Laminated tube

Abstract

The present invention provides a laminated tube comprising polytetrafluoroethylene as a main component, which is flexible and has excellent airtight durability. This can be achieved by a laminated tube comprising polytetrafluoroethylene as a main component, wherein the horizontal axis of the graph represents the total porosity (%) of the tube and the vertical axis represents the Martens hardness (HM) of the tube. 3mN When the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the graph. 3mN When the inner surface of a tube is measured in accordance with ISO 14577, the Martens hardness is expressed when the test force reaches 3 mN during the application of the load with a maximum test force of 4 mN.

Description

Technical Field

[0001] The present invention relates to a laminated tube mainly composed of polytetrafluoroethylene and having excellent airtightness durability and bending resistance. Background Art

[0002] In applications requiring chemical resistance, heat resistance, and the like, tubes made of porous polytetrafluoroethylene (hereinafter referred to as PTFE) are used as tubes with excellent flexibility. Known examples include tubes in which these porous tubes are made airtight (Prior Art Document 1) and tubes comprising layers composed of solid polytetrafluoroethylene and thermoplastic fluororesins (Prior Art Document 2). These flexible tubes have the following problems: since the majority of the tube is composed of porous PTFE, they can be bent with a small bending radius. However, repeated bending at a small bending radius places a heavy load on the inner layer composed of the solid PTFE film, causing cracks to form at an early stage and reducing airtightness.

[0003] Laminated tubes made of porous PTFE with an airtight inner layer are used in various applications to insert fluids, clamps, cables, etc. into the tubes. However, if the bending radius is too small, the bent portion of the tube becomes flat, making it difficult to use.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 6-270301

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 8-72178 Summary of the Invention

[0008] An object of the present invention is to provide a flexible laminated tube comprising polytetrafluoroethylene as a main component that is excellent in airtightness and durability. Another object of the present invention is to provide a flexible laminated tube that is excellent in bending resistance and can suppress flattening when the tube is bent.

[0009] The inventors of the present invention have conducted intensive research to solve the above-mentioned problems and have found that the following laminated tube is a preferred solution to the above-mentioned problems, thereby completing the present invention: a laminated tube containing polytetrafluoroethylene as a main component, wherein the horizontal axis of the graph represents the total porosity (%) of the tube and the vertical axis represents the Martens hardness HM of the tube. 3mN When , the coordinate point representing the characteristic enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure.

[0010] More preferably, the horizontal axis of the graph of the laminated tube is the total porosity (%) of the tube, and the vertical axis is the Martens hardness HM of the tube. 3mN When , the coordinate point representing the characteristic enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the graph.

[0011] Furthermore, the problem of the present invention is preferably solved by a laminated tube comprising polytetrafluoroethylene as a main component, wherein the horizontal axis of the graph represents the total porosity (%) of the tube and the vertical axis represents the Martens hardness HM′ of the tube. 3mN When , the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure.

[0012] More preferably, the horizontal axis of the graph of the laminated tube is the total porosity (%) of the tube, and the vertical axis is the Martens hardness HM′ of the tube. 3mN When , the coordinate point representing the characteristic enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the graph.

[0013] In addition, the laminated tube of the present invention is preferably a laminated tube comprising polytetrafluoroethylene as a main component, wherein the total porosity of the laminated tube is 8% or more and 27% or less, and the indentation depth and Martens hardness of the inner surface of the laminated tube measured in accordance with ISO 14577-1 satisfy the following formulas (1) and (2).

[0014] 0.02≤HM 3mN ≤0.38 Formula (1)

[0015] -0.0450 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0010 / μm Formula (2)

[0016] Among them, D 3mN (μm) and HM 3mN The values D represent the penetration depth of the indenter when the test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 4mN (μm) and HM 4mN They respectively represent the penetration depth of the indenter when the maximum test force reaches 4 mN and the Martens hardness of the laminated tube.

[0017] The inner surface of the multi-layer tube of the present invention more preferably satisfies the following formulas (3) and (4) in terms of the indentation depth and Martens hardness measured in accordance with ISO 14577-1.

[0018] 0.03≤HM 3mN ≤0.33 Formula (3)

[0019] -0.0400 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0013 / μm Formula (4)

[0020] The inner surface of the multi-layer tube of the present invention preferably has an indentation depth and a Martens hardness as measured in accordance with ISO 14577-1 that satisfy the following formulas (5) and (6).

[0021] 0.04≤HM 3mN ≤0.25 Formula (5)

[0022] -0.0300 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0015 / μm Formula (6)

[0023] In addition, the laminated tube of the present invention is preferably a laminated tube comprising polytetrafluoroethylene as a main component, wherein the total porosity of the laminated tube is greater than or equal to 8% and less than or equal to 27%, and the indentation depth and Martens hardness of the inner surface of the laminated tube measured in accordance with ISO 14577-1 satisfy the following formulas (7) and (8).

