Polypropylene flame-retardant plastic, its preparation method and application

Abstract

The application discloses a kind of polypropylene flame-retardant plastic and its preparation method and application, it is related to high polymer material technical field.A kind of polypropylene flame-retardant plastic, by following mass parts of raw materials composition: polypropylene 70-80 parts, halogen-free flame retardant 15-25 parts, flame-retardant synergist 1-5 parts, toughening agent 5-15 parts, antioxidant 0.1-0.5 parts, lubricant 0.5-2 parts.The application adopts specific structure halogen-free flame retardant, collocates flame-retardant synergist, can form dense stable carbon layer on polypropylene matrix surface, effectively insulates heat and oxygen, inhibits combustible gas release, to significantly improve flame-retardant performance, reduce combustion spread speed, improve vertical combustion grade.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a flame-retardant polypropylene plastic, its preparation method, and its application. Background Technology

[0002] In the field of polymer materials, polypropylene, as a widely used plastic material, is widely applied in various industries due to its excellent mechanical properties, chemical corrosion resistance, and low cost. However, polypropylene itself is flammable, and its combustion produces a large amount of heat and harmful gases, which greatly limits its application in situations with strict fire resistance requirements.

[0003] Traditional flame retardant methods primarily rely on halogenated flame retardants. While these retardants effectively reduce the combustion rate of materials, they generate large amounts of smoke and toxic gases during combustion, polluting the environment and posing a serious threat to human health. With increasing environmental awareness, halogen-free flame retardant technology has gradually become a research and application hotspot. Halogen-free flame retardants do not release harmful gases during combustion, effectively reducing smoke production and improving the environmental performance and safety of materials. Furthermore, polypropylene materials face other challenges in practical applications. Their insufficient toughness can lead to easy breakage during use, especially at low temperatures where brittleness is more pronounced. Simultaneously, polypropylene is susceptible to thermo-oxidative aging during processing, resulting in a decline in material performance. Therefore, how to improve the flame retardancy of polypropylene while simultaneously maintaining its toughness and oxidation resistance is a pressing issue in the field of polymer materials.

[0004] In conclusion, developing a flame-retardant polypropylene plastic with good flame retardant properties, environmental friendliness and halogen-free characteristics, as well as excellent toughness and oxidation resistance, is of great practical significance for meeting the high requirements of modern industry for material performance. Summary of the Invention

[0005] The purpose of this invention is to address the problems of flammability of polypropylene materials, the environmental unfriendliness of traditional halogenated flame retardants, and insufficient material toughness in existing technologies, by providing a flame-retardant polypropylene plastic, its preparation method, and its applications. This plastic material not only possesses excellent halogen-free flame-retardant properties but also exhibits good toughness and resistance to thermo-oxidative aging, meeting the requirements of applications with high fire safety and environmental protection standards.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A flame-retardant polypropylene plastic is composed of the following raw materials in parts by weight: 70-80 parts polypropylene, 15-25 parts halogen-free flame retardant, 1-5 parts flame retardant synergist, 5-15 parts toughening agent, 0.1-0.5 parts antioxidant, and 0.5-2 parts lubricant.

[0008] The halogen-free flame retardant is a compound represented by Formula 1 below:

[0009] Formula 1: ;

[0010] In Formula 1, R1 is selected from any one of hydrogen, methoxy, ethyl, and propyl.

[0011] Furthermore, the polypropylene is homopolymer polypropylene with a melt index of 2-10 g / 10 min.

[0012] Furthermore, the halogen-free flame retardant is any one of the compounds shown in the following structures:

[0013] ;

[0014] .

[0015] Furthermore, the flame retardant synergist is at least one of nano-montmorillonite or zinc oxide.

[0016] Furthermore, the toughening agent is an ethylene-octene copolymer.

[0017] Furthermore, the antioxidant is a compound of antioxidant 1010 and antioxidant 168, with a mass ratio of 1:1.

[0018] Furthermore, the lubricant is a compound of butyl stearate and ethylene bis-stearamide, with a mass ratio of 1:1.

