High-frequency and high-pressure resistant heat shrink tube and preparation method thereof

Abstract

The invention discloses a high-frequency and high-voltage resistant heat shrink tube, which adopts polyethylene as a main body resin, is a non-polar material, has a dipole moment of 0 and a very low dielectric loss of 10 <-4 >, and can realize higher-voltage thermal breakdown under high frequency due to the relatively low dielectric loss. Meanwhile, the insulating heat conduction material with low dielectric loss and high heat conductivity coefficient is selected, and when the polyethylene material generates heat at high frequency, the heat shrink tube has good heat conductivity coefficient and small temperature rise, so that the voltage of heat breakdown resistance of the heat shrink tube can be further improved. According to the high-frequency and high-voltage resistant heat shrink tube, the leakage current does not exceed 100 mA after the high-frequency and high-voltage resistant heat shrink tube is resistant to the voltage of 5000 V at the frequency of 400 + / -100 kHz for 60 s, and the safety requirement of the national standard GB9706.202-2021 is met.

Description

Technical Field

[0001] The present invention relates to the technical field of heat shrinkable tubes, and particularly relates to a high-frequency and high-voltage resistant heat shrinkable tube and a preparation method thereof. Background Art

[0002] Heat shrinkable tubes are widely used in the insulation protection of various wire harnesses, solder joints, and inductors, the rust prevention and corrosion prevention of metal pipes and rods, the auxiliary production of medical catheters, etc. They generally work in a power frequency (50Hz) voltage environment, and the breakdown voltage of heat shrinkable tubes can range from dozens of kilovolts to hundreds of kilovolts. However, in a high-frequency (400±100kHz) and high-voltage environment, the voltage withstand strength and voltage withstand time of heat shrinkable tubes will seriously decline, which will seriously affect the equipment life and the safety of personnel during use. Especially in the medical field, the requirements for the use of high-frequency and high-voltage resistant heat shrinkable tubes are more stringent.

[0003] A high-frequency electrosurgical unit (high-frequency surgical instrument) is an electrosurgical device that replaces a mechanical scalpel for tissue cutting. It heats the tissue by generating a high-frequency and high-voltage current at the effective electrode tip when it comes into contact with the body, achieving the separation and coagulation of body tissues, thereby serving the purpose of cutting and hemostasis. Currently, the generally adopted frequency of electrosurgical units is about 300 - 750kHz. If the frequency is too high, it is easy to cause electrostatic induction of parasitic capacitance and increase the possibility of current flowing to areas other than the incision; while if the frequency is too low (such as ≤300kHz), a dangerous Faraday effect will occur, that is, the excitatory effect on organisms will be enhanced, resulting in muscle spasms and pain, and in severe cases, ventricular fibrillation. After the high-frequency electric field is excited, due to the dielectric loss of the raw materials used for preparing the heat shrinkable tube and the reasons of the raw materials themselves, the heat shrinkable tube generates heat in the electric field under the action of the changing electric field, resulting in an increase in the temperature of the heat shrinkable tube. Especially in the case of a high-voltage electric field, due to more heat generated by dielectric loss, it cannot be dissipated in a short time. The accumulation of heat causes the temperature of the polymer to rise, resulting in a sharp increase in the conductance of the polymer according to an exponential law. The conductance loss generates more heat, further increasing the temperature. The temperature of the heat shrinkable tube rises sharply, leading to oxidation, melting, and coking of the polymer, and eventually resulting in breakdown and ultimately product failure. Therefore, high requirements are imposed on the heat shrinkable tube sleeved on the high-frequency electrosurgical unit, requiring it to meet the high-frequency resistance performance, which can not only ensure the safe use of the high-frequency electrosurgical unit but also prevent the high-frequency electrosurgical unit from affecting other in-use electronic devices. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high-frequency and high-voltage resistant heat shrinkable tube made of polyethylene and an insulating and heat-conducting material, which, at a frequency of 400±100kHz and a voltage of 5000V, has a leakage current not exceeding 100mA after withstanding voltage for 60s, meeting the safety requirements of the national standard GB9706.202 - 2021.

[0005] To achieve the above object, the present invention provides a high-frequency and high-voltage resistant heat-shrinkable tube. Calculated by weight parts, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube include the following components:

[0006] Polyethylene: 30 - 50 parts;

[0007] Insulating and heat-conducting material: 25 - 50 parts.

[0008] In some embodiments of the present application, the tensile strength of the polyethylene is greater than 17 Mpa.

