Peroxide crosslinked polyethylene injection molding material for thermoplastic umbrella skirt and preparation method of peroxide crosslinked polyethylene injection molding material

Abstract

The invention provides a peroxide cross-linked polyethylene injection molding material for a thermoplastic umbrella skirt and a preparation method thereof, the thermoplastic umbrella skirt is made of a peroxide cross-linked polyethylene material, the peroxide cross-linked polyethylene material comprises the following components in parts by weight: 1-10 parts of a peroxide cross-linked polyethylene injection molding material; the flame-retardant polyolefin composite material is prepared from the following raw materials in parts by weight: 100 parts of polyolefin resin, 2.0-10.0 parts of peroxide cross-linking agent, 0.5-0.8 part of assistant cross-linking agent, 30-60 parts of organic synergistic flame retardant, 20-50 parts of inorganic compound flame-retardant filler and 3-10 parts of functional additive. Compared with a common polyethylene material, the composite material has more excellent weather resistance and better mechanical property and ageing resistance. The problems that a traditional flame-retardant cable is poor in material mechanical property, prone to aging and the like due to the fact that too much inorganic filler is added are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of cable accessories, and more specifically to a peroxide cross-linked polyethylene injection molding compound that can be used for insulating thermoplastic skirts and its preparation method. Background Technology

[0002] As an important component of cable accessories, thermoplastic cable insulation skirts are mainly used to protect cable joints and terminals from moisture and dampness intrusion, while providing electrical insulation and mechanical protection. They play a vital role in industries such as power and communications.

[0003] With the rapid development of the power and communications industries, the performance requirements for thermoplastic cable insulation skirts are becoming increasingly stringent. Especially in extreme environments such as high temperature, high humidity, and strong electromagnetic interference, the performance of traditional thermoplastic cable insulation skirts often falls short of expectations. Traditional thermoplastic cable skirts are mostly produced using irradiation crosslinking or silane warm water crosslinking methods. These methods suffer from long production cycles, complex processing procedures, and high energy consumption. Furthermore, traditional thermoplastic cable skirts have limitations in material selection and manufacturing processes, such as poor material weather resistance, leading to unstable product performance and short service life. Therefore, a new type of thermoplastic cable skirt is urgently needed to solve the problems existing in current technologies.

[0004] Peroxide-crosslinked polyethylene (PCPE) is a material formed by adding a peroxide crosslinking agent to cause crosslinking reactions between polyethylene molecular chains, resulting in a three-dimensional network structure. This material exhibits excellent thermal stability, chemical resistance, and mechanical properties. This invention aims to significantly improve the performance of thermoplastic sheathings for cable insulation by using PCPE material and optimizing the preparation process and formulation, thereby promoting sustainable development and technological progress in the power industry and related fields. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a peroxide cross-linked polyethylene insulating umbrella skirt with high heat resistance, high mechanical strength, and resistance to environmental cracking. By introducing organic-inorganic synergistic flame retardants, peroxide cross-linking agents, and co-cross-linking agents, the overall performance of the insulating umbrella skirt is further improved, particularly its waterproofness, heat resistance, and flame retardancy.

[0006] This invention provides a peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts. The thermoplastic umbrella skirt is made of peroxide cross-linked polyethylene material, wherein the peroxide cross-linked polyethylene material, by weight, comprises the following raw materials: 100 parts of polyolefin resin, 2.0-10.0 parts of peroxide cross-linking agent, 0.5-0.8 parts of co-cross-linking agent, 30-60 parts of organic synergistic flame retardant, 20-50 parts of inorganic compound flame retardant filler, and 3-10 parts of functional additives.

[0007] Further, the polyolefin resin includes low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer and polyolefin elastomer in a mass ratio of (3.0-5.0):(0.5-2.0):(0.5-2.0):(1.2-2.4).

[0008] Furthermore, during injection molding, a cyclotriphosphazene derivative containing both 4-allyl-2-methoxyphenyl and 3-trifluoromethylphenyl is formed.

[0009] Furthermore, the organic synergistic flame retardant is a cyclotriphosphazene functional additive, whose chemical structure is characterized by containing multiple allyl and trifluoromethyl cyclotriphosphazene derivatives, with a weight ratio of 30-60 parts.

