Patent Application
20230190076
The present invention relates to a flexible tube for an endoscope, an endoscopic medical device, and methods for producing the same.
Endoscopes are medical devices for examining the inside of the body cavity, the inside of the digestive tract, the esophagus, or the like of a patient. Since endoscopes are inserted and used in the body, it is desirable to provide endoscopes that do not damage organs or cause pain or discomfort to a patient. In view of such a requirement, a flexible-tube base having a spiral tube formed by spirally winding a soft, bendable metal strip and a tubular mesh member that covers the spiral tube is employed for a flexible tube (flexible tube for an endoscope) that forms an insertion section (structural section to be inserted into the body cavity) of an endoscope. Furthermore, the periphery of the flexible-tube base is covered with a flexible resin or elastomer, and the resin or elastomer cover layer is covered with a topcoat layer as required so that the flexible tube does not cause stimulation or damage to the inner surface of, for example, the esophagus, digestive tract, or body cavity.
The flexible tube is required to have high elasticity in order to move smoothly in the body. By increasing elasticity of the flexible tube, the flexible tube that has passed through a bent portion in the body easily returns to a straight shape, and the burden on the subject during a test can be further reduced. For example, WO2019/013243A discloses, as a technology that meets this requirement, a flexible tube for an endoscope, the flexible tube having a flexible-tube base containing metal as a constituent material and a resin cover layer that covers the outer periphery of the flexible-tube base, in which a primer layer that includes an amino silane coupling agent having a specific structure is provided between the flexible-tube base and the resin cover layer, and the resin cover layer includes a polyurethane elastomer at least on the side in contact with the primer layer.
In addition, in order to smoothly and reliably deliver a tip portion of the flexible tube for an endoscope, the tip portion having a forceps port, an illumination window, etc., to an affected area or the like to obtain detailed information thereof or to perform treatment with high accuracy, it is necessary to enhance the flexibility of the flexible tube for an endoscope to improve the operability. On the other hand, since the endoscope is repeatedly used, the endoscope needs to be washed and disinfected with a chemical each time it is used. Therefore, the flexible tube for an endoscope is also required to have sufficient chemical resistance.
An object of the present invention is to provide a flexible tube for an endoscope, the flexible tube having good elasticity, good flexibility, and sufficient chemical resistance, and an endoscopic medical device that includes the flexible tube for an endoscope. Another object of the present invention is to provide a method for producing the flexible tube for an endoscope and a method for producing the endoscopic medical device.
As a result of extensive studies by the present inventors on a flexible tube for an endoscope, the flexible tube having a primer layer including a silane coupling agent, it has been found that the structure of the flexible-tube base, in particular, the structure of a tubular mesh member is important to further improve the elasticity. The present inventors have found that by using, as a tubular mesh member that forms a flexible-tube base, a mesh member made of braided metal wires and controlling the porosity of the tubular mesh member, the elasticity of the resulting flexible tube can be increased to a high level, and that the flexible tube also has good flexibility and sufficient chemical resistance. Further studies have been conducted on the basis of these findings, and the present invention has been completed.
The above objects of the present invention have been achieved by the following means.
<1>
A flexible tube for an endoscope, the flexible tube having a flexible-tube base that is tubular and that has flexibility and a polymer cover layer covering the flexible-tube base,
The flexible tube for an endoscope according to <1>, wherein the silane coupling agent includes an amino silane coupling agent.
<3>
The flexible tube for an endoscope according to <1>or <2>, wherein the polymer cover layer includes a thermoplastic elastomer.
<4>
The flexible tube for an endoscope according to any one of <1>to <3>, wherein the polymer cover layer includes, at least on a side in contact with the primer layer, at least one thermoplastic elastomer of a polyurethane elastomer, a polyester elastomer, or a polyamide elastomer.
<5>
The flexible tube for an endoscope according to any one of <1>to <4>, wherein metal that constitutes the flexible-tube base is stainless steel.
<6>
The flexible tube for an endoscope according to any one of <1>to <5>, wherein metal that constitutes the flexible-tube base has a passivation film on a surface of the metal.
<7>
An endoscopic medical device having the flexible tube for an endoscope according to any one of <1>to <6>.
