Thermoplastic fluorine resin pipe

Abstract

The present invention provides a thermoplastic fluorine-containing resin tube suitable for manufacturing a catheter, which can suppress the formation of gaps or bubbles at the joint of the catheter during the manufacture of the catheter. The thermoplastic fluorine-containing resin tube has tear resistance in the longitudinal direction and has a thermal expansion coefficient of 0% or more in the longitudinal direction after heating in a gas phase at a temperature of 100° C. for 5 minutes.

Description

[0001] (This application is a divisional application of application No. 201880085223.9, filed on July 5, 2018, entitled “Thermoplastic fluorinated resin tube”) Technical Field

[0002] The present invention relates to a thermoplastic fluorine-containing resin tube having tearability and useful in the production of a catheter, and a method for producing the same. Background Art

[0003] In the prior art, pre-coated tubes are widely used in various products such as electric wires, lead wires, catheters, and wires. These products are temporarily coated and removed from the products after the intended purpose is achieved. Such pre-coated tubes are usually made of synthetic resins, synthetic rubbers, and the like.

[0004] Although synthetic resins and synthetic rubbers have excellent product protection properties, they require a large tearing force to be removed from the product. Therefore, there are problems such as difficulty in tearing by hand, a long time required for removal, and a large force applied to the product during tearing, which may damage the product. In addition, there is also a method of scratching the tube with a knife or the like and then tearing it, but the knife or the like may scratch the product located inside the coating tube.

[0005] As a technology for solving such a problem, for example, Patent Document 1 discloses a tearable fluororesin tube made of a plurality of different types of fluororesins. In addition, Patent Document 2 describes a tearable and transparent fluororesin tube in which PTFE particles are dispersed in a thermoplastic fluororesin. However, these fluororesin tubes are all given tearability by blending other fluororesins into the main fluororesin, and therefore have the disadvantages that the heat shrinkage rate decreases and the transparency also decreases as the amount of other fluororesins added increases.

[0006] In this regard, for example, Patent Document 3 discloses a fluorine-containing resin tube having tearability, transparency, and high shrinkage using one thermoplastic fluorine-containing resin. The fluorine-containing resin tube disclosed in Patent Document 3 has the advantages of high shrinkage and high transparency compared to the fluorine-containing resin tubes disclosed in Patent Documents 1 and 2.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 4968823

[0010] Patent Document 2: International Publication No. 2016 / 204174

[0011] Patent Document 3: International Publication No. 2017 / 043317 Summary of the invention

[0012] Technical problem to be solved by the invention

[0013] As described above, for example, Patent Documents 1 to 3 disclose fluorine-containing resin tubes that have tear properties and can be used as pre-coating tubes when manufacturing catheters, etc. The inventors of the present invention have repeatedly studied the manufacture of catheters using the conventional fluorine-containing resin tubes disclosed in Patent Documents 1 to 3.

[0014] like Figure 1 As shown in FIG. 1 , the following method is generally used in the manufacturing process of the catheter: the periphery of the core 20 composed of the metal core wire is covered with the thermoplastic resin tubes 30 and 31 (such as nylon elastomer tubes, etc.) constituting the catheter, and then covered from the outside with the heat shrinkable tube 10. In this state, they are conveyed in one direction x1 and passed through the heating unit 40 (about 200° C.), thereby causing the inner diameter of the heat shrinkable tube 10 to shrink by heat, and the thermoplastic resin tubes 30 and 31 to melt and adhere to the core. Figure 1 As shown, in the thermoplastic resin tube constituting the catheter, for example, the portion held by the doctor's hand and the portion inserted into the patient's body are formed of different materials, so multiple tubes such as thermoplastic resin tube 30 and thermoplastic resin tube 31, which are made of thermoplastic resins different from each other (for example, different hardness), are used.

[0015] However, in the manufacturing process of such catheters, Figure 1 As shown in the figure, the joint portion P of the thermoplastic resin tube 30 and the thermoplastic resin tube 31 is joined by melting when passing through the heating unit 40, and before that, they are in contact with each other but not joined. Therefore, the following new problem is found: when the inner diameter of the heat shrinkable tube 10 is heat-shrunk in the heating unit 40, a gap is generated in the joint portion P of the thermoplastic resin tube 30 and the thermoplastic resin tube 31. If they are melted and joined in this state, a gap or air bubble may be formed in the joint portion P of the conduit.

[0016] It is known that conventional fluorine-containing resin tubes disclosed in Patent Documents 1 to 3, for example, all have such a problem when the inner diameter is thermally contracted.

[0017] Under such circumstances, the main object of the present invention is to provide a thermoplastic fluorine-containing resin tube suitable for manufacturing a catheter, which can suppress the formation of gaps or bubbles at the joints of the catheter during the manufacture of the catheter. Another object of the present invention is to provide a method for manufacturing the thermoplastic fluorine-containing resin tube.

[0018] Technical means for solving technical problems

[0019] In order to solve the above technical problems, the inventors of the present invention conducted intensive research and found that the formation of gaps or bubbles in the joints of the catheter is closely related to the shrinkage characteristics of the thermoplastic fluorine resin tube in the longitudinal direction. After further research, a thermoplastic fluorine resin tube was found that has tearability in the longitudinal direction and a thermal expansion coefficient in the longitudinal direction of 0% or more after heating in a gas phase at a temperature of 100°C for 5 minutes. The thermoplastic fluorine resin tube can suppress the formation of gaps or bubbles in the joints of the catheter when manufacturing the catheter, and is suitable for manufacturing the catheter. The present invention was completed based on such knowledge and further repeated research.

