Flexible tube for endoscope, endoscope-type medical device, and method for manufacturing the same

Abstract

To provide a flexible tube for an endoscope which is excellent in elasticity, can sufficiently maintain adhesion between a flexible tube base material and a polymer coating layer covering the flexible tube base material even if bending operation is repeated, and hardly causes the deterioration of the elasticity even if it is repeatedly heated, and to provide an endoscope type medical instrument equipped with the flexible tube for the endoscope, and a method for manufacturing them.SOLUTION: The flexible tube for the endoscope has a flexible tube base material made of metal, a porous layer on the flexible tube base material, a primer layer on the porous layer, and a polymer coating layer on the primer layer, and the polymer coating layer contains at least one kind of compound of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flexible tube for an endoscope, an endoscopic medical device, and a method for manufacturing the same. [Background technology]

[0002] Endoscopes are medical devices used to observe the inside of a patient's body cavities, digestive tract, esophagus, etc. Because they are inserted into the body, they are required to be free from damage to organs and cause no pain or discomfort to the patient. To meet this demand, the flexible tube that makes up the endoscope's insertion section (the structural part inserted into the body cavity) is a helical tube formed by helically winding a soft, flexible metal strip. Furthermore, the helical tube is coated with a flexible polymer, and this polymer coating layer is optionally coated with a topcoat layer to prevent irritation or damage to the inner surfaces of the esophagus, digestive tract, body cavities, etc.

[0003] This flexible tube requires high elasticity to move smoothly inside the body. By increasing the elasticity of the flexible tube, the flexible tube can easily return to a straight shape after passing through a bent section inside the body, further reducing the burden on the subject during the examination. As a technology that meets this requirement, for example, Patent Document 1 describes applying a primer to the surface of a metal core material (flexible tube base material) and then coating and molding an outer skin layer, and that this primer can be a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, or a zirconium-based coupling agent. According to Patent Document 1, this flexible tube for endoscopes has excellent elasticity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-035923 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, to improve the operability, durability, etc. of an endoscope, it is important to improve the adhesion between the flexible tube base material and the polymer coating layer that covers it. If this adhesion is insufficient, the polymer coating layer is likely to wrinkle, lift, tear, peel, etc. due to bending of the flexible tube when inserted into the body, and the polymer coating layer is likely to twist when the flexible tube is rotated while inserted. If the polymer coating layer wrinkles, lifts, tears, peels, or twists, the surface of the flexible tube inserted into the body may catch on surrounding tissue, causing pain to the subject. However, the flexible tube for an endoscope described in Patent Document 1 above cannot be said to fully meet the requirement for adhesion between the flexible tube base material and the polymer coating layer.

[0006] Furthermore, when an endoscope is in use, it is exposed to heat generated by the light source of the illumination built into the endoscope, etc. Endoscopes may also be exposed to heat of up to about 60°C during disinfection or sterilization using chemical solutions. The inventors' research has revealed that repeated use of an endoscope exposes the flexible tube to heat cycles, resulting in a decrease in elasticity. Therefore, flexible tubes for endoscopes are also required to be resistant to the effects of heat cycles (i.e., their elasticity is not easily reduced even when repeatedly heated).

[0007] An object of the present invention is to provide a flexible tube for an endoscope that has excellent elasticity, can maintain sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending operations, and is resistant to a decrease in elasticity even after repeated heating, and an endoscopic medical device equipped with this flexible tube for an endoscope. Another object of the present invention is to provide a method for manufacturing the flexible tube for an endoscope and a method for manufacturing the endoscopic medical device. [Means for solving the problem]

[0008] In view of the above-mentioned problems, the present inventors have conducted extensive research into the formation of a polymer coating layer on a flexible tube for an endoscope, and have found that the above-mentioned problems can be solved by forming a porous layer on the surface of a flexible tube substrate made of a metal material, forming a primer layer on this porous layer, and further using a specific type of polymer as a constituent material for the polymer coating layer that contacts this primer layer.The present invention was completed after further research based on these findings.

[0009] The above-mentioned problems of the present invention have been solved by the following means. <1> The flexible tube has a flexible tube substrate made of metal, a porous layer on the flexible tube substrate, a primer layer on the porous layer, and a polymer coating layer on the primer layer, A flexible tube for an endoscope, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer. <2> The porous layer contains a polymer compound, and the average pore size of the porous layer is 50 nm to 100 μm. <1> The flexible tube for an endoscope according to claim 1. <3> The primer layer contains at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent. <1> or <2> The flexible tube for an endoscope according to claim 1. <4> The primer layer contains a silane coupling agent. <1> ~ <3> 10. A flexible tube for an endoscope according to claim 9. <5> The primer layer contains an aminosilane coupling agent. <1> ~ <4> 10. A flexible tube for an endoscope according to claim 9. <6> The metal constituting the flexible tube base material is stainless steel. <1> ~ <5> 10. A flexible tube for an endoscope according to claim 9. <7> The metal constituting the flexible tube substrate has a passivation film on the surface thereof. <1> ~ <6> 10. A flexible tube for an endoscope according to claim 9. <8> the polymer coating layer has a single-layer structure or a multi-layer structure, and the layer in contact with the primer layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin; <1> ~ <7> 10. A flexible tube for an endoscope according to claim 9. <9> the polymer coating layer has a two-layer structure, and the thickness ratio of the inner layer to the outer layer of the two-layer structure changes gradually in the axial direction of the flexible tube base material; <1> ~ <8> 10. A flexible tube for an endoscope according to claim 9. <10> The thickness ratio of the inner layer to the outer layer is 95:5 to 60:40 at one end of the flexible tube for an endoscope, and 5:95 to 40:60 at the other end. <1> ~ <9> 10. A flexible tube for an endoscope according to claim 9. <11> <1> ~ <10> An endoscopic medical device having a flexible tube for an endoscope according to any one of the above. <12> The method includes providing a porous layer having an average pore size of 50 nm to 100 μm on a flexible tube substrate made of metal, providing a primer layer on the porous layer, and providing a polymer coating layer on the primer layer, A method for producing a flexible tube for an endoscope, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer. <13> <12> 10. A method for manufacturing an endoscopic medical device, comprising incorporating the flexible tube for an endoscope obtained by the method for manufacturing a flexible tube for an endoscope described in claim 1 into an insertion portion of the endoscopic medical device. <14> <1> ~ <10> 10. A method for manufacturing an endoscopic medical device, comprising incorporating the flexible tube for an endoscope according to any one of claims 1 to 9 into an insertion portion of the endoscopic medical device.

[0010] In this specification, when there are multiple substituents, linking groups, etc. (hereinafter referred to as "substituents, etc.") designated by a specific symbol, or when multiple substituents, etc. are simultaneously or alternatively specified, this means that the respective substituents, etc. may be the same or different from each other. Furthermore, even if not otherwise specified, when multiple substituents, etc. are adjacent, they may be linked to each other or condensed to form a ring. In this specification, a substituent (the same applies to a linking group) that is not specified as substituted or unsubstituted means that the group may have any substituent within the range that produces the desired effect. This also applies to compounds that are not specified as substituted or unsubstituted. In this specification, when the number of carbon atoms of a certain group is specified, this number of carbon atoms means the number of carbon atoms in the entire group. In other words, when this group has a further substituent, this number means the total number of carbon atoms including the substituent. [Effects of the Invention]

[0011] The flexible tube for endoscopes of the present invention has excellent elasticity, and can maintain sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending operations.Furthermore, the elasticity is unlikely to decrease even when exposed to the heat cycles that accompany repeated use of the endoscope. In the endoscopic medical device of the present invention, the flexible tube, which is the structural component inserted into the body, has excellent elasticity, and can sufficiently maintain adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending operations, and is less likely to lose elasticity even when exposed to heat cycles associated with repeated use. Therefore, the endoscopic medical device of the present invention has excellent durability and can further reduce the burden on the subject during use. According to the manufacturing method of the present invention for a flexible tube for an endoscope, it is possible to obtain a flexible tube for an endoscope which has excellent elasticity, can maintain sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending operations, and is less likely to lose elasticity even when exposed to the heat cycles that accompany repeated use of the endoscope. According to the manufacturing method of the endoscopic medical device of the present invention, the flexible tube constituting the device can be made to have excellent elasticity, and even after repeated bending, the adhesion between the flexible tube base material and the polymer coating layer covering it can be sufficiently maintained, and the elasticity is unlikely to decrease even when exposed to the heat cycles that accompany repeated use of the endoscope. Therefore, the manufacturing method of the endoscopic medical device of the present invention can provide an endoscopic medical device that is excellent in durability and that further reduces the burden on the subject during use. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an external view showing the configuration of an embodiment of an electronic endoscope; [Figure 2] 1 is a partial cross-sectional view showing the configuration of an embodiment of a flexible tube for an endoscope. [Figure 3] 1 is a block diagram showing the configuration of an embodiment of a manufacturing apparatus for a flexible tube for an endoscope. [Figure 4] FIG. 4 is a cross-sectional view taken along line BB in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] A preferred embodiment of an endoscopic medical device incorporating the flexible tube for endoscopes of the present invention (hereinafter, the flexible tube for endoscopes may be simply referred to as the "flexible tube") will be described using an electronic endoscope as an example. Electronic endoscopes are used as medical devices for observing the interior of the body by inserting a flexible tube into a body cavity, the digestive tract, the esophagus, etc. In the example shown in FIG. 1, an electronic endoscope 2 includes an insertion section 3 that is inserted into the body, a main body operation section 5 connected to the base end of the insertion section 3, and a universal cord 6 that is connected to a processor device and a light source device. The insertion section 3 is composed of a flexible tube 3a connected to the main body operation section 5, an angle section 3b connected thereto, and a tip section 3c connected to the tip of the flexible tube 3a and incorporating an imaging device (not shown) for capturing images inside the body. The flexible tube 3a, which accounts for the majority of the length of the insertion section 3, is flexible throughout almost its entire length, with the portion that is inserted into the body cavity, etc., having an even more flexible structure. In FIG. 1, the angle portion 3b side has a soft structure (soft), and the main body operation portion 5 side has a hard structure (hard).

