Easily peelable heat shrink tubing and manufacturing method therefor

Abstract

Easily peelable heat shrink tubing and a manufacturing method therefor. The heat shrink tubing uses an ethylene-acrylate copolymer as a base resin. Because ethylene-acrylate is a copolymer and contains acrylate side groups, crystallization of the ethylene-acrylate copolymer is disrupted, the distance between main-chain ethylene-based molecules is increased, and the entanglement of structures of the molecules are reduced, so that the cohesive strength of ethylene-acrylate molecular chains is decreased. By controlling the orientation degree of internal molecular chains of the ethylene-acrylate copolymer of extruded tubing in an extrusion process, the orientation degree is maintained within the range of 40% to 95%, so that the molecular chains and segments of the ethylene-acrylate copolymer extend in an orientation direction from a freely coiled disordered state, thereby further reducing the entanglement of structures of the molecules. When the easily peelable heat shrink tubing shrinks by more than 35% at 200°C, the orientation degree of the molecular chains of the easily peelable heat shrink tubing ranges from 30% to 85%, so that room-temperature tearability of the easily peelable heat shrink tubing is realized.

Description

Easy-to-peel heat shrink tube and preparation method thereof

[0001] Cross-references

[0002] This application claims priority to the Chinese invention patent application with application number 2023118393502 filed on December 29, 2023, entitled “A kind of easy-to-peel heat shrinkable tube and its preparation method”, the contents of which are incorporated herein by reference.

[0003] This application claims priority to Chinese invention patent application No. 2023118393466, filed on December 29, 2023, entitled “A Type of Easy-to-Peel Heat Shrink Tube,” the contents of which are incorporated herein by reference. Technical Field

[0004] The present application relates to the field of pipe technology, and in particular to an easy-to-peel heat shrink tube and a preparation method thereof. Background Art

[0005] Easy-peel heat shrink tubing is primarily used for protecting or assisting in shrinking precision devices, electronic components, and medical devices. For example, it can assist in shrinking non-shrinkable polymer tubing onto a corresponding mandrel in medical devices or in medical laser welding applications. After completing the assisted shrinking process, the easy-peel heat shrink tubing can be easily and residue-free removed from any angle along the axial direction (one end of the tubing is pre-defected to facilitate peeling) without mechanical removal (knife cutting, scoring, cutting, grinding, etc., which can cause defects or damage to the internal material). After removing the easy-peel heat shrink tubing, the surface of the non-shrinkable polymer tubing is smooth, defect-free, and residue-free.

[0006] At present, the room temperature tearable heat shrink tubing available on the market is generally fluororesin (FEP) easy-to-peel heat shrink tubing, and there are relatively few easy-to-peel heat shrink tubing made of polyolefin and its copolymers. Summary of the Invention

[0007] The main purpose of this application is to provide an easy-to-peel heat shrink tube made of polyolefin and its copolymer resin, which has low tear strength and no adhesion to the internal material. It can completely replace FEP easy-to-peel heat shrink tube and provide a new option for easy-to-peel heat shrink tube.

[0008] In the first aspect, an embodiment of the present application provides an easy-to-peel heat shrinkable tube having linear tearing properties in the length direction of the tube. The material for preparing the easy-to-peel heat shrinkable tube comprises ethylene-acrylate copolymer as a matrix resin, and the extrusion process controls the molecular chain orientation of the extruded tube to be 40%-95%. The shrinkage rate of the easy-to-peel heat shrinkable tube when heated at 200°C is more than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation of the easy-to-peel heat shrinkable tube is 30%-85%.

[0009] In some embodiments of the present application, the extrusion process controls the molecular chain orientation of the extruded tube to be 50%-90%, the shrinkage rate of the easy-to-peel heat shrinkable tube when heated at 200°C is more than 35%, and after shrinking by more than 35% at 200°C, the molecular chain orientation of the easy-to-peel heat shrinkable tube is 40%-85%.

[0010] In some embodiments of the present application, an irradiation process is further included after the extrusion process, and the irradiation dose provided by the irradiation equipment in the irradiation process is 100-300 KGy.

[0011] 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).

[0012] 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%.

[0013] In some embodiments of the present application, the ethylene-acrylate copolymer has a tear strength lower than 75 kN / m.

[0014] In some embodiments of the present application, the ethylene-acrylate copolymer has a tensile strength of 15-24 MPa.

[0015] In some embodiments of the present application, the material for preparing the easily peelable heat shrinkable tube includes the following components, calculated by weight:

[0016] Ethylene-acrylate copolymer: 20-90 parts;

[0017] Enhancer: 10-80 parts.

[0018] In some embodiments of the present application, the reinforcing agent includes at least one of polyethylene, polyolefin elastomer, and ethylene-vinyl acetate copolymer.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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%.

[0025] In some embodiments of the present application, the material for preparing the easily peelable heat shrinkable tube further includes at least one of the following additives, calculated by weight:

[0026] Antioxidant 0.05-0.3 parts;

[0027] Lubricant 0.05-0.1 parts;

[0028] Wherein, the antioxidant includes but is not limited to asymmetric hindered phenol antioxidants, aromatic amine antioxidants, thioether antioxidants, and phosphite antioxidants;

[0029] The lubricant includes but is not limited to FEP powder, zinc stearate, magnesium stearate, silicone, calcium stearate or ethylene bisstearamide.

[0030] In some embodiments of the present application, the ratio representing the tear linearity is in the range of 50%:50% to 48%:52%.

[0031] In some embodiments of the present application, the inner diameter of the easy-to-peel heat shrink tube is 0.3-16 mm.

[0032] In some embodiments of the present application, the wall thickness of the easily peelable heat shrink tube is 0.1-2 mm.

[0033] Secondly, an embodiment of the present application provides an easy-to-peel heat shrink tube having linear tearing properties in the length direction of the tube. The material for preparing the easy-to-peel heat shrink tube contains ethylene-acrylate copolymer as a matrix resin. The shrinkage rate of the easy-to-peel heat shrink tube when heated at 200°C is more than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation degree of the easy-to-peel heat shrink tube is 30%-85%.

[0034] In some embodiments of the present application, the shrinkage rate of the easily peelable heat shrinkable tube when heated at 200°C is greater than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 35%-85%.

[0035] In some embodiments of the present application, the shrinkage rate of the easily peelable heat shrinkable tube when heated at 200°C is greater than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 40%-85%.

[0036] In a third aspect, an embodiment of the present application provides a method for preparing an easily peelable heat shrink tubing, 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 pipes: Extruding the masterbatch particles obtained above into pipes through an extruder to obtain semi-finished pipes, wherein the orientation degree of the molecular chains of the extruded pipes is controlled to be 40%-95%;

[0039] Irradiation process: The semi-finished pipes are irradiated by irradiation equipment, and the irradiation dose is controlled to be 100-300KGy to obtain irradiated pipes;

[0040] Expansion molding: The irradiated tube is expanded at 130-260°C, and then cooled and formed to obtain an easily peelable heat shrinkable tube; wherein, after the easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200°C, the molecular chain orientation degree of the tube is 30%-85%.

[0041] 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.

[0042] In some embodiments of the present application, in the masterbatch processing step, the mixing time is 3-5 minutes.

