Polymeric fabric

The present invention relates to hydrophobic and oleophobic polymeric fabrics and methods of making hydrophobic and oleophobic polymeric fabrics. Furthermore, the invention relates to an apparatus for manufacturing polymer fabrics.

Microfiltration applications place great demands on the protection of ventilated premises, equipment and accessories. One of the challenges here is to prevent harmful liquids and particles from entering the interior of the ventilated facility. Therefore, liquid-repellent coatings are frequently used in many fields because they can repel a wide range of liquids, from high surface tension liquids such as water to low surface tension oils.

Traditionally, long-molecular chains, such as C8 fluorocarbon (FC) compounds, have been used to protect humans not only from military chemicals, but also from everyday substances such as water, oils, fuels, lubricants, cleaning solvents, and other contaminants. Used in protective coatings. However, due to its potentially high toxicity, laws are in place around the world to limit or prohibit its use. Alternative coatings have been developed and commercialized. In particular, short-chain C6 fluorochemical coatings approach performance of conventional C8-based FC coatings without the high environmental risks.

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

Hexamethyldisiloxane (HMDSO) is a non-toxic material and produces no harmful materials during processing, making it an industrial choice as a replacement for C6 fluorocarbons. 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 show promising mechanical properties such as low internal stress, good adhesion, and excellent hydrophobic barrier performance. Although the water resistance offered by pp-HMDSO coatings is promising, pp-HMDSO coatings do not provide oleophobicity.

As the technological development of thin film technology progresses, chemical vapor phase studies have been conducted to create thin films of permanent hydrophobic and oleophobic functional groups using ultrashort-chain PFASs that exhibit unique functional properties for filtration applications. Developing growth processes continues to be required. The lack of suitable volatile precursors and the difficulty in controlling the composition of the coating are major obstacles to the realization of this goal.

<p>It is therefore an object of the present invention to produce robust and reliable fabrics, fabrics with hydrophobic and oleophobic properties for sanitary and filtration applications such as water separation, acoustics, medical, healthcare, food, etc. , as well as an apparatus for producing polymer fabrics.</p>

