A flame retardant communication power sheath pipe and a preparation method thereof

Abstract

The application discloses a kind of flame-retardant communication power sheath pipe and preparation method thereof, belong to sheath pipe technical field, the flame-retardant communication power sheath pipe includes the following mass fraction of raw materials: block copolymerized polypropylene 15~40 parts, high-density polyethylene 20~50 parts, heat-resistant polyethylene 0~10 parts, compound flame-retardant powder 25~35 parts, compatibility agent 0.1~1 parts, antioxidant 0.1~0.8 parts, coupling agent 1~3 parts and dispersing agent 0.5~2 parts, compound flame-retardant powder includes piperazine pyrophosphate and / or melamine polyphosphate.Block copolymerized polypropylene and high-density polyethylene blend, can make up the loss of tensile yield strength caused by excessive powder, also can better promote the formation of carbon layer, heat-resistant polyethylene can form interpenetrating structure between the molecular network formed by composite material, effectively improve the compactness of composite material, so as to improve the oxygen index of composite material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sheath pipes, and particularly relates to a flame-retardant communication power sheath pipe and a preparation method thereof. BACKGROUND

[0002] The communication power sheath pipe is an external structure for protecting cables, which is made of various materials and has the functions of insulation, protection and cable fixation. The sheath pipe is widely used in the fields of power and communication and can ensure the safety and reliability of cables in various environments.

[0003] The existing communication power sheath pipes are mainly plastic pipes, and the PVC (polyvinyl chloride) pipe is the main one. However, compared with the PVC pipe, the PE (polyethylene) pipe and the PP (polypropylene) pipe have more excellent properties, such as corrosion resistance, good flexibility and low-temperature resistance, and have the advantages of long service life, low production energy consumption, small water flow resistance, easy installation and disassembly, etc. in the actual application process, and are expected to become a pipe material that can replace the PVC pipe and be used more widely. At present, the high-density polyethylene pipe has been widely used in communication power sheath pipes and has become one of the materials that are difficult to replace the PVC pipe in the non-excavation field.

[0004] However, when the PE pipe and the PP pipe are used as communication power sheath pipes, there is a problem of poor flame retardance. Since the polyethylene and polypropylene materials are both flammable polymers and have a low oxygen index, the pipe materials prepared from the polyethylene and polypropylene generally have poor flame retardance. In order to improve the safety of the pipe materials as communication power sheath pipes, it is necessary to improve the flame retardance of the pipe materials.

[0005] At present, the method for improving the flame retardance of the PP pipe and the PE pipe is to add a bromine-based composite flame retardant or a halogen-free flame retardant during the preparation process. The bromine-based flame retardant is not environmentally friendly and has relatively large toxicity. The halogen-free flame retardant needs to be added in a large amount to achieve a certain flame retardant effect, and the flame retardant grade is not high, which is difficult to reach the V0 level. Moreover, a large amount of addition of the halogen-free flame retardant causes a significant decrease in the mechanical properties of the pipe materials, which cannot meet the application of the pipe materials in the non-excavation field. SUMMARY

[0006] The purpose of the present application is to provide a flame-retardant communication power sheath pipe and a preparation method thereof, so as to solve the problems of poor flame retardance and difficult to balance the flame retardance and mechanical properties of the polyolefin pipe.

[0007] The purpose of the present application can be achieved by the following technical scheme.

[0008] In a first aspect, the present application provides a flame-retardant communication power sheath pipe, which comprises the following raw materials in mass fractions:

[0009] 15-40 parts of block copolymerized polypropylene;

[0010] High-density polyethylene 20-50 parts;

[0011] Heat-resistant polyethylene 0-10 parts;

[0012] Compound flame-retardant powder 25-35 parts;

[0013] Compatibility agent 0.1-1 part;

[0014] Antioxidant 0.1-0.8 part;

[0015] Coupling agent 1-3 parts;

[0016] Dispersant 0.5-2 parts;

[0017] The compound flame-retardant powder comprises piperazine pyrophosphate and / or melamine polyphosphate.