[0043] In some embodiments of the present application, in the masterbatch processing step, the extrusion temperature of the extrusion equipment is 130-200°C.

[0044] 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 50%-90%.

[0045] In some embodiments of the present application, after the easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200° C., the molecular chain orientation degree is 40%-85%.

[0046] In some embodiments of the present application, in the masterbatch processing step and the tube extrusion step, the extrusion temperature of the extruder is 130-190°C.

[0047] In some embodiments of the present application, in the extrusion tube step, the stretching ratio of the extruded tube is 7-60.

[0048] In some embodiments of the present application, in the extrusion tube step, the stretching ratio of the extruded tube is 8.5-30.

[0049] Beneficial effects that this application can achieve:

[0050] The easy-to-peel heat shrink tubing provided in the present application adopts ethylene-acrylate copolymer as the matrix 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, resulting in a decrease in the cohesive strength of the ethylene-acrylate molecular chain; further, the orientation degree of the internal molecular chains of the ethylene-acrylate copolymer in the extruded tube is controlled through the extrusion process to ensure that the orientation degree is in the range of 40%-95%, so that the ethylene-acrylate copolymer molecular chains and chain segments stretch from a freely curled disordered state to an oriented direction, further reducing the entanglement structure of the molecules; further, after the easy-to-peel heat shrink tubing shrinks by more than 35% at a temperature of 200°C, the orientation degree of the molecular chains of the easy-to-peel heat shrink tubing is 30%-85%, thereby achieving the room-temperature tearability of the easy-to-peel heat shrink tubing. DETAILED DESCRIPTION

[0051] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Polymer materials exist as entangled chains of molecules, like a ball of 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 a certain degree of molecular chain orientation during the extrusion process, resulting in easily peelable tubing with linear tear resistance along its length. This is likely due to the unique structure of ethylene-acrylate copolymers, which contain side groups of methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate. These side groups affect molecular crystallization and entanglement, increasing the distance between main chain molecules and reducing molecular entanglement, resulting in a decrease in the cohesive strength of the ethylene-acrylate copolymer chains. Furthermore, the degree of orientation within the ethylene-acrylate copolymer is controlled during the extrusion process, ensuring that the orientation is within a certain range. This allows the ethylene-acrylate copolymer chains and segments to stretch from a freely coiled, disordered state to an oriented direction, further reducing molecular entanglement and achieving the tearability of the tube. This ordered change in orientation significantly increases the strength of the copolymer along the length of the tube, while decreasing the strength perpendicular to the tube, further improving the tube's strength and tear resistance. The tear-resistant tubes are then irradiated and expanded to form heat-shrink tubing, which exhibits the same tear resistance as before expansion.

[0057] In this application, ethylene-acrylate copolymer is used as the matrix resin, and the orientation degree of the internal molecular chain of ethylene-acrylate copolymer is controlled through the extrusion process to ensure that the orientation degree is in the range of 40%-95%. Furthermore, the extruded easy-to-peel tube is subjected to irradiation cross-linking through an irradiation process, so that it is transformed from an ordinary two-dimensional linear molecular structure into a three-dimensional network molecular structure. The three-dimensional network molecular structure not only has a curing effect on the orientation of the molecular chain of the extruded tube in the extrusion process, but also can realize the subsequent expansion process. However, at an expansion temperature of 130-260°C, the oriented three-dimensional network molecules will shrink, which will change their orientation degree. We control the cross-linking degree of ethylene-acrylate copolymer during the irradiation process by controlling the appropriate irradiation dose, and finally achieve that after the easy-to-peel heat shrink tube shrinks by more than 35% at a temperature of 200°C, the orientation degree of the molecular chain of the easy-to-peel heat shrink tube is 30%-85%, so that it has the performance of being tearable at room temperature.

[0058] In some embodiments, the extrusion process controls the molecular chain orientation of the extruded tube to be 50%-90%. After the shrinkage rate of the easy-to-peel heat shrinkable tube is more than 35% when heated at 200°C, the molecular chain orientation of the easy-to-peel heat shrinkable tube is 40%-85%. The orientation degrees in these two ranges make the linear tearing performance of the prepared easy-to-peel heat shrinkable tube more superior.

[0059] In some embodiments, an irradiation process is further included after the extrusion process, and the irradiation dose provided by the irradiation equipment in the irradiation process is 100-300KGy. The orientation degree of the easy-to-peel heat shrink tubing depends not only on the extrusion process, but also on the irradiation process. In the extrusion process, the stretching ratio is ensured by adjusting the difference between the extrusion speed of the tube blank from the die and the traction speed of the traction machine to pull the tube. The stretching ratio of the extruded tube is controlled between 7-60. Preferably, the stretching ratio of the extruded tube is controlled between 8.5 and 30, thereby obtaining an extruded tube with a molecular chain orientation degree of 40%-95%, that is, an easy-to-peel tube. After the extruded tube undergoes an irradiation process, by controlling the irradiation dose to 100-300KGy, the extruded tube can be transformed from an ordinary two-dimensional linear molecular structure to a three-dimensional network molecular structure after irradiation, obtaining a suitable cross-linking degree, and finally achieving the easy-to-peel heat shrink tubing. After shrinking by more than 35% at a temperature of 200°C, the molecular chain orientation degree of the easy-to-peel heat shrink tubing is 30%-85%, and it has the property of being tearable at room temperature. Of course, the tearability of the easily peelable heat shrink tubing can also be achieved by adding a crosslinking agent to the ethylene-acrylate copolymer and adjusting the irradiation dose during the irradiation process. The irradiation equipment can be an electron accelerator irradiation device, a radioisotope irradiation device, etc., and is not limited here.

[0060] 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.

[0061] 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.

[0062] In some embodiments, the ethylene-acrylate copolymer has a tear strength lower than 75 kN / m. The tear strength within this range facilitates better tearing of the heat shrink tube.

[0063] 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 heat shrinkable tube.

[0064] In order to further improve the tensile strength of the easy-to-peel heat shrink tubing, we can add polymers such as polyethylene (PE), polyolefin elastomer (POE), and 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 material for preparing the easy-to-peel heat shrink tubing includes the following components, calculated by weight:

[0065] Ethylene-acrylate copolymer: 20-90 parts;

[0066] Enhancer: 10-80 parts.

[0067] The addition of the reinforcing agent can improve the tensile strength of the molecular structure, and further control the orientation degree 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 40%-95%, so that the molecular chains and chain segments of the ethylene-acrylate copolymer and the reinforcing agent blend stretch from the freely curled and disordered state to the orientation direction, reducing the linear entanglement structure of the blend molecules. The reinforcing agent has a high degree of crystallinity or long chain branches. Reinforcing agents with high crystallinity, such as PE or EVA, will cause the crystallization of the reinforcing agent to transform from spherulites to monoclinic crystals during the extrusion stretching orientation of the pipe. 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. Reinforcing agents 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 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 agents and controlling the degree of orientation during the extrusion stretching process, the reinforcing agent is oriented in the ethylene-acrylate copolymer, and fiber-like reinforcing units appear along the orientation direction, further improving the tearability of the pipe. Therefore, the addition of a 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 of the pipe. Furthermore, the pipe is irradiated and cross-linked through an irradiation process, so that it changes from an ordinary two-dimensional linear molecular structure to a three-dimensional network molecular structure. The three-dimensional network molecular structure not only solidifies the orientation of the molecular chains of the extruded pipe in the extrusion process, but also realizes the subsequent expansion process. However, at an expansion temperature of 130-260°C, the oriented three-dimensional network molecules will shrink, which will change their orientation degree. By controlling the appropriate irradiation dose and the cross-linking degree of the blend molecules during the irradiation process, we finally achieve that after the easy-to-peel heat shrink tubing shrinks by more than 35% at a temperature of 200°C, the orientation degree of the molecular chains of the easy-to-peel heat shrink tubing is 30%-85%, making it tearable at room temperature.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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%.

