Flame-retardant PA66 composition and preparation method thereof

Abstract

The invention relates to the field of high polymer materials, in particular to a flame-retardant PA66 composition and a preparation method thereof. Specifically, the flame-retardant PA66 composition is prepared from PA66, PPE (Polypropylene), fumaric acid grafted PPE, a flame retardant, SEBS (Styrene-Ethylene-Butylene-Styrene) and dopamine modified multi-walled carbon nanotubes. According to the invention, the fumaric acid grafted PPE and the dopamine modified multi-walled carbon nanotubes are used in the PPE, so that the interface energy between the components, especially the environment-friendly organophosphorus flame retardant Exolide OP 1312 and the PA66 is effectively reduced, and the mechanical properties of the PA66 composition are still maintained while the high addition amount of the flame retardant is realized.

Description

Technical Field

[0001] This application relates to the field of polymer materials. More specifically, it relates to a flame-retardant PA66 composition and its preparation method. Background Art

[0002] PA66 (polyamide 66) is a high-performance engineering plastic and is widely used in many fields due to its excellent mechanical properties, heat resistance, and chemical stability. It has high strength, high toughness, and good wear resistance, and can still maintain stable properties in high-temperature environments. The melting point of PA66 is as high as 250 - 265 °C, and the heat distortion temperature is above 200 °C, making it suitable for manufacturing products such as automotive engine components, electronic and electrical enclosures, and mechanical parts that need to withstand high temperatures and mechanical stresses. In addition, by adding flame retardants, PA66 can also meet strict fire requirements, further expanding its applications in high-end fields such as aerospace, 5G communication, and new energy vehicles.

[0003] Poly(2,6-dimethyl-1,4-phenylene ether) (PPE), with its high glass transition temperature of 207 °C, excellent impact resistance, dimensional stability, heat resistance, and flame retardancy, has become an ideal engineering plastic for high-temperature applications. However, the ultra-high melt viscosity of PPE significantly increases its processing difficulty, which has become a major bottleneck in its application. To solve this problem, the blend system of PPE and PA66 has emerged, and this combination is expected to integrate the high flame retardancy and mechanical toughness of PPE and the excellent processing performance of PA66. Unfortunately, the incompatibility between PPE and PA66 and the poor heat resistance of PA66 itself not only weaken the mechanical properties of PPE but also reduce its flame retardant effect. At the same time, when flame retardants are added, the mechanical properties of the composition itself also significantly decrease. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a flame-retardant PA66 composition and its preparation method.

[0005] A flame-retardant PA66 composition, comprising PA66, PPE, maleic anhydride-grafted PPE, flame retardant, SEBS, and dopamine-modified multi-walled carbon nanotubes.

[0006] PPE, poly(2,6-dimethyl-1,4-phenylene ether) is a typical engineering plastic suitable for high-temperature applications, having a high glass transition temperature of 207 °C, good impact strength, good dimensional stability, excellent heat resistance, and excellent flame retardancy.

[0007] Maleic anhydride-grafted PPE and dopamine-modified multi-walled carbon nanotubes as solubilizers can improve the compatibility of PA66, PPE, and flame retardants, and while improving the flame retardancy, also improve the mechanical properties.

[0008] Further, by weight parts, there are 40 - 60 parts of PA66, 50 - 60 parts of PPE, 2 - 10 parts of maleic acid grafted PPE, 2 - 20 parts of flame retardant, 20 parts of SEBS, and 2 - 6 parts of dopamine modified multi - walled carbon nanotubes.

[0009] Further, there are 50 parts of PA66, 60 parts of PPE, 6 parts of maleic acid grafted PPE, 28 parts of flame retardant, 20 parts of SEBS, and 2 - 6 parts of dopamine modified multi - walled carbon nanotubes.

[0010] Further, the flame retardant is selected from Exolit OP 1312.

