Permeable composite nanofiber-based multilayer textile

Abstract

A composite multilayer textile (1) is disclosed that includes at least one nanofiber layer (11) having nanofibers with a diameter of less than 100 nm and one support layer (12) having microfibers with a diameter of less than 3 microns, wherein the layers (11, 12) are produced by electrospinning, and the multilayer textile (1) exhibits a typical transmittance (T%) at λ=550 nm of greater than 60%, exhibiting improved properties with respect to permeability, breathability, and robustness. This is achieved by fusing at least one nanofiber layer (11) and a support layer (12) to form solid regions (Ds) in the multilayer textile (1) in the closed areas of the pattern used in the production process, the solid regions (Ds) being separated or connected from each other and exhibiting defined shapes with regular or irregular spatial distribution, while the fiber shape of the nanofibers of the nanofiber layer (11) and the microfibers of the support layer (12) is maintained on top of the open areas next to the solid regions (Ds), achieving a general permeability greater than the permeability given by the sum of the individual layers (11, 12).

Description

Technical Field

[0001] The present invention describes a composite multilayer textile comprising at least one nanofiber layer having nanofibers with a diameter below 100 nm and one support layer having microfibers with a diameter below 5 microns, wherein the layers are produced by electrospinning, and the multilayer textile shows an overall transmittance at λ = 555 nm greater than 60%, a method for producing a permeable multilayer textile, and the use of the multilayer textile as part of a face mask.

Background Art

[0002] Multilayer textiles have been used for many years in various applications. An interesting application is their use as a permeable and breathable mask or face mask. Such high-performance textiles are continuously being developed to provide optimal permeability and breathability characteristics. In recent years, nanotechnology has been introduced in the form of nanofibers. The motivation is the well-known fact that nanofibers can be used to synthesize filter layers with excellent filtration efficiency by achieving maximum breathability. However, due to the extremely small fiber diameter and fragile nanofibers, the stability of the resulting multilayer textile has to be increased in order to reach a more robust multilayer textile.

[0003] From WO2016128844 it is known to use electrospinning to produce at least one layer of the resulting permeable composite multilayer textile. After electrospinning at least one layer with nanofibers, this layer is arranged between two fabric layers that are used as cover layers. The cover layers should be nonwoven layers and the nanofiber layer should be electrospun onto the cover layers. Electrospinning is described in detail in WO2016128844 and even the coating step of the nanofiber layer onto the cover layers is carried out via electrospinning.

[0004] Regarding scientific papers, several documents were found in scientific papers regarding the possibility of creating semi-permeable air filters via electrospinning. In Xia et al. [Xia T, Bian Y, Zhang L, Chen C. Relationship between pressure drop and face velocity of electrospun nanofiber filters. Energy Build. 2018;158:987-999], the possibility of creating permeable nanofiber membranes was presented, and it was explained how such elements could be used to combine high particle removal efficiency with relatively low air resistance. An initial approach to scaling up the production of nanofiber-based permeable air filters was reported by Xu et al. [Xu J, Liu C, Hsu PC et al. Roll-to-roll transfer of electrospun nanofiber films for high-efficiency permeable air filters. Nano Lett. 2016;16(2):1270-1275].

[0005] However, no convincing solution has yet been proposed for the cost-effective synthesis of permeable face masks with appropriate properties in all relevant aspects such as filtration, permeability, breathability, and robustness.

Summary of the Invention

[0006] The subject of the invention is to provide a permeable composite nanofiber-based multilayer textile, a method for producing such a multilayer textile, and the use of such a multilayer textile as part of a face mask.

[0007] The permeable composite nanofiber-based multilayer textile must later be designed, for example, to produce a see-through face mask that has appropriate mechanical stability and complies with the European rules EN14683 or EN149:2001+A1:2009, which are European standards for personal protective equipment. No technical solution has yet been disclosed for realizing a cost-effective, permeable face mask that has good performance in all of the aforementioned important features, namely filtration efficiency, splash resistance, and comfort.

