Method of making fabric having hydrophobic and oleophobic properties

Abstract

The invention relates to a method for producing a fabric having hydrophobic and oleophobic properties, said fabric having a halogen-free plasma coating, whereby the method comprises: a step DHF of depositing a plasma coating on the fabric by plasma-enhanced chemical vapor deposition (PECVD) by means of plasma polymerization of halogen-free precursor monomers, wherein the halogen-free precursor monomer is an organosilane, siloxane and / or hydrocarbon precursor wherein the plasma enhanced chemical vapor deposition is carried out under a protective atmosphere as a low pressure plasma process wherein the fabric comprises a woven monofilament fabric of polymeric material having a filament diameter of 10 [mu] m to 150 [mu] m and meshes of between 5 [mu] m and 200 [mu] m.

Description

[0001] The present invention relates to a method for producing a fabric having hydrophobic and oleophobic properties, said fabric having a halogen-free plasma coating according to standards IEC 62321-3-2:2020, EN 14582:2016 and / or ASTM D7359:2018, in particular free of per- and polyfluorinated substances (PFAS). According to the invention, these properties can be evaluated according to DIN 55660-2:2011-12 for the contact angles of water, diiodomethane and hexadecane and according to DIN EN ISO 14419:2010 for the oil repellency class.

[0002] Furthermore, the present invention relates to a fabric having hydrophobic and oleophobic properties, comprising a halogen-free plasma coating formed thereon according to standards IEC 62321-3-2:2020, EN 14582:2016 and / or ASTM D7359:2018, in particular free of per- and polyfluorinated substances (PFAS).

[0003] Man-made organic compounds such as per- and polyfluoroalkyl substances are substances of very high concern (SVHCs) and represent a large class of compounds that have been used in various industries. The use of these compounds as processing additives and as surfactants has been reported in the literature since the 1940s. These compounds - which have special properties including fire resistance and oil, stain, grease and water repellency - have been commonly used in the production of non-stick cookware, specialized clothing and textiles, stain repellents, metal coatings and fire-fighting foams. They are divided into two groups of PFAS: perfluoroalkyl sulfonic acids (PFSAs) and perfluorocarboxylic acids (PFCAs). These are synthetic substances that do not occur naturally in the environment, and PFAS, including their related salts, have been detected in different types of aqueous environments at varying concentrations. This is not surprising, as some PFAS are persistent and bioaccumulate.

[0004] PFAS are increasingly being detected as environmental pollutants, and some are associated with adverse effects on human health. Furthermore, due to the strength of the C-F bond, once present, they are very resistant to degradation. Furthermore, it has been documented that most PFAS are also easily transported in the environment, covering long distances away from their sources of release. C8-based PFAS are already listed as controlled substances in the EU, and perfluorooctane sulfonic acid (PFOS) was classified as a persistent organic pollutant (POP) in 2009.

[0005] Since 2015, some countries have even banned the formulation of products containing PFOS and large amounts of PFOA. Even the use of C6 fluorocarbons (FCs) has led to global environmental pollution, as they contain large amounts of PFAS and trace amounts of perfluorooctanoic acid (PFOA) and its salts. Consequently, these substances have raised concerns due to their persistence and potential for bioaccumulation. Consequently, the REACH Regulation (EU / 784 / 2020), which came into effect on December 3, 2020, has set a PFOA threshold of less than 25 ppb (parts per billion).

[0006] This has already begun a shift from longer chain FCs (C8, C6) to ultra-short chain C3 to C1 fluorocarbons such as per- and polyfluoroalkyl substances (PFAS). While these compounds, in principle, offer hydrophobic and oleophobic properties, it is recognized that these short-chain monomers and polymers still contain a significant amount of fluorine in order to achieve comparable hydrophobic and oleophobic properties compared to long-chain FCs. Although the effects of long-term exposure to PFAS-containing substances on humans and the environment are not fully understood, coatings based on short chains still present health hazards.

[0007] Unless necessary measures are taken to limit these very persistent compounds, humans, plants and animals are likely to be increasingly exposed. It is estimated that if no action is taken, approximately 4.4 million tonnes of PFAS will end up in the environment over the next 30 years.

[0008] A new regulatory process has therefore been initiated and a corresponding draft regulation has been prepared by the relevant authorities and submitted to ECHA in January 2023. It aims to reduce emissions of PFAS into the environment and make products and processes safer for humans. This revolutionary proposal will not focus on just one chemical, as has been the case until now, but will cover all PFAS classes. The main areas of application are, in particular, the TULAC sector (textiles, upholstery, leather, clothing and carpets), as specified in the regulatory proposal dossier (Annex XV to REACH). The proposal sets a limit of 25 ppb for any PFAS, a limit of 250 ppb for the sum of PFAS and a limit of 50 ppm for polymerized PFAS (calculated as total fluorine).

[0009] Although the restriction is making progress and may be implemented more quickly, the demand for hydrophobic and oleophobic coatings that do not contain PFAS is increasing dramatically. Silicon-based coatings, mainly containing silanes and siloxanes, are considered to be safer alternatives for use on fabrics. Chemically, silicones are composed of Si atoms bonded to organic hydrocarbon groups. They include organosilanes (trimethylsilane, etc.) and siloxanes (hexamethyldisiloxane, tetramethylsilane, etc.). It is reported that Si-based films deposited by plasma are of interest in semiconductor manufacturing and flexible solar cells.

[0010] EP 3 101 17 0A1 teaches a fluorine-free, durable plasma nanocoating on a textile substrate by low-pressure plasma polymerization. The coating should provide a sufficient level of water repellency (i.e., hydrophobicity) for certain textiles. Regarding durability, the coating applied to the textile fabric should withstand repeated washing and should be able to achieve a reasonable level of water repellency after a reasonable number of washing cycles.

[0011] WO 2022 / 171581 A1 discloses a hollow cathode plasma polymerization method, which is applied to textile substrates to obtain a durable halogen-free (especially fluorine-free) hydrophobic polymer coating.

