Woven fabric for extraction filter and extraction filter

Abstract

The purpose of the present invention is to provide: a cheap, disposable woven fabric that is for an extraction filter and demonstrates extraction performance that makes it possible to transmit more liquid and more effectively capture fine powdered residue from the extraction of coffee or the like; and an extraction filter. According to the present invention, a woven fabric for an extraction filter includes: multifilaments that are included in at least one of the warp and the weft of the woven fabric; and monofilaments that are orthogonal to the multifilaments. The total fineness (T1) of the multifilaments is at least 80 dtex, the total fineness (T2) of the monofilaments is no more than 40 dtex, and the ratio (T1 / T2) of the total fineness (T1) of the multifilaments to the total fineness (T2) of the monofilaments is 2.0–5.0.

Description

Woven fabric for extraction filter and extraction filter

[0001] The present invention relates to a woven fabric for an extraction filter and an extraction filter.

[0002] Conventionally, woven and knitted fabrics using synthetic fibers as extraction filters for flavored beverages have been widely studied, and woven and knitted fabrics that can achieve both the transparency of tea leaves filled in bags and the permeability of beverages have been proposed according to the yarns used and the design of the woven and knitted fabrics.

[0003] For example, by using a core-sheath multifilament composed of 2 to 5 filaments in the weft yarn of the woven fabric, it becomes easy to control the size of the mesh opening with a small amount of yarn used, and an inexpensive extraction filter for flavored beverages with good extraction properties, firmness, transparency, and high quality has been proposed (see, for example, Patent Document 1).

[0004] Also, by using a composite yarn of raw silk made of ultra-fine fibers and crimped yarn made of ultra-fine fibers in the woven fabric and spraying a high-pressure water stream on the surface of the woven fabric, a fabric for food filtration that satisfies the effect of capturing fine dregs in, for example, coffee extraction, having a large surface area and a large number of voids of the fibers has been proposed (see, for example, Patent Document 2).

[0005] JP-A-2021-4440 JP-A-2005-68594

[0006] However, the above-mentioned Patent Document 1 is a filter excellent for extracting tea leaves that achieves both transparency and permeability, has a large mesh opening, and a small number of multifilaments. Therefore, even if the mesh opening is reduced, the voids due to the twist between the filaments during weaving and processing become large. Therefore, it did not satisfy the effect of capturing fine powder dregs in, for example, coffee extraction.

[0007] Furthermore, while the proposed fabric in Patent Document 2 satisfies the effect of capturing fine powder residue in coffee extraction, it requires the use of two types of ultrafine fibers to create a composite yarn, and the fabrication process is complex, requiring processes such as weight reduction and water jet punching. As a result, it is more expensive than paper filters, which are the mainstream for coffee extraction filters, and although it can be reused, it does not have sufficient versatility.

[0008] In view of the above issues, this disclosure aims to provide a textile for extraction filters and an extraction filter that have extraction performance that more effectively captures fine powder residue in the extraction of coffee and the like, and allows liquid to pass through more effectively, and that are inexpensive and disposable.

[0009] This disclosure has the following configuration to solve the above problems: (1) A fabric for extraction filters, comprising multifilaments included in at least one of the warp or weft threads of the fabric and monofilaments perpendicular to the multifilaments, wherein the total fineness (T1) of the multifilaments is 80 dtex or more, the total fineness (T2) of the monofilaments is 40 dtex or less, and the ratio (T1 / T2) of the total fineness (T1) of the multifilaments to the total fineness (T2) of the monofilaments is 2.0 to 5.0. (2) The fabric for extraction filters according to (1) above, wherein the number of filaments of the multifilaments is 10 to 40. (3) The fabric for extraction filters according to (1) or (2) above, wherein the maximum distance (L) between single filaments of the multifilaments is 40 μm or less. (4) The fabric for extraction filters according to any one of (1) to (3) above, wherein the multifilaments and monofilaments are polylactic acid fibers. (5) A fabric for extraction filters according to any one of (1) to (4) above, wherein the warp threads are monofilaments and the weft threads are multifilaments. (6) An extraction filter made of the fabric for extraction filters according to any one of (1) to (5) above.

[0010] The fabric for extraction filters of this disclosure has excellent extraction performance and, depending on the embodiment, can also have appropriate firmness and resilience, and can be easy to handle after filter molding.

[0011] Figure 1 is a schematic diagram showing an example of the extraction filter fabric of the present disclosure. Figure 2 is a photographic substitute for a drawing showing an example of the surface of the extraction filter fabric of the present disclosure.

