Filter for dripping coffee, and coffee drip bag

Abstract

Provided is a filter for dripping coffee, capable of preventing a change in taste of coffee obtained by extraction between immediately after filling of coffee powder and after storage.　Provided is a filter (1) for dripping coffee, in which a first unwoven fabric layer (3) and a second unwoven fabric layer (5) are stacked, wherein the first unwoven fabric layer (3) has hydrophobicity and comes into contact with coffee powder; the second unwoven fabric layer (5) does not have hydrophobicity; and the first unwoven fabric layer (3) has an apparent density of 0.20 g / cm3 or more and has a basis weight of 5-15 g / m2.

Description

Coffee drip filters and coffee drip bags

[0001] The present invention relates to a coffee drip filter for brewing coffee by dripping, and a coffee drip bag formed from the coffee drip filter.

[0002] Conventionally, coffee drip bags have been used to easily drip, for example, a single cup of coffee. A coffee drip bag typically includes a bag-shaped coffee drip filter, a bag body filled with ground coffee, and a latch attached to the bag body for latching onto the top of a cup. The bag body filled with ground coffee is sealed and has perforations for easy opening. By tearing the perforation, latching the latch onto the top of a cup, and pouring hot water over the ground coffee, the hot water comes into contact with the ground coffee, extracting the coffee components. The extracted liquid then passes through the coffee drip filter and drips into the cup.

[0003] One proposed coffee drip filter of this type comprises a first inner nonwoven fabric layer that comes into contact with coffee grounds and a second outer nonwoven fabric layer that are laminated together, with the hydrophobic fiber ratio, porosity, and basis weight (basis weight) of each layer set within specific ranges, the porosity of the first nonwoven fabric layer set to be greater than the porosity of the second nonwoven fabric layer, and the total basis weight set within a specific range (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2002-102070

[0005] In the coffee drip bag using the coffee drip filter of Patent Document 1, the time from pouring hot water onto coffee grounds until the first drop of extract drips from the coffee drip filter (steaming time) is set to an appropriate time, and by appropriately extracting the coffee components from the coffee grounds during this time, it is possible to obtain coffee with excellent taste and aroma.

[0006] However, after a certain period of time (hereinafter referred to as "after storage") has passed with coffee grounds filled inside the coffee drip filter, oil present on the surface of the coffee grounds adheres to the hydrophobic fibers of the first nonwoven fabric layer and penetrates into the first nonwoven fabric layer as the storage period continues. At this time, the amphipathic substances contained in the oil of the coffee grounds are adsorbed by the hydrophobic fibers with their hydrophilic groups facing outward and their hydrophobic groups facing the hydrophobic fibers, thereby reducing the hydrophobicity of the first nonwoven fabric layer. In other words, the adhesion of the oil reduces the hydrophobicity of the surface of the hydrophobic fibers (i.e., increases their hydrophilicity). As a result, the extraction time after storage significantly changes compared to immediately after filling with coffee grounds (hereinafter referred to as "immediately after filling"), resulting in a problem of differences in the taste of the extracted coffee.

[0007] Furthermore, since such coffee drip bags are manufactured, distributed through various channels, and then sold to consumers in stores, there is a large variation in the time between their manufacture and their use by consumers. As a result, the taste of the extracted coffee may change immediately after filling and after storage, and the coffee may not have a consistent taste.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a coffee drip filter that can suppress changes in the taste of coffee obtained by brewing immediately after filling with coffee powder and after storage. Another aim is to provide a coffee drip bag that is made by manufacturing the coffee drip filter into a bag and filling it with coffee powder.

[0009] In order to solve the above problems, the inventors conducted extensive research and discovered that in order to reduce the difference (change) in the taste of coffee obtained by extraction between immediately after filling the coffee powder and after storage, it is necessary to reduce the difference in the time (extraction time) from pouring hot water over the coffee powder until almost all of the extract drips from the coffee drip filter. Furthermore, even if the extraction time is the same, if the time until the first drop of extract drips (steaming time) is insufficient, the taste of the extracted coffee will change, so it is also necessary to ensure a certain amount of steaming time.

[0010] The inventors then discovered that by designing the first nonwoven fabric layer in a coffee drip filter that comes into contact with the coffee grounds as an inner layer having hydrophobic properties and the second nonwoven fabric layer that does not come into contact with the coffee grounds as an outer layer that does not have hydrophobic properties, and by appropriately setting the apparent density and basis weight of the first nonwoven fabric layer, it is possible to suppress changes in extraction time (reduce the difference) between immediately after filling and after storage, and to ensure a steaming time of at least a certain length of time. They also discovered that the coffee drip filter can be reinforced by laminating the first nonwoven fabric layer and the second nonwoven fabric layer, and thus completed the present invention.

[0011] That is, the characteristic configuration of the coffee drip filter according to the present invention for solving the above-mentioned problems is a coffee drip filter including a first nonwoven fabric layer having hydrophobicity and contacting coffee grounds, and a second nonwoven fabric layer having no hydrophobicity, the first nonwoven fabric layer having an apparent density of 0.20 g / cm ３ or more, and the basis weight is 5 to 15 g / m ２ The reason is that...

