodily fluids, infectious agents, or chemicals during surgical procedures. Among the corresponding protective clothing are the gowns worn by surgeons and nurses, and the surgical drapes worn by patients during surgery.

[0005] Among waterproof and breathable films, monolithic waterproof and breathable films, which are continuous films substantially free of pores, are known. Such films are advantageous over microporous waterproof and breathable films in that their barrier properties against liquids, particularly water, do not depend on surface tension. Monolithic waterproof and breathable films also exhibit better barrier effects against viruses and odors and maintain better breathability over time.

[0006] Waterproof and breathable films are generally obtained by molding highly breathable polymers. Highly breathable polymers are permeable to water vapor and substantially impermeable to liquid water, making them suitable for obtaining waterproof and breathable films. More specifically, the term "highly breathable polymer" refers to a polymer that, when formed into a film having a thickness of 15 μm, has a high moisture vapor transmission rate (i.e., MVTR), more specifically, at least 1000 g / m 2 / day, preferably at least 1500g / m 2 The term "MVTR" is intended to refer to thermoplastic polymers that exhibit a moisture vapor transmission rate of 1000 psi / day. MVTR is measured according to ASTM E96B standard at 38°C and 50% relative humidity.

[0007] Highly breathable polymers include, for example: copolymers containing polyamide and polyether blocks (hereinafter referred to as TPA), such as Pebax® from the Arkema group; copoly(ether-urethane) or thermoplastic polyurethanes (hereinafter referred to as TPU), such as Estane® from the Lubrizol group, and Copoly(ester-ether) or thermoplastic elastomeric copolyesters (hereinafter referred to as TPC), such as Arnitel® from DSM or Hytrel® from DuPont. The thermoplastic elastomer polymer (hereinafter referred to as TPE) is selected from the following:

[0008] These thermoplastic elastomeric polymers are available in the form of granules that are converted into films by specialized converters.

[0009] These waterproof, breathable films are generally used to form laminated (or composite) products by attaching them to at least one porous support layer, which may consist of a woven or nonwoven fibrous material. Such laminates are used for the manufacture of the aforementioned articles, such as sportswear, or for the manufacture of specific parts of said articles. These laminated products are obtained by laminating (or composite) a single-layer breathable film onto a fibrous support layer using discontinuous or continuous application of an adhesive, such as a hot melt adhesive.

[0010] Such adhesive bonding operations are generally carried out by laminating specialists (often called laminators) on machines operating continuously at high line speeds, and both the individual layers and the final laminated product are so large in size that they are wound and packaged in wide reels up to about 3 m in width (or machine width) and up to about 1 m in diameter.

[0011] Therefore, in view of these lamination operations, it is necessary to have available waterproof, breathable films that are wound and packaged in the form of such reels.

[0012] However, both when producing such films on a converting machine to obtain such web products and when used in subsequent lamination operations, a problem known as "blocking" can be encountered.

[0013] The term "blocking" refers to the difficulty, and sometimes the impossibility, of winding a film onto a reel or unwinding a film thus wound, under line speed conditions suitable for industrial production. The difficulty is due to speed non-uniformities of the reels involved, which can even lead to jerks, creating significant tension forces in the film that can even lead to film breakage.

[0014] Such problems are generally due to the residual tack exhibited by the film's surfaces, which is expressed as resistance (or friction) to relative sliding motion between the two surfaces of the film that are in contact during winding or unwinding of the reel, which friction can be quantified by the coefficient of friction.

[0015] From the application of Polymer Group, WO 2016 / 100699, a multilayer waterproof and breathable film is known, which comprises a monolithic central layer comprising a highly breathable polymer and two outer layers adjacent to each of the two sides of the central layer, which outer layers necessarily comprise, in addition to the highly breathable polymer and the non-breathable material, a filler in the form of particles or particle agglomerates.

[0016] The particles have a median diameter greater than the thickness of the outer layers, and therefore form non-peelable protrusions (or projections) on the free surface of each of the outer layers.

[0017] This multilayer waterproof and breathable film advantageously exhibits a reduced tendency to block when wound onto a reel, as quantified by a low coefficient of friction. The film can be made by a flat coextrusion process, which includes treatment with specific rollers that can impart a matte appearance.

[0018] However, when a filler is used in the outer layer, the breathability tends to decrease.

[0019] The prior art also knows monolithic, single-layer waterproof and breathable films A1, the thickness of which ranges from 8 to 60 μm and which consist of a composition (a1) itself consisting of at least 50% by weight of one or more highly breathable polymers and up to 50% by weight of various additives.

[0020] The film is - forming by coextrusion a multilayer film F1 consisting of two layers B1 / A1 or three layers B1 / A1 / C1, in which layers B1 and C1 are each peelable layers with a thickness in the range of 15 to 100 μm and consisting of compositions (b1) and (c1) of low density polyethylene (LDPE), respectively; - separating layer A1 by simply peeling off layer B1 and, if present, layer C1; It is produced by a method comprising:

[0021] In describing multilayer films, the symbol " / " used above will be clearly understood from the constituent layers to mean that the faces of the layers involved are in direct contact, and the same is true for all multilayer structures described herein unless specifically stated to the contrary.

[0022] The process is carried out by co-extrusion using inflation molding, which process comprises: - introducing compositions (a1), (b1) and optionally (c1) in the form of granules having a size between 1 and 10 mm into separate extruders, - converting said granules into a molten state by heating, and then - passing each corresponding stream through an extrusion head equipped with a pair of coplanar and concentric annular dies (this head is brought to a temperature in the range of 150°C to 260°C so as to form, by injection of pressurized air, a cylindrical tubular bubble (or sheath) with several layers, the order of the layers corresponding to that desired in the final film, with layer A1 being on the outside of the tubular sheath in the case of a two-layer B1 / A1), then - expanding the bubble radially (relative to the plane of the annular die) and stretching (perpendicular to said plane), then cooling said bubble Includes.