[0012] The extraction filter fabric of this disclosure includes multifilaments included in at least one of the warp or weft threads of the fabric, and monofilaments perpendicular to the multifilaments. Here, the multifilaments only need to be included in at least one of the warp or weft threads of the fabric, and the monofilaments only need to be included in a direction perpendicular to the multifilaments. With this structure, the warp or weft gaps between monofilaments can be covered by the multifilaments perpendicular to them, thereby forming a desirable opening. Multifilaments and monofilaments may be mixed in the warp and / or weft threads, but at least in some parts, the monofilaments and multifilaments are perpendicular to each other. This allows the liquid to be extracted at an optimal rate while preventing the permeation of fine powder and other residues to be removed during extraction (in this disclosure, the objects to be removed by the filter during extraction may be simply referred to as "extraction residues" below). If both the warp and weft threads are monofilaments, the maximum distance between single filaments can be reduced by increasing the density of the fabric, but even with a high-density design that is the limit for stable production, it is difficult to sufficiently prevent the permeation of extraction residues. Furthermore, while using multifilaments in either case reduces voids and prevents the permeation of extraction residue, it also slows down the liquid permeation rate. This not only increases the extraction time compared to paper filters, but also reduces the stiffness and resilience of the fabric, worsening the handling of the filter after molding. Including monofilaments in at least one of the warp or weft threads can improve stiffness, resilience, and moldability.

[0013] In the extraction filter fabric of this disclosure, it is preferable that 90% or more of the number of threads of at least one of the warp or weft threads are multifilaments, and 90% or more of the threads perpendicular to them are monofilaments, more preferably that 90% or more of the weft threads are multifilaments and 90% or more of the warp threads are monofilaments, and even more preferably that 100% of the weft threads are multifilaments and 100% of the warp threads are monofilaments. By adopting these embodiments, a fabric with high production efficiency and stable liquid extraction can be obtained. A preferred embodiment of the extraction filter fabric in this disclosure is that at least one of the warp or weft threads is a multifilament, and the direction perpendicular to the multifilament is monofilament. A more preferred embodiment is that the warp threads are monofilaments and the weft threads are multifilaments. For example, a fabric as shown in the schematic diagram of Figure 1. By adopting these embodiments, the monofilament weft of a mesh fabric can be switched to a multifilament for filter weaving, resulting in excellent productivity and low cost.

[0014] In the extraction filter fabric of this disclosure, the total fineness (T1) of the multifilaments is 80 dtex or more, the total fineness (T2) of the monofilaments is 40 dtex or less, and the ratio of the total fineness (T1 / T2) of the multifilaments to the monofilaments is 2.0 to 5.0. The one with the relatively higher total fineness is used as the multifilament to reduce bending rigidity, and the monofilaments and monofilaments are woven perpendicularly to each other. This suppresses crimp formation of the monofilaments, and if the multifilaments do form crimps, the denser structure better prevents the penetration of extraction residue from both the surface and cross-sectional directions. Since the respective total finenesses and their ratios influence each other, both are set within the above ranges in this disclosure.

[0015] In this disclosure, the total fineness (T1) of the multifilament is 80 dtex or more. If the total fineness of the multifilament is less than 80 dtex, the crimp-forming ability decreases. A preferred total fineness of the multifilament is 100 dtex or more. There is no particular upper limit, but from the viewpoint of ease of processing of the extraction filter, 200 dtex or less is preferred, and 170 dtex or less is more preferred. In addition, the total fineness of the monofilament is 40 dtex or less from the viewpoint of suppressing crimp formation. 36 dtex or less is preferred, and 33 dtex or less is more preferred. There is no particular lower limit, but from the viewpoint of operability and handling during spinning and weaving, 16 dtex or more is preferred.

[0016] Furthermore, the ratio (T1 / T2) of the total fineness of the multifilament (T1) to the total fineness of the monofilament (T2) is between 2.0 and 5.0. If the ratio (T1 / T2) of the total fineness of the multifilament (T1) to the total fineness of the monofilament (T2) is less than 2.0, the voids in the cross-sectional direction of the fabric caused by the crimping of the multifilament widen, and the permeation of the extraction grounds cannot be sufficiently prevented. Also, the bending rigidity of the monofilament increases, resulting in increased stiffness and good dimensional stability, but the molded filter does not conform to the shape of the coffee dripper, reducing its ability to be set in the dripper. In terms of excellent dimensional stability, a ratio of 2.5 or higher is preferable, and 3.0 or higher is more preferable. On the other hand, if it exceeds 5.0, the permeation of the extraction grounds can be prevented, but the stiffness and stiffness decrease, resulting in poor dimensional stability and reduced handling. In terms of further suppressing the permeation of the extraction grounds, a ratio of 4.3 or lower is preferable, and 4.0 or lower is more preferable.

