A flame retardant polyamide composite material and its preparation method and application

Abstract

The present invention belongs to the field of engineering plastics technology, and in particular to the field of modified nylon composite materials, and discloses a flame retardant polyamide composite material, a preparation method thereof, and an application thereof. The flame retardant polyamide composite material of the present invention comprises the following components by weight: 20-30 parts of PA56, 60-75 parts of PA66, 0.3-0.8 parts of lubricant, and 6-15 parts of flame retardant; the flame retardant is melamine cyanurate; the terminal amino group content of the PA66 is 35mmol / Kg-50mmol / Kg; the mass ratio of the PA56 to the PA66 is 1:(2-3); and the lubricant is stearate. The flame retardant polyamide composite material of the present invention is made into a sample with good flame retardant stability, while maintaining a low demoulding force and low water absorption of the material. It provides green and environmentally friendly materials for the electronic and electrical industry, while reducing the risk of fire in electronic and electrical products.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, in particular to the field of modified nylon composite materials, and specifically to a flame retardant polyamide composite material and a preparation method and application thereof. Background Art

[0002] Flame-retardant nylon materials offer excellent strength and toughness and are widely used in the electrical and electronics sectors. Due to their application in the electrical and electronics industry, flame retardancy is a key material property of concern. Melamine cyanurate flame-retardant PA66 offers excellent flowability, making it a strong advantage for injection molding thin-walled parts. Its rapid crystallization rate, high efficiency, and excellent toughness make it highly popular in connectors. However, melamine cyanurate flame-retardant PA66 is susceptible to drip ignition, failing to meet V-2 standards, posing significant risks for use in electronic components. Surface-modified melamine cyanurate is commonly used in the market, but this also has poor drip ignition resistance. This material has high process requirements and is extremely sensitive, with even minor process fluctuations resulting in flame retardancy failures. Therefore, a stable flame-retardant material suitable for the electrical and electronics industry is urgently needed.

[0003] In recent years, with the advancement of industry, the detrimental effects of excessive carbon emissions have become increasingly apparent, leading to an international trend towards reducing carbon emissions from materials. Bio-based materials are low-carbon, environmentally friendly, and green, aligning with the "dual carbon" development goals. PA56 is a novel material manufactured using renewable biomass or raw materials derived from biomanufacturing through biological, chemical, and physical methods. Bio-based plastics offer advantages over petroleum-based plastics in terms of carbon reduction and renewability. However, PA56 has drawbacks such as high water absorption, which can lead to dimensional instability in electronic and electrical components, as well as significant performance degradation after water absorption.

[0004] Therefore, it is urgent to address the problems of PA56, such as slow crystallization and high water absorption, which make product demolding difficult, and rapid performance degradation due to high water absorption. Furthermore, the existing MCA flame-retardant PA66 material suffers from poor flame retardancy and the risk of dripping and ignition due to poor dispersion of the flame retardant. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a flame retardant polyamide composite material and a preparation method and application thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a flame-retardant polyamide composite material, comprising the following components, by weight: 15-30 parts of PA56, 60-75 parts of PA66, 0.3-0.8 parts of a lubricant, and 6-15 parts of a flame retardant; the flame retardant is melamine cyanurate;

[0008] The terminal amino group content of the PA66 is 35mmol / Kg-50mmol / Kg (the terminal amino group content is detected by titrating the sample with a fully automatic potentiometric titrator)

[0009] PA56 is a poly (pentamethylenediamine adipate) polymerized from bio-based pentamethylenediamine and petroleum-based adipic acid. Bio-based pentamethylenediamine can be obtained through microbial fermentation or by constructing an Escherichia coli system using a whole-cell method to directly convert lysine into pentamethylenediamine.

[0010] The mass ratio of the PA56 to the PA66 is 1:(2-3);

[0011] The lubricant is stearate.

[0012] The present invention reduces the carbon emissions of the material by balancing the mass ratio of PA56 and PA66. At the same time, PA66 resin with a suitable end amino group content is selected to cooperate with stearate to promote the dispersion performance of the melamine cyanurate flame retardant, so that the particle size of the melamine cyanurate flame retardant is smaller and more uniform, the flame retardant performance is stable, and it is more conducive to compatibility with PA56. The crystallization speed and crystallinity of the flame retardant polyamide composite material will not be greatly reduced, ensuring that the composite material has good demoulding properties and low water absorption.

[0013] Preferably, in the flame retardant polyamide composite material, the sum of the mass percentages of PA56 and PA66 is not less than 79%.

[0014] Preferably, the terminal amino group content of the PA66 is within the range of any one or both of 35 mmol / Kg, 36 mmol / Kg, 37 mmol / Kg, 38 mmol / Kg, 39 mmol / Kg, 40 mmol / Kg, 41 mmol / Kg, 42 mmol / Kg, 43 mmol / Kg, 44 mmol / Kg, 45 mmol / Kg, 46 mmol / Kg, 47 mmol / Kg, 48 mmol / Kg, 49 mmol / Kg and 50 mmol / Kg.

