Halogen-free flame-retardant prepreg layer and polypropylene composite comprising the same

Abstract

This invention discloses a halogen-free flame-retardant prepreg and a polypropylene composite material comprising the same. The halogen-free flame-retardant prepreg comprises fiberglass cloth and prepreg, wherein the fiberglass cloth in the prepreg has a thickness of 0.2–0.4 mm and a basis weight of 150–450 g / m³. 2 The thickness of the halogen-free flame-retardant prepreg layer is 0.3–0.8 mm. By combining the halogen-free flame-retardant prepreg layer with the ablation-resistant polypropylene composition layer, the thickness of the polypropylene composite part can be compressed to no more than 1.8 mm, and the polypropylene composite material has good ablation resistance and drop ball impact resistance, as well as good self-supporting properties.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic plastics technology, and more specifically, relates to a halogen-free flame-retardant prepreg and a polypropylene composite material including the prepreg. Background Technology

[0002] The new energy industry is booming, with a surge in the installation of power batteries and energy storage batteries, creating a strong market momentum. Among these, the battery pack, as a core component for energy storage and conversion, directly affects the stable operation of the entire system and user safety. According to the domestic standard GB / T31467.3-2015, battery packs must pass rigorous fire resistance tests, and the emission of toxic and harmful gases must be strictly controlled during combustion.

[0003] Existing technologies utilize compounding agents such as piperazine salts and melamine salts to achieve ablation resistance in thin-walled polypropylene composites. However, with the increasing trend towards thinner walls in large components such as battery covers for new energy vehicles, these technologies cannot meet the requirements for high ablation resistance, reduced backside temperature, and improved drop ball impact resistance. Therefore, there is a need in this field to develop a thin-walled polypropylene composite material with both good ablation resistance and good drop ball impact resistance. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects or deficiencies of poor ablation resistance and drop ball impact resistance of thin-walled polypropylene composite materials in the prior art, and to provide a halogen-free flame-retardant prepreg layer and a polypropylene composite material including the prepreg.

[0005] Another object of the present invention is to provide a method for preparing the halogen-free flame-retardant prepreg layer.

[0006] Another object of the present invention is to provide a method for preparing the polypropylene composite material.

[0007] Another object of the present invention is to provide applications of the said polypropylene composite material.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A halogen-free flame-retardant prepreg layer comprises fiberglass cloth and prepreg, wherein the fiberglass cloth in the prepreg layer has a thickness of 0.2–0.4 mm and a basis weight of 150–450 g / m². 2 The thickness of the halogen-free flame-retardant prepreg layer is 0.3 to 0.8 mm.

[0010] Furthermore, the prepreg comprises the following components in parts by weight:

[0011]

[0012] Furthermore, the flame retardant content in the prepreg is not less than 28 wt%, such as, but not limited to, not less than 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 37 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, or 60 wt%, etc., and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the specific values ​​included in the range will not be exhaustively listed in this invention.

[0013] Furthermore, the flame retardant content in the prepreg is 33wt% to 55wt%.

[0014] Furthermore, the flame retardant includes piperazine salts and melamine salts.

[0015] It should be noted that the thickness of the halogen-free flame-retardant prepreg layer described in this invention can be controlled by adjusting the thickness of the glass fiber cloth and the amount of prepreg impregnation.

[0016] Furthermore, the thickness of the halogen-free flame-retardant prepreg layer described in this invention is 0.3 to 0.8 mm, for example, but not limited to, 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, or 0.8 mm, etc., and the specific values ​​between the above values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0017] Furthermore, the number-average molecular weight of the compatibilizer A is 5000–10000, for example, but not limited to, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, or 10000. The number-average molecular weight of the compatibilizer A can be determined by gel permeation chromatography (GPC) based on a polystyrene standard.

[0018] Furthermore, the melting point of the compatibilizer A is 130-140°C, for example, but not limited to, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139 or 140°C.

[0019] Furthermore, the compatibilizer A is maleic anhydride-grafted polypropylene.

[0020] Furthermore, the melt flow rate of the polypropylene resin A, measured according to GB / T 3682.1-2018 standard at 230℃ and a load of 2.16 kg, is 60–150 g / 10 min. Specifically, it can be 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, or 150 g / 10 min, etc.

[0021] Furthermore, the melt flow rate of the polypropylene resin A, as determined by GB / T 3682.1-2018 standard, is 80-120 g / 10 min at 230°C and 2.16 kg load.

