CN211863554U

CN211863554U - Catheter sheath

Info

Publication number: CN211863554U
Application number: CN202020069090.0U
Authority: CN
Inventors: 许坚; 王平; 范凯燕
Original assignee: Shenzhen Neich Enterprise Co ltd
Current assignee: Shenzhen Neich Enterprise Co ltd
Priority date: 2020-01-13
Filing date: 2020-01-13
Publication date: 2020-11-06
Anticipated expiration: 2030-01-13

Abstract

The utility model belongs to the technical field of medical instrument, especially, relate to a catheter sheath, including the hemostasis valve, the sheath pipe, collateral branch pipe and three-way valve, the sheath pipe is by past outer inlayer in proper order, intermediate level and outer canning compound molding, the second end of sheath pipe is provided with radial convergent sheath tube end, second end at the sheath pipe, outer axial length is less than the axial length of inlayer, the axial length in intermediate level is greater than outer axle' to length, and the axial length in intermediate level is less than or equal to the axial length of inlayer, the terminal surface and the outer terminal surface of sheath tube end meet, the inner wall fixed connection of sheath tube end is in the inlayer, and the sheath tube end chooses for use and makes the shaping than the soft material of sheath pipe. Use this technical scheme to solve among the prior art sheath's sheath pipe can't compromise pliability and bending resistance, lead to sheath pipe external diameter great under the prerequisite of guaranteeing intensity to in the sheath product of current, sheath pipe head end is the same with the shaft material, can't adjust the problem of head end material hardness.

Description

Catheter sheath

Technical Field

The utility model belongs to the technical field of medical instrument, especially, relate to a catheter sheath.

Background

Percutaneous Coronary Intervention (PCI) refers to a treatment method for improving the perfusion of the blood flow of the cardiac muscle by opening the narrow or even occluded Coronary artery lumen through the cardiac catheter technique. Commonly used interventional routes in PCI are the femoral and radial arteries, namely: the interventional device is passed through the femoral or radial artery to the distal end of the vessel. In the process of establishing a vascular access, an introducer sheath is needed, and a guide wire, a catheter and other instruments are inserted into a blood vessel through a sheath lumen of the introducer sheath.

The main purposes for placing the catheter sheath are:

1. because of the hemostatic valve, no bleeding occurs in the operation process;

2. the injury to the vessel wall is small, and the catheter sheath is relatively stable when being placed in the blood vessel, so that the injury to the vessel wall when the catheter repeatedly enters and exits and twists can be avoided;

3. avoiding local pain or spasm when the catheter is pulled or replaced.

The inner diameter of the sheath lumen of the currently common sheath is 4F-8F (1F ═ 0.33mm), and in order to keep the flexibility of the sheath and make the friction of the sheath lumen wall small, the sheath is usually made of a single-layer plastic pipe, and the sheath made of the single-layer plastic pipe usually has the following problems:

1. the flexibility and the folding resistance of the pipe with the single-layer structure cannot be considered at the same time;

2. the strength of the pipe is ensured, the wall thickness of the sheath tube is usually more than 200 mu m, and the outer diameter of the sheath tube is larger under the condition of ensuring the inner cavity, so that the sheath tube is not suitable for the application of small blood vessels or blood vessels in a snuff bottle area;

3. in the existing conduit sheath product, the head end of the sheath tube is made of the same material as the tube body, the hardness of the material of the head end cannot be adjusted, and the hard head end easily damages blood vessels.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a conduit sheath aims at solving among the prior art conduit sheath's sheath pipe and can't compromise pliability and folding resistance, leads to the sheath pipe external diameter great under the prerequisite of proof strength to in the current conduit sheath product, sheath tube head end is the same with the shaft material, can't adjust the problem of head end material hardness.

In order to achieve the above object, the utility model adopts the following technical scheme: a catheter sheath comprises a hemostatic valve, a sheath tube, a side branch tube and a three-way valve, wherein the hemostatic valve is provided with a main channel and a side channel which are mutually communicated, a first end of the sheath tube is communicated with the main channel, the central axis of the sheath tube is coaxial with the main channel, a first end of the side branch tube is communicated with the side channel, a second end of the side branch tube is communicated with the three-way valve, the sheath tube is formed by sequentially outwards-arranged inner layer, middle layer and outer layer sheath in a composite mode, the inner layer and the outer layer are both made of polymer material layers, the middle layer is a metal wire layer, a radially-tapered sheath tube head end is arranged at the second end of the sheath tube, the axial length of the outer layer is smaller than that of the inner layer, the axial length of the middle layer is larger than that of the outer layer, the axial length of the middle layer is smaller than or equal to that of the inner layer, the end face of, and the head end of the sheath tube is made of a material softer than the sheath tube.

