Halogen-free flame-retardant ablation-resistant polypropylene composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials. The invention particularly relates to a halogen-free flame-retardant ablation-resistant polypropylene composite material as well as a preparation method and application thereof. The polypropylene composite material comprises 40-60% of flame-retardant modified master batch and 40-60% of long glass fiber reinforced polypropylene master batch, the flame-retardant modified master batch is prepared from the following raw materials in parts by weight: 24-44 parts of polypropylene resin, 5-15 parts of PPE resin, 2-5 parts of a compatilizer, 20-40 parts of piperazine substances, 10-20 parts of ammonium phosphate substances, 4-8 parts of surface modified superfine aluminum hydroxide and 0.3-1.5 parts of a processing aid. The content of the long glass fibers in the long glass fiber reinforced polypropylene master batch is 40-60wt%. PPE resin is introduced into a polypropylene halogen-free flame-retardant system, modified superfine aluminum hydroxide is compounded, halogen-free flame-retardant master batches and long glass fiber reinforced polypropylene master batches are uniformly compounded in proportion, and the halogen-free flame-retardant ablation-resistant material is obtained. While the high flame retardance of the material is maintained, the ablation resistance can be greatly improved, and the material is not burnt through after being continuously burnt for 10 minutes by a flame spray gun at the temperature of 1300 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to a halogen-free, flame-retardant, and ablation-resistant polypropylene composite material, a preparation method, and an application thereof. Background Art

[0002] In recent years, with the development of new energy vehicles, especially the iteration of power battery technology, more and more requirements have been put forward for the safety, lightweight and cost-effectiveness of battery packs. When the battery pack is subjected to extreme conditions such as external collision and puncture, it is necessary to reserve enough time to ensure that the owner can leave safely. Therefore, a safe and practical ablation-resistant material has become an unavoidable topic. Ablation-resistant materials usually refer to organic refractory polymer materials, which undergo chemical or physical changes such as decomposition, melting evaporation, sublimation, and carbonization during the combustion process to consume heat, prevent the spread of flames, and play a role in thermal protection. The polymer composite materials are mainly based on epoxy resin, phenolic resin, EPDM rubber and silicone rubber, and are mainly used in military industry, aerospace fields and wires and cables. With the development of the times, in recent years, the use of ablation-resistant materials has been explicitly required for the outer shell of new energy battery packs and air-conditioning electronic control boxes. The material requirements are as follows: 1. High flame retardant performance: the material has flame retardant UL94-V0 and 5VA grades; 2. Ablation resistance: the material preparation parts will not burn through and will not collapse or deform according to the GB.T31467.3-2015 test.

[0003] The existing technology has proposed some ablation-resistant material solutions from the perspective of halogen and halogen-free. For example, Patent 202111503847.8 proposed a bromine-based ablation-resistant flame-retardant polypropylene material and its preparation and application, and Patent 202111496655.9 proposed a halogen-free heat-insulating ablation-resistant flame-retardant polypropylene material and its preparation and application, but it involves more raw material systems, complex processes and high costs. The research on highly flame-retardant, ablation-resistant, and low smoke density polyolefin materials is a current hot topic, but in general, there are few types of halogen-free polyolefin materials that have high flame retardancy, ablation resistance, excellent thermal insulation, and low smoke density and are market-practical. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention aims to provide a halogen-free flame retardant and ablation-resistant polypropylene composite material, a preparation method and an application thereof. The halogen-free flame retardant and ablation-resistant polypropylene composite material is compounded with PPE resin in a halogen-free flame retardant system and compounded with long glass fiber masterbatch. Under the synergistic effect of the halogen-free flame retardant, the flame retardant, heat insulation and ablation resistance of the material are effectively improved, and the development steps are simple and the mechanical strength of the material is high.

[0005] A halogen-free flame-retardant and ablation-resistant polypropylene composite material, wherein the polypropylene composite material comprises, by mass percentage: 40-60% of flame-retardant modified masterbatch and 40-60% of long glass fiber reinforced polypropylene masterbatch;

[0006] The raw materials for preparing the flame retardant modified masterbatch include, by weight: 24-44 parts of polypropylene resin, 5-15 parts of PPE resin, 2-5 parts of compatibilizer, 20-40 parts of piperazine substances, 10-20 parts of amine phosphate substances, 4-8 parts of surface-modified ultrafine aluminum hydroxide, and 0.3-1.5 parts of processing aids;

[0007] The content of long glass fiber in the long glass fiber reinforced polypropylene masterbatch is 40-60wt%.