[0009] In some embodiments of the present application, the insulating and heat-conducting material includes at least one of α-Al2O3, boron nitride, and aluminum nitride.

[0010] In some embodiments of the present application, the average particle size of the insulating and heat-conducting material is 1 - 10 μm.

[0011] In some embodiments of the present application, the average particle size of the insulating and heat-conducting material is 4 - 7 μm.

[0012] In some embodiments of the present application, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube further include polyolefin elastomer: 5 - 10 parts, and the polyolefin elastomer includes at least one of thermoplastic elastomer polymerized by metallocene-catalyzed ethylene and α-olefin, ethylene propylene diene monomer (EPDM), and ethylene propylene copolymer (EPM).

[0013] In some embodiments of the present application, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube further include compatibilizer: 1 - 5 parts, and the compatibilizer includes at least one of polyolefin elastomer graft and polyethylene graft.

[0014] In some embodiments of the present application, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube further include antioxidant 0.3 - 0.5 parts, and the antioxidant includes at least one of hindered phenol main antioxidant and thioether antioxidant.

[0015] In some embodiments of the present application, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube further include coupling agent 0.3 - 1 part, and the coupling agent includes at least one of aluminate coupling agent and titanate coupling agent.

[0016] In some embodiments of the present application, the preparation materials of the high-frequency and high-voltage resistant heat-shrinkable tube further include sensitizer 0.3 - 1 part, and the sensitizer includes at least one of trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, triallyl isocyanate, or 1,3-butanediol dimethacrylate.

[0017] To achieve the above object, the present invention further provides a preparation method of a high-frequency and high-voltage resistant heat-shrinkable tube, including the following steps:

[0018] Masterbatch processing: Polyethylene and insulating and heat-conducting materials are kneaded in a kneader according to a ratio, and then extruded, drawn into strips, and pelletized by an extrusion device to obtain masterbatch pellets;

[0019] Extrusion into a tube: The masterbatch pellets obtained above are extruded by an extruder to obtain semi-finished pipe materials.

[0020] Irradiation process: The semi-finished pipe materials above are irradiated by an irradiation device to obtain irradiated pipe materials;

[0021] Expansion molding: The irradiated pipe materials above are expanded, cooled, and shaped to obtain the high-frequency and high-voltage resistant heat-shrinkable tube.

[0022] In some embodiments of the present application, in the masterbatch processing step, when the polyethylene and insulating and heat-conducting materials are kneaded, a polyolefin elastomer, a compatibilizer, an antioxidant, a coupling agent, or a sensitizer can also be added for kneading;

[0023] In some embodiments of the present application, in the masterbatch processing step, the kneading temperature of the kneader is 100 - 130 °C, and the kneading time is 10 - 20 min;

[0024] In some embodiments of the present application, in the masterbatch processing step, the extrusion temperature of the extrusion device is 130 - 190 °C;

[0025] In some embodiments of the present application, in the extrusion into a tube step, the extrusion temperature of the extruder is 130 - 190 °C;

[0026] In some embodiments of the present application, in the irradiation process step, the irradiation dose of the irradiation device is 60 - 200 kGy;

[0027] In some embodiments of the present application, in the expansion molding step, the expansion temperature during expansion is 130 - 260 °C, and the expansion ratio is 2 - 3 times.

[0028] Beneficial effects that the present invention can achieve:

[0029] The high-frequency and high-voltage resistant heat-shrinkable tube of the present invention uses polyethylene as the main resin. It is a non-polar material with a dipole moment of 0 and a very low dielectric loss of 10 -4, a lower dielectric loss can achieve thermal breakdown at a higher voltage at high frequencies. At the same time, an insulating and heat-conducting material with a lower dielectric loss and a higher thermal conductivity is selected. When the polyethylene material generates heat at high frequencies, due to the good thermal conductivity of the heat shrinkable tube, its temperature rise is small, which can further improve its voltage resistance to thermal breakdown. The high-frequency and high-voltage resistant heat shrinkable tube provided by the present invention has a leakage current of no more than 100 mA after withstanding a voltage of 5000 V for 60 s at a frequency of 400 ± 100 kHz, meeting the safety requirements of the national standard GB9706.202-2021. Specific Embodiments

[0030] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In the present invention, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0033] The present invention provides a high-frequency voltage resistant heat shrinkable tube. Calculated by weight, the preparation materials of the high-frequency voltage resistant heat shrinkable tube include the following components:

[0034] Polyethylene: 30-50 parts;

[0035] Insulating and heat-conducting material: 25-50 parts;

[0036] The high-frequency and high-voltage resistant heat shrinkable tube has a leakage current of no more than 100 mA after withstanding a voltage of 5000 V for 60 s at a frequency of 400 ± 100 kHz.