[0015] As a preferred embodiment of the flame-retardant polyamide composite material of the present invention, the intrinsic viscosity of the PA56 is 2.4 dL / g-2.7 dL / g.

[0016] Preferably, the intrinsic viscosity of the PA56 is within the range of any one or both of 2.4 dL / g, 2.5 dL / g, 2.6 dL / g and 2.7 dL / g.

[0017] Preferably, the intrinsic viscosity of the PA66 is 2.4 dL / g-3.2 dL / g, and is within the range of any one or both of 2.4 dL / g, 2.5 dL / g, 2.6 dL / g, 2.7 dL / g, 2.8 dL / g, 2.9 dL / g, 3.0 dL / g, 3.1 dL / g, and 3.2 dL / g.

[0018] The PA66 includes homopolymer PA66 or copolymer PA66, such as PA66 / 6.

[0019] The intrinsic viscosity of PA56 and PA66 is tested according to ISO 307 test standard.

[0020] As a preferred embodiment of the flame-retardant polyamide composite material of the present invention, the stearate is aluminum distearate.

[0021] Preferably, the flame retardant polyamide composite material of the present invention does not contain a toughening agent, such as a maleic anhydride graft copolymer.

[0022] In a second aspect, the present invention provides a method for preparing the flame retardant polyamide composite material, comprising the following steps:

[0023] The components are taken, mixed, melt-extruded, and granulated to obtain the product.

[0024] As a preferred embodiment of the preparation method of the present invention, during the extrusion, the screw aspect ratio of the twin-screw extruder is (40-48):1, the barrel temperature is 220°C-270°C, and the screw speed is 200rpm-450rpm.

[0025] In a third aspect, the present invention applies the flame-retardant polyamide composite material to electronic and electrical products, including connectors, electric control boxes, plugs, and other products.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention balances the mass ratio of PA56 and PA66 to reduce the carbon emissions of the material. Furthermore, the invention selects a PA66 resin with an appropriate end amino group content and uses stearate to enhance the dispersion of the melamine cyanurate flame retardant, resulting in a smaller and more uniform particle size of the melamine cyanurate flame retardant, stable flame retardancy, and improved compatibility with PA56. This prevents a significant decrease in the crystallization rate and crystallinity of the flame-retardant polyamide composite material, ensuring that the composite material has good demolding properties and low water absorption. Specifically, the flame-retardant polyamide composite material of the present invention has significantly reduced carbon emissions, significantly improved flame retardant stability, and good demolding properties and suitable water absorption, providing a green and environmentally friendly material for the electronics and electrical appliance industry. DETAILED DESCRIPTION

[0028] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are intended only to explain the present invention and are not intended to limit the present invention. In the present invention, technical features described as open-ended include both closed-ended technical solutions consisting of the enumerated features and open-ended technical solutions containing the enumerated features.

[0029] In the following examples and comparative examples, unless otherwise specified, lubricants were obtained from commercial sources, and the same lubricants were used in parallel experiments.

[0030] In the following examples and comparative examples, the performance testing method is as follows:

[0031] (1) Flame retardant stability (dripping ignition): 0.75 mm thick combustion specimens were injection molded and the UL 94 standard was used to test the combustion performance of the material.

[0032] (2) Demolding force: Using an injection molding machine, the temperatures from the nozzle to the discharge port are: 265℃, 260℃, 260℃, 250℃, medium pressure and medium speed. Under the same conditions, the following products are injected and the demolding force is monitored.

[0033] (3) Water absorption: 1.0 mm thick, boiled in 85°C for 2 h, weighed the mass change before and after boiling, and the difference in mass change divided by the mass before boiling was the percentage of water absorption.

[0034] The raw materials used in the following examples and comparative examples are described below, but are not limited to these materials:

[0035] PA56, brand 1273, purchased from Shanghai Cathay, with an intrinsic viscosity of 2.62 dL / g.

[0036] PA56, brand 1251, purchased from Shanghai Cathay, with an intrinsic viscosity of 2.45 dL / g.

[0037] The intrinsic viscosity of the above PA56 is tested according to ISO 307 test standard.

[0038] PA66-A: PA66 EPR32, purchased from Shenma, with an amino terminal content of 24 mmol / Kg.

[0039] PA66-B: PA66 24FE2K, purchased from Rhodia, with a terminal amino group content of 49 mmol / Kg.

[0040] PA66-C: PA66 27AE1K, purchased from Rhodia, with a terminal amino content of 40 mmol / kg. PA66-D: PA6688X, purchased from ASCEND, with a terminal amino content of 37 mmol / kg. PA66-E: PA66 EP158NH, purchased from Zhejiang Huafeng, with a terminal amino content of 82 mmol / kg.

