Polypropylene composite material, preparation method therefor, and use thereof

Abstract

The present application provides a polypropylene composite material, a preparation method therefor, and use thereof. The polypropylene composite material comprises a prepreg fabric and a first polypropylene layer laminated in sequence; in parts by weight, the first polypropylene layer comprises 15-60 parts of a first polypropylene resin, 15-25 parts of a first piperazine flame retardant, 5-15 parts of a first nitrogen-phosphorus composite flame retardant, 0.1-2 parts of a first synergistic flame retardant, and 5-30 parts of long glass fibers. In the present application, the polypropylene composite material has both good ablation resistance and low post-ablation deformation, and at the same time, the polypropylene composite material has a high flame retardancy rating and good falling ball impact resistance.

Description

Polypropylene composite material and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, for example, a polypropylene composite material and a preparation method and application thereof. BACKGROUND

[0002] With the vigorous development of the new energy industry, the installed capacity of power batteries and energy storage batteries is breaking new records, and the material of the battery pack upper cover, as one of the components of the power battery and the energy storage battery, is mainly metal or thermosetting material, which has the disadvantages of large specific gravity, low processing efficiency, and environmental pollution. With the continuous promotion of the national double carbon policy, thermoplastic materials have been rapidly popularized and applied due to their light specific gravity and green environmental protection advantages.

[0003] At present, polypropylene (PP) material is a commonly used thermoplastic material for battery pack upper covers. However, the core requirement of the battery pack is to pass the GB / T31467.3-2015 fire resistance test, and it is required that no large amount of toxic and harmful gases are generated during the combustion process. However, conventional PP cannot meet the existing requirements. Therefore, developing low-smoke, halogen-free, ablation-resistant, and heat-insulating flame-retardant enhanced PP to meet the test requirements of customers will become a trend in technology development.

[0004] In related technologies, halogen-free piperazine flame retardants, long glass fibers, and ceramic fillers are compounded to obtain a polypropylene composite material that has a certain ablation resistance. However, after thinning, the material is not resistant to fire and is easily burned through, and the material has a large deformation after ablation.

[0005] Therefore, it is an urgent problem in the field to develop a polypropylene composite material that is resistant to ablation, has a small deformation after ablation, and has good flame retardant properties and impact resistance. SUMMARY

[0006] The following is a summary of the subject matter described in detail in this document. This summary is not intended to limit the scope of protection of the claims.

[0007] The present application provides a polypropylene composite material and a preparation method and application thereof. The polypropylene composite material solves the problem of poor ablation resistance and large deformation after ablation of the polypropylene composite material in related technologies, and also ensures that the polypropylene composite material has a high flame retardant grade and excellent impact resistance.

[0008] In a first aspect, the present application provides a polypropylene composite material, which comprises a prepreg and a first polypropylene layer stacked in sequence; the first polypropylene layer comprises, by weight, 15-60 parts of a first polypropylene resin, 15-25 parts of a first piperazine flame retardant, 5-15 parts of a first nitrogen-phosphorus composite flame retardant, 0.1-2 parts of a first synergistic flame retardant, and 5-30 parts of long glass fibers.

[0009] In the present application, the polypropylene composition is compounded with a specific composition of flame retardant, long glass fiber and polypropylene resin, which is beneficial to improve the ablation resistance of the polypropylene composite material; by setting the prepreg, it is beneficial to reduce the deformation amount of the polypropylene composite material after ablation, and improve the impact resistance of the polypropylene composite material; by compounding the prepreg and the first polypropylene layer, the ablation-resistant polypropylene composite material has good ablation resistance and low deformation after ablation, and at the same time, the ablation-resistant polypropylene composite material has high flame retardant grade and good impact resistance.

[0010] In the present application, 15-60 parts of the first polypropylene resin, for example, can be 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts or a range between any of the above values.

[0011] In the present application, the mass percentage content of the first polypropylene resin in the first polypropylene layer is ≥15%, optionally ≥20%, and further optionally ≥30%.

[0012] In the present application, 15-25 parts of the first piperazine flame retardant, for example, can be 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 20.5 parts, 21 parts, 21.5 parts, 22 parts, 22.5 parts, 23 parts, 23.5 parts, 24 parts, 24.5 parts, 25 parts or a range between any of the above values.

