Method and apparatus for manufacturing electrostatic electret fibers and electret products

Abstract

The invention relates to a method for producing electrostatically charged fibres, in particular for producing electret fibre formations, in which method fibres are produced from synthetic and / or natural materials, a polar liquid is atomised by means of a gaseous pressure medium to produce a treatment aerosol, the fibres are treated with the treatment aerosol for electrostatic charging, wherein the atomisation is carried out at a polar liquid volume flow in litres per hour to the overpressure of the gaseous pressure medium in millibar of 0.004 to 0.008.

Description

Technical Field

[0001] This invention relates to a method for manufacturing electrostatic electret fibers—particularly electrostatic electret fibers for manufacturing electret fiber formations / fiber structures. Furthermore, this invention relates to an apparatus for manufacturing electrostatic electret fibers—particularly electrostatic electret fibers for manufacturing electret fiber formations. Finally, this invention relates to an electret product, particularly electret fibers and / or electret fiber nonwoven fabrics. Background Technology

[0002] So-called water electret can electrostatically apply charge / electrostatic electret to fibers or formations made from such fibers. This electrostatic electret can, for example, benefit the filtration performance of the fiber formation. In so-called water electret, aerosols and / or vapors are generated by a polar liquid and released under defined operating conditions, the charge deposited on the fibrous material, such as nonwoven fabric or fibers made of polymer. The charge can be semi-permanently anchored to the corresponding fiber surface by additives and thus improve the filtration efficiency of such fibrous material.

[0003] However, water electreting results in the wetting of the corresponding fibers or fiber formations. In subsequent processing steps, this wetting can lead to corrosion and mold growth. To avoid these consequences, active drying of the fibers or fiber formations is implemented. However, this active drying increases manufacturing costs and the complexity of the production facilities used for it. Furthermore, active drying involves higher energy requirements, which additionally increase manufacturing costs. Summary of the Invention

[0004] Against the backdrop described above, the object of this invention is to provide a method for manufacturing electrostatic electret fibers, which can be implemented with lower manufacturing costs and energy consumption while achieving high operational safety and high product quality. The object of this invention also is to provide an apparatus for manufacturing electrostatic electret fibers and an electret product.

[0005] This objective is achieved by the method for manufacturing electrostatic electret fibers, the equipment for manufacturing electrostatic electret fibers, and the electret product, as described below.

[0006] A first aspect of the invention relates to a method for manufacturing electrostatic electret fibers, particularly electret fiber formations, in which fibers are manufactured from synthetic and / or natural materials, a polar liquid is atomized by means of a gaseous pressure medium to generate a treatment aerosol, and the fibers are treated with the treatment aerosol for electrostatic electret. According to the invention, atomization is performed when the quotient of the polar liquid volumetric flow rate (in liters per hour) and the overpressure of the gaseous pressure medium (in millibars) is 0.004 to 0.008.

[0007] Therefore, according to the present invention, atomization is performed at a ratio of 0.004 to 0.008 between the volumetric flow rate of the polar liquid (in liters per hour) and the overpressure of the gaseous pressure medium (in millibars).

[0008] By employing this quotient or ratio, a relatively large amount of charge can be generated and applied to the corresponding fibers. Simultaneously, this quotient or ratio can effectively limit or minimize the amount of processed aerosol produced. In this way, it is ensured that only a relatively small amount of the fiber or fiber formation is wetted. Therefore, active drying of the electrostatically electret fibers can be avoided, thereby significantly reducing manufacturing costs and the energy consumption required for manufacturing. At the same time, due to sufficient electrostatic electret, a high filtering effect is guaranteed in the fiber formation manufactured from the fibers produced in this way.

[0009] Preferably, the overpressure of the gaseous pressure medium can be an overpressure relative to ambient pressure. Therefore, the overpressure of the gaseous pressure medium can be related to the pressure difference between the gaseous pressure medium and ambient pressure. By using overpressure relative to ambient pressure, atomization can be achieved in a particularly advantageous manner and with high operational safety.

[0010] Overpressure of a gaseous pressure medium can also be absolute pressure. Absolute pressure is understood as pressure relative to a zero reference pressure, that is, the pressure existing in a vacuum or a space without air.

[0011] In a preferred manner, the fibers can be made of any fusible and / or soluble material, or have fusible and / or soluble materials. Particularly preferred is the use of a polymer melt. The polymer melt can, in particular, contain polypropylene (PP), polycarbonate (PC), polyamide (PA), polyethylene (PE), polylactic acid (PLA), polyvinylidene fluoride (PVDF), or mixtures of these polymers.

[0012] According to a preferred embodiment of the method according to the invention, atomization can be performed when the quotient of the polar liquid volumetric flow rate (in liters per hour) and the overpressure (in millibars) of the gaseous pressure medium is 0.005 to 0.007, particularly 0.006 or about 0.006. In this way, electrostatic electret can be achieved with particularly high safety while requiring very little humidification of the fibers.

