Transparent composite nanofiber-based multilayer textile

Abstract

A composite multilayer textile (1) comprising at least one nanofiber layer (11) with nanofibers having a diameter below 100 nm and one support layer (12) with microfibers having a diameter below 3 microns, wherein the layers (11, 12) are produced by electrospinning and the multilayer textile (1) shows an overall transmittance (T%) at λ = 550 nm of more than 60%, the textile showing improved properties related to transparency, breathability and strength. The textile is achieved by fusing the at least one nanofiber layer (11) and the support layer (12) at closed areas of the pattern used during production, thereby forming solid domains (Ds) in the multilayer textile (1), wherein the solid domains (Ds) are separated or connected from each other, showing defined shapes with regular or irregular spatial distribution, while the fiber morphology of the nanofibers of the nanofiber layer (11) and the microfibers of the support layer (12) is preserved on top of the open areas next to the solid domains (Ds), thereby achieving an overall transmittance which is greater than the sum of the transmittances 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 less than 100 nm and a support layer having microfibers with a diameter less than 5 micrometers, wherein the layer is produced by electrospinning, and the multilayer textile exhibits a total transmittance of greater than 60% at λ = 555 nm; a method for producing a transparent multilayer textile; and the use of the multilayer textile as part of a face mask. Background Technology

[0002] Multilayer textiles have long been used in a variety of applications. One application of interest is their use as transparent and breathable masks or face shields. Such high-performance textiles are constantly being developed to achieve optimal transparency and breathability. Recently, nanotechnology in the form of nanofibers has been introduced. The rationale is the well-known fact that nanofibers, by achieving maximum breathability, can be used to synthesize filter layers with excellent filtration efficiency. However, due to the extremely small fiber diameter and weak nanofibers, the stability of the resulting multilayer textiles must be increased to achieve stronger and more durable multilayers.

[0003] It is known from WO2016128844 that electrospinning is used to produce at least one layer of a transparent composite multilayer textile. After electrospinning to have at least one layer of nanofibers, this layer is placed between two textile layers serving as a cover layer. The cover layer should be a nonwoven layer and the nanofiber layer should be electrospinned onto the cover layer. Electrospinning is described in detail in WO2016128844, and even the step of coating the nanofiber layer onto the cover layer is performed by electrospinning.

[0004] Regarding scientific literature, several works were found concerning the possibility of preparing semi-transparent air filters via electrospinning. The possibility of preparing transparent nanofiber films was proposed in Xia et al.'s [Xia T, Bian Y, Zhang L, Chen C. Relationship between pressure drop and face velocity for electrospun nanofiber filters. EnergyBuild. 2018; 158: 987-999], and the possibility of combining high particle removal efficiency with relatively low air resistance using such elements was demonstrated. An early method for scaling up the production of nanofiber-based transparent air filters was reported in Xu et al.'s [Xu J, Liu C, Hsu PC et al. Roll-to-Roll Transfer of Electrospun Nanofiber Film for High-Efficiency Transparent AirFilter. Nano Lett. 2016; 16(2): 1270-1275].

[0005] However, no convincing solution has yet been proposed for the cost-effective synthesis of transparent face shields with sufficient properties in all relevant aspects such as filtration, transparency, breathability, and toughness. Summary of the Invention

[0006] The subject of this invention is to provide a transparent 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 transparent composite nanofiber-based multilayer textiles must be designed to later manufacture transparent face shields, for example, with sufficient mechanical stability and compliance with European regulations EN 14683 or EN149:2001+A1:2009 (European standards for personal protective equipment). No technical solution has yet been disclosed for achieving cost-effective transparent face shields with good performance in all the aforementioned key characteristics (i.e., filtration efficiency, splash resistance, and comfort).

[0008] This invention essentially provides a multilayer textile as a transparent polymer filter, which, due to its small pore size and tunable fiber surface properties, possesses significant filtration potential for both micron and nanoparticles, with a primary target being bacteria ranging from 0.5 to 3 microns. The material can be used to manufacture various types of transparent filters capable of removing a wide range of harmful microorganisms and contaminants from air and other fluids. Attached Figure Description

[0009] A further understanding of various aspects of the invention can be obtained by referring to the detailed description below in conjunction with the associated drawings briefly described below.

[0010] It should be noted that in different described embodiments, the same parts are provided with the same reference symbols or the same component names, and the disclosure contained throughout the specification can be similarly applied to the same parts having the same reference symbols or the same component symbols.

