CN115418102A

CN115418102A - Halogen-free flame-retardant PA66 material with high GWIT and high CTI and preparation method thereof

Info

Publication number: CN115418102A
Application number: CN202211170983.4A
Authority: CN
Inventors: 张文证; 李静
Original assignee: Suzhou Kingchen Plastic Technology Co ltd
Current assignee: Suzhou Kingchen Plastic Technology Co ltd
Priority date: 2022-09-24
Filing date: 2022-09-24
Publication date: 2022-12-02
Anticipated expiration: 2042-09-24
Also published as: CN115418102B

Abstract

The application relates to the field of plastics, in particular to a high-GWIT high-CTI halogen-free flame-retardant PA66 material and a preparation method thereof, wherein the high-GWIT high-CTI halogen-free flame-retardant PA66 material is prepared from the following raw materials in parts by weight: the feed is prepared from the following raw materials in parts by weight: 70-80 parts of PA66 resin, 20-30 parts of flame retardant, 0.3-0.7 part of EBS, 0.1-0.3 part of calcium stearate, 0.3-0.5 part of zinc stearate and 0.1-0.5 part of antioxidant; the flame retardant is expandable graphite/modified vermiculite. According to the application, the modified vermiculite and the expandable graphite are compounded to form the expandable graphite/modified vermiculite as the flame retardant, so that the flame retardance and the mechanical property of the PA66 material are improved, and the influence of the flame retardant on CTI is reduced, so that the product has high GWIT and CTI at the same time.

Description

Halogen-free flame-retardant PA66 material with high GWIT and CTI and preparation method thereof

Technical Field

The application relates to the technical field of plastics, in particular to a halogen-free flame retardant PA66 material with high GWIT and high CTI and a preparation method thereof.

Background

PA66 (nylon 66) is one of engineering plastics which are applied more at present, and is widely applied to the fields of household appliances, electric appliances, new energy automobile chargers, charging guns, battery related control systems and the like due to good mechanical strength, wear resistance, corrosion resistance and molding processability.

However, PA66 has an oxygen index of only about 22%, so that when it is heated and burned, it is particularly easy to generate a molten drop phenomenon, thereby igniting other combustible materials. The current flame retardant products of PA66 can be roughly divided into two series of halogen flame retardant and halogen-free flame retardant. The halogenated flame retardant is mainly a bromine-antimony compound flame retardant, but the halogenated flame retardant has toxicity and is not suitable for use and popularization; the halogen-free flame retardant mainly comprises red phosphorus flame retardant, diethyl aluminum phosphinate flame retardant and nitrogen flame retardant, wherein the red phosphorus flame retardant has use limitation due to the problem of color, and the diethyl aluminum phosphinate flame retardant is difficult to popularize due to the problem of cost. The nitrogen-based flame retardant can produce side effect on CTI of the product, and the CTI of the product is reduced.

In conclusion, the flame retardant systems cannot meet the requirements of certain electronic products with high GWIT and CTI requirements, and the use and development of the electronic products are limited.

Disclosure of Invention

In order to reduce the influence of a flame retardant in a PA66 material on a CTI product and meet the requirements of the product on high GWIT and CTI, the application provides a halogen-free flame-retardant PA66 material with high GWIT and high CTI and a preparation method thereof.

In a first aspect, the application provides a halogen-free flame retardant PA66 material with high GWIT and high CTI, which adopts the following technical scheme:

a halogen-free flame retardant PA66 material with high GWIT and CTI comprises the following raw materials in parts by weight: the feed is prepared from the following raw materials in parts by weight: 70-80 parts of PA66 resin, 20-30 parts of flame retardant, 0.3-0.7 part of EBS, 0.1-0.3 part of calcium stearate, 0.3-0.5 part of zinc stearate and 0.1-0.5 part of antioxidant; the fire retardant is expandable graphite/modified vermiculite.

