Flexible tubes for endoscopes and their manufacturing methods, endoscopic medical devices, and manufacturing methods of covering materials.

Abstract

This invention discloses a flexible tube for endoscopes, an endoscopic medical device having the flexible tube for endoscopes, a method for manufacturing a coating material constituting the flexible tube for endoscopes, and a method for manufacturing the flexible tube for endoscopes. The flexible tube for endoscopes has a cylindrical flexible tube substrate and a polyester elastomer layer. The flexible tube substrate is flexible, and the polyester elastomer layer covers the flexible tube substrate and has a naphthalene structure in the soft chain segment.

Description

Technical Field

[0001] This invention relates to flexible tubes for endoscopes, endoscopic medical devices, a method for manufacturing a coating material constituting a flexible tube for endoscopes, and a method for manufacturing a flexible tube for endoscopes. Background Technology

[0002] An endoscope is a medical instrument used to observe the inside of a patient's body cavities, digestive tract, or esophagus. Because it is inserted into the body, it is desirable to avoid damaging organs and to minimize pain and / or discomfort for the patient. Considering these requirements, the flexible tube constituting the insertion part of the endoscope is a spiral tube formed by spirally winding a soft, bent metal strip. Furthermore, it is surrounded by a soft resin coating to prevent irritation or damage to the inner surfaces of the esophagus, digestive tract, or body cavities.

[0003] Endoscopes used for observing the human body are reused. Therefore, the flexible tube that forms the insertion part of the endoscope needs to be cleaned and sterilized with chemicals after each use. Especially when inserted into high-risk sites such as the bronchus, a level of cleanliness exceeding that of sterilization is required. Therefore, the flexible tube for endoscopes must possess a high degree of durability that can withstand repeated sterilization processes.

[0004] For example, Patent Document 1 describes a resin layer used as the constituent material of the flexible tube substrate, which uses 10% thermoplastic resin with a tensile strength of 10 MPa or more, and mixes hindered amine compounds with a molecular weight of 500 or more into the resin. As a result, the resin layer is not prone to deterioration regardless of repeated hydrogen peroxide plasma treatment or repeated hydrogen peroxide gas treatment.

[0005] In addition, Patent Document 2 describes a flexible tube for endoscopes, which is formed by covering the surface of a flexible tube with an outer skin. In this case, by using polybutylene naphthalene dicarboxylate in the hard segments of the polyester elastomer constituting the outer skin, the deterioration of the outer skin caused by cleaning solution or disinfectant can be suppressed.

[0006] In addition, Patent Document 3 describes an endoscope flexible tube covered with an outer skin made of an endoscope elastomer molded body made of two or more thermoplastic polyester elastomers crosslinked together, which is less prone to outer skin deterioration for various drugs.

[0007] Previous technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2019 / 189035

[0010] Patent Document 2: Japanese Patent Application Publication No. 2004-141487

[0011] Patent Document 3: Japanese Patent Application Publication No. 2009-183467 Summary of the Invention

[0012] The technical problem to be solved by the invention

[0013] Regarding the sterilization durability of flexible endoscope tubes, sterilization treatment using ozone water, prepared by dissolving trace amounts of ozone (O3) in water, has recently begun. However, this ozone water generates highly reactive species such as hydroxyl radicals, whose oxidizing power is stronger than that of hydrogen peroxide gas. Therefore, as an organic material for ozone water sterilization treatment, fluoropolymers are currently the known option.

[0014] Furthermore, flexible tubes suitable for use in narrow tubes such as the bronchi require a sufficiently small diameter. As the diameter of the flexible tube decreases, the operability of the flexible tube from the endoscope's manipulator decreases. For example, when inserting a flexible tube into a bronchus, the tube is inserted in a bent position along the branching structure of the bronchus. In this position, when the manipulator is pushed in or rotated, the physical changes in the manipulator are sometimes not adequately transmitted to the tip of the inserted flexible tube. In such cases, it may be difficult to perform appropriate clinical examinations or procedures.

[0015] In view of the above, an object of the present invention is to provide a flexible endoscope tube and an endoscopic medical device using the flexible endoscope tube, wherein the flexible endoscope tube can fully and effectively transmit the movements of the endoscope operating part to the tip of the flexible tube, and exhibits excellent sterilization durability against strong sterilization treatments such as ozone water. Furthermore, an object of the present invention is also to provide a method for manufacturing the coating material constituting the aforementioned flexible endoscope tube and a method for manufacturing the aforementioned flexible endoscope tube.

