Flame retardant plastic material and preparation method thereof

Abstract

The invention relates to the technical field of flame retardant plastics, and in particular to a flame retardant plastic material and a preparation method thereof. The invention adopts a reactive phosphorus-nitrogen flame retardant to improve the flame retardant performance of polypropylene plastics. The flame retardant of the invention uses phosphorus and nitrogen as main flame retardant elements, which work synergistically, have high flame retardant efficiency and good thermal stability. The prepared phosphorus-nitrogen flame retardant has double bond groups, which can undergo polymerization reaction with a small amount of double bonds remaining in polypropylene plastics under melting conditions, thereby being grafted onto polypropylene molecular chains, thereby improving the compatibility of the flame retardant in a matrix and obtaining a longer-lasting and effective flame retardant effect.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant plastics, and in particular to a flame retardant plastic material and a preparation method thereof. Background Art

[0002] Polypropylene is a polymer of propylene and one of the four general-purpose plastics. It has the characteristics of light weight, non-toxicity, heat resistance, corrosion resistance, good mechanical properties, low water absorption, and excellent mechanical properties. It is widely used in many fields such as automotive parts, electronic appliances, medical care, clothing, etc. However, due to the low oxygen index of polypropylene itself, it is very easy to burn, and the heat generated during combustion is high, a large amount of corrosive and toxic gases and smoke are generated, and the molten droplets cause the flame to spread during combustion, causing heavy casualties and property losses. This greatly limits the application field of polypropylene. Therefore, there is an urgent technical demand and a broad market demand for the flame retardant modification of polypropylene.

[0003] The modification of polypropylene is usually to add flame retardants, which include halogen flame retardants, filled flame retardants and intumescent flame retardants. Halogen flame retardants are a type of flame retardants that contain halogen elements and use halogen elements to play a flame retardant role. The flame retardant mechanism includes blocking cooling, terminating chain reactions, and cutting off heat sources. However, since halogen flame retardants are prone to produce harmful substances such as dioxins during the flame retardant process, they are not environmentally friendly, and their use has been restricted at present. Filled flame retardants include magnesium hydroxide, aluminum hydroxide, etc., which release bound water during combustion and heat decomposition, absorb a large amount of latent heat, and reduce the temperature of the filled material in the flame, thereby playing a flame retardant effect. The oxides produced by decomposition are also good refractory materials, which can help improve the temperature resistance of polymer materials. At the same time, the released water vapor is also a smoke suppressant. However, filled flame retardants such as magnesium hydroxide and aluminum hydroxide have a large density. Adding them to polypropylene will increase the density of polypropylene materials, limiting its application areas. At the same time, current flame retardants are usually physically mixed in the plastic matrix, and are prone to migration and precipitation problems during long-term application, resulting in reduced flame retardant efficiency and a short flame retardant effect. Intumescent flame retardants, also known as nitrogen-phosphorus flame retardants, use phosphorus and nitrogen as the main flame retardant components. They are a new type of halogen-free and environmentally friendly flame retardant that integrates carbon source, acid source and gas source. When heated, this type of flame retardant can produce a phosphorus-nitrogen synergistic flame retardant effect in the molecule, and a layer of carbon foam will be generated on the surface of the plastic when burning, thereby playing a role in heat insulation, oxygen isolation, smoke suppression, and drip prevention. However, some intumescent flame retardants still have the problem of poor thermal stability. Therefore, the development of intumescent flame retardants has broad market prospects. Summary of the invention

[0004] The purpose of the present invention is to provide a flame-retardant polypropylene plastic with high flame retardant efficiency, good thermal stability, good compatibility and long-lasting flame retardant effect, so as to overcome the problems existing in the prior art that halogen flame retardants are not environmentally friendly, filled flame retardants easily lead to increased density of polypropylene materials, limited application fields, low flame retardant efficiency, poor thermal stability and short flame retardant effect.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A flame retardant plastic material, which is composed of the following raw materials by weight: 100 parts of polypropylene resin, 20-35 parts of reactive phosphorus-nitrogen flame retardant, 10-15 parts of toughening agent, 5-6 parts of compatibilizer, 1-3 parts of antioxidant, and 0.2-0.5 parts of initiator;

[0007] Furthermore, as a preferred technical solution of the present invention, the toughening agent is selected from: styrene-butadiene-styrene block copolymer (SBS), ethylene propylene diene monomer rubber (EPDM), natural rubber (NR) or a combination of two or more thereof.