[0011] Preferred exemplary embodiments of the subject matter of the present invention are described below with reference to the accompanying drawings.

[0012] Figure 1a A schematic diagram illustrates a method for producing an electrospun nanofiber layer and a support layer comprising microfibers by electrospinning and continuous heat / pressure treatment and cooling steps on a patterned collector. The diagram shows a schematic setup.

[0013] Figure 1b Showing the use of according to Figure 1a The method yields a schematic cross-sectional view of a patterned multilayer textile obtained from two layers, while

[0014] Figure 1c A schematic cross-sectional view of a multilayer textile with a nanofiber layer sandwiched between two support layers is shown.

[0015] Figure 1d Shown as our laboratory according to Figure 1c A top-view scanning electron microscope image of an example of sample synthesis.

[0016] Figure 2a The diagram illustrates different production methods using schematic settings, while

[0017] Figure 2b Showing the use of according to Figure 2a A schematic cross-sectional view of a patterned multilayer textile obtained by the method and two layers, the patterned multilayer textile having a nanofiber layer, a support layer, and a solid domain of the patterned layer, while

[0018] Figure 2c A schematic cross-sectional view is shown of a multilayer textile with a patterned layer sandwiched between two bilayers, one containing a nanofiber layer and the other a support layer.

[0019] Figure 2d and Figure 2e The magnification is shown as an increase in magnification. Figure 2a A top-view scanning electron microscope image of an example synthesized by the method shown in the figure.

[0020] Figure 3a A schematic diagram of the measurement setup is shown, while

[0021] Figure 3b Photographs of the resulting transparent composite nanofiber-based multilayer textile and transmittance curves in the wavelength range between 300 nm and 800 nm are shown. Detailed Implementation

[0022] A transparent composite multilayer textile 1 is disclosed, comprising a sandwich structure of at least one nanofiber layer 11 and at least one translucent support layer 12. The nanofiber layer has ultrathin nanofibers with a diameter of at least less than 100 nm, particularly less than 50 nm, and the support layer comprises larger, stronger microfibers, preferably with a diameter between 1 μm and 5 μm. Using at least one monolayer of the nanofiber layer 11 and the support layer 12, in electrospinning step I, each layer is electrospun on top of the other on a belt 2 in production setting 0.

[0023] The fiber sizes constituting layers 11 and 12 were optimized to reduce light scattering and improve transparency. The optimal fiber size was selected based on predictions elaborated using Mie light scattering theory. Fibers with diameters significantly smaller or larger than the incident light wavelength scatter less light. Therefore, our strategy is based on multilayer textiles comprising low-scattering fibers of different sizes, each responsible for filtration and mechanical properties.

[0024] Following the electrospinning step I, a subsequent second step II, in the form of a thermomechanical treatment step II, is applied to the multilayer composite material. The multilayer composite material is then passed through a press 3 having at least one pressure roller 30, or most preferably through a calender 3.

[0025] By applying

[0026] - A pressure p1 of at least 1000 N / cm², preferably greater than or equal to 1500 N / cm² and

[0027] -A temperature T1 of at least 70°C, most preferably greater than or equal to 80°C,

[0028] Within a time interval Δt of up to a single digit in seconds, preferably greater than or equal to 10 seconds, and most preferably 30 seconds,

[0029] The nanofibers of nanofiber layer 11 and the microfibers of support layer 12 are fused together at specific locations to form a solid domain Ds, such as... Figure 1b As depicted, these solid domains are highly transparent. Depending on the material used and the fiber thickness, the transparency of solid domain Ds is higher than that of other regions.

[0030] Solid domains Ds provide strong bonding points between layers 11 and 12, thereby greatly improving mechanical stability and transparency. According to the first method, the collector of the electrospinning device has a specific pattern of closed and open areas in the plane and also serves as a template. A suitable patterned collector can be a metal mesh or a perforated metal sheet. On an industrial scale, the collector can be conveniently integrated into belt 2 to enable the transfer of the pattern to each layer 11, layer 12, and the final multilayer textile 1.

[0031] In a typical design, the multilayer textile 1 exhibits a pattern in which domains composed of in-plane aligned fibers are embedded in a continuous solid network created by fiber fusion. The result is a fused patterned multilayer structure with a pattern corresponding to the pattern of the collector in the electrospinning apparatus. The connection regions of the different layers 11, 12 are formed by the pattern. Hot pressing and patterning are the result of electrospinning step I and subsequent thermomechanical treatment step II performed on the patterned collector.

