Easy-to-peel pipe, and preparation method therefor

Abstract

An easy-to-peel pipe and a preparation method therefor. The pipe uses an ethylene-acrylate copolymer as a matrix resin. Since ethylene-acrylate is a copolymer and contains an acrylate side group, the crystallization thereof is disorganized, the distance between main chain vinyl molecules is increased, and the structure of molecular entanglement is reduced, thereby reducing the cohesive strength of an ethylene-acrylate molecular chain. The orientation degree of the molecular chain inside the ethylene-acrylate copolymer is further controlled by means of an extrusion process, ensuring that the orientation degree is in the range of 23-95%, such that the molecular chain and the chain segment of the ethylene-acrylate copolymer stretch in the orientation direction from the disordered state of free curling, thereby further reducing the structure of molecular entanglement and achieving the tearability of the pipe.

Description

Easy-to-peel pipe and preparation method thereof

[0001] Cross-references

[0002] This application claims priority to the Chinese invention patent application with application number 2023118500542 filed on December 29, 2023, entitled “A kind of easy-to-peel pipe and its preparation method”, the contents of which are incorporated herein by reference.

[0003] This application claims priority to the Chinese invention patent application with application number 2023118393447 filed on December 29, 2023, entitled “A kind of easy-to-peel pipe”, the contents of which are incorporated herein by reference. Technical Field

[0004] The present application relates to the technical field of pipes, and in particular to an easily peelable pipe and a preparation method thereof. Background Art

[0005] Easy-to-peel tubes can be used as protective tubes for precision instruments, electronic components, etc., catheter hoses, medical device introduction tubes for introducing guide wires into the body, assembly fixtures for catheter hoses, etc., and when no longer needed, the tubes can be removed by peeling.

[0006] Currently, the main material for easy-peel tubing on the market is PTFE. This product is expensive and primarily manufactured overseas, with complex production processes and high technical barriers. However, with the rapid development of healthcare, the demand for easy-peel tubing is increasing, and the long procurement cycle overseas has significantly impacted the development of domestic healthcare. Our company has independently developed an easy-peel tubing made of polyolefin and its copolymer resin. This has a lower tear strength than PTFE and does not bond to internal materials, making it a perfect alternative to PTFE, providing a new alternative for easy-peel tubing. Summary of the Invention

[0007] The main purpose of the present application is to provide an easily peelable tube made of polyolefin and its copolymer resin, which has a lower tear strength than the PTFE tearable tube and does not have adhesion to the internal material.

[0008] In a first aspect, an embodiment of the present application provides an easily peelable tube having linear tearing properties in the longitudinal direction of the tube. The material for preparing the easily peelable tube comprises ethylene-acrylate copolymer as a matrix resin, and the extrusion process controls the molecular chain orientation of the extruded tube to be 23%-95%.

[0009] In some embodiments of the present application, the molecular chain orientation degree of the extruded pipe is 30%-90%.

[0010] In some embodiments of the present application, the ethylene-acrylate copolymer includes at least one of ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methyl methacrylate copolymer (EMMA).

[0011] In some embodiments of the present application, the ethylene-acrylate copolymer has a melt index of (0.5-10) g / 10 min and an acrylic acid content of 9 wt%-30 wt%.

[0012] In some embodiments of the present application, the ethylene-acrylate copolymer has a tear strength lower than 75 kN / m.

[0013] In some embodiments of the present application, the ethylene-acrylate copolymer has a tensile strength of 15-24 MPa.

[0014] In some embodiments of the present application, the easily peelable tube preparation material includes the following components, calculated by weight:

[0015] Ethylene-acrylate copolymer: 20-90 parts;

[0016] Enhancer: 10-80 parts.

[0017] In some embodiments of the present application, the reinforcing agent includes at least one of polyethylene, polyolefin elastomer, and ethylene-vinyl acetate copolymer.

[0018] In some embodiments of the present application, the polyethylene (PE) is low-density polyethylene (LDPE), and the low-density polyethylene (LDPE) has a melt index of (0.3-7) g / 10 min and a tensile strength of 17-30 MPa.

[0019] In some embodiments of the present application, the polyethylene (PE) is a linear low-density polyethylene (LLDPE), and the linear low-density polyethylene (LLDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 20-35 MPa.

[0020] In some embodiments of the present application, the polyethylene (PE) is medium-density polyethylene (MDPE), and the medium-density polyethylene (MDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 25-35 MPa.

[0021] In some embodiments of the present application, the polyethylene (PE) is high-density polyethylene (HDPE), and the high-density polyethylene (HDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 28-40 MPa.

[0022] In some embodiments of the present application, the polyolefin elastomer (POE) has a melt index of (0.5-5) g / 10 min, a tensile strength of 18-40 MPa, and a melting temperature of 70-110°C.

[0023] In some embodiments of the present application, the ethylene-vinyl acetate copolymer (EVA) has a melt index of (0.5-7) g / 10 min, a tensile strength of 16-25 MPa, and a vinyl acetate (VA) content of no more than 20%.

[0024] In some embodiments of the present application, the easily peelable tube preparation material further comprises at least one of the following additives, calculated by weight:

[0025] Antioxidant 0.05-0.3 parts;

[0026] Lubricant 0.05-0.1 parts;

[0027] Wherein, the antioxidant includes but is not limited to asymmetric hindered phenol antioxidants, aromatic amine antioxidants, thioether antioxidants, and phosphite antioxidants;

[0028] The lubricant includes but is not limited to PTFE powder, zinc stearate, magnesium stearate, silicone, calcium stearate or ethylene bisstearamide.

[0029] In some embodiments of the present application, the ratio representing the tear linearity is in the range of 50%:50% to 48%:52%.

[0030] In some embodiments of the present application, the inner diameter of the easily peelable tube is 0.3-16 mm.

[0031] In some embodiments of the present application, the wall thickness of the easily peelable tube is 0.1-2 mm.

[0032] In a second aspect, an embodiment of the present application provides an easily peelable tube having linear tearing properties in the length direction of the tube. The material for preparing the easily peelable tube comprises ethylene-acrylate copolymer as a matrix resin, and the molecular chain orientation degree of the easily peelable tube is 23%-95%.

[0033] In some embodiments of the present application, the molecular chain orientation degree of the easily peelable tube is 30%-95%.