[0012] According to the coffee drip filter of this configuration, the first nonwoven fabric layer and the second nonwoven fabric layer are laminated, so that the strength of the first nonwoven fabric layer can be supplemented (reinforced) by the second nonwoven fabric layer, thereby increasing the strength of the coffee drip filter. The first nonwoven fabric layer that comes into contact with the coffee grounds is hydrophobic, and the second nonwoven fabric layer that does not come into contact with the coffee grounds is not hydrophobic. The apparent density of the first nonwoven fabric layer is 0.20 g / cm. ３ Or more, basis weight is 5 to 15 g / m ２ By setting this value, it is possible to appropriately adjust the time it takes for the extract to pass through the first nonwoven fabric layer when hot water is poured onto the coffee grounds immediately after filling (before storage) and after storage, thereby making it possible to appropriately set the extraction time and steaming time.As a result, it is possible to suppress changes in the extraction time immediately after filling and after storage, and to ensure a steaming time of at least a certain length, thereby suppressing changes in the taste of the coffee obtained by extraction.

[0013] In the coffee drip filter according to the present invention, it is preferable that the first nonwoven fabric layer has a thickness of 75 μm or less.

[0014] With the coffee drip filter of this configuration, by setting the thickness of the first nonwoven fabric layer within the above-mentioned appropriate range, it is possible to more appropriately adjust the time it takes for the extract to pass through the first nonwoven fabric layer when hot water is poured over the coffee powder immediately after filling and after storage.This makes it possible to more appropriately suppress changes in extraction time between immediately after filling and after storage, and to more appropriately ensure a steeping time of at least a certain length of time.

[0015] In the coffee drip filter according to the present invention, the material constituting the first nonwoven fabric layer is preferably a polyolefin resin.

[0016] According to the coffee drip filter of this configuration, by selecting the above-mentioned appropriate resin as the material for the first nonwoven fabric layer, the first nonwoven fabric layer has hydrophobicity suitable for ensuring a certain or longer steeping time.

[0017] In the coffee drip filter according to the present invention, the first nonwoven fabric layer is preferably a melt-blown nonwoven fabric layer.

[0018] In the coffee drip filter of this configuration, the first nonwoven fabric layer is a meltblown nonwoven fabric layer, which is made up of relatively thin overlapping fibers, and the fibers are fused together at their contact points, resulting in narrow spacing between the fibers, which increases the surface area of ​​the fibers contained in the first nonwoven fabric layer and makes the hydrophobic function of the first nonwoven fabric layer more efficient.

[0019] In the coffee drip filter according to the present invention, the material constituting the second nonwoven fabric layer is preferably a resin containing polyester.

[0020] In the coffee drip filter of this configuration, by selecting the above-mentioned appropriate resin for the second nonwoven fabric layer, the extract that has passed through the first nonwoven fabric layer can pass through the second nonwoven fabric layer in a shorter time than the time it takes for the extract to pass through the first nonwoven fabric layer. As a result, the extraction time and steaming time in the first nonwoven fabric layer are less affected by the second nonwoven fabric layer, which results in more appropriately suppressing the change in extraction time between immediately after filling and after storage, and more appropriately ensuring a steaming time of at least a certain length.

[0021] In the coffee drip filter according to the present invention, the second nonwoven fabric layer is preferably made of short fibers.

[0022] Coffee drip bags made using coffee drip filters are generally opened by cutting off the upper edge along a perforation at the top of the bag. If the second nonwoven fabric layer is made of long fibers, the perforation is difficult to tear and may produce fuzz when torn. However, with the coffee drip filter of this configuration, short fibers are selected as the fibers constituting the second nonwoven fabric layer, making the perforation easier to tear and reducing the generation of fuzz when torn.

[0023] In the coffee drip filter according to the present invention, the second nonwoven fabric layer is preferably a wet-laid nonwoven fabric layer.

[0024] In the coffee drip filter of this configuration, by selecting a wet-laid nonwoven fabric layer as the second nonwoven fabric layer, the fibers constituting the second nonwoven fabric layer can be more uniformly dispersed throughout the second nonwoven fabric layer, which prevents the perforations from being locally difficult to tear, making the perforations easier to tear.

[0025] In the coffee drip filter according to the present invention, the melt-blown nonwoven fabric layer is preferably an assembly of fibers formed by melting a hydrophobic resin into fibers by a melt-blowing method and directly laminating the fibers on the second nonwoven fabric layer.

[0026] In the coffee drip filter having this configuration, the melt-blown nonwoven fabric layer serving as the first nonwoven fabric layer is an aggregate of fibers formed by melt-blowing a molten hydrophobic resin into fibers and then laminating the fibers directly onto the second nonwoven fabric layer. This allows the first nonwoven fabric layer to be laminated onto the second nonwoven fabric layer by an anchoring effect, and the apparent density and basis weight of the first nonwoven fabric layer can be appropriately set within the above-mentioned ranges.

[0027] Another feature of the coffee drip bag according to the present invention for solving the above-mentioned problems is that the coffee drip bag is made by forming the above-mentioned coffee drip filter into a bag, and the bag body is formed into a bag shape with the first nonwoven fabric layer located inside, a cup latch attached to the bag body, and coffee powder filled in the bag body.

[0028] The coffee drip bag of this configuration allows you to drip coffee into a cup by attaching the cup latch to the cup and pouring hot water over the coffee powder packed in the bag body. The coffee drip filter prevents any change in extraction time between immediately after filling and after storage, and also ensures a certain amount of steeping time, thereby preventing any change in the taste of the extracted coffee.