[0074] Of course, to obtain a higher performance tubing, we can also add additives such as antioxidants and lubricants. In some embodiments, the material for preparing the easy-to-peel heat shrink tubing further includes at least one of the following additives: 0.05-0.3 parts of antioxidant; 0.05-0.1 parts of lubricant.

[0075] Antioxidants are beneficial to improving the antioxidant properties and aging resistance of easy-to-peel heat shrink tubing and extending the service life of easy-to-peel tubing. Antioxidants include but are not limited to asymmetric hindered phenol antioxidants, aromatic amine antioxidants, thioether antioxidants, and phosphite antioxidants.

[0076] 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).

[0077] 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).

[0078] Among them, thioether antioxidants include but are not limited to DLTP (dilauryl thiodipropionate), DSTDP (distearyl thiodipropionate), and DSTP (octadecyl thiodipropionate).

[0079] 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).

[0080] 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.

[0081] In some embodiments, the easily peelable heat shrink tubing comprises the following components, calculated in parts by weight:

[0082] 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.

[0083] 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 strength.

[0084] In some embodiments, the ratio representing tear linearity is in the range of 50%:50% to 48%:52%, and the closer the ratio is to 50%:50%, the better the tear linearity performance.

[0085] In some embodiments, the inner diameter of the easy-to-peel heat shrink tubing is 0.3-16 mm;

[0086] In some embodiments, the wall thickness of the easy-to-peel heat shrink tubing is 0.1-2 mm.

[0087] The present application also provides a method for preparing an easily peelable heat shrink tube, comprising the following steps:

[0088] Masterbatch processing: The raw materials are mixed evenly, extruded, stretched and pelletized through an extrusion device to obtain masterbatch particles. The raw materials include ethylene-acrylate copolymer;

[0089] Extrusion into pipes: Extruding the masterbatch particles obtained above into pipes through an extruder to obtain semi-finished pipes, wherein the orientation degree of the molecular chains of the extruded pipes is controlled to be 40%-95%;

[0090] Irradiation process: The semi-finished pipes are irradiated by irradiation equipment, and the irradiation dose is controlled to be 100-300KGy to obtain irradiated pipes;

[0091] Expansion molding: The irradiated tube is expanded at 130-260°C, and then cooled and formed to obtain an easily peelable heat shrinkable tube; wherein, after the easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200°C, the molecular chain orientation degree of the tube is 30%-85%.

[0092] 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.

[0093] In some embodiments, the mixing time in the masterbatch processing step is 3-5 minutes.

[0094] In some embodiments, in the masterbatch processing step, the extrusion temperature of the extrusion equipment is 130-200°C.

[0095] In some embodiments, during the extrusion step, the orientation degree of the molecular chains of the extruded tube is 50%-90%.

[0096] In some embodiments, during the expansion molding step, cooling and shaping are performed to obtain an easily peelable heat shrinkable tube, wherein after the easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200° C., the molecular chain orientation degree of the tube is 35%-85%.

[0097] In some embodiments, during the expansion molding step, cooling and shaping are performed to obtain an easily peelable heat shrinkable tube, wherein after the easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200° C., the molecular chain orientation degree of the tube is 40%-85%.

[0098] In some embodiments, the extrusion process controls the molecular chain orientation of the extruded tube to be 40%-95%. After the shrinkage rate of the easy-to-peel heat shrinkable tube is more than 35% when heated at 200°C, the molecular chain orientation of the easy-to-peel heat shrinkable tube is 35%-85%. The orientation degrees in these two ranges make the linear tearing performance of the prepared easy-to-peel heat shrinkable tube more superior.

[0099] In some embodiments, the extrusion process controls the molecular chain orientation of the extruded tube to be 50%-90%. After the shrinkage rate of the easy-to-peel heat shrinkable tube is more than 35% when heated at 200°C, the molecular chain orientation of the easy-to-peel heat shrinkable tube is 40%-85%. The orientation degrees in these two ranges make the linear tearing performance of the prepared easy-to-peel heat shrinkable tube more superior.

[0100] The orientation degree of the easy-to-peel heat shrink tubing depends not only on the extrusion process, but also on the irradiation process. During the extrusion process, the stretch ratio of the extruded tubing is controlled between 7 and 60. Preferably, the stretch ratio of the extruded tubing is controlled between 8.5 and 30, thereby obtaining an extruded tubing with a molecular chain orientation degree of 40% to 95%. The extruded tubing is subjected to an irradiation process, and by controlling the irradiation dose to 100 to 300 kGy, the extruded tubing can be transformed from an ordinary two-dimensional linear molecular structure to a three-dimensional network molecular structure after irradiation, thereby obtaining a suitable degree of crosslinking, and finally achieving an easy-to-peel heat shrink tubing with a molecular chain orientation degree of 30% to 85% after shrinking by more than 35% at a temperature of 200°C, and having the property of being tearable at room temperature. Of course, the tearability of the easy-to-peel heat shrink tubing can also be achieved by adding a crosslinking agent to the ethylene-acrylate copolymer and the reinforcing agent mixture, and then adjusting the irradiation dose during the irradiation process. The irradiation equipment can be an electron accelerator irradiation device or a radioisotope irradiation device, which is not limited here.

[0101] The easily peelable heat shrinkable tube of the present application has heat shrinkage and tear resistance, so it can be tightly attached to the adhered object and generate a tightening force on the adhered object. The magnitude of the tightening force is related to the shrinkage rate of the heat shrinkable tube. The greater the shrinkage rate, the greater the tightening force, and the smaller the shrinkage rate, the smaller the tightening force. Due to the radiation cross-linking property of the ethylene-acrylate copolymer, the cross-linking degree of the extruded tube can be controlled through the irradiation process, so that it changes from an ordinary two-dimensional linear molecular structure to a three-dimensional network molecular structure. The three-dimensional network molecular structure has a curing effect on the orientation of the internal molecular chains of the ethylene-acrylate copolymer during the extrusion process. Furthermore, by controlling the irradiation dose to control the cross-linking degree of the blend during the irradiation process, the obtained easily peelable heat shrinkable tube shrinks by more than 35% at a temperature of 200°C, and the molecular chain orientation degree reaches 30%-85%, thereby achieving the tearability of the heat shrinkable tube. FEP, however, is not resistant to radiation. The long, linear macromolecules within FEP cannot form a network structure through irradiation, which accounts for the difference in shrinkage between the two materials. Controlling the molecular chain orientation of the extruded tubing to 40%-95% during the extrusion process, and controlling the orientation of the resulting heat-shrink tubing during the irradiation process, contribute to the difference in tear performance between the two materials. Furthermore, the glass transition temperature (Tg) and melting point of ethylene-acrylate copolymers are lower than those of fluororesin-based materials, which also results in a lower shrinkage temperature for easy-to-peel ethylene-acrylate copolymer heat-shrink tubing compared to fluororesin-based materials.

