EP4695010A1

EP4695010A1 - Method of manufacturing a breathable, waterproof membrane

Info

Publication number: EP4695010A1
Application number: EP24715833.0A
Authority: EP
Inventors: Anna BELTZUNG; Mario STUCKI; Nina SPÖRRI
Original assignee: Dimpora Ag
Current assignee: Dimpora Ag
Priority date: 2023-04-14
Filing date: 2024-04-09
Publication date: 2026-02-18
Also published as: TW202506392A; CN120957804A; WO2024213539A1

Abstract

A method of manufacturing a breathable, waterproof membrane comprises the steps of a) providing a material web comprising at least one stabilizing layer and a membrane material holding templates and combined with the at least one stabilizing layer, b) bringing the material web into a washing machine, and c) washing the templates out the membrane, thereby bringing a porous structure into the membrane material. The method is industrially applicable for manufacturing a breathable, waterproof membrane with a minimum of crease marks and weak spots.

Description

TITLE

METHOD OF MANUFACTURING A BREATHABLE, WATERPROOF MEMBRANE

TECHNICAL FIELD

The present invention relates to a method of manufacturing a breathable, waterproof membrane and a membrane produced according to this method. The membrane may be associated with a fabric.

PRIOR ART

Breathable, waterproof membranes are well known. They prevent water to penetrate and allow moisture to pass through. A main field of use are clothes or garments and shoes. However, they are used in other fields as well.

Such membranes are often produced by stretching or phase inversion. However, these processes and membranes use forever chemicals, such as PFC (fluorinated compound), or toxic solvents, such as DMF (Dimethylformamide).

An improved method uses a template removal technique, called template removal method as well. Particles are mixed with a melted polymer. This mixture is extruded as a film and then, the particles are removed to create pores. The particles are usually removed by dissolving or dispersing. The particles act as templates. Usually, they are immiscible polymers or fillers, such as calcium carbonate.

This works well for small membrane sheets. However, industrial applicability requires an efficient way of particle removal. Since the membranes are quite thin, the risk to create crease marks and weak spots during this removal procedure is quite high.

EP 3 178 873 A1 discloses a method for manufacturing waterproof and breathable porous polymer membranes by coating a substrate with a dispersion comprising polymer, coated particles and diluent/solvent. The particles are removed by dissolution. These steps are adapted to a Roll-to-Roll process. When using Roll-to-Roll coating, polymer membranes with 100 m² can be prepared in a single piece.

EP 3 936 658 A1 describes a seamless manufacturing process for 3-dimensional waterproof and breathable porous polymer membranes by spraying, dip-coating or painting a substrate with a dispersion comprising polymer, coated or non-coated particles and diluent. The particles are removed by dissolution. The membrane is thereby treated piece by piece. Porosity is therefore created after the 3D coating and shaping. After complete removal of the template, the 3D object is washed again and then dried by room temperature or using a drying/ heating device.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method of manufacturing a breathable, waterproof membrane, which can be used industrially.

In one aspect of the invention a method of manufacturing a breathable, waterproof membrane, the method comprising the steps of

- providing a material web comprising at least one stabilizing layer and a membrane material holding templates and combined with the at least one stabilizing layer,

- bringing, preferably forwarding, the material web into a washing machine, and

- washing the templates out the membrane, thereby bringing a porous structure into the membrane material.

The material provided in the first step extends in an elongated shape thus forming a material web. The membrane material holding the templates is stabilized by the stabilizing layer.

The membrane material holding the templates is combined with the stabilizing layer. Preferably, it is connected to the stabilizing layer.

Preferably, the membrane material holding the templates is prepared by mixing melted membrane material with the templates. The material web is prepared by combining the membrane material with the stabilizing layer, thereby providing some kind of connections. The connection can be spread over the whole area (such as co-extruded with the filled membrane) of the material web or it can be punctually distributed over the whole area of the material web (such as dot-laminated after the film extrusion of the filled membrane).

