Polypropylene composite material as well as preparation method and application thereof

Abstract

The invention provides a polypropylene composite material as well as a preparation method and application thereof. The polypropylene composite material comprises prepreg cloth and a first polypropylene layer which are stacked in sequence, the first polypropylene layer comprises the following components in parts by weight: 15-60 parts of 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. According to the present invention, the polypropylene composite material has advantages of good ablation resistance, low post-ablation deformation, high flame retardant grade and good impact resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a polypropylene composite material and a preparation method and application thereof. Background Art

[0002] With the vigorous development of the new energy industry, the installed capacity of power batteries and energy storage batteries has reached new highs. As one of the components of power batteries and energy storage batteries, the battery pack cover is mainly made of metal or thermosetting materials, which have disadvantages such as high specific gravity, low processing efficiency and environmental pollution. With the continuous advancement of the country's dual-carbon policy, thermoplastic materials have been rapidly promoted and applied due to their light specific gravity and green environmental protection advantages.

[0003] At present, polypropylene (PP) is a commonly used thermoplastic material for battery pack covers. However, the core requirement of battery packs is that they need to pass the GB / T31467.3-2015 fire resistance test, and that no large amount of toxic and harmful gases are produced during the combustion process. Conventional PP can no longer meet the existing requirements. Therefore, in order to meet the testing requirements of customers, the development of low-smoke, halogen-free, ablation-resistant and heat-insulating flame-retardant enhanced PP will become a trend in technological development.

[0004] In the prior art, halogen-free piperazine flame retardant, long glass fiber and ceramic filler are compounded to obtain polypropylene composite materials with certain ablation resistance effect, but the thin-walled material is not fire-resistant and is easy to burn through, and the material deformation after ablation is large.

[0005] Therefore, developing a polypropylene composite material that is resistant to ablation, has a small amount of deformation after ablation, and has good flame retardant properties and resistance to falling ball impact is an urgent problem to be solved in the field. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a polypropylene composite material and a preparation method and application thereof. The polypropylene composite material solves the problems of the prior art polypropylene composite material being poor in ablation resistance and having large deformation after ablation, while also ensuring that the polypropylene composite material has a high flame retardant grade and excellent impact resistance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

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

[0009] In the present invention, the polypropylene composition is compounded with a flame retardant of a specific composition, long glass fibers and polypropylene resin, which is beneficial to improving the ablation resistance of the polypropylene composite material; by providing a prepreg, it is beneficial to reduce the deformation of the polypropylene composite material after ablation and improve the falling ball impact resistance of the polypropylene composite material; by compounding the prepreg and the injection molding layer, the ablation-resistant polypropylene composite material has both good ablation resistance and low deformation after ablation, and at the same time, the ablation-resistant polypropylene composite material has a high flame retardant grade and good impact resistance.

[0010] In the present invention, 15 to 60 parts of the first polypropylene resin can be, for example, 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 invention, the mass percentage of the first polypropylene resin in the first polypropylene layer is ≥15%, more preferably ≥20%, and particularly preferably ≥30%.

[0012] In the present invention, 15 to 25 parts of the first piperazine flame retardant can be, for example, 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 invention, 5 to 15 parts of the first nitrogen-phosphorus composite flame retardant can be, for example, 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 , 14.2 parts, 14.5 parts, 14.8 parts, 15 parts, or a range between any of the above values.

[0014] In the present invention, 0.1 to 2 parts of the first synergistic flame retardant can be, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, 1.1 part, 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 invention, 5 to 30 parts of long glass fibers can be, for example, 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] Preferably, the first polypropylene resin comprises homopolypropylene and / or copolymer polypropylene.

[0017] In the present invention, at 230°C and 2.16kg, the melt index of the first polypropylene resin is 10 to 200 g / 10min, for example, 10 g / 10min, 12 g / 10min, 14 g / 10min, 16 g / 10min, 18 g / 10min, 20 g / 10min, 22 g / 10min, 24 g / 10min, 26 g / 10min, 28 g / 10min, 30 g / 10min, 32 g / 10min or a range consisting of any of the above values.

[0018] Preferably, the first piperazine flame retardant includes any one of piperazine phosphate, piperazine pyrophosphate or piperazine polyphosphate, or a combination of at least two thereof.

[0019] Preferably, the first nitrogen-phosphorus composite flame retardant includes melamine pyrophosphate and / or melamine polyphosphate.

[0020] Preferably, 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; more preferably (1.4-2.2):1.