[0010] Furthermore, the chemical formula of the cyclotriphosphazene functional additive is as follows: Where m is 1, 2, 3, 4, or 5. It can be one or a mixture of several of the above structures. The optimal value is m=3, that is, a cyclotriphosphazene compound substituted with three 4-allyl-2-methoxyphenyl groups and three 3-trifluoromethylphenyl groups, with the following structure: .

[0011] Furthermore, the synthesis steps of the organic synergistic flame retardant containing allyl and trifluoromethylcyclotriphosphazene derivatives are as follows: .

[0012] Further, the peroxide crosslinking agent includes at least one of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), and benzoyl peroxide (BPO), and the amount of the peroxide crosslinking agent is 0.1% to 5% of the weight of the polyethylene resin; the co-crosslinking agent is at least one of diallyl maleate, pentaerythritol tetramethacrylate, and triallyl isocyanurate.

[0013] Furthermore, the inorganic compound flame retardant filler includes magnesium hydroxide and aluminum hydroxide in a mass ratio of (6.0-7.0):(0.5-2.0), in the amount of 20-50 parts by weight.

[0014] Furthermore, the functional additives include at least two of antioxidants, plasticizers, fillers, and lubricants. The antioxidant is at least one of alkyl biphenyl antioxidants, hydroxyphosphonate antioxidants, and hydroxyl group antioxidants. The plasticizer is at least one of dibutyl phthalate, tricresyl phosphate, and dioctyl phthalate. The lubricant is at least one of zinc stearate, stearamide, and oleamide. The total amount of the functional additives does not exceed 10% of the weight of the polyethylene resin.

[0015] This invention also provides a method for preparing peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts, comprising the following preparation steps: Step (1): Polyolefin resin, organic synergistic flame retardant, inorganic compound flame retardant filler and functional additives are mixed and processed into masterbatch semi-finished product by internal mixer; after being mixed evenly by high-speed mixer, it is granulated by parallel twin-screw extruder. Step (2): After adding peroxide crosslinking agent and co-crosslinking agent to the semi-finished masterbatch obtained in step (1), the masterbatch is then processed into masterbatch by mixing in an internal mixer. Step (3): The masterbatch is injected into the integral thermoplastic umbrella skirt mold below its vulcanization crosslinking temperature using an injection molding machine. The mold temperature is 200℃, the time is 5min, and the pressure is 10-20MPa. Step (4): Place the cross-linked heat shrinkable thermoplastic umbrella skirt obtained in step (3) into an expansion device at a temperature of 120-130℃ for 10-20 minutes to expand the diameter of the thermoplastic umbrella skirt end of the heat shrinkable thermoplastic umbrella skirt preform by 2-3 times, and cool and shape it to obtain a heat shrinkable thermoplastic umbrella skirt for cables.

[0016] Technical advantages: Compared with the prior art, the peroxide cross-linked polyethylene cable thermoplastic shed of the present invention has the following advantages: Oxide cross-linked polyethylene (OCP) injection molding compound exhibits good flowability during processing, making it easy to mold. Furthermore, its cross-linking reaction is controllable, completing under specific temperature and time conditions, thus ensuring product quality and performance. On one hand, due to the excellent weather resistance and insulation properties of OCP injection molding compound, thermoplastic sheds can remain stable in outdoor environments for extended periods, resisting aging or damage. This extends the service life of cable systems and reduces maintenance costs. On the other hand, the thermoplastic sheds adhere tightly to the cable surface and contain hydrophobic fluorinated functional components, effectively preventing the intrusion of moisture and humidity. This is crucial for protecting cables from moisture corrosion and preventing electrical faults.

