JP2007195959A - Medical tube and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin medical tube having a small outer diameter, an excellent mechanical characteristic, and an inner wall of the tube of a low frictional resistance value, having the inner fluroresin layer and the outer layer formed of the mixture of a polyimide resin and fluororesin, which are fused strongly, safety to human bodies, and high reliability, and its manufacturing method. <P>SOLUTION: The inner layer is formed from fluororesin on the surface of a metal core wire, and then the mixture liquid of a polyimide precursor solution and a fluororesin is coated on the outer surface of the inner layer, and it is heated at the temperature over the melting point of the fluororesin mixture, and the fluororesin mixture is melted and deposited on the inner side of the outer layer to be integrally fused with the fluororesin inner layer to obtain the medical tube. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a medical tube whose inner layer is made of a fluororesin and whose outer layer is a mixture of a polyimide resin and a fluororesin. Specifically, because the inner layer is made of pure fluororesin, the friction resistance is extremely low, the outer layer has the excellent mechanical properties of polyimide resin, and the inner layer and outer layer are firmly fused and integrated into a catheter, etc. It is related with the medical tube suitable for.

  Polyimide resins have excellent properties such as mechanical, chemical, electrical and heat resistance, and are commercially available in the form of molded articles such as films and tubes, or polyimide precursor solutions and paints. These polyimide resins are used in various applications such as flexible printed circuit boards, tubular materials used in processes such as transfer, fixing, and photosensitivity in OA equipment, and insulating materials for heat-resistant electric wires. (0.1 to 5 mm) tubes are expected as uses for medical tubes such as catheters and endoscopes, or electrical insulating tubes.

  Here, a medical tube that is one application of the polyimide resin tube will be described. In recent years, with the advancement of medical technology, instead of the conventional incision surgery method, the treatment method is a catheter treatment method in which a medical instrument such as a catheter is inserted directly into the patient's body vagina, or a gastric camera. Alternatively, endoscopic diagnostic methods for treatment using an image diagnostic apparatus such as a micro camera have become mainstream. These treatment methods are intended to reduce the physical or mental pain and anxiety of the patient at the time of treatment, and to perform treatment while minimizing the exhaustion of physical strength due to the treatment. Medical tubes are used in applications such as catheters and endoscope tubes or blood and pharmaceutical delivery tubes in such new medical technologies and medical settings.

  In the catheter treatment method, treatment is performed by inserting a catheter into a blood vessel or a tube that is arranged in a complex manner in the body by guiding a guide wire. For this reason, the catheter is easy to push into the blood vessel (pushability), or the rotational force or dynamic operation operated at the proximal end (hand side) of the catheter is reliably transmitted to the distal end of the catheter ( In addition, in order to prevent an accident that damages the blood vessel at the tip of the catheter, characteristics such as kink resistance and flexibility of the tip are required. In order to reduce the pain and anxiety of the patient, it is desired that the inner vagina be as large as possible with a small diameter and a thin wall (thin thickness).

  Further, these catheters are required to have low friction on the inner and outer surfaces of the catheter in addition to the mechanical characteristics such as torque transmission and pushability. That is, in the catheter treatment method, the treatment catheter is inserted into a guiding catheter that guides the treatment catheter to the diseased part, and is guided to the diseased part by the guide wire. In such an operation, since the outer surface of the treatment catheter contacts the inner wall of the guiding catheter and the inner surface contacts the outer surface of the guide wire, the low friction of the inner and outer surfaces of the treatment catheter is also reduced. One of the important characteristics.

  In a medical tube used for these catheters, as a method of reducing the frictional resistance of the inner surface, for example, after coating a fluororesin dispersion on the outer surface of a silver-plated annealed copper wire and solidifying to form a fluororesin film, Patent Document 1 discloses a method in which a fluororesin coating surface is chemically etched, a polyimide varnish is coated on the chemically etched fluororesin coating surface and solidified, and then the silver-plated annealed copper wire is stretched and contracted to obtain a medical tube. It is disclosed.