<8>
A method for producing the flexible tube for an endoscope according to any one of <1>to <6>, the method including forming a primer layer including a silane coupling agent and a polymer cover layer in this order on an outer periphery of a flexible-tube base containing metal as a constituent material,
A method for producing an endoscopic medical device, the method including incorporating the flexible tube for an endoscope according to any one of <1>to <6>into an insertion section of an endoscopic medical device.
In the present specification, the term “porosity” refers to a value obtained by the calculation method described in Examples below.
The flexible tube for an endoscope according to the present invention has good elasticity, good flexibility, and sufficient chemical resistance.
A preferred embodiment of an endoscopic medical device in which a flexible tube for an endoscope according to the present invention is incorporated will be described by taking an electronic endoscope as an example. In the electronic endoscope, a flexible tube for an endoscope (hereinafter, the flexible tube for an endoscope may be simply referred to as a “flexible tube”) according to the present invention is incorporated, and the electronic endoscope is used as a medical device for, for example, observing the inside of the body by inserting the flexible tube into the body cavity, the digestive tract, the esophagus, or the like. In an example illustrated in
The flexible tube according to the present invention has a flexible-tube base that is tubular and that has flexibility and a polymer cover layer covering the flexible-tube base, and has a primer layer including a silane coupling agent between the flexible-tube base and the polymer cover layer. The flexible-tube base has a spiral tube made of a metal strip and a tubular mesh member covering the spiral tube and made of braided metal wires, and the tubular mesh member has a porosity of 2% to 10%.
The flexible tube has, as an innermost layer, a flexible-tube base containing metal as a constituent material.
In the present invention, a primer layer (not illustrated) is disposed on an outer periphery of a flexible-tube base. By providing this primer layer, it is possible to effectively enhance the adhesiveness between the flexible-tube base and a polymer cover layer which will be described later and provided to cover the outer periphery of the flexible-tube base. In the present invention, the primer layer includes a silane coupling agent.
The flexible tube according to the present invention has a polymer cover layer (a layer including at least one of a resin or an elastomer) on the outer periphery of the flexible-tube base having the primer layer thereon.
In the present invention, the polymer cover layer preferably includes a thermoplastic elastomer, and specific examples of the thermoplastic elastomer include fluorine-containing elastomers, polyolefin elastomers, acrylic elastomers, styrene elastomers, polyphenylene oxide elastomers, polyurethane elastomers, polyester elastomers, and polyamide elastomers.
In the present invention, as described later, when the polymer cover layer has a multilayer structure of two or more layers, at least the innermost layer (layer in contact with the primer layer) preferably includes at least one thermoplastic elastomer of a polyurethane elastomer, a polyester elastomer, or a polyamide elastomer, and more preferably includes a polyurethane elastomer. In the present invention, when the polymer cover layer is formed of a single layer, the single-layer polymer cover layer preferably includes at least one thermoplastic elastomer of a polyurethane elastomer, a polyester elastomer, or a polyamide elastomer, and more preferably includes a polyurethane elastomer. That is, in the present invention, the polymer cover layer preferably includes, at least on the side in contact with the primer layer, at least one thermoplastic elastomer of a polyurethane elastomer, a polyester elastomer, or a polyamide elastomer, and more preferably includes a polyurethane elastomer.
As the polyurethane elastomers used in the polymer cover layer, typical polyurethane elastomers applicable to the formation of a flexible tube can be employed. The polyurethane elastomers are each typically obtained by allowing a polyisocyanate, a polyol, and a chain extender to react with each other. The polyurethane elastomer is preferably a random copolymer or block copolymer having a soft segment formed by a reaction between a polymer polyol and a polyisocyanate and a hard segment formed by a reaction between a chain extender and a polyisocyanate, and more preferably a block copolymer.
The polyurethane elastomer is preferably a polyether polyurethane elastomer, a polyester polyurethane elastomer, or a polycarbonate polyurethane elastomer, and more preferably a polyether polyurethane elastomer.
Examples of the polyisocyanate include diphenylmethane diisocyanate, hexamethylene diisocyanate, tolidine diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate.