[0032] In the subsequent steps, cooling step III is carried out at a temperature T2 and a pressure pat lower than those of T1 and p1 in thermomechanical treatment step II. The temperature T2 is much lower than T1, specifically room temperature about 30°C lower than the room temperature. The pressure pat is the atmospheric pressure on the multilayer textile 1 obtained after leaving the press / calender 3.

[0033] The resulting multilayer textile 1, which has patterned, fused, at least partially connected nanofiber layers 11 and support layers 12, can then be further processed or wound onto rollers 4.

[0034] Figure 1b A schematic example depicting a transparent composite nanofiber-based multilayer textile 1 is shown, illustrating a patterned structure. The pattern comprises solid domains Ds of a nanofiber layer 11 and a support layer 12, characterized in that the increased transparency of the nanofiber layer 11 and the support layer 12, along with the fiber domains, imparts breathability and filtration.

[0035] The fibers are organized in a multilayer structure consisting of a nanofiber layer 11 of chitosan / polycaprolactone nanofibers fused together as described above and a support layer 12 of polyester / polyurethane microfibers.

[0036] In a more preferred example, the nanofiber layer 11 of the chitosan / polycaprolactone nanofibers is embedded between the two protective support layers 12, 12' of the polyester / polyurethane microfibers, such as... Figure 1c The diagram is shown schematically. All three layers 11, 12, 12' are spun sequentially on a special conductive collector of an electrospinning apparatus and subsequently modified by thermomechanical treatment step II as described above to produce the solid domain Ds.

[0037] Figure 1cThe example is produced as described. The sample shows [something] according to [the instructions]. Figure 1d The structure of the attached microscopic image. The solid domain Ds of the multilayer textile 1' is clearly visible and corresponds to the pattern of the collector of the electrospinning device.

[0038] The thicknesses of the nanofiber layer 11 and the support layer 12 can be adjusted to provide selected and appropriately varied multilayer textiles 1 with different properties. The fibers are electrospun in subsequent steps to facilitate the construction of a multilayer architecture. At the end of the electrospinning step I sequence, a multilayer sheet comprising different fiber densities is formed over the open and closed regions of the collector. The multilayer textile 1 is then hot-pressed in a thermomechanical treatment step II. This step II can be conveniently performed on an industrial scale by calendering. The combined action of heat and pressure transforms the polymer fibers in contact with the closed regions of the collector into a solid, dense film, while the fiber morphology is preserved on top of the open regions of the collector. At the end of this stage, a patterned multilayer textile 1 is formed.

[0039] The fibrous morphology of the nanofibers in the nanofiber layer 11 and the microfibers in the support layer 12 extends to or over the open region of the structure next to the solid domain Ds, where they can be distinguished from each other.

[0040] Thermomechanical treatment step II allows for the simultaneous bonding of different layers 11, 11', 12, 12', 13 (as disclosed below) and the generation of patterns of solid domains Ds in the patterned multilayer textile 1, which increase transparency and mechanical resistance.

[0041] By obtaining solid domains Ds in a continuous network of nanofibers embedded in at least one nanofiber layer 11 and microfibers in at least one support layer 12, the size, shape, density, and spatial arrangement of the solid domains Ds can be modified to adjust the final appearance and barrier properties of the multilayer textile 1.

[0042] To achieve higher strength and toughness, based on the above description, the production method was modified, resulting in the production of transparent composite nanofiber-based multilayer textiles 1". Through this slightly modified process, the industrial production of such multilayer textiles 1” was achieved.

[0043] The production method begins with an electrospinning step I on a collector of a belt 2 and an electrospinning apparatus, consisting of at least one nanofiber layer 11 and at least one support layer 12 having microfibers. In this step, the collector does not need to display a press pattern. The electrospun layers 11, 12 are further fed and provided with an additional patterned layer 13 or porous substrate 13, preferably from, for example... Figure 2a The roles depicted. Then, the three layers 11, 12, and 13 are fed into the press 3 or calender 3, where layers 11, 12, and 13 undergo heat / pressure treatment in thermomechanical treatment step II.

