Polypropylene composite material, and preparation method and application thereof

Abstract

The application discloses a polypropylene composite material and a preparation method and application thereof, and relates to the technical field of polymer composite materials.The polypropylene composite material comprises the following components in parts by mass: 70-80 parts of polypropylene; 0.3-0.8 parts of an antioxidant; 1-5 parts of a hypophosphite flame retardant; 0.2-0.6 parts of a bromine-based flame retardant; 5-16 parts of talcum powder loaded with a flame-retardant synergist; and 5-11 parts of a processing aid; and the antioxidant contains greater than or equal to 10% of a benzofuranone antioxidant in terms of mass percentage.The polypropylene composite material obtained by the application is a low-halogen flame-retardant polypropylene material, and the stable melt index and melt strength can be ensured during high-temperature processing, so that the stable extrusion of thick plates is ensured, and the polypropylene composite material is suitable for the preparation of thick plate extrusion products with a thickness of 10 mm or more.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a polypropylene composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) boasts advantages such as abundant supply, light weight, good electrical insulation, good chemical resistance, excellent mechanical and heat resistance properties, and low cost, making it widely used in various fields of daily life, including automobiles, home appliances, construction, agriculture, medicine and health, and food packaging. However, PP itself is a flammable material, easily combustible and capable of causing fires, posing a safety hazard and significantly limiting its application range. Adding flame retardants to improve the flame-retardant properties of PP is an effective way to expand its application scope.

[0003] Currently, UL94 V-2 flame-retardant polypropylene on the market is mainly divided into two categories: one is halogenated flame-retardant polypropylene prepared with bromine-antimony compound flame retardants, which has the advantages of high flame retardant efficiency and good flame retardant stability, but its high halogen content will produce a large amount of dense smoke and toxic gases when burning, thus having an adverse effect on human health and the environment; the other is low-halogenated flame-retardant polypropylene prepared with phosphorus, nitrogen and bromine compound flame retardants, which has the characteristics of low halogen, low smoke and low toxicity. At the same time, because the unit cost of the flame retardant is low and the addition ratio is low, this type of flame-retardant polypropylene has a high cost performance.

[0004] Low-halogen flame-retardant polypropylene (PHPP) has been widely used in various injection molding processes and some extrusion processes, such as extruded films, sheets, and pipes. Compared with injection molding, extrusion requires relatively higher melt strength, especially for thicker products (e.g., over 10 mm thick). However, low-halogen flame-retardant polypropylene contains free radical initiators such as polyhydroxyl or polyhydroxyl, which makes it prone to degradation during processing. This leads to an increase in melt index and a decrease in melt strength, limiting its application in thick sheet extrusion. Existing low-halogen flame-retardant polypropylene materials are difficult to make suitable for both low-halogen flame retardancy and thick sheet extrusion. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a polypropylene composite material that, by adding specific antioxidants, enhances the antioxidants' ability to capture free radicals under high-temperature processing conditions, inhibits resin degradation, and stabilizes the melt index and melt strength while ensuring low-halogen flame retardancy, thereby satisfying the stability requirements of the thick plate extrusion process.

[0006] A second aspect of the present invention is to provide a method for preparing a polypropylene composite material.

[0007] A third aspect of the present invention is to provide a thick plate component.

[0008] A fourth aspect of the present invention is to provide a method for preparing a thick plate part.

[0009] A fifth aspect of the present invention is to provide an application of a polypropylene composite material or a thick plate component.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A first aspect of the present invention provides a polypropylene composite material comprising the following components in parts by mass:

[0012] 70-80 parts polypropylene; 0.3-0.8 parts antioxidant; 1-5 parts hypophosphite flame retardant; 0.2-0.6 parts brominated flame retardant; 5-16 parts talc loaded with flame retardant synergist; 5-11 parts processing aid;

[0013] The antioxidant contains ≥10% by mass of benzofuranone antioxidants.

