JP5455458B2 - Method for manufacturing flexible tube of endoscope - Google Patents

Description

The present invention relates to a method for manufacturing a flexible tube of an endoscope.

  A medical endoscope inserts an insertion portion into a body cavity to observe an organ or the like, or performs various treatments and treatments using a treatment tool inserted into a treatment tool insertion channel of the endoscope. For this reason, when an endoscope that has been used once is reused for other patients, it is necessary to disinfect and sterilize the endoscope after completion of examination and treatment in order to prevent infection between patients via the endoscope. There is. For disinfection and sterilization, there are methods using an autoclave that is sterilization using disinfectant solution, ethylene oxide gas, formalin gas, hydrogen peroxide gas plasma, ozone, high temperature and high pressure steam.

The hydrogen peroxide plasma method is a method in which hydrogen peroxide is decomposed by plasma to generate active hydroxy radicals, thereby sterilizing.
An autoclave that sterilizes an endoscope with high-temperature and high-pressure steam is a widely disinfected sterilization method. This method has many advantages such as high sterilization effect reliability, no residual toxicity, and low running cost. However, typical conditions for autoclaving of endoscopes are approved by the American National Standards Institute. According to the American standard ANSI / AAMI ST37-1992 issued by the Medical Device Development Association, the prevacuum type is 4 minutes at the sterilization step 132 ° C., and the gravity type is 10 minutes at the sterilization step 132 ° C.
In any of the sterilization methods, the damage to the medical device is large in the environment, and the polyurethane elastomer conventionally used for protecting the flexible tube of the insertion portion of the flexible endoscope is subjected to the hydrogen peroxide plasma treatment. Has a problem that the surface is gradually attacked by oxidation, and it is easily hydrolyzed by autoclaving to lose its function as an internal protection of the flexible tube.

  Fluororubber, which has been known to have high durability, is a material that hardly deteriorates even under heating and pressurizing conditions, and an endoscope having an outer skin made of such a fluororubber containing a black pigment. Flexible tubes have been proposed (see, for example, Patent Document 1), but there are problems with strength, in particular, abrasion resistance, and repeated storage in a cleaning instrument or a container for autoclaving, Because it wears due to friction with the holding part of the flexible tube, the inclusion of carbon black and other contents contained in fluororubber comes out as wear pieces, and the destruction progresses and the original protective function of the skin is lost Even with a skin made of fluororubber, it is impossible to obtain a highly durable flexible tube for an endoscope which is an object of the present invention.

A thermoplastic elastomer has a resinous hard phase and a soft soft phase, and the hard phase acts as a physical cross-linking point at room temperature, thereby exhibiting properties as an elastomer. Examples of such a crosslinkable thermoplastic elastomer include a triblock copolymer in which a crystalline polymer chain is bonded to both ends of an amorphous polymer chain, in which a crosslinkable bonding group is introduced into the crystalline polymer chain. It is done.
A thermoplastic elastomer has a resinous hard phase and a flexible soft layer, and the hard phase acts as a physical cross-linking point at room temperature, thereby exhibiting properties as an elastomer. However, at a high use temperature exceeding the melting point of the hard phase, the function as a crosslinking point is lost, plastic deformation occurs, and the function as an elastomer is lost.
Therefore, it is preferable to form a chemically crosslinked structure after molding of the elastomer. A triblock copolymer in which a crystalline polymer chain is bonded to both ends of an amorphous polymer chain as a thermoplastic elastomer capable of forming a crosslinked structure, in which a linking group capable of crosslinking is introduced into the crystalline polymer chain Is mentioned.
As a specific compound, a fluorine-based thermoplastic elastomer capable of radiation crosslinking is disclosed (for example, see Patent Document 2), and a transparent tube using such an elastomer is used as an outer skin for a flexible tube. Is also disclosed (see, for example, Patent Document 3).
Further, as other techniques related to durable materials, olefin-based elastomers and fluorine-based elastomers that may contain pigments have been proposed (see, for example, Patent Documents 4 and 5).
However, when each of the above elastomers is used, the destructive deterioration due to the autoclave treatment is improved to some extent, but since both are thermoplastic elastomers, there is a problem that they are thermally deformed at the autoclave treatment temperature. Specifically, these flexible tubes are usually subjected to autoclaving in a rolled state. However, there is a problem that curl is attached after the processing, and insertion into the body is deteriorated when using an endoscope. there were.

In addition, the outer skin of the flexible tube for endoscopes blocks light leaking from the illumination light guide incorporated in the built-in object for the purpose of enabling high-quality optical observation of the site to be observed, In addition to the function of blocking and protecting the internal metal core from the outside in order to prevent light scattering and light wraparound from the top, a function to block and absorb light is required. It must be colored black.
For this reason, in a conventional flexible tube skin, a black pigment has been included in the elastomer of the skin.

