A highly dispersed magnesium hydroxide flame-retardant master batch, a preparation method thereof and a halogen-free flame-retardant polyolefin composite

Abstract

The application belongs to the technical field of polymer material functional additives, and particularly relates to a high-dispersion magnesium hydroxide flame-retardant master batch, a preparation method thereof and a halogen-free flame-retardant polyolefin composite material. The surface modification of magnesium hydroxide powder is realized by grading coating of a composite modifier, a compatible toughening agent and a synergistic flame retardant are matched for synergistic design, and a melting blending-dense mixing-granulation process is combined to prepare the flame-retardant master batch which has good dispersity, high flame-retardant efficiency and excellent compatibility with polyolefin resin, realizes good flame-retardant effect under low filling amount, and meanwhile maintains the mechanical properties and processing performance of the composite material.

Description

Technical Field

[0001] This invention belongs to the field of functional additives for polymer materials, specifically relating to a highly dispersed magnesium hydroxide flame retardant masterbatch and its preparation method, and a halogen-free flame retardant polyolefin composite material. Background Technology

[0002] Magnesium hydroxide, as a halogen-free, low-smoke, and environmentally friendly inorganic flame retardant, is widely used in the flame-retardant modification of polyolefin plastics such as PP, PE, and EVA due to its advantages such as good thermal stability, excellent smoke suppression effect, and low toxicity. However, magnesium hydroxide is a polar inorganic powder with poor compatibility with non-polar polymer resins. Direct addition can easily lead to agglomeration and uneven dispersion, resulting in a significant decrease in the mechanical properties of the composite material. At the same time, magnesium hydroxide has a relatively low flame-retardant efficiency, requiring a high filler content to achieve the ideal flame-retardant effect, which further exacerbates the problems of reduced material toughness and deteriorated processing performance.

[0003] Existing magnesium hydroxide flame retardant masterbatches are mostly prepared using a single coupling agent modification and simple physical mixing method, which suffers from technical drawbacks such as insufficient powder dispersibility, difficulty in achieving both flame retardancy and mechanical properties, and poor masterbatch flowability. Some technologies improve mechanical properties by adding elastomer toughening agents, but insufficient synergistic design between toughening agents and flame retardants easily leads to a decrease in flame retardant effect; other technologies use composite modifiers to improve compatibility, but the modification process is cumbersome, parameters are not properly controlled, and the surface of magnesium hydroxide is not fully coated, resulting in agglomeration.

[0004] To address the aforementioned issues, a magnesium hydroxide flame-retardant masterbatch with high dispersion, low filler content, and synergistic optimization of flame retardant and mechanical properties was developed. Through precise surface modification of powder, synergistic compounding of additives, and precise process control, the industry challenges of uneven dispersion of magnesium hydroxide in resin and material embrittlement caused by high filler content were solved. This is key to promoting the industrial application of halogen-free flame-retardant polyolefin materials. Summary of the Invention

[0005] The purpose of this invention is to provide a highly dispersed magnesium hydroxide flame retardant masterbatch and its preparation method, as well as a halogen-free flame retardant polyolefin composite material. This invention achieves surface modification of magnesium hydroxide powder through graded coating with a composite modifier, and obtains a flame retardant masterbatch with good dispersibility, high flame retardant efficiency, and excellent compatibility with polyolefin resin by synergistic design with a compatible toughening agent and a synergistic flame retardant. It achieves good flame retardant effect with low filler content, while maintaining the mechanical properties and processing properties of the composite material.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a highly dispersed magnesium hydroxide flame retardant masterbatch, comprising the following raw materials in parts by weight: 60-75 parts magnesium hydroxide, 15-25 parts carrier resin, 2-5 parts modifier, 3-8 parts compatibility toughening agent, 1-3 parts synergistic flame retardant, and 0.5-2 parts dispersing lubricant. The magnesium hydroxide includes nano-magnesium hydroxide and micron-sized magnesium hydroxide; The modifiers include silane coupling agents and titanate coupling agents.

[0007] Preferably, the nano-magnesium hydroxide has a D50 of 50-100 nm and a purity of ≥99%. The micron-sized magnesium hydroxide has a D50 of 2~5μm, a purity ≥98%, and a specific surface area of ​​10~20m². 2 / g.

[0008] Preferably, the mass ratio of the nano-magnesium hydroxide to the micron-magnesium hydroxide is 1:3~5.