[0034] In some embodiments of the present application, the molecular chain orientation degree of the easily peelable tube is 30%-90%.

[0035] In some embodiments of the present application, the molecular chain orientation degree of the easily peelable tube is 35%-90%.

[0036] In a third aspect, an embodiment of the present application provides a method for preparing an easily peelable tube, comprising the following steps:

[0037] Masterbatch processing: the raw materials are mixed evenly, extruded through an extrusion device, stretched into strips, and pelletized to obtain masterbatch particles, wherein the raw materials include ethylene-acrylate copolymer;

[0038] Extrusion into tubes: The masterbatch particles obtained above are extruded into tubes through an extruder to obtain the easily peelable tubes, wherein the orientation degree of the molecular chains of the extruded tubes is controlled to be 23%-95%.

[0039] In some embodiments of the present application, in the masterbatch processing step, the raw material further includes at least one of a reinforcing agent, an antioxidant, and a lubricant.

[0040] In some embodiments of the present application, in the masterbatch processing step, the mixing time is 3-5 minutes.

[0041] In some embodiments of the present application, in the masterbatch processing step, the extrusion temperature of the extrusion equipment is 130-200°C.

[0042] In some embodiments of the present application, in the extrusion tube forming step, the orientation degree of the molecular chains of the extruded tube is 30%-90%.

[0043] In some embodiments of the present application, the ethylene-acrylate copolymer includes at least one of ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methyl methacrylate copolymer (EMMA).

[0044] In some embodiments of the present application, the ethylene-acrylate copolymer has a melt index of (0.5-10) g / 10 min and an acrylic acid content of 9 wt%-30 wt%.

[0045] In some embodiments of the present application, the ethylene-acrylate copolymer has a tear strength lower than 75 kN / m.

[0046] In some embodiments of the present application, the ethylene-acrylate copolymer has a tensile strength of 15-24 MPa.

[0047] In some embodiments of the present application, the easily peelable tube preparation material includes the following components, calculated by weight:

[0048] Ethylene-acrylate copolymer: 20-90 parts;

[0049] Enhancer: 10-80 parts.

[0050] In some embodiments of the present application, the reinforcing agent includes at least one of polyethylene, polyolefin elastomer, and ethylene-vinyl acetate copolymer.

[0051] In some embodiments of the present application, the polyethylene (PE) is low-density polyethylene (LDPE), and the low-density polyethylene (LDPE) has a melt index of (0.3-7) g / 10 min and a tensile strength of 17-30 MPa.

[0052] In some embodiments of the present application, the polyethylene (PE) is a linear low-density polyethylene (LLDPE), and the linear low-density polyethylene (LLDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 20-35 MPa.

[0053] In some embodiments of the present application, the polyethylene (PE) is medium-density polyethylene (MDPE), and the medium-density polyethylene (MDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 25-35 MPa.

[0054] In some embodiments of the present application, the polyethylene (PE) is high-density polyethylene (HDPE), and the high-density polyethylene (HDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 28-40 MPa.

[0055] In some embodiments of the present application, the polyolefin elastomer (POE) has a melt index of (0.5-5) g / 10 min, a tensile strength of 18-40 MPa, and a melting temperature of 70-110°C.

[0056] In some embodiments of the present application, the ethylene-vinyl acetate copolymer (EVA) has a melt index of (0.5-7) g / 10 min, a tensile strength of 16-25 MPa, and a vinyl acetate (VA) content of no more than 20%.

[0057] In some embodiments of the present application, the easily peelable tube preparation material further comprises at least one of the following additives, calculated by weight:

[0058] Antioxidant 0.05-0.3 parts;

[0059] Lubricant 0.05-0.1 parts;

[0060] The antioxidant comprises at least one of an asymmetric hindered phenol antioxidant, an aromatic amine antioxidant, a thioether antioxidant, and a phosphite antioxidant;

[0061] The lubricant includes at least one of PTFE powder, zinc stearate, magnesium stearate, silicone, calcium stearate or ethylene bisstearamide.

[0062] Beneficial effects that this application can achieve:

[0063] The easy-to-peel pipe provided in the present application adopts ethylene-acrylate copolymer as the base resin. Since ethylene-acrylate is a copolymer and contains acrylate side groups, its crystallization is disrupted, the distance between the main chain vinyl molecules is increased, and the entanglement structure of the molecules is reduced, so that the cohesive strength of the ethylene-acrylate molecular chain decreases. The orientation degree of the internal molecular chain of the ethylene-acrylate copolymer is further controlled through the extrusion process to ensure that the orientation degree is in the range of 23%-95%, so that the ethylene-acrylate copolymer molecular chains and chain segments stretch from the freely curled disordered state to the orientation direction, further reducing the entanglement structure of the molecules and realizing the tearability of the pipe. DETAILED DESCRIPTION

[0064] It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0065] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0066] In this application, the descriptions of "first", "second", etc. are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0067] An oriented polymer structure refers to a structure in which, under the influence of an external force, molecular chains or other structural units are preferentially aligned and frozen in the direction of the force. During the extrusion and stretching process of melt-extruded ethylene-acrylate copolymer, the molecular chains of the ethylene-acrylate copolymer align along the stretching direction, i.e., they are preferentially oriented in the stretching direction.

[0068] Ethylene-acrylate copolymers are copolymerized with ethylene and acrylate, and mainly include ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methyl methacrylate copolymer (EMMA). The properties of ethylene-acrylate copolymers are related to the content of acrylate monomers, average molecular weight, molecular weight distribution, and long and short chain branches.

[0069] Polymer materials exist as entangled chains of molecules, like a tangled yarn. This molecular entanglement persists even in molded articles made from these materials, and the physical properties of the molded articles significantly influence the structure of this molecular entanglement. While researching peelable tubing, we unexpectedly discovered that using ethylene-acrylate copolymer as a base resin ensures that the molecular chain orientation of the extruded tubing during the extrusion process is within a range of 23%-95%, resulting in an easily peelable tubing with linear tear resistance along its length. The degree of orientation of the extruded tubing during the extrusion process refers to the degree of orientation of the finished easily peelable tubing. This may be due to the particularity of the structure of materials such as ethylene-acrylate copolymers, which contain methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate side groups, which affect the crystallization and molecular entanglement of the molecules, increase the distance between the main chain molecules, and reduce the molecular entanglement structure, resulting in a decrease in the cohesive strength of the ethylene-acrylate copolymer molecular chain. The orientation degree of the internal molecular chains of the ethylene-acrylate copolymer is further controlled through the extrusion process to ensure that the orientation degree is in the range of 23%-95%, so that the ethylene-acrylate copolymer molecular chains and chain segments stretch from the freely curled disordered state to the orientation direction, further reducing the molecular entanglement structure and achieving the tearability of the pipe. The ordered change in orientation significantly improves the strength of the copolymer along the length of the pipe, while the strength in the direction perpendicular to the pipe decreases, which further improves the strength and tearability of the pipe.