[0024] 0.02≤HM' 3mN ≤0.38 Formula (7)

[0025] -0.0700 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0020 / μm Formula (8)

[0026] Among them, D' 2.5mN (μm) and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN (μm) and HM' 3mN They respectively represent the penetration depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube.

[0027] The inner surface of the multi-layer tube of the present invention more preferably satisfies the following formulas (9) and (10) in terms of the indentation depth and Martens hardness measured in accordance with ISO 14577-1.

[0028] 0.03≤HM' 3mN ≤0.33 Formula (9)

[0029] -0.0650 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0027 / μm Formula (10)

[0030] The inner surface of the multi-layer tube of the present invention preferably has an indentation depth and a Martens hardness measured in accordance with ISO 14577-1 that satisfy the following formulas (11) and (12).

[0031] 0.04≤HM' 3mN ≤0.25 Formula (11)

[0032] -0.0600 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0055 / μm Formula (12)

[0033] In addition, it is preferred that the horizontal axis of the graph of the laminated tube of the present invention represents the total porosity (%) of the tube, and the vertical axis represents the Martens hardness HM of the tube. 3mN When , the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure, and further satisfies the above-mentioned formula (2), more preferably further satisfies the formula (4), and further preferably further satisfies the formula (6).

[0034] In addition, it is preferred that the horizontal axis of the graph of the laminated tube of the present invention represents the total porosity (%) of the tube, and the vertical axis represents the Martens hardness HM of the tube. 3mN When , the coordinate point representing the characteristic enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the figure, and further satisfies the above-mentioned formula (2), more preferably further satisfies formula (4), and further preferably further satisfies formula (6).

[0035] In addition, it is preferred that the horizontal axis of the graph of the laminated tube of the present invention represents the total porosity (%) of the tube, and the vertical axis represents the Martens hardness HM′ of the tube. 3mNWhen , the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure, and further satisfies the above-mentioned formula (8), more preferably further satisfies formula (10), and further preferably further satisfies formula (12).

[0036] In addition, it is preferred that the horizontal axis of the graph of the laminated tube of the present invention represents the total porosity (%) of the tube, and the vertical axis represents the Martens hardness HM′ of the tube. 3mN When , the coordinate point representing the characteristic enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the figure, and further satisfies the above-mentioned formula (8), more preferably further satisfies formula (10), and further preferably further satisfies formula (12).

[0037] The laminated tube of the present invention has excellent airtightness durability and can maintain airtightness or liquidtightness even after being bent repeatedly 50,000 times or more. In addition, when the tube is naturally bent, it can be used while suppressing flattening of the bent portion of the tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of an example of the laminated tube of the present invention.

[0039] Figure 2 This is a diagram showing an example of a graph of the total porosity and the Martens hardness HM of the multi-layer tube of the present invention.

[0040] Figure 3 This is a diagram showing an example of a graph of the total porosity and the Martens hardness HM of the multi-layer tube of the present invention. DETAILED DESCRIPTION

[0041] The laminated tube of the present invention is mainly composed of PTFE. In the present invention, "main component" means that it constitutes more than 90% by volume of all the resins constituting the tube. The PTFE used in the present invention can be a homopolymer of tetrafluoroethylene (hereinafter referred to as "TFE"), or it can be a modified PTFE. Modified PTFE is formed by polymerizing TFE with a small amount of monomers other than TFE. Examples of monomers other than TFE in a small amount include chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and perfluoroalkyl vinyl ether (PPVE). The laminated tube can also contain resins other than PTFE. Examples of resins other than PTFE constituting the laminated tube include tetrafluoroethylene / hexafluoroethylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene copolymer (PCTFE), and polyvinylidene fluoride (PVDF).

[0042] The multi-layer tube of the present invention has two or more layers. By having two or more layers, a multifunctional tube can be constructed. Figure 1 An example of the laminated tube of the present invention is schematically shown. Figure 1 The laminated tube 1 is a two-layer structure as a simple example. For example, a dense layer or an airtight layer may be provided on one of the two layers. A dense layer is a layer with excellent airtightness or liquidtightness, and a soft layer is a layer with high flexibility. In the present invention, other functional layers may also be provided.

[0043] The dense layer is preferably made of high-density PTFE, and the thickness of the dense layer is preferably 0.075mm to 0.20mm, more preferably below 0.15mm. In order to form the dense layer, there are methods of extruding PTFE into a tubular shape with high density, winding a high-density PTFE film into a cylindrical shape, etc. Specifically, the following methods can be cited.

[0044] When forming the dense layer by extruding PTFE into a tube at high density, for example, the following operation can be performed.