In some variants of the method, the material web as a whole is given into the washing machine and the material web as a whole is washed at the same time. In some variants, the material web in the shape of a loose sheet is given in the machine. In other variants, the material web is provided as a roll and the entire roll is washed at the same time.

In preferred variants of the method, the material web is conveyed through the washing machine, thereby washing the templates out the membrane in the washing machine and bringing a porous structure into the membrane material. Preferably, the material web is provided in the shape of a roll and this roll is unwound when the material web is fed into the washing machine. The material web is therefore not all washed at the same time. Preferably the material web being unrolled for washing is wound to a second roll after washing i.e. , the material web is treated in a roll-to-roll washing.

In some preferred variants of the method, the material web is rolled into the shape of a roll and the rolled material web is brought or forwarded into the washing machine. The roll is also called bolt or bale. This roll washing method is capable of washing the templates out of the membrane even in the rolled up state, for example when the stabilizing layer or another layer acts as spacer between the membrane layers within the roll, thus giving access to the removal media to wash out the template, while the material web is still in a shape of a roll.

This method enables using the environmental friendly template removal technique for the production of long and wide membrane sheets. The delicate and fragile membrane material is supported and protected by a stabilizing layer, so that it is not damaged during the washing process. Nevertheless, the washing process can be performed quite efficiently, since the membrane material in the shape of a material web can be washed, preferably by conveying the web through the washing machine or by giving the web into the washing machine in the shape of a roll.

In some variants of the inventive method, the material web is conveyed and/or washed in a continuous process, in other variants, the material web is conveyed and/or washed in a batch process. Preferably, it is conveyed successively, i.e. either in batches or continuously. The tension usually needed in the washing machine can be loaded on the stabilizing layer. The membrane material is therefore handled carefully. This minimizes damages to the membrane and increases the quality. For example, breaking, ripping and crease marks or folds or weak spots, which may lead to undesired holes in the membrane, are avoided or at least minimized. Furthermore, clean cut on the side of the membrane is enabled.

In preferred embodiments, the at least one stabilizing layer is also present in combination with the membrane material, when the material web is dried after the washing. This is advantageous since the tension usually needed in the drying process can also be loaded on stabilizing layer.

In some methods, the washing out of the templates is done without any stabilizing layer and the at least one stabilizing layer is used afterwards in the drying step. The combination of the stabilizing layer and the membrane material can be made by fixation, such as lamination, or by rolling up or by other means, as mentioned in this text. This is a separate invention, which is also claimed in the patent application.

In some preferred variants of the method, the washing machine comprises an aqueous bath, through which the material web is conveyed. The liquid is preferably water, acid, or a mixture of water and acid. Preferred are acetic acid, formic acid or citric acid and most preferred is water and/or sulfamic acid. The medium used for washing can also be a basic environment or water mixed with solvents, such as ethanol, isopropanol.

Preferably, the membrane is a polymer membrane and the templates are minerals or salts. Other materials and templates known in the state of the art can be used as well.

The combination of the stabilizing layer and the membrane material can be washed immediately after having been combined, for example after exit of a co-extrusion device. The combination of the stabilizing layer and the membrane material can also be rolled up into a roll.

Typical sizes of the material web rolled up are 150 to 160 cm width and several hundred meters length, preferably 800 to 1000 m. Other sizes can be realized as well. The membrane material, i.e. the membrane film, is very thin. A typical thickness is between 25 to 60 pm or 30 to 50 pm prior to washing and 15 to 35 pm after washing, more preferably 30 to 35 pm prior to washing and 15 to 25 pm after washing. Preferably, the washing machine is a known machine, which can handle material web material. Preferably, the washing machine can unroll and re-roll the material web material or it is a washing machine which can treat rolled material. When the washing machine is unrolling and rerolling, the material web is preferably washed in between these two processes. Preferably, the combined material is washed in a tensioned state, at least when washed in the unrolled state. When it is washed in a rolled state, the stabilizing layer forming a middle layer, i.e. a spacer, takes the tension from the membrane and provides support during washing and drying.

