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: 30-60 parts of polyamide resin, 12-32 parts of a brominated flame retardant, 4-12 parts of organic phosphinate, 0.1-1 part of a zirconium compound, 0-50 parts of glass fibers, 0-3 parts of an antioxidant and 0-3 parts of a lubricant, and the particle size D50 of the zirconium compound is 0.08-2 [mu] m. According to the antimony-free halogen-containing flame-retardant polyamide composite material provided by the invention, a traditional bromine-antimony flame-retardant system is synergistically replaced by the organic phosphinate and the zirconium compound, and the prepared polyamide composite material has excellent mechanical properties, flame retardance and thermal decomposition stability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polyamide composite material, its preparation method, and its application. Background Technology

[0002] Halogenated flame-retardant polyamides (nylons) are widely used in components such as electrical connectors in the electronics industry due to their excellent flame-retardant efficiency. In traditional halogenated flame-retardant systems, the combination of brominated polystyrene and antimony trioxide is the most common approach: bromine interrupts the combustion chain reaction by capturing free radicals, and antimony trioxide reacts with bromide at high temperatures to form antimony tribromide, which acts as a gaseous free radical scavenger to synergistically block combustion. While this system boasts high flame-retardant efficiency, it has significant drawbacks. Limited global antimony reserves have led to soaring prices, and high concentrations of antimony and its compounds are biotoxic and easily accumulate in the environment. Some countries and regions have already restricted the use of antimony through laws and regulations. Therefore, the development of antimony-free halogenated flame-retardant nylons has become an urgent industry need.

[0003] As electronic and electrical components become smaller and more integrated, electrical connectors face higher demands on the thermal decomposition stability, mechanical properties, and thin-wall flame retardancy of materials. Current antimony-free solutions have the following shortcomings: Patent CN109735100 uses aluminum phosphate to replace antimony trioxide, achieving only a 0.8mm flame retardant V-0 rating, and does not disclose changes in mechanical properties, making it difficult to meet the needs of components under high-temperature conditions; Patent CN104334622A uses metal phosphonates to replace antimony trioxide in styrene polymers, combined with polytetrafluoroethylene anti-dripping agents, achieving only a 1.6mm V-0 rating, also without providing mechanical property data, and with insufficient flame retardant efficiency; In patents CN117986857A and CN119192834A, although zirconium hydroxide can improve the yellowing problem or electrical properties of organophosphorus flame-retardant polyamides, neither mentions its effect on improving flame retardant performance.

[0004] Existing antimony-free halogenated flame-retardant nylon technology struggles to simultaneously achieve high flame retardancy, excellent mechanical properties, and thermal decomposition stability, failing to meet the reliability requirements of electrical connectors operating in high-temperature environments. Therefore, developing an antimony-free flame-retardant system that maintains the high flame-retardant efficiency of polyamide materials while improving their high-temperature mechanical property retention and thermal decomposition stability has become a pressing technical challenge in this field. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a polyamide composite material, its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a polyamide composite material comprising the following components in parts by weight: 30-60 parts of polyamide resin, 12-32 parts of brominated flame retardant, 4-12 parts of organic phosphonate, 0.1-1 parts of zirconium compound, 0-50 parts of glass fiber, 0-3 parts of antioxidant, and 0-3 parts of lubricant; wherein the particle size D50 of the zirconium compound is 0.08-2 μm.

[0007] This invention provides an antimony-free halogenated flame-retardant polyamide composite material. By synergistically replacing the traditional bromine-antimony flame-retardant system with organic phosphinates and zirconium compounds, the prepared polyamide composite material exhibits excellent mechanical properties, flame-retardant properties, and excellent thermal decomposition stability. The organic phosphinate decomposes at high temperatures to generate polyphosphate compounds, promoting the dehydration and carbonization of the polyamide resin to form a dense char layer. This char layer can block heat transfer and oxygen permeation, inhibiting further decomposition of the polymer matrix. The zirconium compound can react with the decomposition products of the organic phosphinate to generate a Zr-PO-containing composite char layer, further improving the high-temperature resistance and oxidation resistance of the char layer. The zirconium compound with a specific particle size D50 of this invention is embedded in the carbon layer, enhancing the mechanical strength and density of the carbon layer, reducing flame retardant failure caused by carbon layer cracking, and further improving the component performance. On the other hand, the zirconium compound with a specific particle size D50 is dispersed in polyamide resin as a physical reinforcing filler, promoting polyamide crystallization through the "nucleation effect", thereby improving mechanical properties. Furthermore, the zirconium compound with a specific particle size D50 can catalyze the cross-linking reaction of polyamide molecular chains, forming a more stable three-dimensional network structure, further improving thermal decomposition stability.