[0029] Fig. 1 is a cross-sectional view schematically showing a cross section of a coffee drip filter according to one embodiment of the present invention. Fig. 2 is a schematic perspective view showing an example of a coffee drip bag obtained by manufacturing the coffee drip filter according to this embodiment. Fig. 3 is a schematic view illustrating a method for measuring a 45° inclined flow length. Fig. 4 is a scanning microscope photograph illustrating an example of a method for measuring the thickness of a first nonwoven fabric layer.

[0030] Hereinafter, embodiments of the coffee drip filter and the coffee drip bag according to the present invention will be described in detail. However, the present invention is not intended to be limited to the configurations described below.

[0031] [Coffee Drip Filter] Fig. 1 is a cross-sectional view schematically illustrating a coffee drip filter 1 according to one embodiment of the present invention. In Fig. 1, the layer structure constituting the coffee drip filter 1 is enlarged to facilitate understanding of the invention, but the size relationships (size relationships) of the layers do not necessarily reflect the size relationships in the actual layer structure. The coffee drip filter 1 of this embodiment is formed by laminating a first nonwoven fabric layer 3 having hydrophobic properties and a second nonwoven fabric layer 5 having no hydrophobic properties. Thus, the first nonwoven fabric layer 3 and the second nonwoven fabric layer 5 have different configurations.

[0032] Here, "hydrophobicity" can be determined by a 45° inclined flow length test. Specifically, as shown in FIG. 3, 10 sheets of toilet paper (an example of a water-absorbent sheet) are stacked on an inclined surface at an angle of 45° to the horizontal plane and secured with an absorbent paper fastener such as adhesive tape. A nonwoven fabric (or nonwoven fabric layer) is then placed on top of the absorbent paper as a measurement sample and secured with a measurement sample fastener such as adhesive tape. Next, using a 5 mL Komagome pipette, a single drop of water (0.035 mL) is dropped from a height of 10 mm onto the surface (top surface) of the measurement sample, and the distance (length of the trajectory) that the drop slides downward along the top surface of the measurement sample is measured. More specifically, a mark is made on the nonwoven fabric with a ballpoint pen or the like, a drop of water is dropped on the mark as described above, and the distance from the mark to the bottom edge of the drop that slides downward is measured. In this way, the sliding distance is measured at 10 random locations, the average is calculated, and the resulting average is designated as the 45° inclined flow length (45° inclined flow length test). Furthermore, when the 45° inclined flow length is 10 cm or more, it is considered to be "hydrophobic," and when it is less than 10 cm, it is considered to be "not hydrophobic." "Not hydrophobic" also includes embodiments where the nonwoven fabric has hydrophilic properties. When a laminate of a first nonwoven fabric layer and a second nonwoven fabric layer is used as a measurement sample, the 45° inclined flow length of the first nonwoven fabric layer can be measured when the laminate is fixed so that the second nonwoven fabric layer is in contact with absorbent paper and the first nonwoven fabric layer is on the upper surface, while the 45° inclined flow length of the second nonwoven fabric layer can be measured when the laminate is fixed so that the first nonwoven fabric layer is in contact with absorbent paper and the second nonwoven fabric layer is on the upper surface.

[0033] The first nonwoven fabric layer 3 is hydrophobic. That is, the first nonwoven fabric layer 3 has a 45° inclination flow length of 10 cm or more. When the coffee drip filter 1 is used, the first nonwoven fabric layer 3 is placed on the side that comes into direct contact with coffee grounds. The apparent density and basis weight of the first nonwoven fabric layer 3 are set so as to suppress changes in extraction time between immediately after filling and after storage, and to ensure a certain or longer steeping time.

[0034] The first nonwoven fabric layer 3 has an apparent density of 0.20 g / cm ３ By setting the apparent density of the first nonwoven fabric layer 3 to the above lower limit or higher, the voids contained in the first nonwoven fabric layer 3 can be appropriately reduced, and this, combined with the basis weight described below, makes it possible to appropriately adjust the time it takes for the extract to pass through the first nonwoven fabric layer 3 when hot water is poured onto the coffee powder immediately after filling and after storage, thereby making it possible to appropriately set the steaming time and extraction time. As a result, it is possible to suppress changes in extraction time immediately after filling and after storage, and to ensure a steaming time of at least a certain length of time, thereby suppressing changes in the taste of the coffee obtained by extraction. The first nonwoven fabric layer 3 has an apparent density of 0.60 g / cm or higher. ３ It is preferable to set it to 0.50 g / cm or less. ３ It is more preferable to set it to 0.35 g / cm or less. ３ It is more preferable that the apparent density of the first nonwoven fabric layer 3 is set to be equal to or less than the above upper limit. By setting the apparent density of the first nonwoven fabric layer 3 to be equal to or less than the above upper limit, it is possible to prevent the amount of voids from becoming too small and the steaming time from becoming too long. The apparent density can be measured by the measurement method described below.

[0035] The first nonwoven fabric layer 3 has a basis weight of 5 to 15 g / m ２is set to. By setting the basis weight of the first nonwoven fabric layer 3 within the above-mentioned appropriate range, the thickness of the first nonwoven fabric layer 3 can be made appropriate. This, combined with the apparent density described above, makes it possible to appropriately adjust the time it takes for the extract to pass through the first nonwoven fabric layer 3 when hot water is poured onto the coffee powder immediately after filling and after storage. This allows the steaming time and extraction time to be set appropriately. As a result, it is possible to suppress changes in extraction time between immediately after filling and after storage, ensure a steaming time of at least a certain length, and suppress changes in the taste of the coffee obtained by extraction. Also, from the perspective of cost reduction, it is preferable to set the basis weight of the first nonwoven fabric layer 3 to be equal to or less than the above-mentioned upper limit. The basis weight of the first nonwoven fabric layer 3 can be measured using the measurement method described below.

