JP4995471B2 - Medical tube - Google Patents

Description

  The present invention relates to a medical tube, and more particularly, to a medical tube suitable for medical use that is used when a medical solution or the like is transported by crushing the tube.

  Because of its excellent transparency, mechanical strength, and flexibility, medical tubes made of soft polyvinyl chloride are often used. However, when a drug such as nitroglycerin or diazepam is infused, these tubes are adsorbed on the tube. . In addition, some soft polyvinyl chlorides contain plasticizers such as DEHP (diethylhexyl phthalate) to give flexibility, and drugs containing surfactants as drug solubilizers, such as anticancer drugs In the case of infusion of pepsid, taxol, fat emulsion, anesthetic propofol, etc., the plasticizer is eluted from the tube, and the influence of the plasticizer on the living body and the hardening of the tube over time becomes a problem. In addition, for materials containing halogenated polymers such as polyvinyl chloride and chlorinated polyethylene, there are concerns about the generation of dioxins during incineration, and in view of recent environmental problems, the emergence of non-halogen-based alternative materials is desired. .

Recently, in order to deal with these problems, a tube material containing polybutadiene that hardly absorbs a drug (see Patent Document 1) and a tube material containing a styrene elastomer that does not contain a plasticizer (see Patent Documents 2 and 3). Has been developed and used.
JP-A-6-184360 JP 2001-30425 A JP 2003-205033 A

  However, the tube formed from the material disclosed in Patent Document 1 is inferior in breaking strength as compared with a conventional soft polyvinyl chloride tube. Such a tube having a reduced breaking strength is not a problem under normal use, but for example, the tube is broken by the tube being pulled or bitten by the patient after surgery, and the outer surface of the tube is damaged. There is a risk that the tube will be broken or torn. In addition, when the tube breaks during the infusion, a phenomenon such as the drug not being administered to the patient or the blood of the patient flowing back into the tube may occur, resulting in a health hazard. Under such circumstances, there is a demand for a tube that has high breaking strength and does not break during use.

  Moreover, in the tube formed from the raw material disclosed in Patent Document 2 or 3, there are also those excellent in breaking strength, but the kink resistance is inferior compared to a conventional soft polyvinyl chloride tube, Low compatibility with infusion pumps.

  The infusion pump secures safety by detecting the pressure of a tube connected to the infusion pump and stopping the infusion for abnormal values. Conventionally, the upper and lower pressure limits have been set based on polyvinyl chloride resin. However, if the tube is too flexible, the detection sensitivity will be unnecessarily high. Conversely, if the tube is too hard, the detection mechanism will detect it. And safety cannot be ensured. Since an infusion pump is usually used at 5 to 40 ° C., it is required to have appropriate flexibility and kink resistance in this temperature range.

  Generally, when the breaking strength of the tube material is increased, the Young's modulus increases, and the safety mechanism of the infusion pump does not work properly. Moreover, kink resistance will also fall.

  Accordingly, the present invention is formed from a non-halogen material that is difficult to adsorb drugs, and has a breaking strength close to that of a soft polyvinyl chloride tube, and is compatible with an infusion pump, that is, has good kink resistance. An object is to provide a medical tube.

  As a result of accumulating diligent research in view of the above situation, the present inventors have found that when a diene polymer is used for the inner layer, absorption of a drug such as nitroglycerin can be suppressed, and the tube has a three-layer structure. When the tube has a two-layer structure for the intermediate layer, it was found that the tensile strength at break is improved when an olefin polymer is used for the inner layer. Furthermore, by controlling the ratio of the cross-sectional area of each layer to the total cross-sectional area of the tube, it was found that the tube can have kink resistance suitable for the pressure detection mechanism of the infusion pump, and the present invention has been completed.

  That is, the present invention is a medical tube comprising a first layer formed from an olefin polymer and a second layer formed outside the first layer and formed from a diene polymer. A medical tube in which the ratio of the cross-sectional area of one layer is 5 to 30% with respect to the total cross-sectional area of the tube, and the ratio of the cross-sectional area of the second layer is 70 to 95% with respect to the total cross-sectional area of the tube. provide.

  According to the present invention, a non-halogen-based material that hardly absorbs a drug, has a breaking strength close to that of a soft polyvinyl chloride tube, and is compatible with an infusion pump, that is, has good kink resistance. A formed medical tube can be provided

  Hereinafter, the present invention will be described in detail.