[0017] The organic synergistic flame retardant in this invention is an allylcyclotriphosphazene derivative. On one hand, hexamethylenecyclotriphosphazene is rich in phosphorus and nitrogen, both of which have significant effects in the field of flame retardancy. Phosphorus promotes char formation during combustion, isolating oxygen and heat; nitrogen releases non-flammable gases, dilutes the concentration of flammable gases, reduces flame temperature, and further enhances the overall performance of cross-linked polyethylene materials, particularly their heat resistance and flame retardancy. On the other hand, during the cross-linking reaction, the peroxide cross-linking agent decomposes to generate free radicals. These free radicals can attack the polyethylene molecular chains, forming new free radicals. The allyl functional groups in the allylcyclotriphosphazene derivative can act as bridges for free radical transfer, promoting the transfer and reaction of free radicals between polyethylene molecular chains and accelerating the cross-linking process. Therefore, the introduction of the allylcyclotriphosphazene derivative may produce a synergistic effect with the polyethylene molecular chains and the cross-linking agent, making the cross-linking reaction more efficient and uniform. This synergistic effect may stem from the special chemical structure of the allylcyclotriphosphazene derivative, enabling it to form more stable chemical bonds with the polyethylene molecular chains and the cross-linking agent. Furthermore, the introduction of trifluoromethyl functional groups in cyclotriphosphazene derivatives gives peroxide crosslinked polyethylene injection molding materials better hydrophobicity and detergency.

[0018] In summary, thermoplastic umbrella skirts containing organic synergistic flame retardants are an important application of peroxide cross-linked polyethylene heat shrinkable injection molding plastics in the field of cable accessories. They not only have ideal electrical insulation, weather resistance, and waterproof and moisture-proof properties, but also enhance mechanical strength and improve heat shrinkage performance. Attached Figure Description

[0019] Figure 1 A schematic diagram of a peroxide cross-linked insulating thermoplastic umbrella skirt and its preparation method; Figure 2 Fourier transform infrared spectrum of cyclotriphosphazene derivatives, an organic synergistic flame retardant; Figure 3 The gel content spectra of the polyethylene-based composite materials in the examples (containing organic synergistic flame retardant cyclotriphosphazene derivatives) and the comparative examples (not containing organic synergistic flame retardant cyclotriphosphazene derivatives) are shown. Figure 4 The maximum tensile stress spectra of the polyethylene-based composite materials in the examples (containing organic synergistic flame retardant cyclotriphosphazene derivatives) and the comparative examples (containing no organic synergistic flame retardant cyclotriphosphazene derivatives) are shown. Figure 5 Limiting oxygen index spectra of the polyethylene-based composite materials of the examples (containing organic synergistic flame retardant cyclotriphosphazene derivatives) and the comparative examples (not containing organic synergistic flame retardant cyclotriphosphazene derivatives); Figure 6The char residue spectrum is shown for the polyethylene-based composite materials of the examples (containing organic synergistic flame retardant cyclotriphosphazene derivatives) and the comparative examples (containing no organic synergistic flame retardant cyclotriphosphazene derivatives). Detailed Implementation

[0020] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0021] It should be noted that the peroxide crosslinked polyethylene material of the present invention comprises, by weight, the following raw materials: 100 parts of polyolefin resin, 2.0-10.0 parts of peroxide crosslinking agent, 0.5-0.8 parts of co-crosslinking agent, 30-60 parts of organic synergistic flame retardant, 20-50 parts of inorganic compound flame retardant filler, and 3-10 parts of functional additives.

[0022] The polyolefin resin includes low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of (3.0-5.0):(0.5-2.0):(0.5-2.0):(1.2-2.4); the flame retardant includes magnesium hydroxide and aluminum hydroxide in a mass ratio of (6.0-7.0):(0.5-2.0).

[0023] It should also be noted that different peroxide crosslinking agent contents result in different properties of polyethylene composite materials; and polyethylene composite materials with different crosslinking temperatures also have different properties.

[0024] The present invention will be further described below with reference to embodiments: The low-density polyethylene used in the following examples is from LG Chem, and no special limitation is made here.

[0025] Example 1: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant (1) In a 1000 ml three-necked flask, 0.15 mol of 4-allyl-2-methoxyphenol (eugenol) was first dissolved in 300 ml of dry acetonitrile solvent with magnetic stirring; after stirring until fully reacted, a mixture of potassium carbonate and sodium carbonate was added as a catalyst (0.3 mol); under N2 atmosphere, the glass stopper of the middle branch of the three-necked flask was removed and a dropping funnel was placed on it; (2) Prepare 300 ml of dry acetonitrile solution containing 0.03 mol hexachlorocyclotriphosphazene; pour the prepared solution into the dropping funnel in (1) and slowly drop the solution into the reaction flask until it is finished; (3) After heating to 55℃ and reacting for 24 hours, add 0.15 mol of 3-trifluoromethylphenol to the mixed solution and react for another 24 hours.

