tube

Abstract

The present invention relates to a tube having one or more layers made of polytetrafluoroethylene, and addresses the problem of providing a tube having controlled flexibility while maintaining high mechanical strength. The problem can be suitably solved by a tube having one or more layers formed by winding a PTFE film in a helical shape. The tube has an endothermic peak in the range of 380°C ± 10°C when heated during DSC measurement. In one or more of the layers, the number of turns per 10 mm length in the longitudinal direction is not uniform.

Description

[Technical Field]

[0001] The present invention relates to a tube using polytetrafluoroethylene (hereinafter referred to as "PTFE"). [Background technology]

[0002] There are products in which a fluororesin lining is provided on the inner layer of a tubular body, such as for medical applications or fluid transport pipes that require chemical resistance. PTFE is a suitable lining material, particularly when the tubular body is used for applications that require chemical resistance, cleanliness, non-stickiness, low friction, etc. For example, a catheter with a PTFE liner tube as the innermost layer is known to improve the lubricity of the inner surface.

[0003] Catheters used in intravascular surgery and other procedures must be inserted percutaneously into the body and passed through blood vessels to reach the lesion, requiring them to have the ability to move straight through the blood vessel, the ability to transmit the surgeon's commands, and flexibility to reduce the burden on the patient. To meet all of these requirements, catheters are constructed by laminating layers with different properties, and the innermost layer, the PTFE liner tube, is required to be thin-walled yet have excellent mechanical strength, including high tensile strength, elongation, crack resistance, pressure resistance, and buckling resistance.

[0004] One method for manufacturing a PTFE liner tube involves dip-coating a core wire, such as a metal wire, with a PTFE dispersion, drying and sintering the core wire, and then drawing out and shaping the tube (see, for example, Patent Document 1). Another method involves extruding a paste made by mixing PTFE powder with an organic solvent known as an auxiliary onto a core wire, drying and sintering the paste, and then drawing out and shaping the tube (see, for example, Patent Document 2). The PTFE liner tubes formed by the methods of Patent Document 1 and Patent Document 2 have low mechanical strength, and when such a liner tube is used as the innermost layer of a catheter, friction between the inner surface of the catheter and the inserted object (such as a medical device) can cause problems such as damage to the PTFE liner, such as tearing or rupture, or the liner tube stretching, reducing its inner diameter and causing the inserted object to become caught.

[0005] Another method for producing PTFE liner tubes involves extruding a paste containing PTFE powder and an auxiliary agent into a tubular shape, and then stretching the resulting liner tube longitudinally to thin the wall and improve the tensile strength of the tube (see Patent Document 3). PTFE liner tubes formed by this method have high tensile strength, but suffer from poor extensibility and poor flexibility. A tube with poor flexibility requires a strong operating force when reducing the bending radius, and its hardness makes it prone to buckling, leading to problems such as tube blockage due to buckling or the insertion of inserted objects. Patent Document 4 discloses a thin-walled PTFE tube with high tensile strength and extensibility, but the flexibility of the tube is insufficient for applications requiring higher performance.

[0006] Furthermore, some catheters have a tapered shape to improve the flexibility of the tip of the catheter. The PTFE liner tube used in tapered catheters is stretched and reduced in diameter over a tapered core wire to cover it. By tapering the tube, the flexibility of the shaped part is improved, but the stretching of the PTFE tube reduces its flexibility, and the expected effect is not fully achieved. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-316977 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-176583 [Patent Document 3] JP 2004-340364 A [Patent Document 4] Patent No. 6244490 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above-mentioned problems, an object of the present invention is to provide a thin-walled tube using PTFE that has adjusted flexibility while maintaining high tensile strength. [Means for solving the problem]

[0009] This problem involves the development of a membrane having at least one layer formed by spirally winding a PTFE film. A tube having an endothermic peak in the range of 380°C ± 10°C during the temperature rise process of DSC of the tube, The aforementioned The number of turns per 10 mm in the longitudinal direction is not uniform in at least one layer. Contains parts This can be solved by using tubes.