In the case of a thermoplastic elastomer, it is difficult to mix the pigment powder directly, and the pigment is kneaded in advance with a biaxial extruder or the like while being heated to a melting temperature with a miscible resin to obtain a colored master batch. A colored pellet containing a pigment at a high concentration is prepared, and the colored pellet is mixed with a necessary amount of the pellet of the thermoplastic elastomer for the outer shell and extruded from an extrusion molding machine to obtain a colored molded product. ing. However, in such a method using colored pellets, the resin component in the pellet is also mixed at the same time, and there is a concern that the flexibility of the thermoplastic elastomer is impaired by this resin component.
In addition, under the conditions of autoclave sterilization treatment, even if the dispersion of the pigment is not so high as to cause a problem, a fine defect is generated in the outer skin by repeated use over a long period of time. Therefore, a means for forming a light-shielding, non-light-scattering and highly durable flexible tube skin without using a colored masterbatch, and a light-shielding layer containing a pigment Therefore, there has been a demand for a flexible tube for an endoscope that has excellent durability and that does not cause a defect in the outer skin while maintaining its function as well as a manufacturing method that is excellent in productivity.

JP 2006-43347 A JP-B-2-36365 Japanese Patent Laid-Open No. 11-56762 JP 2005-21243 A JP 2005-245517 A

The present invention was made in consideration of the above problems, and even when autoclave sterilization treatment and hydrogen peroxide plasma sterilization treatment are performed, damage or deterioration of the outer skin or generation of curl is suppressed, and the necessary flexibility and Flexible tube for medical endoscopes with excellent protection and excellent durability, especially for endoscopes that have the necessary black light-shielding properties and have excellent durability with black pigment falling off An object of the present invention is to provide a highly productive manufacturing method for a flexible tube of a mirror.

As a result of intensive studies, the present inventors have found that the above problem can be solved by providing an outer skin having a multilayer structure of a light shielding layer and a layer containing a specific elastomer, and the present invention has been completed. That is, the configuration of the present invention is as follows.
As an example of the flexible tube of the endoscope obtained by the manufacturing method of the present invention , a spiral tube formed by spirally winding a band-shaped member, and a thin wire braided around the outer periphery of the spiral tube and formed into an annular shape A metal core material having a mesh tube, formed on the surface of the metal core material, containing a black pigment, a light shielding layer having a thickness of 1 μm to 100 μm, and formed on the outer periphery of the light shielding layer. comprising elastomer (hereinafter referred to as polymerization-based elastomer hereinafter) containing, include those and a large thickness transparent skin layer than the light-shielding layer.
The black pigment is preferably a black pigment selected from carbon black, titanium black, triiron tetroxide black pigment, and organic black pigment.
Here, the light shielding layer is a layer further containing a crosslinked fluororubber, and the transparent outer skin layer containing the polymerized elastomer is formed by applying energy to the composition containing the thermoplastic fluorine elastomer. A layer having a crosslinked structure is preferred.
The thermoplastic fluorine-based elastomer is preferably a block copolymer composed of a hard segment and a soft segment, and more preferably a copolymer in which a halogenated alkylene monomer is bonded to the end of the hard segment. .
Moreover, it is preferable that the thickness of a transparent outer skin layer is 200 micrometers or more and 2000 micrometers or less.

  It is preferable to further have a protective layer made of a soft fluororesin on the surface of the transparent outer skin layer containing the polymerized elastomer. That is, the flexible tube of the endoscope of the present invention has a light shielding layer on the surface of the metal core material. It is a preferred embodiment that at least three layers of a layer containing a transparent polymerized elastomer and a surface layer containing a soft fluororesin are formed.

Method for producing a flexible tube for an endoscope according to claim 1 of the present invention includes the steps of forming at least a skin layer tubular and molded into a tube by molding extruder a thermoplastic fluoroelastomer, said On the inner surface of the tube-shaped skin layer, apply a coating liquid composition in which a black pigment, a peroxide-based crosslinking agent, and a co-crosslinking agent are dispersed in a raw fluoro rubber, and then dry and heat to obtain a tube-shaped transparent outer layer. A step of obtaining a laminate in which a light shielding layer is formed on the inner surface of the skin layer, a spiral tube formed by spirally winding a band-shaped member, and an annular shape formed by braiding fine wires on the outer periphery of the spiral tube Including a step of forming an aggregate of the laminate and the metal core over a metal core having a mesh tube and a step of irradiating the aggregate with radiation in this order. And

In the production method of the present invention, after the step of forming the aggregate by covering the laminate with a metallic core material, before the step of irradiating the aggregate, the solvent is soluble in the aggregate. It is preferable to include a step of forming a protective layer by applying a paint containing a soft fluororesin. In addition to the soft fluororesin, the paint containing a solvent-soluble soft fluororesin for forming this protective layer It is preferable to include a polyfunctional co-crosslinking agent having a plurality of vinyl groups.
Furthermore, a paint containing a solvent-soluble soft fluororesin for forming a protective layer is used in a solvent selected from cyclohexanone and methylcyclohexanone, in the side chain of the main chain structure containing vinylidene fluoride and chlorotrifluoroethylene. A preferred embodiment is a paint obtained by dissolving a graft polymer having a single polymer of a ride.