[0014] [Flexible tube for endoscope] The flexible tube for an endoscope of the present invention has a flexible tube substrate made of metal, a porous layer on the flexible tube substrate, a primer layer on the porous layer, and a polymer coating layer on the primer layer, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer. That is, the flexible tube for an endoscope has a flexible tube substrate made of metal, a porous layer, a primer layer, and a polymer coating layer, in this order, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer. In FIG. 2, the porous layer and the primer layer are not shown.

[0015] The flexible tube for an endoscope of the present invention has excellent elasticity, and can maintain sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending operations, and is less likely to lose elasticity even after repeated heating. Although the reason for this is not clear, it is presumed that one factor is the anchor effect, in which the polymer coating layer penetrates into the pores of the porous layer while remaining in close contact with the primer layer.

[0016] <Flexible tube base material> The flexible tube has a flexible tube base material made of metal as its innermost layer. As shown in FIG. 2, the flexible tube substrate 14 preferably has a configuration in which a helical tube 11 is formed by helically winding a metal strip 11a on the innermost side, a tubular mesh 12 made of braided metal wires is covered on the helical tube 11, and caps 13 are fitted to both ends. The metal constituting the flexible tube substrate 14 is preferably passivated on its surface to prevent corrosion. That is, the flexible tube substrate 14 preferably has a passive film (e.g., a metal oxide film) on its outer periphery. This passivation treatment can be performed by a conventional method. For example, a passive film can be formed on the metal surface by immersing the metal in a solution containing a strong oxidizing agent such as nitric acid, heating in air (oxygen) or water (water vapor), or anodizing in a solution containing an oxidizing agent. The metal constituting the flexible tube substrate 14 is preferably stainless steel. The surface of stainless steel is usually in a state where a passivation film is formed by the combination of chromium and oxygen. However, even when stainless steel is used as the material constituting the flexible tube substrate 14, it is preferable to subject the stainless steel to the above-mentioned passivation treatment in order to more reliably form a more uniform passivation film over the entire stainless steel surface.

[0017] <Porous layer> The porous layer constituting the flexible tube of the present invention has a large number of pores (voids) in the layer. Examples of the pore shapes include spherical and ellipsoidal shapes. The pores may be independent pores or may be continuous pores formed by a series of independent pores.

[0018] The average pore size of the porous layer is not particularly limited, and from the viewpoints of elasticity, adhesion, and heat resistance, it is, for example, preferably 50 nm to 300 μm, more preferably 70 nm to 100 μm, even more preferably 150 nm to 100 μm, even more preferably 300 nm to 25 μm, even more preferably 450 nm to 25 nm, and even more preferably 450 nm to 5 μm. In this specification, the average pore size is a value determined by the method described in the Examples below.

[0019] The porosity of the porous layer is not particularly limited, and is, for example, preferably 10 to 80%, more preferably 20 to 60%, and even more preferably 30 to 50%. In this specification, the term "porosity" refers to the ratio of the volume of pores to the total volume of the porous layer including pores, and is a value determined by the method described in the Examples below.

[0020] The average thickness of the porous layer is not particularly limited and is, for example, preferably 0.01 to 1000 μm, more preferably 0.05 to 500 μm, and even more preferably 0.1 to 50 μm. In the present specification, the average layer thickness is a value determined by the method described in the Examples below.

[0021] The porous layer preferably contains a polymer compound. Examples of the polymer compound include crosslinked epoxy resins, siloxanes (polysiloxanes), vinyl resins (e.g., acrylic resins and styrene resins), and condensation resins (e.g., polyamides, polyesters, and polycarbonates), and one or more of these can be used. Among these, at least one of crosslinked epoxy resins and siloxanes is preferred, and crosslinked epoxy resins are more preferred.

[0022] The content of the polymer compound in the porous layer is not particularly limited, and is, for example, preferably 80% by mass or more, more preferably 90% by mass or more, and the porous layer may be a layer made of a polymer compound (a polymer compound layer having pores). The porous layer may contain, in addition to the polymer compound, for example, a plasticizer, a flame retardant, a reinforcing agent (e.g., an inorganic filler and a metal filler), and a stabilizer such as an antioxidant, as long as the effects of the present invention are not impaired.

[0023] As a porous layer containing a crosslinked epoxy resin (hereinafter also referred to as "epoxy resin porous layer"), for example, the porous epoxy resin membranes described in JP 2010-77358 A and JP 2013-18966 A can be used as the porous layer constituting the flexible tube of the present invention.

[0024] Examples of porous layers containing siloxane (hereinafter also referred to as "silica porous layers") that can be used as the porous layers constituting the flexible tube of the present invention include the silica-based porous film described in JP 2010-64932 A, the mesoporous silica thin films described in WO 2003 / 028097 A and WO 2003 / 075335 A, the porous silica film described in JP 2003-115486 A, the porous silica film described in JP 2005-202240 A, and the porous silica film described in JP 2003-268356 A.

[0025] <Primer layer> The primer layer constituting the flexible tube of the present invention preferably contains at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent, from the viewpoints of the elasticity of the flexible tube, the adhesion between the flexible tube substrate and the polymer coating layer, and the heat resistance of the flexible tube. The silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent used in the present invention can be a wide variety of conventional silane coupling agents applicable to the primer layer of an endoscope flexible tube. In the present invention, from the viewpoints of the resilience of the flexible tube, the adhesion between the flexible tube substrate and the polymer coating layer, and the heat resistance of the flexible tube, silane coupling agents are preferred, and aminosilane coupling agents (preferably silane coupling agents having at least one of an unsubstituted amino group and a monosubstituted amino group) are more preferred. Specific examples of silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents include the silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents used in the examples described below, but the present invention is not limited thereto. The total content of the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent in the primer layer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more. The primer layer may also be a layer made of at least one of the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent. The content of the aminosilane coupling agent in the silane coupling agent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more. The primer layer may contain components other than the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent, as long as the effects of the present invention are not impaired. Examples of such components include metal alkoxides other than the above coupling agents, binder resins, and stabilizers (e.g., surfactants and antioxidants).

[0026] In the present invention, the phrase "the primer layer contains at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent" means that at least one of the silane coupling agent, the titanium coupling agent, the zirconium coupling agent, and the aluminum coupling agent is contained in a state of reacting with the porous layer or the flexible tube substrate, and at least one of the silane coupling agent, the titanium coupling agent, the zirconium coupling agent, and the aluminum coupling agent is contained in a state of reacting with the polymer coating layer. For example, the silane coupling agent, the titanium coupling agent, the zirconium coupling agent, and the aluminum coupling agent are at least partially hydrolyzed to expose hydroxyl groups, which may react with the constituent metals of the porous layer or the flexible tube substrate or with groups on the surface of the polymer coating layer.

[0027] The thickness of the primer layer is much thinner than that of a normal adhesive layer, and is preferably, but not limited to, 1 nm to 100 nm, which differs from an adhesive layer that requires a certain thickness and softness to bond the flexible tube substrate and the polymer coating layer.

[0028] <Polymer coating layer> The flexible tube of the present invention has a polymer coating layer on the outer periphery of a flexible tube substrate on which a porous layer and a primer layer are provided in this order. In the embodiment shown in Fig. 2, the outer surface of the polymer coating layer 15 is coated with a top coat layer 16 containing fluorine or the like, which contributes to chemical resistance, etc. Although Fig. 2 shows only one layer of the spiral tube 11, it may be configured with two or more layers stacked coaxially. In the drawing, the polymer coating layer 15 and the top coat layer 16 are drawn thicker than the diameter of the flexible tube substrate 14 to clearly show the layer structure.