[0010] Furthermore, when the layer formed by spirally winding the PTFE film consists of two or more layers, it is preferable that at least one or more layers are spirally wound clockwise and at least one or more layers are spirally wound counterclockwise.

[0011] The layer more preferably has an average thickness of 3 μm or more and 75 μm or less.

[0012] The tube has a tensile strength of 100 N / mm2, as determined by a tensile test in accordance with JIS K7127-1999. 2 It is preferable that this is equal to or greater than this.

[0013] The object of the present invention can be achieved by providing a tube having at least one layer formed by spirally winding a PTFE film, wherein the tube has an endothermic peak in the range of 380°C ± 10°C during the temperature rise process in a DSC of the tube, and wherein the maximum and minimum number of turns per 10 mm length in the longitudinal direction in at least one of the layers differ by at least 0.1 turns / 10 mm. [Effects of the Invention]

[0014] By adopting the above-described configuration, it is possible to adjust the flexibility in the longitudinal direction of the tube while maintaining high tensile strength throughout the tube, resulting in a tube with excellent flexibility. The tube of the present invention can be configured with a thin wall, and is suitable as a liner tube for a tubular body that requires flexibility and a small diameter. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a conventional tube. [Figure 2] FIG. 2 is a diagram showing an example of the tube of the present invention. [Figure 3] FIG. 3 is a schematic diagram illustrating the structure of the PTFE layer of the tube of the present invention. [Figure 4] FIG. 4 is a diagram illustrating the wound structure of the PTFE film of the tube of the present invention. [Figure 5] FIG. 5 is a diagram illustrating parameters related to the tube of the present invention. [Figure 6] FIG. 6 is a diagram illustrating how to count the number of wraps of the film in the tube of the present invention. [Figure 7] FIG. 7 is a diagram illustrating the number of wraps of the film in the tube of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] FIG. 1 is a diagram showing a conventional tube made by spirally winding a film. Conventional tubes are formed by winding a film with a constant number of turns over the entire length of the tube. The tube of the present invention preferably includes a portion in which the number of turns of the film is not constant in the longitudinal direction. A tube according to a preferred embodiment of the present invention will now be described. FIG. 2 is a diagram illustrating an example of a tube of the present invention. The tubes in FIGS. 2a and 2b have at least one layer formed by spirally winding a PTFE film. In the example of FIG. 2, at least the outermost layer of the tube is formed by spirally winding a PTFE film, with the number of film windings on the left side being greater than the number of film windings on the right side. This results in a tube with improved flexibility on the left side while maintaining the tensile strength of the entire tube. In addition to this layer, the tube of the present invention may also have a layer formed by spirally winding a PTFE film, a layer formed from a seamless PTFE film, a layer formed by cigarette-wrapping a PTFE film, or a layer formed from a resin other than PTFE. Furthermore, while FIG. 2 illustrates an example of a tube with a smaller outer diameter on the left side than on the right side, the present invention is not limited to this and the outer diameter may be constant.

[0017] FIG. 3 is a schematic diagram illustrating the structure of a tube having at least one layer formed by spirally winding the PTFE film of the present invention. In the example of FIG. 3a, film 111a is spirally wound around the outer periphery of core wire 2 as a first layer, and film 121a is spirally wound around the outer periphery with a gap therebetween as a second layer. In the example of FIG. 3b, cylindrical PTFE film 111b is disposed around the outer periphery of core wire 2 as a first layer, and film 121b is spirally wound around the outer periphery as a second layer. In the example of FIG. 3, the layer formed by spirally winding the PTFE film consists of one or two layers, but the tube of the present invention may consist of three or more layers. Furthermore, the tube of the present invention may have a layer of PTFE or a resin other than PTFE laminated on the inner or outer side of the layer formed by spirally winding the PTFE film.

[0018] The layers formed by spirally winding the PTFE film of the tube of the present invention preferably have a thin average thickness. The average thickness of the entire layer formed by spirally winding the PTFE film of the tube of the present invention is preferably 100 μm or less, and the average thickness of one layer formed by spirally winding the PTFE film is preferably 3 μm or more and 75 μm or less. The average thickness of one layer is more preferably 5 μm or more and 50 μm or less, and even more preferably 5 μm or more and 40 μm or less.

