Method for coating a textile substrate by means of plasma

Abstract

This invention relates to a hollow cathode plasma polymerization method for use on fabric substrates, particularly a method for applying a fluoropolymer coating, especially a waterproof and / or oil-resistant coating, to fabric substrates, and products that can be obtained by such methods and systems.

Description

Technical Field

[0001] This invention relates to a method for applying a fluoropolymer surface coating to a fabric substrate. These fluoropolymer coatings can provide fabric substrates with water and / or oil repellency and, preferably, durable, resistance properties. These fabric substrates can, in particular, be temperature-sensitive.

[0002] As used herein, the term "one or more fabrics" includes both non-woven materials and woven or knitted textiles that can be made into articles for applications such as everyday use, industrial environments, personal protective equipment (PPE), sports, and leisure environments, such as clothing items. Other articles that can be made from fabrics are goods such as backpacks, umbrellas, tents, blinds, screens, canopies, tapestries, home textiles, sleeping bags, etc. Fabrics are also used as filter media articles, for example, for heating, ventilation, or air conditioning (HVAC) systems or for exhaust filters, diesel filters, liquid filters, filter media for medical applications, etc. Often, in HVAC applications, fabrics are not woven, knitted, or otherwise shaped into materials having a regular fibrous structure or regular fiber arrangement. The methods and processes of the present invention are applicable to all such fabrics.

[0003] To protect the fabric substrate, it is known to coat the fabric substrate with a coating, such as a fluoropolymer coating, to provide water and / or oil resistance.

[0004] WO 2014056968 A1 discloses a low-pressure plasma polymerization method for applying a fluorinated polymer nanocoating to a fabric substrate. This plasma polymerization method generates plasma in an entire vacuum chamber comprising multiple specially arranged electrode layers, and is therefore slow and difficult to combine with other surface treatments and / or in a continuous process. The use of polymer precursors is also wasteful due to the generation of large-volume plasma, which is particularly problematic considering the environmental issues associated with fluorinated compounds.

[0005] Therefore, there is a need in the art to provide a method for coating fabric substrates with fluoropolymers, which is efficient and can be combined and / or integrated with other surface treatments in a continuous process. Summary of the Invention

[0006] The object of this invention is to provide a solution to the following problem: to provide fluoropolymer coatings for fabric substrates, which have sufficient water and / or oil resistance.

[0007] Another object of the present invention is to provide a fast and efficient method that completes the coating process in a very short time and uses a limited amount of polymer precursor.

[0008] The present invention solves the above-mentioned technical problems by providing a method for depositing a fluorinated polymer coating on a fabric substrate using a fluorinated monomer via a low-pressure hollow cathode plasma polymerization process.

[0009] The low-pressure hollow cathode plasma polymerization method of the present invention is particularly efficient because it provides plasma directly in a limited space above the fabric substrate, thereby limiting the amount of precursor used, and can also do so without heating the fabric substrate to the point where it needs to be cooled. Attached Figure Description

[0010] These and further aspects of the invention will be explained in more detail by way of example and with reference to the accompanying drawings, in which:

[0011] Figure 1 A schematic cross-section of a hollow cathode type plasma source for use in this invention is shown, the plasma source comprising a pair of electrodes.

[0012] Figure 2 A cross-section of a roller-to-roll coating apparatus used for carrying out the method of the present invention is shown.

[0013] These figures are not drawn to scale. Detailed Implementation

[0014] This invention relates to a method for producing a fluoropolymer coating on a fabric substrate, the method comprising the following stages:

[0015] a. Provide fabric substrates;

[0016] b. Provide a first plasma source of the linear hollow cathode type, the first plasma source including at least a pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for depositing the fluorinated polymer coating on the fabric substrate;

[0017] c. Inject the first plasma generating gas into the electrodes of the first plasma source at a flow rate between 500 and 2500 sccm per meter of the first plasma source;

[0018] d. Apply a first power to the first plasma source such that the first power density of the plasma is between 0.5 kW and 15 kW per meter of the first plasma source;

[0019] e. With an inert carrier gas at a plasma flow rate of 0 to 1000 sccm per meter of the first plasma source, a fluorinated monomer is injected at a plasma flow rate between 20 and 1000 sccm per meter of the first plasma source, the fluorinated monomer being injected into the plasma between the electrodes of at least each electrode pair of the first plasma source.

[0020] f. A fluorinated polymer coating is deposited on the surface of the fabric substrate by exposing it to plasma from the first plasma source.

[0021] The first plasma source deposits a fluorinated polymer coating onto the fabric substrate.

[0022] The inventors have discovered that, by using this method, a fluorinated coating can be obtained on a variety of fabric substrates. The resulting substrates exhibit high water and / or oil resistance.

[0023] "Hollow cathode type plasma source" is used to mean a plasma source or ion source comprising one or more electrodes configured to generate a hollow cathode discharge. An example of a hollow cathode plasma source is described in U.S. Patent No. 8,652,586 (Maschwitz), which is incorporated herein by reference in its entirety. Figure 1 A hollow cathode type plasma source suitable for use in this invention is shown. The first and second plasma sources each comprise at least one pair of hollow cathode electrodes (1a) and (1b) arranged in parallel and connected via an AC power supply (not shown). An electrically insulating material (9) is arranged around the hollow cathode electrodes. Plasma generating gas is supplied via inlets (5a) and (5b). In use, precursor gas is supplied via a precursor gas inlet (6) and guided through a precursor injection slit (8) in the dark zone between the manifold (7) and the electrodes, into the plasma curtain 3. The AC power supply supplies a variable or alternating bipolar voltage to both electrodes. The AC power supply initially drives the first electrode to a negative voltage, thereby allowing plasma formation, while the second electrode is driven to a positive voltage to serve as the anode of the voltage application circuit. The AC power supply then drives the first electrode to a positive voltage, reversing the roles of cathode and anode. As one of these electrodes is driven to a negative (1a), a discharge (2a) forms within the corresponding cavity. The other electrode then forms the anode, causing electrons to bypass the plasma through an outlet (10) and travel to the anode side, thus completing the circuit. Therefore, a curtain-shaped plasma (3) is formed in the region between the first and second electrodes above the fabric substrate (4). The substrate (4) is currently shown as a monolithic substrate; however, it can also be a strip, for example, in a roll-to-roll coating apparatus. This method of driving a hollow cathode with AC electricity helps to form a uniform linear plasma that spans the fabric substrate perpendicular to the direction of travel of the fabric substrate (11). For the purposes of this patent, the electron emission surface may also be referred to as the plasma generating surface.