[0013] In the present application, 5-15 parts of the first nitrogen-phosphorus composite flame retardant, for example, can be 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, 6 parts, 6.2 parts, 6.4 parts, 6.6 parts, 6.8 parts, 7 parts, 7.2 parts, 7.4 parts, 7.6 parts, 7.8 parts, 8 parts, 8.2 parts, 8.4 parts, 8.6 parts, 8.8 parts, 9 parts, 9.2 parts, 9.4 parts, 9.6 parts, 9.8 parts, 10 parts, 10.2 parts, 10.4 parts, 10.6 parts, 10.8 parts, 11 parts, 11.2 parts, 11.4 parts, 11.6 parts, 11.8 parts, 12 parts, 12.2 parts, 12.4 parts, 12.6 parts, 12.8 parts, 13 parts, 13.2 parts, 13.5 parts, 13.8 parts, 14 parts, 14.2 parts, 14.5 parts, 14.8 parts, 15 parts or a range between any of the above values.

[0014] In the present application, 0.1-2 parts of the first synergistic flame retardant, for example, can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts or a range consisting of any of the above values.

[0015] In the present application, 5-30 parts of the long glass fiber, for example, can be 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts or a range consisting of any of the above values.

[0016] In one embodiment, the first polypropylene resin comprises a homopolymer polypropylene and / or a copolymer polypropylene.

[0017] In the present application, the melt index of the first polypropylene resin is 10-200 g / 10 min, for example, can be 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 32 g / 10 min, 40 g / 10 min, 50 g / 10 min, 60 g / 10 min, 80 g / 10 min, 100 g / 10 min, 120 g / 10 min, 140 g / 10 min, 160 g / 10 min, 180 g / 10 min, 200 g / 10 min or a range consisting of any of the above values, according to the ISO 1133-1 standard, under the condition of 230℃, 2.16 kg.

[0018] In one embodiment, the first piperazine flame retardant comprises any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate or piperazine polyphosphate.

[0019] In one embodiment, the first nitrogen-phosphorus complex flame retardant comprises melamine pyrophosphate and / or melamine polyphosphate.

[0020] In an embodiment, the mass ratio of the first piperazine flame retardant to the first nitrogen-phosphorus composite flame retardant is (1.1-3.2):1, wherein the specific value in (1.1-3.2) can be, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, or a range between any of the above values; or optionally (1.4-2.2):1.

[0021] In an embodiment, the first synergistic flame retardant includes any one or a combination of at least two of zinc oxide, sepiolite, and zinc borate.

[0022] In an embodiment, the average retention length of the long glass fiber is >0.5 mm, for example, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, 1.65 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.85 mm, 1.9 mm, 1.95 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, 12 mm, 14 mm, 15 mm, or a range consisting of any of the above values; or optionally 1-3 mm.

[0023] In the present application, the factors affecting the average retention length of the long glass fiber include the type of long glass fiber (including the silica content), the original length of the long glass fiber, and the injection molding conditions (such as injection molding pressure or back pressure).

[0024] In the present application, the test method for the retention length of the long glass fiber includes calcining the polypropylene composite at 800°C for 2h to obtain ash, then dispersing the ash in a solvent (including ethanol, water, etc.), and using a two-dimensional measuring instrument to test the average retention length of the long glass fiber.

[0025] In an embodiment, the long glass fiber is added in the form of a long glass fiber master batch.

[0026] In one embodiment, the long glass fiber masterbatch has a long glass fiber content of 40-60% by weight, for example, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a range defined by any of the foregoing values.

[0027] In the present application, the long glass fiber masterbatch comprises resin and long glass fiber; the resin comprises polyolefin; and the polyolefin comprises polypropylene.

[0028] In the present application, the long glass fiber content in the first polypropylene layer refers to the content of pure long glass fiber, excluding the content of the matrix resin in the masterbatch.

[0029] In the present application, the long glass fiber masterbatch can be purchased on the market or prepared by a conventional method, for example, by extruding and granulating the commercially available resin and the commercially available long glass fiber at 160-200°C.

[0030] In one embodiment, the first polypropylene layer further comprises 1-5 parts of the first compatibilizer by weight, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or a range defined by any of the foregoing values.

[0031] In one embodiment, the first compatibilizer comprises maleic anhydride grafted polypropylene and / or maleic anhydride grafted polyolefin elastomer.

[0032] In one embodiment, the first polypropylene layer further comprises 0.3-1.2 parts of the first other auxiliary agent by weight, for example, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, or a range defined by any of the foregoing values.

[0033] In one embodiment, the first other auxiliary agent comprises an antioxidant and / or a lubricant.

[0034] In one embodiment, the prepreg comprises 18-32 parts of the second polypropylene resin, 40-60 parts of the second glass fiber, and 10-33 parts of the flame retardant by weight.