[0044] By applying

[0045] - A pressure p1 of at least 1000 N / cm², preferably greater than or equal to 1500 N / cm² and

[0046] -A temperature T1 of at least 70°C, most preferably greater than or equal to 80°C,

[0047] Within a time interval Δt of up to a single digit in seconds, preferably greater than or equal to 10 seconds, and most preferably 30 seconds,

[0048] The nanofibers of the nanofiber layer 11, the microfibers of the support layer 12, and the material of the patterned layer 13 are fused together to form solid domains Ds in the closed regions of the patterned layer 13. These solid domains are highly transparent.

[0049] Depending on the materials used and the fiber thickness, the transparency of the solid domain Ds is higher than that of other regions.

[0050] Due to the introduction of the patterned layer / porous substrate 13, the nanofiber layer 11 and the support layer 12 are connected at the surface of the patterned layer / porous layer 13.

[0051] The patterned layer / porous substrate 13 is formed as a polymer web having a pattern 130, the polymer web including openings and connecting webs. The patterned layer / porous substrate 13 may be a woven fabric or a pile fabric comprising fibers with a diameter of 20 micrometers or more, particularly about 50 micrometers to 200 micrometers, forming the connecting webs. At least 30% of the surface of the patterned layer / porous substrate 13 should be open, thereby forming multiple openings. The pattern 130 is most preferably regular, but can also be irregularly formed.

[0052] The patterned layer / porous substrate 13 may also be formed as a thermoplastic foil having a plurality of through holes as openings and a mesh structure as connecting webs, wherein at least 30% of the surface should be open. The aperture of the through holes must be selected such that the connecting webs of the mesh structure are 20 micrometers or more, particularly 50 micrometers or more wide.

[0053] The patterned layer 13 must be semi-transparent or transparent in order to achieve the highest possible transparency later. This patterned layer 13 is introduced after the electrospinning step I and before the thermomechanical treatment step II, and is further cast into layers 11 and 12 in a lossy form.

[0054] Due to the pattern 130 on or within the patterned layer 13 and the thermomechanical processing step II, the nanofiber layer 11 and the support layer 12 are fused at the grid connections or closed regions of the grid structure of the patterned layer 13, such as... Figure 2b The description.

[0055] If the two bilayers of nanofiber layers 11, 11' and support layers 12, 12' surround the patterned layer 13 and fuse together with each other and the patterned layer 13, then the desired result is obtained according to... Figure 2c The schematic diagram shows a multi-layered textile 1”'. We produced this multi-layered textile 1”' using the method described above, wherein the multi-layered textile... Figure 2d and Figure 2e The SEM images are used to depict the scene.

[0056] Due to the thermomechanical treatment step II at T1 and p1 as described above, and the subsequent cooling step III at T2 and p1, a solid domain Ds is formed. In this case, the patterned layer 13 is retained in the resulting multilayer textile 1. The pattern 130 constitutes the fusion site of the nanofibers of layer 11 and the microfibers of layer 12. The patterned layer / porous substrate 13 is used in a loss-of-use manner, while the nanofibers and microfibers are also permanently attached to the patterned layer / porous substrate 13. The fusion joints described herein permanently connect the different layers.

[0057] Although the resulting solid domains Ds patterns or patterned islands are similar in both manufacturing processes, the first process can be run without introducing the patterning layer 13.

[0058] Particularly preferred are nanofiber layers 11, 11' comprising chitosan / polycaprolactone nanofibers and support layers 12, 12' comprising polyester / polyurethane microfibers.

[0059] The disclosed method produces multilayer textiles 1, 1', 1”, 1”' with a transmittance T% greater than 50%, where transmittance is generally the fraction of incident electromagnetic power in the visible spectrum transmitted through the sample. Most preferably, after thermomechanical treatment step I and selective melting of certain areas, the final transmittance of the multilayer textiles 1, 1', 1”, 1”' should be greater than 60%.

[0060] Each individual layer 11, 11', 12, 12', 13 should block or scatter no more than 20% of visible light, meaning that 80% of incident photons in the visible spectrum can pass through the film without being absorbed or deflected. At λ = 555 nm, the transmittance (T%) must be greater than 80%. The wavelength of light at 555 nm corresponds to the peak sensitivity of human vision; therefore, the T% at this specific wavelength is particularly relevant to our target application.

[0061] In practice, we can achieve the following results:

[0062] - Nanofiber layer 11 with nanofibers of 50 nm diameter: T% > 90

[0063] - Support layer with microfibers of 1μm to 2μm diameter 12: T% > 80

[0064] - Patterned layer 13 as a woven commercial polymer web: T% = 70 before modification, T% = 80 after modification by hot pressing.