<p>According to the invention, this object is on the one hand to produce a polymer fabric having the features of claim 1, a method for producing a polymer fabric having the features of claim 9 and a polymer fabric having the features of claim 14. achieved by a device for</p><p>Preferred embodiments of the invention are described in the respective dependent claims.</p><p>The polymer fabric according to the present invention comprises a hydrophobic and oleophobic outer functional layer made from a first compound and a hydrophobic second functional layer made from a second compound, The first compound and the second compound are different from each other. Furthermore, the outer functional layer at least partially covers the second functional layer.</p><p>Further, the method according to the present invention for producing a polymer fabric is such that an outer functional layer providing hydrophobicity and oleophobicity is deposited on the polymer fabric by low pressure plasma coating technique and a second functional layer providing hydrophobicity is deposited on the polymer fabric by a low-pressure plasma coating technique, characterized in that the outer functional layer and the second functional layer are different from each other. Additionally, a second functional layer is deposited on the polymeric fabric before the outer functional layer is deposited on the polymeric fabric, the outer functional layer at least partially covering the second layer.</p><p>The basic idea of the present invention is to depart from the current system of providing the fabric with a layer having all the required characteristics or properties. According to the invention, two layers are provided on top of each other, the layers being different from each other. This allows the selection of different layers with different characteristics. Therefore, 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>Preferably, the second functional layer does not have oleophobic properties. This makes the second functional layer distinct from the outer functional layer, which provides hydrophobicity and oleophobicity. However, due to the superimposition of these two layers on top of each other, for example, the hydrophobicity of the outer layer does not need to be at a very high level, since a second functional layer is provided underneath which also provides the hydrophobicity.</p><p>In embodiments, the outer functional layer is a perfluoroalkyl- and polyfluoroalkyl-substance (PFAS)-based, and/or a perfluoropolyether compound (PFPE)-based plasma catalyst containing only 1, 2, or 3 carbon atoms. Nano coating. Furthermore, in another or combined embodiment, the second functional layer is a hexamethyldisiloxane (HMDSO) or diamond-like carbon (DLC) layer-based plasma nanocoating.</p><p>As mentioned above, the use of short-chain C6 fluorocarbon (FC) compounds is problematic and no longer accepted in some areas. Direct steps to replace C6 fluorocarbon (FC) compounds with ultrashort-chain C3-C1 fluorocarbons (FCs) such as perfluoroalkyl and polyfluoroalkyl substances (PFAS) appear to be a seemingly promising solution. Seem. However, although these compounds in principle provide hydrophobic and oleophobic properties, it has been found that depositing these compounds on fabrics using plasma nanocoating presents problems. During the process of plasma polymer coating, the thickness of the PFAS-based C3-C1 fluorocarbon (FC) layer is much thinner compared to the previous C6-C8-based fluorocarbon (FC) layer. Layers provided in particular on fabrics, for example woven fabrics, are therefore poorly layered and thus do not provide demonstrable hydrophobicity. Surprisingly, it has been found that even thin layers provide good oleophobicity.</p><p>This was also observed when analyzing layers produced by a perfluoropolyether compound (PFPE)-based plasma polymer coating process. However, the advantage of perfluoropolyether compounds over plasma nanocoatings based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) containing only 1, 2 or 3 carbon atoms is the perfluoropolyether compounds (PFPE ) is even more environmentally friendly.</p><p>According to the invention, the outer functional layer is based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) containing only 1, 2 or 3 carbon atoms and/or perfluoropolyether compounds (PFPE). It is a plasma nano-coating and is applied on a hydrophobic second functional layer. Therefore, the unproven hydrophobicity of the outer functional layer can be improved by the second functional layer of the invention. In other words, first a layer with good hydrophobicity is deposited on the fabric, then in a second further step the outer functional layer with hydrophobicity and oleophobicity is already covered by the second functional layer. deposited on the fabric. This configuration provides the fabric with excellent hydrophobic and oleophobic properties.</p><p>The second functional layer may be based on hexamethyldisiloxane (HMDSO) or diamond-like carbon (DLC) layers. Using plasma polymer coating, the second functional layer is thereby coated with a pp-HMDSO-based coating, i.e., a poly(dimethylsiloxane)-like (PDMS-like) coating, a fluorine-doped pp-HMDSO coating, and/or It can be formed as a fluorine-doped DLC coating. These coatings have sufficiently good deposition rates when deposited by plasma polymer techniques to produce layers thicker than the outer functional layers described above. Therefore, the combination of these two layer technologies allows polymer plasma coating to provide excellent hydrophobic and oleophobic properties to polymer fabrics.</p><p>The outer functional layer and/or the second functional layer are preferably deposited by a low pressure plasma coating technique. This technique is also known as plasma-enhanced chemical vapor deposition (PECVD). This technique uses a cold plasma. Therefore, this technique is suitable for temperature-sensitive polymeric materials such as monofilament meshes, composite membranes, and the like. PECVD can be used to deposit a highly crosslinked polymer network with functional groups incorporated into the network, resulting in high long-term stability of the modified surface.