Multilayer tube

Abstract

Provided is a multilayer tube having a small kink point radius and enhanced bending durability. A multilayer tube 10 is a hollow tube in which a plurality of layers are layered in the thickness direction. The plurality of layers include: a first layer 11, which is on the inner peripheral side and is formed of a modified adhesive fluororesin; a second layer 12 having gas barrier properties, formed on an outer periphery of the first layer 11, and formed using an ethylene vinyl alcohol copolymer resin modified with an acetoacetyl group; and a third layer 13 formed on an outer periphery of the second layer 12 and formed with a modified polyolefin resin modified with an acidic functional group. The ratio of the wall thickness of the second layer 12 to the overall wall thickness of the tube including the first layer 11, the second layer 12, and the third layer 13 is 6 / 10 or more.

Description

Multilayer Tube

[0001] The present invention relates to a multi-layer tube.

[0002] Multilayer tubes are used, for example, as ink supply tubes. It is known that if the air outside the multilayer tube penetrates the thickness of the multilayer tube and reaches the ink inside the multilayer tube, it can affect the properties of the ink and the accuracy of application. For this reason, gas barrier properties are an important factor for multilayer tubes used as ink supply tubes. To ensure gas barrier properties, ethylene-vinyl alcohol copolymer (hereinafter also referred to as EVOH) is used, for example, as a material for forming the multilayer tube.

[0003] Patent Document 1 discloses a multilayer tube that is composed of multiple layers including an antistatic layer composed of a thermoplastic resin and an antistatic agent, and a gas barrier layer composed of a gas barrier resin, where the gas barrier resin is a saponified product of an ethylene-vinyl acetate copolymer.

[0004] Patent Document 2 discloses an ink supply tube having an inner layer made of an ethylene-tetrafluoroethylene copolymer resin or the like, a first intermediate layer made of a polyamide resin, a second intermediate layer made of an ethylene-vinyl alcohol copolymer resin, a third intermediate layer made of a polyolefin resin, and an outer layer made of a thermoplastic resin or an elastomer.

[0005] Patent Document 3 discloses an ink supply tube having a first layer formed of an ethylene-tetrafluoroethylene copolymer resin, a second layer formed of a modified ethylene-tetrafluoroethylene copolymer resin, a third layer formed of a polyamide resin or the like, a fourth layer formed of an ethylene-vinyl alcohol copolymer resin, and a fifth layer formed of a modified polypropylene resin.

[0006] JP 2007-160899 A International Publication No. 2016 / 186111 JP 2021-94857 A

[0007] EVOH has extremely hard properties compared to other resin materials for tubes, and therefore tubes using EVOH to enhance the gas barrier properties are also hard, resulting in a large kink radius and low flex durability. If the flex durability of a tube is low, there is a problem that when the tube is used in a part that is repeatedly bent, such as a movable pipe, it is prone to cracking due to bending. If a tube cracks, its gas barrier properties will deteriorate. In particular, as printing speeds in inkjet printers continue to increase, high flex durability is required for ink supply tubes used in inkjet printers.

[0008] An object of the present invention is to provide a multi-layer tube having a small kink radius and improved bending durability.

[0009] The multi-layer tube according to the present invention is a hollow tube having a plurality of layers laminated in the thickness direction, the plurality of layers comprising: a first inner layer formed of a modified adhesive fluororesin; a second gas barrier layer formed on the outer periphery of the first layer from an ethylene-vinyl alcohol copolymer resin modified with an acetoacetyl group; and a third layer formed on the outer periphery of the second layer from a modified polyolefin resin modified with an acidic functional group, wherein the ratio of the wall thickness of the second layer to the overall wall thickness of the tube including the first, second, and third layers is 6 / 10 or more.

[0010] According to the present invention, it is possible to provide a multilayer tube having a small kink point radius and improved bending durability.

[0011] It is a perspective view of the ink supply tube according to the present embodiment, with a part thereof removed.It is a diagram showing a schematic configuration of a bending stiffness test device.It is a diagram showing bending stiffness test results.

[0012] (Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0013] (Configuration of Multilayer Tube 10) Fig. 1 shows a multilayer tube 10 having a three-layer structure according to this embodiment. The multilayer tube 10 has a hollow structure. The multilayer tube 10 comprises, in order from the inner periphery, a first layer 11, a second layer 12, and a third layer 13. The first layer 11 is disposed on the innermost periphery, the second layer 12 is formed on the outer periphery of the first layer 11, and the third layer 13 is formed on the outer periphery of the second layer 12.

