Blood filter and blood filter member

Abstract

According to the present invention, it is possible to provide a blood filter capable of removing foreign substances such as thrombus and protein substances while maintaining a sufficient blood filtration flow rate. A blood filtration filter which is a mesh-like blood filtration filter formed from resin fibers, and which is characterized in that the number of meshes is 300 or more, the aperture ratio is 30-50%, the fiber diameter of the fibers is 10-40 [mu] m, and the woven fabric is a plain weave or a three-page twill weave.

Description

Technical Field

[0001] The present invention relates to a blood filtration filter used for a hemodialysis device, an artificial heart and lung, etc. Background Art

[0002] In the hemodialysis device used for blood purification in the artificial heart and lung used in the treatment of respiratory failure caused by COVID-19 infection, pneumonia, etc., and the treatment of renal failure, there is a blood filtration filter for removing thrombi and protein substances generated during the circulation of the patient's blood. Most of the treatments last for a long time. If biological components such as blood and body fluids come into contact with the surface of the materials used in medical equipment, the materials are identified as foreign matter, and sometimes platelets and proteins are attached, the performance of the materials is reduced, and then serious problems such as biological reactions and thrombus formation occur. In this regard, a technology for improving blood compatibility and preventing thrombus formation by coating heparin or hydrophilic polymers on the surface of the blood circuit that is in contact with blood is disclosed (Patent Document 1); a method for imparting anti-thrombotic properties and reducing the amount of anticoagulants used by modifying fluorine-based polymers on the surface of the blood circuit is disclosed (Patent Document 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-8693

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-52525 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] Another reason for the generation of thrombus is the blood filtration flow rate of the blood filtration filter. It is known that if the blood filtration flow rate of the blood filtration filter is small, the blood will be turbulent, and the retained blood will increase, which will become the cause of thrombus. Therefore, in order to increase the blood filtration flow rate of the blood filtration filter, it is considered to increase the opening rate of the filter, but if the opening rate is excessively increased, the thrombus and protein substances to be removed will pass through. Therefore, the object of the present invention is to provide a blood filtration filter that can fully maintain the blood filtration flow rate and can also remove foreign matter such as thrombus and protein substances.

[0009] Solutions for solving problems

[0010] That is, a solution for solving the above-mentioned problem is as follows.

[0011] (1) A blood filtration filter, characterized in that it is a mesh-like blood filtration filter formed of resin fibers, the number of meshes is 300 or more, the opening rate is 30% or more and 50% or less, the fiber diameter of the aforementioned fibers is 10 μm or more and 40 μm or less, and the fabric structure is a plain weave or a three-page twill weave.

[0012] (2) The blood filtration filter according to (1) above, wherein the standard deviation of the opening size in the longitudinal direction and the standard deviation of the opening size in the latitudinal direction of the blood filtration filter are less than 3 μm.

[0013] (3) The blood filtration filter according to (1) above, wherein the blood filtration filter is formed of monofilament fibers.

[0014] (4) The blood filtration filter according to (1) above, wherein an OP (wire pitch) of the blood filtration filter is not less than 20 μm and not more than 50 μm.

[0015] (5) A blood filtration filter member comprising the blood filtration filter according to any one of (1) to (4) above and a supporting member for supporting the blood filtration filter.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a blood filtration filter capable of removing foreign matter such as thrombus and protein substances while maintaining a sufficient blood filtration flow rate. DETAILED DESCRIPTION

[0018] The blood filtration filter of this embodiment is described in detail below. The blood filtration filter of this embodiment is a mesh filter formed by weaving silk (fibers), and functions as a filter that allows blood to pass through the openings of the woven fabric and removes foreign matter such as thrombus.

[0019] It should be noted that the mesh count referred to in this specification refers to the number of weft or warp threads (threads / inch) parallel to the warp or weft threads of the fabric forming the blood filtration filter per 25.4 mm (1 inch) length.

