Halogen-free flame-retardant heat-conducting polyamide 66 additive system and application thereof

Abstract

The invention discloses a halogen-free flame-retardant heat-conducting polyamide 66 additive system and application thereof. Comprising the following raw material components in parts by weight: 25 to 55 parts of a phosphate flame retardant, 5 to 30 parts of linear phosphazene PMEP, 3 to 20 parts of melamine-formaldehyde resin coated linear chlorophosphazene polymer microcapsules, 3 to 15 parts of zinc hydroxystannate ZnSn (OH) 6, 2 to 10 parts of a rare earth charring agent RE-CA, 0.5 to 5 parts of a silane coupling agent and 0.2 to 2 parts of an antioxidant. The invention has the beneficial effects of realization of efficient flame retardation under a low addition amount, substantial improvement of heat-conducting property, maintenance of excellent mechanical properties and processability, reduction of smoke density, enhancement of fire safety, conformity to requirements of environmental regulations, simple preparation process and easy industrialization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame-retardant high polymer materials, and particularly relates to a halogen-free flame-retardant heat-conducting polyamide 66 additive system and application thereof. BACKGROUND

[0002] Polyamide 66 (PA66) is an engineering plastic with high strength, high heat resistance and easy processing, and is widely used in electronic appliances, new energy vehicles, 5G communication and LED heat dissipation shell fields. However, the limiting oxygen index (LOI) of PA66 is only about 24%, and serious dripping phenomenon occurs during combustion, which cannot meet the safety specification requirements, and the flame retardant performance must be improved by flame retardant modification. Although the traditional halogen-based flame retardant has high flame retardant efficiency, it has a large amount of smoke during combustion and produces harmful substances such as dioxin, which has been strictly limited or prohibited by international regulations such as RoHS and REACH. Therefore, halogen-free flame retardant technology has become the mainstream research direction.

[0003] The existing halogen-free flame-retardant PA66 system mainly uses phosphorus-based, nitrogen-based or inorganic filler components, but generally has the following defects: first, in order to achieve UL94 V-0 level flame retardant performance, the addition amount is usually ≥25wt%, which will cause the mechanical properties of the material to decrease significantly, such as the tensile strength and impact toughness decreasing by more than 20%, affecting the actual application; second, the thermal conductivity coefficient is low (usually <0.3 W / m·K), which is difficult to meet the high requirements of power devices on heat dissipation, especially in high-density electronic components, which is easy to cause heat accumulation and failure; third, the carbon layer formed during combustion is often loose and porous, with poor smoke suppression effect, insufficient fire safety redundancy, and the smoke density Ds-4 value often exceeds 300, increasing the risk of secondary harm; fourth, the compatibility of phosphazene or phosphate ester flame-retardant components with the PA66 matrix is poor, which is easy to precipitate and produce smoke phenomenon during processing, affecting the stability and processing efficiency of the material.

[0004] In recent years, the concept of "flame-retardant-thermal-conductive integration" has been proposed in order to simultaneously improve the flame-retardant and thermal-conductive properties of materials. The existing technology often uses simple blending to introduce Al2O3, BN and other thermal-conductive fillers, but this often leads to a sharp increase in melt viscosity and a significant decrease in impact toughness (such as a decrease to <5 kJ / m²), and the total addition amount still needs to be relatively high (>30 wt%) to barely achieve basic performance. At the same time, the introduction of thermal-conductive fillers may interfere with the synergistic effect of the flame-retardant system, resulting in a degradation of the flame-retardant grade to V-1 or V-2, which cannot balance high-efficiency flame-retardant and thermal-conductive properties. How to simultaneously achieve UL94 V-0 flame-retardant, thermal-conductive coefficient ≥0.8 W / m·K, and maintain the mechanical properties of injection-molding grade (such as tensile strength ≥70 MPa, notched impact strength ≥7kJ / m²) at a low total addition amount (≤20 wt%) has become a common technical problem faced by the industry. These defects limit the popularization and application of PA66 composite materials in high-safety and high-heat-dissipation demand occasions, and new types of multi-element synergistic additive systems need to be developed to solve them. SUMMARY

[0005] The present application aims to overcome the defects of the prior art and provide a halogen-free flame-retardant thermal-conductive polyamide 66 additive system.