[0012] However, for textiles, plasma polymerized silicones have been deposited to ensure dielectric properties, thermal stability, scratch resistance, and to adjust wettability (ie, hydrophobicity), but oleophobic properties have not been reported to date.

[0013] Siloxanes are widely used as precursor monomers for plasma processes to obtain fluorine-free plasma coatings. Plasma polymers from these precursors show promising mechanical properties, such as low internal stress, good adhesion, and excellent hydrophobic barrier properties. Although the water resistance provided by plasma coatings such as TMDSO is promising, they cannot provide any oleophobic properties as disclosed in EP 4 177 050 A1. Therefore, for the reasons of PFAS restrictions, a general trend is to obtain good hydrophobic and oleophobic coatings. In addition, there is still a need for next-generation super-hydrophobic and oleophobic coatings that are highly repellent to grease.

[0014] It is therefore an object of the present invention to provide a method for producing a fabric having hydrophobic and oleophobic properties, said fabric having a halogen-free plasma coating, in particular free of per- and polyfluorinated substances (PFAS), and to provide a fabric having hydrophobic and oleophobic properties, said fabric comprising a halogen-free plasma coating formed thereon, in particular free of per- and polyfluorinated substances (PFAS).

[0015] According to the invention, this object is achieved, on the one hand, by a method having the features of claim 1 and by a textile, such as a textile having the features of claim 14 .

[0016] Preferred embodiments of the invention are set out in the corresponding dependent claims.

[0017] According to the method of the present invention, in the DHF step, a plasma coating is deposited on the fabric by plasma polymerization of halogen-free precursor monomers using plasma-enhanced chemical vapor deposition (PECVD). The halogen-free precursor monomers are organosilane, siloxane, and / or hydrocarbon precursors. Furthermore, the PECVD is performed as a low-pressure plasma process under a protective atmosphere. The fabric comprises a woven monofilament fabric of a polymer material having a filament diameter of 10 to 150 μm and a mesh opening between 5 and 200 μm.

[0018] The basic idea of ​​the present invention is to determine the effect of fabric geometry on achieving a good oleophobic textile surface. The textile or fabric structure and construction depends on many factors, such as the weave type, fiber content type, fiber fineness, mesh size, i.e., the number of threads per centimeter. Compared to flat surfaces (films, polymer solids, etc.), fabrics have a complex architecture that actually consists of two surfaces, one of which is macroscopic and visible to the naked eye. It has been found that the degree of oleophobicity is closely related to the textile structure and weaving construction. Thus, in addition to the plasma process parameters and coating properties, capillary phenomena are also strongly affected by the mesh geometry, in particular the mesh (the space between two adjacent filaments) and the yarn (filament) diameter. The fabric can include regular openings in a square or rectangular configuration. Surprisingly, according to the present invention, it was found that a fabric composed of a woven monofilament fabric of a polymer material (having a filament diameter between 10 μm and 150 μm and a mesh between 5 μm and 200 μm) also provides oleophobic properties when it has only a plasma-deposited coating based on organosilane, siloxane and / or hydrocarbon precursors (which is believed to provide only hydrophobic properties).

[0019] Plasma treatment of organosilicon as in step DHF results in complex plasma phase chemistry and tunability of film composition. In fact, depending on the organic part (CH x ) in the membrane, when there are a large number of (CH x ), silane-like properties can be obtained, which exhibit hydrophobic properties, or SiO2-like inorganic coatings can be obtained in case an oxidant (e.g. oxygen) is added to the feed gas, which produces a hydrophilic surface.

[0020] Liquid precursors that can be used for the deposition of Si-based coatings are hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDSO), divinyltetramethyldisiloxane (DVTDSMO), tetramethylsilane (TMS). Such monomers have a high vapor pressure, are non-toxic and can be processed at low temperatures. Due to the -CH3 groups remaining within the Si-O network, they can be used to deposit hydrophobic coatings onto fabrics and fibers. Carbon-rich plasma-polymerized TMDSO (pp-TMDSO) obtained using a PECVD process from pure TMDSO shows promising mechanical properties such as low internal stress, good adhesion to the substrate.

[0021] On the other hand, the organic character of plasma-polymerized TMDSO can be obtained from a gas mixture of TMDSO / N2 / Ar (He) using a hollow cathode plasma polymerization. To explain the hollow cathode system, the plasma is generated in a narrow interelectrode gap, usually with a coaxial geometry, and it is blown out of this region by a gas flow, directly onto the substrate: the plasma treatment or deposition is thus carried out in a downstream mode as described in WO 2022 / 171581 A.

[0022] The two types of coatings developed in the DHF step show excellent hydrophobic properties and good oleophobic barrier properties on monofilament fabrics, while the mesh and mesh diameter play an important role in obtaining oleophobic properties.

[0023] In one embodiment, the method can comprise an additional step DLC of coating the fabric by a PVD method using an argon plasma sputtering a carbon target and / or by a PVD method using a hydrocarbon gas, wherein the step DLC is carried out before the step DHF. In the DLC step, an amorphous hydrogenated diamond-like carbon film is deposited on the fabric.

[0024] Amorphous hydrogenated diamond-like carbon films (also called a-C:H or DLC) have shown several properties such as high hardness, high wear resistance, chemical inertness, oxidation resistance, thermal stability, high degree of cross-linking and low friction coefficient. In addition to the coating properties, an important aspect is that DLC coatings can be deposited at low substrate temperatures, for example on temperature-sensitive polymer materials such as monofilament fabrics. DLC coatings, consisting of a highly cross-linked network of carbon and hydrogen atoms, generally have a high compressive stress. Such high stress values can lead to poor adhesion to the substrate and limit practical applications. Since DLC coatings have a high adhesion to the substrate, the coating can be used as an adhesion-promoting layer for the DHF coating.

[0025] According to the present invention, two different methods for depositing DLC ​​coatings are proposed. One method deposits the DLC film by PECVD using a radio frequency (RF) glow discharge of a hydrocarbon gas with a negative self-bias voltage applied to the substrate. The second type of DLC coating can also be deposited by PVD sputtering. The target used is composed of carbon or pure graphite, and the working gas during the sputtering process is argon.