[0008] Furthermore, the polypropylene resin is one or more of homopolypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and propylene-1-butene random block.

[0009] Furthermore, the number average molecular weight distribution of the PPE resin is 20,000 to 60,000.

[0010] Furthermore, the compatibilizer is at least one of PP, POE, SEBS, and SEPS grafted with maleic anhydride.

[0011] Furthermore, the piperazine substance is one or more of piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate; the amine phosphate substance is one or more of melamine phosphate, melamine pyrophosphate, and melamine polyphosphate.

[0012] Furthermore, the preparation steps of the surface-modified ultrafine aluminum hydroxide are as follows: placing a coupling agent, melamine, a cross-linking agent and ultrafine aluminum hydroxide powder into a high-speed mixer, setting the temperature to 100° C., and mixing at high speed for 20 minutes to obtain surface-coated modified ultrafine aluminum hydroxide powder; the mass ratio of the coupling agent, melamine, cross-linking agent and ultrafine aluminum hydroxide is (2-5): (3-10): (0.1-0.5): (84.5-94.9).

[0013] Furthermore, the specific surface area of ​​the ultrafine aluminum hydroxide is 3 to 6 m 2 / g, the coupling agent is at least one of titanate and silane coupling agents; the cross-linking agent is at least one of dipropylbenzene peroxide, di-tert-butyl peroxide and tert-butyl perbenzoate; the processing aid is at least one of an antioxidant, a lubricant and a toner.

[0014] A method for preparing a halogen-free flame-retardant and ablation-resistant polypropylene composite material, the preparation method comprising the following steps:

[0015] S1. Polypropylene resin, PPE resin, compatibilizer, piperazine-type substance, phosphate amine salt-type substance, surface-modified ultrafine aluminum hydroxide, and processing aid are uniformly mixed in proportion, and melt-blended, granulated, and dried by a twin-screw extruder to obtain a flame-retardant modified masterbatch;

[0016] S2. Evenly blending the flame retardant modified masterbatch and the long glass fiber reinforced polypropylene masterbatch to obtain the halogen-free flame retardant and ablation-resistant polypropylene composite material.

[0017] Furthermore, the temperatures of the screws of the twin-screw extruder in step S1 from the feed port to the die are: 150-160°C in zone 1, 240-260°C in zone 2, 240-260°C in zone 3, 240-260°C in zone 4, 240-260°C in zone 5, 240-260°C in zone 6, 230-250°C in zone 7, 230-250°C in zone 8, 230-250°C in zone 9, and 240-260°C in zone 10; the feeding speed is 250-350rpm; the die head temperature is 230-250°C; the main engine speed is 300-500rpm / min; and the vacuum degree is lower than -0.1MPa.

[0018] The above-mentioned halogen-free flame-retardant and ablation-resistant polypropylene composite material is used as a raw material in automotive power battery pack housings and electrical control box products.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention prepares a halogen-free flame retardant and ablation-resistant polypropylene composite material, introduces PPE resin into the polypropylene halogen-free flame retardant system, and compounded with modified ultrafine aluminum hydroxide, and the halogen-free flame retardant masterbatch is evenly compounded with the long glass fiber reinforced polypropylene masterbatch in proportion to obtain a halogen-free flame retardant and ablation-resistant material; the halogen-free flame retardant and ablation-resistant material can achieve a significant improvement in ablation resistance while maintaining the high flame retardancy of the material, and can be continuously burned for 10 minutes by a 1300°C flame spray gun without burning through.

[0021] 2. The introduction of PPE resin and modified ultrafine aluminum hydroxide in the present invention makes the expanded carbon layer formed by the material during the burning process more dense and compact, which not only effectively prevents the transmission of flame temperature, but also makes the temperature on the back of the material flame lower than 150°C. It also has high strength and can withstand a certain external pressure. The carbon layer on the back will not be destroyed, thereby effectively isolating the spread of flame in some specific occasions. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Raw materials used in the embodiments and comparative examples:

[0024] Polypropylene, grade K7227H, Wuhan Petrochemical;

[0025] PPE resin, brand PPE LXR045, Nantong Xingchen Synthetic Materials Co., Ltd., number average molecular weight 40000-45000;

[0026] PPE resin, brand PPE LXR035, Nantong Xingchen Synthetic Materials Co., Ltd., number average molecular weight 25000-30000;

[0027] PP-g-MAH, brand CMG 5701, Jiayirong;

[0028] POE-g-MAH, brand CMG 5805-L, Jiayirong;

[0029] Melamine polyphosphate, MPP, Jiangsu Suli Fine Chemical Co., Ltd.;

[0030] Piperazine pyrophosphate, JNP-2, Sichuan Fine Chemical Research and Design Institute;

[0031] Ultrafine aluminum hydroxide, FR-205, Jinan Hongtu New Materials;

[0032] Titanate coupling agent, GR-201, Nanjing Herun coupling agent;

[0033] Melamine, Hubei Changao Pharmaceutical Co., Ltd.;

[0034] Long glass fiber reinforced polypropylene masterbatch, LFPP-1438 (glass fiber content 40wt%, particle length 12mm), Huitong New Materials Co., Ltd.