Preferably, the washing machine is a dyeing machine, i.e. a machine which is mainly developed and used to dye materials.

Preferably, the washing machine is a jigger dyeing machine or a JET overflow machine, a Haspelkufe (also called winch-reel machine) or an open width washing machine or a beam dyeing machine, wherein the machines named are suitable for washing instead of/or in addition to dyeing. Other types of machines can be used as well. The washing machines are industrially applicable machines being able to process large material web, preferably of several hundred meters.

In the Haspelkufe machine, the material web is continuously moved over a wrinch and immersed in a basin below, the basin being filled with a liquid. The material web is guided through the machine without tension, so that the material web is not distorted.

In a Jet overflow machine, the material web is moved in the same way as in the Haspelkufe machine, wherein the liquid is moved as well. In addition, the material web is usually moved faster than in the Haspelkufe machine.

Haspelkufe (winch-reel machine) and Jet overflow machine have the advantage that the costs for washing the material web can be minimized. The machines are less expensive than the other machines mentioned above. In addition, the washing process is faster and therefore more cost-efficient than the washing process in the other machines mentioned above. They also do need less water than the open width washing machine, which decreases the costs as well.

In the Haspelkufe machine and the Jet overflow machine the material web is a little bit scrunched or crumpled up.

In an open width washing machine, the material web is kept under tension, thus avoiding creation of wrinkles and the full width stays unchanged throughout the process. The material web is conveyed through a roll-to-roll process, entering the different baths at a speed which allows the right residence time, using several rolls located in and outside the bath, to ensure complete dissolution of the template and subsequent rinsing. A drying and a re-rolling step are put at the end, in the same continuous production. The final product is the material web in a form of a roll, including the membrane material in a porous state.

The open width machine applies some tension of the material web and maintains it width. However, it needs quite a lot of water.

A jigger dyeing machine comprises a large, closed vat with at two main rollers located in the top half of the machine. The material web is wound onto one roller and the fed onto the other roller. A liquid is located at the bottom of the vat below the two rollers. Usually, a number of smaller rollers are located in the liquid, the smaller roller acting as guide rollers. The liquid intended to be used with such a machine is a dyeing liquid. However, in the invention claim the liquid is a washing liquid, for example water, and the machine is used for washing, not for dyeing. This machines only needs a minimum of liquid.

The use of Haspelkufe (winch-reel) machines and jet overflow machines is mostly preferred. These machines are especially suitable for washing fabrics or for washing material webs with membranes with no co-extruded stabilizing layer. In addition, these machines are especially suitable for washing material webs with layers laminated to the membrane, such as fabrics.

All machines mentioned above can be used for laminated membranes. However, Jigger dyeing machines and Open width machines are preferably used when the material web comprises a co-extruded stabilizing layer.

Especially material web with co-extruded stabilization layers which are washed together with the membrane and material webs having a co-extruded polymer stabilizing layer and no layers laminated to the membrane are preferably washed with open width washing machines or with jigger dyeing machines, wherein the open width machine is most preferred because of the repeated short residence time in the acid, at high speed, which minimizes the costs.

The following table shows which machine is preferred for which material web:

*Shore D of the raw polymer to make the membrane material out of. **Elongation at break of the washed membrane material.

Especially, when using a co-extruded stabilizing layer, the following preferably applies:

For choosing one machine over the other, the elongation at break of the Membrane material filled with template is compared with the elongation at break of the stabilizing layer. Preferably, the first one should be higher. This way, the tension can stay in the stabilizing layer without damaging the membrane material.

