High-temperature radiation resistant crosslinked polyolefin heat shrinkable material and preparation method thereof

Abstract

The application relates to a high-temperature radiation crosslinking polyolefin heat shrinkable material and a preparation method thereof, and belongs to the technical field of high polymer heat shrinkable materials. According to weight parts, the preparation raw materials of the high-temperature radiation crosslinking polyolefin heat shrinkable material comprise 88-92 parts of a base material, 1.0-2.5 parts of TAIC, 0.3-0.6 parts of a hindered phenolic antioxidant, 0.3-0.6 parts of a phosphite antioxidant, 0.2-0.8 parts of polyethylene wax, 1.0-2.5 parts of a brittle resistance agent and 1.0-1.2 parts of a color change resistance agent. The composite oxide metal is prepared by matching CeO2 powder, La2O3 powder and an epoxy silane crosslinking agent; the composite fiber silk is prepared by using UHMWPE fibers, PPS fibers and the epoxy silane crosslinking agent; the brittle resistance agent prepared by the composite oxide metal and the composite fiber silk under suitable proportions and processes is added into the components of the preparation raw materials of the high-temperature radiation crosslinking polyolefin heat shrinkable materials, low-temperature aging is delayed, low-temperature mechanics and bending resistance are greatly improved, and the high-temperature radiation crosslinking polyolefin heat shrinkable material can be used for a long time under low-temperature working conditions and is not prone to brittle cracking and damage.

Description

Technical Field

[0001] This invention belongs to the field of polymer heat shrinkable materials technology, specifically relating to a high-temperature irradiation resistant cross-linked polyolefin heat shrinkable material and its preparation method. Background Technology

[0002] Polyolefin heat shrinkable materials, with their excellent heat shrinkable covering properties and stable high-temperature processing characteristics, can meet the assembly and use requirements of most common working conditions in terms of heat shrinkage ratio and short-term heat resistance of conventional products; such materials are often used in cable insulation, wire harness protection and other scenarios.

[0003] Currently, polyolefin heat-shrinkable materials have the following problems when used at low temperatures: At low temperatures, the movement of molecular chains is hindered, the rigidity of the material increases significantly and the toughness decreases rapidly. The material is prone to embrittlement and is easily cracked or even broken when bent or impacted at low temperatures, which seriously damages the integrity of the insulation protection. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material and its preparation method in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions: This invention provides a high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material. By weight, the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material include: 88-92 parts base material, 1.0-2.5 parts TAIC, 0.3-0.6 parts hindered phenolic antioxidant, 0.3-0.6 parts phosphite antioxidant, 0.2-0.8 parts polyethylene wax, 1.0-2.5 parts anti-brittleness agent, and 1.0-1.2 parts anti-color change agent. The raw materials for preparing the base material, by weight, include: 60-68 parts LLDPE and 24-32 parts EVA; The raw materials for preparing the anti-brittleness agent, by weight, include: 1.0-1.8 parts of composite fiber filaments and 0.5-1.4 parts of composite metal oxide; The raw materials for preparing the composite fiber filament, by weight, include: 0.6-1.4 parts UHMWPE fiber, 0.4-1.1 parts PPS fiber, and 0.015-0.075 parts epoxy silane crosslinking agent; The raw materials for preparing the composite metal oxide, by weight, include: 0.3-0.8 parts CeO2 powder, 0.2-0.6 parts La2O3 powder, and 0.0075-0.042 parts epoxy silane crosslinking agent.

[0006] As a further optimization of the present invention, the preparation process of the composite fiber is as follows: (i) UHMWPE fiber and PPS fiber are combined in two strands, with the draw ratio controlled at 1.00-1.05, the unwinding tension of the single filament at 15-30cN, the tension difference between the two strands ≤5cN, and the yarn speed at 180-350m / min. After the yarn is combined, it is lightly twisted in the same direction, with the twist controlled at 25-55 twists / meter, to obtain the composite yarn. (ii) Cut the composite yarn into mixed fiber raw materials with a length of 150-200μm; (iii) Add the epoxy silane crosslinking agent to a 35-45% ethanol aqueous solution. The mass ratio of the epoxy silane crosslinking agent to the 35-45% ethanol aqueous solution is 1.5-3.0:97.0-98.5. Stir at 120-130 r / min for 10-20 min to obtain a mixed solution. (iv) The pH of the mixed solution was adjusted to 4-5.5 using glacial acetic acid to obtain a modified solution for fibers; (v) Immerse the mixed fiber raw material completely in the fiber modification liquid, stir at 100-110 r / min for 15-30 min at room temperature, then take the mixed fiber raw material out of the modification liquid, and then cure and dry the mixed fiber raw material at 80-100℃ for 2-4 h to obtain composite fiber filament.

[0007] As a further optimization of the present invention, the UHMWPE fiber is 80-150D and the PPS fiber is 80-150D.

[0008] As a further optimization of the present invention, the preparation process of the composite metal oxide is as follows: (a) Mix and stir CeO2 powder and La2O3 powder evenly to obtain a mixed powder; (ii) Add the epoxy silane crosslinking agent to a 35-45% ethanol aqueous solution. The mass ratio of the epoxy silane crosslinking agent to the 35-45% ethanol aqueous solution is 1.5-3.0:97.0-98.5. Stir at 120-130 r / min for 8-10 min, and then adjust the pH of the mixed solution to 4-5.5 with glacial acetic acid to obtain a metal-modified solution. (iii) Immerse the mixed powder completely in the metal modification liquid, stir at 100-110 r / min for 30-40 min at room temperature, then remove the mixed powder from the modification liquid, and then cure and dry the mixed powder at 80-100℃ for 2-4 h to obtain composite metal oxide.