[0026] The DHF step can be performed in the same reactor after the DLC step. This is particularly advantageous when using a PECVD method to produce amorphous hydrogenated diamond-like carbon films. Alternatively, the DHF step can be performed in a separate reactor with a time delay between these steps.

[0027] The method may further comprise an APL step of producing an adhesion promoting layer by plasma polymerization of a hydrocarbon gas and / or a mixture of a hydrocarbon gas, a reactive gas and an inert gas, wherein the APL step is performed before the DLC step, or if no DLC step is performed, the APL step is performed before the DHF step.

[0028] In contrast to conventional polymerization, plasma polymerization can be carried out using any type of hydrocarbon gas. Methane (CH 4 ), ethylene (C 2 H 4 ) or acetylene (C 2 H 2 ) are primarily used. The amorphous nature of the adhesion-promoting layer obtained is related to the degree of crosslinking. Regardless of the monomer used, saturated and unsaturated monomers exhibit different deposition rates. As an example, it was found that plasma polymers derived from acetylene appear slightly yellow due to the unsaturated bonds remaining in the film structure. Methane leads to a reduction in the deposition rate. In order to obtain a nitrided hydrocarbon adhesion layer, a reactive gas such as ammonia is mixed with ethane during the plasma process. Other examples of reactive gases are N 2 , CO 2 , CO, and N 2 O.

[0029] For layers subsequently deposited on the fabric (eg deposited in a DHF step or a DLC step), the advantage of an adhesion promoting treatment is that these layers and coatings have better adhesion and are therefore more durable during use of the fabric.

[0030] The hydrocarbon layer acts as an adhesive joint, improving the cohesion of the DHF or DLC. In addition, mixing the reactive gas into the hydrocarbon plasma leads to the introduction of functional groups, which increases the surface energy of the fabric. Therefore, this functionalized surface layer acts as a chemical anchor (bond) with subsequent coatings such as DHF.

[0031] As an alternative to the APL step, the method may further comprise an APT step of producing an adhesion-promoting surface by using plasma etching, ion beam irradiation and / or UV imprinting, wherein the APT step is performed before the DLC step, or if no DLC step is performed, the APT step is performed before the DHF step.

[0032] Plasma etching processes can be used to create patterns ranging from nanometers to micrometers. Stringent requirements regarding etch rate, selectivity, profile control, and surface damage caused by plasma etching processes are at the root of much research in plasma diagnostics and surface analysis, as well as the development of new etching equipment. The key parameters of the plasma-surface interaction vary with each material, depending on the gas mixture and ion bombardment. Typically, the key parameter is the ratio of neutral flux to ion energy flux.

[0033] In plasma etching (also known as reactive ion etching) of organic polymers such as fabrics, a gas mixture of oxygen and tetrafluoromethane (CF4) is used, as an example, to generate oxyfluoride ions (OF - ), and this ion is a highly reactive etchant for polymeric materials (such as monofilaments), particularly for cutting carbon-carbon bonds in the polymer backbone. It has been found that the applied pressure and bias determine the etching effect on the surface topography of the bulk polymer.

[0034] Another ion milling technique is ion beam irradiation, commonly referred to as ion beam milling or ion beam sputtering. It removes material from the target surface by using a focused, precisely defined ion beam, typically composed of inert gas ions such as argon. Ion beam irradiation is a completely physical sputtering process that differs from reactive ion etching in that it does not rely on chemically reactive gases. These ion sources produce a high-density, collimated ion beam with well-controlled energy and direction. The ion beam is directed at the target surface, where the high-energy ions collide with the surface atoms, causing them to be sputtered away. Ion beam etching offers several advantages, such as high etch rates, excellent depth control, and the ability to produce anisotropic etch profiles. Since the process does not involve chemically reactive species, the etching process is relatively clean and not susceptible to contamination.

[0035] UV embossing is also a common method for producing nanostructured surfaces. Additionally or alternatively, prior to deposition in step DHF and / or step DLC, a two-step pretreatment of the polymer fabric can be performed, wherein in a first step, the polymer fabric is coated with a UV-curable embossing resin using a gravure coating and / or slot die coating method, and in a second step, the surface is patterned using UV embossing and / or hot embossing methods.

[0036] When the modified surface is subsequently coated with a DHF step, the etched or irradiated or embossed surface results in good adhesion to subsequent coatings and better water and oil roll-off via mechanical interlocking.

[0037] Preferably, in step DHF, a halogen-free hydrophobic and oleophobic coating is deposited on the fabric with a thickness of 30 nm to 300 nm, preferably 50 nm to 150 nm. It has been shown that a coating within this thickness range is sufficient to provide good oleophobic and hydrophobic properties.

[0038] Advantageously, in step DLC, a hydrophobic carbon coating is deposited on the fabric with a thickness ranging from 5 nm to 200 nm, preferably from 10 nm to 80 nm. Even such a thin coating can significantly improve the adhesion and chemical resistance properties of the fabric.

[0039] Advantageously, in step APL, an adhesion-promoting coating is deposited on the fabric, which has a thickness of 5 nm to 100 nm, preferably 10 nm to 60 nm. The adhesion properties of subsequent coatings can be significantly improved already with such thin layers.

[0040] The advantage of these thin layers is that the mesh size of the fabric is not significantly affected by these coatings in the above steps. As a result, the breathability is hardly impaired.

[0041] In the case of fabrics, plasma treatment can be performed in a plasma chamber with multiple rollers and / or a tenter in a roll-to-roll system. Depending on the electrode arrangement, single-sided or double-sided fabric treatment can be performed. For PECVD, particularly in the DHF, DLC, and / or APL steps, different types of electrodes, such as hollow cathodes, parallel plates, or rotating drums, can be used as the plasma source, connected to one or more of alternating current (AC), direct current (DC), pulsed DC, continuous radio frequency (RF), pulsed RF, and the like.

