Polymeric fabric

The present invention relates to a polymeric fabric having hydrophobic and oleophobic properties and to a method for producing a polymeric fabric having hydrophobic and oleophobic properties.Furthermore, the present invention relates to an apparatus for producing a polymeric fabric.

In microfiltration applications, there is a great demand for the protection of ventilated facilities, equipment and accessories. One of the challenges here is to prevent harmful liquids, particles from entering the interior of the ventilated facility. Liquid-repellent coatings are therefore becoming more and more frequently used in many fields, as they are able to repel a wide range of liquids, from high surface tension liquids such as water to low surface tension oils.

Traditionally, long molecular chain, e.g., C8 fluorocarbon (FC) compounds are used in coatings to protect humans from everyday substances such as water, oil, fuel, lubricants, cleaning solvents, and other contaminants, as well as military chemical agents. However, due to their potentially high toxicity, legislation is in place around the world that restricts or prohibits their use. Alternative coatings are being developed and commercialized. In particular, short chain C6 fluorochemical coatings are approaching the performance of traditional C8-based FC coatings without the high environmental risks.

The use of C6 fluorocarbon-based coatings still leads to global environmental pollution due to the presence of trace amounts of perfluorooctanoic acid (PFOA) and its salts, raising concerns due to the persistence and bioaccumulation potential of these substances. Furthermore, the new REACH regulation (EU/784/2020), effective from December 3, 2020, allows the PFOA threshold to be kept below 25 ppb (parts per billion). Therefore, for health reasons, it is a general trend to avoid these chemicals. In addition, there is still a demand for next-generation superhydrophobic and oleophobic coatings with high repellency against oils and fats.

Hexamethyldisiloxane (HMDSO) is one industrial choice as an alternative to C6 fluorocarbons because it is a non-toxic material and no harmful materials are produced during processing. It is widely used as a precursor monomer for plasma processes due to its suitable vapor pressure. Carbon-rich plasma polymerized HMDSO (pp-HMDSO) from pure HMDSO shows promising mechanical properties such as low internal stress, good adhesion, and excellent hydrophobic barrier performance. Although the water resistance provided by pp-HMDSO coating is promising, pp-HMDSO coating does not provide oleophobicity.

As technological development of thin film technology progresses, there remains a continuing need to develop chemical vapor deposition processes to create thin films of permanent hydrophobic and oleophobic functional groups using ultrashort-chain PFASs that exhibit unique functional properties for filtration applications. The lack of suitable volatile precursors and the difficulty in controlling the composition of the coatings are the major obstacles slowing the realization of this goal.

<p>It is therefore an object of the present invention to provide a robust and reliable hydrophobic and oleophobic fabric for water separation, acoustic, medical, healthcare, food, hygiene and filtration applications, a method for producing the fabric, and an apparatus for producing the polymeric fabric.</p>