[0009] As a further optimization of the present invention, the preparation process of the anti-brittleness agent is as follows: (a) The composite fiber filaments and composite metal oxide are stirred at 60-90 r / min for 10-15 min to obtain an anti-brittleness agent.

[0010] As a further optimization of the present invention, the raw materials for preparing the anti-color change agent, by weight, include: 3-4 parts of ultraviolet absorber, 0.4-0.8 parts of hindered amine light stabilizer, and 1-1.2 parts of anti-adhesion agent; The raw materials for preparing the anti-adhesion agent, by weight, include: 5-6 parts of hydroxyl-terminated hydrogenated polybutadiene, 5-6 parts of dihydroxyl-terminated polyisoprene, 3-4 parts of branched dodecanediol, 3-4 parts of isooctyl branched fatty diol, 2-3 parts of octadecyl glycidyl ether modified polycaprolactone polyol, and 2-3 parts of stearyl epoxy-terminated polyadipate polyol.

[0011] As a further optimization of the present invention, the preparation process of the anti-adhesion agent is as follows: (i) Hydrogen-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol are added to a closed reactor. A nitrogen atmosphere is maintained inside the reactor, and the temperature inside the reactor is controlled at 20-24℃. The mixture is stirred at 80-110 r / min for 20-24 min to obtain a mixture. (ii) Under nitrogen atmosphere protection, adjust the temperature inside the reactor to 85-95℃ and stir at 80-110r / min for 3-4h. Then, let it cool naturally to room temperature to obtain the anti-adhesion agent.

[0012] As a further optimization of the present invention, the preparation process of the anti-color change agent is as follows: (a) Stir the ultraviolet absorber, hindered amine light stabilizer and anti-adhesion agent at 120-140 r / min for 20-26 min to obtain the anti-color change agent.

[0013] A method for preparing the above-mentioned high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material includes the following steps: S1, mix LLDPE and EVA evenly to obtain the base material; S2, the base material, TAIC, hindered phenolic antioxidant, phosphite antioxidant, polyethylene wax, anti-brittleness agent, and anti-color change agent are sequentially added to a twin-screw extruder for melt mixing. The twin-screw extruder temperature is divided into three zones: zone 1 160-165℃, zone 2 170-178℃, zone 3 180-185℃, and die 185-190℃. The screw speed is 220-260 r / min. The extrusion is pelletized into granules with a particle diameter of 2.5-3.5 mm and a length of 3-5 mm to obtain masterbatch. S3. The masterbatch is fed into a single-screw extruder. The extruder section temperatures are: barrel zone 1 170-175℃, zone 2 178-184℃, zone 3 186-190℃, and die head 190-195℃. The screw speed is 40-70 r / min, and the die head extrusion pressure is 8-14 MPa to obtain tubular preforms. S4, crosslinking of tubular preforms by electron beam irradiation, with irradiation dose controlled at 80-120 kGy; S5. The irradiated tubular blank is heated to 110-130℃, expanded by 2.5-4 times with compressed air and shaped, cooled in a circulating cold water bath at 20-30℃, with a traction speed of 8-15m / min, and finally wound up to obtain a high-temperature irradiated cross-linked polyolefin heat shrinkable material.

[0014] The beneficial effects of this invention are as follows: a composite metal oxide is prepared by combining CeO2 powder, La2O3 powder, and epoxy silane crosslinking agent; a composite fiber filament is prepared by combining UHMWPE fiber, PPS fiber, and epoxy silane crosslinking agent; and an anti-brittleness agent prepared by combining the composite metal oxide and composite fiber filament in a suitable ratio and process is added to the components of the raw materials for preparing high-temperature irradiation crosslinked polyolefin heat shrinkable material, which delays low-temperature aging, significantly improves low-temperature mechanical properties and bending resistance, and can be used for a long time under low-temperature conditions without easily developing brittleness or breakage problems. It is suitable for harsh low-temperature protection scenarios such as cables and vehicle wiring harnesses in cold regions. An anti-adhesion agent was prepared from hydroxyl-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol. An anti-color change agent was prepared from ultraviolet absorbers, hindered amine light stabilizers, and the anti-adhesion agent and added to the components of the raw materials for the preparation of high-temperature radiation-resistant cross-linked polyolefin heat-shrinkable material. Contaminants are easily wiped away, and external stains are prevented from penetrating inward. It effectively inhibits yellowing and spotting of pipes from both the inside and outside, significantly improves long-term appearance stability, and ensures that the cable harness covering layer has a clean appearance without stains or yellowing after long-term use. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the composition, structure, and mechanism of action of the irradiated cross-linked polyolefin heat-shrinkable material in this invention. Detailed Implementation

[0016] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0017] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products.