[0070] In the extrusion process, the stretching ratio is ensured by adjusting the difference between the extrusion speed of the tube billet from the die and the pulling speed of the tube by the pulling machine. By controlling the stretching ratio of the extruded tube between 5-60, preferably between 7-30, an extruded tube with a molecular chain orientation degree of 23%-95% is obtained.

[0071] Increasing the acrylate monomer content in ethylene-acrylate copolymers further reduces the order of the molecular chain and increases the content of acrylic acid side groups, resulting in decreased crystallinity and a lower melting point, which improves tearability. However, excessively high acrylate monomer content can reduce cohesive strength, resulting in reduced overall pipe strength and other issues, hindering pipe molding and performance. Therefore, an acrylic acid content of 9wt% to 30wt% is ideal.

[0072] Melt index (MI) is an indicator of resin fluidity. The melt index is the mass of the resin melt passing through a standard capillary tube for 10 minutes at a certain temperature and pressure, and its unit is g / 10 minutes. A high melt index indicates a low average molecular weight of the resin, low viscosity, good fluidity, and easy processing and molding, but poor mechanical properties; a low melt index indicates a high average molecular weight of the resin, high viscosity, poor fluidity, and greater difficulty in molding, but good mechanical properties. In some embodiments, the melt index (MI) of the ethylene-acrylate copolymer is (0.5-6) ​​g / 10min. A melt index within this range can meet good fluidity and good mechanical properties.

[0073] In some embodiments, the ethylene-acrylate copolymer has a tear strength lower than 75 kN / m. Tear strength within this range facilitates better tearing of the tube.

[0074] In some embodiments, the ethylene-acrylate copolymer has a tensile strength of 15-24 MPa. A tensile strength within this range can improve the tensile strength of the pipe.

[0075] In order to further improve the tensile strength of the easily peelable tube, we can add polymers such as polyethylene (PE), polyolefin elastomer (POE), ethylene-vinyl acetate copolymer (EVA) as reinforcing agents. Polyethylene is a thermoplastic formed by the polymerization of ethylene. Due to the different densities of the resins obtained by different polymerization methods, they are divided into high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), and low-density polyethylene (LDPE). Polyolefin elastomer (POE) can be one of the random copolymer elastomers of ethylene and 1-butene, ethylene and 1-hexene, ethylene and 1-octene, etc.; when ethylene-vinyl acetate copolymer (EVA) is selected, the reinforcing effect is better when the content of vinyl acetate (VA) is less than 20%. In some embodiments, the easily peelable tube preparation material includes the following components, calculated by weight:

[0076] Ethylene-acrylate copolymer: 20-90 parts;

[0077] Enhancer: 10-80 parts.

[0078] The addition of the reinforcing agent can improve the tensile strength of the molecular structure, and further control the orientation of the internal molecular chains of the ethylene-acrylate copolymer and the reinforcing agent blend through the extrusion process to ensure that the orientation degree is in the range of 23%-95%, so that the molecular chains and chain segments of the ethylene-acrylate copolymer and the reinforcing agent blend stretch from a freely curled and disordered state to the orientation direction, reducing the linear entanglement structure of the blend molecules. Reinforcers have high crystallinity or long chain branches. Reinforcers with high crystallinity, such as PE or EVA, transform the crystals of the reinforcing agent from spherulites to monoclinic crystals during pipe extrusion stretching and orientation. The formation of monoclinic crystals not only improves the tensile strength in the orientation direction, but also increases the number of physical crosslinking points formed by the blend molecular chains and segments in the orientation direction (i.e., along the length of the pipe), thereby significantly improving the tensile strength in the orientation direction of the pipe. Reinforcers containing long chain branches, such as POE or LDPE, can form certain physical crosslinking points with the crystalline regions of the ethylene-acrylate copolymer. During extrusion stretching and orientation, the ethylene-acrylate copolymer is stretched from spherulites to monoclinic crystals, forming physical crosslinking points with the oriented long chain branches, improving the strength in the orientation direction, while the physical crosslinking points perpendicular to the orientation direction are significantly reduced, resulting in a decrease in the strength perpendicular to the orientation direction. By adding the appropriate proportion of reinforcing agent and controlling the degree of orientation during the extrusion stretching process, the reinforcing agent forms fiber-like reinforcing units along the orientation direction when the ethylene-acrylate copolymer is oriented, further improving the tearability of the pipe. Therefore, the addition of reinforcing agent can not only improve the tensile strength of the pipe in the orientation direction, but also further improve its tearability along the length direction of the pipe.

[0079] In some embodiments, the polyethylene (PE) is low-density polyethylene (LDPE), and the low-density polyethylene (LDPE) has a melt index of (0.3-7) g / 10 min and a tensile strength of 17-30 MPa.

[0080] In some embodiments, the polyethylene (PE) is linear low-density polyethylene (LLDPE), and the linear low-density polyethylene (LLDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 20-35 MPa.

[0081] In some embodiments, the polyethylene (PE) is medium-density polyethylene (MDPE), and the medium-density polyethylene (MDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 25-35 MPa.

[0082] In some embodiments, the polyethylene (PE) is high-density polyethylene (HDPE), and the high-density polyethylene (HDPE) has a melt index of (0.3-10) g / 10 min and a tensile strength of 28-40 MPa.

[0083] In some embodiments, the polyolefin elastomer (POE) has a melt index of (0.5-5) g / 10 min, a tensile strength of 18-40 MPa, and a melting temperature of 70-110°C.

[0084] In some embodiments, the ethylene-vinyl acetate copolymer (EVA) has a melt index of (0.5-7) g / 10 min, a tensile strength of 16-25 MPa, and a vinyl acetate (VA) content of no more than 20%.

