Composite additive for rotational molding material and preparation method of composite additive

Abstract

The invention belongs to the technical field of compound additives for rotational plastics, and particularly relates to a compound additive for rotational plastics and a preparation method of the compound additive. According to the invention, a migration-resistant filler prepared from a mesoporous molecular sieve loaded light stabilizer, a solubilizer, an antioxidant and a flame retardant are added into polyethylene resin, the mixture is mixed to prepare the composite additive for the rotational molding material, and low-density polyethylene and high-density polyethylene are mixed, so that a resin matrix has high fluidity and molding strength; maleic anhydride grafted polyethylene is used as a solubilizer, so that the flowability of a resin matrix is improved, and the resin matrix has smoke suppression performance; a molecular sieve of the migration-resistant filler can load more light stabilizers, and the molecular sieve is modified by 3-mercaptopropyltriethoxysilane, so that the compatibility and dispersity of the migration-resistant filler in the resin and the migration resistance of the light stabilizers are improved; the prepared composite additive for the rotational molding material is good in compatibility with resin and good in migration resistance, can keep a good durability effect in a plastic product, and has excellent light stability and flame retardance.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite additives for rotational molding plastics, and particularly relates to a composite additive for rotational molding plastics and a preparation method thereof. Background Art

[0002] Rotational molding plastics are plastic materials used in the rotational molding process, which are a type of plastic product with a hollow shape. Polyethylene is the most commonly used raw material for rotational molding plastics. The main technological characteristics of rotational molding are that heating, molding, and cooling are all carried out in a mold without internal pressure, and the processing time is relatively long. This process has extremely high requirements for the fluidity, thermal stability, and weather resistance of the raw materials. In order to reduce the viscoelasticity of the plastic fluid, accelerate the densification process, and improve the bubble removal speed, various functional additives are usually added to the plastic to meet the performance requirements of rotational molding products.

[0003] Chinese invention patent with publication number CN109851901B discloses a cross-linked polyethylene rotational molding plastic for water heater liners, a preparation method thereof, and applications; wherein, the cross-linked polyethylene rotational molding plastic for water heater liners is composed of the following raw materials in parts by weight: 100 parts of polyethylene; 0.1 - 1 part of maleic anhydride; 0.1 - 4 parts of antibacterial agent; 0.1 - 1 part of peroxide cross-linking agent; 0.1 - 1 part of cross-linking assistant; 0.3 - 0.5 part of antioxidant; 0.2 - 1 part of lubricant; wherein, the polyethylene is a mixture of linear low-density polyethylene and metallocene polyethylene, and the ratio of the two is 1 - 9:1; the melt index of the polyethylene is 10 - 30 g / 10 min. Compared with the prior art, the cross-linked polyethylene rotational molding plastic for water heater liners provided by this invention has good adhesion between the plastic inner layer and the metal layer of the obtained water heater liner, a smooth inner surface of the plastic inner layer, and convenient processing, and can reduce production costs. However, the prior art has the technical problem that the filler component of the rotational molding plastic additive has not been further modified to improve the migration resistance and compatibility of the additive. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite additive for rotational molding plastics and a preparation method thereof, which are used to solve the technical problem in the prior art that the filler component of the rotational molding plastic additive has not been further modified to improve the migration resistance and compatibility of the additive.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: A composite additive for rotational molding plastics is prepared from the following components in parts by mass: 50 - 60 parts of polyethylene resin, 3 - 5 parts of solubilizer, 4 - 6 parts of 8# premix, 26 - 32 parts of migration-resistant filler, 8 - 12 parts of antioxidant, and 20 - 25 parts of flame retardant.

[0006] The polyethylene resin is prepared by mixing low-density polyethylene and high-density polyethylene in a mass ratio of 2-3:7-8; the solubilizer is maleic anhydride grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is any one of magnesium hydroxide powder and ammonium polyphosphate.

[0007] A preparation method of a composite additive for rolling plastics comprises the following steps: S1. Mix the polyethylene resin, 8# premix, solubilizer, migration-resistant filler, antioxidant and flame retardant evenly, add them into an extruder for hot pressing and extrusion, cool with water and then pelletize with a pelletizer to obtain a crude additive. S2. Re-pelletize the crude additive and sieve it to obtain a composite additive for rolling plastics.