[0023] The cylindrical bubble thus formed is generally further flattened by passing it between two nipper rolls and then cut near its two edges into two separate films which are then individually packaged in the form of rolls around reels.

[0024] In this known embodiment of the prior art, the support layers B1 and C1, often consisting essentially of LDPE, have the function of maintaining the stability of the tubular bubble during the process, thereby facilitating the molding of the highly breathable polymer to obtain a monolithic, single-layer, waterproof, breathable film (A1). According to a more specific embodiment of the prior art, the support layers B1 and C1 are identical and are called S1, so that the film F1 is a symmetrical three-layer S1 / A / S1.

[0025] Said layers (B1) and (C1), which are chemically incompatible with layer (A1), are intended to be removed during a subsequent peeling step (also called stripping) so that the laminator can perform the task of laminating a single, monolithic, single-layer waterproof and breathable film (A1) to the fibrous support layer.

[0026] However, according to this same embodiment of the prior art, the surface of the monolayer film A1 obtained after removing one or both of the outer layers B1 and C1 exhibits a tackiness at room temperature that tends to cause the film to stick to itself, which is manifested as a high coefficient of friction that results in the undesirable phenomenon of blocking. In contrast, no blocking is observed in the case of the two-layer film B1 / A1 or the three-layer film B1 / A1 / C1.

[0027] Thus, a processing machine producing a monolayer film A1 by molding a highly breathable polymer must package the film A1 together with at least one of two support layers B1 and C1 for delivery to a laminator. Therefore, the laminator must necessarily peel off the support layer present on the reel received from the processing machine before laminating the film A1 onto the fibrous support layer. The presence of the support layer complicates the laminator's process and also creates problems for the laminator due to the generation of waste from the peeled support layer and its reprocessing for recyclability.

[0028] Furthermore, the surface of the single-layer monolithic waterproof and breathable film A1 of this same prior art embodiment also exhibits a glossy appearance, which must be avoided in consideration of certain end uses. This is the case, for example, for waterproof and breathable films intended for the manufacture of gowns worn by surgeons and nurses during surgical procedures, due to the unpleasant reflections from the strong lighting in operating rooms. For such applications, a matte appearance on the surface of the single-layer breathable film is highly desirable. Summary of the Invention

[0029] It is an object of the present invention to provide a monolithic waterproof, breathable film that can be packaged without an outer layer and then used and wound onto a reel.

[0030] Another object of the present invention is to provide a monolithic waterproof, breathable film that when wound on a reel exhibits no or reduced blocking.

[0031] Another object of the present invention is to provide a monolithic waterproof, breathable film that exhibits a low coefficient of friction.

[0032] Another object of the present invention is to provide a monolithic waterproof, breathable film that retains its breathability, especially over time.

[0033] Another object of the present invention is to provide a monolithic waterproof breathable film that exhibits a matte appearance.

[0034] Another object of the present invention is to provide a monolithic waterproof, breathable film that can be produced by a coextrusion process that does not involve passing over a matte roller.

[0035] It has now been found that these objectives can be achieved in whole or in part by the monolithic waterproof and breathable film that is the subject of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] Single-layer monolithic waterproof and breathable film A Therefore, the present invention first relates to a single-layer monolithic waterproof and breathable film A having a thickness of between 5 and 150 μm and made of composition (a), wherein composition (a) contains at least 50 wt % of a highly breathable polymer based on the total weight of the composition, and the single-layer monolithic waterproof and breathable film A is characterized in that at least one of its two surfaces exhibits an arithmetic mean roughness Ra of at least 0.1 μm.

[0037] It has been found that the film advantageously exhibits a matte (i.e., non-glossy) appearance and can be packaged in the form of a roll onto a reel and then unwound under industrial line speed conditions without exhibiting blocking. The surface provided with the roughness defined above reduces the coefficient of friction, in particular during the relative sliding movement of said surface in contact with another surface. Finally, the film according to the invention exhibits breathability, quantified by MVTR measured on a film thickness of 15 μm according to ASTM E96B standard at 38° C. and 50% relative humidity, of at least 1000 g / m 2 / day, preferably at least 1500g / m 2 / day, more preferentially at least 2000g / m 2 / day, and preferentially at least 2500g / m 2 / day. Such monolithic waterproof and breathable films further exhibit advantages in terms of industrial logistics of single layers compared to prior art multilayer systems, both for processors of highly breathable polymers and laminators of said films.

[0038] The arithmetic mean roughness Ra is measured using a stylus profilometer. A stylus profilometer is an instrument with a very fine tip, often made of diamond, attached to a stylus, which reads the height of the stylus as it moves along the surface with a vertical accuracy that can reach 5 angstroms. It is used to measure surface relief, particularly for the purpose of assessing surface roughness or topography. It is therefore possible to measure the thickness of thin layers of tens of nanometers as easily as coatings of hundreds of micrometers. Such profilometers are commercially available, such as the Bruker Dektak XT profilometer.

[0039] The arithmetic mean roughness Ra represents the average difference between the peaks and valleys present on the measured surface. It is expressed in μm and is defined as the arithmetic mean deviation of the absolute values ​​of the ordinates (or heights) of the protrusions (or peaks) and valleys of the measured profile, according to the ISO 4287 standard of April 1997.