[0019] FIG. 4 is a diagram illustrating the structure of layers formed by spirally winding a PTFE film of the tube of the present invention. In the present invention, "having one or more layers formed by spirally winding a PTFE film" means having one or more layers formed by spirally winding a single PTFE film. In the present invention, "one film" also includes a structure in which multiple films are stacked and wound at the same angle. For example, in the example of FIG. 4, a first layer 210 is formed by spirally winding a PTFE film 211 around the outer periphery of the core wire 2. Outside of that, a second layer 220 is formed by spirally winding a PTFE film 221. The PTFE film 211 is composed of a laminate of one PTFE film 211a and one thermoplastic fluororesin film 211b. The PTFE film 221 of the second layer 220 is composed of one PTFE film 221a.

[0020] When the tube of the present invention has two or more layers formed by spirally winding a film, it is more preferable that at least one layer is wound clockwise and at least one layer is wound counterclockwise. In the example of Figure 4, there are two layers formed by spirally winding a film. The film 211 of the first layer 210 is wound counterclockwise (S-winding), and the film 221 of the second layer 220 is wound clockwise (Z-winding). This structure makes it easier to adjust the mechanical strength of the tube.

[0021] In the tube of the present invention, it is preferable that the number of windings per 10 mm in the longitudinal direction is not constant in at least one of the layers formed by spirally winding the PTFE film. The number of windings per 10 mm in the longitudinal direction of a single tube can be varied, for example, by varying the speed at which the film is wound around the core wire while feeding the core wire at a constant speed during the process of winding the film around the core wire. In this case, using a tapered core wire makes it easier to adjust the number of windings of the film.

[0022] The PTFE film used in the tube of the present invention is preferably made of high-density PTFE. The inclusion of high-density PTFE is advantageous for achieving high airtightness and mechanical strength. A film made of high-density PTFE can be produced, for example, as follows: PTFE resin fine powder is mixed with an auxiliary agent (a lubricant such as solvent naphtha or white oil), compressed, and the resulting preform is placed in an extruder to be molded into a film, which is then dried. Upon drying, the auxiliary agent in the molded film volatilizes, resulting in an unsintered PTFE film with pores. Sintering the unsintered PTFE film by heating it to a temperature above its melting point eliminates the pores, resulting in a high-density PTFE film. At this time, the film can also be further compressed through a pressure roll. Alternatively, the unsintered PTFE film can be stretched uniaxially or biaxially while heated below its melting point to produce a porous PTFE film, which can then be pressurized to produce a high-density PTFE film. The PTFE film used in the tube of the present invention is preferably a PTFE film that has been stretched to form a porous structure and then compressed to densify it. The compressed and densified film may be baked before use. The film is generally slit to an appropriate width before use. Alternatively, the porous PTFE film described above can be spirally wound around the outer periphery of a core wire, and then passed through a ring-shaped die to apply pressure, thereby converting the porous structure into high-density PTFE.

[0023] The PTFE film used in the tube of the present invention may contain a filler or other resin as needed. Examples of fillers include metal oxides such as carbon and alumina, and resin fillers. Examples of other resins include thermoplastic fluororesins. These can be used alone or in combination.

[0024] The PTFE film used in the tube of the present invention may be constructed by laminating a PTFE film and a thermoplastic fluororesin film as described above. The fluororesin used as the material for the thermoplastic fluororesin film is preferably a resin with a melting point lower than the crystalline melting point of PTFE, such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). When a PTFE film is formed by laminating a PTFE film and a thermoplastic fluororesin film, the ratio of the thickness (total) of the films made of the respective resins is preferably in the range of (PTFE resin / thermoplastic fluororesin) = 10 / 1 to 1 / 1.

[0025] The PTFE film used in the tube of the present invention preferably has a thickness of 2 μm to 25 μm, more preferably 3 μm to 25 μm, and even more preferably 3 μm to 20 μm. The thinner the film, the smaller the step in the film winding when the film is wound spirally, which is advantageous for the properties of the tube, such as reducing the effect on the surface of the tube. However, if the film is too thin, the film may be prone to wrinkling or tearing when wound.

