Semi-permeable membrane with pores resulting from volatile substance Description

The current application is directed to a porous film based on polymers, preferably thermoplastic polymers, even more preferably thermoplastic polyurethane, their production process and its use for clothing especially rain protecting clothing.

Membranes for different purposes are well known to the public. Membranes are in particular used for separation purposes. For many applications, high water resistance is needed in combi nation with vapor permeability.

Such membranes commonly are based on polytetrafluoroethylen (pTFE) films with nano- and micro voids, that support vapor permeability and are water resistant. Due to environmental is sues alternative routes are developed for substituting this material.

US 2019/001279 as well as WO / 072754 are describing production processes for films based on thermoplastic polyurethane with high water resistance and at the same time good vapor per meability. EP 2 805 759, US 2010 / 0155325 A1 , GB 2174 641 and WO 2019 / 072 754 de scribe a production process for a membrane, which comprises a leaching step. JP 989954 dis closes a production process for porous membranes usable for filters based on polytetrafluoro- ethylene, with a production process being a strain on the environment.

Whereas all the production processes are complex, cost intensive or the materials used have technical or environmental disadvantages, respectively low accepetance at the customer.

Therefore, it was the need to find a suitable material , with good water resistance, vapor perme ability and very good mechanical properties with a better production process.

Surprisingly this could be achieved by using appropriate volatile substances, form a film com prising the polymer, preferably a thermoplastic polyurethane and removing the volatile sub stance thereafter from thecomposition, preferably from the film, by heating and/or reducing pressure.

Therefore, one aspect and embodiment No. 1 of the present invention is a process for produc ing a film with pores from a composition comprising a polymer, preferably a thermoplastic polyu rethane, preferably being the reaction product of a diisocyanate, a polyol with a functionality of 2, and further preferably a chain extender, preferably with a functionality of 2, by adding a vola tile substance to the composition, form the composition to a film and remove the substance from the film by heating the film under atmospheric pressure, or by reducing the pressure under the atmospheric pressure, or by heating the film and reducing the pressure under the atmospheric pressure.

Heating may e.g. affect features of the film, such as mechanics or the like, therefore in some preferred cases it is better to reduce the pressure in the production process under the atmos pheric pressure. In yet another embodiment the film is heated and the pressure is reduced, pref erably at the same time. This allows a quicker production process compared to only reducing the pressure.

Another preferred embodiment 2 is the process according to the precedent embodiment, wherein the composition is heated beyond the temperature Tv where the substance is volatile under respective pressure. In a preferred embodiment the Tv is measured by thermogravimetric analysis (TGA). Thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes The TGA instrument con tinuously weighs a sample as it is heated to temperatures. As the temperature increases, vari ous components of the sample are decomposed and the weight percentage of each resulting mass change can be measured.

In a preferred embodiment the TGA is measured according to DIN EN ISO 1 1385. Preferrably the device for measurement ist first flown with nitrogen, preferably for at least 5 minutes. This allows to achieve a pure nitrogen atmosphere in the sample cavity. Then the sample is heated up, preferably with a rate of 2.5, 5,10 or 15 K/min, most preferred 5 K/min. During the heating the weight loss will be measured continuously. To define the decomposition temperature, in one preferred embodiment the extrapolated onset temperature is calculated. The onset temperature denotes the temperature at which the weight loss begins, which is the volatile temeperature. In another preferred embodiment the 1 st derivative of the weight loss curve indicates the point of greatest rate of change on the weight loss curve.

Another preferred embodiment 3 is the process according to any of the precedent embodi ments, wherein the polymer composition is either thermoplastic or is not thermoplastic, and in case the composition is thermoplastic, the substance is volatile at a temperature Tv at least 10 °C below the melting temperature Tm of the thermoplastic polymer composition or, in case the polymer is not thermoplastic, the substance is volatile at a temperature Tv at least 10 °C below the degradation temperature Td of the polymer.

In a preferred embdoment 4 the process according to any of the precedent embodiments wherein the volatile substance has a decomposition temperature of less than 130°C, preferably less than 100°C. In a preferred embodiment 5 in the process of any of the precedent embodiments the volatile substance is selected from the group comprising azodicarbon amide, 4,4'-oxy bis(benzene Sul- fonyl hydrazide), p-toluene sulfonyl hydrazide, azo bis isobutylodinitrile, azodiaminobenzene, azohexahydrobenzodinitrile, barium azodicarboxylate, N,N'-dinitrosopentamethylene tetramine, N,N'-dinitroso-N, N'-dimethylterephthalamide, t-butyl aminonitrile, p-toluene sulfonylacetone hy- drazone; citric acid, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, am monium carbamate, ammonium acetate, ammonium hydrogen sulfate, ammonium malate, azodicarbonamide, sodium hydrogene carbonate, diaminodiphenylsulphone, hydrazide, malonic acid, citric acid, sodium monocitrate, urea, azodicarbonic methyl ester, diazabicylooctane, or is a mixture thereof. The volatile substance preferably is a powder, preferably with diamaters as outlined in the production process below.