[0013] Another aspect of the invention relates to a method for manufacturing electrostatic electret fibers, particularly for manufacturing electret fiber formations, in which fibers are manufactured from synthetic and / or natural materials, a polar liquid is atomized by means of a gaseous pressure medium to generate a treatment aerosol, and the fibers are treated with the treatment aerosol for electrostatic electret, wherein atomization is performed when the quotient of the mass flow rate of the polar liquid and the mass flow rate of the gaseous pressure medium is 1.4 to 3.

[0014] By employing this quotient or ratio, a relatively large amount of charge can be generated and applied to the corresponding fibers. Simultaneously, by employing this quotient or ratio, the amount of processed aerosol generated can be sufficiently limited or kept to a very small level. This ensures that only a relatively small amount of the fiber or fiber formation is wetted. Therefore, active drying of the electrostatically electret fibers can be avoided, thereby significantly reducing manufacturing costs and the energy consumption required for manufacturing. Ultimately, due to sufficient electrostatic electret, a high filtering effect is guaranteed in the fiber formation manufactured from the fibers thus produced.

[0015] The aforementioned other aspect of the invention can be implemented as an addition to or alternative to the first aspect of the invention as previously described. That is, atomization can be performed not only as a quotient of 0.004 to 0.008 of the polar liquid volumetric flow rate (in liters per hour) and the overpressure (in millibars) of the gaseous pressure medium, but also as a quotient of 1.4 to 3 of the polar liquid mass flow rate and the gaseous pressure medium mass flow rate. Similarly, according to the invention, atomization can also be performed using only one of these quotients.

[0016] According to an advantageous design, atomization can be performed when the quotient of the mass flow rate of the polar liquid to the mass flow rate of the gaseous pressure medium is 1.5 to 2.9, especially 2 to 2.5. In this way, electrostatic electret can be achieved with a particularly high degree of safety while requiring minimal humidification of the fibers.

[0017] Another aspect of the invention relates to a method for manufacturing electrostatic electret fibers, particularly for manufacturing electret fiber formations, in which fibers are manufactured from synthetic and / or natural materials, a polar liquid is atomized by means of a gaseous pressure medium to generate a treatment aerosol, and the fibers are treated with the treatment aerosol for electrostatic electret, wherein atomization is performed when the quotient of the volumetric flow rate of the polar liquid and the volumetric flow rate of the gaseous pressure medium is 0.001 to 0.004.

[0018] By employing the aforementioned quotient or ratio, a suitable amount of charge can be generated and applied to the corresponding fibers. Simultaneously, by employing this quotient or ratio, the amount of processed aerosol generated can be sufficiently limited or kept to a very small level. Thus, it is advantageously ensured that only a relatively small amount of moisture is applied to the fibers or fiber formations. This avoids the need for active drying of the electrostatically electret fibers, thereby significantly reducing manufacturing costs and the energy consumption required for manufacturing. Due to the sufficient electrostatic electret achieved in this way, high filtering performance can be guaranteed for the fiber formations manufactured from the fibers thus produced.

[0019] Another aspect of the invention described above can be implemented as an addition to or alternative to the aspects of the invention described above. That is, atomization can be performed not only at a ratio of 0.001 to 0.004 of the volumetric flow rate of the polar liquid to the volumetric flow rate of the gaseous pressure medium, but also simultaneously at a ratio of 0.004 to 0.008 of the volumetric flow rate of the polar liquid (in liters per hour) to the overpressure (in millibars) of the gaseous pressure medium and / or at a ratio of 1.4 to 3 of the mass flow rate of the polar liquid to the mass flow rate of the gaseous pressure medium. Similarly, according to the invention, atomization can also be performed using only one of these quotients.

[0020] When referring to electrostatic electret fibers, they can specifically refer to so-called electret fibers. Electret fiber formations can specifically refer to electret fiber nonwovens.

[0021] Electrets can be understood here as semi-permanent or permanent electrostatic electret products, such as electrostatic electret filter nonwoven fabrics.

[0022] In a preferred manner, the nozzle device can be configured to generate a treatment aerosol by atomizing a polar liquid with the aid of a gaseous pressure medium, wherein the average droplet size of the treatment aerosol thus generated can be <100 μm.

[0023] According to a preferred design, atomization can be performed under environmental conditions where the ambient temperature is between 0°C and 30°C, particularly between 15°C and 25°C, or between 20°C and 25°C. Furthermore, according to a preferred design, atomization is performed at an ambient pressure of 900 mbar to 1100 mbar, particularly around 1000 mbar, or around 1013.25 mbar. These operating conditions can be maintained with relatively low costs and ensure reproducible product quality.

[0024] In another preferred manner, polar liquids can be atomized using at least one two-component nozzle, and in particular, multiple two-component nozzles. Two-component nozzles achieve particularly reliable and uniform liquid atomization, thereby ensuring high overall operational safety. In a particularly advantageous manner, such two-component nozzles can be configured as flat-jet nozzles / fan nozzles, whereby the generated aerosol can be spatially distributed in a suitable manner.

