A low-carbon-value halogen-free flame-retardant polypropylene composite material, a preparation method and application thereof

Abstract

The application discloses a kind of low carbon value halogen-free flame-retardant polypropylene composite materials, it is characterized in that, by weight parts, including the following components: copolymerized polypropylene 20~60 parts, organic silicon modified phytic acid piperazine compound 18~30 parts, biological base polyethylene 10~20 parts, inorganic filler 10~30 parts, the biological base polyethylene includes biological base high-density polyethylene and biological base low-density polyethylene, the ratio of biological base high-density polyethylene and biological base low-density polyethylene is 1:2~3.The low carbon value halogen-free flame-retardant polypropylene composite material of the application has excellent flame-retardant performance, and also has the mechanical performance characteristics of high modulus and high toughness, the balance of rigidity and toughness is prominent, and the GWP carbon value of composite material is significantly reduced, meets the development direction of industry carbon peak and carbon neutralization, and cost is reasonable, especially suitable for the injection molding of large-scale interior and exterior trim parts of environmental protection new energy automobile.

Description

Technical Field

[0001] This invention relates to the field of polypropylene materials technology, and more specifically, to a low-carbon-value halogen-free flame-retardant polypropylene composite material, its preparation method, and its application. Background Technology

[0002] In recent years, with the widespread adoption of new energy vehicles, the flame-retardant safety performance of automotive materials has received increasing attention. Many mainstream automakers are now requiring specific flame-retardant properties in interior and exterior trim and battery-related components, placing higher demands on the technological development of automotive materials. While traditional halogen-free flame retardants such as nitrogen-phosphorus and inorganic oxides offer excellent flame-retardant effects, their poor compatibility with the matrix resin composed of polypropylene and elastomers leads to a significant decrease in the mechanical properties of the composite materials, particularly toughness. Furthermore, the concept of low-carbon and environmental protection has gained widespread acceptance, with countries worldwide issuing their own carbon strategies. However, currently, ordinary flame-retardant polypropylene composites have high carbon values, posing significant challenges to energy and the environment. These shortcomings hinder the rapid development of halogen-free flame-retardant polypropylene materials in the automotive industry.

[0003] Existing technology discloses a flame-retardant and antistatic polypropylene composition, a flame-retardant and antistatic polypropylene material, and a method for preparing the same. The composition comprises: polypropylene, a polyolefin elastomer, an initiator, a flame retardant, an antistatic agent, and additives. Based on the total amount of the polyolefin elastomer, the mass percentage of vinyl structures in the polyolefin elastomer is 20-70%, and the mass percentage of propylene structures is 15-75%. This polypropylene composition improves the mechanical properties of the polypropylene composition, such as notched impact strength, by incorporating vinyl and propylene-structured polyolefin elastomers to induce a crosslinking reaction. However, its notched impact strength is generally only 12-20 kJ / m², resulting in limited improvement in mechanical properties, and it also has a high carbon number. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing flame-retardant polypropylene composite materials, such as poor mechanical properties and high carbon value, and to provide a low-carbon-value halogen-free flame-retardant polypropylene composite material.

[0005] The second objective of this invention is to provide a method for preparing a low-carbon, halogen-free, flame-retardant polypropylene composite material.

[0006] A third objective of this invention is to provide an application of a low-carbon, halogen-free, flame-retardant polypropylene composite material in the preparation of automotive interior and exterior trim parts.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] A low-carbon, halogen-free, flame-retardant polypropylene composite material, comprising the following components by weight:

[0009] 20-60 parts of copolymerized polypropylene, 18-30 parts of organosilicon-modified phytic acid piperazine compound, 10-20 parts of bio-based polyethylene, and 10-30 parts of inorganic filler;

[0010] The bio-based polyethylene includes bio-based high-density polyethylene and bio-based low-density polyethylene;

[0011] The ratio of bio-based high-density polyethylene to bio-based low-density polyethylene in the bio-based polypropylene is 1:2 to 3.