[0029] In the present invention, the polymer coating layer coats the outer circumferential surface of the flexible tubing substrate having the porous layer and primer layer described above. In the embodiment shown in Fig. 2, the polymer coating layer 15 has a two-layer structure formed by laminating an inner layer 17 that coats the entire circumferential surface around the axis of the flexible tubing substrate 14 and an outer layer 18 that coats the entire circumferential surface around the axis of the inner layer 17. Typically, the inner layer 17 is made of a soft polymer, and the outer layer 18 is made of a hard polymer, but the present invention is not limited to these embodiments. In the present invention, as described below, when the polymer coating layer has a multi-layer structure of two or more layers, at least the innermost layer (the layer in contact with the primer layer) contains at least one compound selected from polyamide, polyester, polyurethane, and polyolefin. Furthermore, when the polymer coating layer is a single layer in the present invention, this single polymer coating layer contains at least one compound selected from polyamide, polyester, polyurethane, and polyolefin. That is, it is preferred that the polymer coating layer in the present invention contains at least one compound selected from polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer, and at least one compound selected from polyamide, polyester, and polyurethane on the side in contact with the primer layer.

[0030] (polyamide) As the polyamide, a wide range of ordinary polyamides that can be used as polymer coating layers for flexible tubes for endoscopes can be used, including, for example, crystalline polyamides, amorphous polyamides, and polyamide elastomers. The crystalline polyamide is not particularly limited, and examples thereof include aliphatic polyamides and aromatic polyamides. Examples of aliphatic polyamides include polyε-caproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polycaproamide / polyhexamethylene adipamide copolymer (polyamide 6 / 66), polyundecamide (polyamide 11), polycaproamide / polyundecamide copolymer (polyamide 6 / 11), polydodecaamide (polyamide 11), Polyamide 12), polycaproamide / polydodecamide copolymer (polyamide 6 / 12), polyhexamethylene sebacamide (polyamide 610), polydecamethylene sebacamide (polyamide 1010), polyhexamethylene dodecamide (polyamide 612), polydecamethylene dodecamide (polyamide 1012), polyundecamethylene adipamide (polyamide 116), and mixtures or copolymers thereof.

[0031] Examples of aromatic polyamides include polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (polyamide 6T / 6I), polycaproamide / polyhexamethylene terephthalamide copolymer (polyamide 6 / 6T), polycaproamide / polyhexamethylene isophthalamide copolymer (polyamide 6 / 6I), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (polyamide 66 / 6T), polyhexamethylene Examples of such polymers include adipamide / polyhexamethylene isophthalamide copolymer (polyamide 66 / 6I), polytrimethylhexamethylene terephthalamide (polyamide TMDT), polybis(4-aminocyclohexyl)methanedodecamide (polyamide PACM12), polybis(3-methyl-4-aminocyclohexyl)methanedodecamide (nylon dimethyl PACM12), polymetaxylylene adipamide (polyamide MXD6), polydecamethylene terephthalamide (polyamide 10T), polyundecamethylene terephthalamide (polyamide 11T), and mixtures or copolymers thereof.

[0032] Examples of amorphous polyamides include polycondensates of isophthalic acid / terephthalic acid / 1,6-hexanediamine / bis(3-methyl-4-aminocyclohexyl)methane, polycondensates of terephthalic acid / 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine, polycondensates of isophthalic acid / bis(3-methyl-4-aminocyclohexyl)methane / ω-laurolactam, and polycondensates of isophthalic acid / terephthalic acid / 1,6-hexanediamine. , a polycondensation polymer of isophthalic acid / 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine, a polycondensation polymer of isophthalic acid / terephthalic acid / 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine, a polycondensation polymer of isophthalic acid / bis(3-methyl-4-aminocyclohexyl)methane / ω-laurolactam, and a polycondensation polymer of isophthalic acid / terephthalic acid / other diamine components.

[0033] Examples of polyamide elastomers include elastomers called amide-based thermoplastic elastomers, which have polyamide hard segments. Examples include multiblock copolymers in which the hard segments are polyamide and the soft segments are polyether or polyester, and multiblock copolymers in which the hard segments are polyamide and the soft segments have both ether and ester bonds. Examples of hard segments include polyamides 6, 6, 6, 10, 11, and 12. Examples of polyethers in the soft segments include polyethylene glycol, diol poly(oxytetramethylene) glycol, and poly(oxypropylene) glycol. Examples of polyesters include poly(ethylene adipate) glycol and poly(butylene-1,4-adipate) glycol.

[0034] Commercially available polyamides that can be used in the present invention include, for example, polyamide 11 (manufactured by Arkema, trade name "Rilsan BMN O"), polyamide 12 (manufactured by Daicel-Evonik, trade name "Daiamide L1940"), polyamide 1010 (manufactured by Daicel-Evonik, trade name "Vestamid Terra DS16"), polyamide 1012 (manufactured by Evonik, trade name "Vestamid Terra DD16"), amorphous polyamide (manufactured by Daicel-Evonik, trade name "Trogamid CX7323"), and polyamide elastomer (manufactured by Arkema, trade name "Pebax 4533", "Pebax 7233", and "Pebax Rnew80R53").

[0035] The polyamide may be used alone or in combination of two or more kinds.

[0036] (polyester) As the polyester, a wide range of ordinary polyesters that can be used as polymer coating layers for flexible tubes for endoscopes can be used, including, for example, thermoplastic polyesters and polyester elastomers. Examples of thermoplastic polyesters include polyester resins composed of a dicarboxylic acid component and a diol component, and polyester resins composed of a hydroxycarboxylic acid component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and cyclohexanedicarboxylic acid.

[0037] Examples of diol components include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and ethylene oxide adducts of bisphenol A and bisphenol S.

[0038] Examples of the hydroxycarboxylic acid component include ε-caprolactone, lactic acid, and 4-hydroxybenzoic acid.

[0039] The thermoplastic polyester may be a homopolymer composed of the above-mentioned dicarboxylic acid component and diol component, or a homopolymer composed of the above-mentioned hydroxycarboxylic acid component, or may be a copolymer, and may further contain a small amount of a trifunctional compound component such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, or pentaerythritol.

[0040] Examples of polyester elastomers include elastomers called ester-based thermoplastic elastomers, which have polyester hard segments, multiblock copolymers in which the hard segments are crystalline polyester and the soft segments are polyether or polyester, and multiblock copolymers in which the hard segments are crystalline polyester and the soft segments have both ether and ester bond bonding modes. Examples of the hard segment include polybutylene terephthalate and polyethylene terephthalate. Examples of the soft segment include polyalkylene glycols such as polytetramethylene glycol and polypropylene glycol, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, and polyesters such as polycaprolactone. As the polyester elastomer, for example, a block copolymer consisting of a high-melting polyester segment (hard segment) and a low-melting polymer segment (soft segment) having a molecular weight of 400 to 6,000, as described in JP-A No. 11-92636, can be used.

[0041] Examples of commercially available polyesters that can be used in the present invention include polyester elastomers (manufactured by Toyobo Co., Ltd. under the trade names "Pelprene P-40B," "Pelprene P-70B," and "Pelprene S-3001," and manufactured by Mitsubishi Chemical Corporation under the trade name "Primalloy B1942") and polybutylene terephthalate (manufactured by Mitsubishi Engineering Plastics Corporation under the trade name "Novaduran 5505S").

[0042] The polyester may be used alone or in combination of two or more kinds.

[0043] (Polyurethane) As the polyurethane, a wide variety of ordinary polyurethanes applicable to polymer coating layers of flexible tubes for endoscopes can be used. For example, carbonate-based, ether-based, or ester-based polyurethanes, or mixtures thereof, can be used. Polyurethane elastomers are also preferred. Examples of polyurethane elastomers include block polymers called urethane-based thermoplastic elastomers, in which the hard segment is polyurethane and the soft segment has an ether, ester, or carbonate bond, or a mixture of these bonds, and can be prepared appropriately depending on the purpose. For example, examples include block polymers containing a hard segment composed of a low-molecular-weight glycol component and a diisocyanate component, and a soft segment composed of a high-molecular-weight (long-chain) diol component and a diisocyanate component. Examples of the polymeric (long-chain) diol component include polyether diols, polyester diols, and lactone-based polyester diols. Examples include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene adipate-co-1,4-butylene adipate), polycaprolactone-based diols, poly(1,6-hexylene carbonate), and poly(1,6-hexylene adipate-co-neopentylene adipate). The number-average molecular weight of the polymeric (long-chain) diol is preferably 500 to 10,000. As the low molecular weight glycol component, short chain diols such as ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A can be used. The number average molecular weight of the short chain diol is preferably 48-500. Examples of the diisocyanate component include diphenylmethane diisocyanate, hexamethylene diisocyanate, tolidine diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate.

[0044] For the polyurethane elastomer according to the above embodiment, the disclosure of JP-A-2005-015643 can be referred to, for example.

