Polyethylene composite material for preparing cable sheath easy to tear in radial direction and optical cable

Abstract

The invention belongs to the technical field of cable sheath materials, and particularly relates to a polyethylene composite material for preparing a cable sheath easy to tear in the radial direction and an optical cable. The polyethylene composite material provided by the invention is obtained by mixing a polyethylene main body, an easy-to-tear inlay and a processing aid and then performing extrusion granulation, the easy-to-tear inlay comprises polyamide, polyester and a toughening agent, and the weight ratio of the easy-to-tear inlay to the polyethylene main body is (0.05-0.4): 1. The easy-to-tear inlay capable of forming a phase separation structure is introduced into the polyethylene main body, and the use amount of the easy-to-tear inlay is regulated, so that the cable sheath prepared from the polyethylene composite material is excellent in axial tensile property, easy to tear in the radial direction and good in dimensional stability; the cable can be torn linearly in the radial direction, deformation at the tearing position is small, tearing openings are neat, the internal structure of the cable can be effectively protected, meanwhile, convenient stripping performance can be provided in the construction and maintenance process, and the operation difficulty and cost are reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of cable sheath materials, and more specifically, relates to a polyethylene composite material and an optical cable for preparing a radially tearable cable sheath. Background Art

[0002] In the communications industry, optical cables are an important medium for information transmission, and the stability and reliability of their performance are crucial. As an important component of optical cables, the cable sheath not only needs to have excellent waterproof, high temperature resistance, and corrosion resistance to protect the internal structure of the optical cable from damage by the external environment, but also needs to be easy to tear in specific application scenarios to facilitate installation, construction, and maintenance.

[0003] The basic types of polyethylene (PE) materials include low-density polyethylene (LDPE) and high-density polyethylene (HDPE). HDPE material has the characteristics of high crystallinity, non-polarity and thermoplasticity. It is a high-quality thermoplastic material. The tubular structures such as water supply and drainage pipes, cables, and optical cable sheaths manufactured using this material have good economic benefits, stable interfaces, high mechanical strength, and good insulation. Therefore, it is widely used in construction, communications and other fields. With the rapid development of communication technology, the application scenarios of optical cables are becoming increasingly diversified, and the requirements for sheath materials are becoming higher and higher. In some emergency repair and rapid deployment scenarios, the importance of the easy-to-tear characteristics of sheath materials is becoming more and more prominent. However, the excellent mechanical properties of HDPE materials make the cable structures and tube structures manufactured using this material difficult to tear, large deformation at the tearing point, and poor dimensional stability. This leads to certain difficulties in the installation, construction, maintenance and disassembly of cable sheath products, limiting the application of HDPE materials in the preparation of cable products that require fast and convenient construction and maintenance.

[0004] Cable sheaths made of traditional polyethylene sheath materials are difficult to strip directly (radial tear strength greater than 300N), and require the design of cable ropes in the cable structure, or require the use of special tools for stripping. There are problems such as complex preparation steps, low efficiency, high cost, complex operation, and high difficulty in operation, which are not convenient for installation, processing, maintenance and disassembly. In order to meet the market demand for easy-to-tear PE cable sheaths, it is necessary to develop a polyethylene composite material suitable for preparing cable sheaths with good mechanical properties in axial tension, easy to tear in the radial direction and good dimensional stability, and can be torn in a radial straight line with neat tearing and small deformation. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a polyethylene composite material and an optical cable for preparing a radially tearable cable sheath, aiming to solve the problems of the existing cable sheath prepared with polyethylene composite materials, such as difficulty in radial stripping (radial tear strength greater than 300N), need for tools, complex and difficult operation, large deformation at the tear point, poor dimensional stability, and inability to tear along a radial straight line.

[0006] To achieve the above objectives, in a first aspect, the present application provides a polyethylene composite material for preparing a radial tearable cable sheath, which is obtained by mixing and kneading a polyethylene main body, an easy-tear inlay and a processing aid, and then extruding and granulating. The above-mentioned easy-tear inlay includes polyamide, polyester and a toughening agent, and the weight ratio of the easy-tear inlay to the polyethylene main body is (0.05~0.4):1.

[0007] Preferably, in the above-mentioned easy-to-tear inlay, the weight ratio of the above-mentioned polyamide to the polyester is 1:(0.5~2), and the added amount of the above-mentioned toughening agent is 1wt%~3wt% of the total weight of the above-mentioned polyamide and the above-mentioned polyester.

[0008] Preferably, the melting point of the polyamide is 170°C to 270°C.

[0009] Preferably, the polyamide is selected from one or more of nylon 6, nylon 66, nylon MXD-6, nylon 1010, nylon 11, nylon 12 and nylon 1212.

[0010] Preferably, the polyester is selected from one or more of polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate.

[0011] Preferably, the polyethylene main body has a number average molecular weight of 9,000 to 100,000 and is selected from one or more of high-density polyethylene, medium-density polyethylene and low-density polyethylene.