[0017] A multifilament with 10 to 40 filaments is preferable because it allows for voids that further suppress the permeation of extraction residue even when twisting occurs in the single yarns, and also provides excellent handling of the filter after molding. When the number of filaments is preferably 10 or more, more preferably 16 or more, and even more preferably 20 or more, voids can be suppressed even when some single yarns twist due to weaving or post-processing, making it difficult for extraction residue to permeate, and for example, off-flavors in the extracted beverage can also be suppressed. When the number of filaments is preferably 40 or less, more preferably 30 or less, the liquid permeation rate is improved, and a shorter extraction time can be achieved. In addition, since the number of filaments also affects the fineness of the single yarns, setting the number of filaments above the above range also improves the firmness and resilience of the fabric.

[0018] Furthermore, it is preferable that the maximum single-fiber distance (L) of the multifilament be 40 μm or less, as this can better prevent the permeation of extraction residue. It is preferable that the maximum single-fiber distance (L) be 30 μm or less. Keeping it below the above range can further suppress the permeation of extraction residue, leading to the suppression of off-flavors. The lower limit is not particularly limited, but it is preferable to be 10 μm or more from the viewpoint of extraction speed, and more preferable to be 15 μm or more from the viewpoint of ease of fabrication and manufacturing cost. In this disclosure, the maximum single-fiber distance of the multifilament refers to the distance between single filaments constituting the same multifilament, and the distance between multifilaments. Specifically, the maximum single-fiber distance (L) can be determined by the measurement method described in the examples. Using Figure 1, the maximum single-fiber distance (L) corresponds to (1) in Figure 1.

[0019] In the textile for extraction filters of this disclosure, the materials of the multifilaments and monofilaments are not particularly limited, and various materials can be used, such as polyesters and copolymers thereof, including polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid, as well as polyamides such as nylon 6, nylon 66, and nylon 610. Among these, it is preferable to use a thermoplastic polymer that is easy to mold for the extraction filter. Furthermore, it is preferable that the multifilaments and monofilaments are polylactic acid fibers because they are biodegradable and environmentally friendly even when disposable. The polymer of the polylactic acid fiber is -(O-CHCH ３ -CO) ｎ Polylactic acid polymers are polymers that use a repeating unit, and are obtained by polymerizing oligomers of lactic acid such as lactic acid and lactide. Since lactic acid has two optical isomers, D-lactic acid and L-lactic acid, its polymers include poly(D-lactic acid) consisting only of the D-isomer, poly(L-lactic acid) consisting only of the L-isomer, and polylactic acid polymers consisting of both. As the optical purity of D-lactic acid or L-lactic acid in the polylactic acid polymer decreases, the crystallinity decreases and the melting point depression increases. Therefore, it is preferable that the optical purity be 90% or higher in order to improve heat resistance. However, in addition to the system in which the two types of optical isomers are simply mixed as described above, it is more preferable to blend the two types of optical isomers, form them into fibers, and then subject them to high-temperature heat treatment of 140°C or higher to form a stereocomplex in which a racemic crystal can be formed, because this can dramatically increase the melting point.

[0020] Furthermore, from the viewpoint of biomass utilization and biodegradability, it is preferable that the proportion of lactic acid monomers constituting the polylactic acid fibers be 50% by mass or more. Preferably, the proportion of lactic acid monomers constituting the polylactic acid fibers is 75% by mass or more, and more preferably 96% by mass or more. However, components other than lactic acid may be copolymerized within this range, as long as the properties of polylactic acid are not impaired.

[0021] The molecular weight of the polylactic acid polymer is preferably 50,000 or more, more preferably 100,000 or more, in order to achieve a good balance between mechanical properties and moldability. It is also preferably 350,000 or less, and more preferably 250,000 or less. In addition, the polylactic acid fiber polymer may be blended with thermoplastic polymers other than polylactic acid, or composited (core-sheath, bimetal) as needed. Furthermore, modifiers such as matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, antistatic agents, dyeability enhancers, antibacterial agents, flame retardants, and UV absorbers may be added.

[0022] The strength of the multifilaments and monofilaments in this disclosure is preferably 1.8 cN / dtex or higher, more preferably in the range of 2.5 cN / dtex or higher and 4.5 cN / dtex or lower. This range improves process passability in the spinning, false twisting, weaving, and finishing processes. The elongation is preferably 19% or higher, more preferably 25% or higher, and even more preferably 30% or higher. It is also preferably 70% or lower, and even more preferably 60% or lower. This range improves operational stability in subsequent processes during manufacturing. A boiling water shrinkage rate of 30% or lower is practically preferable, allowing for stable quality and operability in subsequent processes. A boiling water shrinkage rate of 25% or lower is even more preferable. While there is no particular lower limit, 5% or higher is preferred. Such adjustments of fineness, strength, elongation, and boiling water shrinkage rate can be performed by conventionally known methods. Furthermore, in this disclosure, strength and elongation are determined in accordance with JIS L 1013 (2010) 8.5.1, and boiling water shrinkage is determined by the value measured in accordance with JIS L 1013 (2010) 8.18.1(a)A method. Specifically, these can be determined by the method described in the examples.