[0025] According to another preferred design, atomization in a two-component nozzle or in each two-component nozzle can be carried out at a polar liquid volumetric flow rate of 3.2 liters / hour to 5.2 liters / hour, particularly 4.2 liters / hour or about 4.2 liters / hour. This volumetric flow rate allows for atomization in a suitable manner using a two-component nozzle, while simultaneously ensuring sufficient electrostatic loading of the corresponding fibers to be loaded.

[0026] In another preferred manner, atomization in a two-component nozzle or in each two-component nozzle can be carried out at a polar liquid mass flow rate of 3.2 kg / h to 5.2 kg / h, particularly 4.2 kg / h or about 4.2 kg / h. Similarly, this mass flow rate allows for suitable atomization using a two-component nozzle while simultaneously ensuring sufficient electrostatic loading of the corresponding fiber to be loaded.

[0027] Alternatively, polar liquids can be atomized under an overpressure of 500 mbar to 900 mbar in the gaseous pressure medium, particularly under an overpressure of 700 mbar or about 700 mbar. This overpressure of the gaseous pressure medium reliably ensures atomization of the polar liquid, especially at the aforementioned specified volumetric flow rate and / or mass flow rate of the polar liquid in each two-component nozzle. This further improves operational safety.

[0028] In another preferred manner, atomization in a two-component nozzle, or in each two-component nozzle, can be achieved at a mass flow rate of 2.1 kg / h to 2.7 kg / h for a gaseous pressurized medium, particularly at a mass flow rate of 2.1 kg / h to 2.5 kg / h or 2.3 kg / h to 2.7 kg / h for a polar liquid. Especially at the aforementioned specified volumetric and / or mass flow rates of the polar liquid in each two-component nozzle, this mass flow rate of the gaseous pressurized medium in each two-component nozzle can be provided with minimal cost while simultaneously ensuring reliable atomization of the polar liquid. This approach further improves operational safety.

[0029] Additionally or alternatively, atomization in one or each of the two-component nozzles can be carried out at a volumetric flow rate of 1.5 m³ / h to 2.5 m³ / h of gaseous pressurized medium, particularly at a volumetric flow rate of 1.8 m³ / h to 2.1 m³ / h. Simultaneously, atomization in one or each of the two-component nozzles can be carried out at a volumetric flow rate of polar liquid from 0.002 m³ / h to 0.008 m³ / h. Reliable atomization of the polar liquid can be ensured by using this volumetric flow rate of gaseous pressurized medium and / or polar liquid in each two-component nozzle, particularly at the above-specified volumetric flow rate and / or mass flow rate of polar liquid in each two-component nozzle. This method can further improve operational safety.

[0030] More preferably, water can be used as the polar liquid. Even more preferably, a compressible gas, preferably air, and / or a gas containing air can be used as the gaseous pressure medium. Polar liquids in the form of water or air as the gaseous pressure medium can be provided at very low cost and are suitable for generating treatment aerosols for fiber electrostatic electretting.

[0031] More preferably, the fibers can be treated or sprayed with a treatment aerosol before being integrated into a fibrous nonwoven fabric and / or laid on a collection device, particularly a laying belt. Similarly, the fibers can be treated or sprayed with a treatment aerosol before being trapped by a vacuum source. This spraying can be done directly through a corresponding two-component nozzle.

[0032] The fibers treated with the aerosol can be thoroughly dried by laying them on a collection device, a laying belt, or by capturing them with the aid of a vacuum source, thus eliminating the need for additional or separate active drying.

[0033] In an even more preferred manner, fibers can be manufactured via a meltblown process. Here, the fibers can be treated or sprayed directly after exiting the meltblown nozzle assembly using a treatment aerosol. The treatment aerosol can be fed into the outlet nozzle of the meltblown nozzle assembly via a suitable two-component nozzle for spraying or treating the fibers. This ensures particularly reliable process control for the electrostatic electret of the corresponding fibers.

[0034] According to another preferred design, the fibers can be integrated into a nonwoven fabric and / or laid on a collection device, particularly a laying belt, after being sprayed with the processing aerosol. Therefore, the processing or spraying of the fibers with the processing aerosol can be performed between the fibers leaving the corresponding nozzle device and being laid on the collection device or captured by a vacuum device. Thus, the integrated fibers are sufficiently electrostatically electretted at the moment of laying or capturing.

[0035] More preferably, the fibers integrated into fiber-formed products and / or fiber nonwovens and / or laid on the collection device, especially the laying belt, can have a residual moisture content of less than 6%, especially less than 5%, without being actively dried. In this way, the use of additional devices to actively dry the fibers or integrated fiber-formed products and / or fiber nonwovens can be avoided, thereby keeping the equipment costs for carrying out the method very low.

[0036] In a preferred manner, this method enables the production of electrostatic electret fibers laid on a collection device with very low residual moisture. Therefore, additional active drying by means of an auxiliary drying device can be avoided. Simple suction at the collection device or at the laying strip can also adequately dry the laid fiber-formed or nonwoven fabric without the need for a separate drying device.