(First embodiment)
As shown in FIG. 1, the first embodiment of the present invention comprises a first layer formed from an olefin polymer and a second layer formed from a diene polymer provided outside the first layer. The ratio of the cross-sectional area of the first layer is 5-30% with respect to the total cross-sectional area of the tube, and the ratio of the cross-sectional area of the second layer is 70 with respect to the total cross-sectional area of the tube. It is a medical tube which is -95%.

  The olefin polymer used in this embodiment is an α-olefin homopolymer, a random copolymer, a block copolymer and a mixture thereof, or a random copolymer of an α-olefin and another unsaturated monomer. Polymers, block copolymers, graft copolymers, and those obtained by oxidizing or sulfonating these polymers can be used alone or in combination of two or more. Specifically, polyethylene, ethylene such as high density polyethylene (HDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), very ultra low density polyethylene (ULDPE), linear low density polyethylene (LLDPE), etc. -Propylene copolymer, ethylene-nonconjugated diene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-acetic acid Ethylene copolymers such as vinyl copolymer, ethylene-vinyl alcohol copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-ethyl (meth) acrylate copolymer, homopolypropylene, random polypropylene, block polypropylene Polypropylene such as Coalescence, polycyclopentene, polymers of cyclic olefins, such as poly-cyclohexene, polybutene, polyisobutylene, polymethylpentene and the like. Among these, polyethylene, an ethylene-based copolymer, a polypropylene-based polymer, or a mixture thereof can be preferably used from the viewpoint of cost and physical property balance. Among these, low density polyethylene, ultra-low density polyethylene, linear low density polyethylene, polybutene and the like are more preferable, and low density polyethylene and linear low density polyethylene are more preferable. In particular, linear low-density polyethylene is most preferable in consideration of the tensile strength at break when the medical tube of the present invention is used, Young's modulus, heat fusion property with a polypropylene connector, and laser fusion property.

  The production method of the olefin polymer is not particularly limited, and a conventionally known method can be appropriately selected and employed. For example, an olefin polymer can be produced by coordination polymerization, radical polymerization, anion polymerization, or the like using a Ziegler-Natta catalyst or a metallocene catalyst.

  Although there is no restriction | limiting in particular about the molecular weight of the said olefin polymer, It is preferable that a weight average molecular weight is 10,000-400,000 from a viewpoint of the moldability and intensity | strength when it is set as the medical tube of this invention. The weight average molecular weight is a polystyrene equivalent value measured by GPC method.

  In order to obtain the above characteristics, the olefin polymer may be blended with process oil or the like as long as the drug is not absorbed during infusion. Although it does not specifically limit as process oil used by this invention, Usually, a liquid or liquid material is used suitably at room temperature, such as 25 degreeC. Specific examples include process oils for rubbers or resins such as mineral oils, vegetable oils, animals, and synthetics. Mineral oils include naphthenic mineral oils, paraffinic mineral oils such as liquid paraffin, and vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, and wax Pine oil, olive oil and the like, squalene and the like as animal systems, and polybutene and low molecular weight polybutadiene as examples of synthetic systems. Among these, liquid paraffin and squalene are preferably used from the viewpoint of compatibility and physical property balance. These can be used in combination of two or more kinds in order to obtain desired physical properties.

  The diene polymer used in the present embodiment includes a polymer, copolymer, or hydrogenated product thereof containing a C 4-18 diene monomer as a structural unit.

  Examples of the diene monomer include 1,3-butadiene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene, 1,3-pentadiene, 1,3- Hexadiene, 1,3-heptadiene, cyclopentadiene, dicyclopentadiene, ethylidene norbornene and the like can be mentioned, and these can be used alone or in combination of two or more.

  The diene polymer may contain other polymerizable monomer as a constituent unit together with the diene monomer.