By adopting the technical scheme, the vermiculite has excellent high temperature resistance, and can still maintain the original structure and strength at the high temperature of 100 ℃. The vermiculite is an excellent flame retardant material due to the high content of interlayer water and structural water, the water vapor released when the material is heated plays a flame retardant role, and the good high temperature resistance and the unique nano-layer structure of the material are proved; the vermiculite is modified, so that a large number of uniform nano micropores are formed in the vermiculite layer, the vermiculite adsorption layer has good adsorbability, and the compressive strength of the vermiculite is improved.

The expandable graphite has high temperature resistance, namely, the expandable graphite rapidly expands at high temperature to suffocate flame, and meanwhile, the generated graphite expansion body material covers the surface of the base material to isolate the contact of heat energy radiation and oxygen, acid radicals in an interlayer of the expandable graphite are released when expanding, so that the carbonization of the base material is promoted, and the expandable graphite has good flame-retardant effect; meanwhile, the expandable graphite has abundant pore structures, so that the expandable graphite has excellent adsorption performance.

According to the application, the expandable graphite/modified vermiculite is formed by combining the modified vermiculite and the expandable graphite which both have adsorption performance, so that the combinability is good, and the synergistic flame retardant effect is favorably improved; expandable graphite/modified vermiculite is added into a PA66 material as a flame retardant, so that the flame retardance of the material is improved, the influence on a CTI index is reduced, and the GWIT and the CTI of a product are improved; does not contain toxic and harmful halogen components, and improves the use safety.

Preferably, the preparation method of the expandable graphite/modified vermiculite comprises the following steps:

crushing raw ore vermiculite, and screening to 100-300 meshes to obtain vermiculite powder; adding the vermiculite powder into an acidic solution, and heating and stirring to obtain a solid-liquid mixture; drying and grinding the solid obtained by filtering the solid-liquid mixture to obtain modified vermiculite powder;

expandable graphite and the modified vermiculite powder are mixed according to the mass ratio of (2-20): 1, uniformly mixing to obtain a mixture, dispersing the mixture into deionized water, and performing ultrasonic treatment to obtain a pasty solution, wherein the mass ratio of the mixture to the deionized water is 1: (5-15); performing ball milling on the pasty solution to obtain a turbid liquid; and standing the turbid liquid for 20-30h, removing supernatant liquid, and drying to constant weight to obtain the expandable graphite/modified vermiculite.

By adopting the technical scheme, the expandable graphite/modified vermiculite is prepared by taking the modified vermiculite and the expandable graphite as raw materials and adopting a mechanical ball milling method, the preparation method is simple to operate, the conditions are mild, and other toxic solvents are not required; meanwhile, the prepared expandable graphite/modified vermiculite has excellent binding property and flame retardant property.

Preferably, the drying temperature is 80-100 ℃, and the drying time is 8-12h.

By adopting the technical scheme, the temperature and time during drying are optimized, so that the preparation efficiency can be improved, and the prepared expandable graphite/modified vermiculite has excellent flame retardant property.

Preferably, the average particle size of the expandable graphite/modified vermiculite is less than 1 μm, and the thickness is 3-4nm.

By adopting the technical scheme, the size of the expandable graphite/modified vermiculite is controlled, so that the uniformity of the expandable graphite/modified vermiculite in mixing with other components in the PA66 can be improved, and the comprehensive performance of the PA66 material is further improved.

Preferably, the antioxidant is a mixture of an antioxidant 1098 and an antioxidant 168, and the mass ratio of the antioxidant 1098 to the antioxidant 168 is (1-3): 1.

by adopting the technical scheme, the antioxidant 1098 is an excellent extraction-resistant low-volatility hindered phenol antioxidant, and has the characteristics of good thermal stability, compatibility, no initial coloring, no pollution and extraction resistance; when the composite material is acted on PA66, the oxidation resistance and the thermal stability are particularly outstanding. The antioxidant 168 is used as an auxiliary antioxidant and is combined with an antioxidant 1098 phenolic antioxidant to have synergistic effect; meanwhile, the antioxidant property of the antioxidant 1098 is prolonged.