[0012] Further preferably, the above-mentioned polyethylene main body is composed of high-density polyethylene and low-density polyethylene, wherein the weight ratio of high-density polyethylene to low-density polyethylene is (1.5~5):1.

[0013] Preferably, the processing aids include one or more of a compatibilizer, an antioxidant, an anti-ultraviolet agent, a masterbatch, a heat stabilizer and an antistatic agent.

[0014] Preferably, the added amount of the above-mentioned processing aid is 1wt%~5wt% of the above-mentioned polyethylene main body.

[0015] Preferably, the compatibilizer is a maleic anhydride compatibilizer, selected from one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted POE and maleic anhydride grafted SEBS.

[0016] Preferably, the antioxidant is selected from one or more of antioxidant 1010 , antioxidant 1076 , antioxidant DLTDP and antioxidant 168 .

[0017] Preferably, the above-mentioned anti-ultraviolet agent is selected from one or more of benzoate anti-ultraviolet agents and amine anti-ultraviolet agents.

[0018] In a second aspect, the present application provides a method for preparing the above-mentioned polyethylene composite material, comprising the following steps: S1, blending the above-mentioned polyamide, polyester and toughening agent according to the ratio and granulating them, so that the polyester and the polyamide undergo an ester-amide exchange reaction to obtain an easy-to-tear inlay; S2, mixing the above-mentioned easy-to-tear inlay, the polyethylene main body and the processing aid according to the ratio, kneading and extruding granulation, so that the above-mentioned easy-to-tear inlay forms a dispersed phase separation structure in the polyethylene main body, and drying to obtain a polyethylene composite material.

[0019] Preferably, in step S1, the blending speed is 100-300 rpm, and the blending time is 5-10 min.

[0020] Preferably, in step S1, the granulation temperature is higher than the melting point of the polyamide, and the temperature difference is 10°C to 20°C.

[0021] Preferably, in step S2, the rotation speed of the mixing and kneading is 100-800 rpm, and the mixing and kneading time is 5-20 min.

[0022] Preferably, in step S2, the temperature of the extrusion granulation is within the range of ±5°C of the melting point of the polyamide.

[0023] In a third aspect, the present application provides a radially tearable cable sheath comprising the above-mentioned polyethylene composite material.

[0024] In a fourth aspect, the present application provides an optical cable, which includes the above-mentioned cable sheath.

[0025] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art: (1) The polyethylene composite material provided in the present application is obtained by mixing and kneading a polyethylene main body, an easy-tear inlay and a processing aid, and then extruding and granulating. The easy-tear inlay includes polyamide, polyester and a toughening agent, and the weight ratio of the easy-tear inlay to the polyethylene main body is (0.05~0.4):1. The present application introduces an easy-tear inlay that can form a phase separation structure into the polyethylene main body, and adjusts the ratio of the easy-tear inlay and the polyethylene main body, so that the cable sheath prepared by using the above polyethylene composite material has excellent axial tensile properties, radial easy tearing and good dimensional stability, can be torn in a radial straight line, has small deformation at the tearing point, and has a neat tear. The cable sheath prepared by using the polyethylene composite material provided in the present application can effectively protect the internal structure of the cable, and at the same time can provide convenient stripping performance during construction and maintenance, reducing the difficulty and cost of operation.

[0026] (2) This application can make the polyamide and polyester fully undergo ester-amide exchange reaction to produce block copolymers by regulating the ratio of polyamide, polyester and toughening agent in the tearable inlay, and at the same time adjust the number average molecular weight of the polyethylene main body so that the block copolymer is evenly dispersed in the polyethylene main body under the action of the processing aid compatibilizer to form a phase separation structure (i.e., tearable inlay). When using the above-mentioned polyethylene composite material to prepare a radially tearable cable sheath, the tearable inlay can maintain excellent tensile properties of the cable sheath along the processing direction (axial direction) during the extrusion process, with a tensile strength of 15~25MPa; the defects formed by the tearable inlay in the vertical axis method (radial direction) can reduce the difficulty of radial tearing, so that the cable sheath has the characteristic of radially easy tearing, and the radial tear strength is 50~200N. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a method for preparing a polyethylene composite material provided in an embodiment of the present application; Figure 2 This is a radial tearing picture of the cable sheath sample prepared in Example 1 of the present application; Figure 3 This is a radial tearing picture of the cable sheath sample prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] In the description of this application, it should be understood that the term "and / or" is a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " herein indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0030] In the specification and claims of the present application, the terms "first" and "second" etc. are used to distinguish different objects rather than to describe the specific order of the objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0031] In the description of the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0032] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0033] For the cable sheath, the term "axial" refers to the direction along the length of the cable sheath, and the term "radial" refers to the direction perpendicular to the axial direction of the cable sheath and from the center of the cable to the outside.