[0008] Preferably, the temperature settings of each temperature zone in the hot pressing and extrusion in S1 are as follows: the head temperature is 160-180 °C, the first zone is 140-150 °C, the second zone is 150-170 °C, the third zone is 170-190 °C, the fourth zone is 170-190 °C, and the fifth zone is 160-180 °C.

[0009] Preferably, in S2, the re-pelletizing is carried out until 90% of the powder passes through a 100-200 mesh sieve.

[0010] Preferably, the preparation method of the migration-resistant filler comprises the following steps: S11. By mass, add 14-15 parts of an aluminum source into 30-40 parts of deionized water, add 60-70 parts of a 25 wt% aqueous solution of tetrabutylammonium hydroxide, dropwise add a silicon source under stirring, stir evenly and then add 40-50 parts of a polyethylene glycol template agent, crystallize, filter and collect the solid, dry and grind it, and then calcine it to obtain a mesoporous molecular sieve. S12. By mass, add 10-15 parts of the mesoporous molecular sieve into 50-100 parts of toluene, add 4-5 parts of 3-mercaptopropyltriethoxysilane in a nitrogen atmosphere and heat up to react, dry it and then put it into 50-100 parts of deionized water, add 5-10 parts of a grafted light stabilizer and 0.05-0.3 parts of an azobisisobutyronitrile initiator to react, filter and collect the solid, and dry it to obtain the migration-resistant filler.

[0011] Preferably, in S11, the aluminum source is any one of aluminum sulfate and sodium aluminate, the silicon source is any one of sodium silicate and tetraethyl orthosilicate, the silicon-aluminum molar ratio in the aluminum source and the silicon source is controlled to be 2-3, while dropping the silicon source, the pH of the system is adjusted to 9.5-10.5 with a sodium hydroxide solution, and after adding polyethylene glycol, the temperature is raised to 90-100 °C for crystallization for 20-24 h.

[0012] Preferably, in S11, it is calcined at 500-600 °C for 2-3 h.

[0013] Preferably, after adding 3-mercaptopropyltriethoxysilane in S12, the temperature is raised to 90-100°C and reacted for 18-24 h, and after adding an initiator, the temperature is raised to 60-65°C and reacted for 12-18 h.

[0014] Preferably, the preparation method of the grafted light stabilizer includes the following steps: S21: By mass, add 20-30 parts of 4,4'-dihydroxybenzophenone to a reaction kettle, add 10-15 parts of triethylamine and 40-50 parts of dichloromethane, and dropwise add 10-20 parts of methacryloyl chloride under a nitrogen atmosphere for reaction. After the reaction is completed, filter to remove the precipitate, wash successively with hydrochloric acid, sodium hydroxide aqueous solution and deionized water, and then remove water by rotary evaporation to obtain Intermediate 1; S22: By mass, add 20-30 parts of Intermediate 1 and 40-50 parts of N,N-dimethylformamide to a reaction kettle, add 3-5 parts of phosphorus oxychloride for reaction, neutralize and purify to obtain the grafted light stabilizer.

[0015] Preferably, the reaction principle of the grafted light stabilizer is as follows:

[0016] Intermediate 1 was detected and analyzed by mass spectrometry, and the results were as follows: m / z: 282.09 (100.0%), 283.09 (18.5%), 284.10 (1.6%).

[0017] The grafted light stabilizer was detected and analyzed by mass spectrometry, and the results were as follows: m / z: 308.10 (100.0%), 309.11 (20.9%), 310.11 (2.9%).

[0018] Preferably, in S21, the reaction is carried out at 0-5°C for 3-4 h, the water is removed with anhydrous sodium sulfate for 10-12 h, and then the solvent is removed by rotary evaporation.

[0019] Preferably, after adding phosphorus oxychloride in S22, the temperature is raised to 70-80°C and reacted for 3-4 h, neutralized to neutral with saturated sodium carbonate solution, then washed with deionized water, vacuum dried and then added to ethanol and heated to 40-50°C for recrystallization and purification.