[0009] Preferably, the silane coupling agent includes at least one of KH-550 and KH-560; The titanate coupling agent includes at least one of NDZ-101 and NDZ-201; The mass ratio of the silane coupling agent to the titanate coupling agent is 1:2~3.

[0010] Preferably, the carrier resin includes at least one of EVA resin and PP wax; the EVA resin has a VA content of 18-28% and a melt index of 5-15 g / 10 min; The compatibility toughening agent includes at least one of maleic anhydride-grafted POE and maleic anhydride-grafted EVA, with a grafting rate ≥0.8%; The synergistic flame retardant includes at least one of zinc borate, zinc molybdate, and nano-silica. The dispersing lubricant includes at least one of zinc stearate, polyethylene wax, and erucamide.

[0011] This invention also provides a method for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch described in the above technical solution, comprising the following steps: Magnesium hydroxide was modified by coating it with silane coupling agent and titanate coupling agent in sequence to obtain modified magnesium hydroxide. A carrier resin, a compatibility toughening agent, a synergistic flame retardant, and a dispersing lubricant are added to the modified magnesium hydroxide and premixed to obtain a premix; The premixed material is melt-kneaded to obtain the melt-kneaded material; The molten material is extruded and granulated to obtain the highly dispersed magnesium hydroxide flame retardant masterbatch.

[0012] Preferably, the premixing speed is 800~1000 rpm and the time is 15~25 min; The melting and mixing temperature is 120~150℃, the rotation speed is 60~80rpm, and the time is 8~12min.

[0013] Preferably, the extrusion granulation is performed using a twin-screw extruder; The twin-screw extruder includes three temperature zones: the first temperature zone has a temperature of 110~120℃, the second temperature zone has a temperature of 130~140℃, the third temperature zone has a temperature of 140~150℃, and the die head temperature has a temperature of 145~155℃; the screw speed is 200~260rpm.

[0014] The present invention also provides a halogen-free flame-retardant polyolefin composite material, comprising polyolefin and a flame retardant, wherein the flame retardant is the highly dispersed magnesium hydroxide flame-retardant masterbatch described in the above technical solution or the highly dispersed magnesium hydroxide flame-retardant masterbatch prepared by the preparation method described in the above technical solution.

[0015] Preferably, the polyolefin includes at least one of PP, PE and EVA; The flame retardant content of the halogen-free flame-retardant polyolefin composite material is 15-30% by mass.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) Micro-nano compounding + graded coating, greatly improving dispersibility: Nano and micro magnesium hydroxide micro-nano compounding is adopted to balance flame retardant efficiency and processing performance; through graded coating of silane-titanium ester composite modifier, the powder surface is fully modified, the polarity difference is greatly reduced, the agglomeration problem of magnesium hydroxide in resin is solved, and the dispersion uniformity of masterbatch is improved.

[0017] (2) Flame retardant-toughening synergistic design, with performance in balance: The compatibility toughening agent is a maleic anhydride grafted modified elastomer, which not only improves the interfacial compatibility between the masterbatch and the resin, but also compensates for the decrease in material toughness caused by magnesium hydroxide filling; the synergistic flame retardant works with magnesium hydroxide to achieve high flame retardancy at low filling amount, avoiding the mechanical property decay caused by high filling.

[0018] (3) Precise process control and excellent processing performance: The combination process of "high-speed mixing-internal mixing-twin-screw extrusion" is adopted. The internal mixing process achieves full integration of materials, and the twin-screw extrusion precisely controls the temperature to ensure the melt flowability and particle uniformity of the masterbatch. It is suitable for various processing technologies of polyolefin resins and has no problems such as machine blockage or uneven plasticization.

[0019] (4) Environmentally friendly and halogen-free with a wide range of applications: All raw materials are halogen-free and environmentally friendly, and comply with environmental standards such as RoHS and REACH. They can be widely used in the flame retardant modification of polyolefin plastics in fields such as wires and cables, auto parts, packaging materials, and building profiles, and have broad industrialization prospects. Attached Figure Description

[0020] Figure 1 This is a photograph of the highly dispersed magnesium hydroxide flame retardant masterbatch obtained in Example 1. Detailed Implementation

[0021] This invention provides a highly dispersed magnesium hydroxide flame retardant masterbatch, comprising the following raw materials in parts by weight: 60-75 parts magnesium hydroxide, 15-25 parts carrier resin, 2-5 parts modifier, 3-8 parts compatibility toughening agent, 1-3 parts synergistic flame retardant, and 0.5-2 parts dispersing lubricant. The magnesium hydroxide includes nano-magnesium hydroxide and micron-sized magnesium hydroxide; The modifiers include silane coupling agents and titanate coupling agents.

