Polypropylene composite material for wires and cables as well as preparation method and application of polypropylene composite material

Abstract

The invention relates to a polypropylene composite material for wires and cables as well as a preparation method and application of the polypropylene composite material. The polypropylene composite material mainly comprises polypropylene, an ethylene-vinyl acetate copolymer (EVA), a compatilizer, glass fibers, an ethylene-octylene copolymer and the like. Wherein the ethylene-vinyl alcohol copolymer (EVOH) and the low-melting-point glass powder are prepared into the functional master batch through a specific process, and all the components are matched according to specific parts by weight, so that the comprehensive performance of the material is ensured. The obtained polypropylene-based composite material not only has excellent thermal aging resistance, but also shows excellent tensile strength and good elongation at break, and especially has excellent impact performance under a low-temperature condition. Besides, the polypropylene material has extremely low permeation coefficients for oxygen and water vapor, moisture and oxygen are effectively isolated, the internal structure is protected from being influenced by the external environment, and the stability of the polypropylene material can be kept in the extreme environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable materials, and particularly relates to a polypropylene composite material for wire and cable, a preparation method thereof, and an application thereof in cables. Background Art

[0002] When cable materials are subjected to moisture penetration, high-temperature oxidation, or long-term exposure to low-temperature environments, their mechanical toughness, electrical properties, and heat resistance often rapidly deteriorate. If the cable is in an environment with alternating dry and wet conditions, or is immersed in water, high temperature, or steam for a long time, the rate of this performance degradation will be even faster. Such environmental conditions will exacerbate the aging of cable materials, resulting in weakened barrier properties and mechanical strength, thus affecting the reliability and safety of the cable. In the long run, these factors not only hinder the normal operation of the cable, but also greatly reduce the expected service life of the cable, increasing maintenance costs and replacement frequencies. Therefore, improving the stability and durability of cables in harsh environments is the key to ensuring the reliability of the power transmission system.

[0003] Polyolefin composites are gradually being applied in the wire and cable industry. Polyolefin materials such as polyethylene (PE) and polypropylene (PP) are favored for their excellent impact resistance, corrosion resistance, moisture barrier properties, and low cost. However, they have poor barrier properties to oxygen, water vapor, and hydrocarbon solvents, which may lead to solvent leakage and environmental pollution. In contrast, high-barrier resins, such as ethylene-vinyl alcohol copolymer (EVOH) and polyamide (PA), as polar polymer materials, exhibit excellent barrier properties and can effectively prevent the penetration of oxygen, carbon dioxide, and various hydrocarbon organic solvents. However, these high-barrier resins have strong hygroscopicity. Once they absorb moisture, their barrier properties and mechanical properties will be significantly reduced, and the cost is relatively high. In order to combine the advantages of both, high-barrier resins such as EVOH and PA are usually used as the dispersed phase and mixed with polyolefin matrices with poor barrier properties (such as PE and PP). Through appropriate processing and molding processes, the two are fully combined to prepare a composite material that not only has high barrier properties and impact resistance but also maintains good mechanical properties. This method can effectively improve the comprehensive performance of the material and meet the requirements of more application scenarios.

[0004] In view of the deficiencies of existing cable materials in terms of heat aging resistance, barrier properties, and low-temperature toughness, the present invention proposes a polypropylene composite material, which is specifically used for cable products. By combining ethylene-vinyl alcohol copolymer (EVOH) and low-melting-point glass powder, this composite material not only improves the heat resistance and barrier properties of the material, but also enhances its low-temperature toughness. As a high-barrier material, EVOH can effectively prevent the penetration of gases such as oxygen and carbon dioxide, and also has excellent barrier properties against a variety of hydrocarbon organic solvents. However, EVOH has strong hygroscopicity, and its performance will decline after moisture absorption. The combination of low-melting-point glass powder and EVOH into a functional masterbatch effectively improves this problem. Through this combination, the polypropylene composite material of the present invention maintains the cost-effectiveness of polyolefin materials while significantly improving its application performance in harsh environments, especially in terms of high-temperature aging resistance and barrier properties, effectively making up for the deficiencies of traditional polyolefin materials. Summary of the Invention

[0005] The purpose of the present invention is to provide an environmentally friendly polypropylene composite material for wire and cable with excellent heat oxidation resistance, low-temperature toughness, and at the same time excellent mechanical properties and barrier properties, as well as a preparation method thereof, to overcome the defects of the above-mentioned existing technologies.