[0008] The invention essentially provides a multilayer textile as a permeable polymer filter, which has a large filtering capacity for microparticles and nanoparticles due to the small size of its pores and adjustable fiber surface properties, and the main target is bacteria in the range of 0.5 to 3 microns. The material can be used to produce various types of permeable filters capable of removing a wide range of harmful bacteria and contaminants from air and other fluids.

[0009] A further understanding of the various aspects of the invention can be obtained by referring to the following detailed description in conjunction with the related drawings briefly described below. It should be noted that in embodiments described differently, the same parts are provided with the same reference symbols or the same component names, and the disclosure included throughout the description may be similarly applicable to the same parts having the same reference symbols or the same component symbols.

[0010] Preferred exemplary embodiments of the subject matter of the invention are described below in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0011]

Fig. 1a

Fig. 1b

Fig. 1c

Fig. 1d

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Fig. 2b

Fig. 2c

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Fig. 3b

DETAILED DESCRIPTION OF THE INVENTION

[0012] A permeable composite multilayer textile 1 is disclosed that comprises a sandwich structure of at least one nanofiber layer 11 having ultrathin nanofibers with a diameter of less than at least 100 nm, particularly less than 50 nm, and at least one semipermeable support layer 12 comprising larger and more robust microfibers with a diameter of preferably 1 to 5 μm. At least one monolayer of the nanofiber layer 11 and the support layer 12 is used, and each is electrospun on top of the other in an electrospinning step I on a belt 2 of a production setup 0.

[0013] The sizes of the fibers constituting layers 11 and 12 are optimized to reduce light scattering and enhance transparency. The optimal fiber sizes are selected according to predictions formulated using Mie theory of light scattering. The amount of scattered light is lower in fibers with diameters significantly smaller or larger than the wavelength of the incident light. Thus, our strategy is based on a multilayer textile comprising low-scattering fibers of different sizes that each contribute to filtration and mechanical properties.

[0014] After electrospinning step 1, a subsequent second step II in the form of a thermo-mechanical treatment step II is applied to the multilayer composite. The multilayer composite passes through a press 3 or most preferably a calendar 3 having at least one squeezing roll 30.

[0015] - A pressure p1 of at least 1000 N / cm2, most preferably 1500 N / cm2 or more, and - A temperature T1 of at least 70 °C, most preferably 80 °C or more, are applied for a time interval Δt of up to one digit of seconds, preferably 10 seconds or more, most preferably 30 seconds, As shown in Figure 1b, the nanofibers of the nanofiber layer 11 and the microfibers of the support layer 12 are integrally fused at specific locations to form a solid region Ds, which has high permeability. Depending on the materials used and the thickness of the fibers, the permeability of the solid region Ds is higher than that of other regions.

[0016] The solid region Ds provides strong bonding points between layers 11 and 12, significantly improving mechanical stability and permeability. According to the first method, the collector of the electrospinning device has closed and open regions with a specific pattern in the plane and will also function as a template. A suitable patterned collector can be a metal mesh or a perforated metal sheet. On an industrial scale, the collector can conveniently be integrated into the belt 2 to enable the pattern to be transferred to each of the layers 11, 12, and the final multilayer textile 1.

[0017] In a typical design, the multilayer textile 1 presents a pattern in which regions composed of in-plane aligned fibers are embedded in a continuous solid network formed by fiber fusion. As a result, there is a fused patterned multilayer structure having a pattern corresponding to the pattern of the collector of the electrospinning device. The connection regions of the different layers 11, 12 are formed by the pattern. The hot pressing and patterning are the result of the electrospinning step I on the patterned collector and the subsequent thermomechanical treatment step II.

[0018] In a subsequent step, the cooling step III is carried out at a temperature T2 and a pressure pat that are below T1 and p1 by the thermomechanical treatment step II. The temperature T2 is well below T1, particularly on the order of room temperature below 30 °C. The pressure pat is the atmospheric pressure on the resulting multilayer textile 1 after passing through the press / calendar 3.

[0019] The resulting multilayer textile 1 having a patterned, fused, at least partially connected nanofiber layer 11 and a support layer 12 can then be further processed or wound up on the roll 4.