[0034] The radial tear strength of the cable sheath prepared by traditional polyethylene sheath material is usually greater than 300N, which is difficult to strip directly, and the radial tearing performance is poor. It is necessary to design a cable opening aid in the cable structure, or use a special tool for stripping. There are problems such as complex preparation steps, low efficiency, high cost, complex operation, high difficulty in operation, and it is not convenient to install, process, repair and disassemble. Based on this, the present application provides a polyethylene composite material for preparing a radial tearable cable sheath, which is obtained by mixing and kneading a polyethylene main body, an easy-tear inlay and a processing aid, and then extruding and granulating. The above-mentioned easy-tear inlay includes polyamide, polyester and a toughening agent, and the weight ratio of the above-mentioned easy-tear inlay to the above-mentioned polyethylene main body is (0.05~0.4):1.

[0035] In some embodiments, the polyethylene main body has a number average molecular weight of 9,000 to 100,000 and is selected from one or more of high-density polyethylene, medium-density polyethylene and low-density polyethylene.

[0036] In some embodiments, the polyethylene main body is composed of high-density polyethylene and low-density polyethylene, wherein the weight ratio of high-density polyethylene to low-density polyethylene is (1.5~5):1, which can control the number average molecular weight of the polyethylene main body within a suitable range, thereby regulating the mechanical strength of the cable sheath prepared using the polyethylene composite material.

[0037] In some embodiments, the number average molecular weight of the high-density polyethylene is 40,000-300,000, and the density is 0.940-0.964 g / cm 3 .

[0038] In some embodiments, the number average molecular weight of the low-density polyethylene is 5000-20000, and the density is 0.910-0.930 g / cm 3 .

[0039] In some embodiments, in the above-mentioned easy-to-tear inlay, the weight ratio of the above-mentioned polyamide and polyester is 1:(0.5~2), preferably 1:(0.5~1.5), so that the polyamide and polyester can fully undergo ester-amide exchange reaction during the processing.

[0040] In some embodiments, in the tearable inlay, the amount of the toughening agent added is 1 wt% to 3 wt% of the total weight of the polyamide and the polyester.

[0041] In some embodiments, the melting point of the polyamide is 170°C to 270°C.

[0042] In some embodiments, the polyamide is selected from one or more of nylon 6, nylon MXD-6, nylon 66, nylon 1010, nylon 11, nylon 12 and nylon 1212.

[0043] In some embodiments, the polyester is selected from one or more of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT).

[0044] In some embodiments, the toughening agent is a non-crosslinking toughening agent, including a non-crosslinking non-reactive toughening agent (also called a non-active toughening agent) and / or a non-crosslinking reactive toughening agent (also called an active toughening agent).

[0045] It is understood that the present application does not specifically limit the specific types of the above-mentioned toughening agents. In some embodiments, the above-mentioned non-crosslinked non-reactive toughening agents include but are not limited to EMA (ethylene-methyl acrylate copolymer), EBA (ethylene-butyl acrylate copolymer), EPDM (ethylene propylene diene monomer rubber), and thermoplastic styrene elastomers. In some embodiments, the above-mentioned non-crosslinked reactive toughening agents include but are not limited to EMA-g-MAH (ethylene-methyl acrylate grafted maleic anhydride copolymer), EMA-g-GMA (ethylene-methyl acrylate grafted methacrylate glycidyl copolymer), EBA-g-MAH (ethylene-butyl acrylate grafted maleic anhydride copolymer), EBA-g-GMA (ethylene-butyl acrylate grafted methacrylate glycidyl copolymer), and thermoplastic styrene elastomer grafted active functional groups.

[0046] In the present application, the molecular chain of the polyamide mentioned above contains a large number of polar amide bonds, and the polar groups on the molecular chain can interact with each other through hydrogen bonds, so that the polyamide is highly oriented along the main chain and has anisotropic properties. During the processing, the polyamide and polyester undergo an ester-amide exchange reaction to produce a block copolymer. At the same time, under the action of a processing aid compatibilizer, the block copolymer is evenly dispersed in the polyethylene substrate to form a phase separation structure (i.e., an easy-to-tear inlay), so that the cable sheath prepared by the polyethylene composite material can maintain excellent tensile properties in the axial direction (tensile strength is 15~25MPa). When radial tearing is performed, the defects formed by the phase separation structure can reduce the difficulty of radial tearing and facilitate radial tearing (radial tearing strength is 50~200N). At the same time, it can reduce the elongation of the cable sheath when it is torn, ensure the dimensional stability of the product, and enable it to be torn in a radial straight line, with small deformation at the tearing site and neat tearing. The cable sheath prepared using the polyethylene composite material provided in this application has high axial tensile strength and can effectively protect the internal structure of the cable. At the same time, its radially tearable property can provide convenient stripping performance during construction and subsequent maintenance, reducing operational difficulty and cost. That is, the polyethylene composite material provided in the application is suitable for preparing radially tearable cable sheaths.

[0047] In some embodiments, the added amount of the above-mentioned processing aid is 1wt%~5wt% of the above-mentioned polyethylene main body.