[0014] The first layer 11 is a modified adhesive fluororesin. Known modified adhesive fluororesins can be used to form the first layer 11, and include homopolymers or copolymers, such as copolymers having ethylene (hereinafter also referred to as "E") units and tetrafluoroethylene (hereinafter also referred to as "TFE") units (hereinafter also referred to as "ethylene-tetrafluoroethylene copolymer" or "ETFE"), copolymers having TFE units and perfluoro(alkyl vinyl ether) units, copolymers having TFE units and hexafluoropropylene units, and polymers having vinylidene fluoride units, into which one or more adhesive functional groups have been introduced at least at the end or side chain. Examples of adhesive functional groups include carboxyl groups, carboxylic acid anhydride residues, epoxy groups, hydroxyl groups, isocyanate groups, ester groups, amide groups, aldehyde groups, amino groups, hydrolyzable silyl groups, cyano groups, carbon-carbon double bonds, sulfonic acid groups, and ether groups.

[0015] The above-mentioned modified adhesive fluororesin has excellent chemical resistance and low water absorption, making it ideal as a protective material for the gas barrier layer and preventing a decrease in the gas barrier performance of the gas barrier layer. Among them, modified ETFE is preferred because of its chemical resistance and the flexibility required for a tube.

[0016] The second layer 12 is formed of an ethylene-vinyl alcohol copolymer resin modified with an acetoacetyl group (hereinafter referred to as a "modified EVOH resin").

[0017] The modified EVOH resin contains vinyl alcohol units represented by the following formula (1), vinyl acetoacetate units represented by the following formula (2), and ethylene units represented by the following formula (3).

[0018]

[0019]

[0020]

[0021] The modified EVOH resin has a flexural modulus of, for example, 200 MPa (ISO178 23°C, 50% RH, 2 mm / min). The oxygen permeability coefficient is, for example, 120 cc. 20 μm / m ２ . day. atm] (20°C, 65% RH), and 0.27 [cc. 20 μm / m ２ Although this value is larger than the value for [0.5 . day. atm], it indicates that the film has gas barrier properties against oxygen.

[0022] The second layer 12 is formed of a modified EVOH resin and therefore has gas barrier properties. The higher the ratio of acetoethylene units, the higher the flexibility of the EVOH resin and the lower the gas barrier properties. The higher the ratio of vinyl acetoacetate units, the lower the flexibility of the EVOH resin and the higher the gas barrier properties. Considering the balance between flexibility and gas barrier properties, the preferred ethylene composition ratio is 20 mol% or more and 60 mol% or less. Furthermore, from the viewpoints of flexibility and gas barrier properties, the ethylene composition ratio in this embodiment is desirably 29 mol% or more and 45 mol% or less.

[0023] The third layer 13 is made of a modified polyolefin resin. The modified polyolefin resin is a polyethylene resin such as high-density polyethylene resin (HDPE), low-density polyethylene resin (LDPE), linear low-density polyethylene resin (LLDPE), or very low-density polyethylene resin (VLDPE), or a polyolefin resin such as a polypropylene resin, modified with an acidic functional group, preferably modified with a carboxylic acid or a derivative thereof, and can be obtained, for example, by introducing acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, anhydrides of these acids, or esters of these acids into a polyolefin resin.

[0024] The modified polyolefin resin forming the third layer 13 is modified with an acidic functional group, and thus can firmly adhere to the modified EVOH resin. The modified polyolefin resin is used by co-extrusion with, for example, a modified adhesive fluororesin. In this case, it is preferable to use a modified polypropylene resin because the molding temperature is high.

[0025] In the multi-layer tube 10, the ratio of the wall thickness of the second layer 12 to the total wall thickness of the tube including the first layer 11, second layer 12, and third layer 13 is 6 / 10 or more. For example, when the total wall thickness of the tube is 1.0 mm, the wall thickness of the second layer 12 is 0.6 mm or more. The combined wall thicknesses of the first layer 11 and the third layer 13 can be appropriately selected within a range of 0.4 mm or less. For example, when the wall thickness of the second layer 12 is 0.6 mm, the wall thickness of the first layer 11 can be 0.1 mm and the wall thickness of the third layer can be 0.3 mm.