Preferably, the anti-dripping agent also comprises 0.1-1 weight part of anti-dripping agent.

Through adopting above-mentioned technical scheme, anti-dripping agent is through extruding screw rod shearing action fiberization, forms network structure in the PA66 material, and the material is heated the shrink and is prevented that the material melts the drippage when burning, can further improve the fire resistance of PA66 material.

Preferably, the anti-dripping agent is one of C60 fullerene, C70 fullerene and silicon carbide whisker.

By adopting the technical scheme, the fullerene is in a fourth crystal form of carbon elements after the diamond, the graphite and the linear carbon; the silicon carbide whisker has excellent high temperature resistance and high strength. Compared with the traditional polytetrafluoroethylene anti-dripping agent, the fullerene and silicon carbide whisker used as the antibacterial dripping agent have better effect than the traditional anti-dripping agent under the condition of the same content.

Preferably, the diameter D of the silicon carbide whisker is 0.5-1.5 μm, and the length-diameter ratio L/D is (20-30): 1.

by adopting the technical scheme, on one hand, the silicon carbide whiskers with proper length-diameter ratio can be fully dispersed in the PA66 material, and the excellent heat resistance of the whiskers is exerted; meanwhile, due to the surface energy and the electrostatic action of the silicon carbide whiskers, the whiskers can generate an agglomeration phenomenon, particularly long whiskers can also be tangled, and further the advantages of the silicon carbide whiskers are reduced. On the other hand, the silicon carbide whiskers are not too thin, and especially when the service environment has an oxidizing atmosphere, the proper increase of the diameter of the silicon carbide whiskers is beneficial to improving the oxidation resistance of the silicon carbide whiskers and improving the service temperature and the compatibility of the service environment of the PA66 material.

In a second aspect, the application provides a preparation method of a halogen-free flame retardant PA66 material with high GWIT and high CTI, which adopts the following technical scheme:

a preparation method of a halogen-free flame-retardant PA66 material with high GWIT and CTI adopts the following technical scheme:

uniformly mixing the raw materials in corresponding parts by weight to obtain a mixture;

and performing melt extrusion on the mixture and granulating.

By adopting the technical scheme, the preparation method has simple process, does not need special equipment and is suitable for industrial production; meanwhile, the prepared PA66 material has excellent flame retardance and environmental protection advantages, has good environmental compatibility, and is particularly favorable for being applied to the fields of household electrical appliances, electronic appliances, new energy automobile chargers, charging guns, battery related control systems and the like.

Preferably, a parallel double-screw extruder is adopted when the mixture is subjected to melt extrusion, the shape of the screw is double-thread, and the ratio L/D of the length L of the screw to the diameter D of the screw is 30-40.

By adopting the technical scheme, the double-thread screw has large lead, short material retention time during extrusion, reduced material degradation and improved production efficiency; meanwhile, the double-thread screw has higher plasticizing and dispersing capacity than a single-thread screw, and the dispersion degree of the expandable graphite/modified vermiculite is improved. The too large length-diameter ratio of the screw can cause the polymer to be heated for a long time, the expandable graphite/modified vermiculite is degraded, and the manufacturing and installation of the screw and the extruder are increased; the length-diameter ratio of the screw is too small, and the poor dispersing ability is not favorable for improving the generation efficiency.