[0016] means for solving technical problems

[0017] The inventors have conducted in-depth research on the above-mentioned problems and have found that, as a constituent material of the outer sheath of the flexible tube for endoscopes, the above-mentioned problems can be solved by using a polyester elastomer in which a naphthalene structure is assembled in the soft chain segment, thus completing the present invention.

[0018] The above objectives can be achieved through the following methods.

[0019] <1>

[0020] An endoscope flexible tube has a cylindrical flexible tube substrate and a polyester elastomer layer, wherein the flexible tube substrate is flexible and the polyester elastomer layer covers the flexible tube substrate.

[0021] The aforementioned polyester elastomer has a naphthalene structure in its soft chain segment.

[0022] <2>

[0023] according to <1> The flexible tube for the endoscope, wherein,

[0024] The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components constituting the above-mentioned soft chain segment is 2 to 100 mol%.

[0025] <3>

[0026] according to <1> or <2> The flexible tube for the endoscope, wherein,

[0027] The aforementioned polyester elastomer has a naphthalene structure in its hard chain segment.

[0028] <4>

[0029] according to <3> The document describes the use of flexible tubes in endoscopes, among which...

[0030] The aforementioned hard segments contain naphthalene dicarboxylic acid and phthalic acid.

[0031] <5>

[0032] according to <4> The document describes the use of flexible tubes in endoscopes, among which...

[0033] At least a portion of the phthalic acid component mentioned above is isophthalic acid component.

[0034] <6>

[0035] according to <3> ~ <5> The flexible tube for the endoscope described in any one of the following statements, wherein,

[0036] The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components constituting the above-mentioned hard chain segment is 5–90 mol%.

[0037] <7>

[0038] according to <4> ~ <6> The flexible tube for the endoscope described in any one of the following statements, wherein,

[0039] Phthalic acid accounts for 10–95 mol% of all dicarboxylic acid components constituting the above-mentioned hard segments.

[0040] <8>

[0041] according to <5> ~ <7> The flexible tube for the endoscope described in any one of the following statements, wherein,

[0042] The proportion of isophthalic acid in all dicarboxylic acid components constituting the above-mentioned hard segment is 10 to 40 mol%.

[0043] <9>

[0044] according to <1> ~ <8> The flexible tube for the endoscope described in any one of the following statements, wherein,

[0045] The number-average molecular weight of the aforementioned soft segments is greater than 10,000 and less than 21,000.

[0046] <10>

[0047] An endoscopic medical device, wherein,

[0048] have <1> ~ <9> The flexible tube for endoscopes as described in any one of these descriptions.

[0049] <11>

[0050] A method for manufacturing a coating material constituting a flexible tube for an endoscope, wherein the manufacturing method includes:

[0051] A process for obtaining a polyester compound by esterifying a polyalkylene glycol, which is a diol compound and has a number average molecular weight of 1,000 or more, and at least naphthalene dicarboxylic acid, which is a dicarboxylic acid compound; and

[0052] The process of esterifying the above-mentioned polyester compound, a diol compound with a molecular weight of less than 500 and a dicarboxylic acid compound to obtain a polyester elastomer having the above-mentioned polyester compound as a soft segment.

[0053] <12>

[0054] A method for manufacturing a flexible tube for an endoscope, comprising:

[0055] Use via <11> The coating material obtained by the manufacturing method is used to coat the flexible tube substrate.

[0056] Invention Effects

[0057] The flexible endoscope tube of the present invention can fully and effectively transmit the movements of the endoscope operating part to the tip of the flexible tube, and exhibits excellent sterilization durability against strong sterilization treatments such as ozone water. The endoscopic medical device of the present invention is an instrument possessing an endoscopic flexible tube having the above-mentioned excellent characteristics. Furthermore, according to the method for manufacturing the coating material constituting the endoscopic flexible tube of the present invention, a coating material exhibiting the above-mentioned characteristics can be obtained. According to the method for manufacturing the endoscopic flexible tube of the present invention, an endoscopic flexible tube of the present invention having the above-mentioned characteristics can be obtained. Attached Figure Description

[0058] Figure 1 This is an external diagram showing the structure of an electronic endoscope.