[0065] The final transmittance of the overall or total multilayer textile 1, 1', 1”, 1”' is given by the product of the individual layers. By selectively melting the fibers in some regions to obtain the solid domain Ds, we can achieve a transmittance value greater than that given by the sum of the individual components 11, 11', 12, 12', 13.

[0066] The size of the pattern islands of the patterned islands of the patterned layer 13 or the patterned islands of the patterned layer 13 of the electrospinning device collector, and the lateral width of the subsequent solid domain Ds, can vary at their maximum point between 1m and 10nm, preferably between 1mm and 1μm, and more preferably between 100μm and 10μm.

[0067] Pattern islands with a maximum size of less than 100 μm have the advantage of being almost invisible to the naked eye, thus producing multilayer textiles 1 with a homogeneous appearance. The pattern islands can be placed in regular or irregular patterns. The pattern can be homogeneous through the multilayer textile 1, or it can present a gradient of pattern island concentration to impart specific characteristics to different areas of the multilayer textile 1 or subsequently the face mask.

[0068] The total pattern islands and the resulting solid domain Ds surface should account for between 5% and 95% of the total surface of the multilayer textile 1, preferably between 15% and 85%, and more preferably between 30% and 70%.

[0069] The thickness of the dense polymer region of the solid domain Ds and the film composition can be adjusted. The thickness of the solid domain Ds can vary between 100 nm and 0.1 cm, preferably between 1 μm and 1 mm, and more preferably between 10 μm and 100 μm.

[0070] 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 as filter membranes in filtration applications or as packaging materials.

[0071] Using chitosan-polycaprolactone blends for nanofiber layer 11 and / or support layer 12 is most preferred. Chitosan is largely available, biodegradable, renewable, and can be extracted from various biomass sources. Chitosan is non-cytotoxic, possesses inherent antimicrobial properties, and is electrospinnable. Furthermore, its unique molecular structure, characterized by a large number of polar amino groups, promises to improve filtration efficiency. Polycaprolactone is also highly biocompatible and biodegradable. The chitosan-based functional multilayer textile 1 is highly transparent (T>90%), and the reduced pore size is associated with promising filtration properties.

[0072] The main limitation lies in the mechanical stability of these small fibers; therefore, we sought larger supporting fibers for support layer 12. The supporting fibers we developed are based on polylactic acid (PLA), polyurethane, and their blends. These supporting fibers possess sufficient mechanical properties, low crystallinity, and large diameter to minimize light scattering. Interestingly, both polymers are biodegradable. PLA is produced entirely from the renewable raw material starch, while polyurethane is synthesized using both fossil and renewable raw materials. In summary, our developed formulation allows us to control the fiber size, as well as their surface chemistry and crystallinity.

[0073] By controlling these key parameters, we enhanced / balanced transparency, mechanical properties, and filtration efficiency. All polymers are biodegradable, so the final product will have a limited environmental impact if disposed of in landfills or dispersed into the environment (e.g., no persistent microplastics will be generated). Furthermore, most raw materials are also produced from renewable resources, potentially, but not automatically, reducing the carbon footprint.

[0074] Applying well-known principles of polymer chemistry and engineering, similar practical results can be obtained using many different polymers or combinations of polymers. In fact, any polymer or combination of polymers that can be molded into transparent films and / or fibers can be used. To optimize the properties of the material, it is also convenient to use suitable additives (curing agents, plasticizers, surfactants, clarifying agents, etc.), which can constitute up to 30% of the weight of the raw materials.

[0075] Polymers suitable for membrane and fiber production may include:

[0076] - Polyolefins: LDPE, HDPE, PP, PS, PAN, PVC, ...

[0077] - Polyesters: PET, PLA, PCL, PHA, PHB, ...

[0078] - Polycarbonate: PC, ...

[0079] - Polyethers: PEG, PEO, ...

[0080] - Polyamides, polyimides, aromatic polyamides: PA (e.g., nylon), PI, PAr (e.g., Kevlar), ...

[0081] - Polyurethane: PU, TPU, ...

[0082] -Silicone polymers: PDMS, ...

[0083] -A wide variety of polymers: PVA, PVP, PMMA, PVAc, ...

[0084] - Cellulose and its derivatives: ethyl cellulose, methyl cellulose, cellulose acetate, ...