[0035] In one embodiment, the second glass fiber comprises continuous long glass fiber.

[0036] In the present application, the diameter of the continuous long glass fiber is ≥9μm, for example, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 22μm, 24μm, 26μm, 28μm, 30μm, or a range defined by any of the foregoing values.

[0037] In one embodiment, the flame retardant comprises 10-22 parts by weight of the second piperazine flame retardant, 1-10 parts by weight of the second nitrogen-phosphorus composite flame retardant, or 0.05-0.5 parts by weight of the second synergistic flame retardant.

[0038] In one embodiment, the prepreg further comprises 0.5-5.5 parts by weight of the second compatibilizer and / or 0-1 parts by weight of the second other auxiliary agent.

[0039] In the present application, the prepreg is compounded with the first polypropylene layer of a specific formula, and the obtained polypropylene composite material has better ablation resistance and lower deformation after ablation.

[0040] In the present application, the 18-32 parts by weight of the second polypropylene resin may, for example, be 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, or a range value between any of the above-mentioned values.

[0041] In the present application, the mass percentage content of the second polypropylene resin in the prepreg is ≥15%, and optionally ≥20%.

[0042] According to the ISO 1133-1 standard, the melt index of the second polypropylene resin is 30-200 g / 10 min at 230℃ and 2.16 kg, for example, it may be 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 50 g / 10 min, 60 g / 10 min, 70 g / 10 min, 80 g / 10 min, 90 g / 10 min, 100 g / 10 min, 120 g / 10 min, 140 g / 10 min, 160 g / 10 min, 180 g / 10 min, 200 g / 10 min, or a range consisting of any of the above-mentioned values. The second polypropylene resin and the first polypropylene resin may be the same or different, and the material with the corresponding melt index can be selected according to the specific application scenario.

[0043] In the present application, the 40-60 parts by weight of the second glass fiber may, for example, be 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, or a range between any of the above-mentioned values.

[0044] In the present application, the 10-33 parts by weight of the flame retardant may, for example, be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 33 parts, or a range between any of the above-mentioned values.

[0045] In this application, the specific values ​​of 10-22 parts of the second piperazine flame retardant can be, for example, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, or any range between the above values.

[0046] In this application, 1-10 parts of the second nitrogen-phosphorus composite flame retardant can be, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, or any range of the above values.

[0047] In this application, 0.05-0.5 parts of the second synergistic flame retardant can be, for example, 0.05 parts, 0.06 parts, 0.08 parts, 0.1 parts, 0.12 parts, 0.14 parts, 0.16 parts, 0.18 parts, 0.2 parts, 0.22 parts, 0.24 parts, 0.26 parts, 0.28 parts, 0.3 parts, 0.32 parts, 0.34 parts, 0.36 parts, 0.38 parts, 0.4 parts, 0.42 parts, 0.44 parts, 0.46 parts, 0.48 parts, 0.5 parts, or any combination of the above values.

[0048] In one embodiment, the prepreg further includes 0.5-5.5 parts by weight of a second compatibilizer and / or 0-1 parts by weight of a second other additive.

[0049] In this application, 0.5-5.5 parts of the second compatibilizer can be, for example, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, or any range of the above values.

[0050] In this application, 0-1 parts of the second other adjuvant can be, for example, 0 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, or any range between the above values.

[0051] In one embodiment, the second polypropylene resin comprises homopolymer polypropylene and / or copolymer polypropylene.

[0052] In one embodiment, the second piperazine flame retardant comprises any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate, or piperazine polyphosphate.

[0053] In one embodiment, the second nitrogen-phosphorus composite flame retardant comprises melamine pyrophosphate and / or melamine polyphosphate.

[0054] In one embodiment, the second synergistic flame retardant comprises any one or a combination of at least two of zinc oxide, sepiolite, and zinc borate.

[0055] In one embodiment, the second compatibilizer comprises maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted polyolefin elastomer.

[0056] In one embodiment, the second other additive includes antioxidants and / or lubricants.

[0057] In this application, the antioxidants in the first and second other additives are each independently including, but not limited to, at least one of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (antioxidant 445), and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098).

[0058] In this application, the lubricant in the first and second other additives is independently including, but is not limited to, at least one of ethylene bis-stearamide, erucamide, zinc stearate, or silicone oil.

[0059] In one embodiment, the number of layers of the prepreg is ≥1, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20 or any of the above values.