[0102] In some embodiments, the lowest shrinkage temperature of the easy-to-peel heat shrink tubing can reach 70° C., and complete shrinkage can be achieved at 110° C., and the shrinkage temperature is low.

[0103] In some embodiments, the easily peelable heat shrinkable tube has a shrinkage ratio of 1.3-4.5 at a temperature of 110° C.

[0104] Thus, the easy-to-peel heat shrink tubing provided by this application has a low shrinkage temperature and a high shrinkage rate, making it suitable for assisting the shrinkage of large-ratio non-shrinkable polymer tubing. In addition, the addition of a reinforcing agent can also increase the tensile strength of the easy-to-peel heat shrink tubing.

[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] Test according to UL 224-2021, method 5.4.

[0117] Determination of complete shrinkage temperature

[0118] Take a 100mm sample and heat it in a programmed temperature oven. Set 50°C as the starting shrinkage temperature and increase the oven temperature by 10°C every 3 minutes so that the sample shrinks for 3 minutes at each temperature. Record the shrinkage temperature until the inner diameter does not change after 3 consecutive measurements. The temperature recorded for the first of the 3 consecutive times is the complete shrinkage temperature.

[0119] Determination of shrinkage

[0120] Take a 100mm sample and shrink it at 200°C for 3 minutes. Measure the inner diameter of the sample before and after shrinkage. Calculate the shrinkage using the following formula: Shrinkage = (Inner diameter before shrinkage - Inner diameter after shrinkage) / Inner diameter before shrinkage × 100%.

[0121] Example 1-1

[0122] Masterbatch processing

[0123] 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.

[0124] Extruded pipes

[0125] 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 9.7, and the molecular chain orientation of the extruded tube was measured to be 50%. The resulting semi-finished casing had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0126] Irradiation cross-linking

[0127] The semi-finished sleeve is irradiated by an electron accelerator device at a irradiation dose of 200 KGy for irradiation cross-linking.

[0128] expansion pipe

[0129] The irradiated cross-linked tube was expanded twice by an expansion device at 130-260° C., and then cooled and shaped to obtain a heat shrink tube with an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0130] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0131] Example 1-2

[0132] Masterbatch processing

[0133] 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.

[0134] Extruded pipes

[0135] Semi-molding was performed in the same manner as in Example 1-1 except that the stretching ratio was controlled to 9.8.

[0136] Irradiation cross-linking

[0137] Irradiation was performed in the same manner as in Example 1-1.

[0138] expansion tube

[0139] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0140] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0141] Examples 1-3

[0142] Masterbatch processing

[0143] 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).

[0144] Extruded pipes

[0145] Semi-molding was performed in the same manner as in Example 1-1.

[0146] Irradiation cross-linking

[0147] Irradiation was performed in the same manner as in Example 1-1.

[0148] expansion tube

[0149] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0150] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 46%.

[0151] Examples 1-4

[0152] Masterbatch processing

[0153] 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.

[0154] Extruded pipes

[0155] Semi-molding was performed in the same manner as in Example 1-1 except that the stretching ratio was controlled to 9.9.

[0156] Irradiation cross-linking

[0157] Irradiation was performed in the same manner as in Example 1-1.

[0158] expansion tube

[0159] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0160] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0161] Examples 1-5

[0162] Masterbatch processing

[0163] The production was carried out in the same manner as in Example 1-1.

[0164] Extruded pipes

[0165] Semi-molding was carried out in the same manner as in Example 1-1, except that the stretching ratio was controlled to be 8.5 and the molecular chain orientation degree of the extruded pipe was measured to be 40%.

[0166] Irradiation cross-linking

[0167] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 180 KGy.

[0168] expansion tube

[0169] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0170] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 35%.

[0171] Examples 1-6

[0172] Masterbatch processing

[0173] The production was carried out in the same manner as in Example 1-1.

[0174] Extruded pipes

[0175] Semi-molding was carried out in the same manner as in Example 1-1, except that the stretching ratio was controlled to be 12.2 and the molecular chain orientation degree of the extruded pipe was measured to be 70%.

[0176] Irradiation cross-linking

[0177] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 150 KGy.

[0178] expansion tube

[0179] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0180] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 60%.

[0181] Examples 1-7

[0182] Masterbatch processing

[0183] The production was carried out in the same manner as in Example 1-1.

[0184] Extruded pipes

[0185] Semi-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%.

[0186] Irradiation cross-linking

[0187] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 160 KGy.

[0188] expansion tube

[0189] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0190] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 80%.

[0191] Examples 1-8

[0192] Masterbatch processing

[0193] The production was carried out in the same manner as in Example 1-1.

[0194] Extruded pipes

[0195] Semi-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%.

[0196] Irradiation cross-linking

[0197] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 180 KGy.

[0198] expansion tube

[0199] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0200] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 85%.

[0201] Examples 1-9

[0202] Masterbatch processing

[0203] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM AC 1218) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 0.1 was replaced with ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOY TM The same procedure as in Example 1-1 was carried out except that the mass ratio of the crosslinking agent (AC 1218) / the antioxidant (antioxidant 1010) / the sensitized crosslinking agent (FRD-301) was 60 / 0.1 / 0.1.

[0204] Extruded pipes

[0205] Semi-molding was performed in the same manner as in Example 1-1.

[0206] Irradiation cross-linking

[0207] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 100 KGy.

[0208] expansion tube

[0209] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0210] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 46%.

[0211] Examples 1-10

[0212] Masterbatch processing

[0213] The production was carried out in the same manner as in Example 1-1.

[0214] Extruded pipes

[0215] Semi-molding was performed in the same manner as in Example 1-1.

[0216] Irradiation cross-linking

[0217] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 100 KGy.

[0218] expansion tube

[0219] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0220] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 42%.

[0221] Examples 1-11

[0222] Masterbatch processing

[0223] The production was carried out in the same manner as in Example 1-1.

[0224] Extruded pipes

[0225] Semi-molding was performed in the same manner as in Example 1-1.

[0226] Irradiation cross-linking

[0227] The semi-finished casing was irradiated with cobalt 60 (Co) at a controlled irradiation dose of 300 KGy in the same manner as in Example 1-1.

[0228] expansion tube

[0229] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0230] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 47%.

[0231] Examples 1-12

[0232] Masterbatch processing

[0233] The production was carried out in the same manner as in Example 1-1.

[0234] Extruded pipes

[0235] Semi-molding was performed in the same manner as in Example 1-1.

[0236] Irradiation cross-linking

[0237] Irradiation was performed in the same manner as in Example 1-1.

[0238] expansion tube

[0239] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 1-1 to obtain a heat shrinkable tube with an inner diameter of 0.77 mm, an outer diameter of 1.13 mm, and a wall thickness of 0.18 mm.