[0014] The polypropylene composite material provided by this invention contains a certain amount of benzofuranone antioxidants in the selected antioxidant combination. These antioxidants enhance the material's ability to capture free radicals under high-temperature processing conditions, thereby significantly inhibiting resin degradation and stabilizing the melt index and melt strength of the polypropylene composite material. This ensures the material has a low melt index and sufficient melt strength, improving the stability of the thick-plate extrusion process. Furthermore, the talc powder in the formulation of this invention serves as a carrier for the flame retardant synergist, forming talc powder loaded with the flame retardant synergist within the polypropylene composite material. The flame retardant synergist contains a free radical initiator. With the carrier effect of the talc powder, the chemical reaction time between the free radical initiator and the resin can be reduced, weakening the degradation tendency of the polypropylene composite material during processing.

[0015] In some embodiments of the present invention, the antioxidant contains 10-20% by mass of a benzofuranone antioxidant.

[0016] In some embodiments of the present invention, the antioxidant contains 16-20% by mass of a benzofuranone antioxidant.

[0017] In some embodiments of the present invention, the antioxidant includes benzofuranone antioxidants, as well as at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0018] In some embodiments of the present invention, the benzofuranone antioxidants include antioxidant HP-136 and / or antioxidant Revonox 501.

[0019] In some embodiments of the present invention, the hindered phenolic antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1098.

[0020] In some embodiments of the present invention, the phosphite antioxidant includes at least one of antioxidant 168 and antioxidant 626.

[0021] In some embodiments of the present invention, the SiO2 content in the talc powder is ≥58% by mass.

[0022] In some embodiments of the present invention, the SiO2 content in the talc powder is 58-61% by mass.

[0023] In some specific embodiments of the present invention, the SiO2 content in the talc powder is 58-60% by mass.

[0024] In some embodiments of the present invention, the talc powder has a mesh size of 4000 to 6000 mesh.

[0025] In some embodiments of the present invention, the talc powder has a mesh size of 4500 to 5500 mesh.

[0026] In some embodiments of the present invention, the melt index of the polypropylene at 230°C and 2.16 kg load is 0.2 to 0.5 g / 10 min.

[0027] In some embodiments of the present invention, the melt index of the polypropylene at 230°C and 2.16 kg load is 0.2 to 0.4 g / 10 min.

[0028] In some embodiments of the present invention, the polypropylene is a block copolymer polypropylene.

[0029] In some embodiments of the present invention, the processing aid includes 4.7 to 10 parts of toughening agent and 0.3 to 1 part of lubricant.

[0030] In some embodiments of the present invention, the talc powder loaded with the flame retardant synergist comprises 0.2 to 1 part of the flame retardant synergist and 4.8 to 15 parts of talc powder.

[0031] In some embodiments of the present invention, the talc powder loaded with the flame retardant synergist comprises 0.2 to 0.6 parts of the flame retardant synergist and 5 to 15 parts of talc powder.

[0032] In some specific embodiments of the present invention, the talc powder loaded with the flame retardant synergist comprises 0.4 to 0.6 parts of the flame retardant synergist and 8 to 12 parts of the talc powder.

[0033] In some embodiments of the present invention, the mass ratio of talc to flame retardant synergist is 1:(0.02-0.08).

[0034] In some specific embodiments of the present invention, the mass ratio of talc powder to flame retardant synergist is 1:(0.04-0.06).

[0035] In some embodiments of the present invention, the lubricant includes at least one of erucamide, oleamide, stearic acid, magnesium stearate, calcium stearate, zinc stearate, silicone powder, paraffin wax, polyethylene wax, and ethylene bis-stearamide.

[0036] In some embodiments of the present invention, the toughening agent includes at least one of ethylene-octene copolymer (POE), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), and ethylene propylene diene monomer (EPDM).

[0037] In some embodiments of the present invention, the polypropylene composite material comprises the following components in parts by mass:

[0038] 70-80 parts polypropylene; 0.3-0.8 parts antioxidant; 1-5 parts hypophosphite flame retardant; 0.2-0.6 parts bromine-based flame retardant; 0.2-0.6 parts flame retardant synergist; 5-15 parts talc; 5-10 parts toughening agent; 0.3-0.8 parts lubricant.

[0039] In some embodiments of the present invention, the polypropylene composite material comprises the following components in parts by mass:

[0040] Polypropylene 75-79 parts; antioxidant 0.4-0.5 parts; hypophosphite flame retardant 3-5 parts; bromine flame retardant 0.4-0.6 parts; flame retardant synergist 0.4-0.6 parts; talc 8-12 parts; toughening agent 5-10 parts; lubricant 0.3-0.8 parts.