[0012] In the low-carbon, halogen-free flame-retardant polypropylene composite material of this invention, organosilicon-modified phytic acid piperazine compounds, as novel halogen-free flame retardants, possess excellent char-forming ability, capable of forming a stable char layer containing POC, cross-linked polyphosphate, and C=C structures, thereby isolating oxygen and heat and preventing further combustion of the material. Simultaneously, due to the presence of Si, SiO2 can be generated during combustion, further improving the quality and thermal stability of the char layer, ultimately achieving a better condensed-phase flame-retardant effect. Furthermore, phytic acid, one of the raw materials, is derived from plants and belongs to low-carbon bio-based raw materials. Bio-based high-density polyethylene (HDPE) has high rigidity, while bio-based low-density polyethylene (LDPE) has excellent toughening effect. Using the two bio-based polyethylenes in combination at a ratio of 1:2 to 3 can form rigid toughening particles in situ during processing, with bio-based HDPE as the shell and bio-based LDPE as the core. This is beneficial for achieving a balance between the rigidity and toughness of the composite material. Moreover, the bio-based polyethylene with toughening effect has a low carbon value and can replace the high-carbon-value, high-cost elastomer toughening agent in traditional halogen-free flame-retardant polypropylene material formulations. Compared with the carbon reduction scheme of using bio-based polypropylene, the carbon reduction scheme of bio-based polyethylene adopted in this invention can effectively control the cost.

[0013] In the low-carbon-value halogen-free flame-retardant polypropylene composite material of this invention, organosilicon-modified phytic acid piperazine compounds can serve as a halogen-free flame retardant. On the one hand, they provide excellent flame-retardant performance; on the other hand, the organosilicon-modified phytic acid piperazine flame retardant and the rigid toughening particles formed by bio-based HDPE / LDPE exhibit good microscopic compatibility. The soft-hard segment core-shell phase structure formed by bio-based polyethylene facilitates the compatibility of organosilicon-modified phytic acid piperazine compound molecules within it. There is no significant phase separation between the components, and the intermolecular bonding is very tight, resulting in a halogen-free flame-retardant polypropylene composite material with excellent flame-retardant properties, while also possessing high modulus and high toughness mechanical properties, demonstrating a prominent balance between rigidity and toughness. Furthermore, the silane-modified phytic acid piperazine salt flame retardant and bio-based polyethylene used in this invention are both bio-based raw materials, with significantly lower carbon values ​​than traditional halogen-free flame retardants and petroleum-based polyethylene. The composite material exhibits a significant carbon reduction effect, making it particularly suitable for injection molding of large interior and exterior automotive parts for future low-carbon and environmentally friendly applications.

[0014] In bio-based polyethylene, if the ratio of bio-based HDPE to bio-based LDPE is less than 1:3, it is difficult to form an HDPE shell structure in situ. The toughening agent is not rigid enough and cannot achieve the ideal reinforcing effect of rigid toughening particles. Furthermore, the compatibility with flame retardants is poor. If the ratio of bio-based HDPE to bio-based LDPE is greater than 1:2, the bio-based HDPE content is too high, and the toughening effect of rigid toughening particles will decrease significantly, making it impossible to balance mechanical properties.

[0015] In this invention, the melt flow rate of bio-based high-density polyethylene is 5-50 g / 10 min under test conditions of 190°C and 2.16 kg, in accordance with ISO 1133-2016 standard.

[0016] In this invention, the melt flow rate of bio-based low-density polyethylene is 5-50 g / 10 min under test conditions of 190°C and 2.16 kg, in accordance with ISO 1133-2016 standard.

[0017] The phytate piperazine compounds used in the organosilicon-modified phytate piperazine compounds of this invention are phytate piperazine salts or derivatives of phytate piperazine salts. Phytate piperazine compounds are commercially available or can be prepared using methods known in the art.

[0018] Preferably, in the preparation process of the organosilicon-modified phytic acid piperazine compound, the molar ratio of phytic acid to piperazine added in step S1 is 1 to 2:1.

[0019] Preferably, in the preparation process of the organosilicon-modified phytate piperazine compound, the molar ratio of phytate piperazine to silane coupling agent in step S2 is 1 to 2:1.