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

[0022] Preferably, the average retention length of the long glass fibers is greater than 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, 2.1 mm, 2.25 mm, 2.3 mm, 2.4 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 3.1 mm, 3.2 mm, 3. 1 to 3 mm; and more preferably, 1 to 3 mm.

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

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

[0025] Preferably, the long glass fibers are added in the form of long glass fiber masterbatch.

[0026] Preferably, the mass percentage of the long glass fiber in the long glass fiber masterbatch is 40-60%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60% or a range consisting of any of the above values.

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

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

[0029] In the present invention, the long glass fiber masterbatch can be purchased from the market, or prepared by conventional methods, such as by extruding and granulating commercially available resin and commercially available long glass fibers at 160-200°C.

[0030] Preferably, the first polypropylene layer further comprises 1 to 5 parts of a first compatibilizer, by weight, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts or any range thereof.

[0031] Preferably, the first compatibilizer comprises polypropylene grafted with maleic anhydride and / or polyolefin elastomer grafted with maleic anhydride.

[0032] Preferably, the first polypropylene layer further comprises 0.3 to 1.2 parts of the first other auxiliary agent in parts by weight, for example, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts or any range thereof.

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

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

[0035] Preferably, the second glass fibers include continuous long glass fibers.

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

[0037] Preferably, the flame retardant includes at least one of 10 to 22 parts of a second piperazine flame retardant, 1 to 10 parts of a second nitrogen-phosphorus composite flame retardant, or 0.05 to 0.5 parts of a second synergistic flame retardant, in parts by weight.

[0038] Preferably, the prepreg further comprises, by weight, 0.5 to 5.5 parts of a second compatibilizer and / or 0 to 1 part of a second other auxiliary agent.

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

[0040] In the present invention, 18 to 32 parts of the second polypropylene resin can be, for example, 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 between any of the above values.

[0041] In the present invention, the mass percentage of the second polypropylene resin in the prepreg is ≥15%, more preferably ≥20%.

[0042] At 230°C and 2.16kg, the melt index of the second polypropylene resin is 30 to 200 g / 10min, for example, 30 g / 10min, 35 g / 10min, 40 g / 10min, 50 g / 10min, 60 g / 10min, 70 g / 10min, 80 g / 10min, 90 g / 10min, 100 g / 10min, 120 g / 10min, 140 g / 10min, 160 g / 10min, 180 g / 10min, 200 g / 10min or any range thereof. The second polypropylene resin may be the same as or different from the first polypropylene resin, and the material with the corresponding melt index may be selected according to the specific application scenario.

[0043] In the present invention, 40 to 60 parts of the second glass fiber can be, for example, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts or any range between the above values.

[0044] In the present invention, 10 to 33 parts of flame retardant can be, for example, 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 values.

[0045] In the present invention, the specific value of 10 to 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 a range between any of the above values.

[0046] In the present invention, 1 to 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 a range between any of the above values.

[0047] In the present invention, 0.05 to 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 a range consisting of any of the above values.

[0048] Preferably, the prepreg further comprises, by weight, 0.5 to 5.5 parts of a second compatibilizer and / or 0 to 1 part of a second other auxiliary agent.

[0049] In the present invention, 0.5 to 5.5 parts of the second compatibilizer can be, for example, 0.5 parts, 1 parts, 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 between the above values.

[0050] In the present invention, 0 to 1 part of the second other auxiliary agent can be, for example, 0 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part or a range between any of the above values.

[0051] Preferably, the second polypropylene resin comprises homopolypropylene and / or copolymer polypropylene.

[0052] Preferably, the second piperazine flame retardant includes any one of piperazine phosphate, piperazine pyrophosphate or piperazine polyphosphate, or a combination of at least two thereof.

[0053] Preferably, the second nitrogen-phosphorus composite flame retardant includes melamine pyrophosphate and / or melamine polyphosphate.

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

[0055] Preferably, the second compatibilizer comprises polypropylene grafted with maleic anhydride and / or polyolefin elastomer grafted with maleic anhydride.

[0056] Preferably, the second other auxiliary agent comprises an antioxidant and / or a lubricant.

[0057] In the present invention, the antioxidants in the first other auxiliary agent and the second other auxiliary agent independently include but are not limited to at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester (antioxidant 1010), tris[2.4-di-tert-butylphenyl]phosphite (antioxidant 168), 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)hexanediamine (antioxidant 1098).

[0058] In the present invention, the lubricants in the first other auxiliary agent and the second other auxiliary agent independently include, but are not limited to, at least one of ethylene bisstearamide, erucamide, zinc stearate or silicone oil.