[0019] Furthermore, α-olefin-ethylene copolymer, vinyl elastomer, and high-performance polypropylene may also be added to the polypropylene flame-retardant plastic.

[0020] A method for preparing a flame-retardant polypropylene plastic includes the following steps:

[0021] S1. Place the polypropylene, halogen-free flame retardant, flame retardant synergist, toughening agent, antioxidant and lubricant in a drying oven at 60-80℃ and dry for 2-4 hours to remove moisture from the raw materials;

[0022] S2. Add the pretreated polypropylene and toughening agent to a high-speed mixer and mix for 5-8 minutes at a speed of 800-1200 r / min. Then add the pretreated halogen-free flame retardant, flame retardant synergist, antioxidant and lubricant, and continue mixing for 8-15 minutes until the materials are evenly mixed to obtain a premix.

[0023] S3. The premixed material is added to a twin-screw extruder, and the temperature of each section of the extruder is controlled as follows: feeding section 150-160℃, compression section 170-180℃, homogenization section 180-190℃, die head temperature 185-195℃, and screw speed 150-250r / min. After melting, shearing and mixing, the material is extruded from the die head to obtain an extruded melt.

[0024] S4. After the extruded melt is cooled to room temperature by water cooling, it is pelletized by a pelletizer and dried in a hot air circulating oven at 70-80℃ for 3-5 hours to remove surface moisture, thus obtaining a flame-retardant polypropylene plastic.

[0025] Furthermore, during the mixing process of the high-speed mixer in S2, cooling water is introduced through the jacket to control the temperature of the mixed materials to not exceed 50°C, so as to avoid the raw materials from melting and sticking due to excessive temperature.

[0026] Application of a flame-retardant polypropylene plastic in plastic running tracks.

[0027] This invention systematically solves the core technical problems of polypropylene's flammability, the environmental unfriendliness of traditional halogenated flame retardants, insufficient material toughness, and poor resistance to thermo-oxidative aging through precise proportioning and synergistic effects of various raw materials, combined with a scientific preparation process. Specifically, the halogen-free flame retardant with a specific structure promotes the rapid formation of a dense and stable char layer on the surface of the polypropylene matrix during heating and combustion, effectively isolating heat and oxygen and inhibiting the release of combustible gases, fundamentally reducing the combustion rate. Combined with nano-montmorillonite or zinc oxide-based flame retardant synergists, the synergistic effect of these two agents not only inhibits the spread of combustion through the char-forming flame retardant mechanism of ammonium polyphosphate, but also improves flame retardant efficiency through the dispersion and filling effect of the synergists, avoiding the environmental hazards of toxic gas release from the combustion of traditional halogenated flame retardants and achieving excellent halogen-free flame retardant performance. The use of ethylene-octene copolymer as a toughening agent forms a good compatibility system with homopolymer polypropylene, effectively compensating for the insufficient toughness of polypropylene itself. The material overcomes the low-temperature brittleness defect by enhancing its fracture resistance during use. The combination of antioxidants 1010 and 168 provides synergistic anti-aging effects, specifically inhibiting thermo-oxidative aging during polypropylene processing and use, thus delaying material performance degradation. Lubricants optimize material flowability during processing. Combined with raw material pretreatment drying, high-speed mixing and temperature control, and segmented temperature and speed regulation in twin-screw extrusion, this ensures uniform dispersion of flame retardants, toughening agents, antioxidants, and other components within the polypropylene matrix, preventing localized performance imbalances. Ultimately, this achieves a synergistic improvement in flame retardancy, environmental friendliness, toughness, and thermo-oxidative aging resistance, meeting the demands of applications requiring high fire safety and comprehensive performance.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. Significantly improved flame retardant performance: This invention uses a halogen-free flame retardant with a specific structure, combined with a flame retardant synergist, which can form a dense and stable char layer on the surface of the polypropylene matrix, effectively isolating heat and oxygen, inhibiting the release of combustible gases, thereby significantly improving flame retardant performance, reducing the rate of combustion spread, and improving the vertical combustion rating.

