Description

Monolithic breathable membrane Cross-reference to Related Application

[0001 ] This application claims priority to European application No. 17172674.8 filed on May 24, 2017, the whole content of this application being incorporated herein by reference for all purposes.

Technical Field

[0002] The present invention relates to a monolithic breathable membrane, to processes for its manufacture thereof and to uses thereof.

Background Art

[0003] Breathable fabrics are typically designed for use in garments that provide protection from wind, rain and loss of body heat. Breathable fabrics are typically also waterproof (and hence referred to as waterproof breathable fabrics, WBF), in order to prevent the penetration and absorption of liquid water.

[0004] Water vapour-permeable polymer membranes have been used in sports apparel, fashion rainwear and protective work-wear since late 70s.

Increasingly therefore, WBF played an important role in outdoor clothing systems based on interactive layering and total moisture-management principles.

[0005] A review about "breathable" coatings and membranes, originally designed for foul-weather garments has been provided by LOMAX , George Robert. Breathable polyurethane membranes for textile and related industries. Journal of Material Chemistry. 2007, vol.17, p.2775-2784.

[0006] A well-known waterproof breathable textile laminate of commerce is sold under the trade name GORE-TEX®: it is based on the use of a membrane of hydrophobic, microporous, expanded polytetrafluoroethylene (PTFE) as an essential functional component. Typically, the microporous PTFE membrane is sandwiched between inner and outer fabric layers. This material, its preparation and its used have been described for example in US 3953566 (ROBERT W. GORE) and US 4787390 (ROBERT W. GORE) . Typically, breathable membranes from PTFE are prepared by stretching an unsintered highly crystalline PTFE sheet, prepared by paste extrusion. The resulting membranous PTFE product has a microstructure

characterized by fibrils.

[0007] Polyurethane compositions adapted to produce non-porous membrane exhibiting waterproof and water vapour transmissible characteristics have been disclosed in US 5238732 (SURFACE COATINGS, INC.) . Said membranes can be produced as free-standing products or as coatings on porous substrates. Such coated fabrics and fabric laminates can be used in the fabrication of tenting, rainwear and other garments.

[0008] Thermoplastic polyurethane polymers (TPU) have been widely used in textile industry, notably laminated onto a textile substrate, where they act as a highly breathable barrier that allows moisture vapour to escape out from the body, while preventing liquids, such as rain, from getting in.

Summary of invention

[0009] The Applicant noted that despite the effort made in the art, the need still exists of providing breathable materials, having both hydro- and oleo- repellence together with outstanding water vapour permeability properties, to be used in the textile industry.

[0010] Thus, in a first aspect, the present invention pertains to a monolithic

breathable membrane [membrane (D)] comprising at least one layer obtained from a composition [composition (C)] comprising:

- at least one fluorinated polyurethane (F-TPU polymer), said F-TPU polymer comprising recurring units deriving from:

[monomer (b)] at least one hydroxy-terminated (per)fluoropolyether polymer [PFPE polymer];

[monomer (c)] at least one aromatic, aliphatic or cycloaliphatic

diisocyanate; and

[monomer (d)] at least one aliphatic, cycloaliphatic or aromatic diol having from 1 to 14 carbon atoms, wherein said composition (C) comprises said F-TPU polymer in admixture with at least one poly-ethylene glycol (PEG).

[001 1] In a preferred embodiment, said F-TPU polymer further comprises

recurring units deriving from [monomer (a)] at least one diol selected from the group comprising poly-ether type diol, poly-ester type diol,

polybutadien-diol and polycarbonate-diol.

[0012] In further preferred embodiment, said F-TPU polymer further comprises recurring units deriving from [monomer (e)] at least one poly-ethylene glycol diol (PEG-d).

[0013] According to another preferred embodiment, said composition (C)

comprises said F-TPU polymer in admixture with at least one polyethylene glycol (PEG).

[0014] In a second aspect, the present invention relates to a process for

manufacturing a monolithic breathable membrane [membrane (D)], said process comprising:

(i) providing a composition [composition (C)] comprising at least one F- TPU polymer as defined above, at least one poly-ethylene glycol (PEG), and optionally at least one polar solvent;

(ii) processing the composition (C) provided in step (i) thereby providing said monolithic breathable membrane (D).

[0015] The monolithic breathable membrane (D) of the invention is

advantageously obtainable by the process of the invention.

[0016] In a further aspect, the present invention relates to a fabric comprising at least two layers, wherein at least one layer is made from the monolithic breathable membrane (D) as defined above.