[0035] Long glass fiber reinforced polypropylene masterbatch, LFPP-14310 (glass fiber content 50wt%, particle length 12mm), Huitong New Materials Co., Ltd.

[0036] Long glass fiber reinforced polypropylene masterbatch, LFPP-14312 (glass fiber content 60wt%, particle length 12mm), Huitong New Materials Co., Ltd.

[0037] Other ingredients such as cross-linking agents, antioxidants, and lubricants are all conventional commercially available materials;

[0038] It should be noted that, for commercially available products, the same raw materials used in the following examples and comparative examples are from the same source.

[0039] Examples 1 to 5 Preparation of halogen-free flame-retardant and ablation-resistant polypropylene composite materials.

[0040] 1. Preparation of surface modified aluminum hydroxide;

[0041] The coupling agent, melamine, cross-linking agent and ultrafine aluminum hydroxide powder are mixed in a mass ratio of 3:6:0.3:90.7 and put into a high-speed mixer. The temperature is set at 100°C and mixed at high speed for 30 minutes. The surface-coated modified ultrafine aluminum hydroxide powder is obtained.

[0042] 2. Preparation of flame retardant modified masterbatch;

[0043] Polypropylene resin, PPE resin, compatibilizer, piperazine substance, amine phosphate substance, surface modified ultrafine aluminum hydroxide and processing aid are uniformly mixed in proportion, and a twin-screw extruder is used for melt blending, granulation and drying to obtain flame-retardant modified masterbatch; wherein the temperature of each section of the twin-screw extruder is as follows: the temperature of each section of the screw of the twin-screw extruder from the feeding port to the die is as follows: zone 1 160°C, zone 2 250°C, zone 3 250°C, zone 4 250°C, zone 5 250°C, zone 6 250°C, zone 7 240°C, zone 8 240°C, zone 9 240°C, zone 10 250°C; the feeding speed is 250-350rpm; the die temperature is 240°C.

[0044] The flame retardant masterbatch formulas of Examples 1 to 5 are shown in Table 1 below;

[0045] Table 1

[0046] Example 1 Example 2 Example 3 Example 4 Example 5 Polypropylene resin 29 37 44 34 24 PPE resin-LXR045 15 10 5 10 15 Compatibilizer PP-g-MAH 2 3 4 5 5 Piperazines 40 25 25 30 30 Ammonium phosphate substances 10 20 16 14 18 Surface modified ultrafine aluminum hydroxide 4 5 6 7 8 Antioxidant 1010 0.25 0.25 0.25 0.25 0.25 Antioxidant 168 0.25 0.25 0.25 0.25 0.25 Carbon Black 0.3 0.3 0.3 0.3 0.3 Lubricants 0.3 0.3 0.3 0.3 0.3

[0047] A method for preparing a halogen-free flame-retardant and ablation-resistant polypropylene composite material, the preparation method comprising the following steps:

[0048] S1, preparing flame retardant modified masterbatch;

[0049] S2. Evenly blending the flame retardant modified masterbatch and the long glass fiber reinforced polypropylene masterbatch to obtain the halogen-free flame retardant and ablation-resistant polypropylene composite material.

[0050] The specific formula is shown in Table 2.

[0051] Table 2

[0052]

[0053]

[0054] The preparation methods of the polypropylene modified materials of Comparative Examples 1 to 5 are as follows;

[0055] 1. Preparation of surface modified aluminum hydroxide;

[0056] The coupling agent, melamine, cross-linking agent and ultrafine aluminum hydroxide powder are mixed in a mass ratio of 3:6:0.3:90.7 and put into a high-speed mixer. The temperature is set at 100°C and mixed at high speed for 30 minutes. The surface-coated modified ultrafine aluminum hydroxide powder is obtained.

