Metal mesh coffee filter and method of forming ceramic layer on filter body of metal mesh coffee filter

Abstract

To provide a metal mesh coffee filter and a method of forming a ceramic layer on a filter body of the metal mesh coffee filter that are related to forming of ceramic coating and solve the problems of clogging with coffee powder, intrusion of fine powder into extracted coffee liquid, and further a reduction in aromatic property of coffee liquid due to coffee oil components being adsorbed onto the filter.SOLUTION: A ceramic layer 2C is formed on surfaces of vertical line 21 and horizontal lines 22 forming a filter body 2. The ceramic layer 2C is made by first applying a coating 2P that forms a hydrophilic coating to front and back surfaces of the filter body 2 to form a hydrophilic film 2H on the vertical lines 21 and the horizontal lines 22, and then re-coating the hydrophilic film 2H with the coating 2P to spread the coating 2P over an entire area of the vertical lines 21 and the horizontal lines 22 through the hydrophilic film 2H.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a coffee filter for brewing coffee, and more particularly to a metal mesh coffee filter that prevents the leakage of fine coffee powder while preventing clogging caused by the fine coffee powder. [Background technology]

[0002] Paper filters are generally used when brewing coffee. They are popular because they are easy to use, but they also have problems with the paper transferring its distinctive smell to the coffee and absorbing the useful oils in the coffee, reducing the flavor and aroma of the extracted coffee. For this reason, users who are particular about the taste and aroma of their coffee use metal mesh filters, such as stainless steel mesh.

[0003] However, metal mesh filters are naturally prone to leaking out fine coffee powder due to the size of the mesh openings, and the fine powder that does not leak out can become clogged at the intersections of the wires that make up the mesh.If this clog grows, it can reduce the filtering function.

[0004] For this reason, the present inventor has already proposed Patent No. 6553546, "Metal Mesh Coffee Filter and Manufacturing Method Thereof" (Patent Document 1) and Patent Publication No. 2021-040964, "Filter for Extracting Extract and Manufacturing Method Thereof" (Patent Document 2), which disclose methods for solving the above problems by using innovative mesh shapes and ceramic coatings, and have been well received by users. However, even with these improvements, when using coffee powder, a naturally derived material, problems such as clogging due to the coffee powder, problems with fine powder being mixed into the extracted coffee liquid, and further problems such as a decrease in the aroma of the coffee liquid due to coffee oil components being adsorbed onto the filter cannot be completely eliminated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6553546 [Patent Document 2] JP 2021-040964 A Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, the present inventors have attempted to clarify the formation of ceramic coatings and have set out to develop a metal mesh coffee filter and a method for forming a ceramic layer on the filter body of a metal mesh coffee filter, which can solve the above problems. [Means for solving the problem]

[0007] First, the metal mesh coffee filter described in claim 1 is a coffee filter comprising a filter body formed of a metal mesh in the shape of a container tapering at the bottom, a coffee powder storage section formed inside the filter body into which appropriate coffee powder is placed to extract coffee liquid, and a ceramic layer is formed on the surfaces of the vertical and horizontal lines forming the filter body, and this ceramic layer is formed by first applying a paint that forms a hydrophilic coating film to the front and back of the filter body to form a hydrophilic film on the vertical and horizontal lines, and then applying paint to the hydrophilic film so that the paint spreads over the entire area of ​​the vertical and horizontal lines through the hydrophilic film.

[0008] The metal mesh coffee filter described in claim 2 has the following features in addition to the requirements of claim 1: the intersections and overlaps of the wires constituting the filter body are smoothed with a ceramic layer.

[0009] The metal mesh coffee filter according to claim 3 is characterized in that, in addition to the requirements of claim 1 or 2, the ceramic layer has pores having a diameter of 0.1 to 3 μm.

[0010] The metal mesh coffee filter described in claim 4 is characterized in that, in addition to the requirements of claim 1 or 2, the paint bonds to the material of the coating surface through ionic bonds.

[0011] The metal mesh coffee filter described in claim 5, in addition to the requirements of claim 1 or 2, is characterized in that the metal mesh is formed in a twill fold, a ceramic layer is formed on its surface, and the filter surface is inclined at an inclination angle so that the passing particle size is set to be smaller than the diameter of fine coffee powder.

[0012] The metal mesh coffee filter described in claim 6 is characterized in that, in addition to the requirements of claim 1 or 2, the thickness of the ceramic layer is 4 to 8% of the diameter of the wire that performs the filtering function.

[0013] The method for forming a ceramic layer on the filter body of a metal mesh coffee filter described in claim 7 is a method for forming a ceramic layer on the filter body of a coffee filter, which comprises a filter body formed in the shape of a container tapered at the bottom using a metal mesh, and a coffee powder storage portion formed inside the filter body into which appropriate coffee powder is placed to extract coffee liquid, and is characterized in that a paint for forming a coating film having hydrophilic properties is first applied to the vertical and horizontal lines that form the filter body to form a hydrophilic film on the vertical and horizontal lines, and then paint is applied over the hydrophilic film, thereby allowing the paint to spread throughout the entire area of ​​the vertical and horizontal lines through the hydrophilic film.

[0014] The method for forming a ceramic layer on the filter body of a metal mesh coffee filter according to claim 8 is characterized in that, in addition to the requirements of claim 7, the intersections and overlapping parts of the wires constituting the filter body are smoothed by the ceramic layer.