[0060] In one embodiment, the number of layers of the prepreg is greater than 1, and the layup of the prepreg includes co-directional layup or cross-layup, and can be selected as cross-layup.

[0061] In one embodiment, the total thickness of the prepreg is 0.15-0.85 mm, for example, it can be 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm or any value between the above; optionally, it can be 0.45-0.75 mm.

[0062] In one embodiment, the thickness of the polypropylene composite material is 0.5-3 mm, for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm or any range of the above values.

[0063] Secondly, this application provides a method for preparing the polypropylene composite material according to the first aspect, the method comprising the following steps:

[0064] The prepreg fabric is mixed with the material of the first polypropylene layer and molded to obtain the polypropylene composite material.

[0065] In one embodiment, the method for preparing the prepreg fabric includes:

[0066] The second glass fiber is mixed with the second polypropylene resin, a flame retardant, and optionally a second compatibilizer and / or other additives, and extruded to obtain a single-layer prepreg; then at least one single-layer prepreg is pressed into shape to obtain the prepreg.

[0067] In one embodiment, the extrusion temperature is 120-260°C, and the compression molding temperature is 100-300°C.

[0068] In this application, specifically, the method for preparing the prepreg includes: impregnating a second glass fiber in a molten mixture composed of a second polypropylene resin, a flame retardant, and optionally a second compatibilizer and / or other additives to obtain a single-layer prepreg; and then pressing at least one single-layer prepreg into shape to obtain the prepreg.

[0069] More specifically, the preparation method of the prepreg includes: first, mixing the components other than the second glass fiber, extruding and granulating them at a temperature below 200°C to obtain a flame-retardant masterbatch; then, melting the flame-retardant masterbatch and continuously extruding it through a die to impregnate the second glass fiber at a high temperature to obtain a single-layer prepreg; when the number of prepreg layers is greater than 1, at least 2 layers of prepreg are laid up in the same direction and / or in a cross-laminated manner, and then pressed to obtain the prepreg.

[0070] In one embodiment, the method of mixing the prepreg with the material of the first polypropylene layer includes: placing the prepreg in a mold and then injecting the material of the first polypropylene layer therein for mixing.

[0071] In one embodiment, the molding method includes at least one of injection molding, extrusion molding, or compression molding, with injection molding being an option.

[0072] In one embodiment, after the prepreg is mixed with the material of the first polypropylene layer, the molding temperature is 100-400°C and the pressure is 50-180 MPa.

[0073] In one embodiment, after the prepreg is mixed with the material of the first polypropylene layer, the molding pressure is 10-150 MPa and the holding time is 5-300 s.

[0074] Thirdly, this application provides an ablation-resistant polypropylene profile, which is prepared using the polypropylene composite material described in the first aspect.

[0075] In this application, the structure of the ablation-resistant polypropylene profile can be any shape, which can be selected according to actual needs, including but not limited to plates, sheets, films, and pipes. The plates can be flat plates or irregularly shaped plates.

[0076] Fourthly, this application provides an article comprising the ablation-resistant polypropylene composite material described in the first aspect, the article comprising a battery pack cover.

[0077] In this application, the articles described are not limited to battery pack covers, but also include household items, electronic components, home appliances, gardening equipment, medical technology equipment, motor vehicle parts, and vehicle body parts. Specifically, they include, for example, battery racks and covers in electric vehicles; automotive parts such as bumpers, dashboard carriers, door modules, rear bumpers, front-end modules, accelerator pedal boxes, airbag shells, air ducts, and sunroof structures; and housings of household appliances such as washing machines, dryers, coffee makers, toasters, refrigerators, and vacuum cleaners.

[0078] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0079] Compared with related technologies, the beneficial effects of this application are as follows:

[0080] The polypropylene composite material provided in this application is compounded by a first polypropylene layer obtained by prepreg and a specific formulation, which makes the polypropylene composite material have both good ablation resistance and low deformation after ablation. At the same time, the polypropylene composite material has a high flame retardant rating and good impact resistance.

[0081] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0082] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0083] All materials used in this application are commercially available or prepared using conventional methods; unless otherwise specified, the materials used in this application are as follows:

[0084] PP-1: Homopolymer polypropylene granules, grade HP500N, CNOOC Shell.

[0085] PP-2: Copolymer polypropylene granules, grade EP548R, CNOOC Shell.

[0086] PP-3: Huajin Chemical H561S polypropylene.