[0023] The cross-sectional shape of the yarn can be round, Y-shaped, T-shaped, flattened, or any other shape that is a further modification of these. Furthermore, the multifilament may be a false-twist crimped yarn.

[0024] The density of the extraction filter fabric according to this disclosure is preferably 90 to 300 threads / 2.54 cm for the warp density, more preferably 100 to 260 threads / 2.54 cm, and preferably 70 to 200 threads / 2.54 cm for the weft density, more preferably 75 to 180 threads / 2.54 cm. When the density is within this range, the permeation of fine particles during coffee extraction can be further suppressed, and the extraction time can also be shortened.

[0025] While there are no particular limitations on the weave structure, plain weave or twill weave is preferred from the viewpoint of preventing fabric slippage, ensuring uniform extraction of beverages, and reducing the amount of yarn used for inexpensive production.

[0026] The extraction filter in this disclosure is made of the extraction filter fabric described herein. The shape is not particularly limited and can be manufactured by cutting the extraction filter fabric into the required shape as appropriate using an ultrasonic welder, high-frequency welder, melt cutting, etc., and treating the edges as necessary. It can also be manufactured by molding. Furthermore, the target of extraction and the application of the extraction filter are not particularly limited, but it can be suitably used for extracting beverages. For example, it can be used to remove coffee grounds and tea leaves that become extraction residue in various teas such as coffee, black tea, and green tea. It can also be used to separate liquids from solids in wine, fruits, vegetables, etc.

[0027] Next, an example of a method for manufacturing the extraction filter fabric of this disclosure will be described.

[0028] The method for manufacturing multifilaments in this disclosure is not particularly limited, and conventionally known methods can be employed. For example, multifilaments using thermoplastic polymers can be obtained by spinning a molten polymer and then, if necessary, performing stretching, false twisting, heat treatment, etc. Monofilaments can be manufactured similarly, but false twisting is not suitable because they are single fibers. The same applies to polylactic acid fibers.

[0029] The obtained multifilaments and monofilaments can be used to weave into a fabric. The loom is not particularly limited and conventionally known methods can be used, but in order to control the maximum single-fiber distance (L) of this disclosure, it is preferable to design the density so that there are not excessive gaps between the multifilaments arranged during weaving, or so that they are not excessively packed and do not cause deflection of the single fibers in the multifilaments. Specifically, if the density is within the preferred range of this disclosure as described above, it becomes easy to achieve the maximum single-fiber distance (L) of this disclosure. In addition, it is also possible to obtain the maximum single-fiber distance (L) by shrinking the multifilaments and monofilaments in the scouring process of the fabric, but in terms of ease of design, it is preferable to process at a low temperature of 30 to 60°C to suppress the shrinkage of the multifilaments and monofilaments, and to minimize the effect of deflection and movement of the single fibers in the multifilaments on the single-fiber distance, so that the maximum single-fiber distance (L) can be obtained as designed. In the heat-setting process of the fabric, it is also preferable to widen the fabric by about 1% in order to suppress the deflection of the entire fabric.

[0030] The textiles of this disclosure will be described in detail below with reference to examples, but this disclosure is not limited to these examples. The evaluations in each example were obtained by the following method.

[0031] [Fineness (dtex)] The fineness of the fibers constituting the fabric was measured in accordance with JIS L 1013 (2010) 8.3.1 (Method B). The official moisture content was assumed to be 0%. The fineness of the yarn before weaving was measured in accordance with JIS L 1013 (2010) 8.3.1 (Method A).

[0032] [Tensile Strength, Elongation] Measured in accordance with JIS L 1013 (2010) 8.5.1 Tensile strength and elongation. The gripping distance was 500 mm and the tensile speed was 500 mm / min. The average value of three repeated measurements was used.

[0033] [Boiling water shrinkage rate] Measured in accordance with JIS L 1013 8.18.1(a) Change rate of skein dimensions (Method A).

[0034] [Weight-average molecular weight] Measured using a Waters 2690 gel permeation chromatograph with polystyrene as the standard.