[0048] In order to meet the requirements of different application environments and facilitate material processing, the polyethylene composite material prepared in this application also includes processing aids to give the above-mentioned polyethylene composite material various properties or reduce the difficulty of processing and improve production efficiency. The above-mentioned processing aids include but are not limited to one or more of compatibilizers, antioxidants, anti-ultraviolet agents, masterbatches, thermal stabilizers and antistatic agents. Specifically, the compatibilizer can improve the mixing uniformity of the raw materials so that the above-mentioned easy-to-tear inlays are evenly dispersed in the polyethylene body; the antioxidant can improve the antioxidant properties of the polyethylene composite material during the processing and use process and increase the service life; the masterbatch can meet the needs of different customers or different application scenarios for the color of the cable sheath product; the antistatic agent can increase the antistatic property of the polyethylene composite material, etc.

[0049] It is understood that the present application does not specifically limit the type of the above-mentioned compatibilizer, and the compatibilizers for polyethylene materials disclosed in the prior art are all applicable to the present application. In some embodiments, the above-mentioned compatibilizer is a maleic anhydride compatibilizer, such as but not limited to one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted POE and maleic anhydride grafted SEBS.

[0050] In some embodiments, the antioxidant may be selected from, but not limited to, one or more of antioxidant 1010 , antioxidant 1076 , antioxidant DLTDP, and antioxidant 168 .

[0051] In some embodiments, the anti-ultraviolet agent is selected from one or more of benzoate anti-ultraviolet agents and amine anti-ultraviolet agents. Specifically, the benzoate anti-ultraviolet agent can be, but is not limited to, one or more of anti-ultraviolet agent RMB, anti-ultraviolet agent UV-120, and anti-ultraviolet agent UV-2908. The amine anti-ultraviolet agent can be, but is not limited to, a hindered amine light stabilizer.

[0052] On the other hand, the present application also provides a method for preparing the above polyethylene composite material, such as Figure 1 As shown, the following steps are included: S1, blending the polyamide, polyester and toughening agent according to the ratio and granulating them, so that the polyester and the polyamide undergo ester-amide exchange reaction to obtain an easy-to-tear inlay; S2, mixing the above-mentioned easy-to-tear inlay, the polyethylene main body and the processing aid according to the ratio, kneading and extruding granulation, so that the above-mentioned easy-to-tear inlay forms a dispersed phase separation structure in the polyethylene main body, and drying to obtain a polyethylene composite material.

[0053] The present application does not limit the method of "blending" in step S1, as long as the components can be mixed evenly, it is within the protection scope of the present application. In some embodiments, the above blending can be but is not limited to stirring and mixing.

[0054] In some embodiments, the blending speed is 100-300 rpm, and the blending time is 5-10 min. Those skilled in the art can adaptably increase / decrease the blending speed, extend or shorten the blending time according to different blending methods, which are all within the scope of protection of this application.

[0055] In some embodiments, when preparing the tearable inlay in step S1, the granulation temperature is higher than the melting point of the polyamide, and the temperature difference is 10°C to 20°C, which can cause the polyester and the polyamide to undergo an ester-amide exchange reaction. In some embodiments, in step S1, the granulation temperature can be 180°C to 280°C.

[0056] In some embodiments, in step S1, the specific operation of the granulation is: discharging the blended material mass into a twin-screw extruder granulator, and obtaining an easily tearable inlay through the processes of extrusion, strip drawing, pelletizing, and drying.

[0057] In the specific embodiment of the present application, when the polyamide is nylon 66, in the process of preparing the tearable inlay, the process conditions of granulation are: screw speed: 300~500rpm, the temperature of each section is: zone 1 190℃~210℃, zone 2 210℃~230℃, zone 3 230℃~250℃, zone 4 250℃~270℃, zone 5 250℃~270℃, zone 6 230℃~250℃, and the head temperature is 200℃~220℃. It can be understood that according to the specific type and amount of the selected polyamide material and the difference of the laboratory extrusion granulator, the screw speed can be adjusted (increased / decreased) and the temperature of each section can be increased / decreased, which are all within the protection scope of the present application.

[0058] In some embodiments, in step S2, the speed of mixing and kneading is 100-800 rpm, and the time of mixing and kneading is 5-20 min. In practical application, those skilled in the art can adaptably increase or decrease the speed of mixing and kneading, extend or shorten the time of mixing and kneading according to the mixing and kneading method, which is within the protection scope of this application.

[0059] In some embodiments, when preparing the polyethylene composite material in step S2, the temperature of the extrusion granulation is controlled within the range of ±5°C of the melting point of the polyamide, so that the tearable inlay is partially melted and can be dispersed in the polyethylene main body under the action of the compatibilizer, and a uniformly dispersed phase separation structure can be formed. In a specific embodiment of the present application, the temperature of the extrusion granulation can be 150°C to 260°C.