[0085] Of course, to obtain a higher performance pipe, we can also add additives such as antioxidants and lubricants. In some embodiments, the easy-to-peel pipe preparation material also includes at least one of the following additives: 0.05-0.3 parts of antioxidant; 0.05-0.1 parts of lubricant.

[0086] The antioxidant is beneficial to improving the antioxidant performance and aging resistance of the easy-to-strip pipe and extending the service life of the easy-to-strip pipe. The antioxidant includes at least one of an asymmetric hindered phenol antioxidant, an aromatic amine antioxidant, a thioether antioxidant, and a phosphite antioxidant.

[0087] Among them, hindered phenol antioxidants include but are not limited to antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), BHT (2,6-di-tert-butyl-p-cresol), and antioxidant 1076 (n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

[0088] Among them, aromatic amine antioxidants include but are not limited to diphenylamine, p-phenylenediamine and dihydroquinoline and their derivatives or polymers, such as antioxidant 445 (4,4'-bis(α.α-dimethylbenzyl)diphenylamine).

[0089] Among them, thioether antioxidants include but are not limited to DLTP (dilauryl thiodipropionate), DSTDP (distearyl thiodipropionate), and DSTP (octadecyl thiodipropionate).

[0090] Among them, the phosphite antioxidant includes but is not limited to antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite), antioxidant 618 (pentaerythritol distearyl diphosphite), and antioxidant 626 (bis[2,4-di-tert-butylphenyl]pentaerythritol diphosphite).

[0091] The lubricant helps to promote more uniform mixing of various raw materials, including but not limited to PTFE powder, zinc stearate, magnesium stearate, silicone, calcium stearate or ethylene bisstearamide.

[0092] In some embodiments, the easily peelable tube preparation material includes the following components, calculated by weight:

[0093] Ethylene-acrylate copolymer: 20-90 parts, reinforcing agent: 10-80 parts. For example, the ethylene-acrylate copolymer can be any part by weight within the range of 20-90 parts, such as 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or 90 parts; the reinforcing agent can be any part by weight within the range of 10-80 parts, such as 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, or 80 parts.

[0094] Under the above weight limit, it is conducive to promoting the mixing of various raw materials, which can meet the linear tearing performance and achieve a certain tensile strength.

[0095] In some embodiments, the ratio representing the tear linearity ranges from 50%:50% to 48%:52%.

[0096] In some embodiments, the inner diameter of the easily peelable tube is 0.3-16 mm.

[0097] In some embodiments, the wall thickness of the easily peelable tube is 0.1-2 mm.

[0098] The present application also provides a method for preparing an easily peelable tube, comprising the following steps:

[0099] Masterbatch processing: the raw materials are mixed evenly, extruded through an extrusion device, stretched into strips, and pelletized to obtain masterbatch particles, wherein the raw materials include ethylene-acrylate copolymer;

[0100] Extrusion into tubes: The masterbatch particles obtained above are extruded into tubes through an extruder to obtain the easily peelable tubes, wherein the orientation degree of the molecular chains of the extruded tubes is controlled to be 23%-95%.

[0101] In some embodiments, during the masterbatch processing step, the raw material further comprises at least one of a reinforcing agent, an antioxidant, and a lubricant.

[0102] In some embodiments, in the masterbatch processing step, the mixing time is 3-5 minutes.

[0103] In some embodiments, in the masterbatch processing step, the extrusion temperature of the extrusion equipment is 130-200°C.

[0104] In some embodiments, during the extrusion step, the orientation degree of the molecular chains of the extruded tube is 30%-90%.

[0105] The technical solution of the present application is further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present application and are not used to limit the present application.

[0106] Determination of stretch ratio

[0107] A single-screw extruder is used, and the specifications of the extrusion die are as follows: the die is D1 (mm), the core rod is D2 (mm), and the dimensions of the extruded pipe are as follows: the inner diameter of the extruded pipe is d1 (mm) and the wall thickness is w (mm) (depending on the size of the extruded pipe, the corresponding model of extruder, die and core rod must be selected). During the extrusion process, we control the pulling speed and extrusion speed to obtain extruded pipes with different stretch ratios. The stretch ratio calculation formula is as follows:

[0108] Determination of orientation

[0109] The test was performed using synchrotron wide-angle X-ray diffraction (Synchrotron WAXD) at the Shanghai Synchrotron Radiation Facility (SSRF), beamline station BL14B1, electron beam energy 10 KeV, a fixed distance of 280 mm between the sample and the detector, and a MarCCD detector to collect two-dimensional images with an exposure time of 120 s. The oriented amorphous fraction (A2) and the oriented crystalline fraction A(3) were obtained. The orientation degree X of the product is the sum of the oriented crystalline fraction and the oriented amorphous fraction (i.e., X = A2 + A3). The specific calculation formula is as follows:

[0110] Where I(S) represents the intensity distribution of the diffraction peak, which can be read from the graph; S is the reciprocal vector in reciprocal space (S = 2sinθ / λ), and the unit is nm. -1 ; λ is the wavelength, 2θ is the scattering angle; Φ is the angle between the scattering vector and the stretching direction (i.e., the azimuth angle).

[0111] Tear linearity test

[0112] To more clearly determine tear linearity, the following method was used. A 40mm-long incision was made at one end of a 300mm-long specimen. Using a clamp, the incision was placed parallel to the tube's length at the center of the tube. The tube was torn at a speed of 200mm / min from the incision to the other end. The weight of each torn tube was measured, and the weight ratio was calculated. The closer the ratio is to 50%:50%, the higher the tear linearity.

[0113] Tear strength test

[0114] After making a 40mm cut with a knife, take a 200mm sample and run it through a tensile testing machine at a speed of 200mm / min. Measure the maximum force at that moment, which is the tear strength. Perform three measurements on samples of the same composition and calculate the weighted average.

[0115] Tensile strength test

[0116] Tested in accordance with UL 224-2021, method 5.4.