[0022] Furthermore, the halogen-free flame-retardant prepreg layer also includes 0.3 to 1 part of additives.

[0023] Furthermore, the additives include one or more of antioxidants, lubricants, weathering agents, or colorants.

[0024] The present invention also provides a method for preparing the above-mentioned halogen-free flame-retardant prepreg layer, comprising the following steps:

[0025] The components other than the glass fiber cloth in the halogen-free flame-retardant prepreg are mixed to obtain the prepreg. The glass fiber cloth is impregnated with the prepreg, rolled, baked, coated, and wound to obtain the halogen-free flame-retardant prepreg.

[0026] Specifically, the glass fiber cloth impregnation prepreg is applied to the surface of the glass fiber cloth at a temperature of 220-230°C, and double-sided impregnation is achieved through a coating process. The distribution of the adhesive solution is monitored in real time using an infrared sensor, and the spraying volume and conveying speed are dynamically adjusted to ensure the uniformity of the impregnation process.

[0027] The present invention also provides a polypropylene composite material, comprising an ablation-resistant polypropylene composition and the above-mentioned halogen-free flame-retardant prepreg layer; the thickness of the polypropylene composite material is ≤1.8mm.

[0028] It should be noted that the thickness of the polypropylene composite material is ≤1.8mm, for example, but not limited to ≤1.8mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm, 1.2mm, 1.1mm or 1mm, and the specific values ​​between the above values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0029] Furthermore, the thickness of the polypropylene composite material is ≤1.5mm.

[0030] In some preferred embodiments, the ablation-resistant polypropylene composition layer comprises the following components in parts by weight:

[0031]

[0032] Furthermore, the melt flow rate of the polypropylene resin B, as determined according to GB / T 3682.1-2018 standard, is 20–50 g / 10 min at 230°C and a load of 2.16 kg. Specifically, it can be 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, or 50 g / 10 min, etc.

[0033] Furthermore, the melt flow rate of the polypropylene resin B, as determined by GB / T 3682.1-2018 standard, is 25-40 g / 10 min at 230°C and 2.16 kg load.

[0034] Furthermore, the glass fiber is chopped glass fiber. By employing the ablation-resistant polypropylene composition layer and halogen-free flame-retardant prepreg layer of this invention, good ablation resistance and drop ball impact resistance can be achieved using chopped glass fiber.

[0035] Specifically, the average diameter of the chopped glass fibers is 10–15 μm, and the average length is 3–6 mm.

[0036] Furthermore, the compatibilizer B comprises maleic anhydride-grafted polyolefin.

[0037] Furthermore, the compatibilizer B is a maleic anhydride-grafted ethylene-octene copolymer.

[0038] Furthermore, the piperazine salt includes one or more of piperazine phosphate, piperazine pyrophosphate, or piperazine polyphosphate.

[0039] Furthermore, the melamine salt includes one or more of melamine phosphate, melamine pyrophosphate, or melamine polyphosphate.

[0040] The flame retardant content in the ablation-resistant polypropylene composition layer is not less than 20 wt%, for example, but not limited to, not less than 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, or 40 wt%, etc., and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the specific values ​​included in the range will not be exhaustively listed in this invention.

[0041] Furthermore, the flame retardant includes piperazine salts and melamine salts.

[0042] Furthermore, the synergistic flame retardant in the prepreg and ablation-resistant polypropylene composition layer includes one or more of zinc oxide, magnesium oxide, aluminum oxide, lanthanum oxide, or silicon dioxide.

[0043] Furthermore, the ablation-resistant polypropylene composition layer also includes 1 to 3 parts of flux.

[0044] Furthermore, the flux includes one or more of ammonium borate, zinc borate, boron frit, low-melting-point glass powder, nano-sepiolite, or montmorillonite.

[0045] Specifically, the flux D50 has a particle size of 6–10 μm.

[0046] Furthermore, the ablation-resistant polypropylene composition layer also includes 0.3 to 1 part of additives.

[0047] Furthermore, the additives include one or more of antioxidants, lubricants, weathering agents, or colorants.

[0048] In this invention, the antioxidant can be a commonly used antioxidant, such as, but not limited to, hindered phenolic antioxidants and / or phosphite antioxidants.