[0022] The raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by this invention, by weight, include 60-75 parts of magnesium hydroxide, specifically 60 parts, 65 parts, 70 parts, or 75 parts. In this invention, the magnesium hydroxide includes nano-magnesium hydroxide and micron-sized magnesium hydroxide; the D50 of the nano-magnesium hydroxide is preferably 50-100 nm, and the purity is preferably ≥99%; the D50 of the micron-sized magnesium hydroxide is preferably 2-5 μm, the purity is preferably ≥98%, and the specific surface area is preferably 10-20 m². 2 / g; the mass ratio of the nano magnesium hydroxide to the micron magnesium hydroxide is preferably 1:3~5, and more preferably 1:4.

[0023] Based on the mass fraction of magnesium hydroxide, the raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by the present invention include 15-25 parts of carrier resin, specifically 15 parts, 18 parts, 20 parts, 22 parts, and 25 parts. In the present invention, the carrier resin preferably includes at least one of EVA resin and PP wax; the VA content (VA content represents the mass percentage of vinyl acetate (VAc) structural units in EVA resin, referring to the mass percentage content) of the EVA resin is preferably 18-28%, specifically 18%, 20%, 22%, 24%, 26%, and 28%; the melt index is preferably 5-15 g / 10 min (190℃ / 2.16 kg), specifically 5 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, and 15 g / 10 min.

[0024] Based on the mass fraction of magnesium hydroxide, the raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by this invention include 2-5 parts of a modifier, specifically 2 parts, 3 parts, 4 parts, or 5 parts. In this invention, the modifier includes a silane coupling agent and a titanate coupling agent. Preferably, the silane coupling agent includes at least one of KH-550 and KH-560; the titanate coupling agent preferably includes at least one of NDZ-101 and NDZ-201; the mass ratio of the silane coupling agent to the titanate coupling agent is preferably 1:2-3.

[0025] Based on the mass fraction of magnesium hydroxide, the raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by the present invention include 3 to 8 parts of a compatibility toughening agent, specifically 3, 4, 5, 6, 7, or 8 parts. In the present invention, the compatibility toughening agent preferably includes at least one of maleic anhydride-grafted POE and maleic anhydride-grafted EVA, and the grafting rate is preferably ≥0.8%.

[0026] Based on the mass fraction of magnesium hydroxide, the raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by this invention include 1 to 3 parts of a synergistic flame retardant, specifically 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, and 3 parts. In this invention, the synergistic flame retardant preferably includes at least one of zinc borate, zinc molybdate, and nano-silica.

[0027] Based on the mass fraction of magnesium hydroxide, the raw materials for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch provided by the present invention include 0.5 to 2 parts of a dispersing lubricant, specifically 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, and 2 parts. In the present invention, the dispersing lubricant preferably includes at least one of zinc stearate, polyethylene wax, and erucamide.

[0028] This invention also provides a method for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch described in the above technical solution, comprising the following steps: Magnesium hydroxide was modified by coating it with silane coupling agent and titanate coupling agent in sequence to obtain modified magnesium hydroxide. A carrier resin, a compatibility toughening agent, a synergistic flame retardant, and a dispersing lubricant are added to the modified magnesium hydroxide and premixed to obtain a premix; The premixed material is melt-kneaded to obtain the melt-kneaded material; The molten material is extruded and granulated to obtain the highly dispersed magnesium hydroxide flame retardant masterbatch.

[0029] In this invention, magnesium hydroxide is coated and modified sequentially using a silane coupling agent and a titanate coupling agent to obtain modified magnesium hydroxide.

[0030] In this invention, the coating modification preferably includes: After drying magnesium hydroxide, a silane coupling agent dilution is added to the magnesium hydroxide under stirring for a first coating, followed by a titanate coupling agent dilution for a second coating, to obtain modified magnesium hydroxide. In this invention, the drying temperature is preferably 105-115℃, and the drying time is preferably 4-6 hours; the mass concentration of the silane coupling agent dilution is preferably 10-15%, specifically 10%, 11%, 12%, 13%, 14%, or 15%; the solvent is preferably anhydrous ethanol; the mass concentration of the titanate coupling agent dilution is preferably 10-15%, specifically 10%, 11%, 12%, 13%, 14%, or 15%; the solvent is preferably anhydrous ethanol. In this invention, the stirring speed is preferably 1000-1400 rpm; the temperature of the first coating is preferably 80-90℃, and the time is preferably 20-30 minutes; the second coating is preferably at the same temperature as the first coating, and the time is preferably 15-20 minutes; after the second coating, it is also preferable to cool to below 50℃.