[0020] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are: The present invention uses a resin matrix composed of a mixture of low-density polyethylene and high-density polyethylene, adds a migration-resistant filler prepared by loading a light stabilizer on mesoporous molecular sieve, maleic anhydride-grafted polyethylene as a solubilizer, a mixed antioxidant and a flame retardant to prepare a composite additive for rotational molding plastics. The mixture of low-density polyethylene and high-density polyethylene endows the resin matrix with high fluidity and molding strength, and can improve the impact resistance of rotational molding plastics when applied to the preparation of rotational molding plastics; maleic anhydride-grafted polyethylene can act as a lubricating layer at the interface, improve the fluidity of the migration-resistant filler and the flame retardant in the resin matrix, and has a smoke suppression performance; the molecular sieve of the migration-resistant filler has a mesoporous structure, can load more light stabilizers, and has a flame retardant property. The molecular sieve modified by 3-mercaptopropyltriethoxysilane improves the compatibility and dispersibility of the migration-resistant filler in the polyethylene matrix, and can form a covalent bond with the grafted light stabilizer, improving the migration resistance of the light stabilizer; the composite additive for rotational molding plastics prepared by the present invention has good compatibility and migration resistance with resins such as polyolefins, can maintain good durability effects in plastic products, and has excellent light stability and flame retardant properties.

[0021] The present invention prepares mesoporous molecular sieve using polyethylene glycol as a template agent, then modifies it with 3-mercaptopropyltriethoxysilane, and loads the grafted light stabilizer onto the mesoporous molecular sieve through thiol-ene click reaction, and then performs surface modification with sodium dodecyl sulfate to obtain the migration-resistant filler; polyethylene glycol as a template agent can endow the mesoporous structure with a uniform pore size, can load more light stabilizers and ensure the uniform dispersion of the light stabilizers; the modification of the molecular sieve surface with 3-mercaptopropyltriethoxysilane can improve the compatibility and dispersibility of the molecular sieve in the resin.

[0022] After reacting 4,4'-dihydroxybenzophenone with methacryloyl chloride to graft a methacryloyl group, and then converting the alcohol group to an aldehyde group through a reaction with phosphorus oxychloride, the finally prepared grafted light stabilizer can be loaded into the mesoporous molecular sieve through thiol-ene click reaction and has excellent migration resistance. Detailed Embodiments

[0023] The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] The model of the low-density polyethylene involved in the embodiments of the present invention is LLDPE DNDA8320, the model of the high-density polyethylene is HDPE 8007, and the model of the maleic anhydride-grafted polyethylene is 41E710.

[0025] Example 1. A composite additive for rolling plastics is prepared from components with the following masses: 50 g of polyethylene resin, 5 g of solubilizer, 6 g of #8 premix, 26 g of migration-resistant filler, 8 g of antioxidant, and 20 g of flame retardant.

[0026] The polyethylene resin is prepared by mixing low-density polyethylene and high-density polyethylene in a mass ratio of 2:8; the solubilizer is maleic anhydride-grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is magnesium hydroxide powder.

[0027] The preparation method of the migration-resistant filler in this example includes the following steps: S11. Add 14 g of aluminum sulfate to 30 g of deionized water, add 60 g of 25 wt% tetrabutylammonium hydroxide aqueous solution, dropwise add 35 g of silicon source tetraethyl orthosilicate under stirring, and adjust the pH of the system to 10 with sodium hydroxide solution while stirring evenly. Then add 40 g of polyethylene glycol-2000, heat up to 100 °C for crystallization for 24 h, filter to collect the solid, dry and grind it, and then calcine to obtain mesoporous molecular sieve; S12. Add 15 g of mesoporous molecular sieve to 100 g of toluene, add 5 g of 3-mercaptopropyltriethoxysilane under nitrogen atmosphere, heat up to 100 °C and react for 24 h. After drying, put it into 100 g of deionized water, add 10 g of grafted light stabilizer and 0.3 g of azobisisobutyronitrile initiator, heat up to 65 °C and react for 18 h, filter to collect the solid, and dry to obtain the migration-resistant filler.