[0020] That is, the present invention provides the following inventions.

[0021] Item 1. A thermoplastic fluorine-containing resin tube having tearability in the longitudinal direction and having a thermal expansion coefficient in the longitudinal direction of 0% or more when heated in a gas phase at a temperature of 100°C for 5 minutes.

[0022] Item 2. The thermoplastic fluorine-containing resin tube according to Item 1, wherein the heat shrinkage of the inner diameter after heating in a gas phase at a temperature of 200° C. for 5 minutes is 40% or more.

[0023] Item 3. The thermoplastic fluorine-containing resin tube according to Item 1 or 2, wherein the thermoplastic fluorine-containing resin is formed of at least one of a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

[0024] Item 4. The thermoplastic fluorine-containing resin tube according to any one of Items 1 to 3, wherein the coefficient of thermal expansion in the longitudinal direction after heating at 100° C. for 5 minutes is 0 to 4%.

[0025] Item 5. The thermoplastic fluorine-containing resin tube according to any one of Items 1 to 4, which has a weld mark in the longitudinal direction.

[0026] Item 6. A method for producing a thermoplastic fluorine-containing resin tube, for producing the fluorine-containing resin tube according to any one of Items 1 to 5, the method comprising:

[0027] A step of melt-extruding a thermoplastic fluorine-containing resin to obtain a raw tube for a thermoplastic fluorine-containing resin tube; and

[0028] The step of heating the shell tube to expand the inner diameter of the shell tube while keeping the shell tube temperature below 140°C.

[0029] Effects of the Invention

[0030] According to the present invention, it is possible to provide a thermoplastic fluorine-containing resin tube suitable for manufacturing a tube, which can suppress the formation of gaps or bubbles at the joint of the tube when manufacturing the tube. In addition, according to the present invention, it is possible to provide a method for manufacturing the thermoplastic fluorine-containing resin tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram for explaining a method for producing a catheter using a heat shrinkable tube.

[0032] Figure 2 It is a schematic cross-sectional view of an example of a die used for melt extrusion molding in the method for producing a fluorine-containing resin tube of the present invention (a cross section in a direction perpendicular to the melt extrusion direction, a portion where a leg portion exists). DETAILED DESCRIPTION

[0033] 1. Thermoplastic fluorine-containing resin pipe

[0034] The thermoplastic fluorine-containing resin tube of the present invention is characterized in that it has tearability in the longitudinal direction and has a thermal expansion coefficient of 0% or more in the longitudinal direction after heating in a gas phase at a temperature of 100° C. for 5 minutes. The thermoplastic fluorine-containing resin tube of the present invention has such characteristics that when manufacturing a catheter, the formation of gaps or bubbles in the joint of the catheter can be suppressed, and is suitable for use in the manufacture of the catheter.

[0035] More specifically, as described above, in the thermoplastic resin tube constituting the catheter, Figure 1As shown in the figure, for example, the part held by the doctor and the part inserted into the patient's body are formed of different materials, so a plurality of tubes made of different thermoplastic resins (for example, different hardness) such as the thermoplastic resin tube 30 and the thermoplastic resin tube 31 are used. Then, the joint P of the thermoplastic resin tube 30 and the thermoplastic resin tube 31 is joined by melting when passing through the heating unit 40, and before that, they are in contact but not joined. Therefore, when the conventional heat shrinkable tube is used to manufacture the catheter, when the inner diameter of the heating unit 40 is thermally shrunk, a gap is generated in the joint P of the thermoplastic resin tube 30 and the thermoplastic resin tube 31. If they are melted and joined in this state, a gap or air bubble may be formed in the joint P of the catheter. In contrast, the thermoplastic fluorine-containing resin tube of the present invention has a characteristic that the coefficient of thermal expansion in the longitudinal direction is 0% or more in a low temperature region at the initial stage of thermal shrinkage of the inner diameter of the thermoplastic fluorine-containing resin tube at a temperature of 100°C (i.e., it does not shrink in the longitudinal direction or expands in the longitudinal direction at 100°C), and when the thermoplastic shrinkable tube of the present invention is used to manufacture a catheter, gaps or bubbles are less likely to be formed in the joint P. It is presumed that this is because, when the heat-shrinkable tube has shrinkage in the longitudinal direction x1 as in the prior art, the thermoplastic resin tube 30 is pulled together due to its shrinkage characteristics, thereby generating voids in the joint P, while in the thermoplastic fluorine-containing resin tube of the present invention, since it does not shrink in the longitudinal direction or expand in the longitudinal direction at 100°C, the thermoplastic resin tube 30 is not pulled together, and the generation of voids in the joint P can be effectively suppressed. Specifically, when the thermal expansion coefficient in the longitudinal direction exceeds 0%, the thermoplastic resin tube 30 on the side close to the heating portion 40 is pushed to the side opposite to the heating portion 40, so that the joint P of the thermoplastic resin tube 30 and the thermoplastic resin tube 31 can be joined by melting in a state where the joint P is reliably in contact. Therefore, it is presumed that the formation of gaps or bubbles in the joint P of the conduit can be effectively suppressed.

[0036] In the thermoplastic fluororesin tube of the present invention, from the viewpoint of effectively suppressing the formation of gaps or bubbles at the joints of the tube when manufacturing the tube, the thermal expansion coefficient in the longitudinal direction after heating at a temperature of 100° C. for 5 minutes is preferably 0 to 4%, more preferably more than 0% and 4% or less, and further preferably 0.3 to 4%.