[0036] A second nonwoven fabric layer 5, which will be described later, is laminated on the first nonwoven fabric layer 3. The second nonwoven fabric layer 5 supplements (reinforces) the strength of the first nonwoven fabric layer 3. By laminating the first nonwoven fabric layer 3 and the second nonwoven fabric layer 5, the strength of the first nonwoven fabric layer 3 can be supplemented (reinforced) by the second nonwoven fabric layer 5, thereby increasing the strength of the coffee drip filter 1.

[0037] The first nonwoven fabric layer 3 and the second nonwoven fabric layer 5 can be laminated by a known method. For example, they may be laminated by spraying, or the two nonwoven fabrics may be laminated by overlapping the respective nonwoven fabrics produced separately and then subjecting them to a full-surface thermocompression treatment using a calendar roll or a partial thermocompression treatment using an embossing roll or the like. Among these, in order to set the apparent density and basis weight of the first nonwoven fabric layer 3 within the above ranges, the first nonwoven fabric layer 3 is preferably a meltblown nonwoven fabric layer. The meltblown nonwoven fabric layer is preferably an assembly of fibers formed by spraying a molten hydrophobic resin onto the second nonwoven fabric layer 5 using a meltblowing (MB) method, and then laminating the layer on the second nonwoven fabric layer 5. In other words, the meltblown nonwoven fabric layer is preferably an assembly of fibers formed by fiberizing the molten hydrophobic resin using the meltblowing method and directly laminating the layer on the second nonwoven fabric layer 5.

[0038] When producing nonwoven fabrics (MB nonwoven fabrics) using the melt-blowing method, molten hydrophobic resin is typically sprayed onto a belt conveyor with ventilation holes to accumulate the hydrophobic resin. During this process, the hydrophobic resin is suctioned through the belt conveyor to prevent the accumulated hydrophobic resin from scattering. However, when spraying molten hydrophobic resin onto the second nonwoven fabric layer 5 to accumulate the layer, the second nonwoven fabric layer 5 has a smaller porosity than the belt conveyor, requiring stronger suction force. Therefore, when the first nonwoven fabric layer 3 is accumulated by spraying molten hydrophobic resin using the melt-blowing method and then laminated onto the second nonwoven fabric layer 5, the first nonwoven fabric layer 3 is denser with fewer voids than when nonwoven fabrics are laminated together by embossing and compression bonding. As a result, the apparent density of the first nonwoven fabric layer 3 can be increased compared to when the nonwoven fabrics are embossed and compression bonded, and can be set within the appropriate range. Furthermore, by adjusting the amount of hydrophobic resin accumulated, the thickness of the first nonwoven fabric layer 3 can be adjusted, and the basis weight can be set within the appropriate range. Furthermore, the first nonwoven fabric layer 3 can be laminated to the second nonwoven fabric layer 5 by the anchor effect.

[0039] When the first nonwoven fabric layer 3 is a meltblown nonwoven fabric layer, the layer is made of relatively thin overlapping fibers, and the fibers are fused together at their contact points, resulting in narrow spacing between the fibers. This increases the surface area of ​​the fibers contained in the first nonwoven fabric layer 3, making the hydrophobic function of the first nonwoven fabric layer 3 more efficient. Furthermore, if the meltblown nonwoven fabric layer is laminated to the second nonwoven fabric layer 5 by spraying a molten hydrophobic resin onto the layer using a meltblowing method and then accumulating the fibers, i.e., if the meltblown nonwoven fabric layer is an assembly of fibers in which the molten hydrophobic resin is meltblown into fibers and then directly laminated to the second nonwoven fabric layer 5, the anchor effect allows the first nonwoven fabric layer 3 to be properly laminated to the second nonwoven fabric layer 5, and the apparent density and basis weight of the first nonwoven fabric layer 3 can be set within more appropriate ranges.

[0040] The thickness of the first nonwoven fabric layer 3 is preferably 75 μm or less, more preferably 55 μm or less, and even more preferably 40 μm or less. Setting the thickness of the first nonwoven fabric layer 3 within the above appropriate range allows for more appropriate adjustment of the time it takes for the extract to pass through the first nonwoven fabric layer 3 when hot water is poured over the coffee grounds immediately after filling and after storage. This more appropriately reduces the change in extraction time between immediately after filling and after storage, and more appropriately ensures a certain amount of steeping time or more. The lower limit of the thickness of the first nonwoven fabric layer 3 is not particularly limited as long as the first nonwoven fabric layer 3 can perform its function, but a thickness of 10 μm or more is preferred from the perspective of maintaining the strength of the filter. The thickness of the first nonwoven fabric layer 3 can be measured using the measurement method described below.