[0024] The linear hollow cathode type plasma source of the present invention provides linear plasma and is arranged perpendicular to the travel direction of the fabric substrate. Typically, compared to point sources or nozzle sources, these plasma sources vertically span the width of the fabric substrate, providing a linear plasma curtain across the entire width of the fabric substrate. Clearly, a substrate carrier supporting an array of substrates can be used instead of a single substrate.

[0025] "Closed-loop electron drift" refers to the electron current induced by intersecting electric and magnetic fields. In many conventional plasma generation devices, closed-loop electron drift forms a closed circulation path or a "racetrack" for the electron flow.

[0026] "AC power" refers to electricity from an alternating current source, where the voltage varies at a certain frequency in the form of a sine wave, square wave, pulse, or some other waveform. The voltage change is often from negative to positive (i.e., relative to ground). In bipolar form, the power output delivered by the two wires is typically about 180° out of phase.

[0027] An "electrode" provides free electrons during plasma generation, for example, when the electrode is connected to a power supply that provides voltage. The electron-emitting surfaces of a hollow cathode are considered together as an electrode. Electrodes can be made of materials well known to those skilled in the art, such as steel, stainless steel, copper, or aluminum. However, these materials must be carefully selected for each plasma enhancement method, as different gases during operation may require different electrode materials to excite and sustain the plasma. The performance and / or durability of the electrodes can also be improved by providing a coating.

[0028] For any plasma source of the present invention, the power density of the plasma is defined as the power dissipated in the plasma generated at the electrodes according to the size of the plasma. In a linear hollow cathode type plasma source, the "power density of the plasma" can be defined as the total power applied to the source divided by the total length of the plasma.

[0029] "Plasma in meters," also referred to herein as "total plasma length," is defined as the distance between the ends of plasma generated by a pair of electrodes in a direction transverse to the direction of travel of the fabric substrate to be coated. When the plasma source comprises more than one pair of electrodes, the total plasma length is defined as the sum of the distances between the ends of plasma generated by each pair of electrodes in a direction transverse to the direction of travel of the fabric substrate to be coated. As will be well understood by any person skilled in the art, these linear hollow cathode sources are scalable because their length can be adjusted to span the width of the substrate to be treated. The length of the plasma source can, for example, be several meters. Therefore, it is meaningful to express the flux and applied power in units that depend on the total length of the plasma source, because, for example, doubling the length of the plasma source would obviously require doubling the applied power and flux.

[0030] As used herein, the following terms have the following meanings: unless the context clearly indicates otherwise, "a / an" and "the" as used herein refer to both the singular and plural indicators. For example, "a room" means one room or more rooms.

[0031] As used herein, “comprise,” “comprising,” “comprises,” and “comprised of” are synonymous with “include,” “including,” “includes,” or “contain,” “containing,” and are inclusive or open-ended terms that specify the presence of, for example, a component and do not exclude or preclude the presence of any other unlisted components, features, elements, components, or steps known in the art or disclosed herein.

[0032] The range of values ​​listed by endpoints includes all numbers and fractions contained within that range, as well as the listed endpoints.

[0033] The present invention further relates to a method for producing a fluoropolymer coating on a fabric substrate, the method comprising the following stages:

[0034] a. Provide fabric substrates;

[0035] b. Provide a first plasma source of the linear hollow cathode type, the first plasma source including at least a pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for depositing the fluorinated polymer coating on the fabric substrate;

[0036] c. Inject the first plasma generating gas into the electrodes of the first plasma source at a flow rate between 500 and 2500 sccm per meter of the first plasma source;

[0037] d. Apply a first power to the first plasma source such that the first power density of the plasma is between 0.5 kW and 15 kW per meter of the first plasma source;

[0038] e. With an inert carrier gas at a plasma flow rate of 0 to 1000 sccm per meter of the first plasma source, a monomer is injected at a plasma flow rate between 20 and 1000 sccm per meter of the first plasma source, the precursor being injected into the plasma at least between the electrodes of each electrode pair of the first plasma source.

[0039] f. Provide a second plasma source of the linear hollow cathode type, the second plasma source including at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for surface activation of the substrate;

[0040] g. Inject the second plasma generating gas into the electrodes of the second plasma source at a flow rate between 500 and 4500 sccm per meter of the second plasma source;

[0041] h. Supply a second power to the second plasma source, such that the second power density of the plasma is between 0.5 kW and 15 kW per meter of the second plasma source, and

[0042] i. The surface of the fabric substrate is activated by exposing the fabric substrate to plasma from the second plasma source, and then the fluorinated polymer coating is deposited on the surface of the fabric substrate by exposing the fabric substrate to plasma from the second plasma source;

[0043] j. A fluorinated polymer coating is deposited on the surface of the fabric substrate by exposing it to plasma from the first plasma source.

[0044] A second plasma source activates the surface of the fabric substrate, and thereafter, a first plasma source deposits a fluorinated polymer coating onto the fabric substrate.

[0045] The inventors have discovered that by using this method, fluoropolymer coatings can be obtained on a variety of substrates. The resulting substrates exhibit high water and / or oil resistance.