[0037] A polymer is formed by connecting many atoms with covalent bonds, and the valence electrons are basically in a relatively stable low-energy state. Therefore, polymer materials are generally insulators, and the volume resistivity is as high as 10 8Therefore, it has a good withstand voltage level at power frequency, up to several hundred kV. However, at high frequencies, the withstand voltage of some polymer materials will drop significantly, which is mainly related to the polarity, dielectric loss, and frequency characteristics of the electric field of the polymer materials. Polymer materials are divided into non-polar, weakly polar, moderately polar, and strongly polar materials. From a microscopic structure perspective, polarity is mainly caused by the non-coincidence of the positive and negative charge centers in the molecule, that is, molecular polarity, and the magnitude of the dipole moment is commonly used to represent the magnitude of molecular polarity. When a polymer material is placed in an electric field, due to the existence of the dipole moment, the dipoles of its molecules are arranged along the direction of the electric field, resulting in the orientation of the molecules and being polarized by the electric field. Since the arrangement and rotation of polar molecules along the external electric field need to overcome their own inertia and rotational resistance, a part of the electrical energy is consumed and converted into heat energy. That is, dielectric loss. When the frequency is very low, all polarizations have sufficient time to fully follow the changes in the electric field, so the energy consumption is very low and the generated heat is less. However, when the frequency increases, polar polymer materials will consume a part of the electrical energy to overcome the internal friction resistance due to the rotation of dipoles under an alternating electric field, and the heat energy converted will increase significantly, that is, the dielectric loss will increase significantly. A large dielectric loss will cause the material to heat up, age, and even be damaged, resulting in breakdown at a lower voltage, that is, the so-called thermal breakdown.

[0038] The present invention uses polyethylene as the main resin, which is a non-polar material with a dipole moment of 0 and a very low dielectric loss of 10 -4 , and a lower dielectric loss can achieve a higher voltage thermal breakdown at high frequencies. At the same time, an insulating and heat-conducting material with a lower dielectric loss and a higher thermal conductivity is selected. When the polyethylene material generates heat at high frequencies, due to the good thermal conductivity of the heat shrinkable tube, its temperature rise is small, which can further improve its voltage resistance to thermal breakdown. At the same time, both polyethylene and the insulating and heat-conducting material have good insulation performance, and the high-voltage resistance performance under high-frequency conditions can be achieved.

[0039] Polyethylene is a thermoplastic plastic polymerized from ethylene. Due to the different densities of the resins obtained by different polymerization methods, it is divided into high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), and low-density polyethylene (LDPE).

[0040] In some embodiments of the present application, the tensile strength of polyethylene is greater than 17 Mpa, and the tensile strength within this range is beneficial to improving the tensile strength of the heat shrinkable tube.

[0041] In some embodiments of the present application, the insulating and heat-conducting material includes at least one of α-Al2O3, boron nitride, and aluminum nitride. These three insulating and heat-conducting materials have a lower dielectric loss and can achieve a higher voltage thermal breakdown at high frequencies.

[0042] In some embodiments of the present application, the average particle size of the insulating and heat-conducting material is 1 - 10 μm.

[0043] In some embodiments of the present application, the average particle size of the insulating and heat-conducting material is 4-7 μm. If the particle size is too large, it will affect its own withstand voltage performance and the withstand voltage performance will decrease. If the particle size is too small, the dispersibility is poor, which affects the fluidity and processing performance.

[0044] In some embodiments of the present application, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube further includes a polyolefin elastomer, and the polyolefin elastomer includes at least one of a thermoplastic elastomer polymerized from metallocene-catalyzed ethylene and α-olefin, ethylene propylene diene monomer (EPDM), and ethylene propylene copolymer (EPM). The addition of the polyolefin elastomer can improve the compatibility between polyethylene and the insulating and heat-conducting material, can improve the elongation at break of the heat-shrinkable tube, and thus improve its toughness and the mechanical properties of the heat-shrinkable tube.