[0045] PTFE fine powder is mixed with an organic solvent as an extrusion aid and pressurized to form a preform. Then, the preform is formed into a tube shape using an extruder. The formed tube-shaped PTFE is heated to a temperature below the melting point of PTFE to volatilize the organic solvent and dry it. The dried tube-shaped PTFE is heated to a temperature above the melting point of PTFE, and the pores generated by the volatilization of the organic solvent are closed, resulting in a high-density PTFE tube. In addition, the dense layer can be formed by PTFE, which is formed by volatilizing the organic solvent of the tube-shaped PTFE formed by the preform, heating it at a temperature below the melting point of PTFE, and then performing uniaxial or biaxial stretching and densification. If it is compressed and densified after uniaxial or biaxial stretching, it is possible to adjust elongation, tensile properties, and operational wall thickness. The dense layer formed as above can be prepared by using a tube with an outer diameter roughly the same as the inner diameter of the laminated tube to form a core material, and coating the core material with the high-density PTFE tube. The dense layer thus formed may be heated to a temperature not lower than the melting point of PTFE and calcined before being laminated with other layers, or may be laminated with other layers in an uncalcined state.

[0046] When forming the dense layer by winding a high-density PTFE film into a cylindrical shape, for example, the following operation can be performed.

[0047] PTFE fine powder is mixed with an organic solvent as an extrusion aid and pressurized to form a preform. Next, the preform is formed into a film shape using an extruder. The formed film-shaped PTFE is heated to a temperature below its melting point to volatilize the organic solvent and dry it. The dried film-shaped PTFE is heated to a temperature above the melting point of the PTFE to obtain a high-density PTFE film. For example, a tube having an outer diameter roughly the same as the inner diameter of the laminated tube to be produced can be used as a core material, and the high-density PTFE film is wound around the core material to form a dense layer of the laminated tube. The high-density PTFE film can be wound around the core material in a tobacco-like or spiral manner. Alternatively, the dense layer can be formed from a PTFE film that is formed by volatilizing the organic solvent in the film-shaped PTFE formed from the preform, then heating it at a temperature below the melting point of the PTFE and performing uniaxial or biaxial stretching, followed by compression to densify it. In this case, it can also be formed by winding it around a core material. Alternatively, the dense layer may be formed from PTFE, which is formed by wrapping a uniaxially or biaxially stretched PTFE film around a core material and then compressing it from the outer surface through a die or the like to achieve densification. The dense layer thus formed may be heated to a temperature above the melting point of the PTFE and calcined before being laminated with other layers, or may be directly laminated with other layers in an uncalcined state.

[0048] The soft layer is preferably composed of PTFE with a porosity of 20% or greater. PTFE with a porosity of 20% or greater decreases density in proportion to the air contained within the pores of the PTFE resin. In the present invention, the thickness of the soft layer can be appropriately determined based on the required strength of the laminated tube, and is typically approximately 0.10 mm to 2.0 mm.

[0049] The soft layer can be formed, for example, by coating the outside of a tube containing the dense layer with a PTFE tube that has been extruded and then uniaxially or biaxially stretched to a porosity of 20% or more; or by wrapping a uniaxially or biaxially stretched PTFE film around the outside of the tube containing the dense layer. Specifically, the soft layer can be formed using the following methods.

[0050] When forming the soft layer by covering the outer side of the tube including the dense layer with a PTFE tube that has been uniaxially or biaxially stretched to have a porosity of 20% or more, for example, the following method can be used.

[0051] A preformed product made by mixing PTFE fine powder and an organic solvent is put into an extruder and formed into a tube shape. The formed tube-shaped PTFE is heated to a temperature below the melting point to volatilize the organic solvent, and then uniaxially or biaxially stretched at a temperature below the melting point of PTFE to form a PTFE tube with a porosity of 20% or more. The PTFE tube with a porosity of 20% or more prepared in this way is coated on the outside of the tube containing the dense layer prepared as above to form a soft layer. The formed laminated tube can be heated as a whole to a temperature above the melting point of PTFE (e.g., 360°C) and calcined to form an integrated structure.

[0052] When the soft layer is formed by winding a uniaxially or biaxially stretched PTFE membrane having a porosity of 20% or more around a tube including a dense layer, for example, the following operation can be performed.

[0053] A preformed body made by mixing PTFE fine powder and an organic solvent is put into an extruder and formed into a membrane shape. The membrane-shaped PTFE after being formed is heated to a temperature below the melting point to volatilize the organic solvent, and then uniaxially or biaxially stretched at a temperature below the melting point of PTFE to form a PTFE membrane with a porosity of more than 20%. The PTFE membrane with a porosity of more than 20% prepared as above is wound on the outside of the tube containing the dense layer prepared as above to form a soft layer. The winding method of the PTFE membrane on the outside of the tube containing the dense layer can be tobacco winding or spiral winding. The formed laminated tube can be heated as a whole to a temperature above the melting point of PTFE (for example, 360°C) and calcined to form an integrated structure.

