Melted biphase high-flame-retardant nylon composite material as well as preparation method and application thereof

Abstract

The invention provides a melt biphase high-flame-retardant nylon composite material as well as a preparation method and application thereof. The melt biphase high-flame-retardant nylon composite material is prepared from the following raw materials in parts by weight: 100 parts of a nylon matrix, 5-30 parts of a low-melting-point phosphorus flame retardant, 10-20 parts of an inorganic flame retardant, 0-10 parts of reinforcing filler, 1-3 parts of a compatilizer, 2-4 parts of a dispersing agent, 0.2-1 part of an antioxidant and 0.5-1.5 parts of a lubricant, the melting point of the low-melting-point phosphorus-based flame retardant is 30-220 DEG C, and the weight part of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weight parts of the inorganic flame retardant and the reinforcing filler. According to the flame-retardant nylon material and the preparation method thereof, through scientific material proportioning and an optimized blending process, a high-content flame retardant can be added, and the prepared flame-retardant nylon material is uniform in filler dispersion, good in 3D printing process performance, balanced in strength and toughness and excellent in flame retardance and has huge application potential in multiple fields such as airplane passenger cabins, automobiles, buildings and electronic circuits.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, and in particular relates to a molten biphase high flame retardant nylon composite material, its preparation method and application. Background Technology

[0002] 3D printing is a rapidly developing new manufacturing technology in recent years. Its moldless and free-form characteristics make it easy and quick to produce complex parts, reduce production costs, shorten production time, and improve the efficiency and flexibility of the manufacturing supply chain.

[0003] Fused deposition modeling (FDM) is a commonly used polymer 3D printing technology. This process involves heating and melting thermoplastic resin materials, then stacking them layer by layer through micro-nozzles to form the final product. The raw material can be granules or filaments. Nylon is currently the most widely used engineering plastic, offering excellent overall performance and making it a cost-effective printing material for FDM. However, nylon is flammable, has a high heat release rate, and is prone to molten dripping during combustion, accelerating the spread of fire. Therefore, flame-retardant modification is required in various fields such as aircraft cabins, automobiles, and construction. Flame-retardant nylon used in traditional molding methods such as injection molding is very mature. However, flame-retardant nylon materials used in FDM 3D printing still face challenges such as difficulty in increasing the amount of flame retardant added, deterioration of 3D printing process performance, and loss of mechanical properties. There is an urgent need to develop flame-retardant nylon materials with superior overall performance in terms of flame retardancy, mechanical properties, and printing process performance. Summary of the Invention

[0004] The purpose of this invention is to provide a molten dual-phase high flame retardant nylon composite material, its preparation method and application. The molten dual-phase high flame retardant nylon composite material of this invention has good mechanical properties, excellent flame retardant properties, and high printing process performance.

[0005] This invention provides a melt-blown dual-phase nylon composite material with high flame retardant properties, comprising the following raw materials in parts by weight:

[0006] 100 parts nylon matrix, 5-30 parts low-melting-point phosphorus-based flame retardant, 10-20 parts inorganic flame retardant, 0-10 parts reinforcing filler, 1-3 parts compatibilizer, 2-4 parts dispersant, 0.2-1 parts antioxidant, and 0.5-1.5 parts lubricant;

[0007] The low-melting-point phosphorus-based flame retardant has a melting point of 30–220°C, and the weight percentage of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weight percentages of the inorganic flame retardant and the reinforcing filler.

[0008] Preferably, the low-melting-point phosphorus-based flame retardant includes one or more of 2-carboxyethylphenyl hypophosphite, cyclooctylhydroxypropylphosphine oxide, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxophosphaxanecyclo-6-one)-methyl]-succinic acid (DDP), tris(3-hydroxypropyl)phosphine oxide, and tri(xylene) phosphate.

[0009] Preferably, the inorganic flame retardant includes one or more of aluminum hydroxide, magnesium hydroxide, montmorillonite, zinc borate, and expanded graphite.

[0010] Preferably, the reinforcing filler includes one or more of glass fiber, silicon dioxide, titanium dioxide, mica, and calcium carbonate.