[0045] In some embodiments of the present application, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube further includes a compatibilizer, and the compatibilizer includes at least one of a polyolefin elastomer graft and a polyethylene graft. The polyolefin elastomer graft includes a maleic anhydride graft of POE; the polyethylene graft includes a maleic anhydride graft. The compatibilizer can improve the bonding force between polyethylene and the insulating and heat-conducting material, can improve the tensile strength and elongation at break of the heat-shrinkable tube, and thus improve its tensile strength and toughness, and further improve the mechanical properties of the heat-shrinkable tube.

[0046] In some embodiments of the present application, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube further includes an antioxidant, and the antioxidant includes at least one of a hindered phenol main antioxidant and a thioether antioxidant. By adding the antioxidant, it is beneficial to improve the antioxidant performance and aging resistance of the heat-shrinkable tube and extend the service life of the heat-shrinkable tube.

[0047] In some embodiments of the present application, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube further includes a coupling agent, and the coupling agent includes at least one of an aluminate coupling agent and a titanate coupling agent. The coupling agent can improve the bonding force between polyethylene and the insulating and heat-conducting material, can improve the elongation at break of the heat-shrinkable tube, and thus improve its toughness and the mechanical properties of the heat-shrinkable tube.

[0048] In some embodiments of the present application, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube further includes a sensitizer, and the sensitizer includes at least one of trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, triallyl isocyanate, or 1,3-butanediol dimethacrylate. The addition of the sensitizer can improve the crosslinking degree of the irradiation process and reduce the irradiation dose.

[0049] In some embodiments, calculated by weight, the material for preparing the high-frequency and high-voltage resistant heat-shrinkable tube includes the following components:

[0050] Polyethylene: 30 - 50 parts, Insulating and heat-conducting material: 25 - 50 parts. For example, the polyethylene can be any weight part within the range of 30 - 50 parts such as 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.; the insulating and heat-conducting material can be any weight part within the range of 25 - 50 parts such as 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.

[0051] Under the limitation of the above weight parts, it is beneficial to promote the mixing between various raw materials, which not only meets the high-frequency and high-voltage resistance performance but also can achieve certain mechanical properties such as strength and toughness.

[0052] In some embodiments, calculated by weight parts, the preparation materials for the high-frequency and high-voltage resistant heat-shrinkable tube further include the following components:

[0053] Polyolefin elastomer: 5 - 10 parts; compatibilizer: 1 - 5 parts; antioxidant 0.3 - 0.5 parts; coupling agent 0.3 - 1 part; sensitizer 0.3 - 1 part. For example, the polyolefin elastomer can be any weight part within the range of 5 - 10 parts such as 5 parts, 7 parts, 10 parts, etc.; the compatibilizer can be any weight part within the range of 1 - 5 parts such as 1 part, 3 parts, 5 parts, etc.; the antioxidant can be any weight part within the range of 0.3 - 0.5 parts such as 0.3 parts, 0.4 parts, 0.5 parts, etc.; the coupling agent can be any weight part within the range of 0.3 - 1 part such as 0.3 parts, 0.5 parts, 0.8 parts, 1 part, etc.; the sensitizer can be any weight part within the range of 0.3 - 1 part such as 0.3 parts, 0.5 parts, 0.8 parts, 1 part, etc.

[0054] The addition of the above components can further improve the mechanical properties such as strength and toughness of the heat-shrinkable tube.

[0055] The present invention also provides a preparation method for a high-frequency and high-voltage resistant heat-shrinkable tube, including the following steps:

[0056] Masterbatch processing: Mix polyethylene and the insulating and heat-conducting material according to the ratio through a kneader, and then extrude, draw into strips, and pelletize through an extrusion device to obtain masterbatch particles;

[0057] Extrusion into a tube: Extrude the obtained masterbatch particles through an extruder to obtain a semi-finished tube.

[0058] Irradiation process: Irradiate the above semi-finished tube through an irradiation device to obtain an irradiated tube;

[0059] Expansion molding: Expand, cool, and shape the above irradiated tube to obtain the high-frequency and high-voltage resistant heat-shrinkable tube.

[0060] In some embodiments, in the masterbatch processing step, when polyethylene and the insulating and heat-conducting material are kneaded, a polyolefin elastomer, a compatibilizer, an antioxidant, a coupling agent, or a sensitizer can also be added for kneading.

[0061] In some embodiments, in the masterbatch processing step, the mixing temperature of the internal mixer is 100 - 130 °C, and the mixing time is 10 - 20 min.

[0062] In some embodiments, in the masterbatch processing step, the extrusion temperature of the extrusion equipment is 130 - 190 °C.