[0006] Another object of the present application is to provide the use of the above-mentioned halogen-free flame-retardant thermal-conductive polyamide 66 additive system.

[0007] The technical solution of the present application is as follows:

[0008] A halogen-free flame-retardant thermal-conductive polyamide 66 additive system comprises the following raw material components by weight: phosphonate flame retardant 25-55 parts, linear phosphazene PMEP 5-30 parts, melamine-formaldehyde resin-coated linear chlorophosphazene polymer microcapsules 3-20 parts, zinc hydroxystannate ZnSn(OH)6 3-15 parts, rare earth charring agent RE-CA 2-10 parts, silane coupling agent 0.5-5 parts, and antioxidant 0.2-2 parts.

[0009] The particle size D50 of the above-mentioned melamine-formaldehyde resin-coated linear chlorophosphazene polymer microcapsules is 1-5 μm.

[0010] The rare earth elements in the above-mentioned rare earth charring agent RE-CA are Ce and La, and the total amount of rare earth is 15-25 wt%.

[0011] In a preferred embodiment of the present application, the phosphonate flame retardant is resorcinol bis(diphenyl phosphate) and / or bisphenol A bis(diphenyl phosphate).

[0012] In a preferred embodiment of the present application, the preparation method of the melamine-formaldehyde resin-coated linear chlorophosphazene polymer microcapsules comprises:

[0013] (1) linear chlorophosphonate polymer PDCP is dissolved in tetrahydrofuran (THF) to prepare 5-15 wt% oil phase;

[0014] (2) water phase is prepared, which contains MF prepolymer prepared by pre-condensation of melamine and formaldehyde at a molar ratio of 1:2-3 at pH 8.0-9.0 and 70-80℃ for 30-60 min;

[0015] (3) the oil phase obtained in step (1) is injected into the water phase obtained in step (2), and shearing emulsification is carried out at 20-30℃ (6000-10000 rpm, 3-10 min);

[0016] (4) 0.3-1.0 wt% p-toluenesulfonic acid is added dropwise to the material obtained in step (3) to adjust the pH to 4.5-5.5, and then the temperature is raised to 55-65℃ for 1.5-3 h for curing;

[0017] (5) the material obtained in step (4) is sequentially filtered and vacuum dried to obtain the product.

[0018] In a preferred embodiment of the present application, the preparation method of the rare earth carbonization agent RE-CA comprises:

[0019] (1) Ce(NO3)3·6H2O and La(NO3)3·6H2O are dissolved in deionized water at a molar ratio of 6-9:1-4 to prepare a solution with a concentration of 0.3-0.8 mol / L;

[0020] (2) at a temperature of 50-70℃, hydroxyethylidene diphosphonic acid (HEDP) in an amount equal to the total amount of Ce and La is added dropwise to the solution obtained in step (1) while maintaining the pH at 4.0-5.5, and the reaction is carried out for 1.5-3 h, followed by cooling, filtration, and drying at 100-120℃.

[0021] In a preferred embodiment of the present application, the silane coupling agent is KH-560, KH-550 or KH-570.

[0022] In a preferred embodiment of the present application, the antioxidant is 1010 and / or antioxidant 168.

[0023] The above-mentioned halogen-free flame-retardant and heat-conducting polyamide 66 additive system is used in the preparation of a polyamide 66 composite material.

[0024] A polyamide 66 composite material comprising the above-mentioned halogen-free flame-retardant and heat-conducting polyamide 66 additive system.

[0025] In a preferred embodiment of the present application, boron nitride is also present.

[0026] Further preferably, the particle size of the boron nitride is 4-6 μm.

[0027] The beneficial effects of the present application are:

[0028] 1. The present application can achieve UL94 V-0 level flame retardation (1.6 mm thickness, t1+t2≤9.1 s, no dripping) and LOI≥32% with a total additive amount≤20wt%, which is much better than the 25-30wt% additive level of traditional halogen-free systems, reducing material cost and improving processing efficiency.

