Polyamide composite material as well as preparation method and application thereof

Abstract

The invention discloses a polyamide composite material as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. The invention provides a polyamide composite material. The polyamide composite material comprises the following components in parts by weight: 30-50 parts of polyamide resin, 30-60 parts of hexagonal flaky magnesium hydroxide, 5-20 parts of magnesium hydroxide whiskers and 0-3 parts of a processing aid. According to the invention, the hexagonal flaky magnesium hydroxide with a specific particle size, a specific side length and a specific thickness ratio and the magnesium hydroxide whisker with a specific length-diameter ratio cooperate with each other, and the magnesium hydroxide whisker with the specific length-diameter ratio plays a role in constructing a heat conduction channel in the normal direction, so that the heat conductivity can be improved, and the mechanical property can also be improved; by combining hexagonal flaky magnesium hydroxide with a specific D50 particle size and a specific side length-thickness ratio, the heat conduction and mechanical properties of the polyamide composite material are jointly improved through cooperation of the two components, and the flame retardant property is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyamide composite material, a preparation method thereof and an application thereof. Background Art

[0002] As a high-performance engineering plastic, thermally conductive nylon combines the inherent strength, wear resistance and high melting point characteristics of nylon. By adding thermally conductive fillers such as graphite, silicon carbide, metal powder, boron nitride, magnesium hydroxide, etc., its thermal conductivity is significantly enhanced, making it show unique advantages in the fields of electronic appliances, automobiles, LED lighting, etc. Compared with metals, thermally conductive nylon has the advantages of low cost, free design and low density. However, a high filling amount of high-thermal-conductivity fillers usually causes disadvantages such as difficult extrusion processing and poor mechanical properties. Therefore, how to balance the mechanical properties and thermal conductivity of thermally conductive nylon has always been a pain point in the industry. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a polyamide composite material, a preparation method thereof and an application thereof.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a polyamide composite material, comprising the following components in parts by weight: 30-50 parts of polyamide resin, 30-60 parts of hexagonal flake magnesium hydroxide, 5-20 parts of magnesium hydroxide whiskers, and 0-3 parts of processing aids; wherein, the D50 particle size of the hexagonal flake magnesium hydroxide is 1-3.5 μm, and the ratio of the side length to the thickness of the hexagonal flake magnesium hydroxide is (2-25):1; the aspect ratio of the magnesium hydroxide whiskers is (50-150):1, and the average length is 40-180 μm.

[0005] Preferably, the weight percentage content of the polyamide resin in the polyamide composite material is not less than 25%.

[0006] In the present invention, through the synergy of hexagonal flake magnesium hydroxide and magnesium hydroxide whiskers, the magnesium hydroxide whiskers with a specific aspect ratio play a role in constructing a thermal conduction channel in the normal direction, which can not only improve the thermal conductivity but also improve the mechanical properties; combined with the hexagonal flake magnesium hydroxide with a specific D50 particle size and a specific ratio of side length to thickness, the two synergistically improve the thermal conductivity and mechanical properties of the polyamide composite material, and further improve the flame retardancy.

[0007] Preferably, the magnesium hydroxide is hexagonal flake, the side length of the magnesium hydroxide is the average side length of the hexagonal flake magnesium hydroxide, and the thickness of the magnesium hydroxide is the average thickness of the hexagonal flake magnesium hydroxide.

[0008] Preferably, the polyamide composite material comprises the following components in parts by weight: 35-45 parts of polyamide resin, 40-50 parts of hexagonal flake magnesium hydroxide, 10-15 parts of magnesium hydroxide whiskers, and 0-3 parts of processing aids.

[0009] Preferably, the D50 particle size of the hexagonal flake magnesium hydroxide is 1.5-2.5 μm, and the ratio of the side length to the thickness is (2-15):1.

[0010] Preferably, the aspect ratio of the magnesium hydroxide whiskers is (80-100):1, and the average length is 90-130 μm.