[0011] Preferably, the compatibilizer is polyethylene grafted with maleic anhydride and / or ethylene-octene copolymer grafted with maleic anhydride.

[0012] Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 1068, antioxidant 168, antioxidant 549, and antioxidant 542;

[0013] The lubricant is one or more of molybdenum disulfide, polyethylene wax, calcium stearate, sodium stearate, zinc stearate, and ethylene bis-stearamide;

[0014] The dispersant is a phosphate ester-polyester-polyether block copolymer and / or a hyperbranched polyphosphate ester.

[0015] This invention provides a method for preparing the molten dual-phase high flame-retardant nylon composite material as described above, comprising the following steps:

[0016] A) Mix the nylon matrix with inorganic flame retardants, reinforcing fillers, compatibilizers, antioxidants and lubricants to obtain a solid premixed raw material;

[0017] The low-melting-point phosphorus-based flame retardant is heated and melted, then mixed with a dispersant to obtain a liquid premixed raw material;

[0018] B) After melting and mixing the solid premixed raw materials, add the liquid premixed raw materials, blend and then extrude and granulate to obtain a molten dual-phase nylon composite material with high flame retardant properties.

[0019] Preferably, step B) is followed by:

[0020] C) The molten dual-phase high flame-retardant nylon composite material is melt-extruded to obtain molten dual-phase high flame-retardant nylon composite filament.

[0021] Preferably, in step B), after the liquid premixed raw material and the molten solid premixed raw material are blended, they are sheared and kneaded, and then extruded and granulated to obtain a molten dual-phase high flame-retardant nylon composite material.

[0022] This invention provides the application of the fused biphase high flame retardant nylon composite material as described above in fused deposition modeling 3D printing.

[0023] This invention provides a molten dual-phase nylon composite material with high flame retardant properties, comprising the following raw materials in parts by weight: 100 parts nylon matrix, 5-30 parts low-melting-point phosphorus-based flame retardant, 10-20 parts inorganic flame retardant, 0-10 parts reinforcing filler, 1-3 parts compatibilizer, 2-4 parts dispersant, 0.2-1 parts antioxidant, and 0.5-1.5 parts lubricant; the low-melting-point phosphorus-based flame retardant has a melting point of 30-220℃, and the weight of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weights of the inorganic flame retardant and the reinforcing filler. This invention innovatively designs a compound flame retardant system with a solid-liquid dual-phase structure at the molten deposition modeling (FDM) process temperature, solving the problems in existing technologies where the performance of the FDM process deteriorates significantly after the addition of flame retardants, resulting in nozzle clogging, uneven material output, and poor surface quality of the manufactured parts. By scientifically proportioning materials and optimizing the blending process, a higher content of flame retardant can be added. The resulting flame-retardant nylon material has uniformly dispersed filler, good 3D printing performance, balanced strength and toughness, and excellent flame retardant properties, making it a promising candidate for applications in various fields such as aircraft cabins, automobiles, construction, and electronic circuits. Detailed Implementation

[0024] This invention provides a melt-blown dual-phase nylon composite material with high flame retardant properties, comprising the following raw materials in parts by weight:

[0025] 100 parts nylon matrix, 5-30 parts low-melting-point phosphorus-based flame retardant, 10-20 parts inorganic flame retardant, 0-10 parts reinforcing filler, 1-3 parts compatibilizer, 2-4 parts dispersant, 0.2-1 parts antioxidant, and 0.5-1.5 parts lubricant;

[0026] The low-melting-point phosphorus-based flame retardant has a melting point of 30–220°C, and the weight percentage of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weight percentages of the inorganic flame retardant and the reinforcing filler.