[0040] According to a preferred alternative form of the single-layer monolithic waterproof and breathable film according to the invention, at least one of its two faces exhibits an arithmetic mean roughness Ra of at least 0.3 μm, and even more preferably at least 0.5 μm.

[0041] According to an equally preferred embodiment, at least one of the two faces of the film according to the invention exhibits, in addition to the properties defined above for Ra, a number of peaks per unit length RPc of at least 40, preferably at least 50, and even more preferably at least 60. The number of peaks per unit length RPc is defined by the ISO 4287 standard of June 2009 and is also determined by measurements using a stylus profilometer.

[0042] According to one embodiment of the present invention, the arithmetic mean roughness Ra characteristic defined above is exhibited by each of the two faces of the film according to the invention.

[0043] According to a more preferred embodiment, the above-defined characteristic of the number of peaks RPc is also exhibited by each of the two faces of the film according to the invention.

[0044] In these last two embodiments, the film can be very easily wound and unwound on both sides in industrial units without the risk of blocking.

[0045] The single-layer monolithic waterproof and breathable film A according to the present invention generally has a thickness between 5 and 150 μm.

[0046] According to one embodiment, the thickness is in the range of 6 to 100 μm, preferably 8 to 50 μm, particularly preferably 8 to 30 μm.

[0047] Composition of Layer A (a) The composition (a) constituting the single-layer monolithic waterproof and breathable film A according to the present invention comprises at least 50% by weight of at least one highly breathable polymer, based on the total weight of the composition.

[0048] The highly breathable polymer is preferably a thermoplastic elastomeric polymer having a water vapor transmission rate (i.e., MVTR) of 1000 g / m when measured according to ASTM E96B standard on a 15 μm thick film of said polymer at 38° C. and 50% relative humidity. 2 / day or more, preferably 1500g / m 2 / day or more, more preferentially at least 2000g / m 2 / day, and preferentially at least 2500g / m 2 / day.

[0049] According to one embodiment, the highly breathable polymer is copolymers with polyamide and polyether blocks (i.e. TPA), such as the Pebax® products of the Arkema group; copoly(ether-urethane)s or thermoplastic polyurethanes (i.e. TPUs), such as Estane® from the Lubrizol group, Desmopan® from Covestro or ELASTOLLAN® from BASF, and Copoly(ester-ether) or thermoplastic elastomeric copolyesters (i.e. TPC), such as Arnitel® from DSM or Hytrel® from DuPont is selected from.

[0050] According to a preferred alternative, the highly breathable polymer is a copolymer having polyamide blocks and having polyether blocks.

[0051] The polyamide blocks of the copolymer having polyamide blocks and polyether blocks can be selected from blocks of polyamide 6, polyamide 11, polyamide 6.10, polyamide 6.12, polyamide 10.10, polyamide 10.12, polyamide 10.14, polyamide 12, and combinations thereof.

[0052] The polyether block of the copolymer having a polyamide block and a polyether block can be selected from polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol or polytetrahydrofuran (PTMG) blocks, and combinations thereof.

[0053] According to a more preferred alternative, the polyamide and polyether blocks are polyamide 11 (PA11) and polyethylene glycol (PEG) blocks, respectively, with molar masses ranging from 500 to 3000 g / mol. Such copolymers with polyamide and polyether blocks can be prepared according to either French patent application FR 2 846 332 in the name of Atofina or European patent application EP 1 482 011 in the name of Ube Industries.

[0054] Composition (a) may include one or more highly breathable polymers.

[0055] According to one embodiment, composition (a) comprises, based on its total weight: 50% to 100% by weight of highly breathable polymer(s), 0% to 30% by weight of additives selected from opacifiers, pigments, dyes, slip agents, antioxidants, antistatic agents, and antiblocking agents, and 0% to 20% by weight of a support thermoplastic resin for said additive It consists of:

[0056] The additives can be used in different amounts depending on the properties required.

[0057] Examples of suitable opacifiers, pigments or dyes include, but are not limited to, iron oxide, carbon black, aluminum, titanium dioxide, talc, and combinations thereof. An amount equivalent to 1% to 5% by weight is generally suitable.

[0058] Slip agents that can be used include, but are not limited to, higher fatty acid amides, higher fatty acid esters, waxes, silicone oils, and metal soaps. An example of a fatty acid slip additive that can be used is erucamide. In one embodiment, conventional polydialkylsiloxane additives with viscosities of 10,000 to 2,000,000 cSt, such as silicone oils or silicone gums, are used. The amount of these slip agents is typically in the range of 0.5% to 6% by weight.

[0059] Antioxidants (or stabilizers) are incorporated to protect composition (a) from decomposition caused by reaction with oxygen, which is susceptible to formation by the action of heat, light, or residual catalysts on certain components of composition (a), including highly breathable polymers. Examples of such compounds include primary antioxidants, which scavenge free radicals and are generally substituted phenols, such as Irganox® 1010 from Ciba. Primary antioxidants can be used alone or in combination with other antioxidants, such as phosphites, such as Irgafos® 168, also from Ciba, or UV stabilizers, such as amines. Antioxidants are generally incorporated in amounts that can range up to 5% by weight.

[0060] Antistatic agents that may be included in composition (a) in amounts ranging up to 20% by weight include alkali metal sulfonates, polyether-modified polydiorganosiloxanes, polyalkylphenylsiloxanes, tertiary amines, glycerol monostearate, mixtures of tertiary amines and glycerol monostearate, and combinations thereof. An example of a suitable antistatic agent is Armostat™ 475, available from Akzo Nobel.