[0059] Figure 2 This is a partial cross-sectional view illustrating the schematic structure of a flexible tube for endoscopy. Detailed Implementation

[0060] A preferred embodiment of the endoscopic medical device of the present invention will be described using an electronic endoscope as an example. An endoscopic flexible tube (hereinafter, sometimes simply referred to as a "flexible tube") is assembled in the electronic endoscope, and this flexible tube is inserted into a body cavity, digestive tract, esophagus, etc., for use as a medical device for observing the body internally. Figure 1 In the example shown, the electronic endoscope 2 includes an insertion part 3 for insertion into the body, a main operating part 5 connected to the base of the insertion part 3, and a universal plug 6 connected to a processor or light source device. The insertion part 3 consists of a flexible tube 3a connected to the main operating part 5, a bend 3b connected to the flexible tube 3a, and a tip part 3c connected to the front end of the bend 3b and housing an in-vivo imaging device (not shown). The flexible tube 3a, which occupies most of the length of the insertion part 3, is flexible almost along its entire length, and the portion inserted into the esophagus, digestive tract, or body cavity is particularly flexible.

[0061] Flexible tube

[0062] like Figure 2 As shown, the flexible tube 3a (flexible tube for endoscope) is configured to have a flexible tube substrate 14, which is formed by covering a cylindrical mesh 12 made of woven metal wire onto a spiral tube 11 formed by winding a metal strip 11a into a spiral shape on the innermost side, and fitting tube heads 13 at both ends. Furthermore, a polyester elastomer layer 15 is coated on the outer peripheral surface of the flexible tube substrate 14. Only one layer of the spiral tube 11 is shown, but it can also be configured as two coaxially overlapping layers. Moreover, to clearly illustrate the layer structure, the polyester elastomer layer 15 is depicted as being thicker than the wall of the flexible tube substrate 14.

[0063] In this embodiment, the polyester elastomer layer 15 is formed with a substantially uniform thickness along the longitudinal direction (axial direction) of the flexible tube substrate 14. The thickness of the polyester elastomer layer 15 is, for example, 0.1 to 0.6 mm. The outer diameter D of the flexible tube 3a is, for example, 2.0 to 10.0 mm, preferably 3.0 to 8.0 mm. Furthermore, the outer diameter of the flexible tube substrate 14 is, for example, 1.6 to 9.6 mm, preferably 2.2 to 7.8 mm. In the case of a small endoscope assuming the insertion part 3 is inserted into a bronchus, the thickness of the polyester elastomer layer 15 is preferably 0.1 to 0.3 mm. In this case, the outer diameter D of the flexible tube 3a is preferably 3.0 to 5.0 mm, and the outer diameter of the flexible tube substrate 14 is preferably 2.4 to 4.8 mm.

[0064] The flexible tube of the present invention has a cylindrical flexible tube substrate and a polyester elastomer layer 15 covering the flexible tube substrate, the flexible tube substrate being flexible.

[0065] The polyester elastomer layer 15 can be a single layer or a multilayer composed of layers with different compositions (multilayers with different ratios of dicarboxylic acid components or diol components). The polyester elastomer layer 15 is preferably a single layer.

[0066] Alternatively, the flexible tube of the present invention may also have a surface coating on the outer side of the polyester elastomer layer 15. For example, the composition of the surface coating can be described in Japanese Patent Application Publication No. 2015-16261.

[0067] <Polyester Elastomers>

[0068] The polyester elastomer layer 15 is a layer with a specific structure of polyester elastomer as the main constituent material, as described later.

[0069] The polyester elastomer constituting the polyester elastomer layer 15 (hereinafter referred to as "the polyester elastomer used in this invention") is a block copolymer composed of soft segments and hard segments, wherein the soft segments are composed of polyester chains having a naphthalene structure and the hard segments are composed of a crystalline polyester structure.

[0070] The polyester constituting the above-mentioned soft segments preferably contains naphthalene dicarboxylic acid as a dicarboxylic acid component and polymer diol as a diol component.

[0071] The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components (100 mol%) constituting the above-mentioned soft segment is preferably 2 to 100 mol%, more preferably 4 to 100 mol%, further preferably 10 to 100 mol%, particularly preferably 20 to 100 mol%, even more preferably 50 to 100 mol%, and most preferably 60 to 100 mol%. It is also preferred that all dicarboxylic acid components constituting the soft segment are naphthalene dicarboxylic acid.