[0037] The thermoplastic fluorine-containing resin tube of the present invention is formed of a thermoplastic fluorine-containing resin. The thermoplastic fluorine-containing resin is preferably a resin that can be molded into a tube by melt extrusion at a temperature of about 260 to 450°C, preferably about 280 to 420°C.

[0038] As specific examples of thermoplastic fluorine-containing resins, tetrafluoroethylene-hexafluoropropylene copolymers (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA), tetrafluoroethylene-ethylene copolymers (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymers (ECTFE), polyvinylidene fluoride (PVDF), etc. are preferably cited, but are not limited to these. Among these, from the perspective of exerting particularly excellent tearing properties and making the thermal expansion coefficient in the longitudinal direction at a temperature of 100°C 0%, and being suitable for manufacturing catheters, tetrafluoroethylene-hexafluoropropylene copolymers (FEP) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA) are preferably cited. Thermoplastic fluorine-containing resins can be used only one type, or two or more types can be mixed and used. In addition, these copolymers can also be ternary copolymers, for example. For example, as a ternary copolymer of tetrafluoroethylene-hexafluoropropylene copolymer (FEP), a copolymer formed by copolymerizing with perfluoroalkyl vinyl ether in addition to tetrafluoroethylene and hexafluoropropylene can be cited (tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEP)).

[0039] In the thermoplastic fluororesin tube of the present invention, from the viewpoint of effectively suppressing the formation of gaps or bubbles at the joint of the catheter and improving the transparency of the thermoplastic fluororesin tube, the thermoplastic fluororesin tube of the present invention is preferably formed of a thermoplastic fluororesin other than polytetrafluoroethylene, particularly preferably formed of a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and further preferably a tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer.

[0040] The thermoplastic fluororesin tube of the present invention has heat shrinkage in the radial direction. The heat shrinkage of the inner diameter of the thermoplastic fluororesin tube can be appropriately imparted by, for example, applying pressure from the inside while the original tube of the thermoplastic fluororesin tube is heated to expand the inner diameter. For example, when using the thermoplastic fluororesin tube of the present invention to cover (pre-cover) parts of a catheter, these parts are inserted into the thermoplastic fluororesin tube having heat shrinkage to heat shrink the thermoplastic fluororesin tube, so that the catheter can be appropriately manufactured, and the thermoplastic fluororesin tube is covered so that the catheter is appropriately fitted. As a thermoplastic fluororesin constituting the thermoplastic fluororesin tube of the present invention, for example, tetrafluoroethylene-hexafluoropropylene copolymer or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is used, and further, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer is used, which can exert particularly excellent heat shrinkage on the inner diameter.

[0041] The heat shrinkage of the thermoplastic fluorine-containing resin tube of the present invention is not particularly limited, but the heat shrinkage of the inner diameter after heating at 200° C. in a gas phase (specifically, in air) for 5 minutes is preferably 40% or more, more preferably about 40 to 60%. Therefore, it is suitable for use in the production of catheters.

[0042] In addition, as described above, the thermoplastic fluorine-containing resin tube of the present invention has a characteristic that the thermal expansion coefficient in the longitudinal direction is 0% or more in the low temperature region at the initial stage of thermal contraction of the inner diameter of the thermoplastic fluorine-containing resin tube such as at a temperature of 100°C (i.e., it does not contract or expands in the longitudinal direction at 100°C), so the thermoplastic resin tube 30 near the heating section 40 side is not pulled toward the heating section 40 side. In the thermoplastic fluorine-containing resin tube of the present invention, the thermal contraction coefficient of the inner diameter after heating in a gas phase (specifically, in air) at 100°C for 5 minutes is preferably about 10 to 30%, and more preferably about 10 to 20%.

[0043] The melt flow rate (MFR) of the thermoplastic fluororesin constituting the thermoplastic fluororesin tube of the present invention is not particularly limited, but is preferably about 1 to 25 from the viewpoint of improving the tear resistance of the thermoplastic fluororesin tube and also improving the heat shrinkage of the inner diameter. In the present invention, the MFR of the thermoplastic fluororesin is a value measured according to the method specified in JIS K7210:1999.

[0044] The thermoplastic fluorine-containing resin tube of the present invention is formed of one thermoplastic fluorine-containing resin (but excluding polytetrafluoroethylene), and thus can exhibit excellent tearing properties and can also exhibit excellent heat shrinkage of the inner diameter. The detailed mechanism by which the thermoplastic fluorine-containing resin tube of the present invention can exhibit excellent tearing properties and excellent heat shrinkage of the inner diameter can be considered as follows. That is, it can be considered that when the thermoplastic fluorine-containing resin tube of the present invention is formed of one thermoplastic fluorine-containing resin, the fluorine-containing resin constituting the tube does not phase separate, and the entire tube has tearing properties and heat shrinkage properties with high uniformity, resulting in a tube with excellent properties.

[0045] In addition, the thermoplastic fluorine-containing resin tube of the present invention is formed by one kind of thermoplastic fluorine-containing resin, and thus can also exert high transparency. That is, the thermoplastic fluorine-containing resin tube of the present invention can be made into a transparent thermoplastic fluorine-containing resin tube. Products such as catheters coated with the thermoplastic fluorine-containing resin tube of the present invention are required to be arranged in the tube with high positional accuracy when using the tube for coating. At this time, by using the thermoplastic fluorine-containing resin tube of the present invention with high transparency, it can be easily arranged in the tube with high positional accuracy. On the other hand, when using a tube obtained by melt-extruding and molding a plurality of thermoplastic fluorine-containing resins of different types into a tubular shape, or a tube obtained by using polytetrafluoroethylene, the transparency of the tube is low, a white turbidity phenomenon occurs, and it is difficult to be arranged in the tube with high positional accuracy. Among them, in the present invention, a transparent thermoplastic fluorine-containing resin tube means a tube evaluated as having high transparency in the evaluation of transparency described in the embodiment.

