Flame-retardant PP cable insulating material and preparation method thereof

Abstract

The invention relates to the technical field of cable materials, in particular to a flame-retardant PP cable insulating material and a preparation method thereof. The flame-retardant PP cable insulating material comprises the following components in parts by weight: 18.0-26.0 parts of polypropylene resin; 10.0 to 18.0 parts of a toughening agent; 45.0 to 50.0 parts of a flame retardant; 10.0 to 15.0 parts of a flame retardant synergist; 1.5 to 2.0 parts of nano fumed silica; 0.05 to 0.15 part of an antioxidant; 1.5 to 2.5 parts of a lubricant; 0.6 to 1.4 parts of color master batch; 1.0 to 2.5 parts of lignin-based carbon microspheres; and 0.8 to 1.8 parts of polyetherimide. The flame-retardant PP cable insulating material provided by the invention has high flame-retardant property and high mechanical property, and further popularization and application of the PP material in the field of cables are widened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable materials, and particularly relates to a flame-retardant PP cable insulation material and a preparation method thereof. BACKGROUND

[0002] In the field of wire and cable, polypropylene (PP) has become an important insulation and sheath material due to its excellent properties. As a thermoplastic resin, its long-term use temperature can reach 120 DEG C, which can meet the demand of stable operation of the cable at a higher temperature; and it has high mechanical strength without crosslinking treatment, which simplifies the production process and also realizes recycling of the insulation material after the cable is scrapped, which is in line with the global green environmental protection and energy saving concept, and is widely used in medium and low voltage distribution cables, overhead insulated cables and rail transit cables and other scenes, and is one of the key materials for promoting the sustainable development of the cable industry.

[0003] However, the PP material has a significant defect, which is a flammable material with an oxygen index (LOI) of only 17-18, belonging to the flammable grade, and cannot meet the requirements of the cable field for flame retardant performance. In order to make the PP cable material meet the industry flame retardant standards such as UL94 V-0 and GB / T18380 bundled burning A grade, a large amount of flame retardant agent needs to be added, such as bromine-based decabromodiphenyl ethane, phosphorus-based flame retardant and flame retardant synergist Sb2O3. However, high addition amount of flame retardant agent will cause new problems, resulting in serious deterioration of the mechanical properties of the PP cable material, and forming a "contradictory balance" problem of flame retardant performance and mechanical properties. When the total addition amount of the flame retardant is more than 40%, the elongation at break of the material is greatly reduced, and the elongation at break of some formula products is only 20%, which is far lower than the level of more than 300% of crosslinked polyethylene (XLPE); at the same time, the low temperature impact performance is deteriorated, and it is easy to be brittle in the environment below-20 DEG C, which is difficult to meet the cable laying demand in cold regions and the bending use requirement in mobile scenes such as drag chain cable. At present, it is difficult to find a balance point between "high flame retardant (LOI≥32)" and "high toughness (elongation at break≥100%) " in the industry, and the existing PP cable material either meets the flame retardant performance but has insufficient mechanical properties, or has qualified mechanical properties but cannot meet the flame retardant standards, which seriously limits the further popularization and application of PP material in the field of cable.

[0004] To address this issue, existing technologies have explored various solutions. Some solutions employ novel flame retardants, such as phosphorus-nitrogen synergistic flame retardants, aiming to maintain flame retardancy while reducing the amount added. However, these flame retardants are costly and have poor compatibility with the PP matrix, leading to uneven dispersion and making it difficult to balance flame retardancy and mechanical properties. Another solution increases the proportion of toughening agents in the formulation, such as increasing the amount of POE elastomer to improve mechanical properties, but this results in a decrease in the material's flame retardancy, failing to meet industry standards. Still other technologies attempt to alleviate the performance conflict by optimizing processing parameters, such as adjusting extrusion temperature and screw speed, but the effects are limited, failing to fundamentally solve the core problem of the difficulty in balancing flame retardancy and mechanical properties in PP cable materials.

[0005] Therefore, it is necessary to further develop new solutions to address the problem that the flame retardant and mechanical properties of the aforementioned PP cable materials cannot simultaneously meet the requirements. Summary of the Invention

[0006] This application provides a flame-retardant PP cable insulation material and its preparation method. The flame-retardant PP cable insulation material provided by this application possesses both high flame-retardant properties and high mechanical properties, thus broadening the further promotion and application of PP materials in the cable field.