[0049] The hindered phenolic antioxidants include pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate (antioxidant 3114), vinylbis(oxyvinyl)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate] (Irganox 245), 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylic acid]-1,1-dimethyl}-2,4,8,10-tetraoxaspirocycloundecane (ADK AO-80), N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), and 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1098). One or more of 259) or β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate n-octadecyl ester (Irganox 1076).

[0050] The phosphite antioxidant is one or more of tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite (PEP-36), or 627A.

[0051] In this invention, commonly used lubricants may be selected, such as, but not limited to, one or more of vinyl bis-stearamide, polysiloxane, calcium stearate, magnesium stearate, zinc stearate, PE wax, or PP wax.

[0052] Commonly used weathering agents can be selected in this invention, such as, but not limited to, hindered amine light stabilizers and benzotriazole ultraviolet absorbers.

[0053] Specifically, the hindered amine light stabilizer is at least one of the following: bis-2,2,6,6-tetramethylpiperidinol sebacate, N,N'-bis-(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine, and a polymer of 2,4,6-trichloro-1,3,5-triazine.

[0054] Specifically, the benzotriazole ultraviolet absorber is one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), 2-(2'-hydroxy-3',5'-bis(a,a-dimethylbenzyl)phenyl)benzotriazole (UV-234), and 2-(-hydroxy-3-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole (UV-236).

[0055] The present invention also provides a method for preparing the above-mentioned polypropylene composite material, comprising the following steps:

[0056] S1. Mix all components in the ablation-resistant polypropylene composition layer evenly, and obtain injection molding granules by melt blending and extrusion granulation;

[0057] S2. Cut the halogen-free flame-retardant prepreg layer described in step S1 to the target product size, heat it and place it in the injection mold, melt the injection granules described in step S1 through the injection molding machine and inject them into the injection mold, and obtain the polypropylene composite material after pressure holding and cooling.

[0058] Specifically, the extrusion granulation described in step S1 is carried out in a twin-screw extruder.

[0059] Specifically, the feeding speed of the twin-screw extruder is 250-350 rpm.

[0060] Specifically, the temperature of the first zone of the twin-screw extruder is 150-160°C, the temperature of the second zone is 180-190°C, the temperature of the third to fifth zones is 210-230°C, and the temperature of the die is 200-210°C.

[0061] Specifically, the main motor speed of the twin-screw extruder is 300-500 rpm.

[0062] Specifically, the heating time in step S2 is 10 to 20 minutes.

[0063] Specifically, the heating temperature in step S2 is 110–120°C.

[0064] This invention also protects the use of the above-mentioned polypropylene composite material in the manufacture of household goods, electronic components, household appliances, motor vehicle parts, and vehicle body parts. In particular, the above-mentioned polypropylene composite material can be used to manufacture parts with good thin-wall ablation resistance and toughness. Especially, its application in the manufacture of electronic and electrical appliance housing materials is particularly suitable for energy storage battery pack covers, power battery lithium battery covers, electrical circuit board protection boxes, and new energy vehicle battery covers.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] This invention provides a halogen-free flame-retardant prepreg and a polypropylene composite material comprising the same. The halogen-free flame-retardant prepreg comprises glass fiber cloth and prepreg, wherein the thickness of the glass fiber cloth in the prepreg is 0.2–0.4 mm and the basis weight is 150–450 g / m². 2 The thickness of the halogen-free flame-retardant prepreg layer is 0.3-0.8 mm, and the polypropylene composite material includes an ablation-resistant polypropylene composition layer and a halogen-free flame-retardant prepreg layer; the thickness of the polypropylene composite material is ≤1.8 mm, and the polypropylene composite material obtained by in-mold secondary injection molding has good ablation resistance and drop ball impact resistance, and also has good self-supporting properties. Detailed Implementation

[0067] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0068] 1. Raw materials used in each embodiment and comparative example:

[0069] Polypropylene resin:

[0070] Polypropylene resin A: Copolymer polypropylene, PP K7100, with a melt flow rate of 110 g / 10 min at 230℃ and 2.16 kg load, tested according to ISO 1133-1:2022 standard, purchased from Sinopec Yanshan Petrochemical.

[0071] Polypropylene resin B: Copolymer polypropylene, PP EP548R, with a melt flow rate of 28 g / 10 min at 230℃ and 2.16 kg load, tested according to ISO 1133-1:2022 standard, purchased from CNOOC Shell Petrochemicals Co., Ltd.