[0087] Long glass fiber masterbatch GF-1:

[0088] 50 parts of glass fiber (grade SE4849, purchased from Owens Corning), 48 parts of polypropylene (PP-1), 1.5 parts of maleic anhydride-grafted polypropylene (Xingyuan Chemical, XYJ1210), 0.25 parts of antioxidant 1010 and 0.25 parts of antioxidant 168 were mixed and a long glass fiber masterbatch with a length of 10 mm and a glass fiber mass percentage of 50% was prepared by using an LFT-G impregnation equipment.

[0089] Second fiberglass: Jushi ER14-2000-988A;

[0090] Antioxidants: Antioxidant 1010, commercially available; Antioxidant 168, commercially available, with a mass ratio of 1:1.

[0091] Lubricant: Ethylene bis-stearamide (EBS), commercially available;

[0092] Melamine pyrophosphate: purchased from Hubei Xinmingtai Chemical Co., Ltd.;

[0093] Melamine polyphosphate: purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.;

[0094] Sepiolite: Purchased from Yitian Mining;

[0095] Maleic anhydride-grafted polypropylene: PP-g-MAH: Xingyuan Chemical, XYJ1210;

[0096] Maleic anhydride-grafted polyolefin elastomer: POE-g-MAH: Dow Chemical, USA, AMPLIFY GR216;

[0097] Piperazine pyrophosphate, piperazine phosphate, zinc oxide, and zinc borate are all commercially available.

[0098] Examples 1-14, Comparative Examples 1-6

[0099] Examples 1-14 and Comparative Examples 1-6 each provide a polypropylene composite material, comprising a prepreg and a first polypropylene layer stacked sequentially; the formulations of the prepreg and the first polypropylene layer, and the thickness of the prepreg, are shown in Tables 1-4 by weight, wherein " / " indicates that the component is not in the formulation; the preparation method of the polypropylene composite material includes the following steps:

[0100] A second polypropylene resin, a flame retardant, and optional compatibilizers, antioxidants, and lubricants are mixed and plasticized at 180°C. The mixture is then continuously extruded after being impregnated with a second glass fiber at a high temperature (220°C) through a die to obtain a single-layer prepreg. At least one layer of the single-layer prepreg is then laid up (either in a unidirectional or interlaced manner) and pressed at 220°C to obtain the prepreg. The prepreg is then fixed in a mold, and the material of the first polypropylene layer is injected into it, followed by injection molding to obtain the polypropylene composite material. The specific process parameters for injection molding are: injection molding temperature of 210°C and pressure of 80 MPa; the holding pressure of the injection molding is 50 MPa, and the holding time is 60 s.

[0101]

[0102] Performance testing

[0103] The following performance tests were conducted on the ablation-resistant polypropylene composite materials provided in Examples 1-14 and Comparative Examples 1-6:

[0104] (1) Flame retardant performance: Refer to UL 94, 1.5 mm flame retardant sample vertically burned;

[0105] (2) Burn-through resistance: A 1.5 mm square plate was continuously burned at 1000℃ for 10 minutes. Observe whether the square plate was burned through;

[0106] (3) Deformation after ablation: Measure the transverse and longitudinal dimensions of the polypropylene composite material before and after ablation, calculate the deformation before and after ablation, and take the average value of the deformation of the transverse and longitudinal dimensions.

[0107] (4) Impact resistance of falling ball: A 5 kg ball is dropped from a certain height directly above the polypropylene composite material, and the height at which the composite material breaks is recorded.

[0108] The specific test results are shown in Table 5.

[0109]

[0110] As shown in Table 5, the polypropylene composite material provided in this application, through the compounding of a first polypropylene layer obtained by prepreg and a specific formulation, enables the polypropylene composite material to possess both good ablation resistance and low deformation after ablation. Simultaneously, the polypropylene composite material exhibits a high flame retardancy rating and good impact resistance. The ablation-resistant polypropylene composite material has a high flame retardancy rating, reaching V-0; the drop ball impact fracture height is ≥2.0 m; it is resistant to 1000℃ flame ablation with minimal deformation after ablation, ≤3.0 mm.

[0111] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A polypropylene composite material comprising a prepreg and a first polypropylene layer stacked sequentially; By weight, the first polypropylene layer comprises 15-60 parts of first polypropylene resin, 15-25 parts of first piperazine flame retardant, 5-15 parts of first nitrogen-phosphorus composite flame retardant, 0.1-2 parts of first synergistic flame retardant and 5-30 parts of long glass fiber.

2. The polypropylene composite of claim 1, wherein, The first polypropylene resin includes homopolymer polypropylene and / or copolymer polypropylene.