[0018] In this invention: TAIC: Triallyl isocyanurate produced by Hunan Fada Technology Co., Ltd. under the model name FARIDA TAIC-S; Hindered phenolic antioxidants: Irganox 1010, a hindered phenolic antioxidant manufactured by BASF SE, is used. Phosphite antioxidants: Irgafos 168, a phosphite co-antioxidant manufactured by BASF SE; Polyethylene wax: LH-100 polyethylene wax produced by Shandong Luhua Hongjin New Material Group Co., Ltd. LLDPE: The LLDPE used is 7042 linear low-density polyethylene produced by China National Petroleum Corporation Daqing Petrochemical Company. EVA: Model 18J3 ethylene-vinyl acetate copolymer produced by Beijing Dongfang Petrochemical Co., Ltd. UHMWPE fiber: TD-100 ultra-high molecular weight polyethylene fiber produced by Shandong Tongda Special Fiber Co., Ltd. PPS fiber: PPS-120 polyphenylene sulfide fiber produced by Sichuan Amphenol High-Tech Materials Co., Ltd. Epoxy silane crosslinking agent: USi-2301 (KH-560) epoxy silane coupling agent produced by Nanjing Liansilicon Chemical Co., Ltd. Ultraviolet absorber: Tiangang UV-237 benzotriazole ultraviolet absorber, manufactured by Beijing Tiangang Additives Co., Ltd. Hindered amine light stabilizer: The hindered amine light stabilizer, model Tiangang HS-944, manufactured by Beijing Tiangang Additives Co., Ltd., is used. Hydroxyl-terminated hydrogenated polybutadiene: POLYVEST HT hydroxyl-terminated hydrogenated polybutadiene manufactured by Evonik Industries; Hydroxyl-terminated polyisoprene: NISSO HI-100 hydroxyl-terminated polyisoprene manufactured by Nippon Soda Corporation; Branched dodecanediol: L12 branched dodecanediol produced by BASF SE; Isooctyl branched fatty diol: The product is IO-8 isooctyl branched fatty diol manufactured by Henkel Group, Germany; Octadecyl glycidyl ether modified polycaprolactone polyol: The polycaprolactone polyol with model number JS-CL18 produced by Jiangsu Jiasheng New Material Co., Ltd. is used. Stearyl epoxy-terminated polyadipate polyol: The stearyl epoxy-terminated polyadipate polyol of model WH-AD is produced by Zhejiang Wanhua Chemical New Materials Co., Ltd. CeO2 (cerium oxide) powder: GRI-Ce02 produced by GRINM Rare Earth New Materials Co., Ltd. La2O3 (lanthanum oxide) powder: The powder used is GRI-La01 produced by GRINM Rare Earth New Materials Co., Ltd.

[0019] I. Implementation Examples Example 1 A high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material, wherein the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material include: 88 parts base material, 1.0 part TAIC, 0.3 parts hindered phenolic antioxidant, 0.3 parts phosphite antioxidant, 0.2 parts polyethylene wax, 1.0 part anti-brittleness agent, and 1.0 part anti-color change agent; The raw materials for preparing the base material, by weight, include: 60 parts LLDPE and 24 parts EVA; The raw materials for preparing the anti-brittleness agent, by weight, include: 1.0 part composite fiber filament and 0.5 part composite metal oxide; The raw materials for preparing the composite fiber filaments, by weight, include: 0.6 parts UHMWPE fiber, 0.4 parts PPS fiber, and 0.015 parts epoxy silane crosslinking agent; The raw materials for preparing the composite metal oxide, by weight, include: 0.3 parts CeO2 powder, 0.2 parts La2O3 powder, and 0.0075 parts epoxy silane crosslinking agent; The raw materials for preparing the anti-color change agent, by weight, include: 3 parts ultraviolet absorber, 0.4 parts hindered amine light stabilizer, and 1 part anti-adhesion agent; The raw materials for preparing the anti-adhesion agent, by weight, include: 5 parts of hydroxyl-terminated hydrogenated polybutadiene, 5 parts of dihydroxyl-terminated polyisoprene, 3 parts of branched dodecanediol, 3 parts of isooctyl branched fatty diol, 2 parts of octadecyl glycidyl ether modified polycaprolactone polyol, and 2 parts of stearyl epoxy-terminated polyadipate polyol. The above-mentioned method for preparing high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material includes the following steps: LLDPE and EVA are mixed and stirred evenly to obtain the base material; The preparation process of composite fiber yarn is as follows: (I) UHMWPE fiber and PPS fiber (UHMWPE fiber is 80D, PPS fiber is 80D) are combined in a two-strand method, the yarn draw ratio is controlled at 1.00, the unwinding tension of the single filament is 15cN, the tension difference between the two strands is 5cN, and the yarn speed is 180m / min; after the yarn is combined, it is lightly twisted in the same direction, and the twist is controlled at 25 twists / meter to obtain composite yarn; (II) The composite yarn is cut into mixed fiber raw materials with a length of 150μm; (III) Epoxy silane is crosslinked. Add the agent to a 35% ethanol aqueous solution. The mass ratio of epoxy silane crosslinking agent to 35% ethanol aqueous solution is 1.5:97. Stir at 120 r / min for 10 min to obtain a mixed solution. (iv) Adjust the pH of the mixed solution to 4 using glacial acetic acid to obtain a fiber modification solution. (v) Completely immerse the mixed fiber raw material in the fiber modification solution. Stir at 100 r / min for 15 min at room temperature. Remove the mixed fiber raw material from the modification solution. Then, cure and dry the mixed fiber raw material at 80℃ for 2 h to obtain composite fiber filaments. The preparation process of composite metal oxide is as follows: (i) CeO2 powder and La2O3 powder are uniformly mixed and stirred to obtain a mixed powder; (ii) Epoxy silane crosslinking agent is added to 35% ethanol aqueous solution, the mass ratio of epoxy silane crosslinking agent to 35% ethanol aqueous solution is 1.5:97.0, and stirred at 120 r / min for 8 min. Then, the pH value of the mixed solution is adjusted to 4 with glacial acetic acid to obtain a metal modification solution; (iii) The mixed powder is completely immersed in the metal modification solution. After stirring at 100 r / min for 30 min at room temperature, the mixed powder is taken out from the modification solution. Then, the mixed powder is cured and dried at 80℃ for 2 h to obtain composite metal oxide. The preparation process of the anti-brittleness agent is as follows: (i) The composite fiber filament and the composite metal oxide are stirred at 60 r / min for 10 min to obtain the anti-brittleness agent; The preparation process of the anti-adhesion agent is as follows: (I) Hydrogen-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol are put into a closed reactor. The reactor is kept under a nitrogen atmosphere and the temperature inside the reactor is controlled at 20°C. The mixture is stirred at 80 r / min for 20 min to obtain a mixture; (II) Under the protection of a nitrogen atmosphere, the temperature inside the reactor is adjusted to 85°C and stirred at 80 r / min for 3 h. Then, the mixture is allowed to cool naturally to room temperature to obtain the anti-adhesion agent. The preparation process of the anti-color change agent is as follows: (i) stir the ultraviolet absorber, hindered amine light stabilizer and anti-adhesion agent at 120 r / min for 20 min to obtain the anti-color change agent; The base material, TAIC, hindered phenolic antioxidants, phosphite antioxidants, polyethylene wax, anti-brittleness agent, and anti-color change agent are sequentially added to a twin-screw extruder for melt mixing. The twin-screw extruder temperature is divided into three zones: zone 1 160℃, zone 2 170℃, zone 3 180℃, and die 185℃. The screw speed is 220 r / min. The extrusion is pelletized and granulated to obtain masterbatch with a particle diameter of 2.5 mm and a length of 3 mm. The masterbatch is fed into a single-screw extruder. The extruder section temperatures are: 170℃ in the first zone of the barrel, 178℃ in the second zone, 186℃ in the third zone, and 190℃ in the die. The screw speed is 40 r / min, and the die extrusion pressure is 8 MPa to produce tubular preforms. The tubular preform was crosslinked by electron beam irradiation, with the irradiation dose controlled at 80 kGy; The irradiated tubular blank was heated to 110°C, expanded 2.5 times with compressed air and shaped, cooled in a 20°C circulating cold water bath, drawn at a speed of 8m / min, and finally wound up to obtain a high-temperature irradiated cross-linked polyolefin heat-shrinkable material.