[0072] Piperazine salt: Piperazine pyrophosphate, JNP-2, purchased from Sichuan Fine Chemical Research and Design Institute;

[0073] Melamine salt: melamine polyphosphate, Melapur 200-70, purchased from BASF AG;

[0074] Synergistic flame retardant: silica, XFI05, purchased from Xianfeng Nanomaterials Technology Co., Ltd.

[0075] Flux: Nano sepiolite, CALY 20, purchased from Torsa Group, Spain;

[0076] Fiberglass cloth:

[0077] Fiberglass cloth 1: EWR200-100, thickness: 0.2mm, weight: 210g / m² 2 Purchased from Sichuan Fiberglass Group Co., Ltd.

[0078] Fiberglass cloth 2: EWR300-100, thickness: 0.3mm, weight: 290g / m² 2 Purchased from Sichuan Fiberglass Group Co., Ltd.

[0079] Fiberglass cloth 3: EWR400-100, thickness: 0.4mm, weight: 420g / m² 2 Purchased from Sichuan Fiberglass Group Co., Ltd.

[0080] Fiberglass cloth 4: EWR100-100, thickness: 0.1mm, weight: 120g / m² 2 Purchased from Sichuan Fiberglass Group Co., Ltd.

[0081] Fiberglass: Chopped fiberglass, ECS13-4.5-508A, purchased from Jushi Group Co., Ltd.;

[0082] Compatibilizer A: Maleic anhydride-grafted polypropylene, UMEX 100TS, number average molecular weight of 9000, melting point of 136℃, purchased from Sanyo Chemical Industry Co., Ltd.

[0083] Compatibilizer B: Ethylene-octene copolymer grafted with maleic anhydride, DuPont TM N493, purchased from DuPont;

[0084] Additives:

[0085] Antioxidants: A compound of hindered phenolic antioxidant (Irganox 1010) and phosphite antioxidant (Irganox 168) in a mass ratio of 1:2, both of which are commercially available;

[0086] Lubricant: EBS B50, commercially available;

[0087] It should be noted that the same raw materials used in the parallel experiments of the embodiments and comparative examples in this invention all come from the same source.

[0088] 2. Parameter Measurement

[0089] (1) Determination of fiberglass cloth thickness: According to ISO 5084, a calibrated thickness gauge (25mm probe, 1kPa pressure) was used. The samples were conditioned at 23±2℃ and 50±5%RH for 24 hours, and 5 defect-free fiberglass cloth samples with an area of ​​100*100mm were cut. After calibration, the samples were placed flat, and the probe was slowly pressed. Three points were measured for each sample (avoiding nodes), and the stable values ​​were recorded. The overall mean was calculated.

[0090] (2) Measurement of the basis weight of fiberglass cloth: According to ISO 3801, a calibrated precision balance (accuracy 0.001g) and a 100cm calibrator were used. 2 Standard template. The samples were conditioned at 23±2℃ and 50±5%RH for 24 hours, and five defect-free samples were cut, avoiding the edges of the fabric roll. After precise cutting, dust was removed, and the weight (g / m³) was calculated. 2 = mass / area), example: 100cm 2 1.2g of sample corresponds to 120g / m 2 The results are taken as the average.

[0091] (3) Determination of the thickness of the halogen-free flame-retardant prepreg: According to ISO 5084, a calibrated thickness gauge (25mm probe, 1kPa pressure) was used. The samples were conditioned at 23±2℃ and 50±5%RH for 24 hours, and 5 defect-free halogen-free flame-retardant prepreg samples with an area of ​​100*100mm were cut. After calibration, the samples were placed flat, and the probe was slowly pressed. Three points were measured for each sample (avoiding nodes), and the stable values ​​were recorded. The overall mean was calculated.

[0092] (4) Thickness determination of polypropylene composite materials: A digital thickness gauge (for rigid materials) was used according to ISO 14129:1997. The samples were conditioned at 23±2℃ and 50±5%RH for 24 hours. Five defect-free samples (≥50×50mm) were cut, cleaned, and the instrument calibrated. The probe pressure for rigid materials was ≤10kPa, and for soft materials, the probe was increased to 30mm and the pressure reduced to ≤5kPa. Three to five points were measured on each sample (avoiding fiber-rich areas). The average value was calculated.