  Also, PTFE resin dispersion is applied, baked, and sintered on a mandrel rod, then solid particle-containing PTFE resin dispersion is applied, baked, and sintered to form a solid particle-containing PTFE resin overcoat pure PTFE tube. A method for producing a tube in which an outer covering layer is extruded or coated directly after a blade layer is formed on a tube, a mandrel rod is finally pulled out, and an inner layer PTFE composite catheter tube is taken out, and an inner layer PTFE composite catheter tube is disclosed in Patent Document 2. Yes.

  However, the conventional method has the following problems. That is, in the method described in Patent Document 1, a solution such as a sodium-naphthalene complex is used in the manufacturing process of a medical tube, and the fluororesin coating surface is etched by a chemical method to adhere to the polyimide outer layer. There is a need. The excellent releasability and non-stickiness of fluororesins are used in many applications such as frying pans and rice cookers, but it is naturally difficult to bond to other objects and is disclosed in Patent Document 1. As described above, a process of chemically etching the surface of the fluororesin using metal sodium or the like and then adhering it to another object is required. These surface treatments not only make the manufacturing process complicated, but chemical etching with sodium-naphthalene complex has a high risk of chemicals used, and it is also safe for use in the human body. There are many problems.

  In addition, the method disclosed in Patent Document 2 has a heat softening point equal to or higher than the sintering temperature of the PTFE resin in order to improve the adhesive strength between the thin-walled PTFE inner layer tube and the polyamide elastomer layer to be extruded as the outer layer. PTFE intermediate layer of solid particles blended with inorganic substance powder such as silicon dioxide, calcium carbonate, magnesium carbonate, magnesium oxide, alumina, titanium dioxide, glass powder, potassium titanate or mixed with organic substance, and polyamide elastomer layer It is intended to improve the adhesion. However, the PTFE intermediate layer containing solid particles mixed with the inorganic powder and the polyamide elastomer layer are in close contact with each other, and are not fused or bonded. The problem with reliability is not solved.

  On the other hand, the present inventors have already proposed a medical tube made of a polyimide resin and a fluororesin in Patent Document 3 for improving the slidability (lower friction) of the inner and outer surfaces of the medical tube. The medical tube is a medical tube in which a mixture of a polyimide resin and a fluororesin is heat-cured, and the fluororesin in the mixture is melted and deposited on the inner surface or inner and outer surfaces of the tube. The surface is a medical tube having low frictional resistance characteristics.

As disclosed in Patent Document 3, the present inventors formed a mixture of a fluororesin and a polyimide precursor into a tube shape, and converted the imide at a temperature equal to or higher than the melting point of the fluororesin so that the fluororesin became a polyimide. As a result of further research based on the phenomenon of melting and precipitating on the surface of the resin, an inner layer made of a fluororesin is formed in advance, and a mixed liquid of a polyimide precursor and a fluororesin is applied to the outer surface of the inner layer to By performing imide conversion at a temperature exceeding the melting point, it was found that the fluororesin deposited layer melted and precipitated from the inner layer and the polyimide resin can be strongly heat-sealed on the closely adhered surface, and the present invention has been completed.
JP 2003-340946 A JP 2000-051365 A JP 2005-205183 A

  The problem of the present invention is to solve many problems of the above-mentioned conventional technology, the friction resistance of the inner surface of the medical tube is small, and the inner fluororesin layer and the outer fluororesin mixed polyimide resin layer are firmly fused. In addition, an object of the present invention is to provide a medical tube that is safe for the human body as a material constituting the medical tube and has high reliability for the adhesiveness of the inner layer and the outer layer, and a method for manufacturing the same.

  That is, in order to achieve the above object, a medical tube according to claim 1 has an inner layer made of a fluororesin and an outer layer made of a mixture of a polyimide resin and a fluororesin on the outer surface of the inner layer. In this case, a part of the fluororesin in the outer layer is melted and deposited inside the outer layer, and is fused and integrated with the inner layer made of the fluororesin.