</p><p>Generally, the polymeric fabric can be any type of fabric. In one embodiment, the polymeric fabric comprises a woven carrier layer that is woven from first monofilament yarns and second monofilament yarns, the first monofilament yarns and second monofilament yarns being manufactured from the same or different polymeric materials. be done. The monofilament yarns provided are particularly suitable for the proposed plasma-based deposition process.</p><p>To improve the filtering properties of the polymeric fabric, the polymeric fabric can comprise a composite membrane comprising 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 may be spun directly onto the woven carrier layer or spun onto a substrate and later transferred to the woven carrier layer during the bonding process.</p><p>As explained, the thickness of the outer functional layer is smaller than that of the second functional layer. Good hydrophobicity and oleophobicity can be achieved 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. For example, the second functional layer can have a layer thickness of 20-300 nm and the outer functional layer preferably has a layer thickness of 10-150 nm.</p><p>According to the method of the present invention for producing a polymer fabric, an outer functional layer providing hydrophobicity and oleophobicity is deposited on the polymer fabric by low pressure plasma coating technique and a second functional layer providing hydrophobicity. is deposited on the polymer fabric by a low pressure plasma coating technique, the outer functional layer and the second functional layer being different from each other. Additionally, a second functional layer is deposited on the polymeric fabric before the outer functional layer is deposited on the polymeric fabric, the outer functional layer at least partially covering the second functional layer.</p><p>The central idea of the invention is to provide two different layers, one at least partially overlapping the other. This allows features of the outer functional layer to be supported by features of the second functional layer. Thus, it is possible to achieve excellent results, namely in terms of imparting hydrophobicity and oleophobicity to polymeric fabrics, requiring the use of only one compound having all the necessary characteristics. This means that the outer functional layer contains only 1, 2 or 3 carbon atoms, which are more environmentally friendly than previously used compounds, but are comparatively less hydrophobic and oleophobic. This is particularly the case if it is based on perfluoroalkyl and polyfluoroalkyl substances (PFAS) and/or perfluoropolyether compounds (PFPE).</p><p>Non-polymerizing gases such as argon, helium, nitrogen, oxygen, and tetrafluoromethane gas, and/or prior to deposition of the second functional layer to improve adhesion with the second functional layer. These gas mixtures can be used to pretreat polymer fabrics by low pressure plasma techniques.</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 using gravure and/or slot die coating methods, The polymer fabric is coated with a UV-curable imprint resin and in a second step surface patterning is performed using UV imprint and/or hot embossing methods.</p><p>Finally, in addition to or alternatively to the pretreatments described above, prior to deposition of the second functional layer, the polymer fabric can be pretreated, wherein the polymer fabric is treated with an aqueous solution comprising sodium hydroxide (NaOH). processed by</p><p>The pre-treatment makes it possible to chemically and/or morphologically modify the surface of the fabric prior to the deposition of the functional layer, so that during the plasma polymerisation the plasma polymer adheres particularly well to the substrate. can be pasted. Furthermore, surface structuring to improve the roll-off effect, the so-called lotus effect, can also be achieved by nanoimprinting and plasma pretreatment. One of the pre-treatments or a combination of pre-treatments may provide cleaning, activation and/or texturing of the polymeric fabric, thus improving the adhesion of the second functional layer. According to the present invention, pretreatment or washing of the fabric is not considered as creating a layer on the fabric.</p><p>According to an improved embodiment, the outer functional layer and/or the second functional layer are deposited in one process and in one treatment step to form a fluorine-doped HMDSO plasma nano-coating and/or a fluorine-doped DLC plasma nano-coating. Get a nano-coating.</p><p>Polymeric fabrics with improved water resistance and oil repellency and/or a contact angle with water, diiodomethane and pentanediol of 110° to 150° and an oil grade of 5 to 8 according to AATCC118, according to the present invention can be provided.</p><p>The apparatus of the present invention for producing the polymer fabric of the present invention comprises a low pressure plasma coating device, the low pressure plasma coating device coating an outer functional layer providing hydrophobicity and oleophobicity with a low pressure plasma coating. a second functional layer configured to be deposited on the polymeric fabric by a low pressure plasma coating technique to provide hydrophobicity, the outer functional layer and the second functional layer configured to be deposited on the polymeric fabric by a low pressure plasma coating technique; are different from each other, the low pressure plasma coating device is configured to first deposit a second functional layer on the polymer fabric and then deposit an outer functional layer on the polymer fabric, the outer functional layer being deposited on the second at least partially covers the functional layer of</p><p>In the following, the invention will be further explained by means of preferred exemplary embodiments which are schematically shown in the accompanying drawings.</p>

