Medical guide wire

Abstract

To provide a medical guide wire that exerts excellent sliding property while ensuring adhesion of a coating layer.SOLUTION: A medical guide wire (1) includes: an elongated wire body (2) having flexibility; at least one intermediate layer (3) for coating a surface of the wire body (2); and an outermost layer (4) for coating a surface of the intermediate layer (3). The intermediate layer (3) is colored by including a pigment, where the concentration of the pigment is 50 wt% or more and 90 wt% or less based on the total intermediate layer (3).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a medical guidewire. [Background technology]

[0002] Conventionally, various medical guidewires used in the medical field have been known. For example, as described in Patent Document 1, a medical guidewire for use under an endoscope is known that is covered with a fluororesin tube having a spiral pattern that is color-coded in multiple colors so that the movement of the guidewire can be grasped through the fiberscope of the endoscope while ensuring smooth sliding within the catheter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-97662 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned guidewires covered with color-coded fluororesin tubes have excellent visibility under an endoscope. However, because the fluororesin tube is not chemically bonded to the metal wire of the guidewire, when used as a guidewire to be passed through a puncture needle in ultrasonic endoscopic puncture procedures, which have become increasingly popular in recent years, there is a problem that part of the fluororesin tube peels off and falls off upon contact with the tip of the hollow puncture needle, making it difficult to use as a guidewire to be passed through a puncture needle.

[0005] Also known is a guidewire that is formed by coating a resin base layer and a fluororesin layer by a coating method on a metal wire that is the core material of the guidewire. However, such a guidewire is also not designed to slide against a metal member having a sharp tip, such as a puncture needle, and there is a concern that the fluororesin layer coated on the resin base layer will peel off and fall off upon contact with the tip of a hollow puncture needle, making it difficult to use as a guidewire for passing through a puncture needle.

[0006] Due to these problems, metal wires that are not covered with a fluororesin tube or have no coating layer are used as guide wires to be passed through puncture needles in ultrasonic endoscopic puncture procedures. However, metal wires have poor slipperiness and are difficult to insert through hollow puncture needles.

[0007] The present invention has been made to solve such problems, and an object of the present invention is to provide a medical guidewire that exhibits excellent lubricity while ensuring adhesion of the coating layer. [Means for solving the problem]

[0008] The above-mentioned object of the present invention is achieved by a medical guidewire comprising a long, flexible wire body, at least one intermediate layer covering the surface of the wire body, and an outermost layer covering the surface of the intermediate layer, the intermediate layer being colored by containing a pigment, the concentration of the pigment being 50 wt% or more and 90 wt% or less of the entire intermediate layer.

[0009] In this medical guidewire, the concentration of the pigment is preferably 55 wt % or more and 85 wt % or less with respect to the entire intermediate layer.

[0010] The intermediate layer may also be configured to include a first region containing a first pigment and a second region containing a second pigment having a different color than the first pigment.

[0011] The average particle size of the pigment is preferably in the range of 0.05 μm to 2 μm, and the thickness of the intermediate layer is preferably in the range of 1 μm to 30 μm.

[0012] The intermediate layer preferably contains a binder resin made of a polyimide resin, the outermost layer preferably is made of a fluorine-based resin material, and the outermost layer is preferably fused to a surface of the intermediate layer. Effect of the Invention

[0013] According to the present invention, it is possible to provide a medical guidewire that exhibits excellent lubricity while ensuring adhesion of the coating layer. [Brief description of the drawings]