[0037] The collection device can be configured as a layup belt, particularly a bottom-suction conveyor belt, a bottom-suction layup screen and / or layup grid, and / or a conductive layup grid. Bottom suction ensures the separation of previously introduced media, such as air and / or water, from the laid-up fiber formation, particularly the fibrous nonwoven fabric. In so-called electrospinning, the layup grid can also be configured to be conductive.

[0038] In another preferred manner, for the manufacture of fibers, at least one additive or combination of additives for stabilizing charge can be used. Examples of such additives include fatty acids, especially distearate ethylenediamine and / or its salts, preferably magnesium stearate, sterically hindered amines, preferably Chimmasorb 944, fluorinated compounds and / or polymers and / or combinations thereof. In this way, the electrostatic electret of the fibers can be maintained with high safety, thereby maintaining the performance of the manufactured products, especially electret products, with high safety and over a relatively long period of time.

[0039] In an even more preferred manner, the polar liquid may contain at least one additive for improving charge application, the long-lasting effect of electrostatic charge, and / or filtration, and / or for semi-permanent charge application. Fibers treated with such a liquid or the resulting aerosol can guarantee particularly advantageous performance, especially in terms of the degree of electret formation and the long-lasting effect of electret formation. Fiber-formed fabrics or nonwoven fabrics made from such treated fibers have particularly advantageous filtration power, which is also maintained over long periods of time.

[0040] Another aspect of the invention relates to an apparatus for manufacturing electrostatic electret fibers and / or for manufacturing electret fibers and / or electret fiber nonwoven fabrics, wherein the electrostatic electret fibers are particularly used for manufacturing electret fiber formations. Such an apparatus is particularly suitable for performing the methods described above.

[0041] The apparatus according to the invention is equipped with a spinning device for manufacturing fibers from synthetic and / or natural materials and / or with a nozzle device for generating a treatment aerosol by atomization of a polar liquid using a gaseous pressure medium and for electrostatic electreting of the fibers by spraying the treatment aerosol onto the fibers. Now, according to the invention, the nozzle device is configured to atomize at a ratio of 0.004 to 0.008 of the polar liquid volumetric flow rate (in liters per hour) to the overpressure of the gaseous pressure medium (in millibars), and / or at a ratio of 1.4 to 3 of the polar liquid mass flow rate to the gaseous pressure medium mass flow rate, and / or at a ratio of 0.001 to 0.004 of the polar liquid volumetric flow rate to the gaseous pressure medium volumetric flow rate.

[0042] This device allows for the generation and application of a relatively large amount of charge onto the resulting fibers. Simultaneously, the amount of processed aerosol generated can be effectively limited or kept to a very small level through this ratio. This ensures that only a relatively small amount of moisture is applied to the fibers or fiber formations. Therefore, active drying of the electrostatically electret fibers can be avoided, thereby significantly reducing equipment costs and the energy consumption required for manufacturing. Furthermore, the ample electrostatic electret ensures high filtering performance of the fibers or fiber formations manufactured using this device.

[0043] In a preferred manner, the melt can exit from the spinning device during operation of such equipment, and the melt can be drawn by process air. This generates what is known as a free jet. A free jet is a flow of fibers consisting of air and, for example, polymer monofilaments. Preferably, fiber-formed products or nonwoven fabrics can be generated from this free jet at a collecting device, where a portion of the air and aerosol can be extracted and processed.

[0044] More preferably, electrostatic charge is applied only to a defined portion of the fibers in the free jet, while some or a portion of the fibers are not subjected to electrostatic charge application. The electrostatic charge application to the corresponding fibers can continue until charge saturation.

[0045] According to a preferred design of the equipment, the nozzle device may have one or more bicomponent nozzles, wherein the multiple bicomponent nozzles are preferably arranged at a spacing of 4 cm to 10 cm, particularly 5 cm to 8 cm, or 7 cm or about 7 cm between each other. In this way, fibers from multiple capillaries of the melt spinning device or meltblown nozzle device can be processed in a suitable manner or uniformly.

[0046] More preferably, the openings of the two-component nozzles can be arranged at an angle relative to the horizontal line, particularly an angle of 1° to 30°, preferably 5° to 20°. This arrangement can produce a relatively well-distributed aerosol mist and thus treat the fibers particularly uniformly.

[0047] According to another preferred design, the spinning apparatus can be configured as a melt-blowing apparatus, a melt-spinning apparatus, particularly a melt-spinning apparatus with Exxon nozzles or one or more rows of coaxial nozzles or nonwoven fabric nozzles, or a solvent spinning apparatus / solution spinning apparatus. Therefore, the nozzle device according to the invention can be used with different types of spinning apparatuses, or in different methods, such as in melt spinning, melt-blowing, and / or solvent spinning.

[0048] When performing the meltblown method, the free jet velocity or filament velocity can be referred to as the "impact velocity / whipping velocity". This impact velocity can be given, for example, by the throughput / flow rate (number of holes per inch) per unit capillary orifice in the corresponding spinning device.

[0049] Preferably, in the meltblown method, the material throughput of the spinning device can be in the range of 0.5 kg / h / m to 100 kg / h / m, where the length in meters should be referred to as the device width or device length. Multiple capillary orifices can be provided along the device width or device length. That is, the exemplary range of 0.5 kg / h / m to 100 kg / h / m can be derived from the number of capillaries in the corresponding spinning device (Exxon nozzles and / or coaxial nozzles).