[0045] Commercially available polyurethanes that can be used in the present invention include, for example, PANDEX T-2185 and T-2983N (manufactured by DIC Corporation), Miractoran (manufactured by Nippon Miractoran Co., Ltd.), Pandex (manufactured by DIC Corporation), Elastollan (manufactured by BASF Japan Ltd.), Lezamin (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Pellethene (manufactured by Dow Chemical Japan), Iron Rubber (manufactured by NOK Corporation), and Mobilon (manufactured by Nisshinbo Chemical Inc.). Examples of suitable polyurethanes include Isoplast (manufactured by Lubrizol Corporation), Tecoflex (manufactured by Lubrizol Corporation), Superflex 830, 460, 870, 420, or 420NS (polyurethanes manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Hydran AP-40F, WLS-202, or HW-140SF (polyurethanes manufactured by DIC Corporation), Olester UD500 or UD350 (polyurethanes manufactured by Mitsui Chemicals, Inc.), and Takelac W-615, W-6010, W-6020, W-6061, W-405, W-5030, W-5661, W-512A-6, W-635, or WPB-6601 (manufactured by DIC Corporation).

[0046] The polyurethane may be used alone or in combination of two or more kinds.

[0047] (Polyolefin) As the polyolefin, a wide range of ordinary polyolefins that can be used as polymer coating layers for flexible tubes for endoscopes can be used, including, for example, polyolefin resins and olefin-based elastomers.

[0048] Examples of polyolefin resins or rubbers include homopolymers or copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene. Also included are copolymers of α-olefins and non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene. Other examples include ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, propylene-α-olefin copolymer rubber, and butene-α-olefin copolymer rubber. Furthermore, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-(meth)acrylic acid copolymer, ethylene-propylene-(meth)acrylic acid copolymer, ethylene-propylene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, ethylene-butene-maleic anhydride copolymer, ethylene-butene-(meth)acrylic acid copolymer, ethylene-butene-maleic anhydride-(meth)acrylic acid copolymer, propylene-butene-maleic anhydride copolymer, propylene-butene-(meth)acrylic acid copolymer, propylene-butene-maleic anhydride-(meth)acrylic acid copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl chloride copolymer, and ethylene-(meth)acrylic acid copolymer can also be used.

[0049] Examples of polyolefins in olefin-based elastomers include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-α-olefin copolymers, propylene-1-butene copolymers, propylene-α-olefin copolymers, 1-butene-α-olefin copolymers, propylene-1-butene-ethylene copolymers, propylene-α-olefin-ethylene copolymers, propylene-α-olefin-1-butene copolymers, 1-butene-α-olefin-ethylene copolymers, and polypropylene. Examples of the rubber component in the olefin-based elastomer include propylene rubber (PP), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polyisoprene, polybutadiene, polychloroprene, and isobutylene-isoprene copolymer. The olefin-based elastomer may contain one kind of polyolefin and one kind of rubber component, or two or more kinds of them.

[0050] Commercially available polyolefins that can be used in the present invention include, for example, "Sarlink 3145D" (trade name, manufactured by Toyobo Co., Ltd.) and Xelas MC707 (trade name, manufactured by Mitsubishi Chemical Corporation).

[0051] The polyolefin may be used alone or in combination of two or more kinds.

[0052] The total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the polymer coating layer when the polymer coating layer is a single layer, and the total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the innermost layer when the polymer coating layer is a multilayer, are both preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. Furthermore, when the polymer coating layer is a single layer, the polymer coating layer may be a layer made of at least one compound selected from polyamide, polyester, polyurethane, and polyolefin, and when the polymer coating layer is a multilayer, the innermost layer may be a layer made of at least one compound selected from polyamide, polyester, polyurethane, and polyolefin. When the polymer coating layer is a single layer, or when the polymer coating layer is a multi-layer, the innermost layer contains a polymer other than a polymer selected from polyamide, polyester, polyurethane, and polyolefin, there are no particular restrictions on the polymer as long as it does not impair the effects of the present invention. The polymer coating layer may contain various commonly used additives as appropriate, provided that the effects of the present invention are not impaired. Examples of such additives include heat stabilizers, inorganic fillers, impact modifiers, plasticizers, lubricants, metal soaps, light resistance aids, and colorants. The content of the additives in the polymer coating layer may also be adjusted as appropriate. Such additives may be derived from the polymer material used, or may be added separately from the polymer.

[0053] In the case where the polymer coating layer is a multi-layer structure, the layers other than the innermost layer preferably contain at least one compound selected from polyamide, polyester, polyurethane, and polyolefin. These polymers can be appropriately combined to form a layer having desired physical properties. The total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the layers other than the innermost layer is the same as the total content in the innermost layer.

[0054] The above-mentioned polymers that can be used in the polymer coating layer of the present invention preferably have a molecular weight of 10,000 to 1,000,000, more preferably 20,000 to 500,000, and particularly preferably 30,000 to 300,000. In the present invention, unless otherwise specified, the molecular weight of the polymer constituting the polymer coating layer means the weight average molecular weight, which can be measured as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC).

[0055] As shown in Fig. 2, in the present invention, the polymer coating layer 15 is preferably formed with a substantially uniform thickness in the longitudinal direction (axial direction) of the flexible tube substrate 14. The thickness of the polymer coating layer 15 is, for example, 0.2 mm to 1.0 mm. The outer diameter D of the flexible tube 3a is set appropriately depending on the purpose, for example, 11 to 14 mm. In Fig. 2, the thicknesses of the inner layer 17 and the outer layer 18 are formed so that the ratio of the thickness of each layer 17, 18 to the total thickness of the polymer coating layer 15 varies in the axial direction of the flexible tube substrate 14. Specifically, at the one end 14a side (tip side) of the flexible tube substrate 14 attached to the angle portion 3b, the thickness of the inner layer 17 is greater than the thickness of the outer layer 18, relative to the total thickness of the polymer coating layer 15. The thickness of the inner layer 17 gradually decreases from one end 14a toward the other end 14b (base end side) attached to the main body operating unit 5, and at the other end 14b side, the thickness of the outer layer 18 is greater than the thickness of the inner layer 17.

[0056] In FIG. 2, the thickness ratio of the inner layer 17 is greatest at one end 14a, and the thickness ratio of the outer layer 18 is greatest at the other end 14b. The ratio of the thickness of the inner layer 17 to the thickness of the outer layer 18 can be, for example, 9:1 at one end 14a and 1:9 at the other end 14b. The thicknesses of the inner layer 17 and the outer layer 18 are changed so that the thickness ratio is reversed from one end 14a to the other end 14b. This creates a difference in hardness between the one end 14a and the other end 14b of the flexible tube 3a, allowing the flexibility to change in the axial direction so that the one end 14a is softer and the other end 14b is harder. The thickness ratio of the inner layer to the outer layer at one end is preferably 95:5 to 60:40 (inner layer:outer layer), and the thickness ratio at the other end is preferably 5:95 to 40:60 (inner layer:outer layer). By setting the thickness ratio between the inner layer 17 and the outer layer 18 within the range of 95:5 to 5:95, it is possible to precisely control the amount of polymer extruded from the thinner layer.

[0057] The difference in 100% modulus, an index of hardness after molding, between the soft polymer and hard polymer used in the inner layer 17 and the outer layer 18 is preferably 1 MPa or more, more preferably 3 MPa or more. The difference in melt viscosity at molding temperatures of 150°C to 300°C, an index of the fluidity of the polymer in a molten state, is preferably 2500 Pa·s or less. This ensures that the polymer coating layer 15 consisting of the inner layer 17 and the outer layer 18 has both good molding precision and the necessary hardness difference between the distal and proximal ends.

[0058] <Top coat layer> In the flexible tube of the present invention, a top coat layer 16 is disposed on the outer periphery of the polymer coating layer 15 as needed. The material for the top coat layer is not particularly limited, and examples thereof include urethane paint, acrylic paint, fluorine paint, silicone paint, epoxy paint, and polyester paint. The main purpose of using a top coat layer is to protect the surface of the flexible tube, to give it a glossy finish, slipperiness, and chemical resistance, so it is preferable that the top coat layer has a high elastic modulus, a smooth surface, and excellent chemical resistance.

[0059] [Manufacturing method of flexible tube] <Porous layer formation> In the manufacturing of the flexible tube of the present invention, a porous layer is formed on a flexible tube substrate. The formation of the porous layer can be carried out with reference to, for example, JP 2010-77358 A, JP 2013-18966 A, JP 2010-64932 A, WO 2003 / 028097 A, WO 2003 / 075335 A, JP 2003-115486 A, JP 2005-202240 A, JP 2003-268356 A, and WO 2008 / 093731 A. The method for producing a flexible tube of the present invention preferably includes forming a porous layer having an average pore size of 50 nm to 100 μm. As described later, the average pore size of the porous layer can be controlled by the raw material of the porous layer, etc. Hereinafter, the methods for forming the epoxy resin porous layer and the silica porous layer will be specifically described. Note that the following description is an example, and the formation of the porous layer in the present invention is not limited to these forms.

[0060] (Method for forming a silica porous layer) The silica porous layer can be formed on (the outer periphery of) the flexible tube substrate through the following steps (i) and (ii). (i) A silica composition is prepared by subjecting an alkoxysilane compound to a dehydration condensation reaction in the presence of a pore-forming agent. (ii) After applying the silica composition to the flexible tube substrate, the silica composition is dried (or heated) to form a coating film, and then further heated at a high temperature to decompose and remove the pore-forming agent, thereby forming pores in the coating film.