[0006] The present invention provides a polypropylene composite material for wire and cable, comprising the following raw materials in parts by weight: 55-85 parts of polypropylene, 5-15 parts of ethylene-octene copolymer, 20-30 parts of ethylene-vinyl acetate copolymer, 10-20 parts of functional masterbatch, 10-20 parts of compatibilizer, 20-40 parts of glass fiber, 0.1-3 parts of antioxidant, 0.5-5 parts of color masterbatch, and 1-5 parts of lubricant.

[0007] The functional masterbatch is prepared by the following method:

[0008] S1. Mix low-melting-point glass powder and coupling agent evenly according to a mass ratio of 1:0.5-1 to obtain modified low-melting-point glass powder;

[0009] S2. Take 30-40 parts of the modified low-melting-point glass powder obtained in step S1, 30-50 parts of ethylene-vinyl alcohol copolymer, 20-30 parts of maleic anhydride grafted polypropylene, and 2-8 parts of processing aid, mix them evenly in a high-speed mixer, and add them to a twin-screw extruder for extrusion granulation to obtain the functional masterbatch.

[0010] The melt flow rate of the ethylene-vinyl alcohol copolymer is 2-20 g / 10 min at 210 °C and 2.16 kg, and the ethylene content is 24-48 mol%.

[0011] The coupling agent in the step S1 includes one or more of vinyl silane coupling agent, amino silane coupling agent, methacryloxy silane coupling agent, titanate coupling agent, and aluminum-titanium composite silane coupling agent.

[0012] The processing aid in the step S2 is at least one of antioxidant and lubricant.

[0013] The polypropylene is homopolypropylene or propylene-ethylene copolymer, and the melt index of the polypropylene resin under the test conditions of 230 °C and 2.16 KG is 10-100 g / 10 min.

[0014] The compatibilizer is at least one of maleic anhydride grafted polypropylene and maleic anhydride grafted polyethylene.

[0015] The glass fiber is chopped glass fiber with a length of 5-10 mm.

[0016] The melting point of the low-melting glass powder is 400 °C - 900 °C, and preferably the melting point of the low-melting glass powder is 500 °C - 700 °C.

[0017] The melt index of the ethylene-vinyl acetate copolymer at 190 °C and 2.16 kg is 1-3 g / 10 min, and the vinyl acetate content is 14-18 wt%.

[0018] The antioxidant includes at least one of hindered phenol antioxidants and phosphite antioxidants.

[0019] The lubricant includes one or more of erucamide, oleamide, EBS amide, PE wax, and stearate.

[0020] The present invention cleverly utilizes the excellent barrier properties of ethylene-vinyl alcohol copolymer (EVOH) to effectively reduce the permeation of oxygen and water vapor. The thermal stability and abundant hydroxyl groups of EVOH enable it to be uniformly blended with polypropylene, thus significantly improving the heat aging resistance of the polypropylene composite material. Although the EVOH resin has strong hygroscopicity, which will lead to a decrease in its barrier properties and mechanical properties, by combining the low-melting glass powder with EVOH and using twin-screw extrusion technology to make masterbatch, an inorganic layer with high chemical stability and high mechanical strength can be formed, effectively reducing the hygroscopicity of EVOH and further enhancing the barrier properties of the composite material. By applying a coupling agent on the surface of the low-melting glass powder particles for modification treatment, the adhesion between EVOH and the glass powder can be significantly enhanced, and the compatibility between the glass powder, EVOH, and EVA can be improved. This modification not only optimizes the interaction between materials but also further enhances the comprehensive properties such as the low-temperature toughness and heat aging resistance of the polypropylene material.