[0059] Preferably, 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 a range between any of the above values.

[0060] Preferably, the number of layers of the prepreg is greater than 1, and the plying method of the prepreg includes plying in the same direction or plying in a criss-cross manner, preferably plying in a criss-cross manner.

[0061] Preferably, 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 a range between any of the above values; preferably 0.45-0.75 mm.

[0062] Preferably, 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 a range between any of the above values.

[0063] In a second aspect, the present invention provides a method for preparing the polypropylene composite material according to the first aspect, the preparation method comprising the following steps:

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

[0065] Preferably, the method for preparing the prepreg comprises:

[0066] The second glass fiber is mixed with the second polypropylene resin, the flame retardant and the optional second other auxiliary agent, and extruded to obtain a single-layer prepreg cloth; and then at least one layer of the single-layer prepreg cloth is pressed into shape to obtain the prepreg cloth.

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

[0068] In the present invention, specifically, the method for preparing the prepreg comprises: impregnating a second glass fiber into a molten mixture consisting of a second polypropylene resin, a flame retardant and an optional second other auxiliary agent to obtain a single-layer prepreg; and then pressing and molding at least one layer of the single-layer prepreg to obtain the prepreg.

[0069] More specifically, the preparation method of the prepreg includes: firstly mixing the other components except the second glass fiber, extruding and granulating at a temperature less than 200°C to obtain a flame retardant masterbatch; then, the flame retardant masterbatch is melted and then continuously extruded after being impregnated with the second glass fiber at high temperature through a die head to obtain a single-layer prepreg; when the number of prepreg layers is greater than 1, at least 2 layers of prepreg are laid in the same direction and / or in a criss-cross manner, and pressed and formed to obtain the prepreg. Preferably, the method of mixing the prepreg with the material of the first polypropylene layer includes: arranging the prepreg in a mold, and then injecting the material of the first polypropylene layer into it for mixing.

[0070] Preferably, the molding method includes at least one of injection molding, extrusion molding or compression molding, preferably injection molding.

[0071] Preferably, 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.

[0072] Preferably, after the prepreg is mixed with the material of the first polypropylene layer, the holding pressure during molding is 10 to 150 MPa, and the holding time is 5 to 300 s.

[0073] In a third aspect, the present invention provides an ablation-resistant polypropylene profile, wherein the ablation-resistant polypropylene profile is prepared by using the polypropylene composite material described in the first aspect.

[0074] In the present invention, the structure of the ablation-resistant polypropylene profile can be in any shape, which can be selected according to actual needs, including but not limited to plates, sheets, membranes, and pipes. The plates can be flat plates or special-shaped plates.

[0075] In a fourth aspect, the present invention provides a product comprising the ablation-resistant polypropylene composite material described in the first aspect, wherein the product comprises a battery pack cover.

[0076] In the present invention, the products are not limited to battery pack covers, but also include household items, electronic components, household appliances, gardening equipment, medical technology equipment, motor vehicle parts and body parts, etc. In particular, for example, they include battery racks and covers in electric vehicles, automotive parts such as bumpers, instrument panel carriers, door modules, tailgates, front modules, accelerator pedal boxes, airbag housings, air ducts and sunroof structures, etc.; household appliance housings, such as washing machines, dryers, coffee machines, toasters, refrigerators, vacuum cleaners, etc.

[0077] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] The polypropylene composite material provided by the present invention is compounded with a prepreg cloth and a first polypropylene layer obtained by a specific formula, so that the polypropylene composite material has both good ablation resistance and low deformation after ablation, and at the same time, the polypropylene composite material has a high flame retardant grade and good impact resistance. DETAILED DESCRIPTION

[0080] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0081] The materials used in the present invention can be purchased from the market or prepared by conventional methods; unless otherwise specified, the materials used in the present invention are as follows:

[0082] PP-1: Homopolymer polypropylene pellets, brand HP500N, CNOOC and Shell.

[0083] PP-2: Copolymer polypropylene pellets, brand EP548R, CNOOC and Shell.

[0084] PP-3: Huajin Chemical H561S polypropylene.

[0085] Long glass fiber masterbatch GF-1:

[0086] 50 parts of glass fiber (brand 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 content of 50% was obtained by using LFT-G impregnation equipment.

[0087] Second fiberglass: Jushi ER14-2000-988A;

[0088] Antioxidant: Antioxidant 1010, commercially available; Antioxidant 168, commercially available, the mass ratio of the two is 1:1.