  The medical tube described in claim 2 is the polyimide precursor obtained by polymerizing the aromatic tetracarboxylic dianhydride and the aromatic diamine in an organic polar solvent in the invention described in claim 1. It is a polyimide resin obtained by heating and imidoconverting the body.

  The medical tube according to claim 3 is the medical tube according to claim 1, wherein the fluororesin is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), poly It is at least one selected from chlorotrifluoroethylene (PCTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (PETFE).

  The medical tube described in claim 4 is characterized in that, in the invention described in claim 1, the abundance of the fluororesin in the outer layer is 3 wt% or more and 50 wt% or less. To do.

  The medical tube manufacturing method according to claim 5 includes an inner layer forming step of forming an inner layer by coating the surface of a metal core wire with a fluororesin having a predetermined thickness, an aromatic tetracarboxylic dianhydride and an aromatic A polymerization step in which a diamine is polymerized in an organic polar solvent to prepare a polyimide precursor solution, and in the polyimide precursor solution, or a fluororesin is added during the polymerization step to obtain a mixed solution of the polyimide precursor and the fluororesin. A mixed liquid preparation step to be prepared; an application step in which the mixed liquid is applied to the outer surface of the inner layer at a predetermined thickness to produce a mixed liquid coating; and the maximum temperature of imide conversion of the mixed liquid coating is Characterized in that it comprises an imide conversion step of producing a multilayer composite by heating at a temperature exceeding the melting point of the fluororesin in the mixed solution, and a core wire removal step of extracting and removing the metal core wire from the multilayer composite. That.

  The medical tube of the present invention provides a medical tube that has an inner layer made of the most chemically stable fluororesin, is safe for the human body, has excellent releasability, and has extremely low frictional resistance on the inner surface of the tube. it can. In addition, since the outer layer has a configuration using a polyimide resin having excellent mechanical properties, a medical tube having a structure with a small outer diameter and a large inner diameter can be provided. Furthermore, by heating the inner layer and the outer layer made of a mixture of polyimide resin and fluororesin to a temperature equal to or higher than the melting point of the fluororesin, imide conversion can be performed to form a melted precipitation layer of the fluororesin, A highly reliable medical tube in which the inner layer and the outer layer are firmly fused and integrated can be provided. Moreover, according to the manufacturing method of the present invention, the process starts from the step of forming an inner layer made of a fluororesin on the outer surface of the metal core wire, and the polyimide precursor solution mixed with the fluororesin is applied to the outer surface until the step of imide conversion. Since it can be manufactured in a continuous line, it is possible to provide a method for manufacturing a medical tube with low cost and high accuracy.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an example of the medical tube of the present invention. The medical tube of the present invention has a multilayer structure of an inner layer 1 made of a fluororesin and an outer layer 2 made of a mixture of a polyimide resin and a fluororesin, and a part of the fluororesin 3 mixed in the outer layer 2 is A precipitate layer 4 is formed by melting inside the outer layer 2, and is firmly heat-sealed and integrated with the inner layer 1.

  Next, a phenomenon in which the above-described inner layer made of fluororesin and the outer layer made of a mixture of polyimide resin and fluororesin are fused and integrated will be described. When a mixture of polyimide precursor solution and fluororesin powder is formed into a tube or film and then heated to perform imide conversion, when the imide conversion temperature is below the melting point of the fluororesin, the fluororesin is polyimide resin It exists in a state of being mixed and dispersed in the layer. However, when heated to a temperature exceeding the melting point of the fluororesin, the fluororesin in the polyimide resin layer melts and is simultaneously extruded toward the outer surface of the polyimide resin by promoting the imide conversion of the polyimide precursor. A melt-deposited layer of fluororesin can be formed on the surface of the polyimide resin in a so-called sea-island structure in which the fluororesin exists in an island shape. Since the deposited layer and the outer surface of the fluororesin forming the inner layer are heated at the same temperature, the respective fluororesins can be firmly heat-sealed and integrated.