[0008] Furthermore, as a preferred technical solution of the present invention, the compatibilizer is selected from: ethylene-vinyl acetate copolymer (EVA), maleic anhydride grafted polypropylene, or a combination of two thereof.

[0009] Furthermore, as a preferred technical solution of the present invention, the antioxidant is selected from: antioxidant 1010, antioxidant 1076 or antioxidant 168, or a combination of two or more thereof.

[0010] Furthermore, as a preferred technical solution of the present invention, the initiator is selected from: dibenzoyl peroxide, methyl ethyl ketone peroxide, or a combination of two thereof.

[0011] Furthermore, the present invention also provides a preparation process of a flame retardant plastic material, and the specific operation steps are as follows:

[0012] According to the proportion, 100 parts of polypropylene resin, 20-35 parts of reactive phosphorus-nitrogen flame retardant, 10-15 parts of toughening agent, 5-6 parts of compatibilizer, 1-3 parts of antioxidant and 0.2-0.5 parts of initiator are put into a high-speed mixer for mixing to make the materials dispersed evenly. When the temperature of the mixed material rises to 90-120°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0013] Furthermore, as a preferred technical solution of the present invention, the preparation steps of the reactive phosphorus-nitrogen flame retardant are as follows:

[0014] (1) Synthesis of DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-di(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide):

[0015] The specific synthetic route is: ;

[0016] The specific operation steps are as follows: (1) adding 162 g of 37% formaldehyde aqueous solution and 210.8 g of diethanolamine to a reaction bottle with a mechanical stirring device, stirring the reaction, controlling the reaction temperature not to exceed 40°C, and the reaction time to be 2-3 h, and removing water under vacuum to obtain a viscous intermediate 3-(2-hydroxyethyl)-1,3-oxazacyclopentane, then adding 200-300 ml of dioxane, 432.8 g of DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and 3 g of a strongly acidic ion exchange resin catalyst to the above intermediate, stirring the mixture to react for 3-4 h, and rotary evaporating the above mixture to recover dioxane to obtain a yellow viscous substance, and washing, drying and crushing the obtained yellow viscous substance to obtain a white powder DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-di(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide);

[0017] (2) Synthesis of reactive phosphorus-nitrogen flame retardants:

[0018] The specific reaction steps are as follows: add dimethylformamide, 2,4-diamino-6-methyl-1,3,5-triazine, DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-di(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide), toluene diisocyanate, and catalyst 1 into a reaction bottle with a mechanical stirring device, stir the reaction, control the reaction temperature at 40-60°C, and react for 1-2 hours. After the reaction is completed, a polyurethane prepolymer is obtained. Add hydroxyethyl acrylate and catalyst 2 to the above polyurethane prepolymer, continue the reaction for 2-3 hours, and obtain a reactive phosphorus-nitrogen flame retardant.

[0019] Furthermore, as a preferred technical solution of the present invention, the strong acid ion exchange resin catalyst in step (1) is D001 strong acid resin catalyst or D002 strong acid resin catalyst;

[0020] Furthermore, as a preferred technical solution of the present invention, in the step (2), the molar ratio of toluene diisocyanate to 2,4-diamino-6-methyl-1,3,5-triazine, DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-bis(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide), and hydroxyethyl acrylate is 2.5:1:1:1.5;

[0021] By controlling the dosage ratio, 2,4-diamino-6-methyl-1,3,5-triazine, DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-bis(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide) and toluene diisocyanate are reacted to obtain a terminal isocyanate intermediate product, which is further reacted with hydroxyethyl acrylate to finally obtain an acrylate-terminated product.

[0022] Furthermore, as a preferred technical solution of the present invention, the catalyst 1 in the step (2) is selected from one or a combination of two or more of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate; the catalyst 2 in the step (2) is selected from one or a combination of two or more of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate.

[0023] The amount of catalyst 1 used in step (2) is 1-3 g;

[0024] The amount of catalyst 2 used in step (2) is 1-3 g.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The flame-retardant plastic material prepared by the present invention uses DOPO-DAM (9,10-dihydro-9-oxa-10-[N,N-bis(hydroxyethyl)aminomethyl]-10-phosphaphenanthrene-10-oxide) as a phosphorus source, 2,4-diamino-6-methyl-1,3,5-triazine and toluene diisocyanate as nitrogen sources, and uses toluene diisocyanate to bond the above phosphorus source and nitrogen source to form an intumescent flame retardant containing nitrogen, phosphorus and carbon elements. The flame-retardant plastic material prepared by the present invention has the characteristics of good high-temperature stability, high carbonization rate, and halogen-free and environmentally friendly through the synergistic combination of phosphorus, nitrogen and carbon elements.