<figref num="1">1 is a schematic diagram of a polymer fabric; FIG.</figref><figref num="2">1 is a schematic cross-sectional view of a polymer fabric according to the invention, including a membrane ("single layer"); FIG.</figref><figref num="3">1 is a schematic cross-sectional view of a composite material according to the invention in a so-called "sandwich" arrangement; FIG.</figref><figref num="4">1 is a schematic cross-sectional view of a composite material according to the invention having a multilayer structure ("multilayer"); FIG.</figref><figref num="5">1 is a schematic cross-sectional view of a composite material according to the invention in a "hybrid" configuration with two different carrier layers; FIG.</figref><figref num="6">BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of a method of making a polymer fabric of the invention;</figref>

FIG. 1 is a highly schematic illustration of a polymer fabric 100. FIG. On the left side of the figure, the polymer fabric 100 is provided with only an outer functional layer 120, on the right side, in addition to the outer functional layer 120, a second functional layer 110 is provided. In the following, the concept of the invention is further explained based on this example.

A greatly enlarged schematic view of a polymeric fabric 100 is shown in FIG. 1, 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 yarn due to the suboptimal deposition rate of this compound. This is particularly 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, before applying the outer functional layer 120, a second functional layer 110, for example based on HMDSO, is provided so that the fabric 100 is completely covered by the second functional layer 110. guaranteed to be 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, that area is covered by at least the second functional layer 110. FIG. Instead of the HMDSO second functional layer 110, this layer may be based on F-doped HMDSO, DLC, F-doped DLC, or a combination thereof.

FIG. 2 is a cross-sectional view of a polymer fabric as composite material 10 including a carrier layer 11. FIG. A membrane 12 formed by electrospinning is placed on the carrier layer 11 and adhered. In order 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 welded or glued joint location in the form of a point or a line. The small layer thicknesses of carrier material 11 and membrane 12 allow the connection points 13 to penetrate completely through the composite material at the connection location.

The composite material 10, and more particularly the electrospun membrane 12, can be perforated. The surface and pore fibers of the composite 10 can be coated with a coating applied by the two-step plasma coating method of the present invention described with reference to FIG. Hereby a first plasma coating of pp-HMDSO or DLC is applied to provide hydrophobicity only. A further plasma coating is then applied that provides a PFAS-based and/or PFPE-based layer containing only 1, 2 or 3 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 that provides hydrophobicity and oleophobicity. Optionally, F-doped HMDSO or F-doped DLC may be used as the second functional layer.

The surface coating of the fibers is indicated generally and schematically in the drawing by the indicated dots and lines 14 . The coating can also cover the fibers in the regions within the pores of the membrane 12 located inside or deep within the composite 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 fibers, depressions and irregularities, where the single fibers are individually wrapped or surrounded. be

Figure 3 shows a further composite material 10 in a so-called "sandwich" arrangement. Here the membrane 12 is arranged between two carrier layers 11, which protects the membrane 12 especially against mechanical stresses between the layers. In a sandwich configuration embodiment, for example 15.6 l/m at 200 Pa²s breathability can be reached. Basically up to 80l/m at 200Pa with sandwich, multi-layer or hybrid arrangements²s breathability can also be reached.

In all possible arrangements of the layers of composite material 10, these layers can be placed on top of each other by simple lamination. However, the layers may also be firmly connected to each other by connection points 13, which makes it possible to obtain a particularly reliable mechanical strength of the composite material 10. FIG.

FIG. 4 shows a multilayer arrangement (multilayer) of composite material 10 . In this arrangement, carrier layers 11 and membrane layers 12 are provided alternately on top of each other and supported. According to FIG. 4, two carrier layers 11 and two membrane layers 12 are provided. A multilayer arrangement may have any number of carrier layers 11 and/or membrane layers 12 . If desired, two membrane layers 12 may be provided directly over each other between two or more carrier layers. Even in the case of multilayer arrangements, 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 each other. Thus, the two-step plasma coating of the present invention can be applied to the inner surface of composite material 10, even in multi-layer structures.

FIG. 5 shows a variant of composite material 10 in which membrane 12 is arranged between first carrier layer 11 and second carrier layer 15 . Basically, the first carrier layer 11 can be designed in particular as a textile, and the second carrier layer 15, unlike the first carrier layer 11, 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, thereby advantageously providing filtering, protection and sound transmission properties in the composite material 10 . The two-step plasma coating of the present invention can also be applied to composite material 10 in the hybrid arrangement shown in FIG. , may be performed in deeper layers, such as in the opening of a pore.