[0007] In the first aspect, this application provides a flame-retardant PP cable insulation material, which adopts the following technical solution:

[0008] A flame-retardant PP cable insulation material, the flame-retardant PP cable insulation material comprising the following components in parts by weight:

[0009] 18.0-26.0 parts of polypropylene resin;

[0010] Toughening agent 10.0-18.0 parts;

[0011] Flame retardant 45.0-50.0 parts;

[0012] Flame retardant synergist 10.0-15.0 parts;

[0013] 1.5-2.0 parts of nano-fumed silica;

[0014] Antioxidant 0.05-0.15 parts;

[0015] 1.5-2.5 parts lubricant;

[0016] 0.6-1.4 parts of color masterbatch;

[0017] 1.0-2.5 parts of lignin-based carbon microspheres;

[0018] 0.8-1.8 parts of polyetherimide.

[0019] Polypropylene resin is a thermoplastic resin formed by the polymerization reaction of propylene monomers. Its core function is to serve as the matrix resin (skeleton) of materials, determining the basic shape, insulation properties and recyclability of materials.

[0020] Toughening agents can be polyolefin elastomers. Polyolefin elastomers are copolymers of ethylene and α-olefins (such as octene), belonging to flexible elastomer materials. Their core function is to improve the toughness and impact resistance of the PP matrix, solving the defect of pure PP material being "highly rigid but brittle".

[0021] Flame retardants can include decabromodiphenyl ethane. Decabromodiphenyl ethane is a bromine-based flame retardant (an organic compound containing bromine), with the molecular formula C1. 14 H4Br 10 It is free of dioxin-like harmful impurities (more environmentally friendly than traditional decabromodiphenyl ether) and has good thermal stability (decomposition temperature above 280℃, suitable for PP processing temperature). Its core function is to provide the main flame retardant effect of the material, and it is the key component to achieve "LOI 38 (limiting oxygen index 38%, far exceeding the flame retardant qualification standard LOI≥26%)".

[0022] Antimony trioxide can be used as a flame retardant synergist. Antimony trioxide does not have independent flame retardant capabilities and must be used in conjunction with bromine-based or chlorine-based flame retardants. Its core function is to enhance the flame retardant efficiency of decabromodiphenyl ethane, reduce the total amount of flame retardant required, and simultaneously improve the density of the charred layer.

[0023] Nano-sized fumed silica is produced by the high-temperature hydrolysis of raw materials such as silicon tetrachloride to form nano-sized silicon dioxide (SiO2). Its particle size is typically 5-50 nm, and it has a large specific surface area (>100 nm). 2 It contains hydroxyl groups on its surface and has good dispersibility. Its core function is to improve the mechanical strength (tensile strength, flexural modulus) and aging resistance of materials, while also helping to improve the dispersibility of flame retardants.

[0024] The antioxidant specifically is Antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]), a hindered phenolic primary antioxidant (its chemical name is relatively long; the industry-standard designation is "1010"). It is a white powder with good thermal stability (decomposition temperature > 240℃, suitable for PP processing temperatures). Its core function is to delay the thermo-oxidative aging of materials and prevent cable degradation during long-term high-temperature (120℃) use or processing.

[0025] Polypropylene wax, used as a lubricant, is made from low-molecular-weight polypropylene (typically 1000-10000 molecular weight) obtained by high-temperature pyrolysis or polymerization modification of polypropylene resin. It is a waxy solid that combines lubricity and compatibility. Its core function is to improve the processing flowability of the material, reduce frictional resistance during extrusion, and ensure smooth cable extrusion molding.

[0026] The color masterbatch is a black masterbatch. The black masterbatch uses PP or PE as the carrier resin and uniformly disperses carbon black (black pigment), dispersant and other components. Its core function is to give the cable material a black appearance, while providing resistance to ultraviolet (UV) aging.

[0027] The PP cable insulation material provided in this application also incorporates lignin-based carbon microspheres (1-5 μm in diameter, prepared by high-temperature carbonization) and polyetherimide (PEI, low molecular weight, Mw = 5000-10000). Lignonin-based carbon microspheres are bio-based materials with renewable sources, currently mainly used in adsorption applications, and have not been seen in cable materials. PEI is a high-temperature resistant engineering plastic, currently mainly used in high-end electronics, and its application as a modifier in PP cable materials is extremely rare. The simultaneous addition of lignin-based carbon microspheres and polyetherimide to the PP cable insulation material can further improve its flame retardant and mechanical properties.