[0011] The halogen - free flame retardant Exolit OP 1312 promotes the formation of a carbon layer on the surface of the polymer during combustion. The carbon layer blocks or delays the diffusion of oxygen to the polymer and inhibits combustion, which is called achieving flame retardancy through solid - phase reaction. No toxic and carcinogenic gases such as dioxins or furans are produced during combustion.

[0012] Further, the preparation method of the maleic acid grafted PPE is as follows:

[0013] Mix PPE, HIPS, maleic acid, and DCP in a high - speed mixer at a stirring speed of 100 r / min for 10 min, and then extrude at 310 °C through a twin - screw extruder to obtain maleic acid grafted PPE.

[0014] Further, the mass ratio of PPE, HIPS, maleic acid, and DCP is 92:5:3:0.3.

[0015] Further, the preparation method of the dopamine modified multi - walled carbon nanotubes is as follows:

[0016] Step S1: Add 1 g of carboxylated multi - walled carbon nanotubes and 1 g of hydrochloric acid dopamine to 100 mL of deionized water and sonicate for 2 h;

[0017] Step S2: Disperse 0.8 g of EDC and 0.4 g of NHS in 20 mL of deionized water, and then drop - wise add them to the dispersion obtained in Step S1; then react at 80 °C for 24 h; after natural cooling, dry in a vacuum drying oven for 24 h to obtain dopamine modified multi - walled carbon nanotubes.

[0018] Further, the present invention also provides a preparation method of a flame - retardant PA66 composition, which is characterized by including the following steps:

[0019] Weigh each raw material according to the parts by weight, dry them separately, and mix them in a high-speed mixer at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder for melt extrusion; the screw speed is 200 r / min; after pelletizing, a flame-retardant PA66 composition is obtained. Further, the temperature range for melt extrusion is: zone 1 at 255 °C, zone 2 at 265 °C, and zone 3 at 275 °C. The screw speed for melt extrusion is 200 r / min.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] In the present invention, by using fumaric acid-grafted PPE and dopamine-modified multi-walled carbon nanotubes in PPE, the interfacial energy between each component, especially between the environmentally friendly organophosphorus flame retardant Exolit OP 1312 and PA66, is effectively reduced, so that while maintaining a high addition amount of the flame retardant, the mechanical properties of the PA66 composition are still maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not limit the embodiments of the present invention.

[0023] Figure 1 It is a TEM image of the flame-retardant PA66 composition in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are not intended to limit the present invention.

[0025] Exolit OP 1312 is purchased from Clariant and is a non-halogenated flame retardant based on organic phosphinates. This product achieves its flame retardant effect through expansion. Thermoplastic polymers with Exolit OP 1312 foam and crosslink when exposed to flame and form a stable carbon layer on the surface as a barrier. The protective layer provides heat insulation, reduces oxygen ingress, and prevents molten polymer dripping.

[0026] SEBS: Styrene-ethylene-styrene block copolymer, purchased from Taipol 6151 of Taizhou Rubber;

[0027] Carboxylated multi-walled carbon nanotubes: purchased from sigma, product number 755125;

[0028] PPE: Poly(2,6-dimethyl-1,4-phenylene oxide), CAS: 25134-01-4;

[0029] HIPS: High impact polystyrene, purchased from BASF;

[0030] DCP: Dicumyl peroxide, CAS: 80-43-3

[0031] EDC: 1-Ethyl-(3-dimethylaminopropyl)carbodiimide; CAS: 1892-57-5;

[0032] NHS: N-Hydroxysuccinimide, CAS: 6066-82-6.

[0033] The preparation method of fumaric acid grafted PPE in the present invention is as follows: Mix 92 parts of PPE, 5 parts of HIPS, 3 parts of fumaric acid, and 0.3 parts of DCP by weight in a high-speed mixer at a stirring speed of 100 r / min for 10 min, and then extrude through a twin-screw extruder at 310 °C to obtain fumaric acid grafted PPE.