Examples of the polyether polyol include polytetramethylene ether glycol, polydimethylene ether glycol, polytrimethylene ether glycol, polypropylene ether glycol, polyhexamethylene ether glycol, and polyneopentyl ether glycol.
The polyester polyol is obtained by a polycondensation reaction between a dicarboxylic acid and a polyol (preferably a diol). Specific examples of the diol used in the production of polyester polyols include ethylene polyols (e.g., ethanediol), propylene polyols (1,3-propanediol), 1,3-butanediol, 1,4-butanediol, neopentyl polyols (e.g., 1,5-pentanediol), 1,6-hexanediol, and polycaprolactone diol, and these may be used alone or in combination. Examples of the dicarboxylic acid include adipic acid, sebacic acid, and dimer acid, and these may be used alone or in combination.
Examples of the polycarbonate polyol include polyethylene carbonate diol, polytetramethylene carbonate diol, and polyhexamethylene carbonate diol.
Examples of the chain extender include aliphatic linear diols having 2 to 6 carbon atoms such as ethanediol, 1,4-butanediol, and 1,6-hexanediol; and 1,4-bis(hydroxyethoxy)benzene. Amines such as hexamethylenediamine, isophoronediamine, tolylenediamine, and monoethanolamine can also be used in combination as needed.
In the present invention, typical polyester elastomers applicable to the formation of a flexible tube can be used as the polyester elastomers.
Typical polyamide elastomers applicable to the formation of a flexible tube can be used as the polyamide elastomers. In the present invention, preferably, the polyamide elastomers include neither a urethane bond nor an ester bond. The polyamide elastomers may be used alone or in combination of two or more thereof.
Specific examples of thermoplastic elastomers used in the present invention include the thermoplastic elastomers (fluorine-containing elastomers, polyolefin elastomers, polyurethane elastomers, polyester elastomers, and polyamide elastomers) used in Examples described later, but the present invention is not limited thereto.
The content of the thermoplastic elastomer in the polymer cover layer in the case of a polymer cover layer formed of a single layer and the content of the thermoplastic elastomer in the innermost layer in the case of a polymer cover layer formed of multiple layers are preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the polymer cover layer is formed of a single layer, the polymer cover layer may be a layer composed of a thermoplastic elastomer. When the polymer cover layer is formed of multiple layers, the innermost layer may be a layer composed of a thermoplastic elastomer.
When the polymer cover layer is formed of multiple layers, layers other than the innermost layer preferably include at least one thermoplastic elastomer of a polyurethane elastomer, a polyester elastomer, or a polyamide elastomer. An appropriate combination of these thermoplastic elastomers enables the formation of a layer having desired physical properties. When the polymer cover layer is formed of multiple layers, the layers other than the innermost layer more preferably include a polyester elastomer and a polyamide elastomer from the viewpoint of further enhancing elasticity.
In the present invention, a molecular weight of each of the elastomers that can be used in the polymer cover layer is preferably 10,000 to 1,000,000, more preferably 20,000 to 500,000, and particularly preferably 30,000 to 300,000.
As illustrated in
In
The soft polymer used in the inner layer 17 and the hard polymer used in the outer layer 18 preferably have a difference in 100% modulus, which is an indicator indicating a hardness after molding, of 1 MPa or more and more preferably 3 MPa or more. The difference in melt viscosity, which is an indicator indicating a fluidity of a polymer in a molten state, at a molding temperature of 150° C. to 300° C. is preferably 2,500 Pa·s or less. With this configuration, the polymer cover layer 15 composed of the inner layer 17 and the outer layer 18 reliably achieves good molding accuracy and a necessary difference in hardness between the distal end side and the proximal end side.
In the flexible tube according to the present invention, the topcoat layer 16 is disposed on an outer periphery of the polymer cover layer 15 as needed. The material of the top coat layer is not particularly limited, but a urethane coating, an acrylic coating, a fluorine coating, a silicone coating, an epoxy coating, a polyester coating, or the like is applied.