[0020] Preferably, in the preparation process of the organosilicon-modified phytic acid piperazine compound, the silane coupling agent in step S2 is at least one selected from vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltris(β-methoxyethoxy)silane. More preferably, in the preparation process of the organosilicon-modified phytic acid piperazine compound, the silane coupling agent in step S2 is vinyltrialkoxysilane.

[0021] Preferably, the reaction temperature in step S2 of the preparation process of the organosilicon-modified phytic acid piperazine compound is 40–70°C.

[0022] The appropriate content of organosilicon-modified phytic acid piperazine compounds in low-carbon-value halogen-free flame-retardant polypropylene composites can better balance the overall flame-retardant performance and system compatibility of polypropylene composites, thereby achieving a better balance between flame retardancy, mechanical properties and optimized GWP carbon value of composites.

[0023] Preferably, the organosilicon-modified phytic acid piperazine compound has a mass percentage content of 15-35% in the low-carbon-value halogen-free flame-retardant polypropylene composite material.

[0024] More preferably, the organosilicon-modified phytic acid piperazine compound has a mass percentage content of 20-25% in the low-carbon-value halogen-free flame-retardant polypropylene composite material.

[0025] Preferably, the copolymer polypropylene has a melt flow rate of 30-100 g / 10 min under the test conditions of 230°C and 2.16 kg according to the test standard ISO1133-2016.

[0026] Preferably, the inorganic filler includes at least one of talc, calcium carbonate, wollastonite, and whiskers.

[0027] The inorganic filler of the present invention has an average particle size of 1250-3000 mesh.

[0028] Preferably, based on the actual processing requirements of polypropylene materials, the halogen-free flame-retardant polypropylene composite material of the present invention further includes 0.05-5 parts by weight of processing aids.

[0029] The addition of processing aids can also increase the carbon value of composite materials to some extent, mainly because the manufacturing and transportation processes of processing aids lead to an increase in carbon value.

[0030] In specific embodiments, the processing aids include various processing aids that can be used in the art, such as one or more pigments, antioxidants, weathering agents, scratch-resistant agents, and lubricants.

[0031] In a specific embodiment, the pigment may be, for example, titanium dioxide, phthalocyanine blue, carbon black, etc.

[0032] The antioxidants may be, for example, amines, phenols, phosphites, thioesters, or other organic compounds;

[0033] The weather-resistant agent may be, for example, an amide, a hindered amine, or a silicone organic compound;

[0034] The lubricant may be, for example, stearic acid and its salts, paraffin wax, synthetic wax, etc.

[0035] The preparation method of the above-mentioned low-carbon value halogen-free flame-retardant polypropylene composite material includes the following steps:

[0036] The components are mixed evenly and then added to an extruder for melt mixing. The mixture is then granulated, cooled, and dried to obtain the low-carbon halogen-free flame-retardant polypropylene composite material.

[0037] Preferably, the temperature of the melt mixing is 170℃~240℃.

[0038] Preferably, the extruder is a twin-screw extruder or a reciprocating single-screw extruder, wherein the length-to-diameter ratio of the screw is not less than 32:1.

[0039] More preferably, the screw length-to-diameter ratio of the extruder is 32 to 40:1.

[0040] The application of the above-mentioned low-carbon halogen-free flame-retardant polypropylene composite material in the preparation of automotive interior parts.

[0041] The low-carbon-value halogen-free flame-retardant polypropylene composite material of the present invention has excellent mechanical properties, low GWP carbon value, and reasonable cost. It can be widely used in the preparation of automotive interior parts, especially large automotive interior parts, such as large interior parts for low-carbon and environmentally friendly new energy vehicles.

[0042] The organosilicon-modified phytic acid piperazine compounds of the present invention can be prepared by the following steps:

[0043] S1. Add phytic acid solution and piperazine to water in sequence, and stir to react to obtain phytic acid-piperazine solution;

[0044] S2. After adding a silane coupling agent to the phytate piperazine solution obtained in step S1, the mixture is stirred and reacted. The solvent is evaporated, the mixture is washed, and dried to obtain the organosilicon-modified phytate piperazine compound.