[0027] In this invention, the nylon matrix is ​​preferably one or more of nylon 6, nylon 66, nylon 11, nylon 12, nylon 1010, and nylon 1012. The nylon matrix is ​​preferably a nylon material with a melt flow index of 2–100 g / 10 min (test load 2.16 kg), a molding shrinkage rate of no more than 0.5%, and a water absorption rate of no more than 1%. If the polymer melt flowability is too poor, the continuity of extrusion from the nozzle will be poor, requiring a higher extrusion pressure and easily causing nozzle clogging. If the melt flowability is too high, it is prone to leakage, stringing, and nozzle clogging, affecting the 3D printing quality. Therefore, the melt flow index of the nylon material should be within a suitable range. Furthermore, the molding shrinkage rate of the polymer used for 3D printing should not be too high, otherwise warping may easily occur, affecting the quality of the part. Water absorption during the printing process has a significant impact on the appearance quality and mechanical properties of the 3D printed part; therefore, the water absorption rate of the nylon matrix should not be too high.

[0028] In this invention, the melting point of the low-melting-point phosphorus-based flame retardant is preferably 30–220°C. The low-melting-point phosphorus-based flame retardant includes one or more of 2-carboxyethylphenyl hypophosphite, cyclooctylhydroxypropylphosphine oxide, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxophosphaxanecyclo-6-one)-methyl]-succinic acid (DDP), tris(3-hydroxypropyl)phosphine oxide, and tris(xylene) phosphate. The weight percentage of the low-melting-point phosphorus-based flame retardant is preferably 5–30 parts, more preferably 10–25 parts, such as 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0029] The low-melting-point phosphorus-based flame retardant melts into a liquid during fused deposition modeling (FDM) 3D printing, significantly increasing melt flowability. Appropriate addition of this agent has a positive effect on the mechanical properties of 3D printed parts, especially the interlayer bonding performance. However, when a large amount of low-melting-point phosphorus-based flame retardant is added, excessive melt flow can easily lead to leakage and stringing, as well as premature softening of the material in the feed tube. A large amount of melt cannot be extruded in time and will flow back into the feed tube, causing blockage after cooling. This invention increases melt strength and viscosity by using solid inorganic flame retardants and reinforcing fillers, thus avoiding the above phenomena. Therefore, the amount of low-melting-point phosphorus-based flame retardant added should not exceed the sum of the amounts of inorganic flame retardant and reinforcing filler added.

[0030] In this invention, the low-melting-point phosphorus-based flame retardant forms a liquid-solid two-phase system with the inorganic flame retardant, increasing the amount of flame retardant added and simultaneously improving the printing process performance, flame retardant performance, and mechanical properties of the nylon material used for 3D printing. Furthermore, the 3D-printed flame-retardant nylon parts with the added low-melting-point phosphorus-based flame retardant can remove more heat during the initial stage of combustion as the phosphorus-based flame retardant melts and absorbs heat, preventing excessive heat release rate and instantaneous temperature rise, thus increasing the fire suppression window.

[0031] In this invention, the inorganic flame retardant preferably includes one or more of aluminum hydroxide, magnesium hydroxide, montmorillonite, zinc borate, and expanded graphite. The weight percentage of the inorganic flame retardant is preferably 10 to 20 parts, more preferably 12 to 18 parts, such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts. It is preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0032] In this invention, the selected inorganic flame retardant and phosphorus-based flame retardant have a synergistic flame retardant effect. Magnesium hydroxide and aluminum hydroxide can decompose and release water of crystallization at relatively low temperatures, absorbing heat and lowering the temperature. The oxides formed after decomposition can act as an inorganic framework, combining with the carbon layer generated by the phosphorus-based flame retardant to form a more stable, dense, and high-temperature resistant composite carbon layer, effectively isolating oxygen and heat from entering the interior. Montmorillonite has a lamellar structure and can also combine with the carbon layer generated by the phosphorus-based flame retardant to form a physical barrier. The metal ions in montmorillonite can act as catalysts to accelerate cross-linking and carbonization reactions. The pyrolysis products of zinc borate can undergo viscous flow fusion with the pyrolysis products of the phosphorus-based flame retardant to generate a glass glaze layer, which in-situ seals the microcracks and pores inside the formed carbon layer, improving flame retardant performance. Expanded graphite can expand rapidly at high temperatures, forming a highly efficient heat insulation barrier and can also act as a carbon layer framework. The oxides on the surface of expanded graphite can react with the acidic substances generated by the phosphorus-based flame retardant, enhancing the adhesion and density of the carbon layer.