[0041] The diameter of the hydrophobic resin fibers constituting the first nonwoven fabric layer 3 is preferably 0.3 to 10 μm, and more preferably 2 to 6 μm. Here, as the fiber diameter increases, the surface area of ​​the first nonwoven fabric layer 3 decreases, shortening the time it takes for the extract to pass through the first nonwoven fabric layer 3. On the other hand, as the fiber diameter decreases, the surface area of ​​the first nonwoven fabric layer 3 increases, lengthening the time it takes for the extract to pass through the first nonwoven fabric layer 3. In this regard, by setting the fiber diameter within the above appropriate range, the time it takes for the extract to pass through the first nonwoven fabric layer 3 can be made more appropriate.

[0042] The material constituting the first nonwoven fabric layer 3 (the material of the fibers made of hydrophobic resin) is preferably a polyolefin resin. Suitable polyolefins include polyethylene, polypropylene, and ethylene-propylene copolymers. By selecting an appropriate resin as the material constituting the first nonwoven fabric layer 3, the first nonwoven fabric layer 3 has hydrophobicity suitable for ensuring a certain or longer steeping time. This allows the time it takes for the extracted liquid to pass through the first nonwoven fabric layer 3 when hot water is poured onto the coffee powder immediately after filling and after storage to be more appropriately adjusted. This more appropriately reduces the change in extraction time between immediately after filling and after storage, and more appropriately ensures a certain or longer steeping time.

[0043] The second nonwoven fabric layer 5 does not have hydrophobic properties. That is, the second nonwoven fabric layer 5 has a 45° inclination flow length of less than 10 cm. The second nonwoven fabric layer 5 does not have hydrophobic properties, can reinforce the first nonwoven fabric layer 3, and does not interfere with the first nonwoven fabric layer 3's suppression of the change in extraction time between immediately after filling and after storage, and with ensuring the steaming time, and may be configured as appropriate as long as such.

[0044] The material constituting the second nonwoven fabric layer 5 is preferably a resin containing polyester, and more preferably a resin containing polyester and polyolefin. Polyethylene terephthalate is suitably selected as the polyester. Polyethylene, polypropylene, and ethylene-propylene copolymers are suitably selected as the polyolefin. The weight ratio of polyester to polyolefin is preferably 7:3 to 9:1. By selecting the above-described appropriate resin as the material constituting the second nonwoven fabric layer 5 and setting the above-described appropriate weight ratio, the extract that has passed through the first nonwoven fabric layer 3 can pass through the second nonwoven fabric layer 5 in a shorter time than the time it takes for the extract to pass through the first nonwoven fabric layer 3. This makes the extraction time and steaming time in the first nonwoven fabric layer 3 less susceptible to the influence of the second nonwoven fabric layer 5. As a result, the change in extraction time between immediately after filling and after storage can be more suitably suppressed, and a steaming time of at least a certain length can be more suitably ensured.

[0045] The second nonwoven fabric layer 5 is preferably composed of short fibers. In this specification, short fibers refer to fibers with a fiber length of 0.1 to 10 mm. A coffee drip bag formed using the coffee drip filter 1 is generally opened by cutting off the upper end along a perforation (not shown) at the top of the coffee drip bag. If the second nonwoven fabric layer 5 is made of long fibers, the perforation will be difficult to tear and may generate fluff when torn. However, by selecting short fibers as the fibers constituting the second nonwoven fabric layer 5, the perforation will be easy to tear and fluffing when torn can be suppressed.

[0046] The second nonwoven fabric layer 5 is preferably a wetlaid nonwoven fabric layer. By selecting a wetlaid nonwoven fabric layer as the second nonwoven fabric layer 5, the fibers constituting the second nonwoven fabric layer 5 can be more uniformly dispersed throughout the second nonwoven fabric layer 5. As a result, the occurrence of localized areas that are difficult to tear along the perforations can be suppressed, making the perforations easier to tear. In this case, the wetlaid nonwoven fabric layer is preferably composed of staple fibers. By selecting a wetlaid nonwoven fabric layer composed of staple fibers as the second nonwoven fabric layer 5, the staple fibers constituting the second nonwoven fabric layer 5 can be more uniformly dispersed throughout the second nonwoven fabric layer 5. As a result, the occurrence of localized areas that are difficult to tear along the perforations can be suppressed, making the perforations easier to tear.

[0047] The second nonwoven fabric layer 5 has a basis weight of 10 to 30 g / m ２ It is preferable that the density is 12 to 25 g / m ２ It is more preferable that the second nonwoven fabric layer 5 has a thickness of 30 to 100 μm, and more preferably 40 to 80 μm. By setting the basis weight and thickness of the second nonwoven fabric layer 5 within the above appropriate ranges, the strength of the coffee drip filter 1 can be appropriately increased. Furthermore, since the time it takes for the extract to pass through the second nonwoven fabric layer 5 can be appropriately shortened compared to the time it takes for the extract to pass through the first nonwoven fabric layer 3, the extraction time and steaming time in the first nonwoven fabric layer 3 are less affected by the second nonwoven fabric layer 5. The basis weight and thickness of the second nonwoven fabric layer 5 can be measured in the same manner as the method for measuring the basis weight and thickness of the first nonwoven fabric layer, which will be described later.

[0048] The diameter of the fibers constituting the second nonwoven fabric layer 5 may be appropriately set so as to appropriately increase the strength of the coffee drip filter 1 and to appropriately shorten the time it takes for the extract to pass through the second nonwoven fabric layer 5 compared to the time it takes for the extract to pass through the first nonwoven fabric layer 3.