[0014] [Figure 1] 1 is an enlarged schematic cross-sectional view of a main portion of a medical guidewire according to an embodiment of the present invention. [Diagram 2] FIG. 2(a) is an enlarged plan view of a main portion showing a modified example of the medical guidewire in FIG. 1, and FIG. 2(b) is an enlarged sectional view of the main portion taken along the line AA of FIG. [Diagram 3] 1, and FIG. 5(b) is an enlarged sectional view of the main part taken along line BB of FIG. [Figure 4] 1. (a) and (b) are both enlarged plan views of a main portion showing still another modified example of the medical guidewire in FIG. [Diagram 5] 1. FIG. 4 is an enlarged schematic cross-sectional view of a main portion showing a modified example of the medical guidewire in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A medical guidewire 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings. Note that each drawing is partially enlarged or reduced in order to facilitate understanding of the configuration. FIG. 1 is an enlarged schematic cross-sectional view of a main portion of a medical guidewire 1 according to an embodiment of the present invention. The medical guidewire 1 according to the present invention is, for example, a guidewire to be passed through a hollow puncture needle in an ultrasonic endoscopic puncture procedure or a guidewire to be inserted into a catheter, and includes a wire body 2, an intermediate layer 3, and an outermost layer 4.

[0016] The wire body 2 is a long, flexible linear member. The wire body 2 can be made of various materials that are conventionally used as core materials for medical guidewires, but is preferably made of a metal material. For example, the wire body 2 can be made of stainless steel (e.g., all types of SUS, such as SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429, SUS430F, and SUS302). When stainless steel is used as the material for the wire body 2, the medical guidewire 1 can have better pushability and torque transmission properties.

[0017] Also, an alloy exhibiting pseudoelasticity (including a superelastic alloy) can be used as the material for the wire body 2. In particular, when the wire body 2 is made of a superelastic alloy, the medical guidewire 1 has sufficient flexibility and recovery against bending throughout, and is improved in its ability to follow complex curves and bends, resulting in better operability. Furthermore, even if the wire body 2 is repeatedly curved and bent, the wire body 2 does not develop a bending habit due to its recovery, so that it is possible to prevent a decrease in operability due to the wire body 2 developing a bending habit during use of the medical guidewire 1.

[0018] Pseudoelastic alloys include those that have any shape of stress-strain curve under tensile load, and those that have or do not have clearly measurable transformation points such as As, Af, Ms, and Mf. They also include all alloys that undergo significant deformation when subjected to stress and return to almost their original shape when the stress is removed.

[0019] Preferred compositions of the superelastic alloy include Ni-Ti alloys such as Ni-Ti alloys containing 49 to 52 atomic % Ni, Cu-Zn alloys containing 38.5 to 41.5 weight % Zn, Cu-Zn-X alloys containing 1 to 10 weight % X (X is at least one of Be, Si, Sn, Al, and Ga), Ni-Al alloys containing 36 to 38 atomic % Al, etc. Among these, the above Ni-Ti alloys are particularly preferred.

[0020] Moreover, a cobalt-based alloy can be used as the material of the wire body 2. When the wire body 2 is made of a cobalt-based alloy, the medical guide wire 1 has particularly excellent torque transmission properties and is extremely unlikely to suffer from problems such as buckling. Any cobalt-based alloy may be used as long as it contains Co as a constituent element, but it is preferable to use an alloy containing Co as a main component (Co-based alloy: an alloy in which the content of Co is the highest by weight among the elements constituting the alloy), and it is more preferable to use a Co-Ni-Cr-based alloy. By using an alloy with such a composition, the above-mentioned effects become even more remarkable. In addition, an alloy with such a composition has a high elastic modulus and can be cold-formed even with a high elastic limit. Due to the high elastic limit, it can be made small in diameter while sufficiently preventing the occurrence of buckling, and can have sufficient flexibility and rigidity to be inserted into a predetermined site.

[0021] Moreover, the wire body 2 may be made of, for example, a piano wire in addition to the above-mentioned materials.

[0022] Various configurations can be adopted for the wire body 2. For example, the wire body 2 may be formed by a single steel material, or a single linear steel material may be folded and then twisted to form the wire body 2. The wire body 2 may also be formed by twisting a plurality of linear steel materials, or by twisting linear steel materials and linear resin members. Furthermore, various configurations can be adopted, such as a material in which the center part and the surface part are made of different materials (a two-layer structure, for example, a member in which the surface part is formed by coating the outer surface of the central part made of metal with a thermosetting resin). The total length of the wire body 2 is not particularly limited, but is preferably about 2000 to 5000 mm.