[0029] 2. The present application can increase the thermal conductivity to≥0.8 W / m·K (up to 1.05 W / m·K), which is about 3 times higher than that of pure PA66, meeting the self-cooling needs of LED heat dissipation shells, connectors and other occasions, and avoiding faults caused by heat accumulation.

[0030] 3. The present application can keep the mechanical property retention rate≥85%, the tensile strength≥70 MPa, the notched impact strength≥7kJ / m 2 , and the melt flow rate 15-21 g / 10 min, ensuring that the material is suitable for injection molding of thin-walled complex parts.

[0031] 4. The present application can reduce the smoke density Ds-4 by≥30% (as low as 228), compact the carbon layer (thickness up to 1.9mm), improve fire safety, and reduce secondary hazards;

[0032] 5. All components of the present application are halogen-free and red phosphorus-free, in line with RoHS, REACH and WEEE environmental regulations, avoiding the release of harmful substances;

[0033] 6. The preparation process of the present application is simple, which can be realized by using existing double screw extruders, easy to industrialize production, low cost, and good application prospect. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described and explained below through specific embodiments.

[0035] In the following examples and comparative examples:

[0036] The relative viscosity ηrel of PA66 is 2.70±0.02, the water content is 420 ppm, and the DSM J-2300;

[0037] The RDP is an industrial grade;

[0038] The PMEP is an industrial grade;

[0039] The particle size D50 of the PDCP@MF microcapsule is 3.2 μm, and the coating rate is 83%;

[0040] ZnSn(OH)6 is an industrial grade;

[0041] The Ce:La molar ratio of RE-CA is 7:3, the total rare earth content is 22.4 wt%, and the 800°C carbon residue rate is 40.1%;

[0042] KH-560 is an industrial grade;

[0043] Antioxidant 1010 and antioxidant 168 are both industrial grades;

[0044] The preparation method of the above PDCP@MF microcapsules comprises:

[0045] (1) Dissolve linear chlorophosphonate polymer PDCP in tetrahydrofuran (THF) to prepare a 10 wt% oil phase;

[0046] (2) Prepare an aqueous phase containing an MF prepolymer, wherein the MF prepolymer is prepared by pre-condensation of melamine and formaldehyde at a molar ratio of 1:2 at pH 8.0 and 80°C for 30 min;

[0047] (3) Inject the oil phase obtained in step (1) into the aqueous phase obtained in step (2), and shear emulsify at 25°C (8000 rpm, 5 min);

[0048] (4) Add 0.5 wt% p-toluenesulfonic acid to the material obtained in step (3) to adjust the pH to 5, and then heat to 60°C for 2 h for solidification;

[0049] (5) Filter and vacuum dry the material obtained in step (4) in sequence to obtain a product with a particle size D50 of 3 μm, a coating rate of ≥80%, and a thermal decomposition peak that is increased by ≥35°C compared to that of the uncoated product;

[0050] The preparation method of the above RE-CA comprises:

[0051] (1) Dissolve Ce(NO3)3·6H2O and La(NO3)3·6H2O in deionized water at a molar ratio of 7:3 to prepare a solution with a concentration of 0.5 mol / L;

[0052] (2) At a temperature of 60°C, add hydroxyethylidene diphosphonic acid (HEDP) in an amount equal to the total amount of Ce and La to the solution obtained in step (1), maintain the pH at 4.0, and react for 2 h, then sequentially cool, filter, and dry at 110°C to obtain white powder RE-CA, with a total rare earth content of 20 wt% and an 800°C carbon residue rate of ≥38%

[0053] The performance testing methods of the products obtained in the following examples and comparative examples are as follows:

[0054] UL94 Vertical Burning: GB / T 2408-2021, 1.6 mm and 0.8 mm bar;

[0055] LOI: GB / T 2406.2-2020;

[0056] Thermal Conductivity: ISO 22007-2, Hot-Disk TPS 2500 S, 25 °C;

[0057] Mechanical: ISO 527-1 / -2 (tensile 50 mm / min), ISO 179-1eA (notched impact 23 °C);

[0058] Smoke Density: GB / T 8627-2007 (NBS box, radiant power 25 kW / m²);

[0059] Melt Index: ISO 1133-1, 275 °C / 2.16 kg.