[0049] Incidentally, the coffee drip filter 1 is preferably configured such that the average value of the flow length is 10 cm or more for the first nonwoven fabric layer 3, which serves as the inner layer, and the second nonwoven fabric layer 5, which serves as the outer layer, laminated together, and the 45° inclined flow length test is carried out by the following steps (1) to (6): (1) attaching a water-absorbent sheet to an inclined surface inclined at 45° with respect to the horizontal; (2) placing the test cloth on the water-absorbent sheet; (3) dropping a drop of water onto the cloth from a position 10 mm above; (4) leaving it until the water droplet stops flowing; (5) measuring the length of the trajectory of the water droplet (flow length); and (6) performing the above steps (1) to (5) at 10 different points on the cloth to calculate the average value of the flow length.

[0050] This coffee drip filter 1 includes a first nonwoven fabric layer 3 that serves as an inner layer in contact with the coffee grounds and a second nonwoven fabric layer 5 that serves as an outer layer that does not contact the coffee grounds. This allows the strength of the first nonwoven fabric layer 3 to be reinforced by the second nonwoven fabric layer 5, thereby increasing the strength of the coffee drip filter 1. Furthermore, in the 45° inclined flow length test, a flow length of 10 cm or greater is considered to be hydrophobic, while a flow length of less than 10 cm is considered to be non-hydrophobic. Therefore, the first nonwoven fabric layer 3 that serves as the inner layer is a hydrophobic nonwoven fabric layer, and the second nonwoven fabric layer 5 that serves as the outer layer is not hydrophobic. As a result, when hot water is poured onto the coffee grounds immediately after filling and after storage, the first nonwoven fabric layer 3 can appropriately adjust the time it takes for the extract to pass through the first nonwoven fabric layer 3, thereby ensuring a suitable steeping time of at least a certain length. Furthermore, the extract that has passed through the first nonwoven fabric layer 3 can pass through the second nonwoven fabric layer 5 in a shorter time than the time it takes to pass through the first nonwoven fabric layer 3. As a result, the extraction time and steaming time in the first nonwoven fabric layer 3 are less affected by the second nonwoven fabric layer 5, which more appropriately suppresses changes in extraction time between immediately after filling and after storage, and more appropriately ensures a steaming time of at least a certain length of time.

[0051] [Method for manufacturing a coffee drip filter] The coffee drip filter 1 can be manufactured by the following method: (1) A molten hydrophobic resin is sprayed and accumulated by a melt-blowing method onto a second nonwoven fabric layer 5 formed by a wet method or a spunbonding method, thereby forming a first nonwoven fabric layer 3, which is then wound into a roll. (2) The rolled laminate consisting of the first nonwoven fabric layer 3 and the second nonwoven fabric layer 5 is cut to a desired size while being unwound.

[0052] According to the manufacturing method of the coffee drip filter 1 of this embodiment, the first nonwoven fabric layer 3 is firmly laminated to the second nonwoven fabric layer 5 by the anchor effect, so that a coffee drip filter 1 having sufficient strength can be obtained. In addition, the apparent density and basis weight of the first nonwoven fabric layer 3 can be set within appropriate ranges.

[0053] [Coffee Drip Bag] Fig. 2 is a schematic perspective view showing an example of a coffee drip bag 10 obtained by forming a bag using the coffee drip filter of this embodiment. In the coffee drip bag 10 of this embodiment, the coffee drip filter 1 shown in Fig. 1 is formed into a bag shape so that the first nonwoven fabric layer 3 is located inside and the second nonwoven fabric layer 5 is located outside, thereby forming a bag body 11. A cup locking part 13 for locking onto the top of a cup 17 is attached to the bag body 11. A cup of ground coffee 15 for one cup is enclosed in the bag body 11. It is preferable to form a perforation (not shown) at the top of the bag body 11 for opening. The cup locking part 13 can be formed from paperboard or the like having a resin-laminated surface.

[0054] When brewing coffee, the perforation of the bag body 11 of the coffee drip bag 10 is torn, the cup latch 13 is opened to latch onto the cup 17, and hot water is poured onto the coffee powder 15 packed in the bag body 11, thereby dripping the extracted liquid containing the coffee components into the cup 17. In this case, the above-mentioned coffee drip filter 1 can suppress the change in extraction time between immediately after filling and after storage, and can ensure a certain amount of steeping time or more, thereby suppressing changes in the taste of the extracted coffee.

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0056] First, the methods for measuring the basis weight, thickness, and apparent density of the nonwoven fabric layer will be described below.

[0057] (1) Weight (g / m ２ ) In accordance with JIS L-1906, before laminating the first nonwoven fabric layer on the second nonwoven fabric layer, a 10 cm square test piece (area: 0.01 m) was cut from the second nonwoven fabric layer. ２ ) was collected, its mass (g) was measured, and the measurement result was used to calculate the basis weight (g / m ２ Similarly, after laminating the first nonwoven fabric layer on the second nonwoven fabric layer, the basis weight (g / m ２ ) was calculated, and the basis weight of the second nonwoven fabric layer was subtracted from the basis weight of the laminate to obtain the basis weight (g / m ２ ) was calculated.