[0008] Preferably, the polyamide resin accounts for not less than 30% by weight in the polyamide composite material.

[0009] Preferably, the polyamide resin accounts for not less than 40% by weight in the polyamide composite material.

[0010] Preferably, the polyamide composite material comprises the following components in parts by weight: 6-8 parts of organic phosphonate and 0.3-0.6 parts of zirconium compound.

[0011] Preferably, the zirconium compound has a particle size D50 of 0.2-1 μm; more preferably, the zirconium compound has a particle size D50 of 0.5-0.8 μm.

[0012] In one embodiment, the polyamide resin is in the range of 30 parts, 35 parts, 40 parts, 45 parts, 48 ​​parts, 50 parts, 55 parts, and 60 parts by weight, or any two of these values; the brominated flame retardant is in the range of 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 30 parts, and 32 parts by weight, or any two of these values; the organic phosphonate is in the range of 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 10 parts, and 12 parts by weight, or any two of these values; and the zirconium compound is in the range of 0.1 parts and 0 parts by weight. The weight of the glass fiber is 0 parts, 3 parts, 0.5 parts, 0.8 parts, 0.9 parts, 1 part, or any two of these values; the weight of the glass fiber is 0 parts, 3 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 48 ​​parts, 50 parts, or any two of these values; the weight of the antioxidant is 0 parts, 1 part, 2 parts, 3 parts, or any two of these values; the weight of the lubricant is 0 parts, 1 part, 2 parts, 3 parts, or any two of these values.

[0013] In one embodiment, the particle size D50 of the zirconium compound is a range of one or any two of the following: 0.08 μm, 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, and 2 μm.

[0014] In one embodiment, the particle size D50 of the zirconium compound is measured using a laser particle size analyzer.

[0015] Preferably, the organic phosphonate includes at least one of aluminum diethylphosphonate, zinc diethylphosphonate, titanium diethylphosphonate, aluminum diisobutylphosphonate, and zinc dibutylphosphonate; more preferably, the organic phosphonate is aluminum diethylphosphonate.

[0016] Preferably, the zirconium compound includes at least one of zirconium hydroxide, zirconium oxide, zirconium tetrachloride, zirconium silicate, zirconium phosphate, zirconium sulfate, zirconium acetate, zirconium fluoride, and zirconium bromide; more preferably, the zirconium compound is zirconium hydroxide.

[0017] In one embodiment, the zirconium compound may be a commercially available product or may be homemade.

[0018] Preferably, the polyamide resin is at least one of nylon 6, nylon 66, nylon 66 / 6, nylon 56, nylon 610, nylon 612, nylon 1010, nylon 1012 or nylon 12.

[0019] Preferably, the polyamide resin has a relative viscosity of 2.0-3.4;

[0020] And / or, the brominated flame retardant is at least one of brominated polystyrene, polybrominated styrene, decabromodiphenyl ethane, and brominated epoxy;

[0021] And / or, the glass fibers have an average length of 50-600 μm and a diameter of 8-15 μm;

[0022] And / or, the antioxidant is at least one of hindered phenolic antioxidants, phosphite antioxidants, amine antioxidants, and cuprous halide composite antioxidants;

[0023] And / or, the lubricant is at least one of hydrocarbon lubricants, ester lubricants, alcohol lubricants, fatty acid lubricants, amide lubricants, and metal soap lubricants.

[0024] In one embodiment, the relative viscosity of the polyamide resin is a range of one or both of the following: 2.0, 2.2, 2.5, 2.8, 3.1, 3.2, 3.3, and 3.4.

[0025] In one embodiment, the method for detecting the relative viscosity of the polyamide resin is as follows: Weigh 0.5g of polyamide resin, transfer it to a 50ml volumetric flask, add about 40ml of 96% concentrated sulfuric acid, and sonicate until the polyamide resin is completely dissolved. Cool the solution to 25°C, dilute it to the mark with concentrated sulfuric acid, and mix it evenly. Measure the flow time of the 0.01g / mL polyamide resin solution at 25°C through an Ubbelohde viscometer, and record it as t1. Measure the flow time of the concentrated sulfuric acid solvent using the same viscometer, and record it as t2. t1 / t2 is the relative viscosity.