[0030] 2. Good mechanical properties are maintained: By selecting appropriate toughening agents, this invention can improve the flame retardant properties while effectively compensating for the lack of toughness of polypropylene itself, maintaining the tensile strength and other mechanical properties of the material, avoiding the deterioration of mechanical properties caused by flame retardant modification, and ensuring the stability of the mechanical properties of the material in practical applications.

[0031] 3. Excellent aging resistance: Through the compounding of antioxidants and scientific preparation process, this invention significantly improves the heat and oxygen aging resistance of polypropylene flame-retardant plastic, so that the material maintains stable performance during long-term use, has a high tensile strength retention rate after aging, and extends the service life of the material, meeting the application scenarios with high requirements for fire safety and comprehensive performance of the material. Attached Figure Description

[0032] Figure 1 This is the 1H-NMR spectrum of the halogen-free flame retardant 1 described in this invention. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Preparation Example 1

[0035] Preparation of halogen-free flame retardant 1:

[0036] first step:

[0037] ;

[0038] 3.18 g of compound 2 was dissolved in 60 mL of anhydrous tetrahydrofuran, and 6.64 g of triethylamine was added. The mixture was stirred until homogeneous. 5.00 g of compound 1 was slowly added dropwise using a syringe at room temperature, keeping the solution temperature stable during the addition. After the addition was complete, the reaction mixture was stirred at room temperature for 4 hours. After the reaction was complete, the reaction mixture was poured into water and extracted with ethyl acetate. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered to remove the drying agent, and the filtrate was concentrated on a rotary evaporator to obtain the crude product. The crude product was then eluted by silica gel column chromatography with a petroleum ether / ethyl acetate mixture as the eluent. The filtrate was concentrated to obtain 4.47 g of the intermediate. The MS [MS+1] of the intermediate was 275.

[0039] Step Two:

[0040] ;

[0041] 4.47 g of the intermediate was added to a round-bottom flask, followed by 100 mL of tetrahydrofuran. The mixture was stirred thoroughly, then 2.29 g of 1-hydroxybenzotriazole, 3.25 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 6.34 g of compound 3 were added sequentially. 5.90 g of N,N-diisopropylethylamine was slowly added dropwise, and the mixture was stirred at room temperature for 4 hours. After the reaction was complete, the mixture was poured into a saturated sodium bicarbonate aqueous solution and extracted with ethyl acetate. The organic layers were combined, washed with a saturated sodium chloride aqueous solution, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. This crude product was then subjected to silica gel column chromatography, eluted with a petroleum ether / ethyl acetate mixture, and the filtrate was concentrated to obtain 4.81 g of halogen-free flame retardant 1. The mass spectrometry (MS) [MS+1] of halogen-free flame retardant 1 was 895, and the NMR of halogen-free flame retardant 1 was as follows: Figure 1 As shown.

[0042] Preparation Examples 2-4

[0043] In Preparation Examples 2-4, halogen-free flame retardant 2-halogen-free flame retardant 4 were prepared sequentially, following the same preparation method as in Preparation Example 1, except that compound 2 was replaced, while the rest remained the same as in Preparation Example 1. See Table 1 for details.

[0044]

[0045] Example 1

[0046] Preparation of a flame-retardant polypropylene plastic:

[0047] a. Raw material weight parts:

[0048] Polypropylene: 75 parts, homopolymer polypropylene, melt index of 5 g / 10 min (230℃, 2.16 kg).

[0049] Halogen-free flame retardant: 20 parts, which is the halogen-free flame retardant 1 prepared in Preparation Example 1;

[0050] Flame retardant synergist: 3 parts, nano-montmorillonite;

[0051] Toughening agent: 10 parts, ethylene-octene copolymer, octene content 25%;

[0052] Antioxidant: 0.3 parts, which is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1;

[0053] Lubricant: 1.5 parts, which is a compound of butyl stearate and ethylene bis-stearamide in a mass ratio of 1:1.