[0089] Lubricant: Ethylene bis stearamide EBS, commercially available;

[0090] Melamine pyrophosphate: purchased from Hubei Xinmingtai Chemical Co., Ltd.;

[0091] Melamine polyphosphate: purchased from Wuhan Jixinyibang Biotechnology Co., Ltd.;

[0092] Sepiolite: purchased from Yitian Mining;

[0093] Maleic anhydride grafted polypropylene: PP-g-MAH: Xingyuan Chemical, XYJ1210;

[0094] Maleic anhydride grafted polyolefin elastomer: POE-g-MAH: Dow, USA, AMPLIFY GR216;

[0095] Piperazine pyrophosphate, piperazine phosphate, zinc oxide, and zinc borate can all be purchased commercially.

[0096] Examples 1 to 14, Comparative Examples 1 to 6

[0097] Examples 1 to 14 and Comparative Examples 1 to 6 respectively provide a polypropylene composite material, comprising a prepreg and a first polypropylene layer stacked in sequence; in parts by weight, the formula of the prepreg and the first polypropylene layer and the thickness of the prepreg are shown in Tables 1 to 4, wherein “ / ” indicates that the component is not included in the formula; the preparation method of the polypropylene composite material comprises the following steps:

[0098] A second polypropylene resin, a flame retardant, and an optional antioxidant and a lubricant are mixed, plasticized at 180°C, and continuously extruded after being impregnated with a second glass fiber at a high temperature (220°C) of a die head to obtain a single-layer prepreg cloth; then at least one layer of the single-layer prepreg cloth is laid (laid in the same direction or in a criss-cross manner), and pressed and molded at 220°C to obtain the prepreg cloth; then the prepreg cloth is fixed in a mold, and the material of the first polypropylene layer is injected therein, and injection molding is performed to obtain the polypropylene composite material; the specific process parameters of the injection molding are: the injection molding temperature is 210°C, the pressure is 80MPa; the holding pressure of the injection molding is 50MPa, and the holding time is 60s.

[0099] Table 1

[0100]

[0101]

[0102] Table 2

[0103]

[0104] Table 3

[0105]

[0106]

[0107] Table 4

[0108]

[0109]

[0110] Performance Testing

[0111] The following performance tests were performed on the ablation-resistant polypropylene composite materials provided in Examples 1 to 14 and Comparative Examples 1 to 6:

[0112] (1) Flame retardant performance: refer to UL 94, 1.5mm flame retardant specimen vertical combustion;

[0113] (2) Burn-through resistance: Burn a 1.5 mm square plate at 1000°C for 10 minutes. Observe whether the square plate is burned through.

[0114] (3) Deformation degree after ablation: The transverse and longitudinal dimensions of the polypropylene composite material before and after ablation were measured, and the deformation before and after ablation was calculated. The deformation of the transverse and longitudinal dimensions was averaged;

[0115] (4) Ball impact resistance: A 5 kg ball was dropped from a certain height directly above the polypropylene composite material, and the height at which the composite material broke was recorded.

[0116] The specific test results are shown in Table 5.

[0117] Table 5

[0118]

[0119] As shown in Table 5, the polypropylene composite material provided by the present invention is compounded by prepreg and the first polypropylene layer obtained by a specific formula, so that the polypropylene composite material has both good ablation resistance and low deformation after ablation, and at the same time, the polypropylene composite material has a high flame retardant grade and good impact resistance. The ablation-resistant polypropylene composite material has a high flame retardant grade, reaching V-0 grade; the height of the falling ball impact rupture is ≥2.0m; it is resistant to 1000℃ flame ablation and has a small deformation after ablation, ≤3.0mm.

[0120] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polypropylene composite material, characterized in that: The polypropylene composite material comprises a prepreg cloth and a first polypropylene layer stacked in sequence; In parts by weight, the first polypropylene layer includes 15 to 60 parts of a first polypropylene resin, 15 to 25 parts of a first piperazine flame retardant, 5 to 15 parts of a first nitrogen-phosphorus composite flame retardant, 0.1 to 2 parts of a first synergistic flame retardant and 5 to 30 parts of long glass fibers.