[0046] In some embodiments of the invention, for depositing a fluorinated polymer coating, the first plasma generating gas / monomer molar ratio can be up to 70, advantageously, the first plasma generating gas / monomer molar ratio is at least 1, particularly including between 1 and 50, particularly including between 1 and 30; particularly including between 1.5 and 30, particularly including between 1.5 and 20.

[0047] For surface activation, in some embodiments of the invention, the fabric substrate may be contacted with plasma for a period of time, which is advantageously included between 4 and 10 s, advantageously between 5 and 10 s, and advantageously between 6 and 8 s.

[0048] The surface activation and fluoropolymer coating deposition of the method of the present invention are preferably carried out, for example, in a vacuum chamber at a pressure between 0.005 and 0.050 Torr, more preferably between 0.007 and 0.040 Torr, and even more preferably between 0.010 and 0.030 Torr. A suitable venting device is used to maintain the desired pressure during the method. Such venting devices are well known in the art.

[0049] The second and first plasma sources are preferably each connected to an AC or pulsed DC generator (the frequency of which is typically between 5 and 150 kHz, preferably between 5 and 100 kHz) or to a DC generator.

[0050] The second and / or first linear hollow cathode plasma sources used in this invention can operate in one or more vacuum chambers. For example, the second linear hollow cathode plasma source can operate in a second vacuum chamber, and the first linear hollow cathode plasma source can operate in a first vacuum chamber. These vacuum chambers can be equipped with sealed doors for batch processing of substrates. Preferably, these vacuum chambers are connected uninterruptedly to allow continuous movement between them. Furthermore, these vacuum chambers can be arranged such that different sources with different deposition forms or surface treatments can be adjacent to each other. In some cases, these sources that enable different deposition forms are flat or rotating cathodes for magnetron sputtering deposition. In particular, this vacuum chamber can be combined with a device for conveying flexible substrates along these sources in a roll-to-roll manner.

[0051] Batch processing is particularly suitable for handling three-dimensional shaped substrates. The three-dimensional substrate can be exposed to the plasma of the present invention by appropriate movement, such as rotation and / or displacement, in order to uniformly process the substrate surface.

[0052] According to certain embodiments of the invention, the second and / or first linear hollow cathode plasma source used in the invention may be constructed of a hollow cathode comprising, for example, one or more pairs of electrodes connected to an AC or pulsed DC generator, into which plasma-generating gas is injected, a discharge occurs, and the generated plasma exits from openings in the electrodes. Each electrode forms a linear cavity connected to a tube, which makes it possible to introduce plasma-generating gas, which will be ionized by the discharge, into the cavity. The plasma generated by the linear hollow cathode plasma source extends longitudinally across the width of the fabric substrate, or substantially in a direction perpendicular to the direction of travel of the fabric substrate.

[0053] The electrodes used in the hollow cathode type plasma source of the present invention may be provided with an inlet for supplying plasma generating gas and an outlet in the shape of, for example, a slit, a row of holes or nozzles or a column of holes or nozzles, for directing the generated plasma toward the fabric substrate.

[0054] According to certain embodiments of the invention, the distance between the outlets of the electrodes of the plasma source may be between 5 cm and 15 cm, preferably between 7 cm and 12 cm, and preferably between 8 cm and 10 cm. The inventors have found that at shorter distances, certain substrates, such as fabrics or polymer films, may be damaged, for example, by ion bombardment. Larger distances may result in reduced adhesion and decreased water and / or oil resistance.

[0055] For surface activation, in some embodiments of the invention, the second plasma generating gas is typically N2 or O2 or an O2 / N2 mixture. Alternatively, the second plasma generating gas can be N2O. Alternatively, the second plasma generating gas can include Ar or an Ar / O2 mixture or an Ar / N2 mixture. In a preferred embodiment, the second plasma generating gas comprises N2 alone or a mixture thereof with another gas, in which case higher water resistance is generally observed compared to the absence of N2. In another preferred embodiment, the second plasma generating gas is O2-free, for example, pure N2, thus limiting the risk of O2 interference in subsequent coating steps. The generator frequency is typically between 5 and 150 kHz, preferably between 5 and 100 kHz. In some advantageous embodiments, the second plasma generating gas is pure N2.

[0056] For the deposition of fluoropolymer coatings, the first plasma generating gas is advantageously Ar, He, or an Ar / He mixture. In some advantageous embodiments, the atomic ratio of He / Ar includes between 0.5 and 10, advantageously between 2 and 8, advantageously between 3 and 7, and advantageously between 3.5 and 5.5. At these ratios, the plasma temperature remains low while the plasma source lifetime is long.

[0057] The generator frequency is typically between 5 and 150 kHz, preferably between 5 and 100 kHz. Monomeric gas is uniformly injected along the first plasma source, at least between the electrodes of each electrode pair.

[0058] When the first plasma source includes more than one electrode pair, a monomer gas can be additionally injected between each electrode pair toward the plasma present between the outlets of the electrode pairs of the plasma source in the space between the fabric substrate and the plasma source. In each case, the total flow is uniformly distributed among all injection points.

[0059] The monomer gas is activated by plasma from a first plasma source. The fabric substrate is brought close to the source, and a thin fluorinated polymer coating is deposited on the fabric substrate by the activating gas.

[0060] The flow rate of the ionizable plasma-generating gas introduced into the electrode cavity can be controlled by a mass flow meter placed on a tube between the gas storage tank and the plasma source. The flow rate of the precursor gas injected into the plasma can also be controlled by a mass flow meter. The operating pressure range of the second and first plasma sources is typically between 5 and 50 mTorr. Pumping to maintain the vacuum is preferably provided by a turbomolecular pump connected to the vacuum chamber. Pumping can be provided on the same side of the fabric substrate as the plasma source or along its path of travel and adjacent to the plasma source. Alternatively, pumping can be provided on the opposite side. To achieve good deposition uniformity on the fabric substrate, the pumping is configured to pump uniformly across the width of the fabric substrate. The width of the fabric substrate is perpendicular to the direction of travel of the fabric substrate.