[0072] In this invention, 2,6-naphthalenedicarboxylic acid is listed as an example of a naphthalenedicarboxylic acid component.

[0073] In the case where the soft segment contains dicarboxylic acid components other than naphthalene dicarboxylic acid, there are no particular limitations on the dicarboxylic acid components, and dicarboxylic acid components commonly used in polyester compounds can be widely used. For example, components derived from phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanoic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesocarboxylic acid, cyclohexanedicarboxylic acid, etc., can be used. That is, the soft segment may have one or more constituent components derived from these exemplified dicarboxylic acids.

[0074] The soft segment preferably contains phthalic acid, more preferably contains at least one of terephthalic acid and isophthalic acid, and even more preferably contains terephthalic acid.

[0075] The polymer diol component constituting the aforementioned soft segment preferably has a number average molecular weight of 1,000 or more, more preferably 1,200 or more, and even more preferably 1,500 or more. Furthermore, the number average molecular weight of the aforementioned polymer diol component is preferably 10,000 or less, more preferably 6,000 or less, and even more preferably 4,000 or less. The aforementioned soft segment may also contain diol components other than the polymer diol component (low molecular weight diol compounds) without impairing the effects of the present invention, but typically the diol component of the aforementioned soft segment is composed of a polymer diol component.

[0076] Preferred examples of the aforementioned polymer glycol components include polyethylene glycol, polypropylene glycol, and polytetramethylene oxide glycol (polytetramethylene ether glycol), which are derived from polyalkylene glycols. In this invention, the polyalkylene glycol is prepared using HO-[(CH2)]... m O] n The compound is represented by -H. Here, m is preferably 1 to 12, more preferably 2 to 10, even more preferably 2 to 8, and particularly preferably 2 to 6. In addition, n is preferably 5 to 100, more preferably 10 to 50.

[0077] The molecular weight of the aforementioned soft segments can be appropriately set within a range that does not impair the effects of the present invention. For example, the number-average molecular weight can be set to 5,000 or more, preferably 10,000 or more and less than 21,000, more preferably 10,000 to 20,000, further preferably 11,000 to 18,000, and particularly preferably 11,000 to 16,000.

[0078] In this invention, the number-average molecular weight of the soft segments and the weight-average molecular weight of the polymer are determined by gel permeation chromatography with RI detection at 23°C and a flow rate of 1 mL / min using chloroform as the eluent and G3000HXL+G2000HXL (both trade names, manufactured by Tosoh Corporation) as the chromatographic column. (Conversion value for standard polystyrene)

[0079] The soft chain segments constituting the above-mentioned polyester elastomer preferably comprise 10 to 90% by mass, more preferably 20 to 80% by mass, and even more preferably 25 to 75% by mass.

[0080] The structure of the aforementioned hard segments is not particularly limited as long as they function as hard segments in the polyester elastomer. From the viewpoint of improving the operability of flexible tubes, hard segments preferably have a naphthalene structure.

[0081] The aforementioned hard segments are composed of dicarboxylic acid and diol components. These hard segments may also contain hydroxycarboxylic acid components.

[0082] There are no particular limitations on the dicarboxylic acid component constituting the hard segment described above; dicarboxylic acid components commonly used in the hard segments of polyester elastomers can be widely used. The molecular weight of the dicarboxylic acid component constituting the hard segment is preferably 400 or less. For example, the dicarboxylic acid component can be derived from phthalic acid, naphthalene dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanoic acid, dimer acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesocarboxylic acid, cyclohexane dicarboxylic acid, etc. That is, the hard segment may have one or more constituent components from these exemplified dicarboxylic acid compounds. The dicarboxylic acid component constituting the hard segment preferably contains an aromatic dicarboxylic acid component (a dicarboxylic acid component having an aromatic ring), and 50% or more (preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more) of the dicarboxylic acid component constituting the hard segment is preferably an aromatic dicarboxylic acid component. Furthermore, it is also preferable that all the dicarboxylic acid components constituting the hard segment are aromatic dicarboxylic acids.