[0117] Example 1-1

[0118] Masterbatch processing

[0119] Ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 0.1 were added to a high-speed mixer and stirred for 3-5 minutes. The material obtained in the above process was fed into a twin-screw extruder with a diameter of 30 mm and extruded at a screw speed of 45 rpm and a temperature of 130-200°C (the temperature range consists of 10 zones: zone 1 is 130°C, zone 2 is 160°C, zone 3 is 180°C, zone 4 is 185°C, zone 5 is 190°C, zone 6 is 190°C, zone 7 is 195°C, zone 8 is 195°C, zone 9 is 195°C, and zone 10 is 195°C, and the die temperature is set to 200°C). The extruder was then stretched into strands and water-cooled for pelletizing to form masterbatch pellets.

[0120] Extruded pipes

[0121] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. A full-flight screw was used, and the extrusion temperature was 130-190°C (extrusion temperatures were as follows: Zone 1 130°C, Zone 2 180°C, Zone 3 190°C, Flange Zone 190°C, Head Zone 190°C, and Die Zone 190°C). The draw ratio was controlled at 9.7, and the molecular chain orientation of the extruded tube was measured to be 50%. The resulting tube had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0122] Example 1-2

[0123] Masterbatch processing

[0124] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) was replaced with ethylene-ethyl acrylate copolymer (EEA, ELVALOY TM AC 2116), the same method as in Example 1-1 was used for production.

[0125] Extruded pipes

[0126] Molding was performed in the same manner as in Example 1-1 except that the stretching ratio was controlled to 9.8.

[0127] Examples 1-3

[0128] Masterbatch processing

[0129] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same method as in Example 1-1 was used to produce a butyl acrylate copolymer (EBA, AC 3717) except that the butyl acrylate copolymer (EBA, AC 1218) was replaced with an ethylene-butyl acrylate copolymer (EBA, AC 3717).

[0130] Extruded pipes

[0131] Molding was performed in the same manner as in Example 1-1.

[0132] Examples 1-4

[0133] Masterbatch processing

[0134] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The production was carried out in the same manner as in Example 1-1 except that ethylene-methyl methacrylate copolymer (EMMA, Sumitomo CM8014) was used instead of AC 1218.

[0135] Extruded pipes

[0136] Molding was performed in the same manner as in Example 1-1 except that the stretching ratio was controlled to 9.9.

[0137] Examples 1-5

[0138] Masterbatch processing

[0139] The production was carried out in the same manner as in Example 1-1.

[0140] Extruded pipes

[0141] The molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was controlled to be 5 and the molecular chain orientation degree of the extruded pipe was measured to be 23%.

[0142] Examples 1-6

[0143] Masterbatch processing

[0144] The production was carried out in the same manner as in Example 1-1.

[0145] Extruded pipes

[0146] The molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was controlled to be 7.4 and the molecular chain orientation degree of the extruded pipe was measured to be 30%.

[0147] Examples 1-7

[0148] Masterbatch processing

[0149] The production was carried out in the same manner as in Example 1-1.

[0150] Extruded pipes

[0151] The molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was controlled to be 15.3 and the molecular chain orientation degree of the extruded pipe was measured to be 90%.

[0152] Examples 1-8

[0153] Masterbatch processing

[0154] The production was carried out in the same manner as in Example 1-1.

[0155] Extruded pipes

[0156] The molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was controlled to be 17.5 and the molecular chain orientation degree of the extruded pipe was measured to be 95%.

[0157] Examples 1-9

[0158] Masterbatch processing

[0159] The production was carried out in the same manner as in Example 1-1.

[0160] Extruded pipes

[0161] Molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was controlled to be 8.0 and the molecular chain orientation degree of the extruded pipe was measured to be 35%.

[0162] Examples 1-10

[0163] Masterbatch processing

[0164] The production was carried out in the same manner as in Example 1-1.

[0165] Extruded pipes

[0166] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. Using a full-flight screw, the extrusion temperature ranged from 130°C to 190°C (zone 1: 130°C, zone 2: 180°C, zone 3: 190°C, flange zone: 190°C, die zone: 190°C), and the draw ratio was controlled at 29.9. Extrusion molding yielded tubes with an inner diameter of 0.4mm, an outer diameter of 1.06mm, and a wall thickness of 0.33mm. The molecular chain orientation of the extruded tubes was measured to be 80%.

[0167] Examples 1-11

[0168] Masterbatch processing

[0169] The production was carried out in the same manner as in Example 1-1.

[0170] Extruded pipes

[0171] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. A full-flight screw was used, and the extrusion temperature was maintained at 130-190°C (extrusion temperatures were as follows: Zone 1 130°C, Zone 2 180°C, Zone 3 190°C, Flange Zone 190°C, Head Zone 190°C, and Die Zone 190°C). The draw ratio was controlled at 55.6, and the resulting tubes had an inner diameter of 3.0 mm, an outer diameter of 4.04 mm, and a wall thickness of 0.52 mm. The molecular chain orientation of the extruded tubes was measured to be 80%.

[0172] Comparative Example 1-1

[0173] Masterbatch processing

[0174] Low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) and antioxidant (Antioxidant 1010) (mass ratio) = 60 / 0.1 were added to a high-speed mixer and stirred for 3-5 minutes. The material obtained in the above process was put into a twin-screw extruder with a cylinder diameter of 30 mm, and extruded at a screw speed of 45 rpm and an extrusion temperature of 130-200° C. (the temperature range is 10 zones, zone 1 is 130° C., zone 2 is 160° C., zone 3 is 180° C., zone 4 is 185° C., zone 5 is 190° C., zone 6 is 190° C., zone 7 is 195° C., zone 8 is 195° C., zone 9 is 195° C., and zone 10 is 195° C., and the head temperature is set to 200° C.), followed by stranding, water-cooling and pelletizing to form masterbatch pellets.

[0175] Extruded pipes

[0176] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. A full-flight screw was used, and the extrusion temperature was 130-190°C (130°C for zone 1, 180°C for zone 2, 190°C for zone 3, 190°C for flange zone, 190°C for die zone, and 190°C for die zone). The draw ratio was controlled at 10.5, and the molecular chain orientation of the extruded tube was measured to be 50%. The resulting tube had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0177] Comparative Example 1-2

[0178] Masterbatch processing

[0179] The same method as Comparative Example 1-1 was used to produce the product except that the low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) was replaced with an ethylene-vinyl acetate copolymer (EVA, 7350M).

[0180] Extruded pipes

[0181] Molding was performed in the same manner as in Comparative Example 1-1 except that the stretching ratio was 10.2.