[0057] 2. Preparation of flame retardant modified masterbatch;

[0058] Polypropylene resin, PPE resin, compatibilizer, piperazine substance, amine phosphate substance, surface modified ultrafine aluminum hydroxide and processing aid are uniformly mixed in proportion, and a twin-screw extruder is used for melt blending, granulation and drying to obtain flame-retardant modified masterbatch; wherein the temperature of each section of the twin-screw extruder is as follows: the temperature of each section of the screw of the twin-screw extruder from the feeding port to the die is as follows: zone 1 160°C, zone 2 250°C, zone 3 250°C, zone 4 250°C, zone 5 250°C, zone 6 250°C, zone 7 240°C, zone 8 240°C, zone 9 240°C, zone 10 250°C; the feeding speed is 250-350rpm; the die temperature is 240°C.

[0059] The flame retardant modified masterbatch formulas of Comparative Examples 1 to 5 are as follows, see Table 3;

[0060] Table 3

[0061]

[0062]

[0063] A method for preparing a polypropylene modified material, the preparation method comprising the following steps:

[0064] S1, preparing flame retardant modified masterbatch;

[0065] S2. Evenly blending the flame retardant modified masterbatch and the long glass fiber reinforced polypropylene masterbatch to obtain the halogen-free flame retardant and ablation-resistant polypropylene composite material.

[0066] The specific formula is shown in Table 4.

[0067]

[0068] The halogen-free flame retardant and ablation-resistant polypropylene composite materials prepared in Examples 1 to 5 and the polypropylene modified materials prepared in Comparative Examples 1 to 5 were respectively tested for UL94 flame retardancy, continuous burning at 1300°C for 10 min, sample burn-through degree, back surface temperature, and carbon layer strength after combustion.

[0069] Performance test standards:

[0070] (1) Flame retardant grade test: According to UL94-2016, test specimen size: 125mm×12.5mm×2.0mm specimen

[0071] (2) Ablation resistance test: According to the GJB323A-96 ablation material test method, an oxygen-acetylene flame is vertically directed to a square plate with a length, width and thickness of 100 mm, 100 mm and 2.0 mm. The temperature of the oxygen-acetylene flame is as high as 1300°C. The material is ablated and the time it takes for the square plate to be burned through is recorded.

[0072] (3) Back surface temperature: According to the GJB323A-96 ablative material test method, an oxygen-acetylene flame is vertically directed onto a square plate with a length, width and thickness of 100 mm, 100 mm and 2.0 mm. When the square plate is unable to support itself, the back surface temperature of the square plate is tested using a FLUKE imaging test device.

[0073] (4) Test the strength of the carbon layer after ablation: Use a 250g iron ball to hit the back of the carbon layer vertically from different heights to see the lowest height of the iron ball when the carbon layer breaks.

[0074] The test results are shown in Table 5;

[0075] Table 5

[0076]

[0077] From the results in Table 5, it can be seen that the halogen-free flame retardant and ablation-resistant polypropylene composite materials prepared in Examples 1 to 5 of the present invention can achieve a significant improvement in the corrosion resistance of the material while maintaining the high flame retardancy of the polypropylene material, and achieve lower back temperature heat conduction and higher back carbon layer strength; achieve 1300°C ablation for 10 minutes without being burned through, and the back temperature of the material is as low as 136-157°C; the impact rupture height of the back carbon layer after burning reaches 250-300 mm.