[0060] In a specific embodiment of the present application, when the polyamide is nylon 66, in the process of preparing the polyethylene composite material, the process conditions of extrusion granulation are: screw speed: 300~500rpm, the temperature of each section is: zone 1 180℃~200℃, zone 2 180℃~200℃, zone 3 200℃~220℃, zone 4 220℃~240℃, zone 5 240℃~260℃, zone 6 240℃~260℃, and the head temperature is 180℃~200℃. It can be understood that according to the specific type and amount of polyamide selected in the above step S1, and the difference of the laboratory extrusion granulator, the adaptive adjustment (increase / decrease) of the screw speed and the adaptive increase / decrease of the temperature of each section are all within the protection scope of the present application.

[0061] On the other hand, the present application also provides an application of the polyethylene composite material in preparing a radially tearable cable sheath. The polyethylene composite material provided in the present application is suitable for preparing a radially tearable cable sheath. The present application does not limit the preparation method of the cable sheath. For example, the polyethylene composite material is placed in an extrusion device, mixed and melted, and then formed into a ring structure that wraps the cable through a mold, and then cooled and solidified to obtain a cable sheath.

[0062] Based on this, the present application also provides a radially tearable cable sheath, which includes the above-mentioned polyethylene composite material.

[0063] In some embodiments, the cable sheath includes but is not limited to an optical cable sheath and an electrical cable sheath.

[0064] On the other hand, the present application also provides an optical cable, which includes the above-mentioned cable sheath.

[0065] It should be understood that materials of the same or similar type, model, quality, nature or function as the reagents and instruments used in the following examples can be used to implement the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0066] The following are examples and comparative examples: Example 1 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 12.3 parts of tearable inlay (6 parts of polyamide nylon 66, 6 parts of polybutylene terephthalate PBT, 0.3 parts of toughening agent Lotader AX8900), 150 parts of polyethylene body (90 parts of high-density polyethylene HDPE, number average molecular weight of 98,000, density of 0.951 g / cm³; 60 parts of low-density polyethylene LDPE, number average molecular weight of 11,000, density of 0.917 g / cm³), 6 parts of processing aids (2 parts of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0067] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 66, PBT and Lotader AX8900 are mixed, stirred at a speed of 200 rpm for 8 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 300 rpm, wherein the temperature of each section of the machine barrel is: 210°C in zone 1, 230°C in zone 2, 240°C in zone 3, 260°C in zone 4, 270°C in zone 5, 250°C in zone 6, and the head temperature is 220°C to obtain an easy-to-tear inlay.

[0068] S2. According to the above ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted polyethylene, antioxidant 1010, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 500 rpm for 10 minutes to obtain a second mixed material, and then the second mixed material is extruded and granulated, with a screw speed of 500 rpm, wherein the temperatures of various sections of the barrel are: 180°C for zone 1, 200°C for zone 2, 220°C for zone 3, 230°C for zone 4, 250°C for zone 5, and 260°C for zone 6, and the head temperature is 190°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0069] Example 2 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 22.5 parts of tearable inlay (12 parts of polyamide nylon 66, 10 parts of polybutylene terephthalate PBT, 0.5 parts of toughening agent Lotader AX8900), 150 parts of polyethylene main body (112.5 parts of high-density polyethylene HDPE, number average molecular weight of 60,000, density of 0.942g / cm³; 37.5 parts of low-density polyethylene LDPE, number average molecular weight of 9,000, density of 0.915g / cm³), 6 parts of processing aids (1 part of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908, 1 part of masterbatch).

[0070] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 66, PBT and Lotader AX8900 are mixed, stirred at a speed of 100 rpm for 10 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 400 rpm, wherein the temperature of each section of the machine barrel is: 210°C in zone 1, 220°C in zone 2, 230°C in zone 3, 250°C in zone 4, 260°C in zone 5, 260°C in zone 6, and the head temperature is 210°C to obtain an easy-to-tear inlay.

[0071] S2. According to the above ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted polyethylene, antioxidant 1010, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 800 rpm for 5 minutes to obtain a second mixed material, and then the second mixed material is extruded into granules, and the screw speed is 400 rpm, wherein the temperatures of each section of the machine barrel are: 180°C for zone 1, 190°C for zone 2, 210°C for zone 3, 230°C for zone 4, 250°C for zone 5, and 260°C for zone 6, and the head temperature is 200°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0072] Example 3 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 53.5 parts of tearable inlay (32 parts of polyamide nylon 66, 20 parts of polybutylene terephthalate PBT, 1.5 parts of toughening agent Lotader AX8900), 150 parts of polyethylene body (120 parts of high-density polyethylene HDPE, number average molecular weight of 50,000, density of 0.940 g / cm³; 30 parts of low-density polyethylene LDPE, number average molecular weight of 5,000, density of 0.912 g / cm³), 6 parts of processing aids (2 parts of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0073] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 66, PBT and Lotader AX8900 are mixed, stirred at a speed of 300 rpm for 5 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 500 rpm, wherein the temperature of each section of the machine barrel is: 190°C in zone 1, 210°C in zone 2, 230°C in zone 3, 250°C in zone 4, 270°C in zone 5, 250°C in zone 6, and the head temperature is 210°C to obtain an easy-to-tear inlay.