In another preferred embodiment 6 is the process according to any of the precedent embodi ments or one of their preferred embodiment, wherein the substance is selected from the group comprising, preferably consisting of sodium bicarbonate, ammonium carbamate, ammonium carbonate (NH^COa, ammonium acetate (CH ₃ COONH ₄ ), ammonium hydrogen sulfate

((NH ₄ )HSC>4), ammonium malate (C4H12N2O5), ammonium hydrogen carbonate (NH4HCO3), so dium hydrogen carbonate (NaHCOa), or is a mixture thereof; even more preferred the substance is selected from the group comprising, more preferably consisting of, ammonium hydrogen car bonate NH4HCO3, ammonium carbonate (Nh^COa and ammonium carbamate H ₂ NCOONH ₄ ,or preferably, is a mixture thereof.

Another preferred embodiment 7 is the process according to any of the precedent embodiments or their preferred embodiments, wherein the polymer is a thermoplastic polymer, preferably se lected from the group comprising polyamide, polyester, poly (ether-ester) copolymer, polyeth- erimide, polyetherether ketone, polyacrylate, polyvinylchloride (PVC), polytetrafluoroethylene (pTFE), polycarbonate, polyethylene, polypropylene, polyurea, polystyrene, polylactic acid, poly- oxymethylene, acrylonitrile butadiene styrene (ABS), polyimide, thermoplastic polyurethane, or is a mixture thereof.

Thermoplastic polyurethane

Another preferred embodiment 8 is the process according to any of the precedent embodi ments, comprising all the features of any of the precedent embodimets, or their preferred em bodiments, wherein the polymer comprises a thermoplastic polyurethane, preferably is a ther moplastic polyurethane. Production process of thermoplastic polyurethane (TPU)

Preferably the thermoplastic polyurethane is prepared by reacting (a) isocyanates with (b) a compound having two functional groups reactive with isocyanate, preferably having a number average molecular weight of from 0.5 x 10 ³ g /mol to 100 x 10 ³ g /mol and, if desired, (c) chain extenders, preferably having a molecular weight of from 0.05 x 10 ³ g /mol to 0.499 x 10 ³ g /mol, if desired in the presence of (d) a catalysts and/or (e) an auxiliary and/or an additive.

The components (a) isocyanate, (b) compound reactive towards isocyanates, in a preferred em bodiment a polyol, and (c) chain extenders are also addressed individually or together as struc tural components. The build-up components including the catalyst and/or the auxiliary and/or the additive are also called input materials.

In order to adjust the hardness and melt index of the TPU, the molar ratios of the quantities of the build-up components (b) and (c) used can be varied, whereby the hardness and melt viscos ity increase with increasing content of chain extender (c), while the melt index decreases.

For the production of softer polyisocyanate polyaddition product, preferably thermoplastic polyu rethanes, preferably those having a Shore A hardness of less than 95, more preferably from 95 to 75 Shore A, the difunctional polyol (b), preferably also be referred to as polyhydroxyl com pounds (b), and the chain extenders (c) may advantageously be used in mole ratios of 1 :1 to 1 :5, preferably 1 :1 .5 to 1 :4.5, such that the resulting mixtures of the structural components (b) and (c) have a hydroxyl equivalent weight of greater than 200, and in particular from 230 to 450, while for the production of harder TPU, e. g. those having a Shore A hardness greater than 98, preferably 55 to 75 Shore D, the molar ratios of (b):(c) being in the range of 1 :5.5 to 1 :15, pref erably 1 :6 to 1 :12, such that the resulting mixtures of (b) and (c) have a hydroxyl equivalent weight of 1 10 to 200, preferably 120 to 180.

In order to prepare the thermoplastic polyurethane, the building components (a), (b), in a pre ferred embodiment also the chain extender (c), are reacted in the presence of a catalyst (d) auxiliaries and/or additives (e) in such quantities that the equivalent ratio of NCO groups of the diisocyanates (a) to the sum of the hydroxyl groups of the components (b) and (c) is 0.95 to 1 .10:1 , preferably 0.98 to 1 .08:1 and in particular approximately 1 .0 to 1 .05:1 .

The thermoplastic polyurethane, has preferably a weight-average molecular weight of at least 0.1 x10 ⁶ g/mol, preferably of at least 0.4 x 10 ⁶ g/mol and in particular of at least 0.6 x10 ⁶ g/mol. The upper limit for the weight-average molecular weight of TPU is generally determined by the processability and the desired range of properties. Preferably the number average molecular weight does not exceed 0.8 x10 ⁶ g/mol. The mean molecular weights are the weight averages determined by gel permeation chromatography. The number average molecular weight Mn in the context of this invention is determined by gel permeation chromatography, preferably it is determined according to DIN 55672-1.

Isocyanate

The isocyanate preferred in an embodiment 9 according to the process any of the the precedent embodiments prdocuing thermoplastic polyurethane, or one of its preferred embodiments, is an organic isocyanate (a), more preferred is aliphatic, cycloaliphatic, araliphatic and/or aromatic, and further preferred is selected from the groups consisting of tri-, tetra-, penta-, hexa-, hepta- and/or octamethylene diisocyanate, 2-methyl-pentamethylene 1 ,5-diisocyanate, 2-ethyl-butyl- ene-1 , 4-diisocyanate, 1 ,5-pentamethylene diisocyanate, 1 ,4- butylene-diisocyanate, 1 -isocya- nato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1 ,4- bis(isocyanatomethyl)cyclohexane and/or 1 ,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4- paraphenylene diisocyanate (PPDI), 2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-,

2,4'- and 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1 ,6-hexamethylene diisocyanate (HDI),1 ,4-cyclohexane diisocyanate, 1 -methyl-2,4- and/or -2,6-cyclohexane diisocyanate, 2,2'-, 2,4'- and/or 4,4'-diphenylmethane diisocyanate (MDI), 1 ,5-naphthylene diisocyanate (NDI), 2,4- and/or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyl-diphenyl diisocyanate, 1 ,2-diphenylethane diisocyanate and/or phenylene diisocyanate, or is a mixture thereof.