[0011] In one embodiment, the D50 particle size of the hexagonal flake magnesium hydroxide is measured by a laser particle size analyzer; the thickness and side length of the hexagonal flake magnesium hydroxide are observed by a scanning electron microscope, and 50 magnesium hydroxide particles are randomly selected to test the average values of the thickness and side length.

[0012] In one embodiment, the length and diameter of the magnesium hydroxide whiskers are observed by a scanning electron microscope, and 50 magnesium hydroxide whiskers are randomly selected to test the average values of the length and diameter.

[0013] Preferably, the relative viscosity of the polyamide resin is 1.5-2.8.

[0014] The magnesium hydroxide whiskers used in the present invention can be sourced from commercially available products or prepared in-house.

[0015] In one embodiment, the relative viscosity of the polyamide resin is one of 1.5, 2.0, 2.2, 2.5, 2.8 or a range value of any two of them.

[0016] Preferably, the processing aid is at least one of an antioxidant and a lubricant.

[0017] In one embodiment, the weight part of the antioxidant is 0.1-3 parts; the antioxidant is at least one of a hindered phenol antioxidant, a phosphite antioxidant, an amine antioxidant, and a copper halide composite antioxidant.

[0018] In one embodiment, the weight part of the lubricant is 0.1-3 parts, and the lubricant is at least one of a hydrocarbon lubricant, an ester lubricant, an alcohol lubricant, a fatty acid lubricant, a fatty acid amide lubricant, and a metal soap lubricant.

[0019] In one embodiment, the hindered phenol antioxidant includes at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and tris(ethylene glycol) bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate]; the phosphite antioxidant includes at least one of (2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, 2,2’,2”-nitrilotris(ethylidyne-3,3’,5,5’-tetra-tert-butyl-1,1’-biphenyl-2,2’-diyl) phosphite, tetra(2,4-di-tert-butylphenyl-4,4' biphenyl) diphosphite, tetra(2,4-di-tert-butylphenyl)-4,3’-diphenylene diphosphonate, and tetra(2,4-di-tert-butylphenyl)-3 or 3’-diphenylene diphosphonate.

[0020] In addition, the present invention provides a method for preparing the polyamide composite material, comprising the following steps:

[0021] (1) Weigh each component by weight parts;

[0022] (2) Mix the polyamide resin, hexagonal flake magnesium hydroxide, and processing aids, then add them into an extruder for melt dispersion. The magnesium hydroxide whiskers are added into the extruder through a side feeding port, and then extruded and pelletized to obtain the polyamide composite material.

[0023] In one embodiment, the screw speed of the twin-screw extruder is 300 - 800 rpm, the length-diameter ratio is 36:1 - 48:1, the temperature of each section of the barrel of the extruder is 160°C - 270°C, and the head temperature is 240°C - 280°C.

[0024] Furthermore, the present invention provides the application of the polyamide composite material in electronic appliances, automobiles, and LED lighting. The present invention provides the application of the polyamide composite material in energy-saving lamps and high thermal conductivity connectors.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: By synergistically combining hexagonal flake magnesium hydroxide with a specific particle size, a specific ratio of side length to thickness, and magnesium hydroxide whiskers with a specific aspect ratio, the magnesium hydroxide whiskers play a role in constructing a heat conduction channel in the normal direction, which can not only improve the heat conductivity but also enhance the mechanical properties. In combination with hexagonal flake magnesium hydroxide with a specific particle size and a specific ratio of side length to thickness, the two work together to improve the heat conduction and mechanical properties of the polyamide composite material, and further enhance the flame retardant performance. Detailed Embodiments

[0026] To better illustrate the purpose, technical solutions, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. The experimental reagents and instruments designed in the embodiments and comparative examples of the present invention are all common ordinary reagents and instruments, unless otherwise specified, and can all be obtained through commercial channels. In the embodiments and comparative examples, the experimental methods used are all conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0027] The raw materials used in the examples and comparative examples are described as follows, but are not limited to these materials:

[0028] Polyamide resin - 1: PA6 M2000, relative viscosity 2.0, manufacturer: Guangdong Xinhui Meida Nylon Co., Ltd.;