[0023] The wire body 2 may be configured so that its outer diameter is substantially constant, or the tip portion may be tapered so that its outer diameter decreases toward the tip. When the tip portion of the wire body 2 is configured so that its outer diameter decreases toward the tip, the rigidity (bending rigidity, torsional rigidity) of the wire body 2 can be gradually decreased toward the tip, and as a result, the medical guidewire 1 has good passability through stenosis and flexibility at the tip portion, improving tracking ability and safety, and preventing bending, etc., which is preferable.

[0024] The wire body 2 may be constructed by connecting the first wire body 2 constituting the tip portion and the second wire body 2 constituting the intermediate portion and proximal portion by welding or the like. When the wire body 2 is constructed by the first wire body 2 and the second wire body 2, it is preferable to set the diameter of the first wire body 2 to be smaller than the diameter of the second wire body 2. It is also preferable to configure the connecting portion to have a tapered shape so that the first wire body 2 and the second wire body 2 are smoothly connected. Even when the wire body 2 is constructed in this way, the rigidity (bending rigidity, torsional rigidity) of the wire body 2 can be gradually decreased toward the tip, and as a result, the medical guide wire 1 has good passability and flexibility through a stenosis at the tip portion, improving tracking ability and safety, and preventing bending, etc., which is preferable.

[0025] The intermediate layer 3 is configured to cover the surface of the wire body 2, and is made of a material containing a pigment and a binder resin. The pigment contained in the intermediate layer 3 is a coloring agent, and is used to impart color to the intermediate layer 3. The pigment may be either an inorganic pigment or an organic pigment, but it is preferable to adopt a pigment having excellent heat resistance. As the pigment, carbon black, titanium oxide, phthalocyanine blue, mica, nickel titanium yellow, Prussian blue, Milory blue, cobalt blue, ultramarine, viridian, etc. can be used. Note that one type of pigment may be used alone, or two or more types may be used in combination (particularly mixed). In addition, the average particle size of the pigment is not particularly limited, but is preferably set to a range of 0.05 μm to 2 μm, and more preferably set to a range of 0.1 μm to 1.5 μm.

[0026] The type of binder resin contained in the intermediate layer 3 is not particularly limited, and examples thereof include polysulfone, polyimide, polyether ether ketone, polyarylene ketone, polyphenylene sulfide, polyarylene sulfide, polyamide imide, polyether imide, polyimide sulfone, polyaryl sulfone, polyaryl ether sulfone, polyester, polyether sulfone, etc. In particular, polyimide-based resins such as polyimide, polyamide imide, polyether imide, and polyimide sulfone can be preferably used. By using such a material as the binder resin, the adhesion between the wire body 2 and the outermost layer 4 can be effectively improved.

[0027] The thickness of the intermediate layer 3 is not particularly limited, but is preferably set to 1 μm or more from the viewpoint of making the color stand out. Also, from the viewpoint of configuring the medical guidewire not to be too thick, it is preferably set to 30 μm or less. More preferably, the intermediate layer 3 is preferably configured to have a thickness in the range of 2 μm to 20 μm.

[0028] In the present invention, the pigment concentration is set to be in the range of 50 wt% to 90 wt% based on the entire intermediate layer 3. More preferably, the pigment concentration is set to be in the range of 55 wt% to 85 wt%, and even more preferably, in the range of 60 wt% to 85 wt% based on the entire intermediate layer 3. By setting the pigment concentration in this range, the surface area of ​​the surface of the intermediate layer 3 (the surface in contact with the outermost layer 4) is increased, the anchor effect on the outermost layer 4 is increased, and the adhesive strength of the outermost layer 4 to the intermediate layer 3 is dramatically improved. In addition, by setting the pigment concentration in this range, the hardness gap between the wire body 2 and the intermediate layer 3 can be reduced, which is presumably why shear stress applied from the outside of the guidewire, such as when the tip of a puncture needle passes through the guidewire, is less likely to concentrate on the interface between the wire body 2 and the intermediate layer 3.