A method for producing a flexible tube for an endoscope includes forming a primer layer including a silane coupling agent and a polymer cover layer in this order on an outer periphery of a flexible-tube base containing metal as a constituent material. The method includes forming the primer layer including a silane coupling agent and the polymer cover layer in this order on at least a portion of the outer periphery of the flexible-tube base, and a primer layer including a silane coupling agent and a polymer cover layer may be formed on an inner periphery of the flexible-tube base.
In the production of the flexible tube according to the present invention, first, a primer layer is formed on the flexible-tube base. The primer layer can be formed by dissolving a silane coupling agent in a solvent to prepare a coating liquid; forming a coating film on at least an outer periphery of the flexible-tube base by, for example, applying or spraying the coating liquid onto the outer periphery of the flexible-tube base or immersing the flexible-tube base in the coating liquid; and subsequently drying the coating film by an ordinary method (for example, high-temperature drying at about 100° C.).
Prior to the formation of the primer layer, the flexible-tube base is preferably cleaned by degreasing with an alkali solution, an aqueous solution of a surfactant, an organic solvent, or the like. After the cleaning, the flexible-tube base is preferably further cleaned with water or hot water.
Formation of a polymer cover layer will be described by taking, as an example, a case where the polymer cover layer has a two-layer structure.
An example of a method for forming a polymer cover layer of the flexible tube 3a (
The inside of the die 33 is preferably heated to a predetermined molding temperature. The molding temperature is preferably set in a range of 150° C. to 300° C. The temperatures of a first polymer material 39 and a second polymer material 40 can be increased by controlling the temperatures of a heating unit in the apparatus by heating. In addition to this, as the rotational speeds of the screws 21a and 22a become higher, the temperatures of the first polymer material 39 and the second polymer material 40 can be further increased to increase their fluidity. During this process, the molding thicknesses of the inner layer 17 and the outer layer 18 can be adjusted by changing the amounts of the molten first polymer material 39 and second polymer material 40 ejected while the transport speed of the connected flexible-tube base 31 is made constant.
The process of molding the polymer cover layer 15 on the connected flexible-tube base 31 by the continuous molding machine 20 will be described. When the continuous molding machine 20 performs a molding step, the molten first polymer material 39 and second polymer material 40 are respectively extruded from the extrusion units 21 and 22 into the head unit 23. At the same time, the transport unit 25 operates so that the connected flexible-tube base 31 is transported to the head unit 23. During this process, the extrusion units 21 and 22 are in a state of constantly extruding the first polymer material 39 and the second polymer material 40 to feed the polymer materials 39 and 40 to the head unit 23, and the first polymer material 39 and the second polymer material 40 that are respectively extruded from the extrusion units 21 and 22 to gates 35 and 36 pass through an edge and join to each other, and are fed, in a stacked state, through a polymer passage 38 to a molding passage 37. As a result, a two-layer molded polymer cover layer 15 is formed in which an inner layer 17 using the first polymer material 39 and an outer layer 18 using the second polymer material 40 are stacked.
The connected flexible-tube base 31 includes a plurality of flexible-tube bases 14 (each having a primer layer on the outer periphery thereof) that are connected together. While the connected flexible-tube base 31 is transported through the molding passage 37, the polymer cover layer 15 is continuously molded on the plurality of flexible-tube bases 14. When the polymer cover layer 15 is molded from one end 14a side (distal end side) of one flexible-tube base to the other end 14b side (proximal end side) thereof, the thickness of the inner layer 17 is made large immediately after the extrusion units 21 and 22 start the ejection of the polymers. The ratio of the thickness of the outer layer 18 is then gradually increased over an intermediate portion toward the other end 14b side. It is preferable to control the amounts of the polymers ejected in this manner so as to achieve the above-described gradient thickness ratio of the polymer cover layer 15.
Joint members 30 each function as a connecting portion of two flexible-tube bases 14, and thus the control unit 26 is used to switch the amounts of the polymers ejected from the extrusion units 21 and 22. Specifically, the control unit 26 preferably switches the amounts of the polymers ejected from the extrusion units 21 and 22 such that the thickness ratio changes from a thickness ratio on the other end 14b side (proximal end side) of one flexible-tube base 14 to a thickness ratio on one end 14a side (distal end side) of the next flexible-tube base 14. When the polymer cover layer 15 is molded from the one end 14a side of the next flexible-tube base 14 to the other end 14b side thereof, the extrusion units 21 and 22 are preferably similarly controlled such that the thickness of the outer layer gradually increases from the one end side toward the other end side.