[0028] Furthermore, lignin-based carbon microspheres, being carbonaceous in structure, do not melt or drip at high temperatures, allowing them to fill the pores of the PP carbon layer, increasing its density, and their low density prevents material weight gain. The aromatic rings of polyetherimide readily form a carbon layer at high temperatures (high carbonization rate), and its decomposition temperature exceeds 450℃, thus improving the thermal stability of PP.

[0029] Optionally, the lignin-based carbon microspheres are 1.5-2.0 parts by weight.

[0030] In one specific embodiment, the lignin-based carbon microspheres are present in parts by weight of 1.0 parts, 1.5 parts, 1.8 parts, 2.0 parts, and 2.5 parts.

[0031] In some specific embodiments, the lignin-based carbon microspheres are present in the following weight proportions: 1.0-1.5 parts, 1.0-1.8 parts, 1.0-2.0 parts, 1.5-1.8 parts, 1.5-2.0 parts, 1.5-2.5 parts, 1.8-2.0 parts, 1.8-2.5 parts, and 2.0-2.5 parts.

[0032] Optionally, the polyetherimide is present in 1.1-1.5 parts by weight.

[0033] In one specific embodiment, the polyetherimide is present in parts by weight of 0.8 parts, 1.1 parts, 1.3 parts, 1.5 parts, and 1.8 parts.

[0034] In some specific embodiments, the polyetherimide is present in parts by weight of 0.8-1.1 parts, 0.8-1.3 parts, 0.8-1.5 parts, 1.1-1.3 parts, 1.1-1.5 parts, 1.1-1.8 parts, 1.3-1.5 parts, 1.3-1.8 parts, or 1.5-1.8 parts.

[0035] Optionally, the flame-retardant PP cable insulation material further includes graphene quantum dots; the graphene quantum dots are present in 1.2-2.0 parts by weight.

[0036] Optionally, the graphene quantum dots are present in 1.4-1.8 parts by weight.

[0037] In one specific embodiment, the graphene quantum dots are present in weight parts of 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, and 2.0 parts.

[0038] In some specific embodiments, the graphene quantum dots are present in weight parts of 1.2-1.4 parts, 1.2-1.6 parts, 1.2-1.8 parts, 1.4-1.6 parts, 1.4-1.8 parts, 1.4-2.0 parts, 1.6-1.8 parts, 1.6-2.0 parts, and 1.8-2.0 parts.

[0039] The PP cable insulation material provided in this application also incorporates graphene quantum dots. Graphene quantum dots have good water solubility, an average particle size between 5-10 nm, and a surface rich in functional groups such as carboxyl groups. The inclusion of graphene quantum dots further enhances the flame retardant and mechanical properties of the PP cable insulation material.

[0040] Secondly, this application also provides a method for preparing flame-retardant PP cable insulation material, using the following technical solution:

[0041] A method for preparing flame-retardant PP cable insulation material, the method specifically includes the following steps:

[0042] Premix: According to the formula, add polypropylene resin, toughening agent, flame retardant, flame retardant synergist, nano fumed silica, antioxidant, lubricant, color masterbatch, lignin-based carbon microspheres, polyetherimide, and graphene quantum dots to a high-speed mixer and stir at high speed to obtain a premix.

[0043] Melt blending and granulation: The premixed material is fed into a twin-screw extruder, with the screw speed controlled at 300-350 r / min, the melt temperature at 190-240℃, the nozzle temperature at 220-240℃, the front section temperature at 220-235℃, the middle section temperature at 210-230℃, and the rear section temperature at 190-220℃, so that the components can be fully dispersed and melt-blended; the extruded molten material is water-cooled and then cut into granules of 2-3 mm in length to obtain flame-retardant PP cable material masterbatch;

[0044] Cable forming: The flame-retardant PP cable material masterbatch is fed into a cable extruder with a screw speed of 50-150 r / min; the extruded material is shaped by a cooling water tank to obtain the finished flame-retardant PP cable material.