[0029] The method of forming the intermediate layer 3 by coating the surface of the wire body 2 with a material composed of the above-mentioned pigment and binder resin is not particularly limited, and various methods can be used. For example, the intermediate layer 3 can be formed by applying a solution prepared by mixing the above-mentioned pigment and binder resin with an appropriate solvent to the wire body 2, and then drying the solution to volatilize the solvent. Note that the material contained in the intermediate layer 3 is not limited to the above-mentioned pigment and binder resin, and may be configured to contain, for example, a fluorine-based resin or various other additives.

[0030] The outermost layer 4 is configured to cover the intermediate layer 3 disposed on the surface of the wire body 2, and is preferably formed of a transparent material. The material constituting the outermost layer 4 is preferably, for example, a fluororesin material having lubricity. Examples of such fluororesin materials include tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA, melting point 300 to 310°C), polytetrafluoroethylene (PTFE, melting point 330°C), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point 250 to 280°C), ethylene-tetrafluoroethylene copolymer (ETFE, melting point 260 to 270°C), polyvinylidene fluoride (PVDF, melting point 160 to 180°C), polychlorotrifluoroethylene (PCTFE, melting point 210°C), tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinylether copolymer (EPE, melting point 290 to 300°C), and copolymers containing these polymers. Among these, PFA, PTFE, FEP, ETFE, and PVDF are preferred because they have excellent sliding properties.

[0031] The thickness of the outermost layer 4 is not particularly limited, but is usually from 2 μm to 30 μm, preferably from 3 μm to 25 μm, and particularly preferably from 4 μm to 20 μm, in terms of dry thickness.

[0032] The method of forming the outermost layer 4 by coating the surface of the intermediate layer 3 with the above-mentioned resin material is not particularly limited, and various methods can be used. For example, the wire body 2 on which the intermediate layer 3 has been formed is immersed in a solution prepared using the above-mentioned resin material and an appropriate solvent, dried, and then heat-treated to fuse the outermost layer 4 onto the intermediate layer 3. The heat treatment can be performed, for example, by using a chamber-type heat treatment device to apply heat from the outside of the outermost layer 4 formed on the wire body 2. In addition, when the wire body 2 is formed from, for example, a metal material that easily conducts electricity, a voltage can be applied to both ends of the wire body 2 to heat the wire body 2, and the outermost layer 4 arranged to cover the surface of the wire body 2 can be melted by the heat, thereby fusing the outermost layer 4 onto the intermediate layer 3.

[0033] As described above, the medical guidewire 1 according to this embodiment is configured so that the intermediate layer 3 is interposed between the wire body 2 and the outermost layer 4, and the concentration of the pigment contained in the intermediate layer 3 is 50 wt % or more and 90 wt % or less with respect to the entire intermediate layer 3. With such a configuration, it is possible to achieve extremely high adhesion between the outermost layer 4 and the intermediate layer 3, and even when used as a guidewire to be passed through a puncture needle in ultrasonic endoscopic puncture surgery, it is possible to effectively prevent the outermost layer 4 from peeling off due to contact with the tip of the hollow puncture needle.

[0034] Furthermore, since the medical guidewire 1 according to the present invention has an outermost layer 4 having lubricity formed from a fluorine-based resin material or the like, it exhibits extremely high slipperiness and can ensure good sliding properties between the medical guidewire 1 and the inner wall of a puncture needle or catheter in ultrasonic endoscopic puncture surgery.

[0035] Here, in the configuration shown in Fig. 1, the intermediate layer is configured to have one layer, but for example, as shown in Fig. 2(a) which is an enlarged plan view of a main part, and Fig. 2(b) which is an enlarged sectional view of a main part at section AA in Fig. 2(a), the intermediate layer may be configured to have a first region 31 containing a first pigment and a second region 32 containing a second pigment having a color different from the first pigment. In the medical guidewire shown in Fig. 2, the second region 32 is provided on the first region 31 so as to form a two-layer structure of the intermediate layer. Moreover, the second region 32 is provided on the first region 31 so as to form a spiral pattern along the longitudinal direction of the medical guidewire.