[0063] In some embodiments, in the extrusion into tube step, the extrusion temperature of the extruder is 130 - 190 °C.

[0064] In some embodiments, in the irradiation process step, the irradiation dose of the irradiation equipment is 60 - 200 kGy.

[0065] In some embodiments, in the expansion molding step, the expansion temperature during expansion is 130 - 260 °C, and the expansion ratio is 2 - 3 times.

[0066] The technical solutions of the present invention will be 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 invention and are not used to limit the present invention.

[0067] Measurement of high-frequency and high-voltage resistance

[0068] Testing is carried out using a medical high-frequency dielectric strength tester, model: CS9706TY, manufacturer: Changsheng Instrument Intelligent Technology (Hangzhou) Co., Ltd. The measurement of high-frequency and high-voltage resistance is carried out in accordance with the standard requirements of GB9706.202 - 2021. The passing standard for the measurement is: at a frequency of 400 ± 100 kHz, a voltage of 5000 V, and after withstanding voltage for 60 s, the leakage current does not exceed 100 mA.

[0069] Measurement of thermal conductivity

[0070] The measurement is carried out in accordance with the measurement method of ASTM D5470.

[0071] Measurement of mechanical properties

[0072] The tensile strength and elongation at break are measured in accordance with the measurement method of UL224.

[0073] Example 1

[0074] Masterbatch processing

[0075] Mix low density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4, add it to an internal mixer for internal mixing. The internal mixing temperature is 100 - 130 °C, and the internal mixing time is 15 min. Put the material obtained from the above process into a twin-screw extruder with a diameter of 30 mm, and extrude it at a screw speed of 45 rpm and a temperature of 130 - 190 °C, then draw the strip, cool it with water and cut it into pellets, finally forming masterbatch pellets.

[0076] Extrude pipes

[0077] Use the above-obtained masterbatch pellets to form pipes with a single-screw extruder. The screw used is a full-thread screw, and extrude at a screw speed of 5 - 45 rpm and a die temperature of 130 - 190 °C to obtain a semi-finished casing with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0078] Irradiation crosslinking

[0079] Irradiate the above semi-finished casing with an electron accelerator device at an irradiation dose of 150 kGy for irradiation crosslinking to obtain an irradiated crosslinked pipe.

[0080] Expand the pipe

[0081] Expand the above irradiated crosslinked pipe 2 times with an expansion device at 130 - 260 °C; then cool and shape it to obtain a high-frequency and high-voltage resistant heat shrinkable pipe with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0082] Example 2

[0083] Masterbatch processing

[0084] Except for changing low density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 to linear low density polyethylene (LLDPE, LLDPE 218W) / α-Al2O3 (4μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0085] Extrude pipes

[0086] Perform semi-forming in the same manner as in Example 1 to obtain a semi-finished casing with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0087] Irradiation crosslinking

[0088] Perform irradiation in the same manner as in Example 1.

[0089] Expanded pipe

[0090] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0091] Example 3

[0092] Masterbatch processing

[0093] Except that the low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was replaced with medium-density polyethylene (MDPE, DOW AXELERON TM 8864NT) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0094] Extruded pipe

[0095] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0096] Irradiation crosslinking

[0097] Irradiation was carried out in the same manner as in Example 1.

[0098] Expanded pipe

[0099] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0100] Example 4

[0101] Masterbatch processing

[0102] Except that the low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was replaced with high-density polyethylene (HDPE, lyondellbasell ACP6541A) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0103] Extruded pipe

[0104] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0105] Irradiation crosslinking

[0106] Irradiation was carried out in the same manner as in Example 1.

[0107] Expanding the pipe

[0108] Expansion forming, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0109] Example 5

[0110] Masterbatch processing

[0111] Manufacturing was carried out in the same manner as in Example 1, except that α-Al2O3 (4 μm) was replaced with α-Al2O3 (1 μm).

[0112] Extruding the pipe

[0113] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0114] Irradiation crosslinking

[0115] Irradiation was carried out in the same manner as in Example 1.

[0116] Expanding the pipe

[0117] Expansion forming, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0118] Example 6

[0119] Masterbatch processing

[0120] Manufacturing was carried out in the same manner as in Example 1, except that α-Al2O3 (4 μm) was replaced with α-Al2O3 (7 μm).

[0121] Extruding the pipe

[0122] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0123] Irradiation crosslinking

[0124] Irradiation was carried out in the same manner as in Example 1.