[0045] In summary, this application includes at least one of the following beneficial technical effects:

[0046] The flame-retardant PP cable insulation material provided in this application not only has high flame-retardant properties but also high mechanical properties, thus broadening the further promotion and application of PP materials in the cable field. Detailed Implementation

[0047] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0048] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0049] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0050] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0051] This application provides a flame-retardant PP cable insulation material comprising the following components in parts by weight: 18.0-26.0 parts of polypropylene resin; 10.0-18.0 parts of toughening agent; 45.0-50.0 parts of flame retardant; 10.0-15.0 parts of flame retardant synergist; 1.5-2.0 parts of nano-fumed silica; 0.05-0.15 parts of antioxidant; 1.5-2.5 parts of lubricant; 0.6-1.4 parts of color masterbatch; 1.0-2.5 parts of lignin-based carbon microspheres; and 0.8-1.8 parts of polyetherimide.

[0052] This application also provides a method for preparing the above-mentioned flame-retardant PP cable insulation material, which specifically includes the following steps:

[0053] Premix: According to the formula, add polypropylene resin, toughening agent, flame retardant, flame retardant synergist, nano fumed silica, antioxidant, lubricant, color masterbatch, lignin-based carbon microspheres, polyetherimide, and graphene quantum dots to a high-speed mixer and stir at high speed to obtain a premix.

[0054] Melt blending and granulation: The premixed material is fed into a twin-screw extruder, with the screw speed controlled at 300-350 r / min, the melt temperature at 190-240℃, the nozzle temperature at 220-240℃, the front section temperature at 220-235℃, the middle section temperature at 210-230℃, and the rear section temperature at 190-220℃, so that the components can be fully dispersed and melt-blended; the extruded molten material is water-cooled and then cut into granules of 2-3 mm in length to obtain flame-retardant PP cable material masterbatch;

[0055] Cable forming: The flame-retardant PP cable material masterbatch is fed into a cable extruder with a screw speed of 50-150 r / min; the extruded material is shaped by a cooling water tank to obtain the finished flame-retardant PP cable material.

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0057] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0058] In the following examples, the polypropylene resin is specifically PP 531N; the toughening agent is specifically POE5070D (polyolefin elastomer 5070D); the flame retardant is specifically DBDPE (decabromodiphenyl ethane); the flame retardant synergist is specifically Sb2O3 (antimony trioxide); the antioxidant is specifically antioxidant 1010; the lubricant is specifically PP wax (polypropylene wax); the color masterbatch is specifically (black masterbatch 2014B); and the polyetherimide is specifically ULTEM. TM 1000; the graphene quantum dot is specifically XF-GQD-01 (Nanjing Xianfeng Nanomaterials Technology Co., Ltd.).

[0059] The preparation method of lignin-based carbon microspheres is as follows: Lignosulfonate was used as raw material, and lignin-based carbon microspheres were prepared by hydrothermal reaction at 230℃ for 12 hours. The microspheres had a particle size of 5-7 μm and exhibited good electrochemical performance, with a reversible specific capacity of 389.4 mAh / g at 0.1C charge / discharge, a capacity of 180 mAh / g at 1C charge / discharge, and a capacity retention of 97.8% after 100 cycles at 1C.

[0060] The present application will be further described in detail below with reference to the embodiments and test results.

[0061] Example 1

[0062] This embodiment provides a flame-retardant PP cable insulation material.

[0063] The preparation method of this material specifically includes the following steps:

[0064] (1) Raw material pretreatment

[0065] Place the PP resin (PP 531N) into a drying device, set the drying temperature to 80-90℃, and dry for 2-4 hours to remove moisture from the resin particles. This prevents air bubbles from forming due to moisture during subsequent processing, which could affect the insulation performance and appearance quality of the cable material.

[0066] Meanwhile, if the flame retardant (decabromodiphenyl ethane) and flame retardant synergist (Sb2O3) clump together, they need to be crushed using a pulverizer and passed through an 80-100 mesh sieve to ensure particle uniformity and facilitate subsequent mixing and dispersion.

[0067] (2) Premixing

[0068] According to the formula ratio, the dried PP resin, toughening agent (POE 5070D), pretreated flame retardant, flame retardant synergist, nano-fumed silica, antioxidant (1010), lubricant (PP wax), color masterbatch (black masterbatch 2014B), lignin-based carbon microspheres, polyetherimide, and graphene quantum dots are added to a high-speed mixer. Under high-speed stirring, the small molecule additives (antioxidant, lubricant, etc.) are uniformly adhered to the surface of the resin particles, preparing for subsequent melt blending, and a premix is ​​obtained.