[0026] (4) The mixture in the three-necked flask in (1) was filtered. The solid was an insoluble mixture of potassium carbonate and sodium carbonate. The precipitate was washed with acetonitrile 3-6 times. The filtrate (acetonitrile solution containing the product) was collected. The acetonitrile was removed by rotary evaporation of the filtrate to obtain a black viscous oily liquid product. After drying, it was recrystallized with ethanol. The product was a cyclotriphosphazene containing both (4-allyl-2-methoxyphenyl) and 3-trifluoromethylphenyl, with a yield of 72.3%.

[0027] This embodiment provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 50 parts of organic synergistic flame retardant, 10 parts of inorganic compound flame retardant filler, and 8 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 3:1:1:1.2; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:1; the peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is antioxidant 1010; the lubricant is zinc stearate; and the plasticizer is dibutyl phthalate.

[0028] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment includes the following steps: (1) The raw materials are mixed and processed into masterbatch semi-finished products by internal mixer according to the formula; after being mixed evenly by high-speed mixer, they are granulated by parallel twin-screw extruder. (2) After adding the main crosslinking agent and the auxiliary crosslinking agent to the semi-finished masterbatch obtained in step (1), it is then processed into masterbatch by mixing in an internal mixer; (3) The masterbatch is injected into the integral thermoplastic umbrella skirt mold below its vulcanization crosslinking temperature by injection molding machine. The mold temperature is 200℃, the time is 5min, and the pressure is 10-20MPa. (4) Place the cross-linked heat shrinkable thermoplastic umbrella skirt obtained in step (3) into an expansion device at a temperature of 120-130℃ for 10-20 minutes to expand the diameter of the thermoplastic umbrella skirt end of the heat shrinkable thermoplastic umbrella skirt preform by 2-3 times, and cool and shape to obtain a heat shrinkable thermoplastic umbrella skirt for cables.

[0029] Example 2: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant (1) In a 1000 ml three-necked flask, first dissolve 0.10 mol of eugenol in 300 ml of dry acetonitrile solvent with magnetic stirring; after stirring to react fully, add a mixture of potassium carbonate and sodium carbonate as catalyst (0.15 mol each); under N2 atmosphere, remove the glass stopper of the middle branch of the three-necked flask and place a dropping funnel on it; (2) Prepare 300 ml of dry acetonitrile solution containing 0.05 mol hexachlorocyclotriphosphazene; pour the prepared solution into the dropping funnel in (1) and slowly drop the solution into the reaction flask until it is finished; (3) After heating to 55℃ and reacting for 24 hours, add 0.20 mol of 3-trifluoromethylphenol to the mixed solution and react for another 24 hours. (4) The mixture in the three-necked flask in (1) was filtered and purified (the specific steps were the same as in Example 1). The product was a cyclotriphosphazene with (4-allyl-2-methoxyphenyl) and 3-trifluoromethylphenyl, with a yield of 71.6%.

[0030] This embodiment provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 50 parts of organic synergistic flame retardant (prepared according to the above method), 10 parts of inorganic compound flame retardant filler, and 8 parts of functional additives; the specific composition is the same as in Example 1.

[0031] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment is the same as that in Example 1.

[0032] Example 3: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant. The specific steps are the same as in Example 2.

[0033] This embodiment provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 50 parts of organic synergistic flame retardant (prepared according to the steps of Example 2), 10 parts of inorganic compound flame retardant filler, and 7 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 4:1.5:1.5:1.8; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:0.8; the peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is an alkyl biphenyl antioxidant; the lubricant is zinc stearate; and the plasticizer is tricresyl phosphate.

[0034] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment is the same as that in Example 1.