[0026] The width of the PTFE film used in the tube of the present invention can be determined depending on the inner diameter and thickness of the layer formed by spirally winding the PTFE film, the number of wraps of the PTFE film, and other factors. Figure 5 illustrates the parameters to consider when determining the width of the PTFE film used in the tube of the present invention. When the outer diameter of the core wire 2 around which the PTFE film is wound (the inner diameter of the layer formed by spirally winding the PTFE film) is D, the winding angle of the PTFE film 311 is α, the distance traveled by the PTFE film 311 when wound around the outer periphery of the core wire 2 is p, and the amount of overlap between the wound PTFE film 311 layers is b, the width W of the film 311 can be calculated using the following formula: Here, the winding angle α of the film is the angle between the central axis A of the core wire 2 and the center line B along the longitudinal direction of the PTFE film 311, and is greater than 0 degrees and less than 90 degrees. p=πD / tanα W=(p+b)sinα

[0027] The tube of the present invention preferably has an endothermic peak in the range of 380°C ± 10°C during the temperature rise process in differential scanning calorimetry (DSC). When DSC is performed on a molded PTFE product, two endothermic peaks, one on the low side and one on the high side, may be observed due to differences in the crystalline structure. In general, the high-temperature endothermic peak that appears near 380°C is believed to be an endothermic peak derived from extended chain crystals of PTFE. The PTFE film used in the tube of the present invention preferably includes a PTFE film that has been uniaxially or biaxially stretched to form a porous structure film as described above, and then compressed to form a high-density PTFE film. An endothermic peak in the range of 380°C ± 10°C can also be observed by stretching PTFE.

[0028] The layer of the tube of the present invention formed by spirally winding the PTFE film preferably has 0.3 to 10 turns / 10 mm, more preferably 0.5 to 8 turns / 10 mm, per 10 mm in the longitudinal direction of the tube. The number of turns of the film does not need to be the same for all layers formed by spirally winding the film, and each layer may be configured with a different number of turns.

[0029] Furthermore, in at least one layer formed by spirally winding the PTFE film, the maximum and minimum number of turns per 10 mm in the longitudinal direction of the tube preferably differ by at least 0.1 turns / 10 mm, more preferably by 0.5 turns / 10 mm or more, and even more preferably by 1.0 turns / 10 mm or more. In this case, the rate of change in the number of turns per 10 mm of the film in the longitudinal direction of the tube ((((maximum number of turns per 10 mm of the film) - (minimum number of turns per 10 mm of the film)) / (minimum number of turns per 10 mm of the film)) x 100) (%) is preferably in the range of 10% to 800%, more preferably in the range of 50% to 700%. Each layer may be configured so that the difference or rate of change between the maximum and minimum number of turns of the film is different, or the range or position in the longitudinal direction of the tube over which the number of turns is changed may be different for each layer. By varying the number of wraps of the film along the length of the tube, the flexibility of the tube can be adjusted along the length of the tube. Furthermore, the tube of the present invention maintains tensile strength throughout the entire tube. For example, in the embodiment shown in Figure 2, the right side of the tube has high tensile strength, while the left side of the tube maintains the same tensile strength while improving the flexibility of the tube.

[0030] The method for manufacturing the tube of the present invention will be described in more detail in the following examples, which are intended to illustrate the invention but are not intended to limit the scope of the invention. [Example]