Preferably the isocyanate for producing thermoplastic polyurethane is selected from the group consisting of diphenylmethane disocyanate (MDI), toluene diisocyanate (TDI), isophorone diiso cyanate (IPDI), hexamethylene diisocyanate (HDI), methylene bis (4-cyclohexylisocyanate) (HMDI), or is a mixture thereof.

In a very preferred embodiment 10 according to any of the precedent embodiments of the pro cess described herein producing thermoplastic polyurethane, or one of their preferred embdoi- ments, the isocyanate is 2,2'-, 2,4'- and/or 4,4'-diphenylmethane diisocyanate (MDI).

Polyol for TPU

The compound reactive with isocyanate, also referred to as isocyanate-reactive compound (b) in a preferred embodiment 1 1 the process according to any of the precedent embodiments for producing thermoplastic polyurethane, or one of their preferred embodiments, has on statistical average at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms, this number is also re ferred to as the functionality of the isocyanate-reactive compound (b) and indicates the quantity of the isocyanate-reactive groups of the molecule calculated theoretically down to one molecule from a quantity of substance. The functionality is preferred between 1 .8 and 2.6, further pre ferred between 1.9 and 2.2 and especially preferred 2. In a preferred embodiment 12 in the process according to any of the precedent embodiments the compound (b) reactive towards iso cyanates are preferably those having a molecular weight between 0.500 g/mol and 8 x10 ³ g/mol, preferably 0.7 x 10 ³ g/mol to 6.0 x 10 ³ g/mol, in particular 0.8 x 10 ³ g/mol to 4.0 x 10 ³ g/mol.

In a preferred embodiment 13 in the process according to any of the precedent embodiments for producing thermoplastic polyurethane, or one of their preferred embodiments, the compound reactive with isocyanate (b) preferably has a reactive group selected from the hydroxyl group, the amino group, the mercapto group or the carboxylic acid group. The preferred group is the hydroxyl group. These compounds are also referred to as polyols. In a preferred embodiment 14 in the process according to any of the precedent embodiments the polyol (b) preferably is se lected from the group consisting of polyesterol, polyetherol, polycarbonate diol, polysiloxane diol, polyalkylene diol, or is a mixture thereof, more preferred the polyol is selected from the group consisting of polyether polyol, and polycarbonate.

In a preferred embodiment 15 in the process to produce thermoplastic polyurethane according to any of the precedent embodiments, or one of their preferred embodiments, the polyol is poly ether polyol.

Polyester

In one preferred embodiment 16 of the process to produce thermoplastic polyurethane, as out lined herein before, the polyol is a polycaprolactone polyol or is a copolyesters based on adipic acid, succinic acid, pentanedioic acid, sebacic acid or mixtures thereof and 1 ,2-ethanediol and 1 ,3 propanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 3-methyl-pentanediol-1 ,5 and/or 1 ,6-hex- anediol, polytetrahydrofuran, or mixtures thereof. Particularly preferably the copolyester is based on adipic acid and mixtures of 1 ,2-ethanediol and 1 ,4-butanediol, or the polyester is based on adipic acid, succinic acid, pentanedioic acid, sebacic acid or mixtures thereof, and polytetramethylene glycol (PTHF), or mixtures thereof.

Polyether

In yet another embodiment 17 of the process for producing thermoplastic polyurethane de scribed herein for producing thermoplastic polyurethane, preferred polyols are polyether diols, further preferred are those based on ethylene oxide, propylene oxide and/or butylene oxide, pol- yetherpolyol with ethylen oxide and propylene oxide building blocks, polyethylene glycol; poly propylene glycol, polybutylene glycol, polytetrahydrofuran, polybutane diol, or is a mixture thereof, preferably the polyol is polytetrahydrofuran. Another preferred polyether in an embodment 17a comprising all the features of any of the prec edent embodiments, or one of their preferred embodiments, is polytetrahydrofuran (PTHF).

In a preferred embodiment 18 of the process for producing thermoplastic polyurethane de scribed herein, comprising all the features of any of the precedent embodimets, or their pre ferred embodiments, the number average molecular weight of the polyether is between 0,500 x 10 ³ g/Mol and 15 x 10 ³ g/Mol, preferred between 1 ,0 x 10 ³ g/Mol and 3,0 x 10 ³ g/Mol.

In a preferred embodiment 19 of the process described herein for producing thermoplastic poly urethane, comprising all the features of any of the precedent embodimets, or their preferred em bodiments, the polyol is a polyetherdiol being the reaction product of ethylene oxide and propyl ene oxide. In this polyetherdiol the ratio of ethylene oxide to propylene oxide is from 1 : 100 to 100 : 1 , preferably between 10 to 90 and 90 to 10, more preferably between 20 to 80 and 80 to 20, more preferably between 30 to 70 and 70 to 30, more preferably between 40 to 60 and 60 to 40, particularly preferably at 50 to 50.