[0035] [Ratio of total fineness of multifilaments (T1) to total fineness of monofilaments (T2) in the fabric (T1 / T2)] From a fabric that had undergone scouring and dry heat setting, one 20 cm length of multifilament and one 20 cm length of monofilament were taken. One end of each thread was fixed perpendicular to the ground to prevent movement, and a mark was made 3 cm from the end of the thread, then another mark was made 9 cm from that mark, and the thread was cut at the marked points. The weight (g) of the cut thread was measured on a scale, and the approximate fineness (dtex) was calculated by multiplying the weight (g) by 100,000 and 1.11. The applied load (g) was set to 1 / 30 of the approximate fineness. Furthermore, five 20 cm lengths of multifilament and five 20 cm lengths of monofilament were taken, and one end of each thread was fixed perpendicular to the ground to prevent movement. The previously calculated applied load (g) was applied to the unfixed end of the thread to remove the crimp. Then, a mark was made 3 cm from the fixed end of the thread, and another mark was made 9 cm from that mark. The thread was cut at the marked points, and the weight (g) of the cut thread was measured on a scale. The weight (g) was multiplied by 100,000 and 1.11 to obtain the total fineness (dtex). The average value of the five threads was taken as the total fineness of the multifilament (T1) and the total fineness of the monofilament (T2), and T1 / T2 was taken as the ratio of the total fineness. In the comparative example, for the cases where only monofilament or only multifilament was used, the T1 / T2 values ​​were calculated as reference values ​​by assuming, for convenience, that the former was the total fineness of multifilament and the latter was the total fineness of monofilament.

[0036] [Number of filaments in multifilaments in woven fabric] Five 10cm lengths of multifilament were taken from woven fabric that had undergone scouring and dry heat setting. One end of each filament was then fixed to a black cardboard base to prevent movement, and the individual filaments were unraveled using tweezers while observing with a stereomicroscope (manufactured by AS ONE Corporation). The average of the total number of individual filaments counted was taken as the number of filaments.

[0037] [Maximum distance between single filaments in a multifilament (L)] From a fabric that has undergone scouring and dry heat setting, one 30 cm x 30 cm sample was taken from the center of the fabric when the total width of the fabric was divided into three sections in the width direction. Next, the surface of the fabric was observed at a magnification of 300x using a digital microscope "VHX"-500 (manufactured by Keyence Corporation), and one photograph was randomly taken from each sample. In the photograph, five locations where a large gap could be observed between the single filaments constituting one multifilament (all locations if there were no five locations) and five locations where a large gap could be observed between multifilaments (all locations if there were no five locations) were measured, for a total of 10 locations. The maximum distance (μm) in the gap parallel to the direction in which the monofilaments are aligned was measured, and the maximum value among all the maximum distances was defined as the maximum distance between single filaments of the multifilament (L).

[0038] [Filter Permeability in Coffee Extraction] As an index for evaluating the amount of fine powder permeation and permeation time of coffee extract, a simple filter was made by cutting a woven filter material into a fan shape and heat-sealing both ends. Next, the filter was set in a coffee dripper (HARIO Corporation, "V60" permeable coffee dripper VD-01T), and coffee was extracted using finely ground coffee powder with a particle size of approximately 460-540 μm (Sawai Coffee Co., Ltd., Golden Colombia 500g) with 10g of coffee powder per 100ml of water. The following evaluations were performed: ・Amount of fine powder permeation After 3 days, the top layer of the extracted liquid was discarded, leaving only the precipitate. After 7 days, the weight (g) of the precipitate was measured and defined as the amount of fine powder permeation. Furthermore, coffee was extracted using a paper filter material (HRIO Co., Ltd., "V60" paper filter) in the same manner as above. For the amount of fine particles that passed through, it was indicated as ○ if it was within +0.03g of the amount that passed through the paper filter, as indicated as △ if it was between +0.04g and +0.10g of the amount that passed through the paper filter, and as × if it was +0.11g or more of the amount that passed through the paper filter. The amount that passed through the paper filter was 0.2g. ・Passage time The time (in seconds) required for 98ml to pass through was defined as the transmission time. For the transmission time, it was compared with the paper filter in the same manner as above. It was indicated as ○ if it was within ±5 seconds of the paper filter transmission time, as indicated as △ if it was between ±6 seconds and ±15 seconds of the paper filter transmission time, and as × if it was ±16 seconds or more of the paper filter transmission time. The paper filter transmission time was 77 seconds. - Overall Evaluation: A five-level overall evaluation was performed based on a three-level evaluation of the two items above: the amount of fine powder permeation and the permeation time. If both items received a ○ rating, the evaluation was S; if one item received a ○ rating and the other a △ rating, the evaluation was A; if both items received a △ rating, the evaluation was B; if one item received a ○ or △ rating and the other an × rating, the evaluation was C; and if both items received an × rating, the evaluation was D. An S rating and an A rating were considered passing grades.

