Flame-retardant PP material with high strength and high modulus and preparation method thereof

Abstract

The invention provides a flame-retardant PP material with high strength and high modulus and a preparation method thereof. The flame-retardant PP material comprises the following raw materials in percentage by weight: 30-60% of polypropylene resin; 20 to 30% of a flame retardant; 20 to 30% of short glass fiber; 5-10% of a filling material; 5-10% of a compatilizer; and 2-3 wt% of other auxiliary agents. By compounding the piperazine halogen-free flame retardant, the glass fiber and the inorganic mineral powder, the tensile strength of the obtained polypropylene composite material reaches 69-75 MPa, the bending modulus reaches 5000-5400 MPa, and the tensile strength and the bending modulus are higher than general requirements of new energy battery materials; the flame retardant grade can reach 1.5 V0 of UL94, and the flame retardant grade requirements of most new energy batteries are met.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a flame-retardant PP material with high strength and high modulus and a preparation method thereof. Background Art

[0002] New energy battery ablation-resistant materials are generally thermosetting plastics (phenolic resin) or engineering plastics, which have good heat resistance and excellent structural steel, but the cost is high; now there are more and more general reinforced plastics to replace them, glass fiber reinforced polypropylene is one of them, but due to the short length of the short chopped fiber, the carbon layer formed in the entire polypropylene resin in the ablation experiment cannot play a good skeleton support role, so the carbon layer formed by the combustion of the flame retardant is very easy to collapse and cause the material to tear and penetrate. Therefore, improving the ablation resistance of the material can increase the value of the material and provide consumers with better safety.

[0003] CN109370043B discloses a low-cost short glass fiber reinforced halogen-free flame-retardant polypropylene material that can pass UL94-5VA and its preparation method. This short glass fiber reinforced halogen-free flame-retardant polypropylene material is composed of the following raw materials by mass: 40-70 parts of polypropylene; 5-30 parts of chopped glass fibers; 24-35 parts of PN expansion flame retardant; 0.3-1 parts of flame retardant synergist; 2-10 parts of compatibilizer; 0.3-0.5 parts of lubricant; 0.2-0.4 parts of antioxidant; 0.1-0.2 parts of emulsion anti-dripping agent. However, the material can only meet the UL94-5VA standard, but cannot achieve the ablation resistance standard of not burning through at 1000°C for 10 minutes.

[0004] CN117586582A discloses a halogen-free weather-resistant flame-retardant ablation-resistant polypropylene composite material and its preparation method. According to mass percentage, the ablation-resistant polypropylene composite material includes 6.2-37.8% polypropylene, 5-10% short glass fiber, 30-40% long glass fiber reinforced polypropylene, 5-10% ablation-resistant filler, 5-10% focused piperazine phosphate flame retardant, 5-10% triazine carbonizing agent, 3-5% dicyandiamide flame retardant, 3-5% compatibilizer, 0.2-0.8% weathering agent and 1-3% auxiliary agent. However, the defect of this technology is that the composite material obtained by compounding the short glass fiber halogen-free flame-retardant polypropylene masterbatch produced by twin-screw extrusion granulation and the long glass fiber reinforced polypropylene has a cumbersome processing process, and the composite material has a high filling amount, which is not conducive to lightweight industrial use.

[0005] CN115505207A provides a short glass fiber reinforced flame retardant polypropylene material, application and preparation method. The short glass fiber reinforced flame retardant polypropylene material is made of the following raw materials in parts by weight: 50-65 parts of polypropylene resin, 20-25 parts of short glass fiber, 3-5 parts of compatibilizer, 8-12 parts of titanium dioxide, 3-5 parts of flame retardant, 0.01-0.03 parts of carbon black, 0.3-0.6 parts of antioxidant, 0.3-0.8 parts of light stabilizer, 0.2-0.5 parts of lubricant and 0.2-0.5 parts of paraffin oil. However, this technology can only reach UL94-V0 level, and the glass fiber is mainly fed, the mechanical properties are greatly lost, the physical properties are poor and it does not have ablation resistance.