The connected flexible-tube base 31 on which the polymer cover layer 15 is molded to the rearmost end is removed from the continuous molding machine 20, and the joint members 30 are then removed from the flexible-tube bases 14 to separate the flexible-tube bases 14 from each other. Next, for each of the separated flexible-tube bases 14, the polymer cover layer 15 is coated with the topcoat layer 16 to complete flexible tubes 3a. The completed flexible tubes 3a are transported to an assembly step of an electronic endoscope.
In the present invention, when the polymer cover layer is formed of multiple layers, a functional layer may be disposed between layers that form the multiple layers.
The flexible tube according to the present invention is widely applicable to endoscopic medical devices. For example, the flexible tube according to the present invention is applicable to an endoscope equipped with a clip or wire at the distal end thereof or to a device equipped with a basket or brush. Note that the term “endoscopic medical device” is meant to broadly include medical devices or diagnosis and treatment devices that include an insertion section having flexibility and that are introduced and used in the body, such as remote-controlled medical devices, in addition to medical devices including an endoscope as a basic structure, as described above.
Hereinafter, the present invention will be described in more detail by way of Examples; however, these Examples should not be construed as limiting the present invention.
A solution having a ratio water/ethanol of 5/75 on a mass basis was prepared. A coupling agent shown in Table 1 below was dissolved in the solution so as to have a concentration of 8.9 g/kg, and the resulting solution was used as a coating liquid for forming a primer layer.
In 1 kg of methyl ethyl ketone, 100 g of a polyester polyurethane (trade name: N-2304, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 10 g of a polyisocyanate (trade name: CORONATE, manufactured by Nippon Polyurethane Industry Co., Ltd.) were dissolved, and the resulting solution was used as a coating liquid for forming an adhesive layer.
A flexible tube having the structure illustrated in
A flexible-tube base having a form in which a spiral tube 11 was formed using a metal strip 11a made of stainless steel, and the spiral tube 11 was covered with a tubular mesh member 12 made of braided stainless steel fibers (metal wires) was prepared. The spiral tube 11 used was a tube in which the width of the metal strip 11a and the gap between the strips were controlled so as to have a bending radius of 12.5 (mm). The tubular mesh member 12 having the porosity shown in Table 1 below was obtained by setting the element wire diameter (outer diameter of each of the metal wires 41) of the tubular mesh member 12 to 0.1 mm and setting the core diameter to 10.5 mm, and controlling the number of ends, the number of carriers, and the pitch in braiding (twill weaving) with a braiding machine. The outer periphery of the spiral tube 11 was covered with the tubular mesh member 12 obtained as described above to prepare a flexible-tube base.
Five 10 mm-square sheets were cut out at random from the tubular mesh member. A central region (a 5 mm×5 mm region centered on the intersection of two diagonal lines) of each of the sheets was observed with a digital microscope (VHX-200 (trade name), manufactured by Keyence Corporation) to determine the area of pores (the area of opening portions of pores) X mm2. A porosity A (%) of each sheet was determined from the following formula, and the number-average value thereof (the value (%) determined by dividing the total of the porosities A by 5) was defined as the porosity specified in the present invention.
Porosity A=100×Xmm2/25 mm2
The flexible-tube base was cleaned by immersing in a 7.5% aqueous sodium hydroxide solution at 60° C. for one minute. Subsequently, the flexible-tube base was rinsed with distilled water and then dried in an oven at 100° C. for 10 minutes. The cleaned flexible-tube base was immersed in the above-prepared coating liquid for forming a primer layer at room temperature for one minute and then dried in an oven at 160° C. for 10 minutes. Thus, a flexible-tube base having a primer layer on the outer periphery (coating surface) was prepared.
The above-prepared coating liquid for forming an adhesive layer was uniformly applied to the outer periphery of the stainless steel flexible-tube base and dried at room temperature for two hours. Subsequently, heat treatment was further performed at 150° C. for two hours to prepare a flexible-tube base having an adhesive layer on the outer periphery (resin-coated surface). The adhesive layer had a thickness of about 80 μm.