[0015] The method for forming a ceramic layer on a filter body in a metal mesh coffee filter according to claim 9 is characterized in that, in addition to the requirements of claim 7 or 8, the ceramic layer has pores having a diameter of 0.1 to 3 μm.

[0016] The method for forming a ceramic layer on the filter body of a metal mesh coffee filter described in claim 10 is characterized in that, in addition to the requirements of claim 7 or 8, the paint is bonded to the material of the coating surface by ionic bonds.

[0017] The method for forming a ceramic layer on the filter body of a metal mesh coffee filter according to claim 11, in addition to the requirements of claim 7 or 8, is characterized in that the metal mesh is formed in a twill fold, and the permeable particle size when the ceramic layer is formed on the surface of the metal mesh and when the filter surface is tilted at an inclination angle set thereon is set to a size smaller than the diameter of fine coffee powder.

[0018] The method for forming a ceramic layer on the filter body of a metal mesh coffee filter according to claim 12 is characterized in that, in addition to the requirements of claim 7 or 8, the thickness of the ceramic layer is 4 to 8% of the diameter of the wire material responsible for the filtering function. The above problems are solved by the configurations of the inventions described in each of these claims. Effect of the Invention

[0019] First, according to the invention described in claims 1 and 7, due to the hydrophilicity of the hydrophilic film formed on the vertical and horizontal lines, paint applied over the hydrophilic film instantly penetrates and spreads over the entire area of ​​the hydrophilic film, increasing the layer thickness. Furthermore, in areas where the paint is applied unevenly or there are areas left unpainted, the overpainted paint expands the hydrophilic film to eliminate these issues, and as a result, a ceramic layer can be formed in which the paint spreads over the entire area of ​​the vertical and horizontal lines. Furthermore, since the entire vertical and horizontal wires are embedded in the ceramic layer and are not exposed, it is possible to prevent coffee powder from getting caught in the wires.

[0020] According to the invention described in claims 2 and 8, the wire can be securely embedded in the ceramic layer, particularly at the intersections and overlaps where coffee powder is likely to get caught. This makes it possible to more reliably prevent the wire from getting caught by coffee powder.

[0021] Furthermore, according to the invention as set forth in claims 3 and 9, fine coffee powder is not trapped in the pores, so that the ceramic layer can be kept clean.

[0022] According to the invention as set forth in claims 4 and 10, the ceramic layer can be made to have excellent strength and can be formed extremely thin.

[0023] According to the invention as set forth in claims 5 and 11, it is possible to obtain the effect of the ceramic layer without impairing the high filtering accuracy of the twill weave wire mesh.

[0024] Furthermore, according to the sixth and twelfth aspects of the invention, it is possible to prevent a decrease in the filtering function due to the formation of the ceramic layer. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1A is a perspective view showing an example of use of the filter of the present invention (metal mesh coffee filter), and FIG. 1B is a perspective view showing the filter in an exploded state except for an upper support material. [Diagram 2] 1A to 1C are a front cross-sectional view, a plan view, and a bottom view of a filter viewed from three directions. [Diagram 3] FIG. 2 is a front cross-sectional view and a left side view of the filter, and is an explanatory view showing an enlarged bottom portion in the front cross-sectional view. [Figure 4] FIG. 1A is an explanatory diagram showing the planar development shape of the flat mesh, which is the initial shape of the filter body, and how it is folded to form a three-dimensional filter body that tapers downward; and FIG. 1B is a projection diagram showing the joint of the flat mesh as viewed from the arrow A in the partial view. [Diagram 5] 1A to 1C are explanatory diagrams showing, in stages, how a flat mesh having a clamping margin is formed into a three-dimensional filter body that tapers downward. [Figure 6] 1A to 1C are front and vertical sectional views showing step-by-step formation of a ceramic layer on a filter body of a metal mesh coffee filter according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention is embodied in the following examples, and includes various other forms and techniques that can be improved within the scope of the technical concept thereof. In the following description, the metal mesh coffee filter 1 will be explained first, and then the manufacturing method of this filter will be explained. EXAMPLES

[0027] The metal mesh coffee filter 1 for extracting essence of the present invention (hereinafter, sometimes simply referred to as filter 1) comprises a filter body 2 formed into a container shape tapered at the bottom by a metal mesh, and after an extract raw material P such as coffee powder is placed inside, hot water is poured from above to extract the extract of the extract raw material P (for example, coffee oil, coffee aroma, etc.). For this reason, the filter 1 of the present invention is mainly suitable for extracting coffee liquid, but it can also be applied to extraction in which, for example, dried bonito flakes, kelp, shiitake mushrooms, etc. are used as the extract raw material P and hot water is poured over the extract raw material P to simply extract the umami components (extract components) of the extract raw material P (so-called broth). Incidentally, broth is originally made by boiling raw materials such as dried bonito flakes, but in this specification, a simple way of making broth, that is, pouring hot water over dried bonito flakes, etc., as the extract raw material P, is also included in the extraction. However, the following explanation is mainly based on the premise of coffee extraction, and in this case, the extraction raw material P is coffee powder ground to an appropriate grain size, such as finely ground, medium ground, or coarse ground.

[0028] The filter 1 of the present invention mainly comprises the filter body 2 formed of a metal mesh into a container shape tapering downward as described above. As shown in Figs. 1 to 3 as an example, this filter body 2 is formed in a sloping shape that is open at the top and tapers downward like a typical paper filter available on the market, and this sloping surface mainly constitutes the filter surface (filtration surface). Naturally, during extraction, an appropriate amount of appropriate extraction raw material P such as coffee powder is put into the inner space of this filter body 2, and this space is referred to as the raw material storage section R.