[0006] Normally, new energy battery materials are required to have good flame retardant properties, and as supporting structural parts, they must also have high rigidity and toughness. In order to increase the safety of consumers, the new energy battery cover plates of mid-to-high-end cars are also required to pass the ablation resistance test to ensure that users have enough time to escape when the battery spontaneously ignites out of control. Normally, due to the short length of the short glass fiber used in short glass fiber polypropylene materials, it is unable to play a good skeleton role, resulting in poor ablation resistance. Therefore, how to prepare a polypropylene composite material that has high strength and high modulus, excellent flame retardant properties and good ablation resistance is a problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the problems of the prior art, the present invention provides a high-strength and high-modulus flame-retardant PP material with excellent flame retardant properties and good ablation resistance. The flame-retardant PP material is compounded with piperazine halogen-free flame retardant, glass fiber and inorganic mineral powder to obtain a polypropylene composite material with a tensile strength of 69-75MPa and a bending modulus of 5000-5400MPa, which are higher than the general requirements of new energy battery materials; its flame retardant grade can reach UL94 1.5V 0 , meeting the flame retardant grade requirements of most new energy batteries.

[0008] The technical solution of the present invention is as follows: The present invention provides a flame-retardant PP material with high strength and high modulus, wherein the flame-retardant PP material comprises the following raw materials in percentage by mass: Polypropylene resin: 30-60%; Flame retardant: 20-30%; Short glass fiber: 20-30%; Filling material: 5-10%; Compatibilizer: 5-10%; Other additives: 2-3 wt%; The flame retardant PP material has a tensile strength of 69-75 MPa and a flexural modulus of 5000-5400 MPa.

[0009] Furthermore, the polypropylene resin has a melt index of 30-110 g / 10 min at 230° C. and 2.16 kg.

[0010] Further preferably, the melt index of the polypropylene resin at 230° C. and 2.16 kg is 30-80 g / 10 min.

[0011] Furthermore, the polypropylene resin is any one of homopolypropylene and copolymer polypropylene, or a combination of the two.

[0012] Furthermore, the polypropylene resin includes a combination of homopolymer polypropylene 800 powder, copolymer ultra-high melt polypropylene 648V and copolymer polypropylene 9829H, with a mass ratio of 15:10:9.

[0013] Furthermore, the flame retardant includes piperazine halogen-free flame retardant.

[0014] Furthermore, the short glass fiber is an alkali-free glass fiber. The length of the short glass fiber is 3-10 mm, more preferably 3-5 mm. The diameter of the short glass fiber is 7-17 μm, more preferably 7-13 μm.

[0015] Furthermore, the filling material includes sepiolite powder, which is hydrated magnesium silicate and is used to improve the carbonization rate and carbonization stability of the flame retardant.

[0016] Furthermore, the compatibilizer includes maleic anhydride grafted polypropylene, which is used to improve the compatibility between the polypropylene resin and the short glass fibers.

[0017] Furthermore, the flame retardant PP material also includes 5-10% by mass of a toughening agent.

[0018] Furthermore, the toughening agent includes polyolefin elastomer (POE), which plays a role in improving the toughness of the flame retardant PP material.

[0019] Furthermore, the other additives include at least one of an antioxidant, a lubricant, a light stabilizer, a glass fiber dispersant, a coupling agent and a color powder.

[0020] Furthermore, the antioxidant includes a primary antioxidant and an auxiliary antioxidant, the primary antioxidant includes any one of tris(2,4-di-tert-butyl)phenyl phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or a combination of two thereof, and the auxiliary antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0021] Furthermore, the antioxidant also includes boron oxide.

[0022] Furthermore, the lubricant includes at least one of erucamide, oleamide, stearic acid, magnesium stearate, calcium stearate, zinc stearate, silicone powder, polyethylene wax, and ethylene bisstearamide.

[0023] Furthermore, the light stabilizer includes a hindered amine light stabilizer, such as nickel dibutyl dithiocarbamate (UV3808).

[0024] Furthermore, the glass fiber dispersant includes TAF, that is, a reactive monomer containing a polar group reacts with ethylene bis fatty acid amide (EBS) to form a BAB type copolymer.

[0025] Furthermore, the coupling agent includes any one of a rare earth aluminate coupling agent and a white oil coupling agent.

[0026] Furthermore, the toner includes carbon black.

[0027] The present invention also provides a method for preparing the flame retardant PP material, comprising the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: After mixing all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, and obtain the flame-retardant PP material after the mixed material is extruded, cooled, and pelletized.