[0061] Common antiblocking additives include, but are not limited to, inorganic compounds such as diatomaceous earth, natural or synthetic silica, talc, aluminum, potassium, calcium, and / or magnesium silicates, or organic compounds such as fatty acid amides, e.g., stearates. These antiblocking additives can be incorporated in amounts ranging from 1% to 7% by weight.

[0062] The support thermoplastic resin for the above additives is generally thermoplastic polyurethanes (i.e. TPU), such as TPU-esters or TPU-ethers -EVA (ethylene vinyl acetate copolymer) -EBA (ethylene and butyl acrylate copolymer) -TPC is selected from.

[0063] Considering the production of the monolayer film according to the present invention described later, it is advantageous to use these support resins.

[0064] According to a preferred alternative form of the invention, composition (a) consists of 80% to 100% by weight of highly breathable polymer(s) and 0% to 20% by weight of said additives and their support resins.

[0065] According to another preferred alternative form of the invention, composition (a) consists essentially of highly breathable polymer(s), more preferably consisting of highly breathable polymer(s).

[0066] In the above embodiment, when composition (a) of layer A contains TPA as the highly breathable polymer, the melt flow index (i.e., MFI) measured at a temperature of 190°C and a total weight of 2.16 kg is preferably in the range of 0.01 to 100 g / 10 min, and more preferably 0.1 to 50 g / 10 min.

[0067] In the above embodiment, when composition (a) of layer A contains TPU as the highly breathable polymer, the melt flow index (i.e., MFI) measured at a temperature of 190°C and a total weight of 8.7 kg is preferably in the range of 0.01 to 100 g / 10 min, and more preferably 1 to 80 g / 10 min.

[0068] Finally, in the above embodiment, when composition (a) of layer A contains TPC as the highly breathable polymer, composition (a) preferably exhibits a melt flow index (i.e., MFI) measured at a temperature of 230°C and with a total weight of 2.16 kg in the range of 0.01 to 200 g / 10 min, and more preferably 1 to 100 g / 10 min.

[0069] When considering the production of monolayer films according to the invention, as will be described below, it is advantageous to use these last three embodiments.

[0070] The melt flow index (or MFI) is measured at a specified temperature and total weight according to the ISO 1133 standard. The MFI is the weight of a composition (previously placed in a vertical cylinder) that flows through a die with a diameter of 2.095 mm in a specified time interval under the influence of pressure exerted by a loading piston with a specified total weight. By calculation, the specified time interval is reduced to 10 minutes.

[0071] Manufacturing method of monolayer film A Another subject of the invention is a method for producing a monolayer film A according to the invention, said method comprising the steps of: - step (i) of forming, by coextrusion, a multilayer film M comprising two layers B / A, Layer A is as defined above, Layer B is a peelable layer, having a thickness ranging from 15 to 100 μm, preferably from 20 to 55 μm, and consisting of a composition (b) in the form of a dispersion of high density polyethylene (HDPE) in a continuous phase of atactic polypropylene (PP), the amount of dispersed HDPE being such that Layer B exhibits an arithmetic mean roughness Ra of at least 0.1 μm on both sides thereof. Step (i) of forming a multilayer film M, then Step (ii) of peeling off layer B of multilayer film M to separate single layer film A Includes.

[0072] Surprisingly, it has been found that the specific composition (b) of layer B has the effect of creating a specific surface roughness on both sides thereof, which ensures that the surface of layer A in contact with layer B also has a substantially identical roughness.

[0073] Composition (b) of peelable layer B Composition (b) of the peelable layer B consists of a dispersion of high density polyethylene (HDPE) in a continuous phase of atactic polypropylene (PP).

[0074] Polypropylene is understood within the meaning of the present invention to mean a propylene homopolymer or a random copolymer of propylene with α-olefins which may be selected, as comonomers, in particular from ethylene, 1-butene, 1-pentene, 1-hexene, methyl-1-butene, 4-methyl-1-pentene and 1-decene.

[0075] In the scientific nomenclature of polymers, the term "tacticity" is used to describe the chain configuration, i.e., the stereochemical structure of the polymer chain.

[0076] A polymer is said to be isotactic if it has a chain configuration that can be described as having the radical groups attached to the tertiary carbon atoms of successive monomer units on the same side of an imaginary plane drawn through the main polymer chain. This type of stereochemistry can be shown diagrammatically as follows: TIFF2023548611000001.tif28170

[0077] Polypropylene with this type of chain configuration is known under the name isotactic polypropylene, or iPP.

[0078] Polypropylene chains can also adopt a syndiotactic configuration, in which the tertiary methyl groups of successive monomer units along the chain are arranged alternately on either side of an imaginary plane. The configuration of a syndiotactic chain can be described as follows: TIFF2023548611000002.tif26170

[0079] Polypropylene with this type of chain configuration is called syndiotactic polypropylene, or sPP.

[0080] In contrast to a regular spatial arrangement, propylene polymer chains can also have a chain stereochemistry characterized by a sterically random distribution of the methyl groups of successive monomer units on either side of an imaginary plane running through the polymer chain. This chain configuration is defined as atactic. The molecular chain configuration of atactic polypropylene (aPP) can be shown diagrammatically as follows: TIFF2023548611000003.tif28170

[0081] Atactic polypropylene is an essentially amorphous polymer and can be prepared by conventional methods using specific catalysts known to those skilled in the art, for example as described in EP 0 394 237. Atactic polypropylene is commercially available, for example, from BassTech International or PolymerTeam under the name APP Homopolymer (APPH) or APP Copolymer (APPC).