[0026] In one embodiment, the average length of the glass fiber is one or any two of the following values: 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, 400 μm, 450 μm, 500 μm, 550 μm, and 600 μm, and the diameter of the glass fiber is one or any two of the following values: 8 μm, 10 μm, 11 μm, 12 μm, 13 μm, and 15 μm.

[0027] In one embodiment, the glass fiber is tested as follows: the sample is calcined in a muffle furnace at 650°C for 1 hour to obtain ash, which is then dispersed in water and observed and tested with an optical microscope to measure the length and diameter of the glass fibers in the ash. A total of 200 fibers are counted and the average value is taken.

[0028] In one embodiment, the hindered phenolic 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], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; the phosphite antioxidant includes (2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and bis(2, At least one of the following: (1) di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, (2) octadecyl pentaerythritol diphosphite, (3) bis(2,4-dicumylphenyl) pentaerythritol diphosphite, (4) 2,2',2”-nitro(triethyl-tri(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)) phosphite, (4) tetra(2,4-di-tert-butylphenyl-4,4'-biphenyl) diphosphite, (4) tetra(2,4-di-tert-butylphenyl)-4,3'-diphenyldiphosphite, (5) tetra(2,4-di-tert-butylphenyl)-3 or 3'-diphenyldiphosphite.

[0029] In one embodiment, the ester lubricant includes at least one of pentaerythritol stearate, glyceryl stearate, and butyl stearate; the amide lubricant includes at least one of ethylene bis-stearamide (EBS), monostearate, and oleamide.

[0030] Furthermore, the present invention provides a method for preparing the aforementioned polyamide composite material, comprising the following steps:

[0031] (1) Weigh each component according to the stated weight proportions;

[0032] (2) The polyamide resin, brominated flame retardant, organic phosphonate, zirconium compound, antioxidant and lubricant are mixed and added to an extruder for melt dispersion. Glass fiber is added to the extruder through the side feed port and extruded and granulated to obtain the polyamide composite material.

[0033] In one embodiment, the twin-screw extruder has a screw speed of 300-800 rpm, a length-to-diameter ratio of 36:1-48:1, a barrel temperature of 160℃-270℃ for each section of the extruder, and a die temperature of 240℃-280℃.

[0034] Furthermore, the present invention provides the application of the polyamide composite material in electronic and electrical appliances; specifically, the present invention provides the application of the polyamide composite material in the manufacture of electrical connectors.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides an antimony-free halogenated flame-retardant polyamide composite material. By synergistically replacing the traditional bromine-antimony flame-retardant system with organic phosphonates and zirconium compounds, the prepared polyamide composite material has excellent mechanical properties after aging, flame-retardant properties and excellent thermal decomposition stability. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments. The purpose is to provide a detailed understanding of the invention, not to limit it. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Unless otherwise specified, the experimental reagents and instruments designed in the embodiments and comparative examples of this invention are commonly used reagents and instruments, all of which are commercially available. Unless otherwise specified, the experimental methods used in the embodiments and comparative examples are conventional methods; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch.

[0037] The raw materials of this invention will now be further described, but are not limited to the following raw materials:

[0038] Polyamide resin-1: PA66 EPR24, relative viscosity 2.4, manufactured by Pingdingshan Shenma Engineering Plastics Co., Ltd.

[0039] Polyamide resin-2: PA6 HY-2800A, relative viscosity 2.8, manufacturer is Haiyang Chemical Fiber;

[0040] Polyamide resin-3: PA6 VOLGAMID F34, relative viscosity 3.4, manufacturer: Kuibyshev Nitrogen;

[0041] Brominated flame retardant: Brominated polystyrene: SAYTEX HP-5010PST, manufactured by Albemarle;

[0042] Organic phosphinate-1: aluminum diethylphosphinate, Exolit OP 1230, manufactured by Clariant;

[0043] Organic phosphonate-2: Zinc diethylphosphonate, manufactured by Maclean's Reagents;

[0044] Organic phosphite-3: aluminum diisobutylphosphite, manufactured by Guangzhou Jinkai New Materials Co., Ltd.

[0045] Inorganic hypophosphite: aluminum hypophosphite, grade M116, manufactured by Shanghai Lidao New Material Technology Co., Ltd.