[0240] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 35%, and the molecular chain orientation after complete shrinkage was 45%.

[0241] Examples 1-13

[0242] Masterbatch processing

[0243] The production was carried out in the same manner as in Example 1-1.

[0244] Extruded pipes

[0245] Semi-molding was performed in the same manner as in Example 1-1.

[0246] Irradiation cross-linking

[0247] Irradiation was performed in the same manner as in Example 1-1.

[0248] expansion tube

[0249] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 1-1 to obtain a heat shrinkable tube with an inner diameter of 2 mm, an outer diameter of 2.2 mm, and a wall thickness of 0.1 mm.

[0250] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 75%, and the molecular chain orientation after complete shrinkage was 45%.

[0251] Examples 1-14

[0252] Masterbatch processing

[0253] The production was carried out in the same manner as in Example 1-1.

[0254] Extruded pipes

[0255] 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 29.9, and the molecular chain orientation of the extruded tube was measured to be 80%. The resulting semi-finished casing had an inner diameter of 0.4mm, an outer diameter of 1.06mm, and a wall thickness of 0.33mm.

[0256] Irradiation cross-linking

[0257] Irradiation was performed in the same manner as in Example 1-1.

[0258] expansion tube

[0259] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 1-1 to obtain a heat shrinkable tube with an inner diameter of 1.2 mm, an outer diameter of 1.6 mm, and a wall thickness of 0.2 mm.

[0260] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 70%.

[0261] Examples 1-15

[0262] Masterbatch processing

[0263] The production was carried out in the same manner as in Example 1-1.

[0264] Extruded pipes

[0265] 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 55.6, and the molecular chain orientation of the extruded tube was measured to be 80%. The semi-finished casing had an inner diameter of 3.0mm, an outer diameter of 4.04mm, and a wall thickness of 0.52mm.

[0266] Irradiation cross-linking

[0267] Irradiation was performed in the same manner as in Example 1-1.

[0268] expansion tube

[0269] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 1-1 to obtain a heat shrinkable tube with an inner diameter of 6.4 mm, an outer diameter of 7.0 mm, and a wall thickness of 0.3 mm.

[0270] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 70%.

[0271] Comparative Example 1-1

[0272] Masterbatch processing

[0273] 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.

[0274] Extruded pipes

[0275] 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 semi-finished casing had an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0276] Irradiation cross-linking

[0277] The semi-finished sleeve is irradiated by an electron accelerator device at a irradiation dose of 200 KGy for irradiation cross-linking.

[0278] expansion pipe

[0279] The irradiated cross-linked tube was expanded by filling nitrogen into an expansion device at 130-260°C. The tube was then cooled and shaped to obtain a heat shrink tube with an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0280] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 120°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0281] Comparative Example 1-2

[0282] Masterbatch processing

[0283] The same production as in Comparative Example 1-1 was carried out except that the low-density polyethylene (LDPE) was replaced with ethylene-vinyl acetate copolymer (EVA, 7350M).

[0284] Extruded pipes

[0285] Semi-molding was carried out in the same manner as in Comparative Example 1-1 except that the stretching ratio was controlled to be 10.2.

[0286] Irradiation cross-linking

[0287] Irradiation was performed in the same manner as in Comparative Example 1-1 except that the irradiation dose was controlled to 200 KGy.

[0288] expansion pipe

[0289] The expansion molding was performed in the same manner as in Comparative Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0290] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0291] Comparative Examples 1-3

[0292] Masterbatch processing

[0293] In addition to replacing low-density polyethylene (LDPE) with polyolefin elastomers (POE, ENGAGE TM 8180), the same method as Comparative Example 1-1 was used for production.

[0294] Extruded pipes

[0295] Semi-molding was carried out in the same manner as in Comparative Example 1-1 except that the stretching ratio was controlled to be 10.9.

[0296] Irradiation cross-linking

[0297] Irradiation was performed in the same manner as in Comparative Example 1-1 except that the irradiation dose was controlled to 200 KGy.

[0298] expansion pipe

[0299] The expansion molding was performed in the same manner as in Comparative Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0300] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 100°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 42%.

[0301] Comparative Examples 1-4

[0302] Masterbatch processing

[0303] The production was carried out in the same manner as in Example 1-1.

[0304] Extruded pipes

[0305] Semi-molding was carried out in the same manner as in Example 1-1, 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%.

[0306] Irradiation cross-linking

[0307] Irradiation was performed in the same manner as in Example 1-1.

[0308] expansion pipe

[0309] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0310] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 13%.

[0311] Comparative Examples 1-5

[0312] Masterbatch processing

[0313] The production was carried out in the same manner as in Example 1-1.

[0314] Extruded pipes

[0315] Semi-molding was carried out in the same manner as in Comparative Example 1-1 except that the stretching ratio was controlled to be 10.5.

[0316] Irradiation cross-linking

[0317] Irradiation was performed in the same manner as in Example 1-1 except that the irradiation dose was controlled to 50 KGy.

[0318] expansion pipe

[0319] The expansion molding was performed in the same manner as in Example 1-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0320] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 16%.

[0321] Comparative Examples 1-6

[0322] The commercially available tearable FEP heat shrink tubing was used, with a shrinkage ratio of 37.5%, an inner diameter of 1.12 mm before shrinkage, and an inner diameter of 0.7 mm after shrinkage.

[0323] For the heat shrink tubing prepared above, the preparation condition parameters for Examples 1-1 to 1-15 are shown in Table 1-1, and the preparation condition parameters for Comparative Examples 1-1 to 1-6 are shown in Table 1-2. The orientation degree of the molecular chain of the extruded tubing during extrusion was measured according to the above-mentioned orientation determination method, and the orientation degree of the molecular chain of the heat shrink tubing after complete shrinkage was measured; the tear linearity was measured according to the above-mentioned tear linearity test method; the tear strength was measured according to the above-mentioned tear strength test method; the complete shrinkage temperature was measured according to the above-mentioned complete shrinkage temperature determination method; and the shrinkage rate was measured according to the above-mentioned shrinkage rate determination method. The measurement results of Examples 1-1 to 1-15 and Comparative Examples 1-1 to 1-6 are shown in Table 1-3.

[0324] Table 1-1 Preparation condition parameters of Examples 1-1 to 1-15

[0325] Table 1-2 Preparation Condition Parameters of Comparative Examples 1-1 to 1-6

[0326] Table 1-3 Measurement results of Examples 1-1 to 1-15 and Comparative Examples 1-1 to 1-6

[0327] As can be seen from Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-3, the easy-to-peel heat-shrink tubing made from polyolefin and its copolymer resins is significantly affected by the type of polymer. EMA, EEA, EBA, and EMMA can all be used to prepare easy-to-peel heat-shrink tubing, demonstrating that these types of ethylene-acrylic acid copolymers can all be used to prepare easy-to-peel heat-shrink tubing. As can be seen from Examples 1-1, 1-5 to 1-8, 1-14 to 1-15, and Comparative Example 1-4, in addition to the type of polymer, the molecular chain orientation of the extruded tubing must be controlled to within a range of 40%-95% during the extrusion process. Furthermore, as can be seen from Examples 1-9 to 1-11 and Comparative Example 1-5, the irradiation dose must be controlled to achieve an appropriate degree of crosslinking, ultimately resulting in an easy-to-peel heat-shrink tubing with a molecular chain orientation of 30%-85% and linear tear resistance. It can be seen from Examples 1-1 to 1-15 and Comparative Example 1-6 that the easily peelable heat shrinkable tube provided by the present application has a lower shrinkage temperature and a higher shrinkage rate than the FEP heat shrinkable tube, and is suitable for assisting the shrinkage of large-ratio non-shrinkable polymer tubes.