[0060] Example 1 (Upper Limit Formulation)

[0061] The formulation of this example is as follows in parts by weight: PA66 80 parts, halogen-free flame-retardant thermally conductive polyamide 66 additive system 20 parts, wherein the specific formulation components of the halogen-free flame-retardant thermally conductive polyamide 66 additive system are as follows in parts by weight: RDP 55 parts, PMEP 30 parts, PDCP@MF microcapsule 20 parts, ZnSn(OH)6 15 parts, RE-CA 10 parts, KH-560 5 parts, antioxidant 1010 + antioxidant 168 (ratio 1:1) 2 parts;

[0062] The specific process steps of this example include:

[0063] (1) Premixing: all components except PA66 are put into a 100 L high-speed mixer, with a temperature setting of 70 °C and a rotation speed of 800 rpm, and premixed for 10 min to obtain premix A;

[0064] (2) Extrusion: a co-rotating twin-screw extruder (length-diameter ratio L / D = 40) is used, 100 parts of PA66 are added to the main feeding port, and premix A is added to the side feeding port, with a temperature distribution of 230 / 240 / 255 / 265 / 270 / 270 / 265 / 260 / 255 °C, a vacuum degree of ≤-0.09 MPa, and a screw rotation speed of 400 rpm; after extrusion, draw bar water cooling, air blowing drying and granulation are carried out;

[0065] (3) Post-treatment: the granules are air-dried at 120 °C for 4 h and sealed for use;

[0066] (4) Injection molding: using an electric injection molding machine, the temperature of the barrel is 270°C, the temperature of the mold is 90°C, one-time molding of 1.6 mm UL94 strips, 80x10x4 mm mechanical strips and Φ50 mmx3 mm heat-conducting round pieces.

[0067] The detection results of this example are as follows: UL94 (1.6 mm): V-0, t1+t2=3.2 s, no dripping; LOI: 34.5%; thermal conductivity: 0.91 W / m•K; tensile strength: 73 MPa; notched impact strength: 7.8 kJ / m²; smoke density: Ds-4 260; melt flow rate: 15 g / 10 min.

[0068] Example 2 (lower limit formula)

[0069] The formula of this example is as follows in parts by weight: PA66 80 parts, halogen-free flame-retardant heat-conducting polyamide 66 additive system 20 parts, wherein the specific formula components of the halogen-free flame-retardant heat-conducting polyamide 66 additive system are as follows in parts by weight: RDP 25 parts, PMEP 5 parts, PDCP@MF microcapsule 3 parts, ZnSn(OH)6 3 parts, RE-CA 2 parts, KH-550 0.5 parts, antioxidant 1010+antioxidant 168 (ratio 1:1) 0.2 parts.

[0070] The specific process steps of this example are the same as those of Example 1, except that the premixing temperature is reduced to 50°C and the screw speed is reduced to 250 rpm, and the remaining parameters remain unchanged.

[0071] The detection results of this example are as follows: UL94 (1.6 mm): V-0, t1+t2=9.1 s, no dripping; LOI: 32.1%; thermal conductivity: 0.80 W / m•K; tensile strength: 71 MPa; notched impact strength: 7.2 kJ / m²; smoke density: Ds-4 295; melt flow rate: 19 g / 10 min.

[0072] Example 3 (intermediate formula)

[0073] The formula of this example is as follows in parts by weight: PA66 82 parts, halogen-free flame-retardant heat-conducting polyamide 66 additive system 18 parts, wherein the specific formula components of the halogen-free flame-retardant heat-conducting polyamide 66 additive system are as follows in parts by weight: RDP 40 parts, PMEP 15 parts, PDCP@MF microcapsule 10 parts, ZnSn(OH)6 8 parts, RE-CA 5 parts, KH-570 2 parts, antioxidant 1010+antioxidant 168 (ratio 1:1) 1 part.