[0036] Such an intermediate layer 3 is formed, for example, by mixing a first pigment, a binder resin and a solvent to prepare a first solution, and separately mixing a second pigment, a binder resin and a solvent to prepare a second solution, applying the first solution to the wire body 2 and drying it to form a first region 31, and then applying a second solution in a spiral shape on the first region 31 and drying it to form a second region 32.

[0037] Thus, even in the case of an intermediate layer 3 having the first region 31 and the second region 32, the above-mentioned effect of improving adhesion can be obtained by configuring the concentration of the pigment contained in the intermediate layer 3 (the combined pigment concentration of the first pigment and the second pigment) to be 50 wt % or more and 90 wt % or less with respect to the entire intermediate layer 3. Furthermore, by configuring the intermediate layer 3 to have the first region 31 and the second region 32 of different colors, the movement of the guidewire can be easily grasped through a fiberscope of an endoscope or the like, and therefore the medical guidewire shown in Fig. 2 has excellent visibility.

[0038] 2 shows the configuration of the intermediate layer 3 having a two-layer structure in which the second region 32 having a spiral pattern is formed on the first region 31, but as shown in the enlarged plan view of the main part of FIG. 3(a) and the enlarged sectional view of the main part of FIG. 3(b) of the cross section BB in FIG. 3(a), the first region 31 and the second region 32 may be configured as a double spiral structure (a spiral pattern is formed by one layer of the intermediate layer 3) in which the first region 31 and the second region 32 are alternately arranged on the wire body 2 along the longitudinal direction of the wire body 2. When the intermediate layer 3 is configured to have the first region 31 and the second region 32 having different colors, the configuration is not limited to the spiral pattern as shown in FIG. 2 or 3. For example, the second region 32 may be formed in a dot shape as shown in the enlarged plan view of the main part of FIG. 4(a), or the ring-shaped first region 31 and the second region 32 may be arranged alternately along the longitudinal direction of the wire member as shown in the enlarged plan view of the main part of FIG. 4(b).

[0039] The inventors of the present invention created prototypes of embodiments (Examples 1 to 4) and comparative examples (Comparative Examples 1 to 4) related to the medical guidewire of the present invention and conducted tests to confirm the above-mentioned effects (effects related to improved adhesion), which are described below.

[0040] First, the structures of Examples 1 to 4 and Comparative Examples 1 to 4 will be described. As shown in Fig. 2(a) and (b), Examples 1 to 4 and Comparative Examples 1 to 4 are configured by forming an intermediate layer 3 (an intermediate layer 3 having a first region 31 and a second region 32) having a two-layer structure on a wire body 2, and forming an outermost layer 4 on the intermediate layer 3. In all of Examples 1 to 4 and Comparative Examples 1 to 4, a metal wire rod having a diameter of 0.55 mm (material: Ni-Ti alloy manufactured by Furukawa Techno Material Co., Ltd.) is used as the wire body 2. In all of Examples 1 to 4 and Comparative Examples 1 to 4, the outermost layer 4 is configured by using a tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA). The thickness of the outermost layer 4 is 10 µm.

[0041] The first region 31 constituting the intermediate layer 3 has a thickness of 4 μm. The second region 32 formed on the first region 31 has a thickness of 8 μm. The second region 32 is configured so that its dimension in the longitudinal direction of the wire body 2 is 3 mm. When viewed in the longitudinal direction of the wire body 2, the distance between adjacent second regions 32 is 6 mm.

[0042] In addition, for the intermediate layer 3, the pigment and binder resin contained in the first region 31 and the second region 32 were changed in various ways for each of Examples 1 to 4 and Comparative Examples 1 to 4, and the pigment concentration relative to the entire intermediate layer 3 (first region 31 and second region 32) was changed. Details of the type of binder resin, type of pigment, and pigment concentration contained in the intermediate layer 3 (first region 31 and second region 32) are shown in Table 1 below. Note that the pigment concentration in Example 1 is 85 wt%, the pigment concentration in Example 2 is 70 wt%, the pigment concentration in Example 3 is 60 wt%, and the pigment concentration in Example 4 is 50 wt%. Furthermore, the pigment concentration in Comparative Example 1 is 30 wt%, the pigment concentration in Comparative Example 2 is 40 wt%, the pigment concentration in Comparative Example 3 is 95 wt%, and the pigment concentration in Comparative Example 4 is 40 wt%.