[0020] In addition, the opening ratio is an index indicating the area ratio of the opening part of the mesh fabric, and can be obtained by the following formula (1). In the present embodiment, the opening ratio is a value obtained by measuring the OP and the yarn diameter at 20 points in the warp and weft directions respectively using a digital microscope, etc., and obtaining the respective average values, and substituting the average values ​​into the following formula (1) as the values ​​of the warp OP, weft OP, warp yarn diameter, and weft yarn diameter to obtain the above-mentioned opening ratio. The yarn diameter can be obtained by measuring the yarn diameter of the yarn located outside the position where the OP is measured.

[0021] Opening rate (%) = (warp OP × weft OP) / ((warp OP + weft diameter) × (weft OP + warp diameter)) × 100 (1)

[0022] OP (wire pitch) is the distance between wires, warp OP is the distance between weft wires, and weft OP is the distance between warp wires. In the present embodiment, OP is the value actually measured using a digital microscope. In addition, the wire diameter can also be measured using a digital microscope. Since the wires at the intersections are flattened and become thicker, it is advisable to measure OP and wire diameter at the middle position between the intersections that are not affected by flattening. It should be noted that in the case where the warp and weft wires cannot be distinguished, any one wire is set as the warp wire, and the other is set as the weft wire. In this case, the distance between the weft wires is set as the warp OP, and the distance between the warp wires is set as the weft OP.

[0023] In addition, in this specification, "opening" or "opening part" refers to the space part of the mesh (not including the thread).

[0024] First, the blood filtration filter of the present embodiment is characterized in that the fiber diameter (filament diameter) of the warp and weft yarns constituting the fabric (mesh-like material) is greater than 10 μm and less than 40 μm. In order to increase the blood filtration flow rate, it is preferred to weave a fabric with a higher opening rate, but as mentioned above, foreign matter such as thrombus cannot be removed simply by increasing the opening rate. Therefore, in the present embodiment, in order to remove foreign matter, the OP of the fabric is reduced by making the mesh number higher than 300 meshes, and a blood filtration filter with a high opening rate is developed by using fibers with a small fiber diameter of greater than 10 μm and less than 40 μm. When the fiber diameter is less than 10 μm, the strength of the fiber is insufficient, which becomes a cause of filter rupture, and fibers with a fiber diameter greater than 40 μm are difficult to manufacture the fabric with a high opening rate described later. It should be noted that the warp and weft yarns preferably use fibers with the same fiber diameter.

[0025] In the blood filtration filter of the present embodiment, the mesh count is 300 or more as described above. The mesh count in the warp direction in which the warp yarns extend and in the weft direction in which the weft yarns extend may be the same or different. Even in different cases, the mesh count in any direction is 300 or more. By setting it to 300 or more mesh, if it is a fiber with a fiber diameter of the present embodiment, the OP of the filter can be sufficiently reduced as described above, and foreign matter such as thrombus can be removed. If it is less than 300 mesh, it cannot fully remove foreign matter as a blood filtration filter. It should be noted that the upper limit of the mesh count of the filter of the present embodiment is not particularly limited. According to current weaving technology and the wire diameter of synthetic fibers that can be obtained, 800 mesh is considered to be the limit, so it can be set to less than 800 mesh.

[0026] The OP of the blood filtration filter is preferably greater than 20 μm and less than 50 μm. This is because if it is less than 20 μm, necessary components such as red blood cells may be removed, and if it is greater than 50 μm, foreign matter such as thrombus cannot be removed. It should be noted that the OP can be the same size in the warp and weft directions, or different sizes. The OP is more preferably less than 40 μm. If it is less than 40 μm, foreign matter can be removed more fully.

[0027] The fiber constituting the blood filtration filter of this embodiment can be made of resin. The resin used as the fiber of the blood filtration filter is not particularly limited as long as it can be formed into a fiber shape, and the user can select it appropriately. As the resin, for example, a thermoplastic resin or a thermoplastic elastomer can be used. Specifically, examples include polyethylene resins, polypropylene resins, polystyrene resins, ABS resins, AS resins, EVA resins, polymethylpentene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polymethyl acrylate resins, polyvinyl acetate resins, polyamide resins, polyimide resins, polycarbonate resins, polyester resins such as polyethylene terephthalate resins (PET) and polybutylene terephthalate resins, thermoplastic resins such as polyacetal resins, polyarylate resins, polysulfone resins, polyphenylene sulfide (PPS) and liquid crystal polymers (LCP), silicone resins, styrene elastomers such as polystyrene elastomers, olefin elastomers such as polyethylene elastomers and polypropylene elastomers, polyurethane elastomers such as polyurethane elastomers, vinyl chloride elastomers, polyester elastomers, and thermoplastic elastomers such as nylon elastomers.