In summary, the present application includes at least one of the following beneficial technical effects:

1. according to the application, the mechanical strength of the modified vermiculite is improved by modifying the vermiculite, and the modified vermiculite with adsorbability and the expandable graphite are combined to form the expandable graphite/modified vermiculite flame retardant, so that the flame retardance of the PA66 material is improved, the influence on the CTI index is reduced, and the GWIT and the CTI of the product are improved;

2. the expandable graphite/modified vermiculite is prepared by adopting a mechanical ball milling method, the preparation method is simple, the conditions are mild, other toxic solvents are not required, and the safety and environmental friendliness are realized;

3. this application adds PA66 material with C60 fullerene, C70 fullerene, carborundum whisker as anti-dripping agent, forms network structure in the material during preparation, and the material is heated the shrink and is prevented that the material melting from dripping when burning, can further improve the fire behaviour of PA66 material.

Detailed Description

The present application is described in further detail below with reference to preparation examples and examples.

Preparation example

Preparation example 1

The preparation example discloses a preparation method of expandable graphite/modified vermiculite, which specifically comprises the following steps:

s10, selecting raw ore vermiculite with the particle size of 0.7-2mm, crushing the raw ore vermiculite by a ball mill, and screening the raw ore vermiculite to 100-300 meshes to obtain vermiculite powder, wherein the raw ore vermiculite is purchased from Wanzhu mineral products Limited, lingshou county;

s20, adding H into the 30g of vermiculite powder ⁺ Raising the temperature to 100 ℃ in 1000ml of acid solution with the concentration of 6mol/L, and treating for 3 hours under rapid stirring to obtain a solid-liquid mixture;

s30, filtering the obtained solid-liquid mixture to obtain vermiculite solids, repeatedly washing the vermiculite solids with deionized water until the pH value of the washed deionized water is 7, drying the washed solids at 120 ℃ for 12 hours, and grinding the dried solids to obtain modified vermiculite powder;

s40, uniformly mixing 2g of expandable graphite and 1g of the modified vermiculite powder, adding the mixture into 15ml of deionized water, and performing ultrasonic dispersion in a water bath at 60 ℃ for 30min to form a pasty solution; then placing the graphene into a ball-milling tank containing zirconia, wherein the ball-to-material ratio is 30; standing for 20h, removing supernatant, drying in an oven at 80 deg.C for 12h to constant weight to obtain black powder with average particle diameter of less than 1 μm and thickness of 3-4nm, i.e. expandable graphite/modified vermiculite, which is 80 mesh, has an expansion degree of 300 and is purchased from Ningshou county Touda mineral processing factory.

Preparation example 2

Unlike preparation example 1, in S40, 10g of expandable graphite and 1g of the modified vermiculite powder were mixed uniformly and added to 110ml of deionized water.

Preparation example 3

Unlike preparation example 1, in S40, 20g of expandable graphite and 1g of the modified vermiculite powder were mixed uniformly and added to 315ml of deionized water.

Preparation example 4

The difference between the preparation example and the preparation example 1 is that in S40, the mixture is kept stand for 30 hours, supernatant liquid is removed, the mixture is placed into a 100 ℃ oven to be dried for 8 hours until the weight is constant, and the obtained black powder is expandable graphite/modified vermiculite.

Examples

Example 1

The embodiment discloses a halogen-free flame-retardant PA66 material with high GWIT and CTI (glow wire ignition temperature) which is prepared from 70KgPA66 resin, 20Kg of expandable graphite/modified vermiculite, 0.3Kg of EBS (ethylene bis stearamide), 0.1Kg of calcium stearate, 0.3Kg of zinc stearate, 0.05Kg of antioxidant 1098 and 0.05Kg of antioxidant 168, wherein the expandable graphite/modified vermiculite is prepared by adopting the preparation example 1, the PA66 resin is EPR27, the CAS of EBS: 110-30-5, calcium stearate CAS:1592-23-0, zinc stearate CAS:557-05-1, antioxidant 1098 CAS:23128-74-7, CAS for antioxidant 168: 1570-04-4.