[0020] Example 2 A high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material, wherein the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material include: 90 parts base material, 1.75 parts TAIC, 0.45 parts hindered phenolic antioxidant, 0.45 parts phosphite antioxidant, 0.5 parts polyethylene wax, 1.75 parts anti-brittleness agent, and 1.1 parts anti-color change agent; The raw materials for preparing the base material, by weight, include: 64 parts LLDPE and 28 parts EVA; The raw materials for preparing the anti-brittleness agent, by weight, include: 1.4 parts composite fiber filaments and 0.95 parts composite metal oxide. The raw materials for preparing the composite fiber filaments, by weight, include: 1 part UHMWPE fiber, 0.75 parts PPS fiber, and 0.045 parts epoxy silane crosslinking agent. The raw materials for preparing the composite metal oxide, by weight, include: 0.55 parts CeO2 powder, 0.4 parts La2O3 powder, and 0.02475 parts epoxy silane crosslinking agent. The raw materials for preparing the anti-color change agent, by weight, include: 3.5 parts ultraviolet absorber, 0.6 parts hindered amine light stabilizer, and 1.1 parts anti-adhesion agent; The raw materials for preparing the anti-adhesion agent, by weight, include: 5.5 parts of hydroxyl-terminated hydrogenated polybutadiene, 5.5 parts of dihydroxyl-terminated polyisoprene, 3.5 parts of branched dodecanediol, 3.5 parts of isooctyl branched fatty diol, 2.5 parts of octadecyl glycidyl ether modified polycaprolactone polyol, and 2.5 parts of stearyl epoxy-terminated polyadipate polyol. The above-mentioned method for preparing high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material includes the following steps: LLDPE and EVA are mixed and stirred evenly to obtain the base material; The preparation process of composite fiber yarn is as follows: (I) UHMWPE fiber and PPS fiber (UHMWPE fiber is 115D, PPS fiber is 115D) are combined in a two-strand combination manner, the yarn draw ratio is controlled at 1.025, the unwinding tension of the single filament is 22.5cN, the tension difference between the two strands is 5cN, and the yarn speed is 265m / min; after the yarn is combined, it is lightly twisted in the same direction, and the twist is controlled at 40 twists / meter to obtain composite yarn; (II) The composite yarn is cut into mixed fiber raw materials with a length of 175μm; (III) Epoxy silane crosslinking agent is added The epoxy silane crosslinking agent and the 40% ethanol aqueous solution are mixed in a mass ratio of 2.25:97.75. The mixture is stirred at 125 r / min for 15 min to obtain a mixed solution. (iv) The pH of the mixed solution is adjusted to 4.75 with glacial acetic acid to obtain a fiber modification solution. (v) The mixed fiber raw material is completely immersed in the fiber modification solution. The mixture is stirred at 105 r / min for 22.5 min at room temperature. The mixed fiber raw material is then removed from the modification solution. Subsequently, the mixed fiber raw material is cured and dried at 90℃ for 3 h to obtain composite fiber filaments. The preparation process of composite metal oxide is as follows: (i) CeO2 powder and La2O3 powder are uniformly mixed and stirred to obtain a mixed powder; (ii) Epoxy silane crosslinking agent is added to 40% ethanol aqueous solution, the mass ratio of epoxy silane crosslinking agent to 40% ethanol aqueous solution is 2.25:97.75, and stirred at 125 r / min for 9 min. Then, the pH value of the mixed solution is adjusted to 4.75 with glacial acetic acid to obtain a metal modification solution; (iii) The mixed powder is completely immersed in the metal modification solution. After stirring at 105 r / min for 35 min at room temperature, the mixed powder is taken out from the modification solution. Then, the mixed powder is cured and dried at 90℃ for 3 h to obtain composite metal oxide. The preparation process of the anti-brittleness agent is as follows: (i) The composite fiber filament and the composite metal oxide are stirred at 75 r / min for 12.5 min to obtain the anti-brittleness agent; The preparation process of the anti-adhesion agent is as follows: (I) Hydrogen-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol are put into a closed reactor. The reactor is kept under a nitrogen atmosphere and the temperature inside the reactor is controlled at 22°C. The mixture is stirred at 90 r / min for 22 min to obtain a mixture; (II) Under the protection of a nitrogen atmosphere, the temperature inside the reactor is adjusted to 90°C and stirred at 95 r / min for 3.5 h. Then, the mixture is allowed to cool naturally to room temperature to obtain the anti-adhesion agent. The preparation process of the anti-color change agent is as follows: (i) stir the ultraviolet absorber, hindered amine light stabilizer and anti-adhesion agent at 130 r / min for 23 min to obtain the anti-color change agent; The base material, TAIC, hindered phenolic antioxidants, phosphite antioxidants, polyethylene wax, anti-brittleness agent, and anti-color change agent are sequentially added to a twin-screw extruder for melt mixing. The twin-screw extruder temperature is divided into three zones: zone 1 162.5℃, zone 2 174℃, zone 3 182.5℃, and die head 187.5℃. The screw speed is 240 r / min. The extrusion is pelletized to obtain masterbatch with a particle diameter of 3 mm and a length of 4 mm. The masterbatch is fed into a single-screw extruder. The extruder section temperatures are: 172.5℃ in zone 1 of the barrel, 181℃ in zone 2, 188℃ in zone 3, and 192.5℃ in the die. The screw speed is 55 r / min, and the die extrusion pressure is 11 MPa, to produce a tubular billet. The tubular preform was crosslinked by electron beam irradiation, with the irradiation dose controlled at 100 kGy. The irradiated tubular blank was heated to 120°C, expanded 3.25 times with compressed air and shaped, cooled in a 25°C circulating cold water bath, drawn at a speed of 11.5 m / min, and finally wound up to obtain a high-temperature irradiated cross-linked polyolefin heat-shrinkable material.