[0029] The filter body 2 is formed from a metal mesh (SUS) as described above, and in this embodiment, a twill weave wire mesh is used as an example of the metal mesh. This twill folded wire mesh is a plain twill weave with a twill pattern added, and the horizontal lines 22 are woven across every two vertical lines 21, resulting in a double layer of horizontal lines and a structure in which both the front and back sides are in close contact. The twill folded wire mesh is woven in a way that has no openings at all, and a meandering flow path is formed in the depth direction of the wire mesh. An example of the specifications of the twill folded wire netting is shown below. Vertical wire diameter 50 μm, vertical mesh 165, horizontal wire diameter 50 μm, horizontal mesh 600 (the mesh of twill weave wire cloth is expressed by the number of horizontal lines between 25.4 mm (1 inch) openings), mesh size 100 μm, passing particle size 15 μm or less. In this embodiment, the vertical wires 21 and the horizontal wires 22 have the same diameter, but the vertical wires 21 may have a larger diameter than the horizontal wires 22. In this embodiment, a twill weave wire mesh is used as an example of the metal mesh, but various wire meshes woven in other ways, such as a plain weave wire mesh, can also be used.

[0030] As shown in the front cross-sectional view of Figure 2, the filter body 2 constructed using such a twill folded wire mesh has an inclination angle of about 55° on the filter surface, and the transmitted particle size in this inclined state with a ceramic layer 2C formed on the surface as described below is set to a size (1 to 9 μm (or less than 9 μm)) smaller than fine coffee powder (for example, about 20 μm).

[0031] Such a setting is made taking into consideration the gap dimension between the horizontal lines 22 (projected distance when viewed from the vertical direction) as well as the thickness of the ceramic layer 2C, and in the filter 1 of the present invention, the horizontal lines 22 are mainly arranged to prevent fine coffee powder from passing through. In other words, the coffee powder is roasted and has a porous structure, and it is thought that the surface of this fine powder is not smooth but has large and small protrusions.Furthermore, since the extracted liquid flows down the inclined surface (55°) of the filter body 2, much of the fine powder gets caught on the horizontal lines 22. On the other hand, the gap dimension between the vertical lines 21 is larger than the size of fine coffee powder (approximately 20 μm), thereby improving the passage of the extracted coffee liquid and preventing the extraction time from becoming too long.

[0032] The above-mentioned mesh (opening) is merely an example, and the mesh in the horizontal direction can be about 500 to 650 mesh, and the mesh in the vertical direction can be about 100 to 250 mesh.

[0033] As shown in FIG. 4(a) as an example, the filter body 2 is formed in a planar development state in the initial state, which is referred to as a flat mesh W0 in this specification. This flat mesh W0 is then folded appropriately to form a three-dimensional filter body 2 tapered downward. The planar development of the flat mesh W0 can be obtained, for example, by punching out a metal mesh sheet (so-called blank punching). Here, as shown in FIG. 4(a) and FIG. 5, the planar development shape of the flat mesh W0 is a shape in which two approximately isosceles trapezoids are arranged in succession on the left and right, and these approximately isosceles trapezoids are folded in opposing directions so that the central bottom 2B (the bottom 2B of the filter body 2 when formed in a three-dimensional state) is symmetrical (linear). At this time, the sandwiching margins Wa formed on the abutting sides (joints WJ) of the opposing approximately isosceles trapezoids are joined in an overlapping manner to form the filter body 2 tapered downward. For this reason, the filter body 2 is provided with support members 3 that serve as a reinforcing frame at the joints WJ, bottom 2B, upper opening, etc. when formed into a three-dimensional shape, thereby maintaining the three-dimensional shape of the filter body 2.

[0034] The support material 3 will be described below. As shown in Fig. 1(b) and Fig. 2 as an example, the support material 3 is a support member (reinforcing frame material) that basically holds the filter body 2 at an appropriate width from both the inside (raw material storage section R side) and the outside. In particular, at the joint WJ of the three-dimensional filter body 2, the clamping margins Wa formed here are overlapped with each other, and the joint WJ is held at an appropriate width. In this clamped state, the support material 3 and the metal mesh (overlapped portion) are joined together by, for example, spot welding, and integrated. The support material 3 reliably forms the thin mesh filter body 2 into a three-dimensional state, and maintains the three-dimensional state for many years. Here, in the present invention, the filter body 2 is basically one in which the lower end is formed in a flat shape (including a line segment) in a three-dimensional state as shown in Fig. 1, and this may be referred to as a substantially truncated cone shape (three-dimensional trapezoid type) (see Fig. 4(a)). The filter body 2 may also be one in which the lower end is pointed in a three-dimensional state, and this may be referred to as a cone shape.

[0035] Due to this configuration, as shown in Figure 1 above as an example, the support material 3 comprises an inner support material 31 provided on the inside of the three-dimensionally formed filter body 2, an outer support material 32 provided on the outside of the three-dimensionally formed filter body 2, and an upper support material 33 provided at the upper opening (upper open portion) of the three-dimensionally formed filter body 2. Each member constituting the support material 3 will be described below.