[0021] By introducing EVA into the polypropylene composite material, the present invention makes full use of the flexibility and elasticity provided by EVA, thereby significantly improving the toughness of the composite material, especially its toughness performance under low-temperature conditions. At the same time, EVA shows good compatibility with both polypropylene and EVOH. Its addition not only enhances the interfacial adhesion between PP and EVOH but also promotes the compatibility among various components, thus significantly enhancing the barrier performance, heat aging resistance, and low-temperature toughness of polypropylene.

[0022] The present invention also provides a method for preparing a polypropylene composition for wire and cable, comprising:

[0023] (1) Weigh various raw materials according to the ratio;

[0024] (2) Add the above raw materials into a mixer and mix evenly to obtain a mixed material; the temperature of the mixer is 50 - 70°C, and the rotation speed of the mixer is 100 - 150 r / min;

[0025] (3) Add the mixed material obtained in step (2) into a twin-screw extruder for extrusion granulation to obtain the polypropylene composite material.

[0026] The temperatures of the twin-screw extruder from the feeding section to the head are successively: 150 - 160°C, 170 - 180°C, 190 - 200°C, 190 - 200°C, 190 - 210°C, 190 - 220°C, 190 - 220°C, the screw rotation speed is 300 - 450 r / min, and the screw length-diameter ratio is 48:1.

[0027] The present invention also relates to a power cable, comprising a conductor, a modified barrier layer, and an outer sheath arranged in sequence from inside to outside; the modified barrier layer is a modified polypropylene barrier layer, and the modified polypropylene barrier layer is prepared from the polypropylene composite material of the present invention.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1) The present invention makes a masterbatch from ethylene-vinyl alcohol copolymer and low-melting glass powder, enabling the polypropylene composition to have both high heat-oxidative aging resistance and barrier performance.

[0030] 2) The present invention utilizes the excellent flexibility and elasticity of EVA to enhance the interfacial adhesion between PP and EVOH, promote the compatibility among various components, and thus significantly enhance the barrier performance of polypropylene, especially its low-temperature toughness.

[0031] 3) The polypropylene composite prepared by the present invention not only has excellent thermal aging resistance, but also has excellent tensile strength and good elongation at break. In particular, it has very good low-temperature impact performance, and the gas permeability coefficients for oxygen and water vapor are extremely low, which can effectively isolate moisture and oxygen, protecting the internal structure from the influence of the external environment. This enables it to maintain stability in extreme environments and is an ideal material choice for manufacturing cables. Detailed Embodiments

[0032] The technical solution of the present invention will be further described below in conjunction with the detailed embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the claimed protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0033] Experimental Materials:

[0034] Polypropylene Resin 1#: Homopolypropylene, HJ4045, from Hanwha Total Petrochemical, melt index 45 g / 10 min, test conditions 230 °C, 2.16 kg.

[0035] Polypropylene Resin 2#: Random copolymer polypropylene, UT8012M, from Maoming Petrochemical, melt index 12 g / 10 min, test conditions 230 °C, 2.16 kg.

[0036] Polypropylene Resin 3#: EP548R, from CNOOC and Shell, melt flow rate 30 g / 10 min, test conditions 230 °C, 2.16 kg.

[0037] Polypropylene Resin 4#: BX3920, from SK of Korea, melt flow rate 100 g / 10 min, test conditions 230 °C, 2.16 kg.

[0038] Low-melting-point glass powder 1#: GT40, melting point 400 °C, from Guangzhou Gelinger New Materials Co., Ltd.

[0039] Low-melting-point glass powder 2#: GT45, melting point 450 °C, from Guangzhou Gelinger New Materials Co., Ltd.

[0040] Low-melting-point glass powder 3#: FD66A, melting point 500 °C, from Anmiweina New Materials Co., Ltd.

[0041] Low-melting-point glass powder 4#: GT55, melting point 550 °C, from Guangzhou Gelinger New Materials Co., Ltd.

[0042] Low-melting-point glass powder 5#: FD76A, melting point 600 °C, from Anmiweina New Materials Co., Ltd.

[0043] Low-melting-point glass powder 6#: GT70, melting point 700 °C, from Guangzhou Gelinger New Materials Co., Ltd.