[0031] After obtaining the modified magnesium hydroxide, the present invention adds a carrier resin, a compatibility toughening agent, a synergistic flame retardant, and a dispersing lubricant to the modified magnesium hydroxide for premixing to obtain a premix. In the present invention, the premixing speed is preferably 800~1000 rpm, and the premixing time is preferably 15~25 min.

[0032] After obtaining the premixed material, the present invention performs melt kneading on the premixed material to obtain a melted material. In the present invention, the temperature of the melt kneading is preferably 120~150℃, specifically 120℃, 130℃, 140℃, or 150℃; the rotation speed is preferably 60~80 rpm, more preferably 70 rpm; and the time is preferably 8~12 min, specifically 8 min, 9 min, 10 min, 11 min, or 12 min.

[0033] After obtaining the internally mixed melt, the present invention extrudes and granulates the internally mixed melt to obtain the highly dispersed magnesium hydroxide flame retardant masterbatch. In the present invention, the extrusion granulation is preferably carried out using a twin-screw extruder; the twin-screw extruder preferably includes three temperature zones, the temperature of the first temperature zone is preferably 110~120℃, the temperature of the second temperature zone is preferably 130~140℃, the temperature of the third temperature zone is preferably 140~150℃, and the die head temperature is preferably 145~155℃; the screw speed is preferably 200~260rpm, specifically 200rpm, 210rpm, 220rpm, 230rpm, 240rpm, 250rpm, and 260rpm.

[0034] In this invention, the particle size of the highly dispersed magnesium hydroxide flame retardant masterbatch is preferably 2~4 nm.

[0035] The present invention also provides a halogen-free flame-retardant polyolefin composite material, comprising polyolefin and a flame retardant, wherein the flame retardant is the highly dispersed magnesium hydroxide flame-retardant masterbatch described in the above technical solution or the highly dispersed magnesium hydroxide flame-retardant masterbatch prepared by the preparation method described in the above technical solution.

[0036] In this invention, the polyolefin preferably includes at least one of PP, PE and EVA; the mass percentage of flame retardant in the halogen-free flame-retardant polyolefin composite material is preferably 15-30%, specifically 15%, 18%, 20%, 22%, 25%, 28%, or 30%.

[0037] The present invention does not impose any special limitations on the preparation method of the halogen-free flame-retardant polyolefin composite material; conventional injection molding, extrusion, or blown film processes can be used.

[0038] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 Raw material formulation (parts by weight): 15 parts nano magnesium hydroxide (D50 80nm, purity ≥99.5%), 55 parts micron magnesium hydroxide (D50 3μm, purity ≥98.5%, specific surface area 15m²). 2 / g), 20 parts of EVA resin (VA content 24%, melt index 10g / 10min (190℃ / 2.16kg)), 1 part of KH-560, 2 parts of NDZ-201, 5 parts of MAH-g-POE (grafting rate 1.0%), 1.5 parts of 2335 type zinc borate, and 0.5 parts of zinc stearate; (1) Mix nano magnesium hydroxide and micron magnesium hydroxide and vacuum dry at 110°C for 5 h; KH-560 and NDZ-201 are diluted with anhydrous ethanol to a mass concentration of 12% respectively; (2) Add the dried magnesium hydroxide to a high-speed mixer at a temperature of 85°C and a speed of 1200 rpm. First add KH-560 diluent and mix for 25 min, then add NDZ-201 diluent and mix for 20 min. Cool down to below 50°C to obtain modified magnesium hydroxide. (3) Add EVA resin, MAH-g-POE, 2335 type zinc borate and zinc stearate to modified magnesium hydroxide, mix at 900 rpm for 20 min to obtain a premix; (4) Add the premix to the internal mixer and mix at 135°C and 70 rpm for 10 min to obtain the internally mixed melt. (5) Add the molten material to a twin-screw extruder, with the temperature of each zone being 115℃-135℃-145℃-150℃ and the screw speed being 240rpm. Extrude, water cool, and pelletize to obtain flame retardant masterbatch with a particle size of 2~4mm. The actual image of the highly dispersed magnesium hydroxide flame retardant masterbatch obtained in this embodiment is shown below. Figure 1 The above; by Figure 1 As can be seen, the flame retardant masterbatch consists of uniform cylindrical particles with a concentrated particle size distribution ranging from 2 to 4 mm. The particle surface is smooth with no obvious agglomeration or clumping. The overall color is uniformly white, and the fluidity is good. This directly reflects the molding quality and dispersion uniformity of the flame retardant masterbatch under the micro-nano compound magnesium hydroxide and graded coating process of the present invention.