According to the present invention, it has the necessary black light-shielding property, and is required by suppressing the breakage and deterioration of the outer skin or the occurrence of curl even when autoclave sterilization treatment and hydrogen peroxide plasma sterilization treatment are performed. flexibility and protection is maintained, the flexible tube for medical endoscopes having excellent durability, in particular, and, of an endoscope dropping of black pigment superior in the suppression durability of the flexible tube A production method with high productivity can be provided.

It is a schematic block diagram which shows the endoscope obtained by the manufacturing method of this invention . It is sectional drawing which shows the structure of the flexible tube of the endoscope which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the flexible tube of the endoscope which concerns on 2nd Embodiment.

Hereinafter, an example of an embodiment of an endoscope manufactured by the manufacturing method of the present invention (hereinafter sometimes referred to as an endoscope according to the present embodiment) will be described with reference to the drawings.
First, the overall configuration of the endoscope 10 according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an endoscope 10 according to the present embodiment.

  As shown in FIG. 1, the endoscope 10 according to the present embodiment includes a long insertion portion 12 to be inserted into a body cavity of a patient. The part 14 is continuously provided. A long light guide flexible portion 16 that is detachably connected to a light source device (not shown) is connected to the main body operation portion 14. A connecting portion 18 having a terminal connected to a light source device (not shown) is provided at the distal end portion of the light guide flexible portion 16. The main body operation unit 14 is provided with an operation knob 20 for operating the insertion unit 12.

  The insertion portion 12 is connected to the flexible tube 12A constituting most of the length in the longitudinal direction (axial direction) from the continuous portion to the main body operation portion 14, and to the distal end side in the longitudinal direction of the flexible tube 12A. Angle portion 12B, and a distal end portion main body 12C that is connected to the distal end side in the longitudinal direction of the angle portion 12B and incorporates an objective optical system and the like.

  The angle portion 12B is configured to be bent remotely by rotating the operation knob 20 provided in the insertion portion 12. Further, the light guide soft portion 16 has a structure substantially similar to that of the flexible tube 12A of the insertion portion 12.

  The flexible tube 12A has a length that allows the distal end main body 12C to reach a predetermined observation target portion, and does not hinder the operator from gripping and operating the main body operation portion 14. It is set to a length that can be separated from the patient. The flexible tube 12A needs to have flexibility over almost the entire length thereof, and in particular, a portion to be inserted into a body cavity of a patient has a more flexible structure.

  In addition, the flexible tube 12A needs to have a predetermined rigidity with respect to bending in order to obtain a pushing propulsion force when inserted into a body cavity or the like, particularly at a portion connected to the main body operation unit 14. Further, it is preferable that the flexible tube 12A is more flexible particularly in a portion connected to the angle portion 12B in order to follow the curved shape to some extent when the angle portion 12B is curved.

  The flexible tube 12A includes a light guide, an image guide (a signal cable in the case of an electronic endoscope), a treatment instrument insertion channel, an air / water supply tube, and the like (not shown) in the tubular portion.

FIG. 2 is a cross-sectional view of the flexible tube 12A according to the first embodiment obtained by the manufacturing method of the present invention. FIG. 3 shows a cross-sectional view of a flexible tube 42A according to the second embodiment having a protective layer 40 on the outermost surface of the flexible tube 12A according to the first embodiment.
As shown in FIG. 2, the flexible tube 12A according to the first embodiment of the present invention includes a spiral tube 32 formed by spirally winding a band-shaped member, and a thin wire braided on the outer periphery of the spiral tube. A light-shielding layer 36 is formed on the surface of a metal core material having a net-shaped tube 34 formed in an annular shape, and is formed on the outer periphery of the light-shielding layer 36. A transparent skin layer 38 containing FIG. 3 has the same configuration as that of the first mode shown in FIG. 2 except that a protective layer 40 is provided on the surface of the transparent skin layer 38.

Hereafter, each layer which comprises the flexible tube concerning this embodiment, and the material which comprises this layer are demonstrated in detail with the manufacturing method.
(Transparent skin layer)
First, the transparent outer skin layer that is an important component of the present embodiment will be described. Here, the term “transparent” means that the formed outer skin layer does not have maximum absorption in the visible light region.
The transparent skin layer in the flexible tube for an endoscope according to the present invention contains an elastomer (polymerized elastomer) made of a polymerized polymer. Here, the polymerized elastomer means that the elastomer is composed of a polymer obtained by addition polymerization of a compound having a vinyl group, and is an elastomer obtained by a condensation reaction, specifically, a urethane-based elastomer or a polyester-based elastomer. Elastomers and the like are not included in the polymerized elastomer referred to in the present invention.
As the polymerization elastomer used in the present invention, any polymerization elastomer can be used as long as it does not melt at the heating temperature in the autoclave treatment or does not cause remarkable creep even if it does not melt.
Examples of the polymerized elastomer having autoclave resistance as described above include, as a hard segment of a styrene elastomer, an elastomer made of diphenylethylene instead of styrene, or an elastomer made of adamantyl styryl group.
Particularly preferable polymerized elastomers include polymerized elastomers that can form a crosslinked structure by applying energy such as irradiation with radiation or heating.