[0328] Example 2-1

[0329] Masterbatch processing

[0330] 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, 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 and water-cooled and pelletized to form masterbatch pellets.

[0331] Extruded pipes

[0332] 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 (zone 1: 130°C, zone 2: 180°C, zone 3: 190°C, flange zone: 190°C, die zone: 190°C), with a draw ratio of 9.9. The extruded tube had a molecular chain orientation of 50%, resulting in a semi-finished casing with an inner diameter of 0.5mm, an outer diameter of 0.9mm, and a wall thickness of 0.2mm.

[0333] Irradiation cross-linking

[0334] The semi-finished sleeve is irradiated by an electron accelerator device at a irradiation dose of 200 KGy for irradiation cross-linking.

[0335] expansion pipe

[0336] The irradiated cross-linked tube was expanded twice by an expansion device at 130-260° C., and then cooled and shaped to obtain a heat shrink tube with an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0337] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0338] Example 2-2

[0339] Masterbatch processing

[0340] 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-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.

[0341] Extruded pipes

[0342] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.1.

[0343] Irradiation cross-linking

[0344] Irradiation was performed in the same manner as in Example 2-1.

[0345] expansion pipe

[0346] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0347] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0348] Example 2-3

[0349] Masterbatch processing

[0350] 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-butyl acrylate copolymer (EBA, AC 3717) / low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1. The same method as in Example 2-1 was used for production.

[0351] Extruded pipes

[0352] Semi-molding was performed in the same manner as in Example 2-1.

[0353] Irradiation cross-linking

[0354] Irradiation was performed in the same manner as in Example 2-1.

[0355] expansion pipe

[0356] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0357] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0358] Examples 2-4

[0359] Masterbatch processing

[0360] 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 methacrylate copolymer (EMMA, Sumitomo CM8014) / low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 60 / 10 / 0.1. The same method as in Example 2-1 was used for the production.

[0361] Extruded pipes

[0362] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.3.

[0363] Irradiation cross-linking

[0364] Irradiation was performed in the same manner as in Example 2-1.

[0365] expansion pipe

[0366] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0367] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0368] Examples 2-5

[0369] Masterbatch processing

[0370] In addition to ethylene-methyl acrylate copolymer (EMA, DuPont ELVALOYTM 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.

[0371] Extruded pipes

[0372] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0373] Irradiation cross-linking

[0374] Irradiation was performed in the same manner as in Example 2-1.

[0375] expansion pipe

[0376] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0377] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 120°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0378] Examples 2-6

[0379] Masterbatch processing

[0380] 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 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.

[0381] Extruded pipes

[0382] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0383] Irradiation cross-linking

[0384] Irradiation was performed in the same manner as in Example 2-1.

[0385] expansion pipe

[0386] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0387] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 130°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0388] Examples 2-7

[0389] Masterbatch processing

[0390] 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.

[0391] Extruded pipes

[0392] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.5.

[0393] Irradiation cross-linking

[0394] Irradiation was performed in the same manner as in Example 2-1.

[0395] expansion pipe

[0396] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0397] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 140°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0398] Examples 2-8

[0399] Masterbatch processing

[0400] 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.

[0401] Extruded pipes

[0402] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.6.

[0403] Irradiation cross-linking

[0404] Irradiation was performed in the same manner as in Example 2-1.

[0405] expansion pipe

[0406] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0407] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0408] Examples 2-9

[0409] Masterbatch processing

[0410] 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 AC 1218) / ethylene-vinyl acetate copolymer (EVA, 7350M) / antioxidant (antioxidant 1010) was 60 / 10 / 0.1.

[0411] Extruded pipes

[0412] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.6.

[0413] Irradiation cross-linking

[0414] Irradiation was performed in the same manner as in Example 2-1.

[0415] expansion pipe

[0416] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0417] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0418] Example 2-10

[0419] Masterbatch processing

[0420] 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 20 / 10 / 0.1.

[0421] Extruded pipes

[0422] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.5.

[0423] Irradiation cross-linking

[0424] Irradiation was performed in the same manner as in Example 2-1.

[0425] expansion pipe

[0426] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0427] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0428] Example 2-11

[0429] Masterbatch processing

[0430] 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 75 / 10 / 0.1.

[0431] Extruded pipes

[0432] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.8.

[0433] Irradiation cross-linking

[0434] Irradiation was performed in the same manner as in Example 2-1.

[0435] expansion pipe

[0436] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0437] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0438] Example 2-12

[0439] Masterbatch processing

[0440] 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 procedure as in Example 2-1 was carried out except that the mass ratio of the antioxidant (Antioxidant 1010) was 90 / 10 / 0.1.

[0441] Extruded pipes

[0442] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 9.7.

[0443] Irradiation cross-linking

[0444] Irradiation was performed in the same manner as in Example 2-1.

[0445] expansion pipe

[0446] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0447] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0448] Example 2-13

[0449] Masterbatch processing

[0450] 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 / 40 / 0.1.

[0451] Extruded pipes

[0452] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.6.

[0453] Irradiation cross-linking

[0454] Irradiation was performed in the same manner as in Example 2-1.

[0455] expansion pipe

[0456] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0457] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0458] Examples 2-14

[0459] Masterbatch processing

[0460] 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 / 60 / 0.1.

[0461] Extruded pipes

[0462] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.7.

[0463] Irradiation cross-linking

[0464] Irradiation was performed in the same manner as in Example 2-1.

[0465] expansion pipe

[0466] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0467] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 44%.

[0468] Example 2-15

[0469] Masterbatch processing

[0470] 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 same procedure as in Example 2-1 was carried out except that the mass ratio of the antioxidant (Antioxidant 1010) was 60 / 80 / 0.1.

[0471] Extruded pipes

[0472] Semi-molding was performed in the same manner as in Example 2-1 except that the stretching ratio was controlled to 10.8.

[0473] Irradiation cross-linking

[0474] Irradiation was performed in the same manner as in Example 2-1.

[0475] expansion pipe

[0476] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0477] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0478] Example 2-16

[0479] Masterbatch processing

[0480] The production was carried out in the same manner as in Example 2-1.

[0481] Extruded pipes

[0482] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 8.9 and the molecular chain orientation degree of the extruded pipe was measured to be 40%.

[0483] Irradiation cross-linking

[0484] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was changed to 190 KGy.

[0485] expansion pipe

[0486] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0487] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 35%.

[0488] Example 2-17

[0489] Masterbatch processing

[0490] The production was carried out in the same manner as in Example 2-1.

[0491] Extruded pipes

[0492] The molding was carried out in the same manner as in Example 2-1 except that the stretching ratio was controlled to be 12.6 and the molecular chain orientation degree of the extruded pipe was measured to be 70%.

