Filter media containing meltblown nonwoven fabric and their use

Abstract

To provide an improved filter medium. [Solution] The present invention relates to a filter material comprising I) a first nonwoven meltblown layer, wherein the meltblown nonwoven fabric comprises a) 20 to 80% by weight of at least one styrene-based thermoplastic elastomer and b) 20 to 80% by weight of at least one polyolefin. The present invention also relates to the use of filter materials for coffee filters, coffee capsule filters, compressed air filters and face masks.

Description

[Technical Field]

[0001] The present invention I) The first layer of the meltblown nonwoven fabric A filter material containing a meltblown nonwoven fabric, a) at least one styrene-based thermoplastic elastomer, and b) at least one polyolefin The present invention relates to filter media, including, and to the use of such filter media for coffee filters, particularly filters for coffee capsules, compressed air filters, or face masks. [Background technology]

[0002] There are basically two different types of filter media used to remove solid impurities, such as dust particles, from liquids and gases.

[0003] The first type is a depth filter medium, which is configured to absorb and accumulate the maximum amount of dust before clogging. Such a filter medium ideally has an asymmetric structure, meaning that the pore size and fiber diameter become progressively smaller in the direction of flow. The effect of this is that larger dust particles preferentially adhere to and accumulate on the top layer of the depth filter medium, while smaller dust particles also adhere after penetrating further in. This distribution of dust particles throughout the depth of the filter medium allows a relatively large amount of dust to accumulate before the filter medium becomes so clogged that the flow of liquid or gas through the accumulated dust particles is severely obstructed. Such filters cannot be cleaned and must be removed and disposed of after reaching a specified pressure difference.

[0004] The second type is surface filter media. In this type of filter, the first filtration layer in the flow direction has the smallest pore size and fiber diameter. The next layer usually has wider pores and thicker fibers. It mainly serves as a carrier for the first filtration layer, providing the necessary mechanical strength and rigidity to the entire filter. Ideally, all dust particles, whether large or small, adhere to the first layer and do not penetrate into the filter media.

[0005] As a result, a cake of dust forms on the surface of the filter media over time, obstructing the flow of liquid or gas indefinitely. Because the dust cake sits fairly loosely on the surface of the filter media, it can also be removed relatively easily. Removal is ideally done by light tapping, shaking, washing, pressure pulses, or backwashing. In the case of backwashing and pressure pulses, the filter media is briefly exposed to a clean liquid or clean gas in the opposite direction to the original flow. This detaches the dust cake from the surface of the filter media, and the thus-cleaned filter media is ready for the next filtration cycle. In the case of backwashing, this is done with a washing solution at a relatively low flow rate over a long period of time, while in the case of pressure pulses, the washing solution is applied in strong, short pulses.

[0006] Surface filtration media can be either single-layer or multi-layered. Single-layer surface media include, for example, filter paper with smaller pores on the inlet side than on the outlet side, or needle felt or spunbond nonwoven fabric with one side densified. Spunbond nonwoven fabric with one side densified is described as an example in reference DE10039245A1. Single-layer media, despite densification on one side of the surface, still have relatively large pores on the densified side and are only suitable for fairly coarse dust. Finer dust particles penetrate deeply into the media and cannot be removed. As a result, the filter media or filter element containing the filter media becomes clogged relatively quickly and must be replaced.

[0007] To evaluate the performance of a filter, for example, effective life has been introduced as a criterion. The effective life, or other lifespan, of a filter element is the time elapsed from the first use of the filter element until the specified maximum pressure difference is reached. The larger the filtration area of ​​the filter element, and the better the dust accumulation capacity of the filter element due to its surface properties, the longer the effective life.

[0008] A filter material having at least two layers is used to adhere fine dust, such as colored powder, crushed resin, or cement. Either a membrane, a nanofiber layer, or a meltblown layer is applied as a filter layer to a carrier having high mechanical strength and rigidity. The filter layer is the first layer when viewed in the flow direction.

[0009] An example of a filter media having a meltblown layer is described in German publication DE4443158A1. The advantage of such a filter media is its relatively low cost. However, the disadvantage here is that the mechanical strength of the meltblown layer is not very high.