<p>According to the invention, this object is achieved on the one hand by a polymer fabric having the features of claim 1, a method for producing a polymer fabric having the features of claim 9 as well as an apparatus for producing a polymer fabric having the features of claim 14.</p><p>Preferred embodiments of the invention are set forth in the respective dependent claims.</p><p>The polymeric fabric according to the invention comprises an outer functional layer having hydrophobic and oleophobic properties made from a first compound and a second functional layer having hydrophobic properties made from a second compound, the first compound and the second compound being different from each other, and the outer functional layer at least partially covers the second functional layer.</p><p>Furthermore, the method according to the invention for producing a polymeric textile is characterized in that an outer functional layer providing hydrophobicity and oleophobicity is deposited on the polymeric textile by a low pressure plasma coating technique and a second functional layer providing hydrophobicity is deposited on the polymeric textile by a low pressure plasma coating technique, the outer functional layer and the second functional layer being different from each other. In addition, before the outer functional layer is deposited on the polymeric textile, the second functional layer is deposited on the polymeric textile, the outer functional layer at least partially covering the second layer.</p><p>The basic idea of the present invention is to move away from the current system of providing a fabric with layers that have all the required characteristics or properties. Based on the present invention, two layers are provided on top of each other, and the layers are different from each other. This allows the selection of different layers with different characteristics. Thus, it is no longer necessary to find and use a material that provides all the required characteristics, but to combine different materials in different layers so that the combination provides the required characteristics.</p><p>It is preferred that the second functional layer does not have oleophobic properties, so that it is clearly different from the outer functional layer, which provides hydrophobic and oleophobic properties. However, due to the overlapping of these two layers, for example, the hydrophobicity of the outer layer does not have to be at a very high level, since the second functional layer, which also provides hydrophobic properties, is placed underneath.</p><p>In an embodiment, the outer functional layer is a plasma nanocoating based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) containing only one, two or three carbon atoms and/or based on perfluoropolyether compounds (PFPE). In yet another embodiment or combination, the second functional layer is a plasma nanocoating based on hexamethyldisiloxane (HMDSO) or a diamond-like carbon (DLC) layer.</p><p>As mentioned above, the use of short chain C6 fluorocarbon (FC) compounds is problematic and, in some regions, is no longer permitted. The straightforward step of replacing C6 fluorocarbon (FC) compounds with ultra-short chain C3-C1 fluorocarbons (FC) such as per- and polyfluoroalkyl substances (PFAS) seems at first glance to be a promising solution. However, although these compounds provide hydrophobicity and oleophobicity in principle, it was found that problems arise when these compounds are deposited on textiles using plasma nanocoating. During the process of plasma polymer coating, the thickness of the PFAS-based C3-C1 fluorocarbon (FC) layer is very thin compared to previous C6-C8-based fluorocarbon (FC) layers. Thus, the layer provided especially on textiles, e.g. woven fabrics, is only an insufficient layer and does not provide a demonstrable hydrophobicity. Surprisingly, it was found that even a thin layer provides good oleophobicity.</p><p>This was also observed when analyzing layers produced by the process of plasma polymer coatings based on perfluoropolyether compounds (PFPEs).However, the advantage of perfluoropolyether compounds compared to plasma nanocoatings based on perfluoroalkyl and polyfluoroalkyl substances (PFASs) containing only one, two or three carbon atoms is that perfluoropolyether compounds (PFPEs) are more environmentally friendly.</p><p>According to the present invention, the outer functional layer is a plasma nanocoating based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) containing only one, two or three carbon atoms and/or based on perfluoropolyether compounds (PFPE), which is applied on a second functional layer having hydrophobic properties. Thus, the unprovable hydrophobicity of the outer functional layer can be improved by the second functional layer of the present invention. In other words, first a layer with good hydrophobic properties is deposited on the fabric, and then in a second further step, an outer functional layer with hydrophobic and oleophobic properties is deposited on the fabric already covered by the second functional layer. This configuration provides the fabric with excellent hydrophobic and oleophobic properties.</p><p>The second functional layer may be based on a hexamethyldisiloxane (HMDSO) or diamond-like carbon (DLC) layer. By using plasma polymer coating, the second functional layer can be formed as a pp-HMDSO-based coating, i.e., a poly(dimethylsiloxane)-like (PDMS-like) coating, a fluorine-doped pp-HMDSO coating, and/or a fluorine-doped DLC coating. These coatings, when deposited by plasma polymer techniques, have a sufficiently good deposition rate to create a layer thicker than the outer functional layer mentioned above. Thus, the combination of these two layer techniques can provide excellent hydrophobicity and oleophobicity to the polymer fabric by polymer plasma coating.</p><p>The outer functional layer and/or the second functional layer are preferably deposited by a low pressure plasma coating technique, also known as plasma enhanced chemical vapor deposition (PECVD). This technique uses low temperature plasma. Therefore, this technique is suitable for temperature sensitive polymeric materials such as monofilament meshes, composite membranes, etc. PECVD allows the deposition of highly cross-linked polymer networks with functional groups incorporated into the network, thus resulting in high long-term stability of the modified surface.