[0020] A schematic example of a multilayer textile 1 based on a permeable composite nanofiber showing a patterned structure is shown in Figure 1b. The pattern comprises solid regions Ds of the nanofiber layer 11 and the support layer 12, which are characterized by higher permeability and fibrous regions of the nanofiber layer 11 and the support layer 12 that provide breathability and filtration.

[0021] The fibers are constructed in a multilayer structure composed of a nanofiber layer 11 of chitosan / polycaprolactone nanofibers and a support layer 12 of polyester / polyurethane microfibers that are fused as described above.

[0022] In a more preferred example, the nanofiber layer 11 of chitosan / polycaprolactone nanofibers is embedded between two protective support layers 12, 12' of polyester / polyurethane microfibers, as schematically shown in Fig. 1c. All three layers 11, 12, 12' were continuously spun on the special conductive collector of the electrospinning device as described above, and subsequently changed via the thermomechanical treatment step II to generate the solid region Ds.

[0023] The example of Fig. 1c was generated as described above. The sample shows the structure according to Fig. 1d of the enclosed microscopic image. The solid region Ds of the multilayer textile 1' can be clearly visualized and corresponds to the pattern of the collector of the electrospinning device.

[0024] The thicknesses of the nanofiber layer 11 and the support layer 12 can be adjusted and selected to provide various properties to the multilayer textile 1 and can be appropriate. The fibers are electrospun in a subsequent step to conveniently construct the multilayer architecture. At the end of the sequence of electrospinning step I, a multilayer sheet with different fiber densities is formed over the open and closed regions of the collector. The multilayer textile 1 is then hot pressed in the thermomechanical treatment step II. This step II can be conveniently carried out on an industrial scale via calendering. Due to the combined effect of heat and pressure, the polymer fibers in contact with the closed region of the collector are deformed into a solid compression film, while above the open region of the collector, the fiber form is maintained. At the end of this stage, the patterned multilayer textile 1 is formed. The nanofibers of the nanofiber layer 11 and the microfibers of the support layer 12 reach or extend over the open region of the structure beside the solid region Ds, where they can be distinguished from each other. The thermomechanical treatment step II enables the simultaneous bonding of the different layers 11, 11', 12, 12', 13 (as disclosed below) and the generation of a pattern with the solid region Ds in the patterned multilayer textile 1, thereby increasing the permeability and mechanical resistance.

[0025] By realizing a solid region Ds embedded in a continuous network of nanofibers and microfibers of at least one nanofiber layer 11 and at least one support layer 12, the size, shape, density, and spatial arrangement of the solid region Ds can be changed to adjust the final appearance and barrier properties of the multilayer textile 1.

[0026] To achieve higher toughness, based on the above description, the production method was changed to also yield a permeable composite nanofiber-based multilayer textile 1''. Such industrial production of the multilayer textile 1'' is achieved by this slightly modified process.

[0027] The production method starts, as described above, from an electrospinning step I of at least one nanofiber layer 11 and at least one support layer 12 having microfibers on the belt 2 and the collector of the electrospinning device. At this time, the collector does not need to show a press pattern. The electrospun layers 11, 12 are further conveyed, and a further patterned layer 13 or a porous substrate 13 is preferably provided from a roll as shown in Figure 2a. Before this, the three layers 11, 12, 13 are fed to a press 3 or a calendar 3, where the layers 11, 12, 13 are subjected to a heat / pressure treatment in a thermomechanical treatment step II.

[0028] - A pressure p1 of at least 1000 N / cm2, most preferably 1500 N / cm2 or more, and - A temperature T1 of at least 70 °C, most preferably 80 °C or more, By applying for a time interval Δt of up to one digit of seconds, preferably 10 seconds or more, most preferably 30 seconds, The nanofibers of the nanofiber layer 11, the microfibers of the support layer 12, and the material of the patterned layer 13 are integrally fused to form a solid region Ds in the closed region of the patterned layer 13, which has high permeability.

[0029] Depending on the materials used and the thickness of the fibers, the permeability of the solid region Ds is higher than that of other regions.