[0074] S2. According to the above ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted polyethylene, antioxidant 1010, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 100 rpm for 20 minutes to obtain a second mixed material, and then the second mixed material is extruded into granules, and the screw speed is 300 rpm, wherein the temperatures of each section of the machine barrel are: 200°C for zone 1, 200°C for zone 2, 220°C for zone 3, 240°C for zone 4, 260°C for zone 5, and 260°C for zone 6, and the head temperature is 200°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0075] Example 4 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 30.5 parts of tearable inlay (15 parts of polyamide nylon 66, 15 parts of polybutylene terephthalate PBT, 0.5 parts of toughening agent Lotader AX8900), 110 parts of polyethylene main body (90 parts of high-density polyethylene HDPE, the same as in Example 1; 20 parts of low-density polyethylene LDPE, the same as in Example 1), 4 parts of processing aids (1 part of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120).

[0076] Example 5 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 60 parts of tearable inlay (28 parts of polyamide nylon 66, 31.5 parts of polybutylene terephthalate PBT, 1.5 parts of toughening agent Lotader AX8900), 150 parts of polyethylene main body (125 parts of high-density polyethylene HDPE, the same as in Example 1; 25 parts of low-density polyethylene LDPE, the same as in Example 1), 6 parts of processing aids (2 parts of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0077] Example 6 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 18 parts of tearable inlay (7 parts of polyamide nylon 66, 10.5 parts of polybutylene terephthalate PBT, 0.5 parts of toughening agent Lotader AX8900), 180 parts of polyethylene main body (120 parts of high-density polyethylene HDPE, the same as in Example 1; 60 parts of low-density polyethylene LDPE, the same as in Example 1), 7 parts of processing aids (3 parts of maleic anhydride grafted polyethylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of masterbatch).

[0078] Example 7 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 12.3 parts of tearable inlay (6 parts of polyamide nylon MXD-6, 6 parts of polybutylene terephthalate PET, 0.3 parts of toughening agent Lotader AX8900), 130 parts of polyethylene main body (90 parts of high-density polyethylene HDPE, the same as in Example 1; 40 parts of low-density polyethylene LDPE, the same as in Example 1), 5 parts of processing aids (1 part of maleic anhydride grafted POE, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0079] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon MXD-6, PET and toluenesulfonic acid are mixed, stirred at a speed of 300 rpm for 5 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 500 rpm, wherein the temperature of each section of the machine barrel is: 180°C in zone 1, 190°C in zone 2, 220°C in zone 3, 240°C in zone 4, 250°C in zone 5, 230°C in zone 6, and the head temperature is 200°C to obtain an easy-to-tear inlay.

[0080] S2. According to the above ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted POE, antioxidant 1010, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 100 rpm for 20 minutes to obtain a second mixed material, and then the second mixed material is extruded into granules, and the screw speed is 300 rpm, wherein the temperatures of each section of the machine barrel are: 180°C for zone 1, 200°C for zone 2, 220°C for zone 3, 220°C for zone 4, 240°C for zone 5, and 240°C for zone 6, and the head temperature is 180°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0081] Example 8 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 15.5 parts of tearable inlay (8.5 parts of polyamide nylon 1010, 6.7 parts of polybutylene terephthalate PTT, 0.3 parts of toughening agent Lotader AX8900), 150 parts of polyethylene main body (90 parts of high-density polyethylene HDPE, the same as in Example 1; 60 parts of low-density polyethylene LDPE, the same as in Example 1), 6 parts of processing aids (2 parts of maleic anhydride grafted polypropylene, 1 part of antioxidant 1076, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0082] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 1010, PTT and Lotader AX8900 are mixed, stirred at a speed of 300 rpm for 5 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 500 rpm, wherein the temperature of each section of the machine barrel is: 180°C in zone 1, 180°C in zone 2, 190°C in zone 3, 200°C in zone 4, 210°C in zone 5, 200°C in zone 6, and the head temperature is 180°C to obtain an easy-to-tear inlay.

[0083] S2. According to the above-mentioned ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted polypropylene, antioxidant 1076, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 100 rpm for 20 minutes to obtain a second mixed material, and then the second mixed material is extruded into granules, and the screw speed is 300 rpm, wherein the temperatures of each section of the machine barrel are: 170°C for zone 1, 180°C for zone 2, 180°C for zone 3, 200°C for zone 4, 210°C for zone 5, and 190°C for zone 6, and the head temperature is 170°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0084] Example 9 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 27.8 parts of tearable inlay (12 parts of polyamide nylon 11, 15 parts of polybutylene terephthalate PBT, 0.8 parts of toughening agent Lotader AX8900), 160 parts of polyethylene main body (110 parts of high-density polyethylene HDPE, the same as in Example 2; 50 parts of low-density polyethylene LDPE, the same as in Example 2), 6 parts of processing aids (2 parts of maleic anhydride grafted SEBS, 1 part of antioxidant 1010, 1 part of antioxidant DLTDP, 1 part of UV-120, 1 part of UV-2908).