[0058] (2) Thickness (μm) of First Nonwoven Fabric Layer (i) A laminate of the first and second nonwoven fabric layers was cut into 1 cm squares using an unused razor blade so that a cross section perpendicular to the thickness direction could be observed, and small sample pieces (test pieces) were collected. (ii) The cross sections of the collected small sample pieces were photographed at 450x magnification using a scanning electron microscope (Keyence Corporation, "VHX-D500"). (iii) The thickness of the first nonwoven fabric layer was measured at five random locations on each photograph. An example of measurements at five random locations is shown in Figure 4. (iv) The above steps (i) to (iii) were repeated four times to measure the thickness of the first nonwoven fabric layer at a total of 20 locations, and the average value (μm) was calculated. (v) The average thickness value of the first nonwoven fabric layer obtained in (iv) above was rounded to two decimal places, and the resulting value was designated the thickness (μm) of the first nonwoven fabric layer.

[0059] (3) Apparent density (g / cm) of the first nonwoven fabric layer ３ ) The basis weight (g / m) of the first nonwoven fabric layer obtained in (1) above ２ ) by the thickness (μm) of the first nonwoven fabric layer obtained in (2) above, and the obtained value was used as the apparent density (g / cm ３ )

[0060] Next, the preparation of the first nonwoven fabric layer, the second nonwoven fabric layer, the coffee drip filter, and the coffee drip bag will be described, and the evaluation of the coffee drip bag will be described.

[0061] [Second Nonwoven Fabric Layer] <Examples 1 to 9, Comparative Examples 1 to 6: Wet-laid Nonwoven Fabrics> Using a wet method, fibers composed of polypropylene, polyethylene terephthalate, and an ethylene-propylene copolymer and having an average fiber diameter (diameter) of 8.9 μm were used, and the fibers were fused together by calendaring to form a web so as to obtain the basis weight shown in Tables 1 and 2, thereby obtaining the second nonwoven fabric layers of Examples 1 to 9 and Comparative Examples 1 to 6.

[0062] Example 10: Spunbonded nonwoven fabric Heated and melted polyethylene terephthalate was extruded through a spinning nozzle to form fibers, and the fibrous resin was cooled while being drawn using an ejector at a spinning speed of 5,000 m / min to form long fibers with an average fiber diameter (diameter) of 13.6 μm. The long fibers were then accumulated on a belt conveyor moving at a constant speed to form a web. The resulting web was then pressed with an embossing roll heated to 80° C. to form a spunbonded nonwoven fabric having the basis weight shown in Table 1, thereby obtaining a second nonwoven fabric layer of Example 10.

[0063] [First Nonwoven Fabric Layer and Coffee Drip Filter] <Examples 1-10, Comparative Examples 1-4> Using polypropylene (MFR 600, PP) with a crystalline melting point of 160°C, a fiber web with an average fiber diameter (diameter) of 3.6 μm was extruded from a melt-blown nozzle at a spinning temperature of 240°C and heated air temperature of 280°C to obtain a first nonwoven fabric layer having the basis weight, thickness, and density shown in Tables 1 and 2, and then laminated on a second nonwoven fabric layer. The laminated first and second nonwoven fabric layers were then cut to the desired size to obtain coffee drip filters for Examples 1-10 and Comparative Examples 1-4. The 45° inclined flow lengths (cm) of the first and second nonwoven fabric layers were also measured for the laminates using the same measurement method as described above. The results are shown in Tables 1 and 2. In Tables 1 and 2, when the 45° inclined flow length is 20.0 cm or more, it is clear that all samples have sufficient hydrophobicity, so all samples are expressed as "20.0 cm."

[0064] Comparative Examples 5 and 6: Using polyethylene terephthalate (with a polymerization ratio of terephthalic acid / isophthalic acid as acid components of 86 / 14), a fiber web with an average fiber diameter of 3.0 μm was extruded from a melt-blown nozzle at a spinning temperature of 320°C and heated air temperature of 370°C, and layered on a second nonwoven fabric layer. Otherwise, coffee drip filters of Comparative Examples 5 and 6 were obtained in the same manner as the coffee drip filters of Examples 1 to 10 and Comparative Examples 1 to 4, and the 45° inclined flow length (cm) was measured. The results are shown in Tables 1 and 2.

[0065] [Coffee Drip Bag] A cup fastener was attached to each coffee drip filter of Examples 1 to 10 and Comparative Examples 1 to 6, and a bag body (external dimensions: 74 mm x 80 mm, seal width: 2 mm) was prepared. Then, 7 g of commercially available ground coffee was sealed (filled) into the bag body to produce the coffee drip bags of Examples 1 to 10 and Comparative Examples 1 to 6. These coffee drip bags were stored in an environment of 50°C and 40% RH. The following evaluation tests were performed on the coffee drip bags immediately after manufacture (after 0 days, i.e., immediately after filling, or in other words, before storage) and after 7 days of storage (after 7 days). The storage temperature of the drip bags was set at a relatively high temperature of 50°C to promote adhesion of oils from the ground coffee to the first nonwoven fabric layer and to perform accelerated testing.