[0042] The degree of crosslinking of the plasma polymer film strongly depends on the energy input. The power density also depends on the plasma machine configuration, such as the electrode arrangement. For a flat plate or drum electrode arrangement, the plasma power during the DHF and APL steps can be below 1 W / cm 2 Electrode surface, preferably less than 500 mW / cm 2 Electrode surface or more preferably less than 200 mW / cm 2 Electrode surface. For a hollow cathode electrode arrangement, the power density of the plasma can vary from 2.5 kW to 18 kW per linear meter of plasma. In addition to the electrode arrangement used, the concept of gas supply to the reactor chamber is also relevant to the preferred plasma power.

[0043] For PECVD process, the plasma power during the DLC step can be less than 1W / cm2 electrode surface, preferably less than 500mW / cm2. m 2 electrode surface or more preferably less than 200mW / cm 2electrode surface, and for PVD sputtering, the power is 2000 to 8000 mW / cm 2 .

[0044] In a preferred embodiment, the fabric has a filament diameter of 10 μm to 100 μm, particularly preferably 19 μm to 50 μm. Alternatively or in addition, the fabric has a mesh size (space between two adjacent filaments) between 5 μm and 150 μm, particularly preferably 19 μm to 125 μm.

[0045] It has been shown that the filament diameter must not fall below a lower limit, otherwise the capillary effect increases and the oleophobic properties deteriorate significantly. A similar effect occurs with different mesh sizes. Here, too, there is a preferred range where the capillary effect is at its lowest.

[0046] In a preferred embodiment, the plasma-coated textile in the DHF step has hydrophobic properties according to DIN 55660-2:2011-12, corresponding to a water contact angle of 110° to 160°, and oleophobic properties according to a diiodomethane contact angle of 80° to 140° and a hexadecane contact angle of 40° to 120°, and an oil repellency rating of at most 4 according to DIN EN ISO 14419:2010 (or AATCC 118).

[0047] In a further preferred embodiment, the fabric coated in step DLC is chemically inert and resistant to acids, bases and organic solvents and has hydrophobic properties according to DIN 55660-2:2011-12 corresponding to a water contact angle of 90° to 140°.

[0048] In addition to the steps explained above, the method may further include a step (PT) of pre-treating the fabric using an atmospheric pressure or low-pressure plasma with an inert gas and / or reactive gas that does not form a polymer, wherein the step (PT) is performed before the DLC step, or, if the DLC step is not performed, before the DHF step. If the APL step is used, the step (PT) is preferably also performed before it. The APT step may be performed without first performing the PT step.

[0049] In order to clean the fabric and improve adhesion to the plasma coating, the polymer fabric can be pretreated by atmospheric pressure and low pressure plasma techniques using non-polymerizable gases such as argon, helium, nitrogen, oxygen and tetrafluoromethane gas and / or their gas mixtures before depositing the functional layer as in step DHF or DLC. Low pressure plasma pretreatment has several advantages over atmospheric pressure plasma. When driven by an external source (e.g., an RF generator), the gas at low pressure allows free electrons to be accelerated. As a result, highly reactive and activated molecular species, such as chemical free radicals, ions, electrons, etc., can be generated by ionization, fragmentation (dissociation), excitation, UV radiation, etching reactions, etc. These species react chemically and physically with the polymer surface, thereby changing the surface properties and surface morphology in the top layer. Surface activation varies from surface cleaning, free radical formation and atom implantation to surface etching; it depends on different process parameters, such as, for example, energy input. Oxygen-containing gas mixtures (Ar / He and O2) were found to be more effective than pure inert gases (Ar, He, etc.) to remove organic contaminants by oxidizing the polymer surface and by generating plasma degradation products such as hydrogen, water vapor, carbon dioxide, etc.

[0050] In principle, the previously explained steps PT, APL or APT, DLC, and DHF can be performed in any order, and it is possible to perform several steps more than once. In a preferred embodiment, the steps are performed in the following order: step PT, step APL or APT, optional step DLC, and step DHF. It has been recognized that treating an object to be provided with an oleophobic and hydrophobic coating using the steps in the order defined above produces exceptional results.

[0051] Based on the method of the present invention, it is possible to produce a fabric having hydrophobic and oleophobic properties, said fabric comprising a halogen-free plasma coating formed thereon according to standards IEC 62321-3-2: 2020, EN 14582: 2016 and / or ASTM D7359: 2018, in particular free of per- and polyfluorinated substances (PFAS), wherein the fabric comprises a woven monofilament fabric of a polymer material having a filament diameter of 10 μm to 100 μm and a mesh opening of between 5 μm and 200 μm.

[0052] As an example, the fabric can be used as a protective venting element in mobile devices, as a filter for many applications: acoustic venting, ventilation filter, fuel filtration, water separation, clothing, packaging, building and electronic seals / circuit boards, shoes, wound dressings or face masks. The invention further relates to electronic or electrical devices, such as mobile phones, portable media players, high fidelity devices, tablets, laptops, any type of portable device and televisions. The fabric according to the invention can be used for various venting applications in healthcare, such as infusion / transfusion / blood filters, mattresses, pillows, duvets, bed linen, ventilation filters (in and / or out) of (electronic) devices, (surgical) masks, (surgical) gowns, intravenous inline filter sets, pressure filtration devices, in particular in medical devices, indoor ventilation and venting barrier media for industrial applications.

[0053] The fabric according to the invention is preferably a woven monofilament fabric, wherein the filaments are made of the same material. Alternatively, a fabric with filaments of different materials can be used.