[0028] The preparation method of the grafted light stabilizer in this example includes the following steps: S21. Add 21 g of 4,4'-dihydroxybenzophenone to the reaction kettle, add 10 g of triethylamine and 50 g of dichloromethane, dropwise add 10 g of methacryloyl chloride under nitrogen atmosphere, react at 0 °C for 3 h. After the reaction is completed, filter to remove the precipitate, wash it successively with 10 wt% hydrochloric acid, 20 wt% sodium hydroxide aqueous solution and deionized water, remove water with anhydrous sodium sulfate for 12 h, and then rotary evaporate to remove the solvent to obtain intermediate 1; S22. Add 25 g of intermediate 1 and 40 g of N,N-dimethylformamide to the reaction kettle, add 5 g of phosphorus oxychloride, heat up to 80 °C and react for 4 h. Neutralize it to neutral with saturated sodium carbonate solution, then wash it with deionized water, vacuum dry it, add it to ethanol, heat up to 50 °C for recrystallization and purification to obtain the grafted light stabilizer.

[0029] The preparation method of a composite additive for rolling plastics in this example includes the following steps: S1. Mix polyethylene resin, 8# premix, solubilizer, migration-resistant filler, antioxidant, and flame retardant evenly, add them to an extruder for hot pressing and extrusion. The temperature settings for each temperature zone during hot pressing and extrusion are as follows: the head temperature is 160 °C, the first zone is 140 °C, the second zone is 150 °C, the third zone is 170 °C, the fourth zone is 190 °C, the fifth zone is 180 °C. After water cooling, granulate with a granulator to obtain the crude auxiliary agent. S2. Re-granulate the crude auxiliary agent until 90% of the powder passes through a 100-mesh sieve to obtain a composite auxiliary agent for rotational molding plastics.

[0030] Example 2. A composite auxiliary agent for rotational molding plastics in this example is prepared from the following components by mass: 55 g of polyethylene resin, 3 g of solubilizer, 4.5 g of 8# premix, 28 g of migration-resistant filler, 8 g of antioxidant, and 20 g of flame retardant.

[0031] The polyethylene resin is prepared by mixing low-density polyethylene and high-density polyethylene in a mass ratio of 3:7; the solubilizer is maleic anhydride-grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is ammonium polyphosphate.

[0032] The preparation method of the migration-resistant filler in this example includes the following steps: S11. Add 14.5 g of aluminum source aluminum sulfate to 40 g of deionized water, add 70 g of 25 wt% tetrabutylammonium hydroxide aqueous solution, dropwise add 30 g of silicon source sodium silicate under stirring, and adjust the pH of the system to 9.5 with sodium hydroxide solution. Stir evenly and then add 50 g of polyethylene glycol-2000. Heat up to 90 °C for crystallization for 20 h, filter to collect the solid, dry and grind it, and then calcine it to obtain mesoporous molecular sieve. S12. Add 10 g of mesoporous molecular sieve to 50 g of toluene, add 4 g of 3-mercaptopropyltriethoxysilane under a nitrogen atmosphere, heat up to 100 °C and react for 18 h. After drying, put it into 50 g of deionized water, add 5 g of grafted light stabilizer and 0.05 g of azobisisobutyronitrile initiator, heat up to 60 °C and react for 18 h. Filter to collect the solid and dry it to obtain the migration-resistant filler.

[0033] The preparation method of the grafted light stabilizer in this example includes the following steps: S21. Add 25 g of 4,4'-dihydroxybenzophenone to a reaction kettle, add 13 g of triethylamine and 50 g of dichloromethane, dropwise add 15 g of methacryloyl chloride under a nitrogen atmosphere, and react at 5 °C for 4 h. After the reaction is completed, filter to remove the precipitate, wash it successively with 10 wt% hydrochloric acid, 20 wt% sodium hydroxide aqueous solution and deionized water, remove water with anhydrous sodium sulfate for 12 h, and then rotary evaporate to remove the solvent to obtain Intermediate 1. S22. Add 20 g of intermediate 1 and 50 g of N,N-dimethylformamide into a reaction kettle, add 5 g of phosphorus oxychloride, heat up to 70 °C and react for 3 h. After neutralizing to neutral with saturated sodium carbonate solution, wash with deionized water, vacuum dry, and then add to ethanol, heat up to 40 - 50 °C for recrystallization purification to obtain the grafted light stabilizer.