[0074] The specific process steps of this example are the same as those of Example 1.

[0075] The detection results of this example are as follows: UL94 (1.6 mm): V-0, t1+t2=5.5 s; LOI: 33.4%; thermal conductivity: 0.85 W / m•K; tensile strength: 75 MPa; notched impact strength: 8.1 kJ / m²; melt flow rate: 18 g / 10 min.

[0076] Example 4 (BDP completely replaces RDP)

[0077] The formulation of this example is as follows in parts by weight: PA66 82 parts, halogen-free flame-retardant heat-conducting polyamide 66 additive system 18 parts, wherein the specific formulation components of the halogen-free flame-retardant heat-conducting polyamide 66 additive system are as follows in parts by weight: BDP 40 parts (completely equal-mass replacement of RDP in Example 3) and the remaining components and amounts are completely consistent with Example 3.

[0078] The specific process steps of this example are the same as those of Example 1.

[0079] The detection results of this example are as follows: UL94 (1.6 mm): V-0, t1+t2=6.0 s; LOI: 32.8%; thermal conductivity: 0.84 W / m•K; tensile strength: 74 MPa; notched impact strength: 7.9 kJ / m².

[0080] Example 5 (PDCP@MF particle size D50=1.2 μm)

[0081] The formulation of this example is completely the same as that of Example 3.

[0082] In the specific process of this example, only the microcapsule preparation link is adjusted: shear emulsification speed 10000 rpm, time 3 min, particle size D50=1.2 μm, coating rate 87%; the remaining extrusion and injection molding parameters are completely consistent with those of Example 1.

[0083] The detection results of this example are as follows: UL94: V-0, t1+t2=5.3 s; thermal conductivity: 0.86 W / m•K; notched impact strength: 8.3 kJ / m²; smoke density Ds-4 252.

[0084] Example 6 (RE-CA Ce:La=9:1)

[0085] The formulation of this example is completely the same as that of Example 3, only the Ce:La molar ratio is 9:1 when RE-CA is synthesized, the total amount of rare earth is 24.2 wt%, and the carbon residue rate at 800°C is 41%.

[0086] The specific process steps of this example are the same as those of Example 1.

[0087] The detection results of this example are: UL94: V-0, t1+t2=5.1 s; LOI: 34.0%; thermal conductivity: 0.85 W / m•K.

[0088] Example 7 (ZnSn(OH)6 surface titanate modification)

[0089] The formulation of this example is exactly the same as that of Example 3, except that the ZnSn(OH)6 is additionally subjected to 1 wt% wet surface modification with titanate 201 and dried at 100°C for 2 h.

[0090] The specific process steps of this example are the same as those of Example 1.

[0091] The detection results of this example are: UL94: V-0, t1+t2=5.2 s; thermal conductivity: 0.85 W / m•K; notched impact strength: 8.4 kJ / m²; smoke density Ds-4 228 (decreased by 12% compared with Example 3).

[0092] Example 8 (extreme parameters of side feeding)

[0093] The formulation of this example is exactly the same as that of Example 3.

[0094] In the specific process of this example, only the twin screw parameters are adjusted: length-diameter ratio L / D=48, vacuum degree-0.095 MPa, screw speed 450 rpm, residence time 38 s, and the rest remain unchanged.

[0095] The detection results of this example are: UL94: V-0, t1+t2=5.0 s; melt flow rate: 21 g / 10 min; tensile strength: 74 MPa; notched impact strength: 8.0 kJ / m².

[0096] Example 9 (additional 3 parts of BN compounding)

[0097] The formulation of this example is based on Example 3, with the addition of 3 parts of BN (particle size D50=5 μm, Dandong Baiter), total addition amount 18 wt%, and the rest of the components unchanged.

[0098] The specific process steps of this example are the same as those of Example 1.