[0018] Preferably, the block copolymerized polypropylene has a melt index ≤ 0.8 g / 10 min, a tensile yield strength ≥ 25 MPa, and a flexural modulus ≥ 1500 MPa.

[0019] Preferably, the compatibility agent comprises a combination of one or more of SEBS grafted maleic anhydride, PP grafted maleic anhydride, and PE grafted maleic anhydride.

[0020] Preferably, the antioxidant comprises a combination of one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 245, antioxidant 1098, and antioxidant 626.

[0021] Preferably, the coupling agent comprises any one of a silane coupling agent and a titanate coupling agent.

[0022] More preferably, the silane coupling agent comprises a combination of one or more of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, γ-methacryloxypropyl trimethoxysilane, and N-(2-aminoethyl)-3-aminopropyl triethoxysilane.

[0023] More preferably, the titanate coupling agent comprises a combination of one or more of isopropyl tri(dodecylbenzenesulfonyl) titanate, triisostearyl titanate, and isopropyl tri(dioctylpyrophosphato) titanate.

[0024] Preferably, the dispersant comprises a combination of one or more of polyethylene wax, calcium stearate, zinc stearate, butyl stearate, and vinyl bis-stearamide.

[0025] By adopting the technical scheme, the application selects pyrophosphoric acid piperazine and / or melamine polyphosphate as the main flame retardant component, the pyrophosphoric acid piperazine and the melamine polyphosphate can promote the charring reaction at high temperature, generate a dense carbon layer on the surface of the polymer, and when heated, the high-temperature decomposition generates gas, so that the carbon layer expands rapidly, thereby insulating oxygen and heat, as a physical barrier, the temperature of the material surface can be further reduced, the evaporation of flammable gas is reduced, and the effect of extinguishing the flame is achieved. The piperazine part in the pyrophosphoric acid piperazine can also capture active free radicals during combustion, interrupt the combustion chain reaction, and reduce the combustion speed, which is crucial for slowing down the flame propagation.

[0026] However, like many halogen-free flame retardants, pyrophosphoric acid piperazine and melamine polyphosphate must be added in sufficient quantity to achieve good flame retardant effect, and excessive addition will inevitably lead to a significant decrease in the mechanical properties of the material. In order to improve this problem, the application uses block copolymerized polypropylene and high-density polyethylene for compounding, wherein the block copolymerized polypropylene has a higher proportion of ethylene component compared to homopolymerized polypropylene, has better impact resistance, and at the same time maintains a certain degree of rigidity, while the high-density polyethylene has excellent flexibility, the combination of the two can significantly improve the impact strength and elongation at break of the composite material, thereby making up for the loss of tensile yield strength caused by excessive flame retardant powder.

[0027] Moreover, the high-density polyethylene has high thermal stability and can maintain good physical and chemical properties at high temperatures, which promotes the overall flame retardant performance of the material, and the blending of block copolymerized polypropylene and high-density polyethylene can help disperse the compounded flame retardant powder and promote the formation of a more uniform carbon layer, further improving the flame retardant performance and oxygen index of the material.

[0028] In order to improve the compatibility between the block copolymerized polypropylene and the high-density polyethylene, a compatibilizer is also added to the system, which can reduce the interfacial tension and make the two polymers interact better, thereby optimizing the dispersion of the compounded flame retardant powder in the system. Good dispersion can improve the mechanical properties of the material. In order to further improve the interfacial interaction between the polymer and the compounded flame retardant powder, a coupling agent is also added, which can effectively reduce the agglomeration of the powder, resulting in a uniform microstructure of the composite material, which can better disperse stress and thereby improve the mechanical properties of the material. Moreover, the addition of the coupling agent can promote the formation of a carbon layer during combustion, help insulate oxygen, prevent the spread of flames, slow down the temperature rise, further improve the flame retardant performance of the material, and ultimately obtain a pipe material with excellent comprehensive performance.