[0050] For example, a spinning device with a total of 1968 capillary orifices per meter can be used in the melt-blowing method. Therefore, the melt throughput per capillary orifice can be calculated from the throughput of a corresponding melt delivery pump with a capacity of 30 kg / h / m, as follows:

[0051] 30 kg / h / m / 1968 capillary pores / m = 0.015 kg / h / capillary pores

[0052] In a particularly preferred manner, in the case where the throughput of the melt transfer pump is in the range of 10-50 kg / h / m and the spinning device with meltblown nozzles has about 1500-2500 capillary orifices / m, a throughput of 0.0066 kg / h to 0.2 kg / h per capillary orifice can be produced.

[0053] In a preferred design of this method and / or this apparatus, each capillary orifice of the corresponding spinning device can produce a material throughput of 0.0066 kg / h to 0.2 kg / h.

[0054] More preferably, in the nonwoven fabric spinning method, the material throughput of the spinning device can be in the range of 1 kg / h / m to 400 kg / h / m.

[0055] More preferably, in solvent spinning, the material throughput of the spinning apparatus can be in the range of 0.001 kg / h / m to 20 kg / h / m.

[0056] By means of the method or apparatus according to the invention, an electrostatic charge can be applied to each suitable fiber material or filter material, thereby improving its filtration performance.

[0057] Finally, another aspect of the invention relates to an electret product, particularly electret fibers and / or electret fiber nonwovens, which can be manufactured according to the methods described above and / or by the equipment described above. The electret product can be, in particular, a semi-permanent or permanent electrostatic electret product.

[0058] Such electret products, especially such electret fiber nonwovens or electret fiber formations, can have high quality factors (Q factors), such as Q factors of 10-20, and particularly preferably 14-17. The Q factor indicates the filtering effect or filtering power of the corresponding product. For example, for applications in gas masks, the Q factor is an important quality characteristic.

[0059] The Q factor is also used to compare the filtration power of different nonwoven fabrics. The Q factor is calculated from the quotient of permeability and pressure loss using the following formula:

[0060]

[0061] Permeability is expressed as ln(1 / (permeability / 100)), and pressure loss is given in the placeholder "pressure drop", preferably in millibars.

[0062] The Q factor is also related to the measuring device used. Preferably, the Q factor is determined using a TSI 8130 measuring device from TSI Corporation with a 2% NaCl (sodium chloride) solution and a volumetric flow rate of 48 liters per minute.

[0063] The preferred design and advantages described above regarding the method for manufacturing electrostatic electret fibers are equally applicable to the equipment described above for manufacturing electrostatic electret fibers and also to the electret products described above. Attached Figure Description

[0064] The invention will now be described exemplarily with reference to the accompanying drawings. Specifically:

[0065] Figure 1A cross-sectional view of a device according to an embodiment of the present invention is shown.

[0066] Figure 2 A cross-sectional view of a device according to another embodiment of the present invention is shown.

[0067] Figure 3 A cross-sectional view of the device according to another embodiment of the invention is shown.

[0068] Figure 4 A cross-sectional view of the device according to another embodiment of the invention is shown.

[0069] Figure 5 A side view of the nozzle assembly of the apparatus according to the invention for manufacturing electrostatic electret fibers is shown. Detailed Implementation

[0070] Figure 1 A cross-sectional view of an apparatus 10 according to an embodiment of the present invention is shown. The apparatus 10 is configured for manufacturing electrostatic electret fibers 12, which are particularly used for manufacturing electret fiber formations 14.

[0071] according to Figure 1 The apparatus 10 in the embodiment has a spinning device 16 for manufacturing fibers from polymer material 18. According to Figure 1 The spinning device 16 can be configured as a meltblown device, and for this purpose has a meltblown nozzle device 20. The meltblown nozzle device 20 can be, in particular, a so-called Exxon nozzle.

[0072] Therefore, equipment 10 can be a meltblown fabrication facility.

[0073] Within the meltblown nozzle device 20, the polymer material 18 may exist as a polymer melt or be introduced into the meltblown nozzle device 20 as a polymer melt.

[0074] In addition, according to Figure 1 The device 10 has a nozzle assembly 22 for generating a treatment aerosol 24 by means of a gaseous pressure medium through the atomization of a polar liquid. The nozzle assembly 22 is designed to apply an electrostatic charge to the fibers by spraying the treatment aerosol 24 onto them.

[0075] Here, the nozzle device 22 is configured to atomize the polar liquid at a volumetric flow rate of 3.2 to 5.2 liters per hour, with the overpressure of the gaseous pressure medium (in millibars) being 0.004 to 0.008. Alternatively or additionally, the nozzle device 22 may be configured to atomize the polar liquid at a mass flow rate that is 1.4 to 3 times the mass flow rate of the gaseous pressure medium. Similarly, the nozzle device 22 may be configured to atomize the polar liquid at a volumetric flow rate that is 0.001 to 0.004 times the volumetric flow rate of the gaseous pressure medium.