[0010] The use of meltblown nonwovens as filter media has been known for a long time. The meltblown process is described in detail, for example, A. van Wente, "Superfine Thermoplastic Fibers," Industrial Engineering Chemistry, Vol. 48, pp. 1342-1346. This process makes it possible to produce substantially continuous fibers having a diameter of 0.3 to 15 μm. The smaller the fiber diameter and the higher the fiber density relative to each other, the better the suitability of the meltblown nonwoven for separating fine dust from gases and liquids. Unfortunately, however, the mechanical strength of the fibers also decreases with fiber diameter. Whenever mechanical stress is applied to a meltblown nonwoven thus produced, for example, when fingers rub across the surface of the filter media or within the folding of the filter media during the subsequent manufacturing of filter elements, some fibers will break and dendrites will form. Dendrites refer to frayed meltblown fibers of varying lengths that protrude from the surface of a meltblown nonwoven fabric at angles ranging from 10° to 90°. Since filter media are typically folded during the manufacturing of filter elements, dendrites protrude into the unfolded, empty space on the inflow side. The protrusion of dendrites from the surface of the meltblown nonwoven fabric increases if the meltblown nonwoven fabric can become electrostatically charged. Filter elements with such filter media made from meltblown nonwoven fabrics tend to clog even after a short time, resulting in the filter element having to be replaced.

[0011] As described in DE4443158A1 and DE10039245A1, it is possible to improve mechanical strength and surface smoothness by performing thermal surface densification using a calender. However, surface densification, which clearly increases the mechanical strength of meltblown nonwovens, simultaneously adversely affects porosity and air permeability. Furthermore, thermal densification is an additional processing step. DE4443158A1 also discloses that meltblown nonwovens can be bound with a binder, either alone or with a carrier, to improve abrasion resistance and refining resistance. However, this method also adversely affects the air permeability of the filter material and is an additional costly process.

[0012] Various methods for producing the corresponding filter media are known to those skilled in the art. In particular, the meltblown and spunbond methods are suitable for producing nonwoven fabrics from a wide variety of polymers.

[0013] By precisely selecting raw materials, it is possible to create nonwoven fabrics with a variety of properties. For example, there are elastic nonwoven fabrics, which have been used for a considerable time in a wide range of applications. The polymer most commonly used in such nonwoven fabrics is thermoplastic polyurethane, which has many advantages, such as good stability and adjustable elasticity. In addition, there are already publications on melt-spun nonwoven fabrics of TPA (thermoplastic polyamide elastomer) and TPC (thermoplastic copolyester elastomer).

[0014] A disadvantage of TPU (thermoplastic polyurethane) meltblown nonwoven fabrics is their limited suitability in the food sector. Chain decomposition and hydrolysis can produce aromatic primary amines, some of which are carcinogenic to humans.

[0015] A further disadvantage of TPU meltblown nonwoven fabrics is that they cannot be electrostatically charged. However, electrostatically charged nonwoven fabrics are advantageous for various applications, such as face masks. [Overview of the project]

[0016] For these reasons, it was an object of the present invention to provide an improved filter medium which at least partially mitigates the disadvantages known from the prior art.

[0017] This object is achieved by a filter medium comprising I) a first layer of melt-blown nonwoven fabric wherein the melt-blown nonwoven fabric comprises a) at least one styrenic thermoplastic elastomer, and b) at least one polyolefin and is realized by the filter medium.

Embodiments for Carrying Out the Invention

[0018] As used herein, the term "melt-blown nonwoven fabric" means any nonwoven fabric that can be produced by the melt-blown process known to those skilled in the art for the production of filter media, i.e., a process in which a molten polymer is extruded at high speed into a high-temperature gas stream, thereby converting the molten polymer into fibers.

[0019] As used herein, the term "filter medium" refers to any device that can be used for the treatment of filtration, i.e., a mechanical or physical method of separating one substance from another, such as solids, liquids, and gases, with the aid of the interposition of the filter medium.

[0020] The thicknesses of the layers of the first, second, and third layers and the overall thickness of the filter medium are the thicknesses under a pressure of 0.5 kPa according to DIN EN ISO9073-2:1997-02.