[0044] Low melting point glass powder 7#, GT90, with a melting point of 900 °C, Guangzhou Gelinger New Materials Co., Ltd.

[0045] EVOH 1#, M100B, with a melt index of 2.2 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 24 mol%.

[0046] EVOH 2#, ET3803, with a melt index of 3.2 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 38 mol%.

[0047] EVOH 3#, L171B, with a melt index of 4 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 27 mol%.

[0048] EVOH 4#, ET3808, with a melt index of 8 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 38 mol%.

[0049] EVOH 5#, SP434A, with a melt index of 11 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 32 mol%.

[0050] EVOH 6#, G156B, with a melt index of 15 g / 10 min at 210 °C and 2.16 kg, and an ethylene content of 48 mol%.

[0051] EVA 1#, EVA1802, with a melt index of 2 g / 10 min at 190 °C and 2.16 kg, and a vinyl acetate content of 18 wt%.

[0052] EVA 2#, EVA102, with a melt index of 1.5 g / 10 min at 190 °C and 2.16 kg, and a vinyl acetate content of 14 wt%.

[0053] POE, ethylene-octene copolymer, POE 5371, Exxon Chemical, with a melt mass flow rate of 10 g / 10 min.

[0054] Glass fiber, maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, antioxidant 1010, antioxidant 168, masterbatch, and lubricant are all commercially available. Unless otherwise specified, a certain component (such as masterbatch) in the parallel examples and comparative examples of the present invention is the same commercially available product.

[0055] Examples of preparing functional masterbatch are as follows:

[0056] Example 1 Preparation of functional masterbatch 1#

[0057] S1. Mix the low-melting-point glass powder 1# and vinyl silane coupling agent evenly at a mass ratio of 1:0.5 to obtain the modified low-melting-point glass powder;

[0058] S2. Take 30 parts of the modified low-melting-point glass powder, 40 parts of EVOH 1#, 20 parts of maleic anhydride grafted polypropylene, 2 parts of antioxidant, and 3 parts of lubricant from step S1, mix them evenly in a high-speed mixer, and add them to a twin-screw extruder for extrusion granulation to obtain the functional masterbatch; the rotation speed of the high-speed mixer is 150 - 200 r / min, and the temperature of the twin-screw extruder is 200 °C.

[0059] Example 2 Preparation of functional masterbatch 2#

[0060] S1. Mix the low-melting-point glass powder 2# and amino silane coupling agent evenly at a mass ratio of 1:0.6 to obtain the modified low-melting-point glass powder;

[0061] S2. Take 35 parts of the modified low-melting-point glass powder, 40 parts of EVOH 2#, 30 parts of maleic anhydride grafted polypropylene, 3 parts of antioxidant, and 3 parts of lubricant from step S1, mix them evenly in a high-speed mixer, and add them to a twin-screw extruder for extrusion granulation to obtain the functional masterbatch; the rotation speed of the high-speed mixer is 150 - 200 r / min, and the temperature of the twin-screw extruder is 190 °C.

[0062] Example 3 Preparation of functional masterbatch 3#

[0063] S1. Mix the low-melting-point glass powder 3# and methacryloxy silane coupling agent evenly at a mass ratio of 1:1 to obtain the modified low-melting-point glass powder;

[0064] S2. Take 40 parts of the modified low-melting-point glass powder, 50 parts of EVOH 3#, 25 parts of maleic anhydride grafted polypropylene, 3 parts of antioxidant, and 4 parts of lubricant from step S1, mix them evenly in a high-speed mixer, and add them to a twin-screw extruder for extrusion granulation to obtain the functional masterbatch; the rotation speed of the high-speed mixer is 150 - 200 r / min, and the temperature of the twin-screw extruder is 190 °C.