[0054] b. Preparation method:

[0055] S1. Place the polypropylene, halogen-free flame retardant, flame retardant synergist, toughening agent, antioxidant and lubricant in a drying oven at 70°C for 3 hours to remove moisture from the raw materials;

[0056] S2. First, add the dried polypropylene and toughening agent to a high-speed mixer and mix for 6 minutes at 1000 r / min. Then, add the dried halogen-free flame retardant, flame retardant synergist, antioxidant and lubricant, and continue mixing for 10 minutes. During the mixing process, the temperature of the mixture is controlled to not exceed 50°C by passing cooling water through the jacket until the material is mixed evenly to obtain a premix.

[0057] S3. Add the obtained premix to a twin-screw extruder and control the temperature of each section of the extruder as follows: feeding section 155℃, compression section 175℃, homogenization section 185℃, die head temperature 190℃, screw speed 200 r / min. After melting, shearing and mixing, the material is extruded from the die head to obtain the extruded melt.

[0058] S4. After the extruded melt is cooled to room temperature by water cooling, it is pelletized by a pelletizer. Then, the pellets are placed in a hot air circulating oven at 75°C and dried for 4 hours to remove surface moisture, thus obtaining a flame-retardant polypropylene plastic.

[0059] Examples 2-4

[0060] The preparation of a polypropylene flame retardant plastic is carried out by referring to the preparation method of Example 1, except that the halogen-free flame retardant is replaced in sequence with the halogen-free flame retardant 2-halogen-free flame retardant 4 prepared in Preparation Examples 2-4, and other operations are the same as in Example 1.

[0061] Comparative Example 1

[0062] The preparation of a flame-retardant polypropylene plastic is carried out by referring to the preparation method of Example 1, except that the halogen-free flame retardant is replaced with ammonium polyphosphate, and other operations are the same as in Example 1.

[0063] Comparative Example 2

[0064] The preparation of a flame-retardant polypropylene plastic is carried out by referring to the preparation method of Example 1, except that the halogen-free flame retardant is replaced with aluminum hydroxide, and other operations are the same as in Example 1.

[0065] Comparative Example 3

[0066] The preparation of a flame-retardant polypropylene plastic is carried out according to the preparation method of Example 1, without adding the halogen-free flame retardant, and the other operations are the same as in Example 1.

[0067] Comparative Example 4

[0068] The preparation of a flame-retardant polypropylene plastic is carried out according to the preparation method of Example 1, without adding the flame retardant synergist, and the other operations are the same as in Example 1.

[0069] Performance testing

[0070] 1. Vertical flammability test: According to GB / T 2408-2021, the plastics prepared in the examples and comparative examples were made into 127mm×12.7mm×3.2mm specimens. The UL94 vertical flammability test mode was used to record the afterflame time, afterglow time and dripping situation to evaluate the flammability rating. The results are shown in Table 2.

[0071] 2. Mechanical property testing: In accordance with GB / T 1040.1-2018, the plastics prepared in the examples and comparative examples were made into 80mm×10mm×4mm specimens, and the tensile strength (MPa) of the specimens was tested. The results are shown in Table 2.

[0072] 3. Thermo-oxidative aging performance test: According to GB / T 7141-2021, the plastics prepared in the examples and comparative examples were made into 80mm×10mm×4mm specimens. The specimens were placed in a thermo-aging chamber and the aging conditions were set as follows: temperature 120℃, aging time 1000h. After aging, the specimens were taken out and cooled to room temperature. The tensile strength was measured according to the above mechanical property test method, and the tensile strength retention rate (%) was calculated. The results are shown in Table 2.