[0021] A thermoplastic elastomer (TPE) is a polymer or polymer mixture that has behavior equivalent to that of conventional elastomers at room temperature but can be plastically deformed when heat is supplied and thus exhibits thermoplastic properties. Thermoplastic elastomers regularly contain a hard phase and a soft phase, where the hard phase is involved in the thermoplastic processability and the soft phase is involved in the elastic properties.

[0022] Thermoplastic styrene elastomers (TPS) are the most rubber-like of the TPEs and are noteworthy for their excellent flexibility and elasticity. With polystyrene (PS) as the rigid segment, product variations are classified based on differences in the materials of the flexible segment into SBS (S: styrene, B: butadiene), SIS (I: isoprene) and its hydrogenation variations, SEBS (E: ethylene, B: butylene), and SEPS (P: propylene). SEBS and SEPS possess excellent thermal and weather resistance. They are used in a wide range of applications due to their good balance of moldability, flexibility, and mechanical strength.

[0023] In block copolymers, such as styrene block copolymers (SBCs), a single molecule contains both a hard phase and a soft phase.

[0024] This invention describes a meltblown nonwoven fabric, preferably an elastic meltblown nonwoven fabric based on TPS, where TPS is a thermoplastic elastomer based on styrene block copolymer, which can be processed into a mixture with polyolefin. The olefin structure of such polymers makes it impossible to release aromatic amines and has a low tendency to hydrolyze, thus making it even more suitable for use in food applications.

[0025] Preferred styrene block copolymers are selected from the group consisting of styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), styrene-isobutylene-styrene (SIBS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), and mixtures thereof. SEBS, SIS, and SBS are particularly preferred.

[0026] Thermoplastic elastomers, also known as TPS, are mixtures based on, for example, SBS or SEBS. In fact, the terms SBS or SEBS are frequently used to describe the components when they are actually the raw materials. Describing the components as SBS or SEBS allows for information regarding the general performance level and properties of the components.

[0027] SBS is based on a biphasic block copolymer having rigid and flexible segments. The styrene terminal blocks ensure thermoplastic properties, while the butadiene intermediate blocks ensure elastomeric properties.

[0028] When SBS is hydrogenated, the elimination of C=C bonds in the butadiene component produces ethylene and butylene in the intermediate block, thus becoming SEBS. SEBS is noteworthy for its improved thermal stability, mechanical properties, and chemical stability. SEBS components adhere to technical thermoplastic resins. When adhering to PP, either SBS or SEBS can be used.

[0029] SEPS, or styrene-ethylene-propylene-styrene, also known as styrene-ethylene / propylene-styrene (SEPS), is a thermoplastic elastomer (TPE) that behaves like rubber without vulcanization. SEPS is extremely flexible, has excellent thermal and UV stability, and is easy to process. It is produced by the selective partial hydrogenation of styrene-isoprene-styrene (SIS), which enhances thermal stability, weather resistance, and oil resistance, making SEPS suitable for steam sterilization. However, hydrogenation also reduces mechanical efficiency and increases the cost of the polymer. SEPS elastomers are often mixed with other polymers to enhance their performance.

[0030] Particularly suitable styrene block copolymers are styrene / conjugated diene / styrene triblock copolymers, their hydrogenated derivatives, or mixtures thereof. The conjugated diene is typically selected from butadiene and isoprene.

[0031] Suitable styrene block copolymers according to the present invention preferably contain at least 25% by weight of styrene, more preferably 25 to 65% by weight of styrene, particularly preferably 35% to 60% by weight, particularly 40% to 60% by weight of styrene, and up to 75% by weight, more preferably 75% to 35% by weight, particularly preferably 65% ​​to 40% by weight, particularly 60% to 40% by weight of conjugated dienes. Polystyrene block copolymers having a high styrene content of 57% by weight are available, for example, under the trade name Kraton® A1535H.

[0032] Polyolefins preferably include thermoplastic crystalline polyolefin homopolymers and copolymers. Suitable polyolefins are preferably homopolymers and copolymers of olefins having 2 to 8 carbon atoms, such as ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene, as well as copolymers of such olefins with (meth)acrylates and / or vinyl acetate.