[0078] However, for the polypropylene modified materials prepared in Comparative Examples 1 to 6, Comparative Example 1 cannot even reach the flame retardant V0 grade. This is because when the flame retardant content is insufficient, referring to Comparative Example 1, the lack of PPE resin fails to effectively provide flame retardant properties. PPE resin not only has certain flame retardant properties itself, but also can provide a carbon source for the combustion process and promote carbonization to block the transfer of fire sources in the system, thereby making the composite material have better flame retardancy; For Comparative Example 2, even if the system can reach V0 flame retardancy, referring to Example 2, since ultrafine aluminum hydroxide is not added, the burning process cannot effectively resist the transfer of heat sources, resulting in the sample being burned through; Comparative Example 3 can achieve V0 flame retardancy, and the sample is not burned through during the combustion process, but the strength of the carbon layer after burning is significantly reduced. Referring to Example 3, since the added ultrafine aluminum hydroxide is not surface modified, on the one hand, the ultrafine aluminum hydroxide fails to achieve good dispersion in the resin system, And cooperate to evenly form a dense carbon layer to block the fire source. On the other hand, the ultrafine aluminum hydroxide modified by melamine surface grafting, during the combustion process, the aluminum hydroxide decomposes and absorbs heat and the melamine is burned to carbonize at the same time, which not only blocks the transfer of the heat source, but also promotes the formation of a dense carbon layer to isolate the fire source and heat; Comparative Examples 4 and 5 show that for piperazine substances, ammonium phosphate substances and surface-modified ultrafine aluminum hydroxide, their content and ratio need to be finely controlled, otherwise the ideal effect cannot be achieved, and good ablation resistance cannot be achieved; Although Comparative Example 6 achieves flame retardant performance V0, and the burning process does not burn through, referring to Comparative Example 1, it can be seen that the back temperature and the carbon layer strength are reduced. This is because the molecular weight of the PPE resin added in Comparative Example 6 is lower than 35,000, and the molecular weight is relatively low, which is not conducive to carbonization during the burning process, thereby increasing the back temperature and decreasing the carbon layer strength.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A halogen-free flame-retardant and ablation-resistant polypropylene composite material, characterized in that: The polypropylene composite material comprises, by mass percentage, 40-60% of flame retardant modified masterbatch and 40-60% of long glass fiber reinforced polypropylene masterbatch; The raw materials for preparing the flame retardant modified masterbatch include, by weight: 24-44 parts of polypropylene resin, 5-15 parts of PPE resin, 2-5 parts of compatibilizer, 20-40 parts of piperazine substances, 10-20 parts of amine phosphate substances, 4-8 parts of surface-modified ultrafine aluminum hydroxide, and 0.3-1.5 parts of processing aids; The content of long glass fiber in the long glass fiber reinforced polypropylene masterbatch is 40-60wt%.

2. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 1, characterized in that: The polypropylene resin is one or more of homopolypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer and propylene-1-butene random block.

3. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 2, characterized in that: The number average molecular weight distribution of the PPE resin is above 35,000.

4. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 1, characterized in that: The compatibilizer is at least one of PP, POE, SEBS, and SEPS grafted maleic anhydride.

5. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 1, characterized in that: The piperazine substance is one or more of piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate; the amine phosphate substance is one or more of melamine phosphate, melamine pyrophosphate, and melamine polyphosphate.

6. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 1, characterized in that: The preparation steps of the surface-modified ultrafine aluminum hydroxide are as follows: placing a coupling agent, melamine, a cross-linking agent and ultrafine aluminum hydroxide powder into a high-speed mixer, setting the temperature to 100° C., and mixing at high speed for 20 minutes to obtain surface-coated modified ultrafine aluminum hydroxide powder; the mass ratio of the coupling agent, melamine, cross-linking agent and ultrafine aluminum hydroxide is (2-5): (3-10): (0.1-0.5): (84.5-94.9).

7. The halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 1, characterized in that: The specific surface area of ​​the ultrafine aluminum hydroxide is 3 to 6 m 2 / g, the coupling agent is at least one of titanate and silane coupling agents; the cross-linking agent is at least one of dipropylbenzene peroxide, di-tert-butyl peroxide and tert-butyl perbenzoate; the processing aid is at least one of an antioxidant, a lubricant and a toner.

8. A method for preparing a halogen-free flame-retardant and ablation-resistant polypropylene composite material, characterized in that: The preparation method comprises the following steps: S1. Polypropylene resin, PPE resin, compatibilizer, piperazine-type substance, phosphate amine salt-type substance, surface-modified ultrafine aluminum hydroxide, and processing aid are uniformly mixed in proportion, and melt-blended, granulated, and dried by a twin-screw extruder to obtain a flame-retardant modified masterbatch; S2. Evenly blending the flame retardant modified masterbatch and the long glass fiber reinforced polypropylene masterbatch to obtain the halogen-free flame retardant and ablation-resistant polypropylene composite material.

9. The method for preparing a halogen-free flame-retardant and ablation-resistant polypropylene composite material according to claim 8, characterized in that: The temperatures of the screws of the twin-screw extruder in step S1 from the feed port to the die are: 150-160°C for zone 1, 240-260°C for zone 2, 240-260°C for zone 3, 240-260°C for zone 4, 240-260°C for zone 5, 240-260°C for zone 6, 230-250°C for zone 7, 230-250°C for zone 8, 230-250°C for zone 9, and 240-260°C for zone 10; the feeding speed is 250-350rpm; the die head temperature is 230-250°C; the main engine speed is 300-500rpm / min; and the vacuum degree is lower than -0.1MPa.

10. Use of the halogen-free flame-retardant and ablation-resistant polypropylene composite material as claimed in any one of claims 1 to 7 as a raw material in automotive power battery pack housings and electrical control box products.

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