[0061] In the above step (i), the alkoxysilane compound is subjected to a dehydration condensation reaction in a mixed liquid containing the alkoxysilane compound, a pore-forming agent, and a solvent to obtain a silica composition. For example, an alkoxysilane compound, a pore-forming agent, and a solvent containing water are mixed, and if necessary, a catalyst described below is added. While mixing, the alkoxysilane compound is subjected to a dehydration condensation reaction in the presence of the pore-forming agent, and if necessary, the mixture is concentrated or diluted with a solvent to obtain a silica composition. The reaction conditions (reaction temperature, reaction time) for the dehydration condensation reaction may be those of a conventional method.

[0062] The alkoxysilane compound is not particularly limited, and tetraalkoxysilane compounds, trialkoxysilane compounds, dialkoxysilane compounds, etc. can be used appropriately. The tetraalkoxysilane is not particularly limited, and examples thereof include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Examples of trialkoxysilane compounds include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. Examples of the dialkoxysilane compound include dimethyldimethoxysilane and dimethyldiethoxysilane.

[0063] The total silica content in the silica composition (the content of the dehydration condensation reaction product) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, while the total content of the silane compounds is preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 20% by mass or less.

[0064] The pore-forming agent can be one that is encapsulated in silica and can be decomposed and removed by heating. Examples of the pore-forming agent include surfactants. Examples of surfactants that can be used include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Nonionic surfactants are preferred, and nonionic surfactants with a polymer structure are more preferred. When the surfactant is a polymer, its number average molecular weight is, for example, 300 to 5,000.

[0065] The content of the surfactant in the silica composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 1.2% by mass or more, and even more preferably 1.4% by mass or more, while the content is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

[0066] The solvent is preferably water or a combination of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include alcohol compounds such as monohydric alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, t-butanol, and 1-pentanol, dihydric alcohols having 1 to 4 carbon atoms, and polyhydric alcohols, such as glycerin and pentaerythritol; ethers or esters of the above alcohol compounds, such as methyl acetate, ethyl acetate, isobutyl acetate, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, 2-ethoxyethanol, propylene glycol monomethyl ether, and propylene glycol methyl ether acetate; acetone, methyl ethyl ketone, etc. ketone compounds such as those listed above; amide compounds such as formamide, N-methylformamide, N-ethylformamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylacetamide, N-ethylacetamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidone, N-formylmorpholine, N-acetylmorpholine, N-formylpiperidine, N-acetylpiperidine, N-formylpyrrolidine, N-acetylpyrrolidine, N,N'-diformylpiperazine, N,N'-diformylpiperazine, and N,N'-diacetylpiperazine; lactone compounds such as γ-butyrolactone; ureas such as tetramethylurea and N,N'-dimethylimidazolidine; dimethyl sulfoxide, etc. Among these, alcohols are preferred, and monohydric alcohols are more preferred, in order to perform hydrolysis under conditions that are more stable for the alkoxysilane compound contained therein.

[0067] The silica composition usually contains a catalyst, and any substance that accelerates the hydrolysis and dehydration condensation reaction of the alkoxysilane compound can be used as the catalyst. Examples of such acids include hydrofluoric acid, phosphoric acid, boric acid, hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, maleic acid, methylmalonic acid, stearic acid, linoleic acid, benzoic acid, phthalic acid, citric acid, and succinic acid; amine compounds such as ammonia, butylamine, dibutylamine, and triethylamine; bases such as pyridine; and Lewis acids such as aluminum acetylacetone complexes. Other examples of catalysts include metal chelate compounds, whose metal species include titanium, aluminum, zirconium, tin, and antimony.

[0068] The silica composition may contain components other than the above-mentioned alkoxysilane compound, organic solvent, surfactant, water, and catalyst, as long as the effects of the present invention are not impaired.

[0069] In the step (ii), a flexible tube substrate is immersed in the silica composition obtained in the step (i), and then the flexible tube substrate is taken out and dried to form a coating film. Subsequently, the surfactant is decomposed and removed at a high temperature (e.g., 250°C or higher), thereby obtaining a flexible tube substrate having a silica porous layer.

[0070] The average pore size and porosity of the silica porous layer can be controlled by the types of raw materials, the blending ratio of the raw materials, and reaction conditions (for example, drying or heating temperature and heating time).

[0071] (Method for forming an epoxy resin porous layer) The epoxy resin porous layer can be formed on (the outer periphery of) the flexible tube substrate through the following steps (1) to (3). (1) A mixed liquid containing an epoxy resin, a pore-forming agent, a solvent, and a curing agent for the epoxy resin is prepared. (2) The mixed solution is applied to a flexible tube substrate, dried, and then heated to react the epoxy resin with the curing agent. (3) Removing the pore former from the cured epoxy resin.

[0072] In the above step (1), a mixed solution containing an epoxy resin, a curing agent, and a pore-forming agent is prepared. This mixing is carried out at room temperature (e.g., 25 to 30°C) or a lower temperature for about 5 to 30 minutes to obtain a uniform mixture.

[0073] As the epoxy resin, aromatic epoxy resins and non-aromatic epoxy resins can be used. Examples of aromatic epoxy resins include polyphenyl-based epoxy resins, epoxy resins containing a fluorene ring, epoxy resins containing triglycidyl isocyanurate, and epoxy resins containing a heteroaromatic ring (for example, a triazine ring). Examples of polyphenyl-based epoxy resins include bisphenol A-type epoxy resins, brominated bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, stilbene-type epoxy resins, biphenyl-type epoxy resins, bisphenol A novolac-type epoxy resins, cresol novolac-type epoxy resins, diaminodiphenylmethane-type epoxy resins, and tetrakis(hydroxyphenyl)ethane-based epoxy resins. Examples of non-aromatic epoxy resins include aliphatic glycidyl ether type epoxy resins, aliphatic glycidyl ester type epoxy resins, alicyclic glycidyl ether type epoxy resins, alicyclic glycidyl amine type epoxy resins, and alicyclic glycidyl ester type epoxy resins. The above epoxy resins may be used alone or in combination of two or more.

[0074] As the curing agent, conventional curing agents used for curing epoxy resins, such as amine compounds, acid anhydrides, and imidazole compounds, can be used. Examples of amine compounds include 1,6-diaminohexane, 1,4-diaminobutane, and 1,8-diaminooctane. The above curing agents can be used alone or in combination of two or more.

[0075] The ratio of the content of the curing agent to the epoxy resin in the mixed liquid in step (1) is, for example, preferably 0.1 to 1.5 equivalents of the curing agent per 1 equivalent of the epoxy group of the epoxy resin, more preferably 0.2 to 1.0.

[0076] Specific examples of the pore-forming agent include cellosolve compounds such as methyl cellosolve and ethyl cellosolve, ester compounds such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, glycol compounds such as polyethylene glycol and polypropylene glycol, and ether compounds such as polyoxyethylene monomethyl ether and polyoxyethylene dimethyl ether. The above pore-forming agents may be used alone or in combination of two or more.

[0077] The content of the pore-forming agent in the total content of the epoxy resin, curing agent, and pore-forming agent can be, for example, 10 to 80 mass %.

[0078] The solvent is a solvent capable of dissolving components such as the epoxy resin, the curing agent, the pore-forming agent, etc. For example, organic solvents such as methyl ethyl ketone, acetone, toluene, cyclohexanone, and MIBK (methyl isobutyl ketone) are preferred.

[0079] In the step (2), the mixed solution obtained in the step (1) is applied to the surface of the flexible tube substrate by, for example, immersing the flexible tube substrate in the mixed solution, and then the substrate is dried to remove the solvent, and heated, for example, at about 60 to 120°C for 30 minutes to 4 hours to form an epoxy resin layer on the flexible tube substrate.

[0080] In the above step (3), the flexible tube substrate is immersed in a solvent that dissolves the pore-forming agent but not the epoxy resin, and if necessary, ultrasonic treatment is performed to remove the pore-forming agent from the epoxy resin layer. Examples of the solvent that dissolves the pore-forming agent but not the epoxy resin include water, or a mixture of water and at least one of DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), and THF (tetrahydrofuran).

[0081] The average pore size and porosity of the epoxy resin porous layer can be controlled by the types of raw materials, the blending ratio of the raw materials, and reaction conditions (for example, the heating temperature and heating time during reaction-induced phase separation).

[0082] In the present invention, as long as the effects of the present invention are not impaired, there may be a portion of the outer periphery of the flexible tube substrate that is not covered by the porous layer (i.e., there may be voids in part of the porous layer).

[0083] Before forming the porous layer, the flexible tube substrate is preferably degreased and washed with an acid solution, an alkaline solution, an aqueous surfactant solution, an organic solvent, etc. After the above washing, it is also preferable to further wash the substrate with water or warm water so that the amount of acid, alkali, surfactant, etc. on the substrate surface is reduced.