[0061] In embodiments of the invention, the formation of the fluorinated polymer coating comprises plasma polymerization of a monomeric precursor introduced into the plasma of a hollow cathode type plasma source, the monomer comprising fluorine. The precursor gas is preferably uniformly distributed and injected between the electrodes of each electrode pair, and optionally also injected between multiple electrode pairs when more than one electrode pair is used.

[0062] In embodiments of the present invention, the generation of the fluorinated polymer coating includes plasma polymerization of a fluorinated monomer precursor introduced into plasma from a hollow cathode type plasma source, the monomer having the general formula (I):

[0063] aC n F 2n+1 C m X 2m CR1Y-OCO-C(R2)CH2(I)

[0064] Where n is 2 to 6, m is 0 to 9, X and Y are H, F, CI, Br or I, R1 is H or alkyl or substituted alkyl, such as at least partially halogenated alkyl, and R2 is H or alkyl or substituted alkyl, such as at least partially halogenated alkyl.

[0065] Monomers having Formula I can be monomers containing six methyl groups. Suitably, monomers having Formula I are 1H,1H,2H,2H-perfluorooctyl acrylate. Suitably, monomers having Formula I are 1H,1H,2H,2H-perfluorooctyl methacrylate.

[0066] Preferably, the liquid monomer is delivered to the plasma source without using a carrier gas. However, in some embodiments, a different gas may be used as a carrier gas to introduce the fluorinated precursor monomer into the plasma chamber.

[0067] Preferably, the fluorinated monomer precursor is supplied as a liquid or solid monomer, which is then vaporized and transported to the plasma source in its vaporized form. Preferably, the vaporized monomer is transported to the plasma chamber without the use of a carrier gas. Alternatively, if desired, the fluorinated monomer supply system uses a carrier gas to transport the vaporized monomer precursor to the plasma chamber.

[0068] Preferably, when a carrier gas is used, the carrier gas is an inert gas, such as selected from He or Ar, and / or any mixture of these gases. In a preferred method, a single carrier gas is used. This is most preferably He or Ar, and even more preferably He.

[0069] Preferably, when using a carrier gas, the flow rate is between 100 and 1000 sccm per meter of plasma. Advantageously, the carrier gas flow rate is at least 200 sccm per meter of plasma source, more advantageously at least 300 sccm, and even more advantageously at least 300 sccm. Advantageously, the carrier gas flow rate is at most 900 sccm per meter of plasma source, more advantageously at most 800 sccm, and even more advantageously at most 700 sccm.

[0070] Preferably, when using a carrier gas, the amount of carrier gas is about 5% to about 1500% of the unit flow rate, preferably about 25% to about 1500%, more preferably 50% to 1300%, for example 75% to 1300% of another gas.

[0071] Any precursor gas can be gaseous at room temperature and pressure, or it can be a vaporized liquid or solid.

[0072] The monomer flow rate is between 20 and 1000 sccm (standard cubic centimeters per minute) per meter of plasma, preferably between 30 and 500 sccm per meter of plasma, or alternatively between 50 and 300 sccm per meter of plasma. This range is necessary to obtain high dynamic deposition rates, approximately 10 to 200 nm·m / min. Generally, higher fluorinated monomer flow rates require a higher electrical input to the plasma source. Standard cubic centimeters per minute (sccm) is a unit of flow rate measurement that indicates cubic centimeters per minute (cm³) under standard conditions of temperature and pressure for a given fluid. 3 / min). For the present invention, these standard conditions are fixed at a temperature of 0°C (273.15K) and a pressure of 1.01 bar.

[0073] In some embodiments of the invention, the ratio of the first plasma generating gas flow rate to the monomer flow rate is at least 1, advantageously between 1 and 40, more advantageously between 1 and 20, and even more advantageously between 1 and 20.

[0074] According to embodiments of the present invention, the temperature of the fabric substrate is between 20°C and 40°C. Using the method of the present invention, this temperature can be maintained during surface activation and deposition of the fluoropolymer coating without the presence of a cooling device in contact with the fabric substrate. The hollow cathode plasma source used is configured to subsequently coat and activate the fabric substrate via discharge. The substrate temperature can be controlled along with the applied power range and the type and flow rate of the plasma generating gas.

[0075] According to the present invention, the fabric substrate is essentially composed of fabric. However, this does not preclude the fabric substrate from being temporarily or permanently fixed to a suitable carrier material.

[0076] The fabric substrate can be selected from any of the following embodiments.

[0077] The fabric substrate can be selected from textiles based on one or more of the following fiber materials or fibers: synthetic fibers, such as polyester, polyethylene, polypropylene, or aramid; natural fibers, such as wool, cotton, silk, or linen. The fabric substrate can be a woven or nonwoven textile.

[0078] Generally, in this invention, the fabric substrate can include any textile, fabric material, fabric garment, felt, or other fabric structure. The term "fabric" can be used to mean textile, cloth, fabric material, fabric clothing, or another fabric product. The term "fabric structure" is intended to mean a structure having, for example, woven, nonwoven, knitted, tufted, crocheted, knotted, and / or compressed warp and weft yarns. The terms "warp" and "weft" refer to weaving terms that have their common meaning in the textile field, as used herein; for example, warp refers to the longitudinal or longitudinal yarn on a loom, while weft refers to the transverse or transverse yarn on a loom.

[0079] Furthermore, the fabric substrates that can be used in this invention may include fabric substrates having natural and / or synthetic fibers. It is worth noting that the term "fabric substrate" does not include materials commonly referred to as any type of paper (even if paper may include multiple types of natural and synthetic fibers or mixtures of two types of fibers). Moreover, fabric substrates include two textiles in the form of their filaments, woven material, or even fabric forms already made into finished articles (clothing, blankets, tablecloths, napkins, bedding, curtains, carpets, shoes, etc.). In some instances, the fabric substrate has a woven, knitted, nonwoven, or tufted fabric structure.