[0125] Expanding the pipe

[0126] Expansion molding, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0127] Example 7

[0128] Masterbatch processing

[0129] Manufacturing was carried out in the same manner as in Example 1, except that α-Al2O3 (4 μm) was replaced with α-Al2O3 (10 μm).

[0130] Extruding the pipe

[0131] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0132] Irradiation crosslinking

[0133] Irradiation was carried out in the same manner as in Example 1.

[0134] Expanding the pipe

[0135] Expansion molding, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0136] Example 8

[0137] Masterbatch processing

[0138] Manufacturing was carried out in the same manner as in Example 1, except that low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was replaced with low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / boron nitride (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4.

[0139] Extruding the pipe

[0140] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0141] Irradiation crosslinking

[0142] Irradiation was carried out in the same manner as in Example 1.

[0143] Expanding the pipe

[0144] Expansion molding, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0145] Example 9

[0146] Masterbatch processing

[0147] Manufacture was carried out in the same manner as in Example 1, except that low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was replaced with low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / aluminum nitride (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4.

[0148] Extruding pipes

[0149] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0150] Irradiation crosslinking

[0151] Irradiation was carried out in the same manner as in Example 1.

[0152] Expanding pipes

[0153] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0154] Example 10

[0155] Masterbatch processing

[0156] Manufacture was carried out in the same manner as in Example 1, except that low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was replaced with (mass ratio) = 30 / 35 / 0.4.

[0157] Extruding pipes

[0158] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0159] Irradiation crosslinking

[0160] Irradiation was carried out in the same manner as in Example 1.

[0161] Expanding pipes

[0162] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0163] Example 11

[0164] Masterbatch processing

[0165] Manufacture was carried out in the same manner as in Example 1, except that the ratio of low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was changed to (mass ratio) = 30 / 50 / 0.4.

[0166] Extruding pipes

[0167] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0168] Irradiation crosslinking

[0169] Irradiation was carried out in the same manner as in Example 1.

[0170] Expanding pipes

[0171] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0172] Example 12

[0173] Masterbatch processing

[0174] Manufacture was carried out in the same manner as in Example 1, except that the ratio of low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was changed to (mass ratio) = 40 / 25 / 0.4.

[0175] Extruding pipes

[0176] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0177] Irradiation crosslinking

[0178] Irradiation was carried out in the same manner as in Example 1.

[0179] Expanding pipes

[0180] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0181] Example 13

[0182] Masterbatch processing

[0183] Manufacture was carried out in the same manner as in Example 1, except that the ratio of low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was changed to (mass ratio) = 50 / 25 / 0.4.

[0184] Extrusion of pipes

[0185] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0186] Irradiation crosslinking

[0187] Irradiation was carried out in the same manner as in Example 1.

[0188] Expansion of pipes

[0189] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0190] Example 14

[0191] Masterbatch processing

[0192] Manufacture was carried out in the same manner as in Example 1, except that the ratio of low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 was changed to low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (4 μm) / metallocene-catalyzed ethylene and α-olefin copolymerized thermoplastic elastomer (POE, ENGAGE TM 8480) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 8 / 0.4.

[0193] Extrusion of pipes

[0194] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0195] Irradiation crosslinking

[0196] Irradiation was carried out in the same manner as in Example 1.

[0197] Expansion of pipes

[0198] Expansion molding, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0199] Example 15

[0200] Masterbatch processing

[0201] Except for replacing low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 with low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / ethylene propylene diene monomer (EPDM, NORDEL TM 6530) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 8 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0202] Extruding the pipe

[0203] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0204] Irradiation crosslinking

[0205] Irradiation was carried out in the same manner as in Example 1.

[0206] Expanding the pipe

[0207] Expansion molding, cooling, and shaping were carried out in the same manner as in Example 1 to obtain a high-frequency and high-voltage resistant heat-shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0208] Example 16

[0209] Masterbatch processing

[0210] Except for replacing low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 with low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / α-Al2O3 (4 μm) / ethylene propylene copolymer (EPM, Vistalon TM 785) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 8 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0211] Extruding the pipe

[0212] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished casing with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0213] Irradiation crosslinking

[0214] Irradiation was carried out in the same manner as in Example 1.

[0215] Expanding the pipe

[0216] Expansion forming, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a heat shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0217] Comparative Example 1

[0218] Masterbatch processing

[0219] Low-density polyethylene (LDPE, lyondellbasell Lupolen 2426K) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 0.4 was added to a kneader for kneading. The kneading temperature was 100 - 130 °C, and the kneading time was 15 min. The material obtained from 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 - 190 °C, followed by strand drawing, water cooling, and pelletizing to finally form masterbatch particles.