[0046] Zirconium hydroxide-1: Particle size D50 is 0.1 μm;

[0047] Zirconium hydroxide-2: Particle size D50 is 0.3 μm;

[0048] Zirconium hydroxide-3: particle size D50 is 0.5 μm;

[0049] Zirconium hydroxide-4: particle size D50 is 0.8 μm;

[0050] Zirconium hydroxide-5: Particle size D50 is 1 μm;

[0051] Zirconium hydroxide-6: Particle size D50 is 1.8 μm;

[0052] Zirconium hydroxide-7: particle size D50 is 0.05 μm;

[0053] Zirconium hydroxide-8: Particle size D50 is 2.5 μm;

[0054] Zirconium phosphate: particle size D50 is 0.8 μm;

[0055] Zirconia: Particle size D50 is 0.6 μm;

[0056] Zinc phosphate: Particle size D50 is 1.5 μm;

[0057] Magnesium hydroxide: particle size D50 is 1.2 μm;

[0058] Fiberglass: ECS10-03-568H, average length 3mm, diameter 10μm, manufacturer: Jushi;

[0059] Antioxidant: IRGANOX 1098, a hindered phenolic antioxidant, manufactured by BASF;

[0060] Lubricant: Ester-based lubricant TR044W, manufactured by Struktol.

[0061] Examples and Comparative Examples

[0062] This invention provides a polyamide composite material, the composition of which is shown in Tables 1-2. The preparation method of the polyamide composite material includes the following steps:

[0063] (1) Weigh each component according to its weight parts;

[0064] (2) Polyamide resin, brominated flame retardant, organic phosphinate, zirconium compound, antioxidant, and lubricant are mixed and added to an extruder for melt dispersion. Glass fiber is added to the extruder through a side feed port, and the mixture is extruded and granulated to obtain the polyamide composite material. The screw speed of the twin-screw extruder is 500 rpm, the length-to-diameter ratio is 40:1, and the screw temperatures of each section of the extruder from the feed port to the die head are set as follows: Zone 1 160℃, Zone 2 250℃, Zones 3 to 4 240℃, Zones 5 to 7 220℃, Zones 8 to 9 230℃, and the die head 260℃.

[0065] Performance testing

[0066] (1) Tensile strength retention rate after aging: After conditioning at 23±2℃ and 50±10% humidity for 24h, the initial tensile strength was tested according to ISO527-2-2012; after aging at 180℃ for 1000h, the tensile strength after aging was tested at 23±2℃ and 50±10% humidity for 24h, and then the tensile strength after aging was tested according to ISO 527-2-2012.

[0067] The ratio of tensile strength after aging to initial tensile strength * 100%;

[0068] (2) Vertical burning: According to UL94-2022 standard, the test strip thickness is 0.4mm. The flaming burning time after two burning is recorded as t1 and t2 respectively. The total flaming burning time is t1+t2. The test level is divided into V-0, V-1 and V-2.

[0069] (3) Thermal decomposition stability: According to ISO 11358-1-2014, under nitrogen atmosphere, the temperature was increased from 30℃ to 350℃ at a rate of 20℃ / min, and then held at 350℃ for 30min. The percentage of total weight loss was calculated.

[0070] Table 1

[0071]

[0072]

[0073] Table 2

[0074]

[0075] As shown in the table above, the antimony-free halogenated flame-retardant polyamide composite material provided by the present invention has excellent mechanical properties, flame-retardant properties and excellent thermal decomposition stability after aging; the tensile strength retention rate of the polyamide composite material prepared by the present invention after aging is >70%, the flammability rating is V-0, the thermal decomposition stability is good, and the total weight loss percentage is <2.0%.

[0076] As can be seen from the comparison of Examples 1-3, different polyamide resins, under the synergistic effect of the specific organic phosphonates and zirconium compounds of this invention, all have excellent mechanical properties, flame retardant properties and excellent thermal decomposition stability after aging.

[0077] A comparison of Examples 1 and 4-5 shows that the type of organic hypophosphite affects the performance of the polyamide composite material. When aluminum diethylphosphite is selected, the mechanical properties and thermal decomposition stability after aging are better. A comparison of Examples 1 and Comparative Example 5 shows that when inorganic hypophosphite is selected, its compatibility with nylon is poor, and its mechanical properties, flame retardant properties, and thermal decomposition stability after aging are all poor, failing to meet the requirements.