[0084] <Formation of primer layer> In the production of the flexible tube substrate of the present invention, after the porous layer is formed, a primer layer is formed on the porous layer. The primer layer can be formed by preparing a coating solution by dissolving at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent in a solvent, applying or spraying this coating solution to the outer periphery of the flexible tube substrate, or immersing the flexible tube substrate in this coating solution to form a coating film on at least the outer periphery of the flexible tube substrate, and then drying the coating film by a conventional method (for example, drying at a high temperature of about 100°C). The solvent used in the coating solution may be an alcohol solvent such as methanol or ethanol, a ketone solvent such as acetone or methyl ethyl ketone, an ester solvent such as ethyl acetate, a hydrocarbon solvent such as toluene, or a mixture thereof. Furthermore, it is preferable to mix water or an acid catalyst such as acetic acid with these solvents to promote hydrolysis of the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent. The coating solution may be acidic (e.g., pH 1 to 4 at 25°C) or alkaline (e.g., pH 9 to 11 at 25°C). The contents of the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent in the coating liquid are not particularly limited, and can be, for example, 0.01 to 2 mass% in total, preferably 0.05 mass% or more and less than 1.5 mass%, and more preferably 0.1 mass% or more and less than 1.0 mass%. The coating liquid may contain at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent, a solvent, a pH adjuster, as well as a surfactant, a catalyst, etc. More preferably, the coating liquid is composed of at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent, and a solvent. In the present invention, there may be a part of the porous layer that is not covered with the primer layer (i.e., there may be voids in part of the primer layer) as long as the effect of the present invention is not impaired.

[0085] <Formation of polymer coating layer> The formation of the polymer coating layer will be described using an example in which the polymer coating layer has a two-layer structure. A flexible tube having a two-layer structure in which the polymer coating layer consists of an inner layer and an outer layer can be obtained, for example, by melt-kneading a first polymer material (a polymer material containing at least one compound of polyamide, polyester, polyurethane, and polyolefin) that constitutes the inner layer and a second polymer material that constitutes the outer layer around a flexible tube base material on which the primer layer is formed, extrusion-molding the material, and coating the flexible tube base material. Incidentally, embodiments in which the polymer coating layer is one layer or three or more layers can also be obtained by appropriately changing the layer structure with reference to the following method.

[0086] An example of a method for forming a polymer coating layer on a flexible tube 3a (FIGS. 1 and 2) will be described with reference to FIGS. 3 and 4. In this embodiment, a continuous molding machine is used to form the polymer coating layer 15. The continuous molding machine 20 preferably includes well-known extrusion sections 21 and 22, each including a hopper and screws 21a and 22a, a head section 23 for forming the polymer coating layer 15 on the outer circumferential surface of the flexible tube substrate 14, a cooling section 24, a conveying section 25 (a supply drum 28 and a take-up drum 29) for conveying the connected flexible tube substrate 31 to the head section 23, and a control section 26 for controlling these sections. The head section 23 preferably includes a nipple 32, a die 33, and a support 34 for fixedly supporting these sections. An example of the configuration of such an apparatus is shown in FIGS. 3 to 5 of JP 2011-72391 A.

[0087] The interior of the die 33 is preferably heated to a predetermined molding temperature. The molding temperature is preferably set in the range of 150°C to 300°C. The temperatures of the first polymer material 39 and the second polymer material 40 can be increased by adjusting the heating temperature of the heating section within the device. In addition, the higher the rotation speed of the screws 21a and 22a, the higher the temperatures of the first polymer material 39 and the second polymer material 40 can be, thereby increasing their fluidity. At this time, the conveying speed of the connected flexible tube substrate 31 is kept constant, and the molding thicknesses of the inner layer 17 and the outer layer 18 can be adjusted by changing the discharge rates of the molten first polymer material 39 and the second polymer material 40.

[0088] The process of molding the polymer coating layer 15 on the connected flexible tubing substrate 31 using the continuous molding machine 20 will be described below. When the continuous molding machine 20 performs the molding process, a first polymer material 39 and a second polymer material 40 in a molten state are extruded from the extrusion units 21 and 22 toward the head unit 23. At the same time, the conveying unit 25 operates to convey the connected flexible tubing substrate 31 to the head unit 23. At this time, the extrusion units 21 and 22 are constantly extruding the first polymer material 39 and the second polymer material 40 to supply them to the head unit 23. The first polymer material 39 and the second polymer material 40 extruded from the extrusion units 21 and 22 to the gates 35 and 36 meet after passing through the edges, and are supplied in an overlapping state to the molding passage 37 through the polymer passage 38. This forms a two-layer molded polymer coating layer 15, in which the inner layer 17 using the first polymer material 39 and the outer layer 18 using the second polymer material 40 overlap each other.

[0089] The connected flexible tube substrate 31 is formed by connecting multiple flexible tube substrates 14 (each of which has a porous layer and a primer layer formed on its outer periphery), and polymer coating layers 15 are continuously formed on the multiple flexible tube substrates 14 while they are transported through the molding passage 37. When the polymer coating layer 15 is formed from one end 14a (tip end) of one flexible tube substrate to the other end 14b (base end), the thickness of the inner layer 17 is made thick immediately after the extrusion units 21 and 22 begin to extrude the polymer. Then, the thickness of the outer layer 18 is gradually increased in the intermediate portion toward the other end 14b. In this way, it is preferable to control the amount of polymer extrusion so that the thickness of the polymer coating layer 15 has the above-mentioned gradient.

[0090] Because the joint member 30 is a connecting portion between the two flexible tube substrates 14, the control unit 26 is used to switch the discharge rates of the extrusion units 21 and 22. Specifically, the control unit 26 preferably switches the discharge rates of the extrusion units 21 and 22 so that the thickness ratio at the other end 14b (base end) of one flexible tube substrate 14 matches the thickness ratio at the one end 14a (tip end) of the next flexible tube substrate 14. When forming the polymer coating layer 15 from the one end 14a to the other end 14b of the next flexible tube substrate 14, it is preferable to similarly control the extrusion units 21 and 22 so that the thickness of the outer layer gradually increases from the one end to the other end.

[0091] The connected flexible tube substrate 31, on which the polymer coating layer 15 has been formed up to its rearmost end, is removed from the continuous molding machine 20, and then the joint members 30 are removed from the flexible tube substrates 14, and the flexible tube substrates 14 are separated. Next, a top coat layer 16 is coated on top of the polymer coating layer 15 of each separated flexible tube substrate 14, thereby completing the flexible tube 3a. The completed flexible tube 3a is transported to the electronic endoscope assembly process.

[0092] In the present invention, when the polymer coating layer is a multi-layered layer, a functional layer may be interposed between each of the layers constituting the multi-layered layer. The above description, with reference to the drawings, has been given taking as an example an electronic endoscope that uses an imaging device to observe images of the condition of a subject, but the present invention is not limited to this and can also be applied to an endoscope that uses an optical image guide to observe the condition of a subject.

[0093] The flexible tube of the present invention can be widely applied to endoscopic medical devices. For example, it can be applied to endoscopes equipped with clips or wires at the tip, or to instruments equipped with baskets or brushes. Note that endoscopic medical devices broadly include not only medical devices that have the above-mentioned endoscope as their basic structure, but also medical or diagnostic devices that have flexible insertion portions and are inserted into the body for use, such as remote-controlled medical devices. The endoscopic medical device of the present invention has the flexible endoscope tube of the present invention incorporated into its insertion section. That is, the method for producing the endoscopic medical device of the present invention includes incorporating the flexible endoscope tube of the present invention into the insertion section of the endoscopic medical device. [Example]

[0094] The present invention will be described in more detail below through examples, but the present invention should not be construed as being limited thereto.

[0095] [Fabrication of flexible tubes for endoscopes] A flexible tube was fabricated with the structure shown in Figure 2. The polymer coating layer had a single-layer structure or a two-layer structure as shown in Table 2 below.

[0096] <Flexible tube base material> A flexible tube substrate was prepared by forming a spiral tube 11 using a stainless steel (SUS304) metal strip 11a and covering this spiral tube 11 with a tubular mesh body 12 woven with SUS304 fibers. This flexible tube substrate was 80 cm long and 12 mm in diameter. A passivation layer was formed on the surface of this stainless steel flexible tube due to an annealing treatment (heat treatment) performed during the formation of the spiral tube and the tubular mesh body. This flexible tube substrate was degreased with acetone and then immersed in a 1N aqueous solution of sodium hydroxide at 50°C for 3 minutes to clean it. It was then rinsed three times with distilled water and dried in an oven heated to 100°C for 10 minutes to prepare a flexible tube substrate.

[0097] <Formation of epoxy resin porous layer (L-1)> In a stainless steel container, 10.0 g of bisphenol A epoxy resin ("jER828" (trade name) manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 184-194 g / eq.), 4.0 g of polyethylene glycol ("Sannyx PEG-400" (trade name) manufactured by Sanyo Chemical Industries, Ltd.), and 1950.0 g of methyl ethyl ketone were mixed to prepare an epoxy resin / polyethylene glycol methyl ethyl ketone solution. 15.0 g of 1,6-diaminohexane was added to this solution, and the mixture was stirred at room temperature for 15 minutes using a Three-One motor to obtain epoxy resin solution (D). The washed flexible tube substrate was immersed in epoxy resin solution (D) for 5 minutes, then removed and air-dried at 40°C for 30 minutes to volatilize the methyl ketyl ketone. The flexible tube substrate was heated in an oven at 100°C for 3 hours to form an epoxy resin layer on the outer periphery of the flexible tube substrate. Next, the flexible tube substrate with the epoxy resin layer formed thereon was ultrasonically cleaned in a 1 / 1 (v / v) mixture of distilled water and dimethylformamide for 10 minutes, then ultrasonically cleaned in distilled water alone for 10 minutes, and then immersed in distilled water for 12 hours to remove the polyethylene glycol contained therein. Thereafter, drying was carried out at 80° C. for 2 hours to form an epoxy resin porous layer (L-1) on the outer periphery of the flexible tube substrate.