The membrane material holding the templates is combined with at least one stabilizing layer. Different ways to combine the materials are possible. In some preferred variants of the method, the membrane material is fixed to the at least one stabilizing layer. For example, the layer can be laminated to the membrane material, for example with dotted point of glue or the layer can be co-extruded together with the membrane material holding the templates. In other variants of the method, the membrane material and the at least one stabilizing layer are rolled together, wherein the stabilizing material forms a middle layer between the windings of the rolled up membrane material. This stabilizes the membrane material as well. This middle layer method is especially advantageous, when a beam dyeing machine is used for washing the templates out of the membrane material. Other ways to stabilize the membrane material by using a stabilizing material can be used as well Preferably, there is a first stabilizing layer of the at least one stabilizing layer, which is coextruded together with the membrane material holding the templates. This is a quite efficient way to attach the membrane to the stabilizing layer, minimizes the stress to the membrane, and therefore minimizes the risk that the membrane is damaged. The materials for the first stabilizing layer are preferably chosen by opposite polarity of the material used for the membrane holding the templates to facilitate separation when required. Typical materials used in the first stabilizing layer are polyethylene (PE, LDPE), polyamides (PA), polypropylene (PP), polymethylmetactrylate (PMMA), polyester (PES for example including PLA, PET, PCL, PBAT, PHB, PHA), polyurethane (TPU, polyester- or polyether-based), preferably having a thickness of 10 - 50 microns.

In some variants of the method, the membrane and the at least one stabilizing layer have approximately the same width.

In some variants of the method, the membrane holding the templates is extruded without the first stabilizing layer and is then hot-calendered to a knitted, woven or non-woven fabrics without point of glues to provide stability during washing.

In some variants of the method, the membrane holding the templates is separated from the first stabilizing layer and re-attached by means of side-sewing or removable glue on each side, or other side-attaching methods, to a knitted, woven, non-woven fabrics or washstable paper without point of glues to provide stability during washing.

In some variants of the method, the supported membrane holding the templates entering the washing step can be clamped or attached on both sides to provide more tension and stability during washing and drying. This is preferably the case when using an open-width washing machine.

In some variants of the method, the at least one of the at least one stabilizing layer, preferably the first stabilizing layer, has a first width and the membrane material holding the templates has a second width, wherein the second width is smaller than the first width. In other variants, the stabilizing layers have the same width as the membrane material. This is especially the case when the stabilizing layer and the membrane material is co-extruded.

When the stabilizing layer has a larger width than the membrane material, the internal conveying means of the washing machine and/or external conveying means are enabled to convey the material web mainly by contacting these membrane-free regions of the stabilizing layer. This applies for the washing step and preferably for the drying step as well. This further minimizes the risk of damaging the membrane. Preferably, the at least one of the at least one stabilizing layer, preferably the first stabilizing layer, forms two borders along the elongate edges of the membrane material holding the templates. This facilitates the transport of the membrane to the washing machine, through the washing machine and out of the washing machine additionally.

In some preferred variants of the method, the above mentioned first stabilizing layer is conveyed together with the membrane material holding the templates through the washing machine, wherein the membrane is fixed to the first stabilizing layer. Therefore, no additional fixing steps have to be accomplished. However, fixing with clambs or machinery fixing still can be used as additional fixing steps as well.

Preferably, the first stabilizing layer is separated and preferably removed from the membrane material after the templates have been removed. This means that the first stabilizing layer is removed from the membrane material after the washing step, preferably after a drying step.

In some variants of the method, a second stabilizing layer of the at least one stabilizing layer is connected to the membrane material holding the templates, wherein the second stabilizing layer is arranged on the opposite to the first stabilizing layer, with the membrane material forming a middle layer. This first stabilizing layer is preferably co-extruded with the membrane material holding the templates. However, this first stabilizing layer can also be fixed to the membrane material by other ways or means of fixation. The connection of the second stabilizing layer to the membrane material is preferably made by lamination with dotted points of glue. The fixation can also be made with alternative means or ways.

In some variants of the method, at least the second stabilizing layer forms two borders along the elongate edges of the membrane material holding the templates and has therefore not the same width as the membrane material. In some embodiment, the first stabilizing layer does also form such borders on both elongate sides of the membrane material. In other embodiments, especially when the first stabilizing layer is co-extruded with the membrane material, it does not form borders but the materials have approximately the same width.

