A flame-retardant master batch for polypropylene and a preparation method thereof

Abstract

The application belongs to the technical field of flame-retardant masterbatch, and particularly relates to a kind of flame-retardant masterbatch for polypropylene and a preparation method thereof, wherein tri (2-hydroxyethyl) isocyanurate is heated and melted, tetrabutyl titanate and DOPO-DPP are added into the tri (2-hydroxyethyl) isocyanurate, melamine and cyanuric acid are added into the mixture after 3-4 hours of reaction, and the mixture is cooled and crushed after 30 minutes of reaction to obtain a macromolecular flame retardant TDMC; a free radical trapping agent is prepared by ester exchange reaction of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1,3,5-triazine and 2,2,6,6-tetramethylpiperidinol; polypropylene, TDMC, the free radical trapping agent and zeolite are loaded into a high-speed mixer and stirred and mixed, and then extruded and granulated. The macromolecular flame retardant TDMC has a large molecular weight and good water resistance, and improves the compatibility and hygrothermal stability of the flame-retardant masterbatch in polypropylene.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame-retardant masterbatch, and particularly relates to a flame-retardant masterbatch for polypropylene and a preparation method thereof. BACKGROUND

[0002] Polypropylene (PP) is a non-polar semi-crystalline thermoplastic polymer formed by addition polymerization of propylene monomers. Due to its excellent mechanical properties, chemical corrosion resistance and processability, it is widely used in electronic and electrical, construction, packaging and medical fields. However, due to the lack of flame-retardant elements in its carbon-hydrogen main chain structure, polypropylene itself is highly flammable and produces high-temperature molten droplets during combustion, which severely limits its application in high-safety scenarios.

[0003] In the modification of polypropylene, commonly used flame retardants include halogen-based flame retardants, inorganic filler flame retardants, silicon-based flame retardants, phosphorus-based flame retardants and intumescent flame retardants. Among them, halogen-based flame retardants have excellent gas-phase flame-retardant effect, but they release toxic and corrosive gases during combustion and have been gradually restricted. In contrast, intumescent flame retardants, due to their halogen-free, efficient carbonization and combined gas-phase and condensed-phase flame-retardant mechanisms, have become the focus of polypropylene flame-retardant research.

[0004] Currently, intumescent flame retardant (IFR) is one of the commonly used flame-retardant systems in polypropylene, which is usually a mixture of carbon source, acid source and gas source in a certain proportion. However, due to the high polarity of IFR and the non-polarity of PP, the large difference in polarity between the two may cause the following problems: poor compatibility, uneven dispersion, easy migration and precipitation when exposed to water, etc. SUMMARY

[0005] The purpose of the present application is to provide a flame-retardant masterbatch for polypropylene and a preparation method thereof to solve the above technical problems.

[0006] To achieve the above technical purpose, the technical scheme of the present application is as follows:

[0007] A preparation method of a flame-retardant masterbatch for polypropylene, comprising the following steps:

[0008] S1, after heating and melting tris (2-hydroxyethyl) isocyanurate, catalyst tetrabutyl titanate and DOPO-DPP are added thereto, and the mixture is stirred at 160-165℃ for 3-4h. After the reaction is completed, melamine and cyanuric acid are added thereto, and the mixture is stirred at 190-195℃ for 30min to obtain a viscous melt. After cooling and crushing, a macromolecular flame retardant TDMC is obtained;

[0009] S2, a radical scavenger is prepared by an ester exchange reaction of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1, 3, 5-triazine and 2, 2, 6, 6-tetramethylpiperidinol;

[0010] S3, 40-50 parts of polypropylene, 50-60 parts of TDMC, 10-15 parts of the radical scavenger and 3-5 parts of zeolite are loaded into a high-speed mixer and stirred and mixed, and then extruded and granulated to obtain a flame-retardant master batch for polypropylene, and the extrusion temperature is 150-160℃.

[0011] As a further improvement, in step S1, the preparation method of the DOPO-DPP is as follows: diamino diphenyl sulfone, p-formyl benzoic acid and tetrahydrofuran solvent are mixed, stirred and reacted at 50-80℃ for 5-6h under a nitrogen atmosphere, the reaction liquid is cooled to room temperature after the reaction is completed, DOPO is added, and stirred and reacted for 12-15h under a nitrogen atmosphere, and the filter cake obtained after filtration is washed with tetrahydrofuran for 3 times and dried to obtain DOPO-DPP.