[0036] First, as shown in Fig. 1(b) above as an example, the inner support material 31 is formed in a substantially U-shape with the open part of the U-shape facing upward or a substantially V-shape with a flat bottom, and is continuously bent from one joint side (joint part WJ) of the filter body 2 through the bottom part 2B to the other joint side (joint part WJ). That is, the inner support material 31 is bent so as to continuously connect the bottom part 2B of the filter body 2, which is tapered downward in the three-dimensional state, to two opposing lines (two joint lines (joint parts WJ)) on the side peripheral surface located on the extension lines of the bottom part 2B, and serves to firmly support (hold) the filter body 2, particularly the joint part WJ. For this reason, the inner support material 31 comprises a bottom inner support material 31B that supports the bottom 2B of the filter body 2, and a side inner support material 31S that supports the joint WJ (side) of the filter body 2, and is formed so that the elongated side inner support material 31S is bent at an angle relative to the bottom inner support material 31B that is elongated and flat overall. Note that while the bottom inner support material 31B is formed in a substantially flat shape that is not curved in the width direction, it is preferable that the side inner support material 31S is formed so as to be slightly curved in the width direction (short direction), because it is desirable for it to substantially follow the side circumferential surface (curved surface) of the filter body 2.

[0037] In addition, the bottom inner support material 31B has a filtration promotion opening 34, and a metal mesh constituting the filter body 2 is stretched over this filtration promotion opening 34. As a result, the bottom inner support material 31B, which supports and reinforces the bottom 2B of the filter body 2, is also configured to have a filtering function. In this way, the filtration promotion opening 34 is formed in the bottom inner support material 31B, which improves and promotes the filtering action, prevents over-extraction of the extract, which occurs when the filter bottom is formed to be blocked, and prevents impurities from being mixed into the extract (coffee liquid). For this reason, in this specification, the opening formed in the bottom 2B (bottom inner support material 31B) of the filter body 2 is referred to as the filtration promotion opening 34.

[0038] In addition, since the filter body 2 is stretched over the bottom 2B (bottom inner support material 31B), it is preferable that the filtration promotion opening 34 is opened to a size as large as possible. That is, since the idea is that fine powder of the coffee powder (extraction raw material P) is captured by the filter body 2 in the bottom 2B, the filtration promotion opening 34 itself can be opened to a large size without considering whether the fine powder passes or does not pass. In other words, from the viewpoint of improving the passability of the extract (coffee liquid), it is preferable that the filtration promotion opening 34 is opened to a size as large as possible within a range that does not impair the strength of the bottom inner support material 31B. At least in the case of coffee extraction, the filtration promotion opening 34 is formed to a size larger than the grain size of coarsely ground coffee powder (for example, grain size of about 0.72 to 0.92 mm). During extraction, as shown in the partially enlarged view of FIG. 3 as an example, the extraction raw materials P (fine coffee powder and coffee grounds) captured by the filter body 2 are accumulated in the filtration promotion opening 34. However, by opening the filtration promotion opening 34 to a large size, the captured and accumulated extraction raw materials P (coffee grounds) do not clog the filtration promotion opening 34 (no bridges are formed), and after extraction, the extraction raw materials P (coffee grounds) can be easily removed from the filtration promotion opening 34 by simply rinsing with water from both the inside and outside sides.

[0039] Here, the size of the filtration promotion opening 34 will be specifically explained. When the width dimension of the bottom inner support material 31B is approximately 8 mm and the length dimension is approximately 39 mm, the filtration promotion opening 34 is formed as an elliptical opening, for example, as shown in Figures 1 and 2, and its size, for example, is approximately 6 mm in the short axis direction and approximately 35 mm in the long axis direction.

[0040] Next, the outer support member 32 will be described. The outer support material 32 is a member that is paired with the above-mentioned inner support material 31 (particularly the side inner support material 31S) and is provided so as to sandwich the filter body 2. In other words, the outer support material 32 serves to support the filter body 2 from the outside (outside the raw material storage section R). However, in this embodiment, the outer support material 32 is not present near the center of the bottom of the filter body 2 where the filtration promotion opening 34 is formed, in order to allow smooth filtration by the filter body 2 (the filter body 2 stretched over the filtration promotion opening 34). 1(b) above, the outer support material 32 is configured to be substantially divided by a pair of left and right outer side support materials 32S, while the bottom 2B of the filter body 2 is supported by a covering cap 35, which will be described later. Incidentally, the gap below the outer support materials 32 (outer side support materials 32S) that are provided in a divided state on the left and right sides is included in the filtration promotion opening 34 in a broad sense. Furthermore, since the entire filter body 2 (filter surface) is formed in an inclined shape that tapers downward, it is preferable that the outer support material 32 be formed somewhat wider than the inner support material 31 in order to firmly clamp the filter body 2. Further, the outer support member 32 (the outer side support member 32S) is formed in substantially the same inclined state as the inner side support member 31S.

[0041] Next, the covering cap 35 that supports the bottom portion 2B of the filter body 2 will be described. As shown in FIG. 1(b) as an example, the covering cap 35 is attached by welding or the like so as to support the bottom 2B of the filter body 2, more specifically, both end corners of the bottom 2B, from below. The covering cap 35 is attached by butting its upper end against the lower end of the outer support member 32, as shown in the enlarged view of FIG. As shown in FIG. 1(b) above, the covering cap 35 has upright wall portions 35W formed on both sides, and is attached so as to fit (cover) the bottom 2B (four corners) of the filter body 2 inside these upright wall portions 35W. The filter body 2 is formed by bending the left and right approximately isosceles trapezoid formed from a metal mesh from both sides at the bottom 2B of the filter body 2. During this bending, pinholes could occur at the four corners at both ends of the bottom 2B. However, even if pinholes do occur, they are reliably covered by the covering cap 35, resulting in a structure that barely allows coffee powder to pass through the pinholes (prevents them from mixing with the coffee liquid that is the extracted liquid).