[0043] [Table 1]

[0044] For the guidewires according to Examples 1 to 4 and Comparative Examples 1 to 4 configured as described above, a hollow puncture needle (Terumo Corporation, NEOLUS (1.20×38 mm)) actually used in ultrasonic endoscopic puncture surgery was inserted into the guidewire to conduct an adhesion confirmation test to check whether the outermost layer 4 peels off. More specifically, each guidewire was inserted from the base end of a hollow puncture needle placed horizontally, and the guidewire was pulled out 50 mm from the tip of the puncture needle at an angle of 45 degrees upward and set in place. Thereafter, the guidewire was pulled out from the tip side of the puncture needle to The guidewire was pulled toward the base end at a uniform speed. The guidewire was checked using a microscope to see whether or not peeling of the outermost layer 4 had occurred. The results are shown in Table 2 below. Regarding the adhesion check results, the case where the outermost layer 4 had peeled off was marked with "X", the case where the outermost layer 4 had not peeled off but had peeled off in layers was marked with "△", the case where the outermost layer 4 was scratched but not peeled off or fallen off was marked with "◯", and the case where the outermost layer 4 was not scratched or peeled off was marked with "◎".

[0045] The inventors also conducted a visibility confirmation test for each of Examples 1 to 4 and Comparative Examples 1 to 4, and the results are also shown in Table 2. The visibility confirmation test was conducted by inserting each guidewire into a PTFE cannula and observing the movement of the guidewire under an endoscopic fiberscope. In Table 2, the test confirmation results are marked with "X" when it was not possible to confirm that the guidewire was moving, and "△" when it was possible to confirm that the guidewire was moving but it was unclear. Also, the case where the movement of the guidewire was clearly confirmed is marked with "◎".

[0046] [Table 2]

[0047] As shown in the adhesion confirmation results in Table 2 above, it can be confirmed that the outermost layer 4 does not peel off and fall off in Examples 1 to 4 and Comparative Example 3, in which the concentration of the pigment contained in the intermediate layer 3 (first region 31 and second region 32) is in the range of 50 wt% or more with respect to the entire intermediate layer 3. In particular, it can be seen that in Examples 1, 2, and 3, in which the pigment concentration is in the range of 60 wt% or more and 85 wt% or less with respect to the entire intermediate layer 3, there is no peeling or falling off of the outermost layer 4, and the adhesion of the outermost layer 4 is extremely excellent.

[0048] On the other hand, in Comparative Examples 1, 2, and 4, in which the pigment concentration was 40 wt % or less relative to the entire intermediate layer 3, parts of the outermost layer 4 fell off, confirming that the adhesion of the outermost layer 4 was poor.

[0049] Furthermore, from the adhesion confirmation results in Table 2, it is believed that the lower limit of the pigment concentration at which the outermost layer can withstand use without falling off is 50 wt% in Example 4. In particular, the lower limit of the pigment concentration at which the adhesion of the outermost layer 4 is high is believed to exist between 50 wt% in Example 3 and 60 wt% in Example 4, and it is presumed that the arithmetic mean value of both, 55 wt%, is the boundary between them. Therefore, in order to sufficiently ensure adhesion between the intermediate layer 3 and the outermost layer 4, it can be said that the concentration of the pigment contained in the intermediate layer 3 is preferably set to 55 wt% or more of the entire intermediate layer 3.