[0054] The fabric can be made from and / or comprise one or more of or a combination of the following materials: polyvinylidene chloride (PVDC), polyhexamethylene adipamide (PA 6.6), polydodecanamide (PA 12), polypropylene (PP), polycaprolactam (PA 6), polyethylene terephthalate (PET), ethylene-chlorotrifluoroethylene (E-CTFE), ethylene-tetrafluoroethylene (ETFE), polyethylene (PE), polyoxymethylene (POM), polycaprolactone (PCL), polysulfone (PS), chitosan (CH), polyvinyl butyral (PVB), 1-dodecyltrimethylammonium bromide (DTAB), chlorhexidine (CHX), benzyltrimethylammonium bromide (BTAB), polyacrylate, polyethylene (PE), high-density PE, fluorinated ethylene propylene (FEP), bicomponent (PA 6 / PA 12), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), polyacrylonitrile (acrylic fiber) (PAN), bicomponent PET flame retardant (PET / PBT), polyundecanoamide (PA 11), polyphenylene sulfide (PPS), polyhexamethylene sebacamide (PA 6.10), aramid (AR), polyethylene naphthalate (PEN), polyamide carbon fiber (PA / CF), polyester carbon fiber (PET / CF), polyester staple fiber / metal fiber (PET / MT), carbon fiber (CF), copper (CU), polyimide (P84), copper / silver (CU / AG), polycarbonate (PC), aliphatic polyamide, aromatic polyamide, polyurethane (PU), polyvinyl alcohol (PVA), polylactic acid (PLA), polybenzimidazole (PBI), polyethylene oxide (PEO), polybutylene terephthalate, polyvinyl chloride (PVC), cellulose, cellulose acetate (CA), polypropylene (PP), PVA / silica, PAN / Ti02, PETFE polyetherimide (PEI), polyaniline, polyethylene naphthalate, styrene butadiene rubber, polystyrene, polyvinyl butylene, polymethyl methacrylate (PMMA).

[0055] Plasma technology There is a growing interest in plasma processes, especially low-temperature plasmas, for modifying the surface properties of polymeric materials without changing the bulk properties of the substrate. Plasma technology generates free radicals and oxidizes the surface (i.e., hydrophobic / oleophobic surface); it changes the morphology: the adhesion, repellency, roughening of the surface; it allows the surface to be cleaned, resulting in improved quality for printing, dyeing, painting, etc. In the field of textile finishing, plasma technology shows significant advantages because it is a dry and environmentally friendly method. In addition, due to the wide variety of feed gases that can be used to perform a large number of surface chemistries, a variety of chemical functions can be incorporated into the textile surface to obtain different chemical and physical characteristics. Non-thermal plasma has been widely used in practical industrial needs to provide high-quality, high-productivity, low-cost and environmentally clean surface treatment processes.

[0056] Furthermore, plasma polymerization or plasma deposition processes offer a versatile approach to designing materials with tunable functionalities. The unique properties of plasma polymer smart coatings, such as tunable wettability, self-cleaning, and antireflection, have made them prominent in diverse applications such as biomaterials, drug delivery, adhesion, protective coatings, microelectronics, oil-water separation, and thin-film technologies.

[0057] PECVD process Plasma-enhanced chemical vapor deposition (PECVD) is a suitable polymerization method using precursors in liquid or gaseous form. This highly controlled polymerization method ensures pinhole-free, cross-linked, and dry deposited polymers, and avoids the difficulties encountered in wet chemical polymerization processes, such as uneven coatings and imperfect coatings caused by solvent impurities.

[0058] Compared to traditional polymerization, plasma treatment improves the crosslinking of polymers. To further explain the plasma polymerization method, vaporized monomer precursors are pumped into an evacuated plasma chamber. The energy input subsequently generates excited electrons during a glow discharge process, causing the molecules to break apart into free electrons, ions, free radicals, and excited molecules. These free radicals and excited molecules then recombine, condense, and polymerize on the substrate. The ions and electrons crosslink or form chemical bonds with the deposited polymer. Therefore, the properties of plasma polymers are determined not only by the precursors but also by the deposition parameters.

[0059] The plasma treatment of textiles or other materials can be used as textile finishing process, promptly is used for industrial and medical textiles and is used for composite materials to improve their surface properties such as water repellency and oil repellency.This is also possible for other materials and compact objects.Compared with conventional wet chemical textile finishing, plasma technology demonstrates the advantage about environmental issues.Adopt PECVD to handle, can obtain for example improvement of adhesion properties, improve hydrophilicity / hydrophobicity, introduce special functional groups or change surface morphology from the teeth outwards.

[0060] In plasma deposition (often referred to as plasma polymerization or PECVD), very thin polymer layers (nanoscale) can be deposited on substrate surfaces. This layer is formed by polymerization of an organic precursor gas, which polymerizes directly on the substrate surface. In contrast to conventional polymerization, plasma polymerization can use any monomer gas or vapor, regardless of its reactivity. Plasma polymerization exhibits unconventional polymerization behavior with branched and randomly terminated chains and a high degree of crosslinking.

[0061] The bulk structure of plasma polymers is completely irregular, a far cry from conventional polymers. Plasma polymer coatings (nanofilms) differ from conventional polymers in their high functional group density per unit volume, highly crosslinked and branched plasma polymer networks, nanometer-thick coatings, high adhesion of the coating to the substrate, and no change in the bulk properties of the substrate, which can be a polymer fabric.

[0062] For DHF, APL, APT, DLC processes, there are different types of power supplies that can be used. RF plasma sources are by far the most common. Most RF sources use an industry standard frequency of 13.56 MHz. Of these, there are three main types: capacitively coupled plasma or CCP, also known as reactive ion etcher (RIE); inductively coupled plasma (ICP), also known as transformer coupled plasma (TCP); and helicon wave source, which is novel and can be referred to as HWS. Plasma RF generators generate high power RF signals and are one of the key front-end subsystems of large industrial plasma processing systems. Over the past 20 years or so, the number of applications for industrial plasma processing has exploded, and multiple industries now benefit from the use of plasma processing.

[0063] Pulsed RF power for plasma processing has been introduced as a solution to avoid the problems faced by CW RF power, such as charging damage and reflected power from the chamber. However, the process of delivering pulsed RF power is more complex than that of delivering CW RF power. WO 2001 / 084591 A2 provides a method for overcoming these problems associated with delivering pulsed RF power to a plasma processing chamber.

[0064] DC and low-frequency discharges can operate in continuous and pulsed modes. Pulsed DC power is generated in a highly asymmetric electrode configuration, such as a sharp needle or thin wire opposite a flat or large-diameter cylinder (drum). When a high voltage is applied to the smaller electrode, a strong electric field is generated around it, so the plasma ignites in the form of a streamer.