[0220] Extruding the pipe

[0221] The masterbatch particles obtained above were used to form a pipe by means of a single-screw extruder. A full-thread screw was used, and the pipe was extruded at a screw speed of 5 - 45 rpm and a die temperature of 130 - 190 °C to obtain a semi-finished casing with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0222] Irradiation crosslinking

[0223] The above semi-finished casing was irradiated using an electron accelerator device and irradiated with a dose of 150 kGy for crosslinking to obtain an irradiated crosslinked pipe.

[0224] Expanding the pipe

[0225] The above irradiated crosslinked pipe was expanded 2 times at 130 - 260 °C using an expansion device; then it was cooled and sized to obtain a heat shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0226] Comparative Example 2

[0227] Masterbatch processing

[0228] Except for changing the ratio of low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 to low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (20 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0229] Extruded pipe

[0230] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0231] Irradiation crosslinking

[0232] Irradiation was carried out in the same manner as in Example 1.

[0233] Expanded pipe

[0234] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a heat shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0235] Comparative Example 3

[0236] Masterbatch processing

[0237] Except for changing the ratio of low-density polyethylene (LDPE, LyondellBasell Lupolen 2426K) / α-Al2O3 (4 μm) / antioxidant (antioxidant 1010) (mass ratio) = 30 / 25 / 0.4 to (mass ratio) = 30 / 10 / 0.4, the manufacturing was carried out in the same manner as in Example 1.

[0238] Extruded pipe

[0239] Semi-forming was carried out in the same manner as in Example 1 to obtain a semi-finished sleeve with an inner diameter of 1.5 mm and a wall thickness of 0.4 mm.

[0240] Irradiation crosslinking

[0241] Irradiation was carried out in the same manner as in Example 1.

[0242] Expanded pipe

[0243] Expansion molding, cooling, and sizing were carried out in the same manner as in Example 1 to obtain a heat shrinkable tube with an inner diameter of 3.0 mm and a wall thickness of 0.24 mm.

[0244] Comparative Example 4

[0245] Use a commercially available PTFE heat shrinkable tube with the model number AWG10, and the manufacturer is ZEUS.

[0246] When the proportion of the insulating and heat-conducting material is too high, although the pipe can be extruded, in the subsequent expansion molding process, due to the too high proportion of the insulating and heat-conducting material, the physical properties such as the tensile strength and elongation at break of the extruded pipe decrease, resulting in poor expansion and inability to prepare a heat shrinkable tube with a good expansion ratio. Therefore, an appropriate amount of POE, EPDM, EPM, etc. can be added to improve the corresponding physical properties to prepare a heat shrinkable tube with a good expansion ratio.

[0247] For the heat shrinkable tubes prepared above, the preparation condition parameters of Examples 1-16 are shown in Table 1, and the preparation condition parameters of Comparative Examples 1-4 are shown in Table 2. The high-frequency and high-voltage resistance performance of the prepared heat shrinkable tubes was measured according to the above-mentioned measurement method for high-frequency and high-voltage resistance; the thermal conductivity of the prepared heat shrinkable tubes was measured according to the above-mentioned measurement method for thermal conductivity; the tensile strength and elongation at break of the prepared heat shrinkable tubes were measured according to the above-mentioned measurement method for mechanical properties. The measurement results of Examples 1-16 and Comparative Examples 1-4 are shown in Table 3.

[0248] Table 1 Preparation condition parameters of Examples 1-16

[0249]

[0250]

[0251] Table 2 Preparation condition parameters of Comparative Examples 1-4

[0252]

[0253] Table 3 Measurement results of Examples 1-16 and Comparative Examples 1-4

[0254]

[0255]

[0256] From Examples 1-16 and Comparative Example 1, it can be seen that the heat shrinkable tube made of polyethylene and insulating thermal conductive materials has a good thermal conductivity coefficient, resulting in a small temperature rise of the heat shrinkable tube under high frequency and high voltage. It realizes that at a frequency of 400±100kHz, with a voltage of 5000V, the leakage current does not exceed 100mA after withstanding voltage for 60s, meeting the safety requirement performance of GB9706.202-2021. From Examples 1, 14-16, it can be seen that after adding polyolefin elastomer, the mechanical properties of the heat shrinkable tube such as tensile strength and elongation at break have been improved. In summary, the high-frequency and high-voltage resistant heat shrinkable tube provided by the present invention has good mechanical properties, is resistant to high frequency and high voltage at the same time, and has a broad application prospect. It can not only be applied to the medical device field, but also to other high-frequency and high-voltage scenarios, and can replace the existing high-frequency and high-voltage resistant heat shrinkable tube made of PTFE material, providing a new choice for high-frequency and high-voltage resistant heat shrinkable tubes.