[0050] From the results of adhesion confirmation in Table 2, the upper limit of the pigment concentration at which the outermost layer can withstand use without falling off is considered to be 95 wt% in Comparative Example 3. However, in the case of Comparative Example 3, the amount of pigment contained in the intermediate layer 3 is excessive, which may cause problems in the adhesion between the wire body 2 and the intermediate layer 3 (the results of adhesion confirmation in Table 2 are marked as “△ to ×” because there is a possibility of problems in the adhesion between the wire body 2 and the intermediate layer 3). Therefore, the upper limit of the pigment concentration at which the adhesion between the wire body 2 and the intermediate layer 3 is excellent and the adhesion of the outermost layer 4 is high is considered to be between 85 wt% in Example 1 and 95 wt% in Comparative Example 3, and the arithmetic mean value of both, 90 wt%, is presumed to be the boundary. In other words, in order to sufficiently secure the adhesion between the wire body 2 and the intermediate layer 3 and the adhesion between the intermediate layer 3 and the outermost layer 4, it is preferable to set the concentration of the pigment contained in the intermediate layer 3 to 90 wt% or less of the entire intermediate layer 3.

[0051] Furthermore, from the visibility confirmation results in Table 2, it can be seen that Examples 1 to 4 and Comparative Example 3, in which the concentration of the pigment contained in the intermediate layer 3 (first region 31 and second region 32) is in the range of 50 wt % or more with respect to the entire intermediate layer 3, all have good visibility in which the movement of the guidewire can be clearly confirmed. On the other hand, it can be seen that in Comparative Examples 1, 2, and 4, in which the pigment concentration is 40 wt % or less with respect to the entire intermediate layer 3, the movement of the guidewire cannot be confirmed or is unclear.

[0052] From the above, it can be seen that by setting the concentration of the pigment contained in the intermediate layer 3 (first region 31 and second region 32) in the range of 50 wt% or more and 90 wt% or less with respect to the entire intermediate layer 3, it is possible to improve visibility under the fiberscope of an endoscope, and further, it is possible to ensure sufficient adhesion of the outermost layer 4.

[0053] The medical guidewire 1 according to the present invention has been described above, but the specific configuration is not limited to the above embodiment. For example, as shown in the cross-sectional view of FIG. 5, the medical guidewire 1 may be configured by spirally winding the wire 5 on the surface of the outermost layer 4. The medical guidewire 1 shown in FIG. 5 shows a configuration in which the wire 5 is wound around the medical guidewire shown in FIG. 2. The wire 5 is preferably formed from the same material as the material forming the outermost layer 4. Before being wound around the outermost layer 4, the wire 5 is formed to have a substantially uniform thickness along its longitudinal direction, and the maximum diameter of the wire 5 is preferably in the range of, for example, 10 μm to 200 μm, and more preferably in the range of 80 μm to 200 μm. Here, the pitch is a concept representing the center-to-center distance between adjacent wire rods 5 in the longitudinal direction of the wire body 2, as shown in the cross-sectional view of Fig. 5, and in Fig. 5, the wire rod 5 is wound spirally so that the center-to-center distance (pitch) between the wire rods 5 is equal. The center-to-center distance (pitch) between the wire rods 5 can be set to any dimension, for example, 15 µm to 5000 µm, preferably 30 µm to 1000 µm, and particularly preferably 50 µm to 700 µm. The center-to-center distance (pitch) between the wire rods 5 may be configured to be partially different.

[0054] The method for winding the wire 5 on the outermost layer 4 is not particularly limited, and examples thereof include a method for winding the wire 5 using a covering device used for producing a covered yarn.

[0055] The wire 4 wound in a spiral shape on the outermost layer 4 is fused to the outermost layer 4 over its entire area to be integrated. For example, a method of fusing the wire 5 to the outermost layer 4 may be used in which the wire 5 is spirally wound around the outer surface of the outermost layer 4, and then the wire 5 and the outermost layer 4 are melted by heating to fuse the wire 5 to the surface of the outermost layer 4. For example, a chamber-type heat treatment device may be used to apply heat from the outside of the wire 4 wound around the outermost layer 4 on the wire body 2. For example, when the wire body 2 is made of a metal material that easily conducts electricity, a voltage may be applied to both ends of the wire body 2 to heat the wire body 2, and the outermost layer 4 and wire 5 on the wire body 2 may be melted by the heat, thereby fusing the wire 5 to the outermost layer 4. In addition, when the wire 5 is provided on the outermost layer 4, the heat treatment performed when forming the outermost layer 4 on the intermediate layer 3 described above may be omitted, and the heat treatment performed after placing the wire 5 on the outermost layer 4 may simultaneously fuse the outermost layer 4 to the intermediate layer 3 and the wire 5 to the outermost layer 4.