In other preferred embodiment the ratio is 91 to 100 to 1 to 10, 81 to 90 to 1 1 to 20, 71 to 80 to 21 to 30, 61 to 70 to 31 to 40, 51 to 60 to 41 to 50, 41 to 50 to 51 to 60, 31 to 90 to 61 to 70, 21 to 30 to 71 to 80, 1 1 to 20 to 81 to 90, 1 to 10 to 91 to 100.

Polysioloxanediol

In a preferred embodiment 20 of the process described herein for producing thermoplastic poly urethane the polyol is a polysiloxane diol. The molecular weight is preferably between 0,500 x 10 ³ g/Mol and 15 x 10 ³ g/Mol, more preferred between 1 ,0 x 10 ³ g/Mol and 3,0 x 10 ³ g/Mol.

Preferably the oligo- or polysiloxane has the formula (I):

H0-[Ak-0]q-Ak-Si(R2)-[0-Si(R2)]p-0-Si(R ₂ )-Ak-[0-Ak] _q -0H formula (I) wherein Ak preferably represents C2-C4 alkylene, R represents C1-C4 alkyl, and each of p, q and q’ independently is a number selected from the range of 0 to 50. In more preferred moieties (B) of formula (I), p ranges from 1 to 50, especially from 2 to 50.

In one preferred embodiment Ak represents identical alkylene units in each residue (C1 ), in yet another preferred embodiment Ak represents different alkylene units in the same residue (C1 ).

In one preferred embodiment Ak is ethylene or propylene within the same residue (C1 ). One preferred polydimethylsiloxane diol has formula (II)

formula (II) with m in the range from 5 to 80,

or has formula (III)

formula (III).

Polyalkylene diol

In a preferred embodiment 21 of the process for producing thermoplastic polyurethane de scribed herein the polyol is polyaklylen diol, preferably based on butadiene.

Polyacarbonatdiol

In another preferred embodiment 22 of the process described herein for producing thermo plastic polyurethane the compounds (b) which is reactive towards isocyanates, is a polycar bonate diol, preferably an aliphatic polycarbonate diol. Preferred polycarbonate diols are, for ex ample, polycarbonate diols based on alkanediols. Preferred polycarbonate diols are strictly di functional OH-functional polycarbonate diols, preferably strictly difunctional OH-functional ali phatic polycarbonate diols. Preferred polycarbonate diols are based on butanediol, pentanediol or hexanediol, in particular 1 ,4-butanediol, 1 ,5-Pentanediol, 1 ,6-Hexanediol, 3-Methylpentane- (1 ,5)-diol, or are mixtures thereof, in particular preferably 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6- hexanediol, or mixtures thereof. Most preferred in the present invention are polycarbonate diols based on butanediol and hexanediol, polycarbonate diols based on pentanediol and hexanediol, polycarbonate diols based on hexanediol, and mixtures of two or more of these polycarbonate diols.

Preferably, the polycarbonate diols used have a number average molecular weight Mn in the range from 0.5 x 10 ³ to 4.0 x 10 ³ g/mol, determined via GPC, preferably in the range from 0.65 x 10 ³ g / mol to 3.5 x 10 ³ g/mol determined via GPC, particularly preferred in the range from 0.8 x 103 g/mol to 3.0 x 10 ³ g/mol, determined via GPC.

Mixture of polyol

In one preferred embodiment the polyol is a mixture of two or more polyols. In other preferred embodiment the polyol is only one polyol. Only one polyol means that the polyol comprises at least 70 wt%, more preferably 80 wt%, more preferred 90 wt%, more preferred 95 wt% and most preferred at least 99 wt% of that one polyol.

Chain extender

In a preferred embodiment 23 in the syntheses of the thermoplastic polyurethane for the pro cess according to this invention, comprising all the features of any of the precedent embod- imets, or their preferred embodiments, beside the polyol and isocyanate a chain extender (c) is used. The chain extender is preferably an aliphatic, araliphatic, aromatic and/or cycloaliphatic compound with a molecular weight of 0.05 x 10 ³ g/mol to 0.499 x 10 ³ g/mol, preferably with 2 groups reactive with isocyanate, which are also referred to as functional groups. The chain ex tender is either a single chain extender or a mixture of at least two chain extenders.

In a preferred embodiment a chain extender (c) is used for the synthesis of the polyisocyanate polyaddition product, preferably the thermoplastic polyurethane. The chain extender is prefera bly aliphatic, araliphatic, aromatic and/or cycloaliphatic compounds with a molecular weight of 0.05 x 10 ³ g/mol to 0.499 x 10 ³ g/mol, preferably with 2 groups reactive with isocyanate, which are also referred to as functional groups. In preferred embodiments the chain extender is either a single chain extender or a mixture of at least two chain extender.

The chain extender is preferably a difunctional compound. Preferred examples being diamines or alkanediols having 2 to 10 carbon atoms in the alkylene radical.

In a preferred embodiment 24 the chain extender (c) is selected from the group consisting of

1 .2-ethylene glycol, 1 ,2-propanediol, 1 ,3-propanediol, 1 ,4-butanediol, 2,3-butanediol, 1 ,5-pen- tanediol, 1 ,6-hexanediol, diethylene glycol, dipropylene glycol, 1 ,4-cyclohexanediol, 1 ,4-di methanol cyclohexane, neopentylglycol and hydroquinone bis (beta-hydroxyethyl) ether (HQEE), di-, tri-, tetra-, penta-, hexa-, hepta-, okta-, nona- and/or deca alkylene glycole, prefera bly respective oligo- and/or polypropylene glycole, or is a mixture thereof.