The embodiment also discloses a preparation method of the halogen-free flame retardant PA66 material with high GWIT and high CTI, which comprises the following specific processes:

s1, weighing the components according to a formula, adding the components into a high-speed mixing machine, and uniformly mixing to obtain a mixture;

s2, adding the mixture into a parallel double-screw extruder, and granulating after melt extrusion to obtain a PA66 material; wherein the rotation speed of the twin-screw extruder is set to 400rpm/min, and the extrusion temperatures of the first to eighth zones are: 180 ℃/185 ℃/190 ℃/185 ℃/185 ℃/180 ℃/180 ℃; the temperature of the machine head is 200 ℃; the vacuum degree is-0.04 Mpa; the ratio L/D of the length L of the extruder screw to the diameter D was 30.

Examples 2 to 18

The difference between this example and example 1 is that the amount of the raw material used for the PA66 material is different, as shown in table 2.

TABLE 1 EXAMPLES 1-18PA66 Material proportioning of raw materials

Examples 19 to 21

This example is essentially the same as example 1, except that the expandable graphite/modified vermiculite was prepared using the same example, as shown in table 2. Table 2 examples 19-21 examples of preparations for expandable graphite/modified vermiculite

Example 22

This example is substantially the same as example 1, except that C60 fullerene is replaced with C70 fullerene, C60 fullerene and C70 fullerene CAS:131159-39-2, available from siennantai biotechnology limited.

Example 23

This example is substantially the same as example 1 except that C60 fullerene is replaced with silicon carbide whisker having a diameter D of 0.5 to 1.5 μm, a length L of 10 to 45 μm, and an aspect ratio L/D of (20 to 30): 1, purchased from shanghai lane field nanomaterials, inc.

Example 24

This example is substantially the same as the examples except that the ratio L/D of the length L of the extruder screw to the diameter D is 40.

Comparative example

Comparative example 1

This comparative example differs from example 1 mainly in that expandable graphite/modified vermiculite was replaced with expandable graphite.

Comparative example 2

This comparative example differs from example 1 mainly in that expandable graphite/modified vermiculite was replaced with modified vermiculite.

Comparative example 3

The comparative example differs from example 1 mainly in that the expandable graphite/modified vermiculite was replaced with expandable graphite in a preparation method in which vermiculite was not modified.

Comparative example 4

The main difference between this example and example 1 is that in the preparation method of replacing expandable graphite/modified vermiculite with expandable graphite, in S40, 1g of expandable graphite and 1g of the above modified vermiculite powder are mixed uniformly and then added to 2ml of deionized water.

Comparative example 5

The main difference between this example and example 1 is that, in the preparation method of replacing expandable graphite/modified vermiculite with expandable graphite, in S40, 30g of expandable graphite and 1g of the above modified vermiculite powder are mixed uniformly and then added to 620ml of deionized water.

Comparative example 6

This example is mainly different from example 1 in that C60 fullerene is replaced with polytetrafluoroethylene-type anti-dripping agent, polytetrafluoroethylene-type dripping agent CAS:9002-84-0, available from south sea silver Provisions trade, inc., of Foshan City.

Performance testing the PA66 materials obtained in examples 1 to 24 were used as test samples 1 to 24, and the PA66 materials obtained in comparative examples 1 to 6, which had the same weight as the test samples, were used as control samples 1 to 6. The test sample and the control sample are subjected to performance tests, the results are shown in table 3, and the specific test process is as follows:

flame resistance: the 1.6mm thick bars were tested in accordance with UL94 standard.

GWIT:1.6mm thick bars were tested according to IEC60695 standard.

CTI: the sample was 2X 4mm and tested according to IEC60112, 0.1% anhydrous ammonium chloride was selected as electrolyte and the calibration current was 1A.

Tensile strength: the test was performed with reference to the ASTM D638 standard.

Bending strength: the test was performed with reference to ASTM D790 standard.

Notched impact strength: the test was performed with reference to the ASTM D256 standard.

Oxidation resistance: the color fastness is tested according to SAE J2527 with high light color spot, and the irradiation dose is 2500kJ/m ² And testing the chromatic aberration delta E.