[0069] (3) Melt blending granulation

[0070] Equipment and temperature settings: A twin-screw extruder is used for melt blending and granulation.

[0071] Based on the processing parameters, the melt temperature of the extruder is set to 190-240℃, and the temperatures of different sections of the extruder (front, middle, and rear sections) and the nozzles are precisely controlled. Specifically, the nozzle temperature is 220-240℃, the front section temperature is 220-235℃, the middle section temperature is 210-230℃, and the rear section temperature is 190-220℃.

[0072] By setting a reasonable temperature gradient, we can ensure that all raw materials are fully mixed in the molten state, while avoiding the damage of high temperature to the effectiveness of components such as flame retardants.

[0073] Extrusion and Granulation: The premixed material is fed into a twin-screw extruder, with the screw speed controlled at 300-350 r / min. Utilizing the shearing action of the screw and the set high temperature, the components are fully dispersed and melt-blended. The extruded molten material is then water-cooled and cut into 2-3 mm long particles by a pelletizer to obtain flame-retardant PP cable material masterbatch.

[0074] (4) Cable forming

[0075] Equipment and temperature settings: Cable forming is performed using a single-screw cable extruder.

[0076] Adjust the extrusion die according to the thickness requirements of the cable insulation or sheath layer, and set the extruder temperature according to the processing parameters. The temperature range should match the melting and injection temperatures of the granulation process to ensure that the material has good fluidity.

[0077] Extrusion and Shaping: The flame-retardant PP cable material masterbatch is fed into a single-screw cable extruder. The screw speed is matched according to the production line speed, usually between 50-150 r / min. The extruded material is shaped in a cooling water tank to finally obtain the finished flame-retardant PP cable material.

[0078] The components and their proportions in this material are detailed in Table 1.

[0079] Table 1. Components and proportions of flame-retardant PP cable materials in each embodiment and comparative example.

[0080]

[0081]

[0082] Example 2-14

[0083] Examples 2-14 each provide a flame-retardant PP cable insulation material. The difference between these examples and Example 1 lies in the addition of lignin-based carbon microspheres, polyetherimide, and graphene quantum dots, as shown in Table 1. All other operational steps remain consistent with Example 1.

[0084] Specifically, the differences between Examples 1-14 are as follows:

[0085] The difference between Examples 1-5 is the amount of lignin-based carbon microspheres added.

[0086] The difference between Examples 3 and 6-9 is the amount of polyetherimide added.

[0087] The difference between Examples 3 and 10-14 is whether or not graphene quantum dots are added and the amount of graphene quantum dots added.

[0088] Comparative Examples 1-3

[0089] Comparative Examples 1-3 each provide a flame-retardant PP cable insulation material. The difference between the above comparative examples and Example 3 lies in the addition of lignin-based carbon microspheres and polyetherimide, as shown in Table 1. All other operating steps remain consistent with Example 3.

[0090] Specifically, the difference between Comparative Example 1 and Example 3 is that no lignin-based carbon microspheres and polyetherimide were added.

[0091] The difference between Comparative Example 2 and Example 3 is that only lignin-based carbon microspheres were added.

[0092] The difference between Comparative Example 3 and Example 3 is that only polyetherimide was added.

[0093] Comparative Examples 4-6

[0094] Comparative Examples 4-6 each provide a flame-retardant PP cable insulation material. The difference between these comparative examples and Example 12 lies in the addition of lignin-based carbon microspheres, polyetherimide, and graphene quantum dots, as shown in Table 1. All other operational steps remain consistent with Example 12.

[0095] Specifically, the difference between Comparative Example 4 and Example 12 is that only graphene quantum dots were added.

[0096] The difference between Comparative Example 5 and Example 12 is that only lignin-based carbon microspheres and graphene quantum dots were added.

[0097] The difference between Comparative Example 6 and Example 12 is that only polyetherimide and graphene quantum dots were added.

[0098] Performance test results

[0099] (I) Flame retardant properties

[0100] The flame-retardant performance of the flame-retardant PP cable insulation materials of the above embodiments and comparative examples was tested respectively.

[0101] The specific testing items and methods are as follows:

[0102] (1) Oxygen Index (LOI) - GB / T 2406.2-2009. The material is made into a standard sample (80-150mm long, 10mm wide, and 4mm thick), placed in an oxygen index meter, and the oxygen-nitrogen mixture ratio is adjusted to determine the minimum oxygen concentration required for the material to maintain combustion. Flame-retardant PP cable materials usually require LOI≥32 (high flame-retardant grade).