[0012] As a further improvement, the molar ratio of the diamino diphenyl sulfone, p-formyl benzoic acid and DOPO is 0.8-1:2:2.

[0013] As a further improvement, in step S2, the preparation method of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1, 3, 5-triazine is as follows:

[0014] S21, trichloro cyanuric acid, chlorobenzene and aluminum chloride are mixed and stirred to cool to 0-5℃, benzene is slowly added, stirred and reacted for 2h, then naturally warmed to room temperature and stirred and reacted for 12h, then warmed to 50℃ and slowly added with m-dihydroxybenzene, then warmed to 75-80℃ and reacted for 5h, after the reaction is completed, chlorobenzene is removed by azeotropic distillation, then cooled to 60℃ and filtered, and the precipitate is dried and recrystallized to obtain 2,4-diphenyl-6- (2, 4-dihydroxyphenyl) -1, 3, 5-triazine;

[0015] S22, 2, 4-diphenyl-6- (2, 4-dihydroxyphenyl) -1, 3, 5-triazine, butyl acetate and potassium carbonate are mixed and stirred to warm to 60℃, and ethyl chloroacetate is added dropwise, the dropping is completed in 2h, and reacted at 60-65℃ for 6h, then warmed to 100℃ and filtered, the filtrate is collected and cooled to crystallize, and the solid is dried and recrystallized to obtain 2, 4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1, 3, 5-triazine.

[0016] As a further improvement, the molar ratio of cyanuric chloride, benzene and resorcinol is 1:1.95~2:1.1, and the molar ratio of 4-diphenyl-6-(2,4-dihydroxyphenyl)-1,3,5-triazine and ethyl chloroacetate is 1:1.1~1.2.

[0017] As a further improvement, in step S1, the molar ratio of tris(2-hydroxyethyl) isocyanurate, DOPO-DPP, melamine and cyanuric acid is 1:3:3:3.

[0018] As a further improvement, in step S2, the preparation method of the radical scavenger is specifically as follows: 2,4-diphenyl-6-[(2-hydroxy-4-ethoxycarbonylmethoxy)phenyl]-1,3,5-triazine, 2,2,6,6-tetramethylpiperidinol and a catalyst dibutyl tin oxide are mixed, then a solvent o-dichlorobenzene is added thereto, and the mixture is reacted at 150~155℃ for 8h under nitrogen protection, after the reaction is completed, activated carbon is added for decolorization, and the filtrate is crystallized after hot filtration, and the solid is collected and recrystallized to obtain the radical scavenger.

[0019] As a further improvement, the molar ratio of 2,4-diphenyl-6-[(2-hydroxy-4-ethoxycarbonylmethoxy)phenyl]-1,3,5-triazine and 2,2,6,6-tetramethylpiperidinol is 1:1~1.1.

[0020] The application also provides a flame-retardant master batch for polypropylene.

[0021] Due to the adoption of the above technical solutions, the application has the following beneficial effects:

[0022] The flame-retardant master batch for polypropylene and the preparation method thereof provided by the application adopt a macromolecular flame retardant TDMC, which has a large molecular weight and good water resistance, and improves the compatibility and hygrothermal stability of the flame-retardant master batch in polypropylene; in the heating process, melamine and cyanuric acid in TDMC are separated and release ammonia gas and other gases, then the ester bond between THEIC and DOPO-DPP is broken to form carboxylic acid and olefin substances, DOPO-DPP continues to play the roles of gas phase and condensed phase flame retardant in the heating process, and the olefin substances generated in the heating process can generate various carbon precursor and corresponding condensed ring structures to form a black viscous carbon skeleton, thus having better flame-retardant effect.

[0023] In the present application, the macromolecular flame retardant TDMC has higher thermal stability, the sulfur atom in the DOPO-DPP structure is in the highest oxidation state, has strong electron-withdrawing ability, and the benzene ring connected with the sulfone group is in an oxidation-resistant state due to lack of electrons, thereby improving the overall thermal stability of the macromolecular flame retardant TDMC; meanwhile, the multiple benzene ring structures in the TDMC have higher mechanical strength after forming a carbon layer, thereby improving the strength of the carbon layer, preventing the carbon layer from becoming loose due to excessive expansion, and making the formed carbon layer more expanded and not weakened in strength.