[0042] Next, the upper support member 33 will be described. The upper support member 33 is a frame member (reinforcement frame member) for supporting the upper opening (upper open portion) of the filter body 2 formed into a three-dimensional shape as described above, and this upper support member 33 is also provided so as to clamp the opening edge of the filter body 2 from the inside and outside all around. The upper support member 33 and the metal mesh (filter body 2) are integrated at this clamped portion by welding (for example, spot welding, etc.). When the upper support member 33 is to be distinguished between the inside and outside, it is referred to as the inner upper support member 33I and the outer upper support member 33U. Incidentally, as shown in the partially enlarged view of Figure 2, the inner upper support material 33I is formed by folding (in a flange shape) so as to protrude from the top surface side toward the outer periphery, and a part of it further protrudes toward the outer periphery in a protruding manner to form a handle 36 of the filter 1. Furthermore, as shown in Figure 2 (particularly the partially enlarged view), it is preferable that the upper support material 33 is arranged so as to abut against the upper ends of the inner support material 31 and the outer support material 32 described above, thereby integrating the support material 3 as a whole and achieving overall shape maintenance and increased strength of the three-dimensionally formed filter body 2.

[0043] In addition, when forming the filter body 2 into a three-dimensional shape from the flat mesh W0, as described above, the approximately isosceles trapezoidal joints WJ are overlapped with each other as shown in Figure 4(b) as an example, and this overlapping portion is called the clamping allowance Wa. In addition, here, before being supported by the support material 3, the clamping margin Wa of the flat mesh W0, which is a metal mesh, is first overlapped and spot welded, thereby making it easier to subsequently clamp and join the inner support material 31 and the outer support material 32. Incidentally, the planar development shape of the flat mesh W0 is, for example, as shown in Figures 4(a) and 5, formed with a clamping margin Wa, which serves as a fold-in piece, extending in the longitudinal (fold line) direction of the bottom portion 2B, for example, with a length of about 10 mm. In forming the flat mesh W0 into a three-dimensional shape, the clamping margins Wa formed at the approximately isosceles trapezoidal joints WJ are first folded so as to overlap each other, and then the folded-in pieces (clamping margins Wa) are folded from the outside of the overlapped joints WJ so as to overlap each other (see FIG. 5). As a result, the extensions at both ends of the bottom 2B are formed by a total of three clamping margins Wa (mesh fabric) overlapping each other (see "triple" in FIGS. 4 and 5), and the other joints WJ are formed by a total of two clamping margins Wa (mesh fabric) overlapping each other. Of course, by overlapping three or two clamping margins Wa in this way, the thickness dimension increases accordingly, but since it is sandwiched between the inner support material 31 and the outer support material 32, which are about 1 mm thick, there is no adverse effect. Furthermore, as will be described in more detail later, after the flat mesh W0 is formed into a three-dimensional shape to form the filter body 2, a ceramic baking coating is applied to the entire front and back surfaces of the filter, so that tiny gaps can be filled by the flow of this coating material.

[0044] As an example, filter 1 is configured by providing a cup mounting stand 4 on the lower part of filter body 2, as shown by imaginary lines (double-dashed lines) in Figures 1(a) and 3, so that filter body 2 can be held above cup C. The cup mounting base 4 comprises a hollow disk 41 to be placed on the opening edge of a cup C (including a server, etc.) for storing an extracted liquid such as coffee liquid, and has a downwardly tapered folded-back portion 42 formed continuously in the approximate center. This folded-back portion 42 is fixed to the outer support member 32 of the filter body 2 by welding or the like, and is integrated with the filter body 2 (integration of the filter body 2 and the cup mounting base 4). For this reason, the downward tapering angle (inclined angle) of the folded-back portion 42 is approximately the same as that of the outer support member 32. Incidentally, although the cup mounting stand 4 has been described here as being fixed to the filter body 2, the cup mounting stand 4 may also be provided detachably from the filter body 2.

[0045] As a characteristic feature of the present invention, the front and back surfaces of the filter body 2 are coated with a ceramic material to form a ceramic layer 2C. The formation of such a ceramic layer 2C is a coating treatment that enhances hydrophilicity; after the coffee liquid has been extracted, first rinse off the coffee grounds adhering to the filter body 2 with running water, and then simply scrub the filter body 2 lightly with a sponge or the like; or, after soaking the filter body 2 in water, scrub the filter body 2 lightly with a sponge or the like under running water; the water will penetrate between the coating of the ceramic layer 2C and the dirt, causing the dirt to float up and be easily removed.

[0046] As the paint 2P used to form the ceramic layer 2C, for example, Verascoat manufactured by Shinkosha Co., Ltd. is adopted. This paint bonds to the material of the coating surface (SUS) through ionic bonds, and exhibits a much stronger bond than general paints, which bond to the material of the coating surface through van der Waals forces. Incidentally, using a coating that matches the expansion coefficient of the metal being coated reduces the occurrence of peeling and cracking. In addition, in this embodiment, since the thickness of the ceramic layer 2C is 2 to 4 μm as described below, the particle size of silica, which is the main component of the paint 2P, is optimized by milling the paint 2P to adjust the particle size to 300 to 500 nm (7.5 to 25% of the thickness of the ceramic layer 2C).