[0045] The specific modification mechanism of organosilicon-modified phytic acid piperazine compounds in this invention is as follows: the Si-OH formed by the hydrolysis of the hydrolyzable group in the silane coupling agent condenses with the P-OH bond in phytic acid, thereby achieving the chemical modification of phytic acid piperazine compounds by organosilicon.

[0046] The phytate piperazine compounds used in the organosilicon-modified phytate piperazine compounds of this invention are phytate piperazine salts or derivatives of phytate piperazine salts. Phytate piperazine compounds are commercially available or can be prepared using methods known in the art.

[0047] Preferably, the molar ratio of phytic acid to piperazine added in step S1 is 1 to 2:1.

[0048] Preferably, the molar ratio of phytate piperazine to silane coupling agent in step S2 is 1 to 2:1.

[0049] Preferably, the silane coupling agent in step S2 is vinyltrialkoxysilane.

[0050] More preferably, the silane coupling agent in step S2 is at least one of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane.

[0051] Preferably, the reaction temperature in step S2 is 40–70°C.

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] (1) The low carbon value halogen-free flame-retardant polypropylene composite material of the present invention incorporates organosilicon-modified phytic acid piperazine compounds as a halogen-free flame retardant to provide excellent flame retardant performance. Furthermore, the organosilicon-modified phytic acid piperazine compound flame retardant has good microscopic compatibility with polypropylene and bio-based polyethylene. The soft and hard segment phase structure of the rigid toughening particles of bio-based polyethylene is conducive to the compatibility of organosilicon-modified phytic acid piperazine compound molecules in it, and the intermolecular bonding is very tight, so that the prepared halogen-free flame-retardant polypropylene composite material achieves the effect of having excellent flame retardant performance, high modulus and high toughness mechanical properties, and low carbon value.

[0054] (2) The low-carbon halogen-free flame-retardant polypropylene composite material of the present invention can achieve V0 flame retardant effect, has high modulus and high toughness mechanical properties, outstanding balance of rigidity and toughness, and the GWP carbon value of the composite material is significantly reduced, making it particularly suitable for injection molding of low-carbon and environmentally friendly large interior and exterior automotive parts. Detailed Implementation

[0055] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0056] The relevant raw material information for the embodiments and comparative examples of the present invention is as follows (raw material information is provided by various suppliers):

[0057] Copolymer polypropylene:

[0058] Copolymer polypropylene-1: PPBX3900, under test standard ISO1133-2016, test conditions 230℃, 2.16Kg, melt flow rate is 60g / 10min, SK Korea, raw material carbon value GWP is 2260kg CO2 e / t;

[0059] Copolymer polypropylene-2: PPBX3500, under the test standard ISO1133-2016, test conditions of 230℃ and 2.16Kg, the melt flow rate is 10g / 10min, SK Korea, raw material carbon value GWP is 2290kg CO2 e / t;

[0060] Copolymer polypropylene-3: PPBX3920, under the test standard ISO1133-2016, test conditions of 230℃ and 2.16Kg, has a melt flow rate of 90g / 10min, from SK Korea, and the raw material carbon value GWP is 2320kg CO2 e / t;

[0061] Flame retardant:

[0062] Organosilicon-modified phytic acid piperazine compound-1 (VsPhypi-1), self-made, with a raw material carbon value GWP of 320 kg CO2e / t;

[0063] Organosilicon-modified phytic acid piperazine compound-2 (VsPhypi-2), self-made, with a raw material carbon value GWP of 340 kg CO2e / t;

[0064] Organosilicon-modified phytic acid piperazine compound-3 (VsPhypi-3), self-made, with a raw material carbon value GWP of 350 kg CO2e / t;

[0065] Halogen-free flame retardant-1: piperazine pyrophosphate, FP-2200, Adico, raw material carbon value GWP is 7200kg CO2 e / t;

[0066] Halogen-free flame retardant-2: Bisphenol A bis(diphenyl phosphate) BDP, Shandong Xurui New Material Co., Ltd., raw material carbon value GWP is 7600kg CO2 e / t;