[0085] Other natural polymers: hemicellulose, chitin, chitosan, starch, collagen (gelatin), ...

[0086] Using biocompatible, biodegradable, and antimicrobial thermoplastic polymers for the different layers 11, 12, 12', and 13 is most advantageous.

[0087] The polymer blends used for the different layers 11, 11', 12, 12', and 13 are composed of at least one thermoplastic, thermosetting, elastic, or thermoplastic elastomer polymer. More than one polymer can be used to form blends and composites to deduce the desired final properties of the textile.

[0088] Two or more different fibers may exist in the nanofiber layer 11, the support layers 12, 12', and / or the patterned layer 13, in more than one monolayer, produced by electrospinning. Therefore, the remaining production methods described above can be used. The formation of the solid domain Ds is the most important feature.

[0089] The masks disclosed herein are sanitary masks, face shields, surgical masks, or operating masks used in various applications. Furthermore, for aesthetic reasons, protective clothing may be transparent. Surgical drapes should be transparent to allow for better patient monitoring.

[0090] Another application is as a window screen, semi-transparent window screen, or anti-smog window screen that filters fine particulate matter (PM 2.5, PM 10).

[0091] These composite multilayer textiles can also be used as encapsulation materials, serving as highly breathable, permeable, semi-transparent films for specific encapsulation applications. These composite multilayer textiles block aerosol droplets, pollen, bacteria, and spores, but allow the product to be seen and permit very high transpiration.

[0092] Technicians understand the setup used to determine optical transparency. Here, transparency is quantified by measuring transmittance using a UV-Vis spectrophotometer from Agilent, the "Cary 4000". Typically, a 1cm... 2 The solid sample holder (Agilent) of the aperture hood positions the sample orthogonally to the incident light. Of course, simulation measurements can be performed using a conventional spectrometer with an aperture hood of up to several square centimeters that operates within the wavelength range of interest.

[0093] In fact, the transparent filter 1 mainly consists of two parts: an electrospun nanofiber pad 11 as the filter element, and a support material made of commercially available PLA mesh 12. To increase the transparency of the final product, the PLA mesh is pressed at 120°C and subjected to a pressure of 50 bar for 30 seconds.

[0094] The original PLA web possesses inherent antistatic properties, preventing fiber deposition during the electrospinning process. Therefore, a skin-compatible surfactant (TWEEN 80) was selected as the antistatic agent to coat the web using a dip-coating technique with a 1.0 wt% ethanol solution. Subsequently, a thin layer of polyamide-11 (PA11) electrospun nanofibers (approximately 0.1 g / m²) was directly coated onto the prepared substrate (pressed PLA + TWEEN 80) using Elmarco's pilot-scale electrospinning equipment, the "Nanospider." 2 A 6% by weight solution of anisole formic acid was used to obtain fibers with an average diameter of 72 ± 29 nm.

[0095] Use domestically produced settings to measure filtration efficiency, such as Figure 3a As depicted. Used in each test:

[0096] A circular sample with a diameter of 46 mm; an aerosol composed of neutral sugar particles with a diameter ranging from 20 nm to 2000 nm;

[0097] A pump system that generates a constant gas flow rate of 8 L / min (air velocity of 8 cm / s) through the sample;

[0098] The Cambustion DMS500 particle analyzer measures the concentration of aerosols diffused through a sample in real time. Particle filtration efficiency is given as a percentage and is determined by comparing aerosol concentrations with and without a filtration system after steady-state particle flow is reached (approximately 3 minutes later).

[0099] The transparent composite nanofiber-based multilayer textile 1PLA-PA11 system exhibits good filtration efficiency for neutralized fructose particle aerosols, with a filtration efficiency of >90% for a 1 μm flow-through particle size.

[0100] Breathability was evaluated according to EN-14683:2019 medical face mask standard. Breathability was related to the pressure drop of the test material measured by applying a flow rate of 27 cm / s. The transparent composite nanofiber-based multilayer textile 1PLA-PA11 filter showed a pressure drop of 9 Pa / cm. 2 The pressure drop (according to EN-14683:2019, the limit for Type I and Type II medical masks is 40 Pa / cm) 2 ).