[0030] By introducing the patterned layer / porous substrate layer 13, the nanofiber layer 11 and the support layer 12 are connected at the surface of the patterned layer / porous layer 13.

[0031] The patterned layer / porous substrate layer 13 is formed as a polymer mesh having a pattern 130 with openings and connecting webs. The patterned layer / porous substrate layer 13 can be a woven fabric or a fleece, and comprises fibers having a diameter of 20 microns or more, in particular from about 50 microns to 200 microns, and forms a connecting web. At least 30% of the surface of the patterned layer / porous substrate layer 13 should be open, forming various openings. The pattern 130 is most preferably regular, but can also be formed irregularly.

[0032] The patterned layer / porous substrate layer 13 can also be formed as a foil of a thermoplastic material having a plurality of through-holes as openings and a lattice structure as a connecting web, and at least 30% of the surface should be open. The openings of the through-holes must be selected such that the connecting web of the lattice structure is wider than 20 microns, in particular more than 50 microns.

[0033] The patterned layer 13 must be semi-permeable or permeable so as to achieve the highest possible permeability later. Such a patterned layer 13 is introduced after the electrospinning step I and before the thermo-mechanical treatment step II, and is further shaped into layers 11, 12 as a disappearing shape.

[0034] Due to the pattern 130 on or in the patterned layer 13 and the thermo-mechanical treatment step II, the nanofiber layer 11 and the support layer 12 are fused at the grid connections or in the closed regions of the lattice structure of the patterned layer 13, as shown in Figure 2b.

[0035] When two double layers of nanofiber layers 11, 11' and support layers 12, 12' enclose the patterned layer 13 and are fused with each other and with the patterned layer 13, a multilayer textile 1''' according to the schematic diagram of FIG. 2c is realized. We generated such a multilayer textile 1''' shown in FIGS. 2d and 2e of the SEM images by the above method.

[0036] By the thermomechanical treatment step II at T1, p1 and the subsequent cooling step III at T2, pat as described above, a solid region Ds is formed. In this case, the patterned layer 13 remains in the resulting multilayer textile 1. The pattern 130 constructs the fusion positions of the nanofibers and microfibers of the layers 11, 12. The patterned layer / porous substrate layer 13 is used as a disappearing shape, and the nanofibers and microfibers are also permanently attached to the patterned layer / porous substrate layer 13. The fused connections described herein permanently connect different layers.

[0037] The resulting pattern or pattern islands of the solid region Ds are similar in both manufacturing processes, but the first procedure can be carried out without introducing the patterned layer 13.

[0038] The use of nanofiber layers 11, 11' comprising chitosan / polycaprolactone nanofibers and support layers 12, 12' comprising polyester / polyurethane microfibers is particularly preferred.

[0039] The disclosed method results in multilayer textiles 1, 1', 1'', 1''' having a transmittance T% which is a ratio of the incident electromagnetic force in the visible spectrum transmitted through the sample greater than 50%. Most preferably, the transmittance of the final multilayer textiles 1, 1', 1'', 1''' after the thermomechanical treatment step I with selective melting of some regions should be greater than 60%.

[0040] Each of the individual layers 11, 11', 12, 12', 13 must block or scatter only 20% of visible light, which means that 80% of the incident photons in the visible spectrum can cross the film without being absorbed or refracted. The transmittance (T%) must be greater than 80% at λ = 555 nm. The light wavelength of 555 nm corresponds to the maximum sensitivity of human vision, and thus the T% at this specific wavelength is particularly relevant to the applications targeted by the present invention.

[0041] In practice, the following results could be achieved. - Nanofiber layer 11 with nanofibers having a diameter of 50 nm: T% > 90 - Support layer 12 with microfibers having a diameter of 1 - 2 μm: T% > 80 - Patterned layer 13 as a woven commercial polymer mesh: T% = 70 before modification and T% = 80 after modification by hot pressing.

[0042] The transmittance of the final overall or general multilayer textile 1, 1', 1'', 1''' is given by the product of the individual layers. By selectively melting the fibers in some regions to achieve solid regions Ds, the present inventors can achieve a transmittance value greater than the value of the transmittance given by the sum of the individual components 11, 11', 12, 12', 13.