[0073] Table 2

[0074] flammability rating Tensile strength (MPa) Tensile strength retention rate after aging (%) Example 1 V-0 27.5 91.3 Example 2 V-0 26.8 90.7 Example 3 V-0 27.2 91.1 Example 4 V-0 26.6 90.9 Comparative Example 1 V-1 25.9 90.5 Comparative Example 2 V-2 24.7 90.2 Comparative Example 3 HB 28.2 90.1 Comparative Example 4 V-1 25.6 91.1

[0075] Table 2 shows that, compared with the comparative examples, the embodiments using the halogen-free flame-retardant system of this invention exhibit a significant overall improvement in flame-retardant performance, with a markedly higher vertical burning rating and effectively suppressed combustion spread rate, indicating higher flame-retardant efficiency. Regarding mechanical properties, the embodiments maintain excellent flame-retardant performance while also retaining good tensile properties, without significant mechanical degradation due to flame-retardant modification. Furthermore, after thermo-oxidative aging, the mechanical properties of each embodiment remained relatively stable, with minimal changes before and after aging, indicating that the flame-retardant system has minimal impact on the long-term performance of the material, comprehensively demonstrating a synergistic optimization trend in flame retardancy, mechanical properties, and aging resistance.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant polypropylene plastic, characterized in that, It is composed of the following raw materials in parts by weight: 70-80 parts polypropylene, 15-25 parts halogen-free flame retardant, 1-5 parts flame retardant synergist, 5-15 parts toughening agent, 0.1-0.5 parts antioxidant, and 0.5-2 parts lubricant. The halogen-free flame retardant is a compound represented by Formula 1 below: Formula 1: ; In Formula 1, R1 is selected from any one of hydrogen, methoxy, ethyl, and propyl.

2. The polypropylene flame-retardant plastic according to claim 1, characterized in that, The polypropylene is homopolymer polypropylene with a melt index of 2-10 g / 10 min.

3. The polypropylene flame-retardant plastic according to claim 1, characterized in that, The halogen-free flame retardant is any one of the compounds shown in the following structures: ； 。 4. The flame-retardant polypropylene plastic according to claim 1, characterized in that, The flame retardant synergist is at least one of nano-montmorillonite or zinc oxide.

5. The polypropylene flame-retardant plastic according to claim 1, characterized in that, The toughening agent is an ethylene-octene copolymer.

6. The polypropylene flame-retardant plastic according to claim 1, characterized in that, The antioxidant is a compound of antioxidant 1010 and antioxidant 168, with a mass ratio of 1:

1.

7. The polypropylene flame-retardant plastic according to claim 1, characterized in that, The lubricant is a compound of butyl stearate and ethylene bis-stearamide, with a mass ratio of 1:

1.

8. A method for preparing a flame-retardant polypropylene plastic according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Place the polypropylene, halogen-free flame retardant, flame retardant synergist, toughening agent, antioxidant and lubricant in a drying oven at 60-80℃ and dry for 2-4 hours to remove moisture from the raw materials; S2. Add the pretreated polypropylene and toughening agent to a high-speed mixer and mix for 5-8 minutes at a speed of 800-1200 r / min. Then add the pretreated halogen-free flame retardant, flame retardant synergist, antioxidant and lubricant, and continue mixing for 8-15 minutes until the materials are evenly mixed to obtain the premix. S3. The premixed material is added to a twin-screw extruder, and the temperature of each section of the extruder is controlled as follows: feeding section 150-160℃, compression section 170-180℃, homogenization section 180-190℃, die head temperature 185-195℃, and screw speed 150-250r / min. After melting, shearing and mixing, the material is extruded from the die head to obtain an extruded melt. S4. After the extruded melt is cooled to room temperature by water cooling, it is pelletized by a pelletizer and dried in a hot air circulating oven at 70-80℃ for 3-5 hours to remove surface moisture, thus obtaining a flame-retardant polypropylene plastic.

9. The method for preparing a flame-retardant polypropylene plastic according to claim 8, characterized in that, During the mixing process of the high-speed mixer in S2, cooling water is introduced through the jacket to control the temperature of the mixed materials to not exceed 50°C, so as to avoid the raw materials from melting and sticking due to excessive temperature.

10. The application of a polypropylene flame-retardant plastic as described in any one of claims 1-7 in a plastic running track.

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