</p><p>In general, the polymer fabric can be any type of fabric. In one embodiment, the polymer fabric comprises a woven carrier layer that is a weave of a first monofilament yarn and a second monofilament yarn, the first monofilament yarn and the second monofilament yarn being made of the same or different polymer materials. The provided monofilament yarn is particularly suitable for the proposed plasma-based deposition process.</p><p>To improve the filter properties of the polymeric fabric, the polymeric fabric can include a composite membrane including at least a woven carrier layer and an electrospun membrane layer. The electrospun membrane layer can have a pore size of 0.20 μm to 2.0 μm. The membrane layer can be spun directly onto the woven carrier layer or spun onto a substrate and later transferred to the woven carrier layer during a bonding process.</p><p>As explained, the thickness of the outer functional layer is smaller than that of the second functional layer. If the ratio of the thickness of the second functional layer to the thickness of the outer functional layer is about 2:1, 3:1 or more, excellent hydrophobicity and oleophobicity can be achieved. For example, the second functional layer can have a layer thickness of 20 to 300 nm, and the outer functional layer can preferably have a layer thickness of 10 to 150 nm.</p><p>According to the method of the present invention for producing a polymeric textile, an outer functional layer providing hydrophobicity and oleophobicity is deposited on the polymeric textile by a low pressure plasma coating technique, and a second functional layer providing hydrophobicity is deposited on the polymeric textile by a low pressure plasma coating technique, the outer functional layer and the second functional layer being different from each other, in addition, the second functional layer is deposited on the polymeric textile before the outer functional layer is deposited on the polymeric textile, and the outer functional layer at least partially covers the second functional layer.</p><p>The central idea of the present invention is to provide two different layers, one of which at least partially overlaps the other.This allows the characteristics of the outer functional layer to be supported by the characteristics of the second functional layer.Therefore, it is necessary to use only one compound that has all the necessary characteristics to achieve excellent results, namely, excellent results in terms of imparting hydrophobicity and oleophobicity to polymeric fabrics.This is especially true when the outer functional layer is based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) that contain only one, two or three carbon atoms and/or based on perfluoropolyether compounds (PFPE), which are more environmentally friendly than the compounds that have been used before, but have relatively poor hydrophobicity and oleophobicity.</p><p>To improve adhesion with the second functional layer, the polymeric fabric can be pretreated by low pressure plasma techniques using non-polymerizable gases such as argon, helium, nitrogen, oxygen, and tetrafluoromethane gas, and/or mixtures thereof, prior to deposition of the second functional layer.</p><p>Additionally or alternatively, prior to deposition of the second functional layer, a two-step pretreatment of the polymer fabric can be performed, in a first step, by coating the polymer fabric with a UV-curable imprinting resin using gravure and/or slot die coating methods, and in a second step, by surface patterning using UV imprinting and/or thermal embossing methods.</p><p>Finally, in addition to or instead of the pretreatment described above, the polymer fabric can be pretreated prior to deposition of the second functional layer, in which the polymer fabric is treated with an aqueous solution containing sodium hydroxide (NaOH).</p><p>The pretreatment allows the surface of the textile to be chemically and/or morphologically modified prior to the deposition of the functional layer, so that during plasma polymerization the plasma polymer can stick particularly well to the substrate. Furthermore, surface structuring to improve the roll-off effect, the so-called lotus effect, can also be achieved by nanoimprinting and plasma pretreatment. One or a combination of the pretreatments allows cleaning, activation and/or texturing of the polymer textile, so that the adhesion of the second functional layer can be improved. According to the invention, the pretreatment or cleaning of the textile is not considered as the creation of a layer on the textile.</p><p>According to an improved embodiment, the outer functional layer and/or the second functional layer are deposited in one processing step in one process to obtain a fluorine-doped HMDSO plasma nanocoating and/or a fluorine-doped DLC plasma nanocoating.</p><p>According to the present invention, a polymeric fabric can be provided that has improved water resistance and oil repellency and/or contact angles with water, diiodomethane and pentanediol of 110°-150° and oil grade of 5-8 according to AATCC118.</p><p>The inventive apparatus for producing the inventive polymeric fabric comprises a low-pressure plasma coating device configured to deposit an outer functional layer providing hydrophobicity and oleophobicity onto the polymeric fabric by a low-pressure plasma coating technique, and configured to deposit a second functional layer providing hydrophobicity onto the polymeric fabric by a low-pressure plasma coating technique, the outer functional layer and the second functional layer being different from each other, and the low-pressure plasma coating device configured to first deposit the second functional layer onto the polymeric fabric and then deposit the outer functional layer onto the polymeric fabric, the outer functional layer at least partially covering the second functional layer.</p><p>In the following the invention will be further explained by means of preferred exemplary embodiments which are illustrated diagrammatically in the attached drawings.</p>