[0029] Preferably, the compounded flame-retardant powder further comprises a flame-retardant synergist; the flame-retardant synergist comprises a combination of one or more of aluminum diethylphosphinate, inorganic aluminum hypophosphite and pentaerythritol.

[0030] Preferably, the addition amount of the flame-retardant synergist is 1-3% of the total mass of the compounded flame-retardant powder.

[0031] By adopting the above technical solution, in order to further improve the flame-retardant performance of the composite material, the compounded flame-retardant powder further comprises a flame-retardant synergist, which can decompose non-flammable gas at the initial stage of combustion and form a flame-retardant layer to protect the substrate from more serious pyrolysis, and can also increase the mass and density of the carbon layer formed by the flame retardant, provide additional heat resistance and anti-dripping performance, produce a synergistic effect, form a more effective flame-retardant system, and achieve better flame-retardant standards.

[0032] Preferably, the heat-resistant polyethylene comprises a combination of one or more of ethylene-1-butene copolymer, ethylene-1-hexene copolymer and ethylene-octene copolymer.

[0033] More preferably, the mass fraction of the heat-resistant polyethylene is 6-9 parts.

[0034] By adopting the above technical solution, the present application further adds heat-resistant polyethylene to the composite material in order to further improve the flame-retardant performance and mechanical performance of the composite material. Specifically, the heat-resistant polyethylene is a random copolymer composed of ethylene and high-carbon alpha-olefins such as butene, hexene and octene, which contains a certain proportion of long-chain branched structure, can form a mixture of semi-crystalline regions and non-crystalline regions at the micro level, can help improve the strength while improving the flexibility of the material, can maintain certain physical properties at high temperatures, and when high-carbon alpha-olefins are introduced as comonomers into the ethylene backbone, longer side chain branches are formed, which can help increase the entanglement density between molecules and maintain a relatively stable morphology in a high-temperature environment, and has good heat resistance.

[0035] This structural feature can form a micro-phase separation structure in the composite material, which can effectively disperse stress and improve the mechanical properties of the material, and copolymerization with ethylene can also improve its compatibility in the material system of the present application, and the interfacial force is improved.

[0036] Moreover, the addition of heat-resistant polyethylene can form an interpenetrating structure between the molecular network formed by the block copolymerization of polypropylene and high-density polyethylene, and the crystalline part can interact with the polyethylene and polypropylene matrix, thereby effectively improving the compactness of the composite material and effectively improving the oxygen index of the composite material. The presence of heat-resistant polyethylene also helps to promote the formation of a more compact and stable carbon layer under heat conditions, helps to insulate the flame and oxygen, reduces the transfer of heat, effectively inhibits the spread of fire, and thus improves the flame-retardant performance of the composite material.

[0037] Preferably, the raw materials further include 3-5 parts by mass of microcrystalline layered muscovite.

[0038] Preferably, the microcrystalline layered muscovite has a particle size of 400-600 mesh.

[0039] By adopting the technical scheme, under the compounding effect of the block copolymerized polypropylene and the high-density polyethylene, the tensile yield strength loss caused by the compounding flame-retardant powder can be effectively compensated, but the effect of improving the oxygen index of the composite material is limited, and as a main component of the compounding flame-retardant powder, pyrophosphoric acid piperazine is a strong polar compound and is easy to hydrolyze and precipitate during the forming process, thereby affecting the flame retardancy of the material.

[0040] To further improve the performance of the material, the microcrystalline layered muscovite is further added to the composite material, and the coupling agent and the compatilizer in the composite material can also help the microcrystalline layered muscovite to be uniformly dispersed in the composite material, so as to form one or more nanoscale lamellar structures inside the polypropylene and polyethylene composite material, which can effectively hinder the transmission path of oxygen, heat and flammable gas in the material, thereby delaying the speed of flame spread and improving the overall oxygen index of the material, and the aluminum silicate component in the microcrystalline layered muscovite can play a certain catalytic role at high temperature, helping to generate more non-combustible carbon residues, which helps to build a more dense and stable carbon layer and increase the flame retardancy of the material.