[0066] [Evaluation Test] The coffee drip bag was attached to the top of a cup, and 170 mL of hot water was poured onto the coffee powder. The steaming time X immediately after filling (before storage), the extraction time Y before storage, the steaming time X' after storage, and the extraction time Y' after storage were measured as follows. The relationship between the steaming time and the extraction time was evaluated using the following criteria, and the deterioration of the coffee taste and aroma was predicted based on the evaluation. The results are shown in Tables 1 and 2. (Measurement) Steeping time X (seconds): Before storage, the time required from pouring hot water until the first drop drips into the cup (steeping time before storage). Extraction time Y (seconds): Before storage, the time required from pouring the first drop until 140 mL of extract drips into the cup (extraction time before storage). Steeping time X' (seconds): After storage, the time required from pouring hot water until the first drop drips into the cup (steeping time after storage). Extraction time Y' (seconds): After storage, the time required from pouring the first drop until 140 mL of extract drips into the cup (extraction time after storage). (Evaluation criteria) A: The steaming times X and X' before and after storage are both 2.0 seconds or more, the ratio of the difference in extraction time (Y-Y') between before and after storage and the extraction time Y before storage ({(Y-Y') / Y} x 100) is 40% or less, and the extraction times Y and Y' before and after storage are both 90 seconds or less (excellent). B: The steaming times X and X' before and after storage are both 2.0 seconds or more, the ratio of the difference in extraction time (Y-Y') between before and after storage and the extraction time Y before storage ({(Y-Y') / Y} x 100) is 40% or less, and at least one of the extraction times Y and Y' before and after storage is more than 90 seconds (good). C: At least one of the steaming times X and X' before and after storage is less than 2.0 seconds, or the ratio of the difference in extraction time (Y-Y') between before and after storage and the extraction time Y before storage ({(Y-Y') / Y} x 100) is more than 40% (poor).

[0067]

[0068]

[0069] The first nonwoven fabric layer has hydrophobic properties, the second nonwoven fabric layer does not have hydrophobic properties, and the apparent density of the first nonwoven fabric layer is 0.20 g / cm ３ or more, basis weight is 5 to 15 g / m ２In Examples 1 to 10, which satisfied the above criteria, the steaming times X and X' before and after storage were both 2.0 seconds or more, and the ratio of the difference in extraction time before and after storage to the extraction time before storage ({(Y-Y') / Y} x 100) was 40% or less, indicating that excellent or good results were obtained. In particular, in Examples 1 to 8 and 10, the extraction times Y and Y' before and after storage were both 90 seconds or less, indicating that even better results were obtained. Furthermore, in Examples 2 to 6 and 10, the ratio of the difference in extraction time before and after storage to the extraction time before storage ({(Y-Y') / Y} x 100) was 30% or less, indicating that even better results were obtained. Therefore, it is presumed that the coffee drip bag (coffee drip filter) of the present invention can suppress changes in the taste of coffee obtained by extraction between immediately after filling with coffee powder and after storage while filled.

[0070] In contrast, the apparent density of the first nonwoven fabric layer is 0.20 g / cm ３ In Comparative Examples 1 and 2, where the basis weight of the first nonwoven fabric layer was less than 5 g / m, the ratio of the difference in extraction time before and after storage to the extraction time Y before storage ({(Y-Y') / Y} x 100) exceeded 40%. ２ Comparative Example 3, in which the apparent density is less than 0.20 g / cm ３ In Comparative Example 4, in which the steaming time X was less than 2.0 seconds, at least one of the steaming times X and X' before and after storage was less than 2.0 seconds. In Comparative Examples 5 and 6, in which PET, which is not a hydrophobic resin, was used as the fiber for the first nonwoven fabric layer, the steaming times X and X' before and after storage were both less than 2.0 seconds. Therefore, Comparative Examples 1 to 6 are inferior to Examples 1 to 10, and it is presumed that they are unable to suppress the change in the taste of the coffee obtained by extraction between immediately after filling with coffee powder and after storage with the coffee powder filled.

[0071] The coffee drip filter and coffee drip bag of the present invention can be used to brew various types of coffee, but can also be used to brew tea, broth, soup, medicinal herbs, etc.

[0072] REFERENCE SIGNS LIST 1 Coffee drip filter 3 First nonwoven fabric layer 5 Second nonwoven fabric layer 10 Coffee drip bag 11 Bag body 13 Cup latch 15 Coffee powder 17 Cup

Claims

1. A coffee drip filter comprising a first nonwoven fabric layer that is hydrophobic and comes into contact with coffee grounds, and a second nonwoven fabric layer that is not hydrophobic, wherein the first nonwoven fabric layer has an apparent density of 0.20 g / cm ３ or more, and the basis weight is 5 to 15 g / m ２ This is a coffee drip filter.

2. The coffee drip filter according to claim 1, wherein the first nonwoven fabric layer has a thickness of 75 μm or less.

3. The coffee drip filter according to claim 1, wherein the material constituting the first nonwoven fabric layer is a polyolefin resin.

4. The coffee drip filter according to claim 1, wherein the first nonwoven fabric layer is a melt-blown nonwoven fabric layer.

5. The coffee drip filter according to claim 1, wherein the material constituting the second nonwoven fabric layer is a resin containing polyester.

6. The coffee drip filter according to claim 1, wherein the second nonwoven fabric layer is made of short fibers.

7. The coffee drip filter according to claim 1, wherein the second nonwoven fabric layer is a wet-laid nonwoven fabric layer.

8. A coffee drip filter as described in claim 4, wherein the melt-blown nonwoven fabric layer is an aggregate of fibers formed by melting a hydrophobic resin into fibers by the melt-blowing method and laminating the fibers directly onto the second nonwoven fabric layer.

9. A coffee drip bag formed by manufacturing the coffee drip filter according to any one of claims 1 to 8, comprising: a bag body formed into a bag shape with the first nonwoven fabric layer positioned on the inside; a cup latch attached to the bag body; and coffee powder filled into the bag body.

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