[0056] Providing such wire 5 further improves the durability of the outermost layer 4, and when the medical guidewire 1 is inserted into a hollow puncture needle or catheter, the part that comes into contact with the inner wall of the hollow puncture needle is the outermost part (top) of the wire 5, making it possible to reduce the contact area between the medical guidewire 1 and the hollow puncture needle, catheter, etc., and thus ensuring even higher slidability. In particular, by making the wire 5 from a fluorine-based resin material, even higher slidability can be ensured.

[0057] 5, the wire 5 heat-fused onto the outermost layer 4 has a cross-sectional shape of a semicylindrical lens or a plano-convex lens (a capital letter "D" shape), and the height of the wire 5 after heat fusion (the dimension from the surface of the outermost layer 4 to the top of the wire) is preferably configured to be in the range of 4 μm to 80 μm. By configuring the wire 5 after fusion to have such a numerical range, particularly a height of 6 μm or more, when the medical guidewire 1 is moved inside a hollow puncture needle or catheter, the lubricity is improved by point contact, and further, vibrations caused by the movement of the uneven parts are transmitted to the fingertips of the user (practitioner) of the medical guidewire, so that the insertion status can be grasped from sensory information caused by such specific vibrations in addition to visual information from the endoscope and normal insertion sensory information, thereby improving user convenience.

[0058] In the configuration shown in FIG. 5, one wire 5 is wound in a spiral shape on the outermost layer 4, but, for example, two wires 5 of different thicknesses may be wound in a spiral shape (double spiral shape) on the outermost layer 4. [Explanation of symbols]

[0059] 1 Medical guidewires 2 Wire body 3. Middle Tier 31 First area 32 Second area 4 Outermost layer 5 wire rod

Claims

1. A medical guide wire, A wire body having an elongated outer shape, Having a first region and a second region, an intermediate layer covering the wire body, The intermediate layer comprises a light-transmitting resin layer covering the intermediate layer, The first region and the second region have different colors from each other. The second region is arranged in multiple locations at intervals along the longitudinal direction in a cross-section of the medical guidewire. A medical guide wire in which the dimension of each second region along the longitudinal direction is smaller than the distance between adjacent second regions in the longitudinal direction.

2. The medical guide wire according to claim 1, wherein the distance between adjacent second regions in the longitudinal direction is substantially twice the dimension of each second region along the longitudinal direction.

3. The medical guide wire according to claim 1 or 2, wherein the proportion of the second region in the longitudinal direction on the guide wire body is substantially 1 / 3.

4. The medical guide wire according to claim 2, wherein the dimension of each second region along the longitudinal direction is 3 mm, and the distance between adjacent second regions in the longitudinal direction is 6 mm.

5. The medical guide wire according to any one of claims 1 to 4, wherein the second region is arranged in a spiral, dot, or ring shape along the longitudinal direction.

6. The resin layer has a surface with an uneven surface in which recesses and protrusions are alternately formed along the longitudinal direction in the cross-section, The medical guide wire according to any one of claims 1 to 5, wherein in the cross-section, the width of the second region is wider than the width of the protrusion.

7. The medical guide wire according to claim 6, wherein, in the longitudinal direction, the distance between adjacent second regions and the distance between adjacent protrusions are configured to be different dimensions.

8. The wire body is made of a metal wire made of a Ni-Ti alloy, The aforementioned resin layer is composed of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, The aforementioned intermediate layer is colored by containing a pigment and also contains a binder resin. The aforementioned pigment includes carbon black or titanium dioxide. The binder resin comprises polyamide-imide or polyether-imide. A medical guide wire according to any one of claims 1 to 7, wherein the wire body and the resin layer are not in direct contact.

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