[0039] [Example 1] Lactide prepared from L-lactic acid with an optical purity of 99.5% was polymerized at 180°C for 180 minutes in a nitrogen atmosphere in the presence of a bis(2-ethylhexanoate)tin catalyst (lactide to catalyst molar ratio = 10000:1) to obtain polylactic acid polymer P1. Polylactic acid polymer P1 with a weight-average molecular weight of 140,000 was melted at 230°C and a yarn was extruded from a spinneret. The yarn was cooled by a cooling device that emitted cooling air from one direction, and a spinning oil was applied by an oiling roller type oiling device. The yarn was heat-treated by winding it on a first Godet roller heated to 104°C and a second Godet roller heated to 115°C at a spinning speed of 3500 m / min, and stretched 3.14 times between the first and second Godet rollers before winding to obtain a 33 dtex polylactic acid monofilament. The boiling water shrinkage rate of the obtained yarn was 21.5%. Furthermore, polylactic acid polymer P2 with a weight-average molecular weight of 190,000 was melted at 220°C, and a yarn was extruded from a spinneret. The yarn was cooled by a cooling device that emitted cooling air from one direction, and a spinning oil was applied using an oiling roller type oiling device. The yarn was spun at a spinning speed of 4500 m / min, wound onto an unheated first Godet roller and an unheated second Godet roller, stretched to 1.01 times its original length between the first and second Godet rollers, and wound up to obtain a polylactic acid multifilament of 106 dtex 26 filaments. The boiling water shrinkage rate of the obtained yarn was 23.5%. The obtained polylactic acid monofilaments were used as warp threads, with one thread per reed, and the obtained polylactic acid multifilaments were used as weft threads to weave a plain weave fabric with a warp density of 110 threads / 2.54 cm and a weft density of 84 threads / 2.54 cm. After scouring in 40°C hot water for 30 seconds, the fabric was dry-heated in a tenter at 120°C for 1 minute to obtain a fabric for extraction filters with a warp density of 112 threads / 2.54 cm and a weft density of 84 threads / 2.54 cm. The physical properties of the polylactic acid monofilaments were a strength of 4.2 cN / dtex and an elongation of 40.5%, while the physical properties of the polylactic acid multifilaments were a strength of 2.9 cN / dtex and an elongation of 54.0%.The resulting fabric consisted of monofilaments forming warp-direction voids between monofilaments, covered by orthogonal multifilaments. The total fineness of the multifilaments (T1) was 117.6 dtex, the total fineness of the monofilaments (T2) was 35.6 dtex, the ratio of total fineness (T1 / T2) was 3.3, the number of multifilaments was 26, and the maximum distance between single filaments (L) was 29 μm. A filter was made using the resulting fabric, and the permeability of the filter material during coffee extraction was measured. The result was a fine powder permeability of 0.21 g and a permeability time of 78 seconds, which is comparable to that of a paper filter, and the filter was judged to be acceptable with an S rating.

[0040] [Example 2] Under the same conditions as in Example 1, a 33dtex polylactic acid monofilament and a 106dtex 26 filament polylactic acid multifilament were obtained. Furthermore, using the 106dtex 26 filament polylactic acid multifilament, false twisting was performed with a draw ratio of 1.45 times, a heater temperature of 115°C, and a friction disc type twister to obtain a false twisted yarn of 84dtex 26 filament. The boiling water shrinkage rate of the obtained yarn was 19.7%. The obtained polylactic acid monofilaments were used as warp threads, and four threads were passed through the reed per dent to obtain the obtained polylactic acid multifilament false twist yarn. Using this as the weft thread, a 2 / 2 twill fabric with a warp density of 254 threads / 2.54 cm and a weft density of 120 threads / 2.54 cm was woven. After scouring in 40°C hot water for 30 seconds, it was dry-heated in a tenter at 120°C for 1 minute to obtain a fabric for extraction filters with a warp density of 255 threads / 2.54 cm and a weft density of 120 threads / 2.54 cm. The physical properties of the above polylactic acid multifilaments were a strength of 1.8 cN / dtex and an elongation of 19.1%. The resulting fabric consisted of monofilaments forming warp-direction voids between monofilaments, covered by orthogonal multifilaments. The total fineness of the multifilaments (T1) was 89.6 dtex, the total fineness of the monofilaments (T2) was 35.1 dtex, the ratio of total fineness (T1 / T2) was 2.6, the number of multifilaments was 26, and the maximum distance between single filaments (L) was 21 μm. A filter was made using the resulting fabric, and the permeability of the filter material during coffee extraction was measured. The result was a fine powder permeability of 0.18 g and a permeability time of 81 seconds, which was comparable to that of a paper filter, and was judged to be acceptable with an S rating. However, the morphological stability was slightly inferior to that of Example 1.