<figref num="1">FIG. 1 is a schematic diagram of a polymer fabric.</figref><figref num="2">FIG. 1 is a schematic cross-sectional view of a polymeric fabric according to the present invention that includes a membrane ("monolayer").</figref><figref num="3">FIG. 1 is a schematic cross-sectional view of a composite material according to the invention in a so-called "sandwich" configuration.</figref><figref num="4">FIG. 1 is a schematic cross-sectional view of a composite material according to the invention having a multi-layer structure ("Multilayer").</figref><figref num="5">FIG. 2 is a schematic cross-sectional view of a composite material according to the invention in a "hybrid" configuration having two different carrier layers.</figref><figref num="6">FIG. 1 is a schematic diagram of a method for making the polymeric fabric of the present invention.</figref>

1 is a highly schematic illustration of a polymeric fabric 100. On the left side of the figure, the polymeric fabric 100 is provided with only an outer functional layer 120, whereas on the right side, in addition to the outer functional layer 120, a second functional layer 110 is provided. In the following, the inventive concept will be further explained on the basis of this example.

In FIG. 1, a greatly enlarged schematic diagram of a polymeric fabric 100 is shown, showing two weft yarns 102 and one warp yarn 104 .

As shown on the left, when depositing a PFAS-based first polymer containing 1-3 carbon atoms, the layer does not completely cover the yarns due to the non-optimal deposition rate of this compound. This is especially seen in the contact area between the weft yarn 102 and the warp yarn 104 on the left. The same result occurs when depositing a PFPE-based first polymer instead of a PFAS containing 1-3 carbon atoms.

Conversely, in addition to the outer functional layer 120, a second functional layer 110, for example based on HMDSO, is applied before applying the outer functional layer 120 to ensure that the textile 100 is completely covered by the second functional layer 110. On the one hand, a better deposition of the outer functional layer 120 can be achieved, and on the other hand, even if an area is not covered by the outer functional layer 120, it is at least covered by the second functional layer 110. Instead of the second functional layer 110 of HMDSO, this layer may also be based on F-doped HMDSO, DLC, F-doped DLC, or a combination thereof.

2 is a cross-sectional view of a polymer fabric as a composite material 10 with a carrier layer 11. A membrane 12 formed by electrospinning is placed on the carrier layer 11 and applied. To improve the adhesion of the membrane 12 to the carrier layer 11, the composite material can be designed with at least one connection point 13 that firmly connects both layers to each other. This connection point 13 can be a welding or adhesive bonding location in the form of a point or line. The small layer thickness of the carrier material 11 and the membrane 12 allows the connection point 13 to completely penetrate the composite material at the connection location.

The composite material 10, more particularly the electrospun membrane 12, can be provided with pores. The surface of the composite material 10 and the fibers of the pores can be covered with a coating applied by the two-step plasma coating method of the present invention described with reference to FIG. 1. Thereby, a first plasma coating of pp-HMDSO or DLC is applied to provide only hydrophobicity. Then, a further plasma coating is applied to provide a PFAS-based and/or PFPE-based layer containing only one, two or three carbon atoms to provide hydrophobicity and oleophobicity. The outer functional layer and the second functional layer can also be deposited in one plasma treatment step to obtain a fluorine-doped HMDSO or fluorine-doped DLC layer providing hydrophobicity and oleophobicity. Optionally, F-doped HMDSO or F-doped DLC can be used as the second functional layer.