  Next, in the present invention, the polyimide resin is preferably a polyimide resin obtained by heating and imidoconverting a polyimide precursor obtained by polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent. . This is because when a polyimide precursor is used as a starting material, thin film processing is possible, a thin tube can be produced, and mechanical properties are excellent. In addition, the polyimide precursor is in the form of a solution, and the viscosity and solid content concentration can be easily changed. In the precursor solution, powder and fine particles such as fluororesin and colorant, or X-ray opaquer such as barium. This is because it is easy to mix them uniformly. Further, since it is in the form of a solution, it can be formed into various shapes, and a tube with high dimensional accuracy such as thickness and inner diameter can be produced.

  The polyimide precursor solution can be obtained by polymerizing approximately equimolar amounts of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent. Representative examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,3 ′, 4- Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8- Naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, perylene-3,4, 9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, and the like.

  Representative examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 1,5-diaminonaphthalene, 3,3'-dichlorobenzidine, 3,3'- Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-biphenyldiamine, 4,4'-diaminodiphenyl sulfide-3,3'-diaminodiphenylsulfone, benzidine, 3,3 ' -Dimethylbenzidine, 4,4'-diaminophenylsulfone, 4,4'-diaminodiphenylpropane, m-xylylenediamine, hexamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine and the like.

  These aromatic tetracarboxylic dianhydrides and aromatic diamines can be used alone or in combination. Moreover, it is also possible to complete the polyimide precursor solution and use it by mixing these precursor solutions.

  Examples of the organic polar solvent for polymerizing the aromatic tetracarboxylic dianhydride and the aromatic diamine include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide. N, N-diethylacetamide, dimethyl sulfoxide, hexamethyl phosphortriamide, pyridine, dimethyltetramethylene sulfone, tetramethylene sulfone, propylene carbonate, γ-butyrolactone, and the like. These solvents can be used alone or in combination. Are preferably used.

  The polyimide precursor solution is obtained by polymerizing the aromatic tetracarboxylic dianhydride and the aromatic diamine in an organic polar solvent, usually at 90 ° C. or less, and the solid content in the solvent is produced. Although it can be set according to the shape and processing conditions of the polyimide tube, it is 10 to 50% by weight.

  In addition, when an aromatic tetracarboxylic dianhydride and an aromatic diamine are polymerized in an organic polar solvent, the viscosity of the solution increases depending on the polymerization status. Can do. It is usually used at a viscosity of 1 to 5000 poise depending on manufacturing conditions and working conditions. A more preferred solution viscosity is in the range of 10 to 1500 poise. In addition, the polyimide precursor solution of the present invention includes an agent for improving mechanical properties such as an imidizing agent, and a contrast agent powder such as barium sulfate for confirming the state of movement of a catheter inserted into the body by X-rays. Is preferably added.

  Next, in the present invention, two fluororesins are used: a fluororesin used for molding the inner layer of the tube, and a fluororesin used for molding the outer layer of the tube by mixing in the polyimide precursor solution. There is no need to specifically limit the fluororesin, such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-hexafluoropropylene. It is preferably at least one selected from a copolymer (FEP) and a tetrafluoroethylene-ethylene copolymer (PETFE). In the present invention, more preferred fluororesins are PTFE, PFA, and FEP. This is because these fluororesins are chemically inert, have high heat resistance, and are safe and reliable as medical materials.

  Next, in the present invention, the form of the fluororesin material for forming the inner layer of the medical tube is preferably a fluororesin aqueous dispersion (dispersion) or a solution dispersion. The fluororesin aqueous dispersion is, for example, an aqueous dispersion of fluororesin particles produced by a method such as emulsion polymerization of a fluoromonomer and dispersed in water in a form in which the fluororesin particles are covered with a surfactant. Goods can be used. The fluororesin aqueous dispersion can be coated on the surface of a metal core wire by a method such as dipping, and can be used as an inner layer material of a medical tube by drying and firing.