Preferably, the first stabilizing layer is removed before the second stabilizing layer and the membrane material holding the templates are brought into, preferably forwarded through, the washing machine. This means the first layer mainly helps to attach the second stabilizing layer to the membrane and the newly combined material web is brought into, preferably forwarded through, the washing machine. The newly combined material web can for example be conveyed through the washing machine or it can be given into the machine and washed in the machine as a roll, for example, when a beam-dyeing machine is used.

Is some variants of the method, the first stabilizing layer is removed after the second stabilizing layer is fixed to the membrane material. In other variants, the first stabilizing layer is removed prior that the second stabilizing layer is fixed to or combined with the membrane material.

Preferably, this second stabilizing layer remains on the membrane material after the templates have been removed. Preferably, the second stabilizing layer and the membrane material form a final laminate. Preferably, the second stabilizing layer is made of a fabric. The fabric can be non-woven, woven, knitted, crocheted or felt.

Preferably, the washing process uses temperatures of 15 - 80 °C. When acid is used, the acid concentration is preferably 10 - 80%. Washing speed, i.e. the time of the section of the material web being in the washing machine is preferably 20 - 200 min, which gives a speed of 1 -20 m/min.

Preferably, the drying process uses temperatures of 50 -100 °C. Drying speed is preferably 1 -30 m/min.

Preferably, no pressure is applied during the washing process and/or no pressure is applied to during the drying process. When drying, preferably a clamping frame is used to fix the membrane web.

The methods mentioned above can therefore be understood as methods for removing templates of a membrane as well. In this method for removing templates, the step of removing a first layer of the at least one layer before or after bringing the material web into the washing machine is preferred.

In one aspect of the invention, a breathable, waterproof membrane is manufactured according to the methods mentioned above. Further variants and embodiments of the invention are laid down in the dependent claims.

Unless otherwise stated, the following definitions shall apply for this text:

Width of material, also called Width of cloth, Web-shaped material or Material web’, is a long or continuous sheet having a length, which is a multiple times longer than its width. It can be rolled up or it can be folded a multiple of times. It can have one layer or a multiple of layers combined with each other or connected to each other, especially fixed to each other or rolled up together so that one layer forms a middle layer between windings of the other layer. The expression web defines the outer shape of the material. The expression web is not restricted to a special way of manufacturing the material itself.

Polymer, is known in the technical field. The term refers to a material of repeating structural units ("monomers"), particularly to synthetic polymers (comprising synthetic monomers). The term thus includes homo-polymers, co-polymers and blends thereof. Polymers may be cross-linked.

Membrane’, is a thin sheet or layer.

Template: is known in the technical field and includes crystalline or amorphous materials. The term includes uncoated particles and coated particles as well as treated particles and untreated particles. Templates are also called fillers or particles in the technical field. Templates according to this text are small. Preferably, they have a diameter in the submicron size range, whereby particle sizes are preferably between 5 to 15'000 nm, such as 2000 to 8'000 nm. Suitable particles may be obtained from a range of preparation methods, including high temperature-gas phase processes (such as flame synthesis, laser processes and plasma processes), and liquid phase chemical methods (such as precipitation and sol-gel processes), and milling of particles. Particles particularly suitable in the context of the present invention may be obtained by a precipitation process or by milling of naturally occurring materials.

Holding templates: means that the templates are located within a material, partially or fully enclosed by the material.

Stabilizing layer, a layer, which can support and stabilize another layer. Co-extruded: is produced by simultaneous extrusion of two or more layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

Figure 1 shows a schematic perspective presentation of a first arrangement to perform the method according to the invention;

Figure 2 shows a schematic perspective presentation of a second arrangement to perform the method according to the invention and

Figure 3 shows a schematic perspective presentation of a third arrangement to perform the method according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a first way to perform the inventive method. The device used to perform the method is shown schematically.