[0033] The polyolefin present in the meltblown nonwoven fabric is more preferably a thermoplastic polyolefin.

[0034] Thermoplastic polyolefins can be used alone or in mixtures. Preferred thermoplastic polyolefins are polypropylene (PP) and polyethylene (PE), where polypropylene refers to both homopolymers and copolymers of propylene and other olefins such as ethylene or α-olefins having 4 to 16 carbon atoms, and mixtures thereof, in about 1% to about 20% by weight. Polypropylene can be highly crystalline, isotactic, or syndiotactic polypropylene.

[0035] The polyolefin is more preferably either polypropylene or polyethylene.

[0036] Prioritizing the first layer of meltblown nonwoven fabric, a) At least one styrene-based thermoplastic elastomer in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 21 to 80% by weight, and b) At least one polyolefin in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, and more preferably 20 to 79% by weight. It is a filter material that contains [something].

[0037] Of particular priority is the first layer of the meltblown nonwoven fabric. a) At least one styrene-based thermoplastic elastomer in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 21 to 80% by weight, and b) At least one polyolefin in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, and more preferably 20 to 79% by weight. It is a filter material consisting of [the following].

[0038] Prioritizing the first layer of meltblown nonwoven fabric, a) At least one styrene-based thermoplastic elastomer in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 21 to 80% by weight, and b) 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 20 to 79% by weight of polypropylene It is a filter material that contains [something].

[0039] Of particular priority is the first layer of the meltblown nonwoven fabric. a) At least one styrene-based thermoplastic elastomer in an amount of 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 21 to 80% by weight, and b) 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 20 to 79% by weight of polypropylene It is a filter material consisting of [the following].

[0040] The ratio of styrene-based thermoplastic elastomer to polyolefin is preferably 1 / 99 to 99 / 1, more preferably 10 / 90 to 90 / 10, more preferably 10 / 90 to 80 / 20, more preferably 20 / 80 to 80 / 20, more preferably 40 / 60 to 80 / 20, and particularly preferably 60 / 40 to 70 / 30. The higher the proportion of styrene-based thermoplastic elastomer, the softer and more elastic the meltblown nonwoven fabric becomes. The higher the proportion of polyolefin, the harder the meltblown nonwoven fabric becomes, and the easier it is to electrostatically charge the meltblown nonwoven fabric. Therefore, those skilled in the art can adjust the ratio of styrene-based thermoplastic elastomer to polyolefin accordingly for the desired use.

[0041] The styrene-based thermoplastic elastomers and / or polyolefins used in accordance with the present invention may further contain particularly non-hygroscopic additives. Examples of such additives include fillers, e.g., inorganic fillers, e.g., calcium carbonate, clay, silicon dioxide, talc and titanium dioxide; adhesion promoters; biocides; antifogging agents; binders, foaming agents and foamers; dispersants; fire retardants and flame retardants and smoke suppressants; impact modifiers; crosslinking agents; lubricants; mica; pigments, colorants and dyes; additional processing aids; separating agents; silanes, titanates and zirconates; lubricants and anti-tackling agents; stabilizers; stearates; ultraviolet absorbers; viscosity modifiers; waxes; and combinations thereof.

[0042] The melt-blown nonwoven fabric of the present invention preferably contains fibers having an average diameter (d) of less than 15 μm, more preferably 1 μm ≤ d < 10 μm, and even more preferably 1 μm ≤ d ≤ 8 μm. For use in face masks, an average diameter (d) of 1 μm ≤ d < 4 μm is particularly suitable. As can be inferred from this, the melt-blown nonwoven fabric having a specified fiber diameter (fiber thickness) can meet the standards of types I, II, and IIR face masks according to DIN EN 14683:2019-10 or FFP1, FFP2, and FFP3 according to DIN EN 149:2009-08, enabling the use of the filtration layer of the present invention in face masks.

[0043] In the present invention, "average diameter" and "diameter" are distinguished. This difference is important because no information can be obtained regarding the amount of fine fibers having a specific diameter from the average diameter.