The schematic diagram of FIG. 6 shows an example of a manufacturing process for a polymer fabric of the invention, such as a composite material comprising a carrier layer. A collection substrate (top view) is provided on which the electrospun membrane is formed (first manufacturing step). Electrospun membranes are formed according to generally known concepts and are further described below.

In a second step, the formed membrane is transferred and bonded to the carrier layer (bonding 1) and the original collection substrate on which the electrospun membrane was formed can optionally be removed (collection substrate removal ). According to the illustrations above, the carrier layer may 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 calendering process. Thus, the membrane can optionally be placed between two equal or different layers forming a sandwich structure. A second outer layer may be provided, for example as a mesh, lining or non-woven material. Finally, the two-step plasma coating of the present invention is applied to at least one carrier layer and membrane. This deposits a first layer that provides only hydrophobicity and a subsequent layer that provides both hydrophobicity and oleophobicity. The first layer may be a pp-HMDSO, fluorine-doped HMDSO, DLC, or fluorine-doped DLC layer. Further outer layers may be PFAS- and/or PFPE-based layers containing only 1, 2 or 3 carbon atoms.

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

Briefly, in the electrospinning process, high voltage is used to jet or melt a charged polymer solution from a pipette. Prior to reaching the collection screen, the jetted solution evaporates or solidifies and is collected as a web of interconnected fine fibers. One electrode is placed in the spinning solution/melt and the other electrode is attached to the collector. In many cases the collector is simply grounded. An electric field is applied to the end of the capillary containing the solution held 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 induce forces that oppose surface tension. As the electric field strength increases, the hemisphere of the fluid at the tip of the capillary elongates, forming a conical shape called a Taylor cone. As the electric field is further increased, the electrostatic repulsion reaches a critical value that overcomes the surface tension and charged fluid is ejected from the tip of the Taylor cone. The jetted polymer solution goes through an instability and stretching process and becomes very long and thin. The solvent then evaporates, leaving behind charged polymer fibers. In the case of melts, the jetted melt solidifies as it travels through the air.

Joining Methods Various joining techniques can be used. There are hot melt gravure lamination technology, ultrasonic bonding technology, dip bonding technology, UFD fiberization spray technology (hot melt), and spun web bonding technology.

Hot melt gravure lamination technology is industrially established for in-line processing. Thus, for "sandwich" type membranes, it is also possible to perform two-step bonding in one line. This technology is a multi-purpose hot melt lamination and coating system consisting of a gravure roller for dot coating, a revolver dosing head (positive/positive or negative/negative) and application rollers and lamination rollers and counter pressure rollers to use.

Two different reactive PU-based adhesives (one for the PU electrospun film and the other for the PA6 film) can be used by dot coating the adhesive using a gravure roller. A high joint strength can be obtained with an air permeability loss of about 15-25%. Adhesives must be chosen carefully (with respect to compatibility, physical and chemical compatibility, medical and food grade, etc.) so that no problems arise during final application of the membrane. Curing of the material by the adhesive is observed.

Immersion bonding techniques (chemical bonding) can be used for pretreatment of the support prior to the electrospinning process and may be preferred. Also, as a significant advantage, an additional process step for bonding can be eliminated. The two-layer laminate can then be used in a second bond, such as 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 adhesive filament strands. Heated air is used to stretch the strands and arrange them in regular or irregular patterns. In many cases, UFD technology can reduce adhesive usage by 20-50% without adversely affecting bond strength or durability due to precision application of the adhesive. A non-contact mode can be used, which makes damage to the electrospun fibers less likely during lamination. UFD technology is a cleaner process than hot melt gravure lamination.

The spun-web bonding technique yields a three-dimensional structure rather than a surface-enclosed membrane. Laminates obtained with an open structure are more flexible and breathable. Webs are made from a variety of materials such as copolyamides, copolyesters, copolyolefins, and polyurethanes. Spun web technology 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 cloth, mesh, and laminated vents to obtain smoother, thinner materials. This causes the material to pass between or under rollers of high temperature and pressure. The calendering conditions can affect the size and shape of the holes.