[0028] The fiber forming the blood filtration filter of this embodiment may be a monofilament or a multifilament, but in order to obtain a high opening ratio, a monofilament is preferably used because the possibility of the opening ratio being reduced due to fiber flattening or the like is small.

[0029] Next, the blood filtration filter of the present embodiment is a fabric with an opening rate of 30% or more and 50% or less. If the opening rate is less than 30%, the blood that cannot pass through the filter is retained near the filter inlet, and the flow of blood becomes poor. As a result, the contact time between the medical equipment located on the upstream and downstream sides of the blood filtration filter and the blood becomes longer, and thrombus is easily generated. If thrombus is generated, the filter is easily clogged, so the blood filtration flow rate is further reduced, for example, which may cause the patient's health condition to deteriorate. In addition, if the opening rate is higher than 50%, the mesh misalignment becomes larger, the OP becomes inconsistent, or the filter strength is reduced, which becomes a cause of damage, etc., so it is not preferred. From the relationship between the stability of the fabric and the blood filtration flow rate, it is more preferable to set the opening rate to 40% or more and 45% or less.

[0030] Furthermore, the blood filtration filter of the present embodiment is characterized in that its fabric structure is a plain weave or a three-page twill (Weaving 2:1twill). Plain weave refers to a fabric formed by crossing and weaving one warp and one weft. Twill is a fabric also called a twill weave, which is woven by repeatedly passing the warp over 2 or 3 wefts and then under 1 weft. Among twill structures, a structure that crosses the warp in a manner that allows the warp to pass over 2 wefts and under 1 weft is called "three pages", also known as 2 / 1 twill or 2 / 1 twill weave. The 1 / 2 twill structure in which the weaving method of the warp and weft is opposite is also a three-page twill structure of the same fabric structure. In the present embodiment, the three-page twill structure is recorded as a three-page twill structure.

[0031] For the blood filtration filter, in addition to the filtration flow rate, in order to suppress the generation of foreign matter such as thrombus, the function of allowing blood to pass smoothly without deviation in the entire area of ​​the filter that becomes the range of blood flow is also required. In order to allow blood to pass smoothly in the entire area of ​​the filter, the deviation of the OP of the fabric is required to be smaller. When there is a deviation in OP, the pressure loss varies depending on the position of the filter, which may cause the retention of blood that causes thrombus. If a fabric using fibers of normal thickness is used, there is almost no situation where the OP is inconsistent due to the misalignment of the silk due to the fabric organization, but the blood filtration filter of this embodiment is a fabric with a high opening rate using fine fibers, so the mesh is very coarse, and sometimes the warp and weft are misaligned during weaving (hereinafter also referred to as "mesh misalignment"). If this mesh misalignment occurs, the OP becomes inconsistent.

[0032] The blood filtration filter of the present embodiment can suppress the above-mentioned mesh misalignment by making the fabric structure into a plain weave or a three-page twill structure (2 / 1 twill and 1 / 2 twill), and further suppress the deviation of OP, so that blood can pass smoothly through the entire area of ​​the filter. In contrast, in the fabric structure, there are other structures such as twill structures (four-page twill structures such as 2 / 2 twill and 3 / 1 twill) in which the number of crossed threads is changed, and satin weaves called satin. However, these fabric structures have a large number of weft threads passing through the warp threads and a small number of crossing parts, so mesh misalignment occurs in fabrics using fine-diameter threads (fine fibers) as in the present embodiment, resulting in deviation of OP, and are therefore not suitable.