[0103] (2) Vertical burning (UL94) - UL 94-2021, the sample is fixed vertically and ignited with a specified flame (10mm flame height) for 10s. After the flame is removed, the extinguishing time is recorded. If the sample reignites after the first extinguishing, it is ignited again for 10 seconds. The total burning time is ≤50s and there are no drips that ignite the degreased cotton below. It is judged to be V-0 grade (a common flame retardant grade for cables).

[0104] (3) Bundle burning - GB / T 18380.31-2008, seven 1m long flame-retardant PP cable samples are bundled and fixed, ignited with a 4kW flame for 20min, and the carbonization length of the samples is measured after cooling; if the carbonization length is ≤2.5m (bundle burning grade A), it is determined to meet the requirements of cable trunk line or vertical laying scenario.

[0105] According to the GB / T 18380 series of standards, "Burn Tests of Cables and Optical Fibers under Flame Conditions," bundled burning tests are divided into four levels: A, B, C, and D. These tests evaluate the ability of vertically installed bundled wires, cables, or optical fibers to suppress the vertical spread of flames under specified conditions. Details are as follows:

[0106] Grade A – High volume content of non-metallic materials, many (≤7) wires vertically installed together, ignition time 40 minutes, qualification criteria: the carbonization range on the sample should not exceed 2.5m above the bottom edge of the blowtorch.

[0107] Grade B – Medium volume content of non-metallic materials, a relatively large number (≤3.5) of wires installed vertically together, ignition time 40 minutes, qualification criteria: the carbonization range on the sample should not exceed 2.5m above the bottom edge of the blowtorch.

[0108] Grade C – Low volume content of non-metallic materials, multiple (≤1.5) wires installed vertically together, ignition time 20 minutes, qualification criteria: the carbonization range on the sample should not exceed 2.5m above the bottom edge of the blowtorch.

[0109] Grade D – Low volume content of non-metallic materials, a small number (≤0.5) of wires installed vertically together, ignition time 20 minutes, qualification criteria: the carbonization range on the sample should not exceed 2.5m above the bottom edge of the blowtorch.

[0110] The test results are shown in Table 2.

[0111] Table 2. Test results of flame retardant and mechanical properties

[0112]

[0113]

[0114] Table 2 shows that, comparing the test results of Examples 1-5, controlling the addition amount of lignin-based carbon microspheres to 1.0-2.5 parts can effectively improve the flame-retardant performance of the flame-retardant PP cable material. Furthermore, comparing the test results of Examples 3 and 6-9, controlling the addition amount of polyetherimide to 0.8-1.8 parts can effectively improve the flame-retardant performance of the flame-retardant PP cable material. And comparing the test results with those of Comparative Examples 1-3, it is clear that, compared to adding lignin-based carbon microspheres or polyetherimide alone, adding both lignin-based carbon microspheres and polyetherimide simultaneously is more effective in improving the flame-retardant performance of the flame-retardant PP cable material.

[0115] Comparing the test results of Examples 3 and 10-14, it is evident that adding graphene quantum dots in addition to lignin-based carbon microspheres and polyetherimide further enhances the flame-retardant properties of the flame-retardant PP cable material. Furthermore, comparing the test results with those of Comparative Examples 4-6 shows that, compared to adding graphene quantum dots alone or simultaneously adding graphene quantum dots with lignin-based carbon microspheres or polyetherimide, adding graphene quantum dots in addition to lignin-based carbon microspheres and polyetherimide is more effective in improving the flame-retardant properties of the flame-retardant PP cable material.

[0116] (II) Mechanical Properties

[0117] Mechanical properties of the flame-retardant PP cable insulation materials of the above embodiments and comparative examples were tested respectively.

[0118] The specific testing items and methods are as follows:

[0119] (1) Tensile strength and elongation at break — GB / T 1040.3-2006, the flame-retardant PP cable material is made into dumbbell-shaped specimens (Type 1 or Type 2), and stretched at a speed of 50 mm / min using a tensile testing machine. The tensile force at break is recorded (to calculate the tensile strength, which is usually required to be ≥10 MPa for cable materials) and the elongation of the specimen (to calculate the elongation at break, which is required to be ≥100% for high toughness requirements).