[0493] Irradiation cross-linking

[0494] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was changed to 160 KGy.

[0495] expansion pipe

[0496] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0497] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 64%.

[0498] Example 2-18

[0499] Masterbatch processing

[0500] The production was carried out in the same manner as in Example 2-1.

[0501] Extruded pipes

[0502] 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%.

[0503] Irradiation cross-linking

[0504] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was changed to 170 KGy.

[0505] expansion pipe

[0506] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0507] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 82%.

[0508] Example 2-19

[0509] Masterbatch processing

[0510] The production was carried out in the same manner as in Example 2-1.

[0511] Extruded pipes

[0512] 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%.

[0513] Irradiation cross-linking

[0514] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was changed to 190 KGy.

[0515] expansion pipe

[0516] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0517] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 85%.

[0518] Example 2-20

[0519] Masterbatch processing

[0520] The production was carried out in the same manner as in Example 2-1.

[0521] Extruded pipes

[0522] Semi-molding was performed in the same manner as in Example 2-1.

[0523] Irradiation cross-linking

[0524] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was controlled to 100 KGy.

[0525] expansion pipe

[0526] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0527] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 40%.

[0528] Example 2-21

[0529] Masterbatch processing

[0530] The production was carried out in the same manner as in Example 2-1.

[0531] Extruded pipes

[0532] Semi-molding was performed in the same manner as in Example 2-1.

[0533] Irradiation cross-linking

[0534] The semi-finished casing was irradiated with cobalt 60 (Co) at a controlled irradiation dose of 300 KGy in the same manner as in Example 2-1.

[0535] expansion pipe

[0536] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0537] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 47%.

[0538] Example 2-22

[0539] Masterbatch processing

[0540] The production was carried out in the same manner as in Example 2-1.

[0541] Extruded pipes

[0542] Semi-molding was performed in the same manner as in Example 2-1.

[0543] Irradiation cross-linking

[0544] Irradiation was performed in the same manner as in Example 2-1.

[0545] expansion pipe

[0546] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 2-1 to obtain a heat shrinkable tube with an inner diameter of 0.77 mm, an outer diameter of 1.13 mm, and a wall thickness of 0.18 mm.

[0547] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 35%, and the molecular chain orientation after complete shrinkage was 44%.

[0548] Example 2-23

[0549] Masterbatch processing

[0550] The production was carried out in the same manner as in Example 2-1.

[0551] Extruded pipes

[0552] Semi-molding was performed in the same manner as in Example 2-1.

[0553] Irradiation cross-linking

[0554] Irradiation was performed in the same manner as in Example 2-1.

[0555] expansion pipe

[0556] The pressure of nitrogen gas charged into the expansion device and the size of the mold were changed, and expansion was carried out in the same manner as in Example 2-1 to obtain a heat shrinkable tube with an inner diameter of 2 mm, an outer diameter of 2.2 mm, and a wall thickness of 0.1 mm.

[0557] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 75%, and the molecular chain orientation after complete shrinkage was 44%.

[0558] Comparative Example 2-1

[0559] Masterbatch processing

[0560] 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 includes 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.), and then stretched into strands and water-cooled pelletized to form masterbatch pellets.

[0561] Extruded pipes

[0562] 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.

[0563] Irradiation cross-linking

[0564] The semi-finished sleeve is irradiated by an electron accelerator device at a irradiation dose of 200 KGy for irradiation cross-linking.

[0565] expansion pipe

[0566] The irradiated cross-linked tube was expanded by filling nitrogen into an expansion device at 130-260°C. The tube was then cooled and shaped to obtain a heat shrink tube with an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0567] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 120°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 43%.

[0568] Comparative Example 2-2

[0569] Masterbatch processing

[0570] 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.

[0571] Extruded pipes

[0572] Molding was carried out in the same manner as in Comparative Example 2-1 except that the stretching ratio was controlled to be 10.9.

[0573] Irradiation cross-linking

[0574] Irradiation was performed in the same manner as in Comparative Example 2-1.

[0575] expansion pipe

[0576] The expansion molding was performed in the same manner as in Comparative Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0577] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 100°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0578] Comparative Examples 2-3

[0579] Masterbatch processing

[0580] The same method as Comparative Example 2-1 was used to manufacture the product except that the low-density polyethylene (LDPE, LyondellBasell Lupolen 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.

[0581] Extruded pipes

[0582] Molding was carried out in the same manner as in Comparative Example 2-1 except that the stretching ratio was controlled to be 10.2.

[0583] Irradiation cross-linking

[0584] Irradiation was performed in the same manner as in Comparative Example 2-1.

[0585] expansion pipe

[0586] The expansion molding was performed in the same manner as in Comparative Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0587] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 45%.

[0588] Comparative Examples 2-4

[0589] Masterbatch processing

[0590] The production was carried out in the same manner as in Example 2-1.

[0591] Extruded pipes

[0592] 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%.

[0593] Irradiation cross-linking

[0594] Irradiation was performed in the same manner as in Example 2-1.

[0595] expansion pipe

[0596] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0597] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 10%.

[0598] Comparative Examples 2-5

[0599] Masterbatch processing

[0600] The production was carried out in the same manner as in Example 2-1.

[0601] Extruded pipes

[0602] The same production as in Example 2-1 was carried out except that the stretching ratio was controlled to 10.5.

[0603] Irradiation cross-linking

[0604] Irradiation was performed in the same manner as in Example 2-1 except that the irradiation dose was controlled to 50 KGy.

[0605] expansion pipe

[0606] The expansion molding was performed in the same manner as in Example 2-1 to obtain a heat shrinkable tube having an inner diameter of 1.0 mm, an outer diameter of 1.3 mm, and a wall thickness of 0.15 mm.

[0607] The heat shrink tubing was tested, and the results were as follows: the complete shrinkage temperature was 110°C, the shrinkage rate was 50%, and the molecular chain orientation after complete shrinkage was 20%.

[0608] Comparative Examples 2-6

[0609] The commercially available tearable FEP heat shrink tubing was used, with a shrinkage ratio of 37.5%, an inner diameter of 1.12 mm before shrinkage, and an inner diameter of 0.7 mm after shrinkage.

[0610] For the easily peelable heat shrinkable tubes prepared above, the preparation condition parameters for Example 1-1 and Examples 2-1 to 2-23 are shown in Table 2-1, and the preparation condition parameters for Comparative Examples 2-1 to 2-6 are shown in Table 2-2. The molecular chain orientation of the extruded tube was determined according to the above-mentioned orientation determination method, and the molecular chain orientation of the prepared heat shrinkable tube after complete shrinkage was determined; the tear linearity was measured according to the above-mentioned tear linearity test method; the tear strength was measured according to the above-mentioned tear strength test method; the tensile strength was measured according to the above-mentioned tensile strength test method; the complete shrinkage temperature was measured according to the above-mentioned complete shrinkage temperature determination method; and the shrinkage rate was measured according to the above-mentioned shrinkage rate determination method. The measurement results of Example 1-1, Examples 2-1 to 2-23, and Comparative Examples 2-1 to 2-6 are shown in Table 2-3.