[0035] Example 4: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant (1) In a 1000 ml three-necked flask, first dissolve 0.05 mol of eugenol in 300 ml of dry acetonitrile solvent with magnetic stirring; after stirring to react fully, add a mixture of potassium carbonate and sodium carbonate as catalyst (0.15 mol each); under N2 atmosphere, remove the glass stopper of the middle branch of the three-necked flask and place a dropping funnel on it. (2) Prepare 300 ml of dry acetonitrile solution containing 0.05 mol hexachlorocyclotriphosphazene; pour the prepared solution into the dropping funnel in (1) and slowly drop the solution into the reaction flask until it is finished; (3) After heating to 55℃ and reacting for 24 hours, add 0.25 mol of 3-trifluoromethylphenol to the mixed solution and react for another 24 hours. (4) The mixture in the three-necked flask in (1) was filtered and purified (the specific steps were the same as in Example 1) and the product was a cyclotriphosphazene with (4-allyl-2-methoxyphenyl) and 3-trifluoromethylphenyl, with a yield of 70.8%.

[0036] This experimental example provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 20 parts of organic synergistic flame retardant (prepared according to the above method), 40 parts of inorganic compound flame retardant filler, and 7 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 4:1.5:1.5:1.8; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:0.8; the peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is an alkyl biphenyl antioxidant; the lubricant is zinc stearate; and the plasticizer is tricresyl phosphate.

[0037] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment is the same as that in Example 1.

[0038] Example 5: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant. The specific steps are the same as in Example 4.

[0039] This embodiment provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 50 parts of organic synergistic flame retardant (prepared according to the method of Example 4), 10 parts of inorganic compound flame retardant filler, and 5 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 5:2:2:2.2; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:1.2; the peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is a hydroxyphosphonate antioxidant; the lubricant is calcium stearate; and the plasticizer is dioctyl phthalate.

[0040] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment is the same as that in Example 1.

[0041] Example 6: Preparation of a trifluoromethyl-allyl bifunctionalized cyclotriphosphazene synergistic flame retardant (1) In a 1000 ml three-necked flask, first dissolve 0.05 mol of eugenol in 300 ml of dry acetonitrile solvent with magnetic stirring; after stirring to react fully, add a mixture of potassium carbonate and sodium carbonate as catalyst (0.15 mol each); under N2 atmosphere, remove the glass stopper of the middle branch of the three-necked flask and place a dropping funnel on it. (2) Prepare 300 ml of dry acetonitrile solution containing 0.05 mol hexachlorocyclotriphosphazene; pour the prepared solution into the dropping funnel in (1) and slowly drop the solution into the reaction flask until it is finished; (3) After heating to 55℃ and reacting for 24 hours, add 0.28 mol of 3-trifluoromethylphenol to the mixed solution and react for another 24 hours. (4) The mixture in the three-necked flask in (1) was filtered and purified (the specific steps were the same as in Example 1) and the product was a cyclotriphosphazene with (4-allyl-2-methoxyphenyl) and 3-trifluoromethylphenyl, with a yield of 68.2%.

[0042] This experimental example provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 20 parts of organic synergistic flame retardant (prepared according to the above method), 40 parts of inorganic compound flame retardant filler, and 5 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 5:2:2:2.2; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:1.2; the peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is a hydroxyphosphonate antioxidant; the lubricant is calcium stearate; and the plasticizer is dioctyl phthalate.

[0043] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this embodiment is the same as that in Example 1.

[0044] Comparative Example 1 This comparative example provides a peroxide crosslinked insulating thermoplastic umbrella skirt, comprising the following materials in parts by weight: 100 parts of polyolefin resin, 8 parts of peroxide crosslinking agent, 0.8 parts of co-crosslinking agent, 60 parts of inorganic compound flame retardant filler, and 5 parts of functional additives; wherein, the polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of 5:2:2:2.2; the inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of 6:1.2.

[0045] The peroxide crosslinking agent is dicumyl peroxide; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is a hydroxyphosphonate antioxidant; the lubricant is calcium stearate; and the plasticizer is dioctyl phthalate.

[0046] The preparation method of the peroxide cross-linked insulating thermoplastic umbrella skirt in this comparative example is the same as that in Example 1.

[0047] The performance of peroxide crosslinked insulating thermoplastic umbrella skirts prepared in Examples 1-6 with added organic synergistic flame retardants and Comparative Example 1 without added organic synergistic flame retardants was investigated.

[0048] Table 1. Performance of cross-linked polyethylene composite flame-retardant cable insulation material (containing organic synergistic flame retardant cyclotriphosphazene derivatives).

[0049] .

[0050] Table 2 Performance of cross-linked polyethylene composite flame-retardant cable insulation material (excluding organic synergistic flame retardant cyclotriphosphazene derivatives).