[0041] In some embodiments of the present invention, the hypophosphite flame retardant includes at least one of aluminum hypophosphite, calcium hypophosphite, and magnesium hypophosphite.

[0042] In some embodiments of the present invention, the brominated flame retardant includes at least one of octabromoether, octabromobisphenol S ether, decabromodiphenyl ethane, and melamine hydrobromide.

[0043] In some embodiments of the present invention, the flame retardant synergist includes at least one of tantalizer and polytantalizer.

[0044] Both lysophosphatidylcholine and polylysophosphatidylcholine are free radical initiators.

[0045] A second aspect of the present invention provides a method for preparing the polypropylene composite material described in the first aspect of the present invention, comprising the following steps:

[0046] Polypropylene, antioxidant, hypophosphite flame retardant, brominated flame retardant, and processing aid are blended and fed into an extruder through the main feed port. Talc and flame retardant synergist are blended and fed into the extruder through the side feed port. The polypropylene composite material is then extruded. The extrusion temperature is 170-180℃.

[0047] In the preparation of polypropylene composite materials, this invention uses talc powder as a carrier, fed together with a flame retardant synergist through a side feed port. This reduces the chemical reaction time between the free radical initiator in the flame retardant synergist and the resin. Simultaneously, employing a lower base temperature reduces the temperature-induced degradation-promoting effect, thereby lowering the degradation trend of the polypropylene composite material during extrusion, ensuring the melt index and melt strength of the polypropylene composite material, and improving extrusion stability. Under such extrusion temperature conditions of 170–180°C, the stability of the molded material can be guaranteed.

[0048] Talc powder and flame retardant synergist are blended and fed into the extruder through the side feed port, and finally exist as talc powder loaded with flame retardant synergist in polypropylene composite material.

[0049] In some embodiments of the present invention, the mixing speed of the blend is 800-1000 r / min.

[0050] In some embodiments of the present invention, the mixing time for the blending is 3 to 5 minutes.

[0051] In some embodiments of the present invention, the blending is carried out in a high-speed mixer.

[0052] In some embodiments of the present invention, the extruder is a twin-screw extruder.

[0053] In some embodiments of the present invention, the length-to-diameter ratio of the extruder is (40-50):1.

[0054] In some embodiments of the present invention, the extrusion temperature is 170–175°C.

[0055] In some embodiments of the present invention, the screw speed of the extruder is 400 to 450 r / min.

[0056] In some embodiments of the present invention, the vacuum degree of the extruder is >0.08MPa.

[0057] A third aspect of the present invention provides a thick plate component, the raw material for which the preparation includes the polypropylene composite material described in the first aspect of the present invention; the thickness of the thick plate component is ≥10mm.

[0058] The polypropylene composite material obtained by this invention is a low-halogen flame-retardant polypropylene material. During high-temperature processing, it can keep the melt index and melt strength stable within the range that meets the requirements of thick plate extrusion, ensuring the stable progress of thick plate extrusion. It is suitable for preparing thick plate extrusion products with a thickness of 10 mm and above.

[0059] In some embodiments of the present invention, the thickness of the thick plate component is 10 to 14 mm.

[0060] In some embodiments of the present invention, the thickness of the thick plate component is 11.5 to 13.5 mm.

[0061] A fourth aspect of the present invention provides a method for preparing the thick plate part described in the third aspect of the present invention, comprising the following steps:

[0062] The polypropylene composite material is extruded at 170-180°C and molded to obtain a thick plate part.

[0063] The fifth aspect of the present invention provides an application of the polypropylene composite material described in the first aspect of the present invention or the thick plate part described in the third aspect of the present invention in the fields of automobiles, home appliances, construction or agriculture.