[0611] Table 2-1 Preparation condition parameters of Example 1-1 and Examples 2-1 to 2-23

[0612] Table 2-2 Preparation condition parameters of comparative examples 2-1 to 2-6

[0613] Table 2-3 Measurement results of Example 1-1, Examples 2-1 to 2-23, and Comparative Examples 2-1 to 2-6

[0614] As can be seen from Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3, the easy-to-peel heat shrink tubing made from polyolefin and its copolymer resins is highly dependent on the type of polymer. EMA, EEA, EBA, and EMMA can all be used to prepare easy-to-peel heat shrink tubing, demonstrating that these types of ethylene-acrylic acid copolymers can all be used to prepare easy-to-peel heat shrink tubing. Examples 2-1, 2-16 to 2-19, and Comparative Example 2-4 demonstrate that, in addition to the type of polymer, the degree of orientation during the extrusion process must be controlled to within a range of 40%-95%. Furthermore, Examples 2-1, 2-20 to 2-21, and Comparative Example 2-5 demonstrate that the irradiation dose must be controlled to achieve an appropriate degree of crosslinking, ultimately resulting in an easy-to-peel heat shrink tubing with an orientation of 30%-85% and linear tear resistance. As can be seen from Examples 2-1 and 1-1, the addition of a reinforcing agent can increase the tensile strength of the easy-to-peel heat shrink tubing. It can be seen from Examples 2-1 to 2-23 and Comparative Example 2-6 that the easily peelable heat shrinkable tube provided by the present application has a lower shrinkage temperature and a higher shrinkage rate than the FEP heat shrinkable tube, and is suitable for assisting the shrinkage of large-ratio non-shrinkable polymer tubes.

[0615] The present application provides an easy-to-peel heat shrink tube made of polyolefin and its copolymer resin and reinforcing agent. Its tear strength is lower than that of FEP easy-to-peel heat shrink tube, its shrinkage temperature is low, its shrinkage rate is high, its tensile strength is high, and there is no adhesion with the internal material. It can completely replace FEP easy-to-peel heat shrink tube and provide a new option for easy-to-peel heat shrink tube.

[0616] 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 heat shrinkable tube having linear tearability in the longitudinal direction of the tube, characterized in that, The materials for preparing the easily peelable heat shrinkable tube include ethylene-acrylate copolymer as the matrix resin. In the extrusion process, the molecular chain orientation degree of the extruded tube is controlled to be 40%-95%. The shrinkage rate of the easily peelable heat shrinkable tube when heated at 200°C is more than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 30%-85%.

2. The easily peelable heat shrinkable tube according to claim 1, wherein In the extrusion process, the molecular chain orientation degree of the extruded tube is controlled to be 50%-90%. The shrinkage rate of the easily peelable heat shrinkable tube when heated at 200°C is more than 35%. After shrinking by more than 35% at 200°C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 40%-85%.

3. The peelable heat shrinkable tube according to any one of claims 1 to 2, characterized in that, After the extrusion process, an irradiation process is further included. The irradiation dose provided by the irradiation equipment in the irradiation process is 100-300 kGy.

4. The peelable heat shrinkable tube according to any one of claims 1 to 3, 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.

5. The peelable heat-shrinkable tube according to any one of claims 1 to 4, characterized in that, 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%; 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.

6. The easily peelable heat shrinkable tube according to any one of claims 1 to 5, characterized in that, Calculated by weight, the materials for preparing the easily peelable heat shrinkable tube include the following components: Ethylene-acrylate copolymer: 20-90 parts; Reinforcing agent: 10-80 parts.

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

8. The peelable heat shrinkable tube according to claim 7, wherein, The polyethylene is low-density polyethylene, and the low-density polyethylene satisfies: the melt index is (0.3-7) g / 10 min 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 / 10 min 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 / 10 min 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 / 10 min and the tensile strength is 28-40 Mpa; and / or, The melt index is (0.5-5) g / 10 min, 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 / 10 min, the tensile strength is 16-25 Mpa, and the vinyl acetate content does not exceed 20%.

9. The peelable heat shrinkable tube according to any one of claims 1 to 8, characterized in that, Calculated by weight, the materials for preparing the easily peelable heat shrinkable tube further include 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 an asymmetric hindered phenol antioxidant, an aromatic amine antioxidant, a thioether antioxidant, and a phosphite antioxidant; The lubricant includes at least one of FEP powder, zinc stearate, magnesium stearate, silicone, calcium stearate, or ethylene bisstearamide.

10. The peelable heat shrinkable tube according to any one of claims 1 to 9, characterized in that, It means that the ratio representing the tear linearity is in the range of 50%:50% to 48%:52%; and / or, The inner diameter of the easily peelable heat shrinkable tube is 0.3 - 16 mm; and / or, The wall thickness of the easily peelable heat shrinkable tube is 0.1 - 2 mm.

11. An easily peelable heat shrinkable tube having linear tearability in the longitudinal direction of the tube, characterized in that, The preparation material of the easily peelable heat shrinkable tube contains an ethylene-acrylate copolymer as the matrix resin. When the easily peelable heat shrinkable tube is heated at 200 °C, the shrinkage rate is more than 35%. After shrinking by more than 35% at 200 °C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 30% - 85%.

12. The easily peelable heat shrinkable tube according to claim 11, wherein, When the easily peelable heat shrinkable tube is heated at 200 °C, the shrinkage rate is more than 35%. After shrinking by more than 35% at 200 °C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 35% - 85%.

13. The easily peelable heat shrinkable tube according to claim 11, characterized in that, When the easily peelable heat shrinkable tube is heated at 200 °C, the shrinkage rate is more than 35%. After shrinking by more than 35% at 200 °C, the molecular chain orientation degree of the easily peelable heat shrinkable tube is 40% - 85%.

14. A method for preparing the easily peelable heat-shrinkable tube 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. The raw materials include an ethylene-acrylate copolymer; Extrusion into a tube: Extrude the masterbatch particles obtained above through an extruder to obtain a semi-finished tube. Among them, control the molecular chain orientation degree of the extruded tube to be 40% - 95%; Irradiation process: Irradiate the above semi-finished tube through an irradiation device, and control the irradiation dose to be 100 - 300 KGy to obtain an irradiated tube; Expansion molding: Expand the above irradiated tube at 130 - 260 °C, and then cool and shape it to obtain an easily peelable heat shrinkable tube; among them, after the easily peelable heat shrinkable tube shrinks by more than 35% at 200 °C, the molecular chain orientation degree is 30% - 85%.

15. The preparation method according to claim 14, wherein, 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 a tube step, the molecular chain orientation degree of the extruded tube is 50% - 90%; and / or, In the expansion molding step, cool and shape it to obtain an easily peelable heat shrinkable tube. Among them, after the easily peelable heat shrinkable tube shrinks by more than 35% at 200 °C, the molecular chain orientation degree is 40% - 85%.

16. The preparation method according to claim 14, characterized in that, In the masterbatch processing step and the extrusion into a tube step, the extrusion temperature of the extruder is 130 - 190 °C; and / or, In the extrusion into a tube step, the draw ratio of the extruded tube is 7 - 60; and / or, In the extrusion into a tube step, the draw ratio of the extruded tube is 8.5 - 30.

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