[0047] Furthermore, in the ceramic layer 2C formed by the coating material 2P, numerous pores are formed, and the diameter of these pores is set to 0.1 to 3 μm. By setting the diameter of the pores as described above, clogging of the pores with fine coffee powder (20 μm) can be prevented. As for coffee oil, the surface tension of the oil prevents it from penetrating into the pores, and since the ceramic layer 2C is hydrophilic, the coffee oil components are repelled by the ceramic layer 2C and pass through the filter body 2 together with the coffee extract.

[0048] Although such a ceramic layer 2C is disclosed in the prior art already mentioned, the present invention is based on the discovery of an almost optimal mode for its formation as a result of much trial and error. That is, the ceramic layer 2C is required to be formed with a suitable thickness in order to fully exert its hydrophilicity. However, such a measure essentially narrows the mesh interval (opening), and therefore it is not necessarily easy to find the optimum thickness of the ceramic layer 2C. In addition, coffee powder is a natural material, and depending on how the coffee beans are ground, they can be coarsely ground, medium ground, or fine ground. Even if there is an average particle size, these particle sizes are not uniform, and the production of finely ground coffee powder is inevitable. Taking these conditions into consideration, the present invention has clarified the optimum thickness of the ceramic layer 2C, and ultimately determined that the thickness dimension of the ceramic layer 2C to be formed is 2 to 4 μm (4 to 8% of the diameter of the horizontal wires 22 that perform the filtering function). The reason why the ceramic layer 2C can be made into such an extremely thin film is that the paint 2P is strongly bonded to the material (SUS) of the coating surface by ionic bonds, as described above.

[0049] Furthermore, according to the present invention, the ceramic layer 2C set to such a thickness dimension can be formed on the surfaces of the wire portions (vertical lines 21, horizontal lines 22) of the filter body 2, as will be described in detail later, and can also be reliably formed in areas where it is desirable to reliably form the ceramic layer 2C, such as the intersections 2X and overlapping portions 2W of the wire portions, i.e., areas where fine coffee powder may become clogged (trapped). The intersection 2X of the wires is the area where the vertical line 21 and the horizontal line 22 intersect, while the overlapping area 2W is the area where adjacent wires come into contact with each other, both of which are areas where fine coffee powder may become trapped. The overlapping portion 2W includes not only the overlapping between the wire rods but also the portion where the wire rods and the support material 3 overlap.

[0050] Incidentally, in the conventional method of forming the ceramic layer 2C with such a thickness dimension, the paint 2P does not spread well over the entire area of ​​the thin wire due to surface tension, and the paint 2P is not sufficiently applied to the intersections 2X of the wires, overlaps 2W, etc. If the paint 2P is applied again to the remaining areas, the ceramic layer 2C becomes thicker, and as a result, it is unavoidable that the mesh size becomes smaller. On the other hand, according to the present invention, the coating material 2P is not left uncoated and the desired mesh size can be ensured.

[0051] The metal mesh coffee filter 1 of the present invention has the basic structure as described above, and a method for producing such a filter 1 will be described below. (1) Planar development shape of flat mesh The filter body 2 is three-dimensionally formed from the flat mesh W0 that is in a planar development state in the initial state as described above, and as an example of its planar development shape, as shown in Fig. 4(a), two approximately isosceles trapezoids are arranged symmetrically with the lower end (bottom 2B when formed three-dimensionally) of the filter body 2. When forming the filter body three-dimensionally, the two approximately isosceles trapezoids are folded at the symmetrical bottom 2B, and the two approximately isosceles trapezoids are formed three-dimensionally by joining the sides of the two approximately isosceles trapezoids (here, the joined sides of the approximately isosceles trapezoids are the joint WJ). To explain the shape of the flat mesh W0 in more detail, first, the joints WJ are provided with clamping margins Wa for overlapping each other. A clamping margin Wa is also provided on the extension of the length (fold line) of the bottom portion 2B when it is formed into a three-dimensional shape, and this is a folded piece provided to protrude from the end portion of the bottom portion 2B by, for example, about 10 mm. Here, the symbol "WB" in the figure indicates a bottom fold line for folding two approximately isosceles trapezoids with respect to the bottom 2B, and here, two are formed in parallel. Also, the symbol "WS" in the figure indicates a side fold line for folding the clamping margin Wa formed at the joint WJ.

[0052] In order to obtain the flat mesh W0 having such a shape, as described above, for example, the flat mesh W0 having the above shape can be punched out from a long mesh sheet (blank punching). Furthermore, by shortening the longitudinal dimension of bottom portion 2B in FIG. 4(a), it is possible to obtain a filter 1 that is approximately conical in shape rather than approximately truncated cone in shape (three-dimensional trapezoidal type) as a three-dimensional filter body 2, which is intended to be compatible with a conventional cone-shaped dripper.

[0053] (2) Folding the flat mesh Then, the flat mesh W0 as described above is formed into a three-dimensional filter body 2 tapered downward, and for this, as shown in Figures 4(a) and 5, first, the clamping tabs Wa formed at the approximately isosceles trapezoidal joint WJ are folded so as to overlap. Next, the clamping tabs Wa formed as folded pieces extending from both ends of the bottom portion 2B are folded so as to overlap further outward from the overlapped joint WJ. As a result, the extensions at both ends of the bottom portion 2B are formed by a total of three clamping tabs Wa (mesh fabric) overlapping each other, and the other joints WJ are formed by a total of two clamping tabs Wa (mesh fabric) overlapping each other. In this embodiment, the extensions at both ends of the bottom 2B are folded over so that the clamping margins Wa formed at the extensions are positioned at the outermost positions of the filter body 2. The mesh fabric (metal mesh) forming the clamping margins Wa is thin, but has a thickness, so that the clamping margins Wa may not be precisely overlapped at the extensions at both ends of the bottom, which are three-ply laminated, and may protrude somewhat from the corners. However, in this embodiment, the covering caps 35 are fitted from the lower outside to both ends of the bottom 2B, so that even if the clamping margins Wa protrude from the corners, they are contained within (covered by) the standing wall portions 35W of the covering caps 35, and are prevented from being exposed to the outside.