  Further, as a material form other than the fluororesin dispersion, a powdered fluororesin can be used. These fluororesin powders can be used as an inner layer of a medical tube after being molded on the surface of the core wire by an electrostatic coating method or the like and then heated and fired.

  Further, powders and pellets of thermoplastic fluororesin such as PFA and FEP can be molded to a predetermined thickness on the surface of the core wire by a melt extrusion molding method, and can be used as an inner layer material of a medical tube.

  Next, the form of the fluororesin material mixed in the polyimide precursor solution is preferably a powder. It is because it is easy to disperse | distribute uniformly when mixing with a polyimide precursor solution that it is a powder form. The average particle diameter of the fluororesin powder is preferably in the range of 0.1 to 50 μm. A more preferable range is 1.0 to 30 μm. This is because within such a range, the powder is less aggregated and can be uniformly dispersed. If the average particle size is less than 0.1 μm, the particles are likely to agglomerate, and if it exceeds 50 μm, irregularities due to the fluororesin particles are likely to occur on the inner surface or outer surface of the tube. In addition, the measurement method of the average particle diameter of the said fluororesin powder is a laser diffraction type particle size distribution measuring device (SALD-2100: manufactured by Shimadzu Corporation) or a laser diffraction / scattering type particle size distribution measuring device (LA-920: Horiba). Can be measured by a manufacturing company

Next, in the present invention, the mixing amount of the fluororesin mixed in the polyimide precursor solution is preferably in the range of 3 wt% or more and 50 wt% or less with respect to the solid content weight of the polyimide precursor solution. . Especially preferably, it is 10 to 30 weight%. When the mixing amount is 3% by weight or less, the amount of the fluororesin that melts and precipitates is small, and it is difficult to obtain the fusion force with the fluororesin of the inner layer, and when it is 50% by weight or more, the polyimide resin The mechanical strength of the outer layer is lowered, and at the same time, the smoothness of the polyimide resin surface is impaired, and cracks are likely to occur.

  Next, in the structure of an example of the medical tube of the present invention, the polyimide shown in FIG. 1 is used to form the outer layer of the medical tube using a polyimide precursor solution in which a fluorine resin is mixed in the polyimide precursor solution. The fluororesin melts and precipitates also on the outer surface 5 of the outer layer 2 made of a mixture of resin and fluororesin, and in the medical tube of the present invention, the inner surface and the outermost surface 5 are also excellent in releasability, friction resistance Low medical tubes.

  Next, when the outer surface of the medical tube of the present invention is further coated with a material such as silicone rubber or nylon, if the fluororesin is deposited on the surface of the outermost surface 5 of the medical tube described above, silicone rubber or the like Adhesive strength with the coating material will be reduced. To solve such a problem, a polyimide precursor solution mixed with a fluororesin is applied to the outer surface of the inner layer made of a fluororesin, and heat-treated at a temperature lower than the melting point of the mixed fluororesin, so that a tube intermediate is obtained. And coating the outer surface of the intermediate body with a solution consisting of a single polyimide precursor at a predetermined thickness, and then heating the maximum temperature of imide conversion at a temperature exceeding the melting point of the mixed fluororesin, thereby forming the outer layer 2. It is preferable to use a medical tube having a three-layer structure shown in FIG.

  A three-layered medical tube having the polyimide resin single layer 6 can improve adhesion even when coated with a material such as silicone rubber, urethane resin, nylon, polyethylene, polypropylene, vinyl chloride. In addition, these composite tubes can be used as catheters or endoscope tubes.

  The medical tube of the present invention can be manufactured, for example, by the following method. An inner layer made of a fluororesin is formed with a predetermined thickness on the surface of a metal core wire having a predetermined outer diameter (a diameter corresponding to the inner diameter of the tube).

  Next, aromatic tetracarboxylic dianhydride and aromatic diamine are polymerized in an organic polar solvent to obtain a polyimide precursor solution, and a fluorine resin is added in the polyimide precursor solution or in the polymerization step to obtain a polyimide precursor. Prepare a mixture of body and fluororesin. The mixed liquid is applied to the outer surface of the inner layer made of the fluororesin with a predetermined thickness to produce a mixed liquid coated product.