[0033] In this invention, the reinforcing filler preferably includes one or more of glass fiber, silica, titanium dioxide, mica, and calcium carbonate; the weight percentage of the reinforcing filler is preferably 0 to 10 parts, more preferably 2 to 8 parts, such as 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts, preferably within the range of any of the above values ​​as the upper or lower limit. The reinforcing filler can effectively improve the mechanical properties of the matrix.

[0034] In this invention, the compatibilizer preferably comprises polyethylene grafted maleic anhydride (MAH-g-PE) and / or ethylene-octene copolymer grafted maleic anhydride (MAH-g-POE). The compatibilizer is preferably 1 to 3 parts by weight, more preferably 1.5 to 2.5 parts, such as 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts, preferably within the range of any of the above values ​​as the upper or lower limit. The compatibilizer can improve the compatibility of the flame retardant and reinforcing filler with the nylon matrix.

[0035] In this invention, the dispersant is preferably a phosphate ester-polyester-polyether block copolymer and / or a hyperbranched polyphosphate ester, and the weight of the dispersant is preferably 2 to 4 parts, more preferably 2.5 to 3.5 parts, such as 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0036] In this invention, the phosphate ester-polyester-polyether block copolymer must be solvent-free, liquid at room temperature, and have an initial thermal decomposition temperature of not less than 270°C; the hyperbranched polyphosphate ester has a weight-average molecular weight of 1500–3000, a branching degree of 0.5–0.9, is liquid at room temperature, and has an initial thermal decomposition temperature of not less than 300°C. All the above dispersants are in liquid form, contain phosphate ester groups, have good compatibility with phosphorus-based flame retardants, and can be uniformly dispersed in the melt of low-melting-point phosphorus-based flame retardants, providing an "anchoring" effect on the phosphorus-based flame retardant droplets. The polyether, polyester segments, or hyperbranched structures have steric hindrance effects, preventing the agglomeration of solid fillers and simultaneously emulsifying the low-melting-point phosphorus-based flame retardant droplets. Under the combined action of the above compatibilizers and dispersants, the low-melting-point phosphorus-based flame retardant, inorganic flame retardant, and reinforcing filler can be uniformly dispersed in the nylon matrix.

[0037] In this invention, the antioxidant is preferably one or more of antioxidant 1010, antioxidant 1068, antioxidant 168, antioxidant 549, and antioxidant 542; the weight fraction of the antioxidant is preferably 0.2 to 1 part, more preferably 0.3 to 0.8 parts, such as 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, preferably within the range of any of the above values ​​as the upper or lower limit.

[0038] In this invention, the lubricant is preferably one or more of molybdenum disulfide, polyethylene wax, calcium stearate, sodium stearate, zinc stearate, and ethylene bis-stearamide; the weight percentage of the lubricant is preferably 0.5 to 1.5 parts, more preferably 0.8 to 1.2 parts, such as 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, and preferably within the range of any of the above values ​​as the upper or lower limit.

[0039] This invention also provides a method for preparing the above-mentioned melt-blended dual-phase high flame-retardant nylon composite material, which uses melt blending to form granules from raw materials, including the following steps:

[0040] A) Mix the nylon matrix with inorganic flame retardants, reinforcing fillers, compatibilizers, antioxidants and lubricants to obtain a solid premixed raw material;

[0041] The low-melting-point phosphorus-based flame retardant is heated and melted, then mixed with a dispersant to obtain a liquid premixed raw material;

[0042] B) After melting and mixing the solid premixed raw materials, add the liquid premixed raw materials, blend and then extrude and granulate to obtain a molten dual-phase nylon composite material with high flame retardant properties.

[0043] In this invention, all raw materials must be dried to maintain a moisture content below 0.2% before melt blending. The types and amounts of the nylon matrix, low-melting-point phosphorus flame retardant, inorganic flame retardant, reinforcing filler, compatibilizer, dispersant, antioxidant, and lubricant are consistent with those described above, and will not be repeated here.