[0041] The amino group content of the PA66 sample was titrated using a fully automatic potentiometric titrator. 0.5g of polymer was added to 45mL of phenol and 3mL of anhydrous methanol, heated to reflux, and after complete dissolution, the sample was cooled to room temperature and titrated with a standardized hydrochloric acid solution to determine the amino group content. The flame retardant, melamine cyanurate, was purchased from the Sichuan Fine Chemical Research Institute.

[0042] Lubricant-A, stearate, aluminum distearate, commercially available.

[0043] Lubricant-B, fatty ester, TR044W, purchased from Struktol, USA.

[0044] Lubricant-C, oxidized polyethylene wax, and Lubricant-A-C540A were purchased from Honeywell.

[0045] Lubricant-D, stearate, calcium stearate, commercially available.

[0046] Lubricant-E, stearate, lithium stearate, commercially available.

[0047] Toughening agent: Maleic anhydride graft copolymers include POE-g-MAH and FUSABON DN493, purchased from DuPont, USA.

[0048] The components of the flame retardant polyamide composite materials of the examples and comparative examples are shown in Table 1.

[0049] The preparation method of the flame-retardant polyamide composite material of the embodiment and comparative example in Table 1 comprises the following steps:

[0050] PA56, PA66, lubricant, and flame retardant were weighed according to the formula in Table 1, and the above components were placed in a mixer and mixed until uniform to obtain a premix; the obtained premix was then placed in a twin-screw extruder for melt mixing, and extruded into pellets to obtain a flame-retardant polyamide composite material;

[0051] The twin-screw extruder has a screw length-diameter ratio of 40 to 48:1, a barrel temperature of 220 to 270° C., and a screw speed of 200 to 450 rpm.

[0052] Table 1 Components of the flame retardant polyamide composite materials of the examples and comparative examples (parts by weight)

[0053]

[0054] The performance test results of the flame retardant polyamide composite materials of the examples and comparative examples are shown in Table 2.

[0055] Table 2 Components of the flame retardant polyamide composite materials of the embodiments and comparative examples (parts by weight)

[0056]

[0057] As shown in Table 2, the flame-retardant polyamide composite material of the present invention, made from raw materials such as PA66 and PA56 with specific end-amino group contents, a lubricant, and a flame retardant, exhibits excellent flame retardant stability (V-0), while maintaining low demolding forces (585-613 bar) and low water absorption (3.0%-3.2%). This significantly reduces the composite material's carbon emissions, providing a green and environmentally friendly material for the electrical and electronics industry while also reducing the risk of fire in electronic and electrical products.

[0058] Compared to Example 1, the terminal amino group contents of PA66 used in the composite materials of Comparative Examples 1 and 2 were 24 mmol / kg and 82 mmol / kg, respectively, resulting in poor flame retardancy and stability, high demolding force, and poor water absorption. The lubricants used in the composite materials of Comparative Examples 3 and 4 were fatty esters and oxidized polyethylene wax, respectively, resulting in poor flame retardancy and stability, high demolding force, and poor water absorption. The mass ratios of PA56 and PA66 used in the composite materials of Comparative Examples 5 and 6 were 1:1.5 and 1:4, respectively, resulting in high demolding force and poor water absorption in the composite material of Comparative Example 5, and poor flame retardancy and water absorption in the composite material of Comparative Example 6. The composite material system of Comparative Example 7 also included a toughening agent, resulting in poor flame retardancy and stability and high demolding force.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A flame retardant polyamide composite material, characterized in that: The composition comprises the following components by weight: 20-30 parts of PA56, 60-75 parts of PA66, 0.3-0.8 parts of lubricant, and 6-15 parts of flame retardant; The flame retardant is melamine cyanurate; The terminal amino group content of the PA66 is 35 mmol / Kg-50 mmol / Kg; The mass ratio of the PA56 to the PA66 is 1:(2-3); The lubricant is stearate, and the stearate is one of aluminum distearate, calcium stearate, and lithium stearate; The flame retardant polyamide composite material does not contain maleic anhydride graft copolymer.

2. The flame retardant polyamide composite material according to claim 1, characterized in that: The terminal amino group content of the PA66 is 40 mmol / Kg-49 mmol / Kg.

3. The flame retardant polyamide composite material according to claim 1, characterized in that: The intrinsic viscosity of the PA56 is 2.4 dL / g-2.7 dL / g, and the testing method is ISO-307.

4. The method for preparing the flame retardant polyamide composite material according to any one of claims 1 to 3, characterized in that: The following steps are involved: The components are taken, mixed, melt-extruded, and granulated to obtain the product.

5. The preparation method according to claim 4, characterized in that During the extrusion, the screw length-diameter ratio of the twin-screw extruder is (40-48):1, the barrel temperature is 220° C.-270° C., and the screw speed is 200 rpm-450 rpm.

6. Use of the flame retardant polyamide composite material according to any one of claims 1 to 3 in electronic and electrical products.

Images