[0024] The macromolecular flame retardant TDMC can also improve the viscosity of the material after being heated and melted, inhibit the migration of the melt droplets to the surface of the base material, provide more time for the formation of the carbon layer, and prevent the melt droplets from dropping before the carbon layer is formed.

[0025] The free radical trapping agent prepared in the present application can generate the free radical trapping agent while playing a gas source role, trap the free radicals generated in the thermal decomposition process of the polypropylene, and further improve the flame retardant performance of the flame retardant master batch. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is an infrared spectrum of the macromolecular flame retardant TDMC and the THEIC, DOPO prepared in Example 1;

[0027] Figure 2 is an infrared spectrum of the free radical trapping agent prepared in Example 1. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely in combination with the specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, rather than all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0029] Example 1 A flame retardant master batch for polypropylene, by weight fraction, comprises the following components: 40 parts of polypropylene, 50 parts of TDMC, 10 parts of a free radical trapping agent, and 3 parts of zeolite.

[0030] The preparation method of the above flame retardant master batch for polypropylene comprises the following steps:

[0031] S1, preparation of DOPO-DPP;

[0032] The 0.8 mol of diaminodiphenyl sulfone, 2 mol of p-formyl benzoic acid and 250 mL of tetrahydrofuran solvent are mixed, and the reaction is stirred at 50°C for 6 h under nitrogen atmosphere. After the reaction is completed, the reaction solution is cooled to room temperature, 2 mol of DOPO is added, and the reaction is stirred for 12 h under nitrogen atmosphere. After the reaction is completed, the filter cake is obtained by filtration, and the filter cake is washed with 5°C tetrahydrofuran for 3 times, and dried to obtain DOPO-DPP;

[0033] The reaction equation is as follows:

[0034] ;

[0035] ;

[0036] S2, Preparation of the macromolecular flame retardant TDMC;

[0037] The 0.4 mol of tri (2-hydroxyethyl) isocyanurate (THEIC) is heated and melted, 2.0 g of catalyst tetrabutyl titanate and 1.2 mol of DOPO-DPP are added, and the reaction is stirred at 160°C for 4 h. After the reaction is completed, 1.2 mol of melamine and 1.2 mol of cyanuric acid are added, and the reaction is stirred at 190°C for 30 min to obtain a viscous melt. After cooling and crushing, the macromolecular flame retardant TDMC is obtained;

[0038] The infrared spectra of the obtained macromolecular flame retardant TDMC and THEIC, DOPO are shown in Figure 1 The O-H characteristic peak in THEIC disappears in TDMC, and in TDMC, the characteristic peak of C=O appears at 1735 cm -1 , the characteristic peak of C-O-C appears at 1150 cm -1 , which indicates the formation of ester bond, and the characteristic peaks of -NH2 and -NH3 -1 appear at 3407 cm -1 and 1544 cm + respectively in TDMC, the P=O characteristic peak exists at 1300 cm -1 , and the P-O-Ph characteristic peak appears at 907 cm -1 , the P-H bond characteristic absorption peak of DOPO at 2435 cm -1 does not appear in the infrared spectrum of TDMC, and the characteristic peak of Schiff base does not appear at 1600 cm -1 ~1680 cm -1 in the infrared spectrum of TDMC;

[0039] S3, Preparation of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1,3,5-triazine;

[0040] 0.1 mol cyanuric chloride, 100 mL chlorobenzene, and 40 g aluminum trichloride were mixed and stirred, then cooled to 5 °C. 0.195 mol benzene was slowly added to the mixture, and the mixture was stirred for 2 h. The mixture was then naturally heated to room temperature and stirred for 12 h. The mixture was then heated to 50 °C and 0.11 mol resorcinol was slowly added. The mixture was then heated to 75 °C and reacted for 5 h. After the reaction was completed, chlorobenzene was removed by azeotropic distillation. The mixture was then cooled to 60 °C and filtered. The precipitate was dried and recrystallized in N,N-dimethylformamide to obtain 2,4-diphenyl-6-(2,4-dihydroxyphenyl)-1,3,5-triazine.