[0034] A preparation method of a composite auxiliary agent for rolling plastics in this embodiment includes the following steps: S1. Mix polyethylene resin, 8# premix, solubilizer, migration-resistant filler, antioxidant, and flame retardant evenly, add them into an extruder for hot pressing and extrusion. The temperature settings of each temperature zone for hot pressing and extrusion are as follows: the head temperature is 165 °C, the first zone is 145 °C, the second zone is 160 °C, the third zone is 180 °C, the fourth zone is 180 °C, the fifth zone is 160 °C. After water cooling, granulate with a granulator to obtain the crude auxiliary agent. S2. Re-granulate the crude auxiliary agent until 90% of the powder passes through a 200-mesh sieve to obtain a composite auxiliary agent for rolling plastics.

[0035] Example 3. A composite auxiliary agent for rolling plastics in this embodiment is prepared from the following components by mass: 58 g of polyethylene resin, 3 g of solubilizer, 5 g of 8# premix, 30 g of migration-resistant filler, 12 g of antioxidant, and 25 g of flame retardant.

[0036] The polyethylene resin is prepared by mixing low-density polyethylene and high-density polyethylene in a mass ratio of 2.5:7.5; the solubilizer is maleic anhydride-grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is prepared by mixing magnesium hydroxide powder and ammonium polyphosphate in a mass ratio of 1:1.

[0037] The preparation method of the migration-resistant filler in this embodiment includes the following steps: S11. Add 15 g of aluminum source sodium aluminate into 40 g of deionized water, add 70 g of 25 wt% tetrabutylammonium hydroxide aqueous solution, dropwise add 75 g of silicon source tetraethyl orthosilicate under stirring, and at the same time adjust the pH of the system to 10.5 with sodium hydroxide solution, stir evenly, then add 50 g of polyethylene glycol-2000, heat up to 95 °C for crystallization for 24 h, filter to collect the solid, dry and grind, and then calcine to obtain mesoporous molecular sieve. S12. Add 15 g of mesoporous molecular sieve into 100 g of toluene, add 5 g of 3-mercaptopropyltriethoxysilane under nitrogen atmosphere, heat up to 100 °C and react for 18 h, dry, then put it into 100 g of deionized water, add 10 g of grafted light stabilizer and 0.05 g of azobisisobutyronitrile initiator, heat up to 65 °C and react for 12 h, filter to collect the solid, and dry to obtain the migration-resistant filler.

[0038] The preparation method of the grafted light stabilizer in this embodiment includes the following steps: S21. Add 28 g of 4,4'-dihydroxybenzophenone into the reaction kettle, add 13 g of triethylamine and 45 g of dichloromethane, dropwise add 20 g of methacryloyl chloride under a nitrogen atmosphere, react at 0 °C for 3.5 h. After the reaction is completed, filter to remove the precipitate, wash successively with 10 wt% hydrochloric acid, 20 wt% sodium hydroxide aqueous solution and deionized water, remove water with anhydrous sodium sulfate for 10 h, and then rotary evaporate to remove the solvent to obtain Intermediate 1. S22. Add 25 g of Intermediate 1 and 45 g of N,N-dimethylformamide into the reaction kettle, add 3 g of phosphorus oxychloride, heat up to 70 °C and react for 3 h. Neutralize to neutral with saturated sodium carbonate solution, then wash with deionized water, vacuum dry, add to ethanol, heat up to 45 °C for recrystallization and purification to obtain the grafted light stabilizer.