More preferably the chain extender is selected from the group consisting of 1 ,2-ethylene glycol,

1 .3-propanediol, 1 ,4-butanediol, and 1 ,6-hexanediol are particularly suitable.

Particularly preferred chain extender is a mixture of 1 ,4-butanediol and 1 ,3-propanediol. In pre ferred embodiments the ratio of 1 ,4-butanediol to 1 ,3-propanediol is between 6 : 1 and 10 to 1 .

Catalyst

In a preferred embodiment 25 a catalyst (d) is used with the build-up components in the process producing thermoplastic polyurethane as described herein. This catalyst is in particular a cata lysts which accelerates the reaction between the NCO groups of the isocyanates (a) and the isocyanate-reactive compound (b), preferably with hydroxyl groups and, if used, the chain ex tender (c).

Preferred catalysts are selected from the group consisting of tertiary amines, especially triethyl- amine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylami- noethoxy)-ethanol, diazabicyclo-(2,2,2)-octane. In another preferred embodiment, the catalysts are organic metal compounds such as titanium acid esters, iron compounds, preferably ferric acetylacetonate, tin compounds, preferably those of carboxylic acids, particularly preferred tin diacetate, tin dioctoate, tin dilaurate or tin dialkyl salts, further preferred dibutyltin diacetate, dibutyltin dilaurate, or bismuth salts of carboxylic acids, preferably bismuth decanoate, or is a mixture thereof.

Particularly preferred catalysts is selected from the group consisting of tin dioctoate, bismuth decanoate, titanic acid esters, or is a mixture thereof.

Most preferred the catalyst is tin dioctoate.

The catalyst (d) is preferably used in quantities of 0,0001 to 0,1 parts by weight per 100 parts by weight of the composition.

Auxiliary

In a preferred embodiment 26 an auxiliary or additive (e) is added to the polymer, in the pre ferred embodiment of thermoplastic polyurethane, in another preferred embodiment to the build ing components (a) to (c) in the synthesis of the thermoplastic polyurethane. Preferred exam ples include surface-active substances, fillers, flame retardants, nucleating agents, oxidation stabilizers, lubricating and demolding aids, dyes and pigments, if necessary stabilizers, prefera bly against hydrolysis, light, heat or discoloration, inorganic and/or organic fillers, reinforcing agents and/or plasticizers.

Stabilizers in the sense of this invention are additives which protect a plastic or a plastic compo sition against harmful environmental influences. Preferred examples are primary and secondary antioxidants, sterically hindered phenols, hindered amine light stabilizers, UV absorbers, hydrol ysis inhibitors, quenchers and flame retardants. Examples of commercial stabilizers are given in Plastics Additives Handbook, 5th Edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001 ([1 ]), P-98-S136.

In a preferred embodiment, the UV absorber has a number average molecular weight greater than 0.3 x 10 ³ g/Mol, in particular greater than 0.39 x 10 ³ g/Mol. Furthermore, the preferred UV absorber has a molecular weight not exceeding 5 x 10 ³ g/Mol, particularly preferred not exceed ing 2 x 10 ³ g/mol.

The UV absorber is preferably selected from the group consisting of cinnamates, oxanilides and benzotriazole, or is a mixture thereof, particularly suitable as UV absorbers is benzotriazole. Ex amples of particularly suitable benzotriazoles are Tinuvin® 213, Tinuvin® 234, Tinuvin® 312, Tinuvin® 571 , Tinuvin® 384 and Eversorb® 82.

Preferably the UV absorbers is added in quantities of 0.01 wt.% to 5 wt.% based on the total weight of the compositon, preferably 0.1 wt.% to 2.0 wt.%, in particular 0.2 wt.% to 0.5 wt.%.

Often a UV stabilization based on an antioxidant and a UV absorber as described above is not sufficient to guarantee a good stability of the composition against the harmful influence of UV rays. In this case, in addition to the antioxidant and/or the UV absorber, or as single stabilizer, a hindered-amine light stabilizer (HALS) is be added to the composition.

Examples of commercially available HALS stabilizers can be found in Plastics Additive Hand book, 5th edition, H. Zweifel, Hanser Publishers, Munich, 2001 , pp. 123-136.

Particularly preferred hindered amine light stabilizers are bis-(1 ,2,2,6, 6-penta-methylpiperidyl) sebacat (Tinuvin® 765, Ciba Spezialitatenchemie AG) and the condensation product of 1 -hy- droxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid (Tinuvin® 622). In particu lar, the condensation product of 1 -hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidines and succinic acid (Tinuvin® 622) is preferred, if the titanium content of the finished product is less than 150 ppm, preferably less than 50 ppm, in particular less than 10 ppm, based on the com ponents used.

HALS compounds are preferably used in a concentration of from 0.01 wt.% to 5 wt.%, particu larly preferably from 0.1 wt.% to 1 wt.%, in particular from 0.15 wt.% to 0.3 wt.%, based on the total weight of the compositon.

A particularly preferred UV stabilization contains a mixture of a phenolic stabilizer, a benzotria zole and a HALS compound in the preferred amounts described above.

