Flexible tube for endoscopes, endoscopic medical devices, and methods 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 endoscope-type medical device, and methods for producing the same. [Background Art]

[0002] An endoscope is a medical device for observing the inside of a patient's body cavities, the inside of the digestive tract, the esophagus, and the like. Since it is used by being inserted into the body, it is desirable that it does not damage organs and does not cause pain or discomfort to the patient. In response to such requirements, the flexible tube constituting the insertion section of an endoscope (the structural section inserted into a body cavity) employs a spiral tube formed by helically winding a soft and bendable metal strip. Furthermore, the periphery of the spiral tube is covered with a flexible polymer, and this polymer coating layer is optionally covered with a top coat layer, which is designed so as not to cause irritation or damage to the inner surfaces of the esophagus, digestive tract, body cavity and the like.

[0003] This flexible tube is required to have high resilience to allow smooth movement inside the body. By increasing the resilience of the flexible tube, the flexible tube that has passed through a bent part in the body can easily return to a straight shape, which can further reduce the burden on the subject during examination. As a technology that meets such requirements, for example, Patent Document 1 discloses that after applying a primer to the surface of a metal core material (flexible tube base material), an outer skin layer is coated and molded, and that a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, and a zirconium-based coupling agent can be used as the primer. According to Patent Document 1, this flexible tube for endoscopes is said to be excellent in resilience. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2010-035923 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] On the other hand, improving the operability and durability of endoscopes requires increasing the adhesion between the flexible tube base material and the polymer coating layer covering it. If this adhesion is insufficient, when the flexible tube is inserted into the body, the bending of the flexible tube can easily cause wrinkles, lifting, tears, or peeling of the polymer coating layer. Furthermore, when the flexible tube is rotated while inserted, the polymer coating layer is prone to twisting. If wrinkles, lifting, tears, peeling, or twisting occur in the polymer coating layer, the surface of the flexible tube inserted into the body may catch on surrounding tissues, potentially causing pain to the patient. However, the endoscopic flexible tube described in Patent Document 1 above does not fully meet the requirements for adhesion between the flexible tube base material and the polymer coating layer.

[0006] Furthermore, during use, endoscopes are exposed to heat generated from the light source of the built-in illumination, etc. Endoscopes may also be exposed to heat up to about 60°C during disinfection or sterilization using chemical solutions. The inventors have found that repeated use of endoscopes exposes the flexible tube to heat cycles, resulting in a decrease in elasticity. Therefore, flexible tubes for endoscopes are also required to have properties that are less affected by heat cycles (they do not lose elasticity even when repeatedly heated).

[0007] The present invention aims to provide a flexible tube for endoscopes that exhibits excellent elasticity, maintains sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending, and is less susceptible to a decrease in elasticity even after repeated heating, as well as an endoscopic medical device equipped with this flexible tube. The present invention also aims to provide a method for manufacturing the above-mentioned flexible tube for endoscopes, and a method for manufacturing the above-mentioned endoscopic medical device. [Means for solving the problem]

[0008] In view of the above problems, the inventors of this invention have conducted extensive research on the formation of a polymer coating layer in a flexible tube for endoscopes. As a result, they have found that the above 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 applying a specific type of polymer as the constituent material of the polymer coating layer in contact with this primer layer. This invention was completed after further research based on these findings.

[0009] The above-mentioned problems of the present invention were solved by the following means. <1> The flexible tube substrate comprises a metal as a constituent material, 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 endoscopes, wherein the polymer coating layer contains at least one compound 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> A flexible tube for endoscopes as described above. <3> The above-mentioned 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> A flexible tube for endoscopes as described above. <4> The above primer layer contains a silane coupling agent. <1> ~ <3> A flexible tube for endoscopes as described in any one of the following. <5> The above primer layer contains an aminosilane coupling agent. <1> ~ <4> A flexible tube for endoscopes as described in any one of the following. <6> The metal constituting the flexible pipe base material is stainless steel. <1> ~ <5> A flexible tube for endoscopes as described in any one of the following. <7> The metal constituting the above flexible tube base material has a passivation film on its surface. <1> ~ <6> A flexible tube for endoscopes as described in any one of the following. <8> The polymer coating layer has a single-layer or multi-layer structure, and the layer in contact with the primer layer contains at least one compound of polyamide, polyester, polyurethane, and polyolefin. <1> ~ <7> A flexible tube for endoscopes as described in any one of the following. <9> The polymer coating layer has a two-layer structure, and the ratio of the thicknesses of the inner and outer layers of the two-layer structure changes in a gradual manner along the axial direction of the flexible tube substrate. <1> ~ <8> A flexible tube for endoscopes as described in any one of the following. <10> The ratio of the thickness of the inner and outer layers is such that at one end of the flexible tube for endoscopy, the ratio of inner layer:outer layer = 95:5 to 60:40, and at the other end, the ratio of inner layer:outer layer = 5:95 to 40:60. <1> ~ <9> A flexible tube for endoscopes as described in any one of the following. <11> <1> ~ <10> An endoscopic medical device having a flexible tube for endoscopy as described in any one of the following. <12> This method includes providing a porous layer with 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 of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer. <13> <12> A method for manufacturing an endoscopic medical device, comprising incorporating an endoscopic flexible tube obtained by the method for manufacturing an endoscopic flexible tube described above into the insertion part of an endoscopic medical device. <14> <1> ~ <10> A method for manufacturing an endoscopic medical device, comprising incorporating a flexible tube for endoscopes described in any one of the above into the insertion part of the endoscopic medical device.

[0010] In this specification, when there are multiple substituents or linking groups indicated by specific symbols (hereinafter referred to as substituents, etc.), or when multiple substituents, etc. are specified simultaneously or alternatively, it means that each substituent, etc. may be identical or different from the others. Furthermore, even if not specifically stated otherwise, when multiple substituents, etc. are adjacent to each other, they may be linked to each other or fused to form a ring. In this specification, substituents (and linking groups) that are not explicitly stated as substituted or unsubstituted may have any substituents as long as the desired effect is achieved. This also applies to compounds that are not explicitly stated as substituted or unsubstituted. In this specification, when the number of carbon atoms in a group is specified, this number refers to the total number of carbon atoms in the group. That is, if the group has further substituents, it refers to the total number of carbon atoms including those substituents. [Effects of the Invention]