[0054] The total porosity of the laminated tube of the present invention is preferably in the range of about 8% or more and about 27% or less. The total porosity of the tube refers to the proportion (percentage) of the volume of the pores contained in the laminated tube as a whole per unit length in the volume of the laminated tube as a whole per unit length. Laminated tubes having more than two layers and a total porosity within the above range have excellent airtightness durability. In the present invention, airtightness durability means that even if the tube is repeatedly bent more than 50,000 times, airtightness or liquid-tightness can be maintained. In the conventional tubes as described above, cracks appear in a part of the tube during repeated bending tests, and the airtightness is reduced. In contrast, the tubes of the present invention have excellent airtightness durability, and the airtightness will not be reduced even if bent more than 50,000 times.

[0055] The total porosity of the manufactured laminated tube can be calculated, for example, as follows. The laminated tube is cut into pieces of unit length (e.g., 10 mm), the inner and outer diameters are accurately measured, and the volume V of the cut laminated tube is calculated. The laminated tube of volume V includes pores of volume p. The weight of the laminated tube of volume V is measured, and the density of the laminated tube (g / cm2) is calculated. 3 When the laminated tube is mainly composed of PTFE, the density of the high-density PTFE is set to 2.2 g / cm3 , the total porosity is calculated by the following formula.

[0056] Total porosity = p / V = 1-(density of stacked tubes / 2.2)

[0057] The laminated tube of the present invention preferably has an indentation depth and a Martens hardness measured on the inner surface of the laminated tube in accordance with ISO 14577-1 that satisfy the following formulas (1) and (2).

[0058] 0.02≤HM 3mN ≤0.38 Formula (1)

[0059] -0.0450 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0010 / μm Formula (2)

[0060] The multi-layer tube of the present invention more preferably has an indentation depth and a Martens hardness measured on the inner surface in accordance with ISO 14577-1 that satisfy the following formulas (3) and (4).

[0061] 0.03≤HM 3mN ≤0.33 Formula (3)

[0062] -0.0400 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0013 / μm Formula (4)

[0063] The multi-layer tube of the present invention preferably has an indentation depth and a Martens hardness measured on the inner surface in accordance with ISO 14577-1 that satisfy the following formulas (5) and (6).

[0064] 0.04≤HM 3mN ≤0.25 Formula (5)

[0065] -0.0300 / μm≤(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )≤-0.0015 / μm Formula (6)

[0066] Among them, D 3mN (μm) and HM 3mN They represent the penetration depth of the indenter and the Martens hardness of the laminated tube when the test force reaches 3 mN during the load application process, D 4mN (μm) and HM 4mNThe values represent the indentation depth when the maximum test force is 4 mN and the Martens hardness of the laminated tube. The above relationship makes it easier to bend the tube with moderate force and less likely to flatten.

[0067] Furthermore, the laminated tube of the present invention preferably has an indenter penetration depth and a Martens hardness measured on the inner surface of the laminated tube in accordance with ISO 14577-1 that satisfy the following formulas (7) and (8).

[0068] 0.02≤HM' 3mN ≤0.38 Formula (7)

[0069] -0.0700 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0020 / μm Formula (8)

[0070] The multi-layer tube of the present invention more preferably has an indentation depth and a Martens hardness measured on the inner surface in accordance with ISO 14577-1 that satisfy the following formulas (9) and (10).

[0071] 0.03≤HM' 3mN ≤0.33 Formula (9)

[0072] -0.0650 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0027 / μm Formula (10)

[0073] The multi-layer tube of the present invention further preferably has an indentation depth and a Martens hardness measured on the inner surface in accordance with ISO 14577-1 that satisfy the following formulas (11) and (12).

[0074] 0.04≤HM 3mN ≤0.25 Formula (11)

[0075] -0.0600 / μm≤(HM' 3mN -HM' 2.5mN ) / (D' 3mN -D' 2.5mN )≤-0.0055 / μm Formula (12)

[0076] Among them, D' 2.5mN (μm) and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN (μm) and HM' 3mNThe values are the indentation depth of the indenter and the Martens hardness of the laminated tube when the maximum test force is 3 mN. The above relationship makes the tube easier to bend and less likely to flatten.

[0077] In addition, it is preferred that the horizontal axis of the graph of the laminated tube of the present invention represents the total porosity (%) of the tube, and the vertical axis represents the Martens hardness HM of the tube. 3mN When , the coordinate point representing the above characteristics enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure.

[0078] More preferably, the laminated tube of the present invention has a horizontal axis on the coordinate graph representing the total porosity (%) of the tube and a vertical axis representing the Martens hardness HM of the tube. 3mN When , the coordinate point representing the above characteristics enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the figure.