[0041] The nanoscale physical barrier formed by the microcrystalline layered muscovite in the composite material can also directly reduce the opportunity of water contacting the compounding flame-retardant powder, effectively prevent water from entering, thereby reducing the risk of hydrolysis, and the metal cations contained in the microcrystalline layered muscovite interact with the pyrophosphoric acid piperazine, thereby improving the stability of the compounding flame-retardant powder through electrostatic attraction and chemical bonding, and improving the hydrolysis resistance of the composite material.

[0042] In addition, the addition of the microcrystalline layered muscovite can also help to maintain and improve the mechanical properties of the material and improve the processability, so that the material is easier to form.

[0043] In a second aspect, the present application provides a preparation method of a flame-retardant communication power sheath pipe, comprising the following process steps:

[0044] S1. The dispersing agent and the coupling agent are sequentially added to the compounding flame-retardant powder, and after being uniformly mixed, the block copolymerized polypropylene and the high-density polyethylene are added and stirred to obtain a premix;

[0045] S2. The compatilizer, the microcrystalline layered muscovite and the heat-resistant polyethylene are sequentially added to the premix, and after being stirred and mixed, the flame-retardant communication power sheath pipe is obtained through melt extrusion, cooling and shaping and traction cutting.

[0046] Preferably, the technical problem of the present application can also be solved without adding microcrystalline layered muscovite in the S2 step.

[0047] Preferably, in the S1 step, the premix is first melted and extruded to obtain premix masterbatch, and then the premix masterbatch, the compatibilizer, the microcrystalline layered muscovite and the heat-resistant polyethylene are stirred and mixed, and then the mixture is subjected to melt extrusion, cooling and shaping and traction cutting to obtain the flame-retardant communication power sheath pipe.

[0048] By adopting the above technical scheme, in order to further improve the dispersibility between the compounded flame-retardant powder and the polymer base material, part of the polymer and the compounded flame-retardant powder can be mixed to form a masterbatch, and then the remaining materials are mixed and extruded, which is beneficial to processing and improves the performance of the material.

[0049] The beneficial effects of the present application are as follows:

[0050] 1. The flame-retardant communication power sheath pipe of the present application is used to improve the mechanical properties of the high-addition flame-retardant powder system by using the blending mode of block copolymerized polypropylene and high-density polyethylene, which can improve the impact resistance of the material while maintaining good rigidity, make up for the loss of tensile yield strength caused by excessive powder, and better promote the formation of a carbon layer to improve the flame-retardant properties and oxygen index of the material. In order to further improve the performance of the material, heat-resistant polyethylene is added to the composite material to form a penetrating structure between the molecular network formed by the block copolymerized polypropylene and high-density polyethylene composite material, and the crystalline part can interact with the polyethylene and polypropylene matrix, thereby effectively improving the compactness of the composite material and the oxygen index of the composite material.

[0051] 2. The flame-retardant communication power sheath pipe of the present application further adds microcrystalline layered muscovite, which can form one or more nanoscale lamellar structures inside the polypropylene and polyethylene composite material. These lamellar structures can effectively block the transmission path of oxygen, heat and flammable gas inside the material, improve the oxygen index of the material, effectively prevent moisture from entering, reduce the hydrolysis and easy precipitation of the compounded flame-retardant powder, and finally help maintain and improve the mechanical properties of the material and improve the processability, making the material easier to shape. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0053] Embodiment

[0054] Example 1, a flame-retardant communication power sheath pipe, is prepared according to the following process steps:

[0055] S1. 0.1 kg of calcium stearate, 0.05 kg of antioxidant 1010 and 0.2 kg of γ-aminopropyl triethoxysilane are sequentially added to 3 kg of a compounded flame-retardant powder, wherein the compounded flame-retardant powder comprises a mixture of 98% of piperazine pyrophosphate and melamine polyphosphate and 2% of aluminum diethylphosphinate, the mass ratio of piperazine pyrophosphate and melamine polyphosphate being 2:1, after being uniformly mixed, 2.5 kg of block copolymerized polypropylene (melt index being 0.6 g / 10 min) and 3.2 kg of high-density polyethylene (melt index being 30 g / 10 min) are added, and stirring and mixing are performed to obtain a premix;

[0056] S2. 0.1 kg of SEBS grafted maleic anhydride and 0.8 kg of ethylene-1-butene copolymer are sequentially added to the premix, after stirring and mixing, melt extrusion, cooling and setting and traction cutting are performed to obtain the flame-retardant communication power sheath pipe.