The surface coating of the fibers is generally indicated diagrammatically in the drawing by the illustrated dots and lines 14. The coating can also cover the fibers in areas within the pores of the membrane 12 located within or deep within the composite material 10. Thus, not only can the visible outer surface of the composite material be coated, but also the invisible inner surface, i.e., for example, the fibers, recesses, and irregularities, where single fibers are individually wrapped or surrounded.

3 shows a further composite material 10 in a so-called "sandwich" arrangement. Here, a membrane 12 is arranged between two carrier layers 11, whereby the membrane 12 is protected in particular from mechanical stress between the layers. In an embodiment of the sandwich arrangement, for example, the membrane 12 has a viscosity of 15.6 l/m at 200 Pa.²s. Basically, a sandwich, multi-layer or hybrid configuration can achieve a breathability of up to 80 l/m at 200 Pa.²It can also reach a breathability of s.

In all possible arrangements of the layers of the composite material 10, these layers can be arranged on top of one another by simple lamination, but the layers can also be firmly connected to one another by connection points 13, which allows a particularly assured mechanical strength of the composite material 10 to be obtained.

In FIG. 4, a multi-layer arrangement (multilayer) of a composite material 10 is shown. In this arrangement, carrier layers 11 and membrane layers 12 are provided so as to be supported on top of one another. According to FIG. 4, two carrier layers 11 and two membrane layers 12 are provided. The multi-layer arrangement may have any number of carrier layers 11 and/or membrane layers 12. If necessary, two membrane layers 12 may be provided directly on top of one another between two or more carrier layers. Even in the case of a multi-layer arrangement, the two-step plasma coating of the invention can be applied to the invisible surfaces of all membrane layers 12 and carrier layers 11 supported on top of one another. Thus, even in a multi-layer structure, the two-step plasma coating of the invention can be applied to the inner surface of the composite material 10.

FIG. 5 shows a variant of the composite material 10, in which the membrane 12 is arranged between a first carrier layer 11 and a second carrier layer 15. Basically, the first carrier layer 11 can be designed in particular as a fabric, and the second carrier layer 15 can be different from the first carrier layer 11 and can be provided in particular as a fleece. Such a "hybrid" arrangement allows the properties of different materials to be advantageously combined in the composite material, so that filtering, protection and sound transmission properties can be advantageously realized in the composite material 10. Also in the hybrid arrangement shown in FIG. 5, the composite material 10 can be subjected to the two-step plasma coating of the invention, in which case the plasma polymerization of the second functional layer and the outer functional layer can take place in deeper layers in the composite material 10, such as in the openings of the pores.

The schematic diagram in Figure 6 shows an example of a manufacturing process for a polymeric fabric of the invention, such as a composite material including a carrier layer. A collecting substrate (top diagram) is provided (first manufacturing step) on which an electrospun membrane is formed. The electrospun membrane is formed according to generally known concepts, as further described below.

In a second step, the formed membrane is transferred and bonded to a carrier layer (bonding 1) and the original collecting substrate on which the electrospun membrane was formed can optionally be removed (collecting substrate removal). According to the illustration above, the carrier layer can be a mesh or a fabric.

Optionally, a second bond (bond 2) can be performed after the introduction of the second outer layer, followed by an optional calendaring process. Thus, the membrane can be placed between two equal or different layers forming a sandwich structure, as the case may be. The second outer layer can be provided, for example, as a mesh, lining, or non-woven material. Finally, a two-step plasma coating of the invention is applied to at least one carrier layer and the membrane. This deposits a first layer that provides only hydrophobicity and a second layer that provides hydrophobicity and oleophobicity. The first layer can be a pp-HMDSO, fluorine-doped HMDSO, DLC, or fluorine-doped DLC layer. The further outer layer can be a PFAS-based and/or PFPE-based layer that contains only one, two, or three carbon atoms.

Processes for making electrospun nanofiber webs are described in WO2006/131081 and WO2008/106903.