Description of embodiments

[0017] For the purposes of the present description:

- the use of parentheses before and after symbols or numbers identifying compounds, chemical formulae or parts of formulae has the mere purpose of better distinguishing those symbols or numbers from the rest of the text and hence said parentheses can also be omitted;

- the term "(per)fluoropolyether" is intended to indicate a "fully or partially fluorinated polyether";

- the expression "(per)fluoropolyoxyalkylene chain" is intended to indicate a partially or fully fluorinated, straight or branched, polyoxyalkylene chain;

- the term "monolithic" is intended to indicate that the membrane is a dense polymeric membrane, typically in the form of a film, which is free from pores and pinholes;

- the terms "breathable" and "breathability" are intended to indicate the ability of a fabric to allow moisture vapour to be transmitted through the material, yet still preventing the penetration of liquid water from the outside. This property is evaluated according to ASTM E96/E96M;

- the expression "F-TPU polymer comprising recurring units deriving from" is intended to indicate that the F-TPU polymer is composed of recurring units obtained by reacting together at least monomer (b), monomer (c) and monomer (d), and optionally monomer (a) and monomer (e), for example through a condensation reaction.

[0018] Membrane (D) may be either a self-standing monolithic breathable

membrane or supported onto a substrate.

[0019] When the membrane is supported onto a substrate, membrane (D) is

obtained by laminating the monolithic breathable membrane onto a suitable substrate.

[0020] Said substrate is preferably selected from textile substrate and polymeric substrate, manufactured notably from olefins, such as polypropylene (PP), and fluorinated polymers, such as polytetrafluoroethylene (PTFE).

[0021] Preferably, said membrane (D) has a thickness of from 0.5 to 250 μηη, more preferably of from 1 to 200 μηη and even more preferably of from 5 to 150 m. Embodiments of said membrane (D) having a thickness of from 10 to 70 m are preferred within the present invention.

[0022] Preferably, the F-TPU polymer is a block copolymer, i.e. a polymer

comprising blocks (also referred to as "segments"), each block comprising recurring units deriving from monomer (b), monomer (c), monomer (d), as defined above, and monomer (a) and monomer (e) when present. [0023] Preferably, said F-TPU polymer has a weight average molecular weight (Mw) of from 30,000 to about 200,000 Da, determined by means of gel permeation chromatography (GPC) technique.

[0024] Preferably, said F-TPU polymer has a melting point (T _m ) of from about 120 °C to about 240°C.

[0025] When present, said monomer (a) has an average number molecular

weight preferably of from 500 to 4,000 Da, more preferably of from 1 ,000 to 4,000.

[0026] Preferably, said monomer (a) is a hydrogenated monomer, more

preferably selected in the group comprising poly(ethylene)glycol, poly(propylene)- glycol, poly(tetramethylen)glycol (PTMG), poly(1 ,4- butanediol)adipate, poly(ethandiol-1 ,4-butanediol) adipate, poly(1 ,6- hexandiol-neopentyl)glycol adipate, poly-caprolactone-diol (PCL) and polycarbonate-diol. Poly(tetramethylen)glycol, poly-caprolactone-diol and polycarbonate-diol being particularly preferred.

[0027] Preferably, said at least one monomer (b) is a hydroxy-terminated

(per)fluoropolyether polymer [PFPE polymer], i.e. a polymer comprising a (per)fluoropolyoxyalkylene chain [chain (R _P f)] having two chain ends, wherein one or both chain ends terminates with at least one -OH group.

[0028] Preferably, at least one chain end of said chain (R _P f) terminates with a

group of formula:

wherein

t is 0 or from 1 to 5.

[0029] More preferably, both chain ends of said chain (R _P f) terminate with a group of formula (I) as defined above.

[0030] Preferably, said chain (R _P f) is a chain of formula

-O-D-(CFX#)zi-O(Rf)(CFX ^* )z2-D ^* -O- wherein

z1 and z2, equal or different from each other, are equal to or higher than 1 , preferably from 1 to 10, more preferably from 1 to 3;

X ^# and X ^* , equal or different from each other, are -F or -CF3, provided that when z1 and/or z2 are higher than 1 , X ^# and X ^* are -F; D and D ^* , equal or different from each other, are an alkylene chain comprising from 1 to 6 and even more preferably from 1 to 3 carbon atoms, said alkyl chain being optionally substituted with at least one perfluoroalkyl group comprising from 1 to 3 carbon atoms;

(Rf) comprises, preferably consists of, repeating units R°, said repeating units being independently selected from the group consisting of:

(i) -CFXO-, wherein X is F or CF ₃ ;

(ii) -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is -F;

(iii) -CF2CF2CW2O-, wherein each W, equal or different from one other, is selected from F, CI, H;

(iv) -CF2CF2CF2CF2O-;

(v) -(CF2)j-CFZ-O- wherein j is an integer from 0 to 3 and Z is a group of general formula -O-R(f _-a )-T, wherein R(f _-a ) is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the following : -CFXO- , -CF2CFXO-, -CF2CF2CF2O-, -CF2CF2CF2CF2O-, with each of each of X being independently F or CF3 and T being a C1-C3 perfluoroalkyl group.