[0026] Preferably, in the multi-layer tube 10, the ratio of the wall thickness of the second layer 12 to the total wall thickness of the tube including the first layer 11, the second layer 12, and the third layer 13 is 7 / 10 or more, more preferably 8 / 10 or more. For example, when the total wall thickness of the tube is 1.0 mm, the wall thickness of the second layer 12 is preferably 0.7 mm or more, more preferably 0.8 mm or more. The combined wall thickness of the first layer 11 and the third layer 13 is preferably 0.3 mm or less, more preferably 0.2 mm or less, and can be appropriately selected within this range. For example, when the wall thickness of the second layer 12 is 0.7 mm, the wall thickness of the first layer 11 can be 0.1 mm, and the wall thickness of the third layer can be 0.2 mm. For example, when the wall thickness of the second layer 12 is 0.8 mm, the wall thickness of the first layer 11 can be 0.1 mm, and the wall thickness of the third layer can be 0.1 mm.

[0027] Since the second layer 12 is made of a modified EVOH resin, the gas barrier properties of the multi-layer tube 10 can be ensured.

[0028] Since the first layer 11 is formed of the modified ETFE resin, the multilayer tube 10 has chemical resistance and low moisture permeability. For example, when the multilayer tube 10 is used as an ink supply tube, ink color residue can be suppressed.

[0029] The third layer 13 is formed of a modified polyolefin resin having an acidic functional group introduced therein, thereby improving the bonding strength with the second layer 12. Furthermore, by forming the third layer 13 from a modified polyolefin resin having an acidic functional group introduced therein, a decrease in transparency is suppressed. For example, when the multilayer tube 10 is used as an ink supply tube, the ink flowing inside can be more easily observed from the outside. Forming the third layer 13 from a modified polyolefin resin improves moldability.

[0030] (Actions and Effects of Multilayer Tube 10) The multilayer tube 10 of this embodiment has a wall thickness of the second layer 12, which is made of a modified EVOH resin and has a ratio of the wall thickness of the second layer 12 to the overall wall thickness of the tube including the first layer 11, the second layer 12, and the third layer 13 of 6 / 10 or more.

[0031] The modified EVOH resin constituting the second layer 12 is softer than EVOH resin and has gas barrier properties. Because modified EVOH resin, rather than EVOH resin, is used for the second layer 12, which is intended to provide gas barrier properties, the multi-layer tube 10 does not become too hard. Furthermore, by setting the thickness of the second layer 12, which uses modified EVOH resin, within the above-described range, the gas barrier properties of the multi-layer tube 10 can be ensured. The multi-layer tube 10 of this embodiment is softer than a multi-layer tube using EVOH resin as a gas barrier layer. Therefore, the multi-layer tube 10 of this embodiment has a small kink point radius and enhanced flexural durability.

[0032] The multilayer tube 10 of this embodiment can be used to transport fluids such as liquids or gases containing water or organic solvents, or powdery materials. The second layer 12 ensures gas barrier properties in the multilayer tube 10, thereby preventing oxidation of fluids or vaporization of solvents remaining inside the multilayer tube 10. The multilayer tube 10 of this embodiment is particularly applicable to ink supply tubes, which require gas barrier properties. Both water-based and oil-based inks can be supplied. The multilayer tube 10 of this embodiment has a small kink point radius and high bending durability, making it particularly suitable for use as an ink supply tube for inkjet printers. This allows for longer replacement intervals and installation in narrow spaces, especially in inkjet printers where printing speeds are increasing.

[0033] (Method for Manufacturing the Multilayer Tube 10) Next, a method for manufacturing the multilayer tube 10 configured as described above will be described. For example, the multilayer tube 10 can be molded in a single process by simultaneously extruding the three types of resin that make up the first layer 11, the second layer 12, and the third layer 13 and laminating them into a cylindrical shape. Alternatively, after the first layer 11, which will become the inner layer, is formed in an inner layer extruder, the second layer 12 can be formed on the outer peripheral surface of this first layer 11 in an outer layer extruder, and the third layer 13 can be further formed on the outer peripheral surface of the second layer 12 in the outer layer extruder.

[0034] EXAMPLES Next, examples of the multi-layer tube 10 according to the above-described embodiment and comparative examples will be described.