[0046] In the thermoplastic fluororesin pipe of the present invention, the so-called "one kind of thermoplastic fluororesin" can be one kind of thermoplastic fluororesin from the viewpoint of suppressing phase separation, ensuring inner surface smoothness and transparency, and imparting high tear resistance and shrinkage force. For example, it can be a resin with different weight average molecular weight or polymerization form (such as block polymer, random polymer, etc.), or a mixed resin of resins with different polymerization ratios of multiple monomers. That is, for example, even if the "one kind of thermoplastic fluororesin" contains resins with different weight average molecular weight or polymerization form, or thermoplastic resins with different polymerization ratios of multiple monomers, as long as the type of thermoplastic fluororesin is one, phase separation can be suppressed, and thus a thermoplastic fluororesin pipe with excellent tear resistance can be made. However, as mentioned above, since polytetrafluoroethylene has the problem of poor tear resistance, it is not substantially included in the "one kind of thermoplastic fluororesin" of the present invention.

[0047] However, in the present invention, one kind of thermoplastic fluorine-containing resin may not be entirely composed of only one kind of thermoplastic fluorine-containing resin as long as the effect of the present invention can be exerted, and it is sufficient that it is substantially composed of one kind of thermoplastic fluorine-containing resin.

[0048] When the thermoplastic fluororesin tube of the present invention is formed of two or more thermoplastic fluororesins, for example, preferably one thermoplastic fluororesin is 90% by mass or more and the other thermoplastic fluororesins are 10% by mass or less, and more preferably one thermoplastic fluororesin is 98% by mass or more and the other thermoplastic fluororesins are 2% by mass or less. Thus, the transparency of the thermoplastic fluororesin tube of the present invention can be improved.

[0049] Furthermore, the thermoplastic fluorine-containing resin tube of the present invention may contain a filler or the like in addition to one type of thermoplastic fluorine-containing resin.

[0050] In the thermoplastic fluorine-containing resin tube of the present invention, the proportion of volatile components generated after heating at 400°C for 1 hour is preferably 0.2 mass % or less.

[0051] The thermoplastic fluororesin tube of the present invention is preferably a tube in which the inner diameter (and outer diameter) is expanded by pressurizing an original tube formed into a tubular shape by melt extrusion of a thermoplastic fluororesin in a heated state from the inside. Thus, when manufacturing a catheter, it is possible to easily insert components such as a core and a thermoplastic resin tube constituting the catheter into the thermoplastic fluororesin tube of the present invention. In addition, since the thermoplastic fluororesin tube of the present invention has heat shrinkability, the thermoplastic fluororesin tube of the present invention can be appropriately fitted with the components of the catheter by heat shrinking it so that the catheter is covered. Among them, as a specific method for expanding the inner diameter of the original tube in the thermoplastic fluororesin tube of the present invention, as described below, for example, a method of pressurizing the original tube from the inside of the original tube using pressurized nitrogen or the like while the original tube is heated to below 140°C can be cited. In the prior art, the temperature for expanding the inner diameter of the raw tube is generally about 150 to 160°C, but in the present invention, the temperature of the raw tube when expanding the raw tube is set to less than 140°C in order to shrink the inner diameter and expand more than 0% in the longitudinal direction at 100°C. Although this is not intended to be limiting, it is presumed that by setting the temperature of the raw tube when expanding the raw tube to less than 140°C, the expansion of the raw tube proceeds slowly over time, and the molecular orientation in the longitudinal direction formed during the melt extrusion molding of the raw tube is easily relaxed, so that the expansion in the longitudinal direction at 100°C is 0% or more. The thermoplastic fluorine-containing resin tube of the present invention obtained by expanding the inner diameter of the raw tube has improved heat shrinkage, and is therefore more suitable for coating products by heat shrinkage.

[0052] In addition, in the thermoplastic fluorine-containing resin tube of the present invention, from the viewpoint of effectively suppressing the formation of gaps or bubbles at the joints of the tube when manufacturing the tube, in order to have tear resistance and eliminate the shrinkage characteristics of the raw tube in the longitudinal direction, the draw-down ratio (Draw-Down-Ratio, DDR) during the melt extrusion molding of the raw tube is preferably 40 or more, and more preferably about 40 to 100. Here, DDR is expressed by DDR=[(inner diameter of the extrusion die) 2 -(Core outer diameter) 2 ] / [(tube outer diameter) 2 -(tube inner diameter) 2 ] The larger the physical property values ​​calculated by DDR, the greater the molecular orientation in the length direction formed during the melt extrusion molding of the raw tube. However, by expanding the inner diameter of such a raw tube in the above-mentioned temperature range, the molecular orientation in the length direction can be easily alleviated.