[0182] Comparative Examples 1-3

[0183] Masterbatch processing

[0184] In addition to replacing low-density polyethylene (LDPE, lyondellbasellLupolen 2426K) with polyolefin elastomer (POE, ENGAGE TM 8180), the same method as Comparative Example 1 was used for manufacturing.

[0185] Extruded pipes

[0186] Molding was performed in the same manner as in Comparative Example 1-1 except that the stretching ratio was 10.9.

[0187] Comparative Examples 1-4

[0188] Masterbatch processing

[0189] The production was carried out in the same manner as in Example 1-1.

[0190] Extruded pipes

[0191] Molding was carried out in the same manner as in Example 1-1 except that the stretching ratio was 4 and the molecular chain orientation degree of the extruded pipe was measured to be 15%.

[0192] Comparative Examples 1-5

[0193] The commercially available PTFE tearable sheath is used, with a specification of AWG 24F.

[0194] For the easily peelable tubes prepared above, the molecular chain orientation of the extruded tubes was measured during extrusion using the aforementioned orientation determination method; tear linearity was measured using the aforementioned tear linearity test method; and tear strength was measured using the aforementioned tear strength test method. The results for Examples 1-1 to 1-11 are shown in Table 1-1, and the results for Comparative Examples 1-1 to 1-5 are shown in Table 1-2.

[0195] Table 1-1 Examples 1-1 to 1-11

[0196] Table 1-2 Comparative Examples 1-1 to 1-5

[0197] As shown in Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-3, easily peelable tubing made from polyolefin and its copolymer resins is significantly dependent on the type of polymer. EMA, EEA, EBA, and EMMA can all be used to prepare easily peelable tubing, demonstrating that these types of ethylene-acrylic acid copolymers can all be used to prepare easily peelable tubing. As shown in Examples 1-1, 1-5 to 1-11, and Comparative Example 1-4, in addition to the type of polymer, the molecular chain orientation of the extruded tubing must be controlled within a range of 23%-95% during the extrusion process. This results in a tubing with a molecular chain orientation of 23%-95% and linear tear resistance. As shown in Examples 1-1 to 1-11 and Comparative Example 1-5, the easily peelable tubing of the present application exhibits lower tear strength than PTFE easily peelable tubing and can replace PTFE tearable tubing.

[0198] Example 2-1

[0199] Masterbatch processing

[0200] Ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (Antioxidant 1010) (mass ratio) = 60 / 10 / 0.1, added to a high-speed mixer and stirred for 3-5 minutes. The material obtained in the above process was fed into a twin-screw extruder with a diameter of 30 mm, and extruded at a screw speed of 45 rpm and a temperature of 130-200° C. (the temperature range consists of 10 zones: zone 1 is 130° C., zone 2 is 160° C., zone 3 is 180° C., zone 4 is 185° C., zone 5 is 190° C., zone 6 is 190° C., zone 7 is 195° C., zone 8 is 195° C., zone 9 is 195° C., and zone 10 is 195° C., and the die head temperature is set to 200° C.), then stretched into strands, water-cooled and pelletized to form masterbatch pellets.

[0201] Extruded pipes

[0202] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. A full-flight screw was used, and the extrusion temperature was 130-190°C (130°C for zone 1, 180°C for zone 2, 190°C for zone 3, 190°C for flange zone, 190°C for die zone, and 190°C for die zone). The draw ratio was controlled at 9.9, and the molecular chain orientation of the extruded tube was measured to be 50%. The resulting tube had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0203] Example 2-2

[0204] Masterbatch processing

[0205] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-ethyl acrylate copolymer (EEA, ELVALOY TM The same procedure as in Example 2-1 was carried out except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 10 / 0.1.

[0206] Extruded pipes

[0207] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.1.

[0208] Example 2-3

[0209] Masterbatch processing

[0210] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low-density polyethylene (LDPE, lyondellbasellLupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-butyl acrylate copolymer (EBA, AC 3717) / low-density polyethylene (LDPE, lyondellbasellLupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1, the same method as in Example 2-1 was used for production.

[0211] Extruded pipes

[0212] Molding was performed in the same manner as in Example 2-1.

[0213] Examples 2-4

[0214] Masterbatch processing

[0215] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TMAC 1218) / low-density polyethylene (LDPE, lyondellbasellLupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl methacrylate copolymer (EMMA, Sumitomo CM8014) / low-density polyethylene (LDPE, lyondellbasellLupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1. The same method as in Example 2-1 was used for the production.

[0216] Extruded pipes

[0217] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.3.

[0218] Examples 2-5

[0219] Masterbatch processing

[0220] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / Linear Low Density Polyethylene (LLDPE, The same procedure as in Example 2-1 was carried out except that the LLDPE (218W) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1.

[0221] Extruded pipes

[0222] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0223] Examples 2-6

[0224] Masterbatch processing

[0225] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / Medium Density Polyethylene (MDPE, DOW AXELERON TMThe production was carried out in the same manner as in Example 2-1 except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 10 / 0.1.

[0226] Extruded pipes

[0227] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0228] Examples 2-7

[0229] Masterbatch processing

[0230] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same procedure as in Example 2-1 was carried out except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 10 / 0.1.

[0231] Extruded pipes

[0232] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.5.

[0233] Examples 2-8

[0234] Masterbatch processing

[0235] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / Polyolefin elastomer (POE, ENGAGE TM The production was carried out in the same manner as in Example 2-1 except that the mass ratio of the antioxidant (antioxidant 1010) was 60 / 10 / 0.1.

[0236] Extruded pipes

[0237] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.6.

[0238] Examples 2-9

[0239] Masterbatch processing

[0240] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same method as in Example 2-1 was used for production except that the mass ratio of AC 1218) / ethylene-vinyl acetate copolymer (EVA, 7350M) / antioxidant (antioxidant 1010) was 60 / 10 / 0.1.

[0241] Extruded pipes

[0242] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0243] Example 2-10

[0244] Masterbatch processing

[0245] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same method as in Example 2-1 was used for production except that the mass ratio of the antioxidant (Antioxidant 1010) was 20 / 10 / 0.1.

[0246] Extruded pipes

[0247] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.5.

[0248] Example 2-11

[0249] Masterbatch processing

[0250] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TMAC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The production was carried out in the same manner as in Example 2-1 except that the ratio of AC 1218) / low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (Antioxidant 1010) was 75 / 10 / 0.1.