[0044] The first layer of the melt-blown nonwoven fabric preferably has a thickness exceeding 0.20 mm under a pressure of 0.5 kPa according to DIN EN ISO 9073-2:1997-02. More preferably, the thickness of the nonwoven fabric layer is 0.30 - 1.20 mm, particularly 0.40 - 1.00 mm.

[0045] The mass per unit area of the first layer of the melt-blown nonwoven fabric is preferably between 15 g / m 2 ~400 g / m 2 , more preferably between 20 g / m 2 ~300 g / m 2 . A range between 25 - 200 g / m 2 is particularly preferred.

[0046] The air permeability of the first layer of the melt-blown nonwoven fabric is preferably 50 - 2000 l / m 2 s at 200 Pa, more preferably 200 - 1500 l / m 2 s. For use in face masks, a range between 100 - 700 l / m 2 s is particularly suitable. For use in compressed air filters, a range of 50 - 500 l / m 2The air permeability between s is particularly suitable. For use in coffee filters and coffee capsule filters, 700-1500 l / m³ is recommended. 2 The air permeability between s is particularly suitable.

[0047] The longitudinal (MD) tensile strength of the first layer of the meltblown nonwoven fabric is preferably 5 to 100 N / 5 cm.

[0048] The transverse (CD) tensile strength of the first layer of the meltblown nonwoven fabric is preferably 5 to 80 N / 5 cm.

[0049] The longitudinal (MD) break elongation of the first layer of the meltblown nonwoven fabric is preferably 100-500%, and particularly preferably in the ranges of 150-400% and 300-500%.

[0050] The transverse (CD) break elongation of the first layer of the meltblown nonwoven fabric is preferably 100-500%, and particularly preferably in the range of 150-400% and 300-500%.

[0051] The water penetration resistance at 60 bar / min is preferably 10 to 60 mbar, more preferably 15 to 50 mbar.

[0052] The meltblown nonwoven fabric is preferably manufactured as a single layer and can be combined with a second layer of nonwoven fabric or a different woven product or fabric. This second layer preferably has a thickness of less than 0.50 mm under a pressure of 0.5 kPa according to DIN EN ISO9073-2:1997-02. The thickness of the second layer is more preferably 0.10 to 0.40 mm, and particularly 0.10 to 0.35 mm.

[0053] The second layer consists of a nonwoven or woven fabric, and the preference is to use a spunbond nonwoven or carded nonwoven fabric made of polypropylene, polyester, or an elastic thermoplastic polymer.

[0054] Nonwoven fabrics are fabrics manufactured from fibers and bound together in various ways. While nonwoven fabrics can be manufactured from fibers without any restrictions, it is not always necessary to use fibers intended for woven fabrics.

[0055] "Textile products" or "textiles" are linear two- or three-dimensional structures formed from woven materials (natural or synthetic fibers) and non-woven materials. In distinction from nonwovens, the term "textile" is used in this invention for two-dimensional materials, the main components of which are woven fibers, i.e., fibers that can be processed in a textile manufacturing method, and in particular spinnable, and processed into the form of yarn. Since woven fibers are spinnable, the main difference between textile products and nonwovens in terms of weaving direction is that, therefore, the base material of a textile is also a unidirectional weave, and all reinforcing threads are also oriented in one direction.

[0056] The unit area mass of the second layer is preferably 10 g / m². 2 ~120g / m 2 More preferably 12g / m 2 ~90g / m 2 That is the case.

[0057] The second layer can be manufactured using any known method. The preference is to use a nonwoven fabric which may be bonded chemically and / or thermally and / or mechanically.

[0058] The second layer is preferably formed from a polymer selected from the group consisting of polypropylene, polyester, or elastic thermoplastic polymers. The second layer is preferably formed from a polymer selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA), polyphenylene sulfide (PPS), polyolefin (PO), thermoplastic polyurethane (TPU), thermoplastic copolyester (TPC), thermoplastic styrene block copolymer (TPS), or mixtures thereof.

[0059] The second layer is preferably formed from a polymer containing or consisting of polyamide (PA). At least a portion of the polyamide (PA) is preferably thermoplastic polyamide (TPA). The polyamide (PA) is preferably thermoplastic polyamide (TPA). The polyamide (PA) is preferably a thermoplastic polyamide elastomer.