Briefly, in the electrospinning process, a high voltage is used to eject or melt a charged polymer solution from a pipette. Before reaching a collection screen, the ejected solution evaporates or solidifies and is collected as a web of fine, interconnected fibers. One electrode is placed in the spinning solution/melt, and the other is attached to a collector. Often the collector is simply grounded. An electric field is applied to the end of a capillary tube, which contains the solution held together by surface tension. This induces a charge on the surface of the liquid. Mutual charge repulsion and contraction of the surface charge against the counter electrode cause a force that opposes the surface tension. As the electric field strength increases, the hemispherical surface of the fluid at the tip of the capillary stretches, forming a conical shape called a Taylor cone. Further increasing the electric field reaches a critical value where the electrostatic repulsion overcomes the surface tension, and the charged fluid is ejected from the tip of the Taylor cone. The ejected polymer solution undergoes an instability and stretching process, becoming very long and thin. The solvent then evaporates, leaving behind a charged polymer fiber. In the case of a melt, the injected melt solidifies as it travels through the air.

Bonding Methods A variety of bonding techniques can be used, including hot melt gravure lamination, ultrasonic bonding, dip bonding, UFD fiberized spray technology (hot melt), and spun web bonding.

Hot melt gravure lamination technology is industrially established for in-line processes. Therefore, for "sandwich" type membranes, two-step bonding can also be done in one line. This technology uses a versatile hot melt lamination and coating system consisting of a gravure roller for dot coating, a revolver dosing head (positive/positive or negative/negative) and an application roller and a lamination roller and a counter pressure roller.

Two different reactive PU-based adhesives (one for PU electrospun membranes, the other for PA6 membranes) can be used by dot-coating the adhesive using a gravure roller. High bond strength can be obtained with a breathability loss of about 15-25%. The adhesives must be carefully selected (for compatibility, physical and chemical compatibility, medical and food grade, etc.) to avoid problems during the final pasting of the membrane. Hardening of the material by the adhesive is observed.

Dip bonding techniques (chemical bonding) can be used to pre-treat the carrier prior to the electrospinning process, and may be preferred in some cases. A major advantage is that it avoids an additional process step for bonding. The two-ply laminate can then be used for a second bond, e.g., hot melt, spun web, UFD, etc., to form a multi-layer vent.

UFD is a fiberized spray technology and is the state of the art for hot melt adhesive application. Laminated plate technology (LPT) is applied to produce filament strands of adhesive. Heated air is used to stretch the strands and arrange them in regular or irregular patterns. In many cases, UFD technology allows for a 20-50% reduction in adhesive usage, without bond strength or durability being adversely affected, due to the high precision application of adhesive. A non-contact mode can be used, which results in less chance of damage to the electrospun fibers during lamination. UFD technology is a cleaner process than hot melt gravure lamination.

The spun web bonding technique results in a three-dimensional structure rather than a membrane with a closed surface. The open structure results in a laminate that is more flexible and breathable. The webs are made from a variety of materials such as copolyamides, copolyesters, copolyolefins, and polyurethanes. The spun web technique is a very simple process. The three main parameters to consider during lamination are temperature, pressure, and time.

Calendering Calendering is used on materials such as fabrics, meshes, and laminated ventilators to produce a smoother, thinner material. It involves passing the material between or under rollers at high temperature and pressure. Depending on the calendering conditions, the size and shape of the pores can be affected.

Plasma PECVDIn order to improve the surface properties such as water and oil repellency of industrial and medical textiles and composites, plasma treatment of textile materials can be carried out as a textile finishing process.Compared with traditional wet chemical textile finishing, plasma technology has advantages in terms of environmental issues.PECVD treatment can achieve, for example, improved adhesion, improved hydrophobicity, introduction of special functional groups on the surface, or modification of surface morphology.

Plasma deposition, commonly known as plasma polymerization or PECVD, allows the deposition of very thin polymer layers (nanoscale) on substrate surfaces. The layers are formed by polymerization of organic precursor gases that are polymerized directly onto the substrate surface. In contrast to conventional polymerization, plasma polymerization can use any monomer gas or vapor, without limitations on its reactivity. Plasma polymers exhibit unconventional polymerization behavior with branched and randomly terminated chains and a high degree of cross-linking.