[0057] Examples 2-4, a flame-retardant communication power sheath pipe, differ from Example 1 only in that the raw material ratio is adjusted, and the specific embodiments are shown in Table 1:

[0058] Table 1, the formula table of Examples 1-4

[0059] Example 1 Example 2 Example 3 Example 4 Block copolymerized polypropylene / kg 2.5 1.5 3.5 2.0 High density polyethylene / kg 3.2 4.0 2.2 4.0 Ethylene-1-butene copolymer / kg 0.8 / 0.8 0.7 Compound flame-retardant powder / kg 3.0 3.0 3.0 2.7 SEBS grafted maleic anhydride / kg 0.1 0.1 0.1 0.1 Antioxidant 1010 / kg 0.05 0.05 0.05 0.05 Gamma-aminopropyl triethoxysilane / kg 0.2 0.2 0.25 0.15 Calcium stearate / kg 0.1 0.1 0.1 0.1

[0060] The compounded flame-retardant powder in Examples 2-4 is a mixture of 98% of piperazine pyrophosphate and melamine polyphosphate and 2% of aluminum diethylphosphinate, wherein the mass ratio of piperazine pyrophosphate and melamine polyphosphate is 2:1.

[0061] Example 5, a flame-retardant communication power sheath pipe, differs from Example 1 only in that the compounded flame-retardant powder is 98% of piperazine pyrophosphate and 2% of aluminum diethylphosphinate.

[0062] Example 6, a flame-retardant communication power sheath pipe, differs from Example 1 only in that the compounded flame-retardant powder is 98% of melamine polyphosphate and 2% of aluminum diethylphosphinate.

[0063] Example 7, a flame-retardant communication power sheath pipe, differs from Example 1 only in that an equal amount of isopropyl tri(dodecylbenzenesulfonyl) titanate is used to replace γ-aminopropyl triethoxysilane.

[0064] Example 8, a flame-retardant communication power sheath pipe, which is different from example 1 only in that the ethylene-1-butene copolymer is replaced by an equal amount of ethylene-1-octene copolymer.

[0065] Example 9, a flame-retardant communication power sheath pipe, which is prepared according to the following process steps:

[0066] S1. Add 0.1 kg of calcium stearate, 0.05 kg of antioxidant 1010 and 0.2 kg of γ-aminopropyl triethoxysilane into 3 kg of a compounded flame-retardant powder in sequence, wherein the compounded flame-retardant powder comprises a mixture of 98% of piperazine pyrophosphate and melamine polyphosphate and 2% of aluminum diethyl hypophosphite, and the mass ratio of piperazine pyrophosphate to melamine polyphosphate is 2:1, then add 2.5 kg of block copolymerized polypropylene (melt index is 0.6 g / 10 min) and 3.2 kg of high-density polyethylene (melt index is 30 g / 10 min) after uniform mixing, and stir and mix to obtain a premix, and melt extrude and granulate the premix to obtain a premix masterbatch;

[0067] S2. Add 0.1 kg of SEBS grafted maleic anhydride and 0.8 kg of ethylene-1-butene copolymer into the premix masterbatch in sequence, and stir and mix after mixing, and then melt extrude, cool and shape, and draw and cut to obtain the flame-retardant communication power sheath pipe.