[0060] The second layer is preferably formed from a polymer containing or comprising a thermoplastic copolyester (TPC). The thermoplastic copolyester (TPC) is preferably a thermoplastic copolyester elastomer.

[0061] The second layer is preferably formed from a polymer containing or comprising a thermoplastic styrene block copolymer (TPS). The thermoplastic styrene block copolymer (TPS) is preferably a thermoplastic styrene elastomer.

[0062] In this specification, "thermoplastic" is understood to mean the behavior of a polymer that is easily deformable within a specific temperature range, and this behavior is reversible.

[0063] In this specification, "elastomer" or "elastic polymer" is understood to mean a dimensionally stable polymer that is elastically deformable, for example, under tensile and compressive stress, and has a glass transition temperature lower than the operating temperature.

[0064] More preferably, the second layer may include or consist of a nonwoven or woven fabric of polypropylene, polyester, or an elastic thermoplastic polymer.

[0065] More preferably, the second layer may include or consist of a spunbond nonwoven fabric made of polypropylene, polyester, or an elastic thermoplastic polymer. Most preferably, the second layer is a spunbond nonwoven fabric made of polypropylene, polyester, or an elastic thermoplastic polymer. Most preferably, the second layer may include or consist of a spunbond nonwoven fabric made of polypropylene or polyester.

[0066] More preferably, the second layer may include, or consist of, a card-type nonwoven fabric made of polypropylene, polyester, or an elastic thermoplastic polymer. Most preferably, the second layer is a card-type nonwoven fabric made of polypropylene, polyester, or an elastic thermoplastic polymer. Most preferably, the second layer may include, or consist of, a card-type nonwoven fabric made of polypropylene or polyester.

[0067] The first and second layers are preferably identical, i.e., both the first and second layers preferably comprise a meltblown nonwoven fabric containing at least one styrene-based thermoplastic elastomer and at least one polyolefin. More preferably, in both the first and second layers, the styrene-based thermoplastic elastomer is selected from the group consisting of styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), styrene-isobutylene-styrene (SIBS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), and mixtures thereof, and the polyolefin is polypropylene or polyethylene.

[0068] Apart from the first and second layers, which are made of meltblown nonwoven fabric, the filter material may also include a third layer, preferably as a protective layer. The filter material preferably includes a third layer made of nonwoven or woven fabric, and the first, second, and third layers are arranged in a stack.

[0069] Suitable polymers for the third layer include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA), polyphenylene sulfide (PPS), polyolefin (PO), thermoplastic polyurethane (TPU), thermoplastic copolyester (TPC), thermoplastic styrene block copolymer (TPS), or mixtures thereof.

[0070] The third layer is preferably formed from a polymer containing or comprising polyamide (PA). Preferably, at least a portion of the polyamide (PA) is thermoplastic polyamide (TPA). The polyamide (PA) is preferably thermoplastic polyamide (TPA). The polyamide (PA) is preferably a thermoplastic polyamide elastomer.

[0071] The third layer is preferably formed from a polymer containing or comprising a thermoplastic copolyester (TPC). The thermoplastic copolyester (TPC) is preferably a thermoplastic copolyester elastomer.

[0072] The third layer is preferably formed from a polymer containing or comprising a thermoplastic styrene block copolymer (TPS). The thermoplastic styrene block copolymer (TPS) is preferably a thermoplastic styrene elastomer.

[0073] The third layer can be manufactured by either a nonwoven or woven method. The spunbond method is preferred.

[0074] More preferably, the third layer may include or consist of a nonwoven or woven fabric made of polypropylene or polyester.

[0075] Most preferably, the third layer may include or consist of a spunbond nonwoven fabric made of polypropylene or polyester.

[0076] The first, second, and third layers are preferably identical, i.e., the first, second, and third layers preferably all comprise a meltblown nonwoven fabric containing at least one styrene-based thermoplastic elastomer and at least one polyolefin. More preferably, in all of the first, second, and third layers, the styrene-based thermoplastic elastomer is selected from the group consisting of styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), styrene-isobutylene-styrene (SIBS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), and mixtures thereof, and the polyolefin is polypropylene or polyethylene.