[0251] Extruded pipes

[0252] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.8.

[0253] Example 2-12

[0254] Masterbatch processing

[0255] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The production was carried out in the same manner as in Example 2-1 except that the mass ratio of the antioxidant (Antioxidant 1010) was 90 / 10 / 0.1.

[0256] Extruded pipes

[0257] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.7.

[0258] Example 2-13

[0259] Masterbatch processing

[0260] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TMThe same method as in Example 2-1 was used for production except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 40 / 0.1.

[0261] Extruded pipes

[0262] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.6.

[0263] Examples 2-14

[0264] Masterbatch processing

[0265] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same method as in Example 2-1 was used for production except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 60 / 0.1.

[0266] Extruded pipes

[0267] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.7.

[0268] Example 2-15

[0269] Masterbatch processing

[0270] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / low density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The production was carried out in the same manner as in Example 2-1 except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 80 / 0.1.

[0271] Extruded pipes

[0272] Molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.8.

[0273] Example 2-16

[0274] Masterbatch processing

[0275] The production was carried out in the same manner as in Example 2-1.

[0276] Extruded pipes

[0277] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 5.8 and the molecular chain orientation degree of the extruded pipe was measured to be 23%.

[0278] Example 2-17

[0279] Masterbatch processing

[0280] The production was carried out in the same manner as in Example 2-1.

[0281] Extruded pipes

[0282] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 7.3 and the molecular chain orientation degree of the extruded pipe was measured to be 30%.

[0283] Example 2-18

[0284] Masterbatch processing

[0285] The production was carried out in the same manner as in Example 2-1.

[0286] Extruded pipes

[0287] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 15.8 and the molecular chain orientation degree of the extruded pipe was measured to be 90%.

[0288] Example 2-19

[0289] Masterbatch processing

[0290] The production was carried out in the same manner as in Example 2-1.

[0291] Extruded pipes

[0292] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 17.9 and the molecular chain orientation degree of the extruded pipe was measured to be 95%.

[0293] Example 2-20

[0294] Masterbatch processing

[0295] The production was carried out in the same manner as in Example 2-1.

[0296] Extruded pipes

[0297] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to 8.1 and the molecular chain orientation degree of the extruded pipe was measured to be 35%.

[0298] Comparative Example 2-1

[0299] Masterbatch processing

[0300] Low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (Antioxidant 1010) (mass ratio) = 60 / 0.1 was added to a high-speed mixer and stirred for 3-5 minutes. The material obtained in the above process was put into a twin-screw extruder with a cylinder diameter of 30 mm, and extruded at a screw speed of 45 rpm and an extrusion temperature of 130-200° C. (the temperature range is 10 zones, with Zone 1 being 130° C., Zone 2 being 160° C., Zone 3 being 180° C., Zone 4 being 185° C., Zone 5 being 190° C., Zone 6 being 190° C., Zone 7 being 195° C., Zone 8 being 195° C., Zone 9 being 195° C., and Zone 10 being 195° C., and the die head temperature being set at 200° C.), followed by stranding, water-cooling and pelletizing to ultimately form masterbatch pellets.

[0301] Extruded pipes

[0302] The masterbatch pellets obtained above were formed into tubes using a single-screw extruder. A full-flight screw was used, and the extrusion temperature was 130-190°C (130°C for zone 1, 180°C for zone 2, 190°C for zone 3, 190°C for flange zone, 190°C for die zone, and 190°C for die zone). The draw ratio was controlled at 10.5, and the molecular chain orientation of the extruded tube was measured to be 50%. The resulting tube had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0303] Comparative Example 2-2

[0304] Masterbatch processing

[0305] In addition to replacing low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / antioxidant (Antioxidant 1010) (mass ratio) = 60 / 0.1 with polyolefin elastomer (POE, ENGAGE TM The same method as in Comparative Example 2-1 was used for production except that the mass ratio of the antioxidant (antioxidant 1010) was 60 / 0.1.

[0306] Extruded pipes

[0307] Molding was performed in the same manner as in Comparative Example 2-1 except that the stretching ratio was controlled to 10.9.

[0308] Comparative Examples 2-3

[0309] Masterbatch processing

[0310] The same method as Comparative Example 2-1 was used to manufacture the product except that the low-density polyethylene (LDPE, LyondellBasellLupolen 2426K) / antioxidant (Antioxidant 1010) (mass ratio) = 60 / 0.1 was replaced with ethylene-vinyl acetate copolymer (EVA, 7350M) / antioxidant (Antioxidant 1010) (mass ratio) = 60 / 0.1.

[0311] Extruded pipes

[0312] Molding was performed in the same manner as in Comparative Example 2-1 except that the stretching ratio was controlled to 10.2.

[0313] Comparative Examples 2-4

[0314] Masterbatch processing

[0315] The production was carried out in the same manner as in Example 2-1.

[0316] Extruded pipes

[0317] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 4 and the molecular chain orientation degree of the extruded pipe was measured to be 15%.

[0318] Comparative Examples 2-5

[0319] The commercially available PTFE tearable sheath is used, with a specification of AWG 24F.

[0320] For the easily peelable tubes prepared above, the preparation parameters for Examples 2-1 to 2-20 are shown in Table 2-1, and the preparation parameters for Comparative Examples 2-1 to 2-5 are shown in Table 2-2. The molecular chain orientation of the extruded tubes during extrusion was determined using the aforementioned orientation determination method, and the orientation of the commercially available PTFE tearable sheath in Comparative Example 2-5 was determined. Tear linearity was determined using the aforementioned tear linearity test method, tear strength was determined using the aforementioned tear strength test method, and tensile strength was determined using the aforementioned tensile strength test method. The measurement results for Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-5 are shown in Table 2-3.