[0093] 3. Each halogen-free flame-retardant prepreg layer is prepared according to the formulations in Tables 1-2 using the following methods, including the following steps:

[0094] The components of the halogen-free flame-retardant prepreg layer, excluding the fiberglass cloth, are mixed using a high-speed mixer to obtain the prepreg. The fiberglass cloth is then impregnated with the prepreg (the prepreg is applied to the surface of the fiberglass cloth at a temperature of 220–230°C, and double-sided impregnation is achieved through a coating process. The distribution of the adhesive is monitored in real time using an infrared sensor, and the spraying amount and conveying speed are dynamically adjusted to ensure the uniformity of the impregnation process), rolled, baked, coated, and wound to obtain the halogen-free flame-retardant prepreg layer. The thickness of the halogen-free flame-retardant prepreg layer is adjusted by changing the amount of prepreg impregnated on the surface of the fiberglass cloth.

[0095] Table 1 Prepreg Formulation (Unit: Parts by Weight) Table 2. Halogen-free flame-retardant prepreg formulation

[0096]

[0097] 4. The polypropylene composite materials described in the various embodiments and comparative examples were prepared according to the formulations in Tables 3-5 by the following method, including the following steps:

[0098] S1. The components of the ablation-resistant polypropylene composition layer are mixed in a high-speed mixer for 1-3 minutes until homogeneous according to the formulation in Table 3. The mixture is then melt-blended and extruded using a twin-screw extruder to obtain injection molding granules. The feeding speed of the twin-screw extruder is 250-350 rpm, the temperature of the first zone of the twin-screw extruder is 150-160℃, the temperature of the second zone is 180-190℃, the temperature of the third to fifth zones is 210-230℃, and the temperature of the die is 200-210℃. The main motor speed of the twin-screw extruder is 300-500 rpm.

[0099] S2. Cut the halogen-free flame-retardant prepreg layer from the preparation example to the product size: 500mm*500mm. After heating at 110-120℃ for 10-20 minutes, place it into the injection mold. Melt the injection granules described in step S1 through an injection molding machine and inject them into the injection mold. After holding pressure and cooling, a polypropylene composite material is obtained. The thickness of the polypropylene composite material is adjusted by adjusting the injection volume of the mold and the ablation-resistant polypropylene composition.

[0100] 5. Performance Testing:

[0101] (1) Test of ablation resistance: 100mm*100mm square plates were cut from the polypropylene composite materials prepared in each example and comparative example. According to the test method of ablation materials in GJB323A-96, the oxy-acetylene flame was vertically applied to the ablation-resistant polypropylene composite layer of the square plate. The temperature of the oxy-acetylene flame was as high as 1300℃. The material was burned through or ablated for 600s. The degree of deformation and the time of burning through the polypropylene composite material were observed during the combustion process.

[0102] (2) Falling ball impact performance test: The polypropylene composite materials prepared in each example and comparative example were tested according to GB9639.1-2008 standard. The sample size was a square plate of 100mm*100mm. A steel ball of 535g mass was dropped from different heights to the center of the square plate. Each height required three tests. The sample that did not break after three tests was recorded as the falling ball impact fracture height.

[0103] (3) Back side temperature test: Cut 100mm*100mm square plates from the polypropylene composite materials prepared in each example and comparative example. According to the GJB323A-96 test method for ablation materials, the oxy-acetylene flame is vertically applied to the square plate until the square plate can no longer hold itself. Then, the temperature of the back side (the side away from the flame) of the square plate is tested using a FLUKE imaging test device.

[0104] (4) Flame retardant performance test: The polypropylene composite materials prepared in each example and comparative example were subjected to vertical burning according to UL94-2023.

[0105] Table 3 Formulation of ablation-resistant polypropylene composition layer (unit: parts by weight)

[0106] Preparation Example A B C D Polypropylene resin B 60.5 46.5 68.5 33.5 Piperazine salt 17 20 15 35 melamine salts 9 10 10 5 Synergistic flame retardants 1 1 0.5 1.5 Flux / / 1 3 Fiberglass 10 20 8 25 Compatibilizer B 2 2 1 5 antioxidants 0.3 0.3 / 0.3 lubricant 0.2 0.2 / 0.2

[0107] Table 4 Formulations and properties of polypropylene composites in Examples 1-8

[0108] Example 1 2 3 4 5 6 7 8 Halogen-free flame-retardant prepreg 1 2 3 4 5 6 7 8 ablation-resistant polypropylene composition layer A A A A A A A A Thickness (mm) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Flame retardant rating V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 Impact fracture height of falling ball (m) 3.5 2.7 2.3 2.5 2.5 3.4 2.8 2.3 Backside temperature (°C) 158 165 175 166 165 158 166 175 Burn-through time (s) 600 600 600 600 600 600 600 600 Degree of deformation (mm) 1.8 2.0 2.3 1.2 1.9 1.8 2.1 2.1

[0109] Table 5. Formulations and properties of polypropylene composites in Examples 9-14 and Comparative Examples 1-3.