[0011] The flexible tube for endoscopes of the present invention exhibits excellent elasticity, maintaining sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending, and is less prone to a decrease in elasticity even when exposed to heat cycles associated with repeated use of endoscopes. The endoscopic medical device of the present invention features a flexible tube, which is a structural component inserted into the body. This tube exhibits excellent elasticity, maintaining sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending. Furthermore, it is less susceptible to deterioration of elasticity even when exposed to heat cycles associated with repeated use. Therefore, the endoscopic medical device of the present invention offers superior durability and can further reduce the burden on the patient during use. According to the method for manufacturing a flexible tube for endoscopes of the present invention, it is possible to obtain a flexible tube for endoscopes 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 less susceptible to a decrease in elasticity even when exposed to heat cycles associated with repeated use of endoscopes. According to the method for manufacturing an endoscopic medical device of the present invention, the flexible tube constituting the device has excellent resilience, and sufficient adhesion between the flexible tube base material and the polymer coating layer covering the same can be maintained even after repeated bending operations. In addition, the flexible tube can have a characteristic that resilience is less likely to decrease even when exposed to heat cycles accompanying repeated use of an endoscope. Therefore, with the method for manufacturing an endoscopic medical device of the present invention, an endoscopic medical device having excellent durability and a reduced burden on a subject during use can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1] It is an external view showing a configuration of an embodiment of an electronic endoscope. [Figure 2] It is a partial cross-sectional view showing a configuration of an embodiment of a flexible tube for an endoscope. [Figure 3] It is a block diagram showing a configuration of an embodiment of a manufacturing apparatus for a flexible tube for an endoscope. [Figure 4] It is a cross-sectional view taken along line B-B in FIG. 3. MODE FOR CARRYING OUT 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 "flexible tube") will be described using an electronic endoscope as an example. An electronic endoscope is used as a medical device for observing the inside of the body by inserting the flexible tube into a body cavity, the digestive tract, the esophagus, etc. In the example shown in Figure 1, the electronic endoscope 2 comprises an insertion section 3 that is inserted into the body, a main unit operation section 5 connected to the base end of the insertion section 3, and a universal cord 6 connected to a processor device and a light source device. The insertion section 3 consists of a flexible tube 3a connected to the main unit operation section 5, an angle section 3b connected thereto, and a tip section 3c connected to its tip, which contains an imaging device (not shown) for internal imaging. The flexible tube 3a, which occupies most of the length of the insertion section 3, is flexible along almost its entire length, and the part that is inserted into the inside of a body cavity, etc., has a structure that is particularly flexible. In Figure 1, the angle section 3b has a soft structure (soft), while the main body operating section 5 has a hard structure (hard).

[0014] [Flexible tube for endoscope] The flexible tube for endoscopes of the present invention comprises 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, 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 endoscopes comprises a flexible tube base material 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. Note that the porous layer and primer layer are not shown in Figure 2.

[0015] The flexible tube for endoscopes of the present invention exhibits excellent elasticity, maintaining sufficient adhesion between the flexible tube base material and the polymer coating layer covering it even after repeated bending, and is less prone to loss of elasticity even after repeated heating. Although the reason for this is not entirely clear, it is presumed that one contributing factor is the anchoring effect in which the polymer coating layer penetrates the pores of the porous layer while 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 Figure 2, the flexible tube base material 14 is preferably formed by covering a spiral tube 11, which is created by spirally winding a metal strip 11a on the innermost part, with a cylindrical mesh body 12 made of braided metal wires, and fittings 13 to both ends. The metal constituting the flexible tube base material 14 is preferably subjected to a passivation treatment on its surface to prevent corrosion. That is, the flexible tube base material 14 preferably has a passivation film (for example, a metal oxide film) on its outer circumference. This passivation treatment can be carried out by conventional methods. For example, a passivation film can be formed on the metal surface by immersion in a solution containing a strong oxidizing agent such as nitric acid, heating in air (oxygen) or water (steam), or anodic oxidation in a solution containing an oxidizing agent. The metal constituting the flexible tube base material 14 is preferably stainless steel. The surface of stainless steel is normally in a state where a passivation film is formed by the bonding of chromium and oxygen. However, even when using stainless steel as the constituent material of the flexible tube base material 14, it is preferable to apply the passivation treatment described above to the stainless steel in order to more reliably form a more uniform passivation film over the entire surface of the stainless steel.

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

[0018] The average pore size of the porous layer is not particularly limited, but from the viewpoint of elasticity, adhesion and heat resistance, for example, 50 nm to 300 μm is preferred, 70 nm to 100 μm is more preferred, 150 nm to 100 μm is even more preferred, 300 nm to 25 μm is even more preferred, 450 nm to 25 μm is even more preferred, and 450 nm to 5 μm is even more preferred. 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, but is preferably 10-80%, more preferably 20-60%, and even more preferably 30-50%. In this specification, "porosity" is 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, but is preferably 0.01 to 1000 μm, more preferably 0.05 to 500 μm, and even more preferably 0.1 to 50 μm. In this 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 this 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, with crosslinked epoxy resins being more preferred.

[0022] The content of the polymer compound in the porous layer is not particularly limited; for example, 80% by mass or more is preferred, and 90% by mass or more is more preferred. The porous layer may also be a layer made of a polymer compound (a polymer compound layer having pores). The porous layer may contain, in addition to polymer compounds, plasticizers, flame retardants, reinforcing agents (e.g., inorganic fillers and metal fillers), and stabilizers such as antioxidants, to the extent that they do not impair the effects of the present invention.

[0023] As a porous layer containing a crosslinked epoxy resin (hereinafter also referred to as the "epoxy resin porous layer"), for example, the epoxy resin porous membrane described in Japanese Patent Publication No. 2010-77358 and Japanese Patent Publication No. 2013-18966 can be applied as the porous layer constituting the flexible tube of the present invention.

[0024] As a porous layer containing siloxane (hereinafter also referred to as the "silica porous layer"), for example, the silica-based porous membrane described in Japanese Patent Publication No. 2010-64932, the mesoporous silica thin film described in International Publication Nos. 2003 / 028097 and International Publication Nos. 2003 / 075335, the porous silica membrane described in Japanese Patent Publication No. 2003-115486, the porous silica membrane described in Japanese Patent Publication No. 2005-202240, and the porous silica membrane described in Japanese Patent Publication No. 2003-268356 can be applied as the porous layer constituting the flexible tube of the present invention.