Further information on the above-mentioned auxiliaries and additives can be found in the tech nical literature, e.g. Plastics Additives Handbook, 5th edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001 . Production Process

The polyisocyanate polyaddition product, preferably the thermoplastic polyurethane can be pro duced discontinuously or continuously according to the known processes, e.g. using reaction extruders, using the belt process, and applying the“one shot” process or the prepolymer pro cess, preferably the "one-shot" process. In the "one-shot" process, the building components (a), (b), and eventually the chain extender (c) which come to the reaction are mixed with each other. This is done either in succession or simultaneously, in preferred embodiment in the presence of the catalyst (d) and/or auxiliary (e). In the extruder process, the building components (a), (b) eventually the chain extender (c) and, in preferred forms, also the catalyst (d) and/or the auxil iary (e) are mixed. The mixing is done preferably at temperatures between 100°C and 280°C, preferably between 140°C and 250°C. The polyurethane obtained preferably is in the form of a granulate or a powder.

The auxiliaries in one embodiment are added during synthesis of the polyisocyanate polyaddi tion product, preferably the thermoplastic polyurethane. In another preferred embodiment the auxiliary (e) is added to the polyisocyanate polyaddition product, preferably the thermoplastic polyurethane after its synthesis, preferably in an extruder.

The mixture comprising the polyisocyanate polyaddition product, preferably the thermoplastic polyurethane eventually at least one auxiliary and in preferred embodiments further polymers is also referred to as composition

A twin-screw extruder is preferred, as the twin-screw extruder operates with positive conveying and thus allows a more precise setting of the temperature and output quantity on the extruder.

Process for producing the film

One preferred embodiment 27 is the process according to any of the precedent embodiments, respectively its further preferred embodiments, wherein the volatile substance is a powder. Therefore the volatile substance is milled. In one preferred embodiment it is dispersed in the polymer, preferably the thermoplastic polyurethane, either during its production process, or more preferred it is added to the final polymer respectively the composition comprising the poly mer. In another preferred embodiment the powder is dissolved or dispersed in the solvent. This is done before of after the compsosition is dissolved or dispersed in the solvent. The milled par ticles of the volatile substance, also referred to as powder, preferable have the maximum diam eter of the pores as desired, preferably this diameter is in the range of from 0.001 mm to 5 mm, preferably 0.001 mm to 1 mm, more preferably between 0.001 mm and 0.8 mm, even more pre ferred between 0.001 mm and 0.1 mm. In another preferred embodiment the maximal particle size of the powder of the volatile sub stance is less than the thickness of the film. Further preferred the particle size is 50 % to 95 % of the thickness of the film, more preferable 70 % - 90 %.

Solvent

Another preferred embodiment 28 is the process according to any of the precedent embodi ments, respectively its further preferred embodiments, wherein the polymer composition is dis solved in a solvent and the volatile substance is homogeneously dispersed in the solvent com prising the composition, before the composition is formed to the film.

The solvent in a preferred embodiment has a boiling point of less than 1 10°C, preferably less than 80°C. In another preferred embodiment this solvent is mixable with water, preferably with a content of water from 0 wt% to 20 wt% referring to whole amount of water and solvent.

In the process according to any of the precedent embodiments respectively its preferred em bodiments, the solvent preferably is selected from the group consisting of tetrahydrofuran (THF), methyl ethyl ketone (MEK), diethyl ketone, diacetyl ketone, ethyl acetate, methyl acetate, acetone, or is a mixture thereof. Most preferred is tetrahydrofuran (TFIF) These solvents as well as the the very preferred tetrahydrofuran (TFIF) in a further preferred embodiment are used for the process in which the polymer is thermoplastic polyurethane

Production process of the membrane

In one preferred embodiment 29 of the process according to any of the precedent embodiments the composition comprising the polymer, which is preferably thermoplastic polyurethane, and in a preferred embodiment the volatile substance, in a first step are dissolved and/or dispersed in a solvent and this solution or dispersion is then homogeneously spread on a surface where the solvent and the volatile substance are then removed and the film with the pores remains. In one preferred embodiment the surface is even and in a m ore preferred embodiment is a panel, e.g. from glas, metal, or procelan. In another preferred embodiment the composition comprising the polymer, preferably the thermoplastic polyurethane, is dissolved or dispersed in the solvent (so lution 1 ) and the the volatile substance is then dissolved or dispersed in this solution 1 resulting in a solution 2. This solution 2 is then homogeneously spread on a surface.

In one preferred embodiment the solution comprising the composition and the volatile sub stance is spread on an flat surface over which a blade is moving continuously with a defined gap between the blade and the surface. This process is also referred to as doctor blading. The solution thus spreads on the surface to form a thin layer, also referred to as pre-film, which re sults in a film upon drying. The temperature of the surface must be below of the decomposition or evaporation temperature Tv of the volatile substance. The solvent is evaporated at room or elevated temperature Ts, which preferably has to be below the decomposition or evaporation temperature TV of the volatile substance. After the solvent is removed, preferably in a first step, the resulting film is thermally treated to remove, preferably to decompose the volatile substance and producing the film with pores. This process is also referred to as two heating steps process. In another preferred embodiment the pressure is reduced to remove the solvent or the volatile substance, or both. In another preferred embodiment elevation of temperature is combined with reducing pressure to remove the solvent or the volatile substance, or both.

It is also possible to remove the solvent and volatile substance in one heating step process, e.g. after doctor blading, however the two heating steps process is preferred. The two heating step process results in a better water resistance and vapour permeability compared to the one heat ing step.

In another preferred embodiment the film with pores is produced in a continuous process. This continuous process also comprises all preferred embodiments as outlines for the doctor blading outlined above.