[0068] Example 10, a flame-retardant communication power sheath pipe, which is different from example 1 only in that the compounded flame-retardant powder is a mixture of piperazine pyrophosphate and melamine polyphosphate, and the mass ratio of piperazine pyrophosphate to melamine polyphosphate is 2:1.

[0069] Example 11, a flame-retardant communication power sheath pipe, which is different from example 1 only in that 0.4 kg of microcrystalline layered muscovite (average particle size is 400 mesh) is further added in the S2 step.

[0070] Example 12, a flame-retardant communication power sheath pipe, which is different from example 11 only in that the addition amount of microcrystalline layered muscovite is 0.3 kg.

[0071] Example 13, a flame-retardant communication power sheath pipe, which is different from example 11 only in that the addition amount of microcrystalline layered muscovite is 0.5 kg.

[0072] Example 14, a flame-retardant communication power sheath pipe, which is different from example 11 only in that the addition amount of microcrystalline layered muscovite is 0.1 kg.

[0073] Example 15, a flame-retardant communication power sheath pipe, which is different from example 11 only in that the addition amount of microcrystalline layered muscovite is 0.7 kg.

[0074] Example 16, a flame-retardant communication power sheath pipe material, differs from Example 11 only in that the microcrystalline stratified white mica is replaced with an equal amount of white mica with an average particle size of 800 mesh.

[0075] Comparative Example

[0076] Comparative Example 1, a flame-retardant communication power sheath pipe material, differs from Example 1 only in that the block copolymer polypropylene is replaced with an equal amount of homopolymer polypropylene.

[0077] Comparative Example 2, a flame-retardant communication power sheath pipe material, differs from Example 1 only in that the high-density polyethylene is replaced with an equal amount of medium-density polyethylene.

[0078] Comparative Example 3, a flame-retardant communication power sheath pipe material, differs from Example 1 only in that the amount of ethylene-1-butene copolymer added is 1.2 kg.

[0079] Performance Test Test

[0080] 1. Flame-retardant performance test:

[0081] (1) Flame-retardant grade: According to the relevant records in GB / T 2408-2021 “Determination of the Burning Behavior of Plastics Horizontal and Vertical Methods”, the vertical burning flame-retardant grade of the flame-retardant communication power sheath pipe material obtained in the examples and comparative examples is tested.

[0082] (2) Oxygen index: According to the relevant records in GB / T 2406.2-2009 “Determination of the Burning Behavior of Plastics by the Oxygen Index Method Part 2: Room Temperature Test”, the oxygen index of the flame-retardant communication power sheath pipe material obtained in the examples and comparative examples is tested.

[0083] 2. Mechanical performance test: According to the relevant records in GB / T 1040.1-2018 “Determination of the Tensile Properties of Plastics Part 1: General Principles”, the tensile yield strength and elongation at break of the flame-retardant communication power sheath pipe material obtained in the examples and comparative examples are tested.

[0084] The test results are shown in Table 2:

[0085] Table 2 Performance Test Test Results

[0086]

[0087]

[0088] According to Table II, combined with Example 1 and Example 9, it can be seen that the mechanical properties of Example 9 are slightly improved compared with Example 1, because in Example 9, the two-step method is used for preparation, first melt extrusion to obtain a premix masterbatch, and then mixed with other components for extrusion, so that the dispersion of the composite material is better, which can improve the mechanical properties of the material to a certain extent.

[0089] Combined with Example 1 and Example 10, it can be seen that the flame retardant grade of Example 10 decreases, because in Example 10, no flame retardant synergist is added in the compounded flame retardant powder, which will increase the influence of pyrolysis on the substrate in the early stage of heating, and also cannot help the flame retardant to improve the quality and density of the carbon layer formed, so as to produce a synergistic effect, thereby causing the flame retardant performance to decrease.

[0090] Combined with Example 1 and Example 11, it can be seen that the oxygen index and tensile yield strength of Example 11 increase compared with Example 1, because the difference between Example 11 and Example 1 is only that microcrystalline layered muscovite is added, the addition of microcrystalline layered muscovite can form one or more layers of nanoscale lamellar structure inside the material, which can effectively hinder the transmission path of oxygen, heat and flammable gas inside the material, improve the oxygen index of the material, and also effectively prevent moisture from entering, reduce the problem of hydrolysis and easy precipitation of the compounded flame retardant powder, and effectively maintain and improve the mechanical properties of the material.