[0064] Compared with the prior art, the present invention has at least the following beneficial effects:

[0065] (1) The antioxidant in the polypropylene composite material provided by this invention contains a certain amount of benzofuranone antioxidants, which have a high ability to capture free radicals under high-temperature processing conditions, and can significantly inhibit resin degradation, thereby stabilizing the melt index and melt strength of the polypropylene composite material, reducing the melt index and ensuring sufficient melt strength, and improving the stability of thick plate extrusion; the formulation contains talc powder loaded with flame retardant synergists. Talc powder acts as a carrier for flame retardant synergists. With the help of the carrier effect of talc powder, the chemical reaction time between the free radical initiator and the resin can be reduced, and the degradation tendency of the polypropylene composite material during processing can be weakened. Therefore, the polypropylene composite material of this invention not only has low-halogen flame retardant properties, but is also suitable for thick plate extrusion processing.

[0066] (2) This invention further specifies that the polypropylene in the polypropylene composite material is block copolymer polypropylene, with a melt index of 0.2 to 0.5 g / 10 min at test conditions of 230℃ / 2.16 kg. It has high melt strength and is very suitable as a raw material for preparing materials suitable for thick plate extrusion. In addition, this invention further specifies the toughening agent in the processing aid, which can further improve the melt strength of the material, thereby ensuring the stability of thick plate extrusion.

[0067] (3) In the process of preparing polypropylene composite material, the present invention uses talc powder as a carrier and feeds it together with flame retardant synergist through the side feed port. This can reduce the chemical reaction time between the free radical initiator contained in the flame retardant synergist and the resin. At the same time, the use of a lower base temperature can reduce the promoting effect of temperature on degradation, thereby reducing the degradation trend of polypropylene composite material in the extrusion process, stabilizing the melt index and melt strength of polypropylene composite material, and ensuring the stability of extrusion.

[0068] (4) The polypropylene composite material obtained by the present invention is a low-halogen flame-retardant polypropylene material. It can stabilize the melt index and melt strength during high-temperature processing, ensuring the stable extrusion of thick plates. It is suitable for preparing thick plate extrusion products with a thickness of 10 mm or more. The obtained products can be applied in the fields of automobiles, home appliances, construction or agriculture. Detailed Implementation

[0069] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0070] The following describes some of the raw materials used in the following embodiments and comparative examples of the present invention:

[0071] Polypropylene: B1600 (MI is 0.3 g / 10 min), Guangzhou Petrochemical.

[0072] Polypropylene: EP300M (MI is 9g / 10min), CNOOC Shell.

[0073] Toughening agent: SEBS, YH-501T, Yueyang Petrochemical.

[0074] Inorganic hypophosphite flame retardant: aluminum hypophosphite, commercially available; the same type is used in the following examples and comparative examples of this invention.

[0075] Bromine-based flame retardant: melamine hydrobromide, commercially available; the same is used in the following examples and comparative examples of this invention.

[0076] Flame retardant synergist: Polymerized thiocyanate, commercially available; the same is used in the following examples and comparative examples of this invention.

[0077] Lubricant: EBS P130, CMS Indonesia.

[0078] Antioxidants: 1010, 168, HP-136, BASF; Revonox 501, Chitai Technology.

[0079] Talc powder A: 5000 mesh, SiO2 content 60%, commercially available.

[0080] Talc powder B: 5000 mesh, SiO2 content 50%, commercially available.

[0081] In the embodiments and comparative examples of this invention, the melt flow index of polypropylene or polypropylene composite materials was measured at 230℃ / 2.16kg in accordance with GB / T3682.1-2018.

[0082] The following detailed description is provided in conjunction with embodiments and comparative examples:

[0083] Example 1

[0084] This embodiment provides a polypropylene composite material, the formulation of which is shown in Table 1 and the preparation parameters are shown in Table 2.

[0085] The preparation method of the polypropylene composite material in this embodiment includes the following steps:

[0086] Add 78.05 parts of polypropylene (B1600), 6 parts of toughening agent SEBS (YH-602T), 4 parts of aluminum hypophosphite, 0.5 parts of melamine hydrobromide, 0.5 parts of lubricant EBS (P130), 0.2 parts of antioxidant (1010), 0.2 parts of antioxidant (168), and 0.05 parts of antioxidant (HP-136) to a high-speed mixer, adjust the mixer speed to 800 r / min, mix for 3 min, and then transfer the material in the high-speed mixer to the main feed port of a twin-screw extruder;

[0087] Add 10 parts of talc powder A and 0.5 parts of polymethyl methacrylate to a high-speed mixer and mix. Adjust the mixer speed to 800 r / min and mix for 3 minutes. Then transfer the material in the high-speed mixer to the side feed port of the twin-screw extruder.