[0098] <Formation of epoxy resin porous layers (L-2) to (L-9)> Epoxy resin porous layers (L-2) to (L-9) were formed on the outer periphery of a flexible tubing substrate in the same manner as for the epoxy resin porous layer (L-1), except that the components shown in Table 1 below were used. That is, flexible tubing substrates each having epoxy resin porous layers (L-2) to (L-9) on the outer periphery were obtained.

[0099] <Formation of silica porous layers (L-10) to (L-13)> In a stainless steel container, 1,000 g of hydrolyzed silicate ("HAS-1" (trade name) manufactured by Nippon Colcoat Co., Ltd., solid content 21% by mass, 2-propanol / ethanol / methanol solvent), 45 g of polyethylene glycol ("Sannyx PEG-400" (trade name) manufactured by Sanyo Chemical Industries, Ltd.), and 955 g of isopropyl alcohol were mixed to obtain silica composition (a). The washed flexible tube substrate was immersed in silica composition (a) for 5 minutes, then removed and air-dried for 30 minutes at 40°C to volatilize the solvent. The flexible tube substrate was then heated in an oven at 100°C for 10 minutes to form a silica layer on the outer periphery of the flexible tube substrate. Next, the flexible tube substrate with the silica layer formed thereon was ultrasonically cleaned in a 1 / 1 (v / v) mixture of distilled water and dimethylformamide for 10 minutes, then ultrasonically cleaned in distilled water alone for 10 minutes, and then immersed in distilled water for 12 hours to remove the polyethylene glycol contained therein. Thereafter, drying was carried out at 80° C. for 2 hours to form a silica porous layer (L-10) on the outer periphery of the flexible tube substrate.

[0100] <Formation of silica porous layers (L-11) to (L-13)> Silica porous layers (L-11) to (L-13) were formed on the outer periphery of a flexible tubular substrate in the same manner as for the silica porous layer (L-10), except that the components shown in Table 2 below were used. That is, flexible tubular substrates each having silica porous layers (L-11) to (L-13) on the outer periphery were obtained.

[0101] <Formation of epoxy non-porous layer (R-1)> An epoxy resin layer (R-1) having no pores was formed in the same manner as in the formation of the epoxy porous layer (L-1), except that a nonionic surfactant was not used.

[0102] <Formation of Silica Non-Porous Layer (R-2)> A silica layer (R-2) having no pores was formed in the same manner as in the formation of the silica porous layer (L-10), except that polyethylene glycol was not used.

[0103] The average pore size, porosity, and average layer thickness of the porous layer were measured and calculated as follows. The measurement results are shown in Table 1 below. <Average pore diameter, porosity> The flexible tube was placed in an oven set at 150°C for 4 hours, and then left to stand in a desiccator until it reached room temperature, and then used for measurement. Measurements were performed by the mercury intrusion method using a porosimeter (Micromeritics' "Poresizer 9320" (product number)). The initial pressure was 20 kPa, the pore size measured was 3 nm to 400 μm, the measurement mode was pressure increase (intrusion), the measurement cell volume was approximately 6 cm3, the mercury contact angle was 130°, and the mercury surface tension was 484 dyn / cm.

[0104] <Average layer thickness> The flexible tube substrate thus prepared was cut at five random locations, and the cross sections of the porous layers were observed at 50,000x magnification using a scanning electron microscope (S-5500 (trade name), manufactured by Hitachi High-Technologies Corporation). The thickness of the porous layer formed on the outer periphery was measured at one point on each cross section. The number average value was calculated from the five values ​​obtained.

[0105] [Table 1]

[0106] [Table 2]

[0107] <Notes for Tables 1 and 2> The unit of usage is "g." jER828: Bisphenol A epoxy resin ("jER828" (trade name) manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 184-194g / eq.) HAS-1: Trade name, manufactured by Nippon Colcoat Co., Ltd., solid content 21% by mass, 2-propanol / ethanol / methanol solvent PEG: Polyethylene glycol (Sanyo Chemical Industries, Ltd. "Sannyx PEG-400" (trade name)) PP-400: Polypropylene glycol ("Sannyx PP-400" (trade name) manufactured by Sanyo Chemical Industries, Ltd.) PP-1000: Polypropylene glycol (Sanyo Chemical Industries, Ltd. "Sannyx PP-1000" (product name)) PP-3000: Polypropylene glycol (Sanyo Chemical "Sannyx PP-3000" (product name)) DAH: 1,6-diaminohexane MEK: Methyl ethyl ketone IPA: Isopropyl alcohol

[0108] <Formation of primer layer> 150 g of ethanol, 350 g of water, and 1.0 g of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (S-1, trade name: KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to prepare a coating liquid for forming a primer layer. A flexible tube substrate having a porous layer was immersed in the primer layer-forming coating liquid prepared above at room temperature for 1 minute, air-dried for 10 minutes, and then placed in an oven at 100°C and heated and dried for 10 minutes to prepare a flexible tube substrate having a primer layer on a porous layer (flexible tube substrate used in Example 1). In the same manner as above, flexible tube substrates used in each Example and Comparative Example were prepared using the coupling agents listed in Table 3. In the Comparative Examples, an intermediate layer was formed instead of the porous layer used in the Examples. In Comparative Example 4, no primer layer was formed.

[0109] <Formation of polymer coating layer> The flexible tube substrate, which had a primer layer on a porous layer, was extrusion-coated with the polymers listed in Table 3 (Tables 3-1 and 3-2) (molding temperature: polymer melting point + 10°C) to produce a flexible tube for endoscopes with a polymer coating layer. The thickness of the polymer coating layer was 0.4 mm (in the case of a two-layer structure, the combined thickness of the two layers was 0.4 mm). In the case where the polymer coating layer was two layers (Examples 1 to 36, 44 to 51, Comparative Examples 1 to 4, 6 to 8), the two layers were simultaneously coated by two-layer extrusion molding. In this case, the ratio of the inner and outer layers at the front and rear ends was inner layer:outer layer = 80:20 at the front end and inner layer:outer layer = 20:80 at the rear end. The thicknesses of the inner and outer layers were graded from the front end to the rear end.

[0110] The following tests were carried out on the manufactured flexible tubes, and the results are summarized in Table 3 below.

[0111] [Test Example 1] Evaluation of the elasticity of flexible tubes In an environment with a temperature of 25°C and a relative humidity of 50%, the flexible tube for endoscopes prepared above was fixed at positions 30 cm and 50 cm from one tip, and the flexible tube was pushed 15 mm in the direction perpendicular to its length (diameter direction) at a position 40 cm from the tip (the center of the flexible tube). The ratio of the repulsive force (b) after 30 seconds to the repulsive force (a) after 0.1 seconds was calculated as the elasticity (%). The repulsive force was measured using a force gauge (ZTS50N (trade name), manufactured by IMADA). [Elasticity (%)] = [(b) / (a)] x 100 The resilience was evaluated according to the following evaluation criteria. A grade of "C" or higher is acceptable. <Resilience evaluation criteria> A: Elasticity is 80% or more B: Elasticity is 75% or more but less than 80% C: Elasticity is 65% or more but less than 75% D: Elasticity less than 65%

[0112] [Test Example 2] Evaluation of bending durability (adhesion) of flexible tube The flexible tube for endoscopes prepared above was placed in contact with half of a 7cm diameter pulley so that it formed a U-shape, and was reciprocated so that the front and rear ends were positioned 3.5cm in front of the end of the pulley, and the condition of the polymer coating layer was visually observed. The number of reciprocations at which lifting, tearing, or peeling of the polymer coating layer occurred was evaluated according to the following evaluation criteria. A grade of "C" or higher was considered acceptable. <Bending durability evaluation criteria> A: Over 10,000 times B: 1,000 to less than 10,000 times C: 100 to less than 1,000 times D: Less than 100 times

[0113] [Test Example 3] Evaluation of thermal cycle resistance of flexible tube The flexible tube for endoscopes prepared above was subjected to 500 cycles of heat cycle testing, with one cycle consisting of 2 hours at 0°C and 2 hours at 60°C, using a thermo-hygrostat (KHWV-40HP (trade name) manufactured by Satake Chemical Machinery Co., Ltd.). After 500 cycles of the heat cycle testing, the flexible tube for endoscopes was measured for repulsive force (c) 0.1 seconds after being pushed in, in the same manner as in Test Example 1. The ratio of repulsive force (c) to repulsive force (a) measured in the same manner as in Test Example 1 before the heat cycle testing was calculated as the repulsive force maintenance rate (%). [Rebound force retention rate (%)] = [(c) / (a)] x 100 The resilience retention rate was evaluated according to the following evaluation criteria, with "C" or higher being acceptable. <Thermal cycle resistance evaluation criteria> A: Rebound force retention rate is 90% or more B: Rebound force retention rate is 70% or more but less than 90% C: Rebound force retention rate is 50% or more but less than 70% D: Rebound force retention rate is less than 50%