[0080] In embodiments of the invention, the fabric substrate can be a woven fabric in which warp and weft yarns are positioned at approximately 90° to each other. The woven fabric can include, but is not limited to, fabrics with a plain weave, fabrics with a twill weave (where the twill creates diagonals on the surface of the fabric), or fabrics with a satin weave. The fabric substrate can be a knitted fabric with a loop structure, including one or both of warp-knitted and weft-knitted fabrics. A weft-knitted fabric refers to a row of loops in the fabric formed by the same yarn. A warp-knitted fabric refers to a fabric structure in which each loop is formed by a separate yarn, introduced primarily in the warp direction. The fabric substrate can also be a nonwoven product, such as a flexible fabric comprising multiple fibers or filaments bonded together and / or interlocked together by chemical treatment methods (e.g., solvent treatment), mechanical treatment methods (e.g., embossing), heat treatment methods, or two or more combinations of these methods.

[0081] In embodiments of the invention, the fabric substrate may include one or both of natural and synthetic fibers. Natural fibers that may be used include, but are not limited to, wool, cotton, silk, linn, jute, flax, or hemp. Other fibers that may be used include, but are not limited to, rayon fibers or those thermoplastic aliphatic polymer fibers derived from renewable resources (including, but not limited to, corn starch, tapioca starch products, or sugarcane). These other fibers may be referred to as “natural” fibers. In some instances, the fibers used in the fabric substrate include combinations of two or more of the natural fibers listed above, combinations of any of the natural fibers listed above with another natural fiber or with a synthetic fiber, mixtures of two or more of the natural fibers listed above, or mixtures of any of them with another natural fiber or with a synthetic fiber.

[0082] In one embodiment of the invention, the synthetic fibers that can be used in the fabric substrate may include polymer fibers, such as, but not limited to, polyvinyl chloride (PVC) fibers, PVC-free fibers made of polyester, polyamides, polyimides, polyacrylic acid, polyacrylonitrile, polypropylene, polyethylene, polyurethane, polystyrene, and polyaramids (e.g., referred to as...). Para-aramids, such as those from DuPont (EIdu Pont de Nemours and Company), glass fibers, poly(propylene terephthalate), polycarbonate, polyester terephthalate, polyethylene, or polybutylene terephthalate. In some instances, the fibers used in the fabric substrate may include combinations of two or more fiber materials, combinations of synthetic fibers with another synthetic or natural fiber, mixtures of two or more synthetic fibers, or mixtures of synthetic fibers with another synthetic or natural fiber. In some instances, the fabric substrate is synthetic polyester fiber or a fabric made of synthetic polyester fiber.

[0083] In embodiments of the invention, the fabric substrate may comprise both natural and synthetic fibers. In some instances, the amount of synthetic fibers accounts for from about 20 wt% to about 90 wt% of the total fiber amount. In some other instances, the amount of natural fibers accounts for from about 10 wt% to about 80 wt% of the total fiber amount. In some other instances, the fabric substrate comprises natural and synthetic fibers in a woven structure, wherein the amount of natural fibers is about 10 wt% of the total fiber amount and the amount of synthetic fibers is about 90 wt% of the total fiber amount. In some instances, the fabric substrate may also comprise additives, such as, but not limited to, one or more of the following: colorants (e.g., pigments, dyes, colorants), antistatic agents, brighteners, nucleating agents, antioxidants, UV stabilizers, fillers, lubricants, and combinations thereof.

[0084] In one embodiment of the present invention, the fabric substrate is selected from synthetic fiber-based textiles.

[0085] Advantageously, the fabric substrate is selected from polyester-based substrates.

[0086] The fabric substrate can also be finished garments.

[0087] In some advantageous embodiments, the second and / or first plasma source of the hollow cathode type of the present invention has the following dimensions: a length between 250 mm and 4000 mm and a width between 100 and 800 mm, thereby providing a power between 0.5 kW and 15 kW per meter of plasma.

[0088] In each plasma source of the present invention, a power density is applied between the two electrodes of any electrode pair, such that the power density is between 0.5 and 15 kW per meter of plasma, preferably between 0.7 and 10 kW per meter of plasma. The power density is typically adjusted together with the fluorinated monomer flow rate. Below this power density of 0.5 kW per meter of plasma, the deposition rate is low and the coating adhesion is insufficient, while above 15 kW per meter of plasma, and indeed sometimes even above 10 kW per meter of plasma, the fluorinated monomer fragmentation is too high, and the resulting coating is not sufficiently waterproof.

[0089] Coatings are typically manufactured to a geometric thickness of at least 50 nm, or even at least 60 nm, or even at least 70 nm to make the fabric waterproof. Water resistance after washing is improved at thicknesses of at least 100 nm, or even at least 300 nm, or even at least 400 nm. Thicknesses can be up to 500 nm, or even 600 nm, or even 700 nm, or even 800 nm, or even 1000 nm or 1500 nm to limit processing time for rapid methods. In embodiments of the invention, the thickness can preferably be between 20 and 800 nm, particularly between 30 and 600 nm. The selected thickness depends on the desired technical effect on the fabric substrate so coated. For each fabric with different surface roughness and porosity, an optimal thickness needs to be adjusted. The coating thickness is determined by depositing the fluoropolymer coating onto a flat substrate such as a polymer film, metal sheet, or glass sheet under the same conditions.

[0090] The fabric substrate may have a thickness between 12 μm and 10 mm, preferably between 15 μm and 5 mm, and more preferably between 25 μm and 2 mm.

[0091] The present invention further relates to fabric substrates obtained by any one or more of the methods described above.

[0092] The invention further relates to a vacuum enclosure, such as a roll-to-roll vacuum coating enclosure, which includes a first and / or second hollow cathode type plasma source for carrying out the methods of the invention. In alternative examples, the vacuum enclosure may be a horizontal or vertical vacuum coating line.