[0082] High density polyethylene (i.e., HDPE) can be produced by polymerization with Ziegler-Natta or metallocene type catalysis and has a density of 0.940-0.970 g / cm 3 This is widely available commercially, for example from Total.

[0083] The high density polyethylene (or HDPE) is generally present in the continuous phase of atactic PP in dispersion (b) in the form of nodules, the size of which is between 0.5 and 10 μm, preferably between 0.7 and 7 μm.

[0084] Dispersion (b) can be prepared in the form of granules having a size of 1 to 10 mm, preferably 2 to 6 mm, by simply heating and mixing PP granules having a size of 1 to 10 mm with HDPE in the form of a powder having constituent particles of about several hundred μm in size.

[0085] The amount of HDPE dispersed in the atactic polypropylene continuous phase is such that Layer B exhibits an arithmetic mean roughness Ra of at least 0.1 μm on both sides, Ra being defined and measured as set forth above.

[0086] According to a preferred alternative form of the process according to the invention, the amount of HDPE dispersed in the continuous phase of atactic polypropylene is such that the arithmetic mean roughness Ra is at least 0.3 μm, more preferably at least 0.5 μm.

[0087] Again, according to a preferred embodiment, the amount of HDPE dispersed in the continuous phase of atactic polypropylene is such that Layer B exhibits, on both sides thereof, in addition to the properties defined above for Ra, a number of peaks per unit length RPc of at least 40, preferably at least 50, and more preferably at least 60. The number of peaks per unit length RPc is also defined and measured as indicated above.

[0088] According to an equally preferred embodiment, the amount of HDPE dispersed in the atactic PP is in the range of 5% to 50% by weight, preferably 35% to 48% by weight, based on the total weight of the dispersion (b).

[0089] According to an alternative form of the invention, the dispersion (b) based on atactic PP advantageously comprises, in addition to HDPE, an antioxidant as defined above for composition (a), in a quantity that can vary from 0.5% to 5% by weight, based on the total weight of the dispersion (b).

[0090] According to another preferred alternative of the invention, composition (b) has a melt flow index (or MFI) of: in the range of 0.01 to 100 g / 10 min, preferably 0.1 to 50 g / 10 min, when measured at a temperature of 190 ° C and a total weight of 2.16 kg; in the range of 0.01 to 100 g / 10 min, preferably 1 to 80 g / 10 min, when measured at a temperature of 190 ° C and a total weight of 8.7 kg; When measured at a temperature of 230°C and a total weight of 2.16 kg, the range is 0.01 to 200 g / 10 min, preferably 1 to 100 g / 10 min The melt flow index is shown.

[0091] Step (i) and multilayer film M In the process for producing a monolayer film A according to the invention, the multilayer film M formed at the end of step (i) comprises two layers B / A as defined above.

[0092] According to a preferred embodiment of the present invention, the multilayer film M consists of the two layers B / A.

[0093] According to another equally preferred embodiment of the present invention, the multilayer film M comprises, preferably consists of, three layers B / A / C. Layer C is a peelable layer, the thickness of which ranges from 15 to 100 μm, preferably from 20 to 55 μm, and consists of a composition (c) of low-density polyethylene (LDPE), which also includes linear low-density polyethylene (LLDPE) and mixtures of LDPE and LLDPE. LDPE, i.e. low-density polyethylene, is understood to mean polyethylene produced by radical polymerization, the density of which is between 0.910 and 0.935 g / cm. 3 is within the range.

[0094] According to another more preferred embodiment of the present invention, the multilayer film M comprises, and preferably consists of, three layers B / A / C, layer C being a peelable layer that corresponds to the same definition as layer B and is identical (or different) to B. Even more particularly preferably, layers B and C are identical and are called S, and the multilayer film M is a symmetrical three-layer S / A / S.

[0095] Said multilayer film M is therefore an intermediate used in step (i) of the process according to the invention, which is also the subject of the present invention and the embodiment described above.

[0096] According to a first alternative of the invention, step (i) is carried out by flat coextrusion.

[0097] According to a second alternative form of the invention, which is preferred, step (i) is carried out by coextrusion by blown film extrusion.

[0098] According to a particularly preferred embodiment of this second alternative, step (i) comprises: - a step (i1) of introducing compositions (a), (b) and, where appropriate, (c) into separate extruders in the form of granules having a size between 1 and 10 mm, preferably between 2 and 5 mm, then - step (i2) of converting said granules into a molten state by heating, and then - step (i3) of passing the corresponding stream through an extrusion head equipped with a pair of coplanar and concentric annular dies, said head being at a temperature ranging from 150°C to 260°C so as to form, by injection of pressurized air, a cylindrical tubular bubble (or sheath) having several layers, the layer sequence corresponding to that desired in the final film, in the case of a two-layer B / A, layer A being on the outside of the tubular sheath, then - a step (i4) of radially expanding the bubble (relative to the plane of the annular die) and stretching (perpendicular to said plane), (i5) cooling the bubble (i5); Includes.

[0099] According to a preferred alternative, before step (i1), the granules to be introduced into the extruder are dried for a suitable time and at a suitable temperature.

[0100] The composition (a) introduced into the extruder, when it contains the additives described above, is advantageously provided in the form of a mixture comprising granules of a highly breathable polymer and granules of one or more masterbatches combining one or more additives with a support thermoplastic resin.