More preferably, chain (Rf) is selected from the following formulae (Rf-a) to

(Rf-a) -(CF2O)n(CF2CF2O) _m (CF2CF2CF2O)p(CF2CF2CF2CF ₂ O) _q - wherein m, n, p, q are 0 or integers selected in such a way as chain Rf meets the above number average molecular weight requirement, with the proviso that if, p and q are simultaneously 0, n is not 0; when m is other than 0, the m/n ratio is preferably between 0.1 and 20; when (m+n) is other than 0, (p+q)/(m+n) is preferably between 0 and 0.2;

(Rf-b) -(CF2CF(CF3)O)a(CF2CF2O)b(CF ₂ O)c(CF(CF3)O)d- wherein a, b, c, d are 0 or integers selected in such a way as chain Rf meets the above number average molecular weight requirement; with the proviso that, at least one of a, c and d is not 0; when b is other than 0, a/b is preferably between 0.1 and 10; when (a+b) is different from 0

(c+d)/(a+b) preferably is between 0.01 and 0.5, more preferably between 0.01 and 0.2; (Rf-c) -(CF ₂ CF(CF3)O)e(CF2O)f(CF(CF ₃ )O)g- wherein e, f, g are 0 or integers selected in such a way as chain Rf meets the above number average molecular weight requirement; when e is other than 0, (f+g)/e is preferably between 0.01 and 0.5, more preferably between 0.01 and 0.2.

[0032] PFPE polymers wherein chain (Rf) complies with formula (Rf-a) as defined above, wherein p and q are 0, are particularly preferred in the present invention.

[0033] In a preferred embodiment, said PFPE polymer complies with the following formula (PFPE-I):

HO-(CH2CH2O)t-CH2-(Rpf)-CH2(OCH ₂ CH2)u-OH (PFPE-I)

wherein

t and u are, each independently, 0 or from 1 to 5; and

R _P f is as defined above.

[0034] Preferably, said PFPE polymer has a weight average molecular weight of from 400 to 10,000 Da, more preferably from 1 ,000 to 5,000.

[0035] In a preferred embodiment, the molar ratio between monomers (a) (when present) and monomers (b) is from 2 to 20, more preferably from 2 to 10.

[0036] In a preferred embodiment, the amount of monomers (b) is such that the F-TPU polymer comprises from 1 to 80 wt.% of fluorine, preferably from 1 to 70 wt.% based on the weight of the F-TPU polymer.

[0037] Preferably, said at least one monomer (c) has a number molecular weight of 500 Da or lower, preferably from 10 to 500 Da.

[0038] Preferably, said at least one monomer (c) is selected in the group

comprising, preferably consisting of, 4,4'-methylene-diphenylene-di- isocyanate (MDI), 1 ,6-hexan-diisocyanate (HDI), 2,4-toluene-diisocyanate, 2,6-toluene-diisocyanate, xylylen-diisocyanate, naphthalene-diisocyanate, paraphenylen-diisocyanate, hexamethylen-diisocyanate, isophorone- diisocyanate, 4,4'-dicyclohexyl-methane-diisocyanate and cyclohexyl-1 ,4- diisocyanate.

MDI and HDI being particularly preferred.

[0039] Preferably, said at least one monomer (d) is selected in the group

comprising, preferably consisting of, ethylene-glycol, 1 ,4-butanediol (BDO), 1 ,6-hexane diol (HDO), Ν,Ν-diethanolamine and N,N- diisopropanolaniline. BDO and HDO being particularly preferred.

[0040] In a preferred embodiment, the sum of blocks deriving from monomers (c) and (d) is from 10 to 60 wt.% based on the total weight of the F-TPU polymer.

[0041] Preferably, said monomer (e) is at least one poly-ethylene glycol diol

(PEG-d) having a weight average molecular weight from 200 to 10,000, more preferably from 400 to 8,000.

[0042] Preferably, when present, said at least one monomer (e) is in an amount of from 5 to 75 wt.% based on the total weight of said F-TPU polymer, more preferably from 7 to 70 wt.%.