A material web comprising a membrane material 1 holding templates 2 is coextruded with a first stabilizing layer 3. The membrane material 1 is preferably a polymer. The templates 2 are also called in the technical field fillers, particles or template particles. They are preferably salts or minerals. The templates 2 have preferably mixed into the membrane material 1 , when the membrane material 1 was in a melted state.

Typical sizes of the material web are 150 to 160 cm width and several hundred meters length, preferably 800 to 1000 m per roll. Other sizes can be realized as well.

The membrane material, i.e. the membrane film, is very thin. A typical thickness is between 25 to 60 pm and preferably between 30 to 50 pm in the unwashed state. The first stabilizing layer 3 is preferably made of one of a polyolefin, a polyamide, a polyester, a polymethylmetacrylate or of combinations thereof. The thickness of the first stabilizing layer 3 is preferably between 10 to 50 pm.

The width of the first stabilizing layer 3 may be larger than the width of the membrane material 1. In some variants, they have the same size. However, for better understanding, the figures show different widths for the stabilizing layers and the membrane material. The first stabilizing layer 3 preferably forms a border 30 on each side of the membrane material 1 , the borders 30 extending along the whole length of the material web.

The material web is preferably provided in the shape of a roll, wherein the material web is preferably wound onto a support roll 6. This enables handling, transport and storage of the co-extruded product.

The material web is unrolled and fed into a washing machine 50. The washing machine is a machine known in the textile industry, such as an open-width washing machine. In other variants, machines which are usually used for dyeing but which can also be used for washing, are used. The machine preferably comprises a bath or other means to wash the unrolled part of the material web or the rolled up material web.

In the washing machine 50, the material web comprising, or preferably consisting of the first stabilizing layer 3 and the membrane material 1 holding the templates 2, is washed in one single step or in several steps. It is preferably washed with acid and/or water. The acid is preferably one of formic acid, acetic acid, hydrochloric acid, citric acid, sulfamic acid.

Caused by this washing process, the templates 3 are removed from membrane material 1 , thereby creating pores 7 in the membrane material 1.

The washing machine 50 includes a dryer or a drying machine 51 following the washing machine 50. In other variants, the drying step is not a continuous step within the same system, but it is conducted afterwards in another system or environment.

The thickness of the membrane material after washing is preferably between 15 to 25 pm.

After washing and preferably after drying, the washed material web is conveyed to a first combining station 8, where a second stabilizing layer 4 is connected with the material web.

The second stabilizing layer 4 is arranged on the opposite side to the first stabilizing layer 3. Preferably, the second stabilizing layer 4 is a substrate or fabric, such as non-woven, woven and knits based on polyester, polyamide, cotton, polypropylene, polyethylene, elastane, cellulose cotton, polyester, or polyamide, or of combinations thereof. More preferably, it is a fabric with a weight between 10 - 300 g/m2. More precisely, the second stabilizing layer 4 can be either a so-called backer fabric typically lightweight (10 - 60 g/m2) or a so-called face fabric, typically heavier (60 - 300 g/m2 and more preferred 80 - 200 g/m2). The third layer with the same characteristics as the second stabilizing layer can also be added via dot-lamination prior to washing, thus washing a fully constructed 3L. All the fabrics mentioned preferably have an elongation at stretch between 50-200 % on both sides measured via ASTM D882-12 (ISO 527-3) or ISO 13934 for defect-free washing results.

The weight of the second stabilizing layer 4 is preferably 10 to 300 g/m² , which may depend if the second stabilizing layer 4 is a backer, which is lighter, or a face fabric, which is thicker.

The stabilizing layer 4 is fixed to the membrane material 1. The stabilizing layer 4 is preferably laminated to the membrane material 1. Preferably, it is laminated with dotted points of glue. The combining station 8 may comprise calendaring means. Other techniques known in the state of the art to connect the second stabilizing layer with the membrane material can be used as well.