  Thereafter, heat treatment is performed at a temperature exceeding the melting point of the fluororesin in the mixed solution at the maximum temperature of imide conversion, and then only the metal core wire is stretched and the outer diameter is reduced, and the metal core wire is pulled out. Can be manufactured. In the medical tube manufacturing method of the present invention, the inner surface of the tube is formed of a single fluororesin, so that the core wire can be easily extracted.

  In the production method of the present invention, the method for forming the inner layer made of a fluororesin is preferably a method in which a fluororesin dispersion is formed on the surface of the metal core wire by a dipping method and then dried and fired. This is because the dipping method has less material loss than spray coating or the like, and the dispersion viscosity and the like can be easily managed in the process.

  When the fluororesin dispersion is repeatedly applied to a predetermined thickness, after dipping the fluororesin dispersion, first, heat treatment is performed at a temperature not higher than the melting point of the fluororesin, and the dipping and heat treatment are repeated until the predetermined thickness is reached. A method of finally heating to a temperature equal to or higher than the melting point of the fluororesin and then baking is preferable because there is no generation of repellency of the fluororesin dispersion during overcoating.

  Next, when applying a mixture of a fluororesin and a polyimide precursor solution to the outer surface of the inner layer made of fluororesin, the inner layer fluororesin is unfired (heat-treated at a temperature not higher than the melting point of the fluororesin). It is preferable to apply the mixed solution on the surface in a state because it can prevent repellency of the mixed solution. Furthermore, after the inner layer is completely baked and formed, the surface of the fluororesin may be modified by corona discharge or the like, and a polyimide precursor solution may be applied.

  In the production method of the present invention, in order to fuse the inner layer made of the fluororesin and the fluororesin mixed in the polyimide resin outer layer, it is necessary to heat at a temperature exceeding the melting point of the fluororesin in the outer layer. It is preferable to complete the imide conversion at a temperature higher than the melting point of the fluororesin by 10 to 15 ° C. or higher. The heating time is preferably within 30 minutes after reaching the temperature at which the maximum temperature of imide conversion exceeds the melting point of the fluororesin. If it is longer than 30 minutes, the thermal decomposition of the fluororesin and the mechanical properties of the polyimide resin may be reduced.

  As the metal core wire used in the production method of the present invention, an alloy wire, stainless steel wire, silver-plated annealed copper wire or the like can be used. The metal core wire is not limited as long as it does not deteriorate at the imide conversion temperature near 400 ° C., and the stainless steel or silver-plated annealed copper wire is a more preferable material.

Hereinafter, the present invention will be described in more detail based on examples.
Example 1
A stainless steel wire having an outer diameter of 0.55 mm was used as a core wire, and this core wire was dipped in a PTFE resin dispersion (AD-912 manufactured by Asahi Glass Co., Ltd.), pulled up, and dried at a temperature of 200 to 300 ° C. This dipping and drying process was continuously repeated 5 times to prepare a PTFE resin-coated wire in which the surface of the stainless steel core wire was coated with PTFE resin. The outer diameter of the coated wire was 0.564 mm. This PTFE resin coating layer forms the inner layer of a medical tube.

  Next, (PireML, RC-5063, manufactured by IST) was prepared as a polyimide precursor solution. This polyimide precursor solution is a solution obtained by polymerizing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methyl-2-pyrrolidone. The rotational viscosity with a B-type viscometer was 50 poise. The solid content in the polyimide precursor solution was 17.5% by weight. Fluorine resin powder having an average particle size of 3.0 μm (PTFE resin: melting point 327 ° C: trade name “ZONYL MP1200” manufactured by DuPont) in the polyimide precursor solution was 25% by weight based on the solid content in the polyimide precursor solution. It added so that it might become a ratio, it stirred, and was disperse | distributed uniformly. Thereafter, coarse foreign matters were filtered using a 250 mesh stainless steel wire mesh to prepare a mixed liquid of fluororesin powder and polyimide precursor.