[0039] The preparation method of a composite additive for rolling plastics in this embodiment includes the following steps: S1. Mix polyethylene resin, 8# premix, solubilizer, migration-resistant filler, antioxidant and flame retardant evenly, add them into an extruder for hot pressing and extrusion. The temperature settings of each temperature zone for hot pressing and extrusion are: the head temperature is 180 °C, the first zone is 150 °C, the second zone is 170 °C, the third zone is 190 °C, the fourth zone is 190 °C, the fifth zone is 180 °C. After water cooling, granulate with a granulator to obtain the crude additive. S2. Re-granulate the crude additive until 90% of the powder passes through a 160-mesh sieve to obtain a composite additive for rolling plastics.

[0040] Example 4. A composite additive for rolling plastics in this embodiment is prepared from the following components by mass: 60 g of polyethylene resin, 5 g of solubilizer, 5.5 g of 8# premix, 32 g of migration-resistant filler, 12 g of antioxidant and 20 g of flame retardant.

[0041] The polyethylene resin is prepared by mixing low-density polyethylene and high-density polyethylene in a mass ratio of 3:7; the solubilizer is maleic anhydride-grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is magnesium hydroxide powder.

[0042] The preparation method of the migration-resistant filler in this embodiment includes the following steps: S11. Add 14 g of the aluminum source sodium aluminate into 40 g of deionized water, add 65 g of 25 wt% tetrabutylammonium hydroxide aqueous solution, dropwise add 45 g of the silicon source sodium silicate under stirring, and at the same time adjust the pH of the system to 10.5 with sodium hydroxide solution, stir evenly, then add 40 g of polyethylene glycol-2000, heat up to 100 °C for crystallization for 20 h, filter to collect the solid, dry and grind, and then calcine to obtain mesoporous molecular sieve. S12. Add 10 g of mesoporous molecular sieve to 100 g of toluene, add 5 g of 3-mercaptopropyltriethoxysilane in a nitrogen atmosphere, heat up to 90 °C and react for 20 h. After drying, put it into 100 g of deionized water, add 10 g of grafted light stabilizer and 0.1 g of azobisisobutyronitrile initiator, heat up to 65 °C and react for 18 h. Filter and collect the solid, and dry it to obtain the migration-resistant filler.

[0043] The preparation method of the grafted light stabilizer in this example includes the following steps: S21. Add 30 g of 4,4'-dihydroxybenzophenone to the reaction kettle, add 15 g of triethylamine and 50 g of dichloromethane. Dropwise add 20 g of methacryloyl chloride under a nitrogen atmosphere and react at 5 °C for 4 h. After the reaction is completed, filter to remove the precipitate, wash it successively with 10 wt% hydrochloric acid, 20 wt% sodium hydroxide aqueous solution and deionized water, dehydrate it with anhydrous sodium sulfate for 12 h, and then rotary evaporate to remove the solvent to obtain Intermediate 1; S22. Add 30 g of Intermediate 1 and 50 g of N,N-dimethylformamide to the reaction kettle, add 5 g of phosphorus oxychloride, heat up to 80 °C and react for 4 h. Neutralize it to neutral with saturated sodium carbonate solution, then wash it with deionized water, vacuum dry it, add it to ethanol, heat up to 50 °C for recrystallization and purification to obtain the grafted light stabilizer.

[0044] The preparation method of a composite additive for rotational molding in this example includes the following steps: S1. Mix polyethylene resin, No. 8 premix, solubilizer, migration-resistant filler, antioxidant and flame retardant evenly, add them to an extruder for hot pressing and extrusion. The temperature settings of each temperature zone for hot pressing and extrusion are: the head temperature is 160 °C, the first zone is 140 °C, the second zone is 150 °C, the third zone is 170 °C, the fourth zone is 170 °C, the fifth zone is 160 °C. After water cooling, granulate it with a granulator to obtain the crude additive; S2. Granulate the crude additive for the second time until 90% of the powder passes through a 200-mesh sieve to obtain a composite additive for rotational molding.

[0045] Comparative Example 1. The difference between this comparative example and Example 1 is that the migration-resistant filler is replaced with bentonite.

[0046] Comparative Example 2. The difference between this comparative example and Example 1 is that no solubilizer is added.

[0047] Comparative Example 3. The difference between this comparative example and Example 1 is that 3-mercaptopropyltriethoxysilane is replaced with KH-550.