  Examples of the other polymerizable monomer include aromatic vinyl compounds having 8 to 20 carbon atoms such as styrene and α-methylstyrene, olefins having 2 to 8 carbon atoms such as ethylene and propylene, and carbon such as acrylonitrile. Unsaturated nitriles having 3 to 20 carbon atoms, (meth) acrylic acid esters having 4 to 20 carbon atoms such as methyl (meth) acrylate and ethyl (meth) acrylate, and unsaturated carbon atoms having 4 to 20 carbon atoms such as maleic anhydride Polycarboxylic acid anhydride, methyl vinyl ketone, ethyl vinyl ketone, vinyl acetate, (meth) acrylamide, glycidyl (meth) acrylate, etc. can be mentioned, and these can be used alone or in admixture of two or more. .

  The production method of the diene polymer is not particularly limited, and a conventionally known method can be appropriately selected and employed. For example, the diene monomer is optionally combined with other polymerizable monomers, radical polymerization initiators such as hydrogen peroxide, benzoyl peroxide, azobisisobutyronitrile, or n-butyllithium, By polymerizing at −100 to 150 ° C., more preferably at −10 to 130 ° C., using a solvent as necessary in the presence of an anionic polymerization initiator such as sec-butyl lithium, sodium naphthalene, metallic sodium and the like. A diene polymer can be produced.

  In the case of a diene polymer having a structural unit derived from two or more types of monomers, the bonding form is not particularly limited, and may be any of random, tapered, block, or a combination of two or more of these. Good. In the case of a block copolymer, the bonding mode is not particularly limited, and may be any of a diblock type, a triblock type, a multiblock type, and the like.

  Furthermore, as the diene polymer, a hydrogenated product obtained by hydrogenating part or all of the double bonds remaining in the diene polymer can be used. For this hydrogenation, a known hydrogenation catalyst and hydrogenation method can be used. For example, a hydrogenation catalyst and a hydrogenation method as described in JP-A-5-222115 can be employed.

  Specific examples of the diene polymer having the above structure include polybutadiene such as 1,4-polybutadiene and 1,2-polybutadiene, hydrogen such as hydrogenated 1,4-polybutadiene and hydrogenated 1,2-polybutadiene. Added polybutadiene, polyisoprene, hydrogenated polyisoprene, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene -Styrene block copolymer (SEBS), styrene-isoprene block copolymer, hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene- Styrene Copolymer (SEPS), styrene-butadiene random copolymer (SBR), hydrogenated styrene-butadiene random copolymer, styrene-isoprene random copolymer (SIR), hydrogenated styrene-isoprene random copolymer These may be used alone or in combination of two or more. Among the aforementioned diene polymers, 1,4-polybutadiene, polybutadiene such as 1,2-polybutadiene, polyisoprene, styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer. Polymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS) are preferable, and 1,4-polybutadiene and 1,2-polybutadiene are more preferable. . In particular, 1,2-polybutadiene is most preferable in view of kink resistance and flexibility when the medical tube of the present invention is used.

  Although there is no restriction | limiting in particular about the molecular weight of the said diene polymer, It is preferable that a weight average molecular weight is 10,000-100,000. The weight average molecular weight is a polystyrene equivalent value measured by GPC method.

  The olefin polymer and the diene polymer are antioxidants, ultraviolet absorbers, as long as they do not impair the properties such as tensile break strength, kink resistance, and transparency when used as the medical tube of the present invention. Various additives such as lubricants, or other resins can be included. Specifically, antioxidants, heat stabilizers, light stabilizers, UV absorbers, neutralizers, lubricants, antifogging agents, slip agents, crosslinking agents, crosslinking aids, dyes, pigments, flame retardants, dispersants Various additives such as antistatic agents and antiblocking agents, inorganic fillers such as calcium carbonate, silica, talc and mica, resins such as styrene block copolymers, polyacrylic acid and polyacrylic acid esters. it can. The amount of the various additives or inorganic filler added is preferably 0.001 to 5 mass%, more preferably 0.01 to 3 mass% when the olefin polymer or the diene polymer is 100 mass%. % By mass.

  The medical tube according to the present invention is characterized in that the cross-sectional area of the first layer and the second layer is a specific ratio with respect to the total cross-sectional area of the tube.

  The ratio of the cross-sectional area of the first layer is 5 to 30% with respect to the total cross-sectional area of the tube, and is preferably 5 to 20% from the viewpoint of kink resistance, flexibility, strength, etc. of the tube, More preferably, it is 5 to 15%. If the ratio of the cross-sectional area of the first layer is less than 5%, the breaking strength of the tube decreases, and if it exceeds 30%, the kink resistance of the tube decreases, which is not preferable.