[0041] [Example 3] A 33dtex polylactic acid monofilament was obtained under the same conditions as in Example 1. In addition, a polylactic acid polymer P2 with a weight-average molecular weight of 190,000 was melted at 220°C, and a yarn was extruded from a spinneret. The yarn was cooled by a cooling device that emitted cooling air from one direction, and a spinning oil was applied by an oiling roller type oiling device. The yarn was spun at a spinning speed of 4500 m / min, wound onto an unheated first Godet roller and an unheated second Godet roller, stretched to 1.02 times its original length between the first and second Godet rollers, and wound up to obtain a 106dtex 5-filament polylactic acid multifilament. The boiling water shrinkage rate of the obtained yarn was 24.2%. The obtained polylactic acid monofilaments were used as warp threads, with one thread per reed, and the obtained polylactic acid multifilaments were used as weft threads to weave a plain weave fabric with a warp density of 110 threads / 2.54 cm and a weft density of 84 threads / 2.54 cm. After scouring in 40°C hot water for 30 seconds, the fabric was dry-heated in a tenter at 120°C for 1 minute to obtain a fabric for extraction filters with a warp density of 112 threads / 2.54 cm and a weft density of 84 threads / 2.54 cm. The physical properties of the above polylactic acid multifilaments were a strength of 3.3 cN / dtex and an elongation of 51.0%. The resulting fabric consisted of monofilaments forming warp-direction voids between monofilaments, covered by orthogonal multifilaments. The total fineness of the multifilaments (T1) was 118.7 dtex, the total fineness of the monofilaments (T2) was 35.4 dtex, the ratio of total fineness (T1 / T2) was 3.4, the number of multifilaments was 5, and the maximum distance between single filaments (L) was 31 μm. A filter was made using the resulting fabric, and the permeability of the filter material during coffee extraction was measured. The result was a fine powder permeability of 0.25 g and a permeability time of 72 seconds. Although the fine powder permeability was slightly higher than that of a paper filter, a permeability time similar to that of a paper filter was obtained, and it was judged to be a success with an A rating.

[0042] [Comparative Example 1] A 33dtex polylactic acid monofilament was obtained under the same conditions as in Example 1. In addition, a polylactic acid polymer P2 with a weight-average molecular weight of 190,000 was melted at 220°C, a yarn was extruded from a spinneret, the yarn was cooled by a cooling device that emitted cooling air from one direction, a spinning oil was applied by an oiling roller type oiling device, the yarn was wound at a spinning speed of 4500 m / min on an unheated first Godet roller and an unheated second Godet roller, stretched to 1.01 times between the first and second Godet rollers and wound up, and a 33dtex 10 filament polylactic acid multifilament was obtained. The boiling water shrinkage rate of the obtained yarn was 21.4%. The obtained polylactic acid monofilament was used as the warp thread, and the reed was passed through the reed at a rate of one thread per reed. The resulting polylactic acid multifilament yarn was then used as the weft thread to weave a plain weave fabric with a warp density of 110 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. After scouring in 40°C hot water for 30 seconds, the fabric was dry-heated in a tenter at 120°C for 1 minute to obtain a fabric for extraction filters with a warp density of 111 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. The physical properties of the above polylactic acid multifilament were a strength of 2.8 cN / dtex and an elongation of 55.0%. The resulting fabric consisted of monofilaments forming warp-direction voids between monofilaments, covered by orthogonal multifilaments. The total fineness of the multifilaments (T1) was 35.9 dtex, the total fineness of the monofilaments (T2) was 34.8 dtex, the ratio of total fineness (T1 / T2) was 1.0, the number of multifilaments was 10, and the maximum distance between single filaments (L) was 38 μm. A filter was made using the resulting fabric, and the permeability of the filter material during coffee extraction was measured. The result was a fine powder permeability of 0.28 g and a permeability time of 67 seconds. The fine powder permeability was slightly higher and the permeability time was slightly faster than that of a paper filter, resulting in a B grade and a failure.

[0043] [Comparative Example 2] A 33 dtex polylactic acid monofilament was obtained under the same conditions as in Example 1. The obtained polylactic acid monofilament was used as the warp and weft, and one was inserted per reed and passed through the reed to weave a plain fabric with a warp density of 300 threads / 2.54 cm and a weft density of 300 threads / 2.54 cm. After scouring in warm water at 40 °C for 30 seconds, it was heat-set by dry heat at 120 °C for 1 minute using a tenter to obtain a woven fabric for an extraction filter with a warp density of 302 threads / 2.54 cm and a weft density of 301 threads / 2.54 cm. In the obtained woven fabric, since only monofilaments were used in Comparative Example 2, the value corresponding to T1 was shown as T1 with the total fineness of the warp as a reference value. Assuming that the total fineness of the warp monofilament was 35.3 dtex as T1 and the total fineness of the weft monofilament (T2) was 35.1 dtex, the ratio of the total fineness (T1 / T2) was 1.0. Also, since monofilaments were used, the number of filaments was 1 filament, and the maximum single-filament distance (L) was 47 μm. A filter was fabricated using the obtained woven fabric, and as a result of measuring the filter material permeability in coffee extraction, the amount of fine powder permeated was 0.37 g and the permeation time was 58 seconds. The amount of fine powder permeated was more than that of the paper filter, and the permeation time was shorter, so it was judged as unqualified with a D judgment.