[0028] Furthermore, in step 2, the rotation speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0029] Furthermore, in step 2, the filler material, the coupling agent and the polypropylene resin are first mixed using a high-speed mixer, and then all the remaining raw materials except the glass fiber are mixed using a high-speed mixer for 3-5 minutes and then added from the main feed port of the twin-screw extruder.

[0030] The present invention has the following beneficial effects: 1. The present invention develops a short glass fiber polypropylene composite material with excellent flame retardant properties and good ablation resistance, which also has good structural rigidity, which can not only meet the requirements of high rigidity and high modulus of automotive structural parts, but also meet the flame retardant requirements of new energy battery materials.

[0031] 2. The present invention uses short glass fiber and halogen-free piperazine flame retardant in combination, and through a special process, the final PP flame retardant material has excellent flame retardant properties and can pass the 1.5V test of UL94. 0 and 5VA.

[0032] 3. The present invention uses a halogen-free flame retardant and sepiolite powder in combination, and while ensuring that the flame retardant requirements are met, the rapid carbonization of inorganic mineral powder is used to accelerate the carbonization rate and stability of the halogen-free flame retardant, so that the polypropylene material can quickly form a stable carbon layer under the high-temperature flame of methane combustion, and has good ablation resistance, solving the problem of collapse and tearing of short glass fiber flame-retardant polypropylene materials during ablation. The combined effect of the two greatly improves the carbonization rate and stability of the flame retardant, and can withstand 1000°C methane spray gun ablation for 10 minutes.

[0033] 4. The polypropylene composite material prepared by the composite use of piperazine halogen-free flame retardant (5001A), short glass fiber and inorganic mineral powder has high strength and high modulus, excellent flame retardant properties and good ablation resistance. Its tensile strength can be as high as 70MPa or more, and its bending modulus can be as high as 5200MPa or more, which are higher than the general requirements of new energy battery materials; its flame retardant grade can reach 1.5V of UL94. 0 , meeting the flame retardant grade requirements of most new energy batteries. Since the polypropylene composite material has high strength, high modulus, high toughness and good flame retardant and ablation resistance, it overcomes the shortcomings of thermosetting plastics that are non-recyclable, high cost and insufficient production capacity of engineering plastics, and high filling ratio, and can replace thermosetting plastics or engineering plastics as supporting structural parts of new energy vehicle batteries, greatly reducing costs and recycling, and has good production capacity. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0035] The raw materials used in the following examples and comparative examples are as follows: Polypropylene resins, including homopolymer polypropylene 800 powder, commercially available from Shandong Dongfang Hongye Chemical Co., Ltd.; copolymer ultra-high melt polypropylene 648V, commercially available from LyondellBasell Industries; and copolymer polypropylene 9829H, commercially available from China Petrochemical Corporation; Halogen-free piperazine flame retardant 5001A, commercially available from Guangdong Shunde Tongcheng New Materials Technology Co., Ltd.; Short glass fiber 438R, commercially available from Taishan Glass Fiber Co., Ltd.; Filling material: sepiolite powder, trade name ADINS® Clay 20; Compatibilizer: Polyacrylic acid grafted with maleic anhydride; Toughening agent: POE-8137, commercially available from Dow Chemical Company, USA; Antioxidant: S2225, commercially available from Tianjin Lianlong New Materials Co., Ltd.; Antioxidant: Boric oxide B203, commercially available from Tianjin Lianlong New Materials Co., Ltd.; Lubricant: silicone powder; Light stabilizer: UV3808; Glass fiber dispersant: TAF, commercially available from Qingdao Sino New Materials Co., Ltd.; Carbon forming agent: dipentaerythritol Coupling agent: white oil or rare earth aluminate coupling agent; Toner: Carbon Black M900.