[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 viewpoint 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. In the present invention, a wide range of conventional silane coupling agents applicable to the primer layer of a flexible tube for endoscopes can be used as the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent. In the present invention, a silane coupling agent is preferred from the viewpoint 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, and an aminosilane coupling agent (preferably a silane coupling agent having at least one of an unsubstituted amino group and a monosubstituted amino group) is more preferred. Specific examples of silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents include those used in the examples described later, but the present invention is not limited to these. 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 even more preferably 90% by mass or more. The primer layer may also consist 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 even more preferably 90% by mass or more. The primer layer described above may contain components other than silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents, as long as the effects of the present invention are not impaired. Examples of such components include metal alkoxides other than the coupling agents, binder resins, and stabilizers (e.g., surfactants and antioxidants).

[0026] In the present invention, "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 the primer layer contains at least one of the silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent in a state in which it has reacted with the porous layer or flexible tube substrate, and that the primer layer contains at least one of the silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent in a state in which it has reacted with the polymer coating layer. For example, at least a portion of the silane coupling agent, titanium coupling agent, zirconium coupling agent, and aluminum coupling agent may be hydrolyzed to expose hydroxyl groups, which may then react with the constituent metals of the porous layer or flexible tube substrate, or with the groups on the surface of the polymer coating layer.

[0027] The thickness of the primer layer described above is significantly thinner than that of a typical adhesive layer, and while not limited, it is preferably between 1 nm and 100 nm. In other words, the primer layer differs from the adhesive layer, which requires a certain thickness and flexibility for bonding between 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 circumference of a flexible tube substrate in which a porous layer and a primer layer are provided in that order. In the configuration shown in Figure 2, the outer surface of the polymer coating layer 15 is coated with a topcoat layer 16 containing fluorine or the like, which contributes to chemical resistance. In Figure 2, only one spiral tube 11 is shown, but it may be constructed by stacking two or more layers coaxially. In the drawing, the polymer coating layer 15 and the topcoat layer 16 are depicted as thicker than the diameter of the flexible tube base material 14 in order to clearly illustrate the layer structure.

[0029] In the present invention, the polymer coating layer covers the outer surface of the flexible tube substrate having the porous layer and primer layer described above. In the embodiment shown in Figure 2, the polymer coating layer 15 has a two-layer structure, consisting of an inner layer 17 that covers the entire circumferential surface of the flexible tube substrate 14 around its axis, and an outer layer 18 that covers the entire circumferential surface of the inner layer 17 around its axis. Typically, a soft polymer is used for the inner layer 17 and a hard polymer is used for the outer layer 18, but the present invention is not limited to these embodiments. In the present invention, as described later, when the polymer coating layer has a multilayer structure of two or more layers, at least the innermost layer (the layer in contact with the primer layer) contains at least one compound from polyamide, polyester, polyurethane, and polyolefin. Also, in the present invention, when the polymer coating layer is a single layer, this single layer of polymer coating contains at least one compound from polyamide, polyester, polyurethane, and polyolefin. In other words, in the present invention, it is preferable that the polymer coating layer contains at least one compound from polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer, and at least one compound 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 applicable as polymer coating layers for flexible tubes for endoscopes can be used. Examples include crystalline polyamides, amorphous polyamides, and polyamide elastomers. There are no particular restrictions on crystalline polyamides; for example, aliphatic polyamides and aromatic polyamides can be mentioned. Examples of aliphatic polyamides include poly-ε-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), and polydodecamido (polyamide 6 / 11). Examples include polyamide 12), polycaproamide / polydodecamido copolymer (polyamide 6 / 12), polyhexamethylene sevacamide (polyamide 610), polydecamethylene sevacamide (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), and polyhexamethylene. Examples include adipamide / polyhexamethylene isophthalamide copolymer (polyamide 66 / 6I), polytrimethylhexamethylene terephthalamide (polyamide TMDT), polybis(4-aminocyclohexyl)methanedodecamamide (polyamide PACM12), polybis(3-methyl-4-aminocyclohexyl)methanedodecamamide (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 the polycondensate of isophthalic acid / terephthalic acid / 1,6-hexanediamine / bis(3-methyl-4-aminocyclohexyl)methane, the polycondensate of terephthalic acid / 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine, the polycondensate of isophthalic acid / bis(3-methyl-4-aminocyclohexyl)methane / ω-laurolactam, and the polycondensate of isophthalic acid / terephthalic acid / 1,6-hexanediamine. Examples include polycondensates of isophthalic acid / 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine, polycondensates of isophthalic acid / 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 / other diamine components.

[0033] Examples of polyamide elastomers include elastomers called amide-based thermoplastic elastomers, in which the hard segment is polyamide. For example, examples include multiblock copolymers in which the hard segment is polyamide and the soft segment is polyether or polyester, and multiblock copolymers in which the hard segment is polyamide and the soft segment has both ether and ester bonding modes. Examples of hard segments include polyamide 6, 66, 610, 11, and 12. Examples of polyethers in the soft segment include polyethylene glycol, diol poly(oxytetramethylene) glycol, and poly(oxypropylene) glycol, while examples of polyesters include poly(ethylene adipate) glycol and poly(butylene-1,4-adipate) glycol.

[0034] Examples of commercially available polyamides that can be used in the present invention include polyamide 11 (Arkema, trade name "Lilsan BMN O"), polyamide 12 (Daicel-Evonik, trade name "Diamide L1940"), polyamide 1010 (Daicel-Evonik, trade name "Vestamide Terra DS16"), polyamide 1012 (Evonik, trade name "Vestamide Terra DD16"), amorphous polyamide (Daicel-Evonik, trade name "Trogamide CX7323"), and polyamide elastomers (Arkema, trade names "Pebax 4533", "Pebax 7233", and "Pebax Rnew 80R53").

[0035] Polyamides may be used individually or in combination of two or more types.

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

[0037] Furthermore, 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 hydroxycarboxylic acid components 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 a copolymer, and may also contain a small amount of trifunctional compound components such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, or pentaerythritol.

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

[0041] Examples of commercially available polyesters used in this invention include polyester elastomers (product names "Perprene P-40B," "Perprene P-70B," and "Perprene S-3001" from Toyobo Co., Ltd., and "Primaloy B1942" from Mitsubishi Chemical Corporation) and polybutylene terephthalate (product name "Novaduran 5505S" from Mitsubishi Engineering Plastics Corporation).

[0042] Polyester may be used alone or in combination of two or more types.