[0083] In particular, the aforementioned hard segment preferably contains at least one of phthalic acid and naphthalenedicarboxylic acid. When the hard segment contains phthalic acid, it is more preferably containing at least one of terephthalic acid and isophthalic acid. The dicarboxylic acid component constituting the hard segment more preferably contains both naphthalenedicarboxylic acid and phthalic acid (at least one of terephthalic acid and isophthalic acid), and from the viewpoint of operability of the flexible tube, it is more preferable that at least a portion of the aforementioned phthalic acid component is isophthalic acid. That is, from the viewpoint of operability of the flexible tube, the aforementioned hard segment further preferably contains both naphthalenedicarboxylic acid and isophthalic acid.

[0084] When the aforementioned hard segment contains naphthalene dicarboxylic acid, all dicarboxylic acid components constituting the aforementioned hard segment may also be naphthalene dicarboxylic acid. The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components (100 mol%) constituting the aforementioned hard segment is preferably 5 to 90 mol%, and more preferably 10 to 80 mol%.

[0085] Furthermore, when the aforementioned hard segment contains phthalic acid, all dicarboxylic acid components constituting the hard segment may also be phthalic acid. The proportion of phthalic acid in all dicarboxylic acid components constituting the hard segment is preferably 10-95 mol%, more preferably 20-90 mol%. The proportion of isophthalic acid in the hard segment is preferably 10-40 mol%, more preferably 15-30 mol%.

[0086] There are no particular limitations on the diol composition constituting the hard segment described above; diol compositions commonly used in the hard segments of polyester elastomers can be widely used. The molecular weight of the diol composition constituting the hard segment is preferably 500 or less. The diol composition can be, for example, derived from ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanediol, triethylene glycol, bisphenol A, bisphenol S, etc. That is, the hard segment may have one or more constituent components derived from these exemplified diol compounds.

[0087] In particular, the aforementioned hard segments preferably contain at least one of ethylene glycol, diethylene glycol, 1,3-propanediol, and 1,4-butanediol, more preferably at least one of ethylene glycol, 1,3-propanediol, and 1,4-butanediol, and even more preferably 1,4-butanediol.

[0088] When the above-mentioned hard segment contains a hydroxycarboxylic acid component, it can be a component derived from 6-hydroxyhexanoic acid, lactic acid, 4-hydroxybenzoic acid, etc.

[0089] The aforementioned hard segments can be homopolymers or copolymers composed of the aforementioned components.

[0090] The molecular weight of the polyester elastomer used in this invention is not particularly limited. For example, the weight-average molecular weight can be set to 10,000 to 300,000, and is usually 20,000 to 100,000.

[0091] The polyester elastomer used in this invention can be obtained by mixing the polyester chain constituting the soft segment with a dicarboxylic acid compound, a diol compound, or the like, which are raw materials for the hard segment, after forming the polyester chain, and then subjecting it to a polycondensation reaction. For example, the polyester elastomer used in this invention can be obtained through the following steps.

[0092] A process for obtaining a polyester compound by esterifying a polyalkylene glycol, which is a diol compound and has a number average molecular weight of 1,000 or more, and at least naphthalene dicarboxylic acid, which is a dicarboxylic acid compound; and

[0093] A process of esterifying the polyester compound, a diol compound with a molecular weight of 500 or less, and a dicarboxylic acid compound (preferably with a molecular weight of 400 or less) obtained in the above process to obtain a polyester elastomer having the above polyester compound as a soft segment.

[0094] A polyester elastomer layer 15 can be formed by, for example, extruding the polyester elastomer used in this invention onto the outer periphery of the flexible tube substrate 14. The polyester elastomer layer 15 can be formed from the polyester elastomer used in this invention, or it can be formed by mixing the polyester elastomer used in this invention with other resins or elastomers without impairing the effects of this invention. Additionally, the polyester elastomer layer 15 can be formed by mixing plasticizers, light stabilizers, lubricants, antistatic agents, mold release agents, colorants (e.g., pigments and dyes), antioxidants, light stabilizers, etc., as needed.

[0095] The content of the polyester elastomer used in the present invention in the polyester elastomer layer 15 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.

[0096] To improve the adhesion between the flexible tube substrate 14 and the aforementioned polyester elastomer layer 15, an adhesive layer, a primer layer, or the like can be provided between them. As an example of such an adhesive layer, an adhesive layer formed from a composition of a polymer such as polyurethane and a polyisocyanate compound can be cited. Furthermore, as a primer layer, a silane coupling agent can be cited.