[0031] Example 1 <Creating a tube> A core wire with an outer diameter of 1.0 mm was prepared. The outer diameter of the left end of the core wire was 0.5 mm, and it was confirmed that the outer diameter changed at an angle of 0.72 degrees from the 1.0 mm outer diameter portion toward the left end. A 7 μm thick PTFE film was prepared as the first layer of PTFE film. Furthermore, a laminate of a 6 μm thick PTFE film and an 8 μm thick PFA film was prepared as the second layer of PTFE film. The prepared core wire was fed out at a constant speed, and the first layer of PTFE film was spirally wound around the outer circumference of the portion with an outer diameter of 1.0 mm of the core wire so that the number of turns per 10 mm in the longitudinal direction was 0.85 turns / 10 mm. In the portion where the outer diameter of the core wire changes from the portion with an outer diameter of 1.0 mm to the left end, the winding speed of the PTFE film was changed, and the PTFE film was wound so that the number of turns per 10 mm in the longitudinal direction of the left end was 3.50 turns / 10 mm. The second layer was laminated on the core wire on which the first layer was formed. Specifically, in the portion where the outer diameter of the core wire is 1.0 mm, the second layer of PTFE film was spirally wound so that the number of turns per 10 mm in the longitudinal direction was 0.80 turns / 10 mm. Also, in the portion where the outer diameter of the core wire changes from the portion with an outer diameter of 1.0 mm to the left end, the winding speed of the PTFE film was changed, and the second layer of PTFE film was spirally wound so that the number of turns per 10 mm in the longitudinal direction of the left end was 3.25 turns / 10 mm. The core wire laminated with the first and second layers of PTFE film was passed through an oven heated to 380 °C for baking and then air-cooled. Thereafter, only the core wire was stretched to reduce the outer diameter, and the core wire was extracted from the laminated and baked PTFE film to form a tube. The number of turns per 10 mm in the longitudinal direction of the fabricated tube differed between the maximum and minimum values, with 2.65 / 10 mm for the first layer and 2.45 turns / 10 mm for the second layer. <Differential Scanning Calorimetry (DSC)> For the tube sample prepared above, DSC was performed using DSC3200SA manufactured by NETZSCH JAPAN. A 5 mg piece of the tube was cut out, sealed in an aluminum sample pan with a cover, and heated from room temperature to 400 °C at a heating rate of 10 °C / min for measurement. From the DSC curve of the tube prepared in Example 1, it was confirmed that an endothermic peak appeared at 378.3 °C. <Number of turns of PTFE film> FIG. 6 is a diagram illustrating how to count the number of turns of the PTFE film for the tube of the present invention. FIG. 6 is a schematic diagram of a layer formed by spirally winding the PTFE film, viewed from the side. "Number of turns per 10 mm in the longitudinal direction" indicates how many times the PTFE film is wound in a 10 mm section on the central axis A of the tube. In FIG. 6, when counting the number of turns at position X, the number of turns is counted in a range of approximately 10 mm centered on X on the central axis A of the tube. Since it is easy to count using the wraps of the tape, for example, the number of turns between the nearest wraps y1 and y2 beyond the 10 mm range (between x1 and x2) is counted and converted to the number of turns per 10 mm. The number of turns between y1 and y2 is 5, and the distance between y1 and y2 is 12 mm. In this case, the number of turns per 10 mm in the longitudinal direction is (5 times / 12 mm) x 10 mm = 4.17 times / 10 mm This becomes: Figure 7a shows the first layer of the tube of Example 1 at the portion where the core wire has an outer diameter of 1.0 mm. Using the calculations described above, the number of turns per 10 mm of length in the longitudinal direction of the PTFE film is 0.85 turns / 10 mm. Figure 7b shows the first layer of the left end of the tube of Example 1. Using the calculations described above, the number of turns per 10 mm of length in the longitudinal direction of the PTFE film is 3.50 turns / 10 mm. The tube produced in Example 1 has different numbers of turns of the PTFE film between the portion where the core wire has an outer diameter of 1.0 mm and the left end, improving the flexibility of the left end of the tube. <Tensile test> Using a Shimadzu Autograph AGS-1kNX, tensile tests were carried out in accordance with JIS K7127-1999 in an environment of 23°C ± 2°C. The tubes were used as samples for the tensile tests, with a test speed of 50 mm / min and a chuck distance of 20 mm, with the chuck distance being the distance between the sample gauge lines (i.e., a gauge distance of 20 mm). For the tube prepared in Example 1, a region 35 mm from the left end of the tube was used as a sample for the tensile test of the left end of the tube, and a region 35 mm from the right end of the tube was used as a sample for the tensile test of the right end of the tube. For both samples, the number of turns per 10 mm in the longitudinal direction near the center between the sample gauge lines was confirmed using the method described above, and then tensile tests were conducted. The tube outer diameter and wall thickness near the center between the sample gauge lines were measured to determine the tube cross-sectional area, which was used as the cross-sectional area of ​​the tensile test sample. It is preferable to select samples for the tensile test so that they include the maximum and minimum number of turns within the entire tube. The tensile test was carried out by clamping both ends of the sample to the gauge line in the chucks of a tensile tester. The tensile strength of the right end of the tube in Example 1 was 247.6 N / mm 2 The tensile strength of the left end of the wire with the number of turns per 10 mm in the longitudinal direction was 331.1 N / mm 2 , and 100N / mm 2 It was confirmed that the tensile strength of the entire tube was maintained. The measured values ​​also confirmed the change in tensile stress when the strain of the tube was changed from 2.5% to 5.0%. The stress σ at the left end of the tube when the strain was 2.5% was 2.5 is 42.8N / mm 2 , stress σ at strain 5.0% 5.0 is 69.8N / mm 2 The rate of change of tensile stress E is E = stress change / displacement = (σ 5.0 -σ 2.5 / 0.025) = 27.0 / 0.025 = 1080N / mm 2 The stress σ at the strain of 2.5% of the tensile test sample at the right end of the tube in Example 1 was 2.5 is 39.7N / mm 2 , stress σ at strain 5.0% 5.0 is 89.4N / mm 2 The rate of change of tensile stress E is E = stress change / displacement = (σ 5.0 -σ 2.5 / 0.025) = 49.7 / 0.025 = 1988N / mm 2 This rate of change in tensile stress serves as an index for relatively evaluating the tensile modulus of a tube. It was confirmed that the tensile modulus of the tube in Example 1 changed by nearly two times in the longitudinal direction by changing the number of turns per 10 mm in the longitudinal direction.