[0076] By using this ratio, a relatively large amount of charge can be generated and applied to the fibers. By using this ratio, the amount of processed aerosol 24 produced can also be sufficiently limited or kept very small. In this way, it is ensured that only a relatively small amount of the fibers or fiber formation 14 is wetted. Therefore, active drying of the electret fibers 12 or fiber formation 14 can be avoided, thereby reducing manufacturing costs and the energy consumption required for manufacturing. At the same time, due to sufficient electrostatic electreting, a high filtration efficiency is ensured for the fiber formation 14 produced from the electrostatic electret fibers 12 thus manufactured.

[0077] according to Figure 1 The meltblown nozzle device 20 has at least one air passage 26 through which airflow is guided to the produced fiber, particularly acting tangentially on the fiber to stretch it.

[0078] After the fibers are treated with the processing aerosol 24, the electret fibers are laid out onto a collection device 28. The collection device 28 may be, for example, a laying strip. To lay or integrate the electret fibers 12 onto the collection device 28, a gas flow 30 may be used for suction or desiccation. The gas flow 30 may be provided by suction and / or desiccation devices not shown in detail herein. Through suction or desiccation and laying of the electret fibers 12, sufficient drying of the electret fibers 12 treated by the processing aerosol 24 can be achieved, as only limited wetting is performed by means of the nozzle device 22. By laying or integrating the electret fibers 12 onto the collection device 28, a fiber formation 14, such as a nonwoven fabric, can be produced.

[0079] Figure 2 A cross-sectional view of a device 10 according to another embodiment of the invention is shown. Figure 2 The device 10 is also configured for manufacturing electrostatic electret fibers 12, which are particularly used for manufacturing electret fiber formations 14.

[0080] according to Figure 2 The equipment 10 has a spinning device 16 for producing fibers from polymer material 18. According to... Figure 2Device 10 and according to Figure 1 The difference in equipment lies in the design of the spinning device 16. According to... Figure 2 The spinning apparatus 16 can be configured as a melt spinning apparatus and for this purpose has a melt spinning nozzle apparatus 21. The melt spinning nozzle apparatus 21 can, for example, have one or more rows of coaxial nozzles.

[0081] Therefore, according to Figure 2 The equipment 10 can be a melt spinning facility.

[0082] according to Figure 2 The spinning device 16 produces multiple rows of fiber slivers or fiber jets. The nozzle device 22 can be set or arranged so that all fibers or all rows of fibers are treated by the processing aerosol 24.

[0083] Figure 3 A cross-sectional view of a device 10 according to another embodiment of the invention is shown. According to... Figure 3 The device 10 is also configured for manufacturing electrostatic electret fibers 12, which are particularly used for manufacturing electret fiber formations 14.

[0084] exist Figure 3 Different embodiments of the device 10 are shown in the diagram. For example, a compression roller 56 (shown in solid lines) may be arranged in the conveying direction of the collecting device 28, or a sealing roller 56' (shown in dotted lines) may be arranged in the opposite direction to the conveying direction of the collecting device 28. In one embodiment, not only the compression roller 56 but also the sealing roller 56' may be provided. The compression roller 56 compresses the fiber formation, and the sealing roller has a sealing function.

[0085] according to Figure 3 The equipment 10 also has a spinning device 16 for producing fibers from the polymer material 18. Here, according to Figure 3 Device 10 and according to Figure 1 or Figure 2 The difference in equipment lies again in the design of the spinning device 16. According to... Figure 3 The spinning apparatus 16 can be configured as a melt spinning apparatus and for this purpose has a melt spinning nozzle device 21. The melt spinning nozzle device 21 can in particular have one or more rows of spunbond nonwoven fabric nozzles.

[0086] Therefore, according to Figure 3 The equipment 10 may be a melt spinning facility in which the fiber or monofilament is stretched after cooling, as will be further described below.

[0087] according to Figure 3The spinning device 16 produces multiple rows of fiber slivers or fiber jets. The nozzle device 22 can be set or arranged so that all fibers or all rows of fibers are treated by the processing aerosol 24.

[0088] Prior to treating the fibers with the processing aerosol 24, oligomer removal and / or spinning fume extraction 32 may optionally be performed by means of an extraction device not shown in detail herein.

[0089] After treatment with the aerosol 24 via the nozzle device 22, the electrostatic electret fiber 12 is then cooled 34, particularly by air cooling or so-called air quenching. For this purpose, a cooling device not shown in detail here can be used.

[0090] After cooling 34, the electret fiber 12 is then stretched by primary air 36 or stretching air. Primary air 36 or stretching air can be input through air inlet 38. In the subsequent travel of the electret fiber 12, alternatively, secondary air 40 is supplied to the electret fiber through air inlet 42 and tertiary air 44 is supplied through air inlet 44 (not shown in detail here).

[0091] Primary air is guided in the spinning channel 58 together with the electrostatic electret fiber 12. The spinning channel 58 may be circular and / or rectangular and may consist of continuous spinning channels 58 or spinning channel components spaced apart from each other.