[0091] Combined with Example 11 and Example 16, it can be seen that the oxygen index and tensile yield strength of Example 16 decrease compared with Example 11, because the particle size of the muscovite added in Example 16 is large, the dispersibility in the material decreases, and the specific surface area decreases significantly, which can cause debonding phenomenon, thereby reducing the mechanical properties of the material.

[0092] Combined with Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the flame retardant performance and mechanical properties of Comparative Example 1 and Comparative Example 2 decrease compared with Example 1, because in Comparative Example 1, no block copolymerized polypropylene is used, and in Comparative Example 2, no high-density polyethylene is used. The impact strength of homopolymer polypropylene is lower than that of block copolymerized polypropylene, and it is difficult to form an intermolecular entanglement structure with polyethylene, which leads to a decrease in the density of the material inside, thereby causing the performance of the obtained composite material to decrease; the flexibility of medium-density polyethylene decreases compared with high-density polyethylene, and the strength also decreases, which cannot compensate for the loss of tensile yield strength caused by excessive flame retardant powder.

[0093] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and illustrative figures, it should be apparent that the scope of the present application is not limited to these specific embodiments.

[0094] While the embodiments of the application have been shown and described herein, it will be understood by those skilled in the art that many changes, modifications, substitutions and alterations to these embodiments can be made without departing from the principles and spirits of the application, and it is intended that the scope of the application be limited solely by the scope of the appended claims and the equivalents thereof.

Claims

1. A flame retardant communication power sheath pipe, characterized by, The raw materials include the following mass fractions: Block copolymerized polypropylene 15-40 parts; High-density polyethylene 20-50 parts; Heat-resistant polyethylene 0-6 parts; Compound flame-retardant powder 25-35 parts; Compatibility agent 0.1-1 part; Antioxidant 0.1-0.8 part; Coupling agent 1-3 parts; Dispersant 0.5-2 parts; The compound flame-retardant powder includes piperazine pyrophosphate and / or melamine polyphosphate; The heat-resistant polyethylene includes a combination of one or more of ethylene-1-butene copolymer, ethylene-1-hexene copolymer and ethylene-octene copolymer; The raw materials further include 3-5 parts by mass of microcrystalline layered white mica; the particle size of the microcrystalline layered white mica is 400-600 mesh.

2. The flame retardant communication power sheath tube of claim 1, wherein, The compound flame-retardant powder further includes a flame-retardant synergist; the flame-retardant synergist includes a combination of one or more of aluminum diethyl hypophosphite, inorganic aluminum hypophosphite and pentaerythritol.

3. The flame retardant communication power sheath tube of claim 2, wherein, The addition amount of the flame-retardant synergist is 1-3% of the total mass of the compound flame-retardant powder.

4. The flame retardant communication power sheath tube of claim 1, wherein, The coupling agent includes any one of silane coupling agent and titanate coupling agent.

5. The flame retardant communication power sheath tube of claim 1, wherein, The compatibility agent includes a combination of one or more of SEBS grafted maleic anhydride, PP grafted maleic anhydride and PE grafted maleic anhydride.

6. A method of producing a flame retardant communication power sheath pipe according to any one of claims 1 to 5, characterized by, The process includes the following steps: S1. The dispersant, antioxidant and coupling agent are sequentially added to the compound flame-retardant powder, and after being uniformly mixed, the block copolymerized polypropylene and high-density polyethylene are added, and the mixture is stirred to obtain a premix; S2. The compatibility agent, microcrystalline layered white mica and heat-resistant polyethylene are sequentially added to the premix, and after being stirred and mixed, the flame-retardant communication power sheath pipe material is obtained through melt extrusion, cooling and setting and traction cutting.

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