[0097] The flexible tube of the present invention has the aforementioned polyester elastomer layer 15, which can effectively transmit physical changes from the endoscope operating section to the tip of the flexible endoscope tube. Although the reason is not yet certain, it is believed that the rigid structure of the naphthalene structure in the soft segments constituting the polyester elastomer contributes to the effective transmission of physical changes. Furthermore, it is believed that when the hard segments of the polyester elastomer have a naphthalene structure and contain isophthalic acid, the elasticity of the polyester elastomer is improved due to the isophthalic acid component, further improving the operability of the flexible endoscope tube of the present invention.

[0098] Furthermore, the flexible tube of the present invention also exhibits high sterilization durability under intensive sterilization treatment with ozone water. This is believed to be because the soft segments of the aforementioned polyester elastomer have a naphthalene structure with a large molecular area, which effectively hinders the migration and even penetration of active species such as hydroxyl radicals into the aforementioned polyester elastomer layer 15.

[0099] <Manufacturing Method of Coating Material Constituting Flexible Tube for Endoscopes>

[0100] The coating material constituting the flexible endoscope tube of the present invention (hereinafter also referred to as "the coating material of the present invention") is the forming material of the coating layer of the flexible tube substrate. That is, the method for manufacturing the coating material of the present invention includes a step of manufacturing the polyester elastomer used in the present invention as described above, and preferably includes a step of obtaining the polyester elastomer through the steps described below.

[0101] A process for obtaining a polyester compound by esterifying a polyalkylene glycol, which is a diol compound and has a number average molecular weight of 1,000 or more, and at least naphthalene dicarboxylic acid, which is a dicarboxylic acid compound; and

[0102] The process of esterifying the polyester compound, a diol compound with a molecular weight of less than 500, and a dicarboxylic acid compound (preferably with a molecular weight of less than 400) to obtain a polyester elastomer having the polyester compound as a soft segment.

[0103] The method for manufacturing the coating material of the present invention may also include a step of mixing the polyester elastomer obtained above with other materials (resin, elastomer, additives, etc.) constituting the polyester elastomer layer 15.

[0104] <Manufacturing Method of Flexible Tubes for Endoscopes>

[0105] By coating a flexible tube substrate with the coating material obtained by the above-described method for manufacturing the coating material, a flexible tube for endoscopes can be obtained. Extrusion coating is preferably used as the coating method for the flexible tube substrate. Furthermore, as described above, an adhesive layer or a primer layer may be provided on the surface of the flexible tube substrate before coating with the coating material.

[0106] Endoscopic medical devices

[0107] The flexible tube for endoscopes involved in this invention is not limited to endoscope applications and can be widely used in endoscopic medical devices. For example, it can also be used in devices with clamps or wires attached to the tip of an endoscope, or devices with baskets or brushes attached, achieving excellent results. Furthermore, endoscopic medical devices refer not only to medical devices with the endoscope as their basic structure, but also broadly include flexible medical or diagnostic instruments that are inserted into the body, such as remotely operated medical devices.

[0108] [Example]

[0109] The present invention will now be described in further detail through embodiments, but the interpretation of the present invention is not limited thereto.

[0110] (Example 1)

[0111] <Preparation of Polyester Elastomers>

[0112] 5.1 parts by weight of terephthalic acid, 0.3 parts by weight of 2,6-naphthalenedicarboxylic acid, and 64.6 parts by weight of polytetramethylene glycol (PTMG) with a number average molecular weight of 2,000 were placed in a reaction vessel equipped with a spiral ribbon stirrer. Esterification was carried out using 0.3 parts by weight of tetrabutoxytitanium catalyst, followed by the addition of 0.1 parts by weight of dibutyltin diacetate catalyst. Polycondensation was then performed under reduced pressure to obtain an amorphous soft-segment polyester (S-1). The molar ratios of the components of this soft segment are shown in the table below.

[0113] To 70 parts by weight of this polyester (S-1), 19.5 parts by weight of terephthalic acid and 10.5 parts by weight of 1,4-butanediol (1,4-BD) were added, and the mixture was stirred at 225–245 °C and 130 Pa for 1 hour. After confirming that the polymer became transparent, 0.26 parts by weight of phenylphosphonic acid was added to stop the reaction, yielding a polyester elastomer composed of soft and hard segments. The molar ratio of terephthalic acid to 1,4-butanediol used for the formation of the hard segment is also shown in the table below.