[0041] The reaction equation is:

[0042] ;

[0043] 0.05 mol of 2,4-diphenyl-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 90 mL of butyl acetate, and 8.0 g of potassium carbonate were mixed and stirred until the temperature reached 60 °C. 0.055 mol of ethyl chloroacetate was added dropwise over 2 hours. The mixture was reacted at 60 °C for 6 hours, then the temperature was raised to 100 °C and filtered. The filtrate was collected, cooled to 10 °C, and crystallized. The solid was collected, dried, and recrystallized in N,N-dimethylformamide to give 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethoxy)phenyl]-1,3,5-triazine.

[0044] The reaction equation is:

[0045] ;

[0046] S4. A free radical scavenger was prepared by transesterification of 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethoxy)phenyl]-1,3,5-triazine and 2,2,6,6-tetramethylpiperidinol.

[0047] Specifically, 0.02 mol of 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethoxy)phenyl]-1,3,5-triazine, 0.02 mol of 2,2,6,6-tetramethylpiperidinol and 0.4 g of dibutyltin oxide catalyst were mixed, and then 30 mL of o-dichlorobenzene solvent was added. The mixture was reacted at 150 °C for 8 h under nitrogen protection. After the reaction was completed, activated carbon was added for decolorization. The filtrate was then filtered hot and crystallized. The solid was collected and recrystallized in N,N-dimethylformamide to obtain a free radical scavenger.

[0048] Infrared spectra of free radical scavengers are as follows Figure 2 As shown, in the free radical scavenger, at 3424 cm⁻¹ -1 There is an absorption peak for OH at 2855~2963 cm⁻¹. -1 An absorption peak for CH is present at 1759 cm⁻¹.-1 absorption peak of C=O at 1348~1632cm -1 characteristic absorption peak of triazine ring and benzene ring at 1179cm -1 absorption peak of C-N;

[0049] S5, the polypropylene, TDMC, radical scavenger and zeolite are put into a high-speed mixer for stirring and mixing, and then extruded and granulated, with an extrusion temperature of 150°C. The specific method for extruding and granulating is prior art.

[0050] Example 2 A kind of polypropylene flame-retardant master batch, by weight parts, including the following components: 50 parts of polypropylene, 60 parts of TDMC, 15 parts of radical scavenger and 5 parts of zeolite.

[0051] The preparation method of the above-mentioned polypropylene flame-retardant master batch comprises the following steps:

[0052] S1, preparation of DOPO-DPP;

[0053] 1 mol of diaminodiphenyl sulfone, 2 mol of p-formyl benzoic acid and 250 mL of tetrahydrofuran solvent are mixed, stirred at 80°C for 5h under nitrogen atmosphere, and then cooled to room temperature. 2 mol of DOPO is added, stirred for 15h under nitrogen atmosphere, and then filtered. The obtained filter cake is washed with 5°C tetrahydrofuran for 3 times, and dried to obtain DOPO-DPP;

[0054] S2, preparation of macromolecular flame retardant TDMC;

[0055] After 0.4 mol of tris (2-hydroxyethyl) isocyanurate is heated and melted, 2.0 g of catalyst tetrabutyl titanate and 1.2 mol of DOPO-DPP are added, and stirred at 165°C for 3h. After the reaction is completed, 1.2 mol of melamine and 1.2 mol of cyanuric acid are added, and stirred at 195°C for 30min to obtain a viscous melt. After cooling and crushing, macromolecular flame retardant TDMC is obtained;

[0056] S3, preparation of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1,3,5-triazine;

[0057] Mix 0.1 mol cyanuric chloride, 100 mL chlorobenzene and 40 g aluminum chloride, and stir to cool to 0°C, slowly add 0.2 mol benzene thereto, stir to react for 2 h, then naturally warm to room temperature, stir to react for 12 h, then warm to 50°C, slowly add 0.11 mol resorcinol thereto, then warm to 80°C, react for 5 h, after the reaction is completed, remove chlorobenzene by azeotropic distillation, then cool to 60°C, filter, dry the precipitate, then recrystallize in N,N-dimethylformamide to obtain 2,4-diphenyl-6-(2,4-dihydroxyphenyl)-1,3,5-triazine;