[0027] (2) The present invention uses acrylic ester to end-cap the synthesized intumescent flame retardant, introducing carbon-carbon double bonds into its molecular structure. The carbon-carbon double bonds undergo polymerization reaction with a small amount of double bonds remaining in the polypropylene plastic under the action of free radicals, thereby being grafted onto the polypropylene molecular chain, which not only improves the compatibility of the flame retardant in the matrix, but also further improves its mechanical properties and flame retardancy. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0029] Experimental Example 1

[0030] The reactive phosphorus-nitrogen flame retardant is prepared by the following steps:

[0031] (1) Synthesis of DOPO-DAM:

[0032] Add 162 g of 37% formaldehyde aqueous solution and 210.8 g of diethanolamine to a reaction bottle with a mechanical stirring device, stir and react, control the reaction temperature to 40°C, react for 3 h, remove water under vacuum, and obtain a viscous intermediate 3-(2-hydroxyethyl)-1,3-oxazacyclopentane, then add 300 ml of dioxane, 432.8 g of DOPO and 3 g of D001 strong acid resin catalyst to the intermediate, stir and react the mixture for 3 h, and rotary evaporate the mixture to recover dioxane to obtain a yellow viscous substance, wash, dry and crush the obtained yellow viscous substance to obtain a white powder DOPO-DAM;

[0033] (2) Synthesis of reactive phosphorus-nitrogen flame retardants:

[0034] In a reaction bottle equipped with a mechanical stirring device, 300 ml of dimethylformamide, 1 mol of 2,4-diamino-6-methyl-1,3,5-triazine, 1 mol of DOPO-DAM, 2.5 mol of toluene diisocyanate, and 2 g of dibutyltin dilaurate as a catalyst were added, and the reaction was stirred. The reaction temperature was controlled at 55°C and the reaction time was 2 h. After the reaction was completed, a polyurethane prepolymer was obtained. 1.5 mol of hydroxyethyl acrylate and 1.0 g of dibutyltin dilaurate as a catalyst were added to the above polyurethane prepolymer, and the reaction was continued at 55°C for 2.5 h to allow the hydroxyl group of hydroxyethyl acrylate to react with the isocyanate group as completely as possible to obtain a reactive phosphorus-nitrogen flame retardant.

[0035] Experimental Example 2

[0036] (1) Synthesis of reactive phosphorus-nitrogen flame retardants:

[0037] 300 ml of dimethylformamide, 2 mol of 2,4-diamino-6-methyl-1,3,5-triazine, 2.5 mol of toluene diisocyanate, and 2 g of dibutyltin dilaurate catalyst were added to a reaction bottle with a mechanical stirring device, and the reaction was stirred. The reaction temperature was controlled at 55°C and the reaction time was 2 hours. After the reaction was completed, a polyurethane prepolymer was obtained. 1.5 mol of hydroxyethyl acrylate and 1 g of dibutyltin dilaurate catalyst were added to the above polyurethane prepolymer, and the reaction was continued at 55°C for 2.5 hours to make the hydroxyl group of hydroxyethyl acrylate react with the isocyanate group as completely as possible to obtain a reactive phosphorus-nitrogen flame retardant.

[0038] Experimental Example 3

[0039] The reactive phosphorus-nitrogen flame retardant is prepared by the following steps:

[0040] (1) Synthesis of DOPO-DAM:

[0041] Add 162 g of 37% formaldehyde aqueous solution and 210.8 g of diethanolamine to a reaction bottle with a mechanical stirring device, stir and react, control the reaction temperature to 40°C, react for 3 h, remove water under vacuum, and obtain a viscous intermediate 3-(2-hydroxyethyl)-1,3-oxazacyclopentane, then add 300 ml of dioxane, 432.8 g of DOPO and 3 g of D001 strong acid resin catalyst to the intermediate, stir and react the mixture for 3 h, and rotary evaporate the mixture to recover dioxane to obtain a yellow viscous substance, wash, dry and crush the obtained yellow viscous substance to obtain a white powder DOPO-DAM;

[0042] (2) Synthesis of reactive phosphorus-nitrogen flame retardants:

[0043] 300 ml of dimethylformamide, 2 mol of DOPO-DAM, 2.5 mol of toluene diisocyanate, and 2 g of dibutyltin dilaurate catalyst were added to a reaction bottle with a mechanical stirring device, and the reaction was stirred. The reaction temperature was controlled at 55°C and the reaction time was 2 hours. After the reaction was completed, a polyurethane prepolymer was obtained. 1.5 mol of hydroxyethyl acrylate and 1 g of dibutyltin dilaurate catalyst were added to the above polyurethane prepolymer, and the reaction was continued at 55°C for 2.5 hours to react the hydroxyl group of hydroxyethyl acrylate with the isocyanate group to obtain a reactive phosphorus-nitrogen flame retardant.