[0065] Example 4 Preparation of functional masterbatch 4#

[0066] S1. Mix the low-melting-point glass powder 4# and aluminum-titanium composite silane coupling agent evenly at a mass ratio of 1:0.8 to obtain the modified low-melting-point glass powder;

[0067] S2. Take 30 parts of the modified low-melting glass powder, 50 parts of EVOH 4#, 25 parts of maleic anhydride grafted polypropylene, 2 parts of antioxidant, and 3 parts of lubricant in step S1, mix them evenly in a high-speed mixer, and add them to a twin-screw extruder for extrusion granulation to obtain a functional masterbatch. The rotation speed of the high-speed mixer is 150 - 200 rpm, and the temperature of the twin-screw extruder is 180°C.

[0068] Example 5: Prepare functional masterbatch 5#

[0069] Use low-melting glass powder 2# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0070] Example 6: Prepare functional masterbatch 6#

[0071] Use low-melting glass powder 3# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0072] Example 7: Prepare functional masterbatch 7#

[0073] Use low-melting glass powder 4# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0074] Example 8: Prepare functional masterbatch 8#

[0075] Use low-melting glass powder 5# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0076] Example 9: Prepare functional masterbatch 9#

[0077] Use low-melting glass powder 6# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0078] Example 10: Prepare functional masterbatch 10#

[0079] Use low-melting glass powder 7# instead of low-melting glass powder 1#, and other conditions are the same as in Example 1.

[0080] Example 11: Prepare functional masterbatch 11#

[0081] Use EVOH 1# instead of EVOH 2#, and other conditions are the same as in Example 2.

[0082] Example 12: Prepare functional masterbatch 12#

[0083] Use EVOH 3# instead of EVOH 2#, and other conditions are the same as in Example 2.

[0084] Example 13: Prepare functional masterbatch 13#

[0085] Use EVOH 4# instead of EVOH 2#, and other conditions are the same as those in Example 2.

[0086] Example 14 Prepare functional masterbatch 14#

[0087] Use EVOH 5# instead of EVOH 2#, and other conditions are the same as those in Example 2.

[0088] Example 15 Prepare functional masterbatch 15#

[0089] Use EVOH 6# instead of EVOH 2#, and other conditions are the same as those in Example 2.

[0090] Comparative Example 1 Prepare functional masterbatch 16#

[0091] The difference from Example 1 is that the vinyl silane coupling agent is omitted, and the others are the same as those in Example 1.

[0092] Comparative Example 2 Prepare functional masterbatch 17#

[0093] The difference from Example 1 is that the low melting point glass powder is omitted, and the ethylene-vinyl alcohol copolymer and maleic anhydride grafted polypropylene copolymer are mixed and melt extruded to prepare the functional masterbatch, and the others are the same as those in Example 1.

[0094] Comparative Example 3 Prepare functional masterbatch 18#

[0095] The difference from Example 1 is that the ethylene-vinyl alcohol copolymer is omitted, and the others are the same as those in Example 1.

[0096] The components and parts by weight of the polypropylene composites of Examples A1 - A18 and Comparative Examples B1 - B6 are selected as shown in Tables 1, 2, 3, and 4. Among them, the preparation method of the polypropylene composites of Examples A1 - A18 and Comparative Examples B1 - B6 includes the following steps:

[0097] (1) Weigh various raw materials according to the ratio;

[0098] (2) Add the above raw materials into a mixer and mix evenly to obtain a mixed material; the temperature of the mixer is 50 - 70°C, and the rotation speed of the mixer is 100 - 150 r / min;

[0099] (3) Add the mixed material obtained in step (2) into a twin-screw extruder for extrusion granulation. The temperatures of the twin-screw extruder from the feeding section to the head are as follows: 150 - 160°C, 170 - 180°C, 190 - 200°C, 190 - 200°C, 190 - 210°C, 190 - 220°C, 190 - 220°C, the screw rotation speed is 450 r / min, and the screw length-diameter ratio is 48:1 to obtain the polypropylene composite material.

[0100] Table 1 Allocation ratios (parts by weight) of each group in Examples A1 - A7.

[0101]

[0102] Table 2 Allocation ratios (parts by weight) of each group in Examples A8 - A13.

[0103]

[0104] Table 3 Allocation ratios (parts by weight) of each group in Examples A14 - A18.

[0105]

[0106] Table 4 Allocation ratios (parts by weight) of each group in Comparative Examples B1 - B6.