[0043] (Polyurethane) As the polyurethane, a wide range of ordinary polyurethanes applicable as polymer coating layers for 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, referred to as urethane-based thermoplastic elastomers, in which the hard segment is polyurethane and the soft segment has ether, ester, or carbonate bonds, or a mixture thereof, which can be appropriately prepared depending on the purpose. For example, a block polymer containing a hard segment consisting of low molecular weight glycol and diisocyanate components and a soft segment consisting of high molecular weight (long-chain) diol and diisocyanate components can be used. Examples of high-molecular-weight (long-chain) diol components include polyether diols, polyester diols, and lactone-based polyester diols. For example, 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 high-molecular-weight (long-chain) diol is preferably 500 to 10,000. As low molecular weight glycol components, 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 to 500. Examples of the diisocyanate components mentioned above include diphenylmethane diisocyanate, hexamethylene diisocyanate, tolidine diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate.

[0044] For example, one can refer to the disclosure in Japanese Patent Application Publication No. 2005-015643 regarding the polyurethane elastomer according to the above embodiment.

[0045] Examples of commercially available polyurethanes that can be used in this invention include PANDEX T-2185, T-2983N (both manufactured by DIC Corporation), Miractran (manufactured by Nippon Miractran Co., Ltd.), Pandex (manufactured by DIC Corporation), Elastran (manufactured by BASF Japan), Rezamin (manufactured by Dainichi Seika Kogyo Co., Ltd.), Peresen (manufactured by Dow Chemical Japan Co., Ltd.), Iron Rubber (manufactured by NOK Corporation), and Mobilon (manufactured by Nisshinbo Chemical Co., Ltd.). Examples include Isoplast (manufactured by Lubrizol), Tecoflex (manufactured by Lubrizol), Superflex 830, 460, 870, 420, or 420NS (polyurethane manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Hydran AP-40F, WLS-202, or HW-140SF (polyurethane manufactured by DIC Corporation), Olestar UD500, or UD350 (polyurethane 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] Polyurethane may be used alone or in combination of two or more types.

[0047] (Polyolefin) As the polyolefin, a wide range of ordinary polyolefins applicable as polymer coating layers for flexible tubes for endoscopes can be used. Examples include 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 with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene. Furthermore, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, propylene-α-olefin copolymer rubber, and butene-α-olefin copolymer rubber are also possible. In addition, 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 copolymer, ethylene-1-butene copolymer, ethylene-α-olefin copolymer, propylene-1-butene copolymer, propylene-α-olefin copolymer, 1-butene-α-olefin copolymer, propylene-1-butene-ethylene copolymer, propylene-α-olefin-ethylene copolymer, propylene-α-olefin-1-butene copolymer, 1-butene-α-olefin-ethylene copolymer, and polypropylene. Examples of rubber components in olefin-based elastomers include propylene rubber (PP), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polyisoprene, polybutadiene, polychloroprene, and isobutylene-isoprene copolymers. In olefin-based elastomers, polyolefins and rubber components may be present individually or in combination of two or more types.

[0050] Examples of commercially available polyolefins used in the present invention include "Sarlink 3145D" (trade name, manufactured by Toyobo Co., Ltd.) and "Zelus MC707" (trade name, manufactured by Mitsubishi Chemical Corporation).

[0051] Polyolefins may be used individually or in combination of two or more types.

[0052] When the polymer coating layer is a single layer, the total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the polymer coating layer, and when the polymer coating layer is a multi-layer, the total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the innermost layer, are 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 composed of at least one compound of polyamide, polyester, polyurethane, and polyolefin, and when the polymer coating layer is a multi-layer, the innermost layer may be a layer composed of at least one compound of polyamide, polyester, polyurethane, and polyolefin. When the polymer coating layer is a single layer, and when the polymer coating layer is a multi-layered layer, the innermost layer contains a polymer other than a polymer selected from polyamide, polyester, polyurethane, and polyolefin, there are no particular restrictions on this 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 they do not impair the effects of the present invention. Examples of such additives include heat stabilizers, inorganic fillers, impact enhancers, plasticizers, lubricants, metal soaps, light stabilizers, and colorants. The content of these additives in the polymer coating layer can also be adjusted as appropriate. Such additives may originate from the polymer material used, or they may be added separately from the polymer.

[0053] In the case of a multilayer polymer coating, it is preferable that the layers other than the innermost layer also contain at least one compound from polyamide, polyester, polyurethane, and polyolefin. These polymers can be appropriately combined to form layers with desired physical properties. The total content of compounds selected from polyamide, polyester, polyurethane, and polyolefin in the layers other than the innermost layer is equivalent to the total content in the innermost layer.

[0054] The 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 this invention, unless otherwise specified, the molecular weight of the polymer constituting the polymer coating layer refers to the weight-average molecular weight. The weight-average molecular weight can be measured as the molecular weight in terms of polystyrene by gel permeation chromatography (GPC).

[0055] As shown in Figure 2, in the present invention, it is preferable that the polymer coating layer 15 is formed with a substantially uniform thickness in the longitudinal direction (axial direction) of the flexible tube base material 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, it is 11 to 14 mm. In Figure 2, the thicknesses of the inner layer 17 and the outer layer 18 are formed such that the ratio of the thickness of each layer 17 and 18 to the total thickness of the polymer coating layer 15 changes in the axial direction of the flexible tube base material 14. Specifically, at one end 14a (tip side) of the flexible tube base material 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. Then, from one end 14a toward the other end 14b (base end) which is attached to the main unit operating section 5, the thickness of the inner layer 17 gradually decreases, and at the other end 14b, the thickness of the outer layer 18 is greater than the thickness of the inner layer 17.

[0056] In Figure 2, the ratio of the thickness of the inner layer 17 is maximum at one end 14a, and the ratio of the thickness of the outer layer 18 is maximum 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 both layers are changed so that the ratio of the thicknesses of the inner layer 17 and the outer layer 18 is reversed from both ends 14a to 14b. As a result, the flexible tube 3a has a difference in hardness between the one end 14a side and the other end 14b side, and its flexibility can be changed in the axial direction so that the one end 14a side is softer and the other end 14b side is harder. Preferably, the ratio of the thicknesses of the inner and outer layers at one end is 95:5 to 60:40 (inner layer:outer layer), and the ratio of the thicknesses at the other end is 5:95 to 40:60 (inner layer:outer layer). Furthermore, by setting the thickness ratio of the inner layer 17 to the outer layer 18 within the range of 95:5 to 5:95, it is possible to precisely control the extrusion amount of the thinner polymer.

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

[0058] <Top coat layer> In the flexible tube of the present invention, a topcoat layer 16 is optionally provided on the outer circumference of the polymer coating layer 15. The material of the topcoat layer is not particularly limited, and urethane paint, acrylic paint, fluoropolymer paint, silicone paint, epoxy paint, polyester paint, etc., can be used. The main purposes of using a topcoat layer are to protect the surface of the flexible pipe, to add gloss, to provide slipperiness, and to provide chemical resistance. Therefore, a topcoat layer with a high modulus of elasticity, a smooth surface, and excellent chemical resistance is preferable.