[0093] Fabric substrates can be processed in a roll-to-roll manner, such as, for example, in Figure 2 As shown. In Figure 2In this process, the fabric substrate (29) is unwound from the unwinding roller (21) and rewinds onto the main roller (25) on roller (27) for the coating process of the present invention. The fabric substrate is then guided onto roller (28) to be wound onto rewinding roller (22). The coating process of the present invention is performed using a plasma source (23) that generates plasma (26) on the surface of the polymer substrate, thereby activating the fabric surface and / or polymerizing fluorinated monomers to form a fluorinated polymer coating on the fabric substrate. Figure 2 The arrows indicate the direction of movement of the fabric substrate. The direction of the film can be reversed to repeat the coating process, wherein the fabric substrate moves in the opposite direction to the previous movement. Additional surface treatment or coating equipment (24), such as additional plasma sources or magnetron sputtering sources, can be positioned around the plasma source (23). Within the scope of the invention, for example, one plasma source can be used for surface activation while another can be used to coat the fluoropolymer coating. Alternatively, the substrate surface can be activated first using one or two plasma sources, and then a fluoropolymer coating can be deposited on the fabric substrate using one or two plasma sources.

[0094] Roll-to-roll processes are suitable for substantially flat fabric substrates. Those skilled in the art will readily understand that roll-to-roll processes are not suitable for every type of fabric substrate. For example, certain fabric substrates that have been carefully manufactured into finished articles and are not suitable for roll-to-roll processing can be processed using the methods of this invention, for example, by conveyor belt-type processes or any other method that effectively exposes the substrate to plasma. Of course, flat fabric substrates can also be processed on a conveyor belt.

[0095] In an advantageous embodiment, the first and / or second hollow cathode type plasma source of the present invention for carrying out the method of the present invention is placed below the horizontally moving fabric substrate to be processed. The fabric surface can then be processed in an upward manner. Alternatively, the first and / or second hollow cathode type plasma source of the present invention for carrying out the method of the present invention is placed vertically near the vertically moving fabric substrate to be processed. The fabric surface can then be processed in a lateral manner. These arrangements reduce the risk of coating defects, for example, due to powder or coating machine debris falling onto the fabric surface.

[0096] In embodiments of the invention, an airlock is provided for introducing and removing a fabric substrate into a vacuum chamber, in which the method of the invention is performed. Within the airlock, the substrate is raised from atmospheric pressure to a process vacuum level and degassed if necessary.

[0097] For textiles and fabrics to be coated on rollers (2D), the fabric roll can be degassed to a degassing level of up to 6.7 Pa (50 mTorr), more preferably up to 5.3 Pa (40 mTorr), or even more preferably up to 3.3 Pa (25 mTorr). Alternatively, the fabric roll may be degassed in a vacuum chamber until the vacuum chamber comprises a degassing level of up to 13.3 Pa (100 mTorr), more preferably up to 6.7 Pa (50 mTorr), such as 5.3 Pa (40 mTorr) or less. Note that the degassing level of the vacuum chamber can depend on the load, i.e., on the fabric structure, polymer, thickness, and openness, and on the roll size of the fabric roll placed within the chamber.

[0098] To determine the degassing level of a finished fabric (3D) or fabric roll (2D), it is necessary to determine the pressure increment in the vacuum chamber due to the gas released from the textile. Furthermore, the article is placed in a vacuum chamber (e.g., a plasma chamber) that is evacuated to a degassing pressure P. 脱气 The degassing pressure is less than 26.7 Pa (200 mTorr), preferably less than 13.3 Pa (100 mTorr), and if less than 6.7 Pa (50 mTorr), and then the inlet and outlet of the vacuum chamber are sealed. After a preset time of 60 seconds, the pressure increment ΔP inside the chamber is measured. The degassing level of the textile is then calculated by subtracting the pressure increment ΔP from the degassing pressure P inside the vacuum chamber. 脱气 The whistling leakage pressure is given. Optionally, if more than one finished textile (3D) is placed in the vacuum chamber, the degassing level of one textile is given by subtracting the vacuum chamber's degassing pressure P from the pressure increment ΔP. 脱气 The audible leakage pressure is given by dividing the pressure by the number of substrates in the vacuum chamber. Therefore, the vacuum chamber at the degassing pressure P... 脱气 The audible leakage pressure is determined by repeating the same procedure on the empty chamber (from which all electronic substrates are removed) until the same degassing pressure P is reached. 脱气 All inlets and outlets of the sealed vacuum chamber are checked, and the pressure increment is measured after the same preset time (i.e., 60 seconds) as the loading chamber.

[0099] In a preferred embodiment, degassing and surface activation are combined in a single processing step.

[0100] In some embodiments of the present invention, the following items are involved:

[0101] Item 1. A method for producing a fluoropolymer coating on a fabric substrate, the method comprising the following stages:

[0102] a. Provide fabric substrates;

[0103] b. Provide a first plasma source of the linear hollow cathode type, the first plasma source including at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for depositing the waterproof coating on the fabric substrate;

[0104] c. Inject the first plasma generating gas into the electrodes of the first plasma source at a flow rate between 500 and 2500 sccm per meter of the first plasma source;

[0105] d. Apply a first electrical current to the first plasma source such that the first power density of the plasma is between 0.5 kW and 15 kW per meter of the first plasma source;

[0106] e. A fluorinated monomer is injected at a plasma flow rate between 20 and 1000 sccm per meter of the first plasma source, the monomer being injected into the plasma at least between the electrodes of each electrode pair of the first plasma source; with an inert carrier gas at a plasma flow rate between 0 and 1000 sccm per meter of the first plasma source; preferably, the flow rate of the fluorinated monomer is between 150 and 600 sccm per meter of the plasma, alternatively between 200 and 500 sccm.

[0107] f. A waterproof coating is deposited on the surface of the fabric substrate by exposing it to plasma from the first plasma source.