[0067] Bio-based polyethylene:

[0068] Bio-based HDPE-1: SHA7260, Braskem, MFR: 20g / 10min, raw material GWP carbon value -2120kg CO2e / t;

[0069] Bio-based HDPE-2: SGE7252NS, Braskem, MFR: 2g / 10min, raw material GWP carbon value -2150kg CO2e / t;

[0070] Bio-based HDPE-3: SHC7260, Braskem, MFR: 7.2g / 10min, raw material GWP carbon value -2130kgCO2 e / t;

[0071] Bio-based LDPE-1: SPB608, Braskem, MFR: 30g / 10min, raw material GWP carbon value -2270kg CO2e / t;

[0072] Bio-based LDPE-2: SEB853, Braskem, MFR: 2.7g / 10min, raw material GWP carbon value -2300kg CO2e / t;

[0073] Petroleum-based HDPE: HDPE JV060U, Braskem, MFR: 7g / 10min, raw material GWP carbon value 1790kg CO2e / t;

[0074] Petroleum-based LDPE: Lupolen 2426H, Basell, MFR: 1.9 g / 10 min, raw material GWP carbon value 1800 kg CO2 e / t;

[0075] The above MFR measurements were all performed in accordance with ISO 1133-2016, under test conditions 1: 190℃ and 2.16kg.

[0076] Inorganic packing:

[0077] Talc powder: TYT-777A, commercially available, raw material carbon value GWP is 290kg CO2 e / t; Antioxidant 1010: commercially available, raw material carbon value GWP is 3200kg CO2 e / t;

[0078] Antioxidant 168: Commercially available, raw material carbon value GWP is 3400 kg CO2 e / t;

[0079] Weather resistant agent: LA-402AF: commercially available, raw material carbon value GWP is 2800kg CO2 e / t;

[0080] Lubricant: TR451: Commercially available, raw material carbon value GWP is 1700kg CO2 e / t.

[0081] The carbon value of talc and additives such as antioxidants, weathering agents, and lubricants comes from the manufacturing and transportation process.

[0082] Unless otherwise specified, all components used in the parallel embodiments and comparative examples are the same commercially available products.

[0083] Example 1

[0084] An organosilicon-modified phytic acid piperazine compound was prepared by the following steps:

[0085] S1. Dissolve a phytic acid solution with a phytic acid content of 0.05 mol in 200 ml of distilled water, then add 0.05 mol of piperazine to the above phytic acid aqueous solution. After the piperazine is completely dissolved, stir the resulting solution and react for 30 min to obtain a phytic acid-piperazine solution.

[0086] S2. In step S1, 0.025 mol of the silane coupling agent vinyltriethoxysilane (VTES) (soluble in 10 ml of ethanol) is added to the phytic acid piperazine solution. The mixture is stirred sequentially at room temperature for 6 h, at 40 °C for 1 h, at 50 °C for 1 h, at 60 °C for 1 h, and at 70 °C for 4 h. The clear solution is then transferred to a single-necked flask and evaporated at 95 °C for 4 h using a rotary evaporator. After removing the water, the solution is washed with ethanol and finally dried at 90 °C in a vacuum oven to constant weight. The final product is organosilicon-modified phytic acid piperazine compound-1 (VsPhypi-1), with a carbon value (GWP) of 320 kg CO2 e / t.

[0087] Example 2

[0088] This embodiment provides an organosilicon-modified phytic acid piperazine compound, the preparation process of which is basically the same as that of Example 1, except that: the molar amount of silane coupling agent added in step S2 is 0.05 mol, and the carbon value GWP of the prepared organosilicon-modified phytic acid piperazine compound-2 (VsPhypi-2) is 340 kg CO2 e / t.

[0089] Example 3

[0090] This embodiment provides an organosilicon-modified phytic acid piperazine compound, the preparation process of which is basically the same as that in Example 1, except that the silane coupling agent in step S2 is replaced with vinyltris(β-methoxyethoxy)silane, and the carbon value GWP of the prepared organosilicon-modified phytic acid piperazine compound-3 (VsPhypi-3) is 350 kg CO2 e / t.