The polymerized elastomer that can be used in the present invention is preferably a thermoplastic fluorine-based elastomer, and more preferably a thermoplastic fluorine-based elastomer that can form a crosslinked structure by applying energy such as radiation irradiation.
The thermoplastic fluorine-based elastomer is preferably a block copolymer composed of a hard segment and a soft segment.
Examples of the hard segment include polymers selected from vinylidene fluoride, vinylidene fluoride / tetrafluoroethylene, and ethylene / tetrafluoroethylene.
Soft segments include vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene, vinylidene fluoride / tetrafluoroethylene / perfluoroalkyl vinyl ether, and tetrafluoroethylene / perfluoroalkyl vinyl ether. It is done.
The thermoplastic fluorine-based elastomer is preferably a copolymer containing both of these hard segments and soft segments, and the content ratio of the hard segments to the soft segments is 5 to 60 parts by weight for the hard segments and 40 for the soft segments. To 95 parts by weight.
Among these, a hard segment made of ethylene / tetrafluoroethylene is more preferable because of its high durability to solvents.
The weight average molecular weight of such a thermoplastic fluorine-based elastomer is preferably in the range of 50,000 to 1,500,00. The weight average molecular weight of the thermoplastic fluorine-based elastomer can be measured by, for example, a size exclusion chromatography method.

The transparent skin layer according to the present invention preferably has a crosslinked structure in the finally formed layer, and the crosslinked structure is formed by forming a transparent skin layer of a flexible tube and then applying energy, preferably by irradiation with radiation. It is formed. By forming a cross-linked structure, the heat resistance of the outer skin layer is improved. For example, even when the flexible tube is wound in the autoclave process, it has an advantage that it is difficult to be curled due to thermal deformation. become.
From the viewpoint of the formability of the crosslinked structure, it is most preferable that a halogenated alkylene monomer, particularly an alkylene iodide monomer, is bonded to the end of the hard segment so that crosslinking in the hard segment contained in the polymerized elastomer is facilitated. .
Commercially available products can be used as the polymerized elastomer constituting the transparent outer skin layer according to the present invention. Specific examples of the compound include Daiel Thermoplastic, T-530 (vinylidene) manufactured by Daikin Industries, Ltd. Fluoride / hexafluoropropylene / ethylene / tetrafluoroethylene copolymer) and T-630 (vinylidene fluoride / hexafluoropropylene / vinylidene fluoride copolymer).

  In the present invention, the thickness of the transparent outer skin layer is not particularly limited as long as the thickness is larger than the light shielding layer described later, and is appropriately selected depending on the flexible diameter and use of the endoscope. From the viewpoint of protection and durability, it is preferably at least about 200 μm or more, and from the viewpoint of not impairing flexibility, it is preferably 2000 μm or less.

The transparent outer skin layer according to the present invention is preferably a layer composed of the above-mentioned polymerized elastomer alone, and in particular, an embodiment that does not include a colorant (pigment) and a dispersing resin or dispersing aid for dispersing the pigment. preferable.
The transparent skin layer is preferably formed by heating a polymerized elastomer and molding it by a melt extrusion method.

(Light shielding layer)
The flexible tube 12 </ b> A of the endoscope according to the present embodiment includes a light shielding layer 36. The light shielding layer 36 is formed by dispersing a black pigment in fluororubber. The fluororubber is preferably a fluororubber obtained by crosslinking a liquid rubber.
As the fluoro rubber, binary or ternary normal fluoro rubber can be arbitrarily used. Specifically, for example, vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene, vinylidene fluoride / tetrafluoroethylene / perfluoroalkyl vinyl ether, tetrafluoroethylene / perfluoroalkyl vinyl ether, tetra Examples include fluoroethylene / propylene and tetrafluoroethylene / propylene / vinylidene fluoride.

Any rubber vulcanization (crosslinking) method may be used, and any vulcanizing agent and vulcanization aid may be used in combination.
For example, a peroxide vulcanization method using an organic peroxide, a polyphenol vulcanization method using calcium oxide and a polyphenol compound, an amine vulcanization method using an amine compound, and the like. It is more preferable in that there are few residues and by-products. The crosslinking agent can be arbitrarily selected from organic peroxides according to the crosslinking conditions, and is typically 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dioxane. Examples thereof include milperoxide.
When the organic peroxide is used, the addition amount is preferably in the range of 1% by mass to 10% by mass with respect to the rubber component constituting the light shielding layer.
In the organic peroxide vulcanization method, it is preferable to add a polyfunctional vinyl compound as a co-crosslinking agent for the purpose of increasing the crosslinking efficiency. Examples of such a co-crosslinking agent include triallyl isocyanurate and trimethacrylic acid. An isocyanurate etc. are mentioned.
When the co-crosslinking agent is used, the addition amount is preferably in the range of 2% by mass to 10% by mass with respect to the rubber component constituting the light shielding layer.