  Next, the PTFE resin-coated wire is dipped in the mixed solution and pulled up, and a coating film is uniformly formed on the surface using a die, and then passed through a furnace at 150 to 200 ° C. to perform an initial imide conversion treatment. Went. After the coating film formation step and the initial imidization step of this mixed solution were repeated six times in succession, the final imide conversion treatment was performed by heating at a temperature of 350 to 400 ° C. for 7 minutes, and the outer surface of the PTFE resin-coated wire A coated wire (referred to as F-PIF coated wire) having an outer diameter of 0.725 mm coated with a mixture of a fluororesin and a polyimide resin was prepared.

  Next, the (F-PIF coated wire) is cut to a length of 2 m, the both ends of the stainless steel core wire are gripped and stretched so as not to break, the outer diameter is reduced, the stainless steel core wire is pulled out, and the inner diameter is 0. A medical tube having a diameter of 55 mm and an outer diameter of 0.725 mm was produced. This medical tube is a medical tube whose inner layer is formed of pure PTFE resin alone and whose outer surface is made of a polyimide resin mixed with fluororesin powder, and whose inner surface has the low frictional resistance that PTFE resin has. Was. Further, the inner layer and the outer layer were firmly fused by the fluororesin deposited layer melted and precipitated from the polyimide resin, and could not be peeled off. In addition, this medical tube has a characteristic that the inner surface and the outer surface of the medical tube have low frictional resistance because the fluororesin is melted and deposited on the outer surface of the outer layer (portion 5 in FIG. 1). .

(Example 2)
In Example 1, as a fluororesin mixed with the polyimide precursor solution, FEP resin powder having an average particle size of 14 μm (trade name “532-8110” manufactured by DuPont) is 20% by weight based on the solid content in the polyimide precursor solution. A medical tube was produced under the same conditions as in Example 1 except that the final imidization temperature was changed to 330 to 370 ° C. using the mixed solution added so as to have the ratio of This tube has an inner diameter of 0.55 mm and an outer diameter of 0.715 mm, and the inner layer has a low coefficient of friction of PTFE resin alone, and the inner layer and the outer layer are firmly bonded with a deposited layer in which the FEP resin has melted and deposited. And could not be peeled off. Also, the FEP resin melted and deposited on the outer surface of the outer layer (the portion 5 in FIG. 1), and a medical tube having a low frictional resistance was obtained.

(Example 3)
A medical tube was produced under the same conditions as in Example 1 except that the inner layer material made of fluororesin in Example 1 was changed to PFA resin dispersion (PFA920HP Plus manufactured by DuPont). The inner diameter of this tube is 0.55 mm, the outer diameter is 0.720 mm, the inner layer has a low coefficient of friction of PFA resin fat alone, and the inner layer and the outer layer are firmly fused with a deposited layer of PTFE resin melted and precipitated. , Could not be peeled. In addition, PTFE resin melted and deposited on the outer surface of the polyimide outer layer (portion 5 in FIG. 1), and a medical tube having a low frictional resistance was obtained.

Example 4
A PTFE resin-coated wire as an inner layer was molded under the same conditions as in Example 1. Thereafter, using the mixed solution prepared in Example 1, the coating film forming step of the mixed solution and the initial imidization step were repeated 6 times on the outer surface of the PTFE resin-coated wire under the same conditions as in Example 1, The polyimide precursor solution (PyreML, RC-5019 manufactured by IST) alone was applied to the outer surface with a thickness of about 30 μm, and after initial imidization treatment, heated at a temperature of 350 to 400 ° C. for 7 minutes. A final imidation conversion treatment is carried out, and the inner layer is a PTFE resin, the outer layer is a polyimide resin intermediate layer mixed with fluororesin powder, and the outer surface is coated with a single layer of polyimide resin (F- (Referred to as PIF-PI coated wire). Thereafter, the F-PIF-PI-coated wire was cut to 2 m, the diameter of the stainless steel wire was reduced, and a three-layered medical tube was obtained. This tube has an outer diameter of 0.731 mm, an inner diameter of 0.55 mm, an inner fluororesin layer thickness of about 6 μm, an outer layer thickness of about 81 μm, and an outermost polyimide single layer (6 in FIG. 2) of about 5 μm. there were. The inner surface of this tube had the low friction property of PTFE resin, and the layers of the three-layer structure were firmly fused and could not be integrated and separated. In addition, the fluororesin is not deposited on the surface of the polyimide resin single layer (6 in FIG. 2) and has a general polyimide film characteristic. When this outer surface is covered with silicone rubber, sufficient adhesion is obtained. It was.