[0120] (2) Low-temperature impact performance—GB / T 1843-2021, using a simply supported beam impact testing machine, place the specimen (80mm×10mm×4mm) in an environment of -40℃ for 2 hours, and impact it with a pendulum of specified energy to determine the impact strength; if the specimen does not fracture brittlely (impact strength ≥2kJ / m 2 It was determined that it meets the requirements for use in cold regions.

[0121] (3) Bending performance - GB / T 9341-2008, place the sample (80mm×10mm×4mm) in a bending tester, apply bending force at a speed of 2mm / min, determine the bending strength (usually required to be ≥15MPa) and bending modulus, and evaluate the material's resistance to deformation during cable bending and laying.

[0122] The test results are shown in Table 2.

[0123] Table 2 shows that, based on the test results of Examples 1-5, controlling the addition amount of lignin-based carbon microspheres to 1.0-2.5 parts effectively improves the mechanical properties of flame-retardant PP cable materials. Furthermore, based on the test results of Examples 3 and 6-9, controlling the addition amount of polyetherimide to 0.8-1.8 parts effectively improves the mechanical properties of flame-retardant PP cable materials. And, comparing the test results with those of Comparative Examples 1-3, it is clear that, compared to adding lignin-based carbon microspheres or polyetherimide alone, adding both lignin-based carbon microspheres and polyetherimide is more effective in improving the mechanical properties of flame-retardant PP cable materials.

[0124] Comparing the test results of Examples 3 and 10-14, it is evident that adding graphene quantum dots in addition to lignin-based carbon microspheres and polyetherimide further improves the mechanical properties of flame-retardant PP cable materials. Furthermore, comparing the test results with those of Comparative Examples 4-6 shows that, compared to adding graphene quantum dots alone or simultaneously adding graphene quantum dots with lignin-based carbon microspheres or polyetherimide, adding graphene quantum dots in addition to lignin-based carbon microspheres and polyetherimide is more effective in improving the mechanical properties of flame-retardant PP cable materials.

[0125] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A flame-retardant PP cable insulation material, characterized in that, The flame-retardant PP cable insulation material comprises the following components in parts by weight: 18.0-26.0 parts of polypropylene resin; Toughening agent 10.0-18.0 parts; Flame retardant 45.0-50.0 parts; Flame retardant synergist 10.0-15.0 parts; 1.5-2.0 parts of nano-fumed silica; Antioxidant 0.05-0.15 parts; 1.5-2.5 parts lubricant; 0.6-1.4 parts of color masterbatch; 1.0-2.5 parts of lignin-based carbon microspheres; 0.8-1.8 parts of polyetherimide.

2. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The lignin-based carbon microspheres are 1.5-2.0 parts by weight.

3. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The polyetherimide is present in parts by weight of 1.1-1.

5.

4. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The flame-retardant PP cable insulation material also includes graphene quantum dots; the graphene quantum dots are present in 1.2-2.0 parts by weight.

5. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The graphene quantum dots are present in an amount of 1.4-1.8 parts by weight.

6. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The toughening agent is a polyolefin elastomer.

7. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The flame retardant is decabromodiphenyl ethane.

8. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The flame retardant synergist is antimony trioxide.

9. The flame-retardant PP cable insulation material according to claim 1, characterized in that, The lubricant is polypropylene wax.

10. A method for preparing the flame-retardant PP cable insulation material according to any one of claims 1-9, characterized in that, The preparation method specifically includes the following steps: Premix: According to the formula, add polypropylene resin, toughening agent, flame retardant, flame retardant synergist, nano fumed silica, antioxidant, lubricant, color masterbatch, lignin-based carbon microspheres, polyetherimide, and graphene quantum dots to a high-speed mixer and stir at high speed to obtain a premix. Melt blending and granulation: The premixed material is fed into a twin-screw extruder, with the screw speed controlled at 300-350 r / min, the melt temperature at 190-240℃, the nozzle temperature at 220-240℃, the front section temperature at 220-235℃, the middle section temperature at 210-230℃, and the rear section temperature at 190-220℃, so that the components can be fully dispersed and melt-blended; the extruded molten material is water-cooled and then cut into granules of 2-3 mm in length to obtain flame-retardant PP cable material masterbatch; Cable forming: The flame-retardant PP cable material masterbatch is fed into a cable extruder with a screw speed of 50-150 r / min; the extruded material is shaped by a cooling water tank to obtain the finished flame-retardant PP cable material.

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