[0088] Start the twin-screw extruder, control the extrusion temperature at 170-175℃, the screw speed at 400 r / min, and the vacuum degree at >0.08 MPa. After extrusion and granulation, a polypropylene composite material is obtained.

[0089] Example 2

[0090] This embodiment provides a polypropylene composite material, the formulation of which is shown in Table 1 and the preparation parameters are shown in Table 2.

[0091] The preparation method of the polypropylene composite material in this embodiment includes the following steps:

[0092] Add 75.05 parts polypropylene (B1600), 9 parts toughening agent SEBS (YH-602T), 4 parts aluminum hypophosphite, 0.5 parts melamine hydrobromide, 0.5 parts lubricant EBS (P130), 0.2 parts antioxidant (1010), 0.2 parts antioxidant (168), and 0.05 parts antioxidant (HP-136) to a high-speed mixer, adjust the mixer speed to 800 r / min, mix for 3 min, and then transfer the material in the high-speed mixer to the main feed port of a twin-screw extruder;

[0093] Add 10 parts of talc powder A and 0.5 parts of polymethyl methacrylate to a high-speed mixer and mix. Adjust the mixer speed to 800 r / min and mix for 3 minutes. Then transfer the material in the high-speed mixer to the side feed port of the twin-screw extruder.

[0094] Start the twin-screw extruder, control the extrusion temperature at 170-175℃, the screw speed at 400 r / min, and the vacuum degree at >0.08 MPa. After extrusion and granulation, a polypropylene composite material is obtained.

[0095] Example 3

[0096] This embodiment provides a polypropylene composite material, the formulation of which is shown in Table 1 and the preparation parameters are shown in Table 2.

[0097] The preparation method of the polypropylene composite material in this embodiment includes the following steps:

[0098] Add 78 parts polypropylene (B1600), 6 parts toughening agent SEBS (YH-602T), 4 parts aluminum hypophosphite, 0.5 parts melamine hydrobromide, 0.5 parts lubricant EBS (P130), 0.2 parts antioxidant (1010), 0.2 parts antioxidant (168), and 0.1 parts antioxidant (HP-136) to a high-speed mixer, adjust the mixer speed to 800 r / min, mix for 3 minutes, and then transfer the material in the high-speed mixer to the main feed port of a twin-screw extruder.

[0099] Add 10 parts of talc powder A and 0.5 parts of polymethyl methacrylate to a high-speed mixer and mix. Adjust the mixer speed to 800 r / min and mix for 3 minutes. Then transfer the material in the high-speed mixer to the side feed port of the twin-screw extruder.

[0100] Start the twin-screw extruder, control the extrusion temperature at 170-175℃, the screw speed at 400 r / min, and the vacuum degree at >0.08 MPa. After extrusion and granulation, a polypropylene composite material is obtained.

[0101] Example 4

[0102] This embodiment provides a polypropylene composite material, the formulation of which is shown in Table 1 and the preparation parameters are shown in Table 2.

[0103] The preparation method of the polypropylene composite material in this embodiment includes the following steps:

[0104] Add 78.05 parts polypropylene (B1600), 6 parts toughening agent SEBS (YH-602T), 4 parts aluminum hypophosphite, 0.5 parts melamine hydrobromide, 0.5 parts lubricant EBS (P130), 0.2 parts antioxidant (1010), 0.2 parts antioxidant (168), and 0.05 parts antioxidant (Revonox 501) to a high-speed mixer, adjust the mixer speed to 800 r / min, mix for 3 min, and then transfer the material in the high-speed mixer to the main feed port of a twin-screw extruder.

[0105] Add 10 parts of talc powder A and 0.5 parts of polymethyl methacrylate to a high-speed mixer and mix. Adjust the mixer speed to 800 r / min and mix for 3 minutes. Then transfer the material in the high-speed mixer to the side feed port of the twin-screw extruder.