[0036] Example 1 A flame retardant PP material with high strength and high modulus, comprising the following raw materials in percentage by mass: Polypropylene resin: 33%; including 14% homopolymer polypropylene 800 powder, 10% copolymer ultra-high melt polypropylene 648V and 9% copolymer polypropylene 9829H; Flame retardant: 30%; Short glass fiber: 20%; Filling material: 5%; Compatibilizer: 5%; Toughening agent: 5%; Antioxidant: 0.8%; Lubricant; 0.2% Light stabilizer: 0.3%; Glass fiber dispersant: 0.5%; Toner: 0.2%; The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: Mix all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, extrude, cool and pelletize the mixture to obtain a flame-retardant PP material, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0037] Example 2 A flame retardant PP material with high strength and high modulus, comprising the following raw materials in percentage by mass: Polypropylene resin: 32.8%; including 13.8% homopolymer polypropylene 800 powder, 10% copolymer ultra-high melt polypropylene 648V and 9% copolymer polypropylene 9829H; Flame retardant: 30%; Short glass fiber: 20%; Filling material: 5%; Compatibilizer: 5%; Toughening agent: 5%; Antioxidant: 0.8%; Lubricant; 0.2% Light stabilizer; 0.3%; Glass fiber dispersant: 0.5%; Coupling agent: 0.2%; Toner: 0.2%; The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: First, the filling material, coupling agent and polypropylene resin are mixed by a high-speed mixer, and then all the remaining raw materials except the glass fiber are mixed by a high-speed mixer for 3-5 minutes and added from the main feeding port of the twin-screw extruder, and the short glass fiber is added from the side feeding port of the twin-screw extruder. The mixed material is extruded, cooled and pelletized to obtain a flame-retardant PP material, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0038] Example 3 A flame retardant PP material with high strength and high modulus, comprising the following raw materials in percentage by mass: Polypropylene resin: 32.8%; including 15% homopolymer polypropylene 800 powder, 10% copolymer ultra-high melt polypropylene 648V and 9% copolymer polypropylene 9829H; Flame retardant: 30%; Short glass fiber: 20%; Filling material: 5%; Compatibilizer: 5%; Toughening agent: 5%; Antioxidant: 0.8%; Lubricant: 0.2%; Light stabilizer; 0.3%; Glass fiber dispersant: 0.5%; Coupling agent: 0.2%; Toner: 0.2%; The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: First, mix the filling material, coupling agent and polypropylene resin using a high-speed mixer, then mix all the remaining raw materials except the glass fiber using a high-speed mixer for 3-5 minutes and add them from the main feeding port of the twin-screw extruder, and add the short glass fiber from the side feeding port of the twin-screw extruder. After the mixture is extruded, cooled and pelletized, a flame-retardant PP material is obtained, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0039] Comparative Example 1 A flame retardant PP material, comprising raw materials in the mass percentages shown in Table 1: The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: Mix all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, extrude, cool and pelletize the mixture to obtain a flame-retardant PP material, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0040] Comparative Example 2 A flame retardant PP material, comprising raw materials in the mass percentages shown in Table 1: The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: Mix all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, extrude, cool and pelletize the mixture to obtain a flame-retardant PP material, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0041] Comparative Example 3 A flame retardant PP material, comprising raw materials in the mass percentages shown in Table 1: The preparation method comprises the following steps: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: Mix all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, extrude, cool and pelletize the mixture to obtain a flame-retardant PP material, wherein the speed of the twin-screw extruder is 350RPM and the melting temperature is 180-200°C.

[0042] Table 1 Raw material formula of Examples 1-3 and Comparative Examples 1-3

[0043] Table 2 Performance test of flame retardant PP materials of Examples 1-3 and Comparative Examples 1-3 performance Test Standards Test conditions unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 density ISO 1183 23℃ <![CDATA[g / cm 3 ]]> 1.223 1.222 1.238 1.262 1.258 1.260 Melt index ISO 1133 230℃ / 2.16kg g / 10min 22.2 13 16 15.6 19 19.5 Tensile Strength ISO 527-1 / 2 50mm / min MPa 65 73 77 71 69 70 Bending Strength ISO 178 2.0mm / min MPa 90 80 101 97 93 95 Flexural modulus ISO 178 2.0mm / min MPa 4315 4000 4800 5300 5000 5170 Simple supported beam notched impact strength ISO 179 23℃ <![CDATA[KJ / m 2 ]]> 9 11.5 9.2 9 9 9.1 Thermal deformation ISO-75-2 1.82MPa 120℃ ℃ 134 130 141 142 139 139 Flame retardant UL94 1.5mm s 5.6 3.1 8.6 0.8 Immortality 4.4 Ablation resistance 2.0mm 62 72 78 10min without wearing 10min without wearing 10min without wearing From the performance results in Table 2, we can see that: (1) Compared with Example 1, since no sepiolite powder is added to the raw materials of Comparative Example 1, the rapid carbonization effect of inorganic mineral powder is lacking, resulting in the inability to accelerate the carbonization rate and stability of the halogen-free flame retardant, so that the polypropylene material cannot quickly form a stable carbon layer under the high-temperature flame of methane combustion, resulting in poor flame retardancy and poor ablation resistance of the PP material.