[0059] [Method for manufacturing flexible pipes] <Formation of porous layers> In the manufacturing of the flexible tube of the present invention, a porous layer is formed on the flexible tube substrate. The formation of the porous layer can be carried out by referring, for example, to Japanese Patent Publication No. 2010-77358, Japanese Patent Publication No. 2013-18966, Japanese Patent Publication No. 2010-64932, International Publication No. 2003 / 028097, International Publication No. 2003 / 075335, Japanese Patent Publication No. 2003-115486, Japanese Patent Publication No. 2005-202240, Japanese Patent Publication No. 2003-268356 and International Publication No. 2008 / 093731. The method for manufacturing a flexible tube of the present invention preferably includes forming a porous layer with an average pore diameter of 50 nm to 100 μm. As described later, the average pore diameter of the porous layer can be controlled by the raw materials of the porous layer, etc. The following describes in detail the methods for forming the epoxy resin porous layer and the silica porous layer. Note that the following description is an example, and the formation of the porous layer in this invention is not limited to these forms.

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

[0061] In step (i) above, a silica composition is obtained by dehydrating and condensing an alkoxysilane compound in a mixed solution containing an alkoxysilane compound, a pore-forming agent, and a solvent. For example, an alkoxysilane compound, a pore-forming agent, and a solvent containing water are mixed, and a catalyst described later is added as needed. While mixing, the alkoxysilane compound is subjected to a dehydration condensation reaction in the presence of the pore-forming agent, and the mixture is concentrated or diluted with the solvent as needed to obtain a silica composition. The reaction conditions (reaction temperature, reaction time) for the dehydration condensation reaction can 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 as appropriate. The above-mentioned tetraalkoxysilane is not particularly limited and includes, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Examples of trialkoxysilane compounds include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. Examples of dialkoxysilane compounds include dimethyldimethoxysilane and dimethyldiethoxysilane.

[0063] The silica content in the silica composition (content of the above-mentioned 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 still more preferably 1% by mass or more. On the other hand, the total content of the above-mentioned silane compound is preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and still more preferably 20% by mass or less.

[0064] As a pore-forming agent, one that is encapsulated in silica and can be decomposed and removed by heating can be used. Examples of pore-forming agents include surfactants. Nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be used, with nonionic surfactants being preferred, and nonionic surfactants with a polymer structure being more preferred. When the surfactant is a polymer, its number-average molecular weight is, for example, 300 to 5000.

[0065] The surfactant content 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. On the other hand, the above content is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

[0066] As a solvent, water or a combination of water and a water-soluble organic solvent is preferred. Examples of water-soluble organic solvents include alcohol compounds such as methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, and other monohydric alcohols having 1 to 4 carbon atoms, dihydric alcohols having 1 to 4 carbon atoms, and polyhydric alcohols such as glycerin and pentaerythritol; ethers or esterified versions 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; and acetone, methyl ethyl ketone, etc. Examples include ketone compounds; 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; and dimethyl sulfoxides. Among these, alcohols are preferred, and monohydric alcohols are more preferred, in order to perform hydrolysis under conditions that are more stable for the contained alkoxysilane compounds.

[0067] Silica compositions typically contain a catalyst. The catalyst can optionally be any substance that promotes the hydrolysis and dehydration condensation reactions of alkoxysilane compounds. Examples include acids such as hydrofluoric acid, phosphoric acid, boric acid, hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, maleic acid, methylmalonic acid, stearic acid, linolenic 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. Another example of a catalyst is a metal chelate compound. Examples of metal species in these metal chelate compounds include titanium, aluminum, zirconium, tin, and antimony.

[0068] The silica composition may contain components other than the alkoxysilane compound, organic solvent, surfactant, water, and catalyst described above, as long as they do not impair the effects of the present invention.

[0069] In step (ii) above, the flexible tube substrate is immersed in the silica composition obtained in step (i) above, and then the flexible tube substrate is removed and dried to form a coating film. Subsequently, the surfactant is decomposed and removed at a high temperature (e.g., 250°C or higher) to obtain 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 type of raw material, the mixing ratio of the raw materials, and the reaction conditions (e.g., 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 flexible tube substrate (outer circumference) through the following steps (1) to (3). (1) Prepare a mixture containing epoxy resin, a pore-forming agent, a solvent, and a curing agent for the epoxy resin. (2) The above mixture is applied to the flexible tube substrate, dried, and then heated to react the epoxy resin with the hardener. (3) Remove the pore-forming agent from the cured epoxy resin.

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

[0073] Aromatic epoxy resins and non-aromatic epoxy resins can be used as epoxy resins. Examples of aromatic epoxy resins include polyphenyl-based epoxy resins, epoxy resins containing fluorene rings, epoxy resins containing triglycidyl isocyanurate, and epoxy resins containing heteroaromatic rings (e.g., triazine rings). Examples of polyphenyl-based epoxy resins include bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, stilbene type epoxy resin, biphenyl type epoxy resin, bisphenol A novolac type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, and tetrakis(hydroxyphenyl)ethane-based epoxy resin. 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 glycidylamine type epoxy resins, and alicyclic glycidyl ester type epoxy resins. The epoxy resins described above may be used individually or in combination of two or more types.

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

[0075] The ratio of the curing agent content to the epoxy resin in the mixture of step (1) is preferably 0.1 to 1.5 equivalents of curing agent per equivalent of epoxy groups of epoxy resin, and more preferably 0.2 to 1.0.

[0076] Specific examples of pore-forming agents 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 individually or in combination of two or more.

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

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

[0079] In step (2) above, the flexible tube substrate is coated onto the surface of the flexible tube substrate by immersing it in the mixed solution obtained in step (1) above. Then, the solvent is removed by drying, and an epoxy resin layer can be formed on the flexible tube substrate by heating at approximately 60-120°C for 30 minutes to 4 hours.

[0080] In step (3) above, the flexible tube substrate is immersed in a solvent that does not dissolve the epoxy resin but dissolves the pore-forming agent, and the pore-forming agent is removed from the epoxy resin layer by ultrasonic treatment if necessary. Examples of solvents that do not dissolve the epoxy resin but dissolve the pore-forming agent 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 type of raw material, the mixing ratio of the raw materials, and the reaction conditions (for example, the heating temperature and heating time during reaction-induced phase separation).