[0106] Start the twin-screw extruder, control the extrusion temperature at 170-175℃, the screw speed at 400 r / min, and the vacuum degree at >0.08 MPa. After extrusion and granulation, a polypropylene composite material is obtained.

[0107] Example 5

[0108] This embodiment provides a polypropylene composite material, which differs from Example 1 in that the polypropylene is replaced with EP300M, and the rest is the same as in Example 1; the specific formula is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0109] Example 6

[0110] This embodiment provides a polypropylene composite material, which differs from Example 1 in that: talc powder B (SiO2 mass content 50%) is used to replace talc powder A (SiO2 mass content 60%) in an equal amount, while the rest is the same as in Example 1; the specific formula is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0111] Comparative Example 1

[0112] This comparative example provides a polypropylene composite material, which differs from Example 1 in that: no antioxidant (HP-136) was added, but the total amount of antioxidant remained unchanged, and the rest was the same as in Example 1; the specific formulation is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0113] Comparative Example 2

[0114] This comparative example provides a polypropylene composite material, which differs from Example 1 in that: the toughening agent SEBS (YH-602T) was not added, the polypropylene B1600 was 84.05 parts, and the rest were the same as in Example 1; the specific formulation is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0115] Comparative Example 3

[0116] This comparative example provides a polypropylene composite material, which differs from Example 1 in that the extrusion temperature is set to 190-200℃, while the rest is the same as in Example 1; the specific formulation is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0117] Comparative Example 4

[0118] This comparative example provides a polypropylene composite material, which differs from Example 1 in that: talc and polymethyl ether are mixed with other components in the formulation using a high-speed mixer and then added through the main feed inlet; the rest is the same as in Example 1; the specific formulation is shown in Table 1, the preparation method is the same as in Example 1, and the preparation parameters are shown in Table 2.

[0119] The formulations of the polypropylene composite materials for the examples and comparative examples are shown in Table 1 below:

[0120] Table 1. Formulation of polypropylene composite materials for examples and comparative examples.

[0121]

[0122]

[0123] It should be noted that talc powder and flame retardant synergist form talc powder loaded with flame retardant synergist.

[0124] The extrusion processing temperature and feeding method of the polypropylene composite materials in the examples and comparative examples are shown in Table 2 below:

[0125] Table 2. Extrusion processing temperature and feeding method of polypropylene composite materials in the examples and comparative examples.

[0126] Extrusion temperature (°C) Feeding method Example 1 170～175 Main feeding + side feeding Example 2 170～175 Main feeding + side feeding Example 3 170～175 Main feeding + side feeding Example 4 170～175 Main feeding + side feeding Example 5 170～175 Main feeding + side feeding Example 6 170～175 Main feeding + side feeding Comparative Example 1 170～175 Main feeding + side feeding Comparative Example 2 170～175 Main feeding + side feeding Comparative Example 3 190～200 Main feeding + side feeding Comparative Example 4 170～175 Full-feeding

[0127] Result detection

[0128] The following performance tests were performed on the polypropylene composite materials of the examples and comparative examples:

[0129] Flame retardant performance: tested according to UL-94 testing standards;

[0130] Thick plate extrusion test: The test is conducted by extruding thick plates on site. The main process is as follows: First, the polypropylene composite material is extruded, shaped by two rollers, and cooled to form a plate of fixed thickness. The extrusion temperature is 170-180℃, the die temperature is 180℃, the double roller temperature is 90℃, and the final extruded thick plate thickness is 12±0.2mm.

[0131] The test results are shown in Table 3 below.

[0132] Table 3. Performance test results of polypropylene composite materials in the examples and comparative examples.

[0133]

[0134]

[0135] In addition, the polypropylene composite material V-2 obtained in Example 5 was qualified, but the melt index was high and the thick plate extrusion effect was poor. The flame retardant effect of the polypropylene composite material obtained in Example 6 was worse than that of Examples 1 to 5, but its melt index was 0.6 g / 10 min. In the thick plate extrusion test, it was still able to maintain extrusion stability, uniform thickness and smooth surface.