[0058] Mix 0.05 mol 2,4-diphenyl-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 90 mL butyl acetate and 8.0 g potassium carbonate, stir to warm to 60°C, drop 0.06 mol ethyl chloroacetate thereto, drop for 2 h, react at 65°C for 6 h, then warm to 100°C, filter, cool the filtrate to 10°C to crystallize, collect the solid, dry, then recrystallize in N,N-dimethylformamide to obtain 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethyloxy)phenyl]-1,3,5-triazine;

[0059] S4, prepare the radical scavenger by an ester exchange reaction of 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethyloxy)phenyl]-1,3,5-triazine and 2,2,6,6-tetramethylpiperidinol;

[0060] Specifically, mix 0.02 mol 2,4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonylmethyloxy)phenyl]-1,3,5-triazine, 0.022 mol 2,2,6,6-tetramethylpiperidinol and 0.4 g catalyst dibutyl tin oxide, then add 30 mL solvent o-dichlorobenzene thereto, react at 155°C for 8 h under nitrogen protection, after the reaction is completed, decolorize by adding activated carbon, hot filter, then crystallize the filtrate, collect the solid, recrystallize in N,N-dimethylformamide to obtain the radical scavenger;

[0061] S5, mix polypropylene, TDMC, the radical scavenger and zeolite in a high-speed mixer, then extrude and granulate, and the extrusion temperature is 160°C.

[0062] The preparation method of the flame-retardant master batch for polypropylene comprises the following steps:

[0063] The preparation method of the flame-retardant master batch for polypropylene comprises the following steps:

[0064] S1, preparation of DOPO-DPP;

[0065] Mix 0.9 mol of diaminodiphenyl sulfone, 2 mol of p-formyl benzoic acid and 250 mL of tetrahydrofuran solvent, stir the reaction at 65℃ for 5.5 h under nitrogen atmosphere, after the reaction is completed, cool the reaction liquid to room temperature, add 2 mol of DOPO to it, stir the reaction for 13 h under nitrogen atmosphere, after the reaction is completed, filter, the obtained filter cake is washed with 5℃ tetrahydrofuran for 3 times, dry to obtain DOPO-DPP;

[0066] S2, Preparation of macromolecular flame retardant TDMC;

[0067] After heating and melting 0.4 mol of tris (2-hydroxyethyl) isocyanurate, add 2.0 g of catalyst tetrabutyl titanate and 1.2 mol of DOPO-DPP to it, stir the reaction at 163℃ for 3.5 h, after the reaction is completed, add 1.2 mol of melamine and 1.2 mol of cyanuric acid to it, stir the reaction at 193℃ for 30 min, obtain a viscous melt, after cooling and crushing, obtain macromolecular flame retardant TDMC;

[0068] S3, Preparation of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1, 3, 5-triazine;

[0069] Mix 0.1 mol of cyanuric chloride, 100 mL of chlorobenzene and 40 g of aluminum chloride, stir and cool to 3℃, slowly add 0.198 mol of benzene to it, stir the reaction for 2 h, then naturally warm to room temperature and stir the reaction for 12 h, then warm to 50℃, slowly add 0.11 mol of resorcinol, then warm to 78℃ and react for 5 h, after the reaction is completed, remove chlorobenzene by co-boiling distillation, then cool to 60℃ and filter, dry the precipitate, then recrystallize in N,N-dimethylformamide to obtain 2,4-diphenyl-6- (2, 4-dihydroxyphenyl) -1, 3, 5-triazine;

[0070] Mix 0.05 mol of 2,4-diphenyl-6- (2, 4-dihydroxyphenyl) -1, 3, 5-triazine, 90 mL of butyl acetate and 8.0 g of potassium carbonate, stir and warm to 60℃, add 0.58 mol of ethyl chloroacetate dropwise to it, drop for 2 h, react at 63℃ for 6 h, then warm to 100℃ and filter, cool the collected filtrate to 10℃ to crystallize, dry the collected solid, then recrystallize in N,N-dimethylformamide to obtain 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1, 3, 5-triazine;