[0035] Here, the first layer 11 was the innermost layer, and the second and third layers 12 and 13 were formed from the outside of the first layer by coextrusion molding to produce a sample multilayer tube according to Example 1 having the configuration shown in Table 1. The first layer 11 was made of a modified ETFE resin. The second layer 12 was made of a modified EVOH resin. The third layer 13 was made of a modified polyolefin resin modified with an acidic functional group. The three-layer multilayer tube was formed by simultaneously extruding three types of resin by coextrusion molding. The multilayer tubes all had an outer diameter of 6 mm and an inner diameter of 4 mm. The total thickness of the first layer 11 to the third layer 13 was 1 mm (i.e., (6 mm - 4 mm) / 2 = 1 mm), and the thicknesses of the first layer 11, second layer 12, and third layer 13 were as shown in Table 1.

[0036] In the same manner as in Example 1, the thickness of each layer was changed as shown in Table 1, and multilayer tube samples according to Examples 2, 3, Comparative Examples 4, and 5 were prepared.

[0037] A sample of a multilayer tube according to Comparative Example 1 having the configuration shown in Table 1 was prepared using modified ETFE resin as the material for the first layer, PA612 as the material for the second layer, EVOH resin as the material for the third layer, PA612 as the material for the fourth layer, and modified polyolefin as the material for the fifth layer.

[0038] For the multi-layer tube according to Comparative Example 2, a commercially available multi-layer tube having the structure shown in Table 1 was used.

[0039] A sample of a multilayer tube according to Comparative Example 3 having the configuration shown in Table 1 was produced using a modified ETFE resin as the material for the first layer and a mixture of PA11 and PA12 as the material for the second layer.

[0040] As shown in Table 1, the multi-layer tube of Example 1 has a second layer formed of a modified EVOH resin, and the ratio of the wall thickness of the second layer (0.6 mm) to the total wall thickness of the tube including the first, second, and third layers (1.0 mm) is 6 / 10. The multi-layer tube of Example 2 has a wall thickness of the second layer (0.7 mm) to the total wall thickness of the tube (1.0 mm) is 7 / 10. The multi-layer tube of Example 3 has a wall thickness of the second layer (0.8 mm) to the total wall thickness of the tube (1.0 mm) is 8 / 10. The multi-layer tubes of Comparative Examples 1 to 3 do not have a layer formed of a modified EVOH resin. The multi-layer tubes of Comparative Examples 4 and 5 have a second layer formed of a modified EVOH resin, but the ratio of the wall thickness of the second layer to the total wall thickness of the tube (1.0 mm) is less than 6 / 10.

[0041]

[0042] A total of eight types of multilayer tubes, namely Examples 1 to 3 and Comparative Examples 1 to 5, each having the configuration shown in Table 1 above, were evaluated for bending rigidity, gas barrier properties, bending durability, and transparency. The results of these evaluations are shown in Table 2 and explained below.

[0043] (Bending Stiffness Test) Bending stiffness tests were conducted on the multilayer tube samples of Examples 1 to 3 and Comparative Examples 1 to 5. The bending stiffness tests were conducted using a bending stiffness tester 31 shown in FIG. 2. Each multilayer tube sample was first left to stand in a constant temperature and humidity chamber (23°C, 50% RH) for at least 24 hours and then attached to the bending stiffness tester 31. The multilayer tube was cut to a length calculated by the formula: length (mm) = π(R + OD / 2) + (2 × OD). Here, R is the tube bending radius (mm) at the start of the test, and OD is the tube outer diameter (mm), which was set to 336 mm in this test. The movable part 33 mounted on a rail was moved toward the fixed part 32 at a speed of 100 mm / min to gradually bend the multilayer tube 10, and the bending radius (mm) versus bending load (N) was measured.

[0044] 3 shows the results of the bending stiffness test. The vertical axis represents the bending load (N) and the horizontal axis represents the bending radius (mm). Example 1 is represented by point x, Example 2 by graph a, Example 3 by graph b, Comparative Example 1 by graph c, Comparative Example 2 by graph d, Comparative Example 3 by graph e, Comparative Example 4 by graph f, and Comparative Example 5 by graph g.