[0043] The size of the pattern island of the pattern of the collector of the electrospinning device or the pattern island of the pattern 130 of the patterned layer 13, and together with that, the lateral width of the subsequent solid region Ds can vary between 1 cm and 10 nm, preferably between 1 mm and 1 μm, more preferably between 100 μm and 10 μm at its maximum point.

[0044] Pattern island parts having a maximum dimension of less than 100 μm are substantially invisible to the naked eye and have the advantage of producing a multi-layer textile 1 with a homogeneous appearance. The pattern island parts can be arranged according to a regular pattern or an irregular pattern. The pattern can be homogeneous throughout the multi-layer textile 1 or can present a gradient of pattern island part concentration that gives specific properties to various regions of the multi-layer textile 1 or subsequent face masks.

[0045] The surface of all the pattern island parts and the solid region Ds obtained therewith should constitute 5% to 95%, preferably 15% to 85%, more preferably 30% to 70% of the total surface of the multi-layer textile 1.

[0046] The thickness of each solid region Ds of the compressed polymer region can be adjusted in addition to the film composition. The thickness of the solid region Ds can vary between 100 nm and 0.1 cm, preferably between 1 μm and 1 mm, more preferably between 10 μm and 100 μm.

[0047] The multi-layer textiles 1, 1', 1'', 1''' can be used as part of a face mask. Such multi-layer textiles 1, 1', 1'', 1''' can also be used in filtration applications as a filtration membrane or as a packaging material.

[0048] It is most preferable to use a chitosan-polycaprolactone mixture for the nanofiber layer 11 and / or the support layer 12. Chitosan is widely available, biodegradable, renewable, and can be extracted from various biomasses. Chitosan is non-cytotoxic, contains inherent antibacterial properties, and can be electrospun. Furthermore, a special molecular structure characterized by a large number of polar amino groups is expected to enhance the filtration efficiency. Polycaprolactone also has high biocompatibility and biodegradability. The chitosan-based functional multi-layer textile 1 has high permeability (T>90%), and the reduced pore size is associated with promising filtration properties.

[0049] The main limitation can be seen in the mechanical stability of these small fibers. Therefore, we have discovered larger support fibers in the support layer 12. The support fibers we developed are based on polylactide, polyurethane, and their mixtures. Such support fibers have appropriate mechanical properties. Low crystallinity and large diameter minimize light scattering. Interestingly, both polymers are biodegradable.

[0050] Polylactic acid is entirely produced from starch, a renewable raw material, and polyurethane is synthesized using both fossil and renewable raw materials. In summary, we have developed formulations that enable us to control the fiber size, as well as their interfacial chemistry and crystallinity.

[0051] By controlling these critical parameters, we have enhanced / compatible the permeability, mechanical properties, and filtration efficiency. All polymers are biodegradable, and thus, the final products will have limited environmental impact if placed in landfills or scattered in the environment (e.g., they do not produce persistent microplastics). Furthermore, most of the raw materials are potentially, if not automatically, produced from renewable resources, reducing the carbon footprint.

[0052] Similar results can be obtained with many different polymers or polymer combinations that apply well-known principles of polymer chemistry and engineering. Substantially, any polymer or polymer combination that can be formed into permeable films and / or fibers can potentially be used. To optimize the properties of the material, it is also convenient to use appropriate additives (such as curing agents, plasticizers, surfactants, clarifiers, etc.) that can constitute up to 30% of the weight of the raw materials.

[0053] Polymers suitable for film and fiber production may include the following. - Polyolefins: LDPE, HDPE, PP, PS, PAN, PVC,... - Polyesters: PET, PLA, PCL, PHA, PHB,... - Polycarbonate: PC, ... - Polyether: PEG, PEO, ... - Polyamide, polyimide, polyaramide: PA (e.g., nylon), PI, PAr (e.g., Kevlar (Registered Trademark) ), ... - Polyurethane: PU, TPU, ... - Silicon polymer: PDMS, ... - Miscellaneous polymers: PVA, PVP, PMMA, PVAc, ... - Cellulose and its derivatives: ethyl cellulose, methyl cellulose, cellulose acetate, ... - Other natural polymers: hemicellulose, chitin, chitosan, starch, collagen (gelatin), ...