[0054] (3) Spot welding (temporary welding) Thereafter, with the clamping margins Wa overlapped as described above, the clamping margins Wa of the flat mesh W0 are spot welded (temporarily welded) prior to clamping by the support material 3. By performing spot welding prior to clamping by the support material 3, it becomes easier to perform the subsequent clamping and joining by the support material 3. In performing spot welding, for example, two opposing sides of an approximately isosceles trapezoid in a flat mesh W0 (the clamping allowance Wa of the joint WJ) are overlapped on top of an appropriate receiving jig, and then this overlapped portion (clamping allowance Wa) is spot welded.

[0055] (4) Clamping between inner and outer supporting materials Thereafter, the flat mesh W0 (filter body 2) is sandwiched from the inside and outside by the support material 3 (the inner support material 31 and the outer support material 32), and in this sandwiched state, the support material 3 and the filter body 2 (metal mesh) are joined by welding (for example, spot welding) or the like (see the enlarged view of FIG. 4(a)). Of course, after the outer support material 32 is attached, the covering cap 35 is joined so as to abut against its lower end. The spacing between the spot welds when joining the support material 3 and the filter body 2 may be equal above and below the joint WJ (clamping allowance Wa). However, since the filtering action of the filter surface is mainly on the lower side (approximately the lower half), it is preferable to make the spacing between the welds smaller the further downwards. Furthermore, among the support materials 3, particularly the inner support material 31, the bottom inner support material 31B supporting the bottom 2B and the side inner support materials 31S supporting the joints WJ on both sides thereof are arranged in a straight line when viewed from above, thereby strengthening the filter body 2.

[0056] (5) Installation of upper support The upper opening of the filter body 2 thus formed into a three-dimensional shape is fitted with the upper support member 33 over the entire periphery as described above (see FIG. 2). Specifically, the inner upper support member 33I and the outer upper support member 33U are fitted so as to sandwich the upper opening edge of the filter body 2 from the inside and outside. These upper support members 33 are provided so as to abut against the upper ends of the inner support member 31 and the outer support member 32 as described above (see the partially enlarged view of FIG. 2).

[0057] (6) Formation of ceramic layer Thereafter, a ceramic coating is applied to all of the front and back surfaces of the filter body 2 to form the ceramic layer 2C, and the method for this will be described below.

[0058] i) Undercoat First, as shown in Figures 6(a) and (b), paint 2P is applied (spray applied) to the front and back of the filter body 2 to form a hydrophilic film 2H on the vertical lines 21 and horizontal lines 22 with a film thickness of 0.5 to 1.0 μm. In this embodiment, as an example, a film thickness of 1.0 μm is formed. The thickness dimension of the hydrophilic film 2H is set to a value smaller than the thickness of the ceramic layer 2C, which is 4 to 8% (2 to 4 μm in this embodiment) of the diameter of the wire (horizontal wire 22) that performs the filtering function, thereby making it possible to apply paint 2P multiple times.

[0059] ii) Layering Next, as shown in Fig. 6(c), paint 2P is applied over this hydrophilic film 2H, and the applied paint 2P instantly penetrates and spreads over the entire area of ​​the hydrophilic film 2H, wetting it. Furthermore, in areas where the paint 2P is applied unevenly or there are areas left unpainted, the applied paint 2P expands the hydrophilic film 2H to eliminate these issues, and as a result, the paint 2P spreads over the entire areas of the vertical lines 21 and horizontal lines 22. Such coating of paint 2P can be carried out multiple times until paint 2P spreads over the entire area of ​​vertical line 21 and horizontal line 22, but should be carried out in such a way that the thickness of the formed ceramic layer 2C does not exceed 4 to 8% of the diameter of horizontal line 22 (2 to 4 μm in this embodiment, since the diameter of horizontal line 22 is 50 μm).

[0060] In addition, at the intersection 2X, the paint 2P applied to the vertical line 21 and the paint 2P applied to the horizontal line 22 form an arc-shaped portion 2L by the surface tension acting on each of them, making the inside corner a so-called smoothed state, so that the paint 2P can sufficiently fill the minute gaps that occur at the intersection 2X. Also, the minute gaps that occur at the overlapping portion 2W are filled with the paint 2P. The above-mentioned paint 2P should be applied over and over before the lower layer of paint 2P dries too much.

[0061] iii) Baking After the coating is completed as described above, the filter body 2 coated with the paint 2P is then baked, and the filter body 2 is placed in a heating furnace and heated, for example, at 300°C for about 60 to 90 minutes (the moisture content is first evaporated, the temperature is gradually raised after evaporation, and the temperature is gradually lowered after the ceramics are fixed). The paint 2P thus heat-treated hardens, and the ceramic layer 2C is baked and formed on the filter body 2.

[0062] (7) Attaching the cup holder Next, the cup mounting base 4 is assembled to the filter body 2, and the folded-back portion 42 of the cup mounting base 4 is fixed to the outer support member 32 of the filter body 2 by welding or the like.