[0044] [Comparative Example 3] A 33dtex polylactic acid monofilament was obtained under the same conditions as in Example 1. In addition, a polylactic acid polymer P2 with a weight-average molecular weight of 190,000 was melted at 220°C, a yarn was extruded from a spinneret, the yarn was cooled by a cooling device that emitted cooling air from one direction, a spinning oil was applied by an oiling roller type oiling device, the yarn was wound at a spinning speed of 4500 m / min on an unheated first Godet roller and an unheated second Godet roller, stretched to 1.01 times between the first and second Godet rollers and wound up, and a 33dtex 5-filament polylactic acid multifilament was obtained. The boiling water shrinkage rate of the obtained yarn was 22.0%. The obtained polylactic acid monofilament was used as the warp thread, and the reed was passed through the reed with one thread per dent. The obtained polylactic acid multifilament yarn was then used as the weft thread to weave a plain weave fabric with a warp density of 110 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. After scouring in 40°C hot water for 30 seconds, the fabric was dry-heated in a tenter at 120°C for 1 minute to obtain a fabric for extraction filters with a warp density of 111 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. The physical properties of the above polylactic acid multifilament were a strength of 2.9 cN / dtex and an elongation of 53.0%. The resulting fabric consisted of monofilaments forming warp-direction voids between monofilaments, covered by orthogonal multifilaments. The total fineness of the multifilaments (T1) was 35.8 dtex, the total fineness of the monofilaments (T2) was 35.0 dtex, the ratio of total fineness (T1 / T2) was 1.0, the number of multifilaments was 5, and the maximum distance between single filaments (L) was 42 μm. A filter was made using the resulting fabric, and the permeability of the filter material during coffee extraction was measured. The result showed a fine powder permeability of 0.33 g and a permeability time of 65 seconds. This was higher than that of a paper filter, and the permeability time was slightly faster, resulting in a C rating and a failure.

[0045] [Comparative Example 4] A 33 dtex polylactic acid multifilament was obtained under the same conditions as in Comparative Example 1. Using this as the warp and weft, one thread was inserted per reed and passed through the reed to weave a plain fabric with a warp density of 110 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. After scouring in warm water at 40°C for 30 seconds, it was heat-set by dry heat at 120°C for 1 minute using a tenter to obtain a woven fabric for an extraction filter with a warp density of 111 threads / 2.54 cm and a weft density of 151 threads / 2.54 cm. In the obtained woven fabric, since Comparative Example 4 uses only multifilaments, a value corresponding to T2 was shown as T2 with the total fineness of the weft as a reference value. Since all are multifilaments, there is no gap between the monofilaments in the warp direction. When the total fineness of the warp multifilaments, 35.2 dtex, was taken as T1, the total fineness of the multifilaments (T2) was 35.0 dtex, the ratio of the total fineness (T1 / T2) was 1.0, the number of filaments of the multifilaments was 10 filaments, and the maximum single-filament distance (L) was 24 μm. A filter was fabricated using the obtained woven fabric, and as a result of measuring the filter material permeability in coffee extraction, the amount of fine powder permeated was 0.20 g and the permeation time was 95 seconds, obtaining a fine powder permeation amount comparable to that of a paper filter, but the permeation time was fast and it was judged as不合格 (failed) as a C judgment.

[0046]

[0047] 1: Maximum single-filament distance (L) 2: Weft multifilament in the woven fabric 3: Warp monofilament in the woven fabric

Claims

1. A fabric for extraction filters, comprising multifilaments included in at least one of the warp or weft threads of the fabric, and monofilaments perpendicular to the multifilaments, wherein the total fineness (T1) of the multifilaments is 80 dtex or more, the total fineness (T2) of the monofilaments is 40 dtex or less, and the ratio (T1 / T2) of the total fineness (T1) of the multifilaments to the total fineness (T2) of the monofilaments is 2.0 to 5.

0.

2. The extraction filter fabric according to claim 1, wherein the number of filaments in the multifilament is 10 to 40.

3. The fabric for extraction filters according to claim 1 or 2, wherein the maximum distance (L) between single filaments of the multifilament is 40 μm or less.

4. The extraction filter fabric according to claim 1 or 2, wherein the multifilament and monofilament are polylactic acid fibers.

5. The fabric for extraction filters according to claim 1 or 2, wherein the warp threads are monofilaments and the weft threads are multifilaments.

6. An extraction filter comprising the textile for extraction filters according to claim 1 or 2.

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