[0043] Preferably, mixtures of two or more than of said monomers (e) having different molecular weight are used. For example, but without any limitation, a mixture of a first monomer (e) having a weight average molecular weight of from 200 to 800, with a second monomer (e) having a weight average molecular weight of from 1 ,000 to 10,000, can be used.

[0044] Those skilled in the art would readily understand that blocks comprising recurring units derived from monomer (a), monomer (b) and monomer (e), when present, are rubber-like blocks, while blocks comprising recurring units derived from monomers (c) and (d) are hard blocks.

[0045] In a preferred embodiment, at least 80% of the blocks comprising recurring units derived from said monomers (b) [blocks B] are linked, at least one of their ends, to a block comprising recurring units derived from monomers (a) [blocks A] through a block comprising recurring units derived from monomers (c) [blocks C].

In other words, at least 80% of blocks B are contained in a sequence of the following type: -[A-C-B-C]-.

[0046] Advantageously, the F-TPU polymer can be prepared according to

methods known in the art, such as for example extrusion, injection moulding, casting of a solution of the monomers defined above or following the procedures disclosed in US 5332798 (AUSIMONT S.P.A.) . [0047] Preferably, said composition (C) comprises said F-TPU polymer in an amount of from 0.1 to 100 wt.% based on the total weight of said composition (C).

[0048] Preferably, said composition (C) further comprises at least one polar

organic solvent.

[0049] Preferably, said at least one polar organic solvent is selected from the group comprising, more preferably consisting of: N-methyl-pyrrolidone (NMP), dimethyl acetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO), tetrahydrofuran (THF), acetic acid, formic acid, methyl-5-dimethylamino-2-methyl-5-oxopentanoate (commercially available under the trade name Rhodialsov Polarclean®) and

triethylphosphate (TEP).

[0050] Preferably, said composition (C) comprises at least one F-TPU polymer in an amount of at least 1 wt.%, more preferably of at least 5 wt.%, based on the total weight of said composition (C).

[0051] Preferably, said composition (C) comprises at least one F-TPU polymer in an amount of at most 99 wt.%, more preferably of at most 95 wt.%, based on the total weight of said composition (C).

[0052] Even more preferably, composition (C) comprises at least one F-TPU

polymer in an amount from 55 to 90 wt.% based on the total weight of said composition (C).

[0053] Preferably, said composition (C) comprises at least one solvent in an

amount of at most 99 wt.%, more preferably of at most 95 wt.%, based on the total weight of said composition (C).

[0054] Preferably, said composition (C) comprises at least one solvent in an

amount of at least 1 wt.%, more preferably of at least 5 wt.%, based on the total weight of said composition (C).

[0055] Even more preferably, said composition (C) comprises from 10 to 45 wt.% of at least one solvent based on the total weight of said composition (C).

[0056] Preferably, said composition (C) comprises at least one further ingredient.

[0057] Suitable further ingredients are preferably selected in the group

comprising: plasticizers, nucleating agents, fillers, latent organic solvents, surfactants, and polymers different from the F-TPU polymer, such as for example polyvinylidenfluoride, polysulfones, polyethersulfones and hydrogenated thermoplastic polyurethane (TPU) polymers.

[0058] The amount of each of said further ingredients can be selected by the

person skilled in art. For example, each of said further ingredients can be used in an amount of from 0.01 to 30 wt.% based on the total weight of said composition (C).

[0059] Suitable plasticizers are preferably selected from the group comprising, preferably consisting of: phosphates, such as tricresyl phosphate;

phthalates, such as diethyl phthalate, dibutyl phthalate, dioctyl phthalate; sebactes, such as dioctyl sebacate.

[0060] Said polymers different from the F-TPU polymer are preferably added to composition (C) in an amount of from 0.05 to 15 wt.% based on the total weight of composition (C).

[0061] Preferably, when said composition (C) comprises said F-TPU polymer in admixture with at least one PEG, said PEG is in an amount of from 1 to 30 wt.%, more preferably from 5 to 20 wt.% based on total weight of said composition (C).

[0062] Under step (i) of the process for manufacturing membrane (D) according to the invention, the composition (C) is typically manufactured by any conventional techniques.

[0063] For example, composition (C) as defined above is prepared by mixing

together said at least one F-TPU polymer and said PEG as defined above, optionally at least one polar solvent, optionally one further ingredient, in any order.