[0071] S4, Preparation of radical scavenger by ester exchange reaction using 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1, 3, 5-triazine and 2, 2, 6, 6-tetramethylpiperidinol;

[0072] Specifically, 0.02 mol of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1,3,5-triazine, 0.021 mol of 2,2,6,6-tetramethylpiperidinol and 0.4 g of a catalyst dibutyl tin oxide are mixed, then 30 mL of a solvent o-dichlorobenzene is added, and the mixture is reacted at 153°C for 8 h under nitrogen protection. After the reaction is completed, activated carbon is added for decolorization, and the hot filtrate is crystallized and collected. The solid is recrystallized in N, N-dimethylformamide to obtain the free radical trapping agent.

[0073] S5, polypropylene, TDMC, free radical trapping agent and zeolite are loaded into a high-speed mixer and stirred and mixed, and then extruded and granulated, with an extrusion temperature of 155°C.

[0074] Example 4 A flame-retardant master batch for polypropylene, by weight fraction, comprising the following components: 48 parts of polypropylene, 53 parts of TDMC, 11 parts of a free radical trapping agent and 4 parts of zeolite.

[0075] The preparation method of the above-mentioned flame-retardant master batch for polypropylene is the same as that of Example 1.

[0076] Example 5 A flame-retardant master batch for polypropylene, by weight fraction, comprising the following components: 43 parts of polypropylene, 58 parts of TDMC, 11 parts of a free radical trapping agent and 4 parts of zeolite.

[0077] The preparation method of the above-mentioned flame-retardant master batch for polypropylene is the same as that of Example 1.

[0078] Comparative Example 1 A flame-retardant master batch for polypropylene, by weight fraction, comprising the following components: 40 parts of polypropylene, 50 parts of TDMC and 3 parts of zeolite.

[0079] The preparation method of TDMC and the preparation method of the flame-retardant master batch for polypropylene in this comparative example are the same as those of Example 1, with the only difference being the components used.

[0080] Comparative Example 2 A flame-retardant master batch for polypropylene, by weight fraction, comprising the following components: 40 parts of polypropylene, 10 parts of a free radical trapping agent and 3 parts of zeolite.

[0081] The preparation method of the free radical trapping agent and the preparation method of the flame-retardant master batch for polypropylene in this comparative example are the same as those of Example 1, with the only difference being the components used.

[0082] Comparative Example 3 A flame-retardant master batch for polypropylene, by weight fraction, comprising the following components: 40 parts of polypropylene, 50 parts of a flame retardant and 3 parts of zeolite.

[0083] The flame retardant powder comprises 3 parts of ammonium polyphosphate, 1 part of pentaerythritol and 1 part of melamine.

[0084] In the present comparative example, the preparation method of the flame-retardant powder is to mechanically mix ammonium polyphosphate, pentaerythritol and melamine to obtain the flame-retardant powder.

[0085] The preparation method of the flame-retardant masterbatch of the present comparative example is the same as that of Example 1.

[0086] The polypropylenes obtained in Examples 1-5 and Comparative Examples 1-3 were used to prepare composite samples with the flame-retardant masterbatch as the flame retardant. Specifically, 88wt% of the polypropylene and 12wt% of the flame-retardant masterbatch were uniformly mixed and then poured into a torque rheometer for melt blending to obtain the composite, the temperature of the three zones was 180℃, the mixing time was set to 8min, the rotation speed was 50rpm, and then the composite was hot-pressed into a square sample with a size of 100mm×100mm×3.2mm, the hot-pressing pressure was 15MPa, the temperature was 185℃, and the hot-pressing time was 15min. The square sample was cut into a composite sample strip for testing, and the obtained composite sample strips were denoted as Example 1 group, Example 2 group, Example 3 group, Example 4 group, Example 5 group, Comparative Example 1 group, Comparative Example 2 group, and Comparative Example 3 group, respectively.

[0087] The flame-retardant masterbatch obtained in Comparative Example 3 was used as the flame retardant to prepare a composite sample, and 75wt% of the polypropylene and 25wt% of the flame-retardant masterbatch were used as Comparative Example 4 group.