[0053] The thermoplastic fluororesin tube of the present invention is thermally shrunk during the manufacture of the catheter, and is then torn and peeled off from the catheter. Therefore, in the thermoplastic fluororesin tube of the present invention, the one that requires particularly excellent tearing properties is the thermoplastic fluororesin tube of the present invention after the inner diameter of the thermoplastic fluororesin tube has been thermally shrunk. The tearing properties of the thermoplastic fluororesin tube whose inner diameter has been thermally shrunk after the inner diameter of the original tube has been expanded also depend on the size after shrinkage, but it is said to be a tearing property between the tearing properties of the thermoplastic fluororesin tube before the inner diameter is expanded (i.e., the original tube) and the tearing properties of the thermoplastic fluororesin tube before the inner diameter is expanded and thermally shrunk (i.e., the thermoplastic fluororesin tube of the present invention).

[0054] Regarding the tearing property of the thermoplastic fluorine-containing resin tube (i.e., the original tube) before the inner diameter is expanded, the tear strength measured by the following measurement method is preferably 12 N / mm or less, more preferably 10 N / mm or less, and further preferably 7 N / mm or less. In addition, as the lower limit of the tear strength of the original tube, 1 N / mm can generally be cited. In addition, regarding the tearing property of the thermoplastic fluorine-containing resin tube of the present invention, the tear strength measured by the following measurement method is preferably 16 N / mm or less, more preferably 14 N / mm or less, and further preferably 11 N / mm or less. Furthermore, regarding the tear strength of the thermoplastic fluororesin tube of the present invention after the inner diameter of the thermoplastic fluororesin tube is heat-shrunk, as described above, the tear strength is the difference between the tear strength of the thermoplastic fluororesin tube before the inner diameter is expanded (i.e., the original tube) and the tear strength of the thermoplastic fluororesin tube before the inner diameter is expanded and heat-shrunk (i.e., the thermoplastic fluororesin tube of the present invention). For example, the tear strength measured by the following measurement method is preferably 14 N / mm or less, more preferably 12 N / mm or less, and further preferably 9 N / mm or less.

[0055] (Determination of tear strength)

[0056] A 40 mm cut was made at one end of a thermoplastic fluorine resin tube (length 100 mm), and the tube was torn at a speed of 200 mm / min using a tensile tester. The maximum force at this time was measured and used as the tear strength (N). The measurement was performed three times, and the tear resistance (N / mm) of the thermoplastic fluorine resin tube was calculated based on the weighted average value and the two-wall thickness of the thermoplastic fluorine resin tube (2t = outer diameter - inner diameter).

[0057] The expansion ratio of the inner diameter of the raw tube may be, for example, 20% or more, preferably about 20 to 200%.

[0058] The inner diameter Wa and outer diameter Wb (respectively before the inner diameter is expanded) of the original tube of the thermoplastic fluorine-containing resin tube of the present invention are not particularly limited and can be appropriately set according to the product to be covered. The inner diameter Wa is, for example, about 0.2 to 10 mm, preferably about 0.2 to 5 mm. The outer diameter Wb is, for example, about 0.3 to 11 mm, preferably about 0.3 to 6 mm.

[0059] When the thermoplastic fluororesin tube of the present invention is used after heat shrinking, the inner diameter Wa of the thermoplastic fluororesin tube of the present invention before covering the catheter (i.e., after the inner diameter is expanded and before heat shrinking) can be, for example, about 0.3 to 20 mm, preferably about 0.3 to 10 mm; the outer diameter Wb can be, for example, about 0.5 to 25 mm, preferably about 0.5 to 12 mm. In addition, the inner diameter Wa of the thermoplastic fluororesin tube in the state of covering the catheter (i.e., after the inner diameter is expanded and further heat shrunk) can be, for example, about 0.2 to 10 mm, preferably about 0.2 to 5 mm; the outer diameter Wb can be, for example, about 0.3 to 11 mm, preferably about 0.3 to 6 mm.

[0060] In addition, the wall thickness D of the original tube (before the inner diameter is expanded) is not particularly limited and can be appropriately set according to the type of catheter. The wall thickness D can be, for example, about 0.03 to 1 mm, preferably about 0.05 to 0.5 mm, and particularly preferably about 0.15 to 0.5 mm. The length of the original tube (before the inner diameter is expanded) can also be appropriately set according to the product to be covered, for example, it can be 0.1 m or more, preferably about 0.1 to 2.5 m.

[0061] The wall thickness D of the thermoplastic fluorine-containing resin tube of the present invention (after the inner diameter is expanded and before the tube is heat-shrunk) is, for example, about 0.02 to 0.7 mm, preferably about 0.02 to 0.5 mm, and particularly preferably about 0.05 to 0.5 mm. In addition, the wall thickness D in the state of covering the catheter (i.e., after the inner diameter of the thermoplastic fluorine-containing resin tube of the present invention is heat-shrunk) is, for example, about 0.03 to 1 mm, preferably about 0.05 to 0.5 mm, and particularly preferably about 0.15 to 0.5 mm.

[0062] The thermoplastic fluorine-containing resin tube of the present invention preferably has a weld mark in the longitudinal direction. Thus, particularly excellent tearing properties can be exhibited. In the thermoplastic fluorine-containing resin tube of the present invention, the weld mark may be a weld mark that can be visually confirmed or a weld mark that cannot be visually confirmed. In the thermoplastic fluorine-containing resin tube of the present invention, the weld mark cannot usually be visually confirmed.

[0063] When weld lines are formed in the longitudinal direction of the thermoplastic fluororesin tube of the present invention, the number of the weld lines is not particularly limited, but is preferably about 1 to 10, more preferably about 2 to 8, from the viewpoint of further improving the tearing property.