[0044] The present invention preferably involves first premixing a nylon matrix with an inorganic flame retardant, reinforcing filler, compatibilizer, antioxidant, and lubricant by mechanical stirring to obtain a solid premixed raw material;

[0045] The low-melting-point phosphorus-based flame retardant is heated and melted, and the dispersant is fully dispersed in the low-melting-point phosphorus-based flame retardant melt by mechanical stirring to obtain a liquid premixed raw material.

[0046] After obtaining the solid premixed raw material and the liquid premixed raw material, the present invention loads the solid premixed raw material into a feeding hopper equipped with a metering device and sends it into a twin-screw extruder granulator. The liquid premixed raw material is added into a metering liquid feeding tank equipped with a heating and mechanical stirring device. The liquid premixed raw material is added to the molten solid premixed material melt in the twin-screw extruder granulator by side feeding.

[0047] This invention adds the liquid premixed raw material after the solid premixed raw material has been initially dispersed in the nylon melt. This can prevent the liquid premixed raw material from directly contacting the solid powder and quickly agglomerating. With the help of compatibilizers and dispersants, the low-melting-point phosphorus-based flame retardant droplets can be evenly dispersed in the nylon melt.

[0048] In this invention, the twin-screw extruder preferably has four temperature zones. The temperature of zone one is preferably 160–240°C, more preferably 180–220°C, such as 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, and 240°C, preferably within a range where any of the above values ​​is the upper or lower limit. The temperature of zone two is preferably 180–280°C, more preferably 200–250°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, and 280°C, preferably... With any of the above values ​​as the upper or lower limit, the temperature of the third zone is preferably 200-280℃, more preferably 220-250℃, such as 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, and preferably with any of the above values ​​as the upper or lower limit. The temperature of the fourth zone is preferably 180-260℃, more preferably 200-240℃, such as 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, and preferably with any of the above values ​​as the upper or lower limit.

[0049] Downstream of the liquid premixed raw material feeding location, a high-shear kneading block is preferably provided to further improve the dispersion of the additive in the nylon matrix through shear kneading. The high-shear kneading block is a combination of kneading blocks with a staggered angle of 30° and kneading blocks with a staggered angle of 45°. The 30° kneading block can distribute and mix the material, while the 45° kneading block can enhance shearing.

[0050] In this invention, the raw material undergoes a series of processes in a twin-screw extrusion granulation: melting of solid premixed raw materials, blending with liquid premixed raw materials, shearing and kneading, and extrusion granulation. Through material formulation design and process coordination, uniformly dispersed filler-based fused biphase high flame-retardant nylon composite material granules for fused deposition modeling (FDM) 3D printing can be obtained. These granules can be directly applied to granular FDM 3D printing, or drawn into filaments and applied as filament FDM 3D printing. The specific steps are as follows:

[0051] The obtained molten biphase high flame-retardant nylon composite material granules are added to a single-screw melt extrusion filament mill. After extrusion, the filaments are water-cooled, dried, laser-diametered, traction rollers, and wire storage rollers, and then collected by a material receiving mechanism to obtain flame-retardant nylon filaments for melt deposition molding.

[0052] In this invention, the processing temperature of the single-screw melt extrusion filament mill is as follows: the temperature of the first zone is preferably 180–240°C, more preferably 200–220°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, preferably within a range where any of the above values ​​is the upper or lower limit; the temperature of the second zone is preferably 200–280°C, more preferably 220–250°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, preferably within a range where any of the above values ​​is the upper limit. The upper or lower limit range of the temperature is preferred for the three zones, which are 200-280℃, more preferably 220-250℃, such as 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃. The upper or lower limit range of the temperature is preferred for the four zones, which are 180-260℃, more preferably 200-240℃, such as 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 26 ... such as 180℃, 290℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃.

[0053] This invention also provides an application of the aforementioned fused biphase high flame-retardant nylon composite material in fused deposition modeling 3D printing.