[0034] The preparation method of dopamine modified multi-walled carbon nanotubes in the present invention:

[0035] Step S1:: Add 1 g of carboxylated multi-walled carbon nanotubes and 1 g of hydrochloric acid dopamine to 100 mL of deionized water and sonicate for 2 h;

[0036] Step S2: Disperse 0.8 g of EDC and 0.4 g of NHS in 20 mL of deionized water, and then add dropwise to the dispersion obtained in Step S1; then react at 80 °C for 24 h; after natural cooling, dry in a vacuum drying oven for 24 h to obtain dopamine modified multi-walled carbon nanotubes.

[0037] Example 1

[0038] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 6 parts of fumaric acid grafted PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 2 parts of dopamine modified multi-walled carbon nanotubes.

[0039] A preparation method of a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them respectively, mix them in a high-speed mixer at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder and carry out melt extrusion. The melt extrusion temperature range is: zone 1 255 °C, zone 2 265 °C, zone 3 275 °C; the screw speed is 200 r / min; after granulation, a flame-retardant PA66 composition is obtained. Figure 1 This is the TEM image of the flame-retardant PA66 composition in this example.

[0040] Example 2

[0041] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 6 parts of maleic acid-grafted PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 3 parts of dopamine-modified multi-walled carbon nanotubes.

[0042] A method for preparing a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them separately, mix them in a high-speed mixer at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder, and carry out melt extrusion. The melt extrusion temperature range is: zone 1 at 255 °C, zone 2 at 265 °C, zone 3 at 275 °C; the screw speed is 200 r / min; after granulation, a flame-retardant PA66 composition is obtained.

[0043] Example 3

[0044] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 6 parts of maleic acid-grafted PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 4 parts of dopamine-modified multi-walled carbon nanotubes.

[0045] A method for preparing a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them separately, mix them in a high-speed mixer at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder, and carry out melt extrusion. The melt extrusion temperature range is: zone 1 at 255 °C, zone 2 at 265 °C, zone 3 at 275 °C; the screw speed is 200 r / min; after granulation, a flame-retardant PA66 composition is obtained.

[0046] Example 4

[0047] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 6 parts of maleic acid-grafted PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 5 parts of dopamine-modified multi-walled carbon nanotubes.

[0048] A method for preparing a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them separately, mix them in a high-speed mixer at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder, and carry out melt extrusion. The melt extrusion temperature range is: zone 1 at 255 °C, zone 2 at 265 °C, zone 3 at 275 °C; the screw speed is 200 r / min; after granulation, a flame-retardant PA66 composition is obtained.

[0049] Example 5

[0050] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 6 parts of maleic acid-grafted PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 6 parts of dopamine-modified multi-walled carbon nanotubes.

[0051] A preparation method of a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them respectively, mix them in a high-speed blender, the stirring speed is 100 r / min, and stir and mix for 10 min; then put the mixed raw materials into a twin-screw extruder, and carry out melt extrusion. The melt extrusion temperature range is: the first zone is 255 °C, the second zone is 265 °C, and the third zone is 275 °C; the screw speed is 200 r / min; after pelletizing, a flame-retardant PA66 composition is obtained.

[0052] Comparative Example 1

[0053] A flame-retardant PA66 composition, by weight, includes: 50 parts of PA66, 60 parts of PPE, 8 parts of Exolit OP 1312, 20 parts of SEBS, and 4 parts of multi-walled carbon nanotubes.

[0054] A preparation method of a flame-retardant PA66 composition: Weigh each raw material according to the weight parts, dry them respectively, mix them in a high-speed blender, the stirring speed is 100 r / min, and stir and mix for 10 min; then put the mixed raw materials into a twin-screw extruder, and carry out melt extrusion. The melt extrusion temperature range is: the first zone is 255 °C, the second zone is 265 °C, and the third zone is 275 °C; the screw speed is 200 r / min; after pelletizing, a flame-retardant PA66 composition is obtained.

[0055] Test Example 1

[0056] The impact strength is tested according to ASTM D256.

[0057] The tensile property test is carried out according to ASTM D638, and the tensile speed is 10 mm / min.