[0079] In addition, the laminated tube preferably further satisfies the above-mentioned formula (2), formula (4), formula (6), formula (8), formula (10), or formula (12). If the characteristic value of the laminated tube is within the above-mentioned range, the tube can be easily bent appropriately when it is naturally bent, and the flattening of the bent portion can be further suppressed.

[0080] In addition, it is preferred that the horizontal axis of the multilayer tube of the present invention on the coordinate graph represents the total porosity (%) of the tube and the vertical axis represents the Martens hardness HM' of the tube. 3mN When , the coordinate point representing the above characteristics enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure.

[0081] The laminated tube of the present invention is more preferably a graph in which the horizontal axis represents the total porosity (%) of the tube and the vertical axis represents the Martens hardness HM' of the tube. 3mN When , the coordinate point representing the above characteristics enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the figure.

[0082] In addition, the laminated tube preferably further satisfies the above-mentioned formula (2), formula (4), formula (6), formula (8), formula (10), or formula (12). If the characteristic value of the laminated tube is within the above-mentioned range, the tube can be bent with an appropriate force when it is naturally bent, and the flattening of the bent portion can be further suppressed.

[0083] Example

[0084] Hereinafter, the present invention will be specifically described using examples.

[0085] Example 1

[0086] PTFE fine powder and an organic solvent are mixed in a container, sieved to remove lumps, and then put into a preforming machine to make a preform. The preform is put into an extruder with a barrel diameter of 20 mm and formed into a tube shape. It is then dried at 130°C and calcined in an oven at 350°C to make a high-density PTFE tube. The tube dimensions are 3.75 mm inner diameter and 0.135 mm wall thickness. Next, the high-density PTFE tube is coated on a stainless steel tube with a diameter of 3.7 mm as a core material for standby use. A PTFE membrane with a thickness of 0.10 mm and a porosity of 30% is spirally wound around its periphery in a manner such that the thickness of the PTFE membrane layer is 0.465 mm with a porosity of 30%.

[0087] The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes to integrate the laminate, and then removed from the stainless steel tube to prepare a laminate tube of the present invention having a total porosity of 12%.

[0088] Comparative Example 1

[0089] A PTFE preform was prepared in the same manner as in Example 1 and formed into a tube using an extruder. The preform was then dried at 130°C and calcined in an oven at 350°C to produce a high-density PTFE tube with an inner diameter of 3.75 mm and a wall thickness of 0.06 mm. This high-density PTFE tube was then coated onto a 3.7 mm diameter stainless steel tube serving as a core material and then used for subsequent use. An uncalcined PTFE membrane with a thickness of 0.10 mm and a porosity of 45% was spirally wound around the preform, with the PTFE layer having a porosity of 45% being 0.5 mm thick.

[0090] The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes to integrate the laminate, and then removed from the stainless steel tube to prepare a laminate tube having a total porosity of 40%.

[0091] <Airtightness durability test>

[0092] To confirm the durability of the manufactured laminated tube, an airtight durability test was performed. One end of the manufactured tube was fixed and, in this state, it was repeatedly bent left and right with a curvature radius of 10 mm to confirm whether air leaked from the inside of the laminated tube to the outside (airtightness test). Before 50,000 repeated bends, the airtightness test was performed at intervals of 1 degree for 5,000 times, and then at intervals of 1 degree for 20,000 times. The test was terminated if no air leaked during the airtightness test, even after repeated bends exceeded 200,000 times.

[0093] The laminated tube of the present invention, i.e., the tube of Example 1 with a total porosity of 12%, showed no change in appearance even after completing 200,000 repeated bends in the airtightness durability test, maintaining the same airtightness as before the start of the test. In contrast, the tube of Comparative Example 1 with a total porosity of 40% failed to maintain airtightness after only approximately 40,000 bends.

[0094] Example 2

[0095] PTFE fine powder and additives are mixed in a container, sieved to remove lumps, and then put into a preforming machine to make a preform. The preform is put into an extruder with a barrel diameter of 20mm and formed into a tube shape. Then, it is dried at 130℃ and calcined in an oven at 350℃ to make a high-density PTFE tube with an inner diameter of 3.23mm and a wall thickness of 0.09mm. Next, this high-density PTFE tube is coated on a stainless steel tube with a diameter of 3.2mm as a core material for standby use. A PTFE membrane with a thickness of 0.10mm and a porosity of 30% is spirally wound around its periphery in a manner that the thickness of the PTFE layer is 0.41mm with a porosity of 30%.

[0096] The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes to integrate the laminate, and then removed from the stainless steel tube to prepare a laminate tube of the present invention having a total porosity of 13%.