Further, the maximum outer diameter of the head end of the sheath tube is smaller than the outer diameter of the outer layer, the arc transition is formed at the joint of the head end of the sheath tube and the outer layer, and the inner diameter of the head end of the sheath tube is equal to the inner diameter of the inner layer.

Further, the maximum outer diameter of the sheath head end is equal to the outer diameter of the outer layer, and the inner diameter of the sheath head end is equal to the inner diameter of the inner layer.

Furthermore, the end face of the head end of the sheath tube is connected with the end face of the second end of the outer layer and is bonded or welded and fixed, and the inner wall of the head end of the sheath tube is bonded or welded and fixed on the inner layer.

Further, the position of the tube body of the sheath tube close to the head end of the sheath tube is set to be an arc-shaped bend angle.

Furthermore, the metal wire in the middle layer is spirally wound on the inner layer, and the inner wall of the outer layer is welded and fixed on the inner layer.

Furthermore, the metal wires in the middle layer are woven to form a woven mesh to cover the inner layer, and the inner wall of the outer layer is welded and fixed on the inner layer.

Further, the inner layer is made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyurethane, nylon, polyether block polyamide or polyethylene, and the outer layer is made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyurethane, nylon, polyether block polyamide or polyethylene.

Further, the sheath tip material may be made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyurethane, nylon, polyether block polyamide, or polyethylene.

Further, a developer is mixed and added in the inner layer; and/or, developer is mixed and added in the outer layer; and/or, a developer is mixed and added in the manufacturing material of the sheath tube head end.

The utility model has the advantages that:

the utility model provides a conduit sheath adopts three-layer composite structure, inlayer and skin all adopt macromolecular material, carry out biaxial stretching and the in-process that obtains the even ultra-thin wall pipe structure of wall thickness to inlayer and skin, the material pipe wall attenuation, and its axial and radial strength can not reduce too much, so just improved the crooked compliance of sheath pipe to the intermediate level has been embedded between inlayer and skin, the intermediate level adopts the wire to make, the intensity of sheath pipe has further been improved when not increasing sheath pipe external diameter. Simultaneously, in order to avoid the pipe sheath to cause the injury to the vascular inner wall in carrying out the intubate operation in-process, therefore sheath tube head end has been add at the second end of sheath pipe, it has the tapering shape to adapt to the intubate better and removes the process to utilize sheath tube head end, and, through the second end position department inlayer that will design the sheath pipe, the intermediate level, length ratio between the skin carries out fixed connection with cooperation sheath tube head end, make sheath tube head end can be connected with the sheath pipe more firmly, ensure to cause the danger that sheath tube head end breaks away from the sheath pipe in the intubate operation process, the sheath tube head end that obtains simultaneously is softer than sheath pipe shaft, can reduce the damage to vascular inner wall. Therefore, the utility model provides a catheter sheath is small and exquisite in external diameter not only, has compromise the stability of pliability, bending resistance and sheath tube end simultaneously moreover for this catheter sheath's sheath pipe can adapt to the blood vessel of various differences, especially some small vessels or snuff bottle district at intubate in-process safe and reliable.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments or the prior art descriptions will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive labor.

Fig. 1 is a schematic structural view of a catheter sheath according to an embodiment of the present invention;

fig. 2 is a cross-sectional view of a sheath shaft in a catheter sheath according to an embodiment of the present invention;

fig. 3 is a cross-sectional view of a sheath tip in a catheter sheath according to an embodiment of the present invention.

Wherein, in the figures, the respective reference numerals:

10. a hemostatic valve; 20. a sheath tube; 21. an inner layer; 22. an intermediate layer; 23. an outer layer; 30. a side branch; 40. a three-way valve; 50. a sheath tip end; 60. and (4) stress-removing the pipe.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

As shown in fig. 1 to 3, the embodiment of the present invention provides a catheter sheath, which comprises a hemostatic valve 10, a sheath tube 20, a side branch tube 30 and a three-way valve 40, wherein the hemostatic valve 10 is provided with a main channel and a side channel which are communicated with each other, a first end of the sheath tube 20 is communicated with the main channel, a central axis of the sheath tube 20 is coaxial with the main channel, a first end of the side branch tube 30 is communicated with the side channel, a second end of the side branch tube 30 is communicated with the three-way valve 40, and the catheter sheath is characterized in that the sheath tube 20 is formed by sequentially wrapping an inner layer 21, an intermediate layer 22 and an outer layer 23, wherein the inner layer 21 and the outer layer 23 are polymer material layers, the intermediate layer 22 is a metal wire layer, and the second end of the sheath tube.