[0032] Example 2 <Creating a tube> A core wire with an outer diameter of 1.0 mm was prepared. The outer diameter of the left end of the core wire was 0.75 mm, and it was confirmed that the outer diameter changed at an angle of 0.36 degrees from the 1.0 mm outer diameter portion toward the left end. A 7 μm thick PTFE resin film was prepared as the first layer of PTFE film. A 6 μm thick PTFE resin film was prepared as the second layer of PTFE film. The prepared core wire was fed out at a constant speed, and a first layer of PTFE film was spirally wound around the outer circumference of the 1.0 mm outer diameter portion of the core wire so that the number of turns per 10 mm in the longitudinal direction was 0.84 turns / 10 mm. In the portion where the outer diameter of the core wire changes from the 1.0 mm outer diameter portion to the left end, the speed at which the PTFE film was wound was changed so that the number of turns per 10 mm in the longitudinal direction of the left end was 1.95 turns / 10 mm. The second layer was laminated on top of the core wire on which the first layer had been formed. Specifically, in the portion of the core wire where the outer diameter was 1.0 mm, the second layer of PTFE film was spirally wound so that the number of turns per 10 mm in the longitudinal direction was 0.85 / 10 mm, and in the portion where the outer diameter of the core wire changes from the portion with an outer diameter of 1.0 mm to the left end, the speed at which the PTFE film was wound was changed so that the number of turns per 10 mm in the longitudinal direction at the left end was 1.88 / 10 mm. The core wire with the first and second PTFE film layers laminated was passed through an oven heated to 380°C to be baked, and then air-cooled. After that, only the core wire was stretched to reduce its outer diameter, and the core wire was removed from the baked PTFE film laminate to form a tube. The maximum and minimum number of turns per 10 mm in the longitudinal direction of the produced tube differed by 1.11 turns / 10 mm for the first layer and 1.03 turns / 10 mm for the second layer. DSC was performed on the prepared tube in the same manner as in Example 1. It was confirmed from the DSC curve that an endothermic peak appeared at 379.7°C. In addition, similarly to Example 1, the produced tube was subjected to a tensile test. The tensile strength of the right end of the tube in Example 2 was 248.4 N / mm 2 The tensile strength of the left end of the wire with the number of turns per 10 mm in the longitudinal direction was 343.2 N / mm 2 , and it was confirmed that the tensile strength of the entire tube was maintained. In addition, the stress σ at the left end of the tube at a strain of 2.5% 2.5 is 44.8N / mm 2 , stress σ at strain 5.0% 5.0 is 86.9N / mm 2 The rate of change of tensile stress E is E = stress change / displacement = (σ 5.0 -σ 2.5 / 0.025) = 42.1 / 0.025 = 1684N / mm 2 The stress σ at the strain of 2.5% of the tensile test sample at the right end of the tube in Example 1 was 2.5 is 50.5N / mm 2 , stress σ at strain 5.0% 5.0 is 100.4N / mm 2 The rate of change of tensile stress E is E = stress change / displacement = (σ 5.0 -σ 2.5 / 0.025) = 49.9 / 0.025 = 1996N / mm 2 It was confirmed that the tensile modulus of elasticity of the tube in Example 2 changed in the longitudinal direction of the tube. [Industrial Applicability]