[0101] Stage (ii) Step (i) of forming the multilayer film M by coextrusion is followed by step (ii) of separating the monolayer film A by peeling off layer B and, if appropriate, layer C by simple mechanical separation, and then layer B and, if necessary, layer C are wound up on a number of cylinders different from the cylinder on which monolayer film A is wound up. Said mechanical separation can be carried out on an industrial scale, for example, by starting with two rolls of adhesive tape, the adhesive force of which to the outer surfaces of the two layers B / A is much greater than the adhesive force joining layer B to layer A. The separation of the monolayer film A by peeling is easy due to the incompatibility of composition (b) and composition (c) with respect to composition (a) and is carried out industrially by methods known to those skilled in the art.

[0102] The present invention also relates to a laminated product comprising a single-layer monolithic waterproof and breathable film according to the invention and a porous support layer made of a fibrous material.

[0103] The fibrous material may include a woven or nonwoven material, and the basis weight of the support layer may be 5 to 500 g / m 2 , preferably 10 to 300 g / m 2 You can change it up to.

[0104] The laminated products are often obtained by fixing the film to a support layer by lamination with a laminating adhesive, such as a polyurethane adhesive or a hot melt adhesive, which is applied by continuous or discontinuous coating by methods known to those skilled in the art.

[0105] Finally, the invention relates to the use of said laminated product for the manufacture of articles in particular in the field of textiles, especially clothing, in particular sportswear or protective surgical clothing, and personal protective equipment, as well as in the construction and health sectors.

[0106] The following examples are offered purely as illustrations of the present invention and should not be construed in any way to limit the scope of the present invention. [Example]

[0107] Example 1 (Comparative Example): Preparation of a monolithic, single-layer, waterproof, breathable film A1 of Pebax® copolymer with polyamide blocks and polyether blocks, including the formation by coextrusion of three layers S1 / A1 / S1, with layer S1 consisting of LDPE

[0108] The constituent composition (a1) of layer A1 is a copolymer containing polyamide blocks and polyether blocks, with a polyamide 11 block having a molar mass of 1000 g / mol and a polyethylene glycol (PEG) block having a molar mass of 1500 g / mol. The copolymer is available from Arkema under the name Pebax® and has an MFI of 20 g / 10 min, measured at 190 °C on a weight of 2.16 kg according to ISO 1133. The copolymer is available in the form of granules with a size between 2 and 6 mm.

[0109] The layer S1 is made of ExxonMobil's LDPE Escorene® 185JD, which has a density of 0.923 g / cm 3 and is provided in the form of granules having a size between 2 and 5 mm and an MFI of 2 g / 10 min measured at 190° C. for a weight of 2.16 kg.

[0110] (i) Formation of the three-layer film S1 / A1 / S1 The three-layer film was produced by a pilot coextrusion system using blown film extrusion, with a total flow rate of 15 to 35 kg / h and a die diameter of 7 cm.

[0111] This continuously operating device is equipped with a three screw extruder, the composition (a1) of layer A1 in a single screw extruder at a temperature of 180°C, - the composition of layer S1 is introduced into each of the other two screw extruders, the temperature of which is brought to 180°C. These compositions are in the form of granules approximately 4 mm in size.

[0112] The pilot device is equipped with an extrusion head, the annular die of which is brought to a temperature of 190°C.

[0113] The process parameters are adjusted to produce a three-layer film, which comprises: a layer A1 of composition (a1) having a thickness of 15 μm, - two identical support layers S1 made of LDPE and having a thickness of 30 μm; It consists of:

[0114] Among the parameters that are usually set, it is worth mentioning that the bubble expansion ratio is equal to 2.6, the drawing speed (corresponding to the line speed) is 10.7 m / min and the total throughput is 25 kg / h.

[0115] The three-layer film thus obtained is packaged in the form of a reel with a total thickness of 75 μm, a length of 50 m and a machine width of 280 mm.

[0116] (ii) Separation of layer A1 by delamination of two layers S1 Layer A1 is manually separated from the two layers S1 by peeling over a length of 2 m of film.

[0117] The samples of the layer A1 and the layer S1 thus obtained are subjected to the following measurements and tests.

[0118] Using a Bruker Dektak XT surface profilometer, the arithmetic mean roughness Ra and the number of peaks RPc are determined on one side of layer A1 and layer S1.

[0119] The results are shown in Table 1.

[0120] The gloss was measured on one of the faces of layer A1 using a Zehntner ZGM 1120 glossmeter according to the ASTM D 2457 standard at an angle of 60° to the normal of the sample surface drawn in the machine direction.

[0121] The gloss levels expressed in gloss units (GU) are shown in Table 1.

[0122] The breathability of layer A1 was quantified by measuring the MVTR at 38° C. and 50% relative humidity according to ASTM E96 B standard for a 15 μm thick film, the results of which are also shown in Table 1.

[0123] The coefficient of friction of layer A1 was measured according to the ISO 8295 standard of December 2004, as summarized below.

[0124] Measurement of the coefficient of friction The experimental setup is a non-movable horizontal test plate of suitable dimensions on which the sample of layer A1 is fixed.

[0125] A parallelepiped pad weighing 200g and measuring 63mm high, with a 4000mm 2 Another sample of the same layer A1 is also fixed with adhesive tape so as to cover the bottom surface of the square.

[0126] The pad is placed on a horizontal plate so that the two samples of layer A1 are in contact with each other, and then the pad is driven by a suitable drive mechanism in a displacement motion at a uniform speed of 150 mm / min against a stationary horizontal plate so that the two surfaces of layer A1 are in sliding contact with each other.

[0127] The resistance to displacement of the pad is measured by a dynamometer and recorded.

[0128] The coefficient of static friction Ks and the coefficient of dynamic friction Kd are calculated as indicated in the above mentioned standard.