The black pigment contained in the light shielding layer may be arbitrarily selected as long as it can achieve a desired light shielding property. For example, carbon black, titanium black, triiron tetroxide-based black pigment, Black pigments can be used. The black pigment may be a multicomponent pigment composition having a function of whitening by laser irradiation.
As content of the black pigment contained in a light shielding layer, it is preferable from a light-shielding viewpoint that it is the range of 5 mass% to 50 mass% with respect to the whole composition which comprises a light shielding layer, More preferably, it is 10 The range is from 30% by mass to 30% by mass.
A composition for forming a light shielding layer for forming a light shielding layer is prepared by thoroughly mixing fluororubber, a black pigment, and a crosslinking agent added if desired. Specifically, when the light shielding layer is formed by extrusion molding, each component of the light shielding layer forming composition is prepared by kneading in the same manner as a rubber kneading method generally used.
Moreover, when forming a light shielding layer by apply | coating a solution, the coating liquid composition for light shielding layer formation is prepared by dissolving a rubber component, a pigment, a crosslinking agent, etc. in a solvent, stirring.
Examples of the solvent used for the preparation of the coating solution composition include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and isobutyl acetate.
The light shielding layer forming composition thus formed is brought into close contact with a transparent outer layer formed in advance by an extrusion method, a coating method, or the like, and then heat-cured to form a light shielding layer. After laminating the transparent outer skin layer and the light shielding layer, it is preferable to form a crosslinked structure of fluororubber contained in the light shielding layer by heating.

Crosslinking of the fluororubber constituting the light shielding layer can be performed by heating. The crosslinked structure may be formed after the light-shielding layer and the transparent outer skin layer are laminated, and may be in the middle of forming the flexible tube or in the final stage after all processing is completed. It may be carried out several times. By laminating an uncured light-shielding layer on the outer skin layer and heating it to cure the light-shielding layer, the fluoroelastomer is cured and the fluoroelastomer layer constituting the outer skin layer laminated is cross-linked with the fluororubber layer. This also has the advantage of being integrated more firmly.
The thickness of the light shielding layer is required to be 1 μm to 100 μm, and preferably 10 μm to 50 μm. If this thickness is too thin, sufficient light shielding properties cannot be ensured, and if the proportion of the thickness of the light shielding layer is high, the effect of the transparent outer skin layer is reduced.

(Formation of transparent skin layer and light shielding layer)
Method of manufacturing a flexible tube of the present invention, the durability of the viewpoint et productivity and the formed flexible tube, at least, extruding a thermoplastic fluoroelastomer molding machine tubular and molded into a tube by Applying a coating liquid composition for forming a light-shielding layer formed by dispersing a black pigment, a peroxide-based crosslinking agent, and a co-crosslinking agent in a raw fluoro rubber on the inner surface of the tubular skin layer to, and dry heat, forming a laminate shielding layer is formed into a tube-shaped transparent skin layer inner surface, by performing, in this order, Ru is adhered to both layers.

First, a thermoplastic fluoroelastomer is molded into a tube shape by an extrusion molding machine to form a cylindrical outer skin layer (elastomer tube) that constitutes a transparent outer skin layer, and on the inner surface of the outer skin layer formed into the tubular shape, A laminate in which a composition obtained by dispersing a black pigment, a peroxide-based crosslinking agent and a co-crosslinking agent on a raw fluororubber is applied or extruded and then dried and heated to form a light-shielding layer on the inner surface of the outer skin layer Form the body .
Na us, that improves the adhesion of both layers in the heat drying process, a good dispersion of the pigment, is by thin black considering the point that they can uniformly form a light shielding layer of optimum formation by coating method It can be said that there is.

(Formation of integrated body of metal core and laminate)
The laminated body of the transparent outer skin layer and the light shielding layer obtained as described above is covered with a metallic core material to form an integrated body, so that the light shielding layer and the transparent elastomer outer layer are formed on the surface of the flexible tube. A skin layer is formed. At this time, it is preferable to adhere and fix the light shielding layer and the metal core material by covering the surface of the metal core material with a primer and then covering the laminate.
Examples of the primer include silane coupling agents, titanate coupling agents, zirconate coupling agents, and the like, and it is preferable to use silane coupling agents.
As the silane coupling agent, methoxysilane and ethoxysilane having a vinyl group are preferable. Specific examples include vinyltrimethoxysilane and vinyl-containing ethoxysilane.
As a bonding method, a dilute solution of a silane coupling agent is applied to the surface of a metal core material, dried, and heat-treated as necessary, and then brought into close contact with the light-shielding layer. The metal core material is vulcanized and bonded to obtain an aggregate of the transparent outer skin layer, the light shielding layer, and the metal core material.
As described above, it is a feature of the manufacturing method of the present invention that the light-shielding layer formed in advance is adhered to the surface of the metal core to form an integrated body. As a result, the inner surface of the light-shielding layer (the surface in contact with the core material) is firmly bonded only at the portion in contact with the mesh tube, which is the outermost layer of the metal core material, and the flexibility of the mesh tube is good. Combined with the high stretchability of the light-shielding layer mainly composed of fluororubber and the transparent outer skin layer mainly composed of elastomer adhering to the light-shielding layer, it has excellent flexibility and durability. Get a flexible tube.
When the light shielding layer is provided on the metal core by a coating method, the fluororubber constituting the light shielding layer penetrates into the gaps between the fine metal wires of the mesh tube and is cured. Accordingly, the extremely thin rubber layer existing between the fine metal wires is easily broken and peeled off, which is not preferable from the viewpoint of durability.