[0085] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 11, PBT and Lotader AX8900 are mixed, stirred at a speed of 300 rpm for 5 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 500 rpm, wherein the temperatures of each section of the machine barrel are: 170°C in zone 1, 180°C in zone 2, 180°C in zone 3, 190°C in zone 4, 200°C in zone 5, 190°C in zone 6, and the head temperature is 170°C to obtain an easy-to-tear inlay.

[0086] S2. According to the above-mentioned ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted SEBS, antioxidant 1010, antioxidant DLTDP, UV-120, and UV-2908, and stirred at a speed of 100 rpm for 20 minutes to obtain a second mixed material, and then the second mixed material is extruded and granulated, with a screw speed of 300 rpm, wherein the temperatures of each section of the barrel are: 170°C for zone 1, 170°C for zone 2, 180°C for zone 3, 180°C for zone 4, 190°C for zone 5, and 190°C for zone 6, and the head temperature is 160°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0087] Example 10 The polyethylene composite material provided in this embodiment includes the following components and their weight proportions: 25.5 parts of tearable inlay (13 parts of polyamide nylon 1212, 12 parts of polybutylene terephthalate PBT, 0.5 parts of toughening agent Lotader AX8900), 120 parts of polyethylene main body (90 parts of high-density polyethylene HDPE, the same as in Example 3; 30 parts of low-density polyethylene LDPE, the same as in Example 3), 5 parts of processing aids (1 part of maleic anhydride grafted polypropylene, 1 part of antioxidant 1010, 1 part of antioxidant 168, 1 part of UV-120, 1 part of UV-2908).

[0088] The method for preparing the polyethylene composite material comprises the following steps: S1. According to the above ratio, the above nylon 1212, PBT and Lotader AX8900 are mixed, stirred at a speed of 300 rpm for 5 minutes to obtain a first mixed material, and then the first mixed material is vacuum sucked into the extruder hopper for extrusion granulation, the screw speed is 400 rpm, wherein the temperature of each section of the machine barrel is: 170°C in zone 1, 180°C in zone 2, 180°C in zone 3, 190°C in zone 4, 200°C in zone 5, 170°C in zone 6, and the head temperature is 160°C to obtain an easy-to-tear inlay.

[0089] S2. According to the above ratio, the above-mentioned easy-tear inlay is mixed with HDPE, LDPE, maleic anhydride grafted POE, antioxidant 1010, antioxidant 168, UV-120, and UV-2908, and stirred at a speed of 100 rpm for 20 minutes to obtain a second mixed material, and then the second mixed material is extruded into granules, and the screw speed is 300 rpm, wherein the temperatures of each section of the machine barrel are: 160°C for zone 1, 160°C for zone 2, 170°C for zone 3, 170°C for zone 4, 180°C for zone 5, and 180°C for zone 6, and the head temperature is 150°C. The polyethylene composite material is obtained by water-cooled strand cutting and then drying.

[0090] Comparative Example 1 The polyethylene composite material provided in this comparative example does not contain an easily tearable inlay, and the rest is the same as in Example 1.

[0091] The preparation method of the polyethylene composite material provided in this comparative example is the same as that in Example 1.

[0092] Comparative Example 2 The polyethylene composite material provided in this comparative example includes 6 parts of easy-tear inlays (2.9 parts of polyamide nylon 66, 2.9 parts of polybutylene terephthalate PBT, and 0.2 parts of toughening agent Lotader AX890), and the rest is the same as in Example 1.

[0093] The preparation method of the polyethylene composite material provided in this comparative example is the same as that in Example 1.

[0094] Comparative Example 3 The polyethylene composite material provided in this comparative example includes 70 parts of easy-tear inlays (34 parts of nylon 66, 34 parts of polybutylene terephthalate PBT, and 2 parts of toughening agent Lotader AX8900), and the rest is the same as in Example 1.

[0095] The preparation method of the polyethylene composite material provided in this comparative example is the same as that in Example 1.

[0096] Comparative Example 4 The polyethylene composite material provided in this comparative example includes 150 parts of polyethylene main body (130 parts of high-density polyethylene and 20 parts of low-density polyethylene), and the rest is the same as in Example 1.

[0097] The preparation method of the polyethylene composite material provided in this comparative example is the same as that in Example 1.

[0098] Comparative Example 5 The polyethylene composite material provided in this comparative example includes 150 parts of polyethylene main body (75 parts of high-density polyethylene and 75 parts of low-density polyethylene, and the rest is the same as in Example 1.

[0099] The preparation method of the polyethylene composite material provided in this comparative example is the same as that in Example 1.