[0082] In the present invention, to the extent that the effects of the present invention are not impaired, there may be a portion of the outer circumference of the flexible tube substrate that is not covered by the porous layer (i.e., a portion of the porous layer may have voids).

[0083] Before forming the porous layer, it is preferable to degrease and clean the flexible tube substrate with an acid solution, alkaline solution, surfactant aqueous solution, organic solvent, etc. Furthermore, after the above cleaning, it is preferable to further clean the substrate surface with water or warm water to reduce the amount of acid, alkali, surfactant, etc.

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

[0085] <Formation of polymer coating layer> The formation of the polymer coating layer will be explained using the case where the polymer coating layer has a two-layer structure as an example. 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) constituting the inner layer and a second polymer material constituting the outer layer around a flexible tube substrate on which the primer layer has been formed, extrude-molding, and coating the flexible tube substrate. Furthermore, embodiments with one or three or more polymer coating layers can also be obtained by appropriately changing the layer configuration by referring to the method described below.

[0086] An example of a method for forming a polymer coating layer on a flexible tube 3a (Figures 1 and 2) will be described based on Figures 3 and 4. In this configuration, a continuous molding machine is used to form the polymer coating layer 15. The continuous molding machine 20 preferably consists of well-known extrusion sections 21 and 22, which include a hopper, screws 21a and 22a, a head section 23 for coating the outer surface of the flexible tube base material 14 with the polymer coating layer 15, a cooling section 24, a transport section 25 (supply drum 28 and winding drum 29) for transporting the connected flexible tube base material 31 to the head section 23, and a control section 26 for controlling these. The head section 23 preferably consists of a nipple 32, a die 33, and a support 34 that fixedly supports them. As an example of the configuration of such an apparatus, for example, the apparatus described in Figures 3 to 5 of Japanese Patent Application Publication No. 2011-72391 can be used.

[0087] It is preferable to heat the inside of the die 33 to a predetermined molding temperature. The molding temperature is preferably set in the range of 150°C to 300°C. By heating and temperature-controlling the heating section in the apparatus, the temperatures of the first polymer material 39 and the second polymer material 40 can be raised to a high temperature. In addition, the higher the rotational 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, by keeping the transport speed of the connecting flexible tube base material 31 constant and changing the discharge amount of the molten first polymer material 39 and the second polymer material 40, the molding thickness of the inner layer 17 and the outer layer 18 can be adjusted.

[0088] The process for forming a polymer coating layer 15 on a connecting flexible pipe base material 31 using a continuous molding machine 20 is described below. When the continuous molding machine 20 performs the molding process, molten first polymer material 39 and second polymer material 40 are extruded from the extrusion sections 21 and 22 to the head section 23. Simultaneously, the transport section 25 operates to transport the connecting flexible pipe base material 31 to the head section 23. At this time, the extrusion sections 21 and 22 are constantly extruding the first polymer material 39 and second polymer material 40 and supplying them to the head section 23. The first polymer material 39 and second polymer material 40 extruded from the extrusion sections 21 and 22 to the gates 35 and 36 pass through the edges, merge, and are supplied in an overlapping state through the polymer passage 38 to the molding passage 37. As a result, a two-layer polymer coating layer 15 is formed, consisting of an inner layer 17 using the first polymer material 39 and an outer layer 18 using the second polymer material 40.

[0089] The connected flexible tube base material 31 is made up of multiple flexible tube base materials 14 (each of which has a porous layer and a primer layer formed on its outer circumference) connected together, and a polymer coating layer 15 is continuously formed on the multiple flexible tube base materials 14 while being transported through the molding passage 37. When forming the polymer coating layer 15 from one end 14a (tip side) to the other end 14b (base side) of a single flexible tube base material, the thickness of the inner layer 17 is made thicker immediately after the extrusion of the polymer by the extrusion sections 21 and 22 is started. Then, the ratio of the thickness of the outer layer 18 is gradually increased in the intermediate portion toward the other end 14b. It is preferable to control the amount of polymer extruded so that the thickness ratio of the polymer coating layer 15 is as described above.

[0090] Since the joint member 30 is the connecting part of the two flexible tube base materials 14, the control unit 26 is used to switch the discharge amount of the extrusion units 21 and 22. Specifically, it is preferable that the control unit 26 switches the discharge amount of the extrusion units 21 and 22 so that the ratio of the thickness at the other end 14b (base end) of one flexible tube base material 14 becomes the ratio of the thickness at one end 14a (tip end) of the next flexible tube base material 14. When molding the polymer coating layer 15 from one end 14a to the other end 14b of the next flexible tube base material 14, it is preferable that the extrusion units 21 and 22 are controlled in a similar manner so that the thickness of the outer layer gradually increases from one end to the other.

[0091] After the connecting flexible tube base material 31, which has the polymer coating layer 15 molded to the very end, is removed from the continuous molding machine 20, the joint member 30 is removed from the flexible tube base material 14 and the flexible tube base material 14 is separated. Next, a top coat layer 16 is coated onto the polymer coating layer 15 of the separated flexible tube base material 14 to complete the flexible tube 3a. The completed flexible tube 3a is then transported to the assembly process of the electronic endoscope.

[0092] In the present invention, if the polymer coating layer is a multilayer, a functional layer may be interposed between each of the layers constituting the multilayer. The above explanation uses an electronic endoscope, which uses an imaging device to capture images of a subject's condition and observes them, as an example, with reference to the drawings. However, the present invention is not limited to this and can also be applied to endoscopes that use optical image guidance to observe a subject's condition.

[0093] The flexible tube of the present invention can be widely applied to endoscopic medical devices. For example, it can be applied to instruments equipped with clips or wires at the tip of the endoscope, or instruments equipped with baskets or brushes. Note that "endoscopic medical devices" broadly includes not only medical devices with an endoscope as their basic structure as described above, but also medical or clinical devices such as remotely operated medical devices, which have a flexible insertion part and are introduced into the body for use. The endoscopic medical device of the present invention incorporates the flexible tube for endoscopes of the present invention into its insertion section. That is, the manufacturing method of the endoscopic medical device of the present invention includes incorporating the flexible tube for endoscopes of the present invention into the insertion section of the endoscopic medical device. [Examples]

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

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

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

[0097] <Formation of epoxy resin porous layer (L-1)> In a stainless steel container, 10.0 g of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, "jER828" (trade name), epoxy equivalent 184-194 g / eq.), 4.0 g of polyethylene glycol (Sanyo Chemical Industries, Ltd., "Sannix PEG-400" (trade name)), and 1950 g of methyl ethyl ketone were mixed to prepare an epoxy resin / polyethylene glycol methyl ethyl ketone solution. To this solution, 15.0 g of 1,6-diaminohexane was added, and the mixture was stirred at room temperature for 15 minutes using a three-one motor to obtain epoxy resin solution (D). The flexible tube substrate, after the above cleaning, 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. This flexible tube substrate was then heated in an oven at 100°C for 3 hours to form an epoxy resin layer on its outer surface. Next, the flexible tube substrate on which the epoxy resin layer was formed was ultrasonically cleaned for 10 minutes in a 1 / 1 (v / v) mixture of distilled water and dimethylformamide, then ultrasonically cleaned for 10 minutes with distilled water alone, and finally immersed in distilled water for 12 hours to remove the encapsulated polyethylene glycol. Subsequently, drying was performed at 80°C for 2 hours to form an epoxy resin porous layer (L-1) on the outer circumference of the flexible tube substrate.