(Irradiation of the laminated body and metal core material)
The flexible tube for an endoscope according to the present embodiment is obtained by irradiating the integrated body of the transparent outer skin layer, the light shielding layer, and the metal core material with radiation.
Irradiation treatment for the outer skin layer made of a thermoplastic fluorine-based elastomer that is a polymerized elastomer is indispensable. By this irradiation, a crosslinked structure is formed in the outer skin layer, and physical strength and heat resistance can be improved.
Irradiation may be performed on the light-shielding layer and the material contained in the protective layer, which is an optional layer described later, as necessary. In particular, when the protective layer described later contains a crosslinking component or the like, it is preferable because the strength and durability of the protective layer located on the outermost surface of the flexible tube are further improved by irradiation with radiation. In this case, a protective layer may be formed on the surface of the assembly with the metal core material, and after all the steps have been completed, the entire flexible tube may be finally subjected to radiation treatment.

As the radiation, γ rays or electron beams may be used as long as the radiation has energy capable of uniformly irradiating the transparent outer skin layer containing the thermoplastic fluorine-based elastomer. Among these, γ rays using 60Co as a radiation source are more preferable because they can be processed in a form integrated with a metal core material.
The radiation dose is preferably in the range of 5 kGy to 500 kGy, more preferably 30 kGy to 200 kGy. When the irradiation amount is small, the radiation crosslinking does not proceed, and when it is too large, there is a concern that the material is deteriorated.
From the viewpoint of efficiently forming a cross-linked structure, it is preferable that the irradiation of radiation is performed in an environment that is not affected by oxygen. For example, the irradiation is performed under a nitrogen blow, or the flexible tube has an oxygen barrier property. It is preferable to carry out in the state enclosed with the oxygen scavenger in the packaging bag.
Heat treatment may be performed as necessary after irradiation. By performing the heat treatment, distortion caused by processing can be removed, and volatile residues or by-products can be removed.

(Protective layer)
In order to improve durability, the flexible tube manufactured by the manufacturing method of the present invention may further be provided with a protective layer on the surface of the transparent outer skin layer.
The resin for forming the protective layer is preferably a polymerized elastomer used for the transparent outer skin layer, for example, a soft fluororesin having a hardness higher than that of the thermoplastic fluorine-based elastomer. From the viewpoint of easy formation of the protective layer, the solvent is soluble. The fluororesin is preferable.
Although the boundary between the thermoplastic fluoroelastomer and the soft fluororesin is not clear, in the present invention, a material having a hardness of about A70 or less in Shore hardness is referred to as a fluoroelastomer and measured by Shore D hardness exceeding A80. Those having a possible hardness range are called flexible fluororesins.
Such a fluorine-based soft resin can be selected from a copolymer of a monomer component that gives a crystalline polymer and an amorphous polymer component.

Specifically, for example, a copolymer of trolafluoroethylene / hexafluoropropylene / vinylidene fluoride can be mentioned. This is the same composition as fluororubber, but by controlling the copolymerization ratio, unlike a copolymer in the rubber-like region, it can be made a resin of moderate flexibility, and such a resin is suitable. Can be used. The composition region capable of forming the soft resin is described in US Pat. No. 3,235,537, and the soft resin described here can also be used in the present invention.
Another example of the soft resin is a resin obtained by graft-polymerizing a crystalline polymer to an amorphous polymer. For example, a graft polymer obtained by grafting a vinylidene fluoride monopolymer as a branch polymer onto a vinylidene fluoride hexafluoropropylene or vinylidene fluoride / chlorotrifluoroethylene trunk polymer may be mentioned.
The soft fluororesin used for the protective layer is also available as a commercial product. For example, as the solvent-soluble soft resin of the former type, THV220A manufactured by Sumitomo 3M Co., Ltd. is used as the latter soft resin. Examples include Cefral Soft G120, G150, G180 manufactured by Glass Co., Ltd. Among them, cefral soft is preferable from the viewpoint of strength and heat resistance.

In the production method of the present invention, the protective layer is provided by dissolving the flexible resin as described above in a solvent and applying and drying. The solvent for dissolving the soft resin is not particularly limited as long as it can dissolve the resin to be used at a desired resin concentration.
In the present invention, a polymer in which a vinylidene fluoride single polymer is grafted on the main chain portion of vinylidene fluoride / chlorotrifluoroethylene that is most preferably used (for example, Cefral Soft manufactured by Central Glass Co., Ltd.) is usually used. For example, as is conventionally used, the coating solution is first prepared by dissolving the resin in dimethylformamide and then diluting with methyl ethyl ketone, and then applying and drying the solution. Then, there exists a problem that a film | membrane tends to become cloudy. For this reason, when using such resin, it is preferable to use cyclohexanone as a solvent. By adjusting the solution in a heated state using cyclohexanone, it is possible to dissolve at a high concentration and to obtain a specific property of gelation without precipitation due to cooling.
Therefore, when using such a specific graft copolymer, by using the property of gelation using cyclohexanone as a solvent, there is no occurrence of turbidity during film formation by solution coating, Further, there is an advantage that a protective layer having a uniform film thickness can be formed without the problem of dripping during drying.