At the second end of the sheath 20, the axial length of the outer layer 23 is smaller than that of the inner layer 21, the end surface of the sheath head end 50 is connected with the end surface of the outer layer 23, and then the inner wall of the sheath head end 50 is fixedly connected to the inner layer 21. The axial length of the intermediate layer 22 is greater than the axial length of the outer layer 23, and the axial length of the intermediate layer 22 is less than or equal to the axial length of the inner layer 21. The length of the sheath 20 is 5cm-150cm, during the process of manufacturing the second end of the sheath 20, the ends of the inner layer 21, the intermediate layer 22 and the outer layer 23 are aligned at the beginning, then a sheath (not shown) with the length of 5-50mm is placed between the inner wall of the end of the outer layer 23 and the intermediate layer 22, during the process of fixedly welding the outer layer 23 to the intermediate layer 22, due to the obstruction of the sheath, the small section of the outer layer 23 is protected from being welded on the intermediate layer 22, at this time, the small section of the outer layer 23 is protruded relative to the other outer layers 23 welded on the intermediate layer 22, and then the material of the small section of the outer layer 23 is cut off. And then the tube is formed into a tapered sheath tube head end 50 through a tip forming process and is sleeved on the inner layer 21, the end surface of the sheath tube head end 50 is aligned and contacted with the end surface of the outer layer 23, and the sheath tube head end 50 is fixedly connected on the middle layer 22. Or the end surface of the sheath head end 50 which is not formed by the tip is aligned and contacted with the end surface of the outer layer 23, the sheath head end 50 is fixedly connected to the middle layer 22, and then the tapered sheath head end 50 is formed by the tip forming process. Further, after the end surface of the sheath tip 50 is connected to the end surface of the outer layer 23, the inner wall of the sheath tip 50 is adhered or welded to the intermediate layer 22, preferably, in this embodiment, the end surface of the sheath tip 50 is welded to the end surface of the outer layer by a welding method, the inner wall of the sheath tip 50 is also welded to the intermediate layer 22 by a welding method, and the sheath tip 50 is made of a material softer than the sheath 20.

In the catheter sheath, the second end of the sheath 20 is provided with the sheath head end 50 which is tapered radially, that is, the sheath head end 50 has a tapered shape, and the end of the sheath head end 50 is smooth, so that the sheath 20 can smoothly enter the blood vessel. And, assemble through going the stress tube 60 between the first end of the sheath 20 and hemostasis valve 10, so can prevent the sheath 20 from buckling when the sheath 20 gets into the blood vessel, make the intubate operation go on smoothly. After the sheath 20 enters the blood vessel, the hemostatic valve 10 provides an entrance for a guide wire, a catheter and other devices to enter the blood vessel, and simultaneously can effectively prevent blood from flowing out, so as to prevent bleeding. By designing the side branch 30 to communicate with the hemostasis valve 10, a channel can be provided for injecting drugs into the blood vessel, monitoring the blood pressure, extracting blood samples and the like during the operation process through the side branch 30.

As shown in fig. 3, the maximum outer diameter of the sheath tip 50 is equal to the outer diameter of the outer layer 23, and the inner diameter of the sheath tip 50 is equal to the inner diameter of the inner layer 21, and at this time, an inner step is formed on the inner wall of the sheath tip 50, and the step surface of the inner step is in contact with and fixedly connected to the end surface of the inner layer 21. Or in this embodiment, the maximum outer diameter of the sheath head end 50 is smaller than the outer diameter of the outer layer 23, the joint between the sheath head end 50 and the outer layer 23 is in arc transition, the inner diameter of the sheath head end 50 is equal to the inner diameter of the inner layer 21, at this time, an inner step is formed on the inner wall of the sheath head end 50, and the step surface of the inner step is in contact with and fixedly connected with the end surface of the inner layer 21. In the sheath 20 of the catheter sheath, the inner layer 21 has a diameter of 1 to 5mm and a wall thickness of 0.005 to 0.05mm, and the outer layer 23 has a wall thickness of 0.005 to 0.2 mm.