[0091] Example 4

[0092] A low-carbon, halogen-free, flame-retardant polypropylene composite material, the weight parts of the raw materials used are shown in Table 1.

[0093] The preparation method of the above-mentioned low-carbon value halogen-free flame-retardant polypropylene composite material includes the following steps:

[0094] According to the weight parts in Table 1, polypropylene, organosilicon-modified phytic acid piperazine compound, halogen-free flame retardant, bio-based polyethylene, talc, antioxidant, weathering agent and lubricant are mixed evenly in a high-speed mixer, and then added to a twin-screw extruder with a length-to-diameter ratio of 40:1. The mixture is melt-blended at a temperature of 200°C, and then granulated, cooled and dried to obtain a polypropylene composition.

[0095] Examples 5 to 17

[0096] The weight proportions of the raw materials used in Examples 5 to 17 are shown in Table 1.

[0097] The preparation steps of Examples 5 to 17 are the same as those of Example 4.

[0098] Table 1 Formulation components of Examples 4 to 17

[0099]

[0100]

[0101] Continued from Table 1

[0102] Example 11 12 13 14 15 16 17 Copolymer Polypropylene-1 45 55 48 48 48 55 23 VsPhypi-1 20 20 20 / / 18 30 VsPhypi-2 / / / 20 / / / VsPhypi-3 / / / / 20 / / Bio-based HDPE-1 5 3 5 5 5 5 5 Bio-based LDPE-1 15 7 12 12 12 12 12 Inorganic packing 15 15 15 15 15 10 30 Antioxidant 1010 0.2 0.2 / 0.2 0.2 0.2 0.2 Antioxidant 168 0.2 0.2 / 0.2 0.2 0.2 0.2 Weathering agent 0.2 0.2 / 0.2 0.2 0.2 0.2 lubricant 0.1 0.1 / 0.1 0.1 0.2 0.2

[0103] Table 2 Formulation components of Comparative Examples 1 to 6

[0104]

[0105]

[0106] Performance testing

[0107] The properties of the polypropylene composite materials obtained in the above embodiments and comparative examples were characterized. The specific test items, test methods, and results are as follows:

[0108] (1) Mechanical property test: The prepared polypropylene composite material was injection molded under the conditions of injection temperature of 200℃, injection pressure of 45MPa, injection speed of 45S, holding pressure of 30MPa and holding time of 5S to obtain ISO standard flexural modulus and cantilever beam notched impact specimens. The flexural modulus (ISO178-2019) and cantilever beam notched impact strength (ISO180-2019) were tested using a universal mechanical testing machine and an impact testing machine, respectively. The notch was a type A notch.

[0109] (2) Flame retardant performance test: The prepared polypropylene composite material was injection molded under the conditions of injection temperature of 200℃, injection pressure of 45MPa, injection speed of 45S, holding pressure of 30MPa and holding time of 5S to obtain burning test strips. The test strips were 130mm×13mm×3.2mm in size. The samples were subjected to vertical burning test using a CZF-4 horizontal burner. The test standard was in accordance with GB / T2408-2008.

[0110] (3) Carbon Value (GWP): The carbon value of the polypropylene composites prepared in the examples and comparative examples was calculated with reference to ISO 14067:2018(E) standard "Greenhouse gases - Carbon footprint of products - Requirements and guidance for quantification and communication" and PAS 2050:2011 "Specifications for assessment of greenhouse gas emissions of goods and services over their life cycle". The databases were sourced from GaBi10 / GaBi10.6 database and Ecoinvent3.8 database.

[0111] Table 3 Performance test results of Examples 4 to 17 and Comparative Examples 1 to 6

[0112]

[0113]

[0114] The performance test results of the low-carbon-value halogen-free flame-retardant polypropylene composite materials of the various embodiments in Table 3 above show that the low-carbon-value halogen-free flame-retardant polypropylene composite materials of the present invention have excellent flame-retardant properties, all of which can achieve V0 flame-retardant effect. At the same time, they have high modulus and high toughness mechanical properties, with a flexural modulus of 2010-2400 MPa and a cantilever beam notched impact strength of 20-30 KJ / m. 2 It exhibits a superior balance of rigidity and toughness. Furthermore, the low-carbon, halogen-free flame-retardant polypropylene composite material of this invention has a significantly lower carbon value under the same filler and processing aid addition amounts. Within the addition range exemplified in the embodiments, the GWP carbon value is ≤1320kg CO2e / t, making it particularly suitable for injection molding of interior and exterior trim parts for environmentally friendly, low-carbon new energy vehicles.