[0041] Example 2 Raw material formulation (parts by weight): 12 parts nano magnesium hydroxide (D50 70 nm, purity ≥99.3%), 60 parts micron magnesium hydroxide (D50 2.5 μm, purity ≥98.2%, specific surface area 12 m²). 2 / g), 18 parts PP wax, 0.8 parts KH-550, 1.6 parts NDZ-101, 6 parts MAH-g-EVA (grafting rate 1.0%), 1 part nano silica, 0.6 parts polyethylene wax; The preparation process was the same as in Example 1, except that the mixing temperature was adjusted to 140°C and the temperature of each zone of the twin-screw extruder was adjusted to 120°C-138°C-148°C-155°C.

[0042] Example 3 Raw material formulation (parts by weight): 10 parts nano magnesium hydroxide (D50 60nm, purity ≥99.2%), 58 parts micron magnesium hydroxide (D50 4μm, purity ≥98.3%, specific surface area 18m²). 2 / g), 22 parts of EVA resin + polyethylene wax (mass ratio 1:1, of which EVA resin VA content 24%, melt index 8g / 10min (190℃ / 2.16kg)), 1.2 parts of KH-560 + KH-550 (mass ratio 1:1), 2.4 parts of NDZ-201, 5 parts of MAH-g-POE + MAH-g-EVA (grafting rate 1.1% for both, mass ratio 1:1), 1 part of zinc molybdate, and 0.5 parts of erucamide; The preparation process was the same as in Example 1, except that the mixing temperature was adjusted to 130°C and the temperature of each zone of the twin-screw extruder was adjusted to 115°C-135°C-145°C-150°C.

[0043] Comparative Example 1 Referring to Example 1, the modifier was replaced with a single KH-560 3%.

[0044] Comparative Example 2 Referring to Example 1, MAH-g-POE was removed, while the remaining raw materials and preparation process were the same as in Example 1.

[0045] Comparative Example 3 Raw material formulation (parts by weight): 70 parts of micron-sized magnesium hydroxide (D50 is 3μm, purity ≥98.5%, specific surface area is 15m²). 2 20 parts of EVA resin (VA content 24%, melt index 10g / 10min (190℃ / 2.16kg)), 1 part of KH-560, 2 parts of NDZ-201, 5 parts of MAH-g-POE (grafting rate 1.0%), 1.5 parts of 2335 type zinc borate, and 0.5 parts of zinc stearate. Only micron-sized magnesium hydroxide is used, without further formulation. The preparation process is exactly the same as in Example 1.

[0046] Comparative Example 4 Raw material formulation (parts by weight): 70 parts nano-magnesium hydroxide (D50 80nm, purity ≥99.5%), 20 parts EVA resin (VA content 24%, melt index 10g / 10min (190℃ / 2.16kg)), 1 part KH-560, 2 parts NDZ-201, 5 parts MAH-g-POE (grafting rate 1.0%), 1.5 parts type 2335 zinc borate, and 0.5 parts zinc stearate. This formulation contains only nano-magnesium hydroxide and is not compounded. The preparation process is exactly the same as in Example 1.

[0047] Performance testing The flame-retardant masterbatches from Examples 1-3 and Comparative Examples 1-4 were added to PE, PP, and EVA resins at a mass fraction of 25%, respectively. Standard samples were injection molded, and the limiting oxygen index, flame retardant rating, impact strength, and tensile strength were tested according to national standards. Specifically: the limiting oxygen index was tested according to GB / T 2406.2-2009; the vertical burning flame retardant rating was determined according to GB / T 2408-2021 for UL94 rating; the notched impact strength of a simply supported beam was tested according to GB / T 1043.1-2008; and the tensile strength was tested according to GB / T1040.2-2018. The test results are shown in Table 1: Table 1 Performance test results of the masterbatches obtained in the examples and comparative examples

[0048] Test Conclusions: The flame-retardant masterbatch prepared in the embodiments of this invention, with a low filler content of 25%, enables the polyolefin composite material to meet the UL94 V-0 flame-retardant standard, with an oxygen index ≥29.8%, and maintains a high degree of mechanical property retention compared to the blank material. In contrast, Comparative Example 1, due to poor dispersibility caused by modification with a single coupling agent, experienced a significant decrease in both flame retardancy and mechanical properties. Comparative Example 2, lacking a compatible toughening agent, suffered a severe reduction in material toughness. This fully demonstrates that the graded coating of the composite modifier and the synergistic design of the compatible toughening agent and synergistic flame retardant in this invention can effectively achieve a balance between flame retardancy and mechanical properties.