[0129] The mean values ​​of Ks and Kd obtained after three repeated measurements were Ks=12.2, and Kd=12.1 is.

[0130] Example 2 (according to the invention): Preparation of a monolithic, single-layer, waterproof, breathable film A of a copolymer (TPA) having polyamide blocks and polyether blocks, including the formation by coextrusion of a three-layer S / A / S, layer S consisting of HDPE + atactic PP

[0131] Example 1, layer A has the same thickness and composition as layer A1, and The composition of layer S is an atactic PP dispersion in HDPE. This is repeated using the same method. This is produced by simple mixing of 44.9% by weight of HDPE, 1.6% by weight of antioxidant, and 53.5% by weight of atactic PP at 200°C, based on the total weight of the dispersion. The mixing is carried out in a twin-screw extruder equipped with a tool for cutting the extruded product at the die exit. Granules with a size between approximately 2 and 6 mm are obtained, which are fed into a two-screw extruder at a temperature of 210°C. The MFI measured for the dispersion is 1 g / 10 min at a weight of 2.16 kg and a temperature of 190°C.

[0132] The results obtained for the roughness for the two layers A and S, and for the gloss and breathability for layer A are given in Table 1.

[0133] The average values ​​obtained for the static friction coefficient Ks and the dynamic friction coefficient Kd of layer A are: Ks=0.7, and Kd=0.7 is.

[0134] Layer A of the monolithic waterproof and breathable film exhibits a surface roughness corresponding to Ra and RPc values ​​significantly higher than those observed for Layer A1 and Layer S1 of Example 1 according to the prior art. Furthermore, Layer A exhibits a more than 10-fold reduction in static and dynamic friction coefficients and a nearly 10-fold reduction in gloss, corresponding to a matte, non-glossy appearance, compared to Layer A1 of Example 1. Finally, the MVTR values ​​obtained for Layer A are comparable to those of Layer A1 of the prior art, demonstrating the excellent breathability characteristic of monolithic waterproof and breathable films.

[0135] Example 3 (Comparative): Preparation of a monolithic, single-layer, waterproof, breathable film A1 of Arnitel® copoly(ether-urethane) copolymer (TPC) including the formation by coextrusion of two layers B1 / A1, where layer B1 is made of LDPE.

[0136] Example 1 is repeated with the following exceptions. The constituent composition (a1) of layer A1 is a composition made of TPC Arnitel® PM381 obtained from DSM, whose MFI, measured at 230°C on a weight of 2.16 kg according to the ISO 1133 standard, is 4.7 g / 10 min. The process parameters are: a layer A1 of composition (a1) having a thickness of 15 μm, a single support layer B1 made of LDPE with a thickness of 30 μm; It was adjusted to produce a two-layer film with a total thickness of 45 μm consisting of Layer A1 is on the outside of the tubular sheath.

[0137] The results obtained for gloss and breathability for layer A1 are shown in Table 1.

[0138] Example 4 (according to the invention): Preparation of a monolithic, single-layer waterproof, breathable film A of TPC Arnitel®, including the formation by coextrusion of two layers B / A, where layer B is HDPE + atactic PP

[0139] Repeat Example 3 using the following: layer A has the same thickness and composition as layer A1, and Layer B consists of the same atactic PP dispersion in HDPE as used in Example 2.

[0140] The results obtained for gloss and breathability for Layer A are shown in Table 1.

[0141] Example 5 (according to the invention): Preparation of a monolithic, single-layer, waterproof, breathable film A of Desmopan® copoly(ether-urethane) (TPU) comprising the coextrusion of three layers B1 / A / C, layer B1 consisting of LDPE and layer C consisting of HDPE + atactic PP

[0142] Repeat Example 2 except using the following: layer A: Desmopan® 6590A MVT with a weight of 8.7 kg and an MFI of 6 g / 10 min at a temperature of 190° C.; layer B1, the LDPE of Example 1, and Layer C comprises a dispersion of atactic PP in the HDPE of layer S.

[0143] The gloss and breathability results obtained for Layer A are shown in Table 1, with the gloss results specified as to whether they were measured on the side of Layer A in contact with Layer B1 (referred to as "Side B1") or the side of Layer A in contact with Layer C (referred to as "Side C").

[0144] Example 6 (according to the invention): Preparation of a monolithic, single-layer, waterproof, breathable film A of Elastollan® copoly(ether-urethane) (TPU) comprising the formation by coextrusion of three layers B1 / A / C, layer B1 consisting of LDPE and layer C consisting of HDPE + atactic PP

[0145] Example 5 is repeated, except that layer A uses Elastollan® 1385A 12, weighing 8.7 kg and having an MFI of 25 g / 10 min at a temperature of 190°C.

[0146] The results obtained for gloss and breathability for Layer A are also shown in Table 1. TIFF2023548611000004.tif124170[Table 1] *: Gloss measured on the surface of layer A in contact with the second layer NC (Not Concerned) = Not Concerned NA (Not Available) = Not available

Claims

1. A single-layer monolithic waterproof and breathable film A having a thickness between 5 and 150 μm and comprising composition (a), wherein composition (a) is based on its total weight, - 50% to 100% by weight of one or more highly breathable polymers, - Additives in an amount of 0% to 30% by weight selected from opacifiers, pigments, dyes, slip agents, antioxidants, antistatic agents, and antiblocking agents, and - 0% to 20% by weight of a thermoplastic support resin for the additive It consists of, The opacifying agent, pigment, or dye is selected from iron oxide, carbon black, aluminum, and combinations thereof; the slip agent is selected from higher fatty acid esters, waxes, silicone oils, metal soaps, and combinations thereof; the antiblocking agent is selected from diatomaceous earth, potassium and / or calcium silicates, fatty acid amides, and combinations thereof. Film A is a single-layer monolithic waterproof and breathable film A characterized in that at least one of its two surfaces exhibits an arithmetic mean roughness Ra of at least 0.1 μm.