[0033] In addition, in the case of the 2 / 2 twill weave of four pages, in addition to the larger deviation of OP than the three-page twill weave, there is also a difference in the deviation of OP in the warp direction of the warp yarn extension and the weft direction of the weft yarn extension, and there is a tendency that the deviation of one of the warp and weft directions becomes larger relative to the other. In addition, in the case of the 1 / 3 (3 / 1) of four pages, there are fewer crossing parts compared with the plain weave and 2 / 1 twill weave, so the OP size tends to deviate. In contrast, in the case of the plain weave and three-page twill weave of the present embodiment, the deviation of the opening size is smaller, and the difference in the deviation of OP in the warp and weft directions is also smaller, so it is preferred. The difference in the deviation of OP in the warp and weft directions is smaller, which can suppress the generation of retention and allow blood to pass more smoothly.

[0034] For the blood filtration filter of the present embodiment, regarding the deviation of OP, the standard deviation of OP is preferably less than 3 μm. By making the standard deviation of OP less than 3 μm, the deviation of OP can be fully reduced, so that blood can pass smoothly. It should be noted that the standard deviation of OP is obtained in two directions of the silk (warp OP and weft OP), and the standard deviations of both are preferably less than 3 μm. In addition, the standard deviations of the warp and weft are preferably the same. The generation of retention can be suppressed and the blood can pass more smoothly.

[0035] In this embodiment, regarding the standard deviation of OP in each direction, OP is measured at 20 randomly selected points in the warp direction and the weft direction, and the standard deviation of OP in each of the warp direction and the weft direction is obtained from the respective 20 measured values. OP can be measured using a digital microscope.

[0036] The blood filtration filter of the present embodiment obtained by the above method can remove foreign matter such as thrombus without damaging the filtration flow of blood, and can therefore be used in various medical devices that require blood filtration, such as artificial heart-lung and hemodialysis devices. In addition, since the deviation of OP in the warp and weft directions is also small, a blood filtration filter in which the retention of blood and the generation of thrombus etc. are suppressed can be provided. It should be noted that, when the blood filtration filter of the present embodiment is used in medical equipment etc., it can also be used by forming a blood filtration filter component fixed by a supporting member such as a frame supporting the blood filtration filter of the present embodiment. The supporting member can be formed using a resin material etc. that can be used in a blood filtration device etc.

[0037] Example

[0038] Next, the embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0039] (Example 1)

[0040] A polyester (polyethylene terephthalate (PET)) monofilament with a wire diameter of 19 μm was woven into a 420 mesh plain weave fabric as the blood filtration filter of Example 1. The warp OP and weft OP of the prepared fabric were randomly measured at 20 points in the warp and weft directions using a digital microscope (RH-2000 manufactured by HIROX CO., LTD.), and the standard deviation of the OP in the warp and weft directions was calculated. At the measurement position of OP, the wire diameter was also measured at 20 points in the warp and weft directions. The opening rate was calculated as follows: the average values ​​of the measured values ​​of OP and wire diameter at 20 points in the warp and weft directions were calculated, and the respective average values ​​were used as the warp OP, weft OP, warp diameter, and weft diameter, and the above-mentioned opening rate was calculated using the above-mentioned calculation formula (1). These results are shown in Table 1.

[0041] (Example 2)

[0042] The blood filtration filter of Example 2 was woven in the same manner except that the fabric structure of Example 1 was changed to 2 / 1 twill structure (three-leaf twill structure), and the standard deviation of warp OP and weft OP was determined and the opening ratio was calculated in the same manner as in Example 1. These results are shown in Table 1.

[0043] (Comparative Example 1)

[0044] The blood filtration filter of Comparative Example 1 was woven in the same manner except that the fabric structure of Example 1 was changed to a 2 / 2 twill structure (one of the four-page twill structures), and the standard deviation of the warp OP and the weft OP was obtained in the same manner as in Example 1, and the opening ratio was calculated. These results are shown in Table 1.

[0045] (Example 3)

[0046] Liquid crystal polymer (LCP) monofilaments with a fiber diameter of 20 μm were used to weave a 420-mesh plain weave fabric as the blood filtration filter of Example 3.