The bulk structure of plasma polymers is completely disordered, far from the bulk structure of conventional polymers. Plasma polymer coatings (nano-thin films) differ from conventional polymers by high density of functional groups per volume, highly cross-linked branched plasma polymer networks, nanometer thickness of coatings (&lt;200 nm), high adhesion of the coating to the substrate, and no change in the bulk properties of the substrate, which can be a polymer fabric.

According to the present invention, plasma processing can be performed in a plasma chamber having multiple rollers and/or expanders within a roll rotating system operated by radio frequency, preferably about 13 MHz to 14 MHz, preferably about 13.5 MHz, or by a direct current (DC) power source.

One mode for carrying out the invention may be to first carry out a pretreatment, preferably for about 2 minutes to about 5 minutes, at a base pressure of preferably about 70 mTorr to about 200 mTorr, at a temperature of preferably about 20°C to a maximum of about 60°C, and at a power output of preferably about 500 Watts to about 1800 Watts. Then, a first coating step is carried out, preferably for about 2 minutes to about 5 minutes, at a base pressure of preferably about 15 mTorr to about 150 mTorr, at a temperature of preferably about 20°C to a maximum of about 60°C, and at a power output of preferably about 100 Watts to about 1000 Watts. Then, a second coating step is carried out, preferably for about 2 minutes to about 5 minutes, at a base pressure of preferably about 15 mTorr to about 150 mTorr, at a temperature of preferably about 20°C to a maximum of about 60°C, and at a power output of preferably about 100 Watts to about 800 Watts to deposit an outer functional layer. In this embodiment, the outer functional layer is based on a C1-C3 based PFAS and the second functional layer is based on HMDSO or DLC.

<p>The preferred embodiment of the fabric-based filtration media according to the present invention includes a weave structure with different patterns to obtain the highest liquid repellency, thus obtaining a superhydrophobic and oleophobic surface with a contact angle of more than 110°, as seen in Table 1. The degree of plasma-induced hydrophobicity and oleophobicity is also related to the fabric structure and weave configuration. Higher liquid repellency is possible when plasma species penetrate into the fabric structure. Thus, the hydrophobicity and oleophobicity of the substrate are also determined by the arrangement of both the weft and warp filaments of the fabric, the final filament fineness, the fabric density and weave configuration, and the fiber content.</p><p><tables><img file="JP7493009B2_D0001.tif" /></tables></p>

<p>The oil repellency of the treated polymer fabrics was also assessed in parallel by AATCC 118, which is also a "pass/fail" type method that tests for oil repellency rather than water-based liquids. AATCC 118 uses eight liquid hydrocarbons with decreasing surface tension to determine oil repellency. The oil scale ranges from 0 (no) using Kaydol, a mineral oil with a surface tension of 31.5 mN/m at 25°C, to 8 (best oil repellency) using n-heptane with a surface tension of 19.8 mN/m at 25°C. The number given to the oil that does not wet the sample is considered the oil repellency grade.</p><p><tables><img file="JP7493009B2_D0002.tif" /></tables> As can be seen from Table 2, similar and better results can be obtained by using the coating of the present invention compared to the standard coating based on C6. This finding can be explained as follows: the physical modification improves the roll-off effect; the PDMS-like coating (i.e. pp-HMDSO) is enhanced to obtain good water repellency, and the fluorinated top coating is effective against oil, fat, and milk.</p><p>Based on the present invention, it is also possible to produce polymeric fabrics for filtration media, in which the hydrophobic and oleophobic groups embedded in the fabric are stable and resistant to accelerated aging treatment according to ASTM F1980-16. Furthermore, the two-step hydrophobic and oleophobic nanocoating of the filtration media has excellent water and oil repellency according to ISO 4920 and AATCC 118, respectively.</p><p>Based on the present invention, a robust and reliable fabric having hydrophobic and oleophobic properties can be provided.</p>