  The ratio of the cross-sectional area of the second layer is 70 to 95% with respect to the total cross-sectional area of the tube, and is preferably 80 to 95% from the viewpoint of kink resistance, flexibility, strength, etc. of the tube, 85 More preferably, it is -95%. If the ratio of the cross-sectional area of the second layer is less than 70%, the Young's modulus of the tube increases, and if it exceeds 95%, the tensile strength at break of the tube decreases, which is not preferable.

  The ratio of the cross-sectional area of each layer in this embodiment is calculated by the following mathematical formulas 1-2.

  In order for the medical tube of this embodiment to have excellent tensile breaking strength and kink resistance, the tensile breaking strength at 25 ° C. of the olefin polymer is preferably 20 to 50 MPa, more preferably 30 to 50 MPa. And the Young's modulus at 25 ° C. is preferably 10 to 50 MPa, more preferably 10 to 45 MPa. When the tensile breaking strength of the olefin polymer is less than 20 MPa, the tensile breaking strength of the medical tube of the present invention may be reduced, and when it exceeds 50 MPa, the Young's modulus of the medical tube of the present invention is increased. There is a case. Further, if the Young's modulus of the olefin polymer is less than 10 MPa, the kink resistance of the medical tube of the present invention may be reduced, and if it exceeds 50 MPa, the compatibility with an infusion pump may be reduced. is there.

  Furthermore, in order for the medical tube of this embodiment to have excellent tensile breaking strength and kink resistance, the tensile breaking strength at 25 ° C. of the diene polymer is preferably 10 to 30 MPa, more preferably 12 The Young's modulus at 25 ° C. is preferably 3 to 20 MPa, and more preferably 5 to 15 MPa. If the tensile breaking strength of the diene polymer is less than 10 MPa, the tensile breaking strength of the medical tube of the present invention may decrease. If it exceeds 30 MPa, the Young's modulus also increases and the suitability for an infusion pump decreases. There is a case. In addition, if the Young's modulus is less than 3 MPa, it may be too soft, and the compatibility with the infusion pump and the scratch resistance of the tube surface may be reduced. Compatibility with the pump may be reduced. In particular, considering the kink resistance of the medical tube of the present invention, the Young's modulus at 25 ° C. of the diene polymer is more preferably smaller than the Young's modulus at 25 ° C. of the olefin polymer. .

  If the tensile break strength and Young's modulus of the olefin polymer and the diene polymer are in the above ranges, kink resistance that can appropriately cope with pressure detection of an infusion pump can be ensured.

(Second embodiment)
As shown in FIG. 2, the second embodiment of the present invention further includes a third layer formed of a diene polymer provided inside the first layer, and the first layer with respect to the total cross-sectional area of the tube. The ratio of the sectional area of the layer is 5 to 30%, the ratio of the sectional area of the second layer to the total sectional area of the tube is 50 to 92%, and the sectional area of the third layer to the total sectional area of the tube It is a medical tube whose ratio is 3 to 20%.

  The ratio of the cross-sectional area of the first layer is 5 to 30% with respect to the total cross-sectional area of the tube, and considering the kink resistance of the tube, it is preferably 5 to 20%, and preferably 5 to 15%. It is more preferable. If the ratio of the cross-sectional area of the first layer is less than 5%, the tensile strength at break of the tube is lowered, and if it exceeds 30%, the kink resistance of the tube is lowered.

  The ratio of the cross-sectional area of the second layer is 50 to 92% with respect to the total cross-sectional area of the tube, and considering the kink resistance and flexibility of the tube, it is preferably 60 to 90%, and 70 to 90%. % Is more preferable.

  The ratio of the cross-sectional area of the third layer is 3 to 20% with respect to the total cross-sectional area of the tube, preferably 5 to 20%, and more preferably 5 to 15%. If the ratio of the cross-sectional area of the third layer is less than 3%, delamination of the tube may occur, and if it exceeds 20%, the kink resistance of the tube decreases, which is not preferable.

  The ratio of the cross-sectional areas of the respective layers is calculated by the following mathematical formulas 3 to 5.