[0078] A comparison of Examples 1 and 6-10 shows that the particle size D50 of the zirconium compound affects the mechanical properties, flame retardant properties, and thermal decomposition stability of the polyamide composite material after aging. When the particle size D50 of the zirconium compound is 0.08-2 μm, the mechanical properties, flame retardant properties, and thermal decomposition stability after aging are better. A comparison of Examples 1 and Comparative Examples 1-2 shows that if the particle size D50 of the zirconium compound is too large or too small, its compatibility with nylon or its dispersibility in the matrix deteriorates, resulting in poor mechanical properties, flame retardant properties, and thermal decomposition stability after aging, which cannot meet the requirements.

[0079] A comparison of Examples 1 and 11-12 shows that the type of zirconium compound affects the mechanical properties, flame retardant properties, and thermal decomposition stability of the polyamide composite material after aging. When the zirconium compound is zirconium hydroxide, the mechanical properties, flame retardant properties, and thermal decomposition stability after aging are better. A comparison of Examples 1 and Comparative Examples 3-4 shows that when zinc phosphate and magnesium hydroxide are used to replace the zirconium compound in the system, an effective composite char layer cannot be formed, and the mechanical properties, flame retardant properties, and thermal decomposition stability after aging are all poor, failing to meet the requirements.

[0080] As can be seen from the comparison of Examples 1, 13-15 and Comparative Examples 6-7, the weight parts of the components have a certain impact on the performance. When the organic phosphonate is 6-8 parts and the zirconium compound is 0.3-0.6 parts, the mechanical properties and thermal decomposition stability after aging are better.

[0081] As can be seen from the comparison of Example 1 and Comparative Example 8, when the system does not contain zirconium compounds, a Zr-PO composite carbon layer cannot be formed, and the mechanical properties, flame retardant properties and thermal decomposition stability after aging are all poor and cannot meet the requirements.

[0082] 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 modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyamide composite material, characterized in that, It includes the following components in parts by weight: 30-60 parts polyamide resin, 12-32 parts brominated flame retardant, 4-12 parts organic phosphonates, 0.1-1 parts zirconium compounds, 0-50 parts glass fiber, 0-3 parts antioxidant, and 0-3 parts lubricant; The zirconium compound has a particle size D50 of 0.08-2 μm.

2. The polyamide composite material as described in claim 1, characterized in that, It includes the following components in parts by weight: 6-8 parts of organic phosphonate and 0.3-0.6 parts of zirconium compound.

3. The polyamide composite material as described in claim 1, characterized in that, The zirconium compound has a particle size D50 of 0.2-1 μm.

4. The polyamide composite material as described in claim 1, characterized in that, The organic phosphonate includes at least one of aluminum diethylphosphonate, zinc diethylphosphonate, titanium diethylphosphonate, aluminum diisobutylphosphonate, and zinc dibutylphosphonate; preferably, the organic phosphonate is aluminum diethylphosphonate.

5. The polyamide composite material as described in claim 1, characterized in that, The zirconium compound includes at least one of zirconium hydroxide, zirconium oxide, zirconium tetrachloride, zirconium silicate, zirconium phosphate, zirconium sulfate, zirconium acetate, zirconium fluoride, and zirconium bromide; preferably, the zirconium compound is zirconium hydroxide.

6. The polyamide composite material according to claim 1, characterized in that, The relative viscosity of the polyamide resin is 2.0-3.4; And / or, the brominated flame retardant is at least one of brominated polystyrene, polybrominated styrene, decabromodiphenyl ethane, and brominated epoxy; And / or, the glass fibers have an average length of 50-600 μm and a diameter of 8-15 μm; And / or, the antioxidant is at least one of hindered phenolic antioxidants, phosphite antioxidants, amine antioxidants, and cuprous halide composite antioxidants; And / or, the lubricant is at least one of hydrocarbon lubricants, ester lubricants, alcohol lubricants, fatty acid lubricants, amide lubricants, and metal soap lubricants.

7. The method for preparing the polyamide composite material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Weigh each component according to the stated weight proportions; (2) The polyamide resin, brominated flame retardant, organic phosphinate, zirconium compound, antioxidant and lubricant are mixed and added to an extruder for melt dispersion. Glass fiber is added to the extruder through the side feed port and extruded and granulated to obtain the polyamide composite material.

8. The application of a polyamide composite material as described in any one of claims 1-6 in electronic and electrical appliances.

Images