[0064] When the thermoplastic fluororesin tube of the present invention has a weld mark in the longitudinal direction, it is possible to produce a thermoplastic fluororesin tube that is not only particularly excellent in tearing resistance, but also has a thermal expansion coefficient of 0% or more in the longitudinal direction and excellent in thermal shrinkage of the inner diameter. That is, in the thermoplastic fluororesin tube of the present invention having a weld mark in the longitudinal direction, even when the inner diameter is expanded by applying pressure from the inside of the original tube in a heated state, cracks are not likely to occur in the portion where the weld mark is formed, and the inner diameter of the original tube can be appropriately expanded. In addition, by heating the thermoplastic fluororesin tube of the present invention after the inner diameter is expanded, the thermal expansion coefficient in the longitudinal direction can be made to be 0% or more, and the inner diameter can be appropriately thermally shrunk. As a specific method for forming a weld mark on the thermoplastic fluororesin tube of the present invention, for example, the method described in "2. Method for manufacturing thermoplastic fluororesin tube" described later can be adopted.

[0065] The fluorine-containing tube made of fluorine-containing resin of the present invention is suitable for manufacturing catheters. In addition, it is also suitable for coating (pre-coating) various products such as electric wires, lead wires, catheters, and wires. By coating with the fluorine-containing tube made of fluorine-containing resin (pre-coated tube) of the present invention, various products such as electric wires, lead wires, catheters, and wires with appropriately protected surfaces can be obtained.

[0066] The method for producing the thermoplastic fluorine-containing resin tube of the present invention is not particularly limited, and the tube can be suitably produced by, for example, the following production method.

[0067] 2. Method for manufacturing thermoplastic fluorine-containing resin tube

[0068] The method for producing a thermoplastic fluororesin tube of the present invention comprises the steps of melt-extruding a thermoplastic fluororesin to obtain a raw tube of the thermoplastic fluororesin tube; and heating the raw tube to expand the inner diameter of the raw tube while the temperature of the raw tube is below 140°C.

[0069] In the production method of the present invention, the thermoplastic fluorine-containing resin to be subjected to melt extrusion molding is as described in the above-mentioned section "1. Tube made of thermoplastic fluorine-containing resin".

[0070] In melt extrusion molding, the temperature for melting the thermoplastic fluororesin (set temperature of the die of the extrusion molding machine) is not particularly limited as long as it is a temperature at which the thermoplastic fluororesin can be melted and molded into a tube, and for example, it can be about 260 to 450° C., preferably about 280 to 420° C. In addition, by mixing a filler or the like with the thermoplastic fluororesin for melt extrusion molding, as described in the above-mentioned "1. Thermoplastic fluororesin tube", the thermoplastic fluororesin tube can contain a filler or the like.

[0071] For melt extrusion molding, a known extrusion molding machine can be used, for example, a single-screw extruder can be used.

[0072] In the method for producing a thermoplastic fluororesin tube of the present invention, it is preferred that the flow path of the molten thermoplastic fluororesin is temporarily branched during melt extrusion molding, thereby forming a weld mark in the longitudinal direction of the original tube and then in the expanded thermoplastic fluororesin tube. In this way, a thermoplastic fluororesin tube having excellent tear resistance and heat shrinkage can be obtained. More specifically, in the method for producing the present invention, during melt extrusion molding, for example, a Figure 2 The mold 1 has a cross section (a cross section in a direction perpendicular to the direction in which the molten resin flows) shown in FIG. The shape of the mold 1 temporarily branches the flow path of the molten thermoplastic fluororesin, thereby forming a weld line in the longitudinal direction of the raw tube and further in the thermoplastic fluororesin tube of the present invention after the raw tube is expanded. For example, when using a mold having Figure 2 In the case of the mold 1 of the cross section shown in the figure, the plurality of legs 3 provided on the flow path 2 temporarily branches the flow path of the molten thermoplastic fluorine-containing resin. The branched thermoplastic resin protrudes from the mold with a weld mark formed at the confluent portion, and is cooled to form a thermoplastic fluorine-containing resin tube. Therefore, when forming weld marks using a mold having a structure in which the flow path 2 is branched by the legs 3, for example, as in the mold 1, the number of weld marks corresponding to the number of the legs 3 is formed. Figure 2 In the mold 1, eight legs 3 are provided.

[0073] Such a weld mark can effectively improve the tearing property of the thermoplastic fluorine-containing resin tube in the longitudinal direction.

[0074] In the manufacturing method of the present invention, the raw tube is heated and the inner diameter of the raw tube is expanded while the temperature of the raw tube is lower than 140°C, thereby obtaining the thermoplastic fluorine-containing resin tube of the present invention. As described above, in the prior art, the temperature for expanding the inner diameter of the raw tube is generally about 150 to 160°C, but in the present invention, when the inner diameter of the thermoplastic fluorine-containing resin tube is thermally contracted, the temperature of the raw tube when expanding the raw tube is set to be lower than 140°C so that the coefficient of thermal expansion in the longitudinal direction at a temperature of 100°C is 0% or more, and further exceeds 0%. The temperature (surface temperature) of the raw tube when expanding the raw tube is preferably about 100 to 135°C, more preferably about 100 to 130°C, further preferably about 100 to 125°C, and particularly preferably about 110 to 120°C.

[0075] As described above, in the thermoplastic fluorine-containing resin tube of the present invention, from the viewpoint of making the coefficient of thermal expansion in the longitudinal direction at a temperature of 100° C. 0% or more, and further exceeding 0% when manufacturing the tube, and effectively suppressing the formation of gaps or bubbles in the joint portion of the tube, the draw-down ratio (DDR) during the melt extrusion molding of the raw tube is preferably 40 or more, and more preferably about 40 to 100.