2. The polypropylene composite material according to claim 1, characterized in that: The first polypropylene resin includes homopolypropylene and / or copolymer polypropylene; Preferably, the first piperazine flame retardant includes any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate or piperazine polyphosphate; Preferably, the first nitrogen-phosphorus composite flame retardant comprises melamine pyrophosphate and / or melamine polyphosphate; Preferably, the mass ratio of the first piperazine flame retardant to the first nitrogen-phosphorus composite flame retardant is (1.1-3.2):1, more preferably (1.4-2.2):1; Preferably, the first synergistic flame retardant includes any one of zinc oxide, sepiolite and zinc borate, or a combination of at least two thereof.

3. The polypropylene composite material according to claim 1 or 2, characterized in that: The long glass fiber is added in the form of long glass fiber masterbatch; Preferably, the mass percentage of long glass fiber in the long glass fiber masterbatch is 40-60%; Preferably, the first polypropylene layer further comprises 1 to 5 parts by weight of a first compatibilizer; Preferably, the first compatibilizer comprises polypropylene grafted with maleic anhydride and / or polyolefin elastomer grafted with maleic anhydride; Preferably, the first polypropylene layer further comprises 0.3 to 1.2 parts by weight of a first other auxiliary agent; Preferably, the first other auxiliary agent comprises an antioxidant and / or a lubricant.

4. The polypropylene composite material according to any one of claims 1 to 3, characterized in that: The prepreg comprises, by weight, 18 to 32 parts of a second polypropylene resin, 40 to 60 parts of a second glass fiber, and 10 to 33 parts of a flame retardant; Preferably, the second glass fibers include continuous long glass fibers; Preferably, the flame retardant includes at least one of 10 to 22 parts of a second piperazine flame retardant, 1 to 10 parts of a second nitrogen-phosphorus composite flame retardant, or 0.05 to 0.5 parts of a second synergistic flame retardant, in parts by weight; Preferably, the prepreg further comprises, by weight, 0.5 to 5.5 parts of a second compatibilizer and / or 0 to 1 part of a second other auxiliary agent.

5. The polypropylene composite material according to claim 4, characterized in that: The second polypropylene resin includes homopolypropylene and / or copolymer polypropylene; Preferably, the second piperazine flame retardant includes any one or a combination of at least two of piperazine phosphate, piperazine pyrophosphate or piperazine polyphosphate; Preferably, the second nitrogen-phosphorus composite flame retardant comprises melamine pyrophosphate and / or melamine polyphosphate; Preferably, the second synergistic flame retardant comprises any one or a combination of at least two of zinc oxide, sepiolite and zinc borate; Preferably, the second compatibilizer comprises polypropylene grafted with maleic anhydride and / or polyolefin elastomer grafted with maleic anhydride; Preferably, the second other auxiliary agent comprises an antioxidant and / or a lubricant.

6. The polypropylene composite material according to any one of claims 1 to 5, characterized in that: The number of layers of the prepreg is ≥1; Preferably, the number of layers of the prepreg is greater than 1, and the laying method of the prepreg includes a unidirectional laying method or a criss-cross laying method, and more preferably a criss-cross laying method; Preferably, the total thickness of the prepreg is 0.15 to 0.85 mm; preferably 0.45 to 0.75 mm; Preferably, the thickness of the polypropylene composite material is 0.5-3 mm.

7. A method for preparing a polypropylene composite material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The prepreg cloth is mixed with the material of the first polypropylene layer and molded to obtain the polypropylene composite material.

8. The preparation method according to claim 7, characterized in that: The preparation method of the prepreg comprises: The second glass fiber is mixed with the second polypropylene resin, the flame retardant and the optional second other auxiliary agent, and extruded to obtain a single-layer prepreg; and then at least one layer of the single-layer prepreg is pressed and formed to obtain the prepreg; Preferably, the extrusion temperature is 120-260°C, and the compression molding temperature is 100-300°C; Preferably, the method of mixing the prepreg with the material of the first polypropylene layer comprises: arranging the prepreg in a mold, and then injecting the material of the first polypropylene layer therein for mixing; Preferably, the molding method includes at least one of injection molding, extrusion molding or compression molding; Preferably, after the prepreg is mixed with the material of the first polypropylene layer, the molding temperature is 100 to 400° C. and the pressure is 50 to 180 MPa; Preferably, after the prepreg is mixed with the material of the first polypropylene layer, the holding pressure during molding is 10 to 150 MPa, and the holding time is 5 to 300 s.

9. An ablation-resistant polypropylene profile, characterized in that: The ablation-resistant polypropylene profile is prepared by using the polypropylene composite material according to any one of claims 1 to 6.

10. A product comprising the polypropylene composite material according to any one of claims 1 to 6, characterized in that: The product includes a battery pack upper cover.

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