METHOD FOR WELDING MEMBRANES

Abstract

A process for welding porous membranes, the process containing i) providing first and second porous membranes; ii) at least partially superimposing the first and second porous membranes to obtain an at least partial superimposition region; iii) welding the first and second porous membranes at least in a portion of the at least one superimposition region at a temperature in the range from 100 to 300 C. to obtain an at least partially welded composite of the first and second porous membranes, wherein the first and second porous membranes are made of at least one thermoplastic elastomer selected from the group consisting of a polyurethane elastomer, a polyester elastomer, a polyetherester elastomer, a polyesterester elastomer, a polyamide elastomer, a polyetheramide elastomer, a polystyrene elastomer, and an ethylene-vinyl acetate elastomer, and wherein the first and second porous membranes have pores having an average pore diameter of less than 2000 nm.

Claims

1-15. (canceled)

16: A process for welding porous membranes, the process comprising: i) providing a first porous membrane and a second porous membrane; ii) at least partially superimposing the first and second porous membranes to obtain an at least partial superimposition region; iii) welding the first and second porous membranes at least in a portion of the at least one superimposition region at a temperature in the range from 100 to 300 C. to obtain an at least partially welded composite of the first and second porous membranes; wherein a material of the first and second porous membranes comprises at least one thermoplastic elastomer selected from the group consisting of a polyurethane elastomer, a polyester elastomer, a polyetherester elastomer, a polyesterester elastomer, a polyamide elastomer, a polyetheramide elastomer, a polystyrene elastomer, and an ethylene-vinyl acetate elastomer, and wherein the first and second porous membranes have pores having an average pore diameter of less than 2000 nm, determined by means of Hg porosimetry in accordance with DIN 66133.

17: The process according to claim 16, wherein the welding is carried out for a period of time in the range from 0.1 seconds to 10 minutes.

18: The process according to claim 16, wherein the welding is carried out under an atmosphere selected from protective gas, air and lean air.

19: The process according to claim 16, wherein the welding is carried out at a pressure in the range from 1 to 10 bar.

20: The process according to claim 16, wherein the welding is carried out at a temperature in the range from 150 to 250 C.

21: The process according to according to claim 16, wherein the first porous membrane has an average thickness in the range from 5 to 150 m.

22: The process according to according to claim 16, wherein the first porous membrane has pores having an average pore diameter in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133.

23: The process according to claim 16, wherein the material of the first porous membrane comprises a polyurethane elastomer based on the following components: 80% to 100% by weight of a mixture of at least one diol (D1) and at least one isocyanate (I1), 0 to 20% by weight of at least one compound (C1) having at least two isocyanate-reactive groups; and wherein the first porous membrane has pores having an average pore diameter in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133.

24: The process according to claim 16, wherein the second porous membrane has an average thickness in the range from 5 to 150 m and/or has pores having an average pore diameter tin the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133.

25: The process according to claim 24, wherein the material of the first porous membrane and the material of the second porous membrane comprise the same thermoplastic elastomer.

26: A welded composite of a first porous membrane and a second porous membrane, obtained by the process according to claim 16.

27: The welded composite according to claim 26, wherein a water vapor permeability (WVP) at 38 C. and 90% relative humidity according to DIN 53122 is more than 1000 [g/m.sup.2*d] and/or a water tightness (LEP) is greater than 2 bar, determined according to DIN EN 20811.

28: An article, comprising: the welded composite according to claim 26, wherein the article comprises clothing, a shoe, a boot, protective clothing, a tent and a tarpaulin.

Description

DESCRIPTION OF THE FIGURE

[0134] FIG. 1 shows an SEM image of the cross-sectional area of the welded composite (membrane composite) in the area of the weld seam.

[0135] The present invention is illustrated further by the following embodiments and combinations of embodiments as indicated by the corresponding references and back-references. In particular, it should be emphasized that in every instance where a range of embodiments is given, for example in the context of an expression such as the process according to any of embodiments 1 to 4, each embodiment in this range is deemed to be explicitly disclosed to those skilled in the art, i.e. the meaning of this expression is to be understood by those skilled in the art as synonymous with the process according to any of embodiments 1, 2, 3, and 4.