[0097] Example 3

[0098] PTFE fine powder and additives are mixed in a container, sieved to remove lumps, and then fed into a preformer to form a preform. The resulting preform is fed into an extruder and formed into a tube shape. It is then dried at 130°C and heated to above 360°C for calcination. The resulting high-density PTFE tube has an inner diameter of 3.75mm and a wall thickness of 0.12mm. Separately, a PTFE tube with a porosity of 20% or more is produced. PTFE fine powder and additives are mixed to form a preform, which is then formed into a tube shape using an extruder. The preform is then stretched along the length of the tube at a temperature below 327°C to produce a PTFE tube with a porosity of 20% or more. The resulting tube has a porosity of 52% and a wall thickness of 0.5mm. The resulting high-density PTFE tube is then wrapped around a 3.7mm diameter brass tube serving as a core material and set aside. A PTFE tube with a porosity of 52% is then coated on the outside. The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes to be integrated, and then removed from the brass tube to prepare a multilayer tube of the present invention having a total porosity of 24%.

[0099] Example 4

[0100] PTFE fine powder and additives are mixed in a container, sieved to remove lumps, and then placed in a preforming machine to produce a preform. The resulting preform is placed in an extruder and formed into a tube shape. It is then dried at 130°C and uniaxially stretched to prepare a PTFE tube with a porosity of 70%. In addition to this 70% porosity PTFE tube, a 0.02mm thick PFA membrane is prepared. A 3.7mm diameter stainless steel tube serving as the core material is coated with the 70% porosity PTFE tube and then compressed through a die to form a 0.100mm thick high-density PTFE layer. A 0.02mm thick PFA membrane is wrapped around the outer periphery with tobacco, and then a 0.48mm thick uncalcined PTFE membrane with a thickness of 0.145mm and a porosity of 35% is spirally wrapped around the outer periphery.

[0101] The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes and then removed from the stainless steel tube to prepare a multilayer tube of the present invention having a total porosity of 18%.

[0102] Example 5

[0103] PTFE fine powder and an auxiliary agent are mixed in a container, sieved to remove lumps, and then put into a preforming machine to make a preform. The preform is put into an extruder and formed into a tube shape. Then, it is dried at 130°C and uniaxially stretched to prepare a PTFE tube with a porosity of 70%. After the above-mentioned PTFE tube with a porosity of 70% is coated on a stainless steel tube with a diameter of 3.2mm as a core material, it is compressed through a die to form a high-density PTFE layer with a thickness of 0.100mm. On top of it, an uncalcined PTFE membrane with a thickness of 0.145mm and a porosity of 35% is spirally wound in a manner with a thickness of 0.32mm.

[0104] The PTFE laminate thus prepared was calcined at a temperature of 360° C. or higher for 10 minutes and then removed from the stainless steel tube to prepare a multilayer tube of the present invention having a total porosity of 24%.

[0105] <Instrumented Indentation Hardness Test>

[0106] According to ISO14577-1, an instrumented indentation hardness test is performed on the inner surface side of the laminated tube. In this measurement, the relationship data between the Martens hardness and the indentation depth of the indenter are obtained. The measuring device uses a Shimadzu dynamic ultramicrohardness tester DUH-201S (manufactured by Shimadzu Corporation). The measurement is carried out by a test method that controls the test force. With the long side direction of the laminated tube as the length direction, a long strip with a width of about 2.0 to 2.5 mm is cut from it to make a measurement sample. When measuring a tube-shaped sample, if a thin strip is cut out for measurement, it will not be affected by the radial deflection of the tube, so it is preferred. The cut sample is fixed to a test piece holder with a rigid support body along the indentation direction, and the position is adjusted by a magnifying glass so that the surface of the inner surface side of the tube of the sample is vertically abutted against the indenter. The measurement conditions are set as follows, and the other conditions and operations are in accordance with the description of ISO14577-1.

[0107] Measurement Condition 1

[0108] Measurement mode: Indentation test (load-unload test)

[0109] Measuring indenter: Triangular pyramid indenter with an edge angle of 115° (Berkovich type)

[0110] Maximum test force: 4mN

[0111] Minimum test force: 0.02mN

[0112] Load speed: 0.1463mN / sec

[0113] Load holding time: 10 sec

[0114] Uninstall hold time: 10 seconds

[0115] Objective lens magnification: 50 times

[0116] Measurement temperature: 23℃±2℃

[0117] Measurement Condition 2

[0118] Measurement mode: Indentation test (load-unload test)

[0119] Measuring indenter: Triangular pyramid indenter with an edge angle of 115° (Berkovich type)