[0077] The average diameter (d) of the fibers in the third layer is preferably 2 μm ≤ d ≤ 50 μm, more preferably 5 μm ≤ d ≤ 40 μm, and most preferably 10 μm ≤ d ≤ 30 μm.

[0078] The third layer is preferably 8 g / m² 2 ~100g / m 2 , comfortable 10g / m 2 ~50g / m 2 It has a mass per unit area.

[0079] For the manufacture of filter media, a first layer consisting of meltblown nonwoven fabric can be bonded to a second layer consisting of nonwoven or woven fabric. For this purpose, any method known to those skilled in the art, such as needling, waterjet needling, thermal methods (i.e., calendering and ultrasonic bonding) and chemical methods (i.e., bonding with adhesives), can be used.

[0080] A first layer, which is made of meltblown nonwoven fabric, is preferably bonded to a second layer, which is made of nonwoven or woven fabric, by spot carving.

[0081] The third layer may preferably be similarly bonded to the second layer by spot coating, or it may be positioned without being bonded.

[0082] In addition, the first layer, which is composed of meltblown nonwoven fabric, can be electrostatically charged meltblown nonwoven fabric. Electrostatic charging of the fibers can increase filtration efficiency. This is particularly advantageous for use as a filter material in face masks. Corona charging, hydrocharging, or charging with polar liquids such as water, and triboelectric charging, or a combination thereof, are known charging methods. Corona charging is the most commonly used method for the mass production of charged filter materials.

[0083] The term "corona charging" as used herein relates to a method for producing a charged nonwoven fabric, wherein fibers of a nonconductive polymer material are exposed to an AC and / or DC corona charging apparatus, thereby causing the fibers to become charged.

[0084] The term “water-induced charging” is also known as “hydrocharging,” and as used herein, relates to a method for producing a charged nonwoven fabric in which fibers are exposed to a water mist, thereby adding an electric charge to the fibers. The process can be carried out either immediately after the formation of the fibers or after the nonwoven fabric has been formed from the fibers.

[0085] The possibility of electrostatically charging the first layer of the meltblown nonwoven fabric, thereby obtaining a filter material containing the first layer of electrostatically charged meltblown nonwoven fabric, and thus good suitability for the food sector, is a further advantage over meltblown nonwoven fabrics made from TPU, which cannot be electrostatically charged. Therefore, the filter material containing the first layer of electrostatically charged meltblown nonwoven fabric according to the present invention is particularly suitable for use in face masks.

[0086] An additional advantage of the first layer of meltblown nonwoven fabric is its water repellency, which is represented by its high water penetration resistance. The water penetration resistance of the first layer made of meltblown nonwoven fabric at 60 mbar / min is preferably in the range of 15 to 100 mbar, more preferably 20 to 60 mbar.

[0087] The filter material is preferably used in coffee filters, particularly in filters for coffee capsules. When used as a coffee filter, the filter material is preferably a single-layer filter material comprising only a first layer made of meltblown nonwoven fabric.

[0088] The filter media is preferably used in compressed air filters. When used as a compressed air filter, the filter media is preferably a multilayer filter media, particularly a two- or three-layer filter media, comprising a first layer of meltblown nonwoven fabric, a second layer of nonwoven or woven fabric, and optionally a third layer of nonwoven or woven fabric.

[0089] The filter material is preferably used in face masks. When used as a face mask, the filter material is preferably a multilayer filter material, particularly a two- or three-layer filter material, comprising a first layer of meltblown nonwoven fabric, a second layer of nonwoven or woven fabric, and optionally a third layer of nonwoven or woven fabric. In addition, when used in face masks, the first layer is preferably a layer of electrostatically charged meltblown nonwoven fabric. The meltblown nonwoven fabric is preferably electrostatically charged by corona charging or by water charging.

[0090] Test method Mass per unit area according to DIN EN29073-1:1992-08.

[0091] Thickness under a pressure of 0.5 kPa, according to DIN EN ISO9073-2:1997-02.