[0047] (Example 4)

[0048] The blood filtration filter of Example 4 was made of PET monofilaments with a fiber diameter of 35 μm and woven into a 330-mesh plain weave fabric.

[0049] (Example 5)

[0050] The blood filtration filter of Example 5 was made of PET monofilaments with a fiber diameter of 33 μm and woven into a 305-mesh plain weave fabric.

[0051] (Example 6)

[0052] The blood filtration filter of Example 6 was made of PET monofilaments with a fiber diameter of 30 μm and woven into a 380-mesh plain weave fabric.

[0053] (Example 7)

[0054] The blood filtration filter of Example 7 was made of polyphenylene sulfide (PPS) monofilaments with a fiber diameter of 35 μm, woven into a 330-mesh 1 / 2 twill fabric.

[0055] (Example 8)

[0056] The blood filtration filter of Example 8 was made of polyester monofilament with a fiber diameter of 27 μm and woven into a 315-mesh 1 / 2 twill fabric.

[0057] (Comparative Example 2)

[0058] The blood filtration filter of Comparative Example 2 was made of PET monofilaments having a fiber diameter of 55 μm and woven into a 225-mesh plain weave.

[0059] (Comparative Example 3)

[0060] A PET monofilament with a fiber diameter of 35 μm was used to weave a 355-mesh 1 / 2 twill fabric as the blood filtration filter of Comparative Example 3.

[0061] The manufacturing conditions of the blood filtration filters of each embodiment and comparative example, the OP in the warp and weft directions (the average value measured at 20 points), the standard deviation of the warp OP and weft OP, and the opening ratio of each embodiment and comparative example calculated using the method shown in the above-mentioned Example 1 are shown in Table 1.

[0062] [Table 1]

[0063]

[0064] According to the above results, in all samples, the opening ratio can be achieved to be 30% or more and 50% or less, but in the blood filtration filters of Examples 1 and 2, the deviation of the warp OP and the weft OP is small, and the mesh misalignment is small. In contrast, in the blood filtration filter of Comparative Example 1, the deviation of the weft OP is larger than that of Examples 1 and 2, and the deviation of the warp OP is smaller than that of the weft OP, but larger than that of Examples 1 and 2. In addition, the difference between the deviations in the warp and weft directions of Comparative Example 1 is large, which is considerably larger than the difference between the warp and weft directions in Examples 1 and 2. Therefore, it can be seen that Comparative Example 1 does not satisfy the performance as a blood filtration filter.

[0065] In Example 3, in which the material is LCP, the opening ratio for achieving a sufficient blood filtration flow rate is also 30% or more, and the OP is of an appropriate size to remove foreign matter, and the plain weave structure has small variations in the OP.

[0066] The opening ratio of Examples 3 to 8 can also be 30% or more and 50% or less. In addition, the standard deviation of OP is less than 3 μm, and the variation of OP is also small.

[0067] The fiber diameter of Comparative Example 2 is greater than 40 μm and the mesh number is less than 300 meshes, so the opening rate is less than 30%, and sufficient filtration flow cannot be obtained, so it is not preferred in terms of filtration efficiency. For Comparative Example 3, although the conditions such as fiber diameter, mesh number, and organization are met, the opening rate is small, which is not preferred in terms of filtration efficiency.

Claims

1. A blood filtration filter, characterized in that: It is a mesh-like blood filter formed by resin fibers. The mesh number is more than 300 meshes. The opening ratio is 30% or more and 50% or less. The fiber has a fiber diameter of 10 μm or more and 40 μm or less, The fabric structure is plain weave or three-page twill weave.

2. The blood filtration filter according to claim 1, characterized in that: The standard deviation of OP (wire pitch) of the blood filtration filter is less than 3 μm.

3. The blood filtration filter according to claim 1, characterized in that: The blood filtration filter is formed from monofilament fibers.

4. The blood filtration filter according to claim 1, characterized in that: The OP (wire pitch) of the blood filtration filter is 20 μm or more and 50 μm or less.

5. A blood filtration filter component, characterized in that: The blood filtration filter comprises the blood filtration filter according to claims 1 to 4 and a supporting member for supporting the blood filtration filter.

Images