[0045] The kink point radii of the multilayer tubes of Examples 1 to 3 and Comparative Examples 1 to 5 were examined. The kink point radius was the bending radius of the multilayer tube 10 when a kink occurred in the multilayer tube 10. Five tests were conducted, and the average of the kink point radii of each Example and Comparative Example was calculated. A kink point radius smaller than that of the multilayer tube of Comparative Example 1 (11.0 mm or less) was marked with "◎", a kink point radius equivalent to that of the multilayer tube of Comparative Example 1 (more than 11.0 mm but not more than 13.6 mm) was marked with "◯", and a kink point radius larger than that of the multilayer tube of Comparative Example 1 (more than 13.6 mm) was marked with "X". The results are shown in the "Bending Rigidity" column in Table 2.

[0046] In Figure 3, point x indicates the kink point radius of the multilayer tube of Example 1. The dashed line labeled "13.6 mm (Comparative Example 1)" in Figure 3 indicates the kink point radius of Comparative Example 1. As shown in Figure 3, it was confirmed that the multilayer tubes of Examples 2 to 3 had smaller peak bending radii on the graph than, for example, the multilayer tube of Comparative Example 1. As shown in Table 2, it was confirmed that the multilayer tubes of Examples 1 to 3 had smaller kink point radii than the multilayer tube of Comparative Example 2. These results confirm that the multilayer tubes of Examples 1 to 3 are less likely to break than the multilayer tubes of Comparative Examples 1 and 2.

[0047] (Gas Barrier Property Test) A gas barrier property test was conducted on the multilayer tubes of Examples 1 to 3 and Comparative Examples 1 and 3. The dissolved oxygen saturation rate in the gas barrier property test was measured using a dissolved oxygen meter (TD-51 [polarographic method], Toko Chemical Research Institute, Inc.). In the gas barrier property test, degassed toluene solvent was poured into each multilayer tube sample, both ends were sealed, and the tube was left to stand at a temperature of 23°C and a humidity of 50%, and the dissolved oxygen saturation rate of the degassed toluene solvent in the multilayer tube was measured to evaluate the gas barrier property. The dissolved oxygen saturation rate was measured 7 days after the start of the test. The dissolved oxygen saturation rate was calculated using the following formula, where Omin is the amount of dissolved oxygen in toluene degassed until the dissolved oxygen level stabilized, Omax is the amount of dissolved oxygen in toluene saturated with oxygen, and Otest is the amount of dissolved oxygen in the gas barrier test. Dissolved oxygen saturation (%) = (Otest - Omin) / (Omax - Omin) x 100 Toluene was degassed by reducing the pressure under ultrasonic irradiation. Oxygen-saturated toluene was prepared by aerating the toluene until the increase in the amount of dissolved oxygen subsided and stabilized. The lower the dissolved oxygen saturation, the higher the gas barrier property of the multilayer tube.

[0048] For the multilayer tubes of Examples 1 to 3 and Comparative Examples 1 and 3, the dissolved oxygen saturation rates 7 days after the start of the gas barrier test are shown in Table 2. Here, the reference values ​​for the dissolved oxygen saturation rate 7 days after the start of the gas barrier test were set at 50% and 10%, with a result of 10% or less being marked with "◎", a result of more than 10% and 50% or less being marked with "◯", and a result of more than 50% being marked with "×". The results are shown in the "Gas barrier property" column in Table 2.

[0049] As shown in Table 2, it was confirmed that the gas barrier properties of the multilayer tubes of Examples 1 to 3 were as good as that of the multilayer tube of Comparative Example 1.

[0050] (Flexural Durability Test) A flexural durability test was conducted on the multilayer tubes of Examples 1 to 3, Comparative Examples 1, 2, 4, and 5. In the flexural durability test, a sample of each multilayer tube of Examples 1 to 3, Comparative Examples 1, 2, 4, and 5 was attached to a flexural durability tester, and the sample was bent under the following conditions: test temperature 23°C, sample length 300 mm, no enclosed liquid, curvature when bent R40, bending speed 300 times / min, and stroke length 140 mm, and the number of flexes until cracks occurred was counted. Here, one flex was counted as one round trip.

[0051] Table 2 shows the number of flexing cycles required for cracking to occur for the multilayer tubes of Examples 1 to 3, Comparative Examples 1, 2, 4, and 5. Here, the standard number of flexing cycles required for cracking to occur was set at 470,000, and a result exceeding the standard value was marked with "Good," and a result equal to or less than the standard value was marked with "Poor." The results are shown in the "Flexural durability" column in Table 2.