In a preferred embodiment the continuous process is wet casting. The solution of the composi tion comprising the polymer and the volatile substance is precipitated in a bath. The precipitat ing preverably is done by reversal of the chemical reaction with which the polymer was dis solved.

Another preferred embodiment is the dry casting process. In the dry casting process the solvent is evaporated and the composition comprising the polymer recoveres as a film. Preferably a band- or drum casting machine is used. Also in this process the two heating step process is pre ferred.

The solution flows from a reservoir with adjustable slot without pressure and bubbles under a drum (drum casting) or an endless strip (band casting), where the band preferably is made of copper or steel.

In another embodiment the solven is spread evenly with an doctor blade. Preferably the doctor blade is adjusted controlled electronically. The thickness can be precisely controlled by laser measurement. The solvent evaporates from the material during film formation. The film passes through a dry ing zone. After the film is ried the volatile substance is removed by a further heating step. Finally the film with pores it is removed from the drum or circulating belt with a scraper.

Cast foils are very homogeneous, free of bubbles and shrinkage.

Film

Another aspect of this invention is the porous film produced according to any of the precedent embodiments of the process.

Membrane / Pore size

In a preferred embodiment of this invention the film, preferably the porous film, shall be prefera bly understood as membrane, preferably with a thickness of from 1 pm to 1 mm, more prefera bly from 5 pm to 100 pm, more preferably from 20 pm to 80 pm, in particular from 30 pm to 60 pm.

This membrane preferably is semipermeable structure capable of separating two fluids or sepa rating molecular and/or ionic components or particles from a liquid. A membrane acts as a se lective barrier, allowing some particles, substances or chemicals to pass through, while retain ing others.

Preferably membranes are reverse osmosis (RO) membranes, forward osmosis (FO) mem branes, nanofiltration (NF) membranes, ultrafiltration (UF) membranes or microfiltration (MF) membranes, or is a semipermeable membrane (SM). Most preferre is a semipermeable mem brane, which more preferably is water resistant and vapour permeable.

In a preferred embodiment the membrane according to the present invention has pores with an average pore diameter in the range of from 0.001 pm to 0.8 pm, preferably 0.002 pm to 0.5 pm determined using Fig porosimetry according to DIN 66133.

The pore size distribution within the membranes according to the present invention preferably is not homogenous but the membrane comprises pores with different pore sizes. Preferably, the pore size distribution has a gradient over the diameter of the membrane. A gradient over the di ameter of the membrane in the context of the present invention is to be understood in the way that the pores on one surface of the membrane or close to said surface have an average pore diameter which is different from the average pore diameter of the second surface or close to said second surface of the membrane.

The composition and the properties of the membrane can be varied depending on the applica tion. For example, the thickness of the membrane can be varied in a wide range. Preferably the membrane has a thickness in the range from 5 to 100 pm, more preferably in the range from 20 to 80 pm, in particular in the range from 30 to 60 pm.

Thus, according to a further embodiment, the present invention is also directed to a membrane as disclosed above, wherein the membrane has a thickness in the range from 5 to 100 pm.

Use

The film with pores also referred to as membranes show high liquid entry pressures (LEP, measured according to DIN EN 2081 1 ) and good water vapor permeability values (WDD, meas ured according to DIN 53122). In apreferred embodiment the membrane has a liquid entry pres sure, measured according to DIN EN 2081 1 , in the range of 1 bar to 5 bar, preferably 3 bar to 4 bar.

Thus, according to a further embodiment, the present invention is also directed to a membrane as disclosed above, wherein the membrane has a liquid entry pressure in the range of 1 to 5 bar.

According to the process of the present invention, a porous film is obtained which can be used as a membrane. The process of the present invention can also comprise further steps, for ex ample washing steps or a temperature treatment.

The film or membrane obtained or obtainable according to the process of the present invention is stable and has advantageous properties such as high liquid entry pressures (LEP, measured according to DIN EN 2081 1 ) and good water vapor permeability values (WDD, according to DIN 53122). Thus, the membranes according to the present invention are particularly suitable for ap plications which require a high permeability for vapor such as in functional wear.

The membranes according to the present invention can be used as a coating layer for a woven article, can be directly used as rain protection wearing, or as a filter, preferably for industrial or medical use.

According to a further aspect, the present invention is also directed to the use of a membrane as disclosed above or a membrane obtained or obtainable according to a process as disclosed above for water protection wearing, coating of a woven article, or as a filter, preferably for indus trial or medical use. Preferably the membrane according to the present invention can be used for example in outer wear, sportswear for example for sailing, hiking or skiing, rainwear, protective wear such as trousers, jackets, shoes, especially shoe uppers, gloves, hats, caps. Furthermore, the mem branes according to the present invention can be used for example in protective covers, for tents, backpacks, umbrellas or for example in applications for automotives such as covers and tops for convertibles.

The present invention also concerns the use of the film produced by the process as outlined abovethe manufacture of applications selected from, coating, damping element, bellows, foil, fibre, moulded body, flooring for buildings and transport, non woven fabric, preferably gasket, roll, shoe sole, hose, cable, cable connector, cable sheathing, pillow, laminate, profile, strap, saddle, foam, by additional foaming of the preparation, plug connection, trailing cable, solar module, lining in automobiles, wiper blade, elevator load bearing members, roping arrange ments, drive belts for machines, preferably passenger conveyer, handrails for passenger con veyers modifier for thermoplastic materials, , which means substance that influences the proper ties of another material. Each of these uses itself is a preferred form, also referred to as an ap plication.