[0033] The tube of the present invention is thin-walled and maintains high tensile strength throughout the tube, while allowing for adjustment of flexibility in the longitudinal direction of the tube, making it suitable for use as a liner tube for tubular objects that require flexibility and a small diameter. [Explanation of symbols]

[0034] 1 Tube of the present invention, 111a, 121a Film, 2 Core material

Claims

1. A tube having at least one layer formed by spirally winding a PTFE film. It is Bu, the tube has an endothermic peak in the range of 380°C ± 10°C during the temperature rise process of DSC, and the layer formed by spirally winding the PTFE film has an average thickness of 100 µm or less; A tube characterized in that at least one of the layers includes a portion in which the number of turns per 10 mm in the longitudinal direction of the tube is not constant.

2. 2. The tube of claim 1, wherein at least one of the layers is spirally wound in a right-handed manner and at least one of the layers is spirally wound in a left-handed manner.

3. A tube as described in claim 1 or 2, characterized in that the thickness of the PTFE film is 2 μm or more and 25 μm or less.

4. Tensile strength of 100N / 4. The tube according to claim 1, wherein the thickness of the tube is equal to or greater than mm2.

5. A tube described in any one of claims 1 to 4, characterized in that in at least one of the layers, the maximum and minimum number of turns per 10 mm of length in the longitudinal direction of the tube differ by at least 0.1 turns / 10 mm or more.

6. A tube described in any one of claims 1 to 4, characterized in that in at least one of the layers, the maximum and minimum number of turns per 10 mm of length in the longitudinal direction of the tube differ by at least 10% or more.

7. A tube as described in claim 5 or 6, characterized in that the longitudinal tensile modulus of elasticity of the part of the tube where the number of turns per 10 mm in the longitudinal direction is maximum is smaller than the longitudinal tensile modulus of elasticity of the part of the tube where the number of turns per 10 mm in the longitudinal direction is minimum.

8. 8. The tube according to claim 1, wherein the tube has one end and the other end, and further has a midpoint between the one end and the other end, and the number of turns per 10 mm in the longitudinal direction of the tube at the one end and the midpoint is equal, while the number of turns per 10 mm in the longitudinal direction of the tube at the other end is greater than those at the other end.

9. A tube as described in any one of claims 1 to 8, characterized in that the longitudinal tensile modulus of elasticity of the one end of the tube is greater than the longitudinal tensile modulus of elasticity of the other end.

10. A tube described in any one of claims 1 to 9, characterized in that the other end side of the tube is more flexible than the one end side.

11. A tube as described in any one of claims 1 to 10, characterized in that the outer diameter of the one end of the tube is larger than the outer diameter of the other end.

12. The tube of claim 11, wherein the outer diameters at the one end and the midpoint of the tube are equal, and the outer diameter at the other end is smaller than these.

13. A tube as described in claim 11 or 12, characterized in that the number of turns per 10 mm in the longitudinal direction of the tube at one end of the tube is smaller than the number of turns per 10 mm in the longitudinal direction of the tube at the other end of the tube.

14. A tube as described in any one of claims 1 to 13, characterized in that the flexibility of the tube changes depending on the range in which the number of turns per 10 mm of length in the longitudinal direction of the tube is changed.

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