[0054] This invention provides a molten dual-phase nylon composite material with high flame retardant properties, comprising the following raw materials in parts by weight: 100 parts nylon matrix, 5-30 parts low-melting-point phosphorus-based flame retardant, 10-20 parts inorganic flame retardant, 0-10 parts reinforcing filler, 1-3 parts compatibilizer, 2-4 parts dispersant, 0.2-1 parts antioxidant, and 0.5-1.5 parts lubricant; the low-melting-point phosphorus-based flame retardant has a melting point of 30-220℃, and the weight of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weights of the inorganic flame retardant and the reinforcing filler. This invention innovatively designs a compound flame retardant system with a solid-liquid dual-phase structure at the molten deposition modeling (FDM) process temperature, solving the problems in existing technologies where the performance of the FDM process deteriorates significantly after the addition of flame retardants, resulting in problems such as spray blockage, uneven material output, and poor surface quality of the manufactured parts. By scientifically proportioning materials and optimizing the blending process, a higher content of flame retardant can be added. The resulting flame-retardant nylon material has uniformly dispersed filler, good 3D printing performance, balanced strength and toughness, and excellent flame retardant properties, making it a promising candidate for applications in various fields such as aircraft cabins, automobiles, construction, and electronic circuits.

[0055] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a molten dual-phase high flame-retardant nylon composite material, its preparation method, and its applications, but this should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] 100 parts of nylon 6 material, 3 parts of montmorillonite, 7 parts of magnesium hydroxide, 5 parts of titanium dioxide, 1.2 parts of polyethylene grafted maleic anhydride, 0.7 parts of 1068 antioxidant and 0.8 parts of sodium stearate lubricant are dried to ensure that the moisture content of all materials is kept below 0.2%. Then, they are mechanically stirred and premixed to obtain solid premixed raw materials.

[0058] 15 parts of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide low-melting-point phosphorus flame retardant were heated to 140°C to melt, and then 2.5 parts of phosphate ester-polyester-polyether block copolymer dispersant were added while stirring to obtain liquid premixed raw material.

[0059] The processing temperatures for the twin-screw extruder granulator are set as follows: Zone 1: 240℃, Zone 2: 260℃, Zone 3: 280℃, Zone 4: 280℃, and Die head: 260℃. Solid premixed raw materials are added to the metering hopper in Zone 1, while liquid premixed raw materials are added to the metering liquid-side feed tank in Zone 2, which is equipped with heating and mechanical stirring devices. High-shear kneading blocks are added to Zones 3 and 4 of the screw. The solid-liquid premixes are melt-blended according to the feeding rate set according to the feeding ratio. After extrusion from the die head, the mixture is water-cooled, blow-dried, granulated, and dried to obtain high flame-retardant nylon 6 composite material granules.

[0060] Granular material was added to a single-screw melt extrusion filament mill. The processing temperature was set as follows: Zone 1 temperature 220℃, Zone 2 temperature 280℃, Zone 3 temperature 280℃, and die temperature 260℃. After extrusion, the material was cooled by water, dried by air, subjected to laser diameter measurement, traction roller, and wire storage roller, and then collected by a material receiving mechanism to obtain flame-retardant nylon 6 filament for melt deposition modeling. This filament was then applied to a melt deposition modeling printer to prepare printing mechanics and flame-retardant test pieces, and to test whether the printing head would clog after 24 hours of continuous printing.

[0061] Example 2

[0062] 100 parts of nylon 11 material, 12 parts of zinc borate, 8 parts of silica, 1.5 parts of polyethylene grafted maleic anhydride, 0.5 parts of 1010 antioxidant and 0.6 parts of polyethylene wax lubricant are dried to ensure that the moisture content of all materials is kept below 0.2%. Then, they are mechanically stirred and premixed to obtain solid premixed raw materials.

[0063] 18 parts of [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxophosphorus hexane-6-one)-methyl]-succinic acid low-melting-point phosphorus flame retardant were heated to 200℃ to melt, and then 3 parts of phosphate ester-polyester-polyether block copolymer dispersant were added while stirring to obtain liquid premixed raw material.