2. The single-layer monolithic waterproof and breathable film according to claim 1, characterized in that at least one of the two surfaces exhibits at least 40 peaks per unit length RPc.

3. A single-layer monolithic waterproof and breathable film according to claim 1 or 2, characterized in that both surfaces exhibit an arithmetic mean roughness Ra of at least 0.1 μm and at least 40 peaks per unit length RPc.

4. The highly permeable polymer is a thermoplastic elastomer polymer, and the water vapor transmission rate (MVTR) of the polymer is 1000 g / m² when measured according to the ASTM E96B standard at 38°C and 50% relative humidity for a 15 μm thick film of the polymer. ２ A single-layer monolithic waterproof and breathable film according to any one of claims 1 to 3, characterized in that it is more than one day.

5. A single-layer monolithic waterproof and breathable film according to any one of claims 1 to 4, characterized in that the highly breathable polymer is selected from copolymers having polyamide blocks and polyether blocks, copoli(ether-urethane), and copoli(ester-ether).

6. The single-layer monolithic waterproof and breathable film according to claim 5, characterized in that the highly breathable polymer is a copolymer having a polyamide block and a polyether block, wherein the polyamide block and the polyether block are a polyamide 11 (PA11) block and a polyethylene glycol (PEG) block, respectively, and their molar mass is in the range of 500 to 3000 g / mol.

7. A method for producing a single-layer monolithic waterproof and breathable film A having a thickness between 5 and 150 μm and comprising composition (a), wherein composition (a) contains at least 50% by weight of a highly breathable polymer based on its total weight, and at least one of two surfaces exhibits an arithmetic mean roughness Ra of at least 0.1 μm, and the method is as follows: - Step (i) of forming a multilayer film M containing two layers B / A by co-extrusion, - The composition (a) of layer A is as defined above, - Layer B is a release layer with a thickness in the range of 15 to 100 μm, and consists of a composition (b) in the form of a dispersion of high-density polyethylene (HDPE) in a continuous phase of atactic polypropylene (PolyPropylene: PP), wherein the amount of dispersed HDPE is such that layer B exhibits an arithmetic mean roughness Ra of at least 0.1 μm on both sides thereof. Step (i) of forming a multilayer film M, then - In the multilayer film M, the step of separating the single-layer film A by peeling off layer B (ii) A manufacturing method that includes this.

8. A method for producing a single-layer film A according to claim 7, characterized in that the amount of HDPE dispersed in Atactic PP is in the range of 5% to 50% by weight, when expressed based on the total weight of the dispersion (b).

9. A method for manufacturing a single-layer film A according to claim 7 or 8, characterized in that the multilayer film M consists of two layers B / A.

10. A method for producing a single-layer film A according to claim 7 or 8, characterized in that the multilayer film M comprises three layers B / A / C, and layer C is a release layer having a thickness in the range of 15 to 100 μm and is composed of a low-density polyethylene (LDPE) composition (c).

11. A method for manufacturing a single-layer film A according to claim 7 or 8, characterized in that the multilayer film M includes three layers B / A / C, and layer C is a release layer that corresponds to the same definition as layer B and is identical (or different) to B.

12. A method for manufacturing a single-layer film A according to any one of claims 7 to 11, characterized in that at least one of the two surfaces of the single-layer film A exhibits at least 40 peaks per unit length RPc.

13. The highly permeable polymer is a thermoplastic elastomer polymer, and the water vapor transmission rate (MVTR) of the polymer is 1000 g / m² when measured according to the ASTM E96B standard at 38°C and 50% relative humidity for a 15 μm thick film of the polymer. ２ A method for manufacturing a single-layer film A according to any one of claims 7 to 12, characterized in that the process takes at least one day.

14. A method for producing a single-layer film A according to any one of claims 7 to 13, characterized in that the highly permeable polymer is selected from copolymers having polyamide blocks and polyether blocks, copoli(ether-urethane), and copoli(ester-ether).

15. A method for producing a single-layer film A according to claim 14, characterized in that the highly permeable polymer is a copolymer having a polyamide block and a polyether block, the polyamide block and the polyether block being a polyamide 11 (PA11) block and a polyethylene glycol (PEG) block, respectively, and their molar mass being in the range of 500 to 3000 g / mol.

16. Composition (a) is, based on its total weight, - 50% to 100% by weight of (one or more) highly breathable polymers, - Additives in an amount of 0% to 30% by weight selected from opacifiers, pigments, dyes, slip agents, antioxidants, antistatic agents, and antiblocking agents, and - 0% to 20% by weight of a thermoplastic support resin for the additive A method for manufacturing a single-layer film A according to any one of claims 7 to 15, characterized by comprising the above.

17. A method for manufacturing a single-layer film A according to any one of claims 7 to 11, characterized in that the single-layer film A is as defined in any one of claims 1 to 6.

18. A multilayer film M comprising two layers B / A that can be used as an intermediate in the method according to any one of claims 7 to 17.

19. A laminated product comprising a single-layer monolithic waterproof and breathable film according to any one of claims 1 to 6, and a porous support layer made of a fibrous material.

20. Use of the laminated product according to claim 19 for the manufacture of articles in the fields of textiles, construction and health.