[0049] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A highly dispersed magnesium hydroxide flame retardant masterbatch, characterized in that, The preparation raw materials include the following parts by weight: 60-75 parts magnesium hydroxide, 15-25 parts carrier resin, 2-5 parts modifier, 3-8 parts compatibility toughening agent, 1-3 parts synergistic flame retardant, and 0.5-2 parts dispersing lubricant; The magnesium hydroxide includes nano-magnesium hydroxide and micron-sized magnesium hydroxide; The modifiers include silane coupling agents and titanate coupling agents.

2. The highly dispersed magnesium hydroxide flame retardant masterbatch according to claim 1, characterized in that, The nano-magnesium hydroxide has a D50 of 50~100nm and a purity of ≥99%; The micron-sized magnesium hydroxide has a D50 of 2~5μm, a purity ≥98%, and a specific surface area of ​​10~20m². 2 / g.

3. The highly dispersed magnesium hydroxide flame retardant masterbatch according to claim 1 or 2, characterized in that, The mass ratio of the nano-magnesium hydroxide to the micron-magnesium hydroxide is 1:3~5.

4. The highly dispersed magnesium hydroxide flame retardant masterbatch according to claim 1, characterized in that, The silane coupling agent includes at least one of KH-550 and KH-560; The titanate coupling agent includes at least one of NDZ-101 and NDZ-201; The mass ratio of the silane coupling agent to the titanate coupling agent is 1:2~3.

5. The highly dispersed magnesium hydroxide flame retardant masterbatch according to claim 1, characterized in that, The carrier resin includes at least one of EVA resin and PP wax; the EVA resin has a VA content of 18-28% and a melt index of 5-15 g / 10 min; The compatibility toughening agent includes at least one of maleic anhydride-grafted POE and maleic anhydride-grafted EVA, with a grafting rate ≥0.8%; The synergistic flame retardant includes at least one of zinc borate, zinc molybdate, and nano-silica. The dispersing lubricant includes at least one of zinc stearate, polyethylene wax, and erucamide.

6. The method for preparing the highly dispersed magnesium hydroxide flame retardant masterbatch according to any one of claims 1 to 5, characterized in that, Includes the following steps: Magnesium hydroxide was modified by coating it with silane coupling agent and titanate coupling agent in sequence to obtain modified magnesium hydroxide. A carrier resin, a compatibility toughening agent, a synergistic flame retardant, and a dispersing lubricant are added to the modified magnesium hydroxide and premixed to obtain a premix; The premixed material is melt-kneaded to obtain the melt-kneaded material; The molten material is extruded and granulated to obtain the highly dispersed magnesium hydroxide flame retardant masterbatch.

7. The preparation method according to claim 6, characterized in that, The premixing speed is 800~1000 rpm, and the time is 15~25 min; The melting and mixing temperature is 120~150℃, the rotation speed is 60~80rpm, and the time is 8~12min.

8. The preparation method according to claim 6, characterized in that, The extrusion granulation is carried out using a twin-screw extruder; The twin-screw extruder includes three temperature zones: the first temperature zone has a temperature of 110~120℃, the second temperature zone has a temperature of 130~140℃, the third temperature zone has a temperature of 140~150℃, and the die head temperature has a temperature of 145~155℃; the screw speed is 200~260rpm.

9. A halogen-free flame-retardant polyolefin composite material, characterized in that, It includes polyolefins and flame retardants, wherein the flame retardant is the highly dispersed magnesium hydroxide flame retardant masterbatch according to any one of claims 1 to 5 or the highly dispersed magnesium hydroxide flame retardant masterbatch prepared by the preparation method according to any one of claims 6 to 8.

10. The halogen-free flame-retardant polyolefin composite material according to claim 9, characterized in that, The polyolefin includes at least one of PP, PE and EVA; The flame retardant content of the halogen-free flame-retardant polyolefin composite material is 15-30% by mass.

Images