The utility model provides a catheter sheath adopts three-layer composite structure, inlayer 21 and outer 23 all adopt macromolecular material, wherein, the sheath pipe 20 to this catheter sheath adopts the pertinence material to make, consequently, inlayer 21 adopts one of Polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polyurethane, nylon, polyether block Polyamide (PEBAX) or High Density Polyethylene (HDPE) to make, outer 23 also adopts one of Polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polyurethane, nylon, polyether block Polyamide (PEBAX) or High Density Polyethylene (HDPE) to make, inlayer 21 preferably adopts Polytetrafluoroethylene (PTFE) to make, in addition, to enhance the intravascular developability of the material, the inner layer 21 and the outer layer 23 may be one of the above materials to which a developer is added, and particularly the outer layer 23, and the outer layer 23 is preferably PEBAX + BaSO₄A material. In the process of biaxially stretching the inner layer 21 and the outer layer 23 to obtain an ultra-thin-walled tube structure having a uniform wall thickness, the material tube wall is thinned without much reduction in the axial and radial strengthsThe bending flexibility of the sheath 20 is improved, and particularly, the sheath 20 of the catheter sheath is embedded with the intermediate layer 22 between the inner layer 21 and the outer layer 23, the intermediate layer 22 is made of a metal wire, the metal wire is a round wire or a flat wire with the diameter of 0.01mm-0.05mm, and the material of the metal wire is 304 stainless steel or nickel-titanium alloy wire, so that the strength of the sheath 20 is further improved while the outer diameter of the sheath 20 is not increased. Meanwhile, in order to prevent the catheter sheath from damaging the inner wall of the blood vessel during the intubation operation, the sheath head end 50 is additionally arranged at the second end of the sheath 20, the sheath head end 50 can be made of one of Polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polyurethane, nylon, polyether block Polyamide (PEBAX) or High Density Polyethylene (HDPE), the above materials with proper hardness are selected according to the use requirements, meanwhile, the material selected for the sheath head end 50 is different from the material selected for the sheath 20, and the selected material is processed to form the sheath head end 50 which is softer than the sheath 20. In addition, in order to enhance the intravascular development of the material, a developer may be mixed and added to the material for manufacturing the sheath tip 50.

In the utility model, the inner layer 21, the outer layer 23 and the sheath tube head end 50 can be mixed with the developer to enhance the overall developing performance of the catheter sheath in the blood vessel; alternatively, it is preferable that a developer is mixed and added only to the material for manufacturing the sheath tip 50 (the developer is not mixed and added to the material for manufacturing the inner layer 21 and the outer layer 23) to show the developability of the sheath tip 50 in the blood vessel; alternatively, a developer is mixed and added only to the material for the inner layer 21; alternatively, only the material for the outer layer 23 is mixed with a developer; or the developer is mixed and added in the manufacturing materials of the inner layer 21 and the outer layer 23, and the developer is not mixed and added in the manufacturing material of the sheath head end 50; alternatively, the developer is mixed and added to the manufacturing materials of the inner layer 21 and the sheath tip 50, while the developer is not mixed and added to the manufacturing material of the outer layer 23; alternatively, the developer is mixed and added to the materials for the outer layer 23 and the sheath tip 50, while the developer is not mixed and added to the material for the inner layer 21. The above various ways of adding the developer can assist in displaying the position of the catheter sheath in the blood vessel to some extent.

Therefore, the utility model provides a catheter sheath is small and exquisite in external diameter not only, has compromise pliability, flexure resistance and the stability of sheath tube end 50 simultaneously moreover for this catheter sheath's sheath pipe 20 is at intubate in-process safe and reliable, can adapt to the blood vessel of various differences, especially the blood vessel in some small vessels or snuff bottle district.

In this embodiment, the wires of the intermediate layer 22 are helically wound around the inner layer 21, or the wires of the intermediate layer 22 are woven to form a woven mesh covering the inner layer 21. The outer layer 23 is welded and fixed to the inner layer 21. Specifically, when the intermediate layer 22 is formed by spiral winding, the density of the spiral structure is 5-100WPI (turns per inch); when the intermediate layer 22 is formed using a mesh-in-braid approach, the braid filaments have a density of 50PPI to 300PPI (number of nodes per inch). In the design and manufacture process, no matter the metal wires in the intermediate layer 22 adopt the spiral winding mode or the mesh weaving mode, the tube body with high metal wire density has better flexibility, but the bending resistance of the tube body is reduced, so that different spiral densities or weaving densities can be designed to adjust the flexibility and the bending resistance of the tube body of the sheath tube 20 so as to adapt to the trafficability requirements of different blood vessel parts.