[0052] As shown in Table 2, it was confirmed that the multi-layer tubes of Examples 1 to 3 had better flexural durability than the multi-layer tubes of Comparative Examples 1, 2, 4, and 5.

[0053] (Transparency Test) A transparency test was conducted on the multilayer tube samples of Examples 1 to 3 and Comparative Examples 1 to 5. The transparency test was conducted by sealing toluene in each multilayer tube sample and determining whether a level gauge could detect (react to) the liquid level of the sealed toluene. A level gauge (EE-SPX613, manufactured by Omron Corporation) was used for the evaluation, and the evaluation was conducted with the sensitivity set to Low.

[0054] For the multilayer tubes of Examples 1 to 3 and Comparative Examples 1 to 5, whether or not there was a reaction in the level gauge is shown in Table 2. Here, if there was a reaction in the level gauge, it was marked with "O", and if there was no reaction in the level gauge, it was marked with "X". The results were recorded in the "Transparency" column in Table 2.

[0055] As shown in Table 2, it was confirmed that the transparency of the multilayer tubes of Examples 1 to 3 was as good as that of Comparative Examples 2 to 5.

[0056]

[0057] As described above, the multi-layer tubes of Examples 1 to 3 showed good results in terms of flexural rigidity, gas barrier property, flexural durability, and transparency. The multi-layer tube of Comparative Example 1 had good flexural rigidity and gas barrier property, but poor flexural durability and transparency. The multi-layer tube of Comparative Example 2 had good transparency, but poor flexural rigidity and flexural durability. The multi-layer tube of Comparative Example 3 had good flexural rigidity and transparency, but poor gas barrier property. The multi-layer tube of Comparative Example 4 had good transparency, but poor flexural rigidity and flexural durability. The multi-layer tube of Comparative Example 5 had good transparency, but poor flexural rigidity and flexural durability. From these results, it can be said that the multi-layer tubes of Examples 1 to 3 were evaluated more highly overall than the multi-layer tubes of Comparative Examples 1 to 5.

[0058] The present invention is not limited to the above-described embodiment and can be modified as appropriate within the spirit and scope of the present invention. An innermost layer made of unmodified ethylene-tetrafluoroethylene copolymer resin may be further provided on the inner circumferential side of the first layer 11. An intermediate layer made of polyamide or the like may be further provided between the first layer 11 and the second layer 12.

[0059] REFERENCE SIGNS LIST 10 Multilayer tube 11 First layer 12 Second layer 13 Third layer 31 Bending stiffness test device 32 Fixed part 33 Movable part

Claims

1. A multi-layer tube comprising a hollow tube having a plurality of layers laminated in the thickness direction, the plurality of layers comprising: a first layer on the inner periphery formed of a modified adhesive fluororesin; a second layer having gas barrier properties formed on the outer periphery of the first layer of an ethylene-vinyl alcohol copolymer resin modified with an acetoacetyl group; and a third layer formed on the outer periphery of the second layer of a modified polyolefin resin modified with an acidic functional group, the ratio of the wall thickness of the second layer to the overall wall thickness of the tube including the first layer, the second layer, and the third layer being 6 / 10 or more.

2. The multi-layer tube according to claim 1, wherein the ratio of the wall thickness of said second layer to the total wall thickness of said tube including said first layer, said second layer, and said third layer is 7 / 10 or more.

3. The multi-layer tube according to claim 1, wherein the ratio of the wall thickness of said second layer to the total wall thickness of said tube including said first layer, said second layer, and said third layer is 8 / 10 or more.

4. The multi-layer tube according to claim 1, wherein the acetoacetyl-modified ethylene-vinyl alcohol copolymer resin contains vinyl alcohol units represented by the following formula (1), vinyl acetoacetate units represented by the following formula (2), and ethylene units represented by the following formula (3).

5. The multi-layer tube according to any one of claims 1 to 4, wherein the modified adhesive fluororesin is a modified ethylene-tetrafluoroethylene copolymer resin.

6. The multi-layer tube according to any one of claims 1 to 4, wherein the modified polyolefin resin is a modified polypropylene resin.

7. A multi-layer tube according to any one of claims 1 to 4, wherein the modified adhesive fluororesin is a modified ethylene-tetrafluoroethylene copolymer resin, and the modified polyolefin resin is a modified polypropylene resin.

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