[0321] Table 2-1 Preparation condition parameters of Examples 2-1 to 2-20

[0322] Table 2-2 Preparation condition parameters of comparative examples 2-1 to 2-5

[0323] Table 2-3 Measurement results of Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-5

[0324] It can be seen from Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 that the easy-to-peel tubes made of polyolefins and their copolymer resins are closely related to the type of polymer. EMA, EEA, EBA and EMMA can all be used to prepare easy-to-peel tubes, which means that this type of ethylene-acrylic acid copolymers can all be used to prepare easy-to-peel tubes. It can be seen from Examples 2-1, 2-16 to 2-20 and Comparative Example 2-4 that in addition to the type of polymer, it is also necessary to control the molecular chain orientation of the extruded tube in the extrusion process to be 23%-95%, that is, the molecular chain orientation of the final easy-to-peel tube is 23%-95%, and has linear tearing properties. It can be seen from Example 2-1 and Example 1-1 that the addition of a reinforcing agent can increase the tensile strength of the easy-to-peel tube. The present application provides an easy-to-peel tube made of polyolefins and their copolymer resins and a reinforcing agent. Its tear strength is lower than that of PTFE easy-to-peel tubes, its tensile strength is higher, and there is no adhesion to the internal material. It can completely replace PTFE easy-to-peel tubes and provides a new choice for easy-to-peel tubes.

[0325] The above are only preferred embodiments of the present application and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of the present invention.

Claims

1. An easily peelable pipe that has linear tearability in the longitudinal direction of the pipe, characterized in that, The material for preparing the easily peelable pipe comprises an ethylene-acrylate copolymer as the matrix resin, and the extrusion process controls the molecular chain orientation degree of the extruded pipe to be 23%-95%.

2. The peelable pipe according to claim 1, characterized in that, The molecular chain orientation degree of the extruded pipe is 30%-90%.

3. The easily peelable pipe according to any one of claims 1 to 2, characterized in that, The ethylene-acrylate copolymer includes at least one of ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, and ethylene-methyl methacrylate copolymer.

4. The easily peelable pipe according to any one of claims 1 to 3, characterized in that The ethylene-acrylate copolymer has a melt index of (0.5-10) g / 10min and an acrylic acid content of 9wt%-30wt%; and / or, The ethylene-acrylate copolymer has a tear strength lower than 75 kN / m; and / or, The ethylene-acrylate copolymer has a tensile strength of 15-24 Mpa.

5. The easily peelable pipe according to any one of claims 1 to 4, characterized in that, Calculated by weight, the material for preparing the easily peelable pipe comprises the following components: Ethylene-acrylate copolymer: 20-90 parts; Reinforcing agent: 10-80 parts.

6. The peelable pipe according to claim 5, wherein The reinforcing agent includes at least one of polyethylene, polyolefin elastomer, and ethylene-vinyl acetate copolymer.

7. The peelable pipe according to claim 6, wherein, The polyethylene is low-density polyethylene, and the low-density polyethylene satisfies: the melt index is (0.3-7) g / 10min and the tensile strength is 17-30 Mpa; and / or, The polyethylene is linear low-density polyethylene, and the linear low-density polyethylene satisfies: the melt index is (0.3-10) g / 10min and the tensile strength is 20-35 Mpa; and / or, The polyethylene is medium-density polyethylene, and the medium-density polyethylene satisfies: the melt index is (0.3-10) g / 10min and the tensile strength is 25-35 Mpa; and / or, The polyethylene is high-density polyethylene, and the high-density polyethylene satisfies: the melt index is (0.3-10) g / 10min and the tensile strength is 28-40 Mpa; and / or, The polyolefin elastomer satisfies: the melt index is (0.5-5) g / 10min, the tensile strength is 18-40 Mpa, and the melting temperature is 70-110 °C; and / or, The ethylene-vinyl acetate copolymer satisfies: the melt index is (0.5-7) g / 10min, the tensile strength is 16-25 Mpa, and the vinyl acetate content does not exceed 20%.

8. The peelable pipe according to any one of claims 1 to 7, characterized in that, Calculated by weight, the material for preparing the easily peelable pipe further includes at least one of the following additives: Antioxidant: 0.05-0.3 parts; Lubricant: 0.05-0.1 parts; Among them, the antioxidant includes at least one of asymmetric hindered phenolic antioxidants, aromatic amine antioxidants, thioether antioxidants, and phosphite antioxidants; The lubricant includes at least one of PTFE powder, zinc stearate, magnesium stearate, silicone, calcium stearate, or ethylene bis-stearamide.

9. The easily peelable pipe according to any one of claims 1 to 8, characterized in that, The ratio representing the linear tearability is in the range of 50%:50% to 48%:52%; and / or, The inner diameter of the easily peelable pipe is 0.3-16 mm; and / or, The wall thickness of the easily peelable pipe is 0.1-2 mm.

10. An easily peelable pipe having linear tearability in the longitudinal direction of the pipe, characterized in that, The material for preparing the easily peelable pipe comprises an ethylene-acrylate copolymer as the matrix resin, and the degree of molecular chain orientation of the easily peelable pipe is 23%-95%.

11. The peelable pipe according to claim 10, wherein, The degree of molecular chain orientation of the easily peelable pipe is 30%-95%.

12. The peelable pipe according to claim 10, wherein The degree of molecular chain orientation of the easily peelable pipe is 30%-90%.

13. The peelable pipe according to claim 10, wherein The degree of molecular chain orientation of the easily peelable pipe is 35%-90%.

14. A method for preparing a peelable pipe according to any one of claims 1 to 13, characterized in that, It includes the following steps: Masterbatch processing: Mix the raw materials evenly, extrude, draw into strips and pelletize through an extrusion device to obtain masterbatch particles, and the raw materials include an ethylene-acrylate copolymer; Extrusion into pipe: Extrude the masterbatch particles obtained above through an extruder to obtain the easily peelable pipe, wherein the degree of molecular chain orientation of the extruded pipe is controlled to be 23%-95%.

15. The preparation method according to claim 14, characterized in that, In the masterbatch processing step, the raw materials further include at least one of a reinforcing agent, an antioxidant and a lubricant; and / or, In the masterbatch processing step, the mixing time is 3-5 min; and / or, In the masterbatch processing step, the extrusion temperature of the extrusion device is 130-200 °C; and / or, In the extrusion into pipe step, the degree of molecular chain orientation of the extruded pipe is 30%-90%.

16. The preparation method according to claim 14, wherein In the masterbatch processing step and the extrusion into pipe step, the extrusion temperature of the extruder is 130-190 °C; and / or, In the extrusion into pipe step, the draw ratio of the extruded pipe is 5-60; and / or, In the extrusion into pipe step, the draw ratio of the extruded pipe is 7-30.

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