[0098] <Formation of epoxy resin porous layers (L-2) to (L-9)> Except for using the components listed in Table 1 below, epoxy resin porous layers (L-2) to (L-9) were formed on the outer circumference of the flexible tube substrate in the same manner as the epoxy resin porous layer (L-1). That is, each flexible tube substrate having epoxy resin porous layers (L-2) to (L-9) on its outer circumference was 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, product name, manufactured by Nippon Colcoat Co., Ltd., 21% by mass solids, 2-propanol / ethanol / methanol solvent), 45 g of polyethylene glycol (Sanyo Chemical Industries, Ltd., Sannix PEG-400, product name), and 955 g of isopropyl alcohol were mixed to obtain silica composition (a). The flexible tube substrate, after the above cleaning, was immersed in silica composition (a) for 5 minutes, then removed and air-dried at 40°C for 30 minutes to evaporate the solvent. This flexible tube substrate was then heated in an oven at 100°C for 10 minutes to form a silica layer on its outer surface. Next, the flexible tube substrate on which the silica layer was formed was ultrasonically cleaned for 10 minutes in a 1 / 1 (v / v) mixture of distilled water and dimethylformamide, then ultrasonically cleaned for 10 minutes with distilled water alone, and finally immersed in distilled water for 12 hours to remove the encapsulated polyethylene glycol. Subsequently, drying was performed at 80°C for 2 hours to form a silica porous layer (L-10) on the outer circumference of the flexible tube substrate.

[0100] <Formation of silica porous layers (L-11)~(L-13)> Except for using the components listed in Table 2 below, silica porous layers (L-11) to (L-13) were formed on the outer circumference of the flexible tube substrate in the same manner as for the silica porous layer (L-10). That is, each flexible tube substrate having silica porous layers (L-11) to (L-13) on its outer circumference was obtained.

[0101] <Formation of epoxy nonporous layer (R-1)> In the formation of the epoxy porous layer (L-1) described above, a non-porous epoxy resin layer (R-1) was formed in the same manner as above, except that a nonionic surfactant was not used.

[0102] <Formation of the silica nonporous layer (R-2)> A silica layer without pores (R-2) was formed in the same manner as the silica porous layer (L-10) described above, except that polyethylene glycol was not used.

[0103] The average pore size, porosity, and average thickness of the porous layer were measured and calculated as follows. The measurement results are shown in Table 1 below. <Average pore diameter, porosity> Flexible tubes were used for the measurements after being placed in an oven set to 150°C for 4 hours and then allowed to stand in a desiccator until they reached room temperature. The measurements were performed using a mercury intrusion method with a porosimeter (Micromeritics "Pore Sizer 9320" (product name)). For the measurements, the initial pressure was 20 kPa, the measurement pore size was 3 nm to 400 μm, the measurement mode was a pressurized (intrusion) process, 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 prepared as described above was randomly cut at five locations, and each porous layer cross-section was observed at 50,000x magnification using a scanning electron microscope (S-5500 (product name), Hitachi High-Technologies Corporation). The thickness of the porous layer formed on the outer circumference was obtained at one point for each cross-section. The numerical average value was calculated from the five obtained values.

[0105] [Table 1]

[0106] [Table 2]

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

[0108] <Formation of the primer layer> 150g of ethanol, 350g of water, and 1.0g 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 solution for primer layer formation. A flexible tube substrate having a porous layer was immersed in the primer layer forming solution prepared above at room temperature for 1 minute, air-dried for 10 minutes, and then heated and dried in a 100°C oven for 10 minutes to prepare a flexible tube substrate having a primer layer on the porous layer (the flexible tube substrate used in Example 1). In the same manner as described above, flexible tube substrates for 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> A flexible tube substrate, with a primer layer on a porous layer, was extruded onto its outer circumference with polymers as described in Table 3 (Tables 3-1 and 3-2) below (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 cases where two polymer coating layers were used (Examples 1-36, 44-51, Comparative Examples 1-4, 6-8), 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 set to 80:20 at the front and 20:80 at the rear. The thickness of the inner and outer layers sloped from the front to the rear.

[0110] The following tests were performed on the fabricated flexible tubes. The results are summarized in Table 3 below.

[0111] [Test Example 1] Evaluation of the elasticity of a flexible tube Under conditions of 25°C and 50% relative humidity, the flexible endoscope tube prepared as described above was fixed at positions 30 cm and 50 cm from one end, and the 40 cm position (center of the flexible tube) was pushed 15 mm perpendicular to the length direction (diameter direction) of the flexible tube. The ratio of the rebound force at 30 seconds (b) to the rebound force at 0.1 seconds (a) was calculated as the elasticity (%). The rebound force was measured using a force gauge (ZTS50N (product name), manufactured by IMADA). [Resilience (%)] = [(b) / (a)] × 100 The above resilience was evaluated using the following criteria. A score of "C" or higher is considered passing. <Equilibrium Evaluation Criteria> A: Resilience is 80% or higher B: Resilience is between 75% and 80% C: Resilience is between 65% and 75% D: Resilience is less than 65%

[0112] [Test Example 2] Evaluation of bending durability (adhesion) of flexible pipes The flexible endoscope tube prepared above was placed in a U-shape on half of the circumference of a 7cm diameter pulley, and the tube was moved back and forth so that the tip and rear end came within 3.5cm of the pulley end. The condition of the polymer coating layer was then visually observed. The number of reciprocations required for the polymer coating layer to lift, tear, or peel was evaluated according to the following evaluation criteria. A score of "C" or higher is considered acceptable. <Bending durability evaluation criteria> A: More than 10,000 times B: 1,000 times or more but less than 10,000 times C: 100 times or more but less than 1,000 times D: Less than 100 times