[0088] The composite sample strips of Example 1-5 group and Comparative Example 1-4 group were tested for limiting oxygen index (LOI) according to the standard GB / T 2406.2-2009, and the limiting oxygen index of the composite sample strips was tested. The sample size was 100mm×6.5mm×3.2mm, and the test results are shown in Table 1.

[0089] The composite sample strips of Example 1-5 group and Comparative Example 1-4 group were tested for vertical burning according to the standard GB / T 2408-2021, and the UL-94 grade of the composite sample strips was tested. The sample size was 100mm×13mm×3.2mm, and the test results are shown in Table 1.

[0090] Table 1 Vertical burning test results and limiting oxygen index test results of the composite sample strips

[0091] ;

[0092] As can be seen from Table 1, the flame-retardant masterbatch of the group of Examples 1-5 has the best flame-retardant effect on polypropylene, the vertical combustion test result UL-94 of the composite sample prepared by the flame-retardant masterbatch of the group of Comparative Example 3 is NR, because the adding amount of the flame-retardant masterbatch of the group of Comparative Example 3 is small, which cannot play a flame-retardant performance, the flame-retardant effect of the composite sample of the group of Comparative Example 4 is also good, which shows that the flame-retardant masterbatch prepared by Comparative Example 3 needs a higher adding amount to achieve a better flame-retardant effect, but the LOI value of the group of Comparative Example 4 is still lower than that of the group of Examples 1-5.

[0093] Compared with the group of Examples 1-5, the flame-retardant effect of the composite sample prepared by the flame-retardant masterbatch of the group of Comparative Example 1 and the group of Comparative Example 2 respectively has different degrees of reduction, and the limiting oxygen index result of the group of Comparative Example 2 is similar to that of the group of Comparative Example 3, which is because the group of Comparative Example 2 does not add TDMC, and the obtained composite sample is extremely flammable.

[0094] The composite samples of the group of Examples 1-5 and the group of Comparative Examples 1-3 are subjected to moisture heat resistance test, specifically, the samples of each group are placed in a 70℃ deionized water environment for moisture heat aging for 168h, and the samples after moisture heat aging are subjected to flame-retardant performance test, and the results are shown in Table 2.

[0095] Table 2 Vertical combustion test results and limiting oxygen index test results of the composite samples after moisture heat aging

[0096] ;

[0097] As can be seen from Table 2, the flame-retardant performance of the composite sample of the group of Examples 1-5 does not have a large decrease, and the LOI of the group of Examples 1-5 and the group of Comparative Example 1 only decreases by about 5%, which shows that the flame-retardant masterbatch prepared by Examples 1-5 has better compatibility with polypropylene and better hydrophobicity, and will not be precipitated under moisture heat state, while the flame-retardant performance of the composite sample of the group of Comparative Example 4 has a large degree of decrease, which is because the flame-retardant masterbatch prepared by Comparative Example 3 is precipitated to a large extent after moisture heat aging in polypropylene, which cannot flame-retardant polypropylene, which shows that the moisture heat resistance of the flame-retardant masterbatch prepared by the present application is higher than that of the existing ammonium polyphosphate intumescent flame retardant.

[0098] The flame-retardant performance of the composite sample of the group of Comparative Example 2 and the group of Comparative Example 3 is similar to that before moisture heat aging, and the flame-retardant performance is always poor.

[0099] The flame-retardant masterbatch prepared by Examples 1 and Comparative Examples 1-3 is subjected to thermal stability test, and the 5% decomposition temperature and the final residual mass percentage of the flame-retardant masterbatch are recorded, and the results are shown in Table 3.

[0100] Table 3 Thermal stability test results of the flame-retardant masterbatch of Examples 1 and Comparative Examples 1-3

[0101] ;

[0102] As can be seen from Table 3, the thermal stability of the flame-retardant master batch of the present application is higher than that of the existing ammonium polyphosphate intumescent flame retardant, and mainly due to the higher thermal stability of the TDMC prepared by the present application; according to the comparison of residual mass percentage, it shows that the char forming performance of the flame-retardant master batch of the present application is better.