[0048] Performance test Mix the composite additives prepared in each example and comparative example with polyethylene powder at a mass ratio of 5:100, and perform rotational molding to obtain samples.

[0049] The tensile strength and elongation at break of the samples prepared in each example and comparative example were measured according to GB / T 1040.1-2018 Plastics - Determination of tensile properties.

[0050] The Izod impact strength of the samples prepared in each example and comparative example was measured according to GB / T 1843-2008 Plastics - Determination of Izod impact strength.

[0051] According to GB / T 3682.1-2018 Plastics - Determination of melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics, after the composite additives and polyethylene powder prepared in each example and comparative example were mixed at a mass ratio of 5:100, the melt flow rate of each example and comparative example was measured at 190 °C under a load of 5 kg.

[0052] The flame retardant grade of the samples prepared in each example and comparative example was measured according to GB / T 2408-2008 Plastics - Determination of burning behaviour - Horizontal and vertical methods.

[0053] According to the test method of EN 13130-1:2004, 1 g of the samples prepared in each example and comparative example was immersed in 200 mL of isooctane, extracted at 20 °C for 1 d, 1 mL of the extract was taken, and the content of the light stabilizer in the extract was detected by liquid chromatography. The migration resistance was calculated according to the following formula:

[0054] γ is the retention rate of the light stabilizer, in %; C0 is the mass of the light stabilizer contained in 1 g of the sample, in mg; C1 is the mass of the light stabilizer in the extract, in mg.

[0055] The test results are shown in Table 1: Table 1 Test results

[0056] From the data in the above table, it can be seen that the tensile strength of the samples prepared by rotational moulding using the composite additives prepared in Examples 1 to 4 is between 16.5 and 17.9 MPa, and the elongation at break is between 165.1 and 169.3%. In Comparative Example 2, no solubilizer was added, so the compatibility between the filler, flame retardant and resin matrix became poor, resulting in a tensile strength of 14.3 MPa and an elongation at break of 152.8%. This shows that the rotational moulding plastics prepared by using the composite additives of the present invention have excellent mechanical properties; the Izod impact strength of the samples prepared by rotational moulding using the composite additives prepared in Examples 1 to 4 is 30 - 34 kJ / m 2Among them, it shows that the composite auxiliary agent prepared by the present invention can endow the rotomolding plastics with excellent impact resistance when used in rotomolding; the melt flow rate of the samples prepared by using the composite auxiliary agents prepared in Examples 1-4 in rotomolding is 20-21 g / 10 min, indicating that the composite auxiliary agent prepared by the present invention has excellent flow performance; the flame retardant grade of the samples prepared by using the composite auxiliary agents prepared in Examples 1-4 in rotomolding is UV-0, indicating that the composite auxiliary agent prepared by the present invention has excellent flame retardant performance; the retention rate of the light stabilizer of the samples prepared by using the composite auxiliary agents prepared in Examples 1-4 in rotomolding is 87-89%, indicating that the composite auxiliary agent prepared by the present invention has excellent migration resistance.

[0057] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

[0058] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A composite auxiliary agent for rolling plastics, characterized in that, Prepared from the following components in parts by mass: 50 - 60 parts of polyethylene resin, 3 - 5 parts of solubilizer, 4 - 6 parts of 8# premix, 26 - 32 parts of migration - resistant filler, 8 - 12 parts of antioxidant, and 20 - 25 parts of flame retardant.

2. The composite auxiliary agent for rolling plastics according to claim 1, wherein, The polyethylene resin is prepared by mixing low - density polyethylene and high - density polyethylene in a mass ratio of 2 - 3:7 - 8; the solubilizer is maleic anhydride - grafted polyethylene; the antioxidant is prepared by mixing antioxidant 168 and antioxidant 1076 in a mass ratio of 1:1; the flame retardant is any one of magnesium hydroxide powder and ammonium polyphosphate.