[0044] (2) Compared with Example 1, in Comparative Example 2, a carbonizing agent was used in the raw materials instead of sepiolite powder. The flame retardancy and ablation resistance of the prepared PP material were poor, which indicated that other carbonizing agents such as dipentaerythritol had no effect on improving the flame retardancy and ablation resistance of the polypropylene resin system, and even led to the deterioration of the material properties.

[0045] (3) The role of the coupling agent is to premix and disperse the sepiolite powder with the granular polypropylene through the coupling agent, so that the sepiolite powder is pre-adhered to the polypropylene. Compared with Example 1, in Comparative Example 3, since sepiolite powder is added to the raw materials but no coupling agent is added, it is difficult to feed the raw materials during the preparation process. At the same time, the content of the halogen-free flame retardant is lower than that in Example 1, resulting in poor flame retardancy of the final PP material.

[0046] (4) No coupling agent was added to the raw materials of Example 1, while coupling agent was added to the raw materials of Examples 2 and 3. In terms of flame retardancy and ablation resistance, Example 1 is the best because the addition of coupling agent will affect the flame retardancy. However, the addition of coupling agent in Examples 2 and 3 will improve the feeding and optimize the process for easy production extrusion.

[0047] (5) It was unexpectedly found that the flexural modulus of the flame-retardant PP materials of Examples 1-3 was higher than that of Comparative Examples 1-3 due to the filling of sepiolite powder.

[0048] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A flame-retardant PP material with high strength and high modulus, characterized in that: The flame retardant PP material comprises the following raw materials in percentage by mass: Polypropylene resin: 30-60%; Flame retardant: 20-30%; Short glass fiber: 20-30%; Filling material: 5-10%; Compatibilizer: 5-10%; Other additives: 2-3 wt%; The flame retardant PP material has a tensile strength of 69-75 MPa and a flexural modulus of 5000-5400 MPa.

2. The flame retardant PP material according to claim 1, characterized in that: The polypropylene resin has a melt index of 30-110 g / 10 min at 230° C. and 2.16 kg.

3. The flame retardant PP material according to claim 1 or 2, characterized in that: The polypropylene resin is any one of homopolypropylene and copolymer polypropylene or a combination of the two.

4. The flame retardant PP material according to claim 3, characterized in that: The polypropylene resin includes a combination of homopolymer polypropylene 800 powder, copolymer ultra-high melting polypropylene 648V and copolymer polypropylene 9829H, with a mass ratio of 15:10:

9.

5. The flame retardant PP material according to claim 1 or 2, characterized in that: The flame retardant includes piperazine halogen-free flame retardant.

6. The flame retardant PP material according to claim 1 or 2, characterized in that: The short glass fibers have a length of 3-10 mm and a diameter of 7-17 μm.

7. The flame retardant PP material according to claim 1 or 2, characterized in that: The filling material includes sepiolite powder.

8. The flame retardant PP material according to claim 1 or 2, characterized in that: The flame retardant PP material also includes 5-10% by mass of a toughening agent.

9. A method for preparing the flame-retardant PP material according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: Weigh each raw material according to their respective mass percentages; Step 2: After mixing all the raw materials except the short glass fiber in a high-speed mixer for 3-5 minutes, add them from the main feeding port of the twin-screw extruder for shear melting, add the short glass fiber from the side feeding port of the twin-screw extruder, and obtain the flame-retardant PP material after the mixed material is extruded, cooled, and pelletized.

10. The preparation method according to claim 9, characterized in that: In step 2, the filler material, the coupling agent and the polypropylene resin are first mixed using a high-speed mixer, and then all the remaining raw materials except the glass fiber are mixed using a high-speed mixer for 3-5 minutes and then added from the main feed port of the twin-screw extruder.

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