[0107]

[0108] Performance test.

[0109] The polypropylene composites prepared in Examples A1 - A18 and Comparative Examples B1 - B6 were subjected to relevant performance tests. The specific test methods are as follows:

[0110] (1) Tensile strength test: The tensile strength of the polypropylene composition material was tested according to ISO 527 - 2012 "Test Method for Tensile Properties of Plastics", and the tensile rate was 50 mm / min.

[0111] (2) Izod notched impact strength test: Conducted according to ISO180 standard.

[0112] (3) Elongation at break: ISO 527 - 1 - 2019: Test conditions: 23°C.

[0113] (4) Heat - resistant and antioxidant aging performance test: The tensile specimen was placed in a precision aging test chamber with a temperature set at 150°C for accelerated aging. After 1000 h, it was taken out and conditioned in an environment of 23°C and 50% RH for 24 hours. Then, the tensile test was carried out according to ISO527 - 2 standard, and the tensile speed was 10 mm / min. The retention rate of tensile strength after aging (Retention rate = Tensile strength after aging / Initial tensile strength * 100%) was used as the judgment basis.

[0114] (5) Test of barrier properties. For oxygen permeability coefficient, refer to GB / T1038 - 2000; for water vapor permeability coefficient, refer to GB / T1037 - 2000.

[0115] The test results are shown in Table 5:

[0116] Table 5 Test results.

[0117]

[0118] As can be seen from the results in Table 5, the polypropylene composite material prepared by the present invention not only exhibits excellent thermal aging resistance, which is crucial for extending the service life of the material; but also has extremely low permeability coefficients for oxygen and water vapor, capable of effectively isolating moisture and oxygen and protecting the internal structure from the external environment. In addition, this polypropylene composite material also has excellent tensile strength and good elongation at break, and particularly has very good low-temperature impact performance, which enables it to maintain stability in extreme environments and is an ideal material choice for manufacturing cables.

[0119] By comparing the results of Comparative Example A1 with those of Examples A8 - A13, it can be found that the melting point of the low-melting glass powder has no significant effect on the tensile strength, elongation at break, and impact strength of the polypropylene composite material. However, the melting point has an important impact on the high-temperature aging resistance and barrier properties of the material. Specifically, the polypropylene composite materials prepared with glass powder having a melting point in the range of 450 - 600 °C (i.e., Examples A8 to A12) exhibit more superior high-temperature aging resistance and barrier properties. This indicates that in the preparation process of the polypropylene composite material, selecting an appropriate melting point of the low-melting glass powder is crucial for improving the material's performance and barrier effect in high-temperature environments.

[0120] By comparing the results of Example A2 with those of Examples A14 to A18, it can be found that the melt flow rate and ethylene content of the ethylene-vinyl alcohol copolymer have no obvious effect on the tensile strength, elongation at break, and impact strength of the polypropylene composite material. However, these factors have a significant impact on the heat-oxidative aging resistance and barrier properties of the material. Specifically, in Example A2 and Examples A15 to A17, the polypropylene composite materials prepared using an ethylene-vinyl alcohol copolymer with a melt flow rate of 3.2 - 11 g / 10 min and an ethylene content of 27 - 38 mol% exhibit more superior high-temperature aging resistance and barrier properties. This difference may be due to the different ethylene contents in the ethylene-vinyl alcohol copolymer, which change the surface polarity of the polypropylene material and thus affect its heat aging resistance.

[0121] The results of comparing Example A1 with Comparative Examples B1 - B3 show that the polypropylene composites in Comparative Examples B1 - B3 do not contain coupling agents, low - melting - point glass powder, and ethylene - vinyl alcohol copolymer. These differences have little impact on the tensile strength and elongation at break of the materials. However, the composites lacking these additives show a significant decline in low - temperature toughness, heat - aging resistance, and barrier properties. The low - melting - point glass powder modified by the coupling agent has better dispersion in the polymer, thus improving the low - temperature toughness, heat - aging resistance, and barrier properties of the material. In contrast, due to the lack of low - melting - point glass powder or ethylene - vinyl alcohol copolymer in Comparative Examples B2 - B3, their low - temperature toughness, heat - aging resistance, and barrier properties are significantly reduced. This indicates that the functional masterbatch made of coupling agent, low - melting - point glass powder, and ethylene - vinyl alcohol copolymer is crucial for improving the overall performance of polypropylene composites.