[0120] Maximum test force: 3mN

[0121] Minimum test force: 0.02mN

[0122] Load speed: 0.1463mN / sec

[0123] Load holding time: 10 sec

[0124] Uninstall hold time: 10 seconds

[0125] Objective lens magnification: 50 times

[0126] Measurement temperature: 23℃±2℃

[0127] <Bending Test-Determination of Deformed Dimensions>

[0128] The bending test is measured according to method A of JIS K6330-9:2003. The bending radius (C×1 / 2) of the laminated tube during measurement is set to 10 mm. The average outer diameter D of the laminated tube as the object is measured using a laser outer diameter measuring device. The interval between the two parallel guide plates is made greater than (C+2D) in advance, and the laminated tube is set between the guide plates. Then, in this state, the interval between the guide plates is reduced to (C+2D). In a state where the interval between the guide plates is (C+2D), the deformation of the laminated tube is measured at the bent portion of the laminated tube. The deformed outer diameter dimension T (short diameter) of the laminated tube is measured using a laser outer diameter measuring device to determine the T / D value. The T / D value is used as the bending flatness. The measurement is performed at 23°C±2°C.

[0129] <Bending test force measurement>

[0130] Bending force measurements were performed in accordance with JIS K7171:2016. The test was performed at a support distance of 64 mm and a test speed of 500 mm / min. The test piece length was 80 mm and the temperature was 23°C ± 2°C. The test force at a deflection of 25 mm was recorded as the bending force (N).

[0131] The results of various tests performed on the pipes of each example are shown in Tables 1 and 2. The results of the instrumented indentation hardness test under measurement condition 1 are shown in Table 1, and the results of the instrumented indentation hardness test under measurement condition 2 are shown in Table 2.

[0132] Table 1

[0133] Example 1 Example 2 Example 3 Example 4 Example 5 Total porosity ％ 12 13 24 18 24 <![CDATA[HM 3mN ]]> 0.23 0.044 0.30 0.13 0.037 <![CDATA[D 3mN ]]> 7.01 16.20 6.27 9.35 17.79 <![CDATA[HM 4mN ]]> 0.16 0.036 0.17 0.11 0.026 <![CDATA[D 4mN ]]> 9.82 20.72 8.89 11.93 24.41 <![CDATA[(HM 4mN -HM 3mN ) / (D 4mN -D 3mN )]]> <![CDATA[×10 -2 ]]> -2.55 -0.18 -3.84 -0.94 -0.16 Bending test force N 2.30 1.30 2.61 2.20 1.20 Bending flatness ％ 86 86 91 82 82

[0134] Table 2

[0135] Example 1 Example 2 Example 3 Example 4 Example 5 Total porosity ％ 12 13 24 18 24 <![CDATA[HM′ 2.5mN ]]> 0.31 0.067 0.37 0.17 0.05 <![CDATA[D′ 2.5mN ]]> <![CDATA[HM′ 3mN ]]> 0.23 0.046 0.29 0.14 0.041 <![CDATA[D′ 3mN ]]> 7.00 15.90 6.34 8.89 16.85 <![CDATA[(HM′ 3mN -HM′ 2.5mN ) / (D′ 3mN -D′ 2.5mN )]]> <![CDATA[×10 -2 ]]> -5.31 -0.55 -6.93 -1.92 -0.38 Bending test force N 2.30 1.30 2.61 2.20 1.20 Bending flatness ％ 86 86 91 82 82

[0136] in addition, Figure 2 and Figure 3 The horizontal axis is the total porosity of the tube (%), and the vertical axis is the Martens hardness HM of the tube. 3mN or HM' 3mN Picture. Figure 2The graph shows a quadrilateral formed by connecting coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) with dotted lines and coordinate points representing the characteristics of each embodiment. Figure 3 A quadrilateral formed by connecting coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) with dotted lines and coordinate points representing the characteristics of each embodiment are drawn on the graph.

[0137] The laminated tubes of Examples 1 to 5 of the present invention can be bent with moderate force, suppressing flattening of the tube at the bend. In airtightness durability testing, the tubes of Examples of the present invention showed no change in appearance even after 200,000 repeated bends, maintaining the same airtightness as before the test.

[0138] Industrial applicability

[0139] The laminated tube of the present invention exhibits chemical resistance, heat resistance, flexibility, and excellent airtightness and durability. Therefore, it can be used for fluid transportation in locations subject to repeated bending loads. It is particularly suitable for applications in the medical, pharmaceutical, and semiconductor industries, where chemical resistance and cleanability are required.

[0140] Explanation of symbols

[0141] 1. Laminated tube of the present invention

Claims

1. A laminated tube, characterized in that: Contains polytetrafluoroethylene as the main component, The horizontal axis of the graph is the total porosity (%) of the tube, and the vertical axis is the Martens hardness HM of the tube. 3mN When the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure, Among them, HM 3mN When the inner surface of a tube is measured in accordance with ISO 14577, the Martens hardness is expressed when the test force reaches 3 mN during the application of the load with a maximum test force of 4 mN.