[0065] While AC plasma generators are considered more efficient and less expensive, prior art AC systems have been found to be inherently unstable. One source of this instability is the fact that if the arc is pulsed in a single-phase system, it extinguishes during each half-cycle. Therefore, the arc must be initiated 120 times per second.

[0066] Test Method To determine halogen concentrations, specifically PFAS concentrations, the following test methods are used. All three standards cover total fluorine (TOF) analysis. Extractable organic fluorine (EOF) is the same as the CIC analysis, but the methanol extract is combusted instead of the sample directly. TOF and EOF results cannot be directly compared; TOF results are typically much higher (approximately 2 to 12 times higher).

[0067] IEC 62321-3-2:2020: Details the use of combustion ion chromatography (CIC) for the screening analysis of fluorine, chlorine, and bromine in polymers and electronic devices.

[0068] EN 14582:2016: This standard details a combustion method for the determination of the halogen and sulfur content in materials by combustion in a closed system (calorimetric bomb) containing oxygen and subsequent analysis of the combustion products using different analytical techniques.

[0069] ASTM D7359:2018: Standard test method for total fluorine, chlorine, and sulfur in aromatic hydrocarbons and their mixtures by oxidative pyrohydrolytic combustion with subsequent ion chromatography (CIC). This method is comparable to the OEKO-TEX STANDARD 100 method.

[0070] In the following, the invention is further described by means of preferred exemplary embodiments schematically illustrated in the accompanying drawings, in which: Figure 1 A combination of schematic flow charts of the method of the present invention, including illustrations of different deposited films on fabrics; Figure 2 A combination of schematic flow charts of the method of the invention, including illustrations of different results on fabrics; and Figure 3 Two AFM images of plasma-etched PEEK fabric exist Figure 1On the left side of FIG. 1 , a schematic flow chart comprising several steps according to the present invention is shown. Figure 1 The right side of FIG. 1 illustrates the deposited layers on the fabric, where only one monofilament is shown for clarity.

[0071] According to this embodiment, step PT is first performed. In this step, a plasma pretreatment is performed on the surface of the fabric, which should be a woven monofilament fabric of the polymer material onto which the various subsequent layers are to be deposited. The plasma treatment is preferably performed in a closed chamber with a low-pressure atmosphere. The purpose of this treatment is to clean the surface of the fabric, making it easier to deposit the subsequent polymer. Depending on the power used, the plasma treatment can also roughen the surface of the substrate, making it easier for subsequent layers to adhere. Sometimes, this roughening is seen as creating microgrooves in the substrate material.

[0072] The PT step may be followed by an APL step or a DHF step to improve the adhesion of subsequent layers.In the APL step, the layers may be deposited on the fabric by plasma polymerization of hydrocarbon gases and / or mixtures of hydrocarbon gases, reactive gases and inert gases.

[0073] As can be seen from the right, after the cleaning of step PT, an APL layer is applied to the fabric.

[0074] After the APL step, a DLC step is optionally performed, in which an amorphous hydrogenated diamond-like carbon coating is deposited onto the previous APL layer. The combination of these two layers (shown only in a very simplified manner on the right) ensures that the entire surface of the substrate is coated. Typically, the layer thickness may not be so constant.

[0075] After the DLC step, a DHF step is carried out, in which a non-fluorinated polymer coating is carried out, which can be based on, for example, organosilanes (trimethylsilane, etc.), siloxanes (hexamethyldisiloxane, divinyltetramethyldisiloxane, tetramethylsilane, etc.), hydrocarbons (methane, ethane, acetylene, etc.) and mixtures thereof.

[0076] Preferably, the object to be coated is kept in a chamber with low pressure or with vacuum during the entire treatment process.

[0077] After carrying out step DHF, the coated object can in principle be used or can be delivered to further processing.

[0078] Figure 2 shows an alternative treatment of the fabric. Figure 1 As for the method steps, the main difference is that the APT step is performed instead of the APL step.

[0079] During the APT step, the surface of the monofilament is roughened, which also improves the adhesion of subsequent layers. This can be achieved by plasma etching, ion beam irradiation and / or UV embossing. A PT step is not necessary before the APT step.

[0080] The other steps of this example correspond to Figure 1 Therefore, step APL and step APT can be regarded as alternatives.

[0081] In view of the oleophobic property, the object to be coated should be a woven monofilament of a polymer material having a filament diameter of 10 μm to 100 μm and a mesh size between 5 μm and 200 μm.

[0082] Fabric used Eight different fabric products have been analyzed in order to find out the influence of the fabric construction in determining the hydrophobic and oleophobic properties. Table 1 summarizes the fabric parameters and characteristics. This information provides a basis for understanding their behavior and developing new materials with specific surface properties. For example, a tightly woven mesh with a very low mesh size of 5 μm and a filament diameter of 34 μm can be seen in fabric A. In contrast, a very open mesh with a mesh size of 200 μm and a filament diameter of 100 μm can be seen in fabric H. In addition, fabrics made of mesh product D, membrane layers and knitted materials with an average pore size of 0.70 μm and a filament diameter of 35 1 / m 2 Composite articles (I) having an air permeability of s@200 Pa. Low surface tension liquids (such as oils) have an enhanced capillary effect on such composite materials. Table 1. Comparative Example Fabric Properties TW is twill weave and PW is plain weave.