Preferably, the second stabilizing layer 4 is broader than the membrane material 1 and forms borders 40 on both sides. Preferably, the first stabilizing layer has the width as the membrane material 1.

In a next step, the first stabilizing layer 3 may be separated and removed from the membrane material 1. The removing station 9 may be a roll-to-roll/derolling manufacturing system with tension.

The material web, now consisting of the washed and porous membrane material 1 and the second stabilizing layer 4 attached to the membrane material 1 is preferably conveyed to a second combining station 10. A third layer 11 is attached to the membrane material 1 and/or to the second stabilizing layer 4, wherein the third layer 11 is attached on the opposite side to the second stabilizing layer 4. In other embodiments, no third stabilizing layer 11 is added.

Preferably, the third stabilizing layer 11 is laminated to the membrane material 1. Preferably, it is laminated like the second stabilizing layer 4.

The third stabilizing layer 11 is a is substrate or fabric, such as non-woven, woven and knits based on polyester, polyamide, cotton, polypropylene, polyethylene, elastane, cellulose cotton, polyester, or polyamide, or of combinations thereof. More preferably, it is a knit or woven.

The weight of the third layer is preferably 10 to 300 g/m²

In this embodiment, the three layers, i.e. the washed membrane material, the second stabilizing layer 4 and the third stabilizing layer 11 are part of a final fabric, i.e. they are part of a final product.

Figure 2 shows a second way to perform the inventive method. The device used to perform the method is shown schematically. Some method steps, devices and materials used are identical with the steps, devices and materials described with regard to figure 1 . They are not repeated anymore.

The difference to the method and device according to figure 1 is that the second stabilizing layer 4 is connected with the material web before the material web is washed. The other difference is that the first stabilizing layer 1 is removed from the material web comprising the already fixed second stabilizing layer 4 before the material web is washed. After the washing procedure and, preferably after a drying process, the third stabilizing layer 11 is fixed to the other side of the washed and now porous membrane material 1.

The method according to figure 2 can be used with any washing machines. However, it is especially suitable for JET, Haspelkufe or an open-width washing machine. When using a beam-dyeing machine, the material web is rolled up after removal of the first stabilizing layer and the roll is brought into the washing machine. Other kind of layers can be added as well. Not all layers have to be stabilizing layers.

Depending on the variants of the method, the material web, which always comprises the membrane material, is preferably laminated with 2L (one fabric on one side), 2.5L (one fabric on one side and a print on the other side) or 3L (one fabric on each side of the membrane). As mentioned above, it can also be a co-extruded layer.

During washing, these laminates can be present on the material web in addition or instead of a co-extruded first stabilizing layer.

When the material web is washed as a roll and/or when the membrane material is connected with a fabric during the washing procedure, it is preferably pressed with a calendaring step afterwards in order to expedite the following drying process.

During the drying process, a tension is preferably applied on both sides of the material web. The tension is preferably applied by the stabilizing layer and/or by mechanical means, such as clamps.

With regard to the method shown in figure 1 , the first stabilizing layer 1 can also be removed after drying but prior to attaching the second stabilizing layer. In some cases, it may also be removed before drying.

With regard to the method shown in figure 2, the material web comprising the washed membrane material and the second stabilizing layer can also be rerolled in this state and it can be unrolled later on to apply the third layer and even more layers.

Figure 3 shows a third way to perform the inventive method. The device used to perform the method is shown schematically. Some method steps, devices and materials used are identical with the steps, devices and materials described with regard to figures 1 and 2. They are not repeated anymore.

In this variant of the inventive method, the membrane material 1 is first fixed to the first stabilizing layer 3. Preferably, it is co-extruded. At the first combining station 8, the second stabilizing layer 4 is arranged on a side of the membrane material 1 being opposite the side of the first stabilizing layer 3. In the variants according to figures 1 and 2, the second stabilizing layer 4 is preferably laminated to the membrane material 1 or otherwise fixed to the membrane material 1. In this variant, can also be fixed to it. However, it is preferably just arranged on this side of the membrane material 1 without any kind of connection.