The applications are preferably manufactured by injection moulding, calendering, powder sinter ing, or extrusion.

Yet another aspect of this invention is the use of a volatile substance for porous film, preferably according to the film derived from the process as described in one of the embodiments herein.

It is understood that the features of the subject matter/method/uses of the invention, as eluci dated below and as stated above, can be used not only in the particular combination specified but also in other combinations as well, without departing the scope of the invention. Accordingly, for example, the combination of a preferred feature with a more preferred feature, or of an oth erwise uncharacterized feature with a very preferred feature, etc., is implicitly comprised, even if that combination is not expressly mentioned.

Examples

1. Example - Recipe of the polymer (TPU-1 )

mass [g]

polyethyleneglycol (Mw 1500 g/mol) 1000

Diphenylmethane disocyanate (MDI) 720

1 ,4-butanediol 175

1 ,3-propanediol 21

Licowax E Flake ® 3

(Montanic acid ester wax)

2. Example - Mixtures of sluries for producing the film

Slurry 1 : 10 wt% TPU-1 solved in tetrahydrofurane (THF)

Slurry 2: 10 wt% TPU-1 solved in tetrahydrofurane (THF), with 10 wt% ammonium bicar bonate referring to the weight of TPU-1

Slurry 3: 10 wt% TPU-1 solved in tetrahydrofurane (THF), with 20 wt% ammonium bicar bonate referring to the weight of TPU-1

Slurry 4: 10 wt% TPU-1 solved in tetrahydrofurane (THF), with 30 50 wt% ammonium bi carbonate referring to the weight of TPU-1

Slurry 5: 10 wt% TPU-1 solved in tetrahydrofurane (THF), with 40 100 wt% ammonium bi carbonate referring to the weight of TPU-1

3. Example - Producing the TPU film

To a 10 wt% solution of the thermoplastic polyurethane (TPU-1 ) in tetrahydrofurane (THF - sol vent), ammonium bicarbonate as volatile (particle size 0.01 -0.5 mm) substance was added and this mixture was stirred for 20 minutes to become a slurry. The slurry was coated on an even glass surface at room temperature via doctor blading with a thickness of 0,05 mm. In the doctor blading process, the slurry was placed beyond the doctor blade. The blade is moving continu ously on the surface of the glass with a defined gap between the blade and the glass surface. The slurry spreads on the substrate to form a thin sheet which results in a film-layer upon dry ing. The temperature of the glass surface must be below of the decomposition temperature of volatile substance. After 12 hrs, the solvent is evaporated at 50 °C until the film became stable.. After the film is stable it was thermally treated (80°C for 3 hrs) to decompose the ammonium bi carbonate. After heat treatment small voids and cracks are visible under Microscope and a permeability measurement shows improvement of vapor permeation compared to the original TPU-Film.

The following table gives the vapor and water permeability of the films produced from slurry 1 to 5

Table 1 : Comparison of vapor and water permeability of the films

4. Example - Thermogravimetric Analysis (TGA)

The TGA is measured according to DIN EN ISO 1 1385. The TGA-device is a Mettler Teldo TGA/SDTA 851 e and the device is firstly flowed by nitrogen for 30 minutes to achieve a pure nitrogen atmosphere in the sample cavity. Then the sample is heated up with a rate of 5 K/min and weight loss will be measured continuously. To define the decomposition temperature the 1 st derivative of the weight loss curve, which indicates the point of greatest rate of change on the weight loss curve. In the Experiment the respective function of the apparate is used.

5. Example-recipe of the polymer (TPU-2) mass [g]

Polyetetrahydrofuran (Mw 1000 g/mol) 1000

Diphenylmethane disocyanate (MDI) 630

1 ,4-butanediol 136,74 6. Example - Mixtures of sluries for producing the film

Slurry 6: 10 wt% TPU-2 solved in tetrahydrofurane (THF), with 100 wt% ammonium bicar bonate referring to the weight of the TPU-2

7. Example - Producing the film

To a 10 wt% solution of the thermoplastic polyurethane TPU-2 in tetrahydrofurane (THF - solvent),

10 wt% of ammonium bicarbonate (AC) as volatile substance (particle size 0.01 - 0.5 mm) was added and this mixture was stirred for 20 minutes to become a slurry. The slurry 6 was coated on an even glass surface at room temperature via doctor blading with a thickness of 0,05 mm. In the doctor blading process, the slurry was placed beyond the doctor blade. The blade is moving continuously on the surface of the glass with a defined gap between the blade and the glass surface. The slurry spreads on the substrate to form a thin sheet which results in a film-layer upon drying. The tempera ture of the glass surface must be below of the decomposition temperature of volatile substance am monium bicarbonate. After 12 hrs, the solvent is evaporated at 50 °C until the film became stable. After the film is stable it was thermally treated (100°C for 6 hrs) to decompose the ammonium bicar bonate. As comparison the same film (TPU-2+AC) was stored in a water bath to remove the ammo nium bicarbonate by water and as second comparison the film was generated with TPU-2 without ammonium carbonate. The vapor permeabilities of all these three films were meseared and illus trated in Tab. 2.

Table 2 -

The film with thermal treatment shows much better vaour permeability than with water treatment.