[0108] Item 2. The method according to Item 1 further includes the following stages:

[0109] a. A second plasma source of the linear hollow cathode type is provided, the second plasma source including at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for surface activation of the fabric substrate;

[0110] b. Inject the second plasma generating gas into the electrodes of the second plasma source at a flow rate between 500 and 4500 sccm per meter of the second plasma source;

[0111] c. Supply a second power to the second plasma source, such that the second power density of the plasma is between 0.5 kW and 15 kW per meter of the second plasma source.

[0112] d. The surface of the fabric substrate is activated by exposing the fabric substrate to plasma from the second plasma source, and then the waterproof coating is deposited on the surface of the fabric substrate by exposing the fabric substrate to plasma from the second plasma source.

[0113] Item 3. The method according to any of the preceding items, characterized in that the fluorinated monomer has the following formula:

[0114] aC n F 2n+1 C m X 2m CR1Y-OCO-C(R2)CH2

[0115] Wherein n is 2 to 6, m is 0 to 9, X and Y are H, F, CI, Br or I, R1 is H or alkyl or substituted alkyl, such as at least partially halogenated alkyl, and R2 is H or alkyl or substituted alkyl, such as at least partially halogenated alkyl, preferably the fluorinated monomer is 1H,1H,2H,2H-perfluorooctyl acrylate or 1H,1H,2H,2H-perfluorooctyl methacrylate.

[0116] Item 4. The method according to any of the preceding items further includes degassing the fabric substrate, preferably simultaneously with activating the surface of the fabric substrate.

[0117] Item 5. The method according to any of the preceding items, wherein the fabric substrate is a fabric on a roller processed in a roller-to-roll process.

[0118] Item 6. The method according to any of the preceding items, characterized in that the second plasma generating gas comprises N2, O2, or a mixture of O2 and N2 or N2O.

[0119] Item 7. The method according to any of the preceding items, characterized in that the first plasma generating gas comprises He, Ar, or a mixture of He and Ar.

[0120] Item 8. The method according to any of the preceding items, characterized in that the carrier gas comprises He, Ar, or a mixture of He and Ar.

[0121] Item 9. The method according to any of the preceding items, characterized in that the carrier gas flow rate is between 100 and 1000 sccm per meter of plasma, advantageously at least 200 sccm per meter of plasma source, more advantageously at least 300 sccm, and even more advantageously at least 300 sccm; advantageously, the carrier gas flow rate is at most 900 sccm per meter of plasma source, more advantageously at most 800 sccm, and even more advantageously at most 700 sccm.

[0122] Item 10. The method according to Item 7, characterized in that the second plasma generating gas comprises a mixture of He and Ar, wherein the atomic ratio He / Ar comprises between 0.5 and 10, advantageously between 2 and 8, advantageously between 3 and 7, and advantageously between 3.5 and 5.5.

[0123] Item 11. The method according to any one of items 2 to 8, characterized in that the fabric substrate is exposed to the plasma of the second plasma source for a period of time, said time being advantageously between 4 and 12 s, advantageously between 5 and 10 s, or advantageously between 6 and 8 s.

[0124] Item 12. The method according to any of the preceding items, characterized in that the ratio of the first plasma generating gas flow rate to the fluorinated monomer flow rate is at least 1, advantageously between 1 and 20.

[0125] Item 13. The method according to any of the preceding items, wherein the temperature of the fabric substrate is at most 40°C, advantageously during surface activation and deposition of the waterproof coating in the absence of a cooling device in contact with the fabric substrate.

[0126] Item 14. The method according to any of the preceding items, wherein the surface activation and waterproof coating deposition of the method are preferably carried out at a pressure between 0.005 and 0.050 Torr, preferably between 0.007 and 0.040 Torr, and more preferably between 0.010 and 0.030 Torr.

[0127] Item 15. The method according to any one of items 1 to 4 and 5 to 14, wherein the textile is a three-dimensional shaped finished textile, such as clothing or accessories, processed in a batch process.

[0128] It should be understood that although preferred embodiments and / or materials for providing embodiments according to the invention have been discussed, various modifications or changes can be made without departing from the scope and spirit of the invention. In particular, any possible embodiments discussed herein may be combined.

[0129] The invention will be more readily understood by referring to the following examples, which are included only to illustrate certain aspects and embodiments of the invention and are not intended to limit the invention.

[0130] Example

[0131] Water resistance was evaluated using spray rating according to standard ISO 4920 (2012). The water resistance was evaluated using the parameters in Table 1 after the initial coating and after several washing cycles according to ISO 6330 (2012). Oil resistance was tested according to ISO 14419.

[0132] Table 1

[0133]

[0134]

[0135] For the evaluation of water resistance, standard ISO 4920 (2012) was followed. Distilled or completely deionized water at (20±2)°C was used. Tests were conducted at ambient temperature, and samples were rated using a photographic spray rating scale.

[0136] Advantageously, the thickness can be evaluated on coated soda-lime glass substrates under the same conditions. On glass substrates, the thickness can be measured using a step profiler.

[0137] For the following examples, a hollow cathode type plasma source comprising a pair of electrodes is used. The plasma source is incorporated into a vacuum chamber. Flow rates expressed in sccm / m are flow rates measured in sccm per meter of plasma. The plasma generating gas is uniformly distributed in each electrode. When the plasma source comprises only a pair of electrodes, the fluorinated monomer and its carrier gas are uniformly distributed and injected between the electrodes of the electrode pair.

[0138] Scanning electron microscopy analysis of the substrate showed that, according to the embodiments of the present invention, there was no fiber damage, such as melting, etching, or burning.

[0139] The fabric substrate is 20×30cm 2 Fabric sheets are conveyed at a continuous speed on a glass carrier below the plasma source via a conveyor belt so that they come into contact with the plasma source.

[0140] The pressure in the vacuum chamber is maintained between 5 and 40 millitors.