Plasma treatment of textile materials can be applied as a textile finishing process to improve surface properties such as water and oil repellency of plasma PECVD industrial and medical textiles and composites. Compared to conventional wet chemical fiber finishing, plasma technology has environmental advantages. The PECVD treatment can achieve, for example, improved adhesion, improved hydrophobicity, introduction of special functional groups to the surface, or modification of the surface morphology.

Plasma deposition, commonly known as plasma polymerization or PECVD, allows very thin polymer layers (nanoscale) to be deposited on substrate surfaces. This layer is formed by polymerization of an organic precursor gas that is polymerized directly onto the substrate surface. In contrast to conventional polymerization, plasma polymerization can use all monomer gases or vapors without being limited by their reactivity. Plasma polymers exhibit unconventional polymerization behavior due to branched and randomly terminated chains and a high degree of cross-linking.

The bulk structure of plasma polymers is completely disordered, in contrast to that of conventional polymers. Plasma polymer coatings (nano-thin films) have a high density of functional groups per volume, highly cross-linked branched plasma polymer networks, nanometer-thick coatings (&lt;200 nm), high adhesion of coatings to substrates, and It differs from conventional polymers by not changing the bulk properties of the substrate, which can be a polymeric fabric.

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

One mode of carrying out the invention is to first pretreat, preferably from about 2 minutes to about 5 minutes, at a base pressure of preferably from about 70 mTorr to about 200 mTorr, preferably from about 20°C up to about 60°C. °C, preferably at a power output of about 500 Watts to about 1800 Watts. The first coating step is then preferably applied for about 2 minutes to about 5 minutes at a base pressure of preferably about 15 mTorr to about 150 mTorr, preferably at a temperature of about 20°C up to about 60°C, preferably about 100°C. Do it with a power output of watts to about 1000 watts. A second coating step is then applied for preferably about 2 minutes to about 5 minutes at a base pressure of preferably about 15 mTorr to about 150 mTorr, preferably at a temperature of about 20°C up to about 60°C, preferably about 100°C. Run at a power output of watts to about 800 watts to deposit the outer functional layer. In this embodiment, the outer functional layer is based on C1-C3 based PFAS and the second functional layer is based on HMDSO or DLC.

<p>A preferred embodiment of the fabric-based filtration media according to the present invention comprises a woven structure with different patterns for maximum liquid repellency and thus has a contact angle of greater than 110°, as seen in Table 1. Superhydrophobic and oleophobic surfaces can be obtained. The degree of plasma-induced hydrophobicity and oleophobicity is also related to fabric structure and organization. Penetration of the plasma species into the fabric structure allows for higher liquid repellency. The hydrophobicity and oleophobicity of the substrate are therefore also determined by the arrangement of both the weft and warp filaments of the fabric, the final filament fineness, the fabric density and weave structure and the fiber content.</p><p><tables><img file="JP2023070108A_D0001.tif" /></tables></p>

<p>The oil repellency of the treated polymeric fabrics was also evaluated in parallel by AATCC 118, which is also a "pass/fail" type method that tests oil repellency rather than aqueous liquids. AATCC118 uses eight surface tension-lowering liquid hydrocarbons 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 n-heptane with a surface tension of 19.8 mN/m at 25°C. Up to 8 (highest oil repellency). A number attached to an oil that does not wet the sample is considered an oil repellency grade.</p><p><tables><img file="JP2023070108A_D0002.tif" /></tables> As can be seen from Table 2, similar and better results can be obtained using the coating of the present invention compared to the C6-based standard coating. This finding can be explained as follows. That is, physical modification improves the roll-off effect. A PDMS-like coating (ie, pp-HMDSO) is enhanced to obtain good water repellency, and a fluorinated top coating is effective against oils, fats, 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 have stability and resistance to accelerated aging treatment according to ASTM F1980-16. In addition, the two-step hydrophobic and oleophobic nano-coating of the filtration media has excellent water and oil repellency according to ISO4920 and AATCC118 respectively.</p><p>Based on the present invention, strong and reliable fabrics with hydrophobic and oleophobic properties can be provided.</p>