[0099] The detection results of this example are: UL94: V-0, t1+t2=5.4 s; thermal conductivity: 1.05 W / m•K; tensile strength: 73 MPa; notched impact strength: 7.5 kJ / m².

[0100] Example 10 (RE-CA upper limit 10 parts)

[0101] The formulation of the embodiment is 83 parts of PA66 and 17 parts of halogen-free flame-retardant heat-conducting polyamide 66 additive system, wherein the specific formulation components of the halogen-free flame-retardant heat-conducting polyamide 66 additive system are 35 parts of RDP, 10 parts of PMEP, 8 parts of PDCP@MF microcapsule, 6 parts of ZnSn(OH)6, 10 parts of RE-CA, 2 parts of KH-560, and 1 part of antioxidant 1010+antioxidant 168 (ratio 1:1) by weight

[0102] The specific process steps of the embodiment are the same as those of Example 1.

[0103] The detection results of the embodiment are as follows: UL94: V-0, t1+t2=4.9 s; LOI: 35.1%; carbon layer thickness 1.9 mm; thermal conductivity: 0.82 W / m•K; tensile strength: 70 MPa; notched impact strength: 7.0 kJ / m².

[0104] Example 11 (antioxidant 168 alone)

[0105] The formulation of the embodiment is the same as that of Example 3, except that the antioxidant is changed to 2 parts of 168 and 0 parts of 1010.

[0106] The specific process steps of the embodiment are the same as those of Example 1.

[0107] The detection results of the embodiment are as follows: yellowness index ΔYI=2.3 (<3) after three extrusions; UL94: V-0, t1+t2=5.6 s; and the rest of the properties differ by ≤3% from those of Example 3.

[0108] Comparative Example 1 (without PDCP@MF)

[0109] The formulation of the comparative example is 80 parts of PA66 and 20 parts of a comparative additive system, wherein the specific formulation components of the comparative additive system are 50 parts of RDP (to make up for 10 parts of PDCP@MF), 15 parts of PMEP, 8 parts of ZnSn(OH)6, 5 parts of RE-CA, 2 parts of KH-570, 1 part of antioxidant 1010+antioxidant 168 (ratio 1:1), and 0 parts of PDCP@MF by weight.

[0110] The specific process steps of the comparative example are the same as those of Example 1.

[0111] The detection results of the comparative example are as follows: UL94 (1.6 mm): V-2, with dripping ignition of degreasing cotton; LOI: 28.2%; thermal conductivity: 0.81 W / m•K; notched impact strength: 5.9 kJ / m²; smoke density Ds-4 345.

[0112] Comparative Example 2 (without RE-CA)

[0113] The formulation of the present comparative example is 82 parts of PA66 and 18 parts of a comparative additive system, wherein the specific formulation components of the comparative additive system are 40 parts of RDP, 20 parts of PMEP (5 parts of RE-CA are supplemented), 10 parts of PDCP@MF microcapsule, 8 parts of ZnSn(OH)6, 2 parts of KH-570, 1 part of antioxidant 1010+antioxidant 168 (ratio 1:1), and 0 parts of RE-CA.

[0114] The specific process steps of the present comparative example are the same as those of Example 1.

[0115] The test results of the present comparative example are as follows: UL94: V-0, t1+t2=10.2 s; the carbon layer is loose; smoke density Ds-4 365 (increased by 41% compared with Example 3); thermal conductivity: 0.79 W / m·K.

[0116] Comparative Example 3 (without ZnSn(OH)6)

[0117] The formulation of the present comparative example is 82 parts of PA66 and 18 parts of a comparative additive system, wherein the specific formulation components of the comparative additive system are 40 parts of RDP, 15 parts of PMEP, 10 parts of PDCP@MF microcapsule, 5 parts of RE-CA, 2 parts of KH-570, 1 part of antioxidant 1010+antioxidant 168 (ratio 1:1), and 0 parts of ZnSn(OH)6, and 8 parts of ordinary ZnSnO3 are used instead.

[0118] The specific process steps of the present comparative example are the same as those of Example 1.