[0029] Polyamide resin - 2: PA6 M2400, relative viscosity 2.4, manufacturer: Guangdong Xinhui Meida Nylon Co., Ltd.;

[0030] Polyamide resin - 3: PA6 J1601, relative viscosity 1.7, manufacturer: Hangzhou Juheshun New Materials Co., Ltd.;

[0031] Hexagonal flake magnesium hydroxide - 1: D50 particle size 1.6 μm, side length / thickness 2.2;

[0032] Hexagonal flake magnesium hydroxide - 2: D50 particle size 1 μm, side length / thickness 7.4;

[0033] Hexagonal flake magnesium hydroxide - 3: D50 particle size 2 μm, side length / thickness 13.9;

[0034] Hexagonal flake magnesium hydroxide - 4: D50 particle size 3.5 μm, side length / thickness 22;

[0035] Hexagonal flake magnesium hydroxide - 5: D50 particle size 4.5 μm, side length / thickness 4.5;

[0036] Hexagonal flake magnesium hydroxide - 6: D50 particle size 0.3 μm, side length / thickness 0.77;

[0037] Magnesium hydroxide whisker - 1: average length 52 μm, aspect ratio 65:1;

[0038] Magnesium hydroxide whisker - 2: average length 130 μm, aspect ratio 90:1;

[0039] Magnesium hydroxide whisker - 3: average length 96 μm, aspect ratio 96:1;

[0040] Magnesium hydroxide whisker - 4: average length 150 μm, aspect ratio 125:1;

[0041] Magnesium hydroxide whisker - 5: average length 34 μm, aspect ratio 44:1;

[0042] Hexagonal flake aluminum hydroxide: D50 particle size 2.2 μm, side length / thickness 2;

[0043] Zinc oxide whisker: average length 40 μm, aspect ratio 80:1;

[0044] Magnesium sulfate whisker: average length 50 μm, aspect ratio 62:1;

[0045] Antioxidant: IRGANOX 1098, a hindered phenol antioxidant, manufactured by BASF;

[0046] Lubricant: ester lubricant TR044W, manufactured by Struktol.

[0047] Examples 1 - 12 and Comparative Examples 1 - 8

[0048] The polyamide composite material described in the present invention, the composition components of the polyamide composite material are shown in Table 1 - Table 2. The preparation method of the polyamide composite material includes the following steps:

[0049] (1) Weigh each component by weight;

[0050] (2) Mix the polyamide resin, magnesium hydroxide, and processing aids and add them to an extruder for melt dispersion. The magnesium hydroxide whisker is added to the extruder through a side feeder, and then extrusion granulation is carried out to obtain the polyamide composite material. The screw speed of the twin - screw extruder is 500 rpm, the aspect ratio is 40:1, and the screw temperatures of each section of the extruder from the feeding port to the die head are set as follows: zone 1 160 °C, zone 2 250 °C, zones 3 - 4 240 °C, zones 5 - 7 220 °C, zones 8 - 9 230 °C, die head 260 °C.

[0051] Performance testing

[0052] Thermal conductivity: Measured using a 10mm * 10mm * 0.8mm square sheet according to ASTM E1461-13;

[0053] Tensile strength: Adjusted for 24h at 23℃ / 50%RH and measured according to ISO 527-2-2012 at a test speed of 10mm / min;

[0054] Vertical burning: Injection molded 125 * 13 * 0.8mm combustion specimens and tested for flame retardancy according to UL 94-2023 standard.

[0055] The test results are shown in Table 1 - Table 2

[0056] Table 1

[0057]

[0058] Table 2

[0059]

[0060] As can be seen from the above table, the polyamide composite material prepared in the embodiments of the present invention has a tensile strength ≥ 55MPa, a thermal conductivity ≥ 1.1W / mK, and is flame retardant V-0, having both mechanical and thermal conductivity, and good flame retardant performance.

[0061] From the comparison of Examples 1-3, it can be seen that the relative viscosity of the polyamide resin is 1.5-2.8, and the prepared polyamide composite material has both mechanical and thermal conductivity, and good flame retardant performance.