TABLE 3 Performance test data sheet

Referring to table 3, in combination with examples 1 to 3, it can be seen that the mechanical properties of the test specimen are improved with the increasing content of the PA66 resin, but the flame retardancy and GWIT of the PA66 material are reduced due to the poor flame retardancy of the PA66 resin.

Referring to table 3, in conjunction with examples 2, 4 and 5, it can be seen that the fire retardancy and GWIT of the samples are higher and higher with the addition of expandable graphite/modified vermiculite in the PA66 material. The strength of the vermiculite is improved by modifying the vermiculite, and the expandable/modified vermiculite formed by combining the modified vermiculite with the adsorption force and the expanded graphene has excellent flame retardant property, so that the flame retardance of the PA66 material is improved.

Referring to table 3, in conjunction with examples 4, 6 and 7, it can be seen that the addition of an appropriate amount of EBS to the PA66 material improves the overall performance of the sample. The EBS is added into the PA66 as a dispersing agent, so that the dispersibility and stability of the components can be promoted, the mixing property of the mixture is better, and the mechanical property, the flame retardance, the GWIT and the CTI of the sample are improved.

Referring to table 3, in combination with examples 6 and 8-11, it can be seen that the samples obtained by adding appropriate amounts of calcium stearate and zinc stearate to the PA66 material all have good mechanical properties and flame retardancy. The calcium stearate and the calcium stearate are added into the PA66 material as a lubricant, so that the lubricating agent has the effects of smoothness and processing, the processability of the PA66 material during extrusion molding is improved, the PA66 material has better free radical resistant compounding capability, and the lubricating agent has the promotion effect on the color stability and the corrosion resistance of the PA66 material.

Referring to table 3, in combination with examples 10, 12-15, it can be seen that the addition of appropriate amounts of antioxidant 1098 and antioxidant 168 to the PA66 material improves the oxidation resistance of the test specimens, particularly when the mass ratio of antioxidant 1098 to antioxidant 168 is 2:1 (example 12), the oxidation resistance of the sample is better than that of the antioxidant 1098 and the antioxidant 168 in the mass ratio of 1; with the increasing of the content of the antioxidant, the oxidation resistance of the sample is also improved. The antioxidant is added into the plastic resin, so that the thermal oxidation reverberation speed of plastic macromolecules is inhibited or reduced, the thermal and oxygen degradation process of the plastic comb is delayed, the heat-resistant function of the plastic resin can be obviously improved, the antioxidant 1098 is used as a main antioxidant, the antioxidant 1689 is used as a secondary antioxidant, and the antioxidant and the main antioxidant are combined for use, so that a good synergistic effect is achieved.

Referring to Table 3, in combination with examples 14 and 16 to 18, it can be seen that the flame retardancy of the test specimens can be improved by adding an appropriate amount of C60 fullerene to PA 66. The C60 fullerene is added into the PA66 as an anti-dripping agent, and after a network section is formed in the PA66 material, the material is heated to shrink and placed to be melted and dripped during combustion, so that the flame retardant effect of the sample can be further improved.

Referring to table 3, in combination with examples 1 and 19 to 20 and comparative examples 4 and 5, it can be seen that when expandable graphite/modified vermiculite is prepared, the mass ratio of the modified expandable graphite to the modified vermiculite and the mass ratio of the mixture of the two to deionized water are within appropriate ranges, and the obtained samples are more excellent in flame retardancy, GWIT and CTI.

Referring to table 3, in conjunction with examples 1, 21 and 24, it can be seen that by varying the process conditions for preparing the expandable graphite/modified vermiculite or the process parameters for preparing the PA66 material within the appropriate ranges, the resulting samples still have excellent overall properties.