  More preferably, the protective layer-forming coating solution contains a co-crosslinking agent containing a plurality of unsaturated bonds in addition to the soft fluororesin. By including a co-crosslinking agent and then performing the radiation irradiation described above, the heat resistance of the protective layer is improved, the adhesion strength between the protective layer and the transparent outer skin layer is improved, and more physical durability and thermal durability. A flexible tube having excellent properties can be obtained. The co-crosslinking agent used here may be the same as that described for the outer skin layer, and the amount contained in the protective layer forming coating solution is the same as that for the transparent outer skin layer.

Examples of the protective layer coating method include dip coating, spray coating, and slit coating method in which liquid is discharged from the slit of the coating head onto the transparent outer skin layer. Among these, the dip coating method is a predetermined thin protective layer. From the viewpoint that a coating film can be formed.
The thickness of the protective layer needs to be a thickness sufficient to protect the outer skin from damage due to wear. On the other hand, if the thickness is too thick, the flexibility of the outer skin is impaired. More preferably, the thickness is in a range of 30 μm or less and 2 μm or more.

Hereinafter, by way of actual 施例 will be specifically described the invention, the present invention is not limited to the embodiments, various modifications, changes, improvements are possible.
In the following examples, “part” represents “part by mass” and “%” represents “% by mass”.
[Examples 1 to 3, Reference Example 4]
A metal core material having an outer diameter of 5.0 mm and a length of 550 mm made of a spiral tube and a mesh tube made of SUS304 was manufactured.
A pellet of Thermoplastic T-530 manufactured by Daikin Industries was used as a raw material and extruded at a head temperature of 230 ° C. using a resin extrusion molding machine to produce a transparent tubular skin layer having an outer diameter of 6 mm and an inner diameter of 5 mm.
Next, this tube is cut every 550 mm, the cut tube is connected to a liquid feeding device, and a coating solution composition for forming a light shielding layer containing fluororubber having the following composition is distributed inside the tube. After drying, the coating solution composition was cured by heat treatment at 160 ° C. for 5 minutes in a nitrogen atmosphere. As a result, a 30 μm thick semi-vulcanized fluororubber-containing light shielding layer having a thickness of 30 μm was formed to obtain a laminate of the transparent outer skin layer and the light shielding layer.

(Coating solution composition for forming a light shielding layer)
・ Daiel G-902 (Fluorine raw rubber made by Daikin Industries) 30 parts ・ MT carbon black 6 parts ・ Perhexa 25B (manufactured by NOF Corporation: Peroxide vulcanizing agent) 0.5 parts ・ Taiken (Nippon Kasei Co., Ltd.) ): Co-crosslinking agent) 1.2 parts ・ Methyl ethyl ketone (MEK, solvent) 70 parts

The metal core was treated with a 0.1% trimethoxyvinylsilane hydrous alcohol solution as a primer, and then heated at 150 ° C. Subsequently, the tube produced above was covered, and the core material and the laminated body obtained above were vulcanized and bonded by heating for 10 minutes under a 160 ° C. hot nitrogen flow to form an integrated body.
Next, this aggregate was irradiated with γ rays (50 kGy) under deoxidation to form a crosslinked structure in the transparent outer skin layer, and a flexible tube (A) of Example 1 according to the present invention was produced.

Also, before performing the irradiation in an integrated body of the resulting metal core material and the product layer body in the manner described above, on the surface, soft fluororesin (Central Glass Sefurarusofuto G-150) 5%, tri A solution obtained by dissolving 0.25% allyl isocyanurate in a cyclohexanone solution at 100 ° C. was dip-coated, and a protective layer was placed.
Finally, the aggregate with the protective layer formed on the surface is irradiated with radiation in the same manner as in the sample (A) to crosslink the outer skin layer, and to form a crosslinked structure between the outer skin layer and the protective layer, A flexible tube (C) of Example 3 was produced in the same manner except that the flexible tube (B) of Example 2 according to the present invention and the thickness of the light shielding layer were different.
Further, a flexible tube manufactured in the same manner as the flexible tube (A) of Example 1 and not exposed to radiation was manufactured, and the flexible tube (D) of Reference Example 4 was obtained.

[Comparative Examples 1-4]
Instead of the light-shielding layer and the outer skin layer, 10 parts of a black fluoropolymer-based black color masterbatch (HTV-500 black masterbatch manufactured by Colorant Chromatics) per 100 parts of pellets of Daikin Industries Thermoplastic T-530 The flexible tube (E) of Comparative Example 1 was prepared by coating the mixture obtained by coating on the same metal core material as that of the present invention and performing radiation crosslinking in the same manner.
Also, after impregnating the same black rubber paint as that used in the flexible tube (A) with the same metal core material as in the present invention to form a black monolith, a tube-like transparent film without a light shielding layer thereon The flexible core (F) of Comparative Example 2 was covered with only the outer skin layer and vulcanized and bonded to the metallic core material impregnated with the black rubber paint and the transparent outer skin layer by heating at 180 ° C. for 1 hour in a nitrogen atmosphere. It was.
Moreover, the flexible pipe (G) of the comparative example 3 which added the black masterbatch which disperse | distributed carbon to polypropylene resin to Mitsubishi Chemical Corp. ZERAS MC707 which is an olefin elastomer, and formed the black skin layer by extrusion molding. A black outer layer was formed by extrusion molding by adding a black masterbatch in which curbone black was dispersed in polyurethane resin to milactolan E399 manufactured by Nippon Milactolan Co., Ltd., which is a polyurethane elastomer (elastomer made of condensation polymer). The flexible tube (H) of Example 4 was produced.