[0058] Table 1 Performance test of examples and comparative examples

[0059] Tensile strength (MPa) <![CDATA[Impact strength KJ / m 2 > Elongation at break (%) Example 1 43.5 9.4 25 Example 2 45.2 15.7 23 Example 3 49.7 29.3 22 Example 4 47.4 18.4 17 Example 5 42.1 6.2 14 Comparative Example 1 41.6 9.1 23

[0060] As can be seen from Table 1, the data in the table show that the tensile strength (49.7 MPa) and impact strength (29.3 KJ / m 2) and the elongation at break (22%) are the highest or close to the highest values among the examples, showing excellent comprehensive mechanical properties; while in Comparative Example 1, when dopamine-modified multi-walled carbon nanotubes were not used, the performance decreased significantly. Therefore, in the present invention, by using fumaric acid-grafted PPE and dopamine-modified multi-walled carbon nanotubes in PPE, the interfacial energy between each component, especially between the environmentally friendly organophosphorus flame retardant Exolit OP 1312 and PA66, is effectively reduced, enabling the mechanical properties of the PA66 composition to be maintained while the flame retardant is added in a high amount.

[0061] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flame-retardant PA66 composition, characterized in that, It includes PA66, PPE, maleic anhydride-grafted PPE, flame retardant, SEBS, and dopamine-modified multi-walled carbon nanotubes.

2. The flame-retardant PA66 composition according to claim 1, wherein, Calculated by weight parts, there are 40 - 60 parts of PA66, 50 - 60 parts of PPE, 2 - 10 parts of maleic anhydride-grafted PPE, 2 - 20 parts of flame retardant, 20 parts of SEBS, and 2 - 6 parts of dopamine-modified multi-walled carbon nanotubes.

3. The flame-retardant PA66 composition according to claim 2, wherein Calculated by weight parts, there are 50 parts of PA66, 60 parts of PPE, 6 parts of maleic anhydride-grafted PPE, 28 parts of flame retardant, 20 parts of SEBS, and 2 - 6 parts of dopamine-modified multi-walled carbon nanotubes.

4. The flame-retardant PA66 composition according to claim 3, characterized in that, The flame retardant is selected from Exolit OP1312.

5. The flame-retardant PA66 composition according to claim 1, characterized in that, The preparation method of the maleic anhydride-grafted PPE is as follows: Mix PPE, HIPS, maleic anhydride, and DCP in a high-speed blender at a stirring speed of 100 r / min for 10 min, and then extrude at 310 °C through a twin-screw extruder to obtain maleic anhydride-grafted PPE.

6. The flame-retardant PA66 composition according to claim 5, wherein The mass ratio of PPE, HIPS, maleic anhydride, and DCP is 92:5:3:0.

3.

7. The combustion-type PA66 composition according to claim 1, wherein The preparation method of the dopamine-modified multi-walled carbon nanotubes is as follows: Step S1: Add 1 g of carboxylated multi-walled carbon nanotubes and 1 g of hydrochloric acid dopamine to 100 mL of deionized water and ultrasonicate for 2 h. Step S2: Disperse 0.8 g of EDC and 0.4 g of NHS in 20 mL of deionized water, and then gradually add it to the dispersion obtained in Step S1; then react at 80 °C for 24 h; after natural cooling, dry it in a vacuum drying oven for 24 h to obtain dopamine-modified multi-walled carbon nanotubes.

8. The preparation method of the flame-retardant PA66 composition according to any one of claims 1 to 7, characterized in that, It includes the following steps: Weigh each raw material according to the weight parts, dry them respectively, mix them in a high-speed blender at a stirring speed of 100 r / min for 10 min; then put the mixed raw materials into a twin-screw extruder for melt extrusion; the screw speed is 200 r / min; after pelletizing, a flame-retardant PA66 composition is obtained.

9. The preparation method according to claim 8, characterized in that, The temperature range of melt extrusion is: zone 1 at 255 °C, zone 2 at 265 °C, and zone 3 at 275 °C.

10. The preparation method according to claim 9, characterized in that, The screw speed of the melt extrusion is 200 r / min.

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