[0054] It is most advantageous to use biocompatible, biodegradable, and antibacterial thermoplastic polymers for the different layers 11, 12, 12’, 13.

[0055] The polymer mixtures of the different layers 11, 11’, 12, 12’, 13 are composed of at least one type of thermoplastic polymer, thermosetting polymer, elastic polymer, or thermoplastic elastomer polymer. More than one polymer can be used to form mixtures and composites to infer the desired final properties of the textile.

[0056] Two or more different types of fibers can be present in the multi-layer, nanofiber layer 11, support layers 12, 12’, and / or patterned layer 13 generated by electrospinning. Other parts of the above-described generation method can be appropriately used. The formation of the solid region Ds is the most important feature.

[0057] The application to the mask disclosed herein is a hygiene mask, face mask, surgical mask, or surgical mask in applications in different fields. Also, the protective clothing can be transparent for aesthetic reasons. The surgical drape should be transparent to better enable patient monitoring. Other uses are as window screens, semi-transparent window screens or haze window screens having a filtering effect on fine particles (PM2.5, PM10).

[0058] Such composite multilayer textiles 1 can also be used as packaging materials as highly breathable, air-permeable semi-permeable membranes for special packaging applications. These composite multilayer textiles prevent aerosol droplets, pollen, bacteria, spores, but allow viewing of the product and have very high evaporability. Those skilled in the art are familiar with the setup for the determination of light transmittance. Here, the transmittance was quantified by measuring the transmittance using an Agilent UV-vis spectrophotometer "Cary 4000". Samples are usually placed orthogonally to the incident light using a solid sample holder (Agilent) with a 1 cm 2 aperture mask. Of course, similar measurements are possible using a general optical spectrometer with an aperture mask of up to several square centimeters operating in the wavelength range of interest.

[0059] In practice, the permeable filter 1 mainly consists of two parts. That is, an electrospun nanofiber mat 11 as a filtering element and a support material made of a commercially available PLA mesh 12. To increase the permeability of the final product, the PLA mesh was pressed at 120 °C for 30 seconds with a pressure of 50 bar applied. The original PLA mesh essentially has antistatic properties that prevent the deposition of fibers during the electrospinning process. Therefore, a skin-compatible surfactant (TWEEN 80 (Registered Trademark) ) functioning as an antistatic substance was selected to coat the mesh by an immersion coating technique using a 1.0% by weight solution in ethanol. Then, the substrate thus prepared (pressed PLA + TWEEN 80 (Registered Trademark) ) was electrospun with a thin film of polyamide-11 (PA11) nanofibers (about 0.1 g / m 2) was directly coated. Using a 6 wt% solution in anisole formic acid, fibers with an average diameter of 72 ± 29 nm were obtained.

[0060] As shown in Figure 3a, the filtration efficiency was measured using a homemade setup. The following were used in each test. A circular test piece with a diameter of 46 mm; an aerosol composed of neutralized sugar particles with diameters ranging from 20 to 2000 nm; A pump system that generated a constant air flow of 8 L / min (air flow velocity 8 cm / s) through the test piece; A (real-time) particle analyzer "Cambustion DMS500" that measured the concentration of the aerosol diffusing through the test piece. The particle filtration efficiency is given as a percentage and is determined after achieving a steady-state flow of particles (after approximately 3 minutes) by comparing the aerosol concentration when using the filter system with the aerosol concentration when not using the filter system. The PLA-PA11 system of the multilayer textile 1 based on the permeable composite nanofiber showed good filtration efficiency for the neutralized fructose particle aerosol. It is >90% for a mobility particle diameter of 1 μm.