[0064] The processing temperatures for the twin-screw extruder granulator are set as follows: Zone 1: 160℃, Zone 2: 200℃, Zone 3: 220℃, Zone 4: 220℃, and Die head: 200℃. Solid premixed raw materials are added to the metering hopper in Zone 1, while liquid premixed raw materials are added to the metering liquid-side feed tank in Zone 2, which is equipped with heating and mechanical stirring devices. High-shear kneading blocks are added to Zones 3 and 4 of the screw. The solid-liquid premixed materials are melt-blended according to the feeding rate set according to the feeding ratio. After extrusion from the die head, the mixture is water-cooled, blow-dried, granulated, and dried to obtain high flame-retardant nylon 11 composite material granules.

[0065] The granular material was directly applied to a granular fused deposition modeling (FDM) printer to prepare mechanical and flame-retardant test specimens, and the printing head was tested for clogging after 24 hours of continuous printing.

[0066] Comparative Example 1

[0067] 100 parts of nylon 11 material, 12 parts of zinc borate, 8 parts of silica, 1.5 parts of polyethylene grafted maleic anhydride, 0.5 parts of 1010 antioxidant and 0.6 parts of polyethylene wax lubricant are dried to ensure that the moisture content of all materials is kept below 0.2%. Then, they are mechanically stirred and premixed to obtain solid premixed raw materials.

[0068] 25 parts of [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxophosphorus hexane-6-one)-methyl]-succinic acid low-melting-point phosphorus flame retardant were heated to 200℃ to melt, and then 4 parts of phosphate ester-polyester-polyether block copolymer dispersant were added while stirring to obtain liquid premixed raw material.

[0069] The processing temperatures for the twin-screw extruder granulator were set as follows: Zone 1: 160℃, Zone 2: 200℃, Zone 3: 220℃, Zone 4: 220℃, and Die head: 200℃. Solid premixed raw materials were added to the metering hopper in Zone 1, while liquid premixed raw materials were added to the metering liquid-side feed tank in Zone 2, which is equipped with heating and mechanical stirring. High-shear kneading blocks were added to Zones 3 and 4 of the screw. The solid-liquid premixed materials were melt-blended according to the feeding ratio. After extrusion from the die head, the mixture was water-cooled, blow-dried, granulated, and dried to obtain high flame-retardant nylon 11 composite material granules. These granules were directly applied to a granule melt deposition modeling (FDM) printer to test for clogging after 24 hours of continuous printing.

[0070] Example 3

[0071] 100 parts of nylon 12 material, 5 parts of expanded graphite, 5 parts of zinc borate, 10 parts of mica, 1.2 parts of ethylene-octene copolymer grafted maleic anhydride, 0.4 parts of 168 antioxidant, and 1.5 parts of molybdenum disulfide lubricant were dried to ensure that the moisture content of all materials was kept below 0.2%. Then, the mixture was mechanically stirred and premixed to obtain a solid premixed raw material.

[0072] Ten parts of cyclooctylhydroxypropylphosphine oxide and ten parts of trimethylol phosphate low-melting-point phosphorus flame retardant were heated to 70°C to melt, and then 3.5 parts of hyperbranched polyphosphate dispersant were added while stirring to obtain liquid premixed raw materials.

[0073] The processing temperatures for the twin-screw extruder granulator are set as follows: Zone 1: 180℃, Zone 2: 195℃, Zone 3: 210℃, Zone 4: 210℃, and Die head: 200℃. Solid premixed raw materials are added to the metering hopper in Zone 1, while liquid premixed raw materials are added to the metering liquid-side feed tank in Zone 2, which is equipped with heating and mechanical stirring devices. High-shear kneading blocks are added to Zones 3 and 4 of the screw. The solid-liquid premixes are melt-blended according to the feeding rate set according to the feeding ratio. After extrusion from the die head, the mixture is water-cooled, blow-dried, granulated, and dried to obtain high flame-retardant nylon 12 composite material granules.