[0092] After processing the fibers using the processing aerosol 24 and cooling 34, stretching by means of primary air 36 and optionally introducing secondary air 40 and tertiary air 44, the electrostatic electret fibers 12 can be laid or integrated onto the collection device 28, as already referred to above. Figure 1 As illustrated in the embodiments.

[0093] Figure 4 A cross-sectional view of a device 10 according to another embodiment of the invention is shown. According to... Figure 4 The equipment 10 is also used to manufacture electrostatic electret fibers 12, which are particularly used to manufacture electret fiber formations 14.

[0094] according to Figure 4 The equipment 10 also has a spinning device 16 for producing fibers from the polymer material 18. Here, according to Figure 4 Device 10 and according to Figure 1 , Figure 2 or Figure 3 The difference in equipment lies again in the design of the spinning device 16. Therefore, the solvent spinning device is constructed according to... Figure 4The spinning apparatus 16 may therefore have a solvent nozzle device 23. Polymer material 18 in the form of a polymer solution may be present in the solvent nozzle device 23.

[0095] Therefore, according to Figure 4 Equipment 10 can be a solvent spinning facility.

[0096] Before treating the fibers using processing aerosol 24, according to Figure 4 In one embodiment, the fibers can optionally be stretched using primary air 36 or stretching air. Primary air 36 or stretching air can be input via an air inlet not shown in detail here. Following optional stretching using primary air 36 or stretching air, the fibers are then treated with a processing aerosol 24 via a nozzle device 22 for electrostatic electret treatment.

[0097] During the subsequent travel of the electret fiber 12, optionally, the electret fiber may pass through an electric field 46. The electric field 46 may, in particular, be a high-voltage field. Passing through the electric field 46 can similarly or additionally cause stretching of the electret fiber 12. According to... Figure 4 In some embodiments, the electrostatic electret fiber 12 may also be stretched by centrifugal force, either additionally or alternatively.

[0098] according to Figure 4 In the embodiments described above, the electrostatic electret fiber 12 can also be laid or integrated onto the collecting device 28, as already referred to above. Figure 1 As illustrated in the embodiments.

[0099] Figure 5 A side view of the nozzle assembly 22 of the apparatus 10 according to the invention for manufacturing electrostatic electret fibers 12 is shown. The nozzle assembly 22 may have a plurality of two-component nozzles 48 arranged spaced apart from each other. In particular, the two-component nozzles 48 may be arranged along a horizontal line 50 schematically shown here. The two-component nozzles 48 may be configured as flat jet nozzles.

[0100] The openings of the two-component nozzles 48 can be arranged at an angle 52 relative to the horizontal line 50, particularly 1° to 30°, preferably 5° to 20°. Thus, the treated aerosol 24 can be ejected as a horizontal jet 54 from the openings of the respective two-component nozzles 48, the horizontal jet also extending at an angle 52 relative to the horizontal line 50. Through multiple such horizontal jets 54, the treated aerosol 24 can be relatively well distributed in space.

[0101] List of reference numerals in the attached diagram:

[0102] 10 devices

[0103] 12 electrostatic electret fibers

[0104] 14 Fiber Formations

[0105] 16 Spinning Unit

[0106] 18 Polymer Materials

[0107] 20 meltblown nozzle device

[0108] 21 Melt spinning nozzle device

[0109] 22 Nozzle Device

[0110] 23 Solvent Nozzle Device

[0111] 24. Treatment of aerosols

[0112] 26 air channels

[0113] 28 collection devices

[0114] 30 airflow

[0115] 32. Oligomer removal and / or spinning fume extraction

[0116] 34 Cooling

[0117] 36 Primary Air

[0118] 38 Air Inlet Section

[0119] 40 secondary air

[0120] 42 Air Inlet Section

[0121] 44 Level 3 Air

[0122] 46 electric fields

[0123] 48 Two-component nozzles

[0124] 50 horizontal line

[0125] 52 angle

[0126] 54 horizontal jet

[0127] 56 compression rollers

[0128] 56' Sealing Roller

[0129] 58 Spinning tunnel.

Claims

1. A method for producing electrostatically charged fibres (12) which can be used for producing electret fibre formations (14), in which method - fibres are produced from synthetic and / or natural materials, - a polar liquid is atomised by means of a gaseous pressure medium to produce a treatment aerosol (24), - the fibres are treated with the treatment aerosol (24) for electrostatic charging, - wherein, the atomisation is carried out with a polar liquid volume flow in litres per hour to the overpressure of the gaseous pressure medium in millibar in the ratio 0.004 to 0.008 and a polar liquid volume flow of 3.2 litres per hour to 5.2 litres per hour, and / or with a polar liquid mass flow to the gaseous pressure medium mass flow in the ratio 1.4 to 3 and a gaseous pressure medium mass flow of 2.1 kilograms per hour to 2.7 kilograms per hour, and / or with a polar liquid volume flow to the gaseous pressure medium volume flow in the ratio 0.001 to 0.004 and a gaseous pressure medium volume flow of 1.5 cubic metres per hour to 2.5 cubic metres per hour and / or a polar liquid volume flow of 0.002 cubic metres per hour to 0.008 cubic metres per hour.