[0076] As described above, the expansion ratio of the inner diameter of the raw tube is preferably, for example, 20% or more, and preferably about 20 to 200%.

[0077] Example

[0078] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0079] (Example 1)

[0080] As a thermoplastic fluorine-containing resin, tetrafluoroethylene-hexafluoropropylene thermoplastic fluorine-containing resin copolymer (FEP, FEP-130J produced by DuPont-Mitsui Fluorochemicals Co., Ltd.) was used to manufacture a thermoplastic fluorine-containing resin tube by melt extrusion molding. In the melt extrusion molding, a single screw extruder with a barrel diameter of 30 mm assembled with a mold was used, and the tube was molded by a sizing plate method at a screw speed of 1 rpm and a mold temperature of 330°C to produce a thermoplastic fluorine-containing resin tube (original tube, before expansion) with an inner diameter of 0.25 mm, an outer diameter of 0.85 mm, and a wall thickness of 0.30 mm. As a mold, a mold with a width of 5 mm for the foot provided in the flow path of the molten resin, a length of 10 mm for the foot (the length of the branched flow path), 8 feet, and a distance of 10 mm from the die outlet side of the foot to the die outlet was used. In addition, the DDR during molding was set to 90. Next, the obtained raw tube was inserted into a barrel with an inner diameter of 1.4 mm, hot air was blown onto the surface of the raw tube, and while heating the raw tube to a temperature (surface temperature) of 110° C., pressurized nitrogen was added while the inner diameter was expanded, thereby producing a thermoplastic fluorine-containing resin tube (after expansion) with an inner diameter of 0.92 mm, an outer diameter of 1.32 mm, and a wall thickness of 0.2 mm.

[0081] (Example 2)

[0082] A thermoplastic fluorine-containing resin tube was produced in the same manner as in Example 1 except that the DDR during molding of the raw tube was set to 42 and the inner diameter was expanded while supplying pressurized nitrogen gas while heating the raw tube to a temperature of 120°C.

[0083] (Example 3)

[0084] Except that the DDR during the molding of the raw tube was set to 42, the same operation as in Example 1 was carried out to produce a thermoplastic fluorine-containing resin tube.

[0085] (Example 4)

[0086] A thermoplastic fluorine-containing resin tube was produced in the same manner as in Example 1 except that the inner diameter was expanded while the raw tube was heated to a temperature of 120°C and pressurized nitrogen was supplied.

[0087] (Example 5)

[0088] A thermoplastic fluorine-containing resin tube was produced in the same manner as in Example 1 except that the DDR during molding of the raw tube was set to 42 and the inner diameter was expanded while supplying pressurized nitrogen gas while heating the raw tube to a temperature of 135°C.

[0089] (Example 6)

[0090] As the thermoplastic fluorine-containing resin, a mixture of 98 parts by mass of tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEP, FEP-130J produced by Du Pont-Mitsui Fluorochemicals Co., Ltd.) and 2 parts by mass of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, PFA950HPplus produced by Du Pont-Mitsui Fluorochemicals Co., Ltd.) was used, and a thermoplastic fluorine-containing resin tube was manufactured in the same manner as in Example 1, except that the inner diameter was expanded while heating the original tube to a temperature of 120°C and adding pressurized nitrogen.

[0091] (Comparative Example 1)

[0092] A thermoplastic fluorine-containing resin tube was produced in the same manner as in Example 1 except that the inner diameter was expanded while the raw tube was heated to a temperature of 150°C and pressurized nitrogen was supplied.

[0093] (Comparative Example 2)

[0094] A thermoplastic fluorine-containing resin tube was produced in the same manner as in Comparative Example 1 except that the DDR during molding of the raw tube was set to 42.

[0095] (Comparative Example 3)

[0096] A thermoplastic fluorine-containing resin tube was manufactured in the same manner as in Comparative Example 1, except that a mixture of 90 parts by mass of a tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEP, FEP-130J produced by Du Pont-Mitsui Fluorochemicals Co., Ltd.) and 10 parts by mass of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, PFA950HPplus produced by Du Pont-Mitsui Fluorochemicals Co., Ltd.) was used as the thermoplastic fluorine-containing resin.

[0097] (Thermal expansion coefficient in the longitudinal direction after heating at 100°C)

[0098] Each thermoplastic fluorine-containing resin tube obtained above (after expansion) was heated in an oven heated to 100°C (under air) for 5 minutes. Next, the length of each thermoplastic fluorine-containing resin tube before and after heating was measured, and the thermal expansion coefficient in the longitudinal direction was calculated by the following formula. The results are shown in Table 1. However, in the case where the length of each thermoplastic fluorine-containing resin tube before and after heating was shrunk, the value of the thermal expansion coefficient in the longitudinal direction was recorded as a negative value.

[0099] Thermal expansion coefficient in the longitudinal direction (%) = [(length of the thermoplastic fluororesin tube after heating) - (length of the thermoplastic fluororesin tube before heating)] / (length of the thermoplastic fluororesin tube before heating) × 100

[0100] (Thermal shrinkage of inner diameter after heating at 200°C)

[0101] Each thermoplastic fluorine-containing resin tube obtained above (after expansion) was heated in an oven heated to 200° C. (under air) for 5 minutes. Then, the inner diameter before and after heating was measured with a pin gauge, and the shrinkage ratio was calculated from the following formula. The results are shown in Table 1.