[0119] The test results of the present comparative example are as follows: UL94: V-1, serious dripping; smoke density Ds-4 340; notched impact strength: 6.2 kJ / m²; thermal conductivity: 0.80 W / m·K.

[0120] Comparative Example 4 (traditional Al2O3+ADP simple blending)

[0121] The formulation of the present comparative example is 66 parts of PA66 and 34 parts of a comparative additive system, wherein the specific formulation components of the comparative additive system are 25 parts of spherical Al2O3 (particle size D50=15 μm), 8 parts of ADP (diethyl aluminum hypophosphite), 1 part of KH-550, 1 part of antioxidant 1010+antioxidant 168 (ratio 1:1), and the total amount of the additive is 34 wt%.

[0122] The specific process steps of the present comparative example are the same as those of Example 1, except that the extrusion temperature is lowered by 5°C to prevent Al2O3 from wearing the screw.

[0123] The test results of the present comparative example are as follows: UL94: V-2; LOI: 26.5%; thermal conductivity: 0.78 W / m•K; melt flow rate: 5 g / 10 min; notched impact strength: 4.1 kJ / m2; tensile strength: 58 MPa.

[0124] The comparison of the above examples and comparative examples is shown in the following Table 1:

[0125] No. Core formulation features (wt parts) Total additive amount UL94 (1.6 mm) LOI (%) Thermal conductivity (W / m-K) Tensile strength (MPa) Impact strength (kJ / m²) Smoke density Ds-4 Remarks Example 1 High addition: RDP 55 + PMEP 30 + PDCP@MF 20 + ZnSn(OH)6 15 + RE-CA 10 20% V-0 (3.2 s) 34.5 0.91 73 7.8 260 Upper limit formulation, best performance Example 2 Low addition: RDP 25 + PMEP 5 + PDCP@MF3 + ZnSn(OH)63 + RE-CA 2 20% V-0 (9.1 s) 32.1 0.80 71 7.2 295 Lower limit formulation, still meet the standard Example 3 Median formulation: RDP 40 + PMEP 15 + PDCP@MF 10 + ZnSn(OH)6 8 + RE-CA 5 18% V-0 (5.5 s) 33.4 0.85 75 8.1 — Balanced performance representative Example 4 BDP instead of RDP (40 parts) 18% V-0 (6.0 s) 32.8 0.84 74 7.9 — BDP completely replaceable Example 5 PDCP@MF particle size D50=1.2 μm 18% V-0 (5.3 s) — 0.86 — 8.3 252 Particle size refinement improves impact Example 6 RE-CA Ce:La=9:1 18% V-0 (5.1 s) 34.0 0.85 — — — High Ce ratio improves LOI Example 7 ZnSn(OH)6 modified with titanate 18% V-0 (5.2 s) — 0.85 — 8.4 228 Surface modification reduces smoke by 12% Example 8 High shear process (L / D=48, 450 rpm) 18% V-0 (5.0 s) — — 74 8.0 — Process optimization, MFR↑ Example 9 Additional BN 3 parts (total addition 18%) 18% V-0 (5.4 s) — 1.05 73 7.5 — Thermal conductivity breakthrough 1.0 W / m-K Example 10 RE-CA increased to 10 parts 17% V-0 (4.9 s) 35.1 0.82 70 7.0 — Carbon layer thickening, slightly brittle Example 11 Antioxidant 168 alone (2 parts) 18% V-0 (5.6 s) — — — — — Good thermal stability, ΔYI=2.3 Comparative Example 1 No PDCP@MF, RDP supplemented to 50 parts 20% V-2 (dropping) 28.2 0.81 — 5.9 345 Flame retardant failure, smoke↑ Comparative Example 2 No RE-CA, PMEP supplemented to 20 parts 18% V-0 (10.2 s) — 0.79 — — 365 Loose carbon layer, smoke↑ 41% Comparative Example 3 no ZnSn(OH)6, use ZnSnO3 instead 18% V-1 (dropping) — 0.80 — 6.2 340 Severe dropping, impact↓ Comparative Example 4 Traditional Al203+ ADP blend 34% V-2 26.5 0.78 58 4.1 — High addition, low performance, MFR extremely poor

[0126] The above description is merely preferred embodiments of the present application, and thus is not intended to limit the scope of the present application. It is therefore intended that equivalents of the disclosed embodiments also be encompassed within the scope of the present application, which is limited solely by the following claims and their equivalents.