[0136] 1. A process for welding porous membranes, comprising: [0137] i) providing a porous membrane and a sheetlike support material; [0138] ii) at least partially superimposing porous membrane and sheetlike support material as per i) to obtain an at least partial superimposition region; [0139] iii) welding porous membrane and support material at least in a portion of the superimposition region as per ii) at a temperature in the range from 100 to 300 C., preferably in the range from 150 to 250 C., to obtain an at least partially welded composite of porous membrane and sheetlike support material. [0140] 2. The process according to embodiment 1, wherein the welding as per iii) is effected for a period of time in the range from 0.1 seconds to 10 minutes, preferably in the range from 0.5 seconds to 60 seconds, more preferably in the range from 1 to 10 seconds. [0141] 3. The process according to either of embodiments 1 and 2, wherein the welding as per iii) is effected under an atmosphere selected from protective gas, especially argon or nitrogen, air or lean air, preferably under air. [0142] 4. The process according to any of embodiments 1 to 3, wherein the welding as per iii) is effected at a pressure in the range from 1 to 10 bar, preferably in the range from 2 to 8 bar, more preferably in the range from 3 to 5 bar. [0143] 5. The process according to any of embodiments 1 to 4, wherein the welding as per iii) is effected at a temperature in the range from 150 to 250 C. [0144] 6. The process according to any of embodiments 1 to 5, wherein the porous membrane has an average thickness in the range from 5 to 150 m, preferably in the range from 50 to 100 m, more preferably in the range from 70 to 90 m. [0145] 7. The process according to any of embodiments 1 to 6, wherein the porous membrane has pores having an average pore diameter of less than 2000 nm, preferably in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0146] 8. The process according to any of embodiments 1 to 7, wherein the material of the porous membrane comprises a thermoplastic elastomer, preferably selected from the group consisting of polyurethane elastomer, polyester elastomer, polyetherester elastomer, polyesterester elastomer, polyamide elastomer, polyetheramide elastomer, polystyrene elastomer, ethylene-vinyl acetate elastomer and mixtures of two or more of these elastomers, preferably polyurethane elastomer. [0147] 9. The process according to embodiment 8, wherein the material of the porous membrane comprises a polyurethane elastomer based on the following components: [0148] 80% to 100% by weight of a mixture of at least one diol (D1) and at least one isocyanate (I1), [0149] 0 to 20% by weight of at least one compound (C1) having at least two isocyanate-reactive groups; and wherein the porous membrane has pores having an average pore diameter in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0150] 10. The process according to embodiment 9, wherein the material of the porous membrane comprises a further polyurethane (PU2) based on at least one polyol (P2), at least one diol (D2) and at least one polyisocyanate (I2). [0151] 11. The process according to embodiment 9 or 10, wherein the compound (C1) is a polyol, preferably selected from the group of the divalent radicals of an oligosiloxane or polysiloxane of general formula I

-[Ak-O].sub.q-Ak-Si(R.sub.2)[OSi(R.sub.2)].sub.pOSi(R.sub.2)-Ak-[O-Ak].sub.q-(I) [0152] where Ak is C.sub.2-C.sub.4 alkylene and R is C.sub.1-C.sub.4 alkyl and each of p, q and q is independently a number in the range from 0-50, with p more preferably being a number in the range from 1 to 50, more preferably in the range from 2 to 50. [0153] 12. The process according to any of embodiments 9 to 11, wherein the diol (D1) is selected from the group consisting of ethanediol, butanediol and hexanediol. [0154] 13. The process according to any of embodiments 9 to 12, wherein the polyisocyanate is selected from the group consisting of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI). [0155] 14. The process according to any of embodiments 1 to 13, wherein the support material comprises a second porous membrane, the material of the second porous membrane comprising a thermoplastic elastomer selected from the group consisting of polyurethane elastomer, polyester elastomer, polyetherester elastomer, polyesterester elastomer, polyimide elastomer, polyetheramide elastomer, polystyrene elastomer, ethylene-vinyl acetate elastomer and mixtures of two or more of these elastomers, preferably polyurethane elastomer. [0156] 15. The process according to embodiment 14, wherein the second porous membrane has an average thickness in the range from 5 to 150 m, preferably in the range from 50 to 100 m, more preferably in the range from 70 to 90 m. [0157] 16. The process according to either of embodiments 14 and 15, wherein the second porous membrane has pores having an average pore diameter of less than 2000 nm, preferably in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0158] 17. The process according to any of embodiments 14 to 16, wherein the material of the porous membrane as per i) and that of the second porous membrane comprise the same thermoplastic elastomer, preferably the same polyurethane elastomer. [0159] 18. A welded composite of a porous membrane and a support material, obtained or obtainable by the process according to any of embodiments 1 to 17. [0160] 19. The welded composite according to embodiment 18, wherein the water vapor permeability (WVP) at 38 C. and 90% relative humidity according to DIN 53122 is more than 1000 [g/m.sup.2*d]. [0161] 20. The welded composite according to embodiment 18 or 19, wherein the watertightness (LEP) is greater than 2 bar and preferably is in the range from 2 to 5 bar, more preferably in the range from 3 to 4 bar, determined according to DIN EN 20811. [0162] 21. A welded composite of a porous membrane and a support material, wherein the porous membrane has an average thickness in the range from 5 to 150 m, preferably in the range from 50 to 100 m, more preferably in the range from 70 to 90 m. [0163] 22. The welded composite according to embodiment 21, wherein the porous membrane has pores having an average pore diameter of less than 2000 nm, preferably in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0164] 23. The welded composite according to embodiment 21 or 22, wherein the material of the porous membrane comprises a thermoplastic elastomer, preferably selected from the group consisting of polyurethane elastomer, polyester elastomer, polyetherester elastomer, polyesterester elastomer, polyamide elastomer, polyetheramide elastomer, polystyrene elastomer, ethylene-vinyl acetate elastomer and mixtures of two or more of these elastomers, preferably polyurethane elastomer. [0165] 24. The welded composite according to embodiment 23, wherein the material of the porous membrane comprises a polyurethane elastomer based on the following components: [0166] 80% to 100% by weight of a mixture of at least one diol (D1) and at least one isocyanate (11), [0167] 0 to 20% by weight of at least one compound (C1) having at least two isocyanate-reactive groups; and wherein the porous membrane has pores having an average pore diameter in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0168] 25. The welded composite according to embodiment 24, wherein the material of the porous membrane comprises a further polyurethane (PU2) based on at least one polyol (P2), at least one diol (D2) and at least one polyisocyanate (I2). [0169] 26. The welded composite according to embodiment 24 or 25, wherein the compound (C1) is a polyol, preferably selected from the group of the divalent radicals of an oligosiloxane or polysiloxane of general formula I