[0114] <Polymer Molecular Weight Determination>

[0115] The number-average molecular weight of the soft segments and the weight-average molecular weight of the polyester elastomer (converted to standard polystyrene values) were determined by gel permeation chromatography (GPC) with RI detection using a GLC-8220 GPC apparatus (manufactured by Tosoh Corporation), with chloroform as the eluent and a G3000HXL+G2000HXL column at 23°C and a flow rate of 1 mL / min. The results are shown in Table 1.

[0116] Fabrication of Flexible Tube Substrates

[0117] A spiral tube 11 is formed using stainless steel metal strips 11a, and a flexible tube substrate in the form of the spiral tube 11 is prepared to be covered with a tubular mesh 12 incorporating stainless steel fibers. The flexible tube substrate is 80 cm in length and 12 mm in diameter. The stainless steel flexible tube substrate has a passivation layer formed on its surface through an annealing treatment (heat treatment) during the formation of the spiral tube and the tubular mesh.

[0118] <Formation of the adhesive layer>

[0119] An adhesive layer forming solution prepared by mixing 10 parts by weight of polyester polyurethane ("N-2304" manufactured by Nippon Polyurethane Co., Ltd.), 1 part by weight of polyisocyanate ("curing agent L" manufactured by Nippon Polyurethane Co., Ltd.), and 20 parts by weight of methyl ethyl ketone was uniformly coated on the outer periphery of the aforementioned stainless steel flexible tube substrate and dried at room temperature for two hours. Subsequently, it was further heat-treated at 150°C for two hours to prepare a flexible tube substrate with an adhesive layer on the outer periphery (the surface covered by the polyester elastomer layer).

[0120] <Formation of Polyester Elastomer Layer>

[0121] The aforementioned polyester elastomer is extruded and coated onto the outer periphery of a flexible tube substrate having an adhesive layer (molding temperature: 220°C), thus fabricating an endoscope flexible tube having a polyester elastomer layer on the outer periphery of the flexible tube substrate. The thickness of the resin coating layer is 0.4 mm.

[0122] (Examples 2-20, Comparative Examples 1-2)

[0123] Except for the changes in the dicarboxylic acid and diol components constituting the soft and hard segments as shown in Tables 1 to 3, the flexible tube for endoscopy was fabricated in the same manner as in Example 1.

[0124] [Experimental Example 1] Evaluation of the operability of flexible tubes

[0125] The endoscope fabricated above was bent into a U-shape along a circle with a diameter of 30 cm using a flexible tube, and fixed within this shape. In this fixed state, the flexible tube's following motion to twist is not restricted.

[0126] With the U-shaped fixed position, a 180° input angle (i.e., a 180° twist at an angular velocity of 180° / second) is applied to one end of the flexible tube, and the output angle is read after 5 seconds from the goniometer mounted on the other end. The obtained output angle is evaluated against the following evaluation criteria. A larger output angle means that the movement of the endoscope manipulation unit can be more effectively transmitted to the tip of the flexible tube, resulting in excellent operability as a flexible tube for endoscopes.

[0127] <Operability Evaluation Criteria>

[0128] AA: Output angle is 150° or higher

[0129] A: Output angle is 120° or higher and less than 150°

[0130] B: Output angle is 90° or higher and less than 120°

[0131] C: Output angle is 45° or higher and less than 90°

[0132] D: Output angle less than 45°

[0133] [Experimental Example 2] Evaluation of Ozone Water Tolerance

[0134] The polyester elastomer layer was peeled off from the aforementioned flexible endoscope tube, and a 1cm × 10cm test piece was cut from it. This test piece was placed in the flow path of an ozone water generator (trade name: OWM-10L10P, manufactured by Ecodesign Corporation), and ozone water with an ozone concentration of 3 ppm was allowed to flow at a rate of 1 L / min for 3 hours. Afterwards, the piece was rinsed with distilled water and dried at 23°C × 50% RH (relative humidity) for 24 hours. Subsequently, a tensile test was performed using a TENSILON universal testing machine (trade name: RTF-1210, manufactured by A&D Corporation), and evaluated against the following evaluation criteria (100% elongation means elongation to twice its original length).

[0135] <Ozone Water Tolerance Evaluation Criteria>

[0136] A: It did not break even when the elongation reached 300%.

[0137] B: It did not break even when the elongation reached 200%, but broke before the elongation reached 300%.