  The medical tube of the present invention can be molded according to a known molding method such as extrusion molding, injection molding, blow molding, and rotational molding. There are no restrictions on the inner diameter, outer diameter, length, etc. of the medical tube, and it may be appropriately selected according to the application. In addition, the outer diameter of a general medical tube is 1-10 mm, and an internal diameter is 0.5-7 mm.

  In addition, the medical tube of the present invention has a tensile strength at 25 ° C. of preferably 60 N or more, more preferably 60 to 100 N, and a Young's modulus at 5 to 40 ° C. is preferably 3 to 20 MPa, more preferably 5 ~ 15 MPa. If the tensile strength at break is less than 60 N, the tube breaks due to the tube being pulled or bitten by the patient after surgery, and further, the tube breaks or breaks due to the outer surface of the tube being damaged. There is. If the Young's modulus exceeds 20 MPa, the tube may become hard and may not be compatible with a commercially available infusion pump pressure sensor. If the Young's modulus is less than 3 MPa, the tube is too soft and excessive when used in an infusion pump. In some cases, the pressure increases and the actual use is difficult due to the sensitivity to the detection mechanism of the infusion pump.

  Furthermore, the kink resistance of the medical tube of the present invention is preferably equal to or higher than that of a polybutadiene tube. Specifically, as shown in FIG. 3, both ends of a tube cut to a length of 120 mm are fixed, compressed at a speed of 20 mm / min using a tensile tester, and the kink calculated by the following formula 6 The distance is preferably 15 mm or less, and more preferably 14 mm or less. If the kink distance is 15 mm or less, it means that the medical tube of the present invention has kink resistance close to that of a conventional polybutadiene tube.

  In addition, it is preferable that the medical tube of the present invention is substantially transparent so that liquids and bubbles moving in the tube can be confirmed. Here, the phrase “substantially transparent” means that the liquid in the tube or the level of transparency that allows the bubbles mixed in the liquid to be visually recognized. Specifically, the total light transmittance of the tube measured by JIS standard K7105 “Testing method for optical properties of plastic” is preferably 75 to 100%, more preferably 80 to 100%.

  The medical tube of the present invention includes a catheter tube for drug administration, an infusion tube, in particular an infusion pump tube, an extension tube, a blood circuit tube, a winged vein needle tube, etc. in addition to the use of a conventional polyvinyl chloride tube Can be suitably used.

  EXAMPLES Next, although an Example is given and this invention is demonstrated concretely, these Examples do not restrict | limit this invention at all.

  The olefin polymers and diene polymers used in Examples and Comparative Examples are shown in Table 1 below.

Example 1
RB810, which is 1,2-polybutadiene, is used as the olefin polymer for the first layer, linear low density polyethylene (Nipolon Z1P53A: manufactured by Tosoh Corporation) as the diene polymer for the second and third layers. Using a blend of 70 parts by weight (manufactured by JSR Corporation) and 30 parts by weight of RB820 (manufactured by JSR Corporation), the thickness of the third layer is 50 μm and the thickness of the first layer is 110 μm using a three-layer extruder. A three-layer tube having a second layer thickness of 460 μm, an inner diameter of 2.08 mm, and an outer diameter of 3.32 mm was produced.

(Examples 2 to 4)
The olefin polymer shown in Table 2 below was used as the first layer, except that the thicknesses of the first layer, the second layer, and the third layer, and the outer diameter and inner diameter of the tube were as shown in Table 2. A three-layer tube was produced in the same manner as in Example 1.

(Example 5)
As the olefin polymer for the first layer, linear low density polyethylene (Nipolon Z1P53A: manufactured by Tosoh Corporation) is used, and as the diene polymer for the second layer, RB810 (JSR Corporation, which is 1,2-polybutadiene). Made by blending 70 parts by weight and 30 parts by weight of RB820 (manufactured by JSR Corporation), using a two-layer extruder, the inner layer has a thickness of 50 μm, the outer layer has a thickness of 595 μm, and the inner diameter is 2.08 mm. A two-layer tube having an outer diameter of 3.37 mm was produced.

(Comparative Example 1)
Using a blend of 70 parts by weight of RB810 (manufactured by JSR Corporation) and 30 parts by weight of RB820 (manufactured by JSR Corporation) used in the second layer and the third layer of Example 1, an inner diameter of 2.10 mm, outside A single-layer tube having a diameter of 3.40 mm was produced.