[0061] The air permeability of the medical face mask was evaluated according to the EN-14683:2019 standard. The air permeability is related to the pressure drop of the test material measured by applying a flow of 27 cm / s. The PLA-PA11 filter of the multilayer textile 1 based on the permeable composite nanofiber showed a pressure drop of 9 Pa / cm 2 (the limit for type I and II medical face masks is 40 Pa / cm according to EN-14683:2019 2 ). The permeability was quantified by measuring the transmittance of the filter using an Agilent UV-vis spectrophotometer "Cary 4000". The sample was 1 cm 2It is arranged perpendicular to the incident light using a solid sample holder (Agilent) with an aperture mask. Assuming that air has a transmittance of 100%, in this case, the PLA-PA11 filter of the permeable composite nanofiber-based multilayer textile 1 has a transmittance of 76% at λ = 555 nm (visible light ranges from approximately 400 to 800 nm). In the figure below, a photograph of the PLA-PA11 sample of the permeable composite nanofiber-based multilayer textile 1 is reported together with the UV-vis spectrum in Figure 3b.

[0062] List of reference numbers 0 Generation setup 1 Permeable composite nanofiber-based multilayer textile / membrane 11 Nanofiber layer (diameter less than 100 nm) 12, 12’ Support layer with microfibers (diameter 1 - 2 microns) 13 Patterned layer / porous substrate layer (woven / melt spun / melt blown / foil with openings) 130 Pattern 2 Belt (a collector of the electrospinning device may form part of the belt) 3 Press / calendar 30 Press roll 4 Roll (for multilayer textile) I Electrospinning step II Thermo-mechanical treatment step (T1, p1) III Cooling step (T2, pat) Ds Solid region (lateral thickness 1 μm - 100 μm, lateral width 10 μm - 100 μm)

Claims

1. A composite multilayer textile (1) comprising at least one nanofiber layer (11) having nanofibers with a diameter of less than 100 nm and one support layer (12) having microfibers with a diameter of less than 5 microns, wherein the layers (11, 12) are electrospun layers, and the composite multilayer textile (1) exhibits an overall visible light transmittance (T%) at λ = 555 nm greater than 50%. In the composite multilayer textile (1), the at least one nanofiber layer (11) and the support layer (12) are fused to form a solid region (Ds) in the closed region of the pattern used in electrospinning in the composite multilayer textile (1). The solid regions (Ds) are separated from or connected to each other. The fiber shapes of the nanofibers of the nanofiber layer (11) and the microfibers of the support layer (12) are maintained above the open region laterally of the solid region (Ds), achieving an overall visible light transmittance of the entire composite multilayer textile (1) that is greater than the transmittance provided by the sum of the individual layers (11, 12). The composite multilayer textile (1) is characterized in that.

2. The composite multilayer textile (1) according to Claim 1, wherein the composite multilayer textile (1) comprises a patterned layer (13) having a pattern (130) of closed and open regions on top of or at the bottom of the double layer (11, 12), and the solid region (Ds) is formed at the contact positions of the nanofiber layer (11), the support layer (12), and the patterned layer (13). The composite multilayer textile (1).

3. The composite multilayer textile (1) according to Claim 1, wherein the composite multilayer textile (1) comprises a nanofiber layer (11) sandwiched between two outer support layers (12, 12'), and shows a solid region (Ds) at the fusion position of all three layers (11, 12, 12'). The composite multilayer textile (1).

4. The composite multilayer textile (1) according to Claim 2, wherein the patterned layer (13) is sandwiched and fused between two pairs of nanofiber layers (11, 11') and support layers (12, 12'). The composite multilayer textile (1).

5. The composite multilayer textile (1) according to claim 2 or 4, wherein the solid region (Ds) connects the nanofiber layer (11, 11'), the support layer (12, 12'), and the patterned layer (13), and is formed as a contact region having a thickness of 1 μm to 100 μm, said composite multilayer textile (1).

6. The composite multilayer textile (1) according to any one of claims 1 to 5, wherein the solid region (Ds) exhibits a maximum lateral width of 10 μm to 100 μm at its maximum width point, said composite multilayer textile (1).

7. The composite multilayer textile (1) according to any one of claims 1 to 6, wherein the pattern of the solid region (Ds) on the composite multilayer textile (1) has a value of 30% to 70% of the entire surface of the composite multilayer textile (1), said composite multilayer textile (1).