2. The method of claim 1, wherein, The atomisation of the polar liquid is carried out by means of at least one two-component nozzle (48).

3. The method of claim 2, wherein, The atomisation of the polar liquid is carried out by means of a plurality of two-component nozzles (48).

4. The method according to claim 2 or 3, characterized in that, The atomisation is carried out with a polar liquid volume flow in litres per hour to the overpressure of the gaseous pressure medium in millibar in the ratio 0.004 to 0.008 with a polar liquid volume flow of 4.2 litres per hour in one two-component nozzle (48) or for each two-component nozzle (48).

5. The method according to any one of claims 1 to 3, characterized in that, The atomisation of the polar liquid is carried out with an overpressure of the gaseous pressure medium in the range from 500 millibar to 900 millibar with a polar liquid volume flow in litres per hour to the overpressure of the gaseous pressure medium in millibar in the ratio 0.004 to 0.

008.

6. The method of claim 5, wherein, The atomisation of the polar liquid is carried out with an overpressure of the gaseous pressure medium of 700 millibar.

7. The method of claim 2 or 3, wherein, The atomisation is carried out with a polar liquid mass flow to the gaseous pressure medium mass flow in the ratio 1.4 to 3 with a polar liquid mass flow of 2.1 kilograms per hour to 2.5 kilograms per hour or 2.3 kilograms per hour to 2.7 kilograms per hour in one two-component nozzle (48) or for each two-component nozzle (48).

8. The method according to any one of claims 1 to 3, characterized in that, The fibres are sprayed with the treatment aerosol (24) before the integration into the fibre formation (14) and / or the fibre nonwoven fabric, and / or before the laying on the collecting device (28), and / or before being entrapped by the vacuum source.

9. The method according to any one of claims 1 to 3, characterized in that, The fibres are produced by means of a meltblowing process, and / or the fibres are sprayed with the treatment aerosol (24) directly after the fibres have come out of the meltblowing nozzle device (20), and / or the treatment aerosol (24) is fed into the outlet mouth of the meltblowing nozzle device (20) to spray the fibres.

10. The method according to any one of claims 1 to 3, characterized in that, The fibers after being sprayed with the treatment aerosol (24) are integrated into a fiber formation (14) and / or a fiber nonwoven and / or are laid on a collecting device (28), and / or the electrostatically polarized fibers (12) integrated into a fiber formation (14) and / or a fiber nonwoven and / or laid on a collecting device (28) have a residual moisture of less than 6% without active drying.

11. The method of claim 10, wherein, The electrostatically polarized fibers (12) integrated into a fiber formation (14) and / or a fiber nonwoven and / or laid on a collecting device (28) have a residual moisture of less than 5% without active drying.

12. An apparatus (10) for manufacturing electrostatically polarized fibers (12), the apparatus being designed to carry out the method according to any one of claims 1 to 11, the apparatus having - a spinning device (16) for producing fibers from synthetic and / or natural materials, and - a nozzle device (22) for generating a treatment aerosol (24) by atomizing a polar liquid by means of a gaseous pressure medium and for electrostatically polarizing the fibers by spraying the fibers with the treatment aerosol (24), - wherein, The nozzle device (22) is designed to atomize at a quotient of the volume flow of the polar liquid in liters per hour and the overpressure of the gaseous pressure medium in millibar of 0.004 to 0.008, and / or at a quotient of the mass flow of the polar liquid and the mass flow of the gaseous pressure medium of 1.4 to 3, and / or at a quotient of the volume flow of the polar liquid and the volume flow of the gaseous pressure medium of 0.001 to 0.

004.

13. The apparatus (10) according to claim 12, characterized in that The nozzle device (22) has one or a plurality of bi-component nozzles (48), wherein the plurality of bi-component nozzles (48) are arranged at a distance of 4 cm to 10 cm from one another, and / or the openings of the bi-component nozzles (48) are arranged at an angle (52) with respect to the horizontal (50).

14. The apparatus (10) according to claim 13, characterized in that The plurality of bi-component nozzles (48) are arranged at a distance of 5 cm to 8 cm from one another.

15. The apparatus (10) according to claim 14, characterized in that The plurality of bi-component nozzles (48) are arranged at a distance of 7 cm from one another.

16. The apparatus (10) according to claim 13, characterized in that The angle (52) is 1° to 30°.

17. The apparatus (10) according to claim 16, characterized in that The angle (52) is 5° to 20°.

18. The apparatus (10) according to any one of claims 12 to 17, characterized by The spinning device (16) is designed as a meltblowing device, a melt spinning device having Exxon nozzles or one or a plurality of coaxial nozzles or nonwoven nozzles, or a solvent spinning device.

19. An electret product, which is an electret fiber and / or an electret fiber nonwoven, manufactured using the method according to any one of claims 1 to 11 and / or by the apparatus (10) according to any one of claims 12 to 18.

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