[0062] From the comparison of Example 1, Examples 4-6, and Comparative Examples 1-2, it can be seen that when the D50 particle size of the hexagonal flake magnesium hydroxide is 1-3.5μm and the ratio of the side length to the thickness of the hexagonal flake magnesium hydroxide is (2-25):1, the prepared polyamide composite material has both mechanical and thermal conductivity, and good flame retardant performance. When the D50 particle size of the hexagonal flake magnesium hydroxide is 1.5-2.5μm and the ratio of the side length to the thickness is (2-15):1, the mechanical and thermal conductivity are better.

[0063] From the comparison of Example 1, Examples 7-9, and Comparative Example 3, it can be seen that when the aspect ratio of the magnesium hydroxide whiskers is (50-150):1 and the average length is 40-180μm, the prepared polyamide composite material has both mechanical and thermal conductivity, and good flame retardant performance. When the aspect ratio of the magnesium hydroxide whiskers is (80-100):1 and the average length is 90-130μm, the mechanical and thermal conductivity are better.

[0064] It can be seen from the comparison of Example 1, Examples 10-12, and Comparative Examples 4-8 that when there are 30-50 parts of polyamide resin, 20-60 parts of magnesium hydroxide, 5-20 parts of magnesium hydroxide whiskers, and 0-3 parts of processing aids, the prepared polyamide composite material has both mechanical and thermal conductivity properties and good flame retardant properties. When there are 35-45 parts of polyamide resin, 35-50 parts of magnesium hydroxide, 10-15 parts of magnesium hydroxide whiskers, and 0-3 parts of processing aids, the mechanical and thermal conductivity properties are better.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyamide composite material, characterized in that: The invention comprises the following components in parts by weight: 30-50 parts of polyamide resin, 30-60 parts of hexagonal flaky magnesium hydroxide, 5-20 parts of magnesium hydroxide whiskers, and 0-3 parts of processing aids; wherein the D50 particle size of the hexagonal flaky magnesium hydroxide is 1-3.5 μm, and the ratio of the side length to the thickness of the hexagonal flaky magnesium hydroxide is (2-25):1; the aspect ratio of the magnesium hydroxide whiskers is (50-150):1, and the average length is 40-180 μm.

2. The polyamide composite material according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 35-45 parts of polyamide resin, 40-50 parts of hexagonal flaky magnesium hydroxide, 10-15 parts of magnesium hydroxide whisker and 0-3 parts of processing aid.

3. The polyamide composite material according to claim 1, characterized in that: The D50 particle size of the hexagonal flaky magnesium hydroxide is 1.5-2.5 μm, and the ratio of side length to thickness is (2-15):

1.

4. The polyamide composite material according to claim 1, characterized in that: The aspect ratio of the magnesium hydroxide whisker is (80-100):1, and the average length is 90-130 μm.

5. The polyamide composite material according to claim 1, characterized in that: The relative viscosity of the polyamide resin is 1.5-2.

8.

6. The polyamide composite material according to claim 1, characterized in that: The processing aid is at least one of an antioxidant and a lubricant; the antioxidant is at least one of a hindered phenol antioxidant, a phosphite antioxidant, an amine antioxidant, and a cuprous halide composite antioxidant; the lubricant is at least one of a hydrocarbon lubricant, an ester lubricant, an alcohol lubricant, a fatty acid lubricant, a fatty acid amide lubricant, and a metal soap lubricant.

7. A method for preparing a polyamide composite material according to any one of claims 1 to 6, characterized in that: The steps include: (1) Weigh each component by weight; (2) The polyamide resin, hexagonal flaky magnesium hydroxide and processing aid are mixed and added to an extruder for melt dispersion, and the magnesium hydroxide whiskers are added to the extruder through a side feed port, and extruded and granulated to obtain the polyamide composite material.

8. Use of the polyamide composite material according to any one of claims 1 to 6 in electronic appliances, automobiles, and LED lighting.

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