[0051] .

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts, characterized in that, The thermoplastic umbrella skirt is made of peroxide cross-linked polyethylene material, wherein the peroxide cross-linked polyethylene material, by weight, comprises the following raw materials: 100 parts of polyolefin resin, 2.0-10.0 parts of peroxide cross-linking agent, 0.5-0.8 parts of co-cross-linking agent, 30-60 parts of organic synergistic flame retardant, 20-50 parts of inorganic compound flame retardant filler, and 3-10 parts of functional additives.

2. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 1, characterized in that, The polyolefin resin comprises low-density polyethylene, ethylene propylene diene monomer (EPDM) rubber, ethylene-vinyl acetate copolymer, and polyolefin elastomer in a mass ratio of (3.0-5.0):(0.5-2.0):(0.5-2.0):(1.2-2.4).

3. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 1, characterized in that, The injection molding compound contains cyclotriphosphazene derivative functional additives containing 4-allyl-2-methoxyphenyl and 3-trifluoromethylphenyl.

4. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 3, characterized in that, The organic synergistic flame retardant is a cyclotriphosphazene functional additive, characterized by a chemical structure containing multiple allyl and trifluoromethyl cyclotriphosphazene derivatives, with a weight ratio of 30-60 parts.

5. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 4, characterized in that, The chemical formula of the cyclotriphosphazene functional additive is as follows: , where m is 1, 2, 3, 4 or 5.

6. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 5, characterized in that, The synthesis steps of the organic synergistic flame retardant containing allyl and trifluoromethylcyclotriphosphazene derivatives are as follows: 。 7. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 1, characterized in that, The peroxide crosslinking agent includes at least one of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), and benzoyl peroxide (BPO), and the amount of the peroxide crosslinking agent is 0.1% to 5% of the weight of the polyethylene resin; the co-crosslinking agent is at least one of diallyl bismaleate, pentaerythritol tetramethacrylate, and triallyl isocyanurate.

8. The peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 1, characterized in that, The inorganic compound flame retardant filler comprises magnesium hydroxide and aluminum hydroxide in a mass ratio of (6.0-7.0):(0.5-2.0), in a weight ratio of 20-50 parts.

9. A peroxide cross-linked polyethylene injection molding compound for thermoplastic umbrella skirts according to claim 1, characterized in that, The functional additives include at least two of the following: antioxidants, plasticizers, fillers, and lubricants. The antioxidant is at least one of alkyl biphenyl antioxidants, hydroxyphosphonate antioxidants, and hydroxyl group antioxidants. The plasticizer is at least one of dibutyl phthalate, tricresyl phosphate, and dioctyl phthalate. The lubricant is at least one of zinc stearate, stearamide, and oleamide. The total amount of the functional additives does not exceed 10% of the weight of the polyethylene resin.

10. A method for preparing peroxide-crosslinked polyethylene injection molding compound for thermoplastic umbrella skirts, for preparing a peroxide-crosslinked polyethylene injection molding compound for thermoplastic umbrella skirts as described in any one of claims 1-9, characterized in that, The preparation steps include the following: Step (1): Polyolefin resin, organic synergistic flame retardant, inorganic compound flame retardant filler and functional additives are mixed and processed into masterbatch semi-finished product by internal mixer; after being mixed evenly by high-speed mixer, it is granulated by parallel twin-screw extruder. Step (2): After adding peroxide crosslinking agent and co-crosslinking agent to the semi-finished masterbatch obtained in step (1), the masterbatch is then processed into masterbatch by mixing in an internal mixer. Step (3): The masterbatch is injected into the integral thermoplastic umbrella skirt mold below its vulcanization crosslinking temperature using an injection molding machine. The mold temperature is 200℃, the time is 5min, and the pressure is 10-20MPa. Step (4): Place the cross-linked heat shrinkable thermoplastic umbrella skirt obtained in step (3) into an expansion device at a temperature of 120-130℃ for 10-20 minutes to expand the diameter of the thermoplastic umbrella skirt end of the heat shrinkable thermoplastic umbrella skirt preform by 2-3 times, and cool and shape it to obtain a heat shrinkable thermoplastic umbrella skirt for cables.

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