[0044] Experimental Example 4

[0045] The reactive phosphorus-nitrogen flame retardant is prepared by the following steps:

[0046] (1) Synthesis of DOPO-DAM:

[0047] 162 g of 37% formaldehyde aqueous solution and 210.8 g of diethanolamine were added to a reaction bottle equipped with a mechanical stirring device, and the reaction was stirred. The reaction temperature was controlled to be 40°C, the reaction time was 3 h, and water was removed in vacuo to obtain a viscous intermediate 3-(2-hydroxyethyl)-1,3-oxazacyclopentane. Subsequently, 300 ml of dioxane, 432.8 g of DOPO and 3 g of D001 strong acid resin catalyst were added to the above intermediate, and the mixture was stirred for reaction for 3 h. The above mixture was rotary evaporated to recover dioxane to obtain a yellow viscous substance. The obtained yellow viscous substance was washed, dried, and crushed to obtain a white powder DOPO-DAM.

[0048] (2) Synthesis of phosphorus-nitrogen flame retardants:

[0049] The specific reaction steps are as follows: add 300 ml of dimethylformamide, 1 mol of 2,4-diamino-6-methyl-1,3,5-triazine, 1 mol of DOPO-DAM, 2.5 mol of toluene diisocyanate, and 2 g of catalyst dibutyltin dilaurate into a reaction bottle with a mechanical stirring device, stir the reaction, control the reaction temperature at 55°C, and react for 2 hours. After the reaction is completed, a phosphorus-nitrogen flame retardant is obtained.

[0050] Example 1

[0051] Preparation of flame retardant plastic materials:

[0052] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 20 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 1, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0053] The specific preparation process of flame retardant plastic materials is as follows:

[0054] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0055] Example 2

[0056] Preparation of flame retardant plastic materials:

[0057] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 25 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 1, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0058] The specific preparation process of flame retardant plastic materials is as follows:

[0059] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0060] Example 3

[0061] Preparation of flame retardant plastic materials:

[0062] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 35 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 1, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0063] The specific preparation process of flame retardant plastic materials is as follows:

[0064] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0065] Example 4

[0066] Preparation of flame retardant plastic materials:

[0067] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 33 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 1, 15 parts of EPDM rubber, 6 parts of maleic anhydride grafted polypropylene, 3 parts of antioxidant 1076, and 0.5 parts of methyl ethyl ketone peroxide;

[0068] The specific preparation process of flame retardant plastic materials is as follows:

[0069] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0070] Comparative Example 1

[0071] Preparation of flame retardant plastic materials:

[0072] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 20 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 2, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0073] The specific preparation process of flame retardant plastic materials is as follows:

[0074] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0075] Comparative Example 2

[0076] Preparation of flame retardant plastic materials:

[0077] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 20 parts of reactive phosphorus-nitrogen flame retardant prepared in Experimental Example 3, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0078] The specific preparation process of flame retardant plastic materials is as follows:

[0079] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0080] Comparative Example 3

[0081] Preparation of flame retardant plastic materials:

[0082] The composition of each component raw material is calculated by weight: 100 parts of polypropylene resin, 20 parts of phosphorus nitrogen flame retardant prepared in Experimental Example 4, 12 parts of styrene-butadiene-styrene block copolymer, 5 parts of ethylene-vinyl acetate copolymer, 2 parts of antioxidant 1010, and 0.2 parts of dibenzoyl peroxide;

[0083] The specific preparation process of flame retardant plastic materials is as follows:

[0084] The raw materials are put into a high-speed mixer according to the above ratio to mix, so that the materials are evenly dispersed. When the temperature of the mixed material rises to 100°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

[0085] Application examples:

[0086] The polypropylene flame-retardant plastic materials obtained in Examples 1-4 and Comparative Examples 1-3 were respectively processed into injection-molded specimens in a vertical injection molding machine, and the following performance tests were performed:

[0087] Mechanical properties: The tensile strength is tested in accordance with GB / T1040.2-2006, the sample size is 150mm*20mm*4mm, and the running speed is 50mm / min; the cantilever beam notch impact strength is tested in accordance with GB / T1843-2008;

[0088] The limiting oxygen index is tested according to GB / T2406.2-2009, and the sample size is 80mm×10mm×4mm; the vertical burning test (UL-94) is tested according to GB / T2048-2008; the sample size is 120mm×12.5mm×3.0mm.