-[Ak-O].sub.q-Ak-Si(R.sub.2)[OSi(R.sub.2)].sub.pOSi(R.sub.2)-Ak-[O-Ak].sub.q-(I) [0170] where Ak is C.sub.2-C.sub.4 alkylene and R is C.sub.1-C.sub.4 alkyl and each of p, q and q is independently a number in the range from 0-50, with p more preferably being a number in the range from 1 to 50, more preferably in the range from 2 to 50. [0171] 27. The welded composite according to any of embodiments 24 to 26, wherein the diol (D1) is selected from the group consisting of ethanediol, butanediol and hexanediol. [0172] 28. The welded composite according to any of embodiments 24 to 27, wherein the polyisocyanate is selected from the group consisting of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI). [0173] 29. The welded composite according to any of embodiments 24 to 28, wherein the support material comprises a second porous membrane, the material of the second porous membrane comprising a thermoplastic elastomer selected from the group consisting of polyurethane elastomer, polyester elastomer, polyetherester elastomer, polyesterester elastomer, polyimide elastomer, polyetheramide elastomer, polystyrene elastomer, ethylene-vinyl acetate elastomer and mixtures of two or more of these elastomers, preferably polyurethane elastomer. [0174] 30. The welded composite according to embodiment 29, wherein the second porous membrane has an average thickness in the range from 5 to 150 m, preferably in the range from 50 to 100 m, more preferably in the range from 70 to 90 m. [0175] 31. The welded composite according to either of embodiments 29 and 30, wherein the second porous membrane has pores having an average pore diameter of less than 2000 nm, preferably in the range from 0.001 m to 0.8 m, determined by means of Hg porosimetry in accordance with DIN 66133. [0176] 32. The welded composite according to any of embodiments 29 to 31, wherein the material of the porous membrane as per i) and that of the second porous membrane comprise the same thermoplastic elastomer, preferably the same polyurethane elastomer. [0177] 33. The welded composite according to any of embodiments 21 to 32, wherein the water vapor permeability (WVP) at 38 C. and 90% relative humidity according to DIN 53122 is more than 1000 [g/m.sup.2*d]. [0178] 34. The welded composite according to any of embodiments 21 to 33, wherein the watertightness (LEP) is greater than 2 bar and preferably is in the range from 2 to 5 bar, more preferably in the range from 3 to 4 bar, determined according to DIN EN 20811. [0179] 35. The use of a welded composite according to any of embodiments 18 to 20 or of a welded composite according to any of embodiments 21 to 34 for the production of an article selected from the group consisting of clothing, shoes, boots, protective clothing, tents and tarpaulins.

CITED LITERATURE

[0180] U.S. Pat. No. 3,953,566, [0181] U.S. Pat. No. 3,962,153 [0182] U.S. Pat. No. 5,562,977 [0183] JP 5005276 [0184] US 2015/0230563 [0185] Kunststoffhandbuch [Plastics Handbook], 7, Polyurethane [Polyurethanes], Carl Hanser Verlag, 3rd edition 1993, section 3.1 [0186] Kunststoffhandbuch [Plastics Handbook], 7, Carl Hanser Verlag, 1966, pages 103-113.

EXAMPLES

[0187] The following examples serve to illustrate the invention, but are not restrictive with respect to the subject matter of the invention.