[0136] As shown in Table 3, the thick plate extrusion test results demonstrate that the present invention effectively ensures the stability of the thick plate extrusion process and achieves good extrusion processing by selecting appropriate antioxidants in the polypropylene resin system, controlling the extrusion temperature appropriately, and adopting a main-feed + side-feed method. The stability of thick plate extrusion is related to the stability of the material's melt index. In all embodiments of the present invention, the melt index did not exceed 0.8 g / 10 min, resulting in sufficient and stable melt strength for the polypropylene composite material. This is beneficial for the uniformity of the material discharge rate, thereby ensuring the stability of the thick plate extrusion. On the other hand, the addition of toughening agents also affects the stability of thick plate extrusion. The addition of toughening agents further improves the melt strength of the material, ensuring the stability of the extrusion.

[0137] As can be seen from Examples 1-4 of this invention, the addition of benzofuranone antioxidant HP-136 / Revonox 501 to the hindered phenolic antioxidant 1010 and phosphite antioxidant 168 can effectively inhibit the degradation of polypropylene composites during extrusion granulation or thick plate extrusion. Furthermore, comparing Examples 1 and 3, it can be seen that different amounts of HP-136 result in different melt flow indices of the polypropylene composites, indicating different degrees of degradation inhibition and improvements in the stability of thick plate extrusion. This is because carbon free radicals are the source of peroxide and oxygen free radical formation during the extrusion process of polypropylene composites. HP-136 / Revonox 501 is a benzofuranone-type carbon free radical scavenger, and its α-H molecules readily react with carbon free radicals. By capturing carbon free radicals, it can effectively inhibit the degradation of polypropylene composites. Different amounts result in different α-H contents, thus affecting the degree of inhibition.

[0138] In terms of process, this invention utilizes talc as a carrier and designs the free radical initiator polycarboxylate to be fed in via a side-feed method, which can reduce the chemical reaction time between the free radical initiator and the resin. Furthermore, using a lower extrusion temperature can also reduce the temperature-induced degradation-promoting effect. Therefore, through these two aspects of process control, the degradation tendency of polypropylene composites during the extrusion granulation stage can be reduced, thereby further stabilizing the melt index and melt strength of the polypropylene composites and ensuring the stability of thick-plate extrusion.

[0139] Comparing the test results of Example 1 and Example 5, it can be seen that replacing the polypropylene resin with EP300M, which has a higher melt index, increases the melt index of the resulting polypropylene composite material, leading to a decrease in the melt strength of the polypropylene composite material and a decrease in the stability of thick plate extrusion.

[0140] Comparing the test results of Examples 1 and 6, it can be seen that although the stability and appearance of the thick sheet extrusion process remained normal after replacing talc powder A with talc powder B, which has a lower SiO2 content, the flame retardant effect of the polypropylene composite material deteriorated, failing to meet the UL94 V-2 standard. This is because talc powder with a lower SiO2 content corresponds to a higher content of calcium compounds. These calcium compounds are highly active, and the higher their content, the greater the negative impact on the flame retardant. Talc powder A selected in Example 1, with its lower calcium compound content, had a smaller negative impact on flame retardancy, thus ensuring the flame retardant performance of the polypropylene composite material.

[0141] Comparing the test results of Example 1 and Comparative Example 1, it can be seen that when HP-136 / Revonox 501 was not added to the formulation, even with the total amount of antioxidant remaining unchanged, the melt index of the resulting polypropylene composite material was significantly higher, indicating insufficient melt strength. This resulted in inconsistent extrusion speeds during thick plate extrusion, poor plate thickness uniformity, and thinner areas exhibiting rougher surfaces due to insufficient roller pressure. This suggests that the polycarboxylic acid in the formulation triggered degradation of the polypropylene composite material during extrusion processing, and that using only hindered phenol 1010 antioxidant combined with phosphite antioxidant 168 was insufficient to effectively inhibit material degradation.

[0142] Comparing the test results of Example 1 and Comparative Example 2, it can be seen that even with the presence of HP-136 antioxidant protecting the polypropylene composite material and inhibiting degradation, the melt index of the resulting polypropylene composite material is low when no toughening agent is added to the formulation and the polypropylene content is high. However, slight extrusion defects still occur during the thick plate extrusion process, indicating that the melt strength of the material is insufficient and is not conducive to the stability of the thick plate extrusion process.