2. The laminated tube according to claim 1, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy the formula (2), -0.0450 / μm ≤ (HM 4mN - HM 3mN ) / (D 4mN - D 3mN ) ≤ -0.0010 / μm Equation (2) Among them, D 3mN and HM 3mN They represent the penetration depth of the indenter when the test force reaches 3 mN during the load application process and the Martens hardness of the laminated tube, D 4mN and HM 4mN They represent the indentation depth of the indenter and the Martens hardness of the laminated tube when the maximum test force is 4 mN. 3mN and D 4mN The unit is μm.

3. The laminated tube according to claim 1, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy the formula (4), -0.0400 / μm ≤ (HM 4mN - HM 3mN ) / (D 4mN - D 3mN ) ≤ -0.0013 / μm Equation (4) Among them, D 3mN and HM 3mN They represent the penetration depth of the indenter when the test force reaches 3 mN during the load application process and the Martens hardness of the laminated tube, D 4mN and HM 4mN They represent the indentation depth of the indenter and the Martens hardness of the laminated tube when the maximum test force is 4 mN. 3mN and D 4mN The unit is μm.

4. The laminated tube according to claim 1, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO14577 satisfy equation (6): -0.0300 / μm ≤ (HM 4mN - HM 3mN ) / (D 4mN - D 3mN ) ≤ -0.0015 / μm Equation (6) Among them, D 3mN and HM 3mN They represent the penetration depth of the indenter when the test force reaches 3 mN during the load application process and the Martens hardness of the laminated tube, D 4mN and HM 4mN They represent the indentation depth of the indenter and the Martens hardness of the laminated tube when the maximum test force is 4 mN. 3mN and D 4mN The unit is μm.

5. A laminated tube, characterized in that: Contains polytetrafluoroethylene as the main component, The horizontal axis of the graph is the total porosity (%) of the tube, and the vertical axis is the Martens hardness HM' of the tube. 3mN When the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c (25, 0.38) and d (25, 0.03) on the figure, Among them, HM' 3mN This indicates the Martens hardness when the inner surface of a tube is measured according to ISO 14577 and the maximum test force is 3 mN.

6. The laminated tube according to claim 5, characterized in that The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO14577 satisfy equation (8): -0.0700 / μm ≤ (HM’ 3mN -HM’ 2.5mN ) / (D’ 3mN -D’ 2.5mN ) ≤ -0.0020 / μm Equation (8) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

7. The laminated tube according to claim 5, characterized in that The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy the formula (10), -0.0650 / μm ≤ (HM’ 3mN - HM’ 2.5mN ) / (D’ 3mN - D’ 2.5mN ) ≤ -0.0027 / μm Equation (10) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

8. The laminated tube according to claim 5, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy equation (12): -0.0600 / μm ≤ (HM’ 3mN - HM’ 2.5mN ) / (D’ 3mN - D’ 2.5mN ) ≤ -0.0055 / μm Equation (12) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

9. A laminated tube, characterized in that: Contains polytetrafluoroethylene as the main component, The horizontal axis of the graph is the total porosity (%) of the tube, and the vertical axis is the Martens hardness HM' of the tube. 3mN When the coordinate point representing the characteristics of the laminated tube enters the quadrilateral formed by connecting the four coordinate points a (7.5, 0.25), b (8, 0.02), c' (25, 0.33) and d (25, 0.03) on the figure, Among them, HM' 3mN This indicates the Martens hardness when the inner surface of a tube is measured according to ISO 14577 and the maximum test force is 3 mN.

10. The laminated tube according to claim 9, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO14577 satisfy equation (8), -0.0700 / μm ≤ (HM’ 3mN - HM’ 2.5mN ) / (D’ 3mN - D’ 2.5mN ) ≤ -0.0020 / μm Equation (8) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

11. The laminated tube according to claim 9, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy the formula (10), -0.0650 / μm ≤ (HM’ 3mN - HM’ 2.5mN ) / (D’ 3mN - D’ 2.5mN ) ≤ -0.0027 / μm Equation (10) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

12. The laminated tube according to claim 9, wherein: The indentation depth of the indenter and the Martens hardness of the laminated tube measured according to ISO 14577 satisfy equation (12): -0.0600 / μm ≤ (HM’ 3mN - HM’ 2.5mN ) / (D’ 3mN - D’ 2.5mN ) ≤ -0.0055 / μm Equation (12) Among them, D' 2.5mN and HM' 2.5mN The indenter penetration depth and the Martens hardness of the laminated tube are shown in D', respectively, when the test force reaches 2.5 mN during the load application process. 3mN and HM' 3mN They represent the indentation depth of the indenter when the maximum test force reaches 3 mN and the Martens hardness of the laminated tube, respectively. 2.5mN and D' 3mN The unit is μm.

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