In order to facilitate the sheath 20 to enter different blood vessels, an arc-shaped bend is provided at the body of the sheath 20 near the sheath tip 50. Moreover, different arc-shaped bending angles can be designed at the position of the sheath 20 close to the sheath head end 50 in a targeted manner corresponding to the vessels in different areas to be accessed.

In addition, the sheath 20 can also be made of a single-layer polymer material, in this case, the polymer material used for the sheath 20 is one of Polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyurethane, nylon, polyether block Polyamide (PEBAX) or High Density Polyethylene (HDPE), the extruded tube is biaxially stretched to obtain an ultrathin wall structure with uniform wall thickness, and in the stretching process, the wall of the material is thinned, but the axial and radial strength of the material is not reduced too much, so that the requirement of the sheath 20 on the strength of the tube body can be met, and the bending flexibility of the sheath 20 is improved.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A catheter sheath comprises a hemostasis valve (10), a sheath tube (20), a side branch tube (30) and a three-way valve (40), wherein the hemostasis valve (10) is provided with a main channel and a side channel which are communicated with each other, a first end of the sheath tube (20) is communicated with the main channel, the central axis of the sheath tube (20) is coaxial with the main channel, a first end of the side branch tube (30) is communicated with the side channel, and a second end of the side branch tube (30) is communicated with the three-way valve (40), and the catheter sheath is characterized in that the sheath tube (20) is formed by sequentially and externally wrapping an inner layer (21), an intermediate layer (22) and an outer layer (23) in a composite mode, wherein the inner layer (21) and the outer layer (23) are made of polymer materials, the intermediate layer (22) is made of metal wires, the second end of the sheath tube (20) is provided with a sheath tube head end (50) which is radially tapered, and the second end of the sheath tube (20, the axial length of skin (23) is less than the axial length of inlayer (21), the axial length of intermediate level (22) is greater than the axial length of skin (23), just the axial length of intermediate level (22) is less than or equal to the axial length of inlayer (21), the terminal surface of sheath pipe head end (50) with the terminal surface of skin (23) meets, the inner wall fixed connection of sheath pipe head end (50) in inlayer (21), just sheath pipe head end (50) select for use than the soft material of sheath pipe (20) is made the shaping.

2. The catheter sheath of claim 1, wherein the maximum outer diameter of the sheath tip (50) is less than the outer diameter of the outer layer (23), and the junction between the sheath tip (50) and the outer layer (23) is radiused, and wherein the inner diameter of the sheath tip (50) is equal to the inner diameter of the inner layer (21).

3. The catheter sheath of claim 1, wherein the sheath tip (50) has a maximum outer diameter equal to the outer diameter of the outer layer (23) and an inner diameter equal to the inner diameter of the inner layer (21).

4. The catheter sheath according to claim 1, wherein an end surface of the sheath tip (50) is joined to and bonded or welded to a second end surface of the outer layer (23), and an inner wall of the sheath tip (50) is bonded or welded to the inner layer (21).

5. The catheter sheath according to any one of claims 1 to 4, wherein a shaft of the sheath (20) near the sheath tip (50) is provided with an arc-shaped bend angle.

6. The sheath according to claim 5, characterized in that the wires of the intermediate layer (22) are wound helically on the inner layer (21), the inner wall of the outer layer (23) being welded to the inner layer (21).

7. The sheath according to claim 5, characterized in that the wires of the intermediate layer (22) are woven to form a woven mesh covering the inner layer (21), and the inner wall of the outer layer (23) is welded and fixed to the inner layer (21).

8. The catheter sheath according to claim 1, wherein the inner layer (21) is made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyurethane, nylon, polyether block polyamide or polyethylene, and the outer layer (23) is made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyurethane, nylon, polyether block polyamide or polyethylene.

9. The introducer sheath according to claim 8, wherein the sheath tip (50) material is made of one of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyurethane, nylon, polyether block polyamide, or polyethylene.

10. The catheter sheath according to claim 9, characterized in that the inner layer (21) is made of a material to which a developer is mixedly added; and/or, a developer is mixed and added in the manufacturing material of the outer layer (23); and/or a developer is mixed and added in the manufacturing material of the sheath tube head end (50).