[0113] [Test Example 3] Evaluation of the thermal cycling resistance of a flexible tube The flexible tube for endoscopes prepared as described above was subjected to a heat cycle test of 500 cycles using a constant temperature and humidity chamber (KHWV-40HP (product name) manufactured by Satake Chemical Machinery Industry Co., Ltd.), with one cycle consisting of 2 hours at 0°C and 2 hours at 60°C. After 500 heat cycles, the rebound force (c) of the flexible tube for endoscopes was measured 0.1 seconds after being pressed in, in the same manner as in Test Example 1. The ratio of the rebound force (c) to the rebound force (a) measured before the heat cycle test in the same manner as in Test Example 1 was calculated as the rebound force maintenance rate (%). [Percentage of rebound force maintenance (%)] = [(c) / (a)] × 100 The rebound force maintenance rate described above was evaluated using the following evaluation criteria. A score of "C" or higher is considered a passing grade. <Thermal Cycle Performance Evaluation Criteria> A: Rebound force maintenance rate is 90% or higher B: Rebound force maintenance rate is 70% or more but less than 90% C: Rebound force maintenance rate is 50% or more but less than 70% D: Rebound force maintenance rate is less than 50%

[0114] [Table 3-1]

[0115] [Table 3-2]

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

[0117] Actual: Example Comparison: Comparative Example

[0118] (Silane coupling agent) (S-1): N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (product 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-Uleidopropyltrialkoxysilane (Trade name: KBE-585, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-5): N-phenyl-3-aminopropyltrimethoxysilane (product name: KBM-573, manufactured by Shin-Etsu Chemical Co., Ltd.) (S-6): 3-Trimethoxysilylpropyl succinic 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 Chemical Co., Ltd.) (A-2): Aluminum trisacetylacetonate (product name: Orgatics AL-3100, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-3): Aluminum bisethyl acetoacetate monoacetylacetonate (product name: Orgatics AL-3200, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-4): Aluminum trisethyl acetoacetate (product name: Orgatics AL-3215, manufactured by Matsumoto Fine Chemical Co., Ltd.) (A-5): Aluminum octadecylacetoacetate diisopropylate (product name: PrenAct AL-M, manufactured by Ajinomoto Fine Techno Co., Ltd.)

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

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

[0122] (U-1): Polyether polyurethane elastomer (product name: Pandex T-8185, manufactured by DIC Corporation) (U-2): Polyether polyurethane elastomer (product name: Miractran E380, manufactured by Nippon Polyurethane Co., Ltd.) (U-3): Polyester polyurethane elastomer (product name: Miractran 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: Perprene P-40B, manufactured by Toyobo Co., Ltd.) (Ae-1): Polyamide elastomer (product 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 following can be seen from the table above. The flexible tubes of Comparative Examples 1 and 6-8, which do not have the porous layer defined in the present invention, exhibit poor adhesion and heat resistance even when 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, its adhesion and heat resistance are poor. Similarly, the flexible tube of Comparative Example 3, which has a non-porous silica layer between the flexible tube substrate and the primer layer, 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 lacks a primer layer as defined in the present invention. This flexible tube has poor adhesion and heat resistance. The flexible tube of Comparative Example 5 has a fluorine-containing elastomer layer as a polymer coating layer. That is, it does not have the polymer coating layer defined in the present invention. This flexible tube is inferior in elasticity, adhesion, and heat resistance. In contrast, the flexible tubes of the present invention described in Examples 1 to 51 possess sufficient elasticity, excellent adhesion, and also excellent heat resistance. [Explanation of symbols]

[0124] 2. Electronic endoscope (endoscope) 3 Insertion part 3a flexible tube 3b Angle section 3c Tip 5. Main Unit Control Panel 6 Universal Code 11 Spiral tube 11a metal strip 12. Tubular mesh 13 nozzles 14 Flexible tube base material 14a Tip side 14b Proximal end 15 Polymer coating layer 16. Top coat layer 17 Inner Layer 18 Outer layer X-angle section 3b side (soft) Y Main unit control panel 5 side (hard) 20. Continuous molding machine (manufacturing equipment) 21, 22 Extrusion section 21a Screw 22a Screw 23 Head section 24 Cooling section 25 Conveying section 26 Control Unit 28 supply drums 29 Reel Drum 30 Joint members 31 Connected flexible tube base material 32 Nipples 33 dice 34 Support Gates 35 and 36 37 Molding passage 38 Polymer passage 39. First Polymer Material (Flexible Polymer) 40. Second Polymer Material (Hard Polymer)

Claims

1. The flexible tube substrate comprises a metal as a constituent material, a porous layer on the flexible tube substrate, a primer layer on the porous layer, and a polymer coating layer on the primer layer. The porous layer is a polymer compound layer with a porous structure containing at least one of an epoxy resin crosslinker and a siloxane, and the average pore size of the porous layer is 50 nm to 100 μm. The primer layer comprises at least one of a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent. A flexible tube for an endoscope, wherein the polymer coating layer contains at least one compound of polyamide, polyester, polyurethane, and polyolefin on the side in contact with the primer layer.

2. The flexible tube for endoscopes according to claim 1, wherein the primer layer contains a silane coupling agent.

3. The flexible tube for endoscopes according to claim 1 or 2, wherein the primer layer contains an aminosilane coupling agent.

4. The flexible tube for endoscope according to any one of claims 1 to 3, wherein the thickness of the primer layer is 1 nm or more and 100 nm or less.

5. The flexible tube for endoscopes according to any one of claims 1 to 4, wherein the metal constituting the flexible tube base material is stainless steel.

6. The flexible tube for endoscope according to any one of claims 1 to 5, wherein the metal constituting the flexible tube base material has a passivation film on its surface.

7. The flexible tube for endoscopes according to any one of claims 1 to 6, wherein the polymer coating layer has a single-layer or multi-layer structure, and the layer in contact with the primer layer contains at least one compound of polyamide, polyester, polyurethane, and polyolefin.

8. The flexible tube for endoscope according to any one of claims 1 to 7, wherein the polymer coating layer has a two-layer structure, and the ratio of the thicknesses of the inner and outer layers of the two-layer structure changes in a gradual manner in the axial direction of the flexible tube base material.

9. The endoscopic flexible tube according to claim 8, wherein the ratio of the thicknesses of the inner layer and the outer layer is 95:5 to 60:40 at one end of the endoscopic flexible tube and 5:95 to 40:60 at the other end.

10. An endoscopic medical device having a flexible tube for endoscopy as described in any one of claims 1 to 9.

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