[0115] In Comparative Examples 1 and 2, other halogen-free flame retardants, such as piperazine pyrophosphate and BDP, which are non-organosilicon-modified phytic acid piperazine compounds, were used. These halogen-free flame retardants could not achieve good microscopic compatibility and good flame retardant effect with polypropylene and bio-based polyethylene. The flame retardancy did not reach the V0 level, and the mechanical properties of the polypropylene composite material, especially the flexural modulus and notched impact performance, were significantly reduced. It did not have good mechanical properties with a good balance of rigidity and toughness. In addition, the GWP carbon value was ≥2500kg CO2 e / t, which was quite environmentally unfriendly.

[0116] In Comparative Examples 3 and 4, bio-based polyethylene and petroleum-based polyethylene were used as a blend. The mechanical properties of the polypropylene composite material were lower than those in the examples, and the GWP carbon value was higher, which could not achieve the technical effect of the present invention.

[0117] The ratio of bio-based HDPE to bio-based LDPE used in Comparative Examples 5 and 6 is not within the scope of protection of this invention. Although the GWP carbon value is low, the mechanical properties of the material are affected to a certain extent, and the technical effect of this invention cannot be achieved.

[0118] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-carbon, halogen-free, flame-retardant polypropylene composite material, characterized in that, Based on parts by weight, it comprises the following components: 20-60 parts of copolymerized polypropylene, 18-30 parts of organosilicon-modified phytic acid piperazine compound, 10-20 parts of bio-based polyethylene, and 10-30 parts of inorganic filler; The bio-based polyethylene includes bio-based high-density polyethylene and bio-based low-density polyethylene; The ratio of bio-based high-density polyethylene to bio-based low-density polyethylene in the bio-based polypropylene is 1:2 to 3.

2. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, The organosilicon-modified phytic acid piperazine compound has a mass percentage content of 15-35% in the low-carbon-value halogen-free flame-retardant polypropylene composite material.

3. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, The copolymer polypropylene exhibits a melt flow rate of 30-100 g / 10 min under test conditions of 230°C and 2.16 kg.

4. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, The bio-based high-density polyethylene exhibits a melt flow rate of 5–50 g / 10 min under test conditions of 190°C and 2.16 kg. The bio-based low-density polyethylene exhibits a melt flow rate of 5–50 g / 10 min under test conditions of 190°C and 2.16 kg.

5. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, The inorganic filler includes at least one of talc, calcium carbonate, wollastonite, and whiskers.

6. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, It also includes 0.05-5 parts by weight of processing aids.

7. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 1, characterized in that, The organosilicon-modified phytic acid piperazine compound is prepared by the following steps: S1. Add phytic acid solution and piperazine to water in sequence, and stir to react to obtain phytic acid-piperazine solution; S2. After adding a silane coupling agent to the phytate piperazine solution prepared in S1, the mixture is stirred and reacted. The solvent is evaporated, the mixture is washed, and dried to obtain the organosilicon-modified phytate piperazine compound.

8. The low-carbon, halogen-free, flame-retardant polypropylene composite material according to claim 7, characterized in that, The molar ratio of phytic acid to piperazine added in step S1 is 1 to 2:1; the molar ratio of phytic acid-piperazine to silane coupling agent in step S2 is 1 to 2:

1.

9. A method for preparing the low-carbon halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing all components evenly, adding them to an extruder, melting and kneading them, then granulating, cooling, and drying to obtain the low-carbon halogen-free flame-retardant polypropylene composite material.

10. The application of the low-carbon halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 6 in the preparation of automotive interior parts.

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