[0064] Any suitable mixing equipment may be used. Preferably, the mixing

equipment is selected to reduce the amount of air entrapped in

composition (C) which may cause defects in the final membrane. The mixing of the F-TPU polymer, of the solvent, of the PEG and of any other further ingredient, may be conveniently carried out in a sealed container, optionally held under an inert atmosphere. Inert atmosphere, and more precisely nitrogen atmosphere has been found particularly advantageous for the manufacture of composition (C). [0065] The nnixing time during stirring required to obtain a clear homogeneous composition (C) can vary widely depending upon the rate of dissolution of the components, the temperature, the efficiency of the mixing apparatus, the viscosity of composition (C) and the like.

[0066] Under step (ii) of the process according to the present invention,

conventional techniques can be used for processing the composition (C) thereby providing a film.

[0067] The term "film" is used herein to refer to a layer of composition (C)

obtained after processing of the same under step (ii) of the process of the invention. The term "film" is used herein in its usual meaning, that is to say that it refers to a discrete, generally thin, dense layer.

[0068] Depending on the final form of the membrane, the film may be either flat, when flat membranes are required, or tubular in shape, when tubular or hollow fibre membranes are required.

[0069] According to a first embodiment of the invention, the process for

manufacturing membrane (D) is carried out in liquid phase.

[0070] The process according to this first embodiment preferably comprises:

(i ^A ) providing a liquid composition [composition (C ^L )] comprising:

- at least one F-TPU polymer as defined above,

- at least one poly-ethylene glycol (PEG), as above detailed; and

- at least one liquid medium [medium (L)];

(ϋ ^Λ ) processing composition (C ^L ) provided in step (i) thereby providing a film; and

(iii ^A ) drying the film provided in step (ii), thereby providing membrane (D).

[0071] The term "solvent" is used herein in its usual meaning, which is it indicates a substance capable of dissolving another substance (solute) to form a uniformly dispersed mixture at the molecular level. In the case of a polymeric solute, it is common practice to refer to a solution of the polymer in a solvent when the resulting mixture is transparent and no phase separation is visible in the system. Phase separation is taken to be the point, often referred to as "cloud point", at which the solution becomes turbid or cloudy due to the formation of polymer aggregates. The medium (L) preferably comprises at least one organic solvent.

Suitable examples of organic solvents are:

- aliphatic hydrocarbons including, more particularly, the paraffins such as, in particular, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane or cyclohexane, and naphthalene and aromatic hydrocarbons and more particularly aromatic hydrocarbons such as, in particular, benzene, toluene, xylenes, cumene, petroleum fractions composed of a mixture of alkylbenzenes;

- aliphatic or aromatic halogenated hydrocarbons including more particularly, perch lorinated hydrocarbons such as, in particular,

tetrachloroethylene, hexachloroethane;

- partially chlorinated hydrocarbons such as dichloromethane, chloroform, 1 ,2-dichloroethane, 1 ,1 ,1 -trichloroethane, 1 ,1 ,2,2-tetrachloroethane, pentachloroethane, trichloroethylene, 1 -chlorobutane, 1 ,2-dichlorobutane, monochlorobenzene, 1 ,2-dichlorobenzene, 1 ,3-dichlorobenzene, 1 ,4- dichlorobenzene, 1 ,2,4-trichlorobenzene or mixture of different

chlorobenzenes;

- aliphatic, cycloaliphatic or aromatic ether oxides, more particularly, diethyl oxide, dipropyl oxide, diisopropyl oxide, dibutyl oxide,

methylterbutyl ether, dipentyl oxide, diisopentyl oxide, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether benzyl oxide; dioxane, tetrahydrofuran (THF);

- dimethylsulfoxide (DMSO);

- glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether;

- glycol ether esters such as ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate;

- alcohols, including polyhydric alcohols, such as methyl alcohol, ethyl alcohol, diacetone alcohol, ethylene glycol; - ketones such as acetone, methylethylketone, methylisobutyl ketone, diisobutylketone, cyclohexanone, isophorone;

- carboxylic acids such as, formic acid, acetic acid, propionic acid, oxalic acid, oxoacetic acid, glycolic acid, chloroacetic acid, trifluoroacetic acid;

- linear or cyclic esters such as isopropyl acetate, n-butyl acetate, methyl acetoacetate, dimethyl phthalate, γ-butyrolactone;

- linear or cyclic carboxamides such as Ν,Ν-dimethylacetamide (DMAc), Ν,Ν-diethylacetamide, dimethylformamide (DMF), diethylformamide or N- methyl-2-pyrrolidone (NMP);

- organic carbonates for example dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, ethylmethyl carbonate, ethylene carbonate, vinylene carbonate;

- phosphoric esters such as trimethyl phosphate, triethyl phosphate (TEP);

- ureas such as tetramethylurea, tetraethylurea;

- methyl-5-dimethylamino-2-methyl-5-oxopentanoate (commercially available under the trade name Rhodialsov Polarclean®).