3. The polypropylene composite material according to claim 1 or 2, wherein, The first piperazine flame retardant includes any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate, or piperazine polyphosphate.

4. The polypropylene composite material according to any one of claims 1 to 3, wherein, The first nitrogen-phosphorus composite flame retardant includes melamine pyrophosphate and / or melamine polyphosphate.

5. The polypropylene composite material according to any one of claims 1 to 4, wherein, The mass ratio of the first piperazine flame retardant to the first nitrogen-phosphorus composite flame retardant is (1.1-3.2):1, and can be selected as (1.4-2.2):

1.

6. The polypropylene composite of any one of claims 1-5, wherein, The first synergistic flame retardant includes any one or a combination of at least two of zinc oxide, sepiolite, and zinc borate.

7. The polypropylene composite of any one of claims 1-6, wherein, The long glass fibers are added in the form of long glass fiber masterbatch; Optionally, the long glass fiber masterbatch contains 40-60% by mass of long glass fibers.

8. The polypropylene composite material according to any one of claims 1 to 7, wherein, The first polypropylene layer further includes 1-5 parts of a first compatibilizer by weight; Optionally, the first compatibilizer comprises maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted polyolefin elastomer. Optionally, the first polypropylene layer further includes 0.3-1.2 parts by weight of a first other additive; Optionally, the first other additives include antioxidants and / or lubricants.

9. The polypropylene composite of any one of claims 1-8, wherein, By weight, the prepreg comprises 18-32 parts of second polypropylene resin, 40-60 parts of second glass fiber and 10-33 parts of flame retardant; Optionally, the second glass fiber comprises continuous long glass fibers; Optionally, by weight, the flame retardant includes at least one of 10-22 parts of a second piperazine flame retardant, 1-10 parts of a second nitrogen-phosphorus composite flame retardant, or 0.05-0.5 parts of a second synergistic flame retardant; Optionally, the prepreg may further include 0.5-5.5 parts by weight of a second compatibilizer and / or 0-1 parts by weight of a second other additive.

10. The polypropylene composite of claim 9, wherein, The second polypropylene resin includes homopolymer polypropylene and / or copolymer polypropylene; Optionally, the second piperazine flame retardant includes any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate, or piperazine polyphosphate; Optionally, the second nitrogen-phosphorus composite flame retardant includes melamine pyrophosphate and / or melamine polyphosphate; Optionally, the second synergistic flame retardant includes any one or a combination of at least two of zinc oxide, sepiolite, and zinc borate; Optionally, the second compatibilizer comprises maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted polyolefin elastomer. Optionally, the second additional additive includes antioxidants and / or lubricants.

11. The polypropylene composite of any one of claims 1-10, wherein, The number of layers in the prepreg is ≥1; Optionally, the number of layers of the prepreg is greater than 1, and the layup method of the prepreg includes co-directional layup or cross-layup, and can be selected as cross-layup. Optionally, the total thickness of the prepreg is 0.15-0.85 mm; optionally, it is 0.45-0.75 mm. Optionally, the thickness of the polypropylene composite material is 0.5-3 mm.

12. A method for preparing a polypropylene composite material according to any one of claims 1-11, comprising the following steps: The prepreg fabric is mixed with the material of the first polypropylene layer and molded to obtain the polypropylene composite material.

13. The production method according to claim 12, wherein The method for preparing the prepreg includes: The second glass fiber is mixed with the second polypropylene resin, a flame retardant, and optionally a second compatibilizer and / or other second additives, and extruded to obtain a single-layer prepreg; then at least one layer of the single-layer prepreg is pressed into shape to obtain the prepreg. Optionally, the extrusion temperature is 120-260°C, and the compression molding temperature is 100-300°C; Optionally, the method for mixing the prepreg fabric with the material of the first polypropylene layer includes: placing the prepreg fabric in a mold, and then injecting the material of the first polypropylene layer therein for mixing; Optionally, the molding method includes at least one of injection molding, extrusion molding, or compression molding; Optionally, after the prepreg is mixed with the material of the first polypropylene layer, the molding temperature is 100-400℃ and the pressure is 50-180 MPa. Optionally, after the prepreg is mixed with the material of the first polypropylene layer, the molding pressure is 10-150 MPa and the molding time is 5-300 s.

14. A ablative polypropylene profile, wherein, The ablation-resistant polypropylene profile is prepared using the polypropylene composite material described in any one of claims 1-11.

15. An article comprising the polypropylene composite of any of claims 1-11, wherein, The product includes a battery pack cover.

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