In the removing station 9, the first stabilizing layer 3 is removed from the membrane material 1. The combination of membrane material 1 and second stabilizing material 4 is then rolled up, so that the second stabilizing material 4 forms a middle layer between the windings of the membrane material 1. This roll is then entered as a roll into the washing machine 50. This washing machine is preferably a beam dyeing machine. After washing out the templates 2, the roll is dried in the drying machine 51 , which can be part of the beam dyeing machine 50 or which can be a separate machine. In other variants, the roll is unrolled before drying and the unrolled material web is dried.

After drying, the dried membrane material 1 comprising pores 7 is separated from the second stabilizing layer 4 in a second removing station 12.

The second stabilizing layer 4 has preferably an open knit structure, which means it is porous or has holes, so that the templates 7 can be washed out of the roll. The material is the second stabilizing layer 4 is preferably a thick fabric such as a non-woven material or a spacer, "thick" means preferably 500 - 20’000 micron.

The methods described are industrially applicable for manufacturing a breathable, waterproof membrane with a minimum of crease marks and weak spots.

LIST OF REFERENCE SIGNS

1 membrane material 6 support roll

2 templates 7 pores

3 first stabilizing layer 8 first combining station

30 border 9 removing station

4 second stabilizing layer 10 second combining station

40 border 11 third stabilizing layer

50 washing machine 12 second removing station

51 drying machine

Claims

1. Method of manufacturing a breathable, waterproof membrane, the method comprising the steps of

- bringing the material web into a washing machine, and

- washing the templates out of the membrane, thereby bringing a porous structure into the membrane material.

2. Method according to claim 1 wherein the at least one stabilizing layer is fixed to the membrane material.

3. Method according to any one of claims 1 or 2 wherein the material web is conveyed through the washing machine, thereby washing the templates out the membrane in the washing machine and bringing a porous structure into the membrane material.

4. Method according to claim 1 wherein the material web is rolled into the shape of a roll and the rolled material web is brought into the washing machine.

5. Method according to any one of claims 1 to 4 wherein the washed material web combined with the at least one stabilizing layer is washed in a dyeing machine.

6. Method according to any one of claims 1 to 5 wherein the membrane is a polymer membrane and the templates are minerals or salts.

7. Method according to any one of claims 1 to 6 wherein the washing machine is a jigger dyeing machine or a JET overflow machine, a Haspelkufe or an open -width washing machine or a beam dyeing machine.

8. Method according to any one of claims 1 to 7 wherein a first stabilizing layer of the at least one stabilizing layer is co-extruded together with the membrane material holding the templates.

9. Method according to claim 8 wherein the first stabilizing layer is brought together with the membrane material holding the templates into the washing machine.

10. Method according to one of claims 8 or 9 wherein the first stabilizing layer is separated from the membrane material after the templates have been removed.

11 . Method according to any one of claims 8 or 9 wherein a second stabilizing layer of the at least one stabilizing layer is connected to the membrane material holding the templates, wherein the second stabilizing layer is arranged on the opposite to the first stabilizing layer.

12. Method according to claim 11 wherein the first stabilizing layer is removed before the second stabilizing layer and the membrane material holding the templates are brought into the washing machine.

13. Method according to claim 11 or 12 wherein the second stabilizing layer remains on the membrane material after the templates have been removed and the second stabilizing layer forms a part of a final fabric.

14. Method of manufacturing a breathable, waterproof membrane, the method comprising the steps of

- providing a wet material web comprising at least one stabilizing layer and a membrane material comprising pores which have been generated by washing off templates, the membrane material being combined with the at least one stabilizing layer,

- bringing the material web into a drying machine, and

- drying the material web.

15. Breathable, waterproof membrane manufactured according to the method of any one of claims 1 to 14.