[0073] If required, said medium (L) can further comprise at least one latent

organic solvent.

[0074] For the purpose of the present invention, the term "latent" is intended to denote an organic solvent, which behaves as an active solvent only when heated above a certain temperature.

[0075] Preferably, said at least one organic solvent is selected from at least one polar solvent, such as those listed above and combinations thereof.

[0076] The medium (L) preferably comprises at least 40 wt.%, more preferably at least 50 wt.% based on the total weight of said medium (L), of at least one organic solvent. Medium (L) preferably comprises at most 100 wt.%, more preferably at most 99 wt.% based on the total weight of said medium (L), of at least one organic solvent.

[0077] Under step (i ^A ), composition (C ^L ) is manufactured by any conventional techniques. For instance, the medium (L) may be added to the F-TPU polymer, or, preferably, the F-TPU polymer may be added to the medium (L), or even the F-TPU polymer and the medium (L) may be

simultaneously mixed. [0078] Any suitable mixing equipment may be used. Preferably, the mixing equipment is selected to reduce the amount of air entrapped in

composition (C ^L ) which may cause defects in the final membrane. The mixing of the F-TPU polymer and the medium (L) may be conveniently carried out in a sealed container, optionally held under an inert

atmosphere. Inert atmosphere, and more precisely nitrogen atmosphere has been found particularly advantageous for the manufacture of composition (C ^L ).

[0079] Under step (i ^A ), the mixing time during stirring required to obtain a clear homogeneous composition (C ^L ) can vary widely depending upon the rate of dissolution of the components, the temperature, the efficiency of the mixing apparatus, the viscosity of composition (C ^L ) and the like.

[0080] Under step (ϋ ^Λ ), composition (C ^L ) is typically processed in liquid phase.

[0081] Under step (ϋ ^Λ ), composition (C ^L ) is typically processed by casting thereby providing a film.

[0082] Casting generally involves solution casting, wherein typically a casting knife, a draw-down bar or a slot die is used to spread an even film of a liquid composition comprising a suitable medium (L) across a suitable support.

[0083] Under step (ϋ ^Λ ), the temperature at which composition (C ^L ) is processed by casting may be or may be not the same as the temperature at which composition (C ^L ) is mixed under stirring.

[0084] Different casting techniques are used depending on the final form of said membrane (D).

[0085] Under step (iii ^A ), drying is preferably performed in a static or ventilated oven or under vacuum.

[0086] Suitable conditions for performing step (iii ^A ), notably the drying

temperature, the ventilation rate and the drying time, can be selected by the person skilled in the art depending on the nature of medium (L), as well as on its concentration, and also on the thickness of the film to be dried, as formed under step (ϋ ^Λ ). When required, a temperature ramp is advantageously set for said step (iii ^A ). [0087] When the final product is a flat membrane (D), composition (C ^L ) is cast as a film over a flat supporting substrate, typically a plate, a belt or a fabric, or another microporous supporting membrane, typically by means of a casting knife, a draw-down bar or a slot die.

[0088] According to a first embodiment of step (ϋ ^Λ ), composition (C ^L ) is processed by casting onto a flat supporting substrate to provide a flat film.

[0089] According to a second embodiment of step (ϋ ^Λ ), composition (C ^L ) is

processed to provide a tubular film. Said tubular film can be provided onto a supporting substrate or as a self-standing tubular film.

[0090] According to a variant of this second embodiment of step (ϋ ^Λ ), the tubular film is manufactured using a spinneret.

[0091] Membrane (D) obtainable by the process according to the first

embodiment may undergo additional post treatment steps, for instance rinsing and/or stretching.

[0092] Membrane (D) obtainable by the process according to the first

embodiment of the invention is typically rinsed using a liquid medium miscible with the medium (L).

[0093] Membrane (D) obtainable by the process according to the first

embodiment of the invention may be advantageously stretched.

[0094] According to a second embodiment of the invention, the process for

manufacturing membrane (D) is carried out in molten phase.