(Comparative Examples 2 to 4)
The thermoplastic polyolefin shown in Table 2 below was used as the first layer, and the thicknesses of the first layer, the second layer, and the third layer, and the outer diameter and inner diameter of the tube were changed as shown in Table 2. A three-layer tube was prepared in the same manner as in Example 1.

(Comparative Example 5)
A tube was produced in the same manner as in Example 5 except that the thicknesses of the first layer and the second layer were as shown in Table 2 below.

(Evaluation)
Using the tubes obtained in Examples 1 to 5 and Comparative Examples 1 to 5, the tensile breaking strength, tensile breaking elongation, Young's modulus, kink resistance, and pressure detection of the infusion pump were evaluated according to the following. The results are shown in Table 3.

(1) Measurement of tensile breaking strength and tensile breaking elongation Using a tensile testing machine (manufactured by Shimadzu Corporation, Autograph AG-IS) at 25 ° C. under conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm / min. Tensile rupture strength and tensile rupture elongation were measured.

(2) Measurement of Young's Modulus Using the same tensile tester as in (1) above, Young's modulus was measured at 25 ° C. under conditions of a distance between chucks of 50 mm and a tensile speed of 50 mm / min.

(3) Measurement of kink resistance Both ends of a tube cut to a length of 120 mm are fixed as shown in FIG. 2 and compressed at a speed of 20 mm / min using the same tensile tester as in (1) above, resulting in kink. The distance was measured. The kink distance was calculated according to the following formula 6, and the case where the kink distance was 15 mm or less was regarded as good.

(4) Measurement of pressure detection of infusion pump A tube filled with water was installed in an infusion pump (Terumo Corporation, TE-131), and a pressure gauge was connected to the discharge-side tip of the tube. The pump was operated at a flow rate of 100 ml / min, and the pressure when the pump was stopped by a clogging alarm was measured to confirm whether it was within the standard value (30 to 140 kPa).

(result)
It turned out that the medical tube of this invention shown in Examples 1-5 is excellent in tensile breaking strength and kink resistance compared with the tube of a comparative example. In addition, it showed good sensitivity for detecting the pressure of an infusion pump and was found to be suitable for medical use.

  The medical tube of the present invention can be suitably used for medical applications such as an infusion tube.

It is sectional drawing which shows the medical tube by 1st Embodiment of this invention. It is sectional drawing which shows the medical tube by 2nd Embodiment of this invention. It is the schematic which showed the measuring method of kink resistance.

Explanation of symbols

1 first layer,
2 Second layer,
3 Third layer.

Claims (7)

A medical tube comprising a first layer formed from polyethylene and a second layer formed outside the first layer and formed from a diene polymer,
The ratio of the cross-sectional area of the first layer is 5 to 30% with respect to the total cross-sectional area of the tube,
The ratio of the cross-sectional area of the second layer is 70 to 95% with respect to the total cross-sectional area of the tube,
The tensile breaking strength at 25 ° C. is 60 N or more, and the Young's modulus at 5 to 40 ° C. is 3 to 20 MPa.
Medical tube. A third layer formed from a diene polymer provided inside the first layer;
The ratio of the cross-sectional area of the first layer to the total cross-sectional area of the tube is 5-30%,
The ratio of the cross-sectional area of the second layer to the total cross-sectional area of the tube is 50 to 92%,
The ratio of the cross-sectional area of the third layer to the total cross-sectional area of the tube is 3 to 20%.
The medical tube according to claim 1. The medical tube according to claim 1 or 2, wherein the polyethylene has a tensile breaking strength at 25 ° C of 20 to 50 MPa and a Young's modulus at 25 ° C of 10 to 50 MPa.   The diene polymer has a tensile breaking strength at 25 ° C. of 10 to 30 MPa, the Young's modulus at 25 ° C. is 3 to 20 MPa, and the Young's modulus of the diene polymer at 25 ° C. The medical tube according to any one of claims 1 to 3, which has a value smaller than the Young's modulus at 25 ° C of the polymer. The medical tube according to any one of claims 1 to 4 , wherein the polyethylene is linear low-density polyethylene. The medical tube according to any one of claims 1 to 5 , wherein the diene polymer is 1,4-polybutadiene or 1,2-polybutadiene. The medical tube according to claim 6 , wherein the diene polymer is 1,2-polybutadiene.

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