[0110]

[0111]

[0112] The polypropylene composite materials prepared in the various embodiments of the present invention have good ablation resistance and falling ball impact resistance, good self-support (burn-through time and deformation degree), the burn-through time can reach 600s, the deformation degree does not exceed 2.5mm, the temperature on the back side of the combustion does not exceed 180℃, and the falling ball impact height is not less than 2m.

[0113] As can be seen from Comparative Examples 1 and 2, if the thickness of the glass fiber cloth in the halogen-free flame-retardant prepreg is too low, the polypropylene composite material produced will have poor performance and will be easily burned through.

[0114] As can be seen from Comparative Example 3, if the thickness of the halogen-free flame-retardant prepreg is too high, the ablation resistance of the resulting polypropylene composite material decreases, and it is easily burned through.

[0115] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A polypropylene composite material, characterized in that, The product comprises an ablation-resistant polypropylene composite layer and a halogen-free flame-retardant prepreg layer; the thickness of the polypropylene composite material is ≤1.8mm; the halogen-free flame-retardant prepreg layer comprises fiberglass cloth and prepreg, wherein the thickness of the fiberglass cloth in the halogen-free flame-retardant prepreg layer is 0.2~0.4mm, and the basis weight is 150~450g / m². 2 The thickness of the halogen-free flame-retardant prepreg layer is 0.3~0.8mm; The prepreg comprises the following components in parts by weight: 20-30 parts of polypropylene resin A; Piperazine salt 10-20 parts; 3-10 parts of melamine salt; 0.2-0.6 parts of synergistic flame retardant; Compatibilizer A: 0.8-1.2 parts; The ablation-resistant polypropylene composition layer comprises the following components in parts by weight: 30-70 parts of polypropylene resin B; Piperazine salt 15-35 parts; 5-12 parts of melamine salt; 0.5 to 2 parts of synergistic flame retardant; 8-25 parts glass fiber; Compatibilizer B1 ~ 5 parts.

2. The polypropylene composite material according to claim 1, characterized in that, The total content of piperazine salt and melamine salt in the prepreg is not less than 28 wt%.

3. The polypropylene composite material according to claim 1, characterized in that, The total content of piperazine salt and melamine salt in the prepreg is 33~55wt%.

4. The polypropylene composite material according to claim 1, characterized in that, Satisfy at least one of the following two conditions: (a) The number average molecular weight of the compatibilizer A is 5000~10000; the melting point is 130~140℃; (b) The melt flow rate of the polypropylene resin A at 230°C and 2.16 kg load is 60~150 g / 10 min.

5. The polypropylene composite material according to claim 1, characterized in that, The compatibilizer A is maleic anhydride-grafted polypropylene.

6. The polypropylene composite material according to claim 1, characterized in that, Satisfy at least one of the following two conditions: (a) The compatibilizer B comprises maleic anhydride-grafted polyolefin; (b) The melt flow rate of the polypropylene resin B at 230°C and 2.16 kg load is 20~50 g / 10 min.

7. The polypropylene composite material according to claim 1, characterized in that, The compatibilizer B is a maleic anhydride-grafted ethylene-octene copolymer.

8. A method for preparing the polypropylene composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Mix all components in the ablation-resistant polypropylene composition layer evenly, and obtain injection molding granules by melt blending and extrusion granulation; S2. Cut the halogen-free flame-retardant prepreg to the target product size, heat it and place it in the injection mold, inject the injection granules described in step S1 into the injection mold, and obtain the polypropylene composite material after pressure holding and cooling.

9. The preparation method according to claim 8, characterized in that, The method for preparing the halogen-free prepreg layer includes the following steps: The components other than the glass fiber cloth in the halogen-free flame-retardant prepreg are mixed to obtain the prepreg. The glass fiber cloth is impregnated with the prepreg, rolled, baked, coated, and wound to obtain the halogen-free flame-retardant prepreg.

10. The application of the polypropylene composite material according to any one of claims 1 to 7 in the preparation of energy storage battery pack power battery lithium battery cover, electrical circuit board protection box, and new energy vehicle battery cover.

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