[0141] Table 2 - Fabric Substrates

[0142] Material Woven or nonwoven thickness <![CDATA[Weight / m 2 > Polyester nonwoven 0.14-0.17mm <![CDATA[90-110g / m 2 ]]>

[0143] In the following example, surface activation is performed using a linear hollow cathode type second plasma source comprising two pairs of hollow cathode plasma generating electrodes connected to an AC, DC, or pulsed DC generator. The second plasma generating gas, N2, is injected into the electrodes of the second plasma source at a total flow rate of 2000 sccm per meter of plasma. The second power density is between 1 and 4.4 kW per meter of plasma. The fabric substrate moves through the plasma at a speed of approximately 2.5 m / min the required number of times to achieve the specified processing time.

[0144] In the following examples, the deposition of the waterproof coating is performed using a first plasma source of the linear hollow cathode type, which includes two pairs of hollow cathode plasma generating electrodes connected to an AC, DC, or pulsed DC generator.

[0145] Ar gas was used to generate the first plasma at a total flow rate of 1500 sccm per meter of the first plasma source.

[0146] The fluorinated monomer 1H,1H,2H,2H-perfluorooctyl acrylate (C6FA) is injected between the electrodes of the electrode pair of the first plasma source to deposit a fluorinated polymer coating on the surface of an activated fabric substrate. The fabric substrate is continuously moved through the plasma at a speed of approximately 2.5 m / min the required number of times to achieve the specified coating thickness. The thicknesses shown in the table below are those obtained on glass substrates under the same conditions, as it is unlikely that coating thickness can be reliably measured on most fabric substrates.

[0147] A coating thickness of 80 nm was obtained by using a monomer precursor flow rate of 70 sccm / m, a He carrier gas flow rate of 750 sccm / m for the monomer, and an argon plasma generating gas flow rate of 1500 sccm / m. As explained above, the flow rates are expressed as plasma per meter.

[0148] The resulting coating has a water resistance rating of at least 3.5. The oil resistance rating is initially 4.0 up to the fourth wash cycle. After 5 wash cycles, the oil resistance drops to 3.5, and after 6 wash cycles, the oil resistance drops to 3.0.

Claims

1. A method for producing a fluoropolymer coating on a fabric substrate, the method comprising the following stages: a. Provide at least one vacuum chamber; b. Providing a fabric substrate in the at least one vacuum chamber; c. Provide a first plasma source of the linear hollow cathode type, the first plasma source including at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for depositing a waterproof coating on the fabric substrate; d. Inject the first plasma generating gas into the electrodes of the first plasma source at a flow rate between 500 and 2500 sccm per meter of the first plasma source; e. Apply a first electrical current to the first plasma source such that the first power density of the plasma is between 0.5 kW and 15 kW per meter of the first plasma source; f. Injecting a fluorinated monomer at a flow rate between 20 and 1000 sccm per meter of the first plasma source, the monomer being injected into the plasma between the electrodes of at least each electrode pair of the first plasma source; with an inert carrier gas at a flow rate between 0 and 1000 sccm per meter of the first plasma source. g. A waterproof coating is deposited on the surface of the fabric substrate by exposing the fabric substrate to plasma from the first plasma source.

2. The method of claim 1, further comprising the following stages: a. Degas the substrate to a degassing level of up to 6.7 Pa; b. Providing a second plasma source of the linear hollow cathode type, the second plasma source comprising at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator for surface activation of the fabric substrate, wherein the surface activation and waterproof coating deposition of the method are performed at a pressure between 0.005 and 0.050 Torr; c. Inject a second plasma generating gas into the electrodes of the second plasma source at a flow rate between 1500 and 4500 sccm per linear meter of the second plasma source, wherein the second plasma generating gas includes N2, O2, or a mixture of O2 and N2 or N2O; d. Supply a second power to the second plasma source such that the second power density of the plasma is between 0.5 kW and 15 kW per meter of the second plasma source, and e. The surface of the fabric substrate is activated by exposing the fabric substrate to plasma from the second plasma source, and then the waterproof coating is deposited on the surface of the fabric substrate by exposing the fabric substrate to plasma from the second plasma source.

3. The method according to claim 1 or 2, characterized in that, The fluorinated monomer has the following formula: a.C n F 2n+1 C m X 2m CR1Y-OCO-C(R2) CH2 Where n is 2 to 6, m is 0 to 9, X and Y are H, F, Cl, Br or I, R1 is H or alkyl or substituted alkyl and R2 is H or alkyl or substituted alkyl.

4. The method of claim 2, further comprising degassing the fabric substrate before or simultaneously with activating the surface of the fabric substrate.

5. The method according to claim 1, wherein, The fabric substrate is a fabric processed on a roller in a roller-to-roll process.

6. The method according to claim 1, characterized in that, The first plasma generating gas includes He, Ar, or a mixture of He and Ar.

7. The method according to claim 6, characterized in that, The first plasma generating gas comprises a mixture of He and Ar, wherein the atomic ratio of He / Ar is between 0.5 and 10.

8. The method according to claim 2, characterized in that, The duration of exposure of the fabric substrate to the plasma from the second plasma source is between 4 and 12 seconds.

9. The method according to claim 1, characterized in that, The ratio of the first plasma generating gas flow rate to the fluorinated monomer flow rate is at least 1.

10. The method according to claim 1, wherein, The temperature of the fabric substrate is up to 40°C during surface activation and deposition of the waterproof coating in the absence of a cooling device in contact with the fabric substrate.

11. The method according to claim 6, characterized in that, The first plasma generating gas comprises a mixture of He and Ar, wherein the atomic ratio He / Ar is between 3.5 and 5.

5.

12. The method according to claim 1, characterized in that, The ratio of the first plasma generating gas flow rate to the fluorinated monomer flow rate is between 1 and 20.

13. The method according to claim 2, wherein, The surface activation and waterproof coating deposition of the method are carried out under a pressure between 0.010 and 0.030 Torr.

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