[0083] Example 1 Eight different articles coated with a silicone-based coating (DHF) were tested for contact angles of three liquids and subjected to an oil drop test according to DIN 55660-2:2011-12 and DIN EN ISO 14419:2010, respectively. Hydrophobicity was evaluated by measuring the water contact angle, while oleophobicity was determined by measuring the contact angles with diiodomethane and hexadecane and by the oil drop test. As can be seen in Table 2, tightly woven fabrics were found to produce higher capillarity and, therefore, to achieve very low to moderate oil repellency (e.g., Fabric A). In contrast, due to the uneven wicking of low-surface-tension liquids (e.g., oil), good oleophobic surfaces could be achieved by adjusting the mesh openings and yarn diameter (e.g., Fabric CF). Due to droplet penetration, moderate oleophobic modification could be achieved on meshes with large openings (e.g., Fabric GH). These findings indicate that both mesh geometries, in addition to the plasma process, are important parameters that must be considered when performing plasma polymerization of silicone coatings, as the resulting oleophobicity can vary significantly. Table 2. Contact angle and oil repellency rating results for different fabric geometries obtained after the DHF step

[0084] Example 2 It is important to protect the coating from damaging and harsh conditions during application. Grinding forces are an example of a coating that may erode deposits. Therefore, wear resistance is one of the limiting factors that determine the life of the product. In order to ensure that the plasma coating (PT followed by a DHF step) is well bonded to the substrate surface as a multilayer composite membrane material (I), wear tests were performed according to EN ISO 12947 Serie and EN ISO 12945-2. Table 3 shows the significant wear resistance of the coating. The contact angles with the two liquids measured according to DIN 55660-2: 2011-12 were almost unchanged, indicating high coating adhesion to the object. However, we found that the oleophobic properties on the coated composite membrane were quite poor due to the higher capillary effect. The composite membrane according to the present invention can comprise a woven base layer and a superimposed nanofiber layer, such as an electrospun membrane. The electrospun membrane produced is composed of a large number of nanofibers that are interwoven and overlapped with each other to form a fibrous and porous structure inside, resulting in a very high capillary effect with low surface tension liquids (such as oils). Table 3. Contact angles of the two liquids before and after abrasion in the comparative example

[0085] Example 3 To evaluate the water separation efficiency, PT+DHF coated and DHF coated polyester articles were tested according to ISO / TS 16332. As can be seen in Table 4, superior water separation efficiency was achieved with a PT step followed by a DHF step compared to DHF without a pretreatment (PT) step. Table 4. Developed coatings show excellent water separation efficiency fabric Processing Type Water separation top side [%] Water separation bottom side [%] B PT+DHF 93.3 91.6 C DHF 84.5 85.2

[0086] Example 4 To ensure that the DLC coating can be used as an adhesion-promoting layer for the DHF coating and that the resulting coating (DLC+DHF) adheres well to the substrate, an internal washing test was performed at 40°C for 47 minutes. The washing cycles were 0×W: no washing, 1×W: one washing cycle, and 10×W: ten washing cycles. The contact angles with three liquids and the oil drop test were measured according to DIN 55660-2:2011-12 and DIN EN ISO14419:2010, respectively. Table 5 shows the significant washing resistance of the coating. The contact angles with the two liquids decreased slightly, indicating high coating adhesion to the object. It can also be seen that including the DLC coating as a primer for the DHF step results in higher contact angles, meaning that improved washing resistance can be obtained with a DLC step followed by a DHF step. The oil repellency of the washed objects was also evaluated with 8 different liquid oils, and the results showed that the oil repellency only decreased slightly even after 10 washing cycles. Thus, based on the present invention, it is evident from these data that robust and reliable coatings with excellent hydrophobic and oleophobic properties can be obtained on polymeric fabrics. Table 5. Contact angles of two liquids and oil drop test before and after washing in comparative examples

[0087] Example 5 In addition to performance and functionality tests, the coated fabrics according to the present invention were also subjected to tests for coating compliance for medical applications, such as endotoxin and blood compatibility tests.

[0088] Endotoxin testing is performed to determine the usability of the product for medical applications. <85> As can be seen in Table 6, both the DHF-coated and PT+DHF-coated articles contained concentrations less than the endotoxin limit and passed the test.

[0089] Hemocompatibility of materials that come into contact with blood is also one of the most important criteria for medical applications. According to ISO 10993-4 and ISO 10993-12, the interaction between newly developed coating materials and blood has been extensively analyzed to prevent activation and destruction of blood components during application. The hemocompatibility analysis of the coated articles is summarized in Table 6 below, and all coated articles passed the test. Table 6. Endotoxin and blood compatibility tests

[0090] Example 6 Plasma etching was performed using a low-temperature, low-pressure plasma system with a gas mixture of CF4 and oxygen. The etched surface was characterized using AFM. Rq is the root mean square roughness, and Ra is the average roughness. The average roughness is the area between the roughness curve and its mean line. Clearly, direct bias plasma has proven very effective for roughening textile fabrics. The roughness of small maps appears to be more consistent. The roughness of large maps can be affected by large surface features, such as grooves in the map. Table 7. Comparative Examples of Etched Samples Studied by Atomic Force Microscopy (AFM)

[0091] Through AFM images (which show Figure 3 (center) The morphology changes caused by the etching process were further studied. Figure 3 An AFM image of a plasma etched PEEK fabric is shown (direct bias, 500 V). Uniform texturing and roughening of the PEEK surface due to the etching conditions can be seen.

[0092] Example 7 Coated samples were screened for total fluorine content, including perfluoroalkyl and polyfluoroalkyl substances (PFAS), according to IEC 62321-3-2:2020. Results can include inorganic and / or organic fluorine content. It's possible that the total fluorine content is not derived from PFAS. Clearly, all treatment steps (PT, APT, APL, PT, DLC, DHF) and their combinations are PFAS-free.

[0093] Table 8 shows that no PFAS (eg, fluorine) were detected on the hydrophobic and oleophobic coated fabrics. Table 8. PFAS detection according to IEC 62321-3-2:2020 fabric Processing Type Limit Unit(s) MDL PFAS test results expressed as fluorine A DHF 50 mg / kg 20 ND C DLC+DHF 50 mg / kg 20 ND E PT+DHF 50 mg / kg 20 ND I APL+DHF 50 mg / kg 20 ND I APT+DHL 50 mg / kg 20 ND Where 1mg / kg = 1ppm = 0.0001% MDL = Method Detection Limit ND=Not Detected( <MDL)

[0094] Example 8 The contact angles of two liquids and the oil drop test were measured according to DIN 55660-2:2011-12 and DIN EN ISO 14419:2010, respectively, on articles etched using an APT procedure and subsequently coated with a silicone-based coating (DHF). Measurements were performed before and after the abrasion test. Table 9 shows the coating's remarkable abrasion resistance. The contact angles with both liquids remained unchanged, indicating high coating adhesion to the object. However, the oleophobic properties on the coated substrate were found to be quite poor due to the droplets penetrating the very large mesh pores. Table 9. Contact angles with two liquids before and after wear testing and oil drop test for comparative examples

[0095] Example 9 To ensure that DLC coatings, when used as undercoats for DHF, improve the chemical resistance of the resulting coating (DLC + DHF) compared to DHF alone, an in-house chemical immersion test was performed at room temperature. The samples were immersed in an acidic environment at approximately pH 1 for 0, 15, 30, 60, and 90 minutes. After the chemical treatment, the samples were dried, and the contact angles with the two liquids were measured according to DIN 55660-2:2011-12.