[0103] The specific embodiments of the present application described above do not constitute a limitation on the protection scope of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A process for the preparation of a flame retardant masterbatch for polypropylene, characterized in that, Comprise the following steps: S1, after heating and melting tris (2-hydroxyethyl) isocyanurate, add catalyst tetrabutyl titanate and DOPO-DPP to it, stir at 160~165℃ for 3~4h, after the reaction is completed, add melamine and cyanuric acid to it, stir at 190~195℃ for 30min, get viscous melt, then cool, crush to get macromolecular flame retardant TDMC; The preparation method of the DOPO-DPP is: mix diamino diphenyl sulfone, p-formyl benzoic acid and tetrahydrofuran solvent, stir at 50~80℃ for 5~6h under nitrogen atmosphere, after the reaction is completed, cool the reaction liquid to room temperature, add DOPO to it, stir for 12~15h under nitrogen atmosphere, after the reaction is completed, filter, wash the filter cake with tetrahydrofuran for 3 times, dry to get DOPO-DPP; S2, prepare free radical trapping agent by ester exchange reaction of 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1,3,5-triazine and 2,2,6,6-tetramethylpiperidinol; The preparation method of the 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1,3,5-triazine is: S21, mix trichloroisocyanuric acid, chlorobenzene and aluminum chloride, cool to 0~5℃, slowly add benzene to it, stir for 2h, then naturally warm to room temperature, stir for 12h, then warm to 50℃, slowly add resorcinol, then warm to 75~80℃, react for 5h, after the reaction is completed, remove chlorobenzene by azeotropic distillation, then cool to 60℃, filter, dry the precipitate, then recrystallize to get 2,4-diphenyl-6- (2,4-dihydroxyphenyl) -1,3,5-triazine; S22, mix 2,4-diphenyl-6- (2,4-dihydroxyphenyl) -1,3,5-triazine, butyl acetate and potassium carbonate, warm to 60℃, drop chloroacetic acid ethyl ester to it, drop for 2h, react at 60~65℃ for 6h, then warm to 100℃, filter, collect the filtrate, cool to crystallize, collect the solid, dry, then recrystallize to get 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethyloxy) phenyl] -1,3,5-triazine; S3, put 40~50 parts of polypropylene, 50~60 parts of TDMC, 10~15 parts of free radical trapping agent and 3~5 parts of zeolite into a high-speed mixer, stir and mix, then extrude and granulate, get polypropylene flame retardant masterbatch, the extrusion temperature is 150~160℃.

2. The method of preparing a flame-retardant master batch for polypropylene according to claim 1, characterized in that, The molar ratio of the diamino diphenyl sulfone, p-formyl benzoic acid and DOPO is 0.8~1:2:

2.

3. The method of preparing a flame-retardant master batch for polypropylene according to claim 1, characterized in that, The molar ratio of the trichloroisocyanuric acid, benzene and resorcinol is 1:1.95~2:1.1, the molar ratio of the 2,4-diphenyl-6- (2,4-dihydroxyphenyl) -1,3,5-triazine and chloroacetic acid ethyl ester is 1:1.1~1.

2.

4. The process for the preparation of flame retardant masterbatch for polypropylene as claimed in claim 1, wherein, In step S1, the molar ratio of the tris (2-hydroxyethyl) isocyanurate, DOPO-DPP, melamine and cyanuric acid is 1:3:3:

3.

5. The method of preparing a flame-retardant master batch for polypropylene according to claim 1, characterized in that, In step S2, the preparation method of the radical scavenger is specifically as follows: 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1, 3, 5-triazine, 2, 2, 6, 6-tetramethylpiperidinol and a catalyst dibutyl tin oxide are mixed, then a solvent o-dichlorobenzene is added, and the mixture is reacted at 150-155 ℃ for 8 h under nitrogen protection. After the reaction is completed, activated carbon is added for decolorization, and the hot filtrate is crystallized. The collected solid is recrystallized to obtain the radical scavenger.

6. The method of preparing a flame-retardant master batch for polypropylene according to claim 5, characterized in that, The molar ratio of the 2,4-diphenyl-6- [2-hydroxy-4- (ethoxycarbonylmethoxy) phenyl] -1, 3, 5-triazine and 2, 2, 6, 6-tetramethylpiperidinol is 1:1-1.

1.

7. The flame-retardant master batch for polypropylene prepared by the preparation method of claim 1.

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