[0138] C: It did not break even when the elongation reached 100%, but broke before the elongation reached 200%.

[0139] D: It breaks before the elongation reaches 100%.

[0140] [Table 1]

[0141]

[0142] [Table 2]

[0143]

[0144] [Table 3]

[0145]

[0146] In Tables 1 to 3, S / H represents the ratio (by mass) of the content of soft segments to the content of hard segments in the polyester elastomer.

[0147] According to Tables 1 to 3, the following results can be obtained: Regardless of whether there is a naphthalene structure in the hard chain segment, when using a flexible tube substrate coated with a polyester elastomer that does not have a naphthalene structure in the soft chain segment, the operability of the flexible tube for endoscope is poor, and the ozone water resistance is also poor (Comparative Examples 1 and 2).

[0148] In contrast, when using a flexible tube substrate coated with a polyester elastomer incorporating a naphthalene structure in the soft chain segment, the operability of the flexible tube for endoscopes can be improved regardless of whether the hard chain segment of the polyester elastomer contains a naphthalene structure, and ozone water resistance can also be effectively improved (Examples 1-20).

[0149] The invention has been described together with its embodiments, but we believe that, unless otherwise specified, our invention should not be limited to any of the details described, and should be interpreted broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0150] This application claims priority based on Japanese Patent Application No. 2020-111753, filed on June 29, 2020, the contents of which are incorporated herein by reference and incorporated herein by reference as part of the description.

[0151] Symbol Explanation

[0152] 2. Electronic endoscope (endoscope)

[0153] 3. Insertion section

[0154] 3a Flexible tube

[0155] 3b Corner

[0156] 3C top part

[0157] 5 Main Operating Unit

[0158] 6. Universal Rope

[0159] 11. Spiral tube

[0160] 11a Metal strip

[0161] 12 cylindrical mesh

[0162] 13 Pipe head

[0163] 14 Flexible tube substrate

[0164] 15 Polyester elastomer layer

Claims

1. A flexible tube for an endoscope, comprising a cylindrical flexible tube substrate and a polyester elastomer layer, wherein the flexible tube substrate is flexible, and the polyester elastomer layer covers the flexible tube substrate, wherein... The polyester elastomer has a naphthalene structure in the soft chain segment and a structure derived from a polymeric diol component with a number average molecular weight of 1,000 or more.

2. The flexible endoscope tube according to claim 1, wherein, The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components constituting the soft segment is 2 to 100 mol%.

3. The flexible endoscope tube according to claim 1 or 2, wherein, The polyester elastomer has a naphthalene structure in the hard chain segment.

4. The flexible endoscope tube according to claim 3, wherein, The hard segment contains naphthalene dicarboxylic acid and phthalic acid.

5. The flexible endoscope tube according to claim 4, wherein, At least a portion of the phthalic acid component is isophthalic acid.

6. The flexible endoscope tube according to claim 3, wherein, The proportion of naphthalene dicarboxylic acid in all dicarboxylic acid components constituting the hard segment is 5–90 mol%.

7. The flexible endoscope tube according to claim 4, wherein, The proportion of phthalic acid in all dicarboxylic acid components constituting the hard segment is 10–95 mol%.

8. The flexible endoscope tube according to claim 5, wherein, The proportion of isophthalic acid in all dicarboxylic acid components constituting the hard segment is 10 to 40 mol%.

9. The flexible endoscope tube according to claim 1 or 2, wherein, The number-average molecular weight of the soft segments is greater than 10,000 and less than 21,000.

10. An endoscopic medical device, wherein, The endoscope has a flexible tube according to any one of claims 1 to 9.

11. A method for manufacturing a coating material constituting a flexible tube for an endoscope, wherein, The manufacturing method includes: A process for obtaining a polyester compound, wherein a polyalkylene glycol having a number average molecular weight of 1,000 or more, as a diol compound, is subjected to an esterification reaction with at least naphthalene dicarboxylic acid, as a dicarboxylic acid compound, to obtain the polyester compound; and In a process for obtaining a polyester elastomer, the polyester compound, a diol compound with a molecular weight of less than 500, and a dicarboxylic acid compound are subjected to an esterification reaction to obtain the polyester elastomer having the polyester compound as a soft segment.

12. A method for manufacturing a flexible tube for an endoscope, wherein, include: The flexible tube substrate is coated with the coating material obtained by the manufacturing method of claim 11.

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