[0095] The process according to the second embodiment of the invention

preferably comprises the following steps:

(ί ^ΛΛ ) providing a solid composition [composition (C ^s )] comprising at least one F-TPU polymer as defined above and at least one poly-ethylene glycol (PEG) as above detailed;

(ϋ ^ΛΛ -Α) processing the composition (C ^s ) provided in step (ί ^ΛΛ ) thereby providing a film and (ίϋ ^ΛΛ -Α) stretching the film provided in step (ϋ ^ΛΛ -Α) thereby providing a membrane; or

(ϋ ^ΛΛ -Β) processing the composition (C ^s ) provided in step (ί ^ΛΛ ) thereby providing fibers and (ίϋ ^ΛΛ -Β) processing the fibers provided in (ϋ ^ΛΛ -Β) thereby providing membrane (D). [0096] Under step (ϋ ^ΛΛ -Α), composition (C ^s ) is preferably processed in molten phase.

[0097] Melt forming is commonly used to make dense films by film extrusion, preferably by flat cast film extrusion or by blown film extrusion.

[0098] According to this technique, composition (C ^s ) is extruded through a die so as to obtain a molten tape, which is then calibrated and stretched in the two directions until obtaining the required thickness and wideness.

Composition (C ^s ) is melt compounded for obtaining a molten composition. Generally, melt compounding is carried out in an extruder. Composition (C ^s ) is typically extruded through a die at temperatures of generally lower than 250°C, preferably lower than 200°C thereby providing strands which are typically cut thereby providing pellets.

[0099] Twin screw extruders are preferred devices for accomplishing melt

compounding of composition (C ^s ).

[0100] Films can then be manufactured by processing the pellets so obtained through traditional film extrusion techniques. Film extrusion is preferably accomplished through a flat cast film extrusion process or a hot blown film extrusion process. Film extrusion is more preferably accomplished by a hot blown film extrusion process.

[0101] Under step (ίϋ ^ΛΛ -Α), the film provided in step (ϋ ^ΛΛ -Α) may be stretched either in molten phase or after its solidification upon cooling.

[0102] Membrane (D) obtainable by the process of the invention is typically dried, preferably at a temperature of at least 30°C.

[0103] Drying can be performed under air or a modified atmosphere, e.g. under an inert gas, typically exempt from moisture (water vapour content of less than 0.001 % v/v). Drying can alternatively be performed under vacuum.

[0104] Membrane (D) of the invention may be in the form of flat membranes or in the form of tubular membranes.

[0105] Flat membranes are generally preferred within the present invention.

[0106] If required by the final use, at least one surface of said membrane (D) can be treated to modify its surface properties, for example by physical or chemical treatment such as plasma treatment, corona treatment and chemical surface finishing. [0107] Advantageously, membrane (D) according to the present invention allows manufacturing a waterproof breathable fabric, as it allows reducing or preventing water penetration from the outside to the inside, while aiding water vapour transport from the inside to the outside.

[0108] Waterproof breathable fabrics (WBF) are typically manufactured as

continuous rolls of 1.5 to 2 meters wide and 100 to 5000 meters long.

[0109] The waterproof breathable fabric according to the present invention

preferably comprises a first layer comprising a substrate and a second layer, adhered to said first layer, comprising membrane (D).

[01 10] Waterproof breathable fabric(s) according to the present invention can be manufactured for example as follows:

- providing a substrate, such as for example woven substrates, knitted substrates or polymeric substrates;

- contacting said substrate with composition (C) as defined above;

- optionally, transfer coating; and

- lamination, so as to provide a fabric comprising said membrane (D) as defined above onto said substrate.

[01 1 1] Advantageously, in order to protect membrane (D) from the external

environment, at least one third layer can be provided onto the layer comprising said membrane (D).

[01 12] For example, said third layer can comprise a tri-coat mesh or a durable water repellent (DBR) layer can be provided onto membrane (D).

[01 13] Accordingly, the final fabric according to the invention will comprise a first layer comprising at least one substrate as defined above, a second layer comprising membrane (D) according to the present invention and a third layer, preferably comprising said tri-coat mesh or said DBR layer, wherein said second layer is interposed between said first layer and said third layer.

[01 14] Optionally, an insulating layer can be provided between said first layer comprising the substrate and said second layer comprising the membrane (D).

[01 15] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[01 16] The invention will be herein after illustrated in greater detail by means of the Examples contained in the following Experimental Section; the

Examples are merely illustrative and are by no means to be interpreted as limiting the scope of the invention.