[0122] The results of comparing Example A1 with Comparative Examples B4 - B6 show that without adding EVA, compatibilizer, and functional masterbatch, the polypropylene composites in Comparative Examples B4 - B6 show a significant decline in low - temperature toughness, heat - aging resistance, and barrier properties. This indicates that the use of the compatibilizer in this application improves the dispersion of EVA and functional masterbatch in the polypropylene composite, promotes the uniform distribution of each component, and significantly enhances the overall performance of the material.

[0123] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0124] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0125] As described above, the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various changes or substitutions, and these should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A polypropylene composite material for wires and cables, characterized in that: The polypropylene composite material comprises the following raw materials in parts by weight: 55-85 parts of polypropylene, 5-15 parts of ethylene-octene copolymer, 20-30 parts of ethylene-vinyl acetate copolymer, 10-20 parts of functional masterbatch, 10-20 parts of compatibilizer, 20-40 parts of glass fiber, 0.1-3 parts of antioxidant, 0.5-5 parts of masterbatch, and 1-5 parts of lubricant; The functional masterbatch is prepared by the following method: S1. Mixing low-melting-point glass powder and coupling agent in a mass ratio of 1:0.5-1 to obtain modified low-melting-point glass powder; S2. Take 30-40 parts of the modified low-melting-point glass powder in step S1, 30-50 parts of ethylene-vinyl alcohol copolymer, 20-30 parts of maleic anhydride grafted polypropylene, and 2-8 parts of processing aid, mix them evenly in a high-speed mixer, and then add them into a twin-screw extruder for extrusion and granulation to obtain a functional masterbatch.

2. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The coupling agent in step S1 includes one or more of vinyl silane coupling agent, amino silane coupling agent, methacryloxy silane coupling agent, titanate coupling agent, and aluminum-titanium composite silane coupling agent.

3. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The ethylene-vinyl alcohol copolymer has a melt flow rate of 2-20 g / 10 min at 210° C. and 2.16 kg, and an ethylene content of 24-48 mol %.

4. The polypropylene composite material according to claim 1, characterized in that: The melting point of the low-melting-point glass powder is 500°C-700°C.

5. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The processing aid in step S2 is at least one of an antioxidant and a lubricant.

6. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The polypropylene is homopolymer polypropylene or propylene-ethylene copolymer, and the melting index of the polypropylene resin under the test conditions of 230° C. and 2.16 kg is 10-100 g / 10 min.

7. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The compatibilizer is at least one of maleic anhydride grafted polypropylene and maleic anhydride grafted polyethylene; the glass fiber is short-cut glass fiber with a length of 5-10 mm.

8. The polypropylene composite material for wires and cables according to claim 1, characterized in that: The melt index of the ethylene-vinyl acetate copolymer at 190° C. and 2.16 kg is 1-3 g / 10 min, and the vinyl acetate content is 14-18 wt %; the antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant; the lubricant includes one or more of erucamide, oleamide, EBS amide, PE wax, and stearate.

9. A method for preparing the polypropylene composite material for wires and cables as claimed in any one of claims 1 to 8, comprising the following steps: (1) Weigh various raw materials according to the ratio; (2) adding the above raw materials into a mixer and mixing them evenly to obtain a mixed material; the temperature of the mixer is 50-70° C. and the speed of the mixer is 100-150 r / min; (3) adding the mixture obtained in step (2) into a twin-screw extruder for extrusion granulation to obtain the polypropylene composite material.

10. A power cable, comprising a conductor, a modified barrier layer and an outer sheath arranged in sequence from the inside to the outside; the modified barrier layer is a modified polypropylene layer, and the modified polypropylene layer is prepared from the polypropylene composite material for wires and cables according to any one of claims 1 to 8.

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