[0092] Measurement area 20 cm² according to DIN EN ISO9237:1995-12. 2 And air permeability at a pressure difference of 200 Pa.

[0093] Tensile strength (MD and CD) according to DIN EN29073-3:1992-08, with strip width (50 mm), clamped length (100 mm), and speed (100 mm / min).

[0094] Elongation at break (MD and CD) according to DIN EN29073-3:1992-08, with a strip width of 50 mm, clamp length of 100 mm, and speed of 100 mm / min.

[0095] Water penetration resistance at a speed of 60 mbar / min, according to DIN EN ISO811:2018-08.

[0096] Respiratory resistance and permeability were measured according to EN143:2007-02, using paraffin oil as the test aerosol, with an airflow velocity of 95 l / min and a sample size of 100 cm². 2 The measurement was taken over a period of 210 seconds. Any suitable device, such as a Lorenz face mask test stand, can be used.

[0097] Fiber diameter i. Principle of Measurement Images are recorded at a specified magnification using a scanning electron microscope. These are then analyzed using automated software. Measurement areas containing fiber intersections and therefore not showing fiber diameter are manually removed. Fiber bundles are considered as fibers as a whole.

[0098] ii. Equipment For example, Phenom with accompanying Fibermetric V2.1 software Fei scanning electron microscope. It is possible to use any suitable equipment and any suitable software.

[0099] iii. Execution of the test a. Sputter coating of the sample b. Random imaging using optical imaging; the regions identified in this way are then imaged using SEM at a 1000x magnification. c. Determination of fiber diameter by the one-click method; each fiber must be included once. d. The distribution of mean values ​​and fiber diameters is evaluated using Excel with data obtained by Fibermetric. At least 100 fibers will be evaluated. The percentage of fibers with a diameter of <1.00 μm is recorded similarly. e.Error / standard deviation The standard deviation is also estimated. [Examples]

[0100] The following is a description of an embodiment of the filter material of the present invention, which consists of a first layer of meltblown nonwoven fabric. Polymer: 65% SEBS, 35% PP

[0101] [Table 1]

[0102] The filter media described in Examples 1 and 2 can be used in face masks.

[0103] The filter material described in Example 3 can be used as a coffee filter, and in particular as a filter for coffee capsules.

[0104] The filter material described in Example 4 can be used in a compressed air filter.

Claims

1. I) The first layer of the meltblown nonwoven fabric A filter material comprising, wherein the first layer of the meltblown nonwoven fabric is a) 20 to 80% by weight of at least one styrene-based thermoplastic elastomer, and b) 20 to 80% by weight of at least one polyolefin Filter media, including

2. The filter material according to claim 1, wherein the styrene-based thermoplastic elastomer is selected from the group consisting of styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), styrene-isobutylene-styrene (SIBS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), and mixtures thereof.

3. The filter material according to claim 1 or 2, wherein the polyolefin is either polypropylene or polyethylene.

4. The filter material according to claim 1 or 2, wherein the meltblown nonwoven fabric contains fibers having an average diameter (d) of less than 15 μm.

5. The air permeability of the first layer of the meltblown nonwoven fabric is 50 to 2000 l / m². ２ The filter material according to claim 1 or 2, wherein s.

6. II) A second layer of nonwoven or woven fabric A filter material according to claim 1 or 2, comprising:

7. The filter material according to claim 6, wherein the nonwoven or woven fabric of the second layer is formed from a polymer selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA), polyphenylene sulfide (PPS), polyolefin (PO), thermoplastic polyurethane (TPU), thermoplastic copolyester (TPC), thermoplastic styrene block copolymer (TPS), or mixtures thereof.

8. III) The filter material according to claim 6, comprising a third layer of nonwoven or woven fabric, wherein the first layer, the second layer, and the third layer are arranged in a stack of one layer each.

9. Use of the filter material according to claim 1 or 2 for a coffee filter.

10. Use of the filter material according to claim 9 for a coffee capsule filter.

11. Use of the filter material according to claim 1 or 2 for a compressed air filter.

12. Use of the filter material according to claim 1 or 2 for a face mask.

Images