Referring to table 3, in combination with examples 1, 22 and 23 and comparative example 6, it can be seen that the samples are excellent in flame retardancy, GWIT and CTI when C60 fullerene is replaced with C70 fullerene or silicon carbide whisker; however, when the C60 fullerene is replaced by the traditional polytetrafluoroethylene anti-dripping agent, the flame retardant effect of the sample is obviously reduced.

Referring to table 3, in combination with comparative examples 1 to 3 of example 1, it can be seen that modification of vermiculite can improve the strength and adsorbability of vermiculite, thereby improving the binding property of expanded graphite and modified vermiculite and the mechanical strength of the obtained flame retardant expanded graphite/modified vermiculite, and further improving the flame retardancy and mechanical effect of the PA66 material. Meanwhile, the modified vermiculite or the expanded graphite is independently used as a flame retardant to be added into the PA66 material, so that the comprehensive performance of the obtained sample is reduced more, and particularly the flame retardant performance, GWIT and CTI are outstanding.

The specific embodiments are only for explaining the present application and are not limiting to the present application, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but all the embodiments are protected by patent law within the scope of the claims of the present application.

Claims

1. A halogen-free flame retardant PA66 material with high GWIT and high CTI is characterized in that: the feed is prepared from the following raw materials in parts by weight: 70-80 parts of PA66 resin, 20-30 parts of flame retardant, 0.3-0.7 part of EBS, 0.1-0.3 part of calcium stearate, 0.3-0.5 part of zinc stearate and 0.1-0.5 part of antioxidant; the flame retardant is expandable graphite/modified vermiculite.

2. The high GWIT high CTI halogen-free flame retardant PA66 material as claimed in claim 1, wherein: the preparation method of the expandable graphite/modified vermiculite comprises the following steps:

expandable graphite and the modified vermiculite powder are mixed according to the mass ratio of (2-20): 1, uniformly mixing to obtain a mixture, dispersing the mixture into deionized water, and performing ultrasonic treatment to obtain a pasty solution, wherein the mass ratio of the mixture to the deionized water is 1: (5-15); ball-milling the pasty solution to obtain a suspension; and standing the turbid liquid for 20-30h, removing supernatant liquid, and drying to constant weight to obtain the expandable graphite/modified vermiculite.

3. The high GWIT high CTI halogen-free flame retardant PA66 material as claimed in claim 2, wherein: the drying temperature is 80-100 ℃, and the drying time is 8-12h.

4. The high GWIT high CTI halogen-free flame retardant PA66 material as claimed in claim 2, wherein: the average grain diameter of the expandable graphite/modified vermiculite is less than 1 mu m, and the thickness is 3-4nm.

5. The high GWIT high CTI halogen-free flame retardant PA66 material as claimed in claim 1, wherein: the antioxidant is a mixture of an antioxidant 1098 and an antioxidant 168, and the mass ratio of the antioxidant 1098 to the antioxidant 168 is (1-3): 1.

6. the high GWIT and high CTI halogen-free flame retardant PA66 material according to claim 1, characterized in that: also comprises 0.1-1 weight part of anti-dripping agent.

7. The high GWIT and high CTI halogen-free flame retardant PA66 material according to claim 6, characterized in that: the anti-dripping agent is one of C60 fullerene, C70 fullerene and silicon carbide whisker.

8. The high GWIT high CTI halogen-free flame retardant PA66 material as claimed in claim 7, wherein: the diameter D of the silicon carbide whisker is 0.5-1.5 μm, and the length-diameter ratio L/D is (20-30): 1.

9. the preparation method of the halogen-free flame retardant PA66 material with high GWIT and high CTI as claimed in any one of claims 1 to 8, characterized in that:

and performing melt extrusion on the mixture and granulating.

10. The preparation method of the halogen-free flame retardant PA66 material with high GWIT and high CTI according to claim 9, characterized in that: when the mixture is subjected to melt extrusion, a parallel double-screw extruder is adopted, the shape of the screw is double-thread, and the ratio L/D of the length L of the screw to the diameter D of the screw is (30-40): 1.