[0188] 1. Preparation of the Polyurethane (Hard Phase)

[0189] 1.1 Substances

[0190] The following substances were used:

TABLE-US-00001 Molecular weight Abbreviation Compound [g/mol] Iso 1 4,4-methylenediphenylene 250.26 g/mol diisocyanate CE 2 butane-1,4-diol 90.12 g/mol

[0191] 1.2 Synthesis of the Polyurethane (Hard Phase Type 1)

[0192] Chain extender CE2 was dispensed into a 2 l can. Isocyanate Iso1 was subsequently added under gentle stirring and the reaction was carefully heated to 70 C. under air. The mixture was then stirred until a temperature of 90 C. was reached. The reaction mixture was poured into a flat dish and heated at 125 C. for 10 minutes on a hotplate. The slab obtained was heat-treated in a heating oven at 80 C. for 15 minutes.

[0193] The material obtained was cut into pieces and ground to give pellets.

[0194] 1.3 Composition of the Material Produced

TABLE-US-00002 Isocyanate Amount of Iso Diol Amount of CE Total amount (Iso) [g] (CE) [g] [g] Iso 1 441.1 CE 2 158.9 600

[0195] 2. Production of the Membranes

[0196] 2.1 Abbreviations and Compounds:

[0197] NMP N-methylpyrrolidone

[0198] GLY glycerol

[0199] LEP liquid entry pressure

[0200] WVP water vapor permeability

[0201] 2.2 Test Methods

[0202] The liquid entry pressure of the membranes was determined in accordance with DIN EN 20811 using a pressure cell having a diameter of 60 mm with ultrapure water (salt-free water, filtered through a Millipore UF system) up to 4.0 bar (40 000 mm water column). The liquid entry pressure LEP is defined as the pressure at which the liquid water starts to permeate through the membrane. A high LEP allows the membrane to withstand a high water column (liquid).

[0203] The water vapor permeability (WVP) was determined using a cup method at 38 C. and 90% relative humidity in accordance with DIN 53122. High WVP values were desirable and permitted high water vapor flow rates. Tensile tests for modulus of elasticity and elongation at break were performed in accordance with DIN 53455/ISO 527.

[0204] Tensile properties were characterized in accordance with ISO 527-3.

[0205] 2.3 Production of Porous Membrane with N-Methylpyrrolidone as Polymer Solvent

[0206] In a three-neck flask equipped with a magnetic stirrer, 81 ml of N-methylpyrrolidone 1, 10 g of glycerol as second additive and 19 g of TPU polymer as per 1. were mixed together. The mixture was heated to 60 C. with gentle stirring until the homogeneous, clear, viscous solution thereof was present, which was degassed at room temperature overnight. Clear and transparent polymer solutions were obtained.

[0207] The polymer solution was subsequently heated again to 60 C. for 2 h and then spread at 60 C. onto a glass plate with a casting knife (150 microns), using an Erichsen coating machine at a speed of 5 mm/min. The membrane film was left to stand for 30 seconds, subsequently followed by immersion in a water bath at 25 C. for 10 minutes. After detaching the membrane from the glass plate, the membrane was transferred to a water bath for 12 hours. After multiple wash steps with water, the membrane was stored under humid conditions until characterization with respect to LEP and WVP. Table 1 summarizes the membrane properties.

TABLE-US-00003 TABLE 1 Compositions and properties of the membranes produced; thickness in [m], LEP in [bar], WVP in [g/m.sup.2*d], modulus of elasticity [MPa], elongation at break [%], Tg in [ C.]. TPU Tg Thickness LEP WVP Example 1 BUMDI 106 80 4 1220

[0208] 3. Welding

[0209] Two membranes as per section 1, example 1 were welded under air at 120 C. and a pressure of 3 bar for a period of time of three seconds, with a semiautomatic pulse welding machine (film welder) of the HPL 630 A type from Hawo Gertebau GmbH, D-74847 Obrigheim being used and a welded membrane composite with a weld seam having a width of 3.5 mm being obtained. The welded membrane composite had a thickness of 120 m in the area of the weld seam and was characterized in this area with respect to LEP and WVP. Table 3 shows the results of the characterization in comparison for the membrane of example 1 from section 2 and the welded membrane composite.

TABLE-US-00004 TABLE 3 Composition and properties of the membrane as per example 1 and of the welded composite; thickness in [m], LEP in [bar], WVP in [g/m.sup.2*d], Tg in [ C.]. TPU Tg Thickness LEP WVP Example 1 BUMDI 106 80 4 1220 Welded membrane BUMDI 106 120 4 1220 composite

[0210] The welded membrane composite exhibited the same good water vapor permeability and the same high liquid entry pressure as the unwelded membrane as per example 1. When determining the tensile properties, the seam of the welded membrane composite had a breaking stress of 1.5 MPa with an elongation at break of 8%.

[0211] The welded membrane composite was also examined by means of scanning electron microscopy (SEM). FIG. 1 is an SEM image of the cross-sectional area of the membrane composite in the area of the weld seam.