Experimental Section

[01 17] Materials

- Monomer (a):

CAPA™ 2201 (from Perstorp) polycaprolactone-diol (PLC) having molecular weight (Mw) of about 2,000 and -OH value of about 56 mg KOH/g;

- Monomer (b) having formula:

H(OCH2CH2)pOCH2CF2O(CF2CF2O) _m (CF2O)nCF2CH2O(CH2CH ₂ O)pH with p=4.7 and Mw of about 2,000

- Monomer (c):

diphenylen-4,4'-diisocyanate (MDI)

- Monomer (d):

1 ,4-butanediol (BDO)

- Catalyst:

zinc neodecanoate

- Solvents and additives were obtained from Sigma Aldrich:

dimethylacetamide (DMAc)

polytehtylen glycol (PEG) 6000

[01 18] Methods

[01 19] Preparation of F-TPU polymer specimens

F-TPU polymer specimen 1 and comparative H-TPU 1 were prepared starting from the abovementioned monomers following the same procedure detailed in Example 15 of US 5,332,798 (to Ausimont S.p.A.) cited above. The monomers were used in the molar ratios reported in the following Table 1 .

Table 1 Monomers (molar ratio) a b c d

F-TPU 1 0.75 0.25 3.0 2.0

F-TPU 2 0.29 0.71 3.0 2.0

H-TPU 1 ( ^* ) 1.0 - 3.0 2.0

[0120] ( ^* ) comparison

[0121] Solution preparation

[0122] Solutions were prepared by adding each polymer and optionally, the

additive PEG 6000 (F-TPU/PEG6000 ratio being 10/1 by weight) in the solvent (DMAC). The solvent concentration was 90% w/w.

[0123] After mixing, stirring was performed with a mechanical anchor for 4 hours at room temperature (RT).

[0124] Monolithic breathable membrane preparation

[0125] Flat monolithic breathable membranes were prepared by filming the

polymeric solution obtained following the procedure disclosed above, over a suitable smooth glass support by means of an automatized casting knife, at 40°C. The knife gap was set at 500 μηη. After casting, the solvent was left to evaporate in a vacuum oven at 130°C for 4 hours.

[0126] The membranes were prepared such that the specimens obtained were suitable for the evaluation according to ASTM E96/96M and ASTM D5725- 99.

[0127] Measurement of the weight average molecular weight

[0128] The weight average molecular weight of the F-TPU polymers was

determined by means of gel permeation chromatography (GPC)

technique.

[0129] A solution of each F-TPU polymer was prepared in tetrahydrofuran (THF) at 0.5 %wt./vol. concentration. The solution was then centrifuged at 20,000 rpm for 60 minutes at room temperature using a Sorvall RC-6 Plus centrifuge and the supernatant was injected in the GPC apparatus. To correlate retention time and molecular weights, a calibration curve was calculated from narrow standards of polystyrene having molecular weights from 1 ,700 to 4,000,000 Da.

[0130] Measurement of contact angle (CA)

The contact angle towards water and hexadecane (C16) was evaluated at 25°C by using the DSA10 instrument (from Kruss GmbH, Germany) according to ASTM D5725-99. The results are reported in Table 2.

[0131] Water vapour permeability test (WVT)

[0132] Water vapour permeability was measured according to ASTM E96/96M using the Water Method.

[0133] A membrane specimen (from each of the Polymer Composition as detailed in the Table below) with shape and size suitable to be used in the apparatus described in ASTM E96/E96M, was sealed to the open mouth of a test dish containing distilled water. The assembly was then placed in a climatic chamber with controlled atmosphere. Periodic weighting

determined the rate of water vapour movement through the specimen from the water present in the controlled atmosphere. The temperature was set at 38°C and the relative humidity of the climatic chamber was measured and found equal to 10%. In the test dish, the relative humidity was nominally 100%.

[0134] Water vapour transmission (WVT) was expressed as g/m ^2* day. From this WVT value, the absolute permeability values were obtained from the thickness of the specimens (in micrometres) and the driving force, which was expressed from the formula:

driving force = S ^* (100-10)/100

wherein S is the saturation vapour pressure of water at 38°C and 6650 Pa.

[0135] The permeability data are reported in Table 2.

Table 2

Polymer composition CA water (°) CA C16 (°) Permeability

m/m ^2* day ^* Pa) F-TPU 1 ( ^* ) 106 68 4.77

F-TPU 2( ^* ) 101 64 3.31

F-TPU 1 in admixture with 100 68 7.02

PEG6000

H-TPU 1 ( ^* ) 93 wet N/P

H-TPU 1 ( ^* ) in admixture 40 wet N/P

with PEG6000

[0136] ( ^* ) comparison

[0137] N/P indicates that the test was not performed because the oleo-repellency value (CA C16) was not sufficient.

The results reported in Table 2 showed that the addition of PEG moiety in the composition for preparing the membrane according to the invention allowed increasing the permeability, without however negatively affecting the hydro-repellency and the oleo-repellency.