[0021] Example 3 A high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material, wherein the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material include: 92 parts base material, 2.5 parts TAIC, 0.6 parts hindered phenolic antioxidant, 0.6 parts phosphite antioxidant, 0.8 parts polyethylene wax, 2.5 parts anti-brittleness agent, and 1.2 parts anti-color change agent; The raw materials for preparing the base material, by weight, include: 68 parts LLDPE and 32 parts EVA; The raw materials for preparing the anti-brittleness agent, by weight, include: 1.8 parts composite fiber filaments and 1.4 parts composite metal oxide. The raw materials for preparing the composite fiber filaments, by weight, include: 1.4 parts UHMWPE fiber, 1.1 parts PPS fiber, and 0.075 parts epoxy silane crosslinking agent. The raw materials for preparing the composite metal oxide, by weight, include: 0.8 parts CeO2 powder, 0.6 parts La2O3 powder, and 0.042 parts epoxy silane crosslinking agent; The raw materials for preparing the anti-color change agent, by weight, include: 4 parts ultraviolet absorber, 0.8 parts hindered amine light stabilizer, and 1.2 parts anti-adhesion agent. The raw materials for preparing the anti-adhesion agent, by weight, include: 6 parts of hydroxyl-terminated hydrogenated polybutadiene, 6 parts of dihydroxyl-terminated polyisoprene, 4 parts of branched dodecanediol, 4 parts of isooctyl branched fatty diol, 3 parts of octadecyl glycidyl ether modified polycaprolactone polyol, and 3 parts of stearyl epoxy-terminated polyadipate polyol. The above-mentioned method for preparing high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material includes the following steps: LLDPE and EVA are mixed and stirred evenly to obtain the base material; The preparation process of composite fiber yarn is as follows: (I) UHMWPE fiber and PPS fiber (UHMWPE fiber is 150D, PPS fiber is 150D) are combined in a two-strand method, the yarn draw ratio is controlled at 1.05, the unwinding tension of the single filament is 30cN, the tension difference between the two strands is 5cN, and the yarn speed is 350m / min; after the yarn is combined, it is lightly twisted in the same direction, and the twist is controlled at 55 twists / meter to obtain composite yarn; (II) The composite yarn is cut into mixed fiber raw materials with a length of 200μm; (III) Epoxy silane is crosslinked. Add the agent to a 45% ethanol aqueous solution. The mass ratio of epoxy silane crosslinking agent to 45% ethanol aqueous solution is 3:98.5. Stir at 130 r / min for 20 min to obtain a mixed solution. (iv) Adjust the pH of the mixed solution to 5.5 with glacial acetic acid to obtain a fiber modification solution. (v) Completely immerse the mixed fiber raw material in the fiber modification solution. Stir at 110 r / min for 30 min at room temperature. Remove the mixed fiber raw material from the modification solution. Then, cure and dry the mixed fiber raw material at 100℃ for 4 h to obtain composite fiber filaments. The preparation process of the composite metal oxide is as follows: (i) CeO2 powder and La2O3 powder are uniformly mixed and stirred to obtain a mixed powder; (ii) Epoxy silane crosslinking agent is added to 45% ethanol aqueous solution, the mass ratio of epoxy silane crosslinking agent to 45% ethanol aqueous solution is 3:98.5, and stirred at 130 r / min for 10 min. Then, the pH value of the mixed solution is adjusted to 5.5 with glacial acetic acid to obtain a metal modification solution; (iii) The mixed powder is completely immersed in the metal modification solution. After stirring at 110 r / min for 40 min at room temperature, the mixed powder is taken out from the modification solution. Then, the mixed powder is cured and dried at 100℃ for 4 h to obtain the composite metal oxide. The preparation process of the anti-brittleness agent is as follows: (i) The composite fiber filament and the composite metal oxide are stirred at 90 r / min for 15 min to obtain the anti-brittleness agent; The preparation process of the anti-adhesion agent is as follows: (I) Hydrogen-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol are put into a closed reactor. The reactor is kept under a nitrogen atmosphere and the temperature inside the reactor is controlled at 24°C. The mixture is stirred at 110 r / min for 24 min to obtain a mixture; (II) Under the protection of a nitrogen atmosphere, the temperature inside the reactor is adjusted to 95°C and stirred at 110 r / min for 4 h. Then, the mixture is allowed to cool naturally to room temperature to obtain the anti-adhesion agent. The preparation process of the anti-color change agent is as follows: (i) stir the ultraviolet absorber, hindered amine light stabilizer and anti-adhesion agent at 140 r / min for 26 min to obtain the anti-color change agent; The base material, TAIC, hindered phenolic antioxidants, phosphite antioxidants, polyethylene wax, anti-brittleness agent, and anti-color change agent are sequentially added to a twin-screw extruder for melt mixing. The twin-screw extruder temperature is divided into three zones: zone 1 165℃, zone 2 178℃, zone 3 185℃, and die 190℃. The screw speed is 260 r / min. The extrusion is pelletized and granulated to obtain masterbatch with a particle diameter of 3.5 mm and a length of 5 mm. The masterbatch is fed into a single-screw extruder. The extruder section temperatures are: 175℃ in the first zone of the barrel, 184℃ in the second zone, 190℃ in the third zone, and 195℃ in the die. The screw speed is 70 r / min, and the die extrusion pressure is 14 MPa to produce tubular preforms. The tubular preform was crosslinked by electron beam irradiation, with the irradiation dose controlled at 120 kGy. The irradiated tubular blank is heated to 130°C, expanded 4 times with compressed air and shaped, cooled in a 30°C circulating cold water bath, drawn at a speed of 15m / min, and finally wound up to obtain a high-temperature irradiated cross-linked polyolefin heat-shrinkable material.