[0089] The measured results are shown in Table 1:

[0090] Table 1

[0091]

[0092] According to the results in Table 1, the flame retardant plastic material of polypropylene prepared in Example 1 is superior to that of Comparative Examples 1-3 in terms of flame retardancy and mechanical properties;

[0093] The polypropylene flame retardant plastic material prepared by the present invention not only has the characteristics of good high temperature stability, high carbonization rate, halogen-free and environmentally friendly through the coordinated coordination of phosphorus, nitrogen and carbon elements, but also improves the compatibility of the flame retardant in the matrix, and further improves its mechanical properties and flame retardancy.

[0094] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the defined scope, they should all fall within the protection scope of the present invention.

Claims

1. A flame retardant plastic material, characterized in that: The invention is composed of the following raw materials according to weight: 100 parts of polypropylene resin, 20-35 parts of reactive phosphorus-nitrogen flame retardant, 10-15 parts of toughening agent, 5-6 parts of compatibilizer, 1-3 parts of antioxidant and 0.2-0.5 parts of initiator; The reactive phosphorus-nitrogen flame retardant is prepared by the following steps: (1) Synthesis of DOPO-DAM: Add 37% formaldehyde aqueous solution and diethanolamine to a reaction bottle with a mechanical stirring device, stir and react, control the reaction temperature not to exceed 40°C, react for 2-3 hours, remove water under vacuum, and obtain a viscous intermediate 3-(2-hydroxyethyl)-1,3-oxazacyclopentane. Then add dioxane, DOPO and a strong acid ion exchange resin catalyst to the intermediate, stir and react the mixture for 3-4 hours, and after the reaction is completed, recover dioxane by rotary evaporation. The residue is a yellow viscous substance. Wash, dry and crush the obtained residue to obtain a white powder DOPO-DAM. (2) Synthesis of reactive phosphorus-nitrogen flame retardants: Add dimethylformamide, 2,4-diamino-6-methyl-1,3,5-triazine, DOPO-DAM, toluene diisocyanate, and catalyst 1 into a reaction bottle with a mechanical stirring device, stir and react, control the reaction temperature at 40-60° C., and react for 1-2 hours. After the reaction is completed, a polyurethane prepolymer is obtained. Add hydroxyethyl acrylate and catalyst 2 to the polyurethane prepolymer, and continue to react for 2-3 hours to obtain a reactive phosphorus-nitrogen flame retardant; In the step (2), the molar ratio of toluene diisocyanate to 2,4-diamino-6-methyl-1,3,5-triazine, DOPO-DAM, and hydroxyethyl acrylate is 2.5:1:1:1.5; The catalyst 1 in step (2) is selected from one or a combination of two or more of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate; the catalyst 2 in step (2) is selected from one or a combination of two or more of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate.

2. The flame retardant plastic material according to claim 1, characterized in that: The toughening agent is selected from one or a combination of two or more of styrene-butadiene-styrene block copolymer, ethylene propylene diene monomer rubber, and natural rubber.

3. The flame retardant plastic material according to claim 1, characterized in that: The compatibilizer is selected from ethylene-vinyl acetate copolymer, maleic anhydride grafted polypropylene, or a combination of two thereof.

4. The flame retardant plastic material according to claim 1, characterized in that: The antioxidant is selected from one of antioxidant 1010, antioxidant 1076 or antioxidant 168, or a combination of two or more thereof.

5. The flame retardant plastic material according to claim 1, characterized in that: The initiator is selected from dibenzoyl peroxide, methyl ethyl ketone peroxide, or a combination of the two.

6. The method for preparing a flame retardant plastic material according to claim 1, characterized in that: The preparation process of the flame retardant plastic material is as follows: According to the proportion, 100 parts of polypropylene resin, 20-35 parts of reactive phosphorus-nitrogen flame retardant, 10-15 parts of toughening agent, 5-6 parts of compatibilizer, 1-3 parts of antioxidant and 0.2-0.5 parts of initiator are put into a high-speed mixer for mixing to make the materials dispersed evenly. When the temperature of the mixed material rises to 90-120°C, the discharged material is cooled, and the cooled mixed material is sent to a twin-screw extruder for melt extrusion to obtain a strip material. The extruded strip material is cooled in a water tank, pulled into a pelletizer for granulation, and dried to obtain a polypropylene flame-retardant plastic material.

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