[0100] The polyethylene composite materials prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were mixed and melted, and then formed into a ring structure for wrapping the cable through a semi-extrusion die, and then cooled and solidified to obtain a cable sheath sample. The performance test of the cable sheath sample was carried out, and the test method was as follows: 1) Radial tearing performance The trouser-type tearing method was used to test the radial tearing performance of the sample. Specifically, a sample with a length of 15 cm, a width of 5 cm, and a thickness of 2 mm was cut in the radial direction. The sample was cut to half of the length in the radial direction to form two parts similar to trouser legs. The samples were then clamped on the upper and lower clamps of the tensile testing machine respectively. The centers of the connecting lines of the main axis of the sample and the clamps coincided to ensure that the sample was evenly stressed during the test. The test speed was set to 100 mm / min, and a tensile force was applied to the sample to expand the crack in the radial direction. The radial maximum tearing force was used to represent the radial tearing strength of the sample. The radial tearing curve of the sample and the fracture morphology of the sample after tearing were observed to comprehensively evaluate the radial tearing performance of the sample.

[0101] Figure 2 , Figure 3 The radial tearing effect diagrams of the cable sheath samples prepared by using the polyethylene composite materials provided by Example 1 and Comparative Example 1 are respectively.

[0102] 2) Axial tensile properties Refer to GB / T 1040 to test the axial tensile strength of the specimen.

[0103] The test results are shown in Table 1.

[0104] Table 1 Properties of cable sheath samples prepared in Examples 1 to 10 and Comparative Examples 1 to 5

[0105] The test results show that the cable sheath prepared by the present application has excellent axial tensile properties (tensile strength of 15-25MPa), good radial tearing properties (i.e. radial tearing strength of 50-200N), high dimensional stability, and can be torn in a radial straight line with small deformation at the tearing point and neat tearing. In practical applications, the cable sheath prepared by the polyethylene composite material provided by the present application can effectively protect the internal structure of the cable, and at the same time can provide convenient stripping performance, reduce the difficulty and cost of operation, and facilitate the installation, construction, and maintenance of the cable sheath.

[0106] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A polyethylene composite material for preparing a radially tearable cable sheath, characterized in that: It is obtained by mixing and kneading the polyethylene main body, the easy-tear inlay and the processing aid, and then extruding and granulating. The tearable inlay comprises polyamide, polyester and a toughening agent, and the weight ratio of the tearable inlay to the polyethylene main body is (0.05-0.4):

1.

2. The polyethylene composite material according to claim 1, characterized in that: The number average molecular weight of the polyethylene main body is 9000-100000, and is selected from one or more of high-density polyethylene, medium-density polyethylene and low-density polyethylene.

3. The polyethylene composite material according to claim 1, characterized in that: In the tearable inlay, the weight ratio of the polyamide to the polyester is 1:(0.5-2), and the added amount of the toughening agent is 1wt%-3wt% of the total weight of the polyamide and the polyester.

4. The polyethylene composite material according to claim 3, characterized in that: The melting point of the polyamide is 170° C. to 270° C.; optionally, the polyamide is selected from one or more of nylon 6, nylon 66, nylon MXD-6, nylon 1010, nylon 11, nylon 12 and nylon 1212; and / or, The polyester is selected from one or more of polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate; and / or, The toughening agent is a non-crosslinking toughening agent, including a non-crosslinking non-reactive toughening agent and / or a non-crosslinking reactive toughening agent.

5. The polyethylene composite material according to claim 1, characterized in that: The polyethylene main body is composed of high-density polyethylene and low-density polyethylene, wherein the weight ratio of the high-density polyethylene to the low-density polyethylene is (1.5~5):

1.

6. The polyethylene composite material according to claim 1, characterized in that: The processing aids include one or more of a compatibilizer, an antioxidant, an anti-ultraviolet agent, a masterbatch, a heat stabilizer and an antistatic agent; and / or, The added amount of the processing aid is 1wt%~5wt% of the polyethylene main body.

7. The method for preparing the polyethylene composite material according to any one of claims 1 to 6, comprising the following steps: S1, blending the polyamide, polyester and toughening agent according to a ratio and granulating the mixture, so that the polyester and the polyamide undergo an ester-amide exchange reaction to obtain an easily tearable inlay; S2, mixing the tearable inlay, the polyethylene main body and the processing aid according to the ratio, kneading and extruding and granulating, so that the tearable inlay forms a dispersed phase separation structure in the polyethylene main body, and drying to obtain a polyethylene composite material.

8. The preparation method according to claim 7, characterized in that: In step S1, the blending speed is 100-300 rpm, the blending time is 5-10 min, the granulation temperature is higher than the melting point of the polyamide, and the temperature difference is 10° C.-20° C.; and / or, In step S2, the rotation speed of the mixing and kneading is 100-800 rpm, the mixing and kneading time is 5-20 min, and the temperature of the extrusion granulation is within the range of ±5°C of the melting point of the polyamide.

9. A radially tearable cable sheath, characterized in that: It comprises the polyethylene composite material according to any one of claims 1 to 6.

10. An optical cable, characterized in that: It comprises the cable sheath as claimed in claim 9.

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