(Example 5)
Example 1 except that a silver-plated copper wire having an outer diameter of 0.57 mm was used, and an inner layer obtained by extruding and coating a PFA resin (PFA940HP Plus manufactured by DuPont) at a thickness of 150 μm with a melt extrusion molding machine on the outer surface thereof. A medical tube was produced under the conditions. The inner surface of this tube had the low frictional resistance of the PFA resin, and the inner layer and the outer layer were firmly fused with the deposited layer of PTFE resin and could not be peeled off.

(Comparative Example 1)
A medical tube was prepared under the same conditions as in Example 1 except that the amount of the fluororesin powder mixed in the polyimide precursor solution in Example 1 was set to 2% by weight with respect to the solid content in the polyimide precursor solution. Produced. Although the inner surface of this tube had the low frictional resistance of PTFE resin, the inner layer and the outer layer could be easily peeled off, and the use of the medical tube was unreliable.

  The medical tube of the present invention is a medical tube member such as a catheter or an endoscope, or a coated tube for electrical insulation, and the inner layer is made of pure fluororesin. Can be used for highly corrosive chemicals and solvent transport tubes.

It is a schematic cross section of the medical tube produced in Example 1 of the present invention. It is a schematic cross section of the medical tube which outermost layer consists of a polyimide resin single | mono layer layer with the 3 layer structure produced in Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner layer which consists of a fluororesin 2 Outer layer which consists of a mixture of a polyimide resin and a foot-layer resin 3 The fluororesin mixed in the outer layer 4 The melt precipitation layer of the inner surface of the outer layer of the fluororesin mixed in the outer layer 5 The mixture in the outer layer Melted and deposited layer on the outer surface of the outer layer of fluororesin 6 Polyimide resin single layer

Claims (5)

  A medical tube having an inner layer made of a fluororesin and an outer layer made of a mixture of a polyimide resin and a fluororesin on the outer surface of the inner layer, wherein a part of the fluororesin in the outer layer is melted inside the outer layer. The medical tube, wherein the deposited layer is fused and integrated with the inner layer made of the fluororesin.   The polyimide resin is a polyimide resin obtained by heating and imidoconverting a polyimide precursor obtained by polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent. The medical tube described.   The fluororesin is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), The medical tube according to claim 1, wherein the medical tube is at least one selected from tetrafluoroethylene-ethylene copolymer (PETFE).   The medical tube according to claim 1, wherein the amount of the fluororesin in the outer layer is 3 wt% or more and 50 wt% or less.   An inner layer forming step of forming the inner layer by coating the surface of the metal core wire with a fluororesin having a predetermined thickness, and a polyimide precursor solution by polymerizing aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent A polymerization step for preparing a mixture, a mixed solution preparation step for preparing a mixed solution of a polyimide precursor and a fluororesin by adding a fluororesin in the polyimide precursor solution or during the polymerization step, and the mixed solution in the inner layer A coating step of applying a predetermined thickness to the outer surface of the substrate to prepare a mixed liquid coating, and heating the mixed liquid coating at a temperature at which the maximum temperature of imide conversion exceeds the melting point of the fluororesin in the mixed liquid A method for producing a medical tube, comprising: an imide conversion step for producing a multilayer composite; and a core wire removal step for extracting and removing a metal core wire from the multilayer composite.

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