[0257] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A high-frequency and high-voltage resistant heat-shrinkable tube, characterized in that, Calculated by weight parts, the preparation materials of the high-frequency voltage-resistant heat-shrinkable tube include the following components: Polyethylene: 30 - 50 parts; Insulating and heat-conducting material: 25 - 50 parts.

2. The heat shrinkable tube resistant to high frequency and high voltage according to claim 1, characterized in that The tensile strength of the polyethylene is greater than 17 Mpa.

3. The heat-shrinkable tube resistant to high frequency and high voltage according to claim 1, wherein The insulating and heat-conducting material includes at least one of α-Al2O3, boron nitride, and aluminum nitride.

4. The high-frequency and high-voltage resistant heat-shrinkable tube according to claim 1, wherein The average particle size of the insulating and heat-conducting material is 1 - 10 μm.

5. The heat-shrinkable tube resistant to high frequency and high voltage according to claim 1, wherein The average particle size of the insulating and heat-conducting material is 4 - 7 μm.

6. The heat shrinkable tube resistant to high frequency and high voltage according to claim 1, wherein The preparation materials of the high-frequency high-voltage heat-shrinkable tube further include polyolefin elastomer: 5 - 10 parts, and the polyolefin elastomer includes at least one of thermoplastic elastomer polymerized by metallocene-catalyzed ethylene and α-olefin, ethylene propylene diene monomer (EPDM), and ethylene propylene copolymer (EPM).

7. The heat-shrinkable tube resistant to high frequency and high voltage according to claim 1, wherein The preparation materials of the high-frequency high-voltage heat-shrinkable tube further include compatibilizer: 1 - 5 parts, and the compatibilizer includes at least one of polyolefin elastomer graft and polyethylene graft.

8. The heat-shrinkable tube resistant to high frequency and high voltage according to claim 1, wherein The preparation materials of the high-frequency high-voltage heat-shrinkable tube further include antioxidant 0.3 - 0.5 parts, and the antioxidant includes at least one of hindered phenol main antioxidant and thioether antioxidant; Or, the preparation materials of the high-frequency high-voltage heat-shrinkable tube further include coupling agent 0.3 - 1 part, and the coupling agent includes at least one of aluminate coupling agent and titanate coupling agent; Or, the preparation materials of the high-frequency high-voltage heat-shrinkable tube further include sensitizer 0.3 - 1 part, and the sensitizer includes at least one of trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, triallyl isocyanate, or 1,3-butanediol dimethacrylate.

9. A preparation method of a high-frequency and high-voltage resistant heat-shrinkable tube, characterized in that, Including the following steps: Masterbatch processing: Mix polyethylene and insulating and heat-conducting material according to the ratio through a kneader, and then extrude, draw into strips, and pelletize through an extrusion device to obtain masterbatch particles; Extrusion into tube: Extrude the masterbatch particles obtained above through an extruder to obtain semi-finished pipe materials. Irradiation process: Irradiate the semi-finished pipe materials obtained above through an irradiation device to obtain irradiated pipe materials; Expansion molding: Expand, cool, and shape the irradiated pipe materials obtained above to obtain the high-frequency high-voltage heat-shrinkable tube.

10. The preparation method according to claim 9, characterized in that, In the masterbatch processing step, when mixing polyethylene and insulating and heat-conducting material, polyolefin elastomer, compatibilizer, antioxidant, coupling agent, or sensitizer can also be added for mixing; Or, in the masterbatch processing step, the mixing temperature of the kneader is 100 - 130 °C, and the mixing time is 10 - 20 min; Or, in the masterbatch processing step, the extrusion temperature of the extrusion device is 130 - 190 °C; Or, in the extrusion into tube step, the extrusion temperature of the extruder is 130 - 190 °C; Or, in the irradiation process step, the irradiation dose of the irradiation device is 60 - 200 KGy; Or, in the expansion molding step, the expansion temperature during expansion is 130 - 260 °C, and the expansion ratio is 2 - 3 times.

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