[0114] [Table 3-1]

[0115] [Table 3-2]

[0116] <Notes for Table 3> The abbreviations listed in the above table are as follows:

[0117] Example: Ratio: Comparative Example

[0118] (Silane coupling agent) (S-1): N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (trade name: KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-2): 3-Aminopropyltrimethoxysilane (trade name: KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-3): N-methylaminopropyltrimethoxysilane (reagent) (S-4): 3-Ureidopropyltrialkoxysilane (trade name: KBE-585, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-5): N-phenyl-3-aminopropyltrimethoxysilane (trade name: KBM-573, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-6): 3-Trimethoxysilylpropylsuccinic anhydride (trade name: X-12-967C, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-7): (3-Methacryloxypropyl)trimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-8): 3-Glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-9): 3-Mercaptopropyltrimethoxysilane (trade name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0119] (aluminum coupling agent) (A-1): Aluminum sec-butoxide (product name: ASBD, manufactured by Kawaken Fine Chemicals Co., Ltd.) (A-2): Aluminum trisacetylacetonate (trade name: Orgatix AL-3100, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-3): Aluminum bisethylacetoacetate monoacetylacetonate (trade name: Orgatix AL-3200, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-4): Aluminum trisethylacetoacetate (trade name: Orgatix AL-3215, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-5): Aluminum octadecyl acetoacetate diisopropylate (product name: PLENACT AL-M, manufactured by Ajinomoto Fine-Techno Co., Inc.)

[0120] (Zirconium coupling agent) (Z-1): Zirconium tetra-n-propoxide (trade name: Orgatix ZA-45, manufactured by Matsumoto Fine Chemical Co., Ltd.) (Z-2): Zirconium tetra-n-butoxide (trade name: Orgatix ZA-65, manufactured by Matsumoto Fine Chemical Co., Ltd.) (Z-3): Zirconium tetraacetylacetonate (trade name: Orgatix ZC-150, manufactured by Matsumoto Fine Chemical Co., Ltd.) (Z-4): Zirconium lactate ammonium salt (trade name: Orgatix ZC-300, manufactured by Matsumoto Fine Chemical Co., Ltd.) (Z-5): Zirconium stearate tri-n-butoxide (trade name: Orgatix ZC-320, manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0121] (Titanium coupling agent) (T-1): Tetra n-butyl titanate (trade name: Orgatix TA-21, manufactured by Matsumoto Fine Chemical Co., Ltd.) (T-2): n-Butyl titanate dimer (trade name: Orgatix TA-23, manufactured by Matsumoto Fine Chemical Co., Ltd.) (T-3): Isopropyl triisostearoyl titanate (trade name: PLENACT TTS, manufactured by Ajinomoto Fine-Techno Co., Inc.) (T-4): Dioctylbis(ditridecyl)phosphate titanate (trade name: PLENACT 46B, manufactured by Ajinomoto Fine-Techno Co., Inc.) (T-5): Diisopropyl bis(dioctyl pyrophosphate) titanate (trade name: PLENACT 38S, manufactured by Ajinomoto Fine-Techno Co., Inc.)

[0122] (U-1): Polyether polyurethane elastomer (trade name: Pandex T-8185, manufactured by DIC Corporation) (U-2): Polyether polyurethane elastomer (product name: Miractoran E380, manufactured by Nippon Polyurethane Co., Ltd.) (U-3): Polyester polyurethane elastomer (product name: Miractoran E480, manufactured by Nippon Polyurethane Co., Ltd.) (U-4): Polycarbonate polyurethane elastomer (product name: Pandex T-9280, manufactured by DIC Corporation) (E-1): Polyester elastomer (product name: Pelprene P-40B, manufactured by Toyobo Co., Ltd.) (Ae-1): Polyamide elastomer (trade name: Pebax 4533, manufactured by Arkema) (P-1): Polyolefin elastomer: Zelas MC707 (product name), manufactured by Mitsubishi Chemical Corporation (F-1): Fluorine-containing elastomer: Daiel T-530 (product name), manufactured by Daikin Industries, Ltd.

[0123] The above table reveals the following: The flexible tubes of Comparative Examples 1 and 6 to 8, which do not have the porous layer defined in the present invention, are inferior in adhesion and heat resistance even though they have a primer layer. The flexible tube of Comparative Example 2 has an epoxy resin layer between the flexible tube substrate and the primer layer. However, because this epoxy resin layer is not porous, it has poor adhesion and heat resistance. Similarly, the flexible tube of Comparative Example 3 has a non-porous silica layer between the flexible tube substrate and the primer layer, and it also has poor adhesion and heat resistance. The flexible tube of Comparative Example 4 has a porous layer as defined in the present invention, but does not have a primer layer as defined in the present invention, and is inferior in adhesion and heat resistance. The flexible tube of Comparative Example 5 has a fluorine-containing elastomer layer as a polymer coating layer. In other words, it does not have the polymer coating layer defined in the present invention. This flexible tube is inferior in all of elasticity, adhesion, and heat resistance. In contrast, the flexible tubes of Examples 1 to 51 of the present invention have sufficient elasticity, excellent adhesion, and also excellent heat resistance. [Explanation of symbols]

[0124] 2. Electronic endoscope (endoscope) 3 Insertion section 3a flexible tube 3b Angle part 3c Tip 5 Main unit operation section 6 Universal Code 11 Spiral tube 11a metal strip 12 Cylindrical mesh body 13. Base 14 Flexible tube base material 14a Tip side 14b Base end 15 Polymer coating layer 16 Topcoat layer 17 Inner layer 18 Outer layer X Angle part 3b side (soft) Y Main unit operation part 5 side (hard) 20 Continuous molding machine (manufacturing equipment) 21, 22 Extrusion section 21a screw 22a screw 23 Head 24 Cooling section 25 Conveyor 26 Control Unit 28 Supply drum 29 Winding drum 30 Joint material 31 Connected flexible tube base material 32 nipple 33 Dice 34 Support Gates 35 and 36 37 Molding passage 38 Polymer Passage 39 First polymer material (soft polymer) 40 Second polymer material (hard polymer)

Claims

1. The flexible tube has a flexible tube substrate made of a metal, a porous layer on the flexible tube substrate, a primer layer on the porous layer, and a polymer coating layer on the primer layer, A flexible tube for an endoscope, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer.

2. 2. The flexible tube for an endoscope according to claim 1, wherein the porous layer contains a polymer compound and the average pore size of the porous layer is 50 nm to 100 μm.

3. 3. The flexible tube for an endoscope according to claim 1, wherein the primer layer contains at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent.

4. The flexible tube for an endoscope according to any one of claims 1 to 3, wherein the primer layer contains a silane coupling agent.

5. The flexible tube for an endoscope according to any one of claims 1 to 4, wherein the primer layer contains an aminosilane coupling agent.

6. 6. The flexible tube for an endoscope according to claim 1, wherein the metal constituting the flexible tube base material is stainless steel.

7. 7. The flexible tube for an endoscope according to claim 1, wherein the metal constituting the flexible tube base material has a passivation film on the surface.

8. The flexible tube for an endoscope according to any one of claims 1 to 7, wherein the polymer coating layer has a single-layer structure or a multi-layer structure, and a layer in contact with the primer layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin.

9. The flexible tube for an endoscope according to any one of claims 1 to 8, wherein the polymer coating layer has a two-layer structure, and the thickness ratio between the inner layer and the outer layer of the two-layer structure changes gradually in the axial direction of the flexible tube base material.

10. 10. The flexible tube for an endoscope according to claim 9, wherein a thickness ratio of the inner layer to the outer layer is inner layer:outer layer=95:5 to 60:40 at one end of the flexible tube for an endoscope, and inner layer:outer layer=5:95 to 40:60 at the other end.

11. An endoscopic medical device comprising the flexible tube for an endoscope according to any one of claims 1 to 10.

12. The method includes providing a porous layer having an average pore size of 50 nm to 100 μm on a flexible tube substrate made of metal, providing a primer layer on the porous layer, and providing a polymer coating layer on the primer layer, A method for manufacturing a flexible tube for an endoscope, wherein the polymer coating layer contains at least one compound selected from the group consisting of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer.

13. A method for producing an endoscopic medical instrument, comprising incorporating the flexible tube for an endoscope obtained by the method for producing a flexible tube for an endoscope according to claim 12 into an insertion portion of the endoscopic medical instrument.

14. A method for manufacturing an endoscopic medical device, comprising incorporating the flexible tube for an endoscope according to any one of claims 1 to 10 into an insertion portion of the endoscopic medical device.

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