[0096] The considerable chemical resistance of the DLC+DHF step compared to DHF alone is shown in Table 10. It can be clearly seen that higher contact angles are obtained on the DLC+DHF coated and chemically treated samples compared to the DHF coating, which means that improved chemical resistance can be obtained with a DLC step followed by a DHF step. Table 10. Contact angles of the two liquids before and after the comparative chemical test

[0097] Example 10 The oil drop test was carried out in accordance with DIN EN ISO 14419: 2010 on articles coated once with a silicone-based coating alone (DHF) and once with a DLC step followed by a DHF step. The measurements were carried out before and after the immersion test in alkaline and acidic media at different treatment times, as described in Example 9.

[0098] As can be seen in Table 11, the oil repellency rating tends to decrease significantly, regardless of the chemical nature of the medium (acid or base), unless we include a DLC step before the DHF step. This demonstrates that the DLC step can improve the chemical stability of the resulting coating when performed before the DHF step. Table 11. Oil drop test before and after chemical testing of comparative examples

[0099] Based on the present invention, it is possible to provide a method for producing a fabric having hydrophobic and oleophobic properties, said fabric having a halogen-free plasma coating according to standards IEC 62321-3-2: 2020, EN 14582: 2016 and / or ASTM D7359: 2018, in particular free of per- and polyfluorinated substances (PFAS), as well as a fabric having hydrophobic and oleophobic properties, said fabric comprising a halogen-free plasma coating, in particular free of per- and polyfluorinated substances (PFAS).

Claims

1. A method for producing a fabric having hydrophobic and oleophobic properties, said fabric having a halogen-free plasma coating according to standards IEC 62321-3-2: 2020, EN 14582: 2016 and / or ASTM D7359: 2018, in particular free of per- and polyfluorinated substances (PFAS), wherein said method comprises: a step DHF of depositing a plasma coating on said fabric by plasma enhanced chemical vapor deposition (PECVD) by means of plasma polymerization of halogen-free precursor monomers, wherein the halogen-free precursor monomer is an organosilane, siloxane and / or hydrocarbon precursor, wherein the plasma enhanced chemical vapor deposition is carried out as a low pressure plasma process under a protective atmosphere, The fabric comprises a woven monofilament fabric of a polymer material having a filament diameter of 10 μm to 100 μm and a mesh opening between 5 μm and 200 μm.

2. The method according to claim 1, comprising the step of coating the fabric DLC by a PVD method using an argon plasma sputtering carbon target and / or by a PECVD method using hydrocarbon gas, The step DLC is performed before the step DHF.

3. The method according to claim 1 , comprising an APL step of producing the adhesion-promoting layer by plasma polymerization of a hydrocarbon gas and / or a mixture of a hydrocarbon gas, a reactive gas and an inert gas, The APL step is performed before the DHF step or before the DLC step.

4. The method according to claim 1 , comprising an APT step of producing an adhesion promoting surface by using plasma etching, ion beam irradiation and / or UV imprinting, The APT step is performed before the DHF step or before the DLC step.

5. The method according to claim 1, wherein in the step DHF, a halogen-free hydrophobic and oleophobic coating is deposited on the fabric, which has a thickness of 30 nm to 300 nm.

6. The method according to claim 1, wherein in the step DLC, a hydrophobic carbon coating is deposited on the fabric having a thickness of 5 nm to 200 nm.

7. The method according to claim 1, wherein in step APL, an adhesion promoting coating is deposited on the fabric having a thickness of 5 nm to 100 nm. 8 . The method according to claim 1 , wherein the fabric has a filament diameter of 10 μm to 100 μm, particularly preferably 19 μm to 50 μm. 9 . The method according to claim 1 , wherein the fabric has a mesh size of 5 μm to 200 μm, particularly preferably 19 μm to 125 μm.

10. The method according to claim 1, wherein the plasma-coated textile in the DHF step has hydrophobic properties according to DIN 55660-2:2011-12, corresponding to a water contact angle of 110° to 160°, and oleophobic properties according to DIN 55660-2:2011-12, corresponding to a diiodomethane contact angle of 80° to 140° and to a hexadecane contact angle of 40° to 120°, and an oil repellency class of at most 4 according to DIN EN ISO 14419:2010.

11. The method according to claim 1, wherein the fabric coated in the DLC step is chemically inert and resistant to acids, bases and organic solvents and has hydrophobic properties according to DIN 55660-2:2011-12 corresponding to a water contact angle of 90° to 140°.

12. The method according to claim 1, further comprising a step PT of pretreating the fabric by atmospheric pressure or low pressure plasma using an inert gas and / or reactive gas that does not form a polymer, wherein the step PT is performed as a first step before the step DHF or DLC or APL.

13. The method according to claim 1, wherein the steps are performed in the following order: 1.PT, 2.APL or APT, 3. Optional DLC, and 4.DHF.

14. A textile having hydrophobic and oleophobic properties obtained by the process according to claim 1, comprising a halogen-free plasma coating according to standards IEC 62321-3-2: 2020, EN 14582: 2016 and / or ASTM D7359: 2018, in particular free of per- and polyfluorinated substances (PFAS), formed thereon. The fabric comprises a woven monofilament fabric of a polymer material having a filament diameter of 10 μm to 100 μm and a mesh opening between 5 μm and 200 μm.

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