[0022] II. Comparative Example 1. Replace the anti-brittleness agent in Example 2 with the anti-brittleness agent described in Table 1 below, and the remaining steps are the same as in Example 2: ; Table 1 In Table 1, "-" indicates that no addition is needed.

[0023] 2. Replace the composite fiber filaments in Example 2 with the composite fiber filaments described in Table 2 below, and the remaining steps are the same as in Example 2: ; Table 2 In Table 2, "-" indicates that no addition is needed.

[0024] 3. Replace the composite metal oxide in Example 2 with the composite metal oxides described in Table 3 below, and the remaining steps are the same as in Example 2: ; Table 3 In Table 3, "-" indicates that no addition is needed.

[0025] 4. Replace the anti-color change agent in Example 3 with the anti-color change agent described in Table 4 below, and the remaining steps are the same as in Example 2: ; Table 4 In Table 4, "-" indicates that no addition is needed.

[0026] 5. Replace the anti-adhesion agent in Example 3 with the anti-adhesion agent described in Table 5 below, and the remaining steps are the same as in Example 2: ; Table 5 In Table 5, "-" indicates that no addition is needed.

[0027] III. Testing Experiments 1. Low-temperature shatter resistance test ①The low-temperature brittleness resistance of the high-temperature irradiated cross-linked polyolefin heat shrinkable materials prepared in Examples 1-3 and Comparative Examples 1-11 was tested according to GB / T 5470-2008 "Determination of embrittlement temperature of plastics by impact method". The results are shown in Table 6. ②According to GB / T 2423.14-2008 "Environmental Testing for Electrical and Electronic Products - Test Nb: Low Temperature Bending", the high temperature irradiation crosslinked polyolefin heat shrinkable materials prepared in Examples 1-3 and Comparative Examples 1-11 were subjected to a -55℃ low temperature chamber for 1 hour and a standard mandrel 180° bending test. The results are shown in Table 7. ③According to GB / T 1040.2-2018 "Determination of Tensile Properties of Plastics", the high-temperature irradiation cross-linked polyolefin heat shrinkable materials prepared in Examples 1-3 and Comparative Examples 1-11 were tested for low-temperature elongation at break and low-temperature tensile strength in a low-temperature environment chamber (-40℃). The results are shown in Table 8. ④ The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable materials prepared in Examples 1-3 and Comparative Examples 1-11 were subjected to thermal shock tests according to the thermal shock clause of GB / T 7113.2-2014 "Insulating hoses - Part 2: Test methods". The results are shown in Table 9. ⑤ Long-term thermal aging tests were conducted on the high-temperature irradiated cross-linked polyolefin heat shrinkable materials prepared in Examples 1-3 and Comparative Examples 1-11 in accordance with GB / T 2951.31-2008 "General Tests for Thermal Aging of Cable Insulation Sheaths". The results are shown in Table 10. ⑥ The heat shrinkage rate of the high-temperature irradiation crosslinked polyolefin heat shrinkage materials prepared in Examples 1-3 and Comparative Examples 1-11 was tested according to GB / T 34848-2017 "Test Method for Shrinkage Performance of Heat Shrinkable Films". The results are shown in Table 11. ; Table 6 ; Table 7 ; Table 8 ; Table 9 ; Table 10 ; Table 11 As can be seen from Table 6-11 above, the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material prepared in Example 2 is made by combining CeO2 powder, La2O3 powder, and epoxy silane cross-linking agent to prepare a composite metal oxide, and by preparing composite fiber filaments from UHMWPE fiber, PPS fiber, and epoxy silane cross-linking agent. An anti-brittleness agent prepared by using the composite metal oxide and composite fiber filaments in a suitable ratio and process is added to the components of the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material. The material has a brittleness temperature as low as -56.3℃, no sample cracking in the bending test at -55℃, and a low-temperature tensile strength of 21.7MPa and an elongation at break of 486% at -40℃. After silane modification, the rare earth powder delays low-temperature aging, and the fibers synergistically construct a stress buffer network, effectively preventing crack propagation. Compared with the other examples and all comparative examples, the low-temperature mechanical properties and bending resistance are significantly improved. It can be used for a long time in low-temperature conditions and is not prone to brittleness or breakage. It is particularly suitable for the protection of outdoor cables and engineering machinery wire harnesses in cold weather.

[0028] 2. Resistance to discoloration test ①The color change resistance of the high-temperature irradiation cross-linked polyolefin heat shrinkable materials prepared in Example 2 and Comparative Examples 12-28 was tested according to GB / T 34033-2017 "Test Method for UV Aging Resistance of Plastics". The results are shown in Table 12. Among them, the high-temperature irradiation cross-linked polyolefin heat shrinkable material prepared produces a semi-transparent milky white finished heat shrink tube without the addition of external color powder; The experimental conditions were as follows: ultraviolet radiation intensity 0.89 W / (m²). 2 •nm), temperature 60℃, continuous irradiation for 500h; The L, a, and b* values ​​of the sample before and after aging were measured using a colorimeter, and the total color difference ΔE was calculated. The general grading standard in the cable heat shrink tubing industry is: ΔE < 2 is excellent, 2~5 is slight yellowing, and ΔE > 5 is severe yellowing. The data advantage is more intuitive after adding the standard. ②According to GB / T 7113.2-2014 "Insulating hoses - tests for contamination resistance and color migration resistance", the high-temperature irradiation-resistant cross-linked polyolefin heat shrinkable materials prepared in Example 2 and Comparative Examples 19-28 were subjected to material adhesion contamination-induced color change tests. The results are shown in Table 13. Among them, the simulated on-site attached pollution sources are: mineral insulating lubricating oil, black conductive carbon black dust, and colored wire harness marking ink. The three types of pollutants are mixed evenly as the attached pollution medium, with the ratio of mineral oil: carbon black: ink = 10:1:2. ; ; Table 12 ; Table 13 As can be seen from Tables 12 and 13 above, compared with Comparative Examples 12-19, the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material prepared in Example 2 exhibits the best anti-color change ability. Among them, the anti-adhesion agent prepared by hydroxyl-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol, and the anti-color change agent prepared by ultraviolet absorber, hindered amine light stabilizer, and anti-adhesion agent were added to the components of the raw materials for preparing the high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material. After ultraviolet aging, the total color difference was only 1.38, which was much lower than all the comparative examples; after the oil and dust adhesion test, the color difference was only 1.46. The pollutants were very easy to wipe away, and the material prevented external stains from penetrating inward. It effectively inhibited the yellowing and spotting of the pipe from both the inside and outside, significantly improved the long-term appearance stability, and was not easily discolored by oil and dust after long-term wrapping of cable harnesses.

[0029] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material, characterized in that, By weight, the raw materials for preparing the high-temperature irradiation-resistant crosslinked polyolefin heat-shrinkable material include: 88-92 parts base material, 1.0-2.5 parts TAIC, 0.3-0.6 parts hindered phenolic antioxidant, 0.3-0.6 parts phosphite antioxidant, 0.2-0.8 parts polyethylene wax, 1.0-2.5 parts anti-brittleness agent, and 1.0-1.2 parts anti-color change agent; The raw materials for preparing the base material, by weight, include: 60-68 parts LLDPE and 24-32 parts EVA; The raw materials for preparing the anti-brittleness agent, by weight, include: 1.0-1.8 parts of composite fiber filaments and 0.5-1.4 parts of composite metal oxide; The raw materials for preparing the composite fiber filament, by weight, include: 0.6-1.4 parts UHMWPE fiber, 0.4-1.1 parts PPS fiber, and 0.015-0.075 parts epoxy silane crosslinking agent; The raw materials for preparing the composite metal oxide, by weight, include: 0.3-0.8 parts CeO2 powder, 0.2-0.6 parts La2O3 powder, and 0.0075-0.042 parts epoxy silane crosslinking agent.

2. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 1, characterized in that, The preparation process of the composite fiber is as follows: (i) UHMWPE fiber and PPS fiber are combined in two strands, with the draw ratio controlled at 1.00-1.05, the unwinding tension of the single filament at 15-30cN, the tension difference between the two strands ≤5cN, and the yarn speed at 180-350m / min. After the yarn is combined, it is lightly twisted in the same direction, with the twist controlled at 25-55 twists / meter, to obtain the composite yarn. (ii) Cut the composite yarn into mixed fiber raw materials with a length of 150-200μm; (iii) Add the epoxy silane crosslinking agent to a 35-45% ethanol aqueous solution. The mass ratio of the epoxy silane crosslinking agent to the 35-45% ethanol aqueous solution is 1.5-3.0:97.0-98.

5. Stir at 120-130 r / min for 10-20 min to obtain a mixed solution. (iv) The pH of the mixed solution was adjusted to 4-5.5 using glacial acetic acid to obtain a modified solution for fibers; (v) Immerse the mixed fiber raw material completely in the fiber modification liquid, stir at 100-110 r / min for 15-30 min at room temperature, then take the mixed fiber raw material out of the modification liquid, and then cure and dry the mixed fiber raw material at 80-100℃ for 2-4 h to obtain composite fiber filament.

3. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 1, characterized in that, The UHMWPE fiber is 80-150D, and the PPS fiber is 80-150D.

4. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 1, characterized in that, The preparation process of the composite metal oxide is as follows: (a) Mix and stir CeO2 powder and La2O3 powder evenly to obtain mixed powder; (ii) Add the epoxy silane crosslinking agent to a 35-45% ethanol aqueous solution. The mass ratio of the epoxy silane crosslinking agent to the 35-45% ethanol aqueous solution is 1.5-3.0:97.0-98.

5. Stir at 120-130 r / min for 8-10 min, and then adjust the pH of the mixed solution to 4-5.5 with glacial acetic acid to obtain a metal-modified solution. (iii) Immerse the mixed powder completely in the metal modification liquid, stir at 100-110 r / min for 30-40 min at room temperature, then remove the mixed powder from the modification liquid, and then cure and dry the mixed powder at 80-100℃ for 2-4 h to obtain composite metal oxide.

5. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 1, characterized in that, The preparation process of the anti-brittleness agent is as follows: (a) The composite fiber filaments and composite metal oxide are stirred at 60-90 r / min for 10-15 min to obtain an anti-brittleness agent.

6. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 1, characterized in that, The raw materials for preparing the anti-color change agent, by weight, include: 3-4 parts of ultraviolet absorber, 0.4-0.8 parts of hindered amine light stabilizer, and 1-1.2 parts of anti-adhesion agent; The raw materials for preparing the anti-adhesion agent, by weight, include: 5-6 parts of hydroxyl-terminated hydrogenated polybutadiene, 5-6 parts of dihydroxyl-terminated polyisoprene, 3-4 parts of branched dodecanediol, 3-4 parts of isooctyl branched fatty diol, 2-3 parts of octadecyl glycidyl ether modified polycaprolactone polyol, and 2-3 parts of stearyl epoxy-terminated polyadipate polyol.

7. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 6, characterized in that, The preparation process of the anti-adhesion agent is as follows: (i) Hydrogen-terminated hydrogenated polybutadiene, dihydroxyl-terminated polyisoprene, branched dodecanediol, isooctyl branched fatty diol, octadecyl glycidyl ether modified polycaprolactone polyol, and stearyl epoxy-terminated polyadipate polyol are added to a closed reactor. A nitrogen atmosphere is maintained inside the reactor, and the temperature inside the reactor is controlled at 20-24℃. The mixture is stirred at 80-110 r / min for 20-24 min to obtain a mixture. (ii) Under nitrogen atmosphere protection, adjust the temperature inside the reactor to 85-95℃ and stir at 80-110r / min for 3-4h. Then, let it cool naturally to room temperature to obtain the anti-adhesion agent.

8. The high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to claim 7, characterized in that, The preparation process of the anti-color change agent is as follows: (a) Stir the ultraviolet absorber, hindered amine light stabilizer and anti-adhesion agent at 120-140 r / min for 20-26 min to obtain the anti-color change agent.

9. A method for preparing a high-temperature irradiation-resistant cross-linked polyolefin heat-shrinkable material according to any one of claims 1-8, characterized in that, Includes the following steps: S1, mix LLDPE and EVA evenly to obtain the base material; S2, the base material, TAIC, hindered phenolic antioxidant, phosphite antioxidant, polyethylene wax, anti-brittleness agent, and anti-color change agent are sequentially added to a twin-screw extruder for melt mixing. The twin-screw extruder temperature is divided into three zones: zone 1 160-165℃, zone 2 170-178℃, zone 3 180-185℃, and die 185-190℃. The screw speed is 220-260 r / min. The extrusion is pelletized into granules with a particle diameter of 2.5-3.5 mm and a length of 3-5 mm to obtain masterbatch. S3. The masterbatch is fed into a single-screw extruder. The extruder section temperatures are: barrel zone 1 170-175℃, zone 2 178-184℃, zone 3 186-190℃, and die head 190-195℃. The screw speed is 40-70 r / min, and the die head extrusion pressure is 8-14 MPa to obtain tubular preforms. S4, crosslinking of tubular preforms by electron beam irradiation, with irradiation dose controlled at 80-120 kGy; S5. The irradiated tubular blank is heated to 110-130℃, expanded by 2.5-4 times with compressed air and shaped, cooled in a circulating cold water bath at 20-30℃, with a traction speed of 8-15m / min, and finally wound up to obtain a high-temperature irradiated cross-linked polyolefin heat shrinkable material.

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