[0101] Transparency was quantified by measuring the transmittance of the filter using a UV-Vis spectrophotometer "Cary 4000" from Agilent. A 1cm... 2 The solid sample holder (Agilent) of the aperture hood positions the sample orthogonally to the incident light. Assuming 100% transmittance in air, in our example, the transparent composite nanofiber-based multilayer textile 1PLA-PA11 filter exhibits 76% transmittance at λ = 555 nm (the visible light span is from approximately 400 nm to 800 nm). The image below shows the transparent composite nanofiber-based multilayer textile 1PLA-PA11 sample. Figure 3b The ultraviolet-visible spectrum in [the text].

[0102] List of reference numerals

[0103] 0 Production Setup

[0104] 1 Transparent composite nanofiber-based multilayer textiles / films

[0105] 11 Nanofiber layers (diameter less than 100 nm)

[0106] 12,12' has a support layer with microfibers (diameter of 1 to 2 micrometers).

[0107] 13 Patterned layers / porous substrate layers (woven / melt-spun, melt-blown / foil with openings)

[0108] 130 pattern

[0109] 2. Belt (the collector of the electrospinning equipment can form part of the belt)

[0110] 3. Press / calender

[0111] 30 pressure rollers

[0112] 4 rollers (for multi-layer textiles)

[0113] I. Electrospinning Steps

[0114] II. Thermomechanical treatment steps (T1, p1)

[0115] III. Cooling Steps (T2, pat)

[0116] Ds solid domain (lateral thickness between 1 μm and 100 μm, lateral width between 10 μm and 100 μm)

Claims

1. A composite multilayer textile (1), comprising: The composite multilayer textile (1) comprises at least one nanofiber layer (11) having nanofibers with a diameter less than 100 nm, and a support layer (12) having microfibers with a diameter less than 5 micrometers, wherein the nanofiber layer (11) and the support layer (12) are produced by electrospinning, and the composite multilayer textile (1) exhibits a total transmittance (T%) greater than 50% at λ = 555 nm. Its features are, The at least one nanofiber layer (11) and the support layer (12) are fused at the closed regions of the pattern used in the production process, thereby forming solid domains (Ds) in the composite multilayer textile (1), wherein the solid domains (Ds) are separated or connected to each other, exhibiting a defined shape with a regular or irregular spatial distribution, and the fibrous morphology of the nanofibers of the nanofiber layer (11) and the microfibers of the support layer (12) is preserved on top of the open regions next to the solid domains (Ds), thereby achieving a total transmittance of the entire composite multilayer textile (1) that is greater than that given by the sum of the individual nanofiber layers (11) and the support layer (12).

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

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 exhibits a solid domain (Ds) at the fusion location of all three layers (11, 12, 12').

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

5. The composite multilayer textile (1) according to claim 4, wherein the solid domain (Ds) is formed as a contact area, the contact area connecting the nanofiber layer (11, 11'), the support layer (12, 12') and the patterned layer (13), exhibiting a thickness between 1 μm and 100 μm.

6. The composite multilayer textile (1) according to claim 4, wherein the solid domain (Ds) is formed as a contact region connecting the nanofiber layer (11, 11') and the support layer (12, 12'), exhibiting a thickness between 1 μm and 100 μm.

7. The composite multilayer textile (1) according to any one of claims 1-4, wherein the solid domain (Ds) exhibits a maximum lateral width between 10 μm and 100 μm at its widest point.

8. The composite multilayer textile (1) according to any one of claims 1-4, wherein the pattern of the solid domains (Ds) on the composite multilayer textile (1) has a value between 30% and 70% of the total surface area of ​​the composite multilayer textile (1).

9. The composite multilayer textile (1) according to any one of claims 2 and 4, wherein the transverse thickness of the patterned layer (13) varies between 1 μm and 100 μm, and the patterned layer (13) is formed of a woven polymer web.

10. The composite multilayer textile (1) according to any one of claims 2 and 4, wherein the transverse thickness of the patterned layer (13) varies between 1 μm and 100 μm, and the patterned layer is formed of a thermoplastic material having a plurality of through holes as openings and a mesh structure as connecting webs, wherein at least 30% of the total surface area of ​​the thermoplastic material is open.

11. The composite multilayer textile (1) according to claim 4, wherein the nanofiber layers (11, 11') comprise chitosan / polycaprolactone nanofibers, and the support layers (12, 12') comprise polyester / polyurethane microfibers.

12. The use of the composite multilayer textile (1) according to any one of claims 1 to 11 as part of a face shield for use in medical devices and / or personal protective equipment.

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