3. A composite auxiliary agent for rolling plastics according to claim 1, characterized in that, The preparation method of the migration - resistant filler includes the following steps: S11: By mass, add 14 - 15 parts of aluminum source to 30 - 40 parts of deionized water, add 60 - 70 parts of 25wt% tetrabutylammonium hydroxide aqueous solution, drop - wise add the silicon source under stirring, stir evenly and then add 40 - 50 parts of polyethylene glycol template agent, crystallize, filter and collect the solid, dry and grind it, and then calcine to obtain mesoporous molecular sieve; S12: By mass, add 10 - 15 parts of mesoporous molecular sieve to 50 - 100 parts of toluene, add 4 - 5 parts of 3 - mercaptopropyltriethoxysilane in a nitrogen atmosphere and heat up to react, dry and then put it into 50 - 100 parts of deionized water, add 5 - 10 parts of grafted light stabilizer and 0.05 - 0.3 parts of azobisisobutyronitrile initiator to react, filter and collect the solid, dry to obtain the migration - resistant filler.

4. The composite auxiliary agent for rolling plastics according to claim 3, characterized in that, In S11, the aluminum source is any one of aluminum sulfate and sodium aluminate, the silicon source is any one of sodium silicate and tetraethyl orthosilicate, control the silicon - aluminum molar ratio in the aluminum source and the silicon source to be 2 - 3, while dropping the silicon source, adjust the pH of the system to 9.5 - 10.5 with sodium hydroxide solution, and heat up to 90 - 100 °C for crystallization for 20 - 24 h after adding polyethylene glycol.

5. The composite auxiliary agent for rolling plastics according to claim 3, characterized in that, In S11, calcine at 500 - 600 °C for 2 - 3 h; in S12, heat up to 90 - 100 °C to react for 18 - 24 h after adding 3 - mercaptopropyltriethoxysilane, and heat up to 60 - 65 °C to react for 12 - 18 h after adding the initiator.

6. The composite auxiliary agent for rolling plastics according to claim 3, characterized in that, The preparation method of the grafted light stabilizer includes the following steps: S21: By mass, add 20 - 30 parts of 4,4’ - dihydroxybenzophenone to the reaction kettle, add 10 - 15 parts of triethylamine and 40 - 50 parts of dichloromethane, drop - wise add 10 - 20 parts of methacryloyl chloride in a nitrogen atmosphere to react, after the reaction is completed, filter to remove the precipitate, wash it successively with hydrochloric acid, sodium hydroxide aqueous solution and deionized water, and then remove water by rotary evaporation to obtain intermediate 1; S22: By mass, add 20 - 30 parts of intermediate 1 and 40 - 50 parts of N,N - dimethylformamide to the reaction kettle, add 3 - 5 parts of phosphorus oxychloride to react, neutralize and purify to obtain the grafted light stabilizer.

7. A composite auxiliary agent for rolling plastics according to claim 6, characterized in that, In S21, the reaction is carried out at 0 - 5°C for 3 - 4 h, water is removed with anhydrous sodium sulfate for 10 - 12 h, and then the solvent is removed by rotary evaporation; in S22, after adding phosphorus oxychloride, the temperature is raised to 70 - 80°C and the reaction is carried out for 3 - 4 h. After neutralizing to neutral with saturated sodium carbonate solution, it is washed with deionized water, vacuum dried, and then added to ethanol and heated to 40 - 50°C for recrystallization purification.

8. A preparation method of a composite auxiliary agent for rolling plastics, characterized in that, It includes the following steps: S1. Polyethylene resin, 8# premix, solubilizer, migration-resistant filler, antioxidant and flame retardant are mixed evenly, added to an extruder for hot pressing and extrusion, water-cooled, and then granulated with a granulator to obtain crude auxiliary materials. S2. The crude auxiliary materials are granulated for the second time and sieved to obtain a composite auxiliary agent for rolling plastics.

9. The preparation method of a composite auxiliary agent for rolling plastics according to claim 8, characterized in that, In S1, the temperature settings of each temperature zone for hot pressing and extrusion are as follows: the head temperature is 160 - 180°C, the first zone is 140 - 150°C, the second zone is 150 - 170°C, the third zone is 170 - 190°C, the fourth zone is 170 - 190°C, and the fifth zone is 160 - 180°C; in S2, the second granulation is carried out until 90% of the powder passes through a 100 - 200 mesh sieve.

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