[0063] The metal mesh coffee filter 1 of the present invention is manufactured as described above as an example. The filter 1 manufactured in this manner has pores formed in the ceramic layer 2C with a diameter of 0.1 to 3 μm, so that fine coffee powder (about 20 μm) is not trapped in the pores. Even if the filter body 2 becomes dirty, the hydrophilicity of the ceramic layer 2C allows water to penetrate underneath the dirt and float it away, so that the filter body 2 can be easily cleaned with just water, allowing anyone to easily perform daily hygiene maintenance. Furthermore, the surface tension of the oil prevents the coffee oil from penetrating the pores of the ceramic layer 2C, and since the ceramic layer 2C is hydrophilic, the coffee oil is repelled by the ceramic layer 2C and passes through the filter body 2 together with the coffee extract, thereby obtaining a coffee extract that is excellent in the original coffee aroma.

[0064] As described above, the extensions at both ends of the bottom 2B are formed by overlapping three sheets of sandwiching margin Wa (mesh), which increases the thickness of the corresponding parts. However, since the ceramic layer 2C is formed on the entire front and back of the filter body 2 after three-dimensional formation, the tiny gaps are not only filled by the flow of paint 2P, but also smoothed by the formation of the arc-shaped portion 2L according to the specifications disclosed in this invention, and this configuration prevents clogging with fine coffee powder. [Explanation of symbols]

[0065] 1 Metal mesh coffee filter (filter) 2 Filter body 3 Support material 4 Cup Stand 21 Vertical Line 22 Horizontal Line 2B Bottom 2C Ceramic Layer 2H Hydrophilic membrane 2X intersection 2P paint 2L arc section 2W overlapping part 31 Inner support 31B Bottom inner support 31S Side inner support 32 Outer support material 32S Side outer support 33 Upper support material 33I Inner upper support 33U outer upper support 34 Filtration promotion opening 35 Covering cap 35W standing wall 36 Handle 41 Hollow Disk 42 Folded part W0 Flat mesh WJ joint WB Bottom broken line WS Side bend line Wa clamping allowance C Cup P extraction raw material R Raw material storage section

Claims

1. A coffee filter comprising a filter body formed of a metal mesh in the shape of a container tapered at the bottom, and a coffee powder storage section formed inside the filter body for storing appropriate coffee powder and extracting coffee liquid, A ceramic layer is formed on the surfaces of the vertical and horizontal lines forming the filter body, This ceramic layer is coated with a coating material that forms a hydrophilic coating film. First, apply a coating to the front and back of the filter body to form a hydrophilic film along the vertical and horizontal lines, Then, paint is applied to the hydrophilic film so that the paint spreads over the entire area of ​​the vertical and horizontal lines through the hydrophilic film, resulting in a metallic mesh coffee filter.

2. 2. The metal mesh coffee filter according to claim 1, wherein the intersections and overlaps of the wires constituting said filter body are smoothed with a ceramic layer.

3. 3. The metal mesh coffee filter according to claim 1, wherein the ceramic layer has pores having a diameter of 0.1 to 3 μm.

4. 3. The metal mesh coffee filter according to claim 1, wherein the paint is bonded to the material of the surface to which it is applied by ionic bonding.

5. 3. The metal mesh coffee filter according to claim 1, wherein the metal mesh is formed by twill folding, and the ceramic layer is formed on the surface of the metal mesh, and the filter surface is tilted at an inclination angle set so that the passing particle size is smaller than the diameter of fine coffee powder.

6. 3. The metal mesh coffee filter according to claim 1 or 2, wherein the thickness of the ceramic layer is 4 to 8% of the diameter of the wire that performs the filtering function.

7. A method for forming a ceramic layer on a filter body of a coffee filter, which comprises a filter body formed of a metal mesh in a container shape tapered downward, and a coffee powder storage portion formed inside the filter body, which stores appropriate coffee powder and extracts coffee liquid, comprising: The longitudinal and transverse lines forming the filter body are First, a coating material that forms a hydrophilic coating film is applied to form a hydrophilic film on the vertical and horizontal lines; Next, paint is applied to the hydrophilic film so that the paint spreads over the entire area of ​​the vertical and horizontal lines through the hydrophilic film. This method for forming a ceramic layer on the filter body of a metal mesh coffee filter is characterized by the above.

8. 8. The method for forming a ceramic layer on a filter body in a metal mesh coffee filter according to claim 7, characterized in that the intersections and overlaps of the wires constituting the filter body are smoothed by a ceramic layer.

9. 9. The method for forming a ceramic layer on a filter body in a metal mesh coffee filter according to claim 7 or 8, wherein the ceramic layer has pores having a diameter of 0.1 to 3 μm.

10. 9. The method for forming a ceramic layer on a filter body of a metal mesh coffee filter according to claim 7 or 8, wherein the paint is bonded to the material of the coating surface by ionic bonds.

11. 9. A method for forming a ceramic layer on a filter body in a metal mesh coffee filter as claimed in claim 7 or 8, characterized in that the metal mesh is formed by twill folding, and the ceramic layer is formed on its surface, and the filter surface is inclined at an inclination angle set so that the penetration particle size is set to be smaller than the diameter of fine coffee powder.

12. 9. The method for forming a ceramic layer on the filter body of a metal mesh coffee filter according to claim 7 or 8, characterized in that the thickness of the ceramic layer is 4 to 8% of the diameter of the wire material performing the filtering function.

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