The outer periphery of the flexible-tube base having the primer layer or the adhesive layer was covered with an elastomer as shown in Table 1 below by extrusion (molding temperature: 200° C.) to prepare a flexible tube for an endoscope, the flexible tube having a polymer cover layer. The polymer cover layer had a thickness of 0.4 mm (in the case of a two-layer structure, the total thickness of the two layers was 0.4 mm).
The flexible tube for an endoscope prepared as described above was bent at a position 40 cm from one tip portion, and the radius of curvature when the flexible tube was not bent was measured and evaluated on the basis of the evaluation criteria described below. “C” or higher is satisfactory.
In an environment at a temperature of 25° C. and a relative humidity of 50%, positions 30 cm and 50 cm from one tip portion of the above-prepared flexible tube for an endoscope were fixed, and a position of 40 cm (central portion of the flexible tube) was pushed in 15 mm in a direction (diameter direction) perpendicular to the length direction of the flexible tube. A ratio of a repulsive force (b) after 30 seconds to a repulsive force (a) after 0.1 seconds was measured as an elasticity (%). The repulsive force was measured with a force gauge (ZTS5ON, manufactured by IMADA CO., LTD.).
[Elasticity (%)]=[(b)/(a)]×100
The flexible tube for an endoscope prepared as described above was sealed such that liquid did not enter the inside, and then immersed in a 7.0% aqueous peracetic acid solution at 55° C. for 150 hours. Subsequently, the surface was sufficiently washed with water. After washing with water, drying was performed at 23° C.×50% RH (relative humidity) for 24 hours. After drying, for the polymer cover layer of the flexible tube for an endoscope, a cut having a width of 1 cm and a length of 10 cm was formed in the axial direction of the flexible tube such that the cut reached the flexible-tube base. The flexible-tube base and the polymer cover layer were peeled from each other at a constant rate of 2 mm/min in the axial direction along the cut with a width of 1 cm to measure a 90° peel strength (this value is referred to as measured value X). The peel strength was measured with a force gauge (unit: N/cm). Each flexible tube for an endoscope, the flexible tube not having been immersed in the aqueous peracetic acid solution, was used to measure the 90° peel strength in the same manner (measured value Y). For all the flexible tubes, the 90° peel strength was measured under the same conditions.
Note in Tables
Fluorine-containing elastomer: DAI-EL T-530 (trade name), manufactured by Daikin Industries, Ltd.
Polyolefin elastomer: Zelas MC707 (trade name), manufactured by Mitsubishi Chemical Corporation
In Examples 1 to 39 and 44 to 46 and Comparative Examples 1 to 31, “inner” means the innermost layer of the polymer cover layer, and “outer” means the outermost layer of the polymer cover layer.
The coupling agents used in the primer layer are as follows.
The flexible tubes of Comparative Examples 1, 4, 7, 10, and 13, which had a porosity lower than the lower limit specified in the present invention, had poor flexibility. The flexible tubes of Comparative Examples 2, 3, 5, 6, 8, 9, 11, 12, 14, and 15, which had a porosity exceeding the upper limit specified in the present invention, had poor elasticity. The flexible tubes of Comparative Examples 16 to 30 each have a primer layer composed of a coupling agent other than a silane coupling agent. The flexible tubes of Comparative Examples 16 to 30 had poor elasticity, although the flexible tubes had a porosity satisfying the range specified in the present invention. The flexible tube of Comparative Example 31, which had an adhesive layer instead of the primer layer, had poor elasticity and chemical resistance.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-163598 | Sep 2020 | JP | national |
This application is a Continuation of PCT International Application No. PCT/JP2021/031740 filed on Aug. 30, 2021, which claims priority under 35 U.S.C. § 119 (a) to Japanese Patent Application No. 2020-163598 filed in Japan on Sep. 29, 2020. Each of the above applications is hereby expressly incorporated by reference, in its entirety, into the present application.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP21/31740 | Aug 2021 | US |
| Child | 18169324 | US |