8. The composite multilayer textile (1) according to any one of claims 2, 4 to 5, wherein the thickness of the patterned layer (13) varies between 1 μm and 100 μm, and the patterned layer (13) is based on a woven polymer mesh, said composite multilayer textile (1).

9. The composite multilayer textile (1) according to any one of claims 2, 4 to 5, wherein the thickness of the patterned layer (13) varies between 1 μm and 100 μm, and is formed of a thermoplastic material having several through holes as openings and a lattice structure as connecting webs, and at least 30% of the entire surface of the thermoplastic material is open, said composite multilayer textile (1).

10. The composite multilayer textile (1) according to any one of claims 1 to 9, wherein the nanofiber layer (11, 11') comprises chitosan / polycaprolactone nanofibers, and the support layer (12, 12') comprises polyester / polyurethane microfibers, said composite multilayer textile (1).

11. A method for producing an optically transmissive multilayer textile (1) exhibiting an overall visible light transmittance (T%) greater than 50% at λ = 555 nm, - An electrospinning step (I) of electrospinning a nanofiber layer (11, 11') and a support layer (12, 12') on a belt (2) of a production setup (0), either on a patterned collector of an electrospinning device or on a supplied patterned layer or a porous substrate layer (13), wherein the patterned collector or the patterned layer or the porous substrate layer (13) all exhibit open regions and closed regions, the electrospinning step (I), and - A conveying step of the belt (2) together with the coated multilayer (11, 11', 12, 12', 13) to a hot press or calender (3), and subsequently, - An implementation step of a thermomechanical treatment step (II) at an elevated temperature (T1) higher than room temperature and a pressure (p1) for a minimum time interval (Δt), wherein the layers (11, 11', 12, 12', 13) are fused in a closed region of either the pattern of the patterned collector or the pattern (130) of the patterned layer or the porous substrate layer (13), forming various solid regions (Ds) in the optically transmissive multilayer textile (1), the implementation step, and then, - A cooling step (III) performed at a reduced temperature (T2 < T1) and a pressure (pat < p1), characterized by the production method.

12. A method for producing an optically transmissive multilayer textile (1) according to claim 11, wherein the thermomechanical treatment step (II) is performed at a pressure (p1) of at least 1000 N / cm2, or 1500 N / cm2 or more, and a temperature (T1) of at least 70 °C, or 80 °C or more, the production method.

13. A method for producing an optically transmissive multilayer textile (1) according to claim 11 or 12, wherein a time interval (Δt) of 10 seconds or more, or 30 seconds is selected, the production method.

14. A method for producing an optically transmissive multilayer textile (1) according to one of claims 11 to 13, wherein the patterned collector of the electrospinning device is formed of a metal mesh or a perforated metal sheet and constitutes a part of the belt (2) or is integrated with the belt (2), the production method.

15. A method for producing an optically transmissive multilayer textile (1) according to one of claims 11 to 13, The method of production, wherein the patterned layer or the porous substrate layer (13) is formed by a woven polymer mesh or a thermoplastic foil having several through-holes as openings and a lattice structure as connecting webs, with at least 30% of the surface being open.

16. A method of producing an optically transmissive multilayer textile (1) according to one of claims 11 to 15, wherein two support layers (12, 12') are patterned and fused to one nanofiber layer (11) to form the solid region (Ds) in the closed regions of the pattern used.

17. A method of producing an optically transmissive multilayer textile (1) according to one of claims 11 to 15, wherein two pairs of nanofiber layers (11, 11') and support layers (12, 12') are fused in the closed regions of the pattern (130) of the patterned layer or the porous substrate layer (13).

18. A method of producing an optically transmissive multilayer textile (1) according to one of claims 11 to 17, wherein after the cooling step (III), the resulting multilayer textile (1, 1', 1'', 1''') is wound onto a roll (4).

19. Use of the multilayer textile (1, 1', 1'', 1''') according to one of claims 1 to 10 as a medical device and / or as part of a face mask as a personal protection device.

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