[0074] Granular material is added to a single-screw melt extrusion filament mill. The processing temperature is set as follows: Zone 1: 180℃, Zone 2: 200℃, Zone 3: 200℃, and Die temperature: 190℃. After extrusion, the material is cooled by water, dried by air, subjected to laser diameter measurement, traction roller, and wire storage roller, and then collected by a material receiving mechanism to obtain flame-retardant nylon 12 filament for melt deposition modeling. This filament is then applied to a melt deposition modeling printer to prepare printing mechanics and flame-retardant test pieces, and to test whether the printing head will clog after 24 hours of continuous printing.

[0075] The test results are shown in Table 1.

[0076] Table 1. Mechanical and flame-retardant properties of flame-retardant nylon fused deposition modeled specimens in the examples.

[0077]

[0078] Table 2. Fused deposition modeling process performance of flame-retardant nylon in the examples and comparative examples.

[0079]

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A melt-blown dual-phase nylon composite material with high flame retardant properties, comprising the following raw materials in parts by weight: 100 parts nylon matrix, 5-30 parts low-melting-point phosphorus-based flame retardant, 10-20 parts inorganic flame retardant, 0-10 parts reinforcing filler, 1-3 parts compatibilizer, 2-4 parts dispersant, 0.2-1 parts antioxidant, and 0.5-1.5 parts lubricant; The low-melting-point phosphorus-based flame retardant has a melting point of 30–220°C, and the weight percentage of the low-melting-point phosphorus-based flame retardant is not greater than the sum of the weight percentages of the inorganic flame retardant and the reinforcing filler.

2. The molten dual-phase high flame-retardant nylon composite material according to claim 1, characterized in that, The low-melting-point phosphorus-based flame retardant includes one or more of 2-carboxyethylphenyl hypophosphite, cyclooctylhydroxypropylphosphine oxide, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxophosphaxanecyclo-6-one)-methyl]-succinic acid (DDP), tris(3-hydroxypropyl)phosphine oxide, and tri(xylene) phosphate.

3. The molten dual-phase high flame-retardant nylon composite material according to claim 1, characterized in that, The inorganic flame retardant includes one or more of aluminum hydroxide, magnesium hydroxide, montmorillonite, zinc borate, and expanded graphite.

4. The molten dual-phase high flame-retardant nylon composite material according to claim 1, characterized in that, The reinforcing filler includes one or more of glass fiber, silicon dioxide, titanium dioxide, mica, and calcium carbonate.

5. The molten dual-phase high flame-retardant nylon composite material according to claim 1, characterized in that, The compatibilizer is polyethylene grafted with maleic anhydride and / or ethylene-octene copolymer grafted with maleic anhydride.

6. The molten dual-phase high flame-retardant nylon composite material according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 1010, antioxidant 1068, antioxidant 168, antioxidant 549, and antioxidant 542; The lubricant is one or more of molybdenum disulfide, polyethylene wax, calcium stearate, sodium stearate, zinc stearate, and ethylene bis-stearamide; The dispersant is a phosphate ester-polyester-polyether block copolymer and / or a hyperbranched polyphosphate ester.

7. A method for preparing the molten dual-phase high flame-retardant nylon composite material as described in claim 1, comprising the following steps: A) Mix the nylon matrix with inorganic flame retardants, reinforcing fillers, compatibilizers, antioxidants and lubricants to obtain a solid premixed raw material; The low-melting-point phosphorus-based flame retardant is heated and melted, then mixed with a dispersant to obtain a liquid premixed raw material; B) After melting and mixing the solid premixed raw materials, add the liquid premixed raw materials, blend and then extrude and granulate to obtain a molten dual-phase nylon composite material with high flame retardant properties.

8. The preparation method according to claim 7, characterized in that, Following step B) is also: C) The molten dual-phase high flame-retardant nylon composite material is melt-extruded to obtain molten dual-phase high flame-retardant nylon composite filament.

9. The preparation method according to claim 7, characterized in that, In step B), after the liquid premixed raw material and the molten solid premixed raw material are blended, they are sheared and kneaded, and then extruded and granulated to obtain a molten dual-phase nylon composite material with high flame retardant properties.

10. The application of the fused biphase high flame retardant nylon composite material as described in any one of claims 1 to 6 in fused deposition modeling 3D printing.

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