[0102] Thermal shrinkage ratio of inner diameter (%) = [(inner diameter of thermoplastic fluorine-containing resin tube before shrinkage (after expansion)) - (inner diameter of thermoplastic fluorine-containing resin tube after shrinkage (after expansion and shrinkage))] / (inner diameter of thermoplastic fluorine-containing resin tube before shrinkage (after expansion)) × 100 (Evaluation of tearing properties)

[0103] Each thermoplastic fluorine-containing resin tube (after expansion) obtained above was cut into a length of 100 mm to prepare an expanded tube. In addition, the shrunk thermoplastic fluorine-containing resin tube (after expansion and contraction) obtained in the above (heat shrinkage rate of the inner diameter after heating at 200°C) was cut into a length of 100 mm to prepare an expanded / contracted tube. Next, a 40 mm incision was set at one end of the expanded tube and the expanded / contracted tube, respectively, and the tube was torn at a speed of 200 mm / min using a tensile testing machine. The maximum force at this time was measured as the tear strength (N). The measurement was performed three times, and the tear resistance (N / mm) of the expanded tube and the expanded / contracted tube was calculated based on the weighted average value and the wall thickness of the expanded tube and the expanded / contracted tube. The results are shown in Table 1.

[0104] (Evaluation of transparency)

[0105] A white nylon thread was inserted into the inside of each thermoplastic fluorine-containing resin tube (before expansion), and each thermoplastic fluorine-containing resin tube was observed from the outside and evaluated according to the following evaluation criteria.

[0106] A: The white nylon thread on the inside is clearly visible and has a very high transparency.

[0107] B: The white nylon thread inside is visible through, with high transparency

[0108] C: The white nylon thread on the inside cannot be seen through, and the transparency is low

[0109] (Volatile components are generated after heating at 400°C)

[0110] Each of the thermoplastic fluorine-containing resin tubes obtained above (after expansion) was heated in an oven at 400°C for 1 hour, and the ratio of the generated volatile components was measured. As a result, the ratio of the volatile components in the thermoplastic fluorine-containing resin tubes of Examples 1 to 6 and Comparative Examples 1 to 3 was 0.2 mass % or less.

[0111] (Manufacture of catheters)

[0112] like Figure 1 As shown in the schematic diagram of FIG. , the above-obtained thermoplastic fluorine-containing resin tubes (after expansion) were used to manufacture catheters, and the effect of suppressing the formation of gaps or bubbles in the joints of the catheters during the manufacture of the catheters was confirmed. Specifically, a polytetrafluoroethylene (PTFE)-coated A SUS wire is used as a core mold, and two nylon elastomer tubes (Pebax (registered trademark) tubes produced by ARKEMA) (6333 and 7233) with different hardness and an inner diameter of 0.70 mm and an outer diameter of 0.90 mm with a length of about 30 mm are coated. At this time, the end faces of the two Pebax tubes are brought into contact and joined by melting. In addition, a thermoplastic fluorine-containing resin tube (after expansion) is coated on the two Pebax tubes, and then moved in the direction of the heating part at a speed of 5 mm / s, and passed through a movable warm air heater (set temperature 200°C) as a heating part to shrink the thermoplastic fluorine-containing resin tube (after expansion), so as to produce a catheter formed by joining the two Pebax tubes. For each thermoplastic fluorine-containing resin tube (after expansion), 10 tests (N=10) were carried out, and the number of defects (gap or bubble generation) at the joint of the two Pebax tubes with different hardness in the obtained catheter was measured. The effect of suppressing the formation of gaps or bubbles at the joint portion of the catheter during the production of the catheter was evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0113] A: The number of times the bad condition occurs is 0 times.

[0114] B: The bad condition occurs 1 to 2 times.

[0115] C: The number of occurrences of the adverse condition is 3 to 10 times.

[0116] [Table 1]

[0117]

[0118] Explanation of symbols

[0119] 1: mold; 2: flow path; 3: leg; 10: heat shrinkable tube; 20: core; 30: thermoplastic resin tube; 31: thermoplastic resin tube; 40: heating part; P: joint part.

Claims

1. Use of a thermoplastic fluorine-containing resin tube for manufacturing a catheter, characterized in that: The thermoplastic fluorine-containing resin tube has tearability in the longitudinal direction. The coefficient of thermal expansion in the longitudinal direction after heating in a gas phase at a temperature of 100°C for 5 minutes is 0% or more. The thermoplastic fluorine-containing resin tube is made by the following manufacturing method, which comprises: A step of obtaining a raw tube of a thermoplastic fluorine-containing resin tube by melt extrusion molding the thermoplastic fluorine-containing resin; and The step of heating the shell tube to expand the inner diameter of the shell tube while keeping the shell tube temperature at 110 to 135°C.

2. The use according to claim 1, characterized in that The thermoplastic fluorine-containing resin tube has a heat shrinkage rate of the inner diameter of 40% or more when heated in a gas phase at a temperature of 200° C. for 5 minutes.

3. The use according to claim 1 or 2, characterized in that: The thermoplastic fluorine-containing resin is formed of at least one of a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

4. The use according to claim 1 or 2, characterized in that: The coefficient of thermal expansion of the thermoplastic fluorine-containing resin tube in the longitudinal direction when heated at 100° C. for 5 minutes is 0 to 4%.

5. The use according to claim 1 or 2, characterized in that: The thermoplastic fluorine-containing resin tube has a weld mark in the longitudinal direction.

Images