The following evaluation was performed about each produced flexible tube.
(1) Durability test for autoclave treatment In a state where a flexible tube is wound so that the radius of curvature is 20 cm, it is set in an autoclave device and left at 135 ° C. for 4 weeks to perform a durability test. I did it.
After taking out, observe the appearance of the outer skin with a change in appearance, observe the degree of bending folds while hanging vertically, and determine the degree of bending folds from the extent to which the lower end of the flexible tube moves away from the vertical line. did.
In addition, the change in elasticity of the flexible tube before and after the autoclave treatment was examined.
Judgment criteria ◎: Change in elasticity is not recognized ○: Change in elasticity is within 20%,
Δ: Change in elasticity is greater than 20% and within 40% ×: Change in elasticity exceeds 40% (2) Bending durability test Each test specimen 10 cm in length was prepared using a test machine. Criteria for examining change in resilience after initial and after test after 2000 repeated flex tests using: ◎: No change in resilience ○: Change in resilience is within 20%,
Δ: Change in elasticity is greater than 20% and within 40% ×: Change in elasticity exceeds 40% (3) Abrasion test Each sample of 10 cm in length, created separately, is repeatedly rubbed with a standard test piece The outer skin was observed from the surface observation after the test.
The obtained results are shown in Table 1.
Judgment criteria ◎: Wear is not recognized ○: Wear depth is less than 5μ
Δ: Wear depth of 5 μm or more and less than 50 μm ×: Wear depth of 50 μm or more

From the results shown in Table 1, none of the flexible tubes manufactured by the manufacturing method of the present invention was changed in appearance and elasticity even in autoclave treatment, and was excellent in both bending durability and wear resistance. . Also. In Example 2 and Example 3 in which the protective layer was formed, the wear resistance was further improved.
In addition, it can be seen from the comparison between Example 1 and Reference Example 4 that the effect of suppressing bending wrinkles by the autoclave treatment is further improved by irradiating with radiation to form a high-density crosslinked structure.
On the other hand, in Comparative Example 4 using a conventionally used polyurethane elastomer, the outer skin layer was easily decomposed by autoclaving, and in Comparative Example 3 having an outer skin layer made of an olefin elastomer, the outer skin layer was decomposed. What did not do caused thermal deformation, and extreme curl was attached. From this, it can be seen that, in contrast to the flexible tube using the condensation type elastomer, the performance of the flexible tube of the example using the polymerization type elastomer is not deteriorated even in the autoclave treatment.
In addition, the flexible tube of Comparative Example 1 using a fluoroelastomer and containing a colored outer skin layer containing a black material in the same manner as the conventional flexible tube has an unacceptable curl. Furthermore, the flexible tube of Comparative Example 2 in which the fluororubber was integrated by immersing the net tube in the net tube had a practically problematic level because the elasticity was greatly reduced by repeated bending, although it did not cause curling. .

10 Endoscope 12A Flexible tube 32 Spiral tube 34 Reticulated tube 36 Light shielding layer 38 Transparent skin layer 40 Protective layer

Claims (4)

At least a step of forming a tubular skin layer by molding a thermoplastic fluorine-based elastomer into a tubular shape by an extrusion molding machine,
A coating liquid composition in which at least a black pigment and a cross-linking agent are dispersed in fluoro raw rubber is applied to the inner surface of the tubular skin layer, and dried and heated to form a light shielding layer on the inner surface of the tubular skin layer. Obtaining a laminated body,
The laminate is covered with a metal core having a spiral tube formed by spirally winding a band-shaped member, and a mesh tube formed by braiding fine wires on the outer periphery of the spiral tube, and the laminate Forming an assembly of the body and the metal core;
Irradiating the aggregate with radiation;
For producing a flexible tube for an endoscope A coating liquid composition comprising a solvent-soluble soft fluororesin in the aggregate between the step of forming an aggregate of the laminate and the metal core and the step of irradiating the aggregate with radiation. the by coating and drying comprising the step of forming the protective layer, the manufacturing method of the flexible tube according to claim 1 The method for producing a flexible tube for an endoscope according to claim 2 , wherein the coating liquid composition containing the solvent-soluble soft fluororesin further contains a polyfunctional co-crosslinking agent. The coating liquid composition containing the solvent-soluble soft fluororesin is a single polymer of vinylidene fluoride in the side chain of the main chain structure containing vinylidene fluoride and chlorotrifluoroethylene in a solvent selected from cyclohexanone and methylcyclohexanone method for producing a flexible tube for an endoscope according to claim 2 or claim 3 is a coating liquid composition obtained by dissolving a graft polymer having a.

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