Claims

1. A halogen-free flame retardant heat conductive polyamide 66 additive system characterized by: The raw material components include the following weight parts: phosphate ester flame retardant 25-55 parts, linear phosphazene PMEP 5-30 parts, melamine-formaldehyde resin coated linear chlorophosphazene polymer microcapsule 3-20 parts, zinc hydroxystannate ZnSn(OH)63-15 parts, rare earth carbonization agent RE-CA 2-10 parts, silane coupling agent 0.5-5 parts, and antioxidant 0.2-2 parts; The particle size D50 of the melamine-formaldehyde resin coated linear chlorophosphazene polymer microcapsule is 1-5 μm. The rare earth elements in the rare earth carbonization agent RE-CA are Ce and La, and the total amount of rare earth is 15-25 wt%.

2. A halogen-free flame retardant heat conductive polyamide 66 additive system as claimed in claim 1, characterized in that: The phosphate ester flame retardant is resorcinol bis(diphenyl phosphate) and / or bisphenol A bis(diphenyl phosphate).

3. The halogen-free flame-retardant and thermally conductive polyamide 66 additive system as described in claim 1, characterized in that: The preparation method of the melamine-formaldehyde resin coated linear chlorophosphazene polymer microcapsule includes: (1) Dissolve linear chlorophosphazene polymer PDCP in tetrahydrofuran (THF) to prepare an oil phase with a concentration of 5-15 wt%; (2) Prepare an aqueous phase containing MF prepolymer, which is prepared by pre-condensation of melamine and formaldehyde at a molar ratio of 1:2-3 at pH 8.0-9.0 and 70-80°C for 30-60 min; (3) Inject the oil phase obtained in step (1) into the aqueous phase obtained in step (2), and shear emulsify at 20-30°C (6000-10000 rpm, 3-10 min); (4) Add 0.3-1.0 wt% of p-toluenesulfonic acid to the material obtained in step (3) to adjust the pH to 4.5-5.5, and then heat to 55-65°C for 1.5-3 h; (5) Filter and vacuum dry the material obtained in step (4) in sequence to obtain the product.

4. A halogen-free flame retardant heat conductive polyamide 66 additive system as claimed in claim 1, wherein: The preparation method of the rare earth carbonization agent RE-CA includes: (1) Dissolve Ce(NO3)3·6H2O and La(NO3)3·6H2O in deionized water at a molar ratio of 6-9:1-4 to prepare a solution with a concentration of 0.3-0.8 mol / L; (2) At a temperature of 50-70°C, add hydroxyethylidene diphosphonic acid (HEDP) in an amount equal to the total amount of Ce and La to the solution obtained in step (1) while maintaining the pH at 4.0-5.5, and react for 1.5-3 h, and then sequentially cool, filter, and dry at 100-120°C to obtain the product.

5. The halogen-free flame-retardant and thermally conductive polyamide 66 additive system as described in claim 1, characterized in that: The silane coupling agent is KH-560, KH-550, or KH-570.

6. A halogen-free flame retardant, heat conductive polyamide 66 additive system as specified in claim 1 characterized by: The antioxidant is 1010 and / or antioxidant 168.

7. Use of the halogen-free flame-retardant heat-conductive polyamide 66 additive system according to any one of claims 1 to 6 for the preparation of a polyamide 66 composite material.

8. A polyamide 66 composite characterized by: It has the halogen-free flame-retardant heat-conductive polyamide 66 additive system according to any one of claims 1 to 6.

9. A polyamide 66 composite material as claimed in claim 8, characterised in that: It also has boron nitride.

10. A polyamide 66 composite material as claimed in claim 9, characterised in that: The particle size of the boron nitride is 4-6 μm.