[0143] Comparing the test results of Example 1 and Comparative Example 3, it can be seen that after raising the extrusion granulation temperature to 190-200℃, the melt index of the polypropylene composite material is significantly higher, and the stability of the extruded thick plate is reduced. This indicates that the higher extrusion temperature exacerbates the degradation of the material and reduces the extrusion stability of the thick plate.

[0144] Comparing the test results of Example 1 and Comparative Example 4, it can be seen that after changing the feeding process from a main feeding + side feeding process to a full main feeding process, the melt index of the polypropylene composite material is significantly higher than that of Example 1, and the stability of thick plate extrusion decreases. This is mainly because, with the full main feeding process, the chemical reaction time between the free radical initiator and the resin is relatively long, which exacerbates the degradation of the polypropylene composite material. Even with the protection of HP-136 antioxidant, the prepared polypropylene composite material cannot meet the requirements of thick plate extrusion processing.

[0145] In summary, the polypropylene composite material obtained by this invention is a low-halogen flame-retardant polypropylene material that can stabilize the melt index and melt strength during high-temperature processing, ensuring the stable extrusion of thick plates. It is suitable for preparing thick plate extrusion products with a thickness of 10 mm or more and can be used in the automotive, home appliance, construction, and agricultural fields.

[0146] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A polypropylene composite material, characterized in that, Includes the following components by parts by mass: 70-80 parts polypropylene; 0.3-0.8 parts antioxidant; 1-5 parts hypophosphite flame retardant; 0.2-0.6 parts brominated flame retardant; 5-16 parts talc loaded with flame retardant synergist; 5-11 parts processing aid; The antioxidant contains ≥10% by mass of benzofuranone antioxidants; The processing aids include 4.7 to 10 parts toughening agent and 0.3 to 1 part lubricant; The talc powder contains 58-61% SiO2 by mass. The polypropylene has a melt flow index of 0.2~0.5 g / 10 min at 230℃ and 2.16 kg load; The flame retardant synergist includes at least one of tannin and polytannin; The polypropylene composite material is prepared by a method comprising the following steps; Polypropylene, antioxidant, hypophosphite flame retardant, brominated flame retardant, and processing aid are blended and fed into an extruder through the main feed port. Talc and flame retardant synergist are blended and fed into the extruder through the side feed port. The polypropylene composite material is then extruded. The extrusion temperature is 170~180℃.

2. The polypropylene composite material according to claim 1, characterized in that, The antioxidant contains 10-20% by weight of benzofuranone antioxidants; And / or, the antioxidant further includes at least one of hindered phenolic antioxidants and phosphite antioxidants.

3. The polypropylene composite material according to claim 1, characterized in that, The talc powder has a mesh size of 4000~6000 mesh.

4. The polypropylene composite material according to claim 1, characterized in that, The talc powder loaded with the flame retardant synergist comprises 0.2 to 1 part of the flame retardant synergist and 4.8 to 15 parts of talc powder.

5. The polypropylene composite material according to claim 1, characterized in that, The hypophosphite flame retardant includes at least one of aluminum hypophosphite, calcium hypophosphite, and magnesium hypophosphite. And / or, the brominated flame retardant includes at least one of octabromoether, octabromobisphenol S ether, decabromodiphenyl ethane, and melamine hydrobromide.

6. A method for preparing the polypropylene composite material according to any one of claims 1 to 5, characterized in that, Includes the following steps: Polypropylene, antioxidant, hypophosphite flame retardant, brominated flame retardant, and processing aid are blended and fed into an extruder through the main feed port. Talc and flame retardant synergist are blended and fed into the extruder through the side feed port. The polypropylene composite material is then extruded. The extrusion temperature is 170~180℃.

7. A thick plate component, characterized in that, The raw materials for preparation include the polypropylene composite material according to any one of claims 1 to 5; the thickness of the thick plate part is ≥10mm.

8. A method for preparing a thick plate component as described in claim 7, characterized in that, The process includes the following steps: extruding the polypropylene composite material at 170~180℃ and molding it to obtain a thick plate part.

9. The application of a polypropylene composite material according to any one of claims 1 to 5 or